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Commit 1a8ac29c authored by Masami Hiramatsu's avatar Masami Hiramatsu Committed by Arnaldo Carvalho de Melo
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perf probe: Allow probing on kmodules without dwarf 



Allow probing on kernel modules when 'perf' is built without debuginfo
support.

Currently perf-probe --module requires linking with libdw, but this
doesn't make sense.

E.g.
  ----
  # make NO_DWARF=1
  # ./perf probe -m pcspkr pcspkr_event%return
    Error: unknown switch `m'
  ----

With this patch
  ----
  # ./perf probe -m pcspkr pcspkr_event%return
  Added new event:
    probe:pcspkr_event   (on pcspkr_event%return in pcspkr)

  You can now use it in all perf tools, such as:

          perf record -e probe:pcspkr_event -aR sleep 1
  ----

Signed-off-by: default avatarMasami Hiramatsu <masami.hiramatsu.pt@hitachi.com>
Cc: Jiri Olsa <jolsa@kernel.org>
Cc: Namhyung Kim <namhyung@kernel.org>
Cc: Wang Nan <wangnan0@huawei.com>
Link: http://lkml.kernel.org/r/20151002125832.18617.78721.stgit@localhost.localdomain


Signed-off-by: default avatarArnaldo Carvalho de Melo <acme@redhat.com>
parent fa52ceab

tools/perf/builtin-probe.c

+3 −5
Original line number Diff line number Diff line
@@ -182,10 +182,8 @@ static int opt_set_target(const struct option *opt, const char *str, 
	if  (str) {

		if (!strcmp(opt->long_name, "exec"))

			params.uprobes = true;

#ifdef HAVE_DWARF_SUPPORT

		else if (!strcmp(opt->long_name, "module"))

			params.uprobes = false;

#endif

		else

			return ret;
@@ -490,9 +488,6 @@ __cmd_probe(int argc, const char **argv, const char *prefix __maybe_unused) 
		   "file", "vmlinux pathname"),

	OPT_STRING('s', "source", &symbol_conf.source_prefix,

		   "directory", "path to kernel source"),

	OPT_CALLBACK('m', "module", NULL, "modname|path",

		"target module name (for online) or path (for offline)",

		opt_set_target),

	OPT_BOOLEAN('\0', "no-inlines", &probe_conf.no_inlines,

		"Don't search inlined functions"),

#endif
@@ -509,6 +504,9 @@ __cmd_probe(int argc, const char **argv, const char *prefix __maybe_unused) 
		     opt_set_filter),

	OPT_CALLBACK('x', "exec", NULL, "executable|path",

			"target executable name or path", opt_set_target),

	OPT_CALLBACK('m', "module", NULL, "modname|path",

		"target module name (for online) or path (for offline)",

		opt_set_target),

	OPT_BOOLEAN(0, "demangle", &symbol_conf.demangle,

		    "Enable symbol demangling"),

	OPT_BOOLEAN(0, "demangle-kernel", &symbol_conf.demangle_kernel,

tools/perf/util/probe-event.c

+5 −3
Original line number Diff line number Diff line
@@ -2543,7 +2543,8 @@ static int find_probe_trace_events_from_map(struct perf_probe_event *pev, 
		goto out;

	}



	if (!pev->uprobes && !pp->retprobe) {

	/* Note that the symbols in the kmodule are not relocated */

	if (!pev->uprobes && !pp->retprobe && !pev->target) {

		reloc_sym = kernel_get_ref_reloc_sym();

		if (!reloc_sym) {

			pr_warning("Relocated base symbol is not found!\n");
@@ -2580,8 +2581,9 @@ static int find_probe_trace_events_from_map(struct perf_probe_event *pev, 
		}

		/* Add one probe point */

		tp->address = map->unmap_ip(map, sym->start) + pp->offset;

		/* If we found a wrong one, mark it by NULL symbol */

		if (!pev->uprobes &&



		/* Check the kprobe (not in module) is within .text  */

		if (!pev->uprobes && !pev->target &&

		    kprobe_warn_out_range(sym->name, tp->address)) {

			tp->symbol = NULL;	/* Skip it */

			skipped++;