perf tools: Introduce bitmask'ed additional headers

This provides a new set of bitmasked headers. A new field is
added in the perf headers that implements a bitmap storing
optional features present in the perf.data file.

The layout can be pictured like this:

(Usual perf headers)(Features bitmap)[Feature 0][Feature
n][Feature 255]

If the bit n is set, then the feature n is used in this file.
They are all set in order. This brings a backward and forward
compatibility.

The trace_info section has moved into such optional features,
this is the first and only one for now.

This is backward compatible with the .32 file version although
it doesn't support the previous separate trace.info file.

And finally it doesn't support the current interim development
version.

Signed-off-by: Frederic Weisbecker <fweisbec@gmail.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Arnaldo Carvalho de Melo <acme@redhat.com>
Cc: Mike Galbraith <efault@gmx.de>
Cc: Paul Mackerras <paulus@samba.org>
Cc: Steven Rostedt <rostedt@goodmis.org>
LKML-Reference: <1255792354-11304-2-git-send-email-fweisbec@gmail.com>
Signed-off-by: Ingo Molnar <mingo@elte.hu>

1 files changed, 56 insertions, 44 deletions

diff --git a/tools/perf/util/header.c b/tools/perf/util/header.c
index 9aae360c0f28..171d51b6f359 100644
--- a/tools/perf/util/header.c
+++ b/tools/perf/util/header.c
@@ -8,6 +8,8 @@
 #include "../perf.h"
 #include "trace-event.h"
 
+#include <linux/bitmap.h>
+
 /*
  * Create new perf.data header attribute:
  */
@@ -48,25 +50,17 @@ void perf_header_attr__add_id(struct perf_header_attr *self, u64 id)
  */
 struct perf_header *perf_header__new(void)
 {
-        struct perf_header *self = malloc(sizeof(*self));
+        struct perf_header *self = calloc(sizeof(*self), 1);
 
         if (!self)
                 die("nomem");
 
-        self->frozen = 0;
-
-        self->attrs = 0;
         self->size = 1;
         self->attr = malloc(sizeof(void *));
 
         if (!self->attr)
                 die("nomem");
 
-        self->data_offset = 0;
-        self->data_size = 0;
-        self->trace_info_offset = 0;
-        self->trace_info_size = 0;
-
         return self;
 }
 
@@ -149,14 +143,12 @@ struct perf_file_header {
         struct perf_file_section        attrs;
         struct perf_file_section        data;
         struct perf_file_section        event_types;
-        struct perf_file_section        trace_info;
+        feat_mask_t                     adds_features;
 };
 
-static int trace_info;
-
-void perf_header__set_trace_info(void)
+void perf_header__feat_trace_info(struct perf_header *header)
 {
-        trace_info = 1;
+        set_bit(HEADER_TRACE_INFO, perf_header__adds_mask(header));
 }
 
 static void do_write(int fd, void *buf, size_t size)
@@ -172,6 +164,32 @@ static void do_write(int fd, void *buf, size_t size)
         }
 }
 
+static void perf_header__adds_write(struct perf_header *self, int fd)
+{
+        struct perf_file_section trace_sec;
+        u64 cur_offset = lseek(fd, 0, SEEK_CUR);
+        unsigned long *feat_mask = perf_header__adds_mask(self);
+
+        if (test_bit(HEADER_TRACE_INFO, feat_mask)) {
+                /* Write trace info */
+                trace_sec.offset = lseek(fd, sizeof(trace_sec), SEEK_CUR);
+                read_tracing_data(fd, attrs, nr_counters);
+                trace_sec.size = lseek(fd, 0, SEEK_CUR) - trace_sec.offset;
+
+                /* Write trace info headers */
+                lseek(fd, cur_offset, SEEK_SET);
+                do_write(fd, &trace_sec, sizeof(trace_sec));
+
+                /*
+                 * Update cur_offset. So that other (future)
+                 * features can set their own infos in this place. But if we are
+                 * the only feature, at least that seeks to the place the data
+                 * should begin.
+                 */
+                cur_offset = lseek(fd, trace_sec.offset + trace_sec.size, SEEK_SET);
+        }
+};
+
 void perf_header__write(struct perf_header *self, int fd)
 {
         struct perf_file_header f_header;
@@ -210,23 +228,7 @@ void perf_header__write(struct perf_header *self, int fd)
         if (events)
                 do_write(fd, events, self->event_size);
 
