Merge tag 'trace-v5.14' of git://git.kernel.org/pub/scm/linux/kernel/git/rostedt/linux-trace

Pull tracing updates from Steven Rostedt:

- Added option for per CPU threads to the hwlat tracer

- Have hwlat tracer handle hotplug CPUs

- New tracer: osnoise, that detects latency caused by interrupts,
softirqs and scheduling of other tasks.

- Added timerlat tracer that creates a thread and measures in detail
what sources of latency it has for wake ups.

- Removed the "success" field of the sched_wakeup trace event. This has
been hardcoded as "1" since 2015, no tooling should be looking at it
now. If one exists, we can revert this commit, fix that tool and try
to remove it again in the future.

- tgid mapping fixed to handle more than PID_MAX_DEFAULT pids/tgids.

- New boot command line option "tp_printk_stop", as tp_printk causes
trace events to write to console. When user space starts, this can
easily live lock the system. Having a boot option to stop just after
boot up is useful to prevent that from happening.

- Have ftrace_dump_on_oops boot command line option take numbers that
match the numbers shown in /proc/sys/kernel/ftrace_dump_on_oops.

- Bootconfig clean ups, fixes and enhancements.

- New ktest script that tests bootconfig options.

- Add tracepoint_probe_register_may_exist() to register a tracepoint
without triggering a WARN*() if it already exists. BPF has a path
from user space that can do this. All other paths are considered a
bug.

- Small clean ups and fixes

* tag 'trace-v5.14' of git://git.kernel.org/pub/scm/linux/kernel/git/rostedt/linux-trace: (49 commits)
tracing: Resize tgid_map to pid_max, not PID_MAX_DEFAULT
tracing: Simplify & fix saved_tgids logic
treewide: Add missing semicolons to __assign_str uses
tracing: Change variable type as bool for clean-up
trace/timerlat: Fix indentation on timerlat_main()
trace/osnoise: Make 'noise' variable s64 in run_osnoise()
tracepoint: Add tracepoint_probe_register_may_exist() for BPF tracing
tracing: Fix spelling in osnoise tracer "interferences" -> "interference"
Documentation: Fix a typo on trace/osnoise-tracer
trace/osnoise: Fix return value on osnoise_init_hotplug_support
trace/osnoise: Make interval u64 on osnoise_main
trace/osnoise: Fix 'no previous prototype' warnings
tracing: Have osnoise_main() add a quiescent state for task rcu
seq_buf: Make trace_seq_putmem_hex() support data longer than 8
seq_buf: Fix overflow in seq_buf_putmem_hex()
trace/osnoise: Support hotplug operations
trace/hwlat: Support hotplug operations
trace/hwlat: Protect kdata->kthread with get/put_online_cpus
trace: Add timerlat tracer
trace: Add osnoise tracer
...

Documentation/admin-guide/bootconfig.rst

···
 
 In this case, the key ``foo`` has ``bar``, ``baz`` and ``qux``.
 
-However, a sub-key and a value can not co-exist under a parent key.
-For example, following config is NOT allowed.::
+Moreover, sub-keys and a value can coexist under a parent key.
+For example, following config is allowed.::
 
  foo = value1
- foo.bar = value2 # !ERROR! subkey "bar" and value "value1" can NOT co-exist
- foo.bar := value2 # !ERROR! even with the override operator, this is NOT allowed.
+ foo.bar = value2
+ foo := value3 # This will update foo's value.
 
+Note, since there is no syntax to put a raw value directly under a
+structured key, you have to define it outside of the brace. For example::
+
+ foo {
+     bar = value1
+     bar {
+         baz = value2
+         qux = value3
+     }
+ }
+
+Also, the order of the value node under a key is fixed. If there
+are a value and subkeys, the value is always the first child node
+of the key. Thus if user specifies subkeys first, e.g.::
+
+ foo.bar = value1
+ foo = value2
+
+In the program (and /proc/bootconfig), it will be shown as below::
+
+ foo = value2
+ foo.bar = value1
 
 Comments
 --------

Documentation/admin-guide/kernel-parameters.txt

···
 			Note, echoing 1 into this file without the
 			tracepoint_printk kernel cmdline option has no effect.
 
+			The tp_printk_stop_on_boot (see below) can also be used
+			to stop the printing of events to console at
+			late_initcall_sync.
+
 			** CAUTION **
 
 			Having tracepoints sent to printk() and activating high
 			frequency tracepoints such as irq or sched, can cause
 			the system to live lock.
+
+	tp_printk_stop_on_boot[FTRACE]
+			When tp_printk (above) is set, it can cause a lot of noise
+			on the console. It may be useful to only include the
+			printing of events during boot up, as user space may
+			make the system inoperable.
+
+			This command line option will stop the printing of events
+			to console at the late_initcall_sync() time frame.
 
 	traceoff_on_warning
 			[FTRACE] enable this option to disable tracing when a

Documentation/trace/boottime-trace.rst

···
 ftrace.[instance.INSTANCE.]event.GROUP.EVENT.enable
    Enable GROUP:EVENT tracing.
 
+ftrace.[instance.INSTANCE.]event.GROUP.enable
+   Enable all event tracing within GROUP.
+
+ftrace.[instance.INSTANCE.]event.enable
+   Enable all event tracing.
+
 ftrace.[instance.INSTANCE.]event.GROUP.EVENT.filter = FILTER
    Set FILTER rule to the GROUP:EVENT.
 

Documentation/trace/hwlat_detector.rst

···
  - tracing_cpumask	- the CPUs to move the hwlat thread across
  - hwlat_detector/width	- specified amount of time to spin within window (usecs)
  - hwlat_detector/window	- amount of time between (width) runs (usecs)
+ - hwlat_detector/mode	- the thread mode
 
-The hwlat detector's kernel thread will migrate across each CPU specified in
-tracing_cpumask between each window. To limit the migration, either modify
-tracing_cpumask, or modify the hwlat kernel thread (named [hwlatd]) CPU
-affinity directly, and the migration will stop.
+By default, one hwlat detector's kernel thread will migrate across each CPU
+specified in cpumask at the beginning of a new window, in a round-robin
+fashion. This behavior can be changed by changing the thread mode,
+the available options are:
+
+ - none:        do not force migration
+ - round-robin: migrate across each CPU specified in cpumask [default]
+ - per-cpu:     create one thread for each cpu in tracing_cpumask

Documentation/trace/index.rst

···
    histogram-design
    boottime-trace
    hwlat_detector
+   osnoise-tracer
+   timerlat-tracer
    intel_th
    ring-buffer-design
    stm

Documentation/trace/osnoise-tracer.rst

···
+==============
+OSNOISE Tracer
+==============
+
+In the context of high-performance computing (HPC), the Operating System
+Noise (*osnoise*) refers to the interference experienced by an application
+due to activities inside the operating system. In the context of Linux,
+NMIs, IRQs, SoftIRQs, and any other system thread can cause noise to the
+system. Moreover, hardware-related jobs can also cause noise, for example,
+via SMIs.
+
+hwlat_detector is one of the tools used to identify the most complex
+source of noise: *hardware noise*.
+
+In a nutshell, the hwlat_detector creates a thread that runs
+periodically for a given period. At the beginning of a period, the thread
+disables interrupt and starts sampling. While running, the hwlatd
+thread reads the time in a loop. As interrupts are disabled, threads,
+IRQs, and SoftIRQs cannot interfere with the hwlatd thread. Hence, the
+cause of any gap between two different reads of the time roots either on
+NMI or in the hardware itself. At the end of the period, hwlatd enables
+interrupts and reports the max observed gap between the reads. It also
+prints a NMI occurrence counter. If the output does not report NMI
+executions, the user can conclude that the hardware is the culprit for
+the latency. The hwlat detects the NMI execution by observing
+the entry and exit of a NMI.
+
+The osnoise tracer leverages the hwlat_detector by running a
+similar loop with preemption, SoftIRQs and IRQs enabled, thus allowing
+all the sources of *osnoise* during its execution. Using the same approach
+of hwlat, osnoise takes note of the entry and exit point of any
+source of interferences, increasing a per-cpu interference counter. The
+osnoise tracer also saves an interference counter for each source of
+interference. The interference counter for NMI, IRQs, SoftIRQs, and
+threads is increased anytime the tool observes these interferences' entry
+events. When a noise happens without any interference from the operating
+system level, the hardware noise counter increases, pointing to a
+hardware-related noise. In this way, osnoise can account for any
+source of interference. At the end of the period, the osnoise tracer
+prints the sum of all noise, the max single noise, the percentage of CPU
+available for the thread, and the counters for the noise sources.
+
+Usage
+-----
+
+Write the ASCII text "osnoise" into the current_tracer file of the
+tracing system (generally mounted at /sys/kernel/tracing).
+
+For example::
+
+        [root@f32 ~]# cd /sys/kernel/tracing/
+        [root@f32 tracing]# echo osnoise > current_tracer
+
+It is possible to follow the trace by reading the trace trace file::
+
+        [root@f32 tracing]# cat trace
+        # tracer: osnoise
+        #
+        #                                _-----=> irqs-off
+        #                               / _----=> need-resched
+        #                              | / _---=> hardirq/softirq
+        #                              || / _--=> preempt-depth                            MAX
+        #                              || /                                             SINGLE     Interference counters:
+        #                              ||||               RUNTIME      NOISE   % OF CPU  NOISE    +-----------------------------+
+        #           TASK-PID      CPU# ||||   TIMESTAMP    IN US       IN US  AVAILABLE  IN US     HW    NMI    IRQ   SIRQ THREAD
+        #              | |         |   ||||      |           |             |    |            |      |      |      |      |      |
+                   <...>-859     [000] ....    81.637220: 1000000        190  99.98100       9     18      0   1007     18      1
+                   <...>-860     [001] ....    81.638154: 1000000        656  99.93440      74     23      0   1006     16      3
+                   <...>-861     [002] ....    81.638193: 1000000       5675  99.43250     202      6      0   1013     25     21
+                   <...>-862     [003] ....    81.638242: 1000000        125  99.98750      45      1      0   1011     23      0
+                   <...>-863     [004] ....    81.638260: 1000000       1721  99.82790     168      7      0   1002     49     41
+                   <...>-864     [005] ....    81.638286: 1000000        263  99.97370      57      6      0   1006     26      2
+                   <...>-865     [006] ....    81.638302: 1000000        109  99.98910      21      3      0   1006     18      1
+                   <...>-866     [007] ....    81.638326: 1000000       7816  99.21840     107      8      0   1016     39     19
+
+In addition to the regular trace fields (from TASK-PID to TIMESTAMP), the
+tracer prints a message at the end of each period for each CPU that is
+running an osnoise/ thread. The osnoise specific fields report:
+
+ - The RUNTIME IN US reports the amount of time in microseconds that
+   the osnoise thread kept looping reading the time.
+ - The NOISE IN US reports the sum of noise in microseconds observed
+   by the osnoise tracer during the associated runtime.
+ - The % OF CPU AVAILABLE reports the percentage of CPU available for
+   the osnoise thread during the runtime window.
+ - The MAX SINGLE NOISE IN US reports the maximum single noise observed
+   during the runtime window.
+ - The Interference counters display how many each of the respective
+   interference happened during the runtime window.
+
+Note that the example above shows a high number of HW noise samples.
+The reason being is that this sample was taken on a virtual machine,
+and the host interference is detected as a hardware interference.
+
+Tracer options
+---------------------
+
+The tracer has a set of options inside the osnoise directory, they are:
+
+ - osnoise/cpus: CPUs at which a osnoise thread will execute.
+ - osnoise/period_us: the period of the osnoise thread.
+ - osnoise/runtime_us: how long an osnoise thread will look for noise.
+ - osnoise/stop_tracing_us: stop the system tracing if a single noise
+   higher than the configured value happens. Writing 0 disables this
+   option.
+ - osnoise/stop_tracing_total_us: stop the system tracing if total noise
+   higher than the configured value happens. Writing 0 disables this
+   option.
+ - tracing_threshold: the minimum delta between two time() reads to be
+   considered as noise, in us. When set to 0, the default value will
+   will be used, which is currently 5 us.
+
+Additional Tracing
+------------------
+
+In addition to the tracer, a set of tracepoints were added to
+facilitate the identification of the osnoise source.
+
+ - osnoise:sample_threshold: printed anytime a noise is higher than
+   the configurable tolerance_ns.
+ - osnoise:nmi_noise: noise from NMI, including the duration.
+ - osnoise:irq_noise: noise from an IRQ, including the duration.
+ - osnoise:softirq_noise: noise from a SoftIRQ, including the
+   duration.
+ - osnoise:thread_noise: noise from a thread, including the duration.
+
+Note that all the values are *net values*. For example, if while osnoise
+is running, another thread preempts the osnoise thread, it will start a
+thread_noise duration at the start. Then, an IRQ takes place, preempting
+the thread_noise, starting a irq_noise. When the IRQ ends its execution,
+it will compute its duration, and this duration will be subtracted from
+the thread_noise, in such a way as to avoid the double accounting of the
+IRQ execution. This logic is valid for all sources of noise.
+
+Here is one example of the usage of these tracepoints::
+
+       osnoise/8-961     [008] d.h.  5789.857532: irq_noise: local_timer:236 start 5789.857529929 duration 1845 ns
+       osnoise/8-961     [008] dNh.  5789.858408: irq_noise: local_timer:236 start 5789.858404871 duration 2848 ns
+     migration/8-54      [008] d...  5789.858413: thread_noise: migration/8:54 start 5789.858409300 duration 3068 ns
+       osnoise/8-961     [008] ....  5789.858413: sample_threshold: start 5789.858404555 duration 8812 ns interferences 2
+
+In this example, a noise sample of 8 microseconds was reported in the last
+line, pointing to two interferences. Looking backward in the trace, the
+two previous entries were about the migration thread running after a
+timer IRQ execution. The first event is not part of the noise because
+it took place one millisecond before.
+
+It is worth noticing that the sum of the duration reported in the
+tracepoints is smaller than eight us reported in the sample_threshold.
+The reason roots in the overhead of the entry and exit code that happens
+before and after any interference execution. This justifies the dual
+approach: measuring thread and tracing.

Documentation/trace/timerlat-tracer.rst

···
+###############
+Timerlat tracer
+###############
+
+The timerlat tracer aims to help the preemptive kernel developers to
+find souces of wakeup latencies of real-time threads. Like cyclictest,
+the tracer sets a periodic timer that wakes up a thread. The thread then
+computes a *wakeup latency* value as the difference between the *current
+time* and the *absolute time* that the timer was set to expire. The main
+goal of timerlat is tracing in such a way to help kernel developers.
+
+Usage
+-----
+
+Write the ASCII text "timerlat" into the current_tracer file of the
+tracing system (generally mounted at /sys/kernel/tracing).
+
+For example::
+
+        [root@f32 ~]# cd /sys/kernel/tracing/
+        [root@f32 tracing]# echo timerlat > current_tracer
+
+It is possible to follow the trace by reading the trace trace file::
+
+  [root@f32 tracing]# cat trace
+  # tracer: timerlat
+  #
+  #                              _-----=> irqs-off
+  #                             / _----=> need-resched
+  #                            | / _---=> hardirq/softirq
+  #                            || / _--=> preempt-depth
+  #                            || /
+  #                            ||||             ACTIVATION
+  #         TASK-PID      CPU# ||||   TIMESTAMP    ID            CONTEXT                LATENCY
+  #            | |         |   ||||      |         |                  |                       |
+          <idle>-0       [000] d.h1    54.029328: #1     context    irq timer_latency       932 ns
+           <...>-867     [000] ....    54.029339: #1     context thread timer_latency     11700 ns
+          <idle>-0       [001] dNh1    54.029346: #1     context    irq timer_latency      2833 ns
+           <...>-868     [001] ....    54.029353: #1     context thread timer_latency      9820 ns
+          <idle>-0       [000] d.h1    54.030328: #2     context    irq timer_latency       769 ns
+           <...>-867     [000] ....    54.030330: #2     context thread timer_latency      3070 ns
+          <idle>-0       [001] d.h1    54.030344: #2     context    irq timer_latency       935 ns
+           <...>-868     [001] ....    54.030347: #2     context thread timer_latency      4351 ns
+
+
+The tracer creates a per-cpu kernel thread with real-time priority that
+prints two lines at every activation. The first is the *timer latency*
+observed at the *hardirq* context before the activation of the thread.
+The second is the *timer latency* observed by the thread. The ACTIVATION
+ID field serves to relate the *irq* execution to its respective *thread*
+execution.
+
+The *irq*/*thread* splitting is important to clarify at which context
+the unexpected high value is coming from. The *irq* context can be
+delayed by hardware related actions, such as SMIs, NMIs, IRQs
+or by a thread masking interrupts. Once the timer happens, the delay
+can also be influenced by blocking caused by threads. For example, by
+postponing the scheduler execution via preempt_disable(), by the
+scheduler execution, or by masking interrupts. Threads can
+also be delayed by the interference from other threads and IRQs.
+
+Tracer options
+---------------------
+
+The timerlat tracer is built on top of osnoise tracer.
+So its configuration is also done in the osnoise/ config
+directory. The timerlat configs are:
+
+ - cpus: CPUs at which a timerlat thread will execute.
+ - timerlat_period_us: the period of the timerlat thread.
+ - osnoise/stop_tracing_us: stop the system tracing if a
+   timer latency at the *irq* context higher than the configured
+   value happens. Writing 0 disables this option.
+ - stop_tracing_total_us: stop the system tracing if a
+   timer latency at the *thread* context higher than the configured
+   value happens. Writing 0 disables this option.
+ - print_stack: save the stack of the IRQ ocurrence, and print
+   it afte the *thread context* event".
+
+timerlat and osnoise
+----------------------------
+
+The timerlat can also take advantage of the osnoise: traceevents.
+For example::
+
+        [root@f32 ~]# cd /sys/kernel/tracing/
+        [root@f32 tracing]# echo timerlat > current_tracer
+        [root@f32 tracing]# echo 1 > events/osnoise/enable
+        [root@f32 tracing]# echo 25 > osnoise/stop_tracing_total_us
+        [root@f32 tracing]# tail -10 trace
+             cc1-87882   [005] d..h...   548.771078: #402268 context    irq timer_latency     13585 ns
+             cc1-87882   [005] dNLh1..   548.771082: irq_noise: local_timer:236 start 548.771077442 duration 7597 ns
+             cc1-87882   [005] dNLh2..   548.771099: irq_noise: qxl:21 start 548.771085017 duration 7139 ns
+             cc1-87882   [005] d...3..   548.771102: thread_noise:      cc1:87882 start 548.771078243 duration 9909 ns
+      timerlat/5-1035    [005] .......   548.771104: #402268 context thread timer_latency     39960 ns
+
+In this case, the root cause of the timer latency does not point to a
+single cause, but to multiple ones. Firstly, the timer IRQ was delayed
+for 13 us, which may point to a long IRQ disabled section (see IRQ
+stacktrace section). Then the timer interrupt that wakes up the timerlat
+thread took 7597 ns, and the qxl:21 device IRQ took 7139 ns. Finally,
+the cc1 thread noise took 9909 ns of time before the context switch.
+Such pieces of evidence are useful for the developer to use other
+tracing methods to figure out how to debug and optimize the system.
+
+It is worth mentioning that the *duration* values reported
+by the osnoise: events are *net* values. For example, the
+thread_noise does not include the duration of the overhead caused
+by the IRQ execution (which indeed accounted for 12736 ns). But
+the values reported by the timerlat tracer (timerlat_latency)
+are *gross* values.
+
+The art below illustrates a CPU timeline and how the timerlat tracer
+observes it at the top and the osnoise: events at the bottom. Each "-"
+in the timelines means circa 1 us, and the time moves ==>::
+
+      External     timer irq                   thread
+       clock        latency                    latency
+       event        13585 ns                   39960 ns
+         |             ^                         ^
+         v             |                         |
+         |-------------|                         |
+         |-------------+-------------------------|
+                       ^                         ^
+  ========================================================================
+                    [tmr irq]  [dev irq]
+  [another thread...^       v..^       v.......][timerlat/ thread]  <-- CPU timeline
+  =========================================================================
+                    |-------|  |-------|
+                            |--^       v-------|
+                            |          |       |
+                            |          |       + thread_noise: 9909 ns
+                            |          +-> irq_noise: 6139 ns
+                            +-> irq_noise: 7597 ns
+
+IRQ stacktrace
+---------------------------
+
+The osnoise/print_stack option is helpful for the cases in which a thread
+noise causes the major factor for the timer latency, because of preempt or
+irq disabled. For example::
+
+        [root@f32 tracing]# echo 500 > osnoise/stop_tracing_total_us
+        [root@f32 tracing]# echo 500 > osnoise/print_stack
+        [root@f32 tracing]# echo timerlat > current_tracer
+        [root@f32 tracing]# tail -21 per_cpu/cpu7/trace
+          insmod-1026    [007] dN.h1..   200.201948: irq_noise: local_timer:236 start 200.201939376 duration 7872 ns
+          insmod-1026    [007] d..h1..   200.202587: #29800 context    irq timer_latency      1616 ns
+          insmod-1026    [007] dN.h2..   200.202598: irq_noise: local_timer:236 start 200.202586162 duration 11855 ns
+          insmod-1026    [007] dN.h3..   200.202947: irq_noise: local_timer:236 start 200.202939174 duration 7318 ns
+          insmod-1026    [007] d...3..   200.203444: thread_noise:   insmod:1026 start 200.202586933 duration 838681 ns
+      timerlat/7-1001    [007] .......   200.203445: #29800 context thread timer_latency    859978 ns
+      timerlat/7-1001    [007] ....1..   200.203446: <stack trace>
+  => timerlat_irq
+  => __hrtimer_run_queues
+  => hrtimer_interrupt
+  => __sysvec_apic_timer_interrupt
+  => asm_call_irq_on_stack
+  => sysvec_apic_timer_interrupt
+  => asm_sysvec_apic_timer_interrupt
+  => delay_tsc
+  => dummy_load_1ms_pd_init
+  => do_one_initcall
+  => do_init_module
+  => __do_sys_finit_module
+  => do_syscall_64
+  => entry_SYSCALL_64_after_hwframe
+
+In this case, it is possible to see that the thread added the highest
+contribution to the *timer latency* and the stack trace, saved during
+the timerlat IRQ handler, points to a function named
+dummy_load_1ms_pd_init, which had the following code (on purpose)::
+
+	static int __init dummy_load_1ms_pd_init(void)
+	{
+		preempt_disable();
+		mdelay(1);
+		preempt_enable();
+		return 0;
+
+	}

arch/x86/kernel/Makefile

···
 obj-$(CONFIG_FUNCTION_GRAPH_TRACER) += ftrace.o
 obj-$(CONFIG_FTRACE_SYSCALLS)	+= ftrace.o
 obj-$(CONFIG_X86_TSC)		+= trace_clock.o
+obj-$(CONFIG_TRACING)		+= trace.o
 obj-$(CONFIG_CRASH_CORE)	+= crash_core_$(BITS).o
 obj-$(CONFIG_KEXEC_CORE)	+= machine_kexec_$(BITS).o
 obj-$(CONFIG_KEXEC_CORE)	+= relocate_kernel_$(BITS).o crash.o

