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1 /*
2  * ring buffer based function tracer
3  *
4  * Copyright (C) 2007-2008 Steven Rostedt <srostedt@redhat.com>
5  * Copyright (C) 2008 Ingo Molnar <mingo@redhat.com>
6  *
7  * Originally taken from the RT patch by:
8  *    Arnaldo Carvalho de Melo <acme@redhat.com>
9  *
10  * Based on code from the latency_tracer, that is:
11  *  Copyright (C) 2004-2006 Ingo Molnar
12  *  Copyright (C) 2004 William Lee Irwin III
13  */
14 #include <linux/ring_buffer.h>
15 #include <linux/utsrelease.h>
16 #include <linux/stacktrace.h>
17 #include <linux/writeback.h>
18 #include <linux/kallsyms.h>
19 #include <linux/seq_file.h>
20 #include <linux/notifier.h>
21 #include <linux/irqflags.h>
22 #include <linux/debugfs.h>
23 #include <linux/pagemap.h>
24 #include <linux/hardirq.h>
25 #include <linux/linkage.h>
26 #include <linux/uaccess.h>
27 #include <linux/kprobes.h>
28 #include <linux/ftrace.h>
29 #include <linux/module.h>
30 #include <linux/percpu.h>
31 #include <linux/splice.h>
32 #include <linux/kdebug.h>
33 #include <linux/string.h>
34 #include <linux/ctype.h>
35 #include <linux/init.h>
36 #include <linux/poll.h>
37 #include <linux/gfp.h>
38 #include <linux/fs.h>
39
40 #include "trace.h"
41 #include "trace_output.h"
42
43 #define TRACE_BUFFER_FLAGS      (RB_FL_OVERWRITE)
44
45 unsigned long __read_mostly     tracing_max_latency;
46 unsigned long __read_mostly     tracing_thresh;
47
48 /*
49  * On boot up, the ring buffer is set to the minimum size, so that
50  * we do not waste memory on systems that are not using tracing.
51  */
52 static int ring_buffer_expanded;
53
54 /*
55  * We need to change this state when a selftest is running.
56  * A selftest will lurk into the ring-buffer to count the
57  * entries inserted during the selftest although some concurrent
58  * insertions into the ring-buffer such as trace_printk could occurred
59  * at the same time, giving false positive or negative results.
60  */
61 static bool __read_mostly tracing_selftest_running;
62
63 /*
64  * If a tracer is running, we do not want to run SELFTEST.
65  */
66 static bool __read_mostly tracing_selftest_disabled;
67
68 /* For tracers that don't implement custom flags */
69 static struct tracer_opt dummy_tracer_opt[] = {
70         { }
71 };
72
73 static struct tracer_flags dummy_tracer_flags = {
74         .val = 0,
75         .opts = dummy_tracer_opt
76 };
77
78 static int dummy_set_flag(u32 old_flags, u32 bit, int set)
79 {
80         return 0;
81 }
82
83 /*
84  * Kill all tracing for good (never come back).
85  * It is initialized to 1 but will turn to zero if the initialization
86  * of the tracer is successful. But that is the only place that sets
87  * this back to zero.
88  */
89 static int tracing_disabled = 1;
90
91 static DEFINE_PER_CPU(local_t, ftrace_cpu_disabled);
92
93 static inline void ftrace_disable_cpu(void)
94 {
95         preempt_disable();
96         local_inc(&__get_cpu_var(ftrace_cpu_disabled));
97 }
98
99 static inline void ftrace_enable_cpu(void)
100 {
101         local_dec(&__get_cpu_var(ftrace_cpu_disabled));
102         preempt_enable();
103 }
104
105 static cpumask_var_t __read_mostly      tracing_buffer_mask;
106
107 /* Define which cpu buffers are currently read in trace_pipe */
108 static cpumask_var_t                    tracing_reader_cpumask;
109
110 #define for_each_tracing_cpu(cpu)       \
111         for_each_cpu(cpu, tracing_buffer_mask)
112
113 /*
114  * ftrace_dump_on_oops - variable to dump ftrace buffer on oops
115  *
116  * If there is an oops (or kernel panic) and the ftrace_dump_on_oops
117  * is set, then ftrace_dump is called. This will output the contents
118  * of the ftrace buffers to the console.  This is very useful for
119  * capturing traces that lead to crashes and outputing it to a
120  * serial console.
121  *
122  * It is default off, but you can enable it with either specifying
123  * "ftrace_dump_on_oops" in the kernel command line, or setting
124  * /proc/sys/kernel/ftrace_dump_on_oops to true.
125  */
126 int ftrace_dump_on_oops;
127
128 static int tracing_set_tracer(const char *buf);
129
130 #define BOOTUP_TRACER_SIZE              100
131 static char bootup_tracer_buf[BOOTUP_TRACER_SIZE] __initdata;
132 static char *default_bootup_tracer;
133
134 static int __init set_ftrace(char *str)
135 {
136         strncpy(bootup_tracer_buf, str, BOOTUP_TRACER_SIZE);
137         default_bootup_tracer = bootup_tracer_buf;
138         /* We are using ftrace early, expand it */
139         ring_buffer_expanded = 1;
140         return 1;
141 }
142 __setup("ftrace=", set_ftrace);
143
144 static int __init set_ftrace_dump_on_oops(char *str)
145 {
146         ftrace_dump_on_oops = 1;
147         return 1;
148 }
149 __setup("ftrace_dump_on_oops", set_ftrace_dump_on_oops);
150
151 unsigned long long ns2usecs(cycle_t nsec)
152 {
153         nsec += 500;
154         do_div(nsec, 1000);
155         return nsec;
156 }
157
158 /*
159  * The global_trace is the descriptor that holds the tracing
160  * buffers for the live tracing. For each CPU, it contains
161  * a link list of pages that will store trace entries. The
162  * page descriptor of the pages in the memory is used to hold
163  * the link list by linking the lru item in the page descriptor
164  * to each of the pages in the buffer per CPU.
165  *
166  * For each active CPU there is a data field that holds the
167  * pages for the buffer for that CPU. Each CPU has the same number
168  * of pages allocated for its buffer.
169  */
170 static struct trace_array       global_trace;
171
172 static DEFINE_PER_CPU(struct trace_array_cpu, global_trace_cpu);
173
174 cycle_t ftrace_now(int cpu)
175 {
176         u64 ts;
177
178         /* Early boot up does not have a buffer yet */
179         if (!global_trace.buffer)
180                 return trace_clock_local();
181
182         ts = ring_buffer_time_stamp(global_trace.buffer, cpu);
183         ring_buffer_normalize_time_stamp(global_trace.buffer, cpu, &ts);
184
185         return ts;
186 }
187
188 /*
189  * The max_tr is used to snapshot the global_trace when a maximum
190  * latency is reached. Some tracers will use this to store a maximum
191  * trace while it continues examining live traces.
192  *
193  * The buffers for the max_tr are set up the same as the global_trace.
194  * When a snapshot is taken, the link list of the max_tr is swapped
195  * with the link list of the global_trace and the buffers are reset for
196  * the global_trace so the tracing can continue.
197  */
198 static struct trace_array       max_tr;
199
200 static DEFINE_PER_CPU(struct trace_array_cpu, max_data);
201
202 /* tracer_enabled is used to toggle activation of a tracer */
203 static int                      tracer_enabled = 1;
204
205 /**
206  * tracing_is_enabled - return tracer_enabled status
207  *
208  * This function is used by other tracers to know the status
209  * of the tracer_enabled flag.  Tracers may use this function
210  * to know if it should enable their features when starting
211  * up. See irqsoff tracer for an example (start_irqsoff_tracer).
212  */
213 int tracing_is_enabled(void)
214 {
215         return tracer_enabled;
216 }
217
218 /*
219  * trace_buf_size is the size in bytes that is allocated
220  * for a buffer. Note, the number of bytes is always rounded
221  * to page size.
222  *
223  * This number is purposely set to a low number of 16384.
224  * If the dump on oops happens, it will be much appreciated
225  * to not have to wait for all that output. Anyway this can be
226  * boot time and run time configurable.
227  */
228 #define TRACE_BUF_SIZE_DEFAULT  1441792UL /* 16384 * 88 (sizeof(entry)) */
229
230 static unsigned long            trace_buf_size = TRACE_BUF_SIZE_DEFAULT;
231
232 /* trace_types holds a link list of available tracers. */
233 static struct tracer            *trace_types __read_mostly;
234
235 /* current_trace points to the tracer that is currently active */
236 static struct tracer            *current_trace __read_mostly;
237
238 /*
239  * max_tracer_type_len is used to simplify the allocating of
240  * buffers to read userspace tracer names. We keep track of
241  * the longest tracer name registered.
242  */
243 static int                      max_tracer_type_len;
244
245 /*
246  * trace_types_lock is used to protect the trace_types list.
247  * This lock is also used to keep user access serialized.
248  * Accesses from userspace will grab this lock while userspace
249  * activities happen inside the kernel.
250  */
251 static DEFINE_MUTEX(trace_types_lock);
252
253 /* trace_wait is a waitqueue for tasks blocked on trace_poll */
254 static DECLARE_WAIT_QUEUE_HEAD(trace_wait);
255
256 /* trace_flags holds trace_options default values */
257 unsigned long trace_flags = TRACE_ITER_PRINT_PARENT | TRACE_ITER_PRINTK |
258         TRACE_ITER_ANNOTATE | TRACE_ITER_CONTEXT_INFO | TRACE_ITER_SLEEP_TIME;
259
260 /**
261  * trace_wake_up - wake up tasks waiting for trace input
262  *
263  * Simply wakes up any task that is blocked on the trace_wait
264  * queue. These is used with trace_poll for tasks polling the trace.
265  */
266 void trace_wake_up(void)
267 {
268         /*
269          * The runqueue_is_locked() can fail, but this is the best we
270          * have for now:
271          */
272         if (!(trace_flags & TRACE_ITER_BLOCK) && !runqueue_is_locked())
273                 wake_up(&trace_wait);
274 }
275
276 static int __init set_buf_size(char *str)
277 {
278         unsigned long buf_size;
279         int ret;
280
281         if (!str)
282                 return 0;
283         ret = strict_strtoul(str, 0, &buf_size);
284         /* nr_entries can not be zero */
285         if (ret < 0 || buf_size == 0)
286                 return 0;
287         trace_buf_size = buf_size;
288         return 1;
289 }
290 __setup("trace_buf_size=", set_buf_size);
291
292 unsigned long nsecs_to_usecs(unsigned long nsecs)
293 {
294         return nsecs / 1000;
295 }
296
297 /* These must match the bit postions in trace_iterator_flags */
298 static const char *trace_options[] = {
299         "print-parent",
300         "sym-offset",
301         "sym-addr",
302         "verbose",
303         "raw",
304         "hex",
305         "bin",
306         "block",
307         "stacktrace",
308         "sched-tree",
309         "trace_printk",
310         "ftrace_preempt",
311         "branch",
312         "annotate",
313         "userstacktrace",
314         "sym-userobj",
315         "printk-msg-only",
316         "context-info",
317         "latency-format",
318         "global-clock",
319         "sleep-time",
320         NULL
321 };
322
323 /*
324  * ftrace_max_lock is used to protect the swapping of buffers
325  * when taking a max snapshot. The buffers themselves are
326  * protected by per_cpu spinlocks. But the action of the swap
327  * needs its own lock.
328  *
329  * This is defined as a raw_spinlock_t in order to help
330  * with performance when lockdep debugging is enabled.
331  */
332 static raw_spinlock_t ftrace_max_lock =
333         (raw_spinlock_t)__RAW_SPIN_LOCK_UNLOCKED;
334
335 /*
336  * Copy the new maximum trace into the separate maximum-trace
337  * structure. (this way the maximum trace is permanently saved,
338  * for later retrieval via /debugfs/tracing/latency_trace)
339  */
340 static void
341 __update_max_tr(struct trace_array *tr, struct task_struct *tsk, int cpu)
342 {
343         struct trace_array_cpu *data = tr->data[cpu];
344
345         max_tr.cpu = cpu;
346         max_tr.time_start = data->preempt_timestamp;
347
348         data = max_tr.data[cpu];
349         data->saved_latency = tracing_max_latency;
350
351         memcpy(data->comm, tsk->comm, TASK_COMM_LEN);
352         data->pid = tsk->pid;
353         data->uid = task_uid(tsk);
354         data->nice = tsk->static_prio - 20 - MAX_RT_PRIO;
355         data->policy = tsk->policy;
356         data->rt_priority = tsk->rt_priority;
357
358         /* record this tasks comm */
359         tracing_record_cmdline(tsk);
360 }
361
362 ssize_t trace_seq_to_user(struct trace_seq *s, char __user *ubuf, size_t cnt)
363 {
364         int len;
365         int ret;
366
367         if (!cnt)
368                 return 0;
369
370         if (s->len <= s->readpos)
371                 return -EBUSY;
372
373         len = s->len - s->readpos;
374         if (cnt > len)
375                 cnt = len;
376         ret = copy_to_user(ubuf, s->buffer + s->readpos, cnt);
377         if (ret == cnt)
378                 return -EFAULT;
379
380         cnt -= ret;
381
382         s->readpos += cnt;
383         return cnt;
384 }
385
386 static ssize_t trace_seq_to_buffer(struct trace_seq *s, void *buf, size_t cnt)
387 {
388         int len;
389         void *ret;
390
391         if (s->len <= s->readpos)
392                 return -EBUSY;
393
394         len = s->len - s->readpos;
395         if (cnt > len)
396                 cnt = len;
397         ret = memcpy(buf, s->buffer + s->readpos, cnt);
398         if (!ret)
399                 return -EFAULT;
400
401         s->readpos += cnt;
402         return cnt;
403 }
404
405 static void
406 trace_print_seq(struct seq_file *m, struct trace_seq *s)
407 {
408         int len = s->len >= PAGE_SIZE ? PAGE_SIZE - 1 : s->len;
409
410         s->buffer[len] = 0;
411         seq_puts(m, s->buffer);
412
413         trace_seq_init(s);
414 }
415
416 /**
417  * update_max_tr - snapshot all trace buffers from global_trace to max_tr
418  * @tr: tracer
419  * @tsk: the task with the latency
420  * @cpu: The cpu that initiated the trace.
421  *
422  * Flip the buffers between the @tr and the max_tr and record information
423  * about which task was the cause of this latency.
424  */
425 void
426 update_max_tr(struct trace_array *tr, struct task_struct *tsk, int cpu)
427 {
428         struct ring_buffer *buf = tr->buffer;
429
430         WARN_ON_ONCE(!irqs_disabled());
431         __raw_spin_lock(&ftrace_max_lock);
432
433         tr->buffer = max_tr.buffer;
434         max_tr.buffer = buf;
435
436         ftrace_disable_cpu();
437         ring_buffer_reset(tr->buffer);
438         ftrace_enable_cpu();
439
440         __update_max_tr(tr, tsk, cpu);
441         __raw_spin_unlock(&ftrace_max_lock);
442 }
443
444 /**
445  * update_max_tr_single - only copy one trace over, and reset the rest
446  * @tr - tracer
447  * @tsk - task with the latency
448  * @cpu - the cpu of the buffer to copy.
