xref: /openbmc/linux/lib/Kconfig.debug (revision 58277f50)
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
215config DEBUG_INFO_REDUCED
216	bool "Reduce debugging information"
217	depends on DEBUG_INFO
218	help
219	  If you say Y here gcc is instructed to generate less debugging
220	  information for structure types. This means that tools that
221	  need full debugging information (like kgdb or systemtap) won't
222	  be happy. But if you merely need debugging information to
223	  resolve line numbers there is no loss. Advantage is that
224	  build directory object sizes shrink dramatically over a full
225	  DEBUG_INFO build and compile times are reduced too.
226	  Only works with newer gcc versions.
227
228config DEBUG_INFO_COMPRESSED
229	bool "Compressed debugging information"
230	depends on DEBUG_INFO
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 DEBUG_INFO
247	depends on $(cc-option,-gsplit-dwarf)
248	help
249	  Generate debug info into separate .dwo files. This significantly
250	  reduces the build directory size for builds with DEBUG_INFO,
251	  because it stores the information only once on disk in .dwo
252	  files instead of multiple times in object files and executables.
253	  In addition the debug information is also compressed.
254
255	  Requires recent gcc (4.7+) and recent gdb/binutils.
256	  Any tool that packages or reads debug information would need
257	  to know about the .dwo files and include them.
258	  Incompatible with older versions of ccache.
259
260config DEBUG_INFO_DWARF4
261	bool "Generate dwarf4 debuginfo"
262	depends on DEBUG_INFO
263	depends on $(cc-option,-gdwarf-4)
264	help
265	  Generate dwarf4 debug info. This requires recent versions
266	  of gcc and gdb. It makes the debug information larger.
267	  But it significantly improves the success of resolving
268	  variables in gdb on optimized code.
269
270config DEBUG_INFO_BTF
271	bool "Generate BTF typeinfo"
272	depends on DEBUG_INFO
273	depends on !DEBUG_INFO_SPLIT && !DEBUG_INFO_REDUCED
274	depends on !GCC_PLUGIN_RANDSTRUCT || COMPILE_TEST
275	help
276	  Generate deduplicated BTF type information from DWARF debug info.
277	  Turning this on expects presence of pahole tool, which will convert
278	  DWARF type info into equivalent deduplicated BTF type info.
279
280config GDB_SCRIPTS
281	bool "Provide GDB scripts for kernel debugging"
282	depends on DEBUG_INFO
283	help
284	  This creates the required links to GDB helper scripts in the
285	  build directory. If you load vmlinux into gdb, the helper
286	  scripts will be automatically imported by gdb as well, and
287	  additional functions are available to analyze a Linux kernel
288	  instance. See Documentation/dev-tools/gdb-kernel-debugging.rst
289	  for further details.
290
291config ENABLE_MUST_CHECK
292	bool "Enable __must_check logic"
293	default y
294	help
295	  Enable the __must_check logic in the kernel build.  Disable this to
296	  suppress the "warning: ignoring return value of 'foo', declared with
297	  attribute warn_unused_result" messages.
298
299config FRAME_WARN
300	int "Warn for stack frames larger than"
301	range 0 8192
302	default 2048 if GCC_PLUGIN_LATENT_ENTROPY
303	default 1280 if (!64BIT && PARISC)
304	default 1024 if (!64BIT && !PARISC)
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
368#
369# Select this config option from the architecture Kconfig, if it
370# is preferred to always offer frame pointers as a config
371# option on the architecture (regardless of KERNEL_DEBUG):
372#
373config ARCH_WANT_FRAME_POINTERS
374	bool
375
376config FRAME_POINTER
377	bool "Compile the kernel with frame pointers"
378	depends on DEBUG_KERNEL && (M68K || UML || SUPERH) || ARCH_WANT_FRAME_POINTERS
379	default y if (DEBUG_INFO && UML) || ARCH_WANT_FRAME_POINTERS
380	help
381	  If you say Y here the resulting kernel image will be slightly
382	  larger and slower, but it gives very useful debugging information
383	  in case of kernel bugs. (precise oopses/stacktraces/warnings)
384
385config STACK_VALIDATION
386	bool "Compile-time stack metadata validation"
387	depends on HAVE_STACK_VALIDATION
388	default n
389	help
390	  Add compile-time checks to validate stack metadata, including frame
391	  pointers (if CONFIG_FRAME_POINTER is enabled).  This helps ensure
392	  that runtime stack traces are more reliable.
393
394	  This is also a prerequisite for generation of ORC unwind data, which
395	  is needed for CONFIG_UNWINDER_ORC.
396
397	  For more information, see
398	  tools/objtool/Documentation/stack-validation.txt.
399
400config VMLINUX_VALIDATION
401	bool
402	depends on STACK_VALIDATION && DEBUG_ENTRY && !PARAVIRT
403	default y
404
405config DEBUG_FORCE_WEAK_PER_CPU
406	bool "Force weak per-cpu definitions"
407	depends on DEBUG_KERNEL
408	help
409	  s390 and alpha require percpu variables in modules to be
410	  defined weak to work around addressing range issue which
411	  puts the following two restrictions on percpu variable
412	  definitions.
413
414	  1. percpu symbols must be unique whether static or not
415	  2. percpu variables can't be defined inside a function
416
417	  To ensure that generic code follows the above rules, this
418	  option forces all percpu variables to be defined as weak.
419
420endmenu # "Compiler options"
421
422menu "Generic Kernel Debugging Instruments"
423
424config MAGIC_SYSRQ
425	bool "Magic SysRq key"
426	depends on !UML
427	help
428	  If you say Y here, you will have some control over the system even
429	  if the system crashes for example during kernel debugging (e.g., you
430	  will be able to flush the buffer cache to disk, reboot the system
431	  immediately or dump some status information). This is accomplished
432	  by pressing various keys while holding SysRq (Alt+PrintScreen). It
433	  also works on a serial console (on PC hardware at least), if you
434	  send a BREAK and then within 5 seconds a command keypress. The
435	  keys are documented in <file:Documentation/admin-guide/sysrq.rst>.
436	  Don't say Y unless you really know what this hack does.
437
438config MAGIC_SYSRQ_DEFAULT_ENABLE
439	hex "Enable magic SysRq key functions by default"
440	depends on MAGIC_SYSRQ
441	default 0x1
442	help
443	  Specifies which SysRq key functions are enabled by default.
444	  This may be set to 1 or 0 to enable or disable them all, or
445	  to a bitmask as described in Documentation/admin-guide/sysrq.rst.
446
447config MAGIC_SYSRQ_SERIAL
448	bool "Enable magic SysRq key over serial"
449	depends on MAGIC_SYSRQ
450	default y
451	help
452	  Many embedded boards have a disconnected TTL level serial which can
453	  generate some garbage that can lead to spurious false sysrq detects.
454	  This option allows you to decide whether you want to enable the
455	  magic SysRq key.
456
457config MAGIC_SYSRQ_SERIAL_SEQUENCE
458	string "Char sequence that enables magic SysRq over serial"
459	depends on MAGIC_SYSRQ_SERIAL
460	default ""
461	help
462	  Specifies a sequence of characters that can follow BREAK to enable
463	  SysRq on a serial console.
464
465	  If unsure, leave an empty string and the option will not be enabled.
466
467config DEBUG_FS
468	bool "Debug Filesystem"
469	help
470	  debugfs is a virtual file system that kernel developers use to put
471	  debugging files into.  Enable this option to be able to read and
472	  write to these files.
473
474	  For detailed documentation on the debugfs API, see
475	  Documentation/filesystems/.
476
477	  If unsure, say N.
478
479choice
480	prompt "Debugfs default access"
481	depends on DEBUG_FS
482	default DEBUG_FS_ALLOW_ALL
483	help
484	  This selects the default access restrictions for debugfs.
485	  It can be overridden with kernel command line option
486	  debugfs=[on,no-mount,off]. The restrictions apply for API access
487	  and filesystem registration.
488
489config DEBUG_FS_ALLOW_ALL
490	bool "Access normal"
491	help
492	  No restrictions apply. Both API and filesystem registration
493	  is on. This is the normal default operation.
494
495config DEBUG_FS_DISALLOW_MOUNT
496	bool "Do not register debugfs as filesystem"
497	help
498	  The API is open but filesystem is not loaded. Clients can still do
499	  their work and read with debug tools that do not need
500	  debugfs filesystem.
501
502config DEBUG_FS_ALLOW_NONE
503	bool "No access"
504	help
505	  Access is off. Clients get -PERM when trying to create nodes in
506	  debugfs tree and debugfs is not registered as a filesystem.
507	  Client can then back-off or continue without debugfs access.
508
509endchoice
510
511source "lib/Kconfig.kgdb"
512
513source "lib/Kconfig.ubsan"
514
515endmenu
516
517config DEBUG_KERNEL
518	bool "Kernel debugging"
519	help
520	  Say Y here if you are developing drivers or trying to debug and
521	  identify kernel problems.
522
523config DEBUG_MISC
524	bool "Miscellaneous debug code"
525	default DEBUG_KERNEL
526	depends on DEBUG_KERNEL
527	help
528	  Say Y here if you need to enable miscellaneous debug code that should
529	  be under a more specific debug option but isn't.
530
531
532menu "Memory Debugging"
533
534source "mm/Kconfig.debug"
535
536config DEBUG_OBJECTS
537	bool "Debug object operations"
538	depends on DEBUG_KERNEL
539	help
540	  If you say Y here, additional code will be inserted into the
541	  kernel to track the life time of various objects and validate
542	  the operations on those objects.
543
544config DEBUG_OBJECTS_SELFTEST
545	bool "Debug objects selftest"
546	depends on DEBUG_OBJECTS
547	help
548	  This enables the selftest of the object debug code.
549
550config DEBUG_OBJECTS_FREE
551	bool "Debug objects in freed memory"
552	depends on DEBUG_OBJECTS
553	help
554	  This enables checks whether a k/v free operation frees an area
555	  which contains an object which has not been deactivated
556	  properly. This can make kmalloc/kfree-intensive workloads
557	  much slower.
