Commit f42be865 authored by Kan Liang's avatar Kan Liang Committed by Peter Zijlstra
Browse files

perf/x86/intel/lbr: Use dynamic data structure for task_ctx 



The type of task_ctx is hardcoded as struct x86_perf_task_context,
which doesn't apply for Architecture LBR. For example, Architecture LBR
doesn't have the TOS MSR. The number of LBR entries is variable. A new
struct will be introduced for Architecture LBR. Perf has to determine
the type of task_ctx at run time.

The type of task_ctx pointer is changed to 'void *', which will be
determined at run time.

The generic LBR optimization can be shared between Architecture LBR and
model-specific LBR. Both need to access the structure for the generic
LBR optimization. A helper task_context_opt() is introduced to retrieve
the pointer of the structure at run time.

Signed-off-by: default avatarKan Liang <kan.liang@linux.intel.com>
Signed-off-by: default avatarPeter Zijlstra (Intel) <peterz@infradead.org>
Link: https://lkml.kernel.org/r/1593780569-62993-7-git-send-email-kan.liang@linux.intel.com
parent 530bfff6

arch/x86/events/intel/lbr.c

+26 −33
Original line number Diff line number Diff line
@@ -355,18 +355,17 @@ void intel_pmu_lbr_restore(void *ctx) 
		wrmsrl(MSR_LBR_SELECT, task_ctx->lbr_sel);

}



static __always_inline bool

lbr_is_reset_in_cstate(struct x86_perf_task_context *task_ctx)

static __always_inline bool lbr_is_reset_in_cstate(void *ctx)

{

	return !rdlbr_from(task_ctx->tos);

	return !rdlbr_from(((struct x86_perf_task_context *)ctx)->tos);

}



static void __intel_pmu_lbr_restore(struct x86_perf_task_context *task_ctx)

static void __intel_pmu_lbr_restore(void *ctx)

{

	struct cpu_hw_events *cpuc = this_cpu_ptr(&cpu_hw_events);



	if (task_ctx->opt.lbr_callstack_users == 0 ||

	    task_ctx->opt.lbr_stack_state == LBR_NONE) {

	if (task_context_opt(ctx)->lbr_callstack_users == 0 ||

	    task_context_opt(ctx)->lbr_stack_state == LBR_NONE) {

		intel_pmu_lbr_reset();

		return;

	}
@@ -376,16 +375,16 @@ static void __intel_pmu_lbr_restore(struct x86_perf_task_context *task_ctx) 
	 * - No one else touched them, and

	 * - Was not cleared in Cstate

	 */

	if ((task_ctx == cpuc->last_task_ctx) &&

	    (task_ctx->opt.log_id == cpuc->last_log_id) &&

	    !lbr_is_reset_in_cstate(task_ctx)) {

		task_ctx->opt.lbr_stack_state = LBR_NONE;

	if ((ctx == cpuc->last_task_ctx) &&

	    (task_context_opt(ctx)->log_id == cpuc->last_log_id) &&

	    !lbr_is_reset_in_cstate(ctx)) {

		task_context_opt(ctx)->lbr_stack_state = LBR_NONE;

		return;

	}



	x86_pmu.lbr_restore(task_ctx);

	x86_pmu.lbr_restore(ctx);



	task_ctx->opt.lbr_stack_state = LBR_NONE;

	task_context_opt(ctx)->lbr_stack_state = LBR_NONE;

}



void intel_pmu_lbr_save(void *ctx)
@@ -415,27 +414,27 @@ void intel_pmu_lbr_save(void *ctx) 
		rdmsrl(MSR_LBR_SELECT, task_ctx->lbr_sel);

}



static void __intel_pmu_lbr_save(struct x86_perf_task_context *task_ctx)

static void __intel_pmu_lbr_save(void *ctx)

{

	struct cpu_hw_events *cpuc = this_cpu_ptr(&cpu_hw_events);



	if (task_ctx->opt.lbr_callstack_users == 0) {

		task_ctx->opt.lbr_stack_state = LBR_NONE;

	if (task_context_opt(ctx)->lbr_callstack_users == 0) {

		task_context_opt(ctx)->lbr_stack_state = LBR_NONE;

		return;

