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 HOTPLUG_SMT
 
 28	bool
 
 29
 30config GENERIC_ENTRY
 31       bool
 32
 33config OPROFILE
 34	tristate "OProfile system profiling"
 35	depends on PROFILING
 36	depends on HAVE_OPROFILE
 37	select RING_BUFFER
 38	select RING_BUFFER_ALLOW_SWAP
 39	help
 40	  OProfile is a profiling system capable of profiling the
 41	  whole system, include the kernel, kernel modules, libraries,
 42	  and applications.
 43
 44	  If unsure, say N.
 45
 46config OPROFILE_EVENT_MULTIPLEX
 47	bool "OProfile multiplexing support (EXPERIMENTAL)"
 48	default n
 49	depends on OPROFILE && X86
 50	help
 51	  The number of hardware counters is limited. The multiplexing
 52	  feature enables OProfile to gather more events than counters
 53	  are provided by the hardware. This is realized by switching
 54	  between events at a user specified time interval.
 55
 56	  If unsure, say N.
 
 
 57
 58config HAVE_OPROFILE
 59	bool
 
 60
 61config OPROFILE_NMI_TIMER
 62	def_bool y
 63	depends on PERF_EVENTS && HAVE_PERF_EVENTS_NMI && !PPC64
 64
 65config KPROBES
 66	bool "Kprobes"
 67	depends on MODULES
 68	depends on HAVE_KPROBES
 69	select KALLSYMS
 
 70	help
 71	  Kprobes allows you to trap at almost any kernel address and
 72	  execute a callback function.  register_kprobe() establishes
 73	  a probepoint and specifies the callback.  Kprobes is useful
 74	  for kernel debugging, non-intrusive instrumentation and testing.
 75	  If in doubt, say "N".
 76
 77config JUMP_LABEL
 78	bool "Optimize very unlikely/likely branches"
 79	depends on HAVE_ARCH_JUMP_LABEL
 80	depends on CC_HAS_ASM_GOTO
 81	help
 82	 This option enables a transparent branch optimization that
 83	 makes certain almost-always-true or almost-always-false branch
 84	 conditions even cheaper to execute within the kernel.
 85
 86	 Certain performance-sensitive kernel code, such as trace points,
 87	 scheduler functionality, networking code and KVM have such
 88	 branches and include support for this optimization technique.
 89
 90	 If it is detected that the compiler has support for "asm goto",
 91	 the kernel will compile such branches with just a nop
 92	 instruction. When the condition flag is toggled to true, the
 93	 nop will be converted to a jump instruction to execute the
 94	 conditional block of instructions.
 95
 96	 This technique lowers overhead and stress on the branch prediction
 97	 of the processor and generally makes the kernel faster. The update
 98	 of the condition is slower, but those are always very rare.
 99
100	 ( On 32-bit x86, the necessary options added to the compiler
101	   flags may increase the size of the kernel slightly. )
102
103config STATIC_KEYS_SELFTEST
104	bool "Static key selftest"
105	depends on JUMP_LABEL
106	help
107	  Boot time self-test of the branch patching code.
108
 
 
 
 
 
