projects/linux·blob v7.2 · refs

1332 lines · 43.2 KiB

1# SPDX-License-Identifier: GPL-2.0-only
2#
3# Architectures that offer an FUNCTION_TRACER implementation should
4# select HAVE_FUNCTION_TRACER:
5#
6
7config USER_STACKTRACE_SUPPORT
8 bool
9
10config NOP_TRACER
11 bool
12
13config HAVE_RETHOOK
14 bool
15
16config RETHOOK
17 bool
18 depends on HAVE_RETHOOK
19 help
20 Enable generic return hooking feature. This is an internal
21 API, which will be used by other function-entry hooking
22 features like fprobe and kprobes.
23
24config HAVE_FUNCTION_TRACER
25 bool
26 help
27 See Documentation/trace/ftrace-design.rst
28
29config HAVE_FUNCTION_GRAPH_TRACER
30 bool
31 help
32 See Documentation/trace/ftrace-design.rst
33
34config HAVE_FUNCTION_GRAPH_FREGS
35 bool
36
37config HAVE_FTRACE_GRAPH_FUNC
38 bool
39 help
40 True if ftrace_graph_func() is defined.
41
42config HAVE_DYNAMIC_FTRACE
43 bool
44 help
45 See Documentation/trace/ftrace-design.rst
46
47config HAVE_DYNAMIC_FTRACE_WITH_REGS
48 bool
49
50config HAVE_DYNAMIC_FTRACE_WITH_DIRECT_CALLS
51 bool
52
53config HAVE_SINGLE_FTRACE_DIRECT_OPS
54 bool
55
56config HAVE_DYNAMIC_FTRACE_WITH_CALL_OPS
57 bool
58
59config HAVE_EXTRA_IPI_TRACEPOINTS
60 bool
61 help
62 For architectures that use ipi_raise, ipi_entry and ipi_exit
63 tracepoints.
64
65config HAVE_DYNAMIC_FTRACE_WITH_ARGS
66 bool
67 help
68 If this is set, then arguments and stack can be found from
69 the ftrace_regs passed into the function callback regs parameter
70 by default, even without setting the REGS flag in the ftrace_ops.
71 This allows for use of ftrace_regs_get_argument() and
72 ftrace_regs_get_stack_pointer().
73
74config HAVE_FTRACE_REGS_HAVING_PT_REGS
75 bool
76 help
77 If this is set, ftrace_regs has pt_regs, thus it can convert to
78 pt_regs without allocating memory.
79
80config HAVE_DYNAMIC_FTRACE_NO_PATCHABLE
81 bool
82 help
83 If the architecture generates __patchable_function_entries sections
84 but does not want them included in the ftrace locations.
85
86config HAVE_DYNAMIC_FTRACE_WITH_JMP
87 bool
88 help
89 If the architecture supports to replace the __fentry__ with a
90 "jmp" instruction.
91
92config HAVE_SYSCALL_TRACEPOINTS
93 bool
94 help
95 See Documentation/trace/ftrace-design.rst
96
97config HAVE_FENTRY
98 bool
99 help
100 Arch supports the gcc options -pg with -mfentry
101
102config HAVE_NOP_MCOUNT
103 bool
104 help
105 Arch supports the gcc options -pg with -mrecord-mcount and -nop-mcount
106
107config HAVE_OBJTOOL_MCOUNT
108 bool
109 help
110 Arch supports objtool --mcount
111
112config HAVE_OBJTOOL_NOP_MCOUNT
113 bool
114 help
115 Arch supports the objtool options --mcount with --mnop.
116 An architecture can select this if it wants to enable nop'ing
117 of ftrace locations.
118
119config HAVE_C_RECORDMCOUNT
120 bool
121 help
122 C version of recordmcount available?
123
124config HAVE_BUILDTIME_MCOUNT_SORT
125 bool
126 help
127 An architecture selects this if it sorts the mcount_loc section
128 at build time.
129
130config BUILDTIME_MCOUNT_SORT
131 bool
132 default y
133 depends on HAVE_BUILDTIME_MCOUNT_SORT && DYNAMIC_FTRACE
134 help
135 Sort the mcount_loc section at build time.
136
137config TRACER_MAX_TRACE
138 bool
139 select TRACER_SNAPSHOT
140
141config TRACE_CLOCK
142 bool
143
144config RING_BUFFER
145 bool
146 select TRACE_CLOCK
147 select IRQ_WORK
148
149config EVENT_TRACING
150 select CONTEXT_SWITCH_TRACER
151 select GLOB
152 bool
153
154config CONTEXT_SWITCH_TRACER
155 bool
156
157config RING_BUFFER_ALLOW_SWAP
158 bool
159 help
160 Allow the use of ring_buffer_swap_cpu.
161 Adds a very slight overhead to tracing when enabled.
162
163config PREEMPTIRQ_TRACEPOINTS
164 bool
165 depends on TRACE_PREEMPT_TOGGLE || TRACE_IRQFLAGS
166 select TRACING
167 default y
168 help
169 Create preempt/irq toggle tracepoints if needed, so that other parts
170 of the kernel can use them to generate or add hooks to them.
171
172# All tracer options should select GENERIC_TRACER. For those options that are
173# enabled by all tracers (context switch and event tracer) they select TRACING.
174# This allows those options to appear when no other tracer is selected. But the
175# options do not appear when something else selects it. We need the two options
176# GENERIC_TRACER and TRACING to avoid circular dependencies to accomplish the
177# hiding of the automatic options.
178
179config TRACING
180 bool
181 select RING_BUFFER
182 select STACKTRACE if STACKTRACE_SUPPORT
183 select TRACEPOINTS
184 select NOP_TRACER
185 select BINARY_PRINTF
186 select EVENT_TRACING
187 select TRACE_CLOCK
188 select NEED_TASKS_RCU
189
190config GENERIC_TRACER
191 bool
192 select TRACING
193
194#
195# Minimum requirements an architecture has to meet for us to
196# be able to offer generic tracing facilities:
197#
198config TRACING_SUPPORT
199 bool
200 depends on TRACE_IRQFLAGS_SUPPORT
201 depends on STACKTRACE_SUPPORT
202 default y
203
204menuconfig FTRACE
205 bool "Tracers"
206 depends on TRACING_SUPPORT
207 default y if DEBUG_KERNEL
208 help
209 Enable the kernel tracing infrastructure.
210
211if FTRACE
212
213config TRACEFS_AUTOMOUNT_DEPRECATED
214 bool "Automount tracefs on debugfs [DEPRECATED]"
215 depends on TRACING
216 default y
217 help
218 The tracing interface was moved from /sys/kernel/debug/tracing
219 to /sys/kernel/tracing in 2015, but the tracing file system
220 was still automounted in /sys/kernel/debug for backward
221 compatibility with tooling.
