xref: /openbmc/linux/arch/Kconfig (revision cde2f928)
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
37# Selected by HOTPLUG_CORE_SYNC_DEAD or HOTPLUG_CORE_SYNC_FULL
38config HOTPLUG_CORE_SYNC
39	bool
40
41# Basic CPU dead synchronization selected by architecture
42config HOTPLUG_CORE_SYNC_DEAD
43	bool
44	select HOTPLUG_CORE_SYNC
45
46# Full CPU synchronization with alive state selected by architecture
47config HOTPLUG_CORE_SYNC_FULL
48	bool
49	select HOTPLUG_CORE_SYNC_DEAD if HOTPLUG_CPU
50	select HOTPLUG_CORE_SYNC
51
52config HOTPLUG_SPLIT_STARTUP
53	bool
54	select HOTPLUG_CORE_SYNC_FULL
55
56config HOTPLUG_PARALLEL
57	bool
58	select HOTPLUG_SPLIT_STARTUP
59
60config GENERIC_ENTRY
61	bool
62
63config KPROBES
64	bool "Kprobes"
65	depends on MODULES
66	depends on HAVE_KPROBES
67	select KALLSYMS
68	select TASKS_RCU if PREEMPTION
69	help
70	  Kprobes allows you to trap at almost any kernel address and
71	  execute a callback function.  register_kprobe() establishes
72	  a probepoint and specifies the callback.  Kprobes is useful
73	  for kernel debugging, non-intrusive instrumentation and testing.
74	  If in doubt, say "N".
75
76config JUMP_LABEL
77	bool "Optimize very unlikely/likely branches"
78	depends on HAVE_ARCH_JUMP_LABEL
79	select OBJTOOL if HAVE_JUMP_LABEL_HACK
80	help
81	  This option enables a transparent branch optimization that
82	  makes certain almost-always-true or almost-always-false branch
83	  conditions even cheaper to execute within the kernel.
84
85	  Certain performance-sensitive kernel code, such as trace points,
86	  scheduler functionality, networking code and KVM have such
87	  branches and include support for this optimization technique.
88
89	  If it is detected that the compiler has support for "asm goto",
90	  the kernel will compile such branches with just a nop
91	  instruction. When the condition flag is toggled to true, the
92	  nop will be converted to a jump instruction to execute the
93	  conditional block of instructions.
94
95	  This technique lowers overhead and stress on the branch prediction
96	  of the processor and generally makes the kernel faster. The update
97	  of the condition is slower, but those are always very rare.
98
99	  ( On 32-bit x86, the necessary options added to the compiler
100	    flags may increase the size of the kernel slightly. )
101
102config STATIC_KEYS_SELFTEST
103	bool "Static key selftest"
104	depends on JUMP_LABEL
105	help
106	  Boot time self-test of the branch patching code.
107
108config STATIC_CALL_SELFTEST
109	bool "Static call selftest"
110	depends on HAVE_STATIC_CALL
111	help
112	  Boot time self-test of the call patching code.
113
114config OPTPROBES
115	def_bool y
116	depends on KPROBES && HAVE_OPTPROBES
117	select TASKS_RCU if PREEMPTION
118
119config KPROBES_ON_FTRACE
120	def_bool y
121	depends on KPROBES && HAVE_KPROBES_ON_FTRACE
122	depends on DYNAMIC_FTRACE_WITH_REGS
123	help
124	  If function tracer is enabled and the arch supports full
125	  passing of pt_regs to function tracing, then kprobes can
126	  optimize on top of function tracing.
127
128config UPROBES
129	def_bool n
130	depends on ARCH_SUPPORTS_UPROBES
131	help
132	  Uprobes is the user-space counterpart to kprobes: they
133	  enable instrumentation applications (such as 'perf probe')
134	  to establish unintrusive probes in user-space binaries and
135	  libraries, by executing handler functions when the probes
136	  are hit by user-space applications.
137
138	  ( These probes come in the form of single-byte breakpoints,
139	    managed by the kernel and kept transparent to the probed
140	    application. )
141
142config HAVE_64BIT_ALIGNED_ACCESS
143	def_bool 64BIT && !HAVE_EFFICIENT_UNALIGNED_ACCESS
144	help
145	  Some architectures require 64 bit accesses to be 64 bit
146	  aligned, which also requires structs containing 64 bit values
147	  to be 64 bit aligned too. This includes some 32 bit
148	  architectures which can do 64 bit accesses, as well as 64 bit
149	  architectures without unaligned access.
150
151	  This symbol should be selected by an architecture if 64 bit
152	  accesses are required to be 64 bit aligned in this way even
153	  though it is not a 64 bit architecture.
154
155	  See Documentation/core-api/unaligned-memory-access.rst for
156	  more information on the topic of unaligned memory accesses.
157
158config HAVE_EFFICIENT_UNALIGNED_ACCESS
159	bool
160	help
161	  Some architectures are unable to perform unaligned accesses
162	  without the use of get_unaligned/put_unaligned. Others are
163	  unable to perform such accesses efficiently (e.g. trap on
164	  unaligned access and require fixing it up in the exception
165	  handler.)
166
167	  This symbol should be selected by an architecture if it can
168	  perform unaligned accesses efficiently to allow different
169	  code paths to be selected for these cases. Some network
170	  drivers, for example, could opt to not fix up alignment
171	  problems with received packets if doing so would not help
172	  much.
173
174	  See Documentation/core-api/unaligned-memory-access.rst for more
175	  information on the topic of unaligned memory accesses.
176
177config ARCH_USE_BUILTIN_BSWAP
178	bool
179	help
180	  Modern versions of GCC (since 4.4) have builtin functions
181	  for handling byte-swapping. Using these, instead of the old
182	  inline assembler that the architecture code provides in the
183	  __arch_bswapXX() macros, allows the compiler to see what's
184	  happening and offers more opportunity for optimisation. In
185	  particular, the compiler will be able to combine the byteswap
186	  with a nearby load or store and use load-and-swap or
187	  store-and-swap instructions if the architecture has them. It
188	  should almost *never* result in code which is worse than the
189	  hand-coded assembler in <asm/swab.h>.  But just in case it
190	  does, the use of the builtins is optional.
191
192	  Any architecture with load-and-swap or store-and-swap
193	  instructions should set this. And it shouldn't hurt to set it
194	  on architectures that don't have such instructions.
195
196config KRETPROBES
197	def_bool y
198	depends on KPROBES && (HAVE_KRETPROBES || HAVE_RETHOOK)
199
200config KRETPROBE_ON_RETHOOK
201	def_bool y
202	depends on HAVE_RETHOOK
203	depends on KRETPROBES
204	select RETHOOK
205
206config USER_RETURN_NOTIFIER
207	bool
208	depends on HAVE_USER_RETURN_NOTIFIER
209	help
210	  Provide a kernel-internal notification when a cpu is about to
211	  switch to user mode.
