Commit | Line | Data |
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bc0c38d1 SR |
1 | #ifndef _LINUX_KERNEL_TRACE_H |
2 | #define _LINUX_KERNEL_TRACE_H | |
3 | ||
4 | #include <linux/fs.h> | |
5 | #include <asm/atomic.h> | |
6 | #include <linux/sched.h> | |
7 | #include <linux/clocksource.h> | |
3928a8a2 | 8 | #include <linux/ring_buffer.h> |
bd8ac686 | 9 | #include <linux/mmiotrace.h> |
d13744cd | 10 | #include <linux/ftrace.h> |
3f5ec136 | 11 | #include <trace/boot.h> |
bc0c38d1 | 12 | |
72829bc3 TG |
13 | enum trace_type { |
14 | __TRACE_FIRST_TYPE = 0, | |
15 | ||
16 | TRACE_FN, | |
17 | TRACE_CTX, | |
18 | TRACE_WAKE, | |
dd0e545f | 19 | TRACE_CONT, |
72829bc3 | 20 | TRACE_STACK, |
dd0e545f | 21 | TRACE_PRINT, |
72829bc3 | 22 | TRACE_SPECIAL, |
bd8ac686 PP |
23 | TRACE_MMIO_RW, |
24 | TRACE_MMIO_MAP, | |
52f232cb | 25 | TRACE_UNLIKELY, |
74239072 FW |
26 | TRACE_BOOT_CALL, |
27 | TRACE_BOOT_RET, | |
15e6cb36 | 28 | TRACE_FN_RET, |
72829bc3 TG |
29 | |
30 | __TRACE_LAST_TYPE | |
31 | }; | |
32 | ||
777e208d SR |
33 | /* |
34 | * The trace entry - the most basic unit of tracing. This is what | |
35 | * is printed in the end as a single line in the trace output, such as: | |
36 | * | |
37 | * bash-15816 [01] 235.197585: idle_cpu <- irq_enter | |
38 | */ | |
39 | struct trace_entry { | |
40 | unsigned char type; | |
41 | unsigned char cpu; | |
42 | unsigned char flags; | |
43 | unsigned char preempt_count; | |
44 | int pid; | |
45 | }; | |
46 | ||
bc0c38d1 SR |
47 | /* |
48 | * Function trace entry - function address and parent function addres: | |
49 | */ | |
50 | struct ftrace_entry { | |
777e208d | 51 | struct trace_entry ent; |
bc0c38d1 SR |
52 | unsigned long ip; |
53 | unsigned long parent_ip; | |
54 | }; | |
15e6cb36 FW |
55 | |
56 | /* Function return entry */ | |
57 | struct ftrace_ret_entry { | |
58 | struct trace_entry ent; | |
59 | unsigned long ip; | |
60 | unsigned long parent_ip; | |
61 | unsigned long long calltime; | |
62 | unsigned long long rettime; | |
63 | }; | |
d13744cd | 64 | extern struct tracer boot_tracer; |
bc0c38d1 SR |
65 | |
66 | /* | |
67 | * Context switch trace entry - which task (and prio) we switched from/to: | |
68 | */ | |
69 | struct ctx_switch_entry { | |
777e208d | 70 | struct trace_entry ent; |
bc0c38d1 SR |
71 | unsigned int prev_pid; |
72 | unsigned char prev_prio; | |
73 | unsigned char prev_state; | |
74 | unsigned int next_pid; | |
75 | unsigned char next_prio; | |
bac524d3 | 76 | unsigned char next_state; |
80b5e940 | 77 | unsigned int next_cpu; |
bc0c38d1 SR |
78 | }; |
79 | ||
f0a920d5 IM |
80 | /* |
81 | * Special (free-form) trace entry: | |
82 | */ | |
83 | struct special_entry { | |
777e208d | 84 | struct trace_entry ent; |
f0a920d5 IM |
85 | unsigned long arg1; |
86 | unsigned long arg2; | |
87 | unsigned long arg3; | |
88 | }; | |
89 | ||
86387f7e IM |
90 | /* |
91 | * Stack-trace entry: | |
92 | */ | |
93 | ||
74f4e369 | 94 | #define FTRACE_STACK_ENTRIES 8 |
86387f7e IM |
95 | |
96 | struct stack_entry { | |
777e208d | 97 | struct trace_entry ent; |
86387f7e IM |
98 | unsigned long caller[FTRACE_STACK_ENTRIES]; |
