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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 type information"
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	bool "Generate BTF type information for kernel modules"
408	default y
409	depends on DEBUG_INFO_BTF && MODULES && PAHOLE_HAS_SPLIT_BTF
410	help
411	  Generate compact split BTF type information for kernel modules.
412
413config MODULE_ALLOW_BTF_MISMATCH
414	bool "Allow loading modules with non-matching BTF type info"
415	depends on DEBUG_INFO_BTF_MODULES
416	help
417	  For modules whose split BTF does not match vmlinux, load without
418	  BTF rather than refusing to load. The default behavior with
419	  module BTF enabled is to reject modules with such mismatches;
420	  this option will still load module BTF where possible but ignore
421	  it when a mismatch is found.
422
423config GDB_SCRIPTS
424	bool "Provide GDB scripts for kernel debugging"
425	help
426	  This creates the required links to GDB helper scripts in the
427	  build directory. If you load vmlinux into gdb, the helper
428	  scripts will be automatically imported by gdb as well, and
429	  additional functions are available to analyze a Linux kernel
430	  instance. See Documentation/dev-tools/gdb-kernel-debugging.rst
431	  for further details.
432
433endif # DEBUG_INFO
434
435config FRAME_WARN
436	int "Warn for stack frames larger than"
437	range 0 8192
438	default 0 if KMSAN
439	default 2048 if GCC_PLUGIN_LATENT_ENTROPY
440	default 2048 if PARISC
441	default 1536 if (!64BIT && XTENSA)
442	default 1280 if KASAN && !64BIT
443	default 1024 if !64BIT
444	default 2048 if 64BIT
445	help
446	  Tell the compiler to warn at build time for stack frames larger than this.
447	  Setting this too low will cause a lot of warnings.
448	  Setting it to 0 disables the warning.
449
450config STRIP_ASM_SYMS
451	bool "Strip assembler-generated symbols during link"
452	default n
453	help
454	  Strip internal assembler-generated symbols during a link (symbols
455	  that look like '.Lxxx') so they don't pollute the output of
456	  get_wchan() and suchlike.
457
458config READABLE_ASM
459	bool "Generate readable assembler code"
460	depends on DEBUG_KERNEL
461	depends on CC_IS_GCC
462	help
463	  Disable some compiler optimizations that tend to generate human unreadable
464	  assembler output. This may make the kernel slightly slower, but it helps
465	  to keep kernel developers who have to stare a lot at assembler listings
466	  sane.
467
468config HEADERS_INSTALL
469	bool "Install uapi headers to usr/include"
470	depends on !UML
471	help
472	  This option will install uapi headers (headers exported to user-space)
473	  into the usr/include directory for use during the kernel build.
474	  This is unneeded for building the kernel itself, but needed for some
475	  user-space program samples. It is also needed by some features such
476	  as uapi header sanity checks.
477
478config DEBUG_SECTION_MISMATCH
479	bool "Enable full Section mismatch analysis"
480	depends on CC_IS_GCC
481	help
482	  The section mismatch analysis checks if there are illegal
483	  references from one section to another section.
484	  During linktime or runtime, some sections are dropped;
485	  any use of code/data previously in these sections would
486	  most likely result in an oops.
487	  In the code, functions and variables are annotated with
488	  __init,, etc. (see the full list in include/linux/init.h),
489	  which results in the code/data being placed in specific sections.
490	  The section mismatch analysis is always performed after a full
491	  kernel build, and enabling this option causes the following
492	  additional step to occur:
493	  - Add the option -fno-inline-functions-called-once to gcc commands.
494	    When inlining a function annotated with __init in a non-init
495	    function, we would lose the section information and thus
496	    the analysis would not catch the illegal reference.
497	    This option tells gcc to inline less (but it does result in
498	    a larger kernel).
499
500config SECTION_MISMATCH_WARN_ONLY
501	bool "Make section mismatch errors non-fatal"
502	default y
503	help
504	  If you say N here, the build process will fail if there are any
505	  section mismatch, instead of just throwing warnings.
506
507	  If unsure, say Y.
508
509config DEBUG_FORCE_FUNCTION_ALIGN_64B
510	bool "Force all function address 64B aligned"
511	depends on EXPERT && (X86_64 || ARM64 || PPC32 || PPC64 || ARC || RISCV || S390)
512	select FUNCTION_ALIGNMENT_64B
513	help
514	  There are cases that a commit from one domain changes the function
515	  address alignment of other domains, and cause magic performance
516	  bump (regression or improvement). Enable this option will help to
517	  verify if the bump is caused by function alignment changes, while
518	  it will slightly increase the kernel size and affect icache usage.
519
520	  It is mainly for debug and performance tuning use.
521
522#
523# Select this config option from the architecture Kconfig, if it
524# is preferred to always offer frame pointers as a config
525# option on the architecture (regardless of KERNEL_DEBUG):
526#
527config ARCH_WANT_FRAME_POINTERS
528	bool
529
530config FRAME_POINTER
531	bool "Compile the kernel with frame pointers"
532	depends on DEBUG_KERNEL && (M68K || UML || SUPERH) || ARCH_WANT_FRAME_POINTERS
533	default y if (DEBUG_INFO && UML) || ARCH_WANT_FRAME_POINTERS
534	help
535	  If you say Y here the resulting kernel image will be slightly
536	  larger and slower, but it gives very useful debugging information
537	  in case of kernel bugs. (precise oopses/stacktraces/warnings)
538
539config OBJTOOL
540	bool
541
542config STACK_VALIDATION
543	bool "Compile-time stack metadata validation"
544	depends on HAVE_STACK_VALIDATION && UNWINDER_FRAME_POINTER
545	select OBJTOOL
546	default n
547	help
548	  Validate frame pointer rules at compile-time.  This helps ensure that
549	  runtime stack traces are more reliable.
550
551	  For more information, see
552	  tools/objtool/Documentation/objtool.txt.
553
554config NOINSTR_VALIDATION
555	bool
556	depends on HAVE_NOINSTR_VALIDATION && DEBUG_ENTRY
557	select OBJTOOL
558	default y
559
560config VMLINUX_MAP
561	bool "Generate vmlinux.map file when linking"
562	depends on EXPERT
563	help
564	  Selecting this option will pass "-Map=vmlinux.map" to ld
565	  when linking vmlinux. That file can be useful for verifying
566	  and debugging magic section games, and for seeing which
567	  pieces of code get eliminated with
568	  CONFIG_LD_DEAD_CODE_DATA_ELIMINATION.
569
570config DEBUG_FORCE_WEAK_PER_CPU
571	bool "Force weak per-cpu definitions"
572	depends on DEBUG_KERNEL
573	help
574	  s390 and alpha require percpu variables in modules to be
575	  defined weak to work around addressing range issue which
576	  puts the following two restrictions on percpu variable
577	  definitions.
578
579	  1. percpu symbols must be unique whether static or not
580	  2. percpu variables can't be defined inside a function
581
582	  To ensure that generic code follows the above rules, this
583	  option forces all percpu variables to be defined as weak.
584
585endmenu # "Compiler options"
586
587menu "Generic Kernel Debugging Instruments"
588
589config MAGIC_SYSRQ
590	bool "Magic SysRq key"
591	depends on !UML
592	help
593	  If you say Y here, you will have some control over the system even
594	  if the system crashes for example during kernel debugging (e.g., you
595	  will be able to flush the buffer cache to disk, reboot the system
596	  immediately or dump some status information). This is accomplished
597	  by pressing various keys while holding SysRq (Alt+PrintScreen). It
598	  also works on a serial console (on PC hardware at least), if you
599	  send a BREAK and then within 5 seconds a command keypress. The
600	  keys are documented in <file:Documentation/admin-guide/sysrq.rst>.
601	  Don't say Y unless you really know what this hack does.
602
603config MAGIC_SYSRQ_DEFAULT_ENABLE
604	hex "Enable magic SysRq key functions by default"
605	depends on MAGIC_SYSRQ
606	default 0x1
607	help
608	  Specifies which SysRq key functions are enabled by default.
609	  This may be set to 1 or 0 to enable or disable them all, or
610	  to a bitmask as described in Documentation/admin-guide/sysrq.rst.
611
612config MAGIC_SYSRQ_SERIAL
613	bool "Enable magic SysRq key over serial"
614	depends on MAGIC_SYSRQ
615	default y
616	help
617	  Many embedded boards have a disconnected TTL level serial which can
618	  generate some garbage that can lead to spurious false sysrq detects.
619	  This option allows you to decide whether you want to enable the
620	  magic SysRq key.
621
622config MAGIC_SYSRQ_SERIAL_SEQUENCE
623	string "Char sequence that enables magic SysRq over serial"
624	depends on MAGIC_SYSRQ_SERIAL
625	default ""
626	help
627	  Specifies a sequence of characters that can follow BREAK to enable
628	  SysRq on a serial console.
629
630	  If unsure, leave an empty string and the option will not be enabled.
631
632config DEBUG_FS
633	bool "Debug Filesystem"
634	help
635	  debugfs is a virtual file system that kernel developers use to put
636	  debugging files into.  Enable this option to be able to read and
637	  write to these files.
638
639	  For detailed documentation on the debugfs API, see
640	  Documentation/filesystems/.
641
642	  If unsure, say N.
643
644choice
645	prompt "Debugfs default access"
646	depends on DEBUG_FS
647	default DEBUG_FS_ALLOW_ALL
648	help
649	  This selects the default access restrictions for debugfs.
650	  It can be overridden with kernel command line option
651	  debugfs=[on,no-mount,off]. The restrictions apply for API access
652	  and filesystem registration.
653
654config DEBUG_FS_ALLOW_ALL
655	bool "Access normal"
656	help
657	  No restrictions apply. Both API and filesystem registration
658	  is on. This is the normal default operation.
659
660config DEBUG_FS_DISALLOW_MOUNT
661	bool "Do not register debugfs as filesystem"
662	help
663	  The API is open but filesystem is not loaded. Clients can still do
664	  their work and read with debug tools that do not need
665	  debugfs filesystem.
666
667config DEBUG_FS_ALLOW_NONE
668	bool "No access"
669	help
670	  Access is off. Clients get -PERM when trying to create nodes in
671	  debugfs tree and debugfs is not registered as a filesystem.
672	  Client can then back-off or continue without debugfs access.
673
674endchoice
675
676source "lib/Kconfig.kgdb"
677source "lib/Kconfig.ubsan"
678source "lib/Kconfig.kcsan"
679
680endmenu
681
682menu "Networking Debugging"
683
684source "net/Kconfig.debug"
685
686endmenu # "Networking Debugging"
687
688menu "Memory Debugging"
689
690source "mm/Kconfig.debug"
691
692config DEBUG_OBJECTS
693	bool "Debug object operations"
694	depends on DEBUG_KERNEL
695	help
696	  If you say Y here, additional code will be inserted into the
697	  kernel to track the life time of various objects and validate
698	  the operations on those objects.
699
700config DEBUG_OBJECTS_SELFTEST
701	bool "Debug objects selftest"
702	depends on DEBUG_OBJECTS
703	help
704	  This enables the selftest of the object debug code.
705
706config DEBUG_OBJECTS_FREE
707	bool "Debug objects in freed memory"
708	depends on DEBUG_OBJECTS
709	help
710	  This enables checks whether a k/v free operation frees an area
711	  which contains an object which has not been deactivated
712	  properly. This can make kmalloc/kfree-intensive workloads
713	  much slower.
714
715config DEBUG_OBJECTS_TIMERS
716	bool "Debug timer objects"
717	depends on DEBUG_OBJECTS
718	help
719	  If you say Y here, additional code will be inserted into the
720	  timer routines to track the life time of timer objects and
721	  validate the timer operations.
722
723config DEBUG_OBJECTS_WORK
724	bool "Debug work objects"
725	depends on DEBUG_OBJECTS
726	help
727	  If you say Y here, additional code will be inserted into the
728	  work queue routines to track the life time of work objects and
729	  validate the work operations.
730
731config DEBUG_OBJECTS_RCU_HEAD
732	bool "Debug RCU callbacks objects"
733	depends on DEBUG_OBJECTS
734	help
735	  Enable this to turn on debugging of RCU list heads (call_rcu() usage).
736
737config DEBUG_OBJECTS_PERCPU_COUNTER
738	bool "Debug percpu counter objects"
739	depends on DEBUG_OBJECTS
740	help
741	  If you say Y here, additional code will be inserted into the
742	  percpu counter routines to track the life time of percpu counter
743	  objects and validate the percpu counter operations.
744
745config DEBUG_OBJECTS_ENABLE_DEFAULT
746	int "debug_objects bootup default value (0-1)"
747	range 0 1
748	default "1"
749	depends on DEBUG_OBJECTS
750	help
751	  Debug objects boot parameter default value
752
753config SHRINKER_DEBUG
754	bool "Enable shrinker debugging support"
755	depends on DEBUG_FS
756	help
757	  Say Y to enable the shrinker debugfs interface which provides
758	  visibility into the kernel memory shrinkers subsystem.
