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, 59 insertions, 0 deletions

diff --git a/include/net/af_ieee802154.h b/include/net/af_ieee802154.h
new file mode 100644
index 000000000..c16be82b9
--- /dev/null
+++ b/include/net/af_ieee802154.h
@@ -0,0 +1,59 @@
+/* SPDX-License-Identifier: GPL-2.0-only */
+/*
+ * IEEE 802.15.4 interface for userspace
+ *
+ * Copyright 2007, 2008 Siemens AG
+ *
+ * Written by:
+ * Sergey Lapin <slapin@ossfans.org>
+ * Dmitry Eremin-Solenikov <dbaryshkov@gmail.com>
+ */
+
+#ifndef _AF_IEEE802154_H
+#define _AF_IEEE802154_H
+
+#include <linux/socket.h> /* for sa_family_t */
+
+enum {
+	IEEE802154_ADDR_NONE = 0x0,
+	/* RESERVED = 0x01, */
+	IEEE802154_ADDR_SHORT = 0x2, /* 16-bit address + PANid */
+	IEEE802154_ADDR_LONG = 0x3, /* 64-bit address + PANid */
+};
+
+/* address length, octets */
+#define IEEE802154_ADDR_LEN	8
+
+struct ieee802154_addr_sa {
+	int addr_type;
+	u16 pan_id;
+	union {
+		u8 hwaddr[IEEE802154_ADDR_LEN];
+		u16 short_addr;
+	};
+};
+
+#define IEEE802154_PANID_BROADCAST	0xffff
+#define IEEE802154_ADDR_BROADCAST	0xffff
+#define IEEE802154_ADDR_UNDEF		0xfffe
+
+struct sockaddr_ieee802154 {
+	sa_family_t family; /* AF_IEEE802154 */
+	struct ieee802154_addr_sa addr;
+};
+
+/* get/setsockopt */
+#define SOL_IEEE802154	0
+
+#define WPAN_WANTACK		0
+#define WPAN_SECURITY		1
+#define WPAN_SECURITY_LEVEL	2
+#define WPAN_WANTLQI		3
+
+#define WPAN_SECURITY_DEFAULT	0
+#define WPAN_SECURITY_OFF	1
+#define WPAN_SECURITY_ON	2
+
+#define WPAN_SECURITY_LEVEL_DEFAULT	(-1)
+
+#endif