1 # SPDX-License-Identifier: GPL-2.0
3 # General architecture dependent options
7 # Note: arch/$(SRCARCH)/Kconfig needs to be included first so that it can
8 # override the default values in this file.
10 source "arch/$(SRCARCH)/Kconfig"
12 menu "General architecture-dependent options"
31 tristate "OProfile system profiling"
33 depends on HAVE_OPROFILE
35 select RING_BUFFER_ALLOW_SWAP
37 OProfile is a profiling system capable of profiling the
38 whole system, include the kernel, kernel modules, libraries,
43 config OPROFILE_EVENT_MULTIPLEX
44 bool "OProfile multiplexing support (EXPERIMENTAL)"
46 depends on OPROFILE && X86
48 The number of hardware counters is limited. The multiplexing
49 feature enables OProfile to gather more events than counters
50 are provided by the hardware. This is realized by switching
51 between events at a user specified time interval.
58 config OPROFILE_NMI_TIMER
60 depends on PERF_EVENTS && HAVE_PERF_EVENTS_NMI && !PPC64
65 depends on HAVE_KPROBES
68 Kprobes allows you to trap at almost any kernel address and
69 execute a callback function. register_kprobe() establishes
70 a probepoint and specifies the callback. Kprobes is useful
71 for kernel debugging, non-intrusive instrumentation and testing.
75 bool "Optimize very unlikely/likely branches"
76 depends on HAVE_ARCH_JUMP_LABEL
77 depends on CC_HAS_ASM_GOTO
79 This option enables a transparent branch optimization that
80 makes certain almost-always-true or almost-always-false branch
81 conditions even cheaper to execute within the kernel.
83 Certain performance-sensitive kernel code, such as trace points,
84 scheduler functionality, networking code and KVM have such
85 branches and include support for this optimization technique.
87 If it is detected that the compiler has support for "asm goto",
88 the kernel will compile such branches with just a nop
89 instruction. When the condition flag is toggled to true, the
90 nop will be converted to a jump instruction to execute the
91 conditional block of instructions.
93 This technique lowers overhead and stress on the branch prediction
94 of the processor and generally makes the kernel faster. The update
95 of the condition is slower, but those are always very rare.
97 ( On 32-bit x86, the necessary options added to the compiler
98 flags may increase the size of the kernel slightly. )
100 config STATIC_KEYS_SELFTEST
101 bool "Static key selftest"
102 depends on JUMP_LABEL
104 Boot time self-test of the branch patching code.
108 depends on KPROBES && HAVE_OPTPROBES
109 select TASKS_RCU if PREEMPTION
111 config KPROBES_ON_FTRACE
113 depends on KPROBES && HAVE_KPROBES_ON_FTRACE
114 depends on DYNAMIC_FTRACE_WITH_REGS
116 If function tracer is enabled and the arch supports full
117 passing of pt_regs to function tracing, then kprobes can
118 optimize on top of function tracing.
122 depends on ARCH_SUPPORTS_UPROBES
124 Uprobes is the user-space counterpart to kprobes: they
125 enable instrumentation applications (such as 'perf probe')
126 to establish unintrusive probes in user-space binaries and
127 libraries, by executing handler functions when the probes
128 are hit by user-space applications.
130 ( These probes come in the form of single-byte breakpoints,
131 managed by the kernel and kept transparent to the probed
134 config HAVE_64BIT_ALIGNED_ACCESS
135 def_bool 64BIT && !HAVE_EFFICIENT_UNALIGNED_ACCESS
137 Some architectures require 64 bit accesses to be 64 bit
138 aligned, which also requires structs containing 64 bit values
139 to be 64 bit aligned too. This includes some 32 bit
140 architectures which can do 64 bit accesses, as well as 64 bit
141 architectures without unaligned access.
143 This symbol should be selected by an architecture if 64 bit
144 accesses are required to be 64 bit aligned in this way even
145 though it is not a 64 bit architecture.
147 See Documentation/unaligned-memory-access.txt for more
148 information on the topic of unaligned memory accesses.