212
213config HAVE_IOREMAP_PROT
214	bool
215
216config HAVE_KPROBES
217	bool
218
219config HAVE_KRETPROBES
220	bool
221
222config HAVE_OPTPROBES
223	bool
224
225config HAVE_KPROBES_ON_FTRACE
226	bool
227
228config ARCH_CORRECT_STACKTRACE_ON_KRETPROBE
229	bool
230	help
231	  Since kretprobes modifies return address on the stack, the
232	  stacktrace may see the kretprobe trampoline address instead
233	  of correct one. If the architecture stacktrace code and
234	  unwinder can adjust such entries, select this configuration.
235
236config HAVE_FUNCTION_ERROR_INJECTION
237	bool
238
239config HAVE_NMI
240	bool
241
242config HAVE_FUNCTION_DESCRIPTORS
243	bool
244
245config TRACE_IRQFLAGS_SUPPORT
246	bool
247
248config TRACE_IRQFLAGS_NMI_SUPPORT
249	bool
250
251#
252# An arch should select this if it provides all these things:
253#
254#	task_pt_regs()		in asm/processor.h or asm/ptrace.h
255#	arch_has_single_step()	if there is hardware single-step support
256#	arch_has_block_step()	if there is hardware block-step support
257#	asm/syscall.h		supplying asm-generic/syscall.h interface
258#	linux/regset.h		user_regset interfaces
259#	CORE_DUMP_USE_REGSET	#define'd in linux/elf.h
260#	TIF_SYSCALL_TRACE	calls ptrace_report_syscall_{entry,exit}
261#	TIF_NOTIFY_RESUME	calls resume_user_mode_work()
262#
263config HAVE_ARCH_TRACEHOOK
264	bool
265
266config HAVE_DMA_CONTIGUOUS
267	bool
268
269config GENERIC_SMP_IDLE_THREAD
270	bool
271
272config GENERIC_IDLE_POLL_SETUP
273	bool
274
275config ARCH_HAS_FORTIFY_SOURCE
276	bool
277	help
278	  An architecture should select this when it can successfully
279	  build and run with CONFIG_FORTIFY_SOURCE.
280
281#
282# Select if the arch provides a historic keepinit alias for the retain_initrd
283# command line option
284#
285config ARCH_HAS_KEEPINITRD
286	bool
287
288# Select if arch has all set_memory_ro/rw/x/nx() functions in asm/cacheflush.h
289config ARCH_HAS_SET_MEMORY
290	bool
291
292# Select if arch has all set_direct_map_invalid/default() functions
293config ARCH_HAS_SET_DIRECT_MAP
294	bool
295
296#
297# Select if the architecture provides the arch_dma_set_uncached symbol to
298# either provide an uncached segment alias for a DMA allocation, or
299# to remap the page tables in place.
300#
301config ARCH_HAS_DMA_SET_UNCACHED
302	bool
303
304#
305# Select if the architectures provides the arch_dma_clear_uncached symbol
306# to undo an in-place page table remap for uncached access.
307#
308config ARCH_HAS_DMA_CLEAR_UNCACHED
309	bool
310
311config ARCH_HAS_CPU_FINALIZE_INIT
312	bool
313
314# Select if arch init_task must go in the __init_task_data section
315config ARCH_TASK_STRUCT_ON_STACK
316	bool
317
318# Select if arch has its private alloc_task_struct() function
319config ARCH_TASK_STRUCT_ALLOCATOR
320	bool
321
322config HAVE_ARCH_THREAD_STRUCT_WHITELIST
323	bool
324	depends on !ARCH_TASK_STRUCT_ALLOCATOR
325	help
326	  An architecture should select this to provide hardened usercopy
327	  knowledge about what region of the thread_struct should be
328	  whitelisted for copying to userspace. Normally this is only the
329	  FPU registers. Specifically, arch_thread_struct_whitelist()
330	  should be implemented. Without this, the entire thread_struct
331	  field in task_struct will be left whitelisted.
332
333# Select if arch has its private alloc_thread_stack() function
334config ARCH_THREAD_STACK_ALLOCATOR
335	bool
336
337# Select if arch wants to size task_struct dynamically via arch_task_struct_size:
338config ARCH_WANTS_DYNAMIC_TASK_STRUCT
339	bool
340
341config ARCH_WANTS_NO_INSTR
342	bool
343	help
344	  An architecture should select this if the noinstr macro is being used on
345	  functions to denote that the toolchain should avoid instrumenting such
346	  functions and is required for correctness.
347
348config ARCH_32BIT_OFF_T
349	bool
350	depends on !64BIT
351	help
352	  All new 32-bit architectures should have 64-bit off_t type on
353	  userspace side which corresponds to the loff_t kernel type. This
354	  is the requirement for modern ABIs. Some existing architectures
355	  still support 32-bit off_t. This option is enabled for all such
356	  architectures explicitly.
357
358# Selected by 64 bit architectures which have a 32 bit f_tinode in struct ustat
359config ARCH_32BIT_USTAT_F_TINODE
360	bool
361
362config HAVE_ASM_MODVERSIONS
363	bool
364	help
365	  This symbol should be selected by an architecture if it provides
366	  <asm/asm-prototypes.h> to support the module versioning for symbols
367	  exported from assembly code.
368
369config HAVE_REGS_AND_STACK_ACCESS_API
370	bool
371	help
372	  This symbol should be selected by an architecture if it supports
373	  the API needed to access registers and stack entries from pt_regs,
374	  declared in asm/ptrace.h
375	  For example the kprobes-based event tracer needs this API.
376
377config HAVE_RSEQ
378	bool
379	depends on HAVE_REGS_AND_STACK_ACCESS_API
380	help
381	  This symbol should be selected by an architecture if it
382	  supports an implementation of restartable sequences.
383
384config HAVE_RUST
385	bool
386	help
387	  This symbol should be selected by an architecture if it
388	  supports Rust.
389
390config HAVE_FUNCTION_ARG_ACCESS_API
391	bool
392	help
393	  This symbol should be selected by an architecture if it supports
394	  the API needed to access function arguments from pt_regs,
395	  declared in asm/ptrace.h
396
397config HAVE_HW_BREAKPOINT
398	bool
399	depends on PERF_EVENTS
400
401config HAVE_MIXED_BREAKPOINTS_REGS
402	bool
403	depends on HAVE_HW_BREAKPOINT
404	help
405	  Depending on the arch implementation of hardware breakpoints,
406	  some of them have separate registers for data and instruction
407	  breakpoints addresses, others have mixed registers to store
408	  them but define the access type in a control register.
409	  Select this option if your arch implements breakpoints under the
410	  latter fashion.
411
412config HAVE_USER_RETURN_NOTIFIER
413	bool
414
415config HAVE_PERF_EVENTS_NMI
416	bool
417	help
418	  System hardware can generate an NMI using the perf event
419	  subsystem.  Also has support for calculating CPU cycle events
420	  to determine how many clock cycles in a given period.
421
422config HAVE_HARDLOCKUP_DETECTOR_PERF
423	bool
424	depends on HAVE_PERF_EVENTS_NMI
425	help
426	  The arch chooses to use the generic perf-NMI-based hardlockup
427	  detector. Must define HAVE_PERF_EVENTS_NMI.