558
559config DEBUG_OBJECTS_TIMERS
560	bool "Debug timer objects"
561	depends on DEBUG_OBJECTS
562	help
563	  If you say Y here, additional code will be inserted into the
564	  timer routines to track the life time of timer objects and
565	  validate the timer operations.
566
567config DEBUG_OBJECTS_WORK
568	bool "Debug work objects"
569	depends on DEBUG_OBJECTS
570	help
571	  If you say Y here, additional code will be inserted into the
572	  work queue routines to track the life time of work objects and
573	  validate the work operations.
574
575config DEBUG_OBJECTS_RCU_HEAD
576	bool "Debug RCU callbacks objects"
577	depends on DEBUG_OBJECTS
578	help
579	  Enable this to turn on debugging of RCU list heads (call_rcu() usage).
580
581config DEBUG_OBJECTS_PERCPU_COUNTER
582	bool "Debug percpu counter objects"
583	depends on DEBUG_OBJECTS
584	help
585	  If you say Y here, additional code will be inserted into the
586	  percpu counter routines to track the life time of percpu counter
587	  objects and validate the percpu counter operations.
588
589config DEBUG_OBJECTS_ENABLE_DEFAULT
590	int "debug_objects bootup default value (0-1)"
591	range 0 1
592	default "1"
593	depends on DEBUG_OBJECTS
594	help
595	  Debug objects boot parameter default value
596
597config DEBUG_SLAB
598	bool "Debug slab memory allocations"
599	depends on DEBUG_KERNEL && SLAB
600	help
601	  Say Y here to have the kernel do limited verification on memory
602	  allocation as well as poisoning memory on free to catch use of freed
603	  memory. This can make kmalloc/kfree-intensive workloads much slower.
604
605config SLUB_DEBUG_ON
606	bool "SLUB debugging on by default"
607	depends on SLUB && SLUB_DEBUG
608	default n
609	help
610	  Boot with debugging on by default. SLUB boots by default with
611	  the runtime debug capabilities switched off. Enabling this is
612	  equivalent to specifying the "slub_debug" parameter on boot.
613	  There is no support for more fine grained debug control like
614	  possible with slub_debug=xxx. SLUB debugging may be switched
615	  off in a kernel built with CONFIG_SLUB_DEBUG_ON by specifying
616	  "slub_debug=-".
617
618config SLUB_STATS
619	default n
620	bool "Enable SLUB performance statistics"
621	depends on SLUB && SYSFS
622	help
623	  SLUB statistics are useful to debug SLUBs allocation behavior in
624	  order find ways to optimize the allocator. This should never be
625	  enabled for production use since keeping statistics slows down
626	  the allocator by a few percentage points. The slabinfo command
627	  supports the determination of the most active slabs to figure
628	  out which slabs are relevant to a particular load.
629	  Try running: slabinfo -DA
630
631config HAVE_DEBUG_KMEMLEAK
632	bool
633
634config DEBUG_KMEMLEAK
635	bool "Kernel memory leak detector"
636	depends on DEBUG_KERNEL && HAVE_DEBUG_KMEMLEAK
637	select DEBUG_FS
638	select STACKTRACE if STACKTRACE_SUPPORT
639	select KALLSYMS
640	select CRC32
641	help
642	  Say Y here if you want to enable the memory leak
643	  detector. The memory allocation/freeing is traced in a way
644	  similar to the Boehm's conservative garbage collector, the
645	  difference being that the orphan objects are not freed but
646	  only shown in /sys/kernel/debug/kmemleak. Enabling this
647	  feature will introduce an overhead to memory
648	  allocations. See Documentation/dev-tools/kmemleak.rst for more
649	  details.
650
651	  Enabling DEBUG_SLAB or SLUB_DEBUG may increase the chances
652	  of finding leaks due to the slab objects poisoning.
653
654	  In order to access the kmemleak file, debugfs needs to be
655	  mounted (usually at /sys/kernel/debug).
656
657config DEBUG_KMEMLEAK_MEM_POOL_SIZE
658	int "Kmemleak memory pool size"
659	depends on DEBUG_KMEMLEAK
660	range 200 1000000
661	default 16000
662	help
663	  Kmemleak must track all the memory allocations to avoid
664	  reporting false positives. Since memory may be allocated or
665	  freed before kmemleak is fully initialised, use a static pool
666	  of metadata objects to track such callbacks. After kmemleak is
667	  fully initialised, this memory pool acts as an emergency one
668	  if slab allocations fail.
669
670config DEBUG_KMEMLEAK_TEST
671	tristate "Simple test for the kernel memory leak detector"
672	depends on DEBUG_KMEMLEAK && m
673	help
674	  This option enables a module that explicitly leaks memory.
675
676	  If unsure, say N.
677
678config DEBUG_KMEMLEAK_DEFAULT_OFF
679	bool "Default kmemleak to off"
680	depends on DEBUG_KMEMLEAK
681	help
682	  Say Y here to disable kmemleak by default. It can then be enabled
683	  on the command line via kmemleak=on.
684
685config DEBUG_KMEMLEAK_AUTO_SCAN
686	bool "Enable kmemleak auto scan thread on boot up"
687	default y
688	depends on DEBUG_KMEMLEAK
689	help
690	  Depending on the cpu, kmemleak scan may be cpu intensive and can
691	  stall user tasks at times. This option enables/disables automatic
692	  kmemleak scan at boot up.
693
694	  Say N here to disable kmemleak auto scan thread to stop automatic
695	  scanning. Disabling this option disables automatic reporting of
696	  memory leaks.
697
698	  If unsure, say Y.
699
700config DEBUG_STACK_USAGE
701	bool "Stack utilization instrumentation"
702	depends on DEBUG_KERNEL && !IA64
703	help
704	  Enables the display of the minimum amount of free stack which each
705	  task has ever had available in the sysrq-T and sysrq-P debug output.
706
707	  This option will slow down process creation somewhat.
708
709config SCHED_STACK_END_CHECK
710	bool "Detect stack corruption on calls to schedule()"
711	depends on DEBUG_KERNEL
712	default n
713	help
714	  This option checks for a stack overrun on calls to schedule().
715	  If the stack end location is found to be over written always panic as
716	  the content of the corrupted region can no longer be trusted.
717	  This is to ensure no erroneous behaviour occurs which could result in
718	  data corruption or a sporadic crash at a later stage once the region
719	  is examined. The runtime overhead introduced is minimal.
720
721config ARCH_HAS_DEBUG_VM_PGTABLE
722	bool
723	help
724	  An architecture should select this when it can successfully
725	  build and run DEBUG_VM_PGTABLE.
726
727config DEBUG_VM
728	bool "Debug VM"
729	depends on DEBUG_KERNEL
730	help
731	  Enable this to turn on extended checks in the virtual-memory system
732	  that may impact performance.
733
734	  If unsure, say N.
735
736config DEBUG_VM_VMACACHE
737	bool "Debug VMA caching"
738	depends on DEBUG_VM
739	help
740	  Enable this to turn on VMA caching debug information. Doing so
741	  can cause significant overhead, so only enable it in non-production
742	  environments.
743
744	  If unsure, say N.
745
746config DEBUG_VM_RB
747	bool "Debug VM red-black trees"
748	depends on DEBUG_VM
749	help
750	  Enable VM red-black tree debugging information and extra validations.
751
752	  If unsure, say N.
753
754config DEBUG_VM_PGFLAGS
755	bool "Debug page-flags operations"
756	depends on DEBUG_VM
757	help
758	  Enables extra validation on page flags operations.
759
760	  If unsure, say N.
761
762config DEBUG_VM_PGTABLE
763	bool "Debug arch page table for semantics compliance"
764	depends on MMU
765	depends on ARCH_HAS_DEBUG_VM_PGTABLE
766	default y if DEBUG_VM
767	help
768	  This option provides a debug method which can be used to test
769	  architecture page table helper functions on various platforms in
770	  verifying if they comply with expected generic MM semantics. This
771	  will help architecture code in making sure that any changes or
772	  new additions of these helpers still conform to expected
773	  semantics of the generic MM. Platforms will have to opt in for
774	  this through ARCH_HAS_DEBUG_VM_PGTABLE.
775
776	  If unsure, say N.
777
778config ARCH_HAS_DEBUG_VIRTUAL
779	bool
780
781config DEBUG_VIRTUAL
782	bool "Debug VM translations"
783	depends on DEBUG_KERNEL && ARCH_HAS_DEBUG_VIRTUAL
784	help
785	  Enable some costly sanity checks in virtual to page code. This can
786	  catch mistakes with virt_to_page() and friends.
787
788	  If unsure, say N.
789
790config DEBUG_NOMMU_REGIONS
791	bool "Debug the global anon/private NOMMU mapping region tree"
792	depends on DEBUG_KERNEL && !MMU
793	help
794	  This option causes the global tree of anonymous and private mapping
795	  regions to be regularly checked for invalid topology.
796
797config DEBUG_MEMORY_INIT
798	bool "Debug memory initialisation" if EXPERT
799	default !EXPERT
800	help
801	  Enable this for additional checks during memory initialisation.
802	  The sanity checks verify aspects of the VM such as the memory model
803	  and other information provided by the architecture. Verbose
804	  information will be printed at KERN_DEBUG loglevel depending
805	  on the mminit_loglevel= command-line option.
806
807	  If unsure, say Y
808
809config MEMORY_NOTIFIER_ERROR_INJECT
810	tristate "Memory hotplug notifier error injection module"
811	depends on MEMORY_HOTPLUG_SPARSE && NOTIFIER_ERROR_INJECTION
812	help
813	  This option provides the ability to inject artificial errors to
814	  memory hotplug notifier chain callbacks.  It is controlled through
815	  debugfs interface under /sys/kernel/debug/notifier-error-inject/memory
816
817	  If the notifier call chain should be failed with some events
818	  notified, write the error code to "actions/<notifier event>/error".
819
820	  Example: Inject memory hotplug offline error (-12 == -ENOMEM)
821
822	  # cd /sys/kernel/debug/notifier-error-inject/memory
823	  # echo -12 > actions/MEM_GOING_OFFLINE/error
824	  # echo offline > /sys/devices/system/memory/memoryXXX/state
825	  bash: echo: write error: Cannot allocate memory
826
827	  To compile this code as a module, choose M here: the module will
828	  be called memory-notifier-error-inject.
