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/irqflags.h | 67 ++++++++++++++++++++++++++++++++++++++++++ 1 file changed, 67 insertions(+) create mode 100644 include/asm-generic/irqflags.h (limited to 'include/asm-generic/irqflags.h') diff --git a/include/asm-generic/irqflags.h b/include/asm-generic/irqflags.h new file mode 100644 index 000000000..19ccbf483 --- /dev/null +++ b/include/asm-generic/irqflags.h @@ -0,0 +1,67 @@ +/* SPDX-License-Identifier: GPL-2.0 */ +#ifndef __ASM_GENERIC_IRQFLAGS_H +#define __ASM_GENERIC_IRQFLAGS_H + +/* + * All architectures should implement at least the first two functions, + * usually inline assembly will be the best way. + */ +#ifndef ARCH_IRQ_DISABLED +#define ARCH_IRQ_DISABLED 0 +#define ARCH_IRQ_ENABLED 1 +#endif + +/* read interrupt enabled status */ +#ifndef arch_local_save_flags +unsigned long arch_local_save_flags(void); +#endif + +/* set interrupt enabled status */ +#ifndef arch_local_irq_restore +void arch_local_irq_restore(unsigned long flags); +#endif + +/* get status and disable interrupts */ +#ifndef arch_local_irq_save +static inline unsigned long arch_local_irq_save(void) +{ + unsigned long flags; + flags = arch_local_save_flags(); + arch_local_irq_restore(ARCH_IRQ_DISABLED); + return flags; +} +#endif + +/* test flags */ +#ifndef arch_irqs_disabled_flags +static inline int arch_irqs_disabled_flags(unsigned long flags) +{ + return flags == ARCH_IRQ_DISABLED; +} +#endif + +/* unconditionally enable interrupts */ +#ifndef arch_local_irq_enable +static inline void arch_local_irq_enable(void) +{ + arch_local_irq_restore(ARCH_IRQ_ENABLED); +} +#endif + +/* unconditionally disable interrupts */ +#ifndef arch_local_irq_disable +static inline void arch_local_irq_disable(void) +{ + arch_local_irq_restore(ARCH_IRQ_DISABLED); +} +#endif + +/* test hardware interrupt enable bit */ +#ifndef arch_irqs_disabled +static inline int arch_irqs_disabled(void) +{ + return arch_irqs_disabled_flags(arch_local_save_flags()); +} +#endif + +#endif /* __ASM_GENERIC_IRQFLAGS_H */ -- cgit v1.3.1