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, 202 insertions, 0 deletions

diff --git a/net/tls/trace.h b/net/tls/trace.h
new file mode 100644
index 000000000..2d8ce4ff3
--- /dev/null
+++ b/net/tls/trace.h
@@ -0,0 +1,202 @@
+/* SPDX-License-Identifier: (GPL-2.0-only OR BSD-2-Clause) */
+/* Copyright (C) 2019 Netronome Systems, Inc. */
+
+#undef TRACE_SYSTEM
+#define TRACE_SYSTEM tls
+
+#if !defined(_TLS_TRACE_H_) || defined(TRACE_HEADER_MULTI_READ)
+#define _TLS_TRACE_H_
+
+#include <linux/unaligned.h>
+#include <linux/tracepoint.h>
+
+struct sock;
+
+TRACE_EVENT(tls_device_offload_set,
+
+	TP_PROTO(struct sock *sk, int dir, u32 tcp_seq, u8 *rec_no, int ret),
+
+	TP_ARGS(sk, dir, tcp_seq, rec_no, ret),
+
+	TP_STRUCT__entry(
+		__field(	struct sock *,	sk		)
+		__field(	u64,		rec_no		)
+		__field(	int,		dir		)
+		__field(	u32,		tcp_seq		)
+		__field(	int,		ret		)
+	),
+
+	TP_fast_assign(
+		__entry->sk = sk;
+		__entry->rec_no = get_unaligned_be64(rec_no);
+		__entry->dir = dir;
+		__entry->tcp_seq = tcp_seq;
+		__entry->ret = ret;
+	),
+
+	TP_printk(
+		"sk=%p direction=%d tcp_seq=%u rec_no=%llu ret=%d",
+		__entry->sk, __entry->dir, __entry->tcp_seq, __entry->rec_no,
+		__entry->ret
+	)
+);
+
+TRACE_EVENT(tls_device_decrypted,
+
+	TP_PROTO(struct sock *sk, u32 tcp_seq, u8 *rec_no, u32 rec_len,
+		 bool encrypted, bool decrypted),
+
+	TP_ARGS(sk, tcp_seq, rec_no, rec_len, encrypted, decrypted),
+
+	TP_STRUCT__entry(
+		__field(	struct sock *,	sk		)
+		__field(	u64,		rec_no		)
+		__field(	u32,		tcp_seq		)
+		__field(	u32,		rec_len		)
+		__field(	bool,		encrypted	)
+		__field(	bool,		decrypted	)
+	),
+
+	TP_fast_assign(
+		__entry->sk = sk;
+		__entry->rec_no = get_unaligned_be64(rec_no);
+		__entry->tcp_seq = tcp_seq;
+		__entry->rec_len = rec_len;
+		__entry->encrypted = encrypted;
+		__entry->decrypted = decrypted;
+	),
+
+	TP_printk(
+		"sk=%p tcp_seq=%u rec_no=%llu len=%u encrypted=%d decrypted=%d",
+		__entry->sk, __entry->tcp_seq,
+		__entry->rec_no, __entry->rec_len,
+		__entry->encrypted, __entry->decrypted
+	)
+);
+
+TRACE_EVENT(tls_device_rx_resync_send,
+
+	TP_PROTO(struct sock *sk, u32 tcp_seq, u8 *rec_no, int sync_type),
+
+	TP_ARGS(sk, tcp_seq, rec_no, sync_type),
+
+	TP_STRUCT__entry(
+		__field(	struct sock *,	sk		)
+		__field(	u64,		rec_no		)
+		__field(	u32,		tcp_seq		)
+		__field(	int,		sync_type	)
+	),
+
+	TP_fast_assign(
+		__entry->sk = sk;
+		__entry->rec_no = get_unaligned_be64(rec_no);
+		__entry->tcp_seq = tcp_seq;
+		__entry->sync_type = sync_type;
+	),
+
+	TP_printk(
+		"sk=%p tcp_seq=%u rec_no=%llu sync_type=%d",
+		__entry->sk, __entry->tcp_seq, __entry->rec_no,
+		__entry->sync_type
+	)
+);
+
+TRACE_EVENT(tls_device_rx_resync_nh_schedule,
+
+	TP_PROTO(struct sock *sk),
+
+	TP_ARGS(sk),
+
+	TP_STRUCT__entry(
+		__field(	struct sock *,	sk		)
+	),
+
+	TP_fast_assign(
+		__entry->sk = sk;
+	),
+
+	TP_printk(
+		"sk=%p", __entry->sk
+	)
+);
+
+TRACE_EVENT(tls_device_rx_resync_nh_delay,
+
+	TP_PROTO(struct sock *sk, u32 sock_data, u32 rec_len),
+
+	TP_ARGS(sk, sock_data, rec_len),
+
+	TP_STRUCT__entry(
+		__field(	struct sock *,	sk		)
+		__field(	u32,		sock_data	)
+		__field(	u32,		rec_len		)
+	),
+
+	TP_fast_assign(
+		__entry->sk = sk;
+		__entry->sock_data = sock_data;
+		__entry->rec_len = rec_len;
+	),
+
+	TP_printk(
+		"sk=%p sock_data=%u rec_len=%u",
+		__entry->sk, __entry->sock_data, __entry->rec_len
+	)
+);
+
+TRACE_EVENT(tls_device_tx_resync_req,
+
+	TP_PROTO(struct sock *sk, u32 tcp_seq, u32 exp_tcp_seq),
+
+	TP_ARGS(sk, tcp_seq, exp_tcp_seq),
+
+	TP_STRUCT__entry(
+		__field(	struct sock *,	sk		)
+		__field(	u32,		tcp_seq		)
+		__field(	u32,		exp_tcp_seq	)
+	),
+
+	TP_fast_assign(
+		__entry->sk = sk;
+		__entry->tcp_seq = tcp_seq;
+		__entry->exp_tcp_seq = exp_tcp_seq;
+	),
+
+	TP_printk(
+		"sk=%p tcp_seq=%u exp_tcp_seq=%u",
+		__entry->sk, __entry->tcp_seq, __entry->exp_tcp_seq
+	)
+);
+
+TRACE_EVENT(tls_device_tx_resync_send,
+
+	TP_PROTO(struct sock *sk, u32 tcp_seq, u8 *rec_no),
+
+	TP_ARGS(sk, tcp_seq, rec_no),
+
+	TP_STRUCT__entry(
+		__field(	struct sock *,	sk		)
+		__field(	u64,		rec_no		)
+		__field(	u32,		tcp_seq		)
+	),
+
+	TP_fast_assign(
+		__entry->sk = sk;
+		__entry->rec_no = get_unaligned_be64(rec_no);
+		__entry->tcp_seq = tcp_seq;
+	),
+
+	TP_printk(
+		"sk=%p tcp_seq=%u rec_no=%llu",
+		__entry->sk, __entry->tcp_seq, __entry->rec_no
+	)
+);
+
+#endif /* _TLS_TRACE_H_ */
+
+#undef TRACE_INCLUDE_PATH
+#define TRACE_INCLUDE_PATH .
+#undef TRACE_INCLUDE_FILE
+#define TRACE_INCLUDE_FILE trace
+
+#include <trace/define_trace.h>