text: /*
   *  arch/arm/include/asm/uaccess.h
   *
   * This program is free software; you can redistribute it and/or modify
   * it under the terms of the GNU General Public License version 2 as
   * published by the Free Software Foundation.
   */
  #ifndef _ASMARM_UACCESS_H
  #define _ASMARM_UACCESS_H
  
  /*
   * User space memory access functions
   */
  #include <linux/string.h>
  #include <linux/thread_info.h>
  #include <asm/errno.h>
  #include <asm/memory.h>
  #include <asm/domain.h>
  #include <asm/unified.h>
  #include <asm/compiler.h>
  
  #ifndef CONFIG_HAVE_EFFICIENT_UNALIGNED_ACCESS
  #include <asm-generic/uaccess-unaligned.h>
  #else
  #define __get_user_unaligned __get_user
  #define __put_user_unaligned __put_user
  #endif
  
  #define VERIFY_READ 0
  #define VERIFY_WRITE 1
  
  /*
   * 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 two functions allow hooking accesses to userspace to increase
   * system integrity by ensuring that the kernel can not inadvertantly
   * perform such accesses (eg, via list poison values) which could then
   * be exploited for priviledge escalation.
   */
  static inline unsigned int uaccess_save_and_enable(void)
  {
  #ifdef CONFIG_CPU_SW_DOMAIN_PAN
  	unsigned int old_domain = get_domain();
  
  	/* Set the current domain access to permit user accesses */
  	set_domain((old_domain & ~domain_mask(DOMAIN_USER)) |
  		   domain_val(DOMAIN_USER, DOMAIN_CLIENT));
  
  	return old_domain;
  #else
  	return 0;
  #endif
  }
  
  static inline void uaccess_restore(unsigned int flags)
  {
  #ifdef CONFIG_CPU_SW_DOMAIN_PAN
  	/* Restore the user access mask */
  	set_domain(flags);
  #endif
  }
  
  /*
   * These two are intentionally not defined anywhere - if the kernel
   * code generates any references to them, that's a bug.
   */
  extern int __get_user_bad(void);
  extern int __put_user_bad(void);
  
  /*
   * Note that this is actually 0x1,0000,0000
   */
  #define KERNEL_DS	0x00000000
  #define get_ds()	(KERNEL_DS)
  
  #ifdef CONFIG_MMU
  
  #define USER_DS		TASK_SIZE
  #define get_fs()	(current_thread_info()->addr_limit)
  
  static inline void set_fs(mm_segment_t fs)
  {
  	current_thread_info()->addr_limit = fs;
  	modify_domain(DOMAIN_KERNEL, fs ? DOMAIN_CLIENT : DOMAIN_MANAGER);
  }
  
  #define segment_eq(a, b)	((a) == (b))
  
  /* We use 33-bit arithmetic here... */
  #define __range_ok(addr, size) ({ \
  	unsigned long flag, roksum; \
  	__chk_user_ptr(addr);	\
  	__asm__("adds %1, %2, %3; sbcccs %1, %1, %0; movcc %0, #0" \
  		: "=&r" (flag), "=&r" (roksum) \
  		: "r" (addr), "Ir" (size), "0" (current_thread_info()->addr_limit) \
  		: "cc"); \
  	flag; })
  
  /*
   * Single-value transfer routines.  They automatically use the right
   * size if we just have the right pointer type.  Note that the functions
   * which read from user space (*get_*) need to take care not to leak
   * kernel data even if the calling code is buggy and fails to check
   * the return value.  This means zeroing out the destination variable
   * or buffer on error.  Normally this is done out of line by the
   * fixup code, but there are a few places where it intrudes on the
   * main code path.  When we only write to user space, there is no
   * problem.
   */
  extern int __get_user_1(void *);
  extern int __get_user_2(void *);
  extern int __get_user_4(void *);
  extern int __get_user_32t_8(void *);
  extern int __get_user_8(void *);
  extern int __get_user_64t_1(void *);
  extern int __get_user_64t_2(void *);
  extern int __get_user_64t_4(void *);
  
  #define __GUP_CLOBBER_1	"lr", "cc"
  #ifdef CONFIG_CPU_USE_DOMAINS
  #define __GUP_CLOBBER_2	"ip", "lr", "cc"
  #else
  #define __GUP_CLOBBER_2 "lr", "cc"
  #endif
  #define __GUP_CLOBBER_4	"lr", "cc"
  #define __GUP_CLOBBER_32t_8 "lr", "cc"
  #define __GUP_CLOBBER_8	"lr", "cc"
  
