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