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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_FREGS
35 bool
36
37config HAVE_FTRACE_GRAPH_FUNC
38 bool
39 help
40 True if ftrace_graph_func() is defined.
41
42config HAVE_DYNAMIC_FTRACE
43 bool
44 help
45 See Documentation/trace/ftrace-design.rst
46
47config HAVE_DYNAMIC_FTRACE_WITH_REGS
48 bool
49
50config HAVE_DYNAMIC_FTRACE_WITH_DIRECT_CALLS
51 bool
52
53config HAVE_SINGLE_FTRACE_DIRECT_OPS
54 bool
55
56config HAVE_DYNAMIC_FTRACE_WITH_CALL_OPS
57 bool
58
59config HAVE_EXTRA_IPI_TRACEPOINTS
60 bool
61 help
62 For architectures that use ipi_raise, ipi_entry and ipi_exit
63 tracepoints.
64
65config HAVE_DYNAMIC_FTRACE_WITH_ARGS
66 bool
67 help
68 If this is set, then arguments and stack can be found from
69 the ftrace_regs passed into the function callback regs parameter
70 by default, even without setting the REGS flag in the ftrace_ops.
71 This allows for use of ftrace_regs_get_argument() and
72 ftrace_regs_get_stack_pointer().
73
74config HAVE_FTRACE_REGS_HAVING_PT_REGS
75 bool
76 help
77 If this is set, ftrace_regs has pt_regs, thus it can convert to
78 pt_regs without allocating memory.
79
80config HAVE_DYNAMIC_FTRACE_NO_PATCHABLE
81 bool
82 help
83 If the architecture generates __patchable_function_entries sections
84 but does not want them included in the ftrace locations.
85
86config HAVE_DYNAMIC_FTRACE_WITH_JMP
87 bool
88 help
89 If the architecture supports to replace the __fentry__ with a
90 "jmp" instruction.
91
92config HAVE_SYSCALL_TRACEPOINTS
93 bool
94 help
95 See Documentation/trace/ftrace-design.rst
96
97config HAVE_FENTRY
98 bool
99 help
100 Arch supports the gcc options -pg with -mfentry
101
102config HAVE_NOP_MCOUNT
103 bool
104 help
105 Arch supports the gcc options -pg with -mrecord-mcount and -nop-mcount
106
107config HAVE_OBJTOOL_MCOUNT
108 bool
109 help
110 Arch supports objtool --mcount
111
112config HAVE_OBJTOOL_NOP_MCOUNT
113 bool
114 help
115 Arch supports the objtool options --mcount with --mnop.
116 An architecture can select this if it wants to enable nop'ing
117 of ftrace locations.
118
119config HAVE_C_RECORDMCOUNT
120 bool
121 help
122 C version of recordmcount available?
123
124config HAVE_BUILDTIME_MCOUNT_SORT
125 bool
126 help
127 An architecture selects this if it sorts the mcount_loc section
128 at build time.
129
130config BUILDTIME_MCOUNT_SORT
131 bool
132 default y
133 depends on HAVE_BUILDTIME_MCOUNT_SORT && DYNAMIC_FTRACE
134 help
135 Sort the mcount_loc section at build time.
136
137config TRACER_MAX_TRACE
138 bool
139 select TRACER_SNAPSHOT
140
141config TRACE_CLOCK
142 bool
143
144config RING_BUFFER
145 bool
146 select TRACE_CLOCK
147 select IRQ_WORK
148
149config EVENT_TRACING
150 select CONTEXT_SWITCH_TRACER
151 select GLOB
152 bool
153
154config CONTEXT_SWITCH_TRACER
155 bool
156
157config RING_BUFFER_ALLOW_SWAP
158 bool
159 help
160 Allow the use of ring_buffer_swap_cpu.
161 Adds a very slight overhead to tracing when enabled.
162
163config PREEMPTIRQ_TRACEPOINTS
164 bool
165 depends on TRACE_PREEMPT_TOGGLE || TRACE_IRQFLAGS
166 select TRACING
167 default y
168 help
169 Create preempt/irq toggle tracepoints if needed, so that other parts
170 of the kernel can use them to generate or add hooks to them.
171
172# All tracer options should select GENERIC_TRACER. For those options that are
173# enabled by all tracers (context switch and event tracer) they select TRACING.
174# This allows those options to appear when no other tracer is selected. But the
175# options do not appear when something else selects it. We need the two options
176# GENERIC_TRACER and TRACING to avoid circular dependencies to accomplish the
177# hiding of the automatic options.
178
179config TRACING
180 bool
181 select RING_BUFFER
182 select STACKTRACE if STACKTRACE_SUPPORT
183 select TRACEPOINTS
184 select NOP_TRACER
185 select BINARY_PRINTF
186 select EVENT_TRACING
187 select TRACE_CLOCK
188 select NEED_TASKS_RCU
189
190config GENERIC_TRACER
191 bool
192 select TRACING
193
194#
195# Minimum requirements an architecture has to meet for us to
196# be able to offer generic tracing facilities:
197#
198config TRACING_SUPPORT
199 bool
200 depends on TRACE_IRQFLAGS_SUPPORT
201 depends on STACKTRACE_SUPPORT
202 default y
203
204menuconfig FTRACE
205 bool "Tracers"
206 depends on TRACING_SUPPORT
207 default y if DEBUG_KERNEL
208 help
209 Enable the kernel tracing infrastructure.
210
211if FTRACE
212
213config TRACEFS_AUTOMOUNT_DEPRECATED
214 bool "Automount tracefs on debugfs [DEPRECATED]"
215 depends on TRACING
216 default y
217 help
218 The tracing interface was moved from /sys/kernel/debug/tracing
219 to /sys/kernel/tracing in 2015, but the tracing file system
220 was still automounted in /sys/kernel/debug for backward
221 compatibility with tooling.
222
223 The new interface has been around for more than 10 years and
224 the old debug mount will soon be removed.
225
226config BOOTTIME_TRACING
227 bool "Boot-time Tracing support"
228 depends on TRACING
229 select BOOT_CONFIG
230 help
231 Enable developer to setup ftrace subsystem via supplemental
232 kernel cmdline at boot time for debugging (tracing) driver
233 initialization and boot process.
