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);
44 /* Take ownership of the task struct and place it on the
45 * list for processing. Only after two full buffer syncs
46 * does the task eventually get freed, because by then
47 * we are sure we will not reference it again.
48 * Can be invoked from softirq via RCU callback due to
49 * call_rcu() of the task struct, hence the _irqsave.
52 task_free_notify(struct notifier_block
*self
, unsigned long val
, void *data
)
55 struct task_struct
*task
= data
;
56 spin_lock_irqsave(&task_mortuary
, flags
);
57 list_add(&task
->tasks
, &dying_tasks
);
58 spin_unlock_irqrestore(&task_mortuary
, flags
);
63 /* The task is on its way out. A sync of the buffer means we can catch
64 * any remaining samples for this task.
67 task_exit_notify(struct notifier_block
*self
, unsigned long val
, void *data
)
69 /* To avoid latency problems, we only process the current CPU,
70 * hoping that most samples for the task are on this CPU
72 sync_buffer(raw_smp_processor_id());
77 /* The task is about to try a do_munmap(). We peek at what it's going to
78 * do, and if it's an executable region, process the samples first, so
79 * we don't lose any. This does not have to be exact, it's a QoI issue
83 munmap_notify(struct notifier_block
*self
, unsigned long val
, void *data
)
85 unsigned long addr
= (unsigned long)data
;
86 struct mm_struct
*mm
= current
->mm
;
87 struct vm_area_struct
*mpnt
;
89 down_read(&mm
->mmap_sem
);
91 mpnt
= find_vma(mm
, addr
);
92 if (mpnt
&& mpnt
->vm_file
&& (mpnt
->vm_flags
& VM_EXEC
)) {
93 up_read(&mm
->mmap_sem
);
94 /* To avoid latency problems, we only process the current CPU,
95 * hoping that most samples for the task are on this CPU
97 sync_buffer(raw_smp_processor_id());
101 up_read(&mm
->mmap_sem
);
106 /* We need to be told about new modules so we don't attribute to a previously
107 * loaded module, or drop the samples on the floor.
110 module_load_notify(struct notifier_block
*self
, unsigned long val
, void *data
)
112 #ifdef CONFIG_MODULES
113 if (val
!= MODULE_STATE_COMING
)
116 /* FIXME: should we process all CPU buffers ? */
117 mutex_lock(&buffer_mutex
);
118 add_event_entry(ESCAPE_CODE
);
119 add_event_entry(MODULE_LOADED_CODE
);
120 mutex_unlock(&buffer_mutex
);
126 static struct notifier_block task_free_nb
= {
127 .notifier_call
= task_free_notify
,
130 static struct notifier_block task_exit_nb
= {
131 .notifier_call
= task_exit_notify
,
134 static struct notifier_block munmap_nb
= {
135 .notifier_call
= munmap_notify
,
138 static struct notifier_block module_load_nb
= {
139 .notifier_call
= module_load_notify
,
143 static void end_sync(void)
146 /* make sure we don't leak task structs */
147 process_task_mortuary();
148 process_task_mortuary();
158 err
= task_handoff_register(&task_free_nb
);
161 err
= profile_event_register(PROFILE_TASK_EXIT
, &task_exit_nb
);
164 err
= profile_event_register(PROFILE_MUNMAP
, &munmap_nb
);
167 err
= register_module_notifier(&module_load_nb
);
174 profile_event_unregister(PROFILE_MUNMAP
, &munmap_nb
);
176 profile_event_unregister(PROFILE_TASK_EXIT
, &task_exit_nb
);
178 task_handoff_unregister(&task_free_nb
);
187 unregister_module_notifier(&module_load_nb
);
188 profile_event_unregister(PROFILE_MUNMAP
, &munmap_nb
);
189 profile_event_unregister(PROFILE_TASK_EXIT
, &task_exit_nb
);
190 task_handoff_unregister(&task_free_nb
);
195 /* Optimisation. We can manage without taking the dcookie sem
196 * because we cannot reach this code without at least one
197 * dcookie user still being registered (namely, the reader
198 * of the event buffer). */
199 static inline unsigned long fast_get_dcookie(struct path
*path
)
201 unsigned long cookie
;
203 if (path
->dentry
->d_cookie
)
204 return (unsigned long)path
->dentry
;
205 get_dcookie(path
, &cookie
);
210 /* Look up the dcookie for the task's first VM_EXECUTABLE mapping,
211 * which corresponds loosely to "application name". This is
212 * not strictly necessary but allows oprofile to associate
213 * shared-library samples with particular applications
215 static unsigned long get_exec_dcookie(struct mm_struct
*mm
)
217 unsigned long cookie
= NO_COOKIE
;
218 struct vm_area_struct
*vma
;
223 for (vma
= mm
->mmap
; vma
; vma
= vma
->vm_next
) {
226 if (!(vma
->vm_flags
& VM_EXECUTABLE
))
228 cookie
= fast_get_dcookie(&vma
->vm_file
->f_path
);
237 /* Convert the EIP value of a sample into a persistent dentry/offset
238 * pair that can then be added to the global event buffer. We make
239 * sure to do this lookup before a mm->mmap modification happens so
240 * we don't lose track.
