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 <[email protected]>
---
Index: b/tools/perf/util/symbol-elf.c
===================================================================
--- a/tools/perf/util/symbol-elf.c
+++ b/tools/perf/util/symbol-elf.c
@@ -712,6 +712,14 @@ int dso__load_sym(struct dso *dso, struc
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;
}
--
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