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 STACKTRACE_BUILD_ID 39 bool "Show build ID information in stacktraces" 40 depends on PRINTK 41 help 42 Selecting this option adds build ID information for symbols in 43 stacktraces printed with the printk format '%p[SR]b'. 44 45 This option is intended for distros where debuginfo is not easily 46 accessible but can be downloaded given the build ID of the vmlinux or 47 kernel module where the function is located. 48 49config CONSOLE_LOGLEVEL_DEFAULT 50 int "Default console loglevel (1-15)" 51 range 1 15 52 default "7" 53 help 54 Default loglevel to determine what will be printed on the console. 55 56 Setting a default here is equivalent to passing in loglevel=<x> in 57 the kernel bootargs. loglevel=<x> continues to override whatever 58 value is specified here as well. 59 60 Note: This does not affect the log level of un-prefixed printk() 61 usage in the kernel. That is controlled by the MESSAGE_LOGLEVEL_DEFAULT 62 option. 63 64config CONSOLE_LOGLEVEL_QUIET 65 int "quiet console loglevel (1-15)" 66 range 1 15 67 default "4" 68 help 69 loglevel to use when "quiet" is passed on the kernel commandline. 70 71 When "quiet" is passed on the kernel commandline this loglevel 72 will be used as the loglevel. IOW passing "quiet" will be the 73 equivalent of passing "loglevel=<CONSOLE_LOGLEVEL_QUIET>" 74 75config MESSAGE_LOGLEVEL_DEFAULT 76 int "Default message log level (1-7)" 77 range 1 7 78 default "4" 79 help 80 Default log level for printk statements with no specified priority. 81 82 This was hard-coded to KERN_WARNING since at least 2.6.10 but folks 83 that are auditing their logs closely may want to set it to a lower 84 priority. 85 86 Note: This does not affect what message level gets printed on the console 87 by default. To change that, use loglevel=<x> in the kernel bootargs, 88 or pick a different CONSOLE_LOGLEVEL_DEFAULT configuration value. 89 90config BOOT_PRINTK_DELAY 91 bool "Delay each boot printk message by N milliseconds" 92 depends on DEBUG_KERNEL && PRINTK && GENERIC_CALIBRATE_DELAY 93 help 94 This build option allows you to read kernel boot messages 95 by inserting a short delay after each one. The delay is 96 specified in milliseconds on the kernel command line, 97 using "boot_delay=N". 98 99 It is likely that you would also need to use "lpj=M" to preset 100 the "loops per jiffie" value. 101 See a previous boot log for the "lpj" value to use for your 102 system, and then set "lpj=M" before setting "boot_delay=N". 103 NOTE: Using this option may adversely affect SMP systems. 104 I.e., processors other than the first one may not boot up. 105 BOOT_PRINTK_DELAY also may cause LOCKUP_DETECTOR to detect 106 what it believes to be lockup conditions. 107 108config DYNAMIC_DEBUG 109 bool "Enable dynamic printk() support" 110 default n 111 depends on PRINTK 112 depends on (DEBUG_FS || PROC_FS) 113 select DYNAMIC_DEBUG_CORE 114 help 115 116 Compiles debug level messages into the kernel, which would not 117 otherwise be available at runtime. These messages can then be 118 enabled/disabled based on various levels of scope - per source file, 119 function, module, format string, and line number. This mechanism 120 implicitly compiles in all pr_debug() and dev_dbg() calls, which 121 enlarges the kernel text size by about 2%. 122 123 If a source file is compiled with DEBUG flag set, any 124 pr_debug() calls in it are enabled by default, but can be 125 disabled at runtime as below. Note that DEBUG flag is 126 turned on by many CONFIG_*DEBUG* options. 127 128 Usage: 129 130 Dynamic debugging is controlled via the 'dynamic_debug/control' file, 131 which is contained in the 'debugfs' filesystem or procfs. 132 Thus, the debugfs or procfs filesystem must first be mounted before 133 making use of this feature. 134 We refer the control file as: <debugfs>/dynamic_debug/control. This 135 file contains a list of the debug statements that can be enabled. The 136 format for each line of the file is: 137 138 filename:lineno [module]function flags format 139 140 filename : source file of the debug statement 141 lineno : line number of the debug statement 142 module : module that contains the debug statement 143 function : function that contains the debug statement 144 flags : '=p' means the line is turned 'on' for printing 145 format : the format used for the debug statement 146 147 From a live system: 148 149 nullarbor:~ # cat <debugfs>/dynamic_debug/control 150 # filename:lineno [module]function flags format 151 fs/aio.c:222 [aio]__put_ioctx =_ "__put_ioctx:\040freeing\040%p\012" 152 fs/aio.c:248 [aio]ioctx_alloc =_ "ENOMEM:\040nr_events\040too\040high\012" 153 fs/aio.c:1770 [aio]sys_io_cancel =_ "calling\040cancel\012" 154 155 Example usage: 156 157 // enable the message at line 1603 of file svcsock.c 158 nullarbor:~ # echo -n 'file svcsock.c line 1603 +p' > 159 <debugfs>/dynamic_debug/control 160 161 // enable all the messages in file svcsock.c 162 nullarbor:~ # echo -n 'file svcsock.c +p' > 163 <debugfs>/dynamic_debug/control 164 165 // enable all the messages in the NFS server module 166 nullarbor:~ # echo -n 'module nfsd +p' > 167 <debugfs>/dynamic_debug/control 168 169 // enable all 12 messages in the function svc_process() 170 nullarbor:~ # echo -n 'func svc_process +p' > 171 <debugfs>/dynamic_debug/control 172 173 // disable all 12 messages in the function svc_process() 174 nullarbor:~ # echo -n 'func svc_process -p' > 175 <debugfs>/dynamic_debug/control 176 177 See Documentation/admin-guide/dynamic-debug-howto.rst for additional 178 information. 179 180config DYNAMIC_DEBUG_CORE 181 bool "Enable core function of dynamic debug support" 182 depends on PRINTK 183 depends on (DEBUG_FS || PROC_FS) 184 help 185 Enable core functional support of dynamic debug. It is useful 186 when you want to tie dynamic debug to your kernel modules with 187 DYNAMIC_DEBUG_MODULE defined for each of them, especially for 188 the case of embedded system where the kernel image size is 189 sensitive for people. 190 191config SYMBOLIC_ERRNAME 192 bool "Support symbolic error names in printf" 193 default y if PRINTK 194 help 195 If you say Y here, the kernel's printf implementation will 196 be able to print symbolic error names such as ENOSPC instead 197 of the number 28. It makes the kernel image slightly larger 198 (about 3KB), but can make the kernel logs easier to read. 199 200config DEBUG_BUGVERBOSE 201 bool "Verbose BUG() reporting (adds 70K)" if DEBUG_KERNEL && EXPERT 202 depends on BUG && (GENERIC_BUG || HAVE_DEBUG_BUGVERBOSE) 203 default y 204 help 205 Say Y here to make BUG() panics output the file name and line number 206 of the BUG call as well as the EIP and oops trace. This aids 207 debugging but costs about 70-100K of memory. 208 209endmenu # "printk and dmesg options" 210 211config DEBUG_KERNEL 212 bool "Kernel debugging" 213 help 214 Say Y here if you are developing drivers or trying to debug and 215 identify kernel problems. 216 217config DEBUG_MISC 218 bool "Miscellaneous debug code" 219 default DEBUG_KERNEL 220 depends on DEBUG_KERNEL 221 help 222 Say Y here if you need to enable miscellaneous debug code that should 223 be under a more specific debug option but isn't. 224 225menu "Compile-time checks and compiler options" 226 227config DEBUG_INFO 228 bool 229 help 230 A kernel debug info option other than "None" has been selected 231 in the "Debug information" choice below, indicating that debug 232 information will be generated for build targets. 233 234# Clang is known to generate .{s,u}leb128 with symbol deltas with DWARF5, which 235# some targets may not support: https://sourceware.org/bugzilla/show_bug.cgi?id=27215 236config AS_HAS_NON_CONST_LEB128 237 def_bool $(as-instr,.uleb128 .Lexpr_end4 - .Lexpr_start3\n.Lexpr_start3:\n.Lexpr_end4:) 238 239choice 240 prompt "Debug information" 241 depends on DEBUG_KERNEL 242 help 243 Selecting something other than "None" results in a kernel image 244 that will include debugging info resulting in a larger kernel image. 245 This adds debug symbols to the kernel and modules (gcc -g), and 246 is needed if you intend to use kernel crashdump or binary object 247 tools like crash, kgdb, LKCD, gdb, etc on the kernel. 248 249 Choose which version of DWARF debug info to emit. If unsure, 250 select "Toolchain default". 251 252config DEBUG_INFO_NONE 253 bool "Disable debug information" 254 help 255 Do not build the kernel with debugging information, which will 256 result in a faster and smaller build. 257 258config DEBUG_INFO_DWARF_TOOLCHAIN_DEFAULT 259 bool "Rely on the toolchain's implicit default DWARF version" 260 select DEBUG_INFO 261 depends on !CC_IS_CLANG || AS_IS_LLVM || CLANG_VERSION < 140000 || (AS_IS_GNU && AS_VERSION >= 23502 && AS_HAS_NON_CONST_LEB128) 262 help 263 The implicit default version of DWARF debug info produced by a 264 toolchain changes over time. 265 266 This can break consumers of the debug info that haven't upgraded to 267 support newer revisions, and prevent testing newer versions, but 268 those should be less common scenarios. 269 270config DEBUG_INFO_DWARF4 271 bool "Generate DWARF Version 4 debuginfo" 272 select DEBUG_INFO 273 depends on !CC_IS_CLANG || AS_IS_LLVM || (AS_IS_GNU && AS_VERSION >= 23502) 274 help 275 Generate DWARF v4 debug info. This requires gcc 4.5+, binutils 2.35.2 276 if using clang without clang's integrated assembler, and gdb 7.0+. 277 278 If you have consumers of DWARF debug info that are not ready for 279 newer revisions of DWARF, you may wish to choose this or have your 280 config select this. 281 282config DEBUG_INFO_DWARF5 283 bool "Generate DWARF Version 5 debuginfo" 284 select DEBUG_INFO 285 depends on !CC_IS_CLANG || AS_IS_LLVM || (AS_IS_GNU && AS_VERSION >= 23502 && AS_HAS_NON_CONST_LEB128) 286 help 287 Generate DWARF v5 debug info. Requires binutils 2.35.2, gcc 5.0+ (gcc 288 5.0+ accepts the -gdwarf-5 flag but only had partial support for some 289 draft features until 7.0), and gdb 8.0+. 290 291 Changes to the structure of debug info in Version 5 allow for around 292 15-18% savings in resulting image and debug info section sizes as 293 compared to DWARF Version 4. DWARF Version 5 standardizes previous 294 extensions such as accelerators for symbol indexing and the format 295 for fission (.dwo/.dwp) files. Users may not want to select this 296 config if they rely on tooling that has not yet been updated to 297 support DWARF Version 5. 298 299endchoice # "Debug information" 300 301if DEBUG_INFO 302 303config DEBUG_INFO_REDUCED 304 bool "Reduce debugging information" 305 help 306 If you say Y here gcc is instructed to generate less debugging 307 information for structure types. This means that tools that 308 need full debugging information (like kgdb or systemtap) won't 309 be happy. But if you merely need debugging information to 310 resolve line numbers there is no loss. Advantage is that 311 build directory object sizes shrink dramatically over a full 312 DEBUG_INFO build and compile times are reduced too. 313 Only works with newer gcc versions. 314 315choice 316 prompt "Compressed Debug information" 317 help 318 Compress the resulting debug info. Results in smaller debug info sections, 319 but requires that consumers are able to decompress the results. 320 321 If unsure, choose DEBUG_INFO_COMPRESSED_NONE. 322 323config DEBUG_INFO_COMPRESSED_NONE 324 bool "Don't compress debug information" 325 help 326 Don't compress debug info sections. 327 328config DEBUG_INFO_COMPRESSED_ZLIB 329 bool "Compress debugging information with zlib" 330 depends on $(cc-option,-gz=zlib) 331 depends on $(ld-option,--compress-debug-sections=zlib) 332 help 333 Compress the debug information using zlib. Requires GCC 5.0+ or Clang 334 5.0+, binutils 2.26+, and zlib. 335 336 Users of dpkg-deb via scripts/package/builddeb may find an increase in 337 size of their debug .deb packages with this config set, due to the 338 debug info being compressed with zlib, then the object files being 339 recompressed with a different compression scheme. But this is still 340 preferable to setting $KDEB_COMPRESS to "none" which would be even 341 larger. 342 343config DEBUG_INFO_COMPRESSED_ZSTD 344 bool "Compress debugging information with zstd" 345 depends on $(cc-option,-gz=zstd) 346 depends on $(ld-option,--compress-debug-sections=zstd) 347 help 348 Compress the debug information using zstd. This may provide better 349 compression than zlib, for about the same time costs, but requires newer 350 toolchain support. Requires GCC 13.0+ or Clang 16.0+, binutils 2.40+, and 351 zstd. 352 353endchoice # "Compressed Debug information" 354 355config DEBUG_INFO_SPLIT 356 bool "Produce split debuginfo in .dwo files" 357 depends on $(cc-option,-gsplit-dwarf) 358 help 359 Generate debug info into separate .dwo files. This significantly 360 reduces the build directory size for builds with DEBUG_INFO, 361 because it stores the information only once on disk in .dwo 362 files instead of multiple times in object files and executables. 