Messages in this thread | | | Subject | Re: [PATCH 2/2] powerpc/perf: Fix mmcra corruption by bhrb_filter | From | Madhavan Srinivasan <> | Date | Wed, 22 May 2019 10:31:35 +0530 |
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On 11/05/19 8:12 AM, Ravi Bangoria wrote: > Consider a scenario where user creates two events: > > 1st event: > attr.sample_type |= PERF_SAMPLE_BRANCH_STACK; > attr.branch_sample_type = PERF_SAMPLE_BRANCH_ANY; > fd = perf_event_open(attr, 0, 1, -1, 0); > > This sets cpuhw->bhrb_filter to 0 and returns valid fd. > > 2nd event: > attr.sample_type |= PERF_SAMPLE_BRANCH_STACK; > attr.branch_sample_type = PERF_SAMPLE_BRANCH_CALL; > fd = perf_event_open(attr, 0, 1, -1, 0); > > It overrides cpuhw->bhrb_filter to -1 and returns with error. > > Now if power_pmu_enable() gets called by any path other than > power_pmu_add(), ppmu->config_bhrb(-1) will set mmcra to -1.
Reviewed-by: Madhavan Srinivasan <maddy@linux.vnet.ibm.com>
> Signed-off-by: Ravi Bangoria <ravi.bangoria@linux.ibm.com> > --- > arch/powerpc/perf/core-book3s.c | 6 ++++-- > arch/powerpc/perf/power8-pmu.c | 3 +++ > arch/powerpc/perf/power9-pmu.c | 3 +++ > 3 files changed, 10 insertions(+), 2 deletions(-) > > diff --git a/arch/powerpc/perf/core-book3s.c b/arch/powerpc/perf/core-book3s.c > index b0723002a396..8eb5dc5df62b 100644 > --- a/arch/powerpc/perf/core-book3s.c > +++ b/arch/powerpc/perf/core-book3s.c > @@ -1846,6 +1846,7 @@ static int power_pmu_event_init(struct perf_event *event) > int n; > int err; > struct cpu_hw_events *cpuhw; > + u64 bhrb_filter; > > if (!ppmu) > return -ENOENT; > @@ -1951,13 +1952,14 @@ static int power_pmu_event_init(struct perf_event *event) > err = power_check_constraints(cpuhw, events, cflags, n + 1); > > if (has_branch_stack(event)) { > - cpuhw->bhrb_filter = ppmu->bhrb_filter_map( > + bhrb_filter = ppmu->bhrb_filter_map( > event->attr.branch_sample_type); > > - if (cpuhw->bhrb_filter == -1) { > + if (bhrb_filter == -1) { > put_cpu_var(cpu_hw_events); > return -EOPNOTSUPP; > } > + cpuhw->bhrb_filter = bhrb_filter; > } > > put_cpu_var(cpu_hw_events); > diff --git a/arch/powerpc/perf/power8-pmu.c b/arch/powerpc/perf/power8-pmu.c > index d12a2db26353..d10feef93b6b 100644 > --- a/arch/powerpc/perf/power8-pmu.c > +++ b/arch/powerpc/perf/power8-pmu.c > @@ -29,6 +29,7 @@ enum { > #define POWER8_MMCRA_IFM1 0x0000000040000000UL > #define POWER8_MMCRA_IFM2 0x0000000080000000UL > #define POWER8_MMCRA_IFM3 0x00000000C0000000UL > +#define POWER8_MMCRA_BHRB_MASK 0x00000000C0000000UL > > /* > * Raw event encoding for PowerISA v2.07 (Power8): > @@ -243,6 +244,8 @@ static u64 power8_bhrb_filter_map(u64 branch_sample_type) > > static void power8_config_bhrb(u64 pmu_bhrb_filter) > { > + pmu_bhrb_filter &= POWER8_MMCRA_BHRB_MASK; > + > /* Enable BHRB filter in PMU */ > mtspr(SPRN_MMCRA, (mfspr(SPRN_MMCRA) | pmu_bhrb_filter)); > } > diff --git a/arch/powerpc/perf/power9-pmu.c b/arch/powerpc/perf/power9-pmu.c > index 030544e35959..f3987915cadc 100644 > --- a/arch/powerpc/perf/power9-pmu.c > +++ b/arch/powerpc/perf/power9-pmu.c > @@ -92,6 +92,7 @@ enum { > #define POWER9_MMCRA_IFM1 0x0000000040000000UL > #define POWER9_MMCRA_IFM2 0x0000000080000000UL > #define POWER9_MMCRA_IFM3 0x00000000C0000000UL > +#define POWER9_MMCRA_BHRB_MASK 0x00000000C0000000UL > > /* Nasty Power9 specific hack */ > #define PVR_POWER9_CUMULUS 0x00002000 > @@ -300,6 +301,8 @@ static u64 power9_bhrb_filter_map(u64 branch_sample_type) > > static void power9_config_bhrb(u64 pmu_bhrb_filter) > { > + pmu_bhrb_filter &= POWER9_MMCRA_BHRB_MASK; > + > /* Enable BHRB filter in PMU */ > mtspr(SPRN_MMCRA, (mfspr(SPRN_MMCRA) | pmu_bhrb_filter)); > }
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