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
75 This option enables a transparent branch optimization that
76 makes certain almost-always-true or almost-always-false branch
77 conditions even cheaper to execute within the kernel.
79 Certain performance-sensitive kernel code, such as trace points,
80 scheduler functionality, networking code and KVM have such
81 branches and include support for this optimization technique.
83 If it is detected that the compiler has support for "asm goto",
84 the kernel will compile such branches with just a nop
85 instruction. When the condition flag is toggled to true, the
86 nop will be converted to a jump instruction to execute the
87 conditional block of instructions.
89 This technique lowers overhead and stress on the branch prediction
90 of the processor and generally makes the kernel faster. The update
91 of the condition is slower, but those are always very rare.
93 ( On 32-bit x86, the necessary options added to the compiler
94 flags may increase the size of the kernel slightly. )
96 config STATIC_KEYS_SELFTEST
97 bool "Static key selftest"
100 Boot time self-test of the branch patching code.
104 depends on KPROBES && HAVE_OPTPROBES
105 select TASKS_RCU if PREEMPT
107 config KPROBES_ON_FTRACE
109 depends on KPROBES && HAVE_KPROBES_ON_FTRACE
110 depends on DYNAMIC_FTRACE_WITH_REGS
112 If function tracer is enabled and the arch supports full
113 passing of pt_regs to function tracing, then kprobes can
114 optimize on top of function tracing.
118 depends on ARCH_SUPPORTS_UPROBES
120 Uprobes is the user-space counterpart to kprobes: they
121 enable instrumentation applications (such as 'perf probe')
122 to establish unintrusive probes in user-space binaries and
123 libraries, by executing handler functions when the probes
124 are hit by user-space applications.
126 ( These probes come in the form of single-byte breakpoints,
127 managed by the kernel and kept transparent to the probed
130 config HAVE_64BIT_ALIGNED_ACCESS
131 def_bool 64BIT && !HAVE_EFFICIENT_UNALIGNED_ACCESS
133 Some architectures require 64 bit accesses to be 64 bit
134 aligned, which also requires structs containing 64 bit values
135 to be 64 bit aligned too. This includes some 32 bit
136 architectures which can do 64 bit accesses, as well as 64 bit
137 architectures without unaligned access.
139 This symbol should be selected by an architecture if 64 bit
140 accesses are required to be 64 bit aligned in this way even
141 though it is not a 64 bit architecture.
143 See Documentation/unaligned-memory-access.txt for more
144 information on the topic of unaligned memory accesses.
146 config HAVE_EFFICIENT_UNALIGNED_ACCESS
149 Some architectures are unable to perform unaligned accesses
150 without the use of get_unaligned/put_unaligned. Others are
151 unable to perform such accesses efficiently (e.g. trap on
152 unaligned access and require fixing it up in the exception
155 This symbol should be selected by an architecture if it can
156 perform unaligned accesses efficiently to allow different
157 code paths to be selected for these cases. Some network
158 drivers, for example, could opt to not fix up alignment
159 problems with received packets if doing so would not help
162 See Documentation/unaligned-memory-access.txt for more
163 information on the topic of unaligned memory accesses.
165 config ARCH_USE_BUILTIN_BSWAP
168 Modern versions of GCC (since 4.4) have builtin functions
169 for handling byte-swapping. Using these, instead of the old
170 inline assembler that the architecture code provides in the
171 __arch_bswapXX() macros, allows the compiler to see what's
172 happening and offers more opportunity for optimisation. In
173 particular, the compiler will be able to combine the byteswap
174 with a nearby load or store and use load-and-swap or
175 store-and-swap instructions if the architecture has them. It
176 should almost *never* result in code which is worse than the
177 hand-coded assembler in <asm/swab.h>. But just in case it
178 does, the use of the builtins is optional.
180 Any architecture with load-and-swap or store-and-swap
181 instructions should set this. And it shouldn't hurt to set it
182 on architectures that don't have such instructions.
