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88 lines
2.2 KiB
88 lines
2.2 KiB
// SPDX-License-Identifier: GPL-2.0-or-later |
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/* |
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* Crypto library utility functions |
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* |
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* Copyright (c) 2006 Herbert Xu <[email protected]> |
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*/ |
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#include <asm/unaligned.h> |
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#include <crypto/algapi.h> |
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#include <linux/module.h> |
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/* |
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* XOR @len bytes from @src1 and @src2 together, writing the result to @dst |
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* (which may alias one of the sources). Don't call this directly; call |
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* crypto_xor() or crypto_xor_cpy() instead. |
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*/ |
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void __crypto_xor(u8 *dst, const u8 *src1, const u8 *src2, unsigned int len) |
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{ |
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int relalign = 0; |
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if (!IS_ENABLED(CONFIG_HAVE_EFFICIENT_UNALIGNED_ACCESS)) { |
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int size = sizeof(unsigned long); |
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int d = (((unsigned long)dst ^ (unsigned long)src1) | |
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((unsigned long)dst ^ (unsigned long)src2)) & |
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(size - 1); |
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relalign = d ? 1 << __ffs(d) : size; |
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/* |
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* If we care about alignment, process as many bytes as |
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* needed to advance dst and src to values whose alignments |
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* equal their relative alignment. This will allow us to |
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* process the remainder of the input using optimal strides. |
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*/ |
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while (((unsigned long)dst & (relalign - 1)) && len > 0) { |
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*dst++ = *src1++ ^ *src2++; |
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len--; |
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} |
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} |
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while (IS_ENABLED(CONFIG_64BIT) && len >= 8 && !(relalign & 7)) { |
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if (IS_ENABLED(CONFIG_HAVE_EFFICIENT_UNALIGNED_ACCESS)) { |
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u64 l = get_unaligned((u64 *)src1) ^ |
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get_unaligned((u64 *)src2); |
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put_unaligned(l, (u64 *)dst); |
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} else { |
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*(u64 *)dst = *(u64 *)src1 ^ *(u64 *)src2; |
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} |
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dst += 8; |
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src1 += 8; |
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src2 += 8; |
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len -= 8; |
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} |
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while (len >= 4 && !(relalign & 3)) { |
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if (IS_ENABLED(CONFIG_HAVE_EFFICIENT_UNALIGNED_ACCESS)) { |
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u32 l = get_unaligned((u32 *)src1) ^ |
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get_unaligned((u32 *)src2); |
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put_unaligned(l, (u32 *)dst); |
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} else { |
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*(u32 *)dst = *(u32 *)src1 ^ *(u32 *)src2; |
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} |
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dst += 4; |
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src1 += 4; |
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src2 += 4; |
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len -= 4; |
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} |
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while (len >= 2 && !(relalign & 1)) { |
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if (IS_ENABLED(CONFIG_HAVE_EFFICIENT_UNALIGNED_ACCESS)) { |
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u16 l = get_unaligned((u16 *)src1) ^ |
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get_unaligned((u16 *)src2); |
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put_unaligned(l, (u16 *)dst); |
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} else { |
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*(u16 *)dst = *(u16 *)src1 ^ *(u16 *)src2; |
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} |
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dst += 2; |
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src1 += 2; |
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src2 += 2; |
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len -= 2; |
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} |
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while (len--) |
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*dst++ = *src1++ ^ *src2++; |
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} |
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EXPORT_SYMBOL_GPL(__crypto_xor); |
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MODULE_LICENSE("GPL");
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