[tip:perf/core] perf: Differentiate exec() and non-exec() comm events
From: tip-bot for Adrian Hunter
Date: Fri Jun 06 2014 - 08:21:51 EST
Commit-ID: 82b897782d10fcc4930c9d4a15b175348fdd2871
Gitweb: http://git.kernel.org/tip/82b897782d10fcc4930c9d4a15b175348fdd2871
Author: Adrian Hunter <adrian.hunter@xxxxxxxxx>
AuthorDate: Wed, 28 May 2014 11:45:04 +0300
Committer: Ingo Molnar <mingo@xxxxxxxxxx>
CommitDate: Fri, 6 Jun 2014 07:56:22 +0200
perf: Differentiate exec() and non-exec() comm events
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@xxxxxxxxx>
Signed-off-by: Peter Zijlstra <peterz@xxxxxxxxxxxxx>
Link: http://lkml.kernel.org/r/537D9EBE.7030806@xxxxxxxxx
Cc: Paul Mackerras <paulus@xxxxxxxxx>
Cc: Dave Jones <davej@xxxxxxxxxx>
Cc: Arnaldo Carvalho de Melo <acme@xxxxxxxxxx>
Cc: David Ahern <dsahern@xxxxxxxxx>
Cc: Jiri Olsa <jolsa@xxxxxxxxxx>
Cc: Alexander Viro <viro@xxxxxxxxxxxxxxxxxx>
Cc: Linus Torvalds <torvalds@xxxxxxxxxxxxxxxxxxxx>
Cc: linux-fsdevel@xxxxxxxxxxxxxxx
Cc: linux-kernel@xxxxxxxxxxxxxxx
Signed-off-by: Ingo Molnar <mingo@xxxxxxxxxx>
---
fs/exec.c | 6 +++---
include/linux/perf_event.h | 4 ++--
include/linux/sched.h | 6 +++++-
include/uapi/linux/perf_event.h | 9 +++++++--
kernel/events/core.c | 4 ++--
5 files changed, 19 insertions(+), 10 deletions(-)
diff --git a/fs/exec.c b/fs/exec.c
index a038a41..a3d33fe 100644
--- a/fs/exec.c
+++ b/fs/exec.c
@@ -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
diff --git a/include/linux/perf_event.h b/include/linux/perf_event.h
index b4c1d46..707617a 100644
--- a/include/linux/perf_event.h
+++ b/include/linux/perf_event.h
@@ -707,7 +707,7 @@ extern int perf_register_guest_info_callbacks(struct perf_guest_info_callbacks *
extern int perf_unregister_guest_info_callbacks(struct perf_guest_info_callbacks *callbacks);
extern void perf_event_exec(void);
-extern void perf_event_comm(struct task_struct *tsk);
+extern void perf_event_comm(struct task_struct *tsk, bool exec);
extern void perf_event_fork(struct task_struct *tsk);
/* Callchains */
@@ -815,7 +815,7 @@ static inline int perf_unregister_guest_info_callbacks
static inline void perf_event_mmap(struct vm_area_struct *vma) { }
static inline void perf_event_exec(void) { }
-static inline void perf_event_comm(struct task_struct *tsk) { }
+static inline void perf_event_comm(struct task_struct *tsk, bool exec) { }
static inline void perf_event_fork(struct task_struct *tsk) { }
static inline void perf_event_init(void) { }
static inline int perf_swevent_get_recursion_context(void) { return -1; }
diff --git a/include/linux/sched.h b/include/linux/sched.h
index 221b2bd..ad86e1d 100644
--- a/include/linux/sched.h
+++ b/include/linux/sched.h
@@ -2379,7 +2379,11 @@ extern long do_fork(unsigned long, unsigned long, unsigned long, int __user *, i
struct task_struct *fork_idle(int);
extern pid_t kernel_thread(int (*fn)(void *), void *arg, unsigned long flags);
-extern void set_task_comm(struct task_struct *tsk, const char *from);
+extern void __set_task_comm(struct task_struct *tsk, const char *from, bool exec);
+static inline void set_task_comm(struct task_struct *tsk, const char *from)
+{
+ __set_task_comm(tsk, from, false);
+}
extern char *get_task_comm(char *to, struct task_struct *tsk);
#ifdef CONFIG_SMP
diff --git a/include/uapi/linux/perf_event.h b/include/uapi/linux/perf_event.h
index d9cd853..5312fae 100644
--- a/include/uapi/linux/perf_event.h
+++ b/include/uapi/linux/perf_event.h
@@ -302,8 +302,8 @@ struct perf_event_attr {
exclude_callchain_kernel : 1, /* exclude kernel callchains */
exclude_callchain_user : 1, /* exclude user callchains */
mmap2 : 1, /* include mmap with inode data */
-
- __reserved_1 : 40;
+ comm_exec : 1, /* flag comm events that are due to an exec */
+ __reserved_1 : 39;
union {
__u32 wakeup_events; /* wakeup every n events */
@@ -502,7 +502,12 @@ struct perf_event_mmap_page {
#define PERF_RECORD_MISC_GUEST_KERNEL (4 << 0)
#define PERF_RECORD_MISC_GUEST_USER (5 << 0)
+/*
+ * PERF_RECORD_MISC_MMAP_DATA and PERF_RECORD_MISC_COMM_EXEC are used on
+ * different events so can reuse the same bit position.
+ */
#define PERF_RECORD_MISC_MMAP_DATA (1 << 13)
+#define PERF_RECORD_MISC_COMM_EXEC (1 << 13)
/*
* Indicates that the content of PERF_SAMPLE_IP points to
* the actual instruction that triggered the event. See also
diff --git a/kernel/events/core.c b/kernel/events/core.c
index 8fac205..7da5e56 100644
--- a/kernel/events/core.c
+++ b/kernel/events/core.c
@@ -5090,7 +5090,7 @@ static void perf_event_comm_event(struct perf_comm_event *comm_event)
NULL);
}
-void perf_event_comm(struct task_struct *task)
+void perf_event_comm(struct task_struct *task, bool exec)
{
struct perf_comm_event comm_event;
@@ -5104,7 +5104,7 @@ void perf_event_comm(struct task_struct *task)
.event_id = {
.header = {
.type = PERF_RECORD_COMM,
- .misc = 0,
+ .misc = exec ? PERF_RECORD_MISC_COMM_EXEC : 0,
/* .size */
},
/* .pid */
--
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