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 VMLINUX_MAP 453 bool "Generate vmlinux.map file when linking" 454 depends on EXPERT 455 help 456 Selecting this option will pass "-Map=vmlinux.map" to ld 457 when linking vmlinux. That file can be useful for verifying 458 and debugging magic section games, and for seeing which 459 pieces of code get eliminated with 460 CONFIG_LD_DEAD_CODE_DATA_ELIMINATION. 461 462config DEBUG_FORCE_WEAK_PER_CPU 463 bool "Force weak per-cpu definitions" 464 depends on DEBUG_KERNEL 465 help 466 s390 and alpha require percpu variables in modules to be 467 defined weak to work around addressing range issue which 468 puts the following two restrictions on percpu variable 469 definitions. 470 471 1. percpu symbols must be unique whether static or not 472 2. percpu variables can't be defined inside a function 473 474 To ensure that generic code follows the above rules, this 475 option forces all percpu variables to be defined as weak. 476 477endmenu # "Compiler options" 478 479menu "Generic Kernel Debugging Instruments" 480 481config MAGIC_SYSRQ 482 bool "Magic SysRq key" 483 depends on !UML 484 help 485 If you say Y here, you will have some control over the system even 486 if the system crashes for example during kernel debugging (e.g., you 487 will be able to flush the buffer cache to disk, reboot the system 488 immediately or dump some status information). This is accomplished 489 by pressing various keys while holding SysRq (Alt+PrintScreen). It 490 also works on a serial console (on PC hardware at least), if you 491 send a BREAK and then within 5 seconds a command keypress. The 492 keys are documented in <file:Documentation/admin-guide/sysrq.rst>. 493 Don't say Y unless you really know what this hack does. 494 495config MAGIC_SYSRQ_DEFAULT_ENABLE 496 hex "Enable magic SysRq key functions by default" 497 depends on MAGIC_SYSRQ 498 default 0x1 499 help 500 Specifies which SysRq key functions are enabled by default. 501 This may be set to 1 or 0 to enable or disable them all, or 502 to a bitmask as described in Documentation/admin-guide/sysrq.rst. 503 504config MAGIC_SYSRQ_SERIAL 505 bool "Enable magic SysRq key over serial" 506 depends on MAGIC_SYSRQ 507 default y 508 help 509 Many embedded boards have a disconnected TTL level serial which can 510 generate some garbage that can lead to spurious false sysrq detects. 511 This option allows you to decide whether you want to enable the 512 magic SysRq key. 513 514config MAGIC_SYSRQ_SERIAL_SEQUENCE 515 string "Char sequence that enables magic SysRq over serial" 516 depends on MAGIC_SYSRQ_SERIAL 517 default "" 518 help 519 Specifies a sequence of characters that can follow BREAK to enable 520 SysRq on a serial console. 521 522 If unsure, leave an empty string and the option will not be enabled. 523 524config DEBUG_FS 525 bool "Debug Filesystem" 526 help 527 debugfs is a virtual file system that kernel developers use to put 528 debugging files into. Enable this option to be able to read and 529 write to these files. 530 531 For detailed documentation on the debugfs API, see 532 Documentation/filesystems/. 533 534 If unsure, say N. 535 536choice 537 prompt "Debugfs default access" 538 depends on DEBUG_FS 539 default DEBUG_FS_ALLOW_ALL 540 help 541 This selects the default access restrictions for debugfs. 542 It can be overridden with kernel command line option 543 debugfs=[on,no-mount,off]. The restrictions apply for API access 544 and filesystem registration. 545 546config DEBUG_FS_ALLOW_ALL 547 bool "Access normal" 548 help 549 No restrictions apply. Both API and filesystem registration 550 is on. This is the normal default operation. 551 552config DEBUG_FS_DISALLOW_MOUNT 553 bool "Do not register debugfs as filesystem" 554 help 555 The API is open but filesystem is not loaded. Clients can still do 556 their work and read with debug tools that do not need 557 debugfs filesystem. 558 559config DEBUG_FS_ALLOW_NONE 560 bool "No access" 561 help 562 Access is off. Clients get -PERM when trying to create nodes in 563 debugfs tree and debugfs is not registered as a filesystem. 564 Client can then back-off or continue without debugfs access. 565 566endchoice 567 568source "lib/Kconfig.kgdb" 569source "lib/Kconfig.ubsan" 570source "lib/Kconfig.kcsan" 571 572endmenu 573 574config DEBUG_KERNEL 575 bool "Kernel debugging" 576 help 577 Say Y here if you are developing drivers or trying to debug and 578 identify kernel problems. 579 580config DEBUG_MISC 581 bool "Miscellaneous debug code" 582 default DEBUG_KERNEL 583 depends on DEBUG_KERNEL 584 help 585 Say Y here if you need to enable miscellaneous debug code that should 586 be under a more specific debug option but isn't. 587 588 589menu "Memory Debugging" 590 591source "mm/Kconfig.debug" 592 593config DEBUG_OBJECTS 594 bool "Debug object operations" 595 depends on DEBUG_KERNEL 596 help 597 If you say Y here, additional code will be inserted into the 598 kernel to track the life time of various objects and validate 599 the operations on those objects. 600 601config DEBUG_OBJECTS_SELFTEST 602 bool "Debug objects selftest" 603 depends on DEBUG_OBJECTS 604 help 605 This enables the selftest of the object debug code. 606 607config DEBUG_OBJECTS_FREE 608 bool "Debug objects in freed memory" 609 depends on DEBUG_OBJECTS 610 help 611 This enables checks whether a k/v free operation frees an area 612 which contains an object which has not been deactivated 613 properly. This can make kmalloc/kfree-intensive workloads 614 much slower. 615 616config DEBUG_OBJECTS_TIMERS 617 bool "Debug timer objects" 618 depends on DEBUG_OBJECTS 619 help 620 If you say Y here, additional code will be inserted into the 621 timer routines to track the life time of timer objects and 622 validate the timer operations. 623 624config DEBUG_OBJECTS_WORK 625 bool "Debug work objects" 626 depends on DEBUG_OBJECTS 627 help 628 If you say Y here, additional code will be inserted into the 629 work queue routines to track the life time of work objects and 630 validate the work operations. 631 632config DEBUG_OBJECTS_RCU_HEAD 633 bool "Debug RCU callbacks objects" 634 depends on DEBUG_OBJECTS 635 help 636 Enable this to turn on debugging of RCU list heads (call_rcu() usage). 637 638config DEBUG_OBJECTS_PERCPU_COUNTER 639 bool "Debug percpu counter objects" 640 depends on DEBUG_OBJECTS 641 help 642 If you say Y here, additional code will be inserted into the 643 percpu counter routines to track the life time of percpu counter 644 objects and validate the percpu counter operations. 645 646config DEBUG_OBJECTS_ENABLE_DEFAULT 647 int "debug_objects bootup default value (0-1)" 648 range 0 1 649 default "1" 650 depends on DEBUG_OBJECTS 651 help 652 Debug objects boot parameter default value 653 654config DEBUG_SLAB 655 bool "Debug slab memory allocations" 656 depends on DEBUG_KERNEL && SLAB 657 help 658 Say Y here to have the kernel do limited verification on memory 659 allocation as well as poisoning memory on free to catch use of freed 660 memory. This can make kmalloc/kfree-intensive workloads much slower. 661 662config SLUB_DEBUG_ON 663 bool "SLUB debugging on by default" 664 depends on SLUB && SLUB_DEBUG 665 default n 666 help 667 Boot with debugging on by default. SLUB boots by default with 668 the runtime debug capabilities switched off. Enabling this is 669 equivalent to specifying the "slub_debug" parameter on boot. 670 There is no support for more fine grained debug control like 671 possible with slub_debug=xxx. SLUB debugging may be switched 672 off in a kernel built with CONFIG_SLUB_DEBUG_ON by specifying 673 "slub_debug=-". 674 675config SLUB_STATS 676 default n 677 bool "Enable SLUB performance statistics" 678 depends on SLUB && SYSFS 679 help 680 SLUB statistics are useful to debug SLUBs allocation behavior in 681 order find ways to optimize the allocator. This should never be 682 enabled for production use since keeping statistics slows down 683 the allocator by a few percentage points. The slabinfo command 684 supports the determination of the most active slabs to figure 685 out which slabs are relevant to a particular load. 686 Try running: slabinfo -DA 687 688config HAVE_DEBUG_KMEMLEAK 689 bool 690 691config DEBUG_KMEMLEAK 692 bool "Kernel memory leak detector" 693 depends on DEBUG_KERNEL && HAVE_DEBUG_KMEMLEAK 694 select DEBUG_FS 695 select STACKTRACE if STACKTRACE_SUPPORT 696 select KALLSYMS 697 select CRC32 698 help 699 Say Y here if you want to enable the memory leak 700 detector. The memory allocation/freeing is traced in a way 701 similar to the Boehm's conservative garbage collector, the 702 difference being that the orphan objects are not freed but 703 only shown in /sys/kernel/debug/kmemleak. Enabling this 704 feature will introduce an overhead to memory 705 allocations. See Documentation/dev-tools/kmemleak.rst for more 706 details. 707 708 Enabling DEBUG_SLAB or SLUB_DEBUG may increase the chances 709 of finding leaks due to the slab objects poisoning. 710 711 In order to access the kmemleak file, debugfs needs to be 712 mounted (usually at /sys/kernel/debug). 