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   1 #ifndef __LINUX_UACCESS_H__
   2 #define __LINUX_UACCESS_H__
   3
   4 #include <asm/uaccess.h>
   5
   6 #ifndef ARCH_HAS_NOCACHE_UACCESS
   7
   8 static inline unsigned long __copy_from_user_inatomic_nocache(void *to,
   9                                 const void __user *from, unsigned long n)
  10 {
  11         return __copy_from_user_inatomic(to, from, n);
  12 }
  13
  14 static inline unsigned long __copy_from_user_nocache(void *to,
  15                                 const void __user *from, unsigned long n)
  16 {
  17         return __copy_from_user(to, from, n);
  18 }
  19
  20 #endif          /* ARCH_HAS_NOCACHE_UACCESS */
  21
  22 /**
  23  * probe_kernel_address(): safely attempt to read from a location
  24  * @addr: address to read from - its type is type typeof(retval)*
  25  * @retval: read into this variable
  26  *
  27  * Safely read from address @addr into variable @revtal.  If a kernel fault
  28  * happens, handle that and return -EFAULT.
  29  * We ensure that the __get_user() is executed in atomic context so that
  30  * do_page_fault() doesn't attempt to take mmap_sem.  This makes
  31  * probe_kernel_address() suitable for use within regions where the caller
  32  * already holds mmap_sem, or other locks which nest inside mmap_sem.
  33  */
  34 #define probe_kernel_address(addr, retval)              \
  35         ({                                              \
  36                 long ret;                               \
  37                                                         \
  38                 inc_preempt_count();                    \
  39                 ret = __get_user(retval, addr);         \
  40                 dec_preempt_count();                    \
  41                 ret;                                    \
  42         })
  43
  44 #endif          /* __LINUX_UACCESS_H__ */