xref: /openbmc/linux/arch/Kconfig (revision 0cf51bfe)
1# SPDX-License-Identifier: GPL-2.0
2#
3# General architecture dependent options
4#
5
6#
7# Note: arch/$(SRCARCH)/Kconfig needs to be included first so that it can
8# override the default values in this file.
9#
10source "arch/$(SRCARCH)/Kconfig"
11
12menu "General architecture-dependent options"
13
14config CRASH_CORE
15	bool
16
17config KEXEC_CORE
18	select CRASH_CORE
19	bool
20
21config KEXEC_ELF
22	bool
23
24config HAVE_IMA_KEXEC
25	bool
26
27config ARCH_HAS_SUBPAGE_FAULTS
28	bool
29	help
30	  Select if the architecture can check permissions at sub-page
31	  granularity (e.g. arm64 MTE). The probe_user_*() functions
32	  must be implemented.
33
34config HOTPLUG_SMT
35	bool
36
37config GENERIC_ENTRY
38       bool
39
40config KPROBES
41	bool "Kprobes"
42	depends on MODULES
43	depends on HAVE_KPROBES
44	select KALLSYMS
45	select TASKS_RCU if PREEMPTION
46	help
47	  Kprobes allows you to trap at almost any kernel address and
48	  execute a callback function.  register_kprobe() establishes
49	  a probepoint and specifies the callback.  Kprobes is useful
50	  for kernel debugging, non-intrusive instrumentation and testing.
51	  If in doubt, say "N".
52
53config JUMP_LABEL
54	bool "Optimize very unlikely/likely branches"
55	depends on HAVE_ARCH_JUMP_LABEL
56	depends on CC_HAS_ASM_GOTO
57	select OBJTOOL if HAVE_JUMP_LABEL_HACK
58	help
59	 This option enables a transparent branch optimization that
60	 makes certain almost-always-true or almost-always-false branch
61	 conditions even cheaper to execute within the kernel.
62
63	 Certain performance-sensitive kernel code, such as trace points,
64	 scheduler functionality, networking code and KVM have such
65	 branches and include support for this optimization technique.
66
67	 If it is detected that the compiler has support for "asm goto",
68	 the kernel will compile such branches with just a nop
69	 instruction. When the condition flag is toggled to true, the
70	 nop will be converted to a jump instruction to execute the
71	 conditional block of instructions.
72
73	 This technique lowers overhead and stress on the branch prediction
74	 of the processor and generally makes the kernel faster. The update
75	 of the condition is slower, but those are always very rare.
76
77	 ( On 32-bit x86, the necessary options added to the compiler
78	   flags may increase the size of the kernel slightly. )
79
80config STATIC_KEYS_SELFTEST
81	bool "Static key selftest"
82	depends on JUMP_LABEL
83	help
84	  Boot time self-test of the branch patching code.
85
86config STATIC_CALL_SELFTEST
87	bool "Static call selftest"
88	depends on HAVE_STATIC_CALL
89	help
90	  Boot time self-test of the call patching code.
91
92config OPTPROBES
93	def_bool y
94	depends on KPROBES && HAVE_OPTPROBES
95	select TASKS_RCU if PREEMPTION
96
97config KPROBES_ON_FTRACE
98	def_bool y
99	depends on KPROBES && HAVE_KPROBES_ON_FTRACE
100	depends on DYNAMIC_FTRACE_WITH_REGS
101	help
102	 If function tracer is enabled and the arch supports full
103	 passing of pt_regs to function tracing, then kprobes can
104	 optimize on top of function tracing.
105
106config UPROBES
107	def_bool n
108	depends on ARCH_SUPPORTS_UPROBES
109	help
110	  Uprobes is the user-space counterpart to kprobes: they
111	  enable instrumentation applications (such as 'perf probe')
112	  to establish unintrusive probes in user-space binaries and
113	  libraries, by executing handler functions when the probes
114	  are hit by user-space applications.
115
116	  ( These probes come in the form of single-byte breakpoints,
117	    managed by the kernel and kept transparent to the probed
118	    application. )
119
120config HAVE_64BIT_ALIGNED_ACCESS
121	def_bool 64BIT && !HAVE_EFFICIENT_UNALIGNED_ACCESS
122	help
123	  Some architectures require 64 bit accesses to be 64 bit
124	  aligned, which also requires structs containing 64 bit values
125	  to be 64 bit aligned too. This includes some 32 bit
126	  architectures which can do 64 bit accesses, as well as 64 bit
127	  architectures without unaligned access.
128
129	  This symbol should be selected by an architecture if 64 bit
130	  accesses are required to be 64 bit aligned in this way even
131	  though it is not a 64 bit architecture.
132
133	  See Documentation/core-api/unaligned-memory-access.rst for
134	  more information on the topic of unaligned memory accesses.
135
136config HAVE_EFFICIENT_UNALIGNED_ACCESS
137	bool
138	help
139	  Some architectures are unable to perform unaligned accesses
140	  without the use of get_unaligned/put_unaligned. Others are
141	  unable to perform such accesses efficiently (e.g. trap on
142	  unaligned access and require fixing it up in the exception
143	  handler.)
144
145	  This symbol should be selected by an architecture if it can
146	  perform unaligned accesses efficiently to allow different
147	  code paths to be selected for these cases. Some network
148	  drivers, for example, could opt to not fix up alignment
149	  problems with received packets if doing so would not help
150	  much.
151
152	  See Documentation/core-api/unaligned-memory-access.rst for more
153	  information on the topic of unaligned memory accesses.
154
155config ARCH_USE_BUILTIN_BSWAP
156	bool
157	help
158	 Modern versions of GCC (since 4.4) have builtin functions
159	 for handling byte-swapping. Using these, instead of the old
160	 inline assembler that the architecture code provides in the
161	 __arch_bswapXX() macros, allows the compiler to see what's
162	 happening and offers more opportunity for optimisation. In
163	 particular, the compiler will be able to combine the byteswap
164	 with a nearby load or store and use load-and-swap or
165	 store-and-swap instructions if the architecture has them. It
166	 should almost *never* result in code which is worse than the
167	 hand-coded assembler in <asm/swab.h>.  But just in case it
168	 does, the use of the builtins is optional.
169
170	 Any architecture with load-and-swap or store-and-swap
171	 instructions should set this. And it shouldn't hurt to set it
172	 on architectures that don't have such instructions.
