1 // SPDX-License-Identifier: GPL-2.0
3 * This provides an optimized implementation of memcpy, and a simplified
4 * implementation of memset and memmove. These are used here because the
5 * standard kernel runtime versions are not yet available and we don't
6 * trust the gcc built-in implementations as they may do unexpected things
7 * (e.g. FPU ops) in the minimal decompression stub execution environment.
11 #include "../string.c"
14 static void *____memcpy(void *dest, const void *src, size_t n)
21 : "=&c" (d0), "=&D" (d1), "=&S" (d2)
22 : "0" (n >> 2), "g" (n & 3), "1" (dest), "2" (src)
28 static void *____memcpy(void *dest, const void *src, size_t n)
35 : "=&c" (d0), "=&D" (d1), "=&S" (d2)
36 : "0" (n >> 3), "g" (n & 7), "1" (dest), "2" (src)
43 void *memset(void *s, int c, size_t n)
48 for (i = 0; i < n; i++)
53 void *memmove(void *dest, const void *src, size_t n)
55 unsigned char *d = dest;
56 const unsigned char *s = src;
58 if (d <= s || d - s >= n)
59 return ____memcpy(dest, src, n);
67 /* Detect and warn about potential overlaps, but handle them with memmove. */
68 void *memcpy(void *dest, const void *src, size_t n)
70 if (dest > src && dest - src < n) {
71 warn("Avoiding potentially unsafe overlapping memcpy()!");
72 return memmove(dest, src, n);
74 return ____memcpy(dest, src, n);
78 extern void *__memset(void *s, int c, size_t n) __alias(memset);
79 extern void *__memmove(void *dest, const void *src, size_t n) __alias(memmove);
80 extern void *__memcpy(void *dest, const void *src, size_t n) __alias(memcpy);