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authorMartin KaFai Lau <kafai@fb.com>2018-05-05 00:49:51 +0300
committerDaniel Borkmann <daniel@iogearbox.net>2018-05-09 18:25:13 +0300
commit78958fca7ead2f81b60a6827881c4866d1ed0c52 (patch)
tree541a6090ce06d7bc6f708f5a70a0cd4bff187ac2 /include/linux/btf.h
parent82e9697250977f3f87cd42e71e8daa8810e64520 (diff)
downloadlinux-78958fca7ead2f81b60a6827881c4866d1ed0c52.tar.xz
bpf: btf: Introduce BTF ID
This patch gives an ID to each loaded BTF. The ID is allocated by the idr like the existing prog-id and map-id. The bpf_put(map->btf) is moved to __bpf_map_put() so that the userspace can stop seeing the BTF ID ASAP when the last BTF refcnt is gone. It also makes BTF accessible from userspace through the 1. new BPF_BTF_GET_FD_BY_ID command. It is limited to CAP_SYS_ADMIN which is inline with the BPF_BTF_LOAD cmd and the existing BPF_[MAP|PROG]_GET_FD_BY_ID cmd. 2. new btf_id (and btf_key_id + btf_value_id) in "struct bpf_map_info" Once the BTF ID handler is accessible from userspace, freeing a BTF object has to go through a rcu period. The BPF_BTF_GET_FD_BY_ID cmd can then be done under a rcu_read_lock() instead of taking spin_lock. [Note: A similar rcu usage can be done to the existing bpf_prog_get_fd_by_id() in a follow up patch] When processing the BPF_BTF_GET_FD_BY_ID cmd, refcount_inc_not_zero() is needed because the BTF object could be already in the rcu dead row . btf_get() is removed since its usage is currently limited to btf.c alone. refcount_inc() is used directly instead. Signed-off-by: Martin KaFai Lau <kafai@fb.com> Acked-by: Alexei Starovoitov <ast@fb.com> Acked-by: Song Liu <songliubraving@fb.com> Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
Diffstat (limited to 'include/linux/btf.h')
-rw-r--r--include/linux/btf.h2
1 files changed, 2 insertions, 0 deletions
diff --git a/include/linux/btf.h b/include/linux/btf.h
index a966dc6d61ee..e076c4697049 100644
--- a/include/linux/btf.h
+++ b/include/linux/btf.h
@@ -44,5 +44,7 @@ const struct btf_type *btf_type_id_size(const struct btf *btf,
u32 *ret_size);
void btf_type_seq_show(const struct btf *btf, u32 type_id, void *obj,
struct seq_file *m);
+int btf_get_fd_by_id(u32 id);
+u32 btf_id(const struct btf *btf);
#endif