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1da177e4 LT |
1 | /** |
2 | * @file cpu_buffer.c | |
3 | * | |
4 | * @remark Copyright 2002 OProfile authors | |
5 | * @remark Read the file COPYING | |
6 | * | |
7 | * @author John Levon <levon@movementarian.org> | |
345c2573 | 8 | * @author Barry Kasindorf <barry.kasindorf@amd.com> |
1da177e4 LT |
9 | * |
10 | * Each CPU has a local buffer that stores PC value/event | |
11 | * pairs. We also log context switches when we notice them. | |
12 | * Eventually each CPU's buffer is processed into the global | |
13 | * event buffer by sync_buffer(). | |
14 | * | |
15 | * We use a local buffer for two reasons: an NMI or similar | |
16 | * interrupt cannot synchronise, and high sampling rates | |
17 | * would lead to catastrophic global synchronisation if | |
18 | * a global buffer was used. | |
19 | */ | |
20 | ||
21 | #include <linux/sched.h> | |
22 | #include <linux/oprofile.h> | |
23 | #include <linux/vmalloc.h> | |
24 | #include <linux/errno.h> | |
6a18037d | 25 | |
1da177e4 LT |
26 | #include "event_buffer.h" |
27 | #include "cpu_buffer.h" | |
28 | #include "buffer_sync.h" | |
29 | #include "oprof.h" | |
30 | ||
8b8b4988 | 31 | DEFINE_PER_CPU(struct oprofile_cpu_buffer, cpu_buffer); |
1da177e4 | 32 | |
c4028958 | 33 | static void wq_sync_buffer(struct work_struct *work); |
1da177e4 LT |
34 | |
35 | #define DEFAULT_TIMER_EXPIRE (HZ / 10) | |
36 | static int work_enabled; | |
37 | ||
38 | void free_cpu_buffers(void) | |
39 | { | |
40 | int i; | |
6a18037d | 41 | |
f4156d1c | 42 | for_each_online_cpu(i) { |
608dfddd | 43 | vfree(per_cpu(cpu_buffer, i).buffer); |
f4156d1c CL |
44 | per_cpu(cpu_buffer, i).buffer = NULL; |
45 | } | |
1da177e4 | 46 | } |
77933d72 | 47 | |
1da177e4 LT |
48 | int alloc_cpu_buffers(void) |
49 | { | |
50 | int i; | |
6a18037d | 51 | |
1da177e4 | 52 | unsigned long buffer_size = fs_cpu_buffer_size; |
6a18037d | 53 | |
1da177e4 | 54 | for_each_online_cpu(i) { |
608dfddd | 55 | struct oprofile_cpu_buffer *b = &per_cpu(cpu_buffer, i); |
6a18037d | 56 | |
25ab7cd8 ED |
57 | b->buffer = vmalloc_node(sizeof(struct op_sample) * buffer_size, |
58 | cpu_to_node(i)); | |
1da177e4 LT |
59 | if (!b->buffer) |
60 | goto fail; | |
6a18037d | 61 | |
1da177e4 LT |
62 | b->last_task = NULL; |
63 | b->last_is_kernel = -1; | |
64 | b->tracing = 0; | |
65 | b->buffer_size = buffer_size; | |
66 | b->tail_pos = 0; | |
67 | b->head_pos = 0; | |
68 | b->sample_received = 0; | |
69 | b->sample_lost_overflow = 0; | |
df9d177a PE |
70 | b->backtrace_aborted = 0; |
71 | b->sample_invalid_eip = 0; | |
1da177e4 | 72 | b->cpu = i; |
c4028958 | 73 | INIT_DELAYED_WORK(&b->work, wq_sync_buffer); |
1da177e4 LT |
74 | } |
75 | return 0; | |
76 | ||
77 | fail: | |
78 | free_cpu_buffers(); | |
79 | return -ENOMEM; | |
80 | } | |
1da177e4 LT |
81 | |
82 | void start_cpu_work(void) | |
83 | { | |
84 | int i; | |
85 | ||
86 | work_enabled = 1; | |
87 | ||
88 | for_each_online_cpu(i) { | |
608dfddd | 89 | struct oprofile_cpu_buffer *b = &per_cpu(cpu_buffer, i); |
1da177e4 LT |
90 | |
91 | /* | |
92 | * Spread the work by 1 jiffy per cpu so they dont all | |
93 | * fire at once. | |