713 714config DEBUG_KMEMLEAK_MEM_POOL_SIZE 715 int "Kmemleak memory pool size" 716 depends on DEBUG_KMEMLEAK 717 range 200 1000000 718 default 16000 719 help 720 Kmemleak must track all the memory allocations to avoid 721 reporting false positives. Since memory may be allocated or 722 freed before kmemleak is fully initialised, use a static pool 723 of metadata objects to track such callbacks. After kmemleak is 724 fully initialised, this memory pool acts as an emergency one 725 if slab allocations fail. 726 727config DEBUG_KMEMLEAK_TEST 728 tristate "Simple test for the kernel memory leak detector" 729 depends on DEBUG_KMEMLEAK && m 730 help 731 This option enables a module that explicitly leaks memory. 732 733 If unsure, say N. 734 735config DEBUG_KMEMLEAK_DEFAULT_OFF 736 bool "Default kmemleak to off" 737 depends on DEBUG_KMEMLEAK 738 help 739 Say Y here to disable kmemleak by default. It can then be enabled 740 on the command line via kmemleak=on. 741 742config DEBUG_KMEMLEAK_AUTO_SCAN 743 bool "Enable kmemleak auto scan thread on boot up" 744 default y 745 depends on DEBUG_KMEMLEAK 746 help 747 Depending on the cpu, kmemleak scan may be cpu intensive and can 748 stall user tasks at times. This option enables/disables automatic 749 kmemleak scan at boot up. 750 751 Say N here to disable kmemleak auto scan thread to stop automatic 752 scanning. Disabling this option disables automatic reporting of 753 memory leaks. 754 755 If unsure, say Y. 756 757config DEBUG_STACK_USAGE 758 bool "Stack utilization instrumentation" 759 depends on DEBUG_KERNEL && !IA64 760 help 761 Enables the display of the minimum amount of free stack which each 762 task has ever had available in the sysrq-T and sysrq-P debug output. 763 764 This option will slow down process creation somewhat. 765 766config SCHED_STACK_END_CHECK 767 bool "Detect stack corruption on calls to schedule()" 768 depends on DEBUG_KERNEL 769 default n 770 help 771 This option checks for a stack overrun on calls to schedule(). 772 If the stack end location is found to be over written always panic as 773 the content of the corrupted region can no longer be trusted. 774 This is to ensure no erroneous behaviour occurs which could result in 775 data corruption or a sporadic crash at a later stage once the region 776 is examined. The runtime overhead introduced is minimal. 777 778config ARCH_HAS_DEBUG_VM_PGTABLE 779 bool 780 help 781 An architecture should select this when it can successfully 782 build and run DEBUG_VM_PGTABLE. 783 784config DEBUG_VM 785 bool "Debug VM" 786 depends on DEBUG_KERNEL 787 help 788 Enable this to turn on extended checks in the virtual-memory system 789 that may impact performance. 790 791 If unsure, say N. 792 793config DEBUG_VM_VMACACHE 794 bool "Debug VMA caching" 795 depends on DEBUG_VM 796 help 797 Enable this to turn on VMA caching debug information. Doing so 798 can cause significant overhead, so only enable it in non-production 799 environments. 800 801 If unsure, say N. 802 803config DEBUG_VM_RB 804 bool "Debug VM red-black trees" 805 depends on DEBUG_VM 806 help 807 Enable VM red-black tree debugging information and extra validations. 808 809 If unsure, say N. 810 811config DEBUG_VM_PGFLAGS 812 bool "Debug page-flags operations" 813 depends on DEBUG_VM 814 help 815 Enables extra validation on page flags operations. 816 817 If unsure, say N. 818 819config DEBUG_VM_PGTABLE 820 bool "Debug arch page table for semantics compliance" 821 depends on MMU 822 depends on ARCH_HAS_DEBUG_VM_PGTABLE 823 default y if DEBUG_VM 824 help 825 This option provides a debug method which can be used to test 826 architecture page table helper functions on various platforms in 827 verifying if they comply with expected generic MM semantics. This 828 will help architecture code in making sure that any changes or 829 new additions of these helpers still conform to expected 830 semantics of the generic MM. Platforms will have to opt in for 831 this through ARCH_HAS_DEBUG_VM_PGTABLE. 832 833 If unsure, say N. 834 835config ARCH_HAS_DEBUG_VIRTUAL 836 bool 837 838config DEBUG_VIRTUAL 839 bool "Debug VM translations" 840 depends on DEBUG_KERNEL && ARCH_HAS_DEBUG_VIRTUAL 841 help 842 Enable some costly sanity checks in virtual to page code. This can 843 catch mistakes with virt_to_page() and friends. 844 845 If unsure, say N. 846 847config DEBUG_NOMMU_REGIONS 848 bool "Debug the global anon/private NOMMU mapping region tree" 849 depends on DEBUG_KERNEL && !MMU 850 help 851 This option causes the global tree of anonymous and private mapping 852 regions to be regularly checked for invalid topology. 853 854config DEBUG_MEMORY_INIT 855 bool "Debug memory initialisation" if EXPERT 856 default !EXPERT 857 help 858 Enable this for additional checks during memory initialisation. 859 The sanity checks verify aspects of the VM such as the memory model 860 and other information provided by the architecture. Verbose 861 information will be printed at KERN_DEBUG loglevel depending 862 on the mminit_loglevel= command-line option. 863 864 If unsure, say Y 865 866config MEMORY_NOTIFIER_ERROR_INJECT 867 tristate "Memory hotplug notifier error injection module" 868 depends on MEMORY_HOTPLUG_SPARSE && NOTIFIER_ERROR_INJECTION 869 help 870 This option provides the ability to inject artificial errors to 871 memory hotplug notifier chain callbacks. It is controlled through 872 debugfs interface under /sys/kernel/debug/notifier-error-inject/memory 873 874 If the notifier call chain should be failed with some events 875 notified, write the error code to "actions/<notifier event>/error". 876 877 Example: Inject memory hotplug offline error (-12 == -ENOMEM) 878 879 # cd /sys/kernel/debug/notifier-error-inject/memory 880 # echo -12 > actions/MEM_GOING_OFFLINE/error 881 # echo offline > /sys/devices/system/memory/memoryXXX/state 882 bash: echo: write error: Cannot allocate memory 883 884 To compile this code as a module, choose M here: the module will 885 be called memory-notifier-error-inject. 886 887 If unsure, say N. 888 889config DEBUG_PER_CPU_MAPS 890 bool "Debug access to per_cpu maps" 891 depends on DEBUG_KERNEL 892 depends on SMP 893 help 894 Say Y to verify that the per_cpu map being accessed has 895 been set up. This adds a fair amount of code to kernel memory 896 and decreases performance. 897 898 Say N if unsure. 899 900config DEBUG_KMAP_LOCAL 901 bool "Debug kmap_local temporary mappings" 902 depends on DEBUG_KERNEL && KMAP_LOCAL 903 help 904 This option enables additional error checking for the kmap_local 905 infrastructure. Disable for production use. 906 907config ARCH_SUPPORTS_KMAP_LOCAL_FORCE_MAP 908 bool 909 910config DEBUG_KMAP_LOCAL_FORCE_MAP 911 bool "Enforce kmap_local temporary mappings" 912 depends on DEBUG_KERNEL && ARCH_SUPPORTS_KMAP_LOCAL_FORCE_MAP 913 select KMAP_LOCAL 914 select DEBUG_KMAP_LOCAL 915 help 916 This option enforces temporary mappings through the kmap_local 917 mechanism for non-highmem pages and on non-highmem systems. 918 Disable this for production systems! 919 920config DEBUG_HIGHMEM 921 bool "Highmem debugging" 922 depends on DEBUG_KERNEL && HIGHMEM 923 select DEBUG_KMAP_LOCAL_FORCE_MAP if ARCH_SUPPORTS_KMAP_LOCAL_FORCE_MAP 924 select DEBUG_KMAP_LOCAL 925 help 926 This option enables additional error checking for high memory 927 systems. Disable for production systems. 928 929config HAVE_DEBUG_STACKOVERFLOW 930 bool 931 932config DEBUG_STACKOVERFLOW 933 bool "Check for stack overflows" 934 depends on DEBUG_KERNEL && HAVE_DEBUG_STACKOVERFLOW 935 help 936 Say Y here if you want to check for overflows of kernel, IRQ 937 and exception stacks (if your architecture uses them). This 938 option will show detailed messages if free stack space drops 939 below a certain limit. 940 941 These kinds of bugs usually occur when call-chains in the 942 kernel get too deep, especially when interrupts are 943 involved. 944 945 Use this in cases where you see apparently random memory 946 corruption, especially if it appears in 'struct thread_info' 947 948 If in doubt, say "N". 949 950source "lib/Kconfig.kasan" 951source "lib/Kconfig.kfence" 952 953endmenu # "Memory Debugging" 954 955config DEBUG_SHIRQ 956 bool "Debug shared IRQ handlers" 957 depends on DEBUG_KERNEL 958 help 959 Enable this to generate a spurious interrupt just before a shared 960 interrupt handler is deregistered (generating one when registering 961 is currently disabled). Drivers need to handle this correctly. Some 962 don't and need to be caught. 963 964menu "Debug Oops, Lockups and Hangs" 965 966config PANIC_ON_OOPS 967 bool "Panic on Oops" 968 help 969 Say Y here to enable the kernel to panic when it oopses. This 970 has the same effect as setting oops=panic on the kernel command 971 line. 972 973 This feature is useful to ensure that the kernel does not do 974 anything erroneous after an oops which could result in data 975 corruption or other issues. 976 977 Say N if unsure. 978 979config PANIC_ON_OOPS_VALUE 980 int 981 range 0 1 982 default 0 if !PANIC_ON_OOPS 983 default 1 if PANIC_ON_OOPS 984 985config PANIC_TIMEOUT 986 int "panic timeout" 987 default 0 988 help 989 Set the timeout value (in seconds) until a reboot occurs when 990 the kernel panics. If n = 0, then we wait forever. A timeout 991 value n > 0 will wait n seconds before rebooting, while a timeout 992 value n < 0 will reboot immediately. 