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1# SPDX-License-Identifier: GPL-2.0-only
2menu "Kernel hacking"
3
4menu "printk and dmesg options"
5
6config PRINTK_TIME
7	bool "Show timing information on printks"
8	depends on PRINTK
9	help
10	  Selecting this option causes time stamps of the printk()
11	  messages to be added to the output of the syslog() system
12	  call and at the console.
13
14	  The timestamp is always recorded internally, and exported
15	  to /dev/kmsg. This flag just specifies if the timestamp should
16	  be included, not that the timestamp is recorded.
17
18	  The behavior is also controlled by the kernel command line
19	  parameter printk.time=1. See Documentation/admin-guide/kernel-parameters.rst
20
21config PRINTK_CALLER
22	bool "Show caller information on printks"
23	depends on PRINTK
24	help
25	  Selecting this option causes printk() to add a caller "thread id" (if
26	  in task context) or a caller "processor id" (if not in task context)
27	  to every message.
28
29	  This option is intended for environments where multiple threads
30	  concurrently call printk() for many times, for it is difficult to
31	  interpret without knowing where these lines (or sometimes individual
32	  line which was divided into multiple lines due to race) came from.
33
34	  Since toggling after boot makes the code racy, currently there is
35	  no option to enable/disable at the kernel command line parameter or
36	  sysfs interface.
37
38config CONSOLE_LOGLEVEL_DEFAULT
39	int "Default console loglevel (1-15)"
40	range 1 15
41	default "7"
42	help
43	  Default loglevel to determine what will be printed on the console.
44
45	  Setting a default here is equivalent to passing in loglevel=<x> in
46	  the kernel bootargs. loglevel=<x> continues to override whatever
47	  value is specified here as well.
48
49	  Note: This does not affect the log level of un-prefixed printk()
50	  usage in the kernel. That is controlled by the MESSAGE_LOGLEVEL_DEFAULT
51	  option.
52
53config CONSOLE_LOGLEVEL_QUIET
54	int "quiet console loglevel (1-15)"
55	range 1 15
56	default "4"
57	help
58	  loglevel to use when "quiet" is passed on the kernel commandline.
59
60	  When "quiet" is passed on the kernel commandline this loglevel
61	  will be used as the loglevel. IOW passing "quiet" will be the
62	  equivalent of passing "loglevel=<CONSOLE_LOGLEVEL_QUIET>"
63
64config MESSAGE_LOGLEVEL_DEFAULT
65	int "Default message log level (1-7)"
66	range 1 7
67	default "4"
68	help
69	  Default log level for printk statements with no specified priority.
70
71	  This was hard-coded to KERN_WARNING since at least 2.6.10 but folks
72	  that are auditing their logs closely may want to set it to a lower
73	  priority.
74
75	  Note: This does not affect what message level gets printed on the console
76	  by default. To change that, use loglevel=<x> in the kernel bootargs,
77	  or pick a different CONSOLE_LOGLEVEL_DEFAULT configuration value.
78
79config BOOT_PRINTK_DELAY
80	bool "Delay each boot printk message by N milliseconds"
81	depends on DEBUG_KERNEL && PRINTK && GENERIC_CALIBRATE_DELAY
82	help
83	  This build option allows you to read kernel boot messages
84	  by inserting a short delay after each one.  The delay is
85	  specified in milliseconds on the kernel command line,
86	  using "boot_delay=N".
87
88	  It is likely that you would also need to use "lpj=M" to preset
89	  the "loops per jiffie" value.
90	  See a previous boot log for the "lpj" value to use for your
91	  system, and then set "lpj=M" before setting "boot_delay=N".
92	  NOTE:  Using this option may adversely affect SMP systems.
93	  I.e., processors other than the first one may not boot up.
94	  BOOT_PRINTK_DELAY also may cause LOCKUP_DETECTOR to detect
95	  what it believes to be lockup conditions.
96
97config DYNAMIC_DEBUG
98	bool "Enable dynamic printk() support"
99	default n
100	depends on PRINTK
101	depends on (DEBUG_FS || PROC_FS)
102	select DYNAMIC_DEBUG_CORE
103	help
104
105	  Compiles debug level messages into the kernel, which would not
106	  otherwise be available at runtime. These messages can then be
107	  enabled/disabled based on various levels of scope - per source file,
108	  function, module, format string, and line number. This mechanism
109	  implicitly compiles in all pr_debug() and dev_dbg() calls, which
110	  enlarges the kernel text size by about 2%.
111
112	  If a source file is compiled with DEBUG flag set, any
113	  pr_debug() calls in it are enabled by default, but can be
114	  disabled at runtime as below.  Note that DEBUG flag is
115	  turned on by many CONFIG_*DEBUG* options.
116
117	  Usage:
118
119	  Dynamic debugging is controlled via the 'dynamic_debug/control' file,
120	  which is contained in the 'debugfs' filesystem or procfs.
121	  Thus, the debugfs or procfs filesystem must first be mounted before
122	  making use of this feature.
123	  We refer the control file as: <debugfs>/dynamic_debug/control. This
124	  file contains a list of the debug statements that can be enabled. The
125	  format for each line of the file is:
126
127		filename:lineno [module]function flags format
128
129	  filename : source file of the debug statement
130	  lineno : line number of the debug statement
131	  module : module that contains the debug statement
132	  function : function that contains the debug statement
133	  flags : '=p' means the line is turned 'on' for printing
134	  format : the format used for the debug statement
135
136	  From a live system:
137
138		nullarbor:~ # cat <debugfs>/dynamic_debug/control
139		# filename:lineno [module]function flags format
140		fs/aio.c:222 [aio]__put_ioctx =_ "__put_ioctx:\040freeing\040%p\012"
141		fs/aio.c:248 [aio]ioctx_alloc =_ "ENOMEM:\040nr_events\040too\040high\012"
142		fs/aio.c:1770 [aio]sys_io_cancel =_ "calling\040cancel\012"
143
144	  Example usage:
145
146		// enable the message at line 1603 of file svcsock.c
147		nullarbor:~ # echo -n 'file svcsock.c line 1603 +p' >
148						<debugfs>/dynamic_debug/control
149
150		// enable all the messages in file svcsock.c
151		nullarbor:~ # echo -n 'file svcsock.c +p' >
152						<debugfs>/dynamic_debug/control
153
154		// enable all the messages in the NFS server module
155		nullarbor:~ # echo -n 'module nfsd +p' >
156						<debugfs>/dynamic_debug/control
157
158		// enable all 12 messages in the function svc_process()
159		nullarbor:~ # echo -n 'func svc_process +p' >
160						<debugfs>/dynamic_debug/control
161
162		// disable all 12 messages in the function svc_process()
163		nullarbor:~ # echo -n 'func svc_process -p' >
164						<debugfs>/dynamic_debug/control
165
166	  See Documentation/admin-guide/dynamic-debug-howto.rst for additional
167	  information.
168
169config DYNAMIC_DEBUG_CORE
170	bool "Enable core function of dynamic debug support"
171	depends on PRINTK
172	depends on (DEBUG_FS || PROC_FS)
173	help
174	  Enable core functional support of dynamic debug. It is useful
175	  when you want to tie dynamic debug to your kernel modules with
176	  DYNAMIC_DEBUG_MODULE defined for each of them, especially for
177	  the case of embedded system where the kernel image size is
178	  sensitive for people.
179
180config SYMBOLIC_ERRNAME
181	bool "Support symbolic error names in printf"
182	default y if PRINTK
183	help
184	  If you say Y here, the kernel's printf implementation will
185	  be able to print symbolic error names such as ENOSPC instead
186	  of the number 28. It makes the kernel image slightly larger
187	  (about 3KB), but can make the kernel logs easier to read.
188
189config DEBUG_BUGVERBOSE
190	bool "Verbose BUG() reporting (adds 70K)" if DEBUG_KERNEL && EXPERT
191	depends on BUG && (GENERIC_BUG || HAVE_DEBUG_BUGVERBOSE)
192	default y
193	help
194	  Say Y here to make BUG() panics output the file name and line number
195	  of the BUG call as well as the EIP and oops trace.  This aids
196	  debugging but costs about 70-100K of memory.
197
198endmenu # "printk and dmesg options"
199
200menu "Compile-time checks and compiler options"
201
202config DEBUG_INFO
203	bool "Compile the kernel with debug info"
204	depends on DEBUG_KERNEL && !COMPILE_TEST
205	help
206	  If you say Y here the resulting kernel image will include
207	  debugging info resulting in a larger kernel image.
208	  This adds debug symbols to the kernel and modules (gcc -g), and
209	  is needed if you intend to use kernel crashdump or binary object
210	  tools like crash, kgdb, LKCD, gdb, etc on the kernel.
211	  Say Y here only if you plan to debug the kernel.
212
213	  If unsure, say N.
214
215if DEBUG_INFO
216
217config DEBUG_INFO_REDUCED
218	bool "Reduce debugging information"
219	help
220	  If you say Y here gcc is instructed to generate less debugging
221	  information for structure types. This means that tools that
222	  need full debugging information (like kgdb or systemtap) won't
223	  be happy. But if you merely need debugging information to
224	  resolve line numbers there is no loss. Advantage is that
225	  build directory object sizes shrink dramatically over a full
226	  DEBUG_INFO build and compile times are reduced too.
227	  Only works with newer gcc versions.
228
229config DEBUG_INFO_COMPRESSED
230	bool "Compressed debugging information"
231	depends on $(cc-option,-gz=zlib)
232	depends on $(ld-option,--compress-debug-sections=zlib)
233	help
234	  Compress the debug information using zlib.  Requires GCC 5.0+ or Clang
235	  5.0+, binutils 2.26+, and zlib.
236
237	  Users of dpkg-deb via scripts/package/builddeb may find an increase in
238	  size of their debug .deb packages with this config set, due to the
239	  debug info being compressed with zlib, then the object files being
240	  recompressed with a different compression scheme. But this is still
241	  preferable to setting $KDEB_COMPRESS to "none" which would be even
242	  larger.
243
244config DEBUG_INFO_SPLIT
245	bool "Produce split debuginfo in .dwo files"
246	depends on $(cc-option,-gsplit-dwarf)
247	help
248	  Generate debug info into separate .dwo files. This significantly
249	  reduces the build directory size for builds with DEBUG_INFO,
250	  because it stores the information only once on disk in .dwo
251	  files instead of multiple times in object files and executables.
252	  In addition the debug information is also compressed.
253
254	  Requires recent gcc (4.7+) and recent gdb/binutils.
255	  Any tool that packages or reads debug information would need
256	  to know about the .dwo files and include them.
257	  Incompatible with older versions of ccache.
258
259config DEBUG_INFO_DWARF4
260	bool "Generate dwarf4 debuginfo"
261	depends on $(cc-option,-gdwarf-4)
262	help
263	  Generate dwarf4 debug info. This requires recent versions
264	  of gcc and gdb. It makes the debug information larger.
265	  But it significantly improves the success of resolving
266	  variables in gdb on optimized code.
267
268config DEBUG_INFO_BTF
269	bool "Generate BTF typeinfo"
270	depends on !DEBUG_INFO_SPLIT && !DEBUG_INFO_REDUCED
271	depends on !GCC_PLUGIN_RANDSTRUCT || COMPILE_TEST
272	help
273	  Generate deduplicated BTF type information from DWARF debug info.
274	  Turning this on expects presence of pahole tool, which will convert
275	  DWARF type info into equivalent deduplicated BTF type info.
276
277config GDB_SCRIPTS
278	bool "Provide GDB scripts for kernel debugging"
279	help
280	  This creates the required links to GDB helper scripts in the
281	  build directory. If you load vmlinux into gdb, the helper
282	  scripts will be automatically imported by gdb as well, and
283	  additional functions are available to analyze a Linux kernel
284	  instance. See Documentation/dev-tools/gdb-kernel-debugging.rst
285	  for further details.
286
287endif # DEBUG_INFO
288
289config ENABLE_MUST_CHECK
290	bool "Enable __must_check logic"
291	default y
292	help
293	  Enable the __must_check logic in the kernel build.  Disable this to
294	  suppress the "warning: ignoring return value of 'foo', declared with
295	  attribute warn_unused_result" messages.