 
109config OPTPROBES
110	def_bool y
111	depends on KPROBES && HAVE_OPTPROBES
112	select TASKS_RCU if PREEMPTION
113
114config KPROBES_ON_FTRACE
115	def_bool y
116	depends on KPROBES && HAVE_KPROBES_ON_FTRACE
117	depends on DYNAMIC_FTRACE_WITH_REGS
118	help
119	 If function tracer is enabled and the arch supports full
120	 passing of pt_regs to function tracing, then kprobes can
121	 optimize on top of function tracing.
122
123config UPROBES
124	def_bool n
125	depends on ARCH_SUPPORTS_UPROBES
126	help
127	  Uprobes is the user-space counterpart to kprobes: they
128	  enable instrumentation applications (such as 'perf probe')
129	  to establish unintrusive probes in user-space binaries and
130	  libraries, by executing handler functions when the probes
131	  are hit by user-space applications.
132
133	  ( These probes come in the form of single-byte breakpoints,
134	    managed by the kernel and kept transparent to the probed
135	    application. )
136
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
137config HAVE_EFFICIENT_UNALIGNED_ACCESS
138	bool
139	help
140	  Some architectures are unable to perform unaligned accesses
141	  without the use of get_unaligned/put_unaligned. Others are
142	  unable to perform such accesses efficiently (e.g. trap on
143	  unaligned access and require fixing it up in the exception
144	  handler.)
145
146	  This symbol should be selected by an architecture if it can
147	  perform unaligned accesses efficiently to allow different
148	  code paths to be selected for these cases. Some network
149	  drivers, for example, could opt to not fix up alignment
150	  problems with received packets if doing so would not help
151	  much.
152
153	  See Documentation/core-api/unaligned-memory-access.rst for more
154	  information on the topic of unaligned memory accesses.
155
156config ARCH_USE_BUILTIN_BSWAP
157	bool
158	help
159	 Modern versions of GCC (since 4.4) have builtin functions
160	 for handling byte-swapping. Using these, instead of the old
161	 inline assembler that the architecture code provides in the
162	 __arch_bswapXX() macros, allows the compiler to see what's
163	 happening and offers more opportunity for optimisation. In
164	 particular, the compiler will be able to combine the byteswap
165	 with a nearby load or store and use load-and-swap or
166	 store-and-swap instructions if the architecture has them. It
167	 should almost *never* result in code which is worse than the
168	 hand-coded assembler in <asm/swab.h>.  But just in case it
169	 does, the use of the builtins is optional.
170
171	 Any architecture with load-and-swap or store-and-swap
172	 instructions should set this. And it shouldn't hurt to set it
173	 on architectures that don't have such instructions.
174
175config KRETPROBES
176	def_bool y
177	depends on KPROBES && HAVE_KRETPROBES
 
 
 
 
 
 
178
179config USER_RETURN_NOTIFIER
180	bool
181	depends on HAVE_USER_RETURN_NOTIFIER
182	help
183	  Provide a kernel-internal notification when a cpu is about to
184	  switch to user mode.
185
186config HAVE_IOREMAP_PROT
187	bool
188
189config HAVE_KPROBES
190	bool
191
192config HAVE_KRETPROBES
193	bool
194
195config HAVE_OPTPROBES
196	bool
197
198config HAVE_KPROBES_ON_FTRACE
199	bool
200
 
 
 
 
 
 
 
 
201config HAVE_FUNCTION_ERROR_INJECTION
202	bool
203
204config HAVE_NMI
205	bool
206
 
 
 
 
 
 
 
 
 
207#
208# An arch should select this if it provides all these things:
209#
210#	task_pt_regs()		in asm/processor.h or asm/ptrace.h
211#	arch_has_single_step()	if there is hardware single-step support
212#	arch_has_block_step()	if there is hardware block-step support
213#	asm/syscall.h		supplying asm-generic/syscall.h interface
214#	linux/regset.h		user_regset interfaces
215#	CORE_DUMP_USE_REGSET	#define'd in linux/elf.h
216#	TIF_SYSCALL_TRACE	calls tracehook_report_syscall_{entry,exit}
217#	TIF_NOTIFY_RESUME	calls tracehook_notify_resume()
218#	signal delivery		calls tracehook_signal_handler()
219#
220config HAVE_ARCH_TRACEHOOK
221	bool
222
223config HAVE_DMA_CONTIGUOUS
224	bool
225
226config GENERIC_SMP_IDLE_THREAD
227	bool
228
229config GENERIC_IDLE_POLL_SETUP
230	bool
231
232config ARCH_HAS_FORTIFY_SOURCE
233	bool
234	help
235	  An architecture should select this when it can successfully
236	  build and run with CONFIG_FORTIFY_SOURCE.
237
238#
239# Select if the arch provides a historic keepinit alias for the retain_initrd
240# command line option
241#
242config ARCH_HAS_KEEPINITRD
243	bool
244
245# Select if arch has all set_memory_ro/rw/x/nx() functions in asm/cacheflush.h
246config ARCH_HAS_SET_MEMORY
247	bool
248
249# Select if arch has all set_direct_map_invalid/default() functions
250config ARCH_HAS_SET_DIRECT_MAP
251	bool
252
253#
254# Select if the architecture provides the arch_dma_set_uncached symbol to
255# either provide an uncached segement alias for a DMA allocation, or
256# to remap the page tables in place.
257#
258config ARCH_HAS_DMA_SET_UNCACHED
259	bool
260
261#
262# Select if the architectures provides the arch_dma_clear_uncached symbol
263# to undo an in-place page table remap for uncached access.
264#
265config ARCH_HAS_DMA_CLEAR_UNCACHED
266	bool
267
268# Select if arch init_task must go in the __init_task_data section
269config ARCH_TASK_STRUCT_ON_STACK
270	bool
271
272# Select if arch has its private alloc_task_struct() function
273config ARCH_TASK_STRUCT_ALLOCATOR
274	bool
 