arch/x86/kernel/trace.c

···
+#include <asm/trace/irq_vectors.h>
+#include <linux/trace.h>
+
+#if defined(CONFIG_OSNOISE_TRACER) && defined(CONFIG_X86_LOCAL_APIC)
+/*
+ * trace_intel_irq_entry - record intel specific IRQ entry
+ */
+static void trace_intel_irq_entry(void *data, int vector)
+{
+	osnoise_trace_irq_entry(vector);
+}
+
+/*
+ * trace_intel_irq_exit - record intel specific IRQ exit
+ */
+static void trace_intel_irq_exit(void *data, int vector)
+{
+	char *vector_desc = (char *) data;
+
+	osnoise_trace_irq_exit(vector, vector_desc);
+}
+
+/*
+ * register_intel_irq_tp - Register intel specific IRQ entry tracepoints
+ */
+int osnoise_arch_register(void)
+{
+	int ret;
+
+	ret = register_trace_local_timer_entry(trace_intel_irq_entry, NULL);
+	if (ret)
+		goto out_err;
+
+	ret = register_trace_local_timer_exit(trace_intel_irq_exit, "local_timer");
+	if (ret)
+		goto out_timer_entry;
+
+#ifdef CONFIG_X86_THERMAL_VECTOR
+	ret = register_trace_thermal_apic_entry(trace_intel_irq_entry, NULL);
+	if (ret)
+		goto out_timer_exit;
+
+	ret = register_trace_thermal_apic_exit(trace_intel_irq_exit, "thermal_apic");
+	if (ret)
+		goto out_thermal_entry;
+#endif /* CONFIG_X86_THERMAL_VECTOR */
+
+#ifdef CONFIG_X86_MCE_AMD
+	ret = register_trace_deferred_error_apic_entry(trace_intel_irq_entry, NULL);
+	if (ret)
+		goto out_thermal_exit;
+
+	ret = register_trace_deferred_error_apic_exit(trace_intel_irq_exit, "deferred_error");
+	if (ret)
+		goto out_deferred_entry;
+#endif
+
+#ifdef CONFIG_X86_MCE_THRESHOLD
+	ret = register_trace_threshold_apic_entry(trace_intel_irq_entry, NULL);
+	if (ret)
+		goto out_deferred_exit;
+
+	ret = register_trace_threshold_apic_exit(trace_intel_irq_exit, "threshold_apic");
+	if (ret)
+		goto out_threshold_entry;
+#endif /* CONFIG_X86_MCE_THRESHOLD */
+
+#ifdef CONFIG_SMP
+	ret = register_trace_call_function_single_entry(trace_intel_irq_entry, NULL);
+	if (ret)
+		goto out_threshold_exit;
+
+	ret = register_trace_call_function_single_exit(trace_intel_irq_exit,
+						       "call_function_single");
+	if (ret)
+		goto out_call_function_single_entry;
+
+	ret = register_trace_call_function_entry(trace_intel_irq_entry, NULL);
+	if (ret)
+		goto out_call_function_single_exit;
+
+	ret = register_trace_call_function_exit(trace_intel_irq_exit, "call_function");
+	if (ret)
+		goto out_call_function_entry;
+
+	ret = register_trace_reschedule_entry(trace_intel_irq_entry, NULL);
+	if (ret)
+		goto out_call_function_exit;
+
+	ret = register_trace_reschedule_exit(trace_intel_irq_exit, "reschedule");
+	if (ret)
+		goto out_reschedule_entry;
+#endif /* CONFIG_SMP */
+
+#ifdef CONFIG_IRQ_WORK
+	ret = register_trace_irq_work_entry(trace_intel_irq_entry, NULL);
+	if (ret)
+		goto out_reschedule_exit;
+
+	ret = register_trace_irq_work_exit(trace_intel_irq_exit, "irq_work");
+	if (ret)
+		goto out_irq_work_entry;
+#endif
+
+	ret = register_trace_x86_platform_ipi_entry(trace_intel_irq_entry, NULL);
+	if (ret)
+		goto out_irq_work_exit;
+
+	ret = register_trace_x86_platform_ipi_exit(trace_intel_irq_exit, "x86_platform_ipi");
+	if (ret)
+		goto out_x86_ipi_entry;
+
+	ret = register_trace_error_apic_entry(trace_intel_irq_entry, NULL);
+	if (ret)
+		goto out_x86_ipi_exit;
+
+	ret = register_trace_error_apic_exit(trace_intel_irq_exit, "error_apic");
+	if (ret)
+		goto out_error_apic_entry;
+
+	ret = register_trace_spurious_apic_entry(trace_intel_irq_entry, NULL);
+	if (ret)
+		goto out_error_apic_exit;
+
+	ret = register_trace_spurious_apic_exit(trace_intel_irq_exit, "spurious_apic");
+	if (ret)
+		goto out_spurious_apic_entry;
+
+	return 0;
+
+out_spurious_apic_entry:
+	unregister_trace_spurious_apic_entry(trace_intel_irq_entry, NULL);
+out_error_apic_exit:
+	unregister_trace_error_apic_exit(trace_intel_irq_exit, "error_apic");
+out_error_apic_entry:
+	unregister_trace_error_apic_entry(trace_intel_irq_entry, NULL);
+out_x86_ipi_exit:
+	unregister_trace_x86_platform_ipi_exit(trace_intel_irq_exit, "x86_platform_ipi");
+out_x86_ipi_entry:
+	unregister_trace_x86_platform_ipi_entry(trace_intel_irq_entry, NULL);
+out_irq_work_exit:
+
+#ifdef CONFIG_IRQ_WORK
+	unregister_trace_irq_work_exit(trace_intel_irq_exit, "irq_work");
+out_irq_work_entry:
+	unregister_trace_irq_work_entry(trace_intel_irq_entry, NULL);
+out_reschedule_exit:
+#endif
+
+#ifdef CONFIG_SMP
+	unregister_trace_reschedule_exit(trace_intel_irq_exit, "reschedule");
+out_reschedule_entry:
+	unregister_trace_reschedule_entry(trace_intel_irq_entry, NULL);
+out_call_function_exit:
+	unregister_trace_call_function_exit(trace_intel_irq_exit, "call_function");
+out_call_function_entry:
+	unregister_trace_call_function_entry(trace_intel_irq_entry, NULL);
+out_call_function_single_exit:
+	unregister_trace_call_function_single_exit(trace_intel_irq_exit, "call_function_single");
+out_call_function_single_entry:
+	unregister_trace_call_function_single_entry(trace_intel_irq_entry, NULL);
+out_threshold_exit:
+#endif
+
+#ifdef CONFIG_X86_MCE_THRESHOLD
+	unregister_trace_threshold_apic_exit(trace_intel_irq_exit, "threshold_apic");
+out_threshold_entry:
+	unregister_trace_threshold_apic_entry(trace_intel_irq_entry, NULL);
+out_deferred_exit:
+#endif
+
+#ifdef CONFIG_X86_MCE_AMD
+	unregister_trace_deferred_error_apic_exit(trace_intel_irq_exit, "deferred_error");
+out_deferred_entry:
+	unregister_trace_deferred_error_apic_entry(trace_intel_irq_entry, NULL);
+out_thermal_exit:
+#endif /* CONFIG_X86_MCE_AMD */
+
+#ifdef CONFIG_X86_THERMAL_VECTOR
+	unregister_trace_thermal_apic_exit(trace_intel_irq_exit, "thermal_apic");
+out_thermal_entry:
+	unregister_trace_thermal_apic_entry(trace_intel_irq_entry, NULL);
+out_timer_exit:
+#endif /* CONFIG_X86_THERMAL_VECTOR */
+
+	unregister_trace_local_timer_exit(trace_intel_irq_exit, "local_timer");
+out_timer_entry:
+	unregister_trace_local_timer_entry(trace_intel_irq_entry, NULL);
+out_err:
+	return -EINVAL;
+}
+
+void osnoise_arch_unregister(void)
+{
+	unregister_trace_spurious_apic_exit(trace_intel_irq_exit, "spurious_apic");
+	unregister_trace_spurious_apic_entry(trace_intel_irq_entry, NULL);
+	unregister_trace_error_apic_exit(trace_intel_irq_exit, "error_apic");
+	unregister_trace_error_apic_entry(trace_intel_irq_entry, NULL);
+	unregister_trace_x86_platform_ipi_exit(trace_intel_irq_exit, "x86_platform_ipi");
+	unregister_trace_x86_platform_ipi_entry(trace_intel_irq_entry, NULL);
+
+#ifdef CONFIG_IRQ_WORK
+	unregister_trace_irq_work_exit(trace_intel_irq_exit, "irq_work");
+	unregister_trace_irq_work_entry(trace_intel_irq_entry, NULL);
+#endif
+
+#ifdef CONFIG_SMP
+	unregister_trace_reschedule_exit(trace_intel_irq_exit, "reschedule");
+	unregister_trace_reschedule_entry(trace_intel_irq_entry, NULL);
+	unregister_trace_call_function_exit(trace_intel_irq_exit, "call_function");
+	unregister_trace_call_function_entry(trace_intel_irq_entry, NULL);
+	unregister_trace_call_function_single_exit(trace_intel_irq_exit, "call_function_single");
+	unregister_trace_call_function_single_entry(trace_intel_irq_entry, NULL);
+#endif
+
+#ifdef CONFIG_X86_MCE_THRESHOLD
+	unregister_trace_threshold_apic_exit(trace_intel_irq_exit, "threshold_apic");
+	unregister_trace_threshold_apic_entry(trace_intel_irq_entry, NULL);
+#endif
+
+#ifdef CONFIG_X86_MCE_AMD
+	unregister_trace_deferred_error_apic_exit(trace_intel_irq_exit, "deferred_error");
+	unregister_trace_deferred_error_apic_entry(trace_intel_irq_entry, NULL);
+#endif
+
+#ifdef CONFIG_X86_THERMAL_VECTOR
+	unregister_trace_thermal_apic_exit(trace_intel_irq_exit, "thermal_apic");
+	unregister_trace_thermal_apic_entry(trace_intel_irq_entry, NULL);
+#endif /* CONFIG_X86_THERMAL_VECTOR */
+
+	unregister_trace_local_timer_exit(trace_intel_irq_exit, "local_timer");
+	unregister_trace_local_timer_entry(trace_intel_irq_entry, NULL);
+}
+#endif /* CONFIG_OSNOISE_TRAECR && CONFIG_X86_LOCAL_APIC */

drivers/gpu/drm/amd/amdgpu/amdgpu_trace.h

···
 
 	    TP_fast_assign(
 			   __entry->sched_job_id = job->base.id;
-			   __assign_str(timeline, AMDGPU_JOB_GET_TIMELINE_NAME(job))
+			   __assign_str(timeline, AMDGPU_JOB_GET_TIMELINE_NAME(job));
 			   __entry->context = job->base.s_fence->finished.context;
 			   __entry->seqno = job->base.s_fence->finished.seqno;
-			   __assign_str(ring, to_amdgpu_ring(job->base.sched)->name)
+			   __assign_str(ring, to_amdgpu_ring(job->base.sched)->name);
 			   __entry->num_ibs = job->num_ibs;
 			   ),
 	    TP_printk("sched_job=%llu, timeline=%s, context=%u, seqno=%u, ring_name=%s, num_ibs=%u",
···
 
 	    TP_fast_assign(
 			   __entry->sched_job_id = job->base.id;
-			   __assign_str(timeline, AMDGPU_JOB_GET_TIMELINE_NAME(job))
+			   __assign_str(timeline, AMDGPU_JOB_GET_TIMELINE_NAME(job));
 			   __entry->context = job->base.s_fence->finished.context;
 			   __entry->seqno = job->base.s_fence->finished.seqno;
-			   __assign_str(ring, to_amdgpu_ring(job->base.sched)->name)
+			   __assign_str(ring, to_amdgpu_ring(job->base.sched)->name);
 			   __entry->num_ibs = job->num_ibs;
 			   ),
 	    TP_printk("sched_job=%llu, timeline=%s, context=%u, seqno=%u, ring_name=%s, num_ibs=%u",
···
 
 	    TP_fast_assign(
 			   __entry->pasid = vm->pasid;
-			   __assign_str(ring, ring->name)
+			   __assign_str(ring, ring->name);
 			   __entry->vmid = job->vmid;
 			   __entry->vm_hub = ring->funcs->vmhub,
 			   __entry->pd_addr = job->vm_pd_addr;
···
 			     ),
 
 	    TP_fast_assign(
-			   __assign_str(ring, ring->name)
+			   __assign_str(ring, ring->name);
 			   __entry->vmid = vmid;
 			   __entry->vm_hub = ring->funcs->vmhub;
 			   __entry->pd_addr = pd_addr;
···
 			     ),
 
 	    TP_fast_assign(
-			   __assign_str(ring, sched_job->base.sched->name)
+			   __assign_str(ring, sched_job->base.sched->name);
 			   __entry->id = sched_job->base.id;
 			   __entry->fence = fence;
 			   __entry->ctx = fence->context;

drivers/gpu/drm/lima/lima_trace.h

···
 		__entry->task_id = task->base.id;
 		__entry->context = task->base.s_fence->finished.context;
 		__entry->seqno = task->base.s_fence->finished.seqno;
-		__assign_str(pipe, task->base.sched->name)
+		__assign_str(pipe, task->base.sched->name);
 		),
 
 	TP_printk("task=%llu, context=%u seqno=%u pipe=%s",

drivers/infiniband/hw/hfi1/trace_misc.h

···
 			     __array(char, buf, 64)
 			     __field(int, src)
 			     ),
-	    TP_fast_assign(DD_DEV_ASSIGN(dd)
+	    TP_fast_assign(DD_DEV_ASSIGN(dd);
 			   is_entry->is_name(__entry->buf, 64,
 					     src - is_entry->start);
 			   __entry->src = src;
···
 			     __field(u32, qpn)
 			     __field(u8, opcode)
 			     ),
-	    TP_fast_assign(DD_DEV_ASSIGN(dd_from_ibdev(qp->ibqp.device))
+	    TP_fast_assign(DD_DEV_ASSIGN(dd_from_ibdev(qp->ibqp.device));
 			   __entry->qpn = qp->ibqp.qp_num;
 			   __entry->opcode = opcode;
 			   ),

drivers/infiniband/hw/hfi1/trace_rc.h

···
 			__field(u32, r_psn)
 			),
 		    TP_fast_assign(
-			DD_DEV_ASSIGN(dd_from_ibdev(qp->ibqp.device))
+			DD_DEV_ASSIGN(dd_from_ibdev(qp->ibqp.device));
 			__entry->qpn = qp->ibqp.qp_num;
 			__entry->s_flags = qp->s_flags;
 			__entry->psn = psn;
···
 		__field(u32, lpsn)
 	),
 	TP_fast_assign(/* assign */
-		DD_DEV_ASSIGN(dd_from_ibdev(qp->ibqp.device))
+		DD_DEV_ASSIGN(dd_from_ibdev(qp->ibqp.device));
 		__entry->qpn = qp->ibqp.qp_num;
 		__entry->aeth = aeth;
 		__entry->psn = psn;

drivers/infiniband/hw/hfi1/trace_tid.h

···
 		__field(u8, s_retry)
 	),
 	TP_fast_assign(/* assign */
-		DD_DEV_ASSIGN(dd_from_ibdev(qp->ibqp.device))
+		DD_DEV_ASSIGN(dd_from_ibdev(qp->ibqp.device));
 		__entry->qpn = qp->ibqp.qp_num;
 		__entry->state = qp->state;
 		__entry->s_cur = qp->s_cur;
···
 		__field(int, diff)
 	),
 	TP_fast_assign(/* assign */
-		DD_DEV_ASSIGN(dd_from_ibdev(qp->ibqp.device))
+		DD_DEV_ASSIGN(dd_from_ibdev(qp->ibqp.device));
 		__entry->qpn = qp->ibqp.qp_num;
 		__entry->s_flags = qp->s_flags;
 		__entry->state = qp->state;
···
 		__field(u32, resync_psn)
 	),
 	TP_fast_assign(/* assign */
-		DD_DEV_ASSIGN(dd_from_ibdev(qp->ibqp.device))
+		DD_DEV_ASSIGN(dd_from_ibdev(qp->ibqp.device));
 		__entry->qpn = qp->ibqp.qp_num;
 		__entry->aeth = aeth;
 		__entry->psn = psn;

drivers/infiniband/hw/hfi1/trace_tx.h

···
 		    __field(unsigned long, iow_flags)
 		    ),
 		    TP_fast_assign(
-		    DD_DEV_ASSIGN(dd_from_ibdev(qp->ibqp.device))
+		    DD_DEV_ASSIGN(dd_from_ibdev(qp->ibqp.device));
 		    __entry->flags = flags;
 		    __entry->qpn = qp->ibqp.qp_num;
 		    __entry->s_flags = qp->s_flags;
···
 		__field(int, send_flags)
 	),
 	TP_fast_assign(
-		DD_DEV_ASSIGN(dd_from_ibdev(qp->ibqp.device))
+		DD_DEV_ASSIGN(dd_from_ibdev(qp->ibqp.device));
 		__entry->wqe = wqe;
 		__entry->wr_id = wqe->wr.wr_id;
 		__entry->qpn = qp->ibqp.qp_num;
···
 		__field(bool, flag)
 	),
 	TP_fast_assign(
-		DD_DEV_ASSIGN(dd_from_ibdev(qp->ibqp.device))
+		DD_DEV_ASSIGN(dd_from_ibdev(qp->ibqp.device));
 		__entry->qpn = qp->ibqp.qp_num;
 		__entry->flag = flag;
 	),
···
 		__field(u8, stopped)
 	),
 	TP_fast_assign(/* assign */
-		DD_DEV_ASSIGN(txq->priv->dd)
+		DD_DEV_ASSIGN(txq->priv->dd);
 		__entry->txq = txq;
 		__entry->sde = txq->sde;
 		__entry->head = txq->tx_ring.head;

drivers/infiniband/sw/rdmavt/trace_cq.h

···
 				     __field(int, comp_vector_cpu)
 				     __field(u32, flags)
 				     ),
-		    TP_fast_assign(RDI_DEV_ASSIGN(cq->rdi)
+		    TP_fast_assign(RDI_DEV_ASSIGN(cq->rdi);
 				   __entry->ip = cq->ip;
 				   __entry->cqe = attr->cqe;
 				   __entry->comp_vector = attr->comp_vector;
···
 		__field(u32, imm)
 	),
 	TP_fast_assign(
-		RDI_DEV_ASSIGN(cq->rdi)
+		RDI_DEV_ASSIGN(cq->rdi);
 		__entry->wr_id = wc->wr_id;
 		__entry->status = wc->status;
 		__entry->opcode = wc->opcode;

drivers/infiniband/sw/rdmavt/trace_mr.h

···
 		__field(uint, sg_offset)
 	),
 	TP_fast_assign(
-		RDI_DEV_ASSIGN(ib_to_rvt(to_imr(ibmr)->mr.pd->device))
+		RDI_DEV_ASSIGN(ib_to_rvt(to_imr(ibmr)->mr.pd->device));
 		__entry->ibmr_iova = ibmr->iova;
 		__entry->iova = to_imr(ibmr)->mr.iova;
 		__entry->user_base = to_imr(ibmr)->mr.user_base;

drivers/infiniband/sw/rdmavt/trace_qp.h

···
 		__field(u32, bucket)
 	),
 	TP_fast_assign(
-		RDI_DEV_ASSIGN(ib_to_rvt(qp->ibqp.device))
+		RDI_DEV_ASSIGN(ib_to_rvt(qp->ibqp.device));
 		__entry->qpn = qp->ibqp.qp_num;
 		__entry->bucket = bucket;
 	),
···
 		__field(u32, to)
 	),
 	TP_fast_assign(
-		RDI_DEV_ASSIGN(ib_to_rvt(qp->ibqp.device))
+		RDI_DEV_ASSIGN(ib_to_rvt(qp->ibqp.device));
 		__entry->qpn = qp->ibqp.qp_num;
 		__entry->hrtimer = &qp->s_rnr_timer;
 		__entry->s_flags = qp->s_flags;

drivers/infiniband/sw/rdmavt/trace_rc.h

···
 			__field(u32, r_psn)
 			),
 		    TP_fast_assign(
-			RDI_DEV_ASSIGN(ib_to_rvt(qp->ibqp.device))
+			RDI_DEV_ASSIGN(ib_to_rvt(qp->ibqp.device));
 			__entry->qpn = qp->ibqp.qp_num;
 			__entry->s_flags = qp->s_flags;
 			__entry->psn = psn;

drivers/infiniband/sw/rdmavt/trace_tx.h

···
 		__field(int, wr_num_sge)
 	),
 	TP_fast_assign(
-		RDI_DEV_ASSIGN(ib_to_rvt(qp->ibqp.device))
+		RDI_DEV_ASSIGN(ib_to_rvt(qp->ibqp.device));
 		__entry->wqe = wqe;
 		__entry->wr_id = wqe->wr.wr_id;
 		__entry->qpn = qp->ibqp.qp_num;
···
 		__field(int, send_flags)
 	),
 	TP_fast_assign(
-		RDI_DEV_ASSIGN(ib_to_rvt(qp->ibqp.device))
+		RDI_DEV_ASSIGN(ib_to_rvt(qp->ibqp.device));
 		__entry->wqe = wqe;
 		__entry->wr_id = wqe->wr.wr_id;
 		__entry->qpn = qp->ibqp.qp_num;

drivers/misc/mei/mei-trace.h

···
 		__field(u32, val)
 	),
 	TP_fast_assign(
-		__assign_str(dev, dev_name(dev))
+		__assign_str(dev, dev_name(dev));
 		__entry->reg  = reg;
 		__entry->offs = offs;
 		__entry->val = val;
···
 		__field(u32, val)
 	),
 	TP_fast_assign(
-		__assign_str(dev, dev_name(dev))
+		__assign_str(dev, dev_name(dev));
 		__entry->reg = reg;
 		__entry->offs = offs;
 		__entry->val = val;
···
 		__field(u32, val)
 	),
 	TP_fast_assign(
-		__assign_str(dev, dev_name(dev))
+		__assign_str(dev, dev_name(dev));
 		__entry->reg  = reg;
 		__entry->offs = offs;
 		__entry->val = val;

drivers/net/ethernet/marvell/octeontx2/af/rvu_trace.h

···
 			     __field(u16, id)
 			     __field(u64, size)
 	    ),
-	    TP_fast_assign(__assign_str(dev, pci_name(pdev))
+	    TP_fast_assign(__assign_str(dev, pci_name(pdev));
 			   __entry->id = id;
 			   __entry->size = size;
 	    ),
···
 			     __field(u16, num_msgs)
 			     __field(u64, msg_size)
 	    ),
-	    TP_fast_assign(__assign_str(dev, pci_name(pdev))
+	    TP_fast_assign(__assign_str(dev, pci_name(pdev));
 			   __entry->num_msgs = num_msgs;
 			   __entry->msg_size = msg_size;
 	    ),
···
 			     __field(u16, rspid)
 			     __field(int, rc)
 	    ),
-	    TP_fast_assign(__assign_str(dev, pci_name(pdev))
+	    TP_fast_assign(__assign_str(dev, pci_name(pdev));
 			   __entry->reqid = reqid;
 			   __entry->rspid = rspid;
 			   __entry->rc = rc;
···
 			     __string(str, msg)
 			     __field(u64, intr)
 	    ),
-	    TP_fast_assign(__assign_str(dev, pci_name(pdev))
-			   __assign_str(str, msg)
+	    TP_fast_assign(__assign_str(dev, pci_name(pdev));
+			   __assign_str(str, msg);
 			   __entry->intr = intr;
 	    ),
 	    TP_printk("[%s] mbox interrupt %s (0x%llx)\n", __get_str(dev),
···
 			     __field(u16, id)
 			     __field(int, err)
 	    ),
-	    TP_fast_assign(__assign_str(dev, pci_name(pdev))
+	    TP_fast_assign(__assign_str(dev, pci_name(pdev));
 			   __entry->id = id;
 			   __entry->err = err;
 	    ),

drivers/net/fjes/fjes_trace.h

···
 		 __string(err, err)
 	),
 	TP_fast_assign(
-		__assign_str(err, err)
+		__assign_str(err, err);
 	),
 	TP_printk("%s", __get_str(err))
 );
···
 		 __string(err, err)
 	),
 	TP_fast_assign(
-		__assign_str(err, err)
+		__assign_str(err, err);
 	),
 	TP_printk("%s", __get_str(err))
 );

drivers/usb/cdns3/cdnsp-trace.h

···
 		__string(text, msg)
 	),
 	TP_fast_assign(
-		__assign_str(text, msg)
+		__assign_str(text, msg);
 	),
 	TP_printk("%s", __get_str(text))
 );

fs/nfs/nfs4trace.h

···
 
 		TP_fast_assign(
 			__entry->state = clp->cl_state;
-			__assign_str(hostname, clp->cl_hostname)
+			__assign_str(hostname, clp->cl_hostname);
 		),
 
 		TP_printk(
···
 				__entry->fileid = 0;
 				__entry->dev = 0;
 			}
-			__assign_str(dstaddr, clp ? clp->cl_hostname : "unknown")
+			__assign_str(dstaddr, clp ? clp->cl_hostname : "unknown");
 		),
 
 		TP_printk(
···
 				__entry->fileid = 0;
 				__entry->dev = 0;
 			}
-			__assign_str(dstaddr, clp ? clp->cl_hostname : "unknown")
+			__assign_str(dstaddr, clp ? clp->cl_hostname : "unknown");
 			__entry->stateid_seq =
 				be32_to_cpu(stateid->seqid);
 			__entry->stateid_hash =

fs/nfs/nfstrace.h

···
 			__entry->version = task->tk_client->cl_vers;
 			__entry->error = error;
 			__assign_str(program,
-				     task->tk_client->cl_program->name)
-			__assign_str(procedure, task->tk_msg.rpc_proc->p_name)
+				     task->tk_client->cl_program->name);
+			__assign_str(procedure, task->tk_msg.rpc_proc->p_name);
 		),
 
 		TP_printk(

fs/proc/bootconfig.c

···
 				else
 					q = '"';
 				ret = snprintf(dst, rest(dst, end), "%c%s%c%s",
-					q, val, q, vnode->next ? ", " : "\n");
+					q, val, q, xbc_node_is_array(vnode) ? ", " : "\n");
 				if (ret < 0)
 					goto out;
 				dst += ret;

include/linux/bootconfig.h

···
 #define BOOTCONFIG_ALIGN	(1 << BOOTCONFIG_ALIGN_SHIFT)
 #define BOOTCONFIG_ALIGN_MASK	(BOOTCONFIG_ALIGN - 1)
 
+/**
+ * xbc_calc_checksum() - Calculate checksum of bootconfig
+ * @data: Bootconfig data.
+ * @size: The size of the bootconfig data.
+ *
+ * Calculate the checksum value of the bootconfig data.
+ * The checksum will be used with the BOOTCONFIG_MAGIC and the size for
+ * embedding the bootconfig in the initrd image.
+ */
+static inline __init u32 xbc_calc_checksum(void *data, u32 size)
+{
+	unsigned char *p = data;
+	u32 ret = 0;
+
+	while (size--)
+		ret += *p++;
+
+	return ret;
+}
+
 /* XBC tree node */
 struct xbc_node {
 	u16 next;
···
  */
 static inline __init bool xbc_node_is_array(struct xbc_node *node)
 {
-	return xbc_node_is_value(node) && node->next != 0;
+	return xbc_node_is_value(node) && node->child != 0;
 }
 
 /**
···
  *
  * Test the @node is a leaf key node which is a key node and has a value node
  * or no child. Returns true if it is a leaf node, or false if not.
+ * Note that the leaf node can have subkey nodes in addition to the
+ * value node.
  */
 static inline __init bool xbc_node_is_leaf(struct xbc_node *node)
 {
···
 }
 
 /**
+ * xbc_node_get_subkey() - Return the first subkey node if exists
+ * @node: Parent node
+ *
+ * Return the first subkey node of the @node. If the @node has no child
+ * or only value node, this will return NULL.
+ */
+static inline struct xbc_node * __init xbc_node_get_subkey(struct xbc_node *node)
+{
+	struct xbc_node *child = xbc_node_get_child(node);
+
+	if (child && xbc_node_is_value(child))
+		return xbc_node_get_next(child);
+	else
+		return child;
+}
+
+/**
  * xbc_array_for_each_value() - Iterate value nodes on an array
  * @anode: An XBC arraied value node
  * @value: A value
···
  */
 #define xbc_array_for_each_value(anode, value)				\
 	for (value = xbc_node_get_data(anode); anode != NULL ;		\
-	     anode = xbc_node_get_next(anode),				\
+	     anode = xbc_node_get_child(anode),				\
 	     value = anode ? xbc_node_get_data(anode) : NULL)
 
 /**
···
  * @child: Iterated XBC node.
  *
  * Iterate child nodes of @parent. Each child nodes are stored to @child.
+ * The @child can be mixture of a value node and subkey nodes.
  */
 #define xbc_node_for_each_child(parent, child)				\
 	for (child = xbc_node_get_child(parent); child != NULL ;	\
+	     child = xbc_node_get_next(child))
+
+/**
+ * xbc_node_for_each_subkey() - Iterate child subkey nodes
+ * @parent: An XBC node.
+ * @child: Iterated XBC node.
+ *
+ * Iterate subkey nodes of @parent. Each child nodes are stored to @child.
+ * The @child is only the subkey node.
+ */
+#define xbc_node_for_each_subkey(parent, child)				\
+	for (child = xbc_node_get_subkey(parent); child != NULL ;	\
 	     child = xbc_node_get_next(child))
 
 /**
···
  */
 #define xbc_node_for_each_array_value(node, key, anode, value)		\
 	for (value = xbc_node_find_value(node, key, &anode); value != NULL; \
-	     anode = xbc_node_get_next(anode),				\
+	     anode = xbc_node_get_child(anode),				\
 	     value = anode ? xbc_node_get_data(anode) : NULL)
 
 /**

include/linux/ftrace_irq.h

···
 extern void trace_hwlat_callback(bool enter);
 #endif
 
+#ifdef CONFIG_OSNOISE_TRACER
+extern bool trace_osnoise_callback_enabled;
+extern void trace_osnoise_callback(bool enter);
+#endif
+
 static inline void ftrace_nmi_enter(void)
 {
 #ifdef CONFIG_HWLAT_TRACER
 	if (trace_hwlat_callback_enabled)
 		trace_hwlat_callback(true);
+#endif
+#ifdef CONFIG_OSNOISE_TRACER
+	if (trace_osnoise_callback_enabled)
+		trace_osnoise_callback(true);
 #endif
 }
 