296
297config FRAME_WARN
298	int "Warn for stack frames larger than"
299	range 0 8192
300	default 2048 if GCC_PLUGIN_LATENT_ENTROPY
301	default 2048 if PARISC
302	default 1536 if (!64BIT && XTENSA)
303	default 1280 if KASAN && !64BIT
304	default 1024 if !64BIT
305	default 2048 if 64BIT
306	help
307	  Tell gcc to warn at build time for stack frames larger than this.
308	  Setting this too low will cause a lot of warnings.
309	  Setting it to 0 disables the warning.
310
311config STRIP_ASM_SYMS
312	bool "Strip assembler-generated symbols during link"
313	default n
314	help
315	  Strip internal assembler-generated symbols during a link (symbols
316	  that look like '.Lxxx') so they don't pollute the output of
317	  get_wchan() and suchlike.
318
319config READABLE_ASM
320	bool "Generate readable assembler code"
321	depends on DEBUG_KERNEL
322	help
323	  Disable some compiler optimizations that tend to generate human unreadable
324	  assembler output. This may make the kernel slightly slower, but it helps
325	  to keep kernel developers who have to stare a lot at assembler listings
326	  sane.
327
328config HEADERS_INSTALL
329	bool "Install uapi headers to usr/include"
330	depends on !UML
331	help
332	  This option will install uapi headers (headers exported to user-space)
333	  into the usr/include directory for use during the kernel build.
334	  This is unneeded for building the kernel itself, but needed for some
335	  user-space program samples. It is also needed by some features such
336	  as uapi header sanity checks.
337
338config DEBUG_SECTION_MISMATCH
339	bool "Enable full Section mismatch analysis"
340	help
341	  The section mismatch analysis checks if there are illegal
342	  references from one section to another section.
343	  During linktime or runtime, some sections are dropped;
344	  any use of code/data previously in these sections would
345	  most likely result in an oops.
346	  In the code, functions and variables are annotated with
347	  __init,, etc. (see the full list in include/linux/init.h),
348	  which results in the code/data being placed in specific sections.
349	  The section mismatch analysis is always performed after a full
350	  kernel build, and enabling this option causes the following
351	  additional step to occur:
352	  - Add the option -fno-inline-functions-called-once to gcc commands.
353	    When inlining a function annotated with __init in a non-init
354	    function, we would lose the section information and thus
355	    the analysis would not catch the illegal reference.
356	    This option tells gcc to inline less (but it does result in
357	    a larger kernel).
358
359config SECTION_MISMATCH_WARN_ONLY
360	bool "Make section mismatch errors non-fatal"
361	default y
362	help
363	  If you say N here, the build process will fail if there are any
364	  section mismatch, instead of just throwing warnings.
365
366	  If unsure, say Y.
367
368config DEBUG_FORCE_FUNCTION_ALIGN_32B
369	bool "Force all function address 32B aligned" if EXPERT
370	help
371	  There are cases that a commit from one domain changes the function
372	  address alignment of other domains, and cause magic performance
373	  bump (regression or improvement). Enable this option will help to
374	  verify if the bump is caused by function alignment changes, while
375	  it will slightly increase the kernel size and affect icache usage.
376
377	  It is mainly for debug and performance tuning use.
378
379#
380# Select this config option from the architecture Kconfig, if it
381# is preferred to always offer frame pointers as a config
382# option on the architecture (regardless of KERNEL_DEBUG):
383#
384config ARCH_WANT_FRAME_POINTERS
385	bool
386
387config FRAME_POINTER
388	bool "Compile the kernel with frame pointers"
389	depends on DEBUG_KERNEL && (M68K || UML || SUPERH) || ARCH_WANT_FRAME_POINTERS
390	default y if (DEBUG_INFO && UML) || ARCH_WANT_FRAME_POINTERS
391	help
392	  If you say Y here the resulting kernel image will be slightly
393	  larger and slower, but it gives very useful debugging information
394	  in case of kernel bugs. (precise oopses/stacktraces/warnings)
395
396config STACK_VALIDATION
397	bool "Compile-time stack metadata validation"
398	depends on HAVE_STACK_VALIDATION
399	default n
400	help
401	  Add compile-time checks to validate stack metadata, including frame
402	  pointers (if CONFIG_FRAME_POINTER is enabled).  This helps ensure
403	  that runtime stack traces are more reliable.
404
405	  This is also a prerequisite for generation of ORC unwind data, which
406	  is needed for CONFIG_UNWINDER_ORC.
407
408	  For more information, see
409	  tools/objtool/Documentation/stack-validation.txt.
410
411config VMLINUX_VALIDATION
412	bool
413	depends on STACK_VALIDATION && DEBUG_ENTRY && !PARAVIRT
414	default y
415
416config DEBUG_FORCE_WEAK_PER_CPU
417	bool "Force weak per-cpu definitions"
418	depends on DEBUG_KERNEL
419	help
420	  s390 and alpha require percpu variables in modules to be
421	  defined weak to work around addressing range issue which
422	  puts the following two restrictions on percpu variable
423	  definitions.
424
425	  1. percpu symbols must be unique whether static or not
426	  2. percpu variables can't be defined inside a function
427
428	  To ensure that generic code follows the above rules, this
429	  option forces all percpu variables to be defined as weak.
430
431endmenu # "Compiler options"
432
433menu "Generic Kernel Debugging Instruments"
434
435config MAGIC_SYSRQ
436	bool "Magic SysRq key"
437	depends on !UML
438	help
439	  If you say Y here, you will have some control over the system even
440	  if the system crashes for example during kernel debugging (e.g., you
441	  will be able to flush the buffer cache to disk, reboot the system
442	  immediately or dump some status information). This is accomplished
443	  by pressing various keys while holding SysRq (Alt+PrintScreen). It
444	  also works on a serial console (on PC hardware at least), if you
445	  send a BREAK and then within 5 seconds a command keypress. The
446	  keys are documented in <file:Documentation/admin-guide/sysrq.rst>.
447	  Don't say Y unless you really know what this hack does.
448
449config MAGIC_SYSRQ_DEFAULT_ENABLE
450	hex "Enable magic SysRq key functions by default"
451	depends on MAGIC_SYSRQ
452	default 0x1
453	help
454	  Specifies which SysRq key functions are enabled by default.
455	  This may be set to 1 or 0 to enable or disable them all, or
456	  to a bitmask as described in Documentation/admin-guide/sysrq.rst.
457
458config MAGIC_SYSRQ_SERIAL
459	bool "Enable magic SysRq key over serial"
460	depends on MAGIC_SYSRQ
461	default y
462	help
463	  Many embedded boards have a disconnected TTL level serial which can
464	  generate some garbage that can lead to spurious false sysrq detects.
465	  This option allows you to decide whether you want to enable the
466	  magic SysRq key.
467
468config MAGIC_SYSRQ_SERIAL_SEQUENCE
469	string "Char sequence that enables magic SysRq over serial"
470	depends on MAGIC_SYSRQ_SERIAL
471	default ""
472	help
473	  Specifies a sequence of characters that can follow BREAK to enable
474	  SysRq on a serial console.
475
476	  If unsure, leave an empty string and the option will not be enabled.
477
478config DEBUG_FS
479	bool "Debug Filesystem"
480	help
481	  debugfs is a virtual file system that kernel developers use to put
482	  debugging files into.  Enable this option to be able to read and
483	  write to these files.
484
485	  For detailed documentation on the debugfs API, see
486	  Documentation/filesystems/.
487
488	  If unsure, say N.
489
490choice
491	prompt "Debugfs default access"
492	depends on DEBUG_FS
493	default DEBUG_FS_ALLOW_ALL
494	help
495	  This selects the default access restrictions for debugfs.
496	  It can be overridden with kernel command line option
497	  debugfs=[on,no-mount,off]. The restrictions apply for API access
498	  and filesystem registration.
499
500config DEBUG_FS_ALLOW_ALL
501	bool "Access normal"
502	help
503	  No restrictions apply. Both API and filesystem registration
504	  is on. This is the normal default operation.
505
506config DEBUG_FS_DISALLOW_MOUNT
507	bool "Do not register debugfs as filesystem"
508	help
509	  The API is open but filesystem is not loaded. Clients can still do
510	  their work and read with debug tools that do not need
511	  debugfs filesystem.
512
513config DEBUG_FS_ALLOW_NONE
514	bool "No access"
515	help
516	  Access is off. Clients get -PERM when trying to create nodes in
517	  debugfs tree and debugfs is not registered as a filesystem.
518	  Client can then back-off or continue without debugfs access.
519
520endchoice
521
522source "lib/Kconfig.kgdb"
523source "lib/Kconfig.ubsan"
524source "lib/Kconfig.kcsan"
525
526endmenu
527
528config DEBUG_KERNEL
529	bool "Kernel debugging"
530	help
531	  Say Y here if you are developing drivers or trying to debug and
532	  identify kernel problems.
533
534config DEBUG_MISC
535	bool "Miscellaneous debug code"
536	default DEBUG_KERNEL
537	depends on DEBUG_KERNEL
538	help
539	  Say Y here if you need to enable miscellaneous debug code that should
540	  be under a more specific debug option but isn't.
541
542
543menu "Memory Debugging"
544
545source "mm/Kconfig.debug"
546
547config DEBUG_OBJECTS
548	bool "Debug object operations"
549	depends on DEBUG_KERNEL
550	help
551	  If you say Y here, additional code will be inserted into the
552	  kernel to track the life time of various objects and validate
553	  the operations on those objects.
554
555config DEBUG_OBJECTS_SELFTEST
556	bool "Debug objects selftest"
557	depends on DEBUG_OBJECTS
558	help
559	  This enables the selftest of the object debug code.
560
561config DEBUG_OBJECTS_FREE
562	bool "Debug objects in freed memory"
563	depends on DEBUG_OBJECTS
564	help
565	  This enables checks whether a k/v free operation frees an area
566	  which contains an object which has not been deactivated
567	  properly. This can make kmalloc/kfree-intensive workloads
568	  much slower.
569
570config DEBUG_OBJECTS_TIMERS
571	bool "Debug timer objects"
572	depends on DEBUG_OBJECTS
573	help
574	  If you say Y here, additional code will be inserted into the
575	  timer routines to track the life time of timer objects and
576	  validate the timer operations.
577
578config DEBUG_OBJECTS_WORK
579	bool "Debug work objects"
580	depends on DEBUG_OBJECTS
581	help
582	  If you say Y here, additional code will be inserted into the
583	  work queue routines to track the life time of work objects and
584	  validate the work operations.
585
586config DEBUG_OBJECTS_RCU_HEAD
587	bool "Debug RCU callbacks objects"
588	depends on DEBUG_OBJECTS
589	help
590	  Enable this to turn on debugging of RCU list heads (call_rcu() usage).
591
592config DEBUG_OBJECTS_PERCPU_COUNTER
593	bool "Debug percpu counter objects"
594	depends on DEBUG_OBJECTS
595	help
596	  If you say Y here, additional code will be inserted into the
597	  percpu counter routines to track the life time of percpu counter
598	  objects and validate the percpu counter operations.
599
600config DEBUG_OBJECTS_ENABLE_DEFAULT
601	int "debug_objects bootup default value (0-1)"
602	range 0 1
603	default "1"
604	depends on DEBUG_OBJECTS
605	help
606	  Debug objects boot parameter default value
607
608config DEBUG_SLAB
609	bool "Debug slab memory allocations"
610	depends on DEBUG_KERNEL && SLAB
611	help
612	  Say Y here to have the kernel do limited verification on memory
613	  allocation as well as poisoning memory on free to catch use of freed
614	  memory. This can make kmalloc/kfree-intensive workloads much slower.
615
616config SLUB_DEBUG_ON
617	bool "SLUB debugging on by default"
618	depends on SLUB && SLUB_DEBUG
619	default n
620	help
621	  Boot with debugging on by default. SLUB boots by default with
622	  the runtime debug capabilities switched off. Enabling this is
623	  equivalent to specifying the "slub_debug" parameter on boot.
624	  There is no support for more fine grained debug control like
625	  possible with slub_debug=xxx. SLUB debugging may be switched
626	  off in a kernel built with CONFIG_SLUB_DEBUG_ON by specifying
627	  "slub_debug=-".
