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_64BIT_ALIGNED_ACCESS
132 def_bool 64BIT && !HAVE_EFFICIENT_UNALIGNED_ACCESS
134 Some architectures require 64 bit accesses to be 64 bit
135 aligned, which also requires structs containing 64 bit values
136 to be 64 bit aligned too. This includes some 32 bit
137 architectures which can do 64 bit accesses, as well as 64 bit
138 architectures without unaligned access.
140 This symbol should be selected by an architecture if 64 bit
141 accesses are required to be 64 bit aligned in this way even
142 though it is not a 64 bit architecture.
144 See Documentation/unaligned-memory-access.txt for more
145 information on the topic of unaligned memory accesses.
147 config HAVE_EFFICIENT_UNALIGNED_ACCESS
150 Some architectures are unable to perform unaligned accesses
151 without the use of get_unaligned/put_unaligned. Others are
152 unable to perform such accesses efficiently (e.g. trap on
153 unaligned access and require fixing it up in the exception
156 This symbol should be selected by an architecture if it can
157 perform unaligned accesses efficiently to allow different
158 code paths to be selected for these cases. Some network
159 drivers, for example, could opt to not fix up alignment
160 problems with received packets if doing so would not help
163 See Documentation/unaligned-memory-access.txt for more
164 information on the topic of unaligned memory accesses.
166 config ARCH_USE_BUILTIN_BSWAP
169 Modern versions of GCC (since 4.4) have builtin functions
170 for handling byte-swapping. Using these, instead of the old
171 inline assembler that the architecture code provides in the
172 __arch_bswapXX() macros, allows the compiler to see what's
173 happening and offers more opportunity for optimisation. In
174 particular, the compiler will be able to combine the byteswap
175 with a nearby load or store and use load-and-swap or
176 store-and-swap instructions if the architecture has them. It
177 should almost *never* result in code which is worse than the
178 hand-coded assembler in <asm/swab.h>. But just in case it
179 does, the use of the builtins is optional.
181 Any architecture with load-and-swap or store-and-swap
182 instructions should set this. And it shouldn't hurt to set it
183 on architectures that don't have such instructions.
187 depends on KPROBES && HAVE_KRETPROBES
189 config USER_RETURN_NOTIFIER
191 depends on HAVE_USER_RETURN_NOTIFIER
193 Provide a kernel-internal notification when a cpu is about to
196 config HAVE_IOREMAP_PROT
202 config HAVE_KRETPROBES
205 config HAVE_OPTPROBES
208 config HAVE_KPROBES_ON_FTRACE
211 config HAVE_FUNCTION_ERROR_INJECTION
218 # An arch should select this if it provides all these things:
220 # task_pt_regs() in asm/processor.h or asm/ptrace.h
221 # arch_has_single_step() if there is hardware single-step support
222 # arch_has_block_step() if there is hardware block-step support
223 # asm/syscall.h supplying asm-generic/syscall.h interface
224 # linux/regset.h user_regset interfaces
225 # CORE_DUMP_USE_REGSET #define'd in linux/elf.h
226 # TIF_SYSCALL_TRACE calls tracehook_report_syscall_{entry,exit}
227 # TIF_NOTIFY_RESUME calls tracehook_notify_resume()
228 # signal delivery calls tracehook_signal_handler()
230 config HAVE_ARCH_TRACEHOOK
233 config HAVE_DMA_CONTIGUOUS
236 config GENERIC_SMP_IDLE_THREAD
239 config GENERIC_IDLE_POLL_SETUP
242 config ARCH_HAS_FORTIFY_SOURCE
245 An architecture should select this when it can successfully
246 build and run with CONFIG_FORTIFY_SOURCE.
248 # Select if arch has all set_memory_ro/rw/x/nx() functions in asm/cacheflush.h
249 config ARCH_HAS_SET_MEMORY
252 # Select if arch has all set_direct_map_invalid/default() functions
253 config ARCH_HAS_SET_DIRECT_MAP
256 # Select if arch init_task must go in the __init_task_data section
257 config ARCH_TASK_STRUCT_ON_STACK
260 # Select if arch has its private alloc_task_struct() function
261 config ARCH_TASK_STRUCT_ALLOCATOR
264 config HAVE_ARCH_THREAD_STRUCT_WHITELIST
266 depends on !ARCH_TASK_STRUCT_ALLOCATOR
268 An architecture should select this to provide hardened usercopy
269 knowledge about what region of the thread_struct should be
270 whitelisted for copying to userspace. Normally this is only the
271 FPU registers. Specifically, arch_thread_struct_whitelist()
272 should be implemented. Without this, the entire thread_struct
273 field in task_struct will be left whitelisted.
