perf probe: Support adding probes on offline kernel modules

Support adding probes on offline kernel modules. This enables perf-probe to trace kernel-module init functions via perf-probe. If user gives the path of module with -m option, perf-probe expects the module is offline. This feature works with --add, --funcs, and --vars. E.g) # perf probe -m /lib/modules/`uname -r`/kernel/fs/btrfs/btrfs.ko \ -a "extent_io_init:5 extent_state_cache" Add new events: probe:extent_io_init (on extent_io_init:5 with extent_state_cache) probe:extent_io_init_1 (on extent_io_init:5 with extent_state_cache) You can now use it on all perf tools, such as: perf record -e probe:extent_io_init_1 -aR sleep 1 Signed-off-by: Masami Hiramatsu <masami.hiramatsu.pt@hitachi.com> Cc: Peter Zijlstra <a.p.zijlstra@chello.nl> Cc: Frederic Weisbecker <fweisbec@gmail.com> Cc: Paul Mackerras <paulus@samba.org> Cc: Ingo Molnar <mingo@elte.hu> Cc: Arnaldo Carvalho de Melo <acme@ghostprotocols.net> Link: http://lkml.kernel.org/r/20110627072751.6528.10230.stgit@fedora15 Signed-off-by: Steven Rostedt <rostedt@goodmis.org>

perf probe: Support adding probes on offline kernel modules
Support adding probes on offline kernel modules. This enables perf-probe to trace kernel-module init functions via perf-probe. If user gives the path of module with -m option, perf-probe expects the module is offline. This feature works with --add, --funcs, and --vars. E.g) # perf probe -m /lib/modules/`uname -r`/kernel/fs/btrfs/btrfs.ko \ -a "extent_io_init:5 extent_state_cache" Add new events: probe:extent_io_init (on extent_io_init:5 with extent_state_cache) probe:extent_io_init_1 (on extent_io_init:5 with extent_state_cache) You can now use it on all perf tools, such as: perf record -e probe:extent_io_init_1 -aR sleep 1 Signed-off-by: Masami Hiramatsu <masami.hiramatsu.pt@hitachi.com> Cc: Peter Zijlstra <a.p.zijlstra@chello.nl> Cc: Frederic Weisbecker <fweisbec@gmail.com> Cc: Paul Mackerras <paulus@samba.org> Cc: Ingo Molnar <mingo@elte.hu> Cc: Arnaldo Carvalho de Melo <acme@ghostprotocols.net> Link: http://lkml.kernel.org/r/20110627072751.6528.10230.stgit@fedora15 Signed-off-by: Steven Rostedt <rostedt@goodmis.org>
Masami Hiramatsu · Steven Rostedt
1 parent 190b57fcb9
Showing 3 changed files with 49 additions and 12 deletions Side-by-side Diff
tools/perf/Documentation/perf-probe.txt
tools/perf/builtin-probe.c
tools/perf/util/probe-event.c
@@ -34,9 +34,11 @@
 	Specify vmlinux path which has debuginfo (Dwarf binary).
  
 -m::
---module=MODNAME::
+--module=MODNAME|PATH::
 	Specify module name in which perf-probe searches probe points
-	or lines.
+	or lines. If a path of module file is passed, perf-probe
+	treat it as an offline module (this means you can add a probe on
+        a module which has not been loaded yet).
  
 -s::
 --source=PATH::
@@ -242,7 +242,8 @@
 	OPT_STRING('s', "source", &symbol_conf.source_prefix,
 		   "directory", "path to kernel source"),
 	OPT_STRING('m', "module", &params.target_module,
-		   "modname", "target module name"),
+		   "modname|path",
+		   "target module name (for online) or path (for offline)"),
 #endif
 	OPT__DRY_RUN(&probe_event_dry_run),
 	OPT_INTEGER('\0', "max-probes", &params.max_probe_points,
@@ -117,6 +117,10 @@
 	struct rb_node *nd;
 	struct map_groups *grp = &machine.kmaps;
  
+	/* A file path -- this is an offline module */
+	if (module && strchr(module, '/'))
+		return machine__new_module(&machine, 0, module);
+
 	if (!module)
 		module = "kernel";
  
  
@@ -173,12 +177,19 @@
 /* Open new debuginfo of given module */
 static struct debuginfo *open_debuginfo(const char *module)
 {
-	const char *path = kernel_get_module_path(module);
+	const char *path;
  
-	if (!path) {
-		pr_err("Failed to find path of %s module.\n",
-		       module ?: "kernel");
-		return NULL;
+	/* A file path -- this is an offline module */
+	if (module && strchr(module, '/'))
+		path = module;
+	else {
+		path = kernel_get_module_path(module);
+
+		if (!path) {
+			pr_err("Failed to find path of %s module.\n",
+			       module ?: "kernel");
+			return NULL;
+		}
 	}
 	return debuginfo__new(path);
 }
  