628
629config SLUB_STATS
630	default n
631	bool "Enable SLUB performance statistics"
632	depends on SLUB && SYSFS
633	help
634	  SLUB statistics are useful to debug SLUBs allocation behavior in
635	  order find ways to optimize the allocator. This should never be
636	  enabled for production use since keeping statistics slows down
637	  the allocator by a few percentage points. The slabinfo command
638	  supports the determination of the most active slabs to figure
639	  out which slabs are relevant to a particular load.
640	  Try running: slabinfo -DA
641
642config HAVE_DEBUG_KMEMLEAK
643	bool
644
645config DEBUG_KMEMLEAK
646	bool "Kernel memory leak detector"
647	depends on DEBUG_KERNEL && HAVE_DEBUG_KMEMLEAK
648	select DEBUG_FS
649	select STACKTRACE if STACKTRACE_SUPPORT
650	select KALLSYMS
651	select CRC32
652	help
653	  Say Y here if you want to enable the memory leak
654	  detector. The memory allocation/freeing is traced in a way
655	  similar to the Boehm's conservative garbage collector, the
656	  difference being that the orphan objects are not freed but
657	  only shown in /sys/kernel/debug/kmemleak. Enabling this
658	  feature will introduce an overhead to memory
659	  allocations. See Documentation/dev-tools/kmemleak.rst for more
660	  details.
661
662	  Enabling DEBUG_SLAB or SLUB_DEBUG may increase the chances
663	  of finding leaks due to the slab objects poisoning.
664
665	  In order to access the kmemleak file, debugfs needs to be
666	  mounted (usually at /sys/kernel/debug).
667
668config DEBUG_KMEMLEAK_MEM_POOL_SIZE
669	int "Kmemleak memory pool size"
670	depends on DEBUG_KMEMLEAK
671	range 200 1000000
672	default 16000
673	help
674	  Kmemleak must track all the memory allocations to avoid
675	  reporting false positives. Since memory may be allocated or
676	  freed before kmemleak is fully initialised, use a static pool
677	  of metadata objects to track such callbacks. After kmemleak is
678	  fully initialised, this memory pool acts as an emergency one
679	  if slab allocations fail.
680
681config DEBUG_KMEMLEAK_TEST
682	tristate "Simple test for the kernel memory leak detector"
683	depends on DEBUG_KMEMLEAK && m
684	help
685	  This option enables a module that explicitly leaks memory.
686
687	  If unsure, say N.
688
689config DEBUG_KMEMLEAK_DEFAULT_OFF
690	bool "Default kmemleak to off"
691	depends on DEBUG_KMEMLEAK
692	help
693	  Say Y here to disable kmemleak by default. It can then be enabled
694	  on the command line via kmemleak=on.
695
696config DEBUG_KMEMLEAK_AUTO_SCAN
697	bool "Enable kmemleak auto scan thread on boot up"
698	default y
699	depends on DEBUG_KMEMLEAK
700	help
701	  Depending on the cpu, kmemleak scan may be cpu intensive and can
702	  stall user tasks at times. This option enables/disables automatic
703	  kmemleak scan at boot up.
704
705	  Say N here to disable kmemleak auto scan thread to stop automatic
706	  scanning. Disabling this option disables automatic reporting of
707	  memory leaks.
708
709	  If unsure, say Y.
710
711config DEBUG_STACK_USAGE
712	bool "Stack utilization instrumentation"
713	depends on DEBUG_KERNEL && !IA64
714	help
715	  Enables the display of the minimum amount of free stack which each
716	  task has ever had available in the sysrq-T and sysrq-P debug output.
717
718	  This option will slow down process creation somewhat.
719
720config SCHED_STACK_END_CHECK
721	bool "Detect stack corruption on calls to schedule()"
722	depends on DEBUG_KERNEL
723	default n
724	help
725	  This option checks for a stack overrun on calls to schedule().
726	  If the stack end location is found to be over written always panic as
727	  the content of the corrupted region can no longer be trusted.
728	  This is to ensure no erroneous behaviour occurs which could result in
729	  data corruption or a sporadic crash at a later stage once the region
730	  is examined. The runtime overhead introduced is minimal.
731
732config ARCH_HAS_DEBUG_VM_PGTABLE
733	bool
734	help
735	  An architecture should select this when it can successfully
736	  build and run DEBUG_VM_PGTABLE.
737
738config DEBUG_VM
739	bool "Debug VM"
740	depends on DEBUG_KERNEL
741	help
742	  Enable this to turn on extended checks in the virtual-memory system
743	  that may impact performance.
744
745	  If unsure, say N.
746
747config DEBUG_VM_VMACACHE
748	bool "Debug VMA caching"
749	depends on DEBUG_VM
750	help
751	  Enable this to turn on VMA caching debug information. Doing so
752	  can cause significant overhead, so only enable it in non-production
753	  environments.
754
755	  If unsure, say N.
756
757config DEBUG_VM_RB
758	bool "Debug VM red-black trees"
759	depends on DEBUG_VM
760	help
761	  Enable VM red-black tree debugging information and extra validations.
762
763	  If unsure, say N.
764
765config DEBUG_VM_PGFLAGS
766	bool "Debug page-flags operations"
767	depends on DEBUG_VM
768	help
769	  Enables extra validation on page flags operations.
770
771	  If unsure, say N.
772
773config DEBUG_VM_PGTABLE
774	bool "Debug arch page table for semantics compliance"
775	depends on MMU
776	depends on ARCH_HAS_DEBUG_VM_PGTABLE
777	default y if DEBUG_VM
778	help
779	  This option provides a debug method which can be used to test
780	  architecture page table helper functions on various platforms in
781	  verifying if they comply with expected generic MM semantics. This
782	  will help architecture code in making sure that any changes or
783	  new additions of these helpers still conform to expected
784	  semantics of the generic MM. Platforms will have to opt in for
785	  this through ARCH_HAS_DEBUG_VM_PGTABLE.
786
787	  If unsure, say N.
788
789config ARCH_HAS_DEBUG_VIRTUAL
790	bool
791
792config DEBUG_VIRTUAL
793	bool "Debug VM translations"
794	depends on DEBUG_KERNEL && ARCH_HAS_DEBUG_VIRTUAL
795	help
796	  Enable some costly sanity checks in virtual to page code. This can
797	  catch mistakes with virt_to_page() and friends.
798
799	  If unsure, say N.
800
801config DEBUG_NOMMU_REGIONS
802	bool "Debug the global anon/private NOMMU mapping region tree"
803	depends on DEBUG_KERNEL && !MMU
804	help
805	  This option causes the global tree of anonymous and private mapping
806	  regions to be regularly checked for invalid topology.
807
808config DEBUG_MEMORY_INIT
809	bool "Debug memory initialisation" if EXPERT
810	default !EXPERT
811	help
812	  Enable this for additional checks during memory initialisation.
813	  The sanity checks verify aspects of the VM such as the memory model
814	  and other information provided by the architecture. Verbose
815	  information will be printed at KERN_DEBUG loglevel depending
816	  on the mminit_loglevel= command-line option.
817
818	  If unsure, say Y
819
820config MEMORY_NOTIFIER_ERROR_INJECT
821	tristate "Memory hotplug notifier error injection module"
822	depends on MEMORY_HOTPLUG_SPARSE && NOTIFIER_ERROR_INJECTION
823	help
824	  This option provides the ability to inject artificial errors to
825	  memory hotplug notifier chain callbacks.  It is controlled through
826	  debugfs interface under /sys/kernel/debug/notifier-error-inject/memory
827
828	  If the notifier call chain should be failed with some events
829	  notified, write the error code to "actions/<notifier event>/error".
830
831	  Example: Inject memory hotplug offline error (-12 == -ENOMEM)
832
833	  # cd /sys/kernel/debug/notifier-error-inject/memory
834	  # echo -12 > actions/MEM_GOING_OFFLINE/error
835	  # echo offline > /sys/devices/system/memory/memoryXXX/state
836	  bash: echo: write error: Cannot allocate memory
837
838	  To compile this code as a module, choose M here: the module will
839	  be called memory-notifier-error-inject.
840
841	  If unsure, say N.
842
843config DEBUG_PER_CPU_MAPS
844	bool "Debug access to per_cpu maps"
845	depends on DEBUG_KERNEL
846	depends on SMP
847	help
848	  Say Y to verify that the per_cpu map being accessed has
849	  been set up. This adds a fair amount of code to kernel memory
850	  and decreases performance.
851
852	  Say N if unsure.
853
854config DEBUG_HIGHMEM
855	bool "Highmem debugging"
856	depends on DEBUG_KERNEL && HIGHMEM
857	help
858	  This option enables additional error checking for high memory
859	  systems.  Disable for production systems.
860
861config HAVE_DEBUG_STACKOVERFLOW
862	bool
863
864config DEBUG_STACKOVERFLOW
865	bool "Check for stack overflows"
866	depends on DEBUG_KERNEL && HAVE_DEBUG_STACKOVERFLOW
867	help
868	  Say Y here if you want to check for overflows of kernel, IRQ
869	  and exception stacks (if your architecture uses them). This
870	  option will show detailed messages if free stack space drops
871	  below a certain limit.
872
873	  These kinds of bugs usually occur when call-chains in the
874	  kernel get too deep, especially when interrupts are
875	  involved.
876
877	  Use this in cases where you see apparently random memory
878	  corruption, especially if it appears in 'struct thread_info'
879
880	  If in doubt, say "N".
881
882source "lib/Kconfig.kasan"
883
884endmenu # "Memory Debugging"
885
886config DEBUG_SHIRQ
887	bool "Debug shared IRQ handlers"
888	depends on DEBUG_KERNEL
889	help
890	  Enable this to generate a spurious interrupt just before a shared
891	  interrupt handler is deregistered (generating one when registering
892	  is currently disabled). Drivers need to handle this correctly. Some
893	  don't and need to be caught.
894
895menu "Debug Oops, Lockups and Hangs"
896
897config PANIC_ON_OOPS
898	bool "Panic on Oops"
899	help
900	  Say Y here to enable the kernel to panic when it oopses. This
901	  has the same effect as setting oops=panic on the kernel command
902	  line.
903
904	  This feature is useful to ensure that the kernel does not do
905	  anything erroneous after an oops which could result in data
906	  corruption or other issues.
907
908	  Say N if unsure.
909
910config PANIC_ON_OOPS_VALUE
911	int
912	range 0 1
913	default 0 if !PANIC_ON_OOPS
914	default 1 if PANIC_ON_OOPS
915
916config PANIC_TIMEOUT
917	int "panic timeout"
918	default 0
919	help
920	  Set the timeout value (in seconds) until a reboot occurs when
921	  the kernel panics. If n = 0, then we wait forever. A timeout
922	  value n > 0 will wait n seconds before rebooting, while a timeout
923	  value n < 0 will reboot immediately.
924
925config LOCKUP_DETECTOR
926	bool
927
928config SOFTLOCKUP_DETECTOR
929	bool "Detect Soft Lockups"
930	depends on DEBUG_KERNEL && !S390
931	select LOCKUP_DETECTOR
932	help
933	  Say Y here to enable the kernel to act as a watchdog to detect
934	  soft lockups.
935
936	  Softlockups are bugs that cause the kernel to loop in kernel
937	  mode for more than 20 seconds, without giving other tasks a
938	  chance to run.  The current stack trace is displayed upon
939	  detection and the system will stay locked up.
940
941config BOOTPARAM_SOFTLOCKUP_PANIC
942	bool "Panic (Reboot) On Soft Lockups"
943	depends on SOFTLOCKUP_DETECTOR
944	help
945	  Say Y here to enable the kernel to panic on "soft lockups",
946	  which are bugs that cause the kernel to loop in kernel
947	  mode for more than 20 seconds (configurable using the watchdog_thresh
948	  sysctl), without giving other tasks a chance to run.
949
950	  The panic can be used in combination with panic_timeout,
951	  to cause the system to reboot automatically after a
952	  lockup has been detected. This feature is useful for
953	  high-availability systems that have uptime guarantees and
954	  where a lockup must be resolved ASAP.
