perf/probes: Fall back to non-dwarf if possible

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>
Acked-by: Frederic Weisbecker <fweisbec@gmail.com>
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: 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>
LKML-Reference: <20091104001229.3454.63987.stgit@harusame>
Signed-off-by: Ingo Molnar <mingo@elte.hu>

1 files changed, 36 insertions, 28 deletions

diff --git a/tools/perf/builtin-probe.c b/tools/perf/builtin-probe.c
index 65bcaed0ef49..d111a93f2209 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 +374,34 @@ 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 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);