LXR linux/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 <linux/mm.h>
  14#include <asm/sections.h>
  15
  16/*
  17 * access_ok: - Checks if a user space pointer is valid
  18 * @addr: User space pointer to start of block to check
  19 * @size: Size of block to check
  20 *
  21 * Context: User context only. This function may sleep if pagefaults are
  22 *          enabled.
  23 *
  24 * Checks if a pointer to a block of memory in user space is valid.
  25 *
  26 * Returns true (nonzero) if the memory block *may* be valid, false (zero)
  27 * if it is definitely invalid.
  28 *
  29 * User address space in Hexagon, like x86, goes to 0xbfffffff, so the
  30 * simple MSB-based tests used by MIPS won't work.  Some further
  31 * optimization is probably possible here, but for now, keep it
  32 * reasonably simple and not *too* slow.  After all, we've got the
  33 * MMU for backup.
  34 */
  35
  36#define __access_ok(addr, size) \
  37        ((get_fs().seg == KERNEL_DS.seg) || \
  38        (((unsigned long)addr < get_fs().seg) && \
  39          (unsigned long)size < (get_fs().seg - (unsigned long)addr)))
  40
  41/*
  42 * When a kernel-mode page fault is taken, the faulting instruction
  43 * address is checked against a table of exception_table_entries.
  44 * Each entry is a tuple of the address of an instruction that may
  45 * be authorized to fault, and the address at which execution should
  46 * be resumed instead of the faulting instruction, so as to effect
  47 * a workaround.
  48 */
  49
  50/*  Assembly somewhat optimized copy routines  */
  51unsigned long raw_copy_from_user(void *to, const void __user *from,
  52                                     unsigned long n);
  53unsigned long raw_copy_to_user(void __user *to, const void *from,
  54                                   unsigned long n);
  55#define INLINE_COPY_FROM_USER
  56#define INLINE_COPY_TO_USER
  57
  58__kernel_size_t __clear_user_hexagon(void __user *dest, unsigned long count);
  59#define __clear_user(a, s) __clear_user_hexagon((a), (s))
  60
  61#define __strncpy_from_user(dst, src, n) hexagon_strncpy_from_user(dst, src, n)
  62
  63/*  get around the ifndef in asm-generic/uaccess.h  */
  64#define __strnlen_user __strnlen_user
  65
  66extern long __strnlen_user(const char __user *src, long n);
  67
  68static inline long hexagon_strncpy_from_user(char *dst, const char __user *src,
  69                                             long n);
  70
  71#include <asm-generic/uaccess.h>
  72
  73/*  Todo:  an actual accelerated version of this.  */
  74static inline long hexagon_strncpy_from_user(char *dst, const char __user *src,
  75                                             long n)
  76{
  77        long res = __strnlen_user(src, n);
  78
  79        if (unlikely(!res))
  80                return -EFAULT;
  81
  82        if (res > n) {
  83                long left = raw_copy_from_user(dst, src, n);
  84                if (unlikely(left))
  85                        memset(dst + (n - left), 0, left);
  86                return n;
  87        } else {
  88                long left = raw_copy_from_user(dst, src, res);
  89                if (unlikely(left))
  90                        memset(dst + (res - left), 0, left);
  91                return res-1;
  92        }
  93}
  94
  95#endif
  96