0001 # SPDX-License-Identifier: GPL-2.0-only
0002 #
0003 # Architectures that offer an FUNCTION_TRACER implementation should
0004 # select HAVE_FUNCTION_TRACER:
0005 #
0006
0007 config USER_STACKTRACE_SUPPORT
0008 bool
0009
0010 config NOP_TRACER
0011 bool
0012
0013 config HAVE_RETHOOK
0014 bool
0015
0016 config RETHOOK
0017 bool
0018 depends on HAVE_RETHOOK
0019 help
0020 Enable generic return hooking feature. This is an internal
0021 API, which will be used by other function-entry hooking
0022 features like fprobe and kprobes.
0023
0024 config HAVE_FUNCTION_TRACER
0025 bool
0026 help
0027 See Documentation/trace/ftrace-design.rst
0028
0029 config HAVE_FUNCTION_GRAPH_TRACER
0030 bool
0031 help
0032 See Documentation/trace/ftrace-design.rst
0033
0034 config HAVE_DYNAMIC_FTRACE
0035 bool
0036 help
0037 See Documentation/trace/ftrace-design.rst
0038
0039 config HAVE_DYNAMIC_FTRACE_WITH_REGS
0040 bool
0041
0042 config HAVE_DYNAMIC_FTRACE_WITH_DIRECT_CALLS
0043 bool
0044
0045 config HAVE_DYNAMIC_FTRACE_WITH_ARGS
0046 bool
0047 help
0048 If this is set, then arguments and stack can be found from
0049 the pt_regs passed into the function callback regs parameter
0050 by default, even without setting the REGS flag in the ftrace_ops.
0051 This allows for use of regs_get_kernel_argument() and
0052 kernel_stack_pointer().
0053
0054 config HAVE_FTRACE_MCOUNT_RECORD
0055 bool
0056 help
0057 See Documentation/trace/ftrace-design.rst
0058
0059 config HAVE_SYSCALL_TRACEPOINTS
0060 bool
0061 help
0062 See Documentation/trace/ftrace-design.rst
0063
0064 config HAVE_FENTRY
0065 bool
0066 help
0067 Arch supports the gcc options -pg with -mfentry
0068
0069 config HAVE_NOP_MCOUNT
0070 bool
0071 help
0072 Arch supports the gcc options -pg with -mrecord-mcount and -nop-mcount
0073
0074 config HAVE_OBJTOOL_MCOUNT
0075 bool
0076 help
0077 Arch supports objtool --mcount
0078
0079 config HAVE_C_RECORDMCOUNT
0080 bool
0081 help
0082 C version of recordmcount available?
0083
0084 config HAVE_BUILDTIME_MCOUNT_SORT
0085 bool
0086 help
0087 An architecture selects this if it sorts the mcount_loc section
0088 at build time.
0089
0090 config BUILDTIME_MCOUNT_SORT
0091 bool
0092 default y
0093 depends on HAVE_BUILDTIME_MCOUNT_SORT && DYNAMIC_FTRACE
0094 help
0095 Sort the mcount_loc section at build time.
0096
0097 config TRACER_MAX_TRACE
0098 bool
0099
0100 config TRACE_CLOCK
0101 bool
0102
0103 config RING_BUFFER
0104 bool
0105 select TRACE_CLOCK
0106 select IRQ_WORK
0107
0108 config EVENT_TRACING
0109 select CONTEXT_SWITCH_TRACER
0110 select GLOB
0111 bool
0112
0113 config CONTEXT_SWITCH_TRACER
0114 bool
0115
0116 config RING_BUFFER_ALLOW_SWAP
0117 bool
0118 help
0119 Allow the use of ring_buffer_swap_cpu.
0120 Adds a very slight overhead to tracing when enabled.
0121
0122 config PREEMPTIRQ_TRACEPOINTS
0123 bool
0124 depends on TRACE_PREEMPT_TOGGLE || TRACE_IRQFLAGS
0125 select TRACING
0126 default y
0127 help
0128 Create preempt/irq toggle tracepoints if needed, so that other parts
0129 of the kernel can use them to generate or add hooks to them.
0130
0131 # All tracer options should select GENERIC_TRACER. For those options that are
0132 # enabled by all tracers (context switch and event tracer) they select TRACING.
0133 # This allows those options to appear when no other tracer is selected. But the
0134 # options do not appear when something else selects it. We need the two options
0135 # GENERIC_TRACER and TRACING to avoid circular dependencies to accomplish the
0136 # hiding of the automatic options.
0137
0138 config TRACING
0139 bool
0140 select RING_BUFFER
0141 select STACKTRACE if STACKTRACE_SUPPORT
0142 select TRACEPOINTS
0143 select NOP_TRACER
0144 select BINARY_PRINTF
0145 select EVENT_TRACING
0146 select TRACE_CLOCK
0147 select TASKS_RCU if PREEMPTION
0148
0149 config GENERIC_TRACER
0150 bool
0151 select TRACING
0152
0153 #
0154 # Minimum requirements an architecture has to meet for us to
0155 # be able to offer generic tracing facilities:
0156 #
0157 config TRACING_SUPPORT
0158 bool
0159 depends on TRACE_IRQFLAGS_SUPPORT
0160 depends on STACKTRACE_SUPPORT
0161 default y
0162
0163 menuconfig FTRACE
0164 bool "Tracers"
0165 depends on TRACING_SUPPORT
0166 default y if DEBUG_KERNEL
0167 help
0168 Enable the kernel tracing infrastructure.
0169
0170 if FTRACE
0171
0172 config BOOTTIME_TRACING
0173 bool "Boot-time Tracing support"
0174 depends on TRACING
0175 select BOOT_CONFIG
0176 help
0177 Enable developer to setup ftrace subsystem via supplemental
0178 kernel cmdline at boot time for debugging (tracing) driver
0179 initialization and boot process.
