perf buildid-cache: Scan and import user SDT events to probe cache

perf buildid-cache --add <binary> scans given binary and add
the SDT events to probe cache. "sdt_" prefix is appended for
all SDT providers to avoid event-name clash with other pre-defined
events. It is possible to use the cached SDT events as other cached
events, via perf probe --add "sdt_<provider>:<event>=<event>".

e.g.
  ----
  # perf buildid-cache --add /lib/libc-2.17.so
  # perf probe --cache --list | head -n 5
  /usr/lib/libc-2.17.so (a6fb821bdf53660eb2c29f778757aef294d3d392):
  sdt_libc:setjmp=setjmp
  sdt_libc:longjmp=longjmp
  sdt_libc:longjmp_target=longjmp_target
  sdt_libc:memory_heap_new=memory_heap_new
  # perf probe -x /usr/lib/libc-2.17.so \
    -a sdt_libc:memory_heap_new=memory_heap_new
  Added new event:
    sdt_libc:memory_heap_new (on memory_heap_new
   in /usr/lib/libc-2.17.so)

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

          perf record -e sdt_libc:memory_heap_new -aR sleep 1

  # perf probe -l
    sdt_libc:memory_heap_new (on new_heap+183 in /usr/lib/libc-2.17.so)
  ----

Note that SDT event entries in probe-cache file is somewhat different
from normal cached events. Normal one starts with "#", but SDTs are
starting with "%".

Signed-off-by: Masami Hiramatsu <mhiramat@kernel.org>
Signed-off-by: Masami Hiramatsu <masami.hiramatsu.pt@hitachi.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/146736025058.27797.13043265488541434502.stgit@devbox
Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>

4 files changed, 101 insertions, 3 deletions

diff --git a/tools/perf/Documentation/perf-buildid-cache.txt b/tools/perf/Documentation/perf-buildid-cache.txt
index dd07b55f58d8..058064db39d2 100644
--- a/tools/perf/Documentation/perf-buildid-cache.txt
+++ b/tools/perf/Documentation/perf-buildid-cache.txt
@@ -15,6 +15,9 @@ DESCRIPTION
 This command manages the build-id cache. It can add, remove, update and purge
 files to/from the cache. In the future it should as well set upper limits for
 the space used by the cache, etc.
+This also scans the target binary for SDT (Statically Defined Tracing) and
+record it along with the buildid-cache, which will be used by perf-probe.
+For more details, see linkperf:perf-probe[1].
 
 OPTIONS
 -------
diff --git a/tools/perf/util/build-id.c b/tools/perf/util/build-id.c
index 1c49620e98b2..e1a16408da9c 100644
--- a/tools/perf/util/build-id.c
+++ b/tools/perf/util/build-id.c
@@ -17,6 +17,7 @@
 #include "tool.h"
 #include "header.h"
 #include "vdso.h"
+#include "probe-file.h"
 
 
 static bool no_buildid_cache;
@@ -532,6 +533,30 @@ int build_id_cache__list_build_ids(const char *pathname,
         return ret;
 }
 
+#ifdef HAVE_LIBELF_SUPPORT
+static int build_id_cache__add_sdt_cache(const char *sbuild_id,
+                                          const char *realname)
+{
+        struct probe_cache *cache;
+        int ret;
+
+        cache = probe_cache__new(sbuild_id);
+        if (!cache)
+                return -1;
+
+        ret = probe_cache__scan_sdt(cache, realname);
+        if (ret >= 0) {
+                pr_debug("Found %d SDTs in %s\n", ret, realname);
+                if (probe_cache__commit(cache) < 0)
+                        ret = -1;
+        }
+        probe_cache__delete(cache);
+        return ret;
+}
+#else
+#define build_id_cache__add_sdt_cache(sbuild_id, realname) (0)
+#endif
+
 int build_id_cache__add_s(const char *sbuild_id, const char *name,
                           bool is_kallsyms, bool is_vdso)
 {
@@ -589,6 +614,11 @@ int build_id_cache__add_s(const char *sbuild_id, const char *name,
 
         if (symlink(tmp, linkname) == 0)
                 err = 0;
+
+        /* Update SDT cache : error is just warned */
+        if (build_id_cache__add_sdt_cache(sbuild_id, realname) < 0)
+                pr_debug("Failed to update/scan SDT cache for %s\n", realname);
+
 out_free:
         if (!is_kallsyms)
                 free(realname);
diff --git a/tools/perf/util/probe-file.c b/tools/perf/util/probe-file.c
index 6cb6ec03c1fe..5b563b2e8b1d 100644
--- a/tools/perf/util/probe-file.c
+++ b/tools/perf/util/probe-file.c
@@ -434,12 +434,15 @@ static int probe_cache__load(struct probe_cache *pcache)
                 p = strchr(buf, '\n');
                 if (p)
                         *p = '\0';
-                if (buf[0] == '#') {    /* #perf_probe_event */
+                /* #perf_probe_event or %sdt_event */
+                if (buf[0] == '#' || buf[0] == '%') {
                         entry = probe_cache_entry__new(NULL);
                         if (!entry) {
                                 ret = -ENOMEM;
                                 goto out;
                         }
+                        if (buf[0] == '%')
+                                entry->sdt = true;
                         entry->spev = strdup(buf + 1);
                         if (entry->spev)
                                 ret = parse_perf_probe_command(buf + 1,
@@ -621,19 +624,79 @@ out_err:
         return ret;
 }
 
