Re: [PATCH V2 2/3] perf symbols: improve abi compliance in arm mapping symbols handling

[Russell King - ARM Linux]

On Wed, Jan 21, 2015 at 08:52:57PM -0800, Victor Kamensky wrote:
> Both Arm and Aarch64 ELF ABI allow mapping symbols be in from
> either "$d" or "$d.<any>". But current code that handles mapping
> symbols only deals with the first, dollar character and a single
> letter, case.
> 
> The patch adds handling of the second case with period
> followed by any characters.
> 
> Suggested-by: Russell King <linux@xxxxxxxxxxxxxxxx>
> Suggested-by: Will Deacon <will.deacon@xxxxxxx>
> Signed-off-by: Victor Kamensky <victor.kamensky@xxxxxxxxxx>
> Acked-by: Will Deacon <will.deacon@xxxxxxx>
> Cc: Peter Zijlstra <a.p.zijlstra@xxxxxxxxx>
> Cc: Paul Mackerras <paulus@xxxxxxxxx>
> Cc: Ingo Molnar <mingo@xxxxxxxxxx>
> Cc: Arnaldo Carvalho de Melo <acme@xxxxxxxxxx>
> Cc: Adrian Hunter <adrian.hunter@xxxxxxxxx>
> Cc: Jiri Olsa <jolsa@xxxxxxxxxx>
> Cc: Namhyung Kim <namhyung@xxxxxxxxxx>
> Cc: Avi Kivity <avi@xxxxxxxxxxxxxxxxxxxx>
> Cc: Masami Hiramatsu <masami.hiramatsu.pt@xxxxxxxxxxx>
> Cc: Anton Blanchard <anton@xxxxxxxxx>
> Cc: David Ahern <dsahern@xxxxxxxxx>
> Cc: Dave Martin <Dave.Martin@xxxxxxx>
> ---
>  tools/perf/util/symbol-elf.c | 9 ++++-----
>  1 file changed, 4 insertions(+), 5 deletions(-)
> 
> diff --git a/tools/perf/util/symbol-elf.c b/tools/perf/util/symbol-elf.c
> index 1e188dd..7fd35d6 100644
> --- a/tools/perf/util/symbol-elf.c
> +++ b/tools/perf/util/symbol-elf.c
> @@ -857,17 +857,16 @@ int dso__load_sym(struct dso *dso, struct map *map,
>  		 * don't identify functions, so will confuse the profile
>  		 * output: */
>  		if (ehdr.e_machine == EM_ARM) {
> -			if (!strcmp(elf_name, "$a") ||
> -			    !strcmp(elf_name, "$d") ||
> -			    !strcmp(elf_name, "$t"))
> +			if (elf_name[0] == '$' && strchr("adt", elf_name[1])
> +			    && (elf_name[2] == '\0' || elf_name[2] == '.'))
>  				continue;
>  		}
>  		/* Reject Aarch64 ELF "mapping symbols": these aren't unique and
>  		 * don't identify functions, so will confuse the profile
>  		 * output: */
>  		if (ehdr.e_machine == EM_AARCH64) {
> -			if (!strcmp(elf_name, "$x") ||
> -			    !strcmp(elf_name, "$d"))
> +			if (elf_name[0] == '$' && strchr("dx", elf_name[1])
> +			    && (elf_name[2] == '\0' || elf_name[2] == '.'))
>  				continue;
>  		}

Why not fix this first?  Then, all you'd need to do would be to change
the test for EM_ARM to EM_ARM or EM_AARCH64, and add the 'x' into the
strchr() string.

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