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"
28 tristate "OProfile system profiling"
30 depends on HAVE_OPROFILE
32 select RING_BUFFER_ALLOW_SWAP
34 OProfile is a profiling system capable of profiling the
35 whole system, include the kernel, kernel modules, libraries,
40 config OPROFILE_EVENT_MULTIPLEX
41 bool "OProfile multiplexing support (EXPERIMENTAL)"
43 depends on OPROFILE && X86
45 The number of hardware counters is limited. The multiplexing
46 feature enables OProfile to gather more events than counters
47 are provided by the hardware. This is realized by switching
48 between events at a user specified time interval.
55 config OPROFILE_NMI_TIMER
57 depends on PERF_EVENTS && HAVE_PERF_EVENTS_NMI && !PPC64
62 depends on HAVE_KPROBES
65 Kprobes allows you to trap at almost any kernel address and
66 execute a callback function. register_kprobe() establishes
67 a probepoint and specifies the callback. Kprobes is useful
68 for kernel debugging, non-intrusive instrumentation and testing.
72 bool "Optimize very unlikely/likely branches"
73 depends on HAVE_ARCH_JUMP_LABEL
74 depends on CC_HAS_ASM_GOTO
76 This option enables a transparent branch optimization that
77 makes certain almost-always-true or almost-always-false branch
78 conditions even cheaper to execute within the kernel.
80 Certain performance-sensitive kernel code, such as trace points,
81 scheduler functionality, networking code and KVM have such
82 branches and include support for this optimization technique.
84 If it is detected that the compiler has support for "asm goto",
85 the kernel will compile such branches with just a nop
86 instruction. When the condition flag is toggled to true, the
87 nop will be converted to a jump instruction to execute the
88 conditional block of instructions.
90 This technique lowers overhead and stress on the branch prediction
91 of the processor and generally makes the kernel faster. The update
92 of the condition is slower, but those are always very rare.
94 ( On 32-bit x86, the necessary options added to the compiler
95 flags may increase the size of the kernel slightly. )
97 config STATIC_KEYS_SELFTEST
98 bool "Static key selftest"
101 Boot time self-test of the branch patching code.
105 depends on KPROBES && HAVE_OPTPROBES
106 select TASKS_RCU if PREEMPT
108 config KPROBES_ON_FTRACE
110 depends on KPROBES && HAVE_KPROBES_ON_FTRACE
111 depends on DYNAMIC_FTRACE_WITH_REGS
113 If function tracer is enabled and the arch supports full
114 passing of pt_regs to function tracing, then kprobes can
115 optimize on top of function tracing.
119 depends on ARCH_SUPPORTS_UPROBES
121 Uprobes is the user-space counterpart to kprobes: they
122 enable instrumentation applications (such as 'perf probe')
123 to establish unintrusive probes in user-space binaries and
124 libraries, by executing handler functions when the probes
125 are hit by user-space applications.
127 ( These probes come in the form of single-byte breakpoints,
128 managed by the kernel and kept transparent to the probed
131 config HAVE_EFFICIENT_UNALIGNED_ACCESS
134 Some architectures are unable to perform unaligned accesses
135 without the use of get_unaligned/put_unaligned. Others are
136 unable to perform such accesses efficiently (e.g. trap on
137 unaligned access and require fixing it up in the exception
140 This symbol should be selected by an architecture if it can
141 perform unaligned accesses efficiently to allow different
142 code paths to be selected for these cases. Some network
143 drivers, for example, could opt to not fix up alignment
144 problems with received packets if doing so would not help
147 See Documentation/unaligned-memory-access.txt for more
148 information on the topic of unaligned memory accesses.
150 config ARCH_USE_BUILTIN_BSWAP
153 Modern versions of GCC (since 4.4) have builtin functions
154 for handling byte-swapping. Using these, instead of the old
155 inline assembler that the architecture code provides in the
156 __arch_bswapXX() macros, allows the compiler to see what's
157 happening and offers more opportunity for optimisation. In
158 particular, the compiler will be able to combine the byteswap
159 with a nearby load or store and use load-and-swap or
160 store-and-swap instructions if the architecture has them. It
161 should almost *never* result in code which is worse than the
162 hand-coded assembler in <asm/swab.h>. But just in case it
163 does, the use of the builtins is optional.
