3.16.75-rc1 review patch. If anyone has any objections, please let me know.
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From: Ravi Bangoria ravi.bangoria@linux.ibm.com
commit 3202e35ec1c8fc19cea24253ff83edf702a60a02 upstream.
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.
Fixes: 3925f46bb590 ("powerpc/perf: Enable branch stack sampling framework") Signed-off-by: Ravi Bangoria ravi.bangoria@linux.ibm.com Reviewed-by: Madhavan Srinivasan maddy@linux.vnet.ibm.com Signed-off-by: Michael Ellerman mpe@ellerman.id.au [bwh: Backported to 3.16: drop changes in power9-pmu.c] Signed-off-by: Ben Hutchings ben@decadent.org.uk --- --- a/arch/powerpc/perf/core-book3s.c +++ b/arch/powerpc/perf/core-book3s.c @@ -1726,6 +1726,7 @@ static int power_pmu_event_init(struct p int n; int err; struct cpu_hw_events *cpuhw; + u64 bhrb_filter;
if (!ppmu) return -ENOENT; @@ -1822,13 +1823,14 @@ static int power_pmu_event_init(struct p 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); --- a/arch/powerpc/perf/power8-pmu.c +++ b/arch/powerpc/perf/power8-pmu.c @@ -175,6 +175,7 @@ #define POWER8_MMCRA_IFM1 0x0000000040000000UL #define POWER8_MMCRA_IFM2 0x0000000080000000UL #define POWER8_MMCRA_IFM3 0x00000000C0000000UL +#define POWER8_MMCRA_BHRB_MASK 0x00000000C0000000UL
#define ONLY_PLM \ (PERF_SAMPLE_BRANCH_USER |\ @@ -666,6 +667,8 @@ static u64 power8_bhrb_filter_map(u64 br
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)); }