428
429config HAVE_HARDLOCKUP_DETECTOR_ARCH
430	bool
431	help
432	  The arch provides its own hardlockup detector implementation instead
433	  of the generic ones.
434
435	  It uses the same command line parameters, and sysctl interface,
436	  as the generic hardlockup detectors.
437
438config HAVE_PERF_REGS
439	bool
440	help
441	  Support selective register dumps for perf events. This includes
442	  bit-mapping of each registers and a unique architecture id.
443
444config HAVE_PERF_USER_STACK_DUMP
445	bool
446	help
447	  Support user stack dumps for perf event samples. This needs
448	  access to the user stack pointer which is not unified across
449	  architectures.
450
451config HAVE_ARCH_JUMP_LABEL
452	bool
453
454config HAVE_ARCH_JUMP_LABEL_RELATIVE
455	bool
456
457config MMU_GATHER_TABLE_FREE
458	bool
459
460config MMU_GATHER_RCU_TABLE_FREE
461	bool
462	select MMU_GATHER_TABLE_FREE
463
464config MMU_GATHER_PAGE_SIZE
465	bool
466
467config MMU_GATHER_NO_RANGE
468	bool
469	select MMU_GATHER_MERGE_VMAS
470
471config MMU_GATHER_NO_FLUSH_CACHE
472	bool
473
474config MMU_GATHER_MERGE_VMAS
475	bool
476
477config MMU_GATHER_NO_GATHER
478	bool
479	depends on MMU_GATHER_TABLE_FREE
480
481config ARCH_WANT_IRQS_OFF_ACTIVATE_MM
482	bool
483	help
484	  Temporary select until all architectures can be converted to have
485	  irqs disabled over activate_mm. Architectures that do IPI based TLB
486	  shootdowns should enable this.
487
488# Use normal mm refcounting for MMU_LAZY_TLB kernel thread references.
489# MMU_LAZY_TLB_REFCOUNT=n can improve the scalability of context switching
490# to/from kernel threads when the same mm is running on a lot of CPUs (a large
491# multi-threaded application), by reducing contention on the mm refcount.
492#
493# This can be disabled if the architecture ensures no CPUs are using an mm as a
494# "lazy tlb" beyond its final refcount (i.e., by the time __mmdrop frees the mm
495# or its kernel page tables). This could be arranged by arch_exit_mmap(), or
496# final exit(2) TLB flush, for example.
497#
498# To implement this, an arch *must*:
499# Ensure the _lazy_tlb variants of mmgrab/mmdrop are used when manipulating
500# the lazy tlb reference of a kthread's ->active_mm (non-arch code has been
501# converted already).
502config MMU_LAZY_TLB_REFCOUNT
503	def_bool y
504	depends on !MMU_LAZY_TLB_SHOOTDOWN
505
506# This option allows MMU_LAZY_TLB_REFCOUNT=n. It ensures no CPUs are using an
507# mm as a lazy tlb beyond its last reference count, by shooting down these
508# users before the mm is deallocated. __mmdrop() first IPIs all CPUs that may
509# be using the mm as a lazy tlb, so that they may switch themselves to using
510# init_mm for their active mm. mm_cpumask(mm) is used to determine which CPUs
511# may be using mm as a lazy tlb mm.
512#
513# To implement this, an arch *must*:
514# - At the time of the final mmdrop of the mm, ensure mm_cpumask(mm) contains
515#   at least all possible CPUs in which the mm is lazy.
516# - It must meet the requirements for MMU_LAZY_TLB_REFCOUNT=n (see above).
517config MMU_LAZY_TLB_SHOOTDOWN
518	bool
519
520config ARCH_HAVE_NMI_SAFE_CMPXCHG
521	bool
522
523config ARCH_HAS_NMI_SAFE_THIS_CPU_OPS
524	bool
525
526config HAVE_ALIGNED_STRUCT_PAGE
527	bool
528	help
529	  This makes sure that struct pages are double word aligned and that
530	  e.g. the SLUB allocator can perform double word atomic operations
531	  on a struct page for better performance. However selecting this
532	  might increase the size of a struct page by a word.
533
534config HAVE_CMPXCHG_LOCAL
535	bool
536
537config HAVE_CMPXCHG_DOUBLE
538	bool
539
540config ARCH_WEAK_RELEASE_ACQUIRE
541	bool
542
543config ARCH_WANT_IPC_PARSE_VERSION
544	bool
545
546config ARCH_WANT_COMPAT_IPC_PARSE_VERSION
547	bool
548
549config ARCH_WANT_OLD_COMPAT_IPC
550	select ARCH_WANT_COMPAT_IPC_PARSE_VERSION
551	bool
552
553config HAVE_ARCH_SECCOMP
554	bool
555	help
556	  An arch should select this symbol to support seccomp mode 1 (the fixed
557	  syscall policy), and must provide an overrides for __NR_seccomp_sigreturn,
558	  and compat syscalls if the asm-generic/seccomp.h defaults need adjustment:
559	  - __NR_seccomp_read_32
560	  - __NR_seccomp_write_32
561	  - __NR_seccomp_exit_32
562	  - __NR_seccomp_sigreturn_32
563
564config HAVE_ARCH_SECCOMP_FILTER
565	bool
566	select HAVE_ARCH_SECCOMP
567	help
568	  An arch should select this symbol if it provides all of these things:
569	  - all the requirements for HAVE_ARCH_SECCOMP
570	  - syscall_get_arch()
571	  - syscall_get_arguments()
572	  - syscall_rollback()
573	  - syscall_set_return_value()
574	  - SIGSYS siginfo_t support
575	  - secure_computing is called from a ptrace_event()-safe context
576	  - secure_computing return value is checked and a return value of -1
577	    results in the system call being skipped immediately.
578	  - seccomp syscall wired up
579	  - if !HAVE_SPARSE_SYSCALL_NR, have SECCOMP_ARCH_NATIVE,
580	    SECCOMP_ARCH_NATIVE_NR, SECCOMP_ARCH_NATIVE_NAME defined. If
581	    COMPAT is supported, have the SECCOMP_ARCH_COMPAT* defines too.
582
583config SECCOMP
584	prompt "Enable seccomp to safely execute untrusted bytecode"
585	def_bool y
586	depends on HAVE_ARCH_SECCOMP
587	help
588	  This kernel feature is useful for number crunching applications
589	  that may need to handle untrusted bytecode during their
590	  execution. By using pipes or other transports made available
591	  to the process as file descriptors supporting the read/write
592	  syscalls, it's possible to isolate those applications in their
593	  own address space using seccomp. Once seccomp is enabled via
594	  prctl(PR_SET_SECCOMP) or the seccomp() syscall, it cannot be
595	  disabled and the task is only allowed to execute a few safe
596	  syscalls defined by each seccomp mode.
