perf mem: Introduce weak function perf_mem_events__ptr()

Different architectures might use different event or different event
parameters for memory profiling, this patch introduces a weak
perf_mem_events__ptr() function which allows to return back a
architecture specific memory event.

Since the variable 'perf_mem_events' can be only accessed by the
perf_mem_events__ptr() function, mark the variable as 'static', this
allows the architectures to define its own memory event array.
Signed-off-by: Leo Yan <leo.yan@linaro.org>
Acked-by: Jiri Olsa <jolsa@redhat.com>
Link: https://lore.kernel.org/r/20201106094853.21082-3-leo.yan@linaro.orgSigned-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>

tools/perf/builtin-c2c.c

@@ -2867,6 +2867,7 @@ static int perf_c2c__record(int argc, const char **argv)
 	int ret;
 	bool all_user = false, all_kernel = false;
 	bool event_set = false;
+	struct perf_mem_event *e;
 	struct option options[] = {
 	OPT_CALLBACK('e', "event", &event_set, "event",
 		     "event selector. Use 'perf c2c record -e list' to list available events",
@@ -2894,11 +2895,15 @@ static int perf_c2c__record(int argc, const char **argv)
 	rec_argv[i++] = "record";
 
 	if (!event_set) {
-		perf_mem_events[PERF_MEM_EVENTS__LOAD].record  = true;
-		perf_mem_events[PERF_MEM_EVENTS__STORE].record = true;
+		e = perf_mem_events__ptr(PERF_MEM_EVENTS__LOAD);
+		e->record = true;
+
+		e = perf_mem_events__ptr(PERF_MEM_EVENTS__STORE);
+		e->record = true;
 	}
 
-	if (perf_mem_events[PERF_MEM_EVENTS__LOAD].record)
+	e = perf_mem_events__ptr(PERF_MEM_EVENTS__LOAD);
+	if (e->record)
 		rec_argv[i++] = "-W";
 
 	rec_argv[i++] = "-d";
@@ -2906,12 +2911,13 @@ static int perf_c2c__record(int argc, const char **argv)
 	rec_argv[i++] = "--sample-cpu";
 
 	for (j = 0; j < PERF_MEM_EVENTS__MAX; j++) {
-		if (!perf_mem_events[j].record)
+		e = perf_mem_events__ptr(j);
+		if (!e->record)
 			continue;
 
-		if (!perf_mem_events[j].supported) {
+		if (!e->supported) {
 			pr_err("failed: event '%s' not supported\n",
-			       perf_mem_events[j].name);
+			       perf_mem_events__name(j));
 			free(rec_argv);
 			return -1;
 		}

tools/perf/builtin-mem.c

@@ -64,6 +64,7 @@ static int __cmd_record(int argc, const char **argv, struct perf_mem *mem)
 	const char **rec_argv;
 	int ret;
 	bool all_user = false, all_kernel = false;
+	struct perf_mem_event *e;
 	struct option options[] = {
 	OPT_CALLBACK('e', "event", &mem, "event",
 		     "event selector. use 'perf mem record -e list' to list available events",
@@ -86,13 +87,18 @@ static int __cmd_record(int argc, const char **argv, struct perf_mem *mem)
 
 	rec_argv[i++] = "record";
 
-	if (mem->operation & MEM_OPERATION_LOAD)
-		perf_mem_events[PERF_MEM_EVENTS__LOAD].record = true;
+	if (mem->operation & MEM_OPERATION_LOAD) {
+		e = perf_mem_events__ptr(PERF_MEM_EVENTS__LOAD);
+		e->record = true;
+	}
 
-	if (mem->operation & MEM_OPERATION_STORE)
-		perf_mem_events[PERF_MEM_EVENTS__STORE].record = true;
+	if (mem->operation & MEM_OPERATION_STORE) {
+		e = perf_mem_events__ptr(PERF_MEM_EVENTS__STORE);
+		e->record = true;
+	}
 
