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

Masami Hiramatsu
2016-07-12T10:05:29Z

Allo glob wildcard for reusing cached/SDT events. E.g.

# perf probe -x /usr/lib64/libc-2.20.so -a %sdt_libc:\*

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,