Linux 5.2
[sfrench/cifs-2.6.git] / kernel / trace / trace.c
1 // SPDX-License-Identifier: GPL-2.0
2 /*
3  * ring buffer based function tracer
4  *
5  * Copyright (C) 2007-2012 Steven Rostedt <srostedt@redhat.com>
6  * Copyright (C) 2008 Ingo Molnar <mingo@redhat.com>
7  *
8  * Originally taken from the RT patch by:
9  *    Arnaldo Carvalho de Melo <acme@redhat.com>
10  *
11  * Based on code from the latency_tracer, that is:
12  *  Copyright (C) 2004-2006 Ingo Molnar
13  *  Copyright (C) 2004 Nadia Yvette Chambers
14  */
15 #include <linux/ring_buffer.h>
16 #include <generated/utsrelease.h>
17 #include <linux/stacktrace.h>
18 #include <linux/writeback.h>
19 #include <linux/kallsyms.h>
20 #include <linux/seq_file.h>
21 #include <linux/notifier.h>
22 #include <linux/irqflags.h>
23 #include <linux/debugfs.h>
24 #include <linux/tracefs.h>
25 #include <linux/pagemap.h>
26 #include <linux/hardirq.h>
27 #include <linux/linkage.h>
28 #include <linux/uaccess.h>
29 #include <linux/vmalloc.h>
30 #include <linux/ftrace.h>
31 #include <linux/module.h>
32 #include <linux/percpu.h>
33 #include <linux/splice.h>
34 #include <linux/kdebug.h>
35 #include <linux/string.h>
36 #include <linux/mount.h>
37 #include <linux/rwsem.h>
38 #include <linux/slab.h>
39 #include <linux/ctype.h>
40 #include <linux/init.h>
41 #include <linux/poll.h>
42 #include <linux/nmi.h>
43 #include <linux/fs.h>
44 #include <linux/trace.h>
45 #include <linux/sched/clock.h>
46 #include <linux/sched/rt.h>
47
48 #include "trace.h"
49 #include "trace_output.h"
50
51 /*
52  * On boot up, the ring buffer is set to the minimum size, so that
53  * we do not waste memory on systems that are not using tracing.
54  */
55 bool ring_buffer_expanded;
56
57 /*
58  * We need to change this state when a selftest is running.
59  * A selftest will lurk into the ring-buffer to count the
60  * entries inserted during the selftest although some concurrent
61  * insertions into the ring-buffer such as trace_printk could occurred
62  * at the same time, giving false positive or negative results.
63  */
64 static bool __read_mostly tracing_selftest_running;
65
66 /*
67  * If a tracer is running, we do not want to run SELFTEST.
68  */
69 bool __read_mostly tracing_selftest_disabled;
70
71 /* Pipe tracepoints to printk */
72 struct trace_iterator *tracepoint_print_iter;
73 int tracepoint_printk;
74 static DEFINE_STATIC_KEY_FALSE(tracepoint_printk_key);
75
76 /* For tracers that don't implement custom flags */
77 static struct tracer_opt dummy_tracer_opt[] = {
78         { }
79 };
80
81 static int
82 dummy_set_flag(struct trace_array *tr, u32 old_flags, u32 bit, int set)
83 {
84         return 0;
85 }
86
87 /*
88  * To prevent the comm cache from being overwritten when no
89  * tracing is active, only save the comm when a trace event
90  * occurred.
91  */
92 static DEFINE_PER_CPU(bool, trace_taskinfo_save);
93
94 /*
95  * Kill all tracing for good (never come back).
96  * It is initialized to 1 but will turn to zero if the initialization
97  * of the tracer is successful. But that is the only place that sets
98  * this back to zero.
99  */
100 static int tracing_disabled = 1;
101
102 cpumask_var_t __read_mostly     tracing_buffer_mask;
103
104 /*
105  * ftrace_dump_on_oops - variable to dump ftrace buffer on oops
106  *
107  * If there is an oops (or kernel panic) and the ftrace_dump_on_oops
108  * is set, then ftrace_dump is called. This will output the contents
109  * of the ftrace buffers to the console.  This is very useful for
110  * capturing traces that lead to crashes and outputing it to a
111  * serial console.
112  *
113  * It is default off, but you can enable it with either specifying
114  * "ftrace_dump_on_oops" in the kernel command line, or setting
115  * /proc/sys/kernel/ftrace_dump_on_oops
116  * Set 1 if you want to dump buffers of all CPUs
117  * Set 2 if you want to dump the buffer of the CPU that triggered oops
118  */
119
120 enum ftrace_dump_mode ftrace_dump_on_oops;
121
122 /* When set, tracing will stop when a WARN*() is hit */
123 int __disable_trace_on_warning;
124
125 #ifdef CONFIG_TRACE_EVAL_MAP_FILE
126 /* Map of enums to their values, for "eval_map" file */
127 struct trace_eval_map_head {
128         struct module                   *mod;
129         unsigned long                   length;
130 };
131
132 union trace_eval_map_item;
133
134 struct trace_eval_map_tail {
135         /*
136          * "end" is first and points to NULL as it must be different
137          * than "mod" or "eval_string"
138          */
139         union trace_eval_map_item       *next;
140         const char                      *end;   /* points to NULL */
141 };
142
143 static DEFINE_MUTEX(trace_eval_mutex);
144
145 /*
146  * The trace_eval_maps are saved in an array with two extra elements,
147  * one at the beginning, and one at the end. The beginning item contains
148  * the count of the saved maps (head.length), and the module they
149  * belong to if not built in (head.mod). The ending item contains a
150  * pointer to the next array of saved eval_map items.
151  */
152 union trace_eval_map_item {
153         struct trace_eval_map           map;
154         struct trace_eval_map_head      head;
155         struct trace_eval_map_tail      tail;
156 };
157
158 static union trace_eval_map_item *trace_eval_maps;
159 #endif /* CONFIG_TRACE_EVAL_MAP_FILE */
160
161 static int tracing_set_tracer(struct trace_array *tr, const char *buf);
162
163 #define MAX_TRACER_SIZE         100
164 static char bootup_tracer_buf[MAX_TRACER_SIZE] __initdata;
165 static char *default_bootup_tracer;
166
167 static bool allocate_snapshot;
168
169 static int __init set_cmdline_ftrace(char *str)
170 {
171         strlcpy(bootup_tracer_buf, str, MAX_TRACER_SIZE);
172         default_bootup_tracer = bootup_tracer_buf;
173         /* We are using ftrace early, expand it */
174         ring_buffer_expanded = true;
175         return 1;
176 }
177 __setup("ftrace=", set_cmdline_ftrace);
178
179 static int __init set_ftrace_dump_on_oops(char *str)
180 {
181         if (*str++ != '=' || !*str) {
182                 ftrace_dump_on_oops = DUMP_ALL;
183                 return 1;
184         }
185
186         if (!strcmp("orig_cpu", str)) {
187                 ftrace_dump_on_oops = DUMP_ORIG;
188                 return 1;
189         }
190
191         return 0;
192 }
193 __setup("ftrace_dump_on_oops", set_ftrace_dump_on_oops);
194
195 static int __init stop_trace_on_warning(char *str)
196 {
197         if ((strcmp(str, "=0") != 0 && strcmp(str, "=off") != 0))
198                 __disable_trace_on_warning = 1;
199         return 1;
200 }
201 __setup("traceoff_on_warning", stop_trace_on_warning);
202
203 static int __init boot_alloc_snapshot(char *str)
204 {
205         allocate_snapshot = true;
206         /* We also need the main ring buffer expanded */
207         ring_buffer_expanded = true;
208         return 1;
209 }
210 __setup("alloc_snapshot", boot_alloc_snapshot);
211
212
213 static char trace_boot_options_buf[MAX_TRACER_SIZE] __initdata;
214
215 static int __init set_trace_boot_options(char *str)
216 {
217         strlcpy(trace_boot_options_buf, str, MAX_TRACER_SIZE);
218         return 0;
219 }
220 __setup("trace_options=", set_trace_boot_options);
221
222 static char trace_boot_clock_buf[MAX_TRACER_SIZE] __initdata;
223 static char *trace_boot_clock __initdata;
224
225 static int __init set_trace_boot_clock(char *str)
226 {
227         strlcpy(trace_boot_clock_buf, str, MAX_TRACER_SIZE);
228         trace_boot_clock = trace_boot_clock_buf;
229         return 0;
230 }
231 __setup("trace_clock=", set_trace_boot_clock);
232
233 static int __init set_tracepoint_printk(char *str)
234 {
235         if ((strcmp(str, "=0") != 0 && strcmp(str, "=off") != 0))
236                 tracepoint_printk = 1;
237         return 1;
238 }
239 __setup("tp_printk", set_tracepoint_printk);
240
241 unsigned long long ns2usecs(u64 nsec)
242 {
243         nsec += 500;
244         do_div(nsec, 1000);
245         return nsec;
246 }
247
248 /* trace_flags holds trace_options default values */
249 #define TRACE_DEFAULT_FLAGS                                             \
250         (FUNCTION_DEFAULT_FLAGS |                                       \
251          TRACE_ITER_PRINT_PARENT | TRACE_ITER_PRINTK |                  \
252          TRACE_ITER_ANNOTATE | TRACE_ITER_CONTEXT_INFO |                \
253          TRACE_ITER_RECORD_CMD | TRACE_ITER_OVERWRITE |                 \
254          TRACE_ITER_IRQ_INFO | TRACE_ITER_MARKERS)
255
256 /* trace_options that are only supported by global_trace */
257 #define TOP_LEVEL_TRACE_FLAGS (TRACE_ITER_PRINTK |                      \
258                TRACE_ITER_PRINTK_MSGONLY | TRACE_ITER_RECORD_CMD)
259
260 /* trace_flags that are default zero for instances */
261 #define ZEROED_TRACE_FLAGS \
262         (TRACE_ITER_EVENT_FORK | TRACE_ITER_FUNC_FORK)
263
264 /*
265  * The global_trace is the descriptor that holds the top-level tracing
266  * buffers for the live tracing.
267  */
268 static struct trace_array global_trace = {
269         .trace_flags = TRACE_DEFAULT_FLAGS,
270 };
271
272 LIST_HEAD(ftrace_trace_arrays);
273
274 int trace_array_get(struct trace_array *this_tr)
275 {
276         struct trace_array *tr;
277         int ret = -ENODEV;
278
279         mutex_lock(&trace_types_lock);
280         list_for_each_entry(tr, &ftrace_trace_arrays, list) {
281                 if (tr == this_tr) {
282                         tr->ref++;
283                         ret = 0;
284                         break;
285                 }
286         }
287         mutex_unlock(&trace_types_lock);
288
289         return ret;
290 }
291
292 static void __trace_array_put(struct trace_array *this_tr)
293 {
294         WARN_ON(!this_tr->ref);
295         this_tr->ref--;
296 }
297
298 void trace_array_put(struct trace_array *this_tr)
299 {
300         mutex_lock(&trace_types_lock);
301         __trace_array_put(this_tr);
302         mutex_unlock(&trace_types_lock);
303 }
304
305 int call_filter_check_discard(struct trace_event_call *call, void *rec,
306                               struct ring_buffer *buffer,
307                               struct ring_buffer_event *event)
308 {
309         if (unlikely(call->flags & TRACE_EVENT_FL_FILTERED) &&
310             !filter_match_preds(call->filter, rec)) {
311                 __trace_event_discard_commit(buffer, event);
312                 return 1;
313         }
314
315         return 0;
316 }
317
318 void trace_free_pid_list(struct trace_pid_list *pid_list)
319 {
320         vfree(pid_list->pids);
321         kfree(pid_list);
322 }
323
324 /**
325  * trace_find_filtered_pid - check if a pid exists in a filtered_pid list
326  * @filtered_pids: The list of pids to check
327  * @search_pid: The PID to find in @filtered_pids
328  *
329  * Returns true if @search_pid is fonud in @filtered_pids, and false otherwis.
330  */
331 bool
332 trace_find_filtered_pid(struct trace_pid_list *filtered_pids, pid_t search_pid)
333 {
334         /*
335          * If pid_max changed after filtered_pids was created, we
336          * by default ignore all pids greater than the previous pid_max.
337          */
338         if (search_pid >= filtered_pids->pid_max)
339                 return false;
340
341         return test_bit(search_pid, filtered_pids->pids);
342 }
343
344 /**
345  * trace_ignore_this_task - should a task be ignored for tracing
346  * @filtered_pids: The list of pids to check
347  * @task: The task that should be ignored if not filtered
348  *
349  * Checks if @task should be traced or not from @filtered_pids.
350  * Returns true if @task should *NOT* be traced.
351  * Returns false if @task should be traced.
352  */
353 bool
354 trace_ignore_this_task(struct trace_pid_list *filtered_pids, struct task_struct *task)
355 {
356         /*
357          * Return false, because if filtered_pids does not exist,
358          * all pids are good to trace.
359          */
360         if (!filtered_pids)
361                 return false;
362
363         return !trace_find_filtered_pid(filtered_pids, task->pid);
364 }
365
366 /**
367  * trace_pid_filter_add_remove_task - Add or remove a task from a pid_list
368  * @pid_list: The list to modify
369  * @self: The current task for fork or NULL for exit
370  * @task: The task to add or remove
371  *
372  * If adding a task, if @self is defined, the task is only added if @self
373  * is also included in @pid_list. This happens on fork and tasks should
374  * only be added when the parent is listed. If @self is NULL, then the
375  * @task pid will be removed from the list, which would happen on exit
376  * of a task.
377  */
378 void trace_filter_add_remove_task(struct trace_pid_list *pid_list,
379                                   struct task_struct *self,
380                                   struct task_struct *task)
381 {
382         if (!pid_list)
383                 return;
384
385         /* For forks, we only add if the forking task is listed */
386         if (self) {
387                 if (!trace_find_filtered_pid(pid_list, self->pid))
388                         return;
389         }
390
391         /* Sorry, but we don't support pid_max changing after setting */
392         if (task->pid >= pid_list->pid_max)
393                 return;
394
395         /* "self" is set for forks, and NULL for exits */
396         if (self)
397                 set_bit(task->pid, pid_list->pids);
398         else
399                 clear_bit(task->pid, pid_list->pids);
400 }
401
402 /**
403  * trace_pid_next - Used for seq_file to get to the next pid of a pid_list
404  * @pid_list: The pid list to show
405  * @v: The last pid that was shown (+1 the actual pid to let zero be displayed)
406  * @pos: The position of the file
407  *
408  * This is used by the seq_file "next" operation to iterate the pids
409  * listed in a trace_pid_list structure.
410  *
411  * Returns the pid+1 as we want to display pid of zero, but NULL would
412  * stop the iteration.
413  */
414 void *trace_pid_next(struct trace_pid_list *pid_list, void *v, loff_t *pos)
415 {
416         unsigned long pid = (unsigned long)v;
417
418         (*pos)++;
419
420         /* pid already is +1 of the actual prevous bit */
421         pid = find_next_bit(pid_list->pids, pid_list->pid_max, pid);
422
423         /* Return pid + 1 to allow zero to be represented */
424         if (pid < pid_list->pid_max)
425                 return (void *)(pid + 1);
426
427         return NULL;
428 }
429
430 /**
431  * trace_pid_start - Used for seq_file to start reading pid lists
432  * @pid_list: The pid list to show
433  * @pos: The position of the file
434  *
435  * This is used by seq_file "start" operation to start the iteration
436  * of listing pids.
437  *
438  * Returns the pid+1 as we want to display pid of zero, but NULL would
439  * stop the iteration.
440  */
441 void *trace_pid_start(struct trace_pid_list *pid_list, loff_t *pos)
442 {
443         unsigned long pid;
444         loff_t l = 0;
445
446         pid = find_first_bit(pid_list->pids, pid_list->pid_max);
447         if (pid >= pid_list->pid_max)
448                 return NULL;
449
450         /* Return pid + 1 so that zero can be the exit value */
451         for (pid++; pid && l < *pos;
452              pid = (unsigned long)trace_pid_next(pid_list, (void *)pid, &l))
453                 ;
454         return (void *)pid;
455 }
456
457 /**
458  * trace_pid_show - show the current pid in seq_file processing
459  * @m: The seq_file structure to write into
460  * @v: A void pointer of the pid (+1) value to display
461  *
462  * Can be directly used by seq_file operations to display the current
463  * pid value.
464  */
465 int trace_pid_show(struct seq_file *m, void *v)
466 {
467         unsigned long pid = (unsigned long)v - 1;
468
469         seq_printf(m, "%lu\n", pid);
470         return 0;
471 }
472
473 /* 128 should be much more than enough */
474 #define PID_BUF_SIZE            127
475
476 int trace_pid_write(struct trace_pid_list *filtered_pids,
477                     struct trace_pid_list **new_pid_list,
478                     const char __user *ubuf, size_t cnt)
479 {
480         struct trace_pid_list *pid_list;
481         struct trace_parser parser;
482         unsigned long val;
483         int nr_pids = 0;
484         ssize_t read = 0;
485         ssize_t ret = 0;
486         loff_t pos;
487         pid_t pid;
488
489         if (trace_parser_get_init(&parser, PID_BUF_SIZE + 1))
490                 return -ENOMEM;
491
492         /*
493          * Always recreate a new array. The write is an all or nothing
494          * operation. Always create a new array when adding new pids by
495          * the user. If the operation fails, then the current list is
496          * not modified.
