1 # SPDX-License-Identifier: GPL-2.0
3 # General architecture dependent options
20 tristate "OProfile system profiling"
22 depends on HAVE_OPROFILE
24 select RING_BUFFER_ALLOW_SWAP
26 OProfile is a profiling system capable of profiling the
27 whole system, include the kernel, kernel modules, libraries,
32 config OPROFILE_EVENT_MULTIPLEX
33 bool "OProfile multiplexing support (EXPERIMENTAL)"
35 depends on OPROFILE && X86
37 The number of hardware counters is limited. The multiplexing
38 feature enables OProfile to gather more events than counters
39 are provided by the hardware. This is realized by switching
40 between events at a user specified time interval.
47 config OPROFILE_NMI_TIMER
49 depends on PERF_EVENTS && HAVE_PERF_EVENTS_NMI && !PPC64
54 depends on HAVE_KPROBES
57 Kprobes allows you to trap at almost any kernel address and
58 execute a callback function. register_kprobe() establishes
59 a probepoint and specifies the callback. Kprobes is useful
60 for kernel debugging, non-intrusive instrumentation and testing.
64 bool "Optimize very unlikely/likely branches"
65 depends on HAVE_ARCH_JUMP_LABEL
67 This option enables a transparent branch optimization that
68 makes certain almost-always-true or almost-always-false branch
69 conditions even cheaper to execute within the kernel.
71 Certain performance-sensitive kernel code, such as trace points,
72 scheduler functionality, networking code and KVM have such
73 branches and include support for this optimization technique.
75 If it is detected that the compiler has support for "asm goto",
76 the kernel will compile such branches with just a nop
77 instruction. When the condition flag is toggled to true, the
78 nop will be converted to a jump instruction to execute the
79 conditional block of instructions.
81 This technique lowers overhead and stress on the branch prediction
82 of the processor and generally makes the kernel faster. The update
83 of the condition is slower, but those are always very rare.
85 ( On 32-bit x86, the necessary options added to the compiler
86 flags may increase the size of the kernel slightly. )
88 config STATIC_KEYS_SELFTEST
89 bool "Static key selftest"
92 Boot time self-test of the branch patching code.
96 depends on KPROBES && HAVE_OPTPROBES
97 select TASKS_RCU if PREEMPT
99 config KPROBES_ON_FTRACE
101 depends on KPROBES && HAVE_KPROBES_ON_FTRACE
102 depends on DYNAMIC_FTRACE_WITH_REGS
104 If function tracer is enabled and the arch supports full
105 passing of pt_regs to function tracing, then kprobes can
106 optimize on top of function tracing.
110 depends on ARCH_SUPPORTS_UPROBES
112 Uprobes is the user-space counterpart to kprobes: they
113 enable instrumentation applications (such as 'perf probe')
114 to establish unintrusive probes in user-space binaries and
115 libraries, by executing handler functions when the probes
116 are hit by user-space applications.
118 ( These probes come in the form of single-byte breakpoints,
119 managed by the kernel and kept transparent to the probed
122 config HAVE_64BIT_ALIGNED_ACCESS
123 def_bool 64BIT && !HAVE_EFFICIENT_UNALIGNED_ACCESS
125 Some architectures require 64 bit accesses to be 64 bit
126 aligned, which also requires structs containing 64 bit values
127 to be 64 bit aligned too. This includes some 32 bit
128 architectures which can do 64 bit accesses, as well as 64 bit
129 architectures without unaligned access.
131 This symbol should be selected by an architecture if 64 bit
132 accesses are required to be 64 bit aligned in this way even
133 though it is not a 64 bit architecture.
135 See Documentation/unaligned-memory-access.txt for more
136 information on the topic of unaligned memory accesses.
