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Subject[tip:perf/core] perf probe: Introduce perf_cache interfaces
Commit-ID:  dd975497adcdd2526ae332d3938bd5d6e1c3731a
Gitweb: http://git.kernel.org/tip/dd975497adcdd2526ae332d3938bd5d6e1c3731a
Author: Masami Hiramatsu <mhiramat@kernel.org>
AuthorDate: Wed, 15 Jun 2016 12:28:30 +0900
Committer: Arnaldo Carvalho de Melo <acme@redhat.com>
CommitDate: Wed, 15 Jun 2016 14:34:31 -0300

perf probe: Introduce perf_cache interfaces

Introduce perf_cache object and interfaces to create, add entries,
commit, and delete the object.

perf_cache represents a file for the cached "perf probe" definitions on
one binary file or vmlinux which has its own build id. The probe cache
file is located under the build-id cache directory of the target binary,
as below;

<perf-debug-dir>/.build-id/<BU>/<ILDID>/probe

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/20160615032830.31330.84998.stgit@devbox
Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>
---
tools/perf/util/probe-file.c | 331 +++++++++++++++++++++++++++++++++++++++++++
tools/perf/util/probe-file.h | 20 +++
2 files changed, 351 insertions(+)

diff --git a/tools/perf/util/probe-file.c b/tools/perf/util/probe-file.c
index 3fe6214..25a4042 100644
--- a/tools/perf/util/probe-file.c
+++ b/tools/perf/util/probe-file.c
@@ -14,6 +14,7 @@
* GNU General Public License for more details.
*
*/
+#include <sys/uio.h>
#include "util.h"
#include "event.h"
#include "strlist.h"
@@ -324,3 +325,333 @@ int probe_file__del_events(int fd, struct strfilter *filter)

