perf: 'perf kvm' tool for monitoring guest performance from host

Here is the patch of userspace perf tool.

Signed-off-by: Zhang Yanmin <yanmin_zhang@linux.intel.com>
Signed-off-by: Avi Kivity <avi@redhat.com>

1 files changed, 317 insertions, 65 deletions

diff --git a/tools/perf/util/symbol.c b/tools/perf/util/symbol.c
index f3d4151..e782e7d 100644
--- a/tools/perf/util/symbol.c
+++ b/tools/perf/util/symbol.c
@@ -28,6 +28,8 @@ static void dsos__add(struct list_head *head, struct dso *dso);
 static struct map *map__new2(u64 start, struct dso *dso, enum map_type type);
 static int dso__load_kernel_sym(struct dso *self, struct map *map,
 				symbol_filter_t filter);
+static int dso__load_guest_kernel_sym(struct dso *self, struct map *map,
+			symbol_filter_t filter);
 static int vmlinux_path__nr_entries;
 static char **vmlinux_path;
 
@@ -186,6 +188,7 @@ struct dso *dso__new(const char *name)
 		self->loaded = 0;
 		self->sorted_by_name = 0;
 		self->has_build_id = 0;
+		self->kernel = DSO_TYPE_USER;
 	}
 
 	return self;
@@ -402,12 +405,9 @@ int kallsyms__parse(const char *filename, void *arg,
 		char *symbol_name;
 
 		line_len = getline(&line, &n, file);
-		if (line_len < 0)
+		if (line_len < 0 || !line)
 			break;
 
-		if (!line)
-			goto out_failure;
-
 		line[--line_len] = '\0'; /* \n */
 
 		len = hex2u64(line, &start);
@@ -459,6 +459,7 @@ static int map__process_kallsym_symbol(void *arg, const char *name,
 	 * map__split_kallsyms, when we have split the maps per module
 	 */
 	symbols__insert(root, sym);
+
 	return 0;
 }
 
@@ -483,6 +484,7 @@ static int dso__split_kallsyms(struct dso *self, struct map *map,
 			       symbol_filter_t filter)
 {
 	struct map_groups *kmaps = map__kmap(map)->kmaps;
+	struct kernel_info *kerninfo = kmaps->this_kerninfo;
 	struct map *curr_map = map;
 	struct symbol *pos;
 	int count = 0;
@@ -504,15 +506,33 @@ static int dso__split_kallsyms(struct dso *self, struct map *map,
 			*module++ = '\0';
 
 			if (strcmp(curr_map->dso->short_name, module)) {
-				curr_map = map_groups__find_by_name(kmaps, map->type, module);
+				if (curr_map != map &&
+					self->kernel == DSO_TYPE_GUEST_KERNEL &&
+					is_default_guest(kerninfo)) {
+					/*
+					 * We assume all symbols of a module are
+					 * continuous in * kallsyms, so curr_map
+					 * points to a module and all its
+					 * symbols are in its kmap. Mark it as
+					 * loaded.
+					 */
+					dso__set_loaded(curr_map->dso,
+							curr_map->type);
+				}
+
+				curr_map = map_groups__find_by_name(kmaps,
+							map->type, module);
 				if (curr_map == NULL) {
-					pr_debug("/proc/{kallsyms,modules} "
+					pr_err("%s/proc/{kallsyms,modules} "
 					         "inconsistency while looking "
-						 "for \"%s\" module!\n", module);
-					return -1;
+						 "for \"%s\" module!\n",
+						 kerninfo->root_dir, module);
+					curr_map = map;
+					goto discard_symbol;
 				}
 
-				if (curr_map->dso->loaded)
+				if (curr_map->dso->loaded &&
+					!is_default_guest(kmaps->this_kerninfo))
 					goto discard_symbol;
 			}
 			/*
@@ -525,13 +545,21 @@ static int dso__split_kallsyms(struct dso *self, struct map *map,
 			char dso_name[PATH_MAX];
 			struct dso *dso;
 
-			snprintf(dso_name, sizeof(dso_name), "[kernel].%d",
-				 kernel_range++);
+			if (self->kernel == DSO_TYPE_GUEST_KERNEL)
+				snprintf(dso_name, sizeof(dso_name),
+					"[guest.kernel].%d",
+					kernel_range++);
+			else
+				snprintf(dso_name, sizeof(dso_name),
+					"[kernel].%d",
+					kernel_range++);
 
 			dso = dso__new(dso_name);
 			if (dso == NULL)
 				return -1;
 