138 config HAVE_EFFICIENT_UNALIGNED_ACCESS
141 Some architectures are unable to perform unaligned accesses
142 without the use of get_unaligned/put_unaligned. Others are
143 unable to perform such accesses efficiently (e.g. trap on
144 unaligned access and require fixing it up in the exception
147 This symbol should be selected by an architecture if it can
148 perform unaligned accesses efficiently to allow different
149 code paths to be selected for these cases. Some network
150 drivers, for example, could opt to not fix up alignment
151 problems with received packets if doing so would not help
154 See Documentation/unaligned-memory-access.txt for more
155 information on the topic of unaligned memory accesses.
157 config ARCH_USE_BUILTIN_BSWAP
160 Modern versions of GCC (since 4.4) have builtin functions
161 for handling byte-swapping. Using these, instead of the old
162 inline assembler that the architecture code provides in the
163 __arch_bswapXX() macros, allows the compiler to see what's
164 happening and offers more opportunity for optimisation. In
165 particular, the compiler will be able to combine the byteswap
166 with a nearby load or store and use load-and-swap or
167 store-and-swap instructions if the architecture has them. It
168 should almost *never* result in code which is worse than the
169 hand-coded assembler in <asm/swab.h>. But just in case it
170 does, the use of the builtins is optional.
172 Any architecture with load-and-swap or store-and-swap
173 instructions should set this. And it shouldn't hurt to set it
174 on architectures that don't have such instructions.
178 depends on KPROBES && HAVE_KRETPROBES
180 config USER_RETURN_NOTIFIER
182 depends on HAVE_USER_RETURN_NOTIFIER
184 Provide a kernel-internal notification when a cpu is about to
187 config HAVE_IOREMAP_PROT
193 config HAVE_KRETPROBES
196 config HAVE_OPTPROBES
199 config HAVE_KPROBES_ON_FTRACE
206 # An arch should select this if it provides all these things:
208 # task_pt_regs() in asm/processor.h or asm/ptrace.h
209 # arch_has_single_step() if there is hardware single-step support
210 # arch_has_block_step() if there is hardware block-step support
211 # asm/syscall.h supplying asm-generic/syscall.h interface
212 # linux/regset.h user_regset interfaces
213 # CORE_DUMP_USE_REGSET #define'd in linux/elf.h
214 # TIF_SYSCALL_TRACE calls tracehook_report_syscall_{entry,exit}
215 # TIF_NOTIFY_RESUME calls tracehook_notify_resume()
216 # signal delivery calls tracehook_signal_handler()
218 config HAVE_ARCH_TRACEHOOK
221 config HAVE_DMA_CONTIGUOUS
224 config GENERIC_SMP_IDLE_THREAD
227 config GENERIC_IDLE_POLL_SETUP
230 config ARCH_HAS_FORTIFY_SOURCE
233 An architecture should select this when it can successfully
234 build and run with CONFIG_FORTIFY_SOURCE.
236 # Select if arch has all set_memory_ro/rw/x/nx() functions in asm/cacheflush.h
237 config ARCH_HAS_SET_MEMORY
240 config ARCH_HAS_CPU_FINALIZE_INIT
243 # Select if arch init_task initializer is different to init/init_task.c
244 config ARCH_INIT_TASK
247 # Select if arch has its private alloc_task_struct() function
248 config ARCH_TASK_STRUCT_ALLOCATOR
251 # Select if arch has its private alloc_thread_stack() function
252 config ARCH_THREAD_STACK_ALLOCATOR
255 # Select if arch wants to size task_struct dynamically via arch_task_struct_size:
256 config ARCH_WANTS_DYNAMIC_TASK_STRUCT
259 config HAVE_REGS_AND_STACK_ACCESS_API
262 This symbol should be selected by an architecure if it supports
263 the API needed to access registers and stack entries from pt_regs,
264 declared in asm/ptrace.h
265 For example the kprobes-based event tracer needs this API.
270 The <linux/clk.h> calls support software clock gating and
271 thus are a key power management tool on many systems.
