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The generic AES code provides four sets of lookup tables, where each set consists of four tables containing the same 32-bit values, but rotated by 0, 8, 16 and 24 bits, respectively. This makes sense for CISC architectures such as x86 which support memory operands, but for other architectures, the rotates are quite cheap, and using all four tables needlessly thrashes the D-cache, and actually hurts rather than helps performance. Since x86 already has its own implementation of AEGIS based on AES-NI instructions, let's tweak the generic implementation towards other architectures, and avoid the prerotated tables, and perform the rotations inline. On ARM Cortex-A53, this results in a ~8% speedup. Acked-by: Ondrej Mosnacek <omosnace@redhat.com> Signed-off-by: Ard Biesheuvel <ard.biesheuvel@linaro.org> Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>
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 Restructured Text 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.