text: #ifndef _ASM_IA64_UACCESS_H
  #define _ASM_IA64_UACCESS_H
  
  /*
   * This file defines various macros to transfer memory areas across
   * the user/kernel boundary.  This needs to be done carefully because
   * this code is executed in kernel mode and uses user-specified
   * addresses.  Thus, we need to be careful not to let the user to
   * trick us into accessing kernel memory that would normally be
   * inaccessible.  This code is also fairly performance sensitive,
   * so we want to spend as little time doing safety checks as
   * possible.
   *
   * To make matters a bit more interesting, these macros sometimes also
   * called from within the kernel itself, in which case the address
   * validity check must be skipped.  The get_fs() macro tells us what
   * to do: if get_fs()==USER_DS, checking is performed, if
   * get_fs()==KERNEL_DS, checking is bypassed.
   *
   * Note that even if the memory area specified by the user is in a
   * valid address range, it is still possible that we'll get a page
   * fault while accessing it.  This is handled by filling out an
   * exception handler fixup entry for each instruction that has the
   * potential to fault.  When such a fault occurs, the page fault
   * handler checks to see whether the faulting instruction has a fixup
   * associated and, if so, sets r8 to -EFAULT and clears r9 to 0 and
   * then resumes execution at the continuation point.
   *
   * Based on <asm-alpha/uaccess.h>.
   *
   * Copyright (C) 1998, 1999, 2001-2004 Hewlett-Packard Co
   *	David Mosberger-Tang <davidm@hpl.hp.com>
   */
  
  #include <linux/compiler.h>
  #include <linux/errno.h>
  #include <linux/sched.h>
  #include <linux/page-flags.h>
  #include <linux/mm.h>
  
  #include <asm/intrinsics.h>
  #include <asm/pgtable.h>
  #include <asm/io.h>
  
  /*
   * For historical reasons, the following macros are grossly misnamed:
   */
  #define KERNEL_DS	((mm_segment_t) { ~0UL })		/* cf. access_ok() */
  #define USER_DS		((mm_segment_t) { TASK_SIZE-1 })	/* cf. access_ok() */
  
  #define VERIFY_READ	0
  #define VERIFY_WRITE	1
  
  #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)
  
  /*
   * When accessing user memory, we need to make sure the entire area really is in
   * user-level space.  In order to do this efficiently, we make sure that the page at
   * address TASK_SIZE is never valid.  We also need to make sure that the address doesn't
   * point inside the virtually mapped linear page table.
   */
  #define __access_ok(addr, size, segment)						\
  ({											\
  	__chk_user_ptr(addr);								\
  	(likely((unsigned long) (addr) <= (segment).seg)				\
  	 && ((segment).seg == KERNEL_DS.seg						\
  	     || likely(REGION_OFFSET((unsigned long) (addr)) < RGN_MAP_LIMIT)));	\
  })
  #define access_ok(type, addr, size)	__access_ok((addr), (size), get_fs())
  
  /*
   * These are the main single-value transfer routines.  They automatically
   * use the right size if we just have the right pointer type.
   *
   * Careful to not
   * (a) re-use the arguments for side effects (sizeof/typeof is ok)
   * (b) require any knowledge of processes at this stage
   */
  #define put_user(x, ptr)	__put_user_check((__typeof__(*(ptr))) (x), (ptr), sizeof(*(ptr)), get_fs())
  #define get_user(x, ptr)	__get_user_check((x), (ptr), sizeof(*(ptr)), get_fs())
  
  /*
   * The "__xxx" versions do not do address space checking, useful when
   * doing multiple accesses to the same area (the programmer has to do the
   * checks by hand with "access_ok()")
   */
  #define __put_user(x, ptr)	__put_user_nocheck((__typeof__(*(ptr))) (x), (ptr), sizeof(*(ptr)))
  #define __get_user(x, ptr)	__get_user_nocheck((x), (ptr), sizeof(*(ptr)))
  
  extern long __put_user_unaligned_unknown (void);
  
