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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_RETVAL
35 bool
36
37config HAVE_DYNAMIC_FTRACE
38 bool
39 help
40 See Documentation/trace/ftrace-design.rst
41
42config HAVE_DYNAMIC_FTRACE_WITH_REGS
43 bool
44
45config HAVE_DYNAMIC_FTRACE_WITH_DIRECT_CALLS
46 bool
47
48config HAVE_DYNAMIC_FTRACE_WITH_CALL_OPS
49 bool
50
51config HAVE_DYNAMIC_FTRACE_WITH_ARGS
52 bool
53 help
54 If this is set, then arguments and stack can be found from
55 the ftrace_regs passed into the function callback regs parameter
56 by default, even without setting the REGS flag in the ftrace_ops.
57 This allows for use of ftrace_regs_get_argument() and
58 ftrace_regs_get_stack_pointer().
59
60config HAVE_DYNAMIC_FTRACE_NO_PATCHABLE
61 bool
62 help
63 If the architecture generates __patchable_function_entries sections
64 but does not want them included in the ftrace locations.
65
66config HAVE_FTRACE_MCOUNT_RECORD
67 bool
68 help
69 See Documentation/trace/ftrace-design.rst
70
71config HAVE_SYSCALL_TRACEPOINTS
72 bool
73 help
74 See Documentation/trace/ftrace-design.rst
75
76config HAVE_FENTRY
77 bool
78 help
79 Arch supports the gcc options -pg with -mfentry
80
81config HAVE_NOP_MCOUNT
82 bool
83 help
84 Arch supports the gcc options -pg with -mrecord-mcount and -nop-mcount
85
86config HAVE_OBJTOOL_MCOUNT
87 bool
88 help
89 Arch supports objtool --mcount
90
91config HAVE_OBJTOOL_NOP_MCOUNT
92 bool
93 help
94 Arch supports the objtool options --mcount with --mnop.
95 An architecture can select this if it wants to enable nop'ing
96 of ftrace locations.
97
98config HAVE_C_RECORDMCOUNT
99 bool
100 help
101 C version of recordmcount available?
102
103config HAVE_BUILDTIME_MCOUNT_SORT
104 bool
105 help
106 An architecture selects this if it sorts the mcount_loc section
107 at build time.
108
109config BUILDTIME_MCOUNT_SORT
110 bool
111 default y
112 depends on HAVE_BUILDTIME_MCOUNT_SORT && DYNAMIC_FTRACE
113 help
114 Sort the mcount_loc section at build time.
115
116config TRACER_MAX_TRACE
117 bool
118
119config TRACE_CLOCK
120 bool
121
122config RING_BUFFER
123 bool
124 select TRACE_CLOCK
125 select IRQ_WORK
126
127config EVENT_TRACING
128 select CONTEXT_SWITCH_TRACER
129 select GLOB
130 bool
131
132config CONTEXT_SWITCH_TRACER
133 bool
134
135config RING_BUFFER_ALLOW_SWAP
136 bool
137 help
138 Allow the use of ring_buffer_swap_cpu.
139 Adds a very slight overhead to tracing when enabled.
140
141config PREEMPTIRQ_TRACEPOINTS
142 bool
143 depends on TRACE_PREEMPT_TOGGLE || TRACE_IRQFLAGS
144 select TRACING
145 default y
146 help
147 Create preempt/irq toggle tracepoints if needed, so that other parts
148 of the kernel can use them to generate or add hooks to them.
149
150# All tracer options should select GENERIC_TRACER. For those options that are
151# enabled by all tracers (context switch and event tracer) they select TRACING.
152# This allows those options to appear when no other tracer is selected. But the
153# options do not appear when something else selects it. We need the two options
154# GENERIC_TRACER and TRACING to avoid circular dependencies to accomplish the
155# hiding of the automatic options.
156
157config TRACING
158 bool
159 select RING_BUFFER
160 select STACKTRACE if STACKTRACE_SUPPORT
161 select TRACEPOINTS
162 select NOP_TRACER
163 select BINARY_PRINTF
164 select EVENT_TRACING
165 select TRACE_CLOCK
166 select NEED_TASKS_RCU
167
168config GENERIC_TRACER
169 bool
170 select TRACING
171
172#
173# Minimum requirements an architecture has to meet for us to
174# be able to offer generic tracing facilities:
175#
176config TRACING_SUPPORT
177 bool
178 depends on TRACE_IRQFLAGS_SUPPORT
179 depends on STACKTRACE_SUPPORT
180 default y
181
182menuconfig FTRACE
183 bool "Tracers"
184 depends on TRACING_SUPPORT
185 default y if DEBUG_KERNEL
186 help
187 Enable the kernel tracing infrastructure.
188
189if FTRACE
190
191config BOOTTIME_TRACING
192 bool "Boot-time Tracing support"
193 depends on TRACING
194 select BOOT_CONFIG
195 help
196 Enable developer to setup ftrace subsystem via supplemental
197 kernel cmdline at boot time for debugging (tracing) driver
198 initialization and boot process.
199
200config FUNCTION_TRACER
201 bool "Kernel Function Tracer"
202 depends on HAVE_FUNCTION_TRACER
203 select KALLSYMS
204 select GENERIC_TRACER
205 select CONTEXT_SWITCH_TRACER
206 select GLOB
207 select NEED_TASKS_RCU
208 select TASKS_RUDE_RCU
209 help
210 Enable the kernel to trace every kernel function. This is done
211 by using a compiler feature to insert a small, 5-byte No-Operation
212 instruction at the beginning of every kernel function, which NOP
213 sequence is then dynamically patched into a tracer call when
214 tracing is enabled by the administrator. If it's runtime disabled
215 (the bootup default), then the overhead of the instructions is very
216 small and not measurable even in micro-benchmarks (at least on
217 x86, but may have impact on other architectures).
218
219config FUNCTION_GRAPH_TRACER
220 bool "Kernel Function Graph Tracer"
221 depends on HAVE_FUNCTION_GRAPH_TRACER
222 depends on FUNCTION_TRACER
223 depends on !X86_32 || !CC_OPTIMIZE_FOR_SIZE
224 default y
225 help
226 Enable the kernel to trace a function at both its return
227 and its entry.
228 Its first purpose is to trace the duration of functions and
229 draw a call graph for each thread with some information like
230 the return value. This is done by setting the current return
231 address on the current task structure into a stack of calls.
232
233config FUNCTION_GRAPH_RETVAL
234 bool "Kernel Function Graph Return Value"
235 depends on HAVE_FUNCTION_GRAPH_RETVAL
236 depends on FUNCTION_GRAPH_TRACER
237 default n
238 help
239 Support recording and printing the function return value when
240 using function graph tracer. It can be helpful to locate functions
241 that return errors. This feature is off by default, and you can
242 enable it via the trace option funcgraph-retval.
243 See Documentation/trace/ftrace.rst
244
245config FUNCTION_GRAPH_RETADDR
246 bool "Kernel Function Graph Return Address"
247 depends on FUNCTION_GRAPH_TRACER
248 default n
249 help
250 Support recording and printing the function return address when
251 using function graph tracer. It can be helpful to locate code line that
252 the function is called. This feature is off by default, and you can
253 enable it via the trace option funcgraph-retaddr.
254
255config DYNAMIC_FTRACE
256 bool "enable/disable function tracing dynamically"
257 depends on FUNCTION_TRACER
258 depends on HAVE_DYNAMIC_FTRACE
259 default y
260 help
261 This option will modify all the calls to function tracing
262 dynamically (will patch them out of the binary image and
263 replace them with a No-Op instruction) on boot up. During
264 compile time, a table is made of all the locations that ftrace
265 can function trace, and this table is linked into the kernel
266 image. When this is enabled, functions can be individually
267 enabled, and the functions not enabled will not affect
268 performance of the system.
269
270 See the files in /sys/kernel/tracing:
271 available_filter_functions
272 set_ftrace_filter
273 set_ftrace_notrace
274
275 This way a CONFIG_FUNCTION_TRACER kernel is slightly larger, but
276 otherwise has native performance as long as no tracing is active.
277
278config DYNAMIC_FTRACE_WITH_REGS
279 def_bool y
280 depends on DYNAMIC_FTRACE
281 depends on HAVE_DYNAMIC_FTRACE_WITH_REGS
282
283config DYNAMIC_FTRACE_WITH_DIRECT_CALLS
284 def_bool y
285 depends on DYNAMIC_FTRACE_WITH_REGS || DYNAMIC_FTRACE_WITH_ARGS
286 depends on HAVE_DYNAMIC_FTRACE_WITH_DIRECT_CALLS
287
288config DYNAMIC_FTRACE_WITH_CALL_OPS
289 def_bool y
290 depends on HAVE_DYNAMIC_FTRACE_WITH_CALL_OPS
291
292config DYNAMIC_FTRACE_WITH_ARGS
293 def_bool y
294 depends on DYNAMIC_FTRACE
295 depends on HAVE_DYNAMIC_FTRACE_WITH_ARGS
296
297config FPROBE
298 bool "Kernel Function Probe (fprobe)"
299 depends on FUNCTION_TRACER
300 depends on DYNAMIC_FTRACE_WITH_REGS
301 depends on HAVE_RETHOOK
302 select RETHOOK
303 default n
304 help
305 This option enables kernel function probe (fprobe) based on ftrace.
306 The fprobe is similar to kprobes, but probes only for kernel function
307 entries and exits. This also can probe multiple functions by one
308 fprobe.