94 | */ | |
95 | schedule_delayed_work_on(i, &b->work, DEFAULT_TIMER_EXPIRE + i); | |
96 | } | |
97 | } | |
98 | ||
1da177e4 LT |
99 | void end_cpu_work(void) |
100 | { | |
101 | int i; | |
102 | ||
103 | work_enabled = 0; | |
104 | ||
105 | for_each_online_cpu(i) { | |
608dfddd | 106 | struct oprofile_cpu_buffer *b = &per_cpu(cpu_buffer, i); |
1da177e4 LT |
107 | |
108 | cancel_delayed_work(&b->work); | |
109 | } | |
110 | ||
111 | flush_scheduled_work(); | |
112 | } | |
113 | ||
1da177e4 | 114 | /* Resets the cpu buffer to a sane state. */ |
25ad2913 | 115 | void cpu_buffer_reset(struct oprofile_cpu_buffer *cpu_buf) |
1da177e4 LT |
116 | { |
117 | /* reset these to invalid values; the next sample | |
118 | * collected will populate the buffer with proper | |
119 | * values to initialize the buffer | |
120 | */ | |
121 | cpu_buf->last_is_kernel = -1; | |
122 | cpu_buf->last_task = NULL; | |
123 | } | |
124 | ||
1da177e4 | 125 | /* compute number of available slots in cpu_buffer queue */ |
25ad2913 | 126 | static unsigned long nr_available_slots(struct oprofile_cpu_buffer const *b) |
1da177e4 LT |
127 | { |
128 | unsigned long head = b->head_pos; | |
129 | unsigned long tail = b->tail_pos; | |
130 | ||
131 | if (tail > head) | |
132 | return (tail - head) - 1; | |
133 | ||
134 | return tail + (b->buffer_size - head) - 1; | |
135 | } | |
136 | ||
25ad2913 | 137 | static void increment_head(struct oprofile_cpu_buffer *b) |
1da177e4 LT |
138 | { |
139 | unsigned long new_head = b->head_pos + 1; | |
140 | ||
141 | /* Ensure anything written to the slot before we | |
142 | * increment is visible */ | |
143 | wmb(); | |
144 | ||
145 | if (new_head < b->buffer_size) | |
146 | b->head_pos = new_head; | |
147 | else | |
148 | b->head_pos = 0; | |
149 | } | |
150 | ||
77933d72 | 151 | static inline void |
25ad2913 | 152 | add_sample(struct oprofile_cpu_buffer *cpu_buf, |
6a18037d | 153 | unsigned long pc, unsigned long event) |
1da177e4 | 154 | { |
25ad2913 | 155 | struct op_sample *entry = &cpu_buf->buffer[cpu_buf->head_pos]; |
1da177e4 LT |
156 | entry->eip = pc; |
157 | entry->event = event; | |
158 | increment_head(cpu_buf); | |
159 | } | |
160 | ||
77933d72 | 161 | static inline void |
25ad2913 | 162 | add_code(struct oprofile_cpu_buffer *buffer, unsigned long value) |
1da177e4 LT |
163 | { |
164 | add_sample(buffer, ESCAPE_CODE, value); | |
165 | } | |
166 | ||
1da177e4 LT |
167 | /* This must be safe from any context. It's safe writing here |
168 | * because of the head/tail separation of the writer and reader | |
169 | * of the CPU buffer. | |
170 | * | |
171 | * is_kernel is needed because on some architectures you cannot | |
172 | * tell if you are in kernel or user space simply by looking at | |
173 | * pc. We tag this in the buffer by generating kernel enter/exit | |
174 | * events whenever is_kernel changes | |
175 | */ | |
25ad2913 | 176 | static int log_sample(struct oprofile_cpu_buffer *cpu_buf, unsigned long pc, |
1da177e4 LT |
177 | int is_kernel, unsigned long event) |
178 | { | |
25ad2913 | 179 | struct task_struct *task; |
1da177e4 LT |
180 | |
181 | cpu_buf->sample_received++; | |
182 | ||
