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 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 35 #define get_ds (KERNEL_DS) 36 37 /* 38 * get_fs reads current->thread.current_ds into a register. 39 * On Entry: 40 * <ad> anything 41 * <sp> stack 42 * On Exit: 43 * <ad> contains current->thread.current_ds 44 */ 45 .macro get_fs ad, sp 46 GET_CURRENT(\ad,\sp) 47 #if THREAD_CURRENT_DS > 1020 48 addi \ad, \ad, TASK_THREAD 49 l32i \ad, \ad, THREAD_CURRENT_DS - TASK_THREAD 50 #else 51 l32i \ad, \ad, THREAD_CURRENT_DS 52 #endif 53 .endm 54 55 /* 56 * set_fs sets current->thread.current_ds to some value. 57 * On Entry: 58 * <at> anything (temp register) 59 * <av> value to write 60 * <sp> stack 61 * On Exit: 62 * <at> destroyed (actually, current) 63 * <av> preserved, value to write 64 */ 65 .macro set_fs at, av, sp 66 GET_CURRENT(\at,\sp) 67 s32i \av, \at, THREAD_CURRENT_DS 68 .endm 69 70 /* 71 * kernel_ok determines whether we should bypass addr/size checking. 72 * See the equivalent C-macro version below for clarity. 73 * On success, kernel_ok branches to a label indicated by parameter 74 * <success>. This implies that the macro falls through to the next 75 * insruction on an error. 76 * 77 * Note that while this macro can be used independently, we designed 78 * in for optimal use in the access_ok macro below (i.e., we fall 79 * through on error). 80 * 81 * On Entry: 82 * <at> anything (temp register) 83 * <success> label to branch to on success; implies 84 * fall-through macro on error 85 * <sp> stack pointer 86 * On Exit: 87 * <at> destroyed (actually, current->thread.current_ds) 88 */ 89 90 #if ((KERNEL_DS != 0) || (USER_DS == 0)) 91 # error Assembly macro kernel_ok fails 92 #endif 93 .macro kernel_ok at, sp, success 94 get_fs \at, \sp 95 beqz \at, \success 96 .endm 97 98 /* 99 * user_ok determines whether the access to user-space memory is allowed. 100 * See the equivalent C-macro version below for clarity. 101 * 102 * On error, user_ok branches to a label indicated by parameter 103 * <error>. This implies that the macro falls through to the next 104 * instruction on success. 105 * 106 * Note that while this macro can be used independently, we designed 107 * in for optimal use in the access_ok macro below (i.e., we fall 108 * through on success). 109 * 110 * On Entry: 111 * <aa> register containing memory address 112 * <as> register containing memory size 113 * <at> temp register 114 * <error> label to branch to on error; implies fall-through 115 * macro on success 116 * On Exit: 117 * <aa> preserved 118 * <as> preserved 119 * <at> destroyed (actually, (TASK_SIZE + 1 - size)) 120 */ 121 .macro user_ok aa, as, at, error 122 movi \at, __XTENSA_UL_CONST(TASK_SIZE) 123 bgeu \as, \at, \error 124 sub \at, \at, \as 125 bgeu \aa, \at, \error 126 .endm 127 128 /* 129 * access_ok determines whether a memory access is allowed. See the 130 * equivalent C-macro version below for clarity. 131 * 132 * On error, access_ok branches to a label indicated by parameter 133 * <error>. This implies that the macro falls through to the next 134 * instruction on success. 135 * 136 * Note that we assume success is the common case, and we optimize the 137 * branch fall-through case on success. 138 * 139 * On Entry: 140 * <aa> register containing memory address 141 * <as> register containing memory size 142 * <at> temp register 143 * <sp> 144 * <error> label to branch to on error; implies fall-through 145 * macro on success 146 * On Exit: 147 * <aa> preserved 148 * <as> preserved 149 * <at> destroyed 150 */ 151 .macro access_ok aa, as, at, sp, error 152 kernel_ok \at, \sp, .Laccess_ok_\@ 153 user_ok \aa, \as, \at, \error 154 .Laccess_ok_\@: 155 .endm 156 157 #endif /* _XTENSA_ASM_UACCESS_H */ 158