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