perf/x86: Remove swap_task_ctx()

The pmu specific data is saved in task_struct now. It doesn't need to
swap between context.

Remove swap_task_ctx() support.

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/20250314172700.438923-6-kan.liang@linux.intel.com

Author: Kan Liang

arch/x86/events/core.c

@@ -87,7 +87,6 @@ DEFINE_STATIC_CALL_NULL(x86_pmu_commit_scheduling, *x86_pmu.commit_scheduling);
 DEFINE_STATIC_CALL_NULL(x86_pmu_stop_scheduling,   *x86_pmu.stop_scheduling);
 
 DEFINE_STATIC_CALL_NULL(x86_pmu_sched_task,    *x86_pmu.sched_task);
-DEFINE_STATIC_CALL_NULL(x86_pmu_swap_task_ctx, *x86_pmu.swap_task_ctx);
 
 DEFINE_STATIC_CALL_NULL(x86_pmu_drain_pebs,   *x86_pmu.drain_pebs);
 DEFINE_STATIC_CALL_NULL(x86_pmu_pebs_aliases, *x86_pmu.pebs_aliases);
@@ -2039,7 +2038,6 @@ static void x86_pmu_static_call_update(void)
 	static_call_update(x86_pmu_stop_scheduling, x86_pmu.stop_scheduling);
 
 	static_call_update(x86_pmu_sched_task, x86_pmu.sched_task);
-	static_call_update(x86_pmu_swap_task_ctx, x86_pmu.swap_task_ctx);
 
 	static_call_update(x86_pmu_drain_pebs, x86_pmu.drain_pebs);
 	static_call_update(x86_pmu_pebs_aliases, x86_pmu.pebs_aliases);
@@ -2644,12 +2642,6 @@ static void x86_pmu_sched_task(struct perf_event_pmu_context *pmu_ctx,
 	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,
-				  struct perf_event_pmu_context *next_epc)
-{
-	static_call_cond(x86_pmu_swap_task_ctx)(prev_epc, next_epc);
-}
-
 void perf_check_microcode(void)
 {
 	if (x86_pmu.check_microcode)
@@ -2714,7 +2706,6 @@ static struct pmu pmu = {
 
 	.event_idx		= x86_pmu_event_idx,
 	.sched_task		= x86_pmu_sched_task,
-	.swap_task_ctx		= x86_pmu_swap_task_ctx,
 	.check_period		= x86_pmu_check_period,
 
 	.aux_output_match	= x86_pmu_aux_output_match,

arch/x86/events/intel/core.c

@@ -5300,12 +5300,6 @@ static void intel_pmu_sched_task(struct perf_event_pmu_context *pmu_ctx,
 	intel_pmu_lbr_sched_task(pmu_ctx, task, sched_in);
 }
 
-static void intel_pmu_swap_task_ctx(struct perf_event_pmu_context *prev_epc,
-				    struct perf_event_pmu_context *next_epc)
-{
-	intel_pmu_lbr_swap_task_ctx(prev_epc, next_epc);
-}
-
 static int intel_pmu_check_period(struct perf_event *event, u64 value)
 {
 	return intel_pmu_has_bts_period(event, value) ? -EINVAL : 0;
@@ -5474,7 +5468,6 @@ static __initconst const struct x86_pmu intel_pmu = {
 
 	.guest_get_msrs		= intel_guest_get_msrs,
 	.sched_task		= intel_pmu_sched_task,
-	.swap_task_ctx		= intel_pmu_swap_task_ctx,
 
 	.check_period		= intel_pmu_check_period,
 

arch/x86/events/intel/lbr.c

@@ -522,29 +522,6 @@ static void __intel_pmu_lbr_save(void *ctx)
 	cpuc->last_log_id = ++task_context_opt(ctx)->log_id;
 }
 
-void intel_pmu_lbr_swap_task_ctx(struct perf_event_pmu_context *prev_epc,
-				 struct perf_event_pmu_context *next_epc)
-{
-	void *prev_ctx_data, *next_ctx_data;
-
-	swap(prev_epc->task_ctx_data, next_epc->task_ctx_data);
-
-	/*
-	 * Architecture specific synchronization makes sense in case
-	 * both prev_epc->task_ctx_data and next_epc->task_ctx_data
-	 * pointers are allocated.
-	 */
-
-	prev_ctx_data = next_epc->task_ctx_data;
-	next_ctx_data = prev_epc->task_ctx_data;
-
-	if (!prev_ctx_data || !next_ctx_data)
-		return;
-
-	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_pmu_context *pmu_ctx,
 			      struct task_struct *task, bool sched_in)
 {

arch/x86/events/perf_event.h

@@ -958,14 +958,6 @@ struct x86_pmu {
 	 */
 	int		num_topdown_events;
 
-	/*
-	 * perf task context (i.e. struct perf_event_pmu_context::task_ctx_data)
-	 * switch helper to bridge calls from perf/core to perf/x86.
-	 * See struct pmu::swap_task_ctx() usage for examples;
-	 */
-	void		(*swap_task_ctx)(struct perf_event_pmu_context *prev_epc,
-					 struct perf_event_pmu_context *next_epc);
-
 	/*
 	 * AMD bits
 	 */
@@ -1671,9 +1663,6 @@ void intel_pmu_lbr_save_brstack(struct perf_sample_data *data,
 				struct cpu_hw_events *cpuc,
 				struct perf_event *event);
 
-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,
 			      struct task_struct *task, bool sched_in);