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 <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