perf dso: Move build_id to dso_id

The dso_id previously contained the major, minor, inode and inode
generation information from a mmap2 event - the inode generation would
be zero when reading from /proc/pid/maps. The build_id was in the
dso. With build ID mmap2 events these fields wouldn't be initialized
which would largely mean the special empty case where any dso would
match for equality. This isn't desirable as if a dso is replaced we
want the comparison to yield a difference.

To support detecting the difference between DSOs based on build_id,
move the build_id out of the DSO and into the dso_id. The dso_id is
also stored in the DSO so nothing is lost. Capture in the dso_id what
parts have been initialized and rename dso_id__inject to
dso_id__improve_id so that it is clear the dso_id is being improved
upon with additional information. With the build_id in the dso_id, use
memcmp to compare for equality.

Signed-off-by: Ian Rogers <[e-mail]>
Link: https://lore.kernel.org/r/[e-mail]
Signed-off-by: Namhyung Kim <[e-mail]>

tools/perf/builtin-buildid-list.c

···
 
 	memset(bid_buf, 0, sizeof(bid_buf));
 	if (dso__has_build_id(dso))
-		build_id__snprintf(dso__bid_const(dso), bid_buf, sizeof(bid_buf));
+		build_id__snprintf(dso__bid(dso), bid_buf, sizeof(bid_buf));
 	printf("%s %16" PRIx64 " %16" PRIx64, bid_buf, map__start(map), map__end(map));
 	if (dso_long_name != NULL)
 		printf(" %s", dso_long_name);

tools/perf/builtin-inject.c

···
 				struct perf_sample *sample,
 				struct machine *machine)
 {
-	struct dso_id id;
-	struct dso_id *dso_id = NULL;
+	struct dso_id id = dso_id_empty;
 
-	if (!(event->header.misc & PERF_RECORD_MISC_MMAP_BUILD_ID)) {
+	if (event->header.misc & PERF_RECORD_MISC_MMAP_BUILD_ID) {
+		build_id__init(&id.build_id, event->mmap2.build_id, event->mmap2.build_id_size);
+	} else {
 		id.maj = event->mmap2.maj;
 		id.min = event->mmap2.min;
 		id.ino = event->mmap2.ino;
 		id.ino_generation = event->mmap2.ino_generation;
-		dso_id = &id;
+		id.mmap2_valid = true;
+		id.mmap2_ino_generation_valid = true;
 	}
 
 	return perf_event__repipe_common_mmap(
···
 		event->mmap2.pid, event->mmap2.tid,
 		event->mmap2.start, event->mmap2.len, event->mmap2.pgoff,
 		event->mmap2.flags, event->mmap2.prot,
-		event->mmap2.filename, dso_id,
+		event->mmap2.filename, &id,
 		perf_event__process_mmap2);
 }
 
···
 static int dso__read_build_id(struct dso *dso)
 {
 	struct nscookie nsc;
+	struct build_id bid = { .size = 0, };
 
 	if (dso__has_build_id(dso))
 		return 0;
 
 	mutex_lock(dso__lock(dso));
 	nsinfo__mountns_enter(dso__nsinfo(dso), &nsc);
-	if (filename__read_build_id(dso__long_name(dso), dso__bid(dso)) > 0)
-		dso__set_has_build_id(dso);
+	if (filename__read_build_id(dso__long_name(dso), &bid) > 0)
+		dso__set_build_id(dso, &bid);
 	else if (dso__nsinfo(dso)) {
 		char *new_name = dso__filename_with_chroot(dso, dso__long_name(dso));
 
