diff mbox series

[bpf-next,11/13] tools/bpf: refactor to implement btf_get_from_id() in lib/bpf

Message ID 20181012185526.2380717-2-yhs@fb.com
State Changes Requested, archived
Delegated to: BPF Maintainers
Headers show
Series bpf: add btf func info support | expand

Commit Message

Yonghong Song Oct. 12, 2018, 6:55 p.m. UTC 
The function get_btf() is implemented in tools/bpf/bpftool/map.c
to get a btf structure given a map_info. This patch
refactored this function to be function btf_get_from_id()
in tools/lib/bpf so that it can be used later.

Signed-off-by: Yonghong Song <yhs@fb.com>
---
 tools/bpf/bpftool/map.c | 68 ++--------------------------------------
 tools/lib/bpf/btf.c     | 69 +++++++++++++++++++++++++++++++++++++++++
 tools/lib/bpf/btf.h     |  1 +
 3 files changed, 72 insertions(+), 66 deletions(-)
diff mbox series

Patch

diff --git a/tools/bpf/bpftool/map.c b/tools/bpf/bpftool/map.c
index 9f5de48f8a99..33c7dc8ddd86 100644
--- a/tools/bpf/bpftool/map.c
+++ b/tools/bpf/bpftool/map.c
@@ -203,70 +203,6 @@  static int do_dump_btf(const struct btf_dumper *d,
 	return ret;
 }
 
-static int get_btf(struct bpf_map_info *map_info, struct btf **btf)
-{
-	struct bpf_btf_info btf_info = { 0 };
-	__u32 len = sizeof(btf_info);
-	__u32 last_size;
-	int btf_fd;
-	void *ptr;
-	int err;
-
-	err = 0;
-	*btf = NULL;
-	btf_fd = bpf_btf_get_fd_by_id(map_info->btf_id);
-	if (btf_fd < 0)
-		return 0;
-
-	/* we won't know btf_size until we call bpf_obj_get_info_by_fd(). so
-	 * let's start with a sane default - 4KiB here - and resize it only if
-	 * bpf_obj_get_info_by_fd() needs a bigger buffer.
-	 */
-	btf_info.btf_size = 4096;
-	last_size = btf_info.btf_size;
-	ptr = malloc(last_size);
-	if (!ptr) {
-		err = -ENOMEM;
-		goto exit_free;
-	}
-
-	bzero(ptr, last_size);
-	btf_info.btf = ptr_to_u64(ptr);
-	err = bpf_obj_get_info_by_fd(btf_fd, &btf_info, &len);
-
-	if (!err && btf_info.btf_size > last_size) {
-		void *temp_ptr;
-
-		last_size = btf_info.btf_size;
-		temp_ptr = realloc(ptr, last_size);
-		if (!temp_ptr) {
-			err = -ENOMEM;
-			goto exit_free;
-		}
-		ptr = temp_ptr;
-		bzero(ptr, last_size);
-		btf_info.btf = ptr_to_u64(ptr);
-		err = bpf_obj_get_info_by_fd(btf_fd, &btf_info, &len);
-	}
-
-	if (err || btf_info.btf_size > last_size) {
-		err = errno;
-		goto exit_free;
-	}
-
-	*btf = btf__new((__u8 *)btf_info.btf, btf_info.btf_size, NULL);
-	if (IS_ERR(*btf)) {
-		err = PTR_ERR(*btf);
-		*btf = NULL;
-	}
-
-exit_free:
-	close(btf_fd);
-	free(ptr);
-
-	return err;
-}
-
 static json_writer_t *get_btf_writer(void)
 {
 	json_writer_t *jw = jsonw_new(stdout);
@@ -753,7 +689,7 @@  static int do_dump(int argc, char **argv)
 
 	prev_key = NULL;
 
-	err = get_btf(&info, &btf);
+	err = btf_get_from_id(info.btf_id, &btf);
 	if (err) {
 		p_err("failed to get btf");
 		goto exit_free;
@@ -897,7 +833,7 @@  static int do_lookup(int argc, char **argv)
 	}
 