829
830	  If unsure, say N.
831
832config DEBUG_PER_CPU_MAPS
833	bool "Debug access to per_cpu maps"
834	depends on DEBUG_KERNEL
835	depends on SMP
836	help
837	  Say Y to verify that the per_cpu map being accessed has
838	  been set up. This adds a fair amount of code to kernel memory
839	  and decreases performance.
840
841	  Say N if unsure.
842
843config DEBUG_HIGHMEM
844	bool "Highmem debugging"
845	depends on DEBUG_KERNEL && HIGHMEM
846	help
847	  This option enables additional error checking for high memory
848	  systems.  Disable for production systems.
849
850config HAVE_DEBUG_STACKOVERFLOW
851	bool
852
853config DEBUG_STACKOVERFLOW
854	bool "Check for stack overflows"
855	depends on DEBUG_KERNEL && HAVE_DEBUG_STACKOVERFLOW
856	help
857	  Say Y here if you want to check for overflows of kernel, IRQ
858	  and exception stacks (if your architecture uses them). This
859	  option will show detailed messages if free stack space drops
860	  below a certain limit.
861
862	  These kinds of bugs usually occur when call-chains in the
863	  kernel get too deep, especially when interrupts are
864	  involved.
865
866	  Use this in cases where you see apparently random memory
867	  corruption, especially if it appears in 'struct thread_info'
868
869	  If in doubt, say "N".
870
871source "lib/Kconfig.kasan"
872
873endmenu # "Memory Debugging"
874
875config DEBUG_SHIRQ
876	bool "Debug shared IRQ handlers"
877	depends on DEBUG_KERNEL
878	help
879	  Enable this to generate a spurious interrupt just before a shared
880	  interrupt handler is deregistered (generating one when registering
881	  is currently disabled). Drivers need to handle this correctly. Some
882	  don't and need to be caught.
883
884menu "Debug Oops, Lockups and Hangs"
885
886config PANIC_ON_OOPS
887	bool "Panic on Oops"
888	help
889	  Say Y here to enable the kernel to panic when it oopses. This
890	  has the same effect as setting oops=panic on the kernel command
891	  line.
892
893	  This feature is useful to ensure that the kernel does not do
894	  anything erroneous after an oops which could result in data
895	  corruption or other issues.
896
897	  Say N if unsure.
898
899config PANIC_ON_OOPS_VALUE
900	int
901	range 0 1
902	default 0 if !PANIC_ON_OOPS
903	default 1 if PANIC_ON_OOPS
904
905config PANIC_TIMEOUT
906	int "panic timeout"
907	default 0
908	help
909	  Set the timeout value (in seconds) until a reboot occurs when the
910	  the kernel panics. If n = 0, then we wait forever. A timeout
911	  value n > 0 will wait n seconds before rebooting, while a timeout
912	  value n < 0 will reboot immediately.
913
914config LOCKUP_DETECTOR
915	bool
916
917config SOFTLOCKUP_DETECTOR
918	bool "Detect Soft Lockups"
919	depends on DEBUG_KERNEL && !S390
920	select LOCKUP_DETECTOR
921	help
922	  Say Y here to enable the kernel to act as a watchdog to detect
923	  soft lockups.
924
925	  Softlockups are bugs that cause the kernel to loop in kernel
926	  mode for more than 20 seconds, without giving other tasks a
927	  chance to run.  The current stack trace is displayed upon
928	  detection and the system will stay locked up.
929
930config BOOTPARAM_SOFTLOCKUP_PANIC
931	bool "Panic (Reboot) On Soft Lockups"
932	depends on SOFTLOCKUP_DETECTOR
933	help
934	  Say Y here to enable the kernel to panic on "soft lockups",
935	  which are bugs that cause the kernel to loop in kernel
936	  mode for more than 20 seconds (configurable using the watchdog_thresh
937	  sysctl), without giving other tasks a chance to run.
938
939	  The panic can be used in combination with panic_timeout,
940	  to cause the system to reboot automatically after a
941	  lockup has been detected. This feature is useful for
942	  high-availability systems that have uptime guarantees and
943	  where a lockup must be resolved ASAP.
944
945	  Say N if unsure.
946
947config BOOTPARAM_SOFTLOCKUP_PANIC_VALUE
948	int
949	depends on SOFTLOCKUP_DETECTOR
950	range 0 1
951	default 0 if !BOOTPARAM_SOFTLOCKUP_PANIC
952	default 1 if BOOTPARAM_SOFTLOCKUP_PANIC
953
954config HARDLOCKUP_DETECTOR_PERF
955	bool
956	select SOFTLOCKUP_DETECTOR
957
958#
959# Enables a timestamp based low pass filter to compensate for perf based
960# hard lockup detection which runs too fast due to turbo modes.
961#
962config HARDLOCKUP_CHECK_TIMESTAMP
963	bool
964
965#
966# arch/ can define HAVE_HARDLOCKUP_DETECTOR_ARCH to provide their own hard
967# lockup detector rather than the perf based detector.
968#
969config HARDLOCKUP_DETECTOR
970	bool "Detect Hard Lockups"
971	depends on DEBUG_KERNEL && !S390
972	depends on HAVE_HARDLOCKUP_DETECTOR_PERF || HAVE_HARDLOCKUP_DETECTOR_ARCH
973	select LOCKUP_DETECTOR
974	select HARDLOCKUP_DETECTOR_PERF if HAVE_HARDLOCKUP_DETECTOR_PERF
975	select HARDLOCKUP_DETECTOR_ARCH if HAVE_HARDLOCKUP_DETECTOR_ARCH
976	help
977	  Say Y here to enable the kernel to act as a watchdog to detect
978	  hard lockups.
979
980	  Hardlockups are bugs that cause the CPU to loop in kernel mode
981	  for more than 10 seconds, without letting other interrupts have a
982	  chance to run.  The current stack trace is displayed upon detection
983	  and the system will stay locked up.
984
985config BOOTPARAM_HARDLOCKUP_PANIC
986	bool "Panic (Reboot) On Hard Lockups"
987	depends on HARDLOCKUP_DETECTOR
988	help
989	  Say Y here to enable the kernel to panic on "hard lockups",
990	  which are bugs that cause the kernel to loop in kernel
991	  mode with interrupts disabled for more than 10 seconds (configurable
992	  using the watchdog_thresh sysctl).
993
994	  Say N if unsure.
995
996config BOOTPARAM_HARDLOCKUP_PANIC_VALUE
997	int
998	depends on HARDLOCKUP_DETECTOR
999	range 0 1
1000	default 0 if !BOOTPARAM_HARDLOCKUP_PANIC
1001	default 1 if BOOTPARAM_HARDLOCKUP_PANIC
1002
1003config DETECT_HUNG_TASK
1004	bool "Detect Hung Tasks"
1005	depends on DEBUG_KERNEL
1006	default SOFTLOCKUP_DETECTOR
1007	help
1008	  Say Y here to enable the kernel to detect "hung tasks",
1009	  which are bugs that cause the task to be stuck in
1010	  uninterruptible "D" state indefinitely.
1011
1012	  When a hung task is detected, the kernel will print the
1013	  current stack trace (which you should report), but the
1014	  task will stay in uninterruptible state. If lockdep is
1015	  enabled then all held locks will also be reported. This
1016	  feature has negligible overhead.
1017
1018config DEFAULT_HUNG_TASK_TIMEOUT
1019	int "Default timeout for hung task detection (in seconds)"
1020	depends on DETECT_HUNG_TASK
1021	default 120
1022	help
1023	  This option controls the default timeout (in seconds) used
1024	  to determine when a task has become non-responsive and should
1025	  be considered hung.
1026
1027	  It can be adjusted at runtime via the kernel.hung_task_timeout_secs
1028	  sysctl or by writing a value to
1029	  /proc/sys/kernel/hung_task_timeout_secs.
1030
1031	  A timeout of 0 disables the check.  The default is two minutes.
1032	  Keeping the default should be fine in most cases.
1033
1034config BOOTPARAM_HUNG_TASK_PANIC
1035	bool "Panic (Reboot) On Hung Tasks"
1036	depends on DETECT_HUNG_TASK
1037	help
1038	  Say Y here to enable the kernel to panic on "hung tasks",
1039	  which are bugs that cause the kernel to leave a task stuck
1040	  in uninterruptible "D" state.
1041
1042	  The panic can be used in combination with panic_timeout,
1043	  to cause the system to reboot automatically after a
1044	  hung task has been detected. This feature is useful for
1045	  high-availability systems that have uptime guarantees and
1046	  where a hung tasks must be resolved ASAP.
1047
1048	  Say N if unsure.
1049
1050config BOOTPARAM_HUNG_TASK_PANIC_VALUE
1051	int
1052	depends on DETECT_HUNG_TASK
1053	range 0 1
1054	default 0 if !BOOTPARAM_HUNG_TASK_PANIC
1055	default 1 if BOOTPARAM_HUNG_TASK_PANIC
1056
1057config WQ_WATCHDOG
1058	bool "Detect Workqueue Stalls"
1059	depends on DEBUG_KERNEL
1060	help
1061	  Say Y here to enable stall detection on workqueues.  If a
1062	  worker pool doesn't make forward progress on a pending work
1063	  item for over a given amount of time, 30s by default, a
1064	  warning message is printed along with dump of workqueue
1065	  state.  This can be configured through kernel parameter
1066	  "workqueue.watchdog_thresh" and its sysfs counterpart.
1067
1068config TEST_LOCKUP
1069	tristate "Test module to generate lockups"
1070	help
1071	  This builds the "test_lockup" module that helps to make sure
1072	  that watchdogs and lockup detectors are working properly.
1073
1074	  Depending on module parameters it could emulate soft or hard
1075	  lockup, "hung task", or locking arbitrary lock for a long time.
1076	  Also it could generate series of lockups with cooling-down periods.
1077
1078	  If unsure, say N.
1079
1080endmenu # "Debug lockups and hangs"
1081
1082menu "Scheduler Debugging"
1083
1084config SCHED_DEBUG
1085	bool "Collect scheduler debugging info"
1086	depends on DEBUG_KERNEL && PROC_FS
1087	default y
1088	help
1089	  If you say Y here, the /proc/sched_debug file will be provided
1090	  that can help debug the scheduler. The runtime overhead of this
1091	  option is minimal.
