| From: Ravi Bangoria <ravi.bangoria@linux.ibm.com> |
| Date: Sat, 11 May 2019 08:12:17 +0530 |
| Subject: powerpc/perf: Fix MMCRA corruption by bhrb_filter |
| |
| 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)); |
| } |