-		if (new_name && filename__read_build_id(new_name, dso__bid(dso)) > 0)
-			dso__set_has_build_id(dso);
+		if (new_name && filename__read_build_id(new_name, &bid) > 0)
+			dso__set_build_id(dso, &bid);
 		free(new_name);
 	}
 	nsinfo__mountns_exit(&nsc);
···
 					       struct dso *dso)
 {
 	struct str_node *pos;
-	int bid_len;
 
 	strlist__for_each_entry(pos, inject->known_build_ids) {
+		struct build_id bid;
 		const char *build_id, *dso_name;
+		size_t bid_len;
 
 		build_id = skip_spaces(pos->s);
 		dso_name = strchr(build_id, ' ');
 		bid_len = dso_name - pos->s;
+		if (bid_len > sizeof(bid.data))
+			bid_len = sizeof(bid.data);
 		dso_name = skip_spaces(dso_name);
 		if (strcmp(dso__long_name(dso), dso_name))
 			continue;
-		for (int ix = 0; 2 * ix + 1 < bid_len; ++ix) {
-			dso__bid(dso)->data[ix] = (hex(build_id[2 * ix]) << 4 |
-						  hex(build_id[2 * ix + 1]));
+		for (size_t ix = 0; 2 * ix + 1 < bid_len; ++ix) {
+			bid.data[ix] = (hex(build_id[2 * ix]) << 4 |
+					hex(build_id[2 * ix + 1]));
 		}
-		dso__bid(dso)->size = bid_len / 2;
-		dso__set_has_build_id(dso);
+		bid.size = bid_len / 2;
+		dso__set_build_id(dso, &bid);
 		return true;
 	}
 	return false;

tools/perf/builtin-report.c

···
 	struct maps__fprintf_task_args *args = data;
 	const struct dso *dso = map__dso(map);
 	u32 prot = map__prot(map);
+	const struct dso_id *dso_id = dso__id_const(dso);
 	int ret;
+	char buf[SBUILD_ID_SIZE];
+
+	if (dso_id->mmap2_valid)
+		snprintf(buf, sizeof(buf), "%" PRIu64, dso_id->ino);
+	else
+		build_id__snprintf(&dso_id->build_id, buf, sizeof(buf));
 
 	ret = fprintf(args->fp,
-		"%*s  %" PRIx64 "-%" PRIx64 " %c%c%c%c %08" PRIx64 " %" PRIu64 " %s\n",
+		"%*s  %" PRIx64 "-%" PRIx64 " %c%c%c%c %08" PRIx64 " %s %s\n",
 		args->indent, "", map__start(map), map__end(map),
 		prot & PROT_READ ? 'r' : '-',
 		prot & PROT_WRITE ? 'w' : '-',
 		prot & PROT_EXEC ? 'x' : '-',
 		map__flags(map) ? 's' : 'p',
 		map__pgoff(map),
-		dso__id_const(dso)->ino, dso__name(dso));
+		buf, dso__name(dso));
 
 	if (ret < 0)
 		return ret;

tools/perf/include/perf/perf_dlfilter.h

···
 	__u8  is_64_bit; /* Only valid if dso is not NULL */
 	__u8  is_kernel_ip; /* True if in kernel space */
 	__u32 buildid_size;
-	__u8 *buildid;
+	const __u8 *buildid;
 	/* Below members are only populated by resolve_ip() */
 	__u8 filtered; /* True if this sample event will be filtered out */
 	const char *comm;

tools/perf/tests/symbols.c

···
 	dso__put(dso);
 
 	/* Create a dummy map at 0x100000 */
-	*map_p = map__new(ti->machine, 0x100000, 0xffffffff, 0, NULL,
-			  PROT_EXEC, 0, NULL, filename, ti->thread);
+	*map_p = map__new(ti->machine, 0x100000, 0xffffffff, 0, &dso_id_empty,
+			  PROT_EXEC, /*flags=*/0, filename, ti->thread);
 	if (!*map_p) {
 		pr_debug("Failed to create map!");
 		return TEST_FAIL;

tools/perf/util/build-id.c

···
 	if (!dso__has_build_id(dso))
 		return NULL;
 
