#ifndef ASM_X86__UACCESS_H
  #define ASM_X86__UACCESS_H

  /*
   * User space memory access functions
   */
  #include <linux/errno.h>
  #include <linux/compiler.h>
  #include <linux/thread_info.h>
  #include <linux/prefetch.h>
  #include <linux/string.h>
  #include <asm/asm.h>
  #include <asm/page.h>
  
  #define VERIFY_READ 0
  #define VERIFY_WRITE 1
  
  /*
   * The fs value determines whether argument validity checking should be
   * performed or not.  If get_fs() == USER_DS, checking is performed, with
   * get_fs() == KERNEL_DS, checking is bypassed.
   *
   * For historical reasons, these macros are grossly misnamed.
   */
  
  #define MAKE_MM_SEG(s)	((mm_segment_t) { (s) })
  
  #define KERNEL_DS	MAKE_MM_SEG(-1UL)
  #define USER_DS		MAKE_MM_SEG(PAGE_OFFSET)
  
  #define get_ds()	(KERNEL_DS)
  #define get_fs()	(current_thread_info()->addr_limit)
  #define set_fs(x)	(current_thread_info()->addr_limit = (x))
  
  #define segment_eq(a, b)	((a).seg == (b).seg)

  #define __addr_ok(addr)					\
  	((unsigned long __force)(addr) <		\
  	 (current_thread_info()->addr_limit.seg))

  /*
   * Test whether a block of memory is a valid user space address.
   * Returns 0 if the range is valid, nonzero otherwise.
   *
   * This is equivalent to the following test:
   * (u33)addr + (u33)size >= (u33)current->addr_limit.seg (u65 for x86_64)
   *
   * This needs 33-bit (65-bit for x86_64) arithmetic. We have a carry...
   */
  
  #define __range_not_ok(addr, size)					\
  ({									\
  	unsigned long flag, roksum;					\
  	__chk_user_ptr(addr);						\
  	asm("add %3,%1 ; sbb %0,%0 ; cmp %1,%4 ; sbb $0,%0"		\
  	    : "=&r" (flag), "=r" (roksum)				\
  	    : "1" (addr), "g" ((long)(size)),				\
  	      "rm" (current_thread_info()->addr_limit.seg));		\
  	flag;								\
  })
  
  /**
   * access_ok: - Checks if a user space pointer is valid
   * @type: Type of access: %VERIFY_READ or %VERIFY_WRITE.  Note that
   *        %VERIFY_WRITE is a superset of %VERIFY_READ - if it is safe
   *        to write to a block, it is always safe to read from it.
   * @addr: User space pointer to start of block to check
   * @size: Size of block to check
   *
   * Context: User context only.  This function may sleep.
   *
   * Checks if a pointer to a block of memory in user space is valid.
   *
   * Returns true (nonzero) if the memory block may be valid, false (zero)
   * if it is definitely invalid.
   *
   * Note that, depending on architecture, this function probably just
   * checks that the pointer is in the user space range - after calling
   * this function, memory access functions may still return -EFAULT.
   */
  #define access_ok(type, addr, size) (likely(__range_not_ok(addr, size) == 0))
  
  /*
   * The exception table consists of pairs of addresses: the first is the
   * address of an instruction that is allowed to fault, and the second is
   * the address at which the program should continue.  No registers are
   * modified, so it is entirely up to the continuation code to figure out
   * what to do.
   *
   * All the routines below use bits of fixup code that are out of line
   * with the main instruction path.  This means when everything is well,
   * we don't even have to jump over them.  Further, they do not intrude
   * on our cache or tlb entries.
   */
  
  struct exception_table_entry {
  	unsigned long insn, fixup;
  };
  
  extern int fixup_exception(struct pt_regs *regs);
  
  /*
   * These are the main single-value transfer routines.  They automatically
   * use the right size if we just have the right pointer type.
   *
   * This gets kind of ugly. We want to return _two_ values in "get_user()"
   * and yet we don't want to do any pointers, because that is too much
   * of a performance impact. Thus we have a few rather ugly macros here,
   * and hide all the ugliness from the user.
   *
   * The "__xxx" versions of the user access functions are versions that
   * do not verify the address space, that must have been done previously
   * with a separate "access_ok()" call (this is used when we do multiple
   * accesses to the same area of user memory).
   */
  
  extern int __get_user_1(void);
  extern int __get_user_2(void);
  extern int __get_user_4(void);
  extern int __get_user_8(void);
  extern int __get_user_bad(void);
  
