perf: Add pipe-specific header read/write and event processing code

This patch makes several changes to allow the perf event stream
to be sent and received over a pipe:

- adds pipe-specific versions of the header read/write code

- adds pipe-specific version of the event processing code

- adds a range of event types to be used for header or other
  pseudo events, above the range used by the kernel

- checks the return value of event handlers, which they can use
  to skip over large events during event processing rather than actually
  reading them into event objects.

- unifies the multiple do_read() functions and updates its
  users.

Note that none of these changes affect the existing perf data
file format or processing - this code only comes into play if
perf output is sent to stdout (or is read from stdin).

Signed-off-by: Tom Zanussi <tzanussi@gmail.com>
Acked-by: Thomas Gleixner <tglx@linutronix.de>
Cc: fweisbec@gmail.com
Cc: rostedt@goodmis.org
Cc: k-keiichi@bx.jp.nec.com
Cc: acme@ghostprotocols.net
LKML-Reference: <1270184365-8281-2-git-send-email-tzanussi@gmail.com>
Signed-off-by: Ingo Molnar <mingo@elte.hu>

1 files changed, 126 insertions, 9 deletions

diff --git a/tools/perf/util/session.c b/tools/perf/util/session.c
index ddf288fca3eb..2c1277cb4ae4 100644
--- a/tools/perf/util/session.c
+++ b/tools/perf/util/session.c
@@ -14,6 +14,16 @@ static int perf_session__open(struct perf_session *self, bool force)
 {
         struct stat input_stat;
 
+        if (!strcmp(self->filename, "-")) {
+                self->fd_pipe = true;
+                self->fd = STDIN_FILENO;
+
+                if (perf_header__read(self, self->fd) < 0)
+                        pr_err("incompatible file format");
+
+                return 0;
+        }
+
         self->fd = open(self->filename, O_RDONLY);
         if (self->fd < 0) {
                 pr_err("failed to open file: %s", self->filename);
@@ -38,7 +48,7 @@ static int perf_session__open(struct perf_session *self, bool force)
                 goto out_close;
         }
 
-        if (perf_header__read(&self->header, self->fd) < 0) {
+        if (perf_header__read(self, self->fd) < 0) {
                 pr_err("incompatible file format");
                 goto out_close;
         }
@@ -52,6 +62,11 @@ out_close:
         return -1;
 }
 
+void perf_session__update_sample_type(struct perf_session *self)
+{
+        self->sample_type = perf_header__sample_type(&self->header);
+}
+
 struct perf_session *perf_session__new(const char *filename, int mode, bool force)
 {
         size_t len = filename ? strlen(filename) + 1 : 0;
@@ -85,7 +100,7 @@ struct perf_session *perf_session__new(const char *filename, int mode, bool forc
                         goto out_delete;
         }
 
-        self->sample_type = perf_header__sample_type(&self->header);
+        perf_session__update_sample_type(self);
 out:
         return self;
 out_free:
@@ -200,14 +215,17 @@ static const char *event__name[] = {
         [PERF_RECORD_SAMPLE]     = "SAMPLE",
 };
 
-unsigned long event__total[PERF_RECORD_MAX];
+unsigned long event__total[PERF_RECORD_HEADER_MAX];
 
 void event__print_totals(void)
 {
         int i;
-        for (i = 0; i < PERF_RECORD_MAX; ++i)
+        for (i = 0; i < PERF_RECORD_HEADER_MAX; ++i) {
+                if (!event__name[i])
+                        continue;
                 pr_info("%10s events: %10ld\n",
                         event__name[i], event__total[i]);
+        }
 }
 
 void mem_bswap_64(void *src, int byte_size)
@@ -271,7 +289,7 @@ static event__swap_op event__swap_ops[] = {
         [PERF_RECORD_LOST]   = event__all64_swap,
         [PERF_RECORD_READ]   = event__read_swap,
         [PERF_RECORD_SAMPLE] = event__all64_swap,
-        [PERF_RECORD_MAX]    = NULL,
+        [PERF_RECORD_HEADER_MAX]    = NULL,
 };
 
 static int perf_session__process_event(struct perf_session *self,
@@ -281,7 +299,7 @@ static int perf_session__process_event(struct perf_session *self,
 {
         trace_event(event);
 
