[PATCH bpf-next 10/15] bpf: Add bpf_btf_find_by_name_kind() helper.

[Alexei Starovoitov <alexei.starovoitov@gmail.com>]

From: Alexei Starovoitov <ast@kernel.org>

Add bpf_btf_find_by_name_kind() helper.

Signed-off-by: Alexei Starovoitov <ast@kernel.org>
---
 include/linux/bpf.h            |  1 +
 include/uapi/linux/bpf.h       |  8 ++++++
 kernel/bpf/btf.c               | 51 ++++++++++++++++++++++++++++++++++
 kernel/bpf/syscall.c           |  2 ++
 tools/include/uapi/linux/bpf.h |  8 ++++++
 5 files changed, 70 insertions(+)

diff --git a/include/linux/bpf.h b/include/linux/bpf.h
index 1aede7ceea5e..fe28ccb57f83 100644
--- a/include/linux/bpf.h
+++ b/include/linux/bpf.h
@@ -1970,6 +1970,7 @@ extern const struct bpf_func_proto bpf_get_socket_ptr_cookie_proto;
 extern const struct bpf_func_proto bpf_task_storage_get_proto;
 extern const struct bpf_func_proto bpf_task_storage_delete_proto;
 extern const struct bpf_func_proto bpf_for_each_map_elem_proto;
+extern const struct bpf_func_proto bpf_btf_find_by_name_kind_proto;
 
 const struct bpf_func_proto *bpf_tracing_func_proto(
 	enum bpf_func_id func_id, const struct bpf_prog *prog);
diff --git a/include/uapi/linux/bpf.h b/include/uapi/linux/bpf.h
index 068c23f278bc..47c4b21a51b6 100644
--- a/include/uapi/linux/bpf.h
+++ b/include/uapi/linux/bpf.h
@@ -4721,6 +4721,13 @@ union bpf_attr {
  * 		Execute bpf syscall with given arguments.
  * 	Return
  * 		A syscall result.
+ *
+ * long bpf_btf_find_by_name_kind(u32 btf_fd, char *name, u32 kind, u32 *attach_btf_obj_fd, int flags)
+ * 	Description
+ * 		Find given name with given type in BTF pointed to by btf_fd.
+ * 		If btf_fd is zero look for the name in vmlinux BTF and kernel module BTFs.
+ * 	Return
+ * 		Return btf_id and store module's BTF FD into attach_btf_obj_fd.
  */
 #define __BPF_FUNC_MAPPER(FN)		\
 	FN(unspec),			\
@@ -4889,6 +4896,7 @@ union bpf_attr {
 	FN(check_mtu),			\
 	FN(for_each_map_elem),		\
 	FN(sys_bpf),			\
+	FN(btf_find_by_name_kind),	\
 	/* */
 
 /* integer value in 'imm' field of BPF_CALL instruction selects which helper
diff --git a/kernel/bpf/btf.c b/kernel/bpf/btf.c
index fbf6c06a9d62..2f474739d9d3 100644
--- a/kernel/bpf/btf.c
+++ b/kernel/bpf/btf.c
@@ -6085,3 +6085,54 @@ struct module *btf_try_get_module(const struct btf *btf)
 
 	return res;
 }
+
+BPF_CALL_5(bpf_btf_find_by_name_kind, int, btf_fd, char *, name, u32, kind, int *, attach_btf_obj_fd, int, flags)
+{
+	struct btf *btf;
+	int ret;
+
+	if (flags)
+		return -EINVAL;
+
+	if (btf_fd)
+		btf = btf_get_by_fd(btf_fd);
+	else
+		btf = bpf_get_btf_vmlinux();
+	if (IS_ERR(btf))
+		return PTR_ERR(btf);
+
+	*attach_btf_obj_fd = 0;
+	ret = btf_find_by_name_kind(btf, name, kind);
+	if (!btf_fd && ret < 0) {
+		struct btf *mod_btf;
+		int id = btf->id;
+
+		spin_lock_bh(&btf_idr_lock);
+		idr_for_each_entry_continue(&btf_idr, mod_btf, id) {
+			if (!btf_is_kernel(btf))
+				continue;
+			ret = btf_find_by_name_kind(mod_btf, name, kind);
+			if (ret > 0)
+				break;
+		}
+		if (mod_btf)
+			btf_get(mod_btf);
+		spin_unlock_bh(&btf_idr_lock);
+		if (mod_btf)
+			*attach_btf_obj_fd = __btf_new_fd(mod_btf);
+	}
+	if (btf_fd)
+		btf_put(btf);
+	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_ANYTHING,
+	.arg2_type	= ARG_ANYTHING,
+	.arg3_type	= ARG_ANYTHING,
+	.arg4_type	= ARG_PTR_TO_INT,
+	.arg5_type	= ARG_ANYTHING,
+};
diff --git a/kernel/bpf/syscall.c b/kernel/bpf/syscall.c
index 7b51d56e420b..6d4d9925c0ec 100644
--- a/kernel/bpf/syscall.c
+++ b/kernel/bpf/syscall.c
@@ -4563,6 +4563,8 @@ 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 bpf_base_func_proto(func_id);
 	}
diff --git a/tools/include/uapi/linux/bpf.h b/tools/include/uapi/linux/bpf.h
index 068c23f278bc..47c4b21a51b6 100644
--- a/tools/include/uapi/linux/bpf.h
+++ b/tools/include/uapi/linux/bpf.h
@@ -4721,6 +4721,13 @@ union bpf_attr {
  * 		Execute bpf syscall with given arguments.
  * 	Return
  * 		A syscall result.
+ *
+ * long bpf_btf_find_by_name_kind(u32 btf_fd, char *name, u32 kind, u32 *attach_btf_obj_fd, int flags)
+ * 	Description
+ * 		Find given name with given type in BTF pointed to by btf_fd.
+ * 		If btf_fd is zero look for the name in vmlinux BTF and kernel module BTFs.
+ * 	Return
+ * 		Return btf_id and store module's BTF FD into attach_btf_obj_fd.
  */
 #define __BPF_FUNC_MAPPER(FN)		\
 	FN(unspec),			\
@@ -4889,6 +4896,7 @@ union bpf_attr {
 	FN(check_mtu),			\
 	FN(for_each_map_elem),		\
 	FN(sys_bpf),			\
+	FN(btf_find_by_name_kind),	\
 	/* */
 
 /* integer value in 'imm' field of BPF_CALL instruction selects which helper
-- 
2.30.2