  #define __get_user_x(size, ret, x, ptr)		      \
  	asm volatile("call __get_user_" #size	      \
  		     : "=a" (ret),"=d" (x)	      \
  		     : "0" (ptr))		      \

  /* Careful: we have to cast the result to the type of the pointer
   * for sign reasons */
  
  /**
   * get_user: - Get a simple variable from user space.
   * @x:   Variable to store result.
   * @ptr: Source address, in user space.
   *
   * Context: User context only.  This function may sleep.
   *
   * This macro copies a single simple variable from user space to kernel
   * space.  It supports simple types like char and int, but not larger
   * data types like structures or arrays.
   *
   * @ptr must have pointer-to-simple-variable type, and the result of
   * dereferencing @ptr must be assignable to @x without a cast.
   *
   * Returns zero on success, or -EFAULT on error.
   * On error, the variable @x is set to zero.
   */
  #ifdef CONFIG_X86_32
  #define __get_user_8(__ret_gu, __val_gu, ptr)				\
  		__get_user_x(X, __ret_gu, __val_gu, ptr)
  #else
  #define __get_user_8(__ret_gu, __val_gu, ptr)				\
  		__get_user_x(8, __ret_gu, __val_gu, ptr)
  #endif
  
  #define get_user(x, ptr)						\
  ({									\
  	int __ret_gu;							\
  	unsigned long __val_gu;						\
  	__chk_user_ptr(ptr);						\
  	switch (sizeof(*(ptr))) {					\
  	case 1:								\
  		__get_user_x(1, __ret_gu, __val_gu, ptr);		\
  		break;							\
  	case 2:								\
  		__get_user_x(2, __ret_gu, __val_gu, ptr);		\
  		break;							\
  	case 4:								\
  		__get_user_x(4, __ret_gu, __val_gu, ptr);		\
  		break;							\
  	case 8:								\
  		__get_user_8(__ret_gu, __val_gu, ptr);			\
  		break;							\
  	default:							\
  		__get_user_x(X, __ret_gu, __val_gu, ptr);		\
  		break;							\
  	}								\
  	(x) = (__typeof__(*(ptr)))__val_gu;				\
  	__ret_gu;							\
  })

  #define __put_user_x(size, x, ptr, __ret_pu)			\
  	asm volatile("call __put_user_" #size : "=a" (__ret_pu)	\
  		     :"0" ((typeof(*(ptr)))(x)), "c" (ptr) : "ebx")

  #ifdef CONFIG_X86_32
  #define __put_user_u64(x, addr, err)					\
  	asm volatile("1:	movl %%eax,0(%2)
  "			\
  		     "2:	movl %%edx,4(%2)
  "			\
  		     "3:
  "						\
  		     ".section .fixup,\"ax\"
  "				\
  		     "4:	movl %3,%0
  "				\
  		     "	jmp 3b
  "					\
  		     ".previous
  "					\
  		     _ASM_EXTABLE(1b, 4b)				\
  		     _ASM_EXTABLE(2b, 4b)				\
  		     : "=r" (err)					\
  		     : "A" (x), "r" (addr), "i" (-EFAULT), "0" (err))

  
  #define __put_user_x8(x, ptr, __ret_pu)				\
  	asm volatile("call __put_user_8" : "=a" (__ret_pu)	\
  		     : "A" ((typeof(*(ptr)))(x)), "c" (ptr) : "ebx")

  #else
  #define __put_user_u64(x, ptr, retval) \
  	__put_user_asm(x, ptr, retval, "q", "", "Zr", -EFAULT)

  #define __put_user_x8(x, ptr, __ret_pu) __put_user_x(8, x, ptr, __ret_pu)

  #endif

  extern void __put_user_bad(void);
  
  /*
   * Strange magic calling convention: pointer in %ecx,
   * value in %eax(:%edx), return value in %eax. clobbers %rbx
   */
  extern void __put_user_1(void);
  extern void __put_user_2(void);
  extern void __put_user_4(void);
  extern void __put_user_8(void);

