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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 STACKTRACE_BUILD_ID
39	bool "Show build ID information in stacktraces"
40	depends on PRINTK
41	help
42	  Selecting this option adds build ID information for symbols in
43	  stacktraces printed with the printk format '%p[SR]b'.
44
45	  This option is intended for distros where debuginfo is not easily
46	  accessible but can be downloaded given the build ID of the vmlinux or
47	  kernel module where the function is located.
48
49config CONSOLE_LOGLEVEL_DEFAULT
50	int "Default console loglevel (1-15)"
51	range 1 15
52	default "7"
53	help
54	  Default loglevel to determine what will be printed on the console.
55
56	  Setting a default here is equivalent to passing in loglevel=<x> in
57	  the kernel bootargs. loglevel=<x> continues to override whatever
58	  value is specified here as well.
59
60	  Note: This does not affect the log level of un-prefixed printk()
61	  usage in the kernel. That is controlled by the MESSAGE_LOGLEVEL_DEFAULT
62	  option.
63
64config CONSOLE_LOGLEVEL_QUIET
65	int "quiet console loglevel (1-15)"
66	range 1 15
67	default "4"
68	help
69	  loglevel to use when "quiet" is passed on the kernel commandline.
70
71	  When "quiet" is passed on the kernel commandline this loglevel
72	  will be used as the loglevel. IOW passing "quiet" will be the
73	  equivalent of passing "loglevel=<CONSOLE_LOGLEVEL_QUIET>"
74
75config MESSAGE_LOGLEVEL_DEFAULT
76	int "Default message log level (1-7)"
77	range 1 7
78	default "4"
79	help
80	  Default log level for printk statements with no specified priority.
81
82	  This was hard-coded to KERN_WARNING since at least 2.6.10 but folks
83	  that are auditing their logs closely may want to set it to a lower
84	  priority.
85
86	  Note: This does not affect what message level gets printed on the console
87	  by default. To change that, use loglevel=<x> in the kernel bootargs,
88	  or pick a different CONSOLE_LOGLEVEL_DEFAULT configuration value.
89
90config BOOT_PRINTK_DELAY
91	bool "Delay each boot printk message by N milliseconds"
92	depends on DEBUG_KERNEL && PRINTK && GENERIC_CALIBRATE_DELAY
93	help
94	  This build option allows you to read kernel boot messages
95	  by inserting a short delay after each one.  The delay is
96	  specified in milliseconds on the kernel command line,
97	  using "boot_delay=N".
98
99	  It is likely that you would also need to use "lpj=M" to preset
100	  the "loops per jiffie" value.
101	  See a previous boot log for the "lpj" value to use for your
102	  system, and then set "lpj=M" before setting "boot_delay=N".
103	  NOTE:  Using this option may adversely affect SMP systems.
104	  I.e., processors other than the first one may not boot up.
105	  BOOT_PRINTK_DELAY also may cause LOCKUP_DETECTOR to detect
106	  what it believes to be lockup conditions.
107
108config DYNAMIC_DEBUG
109	bool "Enable dynamic printk() support"
110	default n
111	depends on PRINTK
112	depends on (DEBUG_FS || PROC_FS)
113	select DYNAMIC_DEBUG_CORE
114	help
115
116	  Compiles debug level messages into the kernel, which would not
117	  otherwise be available at runtime. These messages can then be
118	  enabled/disabled based on various levels of scope - per source file,
119	  function, module, format string, and line number. This mechanism
120	  implicitly compiles in all pr_debug() and dev_dbg() calls, which
121	  enlarges the kernel text size by about 2%.
122
123	  If a source file is compiled with DEBUG flag set, any
124	  pr_debug() calls in it are enabled by default, but can be
125	  disabled at runtime as below.  Note that DEBUG flag is
126	  turned on by many CONFIG_*DEBUG* options.
127
128	  Usage:
129
130	  Dynamic debugging is controlled via the 'dynamic_debug/control' file,
131	  which is contained in the 'debugfs' filesystem or procfs.
132	  Thus, the debugfs or procfs filesystem must first be mounted before
133	  making use of this feature.
134	  We refer the control file as: <debugfs>/dynamic_debug/control. This
135	  file contains a list of the debug statements that can be enabled. The
136	  format for each line of the file is:
137
138		filename:lineno [module]function flags format
139
140	  filename : source file of the debug statement
141	  lineno : line number of the debug statement
142	  module : module that contains the debug statement
143	  function : function that contains the debug statement
144	  flags : '=p' means the line is turned 'on' for printing
145	  format : the format used for the debug statement
146
147	  From a live system:
148
149		nullarbor:~ # cat <debugfs>/dynamic_debug/control
150		# filename:lineno [module]function flags format
151		fs/aio.c:222 [aio]__put_ioctx =_ "__put_ioctx:\040freeing\040%p\012"
152		fs/aio.c:248 [aio]ioctx_alloc =_ "ENOMEM:\040nr_events\040too\040high\012"
153		fs/aio.c:1770 [aio]sys_io_cancel =_ "calling\040cancel\012"
154
155	  Example usage:
156
157		// enable the message at line 1603 of file svcsock.c
158		nullarbor:~ # echo -n 'file svcsock.c line 1603 +p' >
159						<debugfs>/dynamic_debug/control
160
161		// enable all the messages in file svcsock.c
162		nullarbor:~ # echo -n 'file svcsock.c +p' >
163						<debugfs>/dynamic_debug/control
164
165		// enable all the messages in the NFS server module
166		nullarbor:~ # echo -n 'module nfsd +p' >
167						<debugfs>/dynamic_debug/control
168
169		// enable all 12 messages in the function svc_process()
170		nullarbor:~ # echo -n 'func svc_process +p' >
171						<debugfs>/dynamic_debug/control
172
173		// disable all 12 messages in the function svc_process()
174		nullarbor:~ # echo -n 'func svc_process -p' >
175						<debugfs>/dynamic_debug/control
176
177	  See Documentation/admin-guide/dynamic-debug-howto.rst for additional
178	  information.
179
180config DYNAMIC_DEBUG_CORE
181	bool "Enable core function of dynamic debug support"
182	depends on PRINTK
183	depends on (DEBUG_FS || PROC_FS)
184	help
185	  Enable core functional support of dynamic debug. It is useful
186	  when you want to tie dynamic debug to your kernel modules with
187	  DYNAMIC_DEBUG_MODULE defined for each of them, especially for
188	  the case of embedded system where the kernel image size is
189	  sensitive for people.
190
191config SYMBOLIC_ERRNAME
192	bool "Support symbolic error names in printf"
193	default y if PRINTK
194	help
195	  If you say Y here, the kernel's printf implementation will
196	  be able to print symbolic error names such as ENOSPC instead
197	  of the number 28. It makes the kernel image slightly larger
198	  (about 3KB), but can make the kernel logs easier to read.
199
200config DEBUG_BUGVERBOSE
201	bool "Verbose BUG() reporting (adds 70K)" if DEBUG_KERNEL && EXPERT
202	depends on BUG && (GENERIC_BUG || HAVE_DEBUG_BUGVERBOSE)
203	default y
204	help
205	  Say Y here to make BUG() panics output the file name and line number
206	  of the BUG call as well as the EIP and oops trace.  This aids
207	  debugging but costs about 70-100K of memory.
208
209endmenu # "printk and dmesg options"
210
211config DEBUG_KERNEL
212	bool "Kernel debugging"
213	help
214	  Say Y here if you are developing drivers or trying to debug and
215	  identify kernel problems.
216
217config DEBUG_MISC
218	bool "Miscellaneous debug code"
219	default DEBUG_KERNEL
220	depends on DEBUG_KERNEL
221	help
222	  Say Y here if you need to enable miscellaneous debug code that should
223	  be under a more specific debug option but isn't.
224
225menu "Compile-time checks and compiler options"
226
227config DEBUG_INFO
228	bool
229	help
230	  A kernel debug info option other than "None" has been selected
231	  in the "Debug information" choice below, indicating that debug
232	  information will be generated for build targets.
233
234# Clang is known to generate .{s,u}leb128 with symbol deltas with DWARF5, which
235# some targets may not support: https://sourceware.org/bugzilla/show_bug.cgi?id=27215
236config AS_HAS_NON_CONST_LEB128
237	def_bool $(as-instr,.uleb128 .Lexpr_end4 - .Lexpr_start3\n.Lexpr_start3:\n.Lexpr_end4:)
238
239choice
240	prompt "Debug information"
241	depends on DEBUG_KERNEL
242	help
243	  Selecting something other than "None" results in a kernel image
244	  that will include debugging info resulting in a larger kernel image.
245	  This adds debug symbols to the kernel and modules (gcc -g), and
246	  is needed if you intend to use kernel crashdump or binary object
247	  tools like crash, kgdb, LKCD, gdb, etc on the kernel.
248
249	  Choose which version of DWARF debug info to emit. If unsure,
250	  select "Toolchain default".
251
252config DEBUG_INFO_NONE
253	bool "Disable debug information"
254	help
255	  Do not build the kernel with debugging information, which will
256	  result in a faster and smaller build.
257
258config DEBUG_INFO_DWARF_TOOLCHAIN_DEFAULT
259	bool "Rely on the toolchain's implicit default DWARF version"
260	select DEBUG_INFO
261	depends on !CC_IS_CLANG || AS_IS_LLVM || CLANG_VERSION < 140000 || (AS_IS_GNU && AS_VERSION >= 23502 && AS_HAS_NON_CONST_LEB128)
262	help
263	  The implicit default version of DWARF debug info produced by a
264	  toolchain changes over time.
265
266	  This can break consumers of the debug info that haven't upgraded to
267	  support newer revisions, and prevent testing newer versions, but
268	  those should be less common scenarios.
269
270config DEBUG_INFO_DWARF4
271	bool "Generate DWARF Version 4 debuginfo"
272	select DEBUG_INFO
273	depends on !CC_IS_CLANG || AS_IS_LLVM || (AS_IS_GNU && AS_VERSION >= 23502)
274	help
275	  Generate DWARF v4 debug info. This requires gcc 4.5+, binutils 2.35.2
276	  if using clang without clang's integrated assembler, and gdb 7.0+.
277
278	  If you have consumers of DWARF debug info that are not ready for
279	  newer revisions of DWARF, you may wish to choose this or have your
280	  config select this.
281
282config DEBUG_INFO_DWARF5
283	bool "Generate DWARF Version 5 debuginfo"
284	select DEBUG_INFO
285	depends on !CC_IS_CLANG || AS_IS_LLVM || (AS_IS_GNU && AS_VERSION >= 23502 && AS_HAS_NON_CONST_LEB128)
286	help
287	  Generate DWARF v5 debug info. Requires binutils 2.35.2, gcc 5.0+ (gcc
288	  5.0+ accepts the -gdwarf-5 flag but only had partial support for some
289	  draft features until 7.0), and gdb 8.0+.
290
291	  Changes to the structure of debug info in Version 5 allow for around
292	  15-18% savings in resulting image and debug info section sizes as
293	  compared to DWARF Version 4. DWARF Version 5 standardizes previous
294	  extensions such as accelerators for symbol indexing and the format
295	  for fission (.dwo/.dwp) files. Users may not want to select this
296	  config if they rely on tooling that has not yet been updated to
297	  support DWARF Version 5.
298
299endchoice # "Debug information"
300
301if DEBUG_INFO
302
303config DEBUG_INFO_REDUCED
304	bool "Reduce debugging information"
305	help
306	  If you say Y here gcc is instructed to generate less debugging
307	  information for structure types. This means that tools that
308	  need full debugging information (like kgdb or systemtap) won't
309	  be happy. But if you merely need debugging information to
310	  resolve line numbers there is no loss. Advantage is that
311	  build directory object sizes shrink dramatically over a full
312	  DEBUG_INFO build and compile times are reduced too.
313	  Only works with newer gcc versions.
314
315choice
316	prompt "Compressed Debug information"
317	help
318	  Compress the resulting debug info. Results in smaller debug info sections,
319	  but requires that consumers are able to decompress the results.
320
321	  If unsure, choose DEBUG_INFO_COMPRESSED_NONE.
322
323config DEBUG_INFO_COMPRESSED_NONE
324	bool "Don't compress debug information"
325	help
326	  Don't compress debug info sections.
327
328config DEBUG_INFO_COMPRESSED_ZLIB
329	bool "Compress debugging information with zlib"
330	depends on $(cc-option,-gz=zlib)
331	depends on $(ld-option,--compress-debug-sections=zlib)
332	help
333	  Compress the debug information using zlib.  Requires GCC 5.0+ or Clang
334	  5.0+, binutils 2.26+, and zlib.
335
336	  Users of dpkg-deb via scripts/package/builddeb may find an increase in
337	  size of their debug .deb packages with this config set, due to the
338	  debug info being compressed with zlib, then the object files being
339	  recompressed with a different compression scheme. But this is still
340	  preferable to setting $KDEB_COMPRESS to "none" which would be even
341	  larger.
342
343config DEBUG_INFO_COMPRESSED_ZSTD
344	bool "Compress debugging information with zstd"
345	depends on $(cc-option,-gz=zstd)
346	depends on $(ld-option,--compress-debug-sections=zstd)
347	help
348	  Compress the debug information using zstd.  This may provide better
349	  compression than zlib, for about the same time costs, but requires newer
350	  toolchain support.  Requires GCC 13.0+ or Clang 16.0+, binutils 2.40+, and
351	  zstd.
352
353endchoice # "Compressed Debug information"
354
355config DEBUG_INFO_SPLIT
356	bool "Produce split debuginfo in .dwo files"
357	depends on $(cc-option,-gsplit-dwarf)
358	# RISC-V linker relaxation + -gsplit-dwarf has issues with LLVM and GCC
359	# prior to 12.x:
360	# https://github.com/llvm/llvm-project/issues/56642
361	# https://gcc.gnu.org/bugzilla/show_bug.cgi?id=99090
362	depends on !RISCV || GCC_VERSION >= 120000
363	help
364	  Generate debug info into separate .dwo files. This significantly
365	  reduces the build directory size for builds with DEBUG_INFO,
366	  because it stores the information only once on disk in .dwo
367	  files instead of multiple times in object files and executables.
368	  In addition the debug information is also compressed.
369
370	  Requires recent gcc (4.7+) and recent gdb/binutils.
371	  Any tool that packages or reads debug information would need
372	  to know about the .dwo files and include them.
373	  Incompatible with older versions of ccache.
374
375config DEBUG_INFO_BTF
376	bool "Generate BTF typeinfo"
377	depends on !DEBUG_INFO_SPLIT && !DEBUG_INFO_REDUCED
378	depends on !GCC_PLUGIN_RANDSTRUCT || COMPILE_TEST
379	depends on BPF_SYSCALL
380	depends on !DEBUG_INFO_DWARF5 || PAHOLE_VERSION >= 121
381	help
382	  Generate deduplicated BTF type information from DWARF debug info.
383	  Turning this on expects presence of pahole tool, which will convert
384	  DWARF type info into equivalent deduplicated BTF type info.
385
386config PAHOLE_HAS_SPLIT_BTF
387	def_bool PAHOLE_VERSION >= 119
388
389config PAHOLE_HAS_BTF_TAG
390	def_bool PAHOLE_VERSION >= 123
391	depends on CC_IS_CLANG
392	help
393	  Decide whether pahole emits btf_tag attributes (btf_type_tag and
394	  btf_decl_tag) or not. Currently only clang compiler implements
395	  these attributes, so make the config depend on CC_IS_CLANG.
