perf/x86/amd/core: Add generic branch record interfaces

AMD processors that are capable of recording branches support either Branch
Sampling (BRS) or Last Branch Record (LBR). In preparation for adding Last
Branch Record Extension Version 2 (LbrExtV2) support, introduce new static
calls which act as gateways to call into the feature-dependent functions
based on what is available on the processor.
Signed-off-by: Sandipan Das <sandipan.das@amd.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Link: https://lore.kernel.org/r/b75dbc32663cb395f0d701167e952c6a6b0445a3.1660211399.git.sandipan.das@amd.com

arch/x86/events/amd/core.c

@@ -330,6 +330,8 @@ static inline bool amd_is_pair_event_code(struct hw_perf_event *hwc)
 	}
 }
 
+DEFINE_STATIC_CALL_RET0(amd_pmu_branch_hw_config, *x86_pmu.hw_config);
+
 static int amd_core_hw_config(struct perf_event *event)
 {
 	if (event->attr.exclude_host && event->attr.exclude_guest)
@@ -349,7 +351,7 @@ static int amd_core_hw_config(struct perf_event *event)
 		event->hw.flags |= PERF_X86_EVENT_PAIR;
 
 	if (has_branch_stack(event))
-		return amd_brs_hw_config(event);
+		return static_call(amd_pmu_branch_hw_config)(event);
 
 	return 0;
 }
@@ -518,8 +520,14 @@ static struct amd_nb *amd_alloc_nb(int cpu)
 	return nb;
 }
 
+typedef void (amd_pmu_branch_reset_t)(void);
+DEFINE_STATIC_CALL_NULL(amd_pmu_branch_reset, amd_pmu_branch_reset_t);
+
 static void amd_pmu_cpu_reset(int cpu)
 {
+	if (x86_pmu.lbr_nr)
+		static_call(amd_pmu_branch_reset)();
+
 	if (x86_pmu.version < 2)
 		return;
 
@@ -576,7 +584,6 @@ static void amd_pmu_cpu_starting(int cpu)
 	cpuc->amd_nb->nb_id = nb_id;
 	cpuc->amd_nb->refcnt++;
 
-	amd_brs_reset();
 	amd_pmu_cpu_reset(cpu);
 }
 
@@ -771,16 +778,20 @@ static void amd_pmu_v2_disable_all(void)
 	amd_pmu_check_overflow();
 }
 
+DEFINE_STATIC_CALL_NULL(amd_pmu_branch_add, *x86_pmu.add);
+
 static void amd_pmu_add_event(struct perf_event *event)
 {
 	if (needs_branch_stack(event))
-		amd_pmu_brs_add(event);
+		static_call(amd_pmu_branch_add)(event);
 }
 
+DEFINE_STATIC_CALL_NULL(amd_pmu_branch_del, *x86_pmu.del);
+
 static void amd_pmu_del_event(struct perf_event *event)
 {
 	if (needs_branch_stack(event))
-		amd_pmu_brs_del(event);
+		static_call(amd_pmu_branch_del)(event);
 }
 
 /*
@@ -1184,13 +1195,6 @@ static ssize_t amd_event_sysfs_show(char *page, u64 config)
 	return x86_event_sysfs_show(page, config, event);
 }
 
-static void amd_pmu_sched_task(struct perf_event_context *ctx,
-				 bool sched_in)
-{
-	if (sched_in && x86_pmu.lbr_nr)
-		amd_pmu_brs_sched_task(ctx, sched_in);
-}
-
 static u64 amd_pmu_limit_period(struct perf_event *event, u64 left)
 {
 	/*
@@ -1375,8 +1379,14 @@ static int __init amd_core_pmu_init(void)
 	 */
 	if (boot_cpu_data.x86 >= 0x19 && !amd_brs_init()) {
 		x86_pmu.get_event_constraints = amd_get_event_constraints_f19h;
-		x86_pmu.sched_task = amd_pmu_sched_task;
+		x86_pmu.sched_task = amd_pmu_brs_sched_task;
 		x86_pmu.limit_period = amd_pmu_limit_period;
+
+		static_call_update(amd_pmu_branch_hw_config, amd_brs_hw_config);
+		static_call_update(amd_pmu_branch_reset, amd_brs_reset);
+		static_call_update(amd_pmu_branch_add, amd_pmu_brs_add);
+		static_call_update(amd_pmu_branch_del, amd_pmu_brs_del);
+
 		/*
 		 * put_event_constraints callback same as Fam17h, set above
 		 */