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 259choice 260 prompt "DWARF version" 261 help 262 Which version of DWARF debug info to emit. 263 264config DEBUG_INFO_DWARF_TOOLCHAIN_DEFAULT 265 bool "Rely on the toolchain's implicit default DWARF version" 266 help 267 The implicit default version of DWARF debug info produced by a 268 toolchain changes over time. 269 270 This can break consumers of the debug info that haven't upgraded to 271 support newer revisions, and prevent testing newer versions, but 272 those should be less common scenarios. 273 274 If unsure, say Y. 275 276config DEBUG_INFO_DWARF4 277 bool "Generate DWARF Version 4 debuginfo" 278 help 279 Generate DWARF v4 debug info. This requires gcc 4.5+ and gdb 7.0+. 280 281 If you have consumers of DWARF debug info that are not ready for 282 newer revisions of DWARF, you may wish to choose this or have your 283 config select this. 284 285config DEBUG_INFO_DWARF5 286 bool "Generate DWARF Version 5 debuginfo" 287 depends on GCC_VERSION >= 50000 || CC_IS_CLANG 288 depends on CC_IS_GCC || $(success,$(srctree)/scripts/test_dwarf5_support.sh $(CC) $(CLANG_FLAGS)) 289 depends on !DEBUG_INFO_BTF 290 help 291 Generate DWARF v5 debug info. Requires binutils 2.35.2, gcc 5.0+ (gcc 292 5.0+ accepts the -gdwarf-5 flag but only had partial support for some 293 draft features until 7.0), and gdb 8.0+. 294 295 Changes to the structure of debug info in Version 5 allow for around 296 15-18% savings in resulting image and debug info section sizes as 297 compared to DWARF Version 4. DWARF Version 5 standardizes previous 298 extensions such as accelerators for symbol indexing and the format 299 for fission (.dwo/.dwp) files. Users may not want to select this 300 config if they rely on tooling that has not yet been updated to 301 support DWARF Version 5. 302 303endchoice # "DWARF version" 304 305config DEBUG_INFO_BTF 306 bool "Generate BTF typeinfo" 307 depends on !DEBUG_INFO_SPLIT && !DEBUG_INFO_REDUCED 308 depends on !GCC_PLUGIN_RANDSTRUCT || COMPILE_TEST 309 help 310 Generate deduplicated BTF type information from DWARF debug info. 311 Turning this on expects presence of pahole tool, which will convert 312 DWARF type info into equivalent deduplicated BTF type info. 313 314config PAHOLE_HAS_SPLIT_BTF 315 def_bool $(success, test `$(PAHOLE) --version | sed -E 's/v([0-9]+)\.([0-9]+)/\1\2/'` -ge "119") 316 317config DEBUG_INFO_BTF_MODULES 318 def_bool y 319 depends on DEBUG_INFO_BTF && MODULES && PAHOLE_HAS_SPLIT_BTF 320 help 321 Generate compact split BTF type information for kernel modules. 322 323config GDB_SCRIPTS 324 bool "Provide GDB scripts for kernel debugging" 325 help 326 This creates the required links to GDB helper scripts in the 327 build directory. If you load vmlinux into gdb, the helper 328 scripts will be automatically imported by gdb as well, and 329 additional functions are available to analyze a Linux kernel 330 instance. See Documentation/dev-tools/gdb-kernel-debugging.rst 331 for further details. 332 333endif # DEBUG_INFO 334 335config FRAME_WARN 336 int "Warn for stack frames larger than" 337 range 0 8192 338 default 2048 if GCC_PLUGIN_LATENT_ENTROPY 339 default 1280 if (!64BIT && PARISC) 340 default 1024 if (!64BIT && !PARISC) 341 default 2048 if 64BIT 342 help 343 Tell gcc to warn at build time for stack frames larger than this. 344 Setting this too low will cause a lot of warnings. 345 Setting it to 0 disables the warning. 346 347config STRIP_ASM_SYMS 348 bool "Strip assembler-generated symbols during link" 349 default n 350 help 351 Strip internal assembler-generated symbols during a link (symbols 352 that look like '.Lxxx') so they don't pollute the output of 353 get_wchan() and suchlike. 354 355config READABLE_ASM 356 bool "Generate readable assembler code" 357 depends on DEBUG_KERNEL 358 help 359 Disable some compiler optimizations that tend to generate human unreadable 360 assembler output. This may make the kernel slightly slower, but it helps 361 to keep kernel developers who have to stare a lot at assembler listings 362 sane. 363 364config HEADERS_INSTALL 365 bool "Install uapi headers to usr/include" 366 depends on !UML 367 help 368 This option will install uapi headers (headers exported to user-space) 369 into the usr/include directory for use during the kernel build. 370 This is unneeded for building the kernel itself, but needed for some 371 user-space program samples. It is also needed by some features such 372 as uapi header sanity checks. 373 374config DEBUG_SECTION_MISMATCH 375 bool "Enable full Section mismatch analysis" 376 help 377 The section mismatch analysis checks if there are illegal 378 references from one section to another section. 379 During linktime or runtime, some sections are dropped; 380 any use of code/data previously in these sections would 381 most likely result in an oops. 382 In the code, functions and variables are annotated with 383 __init,, etc. (see the full list in include/linux/init.h), 384 which results in the code/data being placed in specific sections. 385 The section mismatch analysis is always performed after a full 386 kernel build, and enabling this option causes the following 387 additional step to occur: 388 - Add the option -fno-inline-functions-called-once to gcc commands. 389 When inlining a function annotated with __init in a non-init 390 function, we would lose the section information and thus 391 the analysis would not catch the illegal reference. 392 This option tells gcc to inline less (but it does result in 393 a larger kernel). 394 395config SECTION_MISMATCH_WARN_ONLY 396 bool "Make section mismatch errors non-fatal" 397 default y 398 help 399 If you say N here, the build process will fail if there are any 400 section mismatch, instead of just throwing warnings. 401 402 If unsure, say Y. 403 404config DEBUG_FORCE_FUNCTION_ALIGN_32B 405 bool "Force all function address 32B aligned" if EXPERT 406 help 407 There are cases that a commit from one domain changes the function 408 address alignment of other domains, and cause magic performance 409 bump (regression or improvement). Enable this option will help to 410 verify if the bump is caused by function alignment changes, while 411 it will slightly increase the kernel size and affect icache usage. 412 413 It is mainly for debug and performance tuning use. 414 415# 416# Select this config option from the architecture Kconfig, if it 417# is preferred to always offer frame pointers as a config 418# option on the architecture (regardless of KERNEL_DEBUG): 419# 420config ARCH_WANT_FRAME_POINTERS 421 bool 422 423config FRAME_POINTER 424 bool "Compile the kernel with frame pointers" 425 depends on DEBUG_KERNEL && (M68K || UML || SUPERH) || ARCH_WANT_FRAME_POINTERS 426 default y if (DEBUG_INFO && UML) || ARCH_WANT_FRAME_POINTERS 427 help 428 If you say Y here the resulting kernel image will be slightly 429 larger and slower, but it gives very useful debugging information 430 in case of kernel bugs. (precise oopses/stacktraces/warnings) 431 432config STACK_VALIDATION 433 bool "Compile-time stack metadata validation" 434 depends on HAVE_STACK_VALIDATION 435 default n 436 help 437 Add compile-time checks to validate stack metadata, including frame 438 pointers (if CONFIG_FRAME_POINTER is enabled). This helps ensure 439 that runtime stack traces are more reliable. 440 441 This is also a prerequisite for generation of ORC unwind data, which 442 is needed for CONFIG_UNWINDER_ORC. 443 444 For more information, see 445 tools/objtool/Documentation/stack-validation.txt. 446 447config VMLINUX_VALIDATION 448 bool 449 depends on STACK_VALIDATION && DEBUG_ENTRY && !PARAVIRT 450 default y 451 452config DEBUG_FORCE_WEAK_PER_CPU 453 bool "Force weak per-cpu definitions" 454 depends on DEBUG_KERNEL 455 help 456 s390 and alpha require percpu variables in modules to be 457 defined weak to work around addressing range issue which 458 puts the following two restrictions on percpu variable 459 definitions. 460 461 1. percpu symbols must be unique whether static or not 462 2. percpu variables can't be defined inside a function 463 464 To ensure that generic code follows the above rules, this 465 option forces all percpu variables to be defined as weak. 466 467endmenu # "Compiler options" 468 469menu "Generic Kernel Debugging Instruments" 470 471config MAGIC_SYSRQ 472 bool "Magic SysRq key" 473 depends on !UML 474 help 475 If you say Y here, you will have some control over the system even 476 if the system crashes for example during kernel debugging (e.g., you 477 will be able to flush the buffer cache to disk, reboot the system 478 immediately or dump some status information). This is accomplished 479 by pressing various keys while holding SysRq (Alt+PrintScreen). It 480 also works on a serial console (on PC hardware at least), if you 481 send a BREAK and then within 5 seconds a command keypress. The 482 keys are documented in <file:Documentation/admin-guide/sysrq.rst>. 483 Don't say Y unless you really know what this hack does. 484 485config MAGIC_SYSRQ_DEFAULT_ENABLE 486 hex "Enable magic SysRq key functions by default" 487 depends on MAGIC_SYSRQ 488 default 0x1 489 help 490 Specifies which SysRq key functions are enabled by default. 491 This may be set to 1 or 0 to enable or disable them all, or 492 to a bitmask as described in Documentation/admin-guide/sysrq.rst. 493 494config MAGIC_SYSRQ_SERIAL 495 bool "Enable magic SysRq key over serial" 496 depends on MAGIC_SYSRQ 497 default y 498 help 499 Many embedded boards have a disconnected TTL level serial which can 500 generate some garbage that can lead to spurious false sysrq detects. 501 This option allows you to decide whether you want to enable the 502 magic SysRq key. 503 504config MAGIC_SYSRQ_SERIAL_SEQUENCE 505 string "Char sequence that enables magic SysRq over serial" 506 depends on MAGIC_SYSRQ_SERIAL 507 default "" 508 help 509 Specifies a sequence of characters that can follow BREAK to enable 510 SysRq on a serial console. 511 512 If unsure, leave an empty string and the option will not be enabled. 513 514config DEBUG_FS 515 bool "Debug Filesystem" 516 help 517 debugfs is a virtual file system that kernel developers use to put 518 debugging files into. Enable this option to be able to read and 519 write to these files. 