diff --git a/tools/perf/util/data_map.c b/tools/perf/util/data_map.c
index 66e58aa..aacb814 100644
--- a/tools/perf/util/data_map.c
+++ b/tools/perf/util/data_map.c
@@ -70,18 +70,15 @@
 	}
 }
 
-int perf_header__read_build_ids(const struct perf_header *self,
-				int input, off_t file_size)
+int perf_header__read_build_ids(int input, off_t size)
 {
-	off_t offset = self->data_offset + self->data_size;
 	struct build_id_event bev;
 	char filename[PATH_MAX];
+	off_t offset = lseek(input, 0, SEEK_CUR);
+	off_t limit = offset + size;
 	int err = -1;
 
-	if (lseek(input, offset, SEEK_SET) < 0)
-		return -1;
-
-	while (offset < file_size) {
+	while (offset < limit) {
 		struct dso *dso;
 		ssize_t len;
 
diff --git a/tools/perf/util/data_map.h b/tools/perf/util/data_map.h
index c412281..20b4037 100644
--- a/tools/perf/util/data_map.h
+++ b/tools/perf/util/data_map.h
@@ -27,7 +27,6 @@
 			    int full_paths,
 			    int *cwdlen,
 			    char **cwd);
-int perf_header__read_build_ids(const struct perf_header *self,
-				int input, off_t file_size);
+int perf_header__read_build_ids(int input, off_t file_size);
 
 #endif
diff --git a/tools/perf/util/header.c b/tools/perf/util/header.c
index 9709d38..ebed4f4 100644
--- a/tools/perf/util/header.c
+++ b/tools/perf/util/header.c
@@ -186,41 +186,58 @@
 }
 
 static void
-perf_header__adds_write(struct perf_header *self, int fd, bool at_exit)
+perf_header__adds_write(struct perf_header *self, int fd)
 {
-	struct perf_file_section trace_sec;
-	u64 cur_offset = lseek(fd, 0, SEEK_CUR);
+	LIST_HEAD(id_list);
+	int nr_sections;
+	struct perf_file_section *feat_sec;
+	int sec_size;
+	u64 sec_start;
+	int idx = 0;
+
+	if (fetch_build_id_table(&id_list))
+		perf_header__set_feat(self, HEADER_BUILD_ID);
+
+	nr_sections = bitmap_weight(self->adds_features, HEADER_FEAT_BITS);
+	if (!nr_sections)
+		return;
+
+	feat_sec = calloc(sizeof(*feat_sec), nr_sections);
+	if (!feat_sec)
+		die("No memory");
+
+	sec_size = sizeof(*feat_sec) * nr_sections;
+
+	sec_start = self->data_offset + self->data_size;
+	lseek(fd, sec_start + sec_size, SEEK_SET);
 
 	if (perf_header__has_feat(self, HEADER_TRACE_INFO)) {
+		struct perf_file_section *trace_sec;
+
+		trace_sec = &feat_sec[idx++];
+
 		/* Write trace info */
-		trace_sec.offset = lseek(fd, sizeof(trace_sec), SEEK_CUR);
+		trace_sec->offset = lseek(fd, 0, 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);
+		trace_sec->size = lseek(fd, 0, SEEK_CUR) - trace_sec->offset;
 	}
 
-	if (at_exit) {
-		LIST_HEAD(id_list);
 
-		if (fetch_build_id_table(&id_list)) {
-			lseek(fd, self->data_offset + self->data_size, SEEK_SET);
-			perf_header__set_feat(self, HEADER_BUILD_ID);
-			write_buildid_table(fd, &id_list);
-			lseek(fd, cur_offset, SEEK_SET);
-		}
+	if (perf_header__has_feat(self, HEADER_BUILD_ID)) {
+		struct perf_file_section *buildid_sec;
+
+		buildid_sec = &feat_sec[idx++];
+
+		/* Write build-ids */
+		buildid_sec->offset = lseek(fd, 0, SEEK_CUR);
+		write_buildid_table(fd, &id_list);
+		buildid_sec->size = lseek(fd, 0, SEEK_CUR) - buildid_sec->offset;
 	}
-};
+
+	lseek(fd, sec_start, SEEK_SET);
+	do_write(fd, feat_sec, sec_size);
+	free(feat_sec);
+}
 
 void perf_header__write(struct perf_header *self, int fd, bool at_exit)
 {
@@ -260,10 +277,11 @@
 	if (events)
 		do_write(fd, events, self->event_size);
 
