4 * @remark Copyright 2002 OProfile authors
5 * @remark Read the file COPYING
7 * @author John Levon <levon@movementarian.org>
8 * @author Barry Kasindorf
10 * This is the core of the buffer management. Each
11 * CPU buffer is processed and entered into the
12 * global event buffer. Such processing is necessary
13 * in several circumstances, mentioned below.
15 * The processing does the job of converting the
16 * transitory EIP value into a persistent dentry/offset
17 * value that the profiler can record at its leisure.
19 * See fs/dcookies.c for a description of the dentry/offset
24 #include <linux/workqueue.h>
25 #include <linux/notifier.h>
26 #include <linux/dcookies.h>
27 #include <linux/profile.h>
28 #include <linux/module.h>
30 #include <linux/oprofile.h>
31 #include <linux/sched.h>
33 #include "oprofile_stats.h"
34 #include "event_buffer.h"
35 #include "cpu_buffer.h"
36 #include "buffer_sync.h"
38 static LIST_HEAD(dying_tasks
);
39 static LIST_HEAD(dead_tasks
);
40 static cpumask_t marked_cpus
= CPU_MASK_NONE
;
41 static DEFINE_SPINLOCK(task_mortuary
);
42 static void process_task_mortuary(void);
45 /* Take ownership of the task struct and place it on the
46 * list for processing. Only after two full buffer syncs
47 * does the task eventually get freed, because by then
48 * we are sure we will not reference it again.
49 * Can be invoked from softirq via RCU callback due to
50 * call_rcu() of the task struct, hence the _irqsave.
53 task_free_notify(struct notifier_block
*self
, unsigned long val
, void *data
)
56 struct task_struct
*task
= data
;
57 spin_lock_irqsave(&task_mortuary
, flags
);
58 list_add(&task
->tasks
, &dying_tasks
);
59 spin_unlock_irqrestore(&task_mortuary
, flags
);
64 /* The task is on its way out. A sync of the buffer means we can catch
65 * any remaining samples for this task.
68 task_exit_notify(struct notifier_block
*self
, unsigned long val
, void *data
)
70 /* To avoid latency problems, we only process the current CPU,
71 * hoping that most samples for the task are on this CPU
73 sync_buffer(raw_smp_processor_id());
78 /* The task is about to try a do_munmap(). We peek at what it's going to
79 * do, and if it's an executable region, process the samples first, so
80 * we don't lose any. This does not have to be exact, it's a QoI issue
84 munmap_notify(struct notifier_block
*self
, unsigned long val
, void *data
)
86 unsigned long addr
= (unsigned long)data
;
87 struct mm_struct
*mm
= current
->mm
;
88 struct vm_area_struct
*mpnt
;
90 down_read(&mm
->mmap_sem
);
92 mpnt
= find_vma(mm
, addr
);
93 if (mpnt
&& mpnt
->vm_file
&& (mpnt
->vm_flags
& VM_EXEC
)) {
94 up_read(&mm
->mmap_sem
);
95 /* To avoid latency problems, we only process the current CPU,
96 * hoping that most samples for the task are on this CPU
98 sync_buffer(raw_smp_processor_id());
102 up_read(&mm
->mmap_sem
);
107 /* We need to be told about new modules so we don't attribute to a previously
108 * loaded module, or drop the samples on the floor.