173
174config KRETPROBES
175	def_bool y
176	depends on KPROBES && (HAVE_KRETPROBES || HAVE_RETHOOK)
177
178config KRETPROBE_ON_RETHOOK
179	def_bool y
180	depends on HAVE_RETHOOK
181	depends on KRETPROBES
182	select RETHOOK
183
184config USER_RETURN_NOTIFIER
185	bool
186	depends on HAVE_USER_RETURN_NOTIFIER
187	help
188	  Provide a kernel-internal notification when a cpu is about to
189	  switch to user mode.
190
191config HAVE_IOREMAP_PROT
192	bool
193
194config HAVE_KPROBES
195	bool
196
197config HAVE_KRETPROBES
198	bool
199
200config HAVE_OPTPROBES
201	bool
202
203config HAVE_KPROBES_ON_FTRACE
204	bool
205
206config ARCH_CORRECT_STACKTRACE_ON_KRETPROBE
207	bool
208	help
209	  Since kretprobes modifies return address on the stack, the
210	  stacktrace may see the kretprobe trampoline address instead
211	  of correct one. If the architecture stacktrace code and
212	  unwinder can adjust such entries, select this configuration.
213
214config HAVE_FUNCTION_ERROR_INJECTION
215	bool
216
217config HAVE_NMI
218	bool
219
220config HAVE_FUNCTION_DESCRIPTORS
221	bool
222
223config TRACE_IRQFLAGS_SUPPORT
224	bool
225
226#
227# An arch should select this if it provides all these things:
228#
229#	task_pt_regs()		in asm/processor.h or asm/ptrace.h
230#	arch_has_single_step()	if there is hardware single-step support
231#	arch_has_block_step()	if there is hardware block-step support
232#	asm/syscall.h		supplying asm-generic/syscall.h interface
233#	linux/regset.h		user_regset interfaces
234#	CORE_DUMP_USE_REGSET	#define'd in linux/elf.h
235#	TIF_SYSCALL_TRACE	calls ptrace_report_syscall_{entry,exit}
236#	TIF_NOTIFY_RESUME	calls resume_user_mode_work()
237#
238config HAVE_ARCH_TRACEHOOK
239	bool
240
241config HAVE_DMA_CONTIGUOUS
242	bool
243
244config GENERIC_SMP_IDLE_THREAD
245	bool
246
247config GENERIC_IDLE_POLL_SETUP
248	bool
249
250config ARCH_HAS_FORTIFY_SOURCE
251	bool
252	help
253	  An architecture should select this when it can successfully
254	  build and run with CONFIG_FORTIFY_SOURCE.
255
256#
257# Select if the arch provides a historic keepinit alias for the retain_initrd
258# command line option
259#
260config ARCH_HAS_KEEPINITRD
261	bool
262
263# Select if arch has all set_memory_ro/rw/x/nx() functions in asm/cacheflush.h
264config ARCH_HAS_SET_MEMORY
265	bool
266
267# Select if arch has all set_direct_map_invalid/default() functions
268config ARCH_HAS_SET_DIRECT_MAP
269	bool
270
271#
272# Select if the architecture provides the arch_dma_set_uncached symbol to
273# either provide an uncached segment alias for a DMA allocation, or
274# to remap the page tables in place.
275#
276config ARCH_HAS_DMA_SET_UNCACHED
277	bool
278
279#
280# Select if the architectures provides the arch_dma_clear_uncached symbol
281# to undo an in-place page table remap for uncached access.
282#
283config ARCH_HAS_DMA_CLEAR_UNCACHED
284	bool
285
286# Select if arch init_task must go in the __init_task_data section
287config ARCH_TASK_STRUCT_ON_STACK
288	bool
289
290# Select if arch has its private alloc_task_struct() function
291config ARCH_TASK_STRUCT_ALLOCATOR
292	bool
293
294config HAVE_ARCH_THREAD_STRUCT_WHITELIST
295	bool
296	depends on !ARCH_TASK_STRUCT_ALLOCATOR
297	help
298	  An architecture should select this to provide hardened usercopy
299	  knowledge about what region of the thread_struct should be
300	  whitelisted for copying to userspace. Normally this is only the
301	  FPU registers. Specifically, arch_thread_struct_whitelist()
302	  should be implemented. Without this, the entire thread_struct
303	  field in task_struct will be left whitelisted.
304
305# Select if arch has its private alloc_thread_stack() function
306config ARCH_THREAD_STACK_ALLOCATOR
307	bool
308
309# Select if arch wants to size task_struct dynamically via arch_task_struct_size:
310config ARCH_WANTS_DYNAMIC_TASK_STRUCT
311	bool
312
313config ARCH_WANTS_NO_INSTR
314	bool
315	help
316	  An architecture should select this if the noinstr macro is being used on
317	  functions to denote that the toolchain should avoid instrumenting such
318	  functions and is required for correctness.
319
320config ARCH_32BIT_OFF_T
321	bool
322	depends on !64BIT
323	help
324	  All new 32-bit architectures should have 64-bit off_t type on
325	  userspace side which corresponds to the loff_t kernel type. This
326	  is the requirement for modern ABIs. Some existing architectures
327	  still support 32-bit off_t. This option is enabled for all such
328	  architectures explicitly.
329
330# Selected by 64 bit architectures which have a 32 bit f_tinode in struct ustat
331config ARCH_32BIT_USTAT_F_TINODE
332	bool
333
334config HAVE_ASM_MODVERSIONS
335	bool
336	help
337	  This symbol should be selected by an architecture if it provides
338	  <asm/asm-prototypes.h> to support the module versioning for symbols
339	  exported from assembly code.
340
341config HAVE_REGS_AND_STACK_ACCESS_API
342	bool
343	help
344	  This symbol should be selected by an architecture if it supports
345	  the API needed to access registers and stack entries from pt_regs,
346	  declared in asm/ptrace.h
347	  For example the kprobes-based event tracer needs this API.
348
349config HAVE_RSEQ
350	bool
351	depends on HAVE_REGS_AND_STACK_ACCESS_API
352	help
353	  This symbol should be selected by an architecture if it
354	  supports an implementation of restartable sequences.
355
356config HAVE_FUNCTION_ARG_ACCESS_API
357	bool
358	help
359	  This symbol should be selected by an architecture if it supports
360	  the API needed to access function arguments from pt_regs,
361	  declared in asm/ptrace.h
362
363config HAVE_HW_BREAKPOINT
364	bool
365	depends on PERF_EVENTS
366
367config HAVE_MIXED_BREAKPOINTS_REGS
368	bool
369	depends on HAVE_HW_BREAKPOINT
370	help
371	  Depending on the arch implementation of hardware breakpoints,
372	  some of them have separate registers for data and instruction
373	  breakpoints addresses, others have mixed registers to store
374	  them but define the access type in a control register.
