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@xxxxxxxxxx>
---
crypto/aegis128-neon-inner.c | 89 +++++++++++++++++---
1 file changed, 75 insertions(+), 14 deletions(-)
diff --git a/crypto/aegis128-neon-inner.c b/crypto/aegis128-neon-inner.c
index 2a660ac1bc3a..cd1b3ad1d1f3 100644
--- a/crypto/aegis128-neon-inner.c
+++ b/crypto/aegis128-neon-inner.c
@@ -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);
--
2.17.1
