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 ARCH_HAS_SUBPAGE_FAULTS
15	bool
16	help
17	  Select if the architecture can check permissions at sub-page
18	  granularity (e.g. arm64 MTE). The probe_user_*() functions
19	  must be implemented.
20
21config HOTPLUG_SMT
22	bool
23
24config SMT_NUM_THREADS_DYNAMIC
25	bool
26
27# Selected by HOTPLUG_CORE_SYNC_DEAD or HOTPLUG_CORE_SYNC_FULL
28config HOTPLUG_CORE_SYNC
29	bool
30
31# Basic CPU dead synchronization selected by architecture
32config HOTPLUG_CORE_SYNC_DEAD
33	bool
34	select HOTPLUG_CORE_SYNC
35
36# Full CPU synchronization with alive state selected by architecture
37config HOTPLUG_CORE_SYNC_FULL
38	bool
39	select HOTPLUG_CORE_SYNC_DEAD if HOTPLUG_CPU
40	select HOTPLUG_CORE_SYNC
41
42config HOTPLUG_SPLIT_STARTUP
43	bool
44	select HOTPLUG_CORE_SYNC_FULL
45
46config HOTPLUG_PARALLEL
47	bool
48	select HOTPLUG_SPLIT_STARTUP
49
50config GENERIC_ENTRY
51	bool
52
53config KPROBES
54	bool "Kprobes"
55	depends on MODULES
56	depends on HAVE_KPROBES
57	select KALLSYMS
58	select TASKS_RCU if PREEMPTION
59	help
60	  Kprobes allows you to trap at almost any kernel address and
61	  execute a callback function.  register_kprobe() establishes
62	  a probepoint and specifies the callback.  Kprobes is useful
63	  for kernel debugging, non-intrusive instrumentation and testing.
64	  If in doubt, say "N".
65
66config JUMP_LABEL
67	bool "Optimize very unlikely/likely branches"
68	depends on HAVE_ARCH_JUMP_LABEL
69	select OBJTOOL if HAVE_JUMP_LABEL_HACK
70	help
71	  This option enables a transparent branch optimization that
72	  makes certain almost-always-true or almost-always-false branch
73	  conditions even cheaper to execute within the kernel.
74
75	  Certain performance-sensitive kernel code, such as trace points,
76	  scheduler functionality, networking code and KVM have such
77	  branches and include support for this optimization technique.
78
79	  If it is detected that the compiler has support for "asm goto",
80	  the kernel will compile such branches with just a nop
81	  instruction. When the condition flag is toggled to true, the
82	  nop will be converted to a jump instruction to execute the
83	  conditional block of instructions.
84
85	  This technique lowers overhead and stress on the branch prediction
86	  of the processor and generally makes the kernel faster. The update
87	  of the condition is slower, but those are always very rare.
88
89	  ( On 32-bit x86, the necessary options added to the compiler
90	    flags may increase the size of the kernel slightly. )
91
92config STATIC_KEYS_SELFTEST
93	bool "Static key selftest"
94	depends on JUMP_LABEL
95	help
96	  Boot time self-test of the branch patching code.
97
98config STATIC_CALL_SELFTEST
99	bool "Static call selftest"
100	depends on HAVE_STATIC_CALL
101	help
102	  Boot time self-test of the call patching code.
103
104config OPTPROBES
105	def_bool y
106	depends on KPROBES && HAVE_OPTPROBES
107	select TASKS_RCU if PREEMPTION
108
109config KPROBES_ON_FTRACE
110	def_bool y
111	depends on KPROBES && HAVE_KPROBES_ON_FTRACE
112	depends on DYNAMIC_FTRACE_WITH_REGS
113	help
114	  If function tracer is enabled and the arch supports full
115	  passing of pt_regs to function tracing, then kprobes can
116	  optimize on top of function tracing.
117
118config UPROBES
119	def_bool n
120	depends on ARCH_SUPPORTS_UPROBES
121	help
122	  Uprobes is the user-space counterpart to kprobes: they
123	  enable instrumentation applications (such as 'perf probe')
124	  to establish unintrusive probes in user-space binaries and
125	  libraries, by executing handler functions when the probes
126	  are hit by user-space applications.
127
128	  ( These probes come in the form of single-byte breakpoints,
129	    managed by the kernel and kept transparent to the probed
130	    application. )
131
132config HAVE_64BIT_ALIGNED_ACCESS
133	def_bool 64BIT && !HAVE_EFFICIENT_UNALIGNED_ACCESS
134	help
135	  Some architectures require 64 bit accesses to be 64 bit
136	  aligned, which also requires structs containing 64 bit values
137	  to be 64 bit aligned too. This includes some 32 bit
138	  architectures which can do 64 bit accesses, as well as 64 bit
139	  architectures without unaligned access.
140
141	  This symbol should be selected by an architecture if 64 bit
142	  accesses are required to be 64 bit aligned in this way even
143	  though it is not a 64 bit architecture.
144
145	  See Documentation/core-api/unaligned-memory-access.rst for
146	  more information on the topic of unaligned memory accesses.
147
148config HAVE_EFFICIENT_UNALIGNED_ACCESS
149	bool
150	help
151	  Some architectures are unable to perform unaligned accesses
152	  without the use of get_unaligned/put_unaligned. Others are
153	  unable to perform such accesses efficiently (e.g. trap on
154	  unaligned access and require fixing it up in the exception
155	  handler.)
156
157	  This symbol should be selected by an architecture if it can
158	  perform unaligned accesses efficiently to allow different
159	  code paths to be selected for these cases. Some network
160	  drivers, for example, could opt to not fix up alignment
161	  problems with received packets if doing so would not help
162	  much.
163
164	  See Documentation/core-api/unaligned-memory-access.rst for more
165	  information on the topic of unaligned memory accesses.
166
167config ARCH_USE_BUILTIN_BSWAP
168	bool
169	help
170	  Modern versions of GCC (since 4.4) have builtin functions
171	  for handling byte-swapping. Using these, instead of the old
172	  inline assembler that the architecture code provides in the
173	  __arch_bswapXX() macros, allows the compiler to see what's
174	  happening and offers more opportunity for optimisation. In
175	  particular, the compiler will be able to combine the byteswap
176	  with a nearby load or store and use load-and-swap or
177	  store-and-swap instructions if the architecture has them. It
178	  should almost *never* result in code which is worse than the
179	  hand-coded assembler in <asm/swab.h>.  But just in case it
180	  does, the use of the builtins is optional.
181
182	  Any architecture with load-and-swap or store-and-swap
183	  instructions should set this. And it shouldn't hurt to set it
184	  on architectures that don't have such instructions.
185
186config KRETPROBES
187	def_bool y
188	depends on KPROBES && (HAVE_KRETPROBES || HAVE_RETHOOK)
189
190config KRETPROBE_ON_RETHOOK
191	def_bool y
192	depends on HAVE_RETHOOK
193	depends on KRETPROBES
194	select RETHOOK
195
196config USER_RETURN_NOTIFIER
197	bool
198	depends on HAVE_USER_RETURN_NOTIFIER
199	help
200	  Provide a kernel-internal notification when a cpu is about to
201	  switch to user mode.