375	  Select this option if your arch implements breakpoints under the
376	  latter fashion.
377
378config HAVE_USER_RETURN_NOTIFIER
379	bool
380
381config HAVE_PERF_EVENTS_NMI
382	bool
383	help
384	  System hardware can generate an NMI using the perf event
385	  subsystem.  Also has support for calculating CPU cycle events
386	  to determine how many clock cycles in a given period.
387
388config HAVE_HARDLOCKUP_DETECTOR_PERF
389	bool
390	depends on HAVE_PERF_EVENTS_NMI
391	help
392	  The arch chooses to use the generic perf-NMI-based hardlockup
393	  detector. Must define HAVE_PERF_EVENTS_NMI.
394
395config HAVE_NMI_WATCHDOG
396	depends on HAVE_NMI
397	bool
398	help
399	  The arch provides a low level NMI watchdog. It provides
400	  asm/nmi.h, and defines its own arch_touch_nmi_watchdog().
401
402config HAVE_HARDLOCKUP_DETECTOR_ARCH
403	bool
404	select HAVE_NMI_WATCHDOG
405	help
406	  The arch chooses to provide its own hardlockup detector, which is
407	  a superset of the HAVE_NMI_WATCHDOG. It also conforms to config
408	  interfaces and parameters provided by hardlockup detector subsystem.
409
410config HAVE_PERF_REGS
411	bool
412	help
413	  Support selective register dumps for perf events. This includes
414	  bit-mapping of each registers and a unique architecture id.
415
416config HAVE_PERF_USER_STACK_DUMP
417	bool
418	help
419	  Support user stack dumps for perf event samples. This needs
420	  access to the user stack pointer which is not unified across
421	  architectures.
422
423config HAVE_ARCH_JUMP_LABEL
424	bool
425
426config HAVE_ARCH_JUMP_LABEL_RELATIVE
427	bool
428
429config MMU_GATHER_TABLE_FREE
430	bool
431
432config MMU_GATHER_RCU_TABLE_FREE
433	bool
434	select MMU_GATHER_TABLE_FREE
435
436config MMU_GATHER_PAGE_SIZE
437	bool
438
439config MMU_GATHER_NO_RANGE
440	bool
441
442config MMU_GATHER_NO_GATHER
443	bool
444	depends on MMU_GATHER_TABLE_FREE
445
446config ARCH_WANT_IRQS_OFF_ACTIVATE_MM
447	bool
448	help
449	  Temporary select until all architectures can be converted to have
450	  irqs disabled over activate_mm. Architectures that do IPI based TLB
451	  shootdowns should enable this.
452
453config ARCH_HAVE_NMI_SAFE_CMPXCHG
454	bool
455
456config HAVE_ALIGNED_STRUCT_PAGE
457	bool
458	help
459	  This makes sure that struct pages are double word aligned and that
460	  e.g. the SLUB allocator can perform double word atomic operations
461	  on a struct page for better performance. However selecting this
462	  might increase the size of a struct page by a word.
463
464config HAVE_CMPXCHG_LOCAL
465	bool
466
467config HAVE_CMPXCHG_DOUBLE
468	bool
469
470config ARCH_WEAK_RELEASE_ACQUIRE
471	bool
472
473config ARCH_WANT_IPC_PARSE_VERSION
474	bool
475
476config ARCH_WANT_COMPAT_IPC_PARSE_VERSION
477	bool
478
479config ARCH_WANT_OLD_COMPAT_IPC
480	select ARCH_WANT_COMPAT_IPC_PARSE_VERSION
481	bool
482
483config HAVE_ARCH_SECCOMP
484	bool
485	help
486	  An arch should select this symbol to support seccomp mode 1 (the fixed
487	  syscall policy), and must provide an overrides for __NR_seccomp_sigreturn,
488	  and compat syscalls if the asm-generic/seccomp.h defaults need adjustment:
489	  - __NR_seccomp_read_32
490	  - __NR_seccomp_write_32
491	  - __NR_seccomp_exit_32
492	  - __NR_seccomp_sigreturn_32
493
494config HAVE_ARCH_SECCOMP_FILTER
495	bool
496	select HAVE_ARCH_SECCOMP
497	help
498	  An arch should select this symbol if it provides all of these things:
499	  - all the requirements for HAVE_ARCH_SECCOMP
500	  - syscall_get_arch()
501	  - syscall_get_arguments()
502	  - syscall_rollback()
503	  - syscall_set_return_value()
504	  - SIGSYS siginfo_t support
505	  - secure_computing is called from a ptrace_event()-safe context
506	  - secure_computing return value is checked and a return value of -1
507	    results in the system call being skipped immediately.
508	  - seccomp syscall wired up
509	  - if !HAVE_SPARSE_SYSCALL_NR, have SECCOMP_ARCH_NATIVE,
510	    SECCOMP_ARCH_NATIVE_NR, SECCOMP_ARCH_NATIVE_NAME defined. If
511	    COMPAT is supported, have the SECCOMP_ARCH_COMPAT* defines too.
512
513config SECCOMP
514	prompt "Enable seccomp to safely execute untrusted bytecode"
515	def_bool y
516	depends on HAVE_ARCH_SECCOMP
517	help
518	  This kernel feature is useful for number crunching applications
519	  that may need to handle untrusted bytecode during their
520	  execution. By using pipes or other transports made available
521	  to the process as file descriptors supporting the read/write
522	  syscalls, it's possible to isolate those applications in their
523	  own address space using seccomp. Once seccomp is enabled via
524	  prctl(PR_SET_SECCOMP) or the seccomp() syscall, it cannot be
525	  disabled and the task is only allowed to execute a few safe
526	  syscalls defined by each seccomp mode.
527
528	  If unsure, say Y.
529
530config SECCOMP_FILTER
531	def_bool y
532	depends on HAVE_ARCH_SECCOMP_FILTER && SECCOMP && NET
533	help
534	  Enable tasks to build secure computing environments defined
535	  in terms of Berkeley Packet Filter programs which implement
536	  task-defined system call filtering polices.
537
538	  See Documentation/userspace-api/seccomp_filter.rst for details.
539
540config SECCOMP_CACHE_DEBUG
541	bool "Show seccomp filter cache status in /proc/pid/seccomp_cache"
542	depends on SECCOMP_FILTER && !HAVE_SPARSE_SYSCALL_NR
543	depends on PROC_FS
544	help
545	  This enables the /proc/pid/seccomp_cache interface to monitor
546	  seccomp cache data. The file format is subject to change. Reading
547	  the file requires CAP_SYS_ADMIN.
