Re: [PATCH perf/core 07/10] perf probe: Support @BUILDID or @FILE suffix for SDT events

[Arnaldo Carvalho de Melo <acme@kernel.org>]

Em Tue, Jul 12, 2016 at 07:05:37PM +0900, Masami Hiramatsu escreveu:
> Support @BUILDID or @FILE suffix for SDT events. This allows
> perf to add probes on SDTs/pre-cached events on given FILE
> or the file which has given BUILDID (also, this complements
> BUILDID.)
> For example, both gcc and libstdc++ has same SDTs as below.
> If you would like to add a probe on sdt_libstdcxx:catch on gcc,
> you can do as below.

Ok, how to add those entries?

[root@jouet hello_world]# perf probe -x /usr/bin/gcc -a %sdt_gcc:\*
  Error: Failed to add events.
[root@jouet hello_world]# perf probe --verbose -x /usr/bin/gcc -a %sdt_gcc:\*
probe-definition(0): %sdt_gcc:*
0 arguments
symbol:throw file:(null) line:0 offset:0 return:0 lazy:(null)
symbol:rethrow file:(null) line:0 offset:0 return:0 lazy:(null)
symbol:catch file:(null) line:0 offset:0 return:0 lazy:(null)
symbol:unwind file:(null) line:0 offset:0 return:0 lazy:(null)
  Error: Failed to add events. Reason: No such file or directory (Code: -2)
[root@jouet hello_world]# 

Can those messages be improved? What am I missing?
 
>   ----
>   # perf list sdt | tail -n 6
>     sdt_libstdcxx:catch@/usr/bin/gcc(0cc207fc4b27)     [SDT event]
>     sdt_libstdcxx:catch@/usr/lib64/libstdc++.so.6.0.20(91c7a88fdf49)
>     sdt_libstdcxx:rethrow@/usr/bin/gcc(0cc207fc4b27)   [SDT event]
>     sdt_libstdcxx:rethrow@/usr/lib64/libstdc++.so.6.0.20(91c7a88fdf49)
>     sdt_libstdcxx:throw@/usr/bin/gcc(0cc207fc4b27)     [SDT event]
>     sdt_libstdcxx:throw@/usr/lib64/libstdc++.so.6.0.20(91c7a88fdf49)
>   # perf probe -a %sdt_libstdcxx:catch@0cc
>   Added new event:
>     sdt_libstdcxx:catch  (on %catch in /usr/bin/gcc)
> 
>   You can now use it in all perf tools, such as:
> 
>   	perf record -e sdt_libstdcxx:catch -aR sleep 1
>   ----
> 
> Signed-off-by: Masami Hiramatsu <mhiramat@kernel.org>
> ---
>  Changes in v12:
>   - Rename strlist__for_each to strlist__for_each_entry.
> ---
>  tools/perf/util/build-id.c    |   43 +++++++++++++++++++++++++++++++++++++++++
>  tools/perf/util/build-id.h    |    1 +
>  tools/perf/util/probe-event.c |   17 ++++++++++++++--
>  3 files changed, 59 insertions(+), 2 deletions(-)
> 
> diff --git a/tools/perf/util/build-id.c b/tools/perf/util/build-id.c
> index 8e86a83..e59003e 100644
> --- a/tools/perf/util/build-id.c
> +++ b/tools/perf/util/build-id.c
> @@ -523,6 +523,49 @@ err_out:
>  	goto out_free;
>  }
>  
> +static bool str_is_build_id(const char *maybe_sbuild_id, size_t len)
> +{
> +	size_t i;
> +
> +	for (i = 0; i < len; i++) {
> +		if (!isxdigit(maybe_sbuild_id[i]))
> +			return false;
> +	}
> +	return true;
> +}
> +
> +/* Return the valid complete build-id */
> +char *build_id_cache__complement(const char *incomplete_sbuild_id)
> +{
> +	struct strlist *bidlist;
> +	struct str_node *nd, *cand = NULL;
> +	char *sbuild_id = NULL;
> +	size_t len = strlen(incomplete_sbuild_id);
> +
> +	if (len >= SBUILD_ID_SIZE ||
> +	    !str_is_build_id(incomplete_sbuild_id, len))
> +		return NULL;
> +
> +	bidlist = build_id_cache__list_all(true);
> +	if (!bidlist)
> +		return NULL;
> +
> +	strlist__for_each_entry(nd, bidlist) {
> +		if (strncmp(nd->s, incomplete_sbuild_id, len) != 0)
> +			continue;
> +		if (cand) {	/* Error: There are more than 2 candidates. */
> +			cand = NULL;
> +			break;
> +		}
> +		cand = nd;
> +	}
> +	if (cand)
> +		sbuild_id = strdup(cand->s);
> +	strlist__delete(bidlist);
> +
> +	return sbuild_id;
> +}
> +
>  char *build_id_cache__cachedir(const char *sbuild_id, const char *name,
>  			       bool is_kallsyms, bool is_vdso)
>  {
> diff --git a/tools/perf/util/build-id.h b/tools/perf/util/build-id.h
> index 64e740f..d279906 100644
> --- a/tools/perf/util/build-id.h
> +++ b/tools/perf/util/build-id.h
> @@ -35,6 +35,7 @@ char *build_id_cache__linkname(const char *sbuild_id, char *bf, size_t size);
>  char *build_id_cache__cachedir(const char *sbuild_id, const char *name,
>  			       bool is_kallsyms, bool is_vdso);
>  struct strlist *build_id_cache__list_all(bool validonly);
> +char *build_id_cache__complement(const char *incomplete_sbuild_id);
>  int build_id_cache__list_build_ids(const char *pathname,
>  				   struct strlist **result);
>  bool build_id_cache__cached(const char *sbuild_id);
> diff --git a/tools/perf/util/probe-event.c b/tools/perf/util/probe-event.c
> index 679aa6b..0dadaa3 100644
> --- a/tools/perf/util/probe-event.c
> +++ b/tools/perf/util/probe-event.c
> @@ -1251,8 +1251,21 @@ static int parse_perf_probe_point(char *arg, struct perf_probe_event *pev)
>  	ptr = strpbrk(arg, ";=@+%");
>  	if (pev->sdt) {
>  		if (ptr) {
> -			semantic_error("%s must contain only an SDT event name.\n", arg);
> -			return -EINVAL;
> +			if (*ptr != '@') {
> +				semantic_error("%s must be an SDT name.\n",
> +					       arg);
> +				return -EINVAL;
> +			}
> +			/* This must be a target file name or build id */
> +			tmp = build_id_cache__complement(ptr + 1);
> +			if (tmp) {
> +				pev->target = build_id_cache__origname(tmp);
> +				free(tmp);
> +			} else
> +				pev->target = strdup(ptr + 1);
> +			if (!pev->target)
> +				return -ENOMEM;
> +			*ptr = '\0';
>  		}
>  		ret = parse_perf_probe_event_name(&arg, pev);
>  		if (ret == 0) {