Date:	Fri, 1 Jul 2016 10:51:04 -0300
From:	Arnaldo Carvalho de Melo <acme@...nel.org>
To:	Masami Hiramatsu <mhiramat@...nel.org>
Cc:	linux-kernel@...r.kernel.org, Namhyung Kim <namhyung@...nel.org>,
	Peter Zijlstra <peterz@...radead.org>,
	Ingo Molnar <mingo@...hat.com>,
	Hemant Kumar <hemant@...ux.vnet.ibm.com>,
	Ananth N Mavinakayanahalli <ananth@...ux.vnet.ibm.com>,
	Brendan Gregg <brendan.d.gregg@...il.com>
Subject: Re: [PATCH perf/core v13 02/15] perf probe: Show all cached probes

Em Fri, Jul 01, 2016 at 05:03:26PM +0900, Masami Hiramatsu escreveu:
> From: Masami Hiramatsu <masami.hiramatsu.pt@...achi.com>
> 
> perf probe --list shows all cached probes when --cache
> is given. Each caches are shown with on which binary that
> probed. e.g.
>   -----
>   # perf probe --cache vfs_read \$params

This one works:

# perf probe --cache vfs_read \$params
Added new event:
  probe:vfs_read       (on vfs_read with $params)

You can now use it in all perf tools, such as:

	perf record -e probe:vfs_read -aR sleep 1

#

>   # perf probe --cache -x /lib64/libc-2.17.so getaddrinfo \$params

But this one doesn't and provides a funny message:

[root@...et perf]# perf probe --cache -x /lib64/libc-2.23.so getaddrinfo \$params
Failed to write event: Invalid argument
Please upgrade your kernel to at least 3.14 to have access to feature $params
  Error: Failed to add events.
[root@...et perf]#

[root@...et perf]# uname -a
Linux jouet 4.5.7-300.fc24.x86_64 #1 SMP Wed Jun 8 18:12:45 UTC 2016 x86_64 x86_64 x86_64 GNU/Linux
[root@...et perf]# cat /etc/fedora-release 
Fedora release 24 (Twenty Four)
[root@...et perf]# 

