2 # General architecture dependent options
16 tristate "OProfile system profiling"
18 depends on HAVE_OPROFILE
20 select RING_BUFFER_ALLOW_SWAP
22 OProfile is a profiling system capable of profiling the
23 whole system, include the kernel, kernel modules, libraries,
28 config OPROFILE_EVENT_MULTIPLEX
29 bool "OProfile multiplexing support (EXPERIMENTAL)"
31 depends on OPROFILE && X86
33 The number of hardware counters is limited. The multiplexing
34 feature enables OProfile to gather more events than counters
35 are provided by the hardware. This is realized by switching
36 between events at a user specified time interval.
43 config OPROFILE_NMI_TIMER
45 depends on PERF_EVENTS && HAVE_PERF_EVENTS_NMI && !PPC64
50 depends on HAVE_KPROBES
53 Kprobes allows you to trap at almost any kernel address and
54 execute a callback function. register_kprobe() establishes
55 a probepoint and specifies the callback. Kprobes is useful
56 for kernel debugging, non-intrusive instrumentation and testing.
60 bool "Optimize very unlikely/likely branches"
61 depends on HAVE_ARCH_JUMP_LABEL
63 This option enables a transparent branch optimization that
64 makes certain almost-always-true or almost-always-false branch
65 conditions even cheaper to execute within the kernel.
67 Certain performance-sensitive kernel code, such as trace points,
68 scheduler functionality, networking code and KVM have such
69 branches and include support for this optimization technique.
71 If it is detected that the compiler has support for "asm goto",
72 the kernel will compile such branches with just a nop
73 instruction. When the condition flag is toggled to true, the
74 nop will be converted to a jump instruction to execute the
75 conditional block of instructions.
77 This technique lowers overhead and stress on the branch prediction
78 of the processor and generally makes the kernel faster. The update
79 of the condition is slower, but those are always very rare.
81 ( On 32-bit x86, the necessary options added to the compiler
82 flags may increase the size of the kernel slightly. )
84 config STATIC_KEYS_SELFTEST
85 bool "Static key selftest"
88 Boot time self-test of the branch patching code.
92 depends on KPROBES && HAVE_OPTPROBES
95 config KPROBES_ON_FTRACE
97 depends on KPROBES && HAVE_KPROBES_ON_FTRACE
98 depends on DYNAMIC_FTRACE_WITH_REGS
100 If function tracer is enabled and the arch supports full
101 passing of pt_regs to function tracing, then kprobes can
102 optimize on top of function tracing.
106 depends on ARCH_SUPPORTS_UPROBES
108 Uprobes is the user-space counterpart to kprobes: they
109 enable instrumentation applications (such as 'perf probe')
110 to establish unintrusive probes in user-space binaries and
111 libraries, by executing handler functions when the probes
112 are hit by user-space applications.
114 ( These probes come in the form of single-byte breakpoints,
115 managed by the kernel and kept transparent to the probed
118 config HAVE_64BIT_ALIGNED_ACCESS
119 def_bool 64BIT && !HAVE_EFFICIENT_UNALIGNED_ACCESS
121 Some architectures require 64 bit accesses to be 64 bit
122 aligned, which also requires structs containing 64 bit values
123 to be 64 bit aligned too. This includes some 32 bit
124 architectures which can do 64 bit accesses, as well as 64 bit
125 architectures without unaligned access.
127 This symbol should be selected by an architecture if 64 bit
128 accesses are required to be 64 bit aligned in this way even
129 though it is not a 64 bit architecture.
131 See Documentation/unaligned-memory-access.txt for more
132 information on the topic of unaligned memory accesses.
134 config HAVE_EFFICIENT_UNALIGNED_ACCESS
137 Some architectures are unable to perform unaligned accesses
138 without the use of get_unaligned/put_unaligned. Others are
139 unable to perform such accesses efficiently (e.g. trap on
140 unaligned access and require fixing it up in the exception
143 This symbol should be selected by an architecture if it can
144 perform unaligned accesses efficiently to allow different
145 code paths to be selected for these cases. Some network
146 drivers, for example, could opt to not fix up alignment
147 problems with received packets if doing so would not help
150 See Documentation/unaligned-memory-access.txt for more
151 information on the topic of unaligned memory accesses.
