Linux kernel ============ This file was moved to Documentation/admin-guide/README.rst Please notice that there are several guides for kernel developers and users. These guides can be rendered in a number of formats, like HTML and PDF. In order to build the documentation, use ``make htmldocs`` or ``make pdfdocs``. There are various text files in the Documentation/ subdirectory, several of them using the Restructured Text markup notation. See Documentation/00-INDEX for a list of what is contained in each file. Please read the Documentation/process/changes.rst file, as it contains the requirements for building and running the kernel, and information about the problems which may result by upgrading your kernel.
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Pull MIPS fixes from Ralf Baechle:
"The two indirect syscall fixes have sat in linux-next for a few days.
I did check back with a hardware designer to ensure a SYNC is really
what's required for the GIC fix and so the GIC fix didn't make it into
to linux-next in time for this final pull request.
It builds in local build tests and passes Imagination's test system"
* 'upstream' of git://git.linux-mips.org/pub/scm/ralf/upstream-linus:
irqchip: mips-gic: SYNC after enabling GIC region
MIPS: Remove pt_regs adjustments in indirect syscall handler
MIPS: seccomp: Fix indirect syscall args
Pull x86 fixes from Thomas Gleixner:
- Expand the space for uncompressing as the LZ4 worst case does not fit
into the currently reserved space
- Validate boot parameters more strictly to prevent out of bound access
in the decompressor/boot code
- Fix off by one errors in get_segment_base()
* 'x86-urgent-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip:
x86/boot: Prevent faulty bootparams.screeninfo from causing harm
x86/boot: Provide more slack space during decompression
x86/ldt: Fix off by one in get_segment_base()
A SYNC is required between enabling the GIC region and actually trying
to use it, even if the first access is a read, otherwise its possible
depending on the timing (and in my case depending on the precise
alignment of certain kernel code) to hit CM bus errors on that first
access.
Add the SYNC straight after setting the GIC base.
[paul.burton@imgtec.com:
Changes later in this series increase our likelihood of hitting this
by reducing the amount of code that runs between enabling the GIC &
accessing it.]
Fixes: a7057270c280 ("irqchip: mips-gic: Add device-tree support")
Signed-off-by: James Hogan <james.hogan@imgtec.com>
Signed-off-by: Paul Burton <paul.burton@imgtec.com>
Acked-by: Marc Zyngier <marc.zyngier@arm.com>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Jason Cooper <jason@lakedaemon.net>
Cc: James Hogan <james.hogan@imgtec.com>
Cc: linux-kernel@vger.kernel.org
Cc: linux-mips@linux-mips.org
Cc: <stable@vger.kernel.org> # 3.19.x-
Patchwork: https://patchwork.linux-mips.org/patch/17019/
Signed-off-by: Ralf Baechle <ralf@linux-mips.org>
Pull timer fix from Thomas Gleixner:
"A single fix for a thinko in the raw timekeeper update which causes
clock MONOTONIC_RAW to run with erratically increased frequency"
* 'timers-urgent-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip:
time: Fix ktime_get_raw() incorrect base accumulation
If a zero for the number of lines manages to slip through, scroll()
may underflow some offset calculations, causing accesses outside the
video memory.
Make the check in __putstr() more pessimistic to prevent that.
Signed-off-by: Jan H. Schönherr <jschoenh@amazon.de>
Cc: H. Peter Anvin <hpa@zytor.com>
Cc: Kees Cook <keescook@chromium.org>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Link: http://lkml.kernel.org/r/1503858223-14983-1-git-send-email-jschoenh@amazon.de
Signed-off-by: Ingo Molnar <mingo@kernel.org>
If a restartable syscall is called using the indirect o32 syscall
handler - eg: syscall(__NR_waitid, ...), then it is possible for the
incorrect arguments to be passed to the syscall after it has been
restarted. This is because the syscall handler tries to shift all the
registers down one place in pt_regs so that when the syscall is restarted,
the "real" syscall is called instead. Unfortunately it only shifts the
arguments passed in registers, not the arguments on the user stack. This
causes the 4th argument to be duplicated when the syscall is restarted.
Fix by removing all the pt_regs shifting so that the indirect syscall
handler is called again when the syscall is restarted. The comment "some
syscalls like execve get their arguments from struct pt_regs" is long
out of date so this should now be safe.
Signed-off-by: James Cowgill <James.Cowgill@imgtec.com>
Reviewed-by: James Hogan <james.hogan@imgtec.com>
Tested-by: James Hogan <james.hogan@imgtec.com>
Cc: linux-mips@linux-mips.org
Patchwork: https://patchwork.linux-mips.org/patch/15856/
Signed-off-by: Ralf Baechle <ralf@linux-mips.org>
Pull perf fixes from Thomas Gleixner:
- Prevent a potential inconistency in the perf user space access which
might lead to evading sanity checks.
