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From: Breno Leitao <leitao@debian.org>
To: peterz@infradead.org, mingo@redhat.com, acme@kernel.org,
	jolsa@kernel.org, namhyung@kernel.org, sandipan.das@amd.com,
	thomas.lendacky@amd.com
Cc: linux-perf-users@vger.kernel.org, x86@kernel.org, leit@fb.com
Subject: [PATCH] perf/x86/amd/core: always clear status for idx
Date: Tue, 21 Mar 2023 04:33:38 -0700	[thread overview]
Message-ID: <20230321113338.1669660-1-leitao@debian.org> (raw)

The variable 'status' (which contains the unhandled overflow bits) is
not being properly masked in some cases, displaying the following
warning:

  WARNING: CPU: 156 PID: 475601 at arch/x86/events/amd/core.c:972 amd_pmu_v2_handle_irq+0x216/0x270

This seems to be happening because the loop is being continued before
the status bit being unset, in case x86_perf_event_set_period()
returns 0. This is also causing an inconsistency because the "handled"
counter is incremented, but the status bit is not cleaned.

Move the bit cleaning together above, together when the "handled"
counter is incremented.

Signed-off-by: Breno Leitao <leitao@debian.org>
---
 arch/x86/events/amd/core.c | 3 +--
 1 file changed, 1 insertion(+), 2 deletions(-)

diff --git a/arch/x86/events/amd/core.c b/arch/x86/events/amd/core.c
index 8c45b198b62f..bccea57dee81 100644
--- a/arch/x86/events/amd/core.c
+++ b/arch/x86/events/amd/core.c
@@ -923,6 +923,7 @@ static int amd_pmu_v2_handle_irq(struct pt_regs *regs)
 
 		/* Event overflow */
 		handled++;
+		status &= ~mask;
 		perf_sample_data_init(&data, 0, hwc->last_period);
 
 		if (!x86_perf_event_set_period(event))
@@ -933,8 +934,6 @@ static int amd_pmu_v2_handle_irq(struct pt_regs *regs)
 
 		if (perf_event_overflow(event, &data, regs))
 			x86_pmu_stop(event, 0);
-
-		status &= ~mask;
 	}
 
 	/*
-- 
2.34.1


             reply	other threads:[~2023-03-21 11:34 UTC|newest]

Thread overview: 5+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2023-03-21 11:33 Breno Leitao [this message]
2023-03-21 11:56 ` [PATCH] perf/x86/amd/core: always clear status for idx Sandipan Das
2023-03-21 12:42 ` Peter Zijlstra
2023-03-21 12:56   ` Sandipan Das
2023-03-21 13:43     ` Peter Zijlstra

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