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crypto: aegis128/neon - optimize tail block handling

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Avoid copying the tail block via a stack buffer if the total size
exceeds a single AEGIS block. In this case, we can use overlapping
loads and stores and NEON permutation instructions instead, which
leads to a modest performance improvement on some cores (< 5%),
and is slightly cleaner. Note that we still need to use a stack
buffer if the entire input is smaller than 16 bytes, given that
we cannot use 16 byte NEON loads and stores safely in this case.

Signed-off-by: Ard Biesheuvel <ardb@kernel.org>
Reviewed-by: Ondrej Mosnacek <omosnacek@gmail.com>
Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>
This commit is contained in:
Ard Biesheuvel 2020-11-17 14:32:12 +01:00 committed by Herbert Xu
parent 02685906d3
commit ad00d41b47
1 changed files with 75 additions and 14 deletions
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89
crypto/aegis128-neon-inner.c
View file

@ -20,7 +20,6 @@
extern int aegis128_have_aes_insn;
void *memcpy(void *dest, const void *src, size_t n);
void *memset(void *s, int c, size_t n);
struct aegis128_state {
uint8x16_t v[5];
@ -173,10 +172,46 @@ void crypto_aegis128_update_neon(void *state, const void *msg)
aegis128_save_state_neon(st, state);
}
#ifdef CONFIG_ARM
/*
* AArch32 does not provide these intrinsics natively because it does not
* implement the underlying instructions. AArch32 only provides 64-bit
* wide vtbl.8/vtbx.8 instruction, so use those instead.
*/
static uint8x16_t vqtbl1q_u8(uint8x16_t a, uint8x16_t b)
{
union {
uint8x16_t val;
uint8x8x2_t pair;
} __a = { a };
return vcombine_u8(vtbl2_u8(__a.pair, vget_low_u8(b)),
vtbl2_u8(__a.pair, vget_high_u8(b)));
}
static uint8x16_t vqtbx1q_u8(uint8x16_t v, uint8x16_t a, uint8x16_t b)
{
union {
uint8x16_t val;
uint8x8x2_t pair;
} __a = { a };
return vcombine_u8(vtbx2_u8(vget_low_u8(v), __a.pair, vget_low_u8(b)),
vtbx2_u8(vget_high_u8(v), __a.pair, vget_high_u8(b)));
}
#endif
static const uint8_t permute[] __aligned(64) = {
-1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1,
0, 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15,
-1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1,
};
void crypto_aegis128_encrypt_chunk_neon(void *state, void *dst, const void *src,
unsigned int size)
{
struct aegis128_state st = aegis128_load_state_neon(state);
const int short_input = size < AEGIS_BLOCK_SIZE;
uint8x16_t msg;
preload_sbox();
@ -186,7 +221,8 @@ void crypto_aegis128_encrypt_chunk_neon(void *state, void *dst, const void *src,
msg = vld1q_u8(src);
st = aegis128_update_neon(st, msg);
vst1q_u8(dst, msg ^ s);
msg ^= s;
vst1q_u8(dst, msg);
size -= AEGIS_BLOCK_SIZE;
src += AEGIS_BLOCK_SIZE;
@ -195,13 +231,26 @@ void crypto_aegis128_encrypt_chunk_neon(void *state, void *dst, const void *src,
if (size > 0) {
uint8x16_t s = st.v[1] ^ (st.v[2] & st.v[3]) ^ st.v[4];
uint8_t buf[AEGIS_BLOCK_SIZE] = {};
uint8_t buf[AEGIS_BLOCK_SIZE];
const void *in = src;
void *out = dst;
uint8x16_t m;
memcpy(buf, src, size);
msg = vld1q_u8(buf);
st = aegis128_update_neon(st, msg);
vst1q_u8(buf, msg ^ s);
memcpy(dst, buf, size);
if (__builtin_expect(short_input, 0))
in = out = memcpy(buf + AEGIS_BLOCK_SIZE - size, src, size);
m = vqtbl1q_u8(vld1q_u8(in + size - AEGIS_BLOCK_SIZE),
vld1q_u8(permute + 32 - size));
st = aegis128_update_neon(st, m);
vst1q_u8(out + size - AEGIS_BLOCK_SIZE,
vqtbl1q_u8(m ^ s, vld1q_u8(permute + size)));
if (__builtin_expect(short_input, 0))
memcpy(dst, out, size);
else
vst1q_u8(out - AEGIS_BLOCK_SIZE, msg);
}
aegis128_save_state_neon(st, state);
@ -211,6 +260,7 @@ void crypto_aegis128_decrypt_chunk_neon(void *state, void *dst, const void *src,
unsigned int size)
{
struct aegis128_state st = aegis128_load_state_neon(state);
const int short_input = size < AEGIS_BLOCK_SIZE;
uint8x16_t msg;
preload_sbox();
@ -228,14 +278,25 @@ void crypto_aegis128_decrypt_chunk_neon(void *state, void *dst, const void *src,
if (size > 0) {
uint8x16_t s = st.v[1] ^ (st.v[2] & st.v[3]) ^ st.v[4];
uint8_t buf[AEGIS_BLOCK_SIZE];
const void *in = src;
void *out = dst;
uint8x16_t m;
vst1q_u8(buf, s);
memcpy(buf, src, size);
msg = vld1q_u8(buf) ^ s;
vst1q_u8(buf, msg);
memcpy(dst, buf, size);
if (__builtin_expect(short_input, 0))
in = out = memcpy(buf + AEGIS_BLOCK_SIZE - size, src, size);
st = aegis128_update_neon(st, msg);
m = s ^ vqtbx1q_u8(s, vld1q_u8(in + size - AEGIS_BLOCK_SIZE),
vld1q_u8(permute + 32 - size));
st = aegis128_update_neon(st, m);
vst1q_u8(out + size - AEGIS_BLOCK_SIZE,
vqtbl1q_u8(m, vld1q_u8(permute + size)));
if (__builtin_expect(short_input, 0))
memcpy(dst, out, size);
else
vst1q_u8(out - AEGIS_BLOCK_SIZE, msg);
}
aegis128_save_state_neon(st, state);