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155 lines
4.1 KiB
155 lines
4.1 KiB
/* |
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* include/asm-xtensa/uaccess.h |
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* |
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* User space memory access functions |
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* |
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* These routines provide basic accessing functions to the user memory |
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* space for the kernel. This header file provides functions such as: |
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* |
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* This file is subject to the terms and conditions of the GNU General Public |
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* License. See the file "COPYING" in the main directory of this archive |
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* for more details. |
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* |
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* Copyright (C) 2001 - 2005 Tensilica Inc. |
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*/ |
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#ifndef _XTENSA_ASM_UACCESS_H |
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#define _XTENSA_ASM_UACCESS_H |
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#include <linux/errno.h> |
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#include <asm/types.h> |
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#include <asm/current.h> |
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#include <asm/asm-offsets.h> |
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#include <asm/processor.h> |
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/* |
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* These assembly macros mirror the C macros in asm/uaccess.h. They |
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* should always have identical functionality. See |
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* arch/xtensa/kernel/sys.S for usage. |
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*/ |
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#define KERNEL_DS 0 |
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#define USER_DS 1 |
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/* |
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* get_fs reads current->thread.current_ds into a register. |
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* On Entry: |
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* <ad> anything |
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* <sp> stack |
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* On Exit: |
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* <ad> contains current->thread.current_ds |
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*/ |
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.macro get_fs ad, sp |
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GET_CURRENT(\ad,\sp) |
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#if THREAD_CURRENT_DS > 1020 |
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addi \ad, \ad, TASK_THREAD |
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l32i \ad, \ad, THREAD_CURRENT_DS - TASK_THREAD |
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#else |
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l32i \ad, \ad, THREAD_CURRENT_DS |
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#endif |
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.endm |
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/* |
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* set_fs sets current->thread.current_ds to some value. |
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* On Entry: |
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* <at> anything (temp register) |
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* <av> value to write |
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* <sp> stack |
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* On Exit: |
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* <at> destroyed (actually, current) |
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* <av> preserved, value to write |
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*/ |
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.macro set_fs at, av, sp |
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GET_CURRENT(\at,\sp) |
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s32i \av, \at, THREAD_CURRENT_DS |
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.endm |
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/* |
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* kernel_ok determines whether we should bypass addr/size checking. |
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* See the equivalent C-macro version below for clarity. |
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* On success, kernel_ok branches to a label indicated by parameter |
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* <success>. This implies that the macro falls through to the next |
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* insruction on an error. |
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* |
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* Note that while this macro can be used independently, we designed |
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* in for optimal use in the access_ok macro below (i.e., we fall |
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* through on error). |
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* |
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* On Entry: |
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* <at> anything (temp register) |
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* <success> label to branch to on success; implies |
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* fall-through macro on error |
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* <sp> stack pointer |
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* On Exit: |
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* <at> destroyed (actually, current->thread.current_ds) |
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*/ |
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#if ((KERNEL_DS != 0) || (USER_DS == 0)) |
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# error Assembly macro kernel_ok fails |
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#endif |
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.macro kernel_ok at, sp, success |
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get_fs \at, \sp |
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beqz \at, \success |
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.endm |
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/* |
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* user_ok determines whether the access to user-space memory is allowed. |
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* See the equivalent C-macro version below for clarity. |
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* |
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* On error, user_ok branches to a label indicated by parameter |
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* <error>. This implies that the macro falls through to the next |
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* instruction on success. |
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* |
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* Note that while this macro can be used independently, we designed |
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* in for optimal use in the access_ok macro below (i.e., we fall |
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* through on success). |
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* |
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* On Entry: |
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* <aa> register containing memory address |
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* <as> register containing memory size |
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* <at> temp register |
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* <error> label to branch to on error; implies fall-through |
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* macro on success |
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* On Exit: |
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* <aa> preserved |
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* <as> preserved |
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* <at> destroyed (actually, (TASK_SIZE + 1 - size)) |
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*/ |
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.macro user_ok aa, as, at, error |
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movi \at, __XTENSA_UL_CONST(TASK_SIZE) |
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bgeu \as, \at, \error |
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sub \at, \at, \as |
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bgeu \aa, \at, \error |
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.endm |
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/* |
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* access_ok determines whether a memory access is allowed. See the |
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* equivalent C-macro version below for clarity. |
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* |
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* On error, access_ok branches to a label indicated by parameter |
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* <error>. This implies that the macro falls through to the next |
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* instruction on success. |
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* |
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* Note that we assume success is the common case, and we optimize the |
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* branch fall-through case on success. |
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* |
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* On Entry: |
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* <aa> register containing memory address |
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* <as> register containing memory size |
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* <at> temp register |
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* <sp> |
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* <error> label to branch to on error; implies fall-through |
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* macro on success |
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* On Exit: |
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* <aa> preserved |
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* <as> preserved |
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* <at> destroyed |
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*/ |
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.macro access_ok aa, as, at, sp, error |
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kernel_ok \at, \sp, .Laccess_ok_\@ |
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user_ok \aa, \as, \at, \error |
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.Laccess_ok_\@: |
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.endm |
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#endif /* _XTENSA_ASM_UACCESS_H */
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