linux.git/tools/perf/util/map.h, branch v4.12

perf symbols: Allow user probes on versioned symbols

2017-05-02T21:23:11+00:00

Symbol versioning, as in glibc, results in symbols being defined as:

  @[@]

(Note that "@@" identifies a default symbol, if the symbol name is
repeated.)

perf is currently unable to deal with this, and is unable to create user
probes at such symbols:

  --
  $ nm /lib/powerpc64le-linux-gnu/libpthread.so.0 | grep pthread_create
  0000000000008d30 t __pthread_create_2_1
  0000000000008d30 T pthread_create@@GLIBC_2.17
  $ /usr/bin/sudo perf probe -v -x /lib/powerpc64le-linux-gnu/libpthread.so.0 pthread_create
  probe-definition(0): pthread_create
  symbol:pthread_create file:(null) line:0 offset:0 return:0 lazy:(null)
  0 arguments
  Open Debuginfo file: /usr/lib/debug/lib/powerpc64le-linux-gnu/libpthread-2.19.so
  Try to find probe point from debuginfo.
  Probe point 'pthread_create' not found.
     Error: Failed to add events. Reason: No such file or directory (Code: -2)
  --

One is not able to specify the fully versioned symbol, either, due to
syntactic conflicts with other uses of "@" by perf:

  --
  $ /usr/bin/sudo perf probe -v -x /lib/powerpc64le-linux-gnu/libpthread.so.0 pthread_create@@GLIBC_2.17
  probe-definition(0): pthread_create@@GLIBC_2.17
  Semantic error :SRC@SRC is not allowed.
  0 arguments
     Error: Command Parse Error. Reason: Invalid argument (Code: -22)
  --

This patch ignores versioning for default symbols, thus allowing probes to be
created for these symbols:

  --
  $ /usr/bin/sudo ./perf probe -x /lib/powerpc64le-linux-gnu/libpthread.so.0 pthread_create
  Added new event:
     probe_libpthread:pthread_create (on pthread_create in /lib/powerpc64le-linux-gnu/libpthread-2.19.so)

  You can now use it in all perf tools, such as:

           perf record -e probe_libpthread:pthread_create -aR sleep 1

  $ /usr/bin/sudo ./perf record -e probe_libpthread:pthread_create -aR ./test 2
  [ perf record: Woken up 1 times to write data ]
  [ perf record: Captured and wrote 0.052 MB perf.data (2 samples) ]
  $ /usr/bin/sudo ./perf script
               test  2915 [000] 19124.260729: probe_libpthread:pthread_create: (3fff99248d38)
               test  2916 [000] 19124.260962: probe_libpthread:pthread_create: (3fff99248d38)
  $ /usr/bin/sudo ./perf probe --del=probe_libpthread:pthread_create
  Removed event: probe_libpthread:pthread_create
  --

Committer note:

Change the variable storing the result of strlen() to 'int', to fix the build
on debian:experimental-x-mipsel, fedora:24-x-ARC-uClibc, ubuntu:16.04-x-arm,
etc:

  util/symbol.c: In function 'symbol__match_symbol_name':
  util/symbol.c:422:11: error: comparison between signed and unsigned integer expressions [-Werror=sign-compare]
     if (len < versioning - name)
             ^

Signed-off-by: Paul A. Clarke 
Tested-by: Arnaldo Carvalho de Melo 
Acked-by: Masami Hiramatsu 
Cc: David Ahern 
Link: http://lkml.kernel.org/r/c2b18d9c-17f8-9285-4868-f58b6359ccac@us.ibm.com
Signed-off-by: Arnaldo Carvalho de Melo

perf map: Convert map_groups.refcnt from atomic_t to refcount_t

2017-03-03T22:07:15+00:00

The refcount_t type and corresponding API should be used instead of
atomic_t when the variable is used as a reference counter.

This allows to avoid accidental refcounter overflows that might lead to
use-after-free situations.

Signed-off-by: Elena Reshetova 
Signed-off-by: David Windsor 
Signed-off-by: Hans Liljestrand 
Signed-off-by: Kees Kook 
Tested-by: Arnaldo Carvalho de Melo 
Cc: Alexander Shishkin 
Cc: Andrew Morton 
Cc: David Windsor 
Cc: Greg Kroah-Hartman 
Cc: Hans Liljestrand 
Cc: Jiri Olsa 
Cc: Kees Kook 
Cc: Mark Rutland 
Cc: Matija Glavinic Pecotic 
Cc: Peter Zijlstra 
Cc: alsa-devel@alsa-project.org
Link: http://lkml.kernel.org/r/1487691303-31858-7-git-send-email-elena.reshetova@intel.com
[ Did the missing conversion of tests/thread-mg-share.c too ]
Signed-off-by: Arnaldo Carvalho de Melo

perf map: Convert map.refcnt from atomic_t to refcount_t

2017-03-03T22:07:15+00:00

The refcount_t type and corresponding API should be used instead of
atomic_t when the variable is used as a reference counter.

This allows to avoid accidental refcounter overflows that might lead to
use-after-free situations.

Signed-off-by: Elena Reshetova 
Signed-off-by: David Windsor 
Signed-off-by: Hans Liljestrand 
Signed-off-by: Kees Kook 
Tested-by: Arnaldo Carvalho de Melo 
Cc: Alexander Shishkin 
Cc: Andrew Morton 
Cc: David Windsor 
Cc: Greg Kroah-Hartman 
Cc: Hans Liljestrand 
Cc: Jiri Olsa 
Cc: Kees Kook 
Cc: Mark Rutland 
Cc: Matija Glavinic Pecotic 
Cc: Peter Zijlstra 
Cc: alsa-devel@alsa-project.org
Link: http://lkml.kernel.org/r/1487691303-31858-6-git-send-email-elena.reshetova@intel.com
Signed-off-by: Arnaldo Carvalho de Melo

perf symbols: Remove symbol_filter_t machinery

2016-09-05T14:14:50+00:00

We're not using it anymore, few users were, but we really could do
without it, simplify lots of functions by removing it.

