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 --- tools/testing/vsock/timeout.c | 78 +++++++++++++++++++++++++++++++++++++++++++ 1 file changed, 78 insertions(+) create mode 100644 tools/testing/vsock/timeout.c (limited to 'tools/testing/vsock/timeout.c') diff --git a/tools/testing/vsock/timeout.c b/tools/testing/vsock/timeout.c new file mode 100644 index 000000000..1453d38e0 --- /dev/null +++ b/tools/testing/vsock/timeout.c @@ -0,0 +1,78 @@ +// SPDX-License-Identifier: GPL-2.0-only +/* Timeout API for single-threaded programs that use blocking + * syscalls (read/write/send/recv/connect/accept). + * + * Copyright (C) 2017 Red Hat, Inc. + * + * Author: Stefan Hajnoczi + */ + +/* Use the following pattern: + * + * timeout_begin(TIMEOUT); + * do { + * ret = accept(...); + * timeout_check("accept"); + * } while (ret < 0 && ret == EINTR); + * timeout_end(); + */ + +#include +#include +#include +#include +#include +#include "timeout.h" + +static volatile bool timeout; + +/* SIGALRM handler function. Do not use sleep(2), alarm(2), or + * setitimer(2) while using this API - they may interfere with each + * other. + * + * If you need to sleep, please use timeout_sleep() provided by this API. + */ +void sigalrm(int signo) +{ + timeout = true; +} + +/* Start a timeout. Call timeout_check() to verify that the timeout hasn't + * expired. timeout_end() must be called to stop the timeout. Timeouts cannot + * be nested. + */ +void timeout_begin(unsigned int seconds) +{ + alarm(seconds); +} + +/* Exit with an error message if the timeout has expired */ +void timeout_check(const char *operation) +{ + if (timeout) { + fprintf(stderr, "%s timed out\n", operation); + exit(EXIT_FAILURE); + } +} + +/* Stop a timeout */ +void timeout_end(void) +{ + alarm(0); + timeout = false; +} + +/* Sleep in a timeout section. + * + * nanosleep(2) can be used with this API since POSIX.1 explicitly + * specifies that it does not interact with signals. + */ +int timeout_usleep(useconds_t usec) +{ + struct timespec ts = { + .tv_sec = usec / 1000000, + .tv_nsec = (usec % 1000000) * 1000, + }; + + return nanosleep(&ts, NULL); +} -- cgit v1.3.1