111 module_load_notify(struct notifier_block
*self
, unsigned long val
, void *data
)
113 #ifdef CONFIG_MODULES
114 if (val
!= MODULE_STATE_COMING
)
117 /* FIXME: should we process all CPU buffers ? */
118 mutex_lock(&buffer_mutex
);
119 add_event_entry(ESCAPE_CODE
);
120 add_event_entry(MODULE_LOADED_CODE
);
121 mutex_unlock(&buffer_mutex
);
127 static struct notifier_block task_free_nb
= {
128 .notifier_call
= task_free_notify
,
131 static struct notifier_block task_exit_nb
= {
132 .notifier_call
= task_exit_notify
,
135 static struct notifier_block munmap_nb
= {
136 .notifier_call
= munmap_notify
,
139 static struct notifier_block module_load_nb
= {
140 .notifier_call
= module_load_notify
,
144 static void end_sync(void)
147 /* make sure we don't leak task structs */
148 process_task_mortuary();
149 process_task_mortuary();
159 err
= task_handoff_register(&task_free_nb
);
162 err
= profile_event_register(PROFILE_TASK_EXIT
, &task_exit_nb
);
165 err
= profile_event_register(PROFILE_MUNMAP
, &munmap_nb
);
168 err
= register_module_notifier(&module_load_nb
);
175 profile_event_unregister(PROFILE_MUNMAP
, &munmap_nb
);
177 profile_event_unregister(PROFILE_TASK_EXIT
, &task_exit_nb
);
179 task_handoff_unregister(&task_free_nb
);
188 unregister_module_notifier(&module_load_nb
);
189 profile_event_unregister(PROFILE_MUNMAP
, &munmap_nb
);
190 profile_event_unregister(PROFILE_TASK_EXIT
, &task_exit_nb
);
191 task_handoff_unregister(&task_free_nb
);
196 /* Optimisation. We can manage without taking the dcookie sem
197 * because we cannot reach this code without at least one
198 * dcookie user still being registered (namely, the reader
199 * of the event buffer). */
200 static inline unsigned long fast_get_dcookie(struct path
*path
)
202 unsigned long cookie
;
204 if (path
->dentry
->d_cookie
)
205 return (unsigned long)path
->dentry
;
206 get_dcookie(path
, &cookie
);
211 /* Look up the dcookie for the task's first VM_EXECUTABLE mapping,
212 * which corresponds loosely to "application name". This is
213 * not strictly necessary but allows oprofile to associate
214 * shared-library samples with particular applications
216 static unsigned long get_exec_dcookie(struct mm_struct
*mm
)
218 unsigned long cookie
= NO_COOKIE
;
219 struct vm_area_struct
*vma
;
224 for (vma
= mm
->mmap
; vma
; vma
= vma
->vm_next
) {
227 if (!(vma
->vm_flags
& VM_EXECUTABLE
))
229 cookie
= fast_get_dcookie(&vma
->vm_file
->f_path
);
238 /* Convert the EIP value of a sample into a persistent dentry/offset
239 * pair that can then be added to the global event buffer. We make
240 * sure to do this lookup before a mm->mmap modification happens so
241 * we don't lose track.
244 lookup_dcookie(struct mm_struct
*mm
, unsigned long addr
, off_t
*offset
)
246 unsigned long cookie
= NO_COOKIE
;
247 struct vm_area_struct
*vma
;
249 for (vma
= find_vma(mm
, addr
); vma
; vma
= vma
->vm_next
) {
251 if (addr
< vma
->vm_start
|| addr
>= vma
->vm_end
)
255 cookie
= fast_get_dcookie(&vma
->vm_file
->f_path
);
256 *offset
= (vma
->vm_pgoff
<< PAGE_SHIFT
) + addr
-
259 /* must be an anonymous map */
267 cookie
= INVALID_COOKIE
;
272 static void increment_tail(struct oprofile_cpu_buffer
*b
)
274 unsigned long new_tail
= b
->tail_pos
+ 1;
276 rmb(); /* be sure fifo pointers are synchromized */
278 if (new_tail
< b
->buffer_size
)
279 b
->tail_pos
= new_tail
;
284 static unsigned long last_cookie
= INVALID_COOKIE
;
286 static void add_cpu_switch(int i
)
288 add_event_entry(ESCAPE_CODE
);
289 add_event_entry(CPU_SWITCH_CODE
);
291 last_cookie
= INVALID_COOKIE
;
294 static void add_kernel_ctx_switch(unsigned int in_kernel
)
296 add_event_entry(ESCAPE_CODE
);
298 add_event_entry(KERNEL_ENTER_SWITCH_CODE
);