548
549	  This option is for debugging only. Enabling presents the risk that
550	  an adversary may be able to infer the seccomp filter logic.
551
552	  If unsure, say N.
553
554config HAVE_ARCH_STACKLEAK
555	bool
556	help
557	  An architecture should select this if it has the code which
558	  fills the used part of the kernel stack with the STACKLEAK_POISON
559	  value before returning from system calls.
560
561config HAVE_STACKPROTECTOR
562	bool
563	help
564	  An arch should select this symbol if:
565	  - it has implemented a stack canary (e.g. __stack_chk_guard)
566
567config STACKPROTECTOR
568	bool "Stack Protector buffer overflow detection"
569	depends on HAVE_STACKPROTECTOR
570	depends on $(cc-option,-fstack-protector)
571	default y
572	help
573	  This option turns on the "stack-protector" GCC feature. This
574	  feature puts, at the beginning of functions, a canary value on
575	  the stack just before the return address, and validates
576	  the value just before actually returning.  Stack based buffer
577	  overflows (that need to overwrite this return address) now also
578	  overwrite the canary, which gets detected and the attack is then
579	  neutralized via a kernel panic.
580
581	  Functions will have the stack-protector canary logic added if they
582	  have an 8-byte or larger character array on the stack.
583
584	  This feature requires gcc version 4.2 or above, or a distribution
585	  gcc with the feature backported ("-fstack-protector").
586
587	  On an x86 "defconfig" build, this feature adds canary checks to
588	  about 3% of all kernel functions, which increases kernel code size
589	  by about 0.3%.
590
591config STACKPROTECTOR_STRONG
592	bool "Strong Stack Protector"
593	depends on STACKPROTECTOR
594	depends on $(cc-option,-fstack-protector-strong)
595	default y
596	help
597	  Functions will have the stack-protector canary logic added in any
598	  of the following conditions:
599
600	  - local variable's address used as part of the right hand side of an
601	    assignment or function argument
602	  - local variable is an array (or union containing an array),
603	    regardless of array type or length
604	  - uses register local variables
605
606	  This feature requires gcc version 4.9 or above, or a distribution
607	  gcc with the feature backported ("-fstack-protector-strong").
608
609	  On an x86 "defconfig" build, this feature adds canary checks to
610	  about 20% of all kernel functions, which increases the kernel code
611	  size by about 2%.
612
613config ARCH_SUPPORTS_SHADOW_CALL_STACK
614	bool
615	help
616	  An architecture should select this if it supports the compiler's
617	  Shadow Call Stack and implements runtime support for shadow stack
618	  switching.
619
620config SHADOW_CALL_STACK
621	bool "Shadow Call Stack"
622	depends on ARCH_SUPPORTS_SHADOW_CALL_STACK
623	depends on DYNAMIC_FTRACE_WITH_REGS || !FUNCTION_GRAPH_TRACER
624	help
625	  This option enables the compiler's Shadow Call Stack, which
626	  uses a shadow stack to protect function return addresses from
627	  being overwritten by an attacker. More information can be found
628	  in the compiler's documentation:
629
630	  - Clang: https://clang.llvm.org/docs/ShadowCallStack.html
631	  - GCC: https://gcc.gnu.org/onlinedocs/gcc/Instrumentation-Options.html#Instrumentation-Options
632
633	  Note that security guarantees in the kernel differ from the
634	  ones documented for user space. The kernel must store addresses
635	  of shadow stacks in memory, which means an attacker capable of
636	  reading and writing arbitrary memory may be able to locate them
637	  and hijack control flow by modifying the stacks.
638
639config LTO
640	bool
641	help
642	  Selected if the kernel will be built using the compiler's LTO feature.
643
644config LTO_CLANG
645	bool
646	select LTO
647	help
648	  Selected if the kernel will be built using Clang's LTO feature.
649
650config ARCH_SUPPORTS_LTO_CLANG
651	bool
652	help
653	  An architecture should select this option if it supports:
654	  - compiling with Clang,
655	  - compiling inline assembly with Clang's integrated assembler,
656	  - and linking with LLD.
657
658config ARCH_SUPPORTS_LTO_CLANG_THIN
659	bool
660	help
661	  An architecture should select this option if it can support Clang's
662	  ThinLTO mode.
663
664config HAS_LTO_CLANG
665	def_bool y
666	depends on CC_IS_CLANG && LD_IS_LLD && AS_IS_LLVM
667	depends on $(success,$(NM) --help | head -n 1 | grep -qi llvm)
668	depends on $(success,$(AR) --help | head -n 1 | grep -qi llvm)
669	depends on ARCH_SUPPORTS_LTO_CLANG
670	depends on !FTRACE_MCOUNT_USE_RECORDMCOUNT
671	depends on !KASAN || KASAN_HW_TAGS
672	depends on !GCOV_KERNEL
673	help
674	  The compiler and Kconfig options support building with Clang's
675	  LTO.
676
677choice
678	prompt "Link Time Optimization (LTO)"
679	default LTO_NONE
680	help
681	  This option enables Link Time Optimization (LTO), which allows the
682	  compiler to optimize binaries globally.
683
684	  If unsure, select LTO_NONE. Note that LTO is very resource-intensive
685	  so it's disabled by default.
686
687config LTO_NONE
688	bool "None"
689	help
690	  Build the kernel normally, without Link Time Optimization (LTO).
691
692config LTO_CLANG_FULL
693	bool "Clang Full LTO (EXPERIMENTAL)"
694	depends on HAS_LTO_CLANG
695	depends on !COMPILE_TEST
696	select LTO_CLANG
697	help
698          This option enables Clang's full Link Time Optimization (LTO), which
699          allows the compiler to optimize the kernel globally. If you enable
700          this option, the compiler generates LLVM bitcode instead of ELF
701          object files, and the actual compilation from bitcode happens at
702          the LTO link step, which may take several minutes depending on the
703          kernel configuration. More information can be found from LLVM's
704          documentation:
705
706	    https://llvm.org/docs/LinkTimeOptimization.html
707
708	  During link time, this option can use a large amount of RAM, and
709	  may take much longer than the ThinLTO option.
