tjh.dev
Linux kernel
============
There are several guides for kernel developers and users. These guides can
be rendered in a number of formats, like HTML and PDF. Please read
Documentation/admin-guide/README.rst first.
In order to build the documentation, use ``make htmldocs`` or
``make pdfdocs``. The formatted documentation can also be read online at:
https://www.kernel.org/doc/html/latest/
There are various text files in the Documentation/ subdirectory,
several of them using the Restructured Text markup notation.
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.
Linux kernel mirror (for testing)
git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git
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To pick the changes in:
344c6c804703 ("KVM/Hyper-V: Add new KVM capability KVM_CAP_HYPERV_DIRECT_TLBFLUSH")
dee04eee9182 ("KVM: RISC-V: Add KVM_REG_RISCV for ONE_REG interface")
These trigger the rebuild of this object:
CC /tmp/build/perf/trace/beauty/ioctl.o
But do not result in any change in tooling, as the additions are not
being used in any table generatator.
This silences this perf build warning:
Warning: Kernel ABI header at 'tools/include/uapi/linux/kvm.h' differs from latest version at 'include/uapi/linux/kvm.h'
diff -u tools/include/uapi/linux/kvm.h include/uapi/linux/kvm.h
Cc: Adrian Hunter <adrian.hunter@intel.com>
Cc: Anup Patel <Anup.Patel@wdc.com>
Cc: Jiri Olsa <jolsa@kernel.org>
Cc: Namhyung Kim <namhyung@kernel.org>
Cc: Paolo Bonzini <pbonzini@redhat.com>
Cc: Paul Walmsley <paul.walmsley@sifive.com>
Cc: Tianyu Lan <Tianyu.Lan@microsoft.com>
Link: https://lkml.kernel.org/n/tip-d1v48a0qfoe98u5v9tn3mu5u@git.kernel.org
Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>
To pick the changes in:
0cb8410b90e7 ("kvm: svm: Intercept RDPRU")
That trigger a rebuild in too in tooling:
CC /tmp/build/perf/arch/x86/util/kvm-stat.o
But this time around no changes in tooling results, as SVM_EXIT_RDPRU
wasn't added to SVM_EXIT_REASONS, that is used in kvm-stat.c.
And addresses this perf build warnings:
Warning: Kernel ABI header at 'tools/arch/x86/include/uapi/asm/svm.h' differs from latest version at 'arch/x86/include/uapi/asm/svm.h'
diff -u tools/arch/x86/include/uapi/asm/svm.h arch/x86/include/uapi/asm/svm.h
Cc: Adrian Hunter <adrian.hunter@intel.com>
Cc: Jim Mattson <jmattson@google.com>
Cc: Jiri Olsa <jolsa@kernel.org>
Cc: Namhyung Kim <namhyung@kernel.org>
Cc: Paolo Bonzini <pbonzini@redhat.com>
Link: https://lkml.kernel.org/n/tip-pqzkt1hmfpqph3ts8i6zzmim@git.kernel.org
Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>
To pick the changes in:
bf653b78f960 ("KVM: vmx: Introduce handle_unexpected_vmexit and handle WAITPKG vmexit")
That trigger these changes in tooling:
CC /tmp/build/perf/arch/x86/util/kvm-stat.o
INSTALL GTK UI
DESCEND plugins
make[3]: Nothing to be done for '/tmp/build/perf/plugins/libtraceevent-dynamic-list'.
INSTALL trace_plugins
LD /tmp/build/perf/arch/x86/util/perf-in.o
LD /tmp/build/perf/arch/x86/perf-in.o
LD /tmp/build/perf/arch/perf-in.o
LD /tmp/build/perf/perf-in.o
LINK /tmp/build/perf/perf
And this is not just because that header is included, kvm-stat.c
uses the VMX_EXIT_REASONS define and it got changed by the above cset.