955
956	  Say N if unsure.
957
958config BOOTPARAM_SOFTLOCKUP_PANIC_VALUE
959	int
960	depends on SOFTLOCKUP_DETECTOR
961	range 0 1
962	default 0 if !BOOTPARAM_SOFTLOCKUP_PANIC
963	default 1 if BOOTPARAM_SOFTLOCKUP_PANIC
964
965config HARDLOCKUP_DETECTOR_PERF
966	bool
967	select SOFTLOCKUP_DETECTOR
968
969#
970# Enables a timestamp based low pass filter to compensate for perf based
971# hard lockup detection which runs too fast due to turbo modes.
972#
973config HARDLOCKUP_CHECK_TIMESTAMP
974	bool
975
976#
977# arch/ can define HAVE_HARDLOCKUP_DETECTOR_ARCH to provide their own hard
978# lockup detector rather than the perf based detector.
979#
980config HARDLOCKUP_DETECTOR
981	bool "Detect Hard Lockups"
982	depends on DEBUG_KERNEL && !S390
983	depends on HAVE_HARDLOCKUP_DETECTOR_PERF || HAVE_HARDLOCKUP_DETECTOR_ARCH
984	select LOCKUP_DETECTOR
985	select HARDLOCKUP_DETECTOR_PERF if HAVE_HARDLOCKUP_DETECTOR_PERF
986	help
987	  Say Y here to enable the kernel to act as a watchdog to detect
988	  hard lockups.
989
990	  Hardlockups are bugs that cause the CPU to loop in kernel mode
991	  for more than 10 seconds, without letting other interrupts have a
992	  chance to run.  The current stack trace is displayed upon detection
993	  and the system will stay locked up.
994
995config BOOTPARAM_HARDLOCKUP_PANIC
996	bool "Panic (Reboot) On Hard Lockups"
997	depends on HARDLOCKUP_DETECTOR
998	help
999	  Say Y here to enable the kernel to panic on "hard lockups",
1000	  which are bugs that cause the kernel to loop in kernel
1001	  mode with interrupts disabled for more than 10 seconds (configurable
1002	  using the watchdog_thresh sysctl).
1003
1004	  Say N if unsure.
1005
1006config BOOTPARAM_HARDLOCKUP_PANIC_VALUE
1007	int
1008	depends on HARDLOCKUP_DETECTOR
1009	range 0 1
1010	default 0 if !BOOTPARAM_HARDLOCKUP_PANIC
1011	default 1 if BOOTPARAM_HARDLOCKUP_PANIC
1012
1013config DETECT_HUNG_TASK
1014	bool "Detect Hung Tasks"
1015	depends on DEBUG_KERNEL
1016	default SOFTLOCKUP_DETECTOR
1017	help
1018	  Say Y here to enable the kernel to detect "hung tasks",
1019	  which are bugs that cause the task to be stuck in
1020	  uninterruptible "D" state indefinitely.
1021
1022	  When a hung task is detected, the kernel will print the
1023	  current stack trace (which you should report), but the
1024	  task will stay in uninterruptible state. If lockdep is
1025	  enabled then all held locks will also be reported. This
1026	  feature has negligible overhead.
1027
1028config DEFAULT_HUNG_TASK_TIMEOUT
1029	int "Default timeout for hung task detection (in seconds)"
1030	depends on DETECT_HUNG_TASK
1031	default 120
1032	help
1033	  This option controls the default timeout (in seconds) used
1034	  to determine when a task has become non-responsive and should
1035	  be considered hung.
1036
1037	  It can be adjusted at runtime via the kernel.hung_task_timeout_secs
1038	  sysctl or by writing a value to
1039	  /proc/sys/kernel/hung_task_timeout_secs.
1040
1041	  A timeout of 0 disables the check.  The default is two minutes.
1042	  Keeping the default should be fine in most cases.
1043
1044config BOOTPARAM_HUNG_TASK_PANIC
1045	bool "Panic (Reboot) On Hung Tasks"
1046	depends on DETECT_HUNG_TASK
1047	help
1048	  Say Y here to enable the kernel to panic on "hung tasks",
1049	  which are bugs that cause the kernel to leave a task stuck
1050	  in uninterruptible "D" state.
1051
1052	  The panic can be used in combination with panic_timeout,
1053	  to cause the system to reboot automatically after a
1054	  hung task has been detected. This feature is useful for
1055	  high-availability systems that have uptime guarantees and
1056	  where a hung tasks must be resolved ASAP.
1057
1058	  Say N if unsure.
1059
1060config BOOTPARAM_HUNG_TASK_PANIC_VALUE
1061	int
1062	depends on DETECT_HUNG_TASK
1063	range 0 1
1064	default 0 if !BOOTPARAM_HUNG_TASK_PANIC
1065	default 1 if BOOTPARAM_HUNG_TASK_PANIC
1066
1067config WQ_WATCHDOG
1068	bool "Detect Workqueue Stalls"
1069	depends on DEBUG_KERNEL
1070	help
1071	  Say Y here to enable stall detection on workqueues.  If a
1072	  worker pool doesn't make forward progress on a pending work
1073	  item for over a given amount of time, 30s by default, a
1074	  warning message is printed along with dump of workqueue
1075	  state.  This can be configured through kernel parameter
1076	  "workqueue.watchdog_thresh" and its sysfs counterpart.
1077
1078config TEST_LOCKUP
1079	tristate "Test module to generate lockups"
1080	depends on m
1081	help
1082	  This builds the "test_lockup" module that helps to make sure
1083	  that watchdogs and lockup detectors are working properly.
1084
1085	  Depending on module parameters it could emulate soft or hard
1086	  lockup, "hung task", or locking arbitrary lock for a long time.
1087	  Also it could generate series of lockups with cooling-down periods.
1088
1089	  If unsure, say N.
1090
1091endmenu # "Debug lockups and hangs"
1092
1093menu "Scheduler Debugging"
1094
1095config SCHED_DEBUG
1096	bool "Collect scheduler debugging info"
1097	depends on DEBUG_KERNEL && PROC_FS
1098	default y
1099	help
1100	  If you say Y here, the /proc/sched_debug file will be provided
1101	  that can help debug the scheduler. The runtime overhead of this
1102	  option is minimal.
1103
1104config SCHED_INFO
1105	bool
1106	default n
1107
1108config SCHEDSTATS
1109	bool "Collect scheduler statistics"
1110	depends on DEBUG_KERNEL && PROC_FS
1111	select SCHED_INFO
1112	help
1113	  If you say Y here, additional code will be inserted into the
1114	  scheduler and related routines to collect statistics about
1115	  scheduler behavior and provide them in /proc/schedstat.  These
1116	  stats may be useful for both tuning and debugging the scheduler
1117	  If you aren't debugging the scheduler or trying to tune a specific
1118	  application, you can say N to avoid the very slight overhead
1119	  this adds.
1120
1121endmenu
1122
1123config DEBUG_TIMEKEEPING
1124	bool "Enable extra timekeeping sanity checking"
1125	help
1126	  This option will enable additional timekeeping sanity checks
1127	  which may be helpful when diagnosing issues where timekeeping
1128	  problems are suspected.
1129
1130	  This may include checks in the timekeeping hotpaths, so this
1131	  option may have a (very small) performance impact to some
1132	  workloads.
1133
1134	  If unsure, say N.
1135
1136config DEBUG_PREEMPT
1137	bool "Debug preemptible kernel"
1138	depends on DEBUG_KERNEL && PREEMPTION && TRACE_IRQFLAGS_SUPPORT
1139	default y
1140	help
1141	  If you say Y here then the kernel will use a debug variant of the
1142	  commonly used smp_processor_id() function and will print warnings
1143	  if kernel code uses it in a preemption-unsafe way. Also, the kernel
1144	  will detect preemption count underflows.
1145
1146menu "Lock Debugging (spinlocks, mutexes, etc...)"
1147
1148config LOCK_DEBUGGING_SUPPORT
1149	bool
1150	depends on TRACE_IRQFLAGS_SUPPORT && STACKTRACE_SUPPORT && LOCKDEP_SUPPORT
1151	default y
1152
1153config PROVE_LOCKING
1154	bool "Lock debugging: prove locking correctness"
1155	depends on DEBUG_KERNEL && LOCK_DEBUGGING_SUPPORT
1156	select LOCKDEP
1157	select DEBUG_SPINLOCK
1158	select DEBUG_MUTEXES
1159	select DEBUG_RT_MUTEXES if RT_MUTEXES
1160	select DEBUG_RWSEMS
1161	select DEBUG_WW_MUTEX_SLOWPATH
1162	select DEBUG_LOCK_ALLOC
1163	select PREEMPT_COUNT if !ARCH_NO_PREEMPT
1164	select TRACE_IRQFLAGS
1165	default n
1166	help
1167	 This feature enables the kernel to prove that all locking
1168	 that occurs in the kernel runtime is mathematically
1169	 correct: that under no circumstance could an arbitrary (and
1170	 not yet triggered) combination of observed locking
1171	 sequences (on an arbitrary number of CPUs, running an
1172	 arbitrary number of tasks and interrupt contexts) cause a
1173	 deadlock.
1174
1175	 In short, this feature enables the kernel to report locking
1176	 related deadlocks before they actually occur.
1177
1178	 The proof does not depend on how hard and complex a
1179	 deadlock scenario would be to trigger: how many
1180	 participant CPUs, tasks and irq-contexts would be needed
1181	 for it to trigger. The proof also does not depend on
1182	 timing: if a race and a resulting deadlock is possible
1183	 theoretically (no matter how unlikely the race scenario
1184	 is), it will be proven so and will immediately be
1185	 reported by the kernel (once the event is observed that
1186	 makes the deadlock theoretically possible).
1187
1188	 If a deadlock is impossible (i.e. the locking rules, as
1189	 observed by the kernel, are mathematically correct), the
1190	 kernel reports nothing.
1191
1192	 NOTE: this feature can also be enabled for rwlocks, mutexes
1193	 and rwsems - in which case all dependencies between these
1194	 different locking variants are observed and mapped too, and
1195	 the proof of observed correctness is also maintained for an
1196	 arbitrary combination of these separate locking variants.
1197
1198	 For more details, see Documentation/locking/lockdep-design.rst.
1199
1200config PROVE_RAW_LOCK_NESTING
1201	bool "Enable raw_spinlock - spinlock nesting checks"
1202	depends on PROVE_LOCKING
1203	default n
1204	help
1205	 Enable the raw_spinlock vs. spinlock nesting checks which ensure
1206	 that the lock nesting rules for PREEMPT_RT enabled kernels are
1207	 not violated.
1208
1209	 NOTE: There are known nesting problems. So if you enable this
1210	 option expect lockdep splats until these problems have been fully
1211	 addressed which is work in progress. This config switch allows to
1212	 identify and analyze these problems. It will be removed and the
1213	 check permanentely enabled once the main issues have been fixed.
1214
1215	 If unsure, select N.
1216
1217config LOCK_STAT
1218	bool "Lock usage statistics"
1219	depends on DEBUG_KERNEL && LOCK_DEBUGGING_SUPPORT
1220	select LOCKDEP
1221	select DEBUG_SPINLOCK
1222	select DEBUG_MUTEXES
1223	select DEBUG_RT_MUTEXES if RT_MUTEXES
1224	select DEBUG_LOCK_ALLOC
1225	default n
1226	help
1227	 This feature enables tracking lock contention points
1228
1229	 For more details, see Documentation/locking/lockstat.rst
1230
1231	 This also enables lock events required by "perf lock",
1232	 subcommand of perf.
1233	 If you want to use "perf lock", you also need to turn on
1234	 CONFIG_EVENT_TRACING.
1235
1236	 CONFIG_LOCK_STAT defines "contended" and "acquired" lock events.
1237	 (CONFIG_LOCKDEP defines "acquire" and "release" events.)
1238
1239config DEBUG_RT_MUTEXES
1240	bool "RT Mutex debugging, deadlock detection"
1241	depends on DEBUG_KERNEL && RT_MUTEXES
1242	help
1243	 This allows rt mutex semantics violations and rt mutex related
1244	 deadlocks (lockups) to be detected and reported automatically.