99 | }; | |
100 | ||
dd0e545f SR |
101 | /* |
102 | * ftrace_printk entry: | |
103 | */ | |
104 | struct print_entry { | |
777e208d | 105 | struct trace_entry ent; |
dd0e545f SR |
106 | unsigned long ip; |
107 | char buf[]; | |
108 | }; | |
109 | ||
777e208d SR |
110 | #define TRACE_OLD_SIZE 88 |
111 | ||
112 | struct trace_field_cont { | |
113 | unsigned char type; | |
114 | /* Temporary till we get rid of this completely */ | |
115 | char buf[TRACE_OLD_SIZE - 1]; | |
116 | }; | |
117 | ||
118 | struct trace_mmiotrace_rw { | |
119 | struct trace_entry ent; | |
120 | struct mmiotrace_rw rw; | |
121 | }; | |
122 | ||
123 | struct trace_mmiotrace_map { | |
124 | struct trace_entry ent; | |
125 | struct mmiotrace_map map; | |
126 | }; | |
127 | ||
74239072 | 128 | struct trace_boot_call { |
777e208d | 129 | struct trace_entry ent; |
74239072 FW |
130 | struct boot_trace_call boot_call; |
131 | }; | |
132 | ||
133 | struct trace_boot_ret { | |
134 | struct trace_entry ent; | |
135 | struct boot_trace_ret boot_ret; | |
777e208d SR |
136 | }; |
137 | ||
52f232cb SR |
138 | #define TRACE_FUNC_SIZE 30 |
139 | #define TRACE_FILE_SIZE 20 | |
140 | struct trace_unlikely { | |
141 | struct trace_entry ent; | |
142 | unsigned line; | |
143 | char func[TRACE_FUNC_SIZE+1]; | |
144 | char file[TRACE_FILE_SIZE+1]; | |
145 | char correct; | |
146 | }; | |
147 | ||
fc5e27ae PP |
148 | /* |
149 | * trace_flag_type is an enumeration that holds different | |
150 | * states when a trace occurs. These are: | |
9244489a SR |
151 | * IRQS_OFF - interrupts were disabled |
152 | * IRQS_NOSUPPORT - arch does not support irqs_disabled_flags | |
153 | * NEED_RESCED - reschedule is requested | |
154 | * HARDIRQ - inside an interrupt handler | |
155 | * SOFTIRQ - inside a softirq handler | |
156 | * CONT - multiple entries hold the trace item | |
fc5e27ae PP |
157 | */ |
158 | enum trace_flag_type { | |
159 | TRACE_FLAG_IRQS_OFF = 0x01, | |
9244489a SR |
160 | TRACE_FLAG_IRQS_NOSUPPORT = 0x02, |
161 | TRACE_FLAG_NEED_RESCHED = 0x04, | |
162 | TRACE_FLAG_HARDIRQ = 0x08, | |
163 | TRACE_FLAG_SOFTIRQ = 0x10, | |
164 | TRACE_FLAG_CONT = 0x20, | |
fc5e27ae PP |
165 | }; |
166 | ||
5bf9a1ee | 167 | #define TRACE_BUF_SIZE 1024 |
bc0c38d1 SR |
168 | |
169 | /* | |
170 | * The CPU trace array - it consists of thousands of trace entries | |
171 | * plus some other descriptor data: (for example which task started | |
172 | * the trace, etc.) | |
173 | */ | |
174 | struct trace_array_cpu { | |
bc0c38d1 | 175 | atomic_t disabled; |
4e3c3333 | 176 | |
c7aafc54 | 177 | /* these fields get copied into max-trace: */ |
c7aafc54 | 178 | unsigned long trace_idx; |
53d0aa77 | 179 | unsigned long overrun; |
bc0c38d1 SR |
180 | unsigned long saved_latency; |
181 | unsigned long critical_start; | |
182 | unsigned long critical_end; | |
183 | unsigned long critical_sequence; | |
184 | unsigned long nice; | |
185 | unsigned long policy; | |
186 | unsigned long rt_priority; | |
187 | cycle_t preempt_timestamp; | |
188 | pid_t pid; | |
189 | uid_t uid; | |
190 | char comm[TASK_COMM_LEN]; | |
