arch/x86/include/asm/uaccess_32.h

   1 #ifndef _ASM_X86_UACCESS_32_H
   2 #define _ASM_X86_UACCESS_32_H
   3
   4 /*
   5  * User space memory access functions
   6  */
   7 #include <linux/errno.h>
   8 #include <linux/thread_info.h>
   9 #include <linux/prefetch.h>
  10 #include <linux/string.h>
  11 #include <asm/asm.h>
  12 #include <asm/page.h>
  13
  14 unsigned long __must_check __copy_to_user_ll
  15                 (void __user *to, const void *from, unsigned long n);
  16 unsigned long __must_check __copy_from_user_ll
  17                 (void *to, const void __user *from, unsigned long n);
  18 unsigned long __must_check __copy_from_user_ll_nozero
  19                 (void *to, const void __user *from, unsigned long n);
  20 unsigned long __must_check __copy_from_user_ll_nocache
  21                 (void *to, const void __user *from, unsigned long n);
  22 unsigned long __must_check __copy_from_user_ll_nocache_nozero
  23                 (void *to, const void __user *from, unsigned long n);
  24
  25 /**
  26  * __copy_to_user_inatomic: - Copy a block of data into user space, with less checking.
  27  * @to:   Destination address, in user space.
  28  * @from: Source address, in kernel space.
  29  * @n:    Number of bytes to copy.
  30  *
  31  * Context: User context only.
  32  *
  33  * Copy data from kernel space to user space.  Caller must check
  34  * the specified block with access_ok() before calling this function.
  35  * The caller should also make sure he pins the user space address
  36  * so that we don't result in page fault and sleep.
  37  *
  38  * Here we special-case 1, 2 and 4-byte copy_*_user invocations.  On a fault
  39  * we return the initial request size (1, 2 or 4), as copy_*_user should do.
  40  * If a store crosses a page boundary and gets a fault, the x86 will not write
  41  * anything, so this is accurate.
  42  */
  43
  44 static __always_inline unsigned long __must_check
  45 __copy_to_user_inatomic(void __user *to, const void *from, unsigned long n)
  46 {
  47         if (__builtin_constant_p(n)) {
  48                 unsigned long ret;
  49
  50                 switch (n) {
  51                 case 1:
  52                         __put_user_size(*(u8 *)from, (u8 __user *)to,
  53                                         1, ret, 1);
  54                         return ret;
  55                 case 2:
  56                         __put_user_size(*(u16 *)from, (u16 __user *)to,
  57                                         2, ret, 2);
  58                         return ret;
  59                 case 4:
  60                         __put_user_size(*(u32 *)from, (u32 __user *)to,
  61                                         4, ret, 4);
  62                         return ret;
  63                 }
  64         }
  65         return __copy_to_user_ll(to, from, n);
  66 }
  67
  68 /**
  69  * __copy_to_user: - Copy a block of data into user space, with less checking.
  70  * @to:   Destination address, in user space.
  71  * @from: Source address, in kernel space.
  72  * @n:    Number of bytes to copy.
  73  *
  74  * Context: User context only.  This function may sleep.
  75  *
  76  * Copy data from kernel space to user space.  Caller must check
  77  * the specified block with access_ok() before calling this function.
  78  *
  79  * Returns number of bytes that could not be copied.
  80  * On success, this will be zero.
  81  */
  82 static __always_inline unsigned long __must_check
  83 __copy_to_user(void __user *to, const void *from, unsigned long n)
  84 {
  85         might_fault();
  86         return __copy_to_user_inatomic(to, from, n);
  87 }
  88
  89 static __always_inline unsigned long
  90 __copy_from_user_inatomic(void *to, const void __user *from, unsigned long n)
  91 {
  92         /* Avoid zeroing the tail if the copy fails..
  93          * If 'n' is constant and 1, 2, or 4, we do still zero on a failure,
  94          * but as the zeroing behaviour is only significant when n is not
  95          * constant, that shouldn't be a problem.
