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 inline unsigned long
  11 __generic_copy_to_user(void *to, const void *from, unsigned long n)
  12 {
  13         if ((unsigned long) to < TASK_SIZE)
  14                 __check_locks(1);
  15         if (access_ok(VERIFY_WRITE, to, n))
  16                 __copy_user(to,from,n);
  17         return n;
  18 }
  19
  20 inline unsigned long
  21 __generic_copy_from_user(void *to, const void *from, unsigned long n)
  22 {
  23         if ((unsigned long) from < TASK_SIZE)
  24                 __check_locks(1);
  25         if (access_ok(VERIFY_READ, from, n))
  26                 __copy_user(to,from,n);
  27         return n;
  28 }
  29
  30
  31 /*
  32  * Copy a null terminated string from userspace.
  33  */
  34
  35 #define __do_strncpy_from_user(dst,src,count,res)                          \
  36         __asm__ __volatile__(                                              \
  37                 "       testl %1,%1\n"                                     \
  38                 "       jz 2f\n"                                           \
  39                 "0:     lodsb\n"                                           \
  40                 "       stosb\n"                                           \
  41                 "       testb %%al,%%al\n"                                 \
  42                 "       jz 1f\n"                                           \
  43                 "       decl %1\n"                                         \
  44                 "       jnz 0b\n"                                          \
  45                 "1:     subl %1,%0\n"                                      \
  46                 "2:\n"                                                     \
  47                 ".section .fixup,\"ax\"\n"                                 \
  48                 "3:     movl %2,%0\n"                                      \
  49                 "       jmp 2b\n"                                          \
  50                 ".previous\n"                                              \
  51                 ".section __ex_table,\"a\"\n"                              \
  52                 "       .align 4\n"                                        \
  53                 "       .long 0b,3b\n"                                     \
  54                 ".previous"                                                \
  55                 : "=d"(res), "=c"(count)                                   \
  56                 : "i"(-EFAULT), "0"(count), "1"(count), "S"(src), "D"(dst) \
  57                 : "si", "di", "ax", "memory")
  58
  59 long
  60 __strncpy_from_user(char *dst, const char *src, long count)
  61 {
  62         long res;
  63         __check_locks(1);
  64         __do_strncpy_from_user(dst, src, count, res);
  65         return res;
  66 }
  67
  68 long
  69 strncpy_from_user(char *dst, const char *src, long count)
  70 {
  71         long res = -EFAULT;
  72         __check_locks(1);
  73         if (access_ok(VERIFY_READ, src, 1))
  74                 __do_strncpy_from_user(dst, src, count, res);
  75         return res;
  76 }
  77
  78
  79 /*
  80  * Zero Userspace
  81  */
  82
  83 #define __do_clear_user(addr,size)                                              \
  84         __asm__ __volatile__(                                           \
  85                 "0:     rep; stosl\n"                                   \
  86                 "       movl %1,%0\n"                                   \
  87                 "1:     rep; stosb\n"                                   \
  88                 "2:\n"                                                  \
  89                 ".section .fixup,\"ax\"\n"                              \
  90                 "3:     lea 0(%1,%0,4),%0\n"                            \
  91                 "       jmp 2b\n"                                       \
  92                 ".previous\n"                                           \
  93                 ".section __ex_table,\"a\"\n"                           \
  94                 "       .align 4\n"                                     \
  95                 "       .long 0b,3b\n"                                  \
  96                 "       .long 1b,2b\n"                                  \
  97                 ".previous"                                             \
  98                 : "=&c"(size)                                           \
  99                 : "r"(size & 3), "0"(size / 4), "D"(addr), "a"(0)       \
 100                 : "di")
 101
 102 unsigned long
 103 clear_user(void *to, unsigned long n)
 104 {
 105         __check_locks(1);
 106         if (access_ok(VERIFY_WRITE, to, n))
 107                 __do_clear_user(to, n);
 108         return n;
 109 }
 110
 111 unsigned long
 112 __clear_user(void *to, unsigned long n)
 113 {
 114         __check_locks(1);
 115         __do_clear_user(to, n);
 116         return n;
 117 }
 118
 119 /*
 120  * Return the size of a string (including the ending 0)
 121  *
 122  * Return 0 for error
 123  */
 124
 125 long strlen_user(const char *s)
 126 {
 127         unsigned long res;
 128
 129         __check_locks(1);
 130         __asm__ __volatile__(
 131                 "0:     repne; scasb\n"
 132                 "       notl %0\n"
 133                 "1:\n"
 134                 ".section .fixup,\"ax\"\n"
 135                 "2:     xorl %0,%0\n"
 136                 "       jmp 1b\n"
 137                 ".previous\n"
 138                 ".section __ex_table,\"a\"\n"
 139                 "       .align 4\n"
 140                 "       .long 0b,2b\n"
 141                 ".previous"
 142                 :"=c" (res), "=D" (s)
 143                 :"1" (s), "a" (0), "0" (-__addr_ok(s)));
 144         return res & -__addr_ok(s);
 145 }