0180
0181 config FUNCTION_TRACER
0182 bool "Kernel Function Tracer"
0183 depends on HAVE_FUNCTION_TRACER
0184 select KALLSYMS
0185 select GENERIC_TRACER
0186 select CONTEXT_SWITCH_TRACER
0187 select GLOB
0188 select TASKS_RCU if PREEMPTION
0189 select TASKS_RUDE_RCU
0190 help
0191 Enable the kernel to trace every kernel function. This is done
0192 by using a compiler feature to insert a small, 5-byte No-Operation
0193 instruction at the beginning of every kernel function, which NOP
0194 sequence is then dynamically patched into a tracer call when
0195 tracing is enabled by the administrator. If it's runtime disabled
0196 (the bootup default), then the overhead of the instructions is very
0197 small and not measurable even in micro-benchmarks (at least on
0198 x86, but may have impact on other architectures).
0199
0200 config FUNCTION_GRAPH_TRACER
0201 bool "Kernel Function Graph Tracer"
0202 depends on HAVE_FUNCTION_GRAPH_TRACER
0203 depends on FUNCTION_TRACER
0204 depends on !X86_32 || !CC_OPTIMIZE_FOR_SIZE
0205 default y
0206 help
0207 Enable the kernel to trace a function at both its return
0208 and its entry.
0209 Its first purpose is to trace the duration of functions and
0210 draw a call graph for each thread with some information like
0211 the return value. This is done by setting the current return
0212 address on the current task structure into a stack of calls.
0213
0214 config DYNAMIC_FTRACE
0215 bool "enable/disable function tracing dynamically"
0216 depends on FUNCTION_TRACER
0217 depends on HAVE_DYNAMIC_FTRACE
0218 default y
0219 help
0220 This option will modify all the calls to function tracing
0221 dynamically (will patch them out of the binary image and
0222 replace them with a No-Op instruction) on boot up. During
0223 compile time, a table is made of all the locations that ftrace
0224 can function trace, and this table is linked into the kernel
0225 image. When this is enabled, functions can be individually
0226 enabled, and the functions not enabled will not affect
0227 performance of the system.
0228
0229 See the files in /sys/kernel/debug/tracing:
0230 available_filter_functions
0231 set_ftrace_filter
0232 set_ftrace_notrace
0233
0234 This way a CONFIG_FUNCTION_TRACER kernel is slightly larger, but
0235 otherwise has native performance as long as no tracing is active.
0236
0237 config DYNAMIC_FTRACE_WITH_REGS
0238 def_bool y
0239 depends on DYNAMIC_FTRACE
0240 depends on HAVE_DYNAMIC_FTRACE_WITH_REGS
0241
0242 config DYNAMIC_FTRACE_WITH_DIRECT_CALLS
0243 def_bool y
0244 depends on DYNAMIC_FTRACE_WITH_REGS
0245 depends on HAVE_DYNAMIC_FTRACE_WITH_DIRECT_CALLS
0246
0247 config DYNAMIC_FTRACE_WITH_ARGS
0248 def_bool y
0249 depends on DYNAMIC_FTRACE
0250 depends on HAVE_DYNAMIC_FTRACE_WITH_ARGS
0251
0252 config FPROBE
0253 bool "Kernel Function Probe (fprobe)"
0254 depends on FUNCTION_TRACER
0255 depends on DYNAMIC_FTRACE_WITH_REGS
0256 depends on HAVE_RETHOOK
0257 select RETHOOK
0258 default n
0259 help
0260 This option enables kernel function probe (fprobe) based on ftrace.
0261 The fprobe is similar to kprobes, but probes only for kernel function
0262 entries and exits. This also can probe multiple functions by one
0263 fprobe.
0264
0265 If unsure, say N.
0266
0267 config FUNCTION_PROFILER
0268 bool "Kernel function profiler"
0269 depends on FUNCTION_TRACER
0270 default n
0271 help
0272 This option enables the kernel function profiler. A file is created
0273 in debugfs called function_profile_enabled which defaults to zero.
0274 When a 1 is echoed into this file profiling begins, and when a
0275 zero is entered, profiling stops. A "functions" file is created in
0276 the trace_stat directory; this file shows the list of functions that
0277 have been hit and their counters.
0278
0279 If in doubt, say N.
0280
0281 config STACK_TRACER
0282 bool "Trace max stack"
0283 depends on HAVE_FUNCTION_TRACER
0284 select FUNCTION_TRACER
0285 select STACKTRACE
0286 select KALLSYMS
0287 help
0288 This special tracer records the maximum stack footprint of the
0289 kernel and displays it in /sys/kernel/debug/tracing/stack_trace.
0290
0291 This tracer works by hooking into every function call that the
0292 kernel executes, and keeping a maximum stack depth value and
0293 stack-trace saved. If this is configured with DYNAMIC_FTRACE
0294 then it will not have any overhead while the stack tracer
0295 is disabled.
0296
0297 To enable the stack tracer on bootup, pass in 'stacktrace'
0298 on the kernel command line.