309
310 If unsure, say N.
311
312config FUNCTION_PROFILER
313 bool "Kernel function profiler"
314 depends on FUNCTION_TRACER
315 default n
316 help
317 This option enables the kernel function profiler. A file is created
318 in debugfs called function_profile_enabled which defaults to zero.
319 When a 1 is echoed into this file profiling begins, and when a
320 zero is entered, profiling stops. A "functions" file is created in
321 the trace_stat directory; this file shows the list of functions that
322 have been hit and their counters.
323
324 If in doubt, say N.
325
326config STACK_TRACER
327 bool "Trace max stack"
328 depends on HAVE_FUNCTION_TRACER
329 select FUNCTION_TRACER
330 select STACKTRACE
331 select KALLSYMS
332 help
333 This special tracer records the maximum stack footprint of the
334 kernel and displays it in /sys/kernel/tracing/stack_trace.
335
336 This tracer works by hooking into every function call that the
337 kernel executes, and keeping a maximum stack depth value and
338 stack-trace saved. If this is configured with DYNAMIC_FTRACE
339 then it will not have any overhead while the stack tracer
340 is disabled.
341
342 To enable the stack tracer on bootup, pass in 'stacktrace'
343 on the kernel command line.
344
345 The stack tracer can also be enabled or disabled via the
346 sysctl kernel.stack_tracer_enabled
347
348 Say N if unsure.
349
350config TRACE_PREEMPT_TOGGLE
351 bool
352 help
353 Enables hooks which will be called when preemption is first disabled,
354 and last enabled.
355
356config IRQSOFF_TRACER
357 bool "Interrupts-off Latency Tracer"
358 default n
359 depends on TRACE_IRQFLAGS_SUPPORT
360 select TRACE_IRQFLAGS
361 select GENERIC_TRACER
362 select TRACER_MAX_TRACE
363 select RING_BUFFER_ALLOW_SWAP
364 select TRACER_SNAPSHOT
365 select TRACER_SNAPSHOT_PER_CPU_SWAP
366 help
367 This option measures the time spent in irqs-off critical
368 sections, with microsecond accuracy.
369
370 The default measurement method is a maximum search, which is
371 disabled by default and can be runtime (re-)started
372 via:
373
374 echo 0 > /sys/kernel/tracing/tracing_max_latency
375
376 (Note that kernel size and overhead increase with this option
377 enabled. This option and the preempt-off timing option can be
378 used together or separately.)
379
380config PREEMPT_TRACER
381 bool "Preemption-off Latency Tracer"
382 default n
383 depends on PREEMPTION
384 select GENERIC_TRACER
385 select TRACER_MAX_TRACE
386 select RING_BUFFER_ALLOW_SWAP
387 select TRACER_SNAPSHOT
388 select TRACER_SNAPSHOT_PER_CPU_SWAP
389 select TRACE_PREEMPT_TOGGLE
390 help
391 This option measures the time spent in preemption-off critical
392 sections, with microsecond accuracy.
393
394 The default measurement method is a maximum search, which is
395 disabled by default and can be runtime (re-)started
396 via:
397
398 echo 0 > /sys/kernel/tracing/tracing_max_latency
399
400 (Note that kernel size and overhead increase with this option
401 enabled. This option and the irqs-off timing option can be
402 used together or separately.)
403
404config SCHED_TRACER
405 bool "Scheduling Latency Tracer"
406 select GENERIC_TRACER
407 select CONTEXT_SWITCH_TRACER
408 select TRACER_MAX_TRACE
409 select TRACER_SNAPSHOT
410 help
411 This tracer tracks the latency of the highest priority task
412 to be scheduled in, starting from the point it has woken up.
413
414config HWLAT_TRACER
415 bool "Tracer to detect hardware latencies (like SMIs)"
416 select GENERIC_TRACER
417 select TRACER_MAX_TRACE
418 help
419 This tracer, when enabled will create one or more kernel threads,
420 depending on what the cpumask file is set to, which each thread
421 spinning in a loop looking for interruptions caused by
422 something other than the kernel. For example, if a
423 System Management Interrupt (SMI) takes a noticeable amount of
424 time, this tracer will detect it. This is useful for testing
425 if a system is reliable for Real Time tasks.
426
427 Some files are created in the tracing directory when this
428 is enabled:
429
430 hwlat_detector/width - time in usecs for how long to spin for
431 hwlat_detector/window - time in usecs between the start of each
432 iteration
433
434 A kernel thread is created that will spin with interrupts disabled
435 for "width" microseconds in every "window" cycle. It will not spin
436 for "window - width" microseconds, where the system can
437 continue to operate.
438
439 The output will appear in the trace and trace_pipe files.
440
441 When the tracer is not running, it has no affect on the system,
442 but when it is running, it can cause the system to be
443 periodically non responsive. Do not run this tracer on a
444 production system.
445
446 To enable this tracer, echo in "hwlat" into the current_tracer
447 file. Every time a latency is greater than tracing_thresh, it will
448 be recorded into the ring buffer.
449
450config OSNOISE_TRACER
451 bool "OS Noise tracer"
452 select GENERIC_TRACER
453 select TRACER_MAX_TRACE
454 help
455 In the context of high-performance computing (HPC), the Operating
456 System Noise (osnoise) refers to the interference experienced by an
457 application due to activities inside the operating system. In the
458 context of Linux, NMIs, IRQs, SoftIRQs, and any other system thread
459 can cause noise to the system. Moreover, hardware-related jobs can
460 also cause noise, for example, via SMIs.
461
462 The osnoise tracer leverages the hwlat_detector by running a similar
463 loop with preemption, SoftIRQs and IRQs enabled, thus allowing all
464 the sources of osnoise during its execution. The osnoise tracer takes
465 note of the entry and exit point of any source of interferences,
466 increasing a per-cpu interference counter. It saves an interference
467 counter for each source of interference. The interference counter for
468 NMI, IRQs, SoftIRQs, and threads is increased anytime the tool
469 observes these interferences' entry events. When a noise happens
470 without any interference from the operating system level, the
471 hardware noise counter increases, pointing to a hardware-related
472 noise. In this way, osnoise can account for any source of
473 interference. At the end of the period, the osnoise tracer prints
474 the sum of all noise, the max single noise, the percentage of CPU
475 available for the thread, and the counters for the noise sources.
476
477 In addition to the tracer, a set of tracepoints were added to
478 facilitate the identification of the osnoise source.
479
480 The output will appear in the trace and trace_pipe files.
481
482 To enable this tracer, echo in "osnoise" into the current_tracer
483 file.
484
485config TIMERLAT_TRACER
486 bool "Timerlat tracer"
487 select OSNOISE_TRACER
488 select GENERIC_TRACER
489 help
490 The timerlat tracer aims to help the preemptive kernel developers
491 to find sources of wakeup latencies of real-time threads.
492
493 The tracer creates a per-cpu kernel thread with real-time priority.
494 The tracer thread sets a periodic timer to wakeup itself, and goes
495 to sleep waiting for the timer to fire. At the wakeup, the thread
496 then computes a wakeup latency value as the difference between
497 the current time and the absolute time that the timer was set
498 to expire.
499
500 The tracer prints two lines at every activation. The first is the
501 timer latency observed at the hardirq context before the
502 activation of the thread. The second is the timer latency observed
503 by the thread, which is the same level that cyclictest reports. The
504 ACTIVATION ID field serves to relate the irq execution to its
505 respective thread execution.
506
507 The tracer is build on top of osnoise tracer, and the osnoise:
508 events can be used to trace the source of interference from NMI,
509 IRQs and other threads. It also enables the capture of the
510 stacktrace at the IRQ context, which helps to identify the code
511 path that can cause thread delay.
512
513config MMIOTRACE
514 bool "Memory mapped IO tracing"
515 depends on HAVE_MMIOTRACE_SUPPORT && PCI
516 select GENERIC_TRACER
517 help
518 Mmiotrace traces Memory Mapped I/O access and is meant for
519 debugging and reverse engineering. It is called from the ioremap
520 implementation and works via page faults. Tracing is disabled by
521 default and can be enabled at run-time.