520 521 For detailed documentation on the debugfs API, see 522 Documentation/filesystems/. 523 524 If unsure, say N. 525 526choice 527 prompt "Debugfs default access" 528 depends on DEBUG_FS 529 default DEBUG_FS_ALLOW_ALL 530 help 531 This selects the default access restrictions for debugfs. 532 It can be overridden with kernel command line option 533 debugfs=[on,no-mount,off]. The restrictions apply for API access 534 and filesystem registration. 535 536config DEBUG_FS_ALLOW_ALL 537 bool "Access normal" 538 help 539 No restrictions apply. Both API and filesystem registration 540 is on. This is the normal default operation. 541 542config DEBUG_FS_DISALLOW_MOUNT 543 bool "Do not register debugfs as filesystem" 544 help 545 The API is open but filesystem is not loaded. Clients can still do 546 their work and read with debug tools that do not need 547 debugfs filesystem. 548 549config DEBUG_FS_ALLOW_NONE 550 bool "No access" 551 help 552 Access is off. Clients get -PERM when trying to create nodes in 553 debugfs tree and debugfs is not registered as a filesystem. 554 Client can then back-off or continue without debugfs access. 555 556endchoice 557 558source "lib/Kconfig.kgdb" 559source "lib/Kconfig.ubsan" 560source "lib/Kconfig.kcsan" 561 562endmenu 563 564config DEBUG_KERNEL 565 bool "Kernel debugging" 566 help 567 Say Y here if you are developing drivers or trying to debug and 568 identify kernel problems. 569 570config DEBUG_MISC 571 bool "Miscellaneous debug code" 572 default DEBUG_KERNEL 573 depends on DEBUG_KERNEL 574 help 575 Say Y here if you need to enable miscellaneous debug code that should 576 be under a more specific debug option but isn't. 577 578 579menu "Memory Debugging" 580 581source "mm/Kconfig.debug" 582 583config DEBUG_OBJECTS 584 bool "Debug object operations" 585 depends on DEBUG_KERNEL 586 help 587 If you say Y here, additional code will be inserted into the 588 kernel to track the life time of various objects and validate 589 the operations on those objects. 590 591config DEBUG_OBJECTS_SELFTEST 592 bool "Debug objects selftest" 593 depends on DEBUG_OBJECTS 594 help 595 This enables the selftest of the object debug code. 596 597config DEBUG_OBJECTS_FREE 598 bool "Debug objects in freed memory" 599 depends on DEBUG_OBJECTS 600 help 601 This enables checks whether a k/v free operation frees an area 602 which contains an object which has not been deactivated 603 properly. This can make kmalloc/kfree-intensive workloads 604 much slower. 605 606config DEBUG_OBJECTS_TIMERS 607 bool "Debug timer objects" 608 depends on DEBUG_OBJECTS 609 help 610 If you say Y here, additional code will be inserted into the 611 timer routines to track the life time of timer objects and 612 validate the timer operations. 613 614config DEBUG_OBJECTS_WORK 615 bool "Debug work objects" 616 depends on DEBUG_OBJECTS 617 help 618 If you say Y here, additional code will be inserted into the 619 work queue routines to track the life time of work objects and 620 validate the work operations. 621 622config DEBUG_OBJECTS_RCU_HEAD 623 bool "Debug RCU callbacks objects" 624 depends on DEBUG_OBJECTS 625 help 626 Enable this to turn on debugging of RCU list heads (call_rcu() usage). 627 628config DEBUG_OBJECTS_PERCPU_COUNTER 629 bool "Debug percpu counter objects" 630 depends on DEBUG_OBJECTS 631 help 632 If you say Y here, additional code will be inserted into the 633 percpu counter routines to track the life time of percpu counter 634 objects and validate the percpu counter operations. 635 636config DEBUG_OBJECTS_ENABLE_DEFAULT 637 int "debug_objects bootup default value (0-1)" 638 range 0 1 639 default "1" 640 depends on DEBUG_OBJECTS 641 help 642 Debug objects boot parameter default value 643 644config DEBUG_SLAB 645 bool "Debug slab memory allocations" 646 depends on DEBUG_KERNEL && SLAB 647 help 648 Say Y here to have the kernel do limited verification on memory 649 allocation as well as poisoning memory on free to catch use of freed 650 memory. This can make kmalloc/kfree-intensive workloads much slower. 651 652config SLUB_DEBUG_ON 653 bool "SLUB debugging on by default" 654 depends on SLUB && SLUB_DEBUG 655 default n 656 help 657 Boot with debugging on by default. SLUB boots by default with 658 the runtime debug capabilities switched off. Enabling this is 659 equivalent to specifying the "slub_debug" parameter on boot. 660 There is no support for more fine grained debug control like 661 possible with slub_debug=xxx. SLUB debugging may be switched 662 off in a kernel built with CONFIG_SLUB_DEBUG_ON by specifying 663 "slub_debug=-". 664 665config SLUB_STATS 666 default n 667 bool "Enable SLUB performance statistics" 668 depends on SLUB && SYSFS 669 help 670 SLUB statistics are useful to debug SLUBs allocation behavior in 671 order find ways to optimize the allocator. This should never be 672 enabled for production use since keeping statistics slows down 673 the allocator by a few percentage points. The slabinfo command 674 supports the determination of the most active slabs to figure 675 out which slabs are relevant to a particular load. 676 Try running: slabinfo -DA 677 678config HAVE_DEBUG_KMEMLEAK 679 bool 680 681config DEBUG_KMEMLEAK 682 bool "Kernel memory leak detector" 683 depends on DEBUG_KERNEL && HAVE_DEBUG_KMEMLEAK 684 select DEBUG_FS 685 select STACKTRACE if STACKTRACE_SUPPORT 686 select KALLSYMS 687 select CRC32 688 help 689 Say Y here if you want to enable the memory leak 690 detector. The memory allocation/freeing is traced in a way 691 similar to the Boehm's conservative garbage collector, the 692 difference being that the orphan objects are not freed but 693 only shown in /sys/kernel/debug/kmemleak. Enabling this 694 feature will introduce an overhead to memory 695 allocations. See Documentation/dev-tools/kmemleak.rst for more 696 details. 697 698 Enabling DEBUG_SLAB or SLUB_DEBUG may increase the chances 699 of finding leaks due to the slab objects poisoning. 700 701 In order to access the kmemleak file, debugfs needs to be 702 mounted (usually at /sys/kernel/debug). 703 704config DEBUG_KMEMLEAK_MEM_POOL_SIZE 705 int "Kmemleak memory pool size" 706 depends on DEBUG_KMEMLEAK 707 range 200 1000000 708 default 16000 709 help 710 Kmemleak must track all the memory allocations to avoid 711 reporting false positives. Since memory may be allocated or 712 freed before kmemleak is fully initialised, use a static pool 713 of metadata objects to track such callbacks. After kmemleak is 714 fully initialised, this memory pool acts as an emergency one 715 if slab allocations fail. 716 717config DEBUG_KMEMLEAK_TEST 718 tristate "Simple test for the kernel memory leak detector" 719 depends on DEBUG_KMEMLEAK && m 720 help 721 This option enables a module that explicitly leaks memory. 722 723 If unsure, say N. 724 725config DEBUG_KMEMLEAK_DEFAULT_OFF 726 bool "Default kmemleak to off" 727 depends on DEBUG_KMEMLEAK 728 help 729 Say Y here to disable kmemleak by default. It can then be enabled 730 on the command line via kmemleak=on. 731 732config DEBUG_KMEMLEAK_AUTO_SCAN 733 bool "Enable kmemleak auto scan thread on boot up" 734 default y 735 depends on DEBUG_KMEMLEAK 736 help 737 Depending on the cpu, kmemleak scan may be cpu intensive and can 738 stall user tasks at times. This option enables/disables automatic 739 kmemleak scan at boot up. 740 741 Say N here to disable kmemleak auto scan thread to stop automatic 742 scanning. Disabling this option disables automatic reporting of 743 memory leaks. 744 745 If unsure, say Y. 746 747config DEBUG_STACK_USAGE 748 bool "Stack utilization instrumentation" 749 depends on DEBUG_KERNEL && !IA64 750 help 751 Enables the display of the minimum amount of free stack which each 752 task has ever had available in the sysrq-T and sysrq-P debug output. 753 754 This option will slow down process creation somewhat. 755 756config SCHED_STACK_END_CHECK 757 bool "Detect stack corruption on calls to schedule()" 758 depends on DEBUG_KERNEL 759 default n 760 help 761 This option checks for a stack overrun on calls to schedule(). 762 If the stack end location is found to be over written always panic as 763 the content of the corrupted region can no longer be trusted. 764 This is to ensure no erroneous behaviour occurs which could result in 765 data corruption or a sporadic crash at a later stage once the region 766 is examined. The runtime overhead introduced is minimal. 767 768config ARCH_HAS_DEBUG_VM_PGTABLE 769 bool 770 help 771 An architecture should select this when it can successfully 772 build and run DEBUG_VM_PGTABLE. 773 774config DEBUG_VM 775 bool "Debug VM" 776 depends on DEBUG_KERNEL 777 help 778 Enable this to turn on extended checks in the virtual-memory system 779 that may impact performance. 780 781 If unsure, say N. 782 783config DEBUG_VM_VMACACHE 784 bool "Debug VMA caching" 785 depends on DEBUG_VM 786 help 787 Enable this to turn on VMA caching debug information. Doing so 788 can cause significant overhead, so only enable it in non-production 789 environments. 790 791 If unsure, say N. 792 793config DEBUG_VM_RB 794 bool "Debug VM red-black trees" 795 depends on DEBUG_VM 796 help 797 Enable VM red-black tree debugging information and extra validations. 798 799 If unsure, say N. 800 801config DEBUG_VM_PGFLAGS 802 bool "Debug page-flags operations" 803 depends on DEBUG_VM 804 help 805 Enables extra validation on page flags operations. 806 807 If unsure, say N. 808 809config DEBUG_VM_PGTABLE 810 bool "Debug arch page table for semantics compliance" 811 depends on MMU 812 depends on ARCH_HAS_DEBUG_VM_PGTABLE 813 default y if DEBUG_VM 814 help 815 This option provides a debug method which can be used to test 816 architecture page table helper functions on various platforms in 817 verifying if they comply with expected generic MM semantics. This 818 will help architecture code in making sure that any changes or 819 new additions of these helpers still conform to expected 820 semantics of the generic MM. Platforms will have to opt in for 821 this through ARCH_HAS_DEBUG_VM_PGTABLE. 