396
397config PAHOLE_HAS_LANG_EXCLUDE
398	def_bool PAHOLE_VERSION >= 124
399	help
400	  Support for the --lang_exclude flag which makes pahole exclude
401	  compilation units from the supplied language. Used in Kbuild to
402	  omit Rust CUs which are not supported in version 1.24 of pahole,
403	  otherwise it would emit malformed kernel and module binaries when
404	  using DEBUG_INFO_BTF_MODULES.
405
406config DEBUG_INFO_BTF_MODULES
407	def_bool y
408	depends on DEBUG_INFO_BTF && MODULES && PAHOLE_HAS_SPLIT_BTF
409	help
410	  Generate compact split BTF type information for kernel modules.
411
412config MODULE_ALLOW_BTF_MISMATCH
413	bool "Allow loading modules with non-matching BTF type info"
414	depends on DEBUG_INFO_BTF_MODULES
415	help
416	  For modules whose split BTF does not match vmlinux, load without
417	  BTF rather than refusing to load. The default behavior with
418	  module BTF enabled is to reject modules with such mismatches;
419	  this option will still load module BTF where possible but ignore
420	  it when a mismatch is found.
421
422config GDB_SCRIPTS
423	bool "Provide GDB scripts for kernel debugging"
424	help
425	  This creates the required links to GDB helper scripts in the
426	  build directory. If you load vmlinux into gdb, the helper
427	  scripts will be automatically imported by gdb as well, and
428	  additional functions are available to analyze a Linux kernel
429	  instance. See Documentation/dev-tools/gdb-kernel-debugging.rst
430	  for further details.
431
432endif # DEBUG_INFO
433
434config FRAME_WARN
435	int "Warn for stack frames larger than"
436	range 0 8192
437	default 0 if KMSAN
438	default 2048 if GCC_PLUGIN_LATENT_ENTROPY
439	default 2048 if PARISC
440	default 1536 if (!64BIT && XTENSA)
441	default 1280 if KASAN && !64BIT
442	default 1024 if !64BIT
443	default 2048 if 64BIT
444	help
445	  Tell the compiler to warn at build time for stack frames larger than this.
446	  Setting this too low will cause a lot of warnings.
447	  Setting it to 0 disables the warning.
448
449config STRIP_ASM_SYMS
450	bool "Strip assembler-generated symbols during link"
451	default n
452	help
453	  Strip internal assembler-generated symbols during a link (symbols
454	  that look like '.Lxxx') so they don't pollute the output of
455	  get_wchan() and suchlike.
456
457config READABLE_ASM
458	bool "Generate readable assembler code"
459	depends on DEBUG_KERNEL
460	depends on CC_IS_GCC
461	help
462	  Disable some compiler optimizations that tend to generate human unreadable
463	  assembler output. This may make the kernel slightly slower, but it helps
464	  to keep kernel developers who have to stare a lot at assembler listings
465	  sane.
466
467config HEADERS_INSTALL
468	bool "Install uapi headers to usr/include"
469	depends on !UML
470	help
471	  This option will install uapi headers (headers exported to user-space)
472	  into the usr/include directory for use during the kernel build.
473	  This is unneeded for building the kernel itself, but needed for some
474	  user-space program samples. It is also needed by some features such
475	  as uapi header sanity checks.
476
477config DEBUG_SECTION_MISMATCH
478	bool "Enable full Section mismatch analysis"
479	depends on CC_IS_GCC
480	help
481	  The section mismatch analysis checks if there are illegal
482	  references from one section to another section.
483	  During linktime or runtime, some sections are dropped;
484	  any use of code/data previously in these sections would
485	  most likely result in an oops.
486	  In the code, functions and variables are annotated with
487	  __init,, etc. (see the full list in include/linux/init.h),
488	  which results in the code/data being placed in specific sections.
489	  The section mismatch analysis is always performed after a full
490	  kernel build, and enabling this option causes the following
491	  additional step to occur:
492	  - Add the option -fno-inline-functions-called-once to gcc commands.
493	    When inlining a function annotated with __init in a non-init
494	    function, we would lose the section information and thus
495	    the analysis would not catch the illegal reference.
496	    This option tells gcc to inline less (but it does result in
497	    a larger kernel).
498
499config SECTION_MISMATCH_WARN_ONLY
500	bool "Make section mismatch errors non-fatal"
501	default y
502	help
503	  If you say N here, the build process will fail if there are any
504	  section mismatch, instead of just throwing warnings.
505
506	  If unsure, say Y.
507
508config DEBUG_FORCE_FUNCTION_ALIGN_64B
509	bool "Force all function address 64B aligned"
510	depends on EXPERT && (X86_64 || ARM64 || PPC32 || PPC64 || ARC || RISCV || S390)
511	select FUNCTION_ALIGNMENT_64B
512	help
513	  There are cases that a commit from one domain changes the function
514	  address alignment of other domains, and cause magic performance
515	  bump (regression or improvement). Enable this option will help to
516	  verify if the bump is caused by function alignment changes, while
517	  it will slightly increase the kernel size and affect icache usage.
518
519	  It is mainly for debug and performance tuning use.
520
521#
522# Select this config option from the architecture Kconfig, if it
523# is preferred to always offer frame pointers as a config
524# option on the architecture (regardless of KERNEL_DEBUG):
525#
526config ARCH_WANT_FRAME_POINTERS
527	bool
528
529config FRAME_POINTER
530	bool "Compile the kernel with frame pointers"
531	depends on DEBUG_KERNEL && (M68K || UML || SUPERH) || ARCH_WANT_FRAME_POINTERS
532	default y if (DEBUG_INFO && UML) || ARCH_WANT_FRAME_POINTERS
533	help
534	  If you say Y here the resulting kernel image will be slightly
535	  larger and slower, but it gives very useful debugging information
536	  in case of kernel bugs. (precise oopses/stacktraces/warnings)
537
538config OBJTOOL
539	bool
540
541config STACK_VALIDATION
542	bool "Compile-time stack metadata validation"
543	depends on HAVE_STACK_VALIDATION && UNWINDER_FRAME_POINTER
544	select OBJTOOL
545	default n
546	help
547	  Validate frame pointer rules at compile-time.  This helps ensure that
548	  runtime stack traces are more reliable.
549
550	  For more information, see
551	  tools/objtool/Documentation/objtool.txt.
552
553config NOINSTR_VALIDATION
554	bool
555	depends on HAVE_NOINSTR_VALIDATION && DEBUG_ENTRY
556	select OBJTOOL
557	default y
558
559config VMLINUX_MAP
560	bool "Generate vmlinux.map file when linking"
561	depends on EXPERT
562	help
563	  Selecting this option will pass "-Map=vmlinux.map" to ld
564	  when linking vmlinux. That file can be useful for verifying
565	  and debugging magic section games, and for seeing which
566	  pieces of code get eliminated with
567	  CONFIG_LD_DEAD_CODE_DATA_ELIMINATION.
568
569config DEBUG_FORCE_WEAK_PER_CPU
570	bool "Force weak per-cpu definitions"
571	depends on DEBUG_KERNEL
572	help
573	  s390 and alpha require percpu variables in modules to be
574	  defined weak to work around addressing range issue which
575	  puts the following two restrictions on percpu variable
576	  definitions.
577
578	  1. percpu symbols must be unique whether static or not
579	  2. percpu variables can't be defined inside a function
580
581	  To ensure that generic code follows the above rules, this
582	  option forces all percpu variables to be defined as weak.
583
584endmenu # "Compiler options"
585
586menu "Generic Kernel Debugging Instruments"
587
588config MAGIC_SYSRQ
589	bool "Magic SysRq key"
590	depends on !UML
591	help
592	  If you say Y here, you will have some control over the system even
593	  if the system crashes for example during kernel debugging (e.g., you
594	  will be able to flush the buffer cache to disk, reboot the system
595	  immediately or dump some status information). This is accomplished
596	  by pressing various keys while holding SysRq (Alt+PrintScreen). It
597	  also works on a serial console (on PC hardware at least), if you
598	  send a BREAK and then within 5 seconds a command keypress. The
599	  keys are documented in <file:Documentation/admin-guide/sysrq.rst>.
600	  Don't say Y unless you really know what this hack does.
601
602config MAGIC_SYSRQ_DEFAULT_ENABLE
603	hex "Enable magic SysRq key functions by default"
604	depends on MAGIC_SYSRQ
605	default 0x1
606	help
607	  Specifies which SysRq key functions are enabled by default.
608	  This may be set to 1 or 0 to enable or disable them all, or
609	  to a bitmask as described in Documentation/admin-guide/sysrq.rst.
610
611config MAGIC_SYSRQ_SERIAL
612	bool "Enable magic SysRq key over serial"
613	depends on MAGIC_SYSRQ
614	default y
615	help
616	  Many embedded boards have a disconnected TTL level serial which can
617	  generate some garbage that can lead to spurious false sysrq detects.
618	  This option allows you to decide whether you want to enable the
619	  magic SysRq key.
620
621config MAGIC_SYSRQ_SERIAL_SEQUENCE
622	string "Char sequence that enables magic SysRq over serial"
623	depends on MAGIC_SYSRQ_SERIAL
624	default ""
625	help
626	  Specifies a sequence of characters that can follow BREAK to enable
627	  SysRq on a serial console.
628
629	  If unsure, leave an empty string and the option will not be enabled.
630
631config DEBUG_FS
632	bool "Debug Filesystem"
633	help
634	  debugfs is a virtual file system that kernel developers use to put
635	  debugging files into.  Enable this option to be able to read and
636	  write to these files.
637
638	  For detailed documentation on the debugfs API, see
639	  Documentation/filesystems/.
640
641	  If unsure, say N.
642
643choice
644	prompt "Debugfs default access"
645	depends on DEBUG_FS
646	default DEBUG_FS_ALLOW_ALL
647	help
648	  This selects the default access restrictions for debugfs.
649	  It can be overridden with kernel command line option
650	  debugfs=[on,no-mount,off]. The restrictions apply for API access
651	  and filesystem registration.
652
653config DEBUG_FS_ALLOW_ALL
654	bool "Access normal"
655	help
656	  No restrictions apply. Both API and filesystem registration
657	  is on. This is the normal default operation.
658
659config DEBUG_FS_DISALLOW_MOUNT
660	bool "Do not register debugfs as filesystem"
661	help
662	  The API is open but filesystem is not loaded. Clients can still do
663	  their work and read with debug tools that do not need
664	  debugfs filesystem.
665
666config DEBUG_FS_ALLOW_NONE
667	bool "No access"
668	help
669	  Access is off. Clients get -PERM when trying to create nodes in
670	  debugfs tree and debugfs is not registered as a filesystem.
671	  Client can then back-off or continue without debugfs access.
672
673endchoice
674
675source "lib/Kconfig.kgdb"
676source "lib/Kconfig.ubsan"
677source "lib/Kconfig.kcsan"
678
679endmenu
680
681menu "Networking Debugging"
682
683source "net/Kconfig.debug"
684
685endmenu # "Networking Debugging"
686
687menu "Memory Debugging"
688
689source "mm/Kconfig.debug"
690
691config DEBUG_OBJECTS
692	bool "Debug object operations"
693	depends on DEBUG_KERNEL
694	help
695	  If you say Y here, additional code will be inserted into the
696	  kernel to track the life time of various objects and validate
697	  the operations on those objects.
698
699config DEBUG_OBJECTS_SELFTEST
700	bool "Debug objects selftest"
701	depends on DEBUG_OBJECTS
702	help
703	  This enables the selftest of the object debug code.
704
705config DEBUG_OBJECTS_FREE
706	bool "Debug objects in freed memory"
707	depends on DEBUG_OBJECTS
708	help
709	  This enables checks whether a k/v free operation frees an area
710	  which contains an object which has not been deactivated
711	  properly. This can make kmalloc/kfree-intensive workloads
712	  much slower.
713
714config DEBUG_OBJECTS_TIMERS
715	bool "Debug timer objects"
716	depends on DEBUG_OBJECTS
717	help
718	  If you say Y here, additional code will be inserted into the
719	  timer routines to track the life time of timer objects and
720	  validate the timer operations.
721
722config DEBUG_OBJECTS_WORK
723	bool "Debug work objects"
724	depends on DEBUG_OBJECTS
725	help
726	  If you say Y here, additional code will be inserted into the
727	  work queue routines to track the life time of work objects and
728	  validate the work operations.
729
730config DEBUG_OBJECTS_RCU_HEAD
731	bool "Debug RCU callbacks objects"
732	depends on DEBUG_OBJECTS
733	help
734	  Enable this to turn on debugging of RCU list heads (call_rcu() usage).
735
736config DEBUG_OBJECTS_PERCPU_COUNTER
737	bool "Debug percpu counter objects"
738	depends on DEBUG_OBJECTS
739	help
740	  If you say Y here, additional code will be inserted into the
741	  percpu counter routines to track the life time of percpu counter
742	  objects and validate the percpu counter operations.
743
744config DEBUG_OBJECTS_ENABLE_DEFAULT
745	int "debug_objects bootup default value (0-1)"
746	range 0 1
747	default "1"
748	depends on DEBUG_OBJECTS
749	help
750	  Debug objects boot parameter default value
751
752config SHRINKER_DEBUG
753	bool "Enable shrinker debugging support"
754	depends on DEBUG_FS
755	help
756	  Say Y to enable the shrinker debugfs interface which provides
757	  visibility into the kernel memory shrinkers subsystem.
758	  Disable it to avoid an extra memory footprint.
759
760config DEBUG_STACK_USAGE
761	bool "Stack utilization instrumentation"
762	depends on DEBUG_KERNEL && !IA64
763	help
764	  Enables the display of the minimum amount of free stack which each
765	  task has ever had available in the sysrq-T and sysrq-P debug output.
766
767	  This option will slow down process creation somewhat.
768
769config SCHED_STACK_END_CHECK
770	bool "Detect stack corruption on calls to schedule()"
771	depends on DEBUG_KERNEL
772	default n
773	help
774	  This option checks for a stack overrun on calls to schedule().
775	  If the stack end location is found to be over written always panic as
776	  the content of the corrupted region can no longer be trusted.
777	  This is to ensure no erroneous behaviour occurs which could result in
778	  data corruption or a sporadic crash at a later stage once the region
779	  is examined. The runtime overhead introduced is minimal.
780
781config ARCH_HAS_DEBUG_VM_PGTABLE
782	bool
783	help
784	  An architecture should select this when it can successfully
785	  build and run DEBUG_VM_PGTABLE.