0299
0300 The stack tracer can also be enabled or disabled via the
0301 sysctl kernel.stack_tracer_enabled
0302
0303 Say N if unsure.
0304
0305 config TRACE_PREEMPT_TOGGLE
0306 bool
0307 help
0308 Enables hooks which will be called when preemption is first disabled,
0309 and last enabled.
0310
0311 config IRQSOFF_TRACER
0312 bool "Interrupts-off Latency Tracer"
0313 default n
0314 depends on TRACE_IRQFLAGS_SUPPORT
0315 select TRACE_IRQFLAGS
0316 select GENERIC_TRACER
0317 select TRACER_MAX_TRACE
0318 select RING_BUFFER_ALLOW_SWAP
0319 select TRACER_SNAPSHOT
0320 select TRACER_SNAPSHOT_PER_CPU_SWAP
0321 help
0322 This option measures the time spent in irqs-off critical
0323 sections, with microsecond accuracy.
0324
0325 The default measurement method is a maximum search, which is
0326 disabled by default and can be runtime (re-)started
0327 via:
0328
0329 echo 0 > /sys/kernel/debug/tracing/tracing_max_latency
0330
0331 (Note that kernel size and overhead increase with this option
0332 enabled. This option and the preempt-off timing option can be
0333 used together or separately.)
0334
0335 config PREEMPT_TRACER
0336 bool "Preemption-off Latency Tracer"
0337 default n
0338 depends on PREEMPTION
0339 select GENERIC_TRACER
0340 select TRACER_MAX_TRACE
0341 select RING_BUFFER_ALLOW_SWAP
0342 select TRACER_SNAPSHOT
0343 select TRACER_SNAPSHOT_PER_CPU_SWAP
0344 select TRACE_PREEMPT_TOGGLE
0345 help
0346 This option measures the time spent in preemption-off critical
0347 sections, with microsecond accuracy.
0348
0349 The default measurement method is a maximum search, which is
0350 disabled by default and can be runtime (re-)started
0351 via:
0352
0353 echo 0 > /sys/kernel/debug/tracing/tracing_max_latency
0354
0355 (Note that kernel size and overhead increase with this option
0356 enabled. This option and the irqs-off timing option can be
0357 used together or separately.)
0358
0359 config SCHED_TRACER
0360 bool "Scheduling Latency Tracer"
0361 select GENERIC_TRACER
0362 select CONTEXT_SWITCH_TRACER
0363 select TRACER_MAX_TRACE
0364 select TRACER_SNAPSHOT
0365 help
0366 This tracer tracks the latency of the highest priority task
0367 to be scheduled in, starting from the point it has woken up.
0368
0369 config HWLAT_TRACER
0370 bool "Tracer to detect hardware latencies (like SMIs)"
0371 select GENERIC_TRACER
0372 help
0373 This tracer, when enabled will create one or more kernel threads,
0374 depending on what the cpumask file is set to, which each thread
0375 spinning in a loop looking for interruptions caused by
0376 something other than the kernel. For example, if a
0377 System Management Interrupt (SMI) takes a noticeable amount of
0378 time, this tracer will detect it. This is useful for testing
0379 if a system is reliable for Real Time tasks.
0380
0381 Some files are created in the tracing directory when this
0382 is enabled:
0383
0384 hwlat_detector/width - time in usecs for how long to spin for
0385 hwlat_detector/window - time in usecs between the start of each
0386 iteration
0387
0388 A kernel thread is created that will spin with interrupts disabled
0389 for "width" microseconds in every "window" cycle. It will not spin
0390 for "window - width" microseconds, where the system can
0391 continue to operate.
0392
0393 The output will appear in the trace and trace_pipe files.
0394
0395 When the tracer is not running, it has no affect on the system,
0396 but when it is running, it can cause the system to be
0397 periodically non responsive. Do not run this tracer on a
0398 production system.
0399
0400 To enable this tracer, echo in "hwlat" into the current_tracer
0401 file. Every time a latency is greater than tracing_thresh, it will
0402 be recorded into the ring buffer.
0403
0404 config OSNOISE_TRACER
0405 bool "OS Noise tracer"
0406 select GENERIC_TRACER
0407 help
0408 In the context of high-performance computing (HPC), the Operating
0409 System Noise (osnoise) refers to the interference experienced by an
0410 application due to activities inside the operating system. In the
0411 context of Linux, NMIs, IRQs, SoftIRQs, and any other system thread
0412 can cause noise to the system. Moreover, hardware-related jobs can
0413 also cause noise, for example, via SMIs.
0414
0415 The osnoise tracer leverages the hwlat_detector by running a similar
0416 loop with preemption, SoftIRQs and IRQs enabled, thus allowing all
0417 the sources of osnoise during its execution. The osnoise tracer takes
0418 note of the entry and exit point of any source of interferences,
0419 increasing a per-cpu interference counter. It saves an interference
0420 counter for each source of interference. The interference counter for
0421 NMI, IRQs, SoftIRQs, and threads is increased anytime the tool
0422 observes these interferences' entry events. When a noise happens
0423 without any interference from the operating system level, the
0424 hardware noise counter increases, pointing to a hardware-related
0425 noise. In this way, osnoise can account for any source of
0426 interference. At the end of the period, the osnoise tracer prints
0427 the sum of all noise, the max single noise, the percentage of CPU
0428 available for the thread, and the counters for the noise sources.
