Commit 14a8fd7c authored by Masami Hiramatsu's avatar Masami Hiramatsu Committed by Steven Rostedt
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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: default avatarMasami 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: default avatarSteven Rostedt <rostedt@goodmis.org>
parent 190b57fc

tools/perf/Documentation/perf-probe.txt

+4 −2
Original line number Diff line number Diff line
@@ -34,9 +34,11 @@ OPTIONS 
	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::

tools/perf/builtin-probe.c

+2 −1
Original line number Diff line number Diff line
@@ -242,7 +242,8 @@ static const struct option options[] = { 
	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,

tools/perf/util/probe-event.c

+43 −9
Original line number Diff line number Diff line
@@ -117,6 +117,10 @@ static struct map *kernel_get_module_map(const char *module) 
	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";
@@ -173,13 +177,20 @@ const char *kernel_get_module_path(const char *module) 
/* 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;



	/* 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 kprobe_convert_to_perf_probe(struct probe_trace_point *tp, 
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 */

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