  #define __put_user_unaligned(x, ptr)								\
  ({												\
  	long __ret;										\
  	switch (sizeof(*(ptr))) {								\
  		case 1: __ret = __put_user((x), (ptr)); break;					\
  		case 2: __ret = (__put_user((x), (u8 __user *)(ptr)))				\
  			| (__put_user((x) >> 8, ((u8 __user *)(ptr) + 1))); break;		\
  		case 4: __ret = (__put_user((x), (u16 __user *)(ptr)))				\
  			| (__put_user((x) >> 16, ((u16 __user *)(ptr) + 1))); break;		\
  		case 8: __ret = (__put_user((x), (u32 __user *)(ptr)))				\
  			| (__put_user((x) >> 32, ((u32 __user *)(ptr) + 1))); break;		\
  		default: __ret = __put_user_unaligned_unknown();				\
  	}											\
  	__ret;											\
  })
  
  extern long __get_user_unaligned_unknown (void);
  
  #define __get_user_unaligned(x, ptr)								\
  ({												\
  	long __ret;										\
  	switch (sizeof(*(ptr))) {								\
  		case 1: __ret = __get_user((x), (ptr)); break;					\
  		case 2: __ret = (__get_user((x), (u8 __user *)(ptr)))				\
  			| (__get_user((x) >> 8, ((u8 __user *)(ptr) + 1))); break;		\
  		case 4: __ret = (__get_user((x), (u16 __user *)(ptr)))				\
  			| (__get_user((x) >> 16, ((u16 __user *)(ptr) + 1))); break;		\
  		case 8: __ret = (__get_user((x), (u32 __user *)(ptr)))				\
  			| (__get_user((x) >> 32, ((u32 __user *)(ptr) + 1))); break;		\
  		default: __ret = __get_user_unaligned_unknown();				\
  	}											\
  	__ret;											\
  })
  
  #ifdef ASM_SUPPORTED
    struct __large_struct { unsigned long buf[100]; };
  # define __m(x) (*(struct __large_struct __user *)(x))
  
  /* We need to declare the __ex_table section before we can use it in .xdata.  */
  asm (".section \"__ex_table\", \"a\"\n\t.previous");
  
  # define __get_user_size(val, addr, n, err)							\
  do {												\
  	register long __gu_r8 asm ("r8") = 0;							\
  	register long __gu_r9 asm ("r9");							\
  	asm ("\n[1:]\tld"#n" %0=%2%P2\t// %0 and %1 get overwritten by exception handler\n"	\
  	     "\t.xdata4 \"__ex_table\", 1b-., 1f-.+4\n"						\
  	     "[1:]"										\
  	     : "=r"(__gu_r9), "=r"(__gu_r8) : "m"(__m(addr)), "1"(__gu_r8));			\
  	(err) = __gu_r8;									\
  	(val) = __gu_r9;									\
  } while (0)
  
  /*
   * The "__put_user_size()" macro tells gcc it reads from memory instead of writing it.  This
   * is because they do not write to any memory gcc knows about, so there are no aliasing
   * issues.
   */
  # define __put_user_size(val, addr, n, err)							\
  do {												\
  	register long __pu_r8 asm ("r8") = 0;							\
  	asm volatile ("\n[1:]\tst"#n" %1=%r2%P1\t// %0 gets overwritten by exception handler\n"	\
  		      "\t.xdata4 \"__ex_table\", 1b-., 1f-.\n"					\
  		      "[1:]"									\
  		      : "=r"(__pu_r8) : "m"(__m(addr)), "rO"(val), "0"(__pu_r8));		\
  	(err) = __pu_r8;									\
  } while (0)
  
  #else /* !ASM_SUPPORTED */
  # define RELOC_TYPE	2	/* ip-rel */
  # define __get_user_size(val, addr, n, err)				\
  do {									\
  	__ld_user("__ex_table", (unsigned long) addr, n, RELOC_TYPE);	\
  	(err) = ia64_getreg(_IA64_REG_R8);				\
  	(val) = ia64_getreg(_IA64_REG_R9);				\
  } while (0)
  # define __put_user_size(val, addr, n, err)							\
  do {												\
  	__st_user("__ex_table", (unsigned long) addr, n, RELOC_TYPE, (unsigned long) (val));	\
  	(err) = ia64_getreg(_IA64_REG_R8);							\
  } while (0)
  #endif /* !ASM_SUPPORTED */
  
  extern void __get_user_unknown (void);
  
