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 #define VERIFY_READ 0 23 #define VERIFY_WRITE 1 24 25 #include <asm/current.h> 26 #include <asm/asm-offsets.h> 27 #include <asm/processor.h> 28 29 /* 30 * These assembly macros mirror the C macros in asm/uaccess.h. They 31 * should always have identical functionality. See 32 * arch/xtensa/kernel/sys.S for usage. 33 */ 34 35 #define KERNEL_DS 0 36 #define USER_DS 1 37 38 #define get_ds (KERNEL_DS) 39 40 /* 41 * get_fs reads current->thread.current_ds into a register. 42 * On Entry: 43 * <ad> anything 44 * <sp> stack 45 * On Exit: 46 * <ad> contains current->thread.current_ds 47 */ 48 .macro get_fs ad, sp 49 GET_CURRENT(\ad,\sp) 50 #if THREAD_CURRENT_DS > 1020 51 addi \ad, \ad, TASK_THREAD 52 l32i \ad, \ad, THREAD_CURRENT_DS - TASK_THREAD 53 #else 54 l32i \ad, \ad, THREAD_CURRENT_DS 55 #endif 56 .endm 57 58 /* 59 * set_fs sets current->thread.current_ds to some value. 60 * On Entry: 61 * <at> anything (temp register) 62 * <av> value to write 63 * <sp> stack 64 * On Exit: 65 * <at> destroyed (actually, current) 66 * <av> preserved, value to write 67 */ 68 .macro set_fs at, av, sp 69 GET_CURRENT(\at,\sp) 70 s32i \av, \at, THREAD_CURRENT_DS 71 .endm 72 73 /* 74 * kernel_ok determines whether we should bypass addr/size checking. 75 * See the equivalent C-macro version below for clarity. 76 * On success, kernel_ok branches to a label indicated by parameter 77 * <success>. This implies that the macro falls through to the next 78 * insruction on an error. 79 * 80 * Note that while this macro can be used independently, we designed 81 * in for optimal use in the access_ok macro below (i.e., we fall 82 * through on error). 83 * 84 * On Entry: 85 * <at> anything (temp register) 86 * <success> label to branch to on success; implies 87 * fall-through macro on error 88 * <sp> stack pointer 89 * On Exit: 90 * <at> destroyed (actually, current->thread.current_ds) 91 */ 92 93 #if ((KERNEL_DS != 0) || (USER_DS == 0)) 94 # error Assembly macro kernel_ok fails 95 #endif 96 .macro kernel_ok at, sp, success 97 get_fs \at, \sp 98 beqz \at, \success 99 .endm 100 101 /* 102 * user_ok determines whether the access to user-space memory is allowed. 103 * See the equivalent C-macro version below for clarity. 104 * 105 * On error, user_ok branches to a label indicated by parameter 106 * <error>. This implies that the macro falls through to the next 107 * instruction on success. 108 * 109 * Note that while this macro can be used independently, we designed 110 * in for optimal use in the access_ok macro below (i.e., we fall 111 * through on success). 112 * 113 * On Entry: 114 * <aa> register containing memory address 115 * <as> register containing memory size 116 * <at> temp register 117 * <error> label to branch to on error; implies fall-through 118 * macro on success 119 * On Exit: 120 * <aa> preserved 121 * <as> preserved 122 * <at> destroyed (actually, (TASK_SIZE + 1 - size)) 123 */ 124 .macro user_ok aa, as, at, error 125 movi \at, __XTENSA_UL_CONST(TASK_SIZE) 126 bgeu \as, \at, \error 127 sub \at, \at, \as 128 bgeu \aa, \at, \error 129 .endm 130 131 /* 132 * access_ok determines whether a memory access is allowed. See the 133 * equivalent C-macro version below for clarity. 134 * 135 * On error, access_ok branches to a label indicated by parameter 136 * <error>. This implies that the macro falls through to the next 137 * instruction on success. 138 * 139 * Note that we assume success is the common case, and we optimize the 140 * branch fall-through case on success. 141 * 142 * On Entry: 143 * <aa> register containing memory address 144 * <as> register containing memory size 145 * <at> temp register 146 * <sp> 147 * <error> label to branch to on error; implies fall-through 148 * macro on success 149 * On Exit: 150 * <aa> preserved 151 * <as> preserved 152 * <at> destroyed 153 */ 154 .macro access_ok aa, as, at, sp, error 155 kernel_ok \at, \sp, .Laccess_ok_\@ 156 user_ok \aa, \as, \at, \error 157 .Laccess_ok_\@: 158 .endm 159 160 #endif /* _XTENSA_ASM_UACCESS_H */ 161