449  *
450  * Flip the trace of a single CPU buffer between the @tr and the max_tr.
451  */
452 void
453 update_max_tr_single(struct trace_array *tr, struct task_struct *tsk, int cpu)
454 {
455         int ret;
456
457         WARN_ON_ONCE(!irqs_disabled());
458         __raw_spin_lock(&ftrace_max_lock);
459
460         ftrace_disable_cpu();
461
462         ring_buffer_reset(max_tr.buffer);
463         ret = ring_buffer_swap_cpu(max_tr.buffer, tr->buffer, cpu);
464
465         ftrace_enable_cpu();
466
467         WARN_ON_ONCE(ret && ret != -EAGAIN);
468
469         __update_max_tr(tr, tsk, cpu);
470         __raw_spin_unlock(&ftrace_max_lock);
471 }
472
473 /**
474  * register_tracer - register a tracer with the ftrace system.
475  * @type - the plugin for the tracer
476  *
477  * Register a new plugin tracer.
478  */
479 int register_tracer(struct tracer *type)
480 __releases(kernel_lock)
481 __acquires(kernel_lock)
482 {
483         struct tracer *t;
484         int len;
485         int ret = 0;
486
487         if (!type->name) {
488                 pr_info("Tracer must have a name\n");
489                 return -1;
490         }
491
492         /*
493          * When this gets called we hold the BKL which means that
494          * preemption is disabled. Various trace selftests however
495          * need to disable and enable preemption for successful tests.
496          * So we drop the BKL here and grab it after the tests again.
497          */
498         unlock_kernel();
499         mutex_lock(&trace_types_lock);
500
501         tracing_selftest_running = true;
502
503         for (t = trace_types; t; t = t->next) {
504                 if (strcmp(type->name, t->name) == 0) {
505                         /* already found */
506                         pr_info("Trace %s already registered\n",
507                                 type->name);
508                         ret = -1;
509                         goto out;
510                 }
511         }
512
513         if (!type->set_flag)
514                 type->set_flag = &dummy_set_flag;
515         if (!type->flags)
516                 type->flags = &dummy_tracer_flags;
517         else
518                 if (!type->flags->opts)
519                         type->flags->opts = dummy_tracer_opt;
520         if (!type->wait_pipe)
521                 type->wait_pipe = default_wait_pipe;
522
523
524 #ifdef CONFIG_FTRACE_STARTUP_TEST
525         if (type->selftest && !tracing_selftest_disabled) {
526                 struct tracer *saved_tracer = current_trace;
527                 struct trace_array *tr = &global_trace;
528                 int i;
529
530                 /*
531                  * Run a selftest on this tracer.
532                  * Here we reset the trace buffer, and set the current
533                  * tracer to be this tracer. The tracer can then run some
534                  * internal tracing to verify that everything is in order.
535                  * If we fail, we do not register this tracer.
536                  */
537                 for_each_tracing_cpu(i)
538                         tracing_reset(tr, i);
539
540                 current_trace = type;
541                 /* the test is responsible for initializing and enabling */
542                 pr_info("Testing tracer %s: ", type->name);
543                 ret = type->selftest(type, tr);
544                 /* the test is responsible for resetting too */
545                 current_trace = saved_tracer;
546                 if (ret) {
547                         printk(KERN_CONT "FAILED!\n");
548                         goto out;
549                 }
550                 /* Only reset on passing, to avoid touching corrupted buffers */
551                 for_each_tracing_cpu(i)
552                         tracing_reset(tr, i);
553
554                 printk(KERN_CONT "PASSED\n");
555         }
556 #endif
557
558         type->next = trace_types;
559         trace_types = type;
560         len = strlen(type->name);
561         if (len > max_tracer_type_len)
562                 max_tracer_type_len = len;
563
564  out:
565         tracing_selftest_running = false;
566         mutex_unlock(&trace_types_lock);
567
568         if (ret || !default_bootup_tracer)
569                 goto out_unlock;
570
571         if (strncmp(default_bootup_tracer, type->name, BOOTUP_TRACER_SIZE))
572                 goto out_unlock;
573
574         printk(KERN_INFO "Starting tracer '%s'\n", type->name);
575         /* Do we want this tracer to start on bootup? */
576         tracing_set_tracer(type->name);
577         default_bootup_tracer = NULL;
578         /* disable other selftests, since this will break it. */
579         tracing_selftest_disabled = 1;
580 #ifdef CONFIG_FTRACE_STARTUP_TEST
581         printk(KERN_INFO "Disabling FTRACE selftests due to running tracer '%s'\n",
582                type->name);
583 #endif
584
585  out_unlock:
586         lock_kernel();
587         return ret;
588 }
589
590 void unregister_tracer(struct tracer *type)
591 {
592         struct tracer **t;
593         int len;
594
595         mutex_lock(&trace_types_lock);
596         for (t = &trace_types; *t; t = &(*t)->next) {
597                 if (*t == type)
598                         goto found;
599         }
600         pr_info("Trace %s not registered\n", type->name);
601         goto out;
602
603  found:
604         *t = (*t)->next;
605
606         if (type == current_trace && tracer_enabled) {
607                 tracer_enabled = 0;
608                 tracing_stop();
609                 if (current_trace->stop)
610                         current_trace->stop(&global_trace);
611                 current_trace = &nop_trace;
612         }
613
614         if (strlen(type->name) != max_tracer_type_len)
615                 goto out;
616
617         max_tracer_type_len = 0;
618         for (t = &trace_types; *t; t = &(*t)->next) {
619                 len = strlen((*t)->name);
620                 if (len > max_tracer_type_len)
621                         max_tracer_type_len = len;
622         }
623  out:
624         mutex_unlock(&trace_types_lock);
625 }
626
627 void tracing_reset(struct trace_array *tr, int cpu)
628 {
629         ftrace_disable_cpu();
630         ring_buffer_reset_cpu(tr->buffer, cpu);
631         ftrace_enable_cpu();
632 }
633
634 void tracing_reset_online_cpus(struct trace_array *tr)
635 {
636         int cpu;
637
638         tr->time_start = ftrace_now(tr->cpu);
639
640         for_each_online_cpu(cpu)
641                 tracing_reset(tr, cpu);
642 }
643
644 #define SAVED_CMDLINES 128
645 #define NO_CMDLINE_MAP UINT_MAX
646 static unsigned map_pid_to_cmdline[PID_MAX_DEFAULT+1];
647 static unsigned map_cmdline_to_pid[SAVED_CMDLINES];
648 static char saved_cmdlines[SAVED_CMDLINES][TASK_COMM_LEN];
649 static int cmdline_idx;
650 static raw_spinlock_t trace_cmdline_lock = __RAW_SPIN_LOCK_UNLOCKED;
651
652 /* temporary disable recording */
653 static atomic_t trace_record_cmdline_disabled __read_mostly;
654
655 static void trace_init_cmdlines(void)
656 {
657         memset(&map_pid_to_cmdline, NO_CMDLINE_MAP, sizeof(map_pid_to_cmdline));
658         memset(&map_cmdline_to_pid, NO_CMDLINE_MAP, sizeof(map_cmdline_to_pid));
659         cmdline_idx = 0;
660 }
661
662 static int trace_stop_count;
663 static DEFINE_SPINLOCK(tracing_start_lock);
664
665 /**
666  * ftrace_off_permanent - disable all ftrace code permanently
667  *
668  * This should only be called when a serious anomally has
669  * been detected.  This will turn off the function tracing,
670  * ring buffers, and other tracing utilites. It takes no
671  * locks and can be called from any context.
672  */
673 void ftrace_off_permanent(void)
674 {
675         tracing_disabled = 1;
676         ftrace_stop();
677         tracing_off_permanent();
678 }
679
680 /**
681  * tracing_start - quick start of the tracer
682  *
683  * If tracing is enabled but was stopped by tracing_stop,
684  * this will start the tracer back up.
685  */
686 void tracing_start(void)
687 {
688         struct ring_buffer *buffer;
689         unsigned long flags;
690
691         if (tracing_disabled)
692                 return;
693
694         spin_lock_irqsave(&tracing_start_lock, flags);
695         if (--trace_stop_count) {
696                 if (trace_stop_count < 0) {
697                         /* Someone screwed up their debugging */
698                         WARN_ON_ONCE(1);
699                         trace_stop_count = 0;
700                 }
701                 goto out;
702         }
703
704
705         buffer = global_trace.buffer;
706         if (buffer)
707                 ring_buffer_record_enable(buffer);
708
709         buffer = max_tr.buffer;
710         if (buffer)
711                 ring_buffer_record_enable(buffer);
712
713         ftrace_start();
714  out:
715         spin_unlock_irqrestore(&tracing_start_lock, flags);
716 }
717
718 /**
719  * tracing_stop - quick stop of the tracer
720  *
721  * Light weight way to stop tracing. Use in conjunction with
722  * tracing_start.
723  */
724 void tracing_stop(void)
725 {
726         struct ring_buffer *buffer;
727         unsigned long flags;
728
729         ftrace_stop();
730         spin_lock_irqsave(&tracing_start_lock, flags);
731         if (trace_stop_count++)
732                 goto out;
733
734         buffer = global_trace.buffer;
735         if (buffer)
736                 ring_buffer_record_disable(buffer);
737
738         buffer = max_tr.buffer;
739         if (buffer)
740                 ring_buffer_record_disable(buffer);
741
742  out:
743         spin_unlock_irqrestore(&tracing_start_lock, flags);
744 }
745
746 void trace_stop_cmdline_recording(void);
747
748 static void trace_save_cmdline(struct task_struct *tsk)
749 {
750         unsigned pid, idx;
751
752         if (!tsk->pid || unlikely(tsk->pid > PID_MAX_DEFAULT))
753                 return;
754
755         /*
756          * It's not the end of the world if we don't get
757          * the lock, but we also don't want to spin
758          * nor do we want to disable interrupts,
759          * so if we miss here, then better luck next time.
760          */
761         if (!__raw_spin_trylock(&trace_cmdline_lock))
762                 return;
763
764         idx = map_pid_to_cmdline[tsk->pid];
765         if (idx == NO_CMDLINE_MAP) {
766                 idx = (cmdline_idx + 1) % SAVED_CMDLINES;
767
768                 /*
769                  * Check whether the cmdline buffer at idx has a pid
770                  * mapped. We are going to overwrite that entry so we
771                  * need to clear the map_pid_to_cmdline. Otherwise we
772                  * would read the new comm for the old pid.
773                  */
774                 pid = map_cmdline_to_pid[idx];
775                 if (pid != NO_CMDLINE_MAP)
776                         map_pid_to_cmdline[pid] = NO_CMDLINE_MAP;
777
778                 map_cmdline_to_pid[idx] = tsk->pid;
779                 map_pid_to_cmdline[tsk->pid] = idx;
780
781                 cmdline_idx = idx;
782         }
783
784         memcpy(&saved_cmdlines[idx], tsk->comm, TASK_COMM_LEN);
785
786         __raw_spin_unlock(&trace_cmdline_lock);
787 }
788
789 void trace_find_cmdline(int pid, char comm[])
790 {
791         unsigned map;
792
793         if (!pid) {
794                 strcpy(comm, "<idle>");
795                 return;
796         }
797
798         if (pid > PID_MAX_DEFAULT) {
799                 strcpy(comm, "<...>");
800                 return;
801         }
802
803         __raw_spin_lock(&trace_cmdline_lock);
804         map = map_pid_to_cmdline[pid];
805         if (map != NO_CMDLINE_MAP)
806                 strcpy(comm, saved_cmdlines[map]);
807         else
808                 strcpy(comm, "<...>");
809
810         __raw_spin_unlock(&trace_cmdline_lock);
811 }
812
813 void tracing_record_cmdline(struct task_struct *tsk)
814 {
815         if (atomic_read(&trace_record_cmdline_disabled) || !tracer_enabled ||
816             !tracing_is_on())
817                 return;
818
819         trace_save_cmdline(tsk);
820 }
821
822 void
823 tracing_generic_entry_update(struct trace_entry *entry, unsigned long flags,
824                              int pc)
825 {
826         struct task_struct *tsk = current;
827
828         entry->preempt_count            = pc & 0xff;
829         entry->pid                      = (tsk) ? tsk->pid : 0;
830         entry->tgid                     = (tsk) ? tsk->tgid : 0;
831         entry->flags =
832 #ifdef CONFIG_TRACE_IRQFLAGS_SUPPORT
833                 (irqs_disabled_flags(flags) ? TRACE_FLAG_IRQS_OFF : 0) |
834 #else
835                 TRACE_FLAG_IRQS_NOSUPPORT |
836 #endif
837                 ((pc & HARDIRQ_MASK) ? TRACE_FLAG_HARDIRQ : 0) |
838                 ((pc & SOFTIRQ_MASK) ? TRACE_FLAG_SOFTIRQ : 0) |
839                 (need_resched() ? TRACE_FLAG_NEED_RESCHED : 0);
840 }
841
842 struct ring_buffer_event *trace_buffer_lock_reserve(struct trace_array *tr,
843                                                     unsigned char type,
844                                                     unsigned long len,
845                                                     unsigned long flags, int pc)
846 {
847         struct ring_buffer_event *event;
848
849         event = ring_buffer_lock_reserve(tr->buffer, len);
850         if (event != NULL) {
851                 struct trace_entry *ent = ring_buffer_event_data(event);
852
853                 tracing_generic_entry_update(ent, flags, pc);
854                 ent->type = type;
855         }
856
857         return event;
858 }
859 static void ftrace_trace_stack(struct trace_array *tr,
860                                unsigned long flags, int skip, int pc);
861 static void ftrace_trace_userstack(struct trace_array *tr,
862                                    unsigned long flags, int pc);
863
864 static inline void __trace_buffer_unlock_commit(struct trace_array *tr,
865                                         struct ring_buffer_event *event,
866                                         unsigned long flags, int pc,
867                                         int wake)
868 {
869         ring_buffer_unlock_commit(tr->buffer, event);
870
871         ftrace_trace_stack(tr, flags, 6, pc);
872         ftrace_trace_userstack(tr, flags, pc);
873
874         if (wake)
875                 trace_wake_up();
876 }
877
878 void trace_buffer_unlock_commit(struct trace_array *tr,
879                                         struct ring_buffer_event *event,
880                                         unsigned long flags, int pc)
881 {
882         __trace_buffer_unlock_commit(tr, event, flags, pc, 1);
883 }
884
885 struct ring_buffer_event *
886 trace_current_buffer_lock_reserve(unsigned char type, unsigned long len,
887                                   unsigned long flags, int pc)
888 {
889         return trace_buffer_lock_reserve(&global_trace,
890                                          type, len, flags, pc);
891 }
892
893 void trace_current_buffer_unlock_commit(struct ring_buffer_event *event,
894                                         unsigned long flags, int pc)
895 {
896         return __trace_buffer_unlock_commit(&global_trace, event, flags, pc, 1);
897 }
898
899 void trace_nowake_buffer_unlock_commit(struct ring_buffer_event *event,
900                                         unsigned long flags, int pc)
901 {
902         return __trace_buffer_unlock_commit(&global_trace, event, flags, pc, 0);
903 }
904
905 void
906 trace_function(struct trace_array *tr,
907                unsigned long ip, unsigned long parent_ip, unsigned long flags,
908                int pc)
909 {
910         struct ring_buffer_event *event;
911         struct ftrace_entry *entry;
912
913         /* If we are reading the ring buffer, don't trace */
914         if (unlikely(local_read(&__get_cpu_var(ftrace_cpu_disabled))))
915                 return;
916
917         event = trace_buffer_lock_reserve(tr, TRACE_FN, sizeof(*entry),
918                                           flags, pc);
919         if (!event)
920                 return;
921         entry   = ring_buffer_event_data(event);
922         entry->ip                       = ip;
923         entry->parent_ip                = parent_ip;
924         ring_buffer_unlock_commit(tr->buffer, event);
925 }
926
927 #ifdef CONFIG_FUNCTION_GRAPH_TRACER
928 static int __trace_graph_entry(struct trace_array *tr,