  /*
   * Evaluating arguments X, PTR, SIZE, and SEGMENT may involve subroutine-calls, which
   * could clobber r8 and r9 (among others).  Thus, be careful not to evaluate it while
   * using r8/r9.
   */
  #define __do_get_user(check, x, ptr, size, segment)					\
  ({											\
  	const __typeof__(*(ptr)) __user *__gu_ptr = (ptr);				\
  	__typeof__ (size) __gu_size = (size);						\
  	long __gu_err = -EFAULT;							\
  	unsigned long __gu_val = 0;							\
  	if (!check || __access_ok(__gu_ptr, size, segment))				\
  		switch (__gu_size) {							\
  		      case 1: __get_user_size(__gu_val, __gu_ptr, 1, __gu_err); break;	\
  		      case 2: __get_user_size(__gu_val, __gu_ptr, 2, __gu_err); break;	\
  		      case 4: __get_user_size(__gu_val, __gu_ptr, 4, __gu_err); break;	\
  		      case 8: __get_user_size(__gu_val, __gu_ptr, 8, __gu_err); break;	\
  		      default: __get_user_unknown(); break;				\
  		}									\
  	(x) = (__typeof__(*(__gu_ptr))) __gu_val;					\
  	__gu_err;									\
  })
  
  #define __get_user_nocheck(x, ptr, size)	__do_get_user(0, x, ptr, size, KERNEL_DS)
  #define __get_user_check(x, ptr, size, segment)	__do_get_user(1, x, ptr, size, segment)
  
  extern void __put_user_unknown (void);
  
  /*
   * Evaluating arguments X, PTR, SIZE, and SEGMENT may involve subroutine-calls, which
   * could clobber r8 (among others).  Thus, be careful not to evaluate them while using r8.
   */
  #define __do_put_user(check, x, ptr, size, segment)					\
  ({											\
  	__typeof__ (x) __pu_x = (x);							\
  	__typeof__ (*(ptr)) __user *__pu_ptr = (ptr);					\
  	__typeof__ (size) __pu_size = (size);						\
  	long __pu_err = -EFAULT;							\
  											\
  	if (!check || __access_ok(__pu_ptr, __pu_size, segment))			\
  		switch (__pu_size) {							\
  		      case 1: __put_user_size(__pu_x, __pu_ptr, 1, __pu_err); break;	\
  		      case 2: __put_user_size(__pu_x, __pu_ptr, 2, __pu_err); break;	\
  		      case 4: __put_user_size(__pu_x, __pu_ptr, 4, __pu_err); break;	\
  		      case 8: __put_user_size(__pu_x, __pu_ptr, 8, __pu_err); break;	\
  		      default: __put_user_unknown(); break;				\
  		}									\
  	__pu_err;									\
  })
  
  #define __put_user_nocheck(x, ptr, size)	__do_put_user(0, x, ptr, size, KERNEL_DS)
  #define __put_user_check(x, ptr, size, segment)	__do_put_user(1, x, ptr, size, segment)
  
  /*
   * Complex access routines
   */
  extern unsigned long __must_check __copy_user (void __user *to, const void __user *from,
  					       unsigned long count);
  
  static inline unsigned long
  __copy_to_user (void __user *to, const void *from, unsigned long count)
  {
  	return __copy_user(to, (__force void __user *) from, count);
  }
  
  static inline unsigned long
  __copy_from_user (void *to, const void __user *from, unsigned long count)
  {
  	return __copy_user((__force void __user *) to, from, count);
  }
  
  #define __copy_to_user_inatomic		__copy_to_user
  #define __copy_from_user_inatomic	__copy_from_user
  #define copy_to_user(to, from, n)							\
  ({											\
  	void __user *__cu_to = (to);							\
  	const void *__cu_from = (from);							\
  	long __cu_len = (n);								\
  											\
  	if (__access_ok(__cu_to, __cu_len, get_fs()))					\
  		__cu_len = __copy_user(__cu_to, (__force void __user *) __cu_from, __cu_len);	\
  	__cu_len;									\
  })
  
  #define copy_from_user(to, from, n)							\
  ({											\
  	void *__cu_to = (to);								\
  	const void __user *__cu_from = (from);						\
  	long __cu_len = (n);								\
  											\
  	__chk_user_ptr(__cu_from);							\
  	if (__access_ok(__cu_from, __cu_len, get_fs()))					\
  		__cu_len = __copy_user((__force void __user *) __cu_to, __cu_from, __cu_len);	\
  	__cu_len;									\
  })
  
