| Andrew Scull | b4b6d4a | 2019-01-02 15:54:55 +0000 | [diff] [blame] | 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 | |
| Andrew Scull | b4b6d4a | 2019-01-02 15:54:55 +0000 | [diff] [blame] | 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 */ |