xref: /openbmc/linux/arch/Kconfig (revision 5efb685b)
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	select OBJTOOL if HAVE_JUMP_LABEL_HACK
57	help
58	  This option enables a transparent branch optimization that
59	  makes certain almost-always-true or almost-always-false branch
60	  conditions even cheaper to execute within the kernel.
61
62	  Certain performance-sensitive kernel code, such as trace points,
63	  scheduler functionality, networking code and KVM have such
64	  branches and include support for this optimization technique.
65
66	  If it is detected that the compiler has support for "asm goto",
67	  the kernel will compile such branches with just a nop
68	  instruction. When the condition flag is toggled to true, the
69	  nop will be converted to a jump instruction to execute the
70	  conditional block of instructions.
71
72	  This technique lowers overhead and stress on the branch prediction
73	  of the processor and generally makes the kernel faster. The update
74	  of the condition is slower, but those are always very rare.
75
76	  ( On 32-bit x86, the necessary options added to the compiler
77	    flags may increase the size of the kernel slightly. )
78
79config STATIC_KEYS_SELFTEST
80	bool "Static key selftest"
81	depends on JUMP_LABEL
82	help
83	  Boot time self-test of the branch patching code.
84
85config STATIC_CALL_SELFTEST
86	bool "Static call selftest"
87	depends on HAVE_STATIC_CALL
88	help
89	  Boot time self-test of the call patching code.
90
91config OPTPROBES
92	def_bool y
93	depends on KPROBES && HAVE_OPTPROBES
94	select TASKS_RCU if PREEMPTION
95
96config KPROBES_ON_FTRACE
97	def_bool y
98	depends on KPROBES && HAVE_KPROBES_ON_FTRACE
99	depends on DYNAMIC_FTRACE_WITH_REGS
100	help
101	  If function tracer is enabled and the arch supports full
102	  passing of pt_regs to function tracing, then kprobes can
103	  optimize on top of function tracing.
104
105config UPROBES
106	def_bool n
107	depends on ARCH_SUPPORTS_UPROBES
108	help
109	  Uprobes is the user-space counterpart to kprobes: they
110	  enable instrumentation applications (such as 'perf probe')
111	  to establish unintrusive probes in user-space binaries and
112	  libraries, by executing handler functions when the probes
113	  are hit by user-space applications.
114
115	  ( These probes come in the form of single-byte breakpoints,
116	    managed by the kernel and kept transparent to the probed
117	    application. )
118
119config HAVE_64BIT_ALIGNED_ACCESS
120	def_bool 64BIT && !HAVE_EFFICIENT_UNALIGNED_ACCESS
121	help
122	  Some architectures require 64 bit accesses to be 64 bit
123	  aligned, which also requires structs containing 64 bit values
124	  to be 64 bit aligned too. This includes some 32 bit
125	  architectures which can do 64 bit accesses, as well as 64 bit
126	  architectures without unaligned access.
127
128	  This symbol should be selected by an architecture if 64 bit
129	  accesses are required to be 64 bit aligned in this way even
130	  though it is not a 64 bit architecture.
131
132	  See Documentation/core-api/unaligned-memory-access.rst for
133	  more information on the topic of unaligned memory accesses.
134
135config HAVE_EFFICIENT_UNALIGNED_ACCESS
136	bool
137	help
138	  Some architectures are unable to perform unaligned accesses
139	  without the use of get_unaligned/put_unaligned. Others are
140	  unable to perform such accesses efficiently (e.g. trap on
141	  unaligned access and require fixing it up in the exception
142	  handler.)
143
144	  This symbol should be selected by an architecture if it can
145	  perform unaligned accesses efficiently to allow different
146	  code paths to be selected for these cases. Some network
147	  drivers, for example, could opt to not fix up alignment
148	  problems with received packets if doing so would not help
149	  much.
150
151	  See Documentation/core-api/unaligned-memory-access.rst for more
152	  information on the topic of unaligned memory accesses.
153
154config ARCH_USE_BUILTIN_BSWAP
155	bool
156	help
157	  Modern versions of GCC (since 4.4) have builtin functions
158	  for handling byte-swapping. Using these, instead of the old
159	  inline assembler that the architecture code provides in the
160	  __arch_bswapXX() macros, allows the compiler to see what's
161	  happening and offers more opportunity for optimisation. In
162	  particular, the compiler will be able to combine the byteswap
163	  with a nearby load or store and use load-and-swap or
164	  store-and-swap instructions if the architecture has them. It
165	  should almost *never* result in code which is worse than the
166	  hand-coded assembler in <asm/swab.h>.  But just in case it
167	  does, the use of the builtins is optional.
168
169	  Any architecture with load-and-swap or store-and-swap
170	  instructions should set this. And it shouldn't hurt to set it
171	  on architectures that don't have such instructions.
172
173config KRETPROBES
174	def_bool y
175	depends on KPROBES && (HAVE_KRETPROBES || HAVE_RETHOOK)
176
177config KRETPROBE_ON_RETHOOK
178	def_bool y
179	depends on HAVE_RETHOOK
180	depends on KRETPROBES
181	select RETHOOK
182
183config USER_RETURN_NOTIFIER
184	bool
185	depends on HAVE_USER_RETURN_NOTIFIER
186	help
187	  Provide a kernel-internal notification when a cpu is about to
188	  switch to user mode.
189
190config HAVE_IOREMAP_PROT
191	bool
192
193config HAVE_KPROBES
194	bool
195
196config HAVE_KRETPROBES
197	bool
198
199config HAVE_OPTPROBES
200	bool
201
202config HAVE_KPROBES_ON_FTRACE
203	bool
204
205config ARCH_CORRECT_STACKTRACE_ON_KRETPROBE
206	bool
207	help
208	  Since kretprobes modifies return address on the stack, the
209	  stacktrace may see the kretprobe trampoline address instead
210	  of correct one. If the architecture stacktrace code and
211	  unwinder can adjust such entries, select this configuration.