759	  Disable it to avoid an extra memory footprint.
760
761config DEBUG_STACK_USAGE
762	bool "Stack utilization instrumentation"
763	depends on DEBUG_KERNEL && !IA64
764	help
765	  Enables the display of the minimum amount of free stack which each
766	  task has ever had available in the sysrq-T and sysrq-P debug output.
767
768	  This option will slow down process creation somewhat.
769
770config SCHED_STACK_END_CHECK
771	bool "Detect stack corruption on calls to schedule()"
772	depends on DEBUG_KERNEL
773	default n
774	help
775	  This option checks for a stack overrun on calls to schedule().
776	  If the stack end location is found to be over written always panic as
777	  the content of the corrupted region can no longer be trusted.
778	  This is to ensure no erroneous behaviour occurs which could result in
779	  data corruption or a sporadic crash at a later stage once the region
780	  is examined. The runtime overhead introduced is minimal.
781
782config ARCH_HAS_DEBUG_VM_PGTABLE
783	bool
784	help
785	  An architecture should select this when it can successfully
786	  build and run DEBUG_VM_PGTABLE.
787
788config DEBUG_VM_IRQSOFF
789	def_bool DEBUG_VM && !PREEMPT_RT
790
791config DEBUG_VM
792	bool "Debug VM"
793	depends on DEBUG_KERNEL
794	help
795	  Enable this to turn on extended checks in the virtual-memory system
796	  that may impact performance.
797
798	  If unsure, say N.
799
800config DEBUG_VM_SHOOT_LAZIES
801	bool "Debug MMU_LAZY_TLB_SHOOTDOWN implementation"
802	depends on DEBUG_VM
803	depends on MMU_LAZY_TLB_SHOOTDOWN
804	help
805	  Enable additional IPIs that ensure lazy tlb mm references are removed
806	  before the mm is freed.
807
808	  If unsure, say N.
809
810config DEBUG_VM_MAPLE_TREE
811	bool "Debug VM maple trees"
812	depends on DEBUG_VM
813	select DEBUG_MAPLE_TREE
814	help
815	  Enable VM maple tree debugging information and extra validations.
816
817	  If unsure, say N.
818
819config DEBUG_VM_RB
820	bool "Debug VM red-black trees"
821	depends on DEBUG_VM
822	help
823	  Enable VM red-black tree debugging information and extra validations.
824
825	  If unsure, say N.
826
827config DEBUG_VM_PGFLAGS
828	bool "Debug page-flags operations"
829	depends on DEBUG_VM
830	help
831	  Enables extra validation on page flags operations.
832
833	  If unsure, say N.
834
835config DEBUG_VM_PGTABLE
836	bool "Debug arch page table for semantics compliance"
837	depends on MMU
838	depends on ARCH_HAS_DEBUG_VM_PGTABLE
839	default y if DEBUG_VM
840	help
841	  This option provides a debug method which can be used to test
842	  architecture page table helper functions on various platforms in
843	  verifying if they comply with expected generic MM semantics. This
844	  will help architecture code in making sure that any changes or
845	  new additions of these helpers still conform to expected
846	  semantics of the generic MM. Platforms will have to opt in for
847	  this through ARCH_HAS_DEBUG_VM_PGTABLE.
848
849	  If unsure, say N.
850
851config ARCH_HAS_DEBUG_VIRTUAL
852	bool
853
854config DEBUG_VIRTUAL
855	bool "Debug VM translations"
856	depends on DEBUG_KERNEL && ARCH_HAS_DEBUG_VIRTUAL
857	help
858	  Enable some costly sanity checks in virtual to page code. This can
859	  catch mistakes with virt_to_page() and friends.
860
861	  If unsure, say N.
862
863config DEBUG_NOMMU_REGIONS
864	bool "Debug the global anon/private NOMMU mapping region tree"
865	depends on DEBUG_KERNEL && !MMU
866	help
867	  This option causes the global tree of anonymous and private mapping
868	  regions to be regularly checked for invalid topology.
869
870config DEBUG_MEMORY_INIT
871	bool "Debug memory initialisation" if EXPERT
872	default !EXPERT
873	help
874	  Enable this for additional checks during memory initialisation.
875	  The sanity checks verify aspects of the VM such as the memory model
876	  and other information provided by the architecture. Verbose
877	  information will be printed at KERN_DEBUG loglevel depending
878	  on the mminit_loglevel= command-line option.
879
880	  If unsure, say Y
881
882config MEMORY_NOTIFIER_ERROR_INJECT
883	tristate "Memory hotplug notifier error injection module"
884	depends on MEMORY_HOTPLUG && NOTIFIER_ERROR_INJECTION
885	help
886	  This option provides the ability to inject artificial errors to
887	  memory hotplug notifier chain callbacks.  It is controlled through
888	  debugfs interface under /sys/kernel/debug/notifier-error-inject/memory
889
890	  If the notifier call chain should be failed with some events
891	  notified, write the error code to "actions/<notifier event>/error".
892
893	  Example: Inject memory hotplug offline error (-12 == -ENOMEM)
894
895	  # cd /sys/kernel/debug/notifier-error-inject/memory
896	  # echo -12 > actions/MEM_GOING_OFFLINE/error
897	  # echo offline > /sys/devices/system/memory/memoryXXX/state
898	  bash: echo: write error: Cannot allocate memory
899
900	  To compile this code as a module, choose M here: the module will
901	  be called memory-notifier-error-inject.
902
903	  If unsure, say N.
904
905config DEBUG_PER_CPU_MAPS
906	bool "Debug access to per_cpu maps"
907	depends on DEBUG_KERNEL
908	depends on SMP
909	help
910	  Say Y to verify that the per_cpu map being accessed has
911	  been set up. This adds a fair amount of code to kernel memory
912	  and decreases performance.
913
914	  Say N if unsure.
915
916config DEBUG_KMAP_LOCAL
917	bool "Debug kmap_local temporary mappings"
918	depends on DEBUG_KERNEL && KMAP_LOCAL
919	help
920	  This option enables additional error checking for the kmap_local
921	  infrastructure.  Disable for production use.
922
923config ARCH_SUPPORTS_KMAP_LOCAL_FORCE_MAP
924	bool
925
926config DEBUG_KMAP_LOCAL_FORCE_MAP
927	bool "Enforce kmap_local temporary mappings"
928	depends on DEBUG_KERNEL && ARCH_SUPPORTS_KMAP_LOCAL_FORCE_MAP
929	select KMAP_LOCAL
930	select DEBUG_KMAP_LOCAL
931	help
932	  This option enforces temporary mappings through the kmap_local
933	  mechanism for non-highmem pages and on non-highmem systems.
934	  Disable this for production systems!
935
936config DEBUG_HIGHMEM
937	bool "Highmem debugging"
938	depends on DEBUG_KERNEL && HIGHMEM
939	select DEBUG_KMAP_LOCAL_FORCE_MAP if ARCH_SUPPORTS_KMAP_LOCAL_FORCE_MAP
940	select DEBUG_KMAP_LOCAL
941	help
942	  This option enables additional error checking for high memory
943	  systems.  Disable for production systems.
944
945config HAVE_DEBUG_STACKOVERFLOW
946	bool
947
948config DEBUG_STACKOVERFLOW
949	bool "Check for stack overflows"
950	depends on DEBUG_KERNEL && HAVE_DEBUG_STACKOVERFLOW
951	help
952	  Say Y here if you want to check for overflows of kernel, IRQ
953	  and exception stacks (if your architecture uses them). This
954	  option will show detailed messages if free stack space drops
955	  below a certain limit.
956
957	  These kinds of bugs usually occur when call-chains in the
958	  kernel get too deep, especially when interrupts are
959	  involved.
960
961	  Use this in cases where you see apparently random memory
962	  corruption, especially if it appears in 'struct thread_info'
963
964	  If in doubt, say "N".
965
966source "lib/Kconfig.kasan"
967source "lib/Kconfig.kfence"
968source "lib/Kconfig.kmsan"
969
970endmenu # "Memory Debugging"
971
972config DEBUG_SHIRQ
973	bool "Debug shared IRQ handlers"
974	depends on DEBUG_KERNEL
975	help
976	  Enable this to generate a spurious interrupt just before a shared
977	  interrupt handler is deregistered (generating one when registering
978	  is currently disabled). Drivers need to handle this correctly. Some
979	  don't and need to be caught.
980
981menu "Debug Oops, Lockups and Hangs"
982
983config PANIC_ON_OOPS
984	bool "Panic on Oops"
985	help
986	  Say Y here to enable the kernel to panic when it oopses. This
987	  has the same effect as setting oops=panic on the kernel command
988	  line.
989
990	  This feature is useful to ensure that the kernel does not do
991	  anything erroneous after an oops which could result in data
992	  corruption or other issues.
993
994	  Say N if unsure.
995
996config PANIC_ON_OOPS_VALUE
997	int
998	range 0 1
999	default 0 if !PANIC_ON_OOPS
1000	default 1 if PANIC_ON_OOPS
1001
1002config PANIC_TIMEOUT
1003	int "panic timeout"
1004	default 0
1005	help
1006	  Set the timeout value (in seconds) until a reboot occurs when
1007	  the kernel panics. If n = 0, then we wait forever. A timeout
1008	  value n > 0 will wait n seconds before rebooting, while a timeout
1009	  value n < 0 will reboot immediately.
1010
1011config LOCKUP_DETECTOR
1012	bool
1013
1014config SOFTLOCKUP_DETECTOR
1015	bool "Detect Soft Lockups"
1016	depends on DEBUG_KERNEL && !S390
1017	select LOCKUP_DETECTOR
1018	help
1019	  Say Y here to enable the kernel to act as a watchdog to detect
1020	  soft lockups.
1021
1022	  Softlockups are bugs that cause the kernel to loop in kernel
1023	  mode for more than 20 seconds, without giving other tasks a
1024	  chance to run.  The current stack trace is displayed upon
1025	  detection and the system will stay locked up.
1026
1027config BOOTPARAM_SOFTLOCKUP_PANIC
1028	bool "Panic (Reboot) On Soft Lockups"
1029	depends on SOFTLOCKUP_DETECTOR
1030	help
1031	  Say Y here to enable the kernel to panic on "soft lockups",
1032	  which are bugs that cause the kernel to loop in kernel
1033	  mode for more than 20 seconds (configurable using the watchdog_thresh
1034	  sysctl), without giving other tasks a chance to run.
1035
1036	  The panic can be used in combination with panic_timeout,
1037	  to cause the system to reboot automatically after a
1038	  lockup has been detected. This feature is useful for
1039	  high-availability systems that have uptime guarantees and
1040	  where a lockup must be resolved ASAP.
1041
1042	  Say N if unsure.
1043
1044config HAVE_HARDLOCKUP_DETECTOR_BUDDY
1045	bool
1046	depends on SMP
1047	default y
1048
1049#
1050# Global switch whether to build a hardlockup detector at all. It is available
1051# only when the architecture supports at least one implementation. There are
1052# two exceptions. The hardlockup detector is never enabled on:
1053#
1054#	s390: it reported many false positives there
1055#
1056#	sparc64: has a custom implementation which is not using the common
1057#		hardlockup command line options and sysctl interface.
1058#
1059config HARDLOCKUP_DETECTOR
1060	bool "Detect Hard Lockups"
1061	depends on DEBUG_KERNEL && !S390 && !HARDLOCKUP_DETECTOR_SPARC64
1062	depends on HAVE_HARDLOCKUP_DETECTOR_PERF || HAVE_HARDLOCKUP_DETECTOR_BUDDY || HAVE_HARDLOCKUP_DETECTOR_ARCH
1063	imply HARDLOCKUP_DETECTOR_PERF
1064	imply HARDLOCKUP_DETECTOR_BUDDY
1065	imply HARDLOCKUP_DETECTOR_ARCH
1066	select LOCKUP_DETECTOR
1067
1068	help
1069	  Say Y here to enable the kernel to act as a watchdog to detect
1070	  hard lockups.
1071
1072	  Hardlockups are bugs that cause the CPU to loop in kernel mode
1073	  for more than 10 seconds, without letting other interrupts have a
1074	  chance to run.  The current stack trace is displayed upon detection
1075	  and the system will stay locked up.
1076
1077#
1078# Note that arch-specific variants are always preferred.
1079#
1080config HARDLOCKUP_DETECTOR_PREFER_BUDDY
1081	bool "Prefer the buddy CPU hardlockup detector"
1082	depends on HARDLOCKUP_DETECTOR
1083	depends on HAVE_HARDLOCKUP_DETECTOR_PERF && HAVE_HARDLOCKUP_DETECTOR_BUDDY
1084	depends on !HAVE_HARDLOCKUP_DETECTOR_ARCH
1085	help
1086	  Say Y here to prefer the buddy hardlockup detector over the perf one.
1087
1088	  With the buddy detector, each CPU uses its softlockup hrtimer
1089	  to check that the next CPU is processing hrtimer interrupts by
1090	  verifying that a counter is increasing.
