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perf: Differentiate exec() and non-exec() comm events

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perf tools like 'perf report' can aggregate samples by comm strings,
which generally works.  However, there are other potential use-cases.
For example, to pair up 'calls' with 'returns' accurately (from branch
events like Intel BTS) it is necessary to identify whether the process
has exec'd.  Although a comm event is generated when an 'exec' happens
it is also generated whenever the comm string is changed on a whim
(e.g. by prctl PR_SET_NAME).  This patch adds a flag to the comm event
to differentiate one case from the other.

In order to determine whether the kernel supports the new flag, a
selection bit named 'exec' is added to struct perf_event_attr.  The
bit does nothing but will cause perf_event_open() to fail if the bit
is set on kernels that do not have it defined.

Signed-off-by: Adrian Hunter <adrian.hunter@intel.com>
Signed-off-by: Peter Zijlstra <peterz@infradead.org>
Link: http://lkml.kernel.org/r/537D9EBE.7030806@intel.com
Cc: Paul Mackerras <paulus@samba.org>
Cc: Dave Jones <davej@redhat.com>
Cc: Arnaldo Carvalho de Melo <acme@kernel.org>
Cc: David Ahern <dsahern@gmail.com>
Cc: Jiri Olsa <jolsa@redhat.com>
Cc: Alexander Viro <viro@zeniv.linux.org.uk>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: linux-fsdevel@vger.kernel.org
Cc: linux-kernel@vger.kernel.org
Signed-off-by: Ingo Molnar <mingo@kernel.org>
This commit is contained in:
Adrian Hunter
2014-05-28 11:45:04 +03:00
committed by Ingo Molnar
parent ec00010972
commit 82b897782d
5 changed files with 19 additions and 10 deletions
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6
fs/exec.c
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@@ -1046,13 +1046,13 @@ EXPORT_SYMBOL_GPL(get_task_comm);
* so that a new one can be started
*/
void set_task_comm(struct task_struct *tsk, const char *buf)
void __set_task_comm(struct task_struct *tsk, const char *buf, bool exec)
{
task_lock(tsk);
trace_task_rename(tsk, buf);
strlcpy(tsk->comm, buf, sizeof(tsk->comm));
task_unlock(tsk);
perf_event_comm(tsk);
perf_event_comm(tsk, exec);
}
int flush_old_exec(struct linux_binprm * bprm)
@@ -1111,7 +1111,7 @@ void setup_new_exec(struct linux_binprm * bprm)
set_dumpable(current->mm, suid_dumpable);
perf_event_exec();
set_task_comm(current, kbasename(bprm->filename));
__set_task_comm(current, kbasename(bprm->filename), true);
/* Set the new mm task size. We have to do that late because it may
* depend on TIF_32BIT which is only updated in flush_thread() on