597
598	  If unsure, say Y.
599
600config SECCOMP_FILTER
601	def_bool y
602	depends on HAVE_ARCH_SECCOMP_FILTER && SECCOMP && NET
603	help
604	  Enable tasks to build secure computing environments defined
605	  in terms of Berkeley Packet Filter programs which implement
606	  task-defined system call filtering polices.
607
608	  See Documentation/userspace-api/seccomp_filter.rst for details.
609
610config SECCOMP_CACHE_DEBUG
611	bool "Show seccomp filter cache status in /proc/pid/seccomp_cache"
612	depends on SECCOMP_FILTER && !HAVE_SPARSE_SYSCALL_NR
613	depends on PROC_FS
614	help
615	  This enables the /proc/pid/seccomp_cache interface to monitor
616	  seccomp cache data. The file format is subject to change. Reading
617	  the file requires CAP_SYS_ADMIN.
618
619	  This option is for debugging only. Enabling presents the risk that
620	  an adversary may be able to infer the seccomp filter logic.
621
622	  If unsure, say N.
623
624config HAVE_ARCH_STACKLEAK
625	bool
626	help
627	  An architecture should select this if it has the code which
628	  fills the used part of the kernel stack with the STACKLEAK_POISON
629	  value before returning from system calls.
630
631config HAVE_STACKPROTECTOR
632	bool
633	help
634	  An arch should select this symbol if:
635	  - it has implemented a stack canary (e.g. __stack_chk_guard)
636
637config STACKPROTECTOR
638	bool "Stack Protector buffer overflow detection"
639	depends on HAVE_STACKPROTECTOR
640	depends on $(cc-option,-fstack-protector)
641	default y
642	help
643	  This option turns on the "stack-protector" GCC feature. This
644	  feature puts, at the beginning of functions, a canary value on
645	  the stack just before the return address, and validates
646	  the value just before actually returning.  Stack based buffer
647	  overflows (that need to overwrite this return address) now also
648	  overwrite the canary, which gets detected and the attack is then
649	  neutralized via a kernel panic.
650
651	  Functions will have the stack-protector canary logic added if they
652	  have an 8-byte or larger character array on the stack.
653
654	  This feature requires gcc version 4.2 or above, or a distribution
655	  gcc with the feature backported ("-fstack-protector").
656
657	  On an x86 "defconfig" build, this feature adds canary checks to
658	  about 3% of all kernel functions, which increases kernel code size
659	  by about 0.3%.
660
661config STACKPROTECTOR_STRONG
662	bool "Strong Stack Protector"
663	depends on STACKPROTECTOR
664	depends on $(cc-option,-fstack-protector-strong)
665	default y
666	help
667	  Functions will have the stack-protector canary logic added in any
668	  of the following conditions:
669
670	  - local variable's address used as part of the right hand side of an
671	    assignment or function argument
672	  - local variable is an array (or union containing an array),
673	    regardless of array type or length
674	  - uses register local variables
675
676	  This feature requires gcc version 4.9 or above, or a distribution
677	  gcc with the feature backported ("-fstack-protector-strong").
678
679	  On an x86 "defconfig" build, this feature adds canary checks to
680	  about 20% of all kernel functions, which increases the kernel code
681	  size by about 2%.
682
683config ARCH_SUPPORTS_SHADOW_CALL_STACK
684	bool
685	help
686	  An architecture should select this if it supports the compiler's
687	  Shadow Call Stack and implements runtime support for shadow stack
688	  switching.
689
690config SHADOW_CALL_STACK
691	bool "Shadow Call Stack"
692	depends on ARCH_SUPPORTS_SHADOW_CALL_STACK
693	depends on DYNAMIC_FTRACE_WITH_ARGS || DYNAMIC_FTRACE_WITH_REGS || !FUNCTION_GRAPH_TRACER
694	help
695	  This option enables the compiler's Shadow Call Stack, which
696	  uses a shadow stack to protect function return addresses from
697	  being overwritten by an attacker. More information can be found
698	  in the compiler's documentation:
699
700	  - Clang: https://clang.llvm.org/docs/ShadowCallStack.html
701	  - GCC: https://gcc.gnu.org/onlinedocs/gcc/Instrumentation-Options.html#Instrumentation-Options
702
703	  Note that security guarantees in the kernel differ from the
704	  ones documented for user space. The kernel must store addresses
705	  of shadow stacks in memory, which means an attacker capable of
706	  reading and writing arbitrary memory may be able to locate them
707	  and hijack control flow by modifying the stacks.
708
709config DYNAMIC_SCS
710	bool
711	help
712	  Set by the arch code if it relies on code patching to insert the
713	  shadow call stack push and pop instructions rather than on the
714	  compiler.
715
716config LTO
717	bool
718	help
719	  Selected if the kernel will be built using the compiler's LTO feature.
720
721config LTO_CLANG
722	bool
723	select LTO
724	help
725	  Selected if the kernel will be built using Clang's LTO feature.
726
727config ARCH_SUPPORTS_LTO_CLANG
728	bool
729	help
730	  An architecture should select this option if it supports:
731	  - compiling with Clang,
732	  - compiling inline assembly with Clang's integrated assembler,
733	  - and linking with LLD.
734
735config ARCH_SUPPORTS_LTO_CLANG_THIN
736	bool
737	help
738	  An architecture should select this option if it can support Clang's
739	  ThinLTO mode.
740
741config HAS_LTO_CLANG
742	def_bool y
743	depends on CC_IS_CLANG && LD_IS_LLD && AS_IS_LLVM
744	depends on $(success,$(NM) --help | head -n 1 | grep -qi llvm)
745	depends on $(success,$(AR) --help | head -n 1 | grep -qi llvm)
746	depends on ARCH_SUPPORTS_LTO_CLANG
747	depends on !FTRACE_MCOUNT_USE_RECORDMCOUNT
748	depends on !KASAN || KASAN_HW_TAGS
749	depends on !GCOV_KERNEL
750	help
751	  The compiler and Kconfig options support building with Clang's
752	  LTO.
753
754choice
755	prompt "Link Time Optimization (LTO)"
756	default LTO_NONE
757	help
758	  This option enables Link Time Optimization (LTO), which allows the
759	  compiler to optimize binaries globally.
760
761	  If unsure, select LTO_NONE. Note that LTO is very resource-intensive
762	  so it's disabled by default.
763
764config LTO_NONE
765	bool "None"
766	help
767	  Build the kernel normally, without Link Time Optimization (LTO).
768
769config LTO_CLANG_FULL
770	bool "Clang Full LTO (EXPERIMENTAL)"
771	depends on HAS_LTO_CLANG
772	depends on !COMPILE_TEST
773	select LTO_CLANG
774	help
775	  This option enables Clang's full Link Time Optimization (LTO), which
776	  allows the compiler to optimize the kernel globally. If you enable
777	  this option, the compiler generates LLVM bitcode instead of ELF
778	  object files, and the actual compilation from bitcode happens at
779	  the LTO link step, which may take several minutes depending on the
780	  kernel configuration. More information can be found from LLVM's
781	  documentation:
782
783	    https://llvm.org/docs/LinkTimeOptimization.html
784
785	  During link time, this option can use a large amount of RAM, and
786	  may take much longer than the ThinLTO option.
