x86/oprofile: add IBS support for AMD CPUs, IBS buffer handling routines
[linux-2.6.git] / drivers / oprofile / cpu_buffer.c
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>
8  * @author Barry Kasindorf <barry.kasindorf@amd.com>
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>
25  
26 #include "event_buffer.h"
27 #include "cpu_buffer.h"
28 #include "buffer_sync.h"
29 #include "oprof.h"
30
31 DEFINE_PER_CPU(struct oprofile_cpu_buffer, cpu_buffer);
32
33 static void wq_sync_buffer(struct work_struct *work);
34
35 #define DEFAULT_TIMER_EXPIRE (HZ / 10)
36 static int work_enabled;
37
38 void free_cpu_buffers(void)
39 {
40         int i;
41  
42         for_each_online_cpu(i)
43                 vfree(per_cpu(cpu_buffer, i).buffer);
44 }
45
46 int alloc_cpu_buffers(void)
47 {
48         int i;
49  
50         unsigned long buffer_size = fs_cpu_buffer_size;
51  
52         for_each_online_cpu(i) {
53                 struct oprofile_cpu_buffer *b = &per_cpu(cpu_buffer, i);
54  
55                 b->buffer = vmalloc_node(sizeof(struct op_sample) * buffer_size,
56                         cpu_to_node(i));
57                 if (!b->buffer)
58                         goto fail;
59  
60                 b->last_task = NULL;
61                 b->last_is_kernel = -1;
62                 b->tracing = 0;
63                 b->buffer_size = buffer_size;
64                 b->tail_pos = 0;
65                 b->head_pos = 0;
66                 b->sample_received = 0;
67                 b->sample_lost_overflow = 0;
68                 b->backtrace_aborted = 0;
69                 b->sample_invalid_eip = 0;
70                 b->cpu = i;
71                 INIT_DELAYED_WORK(&b->work, wq_sync_buffer);
72         }
73         return 0;
74
75 fail:
76         free_cpu_buffers();
77         return -ENOMEM;
78 }
79
80 void start_cpu_work(void)
81 {
82         int i;
83
84         work_enabled = 1;
85
86         for_each_online_cpu(i) {
87                 struct oprofile_cpu_buffer *b = &per_cpu(cpu_buffer, i);
88
89                 /*
90                  * Spread the work by 1 jiffy per cpu so they dont all
91                  * fire at once.
92                  */
93                 schedule_delayed_work_on(i, &b->work, DEFAULT_TIMER_EXPIRE + i);
94         }
95 }
96
97 void end_cpu_work(void)
98 {
99         int i;
100
101         work_enabled = 0;
102
103         for_each_online_cpu(i) {
104                 struct oprofile_cpu_buffer *b = &per_cpu(cpu_buffer, i);
105
106                 cancel_delayed_work(&b->work);
107         }
108
109         flush_scheduled_work();
110 }
111
112 /* Resets the cpu buffer to a sane state. */
113 void cpu_buffer_reset(struct oprofile_cpu_buffer * cpu_buf)
114 {
115         /* reset these to invalid values; the next sample
116          * collected will populate the buffer with proper
117          * values to initialize the buffer
118          */
119         cpu_buf->last_is_kernel = -1;
120         cpu_buf->last_task = NULL;
121 }
122
123 /* compute number of available slots in cpu_buffer queue */
124 static unsigned long nr_available_slots(struct oprofile_cpu_buffer const * b)
125 {
126         unsigned long head = b->head_pos;
127         unsigned long tail = b->tail_pos;
128
129         if (tail > head)
130                 return (tail - head) - 1;
131
132         return tail + (b->buffer_size - head) - 1;
133 }
134
135 static void increment_head(struct oprofile_cpu_buffer * b)
136 {
137         unsigned long new_head = b->head_pos + 1;
138
139         /* Ensure anything written to the slot before we
140          * increment is visible */
141         wmb();
142
143         if (new_head < b->buffer_size)
144                 b->head_pos = new_head;
145         else
146                 b->head_pos = 0;
147 }
148
149 static inline void
150 add_sample(struct oprofile_cpu_buffer * cpu_buf,
151            unsigned long pc, unsigned long event)
152 {
153         struct op_sample * entry = &cpu_buf->buffer[cpu_buf->head_pos];
154         entry->eip = pc;
155         entry->event = event;
156         increment_head(cpu_buf);
157 }
158
159 static inline void
160 add_code(struct oprofile_cpu_buffer * buffer, unsigned long value)
161 {
162         add_sample(buffer, ESCAPE_CODE, value);
163 }
164
165 /* This must be safe from any context. It's safe writing here
166  * because of the head/tail separation of the writer and reader
167  * of the CPU buffer.