+			dso->kernel = self->kernel;
+
 			curr_map = map__new2(pos->start, dso, map->type);
 			if (curr_map == NULL) {
 				dso__delete(dso);
@@ -555,6 +583,12 @@ discard_symbol:		rb_erase(&pos->rb_node, root);
 		}
 	}
 
+	if (curr_map != map &&
+	    self->kernel == DSO_TYPE_GUEST_KERNEL &&
+	    is_default_guest(kmaps->this_kerninfo)) {
+		dso__set_loaded(curr_map->dso, curr_map->type);
+	}
+
 	return count;
 }
 
@@ -565,7 +599,10 @@ int dso__load_kallsyms(struct dso *self, const char *filename,
 		return -1;
 
 	symbols__fixup_end(&self->symbols[map->type]);
-	self->origin = DSO__ORIG_KERNEL;
+	if (self->kernel == DSO_TYPE_GUEST_KERNEL)
+		self->origin = DSO__ORIG_GUEST_KERNEL;
+	else
+		self->origin = DSO__ORIG_KERNEL;
 
 	return dso__split_kallsyms(self, map, filter);
 }
@@ -952,7 +989,7 @@ static int dso__load_sym(struct dso *self, struct map *map, const char *name,
 	nr_syms = shdr.sh_size / shdr.sh_entsize;
 
 	memset(&sym, 0, sizeof(sym));
-	if (!self->kernel) {
+	if (self->kernel == DSO_TYPE_USER) {
 		self->adjust_symbols = (ehdr.e_type == ET_EXEC ||
 				elf_section_by_name(elf, &ehdr, &shdr,
 						     ".gnu.prelink_undo",
@@ -984,7 +1021,7 @@ static int dso__load_sym(struct dso *self, struct map *map, const char *name,
 
 		section_name = elf_sec__name(&shdr, secstrs);
 
-		if (self->kernel || kmodule) {
+		if (self->kernel != DSO_TYPE_USER || kmodule) {
 			char dso_name[PATH_MAX];
 
 			if (strcmp(section_name,
@@ -1011,6 +1048,7 @@ static int dso__load_sym(struct dso *self, struct map *map, const char *name,
 				curr_dso = dso__new(dso_name);
 				if (curr_dso == NULL)
 					goto out_elf_end;
+				curr_dso->kernel = self->kernel;
 				curr_map = map__new2(start, curr_dso,
 						     map->type);
 				if (curr_map == NULL) {
@@ -1021,7 +1059,7 @@ static int dso__load_sym(struct dso *self, struct map *map, const char *name,
 				curr_map->unmap_ip = identity__map_ip;
 				curr_dso->origin = self->origin;
 				map_groups__insert(kmap->kmaps, curr_map);
-				dsos__add(&dsos__kernel, curr_dso);
+				dsos__add(&self->node, curr_dso);
 				dso__set_loaded(curr_dso, map->type);
 			} else
 				curr_dso = curr_map->dso;
@@ -1083,7 +1121,7 @@ static bool dso__build_id_equal(const struct dso *self, u8 *build_id)
 	return memcmp(self->build_id, build_id, sizeof(self->build_id)) == 0;
 }
 
-static bool __dsos__read_build_ids(struct list_head *head, bool with_hits)
+bool __dsos__read_build_ids(struct list_head *head, bool with_hits)
 {
 	bool have_build_id = false;
 	struct dso *pos;
@@ -1101,13 +1139,6 @@ static bool __dsos__read_build_ids(struct list_head *head, bool with_hits)
 	return have_build_id;
 }
 
-bool dsos__read_build_ids(bool with_hits)
-{
-	bool kbuildids = __dsos__read_build_ids(&dsos__kernel, with_hits),
-	     ubuildids = __dsos__read_build_ids(&dsos__user, with_hits);
-	return kbuildids || ubuildids;
-}
-
 /*
  * Align offset to 4 bytes as needed for note name and descriptor data.
  */
@@ -1242,6 +1273,8 @@ char dso__symtab_origin(const struct dso *self)
 		[DSO__ORIG_BUILDID] =  'b',
 		[DSO__ORIG_DSO] =      'd',
 		[DSO__ORIG_KMODULE] =  'K',
+		[DSO__ORIG_GUEST_KERNEL] =  'g',
+		[DSO__ORIG_GUEST_KMODULE] =  'G',
 	};
 
 	if (self == NULL || self->origin == DSO__ORIG_NOT_FOUND)
@@ -1257,11 +1290,20 @@ int dso__load(struct dso *self, struct map *map, symbol_filter_t filter)
 	char build_id_hex[BUILD_ID_SIZE * 2 + 1];
 	int ret = -1;
 	int fd;
+	struct kernel_info *kerninfo;
+	const char *root_dir;
 
 	dso__set_loaded(self, map->type);
 
