perf probe: Allow wildcard for cached events

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.

Committer note:

Using it to check what of those SDT probes would take place when doing
a cargo run (rust):

  # trace --no-sys --event sdt_libc:* cargo run
     0.000 sdt_libc:setjmp:(7f326b69c4d1))
    28.423 sdt_libc:setjmp:(7f4b0a5364d1))
    29.000 sdt_libc:setjmp:(7f4b0a5364d1))
    88.597 sdt_libc:setjmp:(7fc01fd414d1))
    89.220 sdt_libc:setjmp:(7fc01fd414d1))
    95.501 sdt_libc:setjmp:(7f326b69c4d1))
     Running `target/debug/hello_world`
    97.110 sdt_libc:setjmp:(7f95e09234d1))
  Hello, world!
  #

Signed-off-by: Masami Hiramatsu <mhiramat@kernel.org>
Tested-by: Arnaldo Carvalho de Melo <acme@redhat.com>
Cc: Ananth N Mavinakayanahalli <ananth@linux.vnet.ibm.com>
Cc: Brendan Gregg <brendan.d.gregg@gmail.com>
Cc: Hemant Kumar <hemant@linux.vnet.ibm.com>
Cc: Namhyung Kim <namhyung@kernel.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Link: http://lkml.kernel.org/r/146831791813.17065.17846564230840594888.stgit@devbox
Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>

3 files changed, 138 insertions, 10 deletions

diff --git a/tools/perf/util/probe-event.c b/tools/perf/util/probe-event.c
index 85f25d41cf8d..7b96e687568e 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 abfb05cf135b..9aed9c332da6 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 d513b346a70e..cafbe1d3f3bf 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,