168  *
169  * is_kernel is needed because on some architectures you cannot
170  * tell if you are in kernel or user space simply by looking at
171  * pc. We tag this in the buffer by generating kernel enter/exit
172  * events whenever is_kernel changes
173  */
174 static int log_sample(struct oprofile_cpu_buffer * cpu_buf, unsigned long pc,
175                       int is_kernel, unsigned long event)
176 {
177         struct task_struct * task;
178
179         cpu_buf->sample_received++;
180
181         if (pc == ESCAPE_CODE) {
182                 cpu_buf->sample_invalid_eip++;
183                 return 0;
184         }
185
186         if (nr_available_slots(cpu_buf) < 3) {
187                 cpu_buf->sample_lost_overflow++;
188                 return 0;
189         }
190
191         is_kernel = !!is_kernel;
192
193         task = current;
194
195         /* notice a switch from user->kernel or vice versa */
196         if (cpu_buf->last_is_kernel != is_kernel) {
197                 cpu_buf->last_is_kernel = is_kernel;
198                 add_code(cpu_buf, is_kernel);
199         }
200
201         /* notice a task switch */
202         if (cpu_buf->last_task != task) {
203                 cpu_buf->last_task = task;
204                 add_code(cpu_buf, (unsigned long)task);
205         }
206  
207         add_sample(cpu_buf, pc, event);
208         return 1;
209 }
210
211 static int oprofile_begin_trace(struct oprofile_cpu_buffer *cpu_buf)
212 {
213         if (nr_available_slots(cpu_buf) < 4) {
214                 cpu_buf->sample_lost_overflow++;
215                 return 0;
216         }
217
218         add_code(cpu_buf, CPU_TRACE_BEGIN);
219         cpu_buf->tracing = 1;
220         return 1;
221 }
222
223 static void oprofile_end_trace(struct oprofile_cpu_buffer * cpu_buf)
224 {
225         cpu_buf->tracing = 0;
226 }
227
228 void oprofile_add_ext_sample(unsigned long pc, struct pt_regs * const regs,
229                                 unsigned long event, int is_kernel)
230 {
231         struct oprofile_cpu_buffer *cpu_buf = &__get_cpu_var(cpu_buffer);
232
233         if (!backtrace_depth) {
234                 log_sample(cpu_buf, pc, is_kernel, event);
235                 return;
236         }
237
238         if (!oprofile_begin_trace(cpu_buf))
239                 return;
240
241         /* if log_sample() fail we can't backtrace since we lost the source
242          * of this event */
243         if (log_sample(cpu_buf, pc, is_kernel, event))
244                 oprofile_ops.backtrace(regs, backtrace_depth);
245         oprofile_end_trace(cpu_buf);
246 }
247
248 void oprofile_add_sample(struct pt_regs * const regs, unsigned long event)
249 {
250         int is_kernel = !user_mode(regs);
251         unsigned long pc = profile_pc(regs);
252
253         oprofile_add_ext_sample(pc, regs, event, is_kernel);
254 }
255
256 #define MAX_IBS_SAMPLE_SIZE     14
257 static int log_ibs_sample(struct oprofile_cpu_buffer *cpu_buf,
258         unsigned long pc, int is_kernel, unsigned  int *ibs, int ibs_code)
259 {
260         struct task_struct *task;
261
262         cpu_buf->sample_received++;
263
264         if (nr_available_slots(cpu_buf) < MAX_IBS_SAMPLE_SIZE) {
265                 cpu_buf->sample_lost_overflow++;
266                 return 0;
267         }
268
269         is_kernel = !!is_kernel;
270
271         /* notice a switch from user->kernel or vice versa */
272         if (cpu_buf->last_is_kernel != is_kernel) {
