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_EFFICIENT_UNALIGNED_ACCESS
137 Some architectures are unable to perform unaligned accesses
138 without the use of get_unaligned/put_unaligned. Others are
139 unable to perform such accesses efficiently (e.g. trap on
140 unaligned access and require fixing it up in the exception
143 This symbol should be selected by an architecture if it can
144 perform unaligned accesses efficiently to allow different
145 code paths to be selected for these cases. Some network
146 drivers, for example, could opt to not fix up alignment
147 problems with received packets if doing so would not help
150 See Documentation/unaligned-memory-access.txt for more
151 information on the topic of unaligned memory accesses.
153 config ARCH_USE_BUILTIN_BSWAP
156 Modern versions of GCC (since 4.4) have builtin functions
157 for handling byte-swapping. Using these, instead of the old
158 inline assembler that the architecture code provides in the
159 __arch_bswapXX() macros, allows the compiler to see what's
160 happening and offers more opportunity for optimisation. In
161 particular, the compiler will be able to combine the byteswap
162 with a nearby load or store and use load-and-swap or
163 store-and-swap instructions if the architecture has them. It
164 should almost *never* result in code which is worse than the
165 hand-coded assembler in <asm/swab.h>. But just in case it
166 does, the use of the builtins is optional.
168 Any architecture with load-and-swap or store-and-swap
169 instructions should set this. And it shouldn't hurt to set it
170 on architectures that don't have such instructions.
174 depends on KPROBES && HAVE_KRETPROBES
176 config USER_RETURN_NOTIFIER
178 depends on HAVE_USER_RETURN_NOTIFIER
180 Provide a kernel-internal notification when a cpu is about to
183 config HAVE_IOREMAP_PROT
189 config HAVE_KRETPROBES
192 config HAVE_OPTPROBES
195 config HAVE_KPROBES_ON_FTRACE
198 config HAVE_FUNCTION_ERROR_INJECTION
205 # An arch should select this if it provides all these things:
207 # task_pt_regs() in asm/processor.h or asm/ptrace.h
208 # arch_has_single_step() if there is hardware single-step support
209 # arch_has_block_step() if there is hardware block-step support
210 # asm/syscall.h supplying asm-generic/syscall.h interface
211 # linux/regset.h user_regset interfaces
212 # CORE_DUMP_USE_REGSET #define'd in linux/elf.h
213 # TIF_SYSCALL_TRACE calls tracehook_report_syscall_{entry,exit}
214 # TIF_NOTIFY_RESUME calls tracehook_notify_resume()
215 # signal delivery calls tracehook_signal_handler()
217 config HAVE_ARCH_TRACEHOOK
220 config HAVE_DMA_CONTIGUOUS
223 config GENERIC_SMP_IDLE_THREAD
226 config GENERIC_IDLE_POLL_SETUP
229 config ARCH_HAS_FORTIFY_SOURCE
232 An architecture should select this when it can successfully
233 build and run with CONFIG_FORTIFY_SOURCE.
236 # Select if the arch provides a historic keepinit alias for the retain_initrd
237 # command line option
239 config ARCH_HAS_KEEPINITRD
242 # Select if arch has all set_memory_ro/rw/x/nx() functions in asm/cacheflush.h
243 config ARCH_HAS_SET_MEMORY
246 # Select if arch has all set_direct_map_invalid/default() functions
247 config ARCH_HAS_SET_DIRECT_MAP
251 # Select if arch has an uncached kernel segment and provides the
252 # uncached_kernel_address / cached_kernel_address symbols to use it
254 config ARCH_HAS_UNCACHED_SEGMENT
255 select ARCH_HAS_DMA_PREP_COHERENT
258 # Select if arch init_task must go in the __init_task_data section
259 config ARCH_TASK_STRUCT_ON_STACK
262 # Select if arch has its private alloc_task_struct() function
263 config ARCH_TASK_STRUCT_ALLOCATOR
266 config HAVE_ARCH_THREAD_STRUCT_WHITELIST
268 depends on !ARCH_TASK_STRUCT_ALLOCATOR
270 An architecture should select this to provide hardened usercopy
271 knowledge about what region of the thread_struct should be
272 whitelisted for copying to userspace. Normally this is only the
273 FPU registers. Specifically, arch_thread_struct_whitelist()
274 should be implemented. Without this, the entire thread_struct
275 field in task_struct will be left whitelisted.