1092
1093config SCHED_INFO
1094	bool
1095	default n
1096
1097config SCHEDSTATS
1098	bool "Collect scheduler statistics"
1099	depends on DEBUG_KERNEL && PROC_FS
1100	select SCHED_INFO
1101	help
1102	  If you say Y here, additional code will be inserted into the
1103	  scheduler and related routines to collect statistics about
1104	  scheduler behavior and provide them in /proc/schedstat.  These
1105	  stats may be useful for both tuning and debugging the scheduler
1106	  If you aren't debugging the scheduler or trying to tune a specific
1107	  application, you can say N to avoid the very slight overhead
1108	  this adds.
1109
1110endmenu
1111
1112config DEBUG_TIMEKEEPING
1113	bool "Enable extra timekeeping sanity checking"
1114	help
1115	  This option will enable additional timekeeping sanity checks
1116	  which may be helpful when diagnosing issues where timekeeping
1117	  problems are suspected.
1118
1119	  This may include checks in the timekeeping hotpaths, so this
1120	  option may have a (very small) performance impact to some
1121	  workloads.
1122
1123	  If unsure, say N.
1124
1125config DEBUG_PREEMPT
1126	bool "Debug preemptible kernel"
1127	depends on DEBUG_KERNEL && PREEMPTION && TRACE_IRQFLAGS_SUPPORT
1128	default y
1129	help
1130	  If you say Y here then the kernel will use a debug variant of the
1131	  commonly used smp_processor_id() function and will print warnings
1132	  if kernel code uses it in a preemption-unsafe way. Also, the kernel
1133	  will detect preemption count underflows.
1134
1135menu "Lock Debugging (spinlocks, mutexes, etc...)"
1136
1137config LOCK_DEBUGGING_SUPPORT
1138	bool
1139	depends on TRACE_IRQFLAGS_SUPPORT && STACKTRACE_SUPPORT && LOCKDEP_SUPPORT
1140	default y
1141
1142config PROVE_LOCKING
1143	bool "Lock debugging: prove locking correctness"
1144	depends on DEBUG_KERNEL && LOCK_DEBUGGING_SUPPORT
1145	select LOCKDEP
1146	select DEBUG_SPINLOCK
1147	select DEBUG_MUTEXES
1148	select DEBUG_RT_MUTEXES if RT_MUTEXES
1149	select DEBUG_RWSEMS
1150	select DEBUG_WW_MUTEX_SLOWPATH
1151	select DEBUG_LOCK_ALLOC
1152	select PREEMPT_COUNT if !ARCH_NO_PREEMPT
1153	select TRACE_IRQFLAGS
1154	default n
1155	help
1156	 This feature enables the kernel to prove that all locking
1157	 that occurs in the kernel runtime is mathematically
1158	 correct: that under no circumstance could an arbitrary (and
1159	 not yet triggered) combination of observed locking
1160	 sequences (on an arbitrary number of CPUs, running an
1161	 arbitrary number of tasks and interrupt contexts) cause a
1162	 deadlock.
1163
1164	 In short, this feature enables the kernel to report locking
1165	 related deadlocks before they actually occur.
1166
1167	 The proof does not depend on how hard and complex a
1168	 deadlock scenario would be to trigger: how many
1169	 participant CPUs, tasks and irq-contexts would be needed
1170	 for it to trigger. The proof also does not depend on
1171	 timing: if a race and a resulting deadlock is possible
1172	 theoretically (no matter how unlikely the race scenario
1173	 is), it will be proven so and will immediately be
1174	 reported by the kernel (once the event is observed that
1175	 makes the deadlock theoretically possible).
1176
1177	 If a deadlock is impossible (i.e. the locking rules, as
1178	 observed by the kernel, are mathematically correct), the
1179	 kernel reports nothing.
1180
1181	 NOTE: this feature can also be enabled for rwlocks, mutexes
1182	 and rwsems - in which case all dependencies between these
1183	 different locking variants are observed and mapped too, and
1184	 the proof of observed correctness is also maintained for an
1185	 arbitrary combination of these separate locking variants.
1186
1187	 For more details, see Documentation/locking/lockdep-design.rst.
1188
1189config PROVE_RAW_LOCK_NESTING
1190	bool "Enable raw_spinlock - spinlock nesting checks"
1191	depends on PROVE_LOCKING
1192	default n
1193	help
1194	 Enable the raw_spinlock vs. spinlock nesting checks which ensure
1195	 that the lock nesting rules for PREEMPT_RT enabled kernels are
1196	 not violated.
1197
1198	 NOTE: There are known nesting problems. So if you enable this
1199	 option expect lockdep splats until these problems have been fully
1200	 addressed which is work in progress. This config switch allows to
1201	 identify and analyze these problems. It will be removed and the
1202	 check permanentely enabled once the main issues have been fixed.
1203
1204	 If unsure, select N.
1205
1206config LOCK_STAT
1207	bool "Lock usage statistics"
1208	depends on DEBUG_KERNEL && LOCK_DEBUGGING_SUPPORT
1209	select LOCKDEP
1210	select DEBUG_SPINLOCK
1211	select DEBUG_MUTEXES
1212	select DEBUG_RT_MUTEXES if RT_MUTEXES
1213	select DEBUG_LOCK_ALLOC
1214	default n
1215	help
1216	 This feature enables tracking lock contention points
1217
1218	 For more details, see Documentation/locking/lockstat.rst
1219
1220	 This also enables lock events required by "perf lock",
1221	 subcommand of perf.
1222	 If you want to use "perf lock", you also need to turn on
1223	 CONFIG_EVENT_TRACING.
1224
1225	 CONFIG_LOCK_STAT defines "contended" and "acquired" lock events.
1226	 (CONFIG_LOCKDEP defines "acquire" and "release" events.)
1227
1228config DEBUG_RT_MUTEXES
1229	bool "RT Mutex debugging, deadlock detection"
1230	depends on DEBUG_KERNEL && RT_MUTEXES
1231	help
1232	 This allows rt mutex semantics violations and rt mutex related
1233	 deadlocks (lockups) to be detected and reported automatically.
1234
1235config DEBUG_SPINLOCK
1236	bool "Spinlock and rw-lock debugging: basic checks"
1237	depends on DEBUG_KERNEL
1238	select UNINLINE_SPIN_UNLOCK
1239	help
1240	  Say Y here and build SMP to catch missing spinlock initialization
1241	  and certain other kinds of spinlock errors commonly made.  This is
1242	  best used in conjunction with the NMI watchdog so that spinlock
1243	  deadlocks are also debuggable.
1244
1245config DEBUG_MUTEXES
1246	bool "Mutex debugging: basic checks"
1247	depends on DEBUG_KERNEL
1248	help
1249	 This feature allows mutex semantics violations to be detected and
1250	 reported.
1251
1252config DEBUG_WW_MUTEX_SLOWPATH
1253	bool "Wait/wound mutex debugging: Slowpath testing"
1254	depends on DEBUG_KERNEL && LOCK_DEBUGGING_SUPPORT
1255	select DEBUG_LOCK_ALLOC
1256	select DEBUG_SPINLOCK
1257	select DEBUG_MUTEXES
1258	help
1259	 This feature enables slowpath testing for w/w mutex users by
1260	 injecting additional -EDEADLK wound/backoff cases. Together with
1261	 the full mutex checks enabled with (CONFIG_PROVE_LOCKING) this
1262	 will test all possible w/w mutex interface abuse with the
1263	 exception of simply not acquiring all the required locks.
1264	 Note that this feature can introduce significant overhead, so
1265	 it really should not be enabled in a production or distro kernel,
1266	 even a debug kernel.  If you are a driver writer, enable it.  If
1267	 you are a distro, do not.
1268
1269config DEBUG_RWSEMS
1270	bool "RW Semaphore debugging: basic checks"
1271	depends on DEBUG_KERNEL
1272	help
1273	  This debugging feature allows mismatched rw semaphore locks
1274	  and unlocks to be detected and reported.
1275
1276config DEBUG_LOCK_ALLOC
1277	bool "Lock debugging: detect incorrect freeing of live locks"
1278	depends on DEBUG_KERNEL && LOCK_DEBUGGING_SUPPORT
1279	select DEBUG_SPINLOCK
1280	select DEBUG_MUTEXES
1281	select DEBUG_RT_MUTEXES if RT_MUTEXES
1282	select LOCKDEP
1283	help
1284	 This feature will check whether any held lock (spinlock, rwlock,
1285	 mutex or rwsem) is incorrectly freed by the kernel, via any of the
1286	 memory-freeing routines (kfree(), kmem_cache_free(), free_pages(),
1287	 vfree(), etc.), whether a live lock is incorrectly reinitialized via
1288	 spin_lock_init()/mutex_init()/etc., or whether there is any lock
1289	 held during task exit.
1290
1291config LOCKDEP
1292	bool
1293	depends on DEBUG_KERNEL && LOCK_DEBUGGING_SUPPORT
1294	select STACKTRACE
1295	select FRAME_POINTER if !MIPS && !PPC && !ARM && !S390 && !MICROBLAZE && !ARC && !X86
1296	select KALLSYMS
1297	select KALLSYMS_ALL
1298
1299config LOCKDEP_SMALL
1300	bool
1301
1302config DEBUG_LOCKDEP
1303	bool "Lock dependency engine debugging"
1304	depends on DEBUG_KERNEL && LOCKDEP
1305	help
1306	  If you say Y here, the lock dependency engine will do
1307	  additional runtime checks to debug itself, at the price
1308	  of more runtime overhead.
1309
1310config DEBUG_ATOMIC_SLEEP
1311	bool "Sleep inside atomic section checking"
1312	select PREEMPT_COUNT
1313	depends on DEBUG_KERNEL
1314	depends on !ARCH_NO_PREEMPT
1315	help
1316	  If you say Y here, various routines which may sleep will become very
1317	  noisy if they are called inside atomic sections: when a spinlock is
1318	  held, inside an rcu read side critical section, inside preempt disabled
1319	  sections, inside an interrupt, etc...
