1# SPDX-License-Identifier: GPL-2.0-only 2menu "Kernel hacking" 3 4menu "printk and dmesg options" 5 6config PRINTK_TIME 7 bool "Show timing information on printks" 8 depends on PRINTK 9 help 10 Selecting this option causes time stamps of the printk() 11 messages to be added to the output of the syslog() system 12 call and at the console. 13 14 The timestamp is always recorded internally, and exported 15 to /dev/kmsg. This flag just specifies if the timestamp should 16 be included, not that the timestamp is recorded. 17 18 The behavior is also controlled by the kernel command line 19 parameter printk.time=1. See Documentation/admin-guide/kernel-parameters.rst 20 21config PRINTK_CALLER 22 bool "Show caller information on printks" 23 depends on PRINTK 24 help 25 Selecting this option causes printk() to add a caller "thread id" (if 26 in task context) or a caller "processor id" (if not in task context) 27 to every message. 28 29 This option is intended for environments where multiple threads 30 concurrently call printk() for many times, for it is difficult to 31 interpret without knowing where these lines (or sometimes individual 32 line which was divided into multiple lines due to race) came from. 33 34 Since toggling after boot makes the code racy, currently there is 35 no option to enable/disable at the kernel command line parameter or 36 sysfs interface. 37 38config CONSOLE_LOGLEVEL_DEFAULT 39 int "Default console loglevel (1-15)" 40 range 1 15 41 default "7" 42 help 43 Default loglevel to determine what will be printed on the console. 44 45 Setting a default here is equivalent to passing in loglevel=<x> in 46 the kernel bootargs. loglevel=<x> continues to override whatever 47 value is specified here as well. 48 49 Note: This does not affect the log level of un-prefixed printk() 50 usage in the kernel. That is controlled by the MESSAGE_LOGLEVEL_DEFAULT 51 option. 52 53config CONSOLE_LOGLEVEL_QUIET 54 int "quiet console loglevel (1-15)" 55 range 1 15 56 default "4" 57 help 58 loglevel to use when "quiet" is passed on the kernel commandline. 59 60 When "quiet" is passed on the kernel commandline this loglevel 61 will be used as the loglevel. IOW passing "quiet" will be the 62 equivalent of passing "loglevel=<CONSOLE_LOGLEVEL_QUIET>" 63 64config MESSAGE_LOGLEVEL_DEFAULT 65 int "Default message log level (1-7)" 66 range 1 7 67 default "4" 68 help 69 Default log level for printk statements with no specified priority. 70 71 This was hard-coded to KERN_WARNING since at least 2.6.10 but folks 72 that are auditing their logs closely may want to set it to a lower 73 priority. 74 75 Note: This does not affect what message level gets printed on the console 76 by default. To change that, use loglevel=<x> in the kernel bootargs, 77 or pick a different CONSOLE_LOGLEVEL_DEFAULT configuration value. 78 79config BOOT_PRINTK_DELAY 80 bool "Delay each boot printk message by N milliseconds" 81 depends on DEBUG_KERNEL && PRINTK && GENERIC_CALIBRATE_DELAY 82 help 83 This build option allows you to read kernel boot messages 84 by inserting a short delay after each one. The delay is 85 specified in milliseconds on the kernel command line, 86 using "boot_delay=N". 87 88 It is likely that you would also need to use "lpj=M" to preset 89 the "loops per jiffie" value. 90 See a previous boot log for the "lpj" value to use for your 91 system, and then set "lpj=M" before setting "boot_delay=N". 92 NOTE: Using this option may adversely affect SMP systems. 93 I.e., processors other than the first one may not boot up. 94 BOOT_PRINTK_DELAY also may cause LOCKUP_DETECTOR to detect 95 what it believes to be lockup conditions. 96 97config DYNAMIC_DEBUG 98 bool "Enable dynamic printk() support" 99 default n 100 depends on PRINTK 101 depends on (DEBUG_FS || PROC_FS) 102 select DYNAMIC_DEBUG_CORE 103 help 104 105 Compiles debug level messages into the kernel, which would not 106 otherwise be available at runtime. These messages can then be 107 enabled/disabled based on various levels of scope - per source file, 108 function, module, format string, and line number. This mechanism 109 implicitly compiles in all pr_debug() and dev_dbg() calls, which 110 enlarges the kernel text size by about 2%. 111 112 If a source file is compiled with DEBUG flag set, any 113 pr_debug() calls in it are enabled by default, but can be 114 disabled at runtime as below. Note that DEBUG flag is 115 turned on by many CONFIG_*DEBUG* options. 116 117 Usage: 118 119 Dynamic debugging is controlled via the 'dynamic_debug/control' file, 120 which is contained in the 'debugfs' filesystem or procfs. 121 Thus, the debugfs or procfs filesystem must first be mounted before 122 making use of this feature. 123 We refer the control file as: <debugfs>/dynamic_debug/control. This 124 file contains a list of the debug statements that can be enabled. The 125 format for each line of the file is: 126 127 filename:lineno [module]function flags format 128 129 filename : source file of the debug statement 130 lineno : line number of the debug statement 131 module : module that contains the debug statement 132 function : function that contains the debug statement 133 flags : '=p' means the line is turned 'on' for printing 134 format : the format used for the debug statement 135 136 From a live system: 137 138 nullarbor:~ # cat <debugfs>/dynamic_debug/control 139 # filename:lineno [module]function flags format 140 fs/aio.c:222 [aio]__put_ioctx =_ "__put_ioctx:\040freeing\040%p\012" 141 fs/aio.c:248 [aio]ioctx_alloc =_ "ENOMEM:\040nr_events\040too\040high\012" 142 fs/aio.c:1770 [aio]sys_io_cancel =_ "calling\040cancel\012" 143 144 Example usage: 145 146 // enable the message at line 1603 of file svcsock.c 147 nullarbor:~ # echo -n 'file svcsock.c line 1603 +p' > 148 <debugfs>/dynamic_debug/control 149 150 // enable all the messages in file svcsock.c 151 nullarbor:~ # echo -n 'file svcsock.c +p' > 152 <debugfs>/dynamic_debug/control 153 154 // enable all the messages in the NFS server module 155 nullarbor:~ # echo -n 'module nfsd +p' > 156 <debugfs>/dynamic_debug/control 157 158 // enable all 12 messages in the function svc_process() 159 nullarbor:~ # echo -n 'func svc_process +p' > 160 <debugfs>/dynamic_debug/control 161 162 // disable all 12 messages in the function svc_process() 163 nullarbor:~ # echo -n 'func svc_process -p' > 164 <debugfs>/dynamic_debug/control 165 166 See Documentation/admin-guide/dynamic-debug-howto.rst for additional 167 information. 168 169config DYNAMIC_DEBUG_CORE 170 bool "Enable core function of dynamic debug support" 171 depends on PRINTK 172 depends on (DEBUG_FS || PROC_FS) 173 help 174 Enable core functional support of dynamic debug. It is useful 175 when you want to tie dynamic debug to your kernel modules with 176 DYNAMIC_DEBUG_MODULE defined for each of them, especially for 177 the case of embedded system where the kernel image size is 178 sensitive for people. 179 180config SYMBOLIC_ERRNAME 181 bool "Support symbolic error names in printf" 182 default y if PRINTK 183 help 184 If you say Y here, the kernel's printf implementation will 185 be able to print symbolic error names such as ENOSPC instead 186 of the number 28. It makes the kernel image slightly larger 187 (about 3KB), but can make the kernel logs easier to read. 188 189config DEBUG_BUGVERBOSE 190 bool "Verbose BUG() reporting (adds 70K)" if DEBUG_KERNEL && EXPERT 191 depends on BUG && (GENERIC_BUG || HAVE_DEBUG_BUGVERBOSE) 192 default y 193 help 194 Say Y here to make BUG() panics output the file name and line number 195 of the BUG call as well as the EIP and oops trace. This aids 196 debugging but costs about 70-100K of memory. 197 198endmenu # "printk and dmesg options" 199 200menu "Compile-time checks and compiler options" 201 202config DEBUG_INFO 203 bool "Compile the kernel with debug info" 204 depends on DEBUG_KERNEL && !COMPILE_TEST 205 help 206 If you say Y here the resulting kernel image will include 207 debugging info resulting in a larger kernel image. 208 This adds debug symbols to the kernel and modules (gcc -g), and 209 is needed if you intend to use kernel crashdump or binary object 210 tools like crash, kgdb, LKCD, gdb, etc on the kernel. 211 Say Y here only if you plan to debug the kernel. 212 213 If unsure, say N. 214 215if DEBUG_INFO 216 217config DEBUG_INFO_REDUCED 218 bool "Reduce debugging information" 219 help 220 If you say Y here gcc is instructed to generate less debugging 221 information for structure types. This means that tools that 222 need full debugging information (like kgdb or systemtap) won't 223 be happy. But if you merely need debugging information to 224 resolve line numbers there is no loss. Advantage is that 225 build directory object sizes shrink dramatically over a full 226 DEBUG_INFO build and compile times are reduced too. 227 Only works with newer gcc versions. 228 229config DEBUG_INFO_COMPRESSED 230 bool "Compressed debugging information" 231 depends on $(cc-option,-gz=zlib) 232 depends on $(ld-option,--compress-debug-sections=zlib) 233 help 234 Compress the debug information using zlib. Requires GCC 5.0+ or Clang 235 5.0+, binutils 2.26+, and zlib. 236 237 Users of dpkg-deb via scripts/package/builddeb may find an increase in 238 size of their debug .deb packages with this config set, due to the 239 debug info being compressed with zlib, then the object files being 240 recompressed with a different compression scheme. But this is still 241 preferable to setting $KDEB_COMPRESS to "none" which would be even 242 larger. 243 244config DEBUG_INFO_SPLIT 245 bool "Produce split debuginfo in .dwo files" 246 depends on $(cc-option,-gsplit-dwarf) 247 help 248 Generate debug info into separate .dwo files. This significantly 249 reduces the build directory size for builds with DEBUG_INFO, 250 because it stores the information only once on disk in .dwo 251 files instead of multiple times in object files and executables. 252 In addition the debug information is also compressed. 253 254 Requires recent gcc (4.7+) and recent gdb/binutils. 255 Any tool that packages or reads debug information would need 256 to know about the .dwo files and include them. 257 Incompatible with older versions of ccache. 258 259config DEBUG_INFO_DWARF4 260 bool "Generate dwarf4 debuginfo" 261 help 262 Generate dwarf4 debug info. This requires recent versions 263 of gcc and gdb. It makes the debug information larger. 264 But it significantly improves the success of resolving 265 variables in gdb on optimized code. 266 267config DEBUG_INFO_BTF 268 bool "Generate BTF typeinfo" 269 depends on !DEBUG_INFO_SPLIT && !DEBUG_INFO_REDUCED 270 depends on !GCC_PLUGIN_RANDSTRUCT || COMPILE_TEST 271 help 272 Generate deduplicated BTF type information from DWARF debug info. 273 Turning this on expects presence of pahole tool, which will convert 274 DWARF type info into equivalent deduplicated BTF type info. 275 276config PAHOLE_HAS_SPLIT_BTF 277 def_bool $(success, test `$(PAHOLE) --version | sed -E 's/v([0-9]+)\.([0-9]+)/\1\2/'` -ge "119") 278 279config DEBUG_INFO_BTF_MODULES 280 def_bool y 281 depends on DEBUG_INFO_BTF && MODULES && PAHOLE_HAS_SPLIT_BTF 282 help 283 Generate compact split BTF type information for kernel modules. 