153 config ARCH_USE_BUILTIN_BSWAP
156 Modern versions of GCC (since 4.4) have builtin functions
157 for handling byte-swapping. Using these, instead of the old
158 inline assembler that the architecture code provides in the
159 __arch_bswapXX() macros, allows the compiler to see what's
160 happening and offers more opportunity for optimisation. In
161 particular, the compiler will be able to combine the byteswap
162 with a nearby load or store and use load-and-swap or
163 store-and-swap instructions if the architecture has them. It
164 should almost *never* result in code which is worse than the
165 hand-coded assembler in <asm/swab.h>. But just in case it
166 does, the use of the builtins is optional.
168 Any architecture with load-and-swap or store-and-swap
169 instructions should set this. And it shouldn't hurt to set it
170 on architectures that don't have such instructions.
174 depends on KPROBES && HAVE_KRETPROBES
176 config USER_RETURN_NOTIFIER
178 depends on HAVE_USER_RETURN_NOTIFIER
180 Provide a kernel-internal notification when a cpu is about to
183 config HAVE_IOREMAP_PROT
189 config HAVE_KRETPROBES
192 config HAVE_OPTPROBES
195 config HAVE_KPROBES_ON_FTRACE
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 # Select if arch has all set_memory_ro/rw/x/nx() functions in asm/cacheflush.h
227 config ARCH_HAS_SET_MEMORY
230 # Select if arch init_task initializer is different to init/init_task.c
231 config ARCH_INIT_TASK
234 # Select if arch has its private alloc_task_struct() function
235 config ARCH_TASK_STRUCT_ALLOCATOR
238 # Select if arch has its private alloc_thread_stack() function
239 config ARCH_THREAD_STACK_ALLOCATOR
242 # Select if arch wants to size task_struct dynamically via arch_task_struct_size:
243 config ARCH_WANTS_DYNAMIC_TASK_STRUCT
246 config HAVE_REGS_AND_STACK_ACCESS_API
249 This symbol should be selected by an architecure if it supports
250 the API needed to access registers and stack entries from pt_regs,
251 declared in asm/ptrace.h
252 For example the kprobes-based event tracer needs this API.
257 The <linux/clk.h> calls support software clock gating and
258 thus are a key power management tool on many systems.
260 config HAVE_DMA_API_DEBUG
263 config HAVE_HW_BREAKPOINT
265 depends on PERF_EVENTS
267 config HAVE_MIXED_BREAKPOINTS_REGS
269 depends on HAVE_HW_BREAKPOINT
271 Depending on the arch implementation of hardware breakpoints,
272 some of them have separate registers for data and instruction
273 breakpoints addresses, others have mixed registers to store
274 them but define the access type in a control register.
275 Select this option if your arch implements breakpoints under the
278 config HAVE_USER_RETURN_NOTIFIER
281 config HAVE_PERF_EVENTS_NMI
284 System hardware can generate an NMI using the perf event
285 subsystem. Also has support for calculating CPU cycle events
286 to determine how many clock cycles in a given period.
288 config HAVE_HARDLOCKUP_DETECTOR_PERF
290 depends on HAVE_PERF_EVENTS_NMI
292 The arch chooses to use the generic perf-NMI-based hardlockup
293 detector. Must define HAVE_PERF_EVENTS_NMI.
295 config HAVE_NMI_WATCHDOG
299 The arch provides a low level NMI watchdog. It provides
300 asm/nmi.h, and defines its own arch_touch_nmi_watchdog().
302 config HAVE_HARDLOCKUP_DETECTOR_ARCH
304 select HAVE_NMI_WATCHDOG
306 The arch chooses to provide its own hardlockup detector, which is
307 a superset of the HAVE_NMI_WATCHDOG. It also conforms to config
308 interfaces and parameters provided by hardlockup detector subsystem.
310 config HAVE_PERF_REGS
313 Support selective register dumps for perf events. This includes
314 bit-mapping of each registers and a unique architecture id.
316 config HAVE_PERF_USER_STACK_DUMP
319 Support user stack dumps for perf event samples. This needs
320 access to the user stack pointer which is not unified across
323 config HAVE_ARCH_JUMP_LABEL
326 config HAVE_RCU_TABLE_FREE
329 config ARCH_HAVE_NMI_SAFE_CMPXCHG
332 config HAVE_ALIGNED_STRUCT_PAGE
335 This makes sure that struct pages are double word aligned and that
336 e.g. the SLUB allocator can perform double word atomic operations
337 on a struct page for better performance. However selecting this
338 might increase the size of a struct page by a word.
