ghash_cpu.cpp

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/*
* Hook for CLMUL/PMULL/VPMSUM
* (C) 2013,2017,2019,2020 Jack Lloyd
*
* Botan is released under the Simplified BSD License (see license.txt)
*/
 
#include <botan/internal/ghash.h>
 
#include <botan/internal/isa_extn.h>
#include <botan/internal/simd_4x32.h>
#include <botan/internal/target_info.h>
#include <bit>
 
#if defined(BOTAN_SIMD_USE_SSSE3)
   #include <immintrin.h>
   #include <wmmintrin.h>
#endif
 
namespace Botan {
 
namespace {
 
BOTAN_FORCE_INLINE BOTAN_FN_ISA_SIMD_4X32 SIMD_4x32 reverse_vector(const SIMD_4x32& in) {
#if defined(BOTAN_SIMD_USE_SSSE3)
   const __m128i BSWAP_MASK = _mm_set_epi8(0, 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15);
   return SIMD_4x32(_mm_shuffle_epi8(in.raw(), BSWAP_MASK));
#elif defined(BOTAN_SIMD_USE_NEON)
   const uint8_t maskb[16] = {15, 14, 13, 12, 11, 10, 9, 8, 7, 6, 5, 4, 3, 2, 1, 0};
   const uint8x16_t mask = vld1q_u8(maskb);
   return SIMD_4x32(vreinterpretq_u32_u8(vqtbl1q_u8(vreinterpretq_u8_u32(in.raw()), mask)));
#elif defined(BOTAN_SIMD_USE_ALTIVEC)
   const __vector unsigned char mask = {15, 14, 13, 12, 11, 10, 9, 8, 7, 6, 5, 4, 3, 2, 1, 0};
   return SIMD_4x32(vec_perm(in.raw(), in.raw(), mask));
#endif
}
 
template <int M>
BOTAN_FORCE_INLINE BOTAN_FN_ISA_CLMUL SIMD_4x32 clmul(const SIMD_4x32& H, const SIMD_4x32& x) {
   static_assert(M == 0x00 || M == 0x01 || M == 0x10 || M == 0x11, "Valid clmul mode");
 
#if defined(BOTAN_SIMD_USE_SSSE3)
   return SIMD_4x32(_mm_clmulepi64_si128(x.raw(), H.raw(), M));
#elif defined(BOTAN_SIMD_USE_NEON)
   const uint64_t a = vgetq_lane_u64(vreinterpretq_u64_u32(x.raw()), M & 0x01);
   const uint64_t b = vgetq_lane_u64(vreinterpretq_u64_u32(H.raw()), (M & 0x10) >> 4);
 
   #if defined(BOTAN_BUILD_COMPILER_IS_MSVC)
   __n64 a1 = {a}, b1 = {b};
   return SIMD_4x32(vmull_p64(a1, b1));
   #else
   return SIMD_4x32(reinterpret_cast<uint32x4_t>(vmull_p64(a, b)));
   #endif
 
#elif defined(BOTAN_SIMD_USE_ALTIVEC)
   const SIMD_4x32 mask_lo = SIMD_4x32(0, 0, 0xFFFFFFFF, 0xFFFFFFFF);
   constexpr uint8_t flip = (std::endian::native == std::endian::big) ? 0x11 : 0x00;
 
   SIMD_4x32 i1 = x;
   SIMD_4x32 i2 = H;
 
   if constexpr(std::endian::native == std::endian::big) {
      i1 = reverse_vector(i1).bswap();
      i2 = reverse_vector(i2).bswap();
   }
 
   if constexpr(M == (0x11 ^ flip)) {
      i1 &= mask_lo;
      i2 &= mask_lo;
   } else if constexpr(M == (0x10 ^ flip)) {
      i1 = i1.shift_elems_left<2>();
   } else if constexpr(M == (0x01 ^ flip)) {
      i2 = i2.shift_elems_left<2>();
   } else if constexpr(M == (0x00 ^ flip)) {
      i1 = mask_lo.andc(i1);
      i2 = mask_lo.andc(i2);
   }
 
   auto i1v = reinterpret_cast<__vector unsigned long long>(i1.raw());
   auto i2v = reinterpret_cast<__vector unsigned long long>(i2.raw());
 
   #if BOTAN_COMPILER_HAS_BUILTIN(__builtin_crypto_vpmsumd)
   auto rv = __builtin_crypto_vpmsumd(i1v, i2v);
   #else
   auto rv = __builtin_altivec_crypto_vpmsumd(i1v, i2v);
   #endif
 
   auto z = SIMD_4x32(reinterpret_cast<__vector unsigned int>(rv));
 
   if constexpr(std::endian::native == std::endian::big) {
      z = reverse_vector(z).bswap();
   }
 
   return z;
#endif
}
 
inline SIMD_4x32 BOTAN_FN_ISA_CLMUL gcm_reduce(const SIMD_4x32& B0, const SIMD_4x32& B1) {
   SIMD_4x32 X0 = B1.shr<31>();
   SIMD_4x32 X1 = B1.shl<1>();
   SIMD_4x32 X2 = B0.shr<31>();
   SIMD_4x32 X3 = B0.shl<1>();
 
   X3 |= X0.shift_elems_right<3>();
   X3 |= X2.shift_elems_left<1>();
   X1 |= X0.shift_elems_left<1>();
 
