bpf: treewide: Annotate BPF kfuncs in BTF

This commit marks kfuncs as such inside the .BTF_ids section. The upshot
of these annotations is that we'll be able to automatically generate
kfunc prototypes for downstream users. The process is as follows:

1. In source, use BTF_KFUNCS_START/END macro pair to mark kfuncs
2. During build, pahole injects into BTF a "bpf_kfunc" BTF_DECL_TAG for
   each function inside BTF_KFUNCS sets
3. At runtime, vmlinux or module BTF is made available in sysfs
4. At runtime, bpftool (or similar) can look at provided BTF and
   generate appropriate prototypes for functions with "bpf_kfunc" tag

To ensure future kfunc are similarly tagged, we now also return error
inside kfunc registration for untagged kfuncs. For vmlinux kfuncs,
we also WARN(), as initcall machinery does not handle errors.

Signed-off-by: Daniel Xu <dxu@dxuuu.xyz>
Acked-by: Benjamin Tissoires <bentiss@kernel.org>
Link: https://lore.kernel.org/r/e55150ceecbf0a5d961e608941165c0bee7bc943.1706491398.git.dxu@dxuuu.xyz
Signed-off-by: Alexei Starovoitov <ast@kernel.org>

12 files changed, 34 insertions, 34 deletions

diff --git a/net/bpf/test_run.c b/net/bpf/test_run.c
index dfd919374017..5535f9adc658 100644
--- a/net/bpf/test_run.c
+++ b/net/bpf/test_run.c
@@ -617,21 +617,21 @@ CFI_NOSEAL(bpf_kfunc_call_memb_release_dtor);
 
 __bpf_kfunc_end_defs();
 
-BTF_SET8_START(bpf_test_modify_return_ids)
+BTF_KFUNCS_START(bpf_test_modify_return_ids)
 BTF_ID_FLAGS(func, bpf_modify_return_test)
 BTF_ID_FLAGS(func, bpf_modify_return_test2)
 BTF_ID_FLAGS(func, bpf_fentry_test1, KF_SLEEPABLE)
-BTF_SET8_END(bpf_test_modify_return_ids)
+BTF_KFUNCS_END(bpf_test_modify_return_ids)
 
 static const struct btf_kfunc_id_set bpf_test_modify_return_set = {
 	.owner = THIS_MODULE,
 	.set   = &bpf_test_modify_return_ids,
 };
 
-BTF_SET8_START(test_sk_check_kfunc_ids)
+BTF_KFUNCS_START(test_sk_check_kfunc_ids)
 BTF_ID_FLAGS(func, bpf_kfunc_call_test_release, KF_RELEASE)
 BTF_ID_FLAGS(func, bpf_kfunc_call_memb_release, KF_RELEASE)
-BTF_SET8_END(test_sk_check_kfunc_ids)
+BTF_KFUNCS_END(test_sk_check_kfunc_ids)
 
 static void *bpf_test_init(const union bpf_attr *kattr, u32 user_size,
 			   u32 size, u32 headroom, u32 tailroom)
diff --git a/net/core/filter.c b/net/core/filter.c
index 358870408a51..524adf1fa6d0 100644
--- a/net/core/filter.c
+++ b/net/core/filter.c
@@ -11982,21 +11982,21 @@ int bpf_dynptr_from_skb_rdonly(struct sk_buff *skb, u64 flags,
 	return 0;
 }
 
-BTF_SET8_START(bpf_kfunc_check_set_skb)
+BTF_KFUNCS_START(bpf_kfunc_check_set_skb)
 BTF_ID_FLAGS(func, bpf_dynptr_from_skb)
-BTF_SET8_END(bpf_kfunc_check_set_skb)
+BTF_KFUNCS_END(bpf_kfunc_check_set_skb)
 
-BTF_SET8_START(bpf_kfunc_check_set_xdp)
+BTF_KFUNCS_START(bpf_kfunc_check_set_xdp)
 BTF_ID_FLAGS(func, bpf_dynptr_from_xdp)
-BTF_SET8_END(bpf_kfunc_check_set_xdp)
+BTF_KFUNCS_END(bpf_kfunc_check_set_xdp)
 
-BTF_SET8_START(bpf_kfunc_check_set_sock_addr)
+BTF_KFUNCS_START(bpf_kfunc_check_set_sock_addr)
 BTF_ID_FLAGS(func, bpf_sock_addr_set_sun_path)
-BTF_SET8_END(bpf_kfunc_check_set_sock_addr)
+BTF_KFUNCS_END(bpf_kfunc_check_set_sock_addr)
 
