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Commit 3202e35e authored by Ravi Bangoria's avatar Ravi Bangoria Committed by Michael Ellerman
Browse files

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: 3925f46b ("powerpc/perf: Enable branch stack sampling framework")
Cc: stable@vger.kernel.org # v3.10+
Signed-off-by: default avatarRavi Bangoria <ravi.bangoria@linux.ibm.com>
Reviewed-by: default avatarMadhavan Srinivasan <maddy@linux.vnet.ibm.com>
Signed-off-by: default avatarMichael Ellerman <mpe@ellerman.id.au>
parent b59bd352

arch/powerpc/perf/core-book3s.c

+4 −2
Original line number Original line Diff line number Diff line
@@ -1850,6 +1850,7 @@ static int power_pmu_event_init(struct perf_event *event) 
	int n;

	int n;

	int err;

	int err;

	struct cpu_hw_events *cpuhw;

	struct cpu_hw_events *cpuhw;

	u64 bhrb_filter;





	if (!ppmu)

	if (!ppmu)

		return -ENOENT;

		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);

	err = power_check_constraints(cpuhw, events, cflags, n + 1);





	if (has_branch_stack(event)) {

	if (has_branch_stack(event)) {

		cpuhw->bhrb_filter = ppmu->bhrb_filter_map(

		bhrb_filter = ppmu->bhrb_filter_map(

					event->attr.branch_sample_type);

					event->attr.branch_sample_type);





		if (cpuhw->bhrb_filter == -1) {

		if (bhrb_filter == -1) {

			put_cpu_var(cpu_hw_events);

			put_cpu_var(cpu_hw_events);

			return -EOPNOTSUPP;

			return -EOPNOTSUPP;

		}

		}

		cpuhw->bhrb_filter = bhrb_filter;

	}

	}





	put_cpu_var(cpu_hw_events);

	put_cpu_var(cpu_hw_events);

arch/powerpc/perf/power8-pmu.c

+3 −0
Original line number Original line Diff line number Diff line
@@ -29,6 +29,7 @@ enum { 
#define	POWER8_MMCRA_IFM1		0x0000000040000000UL

#define	POWER8_MMCRA_IFM1		0x0000000040000000UL

#define	POWER8_MMCRA_IFM2		0x0000000080000000UL

#define	POWER8_MMCRA_IFM2		0x0000000080000000UL

#define	POWER8_MMCRA_IFM3		0x00000000C0000000UL

#define	POWER8_MMCRA_IFM3		0x00000000C0000000UL

#define	POWER8_MMCRA_BHRB_MASK		0x00000000C0000000UL





/*

/*

 * Raw event encoding for PowerISA v2.07 (Power8):

 * 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)

static void power8_config_bhrb(u64 pmu_bhrb_filter)

{

{

	pmu_bhrb_filter &= POWER8_MMCRA_BHRB_MASK;



	/* Enable BHRB filter in PMU */

	/* Enable BHRB filter in PMU */

	mtspr(SPRN_MMCRA, (mfspr(SPRN_MMCRA) | pmu_bhrb_filter));

	mtspr(SPRN_MMCRA, (mfspr(SPRN_MMCRA) | pmu_bhrb_filter));

}

}

arch/powerpc/perf/power9-pmu.c

+3 −0
Original line number Original line Diff line number Diff line
@@ -92,6 +92,7 @@ enum { 
#define POWER9_MMCRA_IFM1		0x0000000040000000UL

#define POWER9_MMCRA_IFM1		0x0000000040000000UL

#define POWER9_MMCRA_IFM2		0x0000000080000000UL

#define POWER9_MMCRA_IFM2		0x0000000080000000UL

#define POWER9_MMCRA_IFM3		0x00000000C0000000UL

#define POWER9_MMCRA_IFM3		0x00000000C0000000UL

#define POWER9_MMCRA_BHRB_MASK		0x00000000C0000000UL





/* Nasty Power9 specific hack */

/* Nasty Power9 specific hack */

#define PVR_POWER9_CUMULUS		0x00002000

#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)

static void power9_config_bhrb(u64 pmu_bhrb_filter)

{

{

	pmu_bhrb_filter &= POWER9_MMCRA_BHRB_MASK;



	/* Enable BHRB filter in PMU */

	/* Enable BHRB filter in PMU */

	mtspr(SPRN_MMCRA, (mfspr(SPRN_MMCRA) | pmu_bhrb_filter));

	mtspr(SPRN_MMCRA, (mfspr(SPRN_MMCRA) | pmu_bhrb_filter));

}

}