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