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 7 config USER_STACKTRACE_SUPPORT 8 bool 9 10 config NOP_TRACER 11 bool 12 13 config HAVE_RETHOOK 14 bool 15 16 config 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 24 config HAVE_FUNCTION_TRACER 25 bool 26 help 27 See Documentation/trace/ftrace-design.rst 28 29 config HAVE_FUNCTION_GRAPH_TRACER 30 bool 31 help 32 See Documentation/trace/ftrace-design.rst 33 34 config HAVE_FUNCTION_GRAPH_RETVAL 35 bool 36 37 config HAVE_DYNAMIC_FTRACE 38 bool 39 help 40 See Documentation/trace/ftrace-design.rst 41 42 config HAVE_DYNAMIC_FTRACE_WITH_REGS 43 bool 44 45 config HAVE_DYNAMIC_FTRACE_WITH_DIRECT_CALLS 46 bool 47 48 config HAVE_DYNAMIC_FTRACE_WITH_CALL_OPS 49 bool 50 51 config 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 60 config 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 66 config HAVE_FTRACE_MCOUNT_RECORD 67 bool 68 help 69 See Documentation/trace/ftrace-design.rst 70 71 config HAVE_SYSCALL_TRACEPOINTS 72 bool 73 help 74 See Documentation/trace/ftrace-design.rst 75 76 config HAVE_FENTRY 77 bool 78 help 79 Arch supports the gcc options -pg with -mfentry 80 81 config HAVE_NOP_MCOUNT 82 bool 83 help 84 Arch supports the gcc options -pg with -mrecord-mcount and -nop-mcount 85 86 config HAVE_OBJTOOL_MCOUNT 87 bool 88 help 89 Arch supports objtool --mcount 90 91 config 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 98 config HAVE_C_RECORDMCOUNT 99 bool 100 help 101 C version of recordmcount available? 102 103 config HAVE_BUILDTIME_MCOUNT_SORT 104 bool 105 help 106 An architecture selects this if it sorts the mcount_loc section 107 at build time. 108 109 config 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. 115 116 config TRACER_MAX_TRACE 117 bool 118 119 config TRACE_CLOCK 120 bool 121 122 config RING_BUFFER 123 bool 124 select TRACE_CLOCK 125 select IRQ_WORK 126 127 config EVENT_TRACING 128 select CONTEXT_SWITCH_TRACER 129 select GLOB 130 bool 131 132 config CONTEXT_SWITCH_TRACER 133 bool 134 135 config 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. 140 141 config 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. 156 157 config 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 167 168 config 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 # 176 config TRACING_SUPPORT 177 bool 178 depends on TRACE_IRQFLAGS_SUPPORT 179 depends on STACKTRACE_SUPPORT 180 default y 181 182 menuconfig FTRACE 183 bool "Tracers" 184 depends on TRACING_SUPPORT 185 default y if DEBUG_KERNEL 186 help 187 Enable the kernel tracing infrastructure. 188 189 if FTRACE 190 191 config 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. 199 200 config 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). 218 219 config 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. 232 233 config 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 244 245 config 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. 267 268 config DYNAMIC_FTRACE_WITH_REGS 269 def_bool y 270 depends on DYNAMIC_FTRACE 271 depends on HAVE_DYNAMIC_FTRACE_WITH_REGS 272 273 config 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 277 278 config DYNAMIC_FTRACE_WITH_CALL_OPS 279 def_bool y 280 depends on HAVE_DYNAMIC_FTRACE_WITH_CALL_OPS 281 282 config DYNAMIC_FTRACE_WITH_ARGS 283 def_bool y 284 depends on DYNAMIC_FTRACE 285 depends on HAVE_DYNAMIC_FTRACE_WITH_ARGS 286 287 config 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. 301 302 config 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. 315 316 config 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. 339 340 config TRACE_PREEMPT_TOGGLE 341 bool 342 help 343 Enables hooks which will be called when preemption is first disabled, 344 and last enabled. 345 346 config 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.) 369 370 config 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.) 393 394 config 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. 403 404 config 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. 439 440 config 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. 474 475 config 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. 502 503 config 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. 515 516 config 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. 524 525 config 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. 532 533 config 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 542 543 config 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). 563 564 config TRACE_BRANCH_PROFILING 565 bool 566 select GENERIC_TRACER 567 568 choice 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". 584 585 config 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. 591 592 config 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. 603 604 config 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. 619 endchoice 620 621 config 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. 628 629 config 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. 