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 --- arch/microblaze/lib/memmove.c | 195 ++++++++++++++++++++++++++++++++++++++++++ 1 file changed, 195 insertions(+) create mode 100644 arch/microblaze/lib/memmove.c (limited to 'arch/microblaze/lib/memmove.c') diff --git a/arch/microblaze/lib/memmove.c b/arch/microblaze/lib/memmove.c new file mode 100644 index 000000000..c1f08c484 --- /dev/null +++ b/arch/microblaze/lib/memmove.c @@ -0,0 +1,195 @@ +/* + * Copyright (C) 2008-2009 Michal Simek + * Copyright (C) 2008-2009 PetaLogix + * Copyright (C) 2007 John Williams + * + * Reasonably optimised generic C-code for memcpy on Microblaze + * This is generic C code to do efficient, alignment-aware memmove. + * + * It is based on demo code originally Copyright 2001 by Intel Corp, taken from + * http://www.embedded.com/showArticle.jhtml?articleID=19205567 + * + * Attempts were made, unsuccessfully, to contact the original + * author of this code (Michael Morrow, Intel). Below is the original + * copyright notice. + * + * This software has been developed by Intel Corporation. + * Intel specifically disclaims all warranties, express or + * implied, and all liability, including consequential and + * other indirect damages, for the use of this program, including + * liability for infringement of any proprietary rights, + * and including the warranties of merchantability and fitness + * for a particular purpose. Intel does not assume any + * responsibility for and errors which may appear in this program + * not any responsibility to update it. + */ + +#include +#include +#include +#include +#include + +#ifdef CONFIG_OPT_LIB_FUNCTION +void *memmove(void *v_dst, const void *v_src, __kernel_size_t c) +{ + const char *src = v_src; + char *dst = v_dst; + const uint32_t *i_src; + uint32_t *i_dst; + + if (!c) + return v_dst; + + /* Use memcpy when source is higher than dest */ + if (v_dst <= v_src) + return memcpy(v_dst, v_src, c); + + /* The following code tries to optimize the copy by using unsigned + * alignment. This will work fine if both source and destination are + * aligned on the same boundary. However, if they are aligned on + * different boundaries shifts will be necessary. This might result in + * bad performance on MicroBlaze systems without a barrel shifter. + */ + /* FIXME this part needs more test */ + /* Do a descending copy - this is a bit trickier! */ + dst += c; + src += c; + + if (c >= 4) { + unsigned value, buf_hold; + + /* Align the destination to a word boundary. */ + /* This is done in an endian independent manner. */ + + switch ((unsigned long)dst & 3) { + case 3: + *--dst = *--src; + --c; + fallthrough; + case 2: + *--dst = *--src; + --c; + fallthrough; + case 1: + *--dst = *--src; + --c; + } + + i_dst = (void *)dst; + /* Choose a copy scheme based on the source */ + /* alignment relative to destination. */ + switch ((unsigned long)src & 3) { + case 0x0: /* Both byte offsets are aligned */ + + i_src = (const void *)src; + + for (; c >= 4; c -= 4) + *--i_dst = *--i_src; + + src = (const void *)i_src; + break; + case 0x1: /* Unaligned - Off by 1 */ + /* Word align the source */ + i_src = (const void *) (((unsigned)src + 4) & ~3); +#ifndef __MICROBLAZEEL__ + /* Load the holding buffer */ + buf_hold = *--i_src >> 24; + + for (; c >= 4; c -= 4) { + value = *--i_src; + *--i_dst = buf_hold << 8 | value; + buf_hold = value >> 24; + } +#else + /* Load the holding buffer */ + buf_hold = (*--i_src & 0xFF) << 24; + + for (; c >= 4; c -= 4) { + value = *--i_src; + *--i_dst = buf_hold | + ((value & 0xFFFFFF00) >> 8); + buf_hold = (value & 0xFF) << 24; + } +#endif + /* Realign the source */ + src = (const void *)i_src; + src += 1; + break; + case 0x2: /* Unaligned - Off by 2 */ + /* Word align the source */ + i_src = (const void *) (((unsigned)src + 4) & ~3); +#ifndef __MICROBLAZEEL__ + /* Load the holding buffer */ + buf_hold = *--i_src >> 16; + + for (; c >= 4; c -= 4) { + value = *--i_src; + *--i_dst = buf_hold << 16 | value; + buf_hold = value >> 16; + } +#else + /* Load the holding buffer */ + buf_hold = (*--i_src & 0xFFFF) << 16; + + for (; c >= 4; c -= 4) { + value = *--i_src; + *--i_dst = buf_hold | + ((value & 0xFFFF0000) >> 16); + buf_hold = (value & 0xFFFF) << 16; + } +#endif + /* Realign the source */ + src = (const void *)i_src; + src += 2; + break; + case 0x3: /* Unaligned - Off by 3 */ + /* Word align the source */ + i_src = (const void *) (((unsigned)src + 4) & ~3); +#ifndef __MICROBLAZEEL__ + /* Load the holding buffer */ + buf_hold = *--i_src >> 8; + + for (; c >= 4; c -= 4) { + value = *--i_src; + *--i_dst = buf_hold << 24 | value; + buf_hold = value >> 8; + } +#else + /* Load the holding buffer */ + buf_hold = (*--i_src & 0xFFFFFF) << 8; + + for (; c >= 4; c -= 4) { + value = *--i_src; + *--i_dst = buf_hold | + ((value & 0xFF000000) >> 24); + buf_hold = (value & 0xFFFFFF) << 8; + } +#endif + /* Realign the source */ + src = (const void *)i_src; + src += 3; + break; + } + dst = (void *)i_dst; + } + + /* simple fast copy, ... unless a cache boundary is crossed */ + /* Finish off any remaining bytes */ + switch (c) { + case 4: + *--dst = *--src; + fallthrough; + case 3: + *--dst = *--src; + fallthrough; + case 2: + *--dst = *--src; + fallthrough; + case 1: + *--dst = *--src; + } + return v_dst; +} +EXPORT_SYMBOL(memmove); +#endif /* CONFIG_OPT_LIB_FUNCTION */ -- cgit v1.3.1