4 * @remark Copyright 2002-2009 OProfile authors
5 * @remark Read the file COPYING
7 * @author John Levon <levon@movementarian.org>
8 * @author Barry Kasindorf
9 * @author Robert Richter <robert.richter@amd.com>
11 * This is the core of the buffer management. Each
12 * CPU buffer is processed and entered into the
13 * global event buffer. Such processing is necessary
14 * in several circumstances, mentioned below.
16 * The processing does the job of converting the
17 * transitory EIP value into a persistent dentry/offset
18 * value that the profiler can record at its leisure.
20 * See fs/dcookies.c for a description of the dentry/offset
24 #include <linux/file.h>
26 #include <linux/workqueue.h>
27 #include <linux/notifier.h>
28 #include <linux/dcookies.h>
29 #include <linux/profile.h>
30 #include <linux/module.h>
32 #include <linux/oprofile.h>
33 #include <linux/sched.h>
34 #include <linux/sched/mm.h>
35 #include <linux/gfp.h>
37 #include "oprofile_stats.h"
38 #include "event_buffer.h"
39 #include "cpu_buffer.h"
40 #include "buffer_sync.h"
42 static LIST_HEAD(dying_tasks);
43 static LIST_HEAD(dead_tasks);
44 static cpumask_var_t marked_cpus;
45 static DEFINE_SPINLOCK(task_mortuary);
46 static void process_task_mortuary(void);
48 /* Take ownership of the task struct and place it on the
49 * list for processing. Only after two full buffer syncs
50 * does the task eventually get freed, because by then
51 * we are sure we will not reference it again.
52 * Can be invoked from softirq via RCU callback due to
53 * call_rcu() of the task struct, hence the _irqsave.
56 task_free_notify(struct notifier_block *self, unsigned long val, void *data)
59 struct task_struct *task = data;
60 spin_lock_irqsave(&task_mortuary, flags);
61 list_add(&task->tasks, &dying_tasks);
62 spin_unlock_irqrestore(&task_mortuary, flags);
67 /* The task is on its way out. A sync of the buffer means we can catch
68 * any remaining samples for this task.
71 task_exit_notify(struct notifier_block *self, unsigned long val, void *data)
73 /* To avoid latency problems, we only process the current CPU,
74 * hoping that most samples for the task are on this CPU
76 sync_buffer(raw_smp_processor_id());
81 /* The task is about to try a do_munmap(). We peek at what it's going to
82 * do, and if it's an executable region, process the samples first, so
83 * we don't lose any. This does not have to be exact, it's a QoI issue
87 munmap_notify(struct notifier_block *self, unsigned long val, void *data)
89 unsigned long addr = (unsigned long)data;
90 struct mm_struct *mm = current->mm;
91 struct vm_area_struct *mpnt;
93 down_read(&mm->mmap_sem);
95 mpnt = find_vma(mm, addr);
96 if (mpnt && mpnt->vm_file && (mpnt->vm_flags & VM_EXEC)) {
97 up_read(&mm->mmap_sem);
98 /* To avoid latency problems, we only process the current CPU,
99 * hoping that most samples for the task are on this CPU
101 sync_buffer(raw_smp_processor_id());
105 up_read(&mm->mmap_sem);
110 /* We need to be told about new modules so we don't attribute to a previously
111 * loaded module, or drop the samples on the floor.
114 module_load_notify(struct notifier_block *self, unsigned long val, void *data)
116 #ifdef CONFIG_MODULES
117 if (val != MODULE_STATE_COMING)
120 /* FIXME: should we process all CPU buffers ? */
121 mutex_lock(&buffer_mutex);
122 add_event_entry(ESCAPE_CODE);
123 add_event_entry(MODULE_LOADED_CODE);
124 mutex_unlock(&buffer_mutex);
130 static struct notifier_block task_free_nb = {
131 .notifier_call = task_free_notify,
134 static struct notifier_block task_exit_nb = {
135 .notifier_call = task_exit_notify,
138 static struct notifier_block munmap_nb = {
139 .notifier_call = munmap_notify,
142 static struct notifier_block module_load_nb = {
143 .notifier_call = module_load_notify,
146 static void free_all_tasks(void)
148 /* make sure we don't leak task structs */
149 process_task_mortuary();
150 process_task_mortuary();
157 if (!zalloc_cpumask_var(&marked_cpus, GFP_KERNEL))
160 err = task_handoff_register(&task_free_nb);
163 err = profile_event_register(PROFILE_TASK_EXIT, &task_exit_nb);
166 err = profile_event_register(PROFILE_MUNMAP, &munmap_nb);
169 err = register_module_notifier(&module_load_nb);