return ret;
}
+
+/* Caller must ensure to remove this entry from list */
+static void probe_cache_entry__delete(struct probe_cache_entry *entry)
+{
+ if (entry) {
+ BUG_ON(!list_empty(&entry->node));
+
+ strlist__delete(entry->tevlist);
+ clear_perf_probe_event(&entry->pev);
+ zfree(&entry->spev);
+ free(entry);
+ }
+}
+
+static struct probe_cache_entry *
+probe_cache_entry__new(struct perf_probe_event *pev)
+{
+ struct probe_cache_entry *entry = zalloc(sizeof(*entry));
+
+ if (entry) {
+ INIT_LIST_HEAD(&entry->node);
+ entry->tevlist = strlist__new(NULL, NULL);
+ if (!entry->tevlist)
+ zfree(&entry);
+ else if (pev) {
+ entry->spev = synthesize_perf_probe_command(pev);
+ if (!entry->spev ||
+ perf_probe_event__copy(&entry->pev, pev) < 0) {
+ probe_cache_entry__delete(entry);
+ return NULL;
+ }
+ }
+ }
+
+ return entry;
+}
+
+/* For the kernel probe caches, pass target = NULL */
+static int probe_cache__open(struct probe_cache *pcache, const char *target)
+{
+ char cpath[PATH_MAX];
+ char sbuildid[SBUILD_ID_SIZE];
+ char *dir_name;
+ bool is_kallsyms = !target;
+ int ret, fd;
+
+ if (target)
+ ret = filename__sprintf_build_id(target, sbuildid);
+ else {
+ target = DSO__NAME_KALLSYMS;
+ ret = sysfs__sprintf_build_id("/", sbuildid);
+ }
+ if (ret < 0) {
+ pr_debug("Failed to get build-id from %s.\n", target);
+ return ret;
+ }
+
+ /* If we have no buildid cache, make it */
+ if (!build_id_cache__cached(sbuildid)) {
+ ret = build_id_cache__add_s(sbuildid, target,
+ is_kallsyms, NULL);
+ if (ret < 0) {
+ pr_debug("Failed to add build-id cache: %s\n", target);
+ return ret;
+ }
+ }
+
+ dir_name = build_id_cache__cachedir(sbuildid, target, is_kallsyms,
+ false);
+ if (!dir_name)
+ return -ENOMEM;
+
+ snprintf(cpath, PATH_MAX, "%s/probes", dir_name);
+ fd = open(cpath, O_CREAT | O_RDWR, 0644);
+ if (fd < 0)
+ pr_debug("Failed to open cache(%d): %s\n", fd, cpath);
+ free(dir_name);
+ pcache->fd = fd;
+
+ return fd;
+}
+
+static int probe_cache__load(struct probe_cache *pcache)
+{
+ struct probe_cache_entry *entry = NULL;
+ char buf[MAX_CMDLEN], *p;
+ int ret = 0;
+ FILE *fp;
+
+ fp = fdopen(dup(pcache->fd), "r");
+ if (!fp)
+ return -EINVAL;
+
+ while (!feof(fp)) {
+ if (!fgets(buf, MAX_CMDLEN, fp))
+ break;
+ p = strchr(buf, '\n');
+ if (p)
+ *p = '\0';
+ if (buf[0] == '#') { /* #perf_probe_event */
+ entry = probe_cache_entry__new(NULL);
+ if (!entry) {
+ ret = -ENOMEM;
+ goto out;
+ }
+ entry->spev = strdup(buf + 1);
+ if (entry->spev)
+ ret = parse_perf_probe_command(buf + 1,
+ &entry->pev);
+ else
+ ret = -ENOMEM;
+ if (ret < 0) {
+ probe_cache_entry__delete(entry);
+ goto out;
+ }
+ list_add_tail(&entry->node, &pcache->entries);
+ } else { /* trace_probe_event */
+ if (!entry) {
+ ret = -EINVAL;
+ goto out;
+ }
+ strlist__add(entry->tevlist, buf);
+ }
+ }
+out:
+ fclose(fp);
+ return ret;
+}
+
+static struct probe_cache *probe_cache__alloc(void)
+{
+ struct probe_cache *pcache = zalloc(sizeof(*pcache));
+
+ if (pcache) {
+ INIT_LIST_HEAD(&pcache->entries);
+ pcache->fd = -EINVAL;
+ }
+ return pcache;
+}
+
+void probe_cache__purge(struct probe_cache *pcache)
+{
+ struct probe_cache_entry *entry, *n;
+
+ list_for_each_entry_safe(entry, n, &pcache->entries, node) {
+ list_del_init(&entry->node);
+ probe_cache_entry__delete(entry);
+ }
+}
+
+void probe_cache__delete(struct probe_cache *pcache)
+{
+ if (!pcache)
+ return;
+
+ probe_cache__purge(pcache);
+ if (pcache->fd > 0)
+ close(pcache->fd);
+ free(pcache);
+}
+
+struct probe_cache *probe_cache__new(const char *target)
+{
+ struct probe_cache *pcache = probe_cache__alloc();
+ int ret;
+
+ if (!pcache)
+ return NULL;
+
+ ret = probe_cache__open(pcache, target);
+ if (ret < 0) {
+ pr_debug("Cache open error: %d\n", ret);
+ goto out_err;
+ }
+
+ ret = probe_cache__load(pcache);
+ if (ret < 0) {
+ pr_debug("Cache read error: %d\n", ret);
+ goto out_err;