243 lookup_dcookie(struct mm_struct
*mm
, unsigned long addr
, off_t
*offset
)
245 unsigned long cookie
= NO_COOKIE
;
246 struct vm_area_struct
*vma
;
248 for (vma
= find_vma(mm
, addr
); vma
; vma
= vma
->vm_next
) {
250 if (addr
< vma
->vm_start
|| addr
>= vma
->vm_end
)
254 cookie
= fast_get_dcookie(&vma
->vm_file
->f_path
);
255 *offset
= (vma
->vm_pgoff
<< PAGE_SHIFT
) + addr
-
258 /* must be an anonymous map */
266 cookie
= INVALID_COOKIE
;
271 static unsigned long last_cookie
= INVALID_COOKIE
;
273 static void add_cpu_switch(int i
)
275 add_event_entry(ESCAPE_CODE
);
276 add_event_entry(CPU_SWITCH_CODE
);
278 last_cookie
= INVALID_COOKIE
;
281 static void add_kernel_ctx_switch(unsigned int in_kernel
)
283 add_event_entry(ESCAPE_CODE
);
285 add_event_entry(KERNEL_ENTER_SWITCH_CODE
);
287 add_event_entry(KERNEL_EXIT_SWITCH_CODE
);
291 add_user_ctx_switch(struct task_struct
const *task
, unsigned long cookie
)
293 add_event_entry(ESCAPE_CODE
);
294 add_event_entry(CTX_SWITCH_CODE
);
295 add_event_entry(task
->pid
);
296 add_event_entry(cookie
);
297 /* Another code for daemon back-compat */
298 add_event_entry(ESCAPE_CODE
);
299 add_event_entry(CTX_TGID_CODE
);
300 add_event_entry(task
->tgid
);
304 static void add_cookie_switch(unsigned long cookie
)
306 add_event_entry(ESCAPE_CODE
);
307 add_event_entry(COOKIE_SWITCH_CODE
);
308 add_event_entry(cookie
);
312 static void add_trace_begin(void)
314 add_event_entry(ESCAPE_CODE
);
315 add_event_entry(TRACE_BEGIN_CODE
);
318 #ifdef CONFIG_OPROFILE_IBS
320 #define IBS_FETCH_CODE_SIZE 2
321 #define IBS_OP_CODE_SIZE 5
324 * Add IBS fetch and op entries to event buffer
326 static void add_ibs_begin(int cpu
, int code
, struct mm_struct
*mm
)
330 unsigned long cookie
= 0;
332 struct op_entry entry
;
333 struct op_sample
*sample
;
335 sample
= op_cpu_buffer_read_entry(&entry
, cpu
);
341 pc
+= sample
->event
<< 32;
345 cookie
= lookup_dcookie(mm
, pc
, &offset
);
347 if (cookie
== NO_COOKIE
)
349 if (cookie
== INVALID_COOKIE
) {
350 atomic_inc(&oprofile_stats
.sample_lost_no_mapping
);
353 if (cookie
!= last_cookie
) {
354 add_cookie_switch(cookie
);
355 last_cookie
= cookie
;
360 add_event_entry(ESCAPE_CODE
);
361 add_event_entry(code
);
362 add_event_entry(offset
); /* Offset from Dcookie */
364 /* we send the Dcookie offset, but send the raw Linear Add also*/
365 add_event_entry(sample
->eip
);
366 add_event_entry(sample
->event
);
368 if (code
== IBS_FETCH_CODE
)
369 count
= IBS_FETCH_CODE_SIZE
; /*IBS FETCH is 2 int64s*/
371 count
= IBS_OP_CODE_SIZE
; /*IBS OP is 5 int64s*/
373 for (i
= 0; i
< count
; i
++) {
374 sample
= op_cpu_buffer_read_entry(&entry
, cpu
);
377 add_event_entry(sample
->eip
);
378 add_event_entry(sample
->event
);
386 static inline void add_sample_entry(unsigned long offset
, unsigned long event
)
388 add_event_entry(offset
);
389 add_event_entry(event
);
394 * Add a sample to the global event buffer. If possible the
395 * sample is converted into a persistent dentry/offset pair
396 * for later lookup from userspace. Return 0 on failure.