275
276config HAVE_ARCH_THREAD_STRUCT_WHITELIST
277	bool
278	depends on !ARCH_TASK_STRUCT_ALLOCATOR
279	help
280	  An architecture should select this to provide hardened usercopy
281	  knowledge about what region of the thread_struct should be
282	  whitelisted for copying to userspace. Normally this is only the
283	  FPU registers. Specifically, arch_thread_struct_whitelist()
284	  should be implemented. Without this, the entire thread_struct
285	  field in task_struct will be left whitelisted.
286
287# Select if arch has its private alloc_thread_stack() function
288config ARCH_THREAD_STACK_ALLOCATOR
289	bool
290
291# Select if arch wants to size task_struct dynamically via arch_task_struct_size:
292config ARCH_WANTS_DYNAMIC_TASK_STRUCT
293	bool
294
 
 
 
 
 
 
 
295config ARCH_32BIT_OFF_T
296	bool
297	depends on !64BIT
298	help
299	  All new 32-bit architectures should have 64-bit off_t type on
300	  userspace side which corresponds to the loff_t kernel type. This
301	  is the requirement for modern ABIs. Some existing architectures
302	  still support 32-bit off_t. This option is enabled for all such
303	  architectures explicitly.
304
 
 
 
 
305config HAVE_ASM_MODVERSIONS
306	bool
307	help
308	  This symbol should be selected by an architecure if it provides
309	  <asm/asm-prototypes.h> to support the module versioning for symbols
310	  exported from assembly code.
311
312config HAVE_REGS_AND_STACK_ACCESS_API
313	bool
314	help
315	  This symbol should be selected by an architecure if it supports
316	  the API needed to access registers and stack entries from pt_regs,
317	  declared in asm/ptrace.h
318	  For example the kprobes-based event tracer needs this API.
319
320config HAVE_RSEQ
321	bool
322	depends on HAVE_REGS_AND_STACK_ACCESS_API
323	help
324	  This symbol should be selected by an architecture if it
325	  supports an implementation of restartable sequences.
326
 
 
 
 
 
 
327config HAVE_FUNCTION_ARG_ACCESS_API
328	bool
329	help
330	  This symbol should be selected by an architecure if it supports
331	  the API needed to access function arguments from pt_regs,
332	  declared in asm/ptrace.h
333
334config HAVE_HW_BREAKPOINT
335	bool
336	depends on PERF_EVENTS
337
338config HAVE_MIXED_BREAKPOINTS_REGS
339	bool
340	depends on HAVE_HW_BREAKPOINT
341	help
342	  Depending on the arch implementation of hardware breakpoints,
343	  some of them have separate registers for data and instruction
344	  breakpoints addresses, others have mixed registers to store
345	  them but define the access type in a control register.
346	  Select this option if your arch implements breakpoints under the
347	  latter fashion.
348
349config HAVE_USER_RETURN_NOTIFIER
350	bool
351
352config HAVE_PERF_EVENTS_NMI
353	bool
354	help
355	  System hardware can generate an NMI using the perf event
356	  subsystem.  Also has support for calculating CPU cycle events
357	  to determine how many clock cycles in a given period.
358
359config HAVE_HARDLOCKUP_DETECTOR_PERF
360	bool
361	depends on HAVE_PERF_EVENTS_NMI
362	help
363	  The arch chooses to use the generic perf-NMI-based hardlockup
364	  detector. Must define HAVE_PERF_EVENTS_NMI.
365
366config HAVE_NMI_WATCHDOG
367	depends on HAVE_NMI
368	bool
369	help
370	  The arch provides a low level NMI watchdog. It provides
371	  asm/nmi.h, and defines its own arch_touch_nmi_watchdog().
372
373config HAVE_HARDLOCKUP_DETECTOR_ARCH
374	bool
375	select HAVE_NMI_WATCHDOG
376	help
377	  The arch chooses to provide its own hardlockup detector, which is
378	  a superset of the HAVE_NMI_WATCHDOG. It also conforms to config
379	  interfaces and parameters provided by hardlockup detector subsystem.
 