497          */
498         pid_list = kmalloc(sizeof(*pid_list), GFP_KERNEL);
499         if (!pid_list)
500                 return -ENOMEM;
501
502         pid_list->pid_max = READ_ONCE(pid_max);
503
504         /* Only truncating will shrink pid_max */
505         if (filtered_pids && filtered_pids->pid_max > pid_list->pid_max)
506                 pid_list->pid_max = filtered_pids->pid_max;
507
508         pid_list->pids = vzalloc((pid_list->pid_max + 7) >> 3);
509         if (!pid_list->pids) {
510                 kfree(pid_list);
511                 return -ENOMEM;
512         }
513
514         if (filtered_pids) {
515                 /* copy the current bits to the new max */
516                 for_each_set_bit(pid, filtered_pids->pids,
517                                  filtered_pids->pid_max) {
518                         set_bit(pid, pid_list->pids);
519                         nr_pids++;
520                 }
521         }
522
523         while (cnt > 0) {
524
525                 pos = 0;
526
527                 ret = trace_get_user(&parser, ubuf, cnt, &pos);
528                 if (ret < 0 || !trace_parser_loaded(&parser))
529                         break;
530
531                 read += ret;
532                 ubuf += ret;
533                 cnt -= ret;
534
535                 ret = -EINVAL;
536                 if (kstrtoul(parser.buffer, 0, &val))
537                         break;
538                 if (val >= pid_list->pid_max)
539                         break;
540
541                 pid = (pid_t)val;
542
543                 set_bit(pid, pid_list->pids);
544                 nr_pids++;
545
546                 trace_parser_clear(&parser);
547                 ret = 0;
548         }
549         trace_parser_put(&parser);
550
551         if (ret < 0) {
552                 trace_free_pid_list(pid_list);
553                 return ret;
554         }
555
556         if (!nr_pids) {
557                 /* Cleared the list of pids */
558                 trace_free_pid_list(pid_list);
559                 read = ret;
560                 pid_list = NULL;
561         }
562
563         *new_pid_list = pid_list;
564
565         return read;
566 }
567
568 static u64 buffer_ftrace_now(struct trace_buffer *buf, int cpu)
569 {
570         u64 ts;
571
572         /* Early boot up does not have a buffer yet */
573         if (!buf->buffer)
574                 return trace_clock_local();
575
576         ts = ring_buffer_time_stamp(buf->buffer, cpu);
577         ring_buffer_normalize_time_stamp(buf->buffer, cpu, &ts);
578
579         return ts;
580 }
581
582 u64 ftrace_now(int cpu)
583 {
584         return buffer_ftrace_now(&global_trace.trace_buffer, cpu);
585 }
586
587 /**
588  * tracing_is_enabled - Show if global_trace has been disabled
589  *
590  * Shows if the global trace has been enabled or not. It uses the
591  * mirror flag "buffer_disabled" to be used in fast paths such as for
592  * the irqsoff tracer. But it may be inaccurate due to races. If you
593  * need to know the accurate state, use tracing_is_on() which is a little
594  * slower, but accurate.
595  */
596 int tracing_is_enabled(void)
597 {
598         /*
599          * For quick access (irqsoff uses this in fast path), just
600          * return the mirror variable of the state of the ring buffer.
601          * It's a little racy, but we don't really care.
602          */
603         smp_rmb();
604         return !global_trace.buffer_disabled;
605 }
606
607 /*
608  * trace_buf_size is the size in bytes that is allocated
609  * for a buffer. Note, the number of bytes is always rounded
610  * to page size.
611  *
612  * This number is purposely set to a low number of 16384.
613  * If the dump on oops happens, it will be much appreciated
614  * to not have to wait for all that output. Anyway this can be
615  * boot time and run time configurable.
616  */
617 #define TRACE_BUF_SIZE_DEFAULT  1441792UL /* 16384 * 88 (sizeof(entry)) */
618
619 static unsigned long            trace_buf_size = TRACE_BUF_SIZE_DEFAULT;
620
621 /* trace_types holds a link list of available tracers. */
622 static struct tracer            *trace_types __read_mostly;
623
624 /*
625  * trace_types_lock is used to protect the trace_types list.
626  */
627 DEFINE_MUTEX(trace_types_lock);
628
629 /*
630  * serialize the access of the ring buffer
631  *
632  * ring buffer serializes readers, but it is low level protection.
633  * The validity of the events (which returns by ring_buffer_peek() ..etc)
634  * are not protected by ring buffer.
635  *
636  * The content of events may become garbage if we allow other process consumes
637  * these events concurrently:
638  *   A) the page of the consumed events may become a normal page
639  *      (not reader page) in ring buffer, and this page will be rewrited
640  *      by events producer.
641  *   B) The page of the consumed events may become a page for splice_read,
642  *      and this page will be returned to system.
643  *
644  * These primitives allow multi process access to different cpu ring buffer
645  * concurrently.
646  *
647  * These primitives don't distinguish read-only and read-consume access.
648  * Multi read-only access are also serialized.
649  */
650
651 #ifdef CONFIG_SMP
652 static DECLARE_RWSEM(all_cpu_access_lock);
653 static DEFINE_PER_CPU(struct mutex, cpu_access_lock);
654
655 static inline void trace_access_lock(int cpu)
656 {
657         if (cpu == RING_BUFFER_ALL_CPUS) {
658                 /* gain it for accessing the whole ring buffer. */
659                 down_write(&all_cpu_access_lock);
660         } else {
661                 /* gain it for accessing a cpu ring buffer. */
662
663                 /* Firstly block other trace_access_lock(RING_BUFFER_ALL_CPUS). */
664                 down_read(&all_cpu_access_lock);
665
666                 /* Secondly block other access to this @cpu ring buffer. */
667                 mutex_lock(&per_cpu(cpu_access_lock, cpu));
668         }
669 }
670
671 static inline void trace_access_unlock(int cpu)
672 {
673         if (cpu == RING_BUFFER_ALL_CPUS) {
674                 up_write(&all_cpu_access_lock);
675         } else {
676                 mutex_unlock(&per_cpu(cpu_access_lock, cpu));
677                 up_read(&all_cpu_access_lock);
678         }
679 }
680
681 static inline void trace_access_lock_init(void)
682 {
683         int cpu;
684
685         for_each_possible_cpu(cpu)
686                 mutex_init(&per_cpu(cpu_access_lock, cpu));
687 }
688
689 #else
690
691 static DEFINE_MUTEX(access_lock);
692
693 static inline void trace_access_lock(int cpu)
694 {
695         (void)cpu;
696         mutex_lock(&access_lock);
697 }
698
699 static inline void trace_access_unlock(int cpu)
700 {
701         (void)cpu;
702         mutex_unlock(&access_lock);
703 }
704
705 static inline void trace_access_lock_init(void)
706 {
707 }
708
709 #endif
710
711 #ifdef CONFIG_STACKTRACE
712 static void __ftrace_trace_stack(struct ring_buffer *buffer,
713                                  unsigned long flags,
714                                  int skip, int pc, struct pt_regs *regs);
715 static inline void ftrace_trace_stack(struct trace_array *tr,
716                                       struct ring_buffer *buffer,
717                                       unsigned long flags,
718                                       int skip, int pc, struct pt_regs *regs);
719
720 #else
721 static inline void __ftrace_trace_stack(struct ring_buffer *buffer,
722                                         unsigned long flags,
723                                         int skip, int pc, struct pt_regs *regs)
724 {
725 }
726 static inline void ftrace_trace_stack(struct trace_array *tr,
727                                       struct ring_buffer *buffer,
728                                       unsigned long flags,
729                                       int skip, int pc, struct pt_regs *regs)
730 {
731 }
732
733 #endif
734
735 static __always_inline void
736 trace_event_setup(struct ring_buffer_event *event,
737                   int type, unsigned long flags, int pc)
738 {
739         struct trace_entry *ent = ring_buffer_event_data(event);
740
741         tracing_generic_entry_update(ent, flags, pc);
742         ent->type = type;
743 }
744
745 static __always_inline struct ring_buffer_event *
746 __trace_buffer_lock_reserve(struct ring_buffer *buffer,
747                           int type,
748                           unsigned long len,
749                           unsigned long flags, int pc)
750 {
751         struct ring_buffer_event *event;
752
753         event = ring_buffer_lock_reserve(buffer, len);
754         if (event != NULL)
755                 trace_event_setup(event, type, flags, pc);
756
757         return event;
758 }
759
760 void tracer_tracing_on(struct trace_array *tr)
761 {
762         if (tr->trace_buffer.buffer)
763                 ring_buffer_record_on(tr->trace_buffer.buffer);
764         /*
765          * This flag is looked at when buffers haven't been allocated
766          * yet, or by some tracers (like irqsoff), that just want to
767          * know if the ring buffer has been disabled, but it can handle
768          * races of where it gets disabled but we still do a record.
769          * As the check is in the fast path of the tracers, it is more
770          * important to be fast than accurate.
771          */
772         tr->buffer_disabled = 0;
773         /* Make the flag seen by readers */
774         smp_wmb();
775 }
776
777 /**
778  * tracing_on - enable tracing buffers
779  *
780  * This function enables tracing buffers that may have been
781  * disabled with tracing_off.
782  */
783 void tracing_on(void)
784 {
785         tracer_tracing_on(&global_trace);
786 }
787 EXPORT_SYMBOL_GPL(tracing_on);
788
789
790 static __always_inline void
791 __buffer_unlock_commit(struct ring_buffer *buffer, struct ring_buffer_event *event)
792 {
793         __this_cpu_write(trace_taskinfo_save, true);
794
795         /* If this is the temp buffer, we need to commit fully */
796         if (this_cpu_read(trace_buffered_event) == event) {
797                 /* Length is in event->array[0] */
798                 ring_buffer_write(buffer, event->array[0], &event->array[1]);
799                 /* Release the temp buffer */
800                 this_cpu_dec(trace_buffered_event_cnt);
801         } else
802                 ring_buffer_unlock_commit(buffer, event);
803 }
804
805 /**
806  * __trace_puts - write a constant string into the trace buffer.
807  * @ip:    The address of the caller
808  * @str:   The constant string to write
809  * @size:  The size of the string.
810  */
811 int __trace_puts(unsigned long ip, const char *str, int size)
812 {
813         struct ring_buffer_event *event;
814         struct ring_buffer *buffer;
815         struct print_entry *entry;
816         unsigned long irq_flags;
817         int alloc;
818         int pc;
819
820         if (!(global_trace.trace_flags & TRACE_ITER_PRINTK))
821                 return 0;
822
823         pc = preempt_count();
824
825         if (unlikely(tracing_selftest_running || tracing_disabled))
826                 return 0;
827
828         alloc = sizeof(*entry) + size + 2; /* possible \n added */
829
830         local_save_flags(irq_flags);
831         buffer = global_trace.trace_buffer.buffer;
832         event = __trace_buffer_lock_reserve(buffer, TRACE_PRINT, alloc, 
833                                             irq_flags, pc);
834         if (!event)
835                 return 0;
836
837         entry = ring_buffer_event_data(event);
838         entry->ip = ip;
839
840         memcpy(&entry->buf, str, size);
841
842         /* Add a newline if necessary */
843         if (entry->buf[size - 1] != '\n') {
844                 entry->buf[size] = '\n';
845                 entry->buf[size + 1] = '\0';
846         } else
847                 entry->buf[size] = '\0';
848
849         __buffer_unlock_commit(buffer, event);
850         ftrace_trace_stack(&global_trace, buffer, irq_flags, 4, pc, NULL);
851
852         return size;
853 }
854 EXPORT_SYMBOL_GPL(__trace_puts);
855
856 /**
857  * __trace_bputs - write the pointer to a constant string into trace buffer
858  * @ip:    The address of the caller
859  * @str:   The constant string to write to the buffer to
860  */
861 int __trace_bputs(unsigned long ip, const char *str)
862 {
863         struct ring_buffer_event *event;
864         struct ring_buffer *buffer;
865         struct bputs_entry *entry;
866         unsigned long irq_flags;
867         int size = sizeof(struct bputs_entry);
868         int pc;
869
870         if (!(global_trace.trace_flags & TRACE_ITER_PRINTK))
871                 return 0;
872
873         pc = preempt_count();
874
875         if (unlikely(tracing_selftest_running || tracing_disabled))
876                 return 0;
877
878         local_save_flags(irq_flags);
879         buffer = global_trace.trace_buffer.buffer;
880         event = __trace_buffer_lock_reserve(buffer, TRACE_BPUTS, size,
881                                             irq_flags, pc);
882         if (!event)
883                 return 0;
884
885         entry = ring_buffer_event_data(event);
886         entry->ip                       = ip;
887         entry->str                      = str;
888
889         __buffer_unlock_commit(buffer, event);
890         ftrace_trace_stack(&global_trace, buffer, irq_flags, 4, pc, NULL);
891
892         return 1;
893 }
894 EXPORT_SYMBOL_GPL(__trace_bputs);
895
896 #ifdef CONFIG_TRACER_SNAPSHOT
897 void tracing_snapshot_instance_cond(struct trace_array *tr, void *cond_data)
898 {
899         struct tracer *tracer = tr->current_trace;
900         unsigned long flags;
901
902         if (in_nmi()) {
903                 internal_trace_puts("*** SNAPSHOT CALLED FROM NMI CONTEXT ***\n");
904                 internal_trace_puts("*** snapshot is being ignored        ***\n");
905                 return;
906         }
907
908         if (!tr->allocated_snapshot) {
909                 internal_trace_puts("*** SNAPSHOT NOT ALLOCATED ***\n");
910                 internal_trace_puts("*** stopping trace here!   ***\n");
911                 tracing_off();
912                 return;
913         }
914
915         /* Note, snapshot can not be used when the tracer uses it */
916         if (tracer->use_max_tr) {
917                 internal_trace_puts("*** LATENCY TRACER ACTIVE ***\n");
918                 internal_trace_puts("*** Can not use snapshot (sorry) ***\n");
919                 return;
920         }
921
922         local_irq_save(flags);
923         update_max_tr(tr, current, smp_processor_id(), cond_data);
924         local_irq_restore(flags);
925 }
926
927 void tracing_snapshot_instance(struct trace_array *tr)
928 {
929         tracing_snapshot_instance_cond(tr, NULL);
930 }
931
932 /**
933  * tracing_snapshot - take a snapshot of the current buffer.
934  *
935  * This causes a swap between the snapshot buffer and the current live
936  * tracing buffer. You can use this to take snapshots of the live
937  * trace when some condition is triggered, but continue to trace.
938  *
939  * Note, make sure to allocate the snapshot with either
940  * a tracing_snapshot_alloc(), or by doing it manually
941  * with: echo 1 > /sys/kernel/debug/tracing/snapshot
942  *
943  * If the snapshot buffer is not allocated, it will stop tracing.
944  * Basically making a permanent snapshot.
945  */
946 void tracing_snapshot(void)
947 {
948         struct trace_array *tr = &global_trace;
949
950         tracing_snapshot_instance(tr);
951 }
952 EXPORT_SYMBOL_GPL(tracing_snapshot);
953
954 /**
955  * tracing_snapshot_cond - conditionally take a snapshot of the current buffer.
956  * @tr:         The tracing instance to snapshot
957  * @cond_data:  The data to be tested conditionally, and possibly saved
958  *
959  * This is the same as tracing_snapshot() except that the snapshot is
960  * conditional - the snapshot will only happen if the
961  * cond_snapshot.update() implementation receiving the cond_data
962  * returns true, which means that the trace array's cond_snapshot
963  * update() operation used the cond_data to determine whether the
964  * snapshot should be taken, and if it was, presumably saved it along
965  * with the snapshot.
966  */
967 void tracing_snapshot_cond(struct trace_array *tr, void *cond_data)
968 {
969         tracing_snapshot_instance_cond(tr, cond_data);
970 }
971 EXPORT_SYMBOL_GPL(tracing_snapshot_cond);
972
973 /**
974  * tracing_snapshot_cond_data - get the user data associated with a snapshot
975  * @tr:         The tracing instance
976  *
977  * When the user enables a conditional snapshot using
978  * tracing_snapshot_cond_enable(), the user-defined cond_data is saved
979  * with the snapshot.  This accessor is used to retrieve it.
980  *
981  * Should not be called from cond_snapshot.update(), since it takes
982  * the tr->max_lock lock, which the code calling
983  * cond_snapshot.update() has already done.
984  *
985  * Returns the cond_data associated with the trace array's snapshot.
986  */
987 void *tracing_cond_snapshot_data(struct trace_array *tr)
988 {
989         void *cond_data = NULL;
990
991         arch_spin_lock(&tr->max_lock);
992
993         if (tr->cond_snapshot)
994                 cond_data = tr->cond_snapshot->cond_data;
995
996         arch_spin_unlock(&tr->max_lock);
997
998         return cond_data;
999 }
1000 EXPORT_SYMBOL_GPL(tracing_cond_snapshot_data);
1001
1002 static int resize_buffer_duplicate_size(struct trace_buffer *trace_buf,
1003                                         struct trace_buffer *size_buf, int cpu_id);
1004 static void set_buffer_entries(struct trace_buffer *buf, unsigned long val);
1005
1006 int tracing_alloc_snapshot_instance(struct trace_array *tr)
1007 {
1008         int ret;
1009
1010         if (!tr->allocated_snapshot) {
1011
1012                 /* allocate spare buffer */
1013                 ret = resize_buffer_duplicate_size(&tr->max_buffer,
1014                                    &tr->trace_buffer, RING_BUFFER_ALL_CPUS);
1015                 if (ret < 0)
1016                         return ret;
1017
1018                 tr->allocated_snapshot = true;
1019         }
1020
1021         return 0;
1022 }
1023
1024 static void free_snapshot(struct trace_array *tr)
1025 {
1026         /*
1027          * We don't free the ring buffer. instead, resize it because
1028          * The max_tr ring buffer has some state (e.g. ring->clock) and
1029          * we want preserve it.