786
787config DEBUG_VM_IRQSOFF
788	def_bool DEBUG_VM && !PREEMPT_RT
789
790config DEBUG_VM
791	bool "Debug VM"
792	depends on DEBUG_KERNEL
793	help
794	  Enable this to turn on extended checks in the virtual-memory system
795	  that may impact performance.
796
797	  If unsure, say N.
798
799config DEBUG_VM_SHOOT_LAZIES
800	bool "Debug MMU_LAZY_TLB_SHOOTDOWN implementation"
801	depends on DEBUG_VM
802	depends on MMU_LAZY_TLB_SHOOTDOWN
803	help
804	  Enable additional IPIs that ensure lazy tlb mm references are removed
805	  before the mm is freed.
806
807	  If unsure, say N.
808
809config DEBUG_VM_MAPLE_TREE
810	bool "Debug VM maple trees"
811	depends on DEBUG_VM
812	select DEBUG_MAPLE_TREE
813	help
814	  Enable VM maple tree debugging information and extra validations.
815
816	  If unsure, say N.
817
818config DEBUG_VM_RB
819	bool "Debug VM red-black trees"
820	depends on DEBUG_VM
821	help
822	  Enable VM red-black tree debugging information and extra validations.
823
824	  If unsure, say N.
825
826config DEBUG_VM_PGFLAGS
827	bool "Debug page-flags operations"
828	depends on DEBUG_VM
829	help
830	  Enables extra validation on page flags operations.
831
832	  If unsure, say N.
833
834config DEBUG_VM_PGTABLE
835	bool "Debug arch page table for semantics compliance"
836	depends on MMU
837	depends on ARCH_HAS_DEBUG_VM_PGTABLE
838	default y if DEBUG_VM
839	help
840	  This option provides a debug method which can be used to test
841	  architecture page table helper functions on various platforms in
842	  verifying if they comply with expected generic MM semantics. This
843	  will help architecture code in making sure that any changes or
844	  new additions of these helpers still conform to expected
845	  semantics of the generic MM. Platforms will have to opt in for
846	  this through ARCH_HAS_DEBUG_VM_PGTABLE.
847
848	  If unsure, say N.
849
850config ARCH_HAS_DEBUG_VIRTUAL
851	bool
852
853config DEBUG_VIRTUAL
854	bool "Debug VM translations"
855	depends on DEBUG_KERNEL && ARCH_HAS_DEBUG_VIRTUAL
856	help
857	  Enable some costly sanity checks in virtual to page code. This can
858	  catch mistakes with virt_to_page() and friends.
859
860	  If unsure, say N.
861
862config DEBUG_NOMMU_REGIONS
863	bool "Debug the global anon/private NOMMU mapping region tree"
864	depends on DEBUG_KERNEL && !MMU
865	help
866	  This option causes the global tree of anonymous and private mapping
867	  regions to be regularly checked for invalid topology.
868
869config DEBUG_MEMORY_INIT
870	bool "Debug memory initialisation" if EXPERT
871	default !EXPERT
872	help
873	  Enable this for additional checks during memory initialisation.
874	  The sanity checks verify aspects of the VM such as the memory model
875	  and other information provided by the architecture. Verbose
876	  information will be printed at KERN_DEBUG loglevel depending
877	  on the mminit_loglevel= command-line option.
878
879	  If unsure, say Y
880
881config MEMORY_NOTIFIER_ERROR_INJECT
882	tristate "Memory hotplug notifier error injection module"
883	depends on MEMORY_HOTPLUG && NOTIFIER_ERROR_INJECTION
884	help
885	  This option provides the ability to inject artificial errors to
886	  memory hotplug notifier chain callbacks.  It is controlled through
887	  debugfs interface under /sys/kernel/debug/notifier-error-inject/memory
888
889	  If the notifier call chain should be failed with some events
890	  notified, write the error code to "actions/<notifier event>/error".
891
892	  Example: Inject memory hotplug offline error (-12 == -ENOMEM)
893
894	  # cd /sys/kernel/debug/notifier-error-inject/memory
895	  # echo -12 > actions/MEM_GOING_OFFLINE/error
896	  # echo offline > /sys/devices/system/memory/memoryXXX/state
897	  bash: echo: write error: Cannot allocate memory
898
899	  To compile this code as a module, choose M here: the module will
900	  be called memory-notifier-error-inject.
901
902	  If unsure, say N.
903
904config DEBUG_PER_CPU_MAPS
905	bool "Debug access to per_cpu maps"
906	depends on DEBUG_KERNEL
907	depends on SMP
908	help
909	  Say Y to verify that the per_cpu map being accessed has
910	  been set up. This adds a fair amount of code to kernel memory
911	  and decreases performance.
912
913	  Say N if unsure.
914
915config DEBUG_KMAP_LOCAL
916	bool "Debug kmap_local temporary mappings"
917	depends on DEBUG_KERNEL && KMAP_LOCAL
918	help
919	  This option enables additional error checking for the kmap_local
920	  infrastructure.  Disable for production use.
921
922config ARCH_SUPPORTS_KMAP_LOCAL_FORCE_MAP
923	bool
924
925config DEBUG_KMAP_LOCAL_FORCE_MAP
926	bool "Enforce kmap_local temporary mappings"
927	depends on DEBUG_KERNEL && ARCH_SUPPORTS_KMAP_LOCAL_FORCE_MAP
928	select KMAP_LOCAL
929	select DEBUG_KMAP_LOCAL
930	help
931	  This option enforces temporary mappings through the kmap_local
932	  mechanism for non-highmem pages and on non-highmem systems.
933	  Disable this for production systems!
934
935config DEBUG_HIGHMEM
936	bool "Highmem debugging"
937	depends on DEBUG_KERNEL && HIGHMEM
938	select DEBUG_KMAP_LOCAL_FORCE_MAP if ARCH_SUPPORTS_KMAP_LOCAL_FORCE_MAP
939	select DEBUG_KMAP_LOCAL
940	help
941	  This option enables additional error checking for high memory
942	  systems.  Disable for production systems.
943
944config HAVE_DEBUG_STACKOVERFLOW
945	bool
946
947config DEBUG_STACKOVERFLOW
948	bool "Check for stack overflows"
949	depends on DEBUG_KERNEL && HAVE_DEBUG_STACKOVERFLOW
950	help
951	  Say Y here if you want to check for overflows of kernel, IRQ
952	  and exception stacks (if your architecture uses them). This
953	  option will show detailed messages if free stack space drops
954	  below a certain limit.
955
956	  These kinds of bugs usually occur when call-chains in the
957	  kernel get too deep, especially when interrupts are
958	  involved.
959
960	  Use this in cases where you see apparently random memory
961	  corruption, especially if it appears in 'struct thread_info'
962
963	  If in doubt, say "N".
964
965source "lib/Kconfig.kasan"
966source "lib/Kconfig.kfence"
967source "lib/Kconfig.kmsan"
968
969endmenu # "Memory Debugging"
970
971config DEBUG_SHIRQ
972	bool "Debug shared IRQ handlers"
973	depends on DEBUG_KERNEL
974	help
975	  Enable this to generate a spurious interrupt just before a shared
976	  interrupt handler is deregistered (generating one when registering
977	  is currently disabled). Drivers need to handle this correctly. Some
978	  don't and need to be caught.
979
980menu "Debug Oops, Lockups and Hangs"
981
982config PANIC_ON_OOPS
983	bool "Panic on Oops"
984	help
985	  Say Y here to enable the kernel to panic when it oopses. This
986	  has the same effect as setting oops=panic on the kernel command
987	  line.
988
989	  This feature is useful to ensure that the kernel does not do
990	  anything erroneous after an oops which could result in data
991	  corruption or other issues.
992
993	  Say N if unsure.
994
995config PANIC_ON_OOPS_VALUE
996	int
997	range 0 1
998	default 0 if !PANIC_ON_OOPS
999	default 1 if PANIC_ON_OOPS
1000
1001config PANIC_TIMEOUT
1002	int "panic timeout"
1003	default 0
1004	help
1005	  Set the timeout value (in seconds) until a reboot occurs when
1006	  the kernel panics. If n = 0, then we wait forever. A timeout
1007	  value n > 0 will wait n seconds before rebooting, while a timeout
1008	  value n < 0 will reboot immediately.
1009
1010config LOCKUP_DETECTOR
1011	bool
1012
1013config SOFTLOCKUP_DETECTOR
1014	bool "Detect Soft Lockups"
1015	depends on DEBUG_KERNEL && !S390
1016	select LOCKUP_DETECTOR
1017	help
1018	  Say Y here to enable the kernel to act as a watchdog to detect
1019	  soft lockups.
1020
1021	  Softlockups are bugs that cause the kernel to loop in kernel
1022	  mode for more than 20 seconds, without giving other tasks a
1023	  chance to run.  The current stack trace is displayed upon
1024	  detection and the system will stay locked up.
1025
1026config BOOTPARAM_SOFTLOCKUP_PANIC
1027	bool "Panic (Reboot) On Soft Lockups"
1028	depends on SOFTLOCKUP_DETECTOR
1029	help
1030	  Say Y here to enable the kernel to panic on "soft lockups",
1031	  which are bugs that cause the kernel to loop in kernel
1032	  mode for more than 20 seconds (configurable using the watchdog_thresh
1033	  sysctl), without giving other tasks a chance to run.
1034
1035	  The panic can be used in combination with panic_timeout,
1036	  to cause the system to reboot automatically after a
1037	  lockup has been detected. This feature is useful for
1038	  high-availability systems that have uptime guarantees and
1039	  where a lockup must be resolved ASAP.
1040
1041	  Say N if unsure.
1042
1043config HAVE_HARDLOCKUP_DETECTOR_BUDDY
1044	bool
1045	depends on SMP
1046	default y
1047
1048#
1049# Global switch whether to build a hardlockup detector at all. It is available
1050# only when the architecture supports at least one implementation. There are
1051# two exceptions. The hardlockup detector is never enabled on:
1052#
1053#	s390: it reported many false positives there
1054#
1055#	sparc64: has a custom implementation which is not using the common
1056#		hardlockup command line options and sysctl interface.
1057#
1058config HARDLOCKUP_DETECTOR
1059	bool "Detect Hard Lockups"
1060	depends on DEBUG_KERNEL && !S390 && !HARDLOCKUP_DETECTOR_SPARC64
1061	depends on HAVE_HARDLOCKUP_DETECTOR_PERF || HAVE_HARDLOCKUP_DETECTOR_BUDDY || HAVE_HARDLOCKUP_DETECTOR_ARCH
1062	imply HARDLOCKUP_DETECTOR_PERF
1063	imply HARDLOCKUP_DETECTOR_BUDDY
1064	imply HARDLOCKUP_DETECTOR_ARCH
1065	select LOCKUP_DETECTOR
1066
1067	help
1068	  Say Y here to enable the kernel to act as a watchdog to detect
1069	  hard lockups.
1070
1071	  Hardlockups are bugs that cause the CPU to loop in kernel mode
1072	  for more than 10 seconds, without letting other interrupts have a
1073	  chance to run.  The current stack trace is displayed upon detection
1074	  and the system will stay locked up.
1075
1076#
1077# Note that arch-specific variants are always preferred.
1078#
1079config HARDLOCKUP_DETECTOR_PREFER_BUDDY
1080	bool "Prefer the buddy CPU hardlockup detector"
1081	depends on HARDLOCKUP_DETECTOR
1082	depends on HAVE_HARDLOCKUP_DETECTOR_PERF && HAVE_HARDLOCKUP_DETECTOR_BUDDY
1083	depends on !HAVE_HARDLOCKUP_DETECTOR_ARCH
1084	help
1085	  Say Y here to prefer the buddy hardlockup detector over the perf one.
1086
1087	  With the buddy detector, each CPU uses its softlockup hrtimer
1088	  to check that the next CPU is processing hrtimer interrupts by
1089	  verifying that a counter is increasing.
1090
1091	  This hardlockup detector is useful on systems that don't have
1092	  an arch-specific hardlockup detector or if resources needed
1093	  for the hardlockup detector are better used for other things.
1094
1095config HARDLOCKUP_DETECTOR_PERF
1096	bool
1097	depends on HARDLOCKUP_DETECTOR
1098	depends on HAVE_HARDLOCKUP_DETECTOR_PERF && !HARDLOCKUP_DETECTOR_PREFER_BUDDY
1099	depends on !HAVE_HARDLOCKUP_DETECTOR_ARCH
1100	select HARDLOCKUP_DETECTOR_COUNTS_HRTIMER
1101
1102config HARDLOCKUP_DETECTOR_BUDDY
1103	bool
1104	depends on HARDLOCKUP_DETECTOR
1105	depends on HAVE_HARDLOCKUP_DETECTOR_BUDDY
1106	depends on !HAVE_HARDLOCKUP_DETECTOR_PERF || HARDLOCKUP_DETECTOR_PREFER_BUDDY
1107	depends on !HAVE_HARDLOCKUP_DETECTOR_ARCH
1108	select HARDLOCKUP_DETECTOR_COUNTS_HRTIMER
1109
1110config HARDLOCKUP_DETECTOR_ARCH
1111	bool
1112	depends on HARDLOCKUP_DETECTOR
1113	depends on HAVE_HARDLOCKUP_DETECTOR_ARCH
1114	help
1115	  The arch-specific implementation of the hardlockup detector will
1116	  be used.
1117
1118#
1119# Both the "perf" and "buddy" hardlockup detectors count hrtimer
1120# interrupts. This config enables functions managing this common code.
1121#
1122config HARDLOCKUP_DETECTOR_COUNTS_HRTIMER
1123	bool
1124	select SOFTLOCKUP_DETECTOR
1125
1126#
1127# Enables a timestamp based low pass filter to compensate for perf based
1128# hard lockup detection which runs too fast due to turbo modes.
1129#
1130config HARDLOCKUP_CHECK_TIMESTAMP
1131	bool
1132
1133config BOOTPARAM_HARDLOCKUP_PANIC
1134	bool "Panic (Reboot) On Hard Lockups"
1135	depends on HARDLOCKUP_DETECTOR
1136	help
1137	  Say Y here to enable the kernel to panic on "hard lockups",
1138	  which are bugs that cause the kernel to loop in kernel
1139	  mode with interrupts disabled for more than 10 seconds (configurable
1140	  using the watchdog_thresh sysctl).
1141
1142	  Say N if unsure.
1143
1144config DETECT_HUNG_TASK
1145	bool "Detect Hung Tasks"
1146	depends on DEBUG_KERNEL
1147	default SOFTLOCKUP_DETECTOR
1148	help
1149	  Say Y here to enable the kernel to detect "hung tasks",
1150	  which are bugs that cause the task to be stuck in
1151	  uninterruptible "D" state indefinitely.
1152
1153	  When a hung task is detected, the kernel will print the
1154	  current stack trace (which you should report), but the
1155	  task will stay in uninterruptible state. If lockdep is
1156	  enabled then all held locks will also be reported. This
1157	  feature has negligible overhead.