1320
1321config DEBUG_LOCKING_API_SELFTESTS
1322	bool "Locking API boot-time self-tests"
1323	depends on DEBUG_KERNEL
1324	help
1325	  Say Y here if you want the kernel to run a short self-test during
1326	  bootup. The self-test checks whether common types of locking bugs
1327	  are detected by debugging mechanisms or not. (if you disable
1328	  lock debugging then those bugs wont be detected of course.)
1329	  The following locking APIs are covered: spinlocks, rwlocks,
1330	  mutexes and rwsems.
1331
1332config LOCK_TORTURE_TEST
1333	tristate "torture tests for locking"
1334	depends on DEBUG_KERNEL
1335	select TORTURE_TEST
1336	help
1337	  This option provides a kernel module that runs torture tests
1338	  on kernel locking primitives.  The kernel module may be built
1339	  after the fact on the running kernel to be tested, if desired.
1340
1341	  Say Y here if you want kernel locking-primitive torture tests
1342	  to be built into the kernel.
1343	  Say M if you want these torture tests to build as a module.
1344	  Say N if you are unsure.
1345
1346config WW_MUTEX_SELFTEST
1347	tristate "Wait/wound mutex selftests"
1348	help
1349	  This option provides a kernel module that runs tests on the
1350	  on the struct ww_mutex locking API.
1351
1352	  It is recommended to enable DEBUG_WW_MUTEX_SLOWPATH in conjunction
1353	  with this test harness.
1354
1355	  Say M if you want these self tests to build as a module.
1356	  Say N if you are unsure.
1357
1358endmenu # lock debugging
1359
1360config TRACE_IRQFLAGS
1361	depends on TRACE_IRQFLAGS_SUPPORT
1362	bool
1363	help
1364	  Enables hooks to interrupt enabling and disabling for
1365	  either tracing or lock debugging.
1366
1367config TRACE_IRQFLAGS_NMI
1368	def_bool y
1369	depends on TRACE_IRQFLAGS
1370	depends on TRACE_IRQFLAGS_NMI_SUPPORT
1371
1372config STACKTRACE
1373	bool "Stack backtrace support"
1374	depends on STACKTRACE_SUPPORT
1375	help
1376	  This option causes the kernel to create a /proc/pid/stack for
1377	  every process, showing its current stack trace.
1378	  It is also used by various kernel debugging features that require
1379	  stack trace generation.
1380
1381config WARN_ALL_UNSEEDED_RANDOM
1382	bool "Warn for all uses of unseeded randomness"
1383	default n
1384	help
1385	  Some parts of the kernel contain bugs relating to their use of
1386	  cryptographically secure random numbers before it's actually possible
1387	  to generate those numbers securely. This setting ensures that these
1388	  flaws don't go unnoticed, by enabling a message, should this ever
1389	  occur. This will allow people with obscure setups to know when things
1390	  are going wrong, so that they might contact developers about fixing
1391	  it.
1392
1393	  Unfortunately, on some models of some architectures getting
1394	  a fully seeded CRNG is extremely difficult, and so this can
1395	  result in dmesg getting spammed for a surprisingly long
1396	  time.  This is really bad from a security perspective, and
1397	  so architecture maintainers really need to do what they can
1398	  to get the CRNG seeded sooner after the system is booted.
1399	  However, since users cannot do anything actionable to
1400	  address this, by default the kernel will issue only a single
1401	  warning for the first use of unseeded randomness.
1402
1403	  Say Y here if you want to receive warnings for all uses of
1404	  unseeded randomness.  This will be of use primarily for
1405	  those developers interested in improving the security of
1406	  Linux kernels running on their architecture (or
1407	  subarchitecture).
1408
1409config DEBUG_KOBJECT
1410	bool "kobject debugging"
1411	depends on DEBUG_KERNEL
1412	help
1413	  If you say Y here, some extra kobject debugging messages will be sent
1414	  to the syslog.
1415
1416config DEBUG_KOBJECT_RELEASE
1417	bool "kobject release debugging"
1418	depends on DEBUG_OBJECTS_TIMERS
1419	help
1420	  kobjects are reference counted objects.  This means that their
1421	  last reference count put is not predictable, and the kobject can
1422	  live on past the point at which a driver decides to drop it's
1423	  initial reference to the kobject gained on allocation.  An
1424	  example of this would be a struct device which has just been
1425	  unregistered.
1426
1427	  However, some buggy drivers assume that after such an operation,
1428	  the memory backing the kobject can be immediately freed.  This
1429	  goes completely against the principles of a refcounted object.
1430
1431	  If you say Y here, the kernel will delay the release of kobjects
1432	  on the last reference count to improve the visibility of this
1433	  kind of kobject release bug.
1434
1435config HAVE_DEBUG_BUGVERBOSE
1436	bool
1437
1438menu "Debug kernel data structures"
1439
1440config DEBUG_LIST
1441	bool "Debug linked list manipulation"
1442	depends on DEBUG_KERNEL || BUG_ON_DATA_CORRUPTION
1443	help
1444	  Enable this to turn on extended checks in the linked-list
1445	  walking routines.
1446
1447	  If unsure, say N.
1448
1449config DEBUG_PLIST
1450	bool "Debug priority linked list manipulation"
1451	depends on DEBUG_KERNEL
1452	help
1453	  Enable this to turn on extended checks in the priority-ordered
1454	  linked-list (plist) walking routines.  This checks the entire
1455	  list multiple times during each manipulation.
1456
1457	  If unsure, say N.
1458
1459config DEBUG_SG
1460	bool "Debug SG table operations"
1461	depends on DEBUG_KERNEL
1462	help
1463	  Enable this to turn on checks on scatter-gather tables. This can
1464	  help find problems with drivers that do not properly initialize
1465	  their sg tables.
1466
1467	  If unsure, say N.
1468
1469config DEBUG_NOTIFIERS
1470	bool "Debug notifier call chains"
1471	depends on DEBUG_KERNEL
1472	help
1473	  Enable this to turn on sanity checking for notifier call chains.
1474	  This is most useful for kernel developers to make sure that
1475	  modules properly unregister themselves from notifier chains.
1476	  This is a relatively cheap check but if you care about maximum
1477	  performance, say N.
1478
1479config BUG_ON_DATA_CORRUPTION
1480	bool "Trigger a BUG when data corruption is detected"
1481	select DEBUG_LIST
1482	help
1483	  Select this option if the kernel should BUG when it encounters
1484	  data corruption in kernel memory structures when they get checked
1485	  for validity.
1486
1487	  If unsure, say N.
1488
1489endmenu
1490
1491config DEBUG_CREDENTIALS
1492	bool "Debug credential management"
1493	depends on DEBUG_KERNEL
1494	help
1495	  Enable this to turn on some debug checking for credential
1496	  management.  The additional code keeps track of the number of
1497	  pointers from task_structs to any given cred struct, and checks to
1498	  see that this number never exceeds the usage count of the cred
1499	  struct.
1500
1501	  Furthermore, if SELinux is enabled, this also checks that the
1502	  security pointer in the cred struct is never seen to be invalid.
1503
1504	  If unsure, say N.
1505
1506source "kernel/rcu/Kconfig.debug"
1507
1508config DEBUG_WQ_FORCE_RR_CPU
1509	bool "Force round-robin CPU selection for unbound work items"
1510	depends on DEBUG_KERNEL
1511	default n
1512	help
1513	  Workqueue used to implicitly guarantee that work items queued
1514	  without explicit CPU specified are put on the local CPU.  This
1515	  guarantee is no longer true and while local CPU is still
1516	  preferred work items may be put on foreign CPUs.  Kernel
1517	  parameter "workqueue.debug_force_rr_cpu" is added to force
1518	  round-robin CPU selection to flush out usages which depend on the
1519	  now broken guarantee.  This config option enables the debug
1520	  feature by default.  When enabled, memory and cache locality will
1521	  be impacted.
1522
1523config DEBUG_BLOCK_EXT_DEVT
1524	bool "Force extended block device numbers and spread them"
1525	depends on DEBUG_KERNEL
1526	depends on BLOCK
1527	default n
1528	help
1529	  BIG FAT WARNING: ENABLING THIS OPTION MIGHT BREAK BOOTING ON
1530	  SOME DISTRIBUTIONS.  DO NOT ENABLE THIS UNLESS YOU KNOW WHAT
1531	  YOU ARE DOING.  Distros, please enable this and fix whatever
1532	  is broken.
1533
1534	  Conventionally, block device numbers are allocated from
1535	  predetermined contiguous area.  However, extended block area
1536	  may introduce non-contiguous block device numbers.  This
1537	  option forces most block device numbers to be allocated from
1538	  the extended space and spreads them to discover kernel or
1539	  userland code paths which assume predetermined contiguous
1540	  device number allocation.
1541
1542	  Note that turning on this debug option shuffles all the
1543	  device numbers for all IDE and SCSI devices including libata
1544	  ones, so root partition specified using device number
1545	  directly (via rdev or root=MAJ:MIN) won't work anymore.
1546	  Textual device names (root=/dev/sdXn) will continue to work.
1547
1548	  Say N if you are unsure.
1549
1550config CPU_HOTPLUG_STATE_CONTROL
1551	bool "Enable CPU hotplug state control"
1552	depends on DEBUG_KERNEL
1553	depends on HOTPLUG_CPU
1554	default n
1555	help
1556	  Allows to write steps between "offline" and "online" to the CPUs
1557	  sysfs target file so states can be stepped granular. This is a debug
1558	  option for now as the hotplug machinery cannot be stopped and
1559	  restarted at arbitrary points yet.
1560
1561	  Say N if your are unsure.
1562
1563config LATENCYTOP
1564	bool "Latency measuring infrastructure"
1565	depends on DEBUG_KERNEL
1566	depends on STACKTRACE_SUPPORT
1567	depends on PROC_FS
1568	select FRAME_POINTER if !MIPS && !PPC && !S390 && !MICROBLAZE && !ARM && !ARC && !X86
1569	select KALLSYMS
1570	select KALLSYMS_ALL
1571	select STACKTRACE
1572	select SCHEDSTATS
1573	select SCHED_DEBUG
1574	help
1575	  Enable this option if you want to use the LatencyTOP tool
1576	  to find out which userspace is blocking on what kernel operations.
