Merge branch 'perf/core' into perf/probes

Resolved merge conflict in tools/perf/Makefile

Merge reason: we want to queue up a dependent patch.

Signed-off-by: Ingo Molnar <mingo@elte.hu>

18 files changed, 1173 insertions, 268 deletions

diff --git a/tools/perf/util/data_map.c b/tools/perf/util/data_map.c
index 18accb8fee4d..14cb8465eb08 100644
--- a/tools/perf/util/data_map.c
+++ b/tools/perf/util/data_map.c
@@ -70,6 +70,35 @@ process_event(event_t *event, unsigned long offset, unsigned long head)
 	}
 }
 
+int perf_header__read_build_ids(int input, off_t offset, off_t size)
+{
+	struct build_id_event bev;
+	char filename[PATH_MAX];
+	off_t limit = offset + size;
+	int err = -1;
+
+	while (offset < limit) {
+		struct dso *dso;
+		ssize_t len;
+
+		if (read(input, &bev, sizeof(bev)) != sizeof(bev))
+			goto out;
+
+		len = bev.header.size - sizeof(bev);
+		if (read(input, filename, len) != len)
+			goto out;
+
+		dso = dsos__findnew(filename);
+		if (dso != NULL)
+			dso__set_build_id(dso, &bev.build_id);
+
+		offset += bev.header.size;
+	}
+	err = 0;
+out:
+	return err;
+}
+
 int mmap_dispatch_perf_file(struct perf_header **pheader,
 			    const char *input_name,
 			    int force,
@@ -130,7 +159,7 @@ int mmap_dispatch_perf_file(struct perf_header **pheader,
 		if (curr_handler->sample_type_check(sample_type) < 0)
 			exit(-1);
 
-	if (load_kernel(0, NULL) < 0) {
+	if (load_kernel(NULL) < 0) {
 		perror("failed to load kernel symbols");
 		return EXIT_FAILURE;
 	}
diff --git a/tools/perf/util/data_map.h b/tools/perf/util/data_map.h
index 716d1053b074..ae036ecd7625 100644
--- a/tools/perf/util/data_map.h
+++ b/tools/perf/util/data_map.h
@@ -27,5 +27,6 @@ int mmap_dispatch_perf_file(struct perf_header **pheader,
 			    int full_paths,
 			    int *cwdlen,
 			    char **cwd);
+int perf_header__read_build_ids(int input, off_t offset, off_t file_size);
 
 #endif
diff --git a/tools/perf/util/debug.h b/tools/perf/util/debug.h
index e8b18a1f87a4..c6c24c522dea 100644
--- a/tools/perf/util/debug.h
+++ b/tools/perf/util/debug.h
@@ -2,6 +2,8 @@
 #ifndef __PERF_DEBUG_H
 #define __PERF_DEBUG_H
 
+#include "event.h"
+
 extern int verbose;
 extern int dump_trace;
 
