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powerpc/perf: Fix MMCRA corruption by bhrb_filter 

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: 3925f46bb5 ("powerpc/perf: Enable branch stack sampling framework")
Cc: stable@vger.kernel.org # v3.10+
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>
This commit is contained in:
Ravi Bangoria 2019-05-11 08:12:17 +05:30 committed by Michael Ellerman
parent b59bd3527f
commit 3202e35ec1
3 changed files with 10 additions and 2 deletions
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6
arch/powerpc/perf/core-book3s.c
View File

@ -1850,6 +1850,7 @@ 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;
@ -1955,13 +1956,14 @@ 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);

3
arch/powerpc/perf/power8-pmu.c
View File

@ -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));
}

3
arch/powerpc/perf/power9-pmu.c
View File

@ -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));
}