150 config HAVE_EFFICIENT_UNALIGNED_ACCESS
153 Some architectures are unable to perform unaligned accesses
154 without the use of get_unaligned/put_unaligned. Others are
155 unable to perform such accesses efficiently (e.g. trap on
156 unaligned access and require fixing it up in the exception
159 This symbol should be selected by an architecture if it can
160 perform unaligned accesses efficiently to allow different
161 code paths to be selected for these cases. Some network
162 drivers, for example, could opt to not fix up alignment
163 problems with received packets if doing so would not help
166 See Documentation/unaligned-memory-access.txt for more
167 information on the topic of unaligned memory accesses.
169 config ARCH_USE_BUILTIN_BSWAP
172 Modern versions of GCC (since 4.4) have builtin functions
173 for handling byte-swapping. Using these, instead of the old
174 inline assembler that the architecture code provides in the
175 __arch_bswapXX() macros, allows the compiler to see what's
176 happening and offers more opportunity for optimisation. In
177 particular, the compiler will be able to combine the byteswap
178 with a nearby load or store and use load-and-swap or
179 store-and-swap instructions if the architecture has them. It
180 should almost *never* result in code which is worse than the
181 hand-coded assembler in <asm/swab.h>. But just in case it
182 does, the use of the builtins is optional.
184 Any architecture with load-and-swap or store-and-swap
185 instructions should set this. And it shouldn't hurt to set it
186 on architectures that don't have such instructions.
190 depends on KPROBES && HAVE_KRETPROBES
192 config USER_RETURN_NOTIFIER
194 depends on HAVE_USER_RETURN_NOTIFIER
196 Provide a kernel-internal notification when a cpu is about to
199 config HAVE_IOREMAP_PROT
205 config HAVE_KRETPROBES
208 config HAVE_OPTPROBES
211 config HAVE_KPROBES_ON_FTRACE
214 config HAVE_FUNCTION_ERROR_INJECTION
221 # An arch should select this if it provides all these things:
223 # task_pt_regs() in asm/processor.h or asm/ptrace.h
224 # arch_has_single_step() if there is hardware single-step support
225 # arch_has_block_step() if there is hardware block-step support
226 # asm/syscall.h supplying asm-generic/syscall.h interface
227 # linux/regset.h user_regset interfaces
228 # CORE_DUMP_USE_REGSET #define'd in linux/elf.h
229 # TIF_SYSCALL_TRACE calls tracehook_report_syscall_{entry,exit}
230 # TIF_NOTIFY_RESUME calls tracehook_notify_resume()
231 # signal delivery calls tracehook_signal_handler()
233 config HAVE_ARCH_TRACEHOOK
236 config HAVE_DMA_CONTIGUOUS
239 config GENERIC_SMP_IDLE_THREAD
242 config GENERIC_IDLE_POLL_SETUP
245 config ARCH_HAS_FORTIFY_SOURCE
248 An architecture should select this when it can successfully
249 build and run with CONFIG_FORTIFY_SOURCE.
252 # Select if the arch provides a historic keepinit alias for the retain_initrd
253 # command line option
255 config ARCH_HAS_KEEPINITRD
258 # Select if arch has all set_memory_ro/rw/x/nx() functions in asm/cacheflush.h
259 config ARCH_HAS_SET_MEMORY
262 # Select if arch has all set_direct_map_invalid/default() functions
263 config ARCH_HAS_SET_DIRECT_MAP
267 # Select if arch has an uncached kernel segment and provides the
268 # uncached_kernel_address / cached_kernel_address symbols to use it
270 config ARCH_HAS_UNCACHED_SEGMENT
271 select ARCH_HAS_DMA_PREP_COHERENT
274 config ARCH_HAS_CPU_FINALIZE_INIT
277 # Select if arch init_task must go in the __init_task_data section
278 config ARCH_TASK_STRUCT_ON_STACK
281 # Select if arch has its private alloc_task_struct() function
282 config ARCH_TASK_STRUCT_ALLOCATOR
285 config HAVE_ARCH_THREAD_STRUCT_WHITELIST
287 depends on !ARCH_TASK_STRUCT_ALLOCATOR
289 An architecture should select this to provide hardened usercopy
290 knowledge about what region of the thread_struct should be
291 whitelisted for copying to userspace. Normally this is only the
292 FPU registers. Specifically, arch_thread_struct_whitelist()
293 should be implemented. Without this, the entire thread_struct
294 field in task_struct will be left whitelisted.