340 config HAVE_CMPXCHG_LOCAL
343 config HAVE_CMPXCHG_DOUBLE
346 config ARCH_WEAK_RELEASE_ACQUIRE
349 config ARCH_WANT_IPC_PARSE_VERSION
352 config ARCH_WANT_COMPAT_IPC_PARSE_VERSION
355 config ARCH_WANT_OLD_COMPAT_IPC
356 select ARCH_WANT_COMPAT_IPC_PARSE_VERSION
359 config HAVE_ARCH_SECCOMP_FILTER
362 An arch should select this symbol if it provides all of these things:
364 - syscall_get_arguments()
366 - syscall_set_return_value()
367 - SIGSYS siginfo_t support
368 - secure_computing is called from a ptrace_event()-safe context
369 - secure_computing return value is checked and a return value of -1
370 results in the system call being skipped immediately.
371 - seccomp syscall wired up
373 config SECCOMP_FILTER
375 depends on HAVE_ARCH_SECCOMP_FILTER && SECCOMP && NET
377 Enable tasks to build secure computing environments defined
378 in terms of Berkeley Packet Filter programs which implement
379 task-defined system call filtering polices.
381 See Documentation/prctl/seccomp_filter.txt for details.
383 config HAVE_GCC_PLUGINS
386 An arch should select this symbol if it supports building with
389 menuconfig GCC_PLUGINS
391 depends on HAVE_GCC_PLUGINS
392 depends on !COMPILE_TEST
394 GCC plugins are loadable modules that provide extra features to the
395 compiler. They are useful for runtime instrumentation and static analysis.
397 See Documentation/gcc-plugins.txt for details.
399 config GCC_PLUGIN_CYC_COMPLEXITY
400 bool "Compute the cyclomatic complexity of a function" if EXPERT
401 depends on GCC_PLUGINS
402 depends on !COMPILE_TEST
404 The complexity M of a function's control flow graph is defined as:
408 E = the number of edges
409 N = the number of nodes
410 P = the number of connected components (exit nodes).
412 Enabling this plugin reports the complexity to stderr during the
413 build. It mainly serves as a simple example of how to create a
414 gcc plugin for the kernel.
416 config GCC_PLUGIN_SANCOV
418 depends on GCC_PLUGINS
420 This plugin inserts a __sanitizer_cov_trace_pc() call at the start of
421 basic blocks. It supports all gcc versions with plugin support (from
422 gcc-4.5 on). It is based on the commit "Add fuzzing coverage support"
423 by Dmitry Vyukov <dvyukov@google.com>.
425 config GCC_PLUGIN_LATENT_ENTROPY
426 bool "Generate some entropy during boot and runtime"
427 depends on GCC_PLUGINS
429 By saying Y here the kernel will instrument some kernel code to
430 extract some entropy from both original and artificially created
431 program state. This will help especially embedded systems where
432 there is little 'natural' source of entropy normally. The cost
433 is some slowdown of the boot process (about 0.5%) and fork and
436 Note that entropy extracted this way is not cryptographically
439 This plugin was ported from grsecurity/PaX. More information at:
440 * https://grsecurity.net/
441 * https://pax.grsecurity.net/
443 config GCC_PLUGIN_STRUCTLEAK
444 bool "Force initialization of variables containing userspace addresses"
445 depends on GCC_PLUGINS
447 This plugin zero-initializes any structures containing a
448 __user attribute. This can prevent some classes of information
451 This plugin was ported from grsecurity/PaX. More information at:
452 * https://grsecurity.net/
453 * https://pax.grsecurity.net/
455 config GCC_PLUGIN_STRUCTLEAK_VERBOSE
456 bool "Report forcefully initialized variables"
457 depends on GCC_PLUGIN_STRUCTLEAK
458 depends on !COMPILE_TEST
460 This option will cause a warning to be printed each time the
461 structleak plugin finds a variable it thinks needs to be
462 initialized. Since not all existing initializers are detected
463 by the plugin, this can produce false positive warnings.