363 In addition the debug information is also compressed. 364 365 Requires recent gcc (4.7+) and recent gdb/binutils. 366 Any tool that packages or reads debug information would need 367 to know about the .dwo files and include them. 368 Incompatible with older versions of ccache. 369 370config DEBUG_INFO_BTF 371 bool "Generate BTF typeinfo" 372 depends on !DEBUG_INFO_SPLIT && !DEBUG_INFO_REDUCED 373 depends on !GCC_PLUGIN_RANDSTRUCT || COMPILE_TEST 374 depends on BPF_SYSCALL 375 depends on !DEBUG_INFO_DWARF5 || PAHOLE_VERSION >= 121 376 help 377 Generate deduplicated BTF type information from DWARF debug info. 378 Turning this on expects presence of pahole tool, which will convert 379 DWARF type info into equivalent deduplicated BTF type info. 380 381config PAHOLE_HAS_SPLIT_BTF 382 def_bool PAHOLE_VERSION >= 119 383 384config PAHOLE_HAS_BTF_TAG 385 def_bool PAHOLE_VERSION >= 123 386 depends on CC_IS_CLANG 387 help 388 Decide whether pahole emits btf_tag attributes (btf_type_tag and 389 btf_decl_tag) or not. Currently only clang compiler implements 390 these attributes, so make the config depend on CC_IS_CLANG. 391 392config PAHOLE_HAS_LANG_EXCLUDE 393 def_bool PAHOLE_VERSION >= 124 394 help 395 Support for the --lang_exclude flag which makes pahole exclude 396 compilation units from the supplied language. Used in Kbuild to 397 omit Rust CUs which are not supported in version 1.24 of pahole, 398 otherwise it would emit malformed kernel and module binaries when 399 using DEBUG_INFO_BTF_MODULES. 400 401config DEBUG_INFO_BTF_MODULES 402 def_bool y 403 depends on DEBUG_INFO_BTF && MODULES && PAHOLE_HAS_SPLIT_BTF 404 help 405 Generate compact split BTF type information for kernel modules. 406 407config MODULE_ALLOW_BTF_MISMATCH 408 bool "Allow loading modules with non-matching BTF type info" 409 depends on DEBUG_INFO_BTF_MODULES 410 help 411 For modules whose split BTF does not match vmlinux, load without 412 BTF rather than refusing to load. The default behavior with 413 module BTF enabled is to reject modules with such mismatches; 414 this option will still load module BTF where possible but ignore 415 it when a mismatch is found. 416 417config GDB_SCRIPTS 418 bool "Provide GDB scripts for kernel debugging" 419 help 420 This creates the required links to GDB helper scripts in the 421 build directory. If you load vmlinux into gdb, the helper 422 scripts will be automatically imported by gdb as well, and 423 additional functions are available to analyze a Linux kernel 424 instance. See Documentation/dev-tools/gdb-kernel-debugging.rst 425 for further details. 426 427endif # DEBUG_INFO 428 429config FRAME_WARN 430 int "Warn for stack frames larger than" 431 range 0 8192 432 default 0 if KMSAN 433 default 2048 if GCC_PLUGIN_LATENT_ENTROPY 434 default 2048 if PARISC 435 default 1536 if (!64BIT && XTENSA) 436 default 1280 if KASAN && !64BIT 437 default 1024 if !64BIT 438 default 2048 if 64BIT 439 help 440 Tell the compiler to warn at build time for stack frames larger than this. 441 Setting this too low will cause a lot of warnings. 442 Setting it to 0 disables the warning. 443 444config STRIP_ASM_SYMS 445 bool "Strip assembler-generated symbols during link" 446 default n 447 help 448 Strip internal assembler-generated symbols during a link (symbols 449 that look like '.Lxxx') so they don't pollute the output of 450 get_wchan() and suchlike. 451 452config READABLE_ASM 453 bool "Generate readable assembler code" 454 depends on DEBUG_KERNEL 455 depends on CC_IS_GCC 456 help 457 Disable some compiler optimizations that tend to generate human unreadable 458 assembler output. This may make the kernel slightly slower, but it helps 459 to keep kernel developers who have to stare a lot at assembler listings 460 sane. 461 462config HEADERS_INSTALL 463 bool "Install uapi headers to usr/include" 464 depends on !UML 465 help 466 This option will install uapi headers (headers exported to user-space) 467 into the usr/include directory for use during the kernel build. 468 This is unneeded for building the kernel itself, but needed for some 469 user-space program samples. It is also needed by some features such 470 as uapi header sanity checks. 471 472config DEBUG_SECTION_MISMATCH 473 bool "Enable full Section mismatch analysis" 474 depends on CC_IS_GCC 475 help 476 The section mismatch analysis checks if there are illegal 477 references from one section to another section. 478 During linktime or runtime, some sections are dropped; 479 any use of code/data previously in these sections would 480 most likely result in an oops. 481 In the code, functions and variables are annotated with 482 __init,, etc. (see the full list in include/linux/init.h), 483 which results in the code/data being placed in specific sections. 484 The section mismatch analysis is always performed after a full 485 kernel build, and enabling this option causes the following 486 additional step to occur: 487 - Add the option -fno-inline-functions-called-once to gcc commands. 488 When inlining a function annotated with __init in a non-init 489 function, we would lose the section information and thus 490 the analysis would not catch the illegal reference. 491 This option tells gcc to inline less (but it does result in 492 a larger kernel). 493 494config SECTION_MISMATCH_WARN_ONLY 495 bool "Make section mismatch errors non-fatal" 496 default y 497 help 498 If you say N here, the build process will fail if there are any 499 section mismatch, instead of just throwing warnings. 500 501 If unsure, say Y. 502 503config DEBUG_FORCE_FUNCTION_ALIGN_64B 504 bool "Force all function address 64B aligned" 505 depends on EXPERT && (X86_64 || ARM64 || PPC32 || PPC64 || ARC) 506 select FUNCTION_ALIGNMENT_64B 507 help 508 There are cases that a commit from one domain changes the function 509 address alignment of other domains, and cause magic performance 510 bump (regression or improvement). Enable this option will help to 511 verify if the bump is caused by function alignment changes, while 512 it will slightly increase the kernel size and affect icache usage. 513 514 It is mainly for debug and performance tuning use. 515 516# 517# Select this config option from the architecture Kconfig, if it 518# is preferred to always offer frame pointers as a config 519# option on the architecture (regardless of KERNEL_DEBUG): 520# 521config ARCH_WANT_FRAME_POINTERS 522 bool 523 524config FRAME_POINTER 525 bool "Compile the kernel with frame pointers" 526 depends on DEBUG_KERNEL && (M68K || UML || SUPERH) || ARCH_WANT_FRAME_POINTERS 527 default y if (DEBUG_INFO && UML) || ARCH_WANT_FRAME_POINTERS 528 help 529 If you say Y here the resulting kernel image will be slightly 530 larger and slower, but it gives very useful debugging information 531 in case of kernel bugs. (precise oopses/stacktraces/warnings) 532 533config OBJTOOL 534 bool 535 536config STACK_VALIDATION 537 bool "Compile-time stack metadata validation" 538 depends on HAVE_STACK_VALIDATION && UNWINDER_FRAME_POINTER 539 select OBJTOOL 540 default n 541 help 542 Validate frame pointer rules at compile-time. This helps ensure that 543 runtime stack traces are more reliable. 544 545 For more information, see 546 tools/objtool/Documentation/objtool.txt. 547 548config NOINSTR_VALIDATION 549 bool 550 depends on HAVE_NOINSTR_VALIDATION && DEBUG_ENTRY 551 select OBJTOOL 552 default y 553 554config VMLINUX_MAP 555 bool "Generate vmlinux.map file when linking" 556 depends on EXPERT 557 help 558 Selecting this option will pass "-Map=vmlinux.map" to ld 559 when linking vmlinux. That file can be useful for verifying 560 and debugging magic section games, and for seeing which 561 pieces of code get eliminated with 562 CONFIG_LD_DEAD_CODE_DATA_ELIMINATION. 563 564config DEBUG_FORCE_WEAK_PER_CPU 565 bool "Force weak per-cpu definitions" 566 depends on DEBUG_KERNEL 567 help 568 s390 and alpha require percpu variables in modules to be 569 defined weak to work around addressing range issue which 570 puts the following two restrictions on percpu variable 571 definitions. 572 573 1. percpu symbols must be unique whether static or not 574 2. percpu variables can't be defined inside a function 575 576 To ensure that generic code follows the above rules, this 577 option forces all percpu variables to be defined as weak. 578 579endmenu # "Compiler options" 580 581menu "Generic Kernel Debugging Instruments" 582 583config MAGIC_SYSRQ 584 bool "Magic SysRq key" 585 depends on !UML 586 help 587 If you say Y here, you will have some control over the system even 588 if the system crashes for example during kernel debugging (e.g., you 589 will be able to flush the buffer cache to disk, reboot the system 590 immediately or dump some status information). This is accomplished 591 by pressing various keys while holding SysRq (Alt+PrintScreen). It 592 also works on a serial console (on PC hardware at least), if you 593 send a BREAK and then within 5 seconds a command keypress. The 594 keys are documented in <file:Documentation/admin-guide/sysrq.rst>. 595 Don't say Y unless you really know what this hack does. 596 597config MAGIC_SYSRQ_DEFAULT_ENABLE 598 hex "Enable magic SysRq key functions by default" 599 depends on MAGIC_SYSRQ 600 default 0x1 601 help 602 Specifies which SysRq key functions are enabled by default. 603 This may be set to 1 or 0 to enable or disable them all, or 604 to a bitmask as described in Documentation/admin-guide/sysrq.rst. 605 606config MAGIC_SYSRQ_SERIAL 607 bool "Enable magic SysRq key over serial" 608 depends on MAGIC_SYSRQ 609 default y 610 help 611 Many embedded boards have a disconnected TTL level serial which can 612 generate some garbage that can lead to spurious false sysrq detects. 613 This option allows you to decide whether you want to enable the 614 magic SysRq key. 615 616config MAGIC_SYSRQ_SERIAL_SEQUENCE 617 string "Char sequence that enables magic SysRq over serial" 618 depends on MAGIC_SYSRQ_SERIAL 619 default "" 620 help 621 Specifies a sequence of characters that can follow BREAK to enable 622 SysRq on a serial console. 623 624 If unsure, leave an empty string and the option will not be enabled. 625 626config DEBUG_FS 627 bool "Debug Filesystem" 628 help 629 debugfs is a virtual file system that kernel developers use to put 630 debugging files into. Enable this option to be able to read and 631 write to these files. 632 633 For detailed documentation on the debugfs API, see 634 Documentation/filesystems/. 635 636 If unsure, say N. 637 638choice 639 prompt "Debugfs default access" 640 depends on DEBUG_FS 641 default DEBUG_FS_ALLOW_ALL 642 help 643 This selects the default access restrictions for debugfs. 644 It can be overridden with kernel command line option 645 debugfs=[on,no-mount,off]. The restrictions apply for API access 646 and filesystem registration. 647 648config DEBUG_FS_ALLOW_ALL 649 bool "Access normal" 650 help 651 No restrictions apply. Both API and filesystem registration 652 is on. This is the normal default operation. 653 654config DEBUG_FS_DISALLOW_MOUNT 655 bool "Do not register debugfs as filesystem" 656 help 657 The API is open but filesystem is not loaded. Clients can still do 658 their work and read with debug tools that do not need 659 debugfs filesystem. 660 661config DEBUG_FS_ALLOW_NONE 662 bool "No access" 663 help 664 Access is off. Clients get -PERM when trying to create nodes in 665 debugfs tree and debugfs is not registered as a filesystem. 666 Client can then back-off or continue without debugfs access. 667 668endchoice 669 670source "lib/Kconfig.kgdb" 671source "lib/Kconfig.ubsan" 672source "lib/Kconfig.kcsan" 673 674endmenu 675 676menu "Networking Debugging" 677 678source "net/Kconfig.debug" 679 680endmenu # "Networking Debugging" 681 682menu "Memory Debugging" 683 684source "mm/Kconfig.debug" 685 686config DEBUG_OBJECTS 687 bool "Debug object operations" 688 depends on DEBUG_KERNEL 689 help 690 If you say Y here, additional code will be inserted into the 691 kernel to track the life time of various objects and validate 692 the operations on those objects. 693 694config DEBUG_OBJECTS_SELFTEST 695 bool "Debug objects selftest" 696 depends on DEBUG_OBJECTS 697 help 698 This enables the selftest of the object debug code. 699 700config DEBUG_OBJECTS_FREE 701 bool "Debug objects in freed memory" 702 depends on DEBUG_OBJECTS 703 help 704 This enables checks whether a k/v free operation frees an area 705 which contains an object which has not been deactivated 706 properly. This can make kmalloc/kfree-intensive workloads 707 much slower. 