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Subject[RFC PATCH 2/7] perf: add pipe-specific header read/write and event processing code
Date
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

- adds code to interpret return values >0 from event processing
functions as 'actions'. The first action defined is for stopping
the event-processing loop at the first non-header event. So
initially there's still a restriction that header events come first
in the event stream.

Note that none of this affects 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>
---
tools/perf/builtin-record.c | 8 ++-
tools/perf/builtin-report.c | 10 +++
tools/perf/builtin-trace.c | 11 +++
tools/perf/util/event.h | 4 +
tools/perf/util/header.c | 62 ++++++++++++++++++-
tools/perf/util/header.h | 8 ++-
tools/perf/util/session.c | 145 +++++++++++++++++++++++++++++++++++++++---
tools/perf/util/session.h | 16 +++++
8 files changed, 249 insertions(+), 15 deletions(-)
diff --git a/tools/perf/builtin-record.c b/tools/perf/builtin-record.c
index 4fe87e3..b676689 100644
--- a/tools/perf/builtin-record.c
+++ b/tools/perf/builtin-record.c
@@ -475,7 +475,7 @@ static int __cmd_record(int argc, const char **argv)
}

if (!file_new) {
- err = perf_header__read(&session->header, output);
+ err = perf_header__read(session, output);
if (err < 0)
return err;
}
@@ -554,7 +554,11 @@ static int __cmd_record(int argc, const char **argv)
open_counters(i, target_pid);
}

- if (file_new) {
+ if (pipe_output) {
+ err = perf_header__write_pipe(&session->header, output);
+ if (err < 0)
+ return err;
+ } else if (file_new) {
err = perf_header__write(&session->header, output, false);
if (err < 0)
return err;
diff --git a/tools/perf/builtin-report.c b/tools/perf/builtin-report.c
index ca12efa..603f705 100644
--- a/tools/perf/builtin-report.c
+++ b/tools/perf/builtin-report.c
@@ -193,11 +193,21 @@ static struct perf_event_ops event_ops = {
.read = process_read_event,
};

+extern volatile int done;
+
+static void sig_handler(int sig __attribute__((__unused__)))
+{
+ done = 1;
+}
+
static int __cmd_report(void)
{
int ret = -EINVAL;
struct perf_session *session;

+ signal(SIGCHLD, sig_handler);
+ signal(SIGINT, sig_handler);
+
session = perf_session__new(input_name, O_RDONLY, force);
if (session == NULL)
return -ENOMEM;
diff --git a/tools/perf/builtin-trace.c b/tools/perf/builtin-trace.c
index 407041d..2a56dda 100644
--- a/tools/perf/builtin-trace.c
+++ b/tools/perf/builtin-trace.c
@@ -106,8 +106,18 @@ static struct perf_event_ops event_ops = {
.comm = event__process_comm,
};

+extern volatile int done;
+
+static void sig_handler(int sig __unused)
+{
+ done = 1;
+}
+
static int __cmd_trace(struct perf_session *session)
{
+ signal(SIGCHLD, sig_handler);
+ signal(SIGINT, sig_handler);
+
return perf_session__process_events(session, &event_ops);
}

@@ -609,6 +619,7 @@ int cmd_trace(int argc, const char **argv, const char *prefix __used)
return -1;
}

+ perf_header__read(session, input);
err = scripting_ops->generate_script("perf-trace");
goto out;
}
diff --git a/tools/perf/util/event.h b/tools/perf/util/event.h
index 50a7132..cec3067 100644
--- a/tools/perf/util/event.h
+++ b/tools/perf/util/event.h
@@ -83,6 +83,10 @@ struct build_id_event {
char filename[];
};

+enum perf_header_event_type { /* above any possible kernel type */
+ PERF_RECORD_HEADER_MAX = 64,
+};
+
typedef union event_union {
struct perf_event_header header;
struct ip_event ip;
diff --git a/tools/perf/util/header.c b/tools/perf/util/header.c
index 6c9aa16..75b8a4c 100644
--- a/tools/perf/util/header.c
+++ b/tools/perf/util/header.c
@@ -427,6 +427,26 @@ out_free:
return err;
}