296 # Select if arch has its private alloc_thread_stack() function
297 config ARCH_THREAD_STACK_ALLOCATOR
300 # Select if arch wants to size task_struct dynamically via arch_task_struct_size:
301 config ARCH_WANTS_DYNAMIC_TASK_STRUCT
304 config ARCH_32BIT_OFF_T
308 All new 32-bit architectures should have 64-bit off_t type on
309 userspace side which corresponds to the loff_t kernel type. This
310 is the requirement for modern ABIs. Some existing architectures
311 still support 32-bit off_t. This option is enabled for all such
312 architectures explicitly.
314 config HAVE_ASM_MODVERSIONS
317 This symbol should be selected by an architecure if it provides
318 <asm/asm-prototypes.h> to support the module versioning for symbols
319 exported from assembly code.
321 config HAVE_REGS_AND_STACK_ACCESS_API
324 This symbol should be selected by an architecure if it supports
325 the API needed to access registers and stack entries from pt_regs,
326 declared in asm/ptrace.h
327 For example the kprobes-based event tracer needs this API.
331 depends on HAVE_REGS_AND_STACK_ACCESS_API
333 This symbol should be selected by an architecture if it
334 supports an implementation of restartable sequences.
336 config HAVE_FUNCTION_ARG_ACCESS_API
339 This symbol should be selected by an architecure if it supports
340 the API needed to access function arguments from pt_regs,
341 declared in asm/ptrace.h
346 The <linux/clk.h> calls support software clock gating and
347 thus are a key power management tool on many systems.
349 config HAVE_HW_BREAKPOINT
351 depends on PERF_EVENTS
353 config HAVE_MIXED_BREAKPOINTS_REGS
355 depends on HAVE_HW_BREAKPOINT
357 Depending on the arch implementation of hardware breakpoints,
358 some of them have separate registers for data and instruction
359 breakpoints addresses, others have mixed registers to store
360 them but define the access type in a control register.
361 Select this option if your arch implements breakpoints under the
364 config HAVE_USER_RETURN_NOTIFIER
367 config HAVE_PERF_EVENTS_NMI
370 System hardware can generate an NMI using the perf event
371 subsystem. Also has support for calculating CPU cycle events
372 to determine how many clock cycles in a given period.
374 config HAVE_HARDLOCKUP_DETECTOR_PERF
376 depends on HAVE_PERF_EVENTS_NMI
378 The arch chooses to use the generic perf-NMI-based hardlockup
379 detector. Must define HAVE_PERF_EVENTS_NMI.
381 config HAVE_NMI_WATCHDOG
385 The arch provides a low level NMI watchdog. It provides
386 asm/nmi.h, and defines its own arch_touch_nmi_watchdog().
388 config HAVE_HARDLOCKUP_DETECTOR_ARCH
390 select HAVE_NMI_WATCHDOG
392 The arch chooses to provide its own hardlockup detector, which is
393 a superset of the HAVE_NMI_WATCHDOG. It also conforms to config
394 interfaces and parameters provided by hardlockup detector subsystem.
396 config HAVE_PERF_REGS
399 Support selective register dumps for perf events. This includes
400 bit-mapping of each registers and a unique architecture id.
402 config HAVE_PERF_USER_STACK_DUMP
405 Support user stack dumps for perf event samples. This needs
406 access to the user stack pointer which is not unified across
409 config HAVE_ARCH_JUMP_LABEL
412 config HAVE_ARCH_JUMP_LABEL_RELATIVE
415 config HAVE_RCU_TABLE_FREE
418 config HAVE_MMU_GATHER_PAGE_SIZE
421 config MMU_GATHER_NO_RANGE
424 config HAVE_MMU_GATHER_NO_GATHER
427 config ARCH_WANT_IRQS_OFF_ACTIVATE_MM
430 Temporary select until all architectures can be converted to have
431 irqs disabled over activate_mm. Architectures that do IPI based TLB
432 shootdowns should enable this.
434 config ARCH_HAVE_NMI_SAFE_CMPXCHG
437 config HAVE_ALIGNED_STRUCT_PAGE
440 This makes sure that struct pages are double word aligned and that
441 e.g. the SLUB allocator can perform double word atomic operations
442 on a struct page for better performance. However selecting this
443 might increase the size of a struct page by a word.