-	if (self->kernel)
+	if (self->kernel == DSO_TYPE_KERNEL)
 		return dso__load_kernel_sym(self, map, filter);
+	else if (self->kernel == DSO_TYPE_GUEST_KERNEL)
+		return dso__load_guest_kernel_sym(self, map, filter);
+
+	if (map->groups && map->groups->this_kerninfo)
+		kerninfo = map->groups->this_kerninfo;
+	else
+		kerninfo = NULL;
 
 	name = malloc(size);
 	if (!name)
@@ -1315,6 +1357,13 @@ more:
 		case DSO__ORIG_DSO:
 			snprintf(name, size, "%s", self->long_name);
 			break;
+		case DSO__ORIG_GUEST_KMODULE:
+			if (map->groups && map->groups->this_kerninfo)
+				root_dir = map->groups->this_kerninfo->root_dir;
+			else
+				root_dir = "";
+			snprintf(name, size, "%s%s", root_dir, self->long_name);
+			break;
 
 		default:
 			goto out;
@@ -1368,7 +1417,8 @@ struct map *map_groups__find_by_name(struct map_groups *self,
 	return NULL;
 }
 
-static int dso__kernel_module_get_build_id(struct dso *self)
+static int dso__kernel_module_get_build_id(struct dso *self,
+				const char *root_dir)
 {
 	char filename[PATH_MAX];
 	/*
@@ -1378,8 +1428,8 @@ static int dso__kernel_module_get_build_id(struct dso *self)
 	const char *name = self->short_name + 1;
 
 	snprintf(filename, sizeof(filename),
-		 "/sys/module/%.*s/notes/.note.gnu.build-id",
-		 (int)strlen(name - 1), name);
+		 "%s/sys/module/%.*s/notes/.note.gnu.build-id",
+		 root_dir, (int)strlen(name) - 1, name);
 
 	if (sysfs__read_build_id(filename, self->build_id,
 				 sizeof(self->build_id)) == 0)
@@ -1388,7 +1438,8 @@ static int dso__kernel_module_get_build_id(struct dso *self)
 	return 0;
 }
 
-static int map_groups__set_modules_path_dir(struct map_groups *self, char *dir_name)
+static int map_groups__set_modules_path_dir(struct map_groups *self,
+				const char *dir_name)
 {
 	struct dirent *dent;
 	DIR *dir = opendir(dir_name);
@@ -1400,8 +1451,14 @@ static int map_groups__set_modules_path_dir(struct map_groups *self, char *dir_n
 
 	while ((dent = readdir(dir)) != NULL) {
 		char path[PATH_MAX];
+		struct stat st;
+
+		/*sshfs might return bad dent->d_type, so we have to stat*/
+		sprintf(path, "%s/%s", dir_name, dent->d_name);
+		if (stat(path, &st))
+			continue;
 
-		if (dent->d_type == DT_DIR) {
+		if (S_ISDIR(st.st_mode)) {
 			if (!strcmp(dent->d_name, ".") ||
 			    !strcmp(dent->d_name, ".."))
 				continue;
@@ -1433,7 +1490,7 @@ static int map_groups__set_modules_path_dir(struct map_groups *self, char *dir_n
 			if (long_name == NULL)
 				goto failure;
 			dso__set_long_name(map->dso, long_name);
-			dso__kernel_module_get_build_id(map->dso);
+			dso__kernel_module_get_build_id(map->dso, "");
 		}
 	}
 
