501 lines
14 KiB
C
501 lines
14 KiB
C
/*
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* include/asm-xtensa/uaccess.h
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*
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* User space memory access functions
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*
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* These routines provide basic accessing functions to the user memory
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* space for the kernel. This header file provides functions such as:
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*
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* This file is subject to the terms and conditions of the GNU General Public
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* License. See the file "COPYING" in the main directory of this archive
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* for more details.
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*
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* Copyright (C) 2001 - 2005 Tensilica Inc.
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*/
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#ifndef _XTENSA_UACCESS_H
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#define _XTENSA_UACCESS_H
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#include <linux/errno.h>
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#include <linux/prefetch.h>
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#include <asm/types.h>
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#define VERIFY_READ 0
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#define VERIFY_WRITE 1
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#ifdef __ASSEMBLY__
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#include <asm/current.h>
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#include <asm/asm-offsets.h>
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#include <asm/processor.h>
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/*
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* These assembly macros mirror the C macros that follow below. They
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* should always have identical functionality. See
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* arch/xtensa/kernel/sys.S for usage.
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*/
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#define KERNEL_DS 0
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#define USER_DS 1
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#define get_ds (KERNEL_DS)
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/*
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* get_fs reads current->thread.current_ds into a register.
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* On Entry:
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* <ad> anything
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* <sp> stack
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* On Exit:
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* <ad> contains current->thread.current_ds
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*/
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.macro get_fs ad, sp
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GET_CURRENT(\ad,\sp)
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l32i \ad, \ad, THREAD_CURRENT_DS
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.endm
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/*
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* set_fs sets current->thread.current_ds to some value.
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* On Entry:
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* <at> anything (temp register)
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* <av> value to write
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* <sp> stack
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* On Exit:
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* <at> destroyed (actually, current)
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* <av> preserved, value to write
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*/
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.macro set_fs at, av, sp
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GET_CURRENT(\at,\sp)
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s32i \av, \at, THREAD_CURRENT_DS
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.endm
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/*
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* kernel_ok determines whether we should bypass addr/size checking.
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* See the equivalent C-macro version below for clarity.
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* On success, kernel_ok branches to a label indicated by parameter
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* <success>. This implies that the macro falls through to the next
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* insruction on an error.
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*
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* Note that while this macro can be used independently, we designed
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* in for optimal use in the access_ok macro below (i.e., we fall
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* through on error).
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*
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* On Entry:
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* <at> anything (temp register)
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* <success> label to branch to on success; implies
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* fall-through macro on error
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* <sp> stack pointer
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* On Exit:
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* <at> destroyed (actually, current->thread.current_ds)
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*/
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#if ((KERNEL_DS != 0) || (USER_DS == 0))
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# error Assembly macro kernel_ok fails
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#endif
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.macro kernel_ok at, sp, success
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get_fs \at, \sp
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beqz \at, \success
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.endm
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/*
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* user_ok determines whether the access to user-space memory is allowed.
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* See the equivalent C-macro version below for clarity.
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*
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* On error, user_ok branches to a label indicated by parameter
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* <error>. This implies that the macro falls through to the next
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* instruction on success.
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*
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* Note that while this macro can be used independently, we designed
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* in for optimal use in the access_ok macro below (i.e., we fall
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* through on success).
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*
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* On Entry:
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* <aa> register containing memory address
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* <as> register containing memory size
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* <at> temp register
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* <error> label to branch to on error; implies fall-through
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* macro on success
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* On Exit:
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* <aa> preserved
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* <as> preserved
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* <at> destroyed (actually, (TASK_SIZE + 1 - size))
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*/
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.macro user_ok aa, as, at, error
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movi \at, __XTENSA_UL_CONST(TASK_SIZE)
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bgeu \as, \at, \error
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sub \at, \at, \as
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bgeu \aa, \at, \error
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.endm
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/*
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* access_ok determines whether a memory access is allowed. See the
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* equivalent C-macro version below for clarity.
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*
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* On error, access_ok branches to a label indicated by parameter
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* <error>. This implies that the macro falls through to the next
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* instruction on success.
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*
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* Note that we assume success is the common case, and we optimize the
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* branch fall-through case on success.
