On 03/17/18 03:07 PM, Luke Diamand wrote:
> In b56e4cb88989f82988a6a70acb32e187e88b5cac ("ALIAS dwarf symbols"),
> dwarf_find_debug_frame() went from being public to hidden. I could be
> wrong about this, but I think this may stop perf from using libunwind.
>
> This is the change:
>
> -int
> +HIDDEN int
> dwarf_find_debug_frame (int found, unw_dyn_info_t *di_debug, unw_word_t ip,
>
> Here's the code in tools/build/feature/test-libunwind-debug-frame.c
>
> extern int
> UNW_OBJ(dwarf_find_debug_frame) (int found, unw_dyn_info_t *di_debug,
> unw_word_t ip, unw_word_t segbase,
> const char *obj_name, unw_word_t start,
> unw_word_t end);
>
> #define dwarf_find_debug_frame UNW_OBJ(dwarf_find_debug_frame)
>
> int main(void) {
> dwarf_find_debug_frame(0, NULL, 0, 0, NULL, 0, 0);
> return 0;
> }
>
> (And it gets used inside perf to actually find the debug frames).
>
> I'm not a perf expert *or* a libunwind expert. Experimentally I find
> that with libunwind 1.3 I don't get callstacks in perf unless I get
> rid of the HIDDEN.
Nope, looks like a mistake that should be reverted, when removing
PROTECTED visibility. Thanks for pointing it out.
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