1030          */
1031         ring_buffer_resize(tr->max_buffer.buffer, 1, RING_BUFFER_ALL_CPUS);
1032         set_buffer_entries(&tr->max_buffer, 1);
1033         tracing_reset_online_cpus(&tr->max_buffer);
1034         tr->allocated_snapshot = false;
1035 }
1036
1037 /**
1038  * tracing_alloc_snapshot - allocate snapshot buffer.
1039  *
1040  * This only allocates the snapshot buffer if it isn't already
1041  * allocated - it doesn't also take a snapshot.
1042  *
1043  * This is meant to be used in cases where the snapshot buffer needs
1044  * to be set up for events that can't sleep but need to be able to
1045  * trigger a snapshot.
1046  */
1047 int tracing_alloc_snapshot(void)
1048 {
1049         struct trace_array *tr = &global_trace;
1050         int ret;
1051
1052         ret = tracing_alloc_snapshot_instance(tr);
1053         WARN_ON(ret < 0);
1054
1055         return ret;
1056 }
1057 EXPORT_SYMBOL_GPL(tracing_alloc_snapshot);
1058
1059 /**
1060  * tracing_snapshot_alloc - allocate and take a snapshot of the current buffer.
1061  *
1062  * This is similar to tracing_snapshot(), but it will allocate the
1063  * snapshot buffer if it isn't already allocated. Use this only
1064  * where it is safe to sleep, as the allocation may sleep.
1065  *
1066  * This causes a swap between the snapshot buffer and the current live
1067  * tracing buffer. You can use this to take snapshots of the live
1068  * trace when some condition is triggered, but continue to trace.
1069  */
1070 void tracing_snapshot_alloc(void)
1071 {
1072         int ret;
1073
1074         ret = tracing_alloc_snapshot();
1075         if (ret < 0)
1076                 return;
1077
1078         tracing_snapshot();
1079 }
1080 EXPORT_SYMBOL_GPL(tracing_snapshot_alloc);
1081
1082 /**
1083  * tracing_snapshot_cond_enable - enable conditional snapshot for an instance
1084  * @tr:         The tracing instance
1085  * @cond_data:  User data to associate with the snapshot
1086  * @update:     Implementation of the cond_snapshot update function
1087  *
1088  * Check whether the conditional snapshot for the given instance has
1089  * already been enabled, or if the current tracer is already using a
1090  * snapshot; if so, return -EBUSY, else create a cond_snapshot and
1091  * save the cond_data and update function inside.
1092  *
1093  * Returns 0 if successful, error otherwise.
1094  */
1095 int tracing_snapshot_cond_enable(struct trace_array *tr, void *cond_data,
1096                                  cond_update_fn_t update)
1097 {
1098         struct cond_snapshot *cond_snapshot;
1099         int ret = 0;
1100
1101         cond_snapshot = kzalloc(sizeof(*cond_snapshot), GFP_KERNEL);
1102         if (!cond_snapshot)
1103                 return -ENOMEM;
1104
1105         cond_snapshot->cond_data = cond_data;
1106         cond_snapshot->update = update;
1107
1108         mutex_lock(&trace_types_lock);
1109
1110         ret = tracing_alloc_snapshot_instance(tr);
1111         if (ret)
1112                 goto fail_unlock;
1113
1114         if (tr->current_trace->use_max_tr) {
1115                 ret = -EBUSY;
1116                 goto fail_unlock;
1117         }
1118
1119         /*
1120          * The cond_snapshot can only change to NULL without the
1121          * trace_types_lock. We don't care if we race with it going
1122          * to NULL, but we want to make sure that it's not set to
1123          * something other than NULL when we get here, which we can
1124          * do safely with only holding the trace_types_lock and not
1125          * having to take the max_lock.
1126          */
1127         if (tr->cond_snapshot) {
1128                 ret = -EBUSY;
1129                 goto fail_unlock;
1130         }
1131
1132         arch_spin_lock(&tr->max_lock);
1133         tr->cond_snapshot = cond_snapshot;
1134         arch_spin_unlock(&tr->max_lock);
1135
1136         mutex_unlock(&trace_types_lock);
1137
1138         return ret;
1139
1140  fail_unlock:
1141         mutex_unlock(&trace_types_lock);
1142         kfree(cond_snapshot);
1143         return ret;
1144 }
1145 EXPORT_SYMBOL_GPL(tracing_snapshot_cond_enable);
1146
1147 /**
1148  * tracing_snapshot_cond_disable - disable conditional snapshot for an instance
1149  * @tr:         The tracing instance
1150  *
1151  * Check whether the conditional snapshot for the given instance is
1152  * enabled; if so, free the cond_snapshot associated with it,
1153  * otherwise return -EINVAL.
1154  *
1155  * Returns 0 if successful, error otherwise.
1156  */
1157 int tracing_snapshot_cond_disable(struct trace_array *tr)
1158 {
1159         int ret = 0;
1160
1161         arch_spin_lock(&tr->max_lock);
1162
1163         if (!tr->cond_snapshot)
1164                 ret = -EINVAL;
1165         else {
1166                 kfree(tr->cond_snapshot);
1167                 tr->cond_snapshot = NULL;
1168         }
1169
1170         arch_spin_unlock(&tr->max_lock);
1171
1172         return ret;
1173 }
1174 EXPORT_SYMBOL_GPL(tracing_snapshot_cond_disable);
1175 #else
1176 void tracing_snapshot(void)
1177 {
1178         WARN_ONCE(1, "Snapshot feature not enabled, but internal snapshot used");
1179 }
1180 EXPORT_SYMBOL_GPL(tracing_snapshot);
1181 void tracing_snapshot_cond(struct trace_array *tr, void *cond_data)
1182 {
1183         WARN_ONCE(1, "Snapshot feature not enabled, but internal conditional snapshot used");
1184 }
1185 EXPORT_SYMBOL_GPL(tracing_snapshot_cond);
1186 int tracing_alloc_snapshot(void)
1187 {
1188         WARN_ONCE(1, "Snapshot feature not enabled, but snapshot allocation used");
1189         return -ENODEV;
1190 }
1191 EXPORT_SYMBOL_GPL(tracing_alloc_snapshot);
1192 void tracing_snapshot_alloc(void)
1193 {
1194         /* Give warning */
1195         tracing_snapshot();
1196 }
1197 EXPORT_SYMBOL_GPL(tracing_snapshot_alloc);
1198 void *tracing_cond_snapshot_data(struct trace_array *tr)
1199 {
1200         return NULL;
1201 }
1202 EXPORT_SYMBOL_GPL(tracing_cond_snapshot_data);
1203 int tracing_snapshot_cond_enable(struct trace_array *tr, void *cond_data, cond_update_fn_t update)
1204 {
1205         return -ENODEV;
1206 }
1207 EXPORT_SYMBOL_GPL(tracing_snapshot_cond_enable);
1208 int tracing_snapshot_cond_disable(struct trace_array *tr)
1209 {
1210         return false;
1211 }
1212 EXPORT_SYMBOL_GPL(tracing_snapshot_cond_disable);
1213 #endif /* CONFIG_TRACER_SNAPSHOT */
1214
1215 void tracer_tracing_off(struct trace_array *tr)
1216 {
1217         if (tr->trace_buffer.buffer)
1218                 ring_buffer_record_off(tr->trace_buffer.buffer);
1219         /*
1220          * This flag is looked at when buffers haven't been allocated
1221          * yet, or by some tracers (like irqsoff), that just want to
1222          * know if the ring buffer has been disabled, but it can handle
1223          * races of where it gets disabled but we still do a record.
1224          * As the check is in the fast path of the tracers, it is more
1225          * important to be fast than accurate.
1226          */
1227         tr->buffer_disabled = 1;
1228         /* Make the flag seen by readers */
1229         smp_wmb();
1230 }
1231
1232 /**
1233  * tracing_off - turn off tracing buffers
1234  *
1235  * This function stops the tracing buffers from recording data.
1236  * It does not disable any overhead the tracers themselves may
1237  * be causing. This function simply causes all recording to
1238  * the ring buffers to fail.
1239  */
1240 void tracing_off(void)
1241 {
1242         tracer_tracing_off(&global_trace);
1243 }
1244 EXPORT_SYMBOL_GPL(tracing_off);
1245
1246 void disable_trace_on_warning(void)
1247 {
1248         if (__disable_trace_on_warning)
1249                 tracing_off();
1250 }
1251
1252 /**
1253  * tracer_tracing_is_on - show real state of ring buffer enabled
1254  * @tr : the trace array to know if ring buffer is enabled
1255  *
1256  * Shows real state of the ring buffer if it is enabled or not.
1257  */
1258 bool tracer_tracing_is_on(struct trace_array *tr)
1259 {
1260         if (tr->trace_buffer.buffer)
1261                 return ring_buffer_record_is_on(tr->trace_buffer.buffer);
1262         return !tr->buffer_disabled;
1263 }
1264
1265 /**
1266  * tracing_is_on - show state of ring buffers enabled
1267  */
1268 int tracing_is_on(void)
1269 {
1270         return tracer_tracing_is_on(&global_trace);
1271 }
1272 EXPORT_SYMBOL_GPL(tracing_is_on);
1273
1274 static int __init set_buf_size(char *str)
1275 {
1276         unsigned long buf_size;
1277
1278         if (!str)
1279                 return 0;
1280         buf_size = memparse(str, &str);
1281         /* nr_entries can not be zero */
1282         if (buf_size == 0)
1283                 return 0;
1284         trace_buf_size = buf_size;
1285         return 1;
1286 }
1287 __setup("trace_buf_size=", set_buf_size);
1288
1289 static int __init set_tracing_thresh(char *str)
1290 {
1291         unsigned long threshold;
1292         int ret;
1293
1294         if (!str)
1295                 return 0;
1296         ret = kstrtoul(str, 0, &threshold);
1297         if (ret < 0)
1298                 return 0;
1299         tracing_thresh = threshold * 1000;
1300         return 1;
1301 }
1302 __setup("tracing_thresh=", set_tracing_thresh);
1303
1304 unsigned long nsecs_to_usecs(unsigned long nsecs)
1305 {
1306         return nsecs / 1000;
1307 }
1308
1309 /*
1310  * TRACE_FLAGS is defined as a tuple matching bit masks with strings.
1311  * It uses C(a, b) where 'a' is the eval (enum) name and 'b' is the string that
1312  * matches it. By defining "C(a, b) b", TRACE_FLAGS becomes a list
1313  * of strings in the order that the evals (enum) were defined.
1314  */
1315 #undef C
1316 #define C(a, b) b
1317
1318 /* These must match the bit postions in trace_iterator_flags */
1319 static const char *trace_options[] = {
1320         TRACE_FLAGS
1321         NULL
1322 };
1323
1324 static struct {
1325         u64 (*func)(void);
1326         const char *name;
1327         int in_ns;              /* is this clock in nanoseconds? */
1328 } trace_clocks[] = {
1329         { trace_clock_local,            "local",        1 },
1330         { trace_clock_global,           "global",       1 },
1331         { trace_clock_counter,          "counter",      0 },
1332         { trace_clock_jiffies,          "uptime",       0 },
1333         { trace_clock,                  "perf",         1 },
1334         { ktime_get_mono_fast_ns,       "mono",         1 },
1335         { ktime_get_raw_fast_ns,        "mono_raw",     1 },
1336         { ktime_get_boot_fast_ns,       "boot",         1 },
1337         ARCH_TRACE_CLOCKS
1338 };
1339
1340 bool trace_clock_in_ns(struct trace_array *tr)
1341 {
1342         if (trace_clocks[tr->clock_id].in_ns)
1343                 return true;
1344
1345         return false;
1346 }
1347
1348 /*
1349  * trace_parser_get_init - gets the buffer for trace parser
1350  */
1351 int trace_parser_get_init(struct trace_parser *parser, int size)
1352 {
1353         memset(parser, 0, sizeof(*parser));
1354
1355         parser->buffer = kmalloc(size, GFP_KERNEL);
1356         if (!parser->buffer)
1357                 return 1;
1358
1359         parser->size = size;
1360         return 0;
1361 }
1362
1363 /*
1364  * trace_parser_put - frees the buffer for trace parser
1365  */
1366 void trace_parser_put(struct trace_parser *parser)
1367 {
1368         kfree(parser->buffer);
1369         parser->buffer = NULL;
1370 }
1371
1372 /*
1373  * trace_get_user - reads the user input string separated by  space
1374  * (matched by isspace(ch))
1375  *
1376  * For each string found the 'struct trace_parser' is updated,
1377  * and the function returns.
1378  *
1379  * Returns number of bytes read.
1380  *
1381  * See kernel/trace/trace.h for 'struct trace_parser' details.
1382  */
1383 int trace_get_user(struct trace_parser *parser, const char __user *ubuf,
1384         size_t cnt, loff_t *ppos)
1385 {
1386         char ch;
1387         size_t read = 0;
1388         ssize_t ret;
1389
1390         if (!*ppos)
1391                 trace_parser_clear(parser);
1392
1393         ret = get_user(ch, ubuf++);
1394         if (ret)
1395                 goto out;
1396
1397         read++;
1398         cnt--;
1399
1400         /*
1401          * The parser is not finished with the last write,
1402          * continue reading the user input without skipping spaces.
1403          */
1404         if (!parser->cont) {
1405                 /* skip white space */
1406                 while (cnt && isspace(ch)) {
1407                         ret = get_user(ch, ubuf++);
1408                         if (ret)
1409                                 goto out;
1410                         read++;
1411                         cnt--;
1412                 }
1413
1414                 parser->idx = 0;
1415
1416                 /* only spaces were written */
1417                 if (isspace(ch) || !ch) {
1418                         *ppos += read;
1419                         ret = read;
1420                         goto out;
1421                 }
1422         }
1423
1424         /* read the non-space input */
1425         while (cnt && !isspace(ch) && ch) {
1426                 if (parser->idx < parser->size - 1)
1427                         parser->buffer[parser->idx++] = ch;
1428                 else {
1429                         ret = -EINVAL;
1430                         goto out;
1431                 }
1432                 ret = get_user(ch, ubuf++);
1433                 if (ret)
1434                         goto out;
1435                 read++;
1436                 cnt--;
1437         }
1438
1439         /* We either got finished input or we have to wait for another call. */
1440         if (isspace(ch) || !ch) {
1441                 parser->buffer[parser->idx] = 0;
1442                 parser->cont = false;
1443         } else if (parser->idx < parser->size - 1) {
1444                 parser->cont = true;
1445                 parser->buffer[parser->idx++] = ch;
1446                 /* Make sure the parsed string always terminates with '\0'. */
1447                 parser->buffer[parser->idx] = 0;
1448         } else {
1449                 ret = -EINVAL;
1450                 goto out;
1451         }
1452
1453         *ppos += read;
1454         ret = read;
1455
1456 out:
1457         return ret;
1458 }
1459
1460 /* TODO add a seq_buf_to_buffer() */
1461 static ssize_t trace_seq_to_buffer(struct trace_seq *s, void *buf, size_t cnt)
1462 {
1463         int len;
1464
1465         if (trace_seq_used(s) <= s->seq.readpos)
1466                 return -EBUSY;
1467
1468         len = trace_seq_used(s) - s->seq.readpos;
1469         if (cnt > len)
1470                 cnt = len;
1471         memcpy(buf, s->buffer + s->seq.readpos, cnt);
1472
1473         s->seq.readpos += cnt;
1474         return cnt;
1475 }
1476
1477 unsigned long __read_mostly     tracing_thresh;
1478
1479 #ifdef CONFIG_TRACER_MAX_TRACE
1480 /*
1481  * Copy the new maximum trace into the separate maximum-trace
1482  * structure. (this way the maximum trace is permanently saved,
1483  * for later retrieval via /sys/kernel/tracing/tracing_max_latency)
1484  */
1485 static void
1486 __update_max_tr(struct trace_array *tr, struct task_struct *tsk, int cpu)
1487 {
1488         struct trace_buffer *trace_buf = &tr->trace_buffer;
1489         struct trace_buffer *max_buf = &tr->max_buffer;
1490         struct trace_array_cpu *data = per_cpu_ptr(trace_buf->data, cpu);
1491         struct trace_array_cpu *max_data = per_cpu_ptr(max_buf->data, cpu);
1492
1493         max_buf->cpu = cpu;
1494         max_buf->time_start = data->preempt_timestamp;
1495
1496         max_data->saved_latency = tr->max_latency;
1497         max_data->critical_start = data->critical_start;
1498         max_data->critical_end = data->critical_end;
1499
1500         strncpy(max_data->comm, tsk->comm, TASK_COMM_LEN);
1501         max_data->pid = tsk->pid;
1502         /*
1503          * If tsk == current, then use current_uid(), as that does not use
1504          * RCU. The irq tracer can be called out of RCU scope.
