linux-kernel - [PATCH] perf/x86: Fix missing sample size update on AMD BRS

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Message-ID: <20230427030527.580841-1-namhyung@kernel.org>
Date:   Wed, 26 Apr 2023 20:05:27 -0700
From:   Namhyung Kim <namhyung@...nel.org>
To:     Peter Zijlstra <peterz@...radead.org>,
        Ingo Molnar <mingo@...nel.org>
Cc:     Arnaldo Carvalho de Melo <acme@...nel.org>,
        Jiri Olsa <jolsa@...nel.org>, Ian Rogers <irogers@...gle.com>,
        Adrian Hunter <adrian.hunter@...el.com>,
        LKML <linux-kernel@...r.kernel.org>,
        Stephane Eranian <eranian@...gle.com>,
        Ravi Bangoria <ravi.bangoria@....com>,
        Sandipan Das <sandipan.das@....com>, stable@...r.kernel.org
Subject: [PATCH] perf/x86: Fix missing sample size update on AMD BRS

It missed to convert a PERF_SAMPLE_BRANCH_STACK user to call the new
perf_sample_save_brstack() helper in order to update the dyn_size.
This affects AMD Zen3 machines with the branch-brs event.

Fixes: eb55b455ef9c ("perf/core: Add perf_sample_save_brstack() helper")
Cc: stable@...r.kernel.org
Signed-off-by: Namhyung Kim <namhyung@...nel.org>
---
 arch/x86/events/core.c | 6 ++----
 1 file changed, 2 insertions(+), 4 deletions(-)

diff --git a/arch/x86/events/core.c b/arch/x86/events/core.c
index d096b04bf80e..9d248703cbdd 100644
--- a/arch/x86/events/core.c
+++ b/arch/x86/events/core.c
@@ -1703,10 +1703,8 @@ int x86_pmu_handle_irq(struct pt_regs *regs)
 
 		perf_sample_data_init(&data, 0, event->hw.last_period);
 
-		if (has_branch_stack(event)) {
-			data.br_stack = &cpuc->lbr_stack;
-			data.sample_flags |= PERF_SAMPLE_BRANCH_STACK;
-		}
+		if (has_branch_stack(event))
+			perf_sample_save_brstack(&data, event, &cpuc->lbr_stack);
 
 		if (perf_event_overflow(event, &data, regs))
 			x86_pmu_stop(event, 0);
-- 
2.40.1.495.gc816e09b53d-goog