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1 | // SPDX-License-Identifier: GPL-2.0-or-later |
2 | /* | |
3 | * Crypto library utility functions | |
4 | * | |
5 | * Copyright (c) 2006 Herbert Xu <herbert@gondor.apana.org.au> | |
6 | */ | |
7 | ||
8 | #include <asm/unaligned.h> | |
c616fb0c | 9 | #include <crypto/utils.h> |
6e78ad0b EB |
10 | #include <linux/module.h> |
11 | ||
12 | /* | |
13 | * XOR @len bytes from @src1 and @src2 together, writing the result to @dst | |
14 | * (which may alias one of the sources). Don't call this directly; call | |
15 | * crypto_xor() or crypto_xor_cpy() instead. | |
16 | */ | |
17 | void __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 as | |
31 | * needed to advance dst and src to values whose alignments | |
32 | * equal their relative alignment. This will allow us to | |
33 | * 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 | } | |
86 | EXPORT_SYMBOL_GPL(__crypto_xor); | |
87 | ||
88 | MODULE_LICENSE("GPL"); |