300 add_event_entry(KERNEL_EXIT_SWITCH_CODE
);
304 add_user_ctx_switch(struct task_struct
const *task
, unsigned long cookie
)
306 add_event_entry(ESCAPE_CODE
);
307 add_event_entry(CTX_SWITCH_CODE
);
308 add_event_entry(task
->pid
);
309 add_event_entry(cookie
);
310 /* Another code for daemon back-compat */
311 add_event_entry(ESCAPE_CODE
);
312 add_event_entry(CTX_TGID_CODE
);
313 add_event_entry(task
->tgid
);
317 static void add_cookie_switch(unsigned long cookie
)
319 add_event_entry(ESCAPE_CODE
);
320 add_event_entry(COOKIE_SWITCH_CODE
);
321 add_event_entry(cookie
);
325 static void add_trace_begin(void)
327 add_event_entry(ESCAPE_CODE
);
328 add_event_entry(TRACE_BEGIN_CODE
);
331 #ifdef CONFIG_OPROFILE_IBS
333 #define IBS_FETCH_CODE_SIZE 2
334 #define IBS_OP_CODE_SIZE 5
335 #define IBS_EIP(offset) \
336 (((struct op_sample *)&cpu_buf->buffer[(offset)])->eip)
337 #define IBS_EVENT(offset) \
338 (((struct op_sample *)&cpu_buf->buffer[(offset)])->event)
341 * Add IBS fetch and op entries to event buffer
343 static void add_ibs_begin(struct oprofile_cpu_buffer
*cpu_buf
, int code
,
344 int in_kernel
, struct mm_struct
*mm
)
348 unsigned long ibs_cookie
= 0;
351 increment_tail(cpu_buf
); /* move to RIP entry */
353 rip
= IBS_EIP(cpu_buf
->tail_pos
);
356 rip
+= IBS_EVENT(cpu_buf
->tail_pos
) << 32;
360 ibs_cookie
= lookup_dcookie(mm
, rip
, &offset
);
362 if (ibs_cookie
== NO_COOKIE
)
364 if (ibs_cookie
== INVALID_COOKIE
) {
365 atomic_inc(&oprofile_stats
.sample_lost_no_mapping
);
368 if (ibs_cookie
!= last_cookie
) {
369 add_cookie_switch(ibs_cookie
);
370 last_cookie
= ibs_cookie
;
375 add_event_entry(ESCAPE_CODE
);
376 add_event_entry(code
);
377 add_event_entry(offset
); /* Offset from Dcookie */
379 /* we send the Dcookie offset, but send the raw Linear Add also*/
380 add_event_entry(IBS_EIP(cpu_buf
->tail_pos
));
381 add_event_entry(IBS_EVENT(cpu_buf
->tail_pos
));
383 if (code
== IBS_FETCH_CODE
)
384 count
= IBS_FETCH_CODE_SIZE
; /*IBS FETCH is 2 int64s*/
386 count
= IBS_OP_CODE_SIZE
; /*IBS OP is 5 int64s*/
388 for (i
= 0; i
< count
; i
++) {
389 increment_tail(cpu_buf
);
390 add_event_entry(IBS_EIP(cpu_buf
->tail_pos
));
391 add_event_entry(IBS_EVENT(cpu_buf
->tail_pos
));
397 static void add_sample_entry(unsigned long offset
, unsigned long event
)
399 add_event_entry(offset
);
400 add_event_entry(event
);
404 static int add_us_sample(struct mm_struct
*mm
, struct op_sample
*s
)
406 unsigned long cookie
;
409 cookie
= lookup_dcookie(mm
, s
->eip
, &offset
);
411 if (cookie
== INVALID_COOKIE
) {
412 atomic_inc(&oprofile_stats
.sample_lost_no_mapping
);
416 if (cookie
!= last_cookie
) {
417 add_cookie_switch(cookie
);
418 last_cookie
= cookie
;
421 add_sample_entry(offset
, s
->event
);
427 /* Add a sample to the global event buffer. If possible the
428 * sample is converted into a persistent dentry/offset pair
429 * for later lookup from userspace.
432 add_sample(struct mm_struct
*mm
, struct op_sample
*s
, int in_kernel
)
435 add_sample_entry(s
->eip
, s
->event
);
438 return add_us_sample(mm
, s
);
440 atomic_inc(&oprofile_stats
.sample_lost_no_mm
);
446 static void release_mm(struct mm_struct
*mm
)
450 up_read(&mm
->mmap_sem
);
455 static struct mm_struct
*take_tasks_mm(struct task_struct
*task
)
457 struct mm_struct
*mm
= get_task_mm(task
);
459 down_read(&mm
->mmap_sem
);
464 static inline int is_code(unsigned long val
)
466 return val
== ESCAPE_CODE
;
470 /* "acquire" as many cpu buffer slots as we can */
471 static unsigned long get_slots(struct oprofile_cpu_buffer
*b
)
473 unsigned long head
= b
->head_pos
;
474 unsigned long tail
= b
->tail_pos
;
477 * Subtle. This resets the persistent last_task
478 * and in_kernel values used for switching notes.
