| 1 | |
| 2 | * User-mode machine state access
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| 3 | *
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| 4 | * Copyright (C) 2007 Red Hat, Inc. All rights reserved.
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| 5 | *
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| 6 | * This copyrighted material is made available to anyone wishing to use,
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| 7 | * modify, copy, or redistribute it subject to the terms and conditions
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| 8 | * of the GNU General Public License v.2.
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| 9 | *
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| 10 | * Red Hat Author: Roland McGrath.
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| 11 |
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| 12 |
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| 13 | #ifndef _LINUX_REGSET_H
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| 14 | #define _LINUX_REGSET_H 1
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| 15 |
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| 16 | #include <linux/compiler.h>
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| 17 | #include <linux/types.h>
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| 18 | #include <linux/uaccess.h>
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| 19 | struct task_struct;
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| 20 | struct user_regset;
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| 21 |
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| 22 |
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| 23 | |
| 24 | * user_regset_active_fn - type of @active function in &struct user_regset
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| 25 | * @target: thread being examined
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| 26 | * @regset: regset being examined
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| 27 | *
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| 28 | * Return -%ENODEV if not available on the hardware found.
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| 29 | * Return %0 if no interesting state in this thread.
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| 30 | * Return >%0 number of @size units of interesting state.
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| 31 | * Any get call fetching state beyond that number will
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| 32 | * see the default initialization state for this data,
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| 33 | * so a caller that knows what the default state is need
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| 34 | * not copy it all out.
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| 35 | * This call is optional; the pointer is %NULL if there
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| 36 | * is no inexpensive check to yield a value < @n.
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| 37 |
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| 38 | typedef int user_regset_active_fn(struct task_struct *target,
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| 39 | const struct user_regset *regset);
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| 40 |
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| 41 | |
| 42 | * user_regset_get_fn - type of @get function in &struct user_regset
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| 43 | * @target: thread being examined
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| 44 | * @regset: regset being examined
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| 45 | * @pos: offset into the regset data to access, in bytes
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| 46 | * @count: amount of data to copy, in bytes
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| 47 | * @kbuf: if not %NULL, a kernel-space pointer to copy into
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| 48 | * @ubuf: if @kbuf is %NULL, a user-space pointer to copy into
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| 49 | *
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| 50 | * Fetch register values. Return %0 on success; -%EIO or -%ENODEV
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| 51 | * are usual failure returns. The @pos and @count values are in
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| 52 | * bytes, but must be properly aligned. If @kbuf is non-null, that
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| 53 | * buffer is used and @ubuf is ignored. If @kbuf is %NULL, then
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| 54 | * ubuf gives a userland pointer to access directly, and an -%EFAULT
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| 55 | * return value is possible.
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| 56 |
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| 57 | typedef int user_regset_get_fn(struct task_struct *target,
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| 58 | const struct user_regset *regset,
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| 59 | unsigned int pos, unsigned int count,
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| 60 | void *kbuf, void __user *ubuf);
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| 61 |
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| 62 | |
| 63 | * user_regset_set_fn - type of @set function in &struct user_regset
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| 64 | * @target: thread being examined
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| 65 | * @regset: regset being examined
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| 66 | * @pos: offset into the regset data to access, in bytes
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| 67 | * @count: amount of data to copy, in bytes
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| 68 | * @kbuf: if not %NULL, a kernel-space pointer to copy from
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| 69 | * @ubuf: if @kbuf is %NULL, a user-space pointer to copy from
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| 70 | *
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| 71 | * Store register values. Return %0 on success; -%EIO or -%ENODEV
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| 72 | * are usual failure returns. The @pos and @count values are in
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| 73 | * bytes, but must be properly aligned. If @kbuf is non-null, that
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| 74 | * buffer is used and @ubuf is ignored. If @kbuf is %NULL, then
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| 75 | * ubuf gives a userland pointer to access directly, and an -%EFAULT
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| 76 | * return value is possible.
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| 77 |
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| 78 | typedef int user_regset_set_fn(struct task_struct *target,
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| 79 | const struct user_regset *regset,
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| 80 | unsigned int pos, unsigned int count,
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| 81 | const void *kbuf, const void __user *ubuf);
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| 82 |
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| 83 | |
| 84 | * user_regset_writeback_fn - type of @writeback function in &struct user_regset
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| 85 | * @target: thread being examined
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| 86 | * @regset: regset being examined
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| 87 | * @immediate: zero if writeback at completion of next context switch is OK
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| 88 | *
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| 89 | * This call is optional; usually the pointer is %NULL. When
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| 90 | * provided, there is some user memory associated with this regset's
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| 91 | * hardware, such as memory backing cached register data on register
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| 92 | * window machines; the regset's data controls what user memory is
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| 93 | * used (e.g. via the stack pointer value).