202
203config HAVE_IOREMAP_PROT
204	bool
205
206config HAVE_KPROBES
207	bool
208
209config HAVE_KRETPROBES
210	bool
211
212config HAVE_OPTPROBES
213	bool
214
215config HAVE_KPROBES_ON_FTRACE
216	bool
217
218config ARCH_CORRECT_STACKTRACE_ON_KRETPROBE
219	bool
220	help
221	  Since kretprobes modifies return address on the stack, the
222	  stacktrace may see the kretprobe trampoline address instead
223	  of correct one. If the architecture stacktrace code and
224	  unwinder can adjust such entries, select this configuration.
225
226config HAVE_FUNCTION_ERROR_INJECTION
227	bool
228
229config HAVE_NMI
230	bool
231
232config HAVE_FUNCTION_DESCRIPTORS
233	bool
234
235config TRACE_IRQFLAGS_SUPPORT
236	bool
237
238config TRACE_IRQFLAGS_NMI_SUPPORT
239	bool
240
241#
242# An arch should select this if it provides all these things:
243#
244#	task_pt_regs()		in asm/processor.h or asm/ptrace.h
245#	arch_has_single_step()	if there is hardware single-step support
246#	arch_has_block_step()	if there is hardware block-step support
247#	asm/syscall.h		supplying asm-generic/syscall.h interface
248#	linux/regset.h		user_regset interfaces
249#	CORE_DUMP_USE_REGSET	#define'd in linux/elf.h
250#	TIF_SYSCALL_TRACE	calls ptrace_report_syscall_{entry,exit}
251#	TIF_NOTIFY_RESUME	calls resume_user_mode_work()
252#
253config HAVE_ARCH_TRACEHOOK
254	bool
255
256config HAVE_DMA_CONTIGUOUS
257	bool
258
259config GENERIC_SMP_IDLE_THREAD
260	bool
261
262config GENERIC_IDLE_POLL_SETUP
263	bool
264
265config ARCH_HAS_FORTIFY_SOURCE
266	bool
267	help
268	  An architecture should select this when it can successfully
269	  build and run with CONFIG_FORTIFY_SOURCE.
270
271#
272# Select if the arch provides a historic keepinit alias for the retain_initrd
273# command line option
274#
275config ARCH_HAS_KEEPINITRD
276	bool
277
278# Select if arch has all set_memory_ro/rw/x/nx() functions in asm/cacheflush.h
279config ARCH_HAS_SET_MEMORY
280	bool
281
282# Select if arch has all set_direct_map_invalid/default() functions
283config ARCH_HAS_SET_DIRECT_MAP
284	bool
285
286#
287# Select if the architecture provides the arch_dma_set_uncached symbol to
288# either provide an uncached segment alias for a DMA allocation, or
289# to remap the page tables in place.
290#
291config ARCH_HAS_DMA_SET_UNCACHED
292	bool
293
294#
295# Select if the architectures provides the arch_dma_clear_uncached symbol
296# to undo an in-place page table remap for uncached access.
297#
298config ARCH_HAS_DMA_CLEAR_UNCACHED
299	bool
300
301config ARCH_HAS_CPU_FINALIZE_INIT
302	bool
303
304# Select if arch init_task must go in the __init_task_data section
305config ARCH_TASK_STRUCT_ON_STACK
306	bool
307
308# Select if arch has its private alloc_task_struct() function
309config ARCH_TASK_STRUCT_ALLOCATOR
310	bool
311
312config HAVE_ARCH_THREAD_STRUCT_WHITELIST
313	bool
314	depends on !ARCH_TASK_STRUCT_ALLOCATOR
315	help
316	  An architecture should select this to provide hardened usercopy
317	  knowledge about what region of the thread_struct should be
318	  whitelisted for copying to userspace. Normally this is only the
319	  FPU registers. Specifically, arch_thread_struct_whitelist()
320	  should be implemented. Without this, the entire thread_struct
321	  field in task_struct will be left whitelisted.
322
323# Select if arch has its private alloc_thread_stack() function
324config ARCH_THREAD_STACK_ALLOCATOR
325	bool
326
327# Select if arch wants to size task_struct dynamically via arch_task_struct_size:
328config ARCH_WANTS_DYNAMIC_TASK_STRUCT
329	bool
330
331config ARCH_WANTS_NO_INSTR
332	bool
333	help
334	  An architecture should select this if the noinstr macro is being used on
335	  functions to denote that the toolchain should avoid instrumenting such
336	  functions and is required for correctness.
337
338config ARCH_32BIT_OFF_T
339	bool
340	depends on !64BIT
341	help
342	  All new 32-bit architectures should have 64-bit off_t type on
343	  userspace side which corresponds to the loff_t kernel type. This
344	  is the requirement for modern ABIs. Some existing architectures
345	  still support 32-bit off_t. This option is enabled for all such
346	  architectures explicitly.
347
348# Selected by 64 bit architectures which have a 32 bit f_tinode in struct ustat
349config ARCH_32BIT_USTAT_F_TINODE
350	bool
351
352config HAVE_ASM_MODVERSIONS
353	bool
354	help
355	  This symbol should be selected by an architecture if it provides
356	  <asm/asm-prototypes.h> to support the module versioning for symbols
357	  exported from assembly code.
358
359config HAVE_REGS_AND_STACK_ACCESS_API
360	bool
361	help
362	  This symbol should be selected by an architecture if it supports
363	  the API needed to access registers and stack entries from pt_regs,
364	  declared in asm/ptrace.h
365	  For example the kprobes-based event tracer needs this API.
366
367config HAVE_RSEQ
368	bool
369	depends on HAVE_REGS_AND_STACK_ACCESS_API
370	help
371	  This symbol should be selected by an architecture if it
372	  supports an implementation of restartable sequences.
373
374config HAVE_RUST
375	bool
376	help
377	  This symbol should be selected by an architecture if it
378	  supports Rust.
379
380config HAVE_FUNCTION_ARG_ACCESS_API
381	bool
382	help
383	  This symbol should be selected by an architecture if it supports
384	  the API needed to access function arguments from pt_regs,
385	  declared in asm/ptrace.h
386
387config HAVE_HW_BREAKPOINT
388	bool
389	depends on PERF_EVENTS
390
391config HAVE_MIXED_BREAKPOINTS_REGS
392	bool
393	depends on HAVE_HW_BREAKPOINT
394	help
395	  Depending on the arch implementation of hardware breakpoints,
396	  some of them have separate registers for data and instruction
397	  breakpoints addresses, others have mixed registers to store
398	  them but define the access type in a control register.
399	  Select this option if your arch implements breakpoints under the
400	  latter fashion.
401
402config HAVE_USER_RETURN_NOTIFIER
403	bool
404
405config HAVE_PERF_EVENTS_NMI
406	bool
407	help
408	  System hardware can generate an NMI using the perf event
409	  subsystem.  Also has support for calculating CPU cycle events
410	  to determine how many clock cycles in a given period.
411
412config HAVE_HARDLOCKUP_DETECTOR_PERF
413	bool
414	depends on HAVE_PERF_EVENTS_NMI
415	help
416	  The arch chooses to use the generic perf-NMI-based hardlockup
417	  detector. Must define HAVE_PERF_EVENTS_NMI.
