Adds bit perf_event_attr::sigtrap, which can be set to cause events to send SIGTRAP (with si_code TRAP_PERF) to the task where the event occurred. To distinguish perf events and allow user space to decode si_perf (if set), the event type is set in si_errno. The primary motivation is to support synchronous signals on perf events in the task where an event (such as breakpoints) triggered. Link: https://lore.kernel.org/lkml/YBv3rAT566k+6zjg@xxxxxxxxxxxxxxxxxxxxxxxxxxxxxxx/ Suggested-by: Peter Zijlstra <peterz@xxxxxxxxxxxxx> Signed-off-by: Marco Elver <elver@xxxxxxxxxx> --- include/uapi/linux/perf_event.h | 3 ++- kernel/events/core.c | 21 +++++++++++++++++++++ 2 files changed, 23 insertions(+), 1 deletion(-) diff --git a/include/uapi/linux/perf_event.h b/include/uapi/linux/perf_event.h index ad15e40d7f5d..b9cc6829a40c 100644 --- a/include/uapi/linux/perf_event.h +++ b/include/uapi/linux/perf_event.h @@ -389,7 +389,8 @@ struct perf_event_attr { cgroup : 1, /* include cgroup events */ text_poke : 1, /* include text poke events */ build_id : 1, /* use build id in mmap2 events */ - __reserved_1 : 29; + sigtrap : 1, /* send synchronous SIGTRAP on event */ + __reserved_1 : 28; union { __u32 wakeup_events; /* wakeup every n events */ diff --git a/kernel/events/core.c b/kernel/events/core.c index 37a8297be164..8718763045fd 100644 --- a/kernel/events/core.c +++ b/kernel/events/core.c @@ -6288,6 +6288,17 @@ void perf_event_wakeup(struct perf_event *event) } } +static void perf_sigtrap(struct perf_event *event) +{ + struct kernel_siginfo info; + + clear_siginfo(&info); + info.si_signo = SIGTRAP; + info.si_code = TRAP_PERF; + info.si_errno = event->attr.type; + force_sig_info(&info); +} + static void perf_pending_event_disable(struct perf_event *event) { int cpu = READ_ONCE(event->pending_disable); @@ -6297,6 +6308,13 @@ static void perf_pending_event_disable(struct perf_event *event) if (cpu == smp_processor_id()) { WRITE_ONCE(event->pending_disable, -1); + + if (event->attr.sigtrap) { + atomic_inc(&event->event_limit); /* rearm event */ + perf_sigtrap(event); + return; + } + perf_event_disable_local(event); return; } @@ -11325,6 +11343,9 @@ perf_event_alloc(struct perf_event_attr *attr, int cpu, event->state = PERF_EVENT_STATE_INACTIVE; + if (event->attr.sigtrap) + atomic_set(&event->event_limit, 1); + if (task) { event->attach_state = PERF_ATTACH_TASK; /* -- 2.30.0.617.g56c4b15f3c-goog