@@ -1443,16 +1500,46 @@ failure:
 	return -1;
 }
 
-static int map_groups__set_modules_path(struct map_groups *self)
+static char *get_kernel_version(const char *root_dir)
 {
-	struct utsname uts;
+	char version[PATH_MAX];
+	FILE *file;
+	char *name, *tmp;
+	const char *prefix = "Linux version ";
+
+	sprintf(version, "%s/proc/version", root_dir);
+	file = fopen(version, "r");
+	if (!file)
+		return NULL;
+
+	version[0] = '\0';
+	tmp = fgets(version, sizeof(version), file);
+	fclose(file);
+
+	name = strstr(version, prefix);
+	if (!name)
+		return NULL;
+	name += strlen(prefix);
+	tmp = strchr(name, ' ');
+	if (tmp)
+		*tmp = '\0';
+
+	return strdup(name);
+}
+
+static int map_groups__set_modules_path(struct map_groups *self,
+				const char *root_dir)
+{
+	char *version;
 	char modules_path[PATH_MAX];
 
-	if (uname(&uts) < 0)
+	version = get_kernel_version(root_dir);
+	if (!version)
 		return -1;
 
-	snprintf(modules_path, sizeof(modules_path), "/lib/modules/%s/kernel",
-		 uts.release);
+	snprintf(modules_path, sizeof(modules_path), "%s/lib/modules/%s/kernel",
+		 root_dir, version);
+	free(version);
 
 	return map_groups__set_modules_path_dir(self, modules_path);
 }
@@ -1477,11 +1564,13 @@ static struct map *map__new2(u64 start, struct dso *dso, enum map_type type)
 }
 
 struct map *map_groups__new_module(struct map_groups *self, u64 start,
-				   const char *filename)
+				const char *filename,
+				struct kernel_info *kerninfo)
 {
 	struct map *map;
-	struct dso *dso = __dsos__findnew(&dsos__kernel, filename);
+	struct dso *dso;
 
+	dso = __dsos__findnew(&kerninfo->dsos__kernel, filename);
 	if (dso == NULL)
 		return NULL;
 
@@ -1489,21 +1578,37 @@ struct map *map_groups__new_module(struct map_groups *self, u64 start,
 	if (map == NULL)
 		return NULL;
 
-	dso->origin = DSO__ORIG_KMODULE;
+	if (is_host_kernel(kerninfo))
+		dso->origin = DSO__ORIG_KMODULE;
+	else
+		dso->origin = DSO__ORIG_GUEST_KMODULE;
 	map_groups__insert(self, map);
 	return map;
 }
 
-static int map_groups__create_modules(struct map_groups *self)
+static int map_groups__create_modules(struct kernel_info *kerninfo)
 {
 	char *line = NULL;
 	size_t n;
-	FILE *file = fopen("/proc/modules", "r");
+	FILE *file;
 	struct map *map;
+	const char *root_dir;
+	const char *modules;
+	char path[PATH_MAX];
+
+	if (is_default_guest(kerninfo))
+		modules = symbol_conf.default_guest_modules;
+	else {
+		sprintf(path, "%s/proc/modules", kerninfo->root_dir);
+		modules = path;
+	}
 
+	file = fopen(modules, "r");
 	if (file == NULL)
 		return -1;
 
+	root_dir = kerninfo->root_dir;
+
 	while (!feof(file)) {
 		char name[PATH_MAX];
 		u64 start;
@@ -1532,16 +1637,17 @@ static int map_groups__create_modules(struct map_groups *self)
 		*sep = '\0';
 
 		snprintf(name, sizeof(name), "[%s]", line);
-		map = map_groups__new_module(self, start, name);
+		map = map_groups__new_module(&kerninfo->kmaps,
+				start, name, kerninfo);
 		if (map == NULL)
 			goto out_delete_line;
-		dso__kernel_module_get_build_id(map->dso);
+		dso__kernel_module_get_build_id(map->dso, root_dir);
 	}
 
 	free(line);
 	fclose(file);
 
-	return map_groups__set_modules_path(self);
+	return map_groups__set_modules_path(&kerninfo->kmaps, root_dir);
 
 out_delete_line:
 	free(line);
@@ -1708,8 +1814,57 @@ out_fixup:
 	return err;
 }
 