1577
1578source "kernel/trace/Kconfig"
1579
1580config PROVIDE_OHCI1394_DMA_INIT
1581	bool "Remote debugging over FireWire early on boot"
1582	depends on PCI && X86
1583	help
1584	  If you want to debug problems which hang or crash the kernel early
1585	  on boot and the crashing machine has a FireWire port, you can use
1586	  this feature to remotely access the memory of the crashed machine
1587	  over FireWire. This employs remote DMA as part of the OHCI1394
1588	  specification which is now the standard for FireWire controllers.
1589
1590	  With remote DMA, you can monitor the printk buffer remotely using
1591	  firescope and access all memory below 4GB using fireproxy from gdb.
1592	  Even controlling a kernel debugger is possible using remote DMA.
1593
1594	  Usage:
1595
1596	  If ohci1394_dma=early is used as boot parameter, it will initialize
1597	  all OHCI1394 controllers which are found in the PCI config space.
1598
1599	  As all changes to the FireWire bus such as enabling and disabling
1600	  devices cause a bus reset and thereby disable remote DMA for all
1601	  devices, be sure to have the cable plugged and FireWire enabled on
1602	  the debugging host before booting the debug target for debugging.
1603
1604	  This code (~1k) is freed after boot. By then, the firewire stack
1605	  in charge of the OHCI-1394 controllers should be used instead.
1606
1607	  See Documentation/core-api/debugging-via-ohci1394.rst for more information.
1608
1609source "samples/Kconfig"
1610
1611source "lib/Kconfig.kcsan"
1612
1613config ARCH_HAS_DEVMEM_IS_ALLOWED
1614	bool
1615
1616config STRICT_DEVMEM
1617	bool "Filter access to /dev/mem"
1618	depends on MMU && DEVMEM
1619	depends on ARCH_HAS_DEVMEM_IS_ALLOWED
1620	default y if PPC || X86 || ARM64
1621	help
1622	  If this option is disabled, you allow userspace (root) access to all
1623	  of memory, including kernel and userspace memory. Accidental
1624	  access to this is obviously disastrous, but specific access can
1625	  be used by people debugging the kernel. Note that with PAT support
1626	  enabled, even in this case there are restrictions on /dev/mem
1627	  use due to the cache aliasing requirements.
1628
1629	  If this option is switched on, and IO_STRICT_DEVMEM=n, the /dev/mem
1630	  file only allows userspace access to PCI space and the BIOS code and
1631	  data regions.  This is sufficient for dosemu and X and all common
1632	  users of /dev/mem.
1633
1634	  If in doubt, say Y.
1635
1636config IO_STRICT_DEVMEM
1637	bool "Filter I/O access to /dev/mem"
1638	depends on STRICT_DEVMEM
1639	help
1640	  If this option is disabled, you allow userspace (root) access to all
1641	  io-memory regardless of whether a driver is actively using that
1642	  range.  Accidental access to this is obviously disastrous, but
1643	  specific access can be used by people debugging kernel drivers.
1644
1645	  If this option is switched on, the /dev/mem file only allows
1646	  userspace access to *idle* io-memory ranges (see /proc/iomem) This
1647	  may break traditional users of /dev/mem (dosemu, legacy X, etc...)
1648	  if the driver using a given range cannot be disabled.
1649
1650	  If in doubt, say Y.
1651
1652menu "$(SRCARCH) Debugging"
1653
1654source "arch/$(SRCARCH)/Kconfig.debug"
1655
1656endmenu
1657
1658menu "Kernel Testing and Coverage"
1659
1660source "lib/kunit/Kconfig"
1661
1662config NOTIFIER_ERROR_INJECTION
1663	tristate "Notifier error injection"
1664	depends on DEBUG_KERNEL
1665	select DEBUG_FS
1666	help
1667	  This option provides the ability to inject artificial errors to
1668	  specified notifier chain callbacks. It is useful to test the error
1669	  handling of notifier call chain failures.
1670
1671	  Say N if unsure.
1672
1673config PM_NOTIFIER_ERROR_INJECT
1674	tristate "PM notifier error injection module"
1675	depends on PM && NOTIFIER_ERROR_INJECTION
1676	default m if PM_DEBUG
1677	help
1678	  This option provides the ability to inject artificial errors to
1679	  PM notifier chain callbacks.  It is controlled through debugfs
1680	  interface /sys/kernel/debug/notifier-error-inject/pm
1681
1682	  If the notifier call chain should be failed with some events
1683	  notified, write the error code to "actions/<notifier event>/error".
1684
1685	  Example: Inject PM suspend error (-12 = -ENOMEM)
1686
1687	  # cd /sys/kernel/debug/notifier-error-inject/pm/
1688	  # echo -12 > actions/PM_SUSPEND_PREPARE/error
1689	  # echo mem > /sys/power/state
1690	  bash: echo: write error: Cannot allocate memory
1691
1692	  To compile this code as a module, choose M here: the module will
1693	  be called pm-notifier-error-inject.
1694
1695	  If unsure, say N.
1696
1697config OF_RECONFIG_NOTIFIER_ERROR_INJECT
1698	tristate "OF reconfig notifier error injection module"
1699	depends on OF_DYNAMIC && NOTIFIER_ERROR_INJECTION
1700	help
1701	  This option provides the ability to inject artificial errors to
1702	  OF reconfig notifier chain callbacks.  It is controlled
1703	  through debugfs interface under
1704	  /sys/kernel/debug/notifier-error-inject/OF-reconfig/
1705
1706	  If the notifier call chain should be failed with some events
1707	  notified, write the error code to "actions/<notifier event>/error".
1708
1709	  To compile this code as a module, choose M here: the module will
1710	  be called of-reconfig-notifier-error-inject.
1711
1712	  If unsure, say N.
1713
1714config NETDEV_NOTIFIER_ERROR_INJECT
1715	tristate "Netdev notifier error injection module"
1716	depends on NET && NOTIFIER_ERROR_INJECTION
1717	help
1718	  This option provides the ability to inject artificial errors to
1719	  netdevice notifier chain callbacks.  It is controlled through debugfs
1720	  interface /sys/kernel/debug/notifier-error-inject/netdev
1721
1722	  If the notifier call chain should be failed with some events
1723	  notified, write the error code to "actions/<notifier event>/error".
1724
1725	  Example: Inject netdevice mtu change error (-22 = -EINVAL)
1726
1727	  # cd /sys/kernel/debug/notifier-error-inject/netdev
1728	  # echo -22 > actions/NETDEV_CHANGEMTU/error
1729	  # ip link set eth0 mtu 1024
1730	  RTNETLINK answers: Invalid argument
1731
1732	  To compile this code as a module, choose M here: the module will
1733	  be called netdev-notifier-error-inject.
1734
1735	  If unsure, say N.
1736
1737config FUNCTION_ERROR_INJECTION
1738	def_bool y
1739	depends on HAVE_FUNCTION_ERROR_INJECTION && KPROBES
1740
1741config FAULT_INJECTION
1742	bool "Fault-injection framework"
1743	depends on DEBUG_KERNEL
1744	help
1745	  Provide fault-injection framework.
1746	  For more details, see Documentation/fault-injection/.
1747
1748config FAILSLAB
1749	bool "Fault-injection capability for kmalloc"
1750	depends on FAULT_INJECTION
1751	depends on SLAB || SLUB
1752	help
1753	  Provide fault-injection capability for kmalloc.
1754
1755config FAIL_PAGE_ALLOC
1756	bool "Fault-injection capability for alloc_pages()"
1757	depends on FAULT_INJECTION
1758	help
1759	  Provide fault-injection capability for alloc_pages().
1760
1761config FAIL_MAKE_REQUEST
1762	bool "Fault-injection capability for disk IO"
1763	depends on FAULT_INJECTION && BLOCK
1764	help
1765	  Provide fault-injection capability for disk IO.
1766
1767config FAIL_IO_TIMEOUT
1768	bool "Fault-injection capability for faking disk interrupts"
1769	depends on FAULT_INJECTION && BLOCK
1770	help
1771	  Provide fault-injection capability on end IO handling. This
1772	  will make the block layer "forget" an interrupt as configured,
1773	  thus exercising the error handling.
1774
1775	  Only works with drivers that use the generic timeout handling,
1776	  for others it wont do anything.
1777
1778config FAIL_FUTEX
1779	bool "Fault-injection capability for futexes"
1780	select DEBUG_FS
1781	depends on FAULT_INJECTION && FUTEX
1782	help
1783	  Provide fault-injection capability for futexes.
1784
1785config FAULT_INJECTION_DEBUG_FS
1786	bool "Debugfs entries for fault-injection capabilities"
1787	depends on FAULT_INJECTION && SYSFS && DEBUG_FS
1788	help
1789	  Enable configuration of fault-injection capabilities via debugfs.
1790
1791config FAIL_FUNCTION
1792	bool "Fault-injection capability for functions"
1793	depends on FAULT_INJECTION_DEBUG_FS && FUNCTION_ERROR_INJECTION
1794	help
1795	  Provide function-based fault-injection capability.
1796	  This will allow you to override a specific function with a return
1797	  with given return value. As a result, function caller will see
1798	  an error value and have to handle it. This is useful to test the
1799	  error handling in various subsystems.
1800
1801config FAIL_MMC_REQUEST
1802	bool "Fault-injection capability for MMC IO"
1803	depends on FAULT_INJECTION_DEBUG_FS && MMC
1804	help
1805	  Provide fault-injection capability for MMC IO.
1806	  This will make the mmc core return data errors. This is
1807	  useful to test the error handling in the mmc block device
1808	  and to test how the mmc host driver handles retries from
1809	  the block device.
1810
1811config FAULT_INJECTION_STACKTRACE_FILTER
1812	bool "stacktrace filter for fault-injection capabilities"
1813	depends on FAULT_INJECTION_DEBUG_FS && STACKTRACE_SUPPORT
1814	depends on !X86_64
1815	select STACKTRACE
1816	select FRAME_POINTER if !MIPS && !PPC && !S390 && !MICROBLAZE && !ARM && !ARC && !X86
1817	help
1818	  Provide stacktrace filter for fault-injection capabilities
1819
1820config ARCH_HAS_KCOV
1821	bool
1822	help
1823	  An architecture should select this when it can successfully
1824	  build and run with CONFIG_KCOV. This typically requires
1825	  disabling instrumentation for some early boot code.
