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Commit 428aff82 authored by Masami Hiramatsu's avatar Masami Hiramatsu Committed by Arnaldo Carvalho de Melo
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perf probe: Ignore vmlinux buildid if offline kernel is given 



Ignore the buildid of running kernel when both of --definition and
--vmlinux is given because that kernel should be off-line.

This also skips post-processing of kprobe event for relocating symbol
and checking blacklist, because it can not be done on off-line kernel.

E.g. without this fix perf shows an error as below
  ----
  $ perf probe --vmlinux=./vmlinux-arm --definition do_sys_open
  ./vmlinux-arm with build id 7a1f76dd56e9c4da707cd3d6333f50748141434b not found, continuing without symbols
  Failed to find symbol do_sys_open in kernel
    Error: Failed to add events.
  ----
with this fix, we can get the definition
  ----
  $ perf probe --vmlinux=./vmlinux-arm --definition do_sys_open
  p:probe/do_sys_open do_sys_open+0
  ----

Signed-off-by: default avatarMasami Hiramatsu <mhiramat@kernel.org>
Cc: Jiri Olsa <jolsa@redhat.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Link: http://lkml.kernel.org/r/147214228193.23638.12581984840822162131.stgit@devbox


Signed-off-by: default avatarArnaldo Carvalho de Melo <acme@redhat.com>
parent 1c20b1d1

tools/perf/Documentation/perf-probe.txt

+2 −0
Original line number Diff line number Diff line
@@ -36,6 +36,8 @@ OPTIONS 
-k::

--vmlinux=PATH::

	Specify vmlinux path which has debuginfo (Dwarf binary).

	Only when using this with --definition, you can give an offline

	vmlinux file.



-m::

--module=MODNAME|PATH::

tools/perf/builtin-probe.c

+9 −1
Original line number Diff line number Diff line
@@ -654,8 +654,16 @@ __cmd_probe(int argc, const char **argv, const char *prefix __maybe_unused) 
			return ret;

		}

		break;

	case 'a':

	case 'D':

		/*

		 * If user gives offline vmlinux, ignore buildid, since

		 * --definition doesn't change running kernel.

		 */

		if (symbol_conf.vmlinux_name)

			symbol_conf.ignore_vmlinux_buildid = true;

		/* fall through */

	case 'a':



		/* Ensure the last given target is used */

		if (params.target && !params.target_used) {

			pr_err("  Error: -x/-m must follow the probe definitions.\n");

tools/perf/util/probe-event.c

+4 −0
Original line number Diff line number Diff line
@@ -674,6 +674,10 @@ post_process_kernel_probe_trace_events(struct probe_trace_event *tevs, 
	char *tmp;

	int i, skipped = 0;



	/* Skip post process if the target is an offline kernel */

	if (symbol_conf.ignore_vmlinux_buildid)

		return 0;



	reloc_sym = kernel_get_ref_reloc_sym();

	if (!reloc_sym) {

		pr_warning("Relocated base symbol is not found!\n");

tools/perf/util/symbol-elf.c

+1 −1
Original line number Diff line number Diff line
@@ -732,7 +732,7 @@ int symsrc__init(struct symsrc *ss, struct dso *dso, const char *name, 
	}



	/* Always reject images with a mismatched build-id: */

	if (dso->has_build_id) {

	if (dso->has_build_id && !symbol_conf.ignore_vmlinux_buildid) {

		u8 build_id[BUILD_ID_SIZE];



		if (elf_read_build_id(elf, build_id, BUILD_ID_SIZE) < 0) {