418
419config HAVE_HARDLOCKUP_DETECTOR_ARCH
420	bool
421	help
422	  The arch provides its own hardlockup detector implementation instead
423	  of the generic ones.
424
425	  It uses the same command line parameters, and sysctl interface,
426	  as the generic hardlockup detectors.
427
428config HAVE_PERF_REGS
429	bool
430	help
431	  Support selective register dumps for perf events. This includes
432	  bit-mapping of each registers and a unique architecture id.
433
434config HAVE_PERF_USER_STACK_DUMP
435	bool
436	help
437	  Support user stack dumps for perf event samples. This needs
438	  access to the user stack pointer which is not unified across
439	  architectures.
440
441config HAVE_ARCH_JUMP_LABEL
442	bool
443
444config HAVE_ARCH_JUMP_LABEL_RELATIVE
445	bool
446
447config MMU_GATHER_TABLE_FREE
448	bool
449
450config MMU_GATHER_RCU_TABLE_FREE
451	bool
452	select MMU_GATHER_TABLE_FREE
453
454config MMU_GATHER_PAGE_SIZE
455	bool
456
457config MMU_GATHER_NO_RANGE
458	bool
459	select MMU_GATHER_MERGE_VMAS
460
461config MMU_GATHER_NO_FLUSH_CACHE
462	bool
463
464config MMU_GATHER_MERGE_VMAS
465	bool
466
467config MMU_GATHER_NO_GATHER
468	bool
469	depends on MMU_GATHER_TABLE_FREE
470
471config ARCH_WANT_IRQS_OFF_ACTIVATE_MM
472	bool
473	help
474	  Temporary select until all architectures can be converted to have
475	  irqs disabled over activate_mm. Architectures that do IPI based TLB
476	  shootdowns should enable this.
477
478# Use normal mm refcounting for MMU_LAZY_TLB kernel thread references.
479# MMU_LAZY_TLB_REFCOUNT=n can improve the scalability of context switching
480# to/from kernel threads when the same mm is running on a lot of CPUs (a large
481# multi-threaded application), by reducing contention on the mm refcount.
482#
483# This can be disabled if the architecture ensures no CPUs are using an mm as a
484# "lazy tlb" beyond its final refcount (i.e., by the time __mmdrop frees the mm
485# or its kernel page tables). This could be arranged by arch_exit_mmap(), or
486# final exit(2) TLB flush, for example.
487#
488# To implement this, an arch *must*:
489# Ensure the _lazy_tlb variants of mmgrab/mmdrop are used when manipulating
490# the lazy tlb reference of a kthread's ->active_mm (non-arch code has been
491# converted already).
492config MMU_LAZY_TLB_REFCOUNT
493	def_bool y
494	depends on !MMU_LAZY_TLB_SHOOTDOWN
495
496# This option allows MMU_LAZY_TLB_REFCOUNT=n. It ensures no CPUs are using an
497# mm as a lazy tlb beyond its last reference count, by shooting down these
498# users before the mm is deallocated. __mmdrop() first IPIs all CPUs that may
499# be using the mm as a lazy tlb, so that they may switch themselves to using
500# init_mm for their active mm. mm_cpumask(mm) is used to determine which CPUs
501# may be using mm as a lazy tlb mm.
502#
503# To implement this, an arch *must*:
504# - At the time of the final mmdrop of the mm, ensure mm_cpumask(mm) contains
505#   at least all possible CPUs in which the mm is lazy.
506# - It must meet the requirements for MMU_LAZY_TLB_REFCOUNT=n (see above).
507config MMU_LAZY_TLB_SHOOTDOWN
508	bool
509
510config ARCH_HAVE_NMI_SAFE_CMPXCHG
511	bool
512
513config ARCH_HAS_NMI_SAFE_THIS_CPU_OPS
514	bool
515
516config HAVE_ALIGNED_STRUCT_PAGE
517	bool
518	help
519	  This makes sure that struct pages are double word aligned and that
520	  e.g. the SLUB allocator can perform double word atomic operations
521	  on a struct page for better performance. However selecting this
522	  might increase the size of a struct page by a word.
523
524config HAVE_CMPXCHG_LOCAL
525	bool
526
527config HAVE_CMPXCHG_DOUBLE
528	bool
529
530config ARCH_WEAK_RELEASE_ACQUIRE
531	bool
532
533config ARCH_WANT_IPC_PARSE_VERSION
534	bool
535
536config ARCH_WANT_COMPAT_IPC_PARSE_VERSION
537	bool
538
539config ARCH_WANT_OLD_COMPAT_IPC
540	select ARCH_WANT_COMPAT_IPC_PARSE_VERSION
541	bool
542
543config HAVE_ARCH_SECCOMP
544	bool
545	help
546	  An arch should select this symbol to support seccomp mode 1 (the fixed
547	  syscall policy), and must provide an overrides for __NR_seccomp_sigreturn,
548	  and compat syscalls if the asm-generic/seccomp.h defaults need adjustment:
549	  - __NR_seccomp_read_32
550	  - __NR_seccomp_write_32
551	  - __NR_seccomp_exit_32
552	  - __NR_seccomp_sigreturn_32
553
554config HAVE_ARCH_SECCOMP_FILTER
555	bool
556	select HAVE_ARCH_SECCOMP
557	help
558	  An arch should select this symbol if it provides all of these things:
559	  - all the requirements for HAVE_ARCH_SECCOMP
560	  - syscall_get_arch()
561	  - syscall_get_arguments()
562	  - syscall_rollback()
563	  - syscall_set_return_value()
564	  - SIGSYS siginfo_t support
565	  - secure_computing is called from a ptrace_event()-safe context
566	  - secure_computing return value is checked and a return value of -1
567	    results in the system call being skipped immediately.
568	  - seccomp syscall wired up
569	  - if !HAVE_SPARSE_SYSCALL_NR, have SECCOMP_ARCH_NATIVE,
570	    SECCOMP_ARCH_NATIVE_NR, SECCOMP_ARCH_NATIVE_NAME defined. If
571	    COMPAT is supported, have the SECCOMP_ARCH_COMPAT* defines too.
572
573config SECCOMP
574	prompt "Enable seccomp to safely execute untrusted bytecode"
575	def_bool y
576	depends on HAVE_ARCH_SECCOMP
577	help
578	  This kernel feature is useful for number crunching applications
579	  that may need to handle untrusted bytecode during their
580	  execution. By using pipes or other transports made available
581	  to the process as file descriptors supporting the read/write
582	  syscalls, it's possible to isolate those applications in their
583	  own address space using seccomp. Once seccomp is enabled via
584	  prctl(PR_SET_SECCOMP) or the seccomp() syscall, it cannot be
585	  disabled and the task is only allowed to execute a few safe
586	  syscalls defined by each seccomp mode.
587
588	  If unsure, say Y.
589
590config SECCOMP_FILTER
591	def_bool y
592	depends on HAVE_ARCH_SECCOMP_FILTER && SECCOMP && NET
593	help
594	  Enable tasks to build secure computing environments defined
595	  in terms of Berkeley Packet Filter programs which implement
596	  task-defined system call filtering polices.