445 config HAVE_CMPXCHG_LOCAL
448 config HAVE_CMPXCHG_DOUBLE
451 config ARCH_WEAK_RELEASE_ACQUIRE
454 config ARCH_WANT_IPC_PARSE_VERSION
457 config ARCH_WANT_COMPAT_IPC_PARSE_VERSION
460 config ARCH_WANT_OLD_COMPAT_IPC
461 select ARCH_WANT_COMPAT_IPC_PARSE_VERSION
464 config HAVE_ARCH_SECCOMP_FILTER
467 An arch should select this symbol if it provides all of these things:
469 - syscall_get_arguments()
471 - syscall_set_return_value()
472 - SIGSYS siginfo_t support
473 - secure_computing is called from a ptrace_event()-safe context
474 - secure_computing return value is checked and a return value of -1
475 results in the system call being skipped immediately.
476 - seccomp syscall wired up
478 config SECCOMP_FILTER
480 depends on HAVE_ARCH_SECCOMP_FILTER && SECCOMP && NET
482 Enable tasks to build secure computing environments defined
483 in terms of Berkeley Packet Filter programs which implement
484 task-defined system call filtering polices.
486 See Documentation/userspace-api/seccomp_filter.rst for details.
488 config HAVE_ARCH_STACKLEAK
491 An architecture should select this if it has the code which
492 fills the used part of the kernel stack with the STACKLEAK_POISON
493 value before returning from system calls.
495 config HAVE_STACKPROTECTOR
498 An arch should select this symbol if:
499 - it has implemented a stack canary (e.g. __stack_chk_guard)
501 config CC_HAS_STACKPROTECTOR_NONE
502 def_bool $(cc-option,-fno-stack-protector)
504 config STACKPROTECTOR
505 bool "Stack Protector buffer overflow detection"
506 depends on HAVE_STACKPROTECTOR
507 depends on $(cc-option,-fstack-protector)
510 This option turns on the "stack-protector" GCC feature. This
511 feature puts, at the beginning of functions, a canary value on
512 the stack just before the return address, and validates
513 the value just before actually returning. Stack based buffer
514 overflows (that need to overwrite this return address) now also
515 overwrite the canary, which gets detected and the attack is then
516 neutralized via a kernel panic.
518 Functions will have the stack-protector canary logic added if they
519 have an 8-byte or larger character array on the stack.
521 This feature requires gcc version 4.2 or above, or a distribution
522 gcc with the feature backported ("-fstack-protector").
524 On an x86 "defconfig" build, this feature adds canary checks to
525 about 3% of all kernel functions, which increases kernel code size
528 config STACKPROTECTOR_STRONG
529 bool "Strong Stack Protector"
530 depends on STACKPROTECTOR
531 depends on $(cc-option,-fstack-protector-strong)
534 Functions will have the stack-protector canary logic added in any
535 of the following conditions:
537 - local variable's address used as part of the right hand side of an
538 assignment or function argument
539 - local variable is an array (or union containing an array),
540 regardless of array type or length
541 - uses register local variables
543 This feature requires gcc version 4.9 or above, or a distribution
544 gcc with the feature backported ("-fstack-protector-strong").
546 On an x86 "defconfig" build, this feature adds canary checks to
547 about 20% of all kernel functions, which increases the kernel code
550 config HAVE_ARCH_WITHIN_STACK_FRAMES
553 An architecture should select this if it can walk the kernel stack
554 frames to determine if an object is part of either the arguments
555 or local variables (i.e. that it excludes saved return addresses,
556 and similar) by implementing an inline arch_within_stack_frames(),
557 which is used by CONFIG_HARDENED_USERCOPY.
559 config HAVE_CONTEXT_TRACKING
562 Provide kernel/user boundaries probes necessary for subsystems
563 that need it, such as userspace RCU extended quiescent state.
564 Syscalls need to be wrapped inside user_exit()-user_enter() through
565 the slow path using TIF_NOHZ flag. Exceptions handlers must be
566 wrapped as well. Irqs are already protected inside
567 rcu_irq_enter/rcu_irq_exit() but preemption or signal handling on
568 irq exit still need to be protected.