···
 #ifdef CONFIG_HWLAT_TRACER
 	if (trace_hwlat_callback_enabled)
 		trace_hwlat_callback(false);
+#endif
+#ifdef CONFIG_OSNOISE_TRACER
+	if (trace_osnoise_callback_enabled)
+		trace_osnoise_callback(false);
 #endif
 }
 

include/linux/trace.h

···
 void trace_array_put(struct trace_array *tr);
 struct trace_array *trace_array_get_by_name(const char *name);
 int trace_array_destroy(struct trace_array *tr);
+
+/* For osnoise tracer */
+int osnoise_arch_register(void);
+void osnoise_arch_unregister(void);
+void osnoise_trace_irq_entry(int id);
+void osnoise_trace_irq_exit(int id, const char *desc);
+
 #endif	/* CONFIG_TRACING */
 
 #endif	/* _LINUX_TRACE_H */

include/linux/tracepoint.h

···
 tracepoint_probe_register_prio(struct tracepoint *tp, void *probe, void *data,
 			       int prio);
 extern int
+tracepoint_probe_register_prio_may_exist(struct tracepoint *tp, void *probe, void *data,
+					 int prio);
+extern int
 tracepoint_probe_unregister(struct tracepoint *tp, void *probe, void *data);
+static inline int
+tracepoint_probe_register_may_exist(struct tracepoint *tp, void *probe,
+				    void *data)
+{
+	return tracepoint_probe_register_prio_may_exist(tp, probe, data,
+							TRACEPOINT_DEFAULT_PRIO);
+}
 extern void
 for_each_kernel_tracepoint(void (*fct)(struct tracepoint *tp, void *priv),
 		void *priv);

include/trace/events/btrfs.h

···
 		__entry->flags	= flags;
 		__entry->bytes	= bytes;
 		__entry->flush	= flush;
-		__assign_str(reason, reason)
+		__assign_str(reason, reason);
 	),
 
 	TP_printk_btrfs("%s: flush=%d(%s) flags=%llu(%s) bytes=%llu",

include/trace/events/dma_fence.h

···
 	),
 
 	TP_fast_assign(
-		__assign_str(driver, fence->ops->get_driver_name(fence))
-		__assign_str(timeline, fence->ops->get_timeline_name(fence))
+		__assign_str(driver, fence->ops->get_driver_name(fence));
+		__assign_str(timeline, fence->ops->get_timeline_name(fence));
 		__entry->context = fence->context;
 		__entry->seqno = fence->seqno;
 	),

include/trace/events/osnoise.h

···
+/* SPDX-License-Identifier: GPL-2.0 */
+#undef TRACE_SYSTEM
+#define TRACE_SYSTEM osnoise
+
+#if !defined(_OSNOISE_TRACE_H) || defined(TRACE_HEADER_MULTI_READ)
+#define _OSNOISE_TRACE_H
+
+#include <linux/tracepoint.h>
+TRACE_EVENT(thread_noise,
+
+	TP_PROTO(struct task_struct *t, u64 start, u64 duration),
+
+	TP_ARGS(t, start, duration),
+
+	TP_STRUCT__entry(
+		__array(	char,		comm,	TASK_COMM_LEN)
+		__field(	u64,		start	)
+		__field(	u64,		duration)
+		__field(	pid_t,		pid	)
+	),
+
+	TP_fast_assign(
+		memcpy(__entry->comm, t->comm, TASK_COMM_LEN);
+		__entry->pid = t->pid;
+		__entry->start = start;
+		__entry->duration = duration;
+	),
+
+	TP_printk("%8s:%d start %llu.%09u duration %llu ns",
+		__entry->comm,
+		__entry->pid,
+		__print_ns_to_secs(__entry->start),
+		__print_ns_without_secs(__entry->start),
+		__entry->duration)
+);
+
+TRACE_EVENT(softirq_noise,
+
+	TP_PROTO(int vector, u64 start, u64 duration),
+
+	TP_ARGS(vector, start, duration),
+
+	TP_STRUCT__entry(
+		__field(	u64,		start	)
+		__field(	u64,		duration)
+		__field(	int,		vector	)
+	),
+
+	TP_fast_assign(
+		__entry->vector = vector;
+		__entry->start = start;
+		__entry->duration = duration;
+	),
+
+	TP_printk("%8s:%d start %llu.%09u duration %llu ns",
+		show_softirq_name(__entry->vector),
+		__entry->vector,
+		__print_ns_to_secs(__entry->start),
+		__print_ns_without_secs(__entry->start),
+		__entry->duration)
+);
+
+TRACE_EVENT(irq_noise,
+
+	TP_PROTO(int vector, const char *desc, u64 start, u64 duration),
+
+	TP_ARGS(vector, desc, start, duration),
+
+	TP_STRUCT__entry(
+		__field(	u64,		start	)
+		__field(	u64,		duration)
+		__string(	desc,		desc    )
+		__field(	int,		vector	)
+
+	),
+
+	TP_fast_assign(
+		__assign_str(desc, desc);
+		__entry->vector = vector;
+		__entry->start = start;
+		__entry->duration = duration;
+	),
+
+	TP_printk("%s:%d start %llu.%09u duration %llu ns",
+		__get_str(desc),
+		__entry->vector,
+		__print_ns_to_secs(__entry->start),
+		__print_ns_without_secs(__entry->start),
+		__entry->duration)
+);
+
+TRACE_EVENT(nmi_noise,
+
+	TP_PROTO(u64 start, u64 duration),
+
+	TP_ARGS(start, duration),
+
+	TP_STRUCT__entry(
+		__field(	u64,		start	)
+		__field(	u64,		duration)
+	),
+
+	TP_fast_assign(
+		__entry->start = start;
+		__entry->duration = duration;
+	),
+
+	TP_printk("start %llu.%09u duration %llu ns",
+		__print_ns_to_secs(__entry->start),
+		__print_ns_without_secs(__entry->start),
+		__entry->duration)
+);
+
+TRACE_EVENT(sample_threshold,
+
+	TP_PROTO(u64 start, u64 duration, u64 interference),
+
+	TP_ARGS(start, duration, interference),
+
+	TP_STRUCT__entry(
+		__field(	u64,		start	)
+		__field(	u64,		duration)
+		__field(	u64,		interference)
+	),
+
+	TP_fast_assign(
+		__entry->start = start;
+		__entry->duration = duration;
+		__entry->interference = interference;
+	),
+
+	TP_printk("start %llu.%09u duration %llu ns interference %llu",
+		__print_ns_to_secs(__entry->start),
+		__print_ns_without_secs(__entry->start),
+		__entry->duration,
+		__entry->interference)
+);
+
+#endif /* _TRACE_OSNOISE_H */
+
+/* This part must be outside protection */
+#include <trace/define_trace.h>

include/trace/events/rpcgss.h

···
 	TP_fast_assign(
 		__entry->cred = gc;
 		__entry->service = gc->gc_service;
-		__assign_str(principal, gc->gc_principal)
+		__assign_str(principal, gc->gc_principal);
 	),
 
 	TP_printk("cred=%p service=%s principal='%s'",
···
 	),
 
 	TP_fast_assign(
-		__assign_str(msg, buf)
+		__assign_str(msg, buf);
 	),
 
 	TP_printk("msg='%s'", __get_str(msg))

include/trace/events/sched.h

···
 		__array(	char,	comm,	TASK_COMM_LEN	)
 		__field(	pid_t,	pid			)
 		__field(	int,	prio			)
-		__field(	int,	success			)
 		__field(	int,	target_cpu		)
 	),
 
···
 		memcpy(__entry->comm, p->comm, TASK_COMM_LEN);
 		__entry->pid		= p->pid;
 		__entry->prio		= p->prio; /* XXX SCHED_DEADLINE */
-		__entry->success	= 1; /* rudiment, kill when possible */
 		__entry->target_cpu	= task_cpu(p);
 	),
 

include/trace/events/sunrpc.h

···
 		__entry->client_id = clnt->cl_clid;
 		__assign_str(addr, xprt->address_strings[RPC_DISPLAY_ADDR]);
 		__assign_str(port, xprt->address_strings[RPC_DISPLAY_PORT]);
-		__assign_str(program, program)
-		__assign_str(server, server)
+		__assign_str(program, program);
+		__assign_str(server, server);
 	),
 
 	TP_printk("client=%u peer=[%s]:%s program=%s server=%s",
···
 
 	TP_fast_assign(
 		__entry->error = error;
-		__assign_str(program, program)
-		__assign_str(server, server)
+		__assign_str(program, program);
+		__assign_str(server, server);
 	),
 
 	TP_printk("program=%s server=%s error=%d",
···
 		__entry->client_id = task->tk_client->cl_clid;
 		__entry->version = task->tk_client->cl_vers;
 		__entry->async = RPC_IS_ASYNC(task);
-		__assign_str(progname, task->tk_client->cl_program->name)
-		__assign_str(procname, rpc_proc_name(task))
+		__assign_str(progname, task->tk_client->cl_program->name);
+		__assign_str(procname, rpc_proc_name(task));
 	),
 
 	TP_printk("task:%u@%u %sv%d %s (%ssync)",
···
 		__entry->task_id = task->tk_pid;
 		__entry->client_id = task->tk_client->cl_clid;
 		__entry->xid = be32_to_cpu(task->tk_rqstp->rq_xid);
-		__assign_str(progname, task->tk_client->cl_program->name)
+		__assign_str(progname, task->tk_client->cl_program->name);
 		__entry->version = task->tk_client->cl_vers;
-		__assign_str(procname, rpc_proc_name(task))
-		__assign_str(servername, task->tk_xprt->servername)
+		__assign_str(procname, rpc_proc_name(task));
+		__assign_str(servername, task->tk_xprt->servername);
 	),
 
 	TP_printk("task:%u@%d server=%s xid=0x%08x %sv%d %s",
···
 		__entry->task_id = task->tk_pid;
 		__entry->xid = be32_to_cpu(task->tk_rqstp->rq_xid);
 		__entry->version = task->tk_client->cl_vers;
-		__assign_str(progname, task->tk_client->cl_program->name)
-		__assign_str(procname, rpc_proc_name(task))
+		__assign_str(progname, task->tk_client->cl_program->name);
+		__assign_str(procname, rpc_proc_name(task));
 		__entry->backlog = ktime_to_us(backlog);
 		__entry->rtt = ktime_to_us(rtt);
 		__entry->execute = ktime_to_us(execute);
···
 			__entry->task_id = task->tk_pid;
 			__entry->client_id = task->tk_client->cl_clid;
 			__assign_str(progname,
-				     task->tk_client->cl_program->name)
+				     task->tk_client->cl_program->name);
 			__entry->version = task->tk_client->cl_vers;
-			__assign_str(procedure, task->tk_msg.rpc_proc->p_name)
+			__assign_str(procedure, task->tk_msg.rpc_proc->p_name);
 		} else {
 			__entry->task_id = 0;
 			__entry->client_id = 0;
-			__assign_str(progname, "unknown")
+			__assign_str(progname, "unknown");
 			__entry->version = 0;
-			__assign_str(procedure, "unknown")
+			__assign_str(procedure, "unknown");
 		}
 		__entry->requested = requested;
 		__entry->end = xdr->end;
···
 		__entry->task_id = task->tk_pid;
 		__entry->client_id = task->tk_client->cl_clid;
 		__assign_str(progname,
-			     task->tk_client->cl_program->name)
+			     task->tk_client->cl_program->name);
 		__entry->version = task->tk_client->cl_vers;
-		__assign_str(procedure, task->tk_msg.rpc_proc->p_name)
+		__assign_str(procedure, task->tk_msg.rpc_proc->p_name);
 
 		__entry->offset = offset;
 		__entry->copied = copied;
···
 		__entry->xid = be32_to_cpu(rqst->rq_xid);
 		__entry->ntrans = rqst->rq_ntrans;
 		__assign_str(progname,
-			     task->tk_client->cl_program->name)
+			     task->tk_client->cl_program->name);
 		__entry->version = task->tk_client->cl_vers;
-		__assign_str(procedure, task->tk_msg.rpc_proc->p_name)
+		__assign_str(procedure, task->tk_msg.rpc_proc->p_name);
 	),
 
 	TP_printk(
···
 
 	TP_fast_assign(
 		__assign_str(addr, xprt->xpt_remotebuf);
-		__assign_str(protocol, xprt->xpt_class->xcl_name)
+		__assign_str(protocol, xprt->xpt_class->xcl_name);
 		__assign_str(service, service);
 	),
 

include/trace/events/writeback.h

···
 	EM( WB_REASON_PERIODIC,			"periodic")		\
 	EM( WB_REASON_LAPTOP_TIMER,		"laptop_timer")		\
 	EM( WB_REASON_FS_FREE_SPACE,		"fs_free_space")	\
-	EMe(WB_REASON_FORKER_THREAD,		"forker_thread")
+	EM( WB_REASON_FORKER_THREAD,		"forker_thread")	\
+	EMe(WB_REASON_FOREIGN_FLUSH,		"foreign_flush")
 
 WB_WORK_REASON
 

include/trace/trace_events.h

···
 	trace_print_hex_dump_seq(p, prefix_str, prefix_type,		\
 				 rowsize, groupsize, buf, len, ascii)
 
+#undef __print_ns_to_secs
+#define __print_ns_to_secs(value)			\
+	({						\
+		u64 ____val = (u64)(value);		\
+		do_div(____val, NSEC_PER_SEC);		\
+		____val;				\
+	})
+
+#undef __print_ns_without_secs
+#define __print_ns_without_secs(value)			\
+	({						\
+		u64 ____val = (u64)(value);		\
+		(u32) do_div(____val, NSEC_PER_SEC);	\
+	})
+
 #undef DECLARE_EVENT_CLASS
 #define DECLARE_EVENT_CLASS(call, proto, args, tstruct, assign, print)	\
 static notrace enum print_line_t					\
···
 #undef __get_bitmask
 #undef __print_array
 #undef __print_hex_dump
+
+/*
+ * The below is not executed in the kernel. It is only what is
+ * displayed in the print format for userspace to parse.
+ */
+#undef __print_ns_to_secs
+#define __print_ns_to_secs(val) (val) / 1000000000UL
+
+#undef __print_ns_without_secs
+#define __print_ns_without_secs(val) (val) % 1000000000UL
 
 #undef TP_printk
 #define TP_printk(fmt, args...) "\"" fmt "\", "  __stringify(args)

init/main.c

···
 	return new_cmdline;
 }
 
-static u32 boot_config_checksum(unsigned char *p, u32 size)
-{
-	u32 ret = 0;
-
-	while (size--)
-		ret += *p++;
-
-	return ret;
-}
-
 static int __init bootconfig_params(char *param, char *val,
 				    const char *unused, void *arg)
 {
···
 		return;
 	}
 
-	if (boot_config_checksum((unsigned char *)data, size) != csum) {
+	if (xbc_calc_checksum(data, size) != csum) {
 		pr_err("bootconfig checksum failed\n");
 		return;
 	}

kernel/trace/Kconfig

···
 	 file. Every time a latency is greater than tracing_thresh, it will
 	 be recorded into the ring buffer.
 
+config OSNOISE_TRACER
+	bool "OS Noise tracer"
+	select GENERIC_TRACER
+	help
+	  In the context of high-performance computing (HPC), the Operating
+	  System Noise (osnoise) refers to the interference experienced by an
+	  application due to activities inside the operating system. In the
+	  context of Linux, NMIs, IRQs, SoftIRQs, and any other system thread
+	  can cause noise to the system. Moreover, hardware-related jobs can
+	  also cause noise, for example, via SMIs.
+
+	  The osnoise tracer leverages the hwlat_detector by running a similar
+	  loop with preemption, SoftIRQs and IRQs enabled, thus allowing all
+	  the sources of osnoise during its execution. The osnoise tracer takes
+	  note of the entry and exit point of any source of interferences,
+	  increasing a per-cpu interference counter. It saves an interference
+	  counter for each source of interference. The interference counter for
+	  NMI, IRQs, SoftIRQs, and threads is increased anytime the tool
+	  observes these interferences' entry events. When a noise happens
+	  without any interference from the operating system level, the
+	  hardware noise counter increases, pointing to a hardware-related
+	  noise. In this way, osnoise can account for any source of
+	  interference. At the end of the period, the osnoise tracer prints
+	  the sum of all noise, the max single noise, the percentage of CPU
+	  available for the thread, and the counters for the noise sources.
+
+	  In addition to the tracer, a set of tracepoints were added to
+	  facilitate the identification of the osnoise source.
+
+	  The output will appear in the trace and trace_pipe files.
+
+	  To enable this tracer, echo in "osnoise" into the current_tracer
+          file.
+
+config TIMERLAT_TRACER
+	bool "Timerlat tracer"
+	select OSNOISE_TRACER
+	select GENERIC_TRACER
+	help
+	  The timerlat tracer aims to help the preemptive kernel developers
+	  to find sources of wakeup latencies of real-time threads.
+
+	  The tracer creates a per-cpu kernel thread with real-time priority.
+	  The tracer thread sets a periodic timer to wakeup itself, and goes
+	  to sleep waiting for the timer to fire. At the wakeup, the thread
+	  then computes a wakeup latency value as the difference between
+	  the current time and the absolute time that the timer was set
+	  to expire.
+
+	  The tracer prints two lines at every activation. The first is the
+	  timer latency observed at the hardirq context before the
+	  activation of the thread. The second is the timer latency observed
+	  by the thread, which is the same level that cyclictest reports. The
+	  ACTIVATION ID field serves to relate the irq execution to its
+	  respective thread execution.
+
+	  The tracer is build on top of osnoise tracer, and the osnoise:
+	  events can be used to trace the source of interference from NMI,
+	  IRQs and other threads. It also enables the capture of the
+	  stacktrace at the IRQ context, which helps to identify the code
+	  path that can cause thread delay.
+
 config MMIOTRACE
 	bool "Memory mapped IO tracing"
 	depends on HAVE_MMIOTRACE_SUPPORT && PCI

kernel/trace/Makefile

···
 obj-$(CONFIG_PREEMPT_TRACER) += trace_irqsoff.o
 obj-$(CONFIG_SCHED_TRACER) += trace_sched_wakeup.o
 obj-$(CONFIG_HWLAT_TRACER) += trace_hwlat.o
+obj-$(CONFIG_OSNOISE_TRACER) += trace_osnoise.o
 obj-$(CONFIG_NOP_TRACER) += trace_nop.o
 obj-$(CONFIG_STACK_TRACER) += trace_stack.o
 obj-$(CONFIG_MMIOTRACE) += trace_mmiotrace.o

kernel/trace/bpf_trace.c

···
 	if (prog->aux->max_tp_access > btp->writable_size)
 		return -EINVAL;
 
-	return tracepoint_probe_register(tp, (void *)btp->bpf_func, prog);
+	return tracepoint_probe_register_may_exist(tp, (void *)btp->bpf_func,
+						   prog);
 }
 
 int bpf_probe_register(struct bpf_raw_event_map *btp, struct bpf_prog *prog)

kernel/trace/ring_buffer.c

···
 		case RINGBUF_TYPE_PADDING:
 			if (event->time_delta == 1)
 				break;
-			/* fall through */
+			fallthrough;
 		case RINGBUF_TYPE_DATA:
 			ts += event->time_delta;
 			break;

kernel/trace/trace.c

···
 /* Pipe tracepoints to printk */
 struct trace_iterator *tracepoint_print_iter;
 int tracepoint_printk;
+static bool tracepoint_printk_stop_on_boot __initdata;
 static DEFINE_STATIC_KEY_FALSE(tracepoint_printk_key);
 
 /* For tracers that don't implement custom flags */
···
 
 static int __init set_ftrace_dump_on_oops(char *str)
 {
-	if (*str++ != '=' || !*str) {
+	if (*str++ != '=' || !*str || !strcmp("1", str)) {
 		ftrace_dump_on_oops = DUMP_ALL;
 		return 1;
 	}
 
-	if (!strcmp("orig_cpu", str)) {
+	if (!strcmp("orig_cpu", str) || !strcmp("2", str)) {
 		ftrace_dump_on_oops = DUMP_ORIG;
                 return 1;
         }
···
 	return 1;
 }
 __setup("tp_printk", set_tracepoint_printk);
+
+static int __init set_tracepoint_printk_stop(char *str)
+{
+	tracepoint_printk_stop_on_boot = true;
+	return 1;
+}
+__setup("tp_printk_stop_on_boot", set_tracepoint_printk_stop);
 
 unsigned long long ns2usecs(u64 nsec)
 {
···
 unsigned long __read_mostly	tracing_thresh;
 static const struct file_operations tracing_max_lat_fops;
 
-#if (defined(CONFIG_TRACER_MAX_TRACE) || defined(CONFIG_HWLAT_TRACER)) && \
-	defined(CONFIG_FSNOTIFY)
+#ifdef LATENCY_FS_NOTIFY
 
 static struct workqueue_struct *fsnotify_wq;
 
···
 	}
 }
 
+/*
+ * The tgid_map array maps from pid to tgid; i.e. the value stored at index i
+ * is the tgid last observed corresponding to pid=i.
+ */
 static int *tgid_map;
+
+/* The maximum valid index into tgid_map. */
+static size_t tgid_map_max;
 
 #define SAVED_CMDLINES_DEFAULT 128
 #define NO_CMDLINE_MAP UINT_MAX
···
 	preempt_enable();
 }
 
+static int *trace_find_tgid_ptr(int pid)
+{
+	/*
+	 * Pairs with the smp_store_release in set_tracer_flag() to ensure that
+	 * if we observe a non-NULL tgid_map then we also observe the correct
+	 * tgid_map_max.
+	 */
+	int *map = smp_load_acquire(&tgid_map);
+
+	if (unlikely(!map || pid > tgid_map_max))
+		return NULL;
+
+	return &map[pid];
+}
+
 int trace_find_tgid(int pid)
 {
-	if (unlikely(!tgid_map || !pid || pid > PID_MAX_DEFAULT))
-		return 0;
+	int *ptr = trace_find_tgid_ptr(pid);
 
-	return tgid_map[pid];
+	return ptr ? *ptr : 0;
 }
 
 static int trace_save_tgid(struct task_struct *tsk)
 {
+	int *ptr;
+
 	/* treat recording of idle task as a success */
 	if (!tsk->pid)
 		return 1;
 
-	if (unlikely(!tgid_map || tsk->pid > PID_MAX_DEFAULT))
+	ptr = trace_find_tgid_ptr(tsk->pid);
+	if (!ptr)
 		return 0;
 
-	tgid_map[tsk->pid] = tsk->tgid;
+	*ptr = tsk->tgid;
 	return 1;
 }
 
···
 	if (!tr->no_filter_buffering_ref &&
 	    (trace_file->flags & (EVENT_FILE_FL_SOFT_DISABLED | EVENT_FILE_FL_FILTERED)) &&
 	    (entry = this_cpu_read(trace_buffered_event))) {
-		/* Try to use the per cpu buffer first */
+		/*
+		 * Filtering is on, so try to use the per cpu buffer first.
+		 * This buffer will simulate a ring_buffer_event,
+		 * where the type_len is zero and the array[0] will
+		 * hold the full length.
+		 * (see include/linux/ring-buffer.h for details on
+		 *  how the ring_buffer_event is structured).
+		 *
+		 * Using a temp buffer during filtering and copying it
+		 * on a matched filter is quicker than writing directly
+		 * into the ring buffer and then discarding it when
+		 * it doesn't match. That is because the discard
+		 * requires several atomic operations to get right.
+		 * Copying on match and doing nothing on a failed match
+		 * is still quicker than no copy on match, but having
+		 * to discard out of the ring buffer on a failed match.
+		 */
+		int max_len = PAGE_SIZE - struct_size(entry, array, 1);
+
 		val = this_cpu_inc_return(trace_buffered_event_cnt);
-		if ((len < (PAGE_SIZE - sizeof(*entry) - sizeof(entry->array[0]))) && val == 1) {
+
+		/*
+		 * Preemption is disabled, but interrupts and NMIs
+		 * can still come in now. If that happens after
+		 * the above increment, then it will have to go
+		 * back to the old method of allocating the event
+		 * on the ring buffer, and if the filter fails, it
+		 * will have to call ring_buffer_discard_commit()
+		 * to remove it.
+		 *
+		 * Need to also check the unlikely case that the
+		 * length is bigger than the temp buffer size.
+		 * If that happens, then the reserve is pretty much
+		 * guaranteed to fail, as the ring buffer currently
+		 * only allows events less than a page. But that may
+		 * change in the future, so let the ring buffer reserve
+		 * handle the failure in that case.
+		 */
+		if (val == 1 && likely(len <= max_len)) {
 			trace_event_setup(entry, type, trace_ctx);
 			entry->array[0] = len;
 			return entry;
···
 
 int set_tracer_flag(struct trace_array *tr, unsigned int mask, int enabled)
 {
+	int *map;
+
 	if ((mask == TRACE_ITER_RECORD_TGID) ||
 	    (mask == TRACE_ITER_RECORD_CMD))
 		lockdep_assert_held(&event_mutex);
···
 		trace_event_enable_cmd_record(enabled);
 
 	if (mask == TRACE_ITER_RECORD_TGID) {
-		if (!tgid_map)
-			tgid_map = kvcalloc(PID_MAX_DEFAULT + 1,
-					   sizeof(*tgid_map),
-					   GFP_KERNEL);
+		if (!tgid_map) {
+			tgid_map_max = pid_max;
+			map = kvcalloc(tgid_map_max + 1, sizeof(*tgid_map),
+				       GFP_KERNEL);
+
+			/*
+			 * Pairs with smp_load_acquire() in
+			 * trace_find_tgid_ptr() to ensure that if it observes
+			 * the tgid_map we just allocated then it also observes
+			 * the corresponding tgid_map_max value.
+			 */
+			smp_store_release(&tgid_map, map);
+		}
 		if (!tgid_map) {
 			tr->trace_flags &= ~TRACE_ITER_RECORD_TGID;
 			return -ENOMEM;
···
 
 static void *saved_tgids_next(struct seq_file *m, void *v, loff_t *pos)
 {
-	int *ptr = v;
+	int pid = ++(*pos);
 
-	if (*pos || m->count)
-		ptr++;
-
-	(*pos)++;
-
-	for (; ptr <= &tgid_map[PID_MAX_DEFAULT]; ptr++) {
-		if (trace_find_tgid(*ptr))
-			return ptr;
-	}
-
-	return NULL;
+	return trace_find_tgid_ptr(pid);
 }
 
 static void *saved_tgids_start(struct seq_file *m, loff_t *pos)
 {
-	void *v;
-	loff_t l = 0;
+	int pid = *pos;
 
-	if (!tgid_map)
-		return NULL;
-
-	v = &tgid_map[0];
-	while (l <= *pos) {
-		v = saved_tgids_next(m, v, &l);
-		if (!v)
-			return NULL;
-	}
-
-	return v;
+	return trace_find_tgid_ptr(pid);
 }
 
 static void saved_tgids_stop(struct seq_file *m, void *v)
···
 
 static int saved_tgids_show(struct seq_file *m, void *v)
 {
-	int pid = (int *)v - tgid_map;
+	int *entry = (int *)v;
+	int pid = entry - tgid_map;
+	int tgid = *entry;
 