284 285config GDB_SCRIPTS 286 bool "Provide GDB scripts for kernel debugging" 287 help 288 This creates the required links to GDB helper scripts in the 289 build directory. If you load vmlinux into gdb, the helper 290 scripts will be automatically imported by gdb as well, and 291 additional functions are available to analyze a Linux kernel 292 instance. See Documentation/dev-tools/gdb-kernel-debugging.rst 293 for further details. 294 295endif # DEBUG_INFO 296 297config FRAME_WARN 298 int "Warn for stack frames larger than" 299 range 0 8192 300 default 2048 if GCC_PLUGIN_LATENT_ENTROPY 301 default 1280 if (!64BIT && PARISC) 302 default 1024 if (!64BIT && !PARISC) 303 default 2048 if 64BIT 304 help 305 Tell gcc to warn at build time for stack frames larger than this. 306 Setting this too low will cause a lot of warnings. 307 Setting it to 0 disables the warning. 308 309config STRIP_ASM_SYMS 310 bool "Strip assembler-generated symbols during link" 311 default n 312 help 313 Strip internal assembler-generated symbols during a link (symbols 314 that look like '.Lxxx') so they don't pollute the output of 315 get_wchan() and suchlike. 316 317config READABLE_ASM 318 bool "Generate readable assembler code" 319 depends on DEBUG_KERNEL 320 help 321 Disable some compiler optimizations that tend to generate human unreadable 322 assembler output. This may make the kernel slightly slower, but it helps 323 to keep kernel developers who have to stare a lot at assembler listings 324 sane. 325 326config HEADERS_INSTALL 327 bool "Install uapi headers to usr/include" 328 depends on !UML 329 help 330 This option will install uapi headers (headers exported to user-space) 331 into the usr/include directory for use during the kernel build. 332 This is unneeded for building the kernel itself, but needed for some 333 user-space program samples. It is also needed by some features such 334 as uapi header sanity checks. 335 336config DEBUG_SECTION_MISMATCH 337 bool "Enable full Section mismatch analysis" 338 help 339 The section mismatch analysis checks if there are illegal 340 references from one section to another section. 341 During linktime or runtime, some sections are dropped; 342 any use of code/data previously in these sections would 343 most likely result in an oops. 344 In the code, functions and variables are annotated with 345 __init,, etc. (see the full list in include/linux/init.h), 346 which results in the code/data being placed in specific sections. 347 The section mismatch analysis is always performed after a full 348 kernel build, and enabling this option causes the following 349 additional step to occur: 350 - Add the option -fno-inline-functions-called-once to gcc commands. 351 When inlining a function annotated with __init in a non-init 352 function, we would lose the section information and thus 353 the analysis would not catch the illegal reference. 354 This option tells gcc to inline less (but it does result in 355 a larger kernel). 356 357config SECTION_MISMATCH_WARN_ONLY 358 bool "Make section mismatch errors non-fatal" 359 default y 360 help 361 If you say N here, the build process will fail if there are any 362 section mismatch, instead of just throwing warnings. 363 364 If unsure, say Y. 365 366config DEBUG_FORCE_FUNCTION_ALIGN_32B 367 bool "Force all function address 32B aligned" if EXPERT 368 help 369 There are cases that a commit from one domain changes the function 370 address alignment of other domains, and cause magic performance 371 bump (regression or improvement). Enable this option will help to 372 verify if the bump is caused by function alignment changes, while 373 it will slightly increase the kernel size and affect icache usage. 374 375 It is mainly for debug and performance tuning use. 376 377# 378# Select this config option from the architecture Kconfig, if it 379# is preferred to always offer frame pointers as a config 380# option on the architecture (regardless of KERNEL_DEBUG): 381# 382config ARCH_WANT_FRAME_POINTERS 383 bool 384 385config FRAME_POINTER 386 bool "Compile the kernel with frame pointers" 387 depends on DEBUG_KERNEL && (M68K || UML || SUPERH) || ARCH_WANT_FRAME_POINTERS 388 default y if (DEBUG_INFO && UML) || ARCH_WANT_FRAME_POINTERS 389 help 390 If you say Y here the resulting kernel image will be slightly 391 larger and slower, but it gives very useful debugging information 392 in case of kernel bugs. (precise oopses/stacktraces/warnings) 393 394config STACK_VALIDATION 395 bool "Compile-time stack metadata validation" 396 depends on HAVE_STACK_VALIDATION 397 default n 398 help 399 Add compile-time checks to validate stack metadata, including frame 400 pointers (if CONFIG_FRAME_POINTER is enabled). This helps ensure 401 that runtime stack traces are more reliable. 402 403 This is also a prerequisite for generation of ORC unwind data, which 404 is needed for CONFIG_UNWINDER_ORC. 405 406 For more information, see 407 tools/objtool/Documentation/stack-validation.txt. 408 409config VMLINUX_VALIDATION 410 bool 411 depends on STACK_VALIDATION && DEBUG_ENTRY && !PARAVIRT 412 default y 413 414config DEBUG_FORCE_WEAK_PER_CPU 415 bool "Force weak per-cpu definitions" 416 depends on DEBUG_KERNEL 417 help 418 s390 and alpha require percpu variables in modules to be 419 defined weak to work around addressing range issue which 420 puts the following two restrictions on percpu variable 421 definitions. 422 423 1. percpu symbols must be unique whether static or not 424 2. percpu variables can't be defined inside a function 425 426 To ensure that generic code follows the above rules, this 427 option forces all percpu variables to be defined as weak. 428 429endmenu # "Compiler options" 430 431menu "Generic Kernel Debugging Instruments" 432 433config MAGIC_SYSRQ 434 bool "Magic SysRq key" 435 depends on !UML 436 help 437 If you say Y here, you will have some control over the system even 438 if the system crashes for example during kernel debugging (e.g., you 439 will be able to flush the buffer cache to disk, reboot the system 440 immediately or dump some status information). This is accomplished 441 by pressing various keys while holding SysRq (Alt+PrintScreen). It 442 also works on a serial console (on PC hardware at least), if you 443 send a BREAK and then within 5 seconds a command keypress. The 444 keys are documented in <file:Documentation/admin-guide/sysrq.rst>. 445 Don't say Y unless you really know what this hack does. 446 447config MAGIC_SYSRQ_DEFAULT_ENABLE 448 hex "Enable magic SysRq key functions by default" 449 depends on MAGIC_SYSRQ 450 default 0x1 451 help 452 Specifies which SysRq key functions are enabled by default. 453 This may be set to 1 or 0 to enable or disable them all, or 454 to a bitmask as described in Documentation/admin-guide/sysrq.rst. 455 456config MAGIC_SYSRQ_SERIAL 457 bool "Enable magic SysRq key over serial" 458 depends on MAGIC_SYSRQ 459 default y 460 help 461 Many embedded boards have a disconnected TTL level serial which can 462 generate some garbage that can lead to spurious false sysrq detects. 463 This option allows you to decide whether you want to enable the 464 magic SysRq key. 465 466config MAGIC_SYSRQ_SERIAL_SEQUENCE 467 string "Char sequence that enables magic SysRq over serial" 468 depends on MAGIC_SYSRQ_SERIAL 469 default "" 470 help 471 Specifies a sequence of characters that can follow BREAK to enable 472 SysRq on a serial console. 473 474 If unsure, leave an empty string and the option will not be enabled. 475 476config DEBUG_FS 477 bool "Debug Filesystem" 478 help 479 debugfs is a virtual file system that kernel developers use to put 480 debugging files into. Enable this option to be able to read and 481 write to these files. 482 483 For detailed documentation on the debugfs API, see 484 Documentation/filesystems/. 485 486 If unsure, say N. 487 488choice 489 prompt "Debugfs default access" 490 depends on DEBUG_FS 491 default DEBUG_FS_ALLOW_ALL 492 help 493 This selects the default access restrictions for debugfs. 494 It can be overridden with kernel command line option 495 debugfs=[on,no-mount,off]. The restrictions apply for API access 496 and filesystem registration. 497 498config DEBUG_FS_ALLOW_ALL 499 bool "Access normal" 500 help 501 No restrictions apply. Both API and filesystem registration 502 is on. This is the normal default operation. 503 504config DEBUG_FS_DISALLOW_MOUNT 505 bool "Do not register debugfs as filesystem" 506 help 507 The API is open but filesystem is not loaded. Clients can still do 508 their work and read with debug tools that do not need 509 debugfs filesystem. 510 511config DEBUG_FS_ALLOW_NONE 512 bool "No access" 513 help 514 Access is off. Clients get -PERM when trying to create nodes in 515 debugfs tree and debugfs is not registered as a filesystem. 516 Client can then back-off or continue without debugfs access. 517 518endchoice 519 520source "lib/Kconfig.kgdb" 521source "lib/Kconfig.ubsan" 522source "lib/Kconfig.kcsan" 523 524endmenu 525 526config DEBUG_KERNEL 527 bool "Kernel debugging" 528 help 529 Say Y here if you are developing drivers or trying to debug and 530 identify kernel problems. 531 532config DEBUG_MISC 533 bool "Miscellaneous debug code" 534 default DEBUG_KERNEL 535 depends on DEBUG_KERNEL 536 help 537 Say Y here if you need to enable miscellaneous debug code that should 538 be under a more specific debug option but isn't. 539 540 541menu "Memory Debugging" 542 543source "mm/Kconfig.debug" 544 545config DEBUG_OBJECTS 546 bool "Debug object operations" 547 depends on DEBUG_KERNEL 548 help 549 If you say Y here, additional code will be inserted into the 550 kernel to track the life time of various objects and validate 551 the operations on those objects. 552 553config DEBUG_OBJECTS_SELFTEST 554 bool "Debug objects selftest" 555 depends on DEBUG_OBJECTS 556 help 557 This enables the selftest of the object debug code. 558 559config DEBUG_OBJECTS_FREE 560 bool "Debug objects in freed memory" 561 depends on DEBUG_OBJECTS 562 help 563 This enables checks whether a k/v free operation frees an area 564 which contains an object which has not been deactivated 565 properly. This can make kmalloc/kfree-intensive workloads 566 much slower. 567 568config DEBUG_OBJECTS_TIMERS 569 bool "Debug timer objects" 570 depends on DEBUG_OBJECTS 571 help 572 If you say Y here, additional code will be inserted into the 573 timer routines to track the life time of timer objects and 574 validate the timer operations. 575 576config DEBUG_OBJECTS_WORK 577 bool "Debug work objects" 578 depends on DEBUG_OBJECTS 579 help 580 If you say Y here, additional code will be inserted into the 581 work queue routines to track the life time of work objects and 582 validate the work operations. 583 584config DEBUG_OBJECTS_RCU_HEAD 585 bool "Debug RCU callbacks objects" 586 depends on DEBUG_OBJECTS 587 help 588 Enable this to turn on debugging of RCU list heads (call_rcu() usage). 589 590config DEBUG_OBJECTS_PERCPU_COUNTER 591 bool "Debug percpu counter objects" 592 depends on DEBUG_OBJECTS 593 help 594 If you say Y here, additional code will be inserted into the 595 percpu counter routines to track the life time of percpu counter 596 objects and validate the percpu counter operations. 