kbuild: rust: keep Rust objects out of Clang LTO with inline helpersgrafted

Under `CONFIG_LTO_CLANG` + `CONFIG_RUST_INLINE_HELPERS`, one may hit
`objtool` errors such as:

    vmlinux.o: error: objtool: _R..._3Gsp4boot+0xd6a:
    can't find jump dest instruction at .text._R..._3Gsp4boot+0x1dfd

The reason is that in such builds, the Clang invocation that compiles
the combined Rust plus helpers bitcode emits LLVM bitcode (again) --
the final code generation happens in the linker's LTO step, which the
`-mllvm` trap options passed to Clang do not reach.

This, in turn, means that unreachable traps are missing, and the
impossible paths do not merely fallthrough to the next symbol, but past
the end of their own section, since LTO builds place each function in
its own section.

Thus filter `CC_FLAGS_LTO` out of the Clang invocation, so that it always
emits machine code directly, with the traps in place.

Assisted-by: LLM
Cc: Gary Guo <gary@garyguo.net>
Cc: Boqun Feng <boqun@kernel.org>
Cc: Alice Ryhl <aliceryhl@google.com>
Cc: Matthew Maurer <mmaurer@google.com>
Cc: Josh Poimboeuf <jpoimboe@kernel.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: stable@vger.kernel.org
Fixes: 3a2486cc1da5 ("kbuild: rust: provide an option to inline C helpers into Rust")
Acked-by: Gary Guo <gary@garyguo.net>
Link: https://patch.msgid.link/20260816133233.197500-2-ojeda@kernel.org
Signed-off-by: Miguel Ojeda <ojeda@kernel.org>

