2 * Infrastructure for profiling code inserted by 'gcc -pg'.
4 * Copyright (C) 2007-2008 Steven Rostedt <srostedt@redhat.com>
5 * Copyright (C) 2004-2008 Ingo Molnar <mingo@redhat.com>
7 * Originally ported from the -rt patch by:
8 * Copyright (C) 2007 Arnaldo Carvalho de Melo <acme@redhat.com>
10 * Based on code in the latency_tracer, that is:
12 * Copyright (C) 2004-2006 Ingo Molnar
13 * Copyright (C) 2004 William Lee Irwin III
16 #include <linux/stop_machine.h>
17 #include <linux/clocksource.h>
18 #include <linux/kallsyms.h>
19 #include <linux/seq_file.h>
20 #include <linux/debugfs.h>
21 #include <linux/kthread.h>
22 #include <linux/hardirq.h>
23 #include <linux/ftrace.h>
24 #include <linux/uaccess.h>
25 #include <linux/sysctl.h>
26 #include <linux/hash.h>
27 #include <linux/ctype.h>
28 #include <linux/list.h>
33 static int last_ftrace_enabled;
35 static DEFINE_SPINLOCK(ftrace_lock);
36 static DEFINE_MUTEX(ftrace_sysctl_lock);
38 static struct ftrace_ops ftrace_list_end __read_mostly =
43 static struct ftrace_ops *ftrace_list __read_mostly = &ftrace_list_end;
44 ftrace_func_t ftrace_trace_function __read_mostly = ftrace_stub;
46 /* mcount is defined per arch in assembly */
47 EXPORT_SYMBOL(mcount);
49 notrace void ftrace_list_func(unsigned long ip, unsigned long parent_ip)
51 struct ftrace_ops *op = ftrace_list;
53 /* in case someone actually ports this to alpha! */
54 read_barrier_depends();
56 while (op != &ftrace_list_end) {
58 read_barrier_depends();
59 op->func(ip, parent_ip);
65 * clear_ftrace_function - reset the ftrace function
67 * This NULLs the ftrace function and in essence stops
68 * tracing. There may be lag
70 void clear_ftrace_function(void)
72 ftrace_trace_function = ftrace_stub;
75 static int notrace __register_ftrace_function(struct ftrace_ops *ops)
77 /* Should never be called by interrupts */
78 spin_lock(&ftrace_lock);
80 ops->next = ftrace_list;
82 * We are entering ops into the ftrace_list but another
83 * CPU might be walking that list. We need to make sure
84 * the ops->next pointer is valid before another CPU sees
85 * the ops pointer included into the ftrace_list.
92 * For one func, simply call it directly.
93 * For more than one func, call the chain.
95 if (ops->next == &ftrace_list_end)
96 ftrace_trace_function = ops->func;
98 ftrace_trace_function = ftrace_list_func;
101 spin_unlock(&ftrace_lock);
106 static int notrace __unregister_ftrace_function(struct ftrace_ops *ops)
108 struct ftrace_ops **p;
111 spin_lock(&ftrace_lock);
114 * If we are removing the last function, then simply point
115 * to the ftrace_stub.