165 Any architecture with load-and-swap or store-and-swap
166 instructions should set this. And it shouldn't hurt to set it
167 on architectures that don't have such instructions.
171 depends on KPROBES && HAVE_KRETPROBES
173 config USER_RETURN_NOTIFIER
175 depends on HAVE_USER_RETURN_NOTIFIER
177 Provide a kernel-internal notification when a cpu is about to
180 config HAVE_IOREMAP_PROT
186 config HAVE_KRETPROBES
189 config HAVE_OPTPROBES
192 config HAVE_KPROBES_ON_FTRACE
195 config HAVE_FUNCTION_ERROR_INJECTION
202 # An arch should select this if it provides all these things:
204 # task_pt_regs() in asm/processor.h or asm/ptrace.h
205 # arch_has_single_step() if there is hardware single-step support
206 # arch_has_block_step() if there is hardware block-step support
207 # asm/syscall.h supplying asm-generic/syscall.h interface
208 # linux/regset.h user_regset interfaces
209 # CORE_DUMP_USE_REGSET #define'd in linux/elf.h
210 # TIF_SYSCALL_TRACE calls tracehook_report_syscall_{entry,exit}
211 # TIF_NOTIFY_RESUME calls tracehook_notify_resume()
212 # signal delivery calls tracehook_signal_handler()
214 config HAVE_ARCH_TRACEHOOK
217 config HAVE_DMA_CONTIGUOUS
220 config GENERIC_SMP_IDLE_THREAD
223 config GENERIC_IDLE_POLL_SETUP
226 config ARCH_HAS_FORTIFY_SOURCE
229 An architecture should select this when it can successfully
230 build and run with CONFIG_FORTIFY_SOURCE.
233 # Select if the arch provides a historic keepinit alias for the retain_initrd
234 # command line option
236 config ARCH_HAS_KEEPINITRD
239 # Select if arch has all set_memory_ro/rw/x/nx() functions in asm/cacheflush.h
240 config ARCH_HAS_SET_MEMORY
243 # Select if arch has all set_direct_map_invalid/default() functions
244 config ARCH_HAS_SET_DIRECT_MAP
248 # Select if arch has an uncached kernel segment and provides the
249 # uncached_kernel_address / cached_kernel_address symbols to use it
251 config ARCH_HAS_UNCACHED_SEGMENT
252 select ARCH_HAS_DMA_PREP_COHERENT
255 # Select if arch init_task must go in the __init_task_data section
256 config ARCH_TASK_STRUCT_ON_STACK
259 # Select if arch has its private alloc_task_struct() function
260 config ARCH_TASK_STRUCT_ALLOCATOR
263 config HAVE_ARCH_THREAD_STRUCT_WHITELIST
265 depends on !ARCH_TASK_STRUCT_ALLOCATOR
267 An architecture should select this to provide hardened usercopy
268 knowledge about what region of the thread_struct should be
269 whitelisted for copying to userspace. Normally this is only the
270 FPU registers. Specifically, arch_thread_struct_whitelist()
271 should be implemented. Without this, the entire thread_struct
272 field in task_struct will be left whitelisted.
274 # Select if arch has its private alloc_thread_stack() function
275 config ARCH_THREAD_STACK_ALLOCATOR
278 # Select if arch wants to size task_struct dynamically via arch_task_struct_size:
279 config ARCH_WANTS_DYNAMIC_TASK_STRUCT
282 config ARCH_32BIT_OFF_T
286 All new 32-bit architectures should have 64-bit off_t type on
287 userspace side which corresponds to the loff_t kernel type. This
288 is the requirement for modern ABIs. Some existing architectures
289 still support 32-bit off_t. This option is enabled for all such
290 architectures explicitly.