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| 94 | *
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| 95 | * Write register data back to user memory. If the @immediate flag
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| 96 | * is nonzero, it must be written to the user memory so uaccess or
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| 97 | * access_process_vm() can see it when this call returns; if zero,
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| 98 | * then it must be written back by the time the task completes a
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| 99 | * context switch (as synchronized with wait_task_inactive()).
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| 100 | * Return %0 on success or if there was nothing to do, -%EFAULT for
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| 101 | * a memory problem (bad stack pointer or whatever), or -%EIO for a
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| 102 | * hardware problem.
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| 103 |
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| 104 | typedef int user_regset_writeback_fn(struct task_struct *target,
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| 105 | const struct user_regset *regset,
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| 106 | int immediate);
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| 107 |
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| 108 | |
| 109 | * struct user_regset - accessible thread CPU state
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| 110 | * @n: Number of slots (registers).
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| 111 | * @size: Size in bytes of a slot (register).
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| 112 | * @align: Required alignment, in bytes.
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| 113 | * @bias: Bias from natural indexing.
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| 114 | * @core_note_type: ELF note @n_type value used in core dumps.
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| 115 | * @get: Function to fetch values.
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| 116 | * @set: Function to store values.
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| 117 | * @active: Function to report if regset is active, or %NULL.
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| 118 | * @writeback: Function to write data back to user memory, or %NULL.
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| 119 | *
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| 120 | * This data structure describes a machine resource we call a register set.
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| 121 | * This is part of the state of an individual thread, not necessarily
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| 122 | * actual CPU registers per se. A register set consists of a number of
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| 123 | * similar slots, given by @n. Each slot is @size bytes, and aligned to
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| 124 | * @align bytes (which is at least @size).
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| 125 | *
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| 126 | * These functions must be called only on the current thread or on a
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| 127 | * thread that is in %TASK_STOPPED or %TASK_TRACED state, that we are
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| 128 | * guaranteed will not be woken up and return to user mode, and that we
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| 129 | * have called wait_task_inactive() on. (The target thread always might
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| 130 | * wake up for SIGKILL while these functions are working, in which case
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| 131 | * that thread's user_regset state might be scrambled.)
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| 132 | *
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| 133 | * The @pos argument must be aligned according to @align; the @count
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| 134 | * argument must be a multiple of @size. These functions are not
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| 135 | * responsible for checking for invalid arguments.
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| 136 | *
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| 137 | * When there is a natural value to use as an index, @bias gives the
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| 138 | * difference between the natural index and the slot index for the
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| 139 | * register set. For example, x86 GDT segment descriptors form a regset;
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| 140 | * the segment selector produces a natural index, but only a subset of
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| 141 | * that index space is available as a regset (the TLS slots); subtracting
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| 142 | * @bias from a segment selector index value computes the regset slot.
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| 143 | *
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| 144 | * If nonzero, @core_note_type gives the n_type field (NT_* value)
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| 145 | * of the core file note in which this regset's data appears.
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| 146 | * NT_PRSTATUS is a special case in that the regset data starts at
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| 147 | * offsetof(struct elf_prstatus, pr_reg) into the note data; that is
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| 148 | * part of the per-machine ELF formats userland knows about. In
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| 149 | * other cases, the core file note contains exactly the whole regset
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| 150 | * (@n * @size) and nothing else. The core file note is normally
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| 151 | * omitted when there is an @active function and it returns zero.
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| 152 |
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| 153 | struct user_regset {
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| 154 | user_regset_get_fn *get;
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| 155 | user_regset_set_fn *set;
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| 156 | user_regset_active_fn *active;
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| 157 | user_regset_writeback_fn *writeback;
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| 158 | unsigned int n;
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| 159 | unsigned int size;
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| 160 | unsigned int align;
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| 161 | unsigned int bias;
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| 162 | unsigned int core_note_type;
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| 163 | };
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| 164 |
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| 165 | |
| 166 | * struct user_regset_view - available regsets
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| 167 | * @name: Identifier, e.g. UTS_MACHINE string.
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| 168 | * @regsets: Array of @n regsets available in this view.
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| 169 | * @n: Number of elements in @regsets.