212
213config HAVE_FUNCTION_ERROR_INJECTION
214	bool
215
216config HAVE_NMI
217	bool
218
219config HAVE_FUNCTION_DESCRIPTORS
220	bool
221
222config TRACE_IRQFLAGS_SUPPORT
223	bool
224
225config TRACE_IRQFLAGS_NMI_SUPPORT
226	bool
227
228#
229# An arch should select this if it provides all these things:
230#
231#	task_pt_regs()		in asm/processor.h or asm/ptrace.h
232#	arch_has_single_step()	if there is hardware single-step support
233#	arch_has_block_step()	if there is hardware block-step support
234#	asm/syscall.h		supplying asm-generic/syscall.h interface
235#	linux/regset.h		user_regset interfaces
236#	CORE_DUMP_USE_REGSET	#define'd in linux/elf.h
237#	TIF_SYSCALL_TRACE	calls ptrace_report_syscall_{entry,exit}
238#	TIF_NOTIFY_RESUME	calls resume_user_mode_work()
239#
240config HAVE_ARCH_TRACEHOOK
241	bool
242
243config HAVE_DMA_CONTIGUOUS
244	bool
245
246config GENERIC_SMP_IDLE_THREAD
247	bool
248
249config GENERIC_IDLE_POLL_SETUP
250	bool
251
252config ARCH_HAS_FORTIFY_SOURCE
253	bool
254	help
255	  An architecture should select this when it can successfully
256	  build and run with CONFIG_FORTIFY_SOURCE.
257
258#
259# Select if the arch provides a historic keepinit alias for the retain_initrd
260# command line option
261#
262config ARCH_HAS_KEEPINITRD
263	bool
264
265# Select if arch has all set_memory_ro/rw/x/nx() functions in asm/cacheflush.h
266config ARCH_HAS_SET_MEMORY
267	bool
268
269# Select if arch has all set_direct_map_invalid/default() functions
270config ARCH_HAS_SET_DIRECT_MAP
271	bool
272
273#
274# Select if the architecture provides the arch_dma_set_uncached symbol to
275# either provide an uncached segment alias for a DMA allocation, or
276# to remap the page tables in place.
277#
278config ARCH_HAS_DMA_SET_UNCACHED
279	bool
280
281#
282# Select if the architectures provides the arch_dma_clear_uncached symbol
283# to undo an in-place page table remap for uncached access.
284#
285config ARCH_HAS_DMA_CLEAR_UNCACHED
286	bool
287
288# Select if arch init_task must go in the __init_task_data section
289config ARCH_TASK_STRUCT_ON_STACK
290	bool
291
292# Select if arch has its private alloc_task_struct() function
293config ARCH_TASK_STRUCT_ALLOCATOR
294	bool
295
296config HAVE_ARCH_THREAD_STRUCT_WHITELIST
297	bool
298	depends on !ARCH_TASK_STRUCT_ALLOCATOR
299	help
300	  An architecture should select this to provide hardened usercopy
301	  knowledge about what region of the thread_struct should be
302	  whitelisted for copying to userspace. Normally this is only the
303	  FPU registers. Specifically, arch_thread_struct_whitelist()
304	  should be implemented. Without this, the entire thread_struct
305	  field in task_struct will be left whitelisted.
306
307# Select if arch has its private alloc_thread_stack() function
308config ARCH_THREAD_STACK_ALLOCATOR
309	bool
310
311# Select if arch wants to size task_struct dynamically via arch_task_struct_size:
312config ARCH_WANTS_DYNAMIC_TASK_STRUCT
313	bool
314
315config ARCH_WANTS_NO_INSTR
316	bool
317	help
318	  An architecture should select this if the noinstr macro is being used on
319	  functions to denote that the toolchain should avoid instrumenting such
320	  functions and is required for correctness.
321
322config ARCH_32BIT_OFF_T
323	bool
324	depends on !64BIT
325	help
326	  All new 32-bit architectures should have 64-bit off_t type on
327	  userspace side which corresponds to the loff_t kernel type. This
328	  is the requirement for modern ABIs. Some existing architectures
329	  still support 32-bit off_t. This option is enabled for all such
330	  architectures explicitly.
331
332# Selected by 64 bit architectures which have a 32 bit f_tinode in struct ustat
333config ARCH_32BIT_USTAT_F_TINODE
334	bool
335
336config HAVE_ASM_MODVERSIONS
337	bool
338	help
339	  This symbol should be selected by an architecture if it provides
340	  <asm/asm-prototypes.h> to support the module versioning for symbols
341	  exported from assembly code.
342
343config HAVE_REGS_AND_STACK_ACCESS_API
344	bool
345	help
346	  This symbol should be selected by an architecture if it supports
347	  the API needed to access registers and stack entries from pt_regs,
348	  declared in asm/ptrace.h
349	  For example the kprobes-based event tracer needs this API.
350
351config HAVE_RSEQ
352	bool
353	depends on HAVE_REGS_AND_STACK_ACCESS_API
354	help
355	  This symbol should be selected by an architecture if it
356	  supports an implementation of restartable sequences.
357
358config HAVE_RUST
359	bool
360	help
361	  This symbol should be selected by an architecture if it
362	  supports Rust.
363
364config HAVE_FUNCTION_ARG_ACCESS_API
365	bool
366	help
367	  This symbol should be selected by an architecture if it supports
368	  the API needed to access function arguments from pt_regs,
369	  declared in asm/ptrace.h
370
371config HAVE_HW_BREAKPOINT
372	bool
373	depends on PERF_EVENTS
374
375config HAVE_MIXED_BREAKPOINTS_REGS
376	bool
377	depends on HAVE_HW_BREAKPOINT
378	help
379	  Depending on the arch implementation of hardware breakpoints,
380	  some of them have separate registers for data and instruction
381	  breakpoints addresses, others have mixed registers to store
382	  them but define the access type in a control register.
383	  Select this option if your arch implements breakpoints under the
384	  latter fashion.
385
386config HAVE_USER_RETURN_NOTIFIER
387	bool
388
389config HAVE_PERF_EVENTS_NMI
390	bool
391	help
392	  System hardware can generate an NMI using the perf event
393	  subsystem.  Also has support for calculating CPU cycle events
394	  to determine how many clock cycles in a given period.
395
396config HAVE_HARDLOCKUP_DETECTOR_PERF
397	bool
398	depends on HAVE_PERF_EVENTS_NMI
399	help
400	  The arch chooses to use the generic perf-NMI-based hardlockup
401	  detector. Must define HAVE_PERF_EVENTS_NMI.
402
403config HAVE_NMI_WATCHDOG
404	depends on HAVE_NMI
405	bool
406	help
407	  The arch provides a low level NMI watchdog. It provides
408	  asm/nmi.h, and defines its own arch_touch_nmi_watchdog().
409
410config HAVE_HARDLOCKUP_DETECTOR_ARCH
411	bool
412	select HAVE_NMI_WATCHDOG
413	help
414	  The arch chooses to provide its own hardlockup detector, which is
415	  a superset of the HAVE_NMI_WATCHDOG. It also conforms to config
416	  interfaces and parameters provided by hardlockup detector subsystem.
417
418config HAVE_PERF_REGS
419	bool
420	help
421	  Support selective register dumps for perf events. This includes
422	  bit-mapping of each registers and a unique architecture id.