597 598config DEBUG_OBJECTS_ENABLE_DEFAULT 599 int "debug_objects bootup default value (0-1)" 600 range 0 1 601 default "1" 602 depends on DEBUG_OBJECTS 603 help 604 Debug objects boot parameter default value 605 606config DEBUG_SLAB 607 bool "Debug slab memory allocations" 608 depends on DEBUG_KERNEL && SLAB 609 help 610 Say Y here to have the kernel do limited verification on memory 611 allocation as well as poisoning memory on free to catch use of freed 612 memory. This can make kmalloc/kfree-intensive workloads much slower. 613 614config SLUB_DEBUG_ON 615 bool "SLUB debugging on by default" 616 depends on SLUB && SLUB_DEBUG 617 default n 618 help 619 Boot with debugging on by default. SLUB boots by default with 620 the runtime debug capabilities switched off. Enabling this is 621 equivalent to specifying the "slub_debug" parameter on boot. 622 There is no support for more fine grained debug control like 623 possible with slub_debug=xxx. SLUB debugging may be switched 624 off in a kernel built with CONFIG_SLUB_DEBUG_ON by specifying 625 "slub_debug=-". 626 627config SLUB_STATS 628 default n 629 bool "Enable SLUB performance statistics" 630 depends on SLUB && SYSFS 631 help 632 SLUB statistics are useful to debug SLUBs allocation behavior in 633 order find ways to optimize the allocator. This should never be 634 enabled for production use since keeping statistics slows down 635 the allocator by a few percentage points. The slabinfo command 636 supports the determination of the most active slabs to figure 637 out which slabs are relevant to a particular load. 638 Try running: slabinfo -DA 639 640config HAVE_DEBUG_KMEMLEAK 641 bool 642 643config DEBUG_KMEMLEAK 644 bool "Kernel memory leak detector" 645 depends on DEBUG_KERNEL && HAVE_DEBUG_KMEMLEAK 646 select DEBUG_FS 647 select STACKTRACE if STACKTRACE_SUPPORT 648 select KALLSYMS 649 select CRC32 650 help 651 Say Y here if you want to enable the memory leak 652 detector. The memory allocation/freeing is traced in a way 653 similar to the Boehm's conservative garbage collector, the 654 difference being that the orphan objects are not freed but 655 only shown in /sys/kernel/debug/kmemleak. Enabling this 656 feature will introduce an overhead to memory 657 allocations. See Documentation/dev-tools/kmemleak.rst for more 658 details. 659 660 Enabling DEBUG_SLAB or SLUB_DEBUG may increase the chances 661 of finding leaks due to the slab objects poisoning. 662 663 In order to access the kmemleak file, debugfs needs to be 664 mounted (usually at /sys/kernel/debug). 665 666config DEBUG_KMEMLEAK_MEM_POOL_SIZE 667 int "Kmemleak memory pool size" 668 depends on DEBUG_KMEMLEAK 669 range 200 1000000 670 default 16000 671 help 672 Kmemleak must track all the memory allocations to avoid 673 reporting false positives. Since memory may be allocated or 674 freed before kmemleak is fully initialised, use a static pool 675 of metadata objects to track such callbacks. After kmemleak is 676 fully initialised, this memory pool acts as an emergency one 677 if slab allocations fail. 678 679config DEBUG_KMEMLEAK_TEST 680 tristate "Simple test for the kernel memory leak detector" 681 depends on DEBUG_KMEMLEAK && m 682 help 683 This option enables a module that explicitly leaks memory. 684 685 If unsure, say N. 686 687config DEBUG_KMEMLEAK_DEFAULT_OFF 688 bool "Default kmemleak to off" 689 depends on DEBUG_KMEMLEAK 690 help 691 Say Y here to disable kmemleak by default. It can then be enabled 692 on the command line via kmemleak=on. 693 694config DEBUG_KMEMLEAK_AUTO_SCAN 695 bool "Enable kmemleak auto scan thread on boot up" 696 default y 697 depends on DEBUG_KMEMLEAK 698 help 699 Depending on the cpu, kmemleak scan may be cpu intensive and can 700 stall user tasks at times. This option enables/disables automatic 701 kmemleak scan at boot up. 702 703 Say N here to disable kmemleak auto scan thread to stop automatic 704 scanning. Disabling this option disables automatic reporting of 705 memory leaks. 706 707 If unsure, say Y. 708 709config DEBUG_STACK_USAGE 710 bool "Stack utilization instrumentation" 711 depends on DEBUG_KERNEL && !IA64 712 help 713 Enables the display of the minimum amount of free stack which each 714 task has ever had available in the sysrq-T and sysrq-P debug output. 715 716 This option will slow down process creation somewhat. 717 718config SCHED_STACK_END_CHECK 719 bool "Detect stack corruption on calls to schedule()" 720 depends on DEBUG_KERNEL 721 default n 722 help 723 This option checks for a stack overrun on calls to schedule(). 724 If the stack end location is found to be over written always panic as 725 the content of the corrupted region can no longer be trusted. 726 This is to ensure no erroneous behaviour occurs which could result in 727 data corruption or a sporadic crash at a later stage once the region 728 is examined. The runtime overhead introduced is minimal. 729 730config ARCH_HAS_DEBUG_VM_PGTABLE 731 bool 732 help 733 An architecture should select this when it can successfully 734 build and run DEBUG_VM_PGTABLE. 735 736config DEBUG_VM 737 bool "Debug VM" 738 depends on DEBUG_KERNEL 739 help 740 Enable this to turn on extended checks in the virtual-memory system 741 that may impact performance. 742 743 If unsure, say N. 744 745config DEBUG_VM_VMACACHE 746 bool "Debug VMA caching" 747 depends on DEBUG_VM 748 help 749 Enable this to turn on VMA caching debug information. Doing so 750 can cause significant overhead, so only enable it in non-production 751 environments. 752 753 If unsure, say N. 754 755config DEBUG_VM_RB 756 bool "Debug VM red-black trees" 757 depends on DEBUG_VM 758 help 759 Enable VM red-black tree debugging information and extra validations. 760 761 If unsure, say N. 762 763config DEBUG_VM_PGFLAGS 764 bool "Debug page-flags operations" 765 depends on DEBUG_VM 766 help 767 Enables extra validation on page flags operations. 768 769 If unsure, say N. 770 771config DEBUG_VM_PGTABLE 772 bool "Debug arch page table for semantics compliance" 773 depends on MMU 774 depends on ARCH_HAS_DEBUG_VM_PGTABLE 775 default y if DEBUG_VM 776 help 777 This option provides a debug method which can be used to test 778 architecture page table helper functions on various platforms in 779 verifying if they comply with expected generic MM semantics. This 780 will help architecture code in making sure that any changes or 781 new additions of these helpers still conform to expected 782 semantics of the generic MM. Platforms will have to opt in for 783 this through ARCH_HAS_DEBUG_VM_PGTABLE. 784 785 If unsure, say N. 786 787config ARCH_HAS_DEBUG_VIRTUAL 788 bool 789 790config DEBUG_VIRTUAL 791 bool "Debug VM translations" 792 depends on DEBUG_KERNEL && ARCH_HAS_DEBUG_VIRTUAL 793 help 794 Enable some costly sanity checks in virtual to page code. This can 795 catch mistakes with virt_to_page() and friends. 796 797 If unsure, say N. 798 799config DEBUG_NOMMU_REGIONS 800 bool "Debug the global anon/private NOMMU mapping region tree" 801 depends on DEBUG_KERNEL && !MMU 802 help 803 This option causes the global tree of anonymous and private mapping 804 regions to be regularly checked for invalid topology. 805 806config DEBUG_MEMORY_INIT 807 bool "Debug memory initialisation" if EXPERT 808 default !EXPERT 809 help 810 Enable this for additional checks during memory initialisation. 811 The sanity checks verify aspects of the VM such as the memory model 812 and other information provided by the architecture. Verbose 813 information will be printed at KERN_DEBUG loglevel depending 814 on the mminit_loglevel= command-line option. 815 816 If unsure, say Y 817 818config MEMORY_NOTIFIER_ERROR_INJECT 819 tristate "Memory hotplug notifier error injection module" 820 depends on MEMORY_HOTPLUG_SPARSE && NOTIFIER_ERROR_INJECTION 821 help 822 This option provides the ability to inject artificial errors to 823 memory hotplug notifier chain callbacks. It is controlled through 824 debugfs interface under /sys/kernel/debug/notifier-error-inject/memory 825 826 If the notifier call chain should be failed with some events 827 notified, write the error code to "actions/<notifier event>/error". 828 829 Example: Inject memory hotplug offline error (-12 == -ENOMEM) 830 831 # cd /sys/kernel/debug/notifier-error-inject/memory 832 # echo -12 > actions/MEM_GOING_OFFLINE/error 833 # echo offline > /sys/devices/system/memory/memoryXXX/state 834 bash: echo: write error: Cannot allocate memory 835 836 To compile this code as a module, choose M here: the module will 837 be called memory-notifier-error-inject. 838 839 If unsure, say N. 840 841config DEBUG_PER_CPU_MAPS 842 bool "Debug access to per_cpu maps" 843 depends on DEBUG_KERNEL 844 depends on SMP 845 help 846 Say Y to verify that the per_cpu map being accessed has 847 been set up. This adds a fair amount of code to kernel memory 848 and decreases performance. 849 850 Say N if unsure. 851 852config DEBUG_KMAP_LOCAL 853 bool "Debug kmap_local temporary mappings" 854 depends on DEBUG_KERNEL && KMAP_LOCAL 855 help 856 This option enables additional error checking for the kmap_local 857 infrastructure. Disable for production use. 858 859config ARCH_SUPPORTS_KMAP_LOCAL_FORCE_MAP 860 bool 861 862config DEBUG_KMAP_LOCAL_FORCE_MAP 863 bool "Enforce kmap_local temporary mappings" 864 depends on DEBUG_KERNEL && ARCH_SUPPORTS_KMAP_LOCAL_FORCE_MAP 865 select KMAP_LOCAL 866 select DEBUG_KMAP_LOCAL 867 help 868 This option enforces temporary mappings through the kmap_local 869 mechanism for non-highmem pages and on non-highmem systems. 870 Disable this for production systems! 871 872config DEBUG_HIGHMEM 873 bool "Highmem debugging" 874 depends on DEBUG_KERNEL && HIGHMEM 875 select DEBUG_KMAP_LOCAL_FORCE_MAP if ARCH_SUPPORTS_KMAP_LOCAL_FORCE_MAP 876 select DEBUG_KMAP_LOCAL 877 help 878 This option enables additional error checking for high memory 879 systems. Disable for production systems. 880 881config HAVE_DEBUG_STACKOVERFLOW 882 bool 883 884config DEBUG_STACKOVERFLOW 885 bool "Check for stack overflows" 886 depends on DEBUG_KERNEL && HAVE_DEBUG_STACKOVERFLOW 887 help 888 Say Y here if you want to check for overflows of kernel, IRQ 889 and exception stacks (if your architecture uses them). This 890 option will show detailed messages if free stack space drops 891 below a certain limit. 892 893 These kinds of bugs usually occur when call-chains in the 894 kernel get too deep, especially when interrupts are 895 involved. 896 897 Use this in cases where you see apparently random memory 898 corruption, especially if it appears in 'struct thread_info' 899 900 If in doubt, say "N". 901 902source "lib/Kconfig.kasan" 903 904endmenu # "Memory Debugging" 905 906config DEBUG_SHIRQ 907 bool "Debug shared IRQ handlers" 908 depends on DEBUG_KERNEL 909 help 910 Enable this to generate a spurious interrupt just before a shared 911 interrupt handler is deregistered (generating one when registering 912 is currently disabled). Drivers need to handle this correctly. Some 913 don't and need to be caught. 