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authorPeter Zijlstra <peterz@infradead.org>2020-10-30 15:50:32 +0100
committerPeter Zijlstra <peterz@infradead.org>2020-11-09 18:12:33 +0100
commit267fb27352b6fc9fdbad753127a239f75618ecbc (patch)
tree2f99dd2dedf21e53d329e16cdb615e2c234202bb /kernel
parent7bdb157cdebbf95a1cd94ed2e01b338714075d00 (diff)
downloadlinux-267fb27352b6fc9fdbad753127a239f75618ecbc.tar.bz2
perf: Reduce stack usage of perf_output_begin()
__perf_output_begin() has an on-stack struct perf_sample_data in the unlikely case it needs to generate a LOST record. However, every call to perf_output_begin() must already have a perf_sample_data on-stack. Reported-by: Thomas Gleixner <tglx@linutronix.de> Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org> Link: https://lkml.kernel.org/r/20201030151954.985416146@infradead.org
Diffstat (limited to 'kernel')
-rw-r--r--kernel/events/core.c32
-rw-r--r--kernel/events/ring_buffer.c20
2 files changed, 28 insertions, 24 deletions
diff --git a/kernel/events/core.c b/kernel/events/core.c
index 5a29ab09e72d..fc681c7c1e03 100644
--- a/kernel/events/core.c
+++ b/kernel/events/core.c
@@ -7186,6 +7186,7 @@ __perf_event_output(struct perf_event *event,
struct perf_sample_data *data,
struct pt_regs *regs,
int (*output_begin)(struct perf_output_handle *,
+ struct perf_sample_data *,
struct perf_event *,
unsigned int))
{
@@ -7198,7 +7199,7 @@ __perf_event_output(struct perf_event *event,
perf_prepare_sample(&header, data, event, regs);
- err = output_begin(&handle, event, header.size);
+ err = output_begin(&handle, data, event, header.size);
if (err)
goto exit;
@@ -7264,7 +7265,7 @@ perf_event_read_event(struct perf_event *event,
int ret;
perf_event_header__init_id(&read_event.header, &sample, event);
- ret = perf_output_begin(&handle, event, read_event.header.size);
+ ret = perf_output_begin(&handle, &sample, event, read_event.header.size);
if (ret)
return;
@@ -7533,7 +7534,7 @@ static void perf_event_task_output(struct perf_event *event,
perf_event_header__init_id(&task_event->event_id.header, &sample, event);
- ret = perf_output_begin(&handle, event,
+ ret = perf_output_begin(&handle, &sample, event,
task_event->event_id.header.size);
if (ret)
goto out;
@@ -7636,7 +7637,7 @@ static void perf_event_comm_output(struct perf_event *event,
return;
perf_event_header__init_id(&comm_event->event_id.header, &sample, event);
- ret = perf_output_begin(&handle, event,
+ ret = perf_output_begin(&handle, &sample, event,
comm_event->event_id.header.size);
if (ret)
@@ -7736,7 +7737,7 @@ static void perf_event_namespaces_output(struct perf_event *event,
perf_event_header__init_id(&namespaces_event->event_id.header,
&sample, event);
- ret = perf_output_begin(&handle, event,
+ ret = perf_output_begin(&handle, &sample, event,
namespaces_event->event_id.header.size);
if (ret)
goto out;
@@ -7863,7 +7864,7 @@ static void perf_event_cgroup_output(struct perf_event *event, void *data)
perf_event_header__init_id(&cgroup_event->event_id.header,
&sample, event);
- ret = perf_output_begin(&handle, event,
+ ret = perf_output_begin(&handle, &sample, event,
cgroup_event->event_id.header.size);
if (ret)
goto out;
@@ -7989,7 +7990,7 @@ static void perf_event_mmap_output(struct perf_event *event,
}
perf_event_header__init_id(&mmap_event->event_id.header, &sample, event);
- ret = perf_output_begin(&handle, event,
+ ret = perf_output_begin(&handle, &sample, event,
mmap_event->event_id.header.size);
if (ret)
goto out;
@@ -8299,7 +8300,7 @@ void perf_event_aux_event(struct perf_event *event, unsigned long head,
int ret;
perf_event_header__init_id(&rec.header, &sample, event);
- ret = perf_output_begin(&handle, event, rec.header.size);
+ ret = perf_output_begin(&handle, &sample, event, rec.header.size);
if (ret)
return;
@@ -8333,7 +8334,7 @@ void perf_log_lost_samples(struct perf_event *event, u64 lost)
perf_event_header__init_id(&lost_samples_event.header, &sample, event);
- ret = perf_output_begin(&handle, event,
+ ret = perf_output_begin(&handle, &sample, event,