1091
1092	  This hardlockup detector is useful on systems that don't have
1093	  an arch-specific hardlockup detector or if resources needed
1094	  for the hardlockup detector are better used for other things.
1095
1096config HARDLOCKUP_DETECTOR_PERF
1097	bool
1098	depends on HARDLOCKUP_DETECTOR
1099	depends on HAVE_HARDLOCKUP_DETECTOR_PERF && !HARDLOCKUP_DETECTOR_PREFER_BUDDY
1100	depends on !HAVE_HARDLOCKUP_DETECTOR_ARCH
1101	select HARDLOCKUP_DETECTOR_COUNTS_HRTIMER
1102
1103config HARDLOCKUP_DETECTOR_BUDDY
1104	bool
1105	depends on HARDLOCKUP_DETECTOR
1106	depends on HAVE_HARDLOCKUP_DETECTOR_BUDDY
1107	depends on !HAVE_HARDLOCKUP_DETECTOR_PERF || HARDLOCKUP_DETECTOR_PREFER_BUDDY
1108	depends on !HAVE_HARDLOCKUP_DETECTOR_ARCH
1109	select HARDLOCKUP_DETECTOR_COUNTS_HRTIMER
1110
1111config HARDLOCKUP_DETECTOR_ARCH
1112	bool
1113	depends on HARDLOCKUP_DETECTOR
1114	depends on HAVE_HARDLOCKUP_DETECTOR_ARCH
1115	help
1116	  The arch-specific implementation of the hardlockup detector will
1117	  be used.
1118
1119#
1120# Both the "perf" and "buddy" hardlockup detectors count hrtimer
1121# interrupts. This config enables functions managing this common code.
1122#
1123config HARDLOCKUP_DETECTOR_COUNTS_HRTIMER
1124	bool
1125	select SOFTLOCKUP_DETECTOR
1126
1127#
1128# Enables a timestamp based low pass filter to compensate for perf based
1129# hard lockup detection which runs too fast due to turbo modes.
1130#
1131config HARDLOCKUP_CHECK_TIMESTAMP
1132	bool
1133
1134config BOOTPARAM_HARDLOCKUP_PANIC
1135	bool "Panic (Reboot) On Hard Lockups"
1136	depends on HARDLOCKUP_DETECTOR
1137	help
1138	  Say Y here to enable the kernel to panic on "hard lockups",
1139	  which are bugs that cause the kernel to loop in kernel
1140	  mode with interrupts disabled for more than 10 seconds (configurable
1141	  using the watchdog_thresh sysctl).
1142
1143	  Say N if unsure.
1144
1145config DETECT_HUNG_TASK
1146	bool "Detect Hung Tasks"
1147	depends on DEBUG_KERNEL
1148	default SOFTLOCKUP_DETECTOR
1149	help
1150	  Say Y here to enable the kernel to detect "hung tasks",
1151	  which are bugs that cause the task to be stuck in
1152	  uninterruptible "D" state indefinitely.
1153
1154	  When a hung task is detected, the kernel will print the
1155	  current stack trace (which you should report), but the
1156	  task will stay in uninterruptible state. If lockdep is
1157	  enabled then all held locks will also be reported. This
1158	  feature has negligible overhead.
1159
1160config DEFAULT_HUNG_TASK_TIMEOUT
1161	int "Default timeout for hung task detection (in seconds)"
1162	depends on DETECT_HUNG_TASK
1163	default 120
1164	help
1165	  This option controls the default timeout (in seconds) used
1166	  to determine when a task has become non-responsive and should
1167	  be considered hung.
1168
1169	  It can be adjusted at runtime via the kernel.hung_task_timeout_secs
1170	  sysctl or by writing a value to
1171	  /proc/sys/kernel/hung_task_timeout_secs.
1172
1173	  A timeout of 0 disables the check.  The default is two minutes.
1174	  Keeping the default should be fine in most cases.
1175
1176config BOOTPARAM_HUNG_TASK_PANIC
1177	bool "Panic (Reboot) On Hung Tasks"
1178	depends on DETECT_HUNG_TASK
1179	help
1180	  Say Y here to enable the kernel to panic on "hung tasks",
1181	  which are bugs that cause the kernel to leave a task stuck
1182	  in uninterruptible "D" state.
1183
1184	  The panic can be used in combination with panic_timeout,
1185	  to cause the system to reboot automatically after a
1186	  hung task has been detected. This feature is useful for
1187	  high-availability systems that have uptime guarantees and
1188	  where a hung tasks must be resolved ASAP.
1189
1190	  Say N if unsure.
1191
1192config BOOTPARAM_HUNG_TASK_PANIC_VALUE
1193	int
1194	depends on DETECT_HUNG_TASK
1195	range 0 1
1196	default 0 if !BOOTPARAM_HUNG_TASK_PANIC
1197	default 1 if BOOTPARAM_HUNG_TASK_PANIC
1198
1199config WQ_WATCHDOG
1200	bool "Detect Workqueue Stalls"
1201	depends on DEBUG_KERNEL
1202	help
1203	  Say Y here to enable stall detection on workqueues.  If a
1204	  worker pool doesn't make forward progress on a pending work
1205	  item for over a given amount of time, 30s by default, a
1206	  warning message is printed along with dump of workqueue
1207	  state.  This can be configured through kernel parameter
1208	  "workqueue.watchdog_thresh" and its sysfs counterpart.
1209
1210config WQ_CPU_INTENSIVE_REPORT
1211	bool "Report per-cpu work items which hog CPU for too long"
1212	depends on DEBUG_KERNEL
1213	help
1214	  Say Y here to enable reporting of concurrency-managed per-cpu work
1215	  items that hog CPUs for longer than
1216	  workqueue.cpu_intensive_thresh_us. Workqueue automatically
1217	  detects and excludes them from concurrency management to prevent
1218	  them from stalling other per-cpu work items. Occassional
1219	  triggering may not necessarily indicate a problem. Repeated
1220	  triggering likely indicates that the work item should be switched
1221	  to use an unbound workqueue.
1222
1223config TEST_LOCKUP
1224	tristate "Test module to generate lockups"
1225	depends on m
1226	help
1227	  This builds the "test_lockup" module that helps to make sure
1228	  that watchdogs and lockup detectors are working properly.
1229
1230	  Depending on module parameters it could emulate soft or hard
1231	  lockup, "hung task", or locking arbitrary lock for a long time.
1232	  Also it could generate series of lockups with cooling-down periods.
1233
1234	  If unsure, say N.
1235
1236endmenu # "Debug lockups and hangs"
1237
1238menu "Scheduler Debugging"
1239
1240config SCHED_DEBUG
1241	bool "Collect scheduler debugging info"
1242	depends on DEBUG_KERNEL && DEBUG_FS
1243	default y
1244	help
1245	  If you say Y here, the /sys/kernel/debug/sched file will be provided
1246	  that can help debug the scheduler. The runtime overhead of this
1247	  option is minimal.
1248
1249config SCHED_INFO
1250	bool
1251	default n
1252
1253config SCHEDSTATS
1254	bool "Collect scheduler statistics"
1255	depends on DEBUG_KERNEL && PROC_FS
1256	select SCHED_INFO
1257	help
1258	  If you say Y here, additional code will be inserted into the
1259	  scheduler and related routines to collect statistics about
1260	  scheduler behavior and provide them in /proc/schedstat.  These
1261	  stats may be useful for both tuning and debugging the scheduler
1262	  If you aren't debugging the scheduler or trying to tune a specific
1263	  application, you can say N to avoid the very slight overhead
1264	  this adds.
1265
1266endmenu
1267
1268config DEBUG_TIMEKEEPING
1269	bool "Enable extra timekeeping sanity checking"
1270	help
1271	  This option will enable additional timekeeping sanity checks
1272	  which may be helpful when diagnosing issues where timekeeping
1273	  problems are suspected.
1274
1275	  This may include checks in the timekeeping hotpaths, so this
1276	  option may have a (very small) performance impact to some
1277	  workloads.
1278
1279	  If unsure, say N.
1280
1281config DEBUG_PREEMPT
1282	bool "Debug preemptible kernel"
1283	depends on DEBUG_KERNEL && PREEMPTION && TRACE_IRQFLAGS_SUPPORT
1284	help
1285	  If you say Y here then the kernel will use a debug variant of the
1286	  commonly used smp_processor_id() function and will print warnings
1287	  if kernel code uses it in a preemption-unsafe way. Also, the kernel
1288	  will detect preemption count underflows.
1289
1290	  This option has potential to introduce high runtime overhead,
1291	  depending on workload as it triggers debugging routines for each
1292	  this_cpu operation. It should only be used for debugging purposes.
1293
1294menu "Lock Debugging (spinlocks, mutexes, etc...)"
1295
1296config LOCK_DEBUGGING_SUPPORT
1297	bool
1298	depends on TRACE_IRQFLAGS_SUPPORT && STACKTRACE_SUPPORT && LOCKDEP_SUPPORT
1299	default y
1300
1301config PROVE_LOCKING
1302	bool "Lock debugging: prove locking correctness"
1303	depends on DEBUG_KERNEL && LOCK_DEBUGGING_SUPPORT
1304	select LOCKDEP
1305	select DEBUG_SPINLOCK
1306	select DEBUG_MUTEXES if !PREEMPT_RT
1307	select DEBUG_RT_MUTEXES if RT_MUTEXES
1308	select DEBUG_RWSEMS
1309	select DEBUG_WW_MUTEX_SLOWPATH
1310	select DEBUG_LOCK_ALLOC
1311	select PREEMPT_COUNT if !ARCH_NO_PREEMPT
1312	select TRACE_IRQFLAGS
1313	default n
1314	help
1315	 This feature enables the kernel to prove that all locking
1316	 that occurs in the kernel runtime is mathematically
1317	 correct: that under no circumstance could an arbitrary (and
1318	 not yet triggered) combination of observed locking
1319	 sequences (on an arbitrary number of CPUs, running an
1320	 arbitrary number of tasks and interrupt contexts) cause a
1321	 deadlock.
1322
1323	 In short, this feature enables the kernel to report locking
1324	 related deadlocks before they actually occur.
1325
1326	 The proof does not depend on how hard and complex a
1327	 deadlock scenario would be to trigger: how many
1328	 participant CPUs, tasks and irq-contexts would be needed
1329	 for it to trigger. The proof also does not depend on
1330	 timing: if a race and a resulting deadlock is possible
1331	 theoretically (no matter how unlikely the race scenario
1332	 is), it will be proven so and will immediately be
1333	 reported by the kernel (once the event is observed that
1334	 makes the deadlock theoretically possible).
1335
1336	 If a deadlock is impossible (i.e. the locking rules, as
1337	 observed by the kernel, are mathematically correct), the
1338	 kernel reports nothing.
1339
1340	 NOTE: this feature can also be enabled for rwlocks, mutexes
1341	 and rwsems - in which case all dependencies between these
1342	 different locking variants are observed and mapped too, and
1343	 the proof of observed correctness is also maintained for an
1344	 arbitrary combination of these separate locking variants.
1345
1346	 For more details, see Documentation/locking/lockdep-design.rst.
1347
1348config PROVE_RAW_LOCK_NESTING
1349	bool "Enable raw_spinlock - spinlock nesting checks"
1350	depends on PROVE_LOCKING
1351	default n
1352	help
1353	 Enable the raw_spinlock vs. spinlock nesting checks which ensure
1354	 that the lock nesting rules for PREEMPT_RT enabled kernels are
1355	 not violated.
1356
1357	 NOTE: There are known nesting problems. So if you enable this
1358	 option expect lockdep splats until these problems have been fully
1359	 addressed which is work in progress. This config switch allows to
1360	 identify and analyze these problems. It will be removed and the
1361	 check permanently enabled once the main issues have been fixed.
1362
1363	 If unsure, select N.
1364
1365config LOCK_STAT
1366	bool "Lock usage statistics"
1367	depends on DEBUG_KERNEL && LOCK_DEBUGGING_SUPPORT
1368	select LOCKDEP
1369	select DEBUG_SPINLOCK
1370	select DEBUG_MUTEXES if !PREEMPT_RT
1371	select DEBUG_RT_MUTEXES if RT_MUTEXES
1372	select DEBUG_LOCK_ALLOC
1373	default n
1374	help
1375	 This feature enables tracking lock contention points
1376
1377	 For more details, see Documentation/locking/lockstat.rst
1378
1379	 This also enables lock events required by "perf lock",
1380	 subcommand of perf.
1381	 If you want to use "perf lock", you also need to turn on
1382	 CONFIG_EVENT_TRACING.
1383
1384	 CONFIG_LOCK_STAT defines "contended" and "acquired" lock events.
1385	 (CONFIG_LOCKDEP defines "acquire" and "release" events.)
1386
1387config DEBUG_RT_MUTEXES
1388	bool "RT Mutex debugging, deadlock detection"
1389	depends on DEBUG_KERNEL && RT_MUTEXES
1390	help
1391	 This allows rt mutex semantics violations and rt mutex related
1392	 deadlocks (lockups) to be detected and reported automatically.