914 915menu "Debug Oops, Lockups and Hangs" 916 917config PANIC_ON_OOPS 918 bool "Panic on Oops" 919 help 920 Say Y here to enable the kernel to panic when it oopses. This 921 has the same effect as setting oops=panic on the kernel command 922 line. 923 924 This feature is useful to ensure that the kernel does not do 925 anything erroneous after an oops which could result in data 926 corruption or other issues. 927 928 Say N if unsure. 929 930config PANIC_ON_OOPS_VALUE 931 int 932 range 0 1 933 default 0 if !PANIC_ON_OOPS 934 default 1 if PANIC_ON_OOPS 935 936config PANIC_TIMEOUT 937 int "panic timeout" 938 default 0 939 help 940 Set the timeout value (in seconds) until a reboot occurs when 941 the kernel panics. If n = 0, then we wait forever. A timeout 942 value n > 0 will wait n seconds before rebooting, while a timeout 943 value n < 0 will reboot immediately. 944 945config LOCKUP_DETECTOR 946 bool 947 948config SOFTLOCKUP_DETECTOR 949 bool "Detect Soft Lockups" 950 depends on DEBUG_KERNEL && !S390 951 select LOCKUP_DETECTOR 952 help 953 Say Y here to enable the kernel to act as a watchdog to detect 954 soft lockups. 955 956 Softlockups are bugs that cause the kernel to loop in kernel 957 mode for more than 20 seconds, without giving other tasks a 958 chance to run. The current stack trace is displayed upon 959 detection and the system will stay locked up. 960 961config BOOTPARAM_SOFTLOCKUP_PANIC 962 bool "Panic (Reboot) On Soft Lockups" 963 depends on SOFTLOCKUP_DETECTOR 964 help 965 Say Y here to enable the kernel to panic on "soft lockups", 966 which are bugs that cause the kernel to loop in kernel 967 mode for more than 20 seconds (configurable using the watchdog_thresh 968 sysctl), without giving other tasks a chance to run. 969 970 The panic can be used in combination with panic_timeout, 971 to cause the system to reboot automatically after a 972 lockup has been detected. This feature is useful for 973 high-availability systems that have uptime guarantees and 974 where a lockup must be resolved ASAP. 975 976 Say N if unsure. 977 978config BOOTPARAM_SOFTLOCKUP_PANIC_VALUE 979 int 980 depends on SOFTLOCKUP_DETECTOR 981 range 0 1 982 default 0 if !BOOTPARAM_SOFTLOCKUP_PANIC 983 default 1 if BOOTPARAM_SOFTLOCKUP_PANIC 984 985config HARDLOCKUP_DETECTOR_PERF 986 bool 987 select SOFTLOCKUP_DETECTOR 988 989# 990# Enables a timestamp based low pass filter to compensate for perf based 991# hard lockup detection which runs too fast due to turbo modes. 992# 993config HARDLOCKUP_CHECK_TIMESTAMP 994 bool 995 996# 997# arch/ can define HAVE_HARDLOCKUP_DETECTOR_ARCH to provide their own hard 998# lockup detector rather than the perf based detector. 999# 1000config HARDLOCKUP_DETECTOR 1001 bool "Detect Hard Lockups" 1002 depends on DEBUG_KERNEL && !S390 1003 depends on HAVE_HARDLOCKUP_DETECTOR_PERF || HAVE_HARDLOCKUP_DETECTOR_ARCH 1004 select LOCKUP_DETECTOR 1005 select HARDLOCKUP_DETECTOR_PERF if HAVE_HARDLOCKUP_DETECTOR_PERF 1006 select HARDLOCKUP_DETECTOR_ARCH if HAVE_HARDLOCKUP_DETECTOR_ARCH 1007 help 1008 Say Y here to enable the kernel to act as a watchdog to detect 1009 hard lockups. 1010 1011 Hardlockups are bugs that cause the CPU to loop in kernel mode 1012 for more than 10 seconds, without letting other interrupts have a 1013 chance to run. The current stack trace is displayed upon detection 1014 and the system will stay locked up. 1015 1016config BOOTPARAM_HARDLOCKUP_PANIC 1017 bool "Panic (Reboot) On Hard Lockups" 1018 depends on HARDLOCKUP_DETECTOR 1019 help 1020 Say Y here to enable the kernel to panic on "hard lockups", 1021 which are bugs that cause the kernel to loop in kernel 1022 mode with interrupts disabled for more than 10 seconds (configurable 1023 using the watchdog_thresh sysctl). 1024 1025 Say N if unsure. 1026 1027config BOOTPARAM_HARDLOCKUP_PANIC_VALUE 1028 int 1029 depends on HARDLOCKUP_DETECTOR 1030 range 0 1 1031 default 0 if !BOOTPARAM_HARDLOCKUP_PANIC 1032 default 1 if BOOTPARAM_HARDLOCKUP_PANIC 1033 1034config DETECT_HUNG_TASK 1035 bool "Detect Hung Tasks" 1036 depends on DEBUG_KERNEL 1037 default SOFTLOCKUP_DETECTOR 1038 help 1039 Say Y here to enable the kernel to detect "hung tasks", 1040 which are bugs that cause the task to be stuck in 1041 uninterruptible "D" state indefinitely. 1042 1043 When a hung task is detected, the kernel will print the 1044 current stack trace (which you should report), but the 1045 task will stay in uninterruptible state. If lockdep is 1046 enabled then all held locks will also be reported. This 1047 feature has negligible overhead. 1048 1049config DEFAULT_HUNG_TASK_TIMEOUT 1050 int "Default timeout for hung task detection (in seconds)" 1051 depends on DETECT_HUNG_TASK 1052 default 120 1053 help 1054 This option controls the default timeout (in seconds) used 1055 to determine when a task has become non-responsive and should 1056 be considered hung. 1057 1058 It can be adjusted at runtime via the kernel.hung_task_timeout_secs 1059 sysctl or by writing a value to 1060 /proc/sys/kernel/hung_task_timeout_secs. 1061 1062 A timeout of 0 disables the check. The default is two minutes. 1063 Keeping the default should be fine in most cases. 1064 1065config BOOTPARAM_HUNG_TASK_PANIC 1066 bool "Panic (Reboot) On Hung Tasks" 1067 depends on DETECT_HUNG_TASK 1068 help 1069 Say Y here to enable the kernel to panic on "hung tasks", 1070 which are bugs that cause the kernel to leave a task stuck 1071 in uninterruptible "D" state. 1072 1073 The panic can be used in combination with panic_timeout, 1074 to cause the system to reboot automatically after a 1075 hung task has been detected. This feature is useful for 1076 high-availability systems that have uptime guarantees and 1077 where a hung tasks must be resolved ASAP. 1078 1079 Say N if unsure. 1080 1081config BOOTPARAM_HUNG_TASK_PANIC_VALUE 1082 int 1083 depends on DETECT_HUNG_TASK 1084 range 0 1 1085 default 0 if !BOOTPARAM_HUNG_TASK_PANIC 1086 default 1 if BOOTPARAM_HUNG_TASK_PANIC 1087 1088config WQ_WATCHDOG 1089 bool "Detect Workqueue Stalls" 1090 depends on DEBUG_KERNEL 1091 help 1092 Say Y here to enable stall detection on workqueues. If a 1093 worker pool doesn't make forward progress on a pending work 1094 item for over a given amount of time, 30s by default, a 1095 warning message is printed along with dump of workqueue 1096 state. This can be configured through kernel parameter 1097 "workqueue.watchdog_thresh" and its sysfs counterpart. 1098 1099config TEST_LOCKUP 1100 tristate "Test module to generate lockups" 1101 depends on m 1102 help 1103 This builds the "test_lockup" module that helps to make sure 1104 that watchdogs and lockup detectors are working properly. 1105 1106 Depending on module parameters it could emulate soft or hard 1107 lockup, "hung task", or locking arbitrary lock for a long time. 1108 Also it could generate series of lockups with cooling-down periods. 1109 1110 If unsure, say N. 1111 1112endmenu # "Debug lockups and hangs" 1113 1114menu "Scheduler Debugging" 1115 1116config SCHED_DEBUG 1117 bool "Collect scheduler debugging info" 1118 depends on DEBUG_KERNEL && PROC_FS 1119 default y 1120 help 1121 If you say Y here, the /proc/sched_debug file will be provided 1122 that can help debug the scheduler. The runtime overhead of this 1123 option is minimal. 1124 1125config SCHED_INFO 1126 bool 1127 default n 1128 1129config SCHEDSTATS 1130 bool "Collect scheduler statistics" 1131 depends on DEBUG_KERNEL && PROC_FS 1132 select SCHED_INFO 1133 help 1134 If you say Y here, additional code will be inserted into the 1135 scheduler and related routines to collect statistics about 1136 scheduler behavior and provide them in /proc/schedstat. These 1137 stats may be useful for both tuning and debugging the scheduler 1138 If you aren't debugging the scheduler or trying to tune a specific 1139 application, you can say N to avoid the very slight overhead 1140 this adds. 1141 1142endmenu 1143 1144config DEBUG_TIMEKEEPING 1145 bool "Enable extra timekeeping sanity checking" 1146 help 1147 This option will enable additional timekeeping sanity checks 1148 which may be helpful when diagnosing issues where timekeeping 1149 problems are suspected. 1150 1151 This may include checks in the timekeeping hotpaths, so this 1152 option may have a (very small) performance impact to some 1153 workloads. 1154 1155 If unsure, say N. 1156 1157config DEBUG_PREEMPT 1158 bool "Debug preemptible kernel" 1159 depends on DEBUG_KERNEL && PREEMPTION && TRACE_IRQFLAGS_SUPPORT 1160 default y 1161 help 1162 If you say Y here then the kernel will use a debug variant of the 1163 commonly used smp_processor_id() function and will print warnings 1164 if kernel code uses it in a preemption-unsafe way. Also, the kernel 1165 will detect preemption count underflows. 1166 1167menu "Lock Debugging (spinlocks, mutexes, etc...)" 1168 1169config LOCK_DEBUGGING_SUPPORT 1170 bool 1171 depends on TRACE_IRQFLAGS_SUPPORT && STACKTRACE_SUPPORT && LOCKDEP_SUPPORT 1172 default y 1173 1174config PROVE_LOCKING 1175 bool "Lock debugging: prove locking correctness" 1176 depends on DEBUG_KERNEL && LOCK_DEBUGGING_SUPPORT 1177 select LOCKDEP 1178 select DEBUG_SPINLOCK 1179 select DEBUG_MUTEXES 1180 select DEBUG_RT_MUTEXES if RT_MUTEXES 1181 select DEBUG_RWSEMS 1182 select DEBUG_WW_MUTEX_SLOWPATH 1183 select DEBUG_LOCK_ALLOC 1184 select PREEMPT_COUNT if !ARCH_NO_PREEMPT 1185 select TRACE_IRQFLAGS 1186 default n 1187 help 1188 This feature enables the kernel to prove that all locking 1189 that occurs in the kernel runtime is mathematically 1190 correct: that under no circumstance could an arbitrary (and 1191 not yet triggered) combination of observed locking 1192 sequences (on an arbitrary number of CPUs, running an 1193 arbitrary number of tasks and interrupt contexts) cause a 1194 deadlock. 1195 1196 In short, this feature enables the kernel to report locking 1197 related deadlocks before they actually occur. 1198 1199 The proof does not depend on how hard and complex a 1200 deadlock scenario would be to trigger: how many 1201 participant CPUs, tasks and irq-contexts would be needed 1202 for it to trigger. The proof also does not depend on 1203 timing: if a race and a resulting deadlock is possible 1204 theoretically (no matter how unlikely the race scenario 1205 is), it will be proven so and will immediately be 1206 reported by the kernel (once the event is observed that 1207 makes the deadlock theoretically possible). 1208 1209 If a deadlock is impossible (i.e. the locking rules, as 1210 observed by the kernel, are mathematically correct), the 1211 kernel reports nothing. 1212 1213 NOTE: this feature can also be enabled for rwlocks, mutexes 1214 and rwsems - in which case all dependencies between these 1215 different locking variants are observed and mapped too, and 1216 the proof of observed correctness is also maintained for an 1217 arbitrary combination of these separate locking variants. 1218 1219 For more details, see Documentation/locking/lockdep-design.rst. 1220 1221config PROVE_RAW_LOCK_NESTING 1222 bool "Enable raw_spinlock - spinlock nesting checks" 1223 depends on PROVE_LOCKING 1224 default n 1225 help 1226 Enable the raw_spinlock vs. spinlock nesting checks which ensure 1227 that the lock nesting rules for PREEMPT_RT enabled kernels are 1228 not violated. 