+static unsigned long long sdt_note__get_addr(struct sdt_note *note)
+{
+        return note->bit32 ? (unsigned long long)note->addr.a32[0]
+                 : (unsigned long long)note->addr.a64[0];
+}
+
+int probe_cache__scan_sdt(struct probe_cache *pcache, const char *pathname)
+{
+        struct probe_cache_entry *entry = NULL;
+        struct list_head sdtlist;
+        struct sdt_note *note;
+        char *buf;
+        char sdtgrp[64];
+        int ret;
+
+        INIT_LIST_HEAD(&sdtlist);
+        ret = get_sdt_note_list(&sdtlist, pathname);
+        if (ret < 0) {
+                pr_debug("Failed to get sdt note: %d\n", ret);
+                return ret;
+        }
+        list_for_each_entry(note, &sdtlist, note_list) {
+                ret = snprintf(sdtgrp, 64, "sdt_%s", note->provider);
+                if (ret < 0)
+                        break;
+                /* Try to find same-name entry */
+                entry = probe_cache__find_by_name(pcache, sdtgrp, note->name);
+                if (!entry) {
+                        entry = probe_cache_entry__new(NULL);
+                        if (!entry) {
+                                ret = -ENOMEM;
+                                break;
+                        }
+                        entry->sdt = true;
+                        ret = asprintf(&entry->spev, "%s:%s=%s", sdtgrp,
+                                        note->name, note->name);
+                        if (ret < 0)
+                                break;
+                        entry->pev.event = strdup(note->name);
+                        entry->pev.group = strdup(sdtgrp);
+                        list_add_tail(&entry->node, &pcache->entries);
+                }
+                ret = asprintf(&buf, "p:%s/%s %s:0x%llx",
+                                sdtgrp, note->name, pathname,
+                                sdt_note__get_addr(note));
+                if (ret < 0)
+                        break;
+                strlist__add(entry->tevlist, buf);
+                free(buf);
+                entry = NULL;
+        }
+        if (entry) {
+                list_del_init(&entry->node);
+                probe_cache_entry__delete(entry);
+        }
+        cleanup_sdt_note_list(&sdtlist);
+        return ret;
+}
+
 static int probe_cache_entry__write(struct probe_cache_entry *entry, int fd)
 {
         struct str_node *snode;
         struct stat st;
         struct iovec iov[3];
+        const char *prefix = entry->sdt ? "%" : "#";
         int ret;
         /* Save stat for rollback */
         ret = fstat(fd, &st);
         if (ret < 0)
                 return ret;
 
-        pr_debug("Writing cache: #%s\n", entry->spev);
-        iov[0].iov_base = (void *)"#"; iov[0].iov_len = 1;
+        pr_debug("Writing cache: %s%s\n", prefix, entry->spev);
+        iov[0].iov_base = (void *)prefix; iov[0].iov_len = 1;
         iov[1].iov_base = entry->spev; iov[1].iov_len = strlen(entry->spev);
         iov[2].iov_base = (void *)"\n"; iov[2].iov_len = 1;
         ret = writev(fd, iov, 3);
diff --git a/tools/perf/util/probe-file.h b/tools/perf/util/probe-file.h
index 0ed1fc563b77..ddf5ae212c2f 100644
--- a/tools/perf/util/probe-file.h
+++ b/tools/perf/util/probe-file.h
@@ -8,6 +8,7 @@
 /* Cache of probe definitions */
 struct probe_cache_entry {
         struct list_head        node;
+        bool                    sdt;
         struct perf_probe_event pev;
         char                    *spev;
         struct strlist          *tevlist;
@@ -35,6 +36,7 @@ struct probe_cache *probe_cache__new(const char *target);
 int probe_cache__add_entry(struct probe_cache *pcache,
                            struct perf_probe_event *pev,
                            struct probe_trace_event *tevs, int ntevs);
+int probe_cache__scan_sdt(struct probe_cache *pcache, const char *pathname);
 int probe_cache__commit(struct probe_cache *pcache);
 void probe_cache__purge(struct probe_cache *pcache);
 void probe_cache__delete(struct probe_cache *pcache);