1245
1246config DEBUG_SPINLOCK
1247	bool "Spinlock and rw-lock debugging: basic checks"
1248	depends on DEBUG_KERNEL
1249	select UNINLINE_SPIN_UNLOCK
1250	help
1251	  Say Y here and build SMP to catch missing spinlock initialization
1252	  and certain other kinds of spinlock errors commonly made.  This is
1253	  best used in conjunction with the NMI watchdog so that spinlock
1254	  deadlocks are also debuggable.
1255
1256config DEBUG_MUTEXES
1257	bool "Mutex debugging: basic checks"
1258	depends on DEBUG_KERNEL
1259	help
1260	 This feature allows mutex semantics violations to be detected and
1261	 reported.
1262
1263config DEBUG_WW_MUTEX_SLOWPATH
1264	bool "Wait/wound mutex debugging: Slowpath testing"
1265	depends on DEBUG_KERNEL && LOCK_DEBUGGING_SUPPORT
1266	select DEBUG_LOCK_ALLOC
1267	select DEBUG_SPINLOCK
1268	select DEBUG_MUTEXES
1269	help
1270	 This feature enables slowpath testing for w/w mutex users by
1271	 injecting additional -EDEADLK wound/backoff cases. Together with
1272	 the full mutex checks enabled with (CONFIG_PROVE_LOCKING) this
1273	 will test all possible w/w mutex interface abuse with the
1274	 exception of simply not acquiring all the required locks.
1275	 Note that this feature can introduce significant overhead, so
1276	 it really should not be enabled in a production or distro kernel,
1277	 even a debug kernel.  If you are a driver writer, enable it.  If
1278	 you are a distro, do not.
1279
1280config DEBUG_RWSEMS
1281	bool "RW Semaphore debugging: basic checks"
1282	depends on DEBUG_KERNEL
1283	help
1284	  This debugging feature allows mismatched rw semaphore locks
1285	  and unlocks to be detected and reported.
1286
1287config DEBUG_LOCK_ALLOC
1288	bool "Lock debugging: detect incorrect freeing of live locks"
1289	depends on DEBUG_KERNEL && LOCK_DEBUGGING_SUPPORT
1290	select DEBUG_SPINLOCK
1291	select DEBUG_MUTEXES
1292	select DEBUG_RT_MUTEXES if RT_MUTEXES
1293	select LOCKDEP
1294	help
1295	 This feature will check whether any held lock (spinlock, rwlock,
1296	 mutex or rwsem) is incorrectly freed by the kernel, via any of the
1297	 memory-freeing routines (kfree(), kmem_cache_free(), free_pages(),
1298	 vfree(), etc.), whether a live lock is incorrectly reinitialized via
1299	 spin_lock_init()/mutex_init()/etc., or whether there is any lock
1300	 held during task exit.
1301
1302config LOCKDEP
1303	bool
1304	depends on DEBUG_KERNEL && LOCK_DEBUGGING_SUPPORT
1305	select STACKTRACE
1306	select KALLSYMS
1307	select KALLSYMS_ALL
1308
1309config LOCKDEP_SMALL
1310	bool
1311
1312config LOCKDEP_BITS
1313	int "Bitsize for MAX_LOCKDEP_ENTRIES"
1314	depends on LOCKDEP && !LOCKDEP_SMALL
1315	range 10 30
1316	default 15
1317	help
1318	  Try increasing this value if you hit "BUG: MAX_LOCKDEP_ENTRIES too low!" message.
1319
1320config LOCKDEP_CHAINS_BITS
1321	int "Bitsize for MAX_LOCKDEP_CHAINS"
1322	depends on LOCKDEP && !LOCKDEP_SMALL
1323	range 10 30
1324	default 16
1325	help
1326	  Try increasing this value if you hit "BUG: MAX_LOCKDEP_CHAINS too low!" message.
1327
1328config LOCKDEP_STACK_TRACE_BITS
1329	int "Bitsize for MAX_STACK_TRACE_ENTRIES"
1330	depends on LOCKDEP && !LOCKDEP_SMALL
1331	range 10 30
1332	default 19
1333	help
1334	  Try increasing this value if you hit "BUG: MAX_STACK_TRACE_ENTRIES too low!" message.
1335
1336config LOCKDEP_STACK_TRACE_HASH_BITS
1337	int "Bitsize for STACK_TRACE_HASH_SIZE"
1338	depends on LOCKDEP && !LOCKDEP_SMALL
1339	range 10 30
1340	default 14
1341	help
1342	  Try increasing this value if you need large MAX_STACK_TRACE_ENTRIES.
1343
1344config LOCKDEP_CIRCULAR_QUEUE_BITS
1345	int "Bitsize for elements in circular_queue struct"
1346	depends on LOCKDEP
1347	range 10 30
1348	default 12
1349	help
1350	  Try increasing this value if you hit "lockdep bfs error:-1" warning due to __cq_enqueue() failure.
1351
1352config DEBUG_LOCKDEP
1353	bool "Lock dependency engine debugging"
1354	depends on DEBUG_KERNEL && LOCKDEP
1355	help
1356	  If you say Y here, the lock dependency engine will do
1357	  additional runtime checks to debug itself, at the price
1358	  of more runtime overhead.
1359
1360config DEBUG_ATOMIC_SLEEP
1361	bool "Sleep inside atomic section checking"
1362	select PREEMPT_COUNT
1363	depends on DEBUG_KERNEL
1364	depends on !ARCH_NO_PREEMPT
1365	help
1366	  If you say Y here, various routines which may sleep will become very
1367	  noisy if they are called inside atomic sections: when a spinlock is
1368	  held, inside an rcu read side critical section, inside preempt disabled
1369	  sections, inside an interrupt, etc...
1370
1371config DEBUG_LOCKING_API_SELFTESTS
1372	bool "Locking API boot-time self-tests"
1373	depends on DEBUG_KERNEL
1374	help
1375	  Say Y here if you want the kernel to run a short self-test during
1376	  bootup. The self-test checks whether common types of locking bugs
1377	  are detected by debugging mechanisms or not. (if you disable
1378	  lock debugging then those bugs wont be detected of course.)
1379	  The following locking APIs are covered: spinlocks, rwlocks,
1380	  mutexes and rwsems.
1381
1382config LOCK_TORTURE_TEST
1383	tristate "torture tests for locking"
1384	depends on DEBUG_KERNEL
1385	select TORTURE_TEST
1386	help
1387	  This option provides a kernel module that runs torture tests
1388	  on kernel locking primitives.  The kernel module may be built
1389	  after the fact on the running kernel to be tested, if desired.
1390
1391	  Say Y here if you want kernel locking-primitive torture tests
1392	  to be built into the kernel.
1393	  Say M if you want these torture tests to build as a module.
1394	  Say N if you are unsure.
1395
1396config WW_MUTEX_SELFTEST
1397	tristate "Wait/wound mutex selftests"
1398	help
1399	  This option provides a kernel module that runs tests on the
1400	  on the struct ww_mutex locking API.
1401
1402	  It is recommended to enable DEBUG_WW_MUTEX_SLOWPATH in conjunction
1403	  with this test harness.
1404
1405	  Say M if you want these self tests to build as a module.
1406	  Say N if you are unsure.
1407
1408config SCF_TORTURE_TEST
1409	tristate "torture tests for smp_call_function*()"
1410	depends on DEBUG_KERNEL
1411	select TORTURE_TEST
1412	help
1413	  This option provides a kernel module that runs torture tests
1414	  on the smp_call_function() family of primitives.  The kernel
1415	  module may be built after the fact on the running kernel to
1416	  be tested, if desired.
1417
1418config CSD_LOCK_WAIT_DEBUG
1419	bool "Debugging for csd_lock_wait(), called from smp_call_function*()"
1420	depends on DEBUG_KERNEL
1421	depends on 64BIT
1422	default n
1423	help
1424	  This option enables debug prints when CPUs are slow to respond
1425	  to the smp_call_function*() IPI wrappers.  These debug prints
1426	  include the IPI handler function currently executing (if any)
1427	  and relevant stack traces.
1428
1429endmenu # lock debugging
1430
1431config TRACE_IRQFLAGS
1432	depends on TRACE_IRQFLAGS_SUPPORT
1433	bool
1434	help
1435	  Enables hooks to interrupt enabling and disabling for
1436	  either tracing or lock debugging.
1437
1438config TRACE_IRQFLAGS_NMI
1439	def_bool y
1440	depends on TRACE_IRQFLAGS
1441	depends on TRACE_IRQFLAGS_NMI_SUPPORT
1442
1443config STACKTRACE
1444	bool "Stack backtrace support"
1445	depends on STACKTRACE_SUPPORT
1446	help
1447	  This option causes the kernel to create a /proc/pid/stack for
1448	  every process, showing its current stack trace.
1449	  It is also used by various kernel debugging features that require
1450	  stack trace generation.
1451
1452config WARN_ALL_UNSEEDED_RANDOM
1453	bool "Warn for all uses of unseeded randomness"
1454	default n
1455	help
1456	  Some parts of the kernel contain bugs relating to their use of
1457	  cryptographically secure random numbers before it's actually possible
1458	  to generate those numbers securely. This setting ensures that these
1459	  flaws don't go unnoticed, by enabling a message, should this ever
1460	  occur. This will allow people with obscure setups to know when things
1461	  are going wrong, so that they might contact developers about fixing
1462	  it.
1463
1464	  Unfortunately, on some models of some architectures getting
1465	  a fully seeded CRNG is extremely difficult, and so this can
1466	  result in dmesg getting spammed for a surprisingly long
1467	  time.  This is really bad from a security perspective, and
1468	  so architecture maintainers really need to do what they can
1469	  to get the CRNG seeded sooner after the system is booted.
1470	  However, since users cannot do anything actionable to
1471	  address this, by default this option is disabled.
1472
1473	  Say Y here if you want to receive warnings for all uses of
1474	  unseeded randomness.  This will be of use primarily for
1475	  those developers interested in improving the security of
1476	  Linux kernels running on their architecture (or
1477	  subarchitecture).
1478
1479config DEBUG_KOBJECT
1480	bool "kobject debugging"
1481	depends on DEBUG_KERNEL
1482	help
1483	  If you say Y here, some extra kobject debugging messages will be sent
1484	  to the syslog.
1485
1486config DEBUG_KOBJECT_RELEASE
1487	bool "kobject release debugging"
1488	depends on DEBUG_OBJECTS_TIMERS
1489	help
1490	  kobjects are reference counted objects.  This means that their
1491	  last reference count put is not predictable, and the kobject can
1492	  live on past the point at which a driver decides to drop it's
1493	  initial reference to the kobject gained on allocation.  An
1494	  example of this would be a struct device which has just been
1495	  unregistered.
1496
1497	  However, some buggy drivers assume that after such an operation,
1498	  the memory backing the kobject can be immediately freed.  This
1499	  goes completely against the principles of a refcounted object.
1500
1501	  If you say Y here, the kernel will delay the release of kobjects
1502	  on the last reference count to improve the visibility of this
1503	  kind of kobject release bug.
1504
1505config HAVE_DEBUG_BUGVERBOSE
1506	bool
1507
1508menu "Debug kernel data structures"
1509
1510config DEBUG_LIST
1511	bool "Debug linked list manipulation"
1512	depends on DEBUG_KERNEL || BUG_ON_DATA_CORRUPTION
1513	help
1514	  Enable this to turn on extended checks in the linked-list
1515	  walking routines.
1516
1517	  If unsure, say N.
1518
1519config DEBUG_PLIST
1520	bool "Debug priority linked list manipulation"
1521	depends on DEBUG_KERNEL
1522	help
1523	  Enable this to turn on extended checks in the priority-ordered
1524	  linked-list (plist) walking routines.  This checks the entire
1525	  list multiple times during each manipulation.
1526
1527	  If unsure, say N.
1528
1529config DEBUG_SG
1530	bool "Debug SG table operations"
1531	depends on DEBUG_KERNEL
1532	help
1533	  Enable this to turn on checks on scatter-gather tables. This can
1534	  help find problems with drivers that do not properly initialize
1535	  their sg tables.