787
788config LTO_CLANG_THIN
789	bool "Clang ThinLTO (EXPERIMENTAL)"
790	depends on HAS_LTO_CLANG && ARCH_SUPPORTS_LTO_CLANG_THIN
791	select LTO_CLANG
792	help
793	  This option enables Clang's ThinLTO, which allows for parallel
794	  optimization and faster incremental compiles compared to the
795	  CONFIG_LTO_CLANG_FULL option. More information can be found
796	  from Clang's documentation:
797
798	    https://clang.llvm.org/docs/ThinLTO.html
799
800	  If unsure, say Y.
801endchoice
802
803config ARCH_SUPPORTS_CFI_CLANG
804	bool
805	help
806	  An architecture should select this option if it can support Clang's
807	  Control-Flow Integrity (CFI) checking.
808
809config ARCH_USES_CFI_TRAPS
810	bool
811
812config CFI_CLANG
813	bool "Use Clang's Control Flow Integrity (CFI)"
814	depends on ARCH_SUPPORTS_CFI_CLANG
815	depends on $(cc-option,-fsanitize=kcfi)
816	help
817	  This option enables Clang’s forward-edge Control Flow Integrity
818	  (CFI) checking, where the compiler injects a runtime check to each
819	  indirect function call to ensure the target is a valid function with
820	  the correct static type. This restricts possible call targets and
821	  makes it more difficult for an attacker to exploit bugs that allow
822	  the modification of stored function pointers. More information can be
823	  found from Clang's documentation:
824
825	    https://clang.llvm.org/docs/ControlFlowIntegrity.html
826
827config CFI_PERMISSIVE
828	bool "Use CFI in permissive mode"
829	depends on CFI_CLANG
830	help
831	  When selected, Control Flow Integrity (CFI) violations result in a
832	  warning instead of a kernel panic. This option should only be used
833	  for finding indirect call type mismatches during development.
834
835	  If unsure, say N.
836
837config HAVE_ARCH_WITHIN_STACK_FRAMES
838	bool
839	help
840	  An architecture should select this if it can walk the kernel stack
841	  frames to determine if an object is part of either the arguments
842	  or local variables (i.e. that it excludes saved return addresses,
843	  and similar) by implementing an inline arch_within_stack_frames(),
844	  which is used by CONFIG_HARDENED_USERCOPY.
845
846config HAVE_CONTEXT_TRACKING_USER
847	bool
848	help
849	  Provide kernel/user boundaries probes necessary for subsystems
850	  that need it, such as userspace RCU extended quiescent state.
851	  Syscalls need to be wrapped inside user_exit()-user_enter(), either
852	  optimized behind static key or through the slow path using TIF_NOHZ
853	  flag. Exceptions handlers must be wrapped as well. Irqs are already
854	  protected inside ct_irq_enter/ct_irq_exit() but preemption or signal
855	  handling on irq exit still need to be protected.
856
857config HAVE_CONTEXT_TRACKING_USER_OFFSTACK
858	bool
859	help
860	  Architecture neither relies on exception_enter()/exception_exit()
861	  nor on schedule_user(). Also preempt_schedule_notrace() and
862	  preempt_schedule_irq() can't be called in a preemptible section
863	  while context tracking is CONTEXT_USER. This feature reflects a sane
864	  entry implementation where the following requirements are met on
865	  critical entry code, ie: before user_exit() or after user_enter():
866
867	  - Critical entry code isn't preemptible (or better yet:
868	    not interruptible).
869	  - No use of RCU read side critical sections, unless ct_nmi_enter()
870	    got called.
871	  - No use of instrumentation, unless instrumentation_begin() got
872	    called.
873
874config HAVE_TIF_NOHZ
875	bool
876	help
877	  Arch relies on TIF_NOHZ and syscall slow path to implement context
878	  tracking calls to user_enter()/user_exit().
879
880config HAVE_VIRT_CPU_ACCOUNTING
881	bool
882
883config HAVE_VIRT_CPU_ACCOUNTING_IDLE
884	bool
885	help
886	  Architecture has its own way to account idle CPU time and therefore
887	  doesn't implement vtime_account_idle().
888
889config ARCH_HAS_SCALED_CPUTIME
890	bool
891
892config HAVE_VIRT_CPU_ACCOUNTING_GEN
893	bool
894	default y if 64BIT
895	help
896	  With VIRT_CPU_ACCOUNTING_GEN, cputime_t becomes 64-bit.
897	  Before enabling this option, arch code must be audited
898	  to ensure there are no races in concurrent read/write of
899	  cputime_t. For example, reading/writing 64-bit cputime_t on
900	  some 32-bit arches may require multiple accesses, so proper
901	  locking is needed to protect against concurrent accesses.
902
903config HAVE_IRQ_TIME_ACCOUNTING
904	bool
905	help
906	  Archs need to ensure they use a high enough resolution clock to
907	  support irq time accounting and then call enable_sched_clock_irqtime().
908
909config HAVE_MOVE_PUD
910	bool
911	help
912	  Architectures that select this are able to move page tables at the
913	  PUD level. If there are only 3 page table levels, the move effectively
914	  happens at the PGD level.
915
916config HAVE_MOVE_PMD
917	bool
918	help
919	  Archs that select this are able to move page tables at the PMD level.
920
921config HAVE_ARCH_TRANSPARENT_HUGEPAGE
922	bool
923
924config HAVE_ARCH_TRANSPARENT_HUGEPAGE_PUD
925	bool
926
927config HAVE_ARCH_HUGE_VMAP
928	bool
929
930#
931#  Archs that select this would be capable of PMD-sized vmaps (i.e.,
932#  arch_vmap_pmd_supported() returns true). The VM_ALLOW_HUGE_VMAP flag
933#  must be used to enable allocations to use hugepages.
934#
935config HAVE_ARCH_HUGE_VMALLOC
936	depends on HAVE_ARCH_HUGE_VMAP
937	bool
938
939config ARCH_WANT_HUGE_PMD_SHARE
940	bool
941
942config HAVE_ARCH_SOFT_DIRTY
943	bool
944
945config HAVE_MOD_ARCH_SPECIFIC
946	bool
947	help
948	  The arch uses struct mod_arch_specific to store data.  Many arches
949	  just need a simple module loader without arch specific data - those
950	  should not enable this.
951
952config MODULES_USE_ELF_RELA
953	bool
954	help
955	  Modules only use ELF RELA relocations.  Modules with ELF REL
956	  relocations will give an error.
957
958config MODULES_USE_ELF_REL
959	bool
960	help
961	  Modules only use ELF REL relocations.  Modules with ELF RELA
962	  relocations will give an error.
963
964config ARCH_WANTS_MODULES_DATA_IN_VMALLOC
965	bool
966	help
967	  For architectures like powerpc/32 which have constraints on module
968	  allocation and need to allocate module data outside of module area.
