| 1 | |
| 2 | |
| 3 | * Crypto library utility functions
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| 4 | *
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| 5 | * Copyright (c) 2006 Herbert Xu <[email protected]>
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| 6 |
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| 7 |
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| 8 | #include <crypto/utils.h>
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| 9 | #include <linux/export.h>
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| 10 | #include <linux/module.h>
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| 11 | #include <linux/unaligned.h>
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| 12 |
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| 13 | |
| 14 | * XOR @len bytes from @src1 and @src2 together, writing the result to @dst
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| 15 | * (which may alias one of the sources). Don't call this directly; call
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| 16 | * crypto_xor() or crypto_xor_cpy() instead.
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| 17 |
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| 18 | void __crypto_xor(u8 *dst, const u8 *src1, const u8 *src2, unsigned int len)
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| 19 | {
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| 20 | int relalign = 0;
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| 21 |
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| 22 | if (!IS_ENABLED(CONFIG_HAVE_EFFICIENT_UNALIGNED_ACCESS)) {
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| 23 | int size = sizeof(unsigned long);
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| 24 | int d = (((unsigned long)dst ^ (unsigned long)src1) |
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| 25 | ((unsigned long)dst ^ (unsigned long)src2)) &
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| 26 | (size - 1);
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| 27 |
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| 28 | relalign = d ? 1 << __ffs(d) : size;
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| 29 |
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| 30 | |
| 31 | * If we care about alignment, process as many bytes as
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| 32 | * needed to advance dst and src to values whose alignments
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| 33 | * equal their relative alignment. This will allow us to
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| 34 | * process the remainder of the input using optimal strides.
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| 35 |
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| 36 | while (((unsigned long)dst & (relalign - 1)) && len > 0) {
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| 37 | *dst++ = *src1++ ^ *src2++;
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| 38 | len--;
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| 39 | }
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| 40 | }
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| 41 |
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| 42 | while (IS_ENABLED(CONFIG_64BIT) && len >= 8 && !(relalign & 7)) {
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| 43 | if (IS_ENABLED(CONFIG_HAVE_EFFICIENT_UNALIGNED_ACCESS)) {
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| 44 | u64 l = get_unaligned((u64 *)src1) ^
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| 45 | get_unaligned((u64 *)src2);
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| 46 | put_unaligned(l, (u64 *)dst);
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| 47 | } else {
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| 48 | *(u64 *)dst = *(u64 *)src1 ^ *(u64 *)src2;
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| 49 | }
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| 50 | dst += 8;
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| 51 | src1 += 8;
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| 52 | src2 += 8;
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| 53 | len -= 8;
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| 54 | }
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| 55 |
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| 56 | while (len >= 4 && !(relalign & 3)) {
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| 57 | if (IS_ENABLED(CONFIG_HAVE_EFFICIENT_UNALIGNED_ACCESS)) {
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| 58 | u32 l = get_unaligned((u32 *)src1) ^
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| 59 | get_unaligned((u32 *)src2);
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| 60 | put_unaligned(l, (u32 *)dst);
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| 61 | } else {
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| 62 | *(u32 *)dst = *(u32 *)src1 ^ *(u32 *)src2;
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| 63 | }
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| 64 | dst += 4;
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| 65 | src1 += 4;
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| 66 | src2 += 4;
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| 67 | len -= 4;
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| 68 | }
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| 69 |
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| 70 | while (len >= 2 && !(relalign & 1)) {
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| 71 | if (IS_ENABLED(CONFIG_HAVE_EFFICIENT_UNALIGNED_ACCESS)) {
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| 72 | u16 l = get_unaligned((u16 *)src1) ^
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| 73 | get_unaligned((u16 *)src2);
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| 74 | put_unaligned(l, (u16 *)dst);
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| 75 | } else {
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| 76 | *(u16 *)dst = *(u16 *)src1 ^ *(u16 *)src2;
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| 77 | }
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| 78 | dst += 2;
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| 79 | src1 += 2;
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| 80 | src2 += 2;
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| 81 | len -= 2;
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| 82 | }
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| 83 |
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| 84 | while (len--)
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| 85 | *dst++ = *src1++ ^ *src2++;
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| 86 | }
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| 87 | EXPORT_SYMBOL_GPL(__crypto_xor);
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| 88 |
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| 89 | MODULE_DESCRIPTION("Crypto library utility functions");
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| 90 | MODULE_LICENSE("GPL");
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