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