234
235config FUNCTION_TRACER
236 bool "Kernel Function Tracer"
237 depends on HAVE_FUNCTION_TRACER
238 select KALLSYMS
239 select GENERIC_TRACER
240 select CONTEXT_SWITCH_TRACER
241 select GLOB
242 select NEED_TASKS_RCU
243 select TASKS_RUDE_RCU
244 help
245 Enable the kernel to trace every kernel function. This is done
246 by using a compiler feature to insert a small, 5-byte No-Operation
247 instruction at the beginning of every kernel function, which NOP
248 sequence is then dynamically patched into a tracer call when
249 tracing is enabled by the administrator. If it's runtime disabled
250 (the bootup default), then the overhead of the instructions is very
251 small and not measurable even in micro-benchmarks (at least on
252 x86, but may have impact on other architectures).
253
254config FUNCTION_GRAPH_TRACER
255 bool "Kernel Function Graph Tracer"
256 depends on HAVE_FUNCTION_GRAPH_TRACER
257 depends on FUNCTION_TRACER
258 depends on !X86_32 || !CC_OPTIMIZE_FOR_SIZE
259 default y
260 help
261 Enable the kernel to trace a function at both its return
262 and its entry.
263 Its first purpose is to trace the duration of functions and
264 draw a call graph for each thread with some information like
265 the return value. This is done by setting the current return
266 address on the current task structure into a stack of calls.
267
268config FUNCTION_GRAPH_RETVAL
269 bool "Kernel Function Graph Return Value"
270 depends on HAVE_FUNCTION_GRAPH_FREGS
271 depends on FUNCTION_GRAPH_TRACER
272 default n
273 help
274 Support recording and printing the function return value when
275 using function graph tracer. It can be helpful to locate functions
276 that return errors. This feature is off by default, and you can
277 enable it via the trace option funcgraph-retval.
278 See Documentation/trace/ftrace.rst
279
280config FUNCTION_GRAPH_RETADDR
281 bool "Kernel Function Graph Return Address"
282 depends on FUNCTION_GRAPH_TRACER
283 default n
284 help
285 Support recording and printing the function return address when
286 using function graph tracer. It can be helpful to locate code line that
287 the function is called. This feature is off by default, and you can
288 enable it via the trace option funcgraph-retaddr.
289
290config FUNCTION_TRACE_ARGS
291 bool
292 depends on PROBE_EVENTS_BTF_ARGS
293 default y
294 help
295 If supported with function argument access API and BTF, then
296 the function tracer and function graph tracer will support printing
297 of function arguments. This feature is off by default, and can be
298 enabled via the trace option func-args (for the function tracer) and
299 funcgraph-args (for the function graph tracer)
300
301config DYNAMIC_FTRACE
302 bool
303 depends on FUNCTION_TRACER
304 depends on HAVE_DYNAMIC_FTRACE
305 default y
306 help
307 This option will modify all the calls to function tracing
308 dynamically (will patch them out of the binary image and
309 replace them with a No-Op instruction) on boot up. During
310 compile time, a table is made of all the locations that ftrace
311 can function trace, and this table is linked into the kernel
312 image. When this is enabled, functions can be individually
313 enabled, and the functions not enabled will not affect
314 performance of the system.
315
316 See the files in /sys/kernel/tracing:
317 available_filter_functions
318 set_ftrace_filter
319 set_ftrace_notrace
320
321 This way a CONFIG_FUNCTION_TRACER kernel is slightly larger, but
322 otherwise has native performance as long as no tracing is active.
323
324config DYNAMIC_FTRACE_WITH_REGS
325 def_bool y
326 depends on DYNAMIC_FTRACE
327 depends on HAVE_DYNAMIC_FTRACE_WITH_REGS
328
329config DYNAMIC_FTRACE_WITH_DIRECT_CALLS
330 def_bool y
331 depends on DYNAMIC_FTRACE_WITH_REGS || DYNAMIC_FTRACE_WITH_ARGS
332 depends on HAVE_DYNAMIC_FTRACE_WITH_DIRECT_CALLS
333
334config DYNAMIC_FTRACE_WITH_CALL_OPS
335 def_bool y
336 depends on HAVE_DYNAMIC_FTRACE_WITH_CALL_OPS
337
338config DYNAMIC_FTRACE_WITH_ARGS
339 def_bool y
340 depends on DYNAMIC_FTRACE
341 depends on HAVE_DYNAMIC_FTRACE_WITH_ARGS
342
343config DYNAMIC_FTRACE_WITH_JMP
344 def_bool y
345 depends on DYNAMIC_FTRACE
346 depends on DYNAMIC_FTRACE_WITH_DIRECT_CALLS
347 depends on HAVE_DYNAMIC_FTRACE_WITH_JMP
348
349config FUNCTION_SELF_TRACING
350 bool "Function trace tracing code"
351 depends on FUNCTION_TRACER
352 help
353 Normally all the tracing code is set to notrace, where the function
354 tracer will ignore all the tracing functions. Sometimes it is useful
355 for debugging to trace some of the tracing infratructure itself.
356 Enable this to allow some of the tracing infrastructure to be traced
357 by the function tracer. Note, this will likely add noise to function
358 tracing if events and other tracing features are enabled along with
359 function tracing.
360
361 If unsure, say N.
362
363config FPROBE
364 bool "Kernel Function Probe (fprobe)"
365 depends on HAVE_FUNCTION_GRAPH_FREGS && HAVE_FTRACE_GRAPH_FUNC
366 depends on DYNAMIC_FTRACE_WITH_ARGS
367 select FUNCTION_GRAPH_TRACER
368 default n
369 help
370 This option enables kernel function probe (fprobe) based on ftrace.
371 The fprobe is similar to kprobes, but probes only for kernel function
372 entries and exits. This also can probe multiple functions by one
373 fprobe.
374
375 If unsure, say N.
376
377config FUNCTION_PROFILER
378 bool "Kernel function profiler"
379 depends on FUNCTION_TRACER
380 default n
381 help
382 This option enables the kernel function profiler. A file is created
383 in debugfs called function_profile_enabled which defaults to zero.