  #define __get_user_x(__r2, __p, __e, __l, __s)				\
  	   __asm__ __volatile__ (					\
  		__asmeq("%0", "r0") __asmeq("%1", "r2")			\
  		__asmeq("%3", "r1")					\
  		"bl	__get_user_" #__s				\
  		: "=&r" (__e), "=r" (__r2)				\
  		: "0" (__p), "r" (__l)					\
  		: __GUP_CLOBBER_##__s)
  
  /* narrowing a double-word get into a single 32bit word register: */
  #ifdef __ARMEB__
  #define __get_user_x_32t(__r2, __p, __e, __l, __s)			\
  	__get_user_x(__r2, __p, __e, __l, 32t_8)
  #else
  #define __get_user_x_32t __get_user_x
  #endif
  
  /*
   * storing result into proper least significant word of 64bit target var,
   * different only for big endian case where 64 bit __r2 lsw is r3:
   */
  #ifdef __ARMEB__
  #define __get_user_x_64t(__r2, __p, __e, __l, __s)		        \
  	   __asm__ __volatile__ (					\
  		__asmeq("%0", "r0") __asmeq("%1", "r2")			\
  		__asmeq("%3", "r1")					\
  		"bl	__get_user_64t_" #__s				\
  		: "=&r" (__e), "=r" (__r2)				\
  		: "0" (__p), "r" (__l)					\
  		: __GUP_CLOBBER_##__s)
  #else
  #define __get_user_x_64t __get_user_x
  #endif
  
  
  #define __get_user_check(x, p)						\
  	({								\
  		unsigned long __limit = current_thread_info()->addr_limit - 1; \
  		register const typeof(*(p)) __user *__p asm("r0") = (p);\
  		register typeof(x) __r2 asm("r2");			\
  		register unsigned long __l asm("r1") = __limit;		\
  		register int __e asm("r0");				\
  		unsigned int __ua_flags = uaccess_save_and_enable();	\
  		switch (sizeof(*(__p))) {				\
  		case 1:							\
  			if (sizeof((x)) >= 8)				\
  				__get_user_x_64t(__r2, __p, __e, __l, 1); \
  			else						\
  				__get_user_x(__r2, __p, __e, __l, 1);	\
  			break;						\
  		case 2:							\
  			if (sizeof((x)) >= 8)				\
  				__get_user_x_64t(__r2, __p, __e, __l, 2); \
  			else						\
  				__get_user_x(__r2, __p, __e, __l, 2);	\
  			break;						\
  		case 4:							\
  			if (sizeof((x)) >= 8)				\
  				__get_user_x_64t(__r2, __p, __e, __l, 4); \
  			else						\
  				__get_user_x(__r2, __p, __e, __l, 4);	\
  			break;						\
  		case 8:							\
  			if (sizeof((x)) < 8)				\
  				__get_user_x_32t(__r2, __p, __e, __l, 4); \
  			else						\
  				__get_user_x(__r2, __p, __e, __l, 8);	\
  			break;						\
  		default: __e = __get_user_bad(); break;			\
  		}							\
  		uaccess_restore(__ua_flags);				\
  		x = (typeof(*(p))) __r2;				\
  		__e;							\
  	})
  
  #define get_user(x, p)							\
  	({								\
  		might_fault();						\
  		__get_user_check(x, p);					\
  	 })
  
  extern int __put_user_1(void *, unsigned int);
  extern int __put_user_2(void *, unsigned int);
  extern int __put_user_4(void *, unsigned int);
  extern int __put_user_8(void *, unsigned long long);
  
  #define __put_user_check(__pu_val, __ptr, __err, __s)			\
  	({								\
  		unsigned long __limit = current_thread_info()->addr_limit - 1; \
  		register typeof(__pu_val) __r2 asm("r2") = __pu_val;	\
  		register const void __user *__p asm("r0") = __ptr;	\
  		register unsigned long __l asm("r1") = __limit;		\
  		register int __e asm("r0");				\
  		__asm__ __volatile__ (					\
  			__asmeq("%0", "r0") __asmeq("%2", "r2")		\
  			__asmeq("%3", "r1")				\
  			"bl	__put_user_" #__s			\
  			: "=&r" (__e)					\
  			: "0" (__p), "r" (__r2), "r" (__l)		\
  			: "ip", "lr", "cc");				\
  		__err = __e;						\
  	})
  