186 depends on KPROBES && HAVE_KRETPROBES
188 config USER_RETURN_NOTIFIER
190 depends on HAVE_USER_RETURN_NOTIFIER
192 Provide a kernel-internal notification when a cpu is about to
195 config HAVE_IOREMAP_PROT
201 config HAVE_KRETPROBES
204 config HAVE_OPTPROBES
207 config HAVE_KPROBES_ON_FTRACE
210 config HAVE_FUNCTION_ERROR_INJECTION
217 # An arch should select this if it provides all these things:
219 # task_pt_regs() in asm/processor.h or asm/ptrace.h
220 # arch_has_single_step() if there is hardware single-step support
221 # arch_has_block_step() if there is hardware block-step support
222 # asm/syscall.h supplying asm-generic/syscall.h interface
223 # linux/regset.h user_regset interfaces
224 # CORE_DUMP_USE_REGSET #define'd in linux/elf.h
225 # TIF_SYSCALL_TRACE calls tracehook_report_syscall_{entry,exit}
226 # TIF_NOTIFY_RESUME calls tracehook_notify_resume()
227 # signal delivery calls tracehook_signal_handler()
229 config HAVE_ARCH_TRACEHOOK
232 config HAVE_DMA_CONTIGUOUS
235 config GENERIC_SMP_IDLE_THREAD
238 config GENERIC_IDLE_POLL_SETUP
241 config ARCH_HAS_FORTIFY_SOURCE
244 An architecture should select this when it can successfully
245 build and run with CONFIG_FORTIFY_SOURCE.
247 # Select if arch has all set_memory_ro/rw/x/nx() functions in asm/cacheflush.h
248 config ARCH_HAS_SET_MEMORY
251 # Select if arch init_task must go in the __init_task_data section
252 config ARCH_TASK_STRUCT_ON_STACK
255 # Select if arch has its private alloc_task_struct() function
256 config ARCH_TASK_STRUCT_ALLOCATOR
259 config HAVE_ARCH_THREAD_STRUCT_WHITELIST
261 depends on !ARCH_TASK_STRUCT_ALLOCATOR
263 An architecture should select this to provide hardened usercopy
264 knowledge about what region of the thread_struct should be
265 whitelisted for copying to userspace. Normally this is only the
266 FPU registers. Specifically, arch_thread_struct_whitelist()
267 should be implemented. Without this, the entire thread_struct
268 field in task_struct will be left whitelisted.
270 # Select if arch has its private alloc_thread_stack() function
271 config ARCH_THREAD_STACK_ALLOCATOR
274 # Select if arch wants to size task_struct dynamically via arch_task_struct_size:
275 config ARCH_WANTS_DYNAMIC_TASK_STRUCT
278 config HAVE_REGS_AND_STACK_ACCESS_API
281 This symbol should be selected by an architecure if it supports
282 the API needed to access registers and stack entries from pt_regs,
283 declared in asm/ptrace.h
284 For example the kprobes-based event tracer needs this API.
288 depends on HAVE_REGS_AND_STACK_ACCESS_API
290 This symbol should be selected by an architecture if it
291 supports an implementation of restartable sequences.
296 The <linux/clk.h> calls support software clock gating and
297 thus are a key power management tool on many systems.
299 config HAVE_HW_BREAKPOINT
301 depends on PERF_EVENTS
303 config HAVE_MIXED_BREAKPOINTS_REGS
305 depends on HAVE_HW_BREAKPOINT
307 Depending on the arch implementation of hardware breakpoints,
308 some of them have separate registers for data and instruction
309 breakpoints addresses, others have mixed registers to store
310 them but define the access type in a control register.
311 Select this option if your arch implements breakpoints under the
314 config HAVE_USER_RETURN_NOTIFIER
317 config HAVE_PERF_EVENTS_NMI
320 System hardware can generate an NMI using the perf event
321 subsystem. Also has support for calculating CPU cycle events
322 to determine how many clock cycles in a given period.
324 config HAVE_HARDLOCKUP_DETECTOR_PERF
326 depends on HAVE_PERF_EVENTS_NMI
328 The arch chooses to use the generic perf-NMI-based hardlockup
329 detector. Must define HAVE_PERF_EVENTS_NMI.
331 config HAVE_NMI_WATCHDOG
335 The arch provides a low level NMI watchdog. It provides
336 asm/nmi.h, and defines its own arch_touch_nmi_watchdog().