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| 170 | * @e_machine: ELF header @e_machine %EM_* value written in core dumps.
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| 171 | * @e_flags: ELF header @e_flags value written in core dumps.
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| 172 | * @ei_osabi: ELF header @e_ident[%EI_OSABI] value written in core dumps.
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| 173 | *
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| 174 | * A regset view is a collection of regsets (&struct user_regset,
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| 175 | * above). This describes all the state of a thread that can be seen
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| 176 | * from a given architecture/ABI environment. More than one view might
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| 177 | * refer to the same &struct user_regset, or more than one regset
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| 178 | * might refer to the same machine-specific state in the thread. For
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| 179 | * example, a 32-bit thread's state could be examined from the 32-bit
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| 180 | * view or from the 64-bit view. Either method reaches the same thread
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| 181 | * register state, doing appropriate widening or truncation.
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| 182 |
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| 183 | struct user_regset_view {
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| 184 | const char *name;
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| 185 | const struct user_regset *regsets;
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| 186 | unsigned int n;
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| 187 | u32 e_flags;
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| 188 | u16 e_machine;
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| 189 | u8 ei_osabi;
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| 190 | };
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| 191 |
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| 192 | |
| 193 | * This is documented here rather than at the definition sites because its
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| 194 | * implementation is machine-dependent but its interface is universal.
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| 195 |
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| 196 | |
| 197 | * task_user_regset_view - Return the process's native regset view.
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| 198 | * @tsk: a thread of the process in question
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| 199 | *
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| 200 | * Return the &struct user_regset_view that is native for the given process.
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| 201 | * For example, what it would access when it called ptrace().
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| 202 | * Throughout the life of the process, this only changes at exec.
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| 203 |
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| 204 | const struct user_regset_view *task_user_regset_view(struct task_struct *tsk);
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| 205 |
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| 206 |
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| 207 | |
| 208 | * These are helpers for writing regset get/set functions in arch code.
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| 209 | * Because @start_pos and @end_pos are always compile-time constants,
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| 210 | * these are inlined into very little code though they look large.
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| 211 | *
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| 212 | * Use one or more calls sequentially for each chunk of regset data stored
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| 213 | * contiguously in memory. Call with constants for @start_pos and @end_pos,
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| 214 | * giving the range of byte positions in the regset that data corresponds
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| 215 | * to; @end_pos can be -1 if this chunk is at the end of the regset layout.
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| 216 | * Each call updates the arguments to point past its chunk.
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| 217 |
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| 218 |
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| 219 | static inline int user_regset_copyout(unsigned int *pos, unsigned int *count,
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| 220 | void **kbuf,
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| 221 | void __user **ubuf, const void *data,
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| 222 | const int start_pos, const int end_pos)
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| 223 | {
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| 224 | if (*count == 0)
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| 225 | return 0;
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| 226 | BUG_ON(*pos < start_pos);
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| 227 | if (end_pos < 0 || *pos < end_pos) {
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| 228 | unsigned int copy = (end_pos < 0 ? *count
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| 229 | : min(*count, end_pos - *pos));
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| 230 | data += *pos - start_pos;
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| 231 | if (*kbuf) {
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| 232 | memcpy(*kbuf, data, copy);
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| 233 | *kbuf += copy;
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| 234 | } else if (__copy_to_user(*ubuf, data, copy))
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| 235 | return -EFAULT;
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| 236 | else
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| 237 | *ubuf += copy;
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| 238 | *pos += copy;
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| 239 | *count -= copy;
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| 240 | }
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| 241 | return 0;
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| 242 | }
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| 243 |
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| 244 | static inline int user_regset_copyin(unsigned int *pos, unsigned int *count,
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| 245 | const void **kbuf,
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| 246 | const void __user **ubuf, void *data,
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| 247 | const int start_pos, const int end_pos)
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| 248 | {
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| 249 | if (*count == 0)
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| 250 | return 0;
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| 251 | BUG_ON(*pos < start_pos);
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| 252 | if (end_pos < 0 || *pos < end_pos) {
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| 253 | unsigned int copy = (end_pos < 0 ? *count
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| 254 | : min(*count, end_pos - *pos));
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| 255 | data += *pos - start_pos;
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| 256 | if (*kbuf) {
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| 257 | memcpy(data, *kbuf, copy);
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| 258 | *kbuf += copy;
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| 259 | } else if (__copy_from_user(data, *ubuf, copy))
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| 260 | return -EFAULT;
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| 261 | else
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| 262 | *ubuf += copy;
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| 263 | *pos += copy;
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| 264 | *count -= copy;
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| 265 | }
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| 266 | return 0;
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| 267 | }
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| 268 |
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| 269 | |
| 270 | * These two parallel the two above, but for portions of a regset layout
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| 271 | * that always read as all-zero or for which writes are ignored.
