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From: Sasha Levin <sashal@kernel.org>
To: linux-kernel@vger.kernel.org, stable@vger.kernel.org
Cc: Stephane Eranian <eranian@google.com>,
	Namhyung Kim <namhyung@kernel.org>,
	Peter Zijlstra <peterz@infradead.org>,
	Sasha Levin <sashal@kernel.org>
Subject: [PATCH AUTOSEL 5.9 21/23] perf/x86/intel: Check PEBS status correctly
Date: Sat, 12 Dec 2020 11:08:02 -0500	[thread overview]
Message-ID: <20201212160804.2334982-21-sashal@kernel.org> (raw)
In-Reply-To: <20201212160804.2334982-1-sashal@kernel.org>

From: Stephane Eranian <eranian@google.com>

[ Upstream commit fc17db8aa4c53cbd2d5469bb0521ea0f0a6dbb27 ]

The kernel cannot disambiguate when 2+ PEBS counters overflow at the
same time. This is what the comment for this code suggests.  However,
I see the comparison is done with the unfiltered p->status which is a
copy of IA32_PERF_GLOBAL_STATUS at the time of the sample. This
register contains more than the PEBS counter overflow bits. It also
includes many other bits which could also be set.

Signed-off-by: Namhyung Kim <namhyung@kernel.org>
Signed-off-by: Stephane Eranian <eranian@google.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Link: https://lkml.kernel.org/r/20201126110922.317681-2-namhyung@kernel.org
Signed-off-by: Sasha Levin <sashal@kernel.org>
---
 arch/x86/events/intel/ds.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/arch/x86/events/intel/ds.c b/arch/x86/events/intel/ds.c
index 404315df1e167..cf12e5a956f7e 100644
--- a/arch/x86/events/intel/ds.c
+++ b/arch/x86/events/intel/ds.c
@@ -1913,7 +1913,7 @@ static void intel_pmu_drain_pebs_nhm(struct pt_regs *iregs)
 		 * that caused the PEBS record. It's called collision.
 		 * If collision happened, the record will be dropped.
 		 */
-		if (p->status != (1ULL << bit)) {
+		if (pebs_status != (1ULL << bit)) {
 			for_each_set_bit(i, (unsigned long *)&pebs_status, size)
 				error[i]++;
 			continue;
-- 
2.27.0


  parent reply	other threads:[~2020-12-12 16:36 UTC|newest]

Thread overview: 28+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2020-12-12 16:07 [PATCH AUTOSEL 5.9 01/23] drm/tegra: sor: Don't warn on probe deferral Sasha Levin
2020-12-12 16:07 ` [PATCH AUTOSEL 5.9 02/23] drm/tegra: sor: Ensure regulators are disabled on teardown Sasha Levin
2020-12-12 16:07 ` [PATCH AUTOSEL 5.9 03/23] drm/tegra: replace idr_init() by idr_init_base() Sasha Levin
2020-12-12 16:07 ` [PATCH AUTOSEL 5.9 04/23] dm integrity: don't use drivers that have CRYPTO_ALG_ALLOCATES_MEMORY Sasha Levin
2020-12-12 16:07 ` [PATCH AUTOSEL 5.9 05/23] gfs2: set lockdep subclass for iopen glocks Sasha Levin
2020-12-12 16:07 ` [PATCH AUTOSEL 5.9 06/23] ASoC: rt5682: change SAR voltage threshold Sasha Levin
2020-12-12 16:07 ` [PATCH AUTOSEL 5.9 07/23] kernel/cpu: add arch override for clear_tasks_mm_cpumask() mm handling Sasha Levin
2020-12-12 16:07 ` [PATCH AUTOSEL 5.9 08/23] drm/tegra: sor: Disable clocks on error in tegra_sor_init() Sasha Levin
2020-12-12 16:07 ` [PATCH AUTOSEL 5.9 09/23] selftests: tc-testing: enable CONFIG_NET_SCH_RED as a module Sasha Levin
2020-12-12 16:07 ` [PATCH AUTOSEL 5.9 10/23] habanalabs: free host huge va_range if not used Sasha Levin
2020-12-12 16:07 ` [PATCH AUTOSEL 5.9 11/23] habanalabs: put devices before driver removal Sasha Levin
2020-12-12 16:07 ` [PATCH AUTOSEL 5.9 12/23] arm64: syscall: exit userspace before unmasking exceptions Sasha Levin
2020-12-12 16:07 ` [PATCH AUTOSEL 5.9 13/23] vxlan: Add needed_headroom for lower device Sasha Levin
2020-12-12 16:07 ` [PATCH AUTOSEL 5.9 14/23] vxlan: Copy needed_tailroom from lowerdev Sasha Levin
2020-12-12 16:07 ` [PATCH AUTOSEL 5.9 15/23] scsi: storvsc: Validate length of incoming packet in storvsc_on_channel_callback() Sasha Levin
2020-12-12 18:09   ` Andrea Parri
2020-12-13 14:05     ` Sasha Levin
2020-12-14 11:07     ` Dan Carpenter
2020-12-14 13:06       ` Konstantin Ryabitsev
2020-12-14 18:29         ` Sasha Levin
2020-12-12 16:07 ` [PATCH AUTOSEL 5.9 16/23] scsi: mpt3sas: Increase IOCInit request timeout to 30s Sasha Levin
2020-12-12 16:07 ` [PATCH AUTOSEL 5.9 17/23] dm table: Remove BUG_ON(in_interrupt()) Sasha Levin
2020-12-12 16:07 ` [PATCH AUTOSEL 5.9 18/23] iwlwifi: pcie: add one missing entry for AX210 Sasha Levin
2020-12-12 16:08 ` [PATCH AUTOSEL 5.9 19/23] iwlwifi: pcie: add some missing entries " Sasha Levin
2020-12-12 16:08 ` [PATCH AUTOSEL 5.9 20/23] drm/amd/display: Init clock value by current vbios CLKs Sasha Levin
2020-12-12 16:08 ` Sasha Levin [this message]
2020-12-12 16:08 ` [PATCH AUTOSEL 5.9 22/23] kbuild: avoid split lines in .mod files Sasha Levin
2020-12-12 16:08 ` [PATCH AUTOSEL 5.9 23/23] tools/testing/selftests/vm: fix build error Sasha Levin

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