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