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, 319 insertions, 0 deletions

diff --git a/include/trace/events/handshake.h b/include/trace/events/handshake.h
new file mode 100644
index 000000000..bdd8a03cf
--- /dev/null
+++ b/include/trace/events/handshake.h
@@ -0,0 +1,319 @@
+/* SPDX-License-Identifier: GPL-2.0 */
+#undef TRACE_SYSTEM
+#define TRACE_SYSTEM handshake
+
+#if !defined(_TRACE_HANDSHAKE_H) || defined(TRACE_HEADER_MULTI_READ)
+#define _TRACE_HANDSHAKE_H
+
+#include <linux/net.h>
+#include <net/tls_prot.h>
+#include <linux/tracepoint.h>
+#include <trace/events/net_probe_common.h>
+
+#define TLS_RECORD_TYPE_LIST \
+	record_type(CHANGE_CIPHER_SPEC) \
+	record_type(ALERT) \
+	record_type(HANDSHAKE) \
+	record_type(DATA) \
+	record_type(HEARTBEAT) \
+	record_type(TLS12_CID) \
+	record_type_end(ACK)
+
+#undef record_type
+#undef record_type_end
+#define record_type(x)		TRACE_DEFINE_ENUM(TLS_RECORD_TYPE_##x);
+#define record_type_end(x)	TRACE_DEFINE_ENUM(TLS_RECORD_TYPE_##x);
+
+TLS_RECORD_TYPE_LIST
+
+#undef record_type
+#undef record_type_end
+#define record_type(x)		{ TLS_RECORD_TYPE_##x, #x },
+#define record_type_end(x)	{ TLS_RECORD_TYPE_##x, #x }
+
+#define show_tls_content_type(type) \
+	__print_symbolic(type, TLS_RECORD_TYPE_LIST)
+
+TRACE_DEFINE_ENUM(TLS_ALERT_LEVEL_WARNING);
+TRACE_DEFINE_ENUM(TLS_ALERT_LEVEL_FATAL);
+
+#define show_tls_alert_level(level) \
+	__print_symbolic(level, \
+		{ TLS_ALERT_LEVEL_WARNING,	"Warning" }, \
+		{ TLS_ALERT_LEVEL_FATAL,	"Fatal" })
+
+#define TLS_ALERT_DESCRIPTION_LIST \
+	alert_description(CLOSE_NOTIFY) \
+	alert_description(UNEXPECTED_MESSAGE) \
+	alert_description(BAD_RECORD_MAC) \
+	alert_description(RECORD_OVERFLOW) \
+	alert_description(HANDSHAKE_FAILURE) \
+	alert_description(BAD_CERTIFICATE) \
+	alert_description(UNSUPPORTED_CERTIFICATE) \
+	alert_description(CERTIFICATE_REVOKED) \
+	alert_description(CERTIFICATE_EXPIRED) \
+	alert_description(CERTIFICATE_UNKNOWN) \
+	alert_description(ILLEGAL_PARAMETER) \
+	alert_description(UNKNOWN_CA) \
+	alert_description(ACCESS_DENIED) \
+	alert_description(DECODE_ERROR) \
+	alert_description(DECRYPT_ERROR) \
+	alert_description(TOO_MANY_CIDS_REQUESTED) \
+	alert_description(PROTOCOL_VERSION) \
+	alert_description(INSUFFICIENT_SECURITY) \
+	alert_description(INTERNAL_ERROR) \
+	alert_description(INAPPROPRIATE_FALLBACK) \
+	alert_description(USER_CANCELED) \
+	alert_description(MISSING_EXTENSION) \
+	alert_description(UNSUPPORTED_EXTENSION) \
+	alert_description(UNRECOGNIZED_NAME) \
+	alert_description(BAD_CERTIFICATE_STATUS_RESPONSE) \
+	alert_description(UNKNOWN_PSK_IDENTITY) \
+	alert_description(CERTIFICATE_REQUIRED) \
+	alert_description_end(NO_APPLICATION_PROTOCOL)
+
+#undef alert_description
+#undef alert_description_end
+#define alert_description(x)		TRACE_DEFINE_ENUM(TLS_ALERT_DESC_##x);
+#define alert_description_end(x)	TRACE_DEFINE_ENUM(TLS_ALERT_DESC_##x);
+
+TLS_ALERT_DESCRIPTION_LIST
+
+#undef alert_description
+#undef alert_description_end