diff --git a/tools/perf/util/debugfs.c b/tools/perf/util/debugfs.c
new file mode 100644
index 000000000000..06b73ee02c49
--- /dev/null
+++ b/tools/perf/util/debugfs.c
@@ -0,0 +1,241 @@
+#include "util.h"
+#include "debugfs.h"
+#include "cache.h"
+
+static int debugfs_premounted;
+static char debugfs_mountpoint[MAX_PATH+1];
+
+static const char *debugfs_known_mountpoints[] = {
+	"/sys/kernel/debug/",
+	"/debug/",
+	0,
+};
+
+/* use this to force a umount */
+void debugfs_force_cleanup(void)
+{
+	debugfs_find_mountpoint();
+	debugfs_premounted = 0;
+	debugfs_umount();
+}
+
+/* construct a full path to a debugfs element */
+int debugfs_make_path(const char *element, char *buffer, int size)
+{
+	int len;
+
+	if (strlen(debugfs_mountpoint) == 0) {
+		buffer[0] = '\0';
+		return -1;
+	}
+
+	len = strlen(debugfs_mountpoint) + strlen(element) + 1;
+	if (len >= size)
+		return len+1;
+
+	snprintf(buffer, size-1, "%s/%s", debugfs_mountpoint, element);
+	return 0;
+}
+
+static int debugfs_found;
+
+/* find the path to the mounted debugfs */
+const char *debugfs_find_mountpoint(void)
+{
+	const char **ptr;
+	char type[100];
+	FILE *fp;
+
+	if (debugfs_found)
+		return (const char *) debugfs_mountpoint;
+
+	ptr = debugfs_known_mountpoints;
+	while (*ptr) {
+		if (debugfs_valid_mountpoint(*ptr) == 0) {
+			debugfs_found = 1;
+			strcpy(debugfs_mountpoint, *ptr);
+			return debugfs_mountpoint;
+		}
+		ptr++;
+	}
+
+	/* give up and parse /proc/mounts */
+	fp = fopen("/proc/mounts", "r");
+	if (fp == NULL)
+		die("Can't open /proc/mounts for read");
+
+	while (fscanf(fp, "%*s %"
+		      STR(MAX_PATH)
+		      "s %99s %*s %*d %*d\n",
+		      debugfs_mountpoint, type) == 2) {
+		if (strcmp(type, "debugfs") == 0)
+			break;
+	}
+	fclose(fp);
+
+	if (strcmp(type, "debugfs") != 0)
+		return NULL;
+
+	debugfs_found = 1;
+
+	return debugfs_mountpoint;
+}
+
+/* verify that a mountpoint is actually a debugfs instance */
+
+int debugfs_valid_mountpoint(const char *debugfs)
+{
+	struct statfs st_fs;
+
+	if (statfs(debugfs, &st_fs) < 0)
+		return -ENOENT;
+	else if (st_fs.f_type != (long) DEBUGFS_MAGIC)
+		return -ENOENT;
+
+	return 0;
+}
+
+
+int debugfs_valid_entry(const char *path)
+{
+	struct stat st;
+
+	if (stat(path, &st))
+		return -errno;
+
+	return 0;
+}
+
+/* mount the debugfs somewhere */
+
+int debugfs_mount(const char *mountpoint)
+{
+	char mountcmd[128];
+
+	/* see if it's already mounted */
+	if (debugfs_find_mountpoint()) {
+		debugfs_premounted = 1;
+		return 0;
+	}
+
+	/* if not mounted and no argument */
+	if (mountpoint == NULL) {
+		/* see if environment variable set */
+		mountpoint = getenv(PERF_DEBUGFS_ENVIRONMENT);
+		/* if no environment variable, use default */
+		if (mountpoint == NULL)
+			mountpoint = "/sys/kernel/debug";
+	}
+
+	/* save the mountpoint */
+	strncpy(debugfs_mountpoint, mountpoint, sizeof(debugfs_mountpoint));
+
+	/* mount it */
+	snprintf(mountcmd, sizeof(mountcmd),
+		 "/bin/mount -t debugfs debugfs %s", mountpoint);
+	return system(mountcmd);
+}
+
+/* umount the debugfs */
+
+int debugfs_umount(void)
+{
+	char umountcmd[128];
+	int ret;
+
+	/* if it was already mounted, leave it */
+	if (debugfs_premounted)
+		return 0;
+
+	/* make sure it's a valid mount point */
+	ret = debugfs_valid_mountpoint(debugfs_mountpoint);
+	if (ret)
+		return ret;
+
+	snprintf(umountcmd, sizeof(umountcmd),
+		 "/bin/umount %s", debugfs_mountpoint);
