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+/*
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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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+
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+#ifndef _XTENSA_ASM_UACCESS_H
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+#define _XTENSA_ASM_UACCESS_H
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+
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+#include <linux/errno.h>
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+#include <asm/types.h>
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+
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+#define VERIFY_READ 0
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+#define VERIFY_WRITE 1
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+
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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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+/*
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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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+
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+#define KERNEL_DS 0
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+#define USER_DS 1
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+
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+#define get_ds (KERNEL_DS)
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+
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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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+/*
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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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+/*
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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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+
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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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+/*
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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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+/*
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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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+
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+#endif /* _XTENSA_ASM_UACCESS_H */
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Al Viro