  #else /* CONFIG_MMU */
  
  /*
   * uClinux has only one addr space, so has simplified address limits.
   */
  #define USER_DS			KERNEL_DS
  
  #define segment_eq(a, b)		(1)
  #define __addr_ok(addr)		((void)(addr), 1)
  #define __range_ok(addr, size)	((void)(addr), 0)
  #define get_fs()		(KERNEL_DS)
  
  static inline void set_fs(mm_segment_t fs)
  {
  }
  
  #define get_user(x, p)	__get_user(x, p)
  #define __put_user_check __put_user_nocheck
  
  #endif /* CONFIG_MMU */
  
  #define access_ok(type, addr, size)	(__range_ok(addr, size) == 0)
  
  #define user_addr_max() \
  	(segment_eq(get_fs(), KERNEL_DS) ? ~0UL : get_fs())
  
  /*
   * The "__xxx" versions of the user access functions do not verify the
   * address space - it must have been done previously with a separate
   * "access_ok()" call.
   *
   * The "xxx_error" versions set the third argument to EFAULT if an
   * error occurs, and leave it unchanged on success.  Note that these
   * versions are void (ie, don't return a value as such).
   */
  #define __get_user(x, ptr)						\
  ({									\
  	long __gu_err = 0;						\
  	__get_user_err((x), (ptr), __gu_err);				\
  	__gu_err;							\
  })
  
  #define __get_user_error(x, ptr, err)					\
  ({									\
  	__get_user_err((x), (ptr), err);				\
  	(void) 0;							\
  })
  
  #define __get_user_err(x, ptr, err)					\
  do {									\
  	unsigned long __gu_addr = (unsigned long)(ptr);			\
  	unsigned long __gu_val;						\
  	unsigned int __ua_flags;					\
  	__chk_user_ptr(ptr);						\
  	might_fault();							\
  	__ua_flags = uaccess_save_and_enable();				\
  	switch (sizeof(*(ptr))) {					\
  	case 1:	__get_user_asm_byte(__gu_val, __gu_addr, err);	break;	\
  	case 2:	__get_user_asm_half(__gu_val, __gu_addr, err);	break;	\
  	case 4:	__get_user_asm_word(__gu_val, __gu_addr, err);	break;	\
  	default: (__gu_val) = __get_user_bad();				\
  	}								\
  	uaccess_restore(__ua_flags);					\
  	(x) = (__typeof__(*(ptr)))__gu_val;				\
  } while (0)
  
  #define __get_user_asm(x, addr, err, instr)			\
  	__asm__ __volatile__(					\
  	"1:	" TUSER(instr) " %1, [%2], #0\n"		\
  	"2:\n"							\
  	"	.pushsection .text.fixup,\"ax\"\n"		\
  	"	.align	2\n"					\
  	"3:	mov	%0, %3\n"				\
  	"	mov	%1, #0\n"				\
  	"	b	2b\n"					\
  	"	.popsection\n"					\
  	"	.pushsection __ex_table,\"a\"\n"		\
  	"	.align	3\n"					\
  	"	.long	1b, 3b\n"				\
  	"	.popsection"					\
  	: "+r" (err), "=&r" (x)					\
  	: "r" (addr), "i" (-EFAULT)				\
  	: "cc")
  
  #define __get_user_asm_byte(x, addr, err)			\
  	__get_user_asm(x, addr, err, ldrb)
  
  #ifndef __ARMEB__
  #define __get_user_asm_half(x, __gu_addr, err)			\
  ({								\
  	unsigned long __b1, __b2;				\
  	__get_user_asm_byte(__b1, __gu_addr, err);		\
  	__get_user_asm_byte(__b2, __gu_addr + 1, err);		\
  	(x) = __b1 | (__b2 << 8);				\
  })
  #else
  #define __get_user_asm_half(x, __gu_addr, err)			\
  ({								\
  	unsigned long __b1, __b2;				\
  	__get_user_asm_byte(__b1, __gu_addr, err);		\
  	__get_user_asm_byte(__b2, __gu_addr + 1, err);		\
  	(x) = (__b1 << 8) | __b2;				\
  })
  #endif
  
  #define __get_user_asm_word(x, addr, err)			\
  	__get_user_asm(x, addr, err, ldr)
  