+	return system(umountcmd);
+}
+
+int debugfs_write(const char *entry, const char *value)
+{
+	char path[MAX_PATH+1];
+	int ret, count;
+	int fd;
+
+	/* construct the path */
+	snprintf(path, sizeof(path), "%s/%s", debugfs_mountpoint, entry);
+
+	/* verify that it exists */
+	ret = debugfs_valid_entry(path);
+	if (ret)
+		return ret;
+
+	/* get how many chars we're going to write */
+	count = strlen(value);
+
+	/* open the debugfs entry */
+	fd = open(path, O_RDWR);
+	if (fd < 0)
+		return -errno;
+
+	while (count > 0) {
+		/* write it */
+		ret = write(fd, value, count);
+		if (ret <= 0) {
+			if (ret == EAGAIN)
+				continue;
+			close(fd);
+			return -errno;
+		}
+		count -= ret;
+	}
+
+	/* close it */
+	close(fd);
+
+	/* return success */
+	return 0;
+}
+
+/*
+ * read a debugfs entry
+ * returns the number of chars read or a negative errno
+ */
+int debugfs_read(const char *entry, char *buffer, size_t size)
+{
+	char path[MAX_PATH+1];
+	int ret;
+	int fd;
+
+	/* construct the path */
+	snprintf(path, sizeof(path), "%s/%s", debugfs_mountpoint, entry);
+
+	/* verify that it exists */
+	ret = debugfs_valid_entry(path);
+	if (ret)
+		return ret;
+
+	/* open the debugfs entry */
+	fd = open(path, O_RDONLY);
+	if (fd < 0)
+		return -errno;
+
+	do {
+		/* read it */
+		ret = read(fd, buffer, size);
+		if (ret == 0) {
+			close(fd);
+			return EOF;
+		}
+	} while (ret < 0 && errno == EAGAIN);
+
+	/* close it */
+	close(fd);
+
+	/* make *sure* there's a null character at the end */
+	buffer[ret] = '\0';
+
+	/* return the number of chars read */
+	return ret;
+}
diff --git a/tools/perf/util/debugfs.h b/tools/perf/util/debugfs.h
new file mode 100644
index 000000000000..3cd14f9ae784
--- /dev/null
+++ b/tools/perf/util/debugfs.h
@@ -0,0 +1,25 @@
+#ifndef __DEBUGFS_H__
+#define __DEBUGFS_H__
+
+#include <sys/mount.h>
+
+#ifndef MAX_PATH
+# define MAX_PATH 256
+#endif
+
+#ifndef STR
+# define _STR(x) #x
+# define STR(x) _STR(x)
+#endif
+
+extern const char *debugfs_find_mountpoint(void);
+extern int debugfs_valid_mountpoint(const char *debugfs);
+extern int debugfs_valid_entry(const char *path);
+extern int debugfs_mount(const char *mountpoint);
+extern int debugfs_umount(void);
+extern int debugfs_write(const char *entry, const char *value);
+extern int debugfs_read(const char *entry, char *buffer, size_t size);
+extern void debugfs_force_cleanup(void);
+extern int debugfs_make_path(const char *element, char *buffer, int size);
+
+#endif /* __DEBUGFS_H__ */
diff --git a/tools/perf/util/event.c b/tools/perf/util/event.c
new file mode 100644
index 000000000000..1dae7e3b400d
--- /dev/null
+++ b/tools/perf/util/event.c
@@ -0,0 +1,177 @@
+#include <linux/types.h>
+#include "event.h"
+#include "debug.h"
+#include "string.h"
+
+static pid_t event__synthesize_comm(pid_t pid, int full,
+				    int (*process)(event_t *event))
+{
+	event_t ev;
+	char filename[PATH_MAX];
+	char bf[BUFSIZ];
+	FILE *fp;
+	size_t size = 0;
+	DIR *tasks;
+	struct dirent dirent, *next;
+	pid_t tgid = 0;
+
+	snprintf(filename, sizeof(filename), "/proc/%d/status", pid);
+
+	fp = fopen(filename, "r");
+	if (fp == NULL) {
+out_race:
+		/*
+		 * We raced with a task exiting - just return:
+		 */
+		pr_debug("couldn't open %s\n", filename);
+		return 0;
+	}
+
+	memset(&ev.comm, 0, sizeof(ev.comm));
+	while (!ev.comm.comm[0] || !ev.comm.pid) {