Cc: Adrian Hunter 
Cc: David Ahern 
Cc: Jiri Olsa 
Cc: Masami Hiramatsu 
Cc: Namhyung Kim 
Cc: Wang Nan 
Link: http://lkml.kernel.org/n/tip-1zng8wdznn00iiz08bb7q3vn@git.kernel.org
Signed-off-by: Arnaldo Carvalho de Melo

perf unwind: Call unwind__prepare_access for forked thread

2016-07-04T23:27:25+00:00

Currently we call unwind__prepare_access for map event.  In case we
report fork event the thread inherits its parent's maps and
unwind__prepare_access is never called for the thread.

This causes unwind__get_entries seeing uninitialized
unwind_libunwind_ops and thus returning no callchain.

Adding unwind__prepare_access calls for fork even processing.

Signed-off-by: Jiri Olsa 
Cc: David Ahern 
Cc: He Kuang 
Cc: Namhyung Kim 
Cc: Peter Zijlstra 
Link: http://lkml.kernel.org/r/1467634583-29147-5-git-send-email-jolsa@kernel.org
Signed-off-by: Arnaldo Carvalho de Melo

perf maps: Introduce maps__find_symbol_by_name()

2015-09-30T21:34:25+00:00

Out of map_groups__find_symbol_by_name(), so that we can turn this later
one first into a call to maps__find_symbol_by_name(MAP__FUNCTION) +
MAP__VARIABLE, and then to just one call, we'll merge MAP__FUNCTION with
MAP__VARIABLE maps, to simplify the code.

Cc: Adrian Hunter 
Cc: Borislav Petkov 
Cc: David Ahern 
Cc: Frederic Weisbecker 
Cc: Jiri Olsa 
Cc: Namhyung Kim 
Cc: Stephane Eranian 
Cc: Wang Nan 
Link: http://lkml.kernel.org/n/tip-pvkar0jacqn92g148u9sqttt@git.kernel.org
Signed-off-by: Arnaldo Carvalho de Melo

perf symbols: Introduce map__is_(kernel,kmodule)()

2015-07-23T14:28:36+00:00

To, with members we already have, check if a kernel level map is for the
kernel proper or for a module.

Acked-by: David Ahern 
Cc: Adrian Hunter 
Cc: Borislav Petkov 
Cc: Frederic Weisbecker 
Cc: Jiri Olsa 
Cc: Namhyung Kim 
Cc: Stephane Eranian 
Link: http://lkml.kernel.org/n/tip-m5ic7h0z2crmtj7vi1a1rj3b@git.kernel.org
Signed-off-by: Arnaldo Carvalho de Melo

perf tools: Replace map->referenced & maps->removed_maps with map->refcnt

2015-06-16T13:34:38+00:00

Use just reference counts, so that when no more hist_entry instances
references a map and the thread instance goes away by processing a
PERF_RECORD_EXIT, we can delete the maps.

Cc: Adrian Hunter 
Cc: Borislav Petkov 
Cc: David Ahern 
Cc: Don Zickus 
Cc: Frederic Weisbecker 
Cc: Jiri Olsa 
Cc: Namhyung Kim 
Cc: Stephane Eranian 
Link: http://lkml.kernel.org/n/tip-oym7lfhcc7ss6xpz44h7nbxs@git.kernel.org
Signed-off-by: Arnaldo Carvalho de Melo

perf tools: Reference count struct map

2015-05-27T23:27:30+00:00

We have pointers to struct map instances in several places, like in the
hist_entry instances, so we need a way to know when we can destroy them,
otherwise we may either keep leaking them or end up referencing deleted
instances.

Start fixing it by reference counting them.

This patch puts the reference count for struct map in place, replacing
direct map__delete() calls with map__put() ones and then grabbing a
reference count when adding it to the maps struct where maps for a
struct thread are kept.

Next we'll grab reference counts when setting pointers to struct map
instances, in places like in the hist_entry code.

Cc: Adrian Hunter 
Cc: Borislav Petkov 
Cc: David Ahern 
Cc: Don Zickus 
Cc: Frederic Weisbecker 
Cc: Jiri Olsa 
Cc: Namhyung Kim 
Cc: Stephane Eranian 
Link: http://lkml.kernel.org/n/tip-wi19xczk0t2a41r1i2chuio5@git.kernel.org
Signed-off-by: Arnaldo Carvalho de Melo

perf tools: Protect accesses the map rbtrees with a rw lock

2015-05-27T23:25:16+00:00

To allow concurrent access, next step: refcount struct map instances, so
that we can ditch maps->removed_maps and stop leaking threads, maps,
then struct DSO needs the same treatment.

Cc: Adrian Hunter 
Cc: Borislav Petkov 
Cc: David Ahern 
Cc: Don Zickus 
Cc: Frederic Weisbecker 
Cc: Jiri Olsa 
Cc: Namhyung Kim 
Cc: Stephane Eranian 
Link: http://lkml.kernel.org/n/tip-o45w2w5dzrza38nzqxnqzhyf@git.kernel.org
Signed-off-by: Arnaldo Carvalho de Melo