275 # Select if arch has its private alloc_thread_stack() function
276 config ARCH_THREAD_STACK_ALLOCATOR
279 # Select if arch wants to size task_struct dynamically via arch_task_struct_size:
280 config ARCH_WANTS_DYNAMIC_TASK_STRUCT
283 config ARCH_32BIT_OFF_T
287 All new 32-bit architectures should have 64-bit off_t type on
288 userspace side which corresponds to the loff_t kernel type. This
289 is the requirement for modern ABIs. Some existing architectures
290 still support 32-bit off_t. This option is enabled for all such
291 architectures explicitly.
293 config HAVE_REGS_AND_STACK_ACCESS_API
296 This symbol should be selected by an architecure if it supports
297 the API needed to access registers and stack entries from pt_regs,
298 declared in asm/ptrace.h
299 For example the kprobes-based event tracer needs this API.
303 depends on HAVE_REGS_AND_STACK_ACCESS_API
305 This symbol should be selected by an architecture if it
306 supports an implementation of restartable sequences.
308 config HAVE_FUNCTION_ARG_ACCESS_API
311 This symbol should be selected by an architecure if it supports
312 the API needed to access function arguments from pt_regs,
313 declared in asm/ptrace.h
318 The <linux/clk.h> calls support software clock gating and
319 thus are a key power management tool on many systems.
321 config HAVE_HW_BREAKPOINT
323 depends on PERF_EVENTS
325 config HAVE_MIXED_BREAKPOINTS_REGS
327 depends on HAVE_HW_BREAKPOINT
329 Depending on the arch implementation of hardware breakpoints,
330 some of them have separate registers for data and instruction
331 breakpoints addresses, others have mixed registers to store
332 them but define the access type in a control register.
333 Select this option if your arch implements breakpoints under the
336 config HAVE_USER_RETURN_NOTIFIER
339 config HAVE_PERF_EVENTS_NMI
342 System hardware can generate an NMI using the perf event
343 subsystem. Also has support for calculating CPU cycle events
344 to determine how many clock cycles in a given period.
346 config HAVE_HARDLOCKUP_DETECTOR_PERF
348 depends on HAVE_PERF_EVENTS_NMI
350 The arch chooses to use the generic perf-NMI-based hardlockup
351 detector. Must define HAVE_PERF_EVENTS_NMI.
353 config HAVE_NMI_WATCHDOG
357 The arch provides a low level NMI watchdog. It provides
358 asm/nmi.h, and defines its own arch_touch_nmi_watchdog().
360 config HAVE_HARDLOCKUP_DETECTOR_ARCH
362 select HAVE_NMI_WATCHDOG
364 The arch chooses to provide its own hardlockup detector, which is
365 a superset of the HAVE_NMI_WATCHDOG. It also conforms to config
366 interfaces and parameters provided by hardlockup detector subsystem.
368 config HAVE_PERF_REGS
371 Support selective register dumps for perf events. This includes
372 bit-mapping of each registers and a unique architecture id.
374 config HAVE_PERF_USER_STACK_DUMP
377 Support user stack dumps for perf event samples. This needs
378 access to the user stack pointer which is not unified across
381 config HAVE_ARCH_JUMP_LABEL
384 config HAVE_ARCH_JUMP_LABEL_RELATIVE
387 config HAVE_RCU_TABLE_FREE
390 config HAVE_RCU_TABLE_NO_INVALIDATE
393 config HAVE_MMU_GATHER_PAGE_SIZE
396 config HAVE_MMU_GATHER_NO_GATHER
399 config ARCH_HAVE_NMI_SAFE_CMPXCHG
402 config HAVE_ALIGNED_STRUCT_PAGE
405 This makes sure that struct pages are double word aligned and that
406 e.g. the SLUB allocator can perform double word atomic operations
407 on a struct page for better performance. However selecting this
408 might increase the size of a struct page by a word.
