Merge branch 'bpf_iter-BTF_ID-at-build-time'

Yonghong Song says:

====================
Commit 5a2798ab32ba
("bpf: Add BTF_ID_LIST/BTF_ID/BTF_ID_UNUSED macros")
implemented a mechanism to compute btf_ids at kernel build
time which can simplify kernel implementation and reduce
runtime overhead by removing in-kernel btf_id calculation.

This patch set tried to use this mechanism to compute
btf_ids for bpf_skc_to_*() helpers and for btf_id_or_null ctx
arguments specified during bpf iterator registration.
Please see individual patch for details.

Changelogs:
  v1 -> v2:
    - v1 ([1]) is only for bpf_skc_to_*() helpers. This version
      expanded it to cover ctx btf_id_or_null arguments
    - abandoned the change of "extern u32 name[]" to
      "static u32 name[]" for BPF_ID_LIST local "name" definition.
      gcc 9 incurred a compilation error.

 [1]: https://lore.kernel.org/bpf/20200717184706.3476992-1-yhs@fb.com/T
====================

Signed-off-by: Alexei Starovoitov <ast@kernel.org>

2 files changed, 38 insertions, 7 deletions

diff --git a/include/linux/bpf.h b/include/linux/bpf.h
index adb16bdc5f0a..bae557ff2da8 100644
--- a/include/linux/bpf.h
+++ b/include/linux/bpf.h
@@ -668,6 +668,7 @@ struct bpf_jit_poke_descriptor {
 struct bpf_ctx_arg_aux {
 	u32 offset;
 	enum bpf_reg_type reg_type;
+	u32 btf_id;
 };
 
 struct bpf_prog_aux {
@@ -1541,7 +1542,6 @@ static inline bool bpf_map_is_dev_bound(struct bpf_map *map)
 
 struct bpf_map *bpf_map_offload_map_alloc(union bpf_attr *attr);
 void bpf_map_offload_map_free(struct bpf_map *map);
-void init_btf_sock_ids(struct btf *btf);
 #else
 static inline int bpf_prog_offload_init(struct bpf_prog *prog,
 					union bpf_attr *attr)
@@ -1567,9 +1567,6 @@ static inline struct bpf_map *bpf_map_offload_map_alloc(union bpf_attr *attr)
 static inline void bpf_map_offload_map_free(struct bpf_map *map)
 {
 }
-static inline void init_btf_sock_ids(struct btf *btf)
-{
-}
 #endif /* CONFIG_NET && CONFIG_BPF_SYSCALL */
 
 #if defined(CONFIG_BPF_STREAM_PARSER)
diff --git a/include/linux/btf_ids.h b/include/linux/btf_ids.h
index 1cdb56950ffe..4867d549e3c1 100644
--- a/include/linux/btf_ids.h
+++ b/include/linux/btf_ids.h
@@ -57,17 +57,20 @@ asm(							\
  * .zero 4
  *
  */
-#define __BTF_ID_LIST(name)				\
+#define __BTF_ID_LIST(name, scope)			\
 asm(							\
 ".pushsection " BTF_IDS_SECTION ",\"a\";       \n"	\
-".local " #name ";                             \n"	\
+"." #scope " " #name ";                        \n"	\
 #name ":;                                      \n"	\
 ".popsection;                                  \n");	\
 
 #define BTF_ID_LIST(name)				\
-__BTF_ID_LIST(name)					\
+__BTF_ID_LIST(name, local)				\
 extern u32 name[];
 
+#define BTF_ID_LIST_GLOBAL(name)			\
+__BTF_ID_LIST(name, globl)
+
 /*
  * The BTF_ID_UNUSED macro defines 4 zero bytes.
  * It's used when we want to define 'unused' entry
@@ -90,7 +93,38 @@ asm(							\
 #define BTF_ID_LIST(name) static u32 name[5];
 #define BTF_ID(prefix, name)
 #define BTF_ID_UNUSED
+#define BTF_ID_LIST_GLOBAL(name) u32 name[1];
 
 #endif /* CONFIG_DEBUG_INFO_BTF */
 
+#ifdef CONFIG_NET
+/* Define a list of socket types which can be the argument for
+ * skc_to_*_sock() helpers. All these sockets should have
+ * sock_common as the first argument in its memory layout.
+ */
+#define BTF_SOCK_TYPE_xxx \
+	BTF_SOCK_TYPE(BTF_SOCK_TYPE_INET, inet_sock)			\
+	BTF_SOCK_TYPE(BTF_SOCK_TYPE_INET_CONN, inet_connection_sock)	\
+	BTF_SOCK_TYPE(BTF_SOCK_TYPE_INET_REQ, inet_request_sock)	\
+	BTF_SOCK_TYPE(BTF_SOCK_TYPE_INET_TW, inet_timewait_sock)	\
+	BTF_SOCK_TYPE(BTF_SOCK_TYPE_REQ, request_sock)			\
+	BTF_SOCK_TYPE(BTF_SOCK_TYPE_SOCK, sock)				\
+	BTF_SOCK_TYPE(BTF_SOCK_TYPE_SOCK_COMMON, sock_common)		\
+	BTF_SOCK_TYPE(BTF_SOCK_TYPE_TCP, tcp_sock)			\
+	BTF_SOCK_TYPE(BTF_SOCK_TYPE_TCP_REQ, tcp_request_sock)		\
+	BTF_SOCK_TYPE(BTF_SOCK_TYPE_TCP_TW, tcp_timewait_sock)		\
+	BTF_SOCK_TYPE(BTF_SOCK_TYPE_TCP6, tcp6_sock)			\
+	BTF_SOCK_TYPE(BTF_SOCK_TYPE_UDP, udp_sock)			\
+	BTF_SOCK_TYPE(BTF_SOCK_TYPE_UDP6, udp6_sock)
+
+enum {
+#define BTF_SOCK_TYPE(name, str) name,
+BTF_SOCK_TYPE_xxx
+#undef BTF_SOCK_TYPE
+MAX_BTF_SOCK_TYPE,
+};
+
+extern u32 btf_sock_ids[];
+#endif
+
 #endif