From: Andrii Nakryiko andrii@kernel.org
mainline inclusion from mainline-5.11-rc1 commit a19f93cfafdf85851c69bc9f677aa4f40c53610f category: feature bugzilla: https://gitee.com/openeuler/kernel/issues/I5EUVD CVE: NA
Reference: https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/commit/?i...
-------------------------------------------------
Add a btf_get_from_fd() helper, which constructs struct btf from in-kernel BTF data by FD. This is used for loading module BTFs.
Signed-off-by: Andrii Nakryiko andrii@kernel.org Signed-off-by: Alexei Starovoitov ast@kernel.org Link: https://lore.kernel.org/bpf/20201203204634.1325171-4-andrii@kernel.org (cherry picked from commit a19f93cfafdf85851c69bc9f677aa4f40c53610f) Signed-off-by: Wang Yufen wangyufen@huawei.com --- tools/lib/bpf/btf.c | 61 +++++++++++++++++++-------------- tools/lib/bpf/libbpf_internal.h | 1 + 2 files changed, 36 insertions(+), 26 deletions(-)
diff --git a/tools/lib/bpf/btf.c b/tools/lib/bpf/btf.c index cdf2f225f944..6225c403685a 100644 --- a/tools/lib/bpf/btf.c +++ b/tools/lib/bpf/btf.c @@ -1324,35 +1324,27 @@ const char *btf__name_by_offset(const struct btf *btf, __u32 offset) return btf__str_by_offset(btf, offset); }
-int btf__get_from_id(__u32 id, struct btf **btf) +struct btf *btf_get_from_fd(int btf_fd, struct btf *base_btf) { - struct bpf_btf_info btf_info = { 0 }; + struct bpf_btf_info btf_info; __u32 len = sizeof(btf_info); __u32 last_size; - int btf_fd; + struct btf *btf; 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; + last_size = 4096; ptr = malloc(last_size); - if (!ptr) { - err = -ENOMEM; - goto exit_free; - } + if (!ptr) + return ERR_PTR(-ENOMEM);
- memset(ptr, 0, last_size); + memset(&btf_info, 0, sizeof(btf_info)); btf_info.btf = ptr_to_u64(ptr); + btf_info.btf_size = last_size; err = bpf_obj_get_info_by_fd(btf_fd, &btf_info, &len);
if (!err && btf_info.btf_size > last_size) { @@ -1361,31 +1353,48 @@ int btf__get_from_id(__u32 id, struct btf **btf) last_size = btf_info.btf_size; temp_ptr = realloc(ptr, last_size); if (!temp_ptr) { - err = -ENOMEM; + btf = ERR_PTR(-ENOMEM); goto exit_free; } ptr = temp_ptr; - memset(ptr, 0, last_size); + + len = sizeof(btf_info); + memset(&btf_info, 0, sizeof(btf_info)); btf_info.btf = ptr_to_u64(ptr); + btf_info.btf_size = last_size; + err = bpf_obj_get_info_by_fd(btf_fd, &btf_info, &len); }
if (err || btf_info.btf_size > last_size) { - err = errno; + btf = err ? ERR_PTR(-errno) : ERR_PTR(-E2BIG); goto exit_free; }
- *btf = btf__new((__u8 *)(long)btf_info.btf, btf_info.btf_size); - if (IS_ERR(*btf)) { - err = PTR_ERR(*btf); - *btf = NULL; - } + btf = btf_new(ptr, btf_info.btf_size, base_btf);
exit_free: - close(btf_fd); free(ptr); + return btf; +}
- return err; +int btf__get_from_id(__u32 id, struct btf **btf) +{ + struct btf *res; + int btf_fd; + + *btf = NULL; + btf_fd = bpf_btf_get_fd_by_id(id); + if (btf_fd < 0) + return -errno; + + res = btf_get_from_fd(btf_fd, NULL); + close(btf_fd); + if (IS_ERR(res)) + return PTR_ERR(res); + + *btf = res; + return 0; }
int btf__get_map_kv_tids(const struct btf *btf, const char *map_name, diff --git a/tools/lib/bpf/libbpf_internal.h b/tools/lib/bpf/libbpf_internal.h index d99bc847bf84..e569ae63808e 100644 --- a/tools/lib/bpf/libbpf_internal.h +++ b/tools/lib/bpf/libbpf_internal.h @@ -155,6 +155,7 @@ int bpf_object__section_size(const struct bpf_object *obj, const char *name, __u32 *size); int bpf_object__variable_offset(const struct bpf_object *obj, const char *name, __u32 *off); +struct btf *btf_get_from_fd(int btf_fd, struct btf *base_btf);
struct btf_ext_info { /*