597
598	  See Documentation/userspace-api/seccomp_filter.rst for details.
599
600config SECCOMP_CACHE_DEBUG
601	bool "Show seccomp filter cache status in /proc/pid/seccomp_cache"
602	depends on SECCOMP_FILTER && !HAVE_SPARSE_SYSCALL_NR
603	depends on PROC_FS
604	help
605	  This enables the /proc/pid/seccomp_cache interface to monitor
606	  seccomp cache data. The file format is subject to change. Reading
607	  the file requires CAP_SYS_ADMIN.
608
609	  This option is for debugging only. Enabling presents the risk that
610	  an adversary may be able to infer the seccomp filter logic.
611
612	  If unsure, say N.
613
614config HAVE_ARCH_STACKLEAK
615	bool
616	help
617	  An architecture should select this if it has the code which
618	  fills the used part of the kernel stack with the STACKLEAK_POISON
619	  value before returning from system calls.
620
621config HAVE_STACKPROTECTOR
622	bool
623	help
624	  An arch should select this symbol if:
625	  - it has implemented a stack canary (e.g. __stack_chk_guard)
626
627config STACKPROTECTOR
628	bool "Stack Protector buffer overflow detection"
629	depends on HAVE_STACKPROTECTOR
630	depends on $(cc-option,-fstack-protector)
631	default y
632	help
633	  This option turns on the "stack-protector" GCC feature. This
634	  feature puts, at the beginning of functions, a canary value on
635	  the stack just before the return address, and validates
636	  the value just before actually returning.  Stack based buffer
637	  overflows (that need to overwrite this return address) now also
638	  overwrite the canary, which gets detected and the attack is then
639	  neutralized via a kernel panic.
640
641	  Functions will have the stack-protector canary logic added if they
642	  have an 8-byte or larger character array on the stack.
643
644	  This feature requires gcc version 4.2 or above, or a distribution
645	  gcc with the feature backported ("-fstack-protector").
646
647	  On an x86 "defconfig" build, this feature adds canary checks to
648	  about 3% of all kernel functions, which increases kernel code size
649	  by about 0.3%.
650
651config STACKPROTECTOR_STRONG
652	bool "Strong Stack Protector"
653	depends on STACKPROTECTOR
654	depends on $(cc-option,-fstack-protector-strong)
655	default y
656	help
657	  Functions will have the stack-protector canary logic added in any
658	  of the following conditions:
659
660	  - local variable's address used as part of the right hand side of an
661	    assignment or function argument
662	  - local variable is an array (or union containing an array),
663	    regardless of array type or length
664	  - uses register local variables
665
666	  This feature requires gcc version 4.9 or above, or a distribution
667	  gcc with the feature backported ("-fstack-protector-strong").
668
669	  On an x86 "defconfig" build, this feature adds canary checks to
670	  about 20% of all kernel functions, which increases the kernel code
671	  size by about 2%.
672
673config ARCH_SUPPORTS_SHADOW_CALL_STACK
674	bool
675	help
676	  An architecture should select this if it supports the compiler's
677	  Shadow Call Stack and implements runtime support for shadow stack
678	  switching.
679
680config SHADOW_CALL_STACK
681	bool "Shadow Call Stack"
682	depends on ARCH_SUPPORTS_SHADOW_CALL_STACK
683	depends on DYNAMIC_FTRACE_WITH_ARGS || DYNAMIC_FTRACE_WITH_REGS || !FUNCTION_GRAPH_TRACER
684	depends on MMU
685	help
686	  This option enables the compiler's Shadow Call Stack, which
687	  uses a shadow stack to protect function return addresses from
688	  being overwritten by an attacker. More information can be found
689	  in the compiler's documentation:
690
691	  - Clang: https://clang.llvm.org/docs/ShadowCallStack.html
692	  - GCC: https://gcc.gnu.org/onlinedocs/gcc/Instrumentation-Options.html#Instrumentation-Options
693
694	  Note that security guarantees in the kernel differ from the
695	  ones documented for user space. The kernel must store addresses
696	  of shadow stacks in memory, which means an attacker capable of
697	  reading and writing arbitrary memory may be able to locate them
698	  and hijack control flow by modifying the stacks.
699
700config DYNAMIC_SCS
701	bool
702	help
703	  Set by the arch code if it relies on code patching to insert the
704	  shadow call stack push and pop instructions rather than on the
705	  compiler.
706
707config LTO
708	bool
709	help
710	  Selected if the kernel will be built using the compiler's LTO feature.
711
712config LTO_CLANG
713	bool
714	select LTO
715	help
716	  Selected if the kernel will be built using Clang's LTO feature.
717
718config ARCH_SUPPORTS_LTO_CLANG
719	bool
720	help
721	  An architecture should select this option if it supports:
722	  - compiling with Clang,
723	  - compiling inline assembly with Clang's integrated assembler,
724	  - and linking with LLD.
725
726config ARCH_SUPPORTS_LTO_CLANG_THIN
727	bool
728	help
729	  An architecture should select this option if it can support Clang's
730	  ThinLTO mode.
731
732config HAS_LTO_CLANG
733	def_bool y
734	depends on CC_IS_CLANG && LD_IS_LLD && AS_IS_LLVM
735	depends on $(success,$(NM) --help | head -n 1 | grep -qi llvm)
736	depends on $(success,$(AR) --help | head -n 1 | grep -qi llvm)
737	depends on ARCH_SUPPORTS_LTO_CLANG
738	depends on !FTRACE_MCOUNT_USE_RECORDMCOUNT
739	# https://github.com/ClangBuiltLinux/linux/issues/1721
740	depends on (!KASAN || KASAN_HW_TAGS || CLANG_VERSION >= 170000) || !DEBUG_INFO
741	depends on (!KCOV || CLANG_VERSION >= 170000) || !DEBUG_INFO
742	depends on !GCOV_KERNEL
743	help
744	  The compiler and Kconfig options support building with Clang's
745	  LTO.
746
747choice
748	prompt "Link Time Optimization (LTO)"
749	default LTO_NONE
750	help
751	  This option enables Link Time Optimization (LTO), which allows the
752	  compiler to optimize binaries globally.
753
754	  If unsure, select LTO_NONE. Note that LTO is very resource-intensive
755	  so it's disabled by default.
756
757config LTO_NONE
758	bool "None"
759	help
760	  Build the kernel normally, without Link Time Optimization (LTO).
761
762config LTO_CLANG_FULL
763	bool "Clang Full LTO (EXPERIMENTAL)"
764	depends on HAS_LTO_CLANG
765	depends on !COMPILE_TEST
766	select LTO_CLANG
767	help
768	  This option enables Clang's full Link Time Optimization (LTO), which
769	  allows the compiler to optimize the kernel globally. If you enable
770	  this option, the compiler generates LLVM bitcode instead of ELF
771	  object files, and the actual compilation from bitcode happens at
772	  the LTO link step, which may take several minutes depending on the
773	  kernel configuration. More information can be found from LLVM's
774	  documentation:
775
776	    https://llvm.org/docs/LinkTimeOptimization.html
777
778	  During link time, this option can use a large amount of RAM, and
779	  may take much longer than the ThinLTO option.
