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Eric Biggers
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Add a NEON-accelerated implementation of Speck128-XTS and Speck64-XTS for ARM64. This is ported from the 32-bit version. It may be useful on devices with 64-bit ARM CPUs that don't have the Cryptography Extensions, so cannot do AES efficiently -- e.g. the Cortex-A53 processor on the Raspberry Pi 3. It generally works the same way as the 32-bit version, but there are some slight differences due to the different instructions, registers, and syntax available in ARM64 vs. in ARM32. For example, in the 64-bit version there are enough registers to hold the XTS tweaks for each 128-byte chunk, so they don't need to be saved on the stack. Benchmarks on a Raspberry Pi 3 running a 64-bit kernel: Algorithm Encryption Decryption --------- ---------- ---------- Speck64/128-XTS (NEON) 92.2 MB/s 92.2 MB/s Speck128/256-XTS (NEON) 75.0 MB/s 75.0 MB/s Speck128/256-XTS (generic) 47.4 MB/s 35.6 MB/s AES-128-XTS (NEON bit-sliced) 33.4 MB/s 29.6 MB/s AES-256-XTS (NEON bit-sliced) 24.6 MB/s 21.7 MB/s The code performs well on higher-end ARM64 processors as well, though such processors tend to have the Crypto Extensions which make AES preferred. For example, here are the same benchmarks run on a HiKey960 (with CPU affinity set for the A73 cores), with the Crypto Extensions implementation of AES-256-XTS added: Algorithm Encryption Decryption --------- ----------- ----------- AES-256-XTS (Crypto Extensions) 1273.3 MB/s 1274.7 MB/s Speck64/128-XTS (NEON) 359.8 MB/s 348.0 MB/s Speck128/256-XTS (NEON) 292.5 MB/s 286.1 MB/s Speck128/256-XTS (generic) 186.3 MB/s 181.8 MB/s AES-128-XTS (NEON bit-sliced) 142.0 MB/s 124.3 MB/s AES-256-XTS (NEON bit-sliced) 104.7 MB/s 91.1 MB/s Signed-off-by: Eric Biggers <ebiggers@google.com> Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>
Linux kernel ============ This file was moved to Documentation/admin-guide/README.rst Please notice that there are several guides for kernel developers and users. These guides can be rendered in a number of formats, like HTML and PDF. In order to build the documentation, use ``make htmldocs`` or ``make pdfdocs``. There are various text files in the Documentation/ subdirectory, several of them using the Restructured Text markup notation. See Documentation/00-INDEX for a list of what is contained in each file. 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.