crypto: x86/aes-xts - optimize _compute_first_set_of_tweaks for AVX-512
Subsystems (2)
PATCH 1/1 crypto: x86/aes-xts - optimize _compute_first_set_of_tweaks for AVX-512
From: Eric Biggers <[email protected]>
Optimize the AVX-512 version of _compute_first_set_of_tweaks by using vectorized shifts to compute the first vector of tweak blocks, and by using byte-aligned shifts when multiplying by x^8.
AES-XTS performance on AMD Ryzen 9 9950X (Zen 5) improves by about 2% for 4096-byte messages or 6% for 512-byte messages. AES-XTS performance on Intel Sapphire Rapids improves by about 1% for 4096-byte messages or 3% for 512-byte messages. Code size decreases by 75 bytes which outweighs the increase in rodata size of 16 bytes.
Signed-off-by Eric Biggers <[email protected]>
---
This applies to current mainline (a52a3c18cdf369a7) plus the patch "crypto: x86/aes - drop the avx10_256 AES-XTS and AES-CTR code"
(https://lore.kernel.org/linux-crypto/[email protected]/)
arch/x86/crypto/aes-xts-avx-x86_64.S | 90 +++++++++++++++++++--------- 1 file changed, 62 insertions(+), 28 deletions(-)
arch/x86/crypto/aes-xts-avx-x86_64.S +62 -28
@@ -98,10 +98,21 @@ // // The high 64 bits of this value is just the internal carry bit that // exists when there's a carry out of the low 64 bits of the tweak. .quad 0x87, 1 + // These are the shift amounts that are needed when multiplying by [x^0, + // x^1, x^2, x^3] to compute the first vector of tweaks when VL=64. + // + // The right shifts by 64 are expected to zeroize the destination. + // 'vpsrlvq' is indeed defined to do that; i.e. it doesn't truncate the + // amount to 64 & 63 = 0 like the 'shr' scalar shift instruction would. +.Lrshift_amounts: + .byte 64, 64, 63, 63, 62, 62, 61, 61 +.Llshift_amounts: + .byte 0, 0, 1, 1, 2, 2, 3, 3 + // This table contains constants for vpshufb and vpblendvb, used to // handle variable byte shifts and blending during ciphertext stealing // on CPUs that don't support AVX512-style masking. .Lcts_permute_table: .byte 0x80, 0x80, 0x80, 0x80, 0x80, 0x80, 0x80, 0x80
@@ -292,56 +303,79 @@ .endm // Given the first XTS tweak at (TWEAK), compute the first set of tweaks and // store them in the vector registers TWEAK0-TWEAK3. Clobbers V0-V5. .macro _compute_first_set_of_tweaks - vmovdqu (TWEAK), TWEAK0_XMM - _vbroadcast128 .Lgf_poly(%rip), GF_POLY .if VL == 16 - // With VL=16, multiplying by x serially is fastest. + vmovdqu (TWEAK), TWEAK0_XMM + vmovdqu .Lgf_poly(%rip), GF_POLY _next_tweak TWEAK0, %xmm0, TWEAK1 _next_tweak TWEAK1, %xmm0, TWEAK2 _next_tweak TWEAK2, %xmm0, TWEAK3 -.else -.if VL == 32 - // Compute the second block of TWEAK0. +.elseif VL == 32 + vmovdqu (TWEAK), TWEAK0_XMM + vbroadcasti128 .Lgf_poly(%rip), GF_POLY + + // Compute the first vector of tweaks. _next_tweak TWEAK0_XMM, %xmm0, %xmm1 vinserti128 $1, %xmm1, TWEAK0, TWEAK0 -.elseif VL == 64 - // Compute the remaining blocks of TWEAK0. - _next_tweak TWEAK0_XMM, %xmm0, %xmm1 - _next_tweak %xmm1, %xmm0, %xmm2 - _next_tweak %xmm2, %xmm0, %xmm3 - vinserti32x4 $1, %xmm1, TWEAK0, TWEAK0 - vinserti32x4 $2, %xmm2, TWEAK0, TWEAK0 - vinserti32x4 $3, %xmm3, TWEAK0, TWEAK0 -.endif - // Compute TWEAK[1-3] from TWEAK0. - vpsrlq $64 - 1*VL/16, TWEAK0, V0 - vpsrlq $64 - 2*VL/16, TWEAK0, V2 - vpsrlq $64 - 3*VL/16, TWEAK0, V4 + + // Compute the next three vectors of tweaks: + // TWEAK1 = TWEAK0 * [x^2, x^2] + // TWEAK2 = TWEAK0 * [x^4, x^4] + // TWEAK3 = TWEAK0 * [x^6, x^6] + vpsrlq $64 - 2, TWEAK0, V0 + vpsrlq $64 - 4, TWEAK0, V2 + vpsrlq $64 - 6, TWEAK0, V4 vpclmulqdq $0x01, GF_POLY, V0, V1 vpclmulqdq $0x01, GF_POLY, V2, V3 vpclmulqdq $0x01, GF_POLY, V4, V5 vpslldq $8, V0, V0 vpslldq $8, V2, V2 vpslldq $8, V4, V4 - vpsllq $1*VL/16, TWEAK0, TWEAK1 - vpsllq $2*VL/16, TWEAK0, TWEAK2 - vpsllq $3*VL/16, TWEAK0, TWEAK3 -.if USE_AVX512 - vpternlogd $0x96, V0, V1, TWEAK1 - vpternlogd $0x96, V2, V3, TWEAK2 - vpternlogd $0x96, V4, V5, TWEAK3 -.else + vpsllq $2, TWEAK0, TWEAK1 + vpsllq $4, TWEAK0, TWEAK2 + vpsllq $6, TWEAK0, TWEAK3 vpxor V0, TWEAK1, TWEAK1 vpxor V2, TWEAK2, TWEAK2 vpxor V4, TWEAK3, TWEAK3 vpxor V1, TWEAK1, TWEAK1 vpxor V3, TWEAK2, TWEAK2 vpxor V5, TWEAK3, TWEAK3 -.endif +.else + vbroadcasti32x4 (TWEAK), TWEAK0 + vbroadcasti32x4 .Lgf_poly(%rip), GF_POLY + + // Compute the first vector of tweaks: + // TWEAK0 = broadcast128(TWEAK) * [x^0, x^1, x^2, x^3] + vpmovzxbq .Lrshift_amounts(%rip), V4 + vpsrlvq V4, TWEAK0, V0 + vpclmulqdq $0x01, GF_POLY, V0, V1 + vpmovzxbq .Llshift_amounts(%rip), V4 + vpslldq $8, V0, V0 + vpsllvq V4, TWEAK0, TWEAK0 + vpternlogd $0x96, V0, V1, TWEAK0 + + // Compute the next three vectors of tweaks: + // TWEAK1 = TWEAK0 * [x^4, x^4, x^4, x^4] + // TWEAK2 = TWEAK0 * [x^8, x^8, x^8, x^8] + // TWEAK3 = TWEAK0 * [x^12, x^12, x^12, x^12] + // x^8 only needs byte-aligned shifts, so optimize accordingly. + vpsrlq $64 - 4, TWEAK0, V0 + vpsrldq $(64 - 8) / 8, TWEAK0, V2 + vpsrlq $64 - 12, TWEAK0, V4 + vpclmulqdq $0x01, GF_POLY, V0, V1 + vpclmulqdq $0x01, GF_POLY, V2, V3 + vpclmulqdq $0x01, GF_POLY, V4, V5 + vpslldq $8, V0, V0 + vpslldq $8, V4, V4 + vpsllq $4, TWEAK0, TWEAK1 + vpslldq $8 / 8, TWEAK0, TWEAK2 + vpsllq $12, TWEAK0, TWEAK3 + vpternlogd $0x96, V0, V1, TWEAK1 + vpxord V3, TWEAK2, TWEAK2 + vpternlogd $0x96, V4, V5, TWEAK3 .endif .endm // Do one step in computing the next set of tweaks using the method of just // multiplying by x repeatedly (the same method _next_tweak uses).
Signature · 1 line
2.49.0