linux-stable.git/tools/perf/util, branch linux-4.1.y

perf report: Ensure the perf DSO mapping matches what libdw sees

2018-05-23T01:36:28+00:00

[ Upstream commit 2538b9e2450ae255337c04356e9e0f8cb9ec48d9 ]

In some situations the libdw unwinder stopped working properly.  I.e.
with libunwind we see:

~~~~~
heaptrack_gui  2228 135073.400112:     641314 cycles:
	            e8ed _dl_fixup (/usr/lib/ld-2.25.so)
	           15f06 _dl_runtime_resolve_sse_vex (/usr/lib/ld-2.25.so)
	           ed94c KDynamicJobTracker::KDynamicJobTracker (/home/milian/projects/compiled/kf5/lib64/libKF5KIOWidgets.so.5.35.0)
	           608f3 _GLOBAL__sub_I_kdynamicjobtracker.cpp (/home/milian/projects/compiled/kf5/lib64/libKF5KIOWidgets.so.5.35.0)
	            f199 call_init.part.0 (/usr/lib/ld-2.25.so)
	            f2a5 _dl_init (/usr/lib/ld-2.25.so)
	             db9 _dl_start_user (/usr/lib/ld-2.25.so)
~~~~~

But with libdw and without this patch this sample is not properly
unwound:

~~~~~
heaptrack_gui  2228 135073.400112:     641314 cycles:
	            e8ed _dl_fixup (/usr/lib/ld-2.25.so)
	           15f06 _dl_runtime_resolve_sse_vex (/usr/lib/ld-2.25.so)
	           ed94c KDynamicJobTracker::KDynamicJobTracker (/home/milian/projects/compiled/kf5/lib64/libKF5KIOWidgets.so.5.35.0)
~~~~~

Debug output showed me that libdw found a module for the last frame
address, but it thinks it belongs to /usr/lib/ld-2.25.so. This patch
double-checks what libdw sees and what perf knows. If the mappings
mismatch, we now report the elf known to perf. This fixes the situation
above, and the libdw unwinder produces the same stack as libunwind.

Signed-off-by: Milian Wolff 
Cc: Jiri Olsa 
Cc: Namhyung Kim 
Link: http://lkml.kernel.org/r/20170602143753.16907-1-milian.wolff@kdab.com
Signed-off-by: Arnaldo Carvalho de Melo 
Signed-off-by: Sasha Levin

perf session: Don't rely on evlist in pipe mode

2018-05-23T01:33:45+00:00

[ Upstream commit 0973ad97c187e06aece61f685b9c3b2d93290a73 ]

Session sets a number parameters that rely on evlist. These parameters
are not used in pipe-mode and should not be set, since evlist is
unavailable. Fix that.

Signed-off-by: David Carrillo-Cisneros 
Acked-by: Jiri Olsa 
Cc: Alexander Shishkin 
Cc: Andi Kleen 
Cc: He Kuang 
Cc: Masami Hiramatsu 
Cc: Paul Turner 
Cc: Peter Zijlstra 
Cc: Simon Que 
Cc: Stephane Eranian 
Cc: Wang Nan 
Link: http://lkml.kernel.org/r/20170410201432.24807-6-davidcc@google.com
[ Check if file != NULL in perf_session__new(), like when used by builtin-top.c ]
Signed-off-by: Arnaldo Carvalho de Melo 
Signed-off-by: Sasha Levin

perf inject: Copy events when reordering events in pipe mode

2018-05-23T01:33:45+00:00

[ Upstream commit 1e0d4f0200e4dbdfc38d818f329d8a0955f7c6f5 ]

__perf_session__process_pipe_events reuses the same memory buffer to
process all events in the pipe.

When reordering is needed (e.g. -b option), events are not immediately
flushed, but kept around until reordering is possible, causing
memory corruption.

The problem is usually observed by a "Unknown sample error" output. It
can easily be reproduced by:

  perf record -o - noploop | perf inject -b > output

Committer testing:

Before:

  $ perf record -o - stress -t 2 -c 2 | perf inject -b > /dev/null
  stress: info: [8297] dispatching hogs: 2 cpu, 0 io, 0 vm, 0 hdd
  stress: info: [8297] successful run completed in 2s
  [ perf record: Woken up 3 times to write data ]
  [ perf record: Captured and wrote 0.000 MB - ]
  Warning:
  Found 1 unknown events!

  Is this an older tool processing a perf.data file generated by a more recent tool?

  If that is not the case, consider reporting to linux-kernel@vger.kernel.org.

