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crypto: arm64/aes-neon-ctr - improve handling of single tail block

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Instead of falling back to C code to do a memcpy of the output of the
last block, handle this in the asm code directly if possible, which is
the case if the entire input is longer than 16 bytes.

Cc: Nathan Huckleberry <nhuck@google.com>
Cc: Eric Biggers <ebiggers@google.com>
Signed-off-by: Ard Biesheuvel <ardb@kernel.org>
Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>
This commit is contained in:
Ard Biesheuvel 2022-01-27 10:52:11 +01:00 committed by Herbert Xu
parent e236ab0d43
commit 8daa399ede
2 changed files with 20 additions and 19 deletions
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21
arch/arm64/crypto/aes-glue.c
View File

@ -24,7 +24,6 @@
#ifdef USE_V8_CRYPTO_EXTENSIONS
#define MODE "ce"
#define PRIO 300
#define STRIDE 5
#define aes_expandkey ce_aes_expandkey
#define aes_ecb_encrypt ce_aes_ecb_encrypt
#define aes_ecb_decrypt ce_aes_ecb_decrypt
@ -42,7 +41,6 @@ MODULE_DESCRIPTION("AES-ECB/CBC/CTR/XTS using ARMv8 Crypto Extensions");
#else
#define MODE "neon"
#define PRIO 200
#define STRIDE 4
#define aes_ecb_encrypt neon_aes_ecb_encrypt
#define aes_ecb_decrypt neon_aes_ecb_decrypt
#define aes_cbc_encrypt neon_aes_cbc_encrypt
@ -89,7 +87,7 @@ asmlinkage void aes_cbc_cts_decrypt(u8 out[], u8 const in[], u32 const rk[],
int rounds, int bytes, u8 const iv[]);
asmlinkage void aes_ctr_encrypt(u8 out[], u8 const in[], u32 const rk[],
int rounds, int bytes, u8 ctr[], u8 finalbuf[]);
int rounds, int bytes, u8 ctr[]);
asmlinkage void aes_xts_encrypt(u8 out[], u8 const in[], u32 const rk1[],
int rounds, int bytes, u32 const rk2[], u8 iv[],
@ -458,26 +456,21 @@ static int __maybe_unused ctr_encrypt(struct skcipher_request *req)
unsigned int nbytes = walk.nbytes;
u8 *dst = walk.dst.virt.addr;
u8 buf[AES_BLOCK_SIZE];
unsigned int tail;
if (unlikely(nbytes < AES_BLOCK_SIZE))
src = memcpy(buf, src, nbytes);
src = dst = memcpy(buf + sizeof(buf) - nbytes,
src, nbytes);
else if (nbytes < walk.total)
nbytes &= ~(AES_BLOCK_SIZE - 1);
kernel_neon_begin();
aes_ctr_encrypt(dst, src, ctx->key_enc, rounds, nbytes,
walk.iv, buf);
walk.iv);
kernel_neon_end();
tail = nbytes % (STRIDE * AES_BLOCK_SIZE);
if (tail > 0 && tail < AES_BLOCK_SIZE)
/*
* The final partial block could not be returned using
* an overlapping store, so it was passed via buf[]
* instead.
*/
memcpy(dst + nbytes - tail, buf, tail);
if (unlikely(nbytes < AES_BLOCK_SIZE))
memcpy(walk.dst.virt.addr,
buf + sizeof(buf) - nbytes, nbytes);
err = skcipher_walk_done(&walk, walk.nbytes - nbytes);
}

18
arch/arm64/crypto/aes-modes.S
View File

@ -321,7 +321,7 @@ AES_FUNC_END(aes_cbc_cts_decrypt)
/*
* aes_ctr_encrypt(u8 out[], u8 const in[], u8 const rk[], int rounds,
* int bytes, u8 ctr[], u8 finalbuf[])
* int bytes, u8 ctr[])
*/
AES_FUNC_START(aes_ctr_encrypt)
@ -414,8 +414,8 @@ ST5( st1 {v4.16b}, [x0], #16 )
.Lctrtail:
/* XOR up to MAX_STRIDE * 16 - 1 bytes of in/output with v0 ... v3/v4 */
mov x16, #16
ands x13, x4, #0xf
csel x13, x13, x16, ne
ands x6, x4, #0xf
csel x13, x6, x16, ne
ST5( cmp w4, #64 - (MAX_STRIDE << 4) )
ST5( csel x14, x16, xzr, gt )
@ -424,10 +424,10 @@ ST5( csel x14, x16, xzr, gt )
cmp w4, #32 - (MAX_STRIDE << 4)
csel x16, x16, xzr, gt
cmp w4, #16 - (MAX_STRIDE << 4)
ble .Lctrtail1x
adr_l x12, .Lcts_permute_table
add x12, x12, x13
ble .Lctrtail1x
ST5( ld1 {v5.16b}, [x1], x14 )
ld1 {v6.16b}, [x1], x15
@ -462,11 +462,19 @@ ST5( st1 {v5.16b}, [x0], x14 )
b .Lctrout
.Lctrtail1x:
csel x0, x0, x6, eq // use finalbuf if less than a full block
sub x7, x6, #16
csel x6, x6, x7, eq
add x1, x1, x6
add x0, x0, x6
ld1 {v5.16b}, [x1]
ld1 {v6.16b}, [x0]
ST5( mov v3.16b, v4.16b )
encrypt_block v3, w3, x2, x8, w7
ld1 {v10.16b-v11.16b}, [x12]
tbl v3.16b, {v3.16b}, v10.16b
sshr v11.16b, v11.16b, #7
eor v5.16b, v5.16b, v3.16b
bif v5.16b, v6.16b, v11.16b
st1 {v5.16b}, [x0]
b .Lctrout
AES_FUNC_END(aes_ctr_encrypt)