178 profile_event_unregister(PROFILE_MUNMAP, &munmap_nb);
180 profile_event_unregister(PROFILE_TASK_EXIT, &task_exit_nb);
182 task_handoff_unregister(&task_free_nb);
185 free_cpumask_var(marked_cpus);
193 unregister_module_notifier(&module_load_nb);
194 profile_event_unregister(PROFILE_MUNMAP, &munmap_nb);
195 profile_event_unregister(PROFILE_TASK_EXIT, &task_exit_nb);
196 task_handoff_unregister(&task_free_nb);
197 barrier(); /* do all of the above first */
202 free_cpumask_var(marked_cpus);
206 /* Optimisation. We can manage without taking the dcookie sem
207 * because we cannot reach this code without at least one
208 * dcookie user still being registered (namely, the reader
209 * of the event buffer). */
210 static inline unsigned long fast_get_dcookie(const struct path *path)
212 unsigned long cookie;
214 if (path->dentry->d_flags & DCACHE_COOKIE)
215 return (unsigned long)path->dentry;
216 get_dcookie(path, &cookie);
221 /* Look up the dcookie for the task's mm->exe_file,
222 * which corresponds loosely to "application name". This is
223 * not strictly necessary but allows oprofile to associate
224 * shared-library samples with particular applications
226 static unsigned long get_exec_dcookie(struct mm_struct *mm)
228 unsigned long cookie = NO_COOKIE;
229 struct file *exe_file;
234 exe_file = get_mm_exe_file(mm);
238 cookie = fast_get_dcookie(&exe_file->f_path);
245 /* Convert the EIP value of a sample into a persistent dentry/offset
246 * pair that can then be added to the global event buffer. We make
247 * sure to do this lookup before a mm->mmap modification happens so
248 * we don't lose track.
250 * The caller must ensure the mm is not nil (ie: not a kernel thread).
253 lookup_dcookie(struct mm_struct *mm, unsigned long addr, off_t *offset)
255 unsigned long cookie = NO_COOKIE;
256 struct vm_area_struct *vma;
258 down_read(&mm->mmap_sem);
259 for (vma = find_vma(mm, addr); vma; vma = vma->vm_next) {
261 if (addr < vma->vm_start || addr >= vma->vm_end)
265 cookie = fast_get_dcookie(&vma->vm_file->f_path);
266 *offset = (vma->vm_pgoff << PAGE_SHIFT) + addr -
269 /* must be an anonymous map */
277 cookie = INVALID_COOKIE;
278 up_read(&mm->mmap_sem);
283 static unsigned long last_cookie = INVALID_COOKIE;
285 static void add_cpu_switch(int i)
287 add_event_entry(ESCAPE_CODE);
288 add_event_entry(CPU_SWITCH_CODE);
290 last_cookie = INVALID_COOKIE;
293 static void add_kernel_ctx_switch(unsigned int in_kernel)
295 add_event_entry(ESCAPE_CODE);
297 add_event_entry(KERNEL_ENTER_SWITCH_CODE);
299 add_event_entry(KERNEL_EXIT_SWITCH_CODE);
303 add_user_ctx_switch(struct task_struct const *task, unsigned long cookie)
305 add_event_entry(ESCAPE_CODE);
306 add_event_entry(CTX_SWITCH_CODE);
307 add_event_entry(task->pid);
308 add_event_entry(cookie);
309 /* Another code for daemon back-compat */
310 add_event_entry(ESCAPE_CODE);
311 add_event_entry(CTX_TGID_CODE);
312 add_event_entry(task->tgid);
316 static void add_cookie_switch(unsigned long cookie)
318 add_event_entry(ESCAPE_CODE);
319 add_event_entry(COOKIE_SWITCH_CODE);
320 add_event_entry(cookie);
324 static void add_trace_begin(void)
326 add_event_entry(ESCAPE_CODE);
327 add_event_entry(TRACE_BEGIN_CODE);
330 static void add_data(struct op_entry *entry, struct mm_struct *mm)
332 unsigned long code, pc, val;
333 unsigned long cookie;
336 if (!op_cpu_buffer_get_data(entry, &code))
338 if (!op_cpu_buffer_get_data(entry, &pc))
340 if (!op_cpu_buffer_get_size(entry))
344 cookie = lookup_dcookie(mm, pc, &offset);
346 if (cookie == NO_COOKIE)
348 if (cookie == INVALID_COOKIE) {
349 atomic_inc(&oprofile_stats.sample_lost_no_mapping);
352 if (cookie != last_cookie) {
353 add_cookie_switch(cookie);
354 last_cookie = cookie;
359 add_event_entry(ESCAPE_CODE);
360 add_event_entry(code);
361 add_event_entry(offset); /* Offset from Dcookie */
363 while (op_cpu_buffer_get_data(entry, &val))
364 add_event_entry(val);
367 static inline void add_sample_entry(unsigned long offset, unsigned long event)
369 add_event_entry(offset);
370 add_event_entry(event);
375 * Add a sample to the global event buffer. If possible the
376 * sample is converted into a persistent dentry/offset pair
377 * for later lookup from userspace. Return 0 on failure.