117 if (ftrace_list == ops && ops->next == &ftrace_list_end) {
118 ftrace_trace_function = ftrace_stub;
119 ftrace_list = &ftrace_list_end;
123 for (p = &ftrace_list; *p != &ftrace_list_end; p = &(*p)->next)
134 if (ftrace_enabled) {
135 /* If we only have one func left, then call that directly */
136 if (ftrace_list == &ftrace_list_end ||
137 ftrace_list->next == &ftrace_list_end)
138 ftrace_trace_function = ftrace_list->func;
142 spin_unlock(&ftrace_lock);
147 #ifdef CONFIG_DYNAMIC_FTRACE
149 static struct task_struct *ftraced_task;
150 static DECLARE_WAIT_QUEUE_HEAD(ftraced_waiters);
151 static unsigned long ftraced_iteration_counter;
154 FTRACE_ENABLE_CALLS = (1 << 0),
155 FTRACE_DISABLE_CALLS = (1 << 1),
156 FTRACE_UPDATE_TRACE_FUNC = (1 << 2),
157 FTRACE_ENABLE_MCOUNT = (1 << 3),
158 FTRACE_DISABLE_MCOUNT = (1 << 4),
161 static int ftrace_filtered;
163 static struct hlist_head ftrace_hash[FTRACE_HASHSIZE];
165 static DEFINE_PER_CPU(int, ftrace_shutdown_disable_cpu);
167 static DEFINE_SPINLOCK(ftrace_shutdown_lock);
168 static DEFINE_MUTEX(ftraced_lock);
169 static DEFINE_MUTEX(ftrace_filter_lock);
172 struct ftrace_page *next;
174 struct dyn_ftrace records[];
175 } __attribute__((packed));
177 #define ENTRIES_PER_PAGE \
178 ((PAGE_SIZE - sizeof(struct ftrace_page)) / sizeof(struct dyn_ftrace))
180 /* estimate from running different kernels */
181 #define NR_TO_INIT 10000
183 static struct ftrace_page *ftrace_pages_start;
184 static struct ftrace_page *ftrace_pages;
186 static int ftraced_trigger;
187 static int ftraced_suspend;
189 static int ftrace_record_suspend;
192 notrace ftrace_ip_in_hash(unsigned long ip, unsigned long key)
194 struct dyn_ftrace *p;
195 struct hlist_node *t;
198 hlist_for_each_entry(p, t, &ftrace_hash[key], node) {
208 static inline void notrace
209 ftrace_add_hash(struct dyn_ftrace *node, unsigned long key)
211 hlist_add_head(&node->node, &ftrace_hash[key]);
214 static notrace struct dyn_ftrace *ftrace_alloc_dyn_node(unsigned long ip)
216 if (ftrace_pages->index == ENTRIES_PER_PAGE) {
217 if (!ftrace_pages->next)
219 ftrace_pages = ftrace_pages->next;
222 return &ftrace_pages->records[ftrace_pages->index++];
226 ftrace_record_ip(unsigned long ip)
228 struct dyn_ftrace *node;
237 resched = need_resched();
238 preempt_disable_notrace();
240 /* We simply need to protect against recursion */
241 __get_cpu_var(ftrace_shutdown_disable_cpu)++;
242 if (__get_cpu_var(ftrace_shutdown_disable_cpu) != 1)
245 if (unlikely(ftrace_record_suspend))
248 key = hash_long(ip, FTRACE_HASHBITS);
250 WARN_ON_ONCE(key >= FTRACE_HASHSIZE);
252 if (ftrace_ip_in_hash(ip, key))
255 atomic = irqs_disabled();
257 spin_lock_irqsave(&ftrace_shutdown_lock, flags);
259 /* This ip may have hit the hash before the lock */
260 if (ftrace_ip_in_hash(ip, key))
264 * There's a slight race that the ftraced will update the
265 * hash and reset here. If it is already converted, skip it.
267 if (ftrace_ip_converted(ip))
270 node = ftrace_alloc_dyn_node(ip);
276 ftrace_add_hash(node, key);
281 spin_unlock_irqrestore(&ftrace_shutdown_lock, flags);
283 __get_cpu_var(ftrace_shutdown_disable_cpu)--;
285 /* prevent recursion with scheduler */
287 preempt_enable_no_resched_notrace();
289 preempt_enable_notrace();
292 #define FTRACE_ADDR ((long)(&ftrace_caller))
293 #define MCOUNT_ADDR ((long)(&mcount))
296 __ftrace_replace_code(struct dyn_ftrace *rec,
297 unsigned char *old, unsigned char *new, int enable)
304 if (ftrace_filtered && enable) {
307 * If filtering is on:
309 * If this record is set to be filtered and
310 * is enabled then do nothing.
312 * If this record is set to be filtered and
313 * it is not enabled, enable it.
315 * If this record is not set to be filtered
316 * and it is not enabled do nothing.
318 * If this record is not set to be filtered and
319 * it is enabled, disable it.
321 fl = rec->flags & (FTRACE_FL_FILTER | FTRACE_FL_ENABLED);
323 if ((fl == (FTRACE_FL_FILTER | FTRACE_FL_ENABLED)) ||
328 * If it is enabled disable it,
329 * otherwise enable it!