708 709config DEBUG_OBJECTS_TIMERS 710 bool "Debug timer objects" 711 depends on DEBUG_OBJECTS 712 help 713 If you say Y here, additional code will be inserted into the 714 timer routines to track the life time of timer objects and 715 validate the timer operations. 716 717config DEBUG_OBJECTS_WORK 718 bool "Debug work objects" 719 depends on DEBUG_OBJECTS 720 help 721 If you say Y here, additional code will be inserted into the 722 work queue routines to track the life time of work objects and 723 validate the work operations. 724 725config DEBUG_OBJECTS_RCU_HEAD 726 bool "Debug RCU callbacks objects" 727 depends on DEBUG_OBJECTS 728 help 729 Enable this to turn on debugging of RCU list heads (call_rcu() usage). 730 731config DEBUG_OBJECTS_PERCPU_COUNTER 732 bool "Debug percpu counter objects" 733 depends on DEBUG_OBJECTS 734 help 735 If you say Y here, additional code will be inserted into the 736 percpu counter routines to track the life time of percpu counter 737 objects and validate the percpu counter operations. 738 739config DEBUG_OBJECTS_ENABLE_DEFAULT 740 int "debug_objects bootup default value (0-1)" 741 range 0 1 742 default "1" 743 depends on DEBUG_OBJECTS 744 help 745 Debug objects boot parameter default value 746 747config SHRINKER_DEBUG 748 bool "Enable shrinker debugging support" 749 depends on DEBUG_FS 750 help 751 Say Y to enable the shrinker debugfs interface which provides 752 visibility into the kernel memory shrinkers subsystem. 753 Disable it to avoid an extra memory footprint. 754 755config HAVE_DEBUG_KMEMLEAK 756 bool 757 758config DEBUG_KMEMLEAK 759 bool "Kernel memory leak detector" 760 depends on DEBUG_KERNEL && HAVE_DEBUG_KMEMLEAK 761 select DEBUG_FS 762 select STACKTRACE if STACKTRACE_SUPPORT 763 select KALLSYMS 764 select CRC32 765 select STACKDEPOT 766 help 767 Say Y here if you want to enable the memory leak 768 detector. The memory allocation/freeing is traced in a way 769 similar to the Boehm's conservative garbage collector, the 770 difference being that the orphan objects are not freed but 771 only shown in /sys/kernel/debug/kmemleak. Enabling this 772 feature will introduce an overhead to memory 773 allocations. See Documentation/dev-tools/kmemleak.rst for more 774 details. 775 776 Enabling DEBUG_SLAB or SLUB_DEBUG may increase the chances 777 of finding leaks due to the slab objects poisoning. 778 779 In order to access the kmemleak file, debugfs needs to be 780 mounted (usually at /sys/kernel/debug). 781 782config DEBUG_KMEMLEAK_MEM_POOL_SIZE 783 int "Kmemleak memory pool size" 784 depends on DEBUG_KMEMLEAK 785 range 200 1000000 786 default 16000 787 help 788 Kmemleak must track all the memory allocations to avoid 789 reporting false positives. Since memory may be allocated or 790 freed before kmemleak is fully initialised, use a static pool 791 of metadata objects to track such callbacks. After kmemleak is 792 fully initialised, this memory pool acts as an emergency one 793 if slab allocations fail. 794 795config DEBUG_KMEMLEAK_TEST 796 tristate "Simple test for the kernel memory leak detector" 797 depends on DEBUG_KMEMLEAK && m 798 help 799 This option enables a module that explicitly leaks memory. 800 801 If unsure, say N. 802 803config DEBUG_KMEMLEAK_DEFAULT_OFF 804 bool "Default kmemleak to off" 805 depends on DEBUG_KMEMLEAK 806 help 807 Say Y here to disable kmemleak by default. It can then be enabled 808 on the command line via kmemleak=on. 809 810config DEBUG_KMEMLEAK_AUTO_SCAN 811 bool "Enable kmemleak auto scan thread on boot up" 812 default y 813 depends on DEBUG_KMEMLEAK 814 help 815 Depending on the cpu, kmemleak scan may be cpu intensive and can 816 stall user tasks at times. This option enables/disables automatic 817 kmemleak scan at boot up. 818 819 Say N here to disable kmemleak auto scan thread to stop automatic 820 scanning. Disabling this option disables automatic reporting of 821 memory leaks. 822 823 If unsure, say Y. 824 825config DEBUG_STACK_USAGE 826 bool "Stack utilization instrumentation" 827 depends on DEBUG_KERNEL && !IA64 828 help 829 Enables the display of the minimum amount of free stack which each 830 task has ever had available in the sysrq-T and sysrq-P debug output. 831 832 This option will slow down process creation somewhat. 833 834config SCHED_STACK_END_CHECK 835 bool "Detect stack corruption on calls to schedule()" 836 depends on DEBUG_KERNEL 837 default n 838 help 839 This option checks for a stack overrun on calls to schedule(). 840 If the stack end location is found to be over written always panic as 841 the content of the corrupted region can no longer be trusted. 842 This is to ensure no erroneous behaviour occurs which could result in 843 data corruption or a sporadic crash at a later stage once the region 844 is examined. The runtime overhead introduced is minimal. 845 846config ARCH_HAS_DEBUG_VM_PGTABLE 847 bool 848 help 849 An architecture should select this when it can successfully 850 build and run DEBUG_VM_PGTABLE. 851 852config DEBUG_VM_IRQSOFF 853 def_bool DEBUG_VM && !PREEMPT_RT 854 855config DEBUG_VM 856 bool "Debug VM" 857 depends on DEBUG_KERNEL 858 help 859 Enable this to turn on extended checks in the virtual-memory system 860 that may impact performance. 861 862 If unsure, say N. 863 864config DEBUG_VM_MAPLE_TREE 865 bool "Debug VM maple trees" 866 depends on DEBUG_VM 867 select DEBUG_MAPLE_TREE 868 help 869 Enable VM maple tree debugging information and extra validations. 870 871 If unsure, say N. 872 873config DEBUG_VM_RB 874 bool "Debug VM red-black trees" 875 depends on DEBUG_VM 876 help 877 Enable VM red-black tree debugging information and extra validations. 878 879 If unsure, say N. 880 881config DEBUG_VM_PGFLAGS 882 bool "Debug page-flags operations" 883 depends on DEBUG_VM 884 help 885 Enables extra validation on page flags operations. 886 887 If unsure, say N. 888 889config DEBUG_VM_PGTABLE 890 bool "Debug arch page table for semantics compliance" 891 depends on MMU 892 depends on ARCH_HAS_DEBUG_VM_PGTABLE 893 default y if DEBUG_VM 894 help 895 This option provides a debug method which can be used to test 896 architecture page table helper functions on various platforms in 897 verifying if they comply with expected generic MM semantics. This 898 will help architecture code in making sure that any changes or 899 new additions of these helpers still conform to expected 900 semantics of the generic MM. Platforms will have to opt in for 901 this through ARCH_HAS_DEBUG_VM_PGTABLE. 902 903 If unsure, say N. 904 905config ARCH_HAS_DEBUG_VIRTUAL 906 bool 907 908config DEBUG_VIRTUAL 909 bool "Debug VM translations" 910 depends on DEBUG_KERNEL && ARCH_HAS_DEBUG_VIRTUAL 911 help 912 Enable some costly sanity checks in virtual to page code. This can 913 catch mistakes with virt_to_page() and friends. 914 915 If unsure, say N. 916 917config DEBUG_NOMMU_REGIONS 918 bool "Debug the global anon/private NOMMU mapping region tree" 919 depends on DEBUG_KERNEL && !MMU 920 help 921 This option causes the global tree of anonymous and private mapping 922 regions to be regularly checked for invalid topology. 923 924config DEBUG_MEMORY_INIT 925 bool "Debug memory initialisation" if EXPERT 926 default !EXPERT 927 help 928 Enable this for additional checks during memory initialisation. 929 The sanity checks verify aspects of the VM such as the memory model 930 and other information provided by the architecture. Verbose 931 information will be printed at KERN_DEBUG loglevel depending 932 on the mminit_loglevel= command-line option. 933 934 If unsure, say Y 935 936config MEMORY_NOTIFIER_ERROR_INJECT 937 tristate "Memory hotplug notifier error injection module" 938 depends on MEMORY_HOTPLUG && NOTIFIER_ERROR_INJECTION 939 help 940 This option provides the ability to inject artificial errors to 941 memory hotplug notifier chain callbacks. It is controlled through 942 debugfs interface under /sys/kernel/debug/notifier-error-inject/memory 943 944 If the notifier call chain should be failed with some events 945 notified, write the error code to "actions/<notifier event>/error". 946 947 Example: Inject memory hotplug offline error (-12 == -ENOMEM) 948 949 # cd /sys/kernel/debug/notifier-error-inject/memory 950 # echo -12 > actions/MEM_GOING_OFFLINE/error 951 # echo offline > /sys/devices/system/memory/memoryXXX/state 952 bash: echo: write error: Cannot allocate memory 953 954 To compile this code as a module, choose M here: the module will 955 be called memory-notifier-error-inject. 956 957 If unsure, say N. 958 959config DEBUG_PER_CPU_MAPS 960 bool "Debug access to per_cpu maps" 961 depends on DEBUG_KERNEL 962 depends on SMP 963 help 964 Say Y to verify that the per_cpu map being accessed has 965 been set up. This adds a fair amount of code to kernel memory 966 and decreases performance. 967 968 Say N if unsure. 969 970config DEBUG_KMAP_LOCAL 971 bool "Debug kmap_local temporary mappings" 972 depends on DEBUG_KERNEL && KMAP_LOCAL 973 help 974 This option enables additional error checking for the kmap_local 975 infrastructure. Disable for production use. 976 977config ARCH_SUPPORTS_KMAP_LOCAL_FORCE_MAP 978 bool 979 980config DEBUG_KMAP_LOCAL_FORCE_MAP 981 bool "Enforce kmap_local temporary mappings" 982 depends on DEBUG_KERNEL && ARCH_SUPPORTS_KMAP_LOCAL_FORCE_MAP 983 select KMAP_LOCAL 984 select DEBUG_KMAP_LOCAL 985 help 986 This option enforces temporary mappings through the kmap_local 987 mechanism for non-highmem pages and on non-highmem systems. 988 Disable this for production systems! 989 990config DEBUG_HIGHMEM 991 bool "Highmem debugging" 992 depends on DEBUG_KERNEL && HIGHMEM 993 select DEBUG_KMAP_LOCAL_FORCE_MAP if ARCH_SUPPORTS_KMAP_LOCAL_FORCE_MAP 994 select DEBUG_KMAP_LOCAL 995 help 996 This option enables additional error checking for high memory 997 systems. Disable for production systems. 998 999config HAVE_DEBUG_STACKOVERFLOW 1000 bool 1001 1002config DEBUG_STACKOVERFLOW 1003 bool "Check for stack overflows" 1004 depends on DEBUG_KERNEL && HAVE_DEBUG_STACKOVERFLOW 1005 help 1006 Say Y here if you want to check for overflows of kernel, IRQ 1007 and exception stacks (if your architecture uses them). This 1008 option will show detailed messages if free stack space drops 1009 below a certain limit. 1010 1011 These kinds of bugs usually occur when call-chains in the 1012 kernel get too deep, especially when interrupts are 1013 involved. 1014 1015 Use this in cases where you see apparently random memory 1016 corruption, especially if it appears in 'struct thread_info' 1017 1018 If in doubt, say "N". 1019 1020source "lib/Kconfig.kasan" 1021source "lib/Kconfig.kfence" 1022source "lib/Kconfig.kmsan" 1023 1024endmenu # "Memory Debugging" 1025 1026config DEBUG_SHIRQ 1027 bool "Debug shared IRQ handlers" 1028 depends on DEBUG_KERNEL 1029 help 1030 Enable this to generate a spurious interrupt just before a shared 1031 interrupt handler is deregistered (generating one when registering 1032 is currently disabled). Drivers need to handle this correctly. Some 1033 don't and need to be caught. 1034 1035menu "Debug Oops, Lockups and Hangs" 1036 1037config PANIC_ON_OOPS 1038 bool "Panic on Oops" 1039 help 1040 Say Y here to enable the kernel to panic when it oopses. This 1041 has the same effect as setting oops=panic on the kernel command 1042 line. 1043 1044 This feature is useful to ensure that the kernel does not do 1045 anything erroneous after an oops which could result in data 1046 corruption or other issues. 1047 1048 Say N if unsure. 1049 1050config PANIC_ON_OOPS_VALUE 1051 int 1052 range 0 1 1053 default 0 if !PANIC_ON_OOPS 1054 default 1 if PANIC_ON_OOPS 1055 1056config PANIC_TIMEOUT 1057 int "panic timeout" 1058 default 0 1059 help 1060 Set the timeout value (in seconds) until a reboot occurs when 1061 the kernel panics. If n = 0, then we wait forever. A timeout 1062 value n > 0 will wait n seconds before rebooting, while a timeout 1063 value n < 0 will reboot immediately. 1064 1065config LOCKUP_DETECTOR 1066 bool 1067 1068config SOFTLOCKUP_DETECTOR 1069 bool "Detect Soft Lockups" 1070 depends on DEBUG_KERNEL && !S390 1071 select LOCKUP_DETECTOR 1072 help 1073 Say Y here to enable the kernel to act as a watchdog to detect 1074 soft lockups. 1075 1076 Softlockups are bugs that cause the kernel to loop in kernel 1077 mode for more than 20 seconds, without giving other tasks a 1078 chance to run. The current stack trace is displayed upon 1079 detection and the system will stay locked up. 1080 1081config BOOTPARAM_SOFTLOCKUP_PANIC 1082 bool "Panic (Reboot) On Soft Lockups" 1083 depends on SOFTLOCKUP_DETECTOR 1084 help 1085 Say Y here to enable the kernel to panic on "soft lockups", 1086 which are bugs that cause the kernel to loop in kernel 1087 mode for more than 20 seconds (configurable using the watchdog_thresh 1088 sysctl), without giving other tasks a chance to run. 1089 1090 The panic can be used in combination with panic_timeout, 1091 to cause the system to reboot automatically after a 1092 lockup has been detected. This feature is useful for 1093 high-availability systems that have uptime guarantees and 1094 where a lockup must be resolved ASAP. 1095 1096 Say N if unsure. 