273 config HAVE_DMA_API_DEBUG
276 config HAVE_HW_BREAKPOINT
278 depends on PERF_EVENTS
280 config HAVE_MIXED_BREAKPOINTS_REGS
282 depends on HAVE_HW_BREAKPOINT
284 Depending on the arch implementation of hardware breakpoints,
285 some of them have separate registers for data and instruction
286 breakpoints addresses, others have mixed registers to store
287 them but define the access type in a control register.
288 Select this option if your arch implements breakpoints under the
291 config HAVE_USER_RETURN_NOTIFIER
294 config HAVE_PERF_EVENTS_NMI
297 System hardware can generate an NMI using the perf event
298 subsystem. Also has support for calculating CPU cycle events
299 to determine how many clock cycles in a given period.
301 config HAVE_HARDLOCKUP_DETECTOR_PERF
303 depends on HAVE_PERF_EVENTS_NMI
305 The arch chooses to use the generic perf-NMI-based hardlockup
306 detector. Must define HAVE_PERF_EVENTS_NMI.
308 config HAVE_NMI_WATCHDOG
312 The arch provides a low level NMI watchdog. It provides
313 asm/nmi.h, and defines its own arch_touch_nmi_watchdog().
315 config HAVE_HARDLOCKUP_DETECTOR_ARCH
317 select HAVE_NMI_WATCHDOG
319 The arch chooses to provide its own hardlockup detector, which is
320 a superset of the HAVE_NMI_WATCHDOG. It also conforms to config
321 interfaces and parameters provided by hardlockup detector subsystem.
323 config HAVE_PERF_REGS
326 Support selective register dumps for perf events. This includes
327 bit-mapping of each registers and a unique architecture id.
329 config HAVE_PERF_USER_STACK_DUMP
332 Support user stack dumps for perf event samples. This needs
333 access to the user stack pointer which is not unified across
336 config HAVE_ARCH_JUMP_LABEL
339 config HAVE_RCU_TABLE_FREE
342 config HAVE_RCU_TABLE_INVALIDATE
345 config ARCH_WANT_IRQS_OFF_ACTIVATE_MM
348 Temporary select until all architectures can be converted to have
349 irqs disabled over activate_mm. Architectures that do IPI based TLB
350 shootdowns should enable this.
352 config ARCH_HAVE_NMI_SAFE_CMPXCHG
355 config HAVE_ALIGNED_STRUCT_PAGE
358 This makes sure that struct pages are double word aligned and that
359 e.g. the SLUB allocator can perform double word atomic operations
360 on a struct page for better performance. However selecting this
361 might increase the size of a struct page by a word.
363 config HAVE_CMPXCHG_LOCAL
366 config HAVE_CMPXCHG_DOUBLE
369 config ARCH_WEAK_RELEASE_ACQUIRE
372 config ARCH_WANT_IPC_PARSE_VERSION
375 config ARCH_WANT_COMPAT_IPC_PARSE_VERSION
378 config ARCH_WANT_OLD_COMPAT_IPC
379 select ARCH_WANT_COMPAT_IPC_PARSE_VERSION
382 config HAVE_ARCH_SECCOMP_FILTER
385 An arch should select this symbol if it provides all of these things:
387 - syscall_get_arguments()
389 - syscall_set_return_value()
390 - SIGSYS siginfo_t support
391 - secure_computing is called from a ptrace_event()-safe context
392 - secure_computing return value is checked and a return value of -1
393 results in the system call being skipped immediately.
394 - seccomp syscall wired up
396 config SECCOMP_FILTER
398 depends on HAVE_ARCH_SECCOMP_FILTER && SECCOMP && NET
400 Enable tasks to build secure computing environments defined
401 in terms of Berkeley Packet Filter programs which implement
402 task-defined system call filtering polices.