331 if (fl == FTRACE_FL_ENABLED) {
332 /* swap new and old */
334 old = ftrace_call_replace(ip, FTRACE_ADDR);
335 rec->flags &= ~FTRACE_FL_ENABLED;
337 new = ftrace_call_replace(ip, FTRACE_ADDR);
338 rec->flags |= FTRACE_FL_ENABLED;
343 new = ftrace_call_replace(ip, FTRACE_ADDR);
345 old = ftrace_call_replace(ip, FTRACE_ADDR);
348 if (rec->flags & FTRACE_FL_ENABLED)
350 rec->flags |= FTRACE_FL_ENABLED;
352 if (!(rec->flags & FTRACE_FL_ENABLED))
354 rec->flags &= ~FTRACE_FL_ENABLED;
358 failed = ftrace_modify_code(ip, old, new);
360 rec->flags |= FTRACE_FL_FAILED;
363 static void notrace ftrace_replace_code(int enable)
365 unsigned char *new = NULL, *old = NULL;
366 struct dyn_ftrace *rec;
367 struct ftrace_page *pg;
371 old = ftrace_nop_replace();
373 new = ftrace_nop_replace();
375 for (pg = ftrace_pages_start; pg; pg = pg->next) {
376 for (i = 0; i < pg->index; i++) {
377 rec = &pg->records[i];
379 /* don't modify code that has already faulted */
380 if (rec->flags & FTRACE_FL_FAILED)
383 __ftrace_replace_code(rec, old, new, enable);
388 static notrace void ftrace_shutdown_replenish(void)
390 if (ftrace_pages->next)
393 /* allocate another page */
394 ftrace_pages->next = (void *)get_zeroed_page(GFP_KERNEL);
398 ftrace_code_disable(struct dyn_ftrace *rec)
401 unsigned char *nop, *call;
406 nop = ftrace_nop_replace();
407 call = ftrace_call_replace(ip, MCOUNT_ADDR);
409 failed = ftrace_modify_code(ip, call, nop);
411 rec->flags |= FTRACE_FL_FAILED;
414 static int notrace __ftrace_modify_code(void *data)
419 if (*command & FTRACE_ENABLE_CALLS)
420 ftrace_replace_code(1);
421 else if (*command & FTRACE_DISABLE_CALLS)
422 ftrace_replace_code(0);
424 if (*command & FTRACE_UPDATE_TRACE_FUNC)
425 ftrace_update_ftrace_func(ftrace_trace_function);
427 if (*command & FTRACE_ENABLE_MCOUNT) {
428 addr = (unsigned long)ftrace_record_ip;
429 ftrace_mcount_set(&addr);
430 } else if (*command & FTRACE_DISABLE_MCOUNT) {
431 addr = (unsigned long)ftrace_stub;
432 ftrace_mcount_set(&addr);
438 static void notrace ftrace_run_update_code(int command)
440 stop_machine_run(__ftrace_modify_code, &command, NR_CPUS);
443 static ftrace_func_t saved_ftrace_func;
445 static void notrace ftrace_startup(void)
449 mutex_lock(&ftraced_lock);
451 if (ftraced_suspend == 1)
452 command |= FTRACE_ENABLE_CALLS;
454 if (saved_ftrace_func != ftrace_trace_function) {
455 saved_ftrace_func = ftrace_trace_function;
456 command |= FTRACE_UPDATE_TRACE_FUNC;
459 if (!command || !ftrace_enabled)
462 ftrace_run_update_code(command);
464 mutex_unlock(&ftraced_lock);
467 static void notrace ftrace_shutdown(void)
471 mutex_lock(&ftraced_lock);
473 if (!ftraced_suspend)
474 command |= FTRACE_DISABLE_CALLS;
476 if (saved_ftrace_func != ftrace_trace_function) {
477 saved_ftrace_func = ftrace_trace_function;
478 command |= FTRACE_UPDATE_TRACE_FUNC;
481 if (!command || !ftrace_enabled)
484 ftrace_run_update_code(command);
486 mutex_unlock(&ftraced_lock);
489 static void notrace ftrace_startup_sysctl(void)