And addresses this perf build warnings:
Warning: Kernel ABI header at 'tools/arch/x86/include/uapi/asm/vmx.h' differs from latest version at 'arch/x86/include/uapi/asm/vmx.h'
diff -u tools/arch/x86/include/uapi/asm/vmx.h arch/x86/include/uapi/asm/vmx.h
Cc: Adrian Hunter <adrian.hunter@intel.com>
Cc: David Ahern <dsahern@gmail.com>
Cc: Jiri Olsa <jolsa@kernel.org>
Cc: Namhyung Kim <namhyung@kernel.org>
Cc: Paolo Bonzini <pbonzini@redhat.com>
Cc: Tao Xu <tao3.xu@intel.com>
Cc: Wang Nan <wangnan0@huawei.com>
Link: https://lkml.kernel.org/n/tip-gr1eel0hckmi5l3p2ewdpfxh@git.kernel.org
Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>
There is a memory leak problem in the failure paths of
build_cl_output(), so fix it.
Signed-off-by: Yunfeng Ye <yeyunfeng@huawei.com>
Acked-by: Jiri Olsa <jolsa@kernel.org>
Cc: Alexander Shishkin <alexander.shishkin@linux.intel.com>
Cc: Feilong Lin <linfeilong@huawei.com>
Cc: Hu Shiyuan <hushiyuan@huawei.com>
Cc: Mark Rutland <mark.rutland@arm.com>
Cc: Namhyung Kim <namhyung@kernel.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Link: http://lore.kernel.org/lkml/4d3c0178-5482-c313-98e1-f82090d2d456@huawei.com
Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>
slow_copyfile() opens the file by name, so "write" permissions must not
be removed in copyfile_mode_ns() before calling slow_copyfile().
Example:
Before:
$ sudo chmod +r /proc/kcore
$ sudo setcap "cap_sys_admin,cap_sys_ptrace,cap_syslog,cap_sys_rawio=ep" tools/perf/perf
$ tools/perf/perf buildid-cache -k /proc/kcore
Couldn't add /proc/kcore
After:
$ sudo chmod +r /proc/kcore
$ sudo setcap "cap_sys_admin,cap_sys_ptrace,cap_syslog,cap_sys_rawio=ep" tools/perf/perf
$ tools/perf/perf buildid-cache -v -k /proc/kcore
kcore added to build-id cache directory /home/ahunter/.debug/[kernel.kcore]/37e340b1b5a7cf4f57ba8de2bc777359588a957f/2019100709562289
Signed-off-by: Adrian Hunter <adrian.hunter@intel.com>
Acked-by: Jiri Olsa <jolsa@kernel.org>
Tested-by: Arnaldo Carvalho de Melo <acme@redhat.com>
Link: http://lore.kernel.org/lkml/20191007070221.11158-1-adrian.hunter@intel.com
Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>
Store SYMBOL_ANNOTATE_ERRNO__BPF_MISSING_BTF in variable *ret*, instead
of returning in the middle of the function and leaking multiple
resources: prog_linfo, btf, s and bfdf.
Addresses-Coverity-ID: 1454832 ("Structurally dead code")
Fixes: 11aad897f6d1 ("perf annotate: Don't return -1 for error when doing BPF disassembly")
Signed-off-by: Gustavo A. R. Silva <gustavo@embeddedor.com>
Acked-by: Jiri Olsa <jolsa@kernel.org>
Cc: Alexander Shishkin <alexander.shishkin@linux.intel.com>
Cc: Mark Rutland <mark.rutland@arm.com>
Cc: Namhyung Kim <namhyung@kernel.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Link: http://lore.kernel.org/lkml/20191014171047.GA30850@embeddedor
Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>
Both build_mem_topology() and rm_rf_depth_pat() have resource leaks of
closedir() on the error paths.
Fix this by calling closedir() before function returns.