222
223 The new interface has been around for more than 10 years and
224 the old debug mount will soon be removed.
225
226config BOOTTIME_TRACING
227 bool "Boot-time Tracing support"
228 depends on TRACING
229 select BOOT_CONFIG
230 help
231 Enable developer to setup ftrace subsystem via supplemental
232 kernel cmdline at boot time for debugging (tracing) driver
233 initialization and boot process.
234
235config FUNCTION_TRACER
236 bool "Kernel Function Tracer"
237 depends on HAVE_FUNCTION_TRACER
238 select KALLSYMS
239 select GENERIC_TRACER
240 select CONTEXT_SWITCH_TRACER
241 select GLOB
242 select NEED_TASKS_RCU
243 select TASKS_RUDE_RCU
244 help
245 Enable the kernel to trace every kernel function. This is done
246 by using a compiler feature to insert a small, 5-byte No-Operation
247 instruction at the beginning of every kernel function, which NOP
248 sequence is then dynamically patched into a tracer call when
249 tracing is enabled by the administrator. If it's runtime disabled
250 (the bootup default), then the overhead of the instructions is very
251 small and not measurable even in micro-benchmarks (at least on
252 x86, but may have impact on other architectures).
253
254config FUNCTION_GRAPH_TRACER
255 bool "Kernel Function Graph Tracer"
256 depends on HAVE_FUNCTION_GRAPH_TRACER
257 depends on FUNCTION_TRACER
258 depends on !X86_32 || !CC_OPTIMIZE_FOR_SIZE
259 default y
260 help
261 Enable the kernel to trace a function at both its return
262 and its entry.
263 Its first purpose is to trace the duration of functions and
264 draw a call graph for each thread with some information like
265 the return value. This is done by setting the current return
266 address on the current task structure into a stack of calls.
267
268config FUNCTION_GRAPH_RETVAL
269 bool "Kernel Function Graph Return Value"
270 depends on HAVE_FUNCTION_GRAPH_FREGS
271 depends on FUNCTION_GRAPH_TRACER
272 default n
273 help
274 Support recording and printing the function return value when
275 using function graph tracer. It can be helpful to locate functions
276 that return errors. This feature is off by default, and you can
277 enable it via the trace option funcgraph-retval.
278 See Documentation/trace/ftrace.rst
279
280config FUNCTION_GRAPH_RETADDR
281 bool "Kernel Function Graph Return Address"
282 depends on FUNCTION_GRAPH_TRACER
283 default n
284 help
285 Support recording and printing the function return address when
286 using function graph tracer. It can be helpful to locate code line that
287 the function is called. This feature is off by default, and you can
288 enable it via the trace option funcgraph-retaddr.
289
290config FUNCTION_TRACE_ARGS
291 bool
292 depends on PROBE_EVENTS_BTF_ARGS
293 default y
294 help
295 If supported with function argument access API and BTF, then
296 the function tracer and function graph tracer will support printing
297 of function arguments. This feature is off by default, and can be
298 enabled via the trace option func-args (for the function tracer) and
299 funcgraph-args (for the function graph tracer)
300
301config DYNAMIC_FTRACE
302 bool
303 depends on FUNCTION_TRACER
304 depends on HAVE_DYNAMIC_FTRACE
305 default y
306 help
307 This option will modify all the calls to function tracing
308 dynamically (will patch them out of the binary image and
309 replace them with a No-Op instruction) on boot up. During
310 compile time, a table is made of all the locations that ftrace
311 can function trace, and this table is linked into the kernel
312 image. When this is enabled, functions can be individually
313 enabled, and the functions not enabled will not affect
314 performance of the system.
315
316 See the files in /sys/kernel/tracing:
317 available_filter_functions
318 set_ftrace_filter
319 set_ftrace_notrace
320
321 This way a CONFIG_FUNCTION_TRACER kernel is slightly larger, but
322 otherwise has native performance as long as no tracing is active.
323
324config DYNAMIC_FTRACE_WITH_REGS
325 def_bool y
326 depends on DYNAMIC_FTRACE
327 depends on HAVE_DYNAMIC_FTRACE_WITH_REGS
328
329config DYNAMIC_FTRACE_WITH_DIRECT_CALLS
330 def_bool y
331 depends on DYNAMIC_FTRACE_WITH_REGS || DYNAMIC_FTRACE_WITH_ARGS
332 depends on HAVE_DYNAMIC_FTRACE_WITH_DIRECT_CALLS
333
334config DYNAMIC_FTRACE_WITH_CALL_OPS
335 def_bool y
336 depends on HAVE_DYNAMIC_FTRACE_WITH_CALL_OPS
337
338config DYNAMIC_FTRACE_WITH_ARGS
339 def_bool y
340 depends on DYNAMIC_FTRACE
341 depends on HAVE_DYNAMIC_FTRACE_WITH_ARGS
342
343config DYNAMIC_FTRACE_WITH_JMP
344 def_bool y
345 depends on DYNAMIC_FTRACE
346 depends on DYNAMIC_FTRACE_WITH_DIRECT_CALLS
347 depends on HAVE_DYNAMIC_FTRACE_WITH_JMP
348
349config FUNCTION_SELF_TRACING
350 bool "Function trace tracing code"
351 depends on FUNCTION_TRACER
352 help
353 Normally all the tracing code is set to notrace, where the function
354 tracer will ignore all the tracing functions. Sometimes it is useful
355 for debugging to trace some of the tracing infratructure itself.