491 int command = FTRACE_ENABLE_MCOUNT;
493 mutex_lock(&ftraced_lock);
494 /* Force update next time */
495 saved_ftrace_func = NULL;
496 /* ftraced_suspend is true if we want ftrace running */
498 command |= FTRACE_ENABLE_CALLS;
500 ftrace_run_update_code(command);
501 mutex_unlock(&ftraced_lock);
504 static void notrace ftrace_shutdown_sysctl(void)
506 int command = FTRACE_DISABLE_MCOUNT;
508 mutex_lock(&ftraced_lock);
509 /* ftraced_suspend is true if ftrace is running */
511 command |= FTRACE_DISABLE_CALLS;
513 ftrace_run_update_code(command);
514 mutex_unlock(&ftraced_lock);
517 static cycle_t ftrace_update_time;
518 static unsigned long ftrace_update_cnt;
519 unsigned long ftrace_update_tot_cnt;
521 static int notrace __ftrace_update_code(void *ignore)
523 struct dyn_ftrace *p;
524 struct hlist_head head;
525 struct hlist_node *t;
526 int save_ftrace_enabled;
530 /* Don't be recording funcs now */
531 save_ftrace_enabled = ftrace_enabled;
534 start = now(raw_smp_processor_id());
535 ftrace_update_cnt = 0;
537 /* No locks needed, the machine is stopped! */
538 for (i = 0; i < FTRACE_HASHSIZE; i++) {
539 if (hlist_empty(&ftrace_hash[i]))
542 head = ftrace_hash[i];
543 INIT_HLIST_HEAD(&ftrace_hash[i]);
545 /* all CPUS are stopped, we are safe to modify code */
546 hlist_for_each_entry(p, t, &head, node) {
547 ftrace_code_disable(p);
553 stop = now(raw_smp_processor_id());
554 ftrace_update_time = stop - start;
555 ftrace_update_tot_cnt += ftrace_update_cnt;
557 ftrace_enabled = save_ftrace_enabled;
562 static void notrace ftrace_update_code(void)
564 stop_machine_run(__ftrace_update_code, NULL, NR_CPUS);
567 static int notrace ftraced(void *ignore)
571 set_current_state(TASK_INTERRUPTIBLE);
573 while (!kthread_should_stop()) {
575 /* check once a second */
576 schedule_timeout(HZ);
578 mutex_lock(&ftrace_sysctl_lock);
579 mutex_lock(&ftraced_lock);
580 if (ftrace_enabled && ftraced_trigger && !ftraced_suspend) {
581 ftrace_record_suspend++;
582 ftrace_update_code();
583 usecs = nsecs_to_usecs(ftrace_update_time);
584 if (ftrace_update_tot_cnt > 100000) {
585 ftrace_update_tot_cnt = 0;
586 pr_info("hm, dftrace overflow: %lu change%s"
587 " (%lu total) in %lu usec%s\n",
589 ftrace_update_cnt != 1 ? "s" : "",
590 ftrace_update_tot_cnt,
591 usecs, usecs != 1 ? "s" : "");
595 ftrace_record_suspend--;
597 ftraced_iteration_counter++;
598 mutex_unlock(&ftraced_lock);
599 mutex_unlock(&ftrace_sysctl_lock);
601 wake_up_interruptible(&ftraced_waiters);
603 ftrace_shutdown_replenish();
605 set_current_state(TASK_INTERRUPTIBLE);
607 __set_current_state(TASK_RUNNING);
611 static int __init ftrace_dyn_table_alloc(void)
613 struct ftrace_page *pg;
617 /* allocate a few pages */
618 ftrace_pages_start = (void *)get_zeroed_page(GFP_KERNEL);
619 if (!ftrace_pages_start)
623 * Allocate a few more pages.
625 * TODO: have some parser search vmlinux before
626 * final linking to find all calls to ftrace.
628 * a) know how many pages to allocate.
630 * b) set up the table then.
