• Jason A. Donenfeld's avatar
    crypto: arm/curve25519 - wire up NEON implementation · d8f1308a
    Jason A. Donenfeld authored
    This ports the SUPERCOP implementation for usage in kernel space. In
    addition to the usual header, macro, and style changes required for
    kernel space, it makes a few small changes to the code:
    
      - The stack alignment is relaxed to 16 bytes.
      - Superfluous mov statements have been removed.
      - ldr for constants has been replaced with movw.
      - ldreq has been replaced with moveq.
      - The str epilogue has been made more idiomatic.
      - SIMD registers are not pushed and popped at the beginning and end.
      - The prologue and epilogue have been made idiomatic.
      - A hole has been removed from the stack, saving 32 bytes.
      - We write-back the base register whenever possible for vld1.8.
      - Some multiplications have been reordered for better A7 performance.
    
    There are more opportunities for cleanup, since this code is from qhasm,
    which doesn't always do the most opportune thing. But even prior to
    extensive hand optimizations, this code delivers significant performance
    improvements (given in get_cycles() per call):
    
    		      ----------- -------------
    	             | generic C | this commit |
    	 ------------ ----------- -------------
    	| Cortex-A7  |     49136 |       22395 |
    	 ------------ ----------- -------------
    	| Cortex-A17 |     17326 |        4983 |
    	 ------------ ----------- -------------
    Signed-off-by: default avatarJason A. Donenfeld <Jason@zx2c4.com>
    [ardb: - move to arch/arm/crypto
           - wire into lib/crypto framework
           - implement crypto API KPP hooks ]
    Signed-off-by: default avatarArd Biesheuvel <ardb@kernel.org>
    Signed-off-by: default avatarHerbert Xu <herbert@gondor.apana.org.au>
    d8f1308a
curve25519-core.S 45.9 KB