423
424config HAVE_PERF_USER_STACK_DUMP
425	bool
426	help
427	  Support user stack dumps for perf event samples. This needs
428	  access to the user stack pointer which is not unified across
429	  architectures.
430
431config HAVE_ARCH_JUMP_LABEL
432	bool
433
434config HAVE_ARCH_JUMP_LABEL_RELATIVE
435	bool
436
437config MMU_GATHER_TABLE_FREE
438	bool
439
440config MMU_GATHER_RCU_TABLE_FREE
441	bool
442	select MMU_GATHER_TABLE_FREE
443
444config MMU_GATHER_PAGE_SIZE
445	bool
446
447config MMU_GATHER_NO_RANGE
448	bool
449	select MMU_GATHER_MERGE_VMAS
450
451config MMU_GATHER_NO_FLUSH_CACHE
452	bool
453
454config MMU_GATHER_MERGE_VMAS
455	bool
456
457config MMU_GATHER_NO_GATHER
458	bool
459	depends on MMU_GATHER_TABLE_FREE
460
461config ARCH_WANT_IRQS_OFF_ACTIVATE_MM
462	bool
463	help
464	  Temporary select until all architectures can be converted to have
465	  irqs disabled over activate_mm. Architectures that do IPI based TLB
466	  shootdowns should enable this.
467
468config ARCH_HAVE_NMI_SAFE_CMPXCHG
469	bool
470
471config ARCH_HAS_NMI_SAFE_THIS_CPU_OPS
472	bool
473
474config HAVE_ALIGNED_STRUCT_PAGE
475	bool
476	help
477	  This makes sure that struct pages are double word aligned and that
478	  e.g. the SLUB allocator can perform double word atomic operations
479	  on a struct page for better performance. However selecting this
480	  might increase the size of a struct page by a word.
481
482config HAVE_CMPXCHG_LOCAL
483	bool
484
485config HAVE_CMPXCHG_DOUBLE
486	bool
487
488config ARCH_WEAK_RELEASE_ACQUIRE
489	bool
490
491config ARCH_WANT_IPC_PARSE_VERSION
492	bool
493
494config ARCH_WANT_COMPAT_IPC_PARSE_VERSION
495	bool
496
497config ARCH_WANT_OLD_COMPAT_IPC
498	select ARCH_WANT_COMPAT_IPC_PARSE_VERSION
499	bool
500
501config HAVE_ARCH_SECCOMP
502	bool
503	help
504	  An arch should select this symbol to support seccomp mode 1 (the fixed
505	  syscall policy), and must provide an overrides for __NR_seccomp_sigreturn,
506	  and compat syscalls if the asm-generic/seccomp.h defaults need adjustment:
507	  - __NR_seccomp_read_32
508	  - __NR_seccomp_write_32
509	  - __NR_seccomp_exit_32
510	  - __NR_seccomp_sigreturn_32
511
512config HAVE_ARCH_SECCOMP_FILTER
513	bool
514	select HAVE_ARCH_SECCOMP
515	help
516	  An arch should select this symbol if it provides all of these things:
517	  - all the requirements for HAVE_ARCH_SECCOMP
518	  - syscall_get_arch()
519	  - syscall_get_arguments()
520	  - syscall_rollback()
521	  - syscall_set_return_value()
522	  - SIGSYS siginfo_t support
523	  - secure_computing is called from a ptrace_event()-safe context
524	  - secure_computing return value is checked and a return value of -1
525	    results in the system call being skipped immediately.
526	  - seccomp syscall wired up
527	  - if !HAVE_SPARSE_SYSCALL_NR, have SECCOMP_ARCH_NATIVE,
528	    SECCOMP_ARCH_NATIVE_NR, SECCOMP_ARCH_NATIVE_NAME defined. If
529	    COMPAT is supported, have the SECCOMP_ARCH_COMPAT* defines too.
530
531config SECCOMP
532	prompt "Enable seccomp to safely execute untrusted bytecode"
533	def_bool y
534	depends on HAVE_ARCH_SECCOMP
535	help
536	  This kernel feature is useful for number crunching applications
537	  that may need to handle untrusted bytecode during their
538	  execution. By using pipes or other transports made available
539	  to the process as file descriptors supporting the read/write
540	  syscalls, it's possible to isolate those applications in their
541	  own address space using seccomp. Once seccomp is enabled via
542	  prctl(PR_SET_SECCOMP) or the seccomp() syscall, it cannot be
543	  disabled and the task is only allowed to execute a few safe
544	  syscalls defined by each seccomp mode.
545
546	  If unsure, say Y.
547
548config SECCOMP_FILTER
549	def_bool y
550	depends on HAVE_ARCH_SECCOMP_FILTER && SECCOMP && NET
551	help
552	  Enable tasks to build secure computing environments defined
553	  in terms of Berkeley Packet Filter programs which implement
554	  task-defined system call filtering polices.
555
556	  See Documentation/userspace-api/seccomp_filter.rst for details.
557
558config SECCOMP_CACHE_DEBUG
559	bool "Show seccomp filter cache status in /proc/pid/seccomp_cache"
560	depends on SECCOMP_FILTER && !HAVE_SPARSE_SYSCALL_NR
561	depends on PROC_FS
562	help
563	  This enables the /proc/pid/seccomp_cache interface to monitor
564	  seccomp cache data. The file format is subject to change. Reading
565	  the file requires CAP_SYS_ADMIN.
566
567	  This option is for debugging only. Enabling presents the risk that
568	  an adversary may be able to infer the seccomp filter logic.
569
570	  If unsure, say N.
571
572config HAVE_ARCH_STACKLEAK
573	bool
574	help
575	  An architecture should select this if it has the code which
576	  fills the used part of the kernel stack with the STACKLEAK_POISON
577	  value before returning from system calls.
578
579config HAVE_STACKPROTECTOR
580	bool
581	help
582	  An arch should select this symbol if:
583	  - it has implemented a stack canary (e.g. __stack_chk_guard)
584
585config STACKPROTECTOR
586	bool "Stack Protector buffer overflow detection"
587	depends on HAVE_STACKPROTECTOR
588	depends on $(cc-option,-fstack-protector)
589	default y
590	help
591	  This option turns on the "stack-protector" GCC feature. This
592	  feature puts, at the beginning of functions, a canary value on
593	  the stack just before the return address, and validates
594	  the value just before actually returning.  Stack based buffer
595	  overflows (that need to overwrite this return address) now also
596	  overwrite the canary, which gets detected and the attack is then
597	  neutralized via a kernel panic.
598
599	  Functions will have the stack-protector canary logic added if they
600	  have an 8-byte or larger character array on the stack.