522
523 See Documentation/trace/mmiotrace.rst.
524 If you are not helping to develop drivers, say N.
525
526config ENABLE_DEFAULT_TRACERS
527 bool "Trace process context switches and events"
528 depends on !GENERIC_TRACER
529 select TRACING
530 help
531 This tracer hooks to various trace points in the kernel,
532 allowing the user to pick and choose which trace point they
533 want to trace. It also includes the sched_switch tracer plugin.
534
535config FTRACE_SYSCALLS
536 bool "Trace syscalls"
537 depends on HAVE_SYSCALL_TRACEPOINTS
538 select GENERIC_TRACER
539 select KALLSYMS
540 help
541 Basic tracer to catch the syscall entry and exit events.
542
543config TRACER_SNAPSHOT
544 bool "Create a snapshot trace buffer"
545 select TRACER_MAX_TRACE
546 help
547 Allow tracing users to take snapshot of the current buffer using the
548 ftrace interface, e.g.:
549
550 echo 1 > /sys/kernel/tracing/snapshot
551 cat snapshot
552
553config TRACER_SNAPSHOT_PER_CPU_SWAP
554 bool "Allow snapshot to swap per CPU"
555 depends on TRACER_SNAPSHOT
556 select RING_BUFFER_ALLOW_SWAP
557 help
558 Allow doing a snapshot of a single CPU buffer instead of a
559 full swap (all buffers). If this is set, then the following is
560 allowed:
561
562 echo 1 > /sys/kernel/tracing/per_cpu/cpu2/snapshot
563
564 After which, only the tracing buffer for CPU 2 was swapped with
565 the main tracing buffer, and the other CPU buffers remain the same.
566
567 When this is enabled, this adds a little more overhead to the
568 trace recording, as it needs to add some checks to synchronize
569 recording with swaps. But this does not affect the performance
570 of the overall system. This is enabled by default when the preempt
571 or irq latency tracers are enabled, as those need to swap as well
572 and already adds the overhead (plus a lot more).
573
574config TRACE_BRANCH_PROFILING
575 bool
576 select GENERIC_TRACER
577
578choice
579 prompt "Branch Profiling"
580 default BRANCH_PROFILE_NONE
581 help
582 The branch profiling is a software profiler. It will add hooks
583 into the C conditionals to test which path a branch takes.
584
585 The likely/unlikely profiler only looks at the conditions that
586 are annotated with a likely or unlikely macro.
587
588 The "all branch" profiler will profile every if-statement in the
589 kernel. This profiler will also enable the likely/unlikely
590 profiler.
591
592 Either of the above profilers adds a bit of overhead to the system.
593 If unsure, choose "No branch profiling".
594
595config BRANCH_PROFILE_NONE
596 bool "No branch profiling"
597 help
598 No branch profiling. Branch profiling adds a bit of overhead.
599 Only enable it if you want to analyse the branching behavior.
600 Otherwise keep it disabled.
601
602config PROFILE_ANNOTATED_BRANCHES
603 bool "Trace likely/unlikely profiler"
604 select TRACE_BRANCH_PROFILING
605 help
606 This tracer profiles all likely and unlikely macros
607 in the kernel. It will display the results in:
608
609 /sys/kernel/tracing/trace_stat/branch_annotated
610
611 Note: this will add a significant overhead; only turn this
612 on if you need to profile the system's use of these macros.
613
614config PROFILE_ALL_BRANCHES
615 bool "Profile all if conditionals" if !FORTIFY_SOURCE
616 select TRACE_BRANCH_PROFILING
617 help
618 This tracer profiles all branch conditions. Every if ()
619 taken in the kernel is recorded whether it hit or miss.
620 The results will be displayed in:
621
622 /sys/kernel/tracing/trace_stat/branch_all
623
624 This option also enables the likely/unlikely profiler.
625
626 This configuration, when enabled, will impose a great overhead
627 on the system. This should only be enabled when the system
628 is to be analyzed in much detail.
629endchoice
630
631config TRACING_BRANCHES
632 bool
633 help
634 Selected by tracers that will trace the likely and unlikely
635 conditions. This prevents the tracers themselves from being
636 profiled. Profiling the tracing infrastructure can only happen
637 when the likelys and unlikelys are not being traced.
638
639config BRANCH_TRACER
640 bool "Trace likely/unlikely instances"
641 depends on TRACE_BRANCH_PROFILING
642 select TRACING_BRANCHES
643 help
644 This traces the events of likely and unlikely condition
645 calls in the kernel. The difference between this and the
646 "Trace likely/unlikely profiler" is that this is not a
647 histogram of the callers, but actually places the calling
648 events into a running trace buffer to see when and where the
649 events happened, as well as their results.
650
651 Say N if unsure.
652
653config BLK_DEV_IO_TRACE
654 bool "Support for tracing block IO actions"
655 depends on SYSFS
656 depends on BLOCK
657 select RELAY
658 select DEBUG_FS
659 select TRACEPOINTS
660 select GENERIC_TRACER
661 select STACKTRACE
662 help
663 Say Y here if you want to be able to trace the block layer actions
664 on a given queue. Tracing allows you to see any traffic happening
665 on a block device queue. For more information (and the userspace
666 support tools needed), fetch the blktrace tools from:
667
668 git://git.kernel.dk/blktrace.git
669
670 Tracing also is possible using the ftrace interface, e.g.:
671
672 echo 1 > /sys/block/sda/sda1/trace/enable
673 echo blk > /sys/kernel/tracing/current_tracer
674 cat /sys/kernel/tracing/trace_pipe
675
676 If unsure, say N.
677
678config FPROBE_EVENTS
679 depends on FPROBE
680 depends on HAVE_REGS_AND_STACK_ACCESS_API
681 bool "Enable fprobe-based dynamic events"
682 select TRACING
683 select PROBE_EVENTS
684 select DYNAMIC_EVENTS
685 default y
686 help
687 This allows user to add tracing events on the function entry and
688 exit via ftrace interface. The syntax is same as the kprobe events
689 and the kprobe events on function entry and exit will be
690 transparently converted to this fprobe events.
691
692config PROBE_EVENTS_BTF_ARGS
693 depends on HAVE_FUNCTION_ARG_ACCESS_API
694 depends on FPROBE_EVENTS || KPROBE_EVENTS
695 depends on DEBUG_INFO_BTF && BPF_SYSCALL
696 bool "Support BTF function arguments for probe events"
697 default y
698 help
699 The user can specify the arguments of the probe event using the names
700 of the arguments of the probed function, when the probe location is a
701 kernel function entry or a tracepoint.
702 This is available only if BTF (BPF Type Format) support is enabled.
703
704config KPROBE_EVENTS
705 depends on KPROBES
706 depends on HAVE_REGS_AND_STACK_ACCESS_API
707 bool "Enable kprobes-based dynamic events"
708 select TRACING
709 select PROBE_EVENTS
710 select DYNAMIC_EVENTS
711 default y
712 help
713 This allows the user to add tracing events (similar to tracepoints)
714 on the fly via the ftrace interface. See
715 Documentation/trace/kprobetrace.rst for more details.
716
717 Those events can be inserted wherever kprobes can probe, and record
718 various register and memory values.
719
720 This option is also required by perf-probe subcommand of perf tools.
721 If you want to use perf tools, this option is strongly recommended.
722
723config KPROBE_EVENTS_ON_NOTRACE
724 bool "Do NOT protect notrace function from kprobe events"
725 depends on KPROBE_EVENTS
726 depends on DYNAMIC_FTRACE
727 default n
728 help
729 This is only for the developers who want to debug ftrace itself
730 using kprobe events.
731
732 If kprobes can use ftrace instead of breakpoint, ftrace related
733 functions are protected from kprobe-events to prevent an infinite
734 recursion or any unexpected execution path which leads to a kernel
735 crash.
736
737 This option disables such protection and allows you to put kprobe
738 events on ftrace functions for debugging ftrace by itself.
739 Note that this might let you shoot yourself in the foot.
740
741 If unsure, say N.
742
743config UPROBE_EVENTS
744 bool "Enable uprobes-based dynamic events"
745 depends on ARCH_SUPPORTS_UPROBES
746 depends on MMU
747 depends on PERF_EVENTS
748 select UPROBES
749 select PROBE_EVENTS
750 select DYNAMIC_EVENTS
751 select TRACING
752 default y
753 help
754 This allows the user to add tracing events on top of userspace
755 dynamic events (similar to tracepoints) on the fly via the trace
756 events interface. Those events can be inserted wherever uprobes
757 can probe, and record various registers.
758 This option is required if you plan to use perf-probe subcommand
759 of perf tools on user space applications.
760
761config BPF_EVENTS
762 depends on BPF_SYSCALL
763 depends on (KPROBE_EVENTS || UPROBE_EVENTS) && PERF_EVENTS
764 bool
765 default y
766 help
767 This allows the user to attach BPF programs to kprobe, uprobe, and
768 tracepoint events.