710
711config LTO_CLANG_THIN
712	bool "Clang ThinLTO (EXPERIMENTAL)"
713	depends on HAS_LTO_CLANG && ARCH_SUPPORTS_LTO_CLANG_THIN
714	select LTO_CLANG
715	help
716	  This option enables Clang's ThinLTO, which allows for parallel
717	  optimization and faster incremental compiles compared to the
718	  CONFIG_LTO_CLANG_FULL option. More information can be found
719	  from Clang's documentation:
720
721	    https://clang.llvm.org/docs/ThinLTO.html
722
723	  If unsure, say Y.
724endchoice
725
726config ARCH_SUPPORTS_CFI_CLANG
727	bool
728	help
729	  An architecture should select this option if it can support Clang's
730	  Control-Flow Integrity (CFI) checking.
731
732config CFI_CLANG
733	bool "Use Clang's Control Flow Integrity (CFI)"
734	depends on LTO_CLANG && ARCH_SUPPORTS_CFI_CLANG
735	depends on CLANG_VERSION >= 140000
736	select KALLSYMS
737	help
738	  This option enables Clang’s forward-edge Control Flow Integrity
739	  (CFI) checking, where the compiler injects a runtime check to each
740	  indirect function call to ensure the target is a valid function with
741	  the correct static type. This restricts possible call targets and
742	  makes it more difficult for an attacker to exploit bugs that allow
743	  the modification of stored function pointers. More information can be
744	  found from Clang's documentation:
745
746	    https://clang.llvm.org/docs/ControlFlowIntegrity.html
747
748config CFI_CLANG_SHADOW
749	bool "Use CFI shadow to speed up cross-module checks"
750	default y
751	depends on CFI_CLANG && MODULES
752	help
753	  If you select this option, the kernel builds a fast look-up table of
754	  CFI check functions in loaded modules to reduce performance overhead.
755
756	  If unsure, say Y.
757
758config CFI_PERMISSIVE
759	bool "Use CFI in permissive mode"
760	depends on CFI_CLANG
761	help
762	  When selected, Control Flow Integrity (CFI) violations result in a
763	  warning instead of a kernel panic. This option should only be used
764	  for finding indirect call type mismatches during development.
765
766	  If unsure, say N.
767
768config HAVE_ARCH_WITHIN_STACK_FRAMES
769	bool
770	help
771	  An architecture should select this if it can walk the kernel stack
772	  frames to determine if an object is part of either the arguments
773	  or local variables (i.e. that it excludes saved return addresses,
774	  and similar) by implementing an inline arch_within_stack_frames(),
775	  which is used by CONFIG_HARDENED_USERCOPY.
776
777config HAVE_CONTEXT_TRACKING
778	bool
779	help
780	  Provide kernel/user boundaries probes necessary for subsystems
781	  that need it, such as userspace RCU extended quiescent state.
782	  Syscalls need to be wrapped inside user_exit()-user_enter(), either
783	  optimized behind static key or through the slow path using TIF_NOHZ
784	  flag. Exceptions handlers must be wrapped as well. Irqs are already
785	  protected inside rcu_irq_enter/rcu_irq_exit() but preemption or signal
786	  handling on irq exit still need to be protected.
787
788config HAVE_CONTEXT_TRACKING_OFFSTACK
789	bool
790	help
791	  Architecture neither relies on exception_enter()/exception_exit()
792	  nor on schedule_user(). Also preempt_schedule_notrace() and
793	  preempt_schedule_irq() can't be called in a preemptible section
794	  while context tracking is CONTEXT_USER. This feature reflects a sane
795	  entry implementation where the following requirements are met on
796	  critical entry code, ie: before user_exit() or after user_enter():
797
798	  - Critical entry code isn't preemptible (or better yet:
799	    not interruptible).
800	  - No use of RCU read side critical sections, unless rcu_nmi_enter()
801	    got called.
802	  - No use of instrumentation, unless instrumentation_begin() got
803	    called.
804
805config HAVE_TIF_NOHZ
806	bool
807	help
808	  Arch relies on TIF_NOHZ and syscall slow path to implement context
809	  tracking calls to user_enter()/user_exit().
810
811config HAVE_VIRT_CPU_ACCOUNTING
812	bool
813
814config HAVE_VIRT_CPU_ACCOUNTING_IDLE
815	bool
816	help
817	  Architecture has its own way to account idle CPU time and therefore
818	  doesn't implement vtime_account_idle().
819
820config ARCH_HAS_SCALED_CPUTIME
821	bool
822
823config HAVE_VIRT_CPU_ACCOUNTING_GEN
824	bool
825	default y if 64BIT
826	help
827	  With VIRT_CPU_ACCOUNTING_GEN, cputime_t becomes 64-bit.
828	  Before enabling this option, arch code must be audited
829	  to ensure there are no races in concurrent read/write of
830	  cputime_t. For example, reading/writing 64-bit cputime_t on
831	  some 32-bit arches may require multiple accesses, so proper
832	  locking is needed to protect against concurrent accesses.
833
834config HAVE_IRQ_TIME_ACCOUNTING
835	bool
836	help
837	  Archs need to ensure they use a high enough resolution clock to
838	  support irq time accounting and then call enable_sched_clock_irqtime().
839
840config HAVE_MOVE_PUD
841	bool
842	help
843	  Architectures that select this are able to move page tables at the
844	  PUD level. If there are only 3 page table levels, the move effectively
845	  happens at the PGD level.
846
847config HAVE_MOVE_PMD
848	bool
849	help
850	  Archs that select this are able to move page tables at the PMD level.
851
852config HAVE_ARCH_TRANSPARENT_HUGEPAGE
853	bool
854
855config HAVE_ARCH_TRANSPARENT_HUGEPAGE_PUD
856	bool
857
858config HAVE_ARCH_HUGE_VMAP
859	bool
860
861#
862#  Archs that select this would be capable of PMD-sized vmaps (i.e.,
863#  arch_vmap_pmd_supported() returns true). The VM_ALLOW_HUGE_VMAP flag
864#  must be used to enable allocations to use hugepages.
865#
866config HAVE_ARCH_HUGE_VMALLOC
867	depends on HAVE_ARCH_HUGE_VMAP
868	bool
869
870config ARCH_WANT_HUGE_PMD_SHARE
871	bool
872
873config HAVE_ARCH_SOFT_DIRTY
874	bool
875
876config HAVE_MOD_ARCH_SPECIFIC
877	bool
878	help
879	  The arch uses struct mod_arch_specific to store data.  Many arches
880	  just need a simple module loader without arch specific data - those
881	  should not enable this.
882
883config MODULES_USE_ELF_RELA
884	bool
885	help
886	  Modules only use ELF RELA relocations.  Modules with ELF REL
887	  relocations will give an error.
888
889config MODULES_USE_ELF_REL
890	bool
891	help
892	  Modules only use ELF REL relocations.  Modules with ELF RELA
893	  relocations will give an error.