292 config HAVE_ASM_MODVERSIONS
295 This symbol should be selected by an architecure if it provides
296 <asm/asm-prototypes.h> to support the module versioning for symbols
297 exported from assembly code.
299 config HAVE_REGS_AND_STACK_ACCESS_API
302 This symbol should be selected by an architecure if it supports
303 the API needed to access registers and stack entries from pt_regs,
304 declared in asm/ptrace.h
305 For example the kprobes-based event tracer needs this API.
309 depends on HAVE_REGS_AND_STACK_ACCESS_API
311 This symbol should be selected by an architecture if it
312 supports an implementation of restartable sequences.
314 config HAVE_FUNCTION_ARG_ACCESS_API
317 This symbol should be selected by an architecure if it supports
318 the API needed to access function arguments from pt_regs,
319 declared in asm/ptrace.h
324 The <linux/clk.h> calls support software clock gating and
325 thus are a key power management tool on many systems.
327 config HAVE_HW_BREAKPOINT
329 depends on PERF_EVENTS
331 config HAVE_MIXED_BREAKPOINTS_REGS
333 depends on HAVE_HW_BREAKPOINT
335 Depending on the arch implementation of hardware breakpoints,
336 some of them have separate registers for data and instruction
337 breakpoints addresses, others have mixed registers to store
338 them but define the access type in a control register.
339 Select this option if your arch implements breakpoints under the
342 config HAVE_USER_RETURN_NOTIFIER
345 config HAVE_PERF_EVENTS_NMI
348 System hardware can generate an NMI using the perf event
349 subsystem. Also has support for calculating CPU cycle events
350 to determine how many clock cycles in a given period.
352 config HAVE_HARDLOCKUP_DETECTOR_PERF
354 depends on HAVE_PERF_EVENTS_NMI
356 The arch chooses to use the generic perf-NMI-based hardlockup
357 detector. Must define HAVE_PERF_EVENTS_NMI.
359 config HAVE_NMI_WATCHDOG
363 The arch provides a low level NMI watchdog. It provides
364 asm/nmi.h, and defines its own arch_touch_nmi_watchdog().
366 config HAVE_HARDLOCKUP_DETECTOR_ARCH
368 select HAVE_NMI_WATCHDOG
370 The arch chooses to provide its own hardlockup detector, which is
371 a superset of the HAVE_NMI_WATCHDOG. It also conforms to config
372 interfaces and parameters provided by hardlockup detector subsystem.
374 config HAVE_PERF_REGS
377 Support selective register dumps for perf events. This includes
378 bit-mapping of each registers and a unique architecture id.
380 config HAVE_PERF_USER_STACK_DUMP
383 Support user stack dumps for perf event samples. This needs
384 access to the user stack pointer which is not unified across
387 config HAVE_ARCH_JUMP_LABEL
390 config HAVE_ARCH_JUMP_LABEL_RELATIVE
393 config HAVE_RCU_TABLE_FREE
396 config HAVE_RCU_TABLE_NO_INVALIDATE
399 config HAVE_MMU_GATHER_PAGE_SIZE
402 config HAVE_MMU_GATHER_NO_GATHER
405 config ARCH_HAVE_NMI_SAFE_CMPXCHG
408 config HAVE_ALIGNED_STRUCT_PAGE
411 This makes sure that struct pages are double word aligned and that
412 e.g. the SLUB allocator can perform double word atomic operations
413 on a struct page for better performance. However selecting this
414 might increase the size of a struct page by a word.
416 config HAVE_CMPXCHG_LOCAL
419 config HAVE_CMPXCHG_DOUBLE
422 config ARCH_WEAK_RELEASE_ACQUIRE
425 config ARCH_WANT_IPC_PARSE_VERSION
428 config ARCH_WANT_COMPAT_IPC_PARSE_VERSION
431 config ARCH_WANT_OLD_COMPAT_IPC
432 select ARCH_WANT_COMPAT_IPC_PARSE_VERSION
435 config HAVE_ARCH_SECCOMP_FILTER
438 An arch should select this symbol if it provides all of these things:
440 - syscall_get_arguments()
442 - syscall_set_return_value()
443 - SIGSYS siginfo_t support
444 - secure_computing is called from a ptrace_event()-safe context
445 - secure_computing return value is checked and a return value of -1
446 results in the system call being skipped immediately.