822 823 If unsure, say N. 824 825config ARCH_HAS_DEBUG_VIRTUAL 826 bool 827 828config DEBUG_VIRTUAL 829 bool "Debug VM translations" 830 depends on DEBUG_KERNEL && ARCH_HAS_DEBUG_VIRTUAL 831 help 832 Enable some costly sanity checks in virtual to page code. This can 833 catch mistakes with virt_to_page() and friends. 834 835 If unsure, say N. 836 837config DEBUG_NOMMU_REGIONS 838 bool "Debug the global anon/private NOMMU mapping region tree" 839 depends on DEBUG_KERNEL && !MMU 840 help 841 This option causes the global tree of anonymous and private mapping 842 regions to be regularly checked for invalid topology. 843 844config DEBUG_MEMORY_INIT 845 bool "Debug memory initialisation" if EXPERT 846 default !EXPERT 847 help 848 Enable this for additional checks during memory initialisation. 849 The sanity checks verify aspects of the VM such as the memory model 850 and other information provided by the architecture. Verbose 851 information will be printed at KERN_DEBUG loglevel depending 852 on the mminit_loglevel= command-line option. 853 854 If unsure, say Y 855 856config MEMORY_NOTIFIER_ERROR_INJECT 857 tristate "Memory hotplug notifier error injection module" 858 depends on MEMORY_HOTPLUG_SPARSE && NOTIFIER_ERROR_INJECTION 859 help 860 This option provides the ability to inject artificial errors to 861 memory hotplug notifier chain callbacks. It is controlled through 862 debugfs interface under /sys/kernel/debug/notifier-error-inject/memory 863 864 If the notifier call chain should be failed with some events 865 notified, write the error code to "actions/<notifier event>/error". 866 867 Example: Inject memory hotplug offline error (-12 == -ENOMEM) 868 869 # cd /sys/kernel/debug/notifier-error-inject/memory 870 # echo -12 > actions/MEM_GOING_OFFLINE/error 871 # echo offline > /sys/devices/system/memory/memoryXXX/state 872 bash: echo: write error: Cannot allocate memory 873 874 To compile this code as a module, choose M here: the module will 875 be called memory-notifier-error-inject. 876 877 If unsure, say N. 878 879config DEBUG_PER_CPU_MAPS 880 bool "Debug access to per_cpu maps" 881 depends on DEBUG_KERNEL 882 depends on SMP 883 help 884 Say Y to verify that the per_cpu map being accessed has 885 been set up. This adds a fair amount of code to kernel memory 886 and decreases performance. 887 888 Say N if unsure. 889 890config DEBUG_KMAP_LOCAL 891 bool "Debug kmap_local temporary mappings" 892 depends on DEBUG_KERNEL && KMAP_LOCAL 893 help 894 This option enables additional error checking for the kmap_local 895 infrastructure. Disable for production use. 896 897config ARCH_SUPPORTS_KMAP_LOCAL_FORCE_MAP 898 bool 899 900config DEBUG_KMAP_LOCAL_FORCE_MAP 901 bool "Enforce kmap_local temporary mappings" 902 depends on DEBUG_KERNEL && ARCH_SUPPORTS_KMAP_LOCAL_FORCE_MAP 903 select KMAP_LOCAL 904 select DEBUG_KMAP_LOCAL 905 help 906 This option enforces temporary mappings through the kmap_local 907 mechanism for non-highmem pages and on non-highmem systems. 908 Disable this for production systems! 909 910config DEBUG_HIGHMEM 911 bool "Highmem debugging" 912 depends on DEBUG_KERNEL && HIGHMEM 913 select DEBUG_KMAP_LOCAL_FORCE_MAP if ARCH_SUPPORTS_KMAP_LOCAL_FORCE_MAP 914 select DEBUG_KMAP_LOCAL 915 help 916 This option enables additional error checking for high memory 917 systems. Disable for production systems. 918 919config HAVE_DEBUG_STACKOVERFLOW 920 bool 921 922config DEBUG_STACKOVERFLOW 923 bool "Check for stack overflows" 924 depends on DEBUG_KERNEL && HAVE_DEBUG_STACKOVERFLOW 925 help 926 Say Y here if you want to check for overflows of kernel, IRQ 927 and exception stacks (if your architecture uses them). This 928 option will show detailed messages if free stack space drops 929 below a certain limit. 930 931 These kinds of bugs usually occur when call-chains in the 932 kernel get too deep, especially when interrupts are 933 involved. 934 935 Use this in cases where you see apparently random memory 936 corruption, especially if it appears in 'struct thread_info' 937 938 If in doubt, say "N". 939 940source "lib/Kconfig.kasan" 941source "lib/Kconfig.kfence" 942 943endmenu # "Memory Debugging" 944 945config DEBUG_SHIRQ 946 bool "Debug shared IRQ handlers" 947 depends on DEBUG_KERNEL 948 help 949 Enable this to generate a spurious interrupt just before a shared 950 interrupt handler is deregistered (generating one when registering 951 is currently disabled). Drivers need to handle this correctly. Some 952 don't and need to be caught. 953 954menu "Debug Oops, Lockups and Hangs" 955 956config PANIC_ON_OOPS 957 bool "Panic on Oops" 958 help 959 Say Y here to enable the kernel to panic when it oopses. This 960 has the same effect as setting oops=panic on the kernel command 961 line. 962 963 This feature is useful to ensure that the kernel does not do 964 anything erroneous after an oops which could result in data 965 corruption or other issues. 966 967 Say N if unsure. 968 969config PANIC_ON_OOPS_VALUE 970 int 971 range 0 1 972 default 0 if !PANIC_ON_OOPS 973 default 1 if PANIC_ON_OOPS 974 975config PANIC_TIMEOUT 976 int "panic timeout" 977 default 0 978 help 979 Set the timeout value (in seconds) until a reboot occurs when 980 the kernel panics. If n = 0, then we wait forever. A timeout 981 value n > 0 will wait n seconds before rebooting, while a timeout 982 value n < 0 will reboot immediately. 983 984config LOCKUP_DETECTOR 985 bool 986 987config SOFTLOCKUP_DETECTOR 988 bool "Detect Soft Lockups" 989 depends on DEBUG_KERNEL && !S390 990 select LOCKUP_DETECTOR 991 help 992 Say Y here to enable the kernel to act as a watchdog to detect 993 soft lockups. 994 995 Softlockups are bugs that cause the kernel to loop in kernel 996 mode for more than 20 seconds, without giving other tasks a 997 chance to run. The current stack trace is displayed upon 998 detection and the system will stay locked up. 999 1000config BOOTPARAM_SOFTLOCKUP_PANIC 1001 bool "Panic (Reboot) On Soft Lockups" 1002 depends on SOFTLOCKUP_DETECTOR 1003 help 1004 Say Y here to enable the kernel to panic on "soft lockups", 1005 which are bugs that cause the kernel to loop in kernel 1006 mode for more than 20 seconds (configurable using the watchdog_thresh 1007 sysctl), without giving other tasks a chance to run. 1008 1009 The panic can be used in combination with panic_timeout, 1010 to cause the system to reboot automatically after a 1011 lockup has been detected. This feature is useful for 1012 high-availability systems that have uptime guarantees and 1013 where a lockup must be resolved ASAP. 1014 1015 Say N if unsure. 1016 1017config BOOTPARAM_SOFTLOCKUP_PANIC_VALUE 1018 int 1019 depends on SOFTLOCKUP_DETECTOR 1020 range 0 1 1021 default 0 if !BOOTPARAM_SOFTLOCKUP_PANIC 1022 default 1 if BOOTPARAM_SOFTLOCKUP_PANIC 1023 1024config HARDLOCKUP_DETECTOR_PERF 1025 bool 1026 select SOFTLOCKUP_DETECTOR 1027 1028# 1029# Enables a timestamp based low pass filter to compensate for perf based 1030# hard lockup detection which runs too fast due to turbo modes. 1031# 1032config HARDLOCKUP_CHECK_TIMESTAMP 1033 bool 1034 1035# 1036# arch/ can define HAVE_HARDLOCKUP_DETECTOR_ARCH to provide their own hard 1037# lockup detector rather than the perf based detector. 1038# 1039config HARDLOCKUP_DETECTOR 1040 bool "Detect Hard Lockups" 1041 depends on DEBUG_KERNEL && !S390 1042 depends on HAVE_HARDLOCKUP_DETECTOR_PERF || HAVE_HARDLOCKUP_DETECTOR_ARCH 1043 select LOCKUP_DETECTOR 1044 select HARDLOCKUP_DETECTOR_PERF if HAVE_HARDLOCKUP_DETECTOR_PERF 1045 select HARDLOCKUP_DETECTOR_ARCH if HAVE_HARDLOCKUP_DETECTOR_ARCH 1046 help 1047 Say Y here to enable the kernel to act as a watchdog to detect 1048 hard lockups. 1049 1050 Hardlockups are bugs that cause the CPU to loop in kernel mode 1051 for more than 10 seconds, without letting other interrupts have a 1052 chance to run. The current stack trace is displayed upon detection 1053 and the system will stay locked up. 1054 1055config BOOTPARAM_HARDLOCKUP_PANIC 1056 bool "Panic (Reboot) On Hard Lockups" 1057 depends on HARDLOCKUP_DETECTOR 1058 help 1059 Say Y here to enable the kernel to panic on "hard lockups", 1060 which are bugs that cause the kernel to loop in kernel 1061 mode with interrupts disabled for more than 10 seconds (configurable 1062 using the watchdog_thresh sysctl). 1063 1064 Say N if unsure. 1065 1066config BOOTPARAM_HARDLOCKUP_PANIC_VALUE 1067 int 1068 depends on HARDLOCKUP_DETECTOR 1069 range 0 1 1070 default 0 if !BOOTPARAM_HARDLOCKUP_PANIC 1071 default 1 if BOOTPARAM_HARDLOCKUP_PANIC 1072 1073config DETECT_HUNG_TASK 1074 bool "Detect Hung Tasks" 1075 depends on DEBUG_KERNEL 1076 default SOFTLOCKUP_DETECTOR 1077 help 1078 Say Y here to enable the kernel to detect "hung tasks", 1079 which are bugs that cause the task to be stuck in 1080 uninterruptible "D" state indefinitely. 1081 1082 When a hung task is detected, the kernel will print the 1083 current stack trace (which you should report), but the 1084 task will stay in uninterruptible state. If lockdep is 1085 enabled then all held locks will also be reported. This 1086 feature has negligible overhead. 1087 1088config DEFAULT_HUNG_TASK_TIMEOUT 1089 int "Default timeout for hung task detection (in seconds)" 1090 depends on DETECT_HUNG_TASK 1091 default 120 1092 help 1093 This option controls the default timeout (in seconds) used 1094 to determine when a task has become non-responsive and should 1095 be considered hung. 1096 1097 It can be adjusted at runtime via the kernel.hung_task_timeout_secs 1098 sysctl or by writing a value to 1099 /proc/sys/kernel/hung_task_timeout_secs. 1100 1101 A timeout of 0 disables the check. The default is two minutes. 1102 Keeping the default should be fine in most cases. 1103 1104config BOOTPARAM_HUNG_TASK_PANIC 1105 bool "Panic (Reboot) On Hung Tasks" 1106 depends on DETECT_HUNG_TASK 1107 help 1108 Say Y here to enable the kernel to panic on "hung tasks", 1109 which are bugs that cause the kernel to leave a task stuck 1110 in uninterruptible "D" state. 1111 1112 The panic can be used in combination with panic_timeout, 1113 to cause the system to reboot automatically after a 1114 hung task has been detected. This feature is useful for 1115 high-availability systems that have uptime guarantees and 1116 where a hung tasks must be resolved ASAP. 1117 1118 Say N if unsure. 