perf symbols: Use only --vmlinux if specified

Found while analysing a perf.data file collected on an ARM
machine where an explicitely specified vmlinux was being
disregarded.

Reported-by: Jamie Iles <jamie.iles@picochip.com>
Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>
Cc: Frédéric Weisbecker <fweisbec@gmail.com>
Cc: Mike Galbraith <efault@gmx.de>
Cc: Peter Zijlstra <a.p.zijlstra@chello.nl>
Cc: Paul Mackerras <paulus@samba.org>
LKML-Reference: <1263904574-30732-2-git-send-email-acme@infradead.org>
Signed-off-by: Ingo Molnar <mingo@elte.hu>

1 files changed, 41 insertions, 26 deletions

diff --git a/tools/perf/util/symbol.c b/tools/perf/util/symbol.c
index a4e745934584..b6ab23dd5f9f 100644
--- a/tools/perf/util/symbol.c
+++ b/tools/perf/util/symbol.c
@@ -1572,7 +1572,7 @@ static int dso__load_vmlinux(struct dso *self, struct map *map,
                 return -1;
 
         dso__set_loaded(self, map->type);
-        err = dso__load_sym(self, map, session, self->long_name, fd, filter, 1, 0);
+        err = dso__load_sym(self, map, session, vmlinux, fd, filter, 1, 0);
         close(fd);
 
         return err;
@@ -1584,6 +1584,26 @@ static int dso__load_kernel_sym(struct dso *self, struct map *map,
         int err;
         const char *kallsyms_filename = NULL;
         char *kallsyms_allocated_filename = NULL;
+        /*
+         * Step 1: if the user specified a vmlinux filename, use it and only
+         * it, reporting errors to the user if it cannot be used.
+         *
+         * For instance, try to analyse an ARM perf.data file _without_ a
+         * build-id, or if the user specifies the wrong path to the right
+         * vmlinux file, obviously we can't fallback to another vmlinux (a
+         * x86_86 one, on the machine where analysis is being performed, say),
+         * or worse, /proc/kallsyms.
+         *
+         * If the specified file _has_ a build-id and there is a build-id
+         * section in the perf.data file, we will still do the expected
+         * validation in dso__load_vmlinux and will bail out if they don't
+         * match.
+         */
+        if (symbol_conf.vmlinux_name != NULL) {
+                err = dso__load_vmlinux(self, map, session,
+                                        symbol_conf.vmlinux_name, filter);
+                goto out_try_fixup;
+        }
 
         if (vmlinux_path != NULL) {
                 int i;
@@ -1618,46 +1638,41 @@ static int dso__load_kernel_sym(struct dso *self, struct map *map,
                                 goto do_kallsyms;
                         }
                 }
-
+                /*
+                 * Now look if we have it on the build-id cache in
+                 * $HOME/.debug/[kernel.kallsyms].
+                 */
                 build_id__sprintf(self->build_id, sizeof(self->build_id),
                                   sbuild_id);
 
                 if (asprintf(&kallsyms_allocated_filename,
                              "%s/.debug/[kernel.kallsyms]/%s",
-                             getenv("HOME"), sbuild_id) != -1) {
-                        if (access(kallsyms_filename, F_OK)) {
-                                kallsyms_filename = kallsyms_allocated_filename;
-                                goto do_kallsyms;
-                        }
+                             getenv("HOME"), sbuild_id) == -1)
+                        return -1;
+
+                if (access(kallsyms_filename, F_OK)) {
                         free(kallsyms_allocated_filename);
-                        kallsyms_allocated_filename = NULL;
+                        return -1;
                 }
 
-                goto do_vmlinux;
-        }
-
-        if (self->long_name[0] == '[') {
+                kallsyms_filename = kallsyms_allocated_filename;
+        } else {
+                /*
+                 * Last resort, if we don't have a build-id and couldn't find
+                 * any vmlinux file, try the running kernel kallsyms table.
+                 */
                 kallsyms_filename = "/proc/kallsyms";
-                goto do_kallsyms;
         }
 
-do_vmlinux:
-        err = dso__load_vmlinux(self, map, session, self->long_name, filter);
-        if (err <= 0) {
-                if (self->has_build_id)
-                        return -1;
-
-                pr_info("The file %s cannot be used, "
-                        "trying to use /proc/kallsyms...", self->long_name);
 do_kallsyms:
-                err = dso__load_kallsyms(self, kallsyms_filename, map, session, filter);
-                if (err > 0 && kallsyms_filename == NULL)
-                        dso__set_long_name(self, strdup("[kernel.kallsyms]"));
-                free(kallsyms_allocated_filename);
-        }
+        err = dso__load_kallsyms(self, kallsyms_filename, map, session, filter);
+        free(kallsyms_allocated_filename);
 
+out_try_fixup:
         if (err > 0) {
 out_fixup:
+                if (kallsyms_filename == NULL)
+                        dso__set_long_name(self, strdup("[kernel.kallsyms]"));
                 map__fixup_start(map);
                 map__fixup_end(map);
         }