| 1 | |
| 2 | * include/asm-xtensa/uaccess.h
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| 3 | *
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| 4 | * User space memory access functions
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| 5 | *
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| 6 | * These routines provide basic accessing functions to the user memory
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| 7 | * space for the kernel. This header file provides functions such as:
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| 8 | *
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| 9 | * This file is subject to the terms and conditions of the GNU General Public
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| 10 | * License. See the file "COPYING" in the main directory of this archive
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| 11 | * for more details.
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| 12 | *
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| 13 | * Copyright (C) 2001 - 2005 Tensilica Inc.
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| 14 |
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| 15 |
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| 16 | #ifndef _XTENSA_ASM_UACCESS_H
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| 17 | #define _XTENSA_ASM_UACCESS_H
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| 18 |
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| 19 | #include <linux/errno.h>
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| 20 | #include <asm/types.h>
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| 21 |
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| 22 | #include <asm/current.h>
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| 23 | #include <asm/asm-offsets.h>
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| 24 | #include <asm/processor.h>
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| 25 |
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| 26 | |
| 27 | * user_ok determines whether the access to user-space memory is allowed.
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| 28 | * See the equivalent C-macro version below for clarity.
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| 29 | *
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| 30 | * On error, user_ok branches to a label indicated by parameter
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| 31 | * <error>. This implies that the macro falls through to the next
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| 32 | * instruction on success.
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| 33 | *
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| 34 | * Note that while this macro can be used independently, we designed
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| 35 | * in for optimal use in the access_ok macro below (i.e., we fall
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| 36 | * through on success).
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| 37 | *
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| 38 | * On Entry:
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| 39 | * <aa> register containing memory address
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| 40 | * <as> register containing memory size
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| 41 | * <at> temp register
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| 42 | * <error> label to branch to on error; implies fall-through
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| 43 | * macro on success
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| 44 | * On Exit:
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| 45 | * <aa> preserved
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| 46 | * <as> preserved
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| 47 | * <at> destroyed (actually, (TASK_SIZE + 1 - size))
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| 48 |
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| 49 | .macro user_ok aa, as, at, error
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| 50 | movi \at, __XTENSA_UL_CONST(TASK_SIZE)
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| 51 | bgeu \as, \at, \error
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| 52 | sub \at, \at, \as
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| 53 | bgeu \aa, \at, \error
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| 54 | .endm
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| 55 |
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| 56 | |
| 57 | * access_ok determines whether a memory access is allowed. See the
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| 58 | * equivalent C-macro version below for clarity.
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| 59 | *
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| 60 | * On error, access_ok branches to a label indicated by parameter
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| 61 | * <error>. This implies that the macro falls through to the next
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| 62 | * instruction on success.
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| 63 | *
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| 64 | * Note that we assume success is the common case, and we optimize the
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| 65 | * branch fall-through case on success.
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| 66 | *
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| 67 | * On Entry:
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| 68 | * <aa> register containing memory address
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| 69 | * <as> register containing memory size
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| 70 | * <at> temp register
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| 71 | * <sp>
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| 72 | * <error> label to branch to on error; implies fall-through
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| 73 | * macro on success
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| 74 | * On Exit:
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| 75 | * <aa> preserved
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| 76 | * <as> preserved
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| 77 | * <at> destroyed
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| 78 |
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| 79 | .macro access_ok aa, as, at, sp, error
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| 80 | user_ok \aa, \as, \at, \error
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| 81 | .Laccess_ok_\@:
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| 82 | .endm
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| 83 |
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| 84 | #endif
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