384 When a 1 is echoed into this file profiling begins, and when a
385 zero is entered, profiling stops. A "functions" file is created in
386 the trace_stat directory; this file shows the list of functions that
387 have been hit and their counters.
388
389 If in doubt, say N.
390
391config STACK_TRACER
392 bool "Trace max stack"
393 depends on HAVE_FUNCTION_TRACER
394 select FUNCTION_TRACER
395 select STACKTRACE
396 select KALLSYMS
397 help
398 This special tracer records the maximum stack footprint of the
399 kernel and displays it in /sys/kernel/tracing/stack_trace.
400
401 This tracer works by hooking into every function call that the
402 kernel executes, and keeping a maximum stack depth value and
403 stack-trace saved. If this is configured with DYNAMIC_FTRACE
404 then it will not have any overhead while the stack tracer
405 is disabled.
406
407 To enable the stack tracer on bootup, pass in 'stacktrace'
408 on the kernel command line.
409
410 The stack tracer can also be enabled or disabled via the
411 sysctl kernel.stack_tracer_enabled
412
413 Say N if unsure.
414
415config TRACE_PREEMPT_TOGGLE
416 bool
417 help
418 Enables hooks which will be called when preemption is first disabled,
419 and last enabled.
420
421config IRQSOFF_TRACER
422 bool "Interrupts-off Latency Tracer"
423 default n
424 depends on TRACE_IRQFLAGS_SUPPORT
425 select TRACE_IRQFLAGS
426 select GENERIC_TRACER
427 select TRACER_MAX_TRACE
428 select RING_BUFFER_ALLOW_SWAP
429 select TRACER_SNAPSHOT_PER_CPU_SWAP
430 help
431 This option measures the time spent in irqs-off critical
432 sections, with microsecond accuracy.
433
434 The default measurement method is a maximum search, which is
435 disabled by default and can be runtime (re-)started
436 via:
437
438 echo 0 > /sys/kernel/tracing/tracing_max_latency
439
440 (Note that kernel size and overhead increase with this option
441 enabled. This option and the preempt-off timing option can be
442 used together or separately.)
443
444config PREEMPT_TRACER
445 bool "Preemption-off Latency Tracer"
446 default n
447 depends on PREEMPTION
448 select GENERIC_TRACER
449 select TRACER_MAX_TRACE
450 select RING_BUFFER_ALLOW_SWAP
451 select TRACER_SNAPSHOT_PER_CPU_SWAP
452 select TRACE_PREEMPT_TOGGLE
453 help
454 This option measures the time spent in preemption-off critical
455 sections, with microsecond accuracy.
456
457 The default measurement method is a maximum search, which is
458 disabled by default and can be runtime (re-)started
459 via:
460
461 echo 0 > /sys/kernel/tracing/tracing_max_latency
462
463 (Note that kernel size and overhead increase with this option
464 enabled. This option and the irqs-off timing option can be
465 used together or separately.)
466
467config SCHED_TRACER
468 bool "Scheduling Latency Tracer"
469 select GENERIC_TRACER
470 select CONTEXT_SWITCH_TRACER
471 select TRACER_MAX_TRACE
472 help
473 This tracer tracks the latency of the highest priority task
474 to be scheduled in, starting from the point it has woken up.
475
476config HWLAT_TRACER
477 bool "Tracer to detect hardware latencies (like SMIs)"
478 select GENERIC_TRACER
479 select TRACER_MAX_TRACE
480 help
481 This tracer, when enabled will create one or more kernel threads,
482 depending on what the cpumask file is set to, which each thread
483 spinning in a loop looking for interruptions caused by
484 something other than the kernel. For example, if a
485 System Management Interrupt (SMI) takes a noticeable amount of
486 time, this tracer will detect it. This is useful for testing
487 if a system is reliable for Real Time tasks.
488
489 Some files are created in the tracing directory when this
490 is enabled:
491
492 hwlat_detector/width - time in usecs for how long to spin for
493 hwlat_detector/window - time in usecs between the start of each
494 iteration
495
496 A kernel thread is created that will spin with interrupts disabled
497 for "width" microseconds in every "window" cycle. It will not spin
498 for "window - width" microseconds, where the system can
499 continue to operate.
500
501 The output will appear in the trace and trace_pipe files.
502
503 When the tracer is not running, it has no affect on the system,
504 but when it is running, it can cause the system to be
505 periodically non responsive. Do not run this tracer on a
506 production system.
507
508 To enable this tracer, echo in "hwlat" into the current_tracer
509 file. Every time a latency is greater than tracing_thresh, it will
510 be recorded into the ring buffer.
511
512config OSNOISE_TRACER
513 bool "OS Noise tracer"
514 select GENERIC_TRACER
515 select TRACER_MAX_TRACE
516 help
517 In the context of high-performance computing (HPC), the Operating
518 System Noise (osnoise) refers to the interference experienced by an
519 application due to activities inside the operating system. In the
520 context of Linux, NMIs, IRQs, SoftIRQs, and any other system thread
521 can cause noise to the system. Moreover, hardware-related jobs can
522 also cause noise, for example, via SMIs.
523
524 The osnoise tracer leverages the hwlat_detector by running a similar
525 loop with preemption, SoftIRQs and IRQs enabled, thus allowing all
526 the sources of osnoise during its execution. The osnoise tracer takes
527 note of the entry and exit point of any source of interferences,
528 increasing a per-cpu interference counter. It saves an interference
529 counter for each source of interference. The interference counter for
530 NMI, IRQs, SoftIRQs, and threads is increased anytime the tool
531 observes these interferences' entry events. When a noise happens
532 without any interference from the operating system level, the
533 hardware noise counter increases, pointing to a hardware-related
534 noise. In this way, osnoise can account for any source of
535 interference. At the end of the period, the osnoise tracer prints
536 the sum of all noise, the max single noise, the percentage of CPU
537 available for the thread, and the counters for the noise sources.
538
539 In addition to the tracer, a set of tracepoints were added to
540 facilitate the identification of the osnoise source.