-	seq_printf(m, "%d %d\n", pid, trace_find_tgid(pid));
+	if (tgid == 0)
+		return SEQ_SKIP;
+
+	seq_printf(m, "%d %d\n", pid, tgid);
 	return 0;
 }
 
···
 ssize_t tracing_resize_ring_buffer(struct trace_array *tr,
 				  unsigned long size, int cpu_id)
 {
-	int ret = size;
+	int ret;
 
 	mutex_lock(&trace_types_lock);
 
···
 };
 
 #endif /* CONFIG_TRACER_SNAPSHOT */
+
+/*
+ * trace_min_max_write - Write a u64 value to a trace_min_max_param struct
+ * @filp: The active open file structure
+ * @ubuf: The userspace provided buffer to read value into
+ * @cnt: The maximum number of bytes to read
+ * @ppos: The current "file" position
+ *
+ * This function implements the write interface for a struct trace_min_max_param.
+ * The filp->private_data must point to a trace_min_max_param structure that
+ * defines where to write the value, the min and the max acceptable values,
+ * and a lock to protect the write.
+ */
+static ssize_t
+trace_min_max_write(struct file *filp, const char __user *ubuf, size_t cnt, loff_t *ppos)
+{
+	struct trace_min_max_param *param = filp->private_data;
+	u64 val;
+	int err;
+
+	if (!param)
+		return -EFAULT;
+
+	err = kstrtoull_from_user(ubuf, cnt, 10, &val);
+	if (err)
+		return err;
+
+	if (param->lock)
+		mutex_lock(param->lock);
+
+	if (param->min && val < *param->min)
+		err = -EINVAL;
+
+	if (param->max && val > *param->max)
+		err = -EINVAL;
+
+	if (!err)
+		*param->val = val;
+
+	if (param->lock)
+		mutex_unlock(param->lock);
+
+	if (err)
+		return err;
+
+	return cnt;
+}
+
+/*
+ * trace_min_max_read - Read a u64 value from a trace_min_max_param struct
+ * @filp: The active open file structure
+ * @ubuf: The userspace provided buffer to read value into
+ * @cnt: The maximum number of bytes to read
+ * @ppos: The current "file" position
+ *
+ * This function implements the read interface for a struct trace_min_max_param.
+ * The filp->private_data must point to a trace_min_max_param struct with valid
+ * data.
+ */
+static ssize_t
+trace_min_max_read(struct file *filp, char __user *ubuf, size_t cnt, loff_t *ppos)
+{
+	struct trace_min_max_param *param = filp->private_data;
+	char buf[U64_STR_SIZE];
+	int len;
+	u64 val;
+
+	if (!param)
+		return -EFAULT;
+
+	val = *param->val;
+
+	if (cnt > sizeof(buf))
+		cnt = sizeof(buf);
+
+	len = snprintf(buf, sizeof(buf), "%llu\n", val);
+
+	return simple_read_from_buffer(ubuf, cnt, ppos, buf, len);
+}
+
+const struct file_operations trace_min_max_fops = {
+	.open		= tracing_open_generic,
+	.read		= trace_min_max_read,
+	.write		= trace_min_max_write,
+};
 
 #define TRACING_LOG_ERRS_MAX	8
 #define TRACING_LOG_LOC_MAX	128
···
 	return 0;
 }
 
+fs_initcall(tracer_init_tracefs);
+
 static int trace_panic_handler(struct notifier_block *this,
 			       unsigned long event, void *unused)
 {
···
 	trace_event_init();
 }
 
-__init static int clear_boot_tracer(void)
+__init static void clear_boot_tracer(void)
 {
 	/*
 	 * The default tracer at boot buffer is an init section.
···
 	 * about to be freed.
 	 */
 	if (!default_bootup_tracer)
-		return 0;
+		return;
 
 	printk(KERN_INFO "ftrace bootup tracer '%s' not registered.\n",
 	       default_bootup_tracer);
 	default_bootup_tracer = NULL;
-
-	return 0;
 }
 
-fs_initcall(tracer_init_tracefs);
-late_initcall_sync(clear_boot_tracer);
-
 #ifdef CONFIG_HAVE_UNSTABLE_SCHED_CLOCK
-__init static int tracing_set_default_clock(void)
+__init static void tracing_set_default_clock(void)
 {
 	/* sched_clock_stable() is determined in late_initcall */
 	if (!trace_boot_clock && !sched_clock_stable()) {
 		if (security_locked_down(LOCKDOWN_TRACEFS)) {
 			pr_warn("Can not set tracing clock due to lockdown\n");
-			return -EPERM;
+			return;
 		}
 
 		printk(KERN_WARNING
···
 		       "on the kernel command line\n");
 		tracing_set_clock(&global_trace, "global");
 	}
+}
+#else
+static inline void tracing_set_default_clock(void) { }
+#endif
 
+__init static int late_trace_init(void)
+{
+	if (tracepoint_printk && tracepoint_printk_stop_on_boot) {
+		static_key_disable(&tracepoint_printk_key.key);
+		tracepoint_printk = 0;
+	}
+
+	tracing_set_default_clock();
+	clear_boot_tracer();
 	return 0;
 }
-late_initcall_sync(tracing_set_default_clock);
-#endif
+
+late_initcall_sync(late_trace_init);

kernel/trace/trace.h

···
 	TRACE_BLK,
 	TRACE_BPUTS,
 	TRACE_HWLAT,
+	TRACE_OSNOISE,
+	TRACE_TIMERLAT,
 	TRACE_RAW_DATA,
 	TRACE_FUNC_REPEATS,
 
···
 	struct array_buffer	max_buffer;
 	bool			allocated_snapshot;
 #endif
-#if defined(CONFIG_TRACER_MAX_TRACE) || defined(CONFIG_HWLAT_TRACER)
+#if defined(CONFIG_TRACER_MAX_TRACE) || defined(CONFIG_HWLAT_TRACER) \
+	|| defined(CONFIG_OSNOISE_TRACER)
 	unsigned long		max_latency;
 #ifdef CONFIG_FSNOTIFY
 	struct dentry		*d_max_latency;
···
 		IF_ASSIGN(var, ent, struct bprint_entry, TRACE_BPRINT);	\
 		IF_ASSIGN(var, ent, struct bputs_entry, TRACE_BPUTS);	\
 		IF_ASSIGN(var, ent, struct hwlat_entry, TRACE_HWLAT);	\
+		IF_ASSIGN(var, ent, struct osnoise_entry, TRACE_OSNOISE);\
+		IF_ASSIGN(var, ent, struct timerlat_entry, TRACE_TIMERLAT);\
 		IF_ASSIGN(var, ent, struct raw_data_entry, TRACE_RAW_DATA);\
 		IF_ASSIGN(var, ent, struct trace_mmiotrace_rw,		\
 			  TRACE_MMIO_RW);				\
···
 			  struct task_struct *tsk, int cpu);
 #endif /* CONFIG_TRACER_MAX_TRACE */
 
-#if (defined(CONFIG_TRACER_MAX_TRACE) || defined(CONFIG_HWLAT_TRACER)) && \
-	defined(CONFIG_FSNOTIFY)
+#if (defined(CONFIG_TRACER_MAX_TRACE) || defined(CONFIG_HWLAT_TRACER) \
+	|| defined(CONFIG_OSNOISE_TRACER)) && defined(CONFIG_FSNOTIFY)
+#define LATENCY_FS_NOTIFY
+#endif
 
+#ifdef LATENCY_FS_NOTIFY
 void latency_fsnotify(struct trace_array *tr);
-
 #else
-
 static inline void latency_fsnotify(struct trace_array *tr) { }
-
 #endif
 
 #ifdef CONFIG_STACKTRACE
···
 	}
 	return true;
 }
+
+/*
+ * This is a generic way to read and write a u64 value from a file in tracefs.
+ *
+ * The value is stored on the variable pointed by *val. The value needs
+ * to be at least *min and at most *max. The write is protected by an
+ * existing *lock.
+ */
+struct trace_min_max_param {
+	struct mutex	*lock;
+	u64		*val;
+	u64		*min;
+	u64		*max;
+};
+
+#define U64_STR_SIZE		24	/* 20 digits max */
+
+extern const struct file_operations trace_min_max_fops;
 
 #endif /* _LINUX_KERNEL_TRACE_H */

kernel/trace/trace_boot.c

···
 trace_boot_init_events(struct trace_array *tr, struct xbc_node *node)
 {
 	struct xbc_node *gnode, *enode;
+	bool enable, enable_all = false;
+	const char *data;
 
 	node = xbc_node_find_child(node, "event");
 	if (!node)
 		return;
 	/* per-event key starts with "event.GROUP.EVENT" */
-	xbc_node_for_each_child(node, gnode)
-		xbc_node_for_each_child(gnode, enode)
+	xbc_node_for_each_child(node, gnode) {
+		data = xbc_node_get_data(gnode);
+		if (!strcmp(data, "enable")) {
+			enable_all = true;
+			continue;
+		}
+		enable = false;
+		xbc_node_for_each_child(gnode, enode) {
+			data = xbc_node_get_data(enode);
+			if (!strcmp(data, "enable")) {
+				enable = true;
+				continue;
+			}
 			trace_boot_init_one_event(tr, gnode, enode);
+		}
+		/* Event enablement must be done after event settings */
+		if (enable) {
+			data = xbc_node_get_data(gnode);
+			trace_array_set_clr_event(tr, data, NULL, true);
+		}
+	}
+	/* Ditto */
+	if (enable_all)
+		trace_array_set_clr_event(tr, NULL, NULL, true);
 }
 #else
 #define trace_boot_enable_events(tr, node) do {} while (0)

kernel/trace/trace_entries.h

···
 		 __entry->count,
 		 FUNC_REPEATS_GET_DELTA_TS(__entry))
 );
+
+FTRACE_ENTRY(osnoise, osnoise_entry,
+
+	TRACE_OSNOISE,
+
+	F_STRUCT(
+		__field(	u64,			noise		)
+		__field(	u64,			runtime		)
+		__field(	u64,			max_sample	)
+		__field(	unsigned int,		hw_count	)
+		__field(	unsigned int,		nmi_count	)
+		__field(	unsigned int,		irq_count	)
+		__field(	unsigned int,		softirq_count	)
+		__field(	unsigned int,		thread_count	)
+	),
+
+	F_printk("noise:%llu\tmax_sample:%llu\thw:%u\tnmi:%u\tirq:%u\tsoftirq:%u\tthread:%u\n",
+		 __entry->noise,
+		 __entry->max_sample,
+		 __entry->hw_count,
+		 __entry->nmi_count,
+		 __entry->irq_count,
+		 __entry->softirq_count,
+		 __entry->thread_count)
+);
+
+FTRACE_ENTRY(timerlat, timerlat_entry,
+
+	TRACE_TIMERLAT,
+
+	F_STRUCT(
+		__field(	unsigned int,		seqnum		)
+		__field(	int,			context		)
+		__field(	u64,			timer_latency	)
+	),
+
+	F_printk("seq:%u\tcontext:%d\ttimer_latency:%llu\n",
+		 __entry->seqnum,
+		 __entry->context,
+		 __entry->timer_latency)
+);

kernel/trace/trace_events_hist.c

···
 		      char *subsys_name, char *event_name, char *field_name)
 {
 	struct trace_array *tr = target_hist_data->event_file->tr;
-	struct hist_field *event_var = ERR_PTR(-EINVAL);
 	struct hist_trigger_data *hist_data;
 	unsigned int i, n, first = true;
 	struct field_var_hist *var_hist;
 	struct trace_event_file *file;
 	struct hist_field *key_field;
+	struct hist_field *event_var;
 	char *saved_filter;
 	char *cmd;
 	int ret;
···
 		cmd = hist_data->field_var_hists[i]->cmd;
 		ret = event_hist_trigger_func(&trigger_hist_cmd, file,
 					      "!hist", "hist", cmd);
+		WARN_ON_ONCE(ret < 0);
 	}
 }
 

kernel/trace/trace_events_trigger.c

···
 
 /**
  * set_named_trigger_data - Associate common named trigger data
- * @data: The trigger data of a named trigger to unpause
+ * @data: The trigger data to associate
+ * @named_data: The common named trigger to be associated
  *
  * Named triggers are sets of triggers that share a common set of
  * trigger data.  The first named trigger registered with a given name

kernel/trace/trace_hwlat.c

···
  * Copyright (C) 2008-2009 Jon Masters, Red Hat, Inc. <[e-mail]>
  * Copyright (C) 2013-2016 Steven Rostedt, Red Hat, Inc. <[e-mail]>
  *
- * Includes useful feedback from Clark Williams <[e-mail]>
+ * Includes useful feedback from Clark Williams <[e-mail]>
  *
  */
 #include <linux/kthread.h>
···
 #define DEFAULT_SAMPLE_WIDTH	500000			/* 0.5s */
 #define DEFAULT_LAT_THRESHOLD	10			/* 10us */
 
-/* sampling thread*/
-static struct task_struct *hwlat_kthread;
-
 static struct dentry *hwlat_sample_width;	/* sample width us */
 static struct dentry *hwlat_sample_window;	/* sample window us */
+static struct dentry *hwlat_thread_mode;	/* hwlat thread mode */
+
+enum {
+	MODE_NONE = 0,
+	MODE_ROUND_ROBIN,
+	MODE_PER_CPU,
+	MODE_MAX
+};
+static char *thread_mode_str[] = { "none", "round-robin", "per-cpu" };
 
 /* Save the previous tracing_thresh value */
 static unsigned long save_tracing_thresh;
 
-/* NMI timestamp counters */
-static u64 nmi_ts_start;
-static u64 nmi_total_ts;
-static int nmi_count;
-static int nmi_cpu;
+/* runtime kthread data */
+struct hwlat_kthread_data {
+	struct task_struct	*kthread;
+	/* NMI timestamp counters */
+	u64			nmi_ts_start;
+	u64			nmi_total_ts;
+	int			nmi_count;
+	int			nmi_cpu;
+};
+
+struct hwlat_kthread_data hwlat_single_cpu_data;
+DEFINE_PER_CPU(struct hwlat_kthread_data, hwlat_per_cpu_data);
 
 /* Tells NMIs to call back to the hwlat tracer to record timestamps */
 bool trace_hwlat_callback_enabled;
···
 	u64	sample_window;		/* total sampling window (on+off) */
 	u64	sample_width;		/* active sampling portion of window */
 
+	int	thread_mode;		/* thread mode */
+
 } hwlat_data = {
 	.sample_window		= DEFAULT_SAMPLE_WINDOW,
 	.sample_width		= DEFAULT_SAMPLE_WIDTH,
+	.thread_mode		= MODE_ROUND_ROBIN
 };
+
+static struct hwlat_kthread_data *get_cpu_data(void)
+{
+	if (hwlat_data.thread_mode == MODE_PER_CPU)
+		return this_cpu_ptr(&hwlat_per_cpu_data);
+	else
+		return &hwlat_single_cpu_data;
+}
+
+static bool hwlat_busy;
 
 static void trace_hwlat_sample(struct hwlat_sample *sample)
 {
···
 
 void trace_hwlat_callback(bool enter)
 {
-	if (smp_processor_id() != nmi_cpu)
+	struct hwlat_kthread_data *kdata = get_cpu_data();
+
+	if (!kdata->kthread)
 		return;
 
 	/*
···
 	 */
 	if (!IS_ENABLED(CONFIG_GENERIC_SCHED_CLOCK)) {
 		if (enter)
-			nmi_ts_start = time_get();
+			kdata->nmi_ts_start = time_get();
 		else
-			nmi_total_ts += time_get() - nmi_ts_start;
+			kdata->nmi_total_ts += time_get() - kdata->nmi_ts_start;
 	}
 
 	if (enter)
-		nmi_count++;
+		kdata->nmi_count++;
 }
+
+/*
+ * hwlat_err - report a hwlat error.
+ */
+#define hwlat_err(msg) ({							\
+	struct trace_array *tr = hwlat_trace;					\
+										\
+	trace_array_printk_buf(tr->array_buffer.buffer, _THIS_IP_, msg);	\
+})
 
 /**
  * get_sample - sample the CPU TSC and look for likely hardware latencies
···
  */
 static int get_sample(void)
 {
+	struct hwlat_kthread_data *kdata = get_cpu_data();
 	struct trace_array *tr = hwlat_trace;
 	struct hwlat_sample s;
 	time_type start, t1, t2, last_t2;
···
 
 	do_div(thresh, NSEC_PER_USEC); /* modifies interval value */
 
-	nmi_cpu = smp_processor_id();
-	nmi_total_ts = 0;
-	nmi_count = 0;
+	kdata->nmi_total_ts = 0;
+	kdata->nmi_count = 0;
 	/* Make sure NMIs see this first */
 	barrier();
 
···
 			outer_diff = time_to_us(time_sub(t1, last_t2));
 			/* This shouldn't happen */
 			if (outer_diff < 0) {
-				pr_err(BANNER "time running backwards\n");
+				hwlat_err(BANNER "time running backwards\n");
 				goto out;
 			}
 			if (outer_diff > outer_sample)
···
 
 		/* Check for possible overflows */
 		if (total < last_total) {
-			pr_err("Time total overflowed\n");
+			hwlat_err("Time total overflowed\n");
 			break;
 		}
 		last_total = total;
···
 
 		/* This shouldn't happen */
 		if (diff < 0) {
-			pr_err(BANNER "time running backwards\n");
+			hwlat_err(BANNER "time running backwards\n");
 			goto out;
 		}
 
···
 		ret = 1;
 
 		/* We read in microseconds */
-		if (nmi_total_ts)
-			do_div(nmi_total_ts, NSEC_PER_USEC);
+		if (kdata->nmi_total_ts)
+			do_div(kdata->nmi_total_ts, NSEC_PER_USEC);
 
 		hwlat_data.count++;
 		s.seqnum = hwlat_data.count;
 		s.duration = sample;
 		s.outer_duration = outer_sample;
-		s.nmi_total_ts = nmi_total_ts;
-		s.nmi_count = nmi_count;
+		s.nmi_total_ts = kdata->nmi_total_ts;
+		s.nmi_count = kdata->nmi_count;
 		s.count = count;
 		trace_hwlat_sample(&s);
 
···
 }
 
 static struct cpumask save_cpumask;
-static bool disable_migrate;
 
 static void move_to_next_cpu(void)
 {
···
 	struct trace_array *tr = hwlat_trace;
 	int next_cpu;
 
-	if (disable_migrate)
-		return;
 	/*
 	 * If for some reason the user modifies the CPU affinity
 	 * of this thread, then stop migrating for the duration
 	 * of the current test.
 	 */
 	if (!cpumask_equal(current_mask, current->cpus_ptr))
-		goto disable;
+		goto change_mode;
 
 	get_online_cpus();
 	cpumask_and(current_mask, cpu_online_mask, tr->tracing_cpumask);
···
 		next_cpu = cpumask_first(current_mask);
 
 	if (next_cpu >= nr_cpu_ids) /* Shouldn't happen! */
-		goto disable;
+		goto change_mode;
 
 	cpumask_clear(current_mask);
 	cpumask_set_cpu(next_cpu, current_mask);
···
 	sched_setaffinity(0, current_mask);
 	return;
 
- disable:
-	disable_migrate = true;
+ change_mode:
+	hwlat_data.thread_mode = MODE_NONE;
+	pr_info(BANNER "cpumask changed while in round-robin mode, switching to mode none\n");
 }
 
 /*
···
 
 	while (!kthread_should_stop()) {
 
-		move_to_next_cpu();
+		if (hwlat_data.thread_mode == MODE_ROUND_ROBIN)
+			move_to_next_cpu();
 
 		local_irq_disable();
 		get_sample();
···
 	return 0;
 }
 
-/**
- * start_kthread - Kick off the hardware latency sampling/detector kthread
+/*
+ * stop_stop_kthread - Inform the hardware latency sampling/detector kthread to stop
+ *
+ * This kicks the running hardware latency sampling/detector kernel thread and
+ * tells it to stop sampling now. Use this on unload and at system shutdown.
+ */
+static void stop_single_kthread(void)
+{
+	struct hwlat_kthread_data *kdata = get_cpu_data();
+	struct task_struct *kthread;
+
+	get_online_cpus();
+	kthread = kdata->kthread;
+
+	if (!kthread)
+		goto out_put_cpus;
+
+	kthread_stop(kthread);
+	kdata->kthread = NULL;
+
+out_put_cpus:
+	put_online_cpus();
+}
+
+
+/*
+ * start_single_kthread - Kick off the hardware latency sampling/detector kthread
  *
  * This starts the kernel thread that will sit and sample the CPU timestamp
  * counter (TSC or similar) and look for potential hardware latencies.
  */
-static int start_kthread(struct trace_array *tr)
+static int start_single_kthread(struct trace_array *tr)
 {
+	struct hwlat_kthread_data *kdata = get_cpu_data();
 	struct cpumask *current_mask = &save_cpumask;
 	struct task_struct *kthread;
 	int next_cpu;
 
-	if (hwlat_kthread)
-		return 0;
-
-	/* Just pick the first CPU on first iteration */
 	get_online_cpus();
-	cpumask_and(current_mask, cpu_online_mask, tr->tracing_cpumask);
-	put_online_cpus();
-	next_cpu = cpumask_first(current_mask);
+	if (kdata->kthread)
+		goto out_put_cpus;
 
 	kthread = kthread_create(kthread_fn, NULL, "hwlatd");
+	if (IS_ERR(kthread)) {
+		pr_err(BANNER "could not start sampling thread\n");
+		put_online_cpus();
+		return -ENOMEM;
+	}
+
+	/* Just pick the first CPU on first iteration */
+	cpumask_and(current_mask, cpu_online_mask, tr->tracing_cpumask);
+
+	if (hwlat_data.thread_mode == MODE_ROUND_ROBIN) {
+		next_cpu = cpumask_first(current_mask);
+		cpumask_clear(current_mask);
+		cpumask_set_cpu(next_cpu, current_mask);
+
+	}
+
+	sched_setaffinity(kthread->pid, current_mask);
+
+	kdata->kthread = kthread;
+	wake_up_process(kthread);
+
+out_put_cpus:
+	put_online_cpus();
+	return 0;
+}
+
+/*
+ * stop_cpu_kthread - Stop a hwlat cpu kthread
+ */
+static void stop_cpu_kthread(unsigned int cpu)
+{
+	struct task_struct *kthread;
+
+	kthread = per_cpu(hwlat_per_cpu_data, cpu).kthread;
+	if (kthread)
+		kthread_stop(kthread);
+	per_cpu(hwlat_per_cpu_data, cpu).kthread = NULL;
+}
+
+/*
+ * stop_per_cpu_kthreads - Inform the hardware latency sampling/detector kthread to stop
+ *
+ * This kicks the running hardware latency sampling/detector kernel threads and
+ * tells it to stop sampling now. Use this on unload and at system shutdown.
+ */
+static void stop_per_cpu_kthreads(void)
+{
+	unsigned int cpu;
+
+	get_online_cpus();
+	for_each_online_cpu(cpu)
+		stop_cpu_kthread(cpu);
+	put_online_cpus();
+}
+
+/*
+ * start_cpu_kthread - Start a hwlat cpu kthread
+ */
+static int start_cpu_kthread(unsigned int cpu)
+{
+	struct task_struct *kthread;
+	char comm[24];
+
+	snprintf(comm, 24, "hwlatd/%d", cpu);
+
+	kthread = kthread_create_on_cpu(kthread_fn, NULL, cpu, comm);
 	if (IS_ERR(kthread)) {
 		pr_err(BANNER "could not start sampling thread\n");
 		return -ENOMEM;
 	}
 
-	cpumask_clear(current_mask);
-	cpumask_set_cpu(next_cpu, current_mask);
-	sched_setaffinity(kthread->pid, current_mask);
-
-	hwlat_kthread = kthread;
+	per_cpu(hwlat_per_cpu_data, cpu).kthread = kthread;
 	wake_up_process(kthread);
 
 	return 0;
 }
 
-/**
- * stop_kthread - Inform the hardware latency sampling/detector kthread to stop
- *
- * This kicks the running hardware latency sampling/detector kernel thread and
- * tells it to stop sampling now. Use this on unload and at system shutdown.
- */
-static void stop_kthread(void)
+#ifdef CONFIG_HOTPLUG_CPU
+static void hwlat_hotplug_workfn(struct work_struct *dummy)
 {
-	if (!hwlat_kthread)
-		return;
-	kthread_stop(hwlat_kthread);
-	hwlat_kthread = NULL;
+	struct trace_array *tr = hwlat_trace;
+	unsigned int cpu = smp_processor_id();
+
+	mutex_lock(&trace_types_lock);
+	mutex_lock(&hwlat_data.lock);
+	get_online_cpus();
+
+	if (!hwlat_busy || hwlat_data.thread_mode != MODE_PER_CPU)
+		goto out_unlock;
+
+	if (!cpumask_test_cpu(cpu, tr->tracing_cpumask))
+		goto out_unlock;
+
+	start_cpu_kthread(cpu);
+
+out_unlock:
+	put_online_cpus();
+	mutex_unlock(&hwlat_data.lock);
+	mutex_unlock(&trace_types_lock);
+}
+
+static DECLARE_WORK(hwlat_hotplug_work, hwlat_hotplug_workfn);
+
+/*
+ * hwlat_cpu_init - CPU hotplug online callback function
+ */
+static int hwlat_cpu_init(unsigned int cpu)
+{
+	schedule_work_on(cpu, &hwlat_hotplug_work);
+	return 0;
 }
 
 /*
- * hwlat_read - Wrapper read function for reading both window and width
- * @filp: The active open file structure
- * @ubuf: The userspace provided buffer to read value into
- * @cnt: The maximum number of bytes to read
- * @ppos: The current "file" position
- *
- * This function provides a generic read implementation for the global state
- * "hwlat_data" structure filesystem entries.
+ * hwlat_cpu_die - CPU hotplug offline callback function
  */
-static ssize_t hwlat_read(struct file *filp, char __user *ubuf,
-			  size_t cnt, loff_t *ppos)
+static int hwlat_cpu_die(unsigned int cpu)
 {
-	char buf[U64STR_SIZE];
-	u64 *entry = filp->private_data;
-	u64 val;
-	int len;
+	stop_cpu_kthread(cpu);
+	return 0;
+}
 
