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