[PATCH -tip perf/probes 3/5] perf/probes: Fall back to non-dwarf if possible

Masami Hiramatsu
2009-11-04T00:18:10Z

Fall back to non-dwarf probe point if the probe definition may not
need dwarf analysis, when perf can't find vmlinux/debuginfo.
This might skip some inlined code of target function.

Signed-off-by: Masami Hiramatsu <mhiramat@redhat.com>
Cc: Ingo Molnar <mingo@elte.hu>
Cc: Steven Rostedt <rostedt@goodmis.org>
Cc: Jim Keniston <jkenisto@us.ibm.com>
Cc: Ananth N Mavinakayanahalli <ananth@in.ibm.com>
Cc: Christoph Hellwig <hch@infradead.org>
Cc: Frank Ch. Eigler <fche@redhat.com>
Cc: Frederic Weisbecker <fweisbec@gmail.com>
Cc: Jason Baron <jbaron@redhat.com>
Cc: K.Prasad <prasad@linux.vnet.ibm.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Srikar Dronamraju <srikar@linux.vnet.ibm.com>
---

tools/perf/builtin-probe.c | 65 +++++++++++++++++++++++-----------------
tools/perf/util/probe-finder.c | 8 +++--
2 files changed, 42 insertions(+), 31 deletions(-)

diff --git a/tools/perf/builtin-probe.c b/tools/perf/builtin-probe.c
index 454ddfc..e44491b 100644
--- a/tools/perf/builtin-probe.c
+++ b/tools/perf/builtin-probe.c
@@ -189,7 +189,7 @@ static void parse_probe_event(const char *str)
/* Parse probe point */
parse_probe_point(argv[0], pp);
free(argv[0]);
- if (pp->file)
+ if (pp->file || pp->line)
session.need_dwarf = 1;

/* Copy arguments */
@@ -347,36 +347,24 @@ int cmd_probe(int argc, const char **argv, const char *prefix __used)
if (session.nr_probe == 0)
usage_with_options(probe_usage, options);

-#ifdef NO_LIBDWARF
if (session.need_dwarf)
- semantic_error("Dwarf-analysis is not supported");
-#endif
-
- /* Synthesize probes without dwarf */
- for (j = 0; j < session.nr_probe; j++) {
-#ifndef NO_LIBDWARF
- if (!session.probes[j].retprobe) {
- session.need_dwarf = 1;
- continue;
- }
-#endif
- ret = synthesize_probe_event(&session.probes[j]);
- if (ret == -E2BIG)
- semantic_error("probe point is too long.");
- else if (ret < 0)
- die("Failed to synthesize a probe point.");
- }
-
-#ifndef NO_LIBDWARF
- if (!session.need_dwarf)
- goto setup_probes;
+#ifdef NO_LIBDWARF
+ semantic_error("Debuginfo-analysis is not supported");
+#else /* !NO_LIBDWARF */
+ pr_info("Some probes require debuginfo.\n");

if (session.vmlinux)
fd = open(session.vmlinux, O_RDONLY);
else
fd = open_default_vmlinux();
- if (fd < 0)
- die("Could not open vmlinux/module file.");
+ if (fd < 0) {
+ if (session.need_dwarf)
+ die("Could not open vmlinux/module file.");
+
+ pr_warning("Could not open vmlinux/module file."
+ " Try to use symbols.\n");
+ goto end_dwarf;
+ }

/* Searching probe points */
for (j = 0; j < session.nr_probe; j++) {
@@ -386,14 +374,35 @@ int cmd_probe(int argc, const char **argv, const char *prefix __used)

lseek(fd, SEEK_SET, 0);
ret = find_probepoint(fd, pp);
- if (ret <= 0)
- die("No probe point found.\n");
+ if (ret < 0) {
+ if (session.need_dwarf)
+ die("Could not analyze debuginfo.");
+
+ pr_warning("An error was occurred in debuginfo"
+ " analysis. Try to use symbols.\n");
+ break;
+ }
+ if (ret == 0) /* No error but failed to find probe point. */
+ die("No probe point found.");
}
close(fd);

-setup_probes:
+end_dwarf:
#endif /* !NO_LIBDWARF */

+ /* Synthesize probes without dwarf */
+ for (j = 0; j < session.nr_probe; j++) {
+ pp = &session.probes[j];
+ if (pp->found) /* This probe is already found. */
+ continue;
+
+ ret = synthesize_probe_event(pp);
+ if (ret == -E2BIG)
+ semantic_error("probe point is too long.");
+ else if (ret < 0)
+ die("Failed to synthesize a probe point.");
+ }
+
/* Settng up probe points */
snprintf(buf, MAX_CMDLEN, "%s/../kprobe_events", debugfs_path);
fd = open(buf, O_WRONLY, O_APPEND);
diff --git a/tools/perf/util/probe-finder.c b/tools/perf/util/probe-finder.c
index 86cead3..f628dee 100644
--- a/tools/perf/util/probe-finder.c
+++ b/tools/perf/util/probe-finder.c
@@ -687,9 +687,11 @@ int find_probepoint(int fd, struct probe_point *pp)
struct probe_finder pf = {.pp = pp};

ret = dwarf_init(fd, DW_DLC_READ, 0, 0, &__dw_debug, &__dw_error);
- if (ret != DW_DLV_OK)
- die("Not found dwarf info in the vmlinux"
- " - please rebuild with CONFIG_DEBUG_INFO.\n");
+ if (ret != DW_DLV_OK) {
+ pr_warning("Not found dwarf info in the vmlinux"
+ " - please rebuild with CONFIG_DEBUG_INFO.\n");
+ return -ENOENT;
+ }

pp->found = 0;
while (++cu_number) {