404 See Documentation/prctl/seccomp_filter.txt for details.
406 config HAVE_GCC_PLUGINS
409 An arch should select this symbol if it supports building with
412 menuconfig GCC_PLUGINS
414 depends on HAVE_GCC_PLUGINS
415 depends on !COMPILE_TEST
417 GCC plugins are loadable modules that provide extra features to the
418 compiler. They are useful for runtime instrumentation and static analysis.
420 See Documentation/gcc-plugins.txt for details.
422 config GCC_PLUGIN_CYC_COMPLEXITY
423 bool "Compute the cyclomatic complexity of a function" if EXPERT
424 depends on GCC_PLUGINS
425 depends on !COMPILE_TEST
427 The complexity M of a function's control flow graph is defined as:
431 E = the number of edges
432 N = the number of nodes
433 P = the number of connected components (exit nodes).
435 Enabling this plugin reports the complexity to stderr during the
436 build. It mainly serves as a simple example of how to create a
437 gcc plugin for the kernel.
439 config GCC_PLUGIN_SANCOV
441 depends on GCC_PLUGINS
443 This plugin inserts a __sanitizer_cov_trace_pc() call at the start of
444 basic blocks. It supports all gcc versions with plugin support (from
445 gcc-4.5 on). It is based on the commit "Add fuzzing coverage support"
446 by Dmitry Vyukov <dvyukov@google.com>.
448 config GCC_PLUGIN_LATENT_ENTROPY
449 bool "Generate some entropy during boot and runtime"
450 depends on GCC_PLUGINS
452 By saying Y here the kernel will instrument some kernel code to
453 extract some entropy from both original and artificially created
454 program state. This will help especially embedded systems where
455 there is little 'natural' source of entropy normally. The cost
456 is some slowdown of the boot process (about 0.5%) and fork and
459 Note that entropy extracted this way is not cryptographically
462 This plugin was ported from grsecurity/PaX. More information at:
463 * https://grsecurity.net/
464 * https://pax.grsecurity.net/
466 config GCC_PLUGIN_STRUCTLEAK
467 bool "Force initialization of variables containing userspace addresses"
468 depends on GCC_PLUGINS
470 This plugin zero-initializes any structures containing a
471 __user attribute. This can prevent some classes of information
474 This plugin was ported from grsecurity/PaX. More information at:
475 * https://grsecurity.net/
476 * https://pax.grsecurity.net/
478 config GCC_PLUGIN_STRUCTLEAK_BYREF_ALL
479 bool "Force initialize all struct type variables passed by reference"
480 depends on GCC_PLUGIN_STRUCTLEAK
482 Zero initialize any struct type local variable that may be passed by
483 reference without having been initialized.
485 config GCC_PLUGIN_STRUCTLEAK_VERBOSE
486 bool "Report forcefully initialized variables"
487 depends on GCC_PLUGIN_STRUCTLEAK
488 depends on !COMPILE_TEST
490 This option will cause a warning to be printed each time the
491 structleak plugin finds a variable it thinks needs to be
492 initialized. Since not all existing initializers are detected
493 by the plugin, this can produce false positive warnings.
495 config GCC_PLUGIN_RANDSTRUCT
496 bool "Randomize layout of sensitive kernel structures"
497 depends on GCC_PLUGINS
498 select MODVERSIONS if MODULES
500 If you say Y here, the layouts of structures that are entirely
501 function pointers (and have not been manually annotated with
502 __no_randomize_layout), or structures that have been explicitly
503 marked with __randomize_layout, will be randomized at compile-time.
504 This can introduce the requirement of an additional information
505 exposure vulnerability for exploits targeting these structure
508 Enabling this feature will introduce some performance impact,
509 slightly increase memory usage, and prevent the use of forensic
510 tools like Volatility against the system (unless the kernel
511 source tree isn't cleaned after kernel installation).