1229 1230 NOTE: There are known nesting problems. So if you enable this 1231 option expect lockdep splats until these problems have been fully 1232 addressed which is work in progress. This config switch allows to 1233 identify and analyze these problems. It will be removed and the 1234 check permanentely enabled once the main issues have been fixed. 1235 1236 If unsure, select N. 1237 1238config LOCK_STAT 1239 bool "Lock usage statistics" 1240 depends on DEBUG_KERNEL && LOCK_DEBUGGING_SUPPORT 1241 select LOCKDEP 1242 select DEBUG_SPINLOCK 1243 select DEBUG_MUTEXES 1244 select DEBUG_RT_MUTEXES if RT_MUTEXES 1245 select DEBUG_LOCK_ALLOC 1246 default n 1247 help 1248 This feature enables tracking lock contention points 1249 1250 For more details, see Documentation/locking/lockstat.rst 1251 1252 This also enables lock events required by "perf lock", 1253 subcommand of perf. 1254 If you want to use "perf lock", you also need to turn on 1255 CONFIG_EVENT_TRACING. 1256 1257 CONFIG_LOCK_STAT defines "contended" and "acquired" lock events. 1258 (CONFIG_LOCKDEP defines "acquire" and "release" events.) 1259 1260config DEBUG_RT_MUTEXES 1261 bool "RT Mutex debugging, deadlock detection" 1262 depends on DEBUG_KERNEL && RT_MUTEXES 1263 help 1264 This allows rt mutex semantics violations and rt mutex related 1265 deadlocks (lockups) to be detected and reported automatically. 1266 1267config DEBUG_SPINLOCK 1268 bool "Spinlock and rw-lock debugging: basic checks" 1269 depends on DEBUG_KERNEL 1270 select UNINLINE_SPIN_UNLOCK 1271 help 1272 Say Y here and build SMP to catch missing spinlock initialization 1273 and certain other kinds of spinlock errors commonly made. This is 1274 best used in conjunction with the NMI watchdog so that spinlock 1275 deadlocks are also debuggable. 1276 1277config DEBUG_MUTEXES 1278 bool "Mutex debugging: basic checks" 1279 depends on DEBUG_KERNEL 1280 help 1281 This feature allows mutex semantics violations to be detected and 1282 reported. 1283 1284config DEBUG_WW_MUTEX_SLOWPATH 1285 bool "Wait/wound mutex debugging: Slowpath testing" 1286 depends on DEBUG_KERNEL && LOCK_DEBUGGING_SUPPORT 1287 select DEBUG_LOCK_ALLOC 1288 select DEBUG_SPINLOCK 1289 select DEBUG_MUTEXES 1290 help 1291 This feature enables slowpath testing for w/w mutex users by 1292 injecting additional -EDEADLK wound/backoff cases. Together with 1293 the full mutex checks enabled with (CONFIG_PROVE_LOCKING) this 1294 will test all possible w/w mutex interface abuse with the 1295 exception of simply not acquiring all the required locks. 1296 Note that this feature can introduce significant overhead, so 1297 it really should not be enabled in a production or distro kernel, 1298 even a debug kernel. If you are a driver writer, enable it. If 1299 you are a distro, do not. 1300 1301config DEBUG_RWSEMS 1302 bool "RW Semaphore debugging: basic checks" 1303 depends on DEBUG_KERNEL 1304 help 1305 This debugging feature allows mismatched rw semaphore locks 1306 and unlocks to be detected and reported. 1307 1308config DEBUG_LOCK_ALLOC 1309 bool "Lock debugging: detect incorrect freeing of live locks" 1310 depends on DEBUG_KERNEL && LOCK_DEBUGGING_SUPPORT 1311 select DEBUG_SPINLOCK 1312 select DEBUG_MUTEXES 1313 select DEBUG_RT_MUTEXES if RT_MUTEXES 1314 select LOCKDEP 1315 help 1316 This feature will check whether any held lock (spinlock, rwlock, 1317 mutex or rwsem) is incorrectly freed by the kernel, via any of the 1318 memory-freeing routines (kfree(), kmem_cache_free(), free_pages(), 1319 vfree(), etc.), whether a live lock is incorrectly reinitialized via 1320 spin_lock_init()/mutex_init()/etc., or whether there is any lock 1321 held during task exit. 1322 1323config LOCKDEP 1324 bool 1325 depends on DEBUG_KERNEL && LOCK_DEBUGGING_SUPPORT 1326 select STACKTRACE 1327 select FRAME_POINTER if !MIPS && !PPC && !ARM && !S390 && !MICROBLAZE && !ARC && !X86 1328 select KALLSYMS 1329 select KALLSYMS_ALL 1330 1331config LOCKDEP_SMALL 1332 bool 1333 1334config DEBUG_LOCKDEP 1335 bool "Lock dependency engine debugging" 1336 depends on DEBUG_KERNEL && LOCKDEP 1337 help 1338 If you say Y here, the lock dependency engine will do 1339 additional runtime checks to debug itself, at the price 1340 of more runtime overhead. 1341 1342config DEBUG_ATOMIC_SLEEP 1343 bool "Sleep inside atomic section checking" 1344 select PREEMPT_COUNT 1345 depends on DEBUG_KERNEL 1346 depends on !ARCH_NO_PREEMPT 1347 help 1348 If you say Y here, various routines which may sleep will become very 1349 noisy if they are called inside atomic sections: when a spinlock is 1350 held, inside an rcu read side critical section, inside preempt disabled 1351 sections, inside an interrupt, etc... 1352 1353config DEBUG_LOCKING_API_SELFTESTS 1354 bool "Locking API boot-time self-tests" 1355 depends on DEBUG_KERNEL 1356 help 1357 Say Y here if you want the kernel to run a short self-test during 1358 bootup. The self-test checks whether common types of locking bugs 1359 are detected by debugging mechanisms or not. (if you disable 1360 lock debugging then those bugs wont be detected of course.) 1361 The following locking APIs are covered: spinlocks, rwlocks, 1362 mutexes and rwsems. 1363 1364config LOCK_TORTURE_TEST 1365 tristate "torture tests for locking" 1366 depends on DEBUG_KERNEL 1367 select TORTURE_TEST 1368 help 1369 This option provides a kernel module that runs torture tests 1370 on kernel locking primitives. The kernel module may be built 1371 after the fact on the running kernel to be tested, if desired. 1372 1373 Say Y here if you want kernel locking-primitive torture tests 1374 to be built into the kernel. 1375 Say M if you want these torture tests to build as a module. 1376 Say N if you are unsure. 1377 1378config WW_MUTEX_SELFTEST 1379 tristate "Wait/wound mutex selftests" 1380 help 1381 This option provides a kernel module that runs tests on the 1382 on the struct ww_mutex locking API. 1383 1384 It is recommended to enable DEBUG_WW_MUTEX_SLOWPATH in conjunction 1385 with this test harness. 1386 1387 Say M if you want these self tests to build as a module. 1388 Say N if you are unsure. 1389 1390config SCF_TORTURE_TEST 1391 tristate "torture tests for smp_call_function*()" 1392 depends on DEBUG_KERNEL 1393 select TORTURE_TEST 1394 help 1395 This option provides a kernel module that runs torture tests 1396 on the smp_call_function() family of primitives. The kernel 1397 module may be built after the fact on the running kernel to 1398 be tested, if desired. 1399 1400config CSD_LOCK_WAIT_DEBUG 1401 bool "Debugging for csd_lock_wait(), called from smp_call_function*()" 1402 depends on DEBUG_KERNEL 1403 depends on 64BIT 1404 default n 1405 help 1406 This option enables debug prints when CPUs are slow to respond 1407 to the smp_call_function*() IPI wrappers. These debug prints 1408 include the IPI handler function currently executing (if any) 1409 and relevant stack traces. 1410 1411endmenu # lock debugging 1412 1413config TRACE_IRQFLAGS 1414 depends on TRACE_IRQFLAGS_SUPPORT 1415 bool 1416 help 1417 Enables hooks to interrupt enabling and disabling for 1418 either tracing or lock debugging. 1419 1420config TRACE_IRQFLAGS_NMI 1421 def_bool y 1422 depends on TRACE_IRQFLAGS 1423 depends on TRACE_IRQFLAGS_NMI_SUPPORT 1424 1425config STACKTRACE 1426 bool "Stack backtrace support" 1427 depends on STACKTRACE_SUPPORT 1428 help 1429 This option causes the kernel to create a /proc/pid/stack for 1430 every process, showing its current stack trace. 1431 It is also used by various kernel debugging features that require 1432 stack trace generation. 1433 1434config WARN_ALL_UNSEEDED_RANDOM 1435 bool "Warn for all uses of unseeded randomness" 1436 default n 1437 help 1438 Some parts of the kernel contain bugs relating to their use of 1439 cryptographically secure random numbers before it's actually possible 1440 to generate those numbers securely. This setting ensures that these 1441 flaws don't go unnoticed, by enabling a message, should this ever 1442 occur. This will allow people with obscure setups to know when things 1443 are going wrong, so that they might contact developers about fixing 1444 it. 1445 1446 Unfortunately, on some models of some architectures getting 1447 a fully seeded CRNG is extremely difficult, and so this can 1448 result in dmesg getting spammed for a surprisingly long 1449 time. This is really bad from a security perspective, and 1450 so architecture maintainers really need to do what they can 1451 to get the CRNG seeded sooner after the system is booted. 1452 However, since users cannot do anything actionable to 1453 address this, by default the kernel will issue only a single 1454 warning for the first use of unseeded randomness. 1455 1456 Say Y here if you want to receive warnings for all uses of 1457 unseeded randomness. This will be of use primarily for 1458 those developers interested in improving the security of 1459 Linux kernels running on their architecture (or 1460 subarchitecture). 1461 1462config DEBUG_KOBJECT 1463 bool "kobject debugging" 1464 depends on DEBUG_KERNEL 1465 help 1466 If you say Y here, some extra kobject debugging messages will be sent 1467 to the syslog. 1468 1469config DEBUG_KOBJECT_RELEASE 1470 bool "kobject release debugging" 1471 depends on DEBUG_OBJECTS_TIMERS 1472 help 1473 kobjects are reference counted objects. This means that their 1474 last reference count put is not predictable, and the kobject can 1475 live on past the point at which a driver decides to drop it's 1476 initial reference to the kobject gained on allocation. An 1477 example of this would be a struct device which has just been 1478 unregistered. 1479 1480 However, some buggy drivers assume that after such an operation, 1481 the memory backing the kobject can be immediately freed. This 1482 goes completely against the principles of a refcounted object. 1483 1484 If you say Y here, the kernel will delay the release of kobjects 1485 on the last reference count to improve the visibility of this 1486 kind of kobject release bug. 1487 1488config HAVE_DEBUG_BUGVERBOSE 1489 bool 1490 1491menu "Debug kernel data structures" 1492 1493config DEBUG_LIST 1494 bool "Debug linked list manipulation" 1495 depends on DEBUG_KERNEL || BUG_ON_DATA_CORRUPTION 1496 help 1497 Enable this to turn on extended checks in the linked-list 1498 walking routines. 1499 1500 If unsure, say N. 1501 1502config DEBUG_PLIST 1503 bool "Debug priority linked list manipulation" 1504 depends on DEBUG_KERNEL 1505 help 1506 Enable this to turn on extended checks in the priority-ordered 1507 linked-list (plist) walking routines. This checks the entire 1508 list multiple times during each manipulation. 1509 1510 If unsure, say N. 1511 1512config DEBUG_SG 1513 bool "Debug SG table operations" 1514 depends on DEBUG_KERNEL 1515 help 1516 Enable this to turn on checks on scatter-gather tables. This can 1517 help find problems with drivers that do not properly initialize 1518 their sg tables. 1519 1520 If unsure, say N. 1521 1522config DEBUG_NOTIFIERS 1523 bool "Debug notifier call chains" 1524 depends on DEBUG_KERNEL 1525 help 1526 Enable this to turn on sanity checking for notifier call chains. 1527 This is most useful for kernel developers to make sure that 1528 modules properly unregister themselves from notifier chains. 