  $

After:

  $ perf record -o - stress -t 2 -c 2 | perf inject -b > /dev/null
  stress: info: [9027] dispatching hogs: 2 cpu, 0 io, 0 vm, 0 hdd
  stress: info: [9027] successful run completed in 2s
  [ perf record: Woken up 3 times to write data ]
  [ perf record: Captured and wrote 0.000 MB - ]
  no symbols found in /usr/bin/stress, maybe install a debug package?
  no symbols found in /usr/bin/stress, maybe install a debug package?
  $

Signed-off-by: David Carrillo-Cisneros 
Tested-by: Arnaldo Carvalho de Melo 
Acked-by: Jiri Olsa 
Cc: Alexander Shishkin 
Cc: Andi Kleen 
Cc: He Kuang 
Cc: Masami Hiramatsu 
Cc: Paul Turner 
Cc: Peter Zijlstra 
Cc: Simon Que 
Cc: Stephane Eranian 
Cc: Wang Nan 
Link: http://lkml.kernel.org/r/20170410201432.24807-3-davidcc@google.com
Signed-off-by: Arnaldo Carvalho de Melo 
Signed-off-by: Sasha Levin

perf tools: Make perf_event__synthesize_mmap_events() scale

2018-05-23T01:33:43+00:00

[ Upstream commit 88b897a30c525c2eee6e7f16e1e8d0f18830845e ]

This patch significantly improves the execution time of
perf_event__synthesize_mmap_events() when running perf record on systems
where processes have lots of threads.

It just happens that cat /proc/pid/maps support uses a O(N^2) algorithm to
generate each map line in the maps file.  If you have 1000 threads, then you
have necessarily 1000 stacks.  For each vma, you need to check if it
corresponds to a thread's stack.  With a large number of threads, this can take
a very long time. I have seen latencies >> 10mn.

As of today, perf does not use the fact that a mapping is a stack, therefore we
can work around the issue by using /proc/pid/tasks/pid/maps.  This entry does
not try to map a vma to stack and is thus much faster with no loss of
functonality.

The proc-map-timeout logic is kept in case users still want some upper limit.

In V2, we fix the file path from /proc/pid/tasks/pid/maps to actual
/proc/pid/task/pid/maps, tasks -> task.  Thanks Arnaldo for catching this.

Committer note:

This problem seems to have been elliminated in the kernel since commit :
b18cb64ead40 ("fs/proc: Stop trying to report thread stacks").

Signed-off-by: Stephane Eranian 
Acked-by: Jiri Olsa 
Cc: Andy Lutomirski 
Cc: Namhyung Kim 
Cc: Peter Zijlstra 
Link: http://lkml.kernel.org/r/20170315135059.GC2177@redhat.com
Link: http://lkml.kernel.org/r/1489598233-25586-1-git-send-email-eranian@google.com
Signed-off-by: Arnaldo Carvalho de Melo 
Signed-off-by: Sasha Levin

perf symbols: Fix symbols__fixup_end heuristic for corner cases

2018-01-17T17:55:36+00:00

[ Upstream commit e7ede72a6d40cb3a30c087142d79381ca8a31dab ]

The current symbols__fixup_end() heuristic for the last entry in the rb
tree is suboptimal as it leads to not being able to recognize the symbol
in the call graph in a couple of corner cases, for example:

 i) If the symbol has a start address (f.e. exposed via kallsyms)
    that is at a page boundary, then the roundup(curr->start, 4096)
    for the last entry will result in curr->start == curr->end with
    a symbol length of zero.

ii) If the symbol has a start address that is shortly before a page
    boundary, then also here, curr->end - curr->start will just be
    very few bytes, where it's unrealistic that we could perform a
    match against.

Instead, change the heuristic to roundup(curr->start, 4096) + 4096, so
that we can catch such corner cases and have a better chance to find
that specific symbol. It's still just best effort as the real end of the
symbol is unknown to us (and could even be at a larger offset than the
current range), but better than the current situation.

Alexei reported that he recently run into case i) with a JITed eBPF
program (these are all page aligned) as the last symbol which wasn't
properly shown in the call graph (while other eBPF program symbols in
the rb tree were displayed correctly). Since this is a generic issue,
lets try to improve the heuristic a bit.

Reported-and-Tested-by: Alexei Starovoitov 
Signed-off-by: Daniel Borkmann 
Fixes: 2e538c4a1847 ("perf tools: Improve kernel/modules symbol lookup")
Link: http://lkml.kernel.org/r/bb5c80d27743be6f12afc68405f1956a330e1bc9.1489614365.git.daniel@iogearbox.net
Signed-off-by: Arnaldo Carvalho de Melo 
Signed-off-by: Sasha Levin

perf symbols: Robustify reading of build-id from sysfs

2017-09-10T20:35:56+00:00

[ Upstream commit 7934c98a6e04028eb34c1293bfb5a6b0ab630b66 ]

Markus reported that perf segfaults when reading /sys/kernel/notes from
a kernel linked with GNU gold, due to what looks like a gold bug, so do
some bounds checking to avoid crashing in that case.