410 config HAVE_CMPXCHG_LOCAL
413 config HAVE_CMPXCHG_DOUBLE
416 config ARCH_WEAK_RELEASE_ACQUIRE
419 config ARCH_WANT_IPC_PARSE_VERSION
422 config ARCH_WANT_COMPAT_IPC_PARSE_VERSION
425 config ARCH_WANT_OLD_COMPAT_IPC
426 select ARCH_WANT_COMPAT_IPC_PARSE_VERSION
429 config HAVE_ARCH_SECCOMP_FILTER
432 An arch should select this symbol if it provides all of these things:
434 - syscall_get_arguments()
436 - syscall_set_return_value()
437 - SIGSYS siginfo_t support
438 - secure_computing is called from a ptrace_event()-safe context
439 - secure_computing return value is checked and a return value of -1
440 results in the system call being skipped immediately.
441 - seccomp syscall wired up
443 config SECCOMP_FILTER
445 depends on HAVE_ARCH_SECCOMP_FILTER && SECCOMP && NET
447 Enable tasks to build secure computing environments defined
448 in terms of Berkeley Packet Filter programs which implement
449 task-defined system call filtering polices.
451 See Documentation/userspace-api/seccomp_filter.rst for details.
453 config HAVE_ARCH_STACKLEAK
456 An architecture should select this if it has the code which
457 fills the used part of the kernel stack with the STACKLEAK_POISON
458 value before returning from system calls.
460 config HAVE_STACKPROTECTOR
463 An arch should select this symbol if:
464 - it has implemented a stack canary (e.g. __stack_chk_guard)
466 config CC_HAS_STACKPROTECTOR_NONE
467 def_bool $(cc-option,-fno-stack-protector)
469 config STACKPROTECTOR
470 bool "Stack Protector buffer overflow detection"
471 depends on HAVE_STACKPROTECTOR
472 depends on $(cc-option,-fstack-protector)
475 This option turns on the "stack-protector" GCC feature. This
476 feature puts, at the beginning of functions, a canary value on
477 the stack just before the return address, and validates
478 the value just before actually returning. Stack based buffer
479 overflows (that need to overwrite this return address) now also
480 overwrite the canary, which gets detected and the attack is then
481 neutralized via a kernel panic.
483 Functions will have the stack-protector canary logic added if they
484 have an 8-byte or larger character array on the stack.
486 This feature requires gcc version 4.2 or above, or a distribution
487 gcc with the feature backported ("-fstack-protector").
489 On an x86 "defconfig" build, this feature adds canary checks to
490 about 3% of all kernel functions, which increases kernel code size
493 config STACKPROTECTOR_STRONG
494 bool "Strong Stack Protector"
495 depends on STACKPROTECTOR
496 depends on $(cc-option,-fstack-protector-strong)
499 Functions will have the stack-protector canary logic added in any
500 of the following conditions:
502 - local variable's address used as part of the right hand side of an
503 assignment or function argument
504 - local variable is an array (or union containing an array),
505 regardless of array type or length
506 - uses register local variables
508 This feature requires gcc version 4.9 or above, or a distribution
509 gcc with the feature backported ("-fstack-protector-strong").
511 On an x86 "defconfig" build, this feature adds canary checks to
512 about 20% of all kernel functions, which increases the kernel code
515 config HAVE_ARCH_WITHIN_STACK_FRAMES
518 An architecture should select this if it can walk the kernel stack
519 frames to determine if an object is part of either the arguments
520 or local variables (i.e. that it excludes saved return addresses,
521 and similar) by implementing an inline arch_within_stack_frames(),
522 which is used by CONFIG_HARDENED_USERCOPY.
524 config HAVE_CONTEXT_TRACKING
527 Provide kernel/user boundaries probes necessary for subsystems
528 that need it, such as userspace RCU extended quiescent state.
529 Syscalls need to be wrapped inside user_exit()-user_enter() through
530 the slow path using TIF_NOHZ flag. Exceptions handlers must be
531 wrapped as well. Irqs are already protected inside
532 rcu_irq_enter/rcu_irq_exit() but preemption or signal handling on
533 irq exit still need to be protected.