465 config GCC_PLUGIN_RANDSTRUCT
466 bool "Randomize layout of sensitive kernel structures"
467 depends on GCC_PLUGINS
468 select MODVERSIONS if MODULES
470 If you say Y here, the layouts of structures explicitly
471 marked by __randomize_layout will be randomized at
472 compile-time. This can introduce the requirement of an
473 additional information exposure vulnerability for exploits
474 targeting these structure types.
476 Enabling this feature will introduce some performance impact,
477 slightly increase memory usage, and prevent the use of forensic
478 tools like Volatility against the system (unless the kernel
479 source tree isn't cleaned after kernel installation).
481 The seed used for compilation is located at
482 scripts/gcc-plgins/randomize_layout_seed.h. It remains after
483 a make clean to allow for external modules to be compiled with
484 the existing seed and will be removed by a make mrproper or
487 Note that the implementation requires gcc 4.7 or newer.
489 This plugin was ported from grsecurity/PaX. More information at:
490 * https://grsecurity.net/
491 * https://pax.grsecurity.net/
493 config GCC_PLUGIN_RANDSTRUCT_PERFORMANCE
494 bool "Use cacheline-aware structure randomization"
495 depends on GCC_PLUGIN_RANDSTRUCT
496 depends on !COMPILE_TEST
498 If you say Y here, the RANDSTRUCT randomization will make a
499 best effort at restricting randomization to cacheline-sized
500 groups of elements. It will further not randomize bitfields
501 in structures. This reduces the performance hit of RANDSTRUCT
502 at the cost of weakened randomization.
504 config HAVE_CC_STACKPROTECTOR
507 An arch should select this symbol if:
508 - its compiler supports the -fstack-protector option
509 - it has implemented a stack canary (e.g. __stack_chk_guard)
511 config CC_STACKPROTECTOR
514 Set when a stack-protector mode is enabled, so that the build
515 can enable kernel-side support for the GCC feature.
518 prompt "Stack Protector buffer overflow detection"
519 depends on HAVE_CC_STACKPROTECTOR
520 default CC_STACKPROTECTOR_NONE
522 This option turns on the "stack-protector" GCC feature. This
523 feature puts, at the beginning of functions, a canary value on
524 the stack just before the return address, and validates
525 the value just before actually returning. Stack based buffer
526 overflows (that need to overwrite this return address) now also
527 overwrite the canary, which gets detected and the attack is then
528 neutralized via a kernel panic.
530 config CC_STACKPROTECTOR_NONE
533 Disable "stack-protector" GCC feature.
535 config CC_STACKPROTECTOR_REGULAR
537 select CC_STACKPROTECTOR
539 Functions will have the stack-protector canary logic added if they
540 have an 8-byte or larger character array on the stack.
542 This feature requires gcc version 4.2 or above, or a distribution
543 gcc with the feature backported ("-fstack-protector").
545 On an x86 "defconfig" build, this feature adds canary checks to
546 about 3% of all kernel functions, which increases kernel code size
549 config CC_STACKPROTECTOR_STRONG
551 select CC_STACKPROTECTOR
553 Functions will have the stack-protector canary logic added in any
554 of the following conditions:
556 - local variable's address used as part of the right hand side of an
557 assignment or function argument
558 - local variable is an array (or union containing an array),
559 regardless of array type or length
560 - uses register local variables
562 This feature requires gcc version 4.9 or above, or a distribution
563 gcc with the feature backported ("-fstack-protector-strong").
565 On an x86 "defconfig" build, this feature adds canary checks to
566 about 20% of all kernel functions, which increases the kernel code
574 Select this if the architecture wants to use thin archives
575 instead of ld -r to create the built-in.o files.
577 config LD_DEAD_CODE_DATA_ELIMINATION
580 Select this if the architecture wants to do dead code and
581 data elimination with the linker by compiling with
582 -ffunction-sections -fdata-sections and linking with
585 This requires that the arch annotates or otherwise protects
586 its external entry points from being discarded. Linker scripts
587 must also merge .text.*, .data.*, and .bss.* correctly into
588 output sections. Care must be taken not to pull in unrelated
589 sections (e.g., '.text.init'). Typically '.' in section names
590 is used to distinguish them from label names / C identifiers.
