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| 3 | * This provides an optimized implementation of memcpy, and a simplified
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| 4 | * implementation of memset and memmove. These are used here because the
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| 5 | * standard kernel runtime versions are not yet available and we don't
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| 6 | * trust the gcc built-in implementations as they may do unexpected things
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| 7 | * (e.g. FPU ops) in the minimal decompression stub execution environment.
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| 8 |
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| 9 | #include "error.h"
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| 10 |
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| 11 | #include "../string.c"
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| 12 |
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| 13 | #ifdef CONFIG_X86_32
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| 14 | static void *____memcpy(void *dest, const void *src, size_t n)
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| 15 | {
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| 16 | int d0, d1, d2;
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| 17 | asm volatile(
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| 18 | "rep movsl\n\t"
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| 19 | "movl %4,%%ecx\n\t"
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| 20 | "rep movsb"
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| 21 | : "=&c" (d0), "=&D" (d1), "=&S" (d2)
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| 22 | : "0" (n >> 2), "g" (n & 3), "1" (dest), "2" (src)
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| 23 | : "memory");
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| 24 |
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| 25 | return dest;
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| 26 | }
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| 27 | #else
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| 28 | static void *____memcpy(void *dest, const void *src, size_t n)
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| 29 | {
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| 30 | long d0, d1, d2;
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| 31 | asm volatile(
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| 32 | "rep movsq\n\t"
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| 33 | "movq %4,%%rcx\n\t"
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| 34 | "rep movsb"
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| 35 | : "=&c" (d0), "=&D" (d1), "=&S" (d2)
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| 36 | : "0" (n >> 3), "g" (n & 7), "1" (dest), "2" (src)
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| 37 | : "memory");
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| 38 |
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| 39 | return dest;
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| 40 | }
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| 41 | #endif
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| 42 |
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| 43 | void *memset(void *s, int c, size_t n)
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| 44 | {
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| 45 | int i;
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| 46 | char *ss = s;
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| 47 |
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| 48 | for (i = 0; i < n; i++)
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| 49 | ss[i] = c;
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| 50 | return s;
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| 51 | }
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| 52 |
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| 53 | void *memmove(void *dest, const void *src, size_t n)
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| 54 | {
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| 55 | unsigned char *d = dest;
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| 56 | const unsigned char *s = src;
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| 57 |
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| 58 | if (d <= s || d - s >= n)
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| 59 | return ____memcpy(dest, src, n);
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| 60 |
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| 61 | while (n-- > 0)
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| 62 | d[n] = s[n];
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| 63 |
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| 64 | return dest;
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| 65 | }
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| 66 |
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| 67 |
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| 68 | void *memcpy(void *dest, const void *src, size_t n)
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| 69 | {
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| 70 | if (dest > src && dest - src < n) {
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| 71 | warn("Avoiding potentially unsafe overlapping memcpy()!");
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| 72 | return memmove(dest, src, n);
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| 73 | }
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| 74 | return ____memcpy(dest, src, n);
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| 75 | }
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| 76 |
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| 77 | #ifdef CONFIG_KASAN
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| 78 | extern void *__memset(void *s, int c, size_t n) __alias(memset);
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| 79 | extern void *__memmove(void *dest, const void *src, size_t n) __alias(memmove);
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| 80 | extern void *__memcpy(void *dest, const void *src, size_t n) __alias(memcpy);
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| 81 | #endif
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