513 The seed used for compilation is located at
514 scripts/gcc-plgins/randomize_layout_seed.h. It remains after
515 a make clean to allow for external modules to be compiled with
516 the existing seed and will be removed by a make mrproper or
519 Note that the implementation requires gcc 4.7 or newer.
521 This plugin was ported from grsecurity/PaX. More information at:
522 * https://grsecurity.net/
523 * https://pax.grsecurity.net/
525 config GCC_PLUGIN_RANDSTRUCT_PERFORMANCE
526 bool "Use cacheline-aware structure randomization"
527 depends on GCC_PLUGIN_RANDSTRUCT
528 depends on !COMPILE_TEST
530 If you say Y here, the RANDSTRUCT randomization will make a
531 best effort at restricting randomization to cacheline-sized
532 groups of elements. It will further not randomize bitfields
533 in structures. This reduces the performance hit of RANDSTRUCT
534 at the cost of weakened randomization.
536 config HAVE_CC_STACKPROTECTOR
539 An arch should select this symbol if:
540 - its compiler supports the -fstack-protector option
541 - it has implemented a stack canary (e.g. __stack_chk_guard)
543 config CC_STACKPROTECTOR
546 Set when a stack-protector mode is enabled, so that the build
547 can enable kernel-side support for the GCC feature.
550 prompt "Stack Protector buffer overflow detection"
551 depends on HAVE_CC_STACKPROTECTOR
552 default CC_STACKPROTECTOR_NONE
554 This option turns on the "stack-protector" GCC feature. This
555 feature puts, at the beginning of functions, a canary value on
556 the stack just before the return address, and validates
557 the value just before actually returning. Stack based buffer
558 overflows (that need to overwrite this return address) now also
559 overwrite the canary, which gets detected and the attack is then
560 neutralized via a kernel panic.
562 config CC_STACKPROTECTOR_NONE
565 Disable "stack-protector" GCC feature.
567 config CC_STACKPROTECTOR_REGULAR
569 select CC_STACKPROTECTOR
571 Functions will have the stack-protector canary logic added if they
572 have an 8-byte or larger character array on the stack.
574 This feature requires gcc version 4.2 or above, or a distribution
575 gcc with the feature backported ("-fstack-protector").
577 On an x86 "defconfig" build, this feature adds canary checks to
578 about 3% of all kernel functions, which increases kernel code size
581 config CC_STACKPROTECTOR_STRONG
583 select CC_STACKPROTECTOR
585 Functions will have the stack-protector canary logic added in any
586 of the following conditions:
588 - local variable's address used as part of the right hand side of an
589 assignment or function argument
590 - local variable is an array (or union containing an array),
591 regardless of array type or length
592 - uses register local variables
594 This feature requires gcc version 4.9 or above, or a distribution
595 gcc with the feature backported ("-fstack-protector-strong").
597 On an x86 "defconfig" build, this feature adds canary checks to
598 about 20% of all kernel functions, which increases the kernel code
606 Select this if the architecture wants to use thin archives
607 instead of ld -r to create the built-in.o files.
609 config LD_DEAD_CODE_DATA_ELIMINATION
612 Select this if the architecture wants to do dead code and
613 data elimination with the linker by compiling with
614 -ffunction-sections -fdata-sections and linking with
617 This requires that the arch annotates or otherwise protects
618 its external entry points from being discarded. Linker scripts
619 must also merge .text.*, .data.*, and .bss.* correctly into
620 output sections. Care must be taken not to pull in unrelated
621 sections (e.g., '.text.init'). Typically '.' in section names
622 is used to distinguish them from label names / C identifiers.
624 config HAVE_ARCH_WITHIN_STACK_FRAMES
627 An architecture should select this if it can walk the kernel stack
628 frames to determine if an object is part of either the arguments
629 or local variables (i.e. that it excludes saved return addresses,
630 and similar) by implementing an inline arch_within_stack_frames(),
631 which is used by CONFIG_HARDENED_USERCOPY.