 
380
381config HAVE_PERF_REGS
382	bool
383	help
384	  Support selective register dumps for perf events. This includes
385	  bit-mapping of each registers and a unique architecture id.
386
387config HAVE_PERF_USER_STACK_DUMP
388	bool
389	help
390	  Support user stack dumps for perf event samples. This needs
391	  access to the user stack pointer which is not unified across
392	  architectures.
393
394config HAVE_ARCH_JUMP_LABEL
395	bool
396
397config HAVE_ARCH_JUMP_LABEL_RELATIVE
398	bool
399
400config MMU_GATHER_TABLE_FREE
401	bool
402
403config MMU_GATHER_RCU_TABLE_FREE
404	bool
405	select MMU_GATHER_TABLE_FREE
406
407config MMU_GATHER_PAGE_SIZE
408	bool
409
410config MMU_GATHER_NO_RANGE
411	bool
 
 
 
 
 
 
 
412
413config MMU_GATHER_NO_GATHER
414	bool
415	depends on MMU_GATHER_TABLE_FREE
416
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
417config ARCH_HAVE_NMI_SAFE_CMPXCHG
418	bool
419
 
 
 
420config HAVE_ALIGNED_STRUCT_PAGE
421	bool
422	help
423	  This makes sure that struct pages are double word aligned and that
424	  e.g. the SLUB allocator can perform double word atomic operations
425	  on a struct page for better performance. However selecting this
426	  might increase the size of a struct page by a word.
427
428config HAVE_CMPXCHG_LOCAL
429	bool
430
431config HAVE_CMPXCHG_DOUBLE
432	bool
433
434config ARCH_WEAK_RELEASE_ACQUIRE
435	bool
436
437config ARCH_WANT_IPC_PARSE_VERSION
438	bool
439
440config ARCH_WANT_COMPAT_IPC_PARSE_VERSION
441	bool
442
443config ARCH_WANT_OLD_COMPAT_IPC
444	select ARCH_WANT_COMPAT_IPC_PARSE_VERSION
445	bool
446
 
 
 
 
 
 
 
 
 
 
 
447config HAVE_ARCH_SECCOMP_FILTER
448	bool
 
449	help
450	  An arch should select this symbol if it provides all of these things:
 
451	  - syscall_get_arch()
452	  - syscall_get_arguments()
453	  - syscall_rollback()
454	  - syscall_set_return_value()
455	  - SIGSYS siginfo_t support
456	  - secure_computing is called from a ptrace_event()-safe context
457	  - secure_computing return value is checked and a return value of -1
458	    results in the system call being skipped immediately.
459	  - seccomp syscall wired up
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
460
461config SECCOMP_FILTER
462	def_bool y
463	depends on HAVE_ARCH_SECCOMP_FILTER && SECCOMP && NET
464	help
465	  Enable tasks to build secure computing environments defined
466	  in terms of Berkeley Packet Filter programs which implement
467	  task-defined system call filtering polices.
468
469	  See Documentation/userspace-api/seccomp_filter.rst for details.
470
 
 
 
 
 
 
 
 
 
 
 
 
 
 
471config HAVE_ARCH_STACKLEAK
472	bool
473	help
474	  An architecture should select this if it has the code which
475	  fills the used part of the kernel stack with the STACKLEAK_POISON
476	  value before returning from system calls.
477
478config HAVE_STACKPROTECTOR
479	bool
480	help
481	  An arch should select this symbol if:
482	  - it has implemented a stack canary (e.g. __stack_chk_guard)
483
484config STACKPROTECTOR
485	bool "Stack Protector buffer overflow detection"
486	depends on HAVE_STACKPROTECTOR
487	depends on $(cc-option,-fstack-protector)
488	default y
489	help
490	  This option turns on the "stack-protector" GCC feature. This
491	  feature puts, at the beginning of functions, a canary value on
492	  the stack just before the return address, and validates
493	  the value just before actually returning.  Stack based buffer
494	  overflows (that need to overwrite this return address) now also
495	  overwrite the canary, which gets detected and the attack is then
496	  neutralized via a kernel panic.
497
498	  Functions will have the stack-protector canary logic added if they
499	  have an 8-byte or larger character array on the stack.
500
501	  This feature requires gcc version 4.2 or above, or a distribution
502	  gcc with the feature backported ("-fstack-protector").
503
504	  On an x86 "defconfig" build, this feature adds canary checks to
505	  about 3% of all kernel functions, which increases kernel code size
506	  by about 0.3%.
507
508config STACKPROTECTOR_STRONG
509	bool "Strong Stack Protector"
510	depends on STACKPROTECTOR
511	depends on $(cc-option,-fstack-protector-strong)
512	default y
513	help
514	  Functions will have the stack-protector canary logic added in any
515	  of the following conditions:
516
517	  - local variable's address used as part of the right hand side of an
518	    assignment or function argument
519	  - local variable is an array (or union containing an array),
520	    regardless of array type or length
521	  - uses register local variables
522
523	  This feature requires gcc version 4.9 or above, or a distribution
524	  gcc with the feature backported ("-fstack-protector-strong").
525
526	  On an x86 "defconfig" build, this feature adds canary checks to
527	  about 20% of all kernel functions, which increases the kernel code
528	  size by about 2%.
529
530config ARCH_SUPPORTS_SHADOW_CALL_STACK
531	bool
532	help
533	  An architecture should select this if it supports Clang's Shadow
534	  Call Stack and implements runtime support for shadow stack
535	  switching.
536
537config SHADOW_CALL_STACK
538	bool "Clang Shadow Call Stack"
539	depends on CC_IS_CLANG && ARCH_SUPPORTS_SHADOW_CALL_STACK
540	depends on DYNAMIC_FTRACE_WITH_REGS || !FUNCTION_GRAPH_TRACER
541	help
542	  This option enables Clang's Shadow Call Stack, which uses a
543	  shadow stack to protect function return addresses from being
544	  overwritten by an attacker. More information can be found in
545	  Clang's documentation:
 