-	if (!entry)
+static void hwlat_init_hotplug_support(void)
+{
+	int ret;
+
+	ret = cpuhp_setup_state(CPUHP_AP_ONLINE_DYN, "trace/hwlat:online",
+				hwlat_cpu_init, hwlat_cpu_die);
+	if (ret < 0)
+		pr_warn(BANNER "Error to init cpu hotplug support\n");
+
+	return;
+}
+#else /* CONFIG_HOTPLUG_CPU */
+static void hwlat_init_hotplug_support(void)
+{
+	return;
+}
+#endif /* CONFIG_HOTPLUG_CPU */
+
+/*
+ * start_per_cpu_kthreads - Kick off the hardware latency sampling/detector kthreads
+ *
+ * This starts the kernel threads that will sit on potentially all cpus and
+ * sample the CPU timestamp counter (TSC or similar) and look for potential
+ * hardware latencies.
+ */
+static int start_per_cpu_kthreads(struct trace_array *tr)
+{
+	struct cpumask *current_mask = &save_cpumask;
+	unsigned int cpu;
+	int retval;
+
+	get_online_cpus();
+	/*
+	 * Run only on CPUs in which hwlat is allowed to run.
+	 */
+	cpumask_and(current_mask, cpu_online_mask, tr->tracing_cpumask);
+
+	for_each_online_cpu(cpu)
+		per_cpu(hwlat_per_cpu_data, cpu).kthread = NULL;
+
+	for_each_cpu(cpu, current_mask) {
+		retval = start_cpu_kthread(cpu);
+		if (retval)
+			goto out_error;
+	}
+	put_online_cpus();
+
+	return 0;
+
+out_error:
+	put_online_cpus();
+	stop_per_cpu_kthreads();
+	return retval;
+}
+
+static void *s_mode_start(struct seq_file *s, loff_t *pos)
+{
+	int mode = *pos;
+
+	mutex_lock(&hwlat_data.lock);
+
+	if (mode >= MODE_MAX)
+		return NULL;
+
+	return pos;
+}
+
+static void *s_mode_next(struct seq_file *s, void *v, loff_t *pos)
+{
+	int mode = ++(*pos);
+
+	if (mode >= MODE_MAX)
+		return NULL;
+
+	return pos;
+}
+
+static int s_mode_show(struct seq_file *s, void *v)
+{
+	loff_t *pos = v;
+	int mode = *pos;
+
+	if (mode == hwlat_data.thread_mode)
+		seq_printf(s, "[%s]", thread_mode_str[mode]);
+	else
+		seq_printf(s, "%s", thread_mode_str[mode]);
+
+	if (mode != MODE_MAX)
+		seq_puts(s, " ");
+
+	return 0;
+}
+
+static void s_mode_stop(struct seq_file *s, void *v)
+{
+	seq_puts(s, "\n");
+	mutex_unlock(&hwlat_data.lock);
+}
+
+static const struct seq_operations thread_mode_seq_ops = {
+	.start		= s_mode_start,
+	.next		= s_mode_next,
+	.show		= s_mode_show,
+	.stop		= s_mode_stop
+};
+
+static int hwlat_mode_open(struct inode *inode, struct file *file)
+{
+	return seq_open(file, &thread_mode_seq_ops);
+};
+
+static void hwlat_tracer_start(struct trace_array *tr);
+static void hwlat_tracer_stop(struct trace_array *tr);
+
+/**
+ * hwlat_mode_write - Write function for "mode" entry
+ * @filp: The active open file structure
+ * @ubuf: The user buffer that contains the value to write
+ * @cnt: The maximum number of bytes to write to "file"
+ * @ppos: The current position in @file
+ *
+ * This function provides a write implementation for the "mode" interface
+ * to the hardware latency detector. hwlatd has different operation modes.
+ * The "none" sets the allowed cpumask for a single hwlatd thread at the
+ * startup and lets the scheduler handle the migration. The default mode is
+ * the "round-robin" one, in which a single hwlatd thread runs, migrating
+ * among the allowed CPUs in a round-robin fashion. The "per-cpu" mode
+ * creates one hwlatd thread per allowed CPU.
+ */
+static ssize_t hwlat_mode_write(struct file *filp, const char __user *ubuf,
+				 size_t cnt, loff_t *ppos)
+{
+	struct trace_array *tr = hwlat_trace;
+	const char *mode;
+	char buf[64];
+	int ret, i;
+
+	if (cnt >= sizeof(buf))
+		return -EINVAL;
+
+	if (copy_from_user(buf, ubuf, cnt))
 		return -EFAULT;
 
-	if (cnt > sizeof(buf))
-		cnt = sizeof(buf);
+	buf[cnt] = 0;
 
-	val = *entry;
+	mode = strstrip(buf);
 
-	len = snprintf(buf, sizeof(buf), "%llu\n", val);
+	ret = -EINVAL;
 
-	return simple_read_from_buffer(ubuf, cnt, ppos, buf, len);
-}
-
-/**
- * hwlat_width_write - Write function for "width" entry
- * @filp: The active open file structure
- * @ubuf: The user buffer that contains the value to write
- * @cnt: The maximum number of bytes to write to "file"
- * @ppos: The current position in @file
- *
- * This function provides a write implementation for the "width" interface
- * to the hardware latency detector. It can be used to configure
- * for how many us of the total window us we will actively sample for any
- * hardware-induced latency periods. Obviously, it is not possible to
- * sample constantly and have the system respond to a sample reader, or,
- * worse, without having the system appear to have gone out to lunch. It
- * is enforced that width is less that the total window size.
- */
-static ssize_t
-hwlat_width_write(struct file *filp, const char __user *ubuf,
-		  size_t cnt, loff_t *ppos)
-{
-	u64 val;
-	int err;
-
-	err = kstrtoull_from_user(ubuf, cnt, 10, &val);
-	if (err)
-		return err;
+	/*
+	 * trace_types_lock is taken to avoid concurrency on start/stop
+	 * and hwlat_busy.
+	 */
+	mutex_lock(&trace_types_lock);
+	if (hwlat_busy)
+		hwlat_tracer_stop(tr);
 
 	mutex_lock(&hwlat_data.lock);
-	if (val < hwlat_data.sample_window)
-		hwlat_data.sample_width = val;
-	else
-		err = -EINVAL;
+
+	for (i = 0; i < MODE_MAX; i++) {
+		if (strcmp(mode, thread_mode_str[i]) == 0) {
+			hwlat_data.thread_mode = i;
+			ret = cnt;
+		}
+	}
+
 	mutex_unlock(&hwlat_data.lock);
 
-	if (err)
-		return err;
+	if (hwlat_busy)
+		hwlat_tracer_start(tr);
+	mutex_unlock(&trace_types_lock);
 
-	return cnt;
+	*ppos += cnt;
+
+
+
+	return ret;
 }
 
-/**
- * hwlat_window_write - Write function for "window" entry
- * @filp: The active open file structure
- * @ubuf: The user buffer that contains the value to write
- * @cnt: The maximum number of bytes to write to "file"
- * @ppos: The current position in @file
- *
- * This function provides a write implementation for the "window" interface
- * to the hardware latency detector. The window is the total time
- * in us that will be considered one sample period. Conceptually, windows
- * occur back-to-back and contain a sample width period during which
- * actual sampling occurs. Can be used to write a new total window size. It
- * is enforced that any value written must be greater than the sample width
- * size, or an error results.
+/*
+ * The width parameter is read/write using the generic trace_min_max_param
+ * method. The *val is protected by the hwlat_data lock and is upper
+ * bounded by the window parameter.
  */
-static ssize_t
-hwlat_window_write(struct file *filp, const char __user *ubuf,
-		   size_t cnt, loff_t *ppos)
-{
-	u64 val;
-	int err;
-
-	err = kstrtoull_from_user(ubuf, cnt, 10, &val);
-	if (err)
-		return err;
-
-	mutex_lock(&hwlat_data.lock);
-	if (hwlat_data.sample_width < val)
-		hwlat_data.sample_window = val;
-	else
-		err = -EINVAL;
-	mutex_unlock(&hwlat_data.lock);
-
-	if (err)
-		return err;
-
-	return cnt;
-}
-
-static const struct file_operations width_fops = {
-	.open		= tracing_open_generic,
-	.read		= hwlat_read,
-	.write		= hwlat_width_write,
+static struct trace_min_max_param hwlat_width = {
+	.lock		= &hwlat_data.lock,
+	.val		= &hwlat_data.sample_width,
+	.max		= &hwlat_data.sample_window,
+	.min		= NULL,
 };
 
-static const struct file_operations window_fops = {
-	.open		= tracing_open_generic,
-	.read		= hwlat_read,
-	.write		= hwlat_window_write,
+/*
+ * The window parameter is read/write using the generic trace_min_max_param
+ * method. The *val is protected by the hwlat_data lock and is lower
+ * bounded by the width parameter.
+ */
+static struct trace_min_max_param hwlat_window = {
+	.lock		= &hwlat_data.lock,
+	.val		= &hwlat_data.sample_window,
+	.max		= NULL,
+	.min		= &hwlat_data.sample_width,
 };
 
+static const struct file_operations thread_mode_fops = {
+	.open		= hwlat_mode_open,
+	.read		= seq_read,
+	.llseek		= seq_lseek,
+	.release	= seq_release,
+	.write		= hwlat_mode_write
+};
 /**
  * init_tracefs - A function to initialize the tracefs interface files
  *
···
 
 	hwlat_sample_window = tracefs_create_file("window", 0640,
 						  top_dir,
-						  &hwlat_data.sample_window,
-						  &window_fops);
+						  &hwlat_window,
+						  &trace_min_max_fops);
 	if (!hwlat_sample_window)
 		goto err;
 
 	hwlat_sample_width = tracefs_create_file("width", 0644,
 						 top_dir,
-						 &hwlat_data.sample_width,
-						 &width_fops);
+						 &hwlat_width,
+						 &trace_min_max_fops);
 	if (!hwlat_sample_width)
+		goto err;
+
+	hwlat_thread_mode = trace_create_file("mode", 0644,
+					      top_dir,
+					      NULL,
+					      &thread_mode_fops);
+	if (!hwlat_thread_mode)
 		goto err;
 
 	return 0;
···
 {
 	int err;
 
-	err = start_kthread(tr);
+	if (hwlat_data.thread_mode == MODE_PER_CPU)
+		err = start_per_cpu_kthreads(tr);
+	else
+		err = start_single_kthread(tr);
 	if (err)
 		pr_err(BANNER "Cannot start hwlat kthread\n");
 }
 
 static void hwlat_tracer_stop(struct trace_array *tr)
 {
-	stop_kthread();
+	if (hwlat_data.thread_mode == MODE_PER_CPU)
+		stop_per_cpu_kthreads();
+	else
+		stop_single_kthread();
 }
-
-static bool hwlat_busy;
 
 static int hwlat_tracer_init(struct trace_array *tr)
 {
···
 
 	hwlat_trace = tr;
 
-	disable_migrate = false;
 	hwlat_data.count = 0;
 	tr->max_latency = 0;
 	save_tracing_thresh = tracing_thresh;
···
 
 static void hwlat_tracer_reset(struct trace_array *tr)
 {
-	stop_kthread();
+	hwlat_tracer_stop(tr);
 
 	/* the tracing threshold is static between runs */
 	last_tracing_thresh = tracing_thresh;
···
 	ret = register_tracer(&hwlat_tracer);
 	if (ret)
 		return ret;
+
+	hwlat_init_hotplug_support();
 
 	init_tracefs();
 