633 config HAVE_CONTEXT_TRACKING
636 Provide kernel/user boundaries probes necessary for subsystems
637 that need it, such as userspace RCU extended quiescent state.
638 Syscalls need to be wrapped inside user_exit()-user_enter() through
639 the slow path using TIF_NOHZ flag. Exceptions handlers must be
640 wrapped as well. Irqs are already protected inside
641 rcu_irq_enter/rcu_irq_exit() but preemption or signal handling on
642 irq exit still need to be protected.
644 config HAVE_VIRT_CPU_ACCOUNTING
647 config ARCH_HAS_SCALED_CPUTIME
650 config HAVE_VIRT_CPU_ACCOUNTING_GEN
654 With VIRT_CPU_ACCOUNTING_GEN, cputime_t becomes 64-bit.
655 Before enabling this option, arch code must be audited
656 to ensure there are no races in concurrent read/write of
657 cputime_t. For example, reading/writing 64-bit cputime_t on
658 some 32-bit arches may require multiple accesses, so proper
659 locking is needed to protect against concurrent accesses.
662 config HAVE_IRQ_TIME_ACCOUNTING
665 Archs need to ensure they use a high enough resolution clock to
666 support irq time accounting and then call enable_sched_clock_irqtime().
668 config HAVE_ARCH_TRANSPARENT_HUGEPAGE
671 config HAVE_ARCH_TRANSPARENT_HUGEPAGE_PUD
674 config HAVE_ARCH_HUGE_VMAP
677 config HAVE_ARCH_SOFT_DIRTY
680 config HAVE_MOD_ARCH_SPECIFIC
683 The arch uses struct mod_arch_specific to store data. Many arches
684 just need a simple module loader without arch specific data - those
685 should not enable this.
687 config MODULES_USE_ELF_RELA
690 Modules only use ELF RELA relocations. Modules with ELF REL
691 relocations will give an error.
693 config MODULES_USE_ELF_REL
696 Modules only use ELF REL relocations. Modules with ELF RELA
697 relocations will give an error.
699 config HAVE_UNDERSCORE_SYMBOL_PREFIX
702 Some architectures generate an _ in front of C symbols; things like
703 module loading and assembly files need to know about this.
705 config HAVE_IRQ_EXIT_ON_IRQ_STACK
708 Architecture doesn't only execute the irq handler on the irq stack
709 but also irq_exit(). This way we can process softirqs on this irq
710 stack instead of switching to a new one when we call __do_softirq()
711 in the end of an hardirq.
712 This spares a stack switch and improves cache usage on softirq
715 config PGTABLE_LEVELS
719 config ARCH_HAS_ELF_RANDOMIZE
722 An architecture supports choosing randomized locations for
723 stack, mmap, brk, and ET_DYN. Defined functions:
725 - arch_randomize_brk()
727 config HAVE_ARCH_MMAP_RND_BITS
730 An arch should select this symbol if it supports setting a variable
731 number of bits for use in establishing the base address for mmap
732 allocations, has MMU enabled and provides values for both:
733 - ARCH_MMAP_RND_BITS_MIN
734 - ARCH_MMAP_RND_BITS_MAX
736 config HAVE_EXIT_THREAD
739 An architecture implements exit_thread.
741 config ARCH_MMAP_RND_BITS_MIN
744 config ARCH_MMAP_RND_BITS_MAX
747 config ARCH_MMAP_RND_BITS_DEFAULT
750 config ARCH_MMAP_RND_BITS
751 int "Number of bits to use for ASLR of mmap base address" if EXPERT
752 range ARCH_MMAP_RND_BITS_MIN ARCH_MMAP_RND_BITS_MAX
753 default ARCH_MMAP_RND_BITS_DEFAULT if ARCH_MMAP_RND_BITS_DEFAULT
754 default ARCH_MMAP_RND_BITS_MIN
755 depends on HAVE_ARCH_MMAP_RND_BITS
757 This value can be used to select the number of bits to use to
758 determine the random offset to the base address of vma regions
759 resulting from mmap allocations. This value will be bounded
760 by the architecture's minimum and maximum supported values.