969
970config HAVE_IRQ_EXIT_ON_IRQ_STACK
971	bool
972	help
973	  Architecture doesn't only execute the irq handler on the irq stack
974	  but also irq_exit(). This way we can process softirqs on this irq
975	  stack instead of switching to a new one when we call __do_softirq()
976	  in the end of an hardirq.
977	  This spares a stack switch and improves cache usage on softirq
978	  processing.
979
980config HAVE_SOFTIRQ_ON_OWN_STACK
981	bool
982	help
983	  Architecture provides a function to run __do_softirq() on a
984	  separate stack.
985
986config SOFTIRQ_ON_OWN_STACK
987	def_bool HAVE_SOFTIRQ_ON_OWN_STACK && !PREEMPT_RT
988
989config ALTERNATE_USER_ADDRESS_SPACE
990	bool
991	help
992	  Architectures set this when the CPU uses separate address
993	  spaces for kernel and user space pointers. In this case, the
994	  access_ok() check on a __user pointer is skipped.
995
996config PGTABLE_LEVELS
997	int
998	default 2
999
1000config ARCH_HAS_ELF_RANDOMIZE
1001	bool
1002	help
1003	  An architecture supports choosing randomized locations for
1004	  stack, mmap, brk, and ET_DYN. Defined functions:
1005	  - arch_mmap_rnd()
1006	  - arch_randomize_brk()
1007
1008config HAVE_ARCH_MMAP_RND_BITS
1009	bool
1010	help
1011	  An arch should select this symbol if it supports setting a variable
1012	  number of bits for use in establishing the base address for mmap
1013	  allocations, has MMU enabled and provides values for both:
1014	  - ARCH_MMAP_RND_BITS_MIN
1015	  - ARCH_MMAP_RND_BITS_MAX
1016
1017config HAVE_EXIT_THREAD
1018	bool
1019	help
1020	  An architecture implements exit_thread.
1021
1022config ARCH_MMAP_RND_BITS_MIN
1023	int
1024
1025config ARCH_MMAP_RND_BITS_MAX
1026	int
1027
1028config ARCH_MMAP_RND_BITS_DEFAULT
1029	int
1030
1031config ARCH_MMAP_RND_BITS
1032	int "Number of bits to use for ASLR of mmap base address" if EXPERT
1033	range ARCH_MMAP_RND_BITS_MIN ARCH_MMAP_RND_BITS_MAX
1034	default ARCH_MMAP_RND_BITS_DEFAULT if ARCH_MMAP_RND_BITS_DEFAULT
1035	default ARCH_MMAP_RND_BITS_MIN
1036	depends on HAVE_ARCH_MMAP_RND_BITS
1037	help
1038	  This value can be used to select the number of bits to use to
1039	  determine the random offset to the base address of vma regions
1040	  resulting from mmap allocations. This value will be bounded
1041	  by the architecture's minimum and maximum supported values.
1042
1043	  This value can be changed after boot using the
1044	  /proc/sys/vm/mmap_rnd_bits tunable
1045
1046config HAVE_ARCH_MMAP_RND_COMPAT_BITS
1047	bool
1048	help
1049	  An arch should select this symbol if it supports running applications
1050	  in compatibility mode, supports setting a variable number of bits for
1051	  use in establishing the base address for mmap allocations, has MMU
1052	  enabled and provides values for both:
1053	  - ARCH_MMAP_RND_COMPAT_BITS_MIN
1054	  - ARCH_MMAP_RND_COMPAT_BITS_MAX
1055
1056config ARCH_MMAP_RND_COMPAT_BITS_MIN
1057	int
1058
1059config ARCH_MMAP_RND_COMPAT_BITS_MAX
1060	int
1061
1062config ARCH_MMAP_RND_COMPAT_BITS_DEFAULT
1063	int
1064
1065config ARCH_MMAP_RND_COMPAT_BITS
1066	int "Number of bits to use for ASLR of mmap base address for compatible applications" if EXPERT
1067	range ARCH_MMAP_RND_COMPAT_BITS_MIN ARCH_MMAP_RND_COMPAT_BITS_MAX
1068	default ARCH_MMAP_RND_COMPAT_BITS_DEFAULT if ARCH_MMAP_RND_COMPAT_BITS_DEFAULT
1069	default ARCH_MMAP_RND_COMPAT_BITS_MIN
1070	depends on HAVE_ARCH_MMAP_RND_COMPAT_BITS
1071	help
1072	  This value can be used to select the number of bits to use to
1073	  determine the random offset to the base address of vma regions
1074	  resulting from mmap allocations for compatible applications This
1075	  value will be bounded by the architecture's minimum and maximum
1076	  supported values.
1077
1078	  This value can be changed after boot using the
1079	  /proc/sys/vm/mmap_rnd_compat_bits tunable
1080
1081config HAVE_ARCH_COMPAT_MMAP_BASES
1082	bool
1083	help
1084	  This allows 64bit applications to invoke 32-bit mmap() syscall
1085	  and vice-versa 32-bit applications to call 64-bit mmap().
1086	  Required for applications doing different bitness syscalls.
1087
1088config PAGE_SIZE_LESS_THAN_64KB
1089	def_bool y
1090	depends on !ARM64_64K_PAGES
1091	depends on !IA64_PAGE_SIZE_64KB
1092	depends on !PAGE_SIZE_64KB
1093	depends on !PARISC_PAGE_SIZE_64KB
1094	depends on PAGE_SIZE_LESS_THAN_256KB
1095
1096config PAGE_SIZE_LESS_THAN_256KB
1097	def_bool y
1098	depends on !PAGE_SIZE_256KB
1099
1100# This allows to use a set of generic functions to determine mmap base
1101# address by giving priority to top-down scheme only if the process
1102# is not in legacy mode (compat task, unlimited stack size or
1103# sysctl_legacy_va_layout).
1104# Architecture that selects this option can provide its own version of:
1105# - STACK_RND_MASK
1106config ARCH_WANT_DEFAULT_TOPDOWN_MMAP_LAYOUT
1107	bool
1108	depends on MMU
1109	select ARCH_HAS_ELF_RANDOMIZE
1110
1111config HAVE_OBJTOOL
1112	bool
1113
1114config HAVE_JUMP_LABEL_HACK
1115	bool
1116
1117config HAVE_NOINSTR_HACK
1118	bool
1119
1120config HAVE_NOINSTR_VALIDATION
1121	bool
1122
1123config HAVE_UACCESS_VALIDATION
1124	bool
1125	select OBJTOOL
1126
1127config HAVE_STACK_VALIDATION
1128	bool
1129	help
1130	  Architecture supports objtool compile-time frame pointer rule
1131	  validation.
1132
1133config HAVE_RELIABLE_STACKTRACE
1134	bool
1135	help
1136	  Architecture has either save_stack_trace_tsk_reliable() or
1137	  arch_stack_walk_reliable() function which only returns a stack trace
1138	  if it can guarantee the trace is reliable.
1139
1140config HAVE_ARCH_HASH
1141	bool
1142	default n
1143	help
1144	  If this is set, the architecture provides an <asm/hash.h>
1145	  file which provides platform-specific implementations of some
1146	  functions in <linux/hash.h> or fs/namei.c.
