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