From: Michael Ellerman <mpe@ellerman.id.au>
To: <linuxppc-dev@ozlabs.org>
Cc: Paul Mackerras <paulus@samba.org>, joel@jms.id.au
Subject: [PATCH] powerpc/perf: Fix MMCR2 handling for EBB
Date: Wed, 23 Jul 2014 17:20:04 +1000 [thread overview]
Message-ID: <1406100004-8776-1-git-send-email-mpe@ellerman.id.au> (raw)
In the recent commit b50a6c584bb4 "Clear MMCR2 when enabling PMU", I
screwed up the handling of MMCR2 for tasks using EBB.
We must make sure we set MMCR2 *before* ebb_switch_in(), otherwise we
overwrite the value of MMCR2 that userspace may have written. That
potentially breaks a task that uses EBB and manually uses MMCR2 for
event freezing.
Fixes: b50a6c584bb4 ("powerpc/perf: Clear MMCR2 when enabling PMU")
Cc: stable@vger.kernel.org
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
---
arch/powerpc/perf/core-book3s.c | 6 +++---
1 file changed, 3 insertions(+), 3 deletions(-)
diff --git a/arch/powerpc/perf/core-book3s.c b/arch/powerpc/perf/core-book3s.c
index 6b0641c3f03f..fe52db2eea6a 100644
--- a/arch/powerpc/perf/core-book3s.c
+++ b/arch/powerpc/perf/core-book3s.c
@@ -1307,6 +1307,9 @@ static void power_pmu_enable(struct pmu *pmu)
out_enable:
pmao_restore_workaround(ebb);
+ if (ppmu->flags & PPMU_ARCH_207S)
+ mtspr(SPRN_MMCR2, 0);
+
mmcr0 = ebb_switch_in(ebb, cpuhw->mmcr[0]);
mb();
@@ -1315,9 +1318,6 @@ static void power_pmu_enable(struct pmu *pmu)
write_mmcr0(cpuhw, mmcr0);
- if (ppmu->flags & PPMU_ARCH_207S)
- mtspr(SPRN_MMCR2, 0);
-
/*
* Enable instruction sampling if necessary
*/
--
1.9.1
reply other threads:[~2014-07-23 7:20 UTC|newest]
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