Messages in this thread Patch in this message | | | From | Adrian Hunter <> | Subject | [PATCH RFC 2/5] perf: Add fork to the sideband ioctl | Date | Fri, 14 Apr 2023 11:22:57 +0300 |
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Support the case of output to an active event, and return an error if output is not possible in that case. Set PERF_RECORD_MISC_STATUS_ONLY to differentiate the ioctl status-only sideband event from a "real" sideband event.
Set the fork parent pid/tid to the real parent for a thread group leader, or to the thread group leader otherwise.
Signed-off-by: Adrian Hunter <adrian.hunter@intel.com> --- kernel/events/core.c | 88 ++++++++++++++++++++++++++++++++++++-------- 1 file changed, 73 insertions(+), 15 deletions(-)
diff --git a/kernel/events/core.c b/kernel/events/core.c index 5cbcc6851587..4e76596d3bfb 100644 --- a/kernel/events/core.c +++ b/kernel/events/core.c @@ -7948,6 +7948,54 @@ perf_iterate_sb(perf_iterate_f output, void *data, rcu_read_unlock(); } +typedef int (perf_output_f)(struct perf_event *event, void *data); + +static int perf_event_output_sb(struct perf_event *event, perf_output_f output, void *data) +{ + int err = -ENOENT; + + preempt_disable(); + + if (event->state != PERF_EVENT_STATE_ACTIVE || + !event_filter_match(event) || + READ_ONCE(event->oncpu) != smp_processor_id()) + goto out; + + err = output(event, data); +out: + preempt_enable(); + return err; +} + +struct perf_output_f_data { + perf_output_f *func; + void *data; +}; + +void perf_output_f_wrapper(struct perf_event *event, void *data) +{ + struct perf_output_f_data *f_data = data; + + f_data->func(event, f_data->data); +} + +static int perf_output_sb(perf_output_f output, void *data, + struct perf_event_context *task_ctx, + struct perf_event *event) +{ + struct perf_output_f_data f_data = { + .func = output, + .data = data, + }; + + if (event) + return perf_event_output_sb(event, output, data); + + perf_iterate_sb(perf_output_f_wrapper, &f_data, task_ctx); + + return 0; +} + /* * Clear all file-based filters at exec, they'll have to be * re-instated when/if these objects are mmapped again. @@ -8107,8 +8155,7 @@ static int perf_event_task_match(struct perf_event *event) event->attr.task; } -static void perf_event_task_output(struct perf_event *event, - void *data) +static int perf_event_task_output(struct perf_event *event, void *data) { struct perf_task_event *task_event = data; struct perf_output_handle handle; @@ -8117,7 +8164,7 @@ static void perf_event_task_output(struct perf_event *event, int ret, size = task_event->event_id.header.size; if (!perf_event_task_match(event)) - return; + return -ENOENT; perf_event_header__init_id(&task_event->event_id.header, &sample, event); @@ -8134,6 +8181,14 @@ static void perf_event_task_output(struct perf_event *event, task->real_parent); task_event->event_id.ptid = perf_event_pid(event, task->real_parent); + } else if (task_event->event_id.header.misc & PERF_RECORD_MISC_STATUS_ONLY) { + if (thread_group_leader(task)) { + task_event->event_id.ppid = perf_event_pid(event, task->real_parent); + task_event->event_id.ptid = perf_event_tid(event, task->real_parent); + } else { + task_event->event_id.ppid = perf_event_pid(event, task); + task_event->event_id.ptid = perf_event_pid(event, task); + } } else { /* PERF_RECORD_FORK */ task_event->event_id.ppid = perf_event_pid(event, current); task_event->event_id.ptid = perf_event_tid(event, current); @@ -8148,18 +8203,19 @@ static void perf_event_task_output(struct perf_event *event, perf_output_end(&handle); out: task_event->event_id.header.size = size; + return ret; } -static void perf_event_task(struct task_struct *task, - struct perf_event_context *task_ctx, - int new) +static int perf_event_task(struct task_struct *task, + struct perf_event_context *task_ctx, + int new, struct perf_event *event) { struct perf_task_event task_event; if (!atomic_read(&nr_comm_events) && !atomic_read(&nr_mmap_events) && !atomic_read(&nr_task_events)) - return; + return -ENOENT; task_event = (struct perf_task_event){ .task = task, @@ -8167,7 +8223,7 @@ static void perf_event_task(struct task_struct *task, .event_id = { .header = { .type = new ? PERF_RECORD_FORK : PERF_RECORD_EXIT, - .misc = 0, + .misc = event ? PERF_RECORD_MISC_STATUS_ONLY : 0, .size = sizeof(task_event.event_id), }, /* .pid */ @@ -8178,14 +8234,12 @@ static void perf_event_task(struct task_struct *task, }, }; - perf_iterate_sb(perf_event_task_output, - &task_event, - task_ctx); + return perf_output_sb(perf_event_task_output, &task_event, task_ctx, event); } void perf_event_fork(struct task_struct *task) { - perf_event_task(task, NULL, 1); + perf_event_task(task, NULL, 1, NULL); perf_event_namespaces(task); } @@ -12817,7 +12871,11 @@ EXPORT_SYMBOL_GPL(perf_event_create_kernel_counter); static int perf_event_emit_fork(struct perf_event *event, struct task_struct *task) { - return -EINVAL; + if (!event->attr.comm && !event->attr.mmap && !event->attr.mmap2 && + !event->attr.mmap_data && !event->attr.task) + return -EINVAL; + + return perf_event_task(task, NULL, 1, event); } static int perf_event_emit_namespaces(struct perf_event *event, struct task_struct *task) @@ -13115,7 +13173,7 @@ static void perf_event_exit_task_context(struct task_struct *child) * won't get any samples after PERF_RECORD_EXIT. We can however still * get a few PERF_RECORD_READ events. */ - perf_event_task(child, child_ctx, 0); + perf_event_task(child, child_ctx, 0, NULL); list_for_each_entry_safe(child_event, next, &child_ctx->event_list, event_entry) perf_event_exit_event(child_event, child_ctx); @@ -13157,7 +13215,7 @@ void perf_event_exit_task(struct task_struct *child) * child contexts and sets child->perf_event_ctxp[] to NULL. * At this point we need to send EXIT events to cpu contexts. */ - perf_event_task(child, NULL, 0); + perf_event_task(child, NULL, 0, NULL); } static void perf_free_event(struct perf_event *event, -- 2.34.1
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