1536
1537	  If unsure, say N.
1538
1539config DEBUG_NOTIFIERS
1540	bool "Debug notifier call chains"
1541	depends on DEBUG_KERNEL
1542	help
1543	  Enable this to turn on sanity checking for notifier call chains.
1544	  This is most useful for kernel developers to make sure that
1545	  modules properly unregister themselves from notifier chains.
1546	  This is a relatively cheap check but if you care about maximum
1547	  performance, say N.
1548
1549config BUG_ON_DATA_CORRUPTION
1550	bool "Trigger a BUG when data corruption is detected"
1551	select DEBUG_LIST
1552	help
1553	  Select this option if the kernel should BUG when it encounters
1554	  data corruption in kernel memory structures when they get checked
1555	  for validity.
1556
1557	  If unsure, say N.
1558
1559endmenu
1560
1561config DEBUG_CREDENTIALS
1562	bool "Debug credential management"
1563	depends on DEBUG_KERNEL
1564	help
1565	  Enable this to turn on some debug checking for credential
1566	  management.  The additional code keeps track of the number of
1567	  pointers from task_structs to any given cred struct, and checks to
1568	  see that this number never exceeds the usage count of the cred
1569	  struct.
1570
1571	  Furthermore, if SELinux is enabled, this also checks that the
1572	  security pointer in the cred struct is never seen to be invalid.
1573
1574	  If unsure, say N.
1575
1576source "kernel/rcu/Kconfig.debug"
1577
1578config DEBUG_WQ_FORCE_RR_CPU
1579	bool "Force round-robin CPU selection for unbound work items"
1580	depends on DEBUG_KERNEL
1581	default n
1582	help
1583	  Workqueue used to implicitly guarantee that work items queued
1584	  without explicit CPU specified are put on the local CPU.  This
1585	  guarantee is no longer true and while local CPU is still
1586	  preferred work items may be put on foreign CPUs.  Kernel
1587	  parameter "workqueue.debug_force_rr_cpu" is added to force
1588	  round-robin CPU selection to flush out usages which depend on the
1589	  now broken guarantee.  This config option enables the debug
1590	  feature by default.  When enabled, memory and cache locality will
1591	  be impacted.
1592
1593config DEBUG_BLOCK_EXT_DEVT
1594	bool "Force extended block device numbers and spread them"
1595	depends on DEBUG_KERNEL
1596	depends on BLOCK
1597	default n
1598	help
1599	  BIG FAT WARNING: ENABLING THIS OPTION MIGHT BREAK BOOTING ON
1600	  SOME DISTRIBUTIONS.  DO NOT ENABLE THIS UNLESS YOU KNOW WHAT
1601	  YOU ARE DOING.  Distros, please enable this and fix whatever
1602	  is broken.
1603
1604	  Conventionally, block device numbers are allocated from
1605	  predetermined contiguous area.  However, extended block area
1606	  may introduce non-contiguous block device numbers.  This
1607	  option forces most block device numbers to be allocated from
1608	  the extended space and spreads them to discover kernel or
1609	  userland code paths which assume predetermined contiguous
1610	  device number allocation.
1611
1612	  Note that turning on this debug option shuffles all the
1613	  device numbers for all IDE and SCSI devices including libata
1614	  ones, so root partition specified using device number
1615	  directly (via rdev or root=MAJ:MIN) won't work anymore.
1616	  Textual device names (root=/dev/sdXn) will continue to work.
1617
1618	  Say N if you are unsure.
1619
1620config CPU_HOTPLUG_STATE_CONTROL
1621	bool "Enable CPU hotplug state control"
1622	depends on DEBUG_KERNEL
1623	depends on HOTPLUG_CPU
1624	default n
1625	help
1626	  Allows to write steps between "offline" and "online" to the CPUs
1627	  sysfs target file so states can be stepped granular. This is a debug
1628	  option for now as the hotplug machinery cannot be stopped and
1629	  restarted at arbitrary points yet.
1630
1631	  Say N if your are unsure.
1632
1633config LATENCYTOP
1634	bool "Latency measuring infrastructure"
1635	depends on DEBUG_KERNEL
1636	depends on STACKTRACE_SUPPORT
1637	depends on PROC_FS
1638	depends on FRAME_POINTER || MIPS || PPC || S390 || MICROBLAZE || ARM || ARC || X86
1639	select KALLSYMS
1640	select KALLSYMS_ALL
1641	select STACKTRACE
1642	select SCHEDSTATS
1643	select SCHED_DEBUG
1644	help
1645	  Enable this option if you want to use the LatencyTOP tool
1646	  to find out which userspace is blocking on what kernel operations.
1647
1648source "kernel/trace/Kconfig"
1649
1650config PROVIDE_OHCI1394_DMA_INIT
1651	bool "Remote debugging over FireWire early on boot"
1652	depends on PCI && X86
1653	help
1654	  If you want to debug problems which hang or crash the kernel early
1655	  on boot and the crashing machine has a FireWire port, you can use
1656	  this feature to remotely access the memory of the crashed machine
1657	  over FireWire. This employs remote DMA as part of the OHCI1394
1658	  specification which is now the standard for FireWire controllers.
1659
1660	  With remote DMA, you can monitor the printk buffer remotely using
1661	  firescope and access all memory below 4GB using fireproxy from gdb.
1662	  Even controlling a kernel debugger is possible using remote DMA.
1663
1664	  Usage:
1665
1666	  If ohci1394_dma=early is used as boot parameter, it will initialize
1667	  all OHCI1394 controllers which are found in the PCI config space.
1668
1669	  As all changes to the FireWire bus such as enabling and disabling
1670	  devices cause a bus reset and thereby disable remote DMA for all
1671	  devices, be sure to have the cable plugged and FireWire enabled on
1672	  the debugging host before booting the debug target for debugging.
1673
1674	  This code (~1k) is freed after boot. By then, the firewire stack
1675	  in charge of the OHCI-1394 controllers should be used instead.
1676
1677	  See Documentation/core-api/debugging-via-ohci1394.rst for more information.
1678
1679source "samples/Kconfig"
1680
1681config ARCH_HAS_DEVMEM_IS_ALLOWED
1682	bool
1683
1684config STRICT_DEVMEM
1685	bool "Filter access to /dev/mem"
1686	depends on MMU && DEVMEM
1687	depends on ARCH_HAS_DEVMEM_IS_ALLOWED
1688	default y if PPC || X86 || ARM64
1689	help
1690	  If this option is disabled, you allow userspace (root) access to all
1691	  of memory, including kernel and userspace memory. Accidental
1692	  access to this is obviously disastrous, but specific access can
1693	  be used by people debugging the kernel. Note that with PAT support
1694	  enabled, even in this case there are restrictions on /dev/mem
1695	  use due to the cache aliasing requirements.
1696
1697	  If this option is switched on, and IO_STRICT_DEVMEM=n, the /dev/mem
1698	  file only allows userspace access to PCI space and the BIOS code and
1699	  data regions.  This is sufficient for dosemu and X and all common
1700	  users of /dev/mem.
1701
1702	  If in doubt, say Y.
1703
1704config IO_STRICT_DEVMEM
1705	bool "Filter I/O access to /dev/mem"
1706	depends on STRICT_DEVMEM
1707	help
1708	  If this option is disabled, you allow userspace (root) access to all
1709	  io-memory regardless of whether a driver is actively using that
1710	  range.  Accidental access to this is obviously disastrous, but
1711	  specific access can be used by people debugging kernel drivers.
1712
1713	  If this option is switched on, the /dev/mem file only allows
1714	  userspace access to *idle* io-memory ranges (see /proc/iomem) This
1715	  may break traditional users of /dev/mem (dosemu, legacy X, etc...)
1716	  if the driver using a given range cannot be disabled.
1717
1718	  If in doubt, say Y.
1719
1720menu "$(SRCARCH) Debugging"
1721
1722source "arch/$(SRCARCH)/Kconfig.debug"
1723
1724endmenu
1725
1726menu "Kernel Testing and Coverage"
1727
1728source "lib/kunit/Kconfig"
1729
1730config NOTIFIER_ERROR_INJECTION
1731	tristate "Notifier error injection"
1732	depends on DEBUG_KERNEL
1733	select DEBUG_FS
1734	help
1735	  This option provides the ability to inject artificial errors to
1736	  specified notifier chain callbacks. It is useful to test the error
1737	  handling of notifier call chain failures.
1738
1739	  Say N if unsure.
1740
1741config PM_NOTIFIER_ERROR_INJECT
1742	tristate "PM notifier error injection module"
1743	depends on PM && NOTIFIER_ERROR_INJECTION
1744	default m if PM_DEBUG
1745	help
1746	  This option provides the ability to inject artificial errors to
1747	  PM notifier chain callbacks.  It is controlled through debugfs
1748	  interface /sys/kernel/debug/notifier-error-inject/pm
1749
1750	  If the notifier call chain should be failed with some events
1751	  notified, write the error code to "actions/<notifier event>/error".
1752
1753	  Example: Inject PM suspend error (-12 = -ENOMEM)
1754
1755	  # cd /sys/kernel/debug/notifier-error-inject/pm/
1756	  # echo -12 > actions/PM_SUSPEND_PREPARE/error
1757	  # echo mem > /sys/power/state
1758	  bash: echo: write error: Cannot allocate memory
1759
1760	  To compile this code as a module, choose M here: the module will
1761	  be called pm-notifier-error-inject.
1762
1763	  If unsure, say N.
1764
1765config OF_RECONFIG_NOTIFIER_ERROR_INJECT
1766	tristate "OF reconfig notifier error injection module"
1767	depends on OF_DYNAMIC && NOTIFIER_ERROR_INJECTION
1768	help
1769	  This option provides the ability to inject artificial errors to
1770	  OF reconfig notifier chain callbacks.  It is controlled
1771	  through debugfs interface under
1772	  /sys/kernel/debug/notifier-error-inject/OF-reconfig/
1773
1774	  If the notifier call chain should be failed with some events
1775	  notified, write the error code to "actions/<notifier event>/error".
1776
1777	  To compile this code as a module, choose M here: the module will
1778	  be called of-reconfig-notifier-error-inject.
1779
1780	  If unsure, say N.
1781
1782config NETDEV_NOTIFIER_ERROR_INJECT
1783	tristate "Netdev notifier error injection module"
1784	depends on NET && NOTIFIER_ERROR_INJECTION
1785	help
1786	  This option provides the ability to inject artificial errors to
1787	  netdevice notifier chain callbacks.  It is controlled through debugfs
1788	  interface /sys/kernel/debug/notifier-error-inject/netdev
1789
1790	  If the notifier call chain should be failed with some events
1791	  notified, write the error code to "actions/<notifier event>/error".
1792
1793	  Example: Inject netdevice mtu change error (-22 = -EINVAL)
1794
1795	  # cd /sys/kernel/debug/notifier-error-inject/netdev
1796	  # echo -22 > actions/NETDEV_CHANGEMTU/error
1797	  # ip link set eth0 mtu 1024
1798	  RTNETLINK answers: Invalid argument
1799
1800	  To compile this code as a module, choose M here: the module will
1801	  be called netdev-notifier-error-inject.
1802
1803	  If unsure, say N.
1804
1805config FUNCTION_ERROR_INJECTION
1806	bool "Fault-injections of functions"
1807	depends on HAVE_FUNCTION_ERROR_INJECTION && KPROBES
1808	help
1809	  Add fault injections into various functions that are annotated with
1810	  ALLOW_ERROR_INJECTION() in the kernel. BPF may also modify the return
1811	  value of theses functions. This is useful to test error paths of code.
1812
1813	  If unsure, say N
1814
1815config FAULT_INJECTION
1816	bool "Fault-injection framework"
1817	depends on DEBUG_KERNEL
1818	help
1819	  Provide fault-injection framework.
1820	  For more details, see Documentation/fault-injection/.
1821
1822config FAILSLAB
1823	bool "Fault-injection capability for kmalloc"
1824	depends on FAULT_INJECTION
1825	depends on SLAB || SLUB
1826	help
1827	  Provide fault-injection capability for kmalloc.
1828
1829config FAIL_PAGE_ALLOC
1830	bool "Fault-injection capability for alloc_pages()"
1831	depends on FAULT_INJECTION
1832	help
1833	  Provide fault-injection capability for alloc_pages().
1834
1835config FAULT_INJECTION_USERCOPY
1836	bool "Fault injection capability for usercopy functions"
1837	depends on FAULT_INJECTION
1838	help
1839	  Provides fault-injection capability to inject failures
1840	  in usercopy functions (copy_from_user(), get_user(), ...).
