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/*
* User memory access support for Hexagon
*
* 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.
*/
#ifndef _ASM_UACCESS_H
#define _ASM_UACCESS_H
/*
* User space memory access functions
*/
#include <linux/sched.h>
#include <linux/mm.h>
#include <asm/segment.h>
#include <asm/sections.h>
/*
* access_ok: - Checks if a user space pointer is valid
* @type: Type of access: %VERIFY_READ or %VERIFY_WRITE. Note that
* %VERIFY_WRITE is a superset of %VERIFY_READ - if it is safe
* to write to a block, it is always safe to read from it.
* @addr: User space pointer to start of block to check
* @size: Size of block to check
*
* Context: User context only. This function may sleep if pagefaults are
* enabled.
*
* Checks if a pointer to a block of memory in user space is valid.
*
* Returns true (nonzero) if the memory block *may* be valid, false (zero)
* if it is definitely invalid.
*
* User address space in Hexagon, like x86, goes to 0xbfffffff, so the
* simple MSB-based tests used by MIPS won't work. Some further
* optimization is probably possible here, but for now, keep it
* reasonably simple and not *too* slow. After all, we've got the
* MMU for backup.
*/
#define VERIFY_READ 0
#define VERIFY_WRITE 1
#define __access_ok(addr, size) \
((get_fs().seg == KERNEL_DS.seg) || \
(((unsigned long)addr < get_fs().seg) && \
(unsigned long)size < (get_fs().seg - (unsigned long)addr)))
/*
* When a kernel-mode page fault is taken, the faulting instruction
* address is checked against a table of exception_table_entries.
* Each entry is a tuple of the address of an instruction that may
* be authorized to fault, and the address at which execution should
* be resumed instead of the faulting instruction, so as to effect
* a workaround.
*/
/* Assembly somewhat optimized copy routines */
unsigned long __copy_from_user_hexagon(void *to, const void __user *from,
unsigned long n);
unsigned long __copy_to_user_hexagon(void __user *to, const void *from,
unsigned long n);
#define __copy_from_user(to, from, n) __copy_from_user_hexagon(to, from, n)
#define __copy_to_user(to, from, n) __copy_to_user_hexagon(to, from, n)
/*
* XXX todo: some additonal performance gain is possible by
* implementing __copy_to/from_user_inatomic, which is much
* like __copy_to/from_user, but performs slightly less checking.
*/
__kernel_size_t __clear_user_hexagon(void __user *dest, unsigned long count);
#define __clear_user(a, s) __clear_user_hexagon((a), (s))
#define __strncpy_from_user(dst, src, n) hexagon_strncpy_from_user(dst, src, n)
/* get around the ifndef in asm-generic/uaccess.h */
#define __strnlen_user __strnlen_user
extern long __strnlen_user(const char __user *src, long n);
static inline long hexagon_strncpy_from_user(char *dst, const char __user *src,
long n);
#include <asm-generic/uaccess.h>
/* Todo: an actual accelerated version of this. */
static inline long hexagon_strncpy_from_user(char *dst, const char __user *src,
long n)
{
long res = __strnlen_user(src, n);
/* return from strnlen can't be zero -- that would be rubbish. */
if (res > n) {
copy_from_user(dst, src, n);
return n;
} else {
copy_from_user(dst, src, res);
return res-1;
}
}
#endif
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