1393
1394config DEBUG_SPINLOCK
1395	bool "Spinlock and rw-lock debugging: basic checks"
1396	depends on DEBUG_KERNEL
1397	select UNINLINE_SPIN_UNLOCK
1398	help
1399	  Say Y here and build SMP to catch missing spinlock initialization
1400	  and certain other kinds of spinlock errors commonly made.  This is
1401	  best used in conjunction with the NMI watchdog so that spinlock
1402	  deadlocks are also debuggable.
1403
1404config DEBUG_MUTEXES
1405	bool "Mutex debugging: basic checks"
1406	depends on DEBUG_KERNEL && !PREEMPT_RT
1407	help
1408	 This feature allows mutex semantics violations to be detected and
1409	 reported.
1410
1411config DEBUG_WW_MUTEX_SLOWPATH
1412	bool "Wait/wound mutex debugging: Slowpath testing"
1413	depends on DEBUG_KERNEL && LOCK_DEBUGGING_SUPPORT
1414	select DEBUG_LOCK_ALLOC
1415	select DEBUG_SPINLOCK
1416	select DEBUG_MUTEXES if !PREEMPT_RT
1417	select DEBUG_RT_MUTEXES if PREEMPT_RT
1418	help
1419	 This feature enables slowpath testing for w/w mutex users by
1420	 injecting additional -EDEADLK wound/backoff cases. Together with
1421	 the full mutex checks enabled with (CONFIG_PROVE_LOCKING) this
1422	 will test all possible w/w mutex interface abuse with the
1423	 exception of simply not acquiring all the required locks.
1424	 Note that this feature can introduce significant overhead, so
1425	 it really should not be enabled in a production or distro kernel,
1426	 even a debug kernel.  If you are a driver writer, enable it.  If
1427	 you are a distro, do not.
1428
1429config DEBUG_RWSEMS
1430	bool "RW Semaphore debugging: basic checks"
1431	depends on DEBUG_KERNEL
1432	help
1433	  This debugging feature allows mismatched rw semaphore locks
1434	  and unlocks to be detected and reported.
1435
1436config DEBUG_LOCK_ALLOC
1437	bool "Lock debugging: detect incorrect freeing of live locks"
1438	depends on DEBUG_KERNEL && LOCK_DEBUGGING_SUPPORT
1439	select DEBUG_SPINLOCK
1440	select DEBUG_MUTEXES if !PREEMPT_RT
1441	select DEBUG_RT_MUTEXES if RT_MUTEXES
1442	select LOCKDEP
1443	help
1444	 This feature will check whether any held lock (spinlock, rwlock,
1445	 mutex or rwsem) is incorrectly freed by the kernel, via any of the
1446	 memory-freeing routines (kfree(), kmem_cache_free(), free_pages(),
1447	 vfree(), etc.), whether a live lock is incorrectly reinitialized via
1448	 spin_lock_init()/mutex_init()/etc., or whether there is any lock
1449	 held during task exit.
1450
1451config LOCKDEP
1452	bool
1453	depends on DEBUG_KERNEL && LOCK_DEBUGGING_SUPPORT
1454	select STACKTRACE
1455	select KALLSYMS
1456	select KALLSYMS_ALL
1457
1458config LOCKDEP_SMALL
1459	bool
1460
1461config LOCKDEP_BITS
1462	int "Bitsize for MAX_LOCKDEP_ENTRIES"
1463	depends on LOCKDEP && !LOCKDEP_SMALL
1464	range 10 24
1465	default 15
1466	help
1467	  Try increasing this value if you hit "BUG: MAX_LOCKDEP_ENTRIES too low!" message.
1468
1469config LOCKDEP_CHAINS_BITS
1470	int "Bitsize for MAX_LOCKDEP_CHAINS"
1471	depends on LOCKDEP && !LOCKDEP_SMALL
1472	range 10 30
1473	default 16
1474	help
1475	  Try increasing this value if you hit "BUG: MAX_LOCKDEP_CHAINS too low!" message.
1476
1477config LOCKDEP_STACK_TRACE_BITS
1478	int "Bitsize for MAX_STACK_TRACE_ENTRIES"
1479	depends on LOCKDEP && !LOCKDEP_SMALL
1480	range 10 26
1481	default 19
1482	help
1483	  Try increasing this value if you hit "BUG: MAX_STACK_TRACE_ENTRIES too low!" message.
1484
1485config LOCKDEP_STACK_TRACE_HASH_BITS
1486	int "Bitsize for STACK_TRACE_HASH_SIZE"
1487	depends on LOCKDEP && !LOCKDEP_SMALL
1488	range 10 26
1489	default 14
1490	help
1491	  Try increasing this value if you need large STACK_TRACE_HASH_SIZE.
1492
1493config LOCKDEP_CIRCULAR_QUEUE_BITS
1494	int "Bitsize for elements in circular_queue struct"
1495	depends on LOCKDEP
1496	range 10 26
1497	default 12
1498	help
1499	  Try increasing this value if you hit "lockdep bfs error:-1" warning due to __cq_enqueue() failure.
1500
1501config DEBUG_LOCKDEP
1502	bool "Lock dependency engine debugging"
1503	depends on DEBUG_KERNEL && LOCKDEP
1504	select DEBUG_IRQFLAGS
1505	help
1506	  If you say Y here, the lock dependency engine will do
1507	  additional runtime checks to debug itself, at the price
1508	  of more runtime overhead.
1509
1510config DEBUG_ATOMIC_SLEEP
1511	bool "Sleep inside atomic section checking"
1512	select PREEMPT_COUNT
1513	depends on DEBUG_KERNEL
1514	depends on !ARCH_NO_PREEMPT
1515	help
1516	  If you say Y here, various routines which may sleep will become very
1517	  noisy if they are called inside atomic sections: when a spinlock is
1518	  held, inside an rcu read side critical section, inside preempt disabled
1519	  sections, inside an interrupt, etc...
1520
1521config DEBUG_LOCKING_API_SELFTESTS
1522	bool "Locking API boot-time self-tests"
1523	depends on DEBUG_KERNEL
1524	help
1525	  Say Y here if you want the kernel to run a short self-test during
1526	  bootup. The self-test checks whether common types of locking bugs
1527	  are detected by debugging mechanisms or not. (if you disable
1528	  lock debugging then those bugs won't be detected of course.)
1529	  The following locking APIs are covered: spinlocks, rwlocks,
1530	  mutexes and rwsems.
1531
1532config LOCK_TORTURE_TEST
1533	tristate "torture tests for locking"
1534	depends on DEBUG_KERNEL
1535	select TORTURE_TEST
1536	help
1537	  This option provides a kernel module that runs torture tests
1538	  on kernel locking primitives.  The kernel module may be built
1539	  after the fact on the running kernel to be tested, if desired.
1540
1541	  Say Y here if you want kernel locking-primitive torture tests
1542	  to be built into the kernel.
1543	  Say M if you want these torture tests to build as a module.
1544	  Say N if you are unsure.
1545
1546config WW_MUTEX_SELFTEST
1547	tristate "Wait/wound mutex selftests"
1548	help
1549	  This option provides a kernel module that runs tests on the
1550	  on the struct ww_mutex locking API.
1551
1552	  It is recommended to enable DEBUG_WW_MUTEX_SLOWPATH in conjunction
1553	  with this test harness.
1554
1555	  Say M if you want these self tests to build as a module.
1556	  Say N if you are unsure.
1557
1558config SCF_TORTURE_TEST
1559	tristate "torture tests for smp_call_function*()"
1560	depends on DEBUG_KERNEL
1561	select TORTURE_TEST
1562	help
1563	  This option provides a kernel module that runs torture tests
1564	  on the smp_call_function() family of primitives.  The kernel
1565	  module may be built after the fact on the running kernel to
1566	  be tested, if desired.
1567
1568config CSD_LOCK_WAIT_DEBUG
1569	bool "Debugging for csd_lock_wait(), called from smp_call_function*()"
1570	depends on DEBUG_KERNEL
1571	depends on 64BIT
1572	default n
1573	help
1574	  This option enables debug prints when CPUs are slow to respond
1575	  to the smp_call_function*() IPI wrappers.  These debug prints
1576	  include the IPI handler function currently executing (if any)
1577	  and relevant stack traces.
1578
1579config CSD_LOCK_WAIT_DEBUG_DEFAULT
1580	bool "Default csd_lock_wait() debugging on at boot time"
1581	depends on CSD_LOCK_WAIT_DEBUG
1582	depends on 64BIT
1583	default n
1584	help
1585	  This option causes the csdlock_debug= kernel boot parameter to
1586	  default to 1 (basic debugging) instead of 0 (no debugging).
1587
1588endmenu # lock debugging
1589
1590config TRACE_IRQFLAGS
1591	depends on TRACE_IRQFLAGS_SUPPORT
1592	bool
1593	help
1594	  Enables hooks to interrupt enabling and disabling for
1595	  either tracing or lock debugging.
1596
1597config TRACE_IRQFLAGS_NMI
1598	def_bool y
1599	depends on TRACE_IRQFLAGS
1600	depends on TRACE_IRQFLAGS_NMI_SUPPORT
1601
1602config NMI_CHECK_CPU
1603	bool "Debugging for CPUs failing to respond to backtrace requests"
1604	depends on DEBUG_KERNEL
1605	depends on X86
1606	default n
1607	help
1608	  Enables debug prints when a CPU fails to respond to a given
1609	  backtrace NMI.  These prints provide some reasons why a CPU
1610	  might legitimately be failing to respond, for example, if it
1611	  is offline of if ignore_nmis is set.
1612
1613config DEBUG_IRQFLAGS
1614	bool "Debug IRQ flag manipulation"
1615	help
1616	  Enables checks for potentially unsafe enabling or disabling of
1617	  interrupts, such as calling raw_local_irq_restore() when interrupts
1618	  are enabled.
1619
1620config STACKTRACE
1621	bool "Stack backtrace support"
1622	depends on STACKTRACE_SUPPORT
1623	help
1624	  This option causes the kernel to create a /proc/pid/stack for
1625	  every process, showing its current stack trace.
1626	  It is also used by various kernel debugging features that require
1627	  stack trace generation.
1628
1629config WARN_ALL_UNSEEDED_RANDOM
1630	bool "Warn for all uses of unseeded randomness"
1631	default n
1632	help
1633	  Some parts of the kernel contain bugs relating to their use of
1634	  cryptographically secure random numbers before it's actually possible
1635	  to generate those numbers securely. This setting ensures that these
1636	  flaws don't go unnoticed, by enabling a message, should this ever
1637	  occur. This will allow people with obscure setups to know when things
1638	  are going wrong, so that they might contact developers about fixing
1639	  it.
1640
1641	  Unfortunately, on some models of some architectures getting
1642	  a fully seeded CRNG is extremely difficult, and so this can
1643	  result in dmesg getting spammed for a surprisingly long
1644	  time.  This is really bad from a security perspective, and
1645	  so architecture maintainers really need to do what they can
1646	  to get the CRNG seeded sooner after the system is booted.
1647	  However, since users cannot do anything actionable to
1648	  address this, by default this option is disabled.
1649
1650	  Say Y here if you want to receive warnings for all uses of
1651	  unseeded randomness.  This will be of use primarily for
1652	  those developers interested in improving the security of
1653	  Linux kernels running on their architecture (or
1654	  subarchitecture).
1655
1656config DEBUG_KOBJECT
1657	bool "kobject debugging"
1658	depends on DEBUG_KERNEL
1659	help
1660	  If you say Y here, some extra kobject debugging messages will be sent
1661	  to the syslog.
1662
1663config DEBUG_KOBJECT_RELEASE
1664	bool "kobject release debugging"
1665	depends on DEBUG_OBJECTS_TIMERS
1666	help
1667	  kobjects are reference counted objects.  This means that their
1668	  last reference count put is not predictable, and the kobject can
1669	  live on past the point at which a driver decides to drop its
1670	  initial reference to the kobject gained on allocation.  An
1671	  example of this would be a struct device which has just been
1672	  unregistered.
1673
1674	  However, some buggy drivers assume that after such an operation,
1675	  the memory backing the kobject can be immediately freed.  This
1676	  goes completely against the principles of a refcounted object.
1677
1678	  If you say Y here, the kernel will delay the release of kobjects
1679	  on the last reference count to improve the visibility of this
1680	  kind of kobject release bug.
1681
1682config HAVE_DEBUG_BUGVERBOSE
1683	bool
1684
1685menu "Debug kernel data structures"
1686
1687config DEBUG_LIST
1688	bool "Debug linked list manipulation"
1689	depends on DEBUG_KERNEL
1690	select LIST_HARDENED
1691	help
1692	  Enable this to turn on extended checks in the linked-list walking
1693	  routines.
1694
1695	  This option trades better quality error reports for performance, and
1696	  is more suitable for kernel debugging. If you care about performance,
1697	  you should only enable CONFIG_LIST_HARDENED instead.