570 config HAVE_VIRT_CPU_ACCOUNTING
573 config ARCH_HAS_SCALED_CPUTIME
576 config HAVE_VIRT_CPU_ACCOUNTING_GEN
580 With VIRT_CPU_ACCOUNTING_GEN, cputime_t becomes 64-bit.
581 Before enabling this option, arch code must be audited
582 to ensure there are no races in concurrent read/write of
583 cputime_t. For example, reading/writing 64-bit cputime_t on
584 some 32-bit arches may require multiple accesses, so proper
585 locking is needed to protect against concurrent accesses.
588 config HAVE_IRQ_TIME_ACCOUNTING
591 Archs need to ensure they use a high enough resolution clock to
592 support irq time accounting and then call enable_sched_clock_irqtime().
597 Archs that select this are able to move page tables at the PMD level.
599 config HAVE_ARCH_TRANSPARENT_HUGEPAGE
602 config HAVE_ARCH_TRANSPARENT_HUGEPAGE_PUD
605 config HAVE_ARCH_HUGE_VMAP
608 config ARCH_WANT_HUGE_PMD_SHARE
611 config HAVE_ARCH_SOFT_DIRTY
614 config HAVE_MOD_ARCH_SPECIFIC
617 The arch uses struct mod_arch_specific to store data. Many arches
618 just need a simple module loader without arch specific data - those
619 should not enable this.
621 config MODULES_USE_ELF_RELA
624 Modules only use ELF RELA relocations. Modules with ELF REL
625 relocations will give an error.
627 config MODULES_USE_ELF_REL
630 Modules only use ELF REL relocations. Modules with ELF RELA
631 relocations will give an error.
633 config HAVE_IRQ_EXIT_ON_IRQ_STACK
636 Architecture doesn't only execute the irq handler on the irq stack
637 but also irq_exit(). This way we can process softirqs on this irq
638 stack instead of switching to a new one when we call __do_softirq()
639 in the end of an hardirq.
640 This spares a stack switch and improves cache usage on softirq
643 config PGTABLE_LEVELS
647 config ARCH_HAS_ELF_RANDOMIZE
650 An architecture supports choosing randomized locations for
651 stack, mmap, brk, and ET_DYN. Defined functions:
653 - arch_randomize_brk()
655 config HAVE_ARCH_MMAP_RND_BITS
658 An arch should select this symbol if it supports setting a variable
659 number of bits for use in establishing the base address for mmap
660 allocations, has MMU enabled and provides values for both:
661 - ARCH_MMAP_RND_BITS_MIN
662 - ARCH_MMAP_RND_BITS_MAX
664 config HAVE_EXIT_THREAD
667 An architecture implements exit_thread.
669 config ARCH_MMAP_RND_BITS_MIN
672 config ARCH_MMAP_RND_BITS_MAX
675 config ARCH_MMAP_RND_BITS_DEFAULT
678 config ARCH_MMAP_RND_BITS
679 int "Number of bits to use for ASLR of mmap base address" if EXPERT
680 range ARCH_MMAP_RND_BITS_MIN ARCH_MMAP_RND_BITS_MAX
681 default ARCH_MMAP_RND_BITS_DEFAULT if ARCH_MMAP_RND_BITS_DEFAULT
682 default ARCH_MMAP_RND_BITS_MIN
683 depends on HAVE_ARCH_MMAP_RND_BITS
685 This value can be used to select the number of bits to use to
686 determine the random offset to the base address of vma regions
687 resulting from mmap allocations. This value will be bounded
688 by the architecture's minimum and maximum supported values.