- Arnaldo

>   # perf probe --cache --list
>   [kernel.kallsyms] (1466a0a250b5d0070c6d0f03c5fed30b237970a1):
>   vfs_read $params
>   /usr/lib64/libc-2.17.so (c31ffe7942bfd77b2fca8f9bd5709d387a86d3bc):
>   getaddrinfo $params
>   -----
> Note that $params requires debuginfo.
> 
> Signed-off-by: Masami Hiramatsu <masami.hiramatsu.pt@...achi.com>
> Signed-off-by: Masami Hiramatsu <mhiramat@...nel.org>
> ---
>  Changes in v12:
>   - Rename strlist__for_each to strlist__for_each_entry.
>  Changes in v11:
>   - Make build_id_cache__list_all() returns strlist directly. (no error code)
>   - Harden build_id_cache__list_all() to check directory entries.
>  Changes in v7:
>   - Remove the top '/' from binary name if it is not a regular file.
> ---
>  tools/perf/Documentation/perf-probe.txt |    8 ++
>  tools/perf/builtin-probe.c              |    2 -
>  tools/perf/util/build-id.c              |  108 ++++++++++++++++++++++++++++++-
>  tools/perf/util/build-id.h              |    3 +
>  tools/perf/util/probe-event.c           |    3 +
>  tools/perf/util/probe-file.c            |   66 ++++++++++++++++++-
>  tools/perf/util/probe-file.h            |    1 
>  7 files changed, 184 insertions(+), 7 deletions(-)
> 
> diff --git a/tools/perf/Documentation/perf-probe.txt b/tools/perf/Documentation/perf-probe.txt
> index 947db6f..5a70d45 100644
> --- a/tools/perf/Documentation/perf-probe.txt
> +++ b/tools/perf/Documentation/perf-probe.txt
> @@ -67,7 +67,10 @@ OPTIONS
>  
>  -l::
>  --list[=[GROUP:]EVENT]::
> -	List up current probe events. This can also accept filtering patterns of event names.
> +	List up current probe events. This can also accept filtering patterns of
> +	event names.
> +	When this is used with --cache, perf shows all cached probes instead of
> +	the live probes.
>  
>  -L::
>  --line=::
> @@ -110,8 +113,9 @@ OPTIONS
>  	adding and removal operations.
>  
>  --cache::
> -	Cache the probes (with --add option). Any events which successfully added
> +	(With --add) Cache the probes. Any events which successfully added
>  	are also stored in the cache file.
> +	(With --list) Show cached probes.
>  
>  --max-probes=NUM::
>  	Set the maximum number of probe points for an event. Default is 128.
> diff --git a/tools/perf/builtin-probe.c b/tools/perf/builtin-probe.c
> index 3426232..0bb9084 100644
> --- a/tools/perf/builtin-probe.c
> +++ b/tools/perf/builtin-probe.c
> @@ -44,7 +44,7 @@
>  
>  #define DEFAULT_VAR_FILTER "!__k???tab_* & !__crc_*"
>  #define DEFAULT_FUNC_FILTER "!_*"
> -#define DEFAULT_LIST_FILTER "*:*"
> +#define DEFAULT_LIST_FILTER "*"
>  
>  /* Session management structure */
>  static struct {
> diff --git a/tools/perf/util/build-id.c b/tools/perf/util/build-id.c
> index 62b1473..1c49620 100644
> --- a/tools/perf/util/build-id.c
> +++ b/tools/perf/util/build-id.c
> @@ -165,8 +165,7 @@ retry:
>  	return NULL;
>  }
>  
> -static char *build_id_cache__linkname(const char *sbuild_id, char *bf,
> -				      size_t size)
> +char *build_id_cache__linkname(const char *sbuild_id, char *bf, size_t size)
>  {
>  	char *tmp = bf;
>  	int ret = asnprintf(&bf, size, "%s/.build-id/%.2s/%s", buildid_dir,
> @@ -176,6 +175,36 @@ static char *build_id_cache__linkname(const char *sbuild_id, char *bf,
>  	return bf;
>  }
>  
> +char *build_id_cache__origname(const char *sbuild_id)
> +{
> +	char *linkname;
> +	char buf[PATH_MAX];
> +	char *ret = NULL, *p;
> +	size_t offs = 5;	/* == strlen("../..") */
> +
> +	linkname = build_id_cache__linkname(sbuild_id, NULL, 0);