601
602	  This feature requires gcc version 4.2 or above, or a distribution
603	  gcc with the feature backported ("-fstack-protector").
604
605	  On an x86 "defconfig" build, this feature adds canary checks to
606	  about 3% of all kernel functions, which increases kernel code size
607	  by about 0.3%.
608
609config STACKPROTECTOR_STRONG
610	bool "Strong Stack Protector"
611	depends on STACKPROTECTOR
612	depends on $(cc-option,-fstack-protector-strong)
613	default y
614	help
615	  Functions will have the stack-protector canary logic added in any
616	  of the following conditions:
617
618	  - local variable's address used as part of the right hand side of an
619	    assignment or function argument
620	  - local variable is an array (or union containing an array),
621	    regardless of array type or length
622	  - uses register local variables
623
624	  This feature requires gcc version 4.9 or above, or a distribution
625	  gcc with the feature backported ("-fstack-protector-strong").
626
627	  On an x86 "defconfig" build, this feature adds canary checks to
628	  about 20% of all kernel functions, which increases the kernel code
629	  size by about 2%.
630
631config ARCH_SUPPORTS_SHADOW_CALL_STACK
632	bool
633	help
634	  An architecture should select this if it supports the compiler's
635	  Shadow Call Stack and implements runtime support for shadow stack
636	  switching.
637
638config SHADOW_CALL_STACK
639	bool "Shadow Call Stack"
640	depends on ARCH_SUPPORTS_SHADOW_CALL_STACK
641	depends on DYNAMIC_FTRACE_WITH_ARGS || DYNAMIC_FTRACE_WITH_REGS || !FUNCTION_GRAPH_TRACER
642	help
643	  This option enables the compiler's Shadow Call Stack, which
644	  uses a shadow stack to protect function return addresses from
645	  being overwritten by an attacker. More information can be found
646	  in the compiler's documentation:
647
648	  - Clang: https://clang.llvm.org/docs/ShadowCallStack.html
649	  - GCC: https://gcc.gnu.org/onlinedocs/gcc/Instrumentation-Options.html#Instrumentation-Options
650
651	  Note that security guarantees in the kernel differ from the
652	  ones documented for user space. The kernel must store addresses
653	  of shadow stacks in memory, which means an attacker capable of
654	  reading and writing arbitrary memory may be able to locate them
655	  and hijack control flow by modifying the stacks.
656
657config DYNAMIC_SCS
658	bool
659	help
660	  Set by the arch code if it relies on code patching to insert the
661	  shadow call stack push and pop instructions rather than on the
662	  compiler.
663
664config LTO
665	bool
666	help
667	  Selected if the kernel will be built using the compiler's LTO feature.
668
669config LTO_CLANG
670	bool
671	select LTO
672	help
673	  Selected if the kernel will be built using Clang's LTO feature.
674
675config ARCH_SUPPORTS_LTO_CLANG
676	bool
677	help
678	  An architecture should select this option if it supports:
679	  - compiling with Clang,
680	  - compiling inline assembly with Clang's integrated assembler,
681	  - and linking with LLD.
682
683config ARCH_SUPPORTS_LTO_CLANG_THIN
684	bool
685	help
686	  An architecture should select this option if it can support Clang's
687	  ThinLTO mode.
688
689config HAS_LTO_CLANG
690	def_bool y
691	depends on CC_IS_CLANG && LD_IS_LLD && AS_IS_LLVM
692	depends on $(success,$(NM) --help | head -n 1 | grep -qi llvm)
693	depends on $(success,$(AR) --help | head -n 1 | grep -qi llvm)
694	depends on ARCH_SUPPORTS_LTO_CLANG
695	depends on !FTRACE_MCOUNT_USE_RECORDMCOUNT
696	depends on !KASAN || KASAN_HW_TAGS
697	depends on !GCOV_KERNEL
698	help
699	  The compiler and Kconfig options support building with Clang's
700	  LTO.
701
702choice
703	prompt "Link Time Optimization (LTO)"
704	default LTO_NONE
705	help
706	  This option enables Link Time Optimization (LTO), which allows the
707	  compiler to optimize binaries globally.
708
709	  If unsure, select LTO_NONE. Note that LTO is very resource-intensive
710	  so it's disabled by default.
711
712config LTO_NONE
713	bool "None"
714	help
715	  Build the kernel normally, without Link Time Optimization (LTO).
716
717config LTO_CLANG_FULL
718	bool "Clang Full LTO (EXPERIMENTAL)"
719	depends on HAS_LTO_CLANG
720	depends on !COMPILE_TEST
721	select LTO_CLANG
722	help
723	  This option enables Clang's full Link Time Optimization (LTO), which
724	  allows the compiler to optimize the kernel globally. If you enable
725	  this option, the compiler generates LLVM bitcode instead of ELF
726	  object files, and the actual compilation from bitcode happens at
727	  the LTO link step, which may take several minutes depending on the
728	  kernel configuration. More information can be found from LLVM's
729	  documentation:
730
731	    https://llvm.org/docs/LinkTimeOptimization.html
732
733	  During link time, this option can use a large amount of RAM, and
734	  may take much longer than the ThinLTO option.
735
736config LTO_CLANG_THIN
737	bool "Clang ThinLTO (EXPERIMENTAL)"
738	depends on HAS_LTO_CLANG && ARCH_SUPPORTS_LTO_CLANG_THIN
739	select LTO_CLANG
740	help
741	  This option enables Clang's ThinLTO, which allows for parallel
742	  optimization and faster incremental compiles compared to the
743	  CONFIG_LTO_CLANG_FULL option. More information can be found
744	  from Clang's documentation:
745
746	    https://clang.llvm.org/docs/ThinLTO.html
747
748	  If unsure, say Y.
749endchoice
750
751config ARCH_SUPPORTS_CFI_CLANG
752	bool
753	help
754	  An architecture should select this option if it can support Clang's
755	  Control-Flow Integrity (CFI) checking.
756
757config ARCH_USES_CFI_TRAPS
758	bool
759
760config CFI_CLANG
761	bool "Use Clang's Control Flow Integrity (CFI)"
762	depends on ARCH_SUPPORTS_CFI_CLANG
763	depends on $(cc-option,-fsanitize=kcfi)
764	help
765	  This option enables Clang’s forward-edge Control Flow Integrity
766	  (CFI) checking, where the compiler injects a runtime check to each
767	  indirect function call to ensure the target is a valid function with
768	  the correct static type. This restricts possible call targets and
769	  makes it more difficult for an attacker to exploit bugs that allow
770	  the modification of stored function pointers. More information can be
771	  found from Clang's documentation:
772
773	    https://clang.llvm.org/docs/ControlFlowIntegrity.html
774
775config CFI_PERMISSIVE
776	bool "Use CFI in permissive mode"
777	depends on CFI_CLANG
778	help
779	  When selected, Control Flow Integrity (CFI) violations result in a
780	  warning instead of a kernel panic. This option should only be used
781	  for finding indirect call type mismatches during development.
