bpf, sockmap: Introduce tracing capability for sockmap

Sockmap has the same high-performance forwarding capability as XDP, but
operates at Layer 7.

Introduce tracing capability for sockmap, similar to XDP, to trace the
execution results of BPF programs without modifying the programs
themselves, similar to the existing trace_xdp_redirect{_map}.

It is crucial for debugging BPF programs, especially in production
environments.

Additionally, a header file was added to bpf_trace.h to automatically
generate tracepoints.

Test results:
$ echo "1" > /sys/kernel/tracing/events/sockmap/enable

skb:
sockmap_redirect: sk=00000000d3266a8d, type=skb, family=2, protocol=6, \
prog_id=73, length=256, action=PASS

msg:
sockmap_redirect: sk=00000000528c7614, type=msg, family=2, protocol=6, \
prog_id=185, length=5, action=REDIRECT

tls:
sockmap_redirect: sk=00000000d04d2224, type=skb, family=2, protocol=6, \
prog_id=143, length=35, action=PASS

strparser:
sockmap_skb_strp_parse: sk=00000000ecab0b30, family=2, protocol=6, \
prog_id=170, size=5

Signed-off-by: Jiayuan Chen <[email protected]>

Author: mrpre

MAINTAINERS

@@ -4420,6 +4420,7 @@ L:	[email protected]
 L:	[email protected]
 S:	Maintained
 F:	include/linux/skmsg.h
+F:	include/trace/events/sockmap.h
 F:	net/core/skmsg.c
 F:	net/core/sock_map.c
 F:	net/ipv4/tcp_bpf.c

include/linux/bpf_trace.h

@@ -3,5 +3,5 @@
 #define __LINUX_BPF_TRACE_H__
 
 #include <trace/events/xdp.h>
-
+#include <trace/events/sockmap.h>
 #endif /* __LINUX_BPF_TRACE_H__ */

include/trace/events/sockmap.h

@@ -0,0 +1,89 @@
+/* SPDX-License-Identifier: GPL-2.0 */
+#undef TRACE_SYSTEM
+#define TRACE_SYSTEM sockmap
+
+#if !defined(_TRACE_SOCKMAP_H) || defined(TRACE_HEADER_MULTI_READ)
+#define _TRACE_SOCKMAP_H
+
+#include <linux/filter.h>
+#include <linux/tracepoint.h>
+#include <linux/bpf.h>
+#include <linux/skmsg.h>
+
+TRACE_DEFINE_ENUM(__SK_DROP);
+TRACE_DEFINE_ENUM(__SK_PASS);
+TRACE_DEFINE_ENUM(__SK_REDIRECT);
+TRACE_DEFINE_ENUM(__SK_NONE);
+
+#define show_act(x) \
+	__print_symbolic(x, \
+		{ __SK_DROP,		"DROP" }, \
+		{ __SK_PASS,		"PASS" }, \
+		{ __SK_REDIRECT,	"REDIRECT" }, \
+		{ __SK_NONE,		"NONE" })
+
+#define trace_sockmap_skmsg_redirect(sk, prog, msg, act)	\
+	trace_sockmap_redirect((sk), "msg", (prog), (msg)->sg.size, (act))
+
+#define trace_sockmap_skb_redirect(sk, prog, skb, act)		\
+	trace_sockmap_redirect((sk), "skb", (prog), (skb)->len, (act))
+
+TRACE_EVENT(sockmap_redirect,
+	    TP_PROTO(const struct sock *sk, const char *type,
+		     const struct bpf_prog *prog, int length, int act),
+	    TP_ARGS(sk, type, prog, length, act),
+
+	TP_STRUCT__entry(
+		__field(const void *, sk)
+		__field(const char *, type)
+		__field(__u16, family)
+		__field(__u16, protocol)
+		__field(int, prog_id)
+		__field(int, length)
+		__field(int, act)
+	),
+
+	TP_fast_assign(
+		__entry->sk		= sk;
+		__entry->type		= type;
+		__entry->family		= sk->sk_family;
+		__entry->protocol	= sk->sk_protocol;
+		__entry->prog_id	= prog->aux->id;
+		__entry->length		= length;
+		__entry->act		= act;
+	),
+
+	TP_printk("sk=%p, type=%s, family=%d, protocol=%d, prog_id=%d, length=%d, action=%s",
+		  __entry->sk, __entry->type, __entry->family, __entry->protocol,
+		  __entry->prog_id, __entry->length,
+		  show_act(__entry->act))
+);
+
+TRACE_EVENT(sockmap_skb_strp_parse,
+	    TP_PROTO(const struct sock *sk, const struct bpf_prog *prog,
+		     int size),
+	    TP_ARGS(sk, prog, size),
+
+	TP_STRUCT__entry(
+		__field(const void *, sk)
+		__field(__u16, family)
+		__field(__u16, protocol)
+		__field(int, prog_id)
+		__field(int, size)
+	),
+
+	TP_fast_assign(
+		__entry->sk		= sk;
+		__entry->family		= sk->sk_family;
+		__entry->protocol	= sk->sk_protocol;
+		__entry->prog_id	= prog->aux->id;
+		__entry->size		= size;
+	),
+
+	TP_printk("sk=%p, family=%d, protocol=%d, prog_id=%d, size=%d",
+		  __entry->sk, __entry->family, __entry->protocol,
+		  __entry->prog_id, __entry->size)
+);
+#endif /* _TRACE_SOCKMAP_H */
+
+#include <trace/define_trace.h>