1698
1699	  If unsure, say N.
1700
1701config DEBUG_PLIST
1702	bool "Debug priority linked list manipulation"
1703	depends on DEBUG_KERNEL
1704	help
1705	  Enable this to turn on extended checks in the priority-ordered
1706	  linked-list (plist) walking routines.  This checks the entire
1707	  list multiple times during each manipulation.
1708
1709	  If unsure, say N.
1710
1711config DEBUG_SG
1712	bool "Debug SG table operations"
1713	depends on DEBUG_KERNEL
1714	help
1715	  Enable this to turn on checks on scatter-gather tables. This can
1716	  help find problems with drivers that do not properly initialize
1717	  their sg tables.
1718
1719	  If unsure, say N.
1720
1721config DEBUG_NOTIFIERS
1722	bool "Debug notifier call chains"
1723	depends on DEBUG_KERNEL
1724	help
1725	  Enable this to turn on sanity checking for notifier call chains.
1726	  This is most useful for kernel developers to make sure that
1727	  modules properly unregister themselves from notifier chains.
1728	  This is a relatively cheap check but if you care about maximum
1729	  performance, say N.
1730
1731config DEBUG_MAPLE_TREE
1732	bool "Debug maple trees"
1733	depends on DEBUG_KERNEL
1734	help
1735	  Enable maple tree debugging information and extra validations.
1736
1737	  If unsure, say N.
1738
1739endmenu
1740
1741source "kernel/rcu/Kconfig.debug"
1742
1743config DEBUG_WQ_FORCE_RR_CPU
1744	bool "Force round-robin CPU selection for unbound work items"
1745	depends on DEBUG_KERNEL
1746	default n
1747	help
1748	  Workqueue used to implicitly guarantee that work items queued
1749	  without explicit CPU specified are put on the local CPU.  This
1750	  guarantee is no longer true and while local CPU is still
1751	  preferred work items may be put on foreign CPUs.  Kernel
1752	  parameter "workqueue.debug_force_rr_cpu" is added to force
1753	  round-robin CPU selection to flush out usages which depend on the
1754	  now broken guarantee.  This config option enables the debug
1755	  feature by default.  When enabled, memory and cache locality will
1756	  be impacted.
1757
1758config CPU_HOTPLUG_STATE_CONTROL
1759	bool "Enable CPU hotplug state control"
1760	depends on DEBUG_KERNEL
1761	depends on HOTPLUG_CPU
1762	default n
1763	help
1764	  Allows to write steps between "offline" and "online" to the CPUs
1765	  sysfs target file so states can be stepped granular. This is a debug
1766	  option for now as the hotplug machinery cannot be stopped and
1767	  restarted at arbitrary points yet.
1768
1769	  Say N if your are unsure.
1770
1771config LATENCYTOP
1772	bool "Latency measuring infrastructure"
1773	depends on DEBUG_KERNEL
1774	depends on STACKTRACE_SUPPORT
1775	depends on PROC_FS
1776	depends on FRAME_POINTER || MIPS || PPC || S390 || MICROBLAZE || ARM || ARC || X86
1777	select KALLSYMS
1778	select KALLSYMS_ALL
1779	select STACKTRACE
1780	select SCHEDSTATS
1781	help
1782	  Enable this option if you want to use the LatencyTOP tool
1783	  to find out which userspace is blocking on what kernel operations.
1784
1785config DEBUG_CGROUP_REF
1786	bool "Disable inlining of cgroup css reference count functions"
1787	depends on DEBUG_KERNEL
1788	depends on CGROUPS
1789	depends on KPROBES
1790	default n
1791	help
1792	  Force cgroup css reference count functions to not be inlined so
1793	  that they can be kprobed for debugging.
1794
1795source "kernel/trace/Kconfig"
1796
1797config PROVIDE_OHCI1394_DMA_INIT
1798	bool "Remote debugging over FireWire early on boot"
1799	depends on PCI && X86
1800	help
1801	  If you want to debug problems which hang or crash the kernel early
1802	  on boot and the crashing machine has a FireWire port, you can use
1803	  this feature to remotely access the memory of the crashed machine
1804	  over FireWire. This employs remote DMA as part of the OHCI1394
1805	  specification which is now the standard for FireWire controllers.
1806
1807	  With remote DMA, you can monitor the printk buffer remotely using
1808	  firescope and access all memory below 4GB using fireproxy from gdb.
1809	  Even controlling a kernel debugger is possible using remote DMA.
1810
1811	  Usage:
1812
1813	  If ohci1394_dma=early is used as boot parameter, it will initialize
1814	  all OHCI1394 controllers which are found in the PCI config space.
1815
1816	  As all changes to the FireWire bus such as enabling and disabling
1817	  devices cause a bus reset and thereby disable remote DMA for all
1818	  devices, be sure to have the cable plugged and FireWire enabled on
1819	  the debugging host before booting the debug target for debugging.
1820
1821	  This code (~1k) is freed after boot. By then, the firewire stack
1822	  in charge of the OHCI-1394 controllers should be used instead.
1823
1824	  See Documentation/core-api/debugging-via-ohci1394.rst for more information.
1825
1826source "samples/Kconfig"
1827
1828config ARCH_HAS_DEVMEM_IS_ALLOWED
1829	bool
1830
1831config STRICT_DEVMEM
1832	bool "Filter access to /dev/mem"
1833	depends on MMU && DEVMEM
1834	depends on ARCH_HAS_DEVMEM_IS_ALLOWED || GENERIC_LIB_DEVMEM_IS_ALLOWED
1835	default y if PPC || X86 || ARM64
1836	help
1837	  If this option is disabled, you allow userspace (root) access to all
1838	  of memory, including kernel and userspace memory. Accidental
1839	  access to this is obviously disastrous, but specific access can
1840	  be used by people debugging the kernel. Note that with PAT support
1841	  enabled, even in this case there are restrictions on /dev/mem
1842	  use due to the cache aliasing requirements.
1843
1844	  If this option is switched on, and IO_STRICT_DEVMEM=n, the /dev/mem
1845	  file only allows userspace access to PCI space and the BIOS code and
1846	  data regions.  This is sufficient for dosemu and X and all common
1847	  users of /dev/mem.
1848
1849	  If in doubt, say Y.
1850
1851config IO_STRICT_DEVMEM
1852	bool "Filter I/O access to /dev/mem"
1853	depends on STRICT_DEVMEM
1854	help
1855	  If this option is disabled, you allow userspace (root) access to all
1856	  io-memory regardless of whether a driver is actively using that
1857	  range.  Accidental access to this is obviously disastrous, but
1858	  specific access can be used by people debugging kernel drivers.
1859
1860	  If this option is switched on, the /dev/mem file only allows
1861	  userspace access to *idle* io-memory ranges (see /proc/iomem) This
1862	  may break traditional users of /dev/mem (dosemu, legacy X, etc...)
1863	  if the driver using a given range cannot be disabled.
1864
1865	  If in doubt, say Y.
1866
1867menu "$(SRCARCH) Debugging"
1868
1869source "arch/$(SRCARCH)/Kconfig.debug"
1870
1871endmenu
1872
1873menu "Kernel Testing and Coverage"
1874
1875source "lib/kunit/Kconfig"
1876
1877config NOTIFIER_ERROR_INJECTION
1878	tristate "Notifier error injection"
1879	depends on DEBUG_KERNEL
1880	select DEBUG_FS
1881	help
1882	  This option provides the ability to inject artificial errors to
1883	  specified notifier chain callbacks. It is useful to test the error
1884	  handling of notifier call chain failures.
1885
1886	  Say N if unsure.
1887
1888config PM_NOTIFIER_ERROR_INJECT
1889	tristate "PM notifier error injection module"
1890	depends on PM && NOTIFIER_ERROR_INJECTION
1891	default m if PM_DEBUG
1892	help
1893	  This option provides the ability to inject artificial errors to
1894	  PM notifier chain callbacks.  It is controlled through debugfs
1895	  interface /sys/kernel/debug/notifier-error-inject/pm
1896
1897	  If the notifier call chain should be failed with some events
1898	  notified, write the error code to "actions/<notifier event>/error".
1899
1900	  Example: Inject PM suspend error (-12 = -ENOMEM)
1901
1902	  # cd /sys/kernel/debug/notifier-error-inject/pm/
1903	  # echo -12 > actions/PM_SUSPEND_PREPARE/error
1904	  # echo mem > /sys/power/state
1905	  bash: echo: write error: Cannot allocate memory
1906
1907	  To compile this code as a module, choose M here: the module will
1908	  be called pm-notifier-error-inject.
1909
1910	  If unsure, say N.
1911
1912config OF_RECONFIG_NOTIFIER_ERROR_INJECT
1913	tristate "OF reconfig notifier error injection module"
1914	depends on OF_DYNAMIC && NOTIFIER_ERROR_INJECTION
1915	help
1916	  This option provides the ability to inject artificial errors to
1917	  OF reconfig notifier chain callbacks.  It is controlled
1918	  through debugfs interface under
1919	  /sys/kernel/debug/notifier-error-inject/OF-reconfig/
1920
1921	  If the notifier call chain should be failed with some events
1922	  notified, write the error code to "actions/<notifier event>/error".
1923
1924	  To compile this code as a module, choose M here: the module will
1925	  be called of-reconfig-notifier-error-inject.
1926
1927	  If unsure, say N.
1928
1929config NETDEV_NOTIFIER_ERROR_INJECT
1930	tristate "Netdev notifier error injection module"
1931	depends on NET && NOTIFIER_ERROR_INJECTION
1932	help
1933	  This option provides the ability to inject artificial errors to
1934	  netdevice notifier chain callbacks.  It is controlled through debugfs
1935	  interface /sys/kernel/debug/notifier-error-inject/netdev
1936
1937	  If the notifier call chain should be failed with some events
1938	  notified, write the error code to "actions/<notifier event>/error".
1939
1940	  Example: Inject netdevice mtu change error (-22 = -EINVAL)
1941
1942	  # cd /sys/kernel/debug/notifier-error-inject/netdev
1943	  # echo -22 > actions/NETDEV_CHANGEMTU/error
1944	  # ip link set eth0 mtu 1024
1945	  RTNETLINK answers: Invalid argument
1946
1947	  To compile this code as a module, choose M here: the module will
1948	  be called netdev-notifier-error-inject.
1949
1950	  If unsure, say N.
1951
1952config FUNCTION_ERROR_INJECTION
1953	bool "Fault-injections of functions"
1954	depends on HAVE_FUNCTION_ERROR_INJECTION && KPROBES
1955	help
1956	  Add fault injections into various functions that are annotated with
1957	  ALLOW_ERROR_INJECTION() in the kernel. BPF may also modify the return
1958	  value of these functions. This is useful to test error paths of code.
1959
1960	  If unsure, say N
1961
1962config FAULT_INJECTION
1963	bool "Fault-injection framework"
1964	depends on DEBUG_KERNEL
1965	help
1966	  Provide fault-injection framework.
1967	  For more details, see Documentation/fault-injection/.
1968
1969config FAILSLAB
1970	bool "Fault-injection capability for kmalloc"
1971	depends on FAULT_INJECTION
1972	depends on SLAB || SLUB
1973	help
1974	  Provide fault-injection capability for kmalloc.
1975
1976config FAIL_PAGE_ALLOC
1977	bool "Fault-injection capability for alloc_pages()"
1978	depends on FAULT_INJECTION
1979	help
1980	  Provide fault-injection capability for alloc_pages().
1981
1982config FAULT_INJECTION_USERCOPY
1983	bool "Fault injection capability for usercopy functions"
1984	depends on FAULT_INJECTION
1985	help
1986	  Provides fault-injection capability to inject failures
1987	  in usercopy functions (copy_from_user(), get_user(), ...).
1988
1989config FAIL_MAKE_REQUEST
1990	bool "Fault-injection capability for disk IO"
1991	depends on FAULT_INJECTION && BLOCK
1992	help
1993	  Provide fault-injection capability for disk IO.
1994
1995config FAIL_IO_TIMEOUT
1996	bool "Fault-injection capability for faking disk interrupts"
1997	depends on FAULT_INJECTION && BLOCK
1998	help
1999	  Provide fault-injection capability on end IO handling. This
2000	  will make the block layer "forget" an interrupt as configured,
2001	  thus exercising the error handling.
2002
2003	  Only works with drivers that use the generic timeout handling,
2004	  for others it won't do anything.
2005
2006config FAIL_FUTEX
2007	bool "Fault-injection capability for futexes"
2008	select DEBUG_FS
2009	depends on FAULT_INJECTION && FUTEX
2010	help
2011	  Provide fault-injection capability for futexes.
2012
2013config FAULT_INJECTION_DEBUG_FS
2014	bool "Debugfs entries for fault-injection capabilities"
2015	depends on FAULT_INJECTION && SYSFS && DEBUG_FS
2016	help
2017	  Enable configuration of fault-injection capabilities via debugfs.
2018
2019config FAIL_FUNCTION
2020	bool "Fault-injection capability for functions"
2021	depends on FAULT_INJECTION_DEBUG_FS && FUNCTION_ERROR_INJECTION
2022	help
2023	  Provide function-based fault-injection capability.
2024	  This will allow you to override a specific function with a return
2025	  with given return value. As a result, function caller will see
2026	  an error value and have to handle it. This is useful to test the
2027	  error handling in various subsystems.