kernel/trace/trace_osnoise.c

···
+// SPDX-License-Identifier: GPL-2.0
+/*
+ * OS Noise Tracer: computes the OS Noise suffered by a running thread.
+ * Timerlat Tracer: measures the wakeup latency of a timer triggered IRQ and thread.
+ *
+ * Based on "hwlat_detector" tracer by:
+ *   Copyright (C) 2008-2009 Jon Masters, Red Hat, Inc. <[e-mail]>
+ *   Copyright (C) 2013-2016 Steven Rostedt, Red Hat, Inc. <[e-mail]>
+ *   With feedback from Clark Williams <[e-mail]>
+ *
+ * And also based on the rtsl tracer presented on:
+ *  DE OLIVEIRA, Daniel Bristot, et al. Demystifying the real-time linux
+ *  scheduling latency. In: 32nd Euromicro Conference on Real-Time Systems
+ *  (ECRTS 2020). Schloss Dagstuhl-Leibniz-Zentrum fur Informatik, 2020.
+ *
+ * Copyright (C) 2021 Daniel Bristot de Oliveira, Red Hat, Inc. <[e-mail]>
+ */
+
+#include <linux/kthread.h>
+#include <linux/tracefs.h>
+#include <linux/uaccess.h>
+#include <linux/cpumask.h>
+#include <linux/delay.h>
+#include <linux/sched/clock.h>
+#include <uapi/linux/sched/types.h>
+#include <linux/sched.h>
+#include "trace.h"
+
+#ifdef CONFIG_X86_LOCAL_APIC
+#include <asm/trace/irq_vectors.h>
+#undef TRACE_INCLUDE_PATH
+#undef TRACE_INCLUDE_FILE
+#endif /* CONFIG_X86_LOCAL_APIC */
+
+#include <trace/events/irq.h>
+#include <trace/events/sched.h>
+
+#define CREATE_TRACE_POINTS
+#include <trace/events/osnoise.h>
+
+static struct trace_array	*osnoise_trace;
+
+/*
+ * Default values.
+ */
+#define BANNER			"osnoise: "
+#define DEFAULT_SAMPLE_PERIOD	1000000			/* 1s */
+#define DEFAULT_SAMPLE_RUNTIME	1000000			/* 1s */
+
+#define DEFAULT_TIMERLAT_PERIOD	1000			/* 1ms */
+#define DEFAULT_TIMERLAT_PRIO	95			/* FIFO 95 */
+
+/*
+ * NMI runtime info.
+ */
+struct osn_nmi {
+	u64	count;
+	u64	delta_start;
+};
+
+/*
+ * IRQ runtime info.
+ */
+struct osn_irq {
+	u64	count;
+	u64	arrival_time;
+	u64	delta_start;
+};
+
+#define IRQ_CONTEXT	0
+#define THREAD_CONTEXT	1
+/*
+ * sofirq runtime info.
+ */
+struct osn_softirq {
+	u64	count;
+	u64	arrival_time;
+	u64	delta_start;
+};
+
+/*
+ * thread runtime info.
+ */
+struct osn_thread {
+	u64	count;
+	u64	arrival_time;
+	u64	delta_start;
+};
+
+/*
+ * Runtime information: this structure saves the runtime information used by
+ * one sampling thread.
+ */
+struct osnoise_variables {
+	struct task_struct	*kthread;
+	bool			sampling;
+	pid_t			pid;
+	struct osn_nmi		nmi;
+	struct osn_irq		irq;
+	struct osn_softirq	softirq;
+	struct osn_thread	thread;
+	local_t			int_counter;
+};
+
+/*
+ * Per-cpu runtime information.
+ */
+DEFINE_PER_CPU(struct osnoise_variables, per_cpu_osnoise_var);
+
+/*
+ * this_cpu_osn_var - Return the per-cpu osnoise_variables on its relative CPU
+ */
+static inline struct osnoise_variables *this_cpu_osn_var(void)
+{
+	return this_cpu_ptr(&per_cpu_osnoise_var);
+}
+
+#ifdef CONFIG_TIMERLAT_TRACER
+/*
+ * Runtime information for the timer mode.
+ */
+struct timerlat_variables {
+	struct task_struct	*kthread;
+	struct hrtimer		timer;
+	u64			rel_period;
+	u64			abs_period;
+	bool			tracing_thread;
+	u64			count;
+};
+
+DEFINE_PER_CPU(struct timerlat_variables, per_cpu_timerlat_var);
+
+/*
+ * this_cpu_tmr_var - Return the per-cpu timerlat_variables on its relative CPU
+ */
+static inline struct timerlat_variables *this_cpu_tmr_var(void)
+{
+	return this_cpu_ptr(&per_cpu_timerlat_var);
+}
+
+/*
+ * tlat_var_reset - Reset the values of the given timerlat_variables
+ */
+static inline void tlat_var_reset(void)
+{
+	struct timerlat_variables *tlat_var;
+	int cpu;
+	/*
+	 * So far, all the values are initialized as 0, so
+	 * zeroing the structure is perfect.
+	 */
+	for_each_cpu(cpu, cpu_online_mask) {
+		tlat_var = per_cpu_ptr(&per_cpu_timerlat_var, cpu);
+		memset(tlat_var, 0, sizeof(*tlat_var));
+	}
+}
+#else /* CONFIG_TIMERLAT_TRACER */
+#define tlat_var_reset()	do {} while (0)
+#endif /* CONFIG_TIMERLAT_TRACER */
+
+/*
+ * osn_var_reset - Reset the values of the given osnoise_variables
+ */
+static inline void osn_var_reset(void)
+{
+	struct osnoise_variables *osn_var;
+	int cpu;
+
+	/*
+	 * So far, all the values are initialized as 0, so
+	 * zeroing the structure is perfect.
+	 */
+	for_each_cpu(cpu, cpu_online_mask) {
+		osn_var = per_cpu_ptr(&per_cpu_osnoise_var, cpu);
+		memset(osn_var, 0, sizeof(*osn_var));
+	}
+}
+
+/*
+ * osn_var_reset_all - Reset the value of all per-cpu osnoise_variables
+ */
+static inline void osn_var_reset_all(void)
+{
+	osn_var_reset();
+	tlat_var_reset();
+}
+
+/*
+ * Tells NMIs to call back to the osnoise tracer to record timestamps.
+ */
+bool trace_osnoise_callback_enabled;
+
+/*
+ * osnoise sample structure definition. Used to store the statistics of a
+ * sample run.
+ */
+struct osnoise_sample {
+	u64			runtime;	/* runtime */
+	u64			noise;		/* noise */
+	u64			max_sample;	/* max single noise sample */
+	int			hw_count;	/* # HW (incl. hypervisor) interference */
+	int			nmi_count;	/* # NMIs during this sample */
+	int			irq_count;	/* # IRQs during this sample */
+	int			softirq_count;	/* # softirqs during this sample */
+	int			thread_count;	/* # threads during this sample */
+};
+
+#ifdef CONFIG_TIMERLAT_TRACER
+/*
+ * timerlat sample structure definition. Used to store the statistics of
+ * a sample run.
+ */
+struct timerlat_sample {
+	u64			timer_latency;	/* timer_latency */
+	unsigned int		seqnum;		/* unique sequence */
+	int			context;	/* timer context */
+};
+#endif
+
+/*
+ * Protect the interface.
+ */
+struct mutex interface_lock;
+
+/*
+ * Tracer data.
+ */
+static struct osnoise_data {
+	u64	sample_period;		/* total sampling period */
+	u64	sample_runtime;		/* active sampling portion of period */
+	u64	stop_tracing;		/* stop trace in the internal operation (loop/irq) */
+	u64	stop_tracing_total;	/* stop trace in the final operation (report/thread) */
+#ifdef CONFIG_TIMERLAT_TRACER
+	u64	timerlat_period;	/* timerlat period */
+	u64	print_stack;		/* print IRQ stack if total > */
+	int	timerlat_tracer;	/* timerlat tracer */
+#endif
+	bool	tainted;		/* infor users and developers about a problem */
+} osnoise_data = {
+	.sample_period			= DEFAULT_SAMPLE_PERIOD,
+	.sample_runtime			= DEFAULT_SAMPLE_RUNTIME,
+	.stop_tracing			= 0,
+	.stop_tracing_total		= 0,
+#ifdef CONFIG_TIMERLAT_TRACER
+	.print_stack			= 0,
+	.timerlat_period		= DEFAULT_TIMERLAT_PERIOD,
+	.timerlat_tracer		= 0,
+#endif
+};
+
+/*
+ * Boolean variable used to inform that the tracer is currently sampling.
+ */
+static bool osnoise_busy;
+
+/*
+ * Print the osnoise header info.
+ */
+static void print_osnoise_headers(struct seq_file *s)
+{
+	if (osnoise_data.tainted)
+		seq_puts(s, "# osnoise is tainted!\n");
+
+	seq_puts(s, "#                                _-----=> irqs-off\n");
+	seq_puts(s, "#                               / _----=> need-resched\n");
+	seq_puts(s, "#                              | / _---=> hardirq/softirq\n");
+	seq_puts(s, "#                              || / _--=> preempt-depth     ");
+	seq_puts(s, "                       MAX\n");
+
+	seq_puts(s, "#                              || /                         ");
+	seq_puts(s, "                    SINGLE      Interference counters:\n");
+
+	seq_puts(s, "#                              ||||               RUNTIME   ");
+	seq_puts(s, "   NOISE  %% OF CPU  NOISE    +-----------------------------+\n");
+
+	seq_puts(s, "#           TASK-PID      CPU# ||||   TIMESTAMP    IN US    ");
+	seq_puts(s, "   IN US  AVAILABLE  IN US     HW    NMI    IRQ   SIRQ THREAD\n");
+
+	seq_puts(s, "#              | |         |   ||||      |           |      ");
+	seq_puts(s, "       |    |            |      |      |      |      |      |\n");
+}
+
+/*
+ * osnoise_taint - report an osnoise error.
+ */
+#define osnoise_taint(msg) ({							\
+	struct trace_array *tr = osnoise_trace;					\
+										\
+	trace_array_printk_buf(tr->array_buffer.buffer, _THIS_IP_, msg);	\
+	osnoise_data.tainted = true;						\
+})
+
+/*
+ * Record an osnoise_sample into the tracer buffer.
+ */
+static void trace_osnoise_sample(struct osnoise_sample *sample)
+{
+	struct trace_array *tr = osnoise_trace;
+	struct trace_buffer *buffer = tr->array_buffer.buffer;
+	struct trace_event_call *call = &event_osnoise;
+	struct ring_buffer_event *event;
+	struct osnoise_entry *entry;
+
+	event = trace_buffer_lock_reserve(buffer, TRACE_OSNOISE, sizeof(*entry),
+					  tracing_gen_ctx());
+	if (!event)
+		return;
+	entry	= ring_buffer_event_data(event);
+	entry->runtime		= sample->runtime;
+	entry->noise		= sample->noise;
+	entry->max_sample	= sample->max_sample;
+	entry->hw_count		= sample->hw_count;
+	entry->nmi_count	= sample->nmi_count;
+	entry->irq_count	= sample->irq_count;
+	entry->softirq_count	= sample->softirq_count;
+	entry->thread_count	= sample->thread_count;
+
+	if (!call_filter_check_discard(call, entry, buffer, event))
+		trace_buffer_unlock_commit_nostack(buffer, event);
+}
+
+#ifdef CONFIG_TIMERLAT_TRACER
+/*
+ * Print the timerlat header info.
+ */
+static void print_timerlat_headers(struct seq_file *s)
+{
+	seq_puts(s, "#                                _-----=> irqs-off\n");
+	seq_puts(s, "#                               / _----=> need-resched\n");
+	seq_puts(s, "#                              | / _---=> hardirq/softirq\n");
+	seq_puts(s, "#                              || / _--=> preempt-depth\n");
+	seq_puts(s, "#                              || /\n");
+	seq_puts(s, "#                              ||||             ACTIVATION\n");
+	seq_puts(s, "#           TASK-PID      CPU# ||||   TIMESTAMP    ID     ");
+	seq_puts(s, "       CONTEXT                LATENCY\n");
+	seq_puts(s, "#              | |         |   ||||      |         |      ");
+	seq_puts(s, "            |                       |\n");
+}
+
+/*
+ * Record an timerlat_sample into the tracer buffer.
+ */
+static void trace_timerlat_sample(struct timerlat_sample *sample)
+{
+	struct trace_array *tr = osnoise_trace;
+	struct trace_event_call *call = &event_osnoise;
+	struct trace_buffer *buffer = tr->array_buffer.buffer;
+	struct ring_buffer_event *event;
+	struct timerlat_entry *entry;
+
+	event = trace_buffer_lock_reserve(buffer, TRACE_TIMERLAT, sizeof(*entry),
+					  tracing_gen_ctx());
+	if (!event)
+		return;
+	entry	= ring_buffer_event_data(event);
+	entry->seqnum			= sample->seqnum;
+	entry->context			= sample->context;
+	entry->timer_latency		= sample->timer_latency;
+
+	if (!call_filter_check_discard(call, entry, buffer, event))
+		trace_buffer_unlock_commit_nostack(buffer, event);
+}
+
+#ifdef CONFIG_STACKTRACE
+
+#define	MAX_CALLS	256
+
+/*
+ * Stack trace will take place only at IRQ level, so, no need
+ * to control nesting here.
+ */
+struct trace_stack {
+	int		stack_size;
+	int		nr_entries;
+	unsigned long	calls[MAX_CALLS];
+};
+
+static DEFINE_PER_CPU(struct trace_stack, trace_stack);
+
+/*
+ * timerlat_save_stack - save a stack trace without printing
+ *
+ * Save the current stack trace without printing. The
+ * stack will be printed later, after the end of the measurement.
+ */
+static void timerlat_save_stack(int skip)
+{
+	unsigned int size, nr_entries;
+	struct trace_stack *fstack;
+
+	fstack = this_cpu_ptr(&trace_stack);
+
+	size = ARRAY_SIZE(fstack->calls);
+
+	nr_entries = stack_trace_save(fstack->calls, size, skip);
+
+	fstack->stack_size = nr_entries * sizeof(unsigned long);
+	fstack->nr_entries = nr_entries;
+
+	return;
+
+}
+/*
+ * timerlat_dump_stack - dump a stack trace previously saved
+ *
+ * Dump a saved stack trace into the trace buffer.
+ */
+static void timerlat_dump_stack(void)
+{
+	struct trace_event_call *call = &event_osnoise;
+	struct trace_array *tr = osnoise_trace;
+	struct trace_buffer *buffer = tr->array_buffer.buffer;
+	struct ring_buffer_event *event;
+	struct trace_stack *fstack;
+	struct stack_entry *entry;
+	unsigned int size;
+
+	preempt_disable_notrace();
+	fstack = this_cpu_ptr(&trace_stack);
+	size = fstack->stack_size;
+
+	event = trace_buffer_lock_reserve(buffer, TRACE_STACK, sizeof(*entry) + size,
+					  tracing_gen_ctx());
+	if (!event)
+		goto out;
+
+	entry = ring_buffer_event_data(event);
+
+	memcpy(&entry->caller, fstack->calls, size);
+	entry->size = fstack->nr_entries;
+
+	if (!call_filter_check_discard(call, entry, buffer, event))
+		trace_buffer_unlock_commit_nostack(buffer, event);
+
+out:
+	preempt_enable_notrace();
+}
+#else
+#define timerlat_dump_stack() do {} while (0)
+#define timerlat_save_stack(a) do {} while (0)
+#endif /* CONFIG_STACKTRACE */
+#endif /* CONFIG_TIMERLAT_TRACER */
+
+/*
+ * Macros to encapsulate the time capturing infrastructure.
+ */
+#define time_get()	trace_clock_local()
+#define time_to_us(x)	div_u64(x, 1000)
+#define time_sub(a, b)	((a) - (b))
+
+/*
+ * cond_move_irq_delta_start - Forward the delta_start of a running IRQ
+ *
+ * If an IRQ is preempted by an NMI, its delta_start is pushed forward
+ * to discount the NMI interference.
+ *
+ * See get_int_safe_duration().
+ */
+static inline void
+cond_move_irq_delta_start(struct osnoise_variables *osn_var, u64 duration)
+{
+	if (osn_var->irq.delta_start)
+		osn_var->irq.delta_start += duration;
+}
+
+#ifndef CONFIG_PREEMPT_RT
+/*
+ * cond_move_softirq_delta_start - Forward the delta_start of a running softirq.
+ *
+ * If a softirq is preempted by an IRQ or NMI, its delta_start is pushed
+ * forward to discount the interference.
+ *
+ * See get_int_safe_duration().
+ */
+static inline void
+cond_move_softirq_delta_start(struct osnoise_variables *osn_var, u64 duration)
+{
+	if (osn_var->softirq.delta_start)
+		osn_var->softirq.delta_start += duration;
+}
+#else /* CONFIG_PREEMPT_RT */
+#define cond_move_softirq_delta_start(osn_var, duration) do {} while (0)
+#endif
+
+/*
+ * cond_move_thread_delta_start - Forward the delta_start of a running thread
+ *
+ * If a noisy thread is preempted by an softirq, IRQ or NMI, its delta_start
+ * is pushed forward to discount the interference.
+ *
+ * See get_int_safe_duration().
+ */
+static inline void
+cond_move_thread_delta_start(struct osnoise_variables *osn_var, u64 duration)
+{
+	if (osn_var->thread.delta_start)
+		osn_var->thread.delta_start += duration;
+}
+
+/*
+ * get_int_safe_duration - Get the duration of a window
+ *
+ * The irq, softirq and thread varaibles need to have its duration without
+ * the interference from higher priority interrupts. Instead of keeping a
+ * variable to discount the interrupt interference from these variables, the
+ * starting time of these variables are pushed forward with the interrupt's
+ * duration. In this way, a single variable is used to:
+ *
+ *   - Know if a given window is being measured.
+ *   - Account its duration.
+ *   - Discount the interference.
+ *
+ * To avoid getting inconsistent values, e.g.,:
+ *
+ *	now = time_get()
+ *		--->	interrupt!
+ *			delta_start -= int duration;
+ *		<---
+ *	duration = now - delta_start;
+ *
+ *	result: negative duration if the variable duration before the
+ *	interrupt was smaller than the interrupt execution.
+ *
+ * A counter of interrupts is used. If the counter increased, try
+ * to capture an interference safe duration.
+ */
+static inline s64
+get_int_safe_duration(struct osnoise_variables *osn_var, u64 *delta_start)
+{
+	u64 int_counter, now;
+	s64 duration;
+
+	do {
+		int_counter = local_read(&osn_var->int_counter);
+		/* synchronize with interrupts */
+		barrier();
+
+		now = time_get();
+		duration = (now - *delta_start);
+
+		/* synchronize with interrupts */
+		barrier();
+	} while (int_counter != local_read(&osn_var->int_counter));
+
+	/*
+	 * This is an evidence of race conditions that cause
+	 * a value to be "discounted" too much.
+	 */
+	if (duration < 0)
+		osnoise_taint("Negative duration!\n");
+
+	*delta_start = 0;
+
+	return duration;
+}
+
+/*
+ *
+ * set_int_safe_time - Save the current time on *time, aware of interference
+ *
+ * Get the time, taking into consideration a possible interference from
+ * higher priority interrupts.
+ *
+ * See get_int_safe_duration() for an explanation.
+ */
+static u64
+set_int_safe_time(struct osnoise_variables *osn_var, u64 *time)
+{
+	u64 int_counter;
+
+	do {
+		int_counter = local_read(&osn_var->int_counter);
+		/* synchronize with interrupts */
+		barrier();
+
+		*time = time_get();
+
+		/* synchronize with interrupts */
+		barrier();
+	} while (int_counter != local_read(&osn_var->int_counter));
+
+	return int_counter;
+}
+
+#ifdef CONFIG_TIMERLAT_TRACER
+/*
+ * copy_int_safe_time - Copy *src into *desc aware of interference
+ */
+static u64
+copy_int_safe_time(struct osnoise_variables *osn_var, u64 *dst, u64 *src)
+{
+	u64 int_counter;
+
+	do {
+		int_counter = local_read(&osn_var->int_counter);
+		/* synchronize with interrupts */
+		barrier();
+
+		*dst = *src;
+
+		/* synchronize with interrupts */
+		barrier();
+	} while (int_counter != local_read(&osn_var->int_counter));
+
+	return int_counter;
+}
+#endif /* CONFIG_TIMERLAT_TRACER */
+
+/*
+ * trace_osnoise_callback - NMI entry/exit callback
+ *
+ * This function is called at the entry and exit NMI code. The bool enter
+ * distinguishes between either case. This function is used to note a NMI
+ * occurrence, compute the noise caused by the NMI, and to remove the noise
+ * it is potentially causing on other interference variables.
+ */
+void trace_osnoise_callback(bool enter)
+{
+	struct osnoise_variables *osn_var = this_cpu_osn_var();
+	u64 duration;
+
+	if (!osn_var->sampling)
+		return;
+
+	/*
+	 * Currently trace_clock_local() calls sched_clock() and the
+	 * generic version is not NMI safe.
+	 */
+	if (!IS_ENABLED(CONFIG_GENERIC_SCHED_CLOCK)) {
+		if (enter) {
+			osn_var->nmi.delta_start = time_get();
+			local_inc(&osn_var->int_counter);
+		} else {
+			duration = time_get() - osn_var->nmi.delta_start;
+
+			trace_nmi_noise(osn_var->nmi.delta_start, duration);
+
+			cond_move_irq_delta_start(osn_var, duration);
+			cond_move_softirq_delta_start(osn_var, duration);
+			cond_move_thread_delta_start(osn_var, duration);
+		}
+	}
+
+	if (enter)
+		osn_var->nmi.count++;
+}
+
+/*
+ * osnoise_trace_irq_entry - Note the starting of an IRQ
+ *
+ * Save the starting time of an IRQ. As IRQs are non-preemptive to other IRQs,
+ * it is safe to use a single variable (ons_var->irq) to save the statistics.
+ * The arrival_time is used to report... the arrival time. The delta_start
+ * is used to compute the duration at the IRQ exit handler. See
+ * cond_move_irq_delta_start().
+ */
+void osnoise_trace_irq_entry(int id)
+{
+	struct osnoise_variables *osn_var = this_cpu_osn_var();
+
+	if (!osn_var->sampling)
+		return;
+	/*
+	 * This value will be used in the report, but not to compute
+	 * the execution time, so it is safe to get it unsafe.
+	 */
+	osn_var->irq.arrival_time = time_get();
+	set_int_safe_time(osn_var, &osn_var->irq.delta_start);
+	osn_var->irq.count++;
+
+	local_inc(&osn_var->int_counter);
+}
+
+/*
+ * osnoise_irq_exit - Note the end of an IRQ, sava data and trace
+ *
+ * Computes the duration of the IRQ noise, and trace it. Also discounts the
+ * interference from other sources of noise could be currently being accounted.
+ */
+void osnoise_trace_irq_exit(int id, const char *desc)
+{
+	struct osnoise_variables *osn_var = this_cpu_osn_var();
+	int duration;
+
+	if (!osn_var->sampling)
+		return;
+
+	duration = get_int_safe_duration(osn_var, &osn_var->irq.delta_start);
+	trace_irq_noise(id, desc, osn_var->irq.arrival_time, duration);
+	osn_var->irq.arrival_time = 0;
+	cond_move_softirq_delta_start(osn_var, duration);
+	cond_move_thread_delta_start(osn_var, duration);
+}
+
+/*
+ * trace_irqentry_callback - Callback to the irq:irq_entry traceevent
+ *
+ * Used to note the starting of an IRQ occurece.
+ */
+static void trace_irqentry_callback(void *data, int irq,
+				    struct irqaction *action)
+{
+	osnoise_trace_irq_entry(irq);
+}
+
+/*
+ * trace_irqexit_callback - Callback to the irq:irq_exit traceevent
+ *
+ * Used to note the end of an IRQ occurece.
+ */
+static void trace_irqexit_callback(void *data, int irq,
+				   struct irqaction *action, int ret)
+{
+	osnoise_trace_irq_exit(irq, action->name);
+}
+
+/*
+ * arch specific register function.
+ */
+int __weak osnoise_arch_register(void)
+{
+	return 0;
+}
+
+/*
+ * arch specific unregister function.
+ */
+void __weak osnoise_arch_unregister(void)
+{
+	return;
+}
+
+/*
+ * hook_irq_events - Hook IRQ handling events
+ *
+ * This function hooks the IRQ related callbacks to the respective trace
+ * events.
+ */
+static int hook_irq_events(void)
+{
+	int ret;
+
+	ret = register_trace_irq_handler_entry(trace_irqentry_callback, NULL);
+	if (ret)
+		goto out_err;
+
+	ret = register_trace_irq_handler_exit(trace_irqexit_callback, NULL);
+	if (ret)
+		goto out_unregister_entry;
+
+	ret = osnoise_arch_register();
+	if (ret)
+		goto out_irq_exit;
+
+	return 0;
+
+out_irq_exit:
+	unregister_trace_irq_handler_exit(trace_irqexit_callback, NULL);
+out_unregister_entry:
+	unregister_trace_irq_handler_entry(trace_irqentry_callback, NULL);
+out_err:
+	return -EINVAL;
+}
+
+/*
+ * unhook_irq_events - Unhook IRQ handling events
+ *
+ * This function unhooks the IRQ related callbacks to the respective trace
+ * events.
+ */
+static void unhook_irq_events(void)
+{
+	osnoise_arch_unregister();
+	unregister_trace_irq_handler_exit(trace_irqexit_callback, NULL);
+	unregister_trace_irq_handler_entry(trace_irqentry_callback, NULL);
+}
+
+#ifndef CONFIG_PREEMPT_RT
+/*
+ * trace_softirq_entry_callback - Note the starting of a softirq
+ *
+ * Save the starting time of a softirq. As softirqs are non-preemptive to
+ * other softirqs, it is safe to use a single variable (ons_var->softirq)
+ * to save the statistics. The arrival_time is used to report... the
+ * arrival time. The delta_start is used to compute the duration at the
+ * softirq exit handler. See cond_move_softirq_delta_start().
+ */
+static void trace_softirq_entry_callback(void *data, unsigned int vec_nr)
+{
+	struct osnoise_variables *osn_var = this_cpu_osn_var();
+
+	if (!osn_var->sampling)
+		return;
+	/*
+	 * This value will be used in the report, but not to compute
+	 * the execution time, so it is safe to get it unsafe.
+	 */
+	osn_var->softirq.arrival_time = time_get();
+	set_int_safe_time(osn_var, &osn_var->softirq.delta_start);
+	osn_var->softirq.count++;
+
+	local_inc(&osn_var->int_counter);
+}
+
+/*
+ * trace_softirq_exit_callback - Note the end of an softirq
+ *
+ * Computes the duration of the softirq noise, and trace it. Also discounts the
+ * interference from other sources of noise could be currently being accounted.
+ */
+static void trace_softirq_exit_callback(void *data, unsigned int vec_nr)
+{
+	struct osnoise_variables *osn_var = this_cpu_osn_var();
+	int duration;
+
+	if (!osn_var->sampling)
+		return;
+
+#ifdef CONFIG_TIMERLAT_TRACER
+	/*
+	 * If the timerlat is enabled, but the irq handler did
+	 * not run yet enabling timerlat_tracer, do not trace.
+	 */
+	if (unlikely(osnoise_data.timerlat_tracer)) {
+		struct timerlat_variables *tlat_var;
+		tlat_var = this_cpu_tmr_var();
+		if (!tlat_var->tracing_thread) {
+			osn_var->softirq.arrival_time = 0;
+			osn_var->softirq.delta_start = 0;
+			return;
+		}
+	}
+#endif
+
+	duration = get_int_safe_duration(osn_var, &osn_var->softirq.delta_start);
+	trace_softirq_noise(vec_nr, osn_var->softirq.arrival_time, duration);
+	cond_move_thread_delta_start(osn_var, duration);
+	osn_var->softirq.arrival_time = 0;
+}
+
+/*
+ * hook_softirq_events - Hook softirq handling events
+ *
+ * This function hooks the softirq related callbacks to the respective trace
+ * events.
+ */
+static int hook_softirq_events(void)
+{
+	int ret;
+
+	ret = register_trace_softirq_entry(trace_softirq_entry_callback, NULL);
+	if (ret)
+		goto out_err;
+
+	ret = register_trace_softirq_exit(trace_softirq_exit_callback, NULL);
+	if (ret)
+		goto out_unreg_entry;
+
+	return 0;
+
+out_unreg_entry:
+	unregister_trace_softirq_entry(trace_softirq_entry_callback, NULL);
+out_err:
+	return -EINVAL;
+}
+
+/*
+ * unhook_softirq_events - Unhook softirq handling events
+ *
+ * This function hooks the softirq related callbacks to the respective trace
+ * events.
+ */
+static void unhook_softirq_events(void)
+{
+	unregister_trace_softirq_entry(trace_softirq_entry_callback, NULL);
+	unregister_trace_softirq_exit(trace_softirq_exit_callback, NULL);
+}
+#else /* CONFIG_PREEMPT_RT */
+/*
+ * softirq are threads on the PREEMPT_RT mode.
+ */
+static int hook_softirq_events(void)
+{
+	return 0;
+}
+static void unhook_softirq_events(void)
+{
+}
+#endif
+
+/*
+ * thread_entry - Record the starting of a thread noise window
+ *
+ * It saves the context switch time for a noisy thread, and increments
+ * the interference counters.
+ */
+static void
+thread_entry(struct osnoise_variables *osn_var, struct task_struct *t)
+{
+	if (!osn_var->sampling)
+		return;
+	/*
+	 * The arrival time will be used in the report, but not to compute
+	 * the execution time, so it is safe to get it unsafe.
+	 */
+	osn_var->thread.arrival_time = time_get();
+
+	set_int_safe_time(osn_var, &osn_var->thread.delta_start);
+
+	osn_var->thread.count++;
+	local_inc(&osn_var->int_counter);
+}
+
+/*
+ * thread_exit - Report the end of a thread noise window
+ *
+ * It computes the total noise from a thread, tracing if needed.
+ */
+static void
+thread_exit(struct osnoise_variables *osn_var, struct task_struct *t)
+{
+	int duration;
+
+	if (!osn_var->sampling)
+		return;
+
+#ifdef CONFIG_TIMERLAT_TRACER
+	if (osnoise_data.timerlat_tracer) {
+		struct timerlat_variables *tlat_var;
+		tlat_var = this_cpu_tmr_var();
+		if (!tlat_var->tracing_thread) {
+			osn_var->thread.delta_start = 0;
+			osn_var->thread.arrival_time = 0;
+			return;
+		}
+	}
+#endif
+
+	duration = get_int_safe_duration(osn_var, &osn_var->thread.delta_start);
+
+	trace_thread_noise(t, osn_var->thread.arrival_time, duration);
+
+	osn_var->thread.arrival_time = 0;
+}
+
+/*
+ * trace_sched_switch - sched:sched_switch trace event handler
+ *
+ * This function is hooked to the sched:sched_switch trace event, and it is
+ * used to record the beginning and to report the end of a thread noise window.
+ */
+static void
+trace_sched_switch_callback(void *data, bool preempt, struct task_struct *p,
+			    struct task_struct *n)
+{
+	struct osnoise_variables *osn_var = this_cpu_osn_var();
+
+	if (p->pid != osn_var->pid)
+		thread_exit(osn_var, p);
+
+	if (n->pid != osn_var->pid)
+		thread_entry(osn_var, n);
+}
+
+/*
+ * hook_thread_events - Hook the insturmentation for thread noise
+ *
+ * Hook the osnoise tracer callbacks to handle the noise from other
+ * threads on the necessary kernel events.
+ */
+static int hook_thread_events(void)
+{
+	int ret;
+
+	ret = register_trace_sched_switch(trace_sched_switch_callback, NULL);
+	if (ret)
+		return -EINVAL;
+
+	return 0;
+}
+
+/*
+ * unhook_thread_events - *nhook the insturmentation for thread noise
+ *
+ * Unook the osnoise tracer callbacks to handle the noise from other
+ * threads on the necessary kernel events.
+ */
+static void unhook_thread_events(void)
+{
+	unregister_trace_sched_switch(trace_sched_switch_callback, NULL);
+}
+
+/*
+ * save_osn_sample_stats - Save the osnoise_sample statistics
+ *
+ * Save the osnoise_sample statistics before the sampling phase. These
+ * values will be used later to compute the diff betwneen the statistics
+ * before and after the osnoise sampling.
+ */
+static void
+save_osn_sample_stats(struct osnoise_variables *osn_var, struct osnoise_sample *s)
+{
+	s->nmi_count = osn_var->nmi.count;
+	s->irq_count = osn_var->irq.count;
+	s->softirq_count = osn_var->softirq.count;
+	s->thread_count = osn_var->thread.count;
+}
+
+/*
+ * diff_osn_sample_stats - Compute the osnoise_sample statistics
+ *
+ * After a sample period, compute the difference on the osnoise_sample
+ * statistics. The struct osnoise_sample *s contains the statistics saved via
+ * save_osn_sample_stats() before the osnoise sampling.
+ */
+static void
+diff_osn_sample_stats(struct osnoise_variables *osn_var, struct osnoise_sample *s)
+{
+	s->nmi_count = osn_var->nmi.count - s->nmi_count;
+	s->irq_count = osn_var->irq.count - s->irq_count;
+	s->softirq_count = osn_var->softirq.count - s->softirq_count;
+	s->thread_count = osn_var->thread.count - s->thread_count;
+}
+
+/*
+ * osnoise_stop_tracing - Stop tracing and the tracer.
+ */
+static void osnoise_stop_tracing(void)
+{
+	struct trace_array *tr = osnoise_trace;
+	tracer_tracing_off(tr);
+}
+
+/*
+ * run_osnoise - Sample the time and look for osnoise
+ *
+ * Used to capture the time, looking for potential osnoise latency repeatedly.
+ * Different from hwlat_detector, it is called with preemption and interrupts
+ * enabled. This allows irqs, softirqs and threads to run, interfering on the
+ * osnoise sampling thread, as they would do with a regular thread.
+ */
+static int run_osnoise(void)
+{
+	struct osnoise_variables *osn_var = this_cpu_osn_var();
+	struct trace_array *tr = osnoise_trace;
+	u64 start, sample, last_sample;
+	u64 last_int_count, int_count;
+	s64 noise = 0, max_noise = 0;
+	s64 total, last_total = 0;
+	struct osnoise_sample s;
+	unsigned int threshold;
+	u64 runtime, stop_in;
+	u64 sum_noise = 0;
+	int hw_count = 0;
+	int ret = -1;
+
+	/*
+	 * Considers the current thread as the workload.
+	 */
+	osn_var->pid = current->pid;
+
+	/*
+	 * Save the current stats for the diff
+	 */
+	save_osn_sample_stats(osn_var, &s);
+
+	/*
+	 * if threshold is 0, use the default value of 5 us.
+	 */
+	threshold = tracing_thresh ? : 5000;
+
+	/*
+	 * Make sure NMIs see sampling first
+	 */
+	osn_var->sampling = true;
+	barrier();
+
+	/*
+	 * Transform the *_us config to nanoseconds to avoid the
+	 * division on the main loop.
+	 */
+	runtime = osnoise_data.sample_runtime * NSEC_PER_USEC;
+	stop_in = osnoise_data.stop_tracing * NSEC_PER_USEC;
+
+	/*
+	 * Start timestemp
+	 */
+	start = time_get();
+
+	/*
+	 * "previous" loop.
+	 */
+	last_int_count = set_int_safe_time(osn_var, &last_sample);
+
+	do {
+		/*
+		 * Get sample!
+		 */
+		int_count = set_int_safe_time(osn_var, &sample);
+
+		noise = time_sub(sample, last_sample);
+
+		/*
+		 * This shouldn't happen.
+		 */
+		if (noise < 0) {
+			osnoise_taint("negative noise!");
+			goto out;
+		}
+
+		/*
+		 * Sample runtime.
+		 */
+		total = time_sub(sample, start);
+
+		/*
+		 * Check for possible overflows.
+		 */
+		if (total < last_total) {
+			osnoise_taint("total overflow!");
+			break;
+		}
+
+		last_total = total;
+
+		if (noise >= threshold) {
+			int interference = int_count - last_int_count;
+
+			if (noise > max_noise)
+				max_noise = noise;
+
+			if (!interference)
+				hw_count++;
+
+			sum_noise += noise;
+
+			trace_sample_threshold(last_sample, noise, interference);
+
+			if (osnoise_data.stop_tracing)
+				if (noise > stop_in)
+					osnoise_stop_tracing();
+		}
+
+		/*
+		 * For the non-preemptive kernel config: let threads runs, if
+		 * they so wish.
+		 */
+		cond_resched();
+
+		last_sample = sample;
+		last_int_count = int_count;
+
+	} while (total < runtime && !kthread_should_stop());
+
+	/*
+	 * Finish the above in the view for interrupts.
+	 */
+	barrier();
+
+	osn_var->sampling = false;
+
+	/*
+	 * Make sure sampling data is no longer updated.
+	 */
+	barrier();
+
+	/*
+	 * Save noise info.
+	 */
+	s.noise = time_to_us(sum_noise);
+	s.runtime = time_to_us(total);
+	s.max_sample = time_to_us(max_noise);
+	s.hw_count = hw_count;
+
+	/* Save interference stats info */
+	diff_osn_sample_stats(osn_var, &s);
+
+	trace_osnoise_sample(&s);
+
+	/* Keep a running maximum ever recorded osnoise "latency" */
+	if (max_noise > tr->max_latency) {
+		tr->max_latency = max_noise;
+		latency_fsnotify(tr);
+	}
+
+	if (osnoise_data.stop_tracing_total)
+		if (s.noise > osnoise_data.stop_tracing_total)
+			osnoise_stop_tracing();
+
+	return 0;
+out:
+	return ret;
+}
+
+static struct cpumask osnoise_cpumask;
+static struct cpumask save_cpumask;
+
+/*
+ * osnoise_main - The osnoise detection kernel thread
+ *
+ * Calls run_osnoise() function to measure the osnoise for the configured runtime,
+ * every period.
+ */
+static int osnoise_main(void *data)
+{
+	u64 interval;
+
+	while (!kthread_should_stop()) {
+
+		run_osnoise();
+
+		mutex_lock(&interface_lock);
+		interval = osnoise_data.sample_period - osnoise_data.sample_runtime;
+		mutex_unlock(&interface_lock);
+
+		do_div(interval, USEC_PER_MSEC);
+
+		/*
+		 * differently from hwlat_detector, the osnoise tracer can run
+		 * without a pause because preemption is on.
+		 */
+		if (interval < 1) {
+			/* Let synchronize_rcu_tasks() make progress */
+			cond_resched_tasks_rcu_qs();
+			continue;
+		}
+
+		if (msleep_interruptible(interval))
+			break;
+	}
+
+	return 0;
+}
+
+#ifdef CONFIG_TIMERLAT_TRACER
+/*
+ * timerlat_irq - hrtimer handler for timerlat.
+ */
+static enum hrtimer_restart timerlat_irq(struct hrtimer *timer)
+{
+	struct osnoise_variables *osn_var = this_cpu_osn_var();
+	struct trace_array *tr = osnoise_trace;
+	struct timerlat_variables *tlat;
+	struct timerlat_sample s;
+	u64 now;
+	u64 diff;
+
+	/*
+	 * I am not sure if the timer was armed for this CPU. So, get
+	 * the timerlat struct from the timer itself, not from this
+	 * CPU.
+	 */
+	tlat = container_of(timer, struct timerlat_variables, timer);
+
+	now = ktime_to_ns(hrtimer_cb_get_time(&tlat->timer));
+
+	/*
+	 * Enable the osnoise: events for thread an softirq.
+	 */
+	tlat->tracing_thread = true;
+
+	osn_var->thread.arrival_time = time_get();
+
+	/*
+	 * A hardirq is running: the timer IRQ. It is for sure preempting
+	 * a thread, and potentially preempting a softirq.
+	 *
+	 * At this point, it is not interesting to know the duration of the
+	 * preempted thread (and maybe softirq), but how much time they will
+	 * delay the beginning of the execution of the timer thread.
+	 *
+	 * To get the correct (net) delay added by the softirq, its delta_start
+	 * is set as the IRQ one. In this way, at the return of the IRQ, the delta
+	 * start of the sofitrq will be zeroed, accounting then only the time
+	 * after that.
+	 *
+	 * The thread follows the same principle. However, if a softirq is
+	 * running, the thread needs to receive the softirq delta_start. The
+	 * reason being is that the softirq will be the last to be unfolded,
+	 * resseting the thread delay to zero.
+	 */
+#ifndef CONFIG_PREEMPT_RT
+	if (osn_var->softirq.delta_start) {
+		copy_int_safe_time(osn_var, &osn_var->thread.delta_start,
+				   &osn_var->softirq.delta_start);
+
+		copy_int_safe_time(osn_var, &osn_var->softirq.delta_start,
+				    &osn_var->irq.delta_start);
+	} else {
+		copy_int_safe_time(osn_var, &osn_var->thread.delta_start,
+				    &osn_var->irq.delta_start);
+	}
+#else /* CONFIG_PREEMPT_RT */
+	/*
+	 * The sofirqs run as threads on RT, so there is not need
+	 * to keep track of it.
+	 */
+	copy_int_safe_time(osn_var, &osn_var->thread.delta_start, &osn_var->irq.delta_start);
+#endif /* CONFIG_PREEMPT_RT */
+
+	/*
+	 * Compute the current time with the expected time.
+	 */
+	diff = now - tlat->abs_period;
+
+	tlat->count++;
+	s.seqnum = tlat->count;
+	s.timer_latency = diff;
+	s.context = IRQ_CONTEXT;
+
+	trace_timerlat_sample(&s);
+
+	/* Keep a running maximum ever recorded os noise "latency" */
+	if (diff > tr->max_latency) {
+		tr->max_latency = diff;
+		latency_fsnotify(tr);
+	}
+
+	if (osnoise_data.stop_tracing)
+		if (time_to_us(diff) >= osnoise_data.stop_tracing)
+			osnoise_stop_tracing();
+
+	wake_up_process(tlat->kthread);
+
+	if (osnoise_data.print_stack)
+		timerlat_save_stack(0);
+
+	return HRTIMER_NORESTART;
+}
+
+/*
+ * wait_next_period - Wait for the next period for timerlat
+ */
+static int wait_next_period(struct timerlat_variables *tlat)
+{
+	ktime_t next_abs_period, now;
+	u64 rel_period = osnoise_data.timerlat_period * 1000;
+
+	now = hrtimer_cb_get_time(&tlat->timer);
+	next_abs_period = ns_to_ktime(tlat->abs_period + rel_period);
+
+	/*
+	 * Save the next abs_period.
+	 */
+	tlat->abs_period = (u64) ktime_to_ns(next_abs_period);
+
+	/*
+	 * If the new abs_period is in the past, skip the activation.
+	 */
+	while (ktime_compare(now, next_abs_period) > 0) {
+		next_abs_period = ns_to_ktime(tlat->abs_period + rel_period);
+		tlat->abs_period = (u64) ktime_to_ns(next_abs_period);
+	}
+
+	set_current_state(TASK_INTERRUPTIBLE);
+
+	hrtimer_start(&tlat->timer, next_abs_period, HRTIMER_MODE_ABS_PINNED_HARD);
+	schedule();
+	return 1;
+}
+
+/*
+ * timerlat_main- Timerlat main
+ */
+static int timerlat_main(void *data)
+{
+	struct osnoise_variables *osn_var = this_cpu_osn_var();
+	struct timerlat_variables *tlat = this_cpu_tmr_var();
+	struct timerlat_sample s;
+	struct sched_param sp;
+	u64 now, diff;
+
+	/*
+	 * Make the thread RT, that is how cyclictest is usually used.
+	 */
+	sp.sched_priority = DEFAULT_TIMERLAT_PRIO;
+	sched_setscheduler_nocheck(current, SCHED_FIFO, &sp);
+
+	tlat->count = 0;
+	tlat->tracing_thread = false;
+
+	hrtimer_init(&tlat->timer, CLOCK_MONOTONIC, HRTIMER_MODE_ABS_PINNED_HARD);
+	tlat->timer.function = timerlat_irq;
+	tlat->kthread = current;
+	osn_var->pid = current->pid;
+	/*
+	 * Anotate the arrival time.
+	 */
+	tlat->abs_period = hrtimer_cb_get_time(&tlat->timer);
+
+	wait_next_period(tlat);
+
+	osn_var->sampling = 1;
+
+	while (!kthread_should_stop()) {
+		now = ktime_to_ns(hrtimer_cb_get_time(&tlat->timer));
+		diff = now - tlat->abs_period;
+
+		s.seqnum = tlat->count;
+		s.timer_latency = diff;
+		s.context = THREAD_CONTEXT;
+
+		trace_timerlat_sample(&s);
+
+#ifdef CONFIG_STACKTRACE
+		if (osnoise_data.print_stack)
+			if (osnoise_data.print_stack <= time_to_us(diff))
+				timerlat_dump_stack();
+#endif /* CONFIG_STACKTRACE */
+
+		tlat->tracing_thread = false;
+		if (osnoise_data.stop_tracing_total)
+			if (time_to_us(diff) >= osnoise_data.stop_tracing_total)
+				osnoise_stop_tracing();
+
+		wait_next_period(tlat);
+	}
+
+	hrtimer_cancel(&tlat->timer);
+	return 0;
+}
+#endif /* CONFIG_TIMERLAT_TRACER */
+
+/*
+ * stop_kthread - stop a workload thread
+ */
+static void stop_kthread(unsigned int cpu)
+{
+	struct task_struct *kthread;
+
+	kthread = per_cpu(per_cpu_osnoise_var, cpu).kthread;
+	if (kthread)
+		kthread_stop(kthread);
+	per_cpu(per_cpu_osnoise_var, cpu).kthread = NULL;
+}
+
+/*
+ * stop_per_cpu_kthread - Stop per-cpu threads
+ *
+ * Stop the osnoise sampling htread. Use this on unload and at system
+ * shutdown.
+ */
+static void stop_per_cpu_kthreads(void)
+{
+	int cpu;
+
+	get_online_cpus();
+
+	for_each_online_cpu(cpu)
+		stop_kthread(cpu);
+
+	put_online_cpus();
+}
+
+/*
+ * start_kthread - Start a workload tread
+ */
+static int start_kthread(unsigned int cpu)
+{
+	struct task_struct *kthread;
+	void *main = osnoise_main;
+	char comm[24];
+
+#ifdef CONFIG_TIMERLAT_TRACER
+	if (osnoise_data.timerlat_tracer) {
+		snprintf(comm, 24, "timerlat/%d", cpu);
+		main = timerlat_main;
+	} else {
+		snprintf(comm, 24, "osnoise/%d", cpu);
+	}
+#else
+	snprintf(comm, 24, "osnoise/%d", cpu);
+#endif
+	kthread = kthread_create_on_cpu(main, NULL, cpu, comm);
+
+	if (IS_ERR(kthread)) {
+		pr_err(BANNER "could not start sampling thread\n");
+		stop_per_cpu_kthreads();
+		return -ENOMEM;
+	}
+
+	per_cpu(per_cpu_osnoise_var, cpu).kthread = kthread;
+	wake_up_process(kthread);
+
+	return 0;
+}
+
+/*
+ * start_per_cpu_kthread - Kick off per-cpu osnoise sampling kthreads
+ *
+ * This starts the kernel thread that will look for osnoise on many
+ * cpus.
+ */
+static int start_per_cpu_kthreads(struct trace_array *tr)
+{
+	struct cpumask *current_mask = &save_cpumask;
+	int retval;
+	int cpu;
+
+	get_online_cpus();
+	/*
+	 * Run only on CPUs in which trace and osnoise are allowed to run.
+	 */
+	cpumask_and(current_mask, tr->tracing_cpumask, &osnoise_cpumask);
+	/*
+	 * And the CPU is online.
+	 */
+	cpumask_and(current_mask, cpu_online_mask, current_mask);
+
+	for_each_possible_cpu(cpu)
+		per_cpu(per_cpu_osnoise_var, cpu).kthread = NULL;
+
+	for_each_cpu(cpu, current_mask) {
+		retval = start_kthread(cpu);
+		if (retval) {
+			stop_per_cpu_kthreads();
+			return retval;
+		}
+	}
+
+	put_online_cpus();
+
+	return 0;
+}
+
+#ifdef CONFIG_HOTPLUG_CPU
+static void osnoise_hotplug_workfn(struct work_struct *dummy)
+{
+	struct trace_array *tr = osnoise_trace;
+	unsigned int cpu = smp_processor_id();
+
+
+	mutex_lock(&trace_types_lock);
+
+	if (!osnoise_busy)
+		goto out_unlock_trace;
+
+	mutex_lock(&interface_lock);
+	get_online_cpus();
+
+	if (!cpumask_test_cpu(cpu, &osnoise_cpumask))
+		goto out_unlock;
+
+	if (!cpumask_test_cpu(cpu, tr->tracing_cpumask))
+		goto out_unlock;
+
+	start_kthread(cpu);
+
+out_unlock:
+	put_online_cpus();
+	mutex_unlock(&interface_lock);
+out_unlock_trace:
+	mutex_unlock(&trace_types_lock);
+}
+
+static DECLARE_WORK(osnoise_hotplug_work, osnoise_hotplug_workfn);
+
+/*
+ * osnoise_cpu_init - CPU hotplug online callback function
+ */
+static int osnoise_cpu_init(unsigned int cpu)
+{
+	schedule_work_on(cpu, &osnoise_hotplug_work);
+	return 0;
+}
+
+/*
+ * osnoise_cpu_die - CPU hotplug offline callback function
+ */
+static int osnoise_cpu_die(unsigned int cpu)
+{
+	stop_kthread(cpu);
+	return 0;
+}
+
+static void osnoise_init_hotplug_support(void)
+{
+	int ret;
+
+	ret = cpuhp_setup_state(CPUHP_AP_ONLINE_DYN, "trace/osnoise:online",
+				osnoise_cpu_init, osnoise_cpu_die);
+	if (ret < 0)
+		pr_warn(BANNER "Error to init cpu hotplug support\n");
+
+	return;
+}
+#else /* CONFIG_HOTPLUG_CPU */
+static void osnoise_init_hotplug_support(void)
+{
+	return;
+}
+#endif /* CONFIG_HOTPLUG_CPU */
+
+/*
+ * osnoise_cpus_read - Read function for reading the "cpus" file
+ * @filp: The active open file structure
+ * @ubuf: The userspace provided buffer to read value into
+ * @cnt: The maximum number of bytes to read
+ * @ppos: The current "file" position
+ *
+ * Prints the "cpus" output into the user-provided buffer.
+ */
+static ssize_t
+osnoise_cpus_read(struct file *filp, char __user *ubuf, size_t count,
+		  loff_t *ppos)
+{
+	char *mask_str;
+	int len;
+
+	mutex_lock(&interface_lock);
+
+	len = snprintf(NULL, 0, "%*pbl\n", cpumask_pr_args(&osnoise_cpumask)) + 1;
+	mask_str = kmalloc(len, GFP_KERNEL);
+	if (!mask_str) {
+		count = -ENOMEM;
+		goto out_unlock;
+	}
+
+	len = snprintf(mask_str, len, "%*pbl\n", cpumask_pr_args(&osnoise_cpumask));
+	if (len >= count) {
+		count = -EINVAL;
+		goto out_free;
+	}
+
+	count = simple_read_from_buffer(ubuf, count, ppos, mask_str, len);
+
+out_free:
+	kfree(mask_str);
+out_unlock:
+	mutex_unlock(&interface_lock);
+
+	return count;
+}
+
+static void osnoise_tracer_start(struct trace_array *tr);
+static void osnoise_tracer_stop(struct trace_array *tr);
+
+/*
+ * osnoise_cpus_write - Write function for "cpus" entry
+ * @filp: The active open file structure
+ * @ubuf: The user buffer that contains the value to write
+ * @cnt: The maximum number of bytes to write to "file"
+ * @ppos: The current position in @file
+ *
+ * This function provides a write implementation for the "cpus"
+ * interface to the osnoise trace. By default, it lists all  CPUs,
+ * in this way, allowing osnoise threads to run on any online CPU
+ * of the system. It serves to restrict the execution of osnoise to the
+ * set of CPUs writing via this interface. Note that osnoise also
+ * respects the "tracing_cpumask." Hence, osnoise threads will run only
+ * on the set of CPUs allowed here AND on "tracing_cpumask." Why not
+ * have just "tracing_cpumask?" Because the user might be interested
+ * in tracing what is running on other CPUs. For instance, one might
+ * run osnoise in one HT CPU while observing what is running on the
+ * sibling HT CPU.
+ */
+static ssize_t
+osnoise_cpus_write(struct file *filp, const char __user *ubuf, size_t count,
+		   loff_t *ppos)
+{
+	struct trace_array *tr = osnoise_trace;
+	cpumask_var_t osnoise_cpumask_new;
+	int running, err;
+	char buf[256];
+
+	if (count >= 256)
+		return -EINVAL;
+
+	if (copy_from_user(buf, ubuf, count))
+		return -EFAULT;
+
+	if (!zalloc_cpumask_var(&osnoise_cpumask_new, GFP_KERNEL))
+		return -ENOMEM;
+
+	err = cpulist_parse(buf, osnoise_cpumask_new);
+	if (err)
+		goto err_free;
+
+	/*
+	 * trace_types_lock is taken to avoid concurrency on start/stop
+	 * and osnoise_busy.
+	 */
+	mutex_lock(&trace_types_lock);
+	running = osnoise_busy;
+	if (running)
+		osnoise_tracer_stop(tr);
+
+	mutex_lock(&interface_lock);
+	/*
+	 * osnoise_cpumask is read by CPU hotplug operations.
+	 */
+	get_online_cpus();
+
+	cpumask_copy(&osnoise_cpumask, osnoise_cpumask_new);
+
+	put_online_cpus();
+	mutex_unlock(&interface_lock);
+
+	if (running)
+		osnoise_tracer_start(tr);
+	mutex_unlock(&trace_types_lock);
+
+	free_cpumask_var(osnoise_cpumask_new);
+	return count;
+
+err_free:
+	free_cpumask_var(osnoise_cpumask_new);
+
+	return err;
+}
+
+/*
+ * osnoise/runtime_us: cannot be greater than the period.
+ */
+static struct trace_min_max_param osnoise_runtime = {
+	.lock	= &interface_lock,
+	.val	= &osnoise_data.sample_runtime,
+	.max	= &osnoise_data.sample_period,
+	.min	= NULL,
+};
+
+/*
+ * osnoise/period_us: cannot be smaller than the runtime.
+ */
+static struct trace_min_max_param osnoise_period = {
+	.lock	= &interface_lock,
+	.val	= &osnoise_data.sample_period,
+	.max	= NULL,
+	.min	= &osnoise_data.sample_runtime,
+};
+
+/*
+ * osnoise/stop_tracing_us: no limit.
+ */
+static struct trace_min_max_param osnoise_stop_tracing_in = {
+	.lock	= &interface_lock,
+	.val	= &osnoise_data.stop_tracing,
+	.max	= NULL,
+	.min	= NULL,
+};
+
+/*
+ * osnoise/stop_tracing_total_us: no limit.
+ */
+static struct trace_min_max_param osnoise_stop_tracing_total = {
+	.lock	= &interface_lock,
+	.val	= &osnoise_data.stop_tracing_total,
+	.max	= NULL,
+	.min	= NULL,
+};
+
+#ifdef CONFIG_TIMERLAT_TRACER
+/*
+ * osnoise/print_stack: print the stacktrace of the IRQ handler if the total
+ * latency is higher than val.
+ */
+static struct trace_min_max_param osnoise_print_stack = {
+	.lock	= &interface_lock,
+	.val	= &osnoise_data.print_stack,
+	.max	= NULL,
+	.min	= NULL,
+};
+
+/*
+ * osnoise/timerlat_period: min 100 us, max 1 s
+ */
+u64 timerlat_min_period = 100;
+u64 timerlat_max_period = 1000000;
+static struct trace_min_max_param timerlat_period = {
+	.lock	= &interface_lock,
+	.val	= &osnoise_data.timerlat_period,
+	.max	= &timerlat_max_period,
+	.min	= &timerlat_min_period,
+};
+#endif
+
+static const struct file_operations cpus_fops = {
+	.open		= tracing_open_generic,
+	.read		= osnoise_cpus_read,
+	.write		= osnoise_cpus_write,
+	.llseek		= generic_file_llseek,
+};
+
+/*
+ * init_tracefs - A function to initialize the tracefs interface files
+ *
+ * This function creates entries in tracefs for "osnoise" and "timerlat".
+ * It creates these directories in the tracing directory, and within that
+ * directory the use can change and view the configs.
+ */
+static int init_tracefs(void)
+{
+	struct dentry *top_dir;
+	struct dentry *tmp;
+	int ret;
+
+	ret = tracing_init_dentry();
+	if (ret)
+		return -ENOMEM;
+
+	top_dir = tracefs_create_dir("osnoise", NULL);
+	if (!top_dir)
+		return 0;
+
+	tmp = tracefs_create_file("period_us", 0640, top_dir,
+				  &osnoise_period, &trace_min_max_fops);
+	if (!tmp)
+		goto err;
+
+	tmp = tracefs_create_file("runtime_us", 0644, top_dir,
+				  &osnoise_runtime, &trace_min_max_fops);
+	if (!tmp)
+		goto err;
+
+	tmp = tracefs_create_file("stop_tracing_us", 0640, top_dir,
+				  &osnoise_stop_tracing_in, &trace_min_max_fops);
+	if (!tmp)
+		goto err;
+
+	tmp = tracefs_create_file("stop_tracing_total_us", 0640, top_dir,
+				  &osnoise_stop_tracing_total, &trace_min_max_fops);
+	if (!tmp)
+		goto err;
+
+	tmp = trace_create_file("cpus", 0644, top_dir, NULL, &cpus_fops);
+	if (!tmp)
+		goto err;
+#ifdef CONFIG_TIMERLAT_TRACER
+#ifdef CONFIG_STACKTRACE
+	tmp = tracefs_create_file("print_stack", 0640, top_dir,
+				  &osnoise_print_stack, &trace_min_max_fops);
+	if (!tmp)
+		goto err;
+#endif
+
+	tmp = tracefs_create_file("timerlat_period_us", 0640, top_dir,
+				  &timerlat_period, &trace_min_max_fops);
+	if (!tmp)
+		goto err;
+#endif
+
+	return 0;
+
+err:
+	tracefs_remove(top_dir);
+	return -ENOMEM;
+}
+
+static int osnoise_hook_events(void)
+{
+	int retval;
+
+	/*
+	 * Trace is already hooked, we are re-enabling from
+	 * a stop_tracing_*.
+	 */
+	if (trace_osnoise_callback_enabled)
+		return 0;
+
+	retval = hook_irq_events();
+	if (retval)
+		return -EINVAL;
+
+	retval = hook_softirq_events();
+	if (retval)
+		goto out_unhook_irq;
+
+	retval = hook_thread_events();
+	/*
+	 * All fine!
+	 */
+	if (!retval)
+		return 0;
+
+	unhook_softirq_events();
+out_unhook_irq:
+	unhook_irq_events();
+	return -EINVAL;
+}
+
+static int __osnoise_tracer_start(struct trace_array *tr)
+{
+	int retval;
+
+	osn_var_reset_all();
+
+	retval = osnoise_hook_events();
+	if (retval)
+		return retval;
+	/*
+	 * Make sure NMIs see reseted values.
+	 */
+	barrier();
+	trace_osnoise_callback_enabled = true;
+
+	retval = start_per_cpu_kthreads(tr);
+	if (retval) {
+		unhook_irq_events();
+		return retval;
+	}
+
+	osnoise_busy = true;
+
+	return 0;
+}
+
+static void osnoise_tracer_start(struct trace_array *tr)
+{
+	int retval;
+
+	if (osnoise_busy)
+		return;
+
+	retval = __osnoise_tracer_start(tr);
+	if (retval)
+		pr_err(BANNER "Error starting osnoise tracer\n");
+
+}
+
+static void osnoise_tracer_stop(struct trace_array *tr)
+{
+	if (!osnoise_busy)
+		return;
+
+	trace_osnoise_callback_enabled = false;
+	barrier();
+
+	stop_per_cpu_kthreads();
+
+	unhook_irq_events();
+	unhook_softirq_events();
+	unhook_thread_events();
+
+	osnoise_busy = false;
+}
+
+static int osnoise_tracer_init(struct trace_array *tr)
+{
+
+	/* Only allow one instance to enable this */
+	if (osnoise_busy)
+		return -EBUSY;
+
+	osnoise_trace = tr;
+	tr->max_latency = 0;
+
+	osnoise_tracer_start(tr);
+
+	return 0;
+}
+
+static void osnoise_tracer_reset(struct trace_array *tr)
+{
+	osnoise_tracer_stop(tr);
+}
+
+static struct tracer osnoise_tracer __read_mostly = {
+	.name		= "osnoise",
+	.init		= osnoise_tracer_init,
+	.reset		= osnoise_tracer_reset,
+	.start		= osnoise_tracer_start,
+	.stop		= osnoise_tracer_stop,
+	.print_header	= print_osnoise_headers,
+	.allow_instances = true,
+};
+
+#ifdef CONFIG_TIMERLAT_TRACER
+static void timerlat_tracer_start(struct trace_array *tr)
+{
+	int retval;
+
+	if (osnoise_busy)
+		return;
+
+	osnoise_data.timerlat_tracer = 1;
+
+	retval = __osnoise_tracer_start(tr);
+	if (retval)
+		goto out_err;
+
+	return;
+out_err:
+	pr_err(BANNER "Error starting timerlat tracer\n");
+}
+
+static void timerlat_tracer_stop(struct trace_array *tr)
+{
+	int cpu;
+
+	if (!osnoise_busy)
+		return;
+
+	for_each_online_cpu(cpu)
+		per_cpu(per_cpu_osnoise_var, cpu).sampling = 0;
+
+	osnoise_tracer_stop(tr);
+
+	osnoise_data.timerlat_tracer = 0;
+}
+
+static int timerlat_tracer_init(struct trace_array *tr)
+{
+	/* Only allow one instance to enable this */
+	if (osnoise_busy)
+		return -EBUSY;
+
+	osnoise_trace = tr;
+
+	tr->max_latency = 0;
+
+	timerlat_tracer_start(tr);
+
+	return 0;
+}
+
+static void timerlat_tracer_reset(struct trace_array *tr)
+{
+	timerlat_tracer_stop(tr);
+}
+
+static struct tracer timerlat_tracer __read_mostly = {
+	.name		= "timerlat",
+	.init		= timerlat_tracer_init,
+	.reset		= timerlat_tracer_reset,
+	.start		= timerlat_tracer_start,
+	.stop		= timerlat_tracer_stop,
+	.print_header	= print_timerlat_headers,
+	.allow_instances = true,
+};
+#endif /* CONFIG_TIMERLAT_TRACER */
+
+__init static int init_osnoise_tracer(void)
+{
+	int ret;
+
+	mutex_init(&interface_lock);
+
+	cpumask_copy(&osnoise_cpumask, cpu_all_mask);
+
+	ret = register_tracer(&osnoise_tracer);
+	if (ret) {
+		pr_err(BANNER "Error registering osnoise!\n");
+		return ret;
+	}
+
+#ifdef CONFIG_TIMERLAT_TRACER
+	ret = register_tracer(&timerlat_tracer);
+	if (ret) {
+		pr_err(BANNER "Error registering timerlat\n");
+		return ret;
+	}
+#endif
+	osnoise_init_hotplug_support();
+
+	init_tracefs();
+
+	return 0;
+}
+late_initcall(init_osnoise_tracer);