   X0 = X1.shl<31>() ^ X1.shl<30>() ^ X1.shl<25>();
 
   X1 ^= X0.shift_elems_left<3>();
 
   X0 = X1 ^ X3 ^ X0.shift_elems_right<1>();
   X0 ^= X1.shr<7>() ^ X1.shr<2>() ^ X1.shr<1>();
   return X0;
}
 
inline SIMD_4x32 BOTAN_FN_ISA_CLMUL gcm_multiply(const SIMD_4x32& H, const SIMD_4x32& x) {
   SIMD_4x32 T0 = clmul<0x11>(H, x);
   SIMD_4x32 T1 = clmul<0x10>(H, x);
   SIMD_4x32 T2 = clmul<0x01>(H, x);
   SIMD_4x32 T3 = clmul<0x00>(H, x);
 
   T1 ^= T2;
   T0 ^= T1.shift_elems_right<2>();
   T3 ^= T1.shift_elems_left<2>();
 
   return gcm_reduce(T0, T3);
}
 
inline SIMD_4x32 BOTAN_FN_ISA_CLMUL gcm_multiply_x4(const SIMD_4x32& H1,
                                                    const SIMD_4x32& H2,
                                                    const SIMD_4x32& H3,
                                                    const SIMD_4x32& H4,
                                                    const SIMD_4x32& X1,
                                                    const SIMD_4x32& X2,
                                                    const SIMD_4x32& X3,
                                                    const SIMD_4x32& X4) {
   /*
   * Mutiply with delayed reduction, algorithm by Krzysztof Jankowski
   * and Pierre Laurent of Intel
   */
 
   const SIMD_4x32 lo = (clmul<0x00>(H1, X1) ^ clmul<0x00>(H2, X2)) ^ (clmul<0x00>(H3, X3) ^ clmul<0x00>(H4, X4));
 
   const SIMD_4x32 hi = (clmul<0x11>(H1, X1) ^ clmul<0x11>(H2, X2)) ^ (clmul<0x11>(H3, X3) ^ clmul<0x11>(H4, X4));
 
   SIMD_4x32 T;
 
   T ^= clmul<0x00>(H1 ^ H1.shift_elems_right<2>(), X1 ^ X1.shift_elems_right<2>());
   T ^= clmul<0x00>(H2 ^ H2.shift_elems_right<2>(), X2 ^ X2.shift_elems_right<2>());
   T ^= clmul<0x00>(H3 ^ H3.shift_elems_right<2>(), X3 ^ X3.shift_elems_right<2>());
   T ^= clmul<0x00>(H4 ^ H4.shift_elems_right<2>(), X4 ^ X4.shift_elems_right<2>());
   T ^= lo;
   T ^= hi;
 
   return gcm_reduce(hi ^ T.shift_elems_right<2>(), lo ^ T.shift_elems_left<2>());
}
 
}  // namespace
 
void BOTAN_FN_ISA_CLMUL GHASH::ghash_precompute_cpu(const uint8_t H_bytes[16], uint64_t H_pow[4 * 2]) {
   const SIMD_4x32 H1 = reverse_vector(SIMD_4x32::load_le(H_bytes));
   const SIMD_4x32 H2 = gcm_multiply(H1, H1);
   const SIMD_4x32 H3 = gcm_multiply(H1, H2);
   const SIMD_4x32 H4 = gcm_multiply(H2, H2);
 
   H1.store_le(H_pow);
   H2.store_le(H_pow + 2);
   H3.store_le(H_pow + 4);
   H4.store_le(H_pow + 6);
}
 
void BOTAN_FN_ISA_CLMUL GHASH::ghash_multiply_cpu(uint8_t x[16],
                                                  const uint64_t H_pow[8],
                                                  const uint8_t input[],
                                                  size_t blocks) {
   /*
   * Algorithms 1 and 5 from Intel's CLMUL guide
   */
   const SIMD_4x32 H1 = SIMD_4x32::load_le(H_pow);
 
   SIMD_4x32 a = reverse_vector(SIMD_4x32::load_le(x));
 
   if(blocks >= 4) {
      const SIMD_4x32 H2 = SIMD_4x32::load_le(H_pow + 2);
      const SIMD_4x32 H3 = SIMD_4x32::load_le(H_pow + 4);
      const SIMD_4x32 H4 = SIMD_4x32::load_le(H_pow + 6);
 
      while(blocks >= 4) {
         const SIMD_4x32 m0 = reverse_vector(SIMD_4x32::load_le(input));
         const SIMD_4x32 m1 = reverse_vector(SIMD_4x32::load_le(input + 16 * 1));
         const SIMD_4x32 m2 = reverse_vector(SIMD_4x32::load_le(input + 16 * 2));
         const SIMD_4x32 m3 = reverse_vector(SIMD_4x32::load_le(input + 16 * 3));
 
         a ^= m0;
         a = gcm_multiply_x4(H1, H2, H3, H4, m3, m2, m1, a);
 
         input += 4 * 16;
         blocks -= 4;
      }
   }
 
   for(size_t i = 0; i != blocks; ++i) {
      const SIMD_4x32 m = reverse_vector(SIMD_4x32::load_le(input + 16 * i));
 
      a ^= m;
      a = gcm_multiply(H1, a);
   }
 
   a = reverse_vector(a);
   a.store_le(x);
}
 
}  // namespace Botan