929                                 struct ftrace_graph_ent *trace,
930                                 unsigned long flags,
931                                 int pc)
932 {
933         struct ring_buffer_event *event;
934         struct ftrace_graph_ent_entry *entry;
935
936         if (unlikely(local_read(&__get_cpu_var(ftrace_cpu_disabled))))
937                 return 0;
938
939         event = trace_buffer_lock_reserve(&global_trace, TRACE_GRAPH_ENT,
940                                           sizeof(*entry), flags, pc);
941         if (!event)
942                 return 0;
943         entry   = ring_buffer_event_data(event);
944         entry->graph_ent                        = *trace;
945         ring_buffer_unlock_commit(global_trace.buffer, event);
946
947         return 1;
948 }
949
950 static void __trace_graph_return(struct trace_array *tr,
951                                 struct ftrace_graph_ret *trace,
952                                 unsigned long flags,
953                                 int pc)
954 {
955         struct ring_buffer_event *event;
956         struct ftrace_graph_ret_entry *entry;
957
958         if (unlikely(local_read(&__get_cpu_var(ftrace_cpu_disabled))))
959                 return;
960
961         event = trace_buffer_lock_reserve(&global_trace, TRACE_GRAPH_RET,
962                                           sizeof(*entry), flags, pc);
963         if (!event)
964                 return;
965         entry   = ring_buffer_event_data(event);
966         entry->ret                              = *trace;
967         ring_buffer_unlock_commit(global_trace.buffer, event);
968 }
969 #endif
970
971 void
972 ftrace(struct trace_array *tr, struct trace_array_cpu *data,
973        unsigned long ip, unsigned long parent_ip, unsigned long flags,
974        int pc)
975 {
976         if (likely(!atomic_read(&data->disabled)))
977                 trace_function(tr, ip, parent_ip, flags, pc);
978 }
979
980 static void __ftrace_trace_stack(struct trace_array *tr,
981                                  unsigned long flags,
982                                  int skip, int pc)
983 {
984 #ifdef CONFIG_STACKTRACE
985         struct ring_buffer_event *event;
986         struct stack_entry *entry;
987         struct stack_trace trace;
988
989         event = trace_buffer_lock_reserve(tr, TRACE_STACK,
990                                           sizeof(*entry), flags, pc);
991         if (!event)
992                 return;
993         entry   = ring_buffer_event_data(event);
994         memset(&entry->caller, 0, sizeof(entry->caller));
995
996         trace.nr_entries        = 0;
997         trace.max_entries       = FTRACE_STACK_ENTRIES;
998         trace.skip              = skip;
999         trace.entries           = entry->caller;
1000
1001         save_stack_trace(&trace);
1002         ring_buffer_unlock_commit(tr->buffer, event);
1003 #endif
1004 }
1005
1006 static void ftrace_trace_stack(struct trace_array *tr,
1007                                unsigned long flags,
1008                                int skip, int pc)
1009 {
1010         if (!(trace_flags & TRACE_ITER_STACKTRACE))
1011                 return;
1012
1013         __ftrace_trace_stack(tr, flags, skip, pc);
1014 }
1015
1016 void __trace_stack(struct trace_array *tr,
1017                    unsigned long flags,
1018                    int skip, int pc)
1019 {
1020         __ftrace_trace_stack(tr, flags, skip, pc);
1021 }
1022
1023 static void ftrace_trace_userstack(struct trace_array *tr,
1024                                    unsigned long flags, int pc)
1025 {
1026 #ifdef CONFIG_STACKTRACE
1027         struct ring_buffer_event *event;
1028         struct userstack_entry *entry;
1029         struct stack_trace trace;
1030
1031         if (!(trace_flags & TRACE_ITER_USERSTACKTRACE))
1032                 return;
1033
1034         event = trace_buffer_lock_reserve(tr, TRACE_USER_STACK,
1035                                           sizeof(*entry), flags, pc);
1036         if (!event)
1037                 return;
1038         entry   = ring_buffer_event_data(event);
1039
1040         memset(&entry->caller, 0, sizeof(entry->caller));
1041
1042         trace.nr_entries        = 0;
1043         trace.max_entries       = FTRACE_STACK_ENTRIES;
1044         trace.skip              = 0;
1045         trace.entries           = entry->caller;
1046
1047         save_stack_trace_user(&trace);
1048         ring_buffer_unlock_commit(tr->buffer, event);
1049 #endif
1050 }
1051
1052 #ifdef UNUSED
1053 static void __trace_userstack(struct trace_array *tr, unsigned long flags)
1054 {
1055         ftrace_trace_userstack(tr, flags, preempt_count());
1056 }
1057 #endif /* UNUSED */
1058
1059 static void
1060 ftrace_trace_special(void *__tr,
1061                      unsigned long arg1, unsigned long arg2, unsigned long arg3,
1062                      int pc)
1063 {
1064         struct ring_buffer_event *event;
1065         struct trace_array *tr = __tr;
1066         struct special_entry *entry;
1067
1068         event = trace_buffer_lock_reserve(tr, TRACE_SPECIAL,
1069                                           sizeof(*entry), 0, pc);
1070         if (!event)
1071                 return;
1072         entry   = ring_buffer_event_data(event);
1073         entry->arg1                     = arg1;
1074         entry->arg2                     = arg2;
1075         entry->arg3                     = arg3;
1076         trace_buffer_unlock_commit(tr, event, 0, pc);
1077 }
1078
1079 void
1080 __trace_special(void *__tr, void *__data,
1081                 unsigned long arg1, unsigned long arg2, unsigned long arg3)
1082 {
1083         ftrace_trace_special(__tr, arg1, arg2, arg3, preempt_count());
1084 }
1085
1086 void
1087 tracing_sched_switch_trace(struct trace_array *tr,
1088                            struct task_struct *prev,
1089                            struct task_struct *next,
1090                            unsigned long flags, int pc)
1091 {
1092         struct ring_buffer_event *event;
1093         struct ctx_switch_entry *entry;
1094
1095         event = trace_buffer_lock_reserve(tr, TRACE_CTX,
1096                                           sizeof(*entry), flags, pc);
1097         if (!event)
1098                 return;
1099         entry   = ring_buffer_event_data(event);
1100         entry->prev_pid                 = prev->pid;
1101         entry->prev_prio                = prev->prio;
1102         entry->prev_state               = prev->state;
1103         entry->next_pid                 = next->pid;
1104         entry->next_prio                = next->prio;
1105         entry->next_state               = next->state;
1106         entry->next_cpu = task_cpu(next);
1107         trace_buffer_unlock_commit(tr, event, flags, pc);
1108 }
1109
1110 void
1111 tracing_sched_wakeup_trace(struct trace_array *tr,
1112                            struct task_struct *wakee,
1113                            struct task_struct *curr,
1114                            unsigned long flags, int pc)
1115 {
1116         struct ring_buffer_event *event;
1117         struct ctx_switch_entry *entry;
1118
1119         event = trace_buffer_lock_reserve(tr, TRACE_WAKE,
1120                                           sizeof(*entry), flags, pc);
1121         if (!event)
1122                 return;
1123         entry   = ring_buffer_event_data(event);
1124         entry->prev_pid                 = curr->pid;
1125         entry->prev_prio                = curr->prio;
1126         entry->prev_state               = curr->state;
1127         entry->next_pid                 = wakee->pid;
1128         entry->next_prio                = wakee->prio;
1129         entry->next_state               = wakee->state;
1130         entry->next_cpu                 = task_cpu(wakee);
1131
1132         ring_buffer_unlock_commit(tr->buffer, event);
1133         ftrace_trace_stack(tr, flags, 6, pc);
1134         ftrace_trace_userstack(tr, flags, pc);
1135 }
1136
1137 void
1138 ftrace_special(unsigned long arg1, unsigned long arg2, unsigned long arg3)
1139 {
1140         struct trace_array *tr = &global_trace;
1141         struct trace_array_cpu *data;
1142         unsigned long flags;
1143         int cpu;
1144         int pc;
1145
1146         if (tracing_disabled)
1147                 return;
1148
1149         pc = preempt_count();
1150         local_irq_save(flags);
1151         cpu = raw_smp_processor_id();
1152         data = tr->data[cpu];
1153
1154         if (likely(atomic_inc_return(&data->disabled) == 1))
1155                 ftrace_trace_special(tr, arg1, arg2, arg3, pc);
1156
1157         atomic_dec(&data->disabled);
1158         local_irq_restore(flags);
1159 }
1160
1161 #ifdef CONFIG_FUNCTION_GRAPH_TRACER
1162 int trace_graph_entry(struct ftrace_graph_ent *trace)
1163 {
1164         struct trace_array *tr = &global_trace;
1165         struct trace_array_cpu *data;
1166         unsigned long flags;
1167         long disabled;
1168         int ret;
1169         int cpu;
1170         int pc;
1171
1172         if (!ftrace_trace_task(current))
1173                 return 0;
1174
1175         if (!ftrace_graph_addr(trace->func))
1176                 return 0;
1177
1178         local_irq_save(flags);
1179         cpu = raw_smp_processor_id();
1180         data = tr->data[cpu];
1181         disabled = atomic_inc_return(&data->disabled);
1182         if (likely(disabled == 1)) {
1183                 pc = preempt_count();
1184                 ret = __trace_graph_entry(tr, trace, flags, pc);
1185         } else {
1186                 ret = 0;
1187         }
1188         /* Only do the atomic if it is not already set */
1189         if (!test_tsk_trace_graph(current))
1190                 set_tsk_trace_graph(current);
1191
1192         atomic_dec(&data->disabled);
1193         local_irq_restore(flags);
1194
1195         return ret;
1196 }
1197
1198 void trace_graph_return(struct ftrace_graph_ret *trace)
1199 {
1200         struct trace_array *tr = &global_trace;
1201         struct trace_array_cpu *data;
1202         unsigned long flags;
1203         long disabled;
1204         int cpu;
1205         int pc;
1206
1207         local_irq_save(flags);
1208         cpu = raw_smp_processor_id();
1209         data = tr->data[cpu];
1210         disabled = atomic_inc_return(&data->disabled);
1211         if (likely(disabled == 1)) {
1212                 pc = preempt_count();
1213                 __trace_graph_return(tr, trace, flags, pc);
1214         }
1215         if (!trace->depth)
1216                 clear_tsk_trace_graph(current);
1217         atomic_dec(&data->disabled);
1218         local_irq_restore(flags);
1219 }
1220 #endif /* CONFIG_FUNCTION_GRAPH_TRACER */
1221
1222
1223 /**
1224  * trace_vbprintk - write binary msg to tracing buffer
1225  *
1226  */
1227 int trace_vbprintk(unsigned long ip, const char *fmt, va_list args)
1228 {
1229         static raw_spinlock_t trace_buf_lock =
1230                 (raw_spinlock_t)__RAW_SPIN_LOCK_UNLOCKED;
1231         static u32 trace_buf[TRACE_BUF_SIZE];
1232
1233         struct ring_buffer_event *event;
1234         struct trace_array *tr = &global_trace;
1235         struct trace_array_cpu *data;
1236         struct bprint_entry *entry;
1237         unsigned long flags;
1238         int resched;
1239         int cpu, len = 0, size, pc;
1240
1241         if (unlikely(tracing_selftest_running || tracing_disabled))
1242                 return 0;
1243
1244         /* Don't pollute graph traces with trace_vprintk internals */
1245         pause_graph_tracing();
1246
1247         pc = preempt_count();
1248         resched = ftrace_preempt_disable();
1249         cpu = raw_smp_processor_id();
1250         data = tr->data[cpu];
1251
1252         if (unlikely(atomic_read(&data->disabled)))
1253                 goto out;
1254
1255         /* Lockdep uses trace_printk for lock tracing */
1256         local_irq_save(flags);
1257         __raw_spin_lock(&trace_buf_lock);
1258         len = vbin_printf(trace_buf, TRACE_BUF_SIZE, fmt, args);
1259
1260         if (len > TRACE_BUF_SIZE || len < 0)
1261                 goto out_unlock;
1262
1263         size = sizeof(*entry) + sizeof(u32) * len;
1264         event = trace_buffer_lock_reserve(tr, TRACE_BPRINT, size, flags, pc);
1265         if (!event)
1266                 goto out_unlock;
1267         entry = ring_buffer_event_data(event);
1268         entry->ip                       = ip;
1269         entry->fmt                      = fmt;
1270
1271         memcpy(entry->buf, trace_buf, sizeof(u32) * len);
1272         ring_buffer_unlock_commit(tr->buffer, event);
1273
1274 out_unlock:
1275         __raw_spin_unlock(&trace_buf_lock);
1276         local_irq_restore(flags);
1277
1278 out:
1279         ftrace_preempt_enable(resched);
1280         unpause_graph_tracing();
1281
1282         return len;
1283 }
1284 EXPORT_SYMBOL_GPL(trace_vbprintk);
1285
1286 int trace_vprintk(unsigned long ip, const char *fmt, va_list args)
1287 {
1288         static raw_spinlock_t trace_buf_lock = __RAW_SPIN_LOCK_UNLOCKED;
1289         static char trace_buf[TRACE_BUF_SIZE];
1290
1291         struct ring_buffer_event *event;
1292         struct trace_array *tr = &global_trace;
1293         struct trace_array_cpu *data;
1294         int cpu, len = 0, size, pc;
1295         struct print_entry *entry;
1296         unsigned long irq_flags;
1297
1298         if (tracing_disabled || tracing_selftest_running)
1299                 return 0;
1300
1301         pc = preempt_count();
1302         preempt_disable_notrace();
1303         cpu = raw_smp_processor_id();
1304         data = tr->data[cpu];
1305
1306         if (unlikely(atomic_read(&data->disabled)))
1307                 goto out;
1308
1309         pause_graph_tracing();
1310         raw_local_irq_save(irq_flags);
1311         __raw_spin_lock(&trace_buf_lock);
1312         len = vsnprintf(trace_buf, TRACE_BUF_SIZE, fmt, args);
1313
1314         len = min(len, TRACE_BUF_SIZE-1);
1315         trace_buf[len] = 0;
1316
1317         size = sizeof(*entry) + len + 1;
1318         event = trace_buffer_lock_reserve(tr, TRACE_PRINT, size, irq_flags, pc);
1319         if (!event)
1320                 goto out_unlock;
1321         entry = ring_buffer_event_data(event);
1322         entry->ip                       = ip;
1323
1324         memcpy(&entry->buf, trace_buf, len);
1325         entry->buf[len] = 0;
1326         ring_buffer_unlock_commit(tr->buffer, event);
1327
1328  out_unlock:
1329         __raw_spin_unlock(&trace_buf_lock);
1330         raw_local_irq_restore(irq_flags);
1331         unpause_graph_tracing();
1332  out:
1333         preempt_enable_notrace();
1334
1335         return len;
1336 }
1337 EXPORT_SYMBOL_GPL(trace_vprintk);
1338
1339 enum trace_file_type {
1340         TRACE_FILE_LAT_FMT      = 1,
1341         TRACE_FILE_ANNOTATE     = 2,
1342 };
1343
1344 static void trace_iterator_increment(struct trace_iterator *iter)
1345 {
1346         /* Don't allow ftrace to trace into the ring buffers */
1347         ftrace_disable_cpu();
1348
1349         iter->idx++;
1350         if (iter->buffer_iter[iter->cpu])
1351                 ring_buffer_read(iter->buffer_iter[iter->cpu], NULL);
1352
1353         ftrace_enable_cpu();
1354 }
1355
1356 static struct trace_entry *
1357 peek_next_entry(struct trace_iterator *iter, int cpu, u64 *ts)
1358 {
1359         struct ring_buffer_event *event;
1360         struct ring_buffer_iter *buf_iter = iter->buffer_iter[cpu];
1361
1362         /* Don't allow ftrace to trace into the ring buffers */
1363         ftrace_disable_cpu();
1364
1365         if (buf_iter)
1366                 event = ring_buffer_iter_peek(buf_iter, ts);
1367         else
1368                 event = ring_buffer_peek(iter->tr->buffer, cpu, ts);
1369
1370         ftrace_enable_cpu();
1371
1372         return event ? ring_buffer_event_data(event) : NULL;
1373 }
1374
1375 static struct trace_entry *
1376 __find_next_entry(struct trace_iterator *iter, int *ent_cpu, u64 *ent_ts)
1377 {
1378         struct ring_buffer *buffer = iter->tr->buffer;
1379         struct trace_entry *ent, *next = NULL;
1380         int cpu_file = iter->cpu_file;
1381         u64 next_ts = 0, ts;
1382         int next_cpu = -1;
1383         int cpu;
1384
1385         /*
1386          * If we are in a per_cpu trace file, don't bother by iterating over
1387          * all cpu and peek directly.