1826
1827config CC_HAS_SANCOV_TRACE_PC
1828	def_bool $(cc-option,-fsanitize-coverage=trace-pc)
1829
1830
1831config KCOV
1832	bool "Code coverage for fuzzing"
1833	depends on ARCH_HAS_KCOV
1834	depends on CC_HAS_SANCOV_TRACE_PC || GCC_PLUGINS
1835	select DEBUG_FS
1836	select GCC_PLUGIN_SANCOV if !CC_HAS_SANCOV_TRACE_PC
1837	help
1838	  KCOV exposes kernel code coverage information in a form suitable
1839	  for coverage-guided fuzzing (randomized testing).
1840
1841	  If RANDOMIZE_BASE is enabled, PC values will not be stable across
1842	  different machines and across reboots. If you need stable PC values,
1843	  disable RANDOMIZE_BASE.
1844
1845	  For more details, see Documentation/dev-tools/kcov.rst.
1846
1847config KCOV_ENABLE_COMPARISONS
1848	bool "Enable comparison operands collection by KCOV"
1849	depends on KCOV
1850	depends on $(cc-option,-fsanitize-coverage=trace-cmp)
1851	help
1852	  KCOV also exposes operands of every comparison in the instrumented
1853	  code along with operand sizes and PCs of the comparison instructions.
1854	  These operands can be used by fuzzing engines to improve the quality
1855	  of fuzzing coverage.
1856
1857config KCOV_INSTRUMENT_ALL
1858	bool "Instrument all code by default"
1859	depends on KCOV
1860	default y
1861	help
1862	  If you are doing generic system call fuzzing (like e.g. syzkaller),
1863	  then you will want to instrument the whole kernel and you should
1864	  say y here. If you are doing more targeted fuzzing (like e.g.
1865	  filesystem fuzzing with AFL) then you will want to enable coverage
1866	  for more specific subsets of files, and should say n here.
1867
1868config KCOV_IRQ_AREA_SIZE
1869	hex "Size of interrupt coverage collection area in words"
1870	depends on KCOV
1871	default 0x40000
1872	help
1873	  KCOV uses preallocated per-cpu areas to collect coverage from
1874	  soft interrupts. This specifies the size of those areas in the
1875	  number of unsigned long words.
1876
1877menuconfig RUNTIME_TESTING_MENU
1878	bool "Runtime Testing"
1879	def_bool y
1880
1881if RUNTIME_TESTING_MENU
1882
1883config LKDTM
1884	tristate "Linux Kernel Dump Test Tool Module"
1885	depends on DEBUG_FS
1886	help
1887	This module enables testing of the different dumping mechanisms by
1888	inducing system failures at predefined crash points.
1889	If you don't need it: say N
1890	Choose M here to compile this code as a module. The module will be
1891	called lkdtm.
1892
1893	Documentation on how to use the module can be found in
1894	Documentation/fault-injection/provoke-crashes.rst
1895
1896config TEST_LIST_SORT
1897	tristate "Linked list sorting test"
1898	depends on DEBUG_KERNEL || m
1899	help
1900	  Enable this to turn on 'list_sort()' function test. This test is
1901	  executed only once during system boot (so affects only boot time),
1902	  or at module load time.
1903
1904	  If unsure, say N.
1905
1906config TEST_MIN_HEAP
1907	tristate "Min heap test"
1908	depends on DEBUG_KERNEL || m
1909	help
1910	  Enable this to turn on min heap function tests. This test is
1911	  executed only once during system boot (so affects only boot time),
1912	  or at module load time.
1913
1914	  If unsure, say N.
1915
1916config TEST_SORT
1917	tristate "Array-based sort test"
1918	depends on DEBUG_KERNEL || m
1919	help
1920	  This option enables the self-test function of 'sort()' at boot,
1921	  or at module load time.
1922
1923	  If unsure, say N.
1924
1925config KPROBES_SANITY_TEST
1926	bool "Kprobes sanity tests"
1927	depends on DEBUG_KERNEL
1928	depends on KPROBES
1929	help
1930	  This option provides for testing basic kprobes functionality on
1931	  boot. Samples of kprobe and kretprobe are inserted and
1932	  verified for functionality.
1933
1934	  Say N if you are unsure.
1935
1936config BACKTRACE_SELF_TEST
1937	tristate "Self test for the backtrace code"
1938	depends on DEBUG_KERNEL
1939	help
1940	  This option provides a kernel module that can be used to test
1941	  the kernel stack backtrace code. This option is not useful
1942	  for distributions or general kernels, but only for kernel
1943	  developers working on architecture code.
1944
1945	  Note that if you want to also test saved backtraces, you will
1946	  have to enable STACKTRACE as well.
1947
1948	  Say N if you are unsure.
1949
1950config RBTREE_TEST
1951	tristate "Red-Black tree test"
1952	depends on DEBUG_KERNEL
1953	help
1954	  A benchmark measuring the performance of the rbtree library.
1955	  Also includes rbtree invariant checks.
1956
1957config REED_SOLOMON_TEST
1958	tristate "Reed-Solomon library test"
1959	depends on DEBUG_KERNEL || m
1960	select REED_SOLOMON
1961	select REED_SOLOMON_ENC16
1962	select REED_SOLOMON_DEC16
1963	help
1964	  This option enables the self-test function of rslib at boot,
1965	  or at module load time.
1966
1967	  If unsure, say N.
1968
1969config INTERVAL_TREE_TEST
1970	tristate "Interval tree test"
1971	depends on DEBUG_KERNEL
1972	select INTERVAL_TREE
1973	help
1974	  A benchmark measuring the performance of the interval tree library
1975
1976config PERCPU_TEST
1977	tristate "Per cpu operations test"
1978	depends on m && DEBUG_KERNEL
1979	help
1980	  Enable this option to build test module which validates per-cpu
1981	  operations.
1982
1983	  If unsure, say N.
1984
1985config ATOMIC64_SELFTEST
1986	tristate "Perform an atomic64_t self-test"
1987	help
1988	  Enable this option to test the atomic64_t functions at boot or
1989	  at module load time.
1990
1991	  If unsure, say N.
1992
1993config ASYNC_RAID6_TEST
1994	tristate "Self test for hardware accelerated raid6 recovery"
1995	depends on ASYNC_RAID6_RECOV
1996	select ASYNC_MEMCPY
1997	help
1998	  This is a one-shot self test that permutes through the
1999	  recovery of all the possible two disk failure scenarios for a
2000	  N-disk array.  Recovery is performed with the asynchronous
2001	  raid6 recovery routines, and will optionally use an offload
2002	  engine if one is available.
2003
2004	  If unsure, say N.
2005
2006config TEST_HEXDUMP
2007	tristate "Test functions located in the hexdump module at runtime"
2008
2009config TEST_STRING_HELPERS
2010	tristate "Test functions located in the string_helpers module at runtime"
2011
2012config TEST_STRSCPY
2013	tristate "Test strscpy*() family of functions at runtime"
2014
2015config TEST_KSTRTOX
2016	tristate "Test kstrto*() family of functions at runtime"
2017
2018config TEST_PRINTF
2019	tristate "Test printf() family of functions at runtime"
2020
2021config TEST_BITMAP
2022	tristate "Test bitmap_*() family of functions at runtime"
2023	help
2024	  Enable this option to test the bitmap functions at boot.
2025
2026	  If unsure, say N.
2027
2028config TEST_BITFIELD
2029	tristate "Test bitfield functions at runtime"
2030	help
2031	  Enable this option to test the bitfield functions at boot.
2032
2033	  If unsure, say N.
2034
2035config TEST_UUID
2036	tristate "Test functions located in the uuid module at runtime"
2037
2038config TEST_XARRAY
2039	tristate "Test the XArray code at runtime"
2040
2041config TEST_OVERFLOW
2042	tristate "Test check_*_overflow() functions at runtime"
2043
2044config TEST_RHASHTABLE
2045	tristate "Perform selftest on resizable hash table"
2046	help
2047	  Enable this option to test the rhashtable functions at boot.
2048
2049	  If unsure, say N.
2050
2051config TEST_HASH
2052	tristate "Perform selftest on hash functions"
2053	help
2054	  Enable this option to test the kernel's integer (<linux/hash.h>),
2055	  string (<linux/stringhash.h>), and siphash (<linux/siphash.h>)
2056	  hash functions on boot (or module load).
2057
2058	  This is intended to help people writing architecture-specific
2059	  optimized versions.  If unsure, say N.
2060
2061config TEST_IDA
2062	tristate "Perform selftest on IDA functions"
2063
2064config TEST_PARMAN
2065	tristate "Perform selftest on priority array manager"
2066	depends on PARMAN
2067	help
2068	  Enable this option to test priority array manager on boot
2069	  (or module load).
2070
2071	  If unsure, say N.
2072
2073config TEST_IRQ_TIMINGS
2074	bool "IRQ timings selftest"
2075	depends on IRQ_TIMINGS
2076	help
2077	  Enable this option to test the irq timings code on boot.
2078
2079	  If unsure, say N.
2080
2081config TEST_LKM
2082	tristate "Test module loading with 'hello world' module"
2083	depends on m
2084	help
2085	  This builds the "test_module" module that emits "Hello, world"
2086	  on printk when loaded. It is designed to be used for basic
2087	  evaluation of the module loading subsystem (for example when
2088	  validating module verification). It lacks any extra dependencies,
2089	  and will not normally be loaded by the system unless explicitly
2090	  requested by name.
2091
2092	  If unsure, say N.
2093
2094config TEST_BITOPS
2095	tristate "Test module for compilation of bitops operations"
2096	depends on m
2097	help
2098	  This builds the "test_bitops" module that is much like the
2099	  TEST_LKM module except that it does a basic exercise of the
2100	  set/clear_bit macros and get_count_order/long to make sure there are
2101	  no compiler warnings from C=1 sparse checker or -Wextra
2102	  compilations. It has no dependencies and doesn't run or load unless
2103	  explicitly requested by name.  for example: modprobe test_bitops.