+		if (fgets(bf, sizeof(bf), fp) == NULL)
+			goto out_failure;
+
+		if (memcmp(bf, "Name:", 5) == 0) {
+			char *name = bf + 5;
+			while (*name && isspace(*name))
+				++name;
+			size = strlen(name) - 1;
+			memcpy(ev.comm.comm, name, size++);
+		} else if (memcmp(bf, "Tgid:", 5) == 0) {
+			char *tgids = bf + 5;
+			while (*tgids && isspace(*tgids))
+				++tgids;
+			tgid = ev.comm.pid = atoi(tgids);
+		}
+	}
+
+	ev.comm.header.type = PERF_RECORD_COMM;
+	size = ALIGN(size, sizeof(u64));
+	ev.comm.header.size = sizeof(ev.comm) - (sizeof(ev.comm.comm) - size);
+
+	if (!full) {
+		ev.comm.tid = pid;
+
+		process(&ev);
+		goto out_fclose;
+	}
+
+	snprintf(filename, sizeof(filename), "/proc/%d/task", pid);
+
+	tasks = opendir(filename);
+	if (tasks == NULL)
+		goto out_race;
+
+	while (!readdir_r(tasks, &dirent, &next) && next) {
+		char *end;
+		pid = strtol(dirent.d_name, &end, 10);
+		if (*end)
+			continue;
+
+		ev.comm.tid = pid;
+
+		process(&ev);
+	}
+	closedir(tasks);
+
+out_fclose:
+	fclose(fp);
+	return tgid;
+
+out_failure:
+	pr_warning("couldn't get COMM and pgid, malformed %s\n", filename);
+	return -1;
+}
+
+static int event__synthesize_mmap_events(pid_t pid, pid_t tgid,
+					 int (*process)(event_t *event))
+{
+	char filename[PATH_MAX];
+	FILE *fp;
+
+	snprintf(filename, sizeof(filename), "/proc/%d/maps", pid);
+
+	fp = fopen(filename, "r");
+	if (fp == NULL) {
+		/*
+		 * We raced with a task exiting - just return:
+		 */
+		pr_debug("couldn't open %s\n", filename);
+		return -1;
+	}
+
+	while (1) {
+		char bf[BUFSIZ], *pbf = bf;
+		event_t ev = {
+			.header = { .type = PERF_RECORD_MMAP },
+		};
+		int n;
+		size_t size;
+		if (fgets(bf, sizeof(bf), fp) == NULL)
+			break;
+
+		/* 00400000-0040c000 r-xp 00000000 fd:01 41038  /bin/cat */
+		n = hex2u64(pbf, &ev.mmap.start);
+		if (n < 0)
+			continue;
+		pbf += n + 1;
+		n = hex2u64(pbf, &ev.mmap.len);
+		if (n < 0)
+			continue;
+		pbf += n + 3;
+		if (*pbf == 'x') { /* vm_exec */
+			char *execname = strchr(bf, '/');
+
+			/* Catch VDSO */
+			if (execname == NULL)
+				execname = strstr(bf, "[vdso]");
+
+			if (execname == NULL)
+				continue;
+
+			size = strlen(execname);
+			execname[size - 1] = '\0'; /* Remove \n */
+			memcpy(ev.mmap.filename, execname, size);
+			size = ALIGN(size, sizeof(u64));
+			ev.mmap.len -= ev.mmap.start;
+			ev.mmap.header.size = (sizeof(ev.mmap) -
+					       (sizeof(ev.mmap.filename) - size));
+			ev.mmap.pid = tgid;
+			ev.mmap.tid = pid;
+
+			process(&ev);
+		}
+	}
+
+	fclose(fp);
+	return 0;
+}
+
+int event__synthesize_thread(pid_t pid, int (*process)(event_t *event))
+{
+	pid_t tgid = event__synthesize_comm(pid, 1, process);
+	if (tgid == -1)
+		return -1;
+	return event__synthesize_mmap_events(pid, tgid, process);
+}
+
+void event__synthesize_threads(int (*process)(event_t *event))
+{
+	DIR *proc;
+	struct dirent dirent, *next;
+
+	proc = opendir("/proc");
+
+	while (!readdir_r(proc, &dirent, &next) && next) {
+		char *end;
+		pid_t pid = strtol(dirent.d_name, &end, 10);
+
+		if (*end) /* only interested in proper numerical dirents */
+			continue;
+
+		event__synthesize_thread(pid, process);
+	}
+
+	closedir(proc);
+}
diff --git a/tools/perf/util/event.h b/tools/perf/util/event.h
index d972b4b0d38c..1f771ce3a957 100644
--- a/tools/perf/util/event.h
+++ b/tools/perf/util/event.h
@@ -61,6 +61,20 @@ struct sample_event{
 	u64 array[];
 };
 