769
770config DYNAMIC_EVENTS
771 def_bool n
772
773config PROBE_EVENTS
774 def_bool n
775
776config BPF_KPROBE_OVERRIDE
777 bool "Enable BPF programs to override a kprobed function"
778 depends on BPF_EVENTS
779 depends on FUNCTION_ERROR_INJECTION
780 default n
781 help
782 Allows BPF to override the execution of a probed function and
783 set a different return value. This is used for error injection.
784
785config FTRACE_MCOUNT_RECORD
786 def_bool y
787 depends on DYNAMIC_FTRACE
788 depends on HAVE_FTRACE_MCOUNT_RECORD
789
790config FTRACE_MCOUNT_USE_PATCHABLE_FUNCTION_ENTRY
791 bool
792 depends on FTRACE_MCOUNT_RECORD
793
794config FTRACE_MCOUNT_USE_CC
795 def_bool y
796 depends on $(cc-option,-mrecord-mcount)
797 depends on !FTRACE_MCOUNT_USE_PATCHABLE_FUNCTION_ENTRY
798 depends on FTRACE_MCOUNT_RECORD
799
800config FTRACE_MCOUNT_USE_OBJTOOL
801 def_bool y
802 depends on HAVE_OBJTOOL_MCOUNT
803 depends on !FTRACE_MCOUNT_USE_PATCHABLE_FUNCTION_ENTRY
804 depends on !FTRACE_MCOUNT_USE_CC
805 depends on FTRACE_MCOUNT_RECORD
806 select OBJTOOL
807
808config FTRACE_MCOUNT_USE_RECORDMCOUNT
809 def_bool y
810 depends on !FTRACE_MCOUNT_USE_PATCHABLE_FUNCTION_ENTRY
811 depends on !FTRACE_MCOUNT_USE_CC
812 depends on !FTRACE_MCOUNT_USE_OBJTOOL
813 depends on FTRACE_MCOUNT_RECORD
814
815config TRACING_MAP
816 bool
817 depends on ARCH_HAVE_NMI_SAFE_CMPXCHG
818 help
819 tracing_map is a special-purpose lock-free map for tracing,
820 separated out as a stand-alone facility in order to allow it
821 to be shared between multiple tracers. It isn't meant to be
822 generally used outside of that context, and is normally
823 selected by tracers that use it.
824
825config SYNTH_EVENTS
826 bool "Synthetic trace events"
827 select TRACING
828 select DYNAMIC_EVENTS
829 default n
830 help
831 Synthetic events are user-defined trace events that can be
832 used to combine data from other trace events or in fact any
833 data source. Synthetic events can be generated indirectly
834 via the trace() action of histogram triggers or directly
835 by way of an in-kernel API.
836
837 See Documentation/trace/events.rst or
838 Documentation/trace/histogram.rst for details and examples.
839
840 If in doubt, say N.
841
842config USER_EVENTS
843 bool "User trace events"
844 select TRACING
845 select DYNAMIC_EVENTS
846 help
847 User trace events are user-defined trace events that
848 can be used like an existing kernel trace event. User trace
849 events are generated by writing to a tracefs file. User
850 processes can determine if their tracing events should be
851 generated by registering a value and bit with the kernel
852 that reflects when it is enabled or not.
853
854 See Documentation/trace/user_events.rst.
855 If in doubt, say N.
856
857config HIST_TRIGGERS
858 bool "Histogram triggers"
859 depends on ARCH_HAVE_NMI_SAFE_CMPXCHG
860 select TRACING_MAP
861 select TRACING
862 select DYNAMIC_EVENTS
863 select SYNTH_EVENTS
864 default n
865 help
866 Hist triggers allow one or more arbitrary trace event fields
867 to be aggregated into hash tables and dumped to stdout by
868 reading a debugfs/tracefs file. They're useful for
869 gathering quick and dirty (though precise) summaries of
870 event activity as an initial guide for further investigation
871 using more advanced tools.
872
873 Inter-event tracing of quantities such as latencies is also
874 supported using hist triggers under this option.
875
876 See Documentation/trace/histogram.rst.
877 If in doubt, say N.
878
879config TRACE_EVENT_INJECT
880 bool "Trace event injection"
881 depends on TRACING
882 help
883 Allow user-space to inject a specific trace event into the ring
884 buffer. This is mainly used for testing purpose.
885
886 If unsure, say N.
887
888config TRACEPOINT_BENCHMARK
889 bool "Add tracepoint that benchmarks tracepoints"
890 help
891 This option creates the tracepoint "benchmark:benchmark_event".
892 When the tracepoint is enabled, it kicks off a kernel thread that
893 goes into an infinite loop (calling cond_resched() to let other tasks
894 run), and calls the tracepoint. Each iteration will record the time
895 it took to write to the tracepoint and the next iteration that
896 data will be passed to the tracepoint itself. That is, the tracepoint
897 will report the time it took to do the previous tracepoint.
898 The string written to the tracepoint is a static string of 128 bytes
899 to keep the time the same. The initial string is simply a write of
900 "START". The second string records the cold cache time of the first
901 write which is not added to the rest of the calculations.
902
903 As it is a tight loop, it benchmarks as hot cache. That's fine because
904 we care most about hot paths that are probably in cache already.
905
906 An example of the output:
907
908 START
909 first=3672 [COLD CACHED]
910 last=632 first=3672 max=632 min=632 avg=316 std=446 std^2=199712
911 last=278 first=3672 max=632 min=278 avg=303 std=316 std^2=100337
912 last=277 first=3672 max=632 min=277 avg=296 std=258 std^2=67064
913 last=273 first=3672 max=632 min=273 avg=292 std=224 std^2=50411
914 last=273 first=3672 max=632 min=273 avg=288 std=200 std^2=40389
915 last=281 first=3672 max=632 min=273 avg=287 std=183 std^2=33666
916
917
918config RING_BUFFER_BENCHMARK
919 tristate "Ring buffer benchmark stress tester"
920 depends on RING_BUFFER
921 help
922 This option creates a test to stress the ring buffer and benchmark it.
923 It creates its own ring buffer such that it will not interfere with
924 any other users of the ring buffer (such as ftrace). It then creates
925 a producer and consumer that will run for 10 seconds and sleep for
926 10 seconds. Each interval it will print out the number of events
927 it recorded and give a rough estimate of how long each iteration took.
928
929 It does not disable interrupts or raise its priority, so it may be
930 affected by processes that are running.
931
932 If unsure, say N.
933
934config TRACE_EVAL_MAP_FILE
935 bool "Show eval mappings for trace events"
936 depends on TRACING
937 help
938 The "print fmt" of the trace events will show the enum/sizeof names
939 instead of their values. This can cause problems for user space tools
940 that use this string to parse the raw data as user space does not know
941 how to convert the string to its value.
942
943 To fix this, there's a special macro in the kernel that can be used
944 to convert an enum/sizeof into its value. If this macro is used, then
945 the print fmt strings will be converted to their values.
946
947 If something does not get converted properly, this option can be
948 used to show what enums/sizeof the kernel tried to convert.
949
950 This option is for debugging the conversions. A file is created
951 in the tracing directory called "eval_map" that will show the
952 names matched with their values and what trace event system they
953 belong too.
954
955 Normally, the mapping of the strings to values will be freed after
956 boot up or module load. With this option, they will not be freed, as
957 they are needed for the "eval_map" file. Enabling this option will
958 increase the memory footprint of the running kernel.
959
960 If unsure, say N.
961
962config FTRACE_RECORD_RECURSION
963 bool "Record functions that recurse in function tracing"
964 depends on FUNCTION_TRACER
965 help
966 All callbacks that attach to the function tracing have some sort
967 of protection against recursion. Even though the protection exists,
968 it adds overhead. This option will create a file in the tracefs
969 file system called "recursed_functions" that will list the functions
970 that triggered a recursion.
971
972 This will add more overhead to cases that have recursion.
973
974 If unsure, say N
975
976config FTRACE_RECORD_RECURSION_SIZE
977 int "Max number of recursed functions to record"
978 default 128
979 depends on FTRACE_RECORD_RECURSION
980 help
981 This defines the limit of number of functions that can be
982 listed in the "recursed_functions" file, that lists all
983 the functions that caused a recursion to happen.
984 This file can be reset, but the limit can not change in
985 size at runtime.
986
987config FTRACE_VALIDATE_RCU_IS_WATCHING
988 bool "Validate RCU is on during ftrace execution"
989 depends on FUNCTION_TRACER
990 depends on ARCH_WANTS_NO_INSTR
991 help
992 All callbacks that attach to the function tracing have some sort of
993 protection against recursion. This option is only to verify that
994 ftrace (and other users of ftrace_test_recursion_trylock()) are not
995 called outside of RCU, as if they are, it can cause a race. But it
996 also has a noticeable overhead when enabled.
