From 8903461c9bc56fcb041fb92d054e2529951770b6 Mon Sep 17 00:00:00 2001 From: Michael Ellerman Date: Wed, 23 Jul 2014 17:20:04 +1000 Subject: [PATCH] powerpc/perf: Fix MMCR2 handling for EBB 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 Signed-off-by: Benjamin Herrenschmidt --- 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 */ -- 2.20.1