592 config HAVE_ARCH_WITHIN_STACK_FRAMES
595 An architecture should select this if it can walk the kernel stack
596 frames to determine if an object is part of either the arguments
597 or local variables (i.e. that it excludes saved return addresses,
598 and similar) by implementing an inline arch_within_stack_frames(),
599 which is used by CONFIG_HARDENED_USERCOPY.
601 config HAVE_CONTEXT_TRACKING
604 Provide kernel/user boundaries probes necessary for subsystems
605 that need it, such as userspace RCU extended quiescent state.
606 Syscalls need to be wrapped inside user_exit()-user_enter() through
607 the slow path using TIF_NOHZ flag. Exceptions handlers must be
608 wrapped as well. Irqs are already protected inside
609 rcu_irq_enter/rcu_irq_exit() but preemption or signal handling on
610 irq exit still need to be protected.
612 config HAVE_VIRT_CPU_ACCOUNTING
615 config ARCH_HAS_SCALED_CPUTIME
618 config HAVE_VIRT_CPU_ACCOUNTING_GEN
622 With VIRT_CPU_ACCOUNTING_GEN, cputime_t becomes 64-bit.
623 Before enabling this option, arch code must be audited
624 to ensure there are no races in concurrent read/write of
625 cputime_t. For example, reading/writing 64-bit cputime_t on
626 some 32-bit arches may require multiple accesses, so proper
627 locking is needed to protect against concurrent accesses.
630 config HAVE_IRQ_TIME_ACCOUNTING
633 Archs need to ensure they use a high enough resolution clock to
634 support irq time accounting and then call enable_sched_clock_irqtime().
636 config HAVE_ARCH_TRANSPARENT_HUGEPAGE
639 config HAVE_ARCH_TRANSPARENT_HUGEPAGE_PUD
642 config HAVE_ARCH_HUGE_VMAP
645 config HAVE_ARCH_SOFT_DIRTY
648 config HAVE_MOD_ARCH_SPECIFIC
651 The arch uses struct mod_arch_specific to store data. Many arches
652 just need a simple module loader without arch specific data - those
653 should not enable this.
655 config MODULES_USE_ELF_RELA
658 Modules only use ELF RELA relocations. Modules with ELF REL
659 relocations will give an error.
661 config MODULES_USE_ELF_REL
664 Modules only use ELF REL relocations. Modules with ELF RELA
665 relocations will give an error.
667 config HAVE_UNDERSCORE_SYMBOL_PREFIX
670 Some architectures generate an _ in front of C symbols; things like
671 module loading and assembly files need to know about this.
673 config HAVE_IRQ_EXIT_ON_IRQ_STACK
676 Architecture doesn't only execute the irq handler on the irq stack
677 but also irq_exit(). This way we can process softirqs on this irq
678 stack instead of switching to a new one when we call __do_softirq()
679 in the end of an hardirq.
680 This spares a stack switch and improves cache usage on softirq
683 config PGTABLE_LEVELS
687 config ARCH_HAS_ELF_RANDOMIZE
690 An architecture supports choosing randomized locations for
691 stack, mmap, brk, and ET_DYN. Defined functions:
693 - arch_randomize_brk()
695 config HAVE_ARCH_MMAP_RND_BITS
698 An arch should select this symbol if it supports setting a variable
699 number of bits for use in establishing the base address for mmap
700 allocations, has MMU enabled and provides values for both:
701 - ARCH_MMAP_RND_BITS_MIN
702 - ARCH_MMAP_RND_BITS_MAX
704 config HAVE_EXIT_THREAD
707 An architecture implements exit_thread.
709 config ARCH_MMAP_RND_BITS_MIN
712 config ARCH_MMAP_RND_BITS_MAX
715 config ARCH_MMAP_RND_BITS_DEFAULT
718 config ARCH_MMAP_RND_BITS
719 int "Number of bits to use for ASLR of mmap base address" if EXPERT
720 range ARCH_MMAP_RND_BITS_MIN ARCH_MMAP_RND_BITS_MAX
721 default ARCH_MMAP_RND_BITS_DEFAULT if ARCH_MMAP_RND_BITS_DEFAULT
722 default ARCH_MMAP_RND_BITS_MIN
723 depends on HAVE_ARCH_MMAP_RND_BITS
725 This value can be used to select the number of bits to use to
726 determine the random offset to the base address of vma regions
727 resulting from mmap allocations. This value will be bounded
728 by the architecture's minimum and maximum supported values.