993 994config LOCKUP_DETECTOR 995 bool 996 997config SOFTLOCKUP_DETECTOR 998 bool "Detect Soft Lockups" 999 depends on DEBUG_KERNEL && !S390 1000 select LOCKUP_DETECTOR 1001 help 1002 Say Y here to enable the kernel to act as a watchdog to detect 1003 soft lockups. 1004 1005 Softlockups are bugs that cause the kernel to loop in kernel 1006 mode for more than 20 seconds, without giving other tasks a 1007 chance to run. The current stack trace is displayed upon 1008 detection and the system will stay locked up. 1009 1010config BOOTPARAM_SOFTLOCKUP_PANIC 1011 bool "Panic (Reboot) On Soft Lockups" 1012 depends on SOFTLOCKUP_DETECTOR 1013 help 1014 Say Y here to enable the kernel to panic on "soft lockups", 1015 which are bugs that cause the kernel to loop in kernel 1016 mode for more than 20 seconds (configurable using the watchdog_thresh 1017 sysctl), without giving other tasks a chance to run. 1018 1019 The panic can be used in combination with panic_timeout, 1020 to cause the system to reboot automatically after a 1021 lockup has been detected. This feature is useful for 1022 high-availability systems that have uptime guarantees and 1023 where a lockup must be resolved ASAP. 1024 1025 Say N if unsure. 1026 1027config BOOTPARAM_SOFTLOCKUP_PANIC_VALUE 1028 int 1029 depends on SOFTLOCKUP_DETECTOR 1030 range 0 1 1031 default 0 if !BOOTPARAM_SOFTLOCKUP_PANIC 1032 default 1 if BOOTPARAM_SOFTLOCKUP_PANIC 1033 1034config HARDLOCKUP_DETECTOR_PERF 1035 bool 1036 select SOFTLOCKUP_DETECTOR 1037 1038# 1039# Enables a timestamp based low pass filter to compensate for perf based 1040# hard lockup detection which runs too fast due to turbo modes. 1041# 1042config HARDLOCKUP_CHECK_TIMESTAMP 1043 bool 1044 1045# 1046# arch/ can define HAVE_HARDLOCKUP_DETECTOR_ARCH to provide their own hard 1047# lockup detector rather than the perf based detector. 1048# 1049config HARDLOCKUP_DETECTOR 1050 bool "Detect Hard Lockups" 1051 depends on DEBUG_KERNEL && !S390 1052 depends on HAVE_HARDLOCKUP_DETECTOR_PERF || HAVE_HARDLOCKUP_DETECTOR_ARCH 1053 select LOCKUP_DETECTOR 1054 select HARDLOCKUP_DETECTOR_PERF if HAVE_HARDLOCKUP_DETECTOR_PERF 1055 select HARDLOCKUP_DETECTOR_ARCH if HAVE_HARDLOCKUP_DETECTOR_ARCH 1056 help 1057 Say Y here to enable the kernel to act as a watchdog to detect 1058 hard lockups. 1059 1060 Hardlockups are bugs that cause the CPU to loop in kernel mode 1061 for more than 10 seconds, without letting other interrupts have a 1062 chance to run. The current stack trace is displayed upon detection 1063 and the system will stay locked up. 1064 1065config BOOTPARAM_HARDLOCKUP_PANIC 1066 bool "Panic (Reboot) On Hard Lockups" 1067 depends on HARDLOCKUP_DETECTOR 1068 help 1069 Say Y here to enable the kernel to panic on "hard lockups", 1070 which are bugs that cause the kernel to loop in kernel 1071 mode with interrupts disabled for more than 10 seconds (configurable 1072 using the watchdog_thresh sysctl). 1073 1074 Say N if unsure. 1075 1076config BOOTPARAM_HARDLOCKUP_PANIC_VALUE 1077 int 1078 depends on HARDLOCKUP_DETECTOR 1079 range 0 1 1080 default 0 if !BOOTPARAM_HARDLOCKUP_PANIC 1081 default 1 if BOOTPARAM_HARDLOCKUP_PANIC 1082 1083config DETECT_HUNG_TASK 1084 bool "Detect Hung Tasks" 1085 depends on DEBUG_KERNEL 1086 default SOFTLOCKUP_DETECTOR 1087 help 1088 Say Y here to enable the kernel to detect "hung tasks", 1089 which are bugs that cause the task to be stuck in 1090 uninterruptible "D" state indefinitely. 1091 1092 When a hung task is detected, the kernel will print the 1093 current stack trace (which you should report), but the 1094 task will stay in uninterruptible state. If lockdep is 1095 enabled then all held locks will also be reported. This 1096 feature has negligible overhead. 1097 1098config DEFAULT_HUNG_TASK_TIMEOUT 1099 int "Default timeout for hung task detection (in seconds)" 1100 depends on DETECT_HUNG_TASK 1101 default 120 1102 help 1103 This option controls the default timeout (in seconds) used 1104 to determine when a task has become non-responsive and should 1105 be considered hung. 1106 1107 It can be adjusted at runtime via the kernel.hung_task_timeout_secs 1108 sysctl or by writing a value to 1109 /proc/sys/kernel/hung_task_timeout_secs. 1110 1111 A timeout of 0 disables the check. The default is two minutes. 1112 Keeping the default should be fine in most cases. 1113 1114config BOOTPARAM_HUNG_TASK_PANIC 1115 bool "Panic (Reboot) On Hung Tasks" 1116 depends on DETECT_HUNG_TASK 1117 help 1118 Say Y here to enable the kernel to panic on "hung tasks", 1119 which are bugs that cause the kernel to leave a task stuck 1120 in uninterruptible "D" state. 1121 1122 The panic can be used in combination with panic_timeout, 1123 to cause the system to reboot automatically after a 1124 hung task has been detected. This feature is useful for 1125 high-availability systems that have uptime guarantees and 1126 where a hung tasks must be resolved ASAP. 1127 1128 Say N if unsure. 1129 1130config BOOTPARAM_HUNG_TASK_PANIC_VALUE 1131 int 1132 depends on DETECT_HUNG_TASK 1133 range 0 1 1134 default 0 if !BOOTPARAM_HUNG_TASK_PANIC 1135 default 1 if BOOTPARAM_HUNG_TASK_PANIC 1136 1137config WQ_WATCHDOG 1138 bool "Detect Workqueue Stalls" 1139 depends on DEBUG_KERNEL 1140 help 1141 Say Y here to enable stall detection on workqueues. If a 1142 worker pool doesn't make forward progress on a pending work 1143 item for over a given amount of time, 30s by default, a 1144 warning message is printed along with dump of workqueue 1145 state. This can be configured through kernel parameter 1146 "workqueue.watchdog_thresh" and its sysfs counterpart. 1147 1148config TEST_LOCKUP 1149 tristate "Test module to generate lockups" 1150 depends on m 1151 help 1152 This builds the "test_lockup" module that helps to make sure 1153 that watchdogs and lockup detectors are working properly. 1154 1155 Depending on module parameters it could emulate soft or hard 1156 lockup, "hung task", or locking arbitrary lock for a long time. 1157 Also it could generate series of lockups with cooling-down periods. 1158 1159 If unsure, say N. 1160 1161endmenu # "Debug lockups and hangs" 1162 1163menu "Scheduler Debugging" 1164 1165config SCHED_DEBUG 1166 bool "Collect scheduler debugging info" 1167 depends on DEBUG_KERNEL && PROC_FS 1168 default y 1169 help 1170 If you say Y here, the /proc/sched_debug file will be provided 1171 that can help debug the scheduler. The runtime overhead of this 1172 option is minimal. 1173 1174config SCHED_INFO 1175 bool 1176 default n 1177 1178config SCHEDSTATS 1179 bool "Collect scheduler statistics" 1180 depends on DEBUG_KERNEL && PROC_FS 1181 select SCHED_INFO 1182 help 1183 If you say Y here, additional code will be inserted into the 1184 scheduler and related routines to collect statistics about 1185 scheduler behavior and provide them in /proc/schedstat. These 1186 stats may be useful for both tuning and debugging the scheduler 1187 If you aren't debugging the scheduler or trying to tune a specific 1188 application, you can say N to avoid the very slight overhead 1189 this adds. 1190 1191endmenu 1192 1193config DEBUG_TIMEKEEPING 1194 bool "Enable extra timekeeping sanity checking" 1195 help 1196 This option will enable additional timekeeping sanity checks 1197 which may be helpful when diagnosing issues where timekeeping 1198 problems are suspected. 1199 1200 This may include checks in the timekeeping hotpaths, so this 1201 option may have a (very small) performance impact to some 1202 workloads. 1203 1204 If unsure, say N. 1205 1206config DEBUG_PREEMPT 1207 bool "Debug preemptible kernel" 1208 depends on DEBUG_KERNEL && PREEMPTION && TRACE_IRQFLAGS_SUPPORT 1209 default y 1210 help 1211 If you say Y here then the kernel will use a debug variant of the 1212 commonly used smp_processor_id() function and will print warnings 1213 if kernel code uses it in a preemption-unsafe way. Also, the kernel 1214 will detect preemption count underflows. 1215 1216menu "Lock Debugging (spinlocks, mutexes, etc...)" 1217 1218config LOCK_DEBUGGING_SUPPORT 1219 bool 1220 depends on TRACE_IRQFLAGS_SUPPORT && STACKTRACE_SUPPORT && LOCKDEP_SUPPORT 1221 default y 1222 1223config PROVE_LOCKING 1224 bool "Lock debugging: prove locking correctness" 1225 depends on DEBUG_KERNEL && LOCK_DEBUGGING_SUPPORT 1226 select LOCKDEP 1227 select DEBUG_SPINLOCK 1228 select DEBUG_MUTEXES 1229 select DEBUG_RT_MUTEXES if RT_MUTEXES 1230 select DEBUG_RWSEMS 1231 select DEBUG_WW_MUTEX_SLOWPATH 1232 select DEBUG_LOCK_ALLOC 1233 select PREEMPT_COUNT if !ARCH_NO_PREEMPT 1234 select TRACE_IRQFLAGS 1235 default n 1236 help 1237 This feature enables the kernel to prove that all locking 1238 that occurs in the kernel runtime is mathematically 1239 correct: that under no circumstance could an arbitrary (and 1240 not yet triggered) combination of observed locking 1241 sequences (on an arbitrary number of CPUs, running an 1242 arbitrary number of tasks and interrupt contexts) cause a 1243 deadlock. 1244 1245 In short, this feature enables the kernel to report locking 1246 related deadlocks before they actually occur. 