447 - seccomp syscall wired up
449 config SECCOMP_FILTER
451 depends on HAVE_ARCH_SECCOMP_FILTER && SECCOMP && NET
453 Enable tasks to build secure computing environments defined
454 in terms of Berkeley Packet Filter programs which implement
455 task-defined system call filtering polices.
457 See Documentation/userspace-api/seccomp_filter.rst for details.
459 config HAVE_ARCH_STACKLEAK
462 An architecture should select this if it has the code which
463 fills the used part of the kernel stack with the STACKLEAK_POISON
464 value before returning from system calls.
466 config HAVE_STACKPROTECTOR
469 An arch should select this symbol if:
470 - it has implemented a stack canary (e.g. __stack_chk_guard)
472 config CC_HAS_STACKPROTECTOR_NONE
473 def_bool $(cc-option,-fno-stack-protector)
475 config STACKPROTECTOR
476 bool "Stack Protector buffer overflow detection"
477 depends on HAVE_STACKPROTECTOR
478 depends on $(cc-option,-fstack-protector)
481 This option turns on the "stack-protector" GCC feature. This
482 feature puts, at the beginning of functions, a canary value on
483 the stack just before the return address, and validates
484 the value just before actually returning. Stack based buffer
485 overflows (that need to overwrite this return address) now also
486 overwrite the canary, which gets detected and the attack is then
487 neutralized via a kernel panic.
489 Functions will have the stack-protector canary logic added if they
490 have an 8-byte or larger character array on the stack.
492 This feature requires gcc version 4.2 or above, or a distribution
493 gcc with the feature backported ("-fstack-protector").
495 On an x86 "defconfig" build, this feature adds canary checks to
496 about 3% of all kernel functions, which increases kernel code size
499 config STACKPROTECTOR_STRONG
500 bool "Strong Stack Protector"
501 depends on STACKPROTECTOR
502 depends on $(cc-option,-fstack-protector-strong)
505 Functions will have the stack-protector canary logic added in any
506 of the following conditions:
508 - local variable's address used as part of the right hand side of an
509 assignment or function argument
510 - local variable is an array (or union containing an array),
511 regardless of array type or length
512 - uses register local variables
514 This feature requires gcc version 4.9 or above, or a distribution
515 gcc with the feature backported ("-fstack-protector-strong").
517 On an x86 "defconfig" build, this feature adds canary checks to
518 about 20% of all kernel functions, which increases the kernel code
521 config HAVE_ARCH_WITHIN_STACK_FRAMES
524 An architecture should select this if it can walk the kernel stack
525 frames to determine if an object is part of either the arguments
526 or local variables (i.e. that it excludes saved return addresses,
527 and similar) by implementing an inline arch_within_stack_frames(),
528 which is used by CONFIG_HARDENED_USERCOPY.
530 config HAVE_CONTEXT_TRACKING
533 Provide kernel/user boundaries probes necessary for subsystems
534 that need it, such as userspace RCU extended quiescent state.
535 Syscalls need to be wrapped inside user_exit()-user_enter() through
536 the slow path using TIF_NOHZ flag. Exceptions handlers must be
537 wrapped as well. Irqs are already protected inside
538 rcu_irq_enter/rcu_irq_exit() but preemption or signal handling on
539 irq exit still need to be protected.
541 config HAVE_VIRT_CPU_ACCOUNTING
544 config ARCH_HAS_SCALED_CPUTIME
547 config HAVE_VIRT_CPU_ACCOUNTING_GEN
551 With VIRT_CPU_ACCOUNTING_GEN, cputime_t becomes 64-bit.
552 Before enabling this option, arch code must be audited
553 to ensure there are no races in concurrent read/write of
554 cputime_t. For example, reading/writing 64-bit cputime_t on
555 some 32-bit arches may require multiple accesses, so proper
556 locking is needed to protect against concurrent accesses.