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*
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* On Entry:
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* <aa> register containing memory address
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* <as> register containing memory size
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* <at> temp register
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* <sp>
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* <error> label to branch to on error; implies fall-through
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* macro on success
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* On Exit:
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* <aa> preserved
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* <as> preserved
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* <at> destroyed
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*/
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.macro access_ok aa, as, at, sp, error
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kernel_ok \at, \sp, .Laccess_ok_\@
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user_ok \aa, \as, \at, \error
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.Laccess_ok_\@:
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.endm
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#else /* __ASSEMBLY__ not defined */
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#include <linux/sched.h>
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/*
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* The fs value determines whether argument validity checking should
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* be performed or not. If get_fs() == USER_DS, checking is
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* performed, with get_fs() == KERNEL_DS, checking is bypassed.
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*
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* For historical reasons (Data Segment Register?), these macros are
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* grossly misnamed.
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*/
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#define KERNEL_DS ((mm_segment_t) { 0 })
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#define USER_DS ((mm_segment_t) { 1 })
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#define get_ds() (KERNEL_DS)
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#define get_fs() (current->thread.current_ds)
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#define set_fs(val) (current->thread.current_ds = (val))
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#define segment_eq(a,b) ((a).seg == (b).seg)
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#define __kernel_ok (segment_eq(get_fs(), KERNEL_DS))
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#define __user_ok(addr,size) (((size) <= TASK_SIZE)&&((addr) <= TASK_SIZE-(size)))
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#define __access_ok(addr,size) (__kernel_ok || __user_ok((addr),(size)))
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#define access_ok(type,addr,size) __access_ok((unsigned long)(addr),(size))
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/*
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* These are the main single-value transfer routines. They
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* automatically use the right size if we just have the right pointer
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* type.
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*
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* This gets kind of ugly. We want to return _two_ values in
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* "get_user()" and yet we don't want to do any pointers, because that
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* is too much of a performance impact. Thus we have a few rather ugly
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* macros here, and hide all the uglyness from the user.
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*
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* Careful to not
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* (a) re-use the arguments for side effects (sizeof is ok)
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* (b) require any knowledge of processes at this stage
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*/
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#define put_user(x,ptr) __put_user_check((x),(ptr),sizeof(*(ptr)))
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#define get_user(x,ptr) __get_user_check((x),(ptr),sizeof(*(ptr)))
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/*
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* The "__xxx" versions of the user access functions are versions that
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* do not verify the address space, that must have been done previously
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* with a separate "access_ok()" call (this is used when we do multiple
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* accesses to the same area of user memory).
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*/
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#define __put_user(x,ptr) __put_user_nocheck((x),(ptr),sizeof(*(ptr)))
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#define __get_user(x,ptr) __get_user_nocheck((x),(ptr),sizeof(*(ptr)))
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extern long __put_user_bad(void);
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#define __put_user_nocheck(x,ptr,size) \
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({ \
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long __pu_err; \
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__put_user_size((x),(ptr),(size),__pu_err); \
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__pu_err; \
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})
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#define __put_user_check(x,ptr,size) \
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({ \
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long __pu_err = -EFAULT; \
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__typeof__(*(ptr)) *__pu_addr = (ptr); \
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if (access_ok(VERIFY_WRITE,__pu_addr,size)) \
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__put_user_size((x),__pu_addr,(size),__pu_err); \
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__pu_err; \
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})
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#define __put_user_size(x,ptr,size,retval) \
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do { \
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int __cb; \
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retval = 0; \
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switch (size) { \
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case 1: __put_user_asm(x,ptr,retval,1,"s8i",__cb); break; \
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case 2: __put_user_asm(x,ptr,retval,2,"s16i",__cb); break; \
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case 4: __put_user_asm(x,ptr,retval,4,"s32i",__cb); break; \
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case 8: { \
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__typeof__(*ptr) __v64 = x; \
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retval = __copy_to_user(ptr,&__v64,8); \
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break; \
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} \
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default: __put_user_bad(); \
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} \
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} while (0)
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/*
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* Consider a case of a user single load/store would cause both an
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* unaligned exception and an MMU-related exception (unaligned
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* exceptions happen first):
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*
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* User code passes a bad variable ptr to a system call.
