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2fffee536c
The arm64 implementation of the CRC-T10DIF algorithm uses the 64x64 bit polynomial multiplication instructions, which are optional in the architecture, and if these instructions are not available, we fall back to the C routine which is slow and inefficient. So let's reuse the 64x64 bit PMULL alternative from the GHASH driver that uses a sequence of ~40 instructions involving 8x8 bit PMULL and some shifting and masking. This is a lot slower than the original, but it is still twice as fast as the current [unoptimized] C code on Cortex-A53, and it is time invariant and much easier on the D-cache. Signed-off-by: Ard Biesheuvel <ard.biesheuvel@linaro.org> Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>
111 lines
2.6 KiB
C
111 lines
2.6 KiB
C
/*
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* Accelerated CRC-T10DIF using arm64 NEON and Crypto Extensions instructions
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*
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* Copyright (C) 2016 - 2017 Linaro Ltd <ard.biesheuvel@linaro.org>
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*
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* This program is free software; you can redistribute it and/or modify
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* it under the terms of the GNU General Public License version 2 as
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* published by the Free Software Foundation.
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*/
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#include <linux/cpufeature.h>
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#include <linux/crc-t10dif.h>
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#include <linux/init.h>
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#include <linux/kernel.h>
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#include <linux/module.h>
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#include <linux/string.h>
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#include <crypto/internal/hash.h>
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#include <asm/neon.h>
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#include <asm/simd.h>
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#define CRC_T10DIF_PMULL_CHUNK_SIZE 16U
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asmlinkage u16 crc_t10dif_pmull_p64(u16 init_crc, const u8 buf[], u64 len);
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asmlinkage u16 crc_t10dif_pmull_p8(u16 init_crc, const u8 buf[], u64 len);
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static u16 (*crc_t10dif_pmull)(u16 init_crc, const u8 buf[], u64 len);
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static int crct10dif_init(struct shash_desc *desc)
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{
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u16 *crc = shash_desc_ctx(desc);
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*crc = 0;
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return 0;
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}
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static int crct10dif_update(struct shash_desc *desc, const u8 *data,
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unsigned int length)
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{
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u16 *crc = shash_desc_ctx(desc);
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unsigned int l;
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if (unlikely((u64)data % CRC_T10DIF_PMULL_CHUNK_SIZE)) {
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l = min_t(u32, length, CRC_T10DIF_PMULL_CHUNK_SIZE -
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((u64)data % CRC_T10DIF_PMULL_CHUNK_SIZE));
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*crc = crc_t10dif_generic(*crc, data, l);
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length -= l;
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data += l;
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}
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if (length > 0) {
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if (may_use_simd()) {
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kernel_neon_begin();
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*crc = crc_t10dif_pmull(*crc, data, length);
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kernel_neon_end();
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} else {
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*crc = crc_t10dif_generic(*crc, data, length);
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}
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}
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return 0;
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}
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static int crct10dif_final(struct shash_desc *desc, u8 *out)
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{
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u16 *crc = shash_desc_ctx(desc);
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*(u16 *)out = *crc;
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return 0;
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}
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static struct shash_alg crc_t10dif_alg = {
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.digestsize = CRC_T10DIF_DIGEST_SIZE,
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.init = crct10dif_init,
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.update = crct10dif_update,
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.final = crct10dif_final,
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.descsize = CRC_T10DIF_DIGEST_SIZE,
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.base.cra_name = "crct10dif",
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.base.cra_driver_name = "crct10dif-arm64-ce",
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.base.cra_priority = 200,
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.base.cra_blocksize = CRC_T10DIF_BLOCK_SIZE,
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.base.cra_module = THIS_MODULE,
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};
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static int __init crc_t10dif_mod_init(void)
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{
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if (elf_hwcap & HWCAP_PMULL)
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crc_t10dif_pmull = crc_t10dif_pmull_p64;
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else
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crc_t10dif_pmull = crc_t10dif_pmull_p8;
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return crypto_register_shash(&crc_t10dif_alg);
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}
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static void __exit crc_t10dif_mod_exit(void)
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{
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crypto_unregister_shash(&crc_t10dif_alg);
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}
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module_cpu_feature_match(ASIMD, crc_t10dif_mod_init);
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module_exit(crc_t10dif_mod_exit);
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MODULE_AUTHOR("Ard Biesheuvel <ard.biesheuvel@linaro.org>");
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MODULE_LICENSE("GPL v2");
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MODULE_ALIAS_CRYPTO("crct10dif");
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MODULE_ALIAS_CRYPTO("crct10dif-arm64-ce");
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