1158
1159config DEFAULT_HUNG_TASK_TIMEOUT
1160	int "Default timeout for hung task detection (in seconds)"
1161	depends on DETECT_HUNG_TASK
1162	default 120
1163	help
1164	  This option controls the default timeout (in seconds) used
1165	  to determine when a task has become non-responsive and should
1166	  be considered hung.
1167
1168	  It can be adjusted at runtime via the kernel.hung_task_timeout_secs
1169	  sysctl or by writing a value to
1170	  /proc/sys/kernel/hung_task_timeout_secs.
1171
1172	  A timeout of 0 disables the check.  The default is two minutes.
1173	  Keeping the default should be fine in most cases.
1174
1175config BOOTPARAM_HUNG_TASK_PANIC
1176	bool "Panic (Reboot) On Hung Tasks"
1177	depends on DETECT_HUNG_TASK
1178	help
1179	  Say Y here to enable the kernel to panic on "hung tasks",
1180	  which are bugs that cause the kernel to leave a task stuck
1181	  in uninterruptible "D" state.
1182
1183	  The panic can be used in combination with panic_timeout,
1184	  to cause the system to reboot automatically after a
1185	  hung task has been detected. This feature is useful for
1186	  high-availability systems that have uptime guarantees and
1187	  where a hung tasks must be resolved ASAP.
1188
1189	  Say N if unsure.
1190
1191config BOOTPARAM_HUNG_TASK_PANIC_VALUE
1192	int
1193	depends on DETECT_HUNG_TASK
1194	range 0 1
1195	default 0 if !BOOTPARAM_HUNG_TASK_PANIC
1196	default 1 if BOOTPARAM_HUNG_TASK_PANIC
1197
1198config WQ_WATCHDOG
1199	bool "Detect Workqueue Stalls"
1200	depends on DEBUG_KERNEL
1201	help
1202	  Say Y here to enable stall detection on workqueues.  If a
1203	  worker pool doesn't make forward progress on a pending work
1204	  item for over a given amount of time, 30s by default, a
1205	  warning message is printed along with dump of workqueue
1206	  state.  This can be configured through kernel parameter
1207	  "workqueue.watchdog_thresh" and its sysfs counterpart.
1208
1209config WQ_CPU_INTENSIVE_REPORT
1210	bool "Report per-cpu work items which hog CPU for too long"
1211	depends on DEBUG_KERNEL
1212	help
1213	  Say Y here to enable reporting of concurrency-managed per-cpu work
1214	  items that hog CPUs for longer than
1215	  workqueue.cpu_intensive_thresh_us. Workqueue automatically
1216	  detects and excludes them from concurrency management to prevent
1217	  them from stalling other per-cpu work items. Occassional
1218	  triggering may not necessarily indicate a problem. Repeated
1219	  triggering likely indicates that the work item should be switched
1220	  to use an unbound workqueue.
1221
1222config TEST_LOCKUP
1223	tristate "Test module to generate lockups"
1224	depends on m
1225	help
1226	  This builds the "test_lockup" module that helps to make sure
1227	  that watchdogs and lockup detectors are working properly.
1228
1229	  Depending on module parameters it could emulate soft or hard
1230	  lockup, "hung task", or locking arbitrary lock for a long time.
1231	  Also it could generate series of lockups with cooling-down periods.
1232
1233	  If unsure, say N.
1234
1235endmenu # "Debug lockups and hangs"
1236
1237menu "Scheduler Debugging"
1238
1239config SCHED_DEBUG
1240	bool "Collect scheduler debugging info"
1241	depends on DEBUG_KERNEL && DEBUG_FS
1242	default y
1243	help
1244	  If you say Y here, the /sys/kernel/debug/sched file will be provided
1245	  that can help debug the scheduler. The runtime overhead of this
1246	  option is minimal.
1247
1248config SCHED_INFO
1249	bool
1250	default n
1251
1252config SCHEDSTATS
1253	bool "Collect scheduler statistics"
1254	depends on DEBUG_KERNEL && PROC_FS
1255	select SCHED_INFO
1256	help
1257	  If you say Y here, additional code will be inserted into the
1258	  scheduler and related routines to collect statistics about
1259	  scheduler behavior and provide them in /proc/schedstat.  These
1260	  stats may be useful for both tuning and debugging the scheduler
1261	  If you aren't debugging the scheduler or trying to tune a specific
1262	  application, you can say N to avoid the very slight overhead
1263	  this adds.
1264
1265endmenu
1266
1267config DEBUG_TIMEKEEPING
1268	bool "Enable extra timekeeping sanity checking"
1269	help
1270	  This option will enable additional timekeeping sanity checks
1271	  which may be helpful when diagnosing issues where timekeeping
1272	  problems are suspected.
1273
1274	  This may include checks in the timekeeping hotpaths, so this
1275	  option may have a (very small) performance impact to some
1276	  workloads.
1277
1278	  If unsure, say N.
1279
1280config DEBUG_PREEMPT
1281	bool "Debug preemptible kernel"
1282	depends on DEBUG_KERNEL && PREEMPTION && TRACE_IRQFLAGS_SUPPORT
1283	help
1284	  If you say Y here then the kernel will use a debug variant of the
1285	  commonly used smp_processor_id() function and will print warnings
1286	  if kernel code uses it in a preemption-unsafe way. Also, the kernel
1287	  will detect preemption count underflows.
1288
1289	  This option has potential to introduce high runtime overhead,
1290	  depending on workload as it triggers debugging routines for each
1291	  this_cpu operation. It should only be used for debugging purposes.
1292
1293menu "Lock Debugging (spinlocks, mutexes, etc...)"
1294
1295config LOCK_DEBUGGING_SUPPORT
1296	bool
1297	depends on TRACE_IRQFLAGS_SUPPORT && STACKTRACE_SUPPORT && LOCKDEP_SUPPORT
1298	default y
1299
1300config PROVE_LOCKING
1301	bool "Lock debugging: prove locking correctness"
1302	depends on DEBUG_KERNEL && LOCK_DEBUGGING_SUPPORT
1303	select LOCKDEP
1304	select DEBUG_SPINLOCK
1305	select DEBUG_MUTEXES if !PREEMPT_RT
1306	select DEBUG_RT_MUTEXES if RT_MUTEXES
1307	select DEBUG_RWSEMS
1308	select DEBUG_WW_MUTEX_SLOWPATH
1309	select DEBUG_LOCK_ALLOC
1310	select PREEMPT_COUNT if !ARCH_NO_PREEMPT
1311	select TRACE_IRQFLAGS
1312	default n
1313	help
1314	 This feature enables the kernel to prove that all locking
1315	 that occurs in the kernel runtime is mathematically
1316	 correct: that under no circumstance could an arbitrary (and
1317	 not yet triggered) combination of observed locking
1318	 sequences (on an arbitrary number of CPUs, running an
1319	 arbitrary number of tasks and interrupt contexts) cause a
1320	 deadlock.
1321
1322	 In short, this feature enables the kernel to report locking
1323	 related deadlocks before they actually occur.
1324
1325	 The proof does not depend on how hard and complex a
1326	 deadlock scenario would be to trigger: how many
1327	 participant CPUs, tasks and irq-contexts would be needed
1328	 for it to trigger. The proof also does not depend on
1329	 timing: if a race and a resulting deadlock is possible
1330	 theoretically (no matter how unlikely the race scenario
1331	 is), it will be proven so and will immediately be
1332	 reported by the kernel (once the event is observed that
1333	 makes the deadlock theoretically possible).
1334
1335	 If a deadlock is impossible (i.e. the locking rules, as
1336	 observed by the kernel, are mathematically correct), the
1337	 kernel reports nothing.
1338
1339	 NOTE: this feature can also be enabled for rwlocks, mutexes
1340	 and rwsems - in which case all dependencies between these
1341	 different locking variants are observed and mapped too, and
1342	 the proof of observed correctness is also maintained for an
1343	 arbitrary combination of these separate locking variants.
1344
1345	 For more details, see Documentation/locking/lockdep-design.rst.
1346
1347config PROVE_RAW_LOCK_NESTING
1348	bool "Enable raw_spinlock - spinlock nesting checks"
1349	depends on PROVE_LOCKING
1350	default n
1351	help
1352	 Enable the raw_spinlock vs. spinlock nesting checks which ensure
1353	 that the lock nesting rules for PREEMPT_RT enabled kernels are
1354	 not violated.
1355
1356	 NOTE: There are known nesting problems. So if you enable this
1357	 option expect lockdep splats until these problems have been fully
1358	 addressed which is work in progress. This config switch allows to
1359	 identify and analyze these problems. It will be removed and the
1360	 check permanently enabled once the main issues have been fixed.
1361
1362	 If unsure, select N.
1363
1364config LOCK_STAT
1365	bool "Lock usage statistics"
1366	depends on DEBUG_KERNEL && LOCK_DEBUGGING_SUPPORT
1367	select LOCKDEP
1368	select DEBUG_SPINLOCK
1369	select DEBUG_MUTEXES if !PREEMPT_RT
1370	select DEBUG_RT_MUTEXES if RT_MUTEXES
1371	select DEBUG_LOCK_ALLOC
1372	default n
1373	help
1374	 This feature enables tracking lock contention points
1375
1376	 For more details, see Documentation/locking/lockstat.rst
1377
1378	 This also enables lock events required by "perf lock",
1379	 subcommand of perf.
1380	 If you want to use "perf lock", you also need to turn on
1381	 CONFIG_EVENT_TRACING.
1382
1383	 CONFIG_LOCK_STAT defines "contended" and "acquired" lock events.
1384	 (CONFIG_LOCKDEP defines "acquire" and "release" events.)
1385
1386config DEBUG_RT_MUTEXES
1387	bool "RT Mutex debugging, deadlock detection"
1388	depends on DEBUG_KERNEL && RT_MUTEXES
1389	help
1390	 This allows rt mutex semantics violations and rt mutex related
1391	 deadlocks (lockups) to be detected and reported automatically.
1392
1393config DEBUG_SPINLOCK
1394	bool "Spinlock and rw-lock debugging: basic checks"
1395	depends on DEBUG_KERNEL
1396	select UNINLINE_SPIN_UNLOCK
1397	help
1398	  Say Y here and build SMP to catch missing spinlock initialization
1399	  and certain other kinds of spinlock errors commonly made.  This is
1400	  best used in conjunction with the NMI watchdog so that spinlock
1401	  deadlocks are also debuggable.
1402
1403config DEBUG_MUTEXES
1404	bool "Mutex debugging: basic checks"
1405	depends on DEBUG_KERNEL && !PREEMPT_RT
1406	help
1407	 This feature allows mutex semantics violations to be detected and
1408	 reported.
1409
1410config DEBUG_WW_MUTEX_SLOWPATH
1411	bool "Wait/wound mutex debugging: Slowpath testing"
1412	depends on DEBUG_KERNEL && LOCK_DEBUGGING_SUPPORT
1413	select DEBUG_LOCK_ALLOC
1414	select DEBUG_SPINLOCK
1415	select DEBUG_MUTEXES if !PREEMPT_RT
1416	select DEBUG_RT_MUTEXES if PREEMPT_RT
1417	help
1418	 This feature enables slowpath testing for w/w mutex users by
1419	 injecting additional -EDEADLK wound/backoff cases. Together with
1420	 the full mutex checks enabled with (CONFIG_PROVE_LOCKING) this
1421	 will test all possible w/w mutex interface abuse with the
1422	 exception of simply not acquiring all the required locks.
1423	 Note that this feature can introduce significant overhead, so
1424	 it really should not be enabled in a production or distro kernel,
1425	 even a debug kernel.  If you are a driver writer, enable it.  If
1426	 you are a distro, do not.
1427
1428config DEBUG_RWSEMS
1429	bool "RW Semaphore debugging: basic checks"
1430	depends on DEBUG_KERNEL
1431	help
1432	  This debugging feature allows mismatched rw semaphore locks
1433	  and unlocks to be detected and reported.
1434
1435config DEBUG_LOCK_ALLOC
1436	bool "Lock debugging: detect incorrect freeing of live locks"
1437	depends on DEBUG_KERNEL && LOCK_DEBUGGING_SUPPORT
1438	select DEBUG_SPINLOCK
1439	select DEBUG_MUTEXES if !PREEMPT_RT
1440	select DEBUG_RT_MUTEXES if RT_MUTEXES
1441	select LOCKDEP
1442	help
1443	 This feature will check whether any held lock (spinlock, rwlock,
1444	 mutex or rwsem) is incorrectly freed by the kernel, via any of the
1445	 memory-freeing routines (kfree(), kmem_cache_free(), free_pages(),
1446	 vfree(), etc.), whether a live lock is incorrectly reinitialized via
1447	 spin_lock_init()/mutex_init()/etc., or whether there is any lock
1448	 held during task exit.
1449
1450config LOCKDEP
1451	bool
1452	depends on DEBUG_KERNEL && LOCK_DEBUGGING_SUPPORT
1453	select STACKTRACE
1454	select KALLSYMS
1455	select KALLSYMS_ALL
1456
1457config LOCKDEP_SMALL
1458	bool
1459
1460config LOCKDEP_BITS
1461	int "Bitsize for MAX_LOCKDEP_ENTRIES"
1462	depends on LOCKDEP && !LOCKDEP_SMALL
1463	range 10 30
1464	default 15
1465	help
1466	  Try increasing this value if you hit "BUG: MAX_LOCKDEP_ENTRIES too low!" message.
1467
1468config LOCKDEP_CHAINS_BITS
1469	int "Bitsize for MAX_LOCKDEP_CHAINS"
1470	depends on LOCKDEP && !LOCKDEP_SMALL
1471	range 10 30
1472	default 16
1473	help
1474	  Try increasing this value if you hit "BUG: MAX_LOCKDEP_CHAINS too low!" message.
1475
1476config LOCKDEP_STACK_TRACE_BITS
1477	int "Bitsize for MAX_STACK_TRACE_ENTRIES"
1478	depends on LOCKDEP && !LOCKDEP_SMALL
1479	range 10 30
1480	default 19
1481	help
1482	  Try increasing this value if you hit "BUG: MAX_STACK_TRACE_ENTRIES too low!" message.
1483
1484config LOCKDEP_STACK_TRACE_HASH_BITS
1485	int "Bitsize for STACK_TRACE_HASH_SIZE"
1486	depends on LOCKDEP && !LOCKDEP_SMALL
1487	range 10 30
1488	default 14
1489	help
1490	  Try increasing this value if you need large STACK_TRACE_HASH_SIZE.
1491
1492config LOCKDEP_CIRCULAR_QUEUE_BITS
1493	int "Bitsize for elements in circular_queue struct"
1494	depends on LOCKDEP
1495	range 10 30
1496	default 12
1497	help
1498	  Try increasing this value if you hit "lockdep bfs error:-1" warning due to __cq_enqueue() failure.
1499
1500config DEBUG_LOCKDEP
1501	bool "Lock dependency engine debugging"
1502	depends on DEBUG_KERNEL && LOCKDEP
1503	select DEBUG_IRQFLAGS
1504	help
1505	  If you say Y here, the lock dependency engine will do
1506	  additional runtime checks to debug itself, at the price
1507	  of more runtime overhead.