-BTF_SET8_START(bpf_kfunc_check_set_tcp_reqsk)
+BTF_KFUNCS_START(bpf_kfunc_check_set_tcp_reqsk)
 BTF_ID_FLAGS(func, bpf_sk_assign_tcp_reqsk, KF_TRUSTED_ARGS)
-BTF_SET8_END(bpf_kfunc_check_set_tcp_reqsk)
+BTF_KFUNCS_END(bpf_kfunc_check_set_tcp_reqsk)
 
 static const struct btf_kfunc_id_set bpf_kfunc_set_skb = {
 	.owner = THIS_MODULE,
@@ -12075,9 +12075,9 @@ __bpf_kfunc int bpf_sock_destroy(struct sock_common *sock)
 
 __bpf_kfunc_end_defs();
 
-BTF_SET8_START(bpf_sk_iter_kfunc_ids)
+BTF_KFUNCS_START(bpf_sk_iter_kfunc_ids)
 BTF_ID_FLAGS(func, bpf_sock_destroy, KF_TRUSTED_ARGS)
-BTF_SET8_END(bpf_sk_iter_kfunc_ids)
+BTF_KFUNCS_END(bpf_sk_iter_kfunc_ids)
 
 static int tracing_iter_filter(const struct bpf_prog *prog, u32 kfunc_id)
 {
diff --git a/net/core/xdp.c b/net/core/xdp.c
index 4869c1c2d8f3..034fb80f3fbe 100644
--- a/net/core/xdp.c
+++ b/net/core/xdp.c
@@ -771,11 +771,11 @@ __bpf_kfunc int bpf_xdp_metadata_rx_vlan_tag(const struct xdp_md *ctx,
 
 __bpf_kfunc_end_defs();
 
-BTF_SET8_START(xdp_metadata_kfunc_ids)
+BTF_KFUNCS_START(xdp_metadata_kfunc_ids)
 #define XDP_METADATA_KFUNC(_, __, name, ___) BTF_ID_FLAGS(func, name, KF_TRUSTED_ARGS)
 XDP_METADATA_KFUNC_xxx
 #undef XDP_METADATA_KFUNC
-BTF_SET8_END(xdp_metadata_kfunc_ids)
+BTF_KFUNCS_END(xdp_metadata_kfunc_ids)
 
 static const struct btf_kfunc_id_set xdp_metadata_kfunc_set = {
 	.owner = THIS_MODULE,
diff --git a/net/ipv4/bpf_tcp_ca.c b/net/ipv4/bpf_tcp_ca.c
index 834edc18463a..7f518ea5f4ac 100644
--- a/net/ipv4/bpf_tcp_ca.c
+++ b/net/ipv4/bpf_tcp_ca.c
@@ -201,13 +201,13 @@ bpf_tcp_ca_get_func_proto(enum bpf_func_id func_id,
 	}
 }
 
-BTF_SET8_START(bpf_tcp_ca_check_kfunc_ids)
+BTF_KFUNCS_START(bpf_tcp_ca_check_kfunc_ids)
 BTF_ID_FLAGS(func, tcp_reno_ssthresh)
 BTF_ID_FLAGS(func, tcp_reno_cong_avoid)
 BTF_ID_FLAGS(func, tcp_reno_undo_cwnd)
 BTF_ID_FLAGS(func, tcp_slow_start)
 BTF_ID_FLAGS(func, tcp_cong_avoid_ai)
-BTF_SET8_END(bpf_tcp_ca_check_kfunc_ids)
+BTF_KFUNCS_END(bpf_tcp_ca_check_kfunc_ids)
 
 static const struct btf_kfunc_id_set bpf_tcp_ca_kfunc_set = {
 	.owner = THIS_MODULE,
diff --git a/net/ipv4/fou_bpf.c b/net/ipv4/fou_bpf.c
index 4da03bf45c9b..06e5572f296f 100644
--- a/net/ipv4/fou_bpf.c
+++ b/net/ipv4/fou_bpf.c
@@ -100,10 +100,10 @@ __bpf_kfunc int bpf_skb_get_fou_encap(struct __sk_buff *skb_ctx,
 