997
998 If unsure, say N
999
1000config RING_BUFFER_RECORD_RECURSION
1001 bool "Record functions that recurse in the ring buffer"
1002 depends on FTRACE_RECORD_RECURSION
1003 # default y, because it is coupled with FTRACE_RECORD_RECURSION
1004 default y
1005 help
1006 The ring buffer has its own internal recursion. Although when
1007 recursion happens it won't cause harm because of the protection,
1008 but it does cause unwanted overhead. Enabling this option will
1009 place where recursion was detected into the ftrace "recursed_functions"
1010 file.
1011
1012 This will add more overhead to cases that have recursion.
1013
1014config GCOV_PROFILE_FTRACE
1015 bool "Enable GCOV profiling on ftrace subsystem"
1016 depends on GCOV_KERNEL
1017 help
1018 Enable GCOV profiling on ftrace subsystem for checking
1019 which functions/lines are tested.
1020
1021 If unsure, say N.
1022
1023 Note that on a kernel compiled with this config, ftrace will
1024 run significantly slower.
1025
1026config FTRACE_SELFTEST
1027 bool
1028
1029config FTRACE_STARTUP_TEST
1030 bool "Perform a startup test on ftrace"
1031 depends on GENERIC_TRACER
1032 select FTRACE_SELFTEST
1033 help
1034 This option performs a series of startup tests on ftrace. On bootup
1035 a series of tests are made to verify that the tracer is
1036 functioning properly. It will do tests on all the configured
1037 tracers of ftrace.
1038
1039config EVENT_TRACE_STARTUP_TEST
1040 bool "Run selftest on trace events"
1041 depends on FTRACE_STARTUP_TEST
1042 default y
1043 help
1044 This option performs a test on all trace events in the system.
1045 It basically just enables each event and runs some code that
1046 will trigger events (not necessarily the event it enables)
1047 This may take some time run as there are a lot of events.
1048
1049config EVENT_TRACE_TEST_SYSCALLS
1050 bool "Run selftest on syscall events"
1051 depends on EVENT_TRACE_STARTUP_TEST
1052 help
1053 This option will also enable testing every syscall event.
1054 It only enables the event and disables it and runs various loads
1055 with the event enabled. This adds a bit more time for kernel boot
1056 up since it runs this on every system call defined.
1057
1058 TBD - enable a way to actually call the syscalls as we test their
1059 events
1060
1061config FTRACE_SORT_STARTUP_TEST
1062 bool "Verify compile time sorting of ftrace functions"
1063 depends on DYNAMIC_FTRACE
1064 depends on BUILDTIME_MCOUNT_SORT
1065 help
1066 Sorting of the mcount_loc sections that is used to find the
1067 where the ftrace knows where to patch functions for tracing
1068 and other callbacks is done at compile time. But if the sort
1069 is not done correctly, it will cause non-deterministic failures.
1070 When this is set, the sorted sections will be verified that they
1071 are in deed sorted and will warn if they are not.
1072
1073 If unsure, say N
1074
1075config RING_BUFFER_STARTUP_TEST
1076 bool "Ring buffer startup self test"
1077 depends on RING_BUFFER
1078 help
1079 Run a simple self test on the ring buffer on boot up. Late in the
1080 kernel boot sequence, the test will start that kicks off
1081 a thread per cpu. Each thread will write various size events
1082 into the ring buffer. Another thread is created to send IPIs
1083 to each of the threads, where the IPI handler will also write
1084 to the ring buffer, to test/stress the nesting ability.
1085 If any anomalies are discovered, a warning will be displayed
1086 and all ring buffers will be disabled.
1087
1088 The test runs for 10 seconds. This will slow your boot time
1089 by at least 10 more seconds.
1090
1091 At the end of the test, statistics and more checks are done.
1092 It will output the stats of each per cpu buffer: What
1093 was written, the sizes, what was read, what was lost, and
1094 other similar details.
1095
1096 If unsure, say N
1097
1098config RING_BUFFER_VALIDATE_TIME_DELTAS
1099 bool "Verify ring buffer time stamp deltas"
1100 depends on RING_BUFFER
1101 help
1102 This will audit the time stamps on the ring buffer sub
1103 buffer to make sure that all the time deltas for the
1104 events on a sub buffer matches the current time stamp.
1105 This audit is performed for every event that is not
1106 interrupted, or interrupting another event. A check
1107 is also made when traversing sub buffers to make sure
1108 that all the deltas on the previous sub buffer do not
1109 add up to be greater than the current time stamp.
1110
1111 NOTE: This adds significant overhead to recording of events,
1112 and should only be used to test the logic of the ring buffer.
1113 Do not use it on production systems.
1114
1115 Only say Y if you understand what this does, and you
1116 still want it enabled. Otherwise say N
1117
1118config MMIOTRACE_TEST
1119 tristate "Test module for mmiotrace"
1120 depends on MMIOTRACE && m
1121 help
1122 This is a dumb module for testing mmiotrace. It is very dangerous
1123 as it will write garbage to IO memory starting at a given address.
1124 However, it should be safe to use on e.g. unused portion of VRAM.
1125
1126 Say N, unless you absolutely know what you are doing.
1127
1128config PREEMPTIRQ_DELAY_TEST
1129 tristate "Test module to create a preempt / IRQ disable delay thread to test latency tracers"
1130 depends on m
1131 help
1132 Select this option to build a test module that can help test latency
1133 tracers by executing a preempt or irq disable section with a user
1134 configurable delay. The module busy waits for the duration of the
1135 critical section.
1136
1137 For example, the following invocation generates a burst of three
1138 irq-disabled critical sections for 500us:
1139 modprobe preemptirq_delay_test test_mode=irq delay=500 burst_size=3
1140
1141 What's more, if you want to attach the test on the cpu which the latency
1142 tracer is running on, specify cpu_affinity=cpu_num at the end of the
1143 command.
1144
1145 If unsure, say N
1146
1147config SYNTH_EVENT_GEN_TEST
1148 tristate "Test module for in-kernel synthetic event generation"
1149 depends on SYNTH_EVENTS && m
1150 help
1151 This option creates a test module to check the base
1152 functionality of in-kernel synthetic event definition and
1153 generation.
1154
1155 To test, insert the module, and then check the trace buffer
1156 for the generated sample events.
1157
1158 If unsure, say N.
1159
1160config KPROBE_EVENT_GEN_TEST
1161 tristate "Test module for in-kernel kprobe event generation"
1162 depends on KPROBE_EVENTS && m
1163 help
1164 This option creates a test module to check the base
1165 functionality of in-kernel kprobe event definition.
1166
1167 To test, insert the module, and then check the trace buffer
1168 for the generated kprobe events.
1169
1170 If unsure, say N.
1171
1172config HIST_TRIGGERS_DEBUG
1173 bool "Hist trigger debug support"
1174 depends on HIST_TRIGGERS
1175 help
1176 Add "hist_debug" file for each event, which when read will
1177 dump out a bunch of internal details about the hist triggers
1178 defined on that event.
1179
1180 The hist_debug file serves a couple of purposes:
1181
1182 - Helps developers verify that nothing is broken.
1183
1184 - Provides educational information to support the details
1185 of the hist trigger internals as described by
1186 Documentation/trace/histogram-design.rst.
1187
1188 The hist_debug output only covers the data structures
1189 related to the histogram definitions themselves and doesn't
1190 display the internals of map buckets or variable values of
1191 running histograms.
1192
1193 If unsure, say N.
1194
1195source "kernel/trace/rv/Kconfig"
1196
1197endif # FTRACE
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_FTRACE_NMI_ENTER
14 bool
15 help
16 See Documentation/trace/ftrace-design.rst
17
18config HAVE_FUNCTION_TRACER
19 bool
20 help
21 See Documentation/trace/ftrace-design.rst
22
23config HAVE_FUNCTION_GRAPH_TRACER
24 bool
25 help
26 See Documentation/trace/ftrace-design.rst
27
28config HAVE_DYNAMIC_FTRACE
29 bool
30 help
31 See Documentation/trace/ftrace-design.rst
32
33config HAVE_DYNAMIC_FTRACE_WITH_REGS
34 bool
35
36config HAVE_FTRACE_MCOUNT_RECORD
37 bool
38 help
39 See Documentation/trace/ftrace-design.rst
40
41config HAVE_SYSCALL_TRACEPOINTS
42 bool
43 help
44 See Documentation/trace/ftrace-design.rst
45
46config HAVE_FENTRY
47 bool
48 help
49 Arch supports the gcc options -pg with -mfentry
50
51config HAVE_NOP_MCOUNT
52 bool
53 help
54 Arch supports the gcc options -pg with -mrecord-mcount and -nop-mcount
55
56config HAVE_C_RECORDMCOUNT
57 bool
58 help
59 C version of recordmcount available?
60
61config TRACER_MAX_TRACE
62 bool
63
64config TRACE_CLOCK
65 bool
66
67config RING_BUFFER
68 bool
69 select TRACE_CLOCK
70 select IRQ_WORK
71
72config FTRACE_NMI_ENTER
73 bool
74 depends on HAVE_FTRACE_NMI_ENTER
75 default y
76
77config EVENT_TRACING
78 select CONTEXT_SWITCH_TRACER
79 select GLOB
80 bool
81
82config CONTEXT_SWITCH_TRACER
83 bool
84
85config RING_BUFFER_ALLOW_SWAP
86 bool
87 help
88 Allow the use of ring_buffer_swap_cpu.
89 Adds a very slight overhead to tracing when enabled.
90
91config PREEMPTIRQ_TRACEPOINTS
92 bool
93 depends on TRACE_PREEMPT_TOGGLE || TRACE_IRQFLAGS
94 select TRACING
95 default y
96 help
97 Create preempt/irq toggle tracepoints if needed, so that other parts
98 of the kernel can use them to generate or add hooks to them.
