uaccess.c
1.79 KB
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/*
* Copyright (c) 2010-2011, The Linux Foundation. All rights reserved.
*
* This program is free software; you can redistribute it and/or modify
* it under the terms of the GNU General Public License version 2 and
* only version 2 as published by the Free Software Foundation.
*
* This program is distributed in the hope that it will be useful,
* but WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
* GNU General Public License for more details.
*
* You should have received a copy of the GNU General Public License
* along with this program; if not, write to the Free Software
* Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA
* 02110-1301, USA.
*/
/*
* Support for user memory access from kernel. This will
* probably be inlined for performance at some point, but
* for ease of debug, and to a lesser degree for code size,
* we implement here as subroutines.
*/
#include <linux/types.h>
#include <asm/uaccess.h>
#include <asm/pgtable.h>
/*
* For clear_user(), exploit previously defined copy_to_user function
* and the fact that we've got a handy zero page defined in kernel/head.S
*
* dczero here would be even faster.
*/
__kernel_size_t __clear_user_hexagon(void __user *dest, unsigned long count)
{
long uncleared;
while (count > PAGE_SIZE) {
uncleared = __copy_to_user_hexagon(dest, &empty_zero_page,
PAGE_SIZE);
if (uncleared)
return count - (PAGE_SIZE - uncleared);
count -= PAGE_SIZE;
dest += PAGE_SIZE;
}
if (count)
count = __copy_to_user_hexagon(dest, &empty_zero_page, count);
return count;
}
unsigned long clear_user_hexagon(void __user *dest, unsigned long count)
{
if (!access_ok(VERIFY_WRITE, dest, count))
return count;
else
return __clear_user_hexagon(dest, count);
}