782
783	  If unsure, say N.
784
785config HAVE_ARCH_WITHIN_STACK_FRAMES
786	bool
787	help
788	  An architecture should select this if it can walk the kernel stack
789	  frames to determine if an object is part of either the arguments
790	  or local variables (i.e. that it excludes saved return addresses,
791	  and similar) by implementing an inline arch_within_stack_frames(),
792	  which is used by CONFIG_HARDENED_USERCOPY.
793
794config HAVE_CONTEXT_TRACKING_USER
795	bool
796	help
797	  Provide kernel/user boundaries probes necessary for subsystems
798	  that need it, such as userspace RCU extended quiescent state.
799	  Syscalls need to be wrapped inside user_exit()-user_enter(), either
800	  optimized behind static key or through the slow path using TIF_NOHZ
801	  flag. Exceptions handlers must be wrapped as well. Irqs are already
802	  protected inside ct_irq_enter/ct_irq_exit() but preemption or signal
803	  handling on irq exit still need to be protected.
804
805config HAVE_CONTEXT_TRACKING_USER_OFFSTACK
806	bool
807	help
808	  Architecture neither relies on exception_enter()/exception_exit()
809	  nor on schedule_user(). Also preempt_schedule_notrace() and
810	  preempt_schedule_irq() can't be called in a preemptible section
811	  while context tracking is CONTEXT_USER. This feature reflects a sane
812	  entry implementation where the following requirements are met on
813	  critical entry code, ie: before user_exit() or after user_enter():
814
815	  - Critical entry code isn't preemptible (or better yet:
816	    not interruptible).
817	  - No use of RCU read side critical sections, unless ct_nmi_enter()
818	    got called.
819	  - No use of instrumentation, unless instrumentation_begin() got
820	    called.
821
822config HAVE_TIF_NOHZ
823	bool
824	help
825	  Arch relies on TIF_NOHZ and syscall slow path to implement context
826	  tracking calls to user_enter()/user_exit().
827
828config HAVE_VIRT_CPU_ACCOUNTING
829	bool
830
831config HAVE_VIRT_CPU_ACCOUNTING_IDLE
832	bool
833	help
834	  Architecture has its own way to account idle CPU time and therefore
835	  doesn't implement vtime_account_idle().
836
837config ARCH_HAS_SCALED_CPUTIME
838	bool
839
840config HAVE_VIRT_CPU_ACCOUNTING_GEN
841	bool
842	default y if 64BIT
843	help
844	  With VIRT_CPU_ACCOUNTING_GEN, cputime_t becomes 64-bit.
845	  Before enabling this option, arch code must be audited
846	  to ensure there are no races in concurrent read/write of
847	  cputime_t. For example, reading/writing 64-bit cputime_t on
848	  some 32-bit arches may require multiple accesses, so proper
849	  locking is needed to protect against concurrent accesses.
850
851config HAVE_IRQ_TIME_ACCOUNTING
852	bool
853	help
854	  Archs need to ensure they use a high enough resolution clock to
855	  support irq time accounting and then call enable_sched_clock_irqtime().
856
857config HAVE_MOVE_PUD
858	bool
859	help
860	  Architectures that select this are able to move page tables at the
861	  PUD level. If there are only 3 page table levels, the move effectively
862	  happens at the PGD level.
863
864config HAVE_MOVE_PMD
865	bool
866	help
867	  Archs that select this are able to move page tables at the PMD level.
868
869config HAVE_ARCH_TRANSPARENT_HUGEPAGE
870	bool
871
872config HAVE_ARCH_TRANSPARENT_HUGEPAGE_PUD
873	bool
874
875config HAVE_ARCH_HUGE_VMAP
876	bool
877
878#
879#  Archs that select this would be capable of PMD-sized vmaps (i.e.,
880#  arch_vmap_pmd_supported() returns true). The VM_ALLOW_HUGE_VMAP flag
881#  must be used to enable allocations to use hugepages.
882#
883config HAVE_ARCH_HUGE_VMALLOC
884	depends on HAVE_ARCH_HUGE_VMAP
885	bool
886
887config ARCH_WANT_HUGE_PMD_SHARE
888	bool
889
890config HAVE_ARCH_SOFT_DIRTY
891	bool
892
893config HAVE_MOD_ARCH_SPECIFIC
894	bool
895	help
896	  The arch uses struct mod_arch_specific to store data.  Many arches
897	  just need a simple module loader without arch specific data - those
898	  should not enable this.
899
900config MODULES_USE_ELF_RELA
901	bool
902	help
903	  Modules only use ELF RELA relocations.  Modules with ELF REL
904	  relocations will give an error.
905
906config MODULES_USE_ELF_REL
907	bool
908	help
909	  Modules only use ELF REL relocations.  Modules with ELF RELA
910	  relocations will give an error.
911
912config ARCH_WANTS_MODULES_DATA_IN_VMALLOC
913	bool
914	help
915	  For architectures like powerpc/32 which have constraints on module
916	  allocation and need to allocate module data outside of module area.
917
918config HAVE_IRQ_EXIT_ON_IRQ_STACK
919	bool
920	help
921	  Architecture doesn't only execute the irq handler on the irq stack
922	  but also irq_exit(). This way we can process softirqs on this irq
923	  stack instead of switching to a new one when we call __do_softirq()
924	  in the end of an hardirq.
925	  This spares a stack switch and improves cache usage on softirq
926	  processing.
927
928config HAVE_SOFTIRQ_ON_OWN_STACK
929	bool
930	help
931	  Architecture provides a function to run __do_softirq() on a
932	  separate stack.
933
934config SOFTIRQ_ON_OWN_STACK
935	def_bool HAVE_SOFTIRQ_ON_OWN_STACK && !PREEMPT_RT
936
937config ALTERNATE_USER_ADDRESS_SPACE
938	bool
939	help
940	  Architectures set this when the CPU uses separate address
941	  spaces for kernel and user space pointers. In this case, the
942	  access_ok() check on a __user pointer is skipped.