0429
0430 In addition to the tracer, a set of tracepoints were added to
0431 facilitate the identification of the osnoise source.
0432
0433 The output will appear in the trace and trace_pipe files.
0434
0435 To enable this tracer, echo in "osnoise" into the current_tracer
0436 file.
0437
0438 config TIMERLAT_TRACER
0439 bool "Timerlat tracer"
0440 select OSNOISE_TRACER
0441 select GENERIC_TRACER
0442 help
0443 The timerlat tracer aims to help the preemptive kernel developers
0444 to find sources of wakeup latencies of real-time threads.
0445
0446 The tracer creates a per-cpu kernel thread with real-time priority.
0447 The tracer thread sets a periodic timer to wakeup itself, and goes
0448 to sleep waiting for the timer to fire. At the wakeup, the thread
0449 then computes a wakeup latency value as the difference between
0450 the current time and the absolute time that the timer was set
0451 to expire.
0452
0453 The tracer prints two lines at every activation. The first is the
0454 timer latency observed at the hardirq context before the
0455 activation of the thread. The second is the timer latency observed
0456 by the thread, which is the same level that cyclictest reports. The
0457 ACTIVATION ID field serves to relate the irq execution to its
0458 respective thread execution.
0459
0460 The tracer is build on top of osnoise tracer, and the osnoise:
0461 events can be used to trace the source of interference from NMI,
0462 IRQs and other threads. It also enables the capture of the
0463 stacktrace at the IRQ context, which helps to identify the code
0464 path that can cause thread delay.
0465
0466 config MMIOTRACE
0467 bool "Memory mapped IO tracing"
0468 depends on HAVE_MMIOTRACE_SUPPORT && PCI
0469 select GENERIC_TRACER
0470 help
0471 Mmiotrace traces Memory Mapped I/O access and is meant for
0472 debugging and reverse engineering. It is called from the ioremap
0473 implementation and works via page faults. Tracing is disabled by
0474 default and can be enabled at run-time.
0475
0476 See Documentation/trace/mmiotrace.rst.
0477 If you are not helping to develop drivers, say N.
0478
0479 config ENABLE_DEFAULT_TRACERS
0480 bool "Trace process context switches and events"
0481 depends on !GENERIC_TRACER
0482 select TRACING
0483 help
0484 This tracer hooks to various trace points in the kernel,
0485 allowing the user to pick and choose which trace point they
0486 want to trace. It also includes the sched_switch tracer plugin.
0487
0488 config FTRACE_SYSCALLS
0489 bool "Trace syscalls"
0490 depends on HAVE_SYSCALL_TRACEPOINTS
0491 select GENERIC_TRACER
0492 select KALLSYMS
0493 help
0494 Basic tracer to catch the syscall entry and exit events.
0495
0496 config TRACER_SNAPSHOT
0497 bool "Create a snapshot trace buffer"
0498 select TRACER_MAX_TRACE
0499 help
0500 Allow tracing users to take snapshot of the current buffer using the
0501 ftrace interface, e.g.:
0502
0503 echo 1 > /sys/kernel/debug/tracing/snapshot
0504 cat snapshot
0505
0506 config TRACER_SNAPSHOT_PER_CPU_SWAP
0507 bool "Allow snapshot to swap per CPU"
0508 depends on TRACER_SNAPSHOT
0509 select RING_BUFFER_ALLOW_SWAP
0510 help
0511 Allow doing a snapshot of a single CPU buffer instead of a
0512 full swap (all buffers). If this is set, then the following is
0513 allowed:
0514
0515 echo 1 > /sys/kernel/debug/tracing/per_cpu/cpu2/snapshot
0516
0517 After which, only the tracing buffer for CPU 2 was swapped with
0518 the main tracing buffer, and the other CPU buffers remain the same.
0519
0520 When this is enabled, this adds a little more overhead to the
0521 trace recording, as it needs to add some checks to synchronize
0522 recording with swaps. But this does not affect the performance
0523 of the overall system. This is enabled by default when the preempt
0524 or irq latency tracers are enabled, as those need to swap as well
0525 and already adds the overhead (plus a lot more).
0526
0527 config TRACE_BRANCH_PROFILING
0528 bool
0529 select GENERIC_TRACER
0530
0531 choice
0532 prompt "Branch Profiling"
0533 default BRANCH_PROFILE_NONE
0534 help
0535 The branch profiling is a software profiler. It will add hooks
0536 into the C conditionals to test which path a branch takes.
0537
0538 The likely/unlikely profiler only looks at the conditions that
0539 are annotated with a likely or unlikely macro.
0540
0541 The "all branch" profiler will profile every if-statement in the
0542 kernel. This profiler will also enable the likely/unlikely
0543 profiler.
0544
0545 Either of the above profilers adds a bit of overhead to the system.
0546 If unsure, choose "No branch profiling".
0547
0548 config BRANCH_PROFILE_NONE
0549 bool "No branch profiling"
0550 help
0551 No branch profiling. Branch profiling adds a bit of overhead.
0552 Only enable it if you want to analyse the branching behavior.
0553 Otherwise keep it disabled.
0554
0555 config PROFILE_ANNOTATED_BRANCHES
0556 bool "Trace likely/unlikely profiler"
0557 select TRACE_BRANCH_PROFILING
0558 help
0559 This tracer profiles all likely and unlikely macros
0560 in the kernel. It will display the results in:
0561
0562 /sys/kernel/debug/tracing/trace_stat/branch_annotated
0563
0564 Note: this will add a significant overhead; only turn this
0565 on if you need to profile the system's use of these macros.