1508
1509config DEBUG_ATOMIC_SLEEP
1510	bool "Sleep inside atomic section checking"
1511	select PREEMPT_COUNT
1512	depends on DEBUG_KERNEL
1513	depends on !ARCH_NO_PREEMPT
1514	help
1515	  If you say Y here, various routines which may sleep will become very
1516	  noisy if they are called inside atomic sections: when a spinlock is
1517	  held, inside an rcu read side critical section, inside preempt disabled
1518	  sections, inside an interrupt, etc...
1519
1520config DEBUG_LOCKING_API_SELFTESTS
1521	bool "Locking API boot-time self-tests"
1522	depends on DEBUG_KERNEL
1523	help
1524	  Say Y here if you want the kernel to run a short self-test during
1525	  bootup. The self-test checks whether common types of locking bugs
1526	  are detected by debugging mechanisms or not. (if you disable
1527	  lock debugging then those bugs won't be detected of course.)
1528	  The following locking APIs are covered: spinlocks, rwlocks,
1529	  mutexes and rwsems.
1530
1531config LOCK_TORTURE_TEST
1532	tristate "torture tests for locking"
1533	depends on DEBUG_KERNEL
1534	select TORTURE_TEST
1535	help
1536	  This option provides a kernel module that runs torture tests
1537	  on kernel locking primitives.  The kernel module may be built
1538	  after the fact on the running kernel to be tested, if desired.
1539
1540	  Say Y here if you want kernel locking-primitive torture tests
1541	  to be built into the kernel.
1542	  Say M if you want these torture tests to build as a module.
1543	  Say N if you are unsure.
1544
1545config WW_MUTEX_SELFTEST
1546	tristate "Wait/wound mutex selftests"
1547	help
1548	  This option provides a kernel module that runs tests on the
1549	  on the struct ww_mutex locking API.
1550
1551	  It is recommended to enable DEBUG_WW_MUTEX_SLOWPATH in conjunction
1552	  with this test harness.
1553
1554	  Say M if you want these self tests to build as a module.
1555	  Say N if you are unsure.
1556
1557config SCF_TORTURE_TEST
1558	tristate "torture tests for smp_call_function*()"
1559	depends on DEBUG_KERNEL
1560	select TORTURE_TEST
1561	help
1562	  This option provides a kernel module that runs torture tests
1563	  on the smp_call_function() family of primitives.  The kernel
1564	  module may be built after the fact on the running kernel to
1565	  be tested, if desired.
1566
1567config CSD_LOCK_WAIT_DEBUG
1568	bool "Debugging for csd_lock_wait(), called from smp_call_function*()"
1569	depends on DEBUG_KERNEL
1570	depends on 64BIT
1571	default n
1572	help
1573	  This option enables debug prints when CPUs are slow to respond
1574	  to the smp_call_function*() IPI wrappers.  These debug prints
1575	  include the IPI handler function currently executing (if any)
1576	  and relevant stack traces.
1577
1578config CSD_LOCK_WAIT_DEBUG_DEFAULT
1579	bool "Default csd_lock_wait() debugging on at boot time"
1580	depends on CSD_LOCK_WAIT_DEBUG
1581	depends on 64BIT
1582	default n
1583	help
1584	  This option causes the csdlock_debug= kernel boot parameter to
1585	  default to 1 (basic debugging) instead of 0 (no debugging).
1586
1587endmenu # lock debugging
1588
1589config TRACE_IRQFLAGS
1590	depends on TRACE_IRQFLAGS_SUPPORT
1591	bool
1592	help
1593	  Enables hooks to interrupt enabling and disabling for
1594	  either tracing or lock debugging.
1595
1596config TRACE_IRQFLAGS_NMI
1597	def_bool y
1598	depends on TRACE_IRQFLAGS
1599	depends on TRACE_IRQFLAGS_NMI_SUPPORT
1600
1601config NMI_CHECK_CPU
1602	bool "Debugging for CPUs failing to respond to backtrace requests"
1603	depends on DEBUG_KERNEL
1604	depends on X86
1605	default n
1606	help
1607	  Enables debug prints when a CPU fails to respond to a given
1608	  backtrace NMI.  These prints provide some reasons why a CPU
1609	  might legitimately be failing to respond, for example, if it
1610	  is offline of if ignore_nmis is set.
1611
1612config DEBUG_IRQFLAGS
1613	bool "Debug IRQ flag manipulation"
1614	help
1615	  Enables checks for potentially unsafe enabling or disabling of
1616	  interrupts, such as calling raw_local_irq_restore() when interrupts
1617	  are enabled.
1618
1619config STACKTRACE
1620	bool "Stack backtrace support"
1621	depends on STACKTRACE_SUPPORT
1622	help
1623	  This option causes the kernel to create a /proc/pid/stack for
1624	  every process, showing its current stack trace.
1625	  It is also used by various kernel debugging features that require
1626	  stack trace generation.
1627
1628config WARN_ALL_UNSEEDED_RANDOM
1629	bool "Warn for all uses of unseeded randomness"
1630	default n
1631	help
1632	  Some parts of the kernel contain bugs relating to their use of
1633	  cryptographically secure random numbers before it's actually possible
1634	  to generate those numbers securely. This setting ensures that these
1635	  flaws don't go unnoticed, by enabling a message, should this ever
1636	  occur. This will allow people with obscure setups to know when things
1637	  are going wrong, so that they might contact developers about fixing
1638	  it.
1639
1640	  Unfortunately, on some models of some architectures getting
1641	  a fully seeded CRNG is extremely difficult, and so this can
1642	  result in dmesg getting spammed for a surprisingly long
1643	  time.  This is really bad from a security perspective, and
1644	  so architecture maintainers really need to do what they can
1645	  to get the CRNG seeded sooner after the system is booted.
1646	  However, since users cannot do anything actionable to
1647	  address this, by default this option is disabled.
1648
1649	  Say Y here if you want to receive warnings for all uses of
1650	  unseeded randomness.  This will be of use primarily for
1651	  those developers interested in improving the security of
1652	  Linux kernels running on their architecture (or
1653	  subarchitecture).
1654
1655config DEBUG_KOBJECT
1656	bool "kobject debugging"
1657	depends on DEBUG_KERNEL
1658	help
1659	  If you say Y here, some extra kobject debugging messages will be sent
1660	  to the syslog.
1661
1662config DEBUG_KOBJECT_RELEASE
1663	bool "kobject release debugging"
1664	depends on DEBUG_OBJECTS_TIMERS
1665	help
1666	  kobjects are reference counted objects.  This means that their
1667	  last reference count put is not predictable, and the kobject can
1668	  live on past the point at which a driver decides to drop its
1669	  initial reference to the kobject gained on allocation.  An
1670	  example of this would be a struct device which has just been
1671	  unregistered.
1672
1673	  However, some buggy drivers assume that after such an operation,
1674	  the memory backing the kobject can be immediately freed.  This
1675	  goes completely against the principles of a refcounted object.
1676
1677	  If you say Y here, the kernel will delay the release of kobjects
1678	  on the last reference count to improve the visibility of this
1679	  kind of kobject release bug.
1680
1681config HAVE_DEBUG_BUGVERBOSE
1682	bool
1683
1684menu "Debug kernel data structures"
1685
1686config DEBUG_LIST
1687	bool "Debug linked list manipulation"
1688	depends on DEBUG_KERNEL
1689	select LIST_HARDENED
1690	help
1691	  Enable this to turn on extended checks in the linked-list walking
1692	  routines.
1693
1694	  This option trades better quality error reports for performance, and
1695	  is more suitable for kernel debugging. If you care about performance,
1696	  you should only enable CONFIG_LIST_HARDENED instead.
1697
1698	  If unsure, say N.
1699
1700config DEBUG_PLIST
1701	bool "Debug priority linked list manipulation"
1702	depends on DEBUG_KERNEL
1703	help
1704	  Enable this to turn on extended checks in the priority-ordered
1705	  linked-list (plist) walking routines.  This checks the entire
1706	  list multiple times during each manipulation.
1707
1708	  If unsure, say N.
1709
1710config DEBUG_SG
1711	bool "Debug SG table operations"
1712	depends on DEBUG_KERNEL
1713	help
1714	  Enable this to turn on checks on scatter-gather tables. This can
1715	  help find problems with drivers that do not properly initialize
1716	  their sg tables.
1717
1718	  If unsure, say N.
1719
1720config DEBUG_NOTIFIERS
1721	bool "Debug notifier call chains"
1722	depends on DEBUG_KERNEL
1723	help
1724	  Enable this to turn on sanity checking for notifier call chains.
1725	  This is most useful for kernel developers to make sure that
1726	  modules properly unregister themselves from notifier chains.
1727	  This is a relatively cheap check but if you care about maximum
1728	  performance, say N.
1729
1730config DEBUG_MAPLE_TREE
1731	bool "Debug maple trees"
1732	depends on DEBUG_KERNEL
1733	help
1734	  Enable maple tree debugging information and extra validations.
1735
1736	  If unsure, say N.
1737
1738endmenu
1739
1740source "kernel/rcu/Kconfig.debug"
1741
1742config DEBUG_WQ_FORCE_RR_CPU
1743	bool "Force round-robin CPU selection for unbound work items"
1744	depends on DEBUG_KERNEL
1745	default n
1746	help
1747	  Workqueue used to implicitly guarantee that work items queued
1748	  without explicit CPU specified are put on the local CPU.  This
1749	  guarantee is no longer true and while local CPU is still
1750	  preferred work items may be put on foreign CPUs.  Kernel
1751	  parameter "workqueue.debug_force_rr_cpu" is added to force
1752	  round-robin CPU selection to flush out usages which depend on the
1753	  now broken guarantee.  This config option enables the debug
1754	  feature by default.  When enabled, memory and cache locality will
1755	  be impacted.
1756
1757config CPU_HOTPLUG_STATE_CONTROL
1758	bool "Enable CPU hotplug state control"
1759	depends on DEBUG_KERNEL
1760	depends on HOTPLUG_CPU
1761	default n
1762	help
1763	  Allows to write steps between "offline" and "online" to the CPUs
1764	  sysfs target file so states can be stepped granular. This is a debug
1765	  option for now as the hotplug machinery cannot be stopped and
1766	  restarted at arbitrary points yet.
1767
1768	  Say N if your are unsure.
1769
1770config LATENCYTOP
1771	bool "Latency measuring infrastructure"
1772	depends on DEBUG_KERNEL
1773	depends on STACKTRACE_SUPPORT
1774	depends on PROC_FS
1775	depends on FRAME_POINTER || MIPS || PPC || S390 || MICROBLAZE || ARM || ARC || X86
1776	select KALLSYMS
1777	select KALLSYMS_ALL
1778	select STACKTRACE
1779	select SCHEDSTATS
1780	help
1781	  Enable this option if you want to use the LatencyTOP tool
1782	  to find out which userspace is blocking on what kernel operations.
1783
1784config DEBUG_CGROUP_REF
1785	bool "Disable inlining of cgroup css reference count functions"
1786	depends on DEBUG_KERNEL
1787	depends on CGROUPS
1788	depends on KPROBES
1789	default n
1790	help
1791	  Force cgroup css reference count functions to not be inlined so
1792	  that they can be kprobed for debugging.
1793
1794source "kernel/trace/Kconfig"
1795
1796config PROVIDE_OHCI1394_DMA_INIT
1797	bool "Remote debugging over FireWire early on boot"
1798	depends on PCI && X86
1799	help
1800	  If you want to debug problems which hang or crash the kernel early
1801	  on boot and the crashing machine has a FireWire port, you can use
1802	  this feature to remotely access the memory of the crashed machine
1803	  over FireWire. This employs remote DMA as part of the OHCI1394
1804	  specification which is now the standard for FireWire controllers.
1805
1806	  With remote DMA, you can monitor the printk buffer remotely using
1807	  firescope and access all memory below 4GB using fireproxy from gdb.
1808	  Even controlling a kernel debugger is possible using remote DMA.
1809
1810	  Usage:
1811
1812	  If ohci1394_dma=early is used as boot parameter, it will initialize
1813	  all OHCI1394 controllers which are found in the PCI config space.
1814
1815	  As all changes to the FireWire bus such as enabling and disabling
1816	  devices cause a bus reset and thereby disable remote DMA for all
1817	  devices, be sure to have the cable plugged and FireWire enabled on
1818	  the debugging host before booting the debug target for debugging.
1819
1820	  This code (~1k) is freed after boot. By then, the firewire stack
1821	  in charge of the OHCI-1394 controllers should be used instead.
1822
1823	  See Documentation/core-api/debugging-via-ohci1394.rst for more information.
1824
1825source "samples/Kconfig"
1826
1827config ARCH_HAS_DEVMEM_IS_ALLOWED
1828	bool
1829
1830config STRICT_DEVMEM
1831	bool "Filter access to /dev/mem"
1832	depends on MMU && DEVMEM
1833	depends on ARCH_HAS_DEVMEM_IS_ALLOWED || GENERIC_LIB_DEVMEM_IS_ALLOWED
1834	default y if PPC || X86 || ARM64
1835	help
1836	  If this option is disabled, you allow userspace (root) access to all
1837	  of memory, including kernel and userspace memory. Accidental
1838	  access to this is obviously disastrous, but specific access can
1839	  be used by people debugging the kernel. Note that with PAT support
1840	  enabled, even in this case there are restrictions on /dev/mem
1841	  use due to the cache aliasing requirements.
1842
1843	  If this option is switched on, and IO_STRICT_DEVMEM=n, the /dev/mem
1844	  file only allows userspace access to PCI space and the BIOS code and
1845	  data regions.  This is sufficient for dosemu and X and all common
1846	  users of /dev/mem.
1847
1848	  If in doubt, say Y.
1849
1850config IO_STRICT_DEVMEM
1851	bool "Filter I/O access to /dev/mem"
1852	depends on STRICT_DEVMEM
1853	help
1854	  If this option is disabled, you allow userspace (root) access to all
1855	  io-memory regardless of whether a driver is actively using that
1856	  range.  Accidental access to this is obviously disastrous, but
1857	  specific access can be used by people debugging kernel drivers.
1858
1859	  If this option is switched on, the /dev/mem file only allows
1860	  userspace access to *idle* io-memory ranges (see /proc/iomem) This
1861	  may break traditional users of /dev/mem (dosemu, legacy X, etc...)
1862	  if the driver using a given range cannot be disabled.