-	build_id__snprintf(dso__bid_const(dso), sbuild_id, sizeof(sbuild_id));
+	build_id__snprintf(dso__bid(dso), sbuild_id, sizeof(sbuild_id));
 	linkname = build_id_cache__linkname(sbuild_id, NULL, 0);
 	if (!linkname)
 		return NULL;
···
 	}
 
 	in_kernel = dso__kernel(dso) || is_kernel_module(name, PERF_RECORD_MISC_CPUMODE_UNKNOWN);
-	return write_buildid(name, name_len, dso__bid(dso), args->machine->pid,
+	return write_buildid(name, name_len, &dso__id(dso)->build_id, args->machine->pid,
 			     in_kernel ? args->kmisc : args->umisc, args->fd);
 }
 

tools/perf/util/dso.c

···
 			break;
 		}
 
-		build_id__snprintf(dso__bid_const(dso), build_id_hex, sizeof(build_id_hex));
+		build_id__snprintf(dso__bid(dso), build_id_hex, sizeof(build_id_hex));
 		len = __symbol__join_symfs(filename, size, "/usr/lib/debug/.build-id/");
 		snprintf(filename + len, size - len, "%.2s/%s.debug",
 			 build_id_hex, build_id_hex + 2);
···
 
 static int __dso_id__cmp(const struct dso_id *a, const struct dso_id *b)
 {
-	if (a->maj > b->maj) return -1;
-	if (a->maj < b->maj) return 1;
+	if (a->mmap2_valid && b->mmap2_valid) {
+		if (a->maj > b->maj) return -1;
+		if (a->maj < b->maj) return 1;
 
-	if (a->min > b->min) return -1;
-	if (a->min < b->min) return 1;
+		if (a->min > b->min) return -1;
+		if (a->min < b->min) return 1;
 
-	if (a->ino > b->ino) return -1;
-	if (a->ino < b->ino) return 1;
-
-	/*
-	 * Synthesized MMAP events have zero ino_generation, avoid comparing
-	 * them with MMAP events with actual ino_generation.
-	 *
-	 * I found it harmful because the mismatch resulted in a new
-	 * dso that did not have a build ID whereas the original dso did have a
-	 * build ID. The build ID was essential because the object was not found
-	 * otherwise. - Adrian
-	 */
-	if (a->ino_generation && b->ino_generation) {
+		if (a->ino > b->ino) return -1;
+		if (a->ino < b->ino) return 1;
+	}
+	if (a->mmap2_ino_generation_valid && b->mmap2_ino_generation_valid) {
 		if (a->ino_generation > b->ino_generation) return -1;
 		if (a->ino_generation < b->ino_generation) return 1;
 	}
-
+	if (build_id__is_defined(&a->build_id) && build_id__is_defined(&b->build_id)) {
+		if (a->build_id.size != b->build_id.size)
+			return a->build_id.size < b->build_id.size ? -1 : 1;
+		return memcmp(a->build_id.data, b->build_id.data, a->build_id.size);
+	}
 	return 0;
 }
 
-bool dso_id__empty(const struct dso_id *id)
-{
-	if (!id)
-		return true;
+const struct dso_id dso_id_empty = {
+	{
+		.maj = 0,
+		.min = 0,
+		.ino = 0,
+		.ino_generation = 0,
+	},
+	.mmap2_valid = false,
+	.mmap2_ino_generation_valid = false,
+	{
+		.size = 0,
+	}
+};
 
-	return !id->maj && !id->min && !id->ino && !id->ino_generation;
-}
-
-void __dso__inject_id(struct dso *dso, const struct dso_id *id)
+void __dso__improve_id(struct dso *dso, const struct dso_id *id)
 {
 	struct dsos *dsos = dso__dsos(dso);
 	struct dso_id *dso_id = dso__id(dso);
+	bool changed = false;
 
