perf tools: Allow synthesizing the build id for kernel/modules/tasks in PERF_RECORD_MMAP2

Adding build id to synthesized mmap2 events for everything -
kernel/modules/tasks, when symbol_conf.buildid_mmap2 is true.

Signed-off-by: Jiri Olsa <jolsa@kernel.org>
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: Ian Rogers <irogers@google.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/20201214105457.543111-11-jolsa@kernel.org
Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>

tools/perf/util/synthetic-events.c

@@ -347,6 +347,31 @@ static bool read_proc_maps_line(struct io *io, __u64 *start, __u64 *end,
 	}
 }
 
+static void perf_record_mmap2__read_build_id(struct perf_record_mmap2 *event,
+					     bool is_kernel)
+{
+	struct build_id bid;
+	int rc;
+
+	if (is_kernel)
+		rc = sysfs__read_build_id("/sys/kernel/notes", &bid);
+	else
+		rc = filename__read_build_id(event->filename, &bid) > 0 ? 0 : -1;
+
+	if (rc == 0) {
+		memcpy(event->build_id, bid.data, sizeof(bid.data));
+		event->build_id_size = (u8) bid.size;
+		event->header.misc |= PERF_RECORD_MISC_MMAP_BUILD_ID;
+		event->__reserved_1 = 0;
+		event->__reserved_2 = 0;
+	} else {
+		if (event->filename[0] == '/') {
+			pr_debug2("Failed to read build ID for %s\n",
+				  event->filename);
+		}
+	}
+}
+
 int perf_event__synthesize_mmap_events(struct perf_tool *tool,
 				       union perf_event *event,
 				       pid_t pid, pid_t tgid,
@@ -453,6 +478,9 @@ out:
 		event->mmap2.pid = tgid;
 		event->mmap2.tid = pid;
 
+		if (symbol_conf.buildid_mmap2)
+			perf_record_mmap2__read_build_id(&event->mmap2, false);
+
 		if (perf_tool__process_synth_event(tool, event, machine, process) != 0) {
 			rc = -1;
 			break;
@@ -633,6 +661,8 @@ int perf_event__synthesize_modules(struct perf_tool *tool, perf_event__handler_t
 
 			memcpy(event->mmap2.filename, pos->dso->long_name,
 			       pos->dso->long_name_len + 1);
+
+			perf_record_mmap2__read_build_id(&event->mmap2, false);
 		} else {
 			size = PERF_ALIGN(pos->dso->long_name_len + 1, sizeof(u64));
 			event->mmap.header.type = PERF_RECORD_MMAP;
@@ -1053,6 +1083,8 @@ static int __perf_event__synthesize_kernel_mmap(struct perf_tool *tool,
 		event->mmap2.start = map->start;
 		event->mmap2.len   = map->end - event->mmap.start;
 		event->mmap2.pid   = machine->pid;
+
+		perf_record_mmap2__read_build_id(&event->mmap2, true);
 	} else {
 		size = snprintf(event->mmap.filename, sizeof(event->mmap.filename),
 				"%s%s", machine->mmap_name, kmap->ref_reloc_sym->name) + 1;