546
547	    https://clang.llvm.org/docs/ShadowCallStack.html
 
548
549	  Note that security guarantees in the kernel differ from the
550	  ones documented for user space. The kernel must store addresses
551	  of shadow stacks in memory, which means an attacker capable of
552	  reading and writing arbitrary memory may be able to locate them
553	  and hijack control flow by modifying the stacks.
554
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
555config HAVE_ARCH_WITHIN_STACK_FRAMES
556	bool
557	help
558	  An architecture should select this if it can walk the kernel stack
559	  frames to determine if an object is part of either the arguments
560	  or local variables (i.e. that it excludes saved return addresses,
561	  and similar) by implementing an inline arch_within_stack_frames(),
562	  which is used by CONFIG_HARDENED_USERCOPY.
563
564config HAVE_CONTEXT_TRACKING
565	bool
566	help
567	  Provide kernel/user boundaries probes necessary for subsystems
568	  that need it, such as userspace RCU extended quiescent state.
569	  Syscalls need to be wrapped inside user_exit()-user_enter(), either
570	  optimized behind static key or through the slow path using TIF_NOHZ
571	  flag. Exceptions handlers must be wrapped as well. Irqs are already
572	  protected inside rcu_irq_enter/rcu_irq_exit() but preemption or signal
573	  handling on irq exit still need to be protected.
574
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
575config HAVE_TIF_NOHZ
576	bool
577	help
578	  Arch relies on TIF_NOHZ and syscall slow path to implement context
579	  tracking calls to user_enter()/user_exit().
580
581config HAVE_VIRT_CPU_ACCOUNTING
582	bool
583
 
 
 
 
 
 
584config ARCH_HAS_SCALED_CPUTIME
585	bool
586
587config HAVE_VIRT_CPU_ACCOUNTING_GEN
588	bool
589	default y if 64BIT
590	help
591	  With VIRT_CPU_ACCOUNTING_GEN, cputime_t becomes 64-bit.
592	  Before enabling this option, arch code must be audited
593	  to ensure there are no races in concurrent read/write of
594	  cputime_t. For example, reading/writing 64-bit cputime_t on
595	  some 32-bit arches may require multiple accesses, so proper
596	  locking is needed to protect against concurrent accesses.
597
598
599config HAVE_IRQ_TIME_ACCOUNTING
600	bool
601	help
602	  Archs need to ensure they use a high enough resolution clock to
603	  support irq time accounting and then call enable_sched_clock_irqtime().
604
 
 
 
 
 
 
 
605config HAVE_MOVE_PMD
606	bool
607	help
608	  Archs that select this are able to move page tables at the PMD level.
609
610config HAVE_ARCH_TRANSPARENT_HUGEPAGE
611	bool
612
613config HAVE_ARCH_TRANSPARENT_HUGEPAGE_PUD
614	bool
615
616config HAVE_ARCH_HUGE_VMAP
617	bool
618
 
 
 
 
 
 
 
 
 
619config ARCH_WANT_HUGE_PMD_SHARE
620	bool
621
 
 
 
 
 
 
 
