[PATCH 1/3] perf: Use sample_flags for callchain

From: Namhyung Kim
Date: Thu Sep 08 2022 - 17:41:14 EST


So that it can call perf_callchain() only if needed. Historically it used
__PERF_SAMPLE_CALLCHAIN_EARLY but we can do that with sample_flags in the
struct perf_sample_data.

Signed-off-by: Namhyung Kim <namhyung@xxxxxxxxxx>
---
arch/x86/events/amd/ibs.c | 4 +++-
arch/x86/events/intel/ds.c | 8 ++++++--
kernel/events/core.c | 2 +-
3 files changed, 10 insertions(+), 4 deletions(-)

diff --git a/arch/x86/events/amd/ibs.c b/arch/x86/events/amd/ibs.c
index c251bc44c088..dab094166693 100644
--- a/arch/x86/events/amd/ibs.c
+++ b/arch/x86/events/amd/ibs.c
@@ -798,8 +798,10 @@ static int perf_ibs_handle_irq(struct perf_ibs *perf_ibs, struct pt_regs *iregs)
* recorded as part of interrupt regs. Thus we need to use rip from
* interrupt regs while unwinding call stack.
*/
- if (event->attr.sample_type & PERF_SAMPLE_CALLCHAIN)
+ if (event->attr.sample_type & PERF_SAMPLE_CALLCHAIN) {
data.callchain = perf_callchain(event, iregs);
+ data.sample_flags |= PERF_SAMPLE_CALLCHAIN;
+ }

throttle = perf_event_overflow(event, &data, &regs);
out:
diff --git a/arch/x86/events/intel/ds.c b/arch/x86/events/intel/ds.c
index a5275c235c2a..4ba6ab6d0d92 100644
--- a/arch/x86/events/intel/ds.c
+++ b/arch/x86/events/intel/ds.c
@@ -1546,8 +1546,10 @@ static void setup_pebs_fixed_sample_data(struct perf_event *event,
* previous PMI context or an (I)RET happened between the record and
* PMI.
*/
- if (sample_type & PERF_SAMPLE_CALLCHAIN)
+ if (sample_type & PERF_SAMPLE_CALLCHAIN) {
data->callchain = perf_callchain(event, iregs);
+ data->sample_flags |= PERF_SAMPLE_CALLCHAIN;
+ }

/*
* We use the interrupt regs as a base because the PEBS record does not
@@ -1719,8 +1721,10 @@ static void setup_pebs_adaptive_sample_data(struct perf_event *event,
* previous PMI context or an (I)RET happened between the record and
* PMI.
*/
- if (sample_type & PERF_SAMPLE_CALLCHAIN)
+ if (sample_type & PERF_SAMPLE_CALLCHAIN) {
data->callchain = perf_callchain(event, iregs);
+ data->sample_flags |= PERF_SAMPLE_CALLCHAIN;
+ }

*regs = *iregs;
/* The ip in basic is EventingIP */
diff --git a/kernel/events/core.c b/kernel/events/core.c
index 15d27b14c827..b8af9fdbf26f 100644
--- a/kernel/events/core.c
+++ b/kernel/events/core.c
@@ -7323,7 +7323,7 @@ void perf_prepare_sample(struct perf_event_header *header,
if (sample_type & PERF_SAMPLE_CALLCHAIN) {
int size = 1;

- if (!(sample_type & __PERF_SAMPLE_CALLCHAIN_EARLY))
+ if (filtered_sample_type & PERF_SAMPLE_CALLCHAIN)
data->callchain = perf_callchain(event, regs);

size += data->callchain->nr;
--
2.37.2.789.g6183377224-goog