943
944config PGTABLE_LEVELS
945	int
946	default 2
947
948config ARCH_HAS_ELF_RANDOMIZE
949	bool
950	help
951	  An architecture supports choosing randomized locations for
952	  stack, mmap, brk, and ET_DYN. Defined functions:
953	  - arch_mmap_rnd()
954	  - arch_randomize_brk()
955
956config HAVE_ARCH_MMAP_RND_BITS
957	bool
958	help
959	  An arch should select this symbol if it supports setting a variable
960	  number of bits for use in establishing the base address for mmap
961	  allocations, has MMU enabled and provides values for both:
962	  - ARCH_MMAP_RND_BITS_MIN
963	  - ARCH_MMAP_RND_BITS_MAX
964
965config HAVE_EXIT_THREAD
966	bool
967	help
968	  An architecture implements exit_thread.
969
970config ARCH_MMAP_RND_BITS_MIN
971	int
972
973config ARCH_MMAP_RND_BITS_MAX
974	int
975
976config ARCH_MMAP_RND_BITS_DEFAULT
977	int
978
979config ARCH_MMAP_RND_BITS
980	int "Number of bits to use for ASLR of mmap base address" if EXPERT
981	range ARCH_MMAP_RND_BITS_MIN ARCH_MMAP_RND_BITS_MAX
982	default ARCH_MMAP_RND_BITS_DEFAULT if ARCH_MMAP_RND_BITS_DEFAULT
983	default ARCH_MMAP_RND_BITS_MIN
984	depends on HAVE_ARCH_MMAP_RND_BITS
985	help
986	  This value can be used to select the number of bits to use to
987	  determine the random offset to the base address of vma regions
988	  resulting from mmap allocations. This value will be bounded
989	  by the architecture's minimum and maximum supported values.
990
991	  This value can be changed after boot using the
992	  /proc/sys/vm/mmap_rnd_bits tunable
993
994config HAVE_ARCH_MMAP_RND_COMPAT_BITS
995	bool
996	help
997	  An arch should select this symbol if it supports running applications
998	  in compatibility mode, supports setting a variable number of bits for
999	  use in establishing the base address for mmap allocations, has MMU
1000	  enabled and provides values for both:
1001	  - ARCH_MMAP_RND_COMPAT_BITS_MIN
1002	  - ARCH_MMAP_RND_COMPAT_BITS_MAX
1003
1004config ARCH_MMAP_RND_COMPAT_BITS_MIN
1005	int
1006
1007config ARCH_MMAP_RND_COMPAT_BITS_MAX
1008	int
1009
1010config ARCH_MMAP_RND_COMPAT_BITS_DEFAULT
1011	int
1012
1013config ARCH_MMAP_RND_COMPAT_BITS
1014	int "Number of bits to use for ASLR of mmap base address for compatible applications" if EXPERT
1015	range ARCH_MMAP_RND_COMPAT_BITS_MIN ARCH_MMAP_RND_COMPAT_BITS_MAX
1016	default ARCH_MMAP_RND_COMPAT_BITS_DEFAULT if ARCH_MMAP_RND_COMPAT_BITS_DEFAULT
1017	default ARCH_MMAP_RND_COMPAT_BITS_MIN
1018	depends on HAVE_ARCH_MMAP_RND_COMPAT_BITS
1019	help
1020	  This value can be used to select the number of bits to use to
1021	  determine the random offset to the base address of vma regions
1022	  resulting from mmap allocations for compatible applications This
1023	  value will be bounded by the architecture's minimum and maximum
1024	  supported values.
1025
1026	  This value can be changed after boot using the
1027	  /proc/sys/vm/mmap_rnd_compat_bits tunable
1028
1029config HAVE_ARCH_COMPAT_MMAP_BASES
1030	bool
1031	help
1032	  This allows 64bit applications to invoke 32-bit mmap() syscall
1033	  and vice-versa 32-bit applications to call 64-bit mmap().
1034	  Required for applications doing different bitness syscalls.
1035
1036config PAGE_SIZE_LESS_THAN_64KB
1037	def_bool y
1038	depends on !ARM64_64K_PAGES
1039	depends on !IA64_PAGE_SIZE_64KB
1040	depends on !PAGE_SIZE_64KB
1041	depends on !PARISC_PAGE_SIZE_64KB
1042	depends on PAGE_SIZE_LESS_THAN_256KB
1043
1044config PAGE_SIZE_LESS_THAN_256KB
1045	def_bool y
1046	depends on !PAGE_SIZE_256KB
1047
1048# This allows to use a set of generic functions to determine mmap base
1049# address by giving priority to top-down scheme only if the process
1050# is not in legacy mode (compat task, unlimited stack size or
1051# sysctl_legacy_va_layout).
1052# Architecture that selects this option can provide its own version of:
1053# - STACK_RND_MASK
1054config ARCH_WANT_DEFAULT_TOPDOWN_MMAP_LAYOUT
1055	bool
1056	depends on MMU
1057	select ARCH_HAS_ELF_RANDOMIZE
1058
1059config HAVE_OBJTOOL
1060	bool
1061
1062config HAVE_JUMP_LABEL_HACK
1063	bool
1064
1065config HAVE_NOINSTR_HACK
1066	bool
1067
1068config HAVE_NOINSTR_VALIDATION
1069	bool
1070
1071config HAVE_UACCESS_VALIDATION
1072	bool
1073	select OBJTOOL
1074
1075config HAVE_STACK_VALIDATION
1076	bool
1077	help
1078	  Architecture supports objtool compile-time frame pointer rule
1079	  validation.
1080
1081config HAVE_RELIABLE_STACKTRACE
1082	bool
1083	help
1084	  Architecture has either save_stack_trace_tsk_reliable() or
1085	  arch_stack_walk_reliable() function which only returns a stack trace
1086	  if it can guarantee the trace is reliable.
1087
1088config HAVE_ARCH_HASH
1089	bool
1090	default n
1091	help
1092	  If this is set, the architecture provides an <asm/hash.h>
1093	  file which provides platform-specific implementations of some
1094	  functions in <linux/hash.h> or fs/namei.c.
1095
1096config HAVE_ARCH_NVRAM_OPS
1097	bool
1098
1099config ISA_BUS_API
1100	def_bool ISA
1101
1102#
1103# ABI hall of shame
1104#
1105config CLONE_BACKWARDS
1106	bool
1107	help
1108	  Architecture has tls passed as the 4th argument of clone(2),
1109	  not the 5th one.
1110
1111config CLONE_BACKWARDS2
1112	bool
1113	help
1114	  Architecture has the first two arguments of clone(2) swapped.
1115
1116config CLONE_BACKWARDS3
1117	bool
1118	help
1119	  Architecture has tls passed as the 3rd argument of clone(2),
1120	  not the 5th one.
