3.16.75-rc1 review patch. If anyone has any objections, please let me know.
------------------ From: Ravi Bangoria <[email protected]> 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 <[email protected]> Reviewed-by: Madhavan Srinivasan <[email protected]> Signed-off-by: Michael Ellerman <[email protected]> [bwh: Backported to 3.16: drop changes in power9-pmu.c] Signed-off-by: Ben Hutchings <[email protected]> --- --- 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)); }