  #ifdef CONFIG_X86_WP_WORKS_OK

  /**
   * put_user: - Write a simple value into user space.
   * @x:   Value to copy to user space.
   * @ptr: Destination address, in user space.
   *
   * Context: User context only.  This function may sleep.
   *
   * This macro copies a single simple value from kernel space to user
   * space.  It supports simple types like char and int, but not larger
   * data types like structures or arrays.
   *
   * @ptr must have pointer-to-simple-variable type, and @x must be assignable
   * to the result of dereferencing @ptr.
   *
   * Returns zero on success, or -EFAULT on error.
   */
  #define put_user(x, ptr)					\
  ({								\
  	int __ret_pu;						\
  	__typeof__(*(ptr)) __pu_val;				\
  	__chk_user_ptr(ptr);					\
  	__pu_val = x;						\
  	switch (sizeof(*(ptr))) {				\
  	case 1:							\
  		__put_user_x(1, __pu_val, ptr, __ret_pu);	\
  		break;						\
  	case 2:							\
  		__put_user_x(2, __pu_val, ptr, __ret_pu);	\
  		break;						\
  	case 4:							\
  		__put_user_x(4, __pu_val, ptr, __ret_pu);	\
  		break;						\
  	case 8:							\
  		__put_user_x8(__pu_val, ptr, __ret_pu);		\
  		break;						\
  	default:						\
  		__put_user_x(X, __pu_val, ptr, __ret_pu);	\
  		break;						\
  	}							\
  	__ret_pu;						\
  })

  #define __put_user_size(x, ptr, size, retval, errret)			\
  do {									\
  	retval = 0;							\
  	__chk_user_ptr(ptr);						\
  	switch (size) {							\
  	case 1:								\
  		__put_user_asm(x, ptr, retval, "b", "b", "iq", errret);	\
  		break;							\
  	case 2:								\
  		__put_user_asm(x, ptr, retval, "w", "w", "ir", errret);	\
  		break;							\
  	case 4:								\
  		__put_user_asm(x, ptr, retval, "l", "k",  "ir", errret);\
  		break;							\
  	case 8:								\
  		__put_user_u64((__typeof__(*ptr))(x), ptr, retval);	\
  		break;							\
  	default:							\
  		__put_user_bad();					\
  	}								\
  } while (0)
  
  #else
  
  #define __put_user_size(x, ptr, size, retval, errret)			\
  do {									\
  	__typeof__(*(ptr))__pus_tmp = x;				\
  	retval = 0;							\
  									\
  	if (unlikely(__copy_to_user_ll(ptr, &__pus_tmp, size) != 0))	\
  		retval = errret;					\
  } while (0)

  #define put_user(x, ptr)					\
  ({								\
  	int __ret_pu;						\
  	__typeof__(*(ptr))__pus_tmp = x;			\
  	__ret_pu = 0;						\
  	if (unlikely(__copy_to_user_ll(ptr, &__pus_tmp,		\
  				       sizeof(*(ptr))) != 0))	\
  		__ret_pu = -EFAULT;				\
  	__ret_pu;						\
  })

  #endif

  #ifdef CONFIG_X86_32
  #define __get_user_asm_u64(x, ptr, retval, errret)	(x) = __get_user_bad()
  #else
  #define __get_user_asm_u64(x, ptr, retval, errret) \
  	 __get_user_asm(x, ptr, retval, "q", "", "=r", errret)
  #endif
  
  #define __get_user_size(x, ptr, size, retval, errret)			\
  do {									\
  	retval = 0;							\
  	__chk_user_ptr(ptr);						\
  	switch (size) {							\
  	case 1:								\
  		__get_user_asm(x, ptr, retval, "b", "b", "=q", errret);	\
  		break;							\
  	case 2:								\
  		__get_user_asm(x, ptr, retval, "w", "w", "=r", errret);	\
  		break;							\
  	case 4:								\
  		__get_user_asm(x, ptr, retval, "l", "k", "=r", errret);	\
  		break;							\
  	case 8:								\
  		__get_user_asm_u64(x, ptr, retval, errret);		\
  		break;							\
  	default:							\
  		(x) = __get_user_bad();					\
  	}								\
  } while (0)
  