 	/* dsos write lock held by caller. */
 
-	dso_id->maj = id->maj;
-	dso_id->min = id->min;
-	dso_id->ino = id->ino;
-	dso_id->ino_generation = id->ino_generation;
-
-	if (dsos)
+	if (id->mmap2_valid && !dso_id->mmap2_valid) {
+		dso_id->maj = id->maj;
+		dso_id->min = id->min;
+		dso_id->ino = id->ino;
+		dso_id->mmap2_valid = true;
+		changed = true;
+	}
+	if (id->mmap2_ino_generation_valid && !dso_id->mmap2_ino_generation_valid) {
+		dso_id->ino_generation = id->ino_generation;
+		dso_id->mmap2_ino_generation_valid = true;
+		changed = true;
+	}
+	if (build_id__is_defined(&id->build_id) && !build_id__is_defined(&dso_id->build_id)) {
+		dso_id->build_id = id->build_id;
+		changed = true;
+	}
+	if (changed && dsos)
 		dsos->sorted = false;
 }
 
 int dso_id__cmp(const struct dso_id *a, const struct dso_id *b)
 {
-	/*
-	 * The second is always dso->id, so zeroes if not set, assume passing
-	 * NULL for a means a zeroed id
-	 */
-	if (dso_id__empty(a) || dso_id__empty(b))
+	if (a == &dso_id_empty || b == &dso_id_empty) {
+		/* There is no valid data to compare so the comparison always returns identical. */
 		return 0;
+	}
 
 	return __dso_id__cmp(a, b);
 }
···
 		dso->loaded = 0;
 		dso->rel = 0;
 		dso->sorted_by_name = 0;
-		dso->has_build_id = 0;
 		dso->has_srcline = 1;
 		dso->a2l_fails = 1;
 		dso->kernel = DSO_SPACE__USER;
···
 	return 0;
 }
 
-void dso__set_build_id(struct dso *dso, struct build_id *bid)
+void dso__set_build_id(struct dso *dso, const struct build_id *bid)
 {
-	RC_CHK_ACCESS(dso)->bid = *bid;
-	RC_CHK_ACCESS(dso)->has_build_id = 1;
+	dso__id(dso)->build_id = *bid;
 }
 
-bool dso__build_id_equal(const struct dso *dso, struct build_id *bid)
+bool dso__build_id_equal(const struct dso *dso, const struct build_id *bid)
 {
-	const struct build_id *dso_bid = dso__bid_const(dso);
+	const struct build_id *dso_bid = dso__bid(dso);
 
 	if (dso_bid->size > bid->size && dso_bid->size == BUILD_ID_SIZE) {
 		/*
···
 void dso__read_running_kernel_build_id(struct dso *dso, struct machine *machine)
 {
 	char path[PATH_MAX];
+	struct build_id bid = { .size = 0, };
 
 	if (machine__is_default_guest(machine))
 		return;
 	sprintf(path, "%s/sys/kernel/notes", machine->root_dir);
-	if (sysfs__read_build_id(path, dso__bid(dso)) == 0)
-		dso__set_has_build_id(dso);
+	sysfs__read_build_id(path, &bid);
+	dso__set_build_id(dso, &bid);
 }
 
 int dso__kernel_module_get_build_id(struct dso *dso,
 				    const char *root_dir)
 {
 	char filename[PATH_MAX];
+	struct build_id bid = { .size = 0, };
 	/*
 	 * kernel module short names are of the form "[module]" and
 	 * we need just "module" here.
···
 		 "%s/sys/module/%.*s/notes/.note.gnu.build-id",
 		 root_dir, (int)strlen(name) - 1, name);
 
-	if (sysfs__read_build_id(filename, dso__bid(dso)) == 0)
-		dso__set_has_build_id(dso);
-
+	sysfs__read_build_id(filename, &bid);
+	dso__set_build_id(dso, &bid);
 	return 0;
 }
 

tools/perf/util/dso.h

···
 #define DSO__DATA_CACHE_SIZE 4096
 #define DSO__DATA_CACHE_MASK ~(DSO__DATA_CACHE_SIZE - 1)
 