1121
1122config ODD_RT_SIGACTION
1123	bool
1124	help
1125	  Architecture has unusual rt_sigaction(2) arguments
1126
1127config OLD_SIGSUSPEND
1128	bool
1129	help
1130	  Architecture has old sigsuspend(2) syscall, of one-argument variety
1131
1132config OLD_SIGSUSPEND3
1133	bool
1134	help
1135	  Even weirder antique ABI - three-argument sigsuspend(2)
1136
1137config OLD_SIGACTION
1138	bool
1139	help
1140	  Architecture has old sigaction(2) syscall.  Nope, not the same
1141	  as OLD_SIGSUSPEND | OLD_SIGSUSPEND3 - alpha has sigsuspend(2),
1142	  but fairly different variant of sigaction(2), thanks to OSF/1
1143	  compatibility...
1144
1145config COMPAT_OLD_SIGACTION
1146	bool
1147
1148config COMPAT_32BIT_TIME
1149	bool "Provide system calls for 32-bit time_t"
1150	default !64BIT || COMPAT
1151	help
1152	  This enables 32 bit time_t support in addition to 64 bit time_t support.
1153	  This is relevant on all 32-bit architectures, and 64-bit architectures
1154	  as part of compat syscall handling.
1155
1156config ARCH_NO_PREEMPT
1157	bool
1158
1159config ARCH_EPHEMERAL_INODES
1160	def_bool n
1161	help
1162	  An arch should select this symbol if it doesn't keep track of inode
1163	  instances on its own, but instead relies on something else (e.g. the
1164	  host kernel for an UML kernel).
1165
1166config ARCH_SUPPORTS_RT
1167	bool
1168
1169config CPU_NO_EFFICIENT_FFS
1170	def_bool n
1171
1172config HAVE_ARCH_VMAP_STACK
1173	def_bool n
1174	help
1175	  An arch should select this symbol if it can support kernel stacks
1176	  in vmalloc space.  This means:
1177
1178	  - vmalloc space must be large enough to hold many kernel stacks.
1179	    This may rule out many 32-bit architectures.
1180
1181	  - Stacks in vmalloc space need to work reliably.  For example, if
1182	    vmap page tables are created on demand, either this mechanism
1183	    needs to work while the stack points to a virtual address with
1184	    unpopulated page tables or arch code (switch_to() and switch_mm(),
1185	    most likely) needs to ensure that the stack's page table entries
1186	    are populated before running on a possibly unpopulated stack.
1187
1188	  - If the stack overflows into a guard page, something reasonable
1189	    should happen.  The definition of "reasonable" is flexible, but
1190	    instantly rebooting without logging anything would be unfriendly.
1191
1192config VMAP_STACK
1193	default y
1194	bool "Use a virtually-mapped stack"
1195	depends on HAVE_ARCH_VMAP_STACK
1196	depends on !KASAN || KASAN_HW_TAGS || KASAN_VMALLOC
1197	help
1198	  Enable this if you want the use virtually-mapped kernel stacks
1199	  with guard pages.  This causes kernel stack overflows to be
1200	  caught immediately rather than causing difficult-to-diagnose
1201	  corruption.
1202
1203	  To use this with software KASAN modes, the architecture must support
1204	  backing virtual mappings with real shadow memory, and KASAN_VMALLOC
1205	  must be enabled.
1206
1207config HAVE_ARCH_RANDOMIZE_KSTACK_OFFSET
1208	def_bool n
1209	help
1210	  An arch should select this symbol if it can support kernel stack
1211	  offset randomization with calls to add_random_kstack_offset()
1212	  during syscall entry and choose_random_kstack_offset() during
1213	  syscall exit. Careful removal of -fstack-protector-strong and
1214	  -fstack-protector should also be applied to the entry code and
1215	  closely examined, as the artificial stack bump looks like an array
1216	  to the compiler, so it will attempt to add canary checks regardless
1217	  of the static branch state.
1218
1219config RANDOMIZE_KSTACK_OFFSET
1220	bool "Support for randomizing kernel stack offset on syscall entry" if EXPERT
1221	default y
1222	depends on HAVE_ARCH_RANDOMIZE_KSTACK_OFFSET
1223	depends on INIT_STACK_NONE || !CC_IS_CLANG || CLANG_VERSION >= 140000
1224	help
1225	  The kernel stack offset can be randomized (after pt_regs) by
1226	  roughly 5 bits of entropy, frustrating memory corruption
1227	  attacks that depend on stack address determinism or
1228	  cross-syscall address exposures.
1229
1230	  The feature is controlled via the "randomize_kstack_offset=on/off"
1231	  kernel boot param, and if turned off has zero overhead due to its use
1232	  of static branches (see JUMP_LABEL).
1233
1234	  If unsure, say Y.
1235
1236config RANDOMIZE_KSTACK_OFFSET_DEFAULT
1237	bool "Default state of kernel stack offset randomization"
1238	depends on RANDOMIZE_KSTACK_OFFSET
1239	help
1240	  Kernel stack offset randomization is controlled by kernel boot param
1241	  "randomize_kstack_offset=on/off", and this config chooses the default
1242	  boot state.
1243
1244config ARCH_OPTIONAL_KERNEL_RWX
1245	def_bool n
1246
1247config ARCH_OPTIONAL_KERNEL_RWX_DEFAULT
1248	def_bool n
1249
1250config ARCH_HAS_STRICT_KERNEL_RWX
1251	def_bool n
1252
1253config STRICT_KERNEL_RWX
1254	bool "Make kernel text and rodata read-only" if ARCH_OPTIONAL_KERNEL_RWX
1255	depends on ARCH_HAS_STRICT_KERNEL_RWX
1256	default !ARCH_OPTIONAL_KERNEL_RWX || ARCH_OPTIONAL_KERNEL_RWX_DEFAULT
1257	help
1258	  If this is set, kernel text and rodata memory will be made read-only,
1259	  and non-text memory will be made non-executable. This provides
1260	  protection against certain security exploits (e.g. executing the heap
1261	  or modifying text)
1262
1263	  These features are considered standard security practice these days.
1264	  You should say Y here in almost all cases.
1265
1266config ARCH_HAS_STRICT_MODULE_RWX
1267	def_bool n
1268
1269config STRICT_MODULE_RWX
1270	bool "Set loadable kernel module data as NX and text as RO" if ARCH_OPTIONAL_KERNEL_RWX
1271	depends on ARCH_HAS_STRICT_MODULE_RWX && MODULES
1272	default !ARCH_OPTIONAL_KERNEL_RWX || ARCH_OPTIONAL_KERNEL_RWX_DEFAULT
1273	help
1274	  If this is set, module text and rodata memory will be made read-only,
1275	  and non-text memory will be made non-executable. This provides
1276	  protection against certain security exploits (e.g. writing to text)
1277
1278# select if the architecture provides an asm/dma-direct.h header
1279config ARCH_HAS_PHYS_TO_DMA
1280	bool
1281
1282config HAVE_ARCH_COMPILER_H
1283	bool
1284	help
1285	  An architecture can select this if it provides an
1286	  asm/compiler.h header that should be included after
1287	  linux/compiler-*.h in order to override macro definitions that those
1288	  headers generally provide.
