linux/arch/hexagon/mm/uaccess.c
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   1// SPDX-License-Identifier: GPL-2.0-only
   2/*
   3 * Copyright (c) 2010-2011, The Linux Foundation. All rights reserved.
   4 */
   5
   6/*
   7 * Support for user memory access from kernel.  This will
   8 * probably be inlined for performance at some point, but
   9 * for ease of debug, and to a lesser degree for code size,
  10 * we implement here as subroutines.
  11 */
  12#include <linux/types.h>
  13#include <linux/uaccess.h>
  14#include <linux/pgtable.h>
  15
  16/*
  17 * For clear_user(), exploit previously defined copy_to_user function
  18 * and the fact that we've got a handy zero page defined in kernel/head.S
  19 *
  20 * dczero here would be even faster.
  21 */
  22__kernel_size_t __clear_user_hexagon(void __user *dest, unsigned long count)
  23{
  24        long uncleared;
  25
  26        while (count > PAGE_SIZE) {
  27                uncleared = raw_copy_to_user(dest, &empty_zero_page, PAGE_SIZE);
  28                if (uncleared)
  29                        return count - (PAGE_SIZE - uncleared);
  30                count -= PAGE_SIZE;
  31                dest += PAGE_SIZE;
  32        }
  33        if (count)
  34                count = raw_copy_to_user(dest, &empty_zero_page, count);
  35
  36        return count;
  37}
  38
  39unsigned long clear_user_hexagon(void __user *dest, unsigned long count)
  40{
  41        if (!access_ok(dest, count))
  42                return count;
  43        else
  44                return __clear_user_hexagon(dest, count);
  45}
  46