1529 This is a relatively cheap check but if you care about maximum 1530 performance, say N. 1531 1532config BUG_ON_DATA_CORRUPTION 1533 bool "Trigger a BUG when data corruption is detected" 1534 select DEBUG_LIST 1535 help 1536 Select this option if the kernel should BUG when it encounters 1537 data corruption in kernel memory structures when they get checked 1538 for validity. 1539 1540 If unsure, say N. 1541 1542endmenu 1543 1544config DEBUG_CREDENTIALS 1545 bool "Debug credential management" 1546 depends on DEBUG_KERNEL 1547 help 1548 Enable this to turn on some debug checking for credential 1549 management. The additional code keeps track of the number of 1550 pointers from task_structs to any given cred struct, and checks to 1551 see that this number never exceeds the usage count of the cred 1552 struct. 1553 1554 Furthermore, if SELinux is enabled, this also checks that the 1555 security pointer in the cred struct is never seen to be invalid. 1556 1557 If unsure, say N. 1558 1559source "kernel/rcu/Kconfig.debug" 1560 1561config DEBUG_WQ_FORCE_RR_CPU 1562 bool "Force round-robin CPU selection for unbound work items" 1563 depends on DEBUG_KERNEL 1564 default n 1565 help 1566 Workqueue used to implicitly guarantee that work items queued 1567 without explicit CPU specified are put on the local CPU. This 1568 guarantee is no longer true and while local CPU is still 1569 preferred work items may be put on foreign CPUs. Kernel 1570 parameter "workqueue.debug_force_rr_cpu" is added to force 1571 round-robin CPU selection to flush out usages which depend on the 1572 now broken guarantee. This config option enables the debug 1573 feature by default. When enabled, memory and cache locality will 1574 be impacted. 1575 1576config DEBUG_BLOCK_EXT_DEVT 1577 bool "Force extended block device numbers and spread them" 1578 depends on DEBUG_KERNEL 1579 depends on BLOCK 1580 default n 1581 help 1582 BIG FAT WARNING: ENABLING THIS OPTION MIGHT BREAK BOOTING ON 1583 SOME DISTRIBUTIONS. DO NOT ENABLE THIS UNLESS YOU KNOW WHAT 1584 YOU ARE DOING. Distros, please enable this and fix whatever 1585 is broken. 1586 1587 Conventionally, block device numbers are allocated from 1588 predetermined contiguous area. However, extended block area 1589 may introduce non-contiguous block device numbers. This 1590 option forces most block device numbers to be allocated from 1591 the extended space and spreads them to discover kernel or 1592 userland code paths which assume predetermined contiguous 1593 device number allocation. 1594 1595 Note that turning on this debug option shuffles all the 1596 device numbers for all IDE and SCSI devices including libata 1597 ones, so root partition specified using device number 1598 directly (via rdev or root=MAJ:MIN) won't work anymore. 1599 Textual device names (root=/dev/sdXn) will continue to work. 1600 1601 Say N if you are unsure. 1602 1603config CPU_HOTPLUG_STATE_CONTROL 1604 bool "Enable CPU hotplug state control" 1605 depends on DEBUG_KERNEL 1606 depends on HOTPLUG_CPU 1607 default n 1608 help 1609 Allows to write steps between "offline" and "online" to the CPUs 1610 sysfs target file so states can be stepped granular. This is a debug 1611 option for now as the hotplug machinery cannot be stopped and 1612 restarted at arbitrary points yet. 1613 1614 Say N if your are unsure. 1615 1616config LATENCYTOP 1617 bool "Latency measuring infrastructure" 1618 depends on DEBUG_KERNEL 1619 depends on STACKTRACE_SUPPORT 1620 depends on PROC_FS 1621 select FRAME_POINTER if !MIPS && !PPC && !S390 && !MICROBLAZE && !ARM && !ARC && !X86 1622 select KALLSYMS 1623 select KALLSYMS_ALL 1624 select STACKTRACE 1625 select SCHEDSTATS 1626 select SCHED_DEBUG 1627 help 1628 Enable this option if you want to use the LatencyTOP tool 1629 to find out which userspace is blocking on what kernel operations. 1630 1631source "kernel/trace/Kconfig" 1632 1633config PROVIDE_OHCI1394_DMA_INIT 1634 bool "Remote debugging over FireWire early on boot" 1635 depends on PCI && X86 1636 help 1637 If you want to debug problems which hang or crash the kernel early 1638 on boot and the crashing machine has a FireWire port, you can use 1639 this feature to remotely access the memory of the crashed machine 1640 over FireWire. This employs remote DMA as part of the OHCI1394 1641 specification which is now the standard for FireWire controllers. 1642 1643 With remote DMA, you can monitor the printk buffer remotely using 1644 firescope and access all memory below 4GB using fireproxy from gdb. 1645 Even controlling a kernel debugger is possible using remote DMA. 1646 1647 Usage: 1648 1649 If ohci1394_dma=early is used as boot parameter, it will initialize 1650 all OHCI1394 controllers which are found in the PCI config space. 1651 1652 As all changes to the FireWire bus such as enabling and disabling 1653 devices cause a bus reset and thereby disable remote DMA for all 1654 devices, be sure to have the cable plugged and FireWire enabled on 1655 the debugging host before booting the debug target for debugging. 1656 1657 This code (~1k) is freed after boot. By then, the firewire stack 1658 in charge of the OHCI-1394 controllers should be used instead. 1659 1660 See Documentation/core-api/debugging-via-ohci1394.rst for more information. 1661 1662source "samples/Kconfig" 1663 1664config ARCH_HAS_DEVMEM_IS_ALLOWED 1665 bool 1666 1667config STRICT_DEVMEM 1668 bool "Filter access to /dev/mem" 1669 depends on MMU && DEVMEM 1670 depends on ARCH_HAS_DEVMEM_IS_ALLOWED || GENERIC_LIB_DEVMEM_IS_ALLOWED 1671 default y if PPC || X86 || ARM64 1672 help 1673 If this option is disabled, you allow userspace (root) access to all 1674 of memory, including kernel and userspace memory. Accidental 1675 access to this is obviously disastrous, but specific access can 1676 be used by people debugging the kernel. Note that with PAT support 1677 enabled, even in this case there are restrictions on /dev/mem 1678 use due to the cache aliasing requirements. 1679 1680 If this option is switched on, and IO_STRICT_DEVMEM=n, the /dev/mem 1681 file only allows userspace access to PCI space and the BIOS code and 1682 data regions. This is sufficient for dosemu and X and all common 1683 users of /dev/mem. 1684 1685 If in doubt, say Y. 1686 1687config IO_STRICT_DEVMEM 1688 bool "Filter I/O access to /dev/mem" 1689 depends on STRICT_DEVMEM 1690 help 1691 If this option is disabled, you allow userspace (root) access to all 1692 io-memory regardless of whether a driver is actively using that 1693 range. Accidental access to this is obviously disastrous, but 1694 specific access can be used by people debugging kernel drivers. 1695 1696 If this option is switched on, the /dev/mem file only allows 1697 userspace access to *idle* io-memory ranges (see /proc/iomem) This 1698 may break traditional users of /dev/mem (dosemu, legacy X, etc...) 1699 if the driver using a given range cannot be disabled. 1700 1701 If in doubt, say Y. 1702 1703menu "$(SRCARCH) Debugging" 1704 1705source "arch/$(SRCARCH)/Kconfig.debug" 1706 1707endmenu 1708 1709menu "Kernel Testing and Coverage" 1710 1711source "lib/kunit/Kconfig" 1712 1713config NOTIFIER_ERROR_INJECTION 1714 tristate "Notifier error injection" 1715 depends on DEBUG_KERNEL 1716 select DEBUG_FS 1717 help 1718 This option provides the ability to inject artificial errors to 1719 specified notifier chain callbacks. It is useful to test the error 1720 handling of notifier call chain failures. 1721 1722 Say N if unsure. 1723 1724config PM_NOTIFIER_ERROR_INJECT 1725 tristate "PM notifier error injection module" 1726 depends on PM && NOTIFIER_ERROR_INJECTION 1727 default m if PM_DEBUG 1728 help 1729 This option provides the ability to inject artificial errors to 1730 PM notifier chain callbacks. It is controlled through debugfs 1731 interface /sys/kernel/debug/notifier-error-inject/pm 1732 1733 If the notifier call chain should be failed with some events 1734 notified, write the error code to "actions/<notifier event>/error". 1735 1736 Example: Inject PM suspend error (-12 = -ENOMEM) 1737 1738 # cd /sys/kernel/debug/notifier-error-inject/pm/ 1739 # echo -12 > actions/PM_SUSPEND_PREPARE/error 1740 # echo mem > /sys/power/state 1741 bash: echo: write error: Cannot allocate memory 1742 1743 To compile this code as a module, choose M here: the module will 1744 be called pm-notifier-error-inject. 1745 1746 If unsure, say N. 1747 1748config OF_RECONFIG_NOTIFIER_ERROR_INJECT 1749 tristate "OF reconfig notifier error injection module" 1750 depends on OF_DYNAMIC && NOTIFIER_ERROR_INJECTION 1751 help 1752 This option provides the ability to inject artificial errors to 1753 OF reconfig notifier chain callbacks. It is controlled 1754 through debugfs interface under 1755 /sys/kernel/debug/notifier-error-inject/OF-reconfig/ 1756 1757 If the notifier call chain should be failed with some events 1758 notified, write the error code to "actions/<notifier event>/error". 1759 1760 To compile this code as a module, choose M here: the module will 1761 be called of-reconfig-notifier-error-inject. 1762 1763 If unsure, say N. 1764 1765config NETDEV_NOTIFIER_ERROR_INJECT 1766 tristate "Netdev notifier error injection module" 1767 depends on NET && NOTIFIER_ERROR_INJECTION 1768 help 1769 This option provides the ability to inject artificial errors to 1770 netdevice notifier chain callbacks. It is controlled through debugfs 1771 interface /sys/kernel/debug/notifier-error-inject/netdev 1772 1773 If the notifier call chain should be failed with some events 1774 notified, write the error code to "actions/<notifier event>/error". 1775 1776 Example: Inject netdevice mtu change error (-22 = -EINVAL) 1777 1778 # cd /sys/kernel/debug/notifier-error-inject/netdev 1779 # echo -22 > actions/NETDEV_CHANGEMTU/error 1780 # ip link set eth0 mtu 1024 1781 RTNETLINK answers: Invalid argument 1782 1783 To compile this code as a module, choose M here: the module will 1784 be called netdev-notifier-error-inject. 1785 1786 If unsure, say N. 1787 1788config FUNCTION_ERROR_INJECTION 1789 def_bool y 1790 depends on HAVE_FUNCTION_ERROR_INJECTION && KPROBES 1791 1792config FAULT_INJECTION 1793 bool "Fault-injection framework" 1794 depends on DEBUG_KERNEL 1795 help 1796 Provide fault-injection framework. 1797 For more details, see Documentation/fault-injection/. 1798 1799config FAILSLAB 1800 bool "Fault-injection capability for kmalloc" 1801 depends on FAULT_INJECTION 1802 depends on SLAB || SLUB 1803 help 1804 Provide fault-injection capability for kmalloc. 1805 1806config FAIL_PAGE_ALLOC 1807 bool "Fault-injection capability for alloc_pages()" 1808 depends on FAULT_INJECTION 1809 help 1810 Provide fault-injection capability for alloc_pages(). 1811 1812config FAULT_INJECTION_USERCOPY 1813 bool "Fault injection capability for usercopy functions" 1814 depends on FAULT_INJECTION 1815 help 1816 Provides fault-injection capability to inject failures 1817 in usercopy functions (copy_from_user(), get_user(), ...). 1818 1819config FAIL_MAKE_REQUEST 1820 bool "Fault-injection capability for disk IO" 1821 depends on FAULT_INJECTION && BLOCK 1822 help 1823 Provide fault-injection capability for disk IO. 1824 1825config FAIL_IO_TIMEOUT 1826 bool "Fault-injection capability for faking disk interrupts" 1827 depends on FAULT_INJECTION && BLOCK 1828 help 1829 Provide fault-injection capability on end IO handling. This 1830 will make the block layer "forget" an interrupt as configured, 1831 thus exercising the error handling. 