-        if (trace_info) {
-                static int trace_info_written;
-
-                /*
-                 * Write it only once
-                 */
-                if (!trace_info_written) {
-                        self->trace_info_offset = lseek(fd, 0, SEEK_CUR);
-                        read_tracing_data(fd, attrs, nr_counters);
-                        self->trace_info_size = lseek(fd, 0, SEEK_CUR) -
-                                                self->trace_info_offset;
-                        trace_info_written = 1;
-                } else {
-                        lseek(fd, self->trace_info_offset +
-                                self->trace_info_size, SEEK_SET);
-                }
-        }
+        perf_header__adds_write(self, fd);
 
         self->data_offset = lseek(fd, 0, SEEK_CUR);
 
@@ -246,12 +248,10 @@ void perf_header__write(struct perf_header *self, int fd)
                         .offset = self->event_offset,
                         .size   = self->event_size,
                 },
-                .trace_info = {
-                        .offset = self->trace_info_offset,
-                        .size = self->trace_info_size,
-                },
         };
 
+        memcpy(&f_header.adds_features, &self->adds_features, sizeof(feat_mask_t));
+
         lseek(fd, 0, SEEK_SET);
         do_write(fd, &f_header, sizeof(f_header));
         lseek(fd, self->data_offset + self->data_size, SEEK_SET);
@@ -274,6 +274,20 @@ static void do_read(int fd, void *buf, size_t size)
         }
 }
 
+static void perf_header__adds_read(struct perf_header *self, int fd)
+{
+        const unsigned long *feat_mask = perf_header__adds_mask(self);
+
+        if (test_bit(HEADER_TRACE_INFO, feat_mask)) {
+                struct perf_file_section trace_sec;
+
+                do_read(fd, &trace_sec, sizeof(trace_sec));
+                lseek(fd, trace_sec.offset, SEEK_SET);
+                trace_report(fd);
+                lseek(fd, trace_sec.offset + trace_sec.size, SEEK_SET);
+        }
+};
+
 struct perf_header *perf_header__read(int fd)
 {
         struct perf_header      *self = perf_header__new();
@@ -292,9 +306,11 @@ struct perf_header *perf_header__read(int fd)
 
         if (f_header.size != sizeof(f_header)) {
                 /* Support the previous format */
-                if (f_header.size == offsetof(typeof(f_header), trace_info))
-                        f_header.trace_info.size = 0;
-                else
+                if (f_header.size == offsetof(typeof(f_header), adds_features)) {
+                        unsigned long *mask = (unsigned long *)(void *)
+                                        &f_header.adds_features;
+                        bitmap_zero(mask, HEADER_FEAT_BITS);
+                } else
                         die("incompatible file format");
         }
         nr_attrs = f_header.attrs.size / sizeof(f_attr);
@@ -330,13 +346,9 @@ struct perf_header *perf_header__read(int fd)
                 event_count =  f_header.event_types.size / sizeof(struct perf_trace_event_type);
         }
 
-        self->trace_info_offset = f_header.trace_info.offset;
-        self->trace_info_size = f_header.trace_info.size;
+        memcpy(&self->adds_features, &f_header.adds_features, sizeof(feat_mask_t));
 
-        if (self->trace_info_size) {
-                lseek(fd, self->trace_info_offset, SEEK_SET);
-                trace_report(fd);
-        }
+        perf_header__adds_read(self, fd);
 
         self->event_offset = f_header.event_types.offset;
         self->event_size   = f_header.event_types.size;