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 /* 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 */ 156