  
@@ -229,13 +240,36 @@
 static int add_module_to_probe_trace_events(struct probe_trace_event *tevs,
 					    int ntevs, const char *module)
 {
-	int i;
+	int i, ret = 0;
+	char *tmp;
+
+	if (!module)
+		return 0;
+
+	tmp = strrchr(module, '/');
+	if (tmp) {
+		/* This is a module path -- get the module name */
+		module = strdup(tmp + 1);
+		if (!module)
+			return -ENOMEM;
+		tmp = strchr(module, '.');
+		if (tmp)
+			*tmp = '\0';
+		tmp = (char *)module;	/* For free() */
+	}
+
 	for (i = 0; i < ntevs; i++) {
 		tevs[i].point.module = strdup(module);
-		if (!tevs[i].point.module)
-			return -ENOMEM;
+		if (!tevs[i].point.module) {
+			ret = -ENOMEM;
+			break;
+		}
 	}
-	return 0;
+
+	if (tmp)
+		free(tmp);
+
+	return ret;
 }
  
 /* Try to find perf_probe_event with debuginfo */
...	...	@@ -34,9 +34,11 @@
34	34	Specify vmlinux path which has debuginfo (Dwarf binary).
35	35
36	36	-m::
37		---module=MODNAME::
	37	+--module=MODNAME\|PATH::
38	38	Specify module name in which perf-probe searches probe points
39		- or lines.
	39	+ or lines. If a path of module file is passed, perf-probe
	40	+ treat it as an offline module (this means you can add a probe on
	41	+ a module which has not been loaded yet).
40	42
41	43	-s::
42	44	--source=PATH::
...	...	@@ -242,7 +242,8 @@
242	242	OPT_STRING('s', "source", &symbol_conf.source_prefix,
243	243	"directory", "path to kernel source"),
244	244	OPT_STRING('m', "module", &params.target_module,
245		- "modname", "target module name"),
	245	+ "modname\|path",
	246	+ "target module name (for online) or path (for offline)"),
246	247	#endif
247	248	OPT__DRY_RUN(&probe_event_dry_run),
248	249	OPT_INTEGER('\0', "max-probes", &params.max_probe_points,
...	...	@@ -117,6 +117,10 @@
117	117	struct rb_node *nd;
118	118	struct map_groups *grp = &machine.kmaps;
119	119
	120	+ /* A file path -- this is an offline module */
	121	+ if (module && strchr(module, '/'))
	122	+ return machine__new_module(&machine, 0, module);
	123	+
120	124	if (!module)
121	125	module = "kernel";
122	126
123	127
...	...	@@ -173,12 +177,19 @@
173	177	/* Open new debuginfo of given module */
174	178	static struct debuginfo open_debuginfo(const char module)
175	179	{
176		- const char *path = kernel_get_module_path(module);
	180	+ const char *path;
177	181
178		- if (!path) {
179		- pr_err("Failed to find path of %s module.\n",
180		- module ?: "kernel");
181		- return NULL;
	182	+ /* A file path -- this is an offline module */
	183	+ if (module && strchr(module, '/'))
	184	+ path = module;
	185	+ else {
	186	+ path = kernel_get_module_path(module);
	187	+
	188	+ if (!path) {
	189	+ pr_err("Failed to find path of %s module.\n",
	190	+ module ?: "kernel");
	191	+ return NULL;
	192	+ }
182	193	}
183	194	return debuginfo__new(path);
184	195	}
185	196
186	197
...	...	@@ -229,13 +240,36 @@
229	240	static int add_module_to_probe_trace_events(struct probe_trace_event *tevs,
230	241	int ntevs, const char *module)
231	242	{
232		- int i;
	243	+ int i, ret = 0;
	244	+ char *tmp;
	245	+
	246	+ if (!module)
	247	+ return 0;
	248	+
	249	+ tmp = strrchr(module, '/');
	250	+ if (tmp) {
	251	+ /* This is a module path -- get the module name */
	252	+ module = strdup(tmp + 1);
	253	+ if (!module)
	254	+ return -ENOMEM;
	255	+ tmp = strchr(module, '.');
	256	+ if (tmp)
	257	+ *tmp = '\0';
	258	+ tmp = (char )module; / For free() */
	259	+ }
	260	+
233	261	for (i = 0; i < ntevs; i++) {
234	262	tevs[i].point.module = strdup(module);
235		- if (!tevs[i].point.module)
236		- return -ENOMEM;
	263	+ if (!tevs[i].point.module) {
	264	+ ret = -ENOMEM;
	265	+ break;
	266	+ }
237	267	}
238		- return 0;
	268	+
	269	+ if (tmp)
	270	+ free(tmp);
	271	+
	272	+ return ret;
239	273	}
240	274
241	275	/* Try to find perf_probe_event with debuginfo */