780
781config LTO_CLANG_THIN
782	bool "Clang ThinLTO (EXPERIMENTAL)"
783	depends on HAS_LTO_CLANG && ARCH_SUPPORTS_LTO_CLANG_THIN
784	select LTO_CLANG
785	help
786	  This option enables Clang's ThinLTO, which allows for parallel
787	  optimization and faster incremental compiles compared to the
788	  CONFIG_LTO_CLANG_FULL option. More information can be found
789	  from Clang's documentation:
790
791	    https://clang.llvm.org/docs/ThinLTO.html
792
793	  If unsure, say Y.
794endchoice
795
796config ARCH_SUPPORTS_CFI_CLANG
797	bool
798	help
799	  An architecture should select this option if it can support Clang's
800	  Control-Flow Integrity (CFI) checking.
801
802config ARCH_USES_CFI_TRAPS
803	bool
804
805config CFI_CLANG
806	bool "Use Clang's Control Flow Integrity (CFI)"
807	depends on ARCH_SUPPORTS_CFI_CLANG
808	depends on $(cc-option,-fsanitize=kcfi)
809	help
810	  This option enables Clang’s forward-edge Control Flow Integrity
811	  (CFI) checking, where the compiler injects a runtime check to each
812	  indirect function call to ensure the target is a valid function with
813	  the correct static type. This restricts possible call targets and
814	  makes it more difficult for an attacker to exploit bugs that allow
815	  the modification of stored function pointers. More information can be
816	  found from Clang's documentation:
817
818	    https://clang.llvm.org/docs/ControlFlowIntegrity.html
819
820config CFI_PERMISSIVE
821	bool "Use CFI in permissive mode"
822	depends on CFI_CLANG
823	help
824	  When selected, Control Flow Integrity (CFI) violations result in a
825	  warning instead of a kernel panic. This option should only be used
826	  for finding indirect call type mismatches during development.
827
828	  If unsure, say N.
829
830config HAVE_ARCH_WITHIN_STACK_FRAMES
831	bool
832	help
833	  An architecture should select this if it can walk the kernel stack
834	  frames to determine if an object is part of either the arguments
835	  or local variables (i.e. that it excludes saved return addresses,
836	  and similar) by implementing an inline arch_within_stack_frames(),
837	  which is used by CONFIG_HARDENED_USERCOPY.
838
839config HAVE_CONTEXT_TRACKING_USER
840	bool
841	help
842	  Provide kernel/user boundaries probes necessary for subsystems
843	  that need it, such as userspace RCU extended quiescent state.
844	  Syscalls need to be wrapped inside user_exit()-user_enter(), either
845	  optimized behind static key or through the slow path using TIF_NOHZ
846	  flag. Exceptions handlers must be wrapped as well. Irqs are already
847	  protected inside ct_irq_enter/ct_irq_exit() but preemption or signal
848	  handling on irq exit still need to be protected.
849
850config HAVE_CONTEXT_TRACKING_USER_OFFSTACK
851	bool
852	help
853	  Architecture neither relies on exception_enter()/exception_exit()
854	  nor on schedule_user(). Also preempt_schedule_notrace() and
855	  preempt_schedule_irq() can't be called in a preemptible section
856	  while context tracking is CONTEXT_USER. This feature reflects a sane
857	  entry implementation where the following requirements are met on
858	  critical entry code, ie: before user_exit() or after user_enter():
859
860	  - Critical entry code isn't preemptible (or better yet:
861	    not interruptible).
862	  - No use of RCU read side critical sections, unless ct_nmi_enter()
863	    got called.
864	  - No use of instrumentation, unless instrumentation_begin() got
865	    called.
866
867config HAVE_TIF_NOHZ
868	bool
869	help
870	  Arch relies on TIF_NOHZ and syscall slow path to implement context
871	  tracking calls to user_enter()/user_exit().
872
873config HAVE_VIRT_CPU_ACCOUNTING
874	bool
875
876config HAVE_VIRT_CPU_ACCOUNTING_IDLE
877	bool
878	help
879	  Architecture has its own way to account idle CPU time and therefore
880	  doesn't implement vtime_account_idle().
881
882config ARCH_HAS_SCALED_CPUTIME
883	bool
884
885config HAVE_VIRT_CPU_ACCOUNTING_GEN
886	bool
887	default y if 64BIT
888	help
889	  With VIRT_CPU_ACCOUNTING_GEN, cputime_t becomes 64-bit.
890	  Before enabling this option, arch code must be audited
891	  to ensure there are no races in concurrent read/write of
892	  cputime_t. For example, reading/writing 64-bit cputime_t on
893	  some 32-bit arches may require multiple accesses, so proper
894	  locking is needed to protect against concurrent accesses.
895
896config HAVE_IRQ_TIME_ACCOUNTING
897	bool
898	help
899	  Archs need to ensure they use a high enough resolution clock to
900	  support irq time accounting and then call enable_sched_clock_irqtime().
901
902config HAVE_MOVE_PUD
903	bool
904	help
905	  Architectures that select this are able to move page tables at the
906	  PUD level. If there are only 3 page table levels, the move effectively
907	  happens at the PGD level.
908
909config HAVE_MOVE_PMD
910	bool
911	help
912	  Archs that select this are able to move page tables at the PMD level.
913
914config HAVE_ARCH_TRANSPARENT_HUGEPAGE
915	bool
916
917config HAVE_ARCH_TRANSPARENT_HUGEPAGE_PUD
918	bool
919
920config HAVE_ARCH_HUGE_VMAP
921	bool
922
923#
924#  Archs that select this would be capable of PMD-sized vmaps (i.e.,
925#  arch_vmap_pmd_supported() returns true). The VM_ALLOW_HUGE_VMAP flag
926#  must be used to enable allocations to use hugepages.
927#
928config HAVE_ARCH_HUGE_VMALLOC
929	depends on HAVE_ARCH_HUGE_VMAP
930	bool
931
932config ARCH_WANT_HUGE_PMD_SHARE
933	bool
934
935# Archs that want to use pmd_mkwrite on kernel memory need it defined even
936# if there are no userspace memory management features that use it
937config ARCH_WANT_KERNEL_PMD_MKWRITE
938	bool
939
940config ARCH_WANT_PMD_MKWRITE
941	def_bool TRANSPARENT_HUGEPAGE || ARCH_WANT_KERNEL_PMD_MKWRITE
942
943config HAVE_ARCH_SOFT_DIRTY
944	bool
945
946config HAVE_MOD_ARCH_SPECIFIC
947	bool
948	help
949	  The arch uses struct mod_arch_specific to store data.  Many arches
950	  just need a simple module loader without arch specific data - those
951	  should not enable this.
952
953config MODULES_USE_ELF_RELA
954	bool
955	help
956	  Modules only use ELF RELA relocations.  Modules with ELF REL
957	  relocations will give an error.
958
959config MODULES_USE_ELF_REL
960	bool
961	help
962	  Modules only use ELF REL relocations.  Modules with ELF RELA
963	  relocations will give an error.
