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/libcrypto-unauth-encryption.rst | 49 ++++++++++++++++++++++ 1 file changed, 49 insertions(+) create mode 100644 Documentation/crypto/libcrypto-unauth-encryption.rst (limited to 'Documentation/crypto/libcrypto-unauth-encryption.rst') diff --git a/Documentation/crypto/libcrypto-unauth-encryption.rst b/Documentation/crypto/libcrypto-unauth-encryption.rst new file mode 100644 index 000000000..b4639b892 --- /dev/null +++ b/Documentation/crypto/libcrypto-unauth-encryption.rst @@ -0,0 +1,49 @@ +.. SPDX-License-Identifier: GPL-2.0-or-later + +Unauthenticated encryption +========================== + +These APIs provide support for unauthenticated encryption and decryption, +including bare stream ciphers and other length-preserving algorithms such as +block ciphers in XTS mode. The legitimate use cases for these algorithms are: + +- Support for legacy protocols that really should have chosen an authenticated + mode (or even another primitive entirely) but didn't. + +- Internal components of authenticated modes. For example, AES-CTR is used by + AES-GCM and AES-CCM internally. + +- Storage encryption that cannot accommodate ciphertext expansion. Usually + AES-XTS is used for this. + +- Stream ciphers for key derivation and random number generation. + +Besides the above, these shouldn't be used. + +AES-CBC and AES-CBC-CTS +----------------------- + +This API provides support for AES in the CBC and CBC-CTS modes of operation. + +.. kernel-doc:: include/crypto/aes-cbc.h + +AES-CTR and AES-XCTR +-------------------- + +This API provides support for AES in the CTR and XCTR modes of operation. + +.. kernel-doc:: include/crypto/aes-ctr.h + +AES-ECB +------- + +This API provides support for AES in the ECB mode of operation. + +.. kernel-doc:: include/crypto/aes-ecb.h + +AES-XTS +------- + +This API provides support for AES in the XTS mode of operation. + +.. kernel-doc:: include/crypto/aes-xts.h -- cgit v1.3.1