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