479 * BUT, there is a small window between reading
480 * head_pos, and this call, that means samples
481 * can appear at the new head position, but not
482 * be prefixed with the notes for switching
483 * kernel mode or a task switch. This small hole
484 * can lead to mis-attribution or samples where
485 * we don't know if it's in the kernel or not,
486 * at the start of an event buffer.
493 return head
+ (b
->buffer_size
- tail
);
497 /* Move tasks along towards death. Any tasks on dead_tasks
498 * will definitely have no remaining references in any
499 * CPU buffers at this point, because we use two lists,
500 * and to have reached the list, it must have gone through
501 * one full sync already.
503 static void process_task_mortuary(void)
506 LIST_HEAD(local_dead_tasks
);
507 struct task_struct
*task
;
508 struct task_struct
*ttask
;
510 spin_lock_irqsave(&task_mortuary
, flags
);
512 list_splice_init(&dead_tasks
, &local_dead_tasks
);
513 list_splice_init(&dying_tasks
, &dead_tasks
);
515 spin_unlock_irqrestore(&task_mortuary
, flags
);
517 list_for_each_entry_safe(task
, ttask
, &local_dead_tasks
, tasks
) {
518 list_del(&task
->tasks
);
524 static void mark_done(int cpu
)
528 cpu_set(cpu
, marked_cpus
);
530 for_each_online_cpu(i
) {
531 if (!cpu_isset(i
, marked_cpus
))
535 /* All CPUs have been processed at least once,
536 * we can process the mortuary once
538 process_task_mortuary();
540 cpus_clear(marked_cpus
);
544 /* FIXME: this is not sufficient if we implement syscall barrier backtrace
545 * traversal, the code switch to sb_sample_start at first kernel enter/exit
546 * switch so we need a fifth state and some special handling in sync_buffer()
555 /* Sync one of the CPU's buffers into the global event buffer.
556 * Here we need to go through each batch of samples punctuated
557 * by context switch notes, taking the task's mmap_sem and doing
558 * lookup in task->mm->mmap to convert EIP into dcookie/offset
561 void sync_buffer(int cpu
)
563 struct oprofile_cpu_buffer
*cpu_buf
= &per_cpu(cpu_buffer
, cpu
);
564 struct mm_struct
*mm
= NULL
;
565 struct task_struct
*new;
566 unsigned long cookie
= 0;
569 sync_buffer_state state
= sb_buffer_start
;
570 unsigned long available
;
572 mutex_lock(&buffer_mutex
);
576 /* Remember, only we can modify tail_pos */
578 available
= get_slots(cpu_buf
);
580 for (i
= 0; i
< available
; ++i
) {
581 struct op_sample
*s
= &cpu_buf
->buffer
[cpu_buf
->tail_pos
];
583 if (is_code(s
->eip
)) {
584 if (s
->event
<= CPU_IS_KERNEL
) {
585 /* kernel/userspace switch */
586 in_kernel
= s
->event
;
587 if (state
== sb_buffer_start
)
588 state
= sb_sample_start
;
589 add_kernel_ctx_switch(s
->event
);
590 } else if (s
->event
== CPU_TRACE_BEGIN
) {
593 #ifdef CONFIG_OPROFILE_IBS
594 } else if (s
->event
== IBS_FETCH_BEGIN
) {
596 add_ibs_begin(cpu_buf
,
597 IBS_FETCH_CODE
, in_kernel
, mm
);
598 } else if (s
->event
== IBS_OP_BEGIN
) {
600 add_ibs_begin(cpu_buf
,
601 IBS_OP_CODE
, in_kernel
, mm
);
604 struct mm_struct
*oldmm
= mm
;
606 /* userspace context switch */
607 new = (struct task_struct
*)s
->event
;
610 mm
= take_tasks_mm(new);
612 cookie
= get_exec_dcookie(mm
);
613 add_user_ctx_switch(new, cookie
);
615 } else if (state
>= sb_bt_start
&&
616 !add_sample(mm
, s
, in_kernel
)) {
617 if (state
== sb_bt_start
) {
618 state
= sb_bt_ignore
;
619 atomic_inc(&oprofile_stats
.bt_lost_no_mapping
);
623 increment_tail(cpu_buf
);
629 mutex_unlock(&buffer_mutex
);