From: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
To: stable@vger.kernel.org
Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org>,
	patches@lists.linux.dev,
	Namhyung Kim <namhyung@kernel.org>,
	Yabin Cui <yabinc@google.com>,
	Ingo Molnar <mingo@kernel.org>,
	Ian Rogers <irogers@google.com>,
	Sasha Levin <sashal@kernel.org>
Subject: [PATCH 6.12 0771/1102] perf/core: Check sample_type in perf_sample_save_callchain
Date: Thu, 17 Sep 2026 16:11:54 +0100
Message-ID: <20260917151559.804931464@linuxfoundation.org>
In-Reply-To: <20260917151539.408551884@linuxfoundation.org>
References: <20260917151539.408551884@linuxfoundation.org>
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6.12-stable review patch.  If anyone has any objections, please let me know.

------------------

From: Yabin Cui <yabinc@google.com>

[ Upstream commit f226805bc5f60adf03783d8e4cbfe303ccecd64e ]

Check sample_type in perf_sample_save_callchain() to prevent
saving callchain 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/20240515193610.2350456-3-yabinc@google.com
Stable-dep-of: 88aa1223bfff ("perf/x86/intel: Correct pt_regs->flags update for PEBS path")
Signed-off-by: Sasha Levin <sashal@kernel.org>
---
 arch/x86/events/amd/ibs.c  | 3 +--
 arch/x86/events/intel/ds.c | 6 ++----
 include/linux/perf_event.h | 5 +++++
 3 files changed, 8 insertions(+), 6 deletions(-)

diff --git a/arch/x86/events/amd/ibs.c b/arch/x86/events/amd/ibs.c
index d34ee6f04f18f..1022d1dcbe447 100644
--- a/arch/x86/events/amd/ibs.c
+++ b/arch/x86/events/amd/ibs.c
@@ -1138,8 +1138,7 @@ 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)
-		perf_sample_save_callchain(&data, event, iregs);
+	perf_sample_save_callchain(&data, event, iregs);
 
 	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 d9e37ae5181f7..8a25b56a91dcf 100644
--- a/arch/x86/events/intel/ds.c
+++ b/arch/x86/events/intel/ds.c
@@ -1771,8 +1771,7 @@ 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)
-		perf_sample_save_callchain(data, event, iregs);
+	perf_sample_save_callchain(data, event, iregs);
 
 	/*
 	 * We use the interrupt regs as a base because the PEBS record does not
@@ -1939,8 +1938,7 @@ 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)
-		perf_sample_save_callchain(data, event, iregs);
+	perf_sample_save_callchain(data, event, iregs);
 
 	*regs = *iregs;
 	/* The ip in basic is EventingIP */
diff --git a/include/linux/perf_event.h b/include/linux/perf_event.h
index 79994d079e505..e0af9788e656e 100644
--- a/include/linux/perf_event.h
+++ b/include/linux/perf_event.h
@@ -1286,6 +1286,11 @@ static inline void perf_sample_save_callchain(struct perf_sample_data *data,
 {
 	int size = 1;
 
+	if (!(event->attr.sample_type & PERF_SAMPLE_CALLCHAIN))
+		return;
+	if (WARN_ON_ONCE(data->sample_flags & PERF_SAMPLE_CALLCHAIN))
+		return;
+
 	data->callchain = perf_callchain(event, regs);
 	size += data->callchain->nr;
 
-- 
2.53.0