perf tools: Add symfs option for off-box analysis using specified tree

The symfs argument allows analysis of perf.data file using a locally accessible filesystem tree with debug symbols - e.g., tree created during image builds, sshfs mount, loop mounted KVM disk images, USB keys, initrds, etc. Anything with an OS tree can be analyzed from anywhere without the need to populate a local data store with build-ids.

Signed-off-by David Ahern <[email protected]>

---
 tools/perf/builtin-annotate.c  |   16 +++++--
 tools/perf/builtin-diff.c      |    2 +
 tools/perf/builtin-report.c    |    2 +
 tools/perf/builtin-timechart.c |    2 +
 tools/perf/util/hist.c         |   14 +++++-
 tools/perf/util/symbol.c       |   82 +++++++++++++++++++++++++---------------
 tools/perf/util/symbol.h       |    1 +
 7 files changed, 80 insertions(+), 39 deletions(-)

tools/perf/builtin-annotate.c +2 -2

index 569a276..0c47bee 100644
@@ -280,7 +280,8 @@ static int hist_entry__tty_annotate(struct hist_entry *he)
 	struct map *map = he->ms.map;
 	struct dso *dso = map->dso;
 	struct symbol *sym = he->ms.sym;
-	const char *filename = dso->long_name, *d_filename;
+	const char *filename = dso->long_name;
+	char d_filename[PATH_MAX];
 	u64 len;
 	LIST_HEAD(head);
 	struct objdump_line *pos, *n;

@@ -288,10 +289,13 @@ static int hist_entry__tty_annotate(struct hist_entry *he)
 	if (hist_entry__annotate(he, &head, 0) < 0)
 		return -1;
 
-	if (full_paths)

tools/perf/builtin-annotate.c +2 -0

 	len = sym->end - sym->start;
 

@@ -437,6 +441,8 @@ static const struct option options[] = {
 		    "print matching source lines (may be slow)"),
 	OPT_BOOLEAN('P', "full-paths", &full_paths,
 		    "Don't shorten the displayed pathnames"),
+	OPT_STRING(0, "symfs", &symbol_conf.symfs, "directory",
+		    "Look for files with symbols relative to this directory"),
 	OPT_END()
 };
 

tools/perf/builtin-diff.c +2 -0

index 5e1a043..71126a6 100644
@@ -192,6 +192,8 @@ static const struct option options[] = {
 	OPT_STRING('t', "field-separator", &symbol_conf.field_sep, "separator",
 		   "separator for columns, no spaces will be added between "
 		   "columns '.' is reserved."),
+	OPT_STRING(0, "symfs", &symbol_conf.symfs, "directory",
+		    "Look for files with symbols relative to this directory"),
 	OPT_END()
 };
 

tools/perf/builtin-report.c +2 -0

index 904519f..57b0f49 100644
@@ -479,6 +479,8 @@ static const struct option options[] = {
 		   "columns '.' is reserved."),
 	OPT_BOOLEAN('U', "hide-unresolved", &hide_unresolved,
 		    "Only display entries resolved to a symbol"),
+	OPT_STRING(0, "symfs", &symbol_conf.symfs, "directory",
+		    "Look for files with symbols relative to this directory"),
 	OPT_END()
 };
 

tools/perf/builtin-timechart.c +2 -0

index d2fc461..965aa4e 100644
@@ -1021,6 +1021,8 @@ static const struct option options[] = {
 	OPT_CALLBACK('p', "process", NULL, "process",
 		      "process selector. Pass a pid or process name.",
 		       parse_process),
+	OPT_STRING(0, "symfs", &symbol_conf.symfs, "directory",
+		    "Look for files with symbols relative to this directory"),
 	OPT_END()
 };
 

