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1/*
2 * Debug Store (DS) support
3 *
4 * This provides a low-level interface to the hardware's Debug Store
5 * feature that is used for branch trace store (BTS) and
6 * precise-event based sampling (PEBS).
7 *
8 * It manages:
9 * - per-thread and per-cpu allocation of BTS and PEBS
10 * - buffer memory allocation (optional)
11 * - buffer overflow handling
12 * - buffer access
13 *
14 * It assumes:
15 * - get_task_struct on all parameter tasks
16 * - current is allowed to trace parameter tasks
17 *
18 *
19 * Copyright (C) 2007-2008 Intel Corporation.
20 * Markus Metzger <markus.t.metzger@intel.com>, 2007-2008
21 */
22
23#ifndef _ASM_X86_DS_H
24#define _ASM_X86_DS_H
25
26#ifdef CONFIG_X86_DS
27
28#include <linux/types.h>
29#include <linux/init.h>
30
31
32struct task_struct;
33
34/*
35 * Request BTS or PEBS
36 *
37 * Due to alignement constraints, the actual buffer may be slightly
38 * smaller than the requested or provided buffer.
39 *
40 * Returns 0 on success; -Eerrno otherwise
41 *
42 * task: the task to request recording for;
43 * NULL for per-cpu recording on the current cpu
44 * base: the base pointer for the (non-pageable) buffer;
45 * NULL if buffer allocation requested
46 * size: the size of the requested or provided buffer
47 * ovfl: pointer to a function to be called on buffer overflow;
48 * NULL if cyclic buffer requested
49 */
50typedef void (*ds_ovfl_callback_t)(struct task_struct *);
51extern int ds_request_bts(struct task_struct *task, void *base, size_t size,
52 ds_ovfl_callback_t ovfl);
53extern int ds_request_pebs(struct task_struct *task, void *base, size_t size,
54 ds_ovfl_callback_t ovfl);
55
56/*
57 * Release BTS or PEBS resources
58 *
59 * Frees buffers allocated on ds_request.
60 *
61 * Returns 0 on success; -Eerrno otherwise
62 *
63 * task: the task to release resources for;
64 * NULL to release resources for the current cpu
65 */
66extern int ds_release_bts(struct task_struct *task);
67extern int ds_release_pebs(struct task_struct *task);
68
69/*
70 * Return the (array) index of the write pointer.
71 * (assuming an array of BTS/PEBS records)
72 *
73 * Returns -Eerrno on error
74 *
75 * task: the task to access;
76 * NULL to access the current cpu
77 * pos (out): if not NULL, will hold the result
78 */
79extern int ds_get_bts_index(struct task_struct *task, size_t *pos);
80extern int ds_get_pebs_index(struct task_struct *task, size_t *pos);
81
82/*
83 * Return the (array) index one record beyond the end of the array.
84 * (assuming an array of BTS/PEBS records)
85 *
86 * Returns -Eerrno on error
87 *
88 * task: the task to access;
89 * NULL to access the current cpu
90 * pos (out): if not NULL, will hold the result
91 */
92extern int ds_get_bts_end(struct task_struct *task, size_t *pos);
93extern int ds_get_pebs_end(struct task_struct *task, size_t *pos);
94
95/*
96 * Provide a pointer to the BTS/PEBS record at parameter index.
97 * (assuming an array of BTS/PEBS records)
98 *
99 * The pointer points directly into the buffer. The user is
100 * responsible for copying the record.
101 *
102 * Returns the size of a single record on success; -Eerrno on error
103 *
104 * task: the task to access;
105 * NULL to access the current cpu
106 * index: the index of the requested record
107 * record (out): pointer to the requested record
108 */
109extern int ds_access_bts(struct task_struct *task,
110 size_t index, const void **record);
111extern int ds_access_pebs(struct task_struct *task,
112 size_t index, const void **record);
113
114/*
115 * Write one or more BTS/PEBS records at the write pointer index and
116 * advance the write pointer.