1505          */
1506         if (tsk == current)
1507                 max_data->uid = current_uid();
1508         else
1509                 max_data->uid = task_uid(tsk);
1510
1511         max_data->nice = tsk->static_prio - 20 - MAX_RT_PRIO;
1512         max_data->policy = tsk->policy;
1513         max_data->rt_priority = tsk->rt_priority;
1514
1515         /* record this tasks comm */
1516         tracing_record_cmdline(tsk);
1517 }
1518
1519 /**
1520  * update_max_tr - snapshot all trace buffers from global_trace to max_tr
1521  * @tr: tracer
1522  * @tsk: the task with the latency
1523  * @cpu: The cpu that initiated the trace.
1524  * @cond_data: User data associated with a conditional snapshot
1525  *
1526  * Flip the buffers between the @tr and the max_tr and record information
1527  * about which task was the cause of this latency.
1528  */
1529 void
1530 update_max_tr(struct trace_array *tr, struct task_struct *tsk, int cpu,
1531               void *cond_data)
1532 {
1533         if (tr->stop_count)
1534                 return;
1535
1536         WARN_ON_ONCE(!irqs_disabled());
1537
1538         if (!tr->allocated_snapshot) {
1539                 /* Only the nop tracer should hit this when disabling */
1540                 WARN_ON_ONCE(tr->current_trace != &nop_trace);
1541                 return;
1542         }
1543
1544         arch_spin_lock(&tr->max_lock);
1545
1546         /* Inherit the recordable setting from trace_buffer */
1547         if (ring_buffer_record_is_set_on(tr->trace_buffer.buffer))
1548                 ring_buffer_record_on(tr->max_buffer.buffer);
1549         else
1550                 ring_buffer_record_off(tr->max_buffer.buffer);
1551
1552 #ifdef CONFIG_TRACER_SNAPSHOT
1553         if (tr->cond_snapshot && !tr->cond_snapshot->update(tr, cond_data))
1554                 goto out_unlock;
1555 #endif
1556         swap(tr->trace_buffer.buffer, tr->max_buffer.buffer);
1557
1558         __update_max_tr(tr, tsk, cpu);
1559
1560  out_unlock:
1561         arch_spin_unlock(&tr->max_lock);
1562 }
1563
1564 /**
1565  * update_max_tr_single - only copy one trace over, and reset the rest
1566  * @tr - tracer
1567  * @tsk - task with the latency
1568  * @cpu - the cpu of the buffer to copy.
1569  *
1570  * Flip the trace of a single CPU buffer between the @tr and the max_tr.
1571  */
1572 void
1573 update_max_tr_single(struct trace_array *tr, struct task_struct *tsk, int cpu)
1574 {
1575         int ret;
1576
1577         if (tr->stop_count)
1578                 return;
1579
1580         WARN_ON_ONCE(!irqs_disabled());
1581         if (!tr->allocated_snapshot) {
1582                 /* Only the nop tracer should hit this when disabling */
1583                 WARN_ON_ONCE(tr->current_trace != &nop_trace);
1584                 return;
1585         }
1586
1587         arch_spin_lock(&tr->max_lock);
1588
1589         ret = ring_buffer_swap_cpu(tr->max_buffer.buffer, tr->trace_buffer.buffer, cpu);
1590
1591         if (ret == -EBUSY) {
1592                 /*
1593                  * We failed to swap the buffer due to a commit taking
1594                  * place on this CPU. We fail to record, but we reset
1595                  * the max trace buffer (no one writes directly to it)
1596                  * and flag that it failed.
1597                  */
1598                 trace_array_printk_buf(tr->max_buffer.buffer, _THIS_IP_,
1599                         "Failed to swap buffers due to commit in progress\n");
1600         }
1601
1602         WARN_ON_ONCE(ret && ret != -EAGAIN && ret != -EBUSY);
1603
1604         __update_max_tr(tr, tsk, cpu);
1605         arch_spin_unlock(&tr->max_lock);
1606 }
1607 #endif /* CONFIG_TRACER_MAX_TRACE */
1608
1609 static int wait_on_pipe(struct trace_iterator *iter, int full)
1610 {
1611         /* Iterators are static, they should be filled or empty */
1612         if (trace_buffer_iter(iter, iter->cpu_file))
1613                 return 0;
1614
1615         return ring_buffer_wait(iter->trace_buffer->buffer, iter->cpu_file,
1616                                 full);
1617 }
1618
1619 #ifdef CONFIG_FTRACE_STARTUP_TEST
1620 static bool selftests_can_run;
1621
1622 struct trace_selftests {
1623         struct list_head                list;
1624         struct tracer                   *type;
1625 };
1626
1627 static LIST_HEAD(postponed_selftests);
1628
1629 static int save_selftest(struct tracer *type)
1630 {
1631         struct trace_selftests *selftest;
1632
1633         selftest = kmalloc(sizeof(*selftest), GFP_KERNEL);
1634         if (!selftest)
1635                 return -ENOMEM;
1636
1637         selftest->type = type;
1638         list_add(&selftest->list, &postponed_selftests);
1639         return 0;
1640 }
1641
1642 static int run_tracer_selftest(struct tracer *type)
1643 {
1644         struct trace_array *tr = &global_trace;
1645         struct tracer *saved_tracer = tr->current_trace;
1646         int ret;
1647
1648         if (!type->selftest || tracing_selftest_disabled)
1649                 return 0;
1650
1651         /*
1652          * If a tracer registers early in boot up (before scheduling is
1653          * initialized and such), then do not run its selftests yet.
1654          * Instead, run it a little later in the boot process.
1655          */
1656         if (!selftests_can_run)
1657                 return save_selftest(type);
1658
1659         /*
1660          * Run a selftest on this tracer.
1661          * Here we reset the trace buffer, and set the current
1662          * tracer to be this tracer. The tracer can then run some
1663          * internal tracing to verify that everything is in order.
1664          * If we fail, we do not register this tracer.
1665          */
1666         tracing_reset_online_cpus(&tr->trace_buffer);
1667
1668         tr->current_trace = type;
1669
1670 #ifdef CONFIG_TRACER_MAX_TRACE
1671         if (type->use_max_tr) {
1672                 /* If we expanded the buffers, make sure the max is expanded too */
1673                 if (ring_buffer_expanded)
1674                         ring_buffer_resize(tr->max_buffer.buffer, trace_buf_size,
1675                                            RING_BUFFER_ALL_CPUS);
1676                 tr->allocated_snapshot = true;
1677         }
1678 #endif
1679
1680         /* the test is responsible for initializing and enabling */
1681         pr_info("Testing tracer %s: ", type->name);
1682         ret = type->selftest(type, tr);
1683         /* the test is responsible for resetting too */
1684         tr->current_trace = saved_tracer;
1685         if (ret) {
1686                 printk(KERN_CONT "FAILED!\n");
1687                 /* Add the warning after printing 'FAILED' */
1688                 WARN_ON(1);
1689                 return -1;
1690         }
1691         /* Only reset on passing, to avoid touching corrupted buffers */
1692         tracing_reset_online_cpus(&tr->trace_buffer);
1693
1694 #ifdef CONFIG_TRACER_MAX_TRACE
1695         if (type->use_max_tr) {
1696                 tr->allocated_snapshot = false;
1697
1698                 /* Shrink the max buffer again */
1699                 if (ring_buffer_expanded)
1700                         ring_buffer_resize(tr->max_buffer.buffer, 1,
1701                                            RING_BUFFER_ALL_CPUS);
1702         }
1703 #endif
1704
1705         printk(KERN_CONT "PASSED\n");
1706         return 0;
1707 }
1708
1709 static __init int init_trace_selftests(void)
1710 {
1711         struct trace_selftests *p, *n;
1712         struct tracer *t, **last;
1713         int ret;
1714
1715         selftests_can_run = true;
1716
1717         mutex_lock(&trace_types_lock);
1718
1719         if (list_empty(&postponed_selftests))
1720                 goto out;
1721
1722         pr_info("Running postponed tracer tests:\n");
1723
1724         list_for_each_entry_safe(p, n, &postponed_selftests, list) {
1725                 ret = run_tracer_selftest(p->type);
1726                 /* If the test fails, then warn and remove from available_tracers */
1727                 if (ret < 0) {
1728                         WARN(1, "tracer: %s failed selftest, disabling\n",
1729                              p->type->name);
1730                         last = &trace_types;
1731                         for (t = trace_types; t; t = t->next) {
1732                                 if (t == p->type) {
1733                                         *last = t->next;
1734                                         break;
1735                                 }
1736                                 last = &t->next;
1737                         }
1738                 }
1739                 list_del(&p->list);
1740                 kfree(p);
1741         }
1742
1743  out:
1744         mutex_unlock(&trace_types_lock);
1745
1746         return 0;
1747 }
1748 core_initcall(init_trace_selftests);
1749 #else
1750 static inline int run_tracer_selftest(struct tracer *type)
1751 {
1752         return 0;
1753 }
1754 #endif /* CONFIG_FTRACE_STARTUP_TEST */
1755
1756 static void add_tracer_options(struct trace_array *tr, struct tracer *t);
1757
1758 static void __init apply_trace_boot_options(void);
1759
1760 /**
1761  * register_tracer - register a tracer with the ftrace system.
1762  * @type - the plugin for the tracer
1763  *
1764  * Register a new plugin tracer.
1765  */
1766 int __init register_tracer(struct tracer *type)
1767 {
1768         struct tracer *t;
1769         int ret = 0;
1770
1771         if (!type->name) {
1772                 pr_info("Tracer must have a name\n");
1773                 return -1;
1774         }
1775
1776         if (strlen(type->name) >= MAX_TRACER_SIZE) {
1777                 pr_info("Tracer has a name longer than %d\n", MAX_TRACER_SIZE);
1778                 return -1;
1779         }
1780
1781         mutex_lock(&trace_types_lock);
1782
1783         tracing_selftest_running = true;
1784
1785         for (t = trace_types; t; t = t->next) {
1786                 if (strcmp(type->name, t->name) == 0) {
1787                         /* already found */
1788                         pr_info("Tracer %s already registered\n",
1789                                 type->name);
1790                         ret = -1;
1791                         goto out;
1792                 }
1793         }
1794
1795         if (!type->set_flag)
1796                 type->set_flag = &dummy_set_flag;
1797         if (!type->flags) {
1798                 /*allocate a dummy tracer_flags*/
1799                 type->flags = kmalloc(sizeof(*type->flags), GFP_KERNEL);
1800                 if (!type->flags) {
1801                         ret = -ENOMEM;
1802                         goto out;
1803                 }
1804                 type->flags->val = 0;
1805                 type->flags->opts = dummy_tracer_opt;
1806         } else
1807                 if (!type->flags->opts)
1808                         type->flags->opts = dummy_tracer_opt;
1809
1810         /* store the tracer for __set_tracer_option */
1811         type->flags->trace = type;
1812
1813         ret = run_tracer_selftest(type);
1814         if (ret < 0)
1815                 goto out;
1816
1817         type->next = trace_types;
1818         trace_types = type;
1819         add_tracer_options(&global_trace, type);
1820
1821  out:
1822         tracing_selftest_running = false;
1823         mutex_unlock(&trace_types_lock);
1824
1825         if (ret || !default_bootup_tracer)
1826                 goto out_unlock;
1827
1828         if (strncmp(default_bootup_tracer, type->name, MAX_TRACER_SIZE))
1829                 goto out_unlock;
1830
1831         printk(KERN_INFO "Starting tracer '%s'\n", type->name);
1832         /* Do we want this tracer to start on bootup? */
1833         tracing_set_tracer(&global_trace, type->name);
1834         default_bootup_tracer = NULL;
1835
1836         apply_trace_boot_options();
1837
1838         /* disable other selftests, since this will break it. */
1839         tracing_selftest_disabled = true;
1840 #ifdef CONFIG_FTRACE_STARTUP_TEST
1841         printk(KERN_INFO "Disabling FTRACE selftests due to running tracer '%s'\n",
1842                type->name);
1843 #endif
1844
1845  out_unlock:
1846         return ret;
1847 }
1848
1849 void tracing_reset(struct trace_buffer *buf, int cpu)
1850 {
1851         struct ring_buffer *buffer = buf->buffer;
1852
1853         if (!buffer)
1854                 return;
1855
1856         ring_buffer_record_disable(buffer);
1857
1858         /* Make sure all commits have finished */
1859         synchronize_rcu();
1860         ring_buffer_reset_cpu(buffer, cpu);
1861
1862         ring_buffer_record_enable(buffer);
1863 }
1864
1865 void tracing_reset_online_cpus(struct trace_buffer *buf)
1866 {
1867         struct ring_buffer *buffer = buf->buffer;
1868         int cpu;
1869
1870         if (!buffer)
1871                 return;
1872
1873         ring_buffer_record_disable(buffer);
1874
1875         /* Make sure all commits have finished */
1876         synchronize_rcu();
1877
1878         buf->time_start = buffer_ftrace_now(buf, buf->cpu);
1879
1880         for_each_online_cpu(cpu)
1881                 ring_buffer_reset_cpu(buffer, cpu);
1882
1883         ring_buffer_record_enable(buffer);
1884 }
1885
1886 /* Must have trace_types_lock held */
1887 void tracing_reset_all_online_cpus(void)
1888 {
1889         struct trace_array *tr;
1890
1891         list_for_each_entry(tr, &ftrace_trace_arrays, list) {
1892                 if (!tr->clear_trace)
1893                         continue;
1894                 tr->clear_trace = false;
1895                 tracing_reset_online_cpus(&tr->trace_buffer);
1896 #ifdef CONFIG_TRACER_MAX_TRACE
1897                 tracing_reset_online_cpus(&tr->max_buffer);
1898 #endif
1899         }
1900 }
1901
1902 static int *tgid_map;
1903
1904 #define SAVED_CMDLINES_DEFAULT 128
1905 #define NO_CMDLINE_MAP UINT_MAX
1906 static arch_spinlock_t trace_cmdline_lock = __ARCH_SPIN_LOCK_UNLOCKED;
1907 struct saved_cmdlines_buffer {
1908         unsigned map_pid_to_cmdline[PID_MAX_DEFAULT+1];
1909         unsigned *map_cmdline_to_pid;
1910         unsigned cmdline_num;
1911         int cmdline_idx;
1912         char *saved_cmdlines;
1913 };
1914 static struct saved_cmdlines_buffer *savedcmd;
1915
1916 /* temporary disable recording */
1917 static atomic_t trace_record_taskinfo_disabled __read_mostly;
1918
1919 static inline char *get_saved_cmdlines(int idx)
1920 {
1921         return &savedcmd->saved_cmdlines[idx * TASK_COMM_LEN];
1922 }
1923
1924 static inline void set_cmdline(int idx, const char *cmdline)
1925 {
1926         strncpy(get_saved_cmdlines(idx), cmdline, TASK_COMM_LEN);
1927 }
1928
1929 static int allocate_cmdlines_buffer(unsigned int val,
1930                                     struct saved_cmdlines_buffer *s)
1931 {
1932         s->map_cmdline_to_pid = kmalloc_array(val,
1933                                               sizeof(*s->map_cmdline_to_pid),
1934                                               GFP_KERNEL);
1935         if (!s->map_cmdline_to_pid)
1936                 return -ENOMEM;
1937
1938         s->saved_cmdlines = kmalloc_array(TASK_COMM_LEN, val, GFP_KERNEL);
1939         if (!s->saved_cmdlines) {
1940                 kfree(s->map_cmdline_to_pid);
1941                 return -ENOMEM;
1942         }
1943
1944         s->cmdline_idx = 0;
1945         s->cmdline_num = val;
1946         memset(&s->map_pid_to_cmdline, NO_CMDLINE_MAP,
1947                sizeof(s->map_pid_to_cmdline));
1948         memset(s->map_cmdline_to_pid, NO_CMDLINE_MAP,
1949                val * sizeof(*s->map_cmdline_to_pid));
1950
1951         return 0;
1952 }
1953
1954 static int trace_create_savedcmd(void)
1955 {
1956         int ret;
1957
1958         savedcmd = kmalloc(sizeof(*savedcmd), GFP_KERNEL);
1959         if (!savedcmd)
1960                 return -ENOMEM;
1961
1962         ret = allocate_cmdlines_buffer(SAVED_CMDLINES_DEFAULT, savedcmd);
1963         if (ret < 0) {
1964                 kfree(savedcmd);
1965                 savedcmd = NULL;
1966                 return -ENOMEM;
1967         }
1968
1969         return 0;
1970 }
1971
1972 int is_tracing_stopped(void)
1973 {
1974         return global_trace.stop_count;
1975 }
1976
1977 /**
1978  * tracing_start - quick start of the tracer
1979  *
1980  * If tracing is enabled but was stopped by tracing_stop,
1981  * this will start the tracer back up.