1289
1290config HAVE_ARCH_PREL32_RELOCATIONS
1291	bool
1292	help
1293	  May be selected by an architecture if it supports place-relative
1294	  32-bit relocations, both in the toolchain and in the module loader,
1295	  in which case relative references can be used in special sections
1296	  for PCI fixup, initcalls etc which are only half the size on 64 bit
1297	  architectures, and don't require runtime relocation on relocatable
1298	  kernels.
1299
1300config ARCH_USE_MEMREMAP_PROT
1301	bool
1302
1303config LOCK_EVENT_COUNTS
1304	bool "Locking event counts collection"
1305	depends on DEBUG_FS
1306	help
1307	  Enable light-weight counting of various locking related events
1308	  in the system with minimal performance impact. This reduces
1309	  the chance of application behavior change because of timing
1310	  differences. The counts are reported via debugfs.
1311
1312# Select if the architecture has support for applying RELR relocations.
1313config ARCH_HAS_RELR
1314	bool
1315
1316config RELR
1317	bool "Use RELR relocation packing"
1318	depends on ARCH_HAS_RELR && TOOLS_SUPPORT_RELR
1319	default y
1320	help
1321	  Store the kernel's dynamic relocations in the RELR relocation packing
1322	  format. Requires a compatible linker (LLD supports this feature), as
1323	  well as compatible NM and OBJCOPY utilities (llvm-nm and llvm-objcopy
1324	  are compatible).
1325
1326config ARCH_HAS_MEM_ENCRYPT
1327	bool
1328
1329config ARCH_HAS_CC_PLATFORM
1330	bool
1331
1332config HAVE_SPARSE_SYSCALL_NR
1333	bool
1334	help
1335	  An architecture should select this if its syscall numbering is sparse
1336	  to save space. For example, MIPS architecture has a syscall array with
1337	  entries at 4000, 5000 and 6000 locations. This option turns on syscall
1338	  related optimizations for a given architecture.
1339
1340config ARCH_HAS_VDSO_DATA
1341	bool
1342
1343config HAVE_STATIC_CALL
1344	bool
1345
1346config HAVE_STATIC_CALL_INLINE
1347	bool
1348	depends on HAVE_STATIC_CALL
1349	select OBJTOOL
1350
1351config HAVE_PREEMPT_DYNAMIC
1352	bool
1353
1354config HAVE_PREEMPT_DYNAMIC_CALL
1355	bool
1356	depends on HAVE_STATIC_CALL
1357	select HAVE_PREEMPT_DYNAMIC
1358	help
1359	  An architecture should select this if it can handle the preemption
1360	  model being selected at boot time using static calls.
1361
1362	  Where an architecture selects HAVE_STATIC_CALL_INLINE, any call to a
1363	  preemption function will be patched directly.
1364
1365	  Where an architecture does not select HAVE_STATIC_CALL_INLINE, any
1366	  call to a preemption function will go through a trampoline, and the
1367	  trampoline will be patched.
1368
1369	  It is strongly advised to support inline static call to avoid any
1370	  overhead.
1371
1372config HAVE_PREEMPT_DYNAMIC_KEY
1373	bool
1374	depends on HAVE_ARCH_JUMP_LABEL
1375	select HAVE_PREEMPT_DYNAMIC
1376	help
1377	  An architecture should select this if it can handle the preemption
1378	  model being selected at boot time using static keys.
1379
1380	  Each preemption function will be given an early return based on a
1381	  static key. This should have slightly lower overhead than non-inline
1382	  static calls, as this effectively inlines each trampoline into the
1383	  start of its callee. This may avoid redundant work, and may
1384	  integrate better with CFI schemes.
1385
1386	  This will have greater overhead than using inline static calls as
1387	  the call to the preemption function cannot be entirely elided.
1388
1389config ARCH_WANT_LD_ORPHAN_WARN
1390	bool
1391	help
1392	  An arch should select this symbol once all linker sections are explicitly
1393	  included, size-asserted, or discarded in the linker scripts. This is
1394	  important because we never want expected sections to be placed heuristically
1395	  by the linker, since the locations of such sections can change between linker
1396	  versions.
1397
1398config HAVE_ARCH_PFN_VALID
1399	bool
1400
1401config ARCH_SUPPORTS_DEBUG_PAGEALLOC
1402	bool
1403
1404config ARCH_SUPPORTS_PAGE_TABLE_CHECK
1405	bool
1406
1407config ARCH_SPLIT_ARG64
1408	bool
1409	help
1410	  If a 32-bit architecture requires 64-bit arguments to be split into
1411	  pairs of 32-bit arguments, select this option.
1412
1413config ARCH_HAS_ELFCORE_COMPAT
1414	bool
1415
1416config ARCH_HAS_PARANOID_L1D_FLUSH
1417	bool
1418
1419config ARCH_HAVE_TRACE_MMIO_ACCESS
1420	bool
1421
1422config DYNAMIC_SIGFRAME
1423	bool
1424
1425# Select, if arch has a named attribute group bound to NUMA device nodes.
1426config HAVE_ARCH_NODE_DEV_GROUP
1427	bool
1428
1429config ARCH_HAS_NONLEAF_PMD_YOUNG
1430	bool
1431	help
1432	  Architectures that select this option are capable of setting the
1433	  accessed bit in non-leaf PMD entries when using them as part of linear
1434	  address translations. Page table walkers that clear the accessed bit
1435	  may use this capability to reduce their search space.
1436
1437source "kernel/gcov/Kconfig"
1438
1439source "scripts/gcc-plugins/Kconfig"
1440
1441config FUNCTION_ALIGNMENT_4B
1442	bool
1443
1444config FUNCTION_ALIGNMENT_8B
1445	bool
1446
1447config FUNCTION_ALIGNMENT_16B
1448	bool
1449
1450config FUNCTION_ALIGNMENT_32B
1451	bool
1452
1453config FUNCTION_ALIGNMENT_64B
1454	bool
1455
1456config FUNCTION_ALIGNMENT
1457	int
1458	default 64 if FUNCTION_ALIGNMENT_64B
1459	default 32 if FUNCTION_ALIGNMENT_32B
1460	default 16 if FUNCTION_ALIGNMENT_16B
1461	default 8 if FUNCTION_ALIGNMENT_8B
1462	default 4 if FUNCTION_ALIGNMENT_4B
1463	default 0
1464
1465endmenu
1466