99
100# All tracer options should select GENERIC_TRACER. For those options that are
101# enabled by all tracers (context switch and event tracer) they select TRACING.
102# This allows those options to appear when no other tracer is selected. But the
103# options do not appear when something else selects it. We need the two options
104# GENERIC_TRACER and TRACING to avoid circular dependencies to accomplish the
105# hiding of the automatic options.
106
107config TRACING
108 bool
109 select DEBUG_FS
110 select RING_BUFFER
111 select STACKTRACE if STACKTRACE_SUPPORT
112 select TRACEPOINTS
113 select NOP_TRACER
114 select BINARY_PRINTF
115 select EVENT_TRACING
116 select TRACE_CLOCK
117
118config GENERIC_TRACER
119 bool
120 select TRACING
121
122#
123# Minimum requirements an architecture has to meet for us to
124# be able to offer generic tracing facilities:
125#
126config TRACING_SUPPORT
127 bool
128 depends on TRACE_IRQFLAGS_SUPPORT
129 depends on STACKTRACE_SUPPORT
130 default y
131
132if TRACING_SUPPORT
133
134menuconfig FTRACE
135 bool "Tracers"
136 default y if DEBUG_KERNEL
137 help
138 Enable the kernel tracing infrastructure.
139
140if FTRACE
141
142config FUNCTION_TRACER
143 bool "Kernel Function Tracer"
144 depends on HAVE_FUNCTION_TRACER
145 select KALLSYMS
146 select GENERIC_TRACER
147 select CONTEXT_SWITCH_TRACER
148 select GLOB
149 select TASKS_RCU if PREEMPTION
150 help
151 Enable the kernel to trace every kernel function. This is done
152 by using a compiler feature to insert a small, 5-byte No-Operation
153 instruction at the beginning of every kernel function, which NOP
154 sequence is then dynamically patched into a tracer call when
155 tracing is enabled by the administrator. If it's runtime disabled
156 (the bootup default), then the overhead of the instructions is very
157 small and not measurable even in micro-benchmarks.
158
159config FUNCTION_GRAPH_TRACER
160 bool "Kernel Function Graph Tracer"
161 depends on HAVE_FUNCTION_GRAPH_TRACER
162 depends on FUNCTION_TRACER
163 depends on !X86_32 || !CC_OPTIMIZE_FOR_SIZE
164 default y
165 help
166 Enable the kernel to trace a function at both its return
167 and its entry.
168 Its first purpose is to trace the duration of functions and
169 draw a call graph for each thread with some information like
170 the return value. This is done by setting the current return
171 address on the current task structure into a stack of calls.
172
173config TRACE_PREEMPT_TOGGLE
174 bool
175 help
176 Enables hooks which will be called when preemption is first disabled,
177 and last enabled.
178
179config PREEMPTIRQ_EVENTS
180 bool "Enable trace events for preempt and irq disable/enable"
181 select TRACE_IRQFLAGS
182 select TRACE_PREEMPT_TOGGLE if PREEMPTION
183 select GENERIC_TRACER
184 default n
185 help
186 Enable tracing of disable and enable events for preemption and irqs.
187
188config IRQSOFF_TRACER
189 bool "Interrupts-off Latency Tracer"
190 default n
191 depends on TRACE_IRQFLAGS_SUPPORT
192 depends on !ARCH_USES_GETTIMEOFFSET
193 select TRACE_IRQFLAGS
194 select GENERIC_TRACER
195 select TRACER_MAX_TRACE
196 select RING_BUFFER_ALLOW_SWAP
197 select TRACER_SNAPSHOT
198 select TRACER_SNAPSHOT_PER_CPU_SWAP
199 help
200 This option measures the time spent in irqs-off critical
201 sections, with microsecond accuracy.
202
203 The default measurement method is a maximum search, which is
204 disabled by default and can be runtime (re-)started
205 via:
206
207 echo 0 > /sys/kernel/debug/tracing/tracing_max_latency
208
209 (Note that kernel size and overhead increase with this option
210 enabled. This option and the preempt-off timing option can be
211 used together or separately.)
212
213config PREEMPT_TRACER
214 bool "Preemption-off Latency Tracer"
215 default n
216 depends on !ARCH_USES_GETTIMEOFFSET
217 depends on PREEMPTION
218 select GENERIC_TRACER
219 select TRACER_MAX_TRACE
220 select RING_BUFFER_ALLOW_SWAP
221 select TRACER_SNAPSHOT
222 select TRACER_SNAPSHOT_PER_CPU_SWAP
223 select TRACE_PREEMPT_TOGGLE
224 help
225 This option measures the time spent in preemption-off critical
226 sections, with microsecond accuracy.
227
228 The default measurement method is a maximum search, which is
229 disabled by default and can be runtime (re-)started
230 via:
231
232 echo 0 > /sys/kernel/debug/tracing/tracing_max_latency
233
234 (Note that kernel size and overhead increase with this option
235 enabled. This option and the irqs-off timing option can be
236 used together or separately.)
237
238config SCHED_TRACER
239 bool "Scheduling Latency Tracer"
240 select GENERIC_TRACER
241 select CONTEXT_SWITCH_TRACER
242 select TRACER_MAX_TRACE
243 select TRACER_SNAPSHOT
244 help
245 This tracer tracks the latency of the highest priority task
246 to be scheduled in, starting from the point it has woken up.
247
248config HWLAT_TRACER
249 bool "Tracer to detect hardware latencies (like SMIs)"
250 select GENERIC_TRACER
251 help
252 This tracer, when enabled will create one or more kernel threads,
253 depending on what the cpumask file is set to, which each thread
254 spinning in a loop looking for interruptions caused by
255 something other than the kernel. For example, if a
256 System Management Interrupt (SMI) takes a noticeable amount of
257 time, this tracer will detect it. This is useful for testing
258 if a system is reliable for Real Time tasks.
259
260 Some files are created in the tracing directory when this
261 is enabled:
262
263 hwlat_detector/width - time in usecs for how long to spin for
264 hwlat_detector/window - time in usecs between the start of each
265 iteration
266
267 A kernel thread is created that will spin with interrupts disabled
268 for "width" microseconds in every "window" cycle. It will not spin
269 for "window - width" microseconds, where the system can
270 continue to operate.
271
272 The output will appear in the trace and trace_pipe files.
273
274 When the tracer is not running, it has no affect on the system,
275 but when it is running, it can cause the system to be
276 periodically non responsive. Do not run this tracer on a
277 production system.
278
279 To enable this tracer, echo in "hwlat" into the current_tracer
280 file. Every time a latency is greater than tracing_thresh, it will
281 be recorded into the ring buffer.
282
283config ENABLE_DEFAULT_TRACERS
284 bool "Trace process context switches and events"
285 depends on !GENERIC_TRACER
286 select TRACING
287 help
288 This tracer hooks to various trace points in the kernel,
289 allowing the user to pick and choose which trace point they
290 want to trace. It also includes the sched_switch tracer plugin.
291
292config FTRACE_SYSCALLS
293 bool "Trace syscalls"
294 depends on HAVE_SYSCALL_TRACEPOINTS
295 select GENERIC_TRACER
296 select KALLSYMS
297 help
298 Basic tracer to catch the syscall entry and exit events.
299
300config TRACER_SNAPSHOT
301 bool "Create a snapshot trace buffer"
302 select TRACER_MAX_TRACE
303 help
304 Allow tracing users to take snapshot of the current buffer using the
305 ftrace interface, e.g.:
306
307 echo 1 > /sys/kernel/debug/tracing/snapshot
308 cat snapshot
309
310config TRACER_SNAPSHOT_PER_CPU_SWAP
311 bool "Allow snapshot to swap per CPU"
312 depends on TRACER_SNAPSHOT
313 select RING_BUFFER_ALLOW_SWAP
314 help
315 Allow doing a snapshot of a single CPU buffer instead of a
316 full swap (all buffers). If this is set, then the following is
317 allowed:
318
319 echo 1 > /sys/kernel/debug/tracing/per_cpu/cpu2/snapshot
320
321 After which, only the tracing buffer for CPU 2 was swapped with
322 the main tracing buffer, and the other CPU buffers remain the same.