Fixes: e2091cedd51b ("perf tools: Add MEM_TOPOLOGY feature to perf data file")
Fixes: cdb6b0235f17 ("perf tools: Add pattern name checking to rm_rf")
Signed-off-by: Yunfeng Ye <yeyunfeng@huawei.com>
Acked-by: Jiri Olsa <jolsa@kernel.org>
Cc: Alexander Shishkin <alexander.shishkin@linux.intel.com>
Cc: Alexei Starovoitov <ast@kernel.org>
Cc: Alexey Budankov <alexey.budankov@linux.intel.com>
Cc: Andi Kleen <ak@linux.intel.com>
Cc: Daniel Borkmann <daniel@iogearbox.net>
Cc: Feilong Lin <linfeilong@huawei.com>
Cc: Hu Shiyuan <hushiyuan@huawei.com>
Cc: Igor Lubashev <ilubashe@akamai.com>
Cc: Kan Liang <kan.liang@linux.intel.com>
Cc: Mark Rutland <mark.rutland@arm.com>
Cc: Martin KaFai Lau <kafai@fb.com>
Cc: Namhyung Kim <namhyung@kernel.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Song Liu <songliubraving@fb.com>
Cc: Yonghong Song <yhs@fb.com>
Link: http://lore.kernel.org/lkml/cd5f7cd2-b80d-6add-20a1-32f4f43e0744@huawei.com
Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>
In the earlier fix for the memory overrun of id arrays I managed to typo
the wrong event in the fix.
Of course we need to close the current event in the loop, not the
original failing event.
The same test case as in the original patch still passes.
Fixes: 7834fa948beb ("perf evlist: Fix access of freed id arrays")
Signed-off-by: Andi Kleen <ak@linux.intel.com>
Cc: Jiri Olsa <jolsa@kernel.org>
Link: http://lore.kernel.org/lkml/20191011182140.8353-2-andi@firstfloor.org
Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>
The build of file libperf-jvmti.so succeeds but the resulting
object fails to load:
# ~/linux/tools/perf/perf record -k mono -- java \
-XX:+PreserveFramePointer \
-agentpath:/root/linux/tools/perf/libperf-jvmti.so \
hog 100000 123450
Error occurred during initialization of VM
Could not find agent library /root/linux/tools/perf/libperf-jvmti.so
in absolute path, with error:
/root/linux/tools/perf/libperf-jvmti.so: undefined symbol: _ctype
Add the missing _ctype symbol into the build script.
Fixes: 79743bc927f6 ("perf jvmti: Link against tools/lib/string.o to have weak strlcpy()")
Signed-off-by: Thomas Richter <tmricht@linux.ibm.com>
Cc: Heiko Carstens <heiko.carstens@de.ibm.com>
Cc: Vasily Gorbik <gor@linux.ibm.com>
Link: http://lore.kernel.org/lkml/20191008093841.59387-1-tmricht@linux.ibm.com
Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>
Pull tracing fixes from Steven Rostedt:
"A few tracing fixes:
- Remove lockdown from tracefs itself and moved it to the trace
directory. Have the open functions there do the lockdown checks.
- Fix a few races with opening an instance file and the instance
being deleted (Discovered during the lockdown updates). Kept
separate from the clean up code such that they can be backported to
stable easier.
- Clean up and consolidated the checks done when opening a trace
file, as there were multiple checks that need to be done, and it
did not make sense having them done in each open instance.
- Fix a regression in the record mcount code.
- Small hw_lat detector tracer fixes.