380 add_sample(struct mm_struct *mm, struct op_sample *s, int in_kernel)
382 unsigned long cookie;
386 add_sample_entry(s->eip, s->event);
390 /* add userspace sample */
393 atomic_inc(&oprofile_stats.sample_lost_no_mm);
397 cookie = lookup_dcookie(mm, s->eip, &offset);
399 if (cookie == INVALID_COOKIE) {
400 atomic_inc(&oprofile_stats.sample_lost_no_mapping);
404 if (cookie != last_cookie) {
405 add_cookie_switch(cookie);
406 last_cookie = cookie;
409 add_sample_entry(offset, s->event);
415 static void release_mm(struct mm_struct *mm)
422 static inline int is_code(unsigned long val)
424 return val == ESCAPE_CODE;
428 /* Move tasks along towards death. Any tasks on dead_tasks
429 * will definitely have no remaining references in any
430 * CPU buffers at this point, because we use two lists,
431 * and to have reached the list, it must have gone through
432 * one full sync already.
434 static void process_task_mortuary(void)
437 LIST_HEAD(local_dead_tasks);
438 struct task_struct *task;
439 struct task_struct *ttask;
441 spin_lock_irqsave(&task_mortuary, flags);
443 list_splice_init(&dead_tasks, &local_dead_tasks);
444 list_splice_init(&dying_tasks, &dead_tasks);
446 spin_unlock_irqrestore(&task_mortuary, flags);
448 list_for_each_entry_safe(task, ttask, &local_dead_tasks, tasks) {
449 list_del(&task->tasks);
455 static void mark_done(int cpu)
459 cpumask_set_cpu(cpu, marked_cpus);
461 for_each_online_cpu(i) {
462 if (!cpumask_test_cpu(i, marked_cpus))
466 /* All CPUs have been processed at least once,
467 * we can process the mortuary once
469 process_task_mortuary();
471 cpumask_clear(marked_cpus);
475 /* FIXME: this is not sufficient if we implement syscall barrier backtrace
476 * traversal, the code switch to sb_sample_start at first kernel enter/exit
477 * switch so we need a fifth state and some special handling in sync_buffer()
486 /* Sync one of the CPU's buffers into the global event buffer.
487 * Here we need to go through each batch of samples punctuated
488 * by context switch notes, taking the task's mmap_sem and doing
489 * lookup in task->mm->mmap to convert EIP into dcookie/offset
492 void sync_buffer(int cpu)
494 struct mm_struct *mm = NULL;
495 struct mm_struct *oldmm;
497 struct task_struct *new;
498 unsigned long cookie = 0;
500 sync_buffer_state state = sb_buffer_start;
502 unsigned long available;
504 struct op_entry entry;
505 struct op_sample *sample;
507 mutex_lock(&buffer_mutex);
511 op_cpu_buffer_reset(cpu);
512 available = op_cpu_buffer_entries(cpu);
514 for (i = 0; i < available; ++i) {
515 sample = op_cpu_buffer_read_entry(&entry, cpu);
519 if (is_code(sample->eip)) {
520 flags = sample->event;
521 if (flags & TRACE_BEGIN) {
525 if (flags & KERNEL_CTX_SWITCH) {
526 /* kernel/userspace switch */
527 in_kernel = flags & IS_KERNEL;
528 if (state == sb_buffer_start)
529 state = sb_sample_start;
530 add_kernel_ctx_switch(flags & IS_KERNEL);
532 if (flags & USER_CTX_SWITCH
533 && op_cpu_buffer_get_data(&entry, &val)) {
534 /* userspace context switch */
535 new = (struct task_struct *)val;
538 mm = get_task_mm(new);
540 cookie = get_exec_dcookie(mm);
541 add_user_ctx_switch(new, cookie);
543 if (op_cpu_buffer_get_size(&entry))
544 add_data(&entry, mm);
548 if (state < sb_bt_start)
552 if (add_sample(mm, sample, in_kernel))
555 /* ignore backtraces if failed to add a sample */
556 if (state == sb_bt_start) {
557 state = sb_bt_ignore;
558 atomic_inc(&oprofile_stats.bt_lost_no_mapping);
565 mutex_unlock(&buffer_mutex);
568 /* The function can be used to add a buffer worth of data directly to
569 * the kernel buffer. The buffer is assumed to be a circular buffer.
570 * Take the entries from index start and end at index end, wrapping
573 void oprofile_put_buff(unsigned long *buf, unsigned int start,
574 unsigned int stop, unsigned int max)
580 mutex_lock(&buffer_mutex);
582 add_event_entry(buf[i++]);
588 mutex_unlock(&buffer_mutex);