 __bpf_kfunc_end_defs();
 
-BTF_SET8_START(fou_kfunc_set)
+BTF_KFUNCS_START(fou_kfunc_set)
 BTF_ID_FLAGS(func, bpf_skb_set_fou_encap)
 BTF_ID_FLAGS(func, bpf_skb_get_fou_encap)
-BTF_SET8_END(fou_kfunc_set)
+BTF_KFUNCS_END(fou_kfunc_set)
 
 static const struct btf_kfunc_id_set fou_bpf_kfunc_set = {
 	.owner = THIS_MODULE,
diff --git a/net/ipv4/tcp_bbr.c b/net/ipv4/tcp_bbr.c
index 22358032dd48..05dc2d05bc7c 100644
--- a/net/ipv4/tcp_bbr.c
+++ b/net/ipv4/tcp_bbr.c
@@ -1155,7 +1155,7 @@ static struct tcp_congestion_ops tcp_bbr_cong_ops __read_mostly = {
 	.set_state	= bbr_set_state,
 };
 
-BTF_SET8_START(tcp_bbr_check_kfunc_ids)
+BTF_KFUNCS_START(tcp_bbr_check_kfunc_ids)
 #ifdef CONFIG_X86
 #ifdef CONFIG_DYNAMIC_FTRACE
 BTF_ID_FLAGS(func, bbr_init)
@@ -1168,7 +1168,7 @@ BTF_ID_FLAGS(func, bbr_min_tso_segs)
 BTF_ID_FLAGS(func, bbr_set_state)
 #endif
 #endif
-BTF_SET8_END(tcp_bbr_check_kfunc_ids)
+BTF_KFUNCS_END(tcp_bbr_check_kfunc_ids)
 
 static const struct btf_kfunc_id_set tcp_bbr_kfunc_set = {
 	.owner = THIS_MODULE,
diff --git a/net/ipv4/tcp_cubic.c b/net/ipv4/tcp_cubic.c
index 0fd78ecb67e7..44869ea089e3 100644
--- a/net/ipv4/tcp_cubic.c
+++ b/net/ipv4/tcp_cubic.c
@@ -485,7 +485,7 @@ static struct tcp_congestion_ops cubictcp __read_mostly = {
 	.name		= "cubic",
 };
 
-BTF_SET8_START(tcp_cubic_check_kfunc_ids)
+BTF_KFUNCS_START(tcp_cubic_check_kfunc_ids)
 #ifdef CONFIG_X86
 #ifdef CONFIG_DYNAMIC_FTRACE
 BTF_ID_FLAGS(func, cubictcp_init)
@@ -496,7 +496,7 @@ BTF_ID_FLAGS(func, cubictcp_cwnd_event)
 BTF_ID_FLAGS(func, cubictcp_acked)
 #endif
 #endif
-BTF_SET8_END(tcp_cubic_check_kfunc_ids)
+BTF_KFUNCS_END(tcp_cubic_check_kfunc_ids)
 
 static const struct btf_kfunc_id_set tcp_cubic_kfunc_set = {
 	.owner = THIS_MODULE,
diff --git a/net/ipv4/tcp_dctcp.c b/net/ipv4/tcp_dctcp.c
index bb23bb5b387a..e33fbe4933e4 100644
--- a/net/ipv4/tcp_dctcp.c
+++ b/net/ipv4/tcp_dctcp.c
@@ -260,7 +260,7 @@ static struct tcp_congestion_ops dctcp_reno __read_mostly = {
 	.name		= "dctcp-reno",
 };
 
-BTF_SET8_START(tcp_dctcp_check_kfunc_ids)
+BTF_KFUNCS_START(tcp_dctcp_check_kfunc_ids)
 #ifdef CONFIG_X86
 #ifdef CONFIG_DYNAMIC_FTRACE
 BTF_ID_FLAGS(func, dctcp_init)
@@ -271,7 +271,7 @@ BTF_ID_FLAGS(func, dctcp_cwnd_undo)
 BTF_ID_FLAGS(func, dctcp_state)
 #endif
 #endif
-BTF_SET8_END(tcp_dctcp_check_kfunc_ids)
+BTF_KFUNCS_END(tcp_dctcp_check_kfunc_ids)
 
 static const struct btf_kfunc_id_set tcp_dctcp_kfunc_set = {
 	.owner = THIS_MODULE,
diff --git a/net/netfilter/nf_conntrack_bpf.c b/net/netfilter/nf_conntrack_bpf.c
index 475358ec8212..d2492d050fe6 100644
--- a/net/netfilter/nf_conntrack_bpf.c
+++ b/net/netfilter/nf_conntrack_bpf.c
@@ -467,7 +467,7 @@ __bpf_kfunc int bpf_ct_change_status(struct nf_conn *nfct, u32 status)
 
