text: /* $Id: uaccess.h,v 1.35 2002/02/09 19:49:31 davem Exp $ */
  #ifndef _ASM_UACCESS_H
  #define _ASM_UACCESS_H
  
  /*
   * User space memory access functions
   */
  
  #ifdef __KERNEL__
  #include <linux/compiler.h>
  #include <linux/sched.h>
  #include <linux/string.h>
  #include <asm/a.out.h>
  #include <asm/asi.h>
  #include <asm/system.h>
  #include <asm/spitfire.h>
  #endif
  
  #ifndef __ASSEMBLY__
  
  /*
   * Sparc64 is segmented, though more like the M68K than the I386. 
   * We use the secondary ASI to address user memory, which references a
   * completely different VM map, thus there is zero chance of the user
   * doing something queer and tricking us into poking kernel memory.
   *
   * What is left here is basically what is needed for the other parts of
   * the kernel that expect to be able to manipulate, erum, "segments".
   * Or perhaps more properly, permissions.
   *
   * "For historical reasons, these macros are grossly misnamed." -Linus
   */
  
  #define KERNEL_DS   ((mm_segment_t) { ASI_P })
  #define USER_DS     ((mm_segment_t) { ASI_AIUS })	/* har har har */
  
  #define VERIFY_READ	0
  #define VERIFY_WRITE	1
  
  #define get_fs() ((mm_segment_t) { get_thread_current_ds() })
  #define get_ds() (KERNEL_DS)
  
  #define segment_eq(a,b)  ((a).seg == (b).seg)
  
  #define set_fs(val)								\
  do {										\
  	set_thread_current_ds((val).seg);					\
  	__asm__ __volatile__ ("wr %%g0, %0, %%asi" : : "r" ((val).seg));	\
  } while(0)
  
  #define __user_ok(addr,size) 1
  #define __kernel_ok (segment_eq(get_fs(), KERNEL_DS))
  #define __access_ok(addr,size) 1
  #define access_ok(type,addr,size) 1
  
  static inline int verify_area(int type, const void __user * addr, unsigned long size)
  {
  	return 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.
   *
   * There is a special way how to put a range of potentially faulting
   * insns (like twenty ldd/std's with now intervening other instructions)
   * You specify address of first in insn and 0 in fixup and in the next
   * exception_table_entry you specify last potentially faulting insn + 1
   * and in fixup the routine which should handle the fault.
   * That fixup code will get
   * (faulting_insn_address - first_insn_in_the_range_address)/4
   * in %g2 (ie. index of the faulting instruction in the range).
   */
  
  struct exception_table_entry
  {
          unsigned insn, fixup;
  };
  
  /* Special exable search, which handles ranges.  Returns fixup */
  unsigned long search_extables_range(unsigned long addr, unsigned long *g2);
  
  extern void __ret_efault(void);
  
  /* Uh, these should become 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.
   */
  #define put_user(x,ptr) ({ \
  unsigned long __pu_addr = (unsigned long)(ptr); \
  __put_user_nocheck((__typeof__(*(ptr)))(x),__pu_addr,sizeof(*(ptr))); })
  
  #define get_user(x,ptr) ({ \
  unsigned long __gu_addr = (unsigned long)(ptr); \
  __get_user_nocheck((x),__gu_addr,sizeof(*(ptr)),__typeof__(*(ptr))); })
  
  #define __put_user(x,ptr) put_user(x,ptr)
  #define __get_user(x,ptr) get_user(x,ptr)
  
  struct __large_struct { unsigned long buf[100]; };
  #define __m(x) ((struct __large_struct *)(x))
  
  #define __put_user_nocheck(data,addr,size) ({ \
  register int __pu_ret; \
  switch (size) { \
  case 1: __put_user_asm(data,b,addr,__pu_ret); break; \
  case 2: __put_user_asm(data,h,addr,__pu_ret); break; \
  case 4: __put_user_asm(data,w,addr,__pu_ret); break; \
  case 8: __put_user_asm(data,x,addr,__pu_ret); break; \
  default: __pu_ret = __put_user_bad(); break; \
  } __pu_ret; })
  
  #define __put_user_nocheck_ret(data,addr,size,retval) ({ \
  register int __foo __asm__ ("l1"); \
  switch (size) { \
  case 1: __put_user_asm_ret(data,b,addr,retval,__foo); break; \
  case 2: __put_user_asm_ret(data,h,addr,retval,__foo); break; \
  case 4: __put_user_asm_ret(data,w,addr,retval,__foo); break; \
  case 8: __put_user_asm_ret(data,x,addr,retval,__foo); break; \
  default: if (__put_user_bad()) return retval; break; \
  } })
  
  #define __put_user_asm(x,size,addr,ret)					\
  __asm__ __volatile__(							\
  	"/* Put user asm, inline. */\n"					\
  "1:\t"	"st"#size "a %1, [%2] %%asi\n\t"				\
  	"clr	%0\n"							\
  "2:\n\n\t"								\
  	".section .fixup,#alloc,#execinstr\n\t"				\
  	".align	4\n"							\
  "3:\n\t"								\
  	"b	2b\n\t"							\
  	" mov	%3, %0\n\n\t"						\
  	".previous\n\t"							\
  	".section __ex_table,#alloc\n\t"				\
  	".align	4\n\t"							\
  	".word	1b, 3b\n\t"						\
  	".previous\n\n\t"						\
         : "=r" (ret) : "r" (x), "r" (__m(addr)),				\
  	 "i" (-EFAULT))
  
