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authorAlexei Starovoitov <ast@kernel.org>2021-05-13 17:36:11 -0700
committerDaniel Borkmann <daniel@iogearbox.net>2021-05-19 00:33:40 +0200
commit3d78417b60fba249cc555468cb72d96f5cde2964 (patch)
treec61b6a262c43b125b25c3601be7285f51df5a91f /kernel
parent387544bfa291a22383d60b40f887360e2b931ec6 (diff)
bpf: Add bpf_btf_find_by_name_kind() helper.
Add new helper: long bpf_btf_find_by_name_kind(char *name, int name_sz, u32 kind, int flags) Description Find BTF type with given name and kind in vmlinux BTF or in module's BTFs. Return Returns btf_id and btf_obj_fd in lower and upper 32 bits. It will be used by loader program to find btf_id to attach the program to and to find btf_ids of ksyms. Signed-off-by: Alexei Starovoitov <ast@kernel.org> Signed-off-by: Daniel Borkmann <daniel@iogearbox.net> Acked-by: Andrii Nakryiko <andrii@kernel.org> Link: https://lore.kernel.org/bpf/20210514003623.28033-10-alexei.starovoitov@gmail.com
Diffstat (limited to 'kernel')
-rw-r--r--kernel/bpf/btf.c62
-rw-r--r--kernel/bpf/syscall.c2
2 files changed, 64 insertions, 0 deletions
diff --git a/kernel/bpf/btf.c b/kernel/bpf/btf.c
index fbf6c06a9d62..85716327c375 100644
--- a/kernel/bpf/btf.c
+++ b/kernel/bpf/btf.c
@@ -6085,3 +6085,65 @@ struct module *btf_try_get_module(const struct btf *btf)
return res;
}
+
+BPF_CALL_4(bpf_btf_find_by_name_kind, char *, name, int, name_sz, u32, kind, int, flags)
+{
+ struct btf *btf;
+ long ret;
+
+ if (flags)
+ return -EINVAL;
+
+ if (name_sz <= 1 || name[name_sz - 1])
+ return -EINVAL;
+
+ btf = bpf_get_btf_vmlinux();
+ if (IS_ERR(btf))
+ return PTR_ERR(btf);
+
+ ret = btf_find_by_name_kind(btf, name, kind);
+ /* ret is never zero, since btf_find_by_name_kind returns
+ * positive btf_id or negative error.
+ */
+ if (ret < 0) {
+ struct btf *mod_btf;
+ int id;
+
+ /* If name is not found in vmlinux's BTF then search in module's BTFs */
+ spin_lock_bh(&btf_idr_lock);
+ idr_for_each_entry(&btf_idr, mod_btf, id) {
+ if (!btf_is_module(mod_btf))
+ continue;
+ /* linear search could be slow hence unlock/lock
+ * the IDR to avoiding holding it for too long
+ */
+ btf_get(mod_btf);
+ spin_unlock_bh(&btf_idr_lock);
+ ret = btf_find_by_name_kind(mod_btf, name, kind);
+ if (ret > 0) {
+ int btf_obj_fd;
+
+ btf_obj_fd = __btf_new_fd(mod_btf);
+ if (btf_obj_fd < 0) {
+ btf_put(mod_btf);
+ return btf_obj_fd;
+ }
+ return ret | (((u64)btf_obj_fd) << 32);
+ }
+ spin_lock_bh(&btf_idr_lock);
+ btf_put(mod_btf);
+ }
+ spin_unlock_bh(&btf_idr_lock);
+ }
+ return ret;
+}
+
+const struct bpf_func_proto bpf_btf_find_by_name_kind_proto = {
+ .func = bpf_btf_find_by_name_kind,
+ .gpl_only = false,
+ .ret_type = RET_INTEGER,
+ .arg1_type = ARG_PTR_TO_MEM,
+ .arg2_type = ARG_CONST_SIZE,
+ .arg3_type = ARG_ANYTHING,
+ .arg4_type = ARG_ANYTHING,
+};
diff --git a/kernel/bpf/syscall.c b/kernel/bpf/syscall.c
index da7dc2406470..f93ff2ebf96d 100644
--- a/kernel/bpf/syscall.c
+++ b/kernel/bpf/syscall.c
@@ -4584,6 +4584,8 @@ syscall_prog_func_proto(enum bpf_func_id func_id, const struct bpf_prog *prog)
switch (func_id) {
case BPF_FUNC_sys_bpf:
return &bpf_sys_bpf_proto;
+ case BPF_FUNC_btf_find_by_name_kind:
+ return &bpf_btf_find_by_name_kind_proto;
default:
return tracing_prog_func_proto(func_id, prog);
}