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>

diff --git a/tools/perf/builtin-probe.c b/tools/perf/builtin-probe.c
index 65bcaed..d111a93 100644 (file)
--- 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);

diff --git a/tools/perf/util/probe-finder.c b/tools/perf/util/probe-finder.c
index 35d5a69..293cdfc 100644 (file)
--- a/tools/perf/util/probe-finder.c
+++ b/tools/perf/util/probe-finder.c
@@ -687,8 +687,10 @@ 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("No dwarf info found in the vmlinux - please rebuild with CONFIG_DEBUG_INFO.\n");
+       if (ret != DW_DLV_OK) {
+               pr_warning("No dwarf info found in the vmlinux - please rebuild with CONFIG_DEBUG_INFO.\n");
+               return -ENOENT;
+       }
 
        pp->found = 0;
        while (++cu_number) {