1247 1248 The proof does not depend on how hard and complex a 1249 deadlock scenario would be to trigger: how many 1250 participant CPUs, tasks and irq-contexts would be needed 1251 for it to trigger. The proof also does not depend on 1252 timing: if a race and a resulting deadlock is possible 1253 theoretically (no matter how unlikely the race scenario 1254 is), it will be proven so and will immediately be 1255 reported by the kernel (once the event is observed that 1256 makes the deadlock theoretically possible). 1257 1258 If a deadlock is impossible (i.e. the locking rules, as 1259 observed by the kernel, are mathematically correct), the 1260 kernel reports nothing. 1261 1262 NOTE: this feature can also be enabled for rwlocks, mutexes 1263 and rwsems - in which case all dependencies between these 1264 different locking variants are observed and mapped too, and 1265 the proof of observed correctness is also maintained for an 1266 arbitrary combination of these separate locking variants. 1267 1268 For more details, see Documentation/locking/lockdep-design.rst. 1269 1270config PROVE_RAW_LOCK_NESTING 1271 bool "Enable raw_spinlock - spinlock nesting checks" 1272 depends on PROVE_LOCKING 1273 default n 1274 help 1275 Enable the raw_spinlock vs. spinlock nesting checks which ensure 1276 that the lock nesting rules for PREEMPT_RT enabled kernels are 1277 not violated. 1278 1279 NOTE: There are known nesting problems. So if you enable this 1280 option expect lockdep splats until these problems have been fully 1281 addressed which is work in progress. This config switch allows to 1282 identify and analyze these problems. It will be removed and the 1283 check permanentely enabled once the main issues have been fixed. 1284 1285 If unsure, select N. 1286 1287config LOCK_STAT 1288 bool "Lock usage statistics" 1289 depends on DEBUG_KERNEL && LOCK_DEBUGGING_SUPPORT 1290 select LOCKDEP 1291 select DEBUG_SPINLOCK 1292 select DEBUG_MUTEXES 1293 select DEBUG_RT_MUTEXES if RT_MUTEXES 1294 select DEBUG_LOCK_ALLOC 1295 default n 1296 help 1297 This feature enables tracking lock contention points 1298 1299 For more details, see Documentation/locking/lockstat.rst 1300 1301 This also enables lock events required by "perf lock", 1302 subcommand of perf. 1303 If you want to use "perf lock", you also need to turn on 1304 CONFIG_EVENT_TRACING. 1305 1306 CONFIG_LOCK_STAT defines "contended" and "acquired" lock events. 1307 (CONFIG_LOCKDEP defines "acquire" and "release" events.) 1308 1309config DEBUG_RT_MUTEXES 1310 bool "RT Mutex debugging, deadlock detection" 1311 depends on DEBUG_KERNEL && RT_MUTEXES 1312 help 1313 This allows rt mutex semantics violations and rt mutex related 1314 deadlocks (lockups) to be detected and reported automatically. 1315 1316config DEBUG_SPINLOCK 1317 bool "Spinlock and rw-lock debugging: basic checks" 1318 depends on DEBUG_KERNEL 1319 select UNINLINE_SPIN_UNLOCK 1320 help 1321 Say Y here and build SMP to catch missing spinlock initialization 1322 and certain other kinds of spinlock errors commonly made. This is 1323 best used in conjunction with the NMI watchdog so that spinlock 1324 deadlocks are also debuggable. 1325 1326config DEBUG_MUTEXES 1327 bool "Mutex debugging: basic checks" 1328 depends on DEBUG_KERNEL 1329 help 1330 This feature allows mutex semantics violations to be detected and 1331 reported. 1332 1333config DEBUG_WW_MUTEX_SLOWPATH 1334 bool "Wait/wound mutex debugging: Slowpath testing" 1335 depends on DEBUG_KERNEL && LOCK_DEBUGGING_SUPPORT 1336 select DEBUG_LOCK_ALLOC 1337 select DEBUG_SPINLOCK 1338 select DEBUG_MUTEXES 1339 help 1340 This feature enables slowpath testing for w/w mutex users by 1341 injecting additional -EDEADLK wound/backoff cases. Together with 1342 the full mutex checks enabled with (CONFIG_PROVE_LOCKING) this 1343 will test all possible w/w mutex interface abuse with the 1344 exception of simply not acquiring all the required locks. 1345 Note that this feature can introduce significant overhead, so 1346 it really should not be enabled in a production or distro kernel, 1347 even a debug kernel. If you are a driver writer, enable it. If 1348 you are a distro, do not. 1349 1350config DEBUG_RWSEMS 1351 bool "RW Semaphore debugging: basic checks" 1352 depends on DEBUG_KERNEL 1353 help 1354 This debugging feature allows mismatched rw semaphore locks 1355 and unlocks to be detected and reported. 1356 1357config DEBUG_LOCK_ALLOC 1358 bool "Lock debugging: detect incorrect freeing of live locks" 1359 depends on DEBUG_KERNEL && LOCK_DEBUGGING_SUPPORT 1360 select DEBUG_SPINLOCK 1361 select DEBUG_MUTEXES 1362 select DEBUG_RT_MUTEXES if RT_MUTEXES 1363 select LOCKDEP 1364 help 1365 This feature will check whether any held lock (spinlock, rwlock, 1366 mutex or rwsem) is incorrectly freed by the kernel, via any of the 1367 memory-freeing routines (kfree(), kmem_cache_free(), free_pages(), 1368 vfree(), etc.), whether a live lock is incorrectly reinitialized via 1369 spin_lock_init()/mutex_init()/etc., or whether there is any lock 1370 held during task exit. 1371 1372config LOCKDEP 1373 bool 1374 depends on DEBUG_KERNEL && LOCK_DEBUGGING_SUPPORT 1375 select STACKTRACE 1376 select FRAME_POINTER if !MIPS && !PPC && !ARM && !S390 && !MICROBLAZE && !ARC && !X86 1377 select KALLSYMS 1378 select KALLSYMS_ALL 1379 1380config LOCKDEP_SMALL 1381 bool 1382 1383config DEBUG_LOCKDEP 1384 bool "Lock dependency engine debugging" 1385 depends on DEBUG_KERNEL && LOCKDEP 1386 select DEBUG_IRQFLAGS 1387 help 1388 If you say Y here, the lock dependency engine will do 1389 additional runtime checks to debug itself, at the price 1390 of more runtime overhead. 1391 1392config DEBUG_ATOMIC_SLEEP 1393 bool "Sleep inside atomic section checking" 1394 select PREEMPT_COUNT 1395 depends on DEBUG_KERNEL 1396 depends on !ARCH_NO_PREEMPT 1397 help 1398 If you say Y here, various routines which may sleep will become very 1399 noisy if they are called inside atomic sections: when a spinlock is 1400 held, inside an rcu read side critical section, inside preempt disabled 1401 sections, inside an interrupt, etc... 1402 1403config DEBUG_LOCKING_API_SELFTESTS 1404 bool "Locking API boot-time self-tests" 1405 depends on DEBUG_KERNEL 1406 help 1407 Say Y here if you want the kernel to run a short self-test during 1408 bootup. The self-test checks whether common types of locking bugs 1409 are detected by debugging mechanisms or not. (if you disable 1410 lock debugging then those bugs wont be detected of course.) 1411 The following locking APIs are covered: spinlocks, rwlocks, 1412 mutexes and rwsems. 1413 1414config LOCK_TORTURE_TEST 1415 tristate "torture tests for locking" 1416 depends on DEBUG_KERNEL 1417 select TORTURE_TEST 1418 help 1419 This option provides a kernel module that runs torture tests 1420 on kernel locking primitives. The kernel module may be built 1421 after the fact on the running kernel to be tested, if desired. 1422 1423 Say Y here if you want kernel locking-primitive torture tests 1424 to be built into the kernel. 1425 Say M if you want these torture tests to build as a module. 1426 Say N if you are unsure. 1427 1428config WW_MUTEX_SELFTEST 1429 tristate "Wait/wound mutex selftests" 1430 help 1431 This option provides a kernel module that runs tests on the 1432 on the struct ww_mutex locking API. 1433 1434 It is recommended to enable DEBUG_WW_MUTEX_SLOWPATH in conjunction 1435 with this test harness. 1436 1437 Say M if you want these self tests to build as a module. 1438 Say N if you are unsure. 1439 1440config SCF_TORTURE_TEST 1441 tristate "torture tests for smp_call_function*()" 1442 depends on DEBUG_KERNEL 1443 select TORTURE_TEST 1444 help 1445 This option provides a kernel module that runs torture tests 1446 on the smp_call_function() family of primitives. The kernel 1447 module may be built after the fact on the running kernel to 1448 be tested, if desired. 1449 1450config CSD_LOCK_WAIT_DEBUG 1451 bool "Debugging for csd_lock_wait(), called from smp_call_function*()" 1452 depends on DEBUG_KERNEL 1453 depends on 64BIT 1454 default n 1455 help 1456 This option enables debug prints when CPUs are slow to respond 1457 to the smp_call_function*() IPI wrappers. These debug prints 1458 include the IPI handler function currently executing (if any) 1459 and relevant stack traces. 1460 1461endmenu # lock debugging 1462 1463config TRACE_IRQFLAGS 1464 depends on TRACE_IRQFLAGS_SUPPORT 1465 bool 1466 help 1467 Enables hooks to interrupt enabling and disabling for 1468 either tracing or lock debugging. 1469 1470config TRACE_IRQFLAGS_NMI 1471 def_bool y 1472 depends on TRACE_IRQFLAGS 1473 depends on TRACE_IRQFLAGS_NMI_SUPPORT 1474 1475config DEBUG_IRQFLAGS 1476 bool "Debug IRQ flag manipulation" 1477 help 1478 Enables checks for potentially unsafe enabling or disabling of 1479 interrupts, such as calling raw_local_irq_restore() when interrupts 1480 are enabled. 1481 1482config STACKTRACE 1483 bool "Stack backtrace support" 1484 depends on STACKTRACE_SUPPORT 1485 help 1486 This option causes the kernel to create a /proc/pid/stack for 1487 every process, showing its current stack trace. 1488 It is also used by various kernel debugging features that require 1489 stack trace generation. 