1097 1098config HARDLOCKUP_DETECTOR_PERF 1099 bool 1100 select SOFTLOCKUP_DETECTOR 1101 1102# 1103# Enables a timestamp based low pass filter to compensate for perf based 1104# hard lockup detection which runs too fast due to turbo modes. 1105# 1106config HARDLOCKUP_CHECK_TIMESTAMP 1107 bool 1108 1109# 1110# arch/ can define HAVE_HARDLOCKUP_DETECTOR_ARCH to provide their own hard 1111# lockup detector rather than the perf based detector. 1112# 1113config HARDLOCKUP_DETECTOR 1114 bool "Detect Hard Lockups" 1115 depends on DEBUG_KERNEL && !S390 1116 depends on HAVE_HARDLOCKUP_DETECTOR_PERF || HAVE_HARDLOCKUP_DETECTOR_ARCH 1117 select LOCKUP_DETECTOR 1118 select HARDLOCKUP_DETECTOR_PERF if HAVE_HARDLOCKUP_DETECTOR_PERF 1119 help 1120 Say Y here to enable the kernel to act as a watchdog to detect 1121 hard lockups. 1122 1123 Hardlockups are bugs that cause the CPU to loop in kernel mode 1124 for more than 10 seconds, without letting other interrupts have a 1125 chance to run. The current stack trace is displayed upon detection 1126 and the system will stay locked up. 1127 1128config BOOTPARAM_HARDLOCKUP_PANIC 1129 bool "Panic (Reboot) On Hard Lockups" 1130 depends on HARDLOCKUP_DETECTOR 1131 help 1132 Say Y here to enable the kernel to panic on "hard lockups", 1133 which are bugs that cause the kernel to loop in kernel 1134 mode with interrupts disabled for more than 10 seconds (configurable 1135 using the watchdog_thresh sysctl). 1136 1137 Say N if unsure. 1138 1139config DETECT_HUNG_TASK 1140 bool "Detect Hung Tasks" 1141 depends on DEBUG_KERNEL 1142 default SOFTLOCKUP_DETECTOR 1143 help 1144 Say Y here to enable the kernel to detect "hung tasks", 1145 which are bugs that cause the task to be stuck in 1146 uninterruptible "D" state indefinitely. 1147 1148 When a hung task is detected, the kernel will print the 1149 current stack trace (which you should report), but the 1150 task will stay in uninterruptible state. If lockdep is 1151 enabled then all held locks will also be reported. This 1152 feature has negligible overhead. 1153 1154config DEFAULT_HUNG_TASK_TIMEOUT 1155 int "Default timeout for hung task detection (in seconds)" 1156 depends on DETECT_HUNG_TASK 1157 default 120 1158 help 1159 This option controls the default timeout (in seconds) used 1160 to determine when a task has become non-responsive and should 1161 be considered hung. 1162 1163 It can be adjusted at runtime via the kernel.hung_task_timeout_secs 1164 sysctl or by writing a value to 1165 /proc/sys/kernel/hung_task_timeout_secs. 1166 1167 A timeout of 0 disables the check. The default is two minutes. 1168 Keeping the default should be fine in most cases. 1169 1170config BOOTPARAM_HUNG_TASK_PANIC 1171 bool "Panic (Reboot) On Hung Tasks" 1172 depends on DETECT_HUNG_TASK 1173 help 1174 Say Y here to enable the kernel to panic on "hung tasks", 1175 which are bugs that cause the kernel to leave a task stuck 1176 in uninterruptible "D" state. 1177 1178 The panic can be used in combination with panic_timeout, 1179 to cause the system to reboot automatically after a 1180 hung task has been detected. This feature is useful for 1181 high-availability systems that have uptime guarantees and 1182 where a hung tasks must be resolved ASAP. 1183 1184 Say N if unsure. 1185 1186config WQ_WATCHDOG 1187 bool "Detect Workqueue Stalls" 1188 depends on DEBUG_KERNEL 1189 help 1190 Say Y here to enable stall detection on workqueues. If a 1191 worker pool doesn't make forward progress on a pending work 1192 item for over a given amount of time, 30s by default, a 1193 warning message is printed along with dump of workqueue 1194 state. This can be configured through kernel parameter 1195 "workqueue.watchdog_thresh" and its sysfs counterpart. 1196 1197config TEST_LOCKUP 1198 tristate "Test module to generate lockups" 1199 depends on m 1200 help 1201 This builds the "test_lockup" module that helps to make sure 1202 that watchdogs and lockup detectors are working properly. 1203 1204 Depending on module parameters it could emulate soft or hard 1205 lockup, "hung task", or locking arbitrary lock for a long time. 1206 Also it could generate series of lockups with cooling-down periods. 1207 1208 If unsure, say N. 1209 1210endmenu # "Debug lockups and hangs" 1211 1212menu "Scheduler Debugging" 1213 1214config SCHED_DEBUG 1215 bool "Collect scheduler debugging info" 1216 depends on DEBUG_KERNEL && PROC_FS 1217 default y 1218 help 1219 If you say Y here, the /proc/sched_debug file will be provided 1220 that can help debug the scheduler. The runtime overhead of this 1221 option is minimal. 1222 1223config SCHED_INFO 1224 bool 1225 default n 1226 1227config SCHEDSTATS 1228 bool "Collect scheduler statistics" 1229 depends on DEBUG_KERNEL && PROC_FS 1230 select SCHED_INFO 1231 help 1232 If you say Y here, additional code will be inserted into the 1233 scheduler and related routines to collect statistics about 1234 scheduler behavior and provide them in /proc/schedstat. These 1235 stats may be useful for both tuning and debugging the scheduler 1236 If you aren't debugging the scheduler or trying to tune a specific 1237 application, you can say N to avoid the very slight overhead 1238 this adds. 1239 1240endmenu 1241 1242config DEBUG_TIMEKEEPING 1243 bool "Enable extra timekeeping sanity checking" 1244 help 1245 This option will enable additional timekeeping sanity checks 1246 which may be helpful when diagnosing issues where timekeeping 1247 problems are suspected. 1248 1249 This may include checks in the timekeeping hotpaths, so this 1250 option may have a (very small) performance impact to some 1251 workloads. 1252 1253 If unsure, say N. 1254 1255config DEBUG_PREEMPT 1256 bool "Debug preemptible kernel" 1257 depends on DEBUG_KERNEL && PREEMPTION && TRACE_IRQFLAGS_SUPPORT 1258 default y 1259 help 1260 If you say Y here then the kernel will use a debug variant of the 1261 commonly used smp_processor_id() function and will print warnings 1262 if kernel code uses it in a preemption-unsafe way. Also, the kernel 1263 will detect preemption count underflows. 1264 1265menu "Lock Debugging (spinlocks, mutexes, etc...)" 1266 1267config LOCK_DEBUGGING_SUPPORT 1268 bool 1269 depends on TRACE_IRQFLAGS_SUPPORT && STACKTRACE_SUPPORT && LOCKDEP_SUPPORT 1270 default y 1271 1272config PROVE_LOCKING 1273 bool "Lock debugging: prove locking correctness" 1274 depends on DEBUG_KERNEL && LOCK_DEBUGGING_SUPPORT 1275 select LOCKDEP 1276 select DEBUG_SPINLOCK 1277 select DEBUG_MUTEXES if !PREEMPT_RT 1278 select DEBUG_RT_MUTEXES if RT_MUTEXES 1279 select DEBUG_RWSEMS 1280 select DEBUG_WW_MUTEX_SLOWPATH 1281 select DEBUG_LOCK_ALLOC 1282 select PREEMPT_COUNT if !ARCH_NO_PREEMPT 1283 select TRACE_IRQFLAGS 1284 default n 1285 help 1286 This feature enables the kernel to prove that all locking 1287 that occurs in the kernel runtime is mathematically 1288 correct: that under no circumstance could an arbitrary (and 1289 not yet triggered) combination of observed locking 1290 sequences (on an arbitrary number of CPUs, running an 1291 arbitrary number of tasks and interrupt contexts) cause a 1292 deadlock. 1293 1294 In short, this feature enables the kernel to report locking 1295 related deadlocks before they actually occur. 1296 1297 The proof does not depend on how hard and complex a 1298 deadlock scenario would be to trigger: how many 1299 participant CPUs, tasks and irq-contexts would be needed 1300 for it to trigger. The proof also does not depend on 1301 timing: if a race and a resulting deadlock is possible 1302 theoretically (no matter how unlikely the race scenario 1303 is), it will be proven so and will immediately be 1304 reported by the kernel (once the event is observed that 1305 makes the deadlock theoretically possible). 1306 1307 If a deadlock is impossible (i.e. the locking rules, as 1308 observed by the kernel, are mathematically correct), the 1309 kernel reports nothing. 1310 1311 NOTE: this feature can also be enabled for rwlocks, mutexes 1312 and rwsems - in which case all dependencies between these 1313 different locking variants are observed and mapped too, and 1314 the proof of observed correctness is also maintained for an 1315 arbitrary combination of these separate locking variants. 1316 1317 For more details, see Documentation/locking/lockdep-design.rst. 1318 1319config PROVE_RAW_LOCK_NESTING 1320 bool "Enable raw_spinlock - spinlock nesting checks" 1321 depends on PROVE_LOCKING 1322 default n 1323 help 1324 Enable the raw_spinlock vs. spinlock nesting checks which ensure 1325 that the lock nesting rules for PREEMPT_RT enabled kernels are 1326 not violated. 1327 1328 NOTE: There are known nesting problems. So if you enable this 1329 option expect lockdep splats until these problems have been fully 1330 addressed which is work in progress. This config switch allows to 1331 identify and analyze these problems. It will be removed and the 1332 check permanently enabled once the main issues have been fixed. 1333 1334 If unsure, select N. 1335 1336config LOCK_STAT 1337 bool "Lock usage statistics" 1338 depends on DEBUG_KERNEL && LOCK_DEBUGGING_SUPPORT 1339 select LOCKDEP 1340 select DEBUG_SPINLOCK 1341 select DEBUG_MUTEXES if !PREEMPT_RT 1342 select DEBUG_RT_MUTEXES if RT_MUTEXES 1343 select DEBUG_LOCK_ALLOC 1344 default n 1345 help 1346 This feature enables tracking lock contention points 1347 1348 For more details, see Documentation/locking/lockstat.rst 1349 1350 This also enables lock events required by "perf lock", 1351 subcommand of perf. 1352 If you want to use "perf lock", you also need to turn on 1353 CONFIG_EVENT_TRACING. 1354 1355 CONFIG_LOCK_STAT defines "contended" and "acquired" lock events. 1356 (CONFIG_LOCKDEP defines "acquire" and "release" events.) 1357 1358config DEBUG_RT_MUTEXES 1359 bool "RT Mutex debugging, deadlock detection" 1360 depends on DEBUG_KERNEL && RT_MUTEXES 1361 help 1362 This allows rt mutex semantics violations and rt mutex related 1363 deadlocks (lockups) to be detected and reported automatically. 1364 1365config DEBUG_SPINLOCK 1366 bool "Spinlock and rw-lock debugging: basic checks" 1367 depends on DEBUG_KERNEL 1368 select UNINLINE_SPIN_UNLOCK 1369 help 1370 Say Y here and build SMP to catch missing spinlock initialization 1371 and certain other kinds of spinlock errors commonly made. This is 1372 best used in conjunction with the NMI watchdog so that spinlock 1373 deadlocks are also debuggable. 1374 1375config DEBUG_MUTEXES 1376 bool "Mutex debugging: basic checks" 1377 depends on DEBUG_KERNEL && !PREEMPT_RT 1378 help 1379 This feature allows mutex semantics violations to be detected and 1380 reported. 1381 1382config DEBUG_WW_MUTEX_SLOWPATH 1383 bool "Wait/wound mutex debugging: Slowpath testing" 1384 depends on DEBUG_KERNEL && LOCK_DEBUGGING_SUPPORT 1385 select DEBUG_LOCK_ALLOC 1386 select DEBUG_SPINLOCK 1387 select DEBUG_MUTEXES if !PREEMPT_RT 1388 select DEBUG_RT_MUTEXES if PREEMPT_RT 1389 help 1390 This feature enables slowpath testing for w/w mutex users by 1391 injecting additional -EDEADLK wound/backoff cases. Together with 1392 the full mutex checks enabled with (CONFIG_PROVE_LOCKING) this 1393 will test all possible w/w mutex interface abuse with the 1394 exception of simply not acquiring all the required locks. 1395 Note that this feature can introduce significant overhead, so 1396 it really should not be enabled in a production or distro kernel, 1397 even a debug kernel. If you are a driver writer, enable it. If 1398 you are a distro, do not. 1399 1400config DEBUG_RWSEMS 1401 bool "RW Semaphore debugging: basic checks" 1402 depends on DEBUG_KERNEL 1403 help 1404 This debugging feature allows mismatched rw semaphore locks 1405 and unlocks to be detected and reported. 1406 1407config DEBUG_LOCK_ALLOC 1408 bool "Lock debugging: detect incorrect freeing of live locks" 1409 depends on DEBUG_KERNEL && LOCK_DEBUGGING_SUPPORT 1410 select DEBUG_SPINLOCK 1411 select DEBUG_MUTEXES if !PREEMPT_RT 1412 select DEBUG_RT_MUTEXES if RT_MUTEXES 1413 select LOCKDEP 1414 help 1415 This feature will check whether any held lock (spinlock, rwlock, 1416 mutex or rwsem) is incorrectly freed by the kernel, via any of the 1417 memory-freeing routines (kfree(), kmem_cache_free(), free_pages(), 1418 vfree(), etc.), whether a live lock is incorrectly reinitialized via 1419 spin_lock_init()/mutex_init()/etc., or whether there is any lock 1420 held during task exit. 1421 1422config LOCKDEP 1423 bool 1424 depends on DEBUG_KERNEL && LOCK_DEBUGGING_SUPPORT 1425 select STACKTRACE 1426 select KALLSYMS 1427 select KALLSYMS_ALL 1428 1429config LOCKDEP_SMALL 1430 bool 1431 1432config LOCKDEP_BITS 1433 int "Bitsize for MAX_LOCKDEP_ENTRIES" 1434 depends on LOCKDEP && !LOCKDEP_SMALL 1435 range 10 30 1436 default 15 1437 help 1438 Try increasing this value if you hit "BUG: MAX_LOCKDEP_ENTRIES too low!" message. 