 	/* here means bpf_map_lookup_elem() succeeded */
-	err = get_btf(&info, &btf);
+	err = btf_get_from_id(info.btf_id, &btf);
 	if (err) {
 		p_err("failed to get btf");
 		goto exit_free;
diff --git a/tools/lib/bpf/btf.c b/tools/lib/bpf/btf.c
index 4748e0bacd2b..ab654628e966 100644
--- a/tools/lib/bpf/btf.c
+++ b/tools/lib/bpf/btf.c
@@ -42,6 +42,11 @@  struct btf_ext {
 	__u32 func_info_len;
 };
 
+static inline __u64 ptr_to_u64(const void *ptr)
+{
+	return (__u64) (unsigned long) ptr;
+}
+
 static int btf_add_type(struct btf *btf, struct btf_type *t)
 {
 	if (btf->types_size - btf->nr_types < 2) {
@@ -403,6 +408,70 @@  const char *btf__name_by_offset(const struct btf *btf, __u32 offset)
 		return NULL;
 }
 
+int btf_get_from_id(__u32 id, struct btf **btf)
+{
+	struct bpf_btf_info btf_info = { 0 };
+	__u32 len = sizeof(btf_info);
+	__u32 last_size;
+	int btf_fd;
+	void *ptr;
+	int err;
+
+	err = 0;
+	*btf = NULL;
+	btf_fd = bpf_btf_get_fd_by_id(id);
+	if (btf_fd < 0)
+		return 0;
+
+	/* we won't know btf_size until we call bpf_obj_get_info_by_fd(). so
+	 * let's start with a sane default - 4KiB here - and resize it only if
+	 * bpf_obj_get_info_by_fd() needs a bigger buffer.
+	 */
+	btf_info.btf_size = 4096;
+	last_size = btf_info.btf_size;
+	ptr = malloc(last_size);
+	if (!ptr) {
+		err = -ENOMEM;
+		goto exit_free;
+	}
+
+	bzero(ptr, last_size);
+	btf_info.btf = ptr_to_u64(ptr);
+	err = bpf_obj_get_info_by_fd(btf_fd, &btf_info, &len);
+
+	if (!err && btf_info.btf_size > last_size) {
+		void *temp_ptr;
+
+		last_size = btf_info.btf_size;
+		temp_ptr = realloc(ptr, last_size);
+		if (!temp_ptr) {
+			err = -ENOMEM;
+			goto exit_free;
+		}
+		ptr = temp_ptr;
+		bzero(ptr, last_size);
+		btf_info.btf = ptr_to_u64(ptr);
+		err = bpf_obj_get_info_by_fd(btf_fd, &btf_info, &len);
+	}
+
+	if (err || btf_info.btf_size > last_size) {
+		err = errno;
+		goto exit_free;
+	}
+
+	*btf = btf__new((__u8 *)btf_info.btf, btf_info.btf_size, NULL);
+	if (IS_ERR(*btf)) {
+		err = PTR_ERR(*btf);
+		*btf = NULL;
+	}
+
+exit_free:
+	close(btf_fd);
+	free(ptr);
+
+	return err;
+}
+
 static int btf_ext_validate_func_info(const struct btf_sec_func_info *sinfo,
 				      __u32 size, btf_print_fn_t err_log)
 {
diff --git a/tools/lib/bpf/btf.h b/tools/lib/bpf/btf.h
index 2bbcc9e41cf5..51e63da844e6 100644
--- a/tools/lib/bpf/btf.h
+++ b/tools/lib/bpf/btf.h
@@ -44,6 +44,7 @@  __s64 btf__resolve_size(const struct btf *btf, __u32 type_id);
 int btf__resolve_type(const struct btf *btf, __u32 type_id);
 int btf__fd(const struct btf *btf);
 const char *btf__name_by_offset(const struct btf *btf, __u32 offset);
+int btf_get_from_id(__u32 id, struct btf **btf);
 
 struct btf_ext *btf_ext__new(__u8 *data, __u32 size, btf_print_fn_t err_log);
 void btf_ext__free(struct btf_ext *btf_ext);