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* Kernel tries to access the variable.
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* Unaligned exception occurs.
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* Unaligned exception handler tries to make aligned accesses.
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* Double exception occurs for MMU-related cause (e.g., page not mapped).
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* do_page_fault() thinks the fault address belongs to the kernel, not the
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* user, and panics.
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*
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* The kernel currently prohibits user unaligned accesses. We use the
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* __check_align_* macros to check for unaligned addresses before
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* accessing user space so we don't crash the kernel. Both
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* __put_user_asm and __get_user_asm use these alignment macros, so
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* macro-specific labels such as 0f, 1f, %0, %2, and %3 must stay in
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* sync.
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*/
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#define __check_align_1 ""
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#define __check_align_2 \
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" _bbci.l %3, 0, 1f \n" \
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" movi %0, %4 \n" \
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" _j 2f \n"
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#define __check_align_4 \
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" _bbsi.l %3, 0, 0f \n" \
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" _bbci.l %3, 1, 1f \n" \
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"0: movi %0, %4 \n" \
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" _j 2f \n"
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/*
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* We don't tell gcc that we are accessing memory, but this is OK
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* because we do not write to any memory gcc knows about, so there
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* are no aliasing issues.
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*
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* WARNING: If you modify this macro at all, verify that the
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* __check_align_* macros still work.
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*/
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#define __put_user_asm(x, addr, err, align, insn, cb) \
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__asm__ __volatile__( \
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__check_align_##align \
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"1: "insn" %2, %3, 0 \n" \
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"2: \n" \
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" .section .fixup,\"ax\" \n" \
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" .align 4 \n" \
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"4: \n" \
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" .long 2b \n" \
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"5: \n" \
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" l32r %1, 4b \n" \
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" movi %0, %4 \n" \
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" jx %1 \n" \
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" .previous \n" \
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" .section __ex_table,\"a\" \n" \
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" .long 1b, 5b \n" \
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" .previous" \
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:"=r" (err), "=r" (cb) \
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:"r" ((int)(x)), "r" (addr), "i" (-EFAULT), "0" (err))
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#define __get_user_nocheck(x,ptr,size) \
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({ \
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long __gu_err, __gu_val; \
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__get_user_size(__gu_val,(ptr),(size),__gu_err); \
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(x) = (__typeof__(*(ptr)))__gu_val; \
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__gu_err; \
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})
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#define __get_user_check(x,ptr,size) \
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({ \
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long __gu_err = -EFAULT, __gu_val = 0; \
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const __typeof__(*(ptr)) *__gu_addr = (ptr); \
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if (access_ok(VERIFY_READ,__gu_addr,size)) \
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__get_user_size(__gu_val,__gu_addr,(size),__gu_err); \
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(x) = (__typeof__(*(ptr)))__gu_val; \
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__gu_err; \
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})
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extern long __get_user_bad(void);
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#define __get_user_size(x,ptr,size,retval) \
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do { \
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int __cb; \
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retval = 0; \
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switch (size) { \
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case 1: __get_user_asm(x,ptr,retval,1,"l8ui",__cb); break; \
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case 2: __get_user_asm(x,ptr,retval,2,"l16ui",__cb); break; \
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case 4: __get_user_asm(x,ptr,retval,4,"l32i",__cb); break; \
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case 8: retval = __copy_from_user(&x,ptr,8); break; \
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default: (x) = __get_user_bad(); \
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} \
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} while (0)
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/*
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* WARNING: If you modify this macro at all, verify that the
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* __check_align_* macros still work.
