89 lines
2.2 KiB
C
89 lines
2.2 KiB
C
// 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 <herbert@gondor.apana.org.au>
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*/
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#include <asm/unaligned.h>
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#include <crypto/utils.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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