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@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>
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5 changed files with 19 additions and 10 deletions
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@ -1046,13 +1046,13 @@ EXPORT_SYMBOL_GPL(get_task_comm);
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* so that a new one can be started
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*/
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void set_task_comm(struct task_struct *tsk, const char *buf)
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void __set_task_comm(struct task_struct *tsk, const char *buf, bool exec)
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{
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task_lock(tsk);
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trace_task_rename(tsk, buf);
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strlcpy(tsk->comm, buf, sizeof(tsk->comm));
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task_unlock(tsk);
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perf_event_comm(tsk);
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perf_event_comm(tsk, exec);
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}
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int flush_old_exec(struct linux_binprm * bprm)
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@ -1111,7 +1111,7 @@ void setup_new_exec(struct linux_binprm * bprm)
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set_dumpable(current->mm, suid_dumpable);
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perf_event_exec();
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set_task_comm(current, kbasename(bprm->filename));
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__set_task_comm(current, kbasename(bprm->filename), true);
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/* Set the new mm task size. We have to do that late because it may
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* depend on TIF_32BIT which is only updated in flush_thread() on
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@ -707,7 +707,7 @@ extern int perf_register_guest_info_callbacks(struct perf_guest_info_callbacks *
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extern int perf_unregister_guest_info_callbacks(struct perf_guest_info_callbacks *callbacks);
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extern void perf_event_exec(void);
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extern void perf_event_comm(struct task_struct *tsk);
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extern void perf_event_comm(struct task_struct *tsk, bool exec);
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extern void perf_event_fork(struct task_struct *tsk);
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/* Callchains */
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@ -815,7 +815,7 @@ static inline int perf_unregister_guest_info_callbacks
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static inline void perf_event_mmap(struct vm_area_struct *vma) { }
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static inline void perf_event_exec(void) { }
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static inline void perf_event_comm(struct task_struct *tsk) { }
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static inline void perf_event_comm(struct task_struct *tsk, bool exec) { }
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static inline void perf_event_fork(struct task_struct *tsk) { }
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static inline void perf_event_init(void) { }
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static inline int perf_swevent_get_recursion_context(void) { return -1; }
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@ -2379,7 +2379,11 @@ extern long do_fork(unsigned long, unsigned long, unsigned long, int __user *, i
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struct task_struct *fork_idle(int);
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extern pid_t kernel_thread(int (*fn)(void *), void *arg, unsigned long flags);
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extern void set_task_comm(struct task_struct *tsk, const char *from);
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extern void __set_task_comm(struct task_struct *tsk, const char *from, bool exec);
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static inline void set_task_comm(struct task_struct *tsk, const char *from)
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{
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__set_task_comm(tsk, from, false);
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}
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extern char *get_task_comm(char *to, struct task_struct *tsk);
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#ifdef CONFIG_SMP
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@ -302,8 +302,8 @@ struct perf_event_attr {
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exclude_callchain_kernel : 1, /* exclude kernel callchains */
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exclude_callchain_user : 1, /* exclude user callchains */
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mmap2 : 1, /* include mmap with inode data */
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__reserved_1 : 40;
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comm_exec : 1, /* flag comm events that are due to an exec */
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__reserved_1 : 39;
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union {
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__u32 wakeup_events; /* wakeup every n events */
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@ -502,7 +502,12 @@ struct perf_event_mmap_page {
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#define PERF_RECORD_MISC_GUEST_KERNEL (4 << 0)
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#define PERF_RECORD_MISC_GUEST_USER (5 << 0)
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/*
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* PERF_RECORD_MISC_MMAP_DATA and PERF_RECORD_MISC_COMM_EXEC are used on
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* different events so can reuse the same bit position.
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*/
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#define PERF_RECORD_MISC_MMAP_DATA (1 << 13)
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#define PERF_RECORD_MISC_COMM_EXEC (1 << 13)
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/*
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* Indicates that the content of PERF_SAMPLE_IP points to
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* the actual instruction that triggered the event. See also
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@ -5090,7 +5090,7 @@ static void perf_event_comm_event(struct perf_comm_event *comm_event)
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NULL);
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}
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void perf_event_comm(struct task_struct *task)
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void perf_event_comm(struct task_struct *task, bool exec)
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{
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struct perf_comm_event comm_event;
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@ -5104,7 +5104,7 @@ void perf_event_comm(struct task_struct *task)
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.event_id = {
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.header = {
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.type = PERF_RECORD_COMM,
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.misc = 0,
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.misc = exec ? PERF_RECORD_MISC_COMM_EXEC : 0,
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/* .size */
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},
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/* .pid */
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