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/uapi/asm-generic/poll.h | 42 +++++++++++++++++++++++++++++++++++++++++ 1 file changed, 42 insertions(+) create mode 100644 include/uapi/asm-generic/poll.h (limited to 'include/uapi/asm-generic/poll.h') diff --git a/include/uapi/asm-generic/poll.h b/include/uapi/asm-generic/poll.h new file mode 100644 index 000000000..f9c520ce4 --- /dev/null +++ b/include/uapi/asm-generic/poll.h @@ -0,0 +1,42 @@ +/* SPDX-License-Identifier: GPL-2.0 WITH Linux-syscall-note */ +#ifndef __ASM_GENERIC_POLL_H +#define __ASM_GENERIC_POLL_H + +/* These are specified by iBCS2 */ +#define POLLIN 0x0001 +#define POLLPRI 0x0002 +#define POLLOUT 0x0004 +#define POLLERR 0x0008 +#define POLLHUP 0x0010 +#define POLLNVAL 0x0020 + +/* The rest seem to be more-or-less nonstandard. Check them! */ +#define POLLRDNORM 0x0040 +#define POLLRDBAND 0x0080 +#ifndef POLLWRNORM +#define POLLWRNORM 0x0100 +#endif +#ifndef POLLWRBAND +#define POLLWRBAND 0x0200 +#endif +#ifndef POLLMSG +#define POLLMSG 0x0400 +#endif +#ifndef POLLREMOVE +#define POLLREMOVE 0x1000 +#endif +#ifndef POLLRDHUP +#define POLLRDHUP 0x2000 +#endif + +#define POLLFREE (__force __poll_t)0x4000 + +#define POLL_BUSY_LOOP (__force __poll_t)0x8000 + +struct pollfd { + int fd; + short events; + short revents; +}; + +#endif /* __ASM_GENERIC_POLL_H */ -- cgit v1.3.1