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Do not use NEON for AES-CBC on aarch64

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Signed-off-by: Dave Rodgman <dave.rodgman@arm.com>
This commit is contained in:
Dave Rodgman 2023-06-14 18:58:48 +01:00
parent 906c63cf35
commit d05e7f1ab3
1 changed files with 20 additions and 3 deletions
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23
library/aes.c
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@ -1035,6 +1035,24 @@ int mbedtls_aes_crypt_ecb(mbedtls_aes_context *ctx,
}
#if defined(MBEDTLS_CIPHER_MODE_CBC)
#if defined(__ARM_NEON) && defined(__aarch64__)
/* Avoid using the NEON implementation of mbedtls_xor. Because of the dependency on
* the result for the next block in CBC, and the cost of transferring that data from
* NEON registers, it is faster to use the following on aarch64.
* For 32-bit arm, NEON should be faster. */
#define CBC_XOR_16(r, a, b) do { \
mbedtls_put_unaligned_uint64(r, \
mbedtls_get_unaligned_uint64(a) ^ \
mbedtls_get_unaligned_uint64(b)); \
mbedtls_put_unaligned_uint64(r + 8, \
mbedtls_get_unaligned_uint64(a + 8) ^ \
mbedtls_get_unaligned_uint64(b + 8)); \
} while (0)
#else
#define CBC_XOR_16(r, a, b) mbedtls_xor(r, a, b, 16)
#endif
/*
* AES-CBC buffer encryption/decryption
*/
@ -1077,8 +1095,7 @@ int mbedtls_aes_crypt_cbc(mbedtls_aes_context *ctx,
if (ret != 0) {
goto exit;
}
mbedtls_xor(output, output, iv, 16);
CBC_XOR_16(output, output, iv);
memcpy(iv, temp, 16);
@ -1088,7 +1105,7 @@ int mbedtls_aes_crypt_cbc(mbedtls_aes_context *ctx,
}
} else {
while (length > 0) {
mbedtls_xor(output, input, ivp, 16);
CBC_XOR_16(output, input, ivp);
ret = mbedtls_aes_crypt_ecb(ctx, mode, output, output);
if (ret != 0) {