1388          */
1389         if (cpu_file > TRACE_PIPE_ALL_CPU) {
1390                 if (ring_buffer_empty_cpu(buffer, cpu_file))
1391                         return NULL;
1392                 ent = peek_next_entry(iter, cpu_file, ent_ts);
1393                 if (ent_cpu)
1394                         *ent_cpu = cpu_file;
1395
1396                 return ent;
1397         }
1398
1399         for_each_tracing_cpu(cpu) {
1400
1401                 if (ring_buffer_empty_cpu(buffer, cpu))
1402                         continue;
1403
1404                 ent = peek_next_entry(iter, cpu, &ts);
1405
1406                 /*
1407                  * Pick the entry with the smallest timestamp:
1408                  */
1409                 if (ent && (!next || ts < next_ts)) {
1410                         next = ent;
1411                         next_cpu = cpu;
1412                         next_ts = ts;
1413                 }
1414         }
1415
1416         if (ent_cpu)
1417                 *ent_cpu = next_cpu;
1418
1419         if (ent_ts)
1420                 *ent_ts = next_ts;
1421
1422         return next;
1423 }
1424
1425 /* Find the next real entry, without updating the iterator itself */
1426 struct trace_entry *trace_find_next_entry(struct trace_iterator *iter,
1427                                           int *ent_cpu, u64 *ent_ts)
1428 {
1429         return __find_next_entry(iter, ent_cpu, ent_ts);
1430 }
1431
1432 /* Find the next real entry, and increment the iterator to the next entry */
1433 static void *find_next_entry_inc(struct trace_iterator *iter)
1434 {
1435         iter->ent = __find_next_entry(iter, &iter->cpu, &iter->ts);
1436
1437         if (iter->ent)
1438                 trace_iterator_increment(iter);
1439
1440         return iter->ent ? iter : NULL;
1441 }
1442
1443 static void trace_consume(struct trace_iterator *iter)
1444 {
1445         /* Don't allow ftrace to trace into the ring buffers */
1446         ftrace_disable_cpu();
1447         ring_buffer_consume(iter->tr->buffer, iter->cpu, &iter->ts);
1448         ftrace_enable_cpu();
1449 }
1450
1451 static void *s_next(struct seq_file *m, void *v, loff_t *pos)
1452 {
1453         struct trace_iterator *iter = m->private;
1454         int i = (int)*pos;
1455         void *ent;
1456
1457         (*pos)++;
1458
1459         /* can't go backwards */
1460         if (iter->idx > i)
1461                 return NULL;
1462
1463         if (iter->idx < 0)
1464                 ent = find_next_entry_inc(iter);
1465         else
1466                 ent = iter;
1467
1468         while (ent && iter->idx < i)
1469                 ent = find_next_entry_inc(iter);
1470
1471         iter->pos = *pos;
1472
1473         return ent;
1474 }
1475
1476 /*
1477  * No necessary locking here. The worst thing which can
1478  * happen is loosing events consumed at the same time
1479  * by a trace_pipe reader.
1480  * Other than that, we don't risk to crash the ring buffer
1481  * because it serializes the readers.
1482  *
1483  * The current tracer is copied to avoid a global locking
1484  * all around.
1485  */
1486 static void *s_start(struct seq_file *m, loff_t *pos)
1487 {
1488         struct trace_iterator *iter = m->private;
1489         static struct tracer *old_tracer;
1490         int cpu_file = iter->cpu_file;
1491         void *p = NULL;
1492         loff_t l = 0;
1493         int cpu;
1494
1495         /* copy the tracer to avoid using a global lock all around */
1496         mutex_lock(&trace_types_lock);
1497         if (unlikely(old_tracer != current_trace && current_trace)) {
1498                 old_tracer = current_trace;
1499                 *iter->trace = *current_trace;
1500         }
1501         mutex_unlock(&trace_types_lock);
1502
1503         atomic_inc(&trace_record_cmdline_disabled);
1504
1505         if (*pos != iter->pos) {
1506                 iter->ent = NULL;
1507                 iter->cpu = 0;
1508                 iter->idx = -1;
1509
1510                 ftrace_disable_cpu();
1511
1512                 if (cpu_file == TRACE_PIPE_ALL_CPU) {
1513                         for_each_tracing_cpu(cpu)
1514                                 ring_buffer_iter_reset(iter->buffer_iter[cpu]);
1515                 } else
1516                         ring_buffer_iter_reset(iter->buffer_iter[cpu_file]);
1517
1518
1519                 ftrace_enable_cpu();
1520
1521                 for (p = iter; p && l < *pos; p = s_next(m, p, &l))
1522                         ;
1523
1524         } else {
1525                 l = *pos - 1;
1526                 p = s_next(m, p, &l);
1527         }
1528
1529         return p;
1530 }
1531
1532 static void s_stop(struct seq_file *m, void *p)
1533 {
1534         atomic_dec(&trace_record_cmdline_disabled);
1535 }
1536
1537 static void print_lat_help_header(struct seq_file *m)
1538 {
1539         seq_puts(m, "#                  _------=> CPU#            \n");
1540         seq_puts(m, "#                 / _-----=> irqs-off        \n");
1541         seq_puts(m, "#                | / _----=> need-resched    \n");
1542         seq_puts(m, "#                || / _---=> hardirq/softirq \n");
1543         seq_puts(m, "#                ||| / _--=> preempt-depth   \n");
1544         seq_puts(m, "#                |||| /                      \n");
1545         seq_puts(m, "#                |||||     delay             \n");
1546         seq_puts(m, "#  cmd     pid   ||||| time  |   caller      \n");
1547         seq_puts(m, "#     \\   /      |||||   \\   |   /           \n");
1548 }
1549
1550 static void print_func_help_header(struct seq_file *m)
1551 {
1552         seq_puts(m, "#           TASK-PID    CPU#    TIMESTAMP  FUNCTION\n");
1553         seq_puts(m, "#              | |       |          |         |\n");
1554 }
1555
1556
1557 static void
1558 print_trace_header(struct seq_file *m, struct trace_iterator *iter)
1559 {
1560         unsigned long sym_flags = (trace_flags & TRACE_ITER_SYM_MASK);
1561         struct trace_array *tr = iter->tr;
1562         struct trace_array_cpu *data = tr->data[tr->cpu];
1563         struct tracer *type = current_trace;
1564         unsigned long total;
1565         unsigned long entries;
1566         const char *name = "preemption";
1567
1568         if (type)
1569                 name = type->name;
1570
1571         entries = ring_buffer_entries(iter->tr->buffer);
1572         total = entries +
1573                 ring_buffer_overruns(iter->tr->buffer);
1574
1575         seq_printf(m, "# %s latency trace v1.1.5 on %s\n",
1576                    name, UTS_RELEASE);
1577         seq_puts(m, "# -----------------------------------"
1578                  "---------------------------------\n");
1579         seq_printf(m, "# latency: %lu us, #%lu/%lu, CPU#%d |"
1580                    " (M:%s VP:%d, KP:%d, SP:%d HP:%d",
1581                    nsecs_to_usecs(data->saved_latency),
1582                    entries,
1583                    total,
1584                    tr->cpu,
1585 #if defined(CONFIG_PREEMPT_NONE)
1586                    "server",
1587 #elif defined(CONFIG_PREEMPT_VOLUNTARY)
1588                    "desktop",
1589 #elif defined(CONFIG_PREEMPT)
1590                    "preempt",
1591 #else
1592                    "unknown",
1593 #endif
1594                    /* These are reserved for later use */
1595                    0, 0, 0, 0);
1596 #ifdef CONFIG_SMP
1597         seq_printf(m, " #P:%d)\n", num_online_cpus());
1598 #else
1599         seq_puts(m, ")\n");
1600 #endif
1601         seq_puts(m, "#    -----------------\n");
1602         seq_printf(m, "#    | task: %.16s-%d "
1603                    "(uid:%d nice:%ld policy:%ld rt_prio:%ld)\n",
1604                    data->comm, data->pid, data->uid, data->nice,
1605                    data->policy, data->rt_priority);
1606         seq_puts(m, "#    -----------------\n");
1607
1608         if (data->critical_start) {
1609                 seq_puts(m, "#  => started at: ");
1610                 seq_print_ip_sym(&iter->seq, data->critical_start, sym_flags);
1611                 trace_print_seq(m, &iter->seq);
1612                 seq_puts(m, "\n#  => ended at:   ");
1613                 seq_print_ip_sym(&iter->seq, data->critical_end, sym_flags);
1614                 trace_print_seq(m, &iter->seq);
1615                 seq_puts(m, "#\n");
1616         }
1617
1618         seq_puts(m, "#\n");
1619 }
1620
1621 static void test_cpu_buff_start(struct trace_iterator *iter)
1622 {
1623         struct trace_seq *s = &iter->seq;
1624
1625         if (!(trace_flags & TRACE_ITER_ANNOTATE))
1626                 return;
1627
1628         if (!(iter->iter_flags & TRACE_FILE_ANNOTATE))
1629                 return;
1630
1631         if (cpumask_test_cpu(iter->cpu, iter->started))
1632                 return;
1633
1634         cpumask_set_cpu(iter->cpu, iter->started);
1635
1636         /* Don't print started cpu buffer for the first entry of the trace */
1637         if (iter->idx > 1)
1638                 trace_seq_printf(s, "##### CPU %u buffer started ####\n",
1639                                 iter->cpu);
1640 }
1641
1642 static enum print_line_t print_trace_fmt(struct trace_iterator *iter)
1643 {
1644         struct trace_seq *s = &iter->seq;
1645         unsigned long sym_flags = (trace_flags & TRACE_ITER_SYM_MASK);
1646         struct trace_entry *entry;
1647         struct trace_event *event;
1648
1649         entry = iter->ent;
1650
1651         test_cpu_buff_start(iter);
1652
1653         event = ftrace_find_event(entry->type);
1654
1655         if (trace_flags & TRACE_ITER_CONTEXT_INFO) {
1656                 if (iter->iter_flags & TRACE_FILE_LAT_FMT) {
1657                         if (!trace_print_lat_context(iter))
1658                                 goto partial;
1659                 } else {
1660                         if (!trace_print_context(iter))
1661                                 goto partial;
1662                 }
1663         }
1664
1665         if (event)
1666                 return event->trace(iter, sym_flags);
1667
1668         if (!trace_seq_printf(s, "Unknown type %d\n", entry->type))
1669                 goto partial;
1670
1671         return TRACE_TYPE_HANDLED;
1672 partial:
1673         return TRACE_TYPE_PARTIAL_LINE;
1674 }
1675
1676 static enum print_line_t print_raw_fmt(struct trace_iterator *iter)
1677 {
1678         struct trace_seq *s = &iter->seq;
1679         struct trace_entry *entry;
1680         struct trace_event *event;
1681
1682         entry = iter->ent;
1683
1684         if (trace_flags & TRACE_ITER_CONTEXT_INFO) {
1685                 if (!trace_seq_printf(s, "%d %d %llu ",
1686                                       entry->pid, iter->cpu, iter->ts))
1687                         goto partial;
1688         }
1689
1690         event = ftrace_find_event(entry->type);
1691         if (event)
1692                 return event->raw(iter, 0);
1693
1694         if (!trace_seq_printf(s, "%d ?\n", entry->type))
1695                 goto partial;
1696
1697         return TRACE_TYPE_HANDLED;
1698 partial:
1699         return TRACE_TYPE_PARTIAL_LINE;
1700 }
1701
1702 static enum print_line_t print_hex_fmt(struct trace_iterator *iter)
1703 {
1704         struct trace_seq *s = &iter->seq;
1705         unsigned char newline = '\n';
1706         struct trace_entry *entry;
1707         struct trace_event *event;
1708
1709         entry = iter->ent;
1710
1711         if (trace_flags & TRACE_ITER_CONTEXT_INFO) {
1712                 SEQ_PUT_HEX_FIELD_RET(s, entry->pid);
1713                 SEQ_PUT_HEX_FIELD_RET(s, iter->cpu);
1714                 SEQ_PUT_HEX_FIELD_RET(s, iter->ts);
1715         }
1716
1717         event = ftrace_find_event(entry->type);
1718         if (event) {
1719                 enum print_line_t ret = event->hex(iter, 0);
1720                 if (ret != TRACE_TYPE_HANDLED)
1721                         return ret;
1722         }
1723
1724         SEQ_PUT_FIELD_RET(s, newline);
1725
1726         return TRACE_TYPE_HANDLED;
1727 }
1728
1729 static enum print_line_t print_bin_fmt(struct trace_iterator *iter)
1730 {
1731         struct trace_seq *s = &iter->seq;
1732         struct trace_entry *entry;
1733         struct trace_event *event;
1734
1735         entry = iter->ent;
1736
1737         if (trace_flags & TRACE_ITER_CONTEXT_INFO) {
1738                 SEQ_PUT_FIELD_RET(s, entry->pid);
1739                 SEQ_PUT_FIELD_RET(s, iter->cpu);
1740                 SEQ_PUT_FIELD_RET(s, iter->ts);
1741         }
1742
1743         event = ftrace_find_event(entry->type);
1744         return event ? event->binary(iter, 0) : TRACE_TYPE_HANDLED;
1745 }
1746
1747 static int trace_empty(struct trace_iterator *iter)
1748 {
1749         int cpu;
1750
1751         /* If we are looking at one CPU buffer, only check that one */
1752         if (iter->cpu_file != TRACE_PIPE_ALL_CPU) {
1753                 cpu = iter->cpu_file;
1754                 if (iter->buffer_iter[cpu]) {
1755                         if (!ring_buffer_iter_empty(iter->buffer_iter[cpu]))
1756                                 return 0;
1757                 } else {
1758                         if (!ring_buffer_empty_cpu(iter->tr->buffer, cpu))
1759                                 return 0;
1760                 }
1761                 return 1;
1762         }
1763
1764         for_each_tracing_cpu(cpu) {
1765                 if (iter->buffer_iter[cpu]) {
1766                         if (!ring_buffer_iter_empty(iter->buffer_iter[cpu]))
1767                                 return 0;
1768                 } else {
1769                         if (!ring_buffer_empty_cpu(iter->tr->buffer, cpu))
1770                                 return 0;
1771                 }
1772         }
1773
1774         return 1;
1775 }
1776
1777 static enum print_line_t print_trace_line(struct trace_iterator *iter)
1778 {
1779         enum print_line_t ret;
1780
1781         if (iter->trace && iter->trace->print_line) {
1782                 ret = iter->trace->print_line(iter);
1783                 if (ret != TRACE_TYPE_UNHANDLED)
1784                         return ret;
1785         }
1786