964
965config ARCH_WANTS_MODULES_DATA_IN_VMALLOC
966	bool
967	help
968	  For architectures like powerpc/32 which have constraints on module
969	  allocation and need to allocate module data outside of module area.
970
971config HAVE_IRQ_EXIT_ON_IRQ_STACK
972	bool
973	help
974	  Architecture doesn't only execute the irq handler on the irq stack
975	  but also irq_exit(). This way we can process softirqs on this irq
976	  stack instead of switching to a new one when we call __do_softirq()
977	  in the end of an hardirq.
978	  This spares a stack switch and improves cache usage on softirq
979	  processing.
980
981config HAVE_SOFTIRQ_ON_OWN_STACK
982	bool
983	help
984	  Architecture provides a function to run __do_softirq() on a
985	  separate stack.
986
987config SOFTIRQ_ON_OWN_STACK
988	def_bool HAVE_SOFTIRQ_ON_OWN_STACK && !PREEMPT_RT
989
990config ALTERNATE_USER_ADDRESS_SPACE
991	bool
992	help
993	  Architectures set this when the CPU uses separate address
994	  spaces for kernel and user space pointers. In this case, the
995	  access_ok() check on a __user pointer is skipped.
996
997config PGTABLE_LEVELS
998	int
999	default 2
1000
1001config ARCH_HAS_ELF_RANDOMIZE
1002	bool
1003	help
1004	  An architecture supports choosing randomized locations for
1005	  stack, mmap, brk, and ET_DYN. Defined functions:
1006	  - arch_mmap_rnd()
1007	  - arch_randomize_brk()
1008
1009config HAVE_ARCH_MMAP_RND_BITS
1010	bool
1011	help
1012	  An arch should select this symbol if it supports setting a variable
1013	  number of bits for use in establishing the base address for mmap
1014	  allocations, has MMU enabled and provides values for both:
1015	  - ARCH_MMAP_RND_BITS_MIN
1016	  - ARCH_MMAP_RND_BITS_MAX
1017
1018config HAVE_EXIT_THREAD
1019	bool
1020	help
1021	  An architecture implements exit_thread.
1022
1023config ARCH_MMAP_RND_BITS_MIN
1024	int
1025
1026config ARCH_MMAP_RND_BITS_MAX
1027	int
1028
1029config ARCH_MMAP_RND_BITS_DEFAULT
1030	int
1031
1032config ARCH_MMAP_RND_BITS
1033	int "Number of bits to use for ASLR of mmap base address" if EXPERT
1034	range ARCH_MMAP_RND_BITS_MIN ARCH_MMAP_RND_BITS_MAX
1035	default ARCH_MMAP_RND_BITS_DEFAULT if ARCH_MMAP_RND_BITS_DEFAULT
1036	default ARCH_MMAP_RND_BITS_MIN
1037	depends on HAVE_ARCH_MMAP_RND_BITS
1038	help
1039	  This value can be used to select the number of bits to use to
1040	  determine the random offset to the base address of vma regions
1041	  resulting from mmap allocations. This value will be bounded
1042	  by the architecture's minimum and maximum supported values.
1043
1044	  This value can be changed after boot using the
1045	  /proc/sys/vm/mmap_rnd_bits tunable
1046
1047config HAVE_ARCH_MMAP_RND_COMPAT_BITS
1048	bool
1049	help
1050	  An arch should select this symbol if it supports running applications
1051	  in compatibility mode, supports setting a variable number of bits for
1052	  use in establishing the base address for mmap allocations, has MMU
1053	  enabled and provides values for both:
1054	  - ARCH_MMAP_RND_COMPAT_BITS_MIN
1055	  - ARCH_MMAP_RND_COMPAT_BITS_MAX
1056
1057config ARCH_MMAP_RND_COMPAT_BITS_MIN
1058	int
1059
1060config ARCH_MMAP_RND_COMPAT_BITS_MAX
1061	int
1062
1063config ARCH_MMAP_RND_COMPAT_BITS_DEFAULT
1064	int
1065
1066config ARCH_MMAP_RND_COMPAT_BITS
1067	int "Number of bits to use for ASLR of mmap base address for compatible applications" if EXPERT
1068	range ARCH_MMAP_RND_COMPAT_BITS_MIN ARCH_MMAP_RND_COMPAT_BITS_MAX
1069	default ARCH_MMAP_RND_COMPAT_BITS_DEFAULT if ARCH_MMAP_RND_COMPAT_BITS_DEFAULT
1070	default ARCH_MMAP_RND_COMPAT_BITS_MIN
1071	depends on HAVE_ARCH_MMAP_RND_COMPAT_BITS
1072	help
1073	  This value can be used to select the number of bits to use to
1074	  determine the random offset to the base address of vma regions
1075	  resulting from mmap allocations for compatible applications This
1076	  value will be bounded by the architecture's minimum and maximum
1077	  supported values.
1078
1079	  This value can be changed after boot using the
1080	  /proc/sys/vm/mmap_rnd_compat_bits tunable
1081
1082config HAVE_ARCH_COMPAT_MMAP_BASES
1083	bool
1084	help
1085	  This allows 64bit applications to invoke 32-bit mmap() syscall
1086	  and vice-versa 32-bit applications to call 64-bit mmap().
1087	  Required for applications doing different bitness syscalls.
1088
1089config PAGE_SIZE_LESS_THAN_64KB
1090	def_bool y
1091	depends on !ARM64_64K_PAGES
1092	depends on !IA64_PAGE_SIZE_64KB
1093	depends on !PAGE_SIZE_64KB
1094	depends on !PARISC_PAGE_SIZE_64KB
1095	depends on PAGE_SIZE_LESS_THAN_256KB
1096
1097config PAGE_SIZE_LESS_THAN_256KB
1098	def_bool y
1099	depends on !PAGE_SIZE_256KB
1100
1101# This allows to use a set of generic functions to determine mmap base
1102# address by giving priority to top-down scheme only if the process
1103# is not in legacy mode (compat task, unlimited stack size or
1104# sysctl_legacy_va_layout).
1105# Architecture that selects this option can provide its own version of:
1106# - STACK_RND_MASK
1107config ARCH_WANT_DEFAULT_TOPDOWN_MMAP_LAYOUT
1108	bool
1109	depends on MMU
1110	select ARCH_HAS_ELF_RANDOMIZE
1111
1112config HAVE_OBJTOOL
1113	bool
1114
1115config HAVE_JUMP_LABEL_HACK
1116	bool
1117
1118config HAVE_NOINSTR_HACK
1119	bool
1120
1121config HAVE_NOINSTR_VALIDATION
1122	bool
1123
1124config HAVE_UACCESS_VALIDATION
1125	bool
1126	select OBJTOOL
1127
1128config HAVE_STACK_VALIDATION
1129	bool
1130	help
1131	  Architecture supports objtool compile-time frame pointer rule
1132	  validation.
1133
1134config HAVE_RELIABLE_STACKTRACE
1135	bool
1136	help
1137	  Architecture has either save_stack_trace_tsk_reliable() or
1138	  arch_stack_walk_reliable() function which only returns a stack trace
1139	  if it can guarantee the trace is reliable.
