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Improved GHASH pclmul implementation (parallel processing of four blocks, +70% speed).
This commit is contained in:
Thomas Pornin
parent
db8f1b6645
commit
98432a0a30
@ -42,164 +42,266 @@
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#include <intrin.h>
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#include <intrin.h>
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#endif
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#endif
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/*
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* GHASH is defined over elements of GF(2^128) with "full little-endian"
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* representation: leftmost byte is least significant, and, within each
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* byte, leftmost _bit_ is least significant. The natural ordering in
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* x86 is "mixed little-endian": bytes are ordered from least to most
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* significant, but bits within a byte are in most-to-least significant
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* order. Going to full little-endian representation would require
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* reversing bits within each byte, which is doable but expensive.
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*
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* Instead, we go to full big-endian representation, by swapping bytes
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* around, which is done with a single _mm_shuffle_epi8() opcode (it
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* comes with SSSE3; all CPU that offer pclmulqdq also have SSSE3). We
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* can use a full big-endian representation because in a carryless
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* multiplication, we have a nice bit reversal property:
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*
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* rev_128(x) * rev_128(y) = rev_255(x * y)
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*
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* So by using full big-endian, we still get the right result, except
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* that it is right-shifted by 1 bit. The left-shift is relatively
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* inexpensive, and it can be mutualised.
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*
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*
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* Since SSE2 opcodes do not have facilities for shitfting full 128-bit
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* values with bit precision, we have to break down values into 64-bit
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* chunks. We number chunks from 0 to 3 in left to right order.
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*/
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/*
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* From a 128-bit value kw, compute kx as the XOR of the two 64-bit
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* halves of kw (into the right half of kx; left half is unspecified).
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*/
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#define BK(kw, kx) do { \
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kx = _mm_xor_si128(kw, _mm_shuffle_epi32(kw, 0x0E)); \
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} while (0)
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/*
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* Combine two 64-bit values (k0:k1) into a 128-bit (kw) value and
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* the XOR of the two values (kx).
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*/
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#define PBK(k0, k1, kw, kx) do { \
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kw = _mm_unpacklo_epi64(k1, k0); \
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kx = _mm_xor_si128(k0, k1); \
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} while (0)
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/*
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* Left-shift by 1 bit a 256-bit value (in four 64-bit words).
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*/
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#define SL_256(x0, x1, x2, x3) do { \
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x0 = _mm_or_si128( \
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_mm_slli_epi64(x0, 1), \
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_mm_srli_epi64(x1, 63)); \
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x1 = _mm_or_si128( \
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_mm_slli_epi64(x1, 1), \
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_mm_srli_epi64(x2, 63)); \
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x2 = _mm_or_si128( \
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_mm_slli_epi64(x2, 1), \
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_mm_srli_epi64(x3, 63)); \
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x3 = _mm_slli_epi64(x3, 1); \
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} while (0)
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/*
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* Perform reduction in GF(2^128). The 256-bit value is in x0..x3;
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* result is written in x0..x1.
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*/
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#define REDUCE_F128(x0, x1, x2, x3) do { \
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x1 = _mm_xor_si128( \
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x1, \
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_mm_xor_si128( \
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_mm_xor_si128( \
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x3, \
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_mm_srli_epi64(x3, 1)), \
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_mm_xor_si128( \
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_mm_srli_epi64(x3, 2), \
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_mm_srli_epi64(x3, 7)))); \
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x2 = _mm_xor_si128( \
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_mm_xor_si128( \
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x2, \
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_mm_slli_epi64(x3, 63)), \
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_mm_xor_si128( \
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_mm_slli_epi64(x3, 62), \
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_mm_slli_epi64(x3, 57))); \
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x0 = _mm_xor_si128( \
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x0, \
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_mm_xor_si128( \
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_mm_xor_si128( \
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x2, \
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_mm_srli_epi64(x2, 1)), \
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_mm_xor_si128( \
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_mm_srli_epi64(x2, 2), \
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_mm_srli_epi64(x2, 7)))); \
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x1 = _mm_xor_si128( \
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_mm_xor_si128( \
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x1, \
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_mm_slli_epi64(x2, 63)), \
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_mm_xor_si128( \
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_mm_slli_epi64(x2, 62), \
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_mm_slli_epi64(x2, 57))); \
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} while (0)
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/*
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* Square value kw into (dw,dx).
