Re: [PATCH 1/5] perf probe: Return a better scope DIE if there is no best scope

[Arnaldo Carvalho de Melo <arnaldo.melo@gmail.com>]

Em Tue, Nov 05, 2019 at 09:16:49AM +0900, Masami Hiramatsu escreveu:
> Make find_best_scope() returns innermost DIE at given address if
> there is no best matched scope DIE. Since Gcc sometimes generates
> intuitively strange line info which is out of inlined function
> address range, we need this fixup.
> 
> Without this, sometimes perf probe failed to probe on a line
> inside an inlined function.
>   # perf probe -D ksys_open:3
>   Failed to find scope of probe point.
>     Error: Failed to add events.
> 
> With this fix, perf probe can probe it.
>   # perf probe -D ksys_open:3
>   p:probe/ksys_open _text+25707308
>   p:probe/ksys_open_1 _text+25710596
>   p:probe/ksys_open_2 _text+25711114
>   p:probe/ksys_open_3 _text+25711343
>   p:probe/ksys_open_4 _text+25714058
>   p:probe/ksys_open_5 _text+2819653
>   p:probe/ksys_open_6 _text+2819701

Thanks, tested before and after and applied,

- Arnaldo
 
> Signed-off-by: Masami Hiramatsu <mhiramat@kernel.org>
> ---
>  tools/perf/util/probe-finder.c |   17 ++++++++++++++++-
>  1 file changed, 16 insertions(+), 1 deletion(-)
> 
> diff --git a/tools/perf/util/probe-finder.c b/tools/perf/util/probe-finder.c
> index f441e0174334..9ecea45da4ca 100644
> --- a/tools/perf/util/probe-finder.c
> +++ b/tools/perf/util/probe-finder.c
> @@ -744,6 +744,16 @@ static int find_best_scope_cb(Dwarf_Die *fn_die, void *data)
>  	return 0;
>  }
>  
> +/* Return innermost DIE */
> +static int find_inner_scope_cb(Dwarf_Die *fn_die, void *data)
> +{
> +	struct find_scope_param *fsp = data;
> +
> +	memcpy(fsp->die_mem, fn_die, sizeof(Dwarf_Die));
> +	fsp->found = true;
> +	return 1;
> +}
> +
>  /* Find an appropriate scope fits to given conditions */
>  static Dwarf_Die *find_best_scope(struct probe_finder *pf, Dwarf_Die *die_mem)
>  {
> @@ -755,8 +765,13 @@ static Dwarf_Die *find_best_scope(struct probe_finder *pf, Dwarf_Die *die_mem)
>  		.die_mem = die_mem,
>  		.found = false,
>  	};
> +	int ret;
>  
> -	cu_walk_functions_at(&pf->cu_die, pf->addr, find_best_scope_cb, &fsp);
> +	ret = cu_walk_functions_at(&pf->cu_die, pf->addr, find_best_scope_cb,
> +				   &fsp);
> +	if (!ret && !fsp.found)
> +		cu_walk_functions_at(&pf->cu_die, pf->addr,
> +				     find_inner_scope_cb, &fsp);
>  
>  	return fsp.found ? die_mem : NULL;
>  }

-- 

- Arnaldo