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/*
* include/asm-xtensa/uaccess.h
*
* User space memory access functions
*
* These routines provide basic accessing functions to the user memory
* space for the kernel. This header file provides functions such as:
*
* This file is subject to the terms and conditions of the GNU General Public
* License. See the file "COPYING" in the main directory of this archive
* for more details.
*
* Copyright (C) 2001 - 2005 Tensilica Inc.
*/
#ifndef _XTENSA_ASM_UACCESS_H
#define _XTENSA_ASM_UACCESS_H
#include <linux/errno.h>
#include <asm/types.h>
#include <asm/current.h>
#include <asm/asm-offsets.h>
#include <asm/processor.h>
/*
* These assembly macros mirror the C macros in asm/uaccess.h. They
* should always have identical functionality. See
* arch/xtensa/kernel/sys.S for usage.
*/
#define KERNEL_DS 0
#define USER_DS 1
/*
* get_fs reads current->thread.current_ds into a register.
* On Entry:
* <ad> anything
* <sp> stack
* On Exit:
* <ad> contains current->thread.current_ds
*/
.macro get_fs ad, sp
GET_CURRENT(\ad,\sp)
#if THREAD_CURRENT_DS > 1020
addi \ad, \ad, TASK_THREAD
l32i \ad, \ad, THREAD_CURRENT_DS - TASK_THREAD
#else
l32i \ad, \ad, THREAD_CURRENT_DS
#endif
.endm
/*
* set_fs sets current->thread.current_ds to some value.
* On Entry:
* <at> anything (temp register)
* <av> value to write
* <sp> stack
* On Exit:
* <at> destroyed (actually, current)
* <av> preserved, value to write
*/
.macro set_fs at, av, sp
GET_CURRENT(\at,\sp)
s32i \av, \at, THREAD_CURRENT_DS
.endm
/*
* kernel_ok determines whether we should bypass addr/size checking.
* See the equivalent C-macro version below for clarity.
* On success, kernel_ok branches to a label indicated by parameter
* <success>. This implies that the macro falls through to the next
* insruction on an error.
*
* Note that while this macro can be used independently, we designed
* in for optimal use in the access_ok macro below (i.e., we fall
* through on error).
*
* On Entry:
* <at> anything (temp register)
* <success> label to branch to on success; implies
* fall-through macro on error
* <sp> stack pointer
* On Exit:
* <at> destroyed (actually, current->thread.current_ds)
*/
#if ((KERNEL_DS != 0) || (USER_DS == 0))
# error Assembly macro kernel_ok fails
#endif
.macro kernel_ok at, sp, success
get_fs \at, \sp
beqz \at, \success
.endm
/*
* user_ok determines whether the access to user-space memory is allowed.
* See the equivalent C-macro version below for clarity.
*
* On error, user_ok branches to a label indicated by parameter
* <error>. This implies that the macro falls through to the next
* instruction on success.
*
* Note that while this macro can be used independently, we designed
* in for optimal use in the access_ok macro below (i.e., we fall
* through on success).
*
* On Entry:
* <aa> register containing memory address
* <as> register containing memory size
* <at> temp register
* <error> label to branch to on error; implies fall-through
* macro on success
* On Exit:
* <aa> preserved
* <as> preserved
* <at> destroyed (actually, (TASK_SIZE + 1 - size))
*/
.macro user_ok aa, as, at, error
movi \at, __XTENSA_UL_CONST(TASK_SIZE)
bgeu \as, \at, \error
sub \at, \at, \as
bgeu \aa, \at, \error
.endm
/*
* access_ok determines whether a memory access is allowed. See the
* equivalent C-macro version below for clarity.
*
* On error, access_ok branches to a label indicated by parameter
* <error>. This implies that the macro falls through to the next
* instruction on success.
*
* Note that we assume success is the common case, and we optimize the
* branch fall-through case on success.
*
* On Entry:
* <aa> register containing memory address
* <as> register containing memory size
* <at> temp register
* <sp>
* <error> label to branch to on error; implies fall-through
* macro on success
* On Exit:
* <aa> preserved
* <as> preserved
* <at> destroyed
*/
.macro access_ok aa, as, at, sp, error
kernel_ok \at, \sp, .Laccess_ok_\@
user_ok \aa, \as, \at, \error
.Laccess_ok_\@:
.endm
#endif /* _XTENSA_ASM_UACCESS_H */
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