1439 1440config LOCKDEP_CHAINS_BITS 1441 int "Bitsize for MAX_LOCKDEP_CHAINS" 1442 depends on LOCKDEP && !LOCKDEP_SMALL 1443 range 10 30 1444 default 16 1445 help 1446 Try increasing this value if you hit "BUG: MAX_LOCKDEP_CHAINS too low!" message. 1447 1448config LOCKDEP_STACK_TRACE_BITS 1449 int "Bitsize for MAX_STACK_TRACE_ENTRIES" 1450 depends on LOCKDEP && !LOCKDEP_SMALL 1451 range 10 30 1452 default 19 1453 help 1454 Try increasing this value if you hit "BUG: MAX_STACK_TRACE_ENTRIES too low!" message. 1455 1456config LOCKDEP_STACK_TRACE_HASH_BITS 1457 int "Bitsize for STACK_TRACE_HASH_SIZE" 1458 depends on LOCKDEP && !LOCKDEP_SMALL 1459 range 10 30 1460 default 14 1461 help 1462 Try increasing this value if you need large MAX_STACK_TRACE_ENTRIES. 1463 1464config LOCKDEP_CIRCULAR_QUEUE_BITS 1465 int "Bitsize for elements in circular_queue struct" 1466 depends on LOCKDEP 1467 range 10 30 1468 default 12 1469 help 1470 Try increasing this value if you hit "lockdep bfs error:-1" warning due to __cq_enqueue() failure. 1471 1472config DEBUG_LOCKDEP 1473 bool "Lock dependency engine debugging" 1474 depends on DEBUG_KERNEL && LOCKDEP 1475 select DEBUG_IRQFLAGS 1476 help 1477 If you say Y here, the lock dependency engine will do 1478 additional runtime checks to debug itself, at the price 1479 of more runtime overhead. 1480 1481config DEBUG_ATOMIC_SLEEP 1482 bool "Sleep inside atomic section checking" 1483 select PREEMPT_COUNT 1484 depends on DEBUG_KERNEL 1485 depends on !ARCH_NO_PREEMPT 1486 help 1487 If you say Y here, various routines which may sleep will become very 1488 noisy if they are called inside atomic sections: when a spinlock is 1489 held, inside an rcu read side critical section, inside preempt disabled 1490 sections, inside an interrupt, etc... 1491 1492config DEBUG_LOCKING_API_SELFTESTS 1493 bool "Locking API boot-time self-tests" 1494 depends on DEBUG_KERNEL 1495 help 1496 Say Y here if you want the kernel to run a short self-test during 1497 bootup. The self-test checks whether common types of locking bugs 1498 are detected by debugging mechanisms or not. (if you disable 1499 lock debugging then those bugs won't be detected of course.) 1500 The following locking APIs are covered: spinlocks, rwlocks, 1501 mutexes and rwsems. 1502 1503config LOCK_TORTURE_TEST 1504 tristate "torture tests for locking" 1505 depends on DEBUG_KERNEL 1506 select TORTURE_TEST 1507 help 1508 This option provides a kernel module that runs torture tests 1509 on kernel locking primitives. The kernel module may be built 1510 after the fact on the running kernel to be tested, if desired. 1511 1512 Say Y here if you want kernel locking-primitive torture tests 1513 to be built into the kernel. 1514 Say M if you want these torture tests to build as a module. 1515 Say N if you are unsure. 1516 1517config WW_MUTEX_SELFTEST 1518 tristate "Wait/wound mutex selftests" 1519 help 1520 This option provides a kernel module that runs tests on the 1521 on the struct ww_mutex locking API. 1522 1523 It is recommended to enable DEBUG_WW_MUTEX_SLOWPATH in conjunction 1524 with this test harness. 1525 1526 Say M if you want these self tests to build as a module. 1527 Say N if you are unsure. 1528 1529config SCF_TORTURE_TEST 1530 tristate "torture tests for smp_call_function*()" 1531 depends on DEBUG_KERNEL 1532 select TORTURE_TEST 1533 help 1534 This option provides a kernel module that runs torture tests 1535 on the smp_call_function() family of primitives. The kernel 1536 module may be built after the fact on the running kernel to 1537 be tested, if desired. 1538 1539config CSD_LOCK_WAIT_DEBUG 1540 bool "Debugging for csd_lock_wait(), called from smp_call_function*()" 1541 depends on DEBUG_KERNEL 1542 depends on 64BIT 1543 default n 1544 help 1545 This option enables debug prints when CPUs are slow to respond 1546 to the smp_call_function*() IPI wrappers. These debug prints 1547 include the IPI handler function currently executing (if any) 1548 and relevant stack traces. 1549 1550endmenu # lock debugging 1551 1552config TRACE_IRQFLAGS 1553 depends on TRACE_IRQFLAGS_SUPPORT 1554 bool 1555 help 1556 Enables hooks to interrupt enabling and disabling for 1557 either tracing or lock debugging. 1558 1559config TRACE_IRQFLAGS_NMI 1560 def_bool y 1561 depends on TRACE_IRQFLAGS 1562 depends on TRACE_IRQFLAGS_NMI_SUPPORT 1563 1564config DEBUG_IRQFLAGS 1565 bool "Debug IRQ flag manipulation" 1566 help 1567 Enables checks for potentially unsafe enabling or disabling of 1568 interrupts, such as calling raw_local_irq_restore() when interrupts 1569 are enabled. 1570 1571config STACKTRACE 1572 bool "Stack backtrace support" 1573 depends on STACKTRACE_SUPPORT 1574 help 1575 This option causes the kernel to create a /proc/pid/stack for 1576 every process, showing its current stack trace. 1577 It is also used by various kernel debugging features that require 1578 stack trace generation. 1579 1580config WARN_ALL_UNSEEDED_RANDOM 1581 bool "Warn for all uses of unseeded randomness" 1582 default n 1583 help 1584 Some parts of the kernel contain bugs relating to their use of 1585 cryptographically secure random numbers before it's actually possible 1586 to generate those numbers securely. This setting ensures that these 1587 flaws don't go unnoticed, by enabling a message, should this ever 1588 occur. This will allow people with obscure setups to know when things 1589 are going wrong, so that they might contact developers about fixing 1590 it. 1591 1592 Unfortunately, on some models of some architectures getting 1593 a fully seeded CRNG is extremely difficult, and so this can 1594 result in dmesg getting spammed for a surprisingly long 1595 time. This is really bad from a security perspective, and 1596 so architecture maintainers really need to do what they can 1597 to get the CRNG seeded sooner after the system is booted. 1598 However, since users cannot do anything actionable to 1599 address this, by default this option is disabled. 1600 1601 Say Y here if you want to receive warnings for all uses of 1602 unseeded randomness. This will be of use primarily for 1603 those developers interested in improving the security of 1604 Linux kernels running on their architecture (or 1605 subarchitecture). 1606 1607config DEBUG_KOBJECT 1608 bool "kobject debugging" 1609 depends on DEBUG_KERNEL 1610 help 1611 If you say Y here, some extra kobject debugging messages will be sent 1612 to the syslog. 1613 1614config DEBUG_KOBJECT_RELEASE 1615 bool "kobject release debugging" 1616 depends on DEBUG_OBJECTS_TIMERS 1617 help 1618 kobjects are reference counted objects. This means that their 1619 last reference count put is not predictable, and the kobject can 1620 live on past the point at which a driver decides to drop its 1621 initial reference to the kobject gained on allocation. An 1622 example of this would be a struct device which has just been 1623 unregistered. 1624 1625 However, some buggy drivers assume that after such an operation, 1626 the memory backing the kobject can be immediately freed. This 1627 goes completely against the principles of a refcounted object. 1628 1629 If you say Y here, the kernel will delay the release of kobjects 1630 on the last reference count to improve the visibility of this 1631 kind of kobject release bug. 1632 1633config HAVE_DEBUG_BUGVERBOSE 1634 bool 1635 1636menu "Debug kernel data structures" 1637 1638config DEBUG_LIST 1639 bool "Debug linked list manipulation" 1640 depends on DEBUG_KERNEL || BUG_ON_DATA_CORRUPTION 1641 help 1642 Enable this to turn on extended checks in the linked-list 1643 walking routines. 1644 1645 If unsure, say N. 1646 1647config DEBUG_PLIST 1648 bool "Debug priority linked list manipulation" 1649 depends on DEBUG_KERNEL 1650 help 1651 Enable this to turn on extended checks in the priority-ordered 1652 linked-list (plist) walking routines. This checks the entire 1653 list multiple times during each manipulation. 1654 1655 If unsure, say N. 1656 1657config DEBUG_SG 1658 bool "Debug SG table operations" 1659 depends on DEBUG_KERNEL 1660 help 1661 Enable this to turn on checks on scatter-gather tables. This can 1662 help find problems with drivers that do not properly initialize 1663 their sg tables. 1664 1665 If unsure, say N. 1666 1667config DEBUG_NOTIFIERS 1668 bool "Debug notifier call chains" 1669 depends on DEBUG_KERNEL 1670 help 1671 Enable this to turn on sanity checking for notifier call chains. 1672 This is most useful for kernel developers to make sure that 1673 modules properly unregister themselves from notifier chains. 1674 This is a relatively cheap check but if you care about maximum 1675 performance, say N. 1676 1677config BUG_ON_DATA_CORRUPTION 1678 bool "Trigger a BUG when data corruption is detected" 1679 select DEBUG_LIST 1680 help 1681 Select this option if the kernel should BUG when it encounters 1682 data corruption in kernel memory structures when they get checked 1683 for validity. 1684 1685 If unsure, say N. 1686 1687config DEBUG_MAPLE_TREE 1688 bool "Debug maple trees" 1689 depends on DEBUG_KERNEL 1690 help 1691 Enable maple tree debugging information and extra validations. 1692 1693 If unsure, say N. 1694 1695endmenu 1696 1697config DEBUG_CREDENTIALS 1698 bool "Debug credential management" 1699 depends on DEBUG_KERNEL 1700 help 1701 Enable this to turn on some debug checking for credential 1702 management. The additional code keeps track of the number of 1703 pointers from task_structs to any given cred struct, and checks to 1704 see that this number never exceeds the usage count of the cred 1705 struct. 1706 1707 Furthermore, if SELinux is enabled, this also checks that the 1708 security pointer in the cred struct is never seen to be invalid. 1709 1710 If unsure, say N. 1711 1712source "kernel/rcu/Kconfig.debug" 1713 1714config DEBUG_WQ_FORCE_RR_CPU 1715 bool "Force round-robin CPU selection for unbound work items" 1716 depends on DEBUG_KERNEL 1717 default n 1718 help 1719 Workqueue used to implicitly guarantee that work items queued 1720 without explicit CPU specified are put on the local CPU. This 1721 guarantee is no longer true and while local CPU is still 1722 preferred work items may be put on foreign CPUs. Kernel 1723 parameter "workqueue.debug_force_rr_cpu" is added to force 1724 round-robin CPU selection to flush out usages which depend on the 1725 now broken guarantee. This config option enables the debug 1726 feature by default. When enabled, memory and cache locality will 1727 be impacted. 1728 1729config CPU_HOTPLUG_STATE_CONTROL 1730 bool "Enable CPU hotplug state control" 1731 depends on DEBUG_KERNEL 1732 depends on HOTPLUG_CPU 1733 default n 1734 help 1735 Allows to write steps between "offline" and "online" to the CPUs 1736 sysfs target file so states can be stepped granular. This is a debug 1737 option for now as the hotplug machinery cannot be stopped and 1738 restarted at arbitrary points yet. 1739 1740 Say N if your are unsure. 1741 1742config LATENCYTOP 1743 bool "Latency measuring infrastructure" 1744 depends on DEBUG_KERNEL 1745 depends on STACKTRACE_SUPPORT 1746 depends on PROC_FS 1747 depends on FRAME_POINTER || MIPS || PPC || S390 || MICROBLAZE || ARM || ARC || X86 1748 select KALLSYMS 1749 select KALLSYMS_ALL 1750 select STACKTRACE 1751 select SCHEDSTATS 1752 help 1753 Enable this option if you want to use the LatencyTOP tool 1754 to find out which userspace is blocking on what kernel operations. 1755 1756config DEBUG_CGROUP_REF 1757 bool "Disable inlining of cgroup css reference count functions" 1758 depends on DEBUG_KERNEL 1759 depends on CGROUPS 1760 depends on KPROBES 1761 default n 1762 help 1763 Force cgroup css reference count functions to not be inlined so 1764 that they can be kprobed for debugging. 1765 1766source "kernel/trace/Kconfig" 1767 1768config PROVIDE_OHCI1394_DMA_INIT 1769 bool "Remote debugging over FireWire early on boot" 1770 depends on PCI && X86 1771 help 1772 If you want to debug problems which hang or crash the kernel early 1773 on boot and the crashing machine has a FireWire port, you can use 1774 this feature to remotely access the memory of the crashed machine 1775 over FireWire. This employs remote DMA as part of the OHCI1394 1776 specification which is now the standard for FireWire controllers. 