From: Marco Elver <elver@google.com>
To: elver@google.com, peterz@infradead.org,
alexander.shishkin@linux.intel.com, acme@kernel.org,
mingo@redhat.com, jolsa@redhat.com, mark.rutland@arm.com,
namhyung@kernel.org, tglx@linutronix.de
Cc: glider@google.com, viro@zeniv.linux.org.uk, arnd@arndb.de,
christian@brauner.io, dvyukov@google.com, jannh@google.com,
axboe@kernel.dk, mascasa@google.com, pcc@google.com,
irogers@google.com, kasan-dev@googlegroups.com,
linux-arch@vger.kernel.org, linux-fsdevel@vger.kernel.org,
linux-kernel@vger.kernel.org, linux-m68k@lists.linux-m68k.org,
x86@kernel.org
Subject: [PATCH RFC 3/4] perf/core: Add support for SIGTRAP on perf events
Date: Tue, 23 Feb 2021 15:34:25 +0100 [thread overview]
Message-ID: <20210223143426.2412737-4-elver@google.com> (raw)
In-Reply-To: <20210223143426.2412737-1-elver@google.com>
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@hirez.programming.kicks-ass.net/
Suggested-by: Peter Zijlstra <peterz@infradead.org>
Signed-off-by: Marco Elver <elver@google.com>
---
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
next prev parent reply other threads:[~2021-02-23 14:37 UTC|newest]
Thread overview: 17+ messages / expand[flat|nested] mbox.gz Atom feed top
2021-02-23 14:34 [PATCH RFC 0/4] Add support for synchronous signals on perf events Marco Elver
2021-02-23 14:34 ` [PATCH RFC 1/4] perf/core: Apply PERF_EVENT_IOC_MODIFY_ATTRIBUTES to children Marco Elver
2021-02-23 14:48 ` Dmitry Vyukov
2021-02-23 14:34 ` [PATCH RFC 2/4] signal: Introduce TRAP_PERF si_code and si_perf to siginfo Marco Elver
2021-02-23 18:01 ` Geert Uytterhoeven
2021-02-23 20:06 ` Arnd Bergmann
2021-02-23 14:34 ` Marco Elver [this message]
2021-02-23 14:57 ` [PATCH RFC 3/4] perf/core: Add support for SIGTRAP on perf events Dmitry Vyukov
2021-02-23 18:13 ` Dmitry Vyukov
2021-02-23 14:34 ` [PATCH RFC 4/4] perf/core: Add breakpoint information to siginfo on SIGTRAP Marco Elver
2021-02-23 15:01 ` Dmitry Vyukov
2021-02-23 15:10 ` Marco Elver
2021-02-23 15:16 ` Dmitry Vyukov
2021-02-23 17:16 ` Marco Elver
2021-02-23 20:03 ` [PATCH RFC 0/4] Add support for synchronous signals on perf events Marco Elver
2021-02-23 20:27 ` Andy Lutomirski
2021-02-23 22:26 ` Marco Elver
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