  
  #define __put_user_switch(x, ptr, __err, __fn)				\
  	do {								\
  		const __typeof__(*(ptr)) __user *__pu_ptr = (ptr);	\
  		__typeof__(*(ptr)) __pu_val = (x);			\
  		unsigned int __ua_flags;				\
  		might_fault();						\
  		__ua_flags = uaccess_save_and_enable();			\
  		switch (sizeof(*(ptr))) {				\
  		case 1: __fn(__pu_val, __pu_ptr, __err, 1); break;	\
  		case 2:	__fn(__pu_val, __pu_ptr, __err, 2); break;	\
  		case 4:	__fn(__pu_val, __pu_ptr, __err, 4); break;	\
  		case 8:	__fn(__pu_val, __pu_ptr, __err, 8); break;	\
  		default: __err = __put_user_bad(); break;		\
  		}							\
  		uaccess_restore(__ua_flags);				\
  	} while (0)
  
  #define put_user(x, ptr)						\
  ({									\
  	int __pu_err = 0;						\
  	__put_user_switch((x), (ptr), __pu_err, __put_user_check);	\
  	__pu_err;							\
  })
  
  #define __put_user(x, ptr)						\
  ({									\
  	long __pu_err = 0;						\
  	__put_user_switch((x), (ptr), __pu_err, __put_user_nocheck);	\
  	__pu_err;							\
  })
  
  #define __put_user_error(x, ptr, err)					\
  ({									\
  	__put_user_switch((x), (ptr), (err), __put_user_nocheck);	\
  	(void) 0;							\
  })
  
  #define __put_user_nocheck(x, __pu_ptr, __err, __size)			\
  	do {								\
  		unsigned long __pu_addr = (unsigned long)__pu_ptr;	\
  		__put_user_nocheck_##__size(x, __pu_addr, __err);	\
  	} while (0)
  
  #define __put_user_nocheck_1 __put_user_asm_byte
  #define __put_user_nocheck_2 __put_user_asm_half
  #define __put_user_nocheck_4 __put_user_asm_word
  #define __put_user_nocheck_8 __put_user_asm_dword
  
  #define __put_user_asm(x, __pu_addr, err, instr)		\
  	__asm__ __volatile__(					\
  	"1:	" TUSER(instr) " %1, [%2], #0\n"		\
  	"2:\n"							\
  	"	.pushsection .text.fixup,\"ax\"\n"		\
  	"	.align	2\n"					\
  	"3:	mov	%0, %3\n"				\
  	"	b	2b\n"					\
  	"	.popsection\n"					\
  	"	.pushsection __ex_table,\"a\"\n"		\
  	"	.align	3\n"					\
  	"	.long	1b, 3b\n"				\
  	"	.popsection"					\
  	: "+r" (err)						\
  	: "r" (x), "r" (__pu_addr), "i" (-EFAULT)		\
  	: "cc")
  
  #define __put_user_asm_byte(x, __pu_addr, err)			\
  	__put_user_asm(x, __pu_addr, err, strb)
  
  #ifndef __ARMEB__
  #define __put_user_asm_half(x, __pu_addr, err)			\
  ({								\
  	unsigned long __temp = (__force unsigned long)(x);	\
  	__put_user_asm_byte(__temp, __pu_addr, err);		\
  	__put_user_asm_byte(__temp >> 8, __pu_addr + 1, err);	\
  })
  #else
  #define __put_user_asm_half(x, __pu_addr, err)			\
  ({								\
  	unsigned long __temp = (__force unsigned long)(x);	\
  	__put_user_asm_byte(__temp >> 8, __pu_addr, err);	\
  	__put_user_asm_byte(__temp, __pu_addr + 1, err);	\
  })
  #endif
  
  #define __put_user_asm_word(x, __pu_addr, err)			\
  	__put_user_asm(x, __pu_addr, err, str)
  
  #ifndef __ARMEB__
  #define	__reg_oper0	"%R2"
  #define	__reg_oper1	"%Q2"
  #else
  #define	__reg_oper0	"%Q2"
  #define	__reg_oper1	"%R2"
  #endif
  