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*/
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#define SQUARE_F128(kw, dw, dx) do { \
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__m128i z0, z1, z2, z3; \
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z1 = _mm_clmulepi64_si128(kw, kw, 0x11); \
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z3 = _mm_clmulepi64_si128(kw, kw, 0x00); \
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z0 = _mm_shuffle_epi32(z1, 0x0E); \
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z2 = _mm_shuffle_epi32(z3, 0x0E); \
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SL_256(z0, z1, z2, z3); \
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REDUCE_F128(z0, z1, z2, z3); \
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PBK(z0, z1, dw, dx); \
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} while (0)
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/* see bearssl_hash.h */
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/* see bearssl_hash.h */
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BR_TARGET("ssse3,pclmul")
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BR_TARGET("ssse3,pclmul")
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void
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void
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br_ghash_pclmul(void *y, const void *h, const void *data, size_t len)
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br_ghash_pclmul(void *y, const void *h, const void *data, size_t len)
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{
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{
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/*
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const unsigned char *buf1, *buf2;
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* TODO: loop below processes one 16-bit word at a time. We
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unsigned char tmp[64];
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* could parallelize, using:
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size_t num4, num1;
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* ((y+x0)*h+x1)*h = (y+x0)*(h^2) + x1*h
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__m128i yw, h1w, h1x;
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* i.e. precompute h^2, then handle two words at a time, mostly
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* in parallel (this may extend to more words as well...).
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*/
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const unsigned char *buf;
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__m128i yx, hx;
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__m128i h0, h1, h2;
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__m128i byteswap_index;
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__m128i byteswap_index;
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byteswap_index = _mm_set_epi8(
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0, 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15);
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yx = _mm_loadu_si128(y);
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hx = _mm_loadu_si128(h);
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yx = _mm_shuffle_epi8(yx, byteswap_index);
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hx = _mm_shuffle_epi8(hx, byteswap_index);
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/*
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/*
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* We byte-swap y and h for full big-endian interpretation
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* We split data into two chunks. First chunk starts at buf1
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* (see below).
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* and contains num4 blocks of 64-byte values. Second chunk
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* starts at buf2 and contains num1 blocks of 16-byte values.
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* We want the first chunk to be as large as possible.
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*/
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*/
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buf1 = data;
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h0 = hx;
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num4 = len >> 6;
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h1 = _mm_shuffle_epi32(hx, 0x0E);
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len &= 63;
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h2 = _mm_xor_si128(h0, h1);
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buf2 = buf1 + (num4 << 6);
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num1 = (len + 15) >> 4;
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buf = data;
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if ((len & 15) != 0) {
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while (len > 0) {
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memcpy(tmp, buf2, len);
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__m128i x;
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memset(tmp + len, 0, (num1 << 4) - len);
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__m128i t0, t1, t2, v0, v1, v2, v3;
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buf2 = tmp;
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__m128i y0, y1, y2;
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/*
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* Load next 128-bit word. If there are not enough bytes
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* for the next word, we pad it with zeros (as per the
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* API for this function; it's also what is useful for
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* implementation of GCM).
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*/
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if (len >= 16) {
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x = _mm_loadu_si128((const void *)buf);
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buf += 16;
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len -= 16;
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} else {
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unsigned char tmp[16];
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memcpy(tmp, buf, len);
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memset(tmp + len, 0, (sizeof tmp) - len);
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x = _mm_loadu_si128((void *)tmp);
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len = 0;
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}
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/*
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* Specification of GCM is basically "full little-endian",
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* i.e. leftmost bit is most significant; but decoding
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* performed by _mm_loadu_si128 is "mixed endian" (leftmost
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* _byte_ is least significant, but within each byte, the
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* leftmost _bit_ is most significant). We could reverse
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* bits in each byte; however, it is more efficient to
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* swap the bytes and thus emulate full big-endian
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* decoding.
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*
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* Big-endian works here because multiplication in
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* GF[2](X) is "carry-less", thereby allowing reversal:
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* if rev_n(x) consists in reversing the order of bits
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* in x, then:
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* rev_128(A)*rev_128(B) = rev_255(A*B)
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* so we can compute A*B by using rev_128(A) and rev_128(B),
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* and an extra shift at the end (because 255 != 256). Bit
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* reversal is exactly what happens when converting from
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* full little-endian to full big-endian.
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*/
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x = _mm_shuffle_epi8(x, byteswap_index);
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yx = _mm_xor_si128(yx, x);
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/*
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* We want the product to be broken down into four
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* 64-bit values, because there is no SSE* opcode that
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* can do a shift on a 128-bit value.
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*/
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y0 = yx;
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y1 = _mm_shuffle_epi32(yx, 0x0E);
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y2 = _mm_xor_si128(y0, y1);
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t0 = _mm_clmulepi64_si128(y0, h0, 0x00);
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t1 = _mm_clmulepi64_si128(yx, hx, 0x11);
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t2 = _mm_clmulepi64_si128(y2, h2, 0x00);
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t2 = _mm_xor_si128(t2, _mm_xor_si128(t0, t1));
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v0 = t0;
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v1 = _mm_xor_si128(_mm_shuffle_epi32(t0, 0x0E), t2);
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v2 = _mm_xor_si128(t1, _mm_shuffle_epi32(t2, 0x0E));
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v3 = _mm_shuffle_epi32(t1, 0x0E);
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/*
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* Do the corrective 1-bit shift (255->256).