356 Enable this to allow some of the tracing infrastructure to be traced
357 by the function tracer. Note, this will likely add noise to function
358 tracing if events and other tracing features are enabled along with
359 function tracing.
360
361 If unsure, say N.
362
363config FPROBE
364 bool "Kernel Function Probe (fprobe)"
365 depends on HAVE_FUNCTION_GRAPH_FREGS && HAVE_FTRACE_GRAPH_FUNC
366 depends on DYNAMIC_FTRACE_WITH_ARGS
367 select FUNCTION_GRAPH_TRACER
368 default n
369 help
370 This option enables kernel function probe (fprobe) based on ftrace.
371 The fprobe is similar to kprobes, but probes only for kernel function
372 entries and exits. This also can probe multiple functions by one
373 fprobe.
374
375 If unsure, say N.
376
377config FUNCTION_PROFILER
378 bool "Kernel function profiler"
379 depends on FUNCTION_TRACER
380 default n
381 help
382 This option enables the kernel function profiler. A file is created
383 in debugfs called function_profile_enabled which defaults to zero.
384 When a 1 is echoed into this file profiling begins, and when a
385 zero is entered, profiling stops. A "functions" file is created in
386 the trace_stat directory; this file shows the list of functions that
387 have been hit and their counters.
388
389 If in doubt, say N.
390
391config STACK_TRACER
392 bool "Trace max stack"
393 depends on HAVE_FUNCTION_TRACER
394 select FUNCTION_TRACER
395 select STACKTRACE
396 select KALLSYMS
397 help
398 This special tracer records the maximum stack footprint of the
399 kernel and displays it in /sys/kernel/tracing/stack_trace.
400
401 This tracer works by hooking into every function call that the
402 kernel executes, and keeping a maximum stack depth value and
403 stack-trace saved. If this is configured with DYNAMIC_FTRACE
404 then it will not have any overhead while the stack tracer
405 is disabled.
406
407 To enable the stack tracer on bootup, pass in 'stacktrace'
408 on the kernel command line.
409
410 The stack tracer can also be enabled or disabled via the
411 sysctl kernel.stack_tracer_enabled
412
413 Say N if unsure.
414
415config TRACE_PREEMPT_TOGGLE
416 bool
417 help
418 Enables hooks which will be called when preemption is first disabled,
419 and last enabled.
420
421config IRQSOFF_TRACER
422 bool "Interrupts-off Latency Tracer"
423 default n
424 depends on TRACE_IRQFLAGS_SUPPORT
425 select TRACE_IRQFLAGS
426 select GENERIC_TRACER
427 select TRACER_MAX_TRACE
428 select RING_BUFFER_ALLOW_SWAP
429 select TRACER_SNAPSHOT_PER_CPU_SWAP
430 help
431 This option measures the time spent in irqs-off critical
432 sections, with microsecond accuracy.
433
434 The default measurement method is a maximum search, which is
435 disabled by default and can be runtime (re-)started
436 via:
437
438 echo 0 > /sys/kernel/tracing/tracing_max_latency
439
440 (Note that kernel size and overhead increase with this option
441 enabled. This option and the preempt-off timing option can be
442 used together or separately.)
443
444config PREEMPT_TRACER
445 bool "Preemption-off Latency Tracer"
446 default n
447 depends on PREEMPTION
448 select GENERIC_TRACER
449 select TRACER_MAX_TRACE
450 select RING_BUFFER_ALLOW_SWAP
451 select TRACER_SNAPSHOT_PER_CPU_SWAP
452 select TRACE_PREEMPT_TOGGLE
453 help
454 This option measures the time spent in preemption-off critical
455 sections, with microsecond accuracy.
456
457 The default measurement method is a maximum search, which is
458 disabled by default and can be runtime (re-)started
459 via:
460
461 echo 0 > /sys/kernel/tracing/tracing_max_latency
462
463 (Note that kernel size and overhead increase with this option
464 enabled. This option and the irqs-off timing option can be
465 used together or separately.)
466
467config SCHED_TRACER
468 bool "Scheduling Latency Tracer"
469 select GENERIC_TRACER
470 select CONTEXT_SWITCH_TRACER
471 select TRACER_MAX_TRACE
472 help
473 This tracer tracks the latency of the highest priority task
474 to be scheduled in, starting from the point it has woken up.
475
476config HWLAT_TRACER
477 bool "Tracer to detect hardware latencies (like SMIs)"
478 select GENERIC_TRACER
479 select TRACER_MAX_TRACE
480 help
481 This tracer, when enabled will create one or more kernel threads,
482 depending on what the cpumask file is set to, which each thread
483 spinning in a loop looking for interruptions caused by
484 something other than the kernel. For example, if a
485 System Management Interrupt (SMI) takes a noticeable amount of
486 time, this tracer will detect it. This is useful for testing
487 if a system is reliable for Real Time tasks.
488
489 Some files are created in the tracing directory when this
490 is enabled:
491
492 hwlat_detector/width - time in usecs for how long to spin for
493 hwlat_detector/window - time in usecs between the start of each
494 iteration
495
496 A kernel thread is created that will spin with interrupts disabled
497 for "width" microseconds in every "window" cycle. It will not spin
498 for "window - width" microseconds, where the system can
499 continue to operate.
500
501 The output will appear in the trace and trace_pipe files.
502
503 When the tracer is not running, it has no affect on the system,
504 but when it is running, it can cause the system to be
505 periodically non responsive. Do not run this tracer on a
506 production system.
507
508 To enable this tracer, echo in "hwlat" into the current_tracer
509 file. Every time a latency is greater than tracing_thresh, it will
510 be recorded into the ring buffer.
511
512config OSNOISE_TRACER
513 bool "OS Noise tracer"
514 select GENERIC_TRACER
515 select TRACER_MAX_TRACE
516 help
517 In the context of high-performance computing (HPC), the Operating
518 System Noise (osnoise) refers to the interference experienced by an
519 application due to activities inside the operating system. In the
520 context of Linux, NMIs, IRQs, SoftIRQs, and any other system thread
521 can cause noise to the system. Moreover, hardware-related jobs can
522 also cause noise, for example, via SMIs.
