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1// SPDX-License-Identifier: GPL-2.0-or-later2/*3 * Crypto library utility functions4 *5 * Copyright (c) 2006 Herbert Xu <herbert@gondor.apana.org.au>6 */7 8#include <linux/unaligned.h>9#include <crypto/utils.h>10#include <linux/module.h>11 12/*13 * XOR @len bytes from @src1 and @src2 together, writing the result to @dst14 * (which may alias one of the sources). Don't call this directly; call15 * crypto_xor() or crypto_xor_cpy() instead.16 */17void __crypto_xor(u8 *dst, const u8 *src1, const u8 *src2, unsigned int len)18{19 int relalign = 0;20 21 if (!IS_ENABLED(CONFIG_HAVE_EFFICIENT_UNALIGNED_ACCESS)) {22 int size = sizeof(unsigned long);23 int d = (((unsigned long)dst ^ (unsigned long)src1) |24 ((unsigned long)dst ^ (unsigned long)src2)) &25 (size - 1);26 27 relalign = d ? 1 << __ffs(d) : size;28 29 /*30 * If we care about alignment, process as many bytes as31 * needed to advance dst and src to values whose alignments32 * equal their relative alignment. This will allow us to33 * process the remainder of the input using optimal strides.34 */35 while (((unsigned long)dst & (relalign - 1)) && len > 0) {36 *dst++ = *src1++ ^ *src2++;37 len--;38 }39 }40 41 while (IS_ENABLED(CONFIG_64BIT) && len >= 8 && !(relalign & 7)) {42 if (IS_ENABLED(CONFIG_HAVE_EFFICIENT_UNALIGNED_ACCESS)) {43 u64 l = get_unaligned((u64 *)src1) ^44 get_unaligned((u64 *)src2);45 put_unaligned(l, (u64 *)dst);46 } else {47 *(u64 *)dst = *(u64 *)src1 ^ *(u64 *)src2;48 }49 dst += 8;50 src1 += 8;51 src2 += 8;52 len -= 8;53 }54 55 while (len >= 4 && !(relalign & 3)) {56 if (IS_ENABLED(CONFIG_HAVE_EFFICIENT_UNALIGNED_ACCESS)) {57 u32 l = get_unaligned((u32 *)src1) ^58 get_unaligned((u32 *)src2);59 put_unaligned(l, (u32 *)dst);60 } else {61 *(u32 *)dst = *(u32 *)src1 ^ *(u32 *)src2;62 }63 dst += 4;64 src1 += 4;65 src2 += 4;66 len -= 4;67 }68 69 while (len >= 2 && !(relalign & 1)) {70 if (IS_ENABLED(CONFIG_HAVE_EFFICIENT_UNALIGNED_ACCESS)) {71 u16 l = get_unaligned((u16 *)src1) ^72 get_unaligned((u16 *)src2);73 put_unaligned(l, (u16 *)dst);74 } else {75 *(u16 *)dst = *(u16 *)src1 ^ *(u16 *)src2;76 }77 dst += 2;78 src1 += 2;79 src2 += 2;80 len -= 2;81 }82 83 while (len--)84 *dst++ = *src1++ ^ *src2++;85}86EXPORT_SYMBOL_GPL(__crypto_xor);87 88MODULE_DESCRIPTION("Crypto library utility functions");89MODULE_LICENSE("GPL");90