net/core/skmsg.c

@@ -9,6 +9,7 @@
 #include <net/tcp.h>
 #include <net/tls.h>
 #include <trace/events/sock.h>
+#include <trace/events/sockmap.h>
 
 static bool sk_msg_try_coalesce_ok(struct sk_msg *msg, int elem_first_coalesce)
 {
@@ -904,6 +905,7 @@ int sk_psock_msg_verdict(struct sock *sk, struct sk_psock *psock,
 		sock_hold(psock->sk_redir);
 	}
 out:
+	trace_sockmap_skmsg_redirect(sk, prog, msg, ret);
 	rcu_read_unlock();
 	return ret;
 }
@@ -975,6 +977,7 @@ int sk_psock_tls_strp_read(struct sk_psock *psock, struct sk_buff *skb)
 		ret = bpf_prog_run_pin_on_cpu(prog, skb);
 		ret = sk_psock_map_verd(ret, skb_bpf_redirect_fetch(skb));
 		skb->sk = NULL;
+		trace_sockmap_skb_redirect(psock->sk, prog, skb, ret);
 	}
 	sk_psock_tls_verdict_apply(skb, psock, ret);
 	rcu_read_unlock();
@@ -1084,6 +1087,7 @@ static void sk_psock_strp_read(struct strparser *strp, struct sk_buff *skb)
 		skb_bpf_set_strparser(skb);
 		ret = sk_psock_map_verd(ret, skb_bpf_redirect_fetch(skb));
 		skb->sk = NULL;
+		trace_sockmap_skb_redirect(sk, prog, skb, ret);
 	}
 	sk_psock_verdict_apply(psock, skb, ret);
 out:
@@ -1107,6 +1111,7 @@ static int sk_psock_strp_parse(struct strparser *strp, struct sk_buff *skb)
 		skb->sk = psock->sk;
 		ret = bpf_prog_run_pin_on_cpu(prog, skb);
 		skb->sk = NULL;
+		trace_sockmap_skb_strp_parse(psock->sk, prog, ret);
 	}
 	rcu_read_unlock();
 	return ret;
@@ -1211,6 +1216,7 @@ static int sk_psock_verdict_recv(struct sock *sk, struct sk_buff *skb)
 		skb_bpf_redirect_clear(skb);
 		ret = bpf_prog_run_pin_on_cpu(prog, skb);
 		ret = sk_psock_map_verd(ret, skb_bpf_redirect_fetch(skb));
+		trace_sockmap_skb_redirect(psock->sk, prog, skb, ret);
 	}
 	ret = sk_psock_verdict_apply(psock, skb, ret);
 	if (ret < 0)