From 5febf432df1cfa5b25d99b54c32103fafbdd0eb9 Mon Sep 17 00:00:00 2001 From: Miguel Ojeda Date: Sun, 16 Aug 2026 15:32:33 +0200 Subject: kbuild: rust: keep Rust objects out of Clang LTO with inline helpers 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 Cc: Boqun Feng Cc: Alice Ryhl Cc: Matthew Maurer Cc: Josh Poimboeuf Cc: Peter Zijlstra Cc: stable@vger.kernel.org Fixes: 3a2486cc1da5 ("kbuild: rust: provide an option to inline C helpers into Rust") Acked-by: Gary Guo Link: https://patch.msgid.link/20260816133233.197500-2-ojeda@kernel.org Signed-off-by: Miguel Ojeda --- include/asm-generic/int-ll64.h | 47 ++++++++++++++++++++++++++++++++++++++++++ 1 file changed, 47 insertions(+) create mode 100644 include/asm-generic/int-ll64.h (limited to 'include/asm-generic/int-ll64.h') diff --git a/include/asm-generic/int-ll64.h b/include/asm-generic/int-ll64.h new file mode 100644 index 000000000..a248545f1 --- /dev/null +++ b/include/asm-generic/int-ll64.h @@ -0,0 +1,47 @@ +/* SPDX-License-Identifier: GPL-2.0 */ +/* + * asm-generic/int-ll64.h + * + * Integer declarations for architectures which use "long long" + * for 64-bit types. + */ +#ifndef _ASM_GENERIC_INT_LL64_H +#define _ASM_GENERIC_INT_LL64_H + +#include + + +#ifndef __ASSEMBLY__ + +typedef __s8 s8; +typedef __u8 u8; +typedef __s16 s16; +typedef __u16 u16; +typedef __s32 s32; +typedef __u32 u32; +typedef __s64 s64; +typedef __u64 u64; + +#define S8_C(x) x +#define U8_C(x) x ## U +#define S16_C(x) x +#define U16_C(x) x ## U +#define S32_C(x) x +#define U32_C(x) x ## U +#define S64_C(x) x ## LL +#define U64_C(x) x ## ULL + +#else /* __ASSEMBLY__ */ + +#define S8_C(x) x +#define U8_C(x) x +#define S16_C(x) x +#define U16_C(x) x +#define S32_C(x) x +#define U32_C(x) x +#define S64_C(x) x +#define U64_C(x) x + +#endif /* __ASSEMBLY__ */ + +#endif /* _ASM_GENERIC_INT_LL64_H */ -- cgit v1.3.1