forked from luck/tmp_suning_uos_patched
96d4f267e4
Nobody has actually used the type (VERIFY_READ vs VERIFY_WRITE) argument
of the user address range verification function since we got rid of the
old racy i386-only code to walk page tables by hand.
It existed because the original 80386 would not honor the write protect
bit when in kernel mode, so you had to do COW by hand before doing any
user access. But we haven't supported that in a long time, and these
days the 'type' argument is a purely historical artifact.
A discussion about extending 'user_access_begin()' to do the range
checking resulted this patch, because there is no way we're going to
move the old VERIFY_xyz interface to that model. And it's best done at
the end of the merge window when I've done most of my merges, so let's
just get this done once and for all.
This patch was mostly done with a sed-script, with manual fix-ups for
the cases that weren't of the trivial 'access_ok(VERIFY_xyz' form.
There were a couple of notable cases:
- csky still had the old "verify_area()" name as an alias.
- the iter_iov code had magical hardcoded knowledge of the actual
values of VERIFY_{READ,WRITE} (not that they mattered, since nothing
really used it)
- microblaze used the type argument for a debug printout
but other than those oddities this should be a total no-op patch.
I tried to fix up all architectures, did fairly extensive grepping for
access_ok() uses, and the changes are trivial, but I may have missed
something. Any missed conversion should be trivially fixable, though.
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
59 lines
1.8 KiB
C
59 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 = raw_copy_to_user(dest, &empty_zero_page, 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 = raw_copy_to_user(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(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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