+int perf_header__write_pipe(struct perf_header *self, int fd)
+{
+ struct perf_file_header_pipe f_header;
+ int err;
+
+ f_header = (struct perf_file_header_pipe){
+ .magic = PERF_MAGIC,
+ .size = sizeof(f_header),
+ };
+
+ err = do_write(fd, &f_header, sizeof(f_header));
+ if (err < 0) {
+ pr_debug("failed to write perf pipe header\n");
+ return err;
+ }
+
+ self->frozen = 1;
+ return 0;
+}
+
int perf_header__write(struct perf_header *self, int fd, bool at_exit)
{
struct perf_file_header f_header;
@@ -662,13 +682,53 @@ static int perf_file_section__process(struct perf_file_section *self,
return 0;
}

-int perf_header__read(struct perf_header *self, int fd)
+static int perf_file_header__read_pipe(struct perf_file_header_pipe *self,
+ struct perf_header *ph, int fd)
+{
+ if (do_read(fd, self, sizeof(*self)) ||
+ memcmp(&self->magic, __perf_magic, sizeof(self->magic)))
+ return -1;
+
+ if (self->size != sizeof(*self)) {
+ u64 size = bswap_64(self->size);
+
+ if (size != sizeof(*self))
+ return -1;
+
+ ph->needs_swap = true;
+ }
+
+ return 0;
+}
+
+static int perf_header__read_pipe(struct perf_session *session, int fd)
{
+ struct perf_header *self = &session->header;
+ struct perf_file_header_pipe f_header;
+ struct perf_event_ops header_ops;
+
+ if (perf_file_header__read_pipe(&f_header, self, fd) < 0) {
+ pr_debug("incompatible file format\n");
+ return -EINVAL;
+ }
+
+ perf_event_ops__fill_stop(&header_ops);
+ session->fd = fd;
+
+ return perf_session__process_events(session, &header_ops);
+}
+
+int perf_header__read(struct perf_session *session, int fd)
+{
+ struct perf_header *self = &session->header;
struct perf_file_header f_header;
struct perf_file_attr f_attr;
u64 f_id;
int nr_attrs, nr_ids, i, j;

+ if (session->fd_pipe)
+ return perf_header__read_pipe(session, fd);
+
if (perf_file_header__read(&f_header, self, fd) < 0) {
pr_debug("incompatible file format\n");
return -EINVAL;
diff --git a/tools/perf/util/header.h b/tools/perf/util/header.h
index 82a6af7..714b1d5 100644
--- a/tools/perf/util/header.h
+++ b/tools/perf/util/header.h
@@ -39,6 +39,11 @@ struct perf_file_header {
DECLARE_BITMAP(adds_features, HEADER_FEAT_BITS);
};

+struct perf_file_header_pipe {
+ u64 magic;
+ u64 size;
+};
+
struct perf_header;

int perf_file_header__read(struct perf_file_header *self,
@@ -60,8 +65,9 @@ struct perf_header {
int perf_header__init(struct perf_header *self);
void perf_header__exit(struct perf_header *self);

-int perf_header__read(struct perf_header *self, int fd);
+int perf_header__read(struct perf_session *session, int fd);
int perf_header__write(struct perf_header *self, int fd, bool at_exit);
+int perf_header__write_pipe(struct perf_header *self, int fd);

int perf_header__add_attr(struct perf_header *self,
struct perf_header_attr *attr);
diff --git a/tools/perf/util/session.c b/tools/perf/util/session.c
index dd1e923..3a3db33 100644
--- a/tools/perf/util/session.c
+++ b/tools/perf/util/session.c
@@ -18,7 +18,7 @@ static int perf_session__open(struct perf_session *self, bool force)
self->fd_pipe = true;
self->fd = STDIN_FILENO;

- if (perf_header__read(&self->header, self->fd) < 0)
+ if (perf_header__read(self, self->fd) < 0)
pr_err("incompatible file format");

return 0;
@@ -48,12 +48,13 @@ static int perf_session__open(struct perf_session *self, bool force)
goto out_close;
}

