perf annotate: Introduce strerror for handling symbol__disassemble() errors

We were just using pr_error() which makes it difficult for non stdio UIs
to provide errors using its widgets, as they need to somehow catch what
was passed to pr_error().

Fix it by introducing a __strerror() interface like the ones used
elsewhere, for instance target__strerror().

This is just the initial step, more work will be done, but first some
error handling bugs noticed while working on this need to be dealt with.

Cc: Adrian Hunter <adrian.hunter@intel.com>
Cc: David Ahern <dsahern@gmail.com>
Cc: Jiri Olsa <jolsa@kernel.org>
Cc: Namhyung Kim <namhyung@kernel.org>
Cc: Wang Nan <wangnan0@huawei.com>
Link: http://lkml.kernel.org/n/tip-dgd22zl2xg7x4vcnoa83jxfb@git.kernel.org
Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>

5 files changed, 78 insertions, 31 deletions

diff --git a/tools/perf/builtin-top.c b/tools/perf/builtin-top.c
index 823dbbbf82a9..418ed94756d3 100644
--- a/tools/perf/builtin-top.c
+++ b/tools/perf/builtin-top.c
@@ -132,6 +132,10 @@ static int perf_top__parse_source(struct perf_top *top, struct hist_entry *he)
         if (err == 0) {
 out_assign:
                 top->sym_filter_entry = he;
+        } else {
+                char msg[BUFSIZ];
+                symbol__strerror_disassemble(sym, map, err, msg, sizeof(msg));
+                pr_err("Couldn't annotate %s: %s\n", sym->name, msg);
         }
 
         pthread_mutex_unlock(&notes->lock);
diff --git a/tools/perf/ui/browsers/annotate.c b/tools/perf/ui/browsers/annotate.c
index f4d6a8a962af..2e2d10022355 100644
--- a/tools/perf/ui/browsers/annotate.c
+++ b/tools/perf/ui/browsers/annotate.c
@@ -1026,7 +1026,7 @@ int symbol__tui_annotate(struct symbol *sym, struct map *map,
                         .use_navkeypressed = true,
                 },
         };
-        int ret = -1;
+        int ret = -1, err;
         int nr_pcnt = 1;
         size_t sizeof_bdl = sizeof(struct browser_disasm_line);
 
@@ -1050,8 +1050,11 @@ int symbol__tui_annotate(struct symbol *sym, struct map *map,
                   (nr_pcnt - 1);
         }
 
-        if (symbol__disassemble(sym, map, sizeof_bdl) < 0) {
-                ui__error("%s", ui_helpline__last_msg);
+        err = symbol__disassemble(sym, map, sizeof_bdl);
+        if (err) {
+                char msg[BUFSIZ];
+                symbol__strerror_disassemble(sym, map, err, msg, sizeof(msg));
+                ui__error("Couldn't annotate %s:\n%s", sym->name, msg);
                 goto out_free_offsets;
         }
 
diff --git a/tools/perf/ui/gtk/annotate.c b/tools/perf/ui/gtk/annotate.c
index 35e4b9e28c8d..42d319927762 100644
--- a/tools/perf/ui/gtk/annotate.c
+++ b/tools/perf/ui/gtk/annotate.c
@@ -162,12 +162,16 @@ static int symbol__gtk_annotate(struct symbol *sym, struct map *map,
         GtkWidget *notebook;
         GtkWidget *scrolled_window;
         GtkWidget *tab_label;
+        int err;
 
         if (map->dso->annotate_warned)
                 return -1;
 
-        if (symbol__disassemble(sym, map, 0) < 0) {
-                ui__error("%s", ui_helpline__current);
+        err = symbol__disassemble(sym, map, 0);
+        if (err) {
+                char msg[BUFSIZ];
+                symbol__strerror_disassemble(sym, map, err, msg, sizeof(msg));
+                ui__error("Couldn't annotate %s: %s\n", sym->name, msg);
                 return -1;
         }
 
diff --git a/tools/perf/util/annotate.c b/tools/perf/util/annotate.c
index 4f47b6069197..4982ed487e96 100644
--- a/tools/perf/util/annotate.c
+++ b/tools/perf/util/annotate.c
@@ -1123,6 +1123,45 @@ static void delete_last_nop(struct symbol *sym)
         }
 }
 
