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Eric Biggers
22375adaa0
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: 49aa7c00ed ("crypto: mips/chacha - import 32r2 ChaCha code from Zinc")
Cc: stable@vger.kernel.org
Reported-by: kernel test robot <lkp@intel.com>
Closes: https://lore.kernel.org/oe-kbuild-all/202505080409.EujEBwA0-lkp@intel.com/
Link: https://lore.kernel.org/r/20250619225535.679301-1-ebiggers@kernel.org
Signed-off-by: Eric Biggers <ebiggers@kernel.org>
Linux kernel
============
There are several guides for kernel developers and users. These guides can
be rendered in a number of formats, like HTML and PDF. Please read
Documentation/admin-guide/README.rst first.
In order to build the documentation, use ``make htmldocs`` or
``make pdfdocs``. The formatted documentation can also be read online at:
https://www.kernel.org/doc/html/latest/
There are various text files in the Documentation/ subdirectory,
several of them using the reStructuredText markup notation.
Please read the Documentation/process/changes.rst file, as it contains the
requirements for building and running the kernel, and information about
the problems which may result by upgrading your kernel.