  96          */
  97         if (__builtin_constant_p(n)) {
  98                 unsigned long ret;
  99
 100                 switch (n) {
 101                 case 1:
 102                         __get_user_size(*(u8 *)to, from, 1, ret, 1);
 103                         return ret;
 104                 case 2:
 105                         __get_user_size(*(u16 *)to, from, 2, ret, 2);
 106                         return ret;
 107                 case 4:
 108                         __get_user_size(*(u32 *)to, from, 4, ret, 4);
 109                         return ret;
 110                 }
 111         }
 112         return __copy_from_user_ll_nozero(to, from, n);
 113 }
 114
 115 /**
 116  * __copy_from_user: - Copy a block of data from user space, with less checking.
 117  * @to:   Destination address, in kernel space.
 118  * @from: Source address, in user space.
 119  * @n:    Number of bytes to copy.
 120  *
 121  * Context: User context only.  This function may sleep.
 122  *
 123  * Copy data from user space to kernel space.  Caller must check
 124  * the specified block with access_ok() before calling this function.
 125  *
 126  * Returns number of bytes that could not be copied.
 127  * On success, this will be zero.
 128  *
 129  * If some data could not be copied, this function will pad the copied
 130  * data to the requested size using zero bytes.
 131  *
 132  * An alternate version - __copy_from_user_inatomic() - may be called from
 133  * atomic context and will fail rather than sleep.  In this case the
 134  * uncopied bytes will *NOT* be padded with zeros.  See fs/filemap.h
 135  * for explanation of why this is needed.
 136  */
 137 static __always_inline unsigned long
 138 __copy_from_user(void *to, const void __user *from, unsigned long n)
 139 {
 140         might_fault();
 141         if (__builtin_constant_p(n)) {
 142                 unsigned long ret;
 143
 144                 switch (n) {
 145                 case 1:
 146                         __get_user_size(*(u8 *)to, from, 1, ret, 1);
 147                         return ret;
 148                 case 2:
 149                         __get_user_size(*(u16 *)to, from, 2, ret, 2);
 150                         return ret;
 151                 case 4:
 152                         __get_user_size(*(u32 *)to, from, 4, ret, 4);
 153                         return ret;
 154                 }
 155         }
 156         return __copy_from_user_ll(to, from, n);
 157 }
 158
 159 static __always_inline unsigned long __copy_from_user_nocache(void *to,
 160                                 const void __user *from, unsigned long n)
 161 {
 162         might_fault();
 163         if (__builtin_constant_p(n)) {
 164                 unsigned long ret;
 165
 166                 switch (n) {
 167                 case 1:
 168                         __get_user_size(*(u8 *)to, from, 1, ret, 1);
 169                         return ret;
 170                 case 2:
 171                         __get_user_size(*(u16 *)to, from, 2, ret, 2);
 172                         return ret;
 173                 case 4:
 174                         __get_user_size(*(u32 *)to, from, 4, ret, 4);
 175                         return ret;
 176                 }
 177         }
 178         return __copy_from_user_ll_nocache(to, from, n);
 179 }
 180
 181 static __always_inline unsigned long
 182 __copy_from_user_inatomic_nocache(void *to, const void __user *from,
 183                                   unsigned long n)
 184 {
 185        return __copy_from_user_ll_nocache_nozero(to, from, n);
 186 }
 187
 188 unsigned long __must_check copy_to_user(void __user *to,
 189                                         const void *from, unsigned long n);
 190 unsigned long __must_check copy_from_user(void *to,
 191                                           const void __user *from,
 192                                           unsigned long n);
 193 long __must_check strncpy_from_user(char *dst, const char __user *src,
 194                                     long count);
 195 long __must_check __strncpy_from_user(char *dst,
 196                                       const char __user *src, long count);
 197
 198 /**
 199  * strlen_user: - Get the size of a string in user space.
 200  * @str: The string to measure.
 201  *
 202  * Context: User context only.  This function may sleep.
 203  *
 204  * Get the size of a NUL-terminated string in user space.
 205  *
 206  * Returns the size of the string INCLUDING the terminating NUL.
 207  * On exception, returns 0.
 208  *
 209  * If there is a limit on the length of a valid string, you may wish to
 210  * consider using strnlen_user() instead.
 211  */
 212 #define strlen_user(str) strnlen_user(str, LONG_MAX)
 213
 214 long strnlen_user(const char __user *str, long n);
 215 unsigned long __must_check clear_user(void __user *mem, unsigned long len);
 216 unsigned long __must_check __clear_user(void __user *mem, unsigned long len);
 217
 218 #endif /* _ASM_X86_UACCESS_32_H */