191 | }; | |
192 | ||
193 | struct trace_iterator; | |
194 | ||
195 | /* | |
196 | * The trace array - an array of per-CPU trace arrays. This is the | |
197 | * highest level data structure that individual tracers deal with. | |
198 | * They have on/off state as well: | |
199 | */ | |
200 | struct trace_array { | |
3928a8a2 | 201 | struct ring_buffer *buffer; |
bc0c38d1 | 202 | unsigned long entries; |
bc0c38d1 SR |
203 | int cpu; |
204 | cycle_t time_start; | |
b3806b43 | 205 | struct task_struct *waiter; |
bc0c38d1 SR |
206 | struct trace_array_cpu *data[NR_CPUS]; |
207 | }; | |
208 | ||
7104f300 SR |
209 | #define FTRACE_CMP_TYPE(var, type) \ |
210 | __builtin_types_compatible_p(typeof(var), type *) | |
211 | ||
212 | #undef IF_ASSIGN | |
213 | #define IF_ASSIGN(var, entry, etype, id) \ | |
214 | if (FTRACE_CMP_TYPE(var, etype)) { \ | |
215 | var = (typeof(var))(entry); \ | |
216 | WARN_ON(id && (entry)->type != id); \ | |
217 | break; \ | |
218 | } | |
219 | ||
220 | /* Will cause compile errors if type is not found. */ | |
221 | extern void __ftrace_bad_type(void); | |
222 | ||
223 | /* | |
224 | * The trace_assign_type is a verifier that the entry type is | |
225 | * the same as the type being assigned. To add new types simply | |
226 | * add a line with the following format: | |
227 | * | |
228 | * IF_ASSIGN(var, ent, type, id); | |
229 | * | |
230 | * Where "type" is the trace type that includes the trace_entry | |
231 | * as the "ent" item. And "id" is the trace identifier that is | |
232 | * used in the trace_type enum. | |
233 | * | |
234 | * If the type can have more than one id, then use zero. | |
235 | */ | |
236 | #define trace_assign_type(var, ent) \ | |
237 | do { \ | |
238 | IF_ASSIGN(var, ent, struct ftrace_entry, TRACE_FN); \ | |
239 | IF_ASSIGN(var, ent, struct ctx_switch_entry, 0); \ | |
240 | IF_ASSIGN(var, ent, struct trace_field_cont, TRACE_CONT); \ | |
241 | IF_ASSIGN(var, ent, struct stack_entry, TRACE_STACK); \ | |
242 | IF_ASSIGN(var, ent, struct print_entry, TRACE_PRINT); \ | |
243 | IF_ASSIGN(var, ent, struct special_entry, 0); \ | |
244 | IF_ASSIGN(var, ent, struct trace_mmiotrace_rw, \ | |
245 | TRACE_MMIO_RW); \ | |
246 | IF_ASSIGN(var, ent, struct trace_mmiotrace_map, \ | |
247 | TRACE_MMIO_MAP); \ | |
74239072 FW |
248 | IF_ASSIGN(var, ent, struct trace_boot_call, TRACE_BOOT_CALL);\ |
249 | IF_ASSIGN(var, ent, struct trace_boot_ret, TRACE_BOOT_RET);\ | |
52f232cb | 250 | IF_ASSIGN(var, ent, struct trace_unlikely, TRACE_UNLIKELY); \ |
74239072 | 251 | IF_ASSIGN(var, ent, struct ftrace_ret_entry, TRACE_FN_RET);\ |
7104f300 SR |
252 | __ftrace_bad_type(); \ |
253 | } while (0) | |
2c4f035f FW |
254 | |
255 | /* Return values for print_line callback */ | |
256 | enum print_line_t { | |
257 | TRACE_TYPE_PARTIAL_LINE = 0, /* Retry after flushing the seq */ | |
258 | TRACE_TYPE_HANDLED = 1, | |
259 | TRACE_TYPE_UNHANDLED = 2 /* Relay to other output functions */ | |
260 | }; | |
261 | ||
bc0c38d1 SR |
262 | /* |
263 | * A specific tracer, represented by methods that operate on a trace array: | |
264 | */ | |
265 | struct tracer { | |
