linux-kernel - [PATCH 1/3] perf: Use sample

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Date:   Thu,  8 Sep 2022 14:41:02 -0700
From:   Namhyung Kim <namhyung@...nel.org>
To:     Peter Zijlstra <peterz@...radead.org>,
        Alexei Starovoitov <ast@...nel.org>,
        Daniel Borkmann <daniel@...earbox.net>,
        Andrii Nakryiko <andrii@...nel.org>,
        Song Liu <songliubraving@...com>
Cc:     Ingo Molnar <mingo@...nel.org>,
        Mark Rutland <mark.rutland@....com>,
        Alexander Shishkin <alexander.shishkin@...ux.intel.com>,
        Arnaldo Carvalho de Melo <acme@...nel.org>,
        Jiri Olsa <jolsa@...nel.org>,
        LKML <linux-kernel@...r.kernel.org>,
        Martin KaFai Lau <kafai@...com>, Yonghong Song <yhs@...com>,
        John Fastabend <john.fastabend@...il.com>,
        KP Singh <kpsingh@...nel.org>, Hao Luo <haoluo@...gle.com>,
        Stanislav Fomichev <sdf@...gle.com>, bpf@...r.kernel.org,
        Kan Liang <kan.liang@...ux.intel.com>,
        Ravi Bangoria <ravi.bangoria@....com>
Subject: [PATCH 1/3] perf: Use sample_flags for callchain

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@...nel.org>
---
 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