535 config HAVE_VIRT_CPU_ACCOUNTING
538 config ARCH_HAS_SCALED_CPUTIME
541 config HAVE_VIRT_CPU_ACCOUNTING_GEN
545 With VIRT_CPU_ACCOUNTING_GEN, cputime_t becomes 64-bit.
546 Before enabling this option, arch code must be audited
547 to ensure there are no races in concurrent read/write of
548 cputime_t. For example, reading/writing 64-bit cputime_t on
549 some 32-bit arches may require multiple accesses, so proper
550 locking is needed to protect against concurrent accesses.
553 config HAVE_IRQ_TIME_ACCOUNTING
556 Archs need to ensure they use a high enough resolution clock to
557 support irq time accounting and then call enable_sched_clock_irqtime().
562 Archs that select this are able to move page tables at the PMD level.
564 config HAVE_ARCH_TRANSPARENT_HUGEPAGE
567 config HAVE_ARCH_TRANSPARENT_HUGEPAGE_PUD
570 config HAVE_ARCH_HUGE_VMAP
573 config HAVE_ARCH_SOFT_DIRTY
576 config HAVE_MOD_ARCH_SPECIFIC
579 The arch uses struct mod_arch_specific to store data. Many arches
580 just need a simple module loader without arch specific data - those
581 should not enable this.
583 config MODULES_USE_ELF_RELA
586 Modules only use ELF RELA relocations. Modules with ELF REL
587 relocations will give an error.
589 config MODULES_USE_ELF_REL
592 Modules only use ELF REL relocations. Modules with ELF RELA
593 relocations will give an error.
595 config HAVE_IRQ_EXIT_ON_IRQ_STACK
598 Architecture doesn't only execute the irq handler on the irq stack
599 but also irq_exit(). This way we can process softirqs on this irq
600 stack instead of switching to a new one when we call __do_softirq()
601 in the end of an hardirq.
602 This spares a stack switch and improves cache usage on softirq
605 config PGTABLE_LEVELS
609 config ARCH_HAS_ELF_RANDOMIZE
612 An architecture supports choosing randomized locations for
613 stack, mmap, brk, and ET_DYN. Defined functions:
615 - arch_randomize_brk()
617 config HAVE_ARCH_MMAP_RND_BITS
620 An arch should select this symbol if it supports setting a variable
621 number of bits for use in establishing the base address for mmap
622 allocations, has MMU enabled and provides values for both:
623 - ARCH_MMAP_RND_BITS_MIN
624 - ARCH_MMAP_RND_BITS_MAX
626 config HAVE_EXIT_THREAD
629 An architecture implements exit_thread.
631 config ARCH_MMAP_RND_BITS_MIN
634 config ARCH_MMAP_RND_BITS_MAX
637 config ARCH_MMAP_RND_BITS_DEFAULT
640 config ARCH_MMAP_RND_BITS
641 int "Number of bits to use for ASLR of mmap base address" if EXPERT
642 range ARCH_MMAP_RND_BITS_MIN ARCH_MMAP_RND_BITS_MAX
643 default ARCH_MMAP_RND_BITS_DEFAULT if ARCH_MMAP_RND_BITS_DEFAULT
644 default ARCH_MMAP_RND_BITS_MIN
645 depends on HAVE_ARCH_MMAP_RND_BITS
647 This value can be used to select the number of bits to use to
648 determine the random offset to the base address of vma regions
649 resulting from mmap allocations. This value will be bounded
650 by the architecture's minimum and maximum supported values.