1490 1491config WARN_ALL_UNSEEDED_RANDOM 1492 bool "Warn for all uses of unseeded randomness" 1493 default n 1494 help 1495 Some parts of the kernel contain bugs relating to their use of 1496 cryptographically secure random numbers before it's actually possible 1497 to generate those numbers securely. This setting ensures that these 1498 flaws don't go unnoticed, by enabling a message, should this ever 1499 occur. This will allow people with obscure setups to know when things 1500 are going wrong, so that they might contact developers about fixing 1501 it. 1502 1503 Unfortunately, on some models of some architectures getting 1504 a fully seeded CRNG is extremely difficult, and so this can 1505 result in dmesg getting spammed for a surprisingly long 1506 time. This is really bad from a security perspective, and 1507 so architecture maintainers really need to do what they can 1508 to get the CRNG seeded sooner after the system is booted. 1509 However, since users cannot do anything actionable to 1510 address this, by default the kernel will issue only a single 1511 warning for the first use of unseeded randomness. 1512 1513 Say Y here if you want to receive warnings for all uses of 1514 unseeded randomness. This will be of use primarily for 1515 those developers interested in improving the security of 1516 Linux kernels running on their architecture (or 1517 subarchitecture). 1518 1519config DEBUG_KOBJECT 1520 bool "kobject debugging" 1521 depends on DEBUG_KERNEL 1522 help 1523 If you say Y here, some extra kobject debugging messages will be sent 1524 to the syslog. 1525 1526config DEBUG_KOBJECT_RELEASE 1527 bool "kobject release debugging" 1528 depends on DEBUG_OBJECTS_TIMERS 1529 help 1530 kobjects are reference counted objects. This means that their 1531 last reference count put is not predictable, and the kobject can 1532 live on past the point at which a driver decides to drop it's 1533 initial reference to the kobject gained on allocation. An 1534 example of this would be a struct device which has just been 1535 unregistered. 1536 1537 However, some buggy drivers assume that after such an operation, 1538 the memory backing the kobject can be immediately freed. This 1539 goes completely against the principles of a refcounted object. 1540 1541 If you say Y here, the kernel will delay the release of kobjects 1542 on the last reference count to improve the visibility of this 1543 kind of kobject release bug. 1544 1545config HAVE_DEBUG_BUGVERBOSE 1546 bool 1547 1548menu "Debug kernel data structures" 1549 1550config DEBUG_LIST 1551 bool "Debug linked list manipulation" 1552 depends on DEBUG_KERNEL || BUG_ON_DATA_CORRUPTION 1553 help 1554 Enable this to turn on extended checks in the linked-list 1555 walking routines. 1556 1557 If unsure, say N. 1558 1559config DEBUG_PLIST 1560 bool "Debug priority linked list manipulation" 1561 depends on DEBUG_KERNEL 1562 help 1563 Enable this to turn on extended checks in the priority-ordered 1564 linked-list (plist) walking routines. This checks the entire 1565 list multiple times during each manipulation. 1566 1567 If unsure, say N. 1568 1569config DEBUG_SG 1570 bool "Debug SG table operations" 1571 depends on DEBUG_KERNEL 1572 help 1573 Enable this to turn on checks on scatter-gather tables. This can 1574 help find problems with drivers that do not properly initialize 1575 their sg tables. 1576 1577 If unsure, say N. 1578 1579config DEBUG_NOTIFIERS 1580 bool "Debug notifier call chains" 1581 depends on DEBUG_KERNEL 1582 help 1583 Enable this to turn on sanity checking for notifier call chains. 1584 This is most useful for kernel developers to make sure that 1585 modules properly unregister themselves from notifier chains. 1586 This is a relatively cheap check but if you care about maximum 1587 performance, say N. 1588 1589config BUG_ON_DATA_CORRUPTION 1590 bool "Trigger a BUG when data corruption is detected" 1591 select DEBUG_LIST 1592 help 1593 Select this option if the kernel should BUG when it encounters 1594 data corruption in kernel memory structures when they get checked 1595 for validity. 1596 1597 If unsure, say N. 1598 1599endmenu 1600 1601config DEBUG_CREDENTIALS 1602 bool "Debug credential management" 1603 depends on DEBUG_KERNEL 1604 help 1605 Enable this to turn on some debug checking for credential 1606 management. The additional code keeps track of the number of 1607 pointers from task_structs to any given cred struct, and checks to 1608 see that this number never exceeds the usage count of the cred 1609 struct. 1610 1611 Furthermore, if SELinux is enabled, this also checks that the 1612 security pointer in the cred struct is never seen to be invalid. 1613 1614 If unsure, say N. 1615 1616source "kernel/rcu/Kconfig.debug" 1617 1618config DEBUG_WQ_FORCE_RR_CPU 1619 bool "Force round-robin CPU selection for unbound work items" 1620 depends on DEBUG_KERNEL 1621 default n 1622 help 1623 Workqueue used to implicitly guarantee that work items queued 1624 without explicit CPU specified are put on the local CPU. This 1625 guarantee is no longer true and while local CPU is still 1626 preferred work items may be put on foreign CPUs. Kernel 1627 parameter "workqueue.debug_force_rr_cpu" is added to force 1628 round-robin CPU selection to flush out usages which depend on the 1629 now broken guarantee. This config option enables the debug 1630 feature by default. When enabled, memory and cache locality will 1631 be impacted. 1632 1633config DEBUG_BLOCK_EXT_DEVT 1634 bool "Force extended block device numbers and spread them" 1635 depends on DEBUG_KERNEL 1636 depends on BLOCK 1637 default n 1638 help 1639 BIG FAT WARNING: ENABLING THIS OPTION MIGHT BREAK BOOTING ON 1640 SOME DISTRIBUTIONS. DO NOT ENABLE THIS UNLESS YOU KNOW WHAT 1641 YOU ARE DOING. Distros, please enable this and fix whatever 1642 is broken. 1643 1644 Conventionally, block device numbers are allocated from 1645 predetermined contiguous area. However, extended block area 1646 may introduce non-contiguous block device numbers. This 1647 option forces most block device numbers to be allocated from 1648 the extended space and spreads them to discover kernel or 1649 userland code paths which assume predetermined contiguous 1650 device number allocation. 1651 1652 Note that turning on this debug option shuffles all the 1653 device numbers for all IDE and SCSI devices including libata 1654 ones, so root partition specified using device number 1655 directly (via rdev or root=MAJ:MIN) won't work anymore. 1656 Textual device names (root=/dev/sdXn) will continue to work. 1657 1658 Say N if you are unsure. 1659 1660config CPU_HOTPLUG_STATE_CONTROL 1661 bool "Enable CPU hotplug state control" 1662 depends on DEBUG_KERNEL 1663 depends on HOTPLUG_CPU 1664 default n 1665 help 1666 Allows to write steps between "offline" and "online" to the CPUs 1667 sysfs target file so states can be stepped granular. This is a debug 1668 option for now as the hotplug machinery cannot be stopped and 1669 restarted at arbitrary points yet. 1670 1671 Say N if your are unsure. 1672 1673config LATENCYTOP 1674 bool "Latency measuring infrastructure" 1675 depends on DEBUG_KERNEL 1676 depends on STACKTRACE_SUPPORT 1677 depends on PROC_FS 1678 select FRAME_POINTER if !MIPS && !PPC && !S390 && !MICROBLAZE && !ARM && !ARC && !X86 1679 select KALLSYMS 1680 select KALLSYMS_ALL 1681 select STACKTRACE 1682 select SCHEDSTATS 1683 select SCHED_DEBUG 1684 help 1685 Enable this option if you want to use the LatencyTOP tool 1686 to find out which userspace is blocking on what kernel operations. 1687 1688source "kernel/trace/Kconfig" 1689 1690config PROVIDE_OHCI1394_DMA_INIT 1691 bool "Remote debugging over FireWire early on boot" 1692 depends on PCI && X86 1693 help 1694 If you want to debug problems which hang or crash the kernel early 1695 on boot and the crashing machine has a FireWire port, you can use 1696 this feature to remotely access the memory of the crashed machine 1697 over FireWire. This employs remote DMA as part of the OHCI1394 1698 specification which is now the standard for FireWire controllers. 1699 1700 With remote DMA, you can monitor the printk buffer remotely using 1701 firescope and access all memory below 4GB using fireproxy from gdb. 1702 Even controlling a kernel debugger is possible using remote DMA. 1703 1704 Usage: 1705 1706 If ohci1394_dma=early is used as boot parameter, it will initialize 1707 all OHCI1394 controllers which are found in the PCI config space. 1708 1709 As all changes to the FireWire bus such as enabling and disabling 1710 devices cause a bus reset and thereby disable remote DMA for all 1711 devices, be sure to have the cable plugged and FireWire enabled on 1712 the debugging host before booting the debug target for debugging. 1713 1714 This code (~1k) is freed after boot. By then, the firewire stack 1715 in charge of the OHCI-1394 controllers should be used instead. 1716 1717 See Documentation/core-api/debugging-via-ohci1394.rst for more information. 1718 1719source "samples/Kconfig" 1720 1721config ARCH_HAS_DEVMEM_IS_ALLOWED 1722 bool 1723 1724config STRICT_DEVMEM 1725 bool "Filter access to /dev/mem" 1726 depends on MMU && DEVMEM 1727 depends on ARCH_HAS_DEVMEM_IS_ALLOWED || GENERIC_LIB_DEVMEM_IS_ALLOWED 1728 default y if PPC || X86 || ARM64 1729 help 1730 If this option is disabled, you allow userspace (root) access to all 1731 of memory, including kernel and userspace memory. Accidental 1732 access to this is obviously disastrous, but specific access can 1733 be used by people debugging the kernel. Note that with PAT support 1734 enabled, even in this case there are restrictions on /dev/mem 1735 use due to the cache aliasing requirements. 