-	perf_header__adds_write(self, fd, at_exit);
-
 	self->data_offset = lseek(fd, 0, SEEK_CUR);
 
+	if (at_exit)
+		perf_header__adds_write(self, fd);
+
 	f_header = (struct perf_file_header){
 		.magic	   = PERF_MAGIC,
 		.size	   = sizeof(f_header),
@@ -308,22 +326,44 @@
 
 static void perf_header__adds_read(struct perf_header *self, int fd)
 {
-	if (perf_header__has_feat(self, HEADER_TRACE_INFO)) {
-		struct perf_file_section trace_sec;
+	struct perf_file_section *feat_sec;
+	int nr_sections;
+	int sec_size;
+	int idx = 0;
 
-		do_read(fd, &trace_sec, sizeof(trace_sec));
-		lseek(fd, trace_sec.offset, SEEK_SET);
+
+	nr_sections = bitmap_weight(self->adds_features, HEADER_FEAT_BITS);
+	if (!nr_sections)
+		return;
+
+	feat_sec = calloc(sizeof(*feat_sec), nr_sections);
+	if (!feat_sec)
+		die("No memory");
+
+	sec_size = sizeof(*feat_sec) * nr_sections;
+
+	lseek(fd, self->data_offset + self->data_size, SEEK_SET);
+
+	do_read(fd, feat_sec, sec_size);
+
+	if (perf_header__has_feat(self, HEADER_TRACE_INFO)) {
+		struct perf_file_section *trace_sec;
+
+		trace_sec = &feat_sec[idx++];
+		lseek(fd, trace_sec->offset, SEEK_SET);
 		trace_report(fd);
-		lseek(fd, trace_sec.offset + trace_sec.size, SEEK_SET);
 	}
 
 	if (perf_header__has_feat(self, HEADER_BUILD_ID)) {
-		struct stat input_stat;
+		struct perf_file_section *buildid_sec;
 
-		fstat(fd, &input_stat);
-		if (perf_header__read_build_ids(self, fd, input_stat.st_size))
+		buildid_sec = &feat_sec[idx++];
+		lseek(fd, buildid_sec->offset, SEEK_SET);
+		if (perf_header__read_build_ids(fd, buildid_sec->size))
 			pr_debug("failed to read buildids, continuing...\n");
 	}
+
+	free(feat_sec);
 };
 
 struct perf_header *perf_header__read(int fd)
diff --git a/tools/perf/util/include/linux/bitmap.h b/tools/perf/util/include/linux/bitmap.h
index 821c103..9450763 100644
--- a/tools/perf/util/include/linux/bitmap.h
+++ b/tools/perf/util/include/linux/bitmap.h
@@ -1,2 +1,3 @@
 #include "../../../../include/linux/bitmap.h"
 #include "../../../../include/asm-generic/bitops/find.h"
+#include <linux/errno.h>
diff --git a/tools/perf/util/include/linux/ctype.h b/tools/perf/util/include/linux/ctype.h
index bae5783..a53d4ee 100644
--- a/tools/perf/util/include/linux/ctype.h
+++ b/tools/perf/util/include/linux/ctype.h
@@ -1 +1 @@
-#include "../../../../include/linux/ctype.h"
+#include "../util.h"
diff --git a/tools/perf/util/util.h b/tools/perf/util/util.h
index 9de2329..7bd5bda 100644
--- a/tools/perf/util/util.h
+++ b/tools/perf/util/util.h
@@ -306,6 +306,7 @@
 #undef isascii
 #undef isspace
 #undef isdigit
+#undef isxdigit
 #undef isalpha
 #undef isprint
 #undef isalnum
@@ -323,6 +324,8 @@
 #define isascii(x) (((x) & ~0x7f) == 0)
 #define isspace(x) sane_istest(x,GIT_SPACE)
 #define isdigit(x) sane_istest(x,GIT_DIGIT)
+#define isxdigit(x)	\
+	(sane_istest(toupper(x), GIT_ALPHA | GIT_DIGIT) && toupper(x) < 'G')
 #define isalpha(x) sane_istest(x,GIT_ALPHA)
 #define isalnum(x) sane_istest(x,GIT_ALPHA | GIT_DIGIT)
 #define isprint(x) sane_istest(x,GIT_PRINT)