1787         if (iter->ent->type == TRACE_BPRINT &&
1788                         trace_flags & TRACE_ITER_PRINTK &&
1789                         trace_flags & TRACE_ITER_PRINTK_MSGONLY)
1790                 return trace_print_bprintk_msg_only(iter);
1791
1792         if (iter->ent->type == TRACE_PRINT &&
1793                         trace_flags & TRACE_ITER_PRINTK &&
1794                         trace_flags & TRACE_ITER_PRINTK_MSGONLY)
1795                 return trace_print_printk_msg_only(iter);
1796
1797         if (trace_flags & TRACE_ITER_BIN)
1798                 return print_bin_fmt(iter);
1799
1800         if (trace_flags & TRACE_ITER_HEX)
1801                 return print_hex_fmt(iter);
1802
1803         if (trace_flags & TRACE_ITER_RAW)
1804                 return print_raw_fmt(iter);
1805
1806         return print_trace_fmt(iter);
1807 }
1808
1809 static int s_show(struct seq_file *m, void *v)
1810 {
1811         struct trace_iterator *iter = v;
1812
1813         if (iter->ent == NULL) {
1814                 if (iter->tr) {
1815                         seq_printf(m, "# tracer: %s\n", iter->trace->name);
1816                         seq_puts(m, "#\n");
1817                 }
1818                 if (iter->trace && iter->trace->print_header)
1819                         iter->trace->print_header(m);
1820                 else if (iter->iter_flags & TRACE_FILE_LAT_FMT) {
1821                         /* print nothing if the buffers are empty */
1822                         if (trace_empty(iter))
1823                                 return 0;
1824                         print_trace_header(m, iter);
1825                         if (!(trace_flags & TRACE_ITER_VERBOSE))
1826                                 print_lat_help_header(m);
1827                 } else {
1828                         if (!(trace_flags & TRACE_ITER_VERBOSE))
1829                                 print_func_help_header(m);
1830                 }
1831         } else {
1832                 print_trace_line(iter);
1833                 trace_print_seq(m, &iter->seq);
1834         }
1835
1836         return 0;
1837 }
1838
1839 static struct seq_operations tracer_seq_ops = {
1840         .start          = s_start,
1841         .next           = s_next,
1842         .stop           = s_stop,
1843         .show           = s_show,
1844 };
1845
1846 static struct trace_iterator *
1847 __tracing_open(struct inode *inode, struct file *file)
1848 {
1849         long cpu_file = (long) inode->i_private;
1850         void *fail_ret = ERR_PTR(-ENOMEM);
1851         struct trace_iterator *iter;
1852         struct seq_file *m;
1853         int cpu, ret;
1854
1855         if (tracing_disabled)
1856                 return ERR_PTR(-ENODEV);
1857
1858         iter = kzalloc(sizeof(*iter), GFP_KERNEL);
1859         if (!iter)
1860                 return ERR_PTR(-ENOMEM);
1861
1862         /*
1863          * We make a copy of the current tracer to avoid concurrent
1864          * changes on it while we are reading.
1865          */
1866         mutex_lock(&trace_types_lock);
1867         iter->trace = kzalloc(sizeof(*iter->trace), GFP_KERNEL);
1868         if (!iter->trace)
1869                 goto fail;
1870
1871         if (current_trace)
1872                 *iter->trace = *current_trace;
1873
1874         if (!alloc_cpumask_var(&iter->started, GFP_KERNEL))
1875                 goto fail;
1876
1877         cpumask_clear(iter->started);
1878
1879         if (current_trace && current_trace->print_max)
1880                 iter->tr = &max_tr;
1881         else
1882                 iter->tr = &global_trace;
1883         iter->pos = -1;
1884         mutex_init(&iter->mutex);
1885         iter->cpu_file = cpu_file;
1886
1887         /* Notify the tracer early; before we stop tracing. */
1888         if (iter->trace && iter->trace->open)
1889                 iter->trace->open(iter);
1890
1891         /* Annotate start of buffers if we had overruns */
1892         if (ring_buffer_overruns(iter->tr->buffer))
1893                 iter->iter_flags |= TRACE_FILE_ANNOTATE;
1894
1895         if (iter->cpu_file == TRACE_PIPE_ALL_CPU) {
1896                 for_each_tracing_cpu(cpu) {
1897
1898                         iter->buffer_iter[cpu] =
1899                                 ring_buffer_read_start(iter->tr->buffer, cpu);
1900                 }
1901         } else {
1902                 cpu = iter->cpu_file;
1903                 iter->buffer_iter[cpu] =
1904                                 ring_buffer_read_start(iter->tr->buffer, cpu);
1905         }
1906
1907         /* TODO stop tracer */
1908         ret = seq_open(file, &tracer_seq_ops);
1909         if (ret < 0) {
1910                 fail_ret = ERR_PTR(ret);
1911                 goto fail_buffer;
1912         }
1913
1914         m = file->private_data;
1915         m->private = iter;
1916
1917         /* stop the trace while dumping */
1918         tracing_stop();
1919
1920         mutex_unlock(&trace_types_lock);
1921
1922         return iter;
1923
1924  fail_buffer:
1925         for_each_tracing_cpu(cpu) {
1926                 if (iter->buffer_iter[cpu])
1927                         ring_buffer_read_finish(iter->buffer_iter[cpu]);
1928         }
1929         free_cpumask_var(iter->started);
1930  fail:
1931         mutex_unlock(&trace_types_lock);
1932         kfree(iter->trace);
1933         kfree(iter);
1934
1935         return fail_ret;
1936 }
1937
1938 int tracing_open_generic(struct inode *inode, struct file *filp)
1939 {
1940         if (tracing_disabled)
1941                 return -ENODEV;
1942
1943         filp->private_data = inode->i_private;
1944         return 0;
1945 }
1946
1947 static int tracing_release(struct inode *inode, struct file *file)
1948 {
1949         struct seq_file *m = (struct seq_file *)file->private_data;
1950         struct trace_iterator *iter;
1951         int cpu;
1952
1953         if (!(file->f_mode & FMODE_READ))
1954                 return 0;
1955
1956         iter = m->private;
1957
1958         mutex_lock(&trace_types_lock);
1959         for_each_tracing_cpu(cpu) {
1960                 if (iter->buffer_iter[cpu])
1961                         ring_buffer_read_finish(iter->buffer_iter[cpu]);
1962         }
1963
1964         if (iter->trace && iter->trace->close)
1965                 iter->trace->close(iter);
1966
1967         /* reenable tracing if it was previously enabled */
1968         tracing_start();
1969         mutex_unlock(&trace_types_lock);
1970
1971         seq_release(inode, file);
1972         mutex_destroy(&iter->mutex);
1973         free_cpumask_var(iter->started);
1974         kfree(iter->trace);
1975         kfree(iter);
1976         return 0;
1977 }
1978
1979 static int tracing_open(struct inode *inode, struct file *file)
1980 {
1981         struct trace_iterator *iter;
1982         int ret = 0;
1983
1984         /* If this file was open for write, then erase contents */
1985         if ((file->f_mode & FMODE_WRITE) &&
1986             !(file->f_flags & O_APPEND)) {
1987                 long cpu = (long) inode->i_private;
1988
1989                 if (cpu == TRACE_PIPE_ALL_CPU)
1990                         tracing_reset_online_cpus(&global_trace);
1991                 else
1992                         tracing_reset(&global_trace, cpu);
1993         }
1994
1995         if (file->f_mode & FMODE_READ) {
1996                 iter = __tracing_open(inode, file);
1997                 if (IS_ERR(iter))
1998                         ret = PTR_ERR(iter);
1999                 else if (trace_flags & TRACE_ITER_LATENCY_FMT)
2000                         iter->iter_flags |= TRACE_FILE_LAT_FMT;
2001         }
2002         return ret;
2003 }
2004
2005 static void *
2006 t_next(struct seq_file *m, void *v, loff_t *pos)
2007 {
2008         struct tracer *t = m->private;
2009
2010         (*pos)++;
2011
2012         if (t)
2013                 t = t->next;
2014
2015         m->private = t;
2016
2017         return t;
2018 }
2019
2020 static void *t_start(struct seq_file *m, loff_t *pos)
2021 {
2022         struct tracer *t = m->private;
2023         loff_t l = 0;
2024
2025         mutex_lock(&trace_types_lock);
2026         for (; t && l < *pos; t = t_next(m, t, &l))
2027                 ;
2028
2029         return t;
2030 }
2031
2032 static void t_stop(struct seq_file *m, void *p)
2033 {
2034         mutex_unlock(&trace_types_lock);
2035 }
2036
2037 static int t_show(struct seq_file *m, void *v)
2038 {
2039         struct tracer *t = v;
2040
2041         if (!t)
2042                 return 0;
2043
2044         seq_printf(m, "%s", t->name);
2045         if (t->next)
2046                 seq_putc(m, ' ');
2047         else
2048                 seq_putc(m, '\n');
2049
2050         return 0;
2051 }
2052
2053 static struct seq_operations show_traces_seq_ops = {
2054         .start          = t_start,
2055         .next           = t_next,
2056         .stop           = t_stop,
2057         .show           = t_show,
2058 };
2059
2060 static int show_traces_open(struct inode *inode, struct file *file)
2061 {
2062         int ret;
2063
2064         if (tracing_disabled)
2065                 return -ENODEV;
2066
2067         ret = seq_open(file, &show_traces_seq_ops);
2068         if (!ret) {
2069                 struct seq_file *m = file->private_data;
2070                 m->private = trace_types;
2071         }
2072
2073         return ret;
2074 }
2075
2076 static ssize_t
2077 tracing_write_stub(struct file *filp, const char __user *ubuf,
2078                    size_t count, loff_t *ppos)
2079 {
2080         return count;
2081 }
2082
2083 static const struct file_operations tracing_fops = {
2084         .open           = tracing_open,
2085         .read           = seq_read,
2086         .write          = tracing_write_stub,
2087         .llseek         = seq_lseek,
2088         .release        = tracing_release,
2089 };
2090
2091 static const struct file_operations show_traces_fops = {
2092         .open           = show_traces_open,
2093         .read           = seq_read,
2094         .release        = seq_release,
2095 };
2096
2097 /*
2098  * Only trace on a CPU if the bitmask is set:
2099  */
2100 static cpumask_var_t tracing_cpumask;
2101
2102 /*
2103  * The tracer itself will not take this lock, but still we want
2104  * to provide a consistent cpumask to user-space:
2105  */
2106 static DEFINE_MUTEX(tracing_cpumask_update_lock);
2107
2108 /*
2109  * Temporary storage for the character representation of the
2110  * CPU bitmask (and one more byte for the newline):
2111  */
2112 static char mask_str[NR_CPUS + 1];
2113
2114 static ssize_t
2115 tracing_cpumask_read(struct file *filp, char __user *ubuf,
2116                      size_t count, loff_t *ppos)
2117 {
2118         int len;
2119
2120         mutex_lock(&tracing_cpumask_update_lock);
2121
2122         len = cpumask_scnprintf(mask_str, count, tracing_cpumask);
2123         if (count - len < 2) {
2124                 count = -EINVAL;
2125                 goto out_err;
2126         }
2127         len += sprintf(mask_str + len, "\n");
2128         count = simple_read_from_buffer(ubuf, count, ppos, mask_str, NR_CPUS+1);
2129
2130 out_err:
2131         mutex_unlock(&tracing_cpumask_update_lock);
2132
2133         return count;
2134 }
2135
2136 static ssize_t
2137 tracing_cpumask_write(struct file *filp, const char __user *ubuf,
2138                       size_t count, loff_t *ppos)
2139 {
2140         int err, cpu;
2141         cpumask_var_t tracing_cpumask_new;
2142
2143         if (!alloc_cpumask_var(&tracing_cpumask_new, GFP_KERNEL))
2144                 return -ENOMEM;
2145
2146         mutex_lock(&tracing_cpumask_update_lock);
2147         err = cpumask_parse_user(ubuf, count, tracing_cpumask_new);
2148         if (err)
2149                 goto err_unlock;
2150
2151         local_irq_disable();
2152         __raw_spin_lock(&ftrace_max_lock);
2153         for_each_tracing_cpu(cpu) {
2154                 /*
2155                  * Increase/decrease the disabled counter if we are
2156                  * about to flip a bit in the cpumask:
2157                  */
2158                 if (cpumask_test_cpu(cpu, tracing_cpumask) &&
2159                                 !cpumask_test_cpu(cpu, tracing_cpumask_new)) {
2160                         atomic_inc(&global_trace.data[cpu]->disabled);
2161                 }
2162                 if (!cpumask_test_cpu(cpu, tracing_cpumask) &&
2163                                 cpumask_test_cpu(cpu, tracing_cpumask_new)) {
2164                         atomic_dec(&global_trace.data[cpu]->disabled);
2165                 }
2166         }
2167         __raw_spin_unlock(&ftrace_max_lock);
2168         local_irq_enable();
2169
2170         cpumask_copy(tracing_cpumask, tracing_cpumask_new);
2171
2172         mutex_unlock(&tracing_cpumask_update_lock);
2173         free_cpumask_var(tracing_cpumask_new);
2174
2175         return count;
2176
2177 err_unlock:
2178         mutex_unlock(&tracing_cpumask_update_lock);
2179         free_cpumask_var(tracing_cpumask);
2180
2181         return err;
2182 }
2183
2184 static const struct file_operations tracing_cpumask_fops = {
2185         .open           = tracing_open_generic,
2186         .read           = tracing_cpumask_read,
2187         .write          = tracing_cpumask_write,
2188 };
2189
2190 static ssize_t
2191 tracing_trace_options_read(struct file *filp, char __user *ubuf,
2192                        size_t cnt, loff_t *ppos)
2193 {
2194         struct tracer_opt *trace_opts;
2195         u32 tracer_flags;
2196         int len = 0;
2197         char *buf;
2198         int r = 0;
2199         int i;
2200
2201
2202         /* calculate max size */
2203         for (i = 0; trace_options[i]; i++) {
2204                 len += strlen(trace_options[i]);
2205                 len += 3; /* "no" and newline */
2206         }
2207
2208         mutex_lock(&trace_types_lock);
2209         tracer_flags = current_trace->flags->val;
2210         trace_opts = current_trace->flags->opts;
2211
2212         /*
2213          * Increase the size with names of options specific
2214          * of the current tracer.