277 # Select if arch has its private alloc_thread_stack() function
278 config ARCH_THREAD_STACK_ALLOCATOR
281 # Select if arch wants to size task_struct dynamically via arch_task_struct_size:
282 config ARCH_WANTS_DYNAMIC_TASK_STRUCT
285 config ARCH_32BIT_OFF_T
289 All new 32-bit architectures should have 64-bit off_t type on
290 userspace side which corresponds to the loff_t kernel type. This
291 is the requirement for modern ABIs. Some existing architectures
292 still support 32-bit off_t. This option is enabled for all such
293 architectures explicitly.
295 config HAVE_REGS_AND_STACK_ACCESS_API
298 This symbol should be selected by an architecure if it supports
299 the API needed to access registers and stack entries from pt_regs,
300 declared in asm/ptrace.h
301 For example the kprobes-based event tracer needs this API.
305 depends on HAVE_REGS_AND_STACK_ACCESS_API
307 This symbol should be selected by an architecture if it
308 supports an implementation of restartable sequences.
310 config HAVE_FUNCTION_ARG_ACCESS_API
313 This symbol should be selected by an architecure if it supports
314 the API needed to access function arguments from pt_regs,
315 declared in asm/ptrace.h
320 The <linux/clk.h> calls support software clock gating and
321 thus are a key power management tool on many systems.
323 config HAVE_HW_BREAKPOINT
325 depends on PERF_EVENTS
327 config HAVE_MIXED_BREAKPOINTS_REGS
329 depends on HAVE_HW_BREAKPOINT
331 Depending on the arch implementation of hardware breakpoints,
332 some of them have separate registers for data and instruction
333 breakpoints addresses, others have mixed registers to store
334 them but define the access type in a control register.
335 Select this option if your arch implements breakpoints under the
338 config HAVE_USER_RETURN_NOTIFIER
341 config HAVE_PERF_EVENTS_NMI
344 System hardware can generate an NMI using the perf event
345 subsystem. Also has support for calculating CPU cycle events
346 to determine how many clock cycles in a given period.
348 config HAVE_HARDLOCKUP_DETECTOR_PERF
350 depends on HAVE_PERF_EVENTS_NMI
352 The arch chooses to use the generic perf-NMI-based hardlockup
353 detector. Must define HAVE_PERF_EVENTS_NMI.
355 config HAVE_NMI_WATCHDOG
359 The arch provides a low level NMI watchdog. It provides
360 asm/nmi.h, and defines its own arch_touch_nmi_watchdog().
362 config HAVE_HARDLOCKUP_DETECTOR_ARCH
364 select HAVE_NMI_WATCHDOG
366 The arch chooses to provide its own hardlockup detector, which is
367 a superset of the HAVE_NMI_WATCHDOG. It also conforms to config
368 interfaces and parameters provided by hardlockup detector subsystem.
370 config HAVE_PERF_REGS
373 Support selective register dumps for perf events. This includes
374 bit-mapping of each registers and a unique architecture id.
376 config HAVE_PERF_USER_STACK_DUMP
379 Support user stack dumps for perf event samples. This needs
380 access to the user stack pointer which is not unified across
383 config HAVE_ARCH_JUMP_LABEL
386 config HAVE_ARCH_JUMP_LABEL_RELATIVE
389 config HAVE_RCU_TABLE_FREE
392 config HAVE_RCU_TABLE_NO_INVALIDATE
395 config HAVE_MMU_GATHER_PAGE_SIZE
398 config HAVE_MMU_GATHER_NO_GATHER
401 config ARCH_HAVE_NMI_SAFE_CMPXCHG
404 config HAVE_ALIGNED_STRUCT_PAGE
407 This makes sure that struct pages are double word aligned and that
408 e.g. the SLUB allocator can perform double word atomic operations
409 on a struct page for better performance. However selecting this
410 might increase the size of a struct page by a word.