1140
1141config HAVE_ARCH_HASH
1142	bool
1143	default n
1144	help
1145	  If this is set, the architecture provides an <asm/hash.h>
1146	  file which provides platform-specific implementations of some
1147	  functions in <linux/hash.h> or fs/namei.c.
1148
1149config HAVE_ARCH_NVRAM_OPS
1150	bool
1151
1152config ISA_BUS_API
1153	def_bool ISA
1154
1155#
1156# ABI hall of shame
1157#
1158config CLONE_BACKWARDS
1159	bool
1160	help
1161	  Architecture has tls passed as the 4th argument of clone(2),
1162	  not the 5th one.
1163
1164config CLONE_BACKWARDS2
1165	bool
1166	help
1167	  Architecture has the first two arguments of clone(2) swapped.
1168
1169config CLONE_BACKWARDS3
1170	bool
1171	help
1172	  Architecture has tls passed as the 3rd argument of clone(2),
1173	  not the 5th one.
1174
1175config ODD_RT_SIGACTION
1176	bool
1177	help
1178	  Architecture has unusual rt_sigaction(2) arguments
1179
1180config OLD_SIGSUSPEND
1181	bool
1182	help
1183	  Architecture has old sigsuspend(2) syscall, of one-argument variety
1184
1185config OLD_SIGSUSPEND3
1186	bool
1187	help
1188	  Even weirder antique ABI - three-argument sigsuspend(2)
1189
1190config OLD_SIGACTION
1191	bool
1192	help
1193	  Architecture has old sigaction(2) syscall.  Nope, not the same
1194	  as OLD_SIGSUSPEND | OLD_SIGSUSPEND3 - alpha has sigsuspend(2),
1195	  but fairly different variant of sigaction(2), thanks to OSF/1
1196	  compatibility...
1197
1198config COMPAT_OLD_SIGACTION
1199	bool
1200
1201config COMPAT_32BIT_TIME
1202	bool "Provide system calls for 32-bit time_t"
1203	default !64BIT || COMPAT
1204	help
1205	  This enables 32 bit time_t support in addition to 64 bit time_t support.
1206	  This is relevant on all 32-bit architectures, and 64-bit architectures
1207	  as part of compat syscall handling.
1208
1209config ARCH_NO_PREEMPT
1210	bool
1211
1212config ARCH_SUPPORTS_RT
1213	bool
1214
1215config CPU_NO_EFFICIENT_FFS
1216	def_bool n
1217
1218config HAVE_ARCH_VMAP_STACK
1219	def_bool n
1220	help
1221	  An arch should select this symbol if it can support kernel stacks
1222	  in vmalloc space.  This means:
1223
1224	  - vmalloc space must be large enough to hold many kernel stacks.
1225	    This may rule out many 32-bit architectures.
1226
1227	  - Stacks in vmalloc space need to work reliably.  For example, if
1228	    vmap page tables are created on demand, either this mechanism
1229	    needs to work while the stack points to a virtual address with
1230	    unpopulated page tables or arch code (switch_to() and switch_mm(),
1231	    most likely) needs to ensure that the stack's page table entries
1232	    are populated before running on a possibly unpopulated stack.
1233
1234	  - If the stack overflows into a guard page, something reasonable
1235	    should happen.  The definition of "reasonable" is flexible, but
1236	    instantly rebooting without logging anything would be unfriendly.
1237
1238config VMAP_STACK
1239	default y
1240	bool "Use a virtually-mapped stack"
1241	depends on HAVE_ARCH_VMAP_STACK
1242	depends on !KASAN || KASAN_HW_TAGS || KASAN_VMALLOC
1243	help
1244	  Enable this if you want the use virtually-mapped kernel stacks
1245	  with guard pages.  This causes kernel stack overflows to be
1246	  caught immediately rather than causing difficult-to-diagnose
1247	  corruption.
1248
1249	  To use this with software KASAN modes, the architecture must support
1250	  backing virtual mappings with real shadow memory, and KASAN_VMALLOC
1251	  must be enabled.
1252
1253config HAVE_ARCH_RANDOMIZE_KSTACK_OFFSET
1254	def_bool n
1255	help
1256	  An arch should select this symbol if it can support kernel stack
1257	  offset randomization with calls to add_random_kstack_offset()
1258	  during syscall entry and choose_random_kstack_offset() during
1259	  syscall exit. Careful removal of -fstack-protector-strong and
1260	  -fstack-protector should also be applied to the entry code and
1261	  closely examined, as the artificial stack bump looks like an array
1262	  to the compiler, so it will attempt to add canary checks regardless
1263	  of the static branch state.
1264
1265config RANDOMIZE_KSTACK_OFFSET
1266	bool "Support for randomizing kernel stack offset on syscall entry" if EXPERT
1267	default y
1268	depends on HAVE_ARCH_RANDOMIZE_KSTACK_OFFSET
1269	depends on INIT_STACK_NONE || !CC_IS_CLANG || CLANG_VERSION >= 140000
1270	help
1271	  The kernel stack offset can be randomized (after pt_regs) by
1272	  roughly 5 bits of entropy, frustrating memory corruption
1273	  attacks that depend on stack address determinism or
1274	  cross-syscall address exposures.
1275
1276	  The feature is controlled via the "randomize_kstack_offset=on/off"
1277	  kernel boot param, and if turned off has zero overhead due to its use
1278	  of static branches (see JUMP_LABEL).
1279
1280	  If unsure, say Y.
1281
1282config RANDOMIZE_KSTACK_OFFSET_DEFAULT
1283	bool "Default state of kernel stack offset randomization"
1284	depends on RANDOMIZE_KSTACK_OFFSET
1285	help
1286	  Kernel stack offset randomization is controlled by kernel boot param
1287	  "randomize_kstack_offset=on/off", and this config chooses the default
1288	  boot state.
1289
1290config ARCH_OPTIONAL_KERNEL_RWX
1291	def_bool n
1292
1293config ARCH_OPTIONAL_KERNEL_RWX_DEFAULT
1294	def_bool n
1295
1296config ARCH_HAS_STRICT_KERNEL_RWX
1297	def_bool n
1298
1299config STRICT_KERNEL_RWX
1300	bool "Make kernel text and rodata read-only" if ARCH_OPTIONAL_KERNEL_RWX
1301	depends on ARCH_HAS_STRICT_KERNEL_RWX
1302	default !ARCH_OPTIONAL_KERNEL_RWX || ARCH_OPTIONAL_KERNEL_RWX_DEFAULT
1303	help
1304	  If this is set, kernel text and rodata memory will be made read-only,
1305	  and non-text memory will be made non-executable. This provides
1306	  protection against certain security exploits (e.g. executing the heap
1307	  or modifying text)
1308
1309	  These features are considered standard security practice these days.
1310	  You should say Y here in almost all cases.
1311
1312config ARCH_HAS_STRICT_MODULE_RWX
1313	def_bool n
1314
1315config STRICT_MODULE_RWX
1316	bool "Set loadable kernel module data as NX and text as RO" if ARCH_OPTIONAL_KERNEL_RWX
1317	depends on ARCH_HAS_STRICT_MODULE_RWX && MODULES
1318	default !ARCH_OPTIONAL_KERNEL_RWX || ARCH_OPTIONAL_KERNEL_RWX_DEFAULT
1319	help
1320	  If this is set, module text and rodata memory will be made read-only,
1321	  and non-text memory will be made non-executable. This provides
1322	  protection against certain security exploits (e.g. writing to text)
1323
1324# select if the architecture provides an asm/dma-direct.h header
1325config ARCH_HAS_PHYS_TO_DMA
1326	bool
1327
1328config HAVE_ARCH_COMPILER_H
1329	bool
1330	help
1331	  An architecture can select this if it provides an
1332	  asm/compiler.h header that should be included after
1333	  linux/compiler-*.h in order to override macro definitions that those
1334	  headers generally provide.