-/*
- * Data about backing storage DSO, comes from PERF_RECORD_MMAP2 meta events
+/**
+ * struct dso_id
+ *
+ * Data about backing storage DSO, comes from PERF_RECORD_MMAP2 meta events,
+ * reading from /proc/pid/maps or synthesis of build_ids from DSOs. Possibly
+ * incomplete at any particular use.
  */
 struct dso_id {
-	u32	maj;
-	u32	min;
-	u64	ino;
-	u64	ino_generation;
+	/* Data related to the mmap2 event or read from /proc/pid/maps. */
+	struct {
+		u32	maj;
+		u32	min;
+		u64	ino;
+		u64	ino_generation;
+	};
+	/** @mmap2_valid: Are the maj, min and ino fields valid? */
+	bool	mmap2_valid;
+	/**
+	 * @mmap2_ino_generation_valid: Is the ino_generation valid? Generally
+	 * false for /proc/pid/maps mmap event.
+	 */
+	bool	mmap2_ino_generation_valid;
+	/**
+	 * @build_id: A possibly populated build_id. build_id__is_defined checks
+	 * whether it is populated.
+	 */
+	struct build_id build_id;
 };
 
 struct dso_cache {
···
 		u64		addr;
 		struct symbol	*symbol;
 	} last_find_result;
-	struct build_id	 bid;
 	u64		 text_offset;
 	u64		 text_end;
 	const char	 *short_name;
···
 	enum dso_swap_type	needs_swap:2;
 	bool			is_kmod:1;
 	u8		 adjust_symbols:1;
-	u8		 has_build_id:1;
 	u8		 header_build_id:1;
 	u8		 has_srcline:1;
 	u8		 hit:1;
···
 };
 
 extern struct mutex _dso__data_open_lock;
+extern const struct dso_id dso_id_empty;
+
+int dso_id__cmp(const struct dso_id *a, const struct dso_id *b);
 
 /* dso__for_each_symbol - iterate over the symbols of given type
  *
···
 	RC_CHK_ACCESS(dso)->auxtrace_cache = cache;
 }
 
-static inline struct build_id *dso__bid(struct dso *dso)
-{
-	return &RC_CHK_ACCESS(dso)->bid;
-}
-
-static inline const struct build_id *dso__bid_const(const struct dso *dso)
-{
-	return &RC_CHK_ACCESS(dso)->bid;
-}
-
 static inline struct dso_bpf_prog *dso__bpf_prog(struct dso *dso)
 {
 	return &RC_CHK_ACCESS(dso)->bpf_prog;
-}
-
-static inline bool dso__has_build_id(const struct dso *dso)
-{
-	return RC_CHK_ACCESS(dso)->has_build_id;
-}
-
-static inline void dso__set_has_build_id(struct dso *dso)
-{
-	RC_CHK_ACCESS(dso)->has_build_id = true;
 }
 
 static inline bool dso__has_srcline(const struct dso *dso)
···
 static inline const struct dso_id *dso__id_const(const struct dso *dso)
 {
 	return &RC_CHK_ACCESS(dso)->id;
+}
+
+static inline const struct build_id *dso__bid(const struct dso *dso)
+{
+	return &dso__id_const(dso)->build_id;
+}
+
+static inline bool dso__has_build_id(const struct dso *dso)
+{
+	return build_id__is_defined(dso__bid(dso));
 }
 
 static inline struct rb_root_cached *dso__inlined_nodes(struct dso *dso)
···
 	RC_CHK_ACCESS(dso)->text_offset = val;
 }
 
-int dso_id__cmp(const struct dso_id *a, const struct dso_id *b);
-bool dso_id__empty(const struct dso_id *id);
-
 struct dso *dso__new_id(const char *name, const struct dso_id *id);
 struct dso *dso__new(const char *name);
 void dso__delete(struct dso *dso);
···
 int dso__cmp_id(struct dso *a, struct dso *b);
 void dso__set_short_name(struct dso *dso, const char *name, bool name_allocated);
 void dso__set_long_name(struct dso *dso, const char *name, bool name_allocated);
-void __dso__inject_id(struct dso *dso, const struct dso_id *id);
+void __dso__improve_id(struct dso *dso, const struct dso_id *id);
 
 int dso__name_len(const struct dso *dso);
 