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*/
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v3 = _mm_or_si128(
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_mm_slli_epi64(v3, 1),
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_mm_srli_epi64(v2, 63));
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v2 = _mm_or_si128(
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_mm_slli_epi64(v2, 1),
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_mm_srli_epi64(v1, 63));
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v1 = _mm_or_si128(
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_mm_slli_epi64(v1, 1),
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_mm_srli_epi64(v0, 63));
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v0 = _mm_slli_epi64(v0, 1);
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/*
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* Perform polynomial reduction into GF(2^128).
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*/
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v2 = _mm_xor_si128(
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v2,
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_mm_xor_si128(
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_mm_xor_si128(
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v0,
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_mm_srli_epi64(v0, 1)),
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_mm_xor_si128(
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_mm_srli_epi64(v0, 2),
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_mm_srli_epi64(v0, 7))));
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v1 = _mm_xor_si128(
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_mm_xor_si128(
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v1,
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_mm_slli_epi64(v0, 63)),
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_mm_xor_si128(
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_mm_slli_epi64(v0, 62),
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_mm_slli_epi64(v0, 57)));
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v3 = _mm_xor_si128(
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v3,
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_mm_xor_si128(
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_mm_xor_si128(
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v1,
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_mm_srli_epi64(v1, 1)),
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_mm_xor_si128(
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_mm_srli_epi64(v1, 2),
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_mm_srli_epi64(v1, 7))));
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v2 = _mm_xor_si128(
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_mm_xor_si128(
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v2,
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_mm_slli_epi64(v1, 63)),
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_mm_xor_si128(
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_mm_slli_epi64(v1, 62),
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_mm_slli_epi64(v1, 57)));
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/*
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* We reduced toward the high words (v2 and v3), which
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* are the new value for y.
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*/
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yx = _mm_unpacklo_epi64(v2, v3);
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}
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}
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yx = _mm_shuffle_epi8(yx, byteswap_index);
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/*
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_mm_storeu_si128(y, yx);
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* Constant value to perform endian conversion.
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*/
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byteswap_index = _mm_set_epi8(
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0, 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15);
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/*
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* Load y and h.
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*/
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yw = _mm_loadu_si128(y);
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h1w = _mm_loadu_si128(h);
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yw = _mm_shuffle_epi8(yw, byteswap_index);
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h1w = _mm_shuffle_epi8(h1w, byteswap_index);
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BK(h1w, h1x);
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if (num4 > 0) {
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__m128i h2w, h2x, h3w, h3x, h4w, h4x;
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__m128i t0, t1, t2, t3;
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/*
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* Compute h2 = h^2.
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*/
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SQUARE_F128(h1w, h2w, h2x);
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/*
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* Compute h3 = h^3 = h*(h^2).
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*/
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t1 = _mm_clmulepi64_si128(h1w, h2w, 0x11);
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t3 = _mm_clmulepi64_si128(h1w, h2w, 0x00);
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t2 = _mm_xor_si128(_mm_clmulepi64_si128(h1x, h2x, 0x00),
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_mm_xor_si128(t1, t3));
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t0 = _mm_shuffle_epi32(t1, 0x0E);
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t1 = _mm_xor_si128(t1, _mm_shuffle_epi32(t2, 0x0E));
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t2 = _mm_xor_si128(t2, _mm_shuffle_epi32(t3, 0x0E));
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SL_256(t0, t1, t2, t3);
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REDUCE_F128(t0, t1, t2, t3);
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PBK(t0, t1, h3w, h3x);
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/*
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* Compute h4 = h^4 = (h^2)^2.