df9d177a PE |
183 | if (pc == ESCAPE_CODE) { |
184 | cpu_buf->sample_invalid_eip++; | |
185 | return 0; | |
186 | } | |
187 | ||
1da177e4 LT |
188 | if (nr_available_slots(cpu_buf) < 3) { |
189 | cpu_buf->sample_lost_overflow++; | |
190 | return 0; | |
191 | } | |
192 | ||
193 | is_kernel = !!is_kernel; | |
194 | ||
195 | task = current; | |
196 | ||
197 | /* notice a switch from user->kernel or vice versa */ | |
198 | if (cpu_buf->last_is_kernel != is_kernel) { | |
199 | cpu_buf->last_is_kernel = is_kernel; | |
200 | add_code(cpu_buf, is_kernel); | |
201 | } | |
202 | ||
203 | /* notice a task switch */ | |
204 | if (cpu_buf->last_task != task) { | |
205 | cpu_buf->last_task = task; | |
206 | add_code(cpu_buf, (unsigned long)task); | |
207 | } | |
6a18037d | 208 | |
1da177e4 LT |
209 | add_sample(cpu_buf, pc, event); |
210 | return 1; | |
211 | } | |
212 | ||
345c2573 | 213 | static int oprofile_begin_trace(struct oprofile_cpu_buffer *cpu_buf) |
1da177e4 LT |
214 | { |
215 | if (nr_available_slots(cpu_buf) < 4) { | |
216 | cpu_buf->sample_lost_overflow++; | |
217 | return 0; | |
218 | } | |
219 | ||
220 | add_code(cpu_buf, CPU_TRACE_BEGIN); | |
221 | cpu_buf->tracing = 1; | |
222 | return 1; | |
223 | } | |
224 | ||
25ad2913 | 225 | static void oprofile_end_trace(struct oprofile_cpu_buffer *cpu_buf) |
1da177e4 LT |
226 | { |
227 | cpu_buf->tracing = 0; | |
228 | } | |
229 | ||
27357716 BR |
230 | void oprofile_add_ext_sample(unsigned long pc, struct pt_regs * const regs, |
231 | unsigned long event, int is_kernel) | |
1da177e4 | 232 | { |
608dfddd | 233 | struct oprofile_cpu_buffer *cpu_buf = &__get_cpu_var(cpu_buffer); |
1da177e4 LT |
234 | |
235 | if (!backtrace_depth) { | |
236 | log_sample(cpu_buf, pc, is_kernel, event); | |
237 | return; | |
238 | } | |
239 | ||
240 | if (!oprofile_begin_trace(cpu_buf)) | |
241 | return; | |
242 | ||
243 | /* if log_sample() fail we can't backtrace since we lost the source | |
244 | * of this event */ | |
245 | if (log_sample(cpu_buf, pc, is_kernel, event)) | |
246 | oprofile_ops.backtrace(regs, backtrace_depth); | |
247 | oprofile_end_trace(cpu_buf); | |
248 | } | |
249 | ||
27357716 BR |
250 | void oprofile_add_sample(struct pt_regs * const regs, unsigned long event) |
251 | { | |
252 | int is_kernel = !user_mode(regs); | |
253 | unsigned long pc = profile_pc(regs); | |
254 | ||
255 | oprofile_add_ext_sample(pc, regs, event, is_kernel); | |
256 | } | |
257 | ||
852402cc RR |
258 | #ifdef CONFIG_OPROFILE_IBS |
259 | ||
e2fee276 RR |
260 | #define MAX_IBS_SAMPLE_SIZE 14 |
261 | ||
262 | void oprofile_add_ibs_sample(struct pt_regs *const regs, | |
25ad2913 | 263 | unsigned int *const ibs_sample, int ibs_code) |
345c2573 | 264 | { |
e2fee276 RR |
265 | int is_kernel = !user_mode(regs); |
266 | struct oprofile_cpu_buffer *cpu_buf = &__get_cpu_var(cpu_buffer); | |
345c2573 BK |
267 | struct task_struct *task; |
268 | ||
269 | cpu_buf->sample_received++; | |
270 | ||
271 | if (nr_available_slots(cpu_buf) < MAX_IBS_SAMPLE_SIZE) { | |
e2fee276 | 272 | /* we can't backtrace since we lost the source of this event */ |
345c2573 | 273 | cpu_buf->sample_lost_overflow++; |
e2fee276 | 274 | return; |