···
 
 int dso__swap_init(struct dso *dso, unsigned char eidata);
 
-void dso__set_build_id(struct dso *dso, struct build_id *bid);
-bool dso__build_id_equal(const struct dso *dso, struct build_id *bid);
+void dso__set_build_id(struct dso *dso, const struct build_id *bid);
+bool dso__build_id_equal(const struct dso *dso, const struct build_id *bid);
 void dso__read_running_kernel_build_id(struct dso *dso,
 				       struct machine *machine);
 int dso__kernel_module_get_build_id(struct dso *dso, const char *root_dir);

tools/perf/util/dsos.c

···
 {
 	struct dsos__read_build_ids_cb_args *args = data;
 	struct nscookie nsc;
+	struct build_id bid = { .size = 0, };
 
 	if (args->with_hits && !dso__hit(dso) && !dso__is_vdso(dso))
 		return 0;
···
 		return 0;
 	}
 	nsinfo__mountns_enter(dso__nsinfo(dso), &nsc);
-	if (filename__read_build_id(dso__long_name(dso), dso__bid(dso)) > 0) {
+	if (filename__read_build_id(dso__long_name(dso), &bid) > 0) {
+		dso__set_build_id(dso, &bid);
 		args->have_build_id = true;
-		dso__set_has_build_id(dso);
 	} else if (errno == ENOENT && dso__nsinfo(dso)) {
 		char *new_name = dso__filename_with_chroot(dso, dso__long_name(dso));
 
-		if (new_name && filename__read_build_id(new_name, dso__bid(dso)) > 0) {
+		if (new_name && filename__read_build_id(new_name, &bid) > 0) {
+			dso__set_build_id(dso, &bid);
 			args->have_build_id = true;
-			dso__set_has_build_id(dso);
 		}
 		free(new_name);
 	}
···
 	struct dso *res;
 
 	down_read(&dsos->lock);
-	res = __dsos__find_id(dsos, name, NULL, cmp_short, /*write_locked=*/false);
+	res = __dsos__find_id(dsos, name, &dso_id_empty, cmp_short, /*write_locked=*/false);
 	up_read(&dsos->lock);
 	return res;
 }
···
 {
 	struct dso *dso = __dsos__find_id(dsos, name, id, false, /*write_locked=*/true);
 
-	if (dso && dso_id__empty(dso__id(dso)) && !dso_id__empty(id))
-		__dso__inject_id(dso, id);
+	if (dso)
+		__dso__improve_id(dso, id);
 
 	return dso ? dso : __dsos__addnew_id(dsos, name, id);
 }
···
 
 	down_write(&dsos->lock);
 
-	dso = __dsos__find_id(dsos, m->name, NULL, /*cmp_short=*/true, /*write_locked=*/true);
+	dso = __dsos__find_id(dsos, m->name, &dso_id_empty, /*cmp_short=*/true,
+			      /*write_locked=*/true);
 	if (dso) {
 		up_write(&dsos->lock);
 		return dso;

tools/perf/util/machine.c

···
 {
 	struct thread *thread;
 	struct map *map;
-	struct dso_id dso_id = {
-		.maj = event->mmap2.maj,
-		.min = event->mmap2.min,
-		.ino = event->mmap2.ino,
-		.ino_generation = event->mmap2.ino_generation,
-	};
-	struct build_id __bid, *bid = NULL;
+	struct dso_id dso_id = dso_id_empty;
 	int ret = 0;
 
 	if (dump_trace)
 		perf_event__fprintf_mmap2(event, stdout);
 
 	if (event->header.misc & PERF_RECORD_MISC_MMAP_BUILD_ID) {
-		bid = &__bid;
-		build_id__init(bid, event->mmap2.build_id, event->mmap2.build_id_size);
+		build_id__init(&dso_id.build_id, event->mmap2.build_id, event->mmap2.build_id_size);
+	} else {
+		dso_id.maj = event->mmap2.maj;
+		dso_id.min = event->mmap2.min;
+		dso_id.ino = event->mmap2.ino;
+		dso_id.ino_generation = event->mmap2.ino_generation;
+		dso_id.mmap2_valid = true;
+		dso_id.mmap2_ino_generation_valid = true;
 	}
 