762 This value can be changed after boot using the
763 /proc/sys/vm/mmap_rnd_bits tunable
765 config HAVE_ARCH_MMAP_RND_COMPAT_BITS
768 An arch should select this symbol if it supports running applications
769 in compatibility mode, supports setting a variable number of bits for
770 use in establishing the base address for mmap allocations, has MMU
771 enabled and provides values for both:
772 - ARCH_MMAP_RND_COMPAT_BITS_MIN
773 - ARCH_MMAP_RND_COMPAT_BITS_MAX
775 config ARCH_MMAP_RND_COMPAT_BITS_MIN
778 config ARCH_MMAP_RND_COMPAT_BITS_MAX
781 config ARCH_MMAP_RND_COMPAT_BITS_DEFAULT
784 config ARCH_MMAP_RND_COMPAT_BITS
785 int "Number of bits to use for ASLR of mmap base address for compatible applications" if EXPERT
786 range ARCH_MMAP_RND_COMPAT_BITS_MIN ARCH_MMAP_RND_COMPAT_BITS_MAX
787 default ARCH_MMAP_RND_COMPAT_BITS_DEFAULT if ARCH_MMAP_RND_COMPAT_BITS_DEFAULT
788 default ARCH_MMAP_RND_COMPAT_BITS_MIN
789 depends on HAVE_ARCH_MMAP_RND_COMPAT_BITS
791 This value can be used to select the number of bits to use to
792 determine the random offset to the base address of vma regions
793 resulting from mmap allocations for compatible applications This
794 value will be bounded by the architecture's minimum and maximum
797 This value can be changed after boot using the
798 /proc/sys/vm/mmap_rnd_compat_bits tunable
800 config HAVE_ARCH_COMPAT_MMAP_BASES
803 This allows 64bit applications to invoke 32-bit mmap() syscall
804 and vice-versa 32-bit applications to call 64-bit mmap().
805 Required for applications doing different bitness syscalls.
807 config HAVE_COPY_THREAD_TLS
810 Architecture provides copy_thread_tls to accept tls argument via
811 normal C parameter passing, rather than extracting the syscall
812 argument from pt_regs.
814 config HAVE_STACK_VALIDATION
817 Architecture supports the 'objtool check' host tool command, which
818 performs compile-time stack metadata validation.
820 config HAVE_RELIABLE_STACKTRACE
823 Architecture has a save_stack_trace_tsk_reliable() function which
824 only returns a stack trace if it can guarantee the trace is reliable.
826 config HAVE_ARCH_HASH
830 If this is set, the architecture provides an <asm/hash.h>
831 file which provides platform-specific implementations of some
832 functions in <linux/hash.h> or fs/namei.c.
840 config CLONE_BACKWARDS
843 Architecture has tls passed as the 4th argument of clone(2),
846 config CLONE_BACKWARDS2
849 Architecture has the first two arguments of clone(2) swapped.
851 config CLONE_BACKWARDS3
854 Architecture has tls passed as the 3rd argument of clone(2),
857 config ODD_RT_SIGACTION
860 Architecture has unusual rt_sigaction(2) arguments
862 config OLD_SIGSUSPEND
865 Architecture has old sigsuspend(2) syscall, of one-argument variety
867 config OLD_SIGSUSPEND3
870 Even weirder antique ABI - three-argument sigsuspend(2)
875 Architecture has old sigaction(2) syscall. Nope, not the same
876 as OLD_SIGSUSPEND | OLD_SIGSUSPEND3 - alpha has sigsuspend(2),
877 but fairly different variant of sigaction(2), thanks to OSF/1
880 config COMPAT_OLD_SIGACTION
883 config ARCH_NO_COHERENT_DMA_MMAP
886 config CPU_NO_EFFICIENT_FFS
889 config HAVE_ARCH_VMAP_STACK
892 An arch should select this symbol if it can support kernel stacks
893 in vmalloc space. This means:
895 - vmalloc space must be large enough to hold many kernel stacks.