1832 1833 Only works with drivers that use the generic timeout handling, 1834 for others it wont do anything. 1835 1836config FAIL_FUTEX 1837 bool "Fault-injection capability for futexes" 1838 select DEBUG_FS 1839 depends on FAULT_INJECTION && FUTEX 1840 help 1841 Provide fault-injection capability for futexes. 1842 1843config FAULT_INJECTION_DEBUG_FS 1844 bool "Debugfs entries for fault-injection capabilities" 1845 depends on FAULT_INJECTION && SYSFS && DEBUG_FS 1846 help 1847 Enable configuration of fault-injection capabilities via debugfs. 1848 1849config FAIL_FUNCTION 1850 bool "Fault-injection capability for functions" 1851 depends on FAULT_INJECTION_DEBUG_FS && FUNCTION_ERROR_INJECTION 1852 help 1853 Provide function-based fault-injection capability. 1854 This will allow you to override a specific function with a return 1855 with given return value. As a result, function caller will see 1856 an error value and have to handle it. This is useful to test the 1857 error handling in various subsystems. 1858 1859config FAIL_MMC_REQUEST 1860 bool "Fault-injection capability for MMC IO" 1861 depends on FAULT_INJECTION_DEBUG_FS && MMC 1862 help 1863 Provide fault-injection capability for MMC IO. 1864 This will make the mmc core return data errors. This is 1865 useful to test the error handling in the mmc block device 1866 and to test how the mmc host driver handles retries from 1867 the block device. 1868 1869config FAULT_INJECTION_STACKTRACE_FILTER 1870 bool "stacktrace filter for fault-injection capabilities" 1871 depends on FAULT_INJECTION_DEBUG_FS && STACKTRACE_SUPPORT 1872 depends on !X86_64 1873 select STACKTRACE 1874 select FRAME_POINTER if !MIPS && !PPC && !S390 && !MICROBLAZE && !ARM && !ARC && !X86 1875 help 1876 Provide stacktrace filter for fault-injection capabilities 1877 1878config ARCH_HAS_KCOV 1879 bool 1880 help 1881 An architecture should select this when it can successfully 1882 build and run with CONFIG_KCOV. This typically requires 1883 disabling instrumentation for some early boot code. 1884 1885config CC_HAS_SANCOV_TRACE_PC 1886 def_bool $(cc-option,-fsanitize-coverage=trace-pc) 1887 1888 1889config KCOV 1890 bool "Code coverage for fuzzing" 1891 depends on ARCH_HAS_KCOV 1892 depends on CC_HAS_SANCOV_TRACE_PC || GCC_PLUGINS 1893 select DEBUG_FS 1894 select GCC_PLUGIN_SANCOV if !CC_HAS_SANCOV_TRACE_PC 1895 help 1896 KCOV exposes kernel code coverage information in a form suitable 1897 for coverage-guided fuzzing (randomized testing). 1898 1899 If RANDOMIZE_BASE is enabled, PC values will not be stable across 1900 different machines and across reboots. If you need stable PC values, 1901 disable RANDOMIZE_BASE. 1902 1903 For more details, see Documentation/dev-tools/kcov.rst. 1904 1905config KCOV_ENABLE_COMPARISONS 1906 bool "Enable comparison operands collection by KCOV" 1907 depends on KCOV 1908 depends on $(cc-option,-fsanitize-coverage=trace-cmp) 1909 help 1910 KCOV also exposes operands of every comparison in the instrumented 1911 code along with operand sizes and PCs of the comparison instructions. 1912 These operands can be used by fuzzing engines to improve the quality 1913 of fuzzing coverage. 1914 1915config KCOV_INSTRUMENT_ALL 1916 bool "Instrument all code by default" 1917 depends on KCOV 1918 default y 1919 help 1920 If you are doing generic system call fuzzing (like e.g. syzkaller), 1921 then you will want to instrument the whole kernel and you should 1922 say y here. If you are doing more targeted fuzzing (like e.g. 1923 filesystem fuzzing with AFL) then you will want to enable coverage 1924 for more specific subsets of files, and should say n here. 1925 1926config KCOV_IRQ_AREA_SIZE 1927 hex "Size of interrupt coverage collection area in words" 1928 depends on KCOV 1929 default 0x40000 1930 help 1931 KCOV uses preallocated per-cpu areas to collect coverage from 1932 soft interrupts. This specifies the size of those areas in the 1933 number of unsigned long words. 1934 1935menuconfig RUNTIME_TESTING_MENU 1936 bool "Runtime Testing" 1937 def_bool y 1938 1939if RUNTIME_TESTING_MENU 1940 1941config LKDTM 1942 tristate "Linux Kernel Dump Test Tool Module" 1943 depends on DEBUG_FS 1944 help 1945 This module enables testing of the different dumping mechanisms by 1946 inducing system failures at predefined crash points. 1947 If you don't need it: say N 1948 Choose M here to compile this code as a module. The module will be 1949 called lkdtm. 1950 1951 Documentation on how to use the module can be found in 1952 Documentation/fault-injection/provoke-crashes.rst 1953 1954config TEST_LIST_SORT 1955 tristate "Linked list sorting test" 1956 depends on DEBUG_KERNEL || m 1957 help 1958 Enable this to turn on 'list_sort()' function test. This test is 1959 executed only once during system boot (so affects only boot time), 1960 or at module load time. 1961 1962 If unsure, say N. 1963 1964config TEST_MIN_HEAP 1965 tristate "Min heap test" 1966 depends on DEBUG_KERNEL || m 1967 help 1968 Enable this to turn on min heap function tests. This test is 1969 executed only once during system boot (so affects only boot time), 1970 or at module load time. 1971 1972 If unsure, say N. 1973 1974config TEST_SORT 1975 tristate "Array-based sort test" 1976 depends on DEBUG_KERNEL || m 1977 help 1978 This option enables the self-test function of 'sort()' at boot, 1979 or at module load time. 1980 1981 If unsure, say N. 1982 1983config KPROBES_SANITY_TEST 1984 bool "Kprobes sanity tests" 1985 depends on DEBUG_KERNEL 1986 depends on KPROBES 1987 help 1988 This option provides for testing basic kprobes functionality on 1989 boot. Samples of kprobe and kretprobe are inserted and 1990 verified for functionality. 1991 1992 Say N if you are unsure. 1993 1994config BACKTRACE_SELF_TEST 1995 tristate "Self test for the backtrace code" 1996 depends on DEBUG_KERNEL 1997 help 1998 This option provides a kernel module that can be used to test 1999 the kernel stack backtrace code. This option is not useful 2000 for distributions or general kernels, but only for kernel 2001 developers working on architecture code. 2002 2003 Note that if you want to also test saved backtraces, you will 2004 have to enable STACKTRACE as well. 2005 2006 Say N if you are unsure. 2007 2008config RBTREE_TEST 2009 tristate "Red-Black tree test" 2010 depends on DEBUG_KERNEL 2011 help 2012 A benchmark measuring the performance of the rbtree library. 2013 Also includes rbtree invariant checks. 2014 2015config REED_SOLOMON_TEST 2016 tristate "Reed-Solomon library test" 2017 depends on DEBUG_KERNEL || m 2018 select REED_SOLOMON 2019 select REED_SOLOMON_ENC16 2020 select REED_SOLOMON_DEC16 2021 help 2022 This option enables the self-test function of rslib at boot, 2023 or at module load time. 2024 2025 If unsure, say N. 2026 2027config INTERVAL_TREE_TEST 2028 tristate "Interval tree test" 2029 depends on DEBUG_KERNEL 2030 select INTERVAL_TREE 2031 help 2032 A benchmark measuring the performance of the interval tree library 2033 2034config PERCPU_TEST 2035 tristate "Per cpu operations test" 2036 depends on m && DEBUG_KERNEL 2037 help 2038 Enable this option to build test module which validates per-cpu 2039 operations. 2040 2041 If unsure, say N. 2042 2043config ATOMIC64_SELFTEST 2044 tristate "Perform an atomic64_t self-test" 2045 help 2046 Enable this option to test the atomic64_t functions at boot or 2047 at module load time. 2048 2049 If unsure, say N. 2050 2051config ASYNC_RAID6_TEST 2052 tristate "Self test for hardware accelerated raid6 recovery" 2053 depends on ASYNC_RAID6_RECOV 2054 select ASYNC_MEMCPY 2055 help 2056 This is a one-shot self test that permutes through the 2057 recovery of all the possible two disk failure scenarios for a 2058 N-disk array. Recovery is performed with the asynchronous 2059 raid6 recovery routines, and will optionally use an offload 2060 engine if one is available. 2061 2062 If unsure, say N. 2063 2064config TEST_HEXDUMP 2065 tristate "Test functions located in the hexdump module at runtime" 2066 2067config TEST_STRING_HELPERS 2068 tristate "Test functions located in the string_helpers module at runtime" 2069 2070config TEST_STRSCPY 2071 tristate "Test strscpy*() family of functions at runtime" 2072 2073config TEST_KSTRTOX 2074 tristate "Test kstrto*() family of functions at runtime" 2075 2076config TEST_PRINTF 2077 tristate "Test printf() family of functions at runtime" 2078 2079config TEST_BITMAP 2080 tristate "Test bitmap_*() family of functions at runtime" 2081 help 2082 Enable this option to test the bitmap functions at boot. 2083 2084 If unsure, say N. 2085 2086config TEST_UUID 2087 tristate "Test functions located in the uuid module at runtime" 2088 2089config TEST_XARRAY 2090 tristate "Test the XArray code at runtime" 2091 2092config TEST_OVERFLOW 2093 tristate "Test check_*_overflow() functions at runtime" 2094 2095config TEST_RHASHTABLE 2096 tristate "Perform selftest on resizable hash table" 2097 help 2098 Enable this option to test the rhashtable functions at boot. 2099 2100 If unsure, say N. 2101 2102config TEST_HASH 2103 tristate "Perform selftest on hash functions" 2104 help 2105 Enable this option to test the kernel's integer (<linux/hash.h>), 2106 string (<linux/stringhash.h>), and siphash (<linux/siphash.h>) 2107 hash functions on boot (or module load). 2108 2109 This is intended to help people writing architecture-specific 2110 optimized versions. If unsure, say N. 2111 2112config TEST_IDA 2113 tristate "Perform selftest on IDA functions" 2114 2115config TEST_PARMAN 2116 tristate "Perform selftest on priority array manager" 2117 depends on PARMAN 2118 help 2119 Enable this option to test priority array manager on boot 2120 (or module load). 2121 2122 If unsure, say N. 2123 2124config TEST_IRQ_TIMINGS 2125 bool "IRQ timings selftest" 2126 depends on IRQ_TIMINGS 2127 help 2128 Enable this option to test the irq timings code on boot. 2129 2130 If unsure, say N. 2131 2132config TEST_LKM 2133 tristate "Test module loading with 'hello world' module" 2134 depends on m 2135 help 2136 This builds the "test_module" module that emits "Hello, world" 2137 on printk when loaded. It is designed to be used for basic 2138 evaluation of the module loading subsystem (for example when 2139 validating module verification). It lacks any extra dependencies, 2140 and will not normally be loaded by the system unless explicitly 2141 requested by name. 2142 2143 If unsure, say N. 2144 2145config TEST_BITOPS 2146 tristate "Test module for compilation of bitops operations" 2147 depends on m 2148 help 2149 This builds the "test_bitops" module that is much like the 2150 TEST_LKM module except that it does a basic exercise of the 2151 set/clear_bit macros and get_count_order/long to make sure there are 2152 no compiler warnings from C=1 sparse checker or -Wextra 2153 compilations. It has no dependencies and doesn't run or load unless 2154 explicitly requested by name. for example: modprobe test_bitops. 