The following commit has been merged into the perf/core branch of tip:

Commit-ID:     faac6f105ef169e2e5678c14e1ffebf2a7d780b6
Gitweb:        https://git.kernel.org/tip/faac6f105ef169e2e5678c14e1ffebf2a7d780b6
Author:        Yabin Cui <yabinc@google.com>
AuthorDate:    Wed, 15 May 2024 12:36:09 -07:00
Committer:     Ingo Molnar <mingo@kernel.org>
CommitterDate: Tue, 19 Nov 2024 09:23:42 +01:00

perf/core: Check sample_type in perf_sample_save_brstack

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>
Signed-off-by: Ingo Molnar <mingo@kernel.org>
Reviewed-by: Ian Rogers <irogers@google.com>
Acked-by: Namhyung Kim <namhyung@kernel.org>
Link: https://lore.kernel.org/r/20240515193610.2350456-4-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 | 15 ++++++++++-----
 4 files changed, 13 insertions(+), 11 deletions(-)

diff --git a/arch/x86/events/amd/core.c b/arch/x86/events/amd/core.c
index b4a1a25..30d6ceb 100644
--- a/arch/x86/events/amd/core.c
+++ b/arch/x86/events/amd/core.c
@@ -1001,8 +1001,7 @@ 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 c75c482..8f218ac 100644
--- a/arch/x86/events/core.c
+++ b/arch/x86/events/core.c
@@ -1707,8 +1707,7 @@ 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 4990a24..acfd872 100644
--- a/arch/x86/events/intel/ds.c
+++ b/arch/x86/events/intel/ds.c
@@ -1888,8 +1888,7 @@ 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 3ac202d..bf831b1 100644
--- a/include/linux/perf_event.h
+++ b/include/linux/perf_event.h
@@ -1320,6 +1320,11 @@ static inline void perf_sample_save_raw_data(struct perf_sample_data *data,
 	data->sample_flags |= PERF_SAMPLE_RAW;
 }
 
+static inline bool has_branch_stack(struct perf_event *event)
+{
+	return event->attr.sample_type & PERF_SAMPLE_BRANCH_STACK;
+}
+
 static inline void perf_sample_save_brstack(struct perf_sample_data *data,
 					    struct perf_event *event,
 					    struct perf_branch_stack *brs,
@@ -1327,6 +1332,11 @@ static inline void perf_sample_save_brstack(struct perf_sample_data *data,
 {
 	int size = sizeof(u64); /* nr */
 
+	if (!has_branch_stack(event))
+		return;
+	if (WARN_ON_ONCE(data->sample_flags & PERF_SAMPLE_BRANCH_STACK))
+		return;
+
 	if (branch_sample_hw_index(event))
 		size += sizeof(u64);
 	size += brs->nr * sizeof(struct perf_branch_entry);
@@ -1716,11 +1726,6 @@ static inline unsigned long perf_arch_guest_misc_flags(struct pt_regs *regs)
 # define perf_arch_guest_misc_flags(regs)	perf_arch_guest_misc_flags(regs)
 #endif
 
-static inline bool has_branch_stack(struct perf_event *event)
-{
-	return event->attr.sample_type & PERF_SAMPLE_BRANCH_STACK;
-}
-
 static inline bool needs_branch_stack(struct perf_event *event)
 {
 	return event->attr.branch_sample_type != 0;