632 * The dynamic code is still necessary for
636 pg = ftrace_pages = ftrace_pages_start;
638 cnt = NR_TO_INIT / ENTRIES_PER_PAGE;
640 for (i = 0; i < cnt; i++) {
641 pg->next = (void *)get_zeroed_page(GFP_KERNEL);
643 /* If we fail, we'll try later anyway */
654 FTRACE_ITER_FILTER = (1 << 0),
655 FTRACE_ITER_CONT = (1 << 1),
658 #define FTRACE_BUFF_MAX (KSYM_SYMBOL_LEN+4) /* room for wildcards */
660 struct ftrace_iterator {
662 struct ftrace_page *pg;
665 unsigned char buffer[FTRACE_BUFF_MAX+1];
670 static void notrace *
671 t_next(struct seq_file *m, void *v, loff_t *pos)
673 struct ftrace_iterator *iter = m->private;
674 struct dyn_ftrace *rec = NULL;
679 if (iter->idx >= iter->pg->index) {
680 if (iter->pg->next) {
681 iter->pg = iter->pg->next;
686 rec = &iter->pg->records[iter->idx++];
687 if ((rec->flags & FTRACE_FL_FAILED) ||
688 ((iter->flags & FTRACE_ITER_FILTER) &&
689 !(rec->flags & FTRACE_FL_FILTER))) {
700 static void *t_start(struct seq_file *m, loff_t *pos)
702 struct ftrace_iterator *iter = m->private;
706 if (*pos != iter->pos) {
707 for (p = t_next(m, p, &l); p && l < *pos; p = t_next(m, p, &l))
711 p = t_next(m, p, &l);
717 static void t_stop(struct seq_file *m, void *p)
721 static int t_show(struct seq_file *m, void *v)
723 struct dyn_ftrace *rec = v;
724 char str[KSYM_SYMBOL_LEN];
729 kallsyms_lookup(rec->ip, NULL, NULL, NULL, str);
731 seq_printf(m, "%s\n", str);
736 static struct seq_operations show_ftrace_seq_ops = {
744 ftrace_avail_open(struct inode *inode, struct file *file)
746 struct ftrace_iterator *iter;
749 iter = kzalloc(sizeof(*iter), GFP_KERNEL);
753 iter->pg = ftrace_pages_start;
756 ret = seq_open(file, &show_ftrace_seq_ops);
758 struct seq_file *m = file->private_data;
768 int ftrace_avail_release(struct inode *inode, struct file *file)
770 struct seq_file *m = (struct seq_file *)file->private_data;
771 struct ftrace_iterator *iter = m->private;
773 seq_release(inode, file);
779 static void notrace ftrace_filter_reset(void)
781 struct ftrace_page *pg;
782 struct dyn_ftrace *rec;
785 /* keep kstop machine from running */
788 pg = ftrace_pages_start;
790 for (i = 0; i < pg->index; i++) {
791 rec = &pg->records[i];
792 if (rec->flags & FTRACE_FL_FAILED)
794 rec->flags &= ~FTRACE_FL_FILTER;
802 ftrace_filter_open(struct inode *inode, struct file *file)
804 struct ftrace_iterator *iter;
807 iter = kzalloc(sizeof(*iter), GFP_KERNEL);
811 mutex_lock(&ftrace_filter_lock);
812 if ((file->f_mode & FMODE_WRITE) &&
813 !(file->f_flags & O_APPEND))
814 ftrace_filter_reset();
816 if (file->f_mode & FMODE_READ) {
817 iter->pg = ftrace_pages_start;
819 iter->flags = FTRACE_ITER_FILTER;
821 ret = seq_open(file, &show_ftrace_seq_ops);
823 struct seq_file *m = file->private_data;
828 file->private_data = iter;
829 mutex_unlock(&ftrace_filter_lock);
834 static ssize_t notrace
835 ftrace_filter_read(struct file *file, char __user *ubuf,
836 size_t cnt, loff_t *ppos)
838 if (file->f_mode & FMODE_READ)
839 return seq_read(file, ubuf, cnt, ppos);
844 static loff_t notrace
845 ftrace_filter_lseek(struct file *file, loff_t offset, int origin)
849 if (file->f_mode & FMODE_READ)
850 ret = seq_lseek(file, offset, origin);
852 file->f_pos = ret = 1;
865 ftrace_match(unsigned char *buff, int len)
867 char str[KSYM_SYMBOL_LEN];
869 struct ftrace_page *pg;
870 struct dyn_ftrace *rec;
871 int type = MATCH_FULL;
872 unsigned i, match = 0, search_len = 0;
874 for (i = 0; i < len; i++) {
875 if (buff[i] == '*') {
877 search = buff + i + 1;
878 type = MATCH_END_ONLY;
879 search_len = len - (i + 1);
881 if (type == MATCH_END_ONLY) {