2028
2029config FAIL_MMC_REQUEST
2030	bool "Fault-injection capability for MMC IO"
2031	depends on FAULT_INJECTION_DEBUG_FS && MMC
2032	help
2033	  Provide fault-injection capability for MMC IO.
2034	  This will make the mmc core return data errors. This is
2035	  useful to test the error handling in the mmc block device
2036	  and to test how the mmc host driver handles retries from
2037	  the block device.
2038
2039config FAIL_SUNRPC
2040	bool "Fault-injection capability for SunRPC"
2041	depends on FAULT_INJECTION_DEBUG_FS && SUNRPC_DEBUG
2042	help
2043	  Provide fault-injection capability for SunRPC and
2044	  its consumers.
2045
2046config FAULT_INJECTION_CONFIGFS
2047	bool "Configfs interface for fault-injection capabilities"
2048	depends on FAULT_INJECTION
2049	select CONFIGFS_FS
2050	help
2051	  This option allows configfs-based drivers to dynamically configure
2052	  fault-injection via configfs.  Each parameter for driver-specific
2053	  fault-injection can be made visible as a configfs attribute in a
2054	  configfs group.
2055
2056
2057config FAULT_INJECTION_STACKTRACE_FILTER
2058	bool "stacktrace filter for fault-injection capabilities"
2059	depends on FAULT_INJECTION
2060	depends on (FAULT_INJECTION_DEBUG_FS || FAULT_INJECTION_CONFIGFS) && STACKTRACE_SUPPORT
2061	select STACKTRACE
2062	depends on FRAME_POINTER || MIPS || PPC || S390 || MICROBLAZE || ARM || ARC || X86
2063	help
2064	  Provide stacktrace filter for fault-injection capabilities
2065
2066config ARCH_HAS_KCOV
2067	bool
2068	help
2069	  An architecture should select this when it can successfully
2070	  build and run with CONFIG_KCOV. This typically requires
2071	  disabling instrumentation for some early boot code.
2072
2073config CC_HAS_SANCOV_TRACE_PC
2074	def_bool $(cc-option,-fsanitize-coverage=trace-pc)
2075
2076
2077config KCOV
2078	bool "Code coverage for fuzzing"
2079	depends on ARCH_HAS_KCOV
2080	depends on CC_HAS_SANCOV_TRACE_PC || GCC_PLUGINS
2081	depends on !ARCH_WANTS_NO_INSTR || HAVE_NOINSTR_HACK || \
2082		   GCC_VERSION >= 120000 || CLANG_VERSION >= 130000
2083	select DEBUG_FS
2084	select GCC_PLUGIN_SANCOV if !CC_HAS_SANCOV_TRACE_PC
2085	select OBJTOOL if HAVE_NOINSTR_HACK
2086	help
2087	  KCOV exposes kernel code coverage information in a form suitable
2088	  for coverage-guided fuzzing (randomized testing).
2089
2090	  If RANDOMIZE_BASE is enabled, PC values will not be stable across
2091	  different machines and across reboots. If you need stable PC values,
2092	  disable RANDOMIZE_BASE.
2093
2094	  For more details, see Documentation/dev-tools/kcov.rst.
2095
2096config KCOV_ENABLE_COMPARISONS
2097	bool "Enable comparison operands collection by KCOV"
2098	depends on KCOV
2099	depends on $(cc-option,-fsanitize-coverage=trace-cmp)
2100	help
2101	  KCOV also exposes operands of every comparison in the instrumented
2102	  code along with operand sizes and PCs of the comparison instructions.
2103	  These operands can be used by fuzzing engines to improve the quality
2104	  of fuzzing coverage.
2105
2106config KCOV_INSTRUMENT_ALL
2107	bool "Instrument all code by default"
2108	depends on KCOV
2109	default y
2110	help
2111	  If you are doing generic system call fuzzing (like e.g. syzkaller),
2112	  then you will want to instrument the whole kernel and you should
2113	  say y here. If you are doing more targeted fuzzing (like e.g.
2114	  filesystem fuzzing with AFL) then you will want to enable coverage
2115	  for more specific subsets of files, and should say n here.
2116
2117config KCOV_IRQ_AREA_SIZE
2118	hex "Size of interrupt coverage collection area in words"
2119	depends on KCOV
2120	default 0x40000
2121	help
2122	  KCOV uses preallocated per-cpu areas to collect coverage from
2123	  soft interrupts. This specifies the size of those areas in the
2124	  number of unsigned long words.
2125
2126menuconfig RUNTIME_TESTING_MENU
2127	bool "Runtime Testing"
2128	def_bool y
2129
2130if RUNTIME_TESTING_MENU
2131
2132config TEST_DHRY
2133	tristate "Dhrystone benchmark test"
2134	help
2135	  Enable this to include the Dhrystone 2.1 benchmark.  This test
2136	  calculates the number of Dhrystones per second, and the number of
2137	  DMIPS (Dhrystone MIPS) obtained when the Dhrystone score is divided
2138	  by 1757 (the number of Dhrystones per second obtained on the VAX
2139	  11/780, nominally a 1 MIPS machine).
2140
2141	  To run the benchmark, it needs to be enabled explicitly, either from
2142	  the kernel command line (when built-in), or from userspace (when
2143	  built-in or modular.
2144
2145	  Run once during kernel boot:
2146
2147	      test_dhry.run
2148
2149	  Set number of iterations from kernel command line:
2150
2151	      test_dhry.iterations=<n>
2152
2153	  Set number of iterations from userspace:
2154
2155	      echo <n> > /sys/module/test_dhry/parameters/iterations
2156
2157	  Trigger manual run from userspace:
2158
2159	      echo y > /sys/module/test_dhry/parameters/run
2160
2161	  If the number of iterations is <= 0, the test will devise a suitable
2162	  number of iterations (test runs for at least 2s) automatically.
2163	  This process takes ca. 4s.
2164
2165	  If unsure, say N.
2166
2167config LKDTM
2168	tristate "Linux Kernel Dump Test Tool Module"
2169	depends on DEBUG_FS
2170	help
2171	This module enables testing of the different dumping mechanisms by
2172	inducing system failures at predefined crash points.
2173	If you don't need it: say N
2174	Choose M here to compile this code as a module. The module will be
2175	called lkdtm.
2176
2177	Documentation on how to use the module can be found in
2178	Documentation/fault-injection/provoke-crashes.rst
2179
2180config CPUMASK_KUNIT_TEST
2181	tristate "KUnit test for cpumask" if !KUNIT_ALL_TESTS
2182	depends on KUNIT
2183	default KUNIT_ALL_TESTS
2184	help
2185	  Enable to turn on cpumask tests, running at boot or module load time.
2186
2187	  For more information on KUnit and unit tests in general, please refer
2188	  to the KUnit documentation in Documentation/dev-tools/kunit/.
2189
2190	  If unsure, say N.
2191
2192config TEST_LIST_SORT
2193	tristate "Linked list sorting test" if !KUNIT_ALL_TESTS
2194	depends on KUNIT
2195	default KUNIT_ALL_TESTS
2196	help
2197	  Enable this to turn on 'list_sort()' function test. This test is
2198	  executed only once during system boot (so affects only boot time),
2199	  or at module load time.
2200
2201	  If unsure, say N.
2202
2203config TEST_MIN_HEAP
2204	tristate "Min heap test"
2205	depends on DEBUG_KERNEL || m
2206	help
2207	  Enable this to turn on min heap function tests. This test is
2208	  executed only once during system boot (so affects only boot time),
2209	  or at module load time.
2210
2211	  If unsure, say N.
2212
2213config TEST_SORT
2214	tristate "Array-based sort test" if !KUNIT_ALL_TESTS
2215	depends on KUNIT
2216	default KUNIT_ALL_TESTS
2217	help
2218	  This option enables the self-test function of 'sort()' at boot,
2219	  or at module load time.
2220
2221	  If unsure, say N.
2222
2223config TEST_DIV64
2224	tristate "64bit/32bit division and modulo test"
2225	depends on DEBUG_KERNEL || m
2226	help
2227	  Enable this to turn on 'do_div()' function test. This test is
2228	  executed only once during system boot (so affects only boot time),
2229	  or at module load time.
2230
2231	  If unsure, say N.
2232
2233config TEST_IOV_ITER
2234	tristate "Test iov_iter operation" if !KUNIT_ALL_TESTS
2235	depends on KUNIT
2236	depends on MMU
2237	default KUNIT_ALL_TESTS
2238	help
2239	  Enable this to turn on testing of the operation of the I/O iterator
2240	  (iov_iter). This test is executed only once during system boot (so
2241	  affects only boot time), or at module load time.
2242
2243	  If unsure, say N.
2244
2245config KPROBES_SANITY_TEST
2246	tristate "Kprobes sanity tests" if !KUNIT_ALL_TESTS
2247	depends on DEBUG_KERNEL
2248	depends on KPROBES
2249	depends on KUNIT
2250	select STACKTRACE if ARCH_CORRECT_STACKTRACE_ON_KRETPROBE
2251	default KUNIT_ALL_TESTS
2252	help
2253	  This option provides for testing basic kprobes functionality on
2254	  boot. Samples of kprobe and kretprobe are inserted and
2255	  verified for functionality.
2256
2257	  Say N if you are unsure.
2258
2259config FPROBE_SANITY_TEST
2260	bool "Self test for fprobe"
2261	depends on DEBUG_KERNEL
2262	depends on FPROBE
2263	depends on KUNIT=y
2264	help
2265	  This option will enable testing the fprobe when the system boot.
2266	  A series of tests are made to verify that the fprobe is functioning
2267	  properly.
2268
2269	  Say N if you are unsure.
2270
2271config BACKTRACE_SELF_TEST
2272	tristate "Self test for the backtrace code"
2273	depends on DEBUG_KERNEL
2274	help
2275	  This option provides a kernel module that can be used to test
2276	  the kernel stack backtrace code. This option is not useful
2277	  for distributions or general kernels, but only for kernel
2278	  developers working on architecture code.
2279
2280	  Note that if you want to also test saved backtraces, you will
2281	  have to enable STACKTRACE as well.
2282
2283	  Say N if you are unsure.
2284
2285config TEST_REF_TRACKER
2286	tristate "Self test for reference tracker"
2287	depends on DEBUG_KERNEL && STACKTRACE_SUPPORT
2288	select REF_TRACKER
2289	help
2290	  This option provides a kernel module performing tests
2291	  using reference tracker infrastructure.
2292
2293	  Say N if you are unsure.
2294
2295config RBTREE_TEST
2296	tristate "Red-Black tree test"
2297	depends on DEBUG_KERNEL
2298	help
2299	  A benchmark measuring the performance of the rbtree library.
2300	  Also includes rbtree invariant checks.
2301
2302config REED_SOLOMON_TEST
2303	tristate "Reed-Solomon library test"
2304	depends on DEBUG_KERNEL || m
2305	select REED_SOLOMON
2306	select REED_SOLOMON_ENC16
2307	select REED_SOLOMON_DEC16
2308	help
2309	  This option enables the self-test function of rslib at boot,
2310	  or at module load time.
2311
2312	  If unsure, say N.
2313
2314config INTERVAL_TREE_TEST
2315	tristate "Interval tree test"
2316	depends on DEBUG_KERNEL
2317	select INTERVAL_TREE
2318	help
2319	  A benchmark measuring the performance of the interval tree library
2320
2321config PERCPU_TEST
2322	tristate "Per cpu operations test"
2323	depends on m && DEBUG_KERNEL
2324	help
2325	  Enable this option to build test module which validates per-cpu
2326	  operations.
2327
2328	  If unsure, say N.
2329
2330config ATOMIC64_SELFTEST
2331	tristate "Perform an atomic64_t self-test"
2332	help
2333	  Enable this option to test the atomic64_t functions at boot or
2334	  at module load time.
2335
2336	  If unsure, say N.
2337
2338config ASYNC_RAID6_TEST
2339	tristate "Self test for hardware accelerated raid6 recovery"
2340	depends on ASYNC_RAID6_RECOV
2341	select ASYNC_MEMCPY
2342	help
2343	  This is a one-shot self test that permutes through the
2344	  recovery of all the possible two disk failure scenarios for a
2345	  N-disk array.  Recovery is performed with the asynchronous
2346	  raid6 recovery routines, and will optionally use an offload
2347	  engine if one is available.