412 config HAVE_CMPXCHG_LOCAL
415 config HAVE_CMPXCHG_DOUBLE
418 config ARCH_WEAK_RELEASE_ACQUIRE
421 config ARCH_WANT_IPC_PARSE_VERSION
424 config ARCH_WANT_COMPAT_IPC_PARSE_VERSION
427 config ARCH_WANT_OLD_COMPAT_IPC
428 select ARCH_WANT_COMPAT_IPC_PARSE_VERSION
431 config HAVE_ARCH_SECCOMP_FILTER
434 An arch should select this symbol if it provides all of these things:
436 - syscall_get_arguments()
438 - syscall_set_return_value()
439 - SIGSYS siginfo_t support
440 - secure_computing is called from a ptrace_event()-safe context
441 - secure_computing return value is checked and a return value of -1
442 results in the system call being skipped immediately.
443 - seccomp syscall wired up
445 config SECCOMP_FILTER
447 depends on HAVE_ARCH_SECCOMP_FILTER && SECCOMP && NET
449 Enable tasks to build secure computing environments defined
450 in terms of Berkeley Packet Filter programs which implement
451 task-defined system call filtering polices.
453 See Documentation/userspace-api/seccomp_filter.rst for details.
455 config HAVE_ARCH_STACKLEAK
458 An architecture should select this if it has the code which
459 fills the used part of the kernel stack with the STACKLEAK_POISON
460 value before returning from system calls.
462 config HAVE_STACKPROTECTOR
465 An arch should select this symbol if:
466 - it has implemented a stack canary (e.g. __stack_chk_guard)
468 config CC_HAS_STACKPROTECTOR_NONE
469 def_bool $(cc-option,-fno-stack-protector)
471 config STACKPROTECTOR
472 bool "Stack Protector buffer overflow detection"
473 depends on HAVE_STACKPROTECTOR
474 depends on $(cc-option,-fstack-protector)
477 This option turns on the "stack-protector" GCC feature. This
478 feature puts, at the beginning of functions, a canary value on
479 the stack just before the return address, and validates
480 the value just before actually returning. Stack based buffer
481 overflows (that need to overwrite this return address) now also
482 overwrite the canary, which gets detected and the attack is then
483 neutralized via a kernel panic.
485 Functions will have the stack-protector canary logic added if they
486 have an 8-byte or larger character array on the stack.
488 This feature requires gcc version 4.2 or above, or a distribution
489 gcc with the feature backported ("-fstack-protector").
491 On an x86 "defconfig" build, this feature adds canary checks to
492 about 3% of all kernel functions, which increases kernel code size
495 config STACKPROTECTOR_STRONG
496 bool "Strong Stack Protector"
497 depends on STACKPROTECTOR
498 depends on $(cc-option,-fstack-protector-strong)
501 Functions will have the stack-protector canary logic added in any
502 of the following conditions:
504 - local variable's address used as part of the right hand side of an
505 assignment or function argument
506 - local variable is an array (or union containing an array),
507 regardless of array type or length
508 - uses register local variables
510 This feature requires gcc version 4.9 or above, or a distribution
511 gcc with the feature backported ("-fstack-protector-strong").
513 On an x86 "defconfig" build, this feature adds canary checks to
514 about 20% of all kernel functions, which increases the kernel code
517 config HAVE_ARCH_WITHIN_STACK_FRAMES
520 An architecture should select this if it can walk the kernel stack
521 frames to determine if an object is part of either the arguments
522 or local variables (i.e. that it excludes saved return addresses,
523 and similar) by implementing an inline arch_within_stack_frames(),
524 which is used by CONFIG_HARDENED_USERCOPY.
526 config HAVE_CONTEXT_TRACKING
529 Provide kernel/user boundaries probes necessary for subsystems
530 that need it, such as userspace RCU extended quiescent state.
531 Syscalls need to be wrapped inside user_exit()-user_enter() through
532 the slow path using TIF_NOHZ flag. Exceptions handlers must be
533 wrapped as well. Irqs are already protected inside
534 rcu_irq_enter/rcu_irq_exit() but preemption or signal handling on
535 irq exit still need to be protected.