tools/perf/util/hist.c +0 -0

index 2022e87..b24ae53 100644

tools/perf/util/hist.c +3 -2

+	}
 
 	if (filename == NULL) {
 		if (dso->has_build_id) {

@@ -1100,9 +1106,9 @@ int hist_entry__annotate(struct hist_entry *self, struct list_head *head,
 			return -ENOMEM;
 		}
 		goto fallback;
-	} else if (readlink(filename, command, sizeof(command)) < 0 ||
+	} else if (readlink(symfs_filename, command, sizeof(command)) < 0 ||
 		   strstr(command, "[kernel.kallsyms]") ||
-		   access(filename, R_OK)) {
+		   access(symfs_filename, R_OK)) {
 		free(filename);
 fallback:
 		/*

tools/perf/util/hist.c +1 -1

 		free_filename = false;
 	}
 

@@ -1137,7 +1145,7 @@ fallback:
 		 "objdump --start-address=0x%016Lx --stop-address=0x%016Lx -dS -C %s|grep -v %s|expand",
 		 map__rip_2objdump(map, sym->start),
 		 map__rip_2objdump(map, sym->end),
-		 filename, filename);
+		 symfs_filename, filename);
 
 	pr_debug("Executing: %s\n", command);
 

tools/perf/util/symbol.c +5 -1

index a348906..7a0d284 100644
@@ -41,6 +41,7 @@ struct symbol_conf symbol_conf = {
 	.exclude_other	  = true,
 	.use_modules	  = true,
 	.try_vmlinux_path = true,
+	.symfs           = "",
 };
 
 int dso__name_len(const struct dso *self)

@@ -833,8 +834,11 @@ static int dso__synthesize_plt_symbols(struct  dso *self, struct map *map,
 	char sympltname[1024];
 	Elf *elf;
 	int nr = 0, symidx, fd, err = 0;
+	char name[PATH_MAX];
 
-	fd = open(self->long_name, O_RDONLY);
+	snprintf(name, sizeof(name), "%s%s",
+		 symbol_conf.symfs, self->long_name);
+	fd = open(name, O_RDONLY);
 	if (fd < 0)
 		goto out;
 

tools/perf/util/symbol.c +10 -7

+			    (dso__build_id_filename(self, name, size) == NULL)) {
 				continue;
+			}
 			break;
 		case DSO__ORIG_FEDORA:
-			snprintf(name, size, "/usr/lib/debug%s.debug",
-				 self->long_name);
+			snprintf(name, size, "%s/usr/lib/debug%s.debug",
+				 symbol_conf.symfs, self->long_name);
 			break;
 		case DSO__ORIG_UBUNTU:
-			snprintf(name, size, "/usr/lib/debug%s",
-				 self->long_name);
+			snprintf(name, size, "%s/usr/lib/debug%s",
+				 symbol_conf.symfs, self->long_name);
 			break;
 		case DSO__ORIG_BUILDID: {
 			char build_id_hex[BUILD_ID_SIZE * 2 + 1];

@@ -1467,12 +1474,13 @@ int dso__load(struct dso *self, struct map *map, symbol_filter_t filter)
 					  sizeof(self->build_id),
 					  build_id_hex);
 			snprintf(name, size,
-				 "/usr/lib/debug/.build-id/%.2s/%s.debug",
-				 build_id_hex, build_id_hex + 2);
+				 "%s/usr/lib/debug/.build-id/%.2s/%s.debug",
+				 symbol_conf.symfs, build_id_hex, build_id_hex + 2);
 			}
 			break;
 		case DSO__ORIG_DSO:
-			snprintf(name, size, "%s", self->long_name);
+			snprintf(name, size, "%s%s",
+			     symbol_conf.symfs, self->long_name);
 			break;
 		case DSO__ORIG_GUEST_KMODULE:
 			if (map->groups && map->groups->machine)

tools/perf/util/symbol.c +7 -14

+	fd = open(symfs_vmlinux, O_RDONLY);
 	if (fd < 0)
 		return -1;
 
 	dso__set_loaded(self, map->type);
-	err = dso__load_sym(self, map, vmlinux, fd, filter, 0, 0);
+	err = dso__load_sym(self, map, symfs_vmlinux, fd, filter, 0, 0);
 	close(fd);
 
 	if (err > 0)
-		pr_debug("Using %s for symbols\n", vmlinux);
+		pr_debug("Using %s for symbols\n", symfs_vmlinux);
 
 	return err;
 }

@@ -1861,6 +1872,10 @@ static int dso__load_kernel_sym(struct dso *self, struct map *map,
 			goto out_fixup;
 	}
 