523
524 The osnoise tracer leverages the hwlat_detector by running a similar
525 loop with preemption, SoftIRQs and IRQs enabled, thus allowing all
526 the sources of osnoise during its execution. The osnoise tracer takes
527 note of the entry and exit point of any source of interferences,
528 increasing a per-cpu interference counter. It saves an interference
529 counter for each source of interference. The interference counter for
530 NMI, IRQs, SoftIRQs, and threads is increased anytime the tool
531 observes these interferences' entry events. When a noise happens
532 without any interference from the operating system level, the
533 hardware noise counter increases, pointing to a hardware-related
534 noise. In this way, osnoise can account for any source of
535 interference. At the end of the period, the osnoise tracer prints
536 the sum of all noise, the max single noise, the percentage of CPU
537 available for the thread, and the counters for the noise sources.
538
539 In addition to the tracer, a set of tracepoints were added to
540 facilitate the identification of the osnoise source.
541
542 The output will appear in the trace and trace_pipe files.
543
544 To enable this tracer, echo in "osnoise" into the current_tracer
545 file.
546
547config TIMERLAT_TRACER
548 bool "Timerlat tracer"
549 select OSNOISE_TRACER
550 select GENERIC_TRACER
551 help
552 The timerlat tracer aims to help the preemptive kernel developers
553 to find sources of wakeup latencies of real-time threads.
554
555 The tracer creates a per-cpu kernel thread with real-time priority.
556 The tracer thread sets a periodic timer to wakeup itself, and goes
557 to sleep waiting for the timer to fire. At the wakeup, the thread
558 then computes a wakeup latency value as the difference between
559 the current time and the absolute time that the timer was set
560 to expire.
561
562 The tracer prints two lines at every activation. The first is the
563 timer latency observed at the hardirq context before the
564 activation of the thread. The second is the timer latency observed
565 by the thread, which is the same level that cyclictest reports. The
566 ACTIVATION ID field serves to relate the irq execution to its
567 respective thread execution.
568
569 The tracer is build on top of osnoise tracer, and the osnoise:
570 events can be used to trace the source of interference from NMI,
571 IRQs and other threads. It also enables the capture of the
572 stacktrace at the IRQ context, which helps to identify the code
573 path that can cause thread delay.
574
575config MMIOTRACE
576 bool "Memory mapped IO tracing"
577 depends on HAVE_MMIOTRACE_SUPPORT && PCI
578 select GENERIC_TRACER
579 help
580 Mmiotrace traces Memory Mapped I/O access and is meant for
581 debugging and reverse engineering. It is called from the ioremap
582 implementation and works via page faults. Tracing is disabled by
583 default and can be enabled at run-time.
584
585 See Documentation/trace/mmiotrace.rst.
586 If you are not helping to develop drivers, say N.
587
588config ENABLE_DEFAULT_TRACERS
589 bool "Trace process context switches and events"
590 depends on !GENERIC_TRACER
591 select TRACING
592 help
593 This tracer hooks to various trace points in the kernel,
594 allowing the user to pick and choose which trace point they
595 want to trace. It also includes the sched_switch tracer plugin.
596
597config FTRACE_SYSCALLS
598 bool "Trace syscalls"
599 depends on HAVE_SYSCALL_TRACEPOINTS
600 select GENERIC_TRACER
601 select KALLSYMS
602 help
603 Basic tracer to catch the syscall entry and exit events.
604
605config TRACE_SYSCALL_BUF_SIZE_DEFAULT
606 int "System call user read max size"
607 range 0 165
608 default 63
609 depends on FTRACE_SYSCALLS
610 help
611 Some system call trace events will record the data from a user
612 space address that one of the parameters point to. The amount of
613 data per event is limited. That limit is set by this config and
614 this config also affects how much user space data perf can read.
615
616 For a tracing instance, this size may be changed by writing into
617 its syscall_user_buf_size file.
618
619config TRACER_SNAPSHOT
620 bool "Create a snapshot trace buffer"
621 help
622 Allow tracing users to take snapshot of the current buffer using the
623 ftrace interface, e.g.:
624
625 echo 1 > /sys/kernel/tracing/snapshot
626 cat snapshot
627
628 Note, the latency tracers select this option. To disable it,
629 all the latency tracers need to be disabled.
630
631config TRACER_SNAPSHOT_PER_CPU_SWAP
632 bool "Allow snapshot to swap per CPU"
633 depends on TRACER_SNAPSHOT
634 select RING_BUFFER_ALLOW_SWAP
635 help
636 Allow doing a snapshot of a single CPU buffer instead of a
637 full swap (all buffers). If this is set, then the following is
638 allowed:
639
640 echo 1 > /sys/kernel/tracing/per_cpu/cpu2/snapshot
641
642 After which, only the tracing buffer for CPU 2 was swapped with
643 the main tracing buffer, and the other CPU buffers remain the same.
644
645 When this is enabled, this adds a little more overhead to the
646 trace recording, as it needs to add some checks to synchronize
647 recording with swaps. But this does not affect the performance
648 of the overall system. This is enabled by default when the preempt
649 or irq latency tracers are enabled, as those need to swap as well
650 and already adds the overhead (plus a lot more).
651
652config TRACE_BRANCH_PROFILING
653 bool
654 select GENERIC_TRACER
655
656choice
657 prompt "Branch Profiling"
658 default BRANCH_PROFILE_NONE
659 help
660 The branch profiling is a software profiler. It will add hooks
661 into the C conditionals to test which path a branch takes.
662
663 The likely/unlikely profiler only looks at the conditions that
664 are annotated with a likely or unlikely macro.
665
666 The "all branch" profiler will profile every if-statement in the
667 kernel. This profiler will also enable the likely/unlikely
668 profiler.
669
670 Either of the above profilers adds a bit of overhead to the system.
671 If unsure, choose "No branch profiling".
672
673config BRANCH_PROFILE_NONE
674 bool "No branch profiling"
675 help
676 No branch profiling. Branch profiling adds a bit of overhead.
677 Only enable it if you want to analyse the branching behavior.
678 Otherwise keep it disabled.
679
680config PROFILE_ANNOTATED_BRANCHES
681 bool "Trace likely/unlikely profiler"
682 select TRACE_BRANCH_PROFILING
683 help
684 This tracer profiles all likely and unlikely macros
685 in the kernel. It will display the results in:
686
687 /sys/kernel/tracing/trace_stat/branch_annotated
688
689 Note: this will add a significant overhead; only turn this
690 on if you need to profile the system's use of these macros.