541
542 The output will appear in the trace and trace_pipe files.
543
544 To enable this tracer, echo in "osnoise" into the current_tracer
545 file.
546
547config TIMERLAT_TRACER
548 bool "Timerlat tracer"
549 select OSNOISE_TRACER
550 select GENERIC_TRACER
551 help
552 The timerlat tracer aims to help the preemptive kernel developers
553 to find sources of wakeup latencies of real-time threads.
554
555 The tracer creates a per-cpu kernel thread with real-time priority.
556 The tracer thread sets a periodic timer to wakeup itself, and goes
557 to sleep waiting for the timer to fire. At the wakeup, the thread
558 then computes a wakeup latency value as the difference between
559 the current time and the absolute time that the timer was set
560 to expire.
561
562 The tracer prints two lines at every activation. The first is the
563 timer latency observed at the hardirq context before the
564 activation of the thread. The second is the timer latency observed
565 by the thread, which is the same level that cyclictest reports. The
566 ACTIVATION ID field serves to relate the irq execution to its
567 respective thread execution.
568
569 The tracer is build on top of osnoise tracer, and the osnoise:
570 events can be used to trace the source of interference from NMI,
571 IRQs and other threads. It also enables the capture of the
572 stacktrace at the IRQ context, which helps to identify the code
573 path that can cause thread delay.
574
575config MMIOTRACE
576 bool "Memory mapped IO tracing"
577 depends on HAVE_MMIOTRACE_SUPPORT && PCI
578 select GENERIC_TRACER
579 help
580 Mmiotrace traces Memory Mapped I/O access and is meant for
581 debugging and reverse engineering. It is called from the ioremap
582 implementation and works via page faults. Tracing is disabled by
583 default and can be enabled at run-time.
584
585 See Documentation/trace/mmiotrace.rst.
586 If you are not helping to develop drivers, say N.
587
588config ENABLE_DEFAULT_TRACERS
589 bool "Trace process context switches and events"
590 depends on !GENERIC_TRACER
591 select TRACING
592 help
593 This tracer hooks to various trace points in the kernel,
594 allowing the user to pick and choose which trace point they
595 want to trace. It also includes the sched_switch tracer plugin.
596
597config FTRACE_SYSCALLS
598 bool "Trace syscalls"
599 depends on HAVE_SYSCALL_TRACEPOINTS
600 select GENERIC_TRACER
601 select KALLSYMS
602 help
603 Basic tracer to catch the syscall entry and exit events.
604
605config TRACE_SYSCALL_BUF_SIZE_DEFAULT
606 int "System call user read max size"
607 range 0 165
608 default 63
609 depends on FTRACE_SYSCALLS
610 help
611 Some system call trace events will record the data from a user
612 space address that one of the parameters point to. The amount of
613 data per event is limited. That limit is set by this config and
614 this config also affects how much user space data perf can read.
615
616 For a tracing instance, this size may be changed by writing into
617 its syscall_user_buf_size file.
618
619config TRACER_SNAPSHOT
620 bool "Create a snapshot trace buffer"
621 help
622 Allow tracing users to take snapshot of the current buffer using the
623 ftrace interface, e.g.:
624
625 echo 1 > /sys/kernel/tracing/snapshot
626 cat snapshot
627
628 Note, the latency tracers select this option. To disable it,
629 all the latency tracers need to be disabled.
630
631config TRACER_SNAPSHOT_PER_CPU_SWAP
632 bool "Allow snapshot to swap per CPU"
633 depends on TRACER_SNAPSHOT
634 select RING_BUFFER_ALLOW_SWAP
635 help
636 Allow doing a snapshot of a single CPU buffer instead of a
637 full swap (all buffers). If this is set, then the following is
638 allowed:
639
640 echo 1 > /sys/kernel/tracing/per_cpu/cpu2/snapshot
641
642 After which, only the tracing buffer for CPU 2 was swapped with
643 the main tracing buffer, and the other CPU buffers remain the same.
644
645 When this is enabled, this adds a little more overhead to the
646 trace recording, as it needs to add some checks to synchronize
647 recording with swaps. But this does not affect the performance
648 of the overall system. This is enabled by default when the preempt
649 or irq latency tracers are enabled, as those need to swap as well
650 and already adds the overhead (plus a lot more).
651
652config TRACE_BRANCH_PROFILING
653 bool
654 select GENERIC_TRACER
655
656choice
657 prompt "Branch Profiling"
658 default BRANCH_PROFILE_NONE
659 help
660 The branch profiling is a software profiler. It will add hooks
661 into the C conditionals to test which path a branch takes.
662
663 The likely/unlikely profiler only looks at the conditions that
664 are annotated with a likely or unlikely macro.
665
666 The "all branch" profiler will profile every if-statement in the
667 kernel. This profiler will also enable the likely/unlikely
668 profiler.
669
670 Either of the above profilers adds a bit of overhead to the system.
671 If unsure, choose "No branch profiling".
672
673config BRANCH_PROFILE_NONE
674 bool "No branch profiling"
675 help
676 No branch profiling. Branch profiling adds a bit of overhead.
677 Only enable it if you want to analyse the branching behavior.
678 Otherwise keep it disabled.
679
680config PROFILE_ANNOTATED_BRANCHES
681 bool "Trace likely/unlikely profiler"
682 select TRACE_BRANCH_PROFILING
683 help
684 This tracer profiles all likely and unlikely macros
685 in the kernel. It will display the results in:
686
687 /sys/kernel/tracing/trace_stat/branch_annotated
688
689 Note: this will add a significant overhead; only turn this
690 on if you need to profile the system's use of these macros.
691
692config PROFILE_ALL_BRANCHES
693 bool "Profile all if conditionals" if !FORTIFY_SOURCE
694 select TRACE_BRANCH_PROFILING
695 help
696 This tracer profiles all branch conditions. Every if ()
697 taken in the kernel is recorded whether it hit or miss.
698 The results will be displayed in:
699
700 /sys/kernel/tracing/trace_stat/branch_all
701
702 This option also enables the likely/unlikely profiler.
703
704 This configuration, when enabled, will impose a great overhead
705 on the system. This should only be enabled when the system
706 is to be analyzed in much detail.