1777 1778 With remote DMA, you can monitor the printk buffer remotely using 1779 firescope and access all memory below 4GB using fireproxy from gdb. 1780 Even controlling a kernel debugger is possible using remote DMA. 1781 1782 Usage: 1783 1784 If ohci1394_dma=early is used as boot parameter, it will initialize 1785 all OHCI1394 controllers which are found in the PCI config space. 1786 1787 As all changes to the FireWire bus such as enabling and disabling 1788 devices cause a bus reset and thereby disable remote DMA for all 1789 devices, be sure to have the cable plugged and FireWire enabled on 1790 the debugging host before booting the debug target for debugging. 1791 1792 This code (~1k) is freed after boot. By then, the firewire stack 1793 in charge of the OHCI-1394 controllers should be used instead. 1794 1795 See Documentation/core-api/debugging-via-ohci1394.rst for more information. 1796 1797source "samples/Kconfig" 1798 1799config ARCH_HAS_DEVMEM_IS_ALLOWED 1800 bool 1801 1802config STRICT_DEVMEM 1803 bool "Filter access to /dev/mem" 1804 depends on MMU && DEVMEM 1805 depends on ARCH_HAS_DEVMEM_IS_ALLOWED || GENERIC_LIB_DEVMEM_IS_ALLOWED 1806 default y if PPC || X86 || ARM64 1807 help 1808 If this option is disabled, you allow userspace (root) access to all 1809 of memory, including kernel and userspace memory. Accidental 1810 access to this is obviously disastrous, but specific access can 1811 be used by people debugging the kernel. Note that with PAT support 1812 enabled, even in this case there are restrictions on /dev/mem 1813 use due to the cache aliasing requirements. 1814 1815 If this option is switched on, and IO_STRICT_DEVMEM=n, the /dev/mem 1816 file only allows userspace access to PCI space and the BIOS code and 1817 data regions. This is sufficient for dosemu and X and all common 1818 users of /dev/mem. 1819 1820 If in doubt, say Y. 1821 1822config IO_STRICT_DEVMEM 1823 bool "Filter I/O access to /dev/mem" 1824 depends on STRICT_DEVMEM 1825 help 1826 If this option is disabled, you allow userspace (root) access to all 1827 io-memory regardless of whether a driver is actively using that 1828 range. Accidental access to this is obviously disastrous, but 1829 specific access can be used by people debugging kernel drivers. 1830 1831 If this option is switched on, the /dev/mem file only allows 1832 userspace access to *idle* io-memory ranges (see /proc/iomem) This 1833 may break traditional users of /dev/mem (dosemu, legacy X, etc...) 1834 if the driver using a given range cannot be disabled. 1835 1836 If in doubt, say Y. 1837 1838menu "$(SRCARCH) Debugging" 1839 1840source "arch/$(SRCARCH)/Kconfig.debug" 1841 1842endmenu 1843 1844menu "Kernel Testing and Coverage" 1845 1846source "lib/kunit/Kconfig" 1847 1848config NOTIFIER_ERROR_INJECTION 1849 tristate "Notifier error injection" 1850 depends on DEBUG_KERNEL 1851 select DEBUG_FS 1852 help 1853 This option provides the ability to inject artificial errors to 1854 specified notifier chain callbacks. It is useful to test the error 1855 handling of notifier call chain failures. 1856 1857 Say N if unsure. 1858 1859config PM_NOTIFIER_ERROR_INJECT 1860 tristate "PM notifier error injection module" 1861 depends on PM && NOTIFIER_ERROR_INJECTION 1862 default m if PM_DEBUG 1863 help 1864 This option provides the ability to inject artificial errors to 1865 PM notifier chain callbacks. It is controlled through debugfs 1866 interface /sys/kernel/debug/notifier-error-inject/pm 1867 1868 If the notifier call chain should be failed with some events 1869 notified, write the error code to "actions/<notifier event>/error". 1870 1871 Example: Inject PM suspend error (-12 = -ENOMEM) 1872 1873 # cd /sys/kernel/debug/notifier-error-inject/pm/ 1874 # echo -12 > actions/PM_SUSPEND_PREPARE/error 1875 # echo mem > /sys/power/state 1876 bash: echo: write error: Cannot allocate memory 1877 1878 To compile this code as a module, choose M here: the module will 1879 be called pm-notifier-error-inject. 1880 1881 If unsure, say N. 1882 1883config OF_RECONFIG_NOTIFIER_ERROR_INJECT 1884 tristate "OF reconfig notifier error injection module" 1885 depends on OF_DYNAMIC && NOTIFIER_ERROR_INJECTION 1886 help 1887 This option provides the ability to inject artificial errors to 1888 OF reconfig notifier chain callbacks. It is controlled 1889 through debugfs interface under 1890 /sys/kernel/debug/notifier-error-inject/OF-reconfig/ 1891 1892 If the notifier call chain should be failed with some events 1893 notified, write the error code to "actions/<notifier event>/error". 1894 1895 To compile this code as a module, choose M here: the module will 1896 be called of-reconfig-notifier-error-inject. 1897 1898 If unsure, say N. 1899 1900config NETDEV_NOTIFIER_ERROR_INJECT 1901 tristate "Netdev notifier error injection module" 1902 depends on NET && NOTIFIER_ERROR_INJECTION 1903 help 1904 This option provides the ability to inject artificial errors to 1905 netdevice notifier chain callbacks. It is controlled through debugfs 1906 interface /sys/kernel/debug/notifier-error-inject/netdev 1907 1908 If the notifier call chain should be failed with some events 1909 notified, write the error code to "actions/<notifier event>/error". 1910 1911 Example: Inject netdevice mtu change error (-22 = -EINVAL) 1912 1913 # cd /sys/kernel/debug/notifier-error-inject/netdev 1914 # echo -22 > actions/NETDEV_CHANGEMTU/error 1915 # ip link set eth0 mtu 1024 1916 RTNETLINK answers: Invalid argument 1917 1918 To compile this code as a module, choose M here: the module will 1919 be called netdev-notifier-error-inject. 1920 1921 If unsure, say N. 1922 1923config FUNCTION_ERROR_INJECTION 1924 bool "Fault-injections of functions" 1925 depends on HAVE_FUNCTION_ERROR_INJECTION && KPROBES 1926 help 1927 Add fault injections into various functions that are annotated with 1928 ALLOW_ERROR_INJECTION() in the kernel. BPF may also modify the return 1929 value of theses functions. This is useful to test error paths of code. 1930 1931 If unsure, say N 1932 1933config FAULT_INJECTION 1934 bool "Fault-injection framework" 1935 depends on DEBUG_KERNEL 1936 help 1937 Provide fault-injection framework. 1938 For more details, see Documentation/fault-injection/. 1939 1940config FAILSLAB 1941 bool "Fault-injection capability for kmalloc" 1942 depends on FAULT_INJECTION 1943 depends on SLAB || SLUB 1944 help 1945 Provide fault-injection capability for kmalloc. 1946 1947config FAIL_PAGE_ALLOC 1948 bool "Fault-injection capability for alloc_pages()" 1949 depends on FAULT_INJECTION 1950 help 1951 Provide fault-injection capability for alloc_pages(). 1952 1953config FAULT_INJECTION_USERCOPY 1954 bool "Fault injection capability for usercopy functions" 1955 depends on FAULT_INJECTION 1956 help 1957 Provides fault-injection capability to inject failures 1958 in usercopy functions (copy_from_user(), get_user(), ...). 1959 1960config FAIL_MAKE_REQUEST 1961 bool "Fault-injection capability for disk IO" 1962 depends on FAULT_INJECTION && BLOCK 1963 help 1964 Provide fault-injection capability for disk IO. 1965 1966config FAIL_IO_TIMEOUT 1967 bool "Fault-injection capability for faking disk interrupts" 1968 depends on FAULT_INJECTION && BLOCK 1969 help 1970 Provide fault-injection capability on end IO handling. This 1971 will make the block layer "forget" an interrupt as configured, 1972 thus exercising the error handling. 1973 1974 Only works with drivers that use the generic timeout handling, 1975 for others it won't do anything. 1976 1977config FAIL_FUTEX 1978 bool "Fault-injection capability for futexes" 1979 select DEBUG_FS 1980 depends on FAULT_INJECTION && FUTEX 1981 help 1982 Provide fault-injection capability for futexes. 1983 1984config FAULT_INJECTION_DEBUG_FS 1985 bool "Debugfs entries for fault-injection capabilities" 1986 depends on FAULT_INJECTION && SYSFS && DEBUG_FS 1987 help 1988 Enable configuration of fault-injection capabilities via debugfs. 1989 1990config FAIL_FUNCTION 1991 bool "Fault-injection capability for functions" 1992 depends on FAULT_INJECTION_DEBUG_FS && FUNCTION_ERROR_INJECTION 1993 help 1994 Provide function-based fault-injection capability. 1995 This will allow you to override a specific function with a return 1996 with given return value. As a result, function caller will see 1997 an error value and have to handle it. This is useful to test the 1998 error handling in various subsystems. 1999 2000config FAIL_MMC_REQUEST 2001 bool "Fault-injection capability for MMC IO" 2002 depends on FAULT_INJECTION_DEBUG_FS && MMC 2003 help 2004 Provide fault-injection capability for MMC IO. 2005 This will make the mmc core return data errors. This is 2006 useful to test the error handling in the mmc block device 2007 and to test how the mmc host driver handles retries from 2008 the block device. 2009 2010config FAIL_SUNRPC 2011 bool "Fault-injection capability for SunRPC" 2012 depends on FAULT_INJECTION_DEBUG_FS && SUNRPC_DEBUG 2013 help 2014 Provide fault-injection capability for SunRPC and 2015 its consumers. 2016 2017config FAULT_INJECTION_STACKTRACE_FILTER 2018 bool "stacktrace filter for fault-injection capabilities" 2019 depends on FAULT_INJECTION_DEBUG_FS && STACKTRACE_SUPPORT 2020 select STACKTRACE 2021 depends on FRAME_POINTER || MIPS || PPC || S390 || MICROBLAZE || ARM || ARC || X86 2022 help 2023 Provide stacktrace filter for fault-injection capabilities 2024 2025config ARCH_HAS_KCOV 2026 bool 2027 help 2028 An architecture should select this when it can successfully 2029 build and run with CONFIG_KCOV. This typically requires 2030 disabling instrumentation for some early boot code. 2031 2032config CC_HAS_SANCOV_TRACE_PC 2033 def_bool $(cc-option,-fsanitize-coverage=trace-pc) 2034 2035 2036config KCOV 2037 bool "Code coverage for fuzzing" 2038 depends on ARCH_HAS_KCOV 2039 depends on CC_HAS_SANCOV_TRACE_PC || GCC_PLUGINS 2040 depends on !ARCH_WANTS_NO_INSTR || HAVE_NOINSTR_HACK || \ 2041 GCC_VERSION >= 120000 || CLANG_VERSION >= 130000 2042 select DEBUG_FS 2043 select GCC_PLUGIN_SANCOV if !CC_HAS_SANCOV_TRACE_PC 2044 select OBJTOOL if HAVE_NOINSTR_HACK 2045 help 2046 KCOV exposes kernel code coverage information in a form suitable 2047 for coverage-guided fuzzing (randomized testing). 2048 2049 If RANDOMIZE_BASE is enabled, PC values will not be stable across 2050 different machines and across reboots. If you need stable PC values, 2051 disable RANDOMIZE_BASE. 2052 2053 For more details, see Documentation/dev-tools/kcov.rst. 2054 2055config KCOV_ENABLE_COMPARISONS 2056 bool "Enable comparison operands collection by KCOV" 2057 depends on KCOV 2058 depends on $(cc-option,-fsanitize-coverage=trace-cmp) 2059 help 2060 KCOV also exposes operands of every comparison in the instrumented 2061 code along with operand sizes and PCs of the comparison instructions. 2062 These operands can be used by fuzzing engines to improve the quality 2063 of fuzzing coverage. 2064 2065config KCOV_INSTRUMENT_ALL 2066 bool "Instrument all code by default" 2067 depends on KCOV 2068 default y 2069 help 2070 If you are doing generic system call fuzzing (like e.g. syzkaller), 2071 then you will want to instrument the whole kernel and you should 2072 say y here. If you are doing more targeted fuzzing (like e.g. 2073 filesystem fuzzing with AFL) then you will want to enable coverage 2074 for more specific subsets of files, and should say n here. 2075 2076config KCOV_IRQ_AREA_SIZE 2077 hex "Size of interrupt coverage collection area in words" 2078 depends on KCOV 2079 default 0x40000 2080 help 2081 KCOV uses preallocated per-cpu areas to collect coverage from 2082 soft interrupts. This specifies the size of those areas in the 2083 number of unsigned long words. 2084 2085menuconfig RUNTIME_TESTING_MENU 2086 bool "Runtime Testing" 2087 def_bool y 2088 2089if RUNTIME_TESTING_MENU 2090 2091config LKDTM 2092 tristate "Linux Kernel Dump Test Tool Module" 2093 depends on DEBUG_FS 2094 help 2095 This module enables testing of the different dumping mechanisms by 2096 inducing system failures at predefined crash points. 2097 If you don't need it: say N 2098 Choose M here to compile this code as a module. The module will be 2099 called lkdtm. 2100 2101 Documentation on how to use the module can be found in 2102 Documentation/fault-injection/provoke-crashes.rst 2103 2104config CPUMASK_KUNIT_TEST 2105 tristate "KUnit test for cpumask" if !KUNIT_ALL_TESTS 2106 depends on KUNIT 2107 default KUNIT_ALL_TESTS 2108 help 2109 Enable to turn on cpumask tests, running at boot or module load time. 2110 2111 For more information on KUnit and unit tests in general, please refer 2112 to the KUnit documentation in Documentation/dev-tools/kunit/. 