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perf: Supply task information to sched_task()
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To save/restore LBR call stack data in system-wide mode, the task_struct
information is required.

Extend the parameters of sched_task() to supply task_struct information.

When schedule in, the LBR call stack data for new task will be restored.
When schedule out, the LBR call stack data for old task will be saved.
Only need to pass the required task_struct information.

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/20250314172700.438923-4-kan.liang@linux.intel.com
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Kan Liang authored and Peter Zijlstra committed Mar 17, 2025
1 parent 506e64e commit d57e94f
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Showing 11 changed files with 42 additions and 26 deletions.
8 changes: 6 additions & 2 deletions arch/powerpc/perf/core-book3s.c
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Original file line number Diff line number Diff line change
Expand Up @@ -132,7 +132,10 @@ static unsigned long ebb_switch_in(bool ebb, struct cpu_hw_events *cpuhw)

static inline void power_pmu_bhrb_enable(struct perf_event *event) {}
static inline void power_pmu_bhrb_disable(struct perf_event *event) {}
static void power_pmu_sched_task(struct perf_event_pmu_context *pmu_ctx, bool sched_in) {}
static void power_pmu_sched_task(struct perf_event_pmu_context *pmu_ctx,
struct task_struct *task, bool sched_in)
{
}
static inline void power_pmu_bhrb_read(struct perf_event *event, struct cpu_hw_events *cpuhw) {}
static void pmao_restore_workaround(bool ebb) { }
#endif /* CONFIG_PPC32 */
Expand Down Expand Up @@ -444,7 +447,8 @@ static void power_pmu_bhrb_disable(struct perf_event *event)
/* Called from ctxsw to prevent one process's branch entries to
* mingle with the other process's entries during context switch.
*/
static void power_pmu_sched_task(struct perf_event_pmu_context *pmu_ctx, bool sched_in)
static void power_pmu_sched_task(struct perf_event_pmu_context *pmu_ctx,
struct task_struct *task, bool sched_in)
{
if (!ppmu->bhrb_nr)
return;
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3 changes: 2 additions & 1 deletion arch/s390/kernel/perf_pai_crypto.c
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Original file line number Diff line number Diff line change
Expand Up @@ -518,7 +518,8 @@ static void paicrypt_have_samples(void)
/* Called on schedule-in and schedule-out. No access to event structure,
* but for sampling only event CRYPTO_ALL is allowed.
*/
static void paicrypt_sched_task(struct perf_event_pmu_context *pmu_ctx, bool sched_in)
static void paicrypt_sched_task(struct perf_event_pmu_context *pmu_ctx,
struct task_struct *task, bool sched_in)
{
/* We started with a clean page on event installation. So read out
* results on schedule_out and if page was dirty, save old values.
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3 changes: 2 additions & 1 deletion arch/s390/kernel/perf_pai_ext.c
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Original file line number Diff line number Diff line change
Expand Up @@ -542,7 +542,8 @@ static void paiext_have_samples(void)
/* Called on schedule-in and schedule-out. No access to event structure,
* but for sampling only event NNPA_ALL is allowed.
*/
static void paiext_sched_task(struct perf_event_pmu_context *pmu_ctx, bool sched_in)
static void paiext_sched_task(struct perf_event_pmu_context *pmu_ctx,
struct task_struct *task, bool sched_in)
{
/* We started with a clean page on event installation. So read out
* results on schedule_out and if page was dirty, save old values.
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3 changes: 2 additions & 1 deletion arch/x86/events/amd/brs.c
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Original file line number Diff line number Diff line change
Expand Up @@ -381,7 +381,8 @@ static void amd_brs_poison_buffer(void)
* On ctxswin, sched_in = true, called after the PMU has started
* On ctxswout, sched_in = false, called before the PMU is stopped
*/
void amd_pmu_brs_sched_task(struct perf_event_pmu_context *pmu_ctx, bool sched_in)
void amd_pmu_brs_sched_task(struct perf_event_pmu_context *pmu_ctx,
struct task_struct *task, bool sched_in)
{
struct cpu_hw_events *cpuc = this_cpu_ptr(&cpu_hw_events);

Expand Down
3 changes: 2 additions & 1 deletion arch/x86/events/amd/lbr.c
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Original file line number Diff line number Diff line change
Expand Up @@ -371,7 +371,8 @@ void amd_pmu_lbr_del(struct perf_event *event)
perf_sched_cb_dec(event->pmu);
}

void amd_pmu_lbr_sched_task(struct perf_event_pmu_context *pmu_ctx, bool sched_in)
void amd_pmu_lbr_sched_task(struct perf_event_pmu_context *pmu_ctx,
struct task_struct *task, bool sched_in)
{
struct cpu_hw_events *cpuc = this_cpu_ptr(&cpu_hw_events);

