[PATCH v3 3/3] perf: core: Check sample_type in perf_sample_save_brstack

Yabin Cui
2024-05-10T00:24:52Z

Check sample_type in perf_sample_save_brstack() to prevent
saving branch stack data when it isn't required.

Suggested-by: Namhyung Kim <namhyung@kernel.org>
Signed-off-by: Yabin Cui <yabinc@google.com>
---
arch/x86/events/amd/core.c | 3 +--
arch/x86/events/core.c | 3 +--
arch/x86/events/intel/ds.c | 3 +--
include/linux/perf_event.h | 3 +++
4 files changed, 6 insertions(+), 6 deletions(-)

diff --git a/arch/x86/events/amd/core.c b/arch/x86/events/amd/core.c
index 985ef3b47919..fb9bf3aa1b42 100644
--- a/arch/x86/events/amd/core.c
+++ b/arch/x86/events/amd/core.c
@@ -967,8 +967,7 @@ static int amd_pmu_v2_handle_irq(struct pt_regs *regs)
if (!x86_perf_event_set_period(event))
continue;

- if (has_branch_stack(event))
- perf_sample_save_brstack(&data, event, &cpuc->lbr_stack, NULL);
+ perf_sample_save_brstack(&data, event, &cpuc->lbr_stack, NULL);

if (perf_event_overflow(event, &data, regs))
x86_pmu_stop(event, 0);
diff --git a/arch/x86/events/core.c b/arch/x86/events/core.c
index 5b0dd07b1ef1..ff5577315938 100644
--- a/arch/x86/events/core.c
+++ b/arch/x86/events/core.c
@@ -1702,8 +1702,7 @@ int x86_pmu_handle_irq(struct pt_regs *regs)

perf_sample_data_init(&data, 0, event->hw.last_period);

- if (has_branch_stack(event))
- perf_sample_save_brstack(&data, event, &cpuc->lbr_stack, NULL);
+ perf_sample_save_brstack(&data, event, &cpuc->lbr_stack, NULL);

if (perf_event_overflow(event, &data, regs))
x86_pmu_stop(event, 0);
diff --git a/arch/x86/events/intel/ds.c b/arch/x86/events/intel/ds.c
index c2b5585aa6d1..f25236ffa28f 100644
--- a/arch/x86/events/intel/ds.c
+++ b/arch/x86/events/intel/ds.c
@@ -1754,8 +1754,7 @@ static void setup_pebs_fixed_sample_data(struct perf_event *event,
if (x86_pmu.intel_cap.pebs_format >= 3)
setup_pebs_time(event, data, pebs->tsc);

- if (has_branch_stack(event))
- perf_sample_save_brstack(data, event, &cpuc->lbr_stack, NULL);
+ perf_sample_save_brstack(data, event, &cpuc->lbr_stack, NULL);
}

static void adaptive_pebs_save_regs(struct pt_regs *regs,
diff --git a/include/linux/perf_event.h b/include/linux/perf_event.h
index 8617815456b0..8cff96782446 100644
--- a/include/linux/perf_event.h
+++ b/include/linux/perf_event.h
@@ -1276,6 +1276,9 @@ static inline void perf_sample_save_brstack(struct perf_sample_data *data,
{
int size = sizeof(u64); /* nr */

+ if (!has_branch_stack(event))
+ return;
+
if (branch_sample_hw_index(event))
size += sizeof(u64);
size += brs->nr * sizeof(struct perf_branch_entry);
--
2.45.0.118.g7fe29c98d7-goog