2113 2114 If unsure, say N. 2115 2116config TEST_LIST_SORT 2117 tristate "Linked list sorting test" if !KUNIT_ALL_TESTS 2118 depends on KUNIT 2119 default KUNIT_ALL_TESTS 2120 help 2121 Enable this to turn on 'list_sort()' function test. This test is 2122 executed only once during system boot (so affects only boot time), 2123 or at module load time. 2124 2125 If unsure, say N. 2126 2127config TEST_MIN_HEAP 2128 tristate "Min heap test" 2129 depends on DEBUG_KERNEL || m 2130 help 2131 Enable this to turn on min heap function tests. This test is 2132 executed only once during system boot (so affects only boot time), 2133 or at module load time. 2134 2135 If unsure, say N. 2136 2137config TEST_SORT 2138 tristate "Array-based sort test" if !KUNIT_ALL_TESTS 2139 depends on KUNIT 2140 default KUNIT_ALL_TESTS 2141 help 2142 This option enables the self-test function of 'sort()' at boot, 2143 or at module load time. 2144 2145 If unsure, say N. 2146 2147config TEST_DIV64 2148 tristate "64bit/32bit division and modulo test" 2149 depends on DEBUG_KERNEL || m 2150 help 2151 Enable this to turn on 'do_div()' function test. This test is 2152 executed only once during system boot (so affects only boot time), 2153 or at module load time. 2154 2155 If unsure, say N. 2156 2157config KPROBES_SANITY_TEST 2158 tristate "Kprobes sanity tests" if !KUNIT_ALL_TESTS 2159 depends on DEBUG_KERNEL 2160 depends on KPROBES 2161 depends on KUNIT 2162 select STACKTRACE if ARCH_CORRECT_STACKTRACE_ON_KRETPROBE 2163 default KUNIT_ALL_TESTS 2164 help 2165 This option provides for testing basic kprobes functionality on 2166 boot. Samples of kprobe and kretprobe are inserted and 2167 verified for functionality. 2168 2169 Say N if you are unsure. 2170 2171config FPROBE_SANITY_TEST 2172 bool "Self test for fprobe" 2173 depends on DEBUG_KERNEL 2174 depends on FPROBE 2175 depends on KUNIT=y 2176 help 2177 This option will enable testing the fprobe when the system boot. 2178 A series of tests are made to verify that the fprobe is functioning 2179 properly. 2180 2181 Say N if you are unsure. 2182 2183config BACKTRACE_SELF_TEST 2184 tristate "Self test for the backtrace code" 2185 depends on DEBUG_KERNEL 2186 help 2187 This option provides a kernel module that can be used to test 2188 the kernel stack backtrace code. This option is not useful 2189 for distributions or general kernels, but only for kernel 2190 developers working on architecture code. 2191 2192 Note that if you want to also test saved backtraces, you will 2193 have to enable STACKTRACE as well. 2194 2195 Say N if you are unsure. 2196 2197config TEST_REF_TRACKER 2198 tristate "Self test for reference tracker" 2199 depends on DEBUG_KERNEL && STACKTRACE_SUPPORT 2200 select REF_TRACKER 2201 help 2202 This option provides a kernel module performing tests 2203 using reference tracker infrastructure. 2204 2205 Say N if you are unsure. 2206 2207config RBTREE_TEST 2208 tristate "Red-Black tree test" 2209 depends on DEBUG_KERNEL 2210 help 2211 A benchmark measuring the performance of the rbtree library. 2212 Also includes rbtree invariant checks. 2213 2214config REED_SOLOMON_TEST 2215 tristate "Reed-Solomon library test" 2216 depends on DEBUG_KERNEL || m 2217 select REED_SOLOMON 2218 select REED_SOLOMON_ENC16 2219 select REED_SOLOMON_DEC16 2220 help 2221 This option enables the self-test function of rslib at boot, 2222 or at module load time. 2223 2224 If unsure, say N. 2225 2226config INTERVAL_TREE_TEST 2227 tristate "Interval tree test" 2228 depends on DEBUG_KERNEL 2229 select INTERVAL_TREE 2230 help 2231 A benchmark measuring the performance of the interval tree library 2232 2233config PERCPU_TEST 2234 tristate "Per cpu operations test" 2235 depends on m && DEBUG_KERNEL 2236 help 2237 Enable this option to build test module which validates per-cpu 2238 operations. 2239 2240 If unsure, say N. 2241 2242config ATOMIC64_SELFTEST 2243 tristate "Perform an atomic64_t self-test" 2244 help 2245 Enable this option to test the atomic64_t functions at boot or 2246 at module load time. 2247 2248 If unsure, say N. 2249 2250config ASYNC_RAID6_TEST 2251 tristate "Self test for hardware accelerated raid6 recovery" 2252 depends on ASYNC_RAID6_RECOV 2253 select ASYNC_MEMCPY 2254 help 2255 This is a one-shot self test that permutes through the 2256 recovery of all the possible two disk failure scenarios for a 2257 N-disk array. Recovery is performed with the asynchronous 2258 raid6 recovery routines, and will optionally use an offload 2259 engine if one is available. 2260 2261 If unsure, say N. 2262 2263config TEST_HEXDUMP 2264 tristate "Test functions located in the hexdump module at runtime" 2265 2266config STRING_SELFTEST 2267 tristate "Test string functions at runtime" 2268 2269config TEST_STRING_HELPERS 2270 tristate "Test functions located in the string_helpers module at runtime" 2271 2272config TEST_KSTRTOX 2273 tristate "Test kstrto*() family of functions at runtime" 2274 2275config TEST_PRINTF 2276 tristate "Test printf() family of functions at runtime" 2277 2278config TEST_SCANF 2279 tristate "Test scanf() family of functions at runtime" 2280 2281config TEST_BITMAP 2282 tristate "Test bitmap_*() family of functions at runtime" 2283 help 2284 Enable this option to test the bitmap functions at boot. 2285 2286 If unsure, say N. 2287 2288config TEST_UUID 2289 tristate "Test functions located in the uuid module at runtime" 2290 2291config TEST_XARRAY 2292 tristate "Test the XArray code at runtime" 2293 2294config TEST_MAPLE_TREE 2295 depends on DEBUG_KERNEL 2296 select DEBUG_MAPLE_TREE 2297 tristate "Test the Maple Tree code at runtime" 2298 2299config TEST_RHASHTABLE 2300 tristate "Perform selftest on resizable hash table" 2301 help 2302 Enable this option to test the rhashtable functions at boot. 2303 2304 If unsure, say N. 2305 2306config TEST_IDA 2307 tristate "Perform selftest on IDA functions" 2308 2309config TEST_PARMAN 2310 tristate "Perform selftest on priority array manager" 2311 depends on PARMAN 2312 help 2313 Enable this option to test priority array manager on boot 2314 (or module load). 2315 2316 If unsure, say N. 2317 2318config TEST_IRQ_TIMINGS 2319 bool "IRQ timings selftest" 2320 depends on IRQ_TIMINGS 2321 help 2322 Enable this option to test the irq timings code on boot. 2323 2324 If unsure, say N. 2325 2326config TEST_LKM 2327 tristate "Test module loading with 'hello world' module" 2328 depends on m 2329 help 2330 This builds the "test_module" module that emits "Hello, world" 2331 on printk when loaded. It is designed to be used for basic 2332 evaluation of the module loading subsystem (for example when 2333 validating module verification). It lacks any extra dependencies, 2334 and will not normally be loaded by the system unless explicitly 2335 requested by name. 2336 2337 If unsure, say N. 2338 2339config TEST_BITOPS 2340 tristate "Test module for compilation of bitops operations" 2341 depends on m 2342 help 2343 This builds the "test_bitops" module that is much like the 2344 TEST_LKM module except that it does a basic exercise of the 2345 set/clear_bit macros and get_count_order/long to make sure there are 2346 no compiler warnings from C=1 sparse checker or -Wextra 2347 compilations. It has no dependencies and doesn't run or load unless 2348 explicitly requested by name. for example: modprobe test_bitops. 2349 2350 If unsure, say N. 2351 2352config TEST_VMALLOC 2353 tristate "Test module for stress/performance analysis of vmalloc allocator" 2354 default n 2355 depends on MMU 2356 depends on m 2357 help 2358 This builds the "test_vmalloc" module that should be used for 2359 stress and performance analysis. So, any new change for vmalloc 2360 subsystem can be evaluated from performance and stability point 2361 of view. 2362 2363 If unsure, say N. 2364 2365config TEST_USER_COPY 2366 tristate "Test user/kernel boundary protections" 2367 depends on m 2368 help 2369 This builds the "test_user_copy" module that runs sanity checks 2370 on the copy_to/from_user infrastructure, making sure basic 2371 user/kernel boundary testing is working. If it fails to load, 2372 a regression has been detected in the user/kernel memory boundary 2373 protections. 2374 2375 If unsure, say N. 2376 2377config TEST_BPF 2378 tristate "Test BPF filter functionality" 2379 depends on m && NET 2380 help 2381 This builds the "test_bpf" module that runs various test vectors 2382 against the BPF interpreter or BPF JIT compiler depending on the 2383 current setting. This is in particular useful for BPF JIT compiler 2384 development, but also to run regression tests against changes in 2385 the interpreter code. It also enables test stubs for eBPF maps and 2386 verifier used by user space verifier testsuite. 2387 2388 If unsure, say N. 2389 2390config TEST_BLACKHOLE_DEV 2391 tristate "Test blackhole netdev functionality" 2392 depends on m && NET 2393 help 2394 This builds the "test_blackhole_dev" module that validates the 2395 data path through this blackhole netdev. 2396 2397 If unsure, say N. 2398 2399config FIND_BIT_BENCHMARK 2400 tristate "Test find_bit functions" 2401 help 2402 This builds the "test_find_bit" module that measure find_*_bit() 2403 functions performance. 2404 2405 If unsure, say N. 2406 2407config TEST_FIRMWARE 2408 tristate "Test firmware loading via userspace interface" 2409 depends on FW_LOADER 2410 help 2411 This builds the "test_firmware" module that creates a userspace 2412 interface for testing firmware loading. This can be used to 2413 control the triggering of firmware loading without needing an 2414 actual firmware-using device. The contents can be rechecked by 2415 userspace. 2416 2417 If unsure, say N. 2418 2419config TEST_SYSCTL 2420 tristate "sysctl test driver" 2421 depends on PROC_SYSCTL 2422 help 2423 This builds the "test_sysctl" module. This driver enables to test the 2424 proc sysctl interfaces available to drivers safely without affecting 2425 production knobs which might alter system functionality. 2426 2427 If unsure, say N. 2428 2429config BITFIELD_KUNIT 2430 tristate "KUnit test bitfield functions at runtime" if !KUNIT_ALL_TESTS 2431 depends on KUNIT 2432 default KUNIT_ALL_TESTS 2433 help 2434 Enable this option to test the bitfield functions at boot. 2435 2436 KUnit tests run during boot and output the results to the debug log 2437 in TAP format (http://testanything.org/). Only useful for kernel devs 2438 running the KUnit test harness, and not intended for inclusion into a 2439 production build. 2440 2441 For more information on KUnit and unit tests in general please refer 2442 to the KUnit documentation in Documentation/dev-tools/kunit/. 2443 2444 If unsure, say N. 2445 2446config HASH_KUNIT_TEST 2447 tristate "KUnit Test for integer hash functions" if !KUNIT_ALL_TESTS 2448 depends on KUNIT 2449 default KUNIT_ALL_TESTS 2450 help 2451 Enable this option to test the kernel's string (<linux/stringhash.h>), and 2452 integer (<linux/hash.h>) hash functions on boot. 2453 2454 KUnit tests run during boot and output the results to the debug log 2455 in TAP format (https://testanything.org/). Only useful for kernel devs 2456 running the KUnit test harness, and not intended for inclusion into a 2457 production build. 2458 2459 For more information on KUnit and unit tests in general please refer 2460 to the KUnit documentation in Documentation/dev-tools/kunit/. 2461 2462 This is intended to help people writing architecture-specific 2463 optimized versions. If unsure, say N. 2464 2465config RESOURCE_KUNIT_TEST 2466 tristate "KUnit test for resource API" if !KUNIT_ALL_TESTS 2467 depends on KUNIT 2468 default KUNIT_ALL_TESTS 2469 help 2470 This builds the resource API unit test. 2471 Tests the logic of API provided by resource.c and ioport.h. 2472 For more information on KUnit and unit tests in general please refer 2473 to the KUnit documentation in Documentation/dev-tools/kunit/. 2474 2475 If unsure, say N. 2476 2477config SYSCTL_KUNIT_TEST 2478 tristate "KUnit test for sysctl" if !KUNIT_ALL_TESTS 2479 depends on KUNIT 2480 default KUNIT_ALL_TESTS 2481 help 2482 This builds the proc sysctl unit test, which runs on boot. 2483 Tests the API contract and implementation correctness of sysctl. 2484 For more information on KUnit and unit tests in general please refer 2485 to the KUnit documentation in Documentation/dev-tools/kunit/. 2486 2487 If unsure, say N. 2488 2489config LIST_KUNIT_TEST 2490 tristate "KUnit Test for Kernel Linked-list structures" if !KUNIT_ALL_TESTS 2491 depends on KUNIT 2492 default KUNIT_ALL_TESTS 2493 help 2494 This builds the linked list KUnit test suite. 2495 It tests that the API and basic functionality of the list_head type 2496 and associated macros. 2497 2498 KUnit tests run during boot and output the results to the debug log 2499 in TAP format (https://testanything.org/). Only useful for kernel devs 2500 running the KUnit test harness, and not intended for inclusion into a 2501 production build. 