+	/* do not try local files if a symfs was given */
+	if (strlen(symbol_conf.symfs) != 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,

@@ -2210,9 +2225,6 @@ static int vmlinux_path__init(void)
 	struct utsname uts;
 	char bf[PATH_MAX];
 
-	if (uname(&uts) < 0)
-		return -1;
-
 	vmlinux_path = malloc(sizeof(char *) * 5);
 	if (vmlinux_path == NULL)
 		return -1;

@@ -2225,22 +2237,30 @@ static int vmlinux_path__init(void)
 	if (vmlinux_path[vmlinux_path__nr_entries] == NULL)
 		goto out_fail;
 	++vmlinux_path__nr_entries;
-	snprintf(bf, sizeof(bf), "/boot/vmlinux-%s", uts.release);
-	vmlinux_path[vmlinux_path__nr_entries] = strdup(bf);
-	if (vmlinux_path[vmlinux_path__nr_entries] == NULL)
-		goto out_fail;
-	++vmlinux_path__nr_entries;
-	snprintf(bf, sizeof(bf), "/lib/modules/%s/build/vmlinux", uts.release);
-	vmlinux_path[vmlinux_path__nr_entries] = strdup(bf);
-	if (vmlinux_path[vmlinux_path__nr_entries] == NULL)
-		goto out_fail;

tools/perf/util/symbol.c +21 -0

+		if (uname(&uts) < 0)
+			return -1;
+
+		snprintf(bf, sizeof(bf), "/boot/vmlinux-%s", uts.release);
+		vmlinux_path[vmlinux_path__nr_entries] = strdup(bf);
+		if (vmlinux_path[vmlinux_path__nr_entries] == NULL)
+			goto out_fail;
+		++vmlinux_path__nr_entries;
+		snprintf(bf, sizeof(bf), "/lib/modules/%s/build/vmlinux",
+			 uts.release);
+		vmlinux_path[vmlinux_path__nr_entries] = strdup(bf);
+		if (vmlinux_path[vmlinux_path__nr_entries] == NULL)
+			goto out_fail;
+		++vmlinux_path__nr_entries;
+		snprintf(bf, sizeof(bf), "/usr/lib/debug/lib/modules/%s/vmlinux",
+			 uts.release);
+		vmlinux_path[vmlinux_path__nr_entries] = strdup(bf);
+		if (vmlinux_path[vmlinux_path__nr_entries] == NULL)
+			goto out_fail;
+		++vmlinux_path__nr_entries;
+	}
 
 	return 0;
 

tools/perf/util/symbol.h +1 -0

index 038f220..bbe90d1 100644
@@ -85,6 +85,7 @@ struct symbol_conf {
        struct strlist	*dso_list,
 			*comm_list,
 			*sym_list;
+	const char	*symfs;
 };
 
 extern struct symbol_conf symbol_conf;

Signature · 6 lines

1.7.2.3

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Em Tue, Dec 07, 2010 at 07:42:54PM -0700, David Ahern escreveu:

Quoted 36 lines

The symfs argument allows analysis of perf.data file using a locally accessible filesystem tree with debug symbols - e.g., tree created during image builds, sshfs mount, loop mounted KVM disk images, USB keys, initrds, etc. Anything with an OS tree can be analyzed from anywhere without the need to populate a local data store with build-ids.

Signed-off-by David Ahern <[email protected]>

---
 tools/perf/builtin-annotate.c  |   16 +++++--
 tools/perf/builtin-diff.c      |    2 +
 tools/perf/builtin-report.c    |    2 +
 tools/perf/builtin-timechart.c |    2 +
 tools/perf/util/hist.c         |   14 +++++-
 tools/perf/util/symbol.c       |   82 +++++++++++++++++++++++++---------------
 tools/perf/util/symbol.h       |    1 +
 7 files changed, 80 insertions(+), 39 deletions(-)

tools/perf/builtin-annotate.c +2 -1

index 569a276..0c47bee 100644
@@ -280,7 +280,8 @@ static int hist_entry__tty_annotate(struct hist_entry *he)
 	struct map *map = he->ms.map;
 	struct dso *dso = map->dso;
 	struct symbol *sym = he->ms.sym;
-	const char *filename = dso->long_name, *d_filename;
+	const char *filename = dso->long_name;
+	char d_filename[PATH_MAX];
 	u64 len;
 	LIST_HEAD(head);
 	struct objdump_line *pos, *n;

