Re: [PATCH perf/core 05/10] perf probe: Allow wildcard for cached events

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

Em Tue, Jul 12, 2016 at 07:05:18PM +0900, Masami Hiramatsu escreveu:
> Allo glob wildcard for reusing cached/SDT events. E.g.
> 
>   # perf probe -x /usr/lib64/libc-2.20.so -a %sdt_libc:\*

The example message for this could be improved to also use a wildcard
:-)
 
> This example adds probes for all SDT in libc.
> Note that the SDTs must have been scanned by perf buildid-cache.
> 
> Signed-off-by: Masami Hiramatsu <mhiramat@kernel.org>
> ---
>  Changes in v12:
>   - Rename strlist__for_each to strlist__for_each_entry.
>  Changes in v10:
>   - Split off bugfix, adding interface, and target search patches.
>   - Do not export clear_probe_trace_events().
>  Changes in v7:
>   - Continue to search caches if a build-id cache has no probe cache.
>   - Make probe_cache__open() to accept DSO__NAME_KALLSYMS for kernel.
>   - Fix to add probes correctly when a wildcard matchs both of
>     uprobes and kprobes.
>  Changes in v5.1:
>   - Fix a SEGV bug when a group name is omitted. (Thanks Hemant!)
> ---
>  tools/perf/util/probe-event.c |  107 +++++++++++++++++++++++++++++++++++++++--
>  tools/perf/util/probe-file.c  |   38 ++++++++++++---
>  tools/perf/util/probe-file.h  |    3 +
>  3 files changed, 138 insertions(+), 10 deletions(-)
> 
> diff --git a/tools/perf/util/probe-event.c b/tools/perf/util/probe-event.c
> index 3642cca..1aeac09 100644
> --- a/tools/perf/util/probe-event.c
> +++ b/tools/perf/util/probe-event.c
> @@ -1204,7 +1204,7 @@ static int parse_perf_probe_event_name(char **arg, struct perf_probe_event *pev)
>  	ptr = strchr(*arg, ':');
>  	if (ptr) {
>  		*ptr = '\0';
> -		if (!is_c_func_name(*arg))
> +		if (!pev->sdt && !is_c_func_name(*arg))
>  			goto ng_name;
>  		pev->group = strdup(*arg);
>  		if (!pev->group)
> @@ -1212,7 +1212,7 @@ static int parse_perf_probe_event_name(char **arg, struct perf_probe_event *pev)
>  		*arg = ptr + 1;
>  	} else
>  		pev->group = NULL;
> -	if (!is_c_func_name(*arg)) {
> +	if (!pev->sdt && !is_c_func_name(*arg)) {
>  ng_name:
>  		semantic_error("%s is bad for event name -it must "
>  			       "follow C symbol-naming rule.\n", *arg);
> @@ -1644,6 +1644,7 @@ int parse_probe_trace_command(const char *cmd, struct probe_trace_event *tev)
>  			ret = -ENOMEM;
>  			goto out;
>  		}
> +		tev->uprobes = (tp->module[0] == '/');
>  		p++;
>  	} else
>  		p = argv[1];
> @@ -2518,7 +2519,7 @@ static int probe_trace_event__set_name(struct probe_trace_event *tev,
>  	int ret;
>  
>  	/* If probe_event or trace_event already have the name, reuse it */
> -	if (pev->event)
> +	if (pev->event && !pev->sdt)
>  		event = pev->event;
>  	else if (tev->event)
>  		event = tev->event;
> @@ -2531,7 +2532,7 @@ static int probe_trace_event__set_name(struct probe_trace_event *tev,
>  		else
>  			event = tev->point.realname;
>  	}
> -	if (pev->group)
> +	if (pev->group && !pev->sdt)
>  		group = pev->group;
>  	else if (tev->group)
>  		group = tev->group;
> @@ -2894,6 +2895,100 @@ errout:
>  
>  bool __weak arch__prefers_symtab(void) { return false; }
>  
> +/* Concatinate two arrays */
> +static void *memcat(void *a, size_t sz_a, void *b, size_t sz_b)
> +{
> +	void *ret;
> +
> +	ret = malloc(sz_a + sz_b);
> +	if (ret) {
> +		memcpy(ret, a, sz_a);
> +		memcpy(ret + sz_a, b, sz_b);
> +	}
> +	return ret;
> +}
> +
> +static int
> +concat_probe_trace_events(struct probe_trace_event **tevs, int *ntevs,
> +			  struct probe_trace_event **tevs2, int ntevs2)
> +{
> +	struct probe_trace_event *new_tevs;
> +	int ret = 0;
> +
> +	if (ntevs == 0) {
> +		*tevs = *tevs2;
> +		*ntevs = ntevs2;
> +		*tevs2 = NULL;
> +		return 0;
> +	}
> +
> +	if (*ntevs + ntevs2 > probe_conf.max_probes)
> +		ret = -E2BIG;
> +	else {
> +		/* Concatinate the array of probe_trace_event */
> +		new_tevs = memcat(*tevs, (*ntevs) * sizeof(**tevs),
> +				  *tevs2, ntevs2 * sizeof(**tevs2));
> +		if (!new_tevs)
> +			ret = -ENOMEM;
> +		else {
> +			free(*tevs);
> +			*tevs = new_tevs;
> +			*ntevs += ntevs2;
> +		}
> +	}
> +	if (ret < 0)
> +		clear_probe_trace_events(*tevs2, ntevs2);
> +	zfree(tevs2);
> +
> +	return ret;
> +}
> +
> +/*
> + * Try to find probe_trace_event from given probe caches. Return the number
