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/video.h | 136 ++++++++++++++++++++++++++++++++++++++++++++ 1 file changed, 136 insertions(+) create mode 100644 include/asm-generic/video.h (limited to 'include/asm-generic/video.h') diff --git a/include/asm-generic/video.h b/include/asm-generic/video.h new file mode 100644 index 000000000..b1da2309d --- /dev/null +++ b/include/asm-generic/video.h @@ -0,0 +1,136 @@ +/* SPDX-License-Identifier: GPL-2.0 */ + +#ifndef __ASM_GENERIC_VIDEO_H_ +#define __ASM_GENERIC_VIDEO_H_ + +/* + * Only include this header file from your architecture's . + */ + +#include +#include +#include +#include + +struct device; + +#ifndef pgprot_framebuffer +#define pgprot_framebuffer pgprot_framebuffer +static inline pgprot_t pgprot_framebuffer(pgprot_t prot, + unsigned long vm_start, unsigned long vm_end, + unsigned long offset) +{ + return pgprot_writecombine(prot); +} +#endif + +#ifndef video_is_primary_device +#define video_is_primary_device video_is_primary_device +static inline bool video_is_primary_device(struct device *dev) +{ + return false; +} +#endif + +/* + * I/O helpers for the framebuffer. Prefer these functions over their + * regular counterparts. The regular I/O functions provide in-order + * access and swap bytes to/from little-endian ordering. Neither is + * required for framebuffers. Instead, the helpers read and write + * raw framebuffer data. Independent operations can be reordered for + * improved performance. + */ + +#ifndef fb_readb +static inline u8 fb_readb(const volatile void __iomem *addr) +{ + return __raw_readb(addr); +} +#define fb_readb fb_readb +#endif + +#ifndef fb_readw +static inline u16 fb_readw(const volatile void __iomem *addr) +{ + return __raw_readw(addr); +} +#define fb_readw fb_readw +#endif + +#ifndef fb_readl +static inline u32 fb_readl(const volatile void __iomem *addr) +{ + return __raw_readl(addr); +} +#define fb_readl fb_readl +#endif + +#ifndef fb_readq +#if defined(__raw_readq) +static inline u64 fb_readq(const volatile void __iomem *addr) +{ + return __raw_readq(addr); +} +#define fb_readq fb_readq +#endif +#endif + +#ifndef fb_writeb +static inline void fb_writeb(u8 b, volatile void __iomem *addr) +{ + __raw_writeb(b, addr); +} +#define fb_writeb fb_writeb +#endif + +#ifndef fb_writew +static inline void fb_writew(u16 b, volatile void __iomem *addr) +{ + __raw_writew(b, addr); +} +#define fb_writew fb_writew +#endif + +#ifndef fb_writel +static inline void fb_writel(u32 b, volatile void __iomem *addr) +{ + __raw_writel(b, addr); +} +#define fb_writel fb_writel +#endif + +#ifndef fb_writeq +#if defined(__raw_writeq) +static inline void fb_writeq(u64 b, volatile void __iomem *addr) +{ + __raw_writeq(b, addr); +} +#define fb_writeq fb_writeq +#endif +#endif + +#ifndef fb_memcpy_fromio +static inline void fb_memcpy_fromio(void *to, const volatile void __iomem *from, size_t n) +{ + memcpy_fromio(to, from, n); +} +#define fb_memcpy_fromio fb_memcpy_fromio +#endif + +#ifndef fb_memcpy_toio +static inline void fb_memcpy_toio(volatile void __iomem *to, const void *from, size_t n) +{ + memcpy_toio(to, from, n); +} +#define fb_memcpy_toio fb_memcpy_toio +#endif + +#ifndef fb_memset +static inline void fb_memset_io(volatile void __iomem *addr, int c, size_t n) +{ + memset_io(addr, c, n); +} +#define fb_memset fb_memset_io +#endif + +#endif /* __ASM_GENERIC_VIDEO_H_ */ -- cgit v1.3.1