1863
1864	  If in doubt, say Y.
1865
1866menu "$(SRCARCH) Debugging"
1867
1868source "arch/$(SRCARCH)/Kconfig.debug"
1869
1870endmenu
1871
1872menu "Kernel Testing and Coverage"
1873
1874source "lib/kunit/Kconfig"
1875
1876config NOTIFIER_ERROR_INJECTION
1877	tristate "Notifier error injection"
1878	depends on DEBUG_KERNEL
1879	select DEBUG_FS
1880	help
1881	  This option provides the ability to inject artificial errors to
1882	  specified notifier chain callbacks. It is useful to test the error
1883	  handling of notifier call chain failures.
1884
1885	  Say N if unsure.
1886
1887config PM_NOTIFIER_ERROR_INJECT
1888	tristate "PM notifier error injection module"
1889	depends on PM && NOTIFIER_ERROR_INJECTION
1890	default m if PM_DEBUG
1891	help
1892	  This option provides the ability to inject artificial errors to
1893	  PM notifier chain callbacks.  It is controlled through debugfs
1894	  interface /sys/kernel/debug/notifier-error-inject/pm
1895
1896	  If the notifier call chain should be failed with some events
1897	  notified, write the error code to "actions/<notifier event>/error".
1898
1899	  Example: Inject PM suspend error (-12 = -ENOMEM)
1900
1901	  # cd /sys/kernel/debug/notifier-error-inject/pm/
1902	  # echo -12 > actions/PM_SUSPEND_PREPARE/error
1903	  # echo mem > /sys/power/state
1904	  bash: echo: write error: Cannot allocate memory
1905
1906	  To compile this code as a module, choose M here: the module will
1907	  be called pm-notifier-error-inject.
1908
1909	  If unsure, say N.
1910
1911config OF_RECONFIG_NOTIFIER_ERROR_INJECT
1912	tristate "OF reconfig notifier error injection module"
1913	depends on OF_DYNAMIC && NOTIFIER_ERROR_INJECTION
1914	help
1915	  This option provides the ability to inject artificial errors to
1916	  OF reconfig notifier chain callbacks.  It is controlled
1917	  through debugfs interface under
1918	  /sys/kernel/debug/notifier-error-inject/OF-reconfig/
1919
1920	  If the notifier call chain should be failed with some events
1921	  notified, write the error code to "actions/<notifier event>/error".
1922
1923	  To compile this code as a module, choose M here: the module will
1924	  be called of-reconfig-notifier-error-inject.
1925
1926	  If unsure, say N.
1927
1928config NETDEV_NOTIFIER_ERROR_INJECT
1929	tristate "Netdev notifier error injection module"
1930	depends on NET && NOTIFIER_ERROR_INJECTION
1931	help
1932	  This option provides the ability to inject artificial errors to
1933	  netdevice notifier chain callbacks.  It is controlled through debugfs
1934	  interface /sys/kernel/debug/notifier-error-inject/netdev
1935
1936	  If the notifier call chain should be failed with some events
1937	  notified, write the error code to "actions/<notifier event>/error".
1938
1939	  Example: Inject netdevice mtu change error (-22 = -EINVAL)
1940
1941	  # cd /sys/kernel/debug/notifier-error-inject/netdev
1942	  # echo -22 > actions/NETDEV_CHANGEMTU/error
1943	  # ip link set eth0 mtu 1024
1944	  RTNETLINK answers: Invalid argument
1945
1946	  To compile this code as a module, choose M here: the module will
1947	  be called netdev-notifier-error-inject.
1948
1949	  If unsure, say N.
1950
1951config FUNCTION_ERROR_INJECTION
1952	bool "Fault-injections of functions"
1953	depends on HAVE_FUNCTION_ERROR_INJECTION && KPROBES
1954	help
1955	  Add fault injections into various functions that are annotated with
1956	  ALLOW_ERROR_INJECTION() in the kernel. BPF may also modify the return
1957	  value of these functions. This is useful to test error paths of code.
1958
1959	  If unsure, say N
1960
1961config FAULT_INJECTION
1962	bool "Fault-injection framework"
1963	depends on DEBUG_KERNEL
1964	help
1965	  Provide fault-injection framework.
1966	  For more details, see Documentation/fault-injection/.
1967
1968config FAILSLAB
1969	bool "Fault-injection capability for kmalloc"
1970	depends on FAULT_INJECTION
1971	depends on SLAB || SLUB
1972	help
1973	  Provide fault-injection capability for kmalloc.
1974
1975config FAIL_PAGE_ALLOC
1976	bool "Fault-injection capability for alloc_pages()"
1977	depends on FAULT_INJECTION
1978	help
1979	  Provide fault-injection capability for alloc_pages().
1980
1981config FAULT_INJECTION_USERCOPY
1982	bool "Fault injection capability for usercopy functions"
1983	depends on FAULT_INJECTION
1984	help
1985	  Provides fault-injection capability to inject failures
1986	  in usercopy functions (copy_from_user(), get_user(), ...).
1987
1988config FAIL_MAKE_REQUEST
1989	bool "Fault-injection capability for disk IO"
1990	depends on FAULT_INJECTION && BLOCK
1991	help
1992	  Provide fault-injection capability for disk IO.
1993
1994config FAIL_IO_TIMEOUT
1995	bool "Fault-injection capability for faking disk interrupts"
1996	depends on FAULT_INJECTION && BLOCK
1997	help
1998	  Provide fault-injection capability on end IO handling. This
1999	  will make the block layer "forget" an interrupt as configured,
2000	  thus exercising the error handling.
2001
2002	  Only works with drivers that use the generic timeout handling,
2003	  for others it won't do anything.
2004
2005config FAIL_FUTEX
2006	bool "Fault-injection capability for futexes"
2007	select DEBUG_FS
2008	depends on FAULT_INJECTION && FUTEX
2009	help
2010	  Provide fault-injection capability for futexes.
2011
2012config FAULT_INJECTION_DEBUG_FS
2013	bool "Debugfs entries for fault-injection capabilities"
2014	depends on FAULT_INJECTION && SYSFS && DEBUG_FS
2015	help
2016	  Enable configuration of fault-injection capabilities via debugfs.
2017
2018config FAIL_FUNCTION
2019	bool "Fault-injection capability for functions"
2020	depends on FAULT_INJECTION_DEBUG_FS && FUNCTION_ERROR_INJECTION
2021	help
2022	  Provide function-based fault-injection capability.
2023	  This will allow you to override a specific function with a return
2024	  with given return value. As a result, function caller will see
2025	  an error value and have to handle it. This is useful to test the
2026	  error handling in various subsystems.
2027
2028config FAIL_MMC_REQUEST
2029	bool "Fault-injection capability for MMC IO"
2030	depends on FAULT_INJECTION_DEBUG_FS && MMC
2031	help
2032	  Provide fault-injection capability for MMC IO.
2033	  This will make the mmc core return data errors. This is
2034	  useful to test the error handling in the mmc block device
2035	  and to test how the mmc host driver handles retries from
2036	  the block device.
2037
2038config FAIL_SUNRPC
2039	bool "Fault-injection capability for SunRPC"
2040	depends on FAULT_INJECTION_DEBUG_FS && SUNRPC_DEBUG
2041	help
2042	  Provide fault-injection capability for SunRPC and
2043	  its consumers.
2044
2045config FAULT_INJECTION_CONFIGFS
2046	bool "Configfs interface for fault-injection capabilities"
2047	depends on FAULT_INJECTION
2048	select CONFIGFS_FS
2049	help
2050	  This option allows configfs-based drivers to dynamically configure
2051	  fault-injection via configfs.  Each parameter for driver-specific
2052	  fault-injection can be made visible as a configfs attribute in a
2053	  configfs group.
2054
2055
2056config FAULT_INJECTION_STACKTRACE_FILTER
2057	bool "stacktrace filter for fault-injection capabilities"
2058	depends on FAULT_INJECTION
2059	depends on (FAULT_INJECTION_DEBUG_FS || FAULT_INJECTION_CONFIGFS) && STACKTRACE_SUPPORT
2060	select STACKTRACE
2061	depends on FRAME_POINTER || MIPS || PPC || S390 || MICROBLAZE || ARM || ARC || X86
2062	help
2063	  Provide stacktrace filter for fault-injection capabilities
2064
2065config ARCH_HAS_KCOV
2066	bool
2067	help
2068	  An architecture should select this when it can successfully
2069	  build and run with CONFIG_KCOV. This typically requires
2070	  disabling instrumentation for some early boot code.
2071
2072config CC_HAS_SANCOV_TRACE_PC
2073	def_bool $(cc-option,-fsanitize-coverage=trace-pc)
2074
2075
2076config KCOV
2077	bool "Code coverage for fuzzing"
2078	depends on ARCH_HAS_KCOV
2079	depends on CC_HAS_SANCOV_TRACE_PC || GCC_PLUGINS
2080	depends on !ARCH_WANTS_NO_INSTR || HAVE_NOINSTR_HACK || \
2081		   GCC_VERSION >= 120000 || CLANG_VERSION >= 130000
2082	select DEBUG_FS
2083	select GCC_PLUGIN_SANCOV if !CC_HAS_SANCOV_TRACE_PC
2084	select OBJTOOL if HAVE_NOINSTR_HACK
2085	help
2086	  KCOV exposes kernel code coverage information in a form suitable
2087	  for coverage-guided fuzzing (randomized testing).
2088
2089	  If RANDOMIZE_BASE is enabled, PC values will not be stable across
2090	  different machines and across reboots. If you need stable PC values,
2091	  disable RANDOMIZE_BASE.
2092
2093	  For more details, see Documentation/dev-tools/kcov.rst.
2094
2095config KCOV_ENABLE_COMPARISONS
2096	bool "Enable comparison operands collection by KCOV"
2097	depends on KCOV
2098	depends on $(cc-option,-fsanitize-coverage=trace-cmp)
2099	help
2100	  KCOV also exposes operands of every comparison in the instrumented
2101	  code along with operand sizes and PCs of the comparison instructions.
2102	  These operands can be used by fuzzing engines to improve the quality
2103	  of fuzzing coverage.
2104
2105config KCOV_INSTRUMENT_ALL
2106	bool "Instrument all code by default"
2107	depends on KCOV
2108	default y
2109	help
2110	  If you are doing generic system call fuzzing (like e.g. syzkaller),
2111	  then you will want to instrument the whole kernel and you should
2112	  say y here. If you are doing more targeted fuzzing (like e.g.
2113	  filesystem fuzzing with AFL) then you will want to enable coverage
2114	  for more specific subsets of files, and should say n here.
2115
2116config KCOV_IRQ_AREA_SIZE
2117	hex "Size of interrupt coverage collection area in words"
2118	depends on KCOV
2119	default 0x40000
2120	help
2121	  KCOV uses preallocated per-cpu areas to collect coverage from
2122	  soft interrupts. This specifies the size of those areas in the
2123	  number of unsigned long words.
2124
2125menuconfig RUNTIME_TESTING_MENU
2126	bool "Runtime Testing"
2127	def_bool y
2128
2129if RUNTIME_TESTING_MENU
2130
2131config TEST_DHRY
2132	tristate "Dhrystone benchmark test"
2133	help
2134	  Enable this to include the Dhrystone 2.1 benchmark.  This test
2135	  calculates the number of Dhrystones per second, and the number of
2136	  DMIPS (Dhrystone MIPS) obtained when the Dhrystone score is divided
2137	  by 1757 (the number of Dhrystones per second obtained on the VAX
2138	  11/780, nominally a 1 MIPS machine).
2139
2140	  To run the benchmark, it needs to be enabled explicitly, either from
2141	  the kernel command line (when built-in), or from userspace (when
2142	  built-in or modular.
2143
2144	  Run once during kernel boot:
2145
2146	      test_dhry.run
2147
2148	  Set number of iterations from kernel command line:
2149
2150	      test_dhry.iterations=<n>
2151
2152	  Set number of iterations from userspace:
2153
2154	      echo <n> > /sys/module/test_dhry/parameters/iterations
2155
2156	  Trigger manual run from userspace:
2157
2158	      echo y > /sys/module/test_dhry/parameters/run
2159
2160	  If the number of iterations is <= 0, the test will devise a suitable
2161	  number of iterations (test runs for at least 2s) automatically.
2162	  This process takes ca. 4s.
2163
2164	  If unsure, say N.
2165
2166config LKDTM
2167	tristate "Linux Kernel Dump Test Tool Module"
2168	depends on DEBUG_FS
2169	help
2170	This module enables testing of the different dumping mechanisms by
2171	inducing system failures at predefined crash points.
2172	If you don't need it: say N
2173	Choose M here to compile this code as a module. The module will be
2174	called lkdtm.
2175
2176	Documentation on how to use the module can be found in
2177	Documentation/fault-injection/provoke-crashes.rst
2178
2179config CPUMASK_KUNIT_TEST
2180	tristate "KUnit test for cpumask" if !KUNIT_ALL_TESTS
2181	depends on KUNIT
2182	default KUNIT_ALL_TESTS
2183	help
2184	  Enable to turn on cpumask tests, running at boot or module load time.
2185
2186	  For more information on KUnit and unit tests in general, please refer
2187	  to the KUnit documentation in Documentation/dev-tools/kunit/.
2188
2189	  If unsure, say N.
2190
2191config TEST_LIST_SORT
2192	tristate "Linked list sorting test" if !KUNIT_ALL_TESTS
2193	depends on KUNIT
2194	default KUNIT_ALL_TESTS
2195	help
2196	  Enable this to turn on 'list_sort()' function test. This test is
2197	  executed only once during system boot (so affects only boot time),
2198	  or at module load time.
2199
2200	  If unsure, say N.
2201
2202config TEST_MIN_HEAP
2203	tristate "Min heap test"
2204	depends on DEBUG_KERNEL || m
2205	help
2206	  Enable this to turn on min heap function tests. This test is
2207	  executed only once during system boot (so affects only boot time),
2208	  or at module load time.
2209
2210	  If unsure, say N.
2211
2212config TEST_SORT
2213	tristate "Array-based sort test" if !KUNIT_ALL_TESTS
2214	depends on KUNIT
2215	default KUNIT_ALL_TESTS
2216	help
2217	  This option enables the self-test function of 'sort()' at boot,
2218	  or at module load time.
2219
2220	  If unsure, say N.
2221
2222config TEST_DIV64
2223	tristate "64bit/32bit division and modulo test"
2224	depends on DEBUG_KERNEL || m
2225	help
2226	  Enable this to turn on 'do_div()' function test. This test is
2227	  executed only once during system boot (so affects only boot time),
2228	  or at module load time.
2229
2230	  If unsure, say N.
2231
2232config TEST_IOV_ITER
2233	tristate "Test iov_iter operation" if !KUNIT_ALL_TESTS
2234	depends on KUNIT
2235	depends on MMU
2236	default KUNIT_ALL_TESTS
2237	help
2238	  Enable this to turn on testing of the operation of the I/O iterator
2239	  (iov_iter). This test is executed only once during system boot (so
2240	  affects only boot time), or at module load time.
