| Message ID | 20230531040428.501523-4-anshuman.khandual@arm.com (mailing list archive) |
|---|---|
| State | New, archived |
| Headers | show |
| Series | arm64/perf: Enable branch stack sampling | expand |
On Wed, May 31, 2023 at 09:34:21AM +0530, Anshuman Khandual wrote: > This updates 'struct arm_pmu' for branch stack sampling support later. This > adds a new 'features' element in the structure to track supported features, > and another 'private' element to encapsulate implementation attributes on a > given 'struct arm_pmu'. These updates here will help in tracking any branch > stack sampling support, which is being added later. This also adds a helper > arm_pmu_branch_stack_supported(). > > This also enables perf branch stack sampling event on all 'struct arm pmu', > supporting the feature but after removing the current gate that blocks such > events unconditionally in armpmu_event_init(). Instead a quick probe can be > initiated via arm_pmu_branch_stack_supported() to ascertain the support. > > Cc: Catalin Marinas <catalin.marinas@arm.com> > Cc: Will Deacon <will@kernel.org> > Cc: Mark Rutland <mark.rutland@arm.com> > Cc: linux-arm-kernel@lists.infradead.org > Cc: linux-kernel@vger.kernel.org > Tested-by: James Clark <james.clark@arm.com> > Signed-off-by: Anshuman Khandual <anshuman.khandual@arm.com> > --- > drivers/perf/arm_pmu.c | 3 +-- > include/linux/perf/arm_pmu.h | 12 +++++++++++- > 2 files changed, 12 insertions(+), 3 deletions(-) > > diff --git a/drivers/perf/arm_pmu.c b/drivers/perf/arm_pmu.c > index aada47e3b126..d4a4f2bd89a5 100644 > --- a/drivers/perf/arm_pmu.c > +++ b/drivers/perf/arm_pmu.c > @@ -510,8 +510,7 @@ static int armpmu_event_init(struct perf_event *event) > !cpumask_test_cpu(event->cpu, &armpmu->supported_cpus)) > return -ENOENT; > > - /* does not support taken branch sampling */ > - if (has_branch_stack(event)) > + if (has_branch_stack(event) && !arm_pmu_branch_stack_supported(armpmu)) > return -EOPNOTSUPP; > > return __hw_perf_event_init(event); > diff --git a/include/linux/perf/arm_pmu.h b/include/linux/perf/arm_pmu.h > index f7fbd162ca4c..0da745eaf426 100644 > --- a/include/linux/perf/arm_pmu.h > +++ b/include/linux/perf/arm_pmu.h > @@ -102,7 +102,9 @@ struct arm_pmu { > int (*map_event)(struct perf_event *event); > void (*sched_task)(struct perf_event_pmu_context *pmu_ctx, bool sched_in); > int num_events; > - bool secure_access; /* 32-bit ARM only */ > + unsigned int secure_access : 1, /* 32-bit ARM only */ > + has_branch_stack: 1, /* 64-bit ARM only */ > + reserved : 30; > #define ARMV8_PMUV3_MAX_COMMON_EVENTS 0x40 > DECLARE_BITMAP(pmceid_bitmap, ARMV8_PMUV3_MAX_COMMON_EVENTS); > #define ARMV8_PMUV3_EXT_COMMON_EVENT_BASE 0x4000 > @@ -118,8 +120,16 @@ struct arm_pmu { > > /* Only to be used by ACPI probing code */ > unsigned long acpi_cpuid; > + > + /* Implementation specific attributes */ > + void *private; > }; > > +static inline bool arm_pmu_branch_stack_supported(struct arm_pmu *armpmu) > +{ > + return armpmu->has_branch_stack; > +} Since this is a trivial test, and we already access the 'secure_access' field directly, I'd prefer we removed this helper and directly accessesed arm_pmu::has_branch_stack, e.g. with the logic in armpmu_event_init() being: if (has_branch_stack(event) && !armpmu->has_branch_stack) return -EOPNOTSUPP; With that: Acked-by: Mark Rutland <mark.rutland@arm.com> Mark.
