arch/i386/lib/usercopy.c

   1 /*
   2  * User address space access functions.
   3  * The non inlined parts of asm-i386/uaccess.h are here.
   4  *
   5  * Copyright 1997 Andi Kleen <ak@muc.de>
   6  * Copyright 1997 Linus Torvalds
   7  */
   8 #include <asm/uaccess.h>
   9
  10 unsigned long
  11 __generic_copy_to_user(void *to, const void *from, unsigned long n)
  12 {
  13         if (access_ok(VERIFY_WRITE, to, n))
  14                 __copy_user(to,from,n);
  15         return n;
  16 }
  17
  18 unsigned long
  19 __generic_copy_from_user(void *to, const void *from, unsigned long n)
  20 {
  21         if (access_ok(VERIFY_READ, from, n))
  22                 __copy_user_zeroing(to,from,n);
  23         return n;
  24 }
  25
  26
  27 /*
  28  * Copy a null terminated string from userspace.
  29  */
  30
  31 #define __do_strncpy_from_user(dst,src,count,res)                          \
  32         __asm__ __volatile__(                                              \
  33                 "       testl %1,%1\n"                                     \
  34                 "       jz 2f\n"                                           \
  35                 "0:     lodsb\n"                                           \
  36                 "       stosb\n"                                           \
  37                 "       testb %%al,%%al\n"                                 \
  38                 "       jz 1f\n"                                           \
  39                 "       decl %1\n"                                         \
  40                 "       jnz 0b\n"                                          \
  41                 "1:     subl %1,%0\n"                                      \
  42                 "2:\n"                                                     \
  43                 ".section .fixup,\"ax\"\n"                                 \
  44                 "3:     movl %2,%0\n"                                      \
  45                 "       jmp 2b\n"                                          \
  46                 ".previous\n"                                              \
  47                 ".section __ex_table,\"a\"\n"                              \
  48                 "       .align 4\n"                                        \
  49                 "       .long 0b,3b\n"                                     \
  50                 ".previous"                                                \
  51                 : "=d"(res), "=c"(count)                                   \
  52                 : "i"(-EFAULT), "0"(count), "1"(count), "S"(src), "D"(dst) \
  53                 : "si", "di", "ax", "memory")
  54
  55 long
  56 __strncpy_from_user(char *dst, const char *src, long count)
  57 {
  58         long res;
  59         __do_strncpy_from_user(dst, src, count, res);
  60         return res;
  61 }
  62
  63 long
  64 strncpy_from_user(char *dst, const char *src, long count)
  65 {
  66         long res = -EFAULT;
  67         if (access_ok(VERIFY_READ, src, 1))
  68                 __do_strncpy_from_user(dst, src, count, res);
  69         return res;
  70 }
  71
  72
  73 /*
  74  * Zero Userspace
  75  */
  76
  77 #define __do_clear_user(addr,size)                                              \
  78         __asm__ __volatile__(                                           \
  79                 "0:     rep; stosl\n"                                   \
  80                 "       movl %1,%0\n"                                   \
  81                 "1:     rep; stosb\n"                                   \
  82                 "2:\n"                                                  \
  83                 ".section .fixup,\"ax\"\n"                              \
  84                 "3:     lea 0(%1,%0,4),%0\n"                            \
  85                 "       jmp 2b\n"                                       \
  86                 ".previous\n"                                           \
  87                 ".section __ex_table,\"a\"\n"                           \
  88                 "       .align 4\n"                                     \
  89                 "       .long 0b,3b\n"                                  \
  90                 "       .long 1b,2b\n"                                  \
  91                 ".previous"                                             \
  92                 : "=&c"(size)                                           \
  93                 : "r"(size & 3), "0"(size / 4), "D"(addr), "a"(0)       \
  94                 : "di")
  95
  96 unsigned long
  97 clear_user(void *to, unsigned long n)
  98 {
  99         if (access_ok(VERIFY_WRITE, to, n))
 100                 __do_clear_user(to, n);
 101         return n;
 102 }
 103
 104 unsigned long
 105 __clear_user(void *to, unsigned long n)
 106 {
 107         __do_clear_user(to, n);
 108         return n;
 109 }
 110
 111 /*
 112  * Return the size of a string (including the ending 0)
 113  *
 114  * Return 0 for error
 115  */
 116
 117 long strlen_user(const char *s)
 118 {
 119         unsigned long res;
 120
 121         __asm__ __volatile__(
 122                 "0:     repne; scasb\n"
 123                 "       notl %0\n"
 124                 "1:\n"
 125                 ".section .fixup,\"ax\"\n"
 126                 "2:     xorl %0,%0\n"
 127                 "       jmp 1b\n"
 128                 ".previous\n"
 129                 ".section __ex_table,\"a\"\n"
 130                 "       .align 4\n"
 131                 "       .long 0b,2b\n"
 132                 ".previous"
 133                 :"=c" (res), "=D" (s)
 134                 :"1" (s), "a" (0), "0" (-__addr_ok(s)));
 135         return res & -__addr_ok(s);
 136 }