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 --- drivers/video/fbdev/sbuslib.h | 63 +++++++++++++++++++++++++++++++++++++++++++ 1 file changed, 63 insertions(+) create mode 100644 drivers/video/fbdev/sbuslib.h (limited to 'drivers/video/fbdev/sbuslib.h') diff --git a/drivers/video/fbdev/sbuslib.h b/drivers/video/fbdev/sbuslib.h new file mode 100644 index 000000000..e9af2dc93 --- /dev/null +++ b/drivers/video/fbdev/sbuslib.h @@ -0,0 +1,63 @@ +/* SPDX-License-Identifier: GPL-2.0 */ +/* sbuslib.h: SBUS fb helper library interfaces */ +#ifndef _SBUSLIB_H +#define _SBUSLIB_H + +struct device_node; +struct fb_info; +struct fb_var_screeninfo; +struct vm_area_struct; + +struct sbus_mmap_map { + unsigned long voff; + unsigned long poff; + unsigned long size; +}; + +#define SBUS_MMAP_FBSIZE(n) (-n) +#define SBUS_MMAP_EMPTY 0x80000000 + +extern void sbusfb_fill_var(struct fb_var_screeninfo *var, + struct device_node *dp, int bpp); +extern int sbusfb_mmap_helper(const struct sbus_mmap_map *map, + unsigned long physbase, unsigned long fbsize, + unsigned long iospace, + struct vm_area_struct *vma); +int sbusfb_ioctl_helper(unsigned long cmd, unsigned long arg, + struct fb_info *info, + int type, int fb_depth, unsigned long fb_size); +int sbusfb_compat_ioctl(struct fb_info *info, unsigned int cmd, + unsigned long arg); + +/* + * Initialize struct fb_ops for SBUS I/O. + */ + +#define __FB_DEFAULT_SBUS_OPS_RDWR(__prefix) \ + .fb_read = fb_io_read, \ + .fb_write = fb_io_write + +#define __FB_DEFAULT_SBUS_OPS_DRAW(__prefix) \ + .fb_fillrect = cfb_fillrect, \ + .fb_copyarea = cfb_copyarea, \ + .fb_imageblit = cfb_imageblit + +#ifdef CONFIG_COMPAT +#define __FB_DEFAULT_SBUS_OPS_IOCTL(__prefix) \ + .fb_ioctl = __prefix ## _sbusfb_ioctl, \ + .fb_compat_ioctl = sbusfb_compat_ioctl +#else +#define __FB_DEFAULT_SBUS_OPS_IOCTL(__prefix) \ + .fb_ioctl = __prefix ## _sbusfb_ioctl +#endif + +#define __FB_DEFAULT_SBUS_OPS_MMAP(__prefix) \ + .fb_mmap = __prefix ## _sbusfb_mmap + +#define FB_DEFAULT_SBUS_OPS(__prefix) \ + __FB_DEFAULT_SBUS_OPS_RDWR(__prefix), \ + __FB_DEFAULT_SBUS_OPS_DRAW(__prefix), \ + __FB_DEFAULT_SBUS_OPS_IOCTL(__prefix), \ + __FB_DEFAULT_SBUS_OPS_MMAP(__prefix) + +#endif /* _SBUSLIB_H */ -- cgit v1.3.1