+ }
+
+ return pcache;
+
+out_err:
+ probe_cache__delete(pcache);
+ return NULL;
+}
+
+static bool streql(const char *a, const char *b)
+{
+ if (a == b)
+ return true;
+
+ if (!a || !b)
+ return false;
+
+ return !strcmp(a, b);
+}
+
+static struct probe_cache_entry *
+probe_cache__find(struct probe_cache *pcache, struct perf_probe_event *pev)
+{
+ struct probe_cache_entry *entry = NULL;
+ char *cmd = synthesize_perf_probe_command(pev);
+
+ if (!cmd)
+ return NULL;
+
+ list_for_each_entry(entry, &pcache->entries, node) {
+ /* Hit if same event name or same command-string */
+ if ((pev->event &&
+ (streql(entry->pev.group, pev->group) &&
+ streql(entry->pev.event, pev->event))) ||
+ (!strcmp(entry->spev, cmd)))
+ goto found;
+ }
+ entry = NULL;
+
+found:
+ free(cmd);
+ return entry;
+}
+
+int probe_cache__add_entry(struct probe_cache *pcache,
+ struct perf_probe_event *pev,
+ struct probe_trace_event *tevs, int ntevs)
+{
+ struct probe_cache_entry *entry = NULL;
+ char *command;
+ int i, ret = 0;
+
+ if (!pcache || !pev || !tevs || ntevs <= 0) {
+ ret = -EINVAL;
+ goto out_err;
+ }
+
+ /* Remove old cache entry */
+ entry = probe_cache__find(pcache, pev);
+ if (entry) {
+ list_del_init(&entry->node);
+ probe_cache_entry__delete(entry);
+ }
+
+ ret = -ENOMEM;
+ entry = probe_cache_entry__new(pev);
+ if (!entry)
+ goto out_err;
+
+ for (i = 0; i < ntevs; i++) {
+ if (!tevs[i].point.symbol)
+ continue;
+
+ command = synthesize_probe_trace_command(&tevs[i]);
+ if (!command)
+ goto out_err;
+ strlist__add(entry->tevlist, command);
+ free(command);
+ }
+ list_add_tail(&entry->node, &pcache->entries);
+ pr_debug("Added probe cache: %d\n", ntevs);
+ return 0;
+
+out_err:
+ pr_debug("Failed to add probe caches\n");
+ probe_cache_entry__delete(entry);
+ 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];
+ 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;
+ 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);
+ if (ret < (int)iov[1].iov_len + 2)
+ goto rollback;
+
+ strlist__for_each(snode, entry->tevlist) {
+ iov[0].iov_base = (void *)snode->s;
+ iov[0].iov_len = strlen(snode->s);
+ iov[1].iov_base = (void *)"\n"; iov[1].iov_len = 1;
+ ret = writev(fd, iov, 2);
+ if (ret < (int)iov[0].iov_len + 1)
+ goto rollback;
+ }
+ return 0;
+
+rollback:
+ /* Rollback to avoid cache file corruption */
+ if (ret > 0)
+ ret = -1;
+ if (ftruncate(fd, st.st_size) < 0)
+ ret = -2;
+
+ return ret;
+}
+
+int probe_cache__commit(struct probe_cache *pcache)
+{
+ struct probe_cache_entry *entry;
+ int ret = 0;
+
+ /* TBD: if we do not update existing entries, skip it */
+ ret = lseek(pcache->fd, 0, SEEK_SET);
+ if (ret < 0)
+ goto out;
+
+ ret = ftruncate(pcache->fd, 0);
+ if (ret < 0)
+ goto out;
+
+ list_for_each_entry(entry, &pcache->entries, node) {
+ ret = probe_cache_entry__write(entry, pcache->fd);
+ pr_debug("Cache committed: %d\n", ret);
+ if (ret < 0)
+ break;
+ }
+out:
+ return ret;
+}
diff --git a/tools/perf/util/probe-file.h b/tools/perf/util/probe-file.h
index 18ac9cf..d872e3d 100644
--- a/tools/perf/util/probe-file.h
+++ b/tools/perf/util/probe-file.h
@@ -5,6 +5,19 @@
#include "strfilter.h"
#include "probe-event.h"

+/* Cache of probe definitions */
+struct probe_cache_entry {
+ struct list_head node;
+ struct perf_probe_event pev;
+ char *spev;
+ struct strlist *tevlist;
+};
+
+struct probe_cache {
+ int fd;
+ struct list_head entries;
+};
+
#define PF_FL_UPROBE 1
#define PF_FL_RW 2

@@ -18,5 +31,12 @@ int probe_file__get_events(int fd, struct strfilter *filter,
struct strlist *plist);
int probe_file__del_strlist(int fd, struct strlist *namelist);

+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__commit(struct probe_cache *pcache);
+void probe_cache__purge(struct probe_cache *pcache);
+void probe_cache__delete(struct probe_cache *pcache);

#endif
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