perf: Use sample_flags for branch stack

Use the new sample_flags to indicate whether the branch stack is filled
by the PMU driver.

Remove the br_stack from the perf_sample_data_init() to minimize the number
of cache lines touched.

Signed-off-by: Kan Liang <kan.liang@linux.intel.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Link: https://lore.kernel.org/r/20220901130959.1285717-4-kan.liang@linux.intel.com

diff --git a/arch/powerpc/perf/core-book3s.c b/arch/powerpc/perf/core-book3s.c
index 13919eb..1ad1efd 100644 (file)
--- a/arch/powerpc/perf/core-book3s.c
+++ b/arch/powerpc/perf/core-book3s.c
@@ -2297,6 +2297,7 @@ static void record_and_restart(struct perf_event *event, unsigned long val,
                        cpuhw = this_cpu_ptr(&cpu_hw_events);
                        power_pmu_bhrb_read(event, cpuhw);
                        data.br_stack = &cpuhw->bhrb_stack;
+                       data.sample_flags |= PERF_SAMPLE_BRANCH_STACK;
                }
 
                if (event->attr.sample_type & PERF_SAMPLE_DATA_SRC &&

diff --git a/arch/x86/events/amd/core.c b/arch/x86/events/amd/core.c
index 36bede1..bd99d2a 100644 (file)
--- a/arch/x86/events/amd/core.c
+++ b/arch/x86/events/amd/core.c
@@ -929,8 +929,10 @@ static int amd_pmu_v2_handle_irq(struct pt_regs *regs)
                if (!x86_perf_event_set_period(event))
                        continue;
 
-               if (has_branch_stack(event))
+               if (has_branch_stack(event)) {
                        data.br_stack = &cpuc->lbr_stack;
+                       data.sample_flags |= PERF_SAMPLE_BRANCH_STACK;
+               }
 
                if (perf_event_overflow(event, &data, regs))
                        x86_pmu_stop(event, 0);

diff --git a/arch/x86/events/core.c b/arch/x86/events/core.c
index f969410..bb34a28 100644 (file)
--- a/arch/x86/events/core.c
+++ b/arch/x86/events/core.c
@@ -1714,8 +1714,10 @@ int x86_pmu_handle_irq(struct pt_regs *regs)
 
                perf_sample_data_init(&data, 0, event->hw.last_period);
 
-               if (has_branch_stack(event))
+               if (has_branch_stack(event)) {
                        data.br_stack = &cpuc->lbr_stack;
+                       data.sample_flags |= PERF_SAMPLE_BRANCH_STACK;
+               }
 
                if (perf_event_overflow(event, &data, regs))
                        x86_pmu_stop(event, 0);

diff --git a/arch/x86/events/intel/core.c b/arch/x86/events/intel/core.c
index 2db9349..ba101c2 100644 (file)
--- a/arch/x86/events/intel/core.c
+++ b/arch/x86/events/intel/core.c
@@ -2995,8 +2995,10 @@ static int handle_pmi_common(struct pt_regs *regs, u64 status)
 
                perf_sample_data_init(&data, 0, event->hw.last_period);
 
-               if (has_branch_stack(event))
+               if (has_branch_stack(event)) {
                        data.br_stack = &cpuc->lbr_stack;
+                       data.sample_flags |= PERF_SAMPLE_BRANCH_STACK;
+               }
 
                if (perf_event_overflow(event, &data, regs))
                        x86_pmu_stop(event, 0);

diff --git a/arch/x86/events/intel/ds.c b/arch/x86/events/intel/ds.c
index cdd857b..0489f75 100644 (file)
--- a/arch/x86/events/intel/ds.c
+++ b/arch/x86/events/intel/ds.c
@@ -1640,8 +1640,10 @@ static void setup_pebs_fixed_sample_data(struct perf_event *event,
                data->sample_flags |= PERF_SAMPLE_TIME;
        }
 
-       if (has_branch_stack(event))
+       if (has_branch_stack(event)) {
                data->br_stack = &cpuc->lbr_stack;
+               data->sample_flags |= PERF_SAMPLE_BRANCH_STACK;
+       }
 }
 
 static void adaptive_pebs_save_regs(struct pt_regs *regs,
@@ -1791,6 +1793,7 @@ static void setup_pebs_adaptive_sample_data(struct perf_event *event,
                if (has_branch_stack(event)) {
                        intel_pmu_store_pebs_lbrs(lbr);
                        data->br_stack = &cpuc->lbr_stack;
+                       data->sample_flags |= PERF_SAMPLE_BRANCH_STACK;
                }
        }
 

diff --git a/include/linux/perf_event.h b/include/linux/perf_event.h
index 0978165..1e12e79 100644 (file)
--- a/include/linux/perf_event.h
+++ b/include/linux/perf_event.h
@@ -1011,7 +1011,6 @@ struct perf_sample_data {
        u64                             sample_flags;
        u64                             addr;
        struct perf_raw_record          *raw;
-       struct perf_branch_stack        *br_stack;
        u64                             period;
        union perf_sample_weight        weight;
        u64                             txn;
@@ -1021,6 +1020,8 @@ struct perf_sample_data {
         * The other fields, optionally {set,used} by
         * perf_{prepare,output}_sample().
         */
+       struct perf_branch_stack        *br_stack;
+
        u64                             type;
        u64                             ip;
        struct {
@@ -1061,7 +1062,6 @@ static inline void perf_sample_data_init(struct perf_sample_data *data,
        data->sample_flags = 0;
        data->addr = addr;
        data->raw  = NULL;
-       data->br_stack = NULL;
        data->period = period;
        data->weight.full = 0;
        data->data_src.val = PERF_MEM_NA;

diff --git a/kernel/events/core.c b/kernel/events/core.c
index c9b9cb7..104c0c9 100644 (file)
--- a/kernel/events/core.c
+++ b/kernel/events/core.c
@@ -7052,7 +7052,7 @@ void perf_output_sample(struct perf_output_handle *handle,
        }
 
        if (sample_type & PERF_SAMPLE_BRANCH_STACK) {
-               if (data->br_stack) {
+               if (data->sample_flags & PERF_SAMPLE_BRANCH_STACK) {
                        size_t size;
 
                        size = data->br_stack->nr
@@ -7358,7 +7358,7 @@ void perf_prepare_sample(struct perf_event_header *header,
 
        if (sample_type & PERF_SAMPLE_BRANCH_STACK) {
                int size = sizeof(u64); /* nr */
-               if (data->br_stack) {
+               if (data->sample_flags & PERF_SAMPLE_BRANCH_STACK) {
                        if (perf_sample_save_hw_index(event))
                                size += sizeof(u64);