2502 2503 For more information on KUnit and unit tests in general please refer 2504 to the KUnit documentation in Documentation/dev-tools/kunit/. 2505 2506 If unsure, say N. 2507 2508config LINEAR_RANGES_TEST 2509 tristate "KUnit test for linear_ranges" 2510 depends on KUNIT 2511 select LINEAR_RANGES 2512 help 2513 This builds the linear_ranges unit test, which runs on boot. 2514 Tests the linear_ranges logic correctness. 2515 For more information on KUnit and unit tests in general please refer 2516 to the KUnit documentation in Documentation/dev-tools/kunit/. 2517 2518 If unsure, say N. 2519 2520config CMDLINE_KUNIT_TEST 2521 tristate "KUnit test for cmdline API" if !KUNIT_ALL_TESTS 2522 depends on KUNIT 2523 default KUNIT_ALL_TESTS 2524 help 2525 This builds the cmdline API unit test. 2526 Tests the logic of API provided by cmdline.c. 2527 For more information on KUnit and unit tests in general please refer 2528 to the KUnit documentation in Documentation/dev-tools/kunit/. 2529 2530 If unsure, say N. 2531 2532config BITS_TEST 2533 tristate "KUnit test for bits.h" if !KUNIT_ALL_TESTS 2534 depends on KUNIT 2535 default KUNIT_ALL_TESTS 2536 help 2537 This builds the bits unit test. 2538 Tests the logic of macros defined in bits.h. 2539 For more information on KUnit and unit tests in general please refer 2540 to the KUnit documentation in Documentation/dev-tools/kunit/. 2541 2542 If unsure, say N. 2543 2544config SLUB_KUNIT_TEST 2545 tristate "KUnit test for SLUB cache error detection" if !KUNIT_ALL_TESTS 2546 depends on SLUB_DEBUG && KUNIT 2547 default KUNIT_ALL_TESTS 2548 help 2549 This builds SLUB allocator unit test. 2550 Tests SLUB cache debugging functionality. 2551 For more information on KUnit and unit tests in general please refer 2552 to the KUnit documentation in Documentation/dev-tools/kunit/. 2553 2554 If unsure, say N. 2555 2556config RATIONAL_KUNIT_TEST 2557 tristate "KUnit test for rational.c" if !KUNIT_ALL_TESTS 2558 depends on KUNIT && RATIONAL 2559 default KUNIT_ALL_TESTS 2560 help 2561 This builds the rational math unit test. 2562 For more information on KUnit and unit tests in general please refer 2563 to the KUnit documentation in Documentation/dev-tools/kunit/. 2564 2565 If unsure, say N. 2566 2567config MEMCPY_KUNIT_TEST 2568 tristate "Test memcpy(), memmove(), and memset() functions at runtime" if !KUNIT_ALL_TESTS 2569 depends on KUNIT 2570 default KUNIT_ALL_TESTS 2571 help 2572 Builds unit tests for memcpy(), memmove(), and memset() functions. 2573 For more information on KUnit and unit tests in general please refer 2574 to the KUnit documentation in Documentation/dev-tools/kunit/. 2575 2576 If unsure, say N. 2577 2578config IS_SIGNED_TYPE_KUNIT_TEST 2579 tristate "Test is_signed_type() macro" if !KUNIT_ALL_TESTS 2580 depends on KUNIT 2581 default KUNIT_ALL_TESTS 2582 help 2583 Builds unit tests for the is_signed_type() macro. 2584 2585 For more information on KUnit and unit tests in general please refer 2586 to the KUnit documentation in Documentation/dev-tools/kunit/. 2587 2588 If unsure, say N. 2589 2590config OVERFLOW_KUNIT_TEST 2591 tristate "Test check_*_overflow() functions at runtime" if !KUNIT_ALL_TESTS 2592 depends on KUNIT 2593 default KUNIT_ALL_TESTS 2594 help 2595 Builds unit tests for the check_*_overflow(), size_*(), allocation, and 2596 related functions. 2597 2598 For more information on KUnit and unit tests in general please refer 2599 to the KUnit documentation in Documentation/dev-tools/kunit/. 2600 2601 If unsure, say N. 2602 2603config STACKINIT_KUNIT_TEST 2604 tristate "Test level of stack variable initialization" if !KUNIT_ALL_TESTS 2605 depends on KUNIT 2606 default KUNIT_ALL_TESTS 2607 help 2608 Test if the kernel is zero-initializing stack variables and 2609 padding. Coverage is controlled by compiler flags, 2610 CONFIG_INIT_STACK_ALL_PATTERN, CONFIG_INIT_STACK_ALL_ZERO, 2611 CONFIG_GCC_PLUGIN_STRUCTLEAK, CONFIG_GCC_PLUGIN_STRUCTLEAK_BYREF, 2612 or CONFIG_GCC_PLUGIN_STRUCTLEAK_BYREF_ALL. 2613 2614config FORTIFY_KUNIT_TEST 2615 tristate "Test fortified str*() and mem*() function internals at runtime" if !KUNIT_ALL_TESTS 2616 depends on KUNIT && FORTIFY_SOURCE 2617 default KUNIT_ALL_TESTS 2618 help 2619 Builds unit tests for checking internals of FORTIFY_SOURCE as used 2620 by the str*() and mem*() family of functions. For testing runtime 2621 traps of FORTIFY_SOURCE, see LKDTM's "FORTIFY_*" tests. 2622 2623config HW_BREAKPOINT_KUNIT_TEST 2624 bool "Test hw_breakpoint constraints accounting" if !KUNIT_ALL_TESTS 2625 depends on HAVE_HW_BREAKPOINT 2626 depends on KUNIT=y 2627 default KUNIT_ALL_TESTS 2628 help 2629 Tests for hw_breakpoint constraints accounting. 2630 2631 If unsure, say N. 2632 2633config STRSCPY_KUNIT_TEST 2634 tristate "Test strscpy*() family of functions at runtime" if !KUNIT_ALL_TESTS 2635 depends on KUNIT 2636 default KUNIT_ALL_TESTS 2637 2638config SIPHASH_KUNIT_TEST 2639 tristate "Perform selftest on siphash functions" if !KUNIT_ALL_TESTS 2640 depends on KUNIT 2641 default KUNIT_ALL_TESTS 2642 help 2643 Enable this option to test the kernel's siphash (<linux/siphash.h>) hash 2644 functions on boot (or module load). 2645 2646 This is intended to help people writing architecture-specific 2647 optimized versions. If unsure, say N. 2648 2649config TEST_UDELAY 2650 tristate "udelay test driver" 2651 help 2652 This builds the "udelay_test" module that helps to make sure 2653 that udelay() is working properly. 2654 2655 If unsure, say N. 2656 2657config TEST_STATIC_KEYS 2658 tristate "Test static keys" 2659 depends on m 2660 help 2661 Test the static key interfaces. 2662 2663 If unsure, say N. 2664 2665config TEST_DYNAMIC_DEBUG 2666 tristate "Test DYNAMIC_DEBUG" 2667 depends on DYNAMIC_DEBUG 2668 help 2669 This module registers a tracer callback to count enabled 2670 pr_debugs in a 'do_debugging' function, then alters their 2671 enablements, calls the function, and compares counts. 2672 2673 If unsure, say N. 2674 2675config TEST_KMOD 2676 tristate "kmod stress tester" 2677 depends on m 2678 depends on NETDEVICES && NET_CORE && INET # for TUN 2679 depends on BLOCK 2680 depends on PAGE_SIZE_LESS_THAN_256KB # for BTRFS 2681 select TEST_LKM 2682 select XFS_FS 2683 select TUN 2684 select BTRFS_FS 2685 help 2686 Test the kernel's module loading mechanism: kmod. kmod implements 2687 support to load modules using the Linux kernel's usermode helper. 2688 This test provides a series of tests against kmod. 2689 2690 Although technically you can either build test_kmod as a module or 2691 into the kernel we disallow building it into the kernel since 2692 it stress tests request_module() and this will very likely cause 2693 some issues by taking over precious threads available from other 2694 module load requests, ultimately this could be fatal. 2695 2696 To run tests run: 2697 2698 tools/testing/selftests/kmod/kmod.sh --help 2699 2700 If unsure, say N. 2701 2702config TEST_DEBUG_VIRTUAL 2703 tristate "Test CONFIG_DEBUG_VIRTUAL feature" 2704 depends on DEBUG_VIRTUAL 2705 help 2706 Test the kernel's ability to detect incorrect calls to 2707 virt_to_phys() done against the non-linear part of the 2708 kernel's virtual address map. 2709 2710 If unsure, say N. 2711 2712config TEST_MEMCAT_P 2713 tristate "Test memcat_p() helper function" 2714 help 2715 Test the memcat_p() helper for correctly merging two 2716 pointer arrays together. 2717 2718 If unsure, say N. 2719 2720config TEST_LIVEPATCH 2721 tristate "Test livepatching" 2722 default n 2723 depends on DYNAMIC_DEBUG 2724 depends on LIVEPATCH 2725 depends on m 2726 help 2727 Test kernel livepatching features for correctness. The tests will 2728 load test modules that will be livepatched in various scenarios. 2729 2730 To run all the livepatching tests: 2731 2732 make -C tools/testing/selftests TARGETS=livepatch run_tests 2733 2734 Alternatively, individual tests may be invoked: 2735 2736 tools/testing/selftests/livepatch/test-callbacks.sh 2737 tools/testing/selftests/livepatch/test-livepatch.sh 2738 tools/testing/selftests/livepatch/test-shadow-vars.sh 2739 2740 If unsure, say N. 2741 2742config TEST_OBJAGG 2743 tristate "Perform selftest on object aggreration manager" 2744 default n 2745 depends on OBJAGG 2746 help 2747 Enable this option to test object aggregation manager on boot 2748 (or module load). 2749 2750config TEST_MEMINIT 2751 tristate "Test heap/page initialization" 2752 help 2753 Test if the kernel is zero-initializing heap and page allocations. 2754 This can be useful to test init_on_alloc and init_on_free features. 2755 2756 If unsure, say N. 2757 2758config TEST_HMM 2759 tristate "Test HMM (Heterogeneous Memory Management)" 2760 depends on TRANSPARENT_HUGEPAGE 2761 depends on DEVICE_PRIVATE 2762 select HMM_MIRROR 2763 select MMU_NOTIFIER 2764 help 2765 This is a pseudo device driver solely for testing HMM. 2766 Say M here if you want to build the HMM test module. 2767 Doing so will allow you to run tools/testing/selftest/vm/hmm-tests. 2768 2769 If unsure, say N. 2770 2771config TEST_FREE_PAGES 2772 tristate "Test freeing pages" 2773 help 2774 Test that a memory leak does not occur due to a race between 2775 freeing a block of pages and a speculative page reference. 2776 Loading this module is safe if your kernel has the bug fixed. 2777 If the bug is not fixed, it will leak gigabytes of memory and 2778 probably OOM your system. 2779 2780config TEST_FPU 2781 tristate "Test floating point operations in kernel space" 2782 depends on X86 && !KCOV_INSTRUMENT_ALL 2783 help 2784 Enable this option to add /sys/kernel/debug/selftest_helpers/test_fpu 2785 which will trigger a sequence of floating point operations. This is used 2786 for self-testing floating point control register setting in 2787 kernel_fpu_begin(). 2788 2789 If unsure, say N. 2790 2791config TEST_CLOCKSOURCE_WATCHDOG 2792 tristate "Test clocksource watchdog in kernel space" 2793 depends on CLOCKSOURCE_WATCHDOG 2794 help 2795 Enable this option to create a kernel module that will trigger 2796 a test of the clocksource watchdog. This module may be loaded 2797 via modprobe or insmod in which case it will run upon being 2798 loaded, or it may be built in, in which case it will run 2799 shortly after boot. 2800 2801 If unsure, say N. 2802 2803endif # RUNTIME_TESTING_MENU 2804 2805config ARCH_USE_MEMTEST 2806 bool 2807 help 2808 An architecture should select this when it uses early_memtest() 2809 during boot process. 2810 2811config MEMTEST 2812 bool "Memtest" 2813 depends on ARCH_USE_MEMTEST 2814 help 2815 This option adds a kernel parameter 'memtest', which allows memtest 2816 to be set and executed. 2817 memtest=0, mean disabled; -- default 2818 memtest=1, mean do 1 test pattern; 2819 ... 2820 memtest=17, mean do 17 test patterns. 2821 If you are unsure how to answer this question, answer N. 2822 2823 2824 2825config HYPERV_TESTING 2826 bool "Microsoft Hyper-V driver testing" 2827 default n 2828 depends on HYPERV && DEBUG_FS 2829 help 2830 Select this option to enable Hyper-V vmbus testing. 2831 2832endmenu # "Kernel Testing and Coverage" 2833 2834menu "Rust hacking" 2835 2836config RUST_DEBUG_ASSERTIONS 2837 bool "Debug assertions" 2838 depends on RUST 2839 help 2840 Enables rustc's `-Cdebug-assertions` codegen option. 2841 2842 This flag lets you turn `cfg(debug_assertions)` conditional 2843 compilation on or off. This can be used to enable extra debugging 2844 code in development but not in production. For example, it controls 2845 the behavior of the standard library's `debug_assert!` macro. 2846 2847 Note that this will apply to all Rust code, including `core`. 2848 2849 If unsure, say N. 2850 2851config RUST_OVERFLOW_CHECKS 2852 bool "Overflow checks" 2853 default y 2854 depends on RUST 2855 help 2856 Enables rustc's `-Coverflow-checks` codegen option. 2857 2858 This flag allows you to control the behavior of runtime integer 2859 overflow. When overflow-checks are enabled, a Rust panic will occur 2860 on overflow. 2861 2862 Note that this will apply to all Rust code, including `core`. 2863 2864 If unsure, say Y. 2865 2866config RUST_BUILD_ASSERT_ALLOW 2867 bool "Allow unoptimized build-time assertions" 2868 depends on RUST 2869 help 2870 Controls how are `build_error!` and `build_assert!` handled during build. 2871 2872 If calls to them exist in the binary, it may indicate a violated invariant 2873 or that the optimizer failed to verify the invariant during compilation. 2874 2875 This should not happen, thus by default the build is aborted. However, 2876 as an escape hatch, you can choose Y here to ignore them during build 2877 and let the check be carried at runtime (with `panic!` being called if 2878 the check fails). 2879 2880 If unsure, say N. 2881 2882endmenu # "Rust" 2883 2884source "Documentation/Kconfig" 2885 2886endmenu # Kernel hacking 2887