1982  */
1983 void tracing_start(void)
1984 {
1985         struct ring_buffer *buffer;
1986         unsigned long flags;
1987
1988         if (tracing_disabled)
1989                 return;
1990
1991         raw_spin_lock_irqsave(&global_trace.start_lock, flags);
1992         if (--global_trace.stop_count) {
1993                 if (global_trace.stop_count < 0) {
1994                         /* Someone screwed up their debugging */
1995                         WARN_ON_ONCE(1);
1996                         global_trace.stop_count = 0;
1997                 }
1998                 goto out;
1999         }
2000
2001         /* Prevent the buffers from switching */
2002         arch_spin_lock(&global_trace.max_lock);
2003
2004         buffer = global_trace.trace_buffer.buffer;
2005         if (buffer)
2006                 ring_buffer_record_enable(buffer);
2007
2008 #ifdef CONFIG_TRACER_MAX_TRACE
2009         buffer = global_trace.max_buffer.buffer;
2010         if (buffer)
2011                 ring_buffer_record_enable(buffer);
2012 #endif
2013
2014         arch_spin_unlock(&global_trace.max_lock);
2015
2016  out:
2017         raw_spin_unlock_irqrestore(&global_trace.start_lock, flags);
2018 }
2019
2020 static void tracing_start_tr(struct trace_array *tr)
2021 {
2022         struct ring_buffer *buffer;
2023         unsigned long flags;
2024
2025         if (tracing_disabled)
2026                 return;
2027
2028         /* If global, we need to also start the max tracer */
2029         if (tr->flags & TRACE_ARRAY_FL_GLOBAL)
2030                 return tracing_start();
2031
2032         raw_spin_lock_irqsave(&tr->start_lock, flags);
2033
2034         if (--tr->stop_count) {
2035                 if (tr->stop_count < 0) {
2036                         /* Someone screwed up their debugging */
2037                         WARN_ON_ONCE(1);
2038                         tr->stop_count = 0;
2039                 }
2040                 goto out;
2041         }
2042
2043         buffer = tr->trace_buffer.buffer;
2044         if (buffer)
2045                 ring_buffer_record_enable(buffer);
2046
2047  out:
2048         raw_spin_unlock_irqrestore(&tr->start_lock, flags);
2049 }
2050
2051 /**
2052  * tracing_stop - quick stop of the tracer
2053  *
2054  * Light weight way to stop tracing. Use in conjunction with
2055  * tracing_start.
2056  */
2057 void tracing_stop(void)
2058 {
2059         struct ring_buffer *buffer;
2060         unsigned long flags;
2061
2062         raw_spin_lock_irqsave(&global_trace.start_lock, flags);
2063         if (global_trace.stop_count++)
2064                 goto out;
2065
2066         /* Prevent the buffers from switching */
2067         arch_spin_lock(&global_trace.max_lock);
2068
2069         buffer = global_trace.trace_buffer.buffer;
2070         if (buffer)
2071                 ring_buffer_record_disable(buffer);
2072
2073 #ifdef CONFIG_TRACER_MAX_TRACE
2074         buffer = global_trace.max_buffer.buffer;
2075         if (buffer)
2076                 ring_buffer_record_disable(buffer);
2077 #endif
2078
2079         arch_spin_unlock(&global_trace.max_lock);
2080
2081  out:
2082         raw_spin_unlock_irqrestore(&global_trace.start_lock, flags);
2083 }
2084
2085 static void tracing_stop_tr(struct trace_array *tr)
2086 {
2087         struct ring_buffer *buffer;
2088         unsigned long flags;
2089
2090         /* If global, we need to also stop the max tracer */
2091         if (tr->flags & TRACE_ARRAY_FL_GLOBAL)
2092                 return tracing_stop();
2093
2094         raw_spin_lock_irqsave(&tr->start_lock, flags);
2095         if (tr->stop_count++)
2096                 goto out;
2097
2098         buffer = tr->trace_buffer.buffer;
2099         if (buffer)
2100                 ring_buffer_record_disable(buffer);
2101
2102  out:
2103         raw_spin_unlock_irqrestore(&tr->start_lock, flags);
2104 }
2105
2106 static int trace_save_cmdline(struct task_struct *tsk)
2107 {
2108         unsigned pid, idx;
2109
2110         /* treat recording of idle task as a success */
2111         if (!tsk->pid)
2112                 return 1;
2113
2114         if (unlikely(tsk->pid > PID_MAX_DEFAULT))
2115                 return 0;
2116
2117         /*
2118          * It's not the end of the world if we don't get
2119          * the lock, but we also don't want to spin
2120          * nor do we want to disable interrupts,
2121          * so if we miss here, then better luck next time.
2122          */
2123         if (!arch_spin_trylock(&trace_cmdline_lock))
2124                 return 0;
2125
2126         idx = savedcmd->map_pid_to_cmdline[tsk->pid];
2127         if (idx == NO_CMDLINE_MAP) {
2128                 idx = (savedcmd->cmdline_idx + 1) % savedcmd->cmdline_num;
2129
2130                 /*
2131                  * Check whether the cmdline buffer at idx has a pid
2132                  * mapped. We are going to overwrite that entry so we
2133                  * need to clear the map_pid_to_cmdline. Otherwise we
2134                  * would read the new comm for the old pid.
2135                  */
2136                 pid = savedcmd->map_cmdline_to_pid[idx];
2137                 if (pid != NO_CMDLINE_MAP)
2138                         savedcmd->map_pid_to_cmdline[pid] = NO_CMDLINE_MAP;
2139
2140                 savedcmd->map_cmdline_to_pid[idx] = tsk->pid;
2141                 savedcmd->map_pid_to_cmdline[tsk->pid] = idx;
2142
2143                 savedcmd->cmdline_idx = idx;
2144         }
2145
2146         set_cmdline(idx, tsk->comm);
2147
2148         arch_spin_unlock(&trace_cmdline_lock);
2149
2150         return 1;
2151 }
2152
2153 static void __trace_find_cmdline(int pid, char comm[])
2154 {
2155         unsigned map;
2156
2157         if (!pid) {
2158                 strcpy(comm, "<idle>");
2159                 return;
2160         }
2161
2162         if (WARN_ON_ONCE(pid < 0)) {
2163                 strcpy(comm, "<XXX>");
2164                 return;
2165         }
2166
2167         if (pid > PID_MAX_DEFAULT) {
2168                 strcpy(comm, "<...>");
2169                 return;
2170         }
2171
2172         map = savedcmd->map_pid_to_cmdline[pid];
2173         if (map != NO_CMDLINE_MAP)
2174                 strlcpy(comm, get_saved_cmdlines(map), TASK_COMM_LEN);
2175         else
2176                 strcpy(comm, "<...>");
2177 }
2178
2179 void trace_find_cmdline(int pid, char comm[])
2180 {
2181         preempt_disable();
2182         arch_spin_lock(&trace_cmdline_lock);
2183
2184         __trace_find_cmdline(pid, comm);
2185
2186         arch_spin_unlock(&trace_cmdline_lock);
2187         preempt_enable();
2188 }
2189
2190 int trace_find_tgid(int pid)
2191 {
2192         if (unlikely(!tgid_map || !pid || pid > PID_MAX_DEFAULT))
2193                 return 0;
2194
2195         return tgid_map[pid];
2196 }
2197
2198 static int trace_save_tgid(struct task_struct *tsk)
2199 {
2200         /* treat recording of idle task as a success */
2201         if (!tsk->pid)
2202                 return 1;
2203
2204         if (unlikely(!tgid_map || tsk->pid > PID_MAX_DEFAULT))
2205                 return 0;
2206
2207         tgid_map[tsk->pid] = tsk->tgid;
2208         return 1;
2209 }
2210
2211 static bool tracing_record_taskinfo_skip(int flags)
2212 {
2213         if (unlikely(!(flags & (TRACE_RECORD_CMDLINE | TRACE_RECORD_TGID))))
2214                 return true;
2215         if (atomic_read(&trace_record_taskinfo_disabled) || !tracing_is_on())
2216                 return true;
2217         if (!__this_cpu_read(trace_taskinfo_save))
2218                 return true;
2219         return false;
2220 }
2221
2222 /**
2223  * tracing_record_taskinfo - record the task info of a task
2224  *
2225  * @task  - task to record
2226  * @flags - TRACE_RECORD_CMDLINE for recording comm
2227  *        - TRACE_RECORD_TGID for recording tgid
2228  */
2229 void tracing_record_taskinfo(struct task_struct *task, int flags)
2230 {
2231         bool done;
2232
2233         if (tracing_record_taskinfo_skip(flags))
2234                 return;
2235
2236         /*
2237          * Record as much task information as possible. If some fail, continue
2238          * to try to record the others.
2239          */
2240         done = !(flags & TRACE_RECORD_CMDLINE) || trace_save_cmdline(task);
2241         done &= !(flags & TRACE_RECORD_TGID) || trace_save_tgid(task);
2242
2243         /* If recording any information failed, retry again soon. */
2244         if (!done)
2245                 return;
2246
2247         __this_cpu_write(trace_taskinfo_save, false);
2248 }
2249
2250 /**
2251  * tracing_record_taskinfo_sched_switch - record task info for sched_switch
2252  *
2253  * @prev - previous task during sched_switch
2254  * @next - next task during sched_switch
2255  * @flags - TRACE_RECORD_CMDLINE for recording comm
2256  *          TRACE_RECORD_TGID for recording tgid
2257  */
2258 void tracing_record_taskinfo_sched_switch(struct task_struct *prev,
2259                                           struct task_struct *next, int flags)
2260 {
2261         bool done;
2262
2263         if (tracing_record_taskinfo_skip(flags))
2264                 return;
2265
2266         /*
2267          * Record as much task information as possible. If some fail, continue
2268          * to try to record the others.
2269          */
2270         done  = !(flags & TRACE_RECORD_CMDLINE) || trace_save_cmdline(prev);
2271         done &= !(flags & TRACE_RECORD_CMDLINE) || trace_save_cmdline(next);
2272         done &= !(flags & TRACE_RECORD_TGID) || trace_save_tgid(prev);
2273         done &= !(flags & TRACE_RECORD_TGID) || trace_save_tgid(next);
2274
2275         /* If recording any information failed, retry again soon. */
2276         if (!done)
2277                 return;
2278
2279         __this_cpu_write(trace_taskinfo_save, false);
2280 }
2281
2282 /* Helpers to record a specific task information */
2283 void tracing_record_cmdline(struct task_struct *task)
2284 {
2285         tracing_record_taskinfo(task, TRACE_RECORD_CMDLINE);
2286 }
2287
2288 void tracing_record_tgid(struct task_struct *task)
2289 {
2290         tracing_record_taskinfo(task, TRACE_RECORD_TGID);
2291 }
2292
2293 /*
2294  * Several functions return TRACE_TYPE_PARTIAL_LINE if the trace_seq
2295  * overflowed, and TRACE_TYPE_HANDLED otherwise. This helper function
2296  * simplifies those functions and keeps them in sync.
2297  */
2298 enum print_line_t trace_handle_return(struct trace_seq *s)
2299 {
2300         return trace_seq_has_overflowed(s) ?
2301                 TRACE_TYPE_PARTIAL_LINE : TRACE_TYPE_HANDLED;
2302 }
2303 EXPORT_SYMBOL_GPL(trace_handle_return);
2304
2305 void
2306 tracing_generic_entry_update(struct trace_entry *entry, unsigned long flags,
2307                              int pc)
2308 {
2309         struct task_struct *tsk = current;
2310
2311         entry->preempt_count            = pc & 0xff;
2312         entry->pid                      = (tsk) ? tsk->pid : 0;
2313         entry->flags =
2314 #ifdef CONFIG_TRACE_IRQFLAGS_SUPPORT
2315                 (irqs_disabled_flags(flags) ? TRACE_FLAG_IRQS_OFF : 0) |
2316 #else
2317                 TRACE_FLAG_IRQS_NOSUPPORT |
2318 #endif
2319                 ((pc & NMI_MASK    ) ? TRACE_FLAG_NMI     : 0) |
2320                 ((pc & HARDIRQ_MASK) ? TRACE_FLAG_HARDIRQ : 0) |
2321                 ((pc & SOFTIRQ_OFFSET) ? TRACE_FLAG_SOFTIRQ : 0) |
2322                 (tif_need_resched() ? TRACE_FLAG_NEED_RESCHED : 0) |
2323                 (test_preempt_need_resched() ? TRACE_FLAG_PREEMPT_RESCHED : 0);
2324 }
2325 EXPORT_SYMBOL_GPL(tracing_generic_entry_update);
2326
2327 struct ring_buffer_event *
2328 trace_buffer_lock_reserve(struct ring_buffer *buffer,
2329                           int type,
2330                           unsigned long len,
2331                           unsigned long flags, int pc)
2332 {
2333         return __trace_buffer_lock_reserve(buffer, type, len, flags, pc);
2334 }
2335
2336 DEFINE_PER_CPU(struct ring_buffer_event *, trace_buffered_event);
2337 DEFINE_PER_CPU(int, trace_buffered_event_cnt);
2338 static int trace_buffered_event_ref;
2339
2340 /**
2341  * trace_buffered_event_enable - enable buffering events
2342  *
2343  * When events are being filtered, it is quicker to use a temporary
2344  * buffer to write the event data into if there's a likely chance
2345  * that it will not be committed. The discard of the ring buffer
2346  * is not as fast as committing, and is much slower than copying
2347  * a commit.
2348  *
2349  * When an event is to be filtered, allocate per cpu buffers to
2350  * write the event data into, and if the event is filtered and discarded
2351  * it is simply dropped, otherwise, the entire data is to be committed
2352  * in one shot.
2353  */
2354 void trace_buffered_event_enable(void)
2355 {
2356         struct ring_buffer_event *event;
2357         struct page *page;
2358         int cpu;
2359
2360         WARN_ON_ONCE(!mutex_is_locked(&event_mutex));
2361
2362         if (trace_buffered_event_ref++)
2363                 return;
2364
2365         for_each_tracing_cpu(cpu) {
2366                 page = alloc_pages_node(cpu_to_node(cpu),
2367                                         GFP_KERNEL | __GFP_NORETRY, 0);
2368                 if (!page)
2369                         goto failed;
2370
2371                 event = page_address(page);
2372                 memset(event, 0, sizeof(*event));
2373
2374                 per_cpu(trace_buffered_event, cpu) = event;
2375
2376                 preempt_disable();
2377                 if (cpu == smp_processor_id() &&
2378                     this_cpu_read(trace_buffered_event) !=
2379                     per_cpu(trace_buffered_event, cpu))
2380                         WARN_ON_ONCE(1);
2381                 preempt_enable();
2382         }
2383
2384         return;
2385  failed:
2386         trace_buffered_event_disable();
2387 }
2388
2389 static void enable_trace_buffered_event(void *data)
2390 {
2391         /* Probably not needed, but do it anyway */
2392         smp_rmb();
2393         this_cpu_dec(trace_buffered_event_cnt);
2394 }
2395
2396 static void disable_trace_buffered_event(void *data)
2397 {
2398         this_cpu_inc(trace_buffered_event_cnt);
2399 }
2400
2401 /**
2402  * trace_buffered_event_disable - disable buffering events
2403  *
2404  * When a filter is removed, it is faster to not use the buffered
2405  * events, and to commit directly into the ring buffer. Free up
2406  * the temp buffers when there are no more users. This requires
2407  * special synchronization with current events.
2408  */
2409 void trace_buffered_event_disable(void)
2410 {
2411         int cpu;
2412
2413         WARN_ON_ONCE(!mutex_is_locked(&event_mutex));
2414
2415         if (WARN_ON_ONCE(!trace_buffered_event_ref))
2416                 return;
2417
2418         if (--trace_buffered_event_ref)
2419                 return;
2420
2421         preempt_disable();
2422         /* For each CPU, set the buffer as used. */
2423         smp_call_function_many(tracing_buffer_mask,
2424                                disable_trace_buffered_event, NULL, 1);
2425         preempt_enable();
2426
2427         /* Wait for all current users to finish */
2428         synchronize_rcu();
2429
2430         for_each_tracing_cpu(cpu) {
2431                 free_page((unsigned long)per_cpu(trace_buffered_event, cpu));
2432                 per_cpu(trace_buffered_event, cpu) = NULL;
2433         }
2434         /*
2435          * Make sure trace_buffered_event is NULL before clearing
2436          * trace_buffered_event_cnt.
2437          */
2438         smp_wmb();
2439
2440         preempt_disable();
2441         /* Do the work on each cpu */
2442         smp_call_function_many(tracing_buffer_mask,
2443                                enable_trace_buffered_event, NULL, 1);
2444         preempt_enable();
2445 }
2446
2447 static struct ring_buffer *temp_buffer;
2448
2449 struct ring_buffer_event *
2450 trace_event_buffer_lock_reserve(struct ring_buffer **current_rb,
2451                           struct trace_event_file *trace_file,
2452                           int type, unsigned long len,
2453                           unsigned long flags, int pc)
2454 {
2455         struct ring_buffer_event *entry;
2456         int val;
2457
2458         *current_rb = trace_file->tr->trace_buffer.buffer;
2459
2460         if (!ring_buffer_time_stamp_abs(*current_rb) && (trace_file->flags &
2461              (EVENT_FILE_FL_SOFT_DISABLED | EVENT_FILE_FL_FILTERED)) &&
2462             (entry = this_cpu_read(trace_buffered_event))) {
2463                 /* Try to use the per cpu buffer first */
2464                 val = this_cpu_inc_return(trace_buffered_event_cnt);
2465                 if (val == 1) {
2466                         trace_event_setup(entry, type, flags, pc);
2467                         entry->array[0] = len;
2468                         return entry;
2469                 }
2470                 this_cpu_dec(trace_buffered_event_cnt);
2471         }
2472
2473         entry = __trace_buffer_lock_reserve(*current_rb,
2474                                             type, len, flags, pc);
2475         /*
2476          * If tracing is off, but we have triggers enabled
2477          * we still need to look at the event data. Use the temp_buffer
2478          * to store the trace event for the tigger to use. It's recusive
2479          * safe and will not be recorded anywhere.