1841
1842config FAIL_MAKE_REQUEST
1843	bool "Fault-injection capability for disk IO"
1844	depends on FAULT_INJECTION && BLOCK
1845	help
1846	  Provide fault-injection capability for disk IO.
1847
1848config FAIL_IO_TIMEOUT
1849	bool "Fault-injection capability for faking disk interrupts"
1850	depends on FAULT_INJECTION && BLOCK
1851	help
1852	  Provide fault-injection capability on end IO handling. This
1853	  will make the block layer "forget" an interrupt as configured,
1854	  thus exercising the error handling.
1855
1856	  Only works with drivers that use the generic timeout handling,
1857	  for others it wont do anything.
1858
1859config FAIL_FUTEX
1860	bool "Fault-injection capability for futexes"
1861	select DEBUG_FS
1862	depends on FAULT_INJECTION && FUTEX
1863	help
1864	  Provide fault-injection capability for futexes.
1865
1866config FAULT_INJECTION_DEBUG_FS
1867	bool "Debugfs entries for fault-injection capabilities"
1868	depends on FAULT_INJECTION && SYSFS && DEBUG_FS
1869	help
1870	  Enable configuration of fault-injection capabilities via debugfs.
1871
1872config FAIL_FUNCTION
1873	bool "Fault-injection capability for functions"
1874	depends on FAULT_INJECTION_DEBUG_FS && FUNCTION_ERROR_INJECTION
1875	help
1876	  Provide function-based fault-injection capability.
1877	  This will allow you to override a specific function with a return
1878	  with given return value. As a result, function caller will see
1879	  an error value and have to handle it. This is useful to test the
1880	  error handling in various subsystems.
1881
1882config FAIL_MMC_REQUEST
1883	bool "Fault-injection capability for MMC IO"
1884	depends on FAULT_INJECTION_DEBUG_FS && MMC
1885	help
1886	  Provide fault-injection capability for MMC IO.
1887	  This will make the mmc core return data errors. This is
1888	  useful to test the error handling in the mmc block device
1889	  and to test how the mmc host driver handles retries from
1890	  the block device.
1891
1892config FAULT_INJECTION_STACKTRACE_FILTER
1893	bool "stacktrace filter for fault-injection capabilities"
1894	depends on FAULT_INJECTION_DEBUG_FS && STACKTRACE_SUPPORT
1895	depends on !X86_64
1896	select STACKTRACE
1897	depends on FRAME_POINTER || MIPS || PPC || S390 || MICROBLAZE || ARM || ARC || X86
1898	help
1899	  Provide stacktrace filter for fault-injection capabilities
1900
1901config ARCH_HAS_KCOV
1902	bool
1903	help
1904	  An architecture should select this when it can successfully
1905	  build and run with CONFIG_KCOV. This typically requires
1906	  disabling instrumentation for some early boot code.
1907
1908config CC_HAS_SANCOV_TRACE_PC
1909	def_bool $(cc-option,-fsanitize-coverage=trace-pc)
1910
1911
1912config KCOV
1913	bool "Code coverage for fuzzing"
1914	depends on ARCH_HAS_KCOV
1915	depends on CC_HAS_SANCOV_TRACE_PC || GCC_PLUGINS
1916	select DEBUG_FS
1917	select GCC_PLUGIN_SANCOV if !CC_HAS_SANCOV_TRACE_PC
1918	help
1919	  KCOV exposes kernel code coverage information in a form suitable
1920	  for coverage-guided fuzzing (randomized testing).
1921
1922	  If RANDOMIZE_BASE is enabled, PC values will not be stable across
1923	  different machines and across reboots. If you need stable PC values,
1924	  disable RANDOMIZE_BASE.
1925
1926	  For more details, see Documentation/dev-tools/kcov.rst.
1927
1928config KCOV_ENABLE_COMPARISONS
1929	bool "Enable comparison operands collection by KCOV"
1930	depends on KCOV
1931	depends on $(cc-option,-fsanitize-coverage=trace-cmp)
1932	help
1933	  KCOV also exposes operands of every comparison in the instrumented
1934	  code along with operand sizes and PCs of the comparison instructions.
1935	  These operands can be used by fuzzing engines to improve the quality
1936	  of fuzzing coverage.
1937
1938config KCOV_INSTRUMENT_ALL
1939	bool "Instrument all code by default"
1940	depends on KCOV
1941	default y
1942	help
1943	  If you are doing generic system call fuzzing (like e.g. syzkaller),
1944	  then you will want to instrument the whole kernel and you should
1945	  say y here. If you are doing more targeted fuzzing (like e.g.
1946	  filesystem fuzzing with AFL) then you will want to enable coverage
1947	  for more specific subsets of files, and should say n here.
1948
1949config KCOV_IRQ_AREA_SIZE
1950	hex "Size of interrupt coverage collection area in words"
1951	depends on KCOV
1952	default 0x40000
1953	help
1954	  KCOV uses preallocated per-cpu areas to collect coverage from
1955	  soft interrupts. This specifies the size of those areas in the
1956	  number of unsigned long words.
1957
1958menuconfig RUNTIME_TESTING_MENU
1959	bool "Runtime Testing"
1960	def_bool y
1961
1962if RUNTIME_TESTING_MENU
1963
1964config LKDTM
1965	tristate "Linux Kernel Dump Test Tool Module"
1966	depends on DEBUG_FS
1967	help
1968	This module enables testing of the different dumping mechanisms by
1969	inducing system failures at predefined crash points.
1970	If you don't need it: say N
1971	Choose M here to compile this code as a module. The module will be
1972	called lkdtm.
1973
1974	Documentation on how to use the module can be found in
1975	Documentation/fault-injection/provoke-crashes.rst
1976
1977config TEST_LIST_SORT
1978	tristate "Linked list sorting test"
1979	depends on DEBUG_KERNEL || m
1980	help
1981	  Enable this to turn on 'list_sort()' function test. This test is
1982	  executed only once during system boot (so affects only boot time),
1983	  or at module load time.
1984
1985	  If unsure, say N.
1986
1987config TEST_MIN_HEAP
1988	tristate "Min heap test"
1989	depends on DEBUG_KERNEL || m
1990	help
1991	  Enable this to turn on min heap function tests. This test is
1992	  executed only once during system boot (so affects only boot time),
1993	  or at module load time.
1994
1995	  If unsure, say N.
1996
1997config TEST_SORT
1998	tristate "Array-based sort test"
1999	depends on DEBUG_KERNEL || m
2000	help
2001	  This option enables the self-test function of 'sort()' at boot,
2002	  or at module load time.
2003
2004	  If unsure, say N.
2005
2006config KPROBES_SANITY_TEST
2007	bool "Kprobes sanity tests"
2008	depends on DEBUG_KERNEL
2009	depends on KPROBES
2010	help
2011	  This option provides for testing basic kprobes functionality on
2012	  boot. Samples of kprobe and kretprobe are inserted and
2013	  verified for functionality.
2014
2015	  Say N if you are unsure.
2016
2017config BACKTRACE_SELF_TEST
2018	tristate "Self test for the backtrace code"
2019	depends on DEBUG_KERNEL
2020	help
2021	  This option provides a kernel module that can be used to test
2022	  the kernel stack backtrace code. This option is not useful
2023	  for distributions or general kernels, but only for kernel
2024	  developers working on architecture code.
2025
2026	  Note that if you want to also test saved backtraces, you will
2027	  have to enable STACKTRACE as well.
2028
2029	  Say N if you are unsure.
2030
2031config RBTREE_TEST
2032	tristate "Red-Black tree test"
2033	depends on DEBUG_KERNEL
2034	help
2035	  A benchmark measuring the performance of the rbtree library.
2036	  Also includes rbtree invariant checks.
2037
2038config REED_SOLOMON_TEST
2039	tristate "Reed-Solomon library test"
2040	depends on DEBUG_KERNEL || m
2041	select REED_SOLOMON
2042	select REED_SOLOMON_ENC16
2043	select REED_SOLOMON_DEC16
2044	help
2045	  This option enables the self-test function of rslib at boot,
2046	  or at module load time.
2047
2048	  If unsure, say N.
2049
2050config INTERVAL_TREE_TEST
2051	tristate "Interval tree test"
2052	depends on DEBUG_KERNEL
2053	select INTERVAL_TREE
2054	help
2055	  A benchmark measuring the performance of the interval tree library
2056
2057config PERCPU_TEST
2058	tristate "Per cpu operations test"
2059	depends on m && DEBUG_KERNEL
2060	help
2061	  Enable this option to build test module which validates per-cpu
2062	  operations.
2063
2064	  If unsure, say N.
2065
2066config ATOMIC64_SELFTEST
2067	tristate "Perform an atomic64_t self-test"
2068	help
2069	  Enable this option to test the atomic64_t functions at boot or
2070	  at module load time.
2071
2072	  If unsure, say N.
2073
2074config ASYNC_RAID6_TEST
2075	tristate "Self test for hardware accelerated raid6 recovery"
2076	depends on ASYNC_RAID6_RECOV
2077	select ASYNC_MEMCPY
2078	help
2079	  This is a one-shot self test that permutes through the
2080	  recovery of all the possible two disk failure scenarios for a
2081	  N-disk array.  Recovery is performed with the asynchronous
2082	  raid6 recovery routines, and will optionally use an offload
2083	  engine if one is available.
2084
2085	  If unsure, say N.
2086
2087config TEST_HEXDUMP
2088	tristate "Test functions located in the hexdump module at runtime"
2089
2090config TEST_STRING_HELPERS
2091	tristate "Test functions located in the string_helpers module at runtime"
2092
2093config TEST_STRSCPY
2094	tristate "Test strscpy*() family of functions at runtime"
2095
2096config TEST_KSTRTOX
2097	tristate "Test kstrto*() family of functions at runtime"
2098
2099config TEST_PRINTF
2100	tristate "Test printf() family of functions at runtime"
2101
2102config TEST_BITMAP
2103	tristate "Test bitmap_*() family of functions at runtime"
2104	help
2105	  Enable this option to test the bitmap functions at boot.
2106
2107	  If unsure, say N.
2108
2109config TEST_UUID
2110	tristate "Test functions located in the uuid module at runtime"
2111
2112config TEST_XARRAY
2113	tristate "Test the XArray code at runtime"
2114
2115config TEST_OVERFLOW
2116	tristate "Test check_*_overflow() functions at runtime"
2117
2118config TEST_RHASHTABLE
2119	tristate "Perform selftest on resizable hash table"
2120	help
2121	  Enable this option to test the rhashtable functions at boot.
2122
2123	  If unsure, say N.
2124
2125config TEST_HASH
2126	tristate "Perform selftest on hash functions"
2127	help
2128	  Enable this option to test the kernel's integer (<linux/hash.h>),
2129	  string (<linux/stringhash.h>), and siphash (<linux/siphash.h>)
2130	  hash functions on boot (or module load).
2131
2132	  This is intended to help people writing architecture-specific
2133	  optimized versions.  If unsure, say N.
2134
2135config TEST_IDA
2136	tristate "Perform selftest on IDA functions"
2137
2138config TEST_PARMAN
2139	tristate "Perform selftest on priority array manager"
2140	depends on PARMAN
2141	help
2142	  Enable this option to test priority array manager on boot
2143	  (or module load).
2144
2145	  If unsure, say N.
2146
2147config TEST_IRQ_TIMINGS
2148	bool "IRQ timings selftest"
2149	depends on IRQ_TIMINGS
2150	help
2151	  Enable this option to test the irq timings code on boot.
2152
2153	  If unsure, say N.
2154
2155config TEST_LKM
2156	tristate "Test module loading with 'hello world' module"
2157	depends on m
2158	help
2159	  This builds the "test_module" module that emits "Hello, world"
2160	  on printk when loaded. It is designed to be used for basic
2161	  evaluation of the module loading subsystem (for example when
2162	  validating module verification). It lacks any extra dependencies,
2163	  and will not normally be loaded by the system unless explicitly
2164	  requested by name.