2104
2105	  If unsure, say N.
2106
2107config TEST_VMALLOC
2108	tristate "Test module for stress/performance analysis of vmalloc allocator"
2109	default n
2110       depends on MMU
2111	depends on m
2112	help
2113	  This builds the "test_vmalloc" module that should be used for
2114	  stress and performance analysis. So, any new change for vmalloc
2115	  subsystem can be evaluated from performance and stability point
2116	  of view.
2117
2118	  If unsure, say N.
2119
2120config TEST_USER_COPY
2121	tristate "Test user/kernel boundary protections"
2122	depends on m
2123	help
2124	  This builds the "test_user_copy" module that runs sanity checks
2125	  on the copy_to/from_user infrastructure, making sure basic
2126	  user/kernel boundary testing is working. If it fails to load,
2127	  a regression has been detected in the user/kernel memory boundary
2128	  protections.
2129
2130	  If unsure, say N.
2131
2132config TEST_BPF
2133	tristate "Test BPF filter functionality"
2134	depends on m && NET
2135	help
2136	  This builds the "test_bpf" module that runs various test vectors
2137	  against the BPF interpreter or BPF JIT compiler depending on the
2138	  current setting. This is in particular useful for BPF JIT compiler
2139	  development, but also to run regression tests against changes in
2140	  the interpreter code. It also enables test stubs for eBPF maps and
2141	  verifier used by user space verifier testsuite.
2142
2143	  If unsure, say N.
2144
2145config TEST_BLACKHOLE_DEV
2146	tristate "Test blackhole netdev functionality"
2147	depends on m && NET
2148	help
2149	  This builds the "test_blackhole_dev" module that validates the
2150	  data path through this blackhole netdev.
2151
2152	  If unsure, say N.
2153
2154config FIND_BIT_BENCHMARK
2155	tristate "Test find_bit functions"
2156	help
2157	  This builds the "test_find_bit" module that measure find_*_bit()
2158	  functions performance.
2159
2160	  If unsure, say N.
2161
2162config TEST_FIRMWARE
2163	tristate "Test firmware loading via userspace interface"
2164	depends on FW_LOADER
2165	help
2166	  This builds the "test_firmware" module that creates a userspace
2167	  interface for testing firmware loading. This can be used to
2168	  control the triggering of firmware loading without needing an
2169	  actual firmware-using device. The contents can be rechecked by
2170	  userspace.
2171
2172	  If unsure, say N.
2173
2174config TEST_SYSCTL
2175	tristate "sysctl test driver"
2176	depends on PROC_SYSCTL
2177	help
2178	  This builds the "test_sysctl" module. This driver enables to test the
2179	  proc sysctl interfaces available to drivers safely without affecting
2180	  production knobs which might alter system functionality.
2181
2182	  If unsure, say N.
2183
2184config SYSCTL_KUNIT_TEST
2185	tristate "KUnit test for sysctl" if !KUNIT_ALL_TESTS
2186	depends on KUNIT
2187	default KUNIT_ALL_TESTS
2188	help
2189	  This builds the proc sysctl unit test, which runs on boot.
2190	  Tests the API contract and implementation correctness of sysctl.
2191	  For more information on KUnit and unit tests in general please refer
2192	  to the KUnit documentation in Documentation/dev-tools/kunit/.
2193
2194	  If unsure, say N.
2195
2196config LIST_KUNIT_TEST
2197	tristate "KUnit Test for Kernel Linked-list structures" if !KUNIT_ALL_TESTS
2198	depends on KUNIT
2199	default KUNIT_ALL_TESTS
2200	help
2201	  This builds the linked list KUnit test suite.
2202	  It tests that the API and basic functionality of the list_head type
2203	  and associated macros.
2204
2205	  KUnit tests run during boot and output the results to the debug log
2206	  in TAP format (http://testanything.org/). Only useful for kernel devs
2207	  running the KUnit test harness, and not intended for inclusion into a
2208	  production build.
2209
2210	  For more information on KUnit and unit tests in general please refer
2211	  to the KUnit documentation in Documentation/dev-tools/kunit/.
2212
2213	  If unsure, say N.
2214
2215config LINEAR_RANGES_TEST
2216	tristate "KUnit test for linear_ranges"
2217	depends on KUNIT
2218	select LINEAR_RANGES
2219	help
2220	  This builds the linear_ranges unit test, which runs on boot.
2221	  Tests the linear_ranges logic correctness.
2222	  For more information on KUnit and unit tests in general please refer
2223	  to the KUnit documentation in Documentation/dev-tools/kunit/.
2224
2225	  If unsure, say N.
2226
2227config TEST_UDELAY
2228	tristate "udelay test driver"
2229	help
2230	  This builds the "udelay_test" module that helps to make sure
2231	  that udelay() is working properly.
2232
2233	  If unsure, say N.
2234
2235config TEST_STATIC_KEYS
2236	tristate "Test static keys"
2237	depends on m
2238	help
2239	  Test the static key interfaces.
2240
2241	  If unsure, say N.
2242
2243config TEST_KMOD
2244	tristate "kmod stress tester"
2245	depends on m
2246	depends on NETDEVICES && NET_CORE && INET # for TUN
2247	depends on BLOCK
2248	select TEST_LKM
2249	select XFS_FS
2250	select TUN
2251	select BTRFS_FS
2252	help
2253	  Test the kernel's module loading mechanism: kmod. kmod implements
2254	  support to load modules using the Linux kernel's usermode helper.
2255	  This test provides a series of tests against kmod.
2256
2257	  Although technically you can either build test_kmod as a module or
2258	  into the kernel we disallow building it into the kernel since
2259	  it stress tests request_module() and this will very likely cause
2260	  some issues by taking over precious threads available from other
2261	  module load requests, ultimately this could be fatal.
2262
2263	  To run tests run:
2264
2265	  tools/testing/selftests/kmod/kmod.sh --help
2266
2267	  If unsure, say N.
2268
2269config TEST_DEBUG_VIRTUAL
2270	tristate "Test CONFIG_DEBUG_VIRTUAL feature"
2271	depends on DEBUG_VIRTUAL
2272	help
2273	  Test the kernel's ability to detect incorrect calls to
2274	  virt_to_phys() done against the non-linear part of the
2275	  kernel's virtual address map.
2276
2277	  If unsure, say N.
2278
2279config TEST_MEMCAT_P
2280	tristate "Test memcat_p() helper function"
2281	help
2282	  Test the memcat_p() helper for correctly merging two
2283	  pointer arrays together.
2284
2285	  If unsure, say N.
2286
2287config TEST_LIVEPATCH
2288	tristate "Test livepatching"
2289	default n
2290	depends on DYNAMIC_DEBUG
2291	depends on LIVEPATCH
2292	depends on m
2293	help
2294	  Test kernel livepatching features for correctness.  The tests will
2295	  load test modules that will be livepatched in various scenarios.
2296
2297	  To run all the livepatching tests:
2298
2299	  make -C tools/testing/selftests TARGETS=livepatch run_tests
2300
2301	  Alternatively, individual tests may be invoked:
2302
2303	  tools/testing/selftests/livepatch/test-callbacks.sh
2304	  tools/testing/selftests/livepatch/test-livepatch.sh
2305	  tools/testing/selftests/livepatch/test-shadow-vars.sh
2306
2307	  If unsure, say N.
2308
2309config TEST_OBJAGG
2310	tristate "Perform selftest on object aggreration manager"
2311	default n
2312	depends on OBJAGG
2313	help
2314	  Enable this option to test object aggregation manager on boot
2315	  (or module load).
2316
2317
2318config TEST_STACKINIT
2319	tristate "Test level of stack variable initialization"
2320	help
2321	  Test if the kernel is zero-initializing stack variables and
2322	  padding. Coverage is controlled by compiler flags,
2323	  CONFIG_GCC_PLUGIN_STRUCTLEAK, CONFIG_GCC_PLUGIN_STRUCTLEAK_BYREF,
2324	  or CONFIG_GCC_PLUGIN_STRUCTLEAK_BYREF_ALL.
2325
2326	  If unsure, say N.
2327
2328config TEST_MEMINIT
2329	tristate "Test heap/page initialization"
2330	help
2331	  Test if the kernel is zero-initializing heap and page allocations.
2332	  This can be useful to test init_on_alloc and init_on_free features.
2333
2334	  If unsure, say N.
2335
2336config TEST_HMM
2337	tristate "Test HMM (Heterogeneous Memory Management)"
2338	depends on TRANSPARENT_HUGEPAGE
2339	depends on DEVICE_PRIVATE
2340	select HMM_MIRROR
2341	select MMU_NOTIFIER
2342	help
2343	  This is a pseudo device driver solely for testing HMM.
2344	  Say M here if you want to build the HMM test module.
2345	  Doing so will allow you to run tools/testing/selftest/vm/hmm-tests.
2346
2347	  If unsure, say N.
2348
2349config TEST_FPU
2350	tristate "Test floating point operations in kernel space"
2351	depends on X86 && !KCOV_INSTRUMENT_ALL
2352	help
2353	  Enable this option to add /sys/kernel/debug/selftest_helpers/test_fpu
2354	  which will trigger a sequence of floating point operations. This is used
2355	  for self-testing floating point control register setting in
2356	  kernel_fpu_begin().
2357
2358	  If unsure, say N.
2359
2360endif # RUNTIME_TESTING_MENU
2361
2362config MEMTEST
2363	bool "Memtest"
2364	help
2365	  This option adds a kernel parameter 'memtest', which allows memtest
2366	  to be set.
2367	        memtest=0, mean disabled; -- default
2368	        memtest=1, mean do 1 test pattern;
2369	        ...
2370	        memtest=17, mean do 17 test patterns.
2371	  If you are unsure how to answer this question, answer N.
2372
2373
2374
2375config HYPERV_TESTING
2376	bool "Microsoft Hyper-V driver testing"
2377	default n
2378	depends on HYPERV && DEBUG_FS
2379	help
2380	  Select this option to enable Hyper-V vmbus testing.
2381
2382endmenu # "Kernel Testing and Coverage"
2383
2384endmenu # Kernel hacking
2385