691
692config PROFILE_ALL_BRANCHES
693 bool "Profile all if conditionals" if !FORTIFY_SOURCE
694 select TRACE_BRANCH_PROFILING
695 help
696 This tracer profiles all branch conditions. Every if ()
697 taken in the kernel is recorded whether it hit or miss.
698 The results will be displayed in:
699
700 /sys/kernel/tracing/trace_stat/branch_all
701
702 This option also enables the likely/unlikely profiler.
703
704 This configuration, when enabled, will impose a great overhead
705 on the system. This should only be enabled when the system
706 is to be analyzed in much detail.
707endchoice
708
709config TRACING_BRANCHES
710 bool
711 help
712 Selected by tracers that will trace the likely and unlikely
713 conditions. This prevents the tracers themselves from being
714 profiled. Profiling the tracing infrastructure can only happen
715 when the likelys and unlikelys are not being traced.
716
717config BRANCH_TRACER
718 bool "Trace likely/unlikely instances"
719 depends on TRACE_BRANCH_PROFILING
720 select TRACING_BRANCHES
721 help
722 This traces the events of likely and unlikely condition
723 calls in the kernel. The difference between this and the
724 "Trace likely/unlikely profiler" is that this is not a
725 histogram of the callers, but actually places the calling
726 events into a running trace buffer to see when and where the
727 events happened, as well as their results.
728
729 Say N if unsure.
730
731config BLK_DEV_IO_TRACE
732 bool "Support for tracing block IO actions"
733 depends on SYSFS
734 depends on BLOCK
735 select RELAY
736 select DEBUG_FS
737 select TRACEPOINTS
738 select GENERIC_TRACER
739 select STACKTRACE
740 help
741 Say Y here if you want to be able to trace the block layer actions
742 on a given queue. Tracing allows you to see any traffic happening
743 on a block device queue. For more information (and the userspace
744 support tools needed), fetch the blktrace tools from:
745
746 git://git.kernel.dk/blktrace.git
747
748 Tracing also is possible using the ftrace interface, e.g.:
749
750 echo 1 > /sys/block/sda/sda1/trace/enable
751 echo blk > /sys/kernel/tracing/current_tracer
752 cat /sys/kernel/tracing/trace_pipe
753
754 If unsure, say N.
755
756config FPROBE_EVENTS
757 depends on FPROBE
758 depends on HAVE_REGS_AND_STACK_ACCESS_API
759 bool "Enable fprobe-based dynamic events"
760 select TRACING
761 select PROBE_EVENTS
762 select DYNAMIC_EVENTS
763 default y
764 help
765 This allows user to add tracing events on the function entry and
766 exit via ftrace interface. The syntax is same as the kprobe events
767 and the kprobe events on function entry and exit will be
768 transparently converted to this fprobe events.
769
770config PROBE_EVENTS_BTF_ARGS
771 depends on HAVE_FUNCTION_ARG_ACCESS_API
772 depends on FPROBE_EVENTS || KPROBE_EVENTS
773 depends on DEBUG_INFO_BTF && BPF_SYSCALL
774 bool "Support BTF function arguments for probe events"
775 default y
776 help
777 The user can specify the arguments of the probe event using the names
778 of the arguments of the probed function, when the probe location is a
779 kernel function entry or a tracepoint.
780 This is available only if BTF (BPF Type Format) support is enabled.
781
782config KPROBE_EVENTS
783 depends on KPROBES
784 depends on HAVE_REGS_AND_STACK_ACCESS_API
785 bool "Enable kprobes-based dynamic events"
786 select TRACING
787 select PROBE_EVENTS
788 select DYNAMIC_EVENTS
789 default y
790 help
791 This allows the user to add tracing events (similar to tracepoints)
792 on the fly via the ftrace interface. See
793 Documentation/trace/kprobetrace.rst for more details.
794
795 Those events can be inserted wherever kprobes can probe, and record
796 various register and memory values.
797
798 This option is also required by perf-probe subcommand of perf tools.
799 If you want to use perf tools, this option is strongly recommended.
800
801config KPROBE_EVENTS_ON_NOTRACE
802 bool "Do NOT protect notrace function from kprobe events"
803 depends on KPROBE_EVENTS
804 depends on DYNAMIC_FTRACE
805 default n
806 help
807 This is only for the developers who want to debug ftrace itself
808 using kprobe events.
809
810 If kprobes can use ftrace instead of breakpoint, ftrace related
811 functions are protected from kprobe-events to prevent an infinite
812 recursion or any unexpected execution path which leads to a kernel
813 crash.
814
815 This option disables such protection and allows you to put kprobe
816 events on ftrace functions for debugging ftrace by itself.
817 Note that this might let you shoot yourself in the foot.
818
819 If unsure, say N.
820
821config UPROBE_EVENTS
822 bool "Enable uprobes-based dynamic events"
823 depends on ARCH_SUPPORTS_UPROBES
824 depends on MMU
825 depends on PERF_EVENTS
826 select UPROBES
827 select PROBE_EVENTS
828 select DYNAMIC_EVENTS
829 select TRACING
830 default y
831 help
832 This allows the user to add tracing events on top of userspace
833 dynamic events (similar to tracepoints) on the fly via the trace
834 events interface. Those events can be inserted wherever uprobes
835 can probe, and record various registers.
836 This option is required if you plan to use perf-probe subcommand
837 of perf tools on user space applications.
838
839config EPROBE_EVENTS
840 bool "Enable event-based dynamic events"
841 depends on TRACING
842 depends on HAVE_REGS_AND_STACK_ACCESS_API
843 select PROBE_EVENTS
844 select DYNAMIC_EVENTS
845 default y
846 help
847 Eprobes are dynamic events that can be placed on other existing
848 events. It can be used to limit what fields are recorded in
849 an event or even dereference a field of an event. It can
850 convert the type of an event field. For example, turn an
851 address into a string.