-        if (event->header.type < PERF_RECORD_MAX) {
+        if (event->header.type < PERF_RECORD_HEADER_MAX) {
                 dump_printf("%#Lx [%#x]: PERF_RECORD_%s",
                             offset + head, event->header.size,
                             event__name[event->header.type]);
@@ -376,6 +394,101 @@ static struct thread *perf_session__register_idle_thread(struct perf_session *se
         return thread;
 }
 
+int do_read(int fd, void *buf, size_t size)
+{
+        void *buf_start = buf;
+
+        while (size) {
+                int ret = read(fd, buf, size);
+
+                if (ret <= 0)
+                        return ret;
+
+                size -= ret;
+                buf += ret;
+        }
+
+        return buf - buf_start;
+}
+
+#define session_done()  (*(volatile int *)(&session_done))
+volatile int session_done;
+
+static int __perf_session__process_pipe_events(struct perf_session *self,
+                                               struct perf_event_ops *ops)
+{
+        event_t event;
+        uint32_t size;
+        int skip = 0;
+        u64 head;
+        int err;
+        void *p;
+
+        perf_event_ops__fill_defaults(ops);
+
+        head = 0;
+more:
+        err = do_read(self->fd, &event, sizeof(struct perf_event_header));
+        if (err <= 0) {
+                if (err == 0)
+                        goto done;
+
+                pr_err("failed to read event header\n");
+                goto out_err;
+        }
+
+        if (self->header.needs_swap)
+                perf_event_header__bswap(&event.header);
+
+        size = event.header.size;
+        if (size == 0)
+                size = 8;
+
+        p = &event;
+        p += sizeof(struct perf_event_header);
+
+        err = do_read(self->fd, p, size - sizeof(struct perf_event_header));
+        if (err <= 0) {
+                if (err == 0) {
+                        pr_err("unexpected end of event stream\n");
+                        goto done;
+                }
+
+                pr_err("failed to read event data\n");
+                goto out_err;
+        }
+
+        if (size == 0 ||
+            (skip = perf_session__process_event(self, &event, ops,
+                                                0, head)) < 0) {
+                dump_printf("%#Lx [%#x]: skipping unknown header type: %d\n",
+                            head, event.header.size, event.header.type);
+                /*
+                 * assume we lost track of the stream, check alignment, and
+                 * increment a single u64 in the hope to catch on again 'soon'.
+                 */
+                if (unlikely(head & 7))
+                        head &= ~7ULL;
+
+                size = 8;
+        }
+
+        head += size;
+
+        dump_printf("\n%#Lx [%#x]: event: %d\n",
+                    head, event.header.size, event.header.type);
+
+        if (skip > 0)
+                head += skip;
+
+        if (!session_done())
+                goto more;
+done:
+        err = 0;
+out_err:
+        return err;
+}
+
 int __perf_session__process_events(struct perf_session *self,
                                    u64 data_offset, u64 data_size,
                                    u64 file_size, struct perf_event_ops *ops)
@@ -499,9 +612,13 @@ out_getcwd_err:
                 self->cwdlen = strlen(self->cwd);
         }
 
-        err = __perf_session__process_events(self, self->header.data_offset,
-                                             self->header.data_size,
-                                             self->size, ops);
+        if (!self->fd_pipe)
+                err = __perf_session__process_events(self,
+                                                     self->header.data_offset,
+                                                     self->header.data_size,
+                                                     self->size, ops);
+        else
+                err = __perf_session__process_pipe_events(self, ops);
 out_err:
         return err;
 }