  #define __put_user_asm_ret(x,size,addr,ret,foo)				\
  if (__builtin_constant_p(ret) && ret == -EFAULT)			\
  __asm__ __volatile__(							\
  	"/* Put user asm ret, inline. */\n"				\
  "1:\t"	"st"#size "a %1, [%2] %%asi\n\n\t"				\
  	".section __ex_table,#alloc\n\t"				\
  	".align	4\n\t"							\
  	".word	1b, __ret_efault\n\n\t"					\
  	".previous\n\n\t"						\
         : "=r" (foo) : "r" (x), "r" (__m(addr)));			\
  else									\
  __asm__ __volatile(							\
  	"/* Put user asm ret, inline. */\n"				\
  "1:\t"	"st"#size "a %1, [%2] %%asi\n\n\t"				\
  	".section .fixup,#alloc,#execinstr\n\t"				\
  	".align	4\n"							\
  "3:\n\t"								\
  	"ret\n\t"							\
  	" restore %%g0, %3, %%o0\n\n\t"					\
  	".previous\n\t"							\
  	".section __ex_table,#alloc\n\t"				\
  	".align	4\n\t"							\
  	".word	1b, 3b\n\n\t"						\
  	".previous\n\n\t"						\
         : "=r" (foo) : "r" (x), "r" (__m(addr)),				\
           "i" (ret))
  
  extern int __put_user_bad(void);
  
  #define __get_user_nocheck(data,addr,size,type) ({ \
  register int __gu_ret; \
  register unsigned long __gu_val; \
  switch (size) { \
  case 1: __get_user_asm(__gu_val,ub,addr,__gu_ret); break; \
  case 2: __get_user_asm(__gu_val,uh,addr,__gu_ret); break; \
  case 4: __get_user_asm(__gu_val,uw,addr,__gu_ret); break; \
  case 8: __get_user_asm(__gu_val,x,addr,__gu_ret); break; \
  default: __gu_val = 0; __gu_ret = __get_user_bad(); break; \
  } data = (type) __gu_val; __gu_ret; })
  
  #define __get_user_nocheck_ret(data,addr,size,type,retval) ({ \
  register unsigned long __gu_val __asm__ ("l1"); \
  switch (size) { \
  case 1: __get_user_asm_ret(__gu_val,ub,addr,retval); break; \
  case 2: __get_user_asm_ret(__gu_val,uh,addr,retval); break; \
  case 4: __get_user_asm_ret(__gu_val,uw,addr,retval); break; \
  case 8: __get_user_asm_ret(__gu_val,x,addr,retval); break; \
  default: if (__get_user_bad()) return retval; \
  } data = (type) __gu_val; })
  
  #define __get_user_asm(x,size,addr,ret)					\
  __asm__ __volatile__(							\
  	"/* Get user asm, inline. */\n"					\
  "1:\t"	"ld"#size "a [%2] %%asi, %1\n\t"				\
  	"clr	%0\n"							\
  "2:\n\n\t"								\
  	".section .fixup,#alloc,#execinstr\n\t"				\
  	".align	4\n"							\
  "3:\n\t"								\
  	"clr	%1\n\t"							\
  	"b	2b\n\t"							\
  	" mov	%3, %0\n\n\t"						\
  	".previous\n\t"							\
  	".section __ex_table,#alloc\n\t"				\
  	".align	4\n\t"							\
  	".word	1b, 3b\n\n\t"						\
  	".previous\n\t"							\
         : "=r" (ret), "=r" (x) : "r" (__m(addr)),			\
  	 "i" (-EFAULT))
  
  #define __get_user_asm_ret(x,size,addr,retval)				\
  if (__builtin_constant_p(retval) && retval == -EFAULT)			\
  __asm__ __volatile__(							\
  	"/* Get user asm ret, inline. */\n"				\
  "1:\t"	"ld"#size "a [%1] %%asi, %0\n\n\t"				\
  	".section __ex_table,#alloc\n\t"				\
  	".align	4\n\t"							\
  	".word	1b,__ret_efault\n\n\t"					\
  	".previous\n\t"							\
         : "=r" (x) : "r" (__m(addr)));					\
  else									\
  __asm__ __volatile__(							\
  	"/* Get user asm ret, inline. */\n"				\
  "1:\t"	"ld"#size "a [%1] %%asi, %0\n\n\t"				\
  	".section .fixup,#alloc,#execinstr\n\t"				\
  	".align	4\n"							\
  "3:\n\t"								\
  	"ret\n\t"							\
  	" restore %%g0, %2, %%o0\n\n\t"					\
  	".previous\n\t"							\
  	".section __ex_table,#alloc\n\t"				\
  	".align	4\n\t"							\
  	".word	1b, 3b\n\n\t"						\
  	".previous\n\t"							\
         : "=r" (x) : "r" (__m(addr)), "i" (retval))
  
  extern int __get_user_bad(void);
  
  extern unsigned long __copy_from_user(void *to, const void __user *from,
  				      unsigned long size);
  
  extern unsigned long __copy_to_user(void __user *to, const void *from,
  				    unsigned long size);
  
  extern unsigned long __copy_in_user(void __user *to, const void __user *from,
  				    unsigned long size);
  
  #define copy_from_user __copy_from_user
  #define copy_to_user __copy_to_user
  #define copy_in_user __copy_in_user
  
  extern unsigned long __bzero_noasi(void *, unsigned long);
  
  static inline unsigned long __clear_user(void __user *addr, unsigned long size)
  {
  	
  	return __bzero_noasi((void *) addr, size);
  }
  
  #define clear_user __clear_user
  
  extern long __strncpy_from_user(char *dest, const char __user *src, long count);
  
  #define strncpy_from_user __strncpy_from_user
  
  extern long __strlen_user(const char __user *);
  extern long __strnlen_user(const char __user *, long len);
  
  #define strlen_user __strlen_user
  #define strnlen_user __strnlen_user
  
  #endif  /* __ASSEMBLY__ */
  
  #endif /* _ASM_UACCESS_H */
  