852
853config BPF_EVENTS
854 depends on BPF_SYSCALL
855 depends on (KPROBE_EVENTS || UPROBE_EVENTS) && PERF_EVENTS
856 bool
857 default y
858 help
859 This allows the user to attach BPF programs to kprobe, uprobe, and
860 tracepoint events.
861
862config DYNAMIC_EVENTS
863 def_bool n
864
865config PROBE_EVENTS
866 def_bool n
867
868config BPF_KPROBE_OVERRIDE
869 bool "Enable BPF programs to override a kprobed function"
870 depends on BPF_EVENTS
871 depends on FUNCTION_ERROR_INJECTION
872 default n
873 help
874 Allows BPF to override the execution of a probed function and
875 set a different return value. This is used for error injection.
876
877config FTRACE_MCOUNT_USE_PATCHABLE_FUNCTION_ENTRY
878 bool
879 depends on DYNAMIC_FTRACE
880
881config FTRACE_MCOUNT_USE_CC
882 def_bool y
883 depends on $(cc-option,-mrecord-mcount)
884 depends on !FTRACE_MCOUNT_USE_PATCHABLE_FUNCTION_ENTRY
885 depends on DYNAMIC_FTRACE
886
887config FTRACE_MCOUNT_USE_OBJTOOL
888 def_bool y
889 depends on HAVE_OBJTOOL_MCOUNT
890 depends on !FTRACE_MCOUNT_USE_PATCHABLE_FUNCTION_ENTRY
891 depends on !FTRACE_MCOUNT_USE_CC
892 depends on DYNAMIC_FTRACE
893 select OBJTOOL
894
895config FTRACE_MCOUNT_USE_RECORDMCOUNT
896 def_bool y
897 depends on !FTRACE_MCOUNT_USE_PATCHABLE_FUNCTION_ENTRY
898 depends on !FTRACE_MCOUNT_USE_CC
899 depends on !FTRACE_MCOUNT_USE_OBJTOOL
900 depends on DYNAMIC_FTRACE
901
902config TRACING_MAP
903 bool
904 depends on ARCH_HAVE_NMI_SAFE_CMPXCHG
905 help
906 tracing_map is a special-purpose lock-free map for tracing,
907 separated out as a stand-alone facility in order to allow it
908 to be shared between multiple tracers. It isn't meant to be
909 generally used outside of that context, and is normally
910 selected by tracers that use it.
911
912config SYNTH_EVENTS
913 bool "Synthetic trace events"
914 select TRACING
915 select DYNAMIC_EVENTS
916 default n
917 help
918 Synthetic events are user-defined trace events that can be
919 used to combine data from other trace events or in fact any
920 data source. Synthetic events can be generated indirectly
921 via the trace() action of histogram triggers or directly
922 by way of an in-kernel API.
923
924 See Documentation/trace/events.rst or
925 Documentation/trace/histogram.rst for details and examples.
926
927 If in doubt, say N.
928
929config USER_EVENTS
930 bool "User trace events"
931 select TRACING
932 select DYNAMIC_EVENTS
933 help
934 User trace events are user-defined trace events that
935 can be used like an existing kernel trace event. User trace
936 events are generated by writing to a tracefs file. User
937 processes can determine if their tracing events should be
938 generated by registering a value and bit with the kernel
939 that reflects when it is enabled or not.
940
941 See Documentation/trace/user_events.rst.
942 If in doubt, say N.
943
944config HIST_TRIGGERS
945 bool "Histogram triggers"
946 depends on ARCH_HAVE_NMI_SAFE_CMPXCHG
947 select TRACING_MAP
948 select TRACING
949 select DYNAMIC_EVENTS
950 select SYNTH_EVENTS
951 default n
952 help
953 Hist triggers allow one or more arbitrary trace event fields
954 to be aggregated into hash tables and dumped to stdout by
955 reading a debugfs/tracefs file. They're useful for
956 gathering quick and dirty (though precise) summaries of
957 event activity as an initial guide for further investigation
958 using more advanced tools.
959
960 Inter-event tracing of quantities such as latencies is also
961 supported using hist triggers under this option.
962
963 See Documentation/trace/histogram.rst.
964 If in doubt, say N.
965
966config TRACE_EVENT_INJECT
967 bool "Trace event injection"
968 depends on TRACING
969 help
970 Allow user-space to inject a specific trace event into the ring
971 buffer. This is mainly used for testing purpose.
972
973 If unsure, say N.
974
975config TRACEPOINT_BENCHMARK
976 bool "Add tracepoint that benchmarks tracepoints"
977 help
978 This option creates the tracepoint "benchmark:benchmark_event".
979 When the tracepoint is enabled, it kicks off a kernel thread that
980 goes into an infinite loop (calling cond_resched() to let other tasks
981 run), and calls the tracepoint. Each iteration will record the time
982 it took to write to the tracepoint and the next iteration that
983 data will be passed to the tracepoint itself. That is, the tracepoint
984 will report the time it took to do the previous tracepoint.
985 The string written to the tracepoint is a static string of 128 bytes
986 to keep the time the same. The initial string is simply a write of
987 "START". The second string records the cold cache time of the first
988 write which is not added to the rest of the calculations.
989
990 As it is a tight loop, it benchmarks as hot cache. That's fine because
991 we care most about hot paths that are probably in cache already.
992
993 An example of the output:
994
995 START
996 first=3672 [COLD CACHED]
997 last=632 first=3672 max=632 min=632 avg=316 std=446 std^2=199712
998 last=278 first=3672 max=632 min=278 avg=303 std=316 std^2=100337
999 last=277 first=3672 max=632 min=277 avg=296 std=258 std^2=67064
1000 last=273 first=3672 max=632 min=273 avg=292 std=224 std^2=50411
1001 last=273 first=3672 max=632 min=273 avg=288 std=200 std^2=40389
1002 last=281 first=3672 max=632 min=273 avg=287 std=183 std^2=33666
1003
1004
1005config RING_BUFFER_BENCHMARK
1006 tristate "Ring buffer benchmark stress tester"
1007 depends on RING_BUFFER
1008 help
1009 This option creates a test to stress the ring buffer and benchmark it.
1010 It creates its own ring buffer such that it will not interfere with
1011 any other users of the ring buffer (such as ftrace). It then creates
1012 a producer and consumer that will run for 10 seconds and sleep for
1013 10 seconds. Each interval it will print out the number of events
1014 it recorded and give a rough estimate of how long each iteration took.