- A trace_pipe read fix due to not initializing trace_seq"
* tag 'trace-v5.4-rc2' of git://git.kernel.org/pub/scm/linux/kernel/git/rostedt/linux-trace:
tracing: Initialize iter->seq after zeroing in tracing_read_pipe()
tracing/hwlat: Don't ignore outer-loop duration when calculating max_latency
tracing/hwlat: Report total time spent in all NMIs during the sample
recordmcount: Fix nop_mcount() function
tracing: Do not create tracefs files if tracefs lockdown is in effect
tracing: Add locked_down checks to the open calls of files created for tracefs
tracing: Add tracing_check_open_get_tr()
tracing: Have trace events system open call tracing_open_generic_tr()
tracing: Get trace_array reference for available_tracers files
ftrace: Get a reference counter for the trace_array on filter files
tracefs: Revert ccbd54ff54e8 ("tracefs: Restrict tracefs when the kernel is locked down")
Merge tag 'hwmon-for-v5.4-rc3' of git://git.kernel.org/pub/scm/linux/kernel/git/groeck/linux-staging
Pull hwmon fixes from Guenter Roeck:
- Update/fix inspur-ipsps1 and k10temp Documentation
- Fix nct7904 driver
- Fix HWMON_P_MIN_ALARM mask in hwmon core
* tag 'hwmon-for-v5.4-rc3' of git://git.kernel.org/pub/scm/linux/kernel/git/groeck/linux-staging:
hwmon: docs: Extend inspur-ipsps1 title underline
hwmon: (nct7904) Add array fan_alarm and vsen_alarm to store the alarms in nct7904_data struct.
docs: hwmon: Include 'inspur-ipsps1.rst' into docs
hwmon: Fix HWMON_P_MIN_ALARM mask
hwmon: (k10temp) Update documentation and add temp2_input info
hwmon: (nct7904) Fix the incorrect value of vsen_mask in nct7904_data struct
A customer reported the following softlockup:
[899688.160002] NMI watchdog: BUG: soft lockup - CPU#0 stuck for 22s! [test.sh:16464]
[899688.160002] CPU: 0 PID: 16464 Comm: test.sh Not tainted 4.12.14-6.23-azure #1 SLE12-SP4
[899688.160002] RIP: 0010:up_write+0x1a/0x30
[899688.160002] Kernel panic - not syncing: softlockup: hung tasks
[899688.160002] RIP: 0010:up_write+0x1a/0x30
[899688.160002] RSP: 0018:ffffa86784d4fde8 EFLAGS: 00000257 ORIG_RAX: ffffffffffffff12
[899688.160002] RAX: ffffffff970fea00 RBX: 0000000000000001 RCX: 0000000000000000
[899688.160002] RDX: ffffffff00000001 RSI: 0000000000000080 RDI: ffffffff970fea00
[899688.160002] RBP: ffffffffffffffff R08: ffffffffffffffff R09: 0000000000000000
[899688.160002] R10: 0000000000000000 R11: 0000000000000000 R12: ffff8b59014720d8
[899688.160002] R13: ffff8b59014720c0 R14: ffff8b5901471090 R15: ffff8b5901470000
[899688.160002] tracing_read_pipe+0x336/0x3c0
[899688.160002] __vfs_read+0x26/0x140
[899688.160002] vfs_read+0x87/0x130
[899688.160002] SyS_read+0x42/0x90
[899688.160002] do_syscall_64+0x74/0x160
It caught the process in the middle of trace_access_unlock(). There is
no loop. So, it must be looping in the caller tracing_read_pipe()
via the "waitagain" label.
Crashdump analyze uncovered that iter->seq was completely zeroed
at this point, including iter->seq.seq.size. It means that
print_trace_line() was never able to print anything and
there was no forward progress.
The culprit seems to be in the code:
/* reset all but tr, trace, and overruns */
memset(&iter->seq, 0,
sizeof(struct trace_iterator) -
offsetof(struct trace_iterator, seq));
It was added by the commit 53d0aa773053ab182877 ("ftrace:
add logic to record overruns"). It was v2.6.27-rc1.
It was the time when iter->seq looked like:
struct trace_seq {
unsigned char buffer[PAGE_SIZE];
unsigned int len;
};
There was no "size" variable and zeroing was perfectly fine.
The solution is to reinitialize the structure after or without
zeroing.
Link: http://lkml.kernel.org/r/20191011142134.11997-1-pmladek@suse.com
Signed-off-by: Petr Mladek <pmladek@suse.com>
Signed-off-by: Steven Rostedt (VMware) <rostedt@goodmis.org>
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