2480          */
2481         if (!entry && trace_file->flags & EVENT_FILE_FL_TRIGGER_COND) {
2482                 *current_rb = temp_buffer;
2483                 entry = __trace_buffer_lock_reserve(*current_rb,
2484                                                     type, len, flags, pc);
2485         }
2486         return entry;
2487 }
2488 EXPORT_SYMBOL_GPL(trace_event_buffer_lock_reserve);
2489
2490 static DEFINE_SPINLOCK(tracepoint_iter_lock);
2491 static DEFINE_MUTEX(tracepoint_printk_mutex);
2492
2493 static void output_printk(struct trace_event_buffer *fbuffer)
2494 {
2495         struct trace_event_call *event_call;
2496         struct trace_event *event;
2497         unsigned long flags;
2498         struct trace_iterator *iter = tracepoint_print_iter;
2499
2500         /* We should never get here if iter is NULL */
2501         if (WARN_ON_ONCE(!iter))
2502                 return;
2503
2504         event_call = fbuffer->trace_file->event_call;
2505         if (!event_call || !event_call->event.funcs ||
2506             !event_call->event.funcs->trace)
2507                 return;
2508
2509         event = &fbuffer->trace_file->event_call->event;
2510
2511         spin_lock_irqsave(&tracepoint_iter_lock, flags);
2512         trace_seq_init(&iter->seq);
2513         iter->ent = fbuffer->entry;
2514         event_call->event.funcs->trace(iter, 0, event);
2515         trace_seq_putc(&iter->seq, 0);
2516         printk("%s", iter->seq.buffer);
2517
2518         spin_unlock_irqrestore(&tracepoint_iter_lock, flags);
2519 }
2520
2521 int tracepoint_printk_sysctl(struct ctl_table *table, int write,
2522                              void __user *buffer, size_t *lenp,
2523                              loff_t *ppos)
2524 {
2525         int save_tracepoint_printk;
2526         int ret;
2527
2528         mutex_lock(&tracepoint_printk_mutex);
2529         save_tracepoint_printk = tracepoint_printk;
2530
2531         ret = proc_dointvec(table, write, buffer, lenp, ppos);
2532
2533         /*
2534          * This will force exiting early, as tracepoint_printk
2535          * is always zero when tracepoint_printk_iter is not allocated
2536          */
2537         if (!tracepoint_print_iter)
2538                 tracepoint_printk = 0;
2539
2540         if (save_tracepoint_printk == tracepoint_printk)
2541                 goto out;
2542
2543         if (tracepoint_printk)
2544                 static_key_enable(&tracepoint_printk_key.key);
2545         else
2546                 static_key_disable(&tracepoint_printk_key.key);
2547
2548  out:
2549         mutex_unlock(&tracepoint_printk_mutex);
2550
2551         return ret;
2552 }
2553
2554 void trace_event_buffer_commit(struct trace_event_buffer *fbuffer)
2555 {
2556         if (static_key_false(&tracepoint_printk_key.key))
2557                 output_printk(fbuffer);
2558
2559         event_trigger_unlock_commit(fbuffer->trace_file, fbuffer->buffer,
2560                                     fbuffer->event, fbuffer->entry,
2561                                     fbuffer->flags, fbuffer->pc);
2562 }
2563 EXPORT_SYMBOL_GPL(trace_event_buffer_commit);
2564
2565 /*
2566  * Skip 3:
2567  *
2568  *   trace_buffer_unlock_commit_regs()
2569  *   trace_event_buffer_commit()
2570  *   trace_event_raw_event_xxx()
2571  */
2572 # define STACK_SKIP 3
2573
2574 void trace_buffer_unlock_commit_regs(struct trace_array *tr,
2575                                      struct ring_buffer *buffer,
2576                                      struct ring_buffer_event *event,
2577                                      unsigned long flags, int pc,
2578                                      struct pt_regs *regs)
2579 {
2580         __buffer_unlock_commit(buffer, event);
2581
2582         /*
2583          * If regs is not set, then skip the necessary functions.
2584          * Note, we can still get here via blktrace, wakeup tracer
2585          * and mmiotrace, but that's ok if they lose a function or
2586          * two. They are not that meaningful.
2587          */
2588         ftrace_trace_stack(tr, buffer, flags, regs ? 0 : STACK_SKIP, pc, regs);
2589         ftrace_trace_userstack(buffer, flags, pc);
2590 }
2591
2592 /*
2593  * Similar to trace_buffer_unlock_commit_regs() but do not dump stack.
2594  */
2595 void
2596 trace_buffer_unlock_commit_nostack(struct ring_buffer *buffer,
2597                                    struct ring_buffer_event *event)
2598 {
2599         __buffer_unlock_commit(buffer, event);
2600 }
2601
2602 static void
2603 trace_process_export(struct trace_export *export,
2604                struct ring_buffer_event *event)
2605 {
2606         struct trace_entry *entry;
2607         unsigned int size = 0;
2608
2609         entry = ring_buffer_event_data(event);
2610         size = ring_buffer_event_length(event);
2611         export->write(export, entry, size);
2612 }
2613
2614 static DEFINE_MUTEX(ftrace_export_lock);
2615
2616 static struct trace_export __rcu *ftrace_exports_list __read_mostly;
2617
2618 static DEFINE_STATIC_KEY_FALSE(ftrace_exports_enabled);
2619
2620 static inline void ftrace_exports_enable(void)
2621 {
2622         static_branch_enable(&ftrace_exports_enabled);
2623 }
2624
2625 static inline void ftrace_exports_disable(void)
2626 {
2627         static_branch_disable(&ftrace_exports_enabled);
2628 }
2629
2630 static void ftrace_exports(struct ring_buffer_event *event)
2631 {
2632         struct trace_export *export;
2633
2634         preempt_disable_notrace();
2635
2636         export = rcu_dereference_raw_notrace(ftrace_exports_list);
2637         while (export) {
2638                 trace_process_export(export, event);
2639                 export = rcu_dereference_raw_notrace(export->next);
2640         }
2641
2642         preempt_enable_notrace();
2643 }
2644
2645 static inline void
2646 add_trace_export(struct trace_export **list, struct trace_export *export)
2647 {
2648         rcu_assign_pointer(export->next, *list);
2649         /*
2650          * We are entering export into the list but another
2651          * CPU might be walking that list. We need to make sure
2652          * the export->next pointer is valid before another CPU sees
2653          * the export pointer included into the list.
2654          */
2655         rcu_assign_pointer(*list, export);
2656 }
2657
2658 static inline int
2659 rm_trace_export(struct trace_export **list, struct trace_export *export)
2660 {
2661         struct trace_export **p;
2662
2663         for (p = list; *p != NULL; p = &(*p)->next)
2664                 if (*p == export)
2665                         break;
2666
2667         if (*p != export)
2668                 return -1;
2669
2670         rcu_assign_pointer(*p, (*p)->next);
2671
2672         return 0;
2673 }
2674
2675 static inline void
2676 add_ftrace_export(struct trace_export **list, struct trace_export *export)
2677 {
2678         if (*list == NULL)
2679                 ftrace_exports_enable();
2680
2681         add_trace_export(list, export);
2682 }
2683
2684 static inline int
2685 rm_ftrace_export(struct trace_export **list, struct trace_export *export)
2686 {
2687         int ret;
2688
2689         ret = rm_trace_export(list, export);
2690         if (*list == NULL)
2691                 ftrace_exports_disable();
2692
2693         return ret;
2694 }
2695
2696 int register_ftrace_export(struct trace_export *export)
2697 {
2698         if (WARN_ON_ONCE(!export->write))
2699                 return -1;
2700
2701         mutex_lock(&ftrace_export_lock);
2702
2703         add_ftrace_export(&ftrace_exports_list, export);
2704
2705         mutex_unlock(&ftrace_export_lock);
2706
2707         return 0;
2708 }
2709 EXPORT_SYMBOL_GPL(register_ftrace_export);
2710
2711 int unregister_ftrace_export(struct trace_export *export)
2712 {
2713         int ret;
2714
2715         mutex_lock(&ftrace_export_lock);
2716
2717         ret = rm_ftrace_export(&ftrace_exports_list, export);
2718
2719         mutex_unlock(&ftrace_export_lock);
2720
2721         return ret;
2722 }
2723 EXPORT_SYMBOL_GPL(unregister_ftrace_export);
2724
2725 void
2726 trace_function(struct trace_array *tr,
2727                unsigned long ip, unsigned long parent_ip, unsigned long flags,
2728                int pc)
2729 {
2730         struct trace_event_call *call = &event_function;
2731         struct ring_buffer *buffer = tr->trace_buffer.buffer;
2732         struct ring_buffer_event *event;
2733         struct ftrace_entry *entry;
2734
2735         event = __trace_buffer_lock_reserve(buffer, TRACE_FN, sizeof(*entry),
2736                                             flags, pc);
2737         if (!event)
2738                 return;
2739         entry   = ring_buffer_event_data(event);
2740         entry->ip                       = ip;
2741         entry->parent_ip                = parent_ip;
2742
2743         if (!call_filter_check_discard(call, entry, buffer, event)) {
2744                 if (static_branch_unlikely(&ftrace_exports_enabled))
2745                         ftrace_exports(event);
2746                 __buffer_unlock_commit(buffer, event);
2747         }
2748 }
2749
2750 #ifdef CONFIG_STACKTRACE
2751
2752 #define FTRACE_STACK_MAX_ENTRIES (PAGE_SIZE / sizeof(unsigned long))
2753 struct ftrace_stack {
2754         unsigned long           calls[FTRACE_STACK_MAX_ENTRIES];
2755 };
2756
2757 static DEFINE_PER_CPU(struct ftrace_stack, ftrace_stack);
2758 static DEFINE_PER_CPU(int, ftrace_stack_reserve);
2759
2760 static void __ftrace_trace_stack(struct ring_buffer *buffer,
2761                                  unsigned long flags,
2762                                  int skip, int pc, struct pt_regs *regs)
2763 {
2764         struct trace_event_call *call = &event_kernel_stack;
2765         struct ring_buffer_event *event;
2766         struct stack_entry *entry;
2767         struct stack_trace trace;
2768         int use_stack;
2769         int size = FTRACE_STACK_ENTRIES;
2770
2771         trace.nr_entries        = 0;
2772         trace.skip              = skip;
2773
2774         /*
2775          * Add one, for this function and the call to save_stack_trace()
2776          * If regs is set, then these functions will not be in the way.
2777          */
2778 #ifndef CONFIG_UNWINDER_ORC
2779         if (!regs)
2780                 trace.skip++;
2781 #endif
2782
2783         /*
2784          * Since events can happen in NMIs there's no safe way to
2785          * use the per cpu ftrace_stacks. We reserve it and if an interrupt
2786          * or NMI comes in, it will just have to use the default
2787          * FTRACE_STACK_SIZE.
2788          */
2789         preempt_disable_notrace();
2790
2791         use_stack = __this_cpu_inc_return(ftrace_stack_reserve);
2792         /*
2793          * We don't need any atomic variables, just a barrier.
2794          * If an interrupt comes in, we don't care, because it would
2795          * have exited and put the counter back to what we want.
2796          * We just need a barrier to keep gcc from moving things
2797          * around.
2798          */
2799         barrier();
2800         if (use_stack == 1) {
2801                 trace.entries           = this_cpu_ptr(ftrace_stack.calls);
2802                 trace.max_entries       = FTRACE_STACK_MAX_ENTRIES;
2803
2804                 if (regs)
2805                         save_stack_trace_regs(regs, &trace);
2806                 else
2807                         save_stack_trace(&trace);
2808
2809                 if (trace.nr_entries > size)
2810                         size = trace.nr_entries;
2811         } else
2812                 /* From now on, use_stack is a boolean */
2813                 use_stack = 0;
2814
2815         size *= sizeof(unsigned long);
2816
2817         event = __trace_buffer_lock_reserve(buffer, TRACE_STACK,
2818                                             sizeof(*entry) + size, flags, pc);
2819         if (!event)
2820                 goto out;
2821         entry = ring_buffer_event_data(event);
2822
2823         memset(&entry->caller, 0, size);
2824
2825         if (use_stack)
2826                 memcpy(&entry->caller, trace.entries,
2827                        trace.nr_entries * sizeof(unsigned long));
2828         else {
2829                 trace.max_entries       = FTRACE_STACK_ENTRIES;
2830                 trace.entries           = entry->caller;
2831                 if (regs)
2832                         save_stack_trace_regs(regs, &trace);
2833                 else
2834                         save_stack_trace(&trace);
2835         }
2836
2837         entry->size = trace.nr_entries;
2838
2839         if (!call_filter_check_discard(call, entry, buffer, event))
2840                 __buffer_unlock_commit(buffer, event);
2841
2842  out:
2843         /* Again, don't let gcc optimize things here */
2844         barrier();
2845         __this_cpu_dec(ftrace_stack_reserve);
2846         preempt_enable_notrace();
2847
2848 }
2849
2850 static inline void ftrace_trace_stack(struct trace_array *tr,
2851                                       struct ring_buffer *buffer,
2852                                       unsigned long flags,
2853                                       int skip, int pc, struct pt_regs *regs)
2854 {
2855         if (!(tr->trace_flags & TRACE_ITER_STACKTRACE))
2856                 return;
2857
2858         __ftrace_trace_stack(buffer, flags, skip, pc, regs);
2859 }
2860
2861 void __trace_stack(struct trace_array *tr, unsigned long flags, int skip,
2862                    int pc)
2863 {
2864         struct ring_buffer *buffer = tr->trace_buffer.buffer;
2865
2866         if (rcu_is_watching()) {
2867                 __ftrace_trace_stack(buffer, flags, skip, pc, NULL);
2868                 return;
2869         }
2870
2871         /*
2872          * When an NMI triggers, RCU is enabled via rcu_nmi_enter(),
2873          * but if the above rcu_is_watching() failed, then the NMI
2874          * triggered someplace critical, and rcu_irq_enter() should
2875          * not be called from NMI.
2876          */
2877         if (unlikely(in_nmi()))
2878                 return;
2879
2880         rcu_irq_enter_irqson();
2881         __ftrace_trace_stack(buffer, flags, skip, pc, NULL);
2882         rcu_irq_exit_irqson();
2883 }
2884
2885 /**
2886  * trace_dump_stack - record a stack back trace in the trace buffer
2887  * @skip: Number of functions to skip (helper handlers)
2888  */
2889 void trace_dump_stack(int skip)
2890 {
2891         unsigned long flags;
2892
2893         if (tracing_disabled || tracing_selftest_running)
2894                 return;
2895
2896         local_save_flags(flags);
2897
2898 #ifndef CONFIG_UNWINDER_ORC
2899         /* Skip 1 to skip this function. */
2900         skip++;
2901 #endif
2902         __ftrace_trace_stack(global_trace.trace_buffer.buffer,
2903                              flags, skip, preempt_count(), NULL);
2904 }
2905 EXPORT_SYMBOL_GPL(trace_dump_stack);
2906
2907 static DEFINE_PER_CPU(int, user_stack_count);
2908
2909 void
2910 ftrace_trace_userstack(struct ring_buffer *buffer, unsigned long flags, int pc)
2911 {
2912         struct trace_event_call *call = &event_user_stack;
2913         struct ring_buffer_event *event;
2914         struct userstack_entry *entry;
2915         struct stack_trace trace;
2916
2917         if (!(global_trace.trace_flags & TRACE_ITER_USERSTACKTRACE))
2918                 return;
2919
2920         /*
2921          * NMIs can not handle page faults, even with fix ups.
2922          * The save user stack can (and often does) fault.
2923          */
2924         if (unlikely(in_nmi()))
2925                 return;
2926
2927         /*
2928          * prevent recursion, since the user stack tracing may
2929          * trigger other kernel events.
2930          */
2931         preempt_disable();
2932         if (__this_cpu_read(user_stack_count))
2933                 goto out;
2934
2935         __this_cpu_inc(user_stack_count);
2936
2937         event = __trace_buffer_lock_reserve(buffer, TRACE_USER_STACK,
2938                                             sizeof(*entry), flags, pc);
2939         if (!event)
2940                 goto out_drop_count;
2941         entry   = ring_buffer_event_data(event);
2942
2943         entry->tgid             = current->tgid;
2944         memset(&entry->caller, 0, sizeof(entry->caller));
2945
2946         trace.nr_entries        = 0;
2947         trace.max_entries       = FTRACE_STACK_ENTRIES;
2948         trace.skip              = 0;
2949         trace.entries           = entry->caller;
2950
2951         save_stack_trace_user(&trace);
2952         if (!call_filter_check_discard(call, entry, buffer, event))
2953                 __buffer_unlock_commit(buffer, event);
2954
2955  out_drop_count:
2956         __this_cpu_dec(user_stack_count);
2957  out:
2958         preempt_enable();
2959 }
2960
2961 #ifdef UNUSED
2962 static void __trace_userstack(struct trace_array *tr, unsigned long flags)
2963 {
2964         ftrace_trace_userstack(tr, flags, preempt_count());
2965 }
2966 #endif /* UNUSED */
2967
2968 #endif /* CONFIG_STACKTRACE */
2969
2970 /* created for use with alloc_percpu */
2971 struct trace_buffer_struct {
2972         int nesting;
2973         char buffer[4][TRACE_BUF_SIZE];
2974 };
2975
2976 static struct trace_buffer_struct *trace_percpu_buffer;
2977
2978 /*
2979  * Thise allows for lockless recording.  If we're nested too deeply, then
2980  * this returns NULL.
