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>

5 files changed, 23 insertions, 48 deletions

diff --git a/net/core/filter.c b/net/core/filter.c
index 2bd129b5ae74..654c346b7d91 100644
--- a/net/core/filter.c
+++ b/net/core/filter.c
@@ -9421,52 +9421,13 @@ void bpf_prog_change_xdp(struct bpf_prog *prev_prog, struct bpf_prog *prog)
 	bpf_dispatcher_change_prog(BPF_DISPATCHER_PTR(xdp), prev_prog, prog);
 }
 
-/* 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,
+#ifdef CONFIG_DEBUG_INFO_BTF
+BTF_ID_LIST_GLOBAL(btf_sock_ids)
+#define BTF_SOCK_TYPE(name, type) BTF_ID(struct, type)
 BTF_SOCK_TYPE_xxx
 #undef BTF_SOCK_TYPE
-MAX_BTF_SOCK_TYPE,
-};
-
-static int btf_sock_ids[MAX_BTF_SOCK_TYPE];
-
-#ifdef CONFIG_BPF_SYSCALL
-static const char *bpf_sock_types[] = {
-#define BTF_SOCK_TYPE(name, str) str,
-BTF_SOCK_TYPE_xxx
-#undef BTF_SOCK_TYPE
-};
-
-void init_btf_sock_ids(struct btf *btf)
-{
-	int i, btf_id;
-
-	for (i = 0; i < MAX_BTF_SOCK_TYPE; i++) {
-		btf_id = btf_find_by_name_kind(btf, bpf_sock_types[i],
-					       BTF_KIND_STRUCT);
-		if (btf_id > 0)
-			btf_sock_ids[i] = btf_id;
-	}
-}
+#else
+u32 btf_sock_ids[MAX_BTF_SOCK_TYPE];
 #endif
 
 static bool check_arg_btf_id(u32 btf_id, u32 arg)
diff --git a/net/ipv4/tcp_ipv4.c b/net/ipv4/tcp_ipv4.c
index 116c11a0aaed..a7f1b41482f8 100644
--- a/net/ipv4/tcp_ipv4.c
+++ b/net/ipv4/tcp_ipv4.c
@@ -76,6 +76,7 @@
 #include <linux/proc_fs.h>
 #include <linux/seq_file.h>
 #include <linux/inetdevice.h>
+#include <linux/btf_ids.h>
 
 #include <crypto/hash.h>
 #include <linux/scatterlist.h>
@@ -2954,7 +2955,7 @@ static void bpf_iter_fini_tcp(void *priv_data)
 	bpf_iter_fini_seq_net(priv_data);
 }
 
-static const struct bpf_iter_reg tcp_reg_info = {
+static struct bpf_iter_reg tcp_reg_info = {
 	.target			= "tcp",
 	.seq_ops		= &bpf_iter_tcp_seq_ops,
 	.init_seq_private	= bpf_iter_init_tcp,
@@ -2969,6 +2970,7 @@ static const struct bpf_iter_reg tcp_reg_info = {
 
 static void __init bpf_iter_register(void)
 {
+	tcp_reg_info.ctx_arg_info[0].btf_id = btf_sock_ids[BTF_SOCK_TYPE_SOCK_COMMON];
 	if (bpf_iter_reg_target(&tcp_reg_info))
 		pr_warn("Warning: could not register bpf iterator tcp\n");
 }
diff --git a/net/ipv4/udp.c b/net/ipv4/udp.c
index b738c63d7a77..b5231ab350e0 100644
--- a/net/ipv4/udp.c
+++ b/net/ipv4/udp.c
@@ -106,6 +106,7 @@
 #include <net/xfrm.h>
 #include <trace/events/udp.h>
 #include <linux/static_key.h>
+#include <linux/btf_ids.h>
 #include <trace/events/skb.h>
 #include <net/busy_poll.h>
 #include "udp_impl.h"
@@ -3232,7 +3233,7 @@ static void bpf_iter_fini_udp(void *priv_data)
 	bpf_iter_fini_seq_net(priv_data);
 }
 