 __bpf_kfunc_end_defs();
 
-BTF_SET8_START(nf_ct_kfunc_set)
+BTF_KFUNCS_START(nf_ct_kfunc_set)
 BTF_ID_FLAGS(func, bpf_xdp_ct_alloc, KF_ACQUIRE | KF_RET_NULL)
 BTF_ID_FLAGS(func, bpf_xdp_ct_lookup, KF_ACQUIRE | KF_RET_NULL)
 BTF_ID_FLAGS(func, bpf_skb_ct_alloc, KF_ACQUIRE | KF_RET_NULL)
@@ -478,7 +478,7 @@ BTF_ID_FLAGS(func, bpf_ct_set_timeout, KF_TRUSTED_ARGS)
 BTF_ID_FLAGS(func, bpf_ct_change_timeout, KF_TRUSTED_ARGS)
 BTF_ID_FLAGS(func, bpf_ct_set_status, KF_TRUSTED_ARGS)
 BTF_ID_FLAGS(func, bpf_ct_change_status, KF_TRUSTED_ARGS)
-BTF_SET8_END(nf_ct_kfunc_set)
+BTF_KFUNCS_END(nf_ct_kfunc_set)
 
 static const struct btf_kfunc_id_set nf_conntrack_kfunc_set = {
 	.owner = THIS_MODULE,
diff --git a/net/netfilter/nf_nat_bpf.c b/net/netfilter/nf_nat_bpf.c
index 6e3b2f58855f..481be15609b1 100644
--- a/net/netfilter/nf_nat_bpf.c
+++ b/net/netfilter/nf_nat_bpf.c
@@ -54,9 +54,9 @@ __bpf_kfunc int bpf_ct_set_nat_info(struct nf_conn___init *nfct,
 
 __bpf_kfunc_end_defs();
 
-BTF_SET8_START(nf_nat_kfunc_set)
+BTF_KFUNCS_START(nf_nat_kfunc_set)
 BTF_ID_FLAGS(func, bpf_ct_set_nat_info, KF_TRUSTED_ARGS)
-BTF_SET8_END(nf_nat_kfunc_set)
+BTF_KFUNCS_END(nf_nat_kfunc_set)
 
 static const struct btf_kfunc_id_set nf_bpf_nat_kfunc_set = {
 	.owner = THIS_MODULE,
diff --git a/net/xfrm/xfrm_interface_bpf.c b/net/xfrm/xfrm_interface_bpf.c
index 7d5e920141e9..5ea15037ebd1 100644
--- a/net/xfrm/xfrm_interface_bpf.c
+++ b/net/xfrm/xfrm_interface_bpf.c
@@ -93,10 +93,10 @@ __bpf_kfunc int bpf_skb_set_xfrm_info(struct __sk_buff *skb_ctx, const struct bp
 
 __bpf_kfunc_end_defs();
 
-BTF_SET8_START(xfrm_ifc_kfunc_set)
+BTF_KFUNCS_START(xfrm_ifc_kfunc_set)
 BTF_ID_FLAGS(func, bpf_skb_get_xfrm_info)
 BTF_ID_FLAGS(func, bpf_skb_set_xfrm_info)
-BTF_SET8_END(xfrm_ifc_kfunc_set)
+BTF_KFUNCS_END(xfrm_ifc_kfunc_set)
 
 static const struct btf_kfunc_id_set xfrm_interface_kfunc_set = {
 	.owner = THIS_MODULE,
diff --git a/net/xfrm/xfrm_state_bpf.c b/net/xfrm/xfrm_state_bpf.c
index 9e20d4a377f7..2248eda741f8 100644
--- a/net/xfrm/xfrm_state_bpf.c
+++ b/net/xfrm/xfrm_state_bpf.c
@@ -117,10 +117,10 @@ __bpf_kfunc void bpf_xdp_xfrm_state_release(struct xfrm_state *x)
 
 __bpf_kfunc_end_defs();
 
-BTF_SET8_START(xfrm_state_kfunc_set)
+BTF_KFUNCS_START(xfrm_state_kfunc_set)
 BTF_ID_FLAGS(func, bpf_xdp_get_xfrm_state, KF_RET_NULL | KF_ACQUIRE)
 BTF_ID_FLAGS(func, bpf_xdp_xfrm_state_release, KF_RELEASE)
-BTF_SET8_END(xfrm_state_kfunc_set)
+BTF_KFUNCS_END(xfrm_state_kfunc_set)
 
 static const struct btf_kfunc_id_set xfrm_state_xdp_kfunc_set = {
 	.owner = THIS_MODULE,