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/string.h>
  10 #include <asm/asm.h>
  11 #include <asm/page.h>
  12
  13 unsigned long __must_check __copy_to_user_ll
  14                 (void __user *to, const void *from, unsigned long n);
  15 unsigned long __must_check __copy_from_user_ll
  16                 (void *to, const void __user *from, unsigned long n);
  17 unsigned long __must_check __copy_from_user_ll_nozero
  18                 (void *to, const void __user *from, unsigned long n);
  19 unsigned long __must_check __copy_from_user_ll_nocache
  20                 (void *to, const void __user *from, unsigned long n);
  21 unsigned long __must_check __copy_from_user_ll_nocache_nozero
  22                 (void *to, const void __user *from, unsigned long n);
  23
  24 /**
  25  * __copy_to_user_inatomic: - Copy a block of data into user space, with less checking.
  26  * @to:   Destination address, in user space.
  27  * @from: Source address, in kernel space.
  28  * @n:    Number of bytes to copy.
  29  *
  30  * Context: User context only.
  31  *
  32  * Copy data from kernel space to user space.  Caller must check
  33  * the specified block with access_ok() before calling this function.
  34  * The caller should also make sure he pins the user space address
  35  * so that we don't result in page fault and sleep.
  36  *
  37  * Here we special-case 1, 2 and 4-byte copy_*_user invocations.  On a fault
  38  * we return the initial request size (1, 2 or 4), as copy_*_user should do.
  39  * If a store crosses a page boundary and gets a fault, the x86 will not write
  40  * anything, so this is accurate.
  41  */
  42
  43 static __always_inline unsigned long __must_check
  44 __copy_to_user_inatomic(void __user *to, const void *from, unsigned long n)
  45 {
  46         if (__builtin_constant_p(n)) {
  47                 unsigned long ret;
  48
  49                 switch (n) {
  50                 case 1:
  51                         __put_user_size(*(u8 *)from, (u8 __user *)to,
  52                                         1, ret, 1);
  53                         return ret;
  54                 case 2:
  55                         __put_user_size(*(u16 *)from, (u16 __user *)to,
  56                                         2, ret, 2);
  57                         return ret;
  58                 case 4:
  59                         __put_user_size(*(u32 *)from, (u32 __user *)to,
  60                                         4, ret, 4);
  61                         return ret;
  62                 case 8:
  63                         __put_user_size(*(u64 *)from, (u64 __user *)to,
  64                                         8, ret, 8);
  65                         return ret;
  66                 }
  67         }
  68         return __copy_to_user_ll(to, from, n);
  69 }
  70
  71 /**
  72  * __copy_to_user: - Copy a block of data into user space, with less checking.
  73  * @to:   Destination address, in user space.
  74  * @from: Source address, in kernel space.
  75  * @n:    Number of bytes to copy.
  76  *
  77  * Context: User context only. This function may sleep if pagefaults are
  78  *          enabled.
  79  *
  80  * Copy data from kernel space to user space.  Caller must check
  81  * the specified block with access_ok() before calling this function.
  82  *
  83  * Returns number of bytes that could not be copied.
  84  * On success, this will be zero.
  85  */
  86 static __always_inline unsigned long __must_check
  87 __copy_to_user(void __user *to, const void *from, unsigned long n)
  88 {
  89         might_fault();
  90         return __copy_to_user_inatomic(to, from, n);
  91 }
  92
  93 static __always_inline unsigned long
  94 __copy_from_user_inatomic(void *to, const void __user *from, unsigned long n)
  95 {
  96         /* Avoid zeroing the tail if the copy fails..
  97          * If 'n' is constant and 1, 2, or 4, we do still zero on a failure,
  98          * but as the zeroing behaviour is only significant when n is not
  99          * constant, that shouldn't be a problem.
 100          */
 101         if (__builtin_constant_p(n)) {
 102                 unsigned long ret;
 103
 104                 switch (n) {
 105                 case 1:
 106                         __get_user_size(*(u8 *)to, from, 1, ret, 1);
 107                         return ret;
 108                 case 2:
 109                         __get_user_size(*(u16 *)to, from, 2, ret, 2);
 110                         return ret;
 111                 case 4:
 112                         __get_user_size(*(u32 *)to, from, 4, ret, 4);
 113                         return ret;
 114                 }
 115         }
 116         return __copy_from_user_ll_nozero(to, from, n);
 117 }
 118
 119 /**
 120  * __copy_from_user: - Copy a block of data from user space, with less checking.
 121  * @to:   Destination address, in kernel space.
 122  * @from: Source address, in user space.
 123  * @n:    Number of bytes to copy.
 124  *
 125  * Context: User context only. This function may sleep if pagefaults are
 126  *          enabled.
 127  *
 128  * Copy data from user space to kernel space.  Caller must check
 129  * the specified block with access_ok() before calling this function.
 130  *
 131  * Returns number of bytes that could not be copied.
 132  * On success, this will be zero.
 133  *
 134  * If some data could not be copied, this function will pad the copied
 135  * data to the requested size using zero bytes.
 136  *
 137  * An alternate version - __copy_from_user_inatomic() - may be called from
 138  * atomic context and will fail rather than sleep.  In this case the
 139  * uncopied bytes will *NOT* be padded with zeros.  See fs/filemap.h
 140  * for explanation of why this is needed.
 141  */
 142 static __always_inline unsigned long
 143 __copy_from_user(void *to, const void __user *from, unsigned long n)
 144 {
 145         might_fault();
 146         if (__builtin_constant_p(n)) {
 147                 unsigned long ret;
 148
 149                 switch (n) {
 150                 case 1:
 151                         __get_user_size(*(u8 *)to, from, 1, ret, 1);
 152                         return ret;
 153                 case 2:
 154                         __get_user_size(*(u16 *)to, from, 2, ret, 2);
 155                         return ret;
 156                 case 4:
 157                         __get_user_size(*(u32 *)to, from, 4, ret, 4);
 158                         return ret;
 159                 }
 160         }
 161         return __copy_from_user_ll(to, from, n);
 162 }
 163
 164 static __always_inline unsigned long __copy_from_user_nocache(void *to,
 165                                 const void __user *from, unsigned long n)
 166 {
 167         might_fault();
 168         if (__builtin_constant_p(n)) {
 169                 unsigned long ret;
 170
 171                 switch (n) {
 172                 case 1:
 173                         __get_user_size(*(u8 *)to, from, 1, ret, 1);
 174                         return ret;
 175                 case 2:
 176                         __get_user_size(*(u16 *)to, from, 2, ret, 2);
 177                         return ret;
 178                 case 4:
 179                         __get_user_size(*(u32 *)to, from, 4, ret, 4);
 180                         return ret;
 181                 }
 182         }
 183         return __copy_from_user_ll_nocache(to, from, n);
 184 }
 185
 186 static __always_inline unsigned long
 187 __copy_from_user_inatomic_nocache(void *to, const void __user *from,
 188                                   unsigned long n)
 189 {
 190        return __copy_from_user_ll_nocache_nozero(to, from, n);
 191 }
 192
 193 #endif /* _ASM_X86_UACCESS_32_H */