2241
2242	  If unsure, say N.
2243
2244config KPROBES_SANITY_TEST
2245	tristate "Kprobes sanity tests" if !KUNIT_ALL_TESTS
2246	depends on DEBUG_KERNEL
2247	depends on KPROBES
2248	depends on KUNIT
2249	select STACKTRACE if ARCH_CORRECT_STACKTRACE_ON_KRETPROBE
2250	default KUNIT_ALL_TESTS
2251	help
2252	  This option provides for testing basic kprobes functionality on
2253	  boot. Samples of kprobe and kretprobe are inserted and
2254	  verified for functionality.
2255
2256	  Say N if you are unsure.
2257
2258config FPROBE_SANITY_TEST
2259	bool "Self test for fprobe"
2260	depends on DEBUG_KERNEL
2261	depends on FPROBE
2262	depends on KUNIT=y
2263	help
2264	  This option will enable testing the fprobe when the system boot.
2265	  A series of tests are made to verify that the fprobe is functioning
2266	  properly.
2267
2268	  Say N if you are unsure.
2269
2270config BACKTRACE_SELF_TEST
2271	tristate "Self test for the backtrace code"
2272	depends on DEBUG_KERNEL
2273	help
2274	  This option provides a kernel module that can be used to test
2275	  the kernel stack backtrace code. This option is not useful
2276	  for distributions or general kernels, but only for kernel
2277	  developers working on architecture code.
2278
2279	  Note that if you want to also test saved backtraces, you will
2280	  have to enable STACKTRACE as well.
2281
2282	  Say N if you are unsure.
2283
2284config TEST_REF_TRACKER
2285	tristate "Self test for reference tracker"
2286	depends on DEBUG_KERNEL && STACKTRACE_SUPPORT
2287	select REF_TRACKER
2288	help
2289	  This option provides a kernel module performing tests
2290	  using reference tracker infrastructure.
2291
2292	  Say N if you are unsure.
2293
2294config RBTREE_TEST
2295	tristate "Red-Black tree test"
2296	depends on DEBUG_KERNEL
2297	help
2298	  A benchmark measuring the performance of the rbtree library.
2299	  Also includes rbtree invariant checks.
2300
2301config REED_SOLOMON_TEST
2302	tristate "Reed-Solomon library test"
2303	depends on DEBUG_KERNEL || m
2304	select REED_SOLOMON
2305	select REED_SOLOMON_ENC16
2306	select REED_SOLOMON_DEC16
2307	help
2308	  This option enables the self-test function of rslib at boot,
2309	  or at module load time.
2310
2311	  If unsure, say N.
2312
2313config INTERVAL_TREE_TEST
2314	tristate "Interval tree test"
2315	depends on DEBUG_KERNEL
2316	select INTERVAL_TREE
2317	help
2318	  A benchmark measuring the performance of the interval tree library
2319
2320config PERCPU_TEST
2321	tristate "Per cpu operations test"
2322	depends on m && DEBUG_KERNEL
2323	help
2324	  Enable this option to build test module which validates per-cpu
2325	  operations.
2326
2327	  If unsure, say N.
2328
2329config ATOMIC64_SELFTEST
2330	tristate "Perform an atomic64_t self-test"
2331	help
2332	  Enable this option to test the atomic64_t functions at boot or
2333	  at module load time.
2334
2335	  If unsure, say N.
2336
2337config ASYNC_RAID6_TEST
2338	tristate "Self test for hardware accelerated raid6 recovery"
2339	depends on ASYNC_RAID6_RECOV
2340	select ASYNC_MEMCPY
2341	help
2342	  This is a one-shot self test that permutes through the
2343	  recovery of all the possible two disk failure scenarios for a
2344	  N-disk array.  Recovery is performed with the asynchronous
2345	  raid6 recovery routines, and will optionally use an offload
2346	  engine if one is available.
2347
2348	  If unsure, say N.
2349
2350config TEST_HEXDUMP
2351	tristate "Test functions located in the hexdump module at runtime"
2352
2353config STRING_SELFTEST
2354	tristate "Test string functions at runtime"
2355
2356config TEST_STRING_HELPERS
2357	tristate "Test functions located in the string_helpers module at runtime"
2358
2359config TEST_KSTRTOX
2360	tristate "Test kstrto*() family of functions at runtime"
2361
2362config TEST_PRINTF
2363	tristate "Test printf() family of functions at runtime"
2364
2365config TEST_SCANF
2366	tristate "Test scanf() family of functions at runtime"
2367
2368config TEST_BITMAP
2369	tristate "Test bitmap_*() family of functions at runtime"
2370	help
2371	  Enable this option to test the bitmap functions at boot.
2372
2373	  If unsure, say N.
2374
2375config TEST_UUID
2376	tristate "Test functions located in the uuid module at runtime"
2377
2378config TEST_XARRAY
2379	tristate "Test the XArray code at runtime"
2380
2381config TEST_MAPLE_TREE
2382	tristate "Test the Maple Tree code at runtime or module load"
2383	help
2384	  Enable this option to test the maple tree code functions at boot, or
2385	  when the module is loaded. Enable "Debug Maple Trees" will enable
2386	  more verbose output on failures.
2387
2388	  If unsure, say N.
2389
2390config TEST_RHASHTABLE
2391	tristate "Perform selftest on resizable hash table"
2392	help
2393	  Enable this option to test the rhashtable functions at boot.
2394
2395	  If unsure, say N.
2396
2397config TEST_IDA
2398	tristate "Perform selftest on IDA functions"
2399
2400config TEST_PARMAN
2401	tristate "Perform selftest on priority array manager"
2402	depends on PARMAN
2403	help
2404	  Enable this option to test priority array manager on boot
2405	  (or module load).
2406
2407	  If unsure, say N.
2408
2409config TEST_IRQ_TIMINGS
2410	bool "IRQ timings selftest"
2411	depends on IRQ_TIMINGS
2412	help
2413	  Enable this option to test the irq timings code on boot.
2414
2415	  If unsure, say N.
2416
2417config TEST_LKM
2418	tristate "Test module loading with 'hello world' module"
2419	depends on m
2420	help
2421	  This builds the "test_module" module that emits "Hello, world"
2422	  on printk when loaded. It is designed to be used for basic
2423	  evaluation of the module loading subsystem (for example when
2424	  validating module verification). It lacks any extra dependencies,
2425	  and will not normally be loaded by the system unless explicitly
2426	  requested by name.
2427
2428	  If unsure, say N.
2429
2430config TEST_BITOPS
2431	tristate "Test module for compilation of bitops operations"
2432	depends on m
2433	help
2434	  This builds the "test_bitops" module that is much like the
2435	  TEST_LKM module except that it does a basic exercise of the
2436	  set/clear_bit macros and get_count_order/long to make sure there are
2437	  no compiler warnings from C=1 sparse checker or -Wextra
2438	  compilations. It has no dependencies and doesn't run or load unless
2439	  explicitly requested by name.  for example: modprobe test_bitops.
2440
2441	  If unsure, say N.
2442
2443config TEST_VMALLOC
2444	tristate "Test module for stress/performance analysis of vmalloc allocator"
2445	default n
2446       depends on MMU
2447	depends on m
2448	help
2449	  This builds the "test_vmalloc" module that should be used for
2450	  stress and performance analysis. So, any new change for vmalloc
2451	  subsystem can be evaluated from performance and stability point
2452	  of view.
2453
2454	  If unsure, say N.
2455
2456config TEST_USER_COPY
2457	tristate "Test user/kernel boundary protections"
2458	depends on m
2459	help
2460	  This builds the "test_user_copy" module that runs sanity checks
2461	  on the copy_to/from_user infrastructure, making sure basic
2462	  user/kernel boundary testing is working. If it fails to load,
2463	  a regression has been detected in the user/kernel memory boundary
2464	  protections.
2465
2466	  If unsure, say N.
2467
2468config TEST_BPF
2469	tristate "Test BPF filter functionality"
2470	depends on m && NET
2471	help
2472	  This builds the "test_bpf" module that runs various test vectors
2473	  against the BPF interpreter or BPF JIT compiler depending on the
2474	  current setting. This is in particular useful for BPF JIT compiler
2475	  development, but also to run regression tests against changes in
2476	  the interpreter code. It also enables test stubs for eBPF maps and
2477	  verifier used by user space verifier testsuite.
2478
2479	  If unsure, say N.
2480
2481config TEST_BLACKHOLE_DEV
2482	tristate "Test blackhole netdev functionality"
2483	depends on m && NET
2484	help
2485	  This builds the "test_blackhole_dev" module that validates the
2486	  data path through this blackhole netdev.
2487
2488	  If unsure, say N.
2489
2490config FIND_BIT_BENCHMARK
2491	tristate "Test find_bit functions"
2492	help
2493	  This builds the "test_find_bit" module that measure find_*_bit()
2494	  functions performance.
2495
2496	  If unsure, say N.
2497
2498config TEST_FIRMWARE
2499	tristate "Test firmware loading via userspace interface"
2500	depends on FW_LOADER
2501	help
2502	  This builds the "test_firmware" module that creates a userspace
2503	  interface for testing firmware loading. This can be used to
2504	  control the triggering of firmware loading without needing an
2505	  actual firmware-using device. The contents can be rechecked by
2506	  userspace.
2507
2508	  If unsure, say N.
2509
2510config TEST_SYSCTL
2511	tristate "sysctl test driver"
2512	depends on PROC_SYSCTL
2513	help
2514	  This builds the "test_sysctl" module. This driver enables to test the
2515	  proc sysctl interfaces available to drivers safely without affecting
2516	  production knobs which might alter system functionality.
2517
2518	  If unsure, say N.
2519
2520config BITFIELD_KUNIT
2521	tristate "KUnit test bitfield functions at runtime" if !KUNIT_ALL_TESTS
2522	depends on KUNIT
2523	default KUNIT_ALL_TESTS
2524	help
2525	  Enable this option to test the bitfield functions at boot.
2526
2527	  KUnit tests run during boot and output the results to the debug log
2528	  in TAP format (http://testanything.org/). Only useful for kernel devs
2529	  running the KUnit test harness, and not intended for inclusion into a
2530	  production build.
2531
2532	  For more information on KUnit and unit tests in general please refer
2533	  to the KUnit documentation in Documentation/dev-tools/kunit/.
2534
2535	  If unsure, say N.
2536
2537config CHECKSUM_KUNIT
2538	tristate "KUnit test checksum functions at runtime" if !KUNIT_ALL_TESTS
2539	depends on KUNIT
2540	default KUNIT_ALL_TESTS
2541	help
2542	  Enable this option to test the checksum functions at boot.
2543
2544	  KUnit tests run during boot and output the results to the debug log
2545	  in TAP format (http://testanything.org/). Only useful for kernel devs
2546	  running the KUnit test harness, and not intended for inclusion into a
2547	  production build.
2548
2549	  For more information on KUnit and unit tests in general please refer
2550	  to the KUnit documentation in Documentation/dev-tools/kunit/.
2551
2552	  If unsure, say N.
2553
2554config HASH_KUNIT_TEST
2555	tristate "KUnit Test for integer hash functions" if !KUNIT_ALL_TESTS
2556	depends on KUNIT
2557	default KUNIT_ALL_TESTS
2558	help
2559	  Enable this option to test the kernel's string (<linux/stringhash.h>), and
2560	  integer (<linux/hash.h>) hash functions on boot.
2561
2562	  KUnit tests run during boot and output the results to the debug log
2563	  in TAP format (https://testanything.org/). Only useful for kernel devs
2564	  running the KUnit test harness, and not intended for inclusion into a
2565	  production build.
2566
2567	  For more information on KUnit and unit tests in general please refer
2568	  to the KUnit documentation in Documentation/dev-tools/kunit/.
2569
2570	  This is intended to help people writing architecture-specific
2571	  optimized versions. If unsure, say N.
2572
2573config RESOURCE_KUNIT_TEST
2574	tristate "KUnit test for resource API" if !KUNIT_ALL_TESTS
2575	depends on KUNIT
2576	default KUNIT_ALL_TESTS
2577	help
2578	  This builds the resource API unit test.
2579	  Tests the logic of API provided by resource.c and ioport.h.
2580	  For more information on KUnit and unit tests in general please refer
2581	  to the KUnit documentation in Documentation/dev-tools/kunit/.
2582
2583	  If unsure, say N.
2584
2585config SYSCTL_KUNIT_TEST
2586	tristate "KUnit test for sysctl" if !KUNIT_ALL_TESTS
2587	depends on KUNIT
2588	default KUNIT_ALL_TESTS
2589	help
2590	  This builds the proc sysctl unit test, which runs on boot.
2591	  Tests the API contract and implementation correctness of sysctl.
2592	  For more information on KUnit and unit tests in general please refer
2593	  to the KUnit documentation in Documentation/dev-tools/kunit/.
2594
2595	  If unsure, say N.
2596
2597config LIST_KUNIT_TEST
2598	tristate "KUnit Test for Kernel Linked-list structures" if !KUNIT_ALL_TESTS
2599	depends on KUNIT
2600	default KUNIT_ALL_TESTS
2601	help
2602	  This builds the linked list KUnit test suite.
2603	  It tests that the API and basic functionality of the list_head type
2604	  and associated macros.
2605
2606	  KUnit tests run during boot and output the results to the debug log
2607	  in TAP format (https://testanything.org/). Only useful for kernel devs
2608	  running the KUnit test harness, and not intended for inclusion into a
2609	  production build.
2610
2611	  For more information on KUnit and unit tests in general please refer
2612	  to the KUnit documentation in Documentation/dev-tools/kunit/.
2613
2614	  If unsure, say N.
2615
2616config HASHTABLE_KUNIT_TEST
2617	tristate "KUnit Test for Kernel Hashtable structures" if !KUNIT_ALL_TESTS
2618	depends on KUNIT
2619	default KUNIT_ALL_TESTS
2620	help
2621	  This builds the hashtable KUnit test suite.
2622	  It tests the basic functionality of the API defined in
2623	  include/linux/hashtable.h. For more information on KUnit and
2624	  unit tests in general please refer to the KUnit documentation
2625	  in Documentation/dev-tools/kunit/.
2626
2627	  If unsure, say N.
2628
2629config LINEAR_RANGES_TEST
2630	tristate "KUnit test for linear_ranges"
2631	depends on KUNIT
2632	select LINEAR_RANGES
2633	help
2634	  This builds the linear_ranges unit test, which runs on boot.
2635	  Tests the linear_ranges logic correctness.
2636	  For more information on KUnit and unit tests in general please refer
2637	  to the KUnit documentation in Documentation/dev-tools/kunit/.
2638
2639	  If unsure, say N.
2640
2641config CMDLINE_KUNIT_TEST
2642	tristate "KUnit test for cmdline API" if !KUNIT_ALL_TESTS
2643	depends on KUNIT
2644	default KUNIT_ALL_TESTS
2645	help
2646	  This builds the cmdline API unit test.
2647	  Tests the logic of API provided by cmdline.c.
2648	  For more information on KUnit and unit tests in general please refer
2649	  to the KUnit documentation in Documentation/dev-tools/kunit/.