Expand Down
5 changes: 3 additions & 2 deletions arch/x86/events/core.c
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Original file line number Diff line number Diff line change
Expand Up @@ -2638,9 +2638,10 @@ static const struct attribute_group *x86_pmu_attr_groups[] = {
NULL,
};

static void x86_pmu_sched_task(struct perf_event_pmu_context *pmu_ctx, bool sched_in)
static void x86_pmu_sched_task(struct perf_event_pmu_context *pmu_ctx,
struct task_struct *task, bool sched_in)
{
static_call_cond(x86_pmu_sched_task)(pmu_ctx, sched_in);
static_call_cond(x86_pmu_sched_task)(pmu_ctx, task, sched_in);
}

static void x86_pmu_swap_task_ctx(struct perf_event_pmu_context *prev_epc,
Expand Down
4 changes: 2 additions & 2 deletions arch/x86/events/intel/core.c
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Original file line number Diff line number Diff line change
Expand Up @@ -5294,10 +5294,10 @@ static void intel_pmu_cpu_dead(int cpu)
}

static void intel_pmu_sched_task(struct perf_event_pmu_context *pmu_ctx,
bool sched_in)
struct task_struct *task, bool sched_in)
{
intel_pmu_pebs_sched_task(pmu_ctx, sched_in);
intel_pmu_lbr_sched_task(pmu_ctx, sched_in);
intel_pmu_lbr_sched_task(pmu_ctx, task, sched_in);
}

static void intel_pmu_swap_task_ctx(struct perf_event_pmu_context *prev_epc,
Expand Down
3 changes: 2 additions & 1 deletion arch/x86/events/intel/lbr.c
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Original file line number Diff line number Diff line change
Expand Up @@ -539,7 +539,8 @@ void intel_pmu_lbr_swap_task_ctx(struct perf_event_pmu_context *prev_epc,
task_context_opt(next_ctx_data)->lbr_callstack_users);
}

void intel_pmu_lbr_sched_task(struct perf_event_pmu_context *pmu_ctx, bool sched_in)
void intel_pmu_lbr_sched_task(struct perf_event_pmu_context *pmu_ctx,
struct task_struct *task, bool sched_in)
{
struct cpu_hw_events *cpuc = this_cpu_ptr(&cpu_hw_events);
void *task_ctx;
Expand Down
14 changes: 9 additions & 5 deletions arch/x86/events/perf_event.h
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Original file line number Diff line number Diff line change
Expand Up @@ -875,7 +875,7 @@ struct x86_pmu {

void (*check_microcode)(void);
void (*sched_task)(struct perf_event_pmu_context *pmu_ctx,
bool sched_in);
struct task_struct *task, bool sched_in);

/*
* Intel Arch Perfmon v2+
Expand Down Expand Up @@ -1408,7 +1408,8 @@ void amd_pmu_lbr_reset(void);
void amd_pmu_lbr_read(void);
void amd_pmu_lbr_add(struct perf_event *event);
void amd_pmu_lbr_del(struct perf_event *event);
void amd_pmu_lbr_sched_task(struct perf_event_pmu_context *pmu_ctx, bool sched_in);
void amd_pmu_lbr_sched_task(struct perf_event_pmu_context *pmu_ctx,
struct task_struct *task, bool sched_in);
void amd_pmu_lbr_enable_all(void);
void amd_pmu_lbr_disable_all(void);
int amd_pmu_lbr_hw_config(struct perf_event *event);
Expand Down Expand Up @@ -1462,7 +1463,8 @@ static inline void amd_pmu_brs_del(struct perf_event *event)
perf_sched_cb_dec(event->pmu);
}

void amd_pmu_brs_sched_task(struct perf_event_pmu_context *pmu_ctx, bool sched_in);
void amd_pmu_brs_sched_task(struct perf_event_pmu_context *pmu_ctx,
struct task_struct *task, bool sched_in);
#else
static inline int amd_brs_init(void)
{
Expand All @@ -1487,7 +1489,8 @@ static inline void amd_pmu_brs_del(struct perf_event *event)
{
}

static inline void amd_pmu_brs_sched_task(struct perf_event_pmu_context *pmu_ctx, bool sched_in)
static inline void amd_pmu_brs_sched_task(struct perf_event_pmu_context *pmu_ctx,
struct task_struct *task, bool sched_in)
{
}

Expand Down Expand Up @@ -1670,7 +1673,8 @@ void intel_pmu_lbr_save_brstack(struct perf_sample_data *data,
void intel_pmu_lbr_swap_task_ctx(struct perf_event_pmu_context *prev_epc,
struct perf_event_pmu_context *next_epc);

void intel_pmu_lbr_sched_task(struct perf_event_pmu_context *pmu_ctx, bool sched_in);
void intel_pmu_lbr_sched_task(struct perf_event_pmu_context *pmu_ctx,
struct task_struct *task, bool sched_in);

u64 lbr_from_signext_quirk_wr(u64 val);