537 config HAVE_VIRT_CPU_ACCOUNTING
540 config ARCH_HAS_SCALED_CPUTIME
543 config HAVE_VIRT_CPU_ACCOUNTING_GEN
547 With VIRT_CPU_ACCOUNTING_GEN, cputime_t becomes 64-bit.
548 Before enabling this option, arch code must be audited
549 to ensure there are no races in concurrent read/write of
550 cputime_t. For example, reading/writing 64-bit cputime_t on
551 some 32-bit arches may require multiple accesses, so proper
552 locking is needed to protect against concurrent accesses.
555 config HAVE_IRQ_TIME_ACCOUNTING
558 Archs need to ensure they use a high enough resolution clock to
559 support irq time accounting and then call enable_sched_clock_irqtime().
564 Archs that select this are able to move page tables at the PMD level.
566 config HAVE_ARCH_TRANSPARENT_HUGEPAGE
569 config HAVE_ARCH_TRANSPARENT_HUGEPAGE_PUD
572 config HAVE_ARCH_HUGE_VMAP
575 config ARCH_WANT_HUGE_PMD_SHARE
578 config HAVE_ARCH_SOFT_DIRTY
581 config HAVE_MOD_ARCH_SPECIFIC
584 The arch uses struct mod_arch_specific to store data. Many arches
585 just need a simple module loader without arch specific data - those
586 should not enable this.
588 config MODULES_USE_ELF_RELA
591 Modules only use ELF RELA relocations. Modules with ELF REL
592 relocations will give an error.
594 config MODULES_USE_ELF_REL
597 Modules only use ELF REL relocations. Modules with ELF RELA
598 relocations will give an error.
600 config HAVE_IRQ_EXIT_ON_IRQ_STACK
603 Architecture doesn't only execute the irq handler on the irq stack
604 but also irq_exit(). This way we can process softirqs on this irq
605 stack instead of switching to a new one when we call __do_softirq()
606 in the end of an hardirq.
607 This spares a stack switch and improves cache usage on softirq
610 config PGTABLE_LEVELS
614 config ARCH_HAS_ELF_RANDOMIZE
617 An architecture supports choosing randomized locations for
618 stack, mmap, brk, and ET_DYN. Defined functions:
620 - arch_randomize_brk()
622 config HAVE_ARCH_MMAP_RND_BITS
625 An arch should select this symbol if it supports setting a variable
626 number of bits for use in establishing the base address for mmap
627 allocations, has MMU enabled and provides values for both:
628 - ARCH_MMAP_RND_BITS_MIN
629 - ARCH_MMAP_RND_BITS_MAX
631 config HAVE_EXIT_THREAD
634 An architecture implements exit_thread.
636 config ARCH_MMAP_RND_BITS_MIN
639 config ARCH_MMAP_RND_BITS_MAX
642 config ARCH_MMAP_RND_BITS_DEFAULT
645 config ARCH_MMAP_RND_BITS
646 int "Number of bits to use for ASLR of mmap base address" if EXPERT
647 range ARCH_MMAP_RND_BITS_MIN ARCH_MMAP_RND_BITS_MAX
648 default ARCH_MMAP_RND_BITS_DEFAULT if ARCH_MMAP_RND_BITS_DEFAULT
649 default ARCH_MMAP_RND_BITS_MIN
650 depends on HAVE_ARCH_MMAP_RND_BITS
652 This value can be used to select the number of bits to use to
653 determine the random offset to the base address of vma regions
654 resulting from mmap allocations. This value will be bounded
655 by the architecture's minimum and maximum supported values.
