On Thu, Jun 19, 2025 at 03:55:35PM -0700, Eric Biggers wrote:
> The MIPS32r2 ChaCha code has never been buildable with the clang
> assembler. First, clang doesn't support the 'rotl' pseudo-instruction:
>
> error: unknown instruction, did you mean: rol, rotr?
>
> Second, clang requires that both operands of the 'wsbh' instruction be
> explicitly given:
>
> error: too few operands for instruction
>
> To fix this, align the code with the real instruction set by (1) using
> the real instruction 'rotr' instead of the nonstandard pseudo-
> instruction 'rotl', and (2) explicitly giving both operands to 'wsbh'.
>
> To make removing the use of 'rotl' a bit easier, also remove the
> unnecessary special-casing for big endian CPUs at
> .Lchacha_mips_xor_bytes. The tail handling is actually
> endian-independent since it processes one byte at a time. On big endian
> CPUs the old code byte-swapped SAVED_X, then iterated through it in
> reverse order. But the byteswap and reverse iteration canceled out.
>
> Tested with chacha20poly1305-selftest in QEMU using "-M malta" with both
> little endian and big endian mips32r2 kernels.
>
> Fixes: 49aa7c00eddf ("crypto: mips/chacha - import 32r2 ChaCha code from Zinc")
> Cc: stable@xxxxxxxxxxxxxxx
> Reported-by: kernel test robot <lkp@xxxxxxxxx>
> Closes: https://lore.kernel.org/oe-kbuild-all/202505080409.EujEBwA0-lkp@xxxxxxxxx/
> Signed-off-by: Eric Biggers <ebiggers@xxxxxxxxxx>
> ---
>
> This applies on top of other pending lib/crypto patches and can be
> retrieved from git at:
>
> git fetch https://git.kernel.org/pub/scm/linux/kernel/git/ebiggers/linux.git mips-chacha-fix
>
> lib/crypto/mips/chacha-core.S | 20 +++++++-------------
> 1 file changed, 7 insertions(+), 13 deletions(-)
Applied to https://git.kernel.org/pub/scm/linux/kernel/git/ebiggers/linux.git/log/?h=libcrypto-next
- Eric