0566
0567 config PROFILE_ALL_BRANCHES
0568 bool "Profile all if conditionals" if !FORTIFY_SOURCE
0569 select TRACE_BRANCH_PROFILING
0570 help
0571 This tracer profiles all branch conditions. Every if ()
0572 taken in the kernel is recorded whether it hit or miss.
0573 The results will be displayed in:
0574
0575 /sys/kernel/debug/tracing/trace_stat/branch_all
0576
0577 This option also enables the likely/unlikely profiler.
0578
0579 This configuration, when enabled, will impose a great overhead
0580 on the system. This should only be enabled when the system
0581 is to be analyzed in much detail.
0582 endchoice
0583
0584 config TRACING_BRANCHES
0585 bool
0586 help
0587 Selected by tracers that will trace the likely and unlikely
0588 conditions. This prevents the tracers themselves from being
0589 profiled. Profiling the tracing infrastructure can only happen
0590 when the likelys and unlikelys are not being traced.
0591
0592 config BRANCH_TRACER
0593 bool "Trace likely/unlikely instances"
0594 depends on TRACE_BRANCH_PROFILING
0595 select TRACING_BRANCHES
0596 help
0597 This traces the events of likely and unlikely condition
0598 calls in the kernel. The difference between this and the
0599 "Trace likely/unlikely profiler" is that this is not a
0600 histogram of the callers, but actually places the calling
0601 events into a running trace buffer to see when and where the
0602 events happened, as well as their results.
0603
0604 Say N if unsure.
0605
0606 config BLK_DEV_IO_TRACE
0607 bool "Support for tracing block IO actions"
0608 depends on SYSFS
0609 depends on BLOCK
0610 select RELAY
0611 select DEBUG_FS
0612 select TRACEPOINTS
0613 select GENERIC_TRACER
0614 select STACKTRACE
0615 help
0616 Say Y here if you want to be able to trace the block layer actions
0617 on a given queue. Tracing allows you to see any traffic happening
0618 on a block device queue. For more information (and the userspace
0619 support tools needed), fetch the blktrace tools from:
0620
0621 git://git.kernel.dk/blktrace.git
0622
0623 Tracing also is possible using the ftrace interface, e.g.:
0624
0625 echo 1 > /sys/block/sda/sda1/trace/enable
0626 echo blk > /sys/kernel/debug/tracing/current_tracer
0627 cat /sys/kernel/debug/tracing/trace_pipe
0628
0629 If unsure, say N.
0630
0631 config KPROBE_EVENTS
0632 depends on KPROBES
0633 depends on HAVE_REGS_AND_STACK_ACCESS_API
0634 bool "Enable kprobes-based dynamic events"
0635 select TRACING
0636 select PROBE_EVENTS
0637 select DYNAMIC_EVENTS
0638 default y
0639 help
0640 This allows the user to add tracing events (similar to tracepoints)
0641 on the fly via the ftrace interface. See
0642 Documentation/trace/kprobetrace.rst for more details.
0643
0644 Those events can be inserted wherever kprobes can probe, and record
0645 various register and memory values.
0646
0647 This option is also required by perf-probe subcommand of perf tools.
0648 If you want to use perf tools, this option is strongly recommended.
0649
0650 config KPROBE_EVENTS_ON_NOTRACE
0651 bool "Do NOT protect notrace function from kprobe events"
0652 depends on KPROBE_EVENTS
0653 depends on DYNAMIC_FTRACE
0654 default n
0655 help
0656 This is only for the developers who want to debug ftrace itself
0657 using kprobe events.
0658
0659 If kprobes can use ftrace instead of breakpoint, ftrace related
0660 functions are protected from kprobe-events to prevent an infinite
0661 recursion or any unexpected execution path which leads to a kernel
0662 crash.
0663
0664 This option disables such protection and allows you to put kprobe
0665 events on ftrace functions for debugging ftrace by itself.
0666 Note that this might let you shoot yourself in the foot.
0667
0668 If unsure, say N.
0669
0670 config UPROBE_EVENTS
0671 bool "Enable uprobes-based dynamic events"
0672 depends on ARCH_SUPPORTS_UPROBES
0673 depends on MMU
0674 depends on PERF_EVENTS
0675 select UPROBES
0676 select PROBE_EVENTS
0677 select DYNAMIC_EVENTS
0678 select TRACING
0679 default y
0680 help
0681 This allows the user to add tracing events on top of userspace
0682 dynamic events (similar to tracepoints) on the fly via the trace
0683 events interface. Those events can be inserted wherever uprobes
0684 can probe, and record various registers.
0685 This option is required if you plan to use perf-probe subcommand
0686 of perf tools on user space applications.
0687
0688 config BPF_EVENTS
0689 depends on BPF_SYSCALL
0690 depends on (KPROBE_EVENTS || UPROBE_EVENTS) && PERF_EVENTS
0691 bool
0692 default y
0693 help
0694 This allows the user to attach BPF programs to kprobe, uprobe, and
0695 tracepoint events.
0696
0697 config DYNAMIC_EVENTS
0698 def_bool n
0699
0700 config PROBE_EVENTS
0701 def_bool n
0702
0703 config BPF_KPROBE_OVERRIDE
0704 bool "Enable BPF programs to override a kprobed function"
0705 depends on BPF_EVENTS
0706 depends on FUNCTION_ERROR_INJECTION
0707 default n
0708 help
0709 Allows BPF to override the execution of a probed function and
0710 set a different return value. This is used for error injection.