On 6/5/23 13:28, Mark Rutland wrote: > On Wed, May 31, 2023 at 09:34:21AM +0530, Anshuman Khandual wrote: >> This updates 'struct arm_pmu' for branch stack sampling support later. This >> adds a new 'features' element in the structure to track supported features, >> and another 'private' element to encapsulate implementation attributes on a >> given 'struct arm_pmu'. These updates here will help in tracking any branch >> stack sampling support, which is being added later. This also adds a helper >> arm_pmu_branch_stack_supported(). >> >> This also enables perf branch stack sampling event on all 'struct arm pmu', >> supporting the feature but after removing the current gate that blocks such >> events unconditionally in armpmu_event_init(). Instead a quick probe can be >> initiated via arm_pmu_branch_stack_supported() to ascertain the support. >> >> Cc: Catalin Marinas <catalin.marinas@arm.com> >> Cc: Will Deacon <will@kernel.org> >> Cc: Mark Rutland <mark.rutland@arm.com> >> Cc: linux-arm-kernel@lists.infradead.org >> Cc: linux-kernel@vger.kernel.org >> Tested-by: James Clark <james.clark@arm.com> >> Signed-off-by: Anshuman Khandual <anshuman.khandual@arm.com> >> --- >> drivers/perf/arm_pmu.c | 3 +-- >> include/linux/perf/arm_pmu.h | 12 +++++++++++- >> 2 files changed, 12 insertions(+), 3 deletions(-) >> >> diff --git a/drivers/perf/arm_pmu.c b/drivers/perf/arm_pmu.c >> index aada47e3b126..d4a4f2bd89a5 100644 >> --- a/drivers/perf/arm_pmu.c >> +++ b/drivers/perf/arm_pmu.c >> @@ -510,8 +510,7 @@ static int armpmu_event_init(struct perf_event *event) >> !cpumask_test_cpu(event->cpu, &armpmu->supported_cpus)) >> return -ENOENT; >> >> - /* does not support taken branch sampling */ >> - if (has_branch_stack(event)) >> + if (has_branch_stack(event) && !arm_pmu_branch_stack_supported(armpmu)) >> return -EOPNOTSUPP; >> >> return __hw_perf_event_init(event); >> diff --git a/include/linux/perf/arm_pmu.h b/include/linux/perf/arm_pmu.h >> index f7fbd162ca4c..0da745eaf426 100644 >> --- a/include/linux/perf/arm_pmu.h >> +++ b/include/linux/perf/arm_pmu.h >> @@ -102,7 +102,9 @@ struct arm_pmu { >> int (*map_event)(struct perf_event *event); >> void (*sched_task)(struct perf_event_pmu_context *pmu_ctx, bool sched_in); >> int num_events; >> - bool secure_access; /* 32-bit ARM only */ >> + unsigned int secure_access : 1, /* 32-bit ARM only */ >> + has_branch_stack: 1, /* 64-bit ARM only */ >> + reserved : 30; >> #define ARMV8_PMUV3_MAX_COMMON_EVENTS 0x40 >> DECLARE_BITMAP(pmceid_bitmap, ARMV8_PMUV3_MAX_COMMON_EVENTS); >> #define ARMV8_PMUV3_EXT_COMMON_EVENT_BASE 0x4000 >> @@ -118,8 +120,16 @@ struct arm_pmu { >> >> /* Only to be used by ACPI probing code */ >> unsigned long acpi_cpuid; >> + >> + /* Implementation specific attributes */ >> + void *private; >> }; >> >> +static inline bool arm_pmu_branch_stack_supported(struct arm_pmu *armpmu) >> +{ >> + return armpmu->has_branch_stack; >> +} > > Since this is a trivial test, and we already access the 'secure_access' field > directly, I'd prefer we removed this helper and directly accessesed > arm_pmu::has_branch_stack, e.g. with the logic in armpmu_event_init() being: > > if (has_branch_stack(event) && !armpmu->has_branch_stack) > return -EOPNOTSUPP; Sure, will drop the helper and change as suggested in all the call sites. > > With that: > > Acked-by: Mark Rutland <mark.rutland@arm.com> > > Mark.
diff --git a/drivers/perf/arm_pmu.c b/drivers/perf/arm_pmu.c index aada47e3b126..d4a4f2bd89a5 100644 --- a/drivers/perf/arm_pmu.c +++ b/drivers/perf/arm_pmu.c @@ -510,8 +510,7 @@ static int armpmu_event_init(struct perf_event *event) !cpumask_test_cpu(event->cpu, &armpmu->supported_cpus)) return -ENOENT; - /* does not support taken branch sampling */ - if (has_branch_stack(event)) + if (has_branch_stack(event) && !arm_pmu_branch_stack_supported(armpmu)) return -EOPNOTSUPP; return __hw_perf_event_init(event); diff --git a/include/linux/perf/arm_pmu.h b/include/linux/perf/arm_pmu.h index f7fbd162ca4c..0da745eaf426 100644 --- a/include/linux/perf/arm_pmu.h +++ b/include/linux/perf/arm_pmu.h @@ -102,7 +102,9 @@ struct arm_pmu { int (*map_event)(struct perf_event *event); void (*sched_task)(struct perf_event_pmu_context *pmu_ctx, bool sched_in); int num_events; - bool secure_access; /* 32-bit ARM only */ + unsigned int secure_access : 1, /* 32-bit ARM only */ + has_branch_stack: 1, /* 64-bit ARM only */ + reserved : 30; #define ARMV8_PMUV3_MAX_COMMON_EVENTS 0x40 DECLARE_BITMAP(pmceid_bitmap, ARMV8_PMUV3_MAX_COMMON_EVENTS); #define ARMV8_PMUV3_EXT_COMMON_EVENT_BASE 0x4000 @@ -118,8 +120,16 @@ struct arm_pmu { /* Only to be used by ACPI probing code */ unsigned long acpi_cpuid; + + /* Implementation specific attributes */ + void *private; }; +static inline bool arm_pmu_branch_stack_supported(struct arm_pmu *armpmu) +{ + return armpmu->has_branch_stack; +} + #define to_arm_pmu(p) (container_of(p, struct arm_pmu, pmu)) u64 armpmu_event_update(struct perf_event *event);