657 This value can be changed after boot using the
658 /proc/sys/vm/mmap_rnd_bits tunable
660 config HAVE_ARCH_MMAP_RND_COMPAT_BITS
663 An arch should select this symbol if it supports running applications
664 in compatibility mode, supports setting a variable number of bits for
665 use in establishing the base address for mmap allocations, has MMU
666 enabled and provides values for both:
667 - ARCH_MMAP_RND_COMPAT_BITS_MIN
668 - ARCH_MMAP_RND_COMPAT_BITS_MAX
670 config ARCH_MMAP_RND_COMPAT_BITS_MIN
673 config ARCH_MMAP_RND_COMPAT_BITS_MAX
676 config ARCH_MMAP_RND_COMPAT_BITS_DEFAULT
679 config ARCH_MMAP_RND_COMPAT_BITS
680 int "Number of bits to use for ASLR of mmap base address for compatible applications" if EXPERT
681 range ARCH_MMAP_RND_COMPAT_BITS_MIN ARCH_MMAP_RND_COMPAT_BITS_MAX
682 default ARCH_MMAP_RND_COMPAT_BITS_DEFAULT if ARCH_MMAP_RND_COMPAT_BITS_DEFAULT
683 default ARCH_MMAP_RND_COMPAT_BITS_MIN
684 depends on HAVE_ARCH_MMAP_RND_COMPAT_BITS
686 This value can be used to select the number of bits to use to
687 determine the random offset to the base address of vma regions
688 resulting from mmap allocations for compatible applications This
689 value will be bounded by the architecture's minimum and maximum
692 This value can be changed after boot using the
693 /proc/sys/vm/mmap_rnd_compat_bits tunable
695 config HAVE_ARCH_COMPAT_MMAP_BASES
698 This allows 64bit applications to invoke 32-bit mmap() syscall
699 and vice-versa 32-bit applications to call 64-bit mmap().
700 Required for applications doing different bitness syscalls.
702 config HAVE_COPY_THREAD_TLS
705 Architecture provides copy_thread_tls to accept tls argument via
706 normal C parameter passing, rather than extracting the syscall
707 argument from pt_regs.
709 config HAVE_STACK_VALIDATION
712 Architecture supports the 'objtool check' host tool command, which
713 performs compile-time stack metadata validation.
715 config HAVE_RELIABLE_STACKTRACE
718 Architecture has a save_stack_trace_tsk_reliable() function which
719 only returns a stack trace if it can guarantee the trace is reliable.
721 config HAVE_ARCH_HASH
725 If this is set, the architecture provides an <asm/hash.h>
726 file which provides platform-specific implementations of some
727 functions in <linux/hash.h> or fs/namei.c.
729 config HAVE_ARCH_NVRAM_OPS
738 config CLONE_BACKWARDS
741 Architecture has tls passed as the 4th argument of clone(2),
744 config CLONE_BACKWARDS2
747 Architecture has the first two arguments of clone(2) swapped.
749 config CLONE_BACKWARDS3
752 Architecture has tls passed as the 3rd argument of clone(2),
755 config ODD_RT_SIGACTION
758 Architecture has unusual rt_sigaction(2) arguments
760 config OLD_SIGSUSPEND
763 Architecture has old sigsuspend(2) syscall, of one-argument variety
765 config OLD_SIGSUSPEND3
768 Even weirder antique ABI - three-argument sigsuspend(2)
773 Architecture has old sigaction(2) syscall. Nope, not the same
774 as OLD_SIGSUSPEND | OLD_SIGSUSPEND3 - alpha has sigsuspend(2),
775 but fairly different variant of sigaction(2), thanks to OSF/1
778 config COMPAT_OLD_SIGACTION
784 This should be selected by all architectures that need to support
785 new system calls with a 64-bit time_t. This is relevant on all 32-bit
786 architectures, and 64-bit architectures as part of compat syscall
789 config COMPAT_32BIT_TIME
790 def_bool !64BIT || COMPAT
792 This enables 32 bit time_t support in addition to 64 bit time_t support.
793 This is relevant on all 32-bit architectures, and 64-bit architectures
794 as part of compat syscall handling.
796 config ARCH_NO_COHERENT_DMA_MMAP
799 config ARCH_NO_PREEMPT
802 config ARCH_SUPPORTS_RT
805 config CPU_NO_EFFICIENT_FFS
808 config HAVE_ARCH_VMAP_STACK
811 An arch should select this symbol if it can support kernel stacks
812 in vmalloc space. This means:
814 - vmalloc space must be large enough to hold many kernel stacks.
815 This may rule out many 32-bit architectures.
817 - Stacks in vmalloc space need to work reliably. For example, if
818 vmap page tables are created on demand, either this mechanism
819 needs to work while the stack points to a virtual address with
820 unpopulated page tables or arch code (switch_to() and switch_mm(),
821 most likely) needs to ensure that the stack's page table entries
822 are populated before running on a possibly unpopulated stack.
824 - If the stack overflows into a guard page, something reasonable
825 should happen. The definition of "reasonable" is flexible, but
826 instantly rebooting without logging anything would be unfriendly.
