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81 lines
1.9 KiB
81 lines
1.9 KiB
// SPDX-License-Identifier: GPL-2.0 |
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/* |
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* This provides an optimized implementation of memcpy, and a simplified |
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* implementation of memset and memmove. These are used here because the |
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* standard kernel runtime versions are not yet available and we don't |
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* trust the gcc built-in implementations as they may do unexpected things |
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* (e.g. FPU ops) in the minimal decompression stub execution environment. |
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*/ |
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#include "error.h" |
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#include "../string.c" |
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#ifdef CONFIG_X86_32 |
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static void *____memcpy(void *dest, const void *src, size_t n) |
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{ |
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int d0, d1, d2; |
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asm volatile( |
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"rep ; movsl\n\t" |
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"movl %4,%%ecx\n\t" |
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"rep ; movsb\n\t" |
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: "=&c" (d0), "=&D" (d1), "=&S" (d2) |
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: "0" (n >> 2), "g" (n & 3), "1" (dest), "2" (src) |
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: "memory"); |
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return dest; |
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} |
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#else |
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static void *____memcpy(void *dest, const void *src, size_t n) |
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{ |
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long d0, d1, d2; |
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asm volatile( |
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"rep ; movsq\n\t" |
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"movq %4,%%rcx\n\t" |
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"rep ; movsb\n\t" |
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: "=&c" (d0), "=&D" (d1), "=&S" (d2) |
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: "0" (n >> 3), "g" (n & 7), "1" (dest), "2" (src) |
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: "memory"); |
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return dest; |
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} |
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#endif |
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void *memset(void *s, int c, size_t n) |
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{ |
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int i; |
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char *ss = s; |
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for (i = 0; i < n; i++) |
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ss[i] = c; |
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return s; |
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} |
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void *memmove(void *dest, const void *src, size_t n) |
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{ |
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unsigned char *d = dest; |
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const unsigned char *s = src; |
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if (d <= s || d - s >= n) |
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return ____memcpy(dest, src, n); |
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while (n-- > 0) |
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d[n] = s[n]; |
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return dest; |
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} |
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/* Detect and warn about potential overlaps, but handle them with memmove. */ |
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void *memcpy(void *dest, const void *src, size_t n) |
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{ |
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if (dest > src && dest - src < n) { |
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warn("Avoiding potentially unsafe overlapping memcpy()!"); |
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return memmove(dest, src, n); |
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} |
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return ____memcpy(dest, src, n); |
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} |
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#ifdef CONFIG_KASAN |
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extern void *__memset(void *s, int c, size_t n) __alias(memset); |
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extern void *__memmove(void *dest, const void *src, size_t n) __alias(memmove); |
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extern void *__memcpy(void *dest, const void *src, size_t n) __alias(memcpy); |
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#endif
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