 
622config HAVE_ARCH_SOFT_DIRTY
623	bool
624
625config HAVE_MOD_ARCH_SPECIFIC
626	bool
627	help
628	  The arch uses struct mod_arch_specific to store data.  Many arches
629	  just need a simple module loader without arch specific data - those
630	  should not enable this.
631
632config MODULES_USE_ELF_RELA
633	bool
634	help
635	  Modules only use ELF RELA relocations.  Modules with ELF REL
636	  relocations will give an error.
637
638config MODULES_USE_ELF_REL
639	bool
640	help
641	  Modules only use ELF REL relocations.  Modules with ELF RELA
642	  relocations will give an error.
643
 
 
 
 
 
 
644config HAVE_IRQ_EXIT_ON_IRQ_STACK
645	bool
646	help
647	  Architecture doesn't only execute the irq handler on the irq stack
648	  but also irq_exit(). This way we can process softirqs on this irq
649	  stack instead of switching to a new one when we call __do_softirq()
650	  in the end of an hardirq.
651	  This spares a stack switch and improves cache usage on softirq
652	  processing.
653
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
654config PGTABLE_LEVELS
655	int
656	default 2
657
658config ARCH_HAS_ELF_RANDOMIZE
659	bool
660	help
661	  An architecture supports choosing randomized locations for
662	  stack, mmap, brk, and ET_DYN. Defined functions:
663	  - arch_mmap_rnd()
664	  - arch_randomize_brk()
665
666config HAVE_ARCH_MMAP_RND_BITS
667	bool
668	help
669	  An arch should select this symbol if it supports setting a variable
670	  number of bits for use in establishing the base address for mmap
671	  allocations, has MMU enabled and provides values for both:
672	  - ARCH_MMAP_RND_BITS_MIN
673	  - ARCH_MMAP_RND_BITS_MAX
674
675config HAVE_EXIT_THREAD
676	bool
677	help
678	  An architecture implements exit_thread.
679
680config ARCH_MMAP_RND_BITS_MIN
681	int
682
683config ARCH_MMAP_RND_BITS_MAX
684	int
685
686config ARCH_MMAP_RND_BITS_DEFAULT
687	int
688
689config ARCH_MMAP_RND_BITS
690	int "Number of bits to use for ASLR of mmap base address" if EXPERT
691	range ARCH_MMAP_RND_BITS_MIN ARCH_MMAP_RND_BITS_MAX
692	default ARCH_MMAP_RND_BITS_DEFAULT if ARCH_MMAP_RND_BITS_DEFAULT
693	default ARCH_MMAP_RND_BITS_MIN
694	depends on HAVE_ARCH_MMAP_RND_BITS
695	help
696	  This value can be used to select the number of bits to use to
697	  determine the random offset to the base address of vma regions
698	  resulting from mmap allocations. This value will be bounded
699	  by the architecture's minimum and maximum supported values.
700
701	  This value can be changed after boot using the
702	  /proc/sys/vm/mmap_rnd_bits tunable
703
704config HAVE_ARCH_MMAP_RND_COMPAT_BITS
705	bool
706	help
707	  An arch should select this symbol if it supports running applications
708	  in compatibility mode, supports setting a variable number of bits for
709	  use in establishing the base address for mmap allocations, has MMU
710	  enabled and provides values for both:
711	  - ARCH_MMAP_RND_COMPAT_BITS_MIN
712	  - ARCH_MMAP_RND_COMPAT_BITS_MAX
713
714config ARCH_MMAP_RND_COMPAT_BITS_MIN
715	int
716
717config ARCH_MMAP_RND_COMPAT_BITS_MAX
718	int
719
720config ARCH_MMAP_RND_COMPAT_BITS_DEFAULT
721	int
722
723config ARCH_MMAP_RND_COMPAT_BITS
724	int "Number of bits to use for ASLR of mmap base address for compatible applications" if EXPERT
725	range ARCH_MMAP_RND_COMPAT_BITS_MIN ARCH_MMAP_RND_COMPAT_BITS_MAX
726	default ARCH_MMAP_RND_COMPAT_BITS_DEFAULT if ARCH_MMAP_RND_COMPAT_BITS_DEFAULT
727	default ARCH_MMAP_RND_COMPAT_BITS_MIN
728	depends on HAVE_ARCH_MMAP_RND_COMPAT_BITS
729	help
730	  This value can be used to select the number of bits to use to
731	  determine the random offset to the base address of vma regions
732	  resulting from mmap allocations for compatible applications This
733	  value will be bounded by the architecture's minimum and maximum
734	  supported values.
735
736	  This value can be changed after boot using the
737	  /proc/sys/vm/mmap_rnd_compat_bits tunable
738
739config HAVE_ARCH_COMPAT_MMAP_BASES
740	bool
741	help
742	  This allows 64bit applications to invoke 32-bit mmap() syscall
743	  and vice-versa 32-bit applications to call 64-bit mmap().
744	  Required for applications doing different bitness syscalls.
745
 