559 config HAVE_IRQ_TIME_ACCOUNTING
562 Archs need to ensure they use a high enough resolution clock to
563 support irq time accounting and then call enable_sched_clock_irqtime().
568 Archs that select this are able to move page tables at the PMD level.
570 config HAVE_ARCH_TRANSPARENT_HUGEPAGE
573 config HAVE_ARCH_TRANSPARENT_HUGEPAGE_PUD
576 config HAVE_ARCH_HUGE_VMAP
579 config ARCH_WANT_HUGE_PMD_SHARE
582 config HAVE_ARCH_SOFT_DIRTY
585 config HAVE_MOD_ARCH_SPECIFIC
588 The arch uses struct mod_arch_specific to store data. Many arches
589 just need a simple module loader without arch specific data - those
590 should not enable this.
592 config MODULES_USE_ELF_RELA
595 Modules only use ELF RELA relocations. Modules with ELF REL
596 relocations will give an error.
598 config MODULES_USE_ELF_REL
601 Modules only use ELF REL relocations. Modules with ELF RELA
602 relocations will give an error.
604 config HAVE_IRQ_EXIT_ON_IRQ_STACK
607 Architecture doesn't only execute the irq handler on the irq stack
608 but also irq_exit(). This way we can process softirqs on this irq
609 stack instead of switching to a new one when we call __do_softirq()
610 in the end of an hardirq.
611 This spares a stack switch and improves cache usage on softirq
614 config PGTABLE_LEVELS
618 config ARCH_HAS_ELF_RANDOMIZE
621 An architecture supports choosing randomized locations for
622 stack, mmap, brk, and ET_DYN. Defined functions:
624 - arch_randomize_brk()
626 config HAVE_ARCH_MMAP_RND_BITS
629 An arch should select this symbol if it supports setting a variable
630 number of bits for use in establishing the base address for mmap
631 allocations, has MMU enabled and provides values for both:
632 - ARCH_MMAP_RND_BITS_MIN
633 - ARCH_MMAP_RND_BITS_MAX
635 config HAVE_EXIT_THREAD
638 An architecture implements exit_thread.
640 config ARCH_MMAP_RND_BITS_MIN
643 config ARCH_MMAP_RND_BITS_MAX
646 config ARCH_MMAP_RND_BITS_DEFAULT
649 config ARCH_MMAP_RND_BITS
650 int "Number of bits to use for ASLR of mmap base address" if EXPERT
651 range ARCH_MMAP_RND_BITS_MIN ARCH_MMAP_RND_BITS_MAX
652 default ARCH_MMAP_RND_BITS_DEFAULT if ARCH_MMAP_RND_BITS_DEFAULT
653 default ARCH_MMAP_RND_BITS_MIN
654 depends on HAVE_ARCH_MMAP_RND_BITS
656 This value can be used to select the number of bits to use to
657 determine the random offset to the base address of vma regions
658 resulting from mmap allocations. This value will be bounded
659 by the architecture's minimum and maximum supported values.