kernel/trace/trace_output.c

···
 	return trace_handle_return(s);
 }
 
-
 static enum print_line_t
 trace_hwlat_raw(struct trace_iterator *iter, int flags,
 		struct trace_event *event)
···
 static struct trace_event trace_hwlat_event = {
 	.type		= TRACE_HWLAT,
 	.funcs		= &trace_hwlat_funcs,
+};
+
+/* TRACE_OSNOISE */
+static enum print_line_t
+trace_osnoise_print(struct trace_iterator *iter, int flags,
+		    struct trace_event *event)
+{
+	struct trace_entry *entry = iter->ent;
+	struct trace_seq *s = &iter->seq;
+	struct osnoise_entry *field;
+	u64 ratio, ratio_dec;
+	u64 net_runtime;
+
+	trace_assign_type(field, entry);
+
+	/*
+	 * compute the available % of cpu time.
+	 */
+	net_runtime = field->runtime - field->noise;
+	ratio = net_runtime * 10000000;
+	do_div(ratio, field->runtime);
+	ratio_dec = do_div(ratio, 100000);
+
+	trace_seq_printf(s, "%llu %10llu %3llu.%05llu %7llu",
+			 field->runtime,
+			 field->noise,
+			 ratio, ratio_dec,
+			 field->max_sample);
+
+	trace_seq_printf(s, " %6u", field->hw_count);
+	trace_seq_printf(s, " %6u", field->nmi_count);
+	trace_seq_printf(s, " %6u", field->irq_count);
+	trace_seq_printf(s, " %6u", field->softirq_count);
+	trace_seq_printf(s, " %6u", field->thread_count);
+
+	trace_seq_putc(s, '\n');
+
+	return trace_handle_return(s);
+}
+
+static enum print_line_t
+trace_osnoise_raw(struct trace_iterator *iter, int flags,
+		  struct trace_event *event)
+{
+	struct osnoise_entry *field;
+	struct trace_seq *s = &iter->seq;
+
+	trace_assign_type(field, iter->ent);
+
+	trace_seq_printf(s, "%lld %llu %llu %u %u %u %u %u\n",
+			 field->runtime,
+			 field->noise,
+			 field->max_sample,
+			 field->hw_count,
+			 field->nmi_count,
+			 field->irq_count,
+			 field->softirq_count,
+			 field->thread_count);
+
+	return trace_handle_return(s);
+}
+
+static struct trace_event_functions trace_osnoise_funcs = {
+	.trace		= trace_osnoise_print,
+	.raw		= trace_osnoise_raw,
+};
+
+static struct trace_event trace_osnoise_event = {
+	.type		= TRACE_OSNOISE,
+	.funcs		= &trace_osnoise_funcs,
+};
+
+/* TRACE_TIMERLAT */
+static enum print_line_t
+trace_timerlat_print(struct trace_iterator *iter, int flags,
+		     struct trace_event *event)
+{
+	struct trace_entry *entry = iter->ent;
+	struct trace_seq *s = &iter->seq;
+	struct timerlat_entry *field;
+
+	trace_assign_type(field, entry);
+
+	trace_seq_printf(s, "#%-5u context %6s timer_latency %9llu ns\n",
+			 field->seqnum,
+			 field->context ? "thread" : "irq",
+			 field->timer_latency);
+
+	return trace_handle_return(s);
+}
+
+static enum print_line_t
+trace_timerlat_raw(struct trace_iterator *iter, int flags,
+		   struct trace_event *event)
+{
+	struct timerlat_entry *field;
+	struct trace_seq *s = &iter->seq;
+
+	trace_assign_type(field, iter->ent);
+
+	trace_seq_printf(s, "%u %d %llu\n",
+			 field->seqnum,
+			 field->context,
+			 field->timer_latency);
+
+	return trace_handle_return(s);
+}
+
+static struct trace_event_functions trace_timerlat_funcs = {
+	.trace		= trace_timerlat_print,
+	.raw		= trace_timerlat_raw,
+};
+
+static struct trace_event trace_timerlat_event = {
+	.type		= TRACE_TIMERLAT,
+	.funcs		= &trace_timerlat_funcs,
 };
 
 /* TRACE_BPUTS */
···
 	&trace_bprint_event,
 	&trace_print_event,
 	&trace_hwlat_event,
+	&trace_osnoise_event,
+	&trace_timerlat_event,
 	&trace_raw_data_event,
 	&trace_func_repeats_event,
 	NULL

kernel/trace/trace_sched_wakeup.c

···
 static int			wakeup_cpu;
 static int			wakeup_current_cpu;
 static unsigned			wakeup_prio = -1;
-static int			wakeup_rt;
-static int			wakeup_dl;
-static int			tracing_dl = 0;
+static bool			wakeup_rt;
+static bool			wakeup_dl;
+static bool			tracing_dl;
 
 static arch_spinlock_t wakeup_lock =
 	(arch_spinlock_t)__ARCH_SPIN_LOCK_UNLOCKED;
···
 {
 	wakeup_cpu = -1;
 	wakeup_prio = -1;
-	tracing_dl = 0;
+	tracing_dl = false;
 
 	if (wakeup_task)
 		put_task_struct(wakeup_task);
···
 	 * another task until the first one wakes up.
 	 */
 	if (dl_task(p))
-		tracing_dl = 1;
+		tracing_dl = true;
 	else
-		tracing_dl = 0;
+		tracing_dl = false;
 
 	wakeup_task = get_task_struct(p);
 
···
 	if (wakeup_busy)
 		return -EBUSY;
 
-	wakeup_dl = 0;
-	wakeup_rt = 0;
+	wakeup_dl = false;
+	wakeup_rt = false;
 	return __wakeup_tracer_init(tr);
 }
 
···
 	if (wakeup_busy)
 		return -EBUSY;
 
-	wakeup_dl = 0;
-	wakeup_rt = 1;
+	wakeup_dl = false;
+	wakeup_rt = true;
 	return __wakeup_tracer_init(tr);
 }
 
···
 	if (wakeup_busy)
 		return -EBUSY;
 
