powerpc/perf: Freeze PMC5/6 if we're not using them
On Power8 we can freeze PMC5 and 6 if we're not using them. Normally they
run all the time.
As noticed by Anshuman, we should unfreeze them when we disable the PMU
as there are legacy tools which expect them to run all the time.
Signed-off-by: Michael Ellerman <michael@ellerman.id.au>
CC: <stable@vger.kernel.org> [v3.10]
Signed-off-by: Benjamin Herrenschmidt <benh@kernel.crashing.org>
diff --git a/arch/powerpc/perf/core-book3s.c b/arch/powerpc/perf/core-book3s.c
index 5d502bf..517a135 100644
--- a/arch/powerpc/perf/core-book3s.c
+++ b/arch/powerpc/perf/core-book3s.c
@@ -75,6 +75,7 @@
#define MMCR0_FCHV 0
#define MMCR0_PMCjCE MMCR0_PMCnCE
+#define MMCR0_FC56 0
#define MMCR0_PMAO 0
#define SPRN_MMCRA SPRN_MMCR2
@@ -870,11 +871,11 @@
}
/*
- * Set the 'freeze counters' bit, clear PMAO.
+ * Set the 'freeze counters' bit, clear PMAO/FC56.
*/
val = mfspr(SPRN_MMCR0);
val |= MMCR0_FC;
- val &= ~MMCR0_PMAO;
+ val &= ~(MMCR0_PMAO | MMCR0_FC56);
/*
* The barrier is to make sure the mtspr has been