> +	if (!linkname)
> +		return NULL;
> +
> +	if (readlink(linkname, buf, PATH_MAX) < 0)
> +		goto out;
> +	/* The link should be "../..<origpath>/<sbuild_id>" */
> +	p = strrchr(buf, '/');	/* Cut off the "/<sbuild_id>" */
> +	if (p && (p > buf + offs)) {
> +		*p = '\0';
> +		if (buf[offs + 1] == '[')
> +			offs++;	/*
> +				 * This is a DSO name, like [kernel.kallsyms].
> +				 * Skip the first '/', since this is not the
> +				 * cache of a regular file.
> +				 */
> +		ret = strdup(buf + offs);	/* Skip "../..[/]" */
> +	}
> +out:
> +	free(linkname);
> +	return ret;
> +}
> +
>  static const char *build_id_cache__basename(bool is_kallsyms, bool is_vdso)
>  {
>  	return is_kallsyms ? "kallsyms" : (is_vdso ? "vdso" : "elf");
> @@ -387,6 +416,81 @@ void disable_buildid_cache(void)
>  	no_buildid_cache = true;
>  }
>  
> +static bool lsdir_bid_head_filter(const char *name __maybe_unused,
> +				  struct dirent *d __maybe_unused)
> +{
> +	return (strlen(d->d_name) == 2) &&
> +		isxdigit(d->d_name[0]) && isxdigit(d->d_name[1]);
> +}
> +
> +static bool lsdir_bid_tail_filter(const char *name __maybe_unused,
> +				  struct dirent *d __maybe_unused)
> +{
> +	int i = 0;
> +	while (isxdigit(d->d_name[i]) && i < SBUILD_ID_SIZE - 3)
> +		i++;
> +	return (i == SBUILD_ID_SIZE - 3) && (d->d_name[i] == '\0');
> +}
> +
> +struct strlist *build_id_cache__list_all(void)
> +{
> +	struct strlist *toplist, *linklist = NULL, *bidlist;
> +	struct str_node *nd, *nd2;
> +	char *topdir, *linkdir = NULL;
> +	char sbuild_id[SBUILD_ID_SIZE];
> +
> +	/* Open the top-level directory */
> +	if (asprintf(&topdir, "%s/.build-id/", buildid_dir) < 0)
> +		return NULL;
> +
> +	bidlist = strlist__new(NULL, NULL);
> +	if (!bidlist)
> +		goto out;
> +
> +	toplist = lsdir(topdir, lsdir_bid_head_filter);
> +	if (!toplist) {
> +		pr_debug("Error in lsdir(%s): %d\n", topdir, errno);
> +		/* If there is no buildid cache, return an empty list */
> +		if (errno == ENOENT)
> +			goto out;
> +		goto err_out;
> +	}
> +
> +	strlist__for_each_entry(nd, toplist) {
> +		if (asprintf(&linkdir, "%s/%s", topdir, nd->s) < 0)
> +			goto err_out;
> +		/* Open the lower-level directory */
> +		linklist = lsdir(linkdir, lsdir_bid_tail_filter);
> +		if (!linklist) {
> +			pr_debug("Error in lsdir(%s): %d\n", linkdir, errno);
> +			goto err_out;
> +		}
> +		strlist__for_each_entry(nd2, linklist) {
> +			if (snprintf(sbuild_id, SBUILD_ID_SIZE, "%s%s",
> +				     nd->s, nd2->s) != SBUILD_ID_SIZE - 1)
> +				goto err_out;
> +			if (strlist__add(bidlist, sbuild_id) < 0)
> +				goto err_out;
> +		}
> +		strlist__delete(linklist);
> +		zfree(&linkdir);
> +	}
> +
> +out_free:
> +	strlist__delete(toplist);
> +out:
> +	free(topdir);
> +
> +	return bidlist;
> +
> +err_out:
> +	strlist__delete(linklist);
> +	zfree(&linkdir);
> +	strlist__delete(bidlist);
> +	bidlist = NULL;
> +	goto out_free;
> +}
> +
>  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 d8c7f2f..b742e27 100644
> --- a/tools/perf/util/build-id.h
> +++ b/tools/perf/util/build-id.h
> @@ -30,8 +30,11 @@ bool perf_session__read_build_ids(struct perf_session *session, bool with_hits);
>  int perf_session__write_buildid_table(struct perf_session *session, int fd);
>  int perf_session__cache_build_ids(struct perf_session *session);
>  
> +char *build_id_cache__origname(const char *sbuild_id);
> +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(void);
>  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 47b6b8b..f81b5dd 100644
> --- a/tools/perf/util/probe-event.c