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| 272 |
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| 273 | static inline int user_regset_copyout_zero(unsigned int *pos,
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| 274 | unsigned int *count,
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| 275 | void **kbuf, void __user **ubuf,
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| 276 | const int start_pos,
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| 277 | const int end_pos)
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| 278 | {
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| 279 | if (*count == 0)
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| 280 | return 0;
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| 281 | BUG_ON(*pos < start_pos);
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| 282 | if (end_pos < 0 || *pos < end_pos) {
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| 283 | unsigned int copy = (end_pos < 0 ? *count
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| 284 | : min(*count, end_pos - *pos));
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| 285 | if (*kbuf) {
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| 286 | memset(*kbuf, 0, copy);
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| 287 | *kbuf += copy;
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| 288 | } else if (__clear_user(*ubuf, copy))
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| 289 | return -EFAULT;
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| 290 | else
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| 291 | *ubuf += copy;
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| 292 | *pos += copy;
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| 293 | *count -= copy;
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| 294 | }
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| 295 | return 0;
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| 296 | }
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| 297 |
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| 298 | static inline int user_regset_copyin_ignore(unsigned int *pos,
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| 299 | unsigned int *count,
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| 300 | const void **kbuf,
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| 301 | const void __user **ubuf,
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| 302 | const int start_pos,
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| 303 | const int end_pos)
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| 304 | {
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| 305 | if (*count == 0)
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| 306 | return 0;
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| 307 | BUG_ON(*pos < start_pos);
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| 308 | if (end_pos < 0 || *pos < end_pos) {
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| 309 | unsigned int copy = (end_pos < 0 ? *count
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| 310 | : min(*count, end_pos - *pos));
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| 311 | if (*kbuf)
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| 312 | *kbuf += copy;
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| 313 | else
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| 314 | *ubuf += copy;
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| 315 | *pos += copy;
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| 316 | *count -= copy;
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| 317 | }
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| 318 | return 0;
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| 319 | }
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| 320 |
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| 321 | |
| 322 | * copy_regset_to_user - fetch a thread's user_regset data into user memory
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| 323 | * @target: thread to be examined
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| 324 | * @view: &struct user_regset_view describing user thread machine state
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| 325 | * @setno: index in @view->regsets
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| 326 | * @offset: offset into the regset data, in bytes
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| 327 | * @size: amount of data to copy, in bytes
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| 328 | * @data: user-mode pointer to copy into
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| 329 |
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| 330 | static inline int copy_regset_to_user(struct task_struct *target,
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| 331 | const struct user_regset_view *view,
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| 332 | unsigned int setno,
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| 333 | unsigned int offset, unsigned int size,
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| 334 | void __user *data)
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| 335 | {
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| 336 | const struct user_regset *regset = &view->regsets[setno];
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| 337 |
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| 338 | if (!access_ok(VERIFY_WRITE, data, size))
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| 339 | return -EIO;
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| 340 |
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| 341 | return regset->get(target, regset, offset, size, NULL, data);
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| 342 | }
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| 343 |
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| 344 | |
| 345 | * copy_regset_from_user - store into thread's user_regset data from user memory
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| 346 | * @target: thread to be examined
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| 347 | * @view: &struct user_regset_view describing user thread machine state
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| 348 | * @setno: index in @view->regsets
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| 349 | * @offset: offset into the regset data, in bytes
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| 350 | * @size: amount of data to copy, in bytes
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| 351 | * @data: user-mode pointer to copy from
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| 352 |
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| 353 | static inline int copy_regset_from_user(struct task_struct *target,
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| 354 | const struct user_regset_view *view,
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| 355 | unsigned int setno,
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| 356 | unsigned int offset, unsigned int size,
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| 357 | const void __user *data)
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| 358 | {
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| 359 | const struct user_regset *regset = &view->regsets[setno];
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| 360 |
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| 361 | if (!access_ok(VERIFY_READ, data, size))
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| 362 | return -EIO;
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| 363 |
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| 364 | return regset->set(target, regset, offset, size, NULL, data);
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| 365 | }
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| 366 |
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| 367 |
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| 368 | #endif
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