  #define __get_user_asm(x, addr, err, itype, rtype, ltype, errret)	\
  	asm volatile("1:	mov"itype" %2,%"rtype"1
  "		\
  		     "2:
  "						\
  		     ".section .fixup,\"ax\"
  "				\
  		     "3:	mov %3,%0
  "				\
  		     "	xor"itype" %"rtype"1,%"rtype"1
  "		\
  		     "	jmp 2b
  "					\
  		     ".previous
  "					\
  		     _ASM_EXTABLE(1b, 3b)				\
  		     : "=r" (err), ltype(x)				\
  		     : "m" (__m(addr)), "i" (errret), "0" (err))

  #define __put_user_nocheck(x, ptr, size)			\
  ({								\
  	long __pu_err;						\
  	__put_user_size((x), (ptr), (size), __pu_err, -EFAULT);	\
  	__pu_err;						\
  })

  #define __get_user_nocheck(x, ptr, size)				\
  ({									\
  	long __gu_err;							\
  	unsigned long __gu_val;						\
  	__get_user_size(__gu_val, (ptr), (size), __gu_err, -EFAULT);	\
  	(x) = (__force __typeof__(*(ptr)))__gu_val;			\
  	__gu_err;							\
  })

  
  /* FIXME: this hack is definitely wrong -AK */
  struct __large_struct { unsigned long buf[100]; };
  #define __m(x) (*(struct __large_struct __user *)(x))
  
  /*
   * Tell gcc we read from memory instead of writing: this is because
   * we do not write to any memory gcc knows about, so there are no
   * aliasing issues.
   */
  #define __put_user_asm(x, addr, err, itype, rtype, ltype, errret)	\
  	asm volatile("1:	mov"itype" %"rtype"1,%2
  "		\
  		     "2:
  "						\
  		     ".section .fixup,\"ax\"
  "				\
  		     "3:	mov %3,%0
  "				\
  		     "	jmp 2b
  "					\
  		     ".previous
  "					\
  		     _ASM_EXTABLE(1b, 3b)				\
  		     : "=r"(err)					\
  		     : ltype(x), "m" (__m(addr)), "i" (errret), "0" (err))

  /**
   * __get_user: - Get a simple variable from user space, with less checking.
   * @x:   Variable to store result.
   * @ptr: Source address, in user space.
   *
   * Context: User context only.  This function may sleep.
   *
   * This macro copies a single simple variable from user space to kernel
   * space.  It supports simple types like char and int, but not larger
   * data types like structures or arrays.
   *
   * @ptr must have pointer-to-simple-variable type, and the result of
   * dereferencing @ptr must be assignable to @x without a cast.
   *
   * Caller must check the pointer with access_ok() before calling this
   * function.
   *
   * Returns zero on success, or -EFAULT on error.
   * On error, the variable @x is set to zero.
   */
  
  #define __get_user(x, ptr)						\
  	__get_user_nocheck((x), (ptr), sizeof(*(ptr)))
  /**
   * __put_user: - Write a simple value into user space, with less checking.
   * @x:   Value to copy to user space.
   * @ptr: Destination address, in user space.
   *
   * Context: User context only.  This function may sleep.
   *
   * This macro copies a single simple value from kernel space to user
   * space.  It supports simple types like char and int, but not larger
   * data types like structures or arrays.
   *
   * @ptr must have pointer-to-simple-variable type, and @x must be assignable
   * to the result of dereferencing @ptr.
   *
   * Caller must check the pointer with access_ok() before calling this
   * function.
   *
   * Returns zero on success, or -EFAULT on error.
   */
  
  #define __put_user(x, ptr)						\
  	__put_user_nocheck((__typeof__(*(ptr)))(x), (ptr), sizeof(*(ptr)))

  #define __get_user_unaligned __get_user
  #define __put_user_unaligned __put_user

  /*
   * movsl can be slow when source and dest are not both 8-byte aligned
   */
  #ifdef CONFIG_X86_INTEL_USERCOPY
  extern struct movsl_mask {
  	int mask;
  } ____cacheline_aligned_in_smp movsl_mask;
  #endif

  #define ARCH_HAS_NOCACHE_UACCESS 1

  #ifdef CONFIG_X86_32
  # include "uaccess_32.h"
  #else

  # define ARCH_HAS_SEARCH_EXTABLE

  # include "uaccess_64.h"
  #endif

  #endif /* ASM_X86__UACCESS_H */