+#define alert_description(x)		{ TLS_ALERT_DESC_##x, #x },
+#define alert_description_end(x)	{ TLS_ALERT_DESC_##x, #x }
+
+#define show_tls_alert_description(desc) \
+	__print_symbolic(desc, TLS_ALERT_DESCRIPTION_LIST)
+
+DECLARE_EVENT_CLASS(handshake_event_class,
+	TP_PROTO(
+		const struct net *net,
+		const struct handshake_req *req,
+		const struct sock *sk
+	),
+	TP_ARGS(net, req, sk),
+	TP_STRUCT__entry(
+		__field(const void *, req)
+		__field(const void *, sk)
+		__field(unsigned int, netns_ino)
+	),
+	TP_fast_assign(
+		__entry->req = req;
+		__entry->sk = sk;
+		__entry->netns_ino = net->ns.inum;
+	),
+	TP_printk("req=%p sk=%p",
+		__entry->req, __entry->sk
+	)
+);
+#define DEFINE_HANDSHAKE_EVENT(name)				\
+	DEFINE_EVENT(handshake_event_class, name,		\
+		TP_PROTO(					\
+			const struct net *net,			\
+			const struct handshake_req *req,	\
+			const struct sock *sk			\
+		),						\
+		TP_ARGS(net, req, sk))
+
+DECLARE_EVENT_CLASS(handshake_fd_class,
+	TP_PROTO(
+		const struct net *net,
+		const struct handshake_req *req,
+		const struct sock *sk,
+		int fd
+	),
+	TP_ARGS(net, req, sk, fd),
+	TP_STRUCT__entry(
+		__field(const void *, req)
+		__field(const void *, sk)
+		__field(int, fd)
+		__field(unsigned int, netns_ino)
+	),
+	TP_fast_assign(
+		__entry->req = req;
+		__entry->sk = req->hr_sk;
+		__entry->fd = fd;
+		__entry->netns_ino = net->ns.inum;
+	),
+	TP_printk("req=%p sk=%p fd=%d",
+		__entry->req, __entry->sk, __entry->fd
+	)
+);
+#define DEFINE_HANDSHAKE_FD_EVENT(name)				\
+	DEFINE_EVENT(handshake_fd_class, name,			\
+		TP_PROTO(					\
+			const struct net *net,			\
+			const struct handshake_req *req,	\
+			const struct sock *sk,			\
+			int fd					\
+		),						\
+		TP_ARGS(net, req, sk, fd))
+
+DECLARE_EVENT_CLASS(handshake_error_class,
+	TP_PROTO(
+		const struct net *net,
+		const struct handshake_req *req,
+		const struct sock *sk,
+		int err
+	),
+	TP_ARGS(net, req, sk, err),
+	TP_STRUCT__entry(
+		__field(const void *, req)
+		__field(const void *, sk)
+		__field(int, err)
+		__field(unsigned int, netns_ino)
+	),
+	TP_fast_assign(
+		__entry->req = req;
+		__entry->sk = sk;
+		__entry->err = err;
+		__entry->netns_ino = net->ns.inum;
+	),
+	TP_printk("req=%p sk=%p err=%d",
+		__entry->req, __entry->sk, __entry->err
+	)
+);
+#define DEFINE_HANDSHAKE_ERROR(name)				\
+	DEFINE_EVENT(handshake_error_class, name,		\
+		TP_PROTO(					\
+			const struct net *net,			\
+			const struct handshake_req *req,	\
+			const struct sock *sk,			\
+			int err					\
+		),						\
+		TP_ARGS(net, req, sk, err))
+
+DECLARE_EVENT_CLASS(handshake_alert_class,
+	TP_PROTO(
+		const struct sock *sk,
+		unsigned char level,
+		unsigned char description
+	),
+	TP_ARGS(sk, level, description),
+	TP_STRUCT__entry(
+		/* sockaddr_in6 is always bigger than sockaddr_in */
+		__array(__u8, saddr, sizeof(struct sockaddr_in6))
+		__array(__u8, daddr, sizeof(struct sockaddr_in6))
+		__field(unsigned int, netns_ino)
+		__field(unsigned long, level)
