arch/x86_64/lib/usercopy.c

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