882 type = MATCH_MIDDLE_ONLY;
885 type = MATCH_FRONT_ONLY;
893 /* keep kstop machine from running */
896 pg = ftrace_pages_start;
898 for (i = 0; i < pg->index; i++) {
902 rec = &pg->records[i];
903 if (rec->flags & FTRACE_FL_FAILED)
905 kallsyms_lookup(rec->ip, NULL, NULL, NULL, str);
908 if (strcmp(str, buff) == 0)
911 case MATCH_FRONT_ONLY:
912 if (memcmp(str, buff, match) == 0)
915 case MATCH_MIDDLE_ONLY:
916 if (strstr(str, search))
920 ptr = strstr(str, search);
921 if (ptr && (ptr[search_len] == 0))
926 rec->flags |= FTRACE_FL_FILTER;
933 static ssize_t notrace
934 ftrace_filter_write(struct file *file, const char __user *ubuf,
935 size_t cnt, loff_t *ppos)
937 struct ftrace_iterator *iter;
945 mutex_lock(&ftrace_filter_lock);
947 if (file->f_mode & FMODE_READ) {
948 struct seq_file *m = file->private_data;
951 iter = file->private_data;
954 iter->flags &= ~FTRACE_ITER_CONT;
955 iter->buffer_idx = 0;
958 ret = get_user(ch, ubuf++);
964 if (!(iter->flags & ~FTRACE_ITER_CONT)) {
965 /* skip white space */
966 while (cnt && isspace(ch)) {
967 ret = get_user(ch, ubuf++);
981 iter->buffer_idx = 0;
984 while (cnt && !isspace(ch)) {
985 if (iter->buffer_idx < FTRACE_BUFF_MAX)
986 iter->buffer[iter->buffer_idx++] = ch;
991 ret = get_user(ch, ubuf++);
1000 iter->buffer[iter->buffer_idx] = 0;
1001 ftrace_match(iter->buffer, iter->buffer_idx);
1002 iter->buffer_idx = 0;
1004 iter->flags |= FTRACE_ITER_CONT;
1007 file->f_pos += read;
1011 mutex_unlock(&ftrace_filter_lock);
1017 * ftrace_set_filter - set a function to filter on in ftrace
1018 * @buf - the string that holds the function filter text.
1019 * @len - the length of the string.
1020 * @reset - non zero to reset all filters before applying this filter.
1022 * Filters denote which functions should be enabled when tracing is enabled.
1023 * If @buf is NULL and reset is set, all functions will be enabled for tracing.
1025 notrace void ftrace_set_filter(unsigned char *buf, int len, int reset)
1027 mutex_lock(&ftrace_filter_lock);
1029 ftrace_filter_reset();
1031 ftrace_match(buf, len);
1032 mutex_unlock(&ftrace_filter_lock);
1036 ftrace_filter_release(struct inode *inode, struct file *file)
1038 struct seq_file *m = (struct seq_file *)file->private_data;
1039 struct ftrace_iterator *iter;
1041 mutex_lock(&ftrace_filter_lock);
1042 if (file->f_mode & FMODE_READ) {
1045 seq_release(inode, file);
1047 iter = file->private_data;
1049 if (iter->buffer_idx) {
1051 iter->buffer[iter->buffer_idx] = 0;
1052 ftrace_match(iter->buffer, iter->buffer_idx);
1055 mutex_lock(&ftrace_sysctl_lock);
1056 mutex_lock(&ftraced_lock);
1057 if (iter->filtered && ftraced_suspend && ftrace_enabled)
1058 ftrace_run_update_code(FTRACE_ENABLE_CALLS);
1059 mutex_unlock(&ftraced_lock);
1060 mutex_unlock(&ftrace_sysctl_lock);
1063 mutex_unlock(&ftrace_filter_lock);
1067 static struct file_operations ftrace_avail_fops = {
1068 .open = ftrace_avail_open,
1070 .llseek = seq_lseek,
1071 .release = ftrace_avail_release,
1074 static struct file_operations ftrace_filter_fops = {
1075 .open = ftrace_filter_open,
1076 .read = ftrace_filter_read,
1077 .write = ftrace_filter_write,
1078 .llseek = ftrace_filter_lseek,
1079 .release = ftrace_filter_release,
1083 * ftrace_force_update - force an update to all recording ftrace functions
1085 * The ftrace dynamic update daemon only wakes up once a second.
1086 * There may be cases where an update needs to be done immediately
1087 * for tests or internal kernel tracing to begin. This function
1088 * wakes the daemon to do an update and will not return until the
1089 * update is complete.