+#define BUILD_ID_SIZE 20
+
+struct build_id_event {
+	struct perf_event_header header;
+	u8			 build_id[ALIGN(BUILD_ID_SIZE, sizeof(u64))];
+	char			 filename[];
+};
+
+struct build_id_list {
+	struct build_id_event	event;
+	struct list_head	list;
+	const char		*dso_name;
+	int			len;
+};
 
 typedef union event_union {
 	struct perf_event_header	header;
@@ -105,10 +119,15 @@ struct symbol;
 
 typedef int (*symbol_filter_t)(struct map *map, struct symbol *sym);
 
-struct map *map__new(struct mmap_event *event, char *cwd, int cwdlen,
-		     unsigned int sym_priv_size, symbol_filter_t filter);
+void map__init(struct map *self, u64 start, u64 end, u64 pgoff,
+	       struct dso *dso);
+struct map *map__new(struct mmap_event *event, char *cwd, int cwdlen);
 struct map *map__clone(struct map *self);
 int map__overlap(struct map *l, struct map *r);
 size_t map__fprintf(struct map *self, FILE *fp);
+struct symbol *map__find_symbol(struct map *self, u64 ip, symbol_filter_t filter);
+
+int event__synthesize_thread(pid_t pid, int (*process)(event_t *event));
+void event__synthesize_threads(int (*process)(event_t *event));
 
 #endif /* __PERF_RECORD_H */
diff --git a/tools/perf/util/header.c b/tools/perf/util/header.c
index 7d26659b806c..b01a9537977f 100644
--- a/tools/perf/util/header.c
+++ b/tools/perf/util/header.c
@@ -2,11 +2,15 @@
 #include <unistd.h>
 #include <stdio.h>
 #include <stdlib.h>
+#include <linux/list.h>
 
 #include "util.h"
 #include "header.h"
 #include "../perf.h"
 #include "trace-event.h"
+#include "symbol.h"
+#include "data_map.h"
+#include "debug.h"
 
 /*
  * Create new perf.data header attribute:
@@ -15,32 +19,43 @@ struct perf_header_attr *perf_header_attr__new(struct perf_event_attr *attr)
 {
 	struct perf_header_attr *self = malloc(sizeof(*self));
 
-	if (!self)
-		die("nomem");
-
-	self->attr = *attr;
-	self->ids = 0;
-	self->size = 1;
-	self->id = malloc(sizeof(u64));
-
-	if (!self->id)
-		die("nomem");
+	if (self != NULL) {
+		self->attr = *attr;
+		self->ids  = 0;
+		self->size = 1;
+		self->id   = malloc(sizeof(u64));
+		if (self->id == NULL) {
+			free(self);
+			self = NULL;
+		}
+	}
 
 	return self;
 }
 
-void perf_header_attr__add_id(struct perf_header_attr *self, u64 id)
+void perf_header_attr__delete(struct perf_header_attr *self)
+{
+	free(self->id);
+	free(self);
+}
+
+int perf_header_attr__add_id(struct perf_header_attr *self, u64 id)
 {
 	int pos = self->ids;
 
 	self->ids++;
 	if (self->ids > self->size) {
-		self->size *= 2;
-		self->id = realloc(self->id, self->size * sizeof(u64));
-		if (!self->id)
-			die("nomem");
+		int nsize = self->size * 2;
+		u64 *nid = realloc(self->id, nsize * sizeof(u64));
+
+		if (nid == NULL)
+			return -1;
+
+		self->size = nsize;
+		self->id = nid;
 	}
 	self->id[pos] = id;
+	return 0;
 }
 