 	if (sample->cpumode == PERF_RECORD_MISC_GUEST_KERNEL ||
···
 		};
 
 		strlcpy(xm.name, event->mmap2.filename, KMAP_NAME_LEN);
-		ret = machine__process_kernel_mmap_event(machine, &xm, bid);
+		ret = machine__process_kernel_mmap_event(machine, &xm, &dso_id.build_id);
 		if (ret < 0)
 			goto out_problem;
 		return 0;
···
 	map = map__new(machine, event->mmap2.start,
 			event->mmap2.len, event->mmap2.pgoff,
 			&dso_id, event->mmap2.prot,
-			event->mmap2.flags, bid,
+			event->mmap2.flags,
 			event->mmap2.filename, thread);
 
 	if (map == NULL)
···
 		prot = PROT_EXEC;
 
 	map = map__new(machine, event->mmap.start,
-			event->mmap.len, event->mmap.pgoff,
-			NULL, prot, 0, NULL, event->mmap.filename, thread);
+		       event->mmap.len, event->mmap.pgoff,
+		       &dso_id_empty, prot, /*flags=*/0, event->mmap.filename, thread);
 
 	if (map == NULL)
 		goto out_problem_map;
···
 
 struct dso *machine__findnew_dso(struct machine *machine, const char *filename)
 {
-	return machine__findnew_dso_id(machine, filename, NULL);
+	return machine__findnew_dso_id(machine, filename, &dso_id_empty);
 }
 
 char *machine__resolve_kernel_addr(void *vmachine, unsigned long long *addrp, char **modp)

tools/perf/util/map.c

···
 }
 
 struct map *map__new(struct machine *machine, u64 start, u64 len,
-		     u64 pgoff, struct dso_id *id,
-		     u32 prot, u32 flags, struct build_id *bid,
+		     u64 pgoff, const struct dso_id *id,
+		     u32 prot, u32 flags,
 		     char *filename, struct thread *thread)
 {
 	struct map *result;
···
 	map = zalloc(sizeof(*map));
 	if (ADD_RC_CHK(result, map)) {
 		char newfilename[PATH_MAX];
-		struct dso *dso, *header_bid_dso;
+		struct dso *dso;
 		int anon, no_dso, vdso, android;
 
 		android = is_android_lib(filename);
···
 		dso__set_nsinfo(dso, nsi);
 		mutex_unlock(dso__lock(dso));
 
-		if (build_id__is_defined(bid)) {
-			dso__set_build_id(dso, bid);
-		} else {
+		if (!build_id__is_defined(&id->build_id)) {
 			/*
 			 * If the mmap event had no build ID, search for an existing dso from the
 			 * build ID header by name. Otherwise only the dso loaded at the time of
 			 * reading the header will have the build ID set and all future mmaps will
 			 * have it missing.
 			 */
-			header_bid_dso = dsos__find(&machine->dsos, filename, false);
+			struct dso *header_bid_dso = dsos__find(&machine->dsos, filename, false);
+
 			if (header_bid_dso && dso__header_build_id(header_bid_dso)) {
 				dso__set_build_id(dso, dso__bid(header_bid_dso));
 				dso__set_header_build_id(dso, 1);

tools/perf/util/map.h

···
 	__map__for_each_symbol_by_name(map, sym_name, (pos), idx)
 
 struct dso_id;
-struct build_id;
 
 struct map *map__new(struct machine *machine, u64 start, u64 len,
-		     u64 pgoff, struct dso_id *id, u32 prot, u32 flags,
-		     struct build_id *bid, char *filename, struct thread *thread);
+		     u64 pgoff, const struct dso_id *id, u32 prot, u32 flags,
+		     char *filename, struct thread *thread);
 struct map *map__new2(u64 start, struct dso *dso);
 void map__delete(struct map *map);
 struct map *map__clone(struct map *map);