1119 1120config BOOTPARAM_HUNG_TASK_PANIC_VALUE 1121 int 1122 depends on DETECT_HUNG_TASK 1123 range 0 1 1124 default 0 if !BOOTPARAM_HUNG_TASK_PANIC 1125 default 1 if BOOTPARAM_HUNG_TASK_PANIC 1126 1127config WQ_WATCHDOG 1128 bool "Detect Workqueue Stalls" 1129 depends on DEBUG_KERNEL 1130 help 1131 Say Y here to enable stall detection on workqueues. If a 1132 worker pool doesn't make forward progress on a pending work 1133 item for over a given amount of time, 30s by default, a 1134 warning message is printed along with dump of workqueue 1135 state. This can be configured through kernel parameter 1136 "workqueue.watchdog_thresh" and its sysfs counterpart. 1137 1138config TEST_LOCKUP 1139 tristate "Test module to generate lockups" 1140 depends on m 1141 help 1142 This builds the "test_lockup" module that helps to make sure 1143 that watchdogs and lockup detectors are working properly. 1144 1145 Depending on module parameters it could emulate soft or hard 1146 lockup, "hung task", or locking arbitrary lock for a long time. 1147 Also it could generate series of lockups with cooling-down periods. 1148 1149 If unsure, say N. 1150 1151endmenu # "Debug lockups and hangs" 1152 1153menu "Scheduler Debugging" 1154 1155config SCHED_DEBUG 1156 bool "Collect scheduler debugging info" 1157 depends on DEBUG_KERNEL && PROC_FS 1158 default y 1159 help 1160 If you say Y here, the /proc/sched_debug file will be provided 1161 that can help debug the scheduler. The runtime overhead of this 1162 option is minimal. 1163 1164config SCHED_INFO 1165 bool 1166 default n 1167 1168config SCHEDSTATS 1169 bool "Collect scheduler statistics" 1170 depends on DEBUG_KERNEL && PROC_FS 1171 select SCHED_INFO 1172 help 1173 If you say Y here, additional code will be inserted into the 1174 scheduler and related routines to collect statistics about 1175 scheduler behavior and provide them in /proc/schedstat. These 1176 stats may be useful for both tuning and debugging the scheduler 1177 If you aren't debugging the scheduler or trying to tune a specific 1178 application, you can say N to avoid the very slight overhead 1179 this adds. 1180 1181endmenu 1182 1183config DEBUG_TIMEKEEPING 1184 bool "Enable extra timekeeping sanity checking" 1185 help 1186 This option will enable additional timekeeping sanity checks 1187 which may be helpful when diagnosing issues where timekeeping 1188 problems are suspected. 1189 1190 This may include checks in the timekeeping hotpaths, so this 1191 option may have a (very small) performance impact to some 1192 workloads. 1193 1194 If unsure, say N. 1195 1196config DEBUG_PREEMPT 1197 bool "Debug preemptible kernel" 1198 depends on DEBUG_KERNEL && PREEMPTION && TRACE_IRQFLAGS_SUPPORT 1199 default y 1200 help 1201 If you say Y here then the kernel will use a debug variant of the 1202 commonly used smp_processor_id() function and will print warnings 1203 if kernel code uses it in a preemption-unsafe way. Also, the kernel 1204 will detect preemption count underflows. 1205 1206menu "Lock Debugging (spinlocks, mutexes, etc...)" 1207 1208config LOCK_DEBUGGING_SUPPORT 1209 bool 1210 depends on TRACE_IRQFLAGS_SUPPORT && STACKTRACE_SUPPORT && LOCKDEP_SUPPORT 1211 default y 1212 1213config PROVE_LOCKING 1214 bool "Lock debugging: prove locking correctness" 1215 depends on DEBUG_KERNEL && LOCK_DEBUGGING_SUPPORT 1216 select LOCKDEP 1217 select DEBUG_SPINLOCK 1218 select DEBUG_MUTEXES 1219 select DEBUG_RT_MUTEXES if RT_MUTEXES 1220 select DEBUG_RWSEMS 1221 select DEBUG_WW_MUTEX_SLOWPATH 1222 select DEBUG_LOCK_ALLOC 1223 select PREEMPT_COUNT if !ARCH_NO_PREEMPT 1224 select TRACE_IRQFLAGS 1225 default n 1226 help 1227 This feature enables the kernel to prove that all locking 1228 that occurs in the kernel runtime is mathematically 1229 correct: that under no circumstance could an arbitrary (and 1230 not yet triggered) combination of observed locking 1231 sequences (on an arbitrary number of CPUs, running an 1232 arbitrary number of tasks and interrupt contexts) cause a 1233 deadlock. 1234 1235 In short, this feature enables the kernel to report locking 1236 related deadlocks before they actually occur. 1237 1238 The proof does not depend on how hard and complex a 1239 deadlock scenario would be to trigger: how many 1240 participant CPUs, tasks and irq-contexts would be needed 1241 for it to trigger. The proof also does not depend on 1242 timing: if a race and a resulting deadlock is possible 1243 theoretically (no matter how unlikely the race scenario 1244 is), it will be proven so and will immediately be 1245 reported by the kernel (once the event is observed that 1246 makes the deadlock theoretically possible). 1247 1248 If a deadlock is impossible (i.e. the locking rules, as 1249 observed by the kernel, are mathematically correct), the 1250 kernel reports nothing. 1251 1252 NOTE: this feature can also be enabled for rwlocks, mutexes 1253 and rwsems - in which case all dependencies between these 1254 different locking variants are observed and mapped too, and 1255 the proof of observed correctness is also maintained for an 1256 arbitrary combination of these separate locking variants. 1257 1258 For more details, see Documentation/locking/lockdep-design.rst. 1259 1260config PROVE_RAW_LOCK_NESTING 1261 bool "Enable raw_spinlock - spinlock nesting checks" 1262 depends on PROVE_LOCKING 1263 default n 1264 help 1265 Enable the raw_spinlock vs. spinlock nesting checks which ensure 1266 that the lock nesting rules for PREEMPT_RT enabled kernels are 1267 not violated. 1268 1269 NOTE: There are known nesting problems. So if you enable this 1270 option expect lockdep splats until these problems have been fully 1271 addressed which is work in progress. This config switch allows to 1272 identify and analyze these problems. It will be removed and the 1273 check permanentely enabled once the main issues have been fixed. 1274 1275 If unsure, select N. 1276 1277config LOCK_STAT 1278 bool "Lock usage statistics" 1279 depends on DEBUG_KERNEL && LOCK_DEBUGGING_SUPPORT 1280 select LOCKDEP 1281 select DEBUG_SPINLOCK 1282 select DEBUG_MUTEXES 1283 select DEBUG_RT_MUTEXES if RT_MUTEXES 1284 select DEBUG_LOCK_ALLOC 1285 default n 1286 help 1287 This feature enables tracking lock contention points 1288 1289 For more details, see Documentation/locking/lockstat.rst 1290 1291 This also enables lock events required by "perf lock", 1292 subcommand of perf. 1293 If you want to use "perf lock", you also need to turn on 1294 CONFIG_EVENT_TRACING. 1295 1296 CONFIG_LOCK_STAT defines "contended" and "acquired" lock events. 1297 (CONFIG_LOCKDEP defines "acquire" and "release" events.) 1298 1299config DEBUG_RT_MUTEXES 1300 bool "RT Mutex debugging, deadlock detection" 1301 depends on DEBUG_KERNEL && RT_MUTEXES 1302 help 1303 This allows rt mutex semantics violations and rt mutex related 1304 deadlocks (lockups) to be detected and reported automatically. 1305 1306config DEBUG_SPINLOCK 1307 bool "Spinlock and rw-lock debugging: basic checks" 1308 depends on DEBUG_KERNEL 1309 select UNINLINE_SPIN_UNLOCK 1310 help 1311 Say Y here and build SMP to catch missing spinlock initialization 1312 and certain other kinds of spinlock errors commonly made. This is 1313 best used in conjunction with the NMI watchdog so that spinlock 1314 deadlocks are also debuggable. 1315 1316config DEBUG_MUTEXES 1317 bool "Mutex debugging: basic checks" 1318 depends on DEBUG_KERNEL 1319 help 1320 This feature allows mutex semantics violations to be detected and 1321 reported. 1322 1323config DEBUG_WW_MUTEX_SLOWPATH 1324 bool "Wait/wound mutex debugging: Slowpath testing" 1325 depends on DEBUG_KERNEL && LOCK_DEBUGGING_SUPPORT 1326 select DEBUG_LOCK_ALLOC 1327 select DEBUG_SPINLOCK 1328 select DEBUG_MUTEXES 1329 help 1330 This feature enables slowpath testing for w/w mutex users by 1331 injecting additional -EDEADLK wound/backoff cases. Together with 1332 the full mutex checks enabled with (CONFIG_PROVE_LOCKING) this 1333 will test all possible w/w mutex interface abuse with the 1334 exception of simply not acquiring all the required locks. 1335 Note that this feature can introduce significant overhead, so 1336 it really should not be enabled in a production or distro kernel, 1337 even a debug kernel. If you are a driver writer, enable it. If 1338 you are a distro, do not. 1339 1340config DEBUG_RWSEMS 1341 bool "RW Semaphore debugging: basic checks" 1342 depends on DEBUG_KERNEL 1343 help 1344 This debugging feature allows mismatched rw semaphore locks 1345 and unlocks to be detected and reported. 1346 1347config DEBUG_LOCK_ALLOC 1348 bool "Lock debugging: detect incorrect freeing of live locks" 1349 depends on DEBUG_KERNEL && LOCK_DEBUGGING_SUPPORT 1350 select DEBUG_SPINLOCK 1351 select DEBUG_MUTEXES 1352 select DEBUG_RT_MUTEXES if RT_MUTEXES 1353 select LOCKDEP 1354 help 1355 This feature will check whether any held lock (spinlock, rwlock, 1356 mutex or rwsem) is incorrectly freed by the kernel, via any of the 1357 memory-freeing routines (kfree(), kmem_cache_free(), free_pages(), 1358 vfree(), etc.), whether a live lock is incorrectly reinitialized via 1359 spin_lock_init()/mutex_init()/etc., or whether there is any lock 1360 held during task exit. 1361 1362config LOCKDEP 1363 bool 1364 depends on DEBUG_KERNEL && LOCK_DEBUGGING_SUPPORT 1365 select STACKTRACE 1366 depends on FRAME_POINTER || MIPS || PPC || S390 || MICROBLAZE || ARM || ARC || X86 1367 select KALLSYMS 1368 select KALLSYMS_ALL 1369 1370config LOCKDEP_SMALL 1371 bool 1372 1373config DEBUG_LOCKDEP 1374 bool "Lock dependency engine debugging" 1375 depends on DEBUG_KERNEL && LOCKDEP 1376 select DEBUG_IRQFLAGS 1377 help 1378 If you say Y here, the lock dependency engine will do 1379 additional runtime checks to debug itself, at the price 1380 of more runtime overhead. 