730 This value can be changed after boot using the
731 /proc/sys/vm/mmap_rnd_bits tunable
733 config HAVE_ARCH_MMAP_RND_COMPAT_BITS
736 An arch should select this symbol if it supports running applications
737 in compatibility mode, supports setting a variable number of bits for
738 use in establishing the base address for mmap allocations, has MMU
739 enabled and provides values for both:
740 - ARCH_MMAP_RND_COMPAT_BITS_MIN
741 - ARCH_MMAP_RND_COMPAT_BITS_MAX
743 config ARCH_MMAP_RND_COMPAT_BITS_MIN
746 config ARCH_MMAP_RND_COMPAT_BITS_MAX
749 config ARCH_MMAP_RND_COMPAT_BITS_DEFAULT
752 config ARCH_MMAP_RND_COMPAT_BITS
753 int "Number of bits to use for ASLR of mmap base address for compatible applications" if EXPERT
754 range ARCH_MMAP_RND_COMPAT_BITS_MIN ARCH_MMAP_RND_COMPAT_BITS_MAX
755 default ARCH_MMAP_RND_COMPAT_BITS_DEFAULT if ARCH_MMAP_RND_COMPAT_BITS_DEFAULT
756 default ARCH_MMAP_RND_COMPAT_BITS_MIN
757 depends on HAVE_ARCH_MMAP_RND_COMPAT_BITS
759 This value can be used to select the number of bits to use to
760 determine the random offset to the base address of vma regions
761 resulting from mmap allocations for compatible applications This
762 value will be bounded by the architecture's minimum and maximum
765 This value can be changed after boot using the
766 /proc/sys/vm/mmap_rnd_compat_bits tunable
768 config HAVE_ARCH_COMPAT_MMAP_BASES
771 This allows 64bit applications to invoke 32-bit mmap() syscall
772 and vice-versa 32-bit applications to call 64-bit mmap().
773 Required for applications doing different bitness syscalls.
775 config HAVE_COPY_THREAD_TLS
778 Architecture provides copy_thread_tls to accept tls argument via
779 normal C parameter passing, rather than extracting the syscall
780 argument from pt_regs.
782 config HAVE_STACK_VALIDATION
785 Architecture supports the 'objtool check' host tool command, which
786 performs compile-time stack metadata validation.
788 config HAVE_RELIABLE_STACKTRACE
791 Architecture has a save_stack_trace_tsk_reliable() function which
792 only returns a stack trace if it can guarantee the trace is reliable.
794 config HAVE_ARCH_HASH
798 If this is set, the architecture provides an <asm/hash.h>
799 file which provides platform-specific implementations of some
800 functions in <linux/hash.h> or fs/namei.c.
808 config CLONE_BACKWARDS
811 Architecture has tls passed as the 4th argument of clone(2),
814 config CLONE_BACKWARDS2
817 Architecture has the first two arguments of clone(2) swapped.
819 config CLONE_BACKWARDS3
822 Architecture has tls passed as the 3rd argument of clone(2),
825 config ODD_RT_SIGACTION
828 Architecture has unusual rt_sigaction(2) arguments
830 config OLD_SIGSUSPEND
833 Architecture has old sigsuspend(2) syscall, of one-argument variety
835 config OLD_SIGSUSPEND3
838 Even weirder antique ABI - three-argument sigsuspend(2)
843 Architecture has old sigaction(2) syscall. Nope, not the same
844 as OLD_SIGSUSPEND | OLD_SIGSUSPEND3 - alpha has sigsuspend(2),
845 but fairly different variant of sigaction(2), thanks to OSF/1
848 config COMPAT_OLD_SIGACTION
851 config ARCH_NO_COHERENT_DMA_MMAP
854 config CPU_NO_EFFICIENT_FFS
857 config HAVE_ARCH_VMAP_STACK
860 An arch should select this symbol if it can support kernel stacks
861 in vmalloc space. This means:
863 - vmalloc space must be large enough to hold many kernel stacks.
864 This may rule out many 32-bit architectures.
866 - Stacks in vmