From d0b0d0406fe6743e734e1ba780155f8db5f713e6 Mon Sep 17 00:00:00 2001 From: Anton Blanchard Date: Tue, 9 Sep 2014 08:59:29 +1000 Subject: [PATCH] perf symbols: Ignore stripped vmlinux and fallback to kallsyms If a vmlinux is stripped, perf will use it and ignore kallsyms. We end up with useless profiles where everything maps to a few runtime symbols: 63.39% swapper [kernel.kallsyms] [k] hcall_real_table 4.90% beam.smp [kernel.kallsyms] [k] hcall_real_table 4.44% beam.smp [kernel.kallsyms] [k] __sched_text_start 3.72% beam.smp [kernel.kallsyms] [k] __run_at_kexec Detect this case and fallback to using kallsyms. This fixes the issue: 62.81% swapper [kernel.kallsyms] [k] snooze_loop 4.44% beam.smp [kernel.kallsyms] [k] __schedule 0.91% beam.smp [kernel.kallsyms] [k] _switch 0.73% beam.smp [kernel.kallsyms] [k] put_prev_entity Signed-off-by: Anton Blanchard Acked-by: Namhyung Kim Cc: Ingo Molnar Cc: Paul Mackerras Cc: Peter Zijlstra Link: http://lkml.kernel.org/r/20140909085929.4a5a81f0@kryten Signed-off-by: Arnaldo Carvalho de Melo --- tools/perf/util/symbol-elf.c | 8 ++++++++ 1 file changed, 8 insertions(+) diff --git a/tools/perf/util/symbol-elf.c b/tools/perf/util/symbol-elf.c index 9c9b27fbc78d..2a92e10317c5 100644 --- a/tools/perf/util/symbol-elf.c +++ b/tools/perf/util/symbol-elf.c @@ -717,6 +717,14 @@ int dso__load_sym(struct dso *dso, struct map *map, symbols__delete(&dso->symbols[map->type]); if (!syms_ss->symtab) { + /* + * If the vmlinux is stripped, fail so we will fall back + * to using kallsyms. The vmlinux runtime symbols aren't + * of much use. + */ + if (dso->kernel) + goto out_elf_end; + syms_ss->symtab = syms_ss->dynsym; syms_ss->symshdr = syms_ss->dynshdr; } -- 2.20.1