Reported-by: Markus Trippelsdorf 
Report-Link: http://lkml.kernel.org/r/20161219161821.GA294@x4
Cc: Adrian Hunter 
Cc: David Ahern 
Cc: Jiri Olsa 
Cc: Namhyung Kim 
Cc: Wang Nan 
Link: http://lkml.kernel.org/n/tip-ryhgs6a6jxvz207j2636w31c@git.kernel.org
Signed-off-by: Arnaldo Carvalho de Melo 
Signed-off-by: Sasha Levin

perf pmu: Fix misleadingly indented assignment (whitespace)

2017-07-31T17:37:53+00:00

[ Upstream commit d85ce830eef6c10d1e9617172dea4681f02b8424 ]

One line in perf_pmu__parse_unit() is indented wrongly, leading to a
warning (=> error) from gcc 6:

  util/pmu.c:156:3: error: statement is indented as if it were guarded by... [-Werror=misleading-indentation]

    sret = read(fd, alias->unit, UNIT_MAX_LEN);
    ^~~~

  util/pmu.c:153:2: note: ...this 'if' clause, but it is not
    if (fd == -1)
    ^~

Signed-off-by: Markus Trippelsdorf 
Acked-by: Ingo Molnar 
Cc: Ben Hutchings 
Cc: Matt Fleming 
Cc: Peter Zijlstra 
Fixes: 410136f5dd96 ("tools/perf/stat: Add event unit and scale support")
Link: http://lkml.kernel.org/r/20151214154440.GC1409@x4
Signed-off-by: Arnaldo Carvalho de Melo 
Signed-off-by: Sasha Levin

perf tools: Remove duplicate const qualifier

2017-07-31T17:37:53+00:00

[ Upstream commit 3b556bced46aa6b1873da7faa18eff235e896adc ]

Signed-off-by: Eric Engestrom 
Cc: Adrian Hunter 
Cc: David Ahern 
Cc: Peter Zijlstra 
Link: http://lkml.kernel.org/r/1461577678-29517-1-git-send-email-eric.engestrom@imgtec.com
Signed-off-by: Arnaldo Carvalho de Melo 
Signed-off-by: Sasha Levin

perf tools: Use readdir() instead of deprecated readdir_r()

2017-07-31T17:37:53+00:00

[ Upstream commit 7093b4c963cc4e344e490c774924a180602a7092 ]

The readdir() function is thread safe as long as just one thread uses a
DIR, which is the case when synthesizing events for pre-existing threads
by traversing /proc, so, to avoid breaking the build with glibc-2.23.90
(upcoming 2.24), use it instead of readdir_r().

See: http://man7.org/linux/man-pages/man3/readdir.3.html

"However, in modern implementations (including the glibc implementation),
concurrent calls to readdir() that specify different directory streams
are thread-safe.  In cases where multiple threads must read from the
same directory stream, using readdir() with external synchronization is
still preferable to the use of the deprecated readdir_r(3) function."

Noticed while building on a Fedora Rawhide docker container.

   CC       /tmp/build/perf/util/event.o
  util/event.c: In function '__event__synthesize_thread':
  util/event.c:466:2: error: 'readdir_r' is deprecated [-Werror=deprecated-declarations]
    while (!readdir_r(tasks, &dirent, &next) && next) {
    ^~~~~
  In file included from /usr/include/features.h:368:0,
                   from /usr/include/stdint.h:25,
                   from /usr/lib/gcc/x86_64-redhat-linux/6.0.0/include/stdint.h:9,
                   from /git/linux/tools/include/linux/types.h:6,
                   from util/event.c:1:
  /usr/include/dirent.h:189:12: note: declared here

Cc: Adrian Hunter 
Cc: David Ahern 
Cc: Jiri Olsa 
Cc: Namhyung Kim 
Cc: Wang Nan 
Link: http://lkml.kernel.org/n/tip-i1vj7nyjp2p750rirxgrfd3c@git.kernel.org
Signed-off-by: Arnaldo Carvalho de Melo 
Signed-off-by: Sasha Levin

perf scripting perl: Fix compile error with some perl5 versions

2017-07-31T17:37:53+00:00

[ Upstream commit d7dd112ea5cacf91ae72c0714c3b911eb6016fea ]

Fix below compile error:

  CC       util/scripting-engines/trace-event-perl.o
  In file included from /usr/lib/perl5/5.22.2/i686-linux/CORE/perl.h:5673:0,
                   from util/scripting-engines/trace-event-perl.c:31:
  /usr/lib/perl5/5.22.2/i686-linux/CORE/inline.h: In function 'S__is_utf8_char_slow':
  /usr/lib/perl5/5.22.2/i686-linux/CORE/inline.h:270:5: error: nested extern declaration of 'Perl___notused' [-Werror=nested-externs]
          dTHX;   /* The function called below requires thread context */
			     ^
  cc1: all warnings being treated as errors

After digging perl5 repository, I find out that we will meet this
compile error with perl from v5.21.1 to v5.25.4

Signed-off-by: Wang YanQing 
Acked-by: Jiri Olsa 
Link: http://lkml.kernel.org/r/20170212024655.GA15997@udknight
Signed-off-by: Arnaldo Carvalho de Melo 
Signed-off-by: Sasha Levin