642 643 config 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. 667 668 config 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. 681 682 config 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. 693 694 config 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. 712 713 config 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. 732 733 config 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. 750 751 config 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. 759 760 config DYNAMIC_EVENTS 761 def_bool n 762 763 config PROBE_EVENTS 764 def_bool n 765 766 config 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. 774 775 config FTRACE_MCOUNT_RECORD 776 def_bool y 777 depends on DYNAMIC_FTRACE 778 depends on HAVE_FTRACE_MCOUNT_RECORD 779 780 config FTRACE_MCOUNT_USE_PATCHABLE_FUNCTION_ENTRY 781 bool 782 depends on FTRACE_MCOUNT_RECORD 783 784 config 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 789 790 config 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 797 798 config 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 804 805 config 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. 814 815 config 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. 831 832 config 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. 846 847 config 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. 868 869 config 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. 877 878 config 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 906 907 908 config 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. 923 924 config 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. 951 952 config 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 965 966 config 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. 976 977 config FTRACE_VALIDATE_RCU_IS_WATCHING 978 bool "Validate RCU is on during ftrace execution" 979 depends on FUNCTION_TRACER 980 depends on ARCH_WANTS_NO_INSTR 981 help 982 All callbacks that attach to the function tracing have some sort of 983 protection against recursion. This option is only to verify that 984 ftrace (and other users of ftrace_test_recursion_trylock()) are not 985 called outside of RCU, as if they are, it can cause a race. But it 986 also has a noticeable overhead when enabled. 987 988 If unsure, say N 989 990 config RING_BUFFER_RECORD_RECURSION 991 bool "Record functions that recurse in the ring buffer" 992 depends on FTRACE_RECORD_RECURSION 993 # default y, because it is coupled with FTRACE_RECORD_RECURSION 994 default y 995 help 996 The ring buffer has its own internal recursion. Although when 997 recursion happens it won't cause harm because of the protection, 998 but it does cause unwanted overhead. Enabling this option will 999 place where recursion was detected into the ftrace "recursed_functions" 1000 file. 1001 1002 This will add more overhead to cases that have recursion. 1003 1004 config GCOV_PROFILE_FTRACE 1005 bool "Enable GCOV profiling on ftrace subsystem" 1006 depends on GCOV_KERNEL 1007 help 1008 Enable GCOV profiling on ftrace subsystem for checking 1009 which functions/lines are tested. 1010 1011 If unsure, say N. 1012 1013 Note that on a kernel compiled with this config, ftrace will 1014 run significantly slower. 1015 1016 config FTRACE_SELFTEST 1017 bool 1018 1019 config FTRACE_STARTUP_TEST 1020 bool "Perform a startup test on ftrace" 1021 depends on GENERIC_TRACER 1022 select FTRACE_SELFTEST 1023 help 1024 This option performs a series of startup tests on ftrace. On bootup 1025 a series of tests are made to verify that the tracer is 1026 functioning properly. It will do tests on all the configured 1027 tracers of ftrace. 1028 1029 config EVENT_TRACE_STARTUP_TEST 1030 bool "Run selftest on trace events" 1031 depends on FTRACE_STARTUP_TEST 1032 default y 1033 help 1034 This option performs a test on all trace events in the system. 1035 It basically just enables each event and runs some code that 1036 will trigger events (not necessarily the event it enables) 1037 This may take some time run as there are a lot of events. 1038 1039 config EVENT_TRACE_TEST_SYSCALLS 1040 bool "Run selftest on syscall events" 1041 depends on EVENT_TRACE_STARTUP_TEST 1042 help 1043 This option will also enable testing every syscall event. 1044 It only enables the event and disables it and runs various loads 1045 with the event enabled. This adds a bit more time for kernel boot 1046 up since it runs this on every system call defined. 1047 1048 TBD - enable a way to actually call the syscalls as we test their 1049 events 1050 1051 config FTRACE_SORT_STARTUP_TEST 1052 bool "Verify compile time sorting of ftrace functions" 1053 depends on DYNAMIC_FTRACE 1054 depends on BUILDTIME_MCOUNT_SORT 1055 help 1056 Sorting of the mcount_loc sections that is used to find the 1057 where the ftrace knows where to patch functions for tracing 1058 and other callbacks is done at compile time. But if the sort 1059 is not done correctly, it will cause non-deterministic failures. 