266 | const char *name; | |
267 | void (*init)(struct trace_array *tr); | |
268 | void (*reset)(struct trace_array *tr); | |
9036990d SR |
269 | void (*start)(struct trace_array *tr); |
270 | void (*stop)(struct trace_array *tr); | |
bc0c38d1 | 271 | void (*open)(struct trace_iterator *iter); |
107bad8b | 272 | void (*pipe_open)(struct trace_iterator *iter); |
bc0c38d1 | 273 | void (*close)(struct trace_iterator *iter); |
107bad8b SR |
274 | ssize_t (*read)(struct trace_iterator *iter, |
275 | struct file *filp, char __user *ubuf, | |
276 | size_t cnt, loff_t *ppos); | |
60a11774 SR |
277 | #ifdef CONFIG_FTRACE_STARTUP_TEST |
278 | int (*selftest)(struct tracer *trace, | |
279 | struct trace_array *tr); | |
280 | #endif | |
2c4f035f | 281 | enum print_line_t (*print_line)(struct trace_iterator *iter); |
bc0c38d1 SR |
282 | struct tracer *next; |
283 | int print_max; | |
284 | }; | |
285 | ||
214023c3 SR |
286 | struct trace_seq { |
287 | unsigned char buffer[PAGE_SIZE]; | |
288 | unsigned int len; | |
6c6c2796 | 289 | unsigned int readpos; |
214023c3 SR |
290 | }; |
291 | ||
bc0c38d1 SR |
292 | /* |
293 | * Trace iterator - used by printout routines who present trace | |
294 | * results to users and which routines might sleep, etc: | |
295 | */ | |
296 | struct trace_iterator { | |
297 | struct trace_array *tr; | |
298 | struct tracer *trace; | |
107bad8b | 299 | void *private; |
3928a8a2 | 300 | struct ring_buffer_iter *buffer_iter[NR_CPUS]; |
4e3c3333 | 301 | |
53d0aa77 SR |
302 | /* The below is zeroed out in pipe_read */ |
303 | struct trace_seq seq; | |
bc0c38d1 | 304 | struct trace_entry *ent; |
4e3c3333 | 305 | int cpu; |
3928a8a2 | 306 | u64 ts; |
4e3c3333 | 307 | |
bc0c38d1 SR |
308 | unsigned long iter_flags; |
309 | loff_t pos; | |
4c11d7ae | 310 | long idx; |
a309720c SR |
311 | |
312 | cpumask_t started; | |
bc0c38d1 SR |
313 | }; |
314 | ||
9036990d | 315 | int tracing_is_enabled(void); |
45dcd8b8 | 316 | void trace_wake_up(void); |
3928a8a2 | 317 | void tracing_reset(struct trace_array *tr, int cpu); |
bc0c38d1 SR |
318 | int tracing_open_generic(struct inode *inode, struct file *filp); |
319 | struct dentry *tracing_init_dentry(void); | |
d618b3e6 IM |
320 | void init_tracer_sysprof_debugfs(struct dentry *d_tracer); |
321 | ||
45dcd8b8 PP |
322 | struct trace_entry *tracing_get_trace_entry(struct trace_array *tr, |
323 | struct trace_array_cpu *data); | |
324 | void tracing_generic_entry_update(struct trace_entry *entry, | |
38697053 SR |
325 | unsigned long flags, |
326 | int pc); | |
45dcd8b8 | 327 | |
bc0c38d1 SR |
328 | void ftrace(struct trace_array *tr, |
329 | struct trace_array_cpu *data, | |
330 | unsigned long ip, | |
331 | unsigned long parent_ip, | |
38697053 | 332 | unsigned long flags, int pc); |
bc0c38d1 SR |
333 | void tracing_sched_switch_trace(struct trace_array *tr, |
334 | struct trace_array_cpu *data, | |
335 | struct task_struct *prev, | |
336 | struct task_struct *next, | |
38697053 | 337 | unsigned long flags, int pc); |
bc0c38d1 | 338 | void tracing_record_cmdline(struct task_struct *tsk); |
57422797 IM |