2215          */
2216         for (i = 0; trace_opts[i].name; i++) {
2217                 len += strlen(trace_opts[i].name);
2218                 len += 3; /* "no" and newline */
2219         }
2220
2221         /* +2 for \n and \0 */
2222         buf = kmalloc(len + 2, GFP_KERNEL);
2223         if (!buf) {
2224                 mutex_unlock(&trace_types_lock);
2225                 return -ENOMEM;
2226         }
2227
2228         for (i = 0; trace_options[i]; i++) {
2229                 if (trace_flags & (1 << i))
2230                         r += sprintf(buf + r, "%s\n", trace_options[i]);
2231                 else
2232                         r += sprintf(buf + r, "no%s\n", trace_options[i]);
2233         }
2234
2235         for (i = 0; trace_opts[i].name; i++) {
2236                 if (tracer_flags & trace_opts[i].bit)
2237                         r += sprintf(buf + r, "%s\n",
2238                                 trace_opts[i].name);
2239                 else
2240                         r += sprintf(buf + r, "no%s\n",
2241                                 trace_opts[i].name);
2242         }
2243         mutex_unlock(&trace_types_lock);
2244
2245         WARN_ON(r >= len + 2);
2246
2247         r = simple_read_from_buffer(ubuf, cnt, ppos, buf, r);
2248
2249         kfree(buf);
2250         return r;
2251 }
2252
2253 /* Try to assign a tracer specific option */
2254 static int set_tracer_option(struct tracer *trace, char *cmp, int neg)
2255 {
2256         struct tracer_flags *trace_flags = trace->flags;
2257         struct tracer_opt *opts = NULL;
2258         int ret = 0, i = 0;
2259         int len;
2260
2261         for (i = 0; trace_flags->opts[i].name; i++) {
2262                 opts = &trace_flags->opts[i];
2263                 len = strlen(opts->name);
2264
2265                 if (strncmp(cmp, opts->name, len) == 0) {
2266                         ret = trace->set_flag(trace_flags->val,
2267                                 opts->bit, !neg);
2268                         break;
2269                 }
2270         }
2271         /* Not found */
2272         if (!trace_flags->opts[i].name)
2273                 return -EINVAL;
2274
2275         /* Refused to handle */
2276         if (ret)
2277                 return ret;
2278
2279         if (neg)
2280                 trace_flags->val &= ~opts->bit;
2281         else
2282                 trace_flags->val |= opts->bit;
2283
2284         return 0;
2285 }
2286
2287 static void set_tracer_flags(unsigned int mask, int enabled)
2288 {
2289         /* do nothing if flag is already set */
2290         if (!!(trace_flags & mask) == !!enabled)
2291                 return;
2292
2293         if (enabled)
2294                 trace_flags |= mask;
2295         else
2296                 trace_flags &= ~mask;
2297
2298         if (mask == TRACE_ITER_GLOBAL_CLK) {
2299                 u64 (*func)(void);
2300
2301                 if (enabled)
2302                         func = trace_clock_global;
2303                 else
2304                         func = trace_clock_local;
2305
2306                 mutex_lock(&trace_types_lock);
2307                 ring_buffer_set_clock(global_trace.buffer, func);
2308
2309                 if (max_tr.buffer)
2310                         ring_buffer_set_clock(max_tr.buffer, func);
2311                 mutex_unlock(&trace_types_lock);
2312         }
2313 }
2314
2315 static ssize_t
2316 tracing_trace_options_write(struct file *filp, const char __user *ubuf,
2317                         size_t cnt, loff_t *ppos)
2318 {
2319         char buf[64];
2320         char *cmp = buf;
2321         int neg = 0;
2322         int ret;
2323         int i;
2324
2325         if (cnt >= sizeof(buf))
2326                 return -EINVAL;
2327
2328         if (copy_from_user(&buf, ubuf, cnt))
2329                 return -EFAULT;
2330
2331         buf[cnt] = 0;
2332
2333         if (strncmp(buf, "no", 2) == 0) {
2334                 neg = 1;
2335                 cmp += 2;
2336         }
2337
2338         for (i = 0; trace_options[i]; i++) {
2339                 int len = strlen(trace_options[i]);
2340
2341                 if (strncmp(cmp, trace_options[i], len) == 0) {
2342                         set_tracer_flags(1 << i, !neg);
2343                         break;
2344                 }
2345         }
2346
2347         /* If no option could be set, test the specific tracer options */
2348         if (!trace_options[i]) {
2349                 mutex_lock(&trace_types_lock);
2350                 ret = set_tracer_option(current_trace, cmp, neg);
2351                 mutex_unlock(&trace_types_lock);
2352                 if (ret)
2353                         return ret;
2354         }
2355
2356         filp->f_pos += cnt;
2357
2358         return cnt;
2359 }
2360
2361 static const struct file_operations tracing_iter_fops = {
2362         .open           = tracing_open_generic,
2363         .read           = tracing_trace_options_read,
2364         .write          = tracing_trace_options_write,
2365 };
2366
2367 static const char readme_msg[] =
2368         "tracing mini-HOWTO:\n\n"
2369         "# mkdir /debug\n"
2370         "# mount -t debugfs nodev /debug\n\n"
2371         "# cat /debug/tracing/available_tracers\n"
2372         "wakeup preemptirqsoff preemptoff irqsoff function sched_switch nop\n\n"
2373         "# cat /debug/tracing/current_tracer\n"
2374         "nop\n"
2375         "# echo sched_switch > /debug/tracing/current_tracer\n"
2376         "# cat /debug/tracing/current_tracer\n"
2377         "sched_switch\n"
2378         "# cat /debug/tracing/trace_options\n"
2379         "noprint-parent nosym-offset nosym-addr noverbose\n"
2380         "# echo print-parent > /debug/tracing/trace_options\n"
2381         "# echo 1 > /debug/tracing/tracing_enabled\n"
2382         "# cat /debug/tracing/trace > /tmp/trace.txt\n"
2383         "echo 0 > /debug/tracing/tracing_enabled\n"
2384 ;
2385
2386 static ssize_t
2387 tracing_readme_read(struct file *filp, char __user *ubuf,
2388                        size_t cnt, loff_t *ppos)
2389 {
2390         return simple_read_from_buffer(ubuf, cnt, ppos,
2391                                         readme_msg, strlen(readme_msg));
2392 }
2393
2394 static const struct file_operations tracing_readme_fops = {
2395         .open           = tracing_open_generic,
2396         .read           = tracing_readme_read,
2397 };
2398
2399 static ssize_t
2400 tracing_ctrl_read(struct file *filp, char __user *ubuf,
2401                   size_t cnt, loff_t *ppos)
2402 {
2403         char buf[64];
2404         int r;
2405
2406         r = sprintf(buf, "%u\n", tracer_enabled);
2407         return simple_read_from_buffer(ubuf, cnt, ppos, buf, r);
2408 }
2409
2410 static ssize_t
2411 tracing_ctrl_write(struct file *filp, const char __user *ubuf,
2412                    size_t cnt, loff_t *ppos)
2413 {
2414         struct trace_array *tr = filp->private_data;
2415         char buf[64];
2416         unsigned long val;
2417         int ret;
2418
2419         if (cnt >= sizeof(buf))
2420                 return -EINVAL;
2421
2422         if (copy_from_user(&buf, ubuf, cnt))
2423                 return -EFAULT;
2424
2425         buf[cnt] = 0;
2426
2427         ret = strict_strtoul(buf, 10, &val);
2428         if (ret < 0)
2429                 return ret;
2430
2431         val = !!val;
2432
2433         mutex_lock(&trace_types_lock);
2434         if (tracer_enabled ^ val) {
2435                 if (val) {
2436                         tracer_enabled = 1;
2437                         if (current_trace->start)
2438                                 current_trace->start(tr);
2439                         tracing_start();
2440                 } else {
2441                         tracer_enabled = 0;
2442                         tracing_stop();
2443                         if (current_trace->stop)
2444                                 current_trace->stop(tr);
2445                 }
2446         }
2447         mutex_unlock(&trace_types_lock);
2448
2449         filp->f_pos += cnt;
2450
2451         return cnt;
2452 }
2453
2454 static ssize_t
2455 tracing_set_trace_read(struct file *filp, char __user *ubuf,
2456                        size_t cnt, loff_t *ppos)
2457 {
2458         char buf[max_tracer_type_len+2];
2459         int r;
2460
2461         mutex_lock(&trace_types_lock);
2462         if (current_trace)
2463                 r = sprintf(buf, "%s\n", current_trace->name);
2464         else
2465                 r = sprintf(buf, "\n");
2466         mutex_unlock(&trace_types_lock);
2467
2468         return simple_read_from_buffer(ubuf, cnt, ppos, buf, r);
2469 }
2470
2471 int tracer_init(struct tracer *t, struct trace_array *tr)
2472 {
2473         tracing_reset_online_cpus(tr);
2474         return t->init(tr);
2475 }
2476
2477 static int tracing_resize_ring_buffer(unsigned long size)
2478 {
2479         int ret;
2480
2481         /*
2482          * If kernel or user changes the size of the ring buffer
2483          * we use the size that was given, and we can forget about
2484          * expanding it later.
2485          */
2486         ring_buffer_expanded = 1;
2487
2488         ret = ring_buffer_resize(global_trace.buffer, size);
2489         if (ret < 0)
2490                 return ret;
2491
2492         ret = ring_buffer_resize(max_tr.buffer, size);
2493         if (ret < 0) {
2494                 int r;
2495
2496                 r = ring_buffer_resize(global_trace.buffer,
2497                                        global_trace.entries);
2498                 if (r < 0) {
2499                         /*
2500                          * AARGH! We are left with different
2501                          * size max buffer!!!!
2502                          * The max buffer is our "snapshot" buffer.
2503                          * When a tracer needs a snapshot (one of the
2504                          * latency tracers), it swaps the max buffer
2505                          * with the saved snap shot. We succeeded to
2506                          * update the size of the main buffer, but failed to
2507                          * update the size of the max buffer. But when we tried
2508                          * to reset the main buffer to the original size, we
2509                          * failed there too. This is very unlikely to
2510                          * happen, but if it does, warn and kill all
2511                          * tracing.
2512                          */
2513                         WARN_ON(1);
2514                         tracing_disabled = 1;
2515                 }
2516                 return ret;
2517         }
2518
2519         global_trace.entries = size;
2520
2521         return ret;
2522 }
2523
2524 /**
2525  * tracing_update_buffers - used by tracing facility to expand ring buffers
2526  *
2527  * To save on memory when the tracing is never used on a system with it
2528  * configured in. The ring buffers are set to a minimum size. But once
2529  * a user starts to use the tracing facility, then they need to grow
2530  * to their default size.
2531  *
2532  * This function is to be called when a tracer is about to be used.