-LIST_HEAD(dsos__user);
-LIST_HEAD(dsos__kernel);
+static int dso__load_guest_kernel_sym(struct dso *self, struct map *map,
+				symbol_filter_t filter)
+{
+	int err;
+	const char *kallsyms_filename = NULL;
+	struct kernel_info *kerninfo;
+	char path[PATH_MAX];
+
+	if (!map->groups) {
+		pr_debug("Guest kernel map hasn't the point to groups\n");
+		return -1;
+	}
+	kerninfo = map->groups->this_kerninfo;
+
+	if (is_default_guest(kerninfo)) {
+		/*
+		 * if the user specified a vmlinux filename, use it and only
+		 * it, reporting errors to the user if it cannot be used.
+		 * Or use file guest_kallsyms inputted by user on commandline
+		 */
+		if (symbol_conf.default_guest_vmlinux_name != NULL) {
+			err = dso__load_vmlinux(self, map,
+				symbol_conf.default_guest_vmlinux_name, filter);
+			goto out_try_fixup;
+		}
+
+		kallsyms_filename = symbol_conf.default_guest_kallsyms;
+		if (!kallsyms_filename)
+			return -1;
+	} else {
+		sprintf(path, "%s/proc/kallsyms", kerninfo->root_dir);
+		kallsyms_filename = path;
+	}
+
+	err = dso__load_kallsyms(self, kallsyms_filename, map, filter);
+	if (err > 0)
+		pr_debug("Using %s for symbols\n", kallsyms_filename);
+
+out_try_fixup:
+	if (err > 0) {
+		if (kallsyms_filename != NULL) {
+			kern_mmap_name(kerninfo, path);
+			dso__set_long_name(self,
+				strdup(path));
+		}
+		map__fixup_start(map);
+		map__fixup_end(map);
+	}
+
+	return err;
+}
 
 static void dsos__add(struct list_head *head, struct dso *dso)
 {
@@ -1752,10 +1907,16 @@ static void __dsos__fprintf(struct list_head *head, FILE *fp)
 	}
 }
 
-void dsos__fprintf(FILE *fp)
+void dsos__fprintf(struct rb_root *kerninfo_root, FILE *fp)
 {
-	__dsos__fprintf(&dsos__kernel, fp);
-	__dsos__fprintf(&dsos__user, fp);
+	struct rb_node *nd;
+
+	for (nd = rb_first(kerninfo_root); nd; nd = rb_next(nd)) {
+		struct kernel_info *pos = rb_entry(nd, struct kernel_info,
+				rb_node);
+		__dsos__fprintf(&pos->dsos__kernel, fp);
+		__dsos__fprintf(&pos->dsos__user, fp);
+	}
 }
 
 static size_t __dsos__fprintf_buildid(struct list_head *head, FILE *fp,
@@ -1773,10 +1934,21 @@ static size_t __dsos__fprintf_buildid(struct list_head *head, FILE *fp,
 	return ret;
 }
 
-size_t dsos__fprintf_buildid(FILE *fp, bool with_hits)
+size_t dsos__fprintf_buildid(struct rb_root *kerninfo_root,
+		FILE *fp, bool with_hits)
 {
-	return (__dsos__fprintf_buildid(&dsos__kernel, fp, with_hits) +
-		__dsos__fprintf_buildid(&dsos__user, fp, with_hits));
+	struct rb_node *nd;
+	size_t ret = 0;
+
+	for (nd = rb_first(kerninfo_root); nd; nd = rb_next(nd)) {
+		struct kernel_info *pos = rb_entry(nd, struct kernel_info,
+				rb_node);
+		ret += __dsos__fprintf_buildid(&pos->dsos__kernel,
+					fp, with_hits);
+		ret += __dsos__fprintf_buildid(&pos->dsos__user,
+					fp, with_hits);
+	}
+	return ret;
 }
 
 struct dso *dso__new_kernel(const char *name)
@@ -1785,28 +1957,59 @@ struct dso *dso__new_kernel(const char *name)
 
 	if (self != NULL) {
 		dso__set_short_name(self, "[kernel]");
-		self->kernel	 = 1;
+		self->kernel = DSO_TYPE_KERNEL;
+	}
+
+	return self;
+}
+
+static struct dso *dso__new_guest_kernel(struct kernel_info *kerninfo,
+					const char *name)
+{
+	char buff[PATH_MAX];
+	struct dso *self;
+
+	kern_mmap_name(kerninfo, buff);
+	self = dso__new(name ?: buff);
+	if (self != NULL) {
+		dso__set_short_name(self, "[guest.kernel]");
+		self->kernel = DSO_TYPE_GUEST_KERNEL;
 	}
 
 	return self;
 }
 
-void dso__read_running_kernel_build_id(struct dso *self)
+void dso__read_running_kernel_build_id(struct dso *self,
+			struct kernel_info *kerninfo)
 {
-	if (sysfs__read_build_id("/sys/kernel/notes", self->build_id,
+	char path[PATH_MAX];
+
+	if (is_default_guest(kerninfo))
+		return;
+	sprintf(path, "%s/sys/kernel/notes", kerninfo->root_dir);
+	if (sysfs__read_build_id(path, self->build_id,
 				 sizeof(self->build_id)) == 0)
 		self->has_build_id = true;
 }
 
