arch/hexagon/include/asm/uaccess.h

   1 /*
   2  * User memory access support for Hexagon
   3  *
   4  * Copyright (c) 2010-2011, The Linux Foundation. All rights reserved.
   5  *
   6  * This program is free software; you can redistribute it and/or modify
   7  * it under the terms of the GNU General Public License version 2 and
   8  * only version 2 as published by the Free Software Foundation.
   9  *
  10  * This program is distributed in the hope that it will be useful,
  11  * but WITHOUT ANY WARRANTY; without even the implied warranty of
  12  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  13  * GNU General Public License for more details.
  14  *
  15  * You should have received a copy of the GNU General Public License
  16  * along with this program; if not, write to the Free Software
  17  * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA
  18  * 02110-1301, USA.
  19  */
  20
  21 #ifndef _ASM_UACCESS_H
  22 #define _ASM_UACCESS_H
  23 /*
  24  * User space memory access functions
  25  */
  26 #include <linux/mm.h>
  27 #include <asm/segment.h>
  28 #include <asm/sections.h>
  29
  30 /*
  31  * access_ok: - Checks if a user space pointer is valid
  32  * @type: Type of access: %VERIFY_READ or %VERIFY_WRITE.  Note that
  33  *        %VERIFY_WRITE is a superset of %VERIFY_READ - if it is safe
  34  *        to write to a block, it is always safe to read from it.
  35  * @addr: User space pointer to start of block to check
  36  * @size: Size of block to check
  37  *
  38  * Context: User context only. This function may sleep if pagefaults are
  39  *          enabled.
  40  *
  41  * Checks if a pointer to a block of memory in user space is valid.
  42  *
  43  * Returns true (nonzero) if the memory block *may* be valid, false (zero)
  44  * if it is definitely invalid.
  45  *
  46  * User address space in Hexagon, like x86, goes to 0xbfffffff, so the
  47  * simple MSB-based tests used by MIPS won't work.  Some further
  48  * optimization is probably possible here, but for now, keep it
  49  * reasonably simple and not *too* slow.  After all, we've got the
  50  * MMU for backup.
  51  */
  52
  53 #define __access_ok(addr, size) \
  54         ((get_fs().seg == KERNEL_DS.seg) || \
  55         (((unsigned long)addr < get_fs().seg) && \
  56           (unsigned long)size < (get_fs().seg - (unsigned long)addr)))
  57
  58 /*
  59  * When a kernel-mode page fault is taken, the faulting instruction
  60  * address is checked against a table of exception_table_entries.
  61  * Each entry is a tuple of the address of an instruction that may
  62  * be authorized to fault, and the address at which execution should
  63  * be resumed instead of the faulting instruction, so as to effect
  64  * a workaround.
  65  */
  66
  67 /*  Assembly somewhat optimized copy routines  */
  68 unsigned long raw_copy_from_user(void *to, const void __user *from,
  69                                      unsigned long n);
  70 unsigned long raw_copy_to_user(void __user *to, const void *from,
  71                                    unsigned long n);
  72 #define INLINE_COPY_FROM_USER
  73 #define INLINE_COPY_TO_USER
  74
  75 __kernel_size_t __clear_user_hexagon(void __user *dest, unsigned long count);
  76 #define __clear_user(a, s) __clear_user_hexagon((a), (s))
  77
  78 #define __strncpy_from_user(dst, src, n) hexagon_strncpy_from_user(dst, src, n)
  79
  80 /*  get around the ifndef in asm-generic/uaccess.h  */
  81 #define __strnlen_user __strnlen_user
  82
  83 extern long __strnlen_user(const char __user *src, long n);
  84
  85 static inline long hexagon_strncpy_from_user(char *dst, const char __user *src,
  86                                              long n);
  87
  88 #include <asm-generic/uaccess.h>
  89
  90 /*  Todo:  an actual accelerated version of this.  */
  91 static inline long hexagon_strncpy_from_user(char *dst, const char __user *src,
  92                                              long n)
  93 {
  94         long res = __strnlen_user(src, n);
  95
  96         if (unlikely(!res))
  97                 return -EFAULT;
  98
  99         if (res > n) {
 100                 long left = raw_copy_from_user(dst, src, n);
 101                 if (unlikely(left))
 102                         memset(dst + (n - left), 0, left);
 103                 return n;
 104         } else {
 105                 long left = raw_copy_from_user(dst, src, res);
 106                 if (unlikely(left))
 107                         memset(dst + (res - left), 0, left);
 108                 return res-1;
 109         }
 110 }
 111
 112 #endif