1335
1336config HAVE_ARCH_PREL32_RELOCATIONS
1337	bool
1338	help
1339	  May be selected by an architecture if it supports place-relative
1340	  32-bit relocations, both in the toolchain and in the module loader,
1341	  in which case relative references can be used in special sections
1342	  for PCI fixup, initcalls etc which are only half the size on 64 bit
1343	  architectures, and don't require runtime relocation on relocatable
1344	  kernels.
1345
1346config ARCH_USE_MEMREMAP_PROT
1347	bool
1348
1349config LOCK_EVENT_COUNTS
1350	bool "Locking event counts collection"
1351	depends on DEBUG_FS
1352	help
1353	  Enable light-weight counting of various locking related events
1354	  in the system with minimal performance impact. This reduces
1355	  the chance of application behavior change because of timing
1356	  differences. The counts are reported via debugfs.
1357
1358# Select if the architecture has support for applying RELR relocations.
1359config ARCH_HAS_RELR
1360	bool
1361
1362config RELR
1363	bool "Use RELR relocation packing"
1364	depends on ARCH_HAS_RELR && TOOLS_SUPPORT_RELR
1365	default y
1366	help
1367	  Store the kernel's dynamic relocations in the RELR relocation packing
1368	  format. Requires a compatible linker (LLD supports this feature), as
1369	  well as compatible NM and OBJCOPY utilities (llvm-nm and llvm-objcopy
1370	  are compatible).
1371
1372config ARCH_HAS_MEM_ENCRYPT
1373	bool
1374
1375config ARCH_HAS_CC_PLATFORM
1376	bool
1377
1378config HAVE_SPARSE_SYSCALL_NR
1379	bool
1380	help
1381	  An architecture should select this if its syscall numbering is sparse
1382	  to save space. For example, MIPS architecture has a syscall array with
1383	  entries at 4000, 5000 and 6000 locations. This option turns on syscall
1384	  related optimizations for a given architecture.
1385
1386config ARCH_HAS_VDSO_DATA
1387	bool
1388
1389config HAVE_STATIC_CALL
1390	bool
1391
1392config HAVE_STATIC_CALL_INLINE
1393	bool
1394	depends on HAVE_STATIC_CALL
1395	select OBJTOOL
1396
1397config HAVE_PREEMPT_DYNAMIC
1398	bool
1399
1400config HAVE_PREEMPT_DYNAMIC_CALL
1401	bool
1402	depends on HAVE_STATIC_CALL
1403	select HAVE_PREEMPT_DYNAMIC
1404	help
1405	  An architecture should select this if it can handle the preemption
1406	  model being selected at boot time using static calls.
1407
1408	  Where an architecture selects HAVE_STATIC_CALL_INLINE, any call to a
1409	  preemption function will be patched directly.
1410
1411	  Where an architecture does not select HAVE_STATIC_CALL_INLINE, any
1412	  call to a preemption function will go through a trampoline, and the
1413	  trampoline will be patched.
1414
1415	  It is strongly advised to support inline static call to avoid any
1416	  overhead.
1417
1418config HAVE_PREEMPT_DYNAMIC_KEY
1419	bool
1420	depends on HAVE_ARCH_JUMP_LABEL
1421	select HAVE_PREEMPT_DYNAMIC
1422	help
1423	  An architecture should select this if it can handle the preemption
1424	  model being selected at boot time using static keys.
1425
1426	  Each preemption function will be given an early return based on a
1427	  static key. This should have slightly lower overhead than non-inline
1428	  static calls, as this effectively inlines each trampoline into the
1429	  start of its callee. This may avoid redundant work, and may
1430	  integrate better with CFI schemes.
1431
1432	  This will have greater overhead than using inline static calls as
1433	  the call to the preemption function cannot be entirely elided.
1434
1435config ARCH_WANT_LD_ORPHAN_WARN
1436	bool
1437	help
1438	  An arch should select this symbol once all linker sections are explicitly
1439	  included, size-asserted, or discarded in the linker scripts. This is
1440	  important because we never want expected sections to be placed heuristically
1441	  by the linker, since the locations of such sections can change between linker
1442	  versions.
1443
1444config HAVE_ARCH_PFN_VALID
1445	bool
1446
1447config ARCH_SUPPORTS_DEBUG_PAGEALLOC
1448	bool
1449
1450config ARCH_SUPPORTS_PAGE_TABLE_CHECK
1451	bool
1452
1453config ARCH_SPLIT_ARG64
1454	bool
1455	help
1456	  If a 32-bit architecture requires 64-bit arguments to be split into
1457	  pairs of 32-bit arguments, select this option.
1458
1459config ARCH_HAS_ELFCORE_COMPAT
1460	bool
1461
1462config ARCH_HAS_PARANOID_L1D_FLUSH
1463	bool
1464
1465config ARCH_HAVE_TRACE_MMIO_ACCESS
1466	bool
1467
1468config DYNAMIC_SIGFRAME
1469	bool
1470
1471# Select, if arch has a named attribute group bound to NUMA device nodes.
1472config HAVE_ARCH_NODE_DEV_GROUP
1473	bool
1474
1475config ARCH_HAS_NONLEAF_PMD_YOUNG
1476	bool
1477	help
1478	  Architectures that select this option are capable of setting the
1479	  accessed bit in non-leaf PMD entries when using them as part of linear
1480	  address translations. Page table walkers that clear the accessed bit
1481	  may use this capability to reduce their search space.
1482
1483source "kernel/gcov/Kconfig"
1484
1485source "scripts/gcc-plugins/Kconfig"
1486
1487config FUNCTION_ALIGNMENT_4B
1488	bool
1489
1490config FUNCTION_ALIGNMENT_8B
1491	bool
1492
1493config FUNCTION_ALIGNMENT_16B
1494	bool
1495
1496config FUNCTION_ALIGNMENT_32B
1497	bool
1498
1499config FUNCTION_ALIGNMENT_64B
1500	bool
1501
1502config FUNCTION_ALIGNMENT
1503	int
1504	default 64 if FUNCTION_ALIGNMENT_64B
1505	default 32 if FUNCTION_ALIGNMENT_32B
1506	default 16 if FUNCTION_ALIGNMENT_16B
1507	default 8 if FUNCTION_ALIGNMENT_8B
1508	default 4 if FUNCTION_ALIGNMENT_4B
1509	default 0
1510
1511endmenu
1512