WIP FPC-III support
[linux/fpc-iii.git] / arch / xtensa / include / asm / asm-uaccess.h
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1 /*
2 * include/asm-xtensa/uaccess.h
4 * User space memory access functions
6 * These routines provide basic accessing functions to the user memory
7 * space for the kernel. This header file provides functions such as:
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.
13 * Copyright (C) 2001 - 2005 Tensilica Inc.
16 #ifndef _XTENSA_ASM_UACCESS_H
17 #define _XTENSA_ASM_UACCESS_H
19 #include <linux/errno.h>
20 #include <asm/types.h>
22 #include <asm/current.h>
23 #include <asm/asm-offsets.h>
24 #include <asm/processor.h>
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.
32 #define KERNEL_DS 0
33 #define USER_DS 1
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
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
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
63 .macro set_fs at, av, sp
64 GET_CURRENT(\at,\sp)
65 s32i \av, \at, THREAD_CURRENT_DS
66 .endm
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.
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).
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)
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
97 * user_ok determines whether the access to user-space memory is allowed.
98 * See the equivalent C-macro version below for clarity.
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.
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).
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))
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
127 * access_ok determines whether a memory access is allowed. See the
128 * equivalent C-macro version below for clarity.
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.
134 * Note that we assume success is the common case, and we optimize the
135 * branch fall-through case on success.
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
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
155 #endif /* _XTENSA_ASM_UACCESS_H */