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/powerpc/boot/string.S | 252 +++++++++++++++++++++++++++++++++++++++++++++ 1 file changed, 252 insertions(+) create mode 100644 arch/powerpc/boot/string.S (limited to 'arch/powerpc/boot/string.S') diff --git a/arch/powerpc/boot/string.S b/arch/powerpc/boot/string.S new file mode 100644 index 000000000..76801eb6d --- /dev/null +++ b/arch/powerpc/boot/string.S @@ -0,0 +1,252 @@ +/* SPDX-License-Identifier: GPL-2.0-or-later */ +/* + * Copyright (C) Paul Mackerras 1997. + * + * NOTE: this code runs in 32 bit mode and is packaged as ELF32. + */ + +#include "ppc_asm.h" + + .text + .globl strcpy +strcpy: + addi r5,r3,-1 + addi r4,r4,-1 +1: lbzu r0,1(r4) + cmpwi 0,r0,0 + stbu r0,1(r5) + bne 1b + blr + + .globl strcat +strcat: + addi r5,r3,-1 + addi r4,r4,-1 +1: lbzu r0,1(r5) + cmpwi 0,r0,0 + bne 1b + addi r5,r5,-1 +1: lbzu r0,1(r4) + cmpwi 0,r0,0 + stbu r0,1(r5) + bne 1b + blr + + .globl strchr +strchr: + addi r3,r3,-1 +1: lbzu r0,1(r3) + cmpw 0,r0,r4 + beqlr + cmpwi 0,r0,0 + bne 1b + li r3,0 + blr + + .globl strcmp +strcmp: + addi r5,r3,-1 + addi r4,r4,-1 +1: lbzu r3,1(r5) + cmpwi 1,r3,0 + lbzu r0,1(r4) + subf. r3,r0,r3 + beqlr 1 + beq 1b + blr + + .globl strncmp +strncmp: + mtctr r5 + addi r5,r3,-1 + addi r4,r4,-1 +1: lbzu r3,1(r5) + cmpwi 1,r3,0 + lbzu r0,1(r4) + subf. r3,r0,r3 + beqlr 1 + bdnzt eq,1b + blr + + .globl strlen +strlen: + addi r4,r3,-1 +1: lbzu r0,1(r4) + cmpwi 0,r0,0 + bne 1b + subf r3,r3,r4 + blr + + .globl memset +memset: + rlwimi r4,r4,8,16,23 + rlwimi r4,r4,16,0,15 + addi r6,r3,-4 + cmplwi 0,r5,4 + blt 7f + stwu r4,4(r6) + beqlr + andi. r0,r6,3 + add r5,r0,r5 + subf r6,r0,r6 + rlwinm r0,r5,32-2,2,31 + mtctr r0 + bdz 6f +1: stwu r4,4(r6) + bdnz 1b +6: andi. r5,r5,3 +7: cmpwi 0,r5,0 + beqlr + mtctr r5 + addi r6,r6,3 +8: stbu r4,1(r6) + bdnz 8b + blr + + .globl memmove +memmove: + cmplw 0,r3,r4 + bgt backwards_memcpy + /* fall through */ + + .globl memcpy +memcpy: + rlwinm. r7,r5,32-3,3,31 /* r7 = r5 >> 3 */ + addi r6,r3,-4 + addi r4,r4,-4 + beq 3f /* if less than 8 bytes to do */ + andi. r0,r6,3 /* get dest word aligned */ + mtctr r7 + bne 5f + andi. r0,r4,3 /* check src word aligned too */ + bne 3f +1: lwz r7,4(r4) + lwzu r8,8(r4) + stw r7,4(r6) + stwu r8,8(r6) + bdnz 1b + andi. r5,r5,7 +2: cmplwi 0,r5,4 + blt 3f + lwzu r0,4(r4) + addi r5,r5,-4 + stwu r0,4(r6) +3: cmpwi 0,r5,0 + beqlr + mtctr r5 + addi r4,r4,3 + addi r6,r6,3 +4: lbzu r0,1(r4) + stbu r0,1(r6) + bdnz 4b + blr +5: subfic r0,r0,4 + cmpw cr1,r0,r5 + add r7,r0,r4 + andi. r7,r7,3 /* will source be word-aligned too? */ + ble cr1,3b + bne 3b /* do byte-by-byte if not */ + mtctr r0 +6: lbz r7,4(r4) + addi r4,r4,1 + stb r7,4(r6) + addi r6,r6,1 + bdnz 6b + subf r5,r0,r5 + rlwinm. r7,r5,32-3,3,31 + beq 2b + mtctr r7 + b 1b + + .globl backwards_memcpy +backwards_memcpy: + rlwinm. r7,r5,32-3,3,31 /* r7 = r5 >> 3 */ + add r6,r3,r5 + add r4,r4,r5 + beq 3f + andi. r0,r6,3 + mtctr r7 + bne 5f + andi. r0,r4,3 + bne 3f +1: lwz r7,-4(r4) + lwzu r8,-8(r4) + stw r7,-4(r6) + stwu r8,-8(r6) + bdnz 1b + andi. r5,r5,7 +2: cmplwi 0,r5,4 + blt 3f + lwzu r0,-4(r4) + subi r5,r5,4 + stwu r0,-4(r6) +3: cmpwi 0,r5,0 + beqlr + mtctr r5 +4: lbzu r0,-1(r4) + stbu r0,-1(r6) + bdnz 4b + blr +5: cmpw cr1,r0,r5 + subf r7,r0,r4 + andi. r7,r7,3 + ble cr1,3b + bne 3b + mtctr r0 +6: lbzu r7,-1(r4) + stbu r7,-1(r6) + bdnz 6b + subf r5,r0,r5 + rlwinm. r7,r5,32-3,3,31 + beq 2b + mtctr r7 + b 1b + + .globl memchr +memchr: + cmpwi 0,r5,0 + blelr + mtctr r5 + addi r3,r3,-1 +1: lbzu r0,1(r3) + cmpw r0,r4 + beqlr + bdnz 1b + li r3,0 + blr + + .globl memcmp +memcmp: + cmpwi 0,r5,0 + ble 2f + mtctr r5 + addi r6,r3,-1 + addi r4,r4,-1 +1: lbzu r3,1(r6) + lbzu r0,1(r4) + subf. r3,r0,r3 + bdnzt 2,1b + blr +2: li r3,0 + blr + + +/* + * Flush the dcache and invalidate the icache for a range of addresses. + * + * flush_cache(addr, len) + */ + .global flush_cache +flush_cache: + addi 4,4,0x1f /* len = (len + 0x1f) / 0x20 */ + rlwinm. 4,4,27,5,31 + mtctr 4 + beqlr +1: dcbf 0,3 + icbi 0,3 + addi 3,3,0x20 + bdnz 1b + sync + isync + blr + -- cgit v1.3.1