707endchoice
708
709config TRACING_BRANCHES
710 bool
711 help
712 Selected by tracers that will trace the likely and unlikely
713 conditions. This prevents the tracers themselves from being
714 profiled. Profiling the tracing infrastructure can only happen
715 when the likelys and unlikelys are not being traced.
716
717config BRANCH_TRACER
718 bool "Trace likely/unlikely instances"
719 depends on TRACE_BRANCH_PROFILING
720 select TRACING_BRANCHES
721 help
722 This traces the events of likely and unlikely condition
723 calls in the kernel. The difference between this and the
724 "Trace likely/unlikely profiler" is that this is not a
725 histogram of the callers, but actually places the calling
726 events into a running trace buffer to see when and where the
727 events happened, as well as their results.
728
729 Say N if unsure.
730
731config BLK_DEV_IO_TRACE
732 bool "Support for tracing block IO actions"
733 depends on SYSFS
734 depends on BLOCK
735 select RELAY
736 select DEBUG_FS
737 select TRACEPOINTS
738 select GENERIC_TRACER
739 select STACKTRACE
740 help
741 Say Y here if you want to be able to trace the block layer actions
742 on a given queue. Tracing allows you to see any traffic happening
743 on a block device queue. For more information (and the userspace
744 support tools needed), fetch the blktrace tools from:
745
746 git://git.kernel.dk/blktrace.git
747
748 Tracing also is possible using the ftrace interface, e.g.:
749
750 echo 1 > /sys/block/sda/sda1/trace/enable
751 echo blk > /sys/kernel/tracing/current_tracer
752 cat /sys/kernel/tracing/trace_pipe
753
754 If unsure, say N.
755
756config FPROBE_EVENTS
757 depends on FPROBE
758 depends on HAVE_REGS_AND_STACK_ACCESS_API
759 bool "Enable fprobe-based dynamic events"
760 select TRACING
761 select PROBE_EVENTS
762 select DYNAMIC_EVENTS
763 default y
764 help
765 This allows user to add tracing events on the function entry and
766 exit via ftrace interface. The syntax is same as the kprobe events
767 and the kprobe events on function entry and exit will be
768 transparently converted to this fprobe events.
769
770config PROBE_EVENTS_BTF_ARGS
771 depends on HAVE_FUNCTION_ARG_ACCESS_API
772 depends on FPROBE_EVENTS || KPROBE_EVENTS
773 depends on DEBUG_INFO_BTF && BPF_SYSCALL
774 bool "Support BTF function arguments for probe events"
775 default y
776 help
777 The user can specify the arguments of the probe event using the names
778 of the arguments of the probed function, when the probe location is a
779 kernel function entry or a tracepoint.
780 This is available only if BTF (BPF Type Format) support is enabled.
781
782config PROBE_EVENTS_DUMP_FETCHARG
783 bool "Dump of dynamic probe event fetch-arguments"
784 depends on PROBE_EVENTS
785 default n
786 help
787 This shows the dump of fetch-arguments of dynamic probe events
788 alongside their event definitions in the dynamic_events file
789 as comment lines. This is useful to debug the probe events.
790 Since this exposes the raw values in the dynamic_events file,
791 it might be a security risk. Only enable it if you need to debug
792 probe events themselves.
793
794config KPROBE_EVENTS
795 depends on KPROBES
796 depends on HAVE_REGS_AND_STACK_ACCESS_API
797 bool "Enable kprobes-based dynamic events"
798 select TRACING
799 select PROBE_EVENTS
800 select DYNAMIC_EVENTS
801 default y
802 help
803 This allows the user to add tracing events (similar to tracepoints)
804 on the fly via the ftrace interface. See
805 Documentation/trace/kprobetrace.rst for more details.
806
807 Those events can be inserted wherever kprobes can probe, and record
808 various register and memory values.
809
810 This option is also required by perf-probe subcommand of perf tools.
811 If you want to use perf tools, this option is strongly recommended.
812
813config KPROBE_EVENTS_ON_NOTRACE
814 bool "Do NOT protect notrace function from kprobe events"
815 depends on KPROBE_EVENTS
816 depends on DYNAMIC_FTRACE
817 default n
818 help
819 This is only for the developers who want to debug ftrace itself
820 using kprobe events.
821
822 If kprobes can use ftrace instead of breakpoint, ftrace related
823 functions are protected from kprobe-events to prevent an infinite
824 recursion or any unexpected execution path which leads to a kernel
825 crash.
826
827 This option disables such protection and allows you to put kprobe
828 events on ftrace functions for debugging ftrace by itself.
829 Note that this might let you shoot yourself in the foot.
830
831 If unsure, say N.
832
833config UPROBE_EVENTS
834 bool "Enable uprobes-based dynamic events"
835 depends on ARCH_SUPPORTS_UPROBES
836 depends on MMU
837 depends on PERF_EVENTS
838 select UPROBES
839 select PROBE_EVENTS
840 select DYNAMIC_EVENTS
841 select TRACING
842 default y
843 help
844 This allows the user to add tracing events on top of userspace
845 dynamic events (similar to tracepoints) on the fly via the trace
846 events interface. Those events can be inserted wherever uprobes
847 can probe, and record various registers.
848 This option is required if you plan to use perf-probe subcommand
849 of perf tools on user space applications.
850
851config EPROBE_EVENTS
852 bool "Enable event-based dynamic events"
853 depends on TRACING
854 depends on HAVE_REGS_AND_STACK_ACCESS_API
855 select PROBE_EVENTS
856 select DYNAMIC_EVENTS
857 default y
858 help
859 Eprobes are dynamic events that can be placed on other existing
860 events. It can be used to limit what fields are recorded in
861 an event or even dereference a field of an event. It can
862 convert the type of an event field. For example, turn an
863 address into a string.
864
865config BPF_EVENTS
866 depends on BPF_SYSCALL
867 depends on (KPROBE_EVENTS || UPROBE_EVENTS) && PERF_EVENTS
868 bool
869 default y
870 help
871 This allows the user to attach BPF programs to kprobe, uprobe, and
872 tracepoint events.
