[linux-2.6-block.git] / arch / xtensa / include / asm / asm-uaccess.h

/*
 * 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 */
Commit	Line	Data
76580237 AV	1	/*
	2	* include/asm-xtensa/uaccess.h
	3	*
	4	* User space memory access functions
	5	*
	6	* These routines provide basic accessing functions to the user memory
	7	* space for the kernel. This header file provides functions such as:
	8	*
	9	* This file is subject to the terms and conditions of the GNU General Public
	10	* License. See the file "COPYING" in the main directory of this archive
	11	* for more details.
	12	*
	13	* Copyright (C) 2001 - 2005 Tensilica Inc.
	14	*/
	15
	16	#ifndef _XTENSA_ASM_UACCESS_H
	17	#define _XTENSA_ASM_UACCESS_H
	18
	19	#include <linux/errno.h>
	20	#include <asm/types.h>
	21
76580237 AV	22	#include <asm/current.h>
	23	#include <asm/asm-offsets.h>
	24	#include <asm/processor.h>
	25
	26	/*
	27	* These assembly macros mirror the C macros in asm/uaccess.h. They
	28	* should always have identical functionality. See
	29	* arch/xtensa/kernel/sys.S for usage.
	30	*/
	31
	32	#define KERNEL_DS 0
	33	#define USER_DS 1
	34
76580237 AV	35	/*
	36	* get_fs reads current->thread.current_ds into a register.
	37	* On Entry:
	38	* <ad> anything
	39	* <sp> stack
	40	* On Exit:
	41	* <ad> contains current->thread.current_ds
	42	*/
	43	.macro get_fs ad, sp
	44	GET_CURRENT(\ad,\sp)
	45	#if THREAD_CURRENT_DS > 1020
	46	addi \ad, \ad, TASK_THREAD
	47	l32i \ad, \ad, THREAD_CURRENT_DS - TASK_THREAD
	48	#else
	49	l32i \ad, \ad, THREAD_CURRENT_DS
	50	#endif
	51	.endm
	52
	53	/*
	54	* set_fs sets current->thread.current_ds to some value.
	55	* On Entry:
	56	* <at> anything (temp register)
	57	* <av> value to write
	58	* <sp> stack
	59	* On Exit:
	60	* <at> destroyed (actually, current)
	61	* <av> preserved, value to write
	62	*/
	63	.macro set_fs at, av, sp
	64	GET_CURRENT(\at,\sp)
	65	s32i \av, \at, THREAD_CURRENT_DS
	66	.endm
	67
	68	/*
	69	* kernel_ok determines whether we should bypass addr/size checking.
	70	* See the equivalent C-macro version below for clarity.
	71	* On success, kernel_ok branches to a label indicated by parameter
	72	* <success>. This implies that the macro falls through to the next
	73	* insruction on an error.
	74	*
	75	* Note that while this macro can be used independently, we designed
	76	* in for optimal use in the access_ok macro below (i.e., we fall
	77	* through on error).
	78	*
	79	* On Entry:
	80	* <at> anything (temp register)
	81	* <success> label to branch to on success; implies
	82	* fall-through macro on error
	83	* <sp> stack pointer
	84	* On Exit:
	85	* <at> destroyed (actually, current->thread.current_ds)
	86	*/
	87
	88	#if ((KERNEL_DS != 0) \|\| (USER_DS == 0))
	89	# error Assembly macro kernel_ok fails
	90	#endif
	91	.macro kernel_ok at, sp, success
	92	get_fs \at, \sp
	93	beqz \at, \success
	94	.endm
	95
	96	/*
	97	* user_ok determines whether the access to user-space memory is allowed.
	98	* See the equivalent C-macro version below for clarity.
99	*
100	* On error, user_ok branches to a label indicated by parameter
101	* <error>. This implies that the macro falls through to the next
102	* instruction on success.
103	*
104	* Note that while this macro can be used independently, we designed
105	* in for optimal use in the access_ok macro below (i.e., we fall
106	* through on success).
107	*
108	* On Entry:
109	* <aa> register containing memory address
110	* <as> register containing memory size
111	* <at> temp register
112	* <error> label to branch to on error; implies fall-through
113	* macro on success
114	* On Exit:
115	* <aa> preserved
116	* <as> preserved
117	* <at> destroyed (actually, (TASK_SIZE + 1 - size))
118	*/
119	.macro user_ok aa, as, at, error
120	movi \at, __XTENSA_UL_CONST(TASK_SIZE)
121	bgeu \as, \at, \error
122	sub \at, \at, \as
123	bgeu \aa, \at, \error
124	.endm
125
126	/*
127	* access_ok determines whether a memory access is allowed. See the
128	* equivalent C-macro version below for clarity.
129	*
130	* On error, access_ok branches to a label indicated by parameter
131	* <error>. This implies that the macro falls through to the next
132	* instruction on success.
133	*
134	* Note that we assume success is the common case, and we optimize the
135	* branch fall-through case on success.
136	*
137	* On Entry:
138	* <aa> register containing memory address
139	* <as> register containing memory size
140	* <at> temp register
141	* <sp>
142	* <error> label to branch to on error; implies fall-through
143	* macro on success
144	* On Exit:
145	* <aa> preserved
146	* <as> preserved
147	* <at> destroyed
148	*/
149	.macro access_ok aa, as, at, sp, error
150	kernel_ok \at, \sp, .Laccess_ok_\@
151	user_ok \aa, \as, \at, \error
152	.Laccess_ok_\@:
153	.endm
154
155	#endif /* _XTENSA_ASM_UACCESS_H */