338 config HAVE_HARDLOCKUP_DETECTOR_ARCH
340 select HAVE_NMI_WATCHDOG
342 The arch chooses to provide its own hardlockup detector, which is
343 a superset of the HAVE_NMI_WATCHDOG. It also conforms to config
344 interfaces and parameters provided by hardlockup detector subsystem.
346 config HAVE_PERF_REGS
349 Support selective register dumps for perf events. This includes
350 bit-mapping of each registers and a unique architecture id.
352 config HAVE_PERF_USER_STACK_DUMP
355 Support user stack dumps for perf event samples. This needs
356 access to the user stack pointer which is not unified across
359 config HAVE_ARCH_JUMP_LABEL
362 config HAVE_RCU_TABLE_FREE
365 config ARCH_HAVE_NMI_SAFE_CMPXCHG
368 config HAVE_ALIGNED_STRUCT_PAGE
371 This makes sure that struct pages are double word aligned and that
372 e.g. the SLUB allocator can perform double word atomic operations
373 on a struct page for better performance. However selecting this
374 might increase the size of a struct page by a word.
376 config HAVE_CMPXCHG_LOCAL
379 config HAVE_CMPXCHG_DOUBLE
382 config ARCH_WEAK_RELEASE_ACQUIRE
385 config ARCH_WANT_IPC_PARSE_VERSION
388 config ARCH_WANT_COMPAT_IPC_PARSE_VERSION
391 config ARCH_WANT_OLD_COMPAT_IPC
392 select ARCH_WANT_COMPAT_IPC_PARSE_VERSION
395 config HAVE_ARCH_SECCOMP_FILTER
398 An arch should select this symbol if it provides all of these things:
400 - syscall_get_arguments()
402 - syscall_set_return_value()
403 - SIGSYS siginfo_t support
404 - secure_computing is called from a ptrace_event()-safe context
405 - secure_computing return value is checked and a return value of -1
406 results in the system call being skipped immediately.
407 - seccomp syscall wired up
409 config SECCOMP_FILTER
411 depends on HAVE_ARCH_SECCOMP_FILTER && SECCOMP && NET
413 Enable tasks to build secure computing environments defined
414 in terms of Berkeley Packet Filter programs which implement
415 task-defined system call filtering polices.
417 See Documentation/userspace-api/seccomp_filter.rst for details.
419 config HAVE_STACKPROTECTOR
422 An arch should select this symbol if:
423 - it has implemented a stack canary (e.g. __stack_chk_guard)
425 config CC_HAS_STACKPROTECTOR_NONE
426 def_bool $(cc-option,-fno-stack-protector)
428 config STACKPROTECTOR
429 bool "Stack Protector buffer overflow detection"
430 depends on HAVE_STACKPROTECTOR
431 depends on $(cc-option,-fstack-protector)
434 This option turns on the "stack-protector" GCC feature. This
435 feature puts, at the beginning of functions, a canary value on
436 the stack just before the return address, and validates
437 the value just before actually returning. Stack based buffer
438 overflows (that need to overwrite this return address) now also
439 overwrite the canary, which gets detected and the attack is then
440 neutralized via a kernel panic.
442 Functions will have the stack-protector canary logic added if they
443 have an 8-byte or larger character array on the stack.
445 This feature requires gcc version 4.2 or above, or a distribution
446 gcc with the feature backported ("-fstack-protector").
448 On an x86 "defconfig" build, this feature adds canary checks to
449 about 3% of all kernel functions, which increases kernel code size
452 config STACKPROTECTOR_STRONG
453 bool "Strong Stack Protector"
454 depends on STACKPROTECTOR
455 depends on $(cc-option,-fstack-protector-strong)
458 Functions will have the stack-protector canary logic added in any
459 of the following conditions:
461 - local variable's address used as part of the right hand side of an
462 assignment or function argument
463 - local variable is an array (or union containing an array),
464 regardless of array type or length
465 - uses register local variables
467 This feature requires gcc version 4.9 or above, or a distribution
468 gcc with the feature backported ("-fstack-protector-strong").
470 On an x86 "defconfig" build, this feature adds canary checks to
471 about 20% of all kernel functions, which increases the kernel code
474 config HAVE_ARCH_WITHIN_STACK_FRAMES
477 An architecture should select this if it can walk the kernel stack
478 frames to determine if an object is part of either the arguments
479 or local variables (i.e. that it excludes saved return addresses,
480 and similar) by implementing an inline arch_within_stack_frames(),
481 which is used by CONFIG_HARDENED_USERCOPY.