1147
1148config HAVE_ARCH_NVRAM_OPS
1149	bool
1150
1151config ISA_BUS_API
1152	def_bool ISA
1153
1154#
1155# ABI hall of shame
1156#
1157config CLONE_BACKWARDS
1158	bool
1159	help
1160	  Architecture has tls passed as the 4th argument of clone(2),
1161	  not the 5th one.
1162
1163config CLONE_BACKWARDS2
1164	bool
1165	help
1166	  Architecture has the first two arguments of clone(2) swapped.
1167
1168config CLONE_BACKWARDS3
1169	bool
1170	help
1171	  Architecture has tls passed as the 3rd argument of clone(2),
1172	  not the 5th one.
1173
1174config ODD_RT_SIGACTION
1175	bool
1176	help
1177	  Architecture has unusual rt_sigaction(2) arguments
1178
1179config OLD_SIGSUSPEND
1180	bool
1181	help
1182	  Architecture has old sigsuspend(2) syscall, of one-argument variety
1183
1184config OLD_SIGSUSPEND3
1185	bool
1186	help
1187	  Even weirder antique ABI - three-argument sigsuspend(2)
1188
1189config OLD_SIGACTION
1190	bool
1191	help
1192	  Architecture has old sigaction(2) syscall.  Nope, not the same
1193	  as OLD_SIGSUSPEND | OLD_SIGSUSPEND3 - alpha has sigsuspend(2),
1194	  but fairly different variant of sigaction(2), thanks to OSF/1
1195	  compatibility...
1196
1197config COMPAT_OLD_SIGACTION
1198	bool
1199
1200config COMPAT_32BIT_TIME
1201	bool "Provide system calls for 32-bit time_t"
1202	default !64BIT || COMPAT
1203	help
1204	  This enables 32 bit time_t support in addition to 64 bit time_t support.
1205	  This is relevant on all 32-bit architectures, and 64-bit architectures
1206	  as part of compat syscall handling.
1207
1208config ARCH_NO_PREEMPT
1209	bool
1210
1211config ARCH_SUPPORTS_RT
1212	bool
1213
1214config CPU_NO_EFFICIENT_FFS
1215	def_bool n
1216
1217config HAVE_ARCH_VMAP_STACK
1218	def_bool n
1219	help
1220	  An arch should select this symbol if it can support kernel stacks
1221	  in vmalloc space.  This means:
1222
1223	  - vmalloc space must be large enough to hold many kernel stacks.
1224	    This may rule out many 32-bit architectures.
1225
1226	  - Stacks in vmalloc space need to work reliably.  For example, if
1227	    vmap page tables are created on demand, either this mechanism
1228	    needs to work while the stack points to a virtual address with
1229	    unpopulated page tables or arch code (switch_to() and switch_mm(),
1230	    most likely) needs to ensure that the stack's page table entries
1231	    are populated before running on a possibly unpopulated stack.
1232
1233	  - If the stack overflows into a guard page, something reasonable
1234	    should happen.  The definition of "reasonable" is flexible, but
1235	    instantly rebooting without logging anything would be unfriendly.
1236
1237config VMAP_STACK
1238	default y
1239	bool "Use a virtually-mapped stack"
1240	depends on HAVE_ARCH_VMAP_STACK
1241	depends on !KASAN || KASAN_HW_TAGS || KASAN_VMALLOC
1242	help
1243	  Enable this if you want the use virtually-mapped kernel stacks
1244	  with guard pages.  This causes kernel stack overflows to be
1245	  caught immediately rather than causing difficult-to-diagnose
1246	  corruption.
1247
1248	  To use this with software KASAN modes, the architecture must support
1249	  backing virtual mappings with real shadow memory, and KASAN_VMALLOC
1250	  must be enabled.
1251
1252config HAVE_ARCH_RANDOMIZE_KSTACK_OFFSET
1253	def_bool n
1254	help
1255	  An arch should select this symbol if it can support kernel stack
1256	  offset randomization with calls to add_random_kstack_offset()
1257	  during syscall entry and choose_random_kstack_offset() during
1258	  syscall exit. Careful removal of -fstack-protector-strong and
1259	  -fstack-protector should also be applied to the entry code and
1260	  closely examined, as the artificial stack bump looks like an array
1261	  to the compiler, so it will attempt to add canary checks regardless
1262	  of the static branch state.
1263
1264config RANDOMIZE_KSTACK_OFFSET
1265	bool "Support for randomizing kernel stack offset on syscall entry" if EXPERT
1266	default y
1267	depends on HAVE_ARCH_RANDOMIZE_KSTACK_OFFSET
1268	depends on INIT_STACK_NONE || !CC_IS_CLANG || CLANG_VERSION >= 140000
1269	help
1270	  The kernel stack offset can be randomized (after pt_regs) by
1271	  roughly 5 bits of entropy, frustrating memory corruption
1272	  attacks that depend on stack address determinism or
1273	  cross-syscall address exposures.
1274
1275	  The feature is controlled via the "randomize_kstack_offset=on/off"
1276	  kernel boot param, and if turned off has zero overhead due to its use
1277	  of static branches (see JUMP_LABEL).
1278
1279	  If unsure, say Y.
1280
1281config RANDOMIZE_KSTACK_OFFSET_DEFAULT
1282	bool "Default state of kernel stack offset randomization"
1283	depends on RANDOMIZE_KSTACK_OFFSET
1284	help
1285	  Kernel stack offset randomization is controlled by kernel boot param
1286	  "randomize_kstack_offset=on/off", and this config chooses the default
1287	  boot state.
1288
1289config ARCH_OPTIONAL_KERNEL_RWX
1290	def_bool n
1291
1292config ARCH_OPTIONAL_KERNEL_RWX_DEFAULT
1293	def_bool n
1294
1295config ARCH_HAS_STRICT_KERNEL_RWX
1296	def_bool n
1297
1298config STRICT_KERNEL_RWX
1299	bool "Make kernel text and rodata read-only" if ARCH_OPTIONAL_KERNEL_RWX
1300	depends on ARCH_HAS_STRICT_KERNEL_RWX
1301	default !ARCH_OPTIONAL_KERNEL_RWX || ARCH_OPTIONAL_KERNEL_RWX_DEFAULT
1302	help
1303	  If this is set, kernel text and rodata memory will be made read-only,
1304	  and non-text memory will be made non-executable. This provides
1305	  protection against certain security exploits (e.g. executing the heap
1306	  or modifying text)
1307
1308	  These features are considered standard security practice these days.
1309	  You should say Y here in almost all cases.
1310
1311config ARCH_HAS_STRICT_MODULE_RWX
1312	def_bool n
1313
1314config STRICT_MODULE_RWX
1315	bool "Set loadable kernel module data as NX and text as RO" if ARCH_OPTIONAL_KERNEL_RWX
1316	depends on ARCH_HAS_STRICT_MODULE_RWX && MODULES
1317	default !ARCH_OPTIONAL_KERNEL_RWX || ARCH_OPTIONAL_KERNEL_RWX_DEFAULT
1318	help
1319	  If this is set, module text and rodata memory will be made read-only,
1320	  and non-text memory will be made non-executable. This provides
1321	  protection against certain security exploits (e.g. writing to text)
1322
1323# select if the architecture provides an asm/dma-direct.h header
1324config ARCH_HAS_PHYS_TO_DMA
1325	bool
1326
1327config HAVE_ARCH_COMPILER_H
1328	bool
1329	help
1330	  An architecture can select this if it provides an
1331	  asm/compiler.h header that should be included after
1332	  linux/compiler-*.h in order to override macro definitions that those
1333	  headers generally provide.