0711
0712 config FTRACE_MCOUNT_RECORD
0713 def_bool y
0714 depends on DYNAMIC_FTRACE
0715 depends on HAVE_FTRACE_MCOUNT_RECORD
0716
0717 config FTRACE_MCOUNT_USE_PATCHABLE_FUNCTION_ENTRY
0718 bool
0719 depends on FTRACE_MCOUNT_RECORD
0720
0721 config FTRACE_MCOUNT_USE_CC
0722 def_bool y
0723 depends on $(cc-option,-mrecord-mcount)
0724 depends on !FTRACE_MCOUNT_USE_PATCHABLE_FUNCTION_ENTRY
0725 depends on FTRACE_MCOUNT_RECORD
0726
0727 config FTRACE_MCOUNT_USE_OBJTOOL
0728 def_bool y
0729 depends on HAVE_OBJTOOL_MCOUNT
0730 depends on !FTRACE_MCOUNT_USE_PATCHABLE_FUNCTION_ENTRY
0731 depends on !FTRACE_MCOUNT_USE_CC
0732 depends on FTRACE_MCOUNT_RECORD
0733 select OBJTOOL
0734
0735 config FTRACE_MCOUNT_USE_RECORDMCOUNT
0736 def_bool y
0737 depends on !FTRACE_MCOUNT_USE_PATCHABLE_FUNCTION_ENTRY
0738 depends on !FTRACE_MCOUNT_USE_CC
0739 depends on !FTRACE_MCOUNT_USE_OBJTOOL
0740 depends on FTRACE_MCOUNT_RECORD
0741
0742 config TRACING_MAP
0743 bool
0744 depends on ARCH_HAVE_NMI_SAFE_CMPXCHG
0745 help
0746 tracing_map is a special-purpose lock-free map for tracing,
0747 separated out as a stand-alone facility in order to allow it
0748 to be shared between multiple tracers. It isn't meant to be
0749 generally used outside of that context, and is normally
0750 selected by tracers that use it.
0751
0752 config SYNTH_EVENTS
0753 bool "Synthetic trace events"
0754 select TRACING
0755 select DYNAMIC_EVENTS
0756 default n
0757 help
0758 Synthetic events are user-defined trace events that can be
0759 used to combine data from other trace events or in fact any
0760 data source. Synthetic events can be generated indirectly
0761 via the trace() action of histogram triggers or directly
0762 by way of an in-kernel API.
0763
0764 See Documentation/trace/events.rst or
0765 Documentation/trace/histogram.rst for details and examples.
0766
0767 If in doubt, say N.
0768
0769 config USER_EVENTS
0770 bool "User trace events"
0771 select TRACING
0772 select DYNAMIC_EVENTS
0773 depends on BROKEN || COMPILE_TEST # API needs to be straighten out
0774 help
0775 User trace events are user-defined trace events that
0776 can be used like an existing kernel trace event. User trace
0777 events are generated by writing to a tracefs file. User
0778 processes can determine if their tracing events should be
0779 generated by memory mapping a tracefs file and checking for
0780 an associated byte being non-zero.
0781
0782 If in doubt, say N.
0783
0784 config HIST_TRIGGERS
0785 bool "Histogram triggers"
0786 depends on ARCH_HAVE_NMI_SAFE_CMPXCHG
0787 select TRACING_MAP
0788 select TRACING
0789 select DYNAMIC_EVENTS
0790 select SYNTH_EVENTS
0791 default n
0792 help
0793 Hist triggers allow one or more arbitrary trace event fields
0794 to be aggregated into hash tables and dumped to stdout by
0795 reading a debugfs/tracefs file. They're useful for
0796 gathering quick and dirty (though precise) summaries of
0797 event activity as an initial guide for further investigation
0798 using more advanced tools.
0799
0800 Inter-event tracing of quantities such as latencies is also
0801 supported using hist triggers under this option.
0802
0803 See Documentation/trace/histogram.rst.
0804 If in doubt, say N.
0805
0806 config TRACE_EVENT_INJECT
0807 bool "Trace event injection"
0808 depends on TRACING
0809 help
0810 Allow user-space to inject a specific trace event into the ring
0811 buffer. This is mainly used for testing purpose.
0812
0813 If unsure, say N.
0814
0815 config TRACEPOINT_BENCHMARK
0816 bool "Add tracepoint that benchmarks tracepoints"
0817 help
0818 This option creates the tracepoint "benchmark:benchmark_event".
0819 When the tracepoint is enabled, it kicks off a kernel thread that
0820 goes into an infinite loop (calling cond_resched() to let other tasks
0821 run), and calls the tracepoint. Each iteration will record the time
0822 it took to write to the tracepoint and the next iteration that
0823 data will be passed to the tracepoint itself. That is, the tracepoint
0824 will report the time it took to do the previous tracepoint.
0825 The string written to the tracepoint is a static string of 128 bytes
0826 to keep the time the same. The initial string is simply a write of
0827 "START". The second string records the cold cache time of the first
0828 write which is not added to the rest of the calculations.
0829
0830 As it is a tight loop, it benchmarks as hot cache. That's fine because
0831 we care most about hot paths that are probably in cache already.
