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crypto: arm/chacha20 - always use vrev for 16-bit rotates 

The 4-way ChaCha20 NEON code implements 16-bit rotates with vrev32.16,
but the one-way code (used on remainder blocks) implements it with
vshl + vsri, which is slower.  Switch the one-way code to vrev32.16 too.

Signed-off-by: Eric Biggers <ebiggers@google.com>
Acked-by: Ard Biesheuvel <ard.biesheuvel@linaro.org>
Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>
This commit is contained in:
Eric Biggers 2018-07-24 18:29:07 -07:00 committed by Herbert Xu
parent f53ad3e1b3
commit 4e34e51f48
1 changed files with 4 additions and 6 deletions
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10
arch/arm/crypto/chacha20-neon-core.S
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@ -51,9 +51,8 @@ ENTRY(chacha20_block_xor_neon)
.Ldoubleround:
// x0 += x1, x3 = rotl32(x3 ^ x0, 16)
vadd.i32 q0, q0, q1
veor q4, q3, q0
vshl.u32 q3, q4, #16
vsri.u32 q3, q4, #16
veor q3, q3, q0
vrev32.16 q3, q3
// x2 += x3, x1 = rotl32(x1 ^ x2, 12)
vadd.i32 q2, q2, q3
@ -82,9 +81,8 @@ ENTRY(chacha20_block_xor_neon)
// x0 += x1, x3 = rotl32(x3 ^ x0, 16)
vadd.i32 q0, q0, q1
veor q4, q3, q0
vshl.u32 q3, q4, #16
vsri.u32 q3, q4, #16
veor q3, q3, q0
vrev32.16 q3, q3
// x2 += x3, x1 = rotl32(x1 ^ x2, 12)
vadd.i32 q2, q2, q3