1334
1335config HAVE_ARCH_PREL32_RELOCATIONS
1336	bool
1337	help
1338	  May be selected by an architecture if it supports place-relative
1339	  32-bit relocations, both in the toolchain and in the module loader,
1340	  in which case relative references can be used in special sections
1341	  for PCI fixup, initcalls etc which are only half the size on 64 bit
1342	  architectures, and don't require runtime relocation on relocatable
1343	  kernels.
1344
1345config ARCH_USE_MEMREMAP_PROT
1346	bool
1347
1348config LOCK_EVENT_COUNTS
1349	bool "Locking event counts collection"
1350	depends on DEBUG_FS
1351	help
1352	  Enable light-weight counting of various locking related events
1353	  in the system with minimal performance impact. This reduces
1354	  the chance of application behavior change because of timing
1355	  differences. The counts are reported via debugfs.
1356
1357# Select if the architecture has support for applying RELR relocations.
1358config ARCH_HAS_RELR
1359	bool
1360
1361config RELR
1362	bool "Use RELR relocation packing"
1363	depends on ARCH_HAS_RELR && TOOLS_SUPPORT_RELR
1364	default y
1365	help
1366	  Store the kernel's dynamic relocations in the RELR relocation packing
1367	  format. Requires a compatible linker (LLD supports this feature), as
1368	  well as compatible NM and OBJCOPY utilities (llvm-nm and llvm-objcopy
1369	  are compatible).
1370
1371config ARCH_HAS_MEM_ENCRYPT
1372	bool
1373
1374config ARCH_HAS_CC_PLATFORM
1375	bool
1376
1377config HAVE_SPARSE_SYSCALL_NR
1378	bool
1379	help
1380	  An architecture should select this if its syscall numbering is sparse
1381	  to save space. For example, MIPS architecture has a syscall array with
1382	  entries at 4000, 5000 and 6000 locations. This option turns on syscall
1383	  related optimizations for a given architecture.
1384
1385config ARCH_HAS_VDSO_DATA
1386	bool
1387
1388config HAVE_STATIC_CALL
1389	bool
1390
1391config HAVE_STATIC_CALL_INLINE
1392	bool
1393	depends on HAVE_STATIC_CALL
1394	select OBJTOOL
1395
1396config HAVE_PREEMPT_DYNAMIC
1397	bool
1398
1399config HAVE_PREEMPT_DYNAMIC_CALL
1400	bool
1401	depends on HAVE_STATIC_CALL
1402	select HAVE_PREEMPT_DYNAMIC
1403	help
1404	  An architecture should select this if it can handle the preemption
1405	  model being selected at boot time using static calls.
1406
1407	  Where an architecture selects HAVE_STATIC_CALL_INLINE, any call to a
1408	  preemption function will be patched directly.
1409
1410	  Where an architecture does not select HAVE_STATIC_CALL_INLINE, any
1411	  call to a preemption function will go through a trampoline, and the
1412	  trampoline will be patched.
1413
1414	  It is strongly advised to support inline static call to avoid any
1415	  overhead.
1416
1417config HAVE_PREEMPT_DYNAMIC_KEY
1418	bool
1419	depends on HAVE_ARCH_JUMP_LABEL
1420	select HAVE_PREEMPT_DYNAMIC
1421	help
1422	  An architecture should select this if it can handle the preemption
1423	  model being selected at boot time using static keys.
1424
1425	  Each preemption function will be given an early return based on a
1426	  static key. This should have slightly lower overhead than non-inline
1427	  static calls, as this effectively inlines each trampoline into the
1428	  start of its callee. This may avoid redundant work, and may
1429	  integrate better with CFI schemes.
1430
1431	  This will have greater overhead than using inline static calls as
1432	  the call to the preemption function cannot be entirely elided.
1433
1434config ARCH_WANT_LD_ORPHAN_WARN
1435	bool
1436	help
1437	  An arch should select this symbol once all linker sections are explicitly
1438	  included, size-asserted, or discarded in the linker scripts. This is
1439	  important because we never want expected sections to be placed heuristically
1440	  by the linker, since the locations of such sections can change between linker
1441	  versions.
1442
1443config HAVE_ARCH_PFN_VALID
1444	bool
1445
1446config ARCH_SUPPORTS_DEBUG_PAGEALLOC
1447	bool
1448
1449config ARCH_SUPPORTS_PAGE_TABLE_CHECK
1450	bool
1451
1452config ARCH_SPLIT_ARG64
1453	bool
1454	help
1455	  If a 32-bit architecture requires 64-bit arguments to be split into
1456	  pairs of 32-bit arguments, select this option.
1457
1458config ARCH_HAS_ELFCORE_COMPAT
1459	bool
1460
1461config ARCH_HAS_PARANOID_L1D_FLUSH
1462	bool
1463
1464config ARCH_HAVE_TRACE_MMIO_ACCESS
1465	bool
1466
1467config DYNAMIC_SIGFRAME
1468	bool
1469
1470# Select, if arch has a named attribute group bound to NUMA device nodes.
1471config HAVE_ARCH_NODE_DEV_GROUP
1472	bool
1473
1474config ARCH_HAS_NONLEAF_PMD_YOUNG
1475	bool
1476	help
1477	  Architectures that select this option are capable of setting the
1478	  accessed bit in non-leaf PMD entries when using them as part of linear
1479	  address translations. Page table walkers that clear the accessed bit
1480	  may use this capability to reduce their search space.
1481
1482source "kernel/gcov/Kconfig"
1483
1484source "scripts/gcc-plugins/Kconfig"
1485
1486config FUNCTION_ALIGNMENT_4B
1487	bool
1488
1489config FUNCTION_ALIGNMENT_8B
1490	bool
1491
1492config FUNCTION_ALIGNMENT_16B
1493	bool
1494
1495config FUNCTION_ALIGNMENT_32B
1496	bool
1497
1498config FUNCTION_ALIGNMENT_64B
1499	bool
1500
1501config FUNCTION_ALIGNMENT
1502	int
1503	default 64 if FUNCTION_ALIGNMENT_64B
1504	default 32 if FUNCTION_ALIGNMENT_32B
1505	default 16 if FUNCTION_ALIGNMENT_16B
1506	default 8 if FUNCTION_ALIGNMENT_8B
1507	default 4 if FUNCTION_ALIGNMENT_4B
1508	default 0
1509
1510endmenu
1511