-	if (perf_mem_events[PERF_MEM_EVENTS__LOAD].record)
+	e = perf_mem_events__ptr(PERF_MEM_EVENTS__LOAD);
+	if (e->record)
 		rec_argv[i++] = "-W";
 
 	rec_argv[i++] = "-d";
@@ -101,10 +107,11 @@ static int __cmd_record(int argc, const char **argv, struct perf_mem *mem)
 		rec_argv[i++] = "--phys-data";
 
 	for (j = 0; j < PERF_MEM_EVENTS__MAX; j++) {
-		if (!perf_mem_events[j].record)
+		e = perf_mem_events__ptr(j);
+		if (!e->record)
 			continue;
 
-		if (!perf_mem_events[j].supported) {
+		if (!e->supported) {
 			pr_err("failed: event '%s' not supported\n",
 			       perf_mem_events__name(j));
 			free(rec_argv);

tools/perf/util/mem-events.c

@@ -17,7 +17,7 @@ unsigned int perf_mem_events__loads_ldlat = 30;
 
 #define E(t, n, s) { .tag = t, .name = n, .sysfs_name = s }
 
-struct perf_mem_event perf_mem_events[PERF_MEM_EVENTS__MAX] = {
+static struct perf_mem_event perf_mem_events[PERF_MEM_EVENTS__MAX] = {
 	E("ldlat-loads",	"cpu/mem-loads,ldlat=%u/P",	"cpu/events/mem-loads"),
 	E("ldlat-stores",	"cpu/mem-stores/P",		"cpu/events/mem-stores"),
 };
@@ -28,19 +28,31 @@ struct perf_mem_event perf_mem_events[PERF_MEM_EVENTS__MAX] = {
 static char mem_loads_name[100];
 static bool mem_loads_name__init;
 
+struct perf_mem_event * __weak perf_mem_events__ptr(int i)
+{
+	if (i >= PERF_MEM_EVENTS__MAX)
+		return NULL;
+
+	return &perf_mem_events[i];
+}
+
 char * __weak perf_mem_events__name(int i)
 {
+	struct perf_mem_event *e = perf_mem_events__ptr(i);
+
+	if (!e)
+		return NULL;
+
 	if (i == PERF_MEM_EVENTS__LOAD) {
 		if (!mem_loads_name__init) {
 			mem_loads_name__init = true;
 			scnprintf(mem_loads_name, sizeof(mem_loads_name),
-				  perf_mem_events[i].name,
-				  perf_mem_events__loads_ldlat);
+				  e->name, perf_mem_events__loads_ldlat);
 		}
 		return mem_loads_name;
 	}
 
-	return (char *)perf_mem_events[i].name;
+	return (char *)e->name;
 }
 
 int perf_mem_events__parse(const char *str)
@@ -61,7 +73,7 @@ int perf_mem_events__parse(const char *str)
 
 	while (tok) {
 		for (j = 0; j < PERF_MEM_EVENTS__MAX; j++) {
-			struct perf_mem_event *e = &perf_mem_events[j];
+			struct perf_mem_event *e = perf_mem_events__ptr(j);
 
 			if (strstr(e->tag, tok))
 				e->record = found = true;
@@ -90,7 +102,7 @@ int perf_mem_events__init(void)
 
 	for (j = 0; j < PERF_MEM_EVENTS__MAX; j++) {
 		char path[PATH_MAX];
-		struct perf_mem_event *e = &perf_mem_events[j];
+		struct perf_mem_event *e = perf_mem_events__ptr(j);
 		struct stat st;
 
 		scnprintf(path, PATH_MAX, "%s/devices/%s",
@@ -108,7 +120,7 @@ void perf_mem_events__list(void)
 	int j;
 
 	for (j = 0; j < PERF_MEM_EVENTS__MAX; j++) {
-		struct perf_mem_event *e = &perf_mem_events[j];
+		struct perf_mem_event *e = perf_mem_events__ptr(j);
 
 		fprintf(stderr, "%-13s%-*s%s\n",
 			e->tag,

tools/perf/util/mem-events.h

@@ -31,13 +31,13 @@ enum {
 	PERF_MEM_EVENTS__MAX,
 };
 
-extern struct perf_mem_event perf_mem_events[PERF_MEM_EVENTS__MAX];
 extern unsigned int perf_mem_events__loads_ldlat;
 
 int perf_mem_events__parse(const char *str);
 int perf_mem_events__init(void);
 
 char *perf_mem_events__name(int i);
+struct perf_mem_event *perf_mem_events__ptr(int i);
 
 void perf_mem_events__list(void);