2155 2156 If unsure, say N. 2157 2158config TEST_VMALLOC 2159 tristate "Test module for stress/performance analysis of vmalloc allocator" 2160 default n 2161 depends on MMU 2162 depends on m 2163 help 2164 This builds the "test_vmalloc" module that should be used for 2165 stress and performance analysis. So, any new change for vmalloc 2166 subsystem can be evaluated from performance and stability point 2167 of view. 2168 2169 If unsure, say N. 2170 2171config TEST_USER_COPY 2172 tristate "Test user/kernel boundary protections" 2173 depends on m 2174 help 2175 This builds the "test_user_copy" module that runs sanity checks 2176 on the copy_to/from_user infrastructure, making sure basic 2177 user/kernel boundary testing is working. If it fails to load, 2178 a regression has been detected in the user/kernel memory boundary 2179 protections. 2180 2181 If unsure, say N. 2182 2183config TEST_BPF 2184 tristate "Test BPF filter functionality" 2185 depends on m && NET 2186 help 2187 This builds the "test_bpf" module that runs various test vectors 2188 against the BPF interpreter or BPF JIT compiler depending on the 2189 current setting. This is in particular useful for BPF JIT compiler 2190 development, but also to run regression tests against changes in 2191 the interpreter code. It also enables test stubs for eBPF maps and 2192 verifier used by user space verifier testsuite. 2193 2194 If unsure, say N. 2195 2196config TEST_BLACKHOLE_DEV 2197 tristate "Test blackhole netdev functionality" 2198 depends on m && NET 2199 help 2200 This builds the "test_blackhole_dev" module that validates the 2201 data path through this blackhole netdev. 2202 2203 If unsure, say N. 2204 2205config FIND_BIT_BENCHMARK 2206 tristate "Test find_bit functions" 2207 help 2208 This builds the "test_find_bit" module that measure find_*_bit() 2209 functions performance. 2210 2211 If unsure, say N. 2212 2213config TEST_FIRMWARE 2214 tristate "Test firmware loading via userspace interface" 2215 depends on FW_LOADER 2216 help 2217 This builds the "test_firmware" module that creates a userspace 2218 interface for testing firmware loading. This can be used to 2219 control the triggering of firmware loading without needing an 2220 actual firmware-using device. The contents can be rechecked by 2221 userspace. 2222 2223 If unsure, say N. 2224 2225config TEST_SYSCTL 2226 tristate "sysctl test driver" 2227 depends on PROC_SYSCTL 2228 help 2229 This builds the "test_sysctl" module. This driver enables to test the 2230 proc sysctl interfaces available to drivers safely without affecting 2231 production knobs which might alter system functionality. 2232 2233 If unsure, say N. 2234 2235config BITFIELD_KUNIT 2236 tristate "KUnit test bitfield functions at runtime" 2237 depends on KUNIT 2238 help 2239 Enable this option to test the bitfield functions at boot. 2240 2241 KUnit tests run during boot and output the results to the debug log 2242 in TAP format (http://testanything.org/). Only useful for kernel devs 2243 running the KUnit test harness, and not intended for inclusion into a 2244 production build. 2245 2246 For more information on KUnit and unit tests in general please refer 2247 to the KUnit documentation in Documentation/dev-tools/kunit/. 2248 2249 If unsure, say N. 2250 2251config RESOURCE_KUNIT_TEST 2252 tristate "KUnit test for resource API" 2253 depends on KUNIT 2254 help 2255 This builds the resource API unit test. 2256 Tests the logic of API provided by resource.c and ioport.h. 2257 For more information on KUnit and unit tests in general please refer 2258 to the KUnit documentation in Documentation/dev-tools/kunit/. 2259 2260 If unsure, say N. 2261 2262config SYSCTL_KUNIT_TEST 2263 tristate "KUnit test for sysctl" if !KUNIT_ALL_TESTS 2264 depends on KUNIT 2265 default KUNIT_ALL_TESTS 2266 help 2267 This builds the proc sysctl unit test, which runs on boot. 2268 Tests the API contract and implementation correctness of sysctl. 2269 For more information on KUnit and unit tests in general please refer 2270 to the KUnit documentation in Documentation/dev-tools/kunit/. 2271 2272 If unsure, say N. 2273 2274config LIST_KUNIT_TEST 2275 tristate "KUnit Test for Kernel Linked-list structures" if !KUNIT_ALL_TESTS 2276 depends on KUNIT 2277 default KUNIT_ALL_TESTS 2278 help 2279 This builds the linked list KUnit test suite. 2280 It tests that the API and basic functionality of the list_head type 2281 and associated macros. 2282 2283 KUnit tests run during boot and output the results to the debug log 2284 in TAP format (https://testanything.org/). Only useful for kernel devs 2285 running the KUnit test harness, and not intended for inclusion into a 2286 production build. 2287 2288 For more information on KUnit and unit tests in general please refer 2289 to the KUnit documentation in Documentation/dev-tools/kunit/. 2290 2291 If unsure, say N. 2292 2293config LINEAR_RANGES_TEST 2294 tristate "KUnit test for linear_ranges" 2295 depends on KUNIT 2296 select LINEAR_RANGES 2297 help 2298 This builds the linear_ranges unit test, which runs on boot. 2299 Tests the linear_ranges logic correctness. 2300 For more information on KUnit and unit tests in general please refer 2301 to the KUnit documentation in Documentation/dev-tools/kunit/. 2302 2303 If unsure, say N. 2304 2305config CMDLINE_KUNIT_TEST 2306 tristate "KUnit test for cmdline API" 2307 depends on KUNIT 2308 help 2309 This builds the cmdline API unit test. 2310 Tests the logic of API provided by cmdline.c. 2311 For more information on KUnit and unit tests in general please refer 2312 to the KUnit documentation in Documentation/dev-tools/kunit/. 2313 2314 If unsure, say N. 2315 2316config BITS_TEST 2317 tristate "KUnit test for bits.h" 2318 depends on KUNIT 2319 help 2320 This builds the bits unit test. 2321 Tests the logic of macros defined in bits.h. 2322 For more information on KUnit and unit tests in general please refer 2323 to the KUnit documentation in Documentation/dev-tools/kunit/. 2324 2325 If unsure, say N. 2326 2327config TEST_UDELAY 2328 tristate "udelay test driver" 2329 help 2330 This builds the "udelay_test" module that helps to make sure 2331 that udelay() is working properly. 2332 2333 If unsure, say N. 2334 2335config TEST_STATIC_KEYS 2336 tristate "Test static keys" 2337 depends on m 2338 help 2339 Test the static key interfaces. 2340 2341 If unsure, say N. 2342 2343config TEST_KMOD 2344 tristate "kmod stress tester" 2345 depends on m 2346 depends on NETDEVICES && NET_CORE && INET # for TUN 2347 depends on BLOCK 2348 select TEST_LKM 2349 select XFS_FS 2350 select TUN 2351 select BTRFS_FS 2352 help 2353 Test the kernel's module loading mechanism: kmod. kmod implements 2354 support to load modules using the Linux kernel's usermode helper. 2355 This test provides a series of tests against kmod. 2356 2357 Although technically you can either build test_kmod as a module or 2358 into the kernel we disallow building it into the kernel since 2359 it stress tests request_module() and this will very likely cause 2360 some issues by taking over precious threads available from other 2361 module load requests, ultimately this could be fatal. 2362 2363 To run tests run: 2364 2365 tools/testing/selftests/kmod/kmod.sh --help 2366 2367 If unsure, say N. 2368 2369config TEST_DEBUG_VIRTUAL 2370 tristate "Test CONFIG_DEBUG_VIRTUAL feature" 2371 depends on DEBUG_VIRTUAL 2372 help 2373 Test the kernel's ability to detect incorrect calls to 2374 virt_to_phys() done against the non-linear part of the 2375 kernel's virtual address map. 2376 2377 If unsure, say N. 2378 2379config TEST_MEMCAT_P 2380 tristate "Test memcat_p() helper function" 2381 help 2382 Test the memcat_p() helper for correctly merging two 2383 pointer arrays together. 2384 2385 If unsure, say N. 2386 2387config TEST_LIVEPATCH 2388 tristate "Test livepatching" 2389 default n 2390 depends on DYNAMIC_DEBUG 2391 depends on LIVEPATCH 2392 depends on m 2393 help 2394 Test kernel livepatching features for correctness. The tests will 2395 load test modules that will be livepatched in various scenarios. 2396 2397 To run all the livepatching tests: 2398 2399 make -C tools/testing/selftests TARGETS=livepatch run_tests 2400 2401 Alternatively, individual tests may be invoked: 2402 2403 tools/testing/selftests/livepatch/test-callbacks.sh 2404 tools/testing/selftests/livepatch/test-livepatch.sh 2405 tools/testing/selftests/livepatch/test-shadow-vars.sh 2406 2407 If unsure, say N. 2408 2409config TEST_OBJAGG 2410 tristate "Perform selftest on object aggreration manager" 2411 default n 2412 depends on OBJAGG 2413 help 2414 Enable this option to test object aggregation manager on boot 2415 (or module load). 2416 2417 2418config TEST_STACKINIT 2419 tristate "Test level of stack variable initialization" 2420 help 2421 Test if the kernel is zero-initializing stack variables and 2422 padding. Coverage is controlled by compiler flags, 2423 CONFIG_GCC_PLUGIN_STRUCTLEAK, CONFIG_GCC_PLUGIN_STRUCTLEAK_BYREF, 2424 or CONFIG_GCC_PLUGIN_STRUCTLEAK_BYREF_ALL. 2425 2426 If unsure, say N. 2427 2428config TEST_MEMINIT 2429 tristate "Test heap/page initialization" 2430 help 2431 Test if the kernel is zero-initializing heap and page allocations. 2432 This can be useful to test init_on_alloc and init_on_free features. 2433 2434 If unsure, say N. 2435 2436config TEST_HMM 2437 tristate "Test HMM (Heterogeneous Memory Management)" 2438 depends on TRANSPARENT_HUGEPAGE 2439 depends on DEVICE_PRIVATE 2440 select HMM_MIRROR 2441 select MMU_NOTIFIER 2442 help 2443 This is a pseudo device driver solely for testing HMM. 2444 Say M here if you want to build the HMM test module. 2445 Doing so will allow you to run tools/testing/selftest/vm/hmm-tests. 2446 2447 If unsure, say N. 2448 2449config TEST_FREE_PAGES 2450 tristate "Test freeing pages" 2451 help 2452 Test that a memory leak does not occur due to a race between 2453 freeing a block of pages and a speculative page reference. 2454 Loading this module is safe if your kernel has the bug fixed. 2455 If the bug is not fixed, it will leak gigabytes of memory and 2456 probably OOM your system. 2457 2458config TEST_FPU 2459 tristate "Test floating point operations in kernel space" 2460 depends on X86 && !KCOV_INSTRUMENT_ALL 2461 help 2462 Enable this option to add /sys/kernel/debug/selftest_helpers/test_fpu 2463 which will trigger a sequence of floating point operations. This is used 2464 for self-testing floating point control register setting in 2465 kernel_fpu_begin(). 2466 2467 If unsure, say N. 2468 2469endif # RUNTIME_TESTING_MENU 2470 2471config MEMTEST 2472 bool "Memtest" 2473 help 2474 This option adds a kernel parameter 'memtest', which allows memtest 2475 to be set. 2476 memtest=0, mean disabled; -- default 2477 memtest=1, mean do 1 test pattern; 2478 ... 2479 memtest=17, mean do 17 test patterns. 2480 If you are unsure how to answer this question, answer N. 2481 2482 2483 2484config HYPERV_TESTING 2485 bool "Microsoft Hyper-V driver testing" 2486 default n 2487 depends on HYPERV && DEBUG_FS 2488 help 2489 Select this option to enable Hyper-V vmbus testing. 2490 2491endmenu # "Kernel Testing and Coverage" 2492 2493source "Documentation/Kconfig" 2494 2495endmenu # Kernel hacking 2496