 /*
@@ -50,34 +65,41 @@ struct perf_header *perf_header__new(void)
 {
 	struct perf_header *self = calloc(sizeof(*self), 1);
 
-	if (!self)
-		die("nomem");
-
-	self->size = 1;
-	self->attr = malloc(sizeof(void *));
+	if (self != NULL) {
+		self->size = 1;
+		self->attr = malloc(sizeof(void *));
 
-	if (!self->attr)
-		die("nomem");
+		if (self->attr == NULL) {
+			free(self);
+			self = NULL;
+		}
+	}
 
 	return self;
 }
 
-void perf_header__add_attr(struct perf_header *self,
-			   struct perf_header_attr *attr)
+int perf_header__add_attr(struct perf_header *self,
+			  struct perf_header_attr *attr)
 {
 	int pos = self->attrs;
 
 	if (self->frozen)
-		die("frozen");
+		return -1;
 
 	self->attrs++;
 	if (self->attrs > self->size) {
-		self->size *= 2;
-		self->attr = realloc(self->attr, self->size * sizeof(void *));
-		if (!self->attr)
-			die("nomem");
+		int nsize = self->size * 2;
+		struct perf_header_attr **nattr;
+
+		nattr = realloc(self->attr, nsize * sizeof(void *));
+		if (nattr == NULL)
+			return -1;
+
+		self->size = nsize;
+		self->attr = nattr;
 	}
 	self->attr[pos] = attr;
+	return 0;
 }
 
 #define MAX_EVENT_NAME 64
@@ -124,71 +146,110 @@ static const char *__perf_magic = "PERFFILE";
 
 #define PERF_MAGIC	(*(u64 *)__perf_magic)
 
-struct perf_file_section {
-	u64 offset;
-	u64 size;
-};
-
 struct perf_file_attr {
 	struct perf_event_attr	attr;
 	struct perf_file_section	ids;
 };
 
-struct perf_file_header {
-	u64				magic;
-	u64				size;
-	u64				attr_size;
-	struct perf_file_section	attrs;
-	struct perf_file_section	data;
-	struct perf_file_section	event_types;
-	DECLARE_BITMAP(adds_features, HEADER_FEAT_BITS);
-};
+void perf_header__set_feat(struct perf_header *self, int feat)
+{
+	set_bit(feat, self->adds_features);
+}
 
-void perf_header__feat_trace_info(struct perf_header *header)
+bool perf_header__has_feat(const struct perf_header *self, int feat)
 {
-	set_bit(HEADER_TRACE_INFO, header->adds_features);
+	return test_bit(feat, self->adds_features);
 }
 
-static void do_write(int fd, void *buf, size_t size)
+static int do_write(int fd, const void *buf, size_t size)
 {
 	while (size) {
 		int ret = write(fd, buf, size);
 
 		if (ret < 0)
-			die("failed to write");
+			return -1;
 
 		size -= ret;
 		buf += ret;
 	}
+
+	return 0;
+}
+
+static int write_buildid_table(int fd, struct list_head *id_head)
+{
+	struct build_id_list *iter, *next;
+
+	list_for_each_entry_safe(iter, next, id_head, list) {
+		struct build_id_event *b = &iter->event;
+
+		if (do_write(fd, b, sizeof(*b)) < 0 ||
+		    do_write(fd, iter->dso_name, iter->len) < 0)
+			return -1;
+		list_del(&iter->list);
+		free(iter);
+	}
+
+	return 0;
 }
 
-static void perf_header__adds_write(struct perf_header *self, int fd)
+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 = self->adds_features;
+	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++];
 
-	if (test_bit(HEADER_TRACE_INFO, feat_mask)) {
 		/* 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;
 	}
-};
 