Expand Down
2 changes: 1 addition & 1 deletion include/linux/perf_event.h
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Original file line number Diff line number Diff line change
Expand Up @@ -494,7 +494,7 @@ struct pmu {
* context-switches callback
*/
void (*sched_task) (struct perf_event_pmu_context *pmu_ctx,
bool sched_in);
struct task_struct *task, bool sched_in);

/*
* Kmem cache of PMU specific data
Expand Down
20 changes: 11 additions & 9 deletions kernel/events/core.c
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Original file line number Diff line number Diff line change
Expand Up @@ -3613,7 +3613,8 @@ static void perf_event_swap_task_ctx_data(struct perf_event_context *prev_ctx,
}
}

static void perf_ctx_sched_task_cb(struct perf_event_context *ctx, bool sched_in)
static void perf_ctx_sched_task_cb(struct perf_event_context *ctx,
struct task_struct *task, bool sched_in)
{
struct perf_event_pmu_context *pmu_ctx;
struct perf_cpu_pmu_context *cpc;
Expand All @@ -3622,7 +3623,7 @@ static void perf_ctx_sched_task_cb(struct perf_event_context *ctx, bool sched_in
cpc = this_cpc(pmu_ctx->pmu);

if (cpc->sched_cb_usage && pmu_ctx->pmu->sched_task)
pmu_ctx->pmu->sched_task(pmu_ctx, sched_in);
pmu_ctx->pmu->sched_task(pmu_ctx, task, sched_in);
}
}

Expand Down Expand Up @@ -3685,7 +3686,7 @@ perf_event_context_sched_out(struct task_struct *task, struct task_struct *next)
WRITE_ONCE(ctx->task, next);
WRITE_ONCE(next_ctx->task, task);

perf_ctx_sched_task_cb(ctx, false);
perf_ctx_sched_task_cb(ctx, task, false);
perf_event_swap_task_ctx_data(ctx, next_ctx);

perf_ctx_enable(ctx, false);
Expand Down Expand Up @@ -3715,7 +3716,7 @@ perf_event_context_sched_out(struct task_struct *task, struct task_struct *next)
perf_ctx_disable(ctx, false);

inside_switch:
perf_ctx_sched_task_cb(ctx, false);
perf_ctx_sched_task_cb(ctx, task, false);
task_ctx_sched_out(ctx, NULL, EVENT_ALL);

perf_ctx_enable(ctx, false);
Expand Down Expand Up @@ -3757,7 +3758,8 @@ void perf_sched_cb_inc(struct pmu *pmu)
* PEBS requires this to provide PID/TID information. This requires we flush
* all queued PEBS records before we context switch to a new task.
*/
static void __perf_pmu_sched_task(struct perf_cpu_pmu_context *cpc, bool sched_in)
static void __perf_pmu_sched_task(struct perf_cpu_pmu_context *cpc,
struct task_struct *task, bool sched_in)
{
struct perf_cpu_context *cpuctx = this_cpu_ptr(&perf_cpu_context);
struct pmu *pmu;
Expand All @@ -3771,7 +3773,7 @@ static void __perf_pmu_sched_task(struct perf_cpu_pmu_context *cpc, bool sched_i
perf_ctx_lock(cpuctx, cpuctx->task_ctx);
perf_pmu_disable(pmu);

pmu->sched_task(cpc->task_epc, sched_in);
pmu->sched_task(cpc->task_epc, task, sched_in);

perf_pmu_enable(pmu);
perf_ctx_unlock(cpuctx, cpuctx->task_ctx);
Expand All @@ -3789,7 +3791,7 @@ static void perf_pmu_sched_task(struct task_struct *prev,
return;

list_for_each_entry(cpc, this_cpu_ptr(&sched_cb_list), sched_cb_entry)
__perf_pmu_sched_task(cpc, sched_in);
__perf_pmu_sched_task(cpc, sched_in ? next : prev, sched_in);
}

static void perf_event_switch(struct task_struct *task,
Expand Down Expand Up @@ -4088,7 +4090,7 @@ static void perf_event_context_sched_in(struct task_struct *task)
perf_ctx_lock(cpuctx, ctx);
perf_ctx_disable(ctx, false);

perf_ctx_sched_task_cb(ctx, true);
perf_ctx_sched_task_cb(ctx, task, true);

perf_ctx_enable(ctx, false);
perf_ctx_unlock(cpuctx, ctx);
Expand Down Expand Up @@ -4119,7 +4121,7 @@ static void perf_event_context_sched_in(struct task_struct *task)

perf_event_sched_in(cpuctx, ctx, NULL);

perf_ctx_sched_task_cb(cpuctx->task_ctx, true);
perf_ctx_sched_task_cb(cpuctx->task_ctx, task, true);

if (!RB_EMPTY_ROOT(&ctx->pinned_groups.tree))
perf_ctx_enable(&cpuctx->ctx, false);
Expand Down

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