873
874config DYNAMIC_EVENTS
875 def_bool n
876
877config PROBE_EVENTS
878 def_bool n
879
880config BPF_KPROBE_OVERRIDE
881 bool "Enable BPF programs to override a kprobed function"
882 depends on BPF_EVENTS
883 depends on FUNCTION_ERROR_INJECTION
884 default n
885 help
886 Allows BPF to override the execution of a probed function and
887 set a different return value. This is used for error injection.
888
889config FTRACE_MCOUNT_USE_PATCHABLE_FUNCTION_ENTRY
890 bool
891 depends on DYNAMIC_FTRACE
892
893config FTRACE_MCOUNT_USE_CC
894 def_bool y
895 depends on $(cc-option,-mrecord-mcount)
896 depends on !FTRACE_MCOUNT_USE_PATCHABLE_FUNCTION_ENTRY
897 depends on DYNAMIC_FTRACE
898
899config FTRACE_MCOUNT_USE_OBJTOOL
900 def_bool y
901 depends on HAVE_OBJTOOL_MCOUNT
902 depends on !FTRACE_MCOUNT_USE_PATCHABLE_FUNCTION_ENTRY
903 depends on !FTRACE_MCOUNT_USE_CC
904 depends on DYNAMIC_FTRACE
905 select OBJTOOL
906
907config FTRACE_MCOUNT_USE_RECORDMCOUNT
908 def_bool y
909 depends on !FTRACE_MCOUNT_USE_PATCHABLE_FUNCTION_ENTRY
910 depends on !FTRACE_MCOUNT_USE_CC
911 depends on !FTRACE_MCOUNT_USE_OBJTOOL
912 depends on DYNAMIC_FTRACE
913
914config TRACING_MAP
915 bool
916 depends on ARCH_HAVE_NMI_SAFE_CMPXCHG
917 help
918 tracing_map is a special-purpose lock-free map for tracing,
919 separated out as a stand-alone facility in order to allow it
920 to be shared between multiple tracers. It isn't meant to be
921 generally used outside of that context, and is normally
922 selected by tracers that use it.
923
924config SYNTH_EVENTS
925 bool "Synthetic trace events"
926 select TRACING
927 select DYNAMIC_EVENTS
928 default n
929 help
930 Synthetic events are user-defined trace events that can be
931 used to combine data from other trace events or in fact any
932 data source. Synthetic events can be generated indirectly
933 via the trace() action of histogram triggers or directly
934 by way of an in-kernel API.
935
936 See Documentation/trace/events.rst or
937 Documentation/trace/histogram.rst for details and examples.
938
939 If in doubt, say N.
940
941config USER_EVENTS
942 bool "User trace events"
943 select TRACING
944 select DYNAMIC_EVENTS
945 help
946 User trace events are user-defined trace events that
947 can be used like an existing kernel trace event. User trace
948 events are generated by writing to a tracefs file. User
949 processes can determine if their tracing events should be
950 generated by registering a value and bit with the kernel
951 that reflects when it is enabled or not.
952
953 See Documentation/trace/user_events.rst.
954 If in doubt, say N.
955
956config HIST_TRIGGERS
957 bool "Histogram triggers"
958 depends on ARCH_HAVE_NMI_SAFE_CMPXCHG
959 select TRACING_MAP
960 select TRACING
961 select DYNAMIC_EVENTS
962 select SYNTH_EVENTS
963 default n
964 help
965 Hist triggers allow one or more arbitrary trace event fields
966 to be aggregated into hash tables and dumped to stdout by
967 reading a debugfs/tracefs file. They're useful for
968 gathering quick and dirty (though precise) summaries of
969 event activity as an initial guide for further investigation
970 using more advanced tools.
971
972 Inter-event tracing of quantities such as latencies is also
973 supported using hist triggers under this option.
974
975 See Documentation/trace/histogram.rst.
976 If in doubt, say N.
977
978config TRACE_EVENT_INJECT
979 bool "Trace event injection"
980 depends on TRACING
981 help
982 Allow user-space to inject a specific trace event into the ring
983 buffer. This is mainly used for testing purpose.
984
985 If unsure, say N.
986
987config TRACEPOINT_BENCHMARK
988 bool "Add tracepoint that benchmarks tracepoints"
989 help
990 This option creates the tracepoint "benchmark:benchmark_event".
991 When the tracepoint is enabled, it kicks off a kernel thread that
992 goes into an infinite loop (calling cond_resched() to let other tasks
993 run), and calls the tracepoint. Each iteration will record the time
994 it took to write to the tracepoint and the next iteration that
995 data will be passed to the tracepoint itself. That is, the tracepoint
996 will report the time it took to do the previous tracepoint.
997 The string written to the tracepoint is a static string of 128 bytes
998 to keep the time the same. The initial string is simply a write of
999 "START". The second string records the cold cache time of the first
1000 write which is not added to the rest of the calculations.
1001
1002 As it is a tight loop, it benchmarks as hot cache. That's fine because
1003 we care most about hot paths that are probably in cache already.
1004
1005 An example of the output:
1006
1007 START
1008 first=3672 [COLD CACHED]
1009 last=632 first=3672 max=632 min=632 avg=316 std=446 std^2=199712
1010 last=278 first=3672 max=632 min=278 avg=303 std=316 std^2=100337
1011 last=277 first=3672 max=632 min=277 avg=296 std=258 std^2=67064
1012 last=273 first=3672 max=632 min=273 avg=292 std=224 std^2=50411
1013 last=273 first=3672 max=632 min=273 avg=288 std=200 std^2=40389
1014 last=281 first=3672 max=632 min=273 avg=287 std=183 std^2=33666
1015
1016
1017config RING_BUFFER_BENCHMARK
1018 tristate "Ring buffer benchmark stress tester"
1019 depends on RING_BUFFER
1020 help
1021 This option creates a test to stress the ring buffer and benchmark it.
1022 It creates its own ring buffer such that it will not interfere with
1023 any other users of the ring buffer (such as ftrace). It then creates
1024 a producer and consumer that will run for 10 seconds and sleep for
1025 10 seconds. Each interval it will print out the number of events
1026 it recorded and give a rough estimate of how long each iteration took.