483 config HAVE_CONTEXT_TRACKING
486 Provide kernel/user boundaries probes necessary for subsystems
487 that need it, such as userspace RCU extended quiescent state.
488 Syscalls need to be wrapped inside user_exit()-user_enter() through
489 the slow path using TIF_NOHZ flag. Exceptions handlers must be
490 wrapped as well. Irqs are already protected inside
491 rcu_irq_enter/rcu_irq_exit() but preemption or signal handling on
492 irq exit still need to be protected.
494 config HAVE_VIRT_CPU_ACCOUNTING
497 config ARCH_HAS_SCALED_CPUTIME
500 config HAVE_VIRT_CPU_ACCOUNTING_GEN
504 With VIRT_CPU_ACCOUNTING_GEN, cputime_t becomes 64-bit.
505 Before enabling this option, arch code must be audited
506 to ensure there are no races in concurrent read/write of
507 cputime_t. For example, reading/writing 64-bit cputime_t on
508 some 32-bit arches may require multiple accesses, so proper
509 locking is needed to protect against concurrent accesses.
512 config HAVE_IRQ_TIME_ACCOUNTING
515 Archs need to ensure they use a high enough resolution clock to
516 support irq time accounting and then call enable_sched_clock_irqtime().
518 config HAVE_ARCH_TRANSPARENT_HUGEPAGE
521 config HAVE_ARCH_TRANSPARENT_HUGEPAGE_PUD
524 config HAVE_ARCH_HUGE_VMAP
527 config HAVE_ARCH_SOFT_DIRTY
530 config HAVE_MOD_ARCH_SPECIFIC
533 The arch uses struct mod_arch_specific to store data. Many arches
534 just need a simple module loader without arch specific data - those
535 should not enable this.
537 config MODULES_USE_ELF_RELA
540 Modules only use ELF RELA relocations. Modules with ELF REL
541 relocations will give an error.
543 config MODULES_USE_ELF_REL
546 Modules only use ELF REL relocations. Modules with ELF RELA
547 relocations will give an error.
549 config HAVE_IRQ_EXIT_ON_IRQ_STACK
552 Architecture doesn't only execute the irq handler on the irq stack
553 but also irq_exit(). This way we can process softirqs on this irq
554 stack instead of switching to a new one when we call __do_softirq()
555 in the end of an hardirq.
556 This spares a stack switch and improves cache usage on softirq
559 config PGTABLE_LEVELS
563 config ARCH_HAS_ELF_RANDOMIZE
566 An architecture supports choosing randomized locations for
567 stack, mmap, brk, and ET_DYN. Defined functions:
569 - arch_randomize_brk()
571 config HAVE_ARCH_MMAP_RND_BITS
574 An arch should select this symbol if it supports setting a variable
575 number of bits for use in establishing the base address for mmap
576 allocations, has MMU enabled and provides values for both:
577 - ARCH_MMAP_RND_BITS_MIN
578 - ARCH_MMAP_RND_BITS_MAX
580 config HAVE_EXIT_THREAD
583 An architecture implements exit_thread.
585 config ARCH_MMAP_RND_BITS_MIN
588 config ARCH_MMAP_RND_BITS_MAX
591 config ARCH_MMAP_RND_BITS_DEFAULT
594 config ARCH_MMAP_RND_BITS
595 int "Number of bits to use for ASLR of mmap base address" if EXPERT
596 range ARCH_MMAP_RND_BITS_MIN ARCH_MMAP_RND_BITS_MAX
597 default ARCH_MMAP_RND_BITS_DEFAULT if ARCH_MMAP_RND_BITS_DEFAULT
598 default ARCH_MMAP_RND_BITS_MIN
599 depends on HAVE_ARCH_MMAP_RND_BITS
601 This value can be used to select the number of bits to use to
602 determine the random offset to the base address of vma regions
603 resulting from mmap allocations. This value will be bounded
604 by the architecture's minimum and maximum supported values.