 
 
 
 
 
 
 
 
 
 
746# This allows to use a set of generic functions to determine mmap base
747# address by giving priority to top-down scheme only if the process
748# is not in legacy mode (compat task, unlimited stack size or
749# sysctl_legacy_va_layout).
750# Architecture that selects this option can provide its own version of:
751# - STACK_RND_MASK
752config ARCH_WANT_DEFAULT_TOPDOWN_MMAP_LAYOUT
753	bool
754	depends on MMU
755	select ARCH_HAS_ELF_RANDOMIZE
756
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
757config HAVE_STACK_VALIDATION
758	bool
759	help
760	  Architecture supports the 'objtool check' host tool command, which
761	  performs compile-time stack metadata validation.
762
763config HAVE_RELIABLE_STACKTRACE
764	bool
765	help
766	  Architecture has either save_stack_trace_tsk_reliable() or
767	  arch_stack_walk_reliable() function which only returns a stack trace
768	  if it can guarantee the trace is reliable.
769
770config HAVE_ARCH_HASH
771	bool
772	default n
773	help
774	  If this is set, the architecture provides an <asm/hash.h>
775	  file which provides platform-specific implementations of some
776	  functions in <linux/hash.h> or fs/namei.c.
777
778config HAVE_ARCH_NVRAM_OPS
779	bool
780
781config ISA_BUS_API
782	def_bool ISA
783
784#
785# ABI hall of shame
786#
787config CLONE_BACKWARDS
788	bool
789	help
790	  Architecture has tls passed as the 4th argument of clone(2),
791	  not the 5th one.
792
793config CLONE_BACKWARDS2
794	bool
795	help
796	  Architecture has the first two arguments of clone(2) swapped.
797
798config CLONE_BACKWARDS3
799	bool
800	help
801	  Architecture has tls passed as the 3rd argument of clone(2),
802	  not the 5th one.
803
804config ODD_RT_SIGACTION
805	bool
806	help
807	  Architecture has unusual rt_sigaction(2) arguments
808
809config OLD_SIGSUSPEND
810	bool
811	help
812	  Architecture has old sigsuspend(2) syscall, of one-argument variety
813
814config OLD_SIGSUSPEND3
815	bool
816	help
817	  Even weirder antique ABI - three-argument sigsuspend(2)
818
819config OLD_SIGACTION
820	bool
821	help
822	  Architecture has old sigaction(2) syscall.  Nope, not the same
823	  as OLD_SIGSUSPEND | OLD_SIGSUSPEND3 - alpha has sigsuspend(2),
824	  but fairly different variant of sigaction(2), thanks to OSF/1
825	  compatibility...
826
827config COMPAT_OLD_SIGACTION
828	bool
829
830config COMPAT_32BIT_TIME
831	bool "Provide system calls for 32-bit time_t"
832	default !64BIT || COMPAT
833	help
834	  This enables 32 bit time_t support in addition to 64 bit time_t support.
835	  This is relevant on all 32-bit architectures, and 64-bit architectures
836	  as part of compat syscall handling.
837
838config ARCH_NO_PREEMPT
839	bool
840
841config ARCH_SUPPORTS_RT
842	bool
843
844config CPU_NO_EFFICIENT_FFS
845	def_bool n
846
847config HAVE_ARCH_VMAP_STACK
848	def_bool n
849	help
850	  An arch should select this symbol if it can support kernel stacks
851	  in vmalloc space.  This means:
852
853	  - vmalloc space must be large enough to hold many kernel stacks.
854	    This may rule out many 32-bit architectures.
855
856	  - Stacks in vmalloc space need to work reliably.  For example, if
857	    vmap page tables are created on demand, either this mechanism
858	    needs to work while the stack points to a virtual address with
859	    unpopulated page tables or arch code (switch_to() and switch_mm(),
860	    most likely) needs to ensure that the stack's page table entries
861	    are populated before running on a possibly unpopulated stack.
862
863	  - If the stack overflows into a guard page, something reasonable
864	    should happen.  The definition of "reasonable" is flexible, but
865	    instantly rebooting without logging anything would be unfriendly.
866
867config VMAP_STACK
868	default y
869	bool "Use a virtually-mapped stack"
870	depends on HAVE_ARCH_VMAP_STACK
871	depends on !KASAN || KASAN_VMALLOC
872	help
873	  Enable this if you want the use virtually-mapped kernel stacks
874	  with guard pages.  This causes kernel stack overflows to be
