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 static __always_inline unsigned long __must_check
  38 __copy_to_user_inatomic(void __user *to, const void *from, unsigned long n)
  39 {
  40         return __copy_to_user_ll(to, from, n);
  41 }
  42
  43 /**
  44  * __copy_to_user: - Copy a block of data into user space, with less checking.
  45  * @to:   Destination address, in user space.
  46  * @from: Source address, in kernel space.
  47  * @n:    Number of bytes to copy.
  48  *
  49  * Context: User context only. This function may sleep if pagefaults are
  50  *          enabled.
  51  *
  52  * Copy data from kernel space to user space.  Caller must check
  53  * the specified block with access_ok() before calling this function.
  54  *
  55  * Returns number of bytes that could not be copied.
  56  * On success, this will be zero.
  57  */
  58 static __always_inline unsigned long __must_check
  59 __copy_to_user(void __user *to, const void *from, unsigned long n)
  60 {
  61         might_fault();
  62         return __copy_to_user_inatomic(to, from, n);
  63 }
  64
  65 static __always_inline unsigned long
  66 __copy_from_user_inatomic(void *to, const void __user *from, unsigned long n)
  67 {
  68         return __copy_from_user_ll_nozero(to, from, n);
  69 }
  70
  71 /**
  72  * __copy_from_user: - Copy a block of data from user space, with less checking.
  73  * @to:   Destination address, in kernel space.
  74  * @from: Source address, in user 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 user space to kernel 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  * If some data could not be copied, this function will pad the copied
  87  * data to the requested size using zero bytes.
  88  *
  89  * An alternate version - __copy_from_user_inatomic() - may be called from
  90  * atomic context and will fail rather than sleep.  In this case the
  91  * uncopied bytes will *NOT* be padded with zeros.  See fs/filemap.h
  92  * for explanation of why this is needed.
  93  */
  94 static __always_inline unsigned long
  95 __copy_from_user(void *to, const void __user *from, unsigned long n)
  96 {
  97         might_fault();
  98         if (__builtin_constant_p(n)) {
  99                 unsigned long ret;
 100
 101                 switch (n) {
 102                 case 1:
 103                         __uaccess_begin();
 104                         __get_user_size(*(u8 *)to, from, 1, ret, 1);
 105                         __uaccess_end();
 106                         return ret;
 107                 case 2:
 108                         __uaccess_begin();
 109                         __get_user_size(*(u16 *)to, from, 2, ret, 2);
 110                         __uaccess_end();
 111                         return ret;
 112                 case 4:
 113                         __uaccess_begin();
 114                         __get_user_size(*(u32 *)to, from, 4, ret, 4);
 115                         __uaccess_end();
 116                         return ret;
 117                 }
 118         }
 119         return __copy_from_user_ll(to, from, n);
 120 }
 121
 122 static __always_inline unsigned long __copy_from_user_nocache(void *to,
 123                                 const void __user *from, unsigned long n)
 124 {
 125         might_fault();
 126         if (__builtin_constant_p(n)) {
 127                 unsigned long ret;
 128
 129                 switch (n) {
 130                 case 1:
 131                         __uaccess_begin();
 132                         __get_user_size(*(u8 *)to, from, 1, ret, 1);
 133                         __uaccess_end();
 134                         return ret;
 135                 case 2:
 136                         __uaccess_begin();
 137                         __get_user_size(*(u16 *)to, from, 2, ret, 2);
 138                         __uaccess_end();
 139                         return ret;
 140                 case 4:
 141                         __uaccess_begin();
 142                         __get_user_size(*(u32 *)to, from, 4, ret, 4);
 143                         __uaccess_end();
 144                         return ret;
 145                 }
 146         }
 147         return __copy_from_user_ll_nocache(to, from, n);
 148 }
 149
 150 static __always_inline unsigned long
 151 __copy_from_user_inatomic_nocache(void *to, const void __user *from,
 152                                   unsigned long n)
 153 {
 154        return __copy_from_user_ll_nocache_nozero(to, from, n);
 155 }
 156
 157 #endif /* _ASM_X86_UACCESS_32_H */