> + * of cached events found, if an error occurs return the error.
> + */
> +static int find_cached_events(struct perf_probe_event *pev,
> +			      struct probe_trace_event **tevs,
> +			      const char *target)
> +{
> +	struct probe_cache *cache;
> +	struct probe_cache_entry *entry;
> +	struct probe_trace_event *tmp_tevs = NULL;
> +	int ntevs = 0;
> +	int ret = 0;
> +
> +	cache = probe_cache__new(target);
> +	/* Return 0 ("not found") if the target has no probe cache. */
> +	if (!cache)
> +		return 0;
> +
> +	for_each_probe_cache_entry(entry, cache) {
> +		/* Skip the cache entry which has no name */
> +		if (!entry->pev.event || !entry->pev.group)
> +			continue;
> +		if ((!pev->group || strglobmatch(entry->pev.group, pev->group)) &&
> +		    strglobmatch(entry->pev.event, pev->event)) {
> +			ret = probe_cache_entry__get_event(entry, &tmp_tevs);
> +			if (ret > 0)
> +				ret = concat_probe_trace_events(tevs, &ntevs,
> +								&tmp_tevs, ret);
> +			if (ret < 0)
> +				break;
> +		}
> +	}
> +	probe_cache__delete(cache);
> +	if (ret < 0) {
> +		clear_probe_trace_events(*tevs, ntevs);
> +		zfree(tevs);
> +	} else {
> +		ret = ntevs;
> +		if (ntevs > 0 && target && target[0] == '/')
> +			pev->uprobes = true;
> +	}
> +
> +	return ret;
> +}
> +
>  static int find_probe_trace_events_from_cache(struct perf_probe_event *pev,
>  					      struct probe_trace_event **tevs)
>  {
> @@ -2903,6 +2998,10 @@ static int find_probe_trace_events_from_cache(struct perf_probe_event *pev,
>  	struct str_node *node;
>  	int ret, i;
>  
> +	if (pev->sdt)
> +		/* For SDT/cached events, we use special search functions */
> +		return find_cached_events(pev, tevs, pev->target);
> +
>  	cache = probe_cache__new(pev->target);
>  	if (!cache)
>  		return 0;
> diff --git a/tools/perf/util/probe-file.c b/tools/perf/util/probe-file.c
> index 9152ad2..78a84f5 100644
> --- a/tools/perf/util/probe-file.c
> +++ b/tools/perf/util/probe-file.c
> @@ -362,13 +362,38 @@ probe_cache_entry__new(struct perf_probe_event *pev)
>  	return entry;
>  }
>  
> -/* For the kernel probe caches, pass target = NULL */
> +int probe_cache_entry__get_event(struct probe_cache_entry *entry,
> +				 struct probe_trace_event **tevs)
> +{
> +	struct probe_trace_event *tev;
> +	struct str_node *node;
> +	int ret, i;
> +
> +	ret = strlist__nr_entries(entry->tevlist);
> +	if (ret > probe_conf.max_probes)
> +		return -E2BIG;
> +
> +	*tevs = zalloc(ret * sizeof(*tev));
> +	if (!*tevs)
> +		return -ENOMEM;
> +
> +	i = 0;
> +	strlist__for_each_entry(node, entry->tevlist) {
> +		tev = &(*tevs)[i++];
> +		ret = parse_probe_trace_command(node->s, tev);
> +		if (ret < 0)
> +			break;
> +	}
> +	return i;
> +}
> +
> +/* For the kernel probe caches, pass target = NULL or DSO__NAME_KALLSYMS */
>  static int probe_cache__open(struct probe_cache *pcache, const char *target)
>  {
>  	char cpath[PATH_MAX];
>  	char sbuildid[SBUILD_ID_SIZE];
>  	char *dir_name = NULL;
> -	bool is_kallsyms = !target;
> +	bool is_kallsyms = false;
>  	int ret, fd;
>  
>  	if (target && build_id_cache__cached(target)) {
> @@ -378,12 +403,13 @@ static int probe_cache__open(struct probe_cache *pcache, const char *target)
>  		goto found;
>  	}
>  
> -	if (target)
> -		ret = filename__sprintf_build_id(target, sbuildid);
> -	else {
> +	if (!target || !strcmp(target, DSO__NAME_KALLSYMS)) {
>  		target = DSO__NAME_KALLSYMS;
> +		is_kallsyms = true;
>  		ret = sysfs__sprintf_build_id("/", sbuildid);
> -	}
> +	} else
> +		ret = filename__sprintf_build_id(target, sbuildid);
> +
>  	if (ret < 0) {
>  		pr_debug("Failed to get build-id from %s.\n", target);
>  		return ret;
> diff --git a/tools/perf/util/probe-file.h b/tools/perf/util/probe-file.h
> index d513b34..cafbe1d 100644
> --- a/tools/perf/util/probe-file.h
> +++ b/tools/perf/util/probe-file.h
> @@ -34,6 +34,9 @@ int probe_file__get_events(int fd, struct strfilter *filter,
>  				  struct strlist *plist);
>  int probe_file__del_strlist(int fd, struct strlist *namelist);
>  
> +int probe_cache_entry__get_event(struct probe_cache_entry *entry,
> +				 struct probe_trace_event **tevs);
> +
>  struct probe_cache *probe_cache__new(const char *target);
>  int probe_cache__add_entry(struct probe_cache *pcache,
>  			   struct perf_probe_event *pev,