690 This value can be changed after boot using the
691 /proc/sys/vm/mmap_rnd_bits tunable
693 config HAVE_ARCH_MMAP_RND_COMPAT_BITS
696 An arch should select this symbol if it supports running applications
697 in compatibility mode, supports setting a variable number of bits for
698 use in establishing the base address for mmap allocations, has MMU
699 enabled and provides values for both:
700 - ARCH_MMAP_RND_COMPAT_BITS_MIN
701 - ARCH_MMAP_RND_COMPAT_BITS_MAX
703 config ARCH_MMAP_RND_COMPAT_BITS_MIN
706 config ARCH_MMAP_RND_COMPAT_BITS_MAX
709 config ARCH_MMAP_RND_COMPAT_BITS_DEFAULT
712 config ARCH_MMAP_RND_COMPAT_BITS
713 int "Number of bits to use for ASLR of mmap base address for compatible applications" if EXPERT
714 range ARCH_MMAP_RND_COMPAT_BITS_MIN ARCH_MMAP_RND_COMPAT_BITS_MAX
715 default ARCH_MMAP_RND_COMPAT_BITS_DEFAULT if ARCH_MMAP_RND_COMPAT_BITS_DEFAULT
716 default ARCH_MMAP_RND_COMPAT_BITS_MIN
717 depends on HAVE_ARCH_MMAP_RND_COMPAT_BITS
719 This value can be used to select the number of bits to use to
720 determine the random offset to the base address of vma regions
721 resulting from mmap allocations for compatible applications This
722 value will be bounded by the architecture's minimum and maximum
725 This value can be changed after boot using the
726 /proc/sys/vm/mmap_rnd_compat_bits tunable
728 config HAVE_ARCH_COMPAT_MMAP_BASES
731 This allows 64bit applications to invoke 32-bit mmap() syscall
732 and vice-versa 32-bit applications to call 64-bit mmap().
733 Required for applications doing different bitness syscalls.
735 # This allows to use a set of generic functions to determine mmap base
736 # address by giving priority to top-down scheme only if the process
737 # is not in legacy mode (compat task, unlimited stack size or
738 # sysctl_legacy_va_layout).
739 # Architecture that selects this option can provide its own version of:
741 config ARCH_WANT_DEFAULT_TOPDOWN_MMAP_LAYOUT
744 select ARCH_HAS_ELF_RANDOMIZE
746 config HAVE_COPY_THREAD_TLS
749 Architecture provides copy_thread_tls to accept tls argument via
750 normal C parameter passing, rather than extracting the syscall
751 argument from pt_regs.
753 config HAVE_STACK_VALIDATION
756 Architecture supports the 'objtool check' host tool command, which
757 performs compile-time stack metadata validation.
759 config HAVE_RELIABLE_STACKTRACE
762 Architecture has a save_stack_trace_tsk_reliable() function which
763 only returns a stack trace if it can guarantee the trace is reliable.
765 config HAVE_ARCH_HASH
769 If this is set, the architecture provides an <asm/hash.h>
770 file which provides platform-specific implementations of some
771 functions in <linux/hash.h> or fs/namei.c.
773 config HAVE_ARCH_NVRAM_OPS
782 config CLONE_BACKWARDS
785 Architecture has tls passed as the 4th argument of clone(2),
788 config CLONE_BACKWARDS2
791 Architecture has the first two arguments of clone(2) swapped.
793 config CLONE_BACKWARDS3
796 Architecture has tls passed as the 3rd argument of clone(2),
799 config ODD_RT_SIGACTION
802 Architecture has unusual rt_sigaction(2) arguments
804 config OLD_SIGSUSPEND
807 Architecture has old sigsuspend(2) syscall, of one-argument variety
809 config OLD_SIGSUSPEND3
812 Even weirder antique ABI - three-argument sigsuspend(2)
817 Architecture has old sigaction(2) syscall. Nope, not the same
818 as OLD_SIGSUSPEND | OLD_SIGSUSPEND3 - alpha has sigsuspend(2),
819 but fairly different variant of sigaction(2), thanks to OSF/1
822 config COMPAT_OLD_SIGACTION
828 This should be selected by all architectures that need to support
829 new system calls with a 64-bit time_t. This is relevant on all 32-bit
830 architectures, and 64-bit architectures as part of compat syscall
833 config COMPAT_32BIT_TIME
834 def_bool !64BIT || COMPAT
836 This enables 32 bit time_t support in addition to 64 bit time_t support.
837 This is relevant on all 32-bit architectures, and 64-bit architectures
838 as part of compat syscall handling.
840 config ARCH_NO_PREEMPT
843 config ARCH_SUPPORTS_RT
846 config CPU_NO_EFFICIENT_FFS
849 config HAVE_ARCH_VMAP_STACK
852 An arch should select this symbol if it can support kernel stacks
853 in vmalloc space. This means:
855 - vmalloc space must be large enough to hold many kernel stacks.
