crypto: arm64/aes-cts-cbc-ce - performance tweak

Optimize away one of the tbl instructions in the decryption path,
which turns out to be unnecessary.

Signed-off-by: Ard Biesheuvel <ard.biesheuvel@linaro.org>
Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>

diff --git a/arch/arm64/crypto/aes-modes.S b/arch/arm64/crypto/aes-modes.S
index 2879f030a749efdb7baf2b87db6be147afced4c4..38cd5a2091a8c276e186481e5a6335175d09171d 100644 (file)
--- a/arch/arm64/crypto/aes-modes.S
+++ b/arch/arm64/crypto/aes-modes.S
@@ -293,12 +293,11 @@ AES_ENTRY(aes_cbc_cts_decrypt)
        ld1             {v5.16b}, [x5]                  /* get iv */
        dec_prepare     w3, x2, x6
 
-       tbl             v2.16b, {v1.16b}, v4.16b
        decrypt_block   v0, w3, x2, x6, w7
-       eor             v2.16b, v2.16b, v0.16b
+       tbl             v2.16b, {v0.16b}, v3.16b
+       eor             v2.16b, v2.16b, v1.16b
 
        tbx             v0.16b, {v1.16b}, v4.16b
-       tbl             v2.16b, {v2.16b}, v3.16b
        decrypt_block   v0, w3, x2, x6, w7
        eor             v0.16b, v0.16b, v5.16b          /* xor with iv */