894
895config HAVE_IRQ_EXIT_ON_IRQ_STACK
896	bool
897	help
898	  Architecture doesn't only execute the irq handler on the irq stack
899	  but also irq_exit(). This way we can process softirqs on this irq
900	  stack instead of switching to a new one when we call __do_softirq()
901	  in the end of an hardirq.
902	  This spares a stack switch and improves cache usage on softirq
903	  processing.
904
905config HAVE_SOFTIRQ_ON_OWN_STACK
906	bool
907	help
908	  Architecture provides a function to run __do_softirq() on a
909	  separate stack.
910
911config ALTERNATE_USER_ADDRESS_SPACE
912	bool
913	help
914	  Architectures set this when the CPU uses separate address
915	  spaces for kernel and user space pointers. In this case, the
916	  access_ok() check on a __user pointer is skipped.
917
918config PGTABLE_LEVELS
919	int
920	default 2
921
922config ARCH_HAS_ELF_RANDOMIZE
923	bool
924	help
925	  An architecture supports choosing randomized locations for
926	  stack, mmap, brk, and ET_DYN. Defined functions:
927	  - arch_mmap_rnd()
928	  - arch_randomize_brk()
929
930config HAVE_ARCH_MMAP_RND_BITS
931	bool
932	help
933	  An arch should select this symbol if it supports setting a variable
934	  number of bits for use in establishing the base address for mmap
935	  allocations, has MMU enabled and provides values for both:
936	  - ARCH_MMAP_RND_BITS_MIN
937	  - ARCH_MMAP_RND_BITS_MAX
938
939config HAVE_EXIT_THREAD
940	bool
941	help
942	  An architecture implements exit_thread.
943
944config ARCH_MMAP_RND_BITS_MIN
945	int
946
947config ARCH_MMAP_RND_BITS_MAX
948	int
949
950config ARCH_MMAP_RND_BITS_DEFAULT
951	int
952
953config ARCH_MMAP_RND_BITS
954	int "Number of bits to use for ASLR of mmap base address" if EXPERT
955	range ARCH_MMAP_RND_BITS_MIN ARCH_MMAP_RND_BITS_MAX
956	default ARCH_MMAP_RND_BITS_DEFAULT if ARCH_MMAP_RND_BITS_DEFAULT
957	default ARCH_MMAP_RND_BITS_MIN
958	depends on HAVE_ARCH_MMAP_RND_BITS
959	help
960	  This value can be used to select the number of bits to use to
961	  determine the random offset to the base address of vma regions
962	  resulting from mmap allocations. This value will be bounded
963	  by the architecture's minimum and maximum supported values.
964
965	  This value can be changed after boot using the
966	  /proc/sys/vm/mmap_rnd_bits tunable
967
968config HAVE_ARCH_MMAP_RND_COMPAT_BITS
969	bool
970	help
971	  An arch should select this symbol if it supports running applications
972	  in compatibility mode, supports setting a variable number of bits for
973	  use in establishing the base address for mmap allocations, has MMU
974	  enabled and provides values for both:
975	  - ARCH_MMAP_RND_COMPAT_BITS_MIN
976	  - ARCH_MMAP_RND_COMPAT_BITS_MAX
977
978config ARCH_MMAP_RND_COMPAT_BITS_MIN
979	int
980
981config ARCH_MMAP_RND_COMPAT_BITS_MAX
982	int
983
984config ARCH_MMAP_RND_COMPAT_BITS_DEFAULT
985	int
986
987config ARCH_MMAP_RND_COMPAT_BITS
988	int "Number of bits to use for ASLR of mmap base address for compatible applications" if EXPERT
989	range ARCH_MMAP_RND_COMPAT_BITS_MIN ARCH_MMAP_RND_COMPAT_BITS_MAX
990	default ARCH_MMAP_RND_COMPAT_BITS_DEFAULT if ARCH_MMAP_RND_COMPAT_BITS_DEFAULT
991	default ARCH_MMAP_RND_COMPAT_BITS_MIN
992	depends on HAVE_ARCH_MMAP_RND_COMPAT_BITS
993	help
994	  This value can be used to select the number of bits to use to
995	  determine the random offset to the base address of vma regions
996	  resulting from mmap allocations for compatible applications This
997	  value will be bounded by the architecture's minimum and maximum
998	  supported values.
999
1000	  This value can be changed after boot using the
1001	  /proc/sys/vm/mmap_rnd_compat_bits tunable
1002
1003config HAVE_ARCH_COMPAT_MMAP_BASES
1004	bool
1005	help
1006	  This allows 64bit applications to invoke 32-bit mmap() syscall
1007	  and vice-versa 32-bit applications to call 64-bit mmap().
1008	  Required for applications doing different bitness syscalls.
1009
1010config PAGE_SIZE_LESS_THAN_64KB
1011	def_bool y
1012	depends on !ARM64_64K_PAGES
1013	depends on !IA64_PAGE_SIZE_64KB
1014	depends on !PAGE_SIZE_64KB
1015	depends on !PARISC_PAGE_SIZE_64KB
1016	depends on !PPC_64K_PAGES
1017	depends on PAGE_SIZE_LESS_THAN_256KB
1018
1019config PAGE_SIZE_LESS_THAN_256KB
1020	def_bool y
1021	depends on !PPC_256K_PAGES
1022	depends on !PAGE_SIZE_256KB
1023
1024# This allows to use a set of generic functions to determine mmap base
1025# address by giving priority to top-down scheme only if the process
1026# is not in legacy mode (compat task, unlimited stack size or
1027# sysctl_legacy_va_layout).
1028# Architecture that selects this option can provide its own version of:
1029# - STACK_RND_MASK
1030config ARCH_WANT_DEFAULT_TOPDOWN_MMAP_LAYOUT
1031	bool
1032	depends on MMU
1033	select ARCH_HAS_ELF_RANDOMIZE
1034
1035config HAVE_OBJTOOL
1036	bool
1037
1038config HAVE_JUMP_LABEL_HACK
1039	bool
1040
1041config HAVE_NOINSTR_HACK
1042	bool
1043
1044config HAVE_NOINSTR_VALIDATION
1045	bool
1046
1047config HAVE_STACK_VALIDATION
1048	bool
1049	help
1050	  Architecture supports objtool compile-time frame pointer rule
1051	  validation.
1052
1053config HAVE_RELIABLE_STACKTRACE
1054	bool
1055	help
1056	  Architecture has either save_stack_trace_tsk_reliable() or
1057	  arch_stack_walk_reliable() function which only returns a stack trace
1058	  if it can guarantee the trace is reliable.
1059
1060config HAVE_ARCH_HASH
1061	bool
1062	default n
1063	help
1064	  If this is set, the architecture provides an <asm/hash.h>
1065	  file which provides platform-specific implementations of some
1066	  functions in <linux/hash.h> or fs/namei.c.