> +++ b/tools/perf/util/probe-event.c
> @@ -2366,6 +2366,9 @@ int show_perf_probe_events(struct strfilter *filter)
>  
>  	setup_pager();
>  
> +	if (probe_conf.cache)
> +		return probe_cache__show_all_caches(filter);
> +
>  	ret = init_probe_symbol_maps(false);
>  	if (ret < 0)
>  		return ret;
> diff --git a/tools/perf/util/probe-file.c b/tools/perf/util/probe-file.c
> index a94ee47..156e3d8 100644
> --- a/tools/perf/util/probe-file.c
> +++ b/tools/perf/util/probe-file.c
> @@ -367,10 +367,17 @@ static int probe_cache__open(struct probe_cache *pcache, const char *target)
>  {
>  	char cpath[PATH_MAX];
>  	char sbuildid[SBUILD_ID_SIZE];
> -	char *dir_name;
> +	char *dir_name = NULL;
>  	bool is_kallsyms = !target;
>  	int ret, fd;
>  
> +	if (target && build_id_cache__cached(target)) {
> +		/* This is a cached buildid */
> +		strncpy(sbuildid, target, SBUILD_ID_SIZE);
> +		dir_name = build_id_cache__linkname(sbuildid, NULL, 0);
> +		goto found;
> +	}
> +
>  	if (target)
>  		ret = filename__sprintf_build_id(target, sbuildid);
>  	else {
> @@ -394,8 +401,11 @@ static int probe_cache__open(struct probe_cache *pcache, const char *target)
>  
>  	dir_name = build_id_cache__cachedir(sbuildid, target, is_kallsyms,
>  					    false);
> -	if (!dir_name)
> +found:
> +	if (!dir_name) {
> +		pr_debug("Failed to get cache from %s\n", target);
>  		return -ENOMEM;
> +	}
>  
>  	snprintf(cpath, PATH_MAX, "%s/probes", dir_name);
>  	fd = open(cpath, O_CREAT | O_RDWR, 0644);
> @@ -673,3 +683,55 @@ int probe_cache__commit(struct probe_cache *pcache)
>  out:
>  	return ret;
>  }
> +
> +static int probe_cache__show_entries(struct probe_cache *pcache,
> +				     struct strfilter *filter)
> +{
> +	struct probe_cache_entry *entry;
> +	char buf[128], *ptr;
> +
> +	list_for_each_entry(entry, &pcache->entries, node) {
> +		if (entry->pev.event) {
> +			ptr = buf;
> +			snprintf(buf, 128, "%s:%s",
> +				 entry->pev.group, entry->pev.event);
> +		} else
> +			ptr = entry->spev;
> +		if (strfilter__compare(filter, ptr))
> +			printf("%s\n", entry->spev);
> +	}
> +	return 0;
> +}
> +
> +/* Show all cached probes */
> +int probe_cache__show_all_caches(struct strfilter *filter)
> +{
> +	struct probe_cache *pcache;
> +	struct strlist *bidlist;
> +	struct str_node *nd;
> +	char *buf = strfilter__string(filter);
> +
> +	pr_debug("list cache with filter: %s\n", buf);
> +	free(buf);
> +
> +	bidlist = build_id_cache__list_all();
> +	if (!bidlist) {
> +		pr_debug("Failed to get buildids: %d\n", errno);
> +		return -EINVAL;
> +	}
> +	strlist__for_each_entry(nd, bidlist) {
> +		pcache = probe_cache__new(nd->s);
> +		if (!pcache)
> +			continue;
> +		if (!list_empty(&pcache->entries)) {
> +			buf = build_id_cache__origname(nd->s);
> +			printf("%s (%s):\n", buf, nd->s);
> +			free(buf);
> +			probe_cache__show_entries(pcache, filter);
> +		}
> +		probe_cache__delete(pcache);
> +	}
> +	strlist__delete(bidlist);
> +
> +	return 0;
> +}
> diff --git a/tools/perf/util/probe-file.h b/tools/perf/util/probe-file.h
> index 910aa74..0009b8a 100644
> --- a/tools/perf/util/probe-file.h
> +++ b/tools/perf/util/probe-file.h
> @@ -42,4 +42,5 @@ struct probe_cache_entry *probe_cache__find(struct probe_cache *pcache,
>  					    struct perf_probe_event *pev);
>  struct probe_cache_entry *probe_cache__find_by_name(struct probe_cache *pcache,
>  					const char *group, const char *event);
> +int probe_cache__show_all_caches(struct strfilter *filter);
>  #endif

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