2348
2349	  If unsure, say N.
2350
2351config TEST_HEXDUMP
2352	tristate "Test functions located in the hexdump module at runtime"
2353
2354config STRING_SELFTEST
2355	tristate "Test string functions at runtime"
2356
2357config TEST_STRING_HELPERS
2358	tristate "Test functions located in the string_helpers module at runtime"
2359
2360config TEST_KSTRTOX
2361	tristate "Test kstrto*() family of functions at runtime"
2362
2363config TEST_PRINTF
2364	tristate "Test printf() family of functions at runtime"
2365
2366config TEST_SCANF
2367	tristate "Test scanf() family of functions at runtime"
2368
2369config TEST_BITMAP
2370	tristate "Test bitmap_*() family of functions at runtime"
2371	help
2372	  Enable this option to test the bitmap functions at boot.
2373
2374	  If unsure, say N.
2375
2376config TEST_UUID
2377	tristate "Test functions located in the uuid module at runtime"
2378
2379config TEST_XARRAY
2380	tristate "Test the XArray code at runtime"
2381
2382config TEST_MAPLE_TREE
2383	tristate "Test the Maple Tree code at runtime or module load"
2384	help
2385	  Enable this option to test the maple tree code functions at boot, or
2386	  when the module is loaded. Enable "Debug Maple Trees" will enable
2387	  more verbose output on failures.
2388
2389	  If unsure, say N.
2390
2391config TEST_RHASHTABLE
2392	tristate "Perform selftest on resizable hash table"
2393	help
2394	  Enable this option to test the rhashtable functions at boot.
2395
2396	  If unsure, say N.
2397
2398config TEST_IDA
2399	tristate "Perform selftest on IDA functions"
2400
2401config TEST_PARMAN
2402	tristate "Perform selftest on priority array manager"
2403	depends on PARMAN
2404	help
2405	  Enable this option to test priority array manager on boot
2406	  (or module load).
2407
2408	  If unsure, say N.
2409
2410config TEST_IRQ_TIMINGS
2411	bool "IRQ timings selftest"
2412	depends on IRQ_TIMINGS
2413	help
2414	  Enable this option to test the irq timings code on boot.
2415
2416	  If unsure, say N.
2417
2418config TEST_LKM
2419	tristate "Test module loading with 'hello world' module"
2420	depends on m
2421	help
2422	  This builds the "test_module" module that emits "Hello, world"
2423	  on printk when loaded. It is designed to be used for basic
2424	  evaluation of the module loading subsystem (for example when
2425	  validating module verification). It lacks any extra dependencies,
2426	  and will not normally be loaded by the system unless explicitly
2427	  requested by name.
2428
2429	  If unsure, say N.
2430
2431config TEST_BITOPS
2432	tristate "Test module for compilation of bitops operations"
2433	depends on m
2434	help
2435	  This builds the "test_bitops" module that is much like the
2436	  TEST_LKM module except that it does a basic exercise of the
2437	  set/clear_bit macros and get_count_order/long to make sure there are
2438	  no compiler warnings from C=1 sparse checker or -Wextra
2439	  compilations. It has no dependencies and doesn't run or load unless
2440	  explicitly requested by name.  for example: modprobe test_bitops.
2441
2442	  If unsure, say N.
2443
2444config TEST_VMALLOC
2445	tristate "Test module for stress/performance analysis of vmalloc allocator"
2446	default n
2447       depends on MMU
2448	depends on m
2449	help
2450	  This builds the "test_vmalloc" module that should be used for
2451	  stress and performance analysis. So, any new change for vmalloc
2452	  subsystem can be evaluated from performance and stability point
2453	  of view.
2454
2455	  If unsure, say N.
2456
2457config TEST_USER_COPY
2458	tristate "Test user/kernel boundary protections"
2459	depends on m
2460	help
2461	  This builds the "test_user_copy" module that runs sanity checks
2462	  on the copy_to/from_user infrastructure, making sure basic
2463	  user/kernel boundary testing is working. If it fails to load,
2464	  a regression has been detected in the user/kernel memory boundary
2465	  protections.
2466
2467	  If unsure, say N.
2468
2469config TEST_BPF
2470	tristate "Test BPF filter functionality"
2471	depends on m && NET
2472	help
2473	  This builds the "test_bpf" module that runs various test vectors
2474	  against the BPF interpreter or BPF JIT compiler depending on the
2475	  current setting. This is in particular useful for BPF JIT compiler
2476	  development, but also to run regression tests against changes in
2477	  the interpreter code. It also enables test stubs for eBPF maps and
2478	  verifier used by user space verifier testsuite.
2479
2480	  If unsure, say N.
2481
2482config TEST_BLACKHOLE_DEV
2483	tristate "Test blackhole netdev functionality"
2484	depends on m && NET
2485	help
2486	  This builds the "test_blackhole_dev" module that validates the
2487	  data path through this blackhole netdev.
2488
2489	  If unsure, say N.
2490
2491config FIND_BIT_BENCHMARK
2492	tristate "Test find_bit functions"
2493	help
2494	  This builds the "test_find_bit" module that measure find_*_bit()
2495	  functions performance.
2496
2497	  If unsure, say N.
2498
2499config TEST_FIRMWARE
2500	tristate "Test firmware loading via userspace interface"
2501	depends on FW_LOADER
2502	help
2503	  This builds the "test_firmware" module that creates a userspace
2504	  interface for testing firmware loading. This can be used to
2505	  control the triggering of firmware loading without needing an
2506	  actual firmware-using device. The contents can be rechecked by
2507	  userspace.
2508
2509	  If unsure, say N.
2510
2511config TEST_SYSCTL
2512	tristate "sysctl test driver"
2513	depends on PROC_SYSCTL
2514	help
2515	  This builds the "test_sysctl" module. This driver enables to test the
2516	  proc sysctl interfaces available to drivers safely without affecting
2517	  production knobs which might alter system functionality.
2518
2519	  If unsure, say N.
2520
2521config BITFIELD_KUNIT
2522	tristate "KUnit test bitfield functions at runtime" if !KUNIT_ALL_TESTS
2523	depends on KUNIT
2524	default KUNIT_ALL_TESTS
2525	help
2526	  Enable this option to test the bitfield functions at boot.
2527
2528	  KUnit tests run during boot and output the results to the debug log
2529	  in TAP format (http://testanything.org/). Only useful for kernel devs
2530	  running the KUnit test harness, and not intended for inclusion into a
2531	  production build.
2532
2533	  For more information on KUnit and unit tests in general please refer
2534	  to the KUnit documentation in Documentation/dev-tools/kunit/.
2535
2536	  If unsure, say N.
2537
2538config CHECKSUM_KUNIT
2539	tristate "KUnit test checksum functions at runtime" if !KUNIT_ALL_TESTS
2540	depends on KUNIT
2541	default KUNIT_ALL_TESTS
2542	help
2543	  Enable this option to test the checksum functions at boot.
2544
2545	  KUnit tests run during boot and output the results to the debug log
2546	  in TAP format (http://testanything.org/). Only useful for kernel devs
2547	  running the KUnit test harness, and not intended for inclusion into a
2548	  production build.
2549
2550	  For more information on KUnit and unit tests in general please refer
2551	  to the KUnit documentation in Documentation/dev-tools/kunit/.
2552
2553	  If unsure, say N.
2554
2555config HASH_KUNIT_TEST
2556	tristate "KUnit Test for integer hash functions" if !KUNIT_ALL_TESTS
2557	depends on KUNIT
2558	default KUNIT_ALL_TESTS
2559	help
2560	  Enable this option to test the kernel's string (<linux/stringhash.h>), and
2561	  integer (<linux/hash.h>) hash functions on boot.
2562
2563	  KUnit tests run during boot and output the results to the debug log
2564	  in TAP format (https://testanything.org/). Only useful for kernel devs
2565	  running the KUnit test harness, and not intended for inclusion into a
2566	  production build.
2567
2568	  For more information on KUnit and unit tests in general please refer
2569	  to the KUnit documentation in Documentation/dev-tools/kunit/.
2570
2571	  This is intended to help people writing architecture-specific
2572	  optimized versions. If unsure, say N.
2573
2574config RESOURCE_KUNIT_TEST
2575	tristate "KUnit test for resource API" if !KUNIT_ALL_TESTS
2576	depends on KUNIT
2577	default KUNIT_ALL_TESTS
2578	help
2579	  This builds the resource API unit test.
2580	  Tests the logic of API provided by resource.c and ioport.h.
2581	  For more information on KUnit and unit tests in general please refer
2582	  to the KUnit documentation in Documentation/dev-tools/kunit/.
2583
2584	  If unsure, say N.
2585
2586config SYSCTL_KUNIT_TEST
2587	tristate "KUnit test for sysctl" if !KUNIT_ALL_TESTS
2588	depends on KUNIT
2589	default KUNIT_ALL_TESTS
2590	help
2591	  This builds the proc sysctl unit test, which runs on boot.
2592	  Tests the API contract and implementation correctness of sysctl.
2593	  For more information on KUnit and unit tests in general please refer
2594	  to the KUnit documentation in Documentation/dev-tools/kunit/.
2595
2596	  If unsure, say N.
2597
2598config LIST_KUNIT_TEST
2599	tristate "KUnit Test for Kernel Linked-list structures" if !KUNIT_ALL_TESTS
2600	depends on KUNIT
2601	default KUNIT_ALL_TESTS
2602	help
2603	  This builds the linked list KUnit test suite.
2604	  It tests that the API and basic functionality of the list_head type
2605	  and associated macros.
2606
2607	  KUnit tests run during boot and output the results to the debug log
2608	  in TAP format (https://testanything.org/). Only useful for kernel devs
2609	  running the KUnit test harness, and not intended for inclusion into a
2610	  production build.
2611
2612	  For more information on KUnit and unit tests in general please refer
2613	  to the KUnit documentation in Documentation/dev-tools/kunit/.
2614
2615	  If unsure, say N.
2616
2617config HASHTABLE_KUNIT_TEST
2618	tristate "KUnit Test for Kernel Hashtable structures" if !KUNIT_ALL_TESTS
2619	depends on KUNIT
2620	default KUNIT_ALL_TESTS
2621	help
2622	  This builds the hashtable KUnit test suite.
2623	  It tests the basic functionality of the API defined in
2624	  include/linux/hashtable.h. For more information on KUnit and
2625	  unit tests in general please refer to the KUnit documentation
2626	  in Documentation/dev-tools/kunit/.
2627
2628	  If unsure, say N.
2629
2630config LINEAR_RANGES_TEST
2631	tristate "KUnit test for linear_ranges"
2632	depends on KUNIT
2633	select LINEAR_RANGES
2634	help
2635	  This builds the linear_ranges unit test, which runs on boot.
2636	  Tests the linear_ranges logic correctness.
2637	  For more information on KUnit and unit tests in general please refer
2638	  to the KUnit documentation in Documentation/dev-tools/kunit/.
2639
2640	  If unsure, say N.
2641
2642config CMDLINE_KUNIT_TEST
2643	tristate "KUnit test for cmdline API" if !KUNIT_ALL_TESTS
2644	depends on KUNIT
2645	default KUNIT_ALL_TESTS
2646	help
2647	  This builds the cmdline API unit test.
2648	  Tests the logic of API provided by cmdline.c.
2649	  For more information on KUnit and unit tests in general please refer
2650	  to the KUnit documentation in Documentation/dev-tools/kunit/.
2651
2652	  If unsure, say N.
2653
2654config BITS_TEST
2655	tristate "KUnit test for bits.h" if !KUNIT_ALL_TESTS
2656	depends on KUNIT
2657	default KUNIT_ALL_TESTS
2658	help
2659	  This builds the bits unit test.
2660	  Tests the logic of macros defined in bits.h.
2661	  For more information on KUnit and unit tests in general please refer
2662	  to the KUnit documentation in Documentation/dev-tools/kunit/.
2663
2664	  If unsure, say N.
2665
2666config SLUB_KUNIT_TEST
2667	tristate "KUnit test for SLUB cache error detection" if !KUNIT_ALL_TESTS
2668	depends on SLUB_DEBUG && KUNIT
2669	default KUNIT_ALL_TESTS
2670	help
2671	  This builds SLUB allocator unit test.
2672	  Tests SLUB cache debugging functionality.
2673	  For more information on KUnit and unit tests in general please refer
2674	  to the KUnit documentation in Documentation/dev-tools/kunit/.
2675
2676	  If unsure, say N.
2677
2678config RATIONAL_KUNIT_TEST
2679	tristate "KUnit test for rational.c" if !KUNIT_ALL_TESTS
2680	depends on KUNIT && RATIONAL
2681	default KUNIT_ALL_TESTS
2682	help
2683	  This builds the rational math unit test.
2684	  For more information on KUnit and unit tests in general please refer
2685	  to the KUnit documentation in Documentation/dev-tools/kunit/.
2686
2687	  If unsure, say N.
2688
2689config MEMCPY_KUNIT_TEST
2690	tristate "Test memcpy(), memmove(), and memset() functions at runtime" if !KUNIT_ALL_TESTS
2691	depends on KUNIT
2692	default KUNIT_ALL_TESTS
2693	help
2694	  Builds unit tests for memcpy(), memmove(), and memset() functions.
2695	  For more information on KUnit and unit tests in general please refer
2696	  to the KUnit documentation in Documentation/dev-tools/kunit/.