606 This value can be changed after boot using the
607 /proc/sys/vm/mmap_rnd_bits tunable
609 config HAVE_ARCH_MMAP_RND_COMPAT_BITS
612 An arch should select this symbol if it supports running applications
613 in compatibility mode, supports setting a variable number of bits for
614 use in establishing the base address for mmap allocations, has MMU
615 enabled and provides values for both:
616 - ARCH_MMAP_RND_COMPAT_BITS_MIN
617 - ARCH_MMAP_RND_COMPAT_BITS_MAX
619 config ARCH_MMAP_RND_COMPAT_BITS_MIN
622 config ARCH_MMAP_RND_COMPAT_BITS_MAX
625 config ARCH_MMAP_RND_COMPAT_BITS_DEFAULT
628 config ARCH_MMAP_RND_COMPAT_BITS
629 int "Number of bits to use for ASLR of mmap base address for compatible applications" if EXPERT
630 range ARCH_MMAP_RND_COMPAT_BITS_MIN ARCH_MMAP_RND_COMPAT_BITS_MAX
631 default ARCH_MMAP_RND_COMPAT_BITS_DEFAULT if ARCH_MMAP_RND_COMPAT_BITS_DEFAULT
632 default ARCH_MMAP_RND_COMPAT_BITS_MIN
633 depends on HAVE_ARCH_MMAP_RND_COMPAT_BITS
635 This value can be used to select the number of bits to use to
636 determine the random offset to the base address of vma regions
637 resulting from mmap allocations for compatible applications This
638 value will be bounded by the architecture's minimum and maximum
641 This value can be changed after boot using the
642 /proc/sys/vm/mmap_rnd_compat_bits tunable
644 config HAVE_ARCH_COMPAT_MMAP_BASES
647 This allows 64bit applications to invoke 32-bit mmap() syscall
648 and vice-versa 32-bit applications to call 64-bit mmap().
649 Required for applications doing different bitness syscalls.
651 config HAVE_COPY_THREAD_TLS
654 Architecture provides copy_thread_tls to accept tls argument via
655 normal C parameter passing, rather than extracting the syscall
656 argument from pt_regs.
658 config HAVE_STACK_VALIDATION
661 Architecture supports the 'objtool check' host tool command, which
662 performs compile-time stack metadata validation.
664 config HAVE_RELIABLE_STACKTRACE
667 Architecture has a save_stack_trace_tsk_reliable() function which
668 only returns a stack trace if it can guarantee the trace is reliable.
670 config HAVE_ARCH_HASH
674 If this is set, the architecture provides an <asm/hash.h>
675 file which provides platform-specific implementations of some
676 functions in <linux/hash.h> or fs/namei.c.
684 config CLONE_BACKWARDS
687 Architecture has tls passed as the 4th argument of clone(2),
690 config CLONE_BACKWARDS2
693 Architecture has the first two arguments of clone(2) swapped.
695 config CLONE_BACKWARDS3
698 Architecture has tls passed as the 3rd argument of clone(2),
701 config ODD_RT_SIGACTION
704 Architecture has unusual rt_sigaction(2) arguments
706 config OLD_SIGSUSPEND
709 Architecture has old sigsuspend(2) syscall, of one-argument variety
711 config OLD_SIGSUSPEND3
714 Even weirder antique ABI - three-argument sigsuspend(2)
719 Architecture has old sigaction(2) syscall. Nope, not the same
720 as OLD_SIGSUSPEND | OLD_SIGSUSPEND3 - alpha has sigsuspend(2),
721 but fairly different variant of sigaction(2), thanks to OSF/1
724 config COMPAT_OLD_SIGACTION
728 def_bool ARCH_HAS_64BIT_TIME
730 This should be selected by all architectures that need to support
731 new system calls with a 64-bit time_t. This is relevant on all 32-bit
732 architectures, and 64-bit architectures as part of compat syscall
735 config COMPAT_32BIT_TIME
736 def_bool (!64BIT && 64BIT_TIME) || COMPAT
738 This enables 32 bit time_t support in addition to 64 bit time_t support.
739 This is relevant on all 32-bit architectures, and 64-bit architectures
740 as part of compat syscall handling.