-void perf_header__write(struct perf_header *self, int fd)
+
+	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);
+		if (write_buildid_table(fd, &id_list) < 0)
+			die("failed to write buildid table");
+		buildid_sec->size = lseek(fd, 0, SEEK_CUR) - buildid_sec->offset;
+	}
+
+	lseek(fd, sec_start, SEEK_SET);
+	if (do_write(fd, feat_sec, sec_size) < 0)
+		die("failed to write feature section");
+	free(feat_sec);
+}
+
+void perf_header__write(struct perf_header *self, int fd, bool at_exit)
 {
 	struct perf_file_header f_header;
 	struct perf_file_attr   f_attr;
@@ -202,7 +263,8 @@ void perf_header__write(struct perf_header *self, int fd)
 		attr = self->attr[i];
 
 		attr->id_offset = lseek(fd, 0, SEEK_CUR);
-		do_write(fd, attr->id, attr->ids * sizeof(u64));
+		if (do_write(fd, attr->id, attr->ids * sizeof(u64)) < 0)
+			die("failed to write perf header");
 	}
 
 
@@ -218,18 +280,21 @@ void perf_header__write(struct perf_header *self, int fd)
 				.size   = attr->ids * sizeof(u64),
 			}
 		};
-		do_write(fd, &f_attr, sizeof(f_attr));
+		if (do_write(fd, &f_attr, sizeof(f_attr)) < 0)
+			die("failed to write perf header attribute");
 	}
 
 	self->event_offset = lseek(fd, 0, SEEK_CUR);
 	self->event_size = event_count * sizeof(struct perf_trace_event_type);
 	if (events)
-		do_write(fd, events, self->event_size);
-
-	perf_header__adds_write(self, fd);
+		if (do_write(fd, events, self->event_size) < 0)
+			die("failed to write perf header events");
 
 	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),
@@ -251,7 +316,8 @@ void perf_header__write(struct perf_header *self, int fd)
 	memcpy(&f_header.adds_features, &self->adds_features, sizeof(self->adds_features));
 
 	lseek(fd, 0, SEEK_SET);
-	do_write(fd, &f_header, sizeof(f_header));
+	if (do_write(fd, &f_header, sizeof(f_header)) < 0)
+		die("failed to write perf header");
 	lseek(fd, self->data_offset + self->data_size, SEEK_SET);
 
 	self->frozen = 1;
@@ -272,43 +338,112 @@ static void do_read(int fd, void *buf, size_t size)
 	}
 }
 
-static void perf_header__adds_read(struct perf_header *self, int fd)
+int perf_header__process_sections(struct perf_header *self, int fd,
+				  int (*process)(struct perf_file_section *self,
+						 int feat, int fd))
 {
-	const unsigned long *feat_mask = self->adds_features;
+	struct perf_file_section *feat_sec;
+	int nr_sections;
+	int sec_size;
+	int idx = 0;
+	int err = 0, feat = 1;
 
-	if (test_bit(HEADER_TRACE_INFO, feat_mask)) {
-		struct perf_file_section trace_sec;
+	nr_sections = bitmap_weight(self->adds_features, HEADER_FEAT_BITS);
+	if (!nr_sections)
+		return 0;
 
-		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);
+	feat_sec = calloc(sizeof(*feat_sec), nr_sections);
+	if (!feat_sec)
+		return -1;
+
+	sec_size = sizeof(*feat_sec) * nr_sections;
+
+	lseek(fd, self->data_offset + self->data_size, SEEK_SET);
+
+	do_read(fd, feat_sec, sec_size);
+
+	while (idx < nr_sections && feat < HEADER_LAST_FEATURE) {
+		if (perf_header__has_feat(self, feat)) {
+			struct perf_file_section *sec = &feat_sec[idx++];
+
+			err = process(sec, feat, fd);
+			if (err < 0)
+				break;
+		}
+		++feat;
 	}
+
+	free(feat_sec);
+	return err;
 };
 