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*/
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SQUARE_F128(h2w, h4w, h4x);
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while (num4 -- > 0) {
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__m128i aw0, aw1, aw2, aw3;
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__m128i ax0, ax1, ax2, ax3;
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aw0 = _mm_loadu_si128((void *)(buf1 + 0));
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aw1 = _mm_loadu_si128((void *)(buf1 + 16));
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aw2 = _mm_loadu_si128((void *)(buf1 + 32));
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aw3 = _mm_loadu_si128((void *)(buf1 + 48));
|
||||||
|
aw0 = _mm_shuffle_epi8(aw0, byteswap_index);
|
||||||
|
aw1 = _mm_shuffle_epi8(aw1, byteswap_index);
|
||||||
|
aw2 = _mm_shuffle_epi8(aw2, byteswap_index);
|
||||||
|
aw3 = _mm_shuffle_epi8(aw3, byteswap_index);
|
||||||
|
buf1 += 64;
|
||||||
|
|
||||||
|
aw0 = _mm_xor_si128(aw0, yw);
|
||||||
|
BK(aw1, ax1);
|
||||||
|
BK(aw2, ax2);
|
||||||
|
BK(aw3, ax3);
|
||||||
|
BK(aw0, ax0);
|
||||||
|
|
||||||
|
t1 = _mm_xor_si128(
|
||||||
|
_mm_xor_si128(
|
||||||
|
_mm_clmulepi64_si128(aw0, h4w, 0x11),
|
||||||
|
_mm_clmulepi64_si128(aw1, h3w, 0x11)),
|
||||||
|
_mm_xor_si128(
|
||||||
|
_mm_clmulepi64_si128(aw2, h2w, 0x11),
|
||||||
|
_mm_clmulepi64_si128(aw3, h1w, 0x11)));
|
||||||
|
t3 = _mm_xor_si128(
|
||||||
|
_mm_xor_si128(
|
||||||
|
_mm_clmulepi64_si128(aw0, h4w, 0x00),
|
||||||
|
_mm_clmulepi64_si128(aw1, h3w, 0x00)),
|
||||||
|
_mm_xor_si128(
|
||||||
|
_mm_clmulepi64_si128(aw2, h2w, 0x00),
|
||||||
|
_mm_clmulepi64_si128(aw3, h1w, 0x00)));
|
||||||
|
t2 = _mm_xor_si128(
|
||||||
|
_mm_xor_si128(
|
||||||
|
_mm_clmulepi64_si128(ax0, h4x, 0x00),
|
||||||
|
_mm_clmulepi64_si128(ax1, h3x, 0x00)),
|
||||||
|
_mm_xor_si128(
|
||||||
|
_mm_clmulepi64_si128(ax2, h2x, 0x00),
|
||||||
|
_mm_clmulepi64_si128(ax3, h1x, 0x00)));
|
||||||
|
t2 = _mm_xor_si128(t2, _mm_xor_si128(t1, t3));
|
||||||
|
t0 = _mm_shuffle_epi32(t1, 0x0E);
|
||||||
|
t1 = _mm_xor_si128(t1, _mm_shuffle_epi32(t2, 0x0E));
|
||||||
|
t2 = _mm_xor_si128(t2, _mm_shuffle_epi32(t3, 0x0E));
|
||||||
|
SL_256(t0, t1, t2, t3);
|
||||||
|
REDUCE_F128(t0, t1, t2, t3);
|
||||||
|
yw = _mm_unpacklo_epi64(t1, t0);
|
||||||
|
}
|
||||||
|
}
|
||||||
|
|
||||||
|
while (num1 -- > 0) {
|
||||||
|
__m128i aw, ax;
|
||||||
|
__m128i t0, t1, t2, t3;
|
||||||
|
|
||||||
|
aw = _mm_loadu_si128((void *)buf2);
|
||||||
|
aw = _mm_shuffle_epi8(aw, byteswap_index);
|
||||||
|
buf2 += 16;
|
||||||
|
|
||||||
|
aw = _mm_xor_si128(aw, yw);
|
||||||
|
BK(aw, ax);
|
||||||
|
|
||||||
|
t1 = _mm_clmulepi64_si128(aw, h1w, 0x11);
|
||||||
|
t3 = _mm_clmulepi64_si128(aw, h1w, 0x00);
|
||||||
|
t2 = _mm_clmulepi64_si128(ax, h1x, 0x00);
|
||||||
|
t2 = _mm_xor_si128(t2, _mm_xor_si128(t1, t3));
|
||||||
|
t0 = _mm_shuffle_epi32(t1, 0x0E);
|
||||||
|
t1 = _mm_xor_si128(t1, _mm_shuffle_epi32(t2, 0x0E));
|
||||||
|
t2 = _mm_xor_si128(t2, _mm_shuffle_epi32(t3, 0x0E));
|
||||||
|
SL_256(t0, t1, t2, t3);
|
||||||
|
REDUCE_F128(t0, t1, t2, t3);
|
||||||
|
yw = _mm_unpacklo_epi64(t1, t0);
|
||||||
|
}
|
||||||
|
|
||||||
|
yw = _mm_shuffle_epi8(yw, byteswap_index);
|
||||||
|
_mm_storeu_si128(y, yw);
|
||||||
}
|
}
|
||||||
|
|
||||||
/*
|
/*
|
||||||
|
|||||||
Loading…
x
Reference in New Issue
Block a user