1736 1737 If this option is switched on, and IO_STRICT_DEVMEM=n, the /dev/mem 1738 file only allows userspace access to PCI space and the BIOS code and 1739 data regions. This is sufficient for dosemu and X and all common 1740 users of /dev/mem. 1741 1742 If in doubt, say Y. 1743 1744config IO_STRICT_DEVMEM 1745 bool "Filter I/O access to /dev/mem" 1746 depends on STRICT_DEVMEM 1747 help 1748 If this option is disabled, you allow userspace (root) access to all 1749 io-memory regardless of whether a driver is actively using that 1750 range. Accidental access to this is obviously disastrous, but 1751 specific access can be used by people debugging kernel drivers. 1752 1753 If this option is switched on, the /dev/mem file only allows 1754 userspace access to *idle* io-memory ranges (see /proc/iomem) This 1755 may break traditional users of /dev/mem (dosemu, legacy X, etc...) 1756 if the driver using a given range cannot be disabled. 1757 1758 If in doubt, say Y. 1759 1760menu "$(SRCARCH) Debugging" 1761 1762source "arch/$(SRCARCH)/Kconfig.debug" 1763 1764endmenu 1765 1766menu "Kernel Testing and Coverage" 1767 1768source "lib/kunit/Kconfig" 1769 1770config NOTIFIER_ERROR_INJECTION 1771 tristate "Notifier error injection" 1772 depends on DEBUG_KERNEL 1773 select DEBUG_FS 1774 help 1775 This option provides the ability to inject artificial errors to 1776 specified notifier chain callbacks. It is useful to test the error 1777 handling of notifier call chain failures. 1778 1779 Say N if unsure. 1780 1781config PM_NOTIFIER_ERROR_INJECT 1782 tristate "PM notifier error injection module" 1783 depends on PM && NOTIFIER_ERROR_INJECTION 1784 default m if PM_DEBUG 1785 help 1786 This option provides the ability to inject artificial errors to 1787 PM notifier chain callbacks. It is controlled through debugfs 1788 interface /sys/kernel/debug/notifier-error-inject/pm 1789 1790 If the notifier call chain should be failed with some events 1791 notified, write the error code to "actions/<notifier event>/error". 1792 1793 Example: Inject PM suspend error (-12 = -ENOMEM) 1794 1795 # cd /sys/kernel/debug/notifier-error-inject/pm/ 1796 # echo -12 > actions/PM_SUSPEND_PREPARE/error 1797 # echo mem > /sys/power/state 1798 bash: echo: write error: Cannot allocate memory 1799 1800 To compile this code as a module, choose M here: the module will 1801 be called pm-notifier-error-inject. 1802 1803 If unsure, say N. 1804 1805config OF_RECONFIG_NOTIFIER_ERROR_INJECT 1806 tristate "OF reconfig notifier error injection module" 1807 depends on OF_DYNAMIC && NOTIFIER_ERROR_INJECTION 1808 help 1809 This option provides the ability to inject artificial errors to 1810 OF reconfig notifier chain callbacks. It is controlled 1811 through debugfs interface under 1812 /sys/kernel/debug/notifier-error-inject/OF-reconfig/ 1813 1814 If the notifier call chain should be failed with some events 1815 notified, write the error code to "actions/<notifier event>/error". 1816 1817 To compile this code as a module, choose M here: the module will 1818 be called of-reconfig-notifier-error-inject. 1819 1820 If unsure, say N. 1821 1822config NETDEV_NOTIFIER_ERROR_INJECT 1823 tristate "Netdev notifier error injection module" 1824 depends on NET && NOTIFIER_ERROR_INJECTION 1825 help 1826 This option provides the ability to inject artificial errors to 1827 netdevice notifier chain callbacks. It is controlled through debugfs 1828 interface /sys/kernel/debug/notifier-error-inject/netdev 1829 1830 If the notifier call chain should be failed with some events 1831 notified, write the error code to "actions/<notifier event>/error". 1832 1833 Example: Inject netdevice mtu change error (-22 = -EINVAL) 1834 1835 # cd /sys/kernel/debug/notifier-error-inject/netdev 1836 # echo -22 > actions/NETDEV_CHANGEMTU/error 1837 # ip link set eth0 mtu 1024 1838 RTNETLINK answers: Invalid argument 1839 1840 To compile this code as a module, choose M here: the module will 1841 be called netdev-notifier-error-inject. 1842 1843 If unsure, say N. 1844 1845config FUNCTION_ERROR_INJECTION 1846 def_bool y 1847 depends on HAVE_FUNCTION_ERROR_INJECTION && KPROBES 1848 1849config FAULT_INJECTION 1850 bool "Fault-injection framework" 1851 depends on DEBUG_KERNEL 1852 help 1853 Provide fault-injection framework. 1854 For more details, see Documentation/fault-injection/. 1855 1856config FAILSLAB 1857 bool "Fault-injection capability for kmalloc" 1858 depends on FAULT_INJECTION 1859 depends on SLAB || SLUB 1860 help 1861 Provide fault-injection capability for kmalloc. 1862 1863config FAIL_PAGE_ALLOC 1864 bool "Fault-injection capability for alloc_pages()" 1865 depends on FAULT_INJECTION 1866 help 1867 Provide fault-injection capability for alloc_pages(). 1868 1869config FAULT_INJECTION_USERCOPY 1870 bool "Fault injection capability for usercopy functions" 1871 depends on FAULT_INJECTION 1872 help 1873 Provides fault-injection capability to inject failures 1874 in usercopy functions (copy_from_user(), get_user(), ...). 1875 1876config FAIL_MAKE_REQUEST 1877 bool "Fault-injection capability for disk IO" 1878 depends on FAULT_INJECTION && BLOCK 1879 help 1880 Provide fault-injection capability for disk IO. 1881 1882config FAIL_IO_TIMEOUT 1883 bool "Fault-injection capability for faking disk interrupts" 1884 depends on FAULT_INJECTION && BLOCK 1885 help 1886 Provide fault-injection capability on end IO handling. This 1887 will make the block layer "forget" an interrupt as configured, 1888 thus exercising the error handling. 1889 1890 Only works with drivers that use the generic timeout handling, 1891 for others it wont do anything. 1892 1893config FAIL_FUTEX 1894 bool "Fault-injection capability for futexes" 1895 select DEBUG_FS 1896 depends on FAULT_INJECTION && FUTEX 1897 help 1898 Provide fault-injection capability for futexes. 1899 1900config FAULT_INJECTION_DEBUG_FS 1901 bool "Debugfs entries for fault-injection capabilities" 1902 depends on FAULT_INJECTION && SYSFS && DEBUG_FS 1903 help 1904 Enable configuration of fault-injection capabilities via debugfs. 1905 1906config FAIL_FUNCTION 1907 bool "Fault-injection capability for functions" 1908 depends on FAULT_INJECTION_DEBUG_FS && FUNCTION_ERROR_INJECTION 1909 help 1910 Provide function-based fault-injection capability. 1911 This will allow you to override a specific function with a return 1912 with given return value. As a result, function caller will see 1913 an error value and have to handle it. This is useful to test the 1914 error handling in various subsystems. 1915 1916config FAIL_MMC_REQUEST 1917 bool "Fault-injection capability for MMC IO" 1918 depends on FAULT_INJECTION_DEBUG_FS && MMC 1919 help 1920 Provide fault-injection capability for MMC IO. 1921 This will make the mmc core return data errors. This is 1922 useful to test the error handling in the mmc block device 1923 and to test how the mmc host driver handles retries from 1924 the block device. 1925 1926config FAULT_INJECTION_STACKTRACE_FILTER 1927 bool "stacktrace filter for fault-injection capabilities" 1928 depends on FAULT_INJECTION_DEBUG_FS && STACKTRACE_SUPPORT 1929 depends on !X86_64 1930 select STACKTRACE 1931 select FRAME_POINTER if !MIPS && !PPC && !S390 && !MICROBLAZE && !ARM && !ARC && !X86 1932 help 1933 Provide stacktrace filter for fault-injection capabilities 1934 1935config ARCH_HAS_KCOV 1936 bool 1937 help 1938 An architecture should select this when it can successfully 1939 build and run with CONFIG_KCOV. This typically requires 1940 disabling instrumentation for some early boot code. 1941 1942config CC_HAS_SANCOV_TRACE_PC 1943 def_bool $(cc-option,-fsanitize-coverage=trace-pc) 1944 1945 1946config KCOV 1947 bool "Code coverage for fuzzing" 1948 depends on ARCH_HAS_KCOV 1949 depends on CC_HAS_SANCOV_TRACE_PC || GCC_PLUGINS 1950 select DEBUG_FS 1951 select GCC_PLUGIN_SANCOV if !CC_HAS_SANCOV_TRACE_PC 1952 help 1953 KCOV exposes kernel code coverage information in a form suitable 1954 for coverage-guided fuzzing (randomized testing). 1955 1956 If RANDOMIZE_BASE is enabled, PC values will not be stable across 1957 different machines and across reboots. If you need stable PC values, 1958 disable RANDOMIZE_BASE. 1959 1960 For more details, see Documentation/dev-tools/kcov.rst. 1961 1962config KCOV_ENABLE_COMPARISONS 1963 bool "Enable comparison operands collection by KCOV" 1964 depends on KCOV 1965 depends on $(cc-option,-fsanitize-coverage=trace-cmp) 1966 help 1967 KCOV also exposes operands of every comparison in the instrumented 1968 code along with operand sizes and PCs of the comparison instructions. 1969 These operands can be used by fuzzing engines to improve the quality 1970 of fuzzing coverage. 