-static const struct bpf_iter_reg udp_reg_info = {
+static struct bpf_iter_reg udp_reg_info = {
 	.target			= "udp",
 	.seq_ops		= &bpf_iter_udp_seq_ops,
 	.init_seq_private	= bpf_iter_init_udp,
@@ -3247,6 +3248,7 @@ static const struct bpf_iter_reg udp_reg_info = {
 
 static void __init bpf_iter_register(void)
 {
+	udp_reg_info.ctx_arg_info[0].btf_id = btf_sock_ids[BTF_SOCK_TYPE_UDP];
 	if (bpf_iter_reg_target(&udp_reg_info))
 		pr_warn("Warning: could not register bpf iterator udp\n");
 }
diff --git a/net/ipv6/route.c b/net/ipv6/route.c
index 427b81cbc164..33f5efbad0a9 100644
--- a/net/ipv6/route.c
+++ b/net/ipv6/route.c
@@ -61,6 +61,7 @@
 #include <net/l3mdev.h>
 #include <net/ip.h>
 #include <linux/uaccess.h>
+#include <linux/btf_ids.h>
 
 #ifdef CONFIG_SYSCTL
 #include <linux/sysctl.h>
@@ -6423,7 +6424,10 @@ void __init ip6_route_init_special_entries(void)
 #if defined(CONFIG_BPF_SYSCALL) && defined(CONFIG_PROC_FS)
 DEFINE_BPF_ITER_FUNC(ipv6_route, struct bpf_iter_meta *meta, struct fib6_info *rt)
 
-static const struct bpf_iter_reg ipv6_route_reg_info = {
+BTF_ID_LIST(btf_fib6_info_id)
+BTF_ID(struct, fib6_info)
+
+static struct bpf_iter_reg ipv6_route_reg_info = {
 	.target			= "ipv6_route",
 	.seq_ops		= &ipv6_route_seq_ops,
 	.init_seq_private	= bpf_iter_init_seq_net,
@@ -6438,6 +6442,7 @@ static const struct bpf_iter_reg ipv6_route_reg_info = {
 
 static int __init bpf_iter_register(void)
 {
+	ipv6_route_reg_info.ctx_arg_info[0].btf_id = *btf_fib6_info_id;
 	return bpf_iter_reg_target(&ipv6_route_reg_info);
 }
 
diff --git a/net/netlink/af_netlink.c b/net/netlink/af_netlink.c
index 4f2c3b14ddbf..3cd58f0c2de4 100644
--- a/net/netlink/af_netlink.c
+++ b/net/netlink/af_netlink.c
@@ -60,6 +60,7 @@
 #include <linux/genetlink.h>
 #include <linux/net_namespace.h>
 #include <linux/nospec.h>
+#include <linux/btf_ids.h>
 
 #include <net/net_namespace.h>
 #include <net/netns/generic.h>
@@ -2803,7 +2804,10 @@ static const struct rhashtable_params netlink_rhashtable_params = {
 };
 
 #if defined(CONFIG_BPF_SYSCALL) && defined(CONFIG_PROC_FS)
-static const struct bpf_iter_reg netlink_reg_info = {
+BTF_ID_LIST(btf_netlink_sock_id)
+BTF_ID(struct, netlink_sock)
+
+static struct bpf_iter_reg netlink_reg_info = {
 	.target			= "netlink",
 	.seq_ops		= &netlink_seq_ops,
 	.init_seq_private	= bpf_iter_init_seq_net,
@@ -2818,6 +2822,7 @@ static const struct bpf_iter_reg netlink_reg_info = {
 
 static int __init bpf_iter_register(void)
 {
+	netlink_reg_info.ctx_arg_info[0].btf_id = *btf_netlink_sock_id;
 	return bpf_iter_reg_target(&netlink_reg_info);
 }
 #endif