1091 int ftrace_force_update(void)
1093 unsigned long last_counter;
1094 DECLARE_WAITQUEUE(wait, current);
1100 mutex_lock(&ftraced_lock);
1101 last_counter = ftraced_iteration_counter;
1103 set_current_state(TASK_INTERRUPTIBLE);
1104 add_wait_queue(&ftraced_waiters, &wait);
1107 mutex_unlock(&ftraced_lock);
1108 wake_up_process(ftraced_task);
1110 mutex_lock(&ftraced_lock);
1111 if (signal_pending(current)) {
1115 set_current_state(TASK_INTERRUPTIBLE);
1116 } while (last_counter == ftraced_iteration_counter);
1118 mutex_unlock(&ftraced_lock);
1119 remove_wait_queue(&ftraced_waiters, &wait);
1120 set_current_state(TASK_RUNNING);
1125 static __init int ftrace_init_debugfs(void)
1127 struct dentry *d_tracer;
1128 struct dentry *entry;
1130 d_tracer = tracing_init_dentry();
1132 entry = debugfs_create_file("available_filter_functions", 0444,
1133 d_tracer, NULL, &ftrace_avail_fops);
1135 pr_warning("Could not create debugfs "
1136 "'available_filter_functions' entry\n");
1138 entry = debugfs_create_file("set_ftrace_filter", 0644, d_tracer,
1139 NULL, &ftrace_filter_fops);
1141 pr_warning("Could not create debugfs "
1142 "'set_ftrace_filter' entry\n");
1146 fs_initcall(ftrace_init_debugfs);
1148 static int __init notrace ftrace_dynamic_init(void)
1150 struct task_struct *p;
1154 addr = (unsigned long)ftrace_record_ip;
1155 stop_machine_run(ftrace_dyn_arch_init, &addr, NR_CPUS);
1157 /* ftrace_dyn_arch_init places the return code in addr */
1161 ret = ftrace_dyn_table_alloc();
1165 p = kthread_run(ftraced, NULL, "ftraced");
1169 last_ftrace_enabled = ftrace_enabled = 1;
1175 core_initcall(ftrace_dynamic_init);
1177 # define ftrace_startup() do { } while (0)
1178 # define ftrace_shutdown() do { } while (0)
1179 # define ftrace_startup_sysctl() do { } while (0)
1180 # define ftrace_shutdown_sysctl() do { } while (0)
1181 #endif /* CONFIG_DYNAMIC_FTRACE */
1184 * register_ftrace_function - register a function for profiling
1185 * @ops - ops structure that holds the function for profiling.
1187 * Register a function to be called by all functions in the
1190 * Note: @ops->func and all the functions it calls must be labeled
1191 * with "notrace", otherwise it will go into a
1194 int register_ftrace_function(struct ftrace_ops *ops)
1198 mutex_lock(&ftrace_sysctl_lock);
1199 ret = __register_ftrace_function(ops);
1201 mutex_unlock(&ftrace_sysctl_lock);
1207 * unregister_ftrace_function - unresgister a function for profiling.
1208 * @ops - ops structure that holds the function to unregister
1210 * Unregister a function that was added to be called by ftrace profiling.
1212 int unregister_ftrace_function(struct ftrace_ops *ops)
1216 mutex_lock(&ftrace_sysctl_lock);
1217 ret = __unregister_ftrace_function(ops);
1219 mutex_unlock(&ftrace_sysctl_lock);
1225 ftrace_enable_sysctl(struct ctl_table *table, int write,
1226 struct file *file, void __user *buffer, size_t *lenp,
1231 mutex_lock(&ftrace_sysctl_lock);
1233 ret = proc_dointvec(table, write, file, buffer, lenp, ppos);
1235 if (ret || !write || (last_ftrace_enabled == ftrace_enabled))
1238 last_ftrace_enabled = ftrace_enabled;
1240 if (ftrace_enabled) {
1242 ftrace_startup_sysctl();
1244 /* we are starting ftrace again */
1245 if (ftrace_list != &ftrace_list_end) {
1246 if (ftrace_list->next == &ftrace_list_end)
1247 ftrace_trace_function = ftrace_list->func;
1249 ftrace_trace_function = ftrace_list_func;
1253 /* stopping ftrace calls (just send to ftrace_stub) */
1254 ftrace_trace_function = ftrace_stub;
1256 ftrace_shutdown_sysctl();
1260 mutex_unlock(&ftrace_sysctl_lock);