117 *
118 * If size is not a multiple of the record size, trailing bytes are
119 * zeroed out.
120 *
121 * May result in one or more overflow notifications.
122 *
123 * If called during overflow handling, that is, with index >=
124 * interrupt threshold, the write will wrap around.
125 *
126 * An overflow notification is given if and when the interrupt
127 * threshold is reached during or after the write.
128 *
129 * Returns the number of bytes written or -Eerrno.
130 *
131 * task: the task to access;
132 * NULL to access the current cpu
133 * buffer: the buffer to write
134 * size: the size of the buffer
135 */
136extern int ds_write_bts(struct task_struct *task,
137 const void *buffer, size_t size);
138extern int ds_write_pebs(struct task_struct *task,
139 const void *buffer, size_t size);
140
141/*
142 * Same as ds_write_bts/pebs, but omit ownership checks.
143 *
144 * This is needed to have some other task than the owner of the
145 * BTS/PEBS buffer or the parameter task itself write into the
146 * respective buffer.
147 */
148extern int ds_unchecked_write_bts(struct task_struct *task,
149 const void *buffer, size_t size);
150extern int ds_unchecked_write_pebs(struct task_struct *task,
151 const void *buffer, size_t size);
152
153/*
154 * Reset the write pointer of the BTS/PEBS buffer.
155 *
156 * Returns 0 on success; -Eerrno on error
157 *
158 * task: the task to access;
159 * NULL to access the current cpu
160 */
161extern int ds_reset_bts(struct task_struct *task);
162extern int ds_reset_pebs(struct task_struct *task);
163
164/*
165 * Clear the BTS/PEBS buffer and reset the write pointer.
166 * The entire buffer will be zeroed out.
167 *
168 * Returns 0 on success; -Eerrno on error
169 *
170 * task: the task to access;
171 * NULL to access the current cpu
172 */
173extern int ds_clear_bts(struct task_struct *task);
174extern int ds_clear_pebs(struct task_struct *task);
175
176/*
177 * Provide the PEBS counter reset value.
178 *
179 * Returns 0 on success; -Eerrno on error
180 *
181 * task: the task to access;
182 * NULL to access the current cpu
183 * value (out): the counter reset value
184 */
185extern int ds_get_pebs_reset(struct task_struct *task, u64 *value);
186
187/*
188 * Set the PEBS counter reset value.
189 *
190 * Returns 0 on success; -Eerrno on error
191 *
192 * task: the task to access;
193 * NULL to access the current cpu
194 * value: the new counter reset value
195 */
196extern int ds_set_pebs_reset(struct task_struct *task, u64 value);
197
198/*
199 * Initialization
200 */
201struct cpuinfo_x86;
202extern void __cpuinit ds_init_intel(struct cpuinfo_x86 *);
203
204
205
206/*
207 * The DS context - part of struct thread_struct.
208 */
209struct ds_context {
210 /* pointer to the DS configuration; goes into MSR_IA32_DS_AREA */
211 unsigned char *ds;
212 /* the owner of the BTS and PEBS configuration, respectively */
213 struct task_struct *owner[2];
214 /* buffer overflow notification function for BTS and PEBS */
215 ds_ovfl_callback_t callback[2];
216 /* the original buffer address */
217 void *buffer[2];
218 /* the number of allocated pages for on-request allocated buffers */
219 unsigned int pages[2];
220 /* use count */
221 unsigned long count;
222 /* a pointer to the context location inside the thread_struct
223 * or the per_cpu context array */
224 struct ds_context **this;
225 /* a pointer to the task owning this context, or NULL, if the
226 * context is owned by a cpu */
227 struct task_struct *task;
228};
229
230/* called by exit_thread() to free leftover contexts */
231extern void ds_free(struct ds_context *context);
232
233#else /* CONFIG_X86_DS */
234
235#define ds_init_intel(config) do {} while (0)
236
237#endif /* CONFIG_X86_DS */
238#endif /* _ASM_X86_DS_H */
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