1971 1972config KCOV_INSTRUMENT_ALL 1973 bool "Instrument all code by default" 1974 depends on KCOV 1975 default y 1976 help 1977 If you are doing generic system call fuzzing (like e.g. syzkaller), 1978 then you will want to instrument the whole kernel and you should 1979 say y here. If you are doing more targeted fuzzing (like e.g. 1980 filesystem fuzzing with AFL) then you will want to enable coverage 1981 for more specific subsets of files, and should say n here. 1982 1983config KCOV_IRQ_AREA_SIZE 1984 hex "Size of interrupt coverage collection area in words" 1985 depends on KCOV 1986 default 0x40000 1987 help 1988 KCOV uses preallocated per-cpu areas to collect coverage from 1989 soft interrupts. This specifies the size of those areas in the 1990 number of unsigned long words. 1991 1992menuconfig RUNTIME_TESTING_MENU 1993 bool "Runtime Testing" 1994 def_bool y 1995 1996if RUNTIME_TESTING_MENU 1997 1998config LKDTM 1999 tristate "Linux Kernel Dump Test Tool Module" 2000 depends on DEBUG_FS 2001 help 2002 This module enables testing of the different dumping mechanisms by 2003 inducing system failures at predefined crash points. 2004 If you don't need it: say N 2005 Choose M here to compile this code as a module. The module will be 2006 called lkdtm. 2007 2008 Documentation on how to use the module can be found in 2009 Documentation/fault-injection/provoke-crashes.rst 2010 2011config TEST_LIST_SORT 2012 tristate "Linked list sorting test" 2013 depends on DEBUG_KERNEL || m 2014 help 2015 Enable this to turn on 'list_sort()' function test. 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_MIN_HEAP 2022 tristate "Min heap test" 2023 depends on DEBUG_KERNEL || m 2024 help 2025 Enable this to turn on min heap function tests. This test is 2026 executed only once during system boot (so affects only boot time), 2027 or at module load time. 2028 2029 If unsure, say N. 2030 2031config TEST_SORT 2032 tristate "Array-based sort test" 2033 depends on DEBUG_KERNEL || m 2034 help 2035 This option enables the self-test function of 'sort()' at boot, 2036 or at module load time. 2037 2038 If unsure, say N. 2039 2040config KPROBES_SANITY_TEST 2041 bool "Kprobes sanity tests" 2042 depends on DEBUG_KERNEL 2043 depends on KPROBES 2044 help 2045 This option provides for testing basic kprobes functionality on 2046 boot. Samples of kprobe and kretprobe are inserted and 2047 verified for functionality. 2048 2049 Say N if you are unsure. 2050 2051config BACKTRACE_SELF_TEST 2052 tristate "Self test for the backtrace code" 2053 depends on DEBUG_KERNEL 2054 help 2055 This option provides a kernel module that can be used to test 2056 the kernel stack backtrace code. This option is not useful 2057 for distributions or general kernels, but only for kernel 2058 developers working on architecture code. 2059 2060 Note that if you want to also test saved backtraces, you will 2061 have to enable STACKTRACE as well. 2062 2063 Say N if you are unsure. 2064 2065config RBTREE_TEST 2066 tristate "Red-Black tree test" 2067 depends on DEBUG_KERNEL 2068 help 2069 A benchmark measuring the performance of the rbtree library. 2070 Also includes rbtree invariant checks. 2071 2072config REED_SOLOMON_TEST 2073 tristate "Reed-Solomon library test" 2074 depends on DEBUG_KERNEL || m 2075 select REED_SOLOMON 2076 select REED_SOLOMON_ENC16 2077 select REED_SOLOMON_DEC16 2078 help 2079 This option enables the self-test function of rslib at boot, 2080 or at module load time. 2081 2082 If unsure, say N. 2083 2084config INTERVAL_TREE_TEST 2085 tristate "Interval tree test" 2086 depends on DEBUG_KERNEL 2087 select INTERVAL_TREE 2088 help 2089 A benchmark measuring the performance of the interval tree library 2090 2091config PERCPU_TEST 2092 tristate "Per cpu operations test" 2093 depends on m && DEBUG_KERNEL 2094 help 2095 Enable this option to build test module which validates per-cpu 2096 operations. 2097 2098 If unsure, say N. 2099 2100config ATOMIC64_SELFTEST 2101 tristate "Perform an atomic64_t self-test" 2102 help 2103 Enable this option to test the atomic64_t functions at boot or 2104 at module load time. 2105 2106 If unsure, say N. 2107 2108config ASYNC_RAID6_TEST 2109 tristate "Self test for hardware accelerated raid6 recovery" 2110 depends on ASYNC_RAID6_RECOV 2111 select ASYNC_MEMCPY 2112 help 2113 This is a one-shot self test that permutes through the 2114 recovery of all the possible two disk failure scenarios for a 2115 N-disk array. Recovery is performed with the asynchronous 2116 raid6 recovery routines, and will optionally use an offload 2117 engine if one is available. 2118 2119 If unsure, say N. 2120 2121config TEST_HEXDUMP 2122 tristate "Test functions located in the hexdump module at runtime" 2123 2124config TEST_STRING_HELPERS 2125 tristate "Test functions located in the string_helpers module at runtime" 2126 2127config TEST_STRSCPY 2128 tristate "Test strscpy*() family of functions at runtime" 2129 2130config TEST_KSTRTOX 2131 tristate "Test kstrto*() family of functions at runtime" 2132 2133config TEST_PRINTF 2134 tristate "Test printf() family of functions at runtime" 2135 2136config TEST_BITMAP 2137 tristate "Test bitmap_*() family of functions at runtime" 2138 help 2139 Enable this option to test the bitmap functions at boot. 2140 2141 If unsure, say N. 2142 2143config TEST_UUID 2144 tristate "Test functions located in the uuid module at runtime" 2145 2146config TEST_XARRAY 2147 tristate "Test the XArray code at runtime" 2148 2149config TEST_OVERFLOW 2150 tristate "Test check_*_overflow() functions at runtime" 2151 2152config TEST_RHASHTABLE 2153 tristate "Perform selftest on resizable hash table" 2154 help 2155 Enable this option to test the rhashtable functions at boot. 2156 2157 If unsure, say N. 2158 2159config TEST_HASH 2160 tristate "Perform selftest on hash functions" 2161 help 2162 Enable this option to test the kernel's integer (<linux/hash.h>), 2163 string (<linux/stringhash.h>), and siphash (<linux/siphash.h>) 2164 hash functions on boot (or module load). 2165 2166 This is intended to help people writing architecture-specific 2167 optimized versions. If unsure, say N. 2168 2169config TEST_IDA 2170 tristate "Perform selftest on IDA functions" 2171 2172config TEST_PARMAN 2173 tristate "Perform selftest on priority array manager" 2174 depends on PARMAN 2175 help 2176 Enable this option to test priority array manager on boot 2177 (or module load). 2178 2179 If unsure, say N. 2180 2181config TEST_IRQ_TIMINGS 2182 bool "IRQ timings selftest" 2183 depends on IRQ_TIMINGS 2184 help 2185 Enable this option to test the irq timings code on boot. 2186 2187 If unsure, say N. 2188 2189config TEST_LKM 2190 tristate "Test module loading with 'hello world' module" 2191 depends on m 2192 help 2193 This builds the "test_module" module that emits "Hello, world" 2194 on printk when loaded. It is designed to be used for basic 2195 evaluation of the module loading subsystem (for example when 2196 validating module verification). It lacks any extra dependencies, 2197 and will not normally be loaded by the system unless explicitly 2198 requested by name. 2199 2200 If unsure, say N. 2201 2202config TEST_BITOPS 2203 tristate "Test module for compilation of bitops operations" 2204 depends on m 2205 help 2206 This builds the "test_bitops" module that is much like the 2207 TEST_LKM module except that it does a basic exercise of the 2208 set/clear_bit macros and get_count_order/long to make sure there are 2209 no compiler warnings from C=1 sparse checker or -Wextra 2210 compilations. It has no dependencies and doesn't run or load unless 2211 explicitly requested by name. for example: modprobe test_bitops. 2212 2213 If unsure, say N. 2214 2215config TEST_VMALLOC 2216 tristate "Test module for stress/performance analysis of vmalloc allocator" 2217 default n 2218 depends on MMU 2219 depends on m 2220 help 2221 This builds the "test_vmalloc" module that should be used for 2222 stress and performance analysis. So, any new change for vmalloc 2223 subsystem can be evaluated from performance and stability point 2224 of view. 2225 2226 If unsure, say N. 2227 2228config TEST_USER_COPY 2229 tristate "Test user/kernel boundary protections" 2230 depends on m 2231 help 2232 This builds the "test_user_copy" module that runs sanity checks 2233 on the copy_to/from_user infrastructure, making sure basic 2234 user/kernel boundary testing is working. If it fails to load, 2235 a regression has been detected in the user/kernel memory boundary 2236 protections. 2237 2238 If unsure, say N. 2239 2240config TEST_BPF 2241 tristate "Test BPF filter functionality" 2242 depends on m && NET 2243 help 2244 This builds the "test_bpf" module that runs various test vectors 2245 against the BPF interpreter or BPF JIT compiler depending on the 2246 current setting. This is in particular useful for BPF JIT compiler 2247 development, but also to run regression tests against changes in 2248 the interpreter code. It also enables test stubs for eBPF maps and 2249 verifier used by user space verifier testsuite. 2250 2251 If unsure, say N. 2252 2253config TEST_BLACKHOLE_DEV 2254 tristate "Test blackhole netdev functionality" 2255 depends on m && NET 2256 help 2257 This builds the "test_blackhole_dev" module that validates the 2258 data path through this blackhole netdev. 2259 2260 If unsure, say N. 2261 2262config FIND_BIT_BENCHMARK 2263 tristate "Test find_bit functions" 2264 help 2265 This builds the "test_find_bit" module that measure find_*_bit() 2266 functions performance. 