- Prevent perf recording function trace entries twice
* 'perf-urgent-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip:
perf/ftrace: Fix double traces of perf on ftrace:function
perf/core: Fix potential double-fetch bug
In comqit fc6eead7c1e2 ("time: Clean up CLOCK_MONOTONIC_RAW time
handling"), the following code got mistakenly added to the update of the
raw timekeeper:
/* Update the monotonic raw base */
seconds = tk->raw_sec;
nsec = (u32)(tk->tkr_raw.xtime_nsec >> tk->tkr_raw.shift);
tk->tkr_raw.base = ns_to_ktime(seconds * NSEC_PER_SEC + nsec);
Which adds the raw_sec value and the shifted down raw xtime_nsec to the
base value.
But the read function adds the shifted down tk->tkr_raw.xtime_nsec value
another time, The result of this is that ktime_get_raw() users (which are
all internal users) see the raw time move faster then it should (the rate
at which can vary with the current size of tkr_raw.xtime_nsec), which has
resulted in at least problems with graphics rendering performance.
The change tried to match the monotonic base update logic:
seconds = (u64)(tk->xtime_sec + tk->wall_to_monotonic.tv_sec);
nsec = (u32) tk->wall_to_monotonic.tv_nsec;
tk->tkr_mono.base = ns_to_ktime(seconds * NSEC_PER_SEC + nsec);
Which adds the wall_to_monotonic.tv_nsec value, but not the
tk->tkr_mono.xtime_nsec value to the base.
To fix this, simplify the tkr_raw.base accumulation to only accumulate the
raw_sec portion, and do not include the tkr_raw.xtime_nsec portion, which
will be added at read time.
Fixes: fc6eead7c1e2 ("time: Clean up CLOCK_MONOTONIC_RAW time handling")
Reported-and-tested-by: Chris Wilson <chris@chris-wilson.co.uk>
Signed-off-by: John Stultz <john.stultz@linaro.org>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Cc: Prarit Bhargava <prarit@redhat.com>
Cc: Kevin Brodsky <kevin.brodsky@arm.com>
Cc: Richard Cochran <richardcochran@gmail.com>
Cc: Stephen Boyd <stephen.boyd@linaro.org>
Cc: Will Deacon <will.deacon@arm.com>
Cc: Miroslav Lichvar <mlichvar@redhat.com>
Cc: Daniel Mentz <danielmentz@google.com>
Link: http://lkml.kernel.org/r/1503701824-1645-1-git-send-email-john.stultz@linaro.org
The current slack space is not enough for LZ4, which has a worst case
overhead of 0.4% for data that cannot be further compressed. With
an LZ4 compressed kernel with an embedded initrd, the output is likely
to overwrite the input.
Increase the slack space to avoid that.
Signed-off-by: Jan H. Schönherr <jschoenh@amazon.de>
Cc: H. Peter Anvin <hpa@zytor.com>
Cc: Kees Cook <keescook@chromium.org>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Link: http://lkml.kernel.org/r/1503842124-29718-1-git-send-email-jschoenh@amazon.de
Signed-off-by: Ingo Molnar <mingo@kernel.org>
Since commit 669c4092225f ("MIPS: Give __secure_computing() access to
syscall arguments."), upon syscall entry when seccomp is enabled,
syscall_trace_enter() passes a carefully prepared struct seccomp_data
containing syscall arguments to __secure_computing(). Unfortunately it
directly uses mips_get_syscall_arg() and fails to take into account the
indirect O32 system calls (i.e. syscall(2)) which put the system call
number in a0 and have the arguments shifted up by one entry.
We can't just revert that commit as samples/bpf/tracex5 would break
again, so use syscall_get_arguments() which already takes indirect
syscalls into account instead of directly using mips_get_syscall_arg(),
similar to what populate_seccomp_data() does.
This also removes the redundant error checking of the
mips_get_syscall_arg() return value (get_user() already zeroes the
result if an argument from the stack can't be loaded).
Reported-by: James Cowgill <James.Cowgill@imgtec.com>
Fixes: 669c4092225f ("MIPS: Give __secure_computing() access to syscall arguments.")