742 config ARCH_NO_COHERENT_DMA_MMAP
745 config ARCH_NO_PREEMPT
748 config CPU_NO_EFFICIENT_FFS
751 config HAVE_ARCH_VMAP_STACK
754 An arch should select this symbol if it can support kernel stacks
755 in vmalloc space. This means:
757 - vmalloc space must be large enough to hold many kernel stacks.
758 This may rule out many 32-bit architectures.
760 - Stacks in vmalloc space need to work reliably. For example, if
761 vmap page tables are created on demand, either this mechanism
762 needs to work while the stack points to a virtual address with
763 unpopulated page tables or arch code (switch_to() and switch_mm(),
764 most likely) needs to ensure that the stack's page table entries
765 are populated before running on a possibly unpopulated stack.
767 - If the stack overflows into a guard page, something reasonable
768 should happen. The definition of "reasonable" is flexible, but
769 instantly rebooting without logging anything would be unfriendly.
773 bool "Use a virtually-mapped stack"
774 depends on HAVE_ARCH_VMAP_STACK && !KASAN
776 Enable this if you want the use virtually-mapped kernel stacks
777 with guard pages. This causes kernel stack overflows to be
778 caught immediately rather than causing difficult-to-diagnose
781 This is presently incompatible with KASAN because KASAN expects
782 the stack to map directly to the KASAN shadow map using a formula
783 that is incorrect if the stack is in vmalloc space.
785 config ARCH_OPTIONAL_KERNEL_RWX
788 config ARCH_OPTIONAL_KERNEL_RWX_DEFAULT
791 config ARCH_HAS_STRICT_KERNEL_RWX
794 config STRICT_KERNEL_RWX
795 bool "Make kernel text and rodata read-only" if ARCH_OPTIONAL_KERNEL_RWX
796 depends on ARCH_HAS_STRICT_KERNEL_RWX
797 default !ARCH_OPTIONAL_KERNEL_RWX || ARCH_OPTIONAL_KERNEL_RWX_DEFAULT
799 If this is set, kernel text and rodata memory will be made read-only,
800 and non-text memory will be made non-executable. This provides
801 protection against certain security exploits (e.g. executing the heap
804 These features are considered standard security practice these days.
805 You should say Y here in almost all cases.
807 config ARCH_HAS_STRICT_MODULE_RWX
810 config STRICT_MODULE_RWX
811 bool "Set loadable kernel module data as NX and text as RO" if ARCH_OPTIONAL_KERNEL_RWX
812 depends on ARCH_HAS_STRICT_MODULE_RWX && MODULES
813 default !ARCH_OPTIONAL_KERNEL_RWX || ARCH_OPTIONAL_KERNEL_RWX_DEFAULT
815 If this is set, module text and rodata memory will be made read-only,
816 and non-text memory will be made non-executable. This provides
817 protection against certain security exploits (e.g. writing to text)
819 # select if the architecture provides an asm/dma-direct.h header
820 config ARCH_HAS_PHYS_TO_DMA
823 config ARCH_HAS_REFCOUNT
826 An architecture selects this when it has implemented refcount_t
827 using open coded assembly primitives that provide an optimized
828 refcount_t implementation, possibly at the expense of some full
829 refcount state checks of CONFIG_REFCOUNT_FULL=y.
831 The refcount overflow check behavior, however, must be retained.
832 Catching overflows is the primary security concern for protecting
833 against bugs in reference counts.
836 bool "Perform full reference count validation at the expense of speed"
838 Enabling this switches the refcounting infrastructure from a fast
839 unchecked atomic_t implementation to a fully state checked
840 implementation, which can be (slightly) slower but provides protections
841 against various use-after-free conditions that can be used in
842 security flaw exploits.
844 config HAVE_ARCH_COMPILER_H
847 An architecture can select this if it provides an
848 asm/compiler.h header that should be included after
849 linux/compiler-*.h in order to override macro definitions that those
850 headers generally provide.
852 config HAVE_ARCH_PREL32_RELOCATIONS
855 May be selected by an architecture if it supports place-relative
856 32-bit relocations, both in the toolchain and in the module loader,
857 in which case relative references can be used in special sections
858 for PCI fixup, initcalls etc which are only half the size on 64 bit
859 architectures, and don't require runtime relocation on relocatable
862 source "kernel/gcov/Kconfig"
864 source "scripts/gcc-plugins/Kconfig"