1067
1068config HAVE_ARCH_NVRAM_OPS
1069	bool
1070
1071config ISA_BUS_API
1072	def_bool ISA
1073
1074#
1075# ABI hall of shame
1076#
1077config CLONE_BACKWARDS
1078	bool
1079	help
1080	  Architecture has tls passed as the 4th argument of clone(2),
1081	  not the 5th one.
1082
1083config CLONE_BACKWARDS2
1084	bool
1085	help
1086	  Architecture has the first two arguments of clone(2) swapped.
1087
1088config CLONE_BACKWARDS3
1089	bool
1090	help
1091	  Architecture has tls passed as the 3rd argument of clone(2),
1092	  not the 5th one.
1093
1094config ODD_RT_SIGACTION
1095	bool
1096	help
1097	  Architecture has unusual rt_sigaction(2) arguments
1098
1099config OLD_SIGSUSPEND
1100	bool
1101	help
1102	  Architecture has old sigsuspend(2) syscall, of one-argument variety
1103
1104config OLD_SIGSUSPEND3
1105	bool
1106	help
1107	  Even weirder antique ABI - three-argument sigsuspend(2)
1108
1109config OLD_SIGACTION
1110	bool
1111	help
1112	  Architecture has old sigaction(2) syscall.  Nope, not the same
1113	  as OLD_SIGSUSPEND | OLD_SIGSUSPEND3 - alpha has sigsuspend(2),
1114	  but fairly different variant of sigaction(2), thanks to OSF/1
1115	  compatibility...
1116
1117config COMPAT_OLD_SIGACTION
1118	bool
1119
1120config COMPAT_32BIT_TIME
1121	bool "Provide system calls for 32-bit time_t"
1122	default !64BIT || COMPAT
1123	help
1124	  This enables 32 bit time_t support in addition to 64 bit time_t support.
1125	  This is relevant on all 32-bit architectures, and 64-bit architectures
1126	  as part of compat syscall handling.
1127
1128config ARCH_NO_PREEMPT
1129	bool
1130
1131config ARCH_EPHEMERAL_INODES
1132	def_bool n
1133	help
1134	  An arch should select this symbol if it doesn't keep track of inode
1135	  instances on its own, but instead relies on something else (e.g. the
1136	  host kernel for an UML kernel).
1137
1138config ARCH_SUPPORTS_RT
1139	bool
1140
1141config CPU_NO_EFFICIENT_FFS
1142	def_bool n
1143
1144config HAVE_ARCH_VMAP_STACK
1145	def_bool n
1146	help
1147	  An arch should select this symbol if it can support kernel stacks
1148	  in vmalloc space.  This means:
1149
1150	  - vmalloc space must be large enough to hold many kernel stacks.
1151	    This may rule out many 32-bit architectures.
1152
1153	  - Stacks in vmalloc space need to work reliably.  For example, if
1154	    vmap page tables are created on demand, either this mechanism
1155	    needs to work while the stack points to a virtual address with
1156	    unpopulated page tables or arch code (switch_to() and switch_mm(),
1157	    most likely) needs to ensure that the stack's page table entries
1158	    are populated before running on a possibly unpopulated stack.
1159
1160	  - If the stack overflows into a guard page, something reasonable
1161	    should happen.  The definition of "reasonable" is flexible, but
1162	    instantly rebooting without logging anything would be unfriendly.
1163
1164config VMAP_STACK
1165	default y
1166	bool "Use a virtually-mapped stack"
1167	depends on HAVE_ARCH_VMAP_STACK
1168	depends on !KASAN || KASAN_HW_TAGS || KASAN_VMALLOC
1169	help
1170	  Enable this if you want the use virtually-mapped kernel stacks
1171	  with guard pages.  This causes kernel stack overflows to be
1172	  caught immediately rather than causing difficult-to-diagnose
1173	  corruption.
1174
1175	  To use this with software KASAN modes, the architecture must support
1176	  backing virtual mappings with real shadow memory, and KASAN_VMALLOC
1177	  must be enabled.
1178
1179config HAVE_ARCH_RANDOMIZE_KSTACK_OFFSET
1180	def_bool n
1181	help
1182	  An arch should select this symbol if it can support kernel stack
1183	  offset randomization with calls to add_random_kstack_offset()
1184	  during syscall entry and choose_random_kstack_offset() during
1185	  syscall exit. Careful removal of -fstack-protector-strong and
1186	  -fstack-protector should also be applied to the entry code and
1187	  closely examined, as the artificial stack bump looks like an array
1188	  to the compiler, so it will attempt to add canary checks regardless
1189	  of the static branch state.
1190
1191config RANDOMIZE_KSTACK_OFFSET
1192	bool "Support for randomizing kernel stack offset on syscall entry" if EXPERT
1193	default y
1194	depends on HAVE_ARCH_RANDOMIZE_KSTACK_OFFSET
1195	depends on INIT_STACK_NONE || !CC_IS_CLANG || CLANG_VERSION >= 140000
1196	help
1197	  The kernel stack offset can be randomized (after pt_regs) by
1198	  roughly 5 bits of entropy, frustrating memory corruption
1199	  attacks that depend on stack address determinism or
1200	  cross-syscall address exposures.
1201
1202	  The feature is controlled via the "randomize_kstack_offset=on/off"
1203	  kernel boot param, and if turned off has zero overhead due to its use
1204	  of static branches (see JUMP_LABEL).
1205
1206	  If unsure, say Y.
1207
1208config RANDOMIZE_KSTACK_OFFSET_DEFAULT
1209	bool "Default state of kernel stack offset randomization"
1210	depends on RANDOMIZE_KSTACK_OFFSET
1211	help
1212	  Kernel stack offset randomization is controlled by kernel boot param
1213	  "randomize_kstack_offset=on/off", and this config chooses the default
1214	  boot state.