273                 cpu_buf->last_is_kernel = is_kernel;
274                 add_code(cpu_buf, is_kernel);
275         }
276
277         /* notice a task switch */
278         if (!is_kernel) {
279                 task = current;
280
281                 if (cpu_buf->last_task != task) {
282                         cpu_buf->last_task = task;
283                         add_code(cpu_buf, (unsigned long)task);
284                 }
285         }
286
287         add_code(cpu_buf, ibs_code);
288         add_sample(cpu_buf, ibs[0], ibs[1]);
289         add_sample(cpu_buf, ibs[2], ibs[3]);
290         add_sample(cpu_buf, ibs[4], ibs[5]);
291
292         if (ibs_code == IBS_OP_BEGIN) {
293         add_sample(cpu_buf, ibs[6], ibs[7]);
294         add_sample(cpu_buf, ibs[8], ibs[9]);
295         add_sample(cpu_buf, ibs[10], ibs[11]);
296         }
297
298         return 1;
299 }
300
301 void oprofile_add_ibs_sample(struct pt_regs *const regs,
302                                 unsigned int * const ibs_sample, u8 code)
303 {
304         int is_kernel = !user_mode(regs);
305         unsigned long pc = profile_pc(regs);
306
307         struct oprofile_cpu_buffer *cpu_buf =
308                          &per_cpu(cpu_buffer, smp_processor_id());
309
310         if (!backtrace_depth) {
311                 log_ibs_sample(cpu_buf, pc, is_kernel, ibs_sample, code);
312                 return;
313         }
314
315         /* if log_sample() fails we can't backtrace since we lost the source
316         * of this event */
317         if (log_ibs_sample(cpu_buf, pc, is_kernel, ibs_sample, code))
318                 oprofile_ops.backtrace(regs, backtrace_depth);
319 }
320
321 void oprofile_add_pc(unsigned long pc, int is_kernel, unsigned long event)
322 {
323         struct oprofile_cpu_buffer *cpu_buf = &__get_cpu_var(cpu_buffer);
324         log_sample(cpu_buf, pc, is_kernel, event);
325 }
326
327 void oprofile_add_trace(unsigned long pc)
328 {
329         struct oprofile_cpu_buffer *cpu_buf = &__get_cpu_var(cpu_buffer);
330
331         if (!cpu_buf->tracing)
332                 return;
333
334         if (nr_available_slots(cpu_buf) < 1) {
335                 cpu_buf->tracing = 0;
336                 cpu_buf->sample_lost_overflow++;
337                 return;
338         }
339
340         /* broken frame can give an eip with the same value as an escape code,
341          * abort the trace if we get it */
342         if (pc == ESCAPE_CODE) {
343                 cpu_buf->tracing = 0;
344                 cpu_buf->backtrace_aborted++;
345                 return;
346         }
347
348         add_sample(cpu_buf, pc, 0);
349 }
350
351 /*
352  * This serves to avoid cpu buffer overflow, and makes sure
353  * the task mortuary progresses
354  *
355  * By using schedule_delayed_work_on and then schedule_delayed_work
356  * we guarantee this will stay on the correct cpu
357  */
358 static void wq_sync_buffer(struct work_struct *work)
359 {
360         struct oprofile_cpu_buffer * b =
361                 container_of(work, struct oprofile_cpu_buffer, work.work);
362         if (b->cpu != smp_processor_id()) {
363                 printk("WQ on CPU%d, prefer CPU%d\n",
364                        smp_processor_id(), b->cpu);
365         }
366         sync_buffer(b->cpu);
367
368         /* don't re-add the work if we're shutting down */
369         if (work_enabled)
370                 schedule_delayed_work(&b->work, DEFAULT_TIMER_EXPIRE);
371 }