1027
1028 It does not disable interrupts or raise its priority, so it may be
1029 affected by processes that are running.
1030
1031 If unsure, say N.
1032
1033config TRACE_EVAL_MAP_FILE
1034 bool "Show eval mappings for trace events"
1035 depends on TRACING
1036 help
1037 The "print fmt" of the trace events will show the enum/sizeof names
1038 instead of their values. This can cause problems for user space tools
1039 that use this string to parse the raw data as user space does not know
1040 how to convert the string to its value.
1041
1042 To fix this, there's a special macro in the kernel that can be used
1043 to convert an enum/sizeof into its value. If this macro is used, then
1044 the print fmt strings will be converted to their values.
1045
1046 If something does not get converted properly, this option can be
1047 used to show what enums/sizeof the kernel tried to convert.
1048
1049 This option is for debugging the conversions. A file is created
1050 in the tracing directory called "eval_map" that will show the
1051 names matched with their values and what trace event system they
1052 belong too.
1053
1054 Normally, the mapping of the strings to values will be freed after
1055 boot up or module load. With this option, they will not be freed, as
1056 they are needed for the "eval_map" file. Enabling this option will
1057 increase the memory footprint of the running kernel.
1058
1059 If unsure, say N.
1060
1061config FTRACE_RECORD_RECURSION
1062 bool "Record functions that recurse in function tracing"
1063 depends on FUNCTION_TRACER
1064 help
1065 All callbacks that attach to the function tracing have some sort
1066 of protection against recursion. Even though the protection exists,
1067 it adds overhead. This option will create a file in the tracefs
1068 file system called "recursed_functions" that will list the functions
1069 that triggered a recursion.
1070
1071 This will add more overhead to cases that have recursion.
1072
1073 If unsure, say N
1074
1075config FTRACE_RECORD_RECURSION_SIZE
1076 int "Max number of recursed functions to record"
1077 default 128
1078 depends on FTRACE_RECORD_RECURSION
1079 help
1080 This defines the limit of number of functions that can be
1081 listed in the "recursed_functions" file, that lists all
1082 the functions that caused a recursion to happen.
1083 This file can be reset, but the limit can not change in
1084 size at runtime.
1085
1086config FTRACE_VALIDATE_RCU_IS_WATCHING
1087 bool "Validate RCU is on during ftrace execution"
1088 depends on FUNCTION_TRACER
1089 depends on ARCH_WANTS_NO_INSTR
1090 help
1091 All callbacks that attach to the function tracing have some sort of
1092 protection against recursion. This option is only to verify that
1093 ftrace (and other users of ftrace_test_recursion_trylock()) are not
1094 called outside of RCU, as if they are, it can cause a race. But it
1095 also has a noticeable overhead when enabled.
1096
1097 If unsure, say N
1098
1099config RING_BUFFER_RECORD_RECURSION
1100 bool "Record functions that recurse in the ring buffer"
1101 depends on FTRACE_RECORD_RECURSION
1102 # default y, because it is coupled with FTRACE_RECORD_RECURSION
1103 default y
1104 help
1105 The ring buffer has its own internal recursion. Although when
1106 recursion happens it won't cause harm because of the protection,
1107 but it does cause unwanted overhead. Enabling this option will
1108 place where recursion was detected into the ftrace "recursed_functions"
1109 file.
1110
1111 This will add more overhead to cases that have recursion.
1112
1113config GCOV_PROFILE_FTRACE
1114 bool "Enable GCOV profiling on ftrace subsystem"
1115 depends on GCOV_KERNEL
1116 help
1117 Enable GCOV profiling on ftrace subsystem for checking
1118 which functions/lines are tested.
1119
1120 If unsure, say N.
1121
1122 Note that on a kernel compiled with this config, ftrace will
1123 run significantly slower.
1124
1125config FTRACE_SELFTEST
1126 bool
1127
1128config FTRACE_STARTUP_TEST
1129 bool "Perform a startup test on ftrace"
1130 depends on GENERIC_TRACER
1131 select FTRACE_SELFTEST
1132 help
1133 This option performs a series of startup tests on ftrace. On bootup
1134 a series of tests are made to verify that the tracer is
1135 functioning properly. It will do tests on all the configured
1136 tracers of ftrace.
1137
1138config EVENT_TRACE_STARTUP_TEST
1139 bool "Run selftest on trace events"
1140 depends on FTRACE_STARTUP_TEST
1141 default y
1142 help
1143 This option performs a test on all trace events in the system.
1144 It basically just enables each event and runs some code that
1145 will trigger events (not necessarily the event it enables)
1146 This may take some time run as there are a lot of events.
1147
1148config EVENT_TRACE_TEST_SYSCALLS
1149 bool "Run selftest on syscall events"
1150 depends on EVENT_TRACE_STARTUP_TEST
1151 help
1152 This option will also enable testing every syscall event.
1153 It only enables the event and disables it and runs various loads
1154 with the event enabled. This adds a bit more time for kernel boot
1155 up since it runs this on every system call defined.
1156
1157 TBD - enable a way to actually call the syscalls as we test their
1158 events
1159
1160config FTRACE_SORT_STARTUP_TEST
1161 bool "Verify compile time sorting of ftrace functions"
1162 depends on DYNAMIC_FTRACE
1163 depends on BUILDTIME_MCOUNT_SORT
1164 help
1165 Sorting of the mcount_loc sections that is used to find the
1166 where the ftrace knows where to patch functions for tracing
1167 and other callbacks is done at compile time. But if the sort
1168 is not done correctly, it will cause non-deterministic failures.
1169 When this is set, the sorted sections will be verified that they
1170 are in deed sorted and will warn if they are not.
1171
1172 If unsure, say N
1173
1174config RING_BUFFER_STARTUP_TEST
1175 bool "Ring buffer startup self test"
1176 depends on RING_BUFFER
1177 help
1178 Run a simple self test on the ring buffer on boot up. Late in the
1179 kernel boot sequence, the test will start that kicks off
1180 a thread per cpu. Each thread will write various size events
1181 into the ring buffer. Another thread is created to send IPIs
1182 to each of the threads, where the IPI handler will also write
1183 to the ring buffer, to test/stress the nesting ability.