2981  */
2982 static char *get_trace_buf(void)
2983 {
2984         struct trace_buffer_struct *buffer = this_cpu_ptr(trace_percpu_buffer);
2985
2986         if (!buffer || buffer->nesting >= 4)
2987                 return NULL;
2988
2989         buffer->nesting++;
2990
2991         /* Interrupts must see nesting incremented before we use the buffer */
2992         barrier();
2993         return &buffer->buffer[buffer->nesting][0];
2994 }
2995
2996 static void put_trace_buf(void)
2997 {
2998         /* Don't let the decrement of nesting leak before this */
2999         barrier();
3000         this_cpu_dec(trace_percpu_buffer->nesting);
3001 }
3002
3003 static int alloc_percpu_trace_buffer(void)
3004 {
3005         struct trace_buffer_struct *buffers;
3006
3007         buffers = alloc_percpu(struct trace_buffer_struct);
3008         if (WARN(!buffers, "Could not allocate percpu trace_printk buffer"))
3009                 return -ENOMEM;
3010
3011         trace_percpu_buffer = buffers;
3012         return 0;
3013 }
3014
3015 static int buffers_allocated;
3016
3017 void trace_printk_init_buffers(void)
3018 {
3019         if (buffers_allocated)
3020                 return;
3021
3022         if (alloc_percpu_trace_buffer())
3023                 return;
3024
3025         /* trace_printk() is for debug use only. Don't use it in production. */
3026
3027         pr_warn("\n");
3028         pr_warn("**********************************************************\n");
3029         pr_warn("**   NOTICE NOTICE NOTICE NOTICE NOTICE NOTICE NOTICE   **\n");
3030         pr_warn("**                                                      **\n");
3031         pr_warn("** trace_printk() being used. Allocating extra memory.  **\n");
3032         pr_warn("**                                                      **\n");
3033         pr_warn("** This means that this is a DEBUG kernel and it is     **\n");
3034         pr_warn("** unsafe for production use.                           **\n");
3035         pr_warn("**                                                      **\n");
3036         pr_warn("** If you see this message and you are not debugging    **\n");
3037         pr_warn("** the kernel, report this immediately to your vendor!  **\n");
3038         pr_warn("**                                                      **\n");
3039         pr_warn("**   NOTICE NOTICE NOTICE NOTICE NOTICE NOTICE NOTICE   **\n");
3040         pr_warn("**********************************************************\n");
3041
3042         /* Expand the buffers to set size */
3043         tracing_update_buffers();
3044
3045         buffers_allocated = 1;
3046
3047         /*
3048          * trace_printk_init_buffers() can be called by modules.
3049          * If that happens, then we need to start cmdline recording
3050          * directly here. If the global_trace.buffer is already
3051          * allocated here, then this was called by module code.
3052          */
3053         if (global_trace.trace_buffer.buffer)
3054                 tracing_start_cmdline_record();
3055 }
3056
3057 void trace_printk_start_comm(void)
3058 {
3059         /* Start tracing comms if trace printk is set */
3060         if (!buffers_allocated)
3061                 return;
3062         tracing_start_cmdline_record();
3063 }
3064
3065 static void trace_printk_start_stop_comm(int enabled)
3066 {
3067         if (!buffers_allocated)
3068                 return;
3069
3070         if (enabled)
3071                 tracing_start_cmdline_record();
3072         else
3073                 tracing_stop_cmdline_record();
3074 }
3075
3076 /**
3077  * trace_vbprintk - write binary msg to tracing buffer
3078  *
3079  */
3080 int trace_vbprintk(unsigned long ip, const char *fmt, va_list args)
3081 {
3082         struct trace_event_call *call = &event_bprint;
3083         struct ring_buffer_event *event;
3084         struct ring_buffer *buffer;
3085         struct trace_array *tr = &global_trace;
3086         struct bprint_entry *entry;
3087         unsigned long flags;
3088         char *tbuffer;
3089         int len = 0, size, pc;
3090
3091         if (unlikely(tracing_selftest_running || tracing_disabled))
3092                 return 0;
3093
3094         /* Don't pollute graph traces with trace_vprintk internals */
3095         pause_graph_tracing();
3096
3097         pc = preempt_count();
3098         preempt_disable_notrace();
3099
3100         tbuffer = get_trace_buf();
3101         if (!tbuffer) {
3102                 len = 0;
3103                 goto out_nobuffer;
3104         }
3105
3106         len = vbin_printf((u32 *)tbuffer, TRACE_BUF_SIZE/sizeof(int), fmt, args);
3107
3108         if (len > TRACE_BUF_SIZE/sizeof(int) || len < 0)
3109                 goto out;
3110
3111         local_save_flags(flags);
3112         size = sizeof(*entry) + sizeof(u32) * len;
3113         buffer = tr->trace_buffer.buffer;
3114         event = __trace_buffer_lock_reserve(buffer, TRACE_BPRINT, size,
3115                                             flags, pc);
3116         if (!event)
3117                 goto out;
3118         entry = ring_buffer_event_data(event);
3119         entry->ip                       = ip;
3120         entry->fmt                      = fmt;
3121
3122         memcpy(entry->buf, tbuffer, sizeof(u32) * len);
3123         if (!call_filter_check_discard(call, entry, buffer, event)) {
3124                 __buffer_unlock_commit(buffer, event);
3125                 ftrace_trace_stack(tr, buffer, flags, 6, pc, NULL);
3126         }
3127
3128 out:
3129         put_trace_buf();
3130
3131 out_nobuffer:
3132         preempt_enable_notrace();
3133         unpause_graph_tracing();
3134
3135         return len;
3136 }
3137 EXPORT_SYMBOL_GPL(trace_vbprintk);
3138
3139 __printf(3, 0)
3140 static int
3141 __trace_array_vprintk(struct ring_buffer *buffer,
3142                       unsigned long ip, const char *fmt, va_list args)
3143 {
3144         struct trace_event_call *call = &event_print;
3145         struct ring_buffer_event *event;
3146         int len = 0, size, pc;
3147         struct print_entry *entry;
3148         unsigned long flags;
3149         char *tbuffer;
3150
3151         if (tracing_disabled || tracing_selftest_running)
3152                 return 0;
3153
3154         /* Don't pollute graph traces with trace_vprintk internals */
3155         pause_graph_tracing();
3156
3157         pc = preempt_count();
3158         preempt_disable_notrace();
3159
3160
3161         tbuffer = get_trace_buf();
3162         if (!tbuffer) {
3163                 len = 0;
3164                 goto out_nobuffer;
3165         }
3166
3167         len = vscnprintf(tbuffer, TRACE_BUF_SIZE, fmt, args);
3168
3169         local_save_flags(flags);
3170         size = sizeof(*entry) + len + 1;
3171         event = __trace_buffer_lock_reserve(buffer, TRACE_PRINT, size,
3172                                             flags, pc);
3173         if (!event)
3174                 goto out;
3175         entry = ring_buffer_event_data(event);
3176         entry->ip = ip;
3177
3178         memcpy(&entry->buf, tbuffer, len + 1);
3179         if (!call_filter_check_discard(call, entry, buffer, event)) {
3180                 __buffer_unlock_commit(buffer, event);
3181                 ftrace_trace_stack(&global_trace, buffer, flags, 6, pc, NULL);
3182         }
3183
3184 out:
3185         put_trace_buf();
3186
3187 out_nobuffer:
3188         preempt_enable_notrace();
3189         unpause_graph_tracing();
3190
3191         return len;
3192 }
3193
3194 __printf(3, 0)
3195 int trace_array_vprintk(struct trace_array *tr,
3196                         unsigned long ip, const char *fmt, va_list args)
3197 {
3198         return __trace_array_vprintk(tr->trace_buffer.buffer, ip, fmt, args);
3199 }
3200
3201 __printf(3, 0)
3202 int trace_array_printk(struct trace_array *tr,
3203                        unsigned long ip, const char *fmt, ...)
3204 {
3205         int ret;
3206         va_list ap;
3207
3208         if (!(global_trace.trace_flags & TRACE_ITER_PRINTK))
3209                 return 0;
3210
3211         va_start(ap, fmt);
3212         ret = trace_array_vprintk(tr, ip, fmt, ap);
3213         va_end(ap);
3214         return ret;
3215 }
3216
3217 __printf(3, 4)
3218 int trace_array_printk_buf(struct ring_buffer *buffer,
3219                            unsigned long ip, const char *fmt, ...)
3220 {
3221         int ret;
3222         va_list ap;
3223
3224         if (!(global_trace.trace_flags & TRACE_ITER_PRINTK))
3225                 return 0;
3226
3227         va_start(ap, fmt);
3228         ret = __trace_array_vprintk(buffer, ip, fmt, ap);
3229         va_end(ap);
3230         return ret;
3231 }
3232
3233 __printf(2, 0)
3234 int trace_vprintk(unsigned long ip, const char *fmt, va_list args)
3235 {
3236         return trace_array_vprintk(&global_trace, ip, fmt, args);
3237 }
3238 EXPORT_SYMBOL_GPL(trace_vprintk);
3239
3240 static void trace_iterator_increment(struct trace_iterator *iter)
3241 {
3242         struct ring_buffer_iter *buf_iter = trace_buffer_iter(iter, iter->cpu);
3243
3244         iter->idx++;
3245         if (buf_iter)
3246                 ring_buffer_read(buf_iter, NULL);
3247 }
3248
3249 static struct trace_entry *
3250 peek_next_entry(struct trace_iterator *iter, int cpu, u64 *ts,
3251                 unsigned long *lost_events)
3252 {
3253         struct ring_buffer_event *event;
3254         struct ring_buffer_iter *buf_iter = trace_buffer_iter(iter, cpu);
3255
3256         if (buf_iter)
3257                 event = ring_buffer_iter_peek(buf_iter, ts);
3258         else
3259                 event = ring_buffer_peek(iter->trace_buffer->buffer, cpu, ts,
3260                                          lost_events);
3261
3262         if (event) {
3263                 iter->ent_size = ring_buffer_event_length(event);
3264                 return ring_buffer_event_data(event);
3265         }
3266         iter->ent_size = 0;
3267         return NULL;
3268 }
3269
3270 static struct trace_entry *
3271 __find_next_entry(struct trace_iterator *iter, int *ent_cpu,
3272                   unsigned long *missing_events, u64 *ent_ts)
3273 {
3274         struct ring_buffer *buffer = iter->trace_buffer->buffer;
3275         struct trace_entry *ent, *next = NULL;
3276         unsigned long lost_events = 0, next_lost = 0;
3277         int cpu_file = iter->cpu_file;
3278         u64 next_ts = 0, ts;
3279         int next_cpu = -1;
3280         int next_size = 0;
3281         int cpu;
3282
3283         /*
3284          * If we are in a per_cpu trace file, don't bother by iterating over
3285          * all cpu and peek directly.
3286          */
3287         if (cpu_file > RING_BUFFER_ALL_CPUS) {
3288                 if (ring_buffer_empty_cpu(buffer, cpu_file))
3289                         return NULL;
3290                 ent = peek_next_entry(iter, cpu_file, ent_ts, missing_events);
3291                 if (ent_cpu)
3292                         *ent_cpu = cpu_file;
3293
3294                 return ent;
3295         }
3296
3297         for_each_tracing_cpu(cpu) {
3298
3299                 if (ring_buffer_empty_cpu(buffer, cpu))
3300                         continue;
3301
3302                 ent = peek_next_entry(iter, cpu, &ts, &lost_events);
3303
3304                 /*
3305                  * Pick the entry with the smallest timestamp:
3306                  */
3307                 if (ent && (!next || ts < next_ts)) {
3308                         next = ent;
3309                         next_cpu = cpu;
3310                         next_ts = ts;
3311                         next_lost = lost_events;
3312                         next_size = iter->ent_size;
3313                 }
3314         }
3315
3316         iter->ent_size = next_size;
3317
3318         if (ent_cpu)
3319                 *ent_cpu = next_cpu;
3320
3321         if (ent_ts)
3322                 *ent_ts = next_ts;
3323
3324         if (missing_events)
3325                 *missing_events = next_lost;
3326
3327         return next;
3328 }
3329
3330 /* Find the next real entry, without updating the iterator itself */
3331 struct trace_entry *trace_find_next_entry(struct trace_iterator *iter,
3332                                           int *ent_cpu, u64 *ent_ts)
3333 {
3334         return __find_next_entry(iter, ent_cpu, NULL, ent_ts);
3335 }
3336
3337 /* Find the next real entry, and increment the iterator to the next entry */
3338 void *trace_find_next_entry_inc(struct trace_iterator *iter)
3339 {
3340         iter->ent = __find_next_entry(iter, &iter->cpu,
3341                                       &iter->lost_events, &iter->ts);
3342
3343         if (iter->ent)
3344                 trace_iterator_increment(iter);
3345
3346         return iter->ent ? iter : NULL;
3347 }
3348
3349 static void trace_consume(struct trace_iterator *iter)
3350 {
3351         ring_buffer_consume(iter->trace_buffer->buffer, iter->cpu, &iter->ts,
3352                             &iter->lost_events);
3353 }
3354
3355 static void *s_next(struct seq_file *m, void *v, loff_t *pos)
3356 {
3357         struct trace_iterator *iter = m->private;
3358         int i = (int)*pos;
3359         void *ent;
3360
3361         WARN_ON_ONCE(iter->leftover);
3362
3363         (*pos)++;
3364
3365         /* can't go backwards */
3366         if (iter->idx > i)
3367                 return NULL;
3368
3369         if (iter->idx < 0)
3370                 ent = trace_find_next_entry_inc(iter);
3371         else
3372                 ent = iter;
3373
3374         while (ent && iter->idx < i)
3375                 ent = trace_find_next_entry_inc(iter);
3376
3377         iter->pos = *pos;
3378
3379         return ent;
3380 }
3381
3382 void tracing_iter_reset(struct trace_iterator *iter, int cpu)
3383 {
3384         struct ring_buffer_event *event;
3385         struct ring_buffer_iter *buf_iter;
3386         unsigned long entries = 0;
3387         u64 ts;
3388
3389         per_cpu_ptr(iter->trace_buffer->data, cpu)->skipped_entries = 0;
3390
3391         buf_iter = trace_buffer_iter(iter, cpu);
3392         if (!buf_iter)
3393                 return;
3394
3395         ring_buffer_iter_reset(buf_iter);
3396
3397         /*
3398          * We could have the case with the max latency tracers
3399          * that a reset never took place on a cpu. This is evident
3400          * by the timestamp being before the start of the buffer.
3401          */
3402         while ((event = ring_buffer_iter_peek(buf_iter, &ts))) {
3403                 if (ts >= iter->trace_buffer->time_start)
3404                         break;
3405                 entries++;
3406                 ring_buffer_read(buf_iter, NULL);
3407         }
3408
3409         per_cpu_ptr(iter->trace_buffer->data, cpu)->skipped_entries = entries;
3410 }
3411
3412 /*
3413  * The current tracer is copied to avoid a global locking
3414  * all around.
3415  */
3416 static void *s_start(struct seq_file *m, loff_t *pos)
3417 {
3418         struct trace_iterator *iter = m->private;
3419         struct trace_array *tr = iter->tr;
3420         int cpu_file = iter->cpu_file;
3421         void *p = NULL;
3422         loff_t l = 0;
3423         int cpu;
3424
3425         /*
3426          * copy the tracer to avoid using a global lock all around.
3427          * iter->trace is a copy of current_trace, the pointer to the
3428          * name may be used instead of a strcmp(), as iter->trace->name
3429          * will point to the same string as current_trace->name.
3430          */
3431         mutex_lock(&trace_types_lock);
3432         if (unlikely(tr->current_trace && iter->trace->name != tr->current_trace->name))
3433                 *iter->trace = *tr->current_trace;
3434         mutex_unlock(&trace_types_lock);
3435
3436 #ifdef CONFIG_TRACER_MAX_TRACE
3437         if (iter->snapshot && iter->trace->use_max_tr)
3438                 return ERR_PTR(-EBUSY);
3439 #endif
3440
3441         if (!iter->snapshot)
3442                 atomic_inc(&trace_record_taskinfo_disabled);
3443
3444         if (*pos != iter->pos) {
3445                 iter->ent = NULL;
3446                 iter->cpu = 0;
3447                 iter->idx = -1;
3448
3449                 if (cpu_file == RING_BUFFER_ALL_CPUS) {
3450                         for_each_tracing_cpu(cpu)
3451                                 tracing_iter_reset(iter, cpu);
3452                 } else
3453                         tracing_iter_reset(iter, cpu_file);
3454
3455                 iter->leftover = 0;
3456                 for (p = iter; p && l < *pos; p = s_next(m, p, &l))
3457                         ;
3458
3459         } else {
3460                 /*
3461                  * If we overflowed the seq_file before, then we want
3462                  * to just reuse the trace_seq buffer again.
3463                  */
3464                 if (iter->leftover)
3465                         p = iter;
3466                 else {
3467                         l = *pos - 1;
3468                         p = s_next(m, p, &l);
3469                 }
3470         }
3471
3472         trace_event_read_lock();
3473         trace_access_lock(cpu_file);
3474         return p;
3475 }
3476
3477 static void s_stop(struct seq_file *m, void *p)
3478 {
3479         struct trace_iterator *iter = m->private;
3480
3481 #ifdef CONFIG_TRACER_MAX_TRACE
3482         if (iter->snapshot && iter->trace->use_max_tr)
3483                 return;
3484 #endif
3485
3486         if (!iter->snapshot)
3487                 atomic_dec(&trace_record_taskinfo_disabled);
3488
3489         trace_access_unlock(iter->cpu_file);
3490         trace_event_read_unlock();
3491 }
3492
3493 static void
3494 get_total_entries(struct trace_buffer *buf,
3495                   unsigned long *total, unsigned long *entries)
3496 {
3497         unsigned long count;
3498         int cpu;
3499
3500         *total = 0;
3501         *entries = 0;
3502
3503         for_each_tracing_cpu(cpu) {
3504                 count = ring_buffer_entries_cpu(buf->buffer, cpu);
3505                 /*
3506                  * If this buffer has skipped entries, then we hold all
3507                  * entries for the trace and we need to ignore the
3508                  * ones before the time stamp.
