perf tools: Disable kernel symbol demangling by default

Some Linux symbols (for example __vt_event_wait) are interpreted by the
demangler as C++ mangled names, which of course they aren't.

Disable kernel symbol demangling by default to avoid this, and allow
enabling it with a new option --demangle-kernel for those who wish it.

Reported-by: Jiri Olsa <jolsa@redhat.com>
Signed-off-by: Avi Kivity <avi@cloudius-systems.com>
Acked-by: Jiri Olsa <jolsa@kernel.org>
Cc: Jiri Olsa <jolsa@redhat.com>
Link: http://lkml.kernel.org/r/1410581705-26968-1-git-send-email-avi@cloudius-systems.com
Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>

1 files changed, 6 insertions, 1 deletions

diff --git a/tools/perf/util/symbol-elf.c b/tools/perf/util/symbol-elf.c
index 9fb5e9e9f161..9c9b27fbc78d 100644
--- a/tools/perf/util/symbol-elf.c
+++ b/tools/perf/util/symbol-elf.c
@@ -680,6 +680,11 @@ static u64 ref_reloc(struct kmap *kmap)
         return 0;
 }
 
+static bool want_demangle(bool is_kernel_sym)
+{
+        return is_kernel_sym ? symbol_conf.demangle_kernel : symbol_conf.demangle;
+}
+
 int dso__load_sym(struct dso *dso, struct map *map,
                   struct symsrc *syms_ss, struct symsrc *runtime_ss,
                   symbol_filter_t filter, int kmodule)
@@ -938,7 +943,7 @@ new_symbol:
                  * DWARF DW_compile_unit has this, but we don't always have access
                  * to it...
                  */
-                if (symbol_conf.demangle) {
+                if (want_demangle(dso->kernel || kmodule)) {
                         int demangle_flags = DMGL_NO_OPTS;
                         if (verbose)
                                 demangle_flags = DMGL_PARAMS | DMGL_ANSI;