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uaccess.h

/*
 *  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/system.h>
#include <asm/unified.h>

#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 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))

#define __addr_ok(addr) ({ \
      unsigned long flag; \
      __asm__("cmp %2, %0; movlo %0, #0" \
            : "=&r" (flag) \
            : "0" (current_thread_info()->addr_limit), "r" (addr) \
            : "cc"); \
      (flag == 0); })

/* 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 *);

#define __get_user_x(__r2,__p,__e,__s,__i...)                     \
         __asm__ __volatile__ (                             \
            __asmeq("%0", "r0") __asmeq("%1", "r2")               \
            "bl   __get_user_" #__s                   \
            : "=&r" (__e), "=r" (__r2)                      \
            : "0" (__p)                               \
            : __i, "cc")

#define get_user(x,p)                                       \
      ({                                              \
            register const typeof(*(p)) __user *__p asm("r0") = (p);\
            register unsigned long __r2 asm("r2");                \
            register int __e asm("r0");                     \
            switch (sizeof(*(__p))) {                       \
            case 1:                                         \
                  __get_user_x(__r2, __p, __e, 1, "lr");          \
                        break;                                    \
            case 2:                                         \
                  __get_user_x(__r2, __p, __e, 2, "r3", "lr");    \
                  break;                                    \
            case 4:                                         \
                        __get_user_x(__r2, __p, __e, 4, "lr");          \
                  break;                                    \
            default: __e = __get_user_bad(); break;               \
            }                                         \
            x = (typeof(*(p))) __r2;                        \
            __e;                                      \
      })

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_x(__r2,__p,__e,__s)                            \
         __asm__ __volatile__ (                             \
            __asmeq("%0", "r0") __asmeq("%2", "r2")               \
            "bl   __put_user_" #__s                   \
            : "=&r" (__e)                                   \
            : "0" (__p), "r" (__r2)                         \
            : "ip", "lr", "cc")

#define put_user(x,p)                                       \
      ({                                              \
            register const typeof(*(p)) __r2 asm("r2") = (x);     \
            register const typeof(*(p)) __user *__p asm("r0") = (p);\
            register int __e asm("r0");                     \
            switch (sizeof(*(__p))) {                       \
            case 1:                                         \
                  __put_user_x(__r2, __p, __e, 1);          \
                  break;                                    \
            case 2:                                         \
                  __put_user_x(__r2, __p, __e, 2);          \
                  break;                                    \
            case 4:                                         \
                  __put_user_x(__r2, __p, __e, 4);          \
                  break;                                    \
            case 8:                                         \
                  __put_user_x(__r2, __p, __e, 8);          \
                  break;                                    \
            default: __e = __put_user_bad(); break;               \
            }                                         \
            __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)       (1)
#define __range_ok(addr,size) (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(x,p)   __put_user(x,p)

#endif /* CONFIG_MMU */

#define access_ok(type,addr,size)   (__range_ok(addr,size) == 0)

/*
 * 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;                               \
      __chk_user_ptr(ptr);                                  \
      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();                     \
      }                                               \
      (x) = (__typeof__(*(ptr)))__gu_val;                   \
} while (0)

#define __get_user_asm_byte(x,addr,err)                     \
      __asm__ __volatile__(                           \
      "1:   " T(ldrb) " %1,[%2],#0\n"                 \
      "2:\n"                                          \
      "     .pushsection .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")

#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)                     \
      __asm__ __volatile__(                           \
      "1:   " T(ldr) "  %1,[%2],#0\n"                 \
      "2:\n"                                          \
      "     .pushsection .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 __put_user(x,ptr)                                   \
({                                                    \
      long __pu_err = 0;                                    \
      __put_user_err((x),(ptr),__pu_err);                   \
      __pu_err;                                       \
})

#define __put_user_error(x,ptr,err)                         \
({                                                    \
      __put_user_err((x),(ptr),err);                              \
      (void) 0;                                       \
})

#define __put_user_err(x,ptr,err)                           \
do {                                                  \
      unsigned long __pu_addr = (unsigned long)(ptr);             \
      __typeof__(*(ptr)) __pu_val = (x);                    \
      __chk_user_ptr(ptr);                                  \
      switch (sizeof(*(ptr))) {                             \
      case 1: __put_user_asm_byte(__pu_val,__pu_addr,err);  break;      \
      case 2: __put_user_asm_half(__pu_val,__pu_addr,err);  break;      \
      case 4: __put_user_asm_word(__pu_val,__pu_addr,err);  break;      \
      case 8:     __put_user_asm_dword(__pu_val,__pu_addr,err);   break;      \
      default: __put_user_bad();                            \
      }                                               \
} while (0)

#define __put_user_asm_byte(x,__pu_addr,err)                \
      __asm__ __volatile__(                           \
      "1:   " T(strb) " %1,[%2],#0\n"                 \
      "2:\n"                                          \
      "     .pushsection .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")

#ifndef __ARMEB__
#define __put_user_asm_half(x,__pu_addr,err)                \
({                                              \
      unsigned long __temp = (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 = (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)                \
      __asm__ __volatile__(                           \
      "1:   " T(str) "  %1,[%2],#0\n"                 \
      "2:\n"                                          \
      "     .pushsection .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")

#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:   " T(str) "  " __reg_oper1 ", [%1], #4\n"  )     \
 ARM( "2:   " T(str) "  " __reg_oper0 ", [%1]\n"      )     \
 THUMB(     "1:   " T(str) "  " __reg_oper1 ", [%1]\n"      )     \
 THUMB(     "2:   " T(str) "  " __reg_oper0 ", [%1, #4]\n"  )     \
      "3:\n"                                          \
      "     .pushsection .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 __copy_from_user(void *to, const void __user *from, unsigned long n);
extern unsigned long __must_check __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);
extern unsigned long __must_check __clear_user(void __user *addr, unsigned long n);
extern unsigned long __must_check __clear_user_std(void __user *addr, unsigned long n);
#else
#define __copy_from_user(to,from,n) (memcpy(to, (void __force *)from, n), 0)
#define __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

extern unsigned long __must_check __strncpy_from_user(char *to, const char __user *from, unsigned long count);
extern unsigned long __must_check __strnlen_user(const char __user *s, long n);

static inline unsigned long __must_check copy_from_user(void *to, const void __user *from, unsigned long n)
{
      if (access_ok(VERIFY_READ, from, n))
            n = __copy_from_user(to, from, n);
      else /* security hole - plug it */
            memset(to, 0, n);
      return n;
}

static inline unsigned long __must_check copy_to_user(void __user *to, const void *from, unsigned long n)
{
      if (access_ok(VERIFY_WRITE, to, n))
            n = __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;
}

static inline long __must_check strncpy_from_user(char *dst, const char __user *src, long count)
{
      long res = -EFAULT;
      if (access_ok(VERIFY_READ, src, 1))
            res = __strncpy_from_user(dst, src, count);
      return res;
}

#define strlen_user(s)  strnlen_user(s, ~0UL >> 1)

static inline long __must_check strnlen_user(const char __user *s, long n)
{
      unsigned long res = 0;

      if (__addr_ok(s))
            res = __strnlen_user(s, n);

      return res;
}

#endif /* _ASMARM_UACCESS_H */

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