-static struct dso *dsos__create_kernel(const char *vmlinux)
+static struct dso *dsos__create_kernel(struct kernel_info *kerninfo)
 {
-	struct dso *kernel = dso__new_kernel(vmlinux);
+	const char *vmlinux_name = NULL;
+	struct dso *kernel;
 
-	if (kernel != NULL) {
-		dso__read_running_kernel_build_id(kernel);
-		dsos__add(&dsos__kernel, kernel);
+	if (is_host_kernel(kerninfo)) {
+		vmlinux_name = symbol_conf.vmlinux_name;
+		kernel = dso__new_kernel(vmlinux_name);
+	} else {
+		if (is_default_guest(kerninfo))
+			vmlinux_name = symbol_conf.default_guest_vmlinux_name;
+		kernel = dso__new_guest_kernel(kerninfo, vmlinux_name);
 	}
 
+	if (kernel != NULL) {
+		dso__read_running_kernel_build_id(kernel, kerninfo);
+		dsos__add(&kerninfo->dsos__kernel, kernel);
+	}
 	return kernel;
 }
 
@@ -1950,23 +2153,29 @@ out_free_comm_list:
 	return -1;
 }
 
-int map_groups__create_kernel_maps(struct map_groups *self,
-				   struct map *vmlinux_maps[MAP__NR_TYPES])
+int map_groups__create_kernel_maps(struct rb_root *kerninfo_root, pid_t pid)
 {
-	struct dso *kernel = dsos__create_kernel(symbol_conf.vmlinux_name);
+	struct kernel_info *kerninfo;
+	struct dso *kernel;
 
+	kerninfo = kerninfo__findnew(kerninfo_root, pid);
+	if (kerninfo == NULL)
+		return -1;
+	kernel = dsos__create_kernel(kerninfo);
 	if (kernel == NULL)
 		return -1;
 
-	if (__map_groups__create_kernel_maps(self, vmlinux_maps, kernel) < 0)
+	if (__map_groups__create_kernel_maps(&kerninfo->kmaps,
+			kerninfo->vmlinux_maps, kernel) < 0)
 		return -1;
 
-	if (symbol_conf.use_modules && map_groups__create_modules(self) < 0)
+	if (symbol_conf.use_modules &&
+		map_groups__create_modules(kerninfo) < 0)
 		pr_debug("Problems creating module maps, continuing anyway...\n");
 	/*
 	 * Now that we have all the maps created, just set the ->end of them:
 	 */
-	map_groups__fixup_end(self);
+	map_groups__fixup_end(&kerninfo->kmaps);
 	return 0;
 }
 
@@ -2012,3 +2221,46 @@ char *strxfrchar(char *s, char from, char to)
 
 	return s;
 }
+
+int map_groups__create_guest_kernel_maps(struct rb_root *kerninfo_root)
+{
+	int ret = 0;
+	struct dirent **namelist = NULL;
+	int i, items = 0;
+	char path[PATH_MAX];
+	pid_t pid;
+
+	if (symbol_conf.default_guest_vmlinux_name ||
+	    symbol_conf.default_guest_modules ||
+	    symbol_conf.default_guest_kallsyms) {
+		map_groups__create_kernel_maps(kerninfo_root,
+					DEFAULT_GUEST_KERNEL_ID);
+	}
+
+	if (symbol_conf.guestmount) {
+		items = scandir(symbol_conf.guestmount, &namelist, NULL, NULL);
+		if (items <= 0)
+			return -ENOENT;
+		for (i = 0; i < items; i++) {
+			if (!isdigit(namelist[i]->d_name[0])) {
+				/* Filter out . and .. */
+				continue;
+			}
+			pid = atoi(namelist[i]->d_name);
+			sprintf(path, "%s/%s/proc/kallsyms",
+				symbol_conf.guestmount,
+				namelist[i]->d_name);
+			ret = access(path, R_OK);
+			if (ret) {
+				pr_debug("Can't access file %s\n", path);
+				goto failure;
+			}
+			map_groups__create_kernel_maps(kerninfo_root,
+							pid);
+		}
+failure:
+		free(namelist);
+	}
+
+	return ret;
+}