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Diffstat (limited to 'arch/s390/crypto/crc32le-vx.c')
| -rw-r--r-- | arch/s390/crypto/crc32le-vx.c | 240 |
1 files changed, 240 insertions, 0 deletions
diff --git a/arch/s390/crypto/crc32le-vx.c b/arch/s390/crypto/crc32le-vx.c new file mode 100644 index 00000000000000..2f629f394df750 --- /dev/null +++ b/arch/s390/crypto/crc32le-vx.c @@ -0,0 +1,240 @@ +/* SPDX-License-Identifier: GPL-2.0 */ +/* + * Hardware-accelerated CRC-32 variants for Linux on z Systems + * + * Use the z/Architecture Vector Extension Facility to accelerate the + * computing of bitreflected CRC-32 checksums for IEEE 802.3 Ethernet + * and Castagnoli. + * + * This CRC-32 implementation algorithm is bitreflected and processes + * the least-significant bit first (Little-Endian). + * + * Copyright IBM Corp. 2015 + * Author(s): Hendrik Brueckner <brueckner@linux.vnet.ibm.com> + */ + +#include <linux/types.h> +#include <asm/fpu.h> +#include "crc32-vx.h" + +/* Vector register range containing CRC-32 constants */ +#define CONST_PERM_LE2BE 9 +#define CONST_R2R1 10 +#define CONST_R4R3 11 +#define CONST_R5 12 +#define CONST_RU_POLY 13 +#define CONST_CRC_POLY 14 + +/* + * The CRC-32 constant block contains reduction constants to fold and + * process particular chunks of the input data stream in parallel. + * + * For the CRC-32 variants, the constants are precomputed according to + * these definitions: + * + * R1 = [(x4*128+32 mod P'(x) << 32)]' << 1 + * R2 = [(x4*128-32 mod P'(x) << 32)]' << 1 + * R3 = [(x128+32 mod P'(x) << 32)]' << 1 + * R4 = [(x128-32 mod P'(x) << 32)]' << 1 + * R5 = [(x64 mod P'(x) << 32)]' << 1 + * R6 = [(x32 mod P'(x) << 32)]' << 1 + * + * The bitreflected Barret reduction constant, u', is defined as + * the bit reversal of floor(x**64 / P(x)). + * + * where P(x) is the polynomial in the normal domain and the P'(x) is the + * polynomial in the reversed (bitreflected) domain. + * + * CRC-32 (IEEE 802.3 Ethernet, ...) polynomials: + * + * P(x) = 0x04C11DB7 + * P'(x) = 0xEDB88320 + * + * CRC-32C (Castagnoli) polynomials: + * + * P(x) = 0x1EDC6F41 + * P'(x) = 0x82F63B78 + */ + +static unsigned long constants_CRC_32_LE[] = { + 0x0f0e0d0c0b0a0908, 0x0706050403020100, /* BE->LE mask */ + 0x1c6e41596, 0x154442bd4, /* R2, R1 */ + 0x0ccaa009e, 0x1751997d0, /* R4, R3 */ + 0x0, 0x163cd6124, /* R5 */ + 0x0, 0x1f7011641, /* u' */ + 0x0, 0x1db710641 /* P'(x) << 1 */ +}; + +static unsigned long constants_CRC_32C_LE[] = { + 0x0f0e0d0c0b0a0908, 0x0706050403020100, /* BE->LE mask */ + 0x09e4addf8, 0x740eef02, /* R2, R1 */ + 0x14cd00bd6, 0xf20c0dfe, /* R4, R3 */ + 0x0, 0x0dd45aab8, /* R5 */ + 0x0, 0x0dea713f1, /* u' */ + 0x0, 0x105ec76f0 /* P'(x) << 1 */ +}; + +/** + * crc32_le_vgfm_generic - Compute CRC-32 (LE variant) with vector registers + * @crc: Initial CRC value, typically ~0. + * @buf: Input buffer pointer, performance might be improved if the + * buffer is on a doubleword boundary. + * @size: Size of the buffer, must be 64 bytes or greater. + * @constants: CRC-32 constant pool base pointer. + * + * Register usage: + * V0: Initial CRC value and intermediate constants and results. + * V1..V4: Data for CRC computation. + * V5..V8: Next data chunks that are fetched from the input buffer. + * V9: Constant for BE->LE conversion and shift operations + * V10..V14: CRC-32 constants. + */ +static u32 crc32_le_vgfm_generic(u32 crc, unsigned char const *buf, size_t size, unsigned long *constants) +{ + /* Load CRC-32 constants */ + fpu_vlm(CONST_PERM_LE2BE, CONST_CRC_POLY, constants); + + /* + * Load the initial CRC value. + * + * The CRC value is loaded into the rightmost word of the + * vector register and is later XORed with the LSB portion + * of the loaded input data. + */ + fpu_vzero(0); /* Clear V0 */ + fpu_vlvgf(0, crc, 3); /* Load CRC into rightmost word */ + + /* Load a 64-byte data chunk and XOR with CRC */ + fpu_vlm(1, 4, buf); + fpu_vperm(1, 1, 1, CONST_PERM_LE2BE); + fpu_vperm(2, 2, 2, CONST_PERM_LE2BE); + fpu_vperm(3, 3, 3, CONST_PERM_LE2BE); + fpu_vperm(4, 4, 4, CONST_PERM_LE2BE); + + fpu_vx(1, 0, 1); /* V1 ^= CRC */ + buf += 64; + size -= 64; + + while (size >= 64) { + fpu_vlm(5, 8, buf); + fpu_vperm(5, 5, 5, CONST_PERM_LE2BE); + fpu_vperm(6, 6, 6, CONST_PERM_LE2BE); + fpu_vperm(7, 7, 7, CONST_PERM_LE2BE); + fpu_vperm(8, 8, 8, CONST_PERM_LE2BE); + /* + * Perform a GF(2) multiplication of the doublewords in V1 with + * the R1 and R2 reduction constants in V0. The intermediate + * result is then folded (accumulated) with the next data chunk + * in V5 and stored in V1. Repeat this step for the register + * contents in V2, V3, and V4 respectively. + */ + fpu_vgfmag(1, CONST_R2R1, 1, 5); + fpu_vgfmag(2, CONST_R2R1, 2, 6); + fpu_vgfmag(3, CONST_R2R1, 3, 7); + fpu_vgfmag(4, CONST_R2R1, 4, 8); + buf += 64; + size -= 64; + } + + /* + * Fold V1 to V4 into a single 128-bit value in V1. Multiply V1 with R3 + * and R4 and accumulating the next 128-bit chunk until a single 128-bit + * value remains. + */ + fpu_vgfmag(1, CONST_R4R3, 1, 2); + fpu_vgfmag(1, CONST_R4R3, 1, 3); + fpu_vgfmag(1, CONST_R4R3, 1, 4); + + while (size >= 16) { + fpu_vl(2, buf); + fpu_vperm(2, 2, 2, CONST_PERM_LE2BE); + fpu_vgfmag(1, CONST_R4R3, 1, 2); + buf += 16; + size -= 16; + } + + /* + * Set up a vector register for byte shifts. The shift value must + * be loaded in bits 1-4 in byte element 7 of a vector register. + * Shift by 8 bytes: 0x40 + * Shift by 4 bytes: 0x20 + */ + fpu_vleib(9, 0x40, 7); + + /* + * Prepare V0 for the next GF(2) multiplication: shift V0 by 8 bytes + * to move R4 into the rightmost doubleword and set the leftmost + * doubleword to 0x1. + */ + fpu_vsrlb(0, CONST_R4R3, 9); + fpu_vleig(0, 1, 0); + + /* + * Compute GF(2) product of V1 and V0. The rightmost doubleword + * of V1 is multiplied with R4. The leftmost doubleword of V1 is + * multiplied by 0x1 and is then XORed with rightmost product. + * Implicitly, the intermediate leftmost product becomes padded + */ + fpu_vgfmg(1, 0, 1); + + /* + * Now do the final 32-bit fold by multiplying the rightmost word + * in V1 with R5 and XOR the result with the remaining bits in V1. + * + * To achieve this by a single VGFMAG, right shift V1 by a word + * and store the result in V2 which is then accumulated. Use the + * vector unpack instruction to load the rightmost half of the + * doubleword into the rightmost doubleword element of V1; the other + * half is loaded in the leftmost doubleword. + * The vector register with CONST_R5 contains the R5 constant in the + * rightmost doubleword and the leftmost doubleword is zero to ignore + * the leftmost product of V1. + */ + fpu_vleib(9, 0x20, 7); /* Shift by words */ + fpu_vsrlb(2, 1, 9); /* Store remaining bits in V2 */ + fpu_vupllf(1, 1); /* Split rightmost doubleword */ + fpu_vgfmag(1, CONST_R5, 1, 2); /* V1 = (V1 * R5) XOR V2 */ + + /* + * Apply a Barret reduction to compute the final 32-bit CRC value. + * + * The input values to the Barret reduction are the degree-63 polynomial + * in V1 (R(x)), degree-32 generator polynomial, and the reduction + * constant u. The Barret reduction result is the CRC value of R(x) mod + * P(x). + * + * The Barret reduction algorithm is defined as: + * + * 1. T1(x) = floor( R(x) / x^32 ) GF2MUL u + * 2. T2(x) = floor( T1(x) / x^32 ) GF2MUL P(x) + * 3. C(x) = R(x) XOR T2(x) mod x^32 + * + * Note: The leftmost doubleword of vector register containing + * CONST_RU_POLY is zero and, thus, the intermediate GF(2) product + * is zero and does not contribute to the final result. + */ + + /* T1(x) = floor( R(x) / x^32 ) GF2MUL u */ + fpu_vupllf(2, 1); + fpu_vgfmg(2, CONST_RU_POLY, 2); + + /* + * Compute the GF(2) product of the CRC polynomial with T1(x) in + * V2 and XOR the intermediate result, T2(x), with the value in V1. + * The final result is stored in word element 2 of V2. + */ + fpu_vupllf(2, 2); + fpu_vgfmag(2, CONST_CRC_POLY, 2, 1); + + return fpu_vlgvf(2, 2); +} + +u32 crc32_le_vgfm_16(u32 crc, unsigned char const *buf, size_t size) +{ + return crc32_le_vgfm_generic(crc, buf, size, &constants_CRC_32_LE[0]); +} + +u32 crc32c_le_vgfm_16(u32 crc, unsigned char const *buf, size_t size) +{ + return crc32_le_vgfm_generic(crc, buf, size, &constants_CRC_32C_LE[0]); +} |