1015
1016 It does not disable interrupts or raise its priority, so it may be
1017 affected by processes that are running.
1018
1019 If unsure, say N.
1020
1021config TRACE_EVAL_MAP_FILE
1022 bool "Show eval mappings for trace events"
1023 depends on TRACING
1024 help
1025 The "print fmt" of the trace events will show the enum/sizeof names
1026 instead of their values. This can cause problems for user space tools
1027 that use this string to parse the raw data as user space does not know
1028 how to convert the string to its value.
1029
1030 To fix this, there's a special macro in the kernel that can be used
1031 to convert an enum/sizeof into its value. If this macro is used, then
1032 the print fmt strings will be converted to their values.
1033
1034 If something does not get converted properly, this option can be
1035 used to show what enums/sizeof the kernel tried to convert.
1036
1037 This option is for debugging the conversions. A file is created
1038 in the tracing directory called "eval_map" that will show the
1039 names matched with their values and what trace event system they
1040 belong too.
1041
1042 Normally, the mapping of the strings to values will be freed after
1043 boot up or module load. With this option, they will not be freed, as
1044 they are needed for the "eval_map" file. Enabling this option will
1045 increase the memory footprint of the running kernel.
1046
1047 If unsure, say N.
1048
1049config FTRACE_RECORD_RECURSION
1050 bool "Record functions that recurse in function tracing"
1051 depends on FUNCTION_TRACER
1052 help
1053 All callbacks that attach to the function tracing have some sort
1054 of protection against recursion. Even though the protection exists,
1055 it adds overhead. This option will create a file in the tracefs
1056 file system called "recursed_functions" that will list the functions
1057 that triggered a recursion.
1058
1059 This will add more overhead to cases that have recursion.
1060
1061 If unsure, say N
1062
1063config FTRACE_RECORD_RECURSION_SIZE
1064 int "Max number of recursed functions to record"
1065 default 128
1066 depends on FTRACE_RECORD_RECURSION
1067 help
1068 This defines the limit of number of functions that can be
1069 listed in the "recursed_functions" file, that lists all
1070 the functions that caused a recursion to happen.
1071 This file can be reset, but the limit can not change in
1072 size at runtime.
1073
1074config FTRACE_VALIDATE_RCU_IS_WATCHING
1075 bool "Validate RCU is on during ftrace execution"
1076 depends on FUNCTION_TRACER
1077 depends on ARCH_WANTS_NO_INSTR
1078 help
1079 All callbacks that attach to the function tracing have some sort of
1080 protection against recursion. This option is only to verify that
1081 ftrace (and other users of ftrace_test_recursion_trylock()) are not
1082 called outside of RCU, as if they are, it can cause a race. But it
1083 also has a noticeable overhead when enabled.
1084
1085 If unsure, say N
1086
1087config RING_BUFFER_RECORD_RECURSION
1088 bool "Record functions that recurse in the ring buffer"
1089 depends on FTRACE_RECORD_RECURSION
1090 # default y, because it is coupled with FTRACE_RECORD_RECURSION
1091 default y
1092 help
1093 The ring buffer has its own internal recursion. Although when
1094 recursion happens it won't cause harm because of the protection,
1095 but it does cause unwanted overhead. Enabling this option will
1096 place where recursion was detected into the ftrace "recursed_functions"
1097 file.
1098
1099 This will add more overhead to cases that have recursion.
1100
1101config GCOV_PROFILE_FTRACE
1102 bool "Enable GCOV profiling on ftrace subsystem"
1103 depends on GCOV_KERNEL
1104 help
1105 Enable GCOV profiling on ftrace subsystem for checking
1106 which functions/lines are tested.
1107
1108 If unsure, say N.
1109
1110 Note that on a kernel compiled with this config, ftrace will
1111 run significantly slower.
1112
1113config FTRACE_SELFTEST
1114 bool
1115
1116config FTRACE_STARTUP_TEST
1117 bool "Perform a startup test on ftrace"
1118 depends on GENERIC_TRACER
1119 select FTRACE_SELFTEST
1120 help
1121 This option performs a series of startup tests on ftrace. On bootup
1122 a series of tests are made to verify that the tracer is
1123 functioning properly. It will do tests on all the configured
1124 tracers of ftrace.
1125
1126config EVENT_TRACE_STARTUP_TEST
1127 bool "Run selftest on trace events"
1128 depends on FTRACE_STARTUP_TEST
1129 default y
1130 help
1131 This option performs a test on all trace events in the system.
1132 It basically just enables each event and runs some code that
1133 will trigger events (not necessarily the event it enables)
1134 This may take some time run as there are a lot of events.
1135
1136config EVENT_TRACE_TEST_SYSCALLS
1137 bool "Run selftest on syscall events"
1138 depends on EVENT_TRACE_STARTUP_TEST
1139 help
1140 This option will also enable testing every syscall event.
1141 It only enables the event and disables it and runs various loads
1142 with the event enabled. This adds a bit more time for kernel boot
1143 up since it runs this on every system call defined.
1144
1145 TBD - enable a way to actually call the syscalls as we test their
1146 events
1147
1148config FTRACE_SORT_STARTUP_TEST
1149 bool "Verify compile time sorting of ftrace functions"
1150 depends on DYNAMIC_FTRACE
1151 depends on BUILDTIME_MCOUNT_SORT
1152 help
1153 Sorting of the mcount_loc sections that is used to find the
1154 where the ftrace knows where to patch functions for tracing
1155 and other callbacks is done at compile time. But if the sort
1156 is not done correctly, it will cause non-deterministic failures.
1157 When this is set, the sorted sections will be verified that they
1158 are in deed sorted and will warn if they are not.
1159
1160 If unsure, say N
1161
1162config RING_BUFFER_STARTUP_TEST
1163 bool "Ring buffer startup self test"
1164 depends on RING_BUFFER
1165 help
1166 Run a simple self test on the ring buffer on boot up. Late in the
1167 kernel boot sequence, the test will start that kicks off
1168 a thread per cpu. Each thread will write various size events
1169 into the ring buffer. Another thread is created to send IPIs
1170 to each of the threads, where the IPI handler will also write
1171 to the ring buffer, to test/stress the nesting ability.
