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