339 | |
340 | void tracing_sched_wakeup_trace(struct trace_array *tr, | |
341 | struct trace_array_cpu *data, | |
342 | struct task_struct *wakee, | |
343 | struct task_struct *cur, | |
38697053 | 344 | unsigned long flags, int pc); |
f0a920d5 IM |
345 | void trace_special(struct trace_array *tr, |
346 | struct trace_array_cpu *data, | |
347 | unsigned long arg1, | |
348 | unsigned long arg2, | |
38697053 | 349 | unsigned long arg3, int pc); |
6fb44b71 SR |
350 | void trace_function(struct trace_array *tr, |
351 | struct trace_array_cpu *data, | |
352 | unsigned long ip, | |
353 | unsigned long parent_ip, | |
38697053 | 354 | unsigned long flags, int pc); |
15e6cb36 FW |
355 | void |
356 | trace_function_return(struct ftrace_retfunc *trace); | |
bc0c38d1 | 357 | |
41bc8144 SR |
358 | void tracing_start_cmdline_record(void); |
359 | void tracing_stop_cmdline_record(void); | |
e168e051 SR |
360 | void tracing_sched_switch_assign_trace(struct trace_array *tr); |
361 | void tracing_stop_sched_switch_record(void); | |
362 | void tracing_start_sched_switch_record(void); | |
bc0c38d1 SR |
363 | int register_tracer(struct tracer *type); |
364 | void unregister_tracer(struct tracer *type); | |
365 | ||
366 | extern unsigned long nsecs_to_usecs(unsigned long nsecs); | |
367 | ||
368 | extern unsigned long tracing_max_latency; | |
369 | extern unsigned long tracing_thresh; | |
370 | ||
371 | void update_max_tr(struct trace_array *tr, struct task_struct *tsk, int cpu); | |
372 | void update_max_tr_single(struct trace_array *tr, | |
373 | struct task_struct *tsk, int cpu); | |
374 | ||
e309b41d | 375 | extern cycle_t ftrace_now(int cpu); |
bc0c38d1 | 376 | |
606576ce | 377 | #ifdef CONFIG_FUNCTION_TRACER |
001b6767 SR |
378 | void tracing_start_function_trace(void); |
379 | void tracing_stop_function_trace(void); | |
380 | #else | |
381 | # define tracing_start_function_trace() do { } while (0) | |
382 | # define tracing_stop_function_trace() do { } while (0) | |
383 | #endif | |
384 | ||
bc0c38d1 SR |
385 | #ifdef CONFIG_CONTEXT_SWITCH_TRACER |
386 | typedef void | |
387 | (*tracer_switch_func_t)(void *private, | |
5b82a1b0 | 388 | void *__rq, |
bc0c38d1 SR |
389 | struct task_struct *prev, |
390 | struct task_struct *next); | |
391 | ||
392 | struct tracer_switch_ops { | |
393 | tracer_switch_func_t func; | |
394 | void *private; | |
395 | struct tracer_switch_ops *next; | |
396 | }; | |
397 | ||
bc0c38d1 SR |
398 | #endif /* CONFIG_CONTEXT_SWITCH_TRACER */ |
399 | ||
400 | #ifdef CONFIG_DYNAMIC_FTRACE | |
401 | extern unsigned long ftrace_update_tot_cnt; | |
d05cdb25 SR |
402 | #define DYN_FTRACE_TEST_NAME trace_selftest_dynamic_test_func |
403 | extern int DYN_FTRACE_TEST_NAME(void); | |
bc0c38d1 SR |
404 | #endif |
405 | ||
60a11774 | 406 | #ifdef CONFIG_FTRACE_STARTUP_TEST |
60a11774 SR |
407 | extern int trace_selftest_startup_function(struct tracer *trace, |
408 | struct trace_array *tr); | |
60a11774 SR |
409 | extern int trace_selftest_startup_irqsoff(struct tracer *trace, |
410 | struct trace_array *tr); | |
60a11774 SR |