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*/
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#define __get_user_asm(x, addr, err, align, insn, cb) \
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__asm__ __volatile__( \
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__check_align_##align \
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"1: "insn" %2, %3, 0 \n" \
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"2: \n" \
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" .section .fixup,\"ax\" \n" \
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" .align 4 \n" \
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"4: \n" \
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" .long 2b \n" \
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"5: \n" \
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" l32r %1, 4b \n" \
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" movi %2, 0 \n" \
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" movi %0, %4 \n" \
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" jx %1 \n" \
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" .previous \n" \
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" .section __ex_table,\"a\" \n" \
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" .long 1b, 5b \n" \
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" .previous" \
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:"=r" (err), "=r" (cb), "=r" (x) \
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:"r" (addr), "i" (-EFAULT), "0" (err))
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/*
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* Copy to/from user space
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*/
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/*
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* We use a generic, arbitrary-sized copy subroutine. The Xtensa
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* architecture would cause heavy code bloat if we tried to inline
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* these functions and provide __constant_copy_* equivalents like the
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* i386 versions. __xtensa_copy_user is quite efficient. See the
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* .fixup section of __xtensa_copy_user for a discussion on the
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* X_zeroing equivalents for Xtensa.
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*/
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extern unsigned __xtensa_copy_user(void *to, const void *from, unsigned n);
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#define __copy_user(to,from,size) __xtensa_copy_user(to,from,size)
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static inline unsigned long
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__generic_copy_from_user_nocheck(void *to, const void *from, unsigned long n)
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{
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return __copy_user(to,from,n);
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}
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static inline unsigned long
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__generic_copy_to_user_nocheck(void *to, const void *from, unsigned long n)
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{
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return __copy_user(to,from,n);
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}
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static inline unsigned long
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__generic_copy_to_user(void *to, const void *from, unsigned long n)
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{
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prefetch(from);
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if (access_ok(VERIFY_WRITE, to, n))
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return __copy_user(to,from,n);
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return n;
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}
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static inline unsigned long
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__generic_copy_from_user(void *to, const void *from, unsigned long n)
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{
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prefetchw(to);
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if (access_ok(VERIFY_READ, from, n))
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return __copy_user(to,from,n);
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else
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memset(to, 0, n);
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return n;
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}
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#define copy_to_user(to,from,n) __generic_copy_to_user((to),(from),(n))
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#define copy_from_user(to,from,n) __generic_copy_from_user((to),(from),(n))
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#define __copy_to_user(to,from,n) __generic_copy_to_user_nocheck((to),(from),(n))
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#define __copy_from_user(to,from,n) __generic_copy_from_user_nocheck((to),(from),(n))
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#define __copy_to_user_inatomic __copy_to_user
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#define __copy_from_user_inatomic __copy_from_user
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/*
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* We need to return the number of bytes not cleared. Our memset()
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* returns zero if a problem occurs while accessing user-space memory.
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* In that event, return no memory cleared. Otherwise, zero for
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* success.
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*/
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static inline unsigned long
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__xtensa_clear_user(void *addr, unsigned long size)
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{
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if ( ! memset(addr, 0, size) )
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return size;
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return 0;
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}
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static inline unsigned long
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clear_user(void *addr, unsigned long size)
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{
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if (access_ok(VERIFY_WRITE, addr, size))
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return __xtensa_clear_user(addr, size);
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return size ? -EFAULT : 0;
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}
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#define __clear_user __xtensa_clear_user
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extern long __strncpy_user(char *, const char *, long);
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#define __strncpy_from_user __strncpy_user
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static inline long
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strncpy_from_user(char *dst, const char *src, long count)
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{
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if (access_ok(VERIFY_READ, src, 1))
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return __strncpy_from_user(dst, src, count);
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return -EFAULT;
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}
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#define strlen_user(str) strnlen_user((str), TASK_SIZE - 1)
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/*
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* Return the size of a string (including the ending 0!)
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*/
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extern long __strnlen_user(const char *, long);
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static inline long strnlen_user(const char *str, long len)
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{
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unsigned long top = __kernel_ok ? ~0UL : TASK_SIZE - 1;
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if ((unsigned long)str > top)
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return 0;
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return __strnlen_user(str, len);
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}
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struct exception_table_entry
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{
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unsigned long insn, fixup;
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};
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/* Returns 0 if exception not found and fixup.unit otherwise. */
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extern unsigned long search_exception_table(unsigned long addr);
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extern void sort_exception_table(void);
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/* Returns the new pc */
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#define fixup_exception(map_reg, fixup_unit, pc) \
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({ \
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fixup_unit; \
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})
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#endif /* __ASSEMBLY__ */
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#endif /* _XTENSA_UACCESS_H */
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