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 --- crypto/842.c | 87 ++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++ 1 file changed, 87 insertions(+) create mode 100644 crypto/842.c (limited to 'crypto/842.c') diff --git a/crypto/842.c b/crypto/842.c new file mode 100644 index 000000000..4007e87be --- /dev/null +++ b/crypto/842.c @@ -0,0 +1,87 @@ +// SPDX-License-Identifier: GPL-2.0-or-later +/* + * Cryptographic API for the 842 software compression algorithm. + * + * Copyright (C) IBM Corporation, 2011-2015 + * + * Original Authors: Robert Jennings + * Seth Jennings + * + * Rewrite: Dan Streetman + * + * This is the software implementation of compression and decompression using + * the 842 format. This uses the software 842 library at lib/842/ which is + * only a reference implementation, and is very, very slow as compared to other + * software compressors. You probably do not want to use this software + * compression. If you have access to the PowerPC 842 compression hardware, you + * want to use the 842 hardware compression interface, which is at: + * drivers/crypto/nx/nx-842-crypto.c + */ + +#include +#include +#include +#include + +static void *crypto842_alloc_ctx(void) +{ + void *ctx; + + ctx = kmalloc(SW842_MEM_COMPRESS, GFP_KERNEL); + if (!ctx) + return ERR_PTR(-ENOMEM); + + return ctx; +} + +static void crypto842_free_ctx(void *ctx) +{ + kfree(ctx); +} + +static int crypto842_scompress(struct crypto_scomp *tfm, + const u8 *src, unsigned int slen, + u8 *dst, unsigned int *dlen, void *ctx) +{ + return sw842_compress(src, slen, dst, dlen, ctx); +} + +static int crypto842_sdecompress(struct crypto_scomp *tfm, + const u8 *src, unsigned int slen, + u8 *dst, unsigned int *dlen, void *ctx) +{ + return sw842_decompress(src, slen, dst, dlen); +} + +static struct scomp_alg scomp = { + .streams = { + .alloc_ctx = crypto842_alloc_ctx, + .free_ctx = crypto842_free_ctx, + }, + .compress = crypto842_scompress, + .decompress = crypto842_sdecompress, + .base = { + .cra_name = "842", + .cra_driver_name = "842-scomp", + .cra_priority = 100, + .cra_module = THIS_MODULE, + } +}; + +static int __init crypto842_mod_init(void) +{ + return crypto_register_scomp(&scomp); +} +module_init(crypto842_mod_init); + +static void __exit crypto842_mod_exit(void) +{ + crypto_unregister_scomp(&scomp); +} +module_exit(crypto842_mod_exit); + +MODULE_LICENSE("GPL"); +MODULE_DESCRIPTION("842 Software Compression Algorithm"); +MODULE_ALIAS_CRYPTO("842"); +MODULE_ALIAS_CRYPTO("842-generic"); +MODULE_AUTHOR("Dan Streetman "); -- cgit v1.3.1