• Ard Biesheuvel's avatar
    crypto: arm64/aes-ce-ccm - move kernel mode neon en/disable into loop · bd2ad885
    Ard Biesheuvel authored
    When kernel mode NEON was first introduced on arm64, the preserve and
    restore of the userland NEON state was completely unoptimized, and
    involved saving all registers on each call to kernel_neon_begin(),
    and restoring them on each call to kernel_neon_end(). For this reason,
    the NEON crypto code that was introduced at the time keeps the NEON
    enabled throughout the execution of the crypto API methods, which may
    include calls back into the crypto API that could result in memory
    allocation or other actions that we should avoid when running with
    preemption disabled.
    
    Since then, we have optimized the kernel mode NEON handling, which now
    restores lazily (upon return to userland), and so the preserve action
    is only costly the first time it is called after entering the kernel.
    
    So let's put the kernel_neon_begin() and kernel_neon_end() calls around
    the actual invocations of the NEON crypto code, and run the remainder of
    the code with kernel mode NEON disabled (and preemption enabled)
    Signed-off-by: default avatarArd Biesheuvel <ard.biesheuvel@linaro.org>
    Signed-off-by: default avatarHerbert Xu <herbert@gondor.apana.org.au>
    bd2ad885
aes-ce-ccm-glue.c 9.49 KB