323
324 When this is enabled, this adds a little more overhead to the
325 trace recording, as it needs to add some checks to synchronize
326 recording with swaps. But this does not affect the performance
327 of the overall system. This is enabled by default when the preempt
328 or irq latency tracers are enabled, as those need to swap as well
329 and already adds the overhead (plus a lot more).
330
331config TRACE_BRANCH_PROFILING
332 bool
333 select GENERIC_TRACER
334
335choice
336 prompt "Branch Profiling"
337 default BRANCH_PROFILE_NONE
338 help
339 The branch profiling is a software profiler. It will add hooks
340 into the C conditionals to test which path a branch takes.
341
342 The likely/unlikely profiler only looks at the conditions that
343 are annotated with a likely or unlikely macro.
344
345 The "all branch" profiler will profile every if-statement in the
346 kernel. This profiler will also enable the likely/unlikely
347 profiler.
348
349 Either of the above profilers adds a bit of overhead to the system.
350 If unsure, choose "No branch profiling".
351
352config BRANCH_PROFILE_NONE
353 bool "No branch profiling"
354 help
355 No branch profiling. Branch profiling adds a bit of overhead.
356 Only enable it if you want to analyse the branching behavior.
357 Otherwise keep it disabled.
358
359config PROFILE_ANNOTATED_BRANCHES
360 bool "Trace likely/unlikely profiler"
361 select TRACE_BRANCH_PROFILING
362 help
363 This tracer profiles all likely and unlikely macros
364 in the kernel. It will display the results in:
365
366 /sys/kernel/debug/tracing/trace_stat/branch_annotated
367
368 Note: this will add a significant overhead; only turn this
369 on if you need to profile the system's use of these macros.
370
371config PROFILE_ALL_BRANCHES
372 bool "Profile all if conditionals" if !FORTIFY_SOURCE
373 select TRACE_BRANCH_PROFILING
374 imply CC_DISABLE_WARN_MAYBE_UNINITIALIZED # avoid false positives
375 help
376 This tracer profiles all branch conditions. Every if ()
377 taken in the kernel is recorded whether it hit or miss.
378 The results will be displayed in:
379
380 /sys/kernel/debug/tracing/trace_stat/branch_all
381
382 This option also enables the likely/unlikely profiler.
383
384 This configuration, when enabled, will impose a great overhead
385 on the system. This should only be enabled when the system
386 is to be analyzed in much detail.
387endchoice
388
389config TRACING_BRANCHES
390 bool
391 help
392 Selected by tracers that will trace the likely and unlikely
393 conditions. This prevents the tracers themselves from being
394 profiled. Profiling the tracing infrastructure can only happen
395 when the likelys and unlikelys are not being traced.
396
397config BRANCH_TRACER
398 bool "Trace likely/unlikely instances"
399 depends on TRACE_BRANCH_PROFILING
400 select TRACING_BRANCHES
401 help
402 This traces the events of likely and unlikely condition
403 calls in the kernel. The difference between this and the
404 "Trace likely/unlikely profiler" is that this is not a
405 histogram of the callers, but actually places the calling
406 events into a running trace buffer to see when and where the
407 events happened, as well as their results.
408
409 Say N if unsure.
410
411config STACK_TRACER
412 bool "Trace max stack"
413 depends on HAVE_FUNCTION_TRACER
414 select FUNCTION_TRACER
415 select STACKTRACE
416 select KALLSYMS
417 help
418 This special tracer records the maximum stack footprint of the
419 kernel and displays it in /sys/kernel/debug/tracing/stack_trace.
420
421 This tracer works by hooking into every function call that the
422 kernel executes, and keeping a maximum stack depth value and
423 stack-trace saved. If this is configured with DYNAMIC_FTRACE
424 then it will not have any overhead while the stack tracer
425 is disabled.
426
427 To enable the stack tracer on bootup, pass in 'stacktrace'
428 on the kernel command line.
429
430 The stack tracer can also be enabled or disabled via the
431 sysctl kernel.stack_tracer_enabled
432
433 Say N if unsure.
434
435config BLK_DEV_IO_TRACE
436 bool "Support for tracing block IO actions"
437 depends on SYSFS
438 depends on BLOCK
439 select RELAY
440 select DEBUG_FS
441 select TRACEPOINTS
442 select GENERIC_TRACER
443 select STACKTRACE
444 help
445 Say Y here if you want to be able to trace the block layer actions
446 on a given queue. Tracing allows you to see any traffic happening
447 on a block device queue. For more information (and the userspace
448 support tools needed), fetch the blktrace tools from:
449
450 git://git.kernel.dk/blktrace.git
451
452 Tracing also is possible using the ftrace interface, e.g.:
453
454 echo 1 > /sys/block/sda/sda1/trace/enable
455 echo blk > /sys/kernel/debug/tracing/current_tracer
456 cat /sys/kernel/debug/tracing/trace_pipe
457
458 If unsure, say N.
459
460config KPROBE_EVENTS
461 depends on KPROBES
462 depends on HAVE_REGS_AND_STACK_ACCESS_API
463 bool "Enable kprobes-based dynamic events"
464 select TRACING
465 select PROBE_EVENTS
466 select DYNAMIC_EVENTS
467 default y
468 help
469 This allows the user to add tracing events (similar to tracepoints)
470 on the fly via the ftrace interface. See
471 Documentation/trace/kprobetrace.rst for more details.
472
473 Those events can be inserted wherever kprobes can probe, and record
474 various register and memory values.
475
476 This option is also required by perf-probe subcommand of perf tools.
477 If you want to use perf tools, this option is strongly recommended.
478
479config KPROBE_EVENTS_ON_NOTRACE
480 bool "Do NOT protect notrace function from kprobe events"
481 depends on KPROBE_EVENTS
482 depends on KPROBES_ON_FTRACE
483 default n
484 help
485 This is only for the developers who want to debug ftrace itself
486 using kprobe events.
487
488 If kprobes can use ftrace instead of breakpoint, ftrace related
489 functions are protected from kprobe-events to prevent an infinit
490 recursion or any unexpected execution path which leads to a kernel
491 crash.
492
493 This option disables such protection and allows you to put kprobe
494 events on ftrace functions for debugging ftrace by itself.
495 Note that this might let you shoot yourself in the foot.
496
497 If unsure, say N.
498
499config UPROBE_EVENTS
500 bool "Enable uprobes-based dynamic events"
501 depends on ARCH_SUPPORTS_UPROBES
502 depends on MMU
503 depends on PERF_EVENTS
504 select UPROBES
505 select PROBE_EVENTS
506 select DYNAMIC_EVENTS
507 select TRACING
508 default y
509 help
510 This allows the user to add tracing events on top of userspace
511 dynamic events (similar to tracepoints) on the fly via the trace
512 events interface. Those events can be inserted wherever uprobes
513 can probe, and record various registers.
514 This option is required if you plan to use perf-probe subcommand
515 of perf tools on user space applications.
516
517config BPF_EVENTS
518 depends on BPF_SYSCALL
519 depends on (KPROBE_EVENTS || UPROBE_EVENTS) && PERF_EVENTS
520 bool
521 default y
522 help
523 This allows the user to attach BPF programs to kprobe, uprobe, and
524 tracepoint events.
525
526config DYNAMIC_EVENTS
527 def_bool n
528
529config PROBE_EVENTS
530 def_bool n
531
532config DYNAMIC_FTRACE
533 bool "enable/disable function tracing dynamically"
534 depends on FUNCTION_TRACER
535 depends on HAVE_DYNAMIC_FTRACE
536 default y
537 help
538 This option will modify all the calls to function tracing
539 dynamically (will patch them out of the binary image and
540 replace them with a No-Op instruction) on boot up. During
541 compile time, a table is made of all the locations that ftrace
542 can function trace, and this table is linked into the kernel
543 image. When this is enabled, functions can be individually
544 enabled, and the functions not enabled will not affect
545 performance of the system.
546
547 See the files in /sys/kernel/debug/tracing:
548 available_filter_functions
549 set_ftrace_filter
550 set_ftrace_notrace
551
552 This way a CONFIG_FUNCTION_TRACER kernel is slightly larger, but
553 otherwise has native performance as long as no tracing is active.
554
555config DYNAMIC_FTRACE_WITH_REGS
556 def_bool y
557 depends on DYNAMIC_FTRACE
558 depends on HAVE_DYNAMIC_FTRACE_WITH_REGS
559
560config FUNCTION_PROFILER
561 bool "Kernel function profiler"
562 depends on FUNCTION_TRACER
563 default n
564 help
565 This option enables the kernel function profiler. A file is created
566 in debugfs called function_profile_enabled which defaults to zero.