0832
0833 An example of the output:
0834
0835 START
0836 first=3672 [COLD CACHED]
0837 last=632 first=3672 max=632 min=632 avg=316 std=446 std^2=199712
0838 last=278 first=3672 max=632 min=278 avg=303 std=316 std^2=100337
0839 last=277 first=3672 max=632 min=277 avg=296 std=258 std^2=67064
0840 last=273 first=3672 max=632 min=273 avg=292 std=224 std^2=50411
0841 last=273 first=3672 max=632 min=273 avg=288 std=200 std^2=40389
0842 last=281 first=3672 max=632 min=273 avg=287 std=183 std^2=33666
0843
0844
0845 config RING_BUFFER_BENCHMARK
0846 tristate "Ring buffer benchmark stress tester"
0847 depends on RING_BUFFER
0848 help
0849 This option creates a test to stress the ring buffer and benchmark it.
0850 It creates its own ring buffer such that it will not interfere with
0851 any other users of the ring buffer (such as ftrace). It then creates
0852 a producer and consumer that will run for 10 seconds and sleep for
0853 10 seconds. Each interval it will print out the number of events
0854 it recorded and give a rough estimate of how long each iteration took.
0855
0856 It does not disable interrupts or raise its priority, so it may be
0857 affected by processes that are running.
0858
0859 If unsure, say N.
0860
0861 config TRACE_EVAL_MAP_FILE
0862 bool "Show eval mappings for trace events"
0863 depends on TRACING
0864 help
0865 The "print fmt" of the trace events will show the enum/sizeof names
0866 instead of their values. This can cause problems for user space tools
0867 that use this string to parse the raw data as user space does not know
0868 how to convert the string to its value.
0869
0870 To fix this, there's a special macro in the kernel that can be used
0871 to convert an enum/sizeof into its value. If this macro is used, then
0872 the print fmt strings will be converted to their values.
0873
0874 If something does not get converted properly, this option can be
0875 used to show what enums/sizeof the kernel tried to convert.
0876
0877 This option is for debugging the conversions. A file is created
0878 in the tracing directory called "eval_map" that will show the
0879 names matched with their values and what trace event system they
0880 belong too.
0881
0882 Normally, the mapping of the strings to values will be freed after
0883 boot up or module load. With this option, they will not be freed, as
0884 they are needed for the "eval_map" file. Enabling this option will
0885 increase the memory footprint of the running kernel.
0886
0887 If unsure, say N.
0888
0889 config FTRACE_RECORD_RECURSION
0890 bool "Record functions that recurse in function tracing"
0891 depends on FUNCTION_TRACER
0892 help
0893 All callbacks that attach to the function tracing have some sort
0894 of protection against recursion. Even though the protection exists,
0895 it adds overhead. This option will create a file in the tracefs
0896 file system called "recursed_functions" that will list the functions
0897 that triggered a recursion.
0898
0899 This will add more overhead to cases that have recursion.
0900
0901 If unsure, say N
0902
0903 config FTRACE_RECORD_RECURSION_SIZE
0904 int "Max number of recursed functions to record"
0905 default 128
0906 depends on FTRACE_RECORD_RECURSION
0907 help
0908 This defines the limit of number of functions that can be
0909 listed in the "recursed_functions" file, that lists all
0910 the functions that caused a recursion to happen.
0911 This file can be reset, but the limit can not change in
0912 size at runtime.
0913
0914 config RING_BUFFER_RECORD_RECURSION
0915 bool "Record functions that recurse in the ring buffer"
0916 depends on FTRACE_RECORD_RECURSION
0917 # default y, because it is coupled with FTRACE_RECORD_RECURSION
0918 default y
0919 help
0920 The ring buffer has its own internal recursion. Although when
0921 recursion happens it wont cause harm because of the protection,
0922 but it does cause an unwanted overhead. Enabling this option will
0923 place where recursion was detected into the ftrace "recursed_functions"
0924 file.
0925
0926 This will add more overhead to cases that have recursion.
0927
0928 config GCOV_PROFILE_FTRACE
0929 bool "Enable GCOV profiling on ftrace subsystem"
0930 depends on GCOV_KERNEL
0931 help
0932 Enable GCOV profiling on ftrace subsystem for checking
0933 which functions/lines are tested.
0934
0935 If unsure, say N.
0936
0937 Note that on a kernel compiled with this config, ftrace will
0938 run significantly slower.
0939
0940 config FTRACE_SELFTEST
0941 bool
0942
0943 config FTRACE_STARTUP_TEST
0944 bool "Perform a startup test on ftrace"
0945 depends on GENERIC_TRACER
0946 select FTRACE_SELFTEST
0947 help
0948 This option performs a series of startup tests on ftrace. On bootup
0949 a series of tests are made to verify that the tracer is
0950 functioning properly. It will do tests on all the configured
0951 tracers of ftrace.
0952
0953 config EVENT_TRACE_STARTUP_TEST
0954 bool "Run selftest on trace events"
0955 depends on FTRACE_STARTUP_TEST
0956 default y
0957 help
0958 This option performs a test on all trace events in the system.
0959 It basically just enables each event and runs some code that
0960 will trigger events (not necessarily the event it enables)
0961 This may take some time run as there are a lot of events.
0962
0963 config EVENT_TRACE_TEST_SYSCALLS
0964 bool "Run selftest on syscall events"
0965 depends on EVENT_TRACE_STARTUP_TEST
0966 help
0967 This option will also enable testing every syscall event.
0968 It only enables the event and disables it and runs various loads
0969 with the event enabled. This adds a bit more time for kernel boot
0970 up since it runs this on every system call defined.