652 This value can be changed after boot using the
653 /proc/sys/vm/mmap_rnd_bits tunable
655 config HAVE_ARCH_MMAP_RND_COMPAT_BITS
658 An arch should select this symbol if it supports running applications
659 in compatibility mode, supports setting a variable number of bits for
660 use in establishing the base address for mmap allocations, has MMU
661 enabled and provides values for both:
662 - ARCH_MMAP_RND_COMPAT_BITS_MIN
663 - ARCH_MMAP_RND_COMPAT_BITS_MAX
665 config ARCH_MMAP_RND_COMPAT_BITS_MIN
668 config ARCH_MMAP_RND_COMPAT_BITS_MAX
671 config ARCH_MMAP_RND_COMPAT_BITS_DEFAULT
674 config ARCH_MMAP_RND_COMPAT_BITS
675 int "Number of bits to use for ASLR of mmap base address for compatible applications" if EXPERT
676 range ARCH_MMAP_RND_COMPAT_BITS_MIN ARCH_MMAP_RND_COMPAT_BITS_MAX
677 default ARCH_MMAP_RND_COMPAT_BITS_DEFAULT if ARCH_MMAP_RND_COMPAT_BITS_DEFAULT
678 default ARCH_MMAP_RND_COMPAT_BITS_MIN
679 depends on HAVE_ARCH_MMAP_RND_COMPAT_BITS
681 This value can be used to select the number of bits to use to
682 determine the random offset to the base address of vma regions
683 resulting from mmap allocations for compatible applications This
684 value will be bounded by the architecture's minimum and maximum
687 This value can be changed after boot using the
688 /proc/sys/vm/mmap_rnd_compat_bits tunable
690 config HAVE_ARCH_COMPAT_MMAP_BASES
693 This allows 64bit applications to invoke 32-bit mmap() syscall
694 and vice-versa 32-bit applications to call 64-bit mmap().
695 Required for applications doing different bitness syscalls.
697 config HAVE_COPY_THREAD_TLS
700 Architecture provides copy_thread_tls to accept tls argument via
701 normal C parameter passing, rather than extracting the syscall
702 argument from pt_regs.
704 config HAVE_STACK_VALIDATION
707 Architecture supports the 'objtool check' host tool command, which
708 performs compile-time stack metadata validation.
710 config HAVE_RELIABLE_STACKTRACE
713 Architecture has a save_stack_trace_tsk_reliable() function which
714 only returns a stack trace if it can guarantee the trace is reliable.
716 config HAVE_ARCH_HASH
720 If this is set, the architecture provides an <asm/hash.h>
721 file which provides platform-specific implementations of some
722 functions in <linux/hash.h> or fs/namei.c.
724 config HAVE_ARCH_NVRAM_OPS
733 config CLONE_BACKWARDS
736 Architecture has tls passed as the 4th argument of clone(2),
739 config CLONE_BACKWARDS2
742 Architecture has the first two arguments of clone(2) swapped.
744 config CLONE_BACKWARDS3
747 Architecture has tls passed as the 3rd argument of clone(2),
750 config ODD_RT_SIGACTION
753 Architecture has unusual rt_sigaction(2) arguments
755 config OLD_SIGSUSPEND
758 Architecture has old sigsuspend(2) syscall, of one-argument variety
760 config OLD_SIGSUSPEND3
763 Even weirder antique ABI - three-argument sigsuspend(2)
768 Architecture has old sigaction(2) syscall. Nope, not the same
769 as OLD_SIGSUSPEND | OLD_SIGSUSPEND3 - alpha has sigsuspend(2),
770 but fairly different variant of sigaction(2), thanks to OSF/1
773 config COMPAT_OLD_SIGACTION
777 def_bool ARCH_HAS_64BIT_TIME
779 This should be selected by all architectures that need to support
780 new system calls with a 64-bit time_t. This is relevant on all 32-bit
781 architectures, and 64-bit architectures as part of compat syscall
784 config COMPAT_32BIT_TIME
785 def_bool !64BIT || COMPAT
787 This enables 32 bit time_t support in addition to 64 bit time_t support.
788 This is relevant on all 32-bit architectures, and 64-bit architectures
789 as part of compat syscall handling.
791 config ARCH_NO_COHERENT_DMA_MMAP
794 config ARCH_NO_PREEMPT
797 config CPU_NO_EFFICIENT_FFS
800 config HAVE_ARCH_VMAP_STACK
803 An arch should select this symbol if it can support kernel stacks
804 in vmalloc space. This means:
806 - vmalloc space must be large enough to hold many kernel stacks.