411 | extern int trace_selftest_startup_preemptoff(struct tracer *trace, |
412 | struct trace_array *tr); | |
60a11774 SR |
413 | extern int trace_selftest_startup_preemptirqsoff(struct tracer *trace, |
414 | struct trace_array *tr); | |
60a11774 SR |
415 | extern int trace_selftest_startup_wakeup(struct tracer *trace, |
416 | struct trace_array *tr); | |
fb1b6d8b SN |
417 | extern int trace_selftest_startup_nop(struct tracer *trace, |
418 | struct trace_array *tr); | |
60a11774 SR |
419 | extern int trace_selftest_startup_sched_switch(struct tracer *trace, |
420 | struct trace_array *tr); | |
a6dd24f8 IM |
421 | extern int trace_selftest_startup_sysprof(struct tracer *trace, |
422 | struct trace_array *tr); | |
60a11774 SR |
423 | #endif /* CONFIG_FTRACE_STARTUP_TEST */ |
424 | ||
c7aafc54 | 425 | extern void *head_page(struct trace_array_cpu *data); |
72829bc3 | 426 | extern int trace_seq_printf(struct trace_seq *s, const char *fmt, ...); |
fc5e27ae PP |
427 | extern void trace_seq_print_cont(struct trace_seq *s, |
428 | struct trace_iterator *iter); | |
15e6cb36 FW |
429 | |
430 | extern int | |
431 | seq_print_ip_sym(struct trace_seq *s, unsigned long ip, | |
432 | unsigned long sym_flags); | |
6c6c2796 PP |
433 | extern ssize_t trace_seq_to_user(struct trace_seq *s, char __user *ubuf, |
434 | size_t cnt); | |
72829bc3 | 435 | extern long ns2usecs(cycle_t nsec); |
801fe400 | 436 | extern int trace_vprintk(unsigned long ip, const char *fmt, va_list args); |
c7aafc54 | 437 | |
4e655519 IM |
438 | extern unsigned long trace_flags; |
439 | ||
15e6cb36 FW |
440 | /* Standard output formatting function used for function return traces */ |
441 | #ifdef CONFIG_FUNCTION_RET_TRACER | |
442 | extern enum print_line_t print_return_function(struct trace_iterator *iter); | |
443 | #else | |
444 | static inline enum print_line_t | |
445 | print_return_function(struct trace_iterator *iter) | |
446 | { | |
447 | return TRACE_TYPE_UNHANDLED; | |
448 | } | |
449 | #endif | |
450 | ||
4fcdae83 SR |
451 | /* |
452 | * trace_iterator_flags is an enumeration that defines bit | |
453 | * positions into trace_flags that controls the output. | |
454 | * | |
455 | * NOTE: These bits must match the trace_options array in | |
456 | * trace.c. | |
457 | */ | |
4e655519 IM |
458 | enum trace_iterator_flags { |
459 | TRACE_ITER_PRINT_PARENT = 0x01, | |
460 | TRACE_ITER_SYM_OFFSET = 0x02, | |
461 | TRACE_ITER_SYM_ADDR = 0x04, | |
462 | TRACE_ITER_VERBOSE = 0x08, | |
463 | TRACE_ITER_RAW = 0x10, | |
464 | TRACE_ITER_HEX = 0x20, | |
465 | TRACE_ITER_BIN = 0x40, | |
466 | TRACE_ITER_BLOCK = 0x80, | |
467 | TRACE_ITER_STACKTRACE = 0x100, | |
4ac3ba41 | 468 | TRACE_ITER_SCHED_TREE = 0x200, |
f09ce573 | 469 | TRACE_ITER_PRINTK = 0x400, |
b2a866f9 | 470 | TRACE_ITER_PREEMPTONLY = 0x800, |
52f232cb SR |
471 | #ifdef CONFIG_UNLIKELY_TRACER |
472 | TRACE_ITER_UNLIKELY = 0x1000, | |
473 | #endif | |
4e655519 IM |
474 | }; |
475 | ||
15e6cb36 FW |
476 | /* |
477 | * TRACE_ITER_SYM_MASK masks the options in trace_flags that | |
478 | * control the output of kernel symbols. | |
479 | */ | |
480 | #define TRACE_ITER_SYM_MASK \ | |