+		__field(unsigned long, description)
+	),
+	TP_fast_assign(
+		const struct inet_sock *inet = inet_sk(sk);
+
+		memset(__entry->saddr, 0, sizeof(struct sockaddr_in6));
+		memset(__entry->daddr, 0, sizeof(struct sockaddr_in6));
+		TP_STORE_ADDR_PORTS(__entry, inet, sk);
+
+		__entry->netns_ino = sock_net(sk)->ns.inum;
+		__entry->level = level;
+		__entry->description = description;
+	),
+	TP_printk("src=%pISpc dest=%pISpc %s: %s",
+		__entry->saddr, __entry->daddr,
+		show_tls_alert_level(__entry->level),
+		show_tls_alert_description(__entry->description)
+	)
+);
+#define DEFINE_HANDSHAKE_ALERT(name)				\
+	DEFINE_EVENT(handshake_alert_class, name,		\
+		TP_PROTO(					\
+			const struct sock *sk,			\
+			unsigned char level,			\
+			unsigned char description		\
+		),						\
+		TP_ARGS(sk, level, description))
+
+
+/*
+ * Request lifetime events
+ */
+
+DEFINE_HANDSHAKE_EVENT(handshake_submit);
+DEFINE_HANDSHAKE_ERROR(handshake_submit_err);
+DEFINE_HANDSHAKE_EVENT(handshake_cancel);
+DEFINE_HANDSHAKE_EVENT(handshake_cancel_none);
+DEFINE_HANDSHAKE_EVENT(handshake_cancel_busy);
+DEFINE_HANDSHAKE_EVENT(handshake_destruct);
+
+
+TRACE_EVENT(handshake_complete,
+	TP_PROTO(
+		const struct net *net,
+		const struct handshake_req *req,
+		const struct sock *sk,
+		int status
+	),
+	TP_ARGS(net, req, sk, status),
+	TP_STRUCT__entry(
+		__field(const void *, req)
+		__field(const void *, sk)
+		__field(int, status)
+		__field(unsigned int, netns_ino)
+	),
+	TP_fast_assign(
+		__entry->req = req;
+		__entry->sk = sk;
+		__entry->status = status;
+		__entry->netns_ino = net->ns.inum;
+	),
+	TP_printk("req=%p sk=%p status=%d",
+		__entry->req, __entry->sk, __entry->status
+	)
+);
+
+/*
+ * Netlink events
+ */
+
+DEFINE_HANDSHAKE_ERROR(handshake_notify_err);
+DEFINE_HANDSHAKE_FD_EVENT(handshake_cmd_accept);
+DEFINE_HANDSHAKE_ERROR(handshake_cmd_accept_err);
+DEFINE_HANDSHAKE_FD_EVENT(handshake_cmd_done);
+DEFINE_HANDSHAKE_ERROR(handshake_cmd_done_err);
+
+/*
+ * TLS Record events
+ */
+
+TRACE_EVENT(tls_contenttype,
+	TP_PROTO(
+		const struct sock *sk,
+		unsigned char type
+	),
+	TP_ARGS(sk, type),
+	TP_STRUCT__entry(
+		/* sockaddr_in6 is always bigger than sockaddr_in */
+		__array(__u8, saddr, sizeof(struct sockaddr_in6))
+		__array(__u8, daddr, sizeof(struct sockaddr_in6))
+		__field(unsigned int, netns_ino)
+		__field(unsigned long, type)
+	),
+	TP_fast_assign(
+		const struct inet_sock *inet = inet_sk(sk);
+
+		memset(__entry->saddr, 0, sizeof(struct sockaddr_in6));
+		memset(__entry->daddr, 0, sizeof(struct sockaddr_in6));
+		TP_STORE_ADDR_PORTS(__entry, inet, sk);
+
+		__entry->netns_ino = sock_net(sk)->ns.inum;
+		__entry->type = type;
+	),
+	TP_printk("src=%pISpc dest=%pISpc %s",
+		__entry->saddr, __entry->daddr,
+		show_tls_content_type(__entry->type)
+	)
+);
+
+/*
+ * TLS Alert events
+ */
+
+DEFINE_HANDSHAKE_ALERT(tls_alert_send);
+DEFINE_HANDSHAKE_ALERT(tls_alert_recv);
+
+#endif /* _TRACE_HANDSHAKE_H */
+
+#include <trace/define_trace.h>