567 When a 1 is echoed into this file profiling begins, and when a
568 zero is entered, profiling stops. A "functions" file is created in
569 the trace_stat directory; this file shows the list of functions that
570 have been hit and their counters.
571
572 If in doubt, say N.
573
574config BPF_KPROBE_OVERRIDE
575 bool "Enable BPF programs to override a kprobed function"
576 depends on BPF_EVENTS
577 depends on FUNCTION_ERROR_INJECTION
578 default n
579 help
580 Allows BPF to override the execution of a probed function and
581 set a different return value. This is used for error injection.
582
583config FTRACE_MCOUNT_RECORD
584 def_bool y
585 depends on DYNAMIC_FTRACE
586 depends on HAVE_FTRACE_MCOUNT_RECORD
587
588config FTRACE_SELFTEST
589 bool
590
591config FTRACE_STARTUP_TEST
592 bool "Perform a startup test on ftrace"
593 depends on GENERIC_TRACER
594 select FTRACE_SELFTEST
595 help
596 This option performs a series of startup tests on ftrace. On bootup
597 a series of tests are made to verify that the tracer is
598 functioning properly. It will do tests on all the configured
599 tracers of ftrace.
600
601config EVENT_TRACE_STARTUP_TEST
602 bool "Run selftest on trace events"
603 depends on FTRACE_STARTUP_TEST
604 default y
605 help
606 This option performs a test on all trace events in the system.
607 It basically just enables each event and runs some code that
608 will trigger events (not necessarily the event it enables)
609 This may take some time run as there are a lot of events.
610
611config EVENT_TRACE_TEST_SYSCALLS
612 bool "Run selftest on syscall events"
613 depends on EVENT_TRACE_STARTUP_TEST
614 help
615 This option will also enable testing every syscall event.
616 It only enables the event and disables it and runs various loads
617 with the event enabled. This adds a bit more time for kernel boot
618 up since it runs this on every system call defined.
619
620 TBD - enable a way to actually call the syscalls as we test their
621 events
622
623config MMIOTRACE
624 bool "Memory mapped IO tracing"
625 depends on HAVE_MMIOTRACE_SUPPORT && PCI
626 select GENERIC_TRACER
627 help
628 Mmiotrace traces Memory Mapped I/O access and is meant for
629 debugging and reverse engineering. It is called from the ioremap
630 implementation and works via page faults. Tracing is disabled by
631 default and can be enabled at run-time.
632
633 See Documentation/trace/mmiotrace.rst.
634 If you are not helping to develop drivers, say N.
635
636config TRACING_MAP
637 bool
638 depends on ARCH_HAVE_NMI_SAFE_CMPXCHG
639 help
640 tracing_map is a special-purpose lock-free map for tracing,
641 separated out as a stand-alone facility in order to allow it
642 to be shared between multiple tracers. It isn't meant to be
643 generally used outside of that context, and is normally
644 selected by tracers that use it.
645
646config HIST_TRIGGERS
647 bool "Histogram triggers"
648 depends on ARCH_HAVE_NMI_SAFE_CMPXCHG
649 select TRACING_MAP
650 select TRACING
651 select DYNAMIC_EVENTS
652 default n
653 help
654 Hist triggers allow one or more arbitrary trace event fields
655 to be aggregated into hash tables and dumped to stdout by
656 reading a debugfs/tracefs file. They're useful for
657 gathering quick and dirty (though precise) summaries of
658 event activity as an initial guide for further investigation
659 using more advanced tools.
660
661 Inter-event tracing of quantities such as latencies is also
662 supported using hist triggers under this option.
663
664 See Documentation/trace/histogram.rst.
665 If in doubt, say N.
666
667config MMIOTRACE_TEST
668 tristate "Test module for mmiotrace"
669 depends on MMIOTRACE && m
670 help
671 This is a dumb module for testing mmiotrace. It is very dangerous
672 as it will write garbage to IO memory starting at a given address.
673 However, it should be safe to use on e.g. unused portion of VRAM.
674
675 Say N, unless you absolutely know what you are doing.
676
677config TRACEPOINT_BENCHMARK
678 bool "Add tracepoint that benchmarks tracepoints"
679 help
680 This option creates the tracepoint "benchmark:benchmark_event".
681 When the tracepoint is enabled, it kicks off a kernel thread that
682 goes into an infinite loop (calling cond_sched() to let other tasks
683 run), and calls the tracepoint. Each iteration will record the time
684 it took to write to the tracepoint and the next iteration that
685 data will be passed to the tracepoint itself. That is, the tracepoint
686 will report the time it took to do the previous tracepoint.
687 The string written to the tracepoint is a static string of 128 bytes
688 to keep the time the same. The initial string is simply a write of
689 "START". The second string records the cold cache time of the first
690 write which is not added to the rest of the calculations.
691
692 As it is a tight loop, it benchmarks as hot cache. That's fine because
693 we care most about hot paths that are probably in cache already.
694
695 An example of the output:
696
697 START
698 first=3672 [COLD CACHED]
699 last=632 first=3672 max=632 min=632 avg=316 std=446 std^2=199712
700 last=278 first=3672 max=632 min=278 avg=303 std=316 std^2=100337
701 last=277 first=3672 max=632 min=277 avg=296 std=258 std^2=67064
702 last=273 first=3672 max=632 min=273 avg=292 std=224 std^2=50411
703 last=273 first=3672 max=632 min=273 avg=288 std=200 std^2=40389
704 last=281 first=3672 max=632 min=273 avg=287 std=183 std^2=33666
705
706
707config RING_BUFFER_BENCHMARK
708 tristate "Ring buffer benchmark stress tester"
709 depends on RING_BUFFER
710 help
711 This option creates a test to stress the ring buffer and benchmark it.
712 It creates its own ring buffer such that it will not interfere with
713 any other users of the ring buffer (such as ftrace). It then creates
714 a producer and consumer that will run for 10 seconds and sleep for
715 10 seconds. Each interval it will print out the number of events
716 it recorded and give a rough estimate of how long each iteration took.
717
718 It does not disable interrupts or raise its priority, so it may be
719 affected by processes that are running.
720
721 If unsure, say N.
722
723config RING_BUFFER_STARTUP_TEST
724 bool "Ring buffer startup self test"
725 depends on RING_BUFFER
726 help
727 Run a simple self test on the ring buffer on boot up. Late in the
728 kernel boot sequence, the test will start that kicks off
729 a thread per cpu. Each thread will write various size events
730 into the ring buffer. Another thread is created to send IPIs
731 to each of the threads, where the IPI handler will also write
732 to the ring buffer, to test/stress the nesting ability.
733 If any anomalies are discovered, a warning will be displayed
734 and all ring buffers will be disabled.
735
736 The test runs for 10 seconds. This will slow your boot time
737 by at least 10 more seconds.
738
739 At the end of the test, statics and more checks are done.
740 It will output the stats of each per cpu buffer. What
741 was written, the sizes, what was read, what was lost, and
742 other similar details.
743
744 If unsure, say N
745
746config PREEMPTIRQ_DELAY_TEST
747 tristate "Preempt / IRQ disable delay thread to test latency tracers"
748 depends on m
749 help
750 Select this option to build a test module that can help test latency
751 tracers by executing a preempt or irq disable section with a user
752 configurable delay. The module busy waits for the duration of the
753 critical section.
754
755 For example, the following invocation forces a one-time irq-disabled
756 critical section for 500us:
757 modprobe preemptirq_delay_test test_mode=irq delay=500000
758
759 If unsure, say N
760
761config TRACE_EVAL_MAP_FILE
762 bool "Show eval mappings for trace events"
763 depends on TRACING
764 help
765 The "print fmt" of the trace events will show the enum/sizeof names
766 instead of their values. This can cause problems for user space tools
767 that use this string to parse the raw data as user space does not know
768 how to convert the string to its value.
769
770 To fix this, there's a special macro in the kernel that can be used
771 to convert an enum/sizeof into its value. If this macro is used, then
772 the print fmt strings will be converted to their values.
773
774 If something does not get converted properly, this option can be
775 used to show what enums/sizeof the kernel tried to convert.
776
777 This option is for debugging the conversions. A file is created
778 in the tracing directory called "eval_map" that will show the
779 names matched with their values and what trace event system they
780 belong too.
781
782 Normally, the mapping of the strings to values will be freed after
783 boot up or module load. With this option, they will not be freed, as
784 they are needed for the "eval_map" file. Enabling this option will
785 increase the memory footprint of the running kernel.
786
787 If unsure, say N
788
789config GCOV_PROFILE_FTRACE
790 bool "Enable GCOV profiling on ftrace subsystem"
791 depends on GCOV_KERNEL
792 help
793 Enable GCOV profiling on ftrace subsystem for checking
794 which functions/lines are tested.
795
796 If unsure, say N.
797
798 Note that on a kernel compiled with this config, ftrace will
799 run significantly slower.
800
801endif # FTRACE
802
803endif # TRACING_SUPPORT
804