1 files changed, 312 insertions, 0 deletions

diff --git a/include/trace/events/sock.h b/include/trace/events/sock.h
new file mode 100644
index 000000000..b53104395
--- /dev/null
+++ b/include/trace/events/sock.h
@@ -0,0 +1,312 @@
+/* SPDX-License-Identifier: GPL-2.0 */
+#undef TRACE_SYSTEM
+#define TRACE_SYSTEM sock
+
+#if !defined(_TRACE_SOCK_H) || defined(TRACE_HEADER_MULTI_READ)
+#define _TRACE_SOCK_H
+
+#include <net/sock.h>
+#include <net/ipv6.h>
+#include <linux/tracepoint.h>
+#include <linux/ipv6.h>
+#include <linux/tcp.h>
+#include <trace/events/net_probe_common.h>
+
+#define family_names			\
+		EM(AF_INET)				\
+		EMe(AF_INET6)
+
+/* The protocol traced by inet_sock_set_state */
+#define inet_protocol_names		\
+		EM(IPPROTO_TCP)			\
+		EM(IPPROTO_SCTP)		\
+		EMe(IPPROTO_MPTCP)
+
+#define tcp_state_names			\
+		EM(TCP_ESTABLISHED)		\
+		EM(TCP_SYN_SENT)		\
+		EM(TCP_SYN_RECV)		\
+		EM(TCP_FIN_WAIT1)		\
+		EM(TCP_FIN_WAIT2)		\
+		EM(TCP_TIME_WAIT)		\
+		EM(TCP_CLOSE)			\
+		EM(TCP_CLOSE_WAIT)		\
+		EM(TCP_LAST_ACK)		\
+		EM(TCP_LISTEN)			\
+		EM(TCP_CLOSING)			\
+		EMe(TCP_NEW_SYN_RECV)
+
+#define skmem_kind_names			\
+		EM(SK_MEM_SEND)			\
+		EMe(SK_MEM_RECV)
+
+/* enums need to be exported to user space */
+#undef EM
+#undef EMe
+#define EM(a)       TRACE_DEFINE_ENUM(a);
+#define EMe(a)      TRACE_DEFINE_ENUM(a);
+
+family_names
+inet_protocol_names
+tcp_state_names
+skmem_kind_names
+
+#undef EM
+#undef EMe
+#define EM(a)       { a, #a },
+#define EMe(a)      { a, #a }
+
+#define show_family_name(val)			\
+	__print_symbolic(val, family_names)
+
+#define show_inet_protocol_name(val)    \
+	__print_symbolic(val, inet_protocol_names)
+
+#define show_tcp_state_name(val)        \
+	__print_symbolic(val, tcp_state_names)
+
+#define show_skmem_kind_names(val)	\
+	__print_symbolic(val, skmem_kind_names)
+
+TRACE_EVENT(sock_rcvqueue_full,
+
+	TP_PROTO(struct sock *sk, struct sk_buff *skb),
+
+	TP_ARGS(sk, skb),
+
+	TP_STRUCT__entry(
+		__field(int, rmem_alloc)
+		__field(unsigned int, truesize)
+		__field(int, sk_rcvbuf)
+	),
+
+	TP_fast_assign(
+		__entry->rmem_alloc = atomic_read(&sk->sk_rmem_alloc);
+		__entry->truesize   = skb->truesize;
+		__entry->sk_rcvbuf  = READ_ONCE(sk->sk_rcvbuf);
+	),
+
+	TP_printk("rmem_alloc=%d truesize=%u sk_rcvbuf=%d",
+		__entry->rmem_alloc, __entry->truesize, __entry->sk_rcvbuf)
+);
+
+TRACE_EVENT(sock_exceed_buf_limit,
+
+	TP_PROTO(struct sock *sk, struct proto *prot, long allocated, int kind),
+
+	TP_ARGS(sk, prot, allocated, kind),
+
+	TP_STRUCT__entry(
+		__array(char, name, 32)
+		__array(long, sysctl_mem, 3)
+		__field(long, allocated)
+		__field(int, sysctl_rmem)
+		__field(int, rmem_alloc)
+		__field(int, sysctl_wmem)
+		__field(int, wmem_alloc)
+		__field(int, wmem_queued)
+		__field(int, kind)
+	),
+
+	TP_fast_assign(
+		strscpy(__entry->name, prot->name, 32);
+		__entry->sysctl_mem[0] = READ_ONCE(prot->sysctl_mem[0]);
+		__entry->sysctl_mem[1] = READ_ONCE(prot->sysctl_mem[1]);
+		__entry->sysctl_mem[2] = READ_ONCE(prot->sysctl_mem[2]);
+		__entry->allocated = allocated;
+		__entry->sysctl_rmem = sk_get_rmem0(sk, prot);
+		__entry->rmem_alloc = atomic_read(&sk->sk_rmem_alloc);
+		__entry->sysctl_wmem = sk_get_wmem0(sk, prot);
+		__entry->wmem_alloc = refcount_read(&sk->sk_wmem_alloc);
+		__entry->wmem_queued = READ_ONCE(sk->sk_wmem_queued);
+		__entry->kind = kind;
+	),
+
+	TP_printk("proto:%s sysctl_mem=%ld,%ld,%ld allocated=%ld sysctl_rmem=%d rmem_alloc=%d sysctl_wmem=%d wmem_alloc=%d wmem_queued=%d kind=%s",
+		__entry->name,
+		__entry->sysctl_mem[0],
+		__entry->sysctl_mem[1],
+		__entry->sysctl_mem[2],
+		__entry->allocated,
+		__entry->sysctl_rmem,
+		__entry->rmem_alloc,
+		__entry->sysctl_wmem,
+		__entry->wmem_alloc,
+		__entry->wmem_queued,
+		show_skmem_kind_names(__entry->kind)
+	)
+);
+
+TRACE_EVENT(inet_sock_set_state,
+
+	TP_PROTO(const struct sock *sk, const int oldstate, const int newstate),
+
+	TP_ARGS(sk, oldstate, newstate),
+
+	TP_STRUCT__entry(
+		__field(const void *, skaddr)
+		__field(int, oldstate)
+		__field(int, newstate)
+		__field(__u16, sport)
+		__field(__u16, dport)