2650
2651	  If unsure, say N.
2652
2653config BITS_TEST
2654	tristate "KUnit test for bits.h" if !KUNIT_ALL_TESTS
2655	depends on KUNIT
2656	default KUNIT_ALL_TESTS
2657	help
2658	  This builds the bits unit test.
2659	  Tests the logic of macros defined in bits.h.
2660	  For more information on KUnit and unit tests in general please refer
2661	  to the KUnit documentation in Documentation/dev-tools/kunit/.
2662
2663	  If unsure, say N.
2664
2665config SLUB_KUNIT_TEST
2666	tristate "KUnit test for SLUB cache error detection" if !KUNIT_ALL_TESTS
2667	depends on SLUB_DEBUG && KUNIT
2668	default KUNIT_ALL_TESTS
2669	help
2670	  This builds SLUB allocator unit test.
2671	  Tests SLUB cache debugging functionality.
2672	  For more information on KUnit and unit tests in general please refer
2673	  to the KUnit documentation in Documentation/dev-tools/kunit/.
2674
2675	  If unsure, say N.
2676
2677config RATIONAL_KUNIT_TEST
2678	tristate "KUnit test for rational.c" if !KUNIT_ALL_TESTS
2679	depends on KUNIT && RATIONAL
2680	default KUNIT_ALL_TESTS
2681	help
2682	  This builds the rational math unit test.
2683	  For more information on KUnit and unit tests in general please refer
2684	  to the KUnit documentation in Documentation/dev-tools/kunit/.
2685
2686	  If unsure, say N.
2687
2688config MEMCPY_KUNIT_TEST
2689	tristate "Test memcpy(), memmove(), and memset() functions at runtime" if !KUNIT_ALL_TESTS
2690	depends on KUNIT
2691	default KUNIT_ALL_TESTS
2692	help
2693	  Builds unit tests for memcpy(), memmove(), and memset() functions.
2694	  For more information on KUnit and unit tests in general please refer
2695	  to the KUnit documentation in Documentation/dev-tools/kunit/.
2696
2697	  If unsure, say N.
2698
2699config MEMCPY_SLOW_KUNIT_TEST
2700	bool "Include exhaustive memcpy tests"
2701	depends on MEMCPY_KUNIT_TEST
2702	default y
2703	help
2704	  Some memcpy tests are quite exhaustive in checking for overlaps
2705	  and bit ranges. These can be very slow, so they are split out
2706	  as a separate config, in case they need to be disabled.
2707
2708	  Note this config option will be replaced by the use of KUnit test
2709	  attributes.
2710
2711config IS_SIGNED_TYPE_KUNIT_TEST
2712	tristate "Test is_signed_type() macro" if !KUNIT_ALL_TESTS
2713	depends on KUNIT
2714	default KUNIT_ALL_TESTS
2715	help
2716	  Builds unit tests for the is_signed_type() macro.
2717
2718	  For more information on KUnit and unit tests in general please refer
2719	  to the KUnit documentation in Documentation/dev-tools/kunit/.
2720
2721	  If unsure, say N.
2722
2723config OVERFLOW_KUNIT_TEST
2724	tristate "Test check_*_overflow() functions at runtime" if !KUNIT_ALL_TESTS
2725	depends on KUNIT
2726	default KUNIT_ALL_TESTS
2727	help
2728	  Builds unit tests for the check_*_overflow(), size_*(), allocation, and
2729	  related functions.
2730
2731	  For more information on KUnit and unit tests in general please refer
2732	  to the KUnit documentation in Documentation/dev-tools/kunit/.
2733
2734	  If unsure, say N.
2735
2736config STACKINIT_KUNIT_TEST
2737	tristate "Test level of stack variable initialization" if !KUNIT_ALL_TESTS
2738	depends on KUNIT
2739	default KUNIT_ALL_TESTS
2740	help
2741	  Test if the kernel is zero-initializing stack variables and
2742	  padding. Coverage is controlled by compiler flags,
2743	  CONFIG_INIT_STACK_ALL_PATTERN, CONFIG_INIT_STACK_ALL_ZERO,
2744	  CONFIG_GCC_PLUGIN_STRUCTLEAK, CONFIG_GCC_PLUGIN_STRUCTLEAK_BYREF,
2745	  or CONFIG_GCC_PLUGIN_STRUCTLEAK_BYREF_ALL.
2746
2747config FORTIFY_KUNIT_TEST
2748	tristate "Test fortified str*() and mem*() function internals at runtime" if !KUNIT_ALL_TESTS
2749	depends on KUNIT && FORTIFY_SOURCE
2750	default KUNIT_ALL_TESTS
2751	help
2752	  Builds unit tests for checking internals of FORTIFY_SOURCE as used
2753	  by the str*() and mem*() family of functions. For testing runtime
2754	  traps of FORTIFY_SOURCE, see LKDTM's "FORTIFY_*" tests.
2755
2756config HW_BREAKPOINT_KUNIT_TEST
2757	bool "Test hw_breakpoint constraints accounting" if !KUNIT_ALL_TESTS
2758	depends on HAVE_HW_BREAKPOINT
2759	depends on KUNIT=y
2760	default KUNIT_ALL_TESTS
2761	help
2762	  Tests for hw_breakpoint constraints accounting.
2763
2764	  If unsure, say N.
2765
2766config STRCAT_KUNIT_TEST
2767	tristate "Test strcat() family of functions at runtime" if !KUNIT_ALL_TESTS
2768	depends on KUNIT
2769	default KUNIT_ALL_TESTS
2770
2771config STRSCPY_KUNIT_TEST
2772	tristate "Test strscpy*() family of functions at runtime" if !KUNIT_ALL_TESTS
2773	depends on KUNIT
2774	default KUNIT_ALL_TESTS
2775
2776config SIPHASH_KUNIT_TEST
2777	tristate "Perform selftest on siphash functions" if !KUNIT_ALL_TESTS
2778	depends on KUNIT
2779	default KUNIT_ALL_TESTS
2780	help
2781	  Enable this option to test the kernel's siphash (<linux/siphash.h>) hash
2782	  functions on boot (or module load).
2783
2784	  This is intended to help people writing architecture-specific
2785	  optimized versions.  If unsure, say N.
2786
2787config TEST_UDELAY
2788	tristate "udelay test driver"
2789	help
2790	  This builds the "udelay_test" module that helps to make sure
2791	  that udelay() is working properly.
2792
2793	  If unsure, say N.
2794
2795config TEST_STATIC_KEYS
2796	tristate "Test static keys"
2797	depends on m
2798	help
2799	  Test the static key interfaces.
2800
2801	  If unsure, say N.
2802
2803config TEST_DYNAMIC_DEBUG
2804	tristate "Test DYNAMIC_DEBUG"
2805	depends on DYNAMIC_DEBUG
2806	help
2807	  This module registers a tracer callback to count enabled
2808	  pr_debugs in a 'do_debugging' function, then alters their
2809	  enablements, calls the function, and compares counts.
2810
2811	  If unsure, say N.
2812
2813config TEST_KMOD
2814	tristate "kmod stress tester"
2815	depends on m
2816	depends on NETDEVICES && NET_CORE && INET # for TUN
2817	depends on BLOCK
2818	depends on PAGE_SIZE_LESS_THAN_256KB # for BTRFS
2819	select TEST_LKM
2820	select XFS_FS
2821	select TUN
2822	select BTRFS_FS
2823	help
2824	  Test the kernel's module loading mechanism: kmod. kmod implements
2825	  support to load modules using the Linux kernel's usermode helper.
2826	  This test provides a series of tests against kmod.
2827
2828	  Although technically you can either build test_kmod as a module or
2829	  into the kernel we disallow building it into the kernel since
2830	  it stress tests request_module() and this will very likely cause
2831	  some issues by taking over precious threads available from other
2832	  module load requests, ultimately this could be fatal.
2833
2834	  To run tests run:
2835
2836	  tools/testing/selftests/kmod/kmod.sh --help
2837
2838	  If unsure, say N.
2839
2840config TEST_DEBUG_VIRTUAL
2841	tristate "Test CONFIG_DEBUG_VIRTUAL feature"
2842	depends on DEBUG_VIRTUAL
2843	help
2844	  Test the kernel's ability to detect incorrect calls to
2845	  virt_to_phys() done against the non-linear part of the
2846	  kernel's virtual address map.
2847
2848	  If unsure, say N.
2849
2850config TEST_MEMCAT_P
2851	tristate "Test memcat_p() helper function"
2852	help
2853	  Test the memcat_p() helper for correctly merging two
2854	  pointer arrays together.
2855
2856	  If unsure, say N.
2857
2858config TEST_LIVEPATCH
2859	tristate "Test livepatching"
2860	default n
2861	depends on DYNAMIC_DEBUG
2862	depends on LIVEPATCH
2863	depends on m
2864	help
2865	  Test kernel livepatching features for correctness.  The tests will
2866	  load test modules that will be livepatched in various scenarios.
2867
2868	  To run all the livepatching tests:
2869
2870	  make -C tools/testing/selftests TARGETS=livepatch run_tests
2871
2872	  Alternatively, individual tests may be invoked:
2873
2874	  tools/testing/selftests/livepatch/test-callbacks.sh
2875	  tools/testing/selftests/livepatch/test-livepatch.sh
2876	  tools/testing/selftests/livepatch/test-shadow-vars.sh
2877
2878	  If unsure, say N.
2879
2880config TEST_OBJAGG
2881	tristate "Perform selftest on object aggreration manager"
2882	default n
2883	depends on OBJAGG
2884	help
2885	  Enable this option to test object aggregation manager on boot
2886	  (or module load).
2887
2888config TEST_MEMINIT
2889	tristate "Test heap/page initialization"
2890	help
2891	  Test if the kernel is zero-initializing heap and page allocations.
2892	  This can be useful to test init_on_alloc and init_on_free features.
2893
2894	  If unsure, say N.
2895
2896config TEST_HMM
2897	tristate "Test HMM (Heterogeneous Memory Management)"
2898	depends on TRANSPARENT_HUGEPAGE
2899	depends on DEVICE_PRIVATE
2900	select HMM_MIRROR
2901	select MMU_NOTIFIER
2902	help
2903	  This is a pseudo device driver solely for testing HMM.
2904	  Say M here if you want to build the HMM test module.
2905	  Doing so will allow you to run tools/testing/selftest/vm/hmm-tests.
2906
2907	  If unsure, say N.
2908
2909config TEST_FREE_PAGES
2910	tristate "Test freeing pages"
2911	help
2912	  Test that a memory leak does not occur due to a race between
2913	  freeing a block of pages and a speculative page reference.
2914	  Loading this module is safe if your kernel has the bug fixed.
2915	  If the bug is not fixed, it will leak gigabytes of memory and
2916	  probably OOM your system.
2917
2918config TEST_FPU
2919	tristate "Test floating point operations in kernel space"
2920	depends on X86 && !KCOV_INSTRUMENT_ALL
2921	help
2922	  Enable this option to add /sys/kernel/debug/selftest_helpers/test_fpu
2923	  which will trigger a sequence of floating point operations. This is used
2924	  for self-testing floating point control register setting in
2925	  kernel_fpu_begin().
2926
2927	  If unsure, say N.
2928
2929config TEST_CLOCKSOURCE_WATCHDOG
2930	tristate "Test clocksource watchdog in kernel space"
2931	depends on CLOCKSOURCE_WATCHDOG
2932	help
2933	  Enable this option to create a kernel module that will trigger
2934	  a test of the clocksource watchdog.  This module may be loaded
2935	  via modprobe or insmod in which case it will run upon being
2936	  loaded, or it may be built in, in which case it will run
2937	  shortly after boot.
2938
2939	  If unsure, say N.
2940
2941endif # RUNTIME_TESTING_MENU
2942
2943config ARCH_USE_MEMTEST
2944	bool
2945	help
2946	  An architecture should select this when it uses early_memtest()
2947	  during boot process.
2948
2949config MEMTEST
2950	bool "Memtest"
2951	depends on ARCH_USE_MEMTEST
2952	help
2953	  This option adds a kernel parameter 'memtest', which allows memtest
2954	  to be set and executed.
2955	        memtest=0, mean disabled; -- default
2956	        memtest=1, mean do 1 test pattern;
2957	        ...
2958	        memtest=17, mean do 17 test patterns.
2959	  If you are unsure how to answer this question, answer N.
2960
2961
2962
2963config HYPERV_TESTING
2964	bool "Microsoft Hyper-V driver testing"
2965	default n
2966	depends on HYPERV && DEBUG_FS
2967	help
2968	  Select this option to enable Hyper-V vmbus testing.
2969
2970endmenu # "Kernel Testing and Coverage"
2971
2972menu "Rust hacking"
2973
2974config RUST_DEBUG_ASSERTIONS
2975	bool "Debug assertions"
2976	depends on RUST
2977	help
2978	  Enables rustc's `-Cdebug-assertions` codegen option.
2979
2980	  This flag lets you turn `cfg(debug_assertions)` conditional
2981	  compilation on or off. This can be used to enable extra debugging
2982	  code in development but not in production. For example, it controls
2983	  the behavior of the standard library's `debug_assert!` macro.
2984
2985	  Note that this will apply to all Rust code, including `core`.
2986
2987	  If unsure, say N.
2988
2989config RUST_OVERFLOW_CHECKS
2990	bool "Overflow checks"
2991	default y
2992	depends on RUST
2993	help
2994	  Enables rustc's `-Coverflow-checks` codegen option.
2995
2996	  This flag allows you to control the behavior of runtime integer
2997	  overflow. When overflow-checks are enabled, a Rust panic will occur
2998	  on overflow.
2999
3000	  Note that this will apply to all Rust code, including `core`.
3001
3002	  If unsure, say Y.
3003
3004config RUST_BUILD_ASSERT_ALLOW
3005	bool "Allow unoptimized build-time assertions"
3006	depends on RUST
3007	help
3008	  Controls how are `build_error!` and `build_assert!` handled during build.
3009
3010	  If calls to them exist in the binary, it may indicate a violated invariant
3011	  or that the optimizer failed to verify the invariant during compilation.
3012
3013	  This should not happen, thus by default the build is aborted. However,
3014	  as an escape hatch, you can choose Y here to ignore them during build
3015	  and let the check be carried at runtime (with `panic!` being called if
3016	  the check fails).
3017
3018	  If unsure, say N.
3019
3020config RUST_KERNEL_DOCTESTS
3021	bool "Doctests for the `kernel` crate" if !KUNIT_ALL_TESTS
3022	depends on RUST && KUNIT=y
3023	default KUNIT_ALL_TESTS
3024	help
3025	  This builds the documentation tests of the `kernel` crate
3026	  as KUnit tests.
3027
3028	  For more information on KUnit and unit tests in general,
3029	  please refer to the KUnit documentation in Documentation/dev-tools/kunit/.
3030
3031	  If unsure, say N.
3032
3033endmenu # "Rust"
3034
3035endmenu # Kernel hacking
3036