2533  */
2534 int tracing_update_buffers(void)
2535 {
2536         int ret = 0;
2537
2538         mutex_lock(&trace_types_lock);
2539         if (!ring_buffer_expanded)
2540                 ret = tracing_resize_ring_buffer(trace_buf_size);
2541         mutex_unlock(&trace_types_lock);
2542
2543         return ret;
2544 }
2545
2546 struct trace_option_dentry;
2547
2548 static struct trace_option_dentry *
2549 create_trace_option_files(struct tracer *tracer);
2550
2551 static void
2552 destroy_trace_option_files(struct trace_option_dentry *topts);
2553
2554 static int tracing_set_tracer(const char *buf)
2555 {
2556         static struct trace_option_dentry *topts;
2557         struct trace_array *tr = &global_trace;
2558         struct tracer *t;
2559         int ret = 0;
2560
2561         mutex_lock(&trace_types_lock);
2562
2563         if (!ring_buffer_expanded) {
2564                 ret = tracing_resize_ring_buffer(trace_buf_size);
2565                 if (ret < 0)
2566                         goto out;
2567                 ret = 0;
2568         }
2569
2570         for (t = trace_types; t; t = t->next) {
2571                 if (strcmp(t->name, buf) == 0)
2572                         break;
2573         }
2574         if (!t) {
2575                 ret = -EINVAL;
2576                 goto out;
2577         }
2578         if (t == current_trace)
2579                 goto out;
2580
2581         trace_branch_disable();
2582         if (current_trace && current_trace->reset)
2583                 current_trace->reset(tr);
2584
2585         destroy_trace_option_files(topts);
2586
2587         current_trace = t;
2588
2589         topts = create_trace_option_files(current_trace);
2590
2591         if (t->init) {
2592                 ret = tracer_init(t, tr);
2593                 if (ret)
2594                         goto out;
2595         }
2596
2597         trace_branch_enable(tr);
2598  out:
2599         mutex_unlock(&trace_types_lock);
2600
2601         return ret;
2602 }
2603
2604 static ssize_t
2605 tracing_set_trace_write(struct file *filp, const char __user *ubuf,
2606                         size_t cnt, loff_t *ppos)
2607 {
2608         char buf[max_tracer_type_len+1];
2609         int i;
2610         size_t ret;
2611         int err;
2612
2613         ret = cnt;
2614
2615         if (cnt > max_tracer_type_len)
2616                 cnt = max_tracer_type_len;
2617
2618         if (copy_from_user(&buf, ubuf, cnt))
2619                 return -EFAULT;
2620
2621         buf[cnt] = 0;
2622
2623         /* strip ending whitespace. */
2624         for (i = cnt - 1; i > 0 && isspace(buf[i]); i--)
2625                 buf[i] = 0;
2626
2627         err = tracing_set_tracer(buf);
2628         if (err)
2629                 return err;
2630
2631         filp->f_pos += ret;
2632
2633         return ret;
2634 }
2635
2636 static ssize_t
2637 tracing_max_lat_read(struct file *filp, char __user *ubuf,
2638                      size_t cnt, loff_t *ppos)
2639 {
2640         unsigned long *ptr = filp->private_data;
2641         char buf[64];
2642         int r;
2643
2644         r = snprintf(buf, sizeof(buf), "%ld\n",
2645                      *ptr == (unsigned long)-1 ? -1 : nsecs_to_usecs(*ptr));
2646         if (r > sizeof(buf))
2647                 r = sizeof(buf);
2648         return simple_read_from_buffer(ubuf, cnt, ppos, buf, r);
2649 }
2650
2651 static ssize_t
2652 tracing_max_lat_write(struct file *filp, const char __user *ubuf,
2653                       size_t cnt, loff_t *ppos)
2654 {
2655         unsigned long *ptr = filp->private_data;
2656         char buf[64];
2657         unsigned long val;
2658         int ret;
2659
2660         if (cnt >= sizeof(buf))
2661                 return -EINVAL;
2662
2663         if (copy_from_user(&buf, ubuf, cnt))
2664                 return -EFAULT;
2665
2666         buf[cnt] = 0;
2667
2668         ret = strict_strtoul(buf, 10, &val);
2669         if (ret < 0)
2670                 return ret;
2671
2672         *ptr = val * 1000;
2673
2674         return cnt;
2675 }
2676
2677 static int tracing_open_pipe(struct inode *inode, struct file *filp)
2678 {
2679         long cpu_file = (long) inode->i_private;
2680         struct trace_iterator *iter;
2681         int ret = 0;
2682
2683         if (tracing_disabled)
2684                 return -ENODEV;
2685
2686         mutex_lock(&trace_types_lock);
2687
2688         /* We only allow one reader per cpu */
2689         if (cpu_file == TRACE_PIPE_ALL_CPU) {
2690                 if (!cpumask_empty(tracing_reader_cpumask)) {
2691                         ret = -EBUSY;
2692                         goto out;
2693                 }
2694                 cpumask_setall(tracing_reader_cpumask);
2695         } else {
2696                 if (!cpumask_test_cpu(cpu_file, tracing_reader_cpumask))
2697                         cpumask_set_cpu(cpu_file, tracing_reader_cpumask);
2698                 else {
2699                         ret = -EBUSY;
2700                         goto out;
2701                 }
2702         }
2703
2704         /* create a buffer to store the information to pass to userspace */
2705         iter = kzalloc(sizeof(*iter), GFP_KERNEL);
2706         if (!iter) {
2707                 ret = -ENOMEM;
2708                 goto out;
2709         }
2710
2711         /*
2712          * We make a copy of the current tracer to avoid concurrent
2713          * changes on it while we are reading.
2714          */
2715         iter->trace = kmalloc(sizeof(*iter->trace), GFP_KERNEL);
2716         if (!iter->trace) {
2717                 ret = -ENOMEM;
2718                 goto fail;
2719         }
2720         if (current_trace)
2721                 *iter->trace = *current_trace;
2722
2723         if (!alloc_cpumask_var(&iter->started, GFP_KERNEL)) {
2724                 ret = -ENOMEM;
2725                 goto fail;
2726         }
2727
2728         /* trace pipe does not show start of buffer */
2729         cpumask_setall(iter->started);
2730
2731         iter->cpu_file = cpu_file;
2732         iter->tr = &global_trace;
2733         mutex_init(&iter->mutex);
2734         filp->private_data = iter;
2735
2736         if (iter->trace->pipe_open)
2737                 iter->trace->pipe_open(iter);
2738
2739 out:
2740         mutex_unlock(&trace_types_lock);
2741         return ret;
2742
2743 fail:
2744         kfree(iter->trace);
2745         kfree(iter);
2746         mutex_unlock(&trace_types_lock);
2747         return ret;
2748 }
2749
2750 static int tracing_release_pipe(struct inode *inode, struct file *file)
2751 {
2752         struct trace_iterator *iter = file->private_data;
2753
2754         mutex_lock(&trace_types_lock);
2755
2756         if (iter->cpu_file == TRACE_PIPE_ALL_CPU)
2757                 cpumask_clear(tracing_reader_cpumask);
2758         else
2759                 cpumask_clear_cpu(iter->cpu_file, tracing_reader_cpumask);
2760
2761         mutex_unlock(&trace_types_lock);
2762
2763         free_cpumask_var(iter->started);
2764         mutex_destroy(&iter->mutex);
2765         kfree(iter->trace);
2766         kfree(iter);
2767
2768         return 0;
2769 }
2770
2771 static unsigned int
2772 tracing_poll_pipe(struct file *filp, poll_table *poll_table)
2773 {
2774         struct trace_iterator *iter = filp->private_data;
2775
2776         if (trace_flags & TRACE_ITER_BLOCK) {
2777                 /*
2778                  * Always select as readable when in blocking mode
2779                  */
2780                 return POLLIN | POLLRDNORM;
2781         } else {
2782                 if (!trace_empty(iter))
2783                         return POLLIN | POLLRDNORM;
2784                 poll_wait(filp, &trace_wait, poll_table);
2785                 if (!trace_empty(iter))
2786                         return POLLIN | POLLRDNORM;
2787
2788                 return 0;
2789         }
2790 }
2791
2792
2793 void default_wait_pipe(struct trace_iterator *iter)
2794 {
2795         DEFINE_WAIT(wait);
2796
2797         prepare_to_wait(&trace_wait, &wait, TASK_INTERRUPTIBLE);
2798
2799         if (trace_empty(iter))
2800                 schedule();
2801
2802         finish_wait(&trace_wait, &wait);
2803 }
2804
2805 /*
2806  * This is a make-shift waitqueue.
2807  * A tracer might use this callback on some rare cases:
2808  *
2809  *  1) the current tracer might hold the runqueue lock when it wakes up
2810  *     a reader, hence a deadlock (sched, function, and function graph tracers)
2811  *  2) the function tracers, trace all functions, we don't want
2812  *     the overhead of calling wake_up and friends
2813  *     (and tracing them too)
2814  *
2815  *     Anyway, this is really very primitive wakeup.
2816  */
2817 void poll_wait_pipe(struct trace_iterator *iter)
2818 {
2819         set_current_state(TASK_INTERRUPTIBLE);
2820         /* sleep for 100 msecs, and try again. */
2821         schedule_timeout(HZ / 10);
2822 }
2823
2824 /* Must be called with trace_types_lock mutex held. */
2825 static int tracing_wait_pipe(struct file *filp)
2826 {
2827         struct trace_iterator *iter = filp->private_data;
2828
2829         while (trace_empty(iter)) {
2830
2831                 if ((filp->f_flags & O_NONBLOCK)) {
2832                         return -EAGAIN;
2833                 }
2834
2835                 mutex_unlock(&iter->mutex);
2836
2837                 iter->trace->wait_pipe(iter);
2838
2839                 mutex_lock(&iter->mutex);
2840
2841                 if (signal_pending(current))
2842                         return -EINTR;
2843
2844                 /*
2845                  * We block until we read something and tracing is disabled.
2846                  * We still block if tracing is disabled, but we have never
2847                  * read anything. This allows a user to cat this file, and
2848                  * then enable tracing. But after we have read something,
2849                  * we give an EOF when tracing is again disabled.
2850                  *
2851                  * iter->pos will be 0 if we haven't read anything.
2852                  */
2853                 if (!tracer_enabled && iter->pos)
2854                         break;
2855         }
2856
2857         return 1;
2858 }
2859
2860 /*
2861  * Consumer reader.
2862  */
2863 static ssize_t
2864 tracing_read_pipe(struct file *filp, char __user *ubuf,
2865                   size_t cnt, loff_t *ppos)
2866 {
2867         struct trace_iterator *iter = filp->private_data;
2868         static struct tracer *old_tracer;
2869         ssize_t sret;
2870
2871         /* return any leftover data */
2872         sret = trace_seq_to_user(&iter->seq, ubuf, cnt);
2873         if (sret != -EBUSY)
2874                 return sret;
2875
2876         trace_seq_init(&iter->seq);
2877
2878         /* copy the tracer to avoid using a global lock all around */
2879         mutex_lock(&trace_types_lock);
2880         if (unlikely(old_tracer != current_trace && current_trace)) {
2881                 old_tracer = current_trace;
2882                 *iter->trace = *current_trace;
2883         }
2884         mutex_unlock(&trace_types_lock);
2885
2886         /*
2887          * Avoid more than one consumer on a single file descriptor
2888          * This is just a matter of traces coherency, the ring buffer itself
2889          * is protected.
2890          */
2891         mutex_lock(&iter->mutex);
2892         if (iter->trace->read) {
2893                 sret = iter->trace->read(iter, filp, ubuf, cnt, ppos);
2894                 if (sret)
2895                         goto out;
2896         }
2897
2898 waitagain:
2899         sret = tracing_wait_pipe(filp);
2900         if (sret <= 0)
2901                 goto out;
2902
2903         /* stop when tracing is finished */
2904         if (trace_empty(iter)) {
2905                 sret = 0;
2906                 goto out;
2907         }
2908
2909         if (cnt >= PAGE_SIZE)
2910                 cnt = PAGE_SIZE - 1;
2911
2912         /* reset all but tr, trace, and overruns */
2913         memset(&iter->seq, 0,
2914                sizeof(struct trace_iterator) -
2915                offsetof(struct trace_iterator, seq));
2916         iter->pos = -1;
2917
2918         while (find_next_entry_inc(iter) != NULL) {
2919                 enum print_line_t ret;
2920                 int len = iter->seq.len;
2921
2922                 ret = print_trace_line(iter);
2923                 if (ret == TRACE_TYPE_PARTIAL_LINE) {
2924                         /* don't print partial lines */
2925                         iter->seq.len = len;
2926                         break;
2927                 }
2928                 if (ret != TRACE_TYPE_NO_CONSUME)
2929                         trace_consume(iter);
2930
2931                 if (iter->seq.len >= cnt)
2932                         break;
2933         }
2934
2935         /* Now copy what we have to the user */
2936         sret = trace_seq_to_user(&iter->seq, ubuf, cnt);
2937         if (iter->seq.readpos >= iter->seq.len)
2938                 trace_seq_init(&iter->seq);
2939
2940         /*
2941          * If there was nothing to send to user, inspite of consuming trace
2942          * entries, go back to wait for more entries.
2943          */
2944         if (sret == -EBUSY)
2945                 goto waitagain;
2946
2947 out:
2948         mutex_unlock(&iter->mutex);
2949
2950         return sret;
2951 }
2952
2953 static void tracing_pipe_buf_release(struct pipe_inode_info *pipe,
2954                                      struct pipe_buffer *buf)
2955 {
2956         __free_page(buf->page);
2957 }
2958
2959 static void tracing_spd_release_pipe(struct splice_pipe_desc *spd,
2960                                      unsigned int idx)
2961 {
2962         __free_page(spd->pages[idx]);
2963 }
2964
2965 static struct pipe_buf_operations tracing_pipe_buf_ops = {
2966         .can_merge              = 0,
2967         .map                    = generic_pipe_buf_map,
2968         .unmap                  = generic_pipe_buf_unmap,
2969         .confirm                = generic_pipe_buf_confirm,
2970         .release                = tracing_pipe_buf_release,
2971         .steal                  = generic_pipe_buf_steal,
2972         .get                    = generic_pipe_buf_get,
2973 };
2974
2975 static size_t
2976 tracing_fill_pipe_page(size_t rem, struct trace_iterator *iter)
2977 {
2978         size_t count;
2979         int ret;
2980
2981         /* Seq buffer is page-sized, exactly what we need. */
2982         for (;;) {
2983                 count = iter->seq.len;
2984                 ret = print_trace_line(iter);
2985                 count = iter->seq.len - count;
2986                 if (rem < count) {
2987                         rem = 0;
2988                         iter->seq.len -= count;
2989                         break;
2990                 }
2991                 if (ret == TRACE_TYPE_PARTIAL_LINE) {
2992                         iter->seq.len -= count;
2993                         break;
2994                 }
2995
2996                 trace_consume(iter);
2997                 rem -= count;
2998                 if (!find_next_entry_inc(iter)) {
2999                         rem = 0;
3000                         iter->ent = NULL;
3001                         break;
3002                 }
3003         }
3004
3005         return rem;
3006 }
3007
3008 static ssize_t tracing_splice_read_pipe(struct file *filp,
3009                                         loff_t *ppos,
3010                                         struct pipe_inode_info *pipe,
3011                                         size_t len,
3012                                         unsigned int flags)
3013 {
3014         struct page *pages[PIPE_BUFFERS];
3015         struct partial_page partial[PIPE_BUFFERS];
3016         struct trace_iterator *iter = filp->private_data;
3017         struct splice_pipe_desc spd = {
3018                 .pages          = pages,
3019                 .partial        = partial,
3020                 .nr_pages       = 0, /* This gets updated below. */
3021                 .flags          = flags,
3022                 .ops            = &tracing_pipe_buf_ops,
3023                 .spd_release    = tracing_spd_release_pipe,
3024         };
3025         static struct tracer *old_tracer;
3026         ssize_t ret;
3027         size_t rem;
3028         unsigned int i;
3029
3030         /* copy the tracer to avoid using a global lock all around */
3031         mutex_lock(&trace_types_lock);
3032         if (unlikely(old_tracer != current_trace && current_trace)) {
3033                 old_tracer = current_trace;
3034                 *iter->trace = *current_trace;
3035         }
3036         mutex_unlock(&trace_types_lock);
3037
3038         mutex_lock(&iter->mutex);
3039
3040         if (iter->trace->splice_read) {
3041                 ret = iter->trace->splice_read(iter, filp,
3042                                                ppos, pipe, len, flags);
3043                 if (ret)
3044                         goto out_err;
3045         }
3046
3047         ret = tracing_wait_pipe(filp);
3048         if (ret <= 0)
3049                 goto out_err;
3050
3051         if (!iter->ent && !find_next_entry_inc(iter)) {
3052                 ret = -EFAULT;
3053                 goto out_err;
3054         }
3055
3056         /* Fill as many pages as possible. */
3057         for (i = 0, rem = len; i < PIPE_BUFFERS && rem; i++) {
3058                 pages[i] = alloc_page(GFP_KERNEL);
3059                 if (!pages[i])
3060                         break;
3061
3062                 rem = tracing_fill_pipe_page(rem, iter);
3063
3064                 /* Copy the data into the page, so we can start over. */
3065                 ret = trace_seq_to_buffer(&iter->seq,
3066                                           page_address(pages[i]),
3067                                           iter->seq.len);
3068                 if (ret < 0) {
3069                         __free_page(pages[i]);
3070                         break;
3071                 }
3072                 partial[i].offset = 0;
3073                 partial[i].len = iter->seq.len;
3074
3075                 trace_seq_init(&iter->seq);
3076         }
3077
3078         mutex_unlock(&iter->mutex);
3079
3080         spd.nr_pages = i;
3081
3082         return splice_to_pipe(pipe, &spd);
3083
3084 out_err:
3085         mutex_unlock(&iter->mutex);
3086
3087         return ret;
3088 }
3089
3090 static ssize_t
3091 tracing_entries_read(struct file *filp, char __user *ubuf,
3092                      size_t cnt, loff_t *ppos)
3093 {
3094         struct trace_array *tr = filp->private_data;
3095         char buf[96];
3096         int r;
3097
3098         mutex_lock(&trace_types_lock);
3099         if (!ring_buffer_expanded)
3100                 r = sprintf(buf, "%lu (expanded: %lu)\n",
3101                             tr->entries >> 10,
3102                             trace_buf_size >> 10);
3103         else
3104                 r = sprintf(buf, "%lu\n", tr->entries >> 10);
3105         mutex_unlock(&trace_types_lock);
3106
3107         return simple_read_from_buffer(ubuf, cnt, ppos, buf, r);
3108 }
3109
3110 static ssize_t
3111 tracing_entries_write(struct file *filp, const char __user *ubuf,
3112                       size_t cnt, loff_t *ppos)
3113 {
3114         unsigned long val;
3115         char buf[64];
3116         int ret, cpu;
3117
3118         if (cnt >= sizeof(buf))
3119                 return -EINVAL;
3120
3121         if (copy_from_user(&buf, ubuf, cnt))
3122                 return -EFAULT;
3123
3124         buf[cnt] = 0;
3125
3126         ret = strict_strtoul(buf, 10, &val);
3127         if (ret < 0)
3128                 return ret;
3129
3130         /* must have at least 1 entry */
3131         if (!val)
3132                 return -EINVAL;
3133
3134         mutex_lock(&trace_types_lock);
3135
3136         tracing_stop();
3137
3138         /* disable all cpu buffers */
3139         for_each_tracing_cpu(cpu) {
3140                 if (global_trace.data[cpu])
3141                         atomic_inc(&global_trace.data[cpu]->disabled);
3142                 if (max_tr.data[cpu])
3143                         atomic_inc(&max_tr.data[cpu]->disabled);
3144         }
3145
3146         /* value is in KB */
3147         val <<= 10;
3148
3149         if (val != global_trace.entries) {
3150                 ret = tracing_resize_ring_buffer(val);
3151                 if (ret < 0) {
3152                         cnt = ret;
3153                         goto out;
3154                 }
3155         }
3156
3157         filp->f_pos += cnt;
3158
3159         /* If check pages failed, return ENOMEM */
3160         if (tracing_disabled)
3161                 cnt = -ENOMEM;
3162  out:
3163         for_each_tracing_cpu(cpu) {
3164                 if (global_trace.data[cpu])
3165                         atomic_dec(&global_trace.data[cpu]->disabled);
3166                 if (max_tr.data[cpu])
3167                         atomic_dec(&max_tr.data[cpu]->disabled);
3168         }
3169
3170         tracing_start();
3171         max_tr.entries = global_trace.entries;
3172         mutex_unlock(&trace_types_lock);
3173
3174         return cnt;
3175 }
3176
3177 static int mark_printk(const char *fmt, ...)