1060 When this is set, the sorted sections will be verified that they 1061 are in deed sorted and will warn if they are not. 1062 1063 If unsure, say N 1064 1065 config RING_BUFFER_STARTUP_TEST 1066 bool "Ring buffer startup self test" 1067 depends on RING_BUFFER 1068 help 1069 Run a simple self test on the ring buffer on boot up. Late in the 1070 kernel boot sequence, the test will start that kicks off 1071 a thread per cpu. Each thread will write various size events 1072 into the ring buffer. Another thread is created to send IPIs 1073 to each of the threads, where the IPI handler will also write 1074 to the ring buffer, to test/stress the nesting ability. 1075 If any anomalies are discovered, a warning will be displayed 1076 and all ring buffers will be disabled. 1077 1078 The test runs for 10 seconds. This will slow your boot time 1079 by at least 10 more seconds. 1080 1081 At the end of the test, statistics and more checks are done. 1082 It will output the stats of each per cpu buffer: What 1083 was written, the sizes, what was read, what was lost, and 1084 other similar details. 1085 1086 If unsure, say N 1087 1088 config RING_BUFFER_VALIDATE_TIME_DELTAS 1089 bool "Verify ring buffer time stamp deltas" 1090 depends on RING_BUFFER 1091 help 1092 This will audit the time stamps on the ring buffer sub 1093 buffer to make sure that all the time deltas for the 1094 events on a sub buffer matches the current time stamp. 1095 This audit is performed for every event that is not 1096 interrupted, or interrupting another event. A check 1097 is also made when traversing sub buffers to make sure 1098 that all the deltas on the previous sub buffer do not 1099 add up to be greater than the current time stamp. 1100 1101 NOTE: This adds significant overhead to recording of events, 1102 and should only be used to test the logic of the ring buffer. 1103 Do not use it on production systems. 1104 1105 Only say Y if you understand what this does, and you 1106 still want it enabled. Otherwise say N 1107 1108 config MMIOTRACE_TEST 1109 tristate "Test module for mmiotrace" 1110 depends on MMIOTRACE && m 1111 help 1112 This is a dumb module for testing mmiotrace. It is very dangerous 1113 as it will write garbage to IO memory starting at a given address. 1114 However, it should be safe to use on e.g. unused portion of VRAM. 1115 1116 Say N, unless you absolutely know what you are doing. 1117 1118 config PREEMPTIRQ_DELAY_TEST 1119 tristate "Test module to create a preempt / IRQ disable delay thread to test latency tracers" 1120 depends on m 1121 help 1122 Select this option to build a test module that can help test latency 1123 tracers by executing a preempt or irq disable section with a user 1124 configurable delay. The module busy waits for the duration of the 1125 critical section. 1126 1127 For example, the following invocation generates a burst of three 1128 irq-disabled critical sections for 500us: 1129 modprobe preemptirq_delay_test test_mode=irq delay=500 burst_size=3 1130 1131 What's more, if you want to attach the test on the cpu which the latency 1132 tracer is running on, specify cpu_affinity=cpu_num at the end of the 1133 command. 1134 1135 If unsure, say N 1136 1137 config SYNTH_EVENT_GEN_TEST 1138 tristate "Test module for in-kernel synthetic event generation" 1139 depends on SYNTH_EVENTS && m 1140 help 1141 This option creates a test module to check the base 1142 functionality of in-kernel synthetic event definition and 1143 generation. 1144 1145 To test, insert the module, and then check the trace buffer 1146 for the generated sample events. 1147 1148 If unsure, say N. 1149 1150 config KPROBE_EVENT_GEN_TEST 1151 tristate "Test module for in-kernel kprobe event generation" 1152 depends on KPROBE_EVENTS && m 1153 help 1154 This option creates a test module to check the base 1155 functionality of in-kernel kprobe event definition. 1156 1157 To test, insert the module, and then check the trace buffer 1158 for the generated kprobe events. 1159 1160 If unsure, say N. 1161 1162 config HIST_TRIGGERS_DEBUG 1163 bool "Hist trigger debug support" 1164 depends on HIST_TRIGGERS 1165 help 1166 Add "hist_debug" file for each event, which when read will 1167 dump out a bunch of internal details about the hist triggers 1168 defined on that event. 1169 1170 The hist_debug file serves a couple of purposes: 1171 1172 - Helps developers verify that nothing is broken. 1173 1174 - Provides educational information to support the details 1175 of the hist trigger internals as described by 1176 Documentation/trace/histogram-design.rst. 1177 1178 The hist_debug output only covers the data structures 1179 related to the histogram definitions themselves and doesn't 1180 display the internals of map buckets or variable values of 1181 running histograms. 1182 1183 If unsure, say N. 1184 1185 source "kernel/trace/rv/Kconfig" 1186 1187 endif # FTRACE 1188