perf tools: Allow using PERF_RECORD_MMAP2 to synthesize the kernel modules maps

Allow using PERF_RECORD_MMAP2 to synthesize the kernel modules maps so
that we can use PERF_RECORD_MMAP2 to encode the kernel modules build ids
in the following csets.

It's enabled by a new symbol_conf.buildid_mmap2 bool field, which will
be switchable in following changes.
Signed-off-by: Jiri Olsa <jolsa@kernel.org>
Acked-by: Ian Rogers <irogers@google.com>
Acked-by: Namhyung Kim <namhyung@kernel.org>
Cc: Adrian Hunter <adrian.hunter@intel.com>
Cc: Alexander Shishkin <alexander.shishkin@linux.intel.com>
Cc: Alexei Budankov <abudankov@huawei.com>
Cc: Andi Kleen <ak@linux.intel.com>
Cc: Mark Rutland <mark.rutland@arm.com>
Cc: Michael Petlan <mpetlan@redhat.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Song Liu <songliubraving@fb.com>
Cc: Stephane Eranian <eranian@google.com>
Link: http://lore.kernel.org/lkml/20201214105457.543111-10-jolsa@kernel.orgSigned-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>

tools/perf/util/synthetic-events.c

@@ -596,16 +596,17 @@ int perf_event__synthesize_modules(struct perf_tool *tool, perf_event__handler_t
 	int rc = 0;
 	struct map *pos;
 	struct maps *maps = machine__kernel_maps(machine);
-	union perf_event *event = zalloc((sizeof(event->mmap) +
-					  machine->id_hdr_size));
+	union perf_event *event;
+	size_t size = symbol_conf.buildid_mmap2 ?
+			sizeof(event->mmap2) : sizeof(event->mmap);
+
+	event = zalloc(size + machine->id_hdr_size);
 	if (event == NULL) {
 		pr_debug("Not enough memory synthesizing mmap event "
 			 "for kernel modules\n");
 		return -1;
 	}
 
-	event->header.type = PERF_RECORD_MMAP;
-
 	/*
 	 * kernel uses 0 for user space maps, see kernel/perf_event.c
 	 * __perf_event_mmap
@@ -616,23 +617,37 @@ int perf_event__synthesize_modules(struct perf_tool *tool, perf_event__handler_t
 		event->header.misc = PERF_RECORD_MISC_GUEST_KERNEL;
 
 	maps__for_each_entry(maps, pos) {
-		size_t size;
-
 		if (!__map__is_kmodule(pos))
 			continue;
 
-		size = PERF_ALIGN(pos->dso->long_name_len + 1, sizeof(u64));
-		event->mmap.header.type = PERF_RECORD_MMAP;
-		event->mmap.header.size = (sizeof(event->mmap) -
-				        (sizeof(event->mmap.filename) - size));
-		memset(event->mmap.filename + size, 0, machine->id_hdr_size);
-		event->mmap.header.size += machine->id_hdr_size;
-		event->mmap.start = pos->start;
-		event->mmap.len   = pos->end - pos->start;
-		event->mmap.pid   = machine->pid;
+		if (symbol_conf.buildid_mmap2) {
+			size = PERF_ALIGN(pos->dso->long_name_len + 1, sizeof(u64));
+			event->mmap2.header.type = PERF_RECORD_MMAP2;
+			event->mmap2.header.size = (sizeof(event->mmap2) -
+						(sizeof(event->mmap2.filename) - size));
+			memset(event->mmap2.filename + size, 0, machine->id_hdr_size);
+			event->mmap2.header.size += machine->id_hdr_size;
+			event->mmap2.start = pos->start;
+			event->mmap2.len   = pos->end - pos->start;
+			event->mmap2.pid   = machine->pid;
+
+			memcpy(event->mmap2.filename, pos->dso->long_name,
+			       pos->dso->long_name_len + 1);
+		} else {
+			size = PERF_ALIGN(pos->dso->long_name_len + 1, sizeof(u64));
+			event->mmap.header.type = PERF_RECORD_MMAP;
+			event->mmap.header.size = (sizeof(event->mmap) -
+						(sizeof(event->mmap.filename) - size));
+			memset(event->mmap.filename + size, 0, machine->id_hdr_size);
+			event->mmap.header.size += machine->id_hdr_size;
+			event->mmap.start = pos->start;
+			event->mmap.len   = pos->end - pos->start;
+			event->mmap.pid   = machine->pid;
+
+			memcpy(event->mmap.filename, pos->dso->long_name,
+			       pos->dso->long_name_len + 1);
+		}
 
-		memcpy(event->mmap.filename, pos->dso->long_name,
-		       pos->dso->long_name_len + 1);
 		if (perf_tool__process_synth_event(tool, event, machine, process) != 0) {
 			rc = -1;
 			break;