2267 2268 If unsure, say N. 2269 2270config TEST_FIRMWARE 2271 tristate "Test firmware loading via userspace interface" 2272 depends on FW_LOADER 2273 help 2274 This builds the "test_firmware" module that creates a userspace 2275 interface for testing firmware loading. This can be used to 2276 control the triggering of firmware loading without needing an 2277 actual firmware-using device. The contents can be rechecked by 2278 userspace. 2279 2280 If unsure, say N. 2281 2282config TEST_SYSCTL 2283 tristate "sysctl test driver" 2284 depends on PROC_SYSCTL 2285 help 2286 This builds the "test_sysctl" module. This driver enables to test the 2287 proc sysctl interfaces available to drivers safely without affecting 2288 production knobs which might alter system functionality. 2289 2290 If unsure, say N. 2291 2292config BITFIELD_KUNIT 2293 tristate "KUnit test bitfield functions at runtime" 2294 depends on KUNIT 2295 help 2296 Enable this option to test the bitfield functions at boot. 2297 2298 KUnit tests run during boot and output the results to the debug log 2299 in TAP format (http://testanything.org/). Only useful for kernel devs 2300 running the KUnit test harness, and not intended for inclusion into a 2301 production build. 2302 2303 For more information on KUnit and unit tests in general please refer 2304 to the KUnit documentation in Documentation/dev-tools/kunit/. 2305 2306 If unsure, say N. 2307 2308config RESOURCE_KUNIT_TEST 2309 tristate "KUnit test for resource API" 2310 depends on KUNIT 2311 help 2312 This builds the resource API unit test. 2313 Tests the logic of API provided by resource.c and ioport.h. 2314 For more information on KUnit and unit tests in general please refer 2315 to the KUnit documentation in Documentation/dev-tools/kunit/. 2316 2317 If unsure, say N. 2318 2319config SYSCTL_KUNIT_TEST 2320 tristate "KUnit test for sysctl" if !KUNIT_ALL_TESTS 2321 depends on KUNIT 2322 default KUNIT_ALL_TESTS 2323 help 2324 This builds the proc sysctl unit test, which runs on boot. 2325 Tests the API contract and implementation correctness of sysctl. 2326 For more information on KUnit and unit tests in general please refer 2327 to the KUnit documentation in Documentation/dev-tools/kunit/. 2328 2329 If unsure, say N. 2330 2331config LIST_KUNIT_TEST 2332 tristate "KUnit Test for Kernel Linked-list structures" if !KUNIT_ALL_TESTS 2333 depends on KUNIT 2334 default KUNIT_ALL_TESTS 2335 help 2336 This builds the linked list KUnit test suite. 2337 It tests that the API and basic functionality of the list_head type 2338 and associated macros. 2339 2340 KUnit tests run during boot and output the results to the debug log 2341 in TAP format (https://testanything.org/). Only useful for kernel devs 2342 running the KUnit test harness, and not intended for inclusion into a 2343 production build. 2344 2345 For more information on KUnit and unit tests in general please refer 2346 to the KUnit documentation in Documentation/dev-tools/kunit/. 2347 2348 If unsure, say N. 2349 2350config LINEAR_RANGES_TEST 2351 tristate "KUnit test for linear_ranges" 2352 depends on KUNIT 2353 select LINEAR_RANGES 2354 help 2355 This builds the linear_ranges unit test, which runs on boot. 2356 Tests the linear_ranges logic correctness. 2357 For more information on KUnit and unit tests in general please refer 2358 to the KUnit documentation in Documentation/dev-tools/kunit/. 2359 2360 If unsure, say N. 2361 2362config CMDLINE_KUNIT_TEST 2363 tristate "KUnit test for cmdline API" 2364 depends on KUNIT 2365 help 2366 This builds the cmdline API unit test. 2367 Tests the logic of API provided by cmdline.c. 2368 For more information on KUnit and unit tests in general please refer 2369 to the KUnit documentation in Documentation/dev-tools/kunit/. 2370 2371 If unsure, say N. 2372 2373config BITS_TEST 2374 tristate "KUnit test for bits.h" 2375 depends on KUNIT 2376 help 2377 This builds the bits unit test. 2378 Tests the logic of macros defined in bits.h. 2379 For more information on KUnit and unit tests in general please refer 2380 to the KUnit documentation in Documentation/dev-tools/kunit/. 2381 2382 If unsure, say N. 2383 2384config TEST_UDELAY 2385 tristate "udelay test driver" 2386 help 2387 This builds the "udelay_test" module that helps to make sure 2388 that udelay() is working properly. 2389 2390 If unsure, say N. 2391 2392config TEST_STATIC_KEYS 2393 tristate "Test static keys" 2394 depends on m 2395 help 2396 Test the static key interfaces. 2397 2398 If unsure, say N. 2399 2400config TEST_KMOD 2401 tristate "kmod stress tester" 2402 depends on m 2403 depends on NETDEVICES && NET_CORE && INET # for TUN 2404 depends on BLOCK 2405 select TEST_LKM 2406 select XFS_FS 2407 select TUN 2408 select BTRFS_FS 2409 help 2410 Test the kernel's module loading mechanism: kmod. kmod implements 2411 support to load modules using the Linux kernel's usermode helper. 2412 This test provides a series of tests against kmod. 2413 2414 Although technically you can either build test_kmod as a module or 2415 into the kernel we disallow building it into the kernel since 2416 it stress tests request_module() and this will very likely cause 2417 some issues by taking over precious threads available from other 2418 module load requests, ultimately this could be fatal. 2419 2420 To run tests run: 2421 2422 tools/testing/selftests/kmod/kmod.sh --help 2423 2424 If unsure, say N. 2425 2426config TEST_DEBUG_VIRTUAL 2427 tristate "Test CONFIG_DEBUG_VIRTUAL feature" 2428 depends on DEBUG_VIRTUAL 2429 help 2430 Test the kernel's ability to detect incorrect calls to 2431 virt_to_phys() done against the non-linear part of the 2432 kernel's virtual address map. 2433 2434 If unsure, say N. 2435 2436config TEST_MEMCAT_P 2437 tristate "Test memcat_p() helper function" 2438 help 2439 Test the memcat_p() helper for correctly merging two 2440 pointer arrays together. 2441 2442 If unsure, say N. 2443 2444config TEST_LIVEPATCH 2445 tristate "Test livepatching" 2446 default n 2447 depends on DYNAMIC_DEBUG 2448 depends on LIVEPATCH 2449 depends on m 2450 help 2451 Test kernel livepatching features for correctness. The tests will 2452 load test modules that will be livepatched in various scenarios. 2453 2454 To run all the livepatching tests: 2455 2456 make -C tools/testing/selftests TARGETS=livepatch run_tests 2457 2458 Alternatively, individual tests may be invoked: 2459 2460 tools/testing/selftests/livepatch/test-callbacks.sh 2461 tools/testing/selftests/livepatch/test-livepatch.sh 2462 tools/testing/selftests/livepatch/test-shadow-vars.sh 2463 2464 If unsure, say N. 2465 2466config TEST_OBJAGG 2467 tristate "Perform selftest on object aggreration manager" 2468 default n 2469 depends on OBJAGG 2470 help 2471 Enable this option to test object aggregation manager on boot 2472 (or module load). 2473 2474 2475config TEST_STACKINIT 2476 tristate "Test level of stack variable initialization" 2477 help 2478 Test if the kernel is zero-initializing stack variables and 2479 padding. Coverage is controlled by compiler flags, 2480 CONFIG_GCC_PLUGIN_STRUCTLEAK, CONFIG_GCC_PLUGIN_STRUCTLEAK_BYREF, 2481 or CONFIG_GCC_PLUGIN_STRUCTLEAK_BYREF_ALL. 2482 2483 If unsure, say N. 2484 2485config TEST_MEMINIT 2486 tristate "Test heap/page initialization" 2487 help 2488 Test if the kernel is zero-initializing heap and page allocations. 2489 This can be useful to test init_on_alloc and init_on_free features. 2490 2491 If unsure, say N. 2492 2493config TEST_HMM 2494 tristate "Test HMM (Heterogeneous Memory Management)" 2495 depends on TRANSPARENT_HUGEPAGE 2496 depends on DEVICE_PRIVATE 2497 select HMM_MIRROR 2498 select MMU_NOTIFIER 2499 help 2500 This is a pseudo device driver solely for testing HMM. 2501 Say M here if you want to build the HMM test module. 2502 Doing so will allow you to run tools/testing/selftest/vm/hmm-tests. 2503 2504 If unsure, say N. 2505 2506config TEST_FREE_PAGES 2507 tristate "Test freeing pages" 2508 help 2509 Test that a memory leak does not occur due to a race between 2510 freeing a block of pages and a speculative page reference. 2511 Loading this module is safe if your kernel has the bug fixed. 2512 If the bug is not fixed, it will leak gigabytes of memory and 2513 probably OOM your system. 2514 2515config TEST_FPU 2516 tristate "Test floating point operations in kernel space" 2517 depends on X86 && !KCOV_INSTRUMENT_ALL 2518 help 2519 Enable this option to add /sys/kernel/debug/selftest_helpers/test_fpu 2520 which will trigger a sequence of floating point operations. This is used 2521 for self-testing floating point control register setting in 2522 kernel_fpu_begin(). 2523 2524 If unsure, say N. 2525 2526endif # RUNTIME_TESTING_MENU 2527 2528config MEMTEST 2529 bool "Memtest" 2530 help 2531 This option adds a kernel parameter 'memtest', which allows memtest 2532 to be set. 2533 memtest=0, mean disabled; -- default 2534 memtest=1, mean do 1 test pattern; 2535 ... 2536 memtest=17, mean do 17 test patterns. 2537 If you are unsure how to answer this question, answer N. 2538 2539 2540 2541config HYPERV_TESTING 2542 bool "Microsoft Hyper-V driver testing" 2543 default n 2544 depends on HYPERV && DEBUG_FS 2545 help 2546 Select this option to enable Hyper-V vmbus testing. 2547 2548endmenu # "Kernel Testing and Coverage" 2549 2550source "Documentation/Kconfig" 2551 2552endmenu # Kernel hacking 2553