3178 {
3179         int ret;
3180         va_list args;
3181         va_start(args, fmt);
3182         ret = trace_vprintk(0, fmt, args);
3183         va_end(args);
3184         return ret;
3185 }
3186
3187 static ssize_t
3188 tracing_mark_write(struct file *filp, const char __user *ubuf,
3189                                         size_t cnt, loff_t *fpos)
3190 {
3191         char *buf;
3192         char *end;
3193
3194         if (tracing_disabled)
3195                 return -EINVAL;
3196
3197         if (cnt > TRACE_BUF_SIZE)
3198                 cnt = TRACE_BUF_SIZE;
3199
3200         buf = kmalloc(cnt + 1, GFP_KERNEL);
3201         if (buf == NULL)
3202                 return -ENOMEM;
3203
3204         if (copy_from_user(buf, ubuf, cnt)) {
3205                 kfree(buf);
3206                 return -EFAULT;
3207         }
3208
3209         /* Cut from the first nil or newline. */
3210         buf[cnt] = '\0';
3211         end = strchr(buf, '\n');
3212         if (end)
3213                 *end = '\0';
3214
3215         cnt = mark_printk("%s\n", buf);
3216         kfree(buf);
3217         *fpos += cnt;
3218
3219         return cnt;
3220 }
3221
3222 static const struct file_operations tracing_max_lat_fops = {
3223         .open           = tracing_open_generic,
3224         .read           = tracing_max_lat_read,
3225         .write          = tracing_max_lat_write,
3226 };
3227
3228 static const struct file_operations tracing_ctrl_fops = {
3229         .open           = tracing_open_generic,
3230         .read           = tracing_ctrl_read,
3231         .write          = tracing_ctrl_write,
3232 };
3233
3234 static const struct file_operations set_tracer_fops = {
3235         .open           = tracing_open_generic,
3236         .read           = tracing_set_trace_read,
3237         .write          = tracing_set_trace_write,
3238 };
3239
3240 static const struct file_operations tracing_pipe_fops = {
3241         .open           = tracing_open_pipe,
3242         .poll           = tracing_poll_pipe,
3243         .read           = tracing_read_pipe,
3244         .splice_read    = tracing_splice_read_pipe,
3245         .release        = tracing_release_pipe,
3246 };
3247
3248 static const struct file_operations tracing_entries_fops = {
3249         .open           = tracing_open_generic,
3250         .read           = tracing_entries_read,
3251         .write          = tracing_entries_write,
3252 };
3253
3254 static const struct file_operations tracing_mark_fops = {
3255         .open           = tracing_open_generic,
3256         .write          = tracing_mark_write,
3257 };
3258
3259 struct ftrace_buffer_info {
3260         struct trace_array      *tr;
3261         void                    *spare;
3262         int                     cpu;
3263         unsigned int            read;
3264 };
3265
3266 static int tracing_buffers_open(struct inode *inode, struct file *filp)
3267 {
3268         int cpu = (int)(long)inode->i_private;
3269         struct ftrace_buffer_info *info;
3270
3271         if (tracing_disabled)
3272                 return -ENODEV;
3273
3274         info = kzalloc(sizeof(*info), GFP_KERNEL);
3275         if (!info)
3276                 return -ENOMEM;
3277
3278         info->tr        = &global_trace;
3279         info->cpu       = cpu;
3280         info->spare     = NULL;
3281         /* Force reading ring buffer for first read */
3282         info->read      = (unsigned int)-1;
3283
3284         filp->private_data = info;
3285
3286         return nonseekable_open(inode, filp);
3287 }
3288
3289 static ssize_t
3290 tracing_buffers_read(struct file *filp, char __user *ubuf,
3291                      size_t count, loff_t *ppos)
3292 {
3293         struct ftrace_buffer_info *info = filp->private_data;
3294         unsigned int pos;
3295         ssize_t ret;
3296         size_t size;
3297
3298         if (!count)
3299                 return 0;
3300
3301         if (!info->spare)
3302                 info->spare = ring_buffer_alloc_read_page(info->tr->buffer);
3303         if (!info->spare)
3304                 return -ENOMEM;
3305
3306         /* Do we have previous read data to read? */
3307         if (info->read < PAGE_SIZE)
3308                 goto read;
3309
3310         info->read = 0;
3311
3312         ret = ring_buffer_read_page(info->tr->buffer,
3313                                     &info->spare,
3314                                     count,
3315                                     info->cpu, 0);
3316         if (ret < 0)
3317                 return 0;
3318
3319         pos = ring_buffer_page_len(info->spare);
3320
3321         if (pos < PAGE_SIZE)
3322                 memset(info->spare + pos, 0, PAGE_SIZE - pos);
3323
3324 read:
3325         size = PAGE_SIZE - info->read;
3326         if (size > count)
3327                 size = count;
3328
3329         ret = copy_to_user(ubuf, info->spare + info->read, size);
3330         if (ret == size)
3331                 return -EFAULT;
3332         size -= ret;
3333
3334         *ppos += size;
3335         info->read += size;
3336
3337         return size;
3338 }
3339
3340 static int tracing_buffers_release(struct inode *inode, struct file *file)
3341 {
3342         struct ftrace_buffer_info *info = file->private_data;
3343
3344         if (info->spare)
3345                 ring_buffer_free_read_page(info->tr->buffer, info->spare);
3346         kfree(info);
3347
3348         return 0;
3349 }
3350
3351 struct buffer_ref {
3352         struct ring_buffer      *buffer;
3353         void                    *page;
3354         int                     ref;
3355 };
3356
3357 static void buffer_pipe_buf_release(struct pipe_inode_info *pipe,
3358                                     struct pipe_buffer *buf)
3359 {
3360         struct buffer_ref *ref = (struct buffer_ref *)buf->private;
3361
3362         if (--ref->ref)
3363                 return;
3364
3365         ring_buffer_free_read_page(ref->buffer, ref->page);
3366         kfree(ref);
3367         buf->private = 0;
3368 }
3369
3370 static int buffer_pipe_buf_steal(struct pipe_inode_info *pipe,
3371                                  struct pipe_buffer *buf)
3372 {
3373         return 1;
3374 }
3375
3376 static void buffer_pipe_buf_get(struct pipe_inode_info *pipe,
3377                                 struct pipe_buffer *buf)
3378 {
3379         struct buffer_ref *ref = (struct buffer_ref *)buf->private;
3380
3381         ref->ref++;
3382 }
3383
3384 /* Pipe buffer operations for a buffer. */
3385 static struct pipe_buf_operations buffer_pipe_buf_ops = {
3386         .can_merge              = 0,
3387         .map                    = generic_pipe_buf_map,
3388         .unmap                  = generic_pipe_buf_unmap,
3389         .confirm                = generic_pipe_buf_confirm,
3390         .release                = buffer_pipe_buf_release,
3391         .steal                  = buffer_pipe_buf_steal,
3392         .get                    = buffer_pipe_buf_get,
3393 };
3394
3395 /*
3396  * Callback from splice_to_pipe(), if we need to release some pages
3397  * at the end of the spd in case we error'ed out in filling the pipe.
3398  */
3399 static void buffer_spd_release(struct splice_pipe_desc *spd, unsigned int i)
3400 {
3401         struct buffer_ref *ref =
3402                 (struct buffer_ref *)spd->partial[i].private;
3403
3404         if (--ref->ref)
3405                 return;
3406
3407         ring_buffer_free_read_page(ref->buffer, ref->page);
3408         kfree(ref);
3409         spd->partial[i].private = 0;
3410 }
3411
3412 static ssize_t
3413 tracing_buffers_splice_read(struct file *file, loff_t *ppos,
3414                             struct pipe_inode_info *pipe, size_t len,
3415                             unsigned int flags)
3416 {
3417         struct ftrace_buffer_info *info = file->private_data;
3418         struct partial_page partial[PIPE_BUFFERS];
3419         struct page *pages[PIPE_BUFFERS];
3420         struct splice_pipe_desc spd = {
3421                 .pages          = pages,
3422                 .partial        = partial,
3423                 .flags          = flags,
3424                 .ops            = &buffer_pipe_buf_ops,
3425                 .spd_release    = buffer_spd_release,
3426         };
3427         struct buffer_ref *ref;
3428         int size, i;
3429         size_t ret;
3430
3431         if (*ppos & (PAGE_SIZE - 1)) {
3432                 WARN_ONCE(1, "Ftrace: previous read must page-align\n");
3433                 return -EINVAL;
3434         }
3435
3436         if (len & (PAGE_SIZE - 1)) {
3437                 WARN_ONCE(1, "Ftrace: splice_read should page-align\n");
3438                 if (len < PAGE_SIZE)
3439                         return -EINVAL;
3440                 len &= PAGE_MASK;
3441         }
3442
3443         for (i = 0; i < PIPE_BUFFERS && len; i++, len -= PAGE_SIZE) {
3444                 struct page *page;
3445                 int r;
3446
3447                 ref = kzalloc(sizeof(*ref), GFP_KERNEL);
3448                 if (!ref)
3449                         break;
3450
3451                 ref->buffer = info->tr->buffer;
3452                 ref->page = ring_buffer_alloc_read_page(ref->buffer);
3453                 if (!ref->page) {
3454                         kfree(ref);
3455                         break;
3456                 }
3457
3458                 r = ring_buffer_read_page(ref->buffer, &ref->page,
3459                                           len, info->cpu, 0);
3460                 if (r < 0) {
3461                         ring_buffer_free_read_page(ref->buffer,
3462                                                    ref->page);
3463                         kfree(ref);
3464                         break;
3465                 }
3466
3467                 /*
3468                  * zero out any left over data, this is going to
3469                  * user land.
3470                  */
3471                 size = ring_buffer_page_len(ref->page);
3472                 if (size < PAGE_SIZE)
3473                         memset(ref->page + size, 0, PAGE_SIZE - size);
3474
3475                 page = virt_to_page(ref->page);
3476
3477                 spd.pages[i] = page;
3478                 spd.partial[i].len = PAGE_SIZE;
3479                 spd.partial[i].offset = 0;
3480                 spd.partial[i].private = (unsigned long)ref;
3481                 spd.nr_pages++;
3482                 *ppos += PAGE_SIZE;
3483         }
3484
3485         spd.nr_pages = i;
3486
3487         /* did we read anything? */
3488         if (!spd.nr_pages) {
3489                 if (flags & SPLICE_F_NONBLOCK)
3490                         ret = -EAGAIN;
3491                 else
3492                         ret = 0;
3493                 /* TODO: block */
3494                 return ret;
3495         }
3496
3497         ret = splice_to_pipe(pipe, &spd);
3498
3499         return ret;
3500 }
3501
3502 static const struct file_operations tracing_buffers_fops = {
3503         .open           = tracing_buffers_open,
3504         .read           = tracing_buffers_read,
3505         .release        = tracing_buffers_release,
3506         .splice_read    = tracing_buffers_splice_read,
3507         .llseek         = no_llseek,
3508 };
3509
3510 #ifdef CONFIG_DYNAMIC_FTRACE
3511
3512 int __weak ftrace_arch_read_dyn_info(char *buf, int size)
3513 {
3514         return 0;
3515 }
3516
3517 static ssize_t
3518 tracing_read_dyn_info(struct file *filp, char __user *ubuf,
3519                   size_t cnt, loff_t *ppos)
3520 {
3521         static char ftrace_dyn_info_buffer[1024];
3522         static DEFINE_MUTEX(dyn_info_mutex);
3523         unsigned long *p = filp->private_data;
3524         char *buf = ftrace_dyn_info_buffer;
3525         int size = ARRAY_SIZE(ftrace_dyn_info_buffer);
3526         int r;
3527
3528         mutex_lock(&dyn_info_mutex);
3529         r = sprintf(buf, "%ld ", *p);
3530
3531         r += ftrace_arch_read_dyn_info(buf+r, (size-1)-r);
3532         buf[r++] = '\n';