661 This value can be changed after boot using the
662 /proc/sys/vm/mmap_rnd_bits tunable
664 config HAVE_ARCH_MMAP_RND_COMPAT_BITS
667 An arch should select this symbol if it supports running applications
668 in compatibility mode, supports setting a variable number of bits for
669 use in establishing the base address for mmap allocations, has MMU
670 enabled and provides values for both:
671 - ARCH_MMAP_RND_COMPAT_BITS_MIN
672 - ARCH_MMAP_RND_COMPAT_BITS_MAX
674 config ARCH_MMAP_RND_COMPAT_BITS_MIN
677 config ARCH_MMAP_RND_COMPAT_BITS_MAX
680 config ARCH_MMAP_RND_COMPAT_BITS_DEFAULT
683 config ARCH_MMAP_RND_COMPAT_BITS
684 int "Number of bits to use for ASLR of mmap base address for compatible applications" if EXPERT
685 range ARCH_MMAP_RND_COMPAT_BITS_MIN ARCH_MMAP_RND_COMPAT_BITS_MAX
686 default ARCH_MMAP_RND_COMPAT_BITS_DEFAULT if ARCH_MMAP_RND_COMPAT_BITS_DEFAULT
687 default ARCH_MMAP_RND_COMPAT_BITS_MIN
688 depends on HAVE_ARCH_MMAP_RND_COMPAT_BITS
690 This value can be used to select the number of bits to use to
691 determine the random offset to the base address of vma regions
692 resulting from mmap allocations for compatible applications This
693 value will be bounded by the architecture's minimum and maximum
696 This value can be changed after boot using the
697 /proc/sys/vm/mmap_rnd_compat_bits tunable
699 config HAVE_ARCH_COMPAT_MMAP_BASES
702 This allows 64bit applications to invoke 32-bit mmap() syscall
703 and vice-versa 32-bit applications to call 64-bit mmap().
704 Required for applications doing different bitness syscalls.
706 config HAVE_COPY_THREAD_TLS
709 Architecture provides copy_thread_tls to accept tls argument via
710 normal C parameter passing, rather than extracting the syscall
711 argument from pt_regs.
713 config HAVE_STACK_VALIDATION
716 Architecture supports the 'objtool check' host tool command, which
717 performs compile-time stack metadata validation.
719 config HAVE_RELIABLE_STACKTRACE
722 Architecture has a save_stack_trace_tsk_reliable() function which
723 only returns a stack trace if it can guarantee the trace is reliable.
725 config HAVE_ARCH_HASH
729 If this is set, the architecture provides an <asm/hash.h>
730 file which provides platform-specific implementations of some
731 functions in <linux/hash.h> or fs/namei.c.
733 config HAVE_ARCH_NVRAM_OPS
742 config CLONE_BACKWARDS
745 Architecture has tls passed as the 4th argument of clone(2),
748 config CLONE_BACKWARDS2
751 Architecture has the first two arguments of clone(2) swapped.
753 config CLONE_BACKWARDS3
756 Architecture has tls passed as the 3rd argument of clone(2),
759 config ODD_RT_SIGACTION
762 Architecture has unusual rt_sigaction(2) arguments
764 config OLD_SIGSUSPEND
767 Architecture has old sigsuspend(2) syscall, of one-argument variety
769 config OLD_SIGSUSPEND3
772 Even weirder antique ABI - three-argument sigsuspend(2)
777 Architecture has old sigaction(2) syscall. Nope, not the same
778 as OLD_SIGSUSPEND | OLD_SIGSUSPEND3 - alpha has sigsuspend(2),
779 but fairly different variant of sigaction(2), thanks to OSF/1
782 config COMPAT_OLD_SIGACTION
788 This should be selected by all architectures that need to support
789 new system calls with a 64-bit time_t. This is relevant on all 32-bit
790 architectures, and 64-bit architectures as part of compat syscall
793 config COMPAT_32BIT_TIME
794 def_bool !64BIT || COMPAT
796 This enables 32 bit time_t support in addition to 64 bit time_t support.
797 This is relevant on all 32-bit architectures, and 64-bit architectures
798 as part of compat syscall handling.
800 config ARCH_NO_COHERENT_DMA_MMAP
803 config ARCH_NO_PREEMPT
806 config ARCH_SUPPORTS_RT
809 config CPU_NO_EFFICIENT_FFS
812 config HAVE_ARCH_VMAP_STACK
815 An arch should select this symbol if it can support kernel stacks
816 in vmalloc space. This means:
818 - vmalloc space must be large enough to hold many kernel stacks.
819 This may rule out many 32-bit architectures.
821 - Stacks in vmalloc space need to work reliably. For example, if
822 vmap page tables are created on demand, either this mechanism
823 needs to work while the stack points to a virtual address with
824 unpopulated page tables or arch code (switch_to() and switch_mm(),
825 most likely) needs to ensure that the stack's page table entries
826 are populated before running on a possibly unpopulated stack.