1215
1216config ARCH_OPTIONAL_KERNEL_RWX
1217	def_bool n
1218
1219config ARCH_OPTIONAL_KERNEL_RWX_DEFAULT
1220	def_bool n
1221
1222config ARCH_HAS_STRICT_KERNEL_RWX
1223	def_bool n
1224
1225config STRICT_KERNEL_RWX
1226	bool "Make kernel text and rodata read-only" if ARCH_OPTIONAL_KERNEL_RWX
1227	depends on ARCH_HAS_STRICT_KERNEL_RWX
1228	default !ARCH_OPTIONAL_KERNEL_RWX || ARCH_OPTIONAL_KERNEL_RWX_DEFAULT
1229	help
1230	  If this is set, kernel text and rodata memory will be made read-only,
1231	  and non-text memory will be made non-executable. This provides
1232	  protection against certain security exploits (e.g. executing the heap
1233	  or modifying text)
1234
1235	  These features are considered standard security practice these days.
1236	  You should say Y here in almost all cases.
1237
1238config ARCH_HAS_STRICT_MODULE_RWX
1239	def_bool n
1240
1241config STRICT_MODULE_RWX
1242	bool "Set loadable kernel module data as NX and text as RO" if ARCH_OPTIONAL_KERNEL_RWX
1243	depends on ARCH_HAS_STRICT_MODULE_RWX && MODULES
1244	default !ARCH_OPTIONAL_KERNEL_RWX || ARCH_OPTIONAL_KERNEL_RWX_DEFAULT
1245	help
1246	  If this is set, module text and rodata memory will be made read-only,
1247	  and non-text memory will be made non-executable. This provides
1248	  protection against certain security exploits (e.g. writing to text)
1249
1250# select if the architecture provides an asm/dma-direct.h header
1251config ARCH_HAS_PHYS_TO_DMA
1252	bool
1253
1254config HAVE_ARCH_COMPILER_H
1255	bool
1256	help
1257	  An architecture can select this if it provides an
1258	  asm/compiler.h header that should be included after
1259	  linux/compiler-*.h in order to override macro definitions that those
1260	  headers generally provide.
1261
1262config HAVE_ARCH_PREL32_RELOCATIONS
1263	bool
1264	help
1265	  May be selected by an architecture if it supports place-relative
1266	  32-bit relocations, both in the toolchain and in the module loader,
1267	  in which case relative references can be used in special sections
1268	  for PCI fixup, initcalls etc which are only half the size on 64 bit
1269	  architectures, and don't require runtime relocation on relocatable
1270	  kernels.
1271
1272config ARCH_USE_MEMREMAP_PROT
1273	bool
1274
1275config LOCK_EVENT_COUNTS
1276	bool "Locking event counts collection"
1277	depends on DEBUG_FS
1278	help
1279	  Enable light-weight counting of various locking related events
1280	  in the system with minimal performance impact. This reduces
1281	  the chance of application behavior change because of timing
1282	  differences. The counts are reported via debugfs.
1283
1284# Select if the architecture has support for applying RELR relocations.
1285config ARCH_HAS_RELR
1286	bool
1287
1288config RELR
1289	bool "Use RELR relocation packing"
1290	depends on ARCH_HAS_RELR && TOOLS_SUPPORT_RELR
1291	default y
1292	help
1293	  Store the kernel's dynamic relocations in the RELR relocation packing
1294	  format. Requires a compatible linker (LLD supports this feature), as
1295	  well as compatible NM and OBJCOPY utilities (llvm-nm and llvm-objcopy
1296	  are compatible).
1297
1298config ARCH_HAS_MEM_ENCRYPT
1299	bool
1300
1301config ARCH_HAS_CC_PLATFORM
1302	bool
1303
1304config HAVE_SPARSE_SYSCALL_NR
1305       bool
1306       help
1307          An architecture should select this if its syscall numbering is sparse
1308	  to save space. For example, MIPS architecture has a syscall array with
1309	  entries at 4000, 5000 and 6000 locations. This option turns on syscall
1310	  related optimizations for a given architecture.
1311
1312config ARCH_HAS_VDSO_DATA
1313	bool
1314
1315config HAVE_STATIC_CALL
1316	bool
1317
1318config HAVE_STATIC_CALL_INLINE
1319	bool
1320	depends on HAVE_STATIC_CALL
1321	select OBJTOOL
1322
1323config HAVE_PREEMPT_DYNAMIC
1324	bool
1325
1326config HAVE_PREEMPT_DYNAMIC_CALL
1327	bool
1328	depends on HAVE_STATIC_CALL
1329	select HAVE_PREEMPT_DYNAMIC
1330	help
1331	   An architecture should select this if it can handle the preemption
1332	   model being selected at boot time using static calls.
1333
1334	   Where an architecture selects HAVE_STATIC_CALL_INLINE, any call to a
1335	   preemption function will be patched directly.
1336
1337	   Where an architecture does not select HAVE_STATIC_CALL_INLINE, any
1338	   call to a preemption function will go through a trampoline, and the
1339	   trampoline will be patched.
1340
1341	   It is strongly advised to support inline static call to avoid any
1342	   overhead.
1343
1344config HAVE_PREEMPT_DYNAMIC_KEY
1345	bool
1346	depends on HAVE_ARCH_JUMP_LABEL && CC_HAS_ASM_GOTO
1347	select HAVE_PREEMPT_DYNAMIC
1348	help
1349	   An architecture should select this if it can handle the preemption
1350	   model being selected at boot time using static keys.
1351
1352	   Each preemption function will be given an early return based on a
1353	   static key. This should have slightly lower overhead than non-inline
1354	   static calls, as this effectively inlines each trampoline into the
1355	   start of its callee. This may avoid redundant work, and may
1356	   integrate better with CFI schemes.
1357
1358	   This will have greater overhead than using inline static calls as
1359	   the call to the preemption function cannot be entirely elided.
1360
1361config ARCH_WANT_LD_ORPHAN_WARN
1362	bool
1363	help
1364	  An arch should select this symbol once all linker sections are explicitly
1365	  included, size-asserted, or discarded in the linker scripts. This is
1366	  important because we never want expected sections to be placed heuristically
1367	  by the linker, since the locations of such sections can change between linker
1368	  versions.
1369
1370config HAVE_ARCH_PFN_VALID
1371	bool
1372
1373config ARCH_SUPPORTS_DEBUG_PAGEALLOC
1374	bool
1375
1376config ARCH_SUPPORTS_PAGE_TABLE_CHECK
1377	bool
1378
1379config ARCH_SPLIT_ARG64
1380	bool
1381	help
1382	   If a 32-bit architecture requires 64-bit arguments to be split into
1383	   pairs of 32-bit arguments, select this option.
1384
1385config ARCH_HAS_ELFCORE_COMPAT
1386	bool
1387
1388config ARCH_HAS_PARANOID_L1D_FLUSH
1389	bool
1390
1391config DYNAMIC_SIGFRAME
1392	bool
1393
1394# Select, if arch has a named attribute group bound to NUMA device nodes.
1395config HAVE_ARCH_NODE_DEV_GROUP
1396	bool
1397
1398source "kernel/gcov/Kconfig"
1399
1400source "scripts/gcc-plugins/Kconfig"
1401
1402endmenu
1403