1184 If any anomalies are discovered, a warning will be displayed
1185 and all ring buffers will be disabled.
1186
1187 The test runs for 10 seconds. This will slow your boot time
1188 by at least 10 more seconds.
1189
1190 At the end of the test, statistics and more checks are done.
1191 It will output the stats of each per cpu buffer: What
1192 was written, the sizes, what was read, what was lost, and
1193 other similar details.
1194
1195 If unsure, say N
1196
1197config RING_BUFFER_VALIDATE_TIME_DELTAS
1198 bool "Verify ring buffer time stamp deltas"
1199 depends on RING_BUFFER
1200 help
1201 This will audit the time stamps on the ring buffer sub
1202 buffer to make sure that all the time deltas for the
1203 events on a sub buffer matches the current time stamp.
1204 This audit is performed for every event that is not
1205 interrupted, or interrupting another event. A check
1206 is also made when traversing sub buffers to make sure
1207 that all the deltas on the previous sub buffer do not
1208 add up to be greater than the current time stamp.
1209
1210 NOTE: This adds significant overhead to recording of events,
1211 and should only be used to test the logic of the ring buffer.
1212 Do not use it on production systems.
1213
1214 Only say Y if you understand what this does, and you
1215 still want it enabled. Otherwise say N
1216
1217config RING_BUFFER_PERSISTENT_INJECT
1218 bool "Enable persistent ring buffer error injection test"
1219 depends on RING_BUFFER
1220 help
1221 This option will have the kernel check if the persistent ring
1222 buffer is named "ptracingtest". and if so, it will corrupt some
1223 of its pages on a kernel panic. This is used to test if the
1224 persistent ring buffer can recover from some of its sub-buffers
1225 being corrupted.
1226 To use this, boot a kernel with a "ptracingtest" persistent
1227 ring buffer, e.g.
1228
1229 reserve_mem=20M:2M:trace trace_instance=ptracingtest@trace panic=1
1230
1231 And after the 1st boot, run the following commands:
1232
1233 cd /sys/kernel/tracing/instances/ptracingtest
1234 echo 1 > events/enable
1235 echo 1 > tracing_on
1236 sleep 3
1237 echo c > /proc/sysrq-trigger
1238
1239 After the panic message, the kernel will reboot and will show
1240 the test results in the console output.
1241
1242 Note that events for the test ring buffer needs to be enabled
1243 prior to crashing the kernel so that the ring buffer has content
1244 that the test will corrupt.
1245 As the test will corrupt events in the "ptracingtest" persistent
1246 ring buffer, it should not be used for any other purpose other
1247 than this test.
1248
1249 If unsure, say N
1250
1251config MMIOTRACE_TEST
1252 tristate "Test module for mmiotrace"
1253 depends on MMIOTRACE && m
1254 help
1255 This is a dumb module for testing mmiotrace. It is very dangerous
1256 as it will write garbage to IO memory starting at a given address.
1257 However, it should be safe to use on e.g. unused portion of VRAM.
1258
1259 Say N, unless you absolutely know what you are doing.
1260
1261config PREEMPTIRQ_DELAY_TEST
1262 tristate "Test module to create a preempt / IRQ disable delay thread to test latency tracers"
1263 depends on m
1264 help
1265 Select this option to build a test module that can help test latency
1266 tracers by executing a preempt or irq disable section with a user
1267 configurable delay. The module busy waits for the duration of the
1268 critical section.
1269
1270 For example, the following invocation generates a burst of three
1271 irq-disabled critical sections for 500us:
1272 modprobe preemptirq_delay_test test_mode=irq delay=500 burst_size=3
1273
1274 What's more, if you want to attach the test on the cpu which the latency
1275 tracer is running on, specify cpu_affinity=cpu_num at the end of the
1276 command.
1277
1278 If unsure, say N
1279
1280config SYNTH_EVENT_GEN_TEST
1281 tristate "Test module for in-kernel synthetic event generation"
1282 depends on SYNTH_EVENTS && m
1283 help
1284 This option creates a test module to check the base
1285 functionality of in-kernel synthetic event definition and
1286 generation.
1287
1288 To test, insert the module, and then check the trace buffer
1289 for the generated sample events.
1290
1291 If unsure, say N.
1292
1293config KPROBE_EVENT_GEN_TEST
1294 tristate "Test module for in-kernel kprobe event generation"
1295 depends on KPROBE_EVENTS && m
1296 help
1297 This option creates a test module to check the base
1298 functionality of in-kernel kprobe event definition.
1299
1300 To test, insert the module, and then check the trace buffer
1301 for the generated kprobe events.
1302
1303 If unsure, say N.
1304
1305config HIST_TRIGGERS_DEBUG
1306 bool "Hist trigger debug support"
1307 depends on HIST_TRIGGERS
1308 help
1309 Add "hist_debug" file for each event, which when read will
1310 dump out a bunch of internal details about the hist triggers
1311 defined on that event.
1312
1313 The hist_debug file serves a couple of purposes:
1314
1315 - Helps developers verify that nothing is broken.
1316
1317 - Provides educational information to support the details
1318 of the hist trigger internals as described by
1319 Documentation/trace/histogram-design.rst.
1320
1321 The hist_debug output only covers the data structures
1322 related to the histogram definitions themselves and doesn't
1323 display the internals of map buckets or variable values of
1324 running histograms.
1325
1326 If unsure, say N.
1327
1328source "kernel/trace/rv/Kconfig"
1329
1330config TRACE_REMOTE
1331 bool
1332
1333config SIMPLE_RING_BUFFER
1334 bool
1335
1336config TRACE_REMOTE_TEST
1337 tristate "Test module for remote tracing"
1338 select TRACE_REMOTE
1339 select SIMPLE_RING_BUFFER
1340 help
1341 This trace remote includes a ring-buffer writer implementation using
1342 "simple_ring_buffer". This is solely intending for testing.
1343
1344endif # FTRACE