828 - If the stack overflows into a guard page, something reasonable
829 should happen. The definition of "reasonable" is flexible, but
830 instantly rebooting without logging anything would be unfriendly.
834 bool "Use a virtually-mapped stack"
835 depends on HAVE_ARCH_VMAP_STACK && !KASAN
837 Enable this if you want the use virtually-mapped kernel stacks
838 with guard pages. This causes kernel stack overflows to be
839 caught immediately rather than causing difficult-to-diagnose
842 This is presently incompatible with KASAN because KASAN expects
843 the stack to map directly to the KASAN shadow map using a formula
844 that is incorrect if the stack is in vmalloc space.
846 config ARCH_OPTIONAL_KERNEL_RWX
849 config ARCH_OPTIONAL_KERNEL_RWX_DEFAULT
852 config ARCH_HAS_STRICT_KERNEL_RWX
855 config STRICT_KERNEL_RWX
856 bool "Make kernel text and rodata read-only" if ARCH_OPTIONAL_KERNEL_RWX
857 depends on ARCH_HAS_STRICT_KERNEL_RWX
858 default !ARCH_OPTIONAL_KERNEL_RWX || ARCH_OPTIONAL_KERNEL_RWX_DEFAULT
860 If this is set, kernel text and rodata memory will be made read-only,
861 and non-text memory will be made non-executable. This provides
862 protection against certain security exploits (e.g. executing the heap
865 These features are considered standard security practice these days.
866 You should say Y here in almost all cases.
868 config ARCH_HAS_STRICT_MODULE_RWX
871 config STRICT_MODULE_RWX
872 bool "Set loadable kernel module data as NX and text as RO" if ARCH_OPTIONAL_KERNEL_RWX
873 depends on ARCH_HAS_STRICT_MODULE_RWX && MODULES
874 default !ARCH_OPTIONAL_KERNEL_RWX || ARCH_OPTIONAL_KERNEL_RWX_DEFAULT
876 If this is set, module text and rodata memory will be made read-only,
877 and non-text memory will be made non-executable. This provides
878 protection against certain security exploits (e.g. writing to text)
880 # select if the architecture provides an asm/dma-direct.h header
881 config ARCH_HAS_PHYS_TO_DMA
884 config ARCH_HAS_REFCOUNT
887 An architecture selects this when it has implemented refcount_t
888 using open coded assembly primitives that provide an optimized
889 refcount_t implementation, possibly at the expense of some full
890 refcount state checks of CONFIG_REFCOUNT_FULL=y.
892 The refcount overflow check behavior, however, must be retained.
893 Catching overflows is the primary security concern for protecting
894 against bugs in reference counts.
897 bool "Perform full reference count validation at the expense of speed"
899 Enabling this switches the refcounting infrastructure from a fast
900 unchecked atomic_t implementation to a fully state checked
901 implementation, which can be (slightly) slower but provides protections
902 against various use-after-free conditions that can be used in
903 security flaw exploits.
905 config HAVE_ARCH_COMPILER_H
908 An architecture can select this if it provides an
909 asm/compiler.h header that should be included after
910 linux/compiler-*.h in order to override macro definitions that those
911 headers generally provide.
913 config HAVE_ARCH_PREL32_RELOCATIONS
916 May be selected by an architecture if it supports place-relative
917 32-bit relocations, both in the toolchain and in the module loader,
918 in which case relative references can be used in special sections
919 for PCI fixup, initcalls etc which are only half the size on 64 bit
920 architectures, and don't require runtime relocation on relocatable
923 config ARCH_USE_MEMREMAP_PROT
926 config LOCK_EVENT_COUNTS
927 bool "Locking event counts collection"
930 Enable light-weight counting of various locking related events
931 in the system with minimal performance impact. This reduces
932 the chance of application behavior change because of timing
933 differences. The counts are reported via debugfs.
935 source "kernel/gcov/Kconfig"
937 source "scripts/gcc-plugins/Kconfig"