830 bool "Use a virtually-mapped stack"
831 depends on HAVE_ARCH_VMAP_STACK && !KASAN
833 Enable this if you want the use virtually-mapped kernel stacks
834 with guard pages. This causes kernel stack overflows to be
835 caught immediately rather than causing difficult-to-diagnose
838 This is presently incompatible with KASAN because KASAN expects
839 the stack to map directly to the KASAN shadow map using a formula
840 that is incorrect if the stack is in vmalloc space.
842 config ARCH_OPTIONAL_KERNEL_RWX
845 config ARCH_OPTIONAL_KERNEL_RWX_DEFAULT
848 config ARCH_HAS_STRICT_KERNEL_RWX
851 config STRICT_KERNEL_RWX
852 bool "Make kernel text and rodata read-only" if ARCH_OPTIONAL_KERNEL_RWX
853 depends on ARCH_HAS_STRICT_KERNEL_RWX
854 default !ARCH_OPTIONAL_KERNEL_RWX || ARCH_OPTIONAL_KERNEL_RWX_DEFAULT
856 If this is set, kernel text and rodata memory will be made read-only,
857 and non-text memory will be made non-executable. This provides
858 protection against certain security exploits (e.g. executing the heap
861 These features are considered standard security practice these days.
862 You should say Y here in almost all cases.
864 config ARCH_HAS_STRICT_MODULE_RWX
867 config STRICT_MODULE_RWX
868 bool "Set loadable kernel module data as NX and text as RO" if ARCH_OPTIONAL_KERNEL_RWX
869 depends on ARCH_HAS_STRICT_MODULE_RWX && MODULES
870 default !ARCH_OPTIONAL_KERNEL_RWX || ARCH_OPTIONAL_KERNEL_RWX_DEFAULT
872 If this is set, module text and rodata memory will be made read-only,
873 and non-text memory will be made non-executable. This provides
874 protection against certain security exploits (e.g. writing to text)
876 # select if the architecture provides an asm/dma-direct.h header
877 config ARCH_HAS_PHYS_TO_DMA
880 config ARCH_HAS_REFCOUNT
883 An architecture selects this when it has implemented refcount_t
884 using open coded assembly primitives that provide an optimized
885 refcount_t implementation, possibly at the expense of some full
886 refcount state checks of CONFIG_REFCOUNT_FULL=y.
888 The refcount overflow check behavior, however, must be retained.
889 Catching overflows is the primary security concern for protecting
890 against bugs in reference counts.
893 bool "Perform full reference count validation at the expense of speed"
895 Enabling this switches the refcounting infrastructure from a fast
896 unchecked atomic_t implementation to a fully state checked
897 implementation, which can be (slightly) slower but provides protections
898 against various use-after-free conditions that can be used in
899 security flaw exploits.
901 config HAVE_ARCH_COMPILER_H
904 An architecture can select this if it provides an
905 asm/compiler.h header that should be included after
906 linux/compiler-*.h in order to override macro definitions that those
907 headers generally provide.
909 config HAVE_ARCH_PREL32_RELOCATIONS
912 May be selected by an architecture if it supports place-relative
913 32-bit relocations, both in the toolchain and in the module loader,
914 in which case relative references can be used in special sections
915 for PCI fixup, initcalls etc which are only half the size on 64 bit
916 architectures, and don't require runtime relocation on relocatable
919 config ARCH_USE_MEMREMAP_PROT
922 config LOCK_EVENT_COUNTS
923 bool "Locking event counts collection"
926 Enable light-weight counting of various locking related events
927 in the system with minimal performance impact. This reduces
928 the chance of application behavior change because of timing
929 differences. The counts are reported via debugfs.
931 # Select if the architecture has support for applying RELR relocations.
936 bool "Use RELR relocation packing"
937 depends on ARCH_HAS_RELR && TOOLS_SUPPORT_RELR
940 Store the kernel's dynamic relocations in the RELR relocation packing
941 format. Requires a compatible linker (LLD supports this feature), as
942 well as compatible NM and OBJCOPY utilities (llvm-nm and llvm-objcopy
945 source "kernel/gcov/Kconfig"
947 source "scripts/gcc-plugins/Kconfig"