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Commit 0544d422 authored by Adrian Hunter's avatar Adrian Hunter Committed by Arnaldo Carvalho de Melo
Browse files

perf symbols: Add ability to find kcore in build-id cache 



When no vmlinux is found, tools will use kallsyms and, if possible,
kcore.  Add the ability to find kcore in the build-id cache.

Signed-off-by: default avatarAdrian Hunter <adrian.hunter@intel.com>
Cc: David Ahern <dsahern@gmail.com>
Cc: Frederic Weisbecker <fweisbec@gmail.com>
Cc: Jiri Olsa <jolsa@redhat.com>
Cc: Mike Galbraith <efault@gmx.de>
Cc: Namhyung Kim <namhyung@gmail.com>
Cc: Paul Mackerras <paulus@samba.org>
Cc: Peter Zijlstra <a.p.zijlstra@chello.nl>
Cc: Stephane Eranian <eranian@google.com>
Link: http://lkml.kernel.org/r/1381747424-3557-7-git-send-email-adrian.hunter@intel.com


Signed-off-by: default avatarArnaldo Carvalho de Melo <acme@redhat.com>
parent 9a17d726

tools/perf/util/symbol.c

+103 −44
Original line number Diff line number Diff line
@@ -1401,6 +1401,105 @@ int dso__load_vmlinux_path(struct dso *dso, struct map *map, 
	return err;

}



static int find_matching_kcore(struct map *map, char *dir, size_t dir_sz)

{

	char kallsyms_filename[PATH_MAX];

	struct dirent *dent;

	int ret = -1;

	DIR *d;



	d = opendir(dir);

	if (!d)

		return -1;



	while (1) {

		dent = readdir(d);

		if (!dent)

			break;

		if (dent->d_type != DT_DIR)

			continue;

		scnprintf(kallsyms_filename, sizeof(kallsyms_filename),

			  "%s/%s/kallsyms", dir, dent->d_name);

		if (!validate_kcore_modules(kallsyms_filename, map)) {

			strlcpy(dir, kallsyms_filename, dir_sz);

			ret = 0;

			break;

		}

	}



	closedir(d);



	return ret;

}



static char *dso__find_kallsyms(struct dso *dso, struct map *map)

{

	u8 host_build_id[BUILD_ID_SIZE];

	char sbuild_id[BUILD_ID_SIZE * 2 + 1];

	bool is_host = false;

	char path[PATH_MAX];



	if (!dso->has_build_id) {

		/*

		 * Last resort, if we don't have a build-id and couldn't find

		 * any vmlinux file, try the running kernel kallsyms table.

		 */

		goto proc_kallsyms;

	}



	if (sysfs__read_build_id("/sys/kernel/notes", host_build_id,

				 sizeof(host_build_id)) == 0)

		is_host = dso__build_id_equal(dso, host_build_id);



	build_id__sprintf(dso->build_id, sizeof(dso->build_id), sbuild_id);



	/* Use /proc/kallsyms if possible */

	if (is_host) {

		DIR *d;

		int fd;



		/* If no cached kcore go with /proc/kallsyms */

		scnprintf(path, sizeof(path), "%s/[kernel.kcore]/%s",

			  buildid_dir, sbuild_id);

		d = opendir(path);

		if (!d)

			goto proc_kallsyms;

		closedir(d);



		/*

		 * Do not check the build-id cache, until we know we cannot use

		 * /proc/kcore.

		 */

		fd = open("/proc/kcore", O_RDONLY);

		if (fd != -1) {

			close(fd);

			/* If module maps match go with /proc/kallsyms */

			if (!validate_kcore_modules("/proc/kallsyms", map))

				goto proc_kallsyms;

		}



		/* Find kallsyms in build-id cache with kcore */

		if (!find_matching_kcore(map, path, sizeof(path)))

			return strdup(path);



		goto proc_kallsyms;

	}



	scnprintf(path, sizeof(path), "%s/[kernel.kallsyms]/%s",

		  buildid_dir, sbuild_id);



	if (access(path, F_OK)) {

		pr_err("No kallsyms or vmlinux with build-id %s was found\n",

		       sbuild_id);

		return NULL;

	}



	return strdup(path);



proc_kallsyms:

	return strdup("/proc/kallsyms");

}



static int dso__load_kernel_sym(struct dso *dso, struct map *map,

				symbol_filter_t filter)

{
@@ -1449,52 +1548,12 @@ static int dso__load_kernel_sym(struct dso *dso, struct map *map, 
	if (symbol_conf.symfs[0] != 0)

		return -1;



	/*

	 * Say the kernel DSO was created when processing the build-id header table,

	 * we have a build-id, so check if it is the same as the running kernel,

	 * using it if it is.

	 */

	if (dso->has_build_id) {

		u8 kallsyms_build_id[BUILD_ID_SIZE];

		char sbuild_id[BUILD_ID_SIZE * 2 + 1];



		if (sysfs__read_build_id("/sys/kernel/notes", kallsyms_build_id,

					 sizeof(kallsyms_build_id)) == 0) {

			if (dso__build_id_equal(dso, kallsyms_build_id)) {

				kallsyms_filename = "/proc/kallsyms";

				goto do_kallsyms;

			}

		}

		/*

		 * Now look if we have it on the build-id cache in

		 * $HOME/.debug/[kernel.kallsyms].

		 */

		build_id__sprintf(dso->build_id, sizeof(dso->build_id),

				  sbuild_id);



		if (asprintf(&kallsyms_allocated_filename,

			     "%s/.debug/[kernel.kallsyms]/%s",

			     getenv("HOME"), sbuild_id) == -1) {

			pr_err("Not enough memory for kallsyms file lookup\n");

	kallsyms_allocated_filename = dso__find_kallsyms(dso, map);

	if (!kallsyms_allocated_filename)

		return -1;

		}



	kallsyms_filename = kallsyms_allocated_filename;



		if (access(kallsyms_filename, F_OK)) {

			pr_err("No kallsyms or vmlinux with build-id %s "

			       "was found\n", sbuild_id);

			free(kallsyms_allocated_filename);

			return -1;

		}

	} else {

		/*

		 * Last resort, if we don't have a build-id and couldn't find

		 * any vmlinux file, try the running kernel kallsyms table.

		 */

		kallsyms_filename = "/proc/kallsyms";

	}



do_kallsyms:

	err = dso__load_kallsyms(dso, kallsyms_filename, map, filter);

	if (err > 0)