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