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/dibs/dibs_loopback.h | 57 ++++++++++++++++++++++++++++++++++++++++++++ 1 file changed, 57 insertions(+) create mode 100644 drivers/dibs/dibs_loopback.h (limited to 'drivers/dibs/dibs_loopback.h') diff --git a/drivers/dibs/dibs_loopback.h b/drivers/dibs/dibs_loopback.h new file mode 100644 index 000000000..0664f6a8e --- /dev/null +++ b/drivers/dibs/dibs_loopback.h @@ -0,0 +1,57 @@ +/* SPDX-License-Identifier: GPL-2.0 */ +/* + * dibs loopback (aka loopback-ism) device structure definitions. + * + * Copyright (c) 2024, Alibaba Inc. + * + * Author: Wen Gu + * Tony Lu + * + */ + +#ifndef _DIBS_LOOPBACK_H +#define _DIBS_LOOPBACK_H + +#include +#include +#include +#include +#include + +#if IS_ENABLED(CONFIG_DIBS_LO) +#define DIBS_LO_DMBS_HASH_BITS 12 +#define DIBS_LO_MAX_DMBS 5000 + +struct dibs_lo_dmb_node { + struct hlist_node list; + u64 token; + u32 len; + u32 sba_idx; + void *cpu_addr; + dma_addr_t dma_addr; + refcount_t refcnt; +}; + +struct dibs_lo_dev { + struct dibs_dev *dibs; + atomic_t dmb_cnt; + rwlock_t dmb_ht_lock; + DECLARE_BITMAP(sba_idx_mask, DIBS_LO_MAX_DMBS); + DECLARE_HASHTABLE(dmb_ht, DIBS_LO_DMBS_HASH_BITS); + wait_queue_head_t ldev_release; +}; + +int dibs_loopback_init(void); +void dibs_loopback_exit(void); +#else +static inline int dibs_loopback_init(void) +{ + return 0; +} + +static inline void dibs_loopback_exit(void) +{ +} +#endif + +#endif /* _DIBS_LOOPBACK_H */ -- cgit v1.3.1