0971
0972 TBD - enable a way to actually call the syscalls as we test their
0973 events
0974
0975 config FTRACE_SORT_STARTUP_TEST
0976 bool "Verify compile time sorting of ftrace functions"
0977 depends on DYNAMIC_FTRACE
0978 depends on BUILDTIME_MCOUNT_SORT
0979 help
0980 Sorting of the mcount_loc sections that is used to find the
0981 where the ftrace knows where to patch functions for tracing
0982 and other callbacks is done at compile time. But if the sort
0983 is not done correctly, it will cause non-deterministic failures.
0984 When this is set, the sorted sections will be verified that they
0985 are in deed sorted and will warn if they are not.
0986
0987 If unsure, say N
0988
0989 config RING_BUFFER_STARTUP_TEST
0990 bool "Ring buffer startup self test"
0991 depends on RING_BUFFER
0992 help
0993 Run a simple self test on the ring buffer on boot up. Late in the
0994 kernel boot sequence, the test will start that kicks off
0995 a thread per cpu. Each thread will write various size events
0996 into the ring buffer. Another thread is created to send IPIs
0997 to each of the threads, where the IPI handler will also write
0998 to the ring buffer, to test/stress the nesting ability.
0999 If any anomalies are discovered, a warning will be displayed
1000 and all ring buffers will be disabled.
1001
1002 The test runs for 10 seconds. This will slow your boot time
1003 by at least 10 more seconds.
1004
1005 At the end of the test, statics and more checks are done.
1006 It will output the stats of each per cpu buffer. What
1007 was written, the sizes, what was read, what was lost, and
1008 other similar details.
1009
1010 If unsure, say N
1011
1012 config RING_BUFFER_VALIDATE_TIME_DELTAS
1013 bool "Verify ring buffer time stamp deltas"
1014 depends on RING_BUFFER
1015 help
1016 This will audit the time stamps on the ring buffer sub
1017 buffer to make sure that all the time deltas for the
1018 events on a sub buffer matches the current time stamp.
1019 This audit is performed for every event that is not
1020 interrupted, or interrupting another event. A check
1021 is also made when traversing sub buffers to make sure
1022 that all the deltas on the previous sub buffer do not
1023 add up to be greater than the current time stamp.
1024
1025 NOTE: This adds significant overhead to recording of events,
1026 and should only be used to test the logic of the ring buffer.
1027 Do not use it on production systems.
1028
1029 Only say Y if you understand what this does, and you
1030 still want it enabled. Otherwise say N
1031
1032 config MMIOTRACE_TEST
1033 tristate "Test module for mmiotrace"
1034 depends on MMIOTRACE && m
1035 help
1036 This is a dumb module for testing mmiotrace. It is very dangerous
1037 as it will write garbage to IO memory starting at a given address.
1038 However, it should be safe to use on e.g. unused portion of VRAM.
1039
1040 Say N, unless you absolutely know what you are doing.
1041
1042 config PREEMPTIRQ_DELAY_TEST
1043 tristate "Test module to create a preempt / IRQ disable delay thread to test latency tracers"
1044 depends on m
1045 help
1046 Select this option to build a test module that can help test latency
1047 tracers by executing a preempt or irq disable section with a user
1048 configurable delay. The module busy waits for the duration of the
1049 critical section.
1050
1051 For example, the following invocation generates a burst of three
1052 irq-disabled critical sections for 500us:
1053 modprobe preemptirq_delay_test test_mode=irq delay=500 burst_size=3
1054
1055 What's more, if you want to attach the test on the cpu which the latency
1056 tracer is running on, specify cpu_affinity=cpu_num at the end of the
1057 command.
1058
1059 If unsure, say N
1060
1061 config SYNTH_EVENT_GEN_TEST
1062 tristate "Test module for in-kernel synthetic event generation"
1063 depends on SYNTH_EVENTS
1064 help
1065 This option creates a test module to check the base
1066 functionality of in-kernel synthetic event definition and
1067 generation.
1068
1069 To test, insert the module, and then check the trace buffer
1070 for the generated sample events.
1071
1072 If unsure, say N.
1073
1074 config KPROBE_EVENT_GEN_TEST
1075 tristate "Test module for in-kernel kprobe event generation"
1076 depends on KPROBE_EVENTS
1077 help
1078 This option creates a test module to check the base
1079 functionality of in-kernel kprobe event definition.
1080
1081 To test, insert the module, and then check the trace buffer
1082 for the generated kprobe events.
1083
1084 If unsure, say N.
1085
1086 config HIST_TRIGGERS_DEBUG
1087 bool "Hist trigger debug support"
1088 depends on HIST_TRIGGERS
1089 help
1090 Add "hist_debug" file for each event, which when read will
1091 dump out a bunch of internal details about the hist triggers
1092 defined on that event.
1093
1094 The hist_debug file serves a couple of purposes:
1095
1096 - Helps developers verify that nothing is broken.
1097
1098 - Provides educational information to support the details
1099 of the hist trigger internals as described by
1100 Documentation/trace/histogram-design.rst.
1101
1102 The hist_debug output only covers the data structures
1103 related to the histogram definitions themselves and doesn't
1104 display the internals of map buckets or variable values of
1105 running histograms.
1106
1107 If unsure, say N.
1108
1109 source "kernel/trace/rv/Kconfig"
1110
1111 endif # FTRACE