lost_samples_event.header.size);
if (ret)
return;
@@ -8388,7 +8389,7 @@ static void perf_event_switch_output(struct perf_event *event, void *data)
perf_event_header__init_id(&se->event_id.header, &sample, event);
- ret = perf_output_begin(&handle, event, se->event_id.header.size);
+ ret = perf_output_begin(&handle, &sample, event, se->event_id.header.size);
if (ret)
return;
@@ -8463,7 +8464,7 @@ static void perf_log_throttle(struct perf_event *event, int enable)
perf_event_header__init_id(&throttle_event.header, &sample, event);
- ret = perf_output_begin(&handle, event,
+ ret = perf_output_begin(&handle, &sample, event,
throttle_event.header.size);
if (ret)
return;
@@ -8506,7 +8507,7 @@ static void perf_event_ksymbol_output(struct perf_event *event, void *data)
perf_event_header__init_id(&ksymbol_event->event_id.header,
&sample, event);
- ret = perf_output_begin(&handle, event,
+ ret = perf_output_begin(&handle, &sample, event,
ksymbol_event->event_id.header.size);
if (ret)
return;
@@ -8596,7 +8597,7 @@ static void perf_event_bpf_output(struct perf_event *event, void *data)
perf_event_header__init_id(&bpf_event->event_id.header,
&sample, event);
- ret = perf_output_begin(&handle, event,
+ ret = perf_output_begin(&handle, data, event,
bpf_event->event_id.header.size);
if (ret)
return;
@@ -8705,7 +8706,8 @@ static void perf_event_text_poke_output(struct perf_event *event, void *data)
perf_event_header__init_id(&text_poke_event->event_id.header, &sample, event);
- ret = perf_output_begin(&handle, event, text_poke_event->event_id.header.size);
+ ret = perf_output_begin(&handle, &sample, event,
+ text_poke_event->event_id.header.size);
if (ret)
return;
@@ -8786,7 +8788,7 @@ static void perf_log_itrace_start(struct perf_event *event)
rec.tid = perf_event_tid(event, current);
perf_event_header__init_id(&rec.header, &sample, event);
- ret = perf_output_begin(&handle, event, rec.header.size);
+ ret = perf_output_begin(&handle, &sample, event, rec.header.size);
if (ret)
return;
diff --git a/kernel/events/ring_buffer.c b/kernel/events/ring_buffer.c
index 192b8abc6330..ef91ae75ca56 100644
--- a/kernel/events/ring_buffer.c
+++ b/kernel/events/ring_buffer.c
@@ -147,6 +147,7 @@ ring_buffer_has_space(unsigned long head, unsigned long tail,
static __always_inline int
__perf_output_begin(struct perf_output_handle *handle,
+ struct perf_sample_data *data,
struct perf_event *event, unsigned int size,
bool backward)
{
@@ -237,18 +238,16 @@ __perf_output_begin(struct perf_output_handle *handle,
handle->size = (1UL << page_shift) - offset;
if (unlikely(have_lost)) {
- struct perf_sample_data sample_data;
-
lost_event.header.size = sizeof(lost_event);
lost_event.header.type = PERF_RECORD_LOST;
lost_event.header.misc = 0;
lost_event.id = event->id;
lost_event.lost = local_xchg(&rb->lost, 0);
- perf_event_header__init_id(&lost_event.header,
- &sample_data, event);
+ /* XXX mostly redundant; @data is already fully initializes */
+ perf_event_header__init_id(&lost_event.header, data, event);
perf_output_put(handle, lost_event);
- perf_event__output_id_sample(event, handle, &sample_data);
+ perf_event__output_id_sample(event, handle, data);
}
return 0;
@@ -263,22 +262,25 @@ out:
}
int perf_output_begin_forward(struct perf_output_handle *handle,
- struct perf_event *event, unsigned int size)
+ struct perf_sample_data *data,
+ struct perf_event *event, unsigned int size)
{
- return __perf_output_begin(handle, event, size, false);
+ return __perf_output_begin(handle, data, event, size, false);
}
int perf_output_begin_backward(struct perf_output_handle *handle,
+ struct perf_sample_data *data,
struct perf_event *event, unsigned int size)
{
- return __perf_output_begin(handle, event, size, true);
+ return __perf_output_begin(handle, data, event, size, true);
}
int perf_output_begin(struct perf_output_handle *handle,
+ struct perf_sample_data *data,
struct perf_event *event, unsigned int size)
{
- return __perf_output_begin(handle, event, size,
+ return __perf_output_begin(handle, data, event, size,
unlikely(is_write_backward(event)));
}