1 /* 2 * User address space access functions. 3 * 4 * Copyright 1997 Andi Kleen <ak@muc.de> 5 * Copyright 1997 Linus Torvalds 6 * Copyright 2002 Andi Kleen <ak@suse.de> 7 */ 8 #include <linux/module.h> 9 #include <asm/uaccess.h> 10 11 /* 12 * Copy a null terminated string from userspace. 13 */ 14 15 #define __do_strncpy_from_user(dst,src,count,res) \ 16 do { \ 17 long __d0, __d1, __d2; \ 18 might_sleep(); \ 19 __asm__ __volatile__( \ 20 " testq %1,%1\n" \ 21 " jz 2f\n" \ 22 "0: lodsb\n" \ 23 " stosb\n" \ 24 " testb %%al,%%al\n" \ 25 " jz 1f\n" \ 26 " decq %1\n" \ 27 " jnz 0b\n" \ 28 "1: subq %1,%0\n" \ 29 "2:\n" \ 30 ".section .fixup,\"ax\"\n" \ 31 "3: movq %5,%0\n" \ 32 " jmp 2b\n" \ 33 ".previous\n" \ 34 ".section __ex_table,\"a\"\n" \ 35 " .align 8\n" \ 36 " .quad 0b,3b\n" \ 37 ".previous" \ 38 : "=r"(res), "=c"(count), "=&a" (__d0), "=&S" (__d1), \ 39 "=&D" (__d2) \ 40 : "i"(-EFAULT), "0"(count), "1"(count), "3"(src), "4"(dst) \ 41 : "memory"); \ 42 } while (0) 43 44 long 45 __strncpy_from_user(char *dst, const char __user *src, long count) 46 { 47 long res; 48 __do_strncpy_from_user(dst, src, count, res); 49 return res; 50 } 51 EXPORT_SYMBOL(__strncpy_from_user); 52 53 long 54 strncpy_from_user(char *dst, const char __user *src, long count) 55 { 56 long res = -EFAULT; 57 if (access_ok(VERIFY_READ, src, 1)) 58 return __strncpy_from_user(dst, src, count); 59 return res; 60 } 61 EXPORT_SYMBOL(strncpy_from_user); 62 63 /* 64 * Zero Userspace 65 */ 66 67 unsigned long __clear_user(void __user *addr, unsigned long size) 68 { 69 long __d0; 70 might_sleep(); 71 /* no memory constraint because it doesn't change any memory gcc knows 72 about */ 73 asm volatile( 74 " testq %[size8],%[size8]\n" 75 " jz 4f\n" 76 "0: movq %[zero],(%[dst])\n" 77 " addq %[eight],%[dst]\n" 78 " decl %%ecx ; jnz 0b\n" 79 "4: movq %[size1],%%rcx\n" 80 " testl %%ecx,%%ecx\n" 81 " jz 2f\n" 82 "1: movb %b[zero],(%[dst])\n" 83 " incq %[dst]\n" 84 " decl %%ecx ; jnz 1b\n" 85 "2:\n" 86 ".section .fixup,\"ax\"\n" 87 "3: lea 0(%[size1],%[size8],8),%[size8]\n" 88 " jmp 2b\n" 89 ".previous\n" 90 ".section __ex_table,\"a\"\n" 91 " .align 8\n" 92 " .quad 0b,3b\n" 93 " .quad 1b,2b\n" 94 ".previous" 95 : [size8] "=c"(size), [dst] "=&D" (__d0) 96 : [size1] "r"(size & 7), "[size8]" (size / 8), "[dst]"(addr), 97 [zero] "r" (0UL), [eight] "r" (8UL)); 98 return size; 99 } 100 EXPORT_SYMBOL(__clear_user); 101 102 unsigned long clear_user(void __user *to, unsigned long n) 103 { 104 if (access_ok(VERIFY_WRITE, to, n)) 105 return __clear_user(to, n); 106 return n; 107 } 108 EXPORT_SYMBOL(clear_user); 109 110 /* 111 * Return the size of a string (including the ending 0) 112 * 113 * Return 0 on exception, a value greater than N if too long 114 */ 115 116 long __strnlen_user(const char __user *s, long n) 117 { 118 long res = 0; 119 char c; 120 121 while (1) { 122 if (res>n) 123 return n+1; 124 if (__get_user(c, s)) 125 return 0; 126 if (!c) 127 return res+1; 128 res++; 129 s++; 130 } 131 } 132 EXPORT_SYMBOL(__strnlen_user); 133 134 long strnlen_user(const char __user *s, long n) 135 { 136 if (!access_ok(VERIFY_READ, s, n)) 137 return 0; 138 return __strnlen_user(s, n); 139 } 140 EXPORT_SYMBOL(strnlen_user); 141 142 long strlen_user(const char __user *s) 143 { 144 long res = 0; 145 char c; 146 147 for (;;) { 148 if (get_user(c, s)) 149 return 0; 150 if (!c) 151 return res+1; 152 res++; 153 s++; 154 } 155 } 156 EXPORT_SYMBOL(strlen_user); 157 158 unsigned long copy_in_user(void __user *to, const void __user *from, unsigned len) 159 { 160 if (access_ok(VERIFY_WRITE, to, len) && access_ok(VERIFY_READ, from, len)) { 161 return copy_user_generic((__force void *)to, (__force void *)from, len); 162 } 163 return len; 164 } 165 EXPORT_SYMBOL(copy_in_user); 166 167