-	wakeup_dl = 1;
-	wakeup_rt = 0;
+	wakeup_dl = true;
+	wakeup_rt = false;
 	return __wakeup_tracer_init(tr);
 }
 

kernel/tracepoint.c

···
  * Add the probe function to a tracepoint.
  */
 static int tracepoint_add_func(struct tracepoint *tp,
-			       struct tracepoint_func *func, int prio)
+			       struct tracepoint_func *func, int prio,
+			       bool warn)
 {
 	struct tracepoint_func *old, *tp_funcs;
 	int ret;
···
 			lockdep_is_held(&tracepoints_mutex));
 	old = func_add(&tp_funcs, func, prio);
 	if (IS_ERR(old)) {
-		WARN_ON_ONCE(PTR_ERR(old) != -ENOMEM);
+		WARN_ON_ONCE(warn && PTR_ERR(old) != -ENOMEM);
 		return PTR_ERR(old);
 	}
 
···
 }
 
 /**
+ * tracepoint_probe_register_prio_may_exist -  Connect a probe to a tracepoint with priority
+ * @tp: tracepoint
+ * @probe: probe handler
+ * @data: tracepoint data
+ * @prio: priority of this function over other registered functions
+ *
+ * Same as tracepoint_probe_register_prio() except that it will not warn
+ * if the tracepoint is already registered.
+ */
+int tracepoint_probe_register_prio_may_exist(struct tracepoint *tp, void *probe,
+					     void *data, int prio)
+{
+	struct tracepoint_func tp_func;
+	int ret;
+
+	mutex_lock(&tracepoints_mutex);
+	tp_func.func = probe;
+	tp_func.data = data;
+	tp_func.prio = prio;
+	ret = tracepoint_add_func(tp, &tp_func, prio, false);
+	mutex_unlock(&tracepoints_mutex);
+	return ret;
+}
+EXPORT_SYMBOL_GPL(tracepoint_probe_register_prio_may_exist);
+
+/**
  * tracepoint_probe_register_prio -  Connect a probe to a tracepoint with priority
  * @tp: tracepoint
  * @probe: probe handler
···
 	tp_func.func = probe;
 	tp_func.data = data;
 	tp_func.prio = prio;
-	ret = tracepoint_add_func(tp, &tp_func, prio);
+	ret = tracepoint_add_func(tp, &tp_func, prio, true);
 	mutex_unlock(&tracepoints_mutex);
 	return ret;
 }

lib/bootconfig.c

···
 	struct xbc_node *node;
 
 	if (parent)
-		node = xbc_node_get_child(parent);
+		node = xbc_node_get_subkey(parent);
 	else
 		node = xbc_root_node();
 
···
 		if (!xbc_node_match_prefix(node, &key))
 			node = xbc_node_get_next(node);
 		else if (*key != '\0')
-			node = xbc_node_get_child(node);
+			node = xbc_node_get_subkey(node);
 		else
 			break;
 	}
···
 struct xbc_node * __init xbc_node_find_next_leaf(struct xbc_node *root,
 						 struct xbc_node *node)
 {
+	struct xbc_node *next;
+
 	if (unlikely(!xbc_data))
 		return NULL;
 
···
 		if (!node)
 			node = xbc_nodes;
 	} else {
+		/* Leaf node may have a subkey */
+		next = xbc_node_get_subkey(node);
+		if (next) {
+			node = next;
+			goto found;
+		}
+
 		if (node == root)	/* @root was a leaf, no child node. */
 			return NULL;
 
···
 		node = xbc_node_get_next(node);
 	}
 
+found:
 	while (node && !xbc_node_is_leaf(node))
 		node = xbc_node_get_child(node);
 
···
 	return node;
 }
 
-static struct xbc_node * __init xbc_add_sibling(char *data, u32 flag)
+static inline __init struct xbc_node *xbc_last_child(struct xbc_node *node)
+{
+	while (node->child)
+		node = xbc_node_get_child(node);
+
+	return node;
+}
+
+static struct xbc_node * __init __xbc_add_sibling(char *data, u32 flag, bool head)
 {
 	struct xbc_node *sib, *node = xbc_add_node(data, flag);
 
 	if (node) {
 		if (!last_parent) {
+			/* Ignore @head in this case */
 			node->parent = XBC_NODE_MAX;
 			sib = xbc_last_sibling(xbc_nodes);
 			sib->next = xbc_node_index(node);
 		} else {
 			node->parent = xbc_node_index(last_parent);
-			if (!last_parent->child) {
+			if (!last_parent->child || head) {
+				node->next = last_parent->child;
 				last_parent->child = xbc_node_index(node);
 			} else {
 				sib = xbc_node_get_child(last_parent);
···
 		xbc_parse_error("Too many nodes", data);
 
 	return node;
+}
+
+static inline struct xbc_node * __init xbc_add_sibling(char *data, u32 flag)
+{
+	return __xbc_add_sibling(data, flag, false);
+}
+
+static inline struct xbc_node * __init xbc_add_head_sibling(char *data, u32 flag)
+{
+	return __xbc_add_sibling(data, flag, true);
 }
 
 static inline __init struct xbc_node *xbc_add_child(char *data, u32 flag)
···
 	char *next;
 	int c = 0;
 
+	if (last_parent->child)
+		last_parent = xbc_node_get_child(last_parent);
+
 	do {
 		c = __xbc_parse_value(__v, &next);
 		if (c < 0)
 			return c;
 
-		node = xbc_add_sibling(*__v, XBC_VALUE);
+		node = xbc_add_child(*__v, XBC_VALUE);
 		if (!node)
 			return -ENOMEM;
 		*__v = next;
 	} while (c == ',');
-	node->next = 0;
+	node->child = 0;
 
 	return c;
 }
···
 		node = find_match_node(xbc_nodes, k);
 	else {
 		child = xbc_node_get_child(last_parent);
+		/* Since the value node is the first child, skip it. */
 		if (child && xbc_node_is_value(child))
-			return xbc_parse_error("Subkey is mixed with value", k);
+			child = xbc_node_get_next(child);
 		node = find_match_node(child, k);
 	}
 
···
 	if (ret)
 		return ret;
 
-	child = xbc_node_get_child(last_parent);
-	if (child) {
-		if (xbc_node_is_key(child))
-			return xbc_parse_error("Value is mixed with subkey", v);
-		else if (op == '=')
-			return xbc_parse_error("Value is redefined", v);
-	}
-
 	c = __xbc_parse_value(&v, &next);
 	if (c < 0)
 		return c;
 
-	if (op == ':' && child) {
-		xbc_init_node(child, v, XBC_VALUE);
-	} else if (!xbc_add_sibling(v, XBC_VALUE))
+	child = xbc_node_get_child(last_parent);
+	if (child && xbc_node_is_value(child)) {
+		if (op == '=')
+			return xbc_parse_error("Value is redefined", v);
+		if (op == ':') {
+			unsigned short nidx = child->next;
+
+			xbc_init_node(child, v, XBC_VALUE);
+			child->next = nidx;	/* keep subkeys */
+			goto array;
+		}
+		/* op must be '+' */
+		last_parent = xbc_last_child(child);
+	}
+	/* The value node should always be the first child */
+	if (!xbc_add_head_sibling(v, XBC_VALUE))
 		return -ENOMEM;
 
+array:
 	if (c == ',') {	/* Array */
 		c = xbc_parse_array(&next);
 		if (c < 0)

lib/seq_buf.c

···
 
 	WARN_ON(s->size == 0);
 
+	BUILD_BUG_ON(MAX_MEMHEX_BYTES * 2 >= HEX_CHARS);
+
 	while (len) {
-		start_len = min(len, HEX_CHARS - 1);
+		start_len = min(len, MAX_MEMHEX_BYTES);
 #ifdef __BIG_ENDIAN
 		for (i = 0, j = 0; i < start_len; i++) {
 #else
···
 			break;
 
 		/* j increments twice per loop */
-		len -= j / 2;
 		hex[j++] = ' ';
 
 		seq_buf_putmem(s, hex, j);
 		if (seq_buf_has_overflowed(s))
 			return -1;
+
+		len -= start_len;
+		data += start_len;
 	}
 	return 0;
 }

tools/bootconfig/main.c

···
 			q = '\'';
 		else
 			q = '"';
-		printf("%c%s%c%s", q, val, q, node->next ? ", " : eol);
+		printf("%c%s%c%s", q, val, q, xbc_node_is_array(node) ? ", " : eol);
 		i++;
 	}
 	return i;
···
 
 static void xbc_show_compact_tree(void)
 {
-	struct xbc_node *node, *cnode;
+	struct xbc_node *node, *cnode = NULL, *vnode;
 	int depth = 0, i;
 
 	node = xbc_root_node();
 	while (node && xbc_node_is_key(node)) {
 		for (i = 0; i < depth; i++)
 			printf("\t");
-		cnode = xbc_node_get_child(node);
+		if (!cnode)
+			cnode = xbc_node_get_child(node);
 		while (cnode && xbc_node_is_key(cnode) && !cnode->next) {
+			vnode = xbc_node_get_child(cnode);
+			/*
+			 * If @cnode has value and subkeys, this
+			 * should show it as below.
+			 *
+			 * key(@node) {
+			 *      key(@cnode) = value;
+			 *      key(@cnode) {
+			 *          subkeys;
+			 *      }
+			 * }
+			 */
+			if (vnode && xbc_node_is_value(vnode) && vnode->next)
+				break;
 			printf("%s.", xbc_node_get_data(node));
 			node = cnode;
-			cnode = xbc_node_get_child(node);
+			cnode = vnode;
 		}
 		if (cnode && xbc_node_is_key(cnode)) {
 			printf("%s {\n", xbc_node_get_data(node));
 			depth++;
 			node = cnode;
+			cnode = NULL;
 			continue;
 		} else if (cnode && xbc_node_is_value(cnode)) {
 			printf("%s = ", xbc_node_get_data(node));
 			xbc_show_value(cnode, true);
+			/*
+			 * If @node has value and subkeys, continue
+			 * looping on subkeys with same node.
+			 */
+			if (cnode->next) {
+				cnode = xbc_node_get_next(cnode);
+				continue;
+			}
 		} else {
 			printf("%s;\n", xbc_node_get_data(node));
 		}
+		cnode = NULL;
 
 		if (node->next) {
 			node = xbc_node_get_next(node);
···
 				return;
 			if (!xbc_node_get_child(node)->next)
 				continue;
-			depth--;
-			for (i = 0; i < depth; i++)
-				printf("\t");
-			printf("}\n");
+			if (depth) {
+				depth--;
+				for (i = 0; i < depth; i++)
+					printf("\t");
+				printf("}\n");
+			}
 		}
 		node = xbc_node_get_next(node);
 	}
···
 	char key[XBC_KEYLEN_MAX];
 	struct xbc_node *leaf;
 	const char *val;
-	int ret = 0;
 
 	xbc_for_each_key_value(leaf, val) {
-		ret = xbc_node_compose_key(leaf, key, XBC_KEYLEN_MAX);
-		if (ret < 0)
+		if (xbc_node_compose_key(leaf, key, XBC_KEYLEN_MAX) < 0) {
+			fprintf(stderr, "Failed to compose key %d\n", ret);
 			break;
+		}
 		printf("%s = ", key);
 		if (!val || val[0] == '\0') {
 			printf("\"\"\n");
···
 		}
 		xbc_show_value(xbc_node_get_child(leaf), false);
 	}
-}
-
-/* Simple real checksum */
-static int checksum(unsigned char *buf, int len)
-{
-	int i, sum = 0;
-
-	for (i = 0; i < len; i++)
-		sum += buf[i];
-
-	return sum;
 }
 
 #define PAGE_SIZE	4096
···
 		return ret;
 
 	/* Wrong Checksum */
-	rcsum = checksum((unsigned char *)*buf, size);
+	rcsum = xbc_calc_checksum(*buf, size);
 	if (csum != rcsum) {
 		pr_err("checksum error: %d != %d\n", csum, rcsum);
 		return -EINVAL;
···
 		return ret;
 	}
 	size = strlen(buf) + 1;
-	csum = checksum((unsigned char *)buf, size);
+	csum = xbc_calc_checksum(buf, size);
 
 	/* Backup the bootconfig data */
 	data = calloc(size + BOOTCONFIG_ALIGN +

tools/bootconfig/samples/bad-override.bconf

···
-key.subkey = value
-# We can not override pre-defined subkeys with value
-key := value

tools/bootconfig/samples/bad-override2.bconf

···
-key = value
-# We can not override pre-defined value with subkey
-key.subkey := value

tools/bootconfig/samples/good-mixed-append.bconf

···
+key = foo
+keyx.subkey = value
+key += bar
+

tools/bootconfig/samples/good-mixed-kv3.bconf

···
+# mixed key and subkeys with braces
+key = value
+key {
+	subkey1
+	subkey2 = foo
+}

tools/bootconfig/samples/good-mixed-override.bconf

···
+key.foo = bar
+key = value
+# mixed key value can be overridden
+key := value2

tools/testing/ktest/examples/bootconfigs/boottrace.bconf

···
+ftrace.event {
+	task.task_newtask {
+		filter = "pid < 128"
+		enable
+	}
+	kprobes.vfs_read {
+		probes = "vfs_read $arg1 $arg2"
+		filter = "common_pid < 200"
+		enable
+	}
+	synthetic.initcall_latency {
+		fields = "unsigned long func", "u64 lat"
+		actions = "hist:keys=func.sym,lat:vals=lat:sort=lat"
+	}
+	initcall.initcall_start {
+		actions = "hist:keys=func:ts0=common_timestamp.usecs"
+	}
+	initcall.initcall_finish {
+		actions = "hist:keys=func:lat=common_timestamp.usecs-$ts0:onmatch(initcall.initcall_start).initcall_latency(func,$lat)"
+	}
+}
+
+ftrace.instance {
+	foo {
+		tracer = "function"
+		ftrace.filters = "user_*"
+		cpumask = 1
+		options = nosym-addr
+		buffer_size = 512KB
+		trace_clock = mono
+		event.signal.signal_deliver.actions=snapshot
+	}
+	bar {
+		tracer = "function"
+		ftrace.filters = "kernel_*"
+		cpumask = 2
+		trace_clock = x86-tsc
+	}
+}
+
+ftrace.alloc_snapshot
+
+kernel {
+	trace_options = sym-addr
+	trace_event = "initcall:*"
+	trace_buf_size = 1M
+	ftrace = function
+	ftrace_filter = "vfs*"
+}

tools/testing/ktest/examples/bootconfigs/config-bootconfig

···
+CONFIG_CMDLINE="bootconfig"

tools/testing/ktest/examples/bootconfigs/functiongraph.bconf

···
+ftrace {
+	tracing_on = 0  # off by default
+	tracer = function_graph
+	event.kprobes {
+		start_event {
+			probes = "pci_proc_init"
+			actions = "traceon"
+		}
+		end_event {
+			probes = "pci_proc_init%return"
+			actions = "traceoff"
+		}
+	}
+}
+

tools/testing/ktest/examples/bootconfigs/tracing.bconf

···
+ftrace {
+	tracer = function_graph;
+	options = event-fork, sym-addr, stacktrace;
+	buffer_size = 1M;
+	alloc_snapshot;
+	trace_clock = global;
+	events = "task:task_newtask", "initcall:*";
+	event.sched.sched_process_exec {
+		filter = "pid < 128";
+	}
+	instance.bar {
+		event.kprobes {
+			myevent {
+				probes = "vfs_read $arg2 $arg3";
+			}
+			myevent2 {
+				probes = "vfs_write $arg2 +0($arg2):ustring $arg3";
+			}
+			myevent3 {
+				probes = "initrd_load";
+			}
+			enable
+		}
+	}
+	instance.foo {
+		tracer = function;
+		tracing_on = false;
+	};
+}
+kernel {
+	ftrace_dump_on_oops = "orig_cpu"
+	traceoff_on_warning
+}

tools/testing/ktest/examples/bootconfigs/verify-boottrace.sh

···
+#!/bin/sh
+
+cd /sys/kernel/tracing
+
+compare_file() {
+	file="$1"
+	val="$2"
+	content=`cat $file`
+	if [ "$content" != "$val" ]; then
+		echo "FAILED: $file has '$content', expected '$val'"
+		exit 1
+	fi
+}
+
+compare_file_partial() {
+	file="$1"
+	val="$2"
+	content=`cat $file | sed -ne "/^$val/p"`
+	if [ -z "$content" ]; then
+		echo "FAILED: $file does not contain '$val'"
+		cat $file
+		exit 1
+	fi
+}
+
+file_contains() {
+	file=$1
+	val="$2"
+
+	if ! grep -q "$val" $file ; then
+		echo "FAILED: $file does not contain $val"
+		cat $file
+		exit 1
+	fi
+}
+
+compare_mask() {
+	file=$1
+	val="$2"
+
+	content=`cat $file | sed -ne "/^[0 ]*$val/p"`
+	if [ -z "$content" ]; then
+		echo "FAILED: $file does not have mask '$val'"
+		cat $file
+		exit 1
+	fi
+}
+
+compare_file "events/task/task_newtask/filter" "pid < 128"
+compare_file "events/task/task_newtask/enable" "1"
+
+compare_file "events/kprobes/vfs_read/filter" "common_pid < 200"
+compare_file "events/kprobes/vfs_read/enable" "1"
+
+compare_file_partial "events/synthetic/initcall_latency/trigger" "hist:keys=func.sym,lat:vals=hitcount,lat:sort=lat"
+compare_file_partial "events/synthetic/initcall_latency/enable" "0"
+
+compare_file_partial "events/initcall/initcall_start/trigger" "hist:keys=func:vals=hitcount:ts0=common_timestamp.usecs"
+compare_file_partial "events/initcall/initcall_start/enable" "1"
+
+compare_file_partial "events/initcall/initcall_finish/trigger" 'hist:keys=func:vals=hitcount:lat=common_timestamp.usecs-\$ts0:sort=hitcount:size=2048:clock=global:onmatch(initcall.initcall_start).initcall_latency(func,\$lat)'
+compare_file_partial "events/initcall/initcall_finish/enable" "1"
+
+compare_file "instances/foo/current_tracer" "function"
+file_contains "instances/foo/set_ftrace_filter" "^user"
+compare_file "instances/foo/buffer_size_kb" "512"
+compare_mask "instances/foo/tracing_cpumask" "1"
+compare_file "instances/foo/options/sym-addr" "0"
+file_contains "instances/foo/trace_clock" '\[mono\]'
+compare_file_partial "instances/foo/events/signal/signal_deliver/trigger" "snapshot"
+
+compare_file "instances/bar/current_tracer" "function"
+file_contains "instances/bar/set_ftrace_filter" "^kernel"
+compare_mask "instances/bar/tracing_cpumask" "2"
+file_contains "instances/bar/trace_clock" '\[x86-tsc\]'
+
+file_contains "snapshot" "Snapshot is allocated"
+compare_file "options/sym-addr" "1"
+compare_file "events/initcall/enable" "1"
+compare_file "buffer_size_kb" "1027"
+compare_file "current_tracer" "function"
+file_contains "set_ftrace_filter" '^vfs'
+
+exit 0

tools/testing/ktest/examples/bootconfigs/verify-functiongraph.sh

···
+#!/bin/sh
+
+cd /sys/kernel/tracing
+
+compare_file() {
+	file="$1"
+	val="$2"
+	content=`cat $file`
+	if [ "$content" != "$val" ]; then
+		echo "FAILED: $file has '$content', expected '$val'"
+		exit 1
+	fi
+}
+
+compare_file_partial() {
+	file="$1"
+	val="$2"
+	content=`cat $file | sed -ne "/^$val/p"`
+	if [ -z "$content" ]; then
+		echo "FAILED: $file does not contain '$val'"
+		cat $file
+		exit 1
+	fi
+}
+
+file_contains() {
+	file=$1
+	val="$2"
+
+	if ! grep -q "$val" $file ; then
+		echo "FAILED: $file does not contain $val"
+		cat $file
+		exit 1
+	fi
+}
+
+compare_mask() {
+	file=$1
+	val="$2"
+
+	content=`cat $file | sed -ne "/^[0 ]*$val/p"`
+	if [ -z "$content" ]; then
+		echo "FAILED: $file does not have mask '$val'"
+		cat $file
+		exit 1
+	fi
+}
+
+
+compare_file "tracing_on" "0"
+compare_file "current_tracer" "function_graph"
+
+compare_file_partial "events/kprobes/start_event/enable" "1"
+compare_file_partial "events/kprobes/start_event/trigger" "traceon"
+file_contains "kprobe_events" 'start_event.*pci_proc_init'
+
+compare_file_partial "events/kprobes/end_event/enable" "1"
+compare_file_partial "events/kprobes/end_event/trigger" "traceoff"
+file_contains "kprobe_events" '^r.*end_event.*pci_proc_init'
+
+exit 0

tools/testing/ktest/examples/bootconfigs/verify-tracing.sh

···
+#!/bin/sh
+
+cd /sys/kernel/tracing
+
+compare_file() {
+	file="$1"
+	val="$2"
+	content=`cat $file`
+	if [ "$content" != "$val" ]; then
+		echo "FAILED: $file has '$content', expected '$val'"
+		exit 1
+	fi
+}
+
+compare_file_partial() {
+	file="$1"
+	val="$2"
+	content=`cat $file | sed -ne "/^$val/p"`
+	if [ -z "$content" ]; then
+		echo "FAILED: $file does not contain '$val'"
+		cat $file
+		exit 1
+	fi
+}
+
+file_contains() {
+	file=$1
+	val="$2"
+
+	if ! grep -q "$val" $file ; then
+		echo "FAILED: $file does not contain $val"
+		cat $file
+		exit 1
+	fi
+}
+
+compare_mask() {
+	file=$1
+	val="$2"
+
+	content=`cat $file | sed -ne "/^[0 ]*$val/p"`
+	if [ -z "$content" ]; then
+		echo "FAILED: $file does not have mask '$val'"
+		cat $file
+		exit 1
+	fi
+}
+
+compare_file "current_tracer" "function_graph"
+compare_file "options/event-fork" "1"
+compare_file "options/sym-addr" "1"
+compare_file "options/stacktrace" "1"
+compare_file "buffer_size_kb" "1024"
+file_contains "snapshot" "Snapshot is allocated"
+file_contains "trace_clock" '\[global\]'
+
+compare_file "events/initcall/enable" "1"
+compare_file "events/task/task_newtask/enable" "1"
+compare_file "events/sched/sched_process_exec/filter" "pid < 128"
+compare_file "events/kprobes/enable" "1"
+
+compare_file "instances/bar/events/kprobes/myevent/enable" "1"
+compare_file "instances/bar/events/kprobes/myevent2/enable" "1"
+compare_file "instances/bar/events/kprobes/myevent3/enable" "1"
+
+compare_file "instances/foo/current_tracer" "function"
+compare_file "instances/foo/tracing_on" "0"
+
+compare_file "/proc/sys/kernel/ftrace_dump_on_oops" "2"
+compare_file "/proc/sys/kernel/traceoff_on_warning" "1"
+
+exit 0

tools/testing/ktest/examples/include/bootconfig.conf

···
+# bootconfig.conf
+#
+# Tests to test some bootconfig scripts
+
+# List where on the target machine the initrd is used
+INITRD := /boot/initramfs-test.img
+
+# Install bootconfig on the target machine and define the path here.
+BOOTCONFIG := /usr/bin/bootconfig
+
+# Currenty we just build the .config in the BUILD_DIR
+BUILD_TYPE := oldconfig
+
+# Helper macro to run bootconfig on the target
+# SSH is defined in include/defaults.conf
+ADD_BOOTCONFIG := ${SSH} "${BOOTCONFIG} -d ${INITRD} && ${BOOTCONFIG} -a /tmp/${BOOTCONFIG_FILE} ${INITRD}"
+
+# This copies a bootconfig script to the target and then will
+# add it to the initrd. SSH_USER is defined in include/defaults.conf
+# and MACHINE is defined in the example configs.
+BOOTCONFIG_TEST_PREP = scp ${BOOTCONFIG_PATH}${BOOTCONFIG_FILE} ${SSH_USER}@${MACHINE}:/tmp && ${ADD_BOOTCONFIG}
+
+# When a test is complete, remove the bootconfig from the initrd.
+CLEAR_BOOTCONFIG := ${SSH} "${BOOTCONFIG} -d ${INITRD}"
+
+# Run a verifier on the target after it had booted, to make sure that the
+# bootconfig script did what it was expected to do
+DO_TEST = scp ${BOOTCONFIG_PATH}${BOOTCONFIG_VERIFY} ${SSH_USER}@${MACHINE}:/tmp && ${SSH} /tmp/${BOOTCONFIG_VERIFY}
+
+# Comment this out to not run the boot configs
+RUN_BOOTCONFIG := 1
+
+TEST_START IF DEFINED RUN_BOOTCONFIG
+TEST_TYPE = test
+TEST_NAME = bootconfig boottrace
+# Just testing the bootconfig on initrd, no need to build the kernel
+BUILD_TYPE = nobuild
+BOOTCONFIG_FILE = boottrace.bconf
+BOOTCONFIG_VERIFY = verify-boottrace.sh
+ADD_CONFIG = ${ADD_CONFIG} ${BOOTCONFIG_PATH}/config-bootconfig
+PRE_TEST = ${BOOTCONFIG_TEST_PREP}
+PRE_TEST_DIE = 1
+TEST = ${DO_TEST}
+POST_TEST = ${CLEAR_BOOTCONFIG}
+
+TEST_START IF DEFINED RUN_BOOTCONFIG
+TEST_TYPE = test
+TEST_NAME = bootconfig function graph
+BUILD_TYPE = nobuild
+BOOTCONFIG_FILE = functiongraph.bconf
+BOOTCONFIG_VERIFY = verify-functiongraph.sh
+ADD_CONFIG = ${ADD_CONFIG} ${BOOTCONFIG_PATH}/config-bootconfig
+PRE_TEST = ${BOOTCONFIG_TEST_PREP}
+PRE_TEST_DIE = 1
+TEST = ${DO_TEST}
+POST_TEST = ${CLEAR_BOOTCONFIG}
+
+TEST_START IF DEFINED RUN_BOOTCONFIG
+TEST_TYPE = test
+TEST_NAME = bootconfig tracing
+BUILD_TYPE = nobuild
+BOOTCONFIG_FILE = tracing.bconf
+BOOTCONFIG_VERIFY = verify-tracing.sh
+ADD_CONFIG = ${ADD_CONFIG} ${BOOTCONFIG_PATH}/config-bootconfig
+PRE_TEST = ${BOOTCONFIG_TEST_PREP}
+PRE_TEST_DIE = 1
+TEST = ${DO_TEST}
+POST_TEST = ${CLEAR_BOOTCONFIG}
+

tools/testing/ktest/examples/kvm.conf

···
 INCLUDE include/tests.conf
 INCLUDE include/bisect.conf
 INCLUDE include/min-config.conf
+INCLUDE include/bootconfig.conf