2165
2166	  If unsure, say N.
2167
2168config TEST_BITOPS
2169	tristate "Test module for compilation of bitops operations"
2170	depends on m
2171	help
2172	  This builds the "test_bitops" module that is much like the
2173	  TEST_LKM module except that it does a basic exercise of the
2174	  set/clear_bit macros and get_count_order/long to make sure there are
2175	  no compiler warnings from C=1 sparse checker or -Wextra
2176	  compilations. It has no dependencies and doesn't run or load unless
2177	  explicitly requested by name.  for example: modprobe test_bitops.
2178
2179	  If unsure, say N.
2180
2181config TEST_VMALLOC
2182	tristate "Test module for stress/performance analysis of vmalloc allocator"
2183	default n
2184       depends on MMU
2185	depends on m
2186	help
2187	  This builds the "test_vmalloc" module that should be used for
2188	  stress and performance analysis. So, any new change for vmalloc
2189	  subsystem can be evaluated from performance and stability point
2190	  of view.
2191
2192	  If unsure, say N.
2193
2194config TEST_USER_COPY
2195	tristate "Test user/kernel boundary protections"
2196	depends on m
2197	help
2198	  This builds the "test_user_copy" module that runs sanity checks
2199	  on the copy_to/from_user infrastructure, making sure basic
2200	  user/kernel boundary testing is working. If it fails to load,
2201	  a regression has been detected in the user/kernel memory boundary
2202	  protections.
2203
2204	  If unsure, say N.
2205
2206config TEST_BPF
2207	tristate "Test BPF filter functionality"
2208	depends on m && NET
2209	help
2210	  This builds the "test_bpf" module that runs various test vectors
2211	  against the BPF interpreter or BPF JIT compiler depending on the
2212	  current setting. This is in particular useful for BPF JIT compiler
2213	  development, but also to run regression tests against changes in
2214	  the interpreter code. It also enables test stubs for eBPF maps and
2215	  verifier used by user space verifier testsuite.
2216
2217	  If unsure, say N.
2218
2219config TEST_BLACKHOLE_DEV
2220	tristate "Test blackhole netdev functionality"
2221	depends on m && NET
2222	help
2223	  This builds the "test_blackhole_dev" module that validates the
2224	  data path through this blackhole netdev.
2225
2226	  If unsure, say N.
2227
2228config FIND_BIT_BENCHMARK
2229	tristate "Test find_bit functions"
2230	help
2231	  This builds the "test_find_bit" module that measure find_*_bit()
2232	  functions performance.
2233
2234	  If unsure, say N.
2235
2236config TEST_FIRMWARE
2237	tristate "Test firmware loading via userspace interface"
2238	depends on FW_LOADER
2239	help
2240	  This builds the "test_firmware" module that creates a userspace
2241	  interface for testing firmware loading. This can be used to
2242	  control the triggering of firmware loading without needing an
2243	  actual firmware-using device. The contents can be rechecked by
2244	  userspace.
2245
2246	  If unsure, say N.
2247
2248config TEST_SYSCTL
2249	tristate "sysctl test driver"
2250	depends on PROC_SYSCTL
2251	help
2252	  This builds the "test_sysctl" module. This driver enables to test the
2253	  proc sysctl interfaces available to drivers safely without affecting
2254	  production knobs which might alter system functionality.
2255
2256	  If unsure, say N.
2257
2258config BITFIELD_KUNIT
2259	tristate "KUnit test bitfield functions at runtime"
2260	depends on KUNIT
2261	help
2262	  Enable this option to test the bitfield functions at boot.
2263
2264	  KUnit tests run during boot and output the results to the debug log
2265	  in TAP format (http://testanything.org/). Only useful for kernel devs
2266	  running the KUnit test harness, and not intended for inclusion into a
2267	  production build.
2268
2269	  For more information on KUnit and unit tests in general please refer
2270	  to the KUnit documentation in Documentation/dev-tools/kunit/.
2271
2272	  If unsure, say N.
2273
2274config SYSCTL_KUNIT_TEST
2275	tristate "KUnit test for sysctl" if !KUNIT_ALL_TESTS
2276	depends on KUNIT
2277	default KUNIT_ALL_TESTS
2278	help
2279	  This builds the proc sysctl unit test, which runs on boot.
2280	  Tests the API contract and implementation correctness of sysctl.
2281	  For more information on KUnit and unit tests in general please refer
2282	  to the KUnit documentation in Documentation/dev-tools/kunit/.
2283
2284	  If unsure, say N.
2285
2286config LIST_KUNIT_TEST
2287	tristate "KUnit Test for Kernel Linked-list structures" if !KUNIT_ALL_TESTS
2288	depends on KUNIT
2289	default KUNIT_ALL_TESTS
2290	help
2291	  This builds the linked list KUnit test suite.
2292	  It tests that the API and basic functionality of the list_head type
2293	  and associated macros.
2294
2295	  KUnit tests run during boot and output the results to the debug log
2296	  in TAP format (https://testanything.org/). Only useful for kernel devs
2297	  running the KUnit test harness, and not intended for inclusion into a
2298	  production build.
2299
2300	  For more information on KUnit and unit tests in general please refer
2301	  to the KUnit documentation in Documentation/dev-tools/kunit/.
2302
2303	  If unsure, say N.
2304
2305config LINEAR_RANGES_TEST
2306	tristate "KUnit test for linear_ranges"
2307	depends on KUNIT
2308	select LINEAR_RANGES
2309	help
2310	  This builds the linear_ranges unit test, which runs on boot.
2311	  Tests the linear_ranges logic correctness.
2312	  For more information on KUnit and unit tests in general please refer
2313	  to the KUnit documentation in Documentation/dev-tools/kunit/.
2314
2315	  If unsure, say N.
2316
2317config BITS_TEST
2318	tristate "KUnit test for bits.h"
2319	depends on KUNIT
2320	help
2321	  This builds the bits unit test.
2322	  Tests the logic of macros defined in bits.h.
2323	  For more information on KUnit and unit tests in general please refer
2324	  to the KUnit documentation in Documentation/dev-tools/kunit/.
2325
2326	  If unsure, say N.
2327
2328config TEST_UDELAY
2329	tristate "udelay test driver"
2330	help
2331	  This builds the "udelay_test" module that helps to make sure
2332	  that udelay() is working properly.
2333
2334	  If unsure, say N.
2335
2336config TEST_STATIC_KEYS
2337	tristate "Test static keys"
2338	depends on m
2339	help
2340	  Test the static key interfaces.
2341
2342	  If unsure, say N.
2343
2344config TEST_KMOD
2345	tristate "kmod stress tester"
2346	depends on m
2347	depends on NETDEVICES && NET_CORE && INET # for TUN
2348	depends on BLOCK
2349	select TEST_LKM
2350	select XFS_FS
2351	select TUN
2352	select BTRFS_FS
2353	help
2354	  Test the kernel's module loading mechanism: kmod. kmod implements
2355	  support to load modules using the Linux kernel's usermode helper.
2356	  This test provides a series of tests against kmod.
2357
2358	  Although technically you can either build test_kmod as a module or
2359	  into the kernel we disallow building it into the kernel since
2360	  it stress tests request_module() and this will very likely cause
2361	  some issues by taking over precious threads available from other
2362	  module load requests, ultimately this could be fatal.
2363
2364	  To run tests run:
2365
2366	  tools/testing/selftests/kmod/kmod.sh --help
2367
2368	  If unsure, say N.
2369
2370config TEST_DEBUG_VIRTUAL
2371	tristate "Test CONFIG_DEBUG_VIRTUAL feature"
2372	depends on DEBUG_VIRTUAL
2373	help
2374	  Test the kernel's ability to detect incorrect calls to
2375	  virt_to_phys() done against the non-linear part of the
2376	  kernel's virtual address map.
2377
2378	  If unsure, say N.
2379
2380config TEST_MEMCAT_P
2381	tristate "Test memcat_p() helper function"
2382	help
2383	  Test the memcat_p() helper for correctly merging two
2384	  pointer arrays together.
2385
2386	  If unsure, say N.
2387
2388config TEST_LIVEPATCH
2389	tristate "Test livepatching"
2390	default n
2391	depends on DYNAMIC_DEBUG
2392	depends on LIVEPATCH
2393	depends on m
2394	help
2395	  Test kernel livepatching features for correctness.  The tests will
2396	  load test modules that will be livepatched in various scenarios.
2397
2398	  To run all the livepatching tests:
2399
2400	  make -C tools/testing/selftests TARGETS=livepatch run_tests
2401
2402	  Alternatively, individual tests may be invoked:
2403
2404	  tools/testing/selftests/livepatch/test-callbacks.sh
2405	  tools/testing/selftests/livepatch/test-livepatch.sh
2406	  tools/testing/selftests/livepatch/test-shadow-vars.sh
2407
2408	  If unsure, say N.
2409
2410config TEST_OBJAGG
2411	tristate "Perform selftest on object aggreration manager"
2412	default n
2413	depends on OBJAGG
2414	help
2415	  Enable this option to test object aggregation manager on boot
2416	  (or module load).
2417
2418
2419config TEST_STACKINIT
2420	tristate "Test level of stack variable initialization"
2421	help
2422	  Test if the kernel is zero-initializing stack variables and
2423	  padding. Coverage is controlled by compiler flags,
2424	  CONFIG_GCC_PLUGIN_STRUCTLEAK, CONFIG_GCC_PLUGIN_STRUCTLEAK_BYREF,
2425	  or CONFIG_GCC_PLUGIN_STRUCTLEAK_BYREF_ALL.
2426
2427	  If unsure, say N.
2428
2429config TEST_MEMINIT
2430	tristate "Test heap/page initialization"
2431	help
2432	  Test if the kernel is zero-initializing heap and page allocations.
2433	  This can be useful to test init_on_alloc and init_on_free features.
2434
2435	  If unsure, say N.
2436
2437config TEST_HMM
2438	tristate "Test HMM (Heterogeneous Memory Management)"
2439	depends on TRANSPARENT_HUGEPAGE
2440	depends on DEVICE_PRIVATE
2441	select HMM_MIRROR
2442	select MMU_NOTIFIER
2443	help
2444	  This is a pseudo device driver solely for testing HMM.
2445	  Say M here if you want to build the HMM test module.
2446	  Doing so will allow you to run tools/testing/selftest/vm/hmm-tests.
2447
2448	  If unsure, say N.
2449
2450config TEST_FREE_PAGES
2451	tristate "Test freeing pages"
2452	help
2453	  Test that a memory leak does not occur due to a race between
2454	  freeing a block of pages and a speculative page reference.
2455	  Loading this module is safe if your kernel has the bug fixed.
2456	  If the bug is not fixed, it will leak gigabytes of memory and
2457	  probably OOM your system.
2458
2459config TEST_FPU
2460	tristate "Test floating point operations in kernel space"
2461	depends on X86 && !KCOV_INSTRUMENT_ALL
2462	help
2463	  Enable this option to add /sys/kernel/debug/selftest_helpers/test_fpu
2464	  which will trigger a sequence of floating point operations. This is used
2465	  for self-testing floating point control register setting in
2466	  kernel_fpu_begin().
2467
2468	  If unsure, say N.
2469
2470endif # RUNTIME_TESTING_MENU
2471
2472config MEMTEST
2473	bool "Memtest"
2474	help
2475	  This option adds a kernel parameter 'memtest', which allows memtest
2476	  to be set.
2477	        memtest=0, mean disabled; -- default
2478	        memtest=1, mean do 1 test pattern;
2479	        ...
2480	        memtest=17, mean do 17 test patterns.
2481	  If you are unsure how to answer this question, answer N.
2482
2483
2484
2485config HYPERV_TESTING
2486	bool "Microsoft Hyper-V driver testing"
2487	default n
2488	depends on HYPERV && DEBUG_FS
2489	help
2490	  Select this option to enable Hyper-V vmbus testing.
2491
2492endmenu # "Kernel Testing and Coverage"
2493
2494source "Documentation/Kconfig"
2495
2496endmenu # Kernel hacking
2497