1381 1382config DEBUG_ATOMIC_SLEEP 1383 bool "Sleep inside atomic section checking" 1384 select PREEMPT_COUNT 1385 depends on DEBUG_KERNEL 1386 depends on !ARCH_NO_PREEMPT 1387 help 1388 If you say Y here, various routines which may sleep will become very 1389 noisy if they are called inside atomic sections: when a spinlock is 1390 held, inside an rcu read side critical section, inside preempt disabled 1391 sections, inside an interrupt, etc... 1392 1393config DEBUG_LOCKING_API_SELFTESTS 1394 bool "Locking API boot-time self-tests" 1395 depends on DEBUG_KERNEL 1396 help 1397 Say Y here if you want the kernel to run a short self-test during 1398 bootup. The self-test checks whether common types of locking bugs 1399 are detected by debugging mechanisms or not. (if you disable 1400 lock debugging then those bugs wont be detected of course.) 1401 The following locking APIs are covered: spinlocks, rwlocks, 1402 mutexes and rwsems. 1403 1404config LOCK_TORTURE_TEST 1405 tristate "torture tests for locking" 1406 depends on DEBUG_KERNEL 1407 select TORTURE_TEST 1408 help 1409 This option provides a kernel module that runs torture tests 1410 on kernel locking primitives. The kernel module may be built 1411 after the fact on the running kernel to be tested, if desired. 1412 1413 Say Y here if you want kernel locking-primitive torture tests 1414 to be built into the kernel. 1415 Say M if you want these torture tests to build as a module. 1416 Say N if you are unsure. 1417 1418config WW_MUTEX_SELFTEST 1419 tristate "Wait/wound mutex selftests" 1420 help 1421 This option provides a kernel module that runs tests on the 1422 on the struct ww_mutex locking API. 1423 1424 It is recommended to enable DEBUG_WW_MUTEX_SLOWPATH in conjunction 1425 with this test harness. 1426 1427 Say M if you want these self tests to build as a module. 1428 Say N if you are unsure. 1429 1430config SCF_TORTURE_TEST 1431 tristate "torture tests for smp_call_function*()" 1432 depends on DEBUG_KERNEL 1433 select TORTURE_TEST 1434 help 1435 This option provides a kernel module that runs torture tests 1436 on the smp_call_function() family of primitives. The kernel 1437 module may be built after the fact on the running kernel to 1438 be tested, if desired. 1439 1440config CSD_LOCK_WAIT_DEBUG 1441 bool "Debugging for csd_lock_wait(), called from smp_call_function*()" 1442 depends on DEBUG_KERNEL 1443 depends on 64BIT 1444 default n 1445 help 1446 This option enables debug prints when CPUs are slow to respond 1447 to the smp_call_function*() IPI wrappers. These debug prints 1448 include the IPI handler function currently executing (if any) 1449 and relevant stack traces. 1450 1451endmenu # lock debugging 1452 1453config TRACE_IRQFLAGS 1454 depends on TRACE_IRQFLAGS_SUPPORT 1455 bool 1456 help 1457 Enables hooks to interrupt enabling and disabling for 1458 either tracing or lock debugging. 1459 1460config TRACE_IRQFLAGS_NMI 1461 def_bool y 1462 depends on TRACE_IRQFLAGS 1463 depends on TRACE_IRQFLAGS_NMI_SUPPORT 1464 1465config DEBUG_IRQFLAGS 1466 bool "Debug IRQ flag manipulation" 1467 help 1468 Enables checks for potentially unsafe enabling or disabling of 1469 interrupts, such as calling raw_local_irq_restore() when interrupts 1470 are enabled. 1471 1472config STACKTRACE 1473 bool "Stack backtrace support" 1474 depends on STACKTRACE_SUPPORT 1475 help 1476 This option causes the kernel to create a /proc/pid/stack for 1477 every process, showing its current stack trace. 1478 It is also used by various kernel debugging features that require 1479 stack trace generation. 1480 1481config WARN_ALL_UNSEEDED_RANDOM 1482 bool "Warn for all uses of unseeded randomness" 1483 default n 1484 help 1485 Some parts of the kernel contain bugs relating to their use of 1486 cryptographically secure random numbers before it's actually possible 1487 to generate those numbers securely. This setting ensures that these 1488 flaws don't go unnoticed, by enabling a message, should this ever 1489 occur. This will allow people with obscure setups to know when things 1490 are going wrong, so that they might contact developers about fixing 1491 it. 1492 1493 Unfortunately, on some models of some architectures getting 1494 a fully seeded CRNG is extremely difficult, and so this can 1495 result in dmesg getting spammed for a surprisingly long 1496 time. This is really bad from a security perspective, and 1497 so architecture maintainers really need to do what they can 1498 to get the CRNG seeded sooner after the system is booted. 1499 However, since users cannot do anything actionable to 1500 address this, by default the kernel will issue only a single 1501 warning for the first use of unseeded randomness. 1502 1503 Say Y here if you want to receive warnings for all uses of 1504 unseeded randomness. This will be of use primarily for 1505 those developers interested in improving the security of 1506 Linux kernels running on their architecture (or 1507 subarchitecture). 1508 1509config DEBUG_KOBJECT 1510 bool "kobject debugging" 1511 depends on DEBUG_KERNEL 1512 help 1513 If you say Y here, some extra kobject debugging messages will be sent 1514 to the syslog. 1515 1516config DEBUG_KOBJECT_RELEASE 1517 bool "kobject release debugging" 1518 depends on DEBUG_OBJECTS_TIMERS 1519 help 1520 kobjects are reference counted objects. This means that their 1521 last reference count put is not predictable, and the kobject can 1522 live on past the point at which a driver decides to drop it's 1523 initial reference to the kobject gained on allocation. An 1524 example of this would be a struct device which has just been 1525 unregistered. 1526 1527 However, some buggy drivers assume that after such an operation, 1528 the memory backing the kobject can be immediately freed. This 1529 goes completely against the principles of a refcounted object. 1530 1531 If you say Y here, the kernel will delay the release of kobjects 1532 on the last reference count to improve the visibility of this 1533 kind of kobject release bug. 1534 1535config HAVE_DEBUG_BUGVERBOSE 1536 bool 1537 1538menu "Debug kernel data structures" 1539 1540config DEBUG_LIST 1541 bool "Debug linked list manipulation" 1542 depends on DEBUG_KERNEL || BUG_ON_DATA_CORRUPTION 1543 help 1544 Enable this to turn on extended checks in the linked-list 1545 walking routines. 1546 1547 If unsure, say N. 1548 1549config DEBUG_PLIST 1550 bool "Debug priority linked list manipulation" 1551 depends on DEBUG_KERNEL 1552 help 1553 Enable this to turn on extended checks in the priority-ordered 1554 linked-list (plist) walking routines. This checks the entire 1555 list multiple times during each manipulation. 1556 1557 If unsure, say N. 1558 1559config DEBUG_SG 1560 bool "Debug SG table operations" 1561 depends on DEBUG_KERNEL 1562 help 1563 Enable this to turn on checks on scatter-gather tables. This can 1564 help find problems with drivers that do not properly initialize 1565 their sg tables. 1566 1567 If unsure, say N. 1568 1569config DEBUG_NOTIFIERS 1570 bool "Debug notifier call chains" 1571 depends on DEBUG_KERNEL 1572 help 1573 Enable this to turn on sanity checking for notifier call chains. 1574 This is most useful for kernel developers to make sure that 1575 modules properly unregister themselves from notifier chains. 1576 This is a relatively cheap check but if you care about maximum 1577 performance, say N. 1578 1579config BUG_ON_DATA_CORRUPTION 1580 bool "Trigger a BUG when data corruption is detected" 1581 select DEBUG_LIST 1582 help 1583 Select this option if the kernel should BUG when it encounters 1584 data corruption in kernel memory structures when they get checked 1585 for validity. 1586 1587 If unsure, say N. 1588 1589endmenu 1590 1591config DEBUG_CREDENTIALS 1592 bool "Debug credential management" 1593 depends on DEBUG_KERNEL 1594 help 1595 Enable this to turn on some debug checking for credential 1596 management. The additional code keeps track of the number of 1597 pointers from task_structs to any given cred struct, and checks to 1598 see that this number never exceeds the usage count of the cred 1599 struct. 1600 1601 Furthermore, if SELinux is enabled, this also checks that the 1602 security pointer in the cred struct is never seen to be invalid. 1603 1604 If unsure, say N. 1605 1606source "kernel/rcu/Kconfig.debug" 1607 1608config DEBUG_WQ_FORCE_RR_CPU 1609 bool "Force round-robin CPU selection for unbound work items" 1610 depends on DEBUG_KERNEL 1611 default n 1612 help 1613 Workqueue used to implicitly guarantee that work items queued 1614 without explicit CPU specified are put on the local CPU. This 1615 guarantee is no longer true and while local CPU is still 1616 preferred work items may be put on foreign CPUs. Kernel 1617 parameter "workqueue.debug_force_rr_cpu" is added to force 1618 round-robin CPU selection to flush out usages which depend on the 1619 now broken guarantee. This config option enables the debug 1620 feature by default. When enabled, memory and cache locality will 1621 be impacted. 1622 1623config DEBUG_BLOCK_EXT_DEVT 1624 bool "Force extended block device numbers and spread them" 1625 depends on DEBUG_KERNEL 1626 depends on BLOCK 1627 default n 1628 help 1629 BIG FAT WARNING: ENABLING THIS OPTION MIGHT BREAK BOOTING ON 1630 SOME DISTRIBUTIONS. DO NOT ENABLE THIS UNLESS YOU KNOW WHAT 1631 YOU ARE DOING. Distros, please enable this and fix whatever 1632 is broken. 1633 1634 Conventionally, block device numbers are allocated from 1635 predetermined contiguous area. However, extended block area 1636 may introduce non-contiguous block device numbers. This 1637 option forces most block device numbers to be allocated from 1638 the extended space and spreads them to discover kernel or 1639 userland code paths which assume predetermined contiguous 1640 device number allocation. 1641 1642 Note that turning on this debug option shuffles all the 1643 device numbers for all IDE and SCSI devices including libata 1644 ones, so root partition specified using device number 1645 directly (via rdev or root=MAJ:MIN) won't work anymore. 1646 Textual device names (root=/dev/sdXn) will continue to work. 1647 1648 Say N if you are unsure. 1649 1650config CPU_HOTPLUG_STATE_CONTROL 1651 bool "Enable CPU hotplug state control" 1652 depends on DEBUG_KERNEL 1653 depends on HOTPLUG_CPU 1654 default n 1655 help 1656 Allows to write steps between "offline" and "online" to the CPUs 1657 sysfs target file so states can be stepped granular. This is a debug 1658 option for now as the hotplug machinery cannot be stopped and 1659 restarted at arbitrary points yet. 1660 1661 Say N if your are unsure. 