2697
2698	  If unsure, say N.
2699
2700config MEMCPY_SLOW_KUNIT_TEST
2701	bool "Include exhaustive memcpy tests"
2702	depends on MEMCPY_KUNIT_TEST
2703	default y
2704	help
2705	  Some memcpy tests are quite exhaustive in checking for overlaps
2706	  and bit ranges. These can be very slow, so they are split out
2707	  as a separate config, in case they need to be disabled.
2708
2709	  Note this config option will be replaced by the use of KUnit test
2710	  attributes.
2711
2712config IS_SIGNED_TYPE_KUNIT_TEST
2713	tristate "Test is_signed_type() macro" if !KUNIT_ALL_TESTS
2714	depends on KUNIT
2715	default KUNIT_ALL_TESTS
2716	help
2717	  Builds unit tests for the is_signed_type() macro.
2718
2719	  For more information on KUnit and unit tests in general please refer
2720	  to the KUnit documentation in Documentation/dev-tools/kunit/.
2721
2722	  If unsure, say N.
2723
2724config OVERFLOW_KUNIT_TEST
2725	tristate "Test check_*_overflow() functions at runtime" if !KUNIT_ALL_TESTS
2726	depends on KUNIT
2727	default KUNIT_ALL_TESTS
2728	help
2729	  Builds unit tests for the check_*_overflow(), size_*(), allocation, and
2730	  related functions.
2731
2732	  For more information on KUnit and unit tests in general please refer
2733	  to the KUnit documentation in Documentation/dev-tools/kunit/.
2734
2735	  If unsure, say N.
2736
2737config STACKINIT_KUNIT_TEST
2738	tristate "Test level of stack variable initialization" if !KUNIT_ALL_TESTS
2739	depends on KUNIT
2740	default KUNIT_ALL_TESTS
2741	help
2742	  Test if the kernel is zero-initializing stack variables and
2743	  padding. Coverage is controlled by compiler flags,
2744	  CONFIG_INIT_STACK_ALL_PATTERN, CONFIG_INIT_STACK_ALL_ZERO,
2745	  CONFIG_GCC_PLUGIN_STRUCTLEAK, CONFIG_GCC_PLUGIN_STRUCTLEAK_BYREF,
2746	  or CONFIG_GCC_PLUGIN_STRUCTLEAK_BYREF_ALL.
2747
2748config FORTIFY_KUNIT_TEST
2749	tristate "Test fortified str*() and mem*() function internals at runtime" if !KUNIT_ALL_TESTS
2750	depends on KUNIT && FORTIFY_SOURCE
2751	default KUNIT_ALL_TESTS
2752	help
2753	  Builds unit tests for checking internals of FORTIFY_SOURCE as used
2754	  by the str*() and mem*() family of functions. For testing runtime
2755	  traps of FORTIFY_SOURCE, see LKDTM's "FORTIFY_*" tests.
2756
2757config HW_BREAKPOINT_KUNIT_TEST
2758	bool "Test hw_breakpoint constraints accounting" if !KUNIT_ALL_TESTS
2759	depends on HAVE_HW_BREAKPOINT
2760	depends on KUNIT=y
2761	default KUNIT_ALL_TESTS
2762	help
2763	  Tests for hw_breakpoint constraints accounting.
2764
2765	  If unsure, say N.
2766
2767config STRCAT_KUNIT_TEST
2768	tristate "Test strcat() family of functions at runtime" if !KUNIT_ALL_TESTS
2769	depends on KUNIT
2770	default KUNIT_ALL_TESTS
2771
2772config STRSCPY_KUNIT_TEST
2773	tristate "Test strscpy*() family of functions at runtime" if !KUNIT_ALL_TESTS
2774	depends on KUNIT
2775	default KUNIT_ALL_TESTS
2776
2777config SIPHASH_KUNIT_TEST
2778	tristate "Perform selftest on siphash functions" if !KUNIT_ALL_TESTS
2779	depends on KUNIT
2780	default KUNIT_ALL_TESTS
2781	help
2782	  Enable this option to test the kernel's siphash (<linux/siphash.h>) hash
2783	  functions on boot (or module load).
2784
2785	  This is intended to help people writing architecture-specific
2786	  optimized versions.  If unsure, say N.
2787
2788config TEST_UDELAY
2789	tristate "udelay test driver"
2790	help
2791	  This builds the "udelay_test" module that helps to make sure
2792	  that udelay() is working properly.
2793
2794	  If unsure, say N.
2795
2796config TEST_STATIC_KEYS
2797	tristate "Test static keys"
2798	depends on m
2799	help
2800	  Test the static key interfaces.
2801
2802	  If unsure, say N.
2803
2804config TEST_DYNAMIC_DEBUG
2805	tristate "Test DYNAMIC_DEBUG"
2806	depends on DYNAMIC_DEBUG
2807	help
2808	  This module registers a tracer callback to count enabled
2809	  pr_debugs in a 'do_debugging' function, then alters their
2810	  enablements, calls the function, and compares counts.
2811
2812	  If unsure, say N.
2813
2814config TEST_KMOD
2815	tristate "kmod stress tester"
2816	depends on m
2817	depends on NETDEVICES && NET_CORE && INET # for TUN
2818	depends on BLOCK
2819	depends on PAGE_SIZE_LESS_THAN_256KB # for BTRFS
2820	select TEST_LKM
2821	select XFS_FS
2822	select TUN
2823	select BTRFS_FS
2824	help
2825	  Test the kernel's module loading mechanism: kmod. kmod implements
2826	  support to load modules using the Linux kernel's usermode helper.
2827	  This test provides a series of tests against kmod.
2828
2829	  Although technically you can either build test_kmod as a module or
2830	  into the kernel we disallow building it into the kernel since
2831	  it stress tests request_module() and this will very likely cause
2832	  some issues by taking over precious threads available from other
2833	  module load requests, ultimately this could be fatal.
2834
2835	  To run tests run:
2836
2837	  tools/testing/selftests/kmod/kmod.sh --help
2838
2839	  If unsure, say N.
2840
2841config TEST_DEBUG_VIRTUAL
2842	tristate "Test CONFIG_DEBUG_VIRTUAL feature"
2843	depends on DEBUG_VIRTUAL
2844	help
2845	  Test the kernel's ability to detect incorrect calls to
2846	  virt_to_phys() done against the non-linear part of the
2847	  kernel's virtual address map.
2848
2849	  If unsure, say N.
2850
2851config TEST_MEMCAT_P
2852	tristate "Test memcat_p() helper function"
2853	help
2854	  Test the memcat_p() helper for correctly merging two
2855	  pointer arrays together.
2856
2857	  If unsure, say N.
2858
2859config TEST_LIVEPATCH
2860	tristate "Test livepatching"
2861	default n
2862	depends on DYNAMIC_DEBUG
2863	depends on LIVEPATCH
2864	depends on m
2865	help
2866	  Test kernel livepatching features for correctness.  The tests will
2867	  load test modules that will be livepatched in various scenarios.
2868
2869	  To run all the livepatching tests:
2870
2871	  make -C tools/testing/selftests TARGETS=livepatch run_tests
2872
2873	  Alternatively, individual tests may be invoked:
2874
2875	  tools/testing/selftests/livepatch/test-callbacks.sh
2876	  tools/testing/selftests/livepatch/test-livepatch.sh
2877	  tools/testing/selftests/livepatch/test-shadow-vars.sh
2878
2879	  If unsure, say N.
2880
2881config TEST_OBJAGG
2882	tristate "Perform selftest on object aggreration manager"
2883	default n
2884	depends on OBJAGG
2885	help
2886	  Enable this option to test object aggregation manager on boot
2887	  (or module load).
2888
2889config TEST_MEMINIT
2890	tristate "Test heap/page initialization"
2891	help
2892	  Test if the kernel is zero-initializing heap and page allocations.
2893	  This can be useful to test init_on_alloc and init_on_free features.
2894
2895	  If unsure, say N.
2896
2897config TEST_HMM
2898	tristate "Test HMM (Heterogeneous Memory Management)"
2899	depends on TRANSPARENT_HUGEPAGE
2900	depends on DEVICE_PRIVATE
2901	select HMM_MIRROR
2902	select MMU_NOTIFIER
2903	help
2904	  This is a pseudo device driver solely for testing HMM.
2905	  Say M here if you want to build the HMM test module.
2906	  Doing so will allow you to run tools/testing/selftest/vm/hmm-tests.
2907
2908	  If unsure, say N.
2909
2910config TEST_FREE_PAGES
2911	tristate "Test freeing pages"
2912	help
2913	  Test that a memory leak does not occur due to a race between
2914	  freeing a block of pages and a speculative page reference.
2915	  Loading this module is safe if your kernel has the bug fixed.
2916	  If the bug is not fixed, it will leak gigabytes of memory and
2917	  probably OOM your system.
2918
2919config TEST_FPU
2920	tristate "Test floating point operations in kernel space"
2921	depends on X86 && !KCOV_INSTRUMENT_ALL
2922	help
2923	  Enable this option to add /sys/kernel/debug/selftest_helpers/test_fpu
2924	  which will trigger a sequence of floating point operations. This is used
2925	  for self-testing floating point control register setting in
2926	  kernel_fpu_begin().
2927
2928	  If unsure, say N.
2929
2930config TEST_CLOCKSOURCE_WATCHDOG
2931	tristate "Test clocksource watchdog in kernel space"
2932	depends on CLOCKSOURCE_WATCHDOG
2933	help
2934	  Enable this option to create a kernel module that will trigger
2935	  a test of the clocksource watchdog.  This module may be loaded
2936	  via modprobe or insmod in which case it will run upon being
2937	  loaded, or it may be built in, in which case it will run
2938	  shortly after boot.
2939
2940	  If unsure, say N.
2941
2942endif # RUNTIME_TESTING_MENU
2943
2944config ARCH_USE_MEMTEST
2945	bool
2946	help
2947	  An architecture should select this when it uses early_memtest()
2948	  during boot process.
2949
2950config MEMTEST
2951	bool "Memtest"
2952	depends on ARCH_USE_MEMTEST
2953	help
2954	  This option adds a kernel parameter 'memtest', which allows memtest
2955	  to be set and executed.
2956	        memtest=0, mean disabled; -- default
2957	        memtest=1, mean do 1 test pattern;
2958	        ...
2959	        memtest=17, mean do 17 test patterns.
2960	  If you are unsure how to answer this question, answer N.
2961
2962
2963
2964config HYPERV_TESTING
2965	bool "Microsoft Hyper-V driver testing"
2966	default n
2967	depends on HYPERV && DEBUG_FS
2968	help
2969	  Select this option to enable Hyper-V vmbus testing.
2970
2971endmenu # "Kernel Testing and Coverage"
2972
2973menu "Rust hacking"
2974
2975config RUST_DEBUG_ASSERTIONS
2976	bool "Debug assertions"
2977	depends on RUST
2978	help
2979	  Enables rustc's `-Cdebug-assertions` codegen option.
2980
2981	  This flag lets you turn `cfg(debug_assertions)` conditional
2982	  compilation on or off. This can be used to enable extra debugging
2983	  code in development but not in production. For example, it controls
2984	  the behavior of the standard library's `debug_assert!` macro.
2985
2986	  Note that this will apply to all Rust code, including `core`.
2987
2988	  If unsure, say N.
2989
2990config RUST_OVERFLOW_CHECKS
2991	bool "Overflow checks"
2992	default y
2993	depends on RUST
2994	help
2995	  Enables rustc's `-Coverflow-checks` codegen option.
2996
2997	  This flag allows you to control the behavior of runtime integer
2998	  overflow. When overflow-checks are enabled, a Rust panic will occur
2999	  on overflow.
3000
3001	  Note that this will apply to all Rust code, including `core`.
3002
3003	  If unsure, say Y.
3004
3005config RUST_BUILD_ASSERT_ALLOW
3006	bool "Allow unoptimized build-time assertions"
3007	depends on RUST
3008	help
3009	  Controls how `build_error!` and `build_assert!` are handled during the build.
3010
3011	  If calls to them exist in the binary, it may indicate a violated invariant
3012	  or that the optimizer failed to verify the invariant during compilation.
3013
3014	  This should not happen, thus by default the build is aborted. However,
3015	  as an escape hatch, you can choose Y here to ignore them during build
3016	  and let the check be carried at runtime (with `panic!` being called if
3017	  the check fails).
3018
3019	  If unsure, say N.
3020
3021config RUST_KERNEL_DOCTESTS
3022	bool "Doctests for the `kernel` crate" if !KUNIT_ALL_TESTS
3023	depends on RUST && KUNIT=y
3024	default KUNIT_ALL_TESTS
3025	help
3026	  This builds the documentation tests of the `kernel` crate
3027	  as KUnit tests.
3028
3029	  For more information on KUnit and unit tests in general,
3030	  please refer to the KUnit documentation in Documentation/dev-tools/kunit/.
3031
3032	  If unsure, say N.
3033
3034endmenu # "Rust"
3035
3036endmenu # Kernel hacking
3037