	}



	x86_pmu.lbr_save(task_ctx);

	x86_pmu.lbr_save(ctx);



	task_ctx->opt.lbr_stack_state = LBR_VALID;

	task_context_opt(ctx)->lbr_stack_state = LBR_VALID;



	cpuc->last_task_ctx = task_ctx;

	cpuc->last_log_id = ++task_ctx->opt.log_id;

	cpuc->last_task_ctx = ctx;

	cpuc->last_log_id = ++task_context_opt(ctx)->log_id;

}



void intel_pmu_lbr_swap_task_ctx(struct perf_event_context *prev,

				 struct perf_event_context *next)

{

	struct x86_perf_task_context *prev_ctx_data, *next_ctx_data;

	void *prev_ctx_data, *next_ctx_data;



	swap(prev->task_ctx_data, next->task_ctx_data);
@@ -451,14 +450,14 @@ void intel_pmu_lbr_swap_task_ctx(struct perf_event_context *prev, 
	if (!prev_ctx_data || !next_ctx_data)

		return;



	swap(prev_ctx_data->opt.lbr_callstack_users,

	     next_ctx_data->opt.lbr_callstack_users);

	swap(task_context_opt(prev_ctx_data)->lbr_callstack_users,

	     task_context_opt(next_ctx_data)->lbr_callstack_users);

}



void intel_pmu_lbr_sched_task(struct perf_event_context *ctx, bool sched_in)

{

	struct cpu_hw_events *cpuc = this_cpu_ptr(&cpu_hw_events);

	struct x86_perf_task_context *task_ctx;

	void *task_ctx;



	if (!cpuc->lbr_users)

		return;
@@ -495,7 +494,6 @@ static inline bool branch_user_callstack(unsigned br_sel) 
void intel_pmu_lbr_add(struct perf_event *event)

{

	struct cpu_hw_events *cpuc = this_cpu_ptr(&cpu_hw_events);

	struct x86_perf_task_context *task_ctx;



	if (!x86_pmu.lbr_nr)

		return;
@@ -505,10 +503,8 @@ void intel_pmu_lbr_add(struct perf_event *event) 


	cpuc->br_sel = event->hw.branch_reg.reg;



	if (branch_user_callstack(cpuc->br_sel) && event->ctx->task_ctx_data) {

		task_ctx = event->ctx->task_ctx_data;

		task_ctx->opt.lbr_callstack_users++;

	}

	if (branch_user_callstack(cpuc->br_sel) && event->ctx->task_ctx_data)

		task_context_opt(event->ctx->task_ctx_data)->lbr_callstack_users++;



	/*

	 * Request pmu::sched_task() callback, which will fire inside the
@@ -539,16 +535,13 @@ void intel_pmu_lbr_add(struct perf_event *event) 
void intel_pmu_lbr_del(struct perf_event *event)

{

	struct cpu_hw_events *cpuc = this_cpu_ptr(&cpu_hw_events);

	struct x86_perf_task_context *task_ctx;



	if (!x86_pmu.lbr_nr)

		return;



	if (branch_user_callstack(cpuc->br_sel) &&

	    event->ctx->task_ctx_data) {

		task_ctx = event->ctx->task_ctx_data;

		task_ctx->opt.lbr_callstack_users--;

	}

	    event->ctx->task_ctx_data)

		task_context_opt(event->ctx->task_ctx_data)->lbr_callstack_users--;



	if (event->hw.flags & PERF_X86_EVENT_LBR_SELECT)

		cpuc->lbr_select = 0;

arch/x86/events/perf_event.h

+6 −1
Original line number Diff line number Diff line
@@ -247,7 +247,7 @@ struct cpu_hw_events { 
	struct perf_branch_entry	lbr_entries[MAX_LBR_ENTRIES];

	struct er_account		*lbr_sel;

	u64				br_sel;

	struct x86_perf_task_context	*last_task_ctx;

	void				*last_task_ctx;

	int				last_log_id;

	int				lbr_select;
@@ -800,6 +800,11 @@ static struct perf_pmu_events_ht_attr event_attr_##v = { \ 
struct pmu *x86_get_pmu(void);

extern struct x86_pmu x86_pmu __read_mostly;



static __always_inline struct x86_perf_task_context_opt *task_context_opt(void *ctx)

{

	return &((struct x86_perf_task_context *)ctx)->opt;

}



static inline bool x86_pmu_has_lbr_callstack(void)

{

	return  x86_pmu.lbr_sel_map &&

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