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: Masami 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: Arnaldo Carvalho de Melo <acme@redhat.com>

diff --git a/tools/perf/Documentation/perf-probe.txt b/tools/perf/Documentation/perf-probe.txt
index 56db4d40d27e5dbc66b952ca02a84991c16ee23f..e6c9902c6d82b0e2535059c1a915356e84856589 100644 (file)
--- a/tools/perf/Documentation/perf-probe.txt
+++ b/tools/perf/Documentation/perf-probe.txt
@@ -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::

diff --git a/tools/perf/builtin-probe.c b/tools/perf/builtin-probe.c
index 7a3d8c47ed2900647b140ab9d790d8aa9a1728b9..b4220cd4acd83a3b2a5ea4fe420d508e86c88515 100644 (file)
--- a/tools/perf/builtin-probe.c
+++ b/tools/perf/builtin-probe.c
@@ -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");

diff --git a/tools/perf/util/probe-event.c b/tools/perf/util/probe-event.c
index 4a49cb8ce7abef79272f23648408a8e71af7aac8..8a1e9e67614f415955c92f89dacec5deec24d800 100644 (file)
--- a/tools/perf/util/probe-event.c
+++ b/tools/perf/util/probe-event.c
@@ -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");

diff --git a/tools/perf/util/symbol-elf.c b/tools/perf/util/symbol-elf.c
index fbe31eff1bebe6cdf097dff8ac112e433065682f..e680371bd5c9b79ca27e47a2f55889606af872ce 100644 (file)
--- a/tools/perf/util/symbol-elf.c
+++ b/tools/perf/util/symbol-elf.c
@@ -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) {