@@ -288,10 +289,13 @@ static int hist_entry__tty_annotate(struct hist_entry *he)
 	if (hist_entry__annotate(he, &head, 0) < 0)
 		return -1;
 

tools/perf/builtin-annotate.c static int hist_entry__tty_annotate(struct hist_entry *he) · line 298

Quoted 11 lines

tools/perf/builtin-annotate.c +7 -4

-	if (full_paths)
-		d_filename = filename;
-	else
-		d_filename = basename(filename);
+	if (full_paths) {
+		snprintf(d_filename, sizeof(d_filename), "%s%s",
+			 symbol_conf.symfs, filename);
+	} else {
+		snprintf(d_filename, sizeof(d_filename), "%s/%s",
+			 symbol_conf.symfs, basename(filename));
+	}

Are you sure about the one above? I guess you don't need to concat here, its just informative message, if you're using --symfs, you know everything is from there, and in the !full_paths case the resulting filename will be bogus, right?

tools/perf/builtin-annotate.c static const struct option options[] = { · line 447

Quoted 11 lines

tools/perf/builtin-annotate.c +2 -0

 	len = sym->end - sym->start;
 

@@ -437,6 +441,8 @@ static const struct option options[] = {
 		    "print matching source lines (may be slow)"),
 	OPT_BOOLEAN('P', "full-paths", &full_paths,
 		    "Don't shorten the displayed pathnames"),
+	OPT_STRING(0, "symfs", &symbol_conf.symfs, "directory",
+		    "Look for files with symbols relative to this directory"),
 	OPT_END()
 };

Quoted 7 lines

tools/perf/util/hist.c +0 -0

index 2022e87..b24ae53 100644
@@ -1092,6 +1092,12 @@ int hist_entry__annotate(struct hist_entry *self, struct list_head *head,
 	FILE *file;
 	int err = 0;

tools/perf/util/hist.c int hist_entry__annotate(struct hist_entry *self, struct list_head *head, · line 1099

Quoted 6 lines

tools/perf/util/hist.c +5 -0

 	u64 len;
+	char symfs_filename[PATH_MAX];
+
+	if (filename) {
+		snprintf(symfs_filename, sizeof(symfs_filename), "%s%s",
+		 symbol_conf.symfs, filename);

Above you have tab/space damage

Quoted 17 lines

tools/perf/util/hist.c +3 -2

+	}
 
 	if (filename == NULL) {
 		if (dso->has_build_id) {

@@ -1100,9 +1106,9 @@ int hist_entry__annotate(struct hist_entry *self, struct list_head *head,
 			return -ENOMEM;
 		}
 		goto fallback;
-	} else if (readlink(filename, command, sizeof(command)) < 0 ||
+	} else if (readlink(symfs_filename, command, sizeof(command)) < 0 ||
 		   strstr(command, "[kernel.kallsyms]") ||
-		   access(filename, R_OK)) {
+		   access(symfs_filename, R_OK)) {
 		free(filename);
 fallback:
 		/*

tools/perf/util/hist.c fallback: · line 1121

Quoted 6 lines

tools/perf/util/hist.c +2 -0

@@ -1111,6 +1117,8 @@ fallback:
 		 * DSO is the same as when 'perf record' ran.
 		 */
 		filename = dso->long_name;
+		snprintf(symfs_filename, sizeof(symfs_filename), "%s%s",
+		 symbol_conf.symfs, filename);