Signed-off-by: James Hogan <james.hogan@imgtec.com>
Reviewed-by: Kees Cook <keescook@chromium.org>
Cc: David Daney <david.daney@cavium.com>
Cc: Andy Lutomirski <luto@amacapital.net>
Cc: Will Drewry <wad@chromium.org>
Cc: Oleg Nesterov <oleg@redhat.com>
Cc: Alexei Starovoitov <ast@kernel.org>
Cc: Daniel Borkmann <daniel@iogearbox.net>
Cc: netdev@vger.kernel.org
Cc: linux-kernel@vger.kernel.org
Cc: linux-mips@linux-mips.org
Patchwork: https://patchwork.linux-mips.org/patch/16994/
Signed-off-by: Ralf Baechle <ralf@linux-mips.org>
Pull cifs version warning fix from Steve French:
"As requested, additional kernel warning messages to clarify the
default dialect changes"
[ There is still some discussion about exactly which version should be
the new default. Longer-term we have auto-negotiation coming, but
that's not there yet.. - Linus ]
* 'for-next' of git://git.samba.org/sfrench/cifs-2.6:
Fix warning messages when mounting to older servers
When running perf on the ftrace:function tracepoint, there is a bug
which can be reproduced by:
perf record -e ftrace:function -a sleep 20 &
perf record -e ftrace:function ls
perf script
ls 10304 [005] 171.853235: ftrace:function:
perf_output_begin
ls 10304 [005] 171.853237: ftrace:function:
perf_output_begin
ls 10304 [005] 171.853239: ftrace:function:
task_tgid_nr_ns
ls 10304 [005] 171.853240: ftrace:function:
task_tgid_nr_ns
ls 10304 [005] 171.853242: ftrace:function:
__task_pid_nr_ns
ls 10304 [005] 171.853244: ftrace:function:
__task_pid_nr_ns
We can see that all the function traces are doubled.
The problem is caused by the inconsistency of the register
function perf_ftrace_event_register() with the probe function
perf_ftrace_function_call(). The former registers one probe
for every perf_event. And the latter handles all perf_events
on the current cpu. So when two perf_events on the current cpu,
the traces of them will be doubled.
So this patch adds an extra parameter "event" for perf_tp_event,
only send sample data to this event when it's not NULL.
Signed-off-by: Zhou Chengming <zhouchengming1@huawei.com>
Reviewed-by: Jiri Olsa <jolsa@kernel.org>
Acked-by: Steven Rostedt (VMware) <rostedt@goodmis.org>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: acme@kernel.org
Cc: alexander.shishkin@linux.intel.com
Cc: huawei.libin@huawei.com
Link: http://lkml.kernel.org/r/1503668977-12526-1-git-send-email-zhouchengming1@huawei.com
Signed-off-by: Ingo Molnar <mingo@kernel.org>
When a timer base is idle, it is forwarded when a new timer is added
to ensure that granularity does not become excessive. When not idle,
the timer tick is expected to increment the base.
However there are several problems:
- If an existing timer is modified, the base is forwarded only after
the index is calculated.
- The base is not forwarded by add_timer_on.
- There is a window after a timer is restarted from a nohz idle, after
it is marked not-idle and before the timer tick on this CPU, where a
timer may be added but the ancient base does not get forwarded.
These result in excessive granularity (a 1 jiffy timeout can blow out
to 100s of jiffies), which cause the rcu lockup detector to trigger,
among other things.
Fix this by keeping track of whether the timer base has been idle
since it was last run or forwarded, and if so then forward it before
adding a new timer.
There is still a case where mod_timer optimises the case of a pending
timer mod with the same expiry time, where the timer can see excessive
granularity relative to the new, shorter interval. A comment is added,
but it's not changed because it is an important fastpath for
networking.
This has been tested and found to fix the RCU softlockup messages.
Testing was also done with tracing to measure requested versus
achieved wakeup latencies for all non-deferrable timers in an idle
system (with no lockup watchdogs running). Wakeup latency relative to
absolute latency is calculated (note this suffers from round-up skew
at low absolute times) and analysed:
max avg std
upstream 506.0 1.20 4.68
patched 2.0 1.08 0.15
The bug was noticed due to the lockup detector Kconfig changes
dropping it out of people's .configs and resulting in larger base
clk skew When the lockup detectors are enabled, no CPU can go idle for
longer than 4 seconds, which limits the granularity errors.
Sub-optimal timer behaviour is observable on a smaller scale in that
case:
max avg std
upstream 9.0 1.05 0.19
patched 2.0 1.04 0.11
Fixes: Fixes: a683f390b93f ("timers: Forward the wheel clock whenever possible")
Signed-off-by: Nicholas Piggin <npiggin@gmail.com>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Tested-by: Jonathan Cameron <Jonathan.Cameron@huawei.com>
Tested-by: David Miller <davem@davemloft.net>
Cc: dzickus@redhat.com
Cc: sfr@canb.auug.org.au
Cc: mpe@ellerman.id.au
Cc: Stephen Boyd <sboyd@codeaurora.org>
Cc: linuxarm@huawei.com
Cc: abdhalee@linux.vnet.ibm.com
Cc: John Stultz <john.stultz@linaro.org>
Cc: akpm@linux-foundation.org
Cc: paulmck@linux.vnet.ibm.com
Cc: torvalds@linux-foundation.org
Cc: stable@vger.kernel.org
Link: http://lkml.kernel.org/r/20170822084348.21436-1-npiggin@gmail.com