807 This may rule out many 32-bit architectures.
809 - Stacks in vmalloc space need to work reliably. For example, if
810 vmap page tables are created on demand, either this mechanism
811 needs to work while the stack points to a virtual address with
812 unpopulated page tables or arch code (switch_to() and switch_mm(),
813 most likely) needs to ensure that the stack's page table entries
814 are populated before running on a possibly unpopulated stack.
816 - If the stack overflows into a guard page, something reasonable
817 should happen. The definition of "reasonable" is flexible, but
818 instantly rebooting without logging anything would be unfriendly.
822 bool "Use a virtually-mapped stack"
823 depends on HAVE_ARCH_VMAP_STACK && !KASAN
825 Enable this if you want the use virtually-mapped kernel stacks
826 with guard pages. This causes kernel stack overflows to be
827 caught immediately rather than causing difficult-to-diagnose
830 This is presently incompatible with KASAN because KASAN expects
831 the stack to map directly to the KASAN shadow map using a formula
832 that is incorrect if the stack is in vmalloc space.
834 config ARCH_OPTIONAL_KERNEL_RWX
837 config ARCH_OPTIONAL_KERNEL_RWX_DEFAULT
840 config ARCH_HAS_STRICT_KERNEL_RWX
843 config STRICT_KERNEL_RWX
844 bool "Make kernel text and rodata read-only" if ARCH_OPTIONAL_KERNEL_RWX
845 depends on ARCH_HAS_STRICT_KERNEL_RWX
846 default !ARCH_OPTIONAL_KERNEL_RWX || ARCH_OPTIONAL_KERNEL_RWX_DEFAULT
848 If this is set, kernel text and rodata memory will be made read-only,
849 and non-text memory will be made non-executable. This provides
850 protection against certain security exploits (e.g. executing the heap
853 These features are considered standard security practice these days.
854 You should say Y here in almost all cases.
856 config ARCH_HAS_STRICT_MODULE_RWX
859 config STRICT_MODULE_RWX
860 bool "Set loadable kernel module data as NX and text as RO" if ARCH_OPTIONAL_KERNEL_RWX
861 depends on ARCH_HAS_STRICT_MODULE_RWX && MODULES
862 default !ARCH_OPTIONAL_KERNEL_RWX || ARCH_OPTIONAL_KERNEL_RWX_DEFAULT
864 If this is set, module text and rodata memory will be made read-only,
865 and non-text memory will be made non-executable. This provides
866 protection against certain security exploits (e.g. writing to text)
868 # select if the architecture provides an asm/dma-direct.h header
869 config ARCH_HAS_PHYS_TO_DMA
872 config ARCH_HAS_REFCOUNT
875 An architecture selects this when it has implemented refcount_t
876 using open coded assembly primitives that provide an optimized
877 refcount_t implementation, possibly at the expense of some full
878 refcount state checks of CONFIG_REFCOUNT_FULL=y.
880 The refcount overflow check behavior, however, must be retained.
881 Catching overflows is the primary security concern for protecting
882 against bugs in reference counts.
885 bool "Perform full reference count validation at the expense of speed"
887 Enabling this switches the refcounting infrastructure from a fast
888 unchecked atomic_t implementation to a fully state checked
889 implementation, which can be (slightly) slower but provides protections
890 against various use-after-free conditions that can be used in
891 security flaw exploits.
893 config HAVE_ARCH_COMPILER_H
896 An architecture can select this if it provides an
897 asm/compiler.h header that should be included after
898 linux/compiler-*.h in order to override macro definitions that those
899 headers generally provide.
901 config HAVE_ARCH_PREL32_RELOCATIONS
904 May be selected by an architecture if it supports place-relative
905 32-bit relocations, both in the toolchain and in the module loader,
906 in which case relative references can be used in special sections
907 for PCI fixup, initcalls etc which are only half the size on 64 bit
908 architectures, and don't require runtime relocation on relocatable
911 config ARCH_USE_MEMREMAP_PROT
914 config LOCK_EVENT_COUNTS
915 bool "Locking event counts collection"
918 Enable light-weight counting of various locking related events
919 in the system with minimal performance impact. This reduces
920 the chance of application behavior change because of timing
921 differences. The counts are reported via debugfs.
923 source "kernel/gcov/Kconfig"
925 source "scripts/gcc-plugins/Kconfig"