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

Arnaldo Carvalho de Melo
2016-07-13T19:36:29Z

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,