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Diffstat (limited to 'arch/s390/crypto/crc32be-vx.S')
| -rw-r--r-- | arch/s390/crypto/crc32be-vx.S | 207 |
1 files changed, 207 insertions, 0 deletions
diff --git a/arch/s390/crypto/crc32be-vx.S b/arch/s390/crypto/crc32be-vx.S new file mode 100644 index 000000000000..8013989cd2e5 --- /dev/null +++ b/arch/s390/crypto/crc32be-vx.S @@ -0,0 +1,207 @@ +/* + * Hardware-accelerated CRC-32 variants for Linux on z Systems + * + * Use the z/Architecture Vector Extension Facility to accelerate the + * computing of CRC-32 checksums. + * + * This CRC-32 implementation algorithm processes the most-significant + * bit first (BE). + * + * Copyright IBM Corp. 2015 + * Author(s): Hendrik Brueckner <brueckner@linux.vnet.ibm.com> + */ + +#include <linux/linkage.h> +#include <asm/vx-insn.h> + +/* Vector register range containing CRC-32 constants */ +#define CONST_R1R2 %v9 +#define CONST_R3R4 %v10 +#define CONST_R5 %v11 +#define CONST_R6 %v12 +#define CONST_RU_POLY %v13 +#define CONST_CRC_POLY %v14 + +.data +.align 8 + +/* + * 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 defintions: + * + * R1 = x4*128+64 mod P(x) + * R2 = x4*128 mod P(x) + * R3 = x128+64 mod P(x) + * R4 = x128 mod P(x) + * R5 = x96 mod P(x) + * R6 = x64 mod P(x) + * + * Barret reduction constant, u, is defined as 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. + * + * Note that the constant definitions below are extended in order to compute + * intermediate results with a single VECTOR GALOIS FIELD MULTIPLY instruction. + * The righmost doubleword can be 0 to prevent contribution to the result or + * can be multiplied by 1 to perform an XOR without the need for a separate + * VECTOR EXCLUSIVE OR instruction. + * + * CRC-32 (IEEE 802.3 Ethernet, ...) polynomials: + * + * P(x) = 0x04C11DB7 + * P'(x) = 0xEDB88320 + */ + +.Lconstants_CRC_32_BE: + .quad 0x08833794c, 0x0e6228b11 # R1, R2 + .quad 0x0c5b9cd4c, 0x0e8a45605 # R3, R4 + .quad 0x0f200aa66, 1 << 32 # R5, x32 + .quad 0x0490d678d, 1 # R6, 1 + .quad 0x104d101df, 0 # u + .quad 0x104C11DB7, 0 # P(x) + +.previous + +.text +/* + * The CRC-32 function(s) use these calling conventions: + * + * Parameters: + * + * %r2: Initial CRC value, typically ~0; and final CRC (return) value. + * %r3: Input buffer pointer, performance might be improved if the + * buffer is on a doubleword boundary. + * %r4: Length of the buffer, must be 64 bytes or greater. + * + * Register usage: + * + * %r5: CRC-32 constant pool base pointer. + * 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..V14: CRC-32 constants. + */ +ENTRY(crc32_be_vgfm_16) + /* Load CRC-32 constants */ + larl %r5,.Lconstants_CRC_32_BE + VLM CONST_R1R2,CONST_CRC_POLY,0,%r5 + + /* Load the initial CRC value into the leftmost word of V0. */ + VZERO %v0 + VLVGF %v0,%r2,0 + + /* Load a 64-byte data chunk and XOR with CRC */ + VLM %v1,%v4,0,%r3 /* 64-bytes into V1..V4 */ + VX %v1,%v0,%v1 /* V1 ^= CRC */ + aghi %r3,64 /* BUF = BUF + 64 */ + aghi %r4,-64 /* LEN = LEN - 64 */ + + /* Check remaining buffer size and jump to proper folding method */ + cghi %r4,64 + jl .Lless_than_64bytes + +.Lfold_64bytes_loop: + /* Load the next 64-byte data chunk into V5 to V8 */ + VLM %v5,%v8,0,%r3 + + /* + * Perform a GF(2) multiplication of the doublewords in V1 with + * the 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. + */ + VGFMAG %v1,CONST_R1R2,%v1,%v5 + VGFMAG %v2,CONST_R1R2,%v2,%v6 + VGFMAG %v3,CONST_R1R2,%v3,%v7 + VGFMAG %v4,CONST_R1R2,%v4,%v8 + + /* Adjust buffer pointer and length for next loop */ + aghi %r3,64 /* BUF = BUF + 64 */ + aghi %r4,-64 /* LEN = LEN - 64 */ + + cghi %r4,64 + jnl .Lfold_64bytes_loop + +.Lless_than_64bytes: + /* Fold V1 to V4 into a single 128-bit value in V1 */ + VGFMAG %v1,CONST_R3R4,%v1,%v2 + VGFMAG %v1,CONST_R3R4,%v1,%v3 + VGFMAG %v1,CONST_R3R4,%v1,%v4 + + /* Check whether to continue with 64-bit folding */ + cghi %r4,16 + jl .Lfinal_fold + +.Lfold_16bytes_loop: + + VL %v2,0,,%r3 /* Load next data chunk */ + VGFMAG %v1,CONST_R3R4,%v1,%v2 /* Fold next data chunk */ + + /* Adjust buffer pointer and size for folding next data chunk */ + aghi %r3,16 + aghi %r4,-16 + + /* Process remaining data chunks */ + cghi %r4,16 + jnl .Lfold_16bytes_loop + +.Lfinal_fold: + /* + * The R5 constant is used to fold a 128-bit value into an 96-bit value + * that is XORed with the next 96-bit input data chunk. To use a single + * VGFMG instruction, multiply the rightmost 64-bit with x^32 (1<<32) to + * form an intermediate 96-bit value (with appended zeros) which is then + * XORed with the intermediate reduction result. + */ + VGFMG %v1,CONST_R5,%v1 + + /* + * Further reduce the remaining 96-bit value to a 64-bit value using a + * single VGFMG, the rightmost doubleword is multiplied with 0x1. The + * intermediate result is then XORed with the product of the leftmost + * doubleword with R6. The result is a 64-bit value and is subject to + * the Barret reduction. + */ + VGFMG %v1,CONST_R6,%v1 + + /* + * 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: To compensate the division by x^32, use the vector unpack + * instruction to move the leftmost word into the leftmost doubleword + * of the vector register. The rightmost doubleword is multiplied + * with zero to not contribute to the intermedate results. + */ + + /* T1(x) = floor( R(x) / x^32 ) GF2MUL u */ + VUPLLF %v2,%v1 + VGFMG %v2,CONST_RU_POLY,%v2 + + /* + * Compute the GF(2) product of the CRC polynomial in VO with T1(x) in + * V2 and XOR the intermediate result, T2(x), with the value in V1. + * The final result is in the rightmost word of V2. + */ + VUPLLF %v2,%v2 + VGFMAG %v2,CONST_CRC_POLY,%v2,%v1 + +.Ldone: + VLGVF %r2,%v2,3 + br %r14 + +.previous |