- if (perf_header__read(&self->header, self->fd) < 0) {
+ self->size = input_stat.st_size;
+
+ if (perf_header__read(self, self->fd) < 0) {
pr_err("incompatible file format");
goto out_close;
}

- self->size = input_stat.st_size;
return 0;

out_close:
@@ -67,6 +68,11 @@ static inline int perf_session__create_kernel_maps(struct perf_session *self)
return map_groups__create_kernel_maps(&self->kmaps, self->vmlinux_maps);
}

+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;
@@ -99,7 +105,7 @@ 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:
@@ -205,6 +211,26 @@ static void perf_event_ops__fill_defaults(struct perf_event_ops *handler)
handler->unthrottle = process_event_stub;
}

+static int process_event_stop(event_t *event __used,
+ struct perf_session *session __used)
+{
+ dump_printf(": stop!\n");
+ return PERF_PROCESS_EVENT_STOP;
+}
+
+void perf_event_ops__fill_stop(struct perf_event_ops *handler)
+{
+ handler->sample = process_event_stop;
+ handler->mmap = process_event_stop;
+ handler->comm = process_event_stop;
+ handler->fork = process_event_stop;
+ handler->exit = process_event_stop;
+ handler->lost = process_event_stop;
+ handler->read = process_event_stop;
+ handler->throttle = process_event_stop;
+ handler->unthrottle = process_event_stop;
+}
+
static const char *event__name[] = {
[0] = "TOTAL",
[PERF_RECORD_MMAP] = "MMAP",
@@ -218,14 +244,17 @@ 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)
@@ -289,7 +318,7 @@ 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,
@@ -299,7 +328,7 @@ 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]);
@@ -394,6 +423,96 @@ static struct thread *perf_session__register_idle_thread(struct perf_session *se
return thread;
}

+static int do_read(int fd, void *buf, size_t size)
+{
+ while (size) {
+ int ret = read(fd, buf, size);
+
+ if (ret <= 0)
+ return -1;
+
+ size -= ret;
+ buf += ret;
+ }
+
+ return 0;
+}
+
+#define is_done() (*(volatile int *)(&done))
+volatile int done;
+
+static int __perf_session__process_events_pipe(struct perf_session *self,
+ struct perf_event_ops *ops)
+{
+ int action = 0;
+ event_t event;
+ uint32_t size;
+ 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) {
+ 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) {
+ pr_err("failed to read event payload\n");
+ goto out_err;
+ }
+
+ if (size == 0 ||
+ (action = 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 (action == PERF_PROCESS_EVENT_STOP) {
+ self->header.data_offset = head;
+ goto done;
+ }
+
+ if (action >= PERF_PROCESS_EVENT_MAX)
+ head += action;
+
+ if (!is_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)
@@ -511,9 +630,13 @@ 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_events_pipe(self, ops);
out_err:
return err;
}
diff --git a/tools/perf/util/session.h b/tools/perf/util/session.h
index dbfb74a..ab1fcbf 100644
--- a/tools/perf/util/session.h
+++ b/tools/perf/util/session.h
@@ -46,6 +46,18 @@ struct perf_event_ops {
unthrottle;
};

+/*
+ * interpret process_event return values as actions.
+ * PERF_PROCESS_EVENT_MAX or greater is interpreted as 'skip ahead
+ * that many bytes'. Since that can never be less than
+ * sizeof(perf_event_header), 1 through sizeof(perf_event_header) can
+ * be interpreted as 'actions'.
+*/
+enum perf_process_event_action {
+ PERF_PROCESS_EVENT_STOP = 1,
+ PERF_PROCESS_EVENT_MAX
+};
+
struct perf_session *perf_session__new(const char *filename, int mode, bool force);
void perf_session__delete(struct perf_session *self);

@@ -86,4 +98,8 @@ static inline struct map *
{
return map_groups__new_module(&self->kmaps, start, filename);
}
+
+void perf_session__update_sample_type(struct perf_session *self);
+void perf_event_ops__fill_stop(struct perf_event_ops *handler);
+
#endif /* __PERF_SESSION_H */
--
1.6.4.GIT


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