  #define __copy_in_user(to, from, size)	__copy_user((to), (from), (size))
  
  static inline unsigned long
  copy_in_user (void __user *to, const void __user *from, unsigned long n)
  {
  	if (likely(access_ok(VERIFY_READ, from, n) && access_ok(VERIFY_WRITE, to, n)))
  		n = __copy_user(to, from, n);
  	return n;
  }
  
  extern unsigned long __do_clear_user (void __user *, unsigned long);
  
  #define __clear_user(to, n)		__do_clear_user(to, n)
  
  #define clear_user(to, n)					\
  ({								\
  	unsigned long __cu_len = (n);				\
  	if (__access_ok(to, __cu_len, get_fs()))		\
  		__cu_len = __do_clear_user(to, __cu_len);	\
  	__cu_len;						\
  })
  
  
  /*
   * Returns: -EFAULT if exception before terminator, N if the entire buffer filled, else
   * strlen.
   */
  extern long __must_check __strncpy_from_user (char *to, const char __user *from, long to_len);
  
  #define strncpy_from_user(to, from, n)					\
  ({									\
  	const char __user * __sfu_from = (from);			\
  	long __sfu_ret = -EFAULT;					\
  	if (__access_ok(__sfu_from, 0, get_fs()))			\
  		__sfu_ret = __strncpy_from_user((to), __sfu_from, (n));	\
  	__sfu_ret;							\
  })
  
  /* Returns: 0 if bad, string length+1 (memory size) of string if ok */
  extern unsigned long __strlen_user (const char __user *);
  
  #define strlen_user(str)				\
  ({							\
  	const char __user *__su_str = (str);		\
  	unsigned long __su_ret = 0;			\
  	if (__access_ok(__su_str, 0, get_fs()))		\
  		__su_ret = __strlen_user(__su_str);	\
  	__su_ret;					\
  })
  
  /*
   * Returns: 0 if exception before NUL or reaching the supplied limit
   * (N), a value greater than N if the limit would be exceeded, else
   * strlen.
   */
  extern unsigned long __strnlen_user (const char __user *, long);
  
  #define strnlen_user(str, len)					\
  ({								\
  	const char __user *__su_str = (str);			\
  	unsigned long __su_ret = 0;				\
  	if (__access_ok(__su_str, 0, get_fs()))			\
  		__su_ret = __strnlen_user(__su_str, len);	\
  	__su_ret;						\
  })
  
  /* Generic code can't deal with the location-relative format that we use for compactness.  */
  #define ARCH_HAS_SORT_EXTABLE
  #define ARCH_HAS_SEARCH_EXTABLE
  
  struct exception_table_entry {
  	int addr;	/* location-relative address of insn this fixup is for */
  	int cont;	/* location-relative continuation addr.; if bit 2 is set, r9 is set to 0 */
  };
  
  extern void ia64_handle_exception (struct pt_regs *regs, const struct exception_table_entry *e);
  extern const struct exception_table_entry *search_exception_tables (unsigned long addr);
  
  static inline int
  ia64_done_with_exception (struct pt_regs *regs)
  {
  	const struct exception_table_entry *e;
  	e = search_exception_tables(regs->cr_iip + ia64_psr(regs)->ri);
  	if (e) {
  		ia64_handle_exception(regs, e);
  		return 1;
  	}
  	return 0;
  }
  
  #define ARCH_HAS_TRANSLATE_MEM_PTR	1
  static __inline__ char *
  xlate_dev_mem_ptr (unsigned long p)
  {
  	struct page *page;
  	char * ptr;
  
  	page = pfn_to_page(p >> PAGE_SHIFT);
  	if (PageUncached(page))
  		ptr = (char *)p + __IA64_UNCACHED_OFFSET;
  	else
  		ptr = __va(p);
  
  	return ptr;
  }
  
  /*
   * Convert a virtual cached kernel memory pointer to an uncached pointer
   */
  static __inline__ char *
  xlate_dev_kmem_ptr (char * p)
  {
  	struct page *page;
  	char * ptr;
  
  	page = virt_to_page((unsigned long)p);
  	if (PageUncached(page))
  		ptr = (char *)__pa(p) + __IA64_UNCACHED_OFFSET;
  	else
  		ptr = p;
  
  	return ptr;
  }
  
  #endif /* _ASM_IA64_UACCESS_H */
  