Ditto above

Quoted 39 lines

tools/perf/util/hist.c +1 -1

 		free_filename = false;
 	}
 

@@ -1137,7 +1145,7 @@ fallback:
 		 "objdump --start-address=0x%016Lx --stop-address=0x%016Lx -dS -C %s|grep -v %s|expand",
 		 map__rip_2objdump(map, sym->start),
 		 map__rip_2objdump(map, sym->end),
-		 filename, filename);
+		 symfs_filename, filename);
 
 	pr_debug("Executing: %s\n", command);
 

tools/perf/util/symbol.c +5 -1

index a348906..7a0d284 100644
@@ -41,6 +41,7 @@ struct symbol_conf symbol_conf = {
 	.exclude_other	  = true,
 	.use_modules	  = true,
 	.try_vmlinux_path = true,
+	.symfs           = "",
 };
 
 int dso__name_len(const struct dso *self)

@@ -833,8 +834,11 @@ static int dso__synthesize_plt_symbols(struct  dso *self, struct map *map,
 	char sympltname[1024];
 	Elf *elf;
 	int nr = 0, symidx, fd, err = 0;
+	char name[PATH_MAX];
 
-	fd = open(self->long_name, O_RDONLY);
+	snprintf(name, sizeof(name), "%s%s",
+		 symbol_conf.symfs, self->long_name);
+	fd = open(name, O_RDONLY);
 	if (fd < 0)
 		goto out;
 

tools/perf/util/symbol.c int dso__load(struct dso *self, struct map *map, symbol_filter_t filter) · line 1454

Quoted 6 lines

tools/perf/util/symbol.c +2 -1

@@ -1446,16 +1450,19 @@ int dso__load(struct dso *self, struct map *map, symbol_filter_t filter)
 	     self->origin++) {
 		switch (self->origin) {
 		case DSO__ORIG_BUILD_ID_CACHE:
-			if (dso__build_id_filename(self, name, size) == NULL)
+			/* skip the locally configured cache if a symfs is given */
+			if ((strlen(symbol_conf.symfs) != 0) ||

I suggest you use:

			if (symbol_conf.symfs[1] ||

cheaper :)

tools/perf/util/symbol.c static int dso__load_vmlinux(struct dso *self, struct map *map, · line 1791

Quoted 8 lines

tools/perf/util/symbol.c +3 -1

@@ -1778,17 +1786,20 @@ static int dso__load_vmlinux(struct dso *self, struct map *map,
 			     const char *vmlinux, symbol_filter_t filter)
 {
 	int err = -1, fd;
+	char symfs_vmlinux[PATH_MAX];
-	fd = open(vmlinux, O_RDONLY);
+	snprintf(symfs_vmlinux, sizeof(symfs_vmlinux), "%s/%s",
+		 symbol_conf.symfs, vmlinux);

Its userspace, so stack is plenty, but I guess if using asprintf wouldn't be better...

I.e. if we were programming some kernel module, creating a 4K stack variable would be considered bad practice, so I think it is here as well.

Quoted 20 lines

tools/perf/util/symbol.c +3 -2

+	fd = open(symfs_vmlinux, O_RDONLY);
 	if (fd < 0)
 		return -1;
 
 	dso__set_loaded(self, map->type);
-	err = dso__load_sym(self, map, vmlinux, fd, filter, 0, 0);
+	err = dso__load_sym(self, map, symfs_vmlinux, fd, filter, 0, 0);
 	close(fd);
 
 	if (err > 0)
-		pr_debug("Using %s for symbols\n", vmlinux);
+		pr_debug("Using %s for symbols\n", symfs_vmlinux);
 
 	return err;
 }

@@ -1861,6 +1872,10 @@ static int dso__load_kernel_sym(struct dso *self, struct map *map,
 			goto out_fixup;
 	}
 

tools/perf/util/symbol.c static int dso__load_kernel_sym(struct dso *self, struct map *map, · line 1878

Quoted 4 lines

tools/perf/util/symbol.c +4 -0

+	/* do not try local files if a symfs was given */
+	if (strlen(symbol_conf.symfs) != 0)
+		return -1;
+

Quoted 26 lines

tools/perf/util/symbol.c +0 -12

 	/*
 	 * 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,

@@ -2210,9 +2225,6 @@ static int vmlinux_path__init(void)
 	struct utsname uts;
 	char bf[PATH_MAX];
 