345c2573 BK |
275 | } |
276 | ||
345c2573 BK |
277 | /* notice a switch from user->kernel or vice versa */ |
278 | if (cpu_buf->last_is_kernel != is_kernel) { | |
279 | cpu_buf->last_is_kernel = is_kernel; | |
280 | add_code(cpu_buf, is_kernel); | |
281 | } | |
282 | ||
283 | /* notice a task switch */ | |
284 | if (!is_kernel) { | |
285 | task = current; | |
345c2573 BK |
286 | if (cpu_buf->last_task != task) { |
287 | cpu_buf->last_task = task; | |
288 | add_code(cpu_buf, (unsigned long)task); | |
289 | } | |
290 | } | |
291 | ||
292 | add_code(cpu_buf, ibs_code); | |
e2fee276 RR |
293 | add_sample(cpu_buf, ibs_sample[0], ibs_sample[1]); |
294 | add_sample(cpu_buf, ibs_sample[2], ibs_sample[3]); | |
295 | add_sample(cpu_buf, ibs_sample[4], ibs_sample[5]); | |
345c2573 BK |
296 | |
297 | if (ibs_code == IBS_OP_BEGIN) { | |
e2fee276 RR |
298 | add_sample(cpu_buf, ibs_sample[6], ibs_sample[7]); |
299 | add_sample(cpu_buf, ibs_sample[8], ibs_sample[9]); | |
300 | add_sample(cpu_buf, ibs_sample[10], ibs_sample[11]); | |
345c2573 BK |
301 | } |
302 | ||
e2fee276 | 303 | if (backtrace_depth) |
345c2573 BK |
304 | oprofile_ops.backtrace(regs, backtrace_depth); |
305 | } | |
306 | ||
852402cc RR |
307 | #endif |
308 | ||
1da177e4 LT |
309 | void oprofile_add_pc(unsigned long pc, int is_kernel, unsigned long event) |
310 | { | |
608dfddd | 311 | struct oprofile_cpu_buffer *cpu_buf = &__get_cpu_var(cpu_buffer); |
1da177e4 LT |
312 | log_sample(cpu_buf, pc, is_kernel, event); |
313 | } | |
314 | ||
1da177e4 LT |
315 | void oprofile_add_trace(unsigned long pc) |
316 | { | |
608dfddd | 317 | struct oprofile_cpu_buffer *cpu_buf = &__get_cpu_var(cpu_buffer); |
1da177e4 LT |
318 | |
319 | if (!cpu_buf->tracing) | |
320 | return; | |
321 | ||
322 | if (nr_available_slots(cpu_buf) < 1) { | |
323 | cpu_buf->tracing = 0; | |
324 | cpu_buf->sample_lost_overflow++; | |
325 | return; | |
326 | } | |
327 | ||
328 | /* broken frame can give an eip with the same value as an escape code, | |
329 | * abort the trace if we get it */ | |
330 | if (pc == ESCAPE_CODE) { | |
331 | cpu_buf->tracing = 0; | |
332 | cpu_buf->backtrace_aborted++; | |
333 | return; | |
334 | } | |
335 | ||
336 | add_sample(cpu_buf, pc, 0); | |
337 | } | |
338 | ||
1da177e4 LT |
339 | /* |
340 | * This serves to avoid cpu buffer overflow, and makes sure | |
341 | * the task mortuary progresses | |
342 | * | |
343 | * By using schedule_delayed_work_on and then schedule_delayed_work | |
344 | * we guarantee this will stay on the correct cpu | |
345 | */ | |
c4028958 | 346 | static void wq_sync_buffer(struct work_struct *work) |
1da177e4 | 347 | { |
25ad2913 | 348 | struct oprofile_cpu_buffer *b = |
c4028958 | 349 | container_of(work, struct oprofile_cpu_buffer, work.work); |
1da177e4 | 350 | if (b->cpu != smp_processor_id()) { |
bd17b625 | 351 | printk(KERN_DEBUG "WQ on CPU%d, prefer CPU%d\n", |
1da177e4 LT |
352 | smp_processor_id(), b->cpu); |
353 | } | |
354 | sync_buffer(b->cpu); | |
355 | ||
356 | /* don't re-add the work if we're shutting down */ | |
357 | if (work_enabled) | |
358 | schedule_delayed_work(&b->work, DEFAULT_TIMER_EXPIRE); | |
359 | } |