+int perf_file_header__read(struct perf_file_header *self,
+			   struct perf_header *ph, int fd)
+{
+	lseek(fd, 0, SEEK_SET);
+	do_read(fd, self, sizeof(*self));
+
+	if (self->magic     != PERF_MAGIC ||
+	    self->attr_size != sizeof(struct perf_file_attr))
+		return -1;
+
+	if (self->size != sizeof(*self)) {
+		/* Support the previous format */
+		if (self->size == offsetof(typeof(*self), adds_features))
+			bitmap_zero(self->adds_features, HEADER_FEAT_BITS);
+		else
+			return -1;
+	}
+
+	memcpy(&ph->adds_features, &self->adds_features,
+	       sizeof(self->adds_features));
+
+	ph->event_offset = self->event_types.offset;
+	ph->event_size	 = self->event_types.size;
+	ph->data_offset	 = self->data.offset;
+	ph->data_size	 = self->data.size;
+	return 0;
+}
+
+static int perf_file_section__process(struct perf_file_section *self,
+				      int feat, int fd)
+{
+	if (lseek(fd, self->offset, SEEK_SET) < 0) {
+		pr_debug("Failed to lseek to %Ld offset for feature %d, "
+			 "continuing...\n", self->offset, feat);
+		return 0;
+	}
+
+	switch (feat) {
+	case HEADER_TRACE_INFO:
+		trace_report(fd);
+		break;
+
+	case HEADER_BUILD_ID:
+		if (perf_header__read_build_ids(fd, self->offset, self->size))
+			pr_debug("Failed to read buildids, continuing...\n");
+		break;
+	default:
+		pr_debug("unknown feature %d, continuing...\n", feat);
+	}
+
+	return 0;
+}
+
 struct perf_header *perf_header__read(int fd)
 {
 	struct perf_header	*self = perf_header__new();
 	struct perf_file_header f_header;
 	struct perf_file_attr	f_attr;
 	u64			f_id;
-
 	int nr_attrs, nr_ids, i, j;
 
-	lseek(fd, 0, SEEK_SET);
-	do_read(fd, &f_header, sizeof(f_header));
+	if (self == NULL)
+		die("nomem");
 
-	if (f_header.magic	!= PERF_MAGIC		||
-	    f_header.attr_size	!= sizeof(f_attr))
+	if (perf_file_header__read(&f_header, self, fd) < 0)
 		die("incompatible file format");
 
-	if (f_header.size != sizeof(f_header)) {
-		/* Support the previous format */
-		if (f_header.size == offsetof(typeof(f_header), adds_features))
-			bitmap_zero(f_header.adds_features, HEADER_FEAT_BITS);
-		else
-			die("incompatible file format");
-	}
 	nr_attrs = f_header.attrs.size / sizeof(f_attr);
 	lseek(fd, f_header.attrs.offset, SEEK_SET);
 
@@ -320,6 +455,8 @@ struct perf_header *perf_header__read(int fd)
 		tmp = lseek(fd, 0, SEEK_CUR);
 
 		attr = perf_header_attr__new(&f_attr.attr);
+		if (attr == NULL)
+			 die("nomem");
 
 		nr_ids = f_attr.ids.size / sizeof(u64);
 		lseek(fd, f_attr.ids.offset, SEEK_SET);
@@ -327,9 +464,12 @@ struct perf_header *perf_header__read(int fd)
 		for (j = 0; j < nr_ids; j++) {
 			do_read(fd, &f_id, sizeof(f_id));
 
-			perf_header_attr__add_id(attr, f_id);
+			if (perf_header_attr__add_id(attr, f_id) < 0)
+				die("nomem");
 		}
-		perf_header__add_attr(self, attr);
+		if (perf_header__add_attr(self, attr) < 0)
+			 die("nomem");
+
 		lseek(fd, tmp, SEEK_SET);
 	}
 
@@ -342,15 +482,7 @@ struct perf_header *perf_header__read(int fd)
 		event_count =  f_header.event_types.size / sizeof(struct perf_trace_event_type);
 	}
 
-	memcpy(&self->adds_features, &f_header.adds_features, sizeof(f_header.adds_features));
-
-	perf_header__adds_read(self, fd);
-
-	self->event_offset = f_header.event_types.offset;
-	self->event_size   = f_header.event_types.size;
-
-	self->data_offset = f_header.data.offset;
-	self->data_size   = f_header.data.size;
+	perf_header__process_sections(self, fd, perf_file_section__process);
 
 	lseek(fd, self->data_o