856 This may rule out many 32-bit architectures.
858 - Stacks in vmalloc space need to work reliably. For example, if
859 vmap page tables are created on demand, either this mechanism
860 needs to work while the stack points to a virtual address with
861 unpopulated page tables or arch code (switch_to() and switch_mm(),
862 most likely) needs to ensure that the stack's page table entries
863 are populated before running on a possibly unpopulated stack.
865 - If the stack overflows into a guard page, something reasonable
866 should happen. The definition of "reasonable" is flexible, but
867 instantly rebooting without logging anything would be unfriendly.
871 bool "Use a virtually-mapped stack"
872 depends on HAVE_ARCH_VMAP_STACK && !KASAN
874 Enable this if you want the use virtually-mapped kernel stacks
875 with guard pages. This causes kernel stack overflows to be
876 caught immediately rather than causing difficult-to-diagnose
879 This is presently incompatible with KASAN because KASAN expects
880 the stack to map directly to the KASAN shadow map using a formula
881 that is incorrect if the stack is in vmalloc space.
883 config ARCH_OPTIONAL_KERNEL_RWX
886 config ARCH_OPTIONAL_KERNEL_RWX_DEFAULT
889 config ARCH_HAS_STRICT_KERNEL_RWX
892 config STRICT_KERNEL_RWX
893 bool "Make kernel text and rodata read-only" if ARCH_OPTIONAL_KERNEL_RWX
894 depends on ARCH_HAS_STRICT_KERNEL_RWX
895 default !ARCH_OPTIONAL_KERNEL_RWX || ARCH_OPTIONAL_KERNEL_RWX_DEFAULT
897 If this is set, kernel text and rodata memory will be made read-only,
898 and non-text memory will be made non-executable. This provides
899 protection against certain security exploits (e.g. executing the heap
902 These features are considered standard security practice these days.
903 You should say Y here in almost all cases.
905 config ARCH_HAS_STRICT_MODULE_RWX
908 config STRICT_MODULE_RWX
909 bool "Set loadable kernel module data as NX and text as RO" if ARCH_OPTIONAL_KERNEL_RWX
910 depends on ARCH_HAS_STRICT_MODULE_RWX && MODULES
911 default !ARCH_OPTIONAL_KERNEL_RWX || ARCH_OPTIONAL_KERNEL_RWX_DEFAULT
913 If this is set, module text and rodata memory will be made read-only,
914 and non-text memory will be made non-executable. This provides
915 protection against certain security exploits (e.g. writing to text)
917 # select if the architecture provides an asm/dma-direct.h header
918 config ARCH_HAS_PHYS_TO_DMA
921 config HAVE_ARCH_COMPILER_H
924 An architecture can select this if it provides an
925 asm/compiler.h header that should be included after
926 linux/compiler-*.h in order to override macro definitions that those
927 headers generally provide.
929 config HAVE_ARCH_PREL32_RELOCATIONS
932 May be selected by an architecture if it supports place-relative
933 32-bit relocations, both in the toolchain and in the module loader,
934 in which case relative references can be used in special sections
935 for PCI fixup, initcalls etc which are only half the size on 64 bit
936 architectures, and don't require runtime relocation on relocatable
939 config ARCH_USE_MEMREMAP_PROT
942 config LOCK_EVENT_COUNTS
943 bool "Locking event counts collection"
946 Enable light-weight counting of various locking related events
947 in the system with minimal performance impact. This reduces
948 the chance of application behavior change because of timing
949 differences. The counts are reported via debugfs.
951 # Select if the architecture has support for applying RELR relocations.
956 bool "Use RELR relocation packing"
957 depends on ARCH_HAS_RELR && TOOLS_SUPPORT_RELR
960 Store the kernel's dynamic relocations in the RELR relocation packing
961 format. Requires a compatible linker (LLD supports this feature), as
962 well as compatible NM and OBJCOPY utilities (llvm-nm and llvm-objcopy
965 config ARCH_HAS_MEM_ENCRYPT
968 source "kernel/gcov/Kconfig"
970 source "scripts/gcc-plugins/Kconfig"