arch/hexagon/include/asm/uaccess.h

   1 /* SPDX-License-Identifier: GPL-2.0-only */
   2 /*
   3  * User memory access support for Hexagon
   4  *
   5  * Copyright (c) 2010-2011, The Linux Foundation. All rights reserved.
   6  */
   7
   8 #ifndef _ASM_UACCESS_H
   9 #define _ASM_UACCESS_H
  10 /*
  11  * User space memory access functions
  12  */
  13 #include <asm/sections.h>
  14
  15 /*
  16  * access_ok: - Checks if a user space pointer is valid
  17  * @addr: User space pointer to start of block to check
  18  * @size: Size of block to check
  19  *
  20  * Context: User context only. This function may sleep if pagefaults are
  21  *          enabled.
  22  *
  23  * Checks if a pointer to a block of memory in user space is valid.
  24  *
  25  * Returns true (nonzero) if the memory block *may* be valid, false (zero)
  26  * if it is definitely invalid.
  27  *
  28  * User address space in Hexagon, like x86, goes to 0xbfffffff, so the
  29  * simple MSB-based tests used by MIPS won't work.  Some further
  30  * optimization is probably possible here, but for now, keep it
  31  * reasonably simple and not *too* slow.  After all, we've got the
  32  * MMU for backup.
  33  */
  34
  35 #define __access_ok(addr, size) \
  36         ((get_fs().seg == KERNEL_DS.seg) || \
  37         (((unsigned long)addr < get_fs().seg) && \
  38           (unsigned long)size < (get_fs().seg - (unsigned long)addr)))
  39
  40 /*
  41  * When a kernel-mode page fault is taken, the faulting instruction
  42  * address is checked against a table of exception_table_entries.
  43  * Each entry is a tuple of the address of an instruction that may
  44  * be authorized to fault, and the address at which execution should
  45  * be resumed instead of the faulting instruction, so as to effect
  46  * a workaround.
  47  */
  48
  49 /*  Assembly somewhat optimized copy routines  */
  50 unsigned long raw_copy_from_user(void *to, const void __user *from,
  51                                      unsigned long n);
  52 unsigned long raw_copy_to_user(void __user *to, const void *from,
  53                                    unsigned long n);
  54 #define INLINE_COPY_FROM_USER
  55 #define INLINE_COPY_TO_USER
  56
  57 __kernel_size_t __clear_user_hexagon(void __user *dest, unsigned long count);
  58 #define __clear_user(a, s) __clear_user_hexagon((a), (s))
  59
  60 #define __strncpy_from_user(dst, src, n) hexagon_strncpy_from_user(dst, src, n)
  61
  62 /*  get around the ifndef in asm-generic/uaccess.h  */
  63 #define __strnlen_user __strnlen_user
  64
  65 extern long __strnlen_user(const char __user *src, long n);
  66
  67 static inline long hexagon_strncpy_from_user(char *dst, const char __user *src,
  68                                              long n);
  69
  70 #include <asm-generic/uaccess.h>
  71
  72 /*  Todo:  an actual accelerated version of this.  */
  73 static inline long hexagon_strncpy_from_user(char *dst, const char __user *src,
  74                                              long n)
  75 {
  76         long res = __strnlen_user(src, n);
  77
  78         if (unlikely(!res))
  79                 return -EFAULT;
  80
  81         if (res > n) {
  82                 long left = raw_copy_from_user(dst, src, n);
  83                 if (unlikely(left))
  84                         memset(dst + (n - left), 0, left);
  85                 return n;
  86         } else {
  87                 long left = raw_copy_from_user(dst, src, res);
  88                 if (unlikely(left))
  89                         memset(dst + (res - left), 0, left);
  90                 return res-1;
  91         }
  92 }
  93
  94 #endif