875	  caught immediately rather than causing difficult-to-diagnose
876	  corruption.
877
878	  To use this with KASAN, the architecture must support backing
879	  virtual mappings with real shadow memory, and KASAN_VMALLOC must
880	  be enabled.
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
881
882config ARCH_OPTIONAL_KERNEL_RWX
883	def_bool n
884
885config ARCH_OPTIONAL_KERNEL_RWX_DEFAULT
886	def_bool n
887
888config ARCH_HAS_STRICT_KERNEL_RWX
889	def_bool n
890
891config STRICT_KERNEL_RWX
892	bool "Make kernel text and rodata read-only" if ARCH_OPTIONAL_KERNEL_RWX
893	depends on ARCH_HAS_STRICT_KERNEL_RWX
894	default !ARCH_OPTIONAL_KERNEL_RWX || ARCH_OPTIONAL_KERNEL_RWX_DEFAULT
895	help
896	  If this is set, kernel text and rodata memory will be made read-only,
897	  and non-text memory will be made non-executable. This provides
898	  protection against certain security exploits (e.g. executing the heap
899	  or modifying text)
900
901	  These features are considered standard security practice these days.
902	  You should say Y here in almost all cases.
903
904config ARCH_HAS_STRICT_MODULE_RWX
905	def_bool n
906
907config STRICT_MODULE_RWX
908	bool "Set loadable kernel module data as NX and text as RO" if ARCH_OPTIONAL_KERNEL_RWX
909	depends on ARCH_HAS_STRICT_MODULE_RWX && MODULES
910	default !ARCH_OPTIONAL_KERNEL_RWX || ARCH_OPTIONAL_KERNEL_RWX_DEFAULT
911	help
912	  If this is set, module text and rodata memory will be made read-only,
913	  and non-text memory will be made non-executable. This provides
914	  protection against certain security exploits (e.g. writing to text)
915
916# select if the architecture provides an asm/dma-direct.h header
917config ARCH_HAS_PHYS_TO_DMA
918	bool
919
920config HAVE_ARCH_COMPILER_H
921	bool
922	help
923	  An architecture can select this if it provides an
924	  asm/compiler.h header that should be included after
925	  linux/compiler-*.h in order to override macro definitions that those
926	  headers generally provide.
927
928config HAVE_ARCH_PREL32_RELOCATIONS
929	bool
930	help
931	  May be selected by an architecture if it supports place-relative
932	  32-bit relocations, both in the toolchain and in the module loader,
933	  in which case relative references can be used in special sections
934	  for PCI fixup, initcalls etc which are only half the size on 64 bit
935	  architectures, and don't require runtime relocation on relocatable
936	  kernels.
937
938config ARCH_USE_MEMREMAP_PROT
939	bool
940
941config LOCK_EVENT_COUNTS
942	bool "Locking event counts collection"
943	depends on DEBUG_FS
944	help
945	  Enable light-weight counting of various locking related events
946	  in the system with minimal performance impact. This reduces
947	  the chance of application behavior change because of timing
948	  differences. The counts are reported via debugfs.
949
950# Select if the architecture has support for applying RELR relocations.
951config ARCH_HAS_RELR
952	bool
953
954config RELR
955	bool "Use RELR relocation packing"
956	depends on ARCH_HAS_RELR && TOOLS_SUPPORT_RELR
957	default y
958	help
959	  Store the kernel's dynamic relocations in the RELR relocation packing
960	  format. Requires a compatible linker (LLD supports this feature), as
961	  well as compatible NM and OBJCOPY utilities (llvm-nm and llvm-objcopy
962	  are compatible).
963
964config ARCH_HAS_MEM_ENCRYPT
965	bool
966
 
 
 
967config HAVE_SPARSE_SYSCALL_NR
968       bool
969       help
970          An architecture should select this if its syscall numbering is sparse
971	  to save space. For example, MIPS architecture has a syscall array with
972	  entries at 4000, 5000 and 6000 locations. This option turns on syscall
973	  related optimizations for a given architecture.
974
975config ARCH_HAS_VDSO_DATA
976	bool
977
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
978source "kernel/gcov/Kconfig"
979
980source "scripts/gcc-plugins/Kconfig"
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
981
982endmenu

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