tools/perf/util/sort.c

···
 	if (rc)
 		return rc;
 	/*
-	 * Addresses with no major/minor numbers are assumed to be
+	 * Addresses with no major/minor numbers or build ID are assumed to be
 	 * anonymous in userspace.  Sort those on pid then address.
 	 *
 	 * The kernel and non-zero major/minor mapped areas are
 	 * assumed to be unity mapped.  Sort those on address.
 	 */
+	if (left->cpumode != PERF_RECORD_MISC_KERNEL && (map__flags(l_map) & MAP_SHARED) == 0) {
+		const struct dso_id *dso_id = dso__id_const(l_dso);
 
-	if ((left->cpumode != PERF_RECORD_MISC_KERNEL) &&
-	    (!(map__flags(l_map) & MAP_SHARED)) && !dso__id(l_dso)->maj && !dso__id(l_dso)->min &&
-	     !dso__id(l_dso)->ino && !dso__id(l_dso)->ino_generation) {
-		/* userspace anonymous */
+		if (!dso_id->mmap2_valid)
+			dso_id = dso__id_const(r_dso);
 
-		if (thread__pid(left->thread) > thread__pid(right->thread))
-			return -1;
-		if (thread__pid(left->thread) < thread__pid(right->thread))
-			return 1;
+		if (!build_id__is_defined(&dso_id->build_id) &&
+		    (!dso_id->mmap2_valid || (dso_id->maj == 0 && dso_id->min == 0))) {
+			/* userspace anonymous */
+
+			if (thread__pid(left->thread) > thread__pid(right->thread))
+				return -1;
+			if (thread__pid(left->thread) < thread__pid(right->thread))
+				return 1;
+		}
 	}
 
 addr:
···
 	if (he->mem_info) {
 		struct map *map = mem_info__daddr(he->mem_info)->ms.map;
 		struct dso *dso = map ? map__dso(map) : NULL;
+		const struct dso_id *dso_id = dso ? dso__id_const(dso) : &dso_id_empty;
 
 		addr = cl_address(mem_info__daddr(he->mem_info)->al_addr, chk_double_cl);
 		ms = &mem_info__daddr(he->mem_info)->ms;
···
 		if ((he->cpumode != PERF_RECORD_MISC_KERNEL) &&
 		     map && !(map__prot(map) & PROT_EXEC) &&
 		     (map__flags(map) & MAP_SHARED) &&
-		     (dso__id(dso)->maj || dso__id(dso)->min || dso__id(dso)->ino ||
-		      dso__id(dso)->ino_generation))
+		     (!dso_id->mmap2_valid || (dso_id->maj == 0 && dso_id->min == 0)))
 			level = 's';
 		else if (!map)
 			level = 'X';

tools/perf/util/synthetic-events.c

···
 	struct nsinfo *nsi;
 	struct nscookie nc;
 	struct dso *dso = NULL;
-	struct dso_id id;
+	struct dso_id dso_id = dso_id_empty;
 	int rc;
 
 	if (is_kernel) {
···
 		goto out;
 	}
 
-	id.maj = event->maj;
-	id.min = event->min;
-	id.ino = event->ino;
-	id.ino_generation = event->ino_generation;
+	if (event->header.misc & PERF_RECORD_MISC_MMAP_BUILD_ID) {
+		build_id__init(&dso_id.build_id, event->build_id, event->build_id_size);
+	} else {
+		dso_id.maj = event->maj;
+		dso_id.min = event->min;
+		dso_id.ino = event->ino;
+		dso_id.ino_generation = event->ino_generation;
+		dso_id.mmap2_valid = true;
+		dso_id.mmap2_ino_generation_valid = true;
+	};
 
-	dso = dsos__findnew_id(&machine->dsos, event->filename, &id);
+	dso = dsos__findnew_id(&machine->dsos, event->filename, &dso_id);
 	if (dso && dso__has_build_id(dso)) {
 		bid = *dso__bid(dso);
 		rc = 0;