399 add_sample(struct mm_struct
*mm
, struct op_sample
*s
, int in_kernel
)
401 unsigned long cookie
;
405 add_sample_entry(s
->eip
, s
->event
);
409 /* add userspace sample */
412 atomic_inc(&oprofile_stats
.sample_lost_no_mm
);
416 cookie
= lookup_dcookie(mm
, s
->eip
, &offset
);
418 if (cookie
== INVALID_COOKIE
) {
419 atomic_inc(&oprofile_stats
.sample_lost_no_mapping
);
423 if (cookie
!= last_cookie
) {
424 add_cookie_switch(cookie
);
425 last_cookie
= cookie
;
428 add_sample_entry(offset
, s
->event
);
434 static void release_mm(struct mm_struct
*mm
)
438 up_read(&mm
->mmap_sem
);
443 static struct mm_struct
*take_tasks_mm(struct task_struct
*task
)
445 struct mm_struct
*mm
= get_task_mm(task
);
447 down_read(&mm
->mmap_sem
);
452 static inline int is_code(unsigned long val
)
454 return val
== ESCAPE_CODE
;
458 /* Move tasks along towards death. Any tasks on dead_tasks
459 * will definitely have no remaining references in any
460 * CPU buffers at this point, because we use two lists,
461 * and to have reached the list, it must have gone through
462 * one full sync already.
464 static void process_task_mortuary(void)
467 LIST_HEAD(local_dead_tasks
);
468 struct task_struct
*task
;
469 struct task_struct
*ttask
;
471 spin_lock_irqsave(&task_mortuary
, flags
);
473 list_splice_init(&dead_tasks
, &local_dead_tasks
);
474 list_splice_init(&dying_tasks
, &dead_tasks
);
476 spin_unlock_irqrestore(&task_mortuary
, flags
);
478 list_for_each_entry_safe(task
, ttask
, &local_dead_tasks
, tasks
) {
479 list_del(&task
->tasks
);
485 static void mark_done(int cpu
)
489 cpu_set(cpu
, marked_cpus
);
491 for_each_online_cpu(i
) {
492 if (!cpu_isset(i
, marked_cpus
))
496 /* All CPUs have been processed at least once,
497 * we can process the mortuary once
499 process_task_mortuary();
501 cpus_clear(marked_cpus
);
505 /* FIXME: this is not sufficient if we implement syscall barrier backtrace
506 * traversal, the code switch to sb_sample_start at first kernel enter/exit
507 * switch so we need a fifth state and some special handling in sync_buffer()
516 /* Sync one of the CPU's buffers into the global event buffer.
517 * Here we need to go through each batch of samples punctuated
518 * by context switch notes, taking the task's mmap_sem and doing
519 * lookup in task->mm->mmap to convert EIP into dcookie/offset
522 void sync_buffer(int cpu
)
524 struct mm_struct
*mm
= NULL
;
525 struct mm_struct
*oldmm
;
526 struct task_struct
*new;
527 unsigned long cookie
= 0;
529 sync_buffer_state state
= sb_buffer_start
;
531 unsigned long available
;
532 struct op_entry entry
;
533 struct op_sample
*sample
;
535 mutex_lock(&buffer_mutex
);
539 op_cpu_buffer_reset(cpu
);
540 available
= op_cpu_buffer_entries(cpu
);
542 for (i
= 0; i
< available
; ++i
) {
543 sample
= op_cpu_buffer_read_entry(&entry
, cpu
);
547 if (is_code(sample
->eip
)) {
548 switch (sample
->event
) {
551 /* kernel/userspace switch */
552 in_kernel
= sample
->event
;
553 if (state
== sb_buffer_start
)
554 state
= sb_sample_start
;
555 add_kernel_ctx_switch(sample
->event
);
557 case CPU_TRACE_BEGIN
:
561 #ifdef CONFIG_OPROFILE_IBS
562 case IBS_FETCH_BEGIN
:
563 add_ibs_begin(cpu
, IBS_FETCH_CODE
, mm
);
566 add_ibs_begin(cpu
, IBS_OP_CODE
, mm
);
570 /* userspace context switch */
572 new = (struct task_struct
*)sample
->event
;
574 mm
= take_tasks_mm(new);
576 cookie
= get_exec_dcookie(mm
);
577 add_user_ctx_switch(new, cookie
);
583 if (state
< sb_bt_start
)
587 if (add_sample(mm
, sample
, in_kernel
))
590 /* ignore backtraces if failed to add a sample */
591 if (state
== sb_bt_start
) {
592 state
= sb_bt_ignore
;
593 atomic_inc(&oprofile_stats
.bt_lost_no_mapping
);
600 mutex_unlock(&buffer_mutex
);
603 /* The function can be used to add a buffer worth of data directly to
604 * the kernel buffer. The buffer is assumed to be a circular buffer.
605 * Take the entries from index start and end at index end, wrapping
608 void oprofile_put_buff(unsigned long *buf
, unsigned int start
,
609 unsigned int stop
, unsigned int max
)
615 mutex_lock(&buffer_mutex
);
617 add_event_entry(buf
[i
++]);
623 mutex_unlock(&buffer_mutex
);