-	if (uname(&uts) < 0)
-		return -1;
-
 	vmlinux_path = malloc(sizeof(char *) * 5);
 	if (vmlinux_path == NULL)
 		return -1;

@@ -2225,22 +2237,30 @@ static int vmlinux_path__init(void)
 	if (vmlinux_path[vmlinux_path__nr_entries] == NULL)
 		goto out_fail;
 	++vmlinux_path__nr_entries;
-	snprintf(bf, sizeof(bf), "/boot/vmlinux-%s", uts.release);
-	vmlinux_path[vmlinux_path__nr_entries] = strdup(bf);
-	if (vmlinux_path[vmlinux_path__nr_entries] == NULL)
-		goto out_fail;
-	++vmlinux_path__nr_entries;
-	snprintf(bf, sizeof(bf), "/lib/modules/%s/build/vmlinux", uts.release);
-	vmlinux_path[vmlinux_path__nr_entries] = strdup(bf);
-	if (vmlinux_path[vmlinux_path__nr_entries] == NULL)
-		goto out_fail;

tools/perf/util/symbol.c static int vmlinux_path__init(void) · line 2242

Quoted 10 lines

tools/perf/util/symbol.c +3 -7

-	++vmlinux_path__nr_entries;
-	snprintf(bf, sizeof(bf), "/usr/lib/debug/lib/modules/%s/vmlinux",
-		 uts.release);
-	vmlinux_path[vmlinux_path__nr_entries] = strdup(bf);
-	if (vmlinux_path[vmlinux_path__nr_entries] == NULL)
-		goto out_fail;
-	++vmlinux_path__nr_entries;
+
+	/* if no symfs has been given try running kernel version too */
+	if (strlen(symbol_conf.symfs) == 0) {

Do it as:

	if (!symbol_conf.symfs[1])
		return 0;

And then the patch can be made smaller.

Quoted 5 lines

Em Tue, Dec 07, 2010 at 07:42:54PM -0700, David Ahern escreveu:

tools/perf/util/symbol.c int dso__load(struct dso *self, struct map *map, symbol_filter_t filter) · line 1454

Quoted 1 line

tools/perf/util/symbol.c +1 -0

+			if ((strlen(symbol_conf.symfs) != 0) ||

I suggest you use:

Quoted 3 lines

			if (symbol_conf.symfs[1] ||

cheaper :)

Changed. I presume you meant: symbol_conf.symfs[0] -- ie., element 0 has something other than '\0' which means strlen > 0

Quoted 12 lines

tools/perf/util/symbol.c static int dso__load_vmlinux(struct dso *self, struct map *map, · line 1791

Quoted 8 lines

tools/perf/util/symbol.c +3 -1

@@ -1778,17 +1786,20 @@ static int dso__load_vmlinux(struct dso *self, struct map *map,
 			     const char *vmlinux, symbol_filter_t filter)
 {
 	int err = -1, fd;
+	char symfs_vmlinux[PATH_MAX];
-	fd = open(vmlinux, O_RDONLY);
+	snprintf(symfs_vmlinux, sizeof(symfs_vmlinux), "%s/%s",
+		 symbol_conf.symfs, vmlinux);

Its userspace, so stack is plenty, but I guess if using asprintf wouldn't be better...

Quoted 3 lines

I.e. if we were programming some kernel module, creating a 4K stack variable would be considered bad practice, so I think it is here as well.

Declaring symfs_vmlinux on the stack is consistent with other PATH_MAX declarations within perf, and especially within util/symbol.c.

Quoted 7 lines

tools/perf/util/symbol.c static int vmlinux_path__init(void) · line 2242

Quoted 1 line

tools/perf/util/symbol.c +1 -0

+	if (strlen(symbol_conf.symfs) == 0) {

Do it as:

	if (!symbol_conf.symfs[1])
		return 0;

Quoted 1 line

And then the patch can be made smaller.

Done.

I also added the symfs option to the Documentation files. Will send an updated patch.