3509                  */
3510                 if (per_cpu_ptr(buf->data, cpu)->skipped_entries) {
3511                         count -= per_cpu_ptr(buf->data, cpu)->skipped_entries;
3512                         /* total is the same as the entries */
3513                         *total += count;
3514                 } else
3515                         *total += count +
3516                                 ring_buffer_overrun_cpu(buf->buffer, cpu);
3517                 *entries += count;
3518         }
3519 }
3520
3521 static void print_lat_help_header(struct seq_file *m)
3522 {
3523         seq_puts(m, "#                  _------=> CPU#            \n"
3524                     "#                 / _-----=> irqs-off        \n"
3525                     "#                | / _----=> need-resched    \n"
3526                     "#                || / _---=> hardirq/softirq \n"
3527                     "#                ||| / _--=> preempt-depth   \n"
3528                     "#                |||| /     delay            \n"
3529                     "#  cmd     pid   ||||| time  |   caller      \n"
3530                     "#     \\   /      |||||  \\    |   /         \n");
3531 }
3532
3533 static void print_event_info(struct trace_buffer *buf, struct seq_file *m)
3534 {
3535         unsigned long total;
3536         unsigned long entries;
3537
3538         get_total_entries(buf, &total, &entries);
3539         seq_printf(m, "# entries-in-buffer/entries-written: %lu/%lu   #P:%d\n",
3540                    entries, total, num_online_cpus());
3541         seq_puts(m, "#\n");
3542 }
3543
3544 static void print_func_help_header(struct trace_buffer *buf, struct seq_file *m,
3545                                    unsigned int flags)
3546 {
3547         bool tgid = flags & TRACE_ITER_RECORD_TGID;
3548
3549         print_event_info(buf, m);
3550
3551         seq_printf(m, "#           TASK-PID   %s  CPU#   TIMESTAMP  FUNCTION\n", tgid ? "TGID     " : "");
3552         seq_printf(m, "#              | |     %s    |       |         |\n",      tgid ? "  |      " : "");
3553 }
3554
3555 static void print_func_help_header_irq(struct trace_buffer *buf, struct seq_file *m,
3556                                        unsigned int flags)
3557 {
3558         bool tgid = flags & TRACE_ITER_RECORD_TGID;
3559         const char tgid_space[] = "          ";
3560         const char space[] = "  ";
3561
3562         print_event_info(buf, m);
3563
3564         seq_printf(m, "#                          %s  _-----=> irqs-off\n",
3565                    tgid ? tgid_space : space);
3566         seq_printf(m, "#                          %s / _----=> need-resched\n",
3567                    tgid ? tgid_space : space);
3568         seq_printf(m, "#                          %s| / _---=> hardirq/softirq\n",
3569                    tgid ? tgid_space : space);
3570         seq_printf(m, "#                          %s|| / _--=> preempt-depth\n",
3571                    tgid ? tgid_space : space);
3572         seq_printf(m, "#                          %s||| /     delay\n",
3573                    tgid ? tgid_space : space);
3574         seq_printf(m, "#           TASK-PID %sCPU#  ||||    TIMESTAMP  FUNCTION\n",
3575                    tgid ? "   TGID   " : space);
3576         seq_printf(m, "#              | |   %s  |   ||||       |         |\n",
3577                    tgid ? "     |    " : space);
3578 }
3579
3580 void
3581 print_trace_header(struct seq_file *m, struct trace_iterator *iter)
3582 {
3583         unsigned long sym_flags = (global_trace.trace_flags & TRACE_ITER_SYM_MASK);
3584         struct trace_buffer *buf = iter->trace_buffer;
3585         struct trace_array_cpu *data = per_cpu_ptr(buf->data, buf->cpu);
3586         struct tracer *type = iter->trace;
3587         unsigned long entries;
3588         unsigned long total;
3589         const char *name = "preemption";
3590
3591         name = type->name;
3592
3593         get_total_entries(buf, &total, &entries);
3594
3595         seq_printf(m, "# %s latency trace v1.1.5 on %s\n",
3596                    name, UTS_RELEASE);
3597         seq_puts(m, "# -----------------------------------"
3598                  "---------------------------------\n");
3599         seq_printf(m, "# latency: %lu us, #%lu/%lu, CPU#%d |"
3600                    " (M:%s VP:%d, KP:%d, SP:%d HP:%d",
3601                    nsecs_to_usecs(data->saved_latency),
3602                    entries,
3603                    total,
3604                    buf->cpu,
3605 #if defined(CONFIG_PREEMPT_NONE)
3606                    "server",
3607 #elif defined(CONFIG_PREEMPT_VOLUNTARY)
3608                    "desktop",
3609 #elif defined(CONFIG_PREEMPT)
3610                    "preempt",
3611 #else
3612                    "unknown",
3613 #endif
3614                    /* These are reserved for later use */
3615                    0, 0, 0, 0);
3616 #ifdef CONFIG_SMP
3617         seq_printf(m, " #P:%d)\n", num_online_cpus());
3618 #else
3619         seq_puts(m, ")\n");
3620 #endif
3621         seq_puts(m, "#    -----------------\n");
3622         seq_printf(m, "#    | task: %.16s-%d "
3623                    "(uid:%d nice:%ld policy:%ld rt_prio:%ld)\n",
3624                    data->comm, data->pid,
3625                    from_kuid_munged(seq_user_ns(m), data->uid), data->nice,
3626                    data->policy, data->rt_priority);
3627         seq_puts(m, "#    -----------------\n");
3628
3629         if (data->critical_start) {
3630                 seq_puts(m, "#  => started at: ");
3631                 seq_print_ip_sym(&iter->seq, data->critical_start, sym_flags);
3632                 trace_print_seq(m, &iter->seq);
3633                 seq_puts(m, "\n#  => ended at:   ");
3634                 seq_print_ip_sym(&iter->seq, data->critical_end, sym_flags);
3635                 trace_print_seq(m, &iter->seq);
3636                 seq_puts(m, "\n#\n");
3637         }
3638
3639         seq_puts(m, "#\n");
3640 }
3641
3642 static void test_cpu_buff_start(struct trace_iterator *iter)
3643 {
3644         struct trace_seq *s = &iter->seq;
3645         struct trace_array *tr = iter->tr;
3646
3647         if (!(tr->trace_flags & TRACE_ITER_ANNOTATE))
3648                 return;
3649
3650         if (!(iter->iter_flags & TRACE_FILE_ANNOTATE))
3651                 return;
3652
3653         if (cpumask_available(iter->started) &&
3654             cpumask_test_cpu(iter->cpu, iter->started))
3655                 return;
3656
3657         if (per_cpu_ptr(iter->trace_buffer->data, iter->cpu)->skipped_entries)
3658                 return;
3659
3660         if (cpumask_available(iter->started))
3661                 cpumask_set_cpu(iter->cpu, iter->started);
3662
3663         /* Don't print started cpu buffer for the first entry of the trace */
3664         if (iter->idx > 1)
3665                 trace_seq_printf(s, "##### CPU %u buffer started ####\n",
3666                                 iter->cpu);
3667 }
3668
3669 static enum print_line_t print_trace_fmt(struct trace_iterator *iter)
3670 {
3671         struct trace_array *tr = iter->tr;
3672         struct trace_seq *s = &iter->seq;
3673         unsigned long sym_flags = (tr->trace_flags & TRACE_ITER_SYM_MASK);
3674         struct trace_entry *entry;
3675         struct trace_event *event;
3676
3677         entry = iter->ent;
3678
3679         test_cpu_buff_start(iter);
3680
3681         event = ftrace_find_event(entry->type);
3682
3683         if (tr->trace_flags & TRACE_ITER_CONTEXT_INFO) {
3684                 if (iter->iter_flags & TRACE_FILE_LAT_FMT)
3685                         trace_print_lat_context(iter);
3686                 else
3687                         trace_print_context(iter);
3688         }
3689
3690         if (trace_seq_has_overflowed(s))
3691                 return TRACE_TYPE_PARTIAL_LINE;
3692
3693         if (event)
3694                 return event->funcs->trace(iter, sym_flags, event);
3695
3696         trace_seq_printf(s, "Unknown type %d\n", entry->type);
3697
3698         return trace_handle_return(s);
3699 }
3700
3701 static enum print_line_t print_raw_fmt(struct trace_iterator *iter)
3702 {
3703         struct trace_array *tr = iter->tr;
3704         struct trace_seq *s = &iter->seq;
3705         struct trace_entry *entry;
3706         struct trace_event *event;
3707
3708         entry = iter->ent;
3709
3710         if (tr->trace_flags & TRACE_ITER_CONTEXT_INFO)
3711                 trace_seq_printf(s, "%d %d %llu ",
3712                                  entry->pid, iter->cpu, iter->ts);
3713
3714         if (trace_seq_has_overflowed(s))
3715                 return TRACE_TYPE_PARTIAL_LINE;
3716
3717         event = ftrace_find_event(entry->type);
3718         if (event)
3719                 return event->funcs->raw(iter, 0, event);
3720
3721         trace_seq_printf(s, "%d ?\n", entry->type);
3722
3723         return trace_handle_return(s);
3724 }
3725
3726 static enum print_line_t print_hex_fmt(struct trace_iterator *iter)
3727 {
3728         struct trace_array *tr = iter->tr;
3729         struct trace_seq *s = &iter->seq;
3730         unsigned char newline = '\n';
3731         struct trace_entry *entry;
3732         struct trace_event *event;
3733
3734         entry = iter->ent;
3735
3736         if (tr->trace_flags & TRACE_ITER_CONTEXT_INFO) {
3737                 SEQ_PUT_HEX_FIELD(s, entry->pid);
3738                 SEQ_PUT_HEX_FIELD(s, iter->cpu);
3739                 SEQ_PUT_HEX_FIELD(s, iter->ts);
3740                 if (trace_seq_has_overflowed(s))
3741                         return TRACE_TYPE_PARTIAL_LINE;
3742         }
3743
3744         event = ftrace_find_event(entry->type);
3745         if (event) {
3746                 enum print_line_t ret = event->funcs->hex(iter, 0, event);
3747                 if (ret != TRACE_TYPE_HANDLED)
3748                         return ret;
3749         }
3750
3751         SEQ_PUT_FIELD(s, newline);
3752
3753         return trace_handle_return(s);
3754 }
3755
3756 static enum print_line_t print_bin_fmt(struct trace_iterator *iter)
3757 {
3758         struct trace_array *tr = iter->tr;
3759         struct trace_seq *s = &iter->seq;
3760         struct trace_entry *entry;
3761         struct trace_event *event;
3762
3763         entry = iter->ent;
3764
3765         if (tr->trace_flags & TRACE_ITER_CONTEXT_INFO) {
3766                 SEQ_PUT_FIELD(s, entry->pid);
3767                 SEQ_PUT_FIELD(s, iter->cpu);
3768                 SEQ_PUT_FIELD(s, iter->ts);
3769                 if (trace_seq_has_overflowed(s))
3770                         return TRACE_TYPE_PARTIAL_LINE;
3771         }
3772
3773         event = ftrace_find_event(entry->type);
3774         return event ? event->funcs->binary(iter, 0, event) :
3775                 TRACE_TYPE_HANDLED;
3776 }
3777
3778 int trace_empty(struct trace_iterator *iter)
3779 {
3780         struct ring_buffer_iter *buf_iter;
3781         int cpu;
3782
3783         /* If we are looking at one CPU buffer, only check that one */
3784         if (iter->cpu_file != RING_BUFFER_ALL_CPUS) {
3785                 cpu = iter->cpu_file;
3786                 buf_iter = trace_buffer_iter(iter, cpu);
3787                 if (buf_iter) {
3788                         if (!ring_buffer_iter_empty(buf_iter))
3789                                 return 0;
3790                 } else {
3791                         if (!ring_buffer_empty_cpu(iter->trace_buffer->buffer, cpu))
3792                                 return 0;
3793                 }
3794                 return 1;
3795         }
3796
3797         for_each_tracing_cpu(cpu) {
3798                 buf_iter = trace_buffer_iter(iter, cpu);
3799                 if (buf_iter) {
3800                         if (!ring_buffer_iter_empty(buf_iter))
3801                                 return 0;
3802                 } else {
3803                         if (!ring_buffer_empty_cpu(iter->trace_buffer->buffer, cpu))
3804                                 return 0;
3805                 }
3806         }
3807
3808         return 1;
3809 }
3810
3811 /*  Called with trace_event_read_lock() held. */
3812 enum print_line_t print_trace_line(struct trace_iterator *iter)
3813 {
3814         struct trace_array *tr = iter->tr;
3815         unsigned long trace_flags = tr->trace_flags;
3816         enum print_line_t ret;
3817
3818         if (iter->lost_events) {
3819                 trace_seq_printf(&iter->seq, "CPU:%d [LOST %lu EVENTS]\n",
3820                                  iter->cpu, iter->lost_events);
3821                 if (trace_seq_has_overflowed(&iter->seq))
3822                         return TRACE_TYPE_PARTIAL_LINE;
3823         }
3824
3825         if (iter->trace && iter->trace->print_line) {
3826                 ret = iter->trace->print_line(iter);
3827                 if (ret != TRACE_TYPE_UNHANDLED)
3828                         return ret;
3829         }
3830
3831         if (iter->ent->type == TRACE_BPUTS &&
3832                         trace_flags & TRACE_ITER_PRINTK &&
3833                         trace_flags & TRACE_ITER_PRINTK_MSGONLY)
3834                 return trace_print_bputs_msg_only(iter);
3835
3836         if (iter->ent->type == TRACE_BPRINT &&
3837                         trace_flags & TRACE_ITER_PRINTK &&
3838                         trace_flags & TRACE_ITER_PRINTK_MSGONLY)
3839                 return trace_print_bprintk_msg_only(iter);
3840
3841         if (iter->ent->type == TRACE_PRINT &&
3842                         trace_flags & TRACE_ITER_PRINTK &&
3843                         trace_flags & TRACE_ITER_PRINTK_MSGONLY)
3844                 return trace_print_printk_msg_only(iter);
3845
3846         if (trace_flags & TRACE_ITER_BIN)
3847                 return print_bin_fmt(iter);
3848
3849         if (trace_flags & TRACE_ITER_HEX)
3850                 return print_hex_fmt(iter);
3851
3852         if (trace_flags & TRACE_ITER_RAW)
3853                 return print_raw_fmt(iter);
3854
3855         return print_trace_fmt(iter);
3856 }
3857
3858 void trace_latency_header(struct seq_file *m)
3859 {
3860         struct trace_iterator *iter = m->private;
3861         struct trace_array *tr = iter->tr;
3862
3863         /* print nothing if the buffers are empty */
3864         if (trace_empty(iter))
3865                 return;
3866
3867         if (iter->iter_flags & TRACE_FILE_LAT_FMT)
3868                 print_trace_header(m, iter);
3869
3870         if (!(tr->trace_flags & TRACE_ITER_VERBOSE))
3871                 print_lat_help_header(m);
3872 }
3873
3874 void trace_default_header(struct seq_file *m)
3875 {
3876         struct trace_iterator *iter = m->private;
3877         struct trace_array *tr = iter->tr;
3878         unsigned long trace_flags = tr->trace_flags;
3879
3880         if (!(trace_flags & TRACE_ITER_CONTEXT_INFO))
3881                 return;
3882
3883         if (iter->iter_flags & TRACE_FILE_LAT_FMT) {
3884                 /* print nothing if the buffers are empty */
3885                 if (trace_empty(iter))
3886                         return;
3887                 print_trace_header(m, iter);
3888                 if (!(trace_flags & TRACE_ITER_VERBOSE))
3889                         print_lat_help_header(m);
3890         } else {
3891                 if (!(trace_flags & TRACE_ITER_VERBOSE)) {
3892                         if (trace_flags & TRACE_ITER_IRQ_INFO)
3893                                 print_func_help_header_irq(iter->trace_buffer,
3894                                                            m, trace_flags);
3895                         else
3896                                 print_func_help_header(iter->trace_buffer, m,
3897                                                        trace_flags);
3898                 }
3899         }
3900 }
3901
3902 static void test_ftrace_alive(struct seq_file *m)
3903 {
3904         if (!ftrace_is_dead())
3905                 return;
3906         seq_puts(m, "# WARNING: FUNCTION TRACING IS CORRUPTED\n"
3907                     "#          MAY BE MISSING FUNCTION EVENTS\n");
3908 }
3909
3910 #ifdef CONFIG_TRACER_MAX_TRACE
3911 static void show_snapshot_main_help(struct seq_file *m)
3912 {
3913         seq_puts(m, "# echo 0 > snapshot : Clears and frees snapshot buffer\n"
3914                     "# echo 1 > snapshot : Allocates snapshot buffer, if not already allocated.\n"
3915                     "#                      Takes a snapshot of the main buffer.\n"
3916                     "# echo 2 > snapshot : Clears snapshot buffer (but does not allocate or free)\n"
3917                     "#                      (Doesn't have to be '2' works with any number that\n"
3918                     "#                       is not a '0' or '1')\n");
3919 }
3920
3921 static void show_snaps