+		__field(__u16, family)
+		__field(__u16, protocol)
+		__array(__u8, saddr, 4)
+		__array(__u8, daddr, 4)
+		__array(__u8, saddr_v6, 16)
+		__array(__u8, daddr_v6, 16)
+	),
+
+	TP_fast_assign(
+		const struct inet_sock *inet = inet_sk(sk);
+		__be32 *p32;
+
+		__entry->skaddr = sk;
+		__entry->oldstate = oldstate;
+		__entry->newstate = newstate;
+
+		__entry->family = sk->sk_family;
+		__entry->protocol = sk->sk_protocol;
+		__entry->sport = ntohs(inet->inet_sport);
+		__entry->dport = ntohs(inet->inet_dport);
+
+		p32 = (__be32 *) __entry->saddr;
+		*p32 = inet->inet_saddr;
+
+		p32 = (__be32 *) __entry->daddr;
+		*p32 =  inet->inet_daddr;
+
+		TP_STORE_ADDRS(__entry, inet->inet_saddr, inet->inet_daddr,
+			       sk->sk_v6_rcv_saddr, sk->sk_v6_daddr);
+	),
+
+	TP_printk("family=%s protocol=%s sport=%hu dport=%hu saddr=%pI4 daddr=%pI4 saddrv6=%pI6c daddrv6=%pI6c oldstate=%s newstate=%s",
+			show_family_name(__entry->family),
+			show_inet_protocol_name(__entry->protocol),
+			__entry->sport, __entry->dport,
+			__entry->saddr, __entry->daddr,
+			__entry->saddr_v6, __entry->daddr_v6,
+			show_tcp_state_name(__entry->oldstate),
+			show_tcp_state_name(__entry->newstate))
+);
+
+TRACE_EVENT(inet_sk_error_report,
+
+	TP_PROTO(const struct sock *sk),
+
+	TP_ARGS(sk),
+
+	TP_STRUCT__entry(
+		__field(int, error)
+		__field(__u16, sport)
+		__field(__u16, dport)
+		__field(__u16, family)
+		__field(__u16, protocol)
+		__array(__u8, saddr, 4)
+		__array(__u8, daddr, 4)
+		__array(__u8, saddr_v6, 16)
+		__array(__u8, daddr_v6, 16)
+	),
+
+	TP_fast_assign(
+		const struct inet_sock *inet = inet_sk(sk);
+		__be32 *p32;
+
+		__entry->error = sk->sk_err;
+		__entry->family = sk->sk_family;
+		__entry->protocol = sk->sk_protocol;
+		__entry->sport = ntohs(inet->inet_sport);
+		__entry->dport = ntohs(inet->inet_dport);
+
+		p32 = (__be32 *) __entry->saddr;
+		*p32 = inet->inet_saddr;
+
+		p32 = (__be32 *) __entry->daddr;
+		*p32 =  inet->inet_daddr;
+
+		TP_STORE_ADDRS(__entry, inet->inet_saddr, inet->inet_daddr,
+			       sk->sk_v6_rcv_saddr, sk->sk_v6_daddr);
+	),
+
+	TP_printk("family=%s protocol=%s sport=%hu dport=%hu saddr=%pI4 daddr=%pI4 saddrv6=%pI6c daddrv6=%pI6c error=%d",
+		  show_family_name(__entry->family),
+		  show_inet_protocol_name(__entry->protocol),
+		  __entry->sport, __entry->dport,
+		  __entry->saddr, __entry->daddr,
+		  __entry->saddr_v6, __entry->daddr_v6,
+		  __entry->error)
+);
+
+TRACE_EVENT(sk_data_ready,
+
+	TP_PROTO(const struct sock *sk),
+
+	TP_ARGS(sk),
+
+	TP_STRUCT__entry(
+		__field(const void *, skaddr)
+		__field(__u16, family)
+		__field(__u16, protocol)
+		__field(unsigned long, ip)
+	),
+
+	TP_fast_assign(
+		__entry->skaddr = sk;
+		__entry->family = sk->sk_family;
+		__entry->protocol = sk->sk_protocol;
+		__entry->ip = _RET_IP_;
+	),
+
+	TP_printk("family=%u protocol=%u func=%ps",
+		  __entry->family, __entry->protocol, (void *)__entry->ip)
+);
+
+/*
+ * sock send/recv msg length
+ */
+DECLARE_EVENT_CLASS(sock_msg_length,
+
+	TP_PROTO(struct sock *sk, int ret, int flags),
+
+	TP_ARGS(sk, ret, flags),
+
+	TP_STRUCT__entry(
+		__field(void *, sk)
+		__field(__u16, family)
+		__field(__u16, protocol)
+		__field(int, ret)
+		__field(int, flags)
+	),
+
+	TP_fast_assign(
+		__entry->sk = sk;
+		__entry->family = sk->sk_family;
+		__entry->protocol = sk->sk_protocol;
+		__entry->ret = ret;
+		__entry->flags = flags;
+	),
+
+	TP_printk("sk address = %p, family = %s protocol = %s, length = %d, error = %d, flags = 0x%x",
+		  __entry->sk, show_family_name(__entry->family),
+		  show_inet_protocol_name(__entry->protocol),
+		  !(__entry->flags & MSG_PEEK) ?
+		  (__entry->ret > 0 ? __entry->ret : 0) : 0,
+		  __entry->ret < 0 ? __entry->ret : 0,
+		  __entry->flags)
+);
+
+DEFINE_EVENT(sock_msg_length, sock_send_length,
+	TP_PROTO(struct sock *sk, int ret, int flags),
+
+	TP_ARGS(sk, ret, flags)
+);
+
+DEFINE_EVENT(sock_msg_length, sock_recv_length,
+	TP_PROTO(struct sock *sk, int ret, int flags),
+
+	TP_ARGS(sk, ret, flags)
+);
+#endif /* _TRACE_SOCK_H */
+
+/* This part must be outside protection */
+#include <trace/define_trace.h>