481 | (TRACE_ITER_PRINT_PARENT|TRACE_ITER_SYM_OFFSET|TRACE_ITER_SYM_ADDR) | |
482 | ||
43a15386 FW |
483 | extern struct tracer nop_trace; |
484 | ||
8f0a056f SR |
485 | /** |
486 | * ftrace_preempt_disable - disable preemption scheduler safe | |
487 | * | |
488 | * When tracing can happen inside the scheduler, there exists | |
489 | * cases that the tracing might happen before the need_resched | |
490 | * flag is checked. If this happens and the tracer calls | |
491 | * preempt_enable (after a disable), a schedule might take place | |
492 | * causing an infinite recursion. | |
493 | * | |
494 | * To prevent this, we read the need_recshed flag before | |
495 | * disabling preemption. When we want to enable preemption we | |
496 | * check the flag, if it is set, then we call preempt_enable_no_resched. | |
497 | * Otherwise, we call preempt_enable. | |
498 | * | |
499 | * The rational for doing the above is that if need resched is set | |
500 | * and we have yet to reschedule, we are either in an atomic location | |
501 | * (where we do not need to check for scheduling) or we are inside | |
502 | * the scheduler and do not want to resched. | |
503 | */ | |
504 | static inline int ftrace_preempt_disable(void) | |
505 | { | |
506 | int resched; | |
507 | ||
508 | resched = need_resched(); | |
509 | preempt_disable_notrace(); | |
510 | ||
511 | return resched; | |
512 | } | |
513 | ||
514 | /** | |
515 | * ftrace_preempt_enable - enable preemption scheduler safe | |
516 | * @resched: the return value from ftrace_preempt_disable | |
517 | * | |
518 | * This is a scheduler safe way to enable preemption and not miss | |
519 | * any preemption checks. The disabled saved the state of preemption. | |
520 | * If resched is set, then we were either inside an atomic or | |
521 | * are inside the scheduler (we would have already scheduled | |
522 | * otherwise). In this case, we do not want to call normal | |
523 | * preempt_enable, but preempt_enable_no_resched instead. | |
524 | */ | |
525 | static inline void ftrace_preempt_enable(int resched) | |
526 | { | |
527 | if (resched) | |
528 | preempt_enable_no_resched_notrace(); | |
529 | else | |
530 | preempt_enable_notrace(); | |
531 | } | |
532 | ||
52f232cb SR |
533 | #ifdef CONFIG_UNLIKELY_TRACER |
534 | extern int enable_unlikely_tracing(struct trace_array *tr); | |
535 | extern void disable_unlikely_tracing(void); | |
536 | static inline int trace_unlikely_enable(struct trace_array *tr) | |
537 | { | |
538 | if (trace_flags & TRACE_ITER_UNLIKELY) | |
539 | return enable_unlikely_tracing(tr); | |
540 | return 0; | |
541 | } | |
542 | static inline void trace_unlikely_disable(void) | |
543 | { | |
544 | /* due to races, always disable */ | |
545 | disable_unlikely_tracing(); | |
546 | } | |
547 | #else | |
548 | static inline int trace_unlikely_enable(struct trace_array *tr) | |
549 | { | |
550 | return 0; | |
551 | } | |
552 | static inline void trace_unlikely_disable(void) | |
553 | { | |
554 | } | |
555 | #endif /* CONFIG_UNLIKELY_TRACER */ | |
556 | ||
bc0c38d1 | 557 | #endif /* _LINUX_KERNEL_TRACE_H */ |