  #define __put_user_asm_dword(x, __pu_addr, err)			\
  	__asm__ __volatile__(					\
   ARM(	"1:	" TUSER(str) "	" __reg_oper1 ", [%1], #4\n"	) \
   ARM(	"2:	" TUSER(str) "	" __reg_oper0 ", [%1]\n"	) \
   THUMB(	"1:	" TUSER(str) "	" __reg_oper1 ", [%1]\n"	) \
   THUMB(	"2:	" TUSER(str) "	" __reg_oper0 ", [%1, #4]\n"	) \
  	"3:\n"							\
  	"	.pushsection .text.fixup,\"ax\"\n"		\
  	"	.align	2\n"					\
  	"4:	mov	%0, %3\n"				\
  	"	b	3b\n"					\
  	"	.popsection\n"					\
  	"	.pushsection __ex_table,\"a\"\n"		\
  	"	.align	3\n"					\
  	"	.long	1b, 4b\n"				\
  	"	.long	2b, 4b\n"				\
  	"	.popsection"					\
  	: "+r" (err), "+r" (__pu_addr)				\
  	: "r" (x), "i" (-EFAULT)				\
  	: "cc")
  
  
  #ifdef CONFIG_MMU
  extern unsigned long __must_check
  arm_copy_from_user(void *to, const void __user *from, unsigned long n);
  
  static inline unsigned long __must_check
  __arch_copy_from_user(void *to, const void __user *from, unsigned long n)
  {
  	unsigned int __ua_flags;
  
  	__ua_flags = uaccess_save_and_enable();
  	n = arm_copy_from_user(to, from, n);
  	uaccess_restore(__ua_flags);
  	return n;
  }
  
  extern unsigned long __must_check
  arm_copy_to_user(void __user *to, const void *from, unsigned long n);
  extern unsigned long __must_check
  __copy_to_user_std(void __user *to, const void *from, unsigned long n);
  
  static inline unsigned long __must_check
  __arch_copy_to_user(void __user *to, const void *from, unsigned long n)
  {
  #ifndef CONFIG_UACCESS_WITH_MEMCPY
  	unsigned int __ua_flags;
  	__ua_flags = uaccess_save_and_enable();
  	n = arm_copy_to_user(to, from, n);
  	uaccess_restore(__ua_flags);
  	return n;
  #else
  	return arm_copy_to_user(to, from, n);
  #endif
  }
  
  extern unsigned long __must_check
  arm_clear_user(void __user *addr, unsigned long n);
  extern unsigned long __must_check
  __clear_user_std(void __user *addr, unsigned long n);
  
  static inline unsigned long __must_check
  __clear_user(void __user *addr, unsigned long n)
  {
  	unsigned int __ua_flags = uaccess_save_and_enable();
  	n = arm_clear_user(addr, n);
  	uaccess_restore(__ua_flags);
  	return n;
  }
  
  #else
  #define __arch_copy_from_user(to, from, n)	\
  					(memcpy(to, (void __force *)from, n), 0)
  #define __arch_copy_to_user(to, from, n)	\
  					(memcpy((void __force *)to, from, n), 0)
  #define __clear_user(addr, n)		(memset((void __force *)addr, 0, n), 0)
  #endif
  
  static inline unsigned long __must_check
  __copy_from_user(void *to, const void __user *from, unsigned long n)
  {
  	check_object_size(to, n, false);
  	return __arch_copy_from_user(to, from, n);
  }
  
  static inline unsigned long __must_check
  copy_from_user(void *to, const void __user *from, unsigned long n)
  {
  	unsigned long res = n;
  
  	check_object_size(to, n, false);
  
  	if (likely(access_ok(VERIFY_READ, from, n)))
  		res = __arch_copy_from_user(to, from, n);
  	if (unlikely(res))
  		memset(to + (n - res), 0, res);
  	return res;
  }
  
  static inline unsigned long __must_check
  __copy_to_user(void __user *to, const void *from, unsigned long n)
  {
  	check_object_size(from, n, true);
  
  	return __arch_copy_to_user(to, from, n);
  }
  
  static inline unsigned long __must_check
  copy_to_user(void __user *to, const void *from, unsigned long n)
  {
  	check_object_size(from, n, true);
  
  	if (access_ok(VERIFY_WRITE, to, n))
  		n = __arch_copy_to_user(to, from, n);
  	return n;
  }
  
  #define __copy_to_user_inatomic __copy_to_user
  #define __copy_from_user_inatomic __copy_from_user
  
  static inline unsigned long __must_check clear_user(void __user *to, unsigned long n)
  {
  	if (access_ok(VERIFY_WRITE, to, n))
  		n = __clear_user(to, n);
  	return n;
  }
  
  /* These are from lib/ code, and use __get_user() and friends */
  extern long strncpy_from_user(char *dest, const char __user *src, long count);
  
  extern __must_check long strlen_user(const char __user *str);
  extern __must_check long strnlen_user(const char __user *str, long n);
  
  #endif /* _ASMARM_UACCESS_H */
  