1172 If any anomalies are discovered, a warning will be displayed
1173 and all ring buffers will be disabled.
1174
1175 The test runs for 10 seconds. This will slow your boot time
1176 by at least 10 more seconds.
1177
1178 At the end of the test, statistics and more checks are done.
1179 It will output the stats of each per cpu buffer: What
1180 was written, the sizes, what was read, what was lost, and
1181 other similar details.
1182
1183 If unsure, say N
1184
1185config RING_BUFFER_VALIDATE_TIME_DELTAS
1186 bool "Verify ring buffer time stamp deltas"
1187 depends on RING_BUFFER
1188 help
1189 This will audit the time stamps on the ring buffer sub
1190 buffer to make sure that all the time deltas for the
1191 events on a sub buffer matches the current time stamp.
1192 This audit is performed for every event that is not
1193 interrupted, or interrupting another event. A check
1194 is also made when traversing sub buffers to make sure
1195 that all the deltas on the previous sub buffer do not
1196 add up to be greater than the current time stamp.
1197
1198 NOTE: This adds significant overhead to recording of events,
1199 and should only be used to test the logic of the ring buffer.
1200 Do not use it on production systems.
1201
1202 Only say Y if you understand what this does, and you
1203 still want it enabled. Otherwise say N
1204
1205config RING_BUFFER_PERSISTENT_INJECT
1206 bool "Enable persistent ring buffer error injection test"
1207 depends on RING_BUFFER
1208 help
1209 This option will have the kernel check if the persistent ring
1210 buffer is named "ptracingtest". and if so, it will corrupt some
1211 of its pages on a kernel panic. This is used to test if the
1212 persistent ring buffer can recover from some of its sub-buffers
1213 being corrupted.
1214 To use this, boot a kernel with a "ptracingtest" persistent
1215 ring buffer, e.g.
1216
1217 reserve_mem=20M:2M:trace trace_instance=ptracingtest@trace panic=1
1218
1219 And after the 1st boot, run the following commands:
1220
1221 cd /sys/kernel/tracing/instances/ptracingtest
1222 echo 1 > events/enable
1223 echo 1 > tracing_on
1224 sleep 3
1225 echo c > /proc/sysrq-trigger
1226
1227 After the panic message, the kernel will reboot and will show
1228 the test results in the console output.
1229
1230 Note that events for the test ring buffer needs to be enabled
1231 prior to crashing the kernel so that the ring buffer has content
1232 that the test will corrupt.
1233 As the test will corrupt events in the "ptracingtest" persistent
1234 ring buffer, it should not be used for any other purpose other
1235 than this test.
1236
1237 If unsure, say N
1238
1239config MMIOTRACE_TEST
1240 tristate "Test module for mmiotrace"
1241 depends on MMIOTRACE && m
1242 help
1243 This is a dumb module for testing mmiotrace. It is very dangerous
1244 as it will write garbage to IO memory starting at a given address.
1245 However, it should be safe to use on e.g. unused portion of VRAM.
1246
1247 Say N, unless you absolutely know what you are doing.
1248
1249config PREEMPTIRQ_DELAY_TEST
1250 tristate "Test module to create a preempt / IRQ disable delay thread to test latency tracers"
1251 depends on m
1252 help
1253 Select this option to build a test module that can help test latency
1254 tracers by executing a preempt or irq disable section with a user
1255 configurable delay. The module busy waits for the duration of the
1256 critical section.
1257
1258 For example, the following invocation generates a burst of three
1259 irq-disabled critical sections for 500us:
1260 modprobe preemptirq_delay_test test_mode=irq delay=500 burst_size=3
1261
1262 What's more, if you want to attach the test on the cpu which the latency
1263 tracer is running on, specify cpu_affinity=cpu_num at the end of the
1264 command.
1265
1266 If unsure, say N
1267
1268config SYNTH_EVENT_GEN_TEST
1269 tristate "Test module for in-kernel synthetic event generation"
1270 depends on SYNTH_EVENTS && m
1271 help
1272 This option creates a test module to check the base
1273 functionality of in-kernel synthetic event definition and
1274 generation.
1275
1276 To test, insert the module, and then check the trace buffer
1277 for the generated sample events.
1278
1279 If unsure, say N.
1280
1281config KPROBE_EVENT_GEN_TEST
1282 tristate "Test module for in-kernel kprobe event generation"
1283 depends on KPROBE_EVENTS && m
1284 help
1285 This option creates a test module to check the base
1286 functionality of in-kernel kprobe event definition.
1287
1288 To test, insert the module, and then check the trace buffer
1289 for the generated kprobe events.
1290
1291 If unsure, say N.
1292
1293config HIST_TRIGGERS_DEBUG
1294 bool "Hist trigger debug support"
1295 depends on HIST_TRIGGERS
1296 help
1297 Add "hist_debug" file for each event, which when read will
1298 dump out a bunch of internal details about the hist triggers
1299 defined on that event.
1300
1301 The hist_debug file serves a couple of purposes:
1302
1303 - Helps developers verify that nothing is broken.
1304
1305 - Provides educational information to support the details
1306 of the hist trigger internals as described by
1307 Documentation/trace/histogram-design.rst.
1308
1309 The hist_debug output only covers the data structures
1310 related to the histogram definitions themselves and doesn't
1311 display the internals of map buckets or variable values of
1312 running histograms.
1313
1314 If unsure, say N.
1315
1316source "kernel/trace/rv/Kconfig"
1317
1318config TRACE_REMOTE
1319 bool
1320
1321config SIMPLE_RING_BUFFER
1322 bool
1323
1324config TRACE_REMOTE_TEST
1325 tristate "Test module for remote tracing"
1326 select TRACE_REMOTE
1327 select SIMPLE_RING_BUFFER
1328 help
1329 This trace remote includes a ring-buffer writer implementation using
1330 "simple_ring_buffer". This is solely intending for testing.
1331
1332endif # FTRACE