+int symbol__strerror_disassemble(struct symbol *sym __maybe_unused, struct map *map,
+                              int errnum, char *buf, size_t buflen)
+{
+        struct dso *dso = map->dso;
+
+        BUG_ON(buflen == 0);
+
+        if (errnum >= 0) {
+                str_error_r(errnum, buf, buflen);
+                return 0;
+        }
+
+        switch (errnum) {
+        case SYMBOL_ANNOTATE_ERRNO__NO_VMLINUX: {
+                char bf[SBUILD_ID_SIZE + 15] = " with build id ";
+                char *build_id_msg = NULL;
+
+                if (dso->has_build_id) {
+                        build_id__sprintf(dso->build_id,
+                                          sizeof(dso->build_id), bf + 15);
+                        build_id_msg = bf;
+                }
+                scnprintf(buf, buflen,
+                          "No vmlinux file%s\nwas found in the path.\n\n"
+                          "Note that annotation using /proc/kcore requires CAP_SYS_RAWIO capability.\n\n"
+                          "Please use:\n\n"
+                          "  perf buildid-cache -vu vmlinux\n\n"
+                          "or:\n\n"
+                          "  --vmlinux vmlinux\n", build_id_msg ?: "");
+        }
+                break;
+        default:
+                scnprintf(buf, buflen, "Internal error: Invalid %d error code\n", errnum);
+                break;
+        }
+
+        return 0;
+}
+
 int symbol__disassemble(struct symbol *sym, struct map *map, size_t privsize)
 {
         struct dso *dso = map->dso;
@@ -1143,11 +1182,8 @@ int symbol__disassemble(struct symbol *sym, struct map *map, size_t privsize)
                 symbol__join_symfs(symfs_filename, filename);
 
         if (filename == NULL) {
-                if (dso->has_build_id) {
-                        pr_err("Can't annotate %s: not enough memory\n",
-                               sym->name);
-                        return -ENOMEM;
-                }
+                if (dso->has_build_id)
+                        return ENOMEM;
                 goto fallback;
         } else if (dso__is_kcore(dso)) {
                 goto fallback;
@@ -1168,27 +1204,7 @@ fallback:
 
         if (dso->symtab_type == DSO_BINARY_TYPE__KALLSYMS &&
             !dso__is_kcore(dso)) {
-                char bf[SBUILD_ID_SIZE + 15] = " with build id ";
-                char *build_id_msg = NULL;
-
-                if (dso->annotate_warned)
-                        goto out_free_filename;
-
-                if (dso->has_build_id) {
-                        build_id__sprintf(dso->build_id,
-                                          sizeof(dso->build_id), bf + 15);
-                        build_id_msg = bf;
-                }
-                err = -ENOENT;
-                dso->annotate_warned = 1;
-                pr_err("Can't annotate %s:\n\n"
-                       "No vmlinux file%s\nwas found in the path.\n\n"
-                       "Note that annotation using /proc/kcore requires CAP_SYS_RAWIO capability.\n\n"
-                       "Please use:\n\n"
-                       "  perf buildid-cache -vu vmlinux\n\n"
-                       "or:\n\n"
-                       "  --vmlinux vmlinux\n",
-                       sym->name, build_id_msg ?: "");
+                err = SYMBOL_ANNOTATE_ERRNO__NO_VMLINUX;
                 goto out_free_filename;
         }
 
diff --git a/tools/perf/util/annotate.h b/tools/perf/util/annotate.h
index b0750d8bee1f..f67ccb027561 100644
--- a/tools/perf/util/annotate.h
+++ b/tools/perf/util/annotate.h
@@ -157,6 +157,26 @@ void symbol__annotate_zero_histograms(struct symbol *sym);
 
 int symbol__disassemble(struct symbol *sym, struct map *map, size_t privsize);
 
+enum symbol_disassemble_errno {
+        SYMBOL_ANNOTATE_ERRNO__SUCCESS          = 0,
+
+        /*
+         * Choose an arbitrary negative big number not to clash with standard
+         * errno since SUS requires the errno has distinct positive values.
+         * See 'Issue 6' in the link below.
+         *
+         * http://pubs.opengroup.org/onlinepubs/9699919799/basedefs/errno.h.html
+         */
+        __SYMBOL_ANNOTATE_ERRNO__START          = -10000,
+
+        SYMBOL_ANNOTATE_ERRNO__NO_VMLINUX       = __SYMBOL_ANNOTATE_ERRNO__START,
+
+        __SYMBOL_ANNOTATE_ERRNO__END,
+};
+
+int symbol__strerror_disassemble(struct symbol *sym, struct map *map,
+                                 int errnum, char *buf, size_t buflen);
+
 int symbol__annotate_init(struct map *map, struct symbol *sym);
 int symbol__annotate_printf(struct symbol *sym, struct map *map,
                             struct perf_evsel *evsel, bool full_paths,