896 This may rule out many 32-bit architectures.
898 - Stacks in vmalloc space need to work reliably. For example, if
899 vmap page tables are created on demand, either this mechanism
900 needs to work while the stack points to a virtual address with
901 unpopulated page tables or arch code (switch_to() and switch_mm(),
902 most likely) needs to ensure that the stack's page table entries
903 are populated before running on a possibly unpopulated stack.
905 - If the stack overflows into a guard page, something reasonable
906 should happen. The definition of "reasonable" is flexible, but
907 instantly rebooting without logging anything would be unfriendly.
911 bool "Use a virtually-mapped stack"
912 depends on HAVE_ARCH_VMAP_STACK && !KASAN
914 Enable this if you want the use virtually-mapped kernel stacks
915 with guard pages. This causes kernel stack overflows to be
916 caught immediately rather than causing difficult-to-diagnose
919 This is presently incompatible with KASAN because KASAN expects
920 the stack to map directly to the KASAN shadow map using a formula
921 that is incorrect if the stack is in vmalloc space.
923 config ARCH_OPTIONAL_KERNEL_RWX
926 config ARCH_OPTIONAL_KERNEL_RWX_DEFAULT
929 config ARCH_HAS_STRICT_KERNEL_RWX
932 config STRICT_KERNEL_RWX
933 bool "Make kernel text and rodata read-only" if ARCH_OPTIONAL_KERNEL_RWX
934 depends on ARCH_HAS_STRICT_KERNEL_RWX
935 default !ARCH_OPTIONAL_KERNEL_RWX || ARCH_OPTIONAL_KERNEL_RWX_DEFAULT
937 If this is set, kernel text and rodata memory will be made read-only,
938 and non-text memory will be made non-executable. This provides
939 protection against certain security exploits (e.g. executing the heap
942 These features are considered standard security practice these days.
943 You should say Y here in almost all cases.
945 config ARCH_HAS_STRICT_MODULE_RWX
948 config STRICT_MODULE_RWX
949 bool "Set loadable kernel module data as NX and text as RO" if ARCH_OPTIONAL_KERNEL_RWX
950 depends on ARCH_HAS_STRICT_MODULE_RWX && MODULES
951 default !ARCH_OPTIONAL_KERNEL_RWX || ARCH_OPTIONAL_KERNEL_RWX_DEFAULT
953 If this is set, module text and rodata memory will be made read-only,
954 and non-text memory will be made non-executable. This provides
955 protection against certain security exploits (e.g. writing to text)
957 config ARCH_HAS_REFCOUNT
960 An architecture selects this when it has implemented refcount_t
961 using open coded assembly primitives that provide an optimized
962 refcount_t implementation, possibly at the expense of some full
963 refcount state checks of CONFIG_REFCOUNT_FULL=y.
965 The refcount overflow check behavior, however, must be retained.
966 Catching overflows is the primary security concern for protecting
967 against bugs in reference counts.
970 bool "Perform full reference count validation at the expense of speed"
972 Enabling this switches the refcounting infrastructure from a fast
973 unchecked atomic_t implementation to a fully state checked
974 implementation, which can be (slightly) slower but provides protections
975 against various use-after-free conditions that can be used in
976 security flaw exploits.
978 config HAVE_ARCH_COMPILER_H
981 An architecture can select this if it provides an
982 asm/compiler.h header that should be included after
983 linux/compiler-*.h in order to override macro definitions that those
984 headers generally provide.
986 config ARCH_USE_MEMREMAP_PROT
989 source "kernel/gcov/Kconfig"