1662 1663config LATENCYTOP 1664 bool "Latency measuring infrastructure" 1665 depends on DEBUG_KERNEL 1666 depends on STACKTRACE_SUPPORT 1667 depends on PROC_FS 1668 depends on FRAME_POINTER || MIPS || PPC || S390 || MICROBLAZE || ARM || ARC || X86 1669 select KALLSYMS 1670 select KALLSYMS_ALL 1671 select STACKTRACE 1672 select SCHEDSTATS 1673 select SCHED_DEBUG 1674 help 1675 Enable this option if you want to use the LatencyTOP tool 1676 to find out which userspace is blocking on what kernel operations. 1677 1678source "kernel/trace/Kconfig" 1679 1680config PROVIDE_OHCI1394_DMA_INIT 1681 bool "Remote debugging over FireWire early on boot" 1682 depends on PCI && X86 1683 help 1684 If you want to debug problems which hang or crash the kernel early 1685 on boot and the crashing machine has a FireWire port, you can use 1686 this feature to remotely access the memory of the crashed machine 1687 over FireWire. This employs remote DMA as part of the OHCI1394 1688 specification which is now the standard for FireWire controllers. 1689 1690 With remote DMA, you can monitor the printk buffer remotely using 1691 firescope and access all memory below 4GB using fireproxy from gdb. 1692 Even controlling a kernel debugger is possible using remote DMA. 1693 1694 Usage: 1695 1696 If ohci1394_dma=early is used as boot parameter, it will initialize 1697 all OHCI1394 controllers which are found in the PCI config space. 1698 1699 As all changes to the FireWire bus such as enabling and disabling 1700 devices cause a bus reset and thereby disable remote DMA for all 1701 devices, be sure to have the cable plugged and FireWire enabled on 1702 the debugging host before booting the debug target for debugging. 1703 1704 This code (~1k) is freed after boot. By then, the firewire stack 1705 in charge of the OHCI-1394 controllers should be used instead. 1706 1707 See Documentation/core-api/debugging-via-ohci1394.rst for more information. 1708 1709source "samples/Kconfig" 1710 1711config ARCH_HAS_DEVMEM_IS_ALLOWED 1712 bool 1713 1714config STRICT_DEVMEM 1715 bool "Filter access to /dev/mem" 1716 depends on MMU && DEVMEM 1717 depends on ARCH_HAS_DEVMEM_IS_ALLOWED || GENERIC_LIB_DEVMEM_IS_ALLOWED 1718 default y if PPC || X86 || ARM64 1719 help 1720 If this option is disabled, you allow userspace (root) access to all 1721 of memory, including kernel and userspace memory. Accidental 1722 access to this is obviously disastrous, but specific access can 1723 be used by people debugging the kernel. Note that with PAT support 1724 enabled, even in this case there are restrictions on /dev/mem 1725 use due to the cache aliasing requirements. 1726 1727 If this option is switched on, and IO_STRICT_DEVMEM=n, the /dev/mem 1728 file only allows userspace access to PCI space and the BIOS code and 1729 data regions. This is sufficient for dosemu and X and all common 1730 users of /dev/mem. 1731 1732 If in doubt, say Y. 1733 1734config IO_STRICT_DEVMEM 1735 bool "Filter I/O access to /dev/mem" 1736 depends on STRICT_DEVMEM 1737 help 1738 If this option is disabled, you allow userspace (root) access to all 1739 io-memory regardless of whether a driver is actively using that 1740 range. Accidental access to this is obviously disastrous, but 1741 specific access can be used by people debugging kernel drivers. 1742 1743 If this option is switched on, the /dev/mem file only allows 1744 userspace access to *idle* io-memory ranges (see /proc/iomem) This 1745 may break traditional users of /dev/mem (dosemu, legacy X, etc...) 1746 if the driver using a given range cannot be disabled. 1747 1748 If in doubt, say Y. 1749 1750menu "$(SRCARCH) Debugging" 1751 1752source "arch/$(SRCARCH)/Kconfig.debug" 1753 1754endmenu 1755 1756menu "Kernel Testing and Coverage" 1757 1758source "lib/kunit/Kconfig" 1759 1760config NOTIFIER_ERROR_INJECTION 1761 tristate "Notifier error injection" 1762 depends on DEBUG_KERNEL 1763 select DEBUG_FS 1764 help 1765 This option provides the ability to inject artificial errors to 1766 specified notifier chain callbacks. It is useful to test the error 1767 handling of notifier call chain failures. 1768 1769 Say N if unsure. 1770 1771config PM_NOTIFIER_ERROR_INJECT 1772 tristate "PM notifier error injection module" 1773 depends on PM && NOTIFIER_ERROR_INJECTION 1774 default m if PM_DEBUG 1775 help 1776 This option provides the ability to inject artificial errors to 1777 PM notifier chain callbacks. It is controlled through debugfs 1778 interface /sys/kernel/debug/notifier-error-inject/pm 1779 1780 If the notifier call chain should be failed with some events 1781 notified, write the error code to "actions/<notifier event>/error". 1782 1783 Example: Inject PM suspend error (-12 = -ENOMEM) 1784 1785 # cd /sys/kernel/debug/notifier-error-inject/pm/ 1786 # echo -12 > actions/PM_SUSPEND_PREPARE/error 1787 # echo mem > /sys/power/state 1788 bash: echo: write error: Cannot allocate memory 1789 1790 To compile this code as a module, choose M here: the module will 1791 be called pm-notifier-error-inject. 1792 1793 If unsure, say N. 1794 1795config OF_RECONFIG_NOTIFIER_ERROR_INJECT 1796 tristate "OF reconfig notifier error injection module" 1797 depends on OF_DYNAMIC && NOTIFIER_ERROR_INJECTION 1798 help 1799 This option provides the ability to inject artificial errors to 1800 OF reconfig notifier chain callbacks. It is controlled 1801 through debugfs interface under 1802 /sys/kernel/debug/notifier-error-inject/OF-reconfig/ 1803 1804 If the notifier call chain should be failed with some events 1805 notified, write the error code to "actions/<notifier event>/error". 1806 1807 To compile this code as a module, choose M here: the module will 1808 be called of-reconfig-notifier-error-inject. 1809 1810 If unsure, say N. 1811 1812config NETDEV_NOTIFIER_ERROR_INJECT 1813 tristate "Netdev notifier error injection module" 1814 depends on NET && NOTIFIER_ERROR_INJECTION 1815 help 1816 This option provides the ability to inject artificial errors to 1817 netdevice notifier chain callbacks. It is controlled through debugfs 1818 interface /sys/kernel/debug/notifier-error-inject/netdev 1819 1820 If the notifier call chain should be failed with some events 1821 notified, write the error code to "actions/<notifier event>/error". 1822 1823 Example: Inject netdevice mtu change error (-22 = -EINVAL) 1824 1825 # cd /sys/kernel/debug/notifier-error-inject/netdev 1826 # echo -22 > actions/NETDEV_CHANGEMTU/error 1827 # ip link set eth0 mtu 1024 1828 RTNETLINK answers: Invalid argument 1829 1830 To compile this code as a module, choose M here: the module will 1831 be called netdev-notifier-error-inject. 1832 1833 If unsure, say N. 1834 1835config FUNCTION_ERROR_INJECTION 1836 def_bool y 1837 depends on HAVE_FUNCTION_ERROR_INJECTION && KPROBES 1838 1839config FAULT_INJECTION 1840 bool "Fault-injection framework" 1841 depends on DEBUG_KERNEL 1842 help 1843 Provide fault-injection framework. 1844 For more details, see Documentation/fault-injection/. 1845 1846config FAILSLAB 1847 bool "Fault-injection capability for kmalloc" 1848 depends on FAULT_INJECTION 1849 depends on SLAB || SLUB 1850 help 1851 Provide fault-injection capability for kmalloc. 1852 1853config FAIL_PAGE_ALLOC 1854 bool "Fault-injection capability for alloc_pages()" 1855 depends on FAULT_INJECTION 1856 help 1857 Provide fault-injection capability for alloc_pages(). 1858 1859config FAULT_INJECTION_USERCOPY 1860 bool "Fault injection capability for usercopy functions" 1861 depends on FAULT_INJECTION 1862 help 1863 Provides fault-injection capability to inject failures 1864 in usercopy functions (copy_from_user(), get_user(), ...). 1865 1866config FAIL_MAKE_REQUEST 1867 bool "Fault-injection capability for disk IO" 1868 depends on FAULT_INJECTION && BLOCK 1869 help 1870 Provide fault-injection capability for disk IO. 1871 1872config FAIL_IO_TIMEOUT 1873 bool "Fault-injection capability for faking disk interrupts" 1874 depends on FAULT_INJECTION && BLOCK 1875 help 1876 Provide fault-injection capability on end IO handling. This 1877 will make the block layer "forget" an interrupt as configured, 1878 thus exercising the error handling. 1879 1880 Only works with drivers that use the generic timeout handling, 1881 for others it wont do anything. 1882 1883config FAIL_FUTEX 1884 bool "Fault-injection capability for futexes" 1885 select DEBUG_FS 1886 depends on FAULT_INJECTION && FUTEX 1887 help 1888 Provide fault-injection capability for futexes. 1889 1890config FAULT_INJECTION_DEBUG_FS 1891 bool "Debugfs entries for fault-injection capabilities" 1892 depends on FAULT_INJECTION && SYSFS && DEBUG_FS 1893 help 1894 Enable configuration of fault-injection capabilities via debugfs. 1895 1896config FAIL_FUNCTION 1897 bool "Fault-injection capability for functions" 1898 depends on FAULT_INJECTION_DEBUG_FS && FUNCTION_ERROR_INJECTION 1899 help 1900 Provide function-based fault-injection capability. 1901 This will allow you to override a specific function with a return 1902 with given return value. As a result, function caller will see 1903 an error value and have to handle it. This is useful to test the 1904 error handling in various subsystems. 1905 1906config FAIL_MMC_REQUEST 1907 bool "Fault-injection capability for MMC IO" 1908 depends on FAULT_INJECTION_DEBUG_FS && MMC 1909 help 1910 Provide fault-injection capability for MMC IO. 1911 This will make the mmc core return data errors. This is 1912 useful to test the error handling in the mmc block device 1913 and to test how the mmc host driver handles retries from 1914 the block device. 1915 1916config FAULT_INJECTION_STACKTRACE_FILTER 1917 bool "stacktrace filter for fault-injection capabilities" 1918 depends on FAULT_INJECTION_DEBUG_FS && STACKTRACE_SUPPORT 1919 depends on !X86_64 1920 select STACKTRACE 1921 depends on FRAME_POINTER || MIPS || PPC || S390 || MICROBLAZE || ARM || ARC || X86 1922 help 1923 Provide stacktrace filter for fault-injection capabilities 1924 1925config ARCH_HAS_KCOV 1926 bool 1927 help 1928 An architecture should select this when it can successfully 1929 build and run with CONFIG_KCOV. This typically requires 1930 disabling instrumentation for some early boot code. 1931 1932config CC_HAS_SANCOV_TRACE_PC 1933 def_bool $(cc-option,-fsanitize-coverage=trace-pc) 1934 1935 1936config KCOV 1937 bool "Code coverage for fuzzing" 1938 depends on ARCH_HAS_KCOV 1939 depends on CC_HAS_SANCOV_TRACE_PC || GCC_PLUGINS 1940 select DEBUG_FS 1941 select GCC_PLUGIN_SANCOV if !CC_HAS_SANCOV_TRACE_PC 1942 help 1943 KCOV exposes kernel code coverage information in a form suitable 1944 for coverage-guided fuzzing (randomized testing). 1945 1946 If RANDOMIZE_BASE is enabled, PC values will not be stable across 1947 different machines and across reboots. If you need stable PC values, 1948 disable RANDOMIZE_BASE. 1949 1950 For more details, see Documentation/dev-tools/kcov.rst. 1951 1952config KCOV_ENABLE_COMPARISONS 1953 bool "Enable comparison operands collection by KCOV" 1954 depends on KCOV 1955 depends on $(cc-option,-fsanitize-coverage=trace-cmp) 1956 help 1957 KCOV also exposes operands of every comparison in the instrumented 1958 code along with operand sizes and PCs of the comparison instructions. 1959 These operands can be used by fuzzing engines to improve the quality 1960 of fuzzing coverage. 1961 1962config KCOV_INSTRUMENT_ALL 1963 bool "Instrument all code by default" 1964 depends on KCOV 1965 default y 1966 help 1967 If you are doing generic system call fuzzing (like e.g. syzkaller), 1968 then you will want to instrument the whole kernel and you should 1969 say y here. If you are doing more targeted fuzzing (like e.g. 1970 filesystem fuzzing with AFL) then you will want to enable coverage 1971 for more specific subsets of files, and should say n here. 1972 1973config KCOV_IRQ_AREA_SIZE 1974 hex "Size of interrupt coverage collection area in words" 1975 depends on KCOV 1976 default 0x40000 1977 help 1978 KCOV uses preallocated per-cpu areas to collect coverage from 1979 soft interrupts. This specifies the size of those areas in the 1980 number of unsigned long words. 1981 1982menuconfig RUNTIME_TESTING_MENU 1983 bool "Runtime Testing" 1984 def_bool y 1985 1986if RUNTIME_TESTING_MENU 1987 1988config LKDTM 1989 tristate "Linux Kernel Dump Test Tool Module" 1990 depends on DEBUG_FS 1991 help 1992 This module enables testing of the different dumping mechanisms by 1993 inducing system failures at predefined crash points. 1994 If you don't need it: say N 1995 Choose M here to compile this code as a module. The module will be 1996 called lkdtm. 1997 1998 Documentation on how to use the module can be found in 1999 Documentation/fault-injection/provoke-crashes.rst 2000 2001config TEST_LIST_SORT 2002 tristate "Linked list sorting test" 2003 depends on DEBUG_KERNEL || m 2004 help 2005 Enable this to turn on 'list_sort()' function test. This test is 2006 executed only once during system boot (so affects only boot time), 2007 or at module load time. 2008 2009 If unsure, say N. 2010 2011config TEST_MIN_HEAP 2012 tristate "Min heap test" 2013 depends on DEBUG_KERNEL || m 2014 help 2015 Enable this to turn on min heap function tests. This test is 2016 executed only once during system boot (so affects only boot time), 2017 or at module load time. 2018 2019 If unsure, say N. 2020 2021config TEST_SORT 2022 tristate "Array-based sort test" 2023 depends on DEBUG_KERNEL || m 2024 help 2025 This option enables the self-test function of 'sort()' at boot, 2026 or at module load time. 2027 2028 If unsure, say N. 2029 2030config KPROBES_SANITY_TEST 2031 bool "Kprobes sanity tests" 2032 depends on DEBUG_KERNEL 2033 depends on KPROBES 2034 help 2035 This option provides for testing basic kprobes functionality on 2036 boot. Samples of kprobe and kretprobe are inserted and 2037 verified for functionality. 2038 2039 Say N if you are unsure. 2040 2041config BACKTRACE_SELF_TEST 2042 tristate "Self test for the backtrace code" 2043 depends on DEBUG_KERNEL 2044 help 2045 This option provides a kernel module that can be used to test 2046 the kernel stack backtrace code. This option is not useful 2047 for distributions or general kernels, but only for kernel 2048 developers working on architecture code. 2049 2050 Note that if you want to also test saved backtraces, you will 2051 have to enable STACKTRACE as well. 2052 2053 Say N if you are unsure. 2054 2055config RBTREE_TEST 2056 tristate "Red-Black tree test" 2057 depends on DEBUG_KERNEL 2058 help 2059 A benchmark measuring the performance of the rbtree library. 2060 Also includes rbtree invariant checks. 2061 2062config REED_SOLOMON_TEST 2063 tristate "Reed-Solomon library test" 2064 depends on DEBUG_KERNEL || m 2065 select REED_SOLOMON 2066 select REED_SOLOMON_ENC16 2067 select REED_SOLOMON_DEC16 2068 help 2069 This option enables the self-test function of rslib at boot, 2070 or at module load time. 2071 2072 If unsure, say N. 2073 2074config INTERVAL_TREE_TEST 2075 tristate "Interval tree test" 2076 depends on DEBUG_KERNEL 2077 select INTERVAL_TREE 2078 help 2079 A benchmark measuring the performance of the interval tree library 2080 2081config PERCPU_TEST 2082 tristate "Per cpu operations test" 2083 depends on m && DEBUG_KERNEL 2084 help 2085 Enable this option to build test module which validates per-cpu 2086 operations. 2087 2088 If unsure, say N. 2089 2090config ATOMIC64_SELFTEST 2091 tristate "Perform an atomic64_t self-test" 2092 help 2093 Enable this option to test the atomic64_t functions at boot or 2094 at module load time. 2095 2096 If unsure, say N. 2097 2098config ASYNC_RAID6_TEST 2099 tristate "Self test for hardware accelerated raid6 recovery" 2100 depends on ASYNC_RAID6_RECOV 2101 select ASYNC_MEMCPY 2102 help 2103 This is a one-shot self test that permutes through the 2104 recovery of all the possible two disk failure scenarios for a 2105 N-disk array. Recovery is performed with the asynchronous 2106 raid6 recovery routines, and will optionally use an offload 2107 engine if one is available. 2108 2109 If unsure, say N. 2110 2111config TEST_HEXDUMP 2112 tristate "Test functions located in the hexdump module at runtime" 2113 2114config TEST_STRING_HELPERS 2115 tristate "Test functions located in the string_helpers module at runtime" 2116 2117config TEST_STRSCPY 2118 tristate "Test strscpy*() family of functions at runtime" 2119 2120config TEST_KSTRTOX 2121 tristate "Test kstrto*() family of functions at runtime" 2122 2123config TEST_PRINTF 2124 tristate "Test printf() family of functions at runtime" 2125 2126config TEST_BITMAP 2127 tristate "Test bitmap_*() family of functions at runtime" 2128 help 2129 Enable this option to test the bitmap functions at boot. 2130 2131 If unsure, say N. 2132 2133config TEST_UUID 2134 tristate "Test functions located in the uuid module at runtime" 2135 2136config TEST_XARRAY 2137 tristate "Test the XArray code at runtime" 2138 2139config TEST_OVERFLOW 2140 tristate "Test check_*_overflow() functions at runtime" 2141 2142config TEST_RHASHTABLE 2143 tristate "Perform selftest on resizable hash table" 2144 help 2145 Enable this option to test the rhashtable functions at boot. 2146 2147 If unsure, say N. 2148 2149config TEST_HASH 2150 tristate "Perform selftest on hash functions" 2151 help 2152 Enable this option to test the kernel's integer (<linux/hash.h>), 2153 string (<linux/stringhash.h>), and siphash (<linux/siphash.h>) 2154 hash functions on boot (or module load). 2155 2156 This is intended to help people writing architecture-specific 2157 optimized versions. If unsure, say N. 2158 2159config TEST_IDA 2160 tristate "Perform selftest on IDA functions" 2161 2162config TEST_PARMAN 2163 tristate "Perform selftest on priority array manager" 2164 depends on PARMAN 2165 help 2166 Enable this option to test priority array manager on boot 2167 (or module load). 2168 2169 If unsure, say N. 2170 2171config TEST_IRQ_TIMINGS 2172 bool "IRQ timings selftest" 2173 depends on IRQ_TIMINGS 2174 help 2175 Enable this option to test the irq timings code on boot. 2176 2177 If unsure, say N. 2178 2179config TEST_LKM 2180 tristate "Test module loading with 'hello world' module" 2181 depends on m 2182 help 2183 This builds the "test_module" module that emits "Hello, world" 2184 on printk when loaded. It is designed to be used for basic 2185 evaluation of the module loading subsystem (for example when 2186 validating module verification). It lacks any extra dependencies, 2187 and will not normally be loaded by the system unless explicitly 2188 requested by name. 2189 2190 If unsure, say N. 2191 2192config TEST_BITOPS 2193 tristate "Test module for compilation of bitops operations" 2194 depends on m 2195 help 2196 This builds the "test_bitops" module that is much like the 2197 TEST_LKM module except that it does a basic exercise of the 2198 set/clear_bit macros and get_count_order/long to make sure there are 2199 no compiler warnings from C=1 sparse checker or -Wextra 2200 compilations. It has no dependencies and doesn't run or load unless 2201 explicitly requested by name. for example: modprobe test_bitops. 2202 2203 If unsure, say N. 2204 2205config TEST_VMALLOC 2206 tristate "Test module for stress/performance analysis of vmalloc allocator" 2207 default n 2208 depends on MMU 2209 depends on m 2210 help 2211 This builds the "test_vmalloc" module that should be used for 2212 stress and performance analysis. So, any new change for vmalloc 2213 subsystem can be evaluated from performance and stability point 2214 of view. 2215 2216 If unsure, say N. 2217 2218config TEST_USER_COPY 2219 tristate "Test user/kernel boundary protections" 2220 depends on m 2221 help 2222 This builds the "test_user_copy" module that runs sanity checks 2223 on the copy_to/from_user infrastructure, making sure basic 2224 user/kernel boundary testing is working. If it fails to load, 2225 a regression has been detected in the user/kernel memory boundary 2226 protections. 2227 2228 If unsure, say N. 2229 2230config TEST_BPF 2231 tristate "Test BPF filter functionality" 2232 depends on m && NET 2233 help 2234 This builds the "test_bpf" module that runs various test vectors 2235 against the BPF interpreter or BPF JIT compiler depending on the 2236 current setting. This is in particular useful for BPF JIT compiler 2237 development, but also to run regression tests against changes in 2238 the interpreter code. It also enables test stubs for eBPF maps and 2239 verifier used by user space verifier testsuite. 2240 2241 If unsure, say N. 2242 2243config TEST_BLACKHOLE_DEV 2244 tristate "Test blackhole netdev functionality" 2245 depends on m && NET 2246 help 2247 This builds the "test_blackhole_dev" module that validates the 2248 data path through this blackhole netdev. 2249 2250 If unsure, say N. 2251 2252config FIND_BIT_BENCHMARK 2253 tristate "Test find_bit functions" 2254 help 2255 This builds the "test_find_bit" module that measure find_*_bit() 2256 functions performance. 2257 2258 If unsure, say N. 2259 2260config TEST_FIRMWARE 2261 tristate "Test firmware loading via userspace interface" 2262 depends on FW_LOADER 2263 help 2264 This builds the "test_firmware" module that creates a userspace 2265 interface for testing firmware loading. This can be used to 2266 control the triggering of firmware loading without needing an 2267 actual firmware-using device. The contents can be rechecked by 2268 userspace. 2269 2270 If unsure, say N. 2271 2272config TEST_SYSCTL 2273 tristate "sysctl test driver" 2274 depends on PROC_SYSCTL 2275 help 2276 This builds the "test_sysctl" module. This driver enables to test the 2277 proc sysctl interfaces available to drivers safely without affecting 2278 production knobs which might alter system functionality. 2279 2280 If unsure, say N. 2281 2282config BITFIELD_KUNIT 2283 tristate "KUnit test bitfield functions at runtime" 2284 depends on KUNIT 2285 help 2286 Enable this option to test the bitfield functions at boot. 2287 2288 KUnit tests run during boot and output the results to the debug log 2289 in TAP format (http://testanything.org/). Only useful for kernel devs 2290 running the KUnit test harness, and not intended for inclusion into a 2291 production build. 2292 2293 For more information on KUnit and unit tests in general please refer 2294 to the KUnit documentation in Documentation/dev-tools/kunit/. 2295 2296 If unsure, say N. 2297 2298config RESOURCE_KUNIT_TEST 2299 tristate "KUnit test for resource API" 2300 depends on KUNIT 2301 help 2302 This builds the resource API unit test. 2303 Tests the logic of API provided by resource.c and ioport.h. 2304 For more information on KUnit and unit tests in general please refer 2305 to the KUnit documentation in Documentation/dev-tools/kunit/. 2306 2307 If unsure, say N. 2308 2309config SYSCTL_KUNIT_TEST 2310 tristate "KUnit test for sysctl" if !KUNIT_ALL_TESTS 2311 depends on KUNIT 2312 default KUNIT_ALL_TESTS 2313 help 2314 This builds the proc sysctl unit test, which runs on boot. 2315 Tests the API contract and implementation correctness of sysctl. 2316 For more information on KUnit and unit tests in general please refer 2317 to the KUnit documentation in Documentation/dev-tools/kunit/. 2318 2319 If unsure, say N. 2320 2321config LIST_KUNIT_TEST 2322 tristate "KUnit Test for Kernel Linked-list structures" if !KUNIT_ALL_TESTS 2323 depends on KUNIT 2324 default KUNIT_ALL_TESTS 2325 help 2326 This builds the linked list KUnit test suite. 2327 It tests that the API and basic functionality of the list_head type 2328 and associated macros. 2329 2330 KUnit tests run during boot and output the results to the debug log 2331 in TAP format (https://testanything.org/). Only useful for kernel devs 2332 running the KUnit test harness, and not intended for inclusion into a 2333 production build. 2334 2335 For more information on KUnit and unit tests in general please refer 2336 to the KUnit documentation in Documentation/dev-tools/kunit/. 2337 2338 If unsure, say N. 2339 2340config LINEAR_RANGES_TEST 2341 tristate "KUnit test for linear_ranges" 2342 depends on KUNIT 2343 select LINEAR_RANGES 2344 help 2345 This builds the linear_ranges unit test, which runs on boot. 2346 Tests the linear_ranges logic correctness. 2347 For more information on KUnit and unit tests in general please refer 2348 to the KUnit documentation in Documentation/dev-tools/kunit/. 2349 2350 If unsure, say N. 2351 2352config CMDLINE_KUNIT_TEST 2353 tristate "KUnit test for cmdline API" 2354 depends on KUNIT 2355 help 2356 This builds the cmdline API unit test. 2357 Tests the logic of API provided by cmdline.c. 2358 For more information on KUnit and unit tests in general please refer 2359 to the KUnit documentation in Documentation/dev-tools/kunit/. 2360 2361 If unsure, say N. 2362 2363config BITS_TEST 2364 tristate "KUnit test for bits.h" 2365 depends on KUNIT 2366 help 2367 This builds the bits unit test. 2368 Tests the logic of macros defined in bits.h. 2369 For more information on KUnit and unit tests in general please refer 2370 to the KUnit documentation in Documentation/dev-tools/kunit/. 2371 2372 If unsure, say N. 2373 2374config TEST_UDELAY 2375 tristate "udelay test driver" 2376 help 2377 This builds the "udelay_test" module that helps to make sure 2378 that udelay() is working properly. 2379 2380 If unsure, say N. 2381 2382config TEST_STATIC_KEYS 2383 tristate "Test static keys" 2384 depends on m 2385 help 2386 Test the static key interfaces. 2387 2388 If unsure, say N. 2389 2390config TEST_KMOD 2391 tristate "kmod stress tester" 2392 depends on m 2393 depends on NETDEVICES && NET_CORE && INET # for TUN 2394 depends on BLOCK 2395 select TEST_LKM 2396 select XFS_FS 2397 select TUN 2398 select BTRFS_FS 2399 help 2400 Test the kernel's module loading mechanism: kmod. kmod implements 2401 support to load modules using the Linux kernel's usermode helper. 2402 This test provides a series of tests against kmod. 2403 2404 Although technically you can either build test_kmod as a module or 2405 into the kernel we disallow building it into the kernel since 2406 it stress tests request_module() and this will very likely cause 2407 some issues by taking over precious threads available from other 2408 module load requests, ultimately this could be fatal. 2409 2410 To run tests run: 2411 2412 tools/testing/selftests/kmod/kmod.sh --help 2413 2414 If unsure, say N. 2415 2416config TEST_DEBUG_VIRTUAL 2417 tristate "Test CONFIG_DEBUG_VIRTUAL feature" 2418 depends on DEBUG_VIRTUAL 2419 help 2420 Test the kernel's ability to detect incorrect calls to 2421 virt_to_phys() done against the non-linear part of the 2422 kernel's virtual address map. 2423 2424 If unsure, say N. 2425 2426config TEST_MEMCAT_P 2427 tristate "Test memcat_p() helper function" 2428 help 2429 Test the memcat_p() helper for correctly merging two 2430 pointer arrays together. 2431 2432 If unsure, say N. 2433 2434config TEST_LIVEPATCH 2435 tristate "Test livepatching" 2436 default n 2437 depends on DYNAMIC_DEBUG 2438 depends on LIVEPATCH 2439 depends on m 2440 help 2441 Test kernel livepatching features for correctness. The tests will 2442 load test modules that will be livepatched in various scenarios. 2443 2444 To run all the livepatching tests: 2445 2446 make -C tools/testing/selftests TARGETS=livepatch run_tests 2447 2448 Alternatively, individual tests may be invoked: 2449 2450 tools/testing/selftests/livepatch/test-callbacks.sh 2451 tools/testing/selftests/livepatch/test-livepatch.sh 2452 tools/testing/selftests/livepatch/test-shadow-vars.sh 2453 2454 If unsure, say N. 2455 2456config TEST_OBJAGG 2457 tristate "Perform selftest on object aggreration manager" 2458 default n 2459 depends on OBJAGG 2460 help 2461 Enable this option to test object aggregation manager on boot 2462 (or module load). 2463 2464 2465config TEST_STACKINIT 2466 tristate "Test level of stack variable initialization" 2467 help 2468 Test if the kernel is zero-initializing stack variables and 2469 padding. Coverage is controlled by compiler flags, 2470 CONFIG_GCC_PLUGIN_STRUCTLEAK, CONFIG_GCC_PLUGIN_STRUCTLEAK_BYREF, 2471 or CONFIG_GCC_PLUGIN_STRUCTLEAK_BYREF_ALL. 2472 2473 If unsure, say N. 2474 2475config TEST_MEMINIT 2476 tristate "Test heap/page initialization" 2477 help 2478 Test if the kernel is zero-initializing heap and page allocations. 2479 This can be useful to test init_on_alloc and init_on_free features. 2480 2481 If unsure, say N. 2482 2483config TEST_HMM 2484 tristate "Test HMM (Heterogeneous Memory Management)" 2485 depends on TRANSPARENT_HUGEPAGE 2486 depends on DEVICE_PRIVATE 2487 select HMM_MIRROR 2488 select MMU_NOTIFIER 2489 help 2490 This is a pseudo device driver solely for testing HMM. 2491 Say M here if you want to build the HMM test module. 2492 Doing so will allow you to run tools/testing/selftest/vm/hmm-tests. 2493 2494 If unsure, say N. 2495 2496config TEST_FREE_PAGES 2497 tristate "Test freeing pages" 2498 help 2499 Test that a memory leak does not occur due to a race between 2500 freeing a block of pages and a speculative page reference. 2501 Loading this module is safe if your kernel has the bug fixed. 2502 If the bug is not fixed, it will leak gigabytes of memory and 2503 probably OOM your system. 2504 2505config TEST_FPU 2506 tristate "Test floating point operations in kernel space" 2507 depends on X86 && !KCOV_INSTRUMENT_ALL 2508 help 2509 Enable this option to add /sys/kernel/debug/selftest_helpers/test_fpu 2510 which will trigger a sequence of floating point operations. This is used 2511 for self-testing floating point control register setting in 2512 kernel_fpu_begin(). 2513 2514 If unsure, say N. 2515 2516endif # RUNTIME_TESTING_MENU 2517 2518config MEMTEST 2519 bool "Memtest" 2520 help 2521 This option adds a kernel parameter 'memtest', which allows memtest 2522 to be set. 2523 memtest=0, mean disabled; -- default 2524 memtest=1, mean do 1 test pattern; 2525 ... 2526 memtest=17, mean do 17 test patterns. 2527 If you are unsure how to answer this question, answer N. 2528 2529 2530 2531config HYPERV_TESTING 2532 bool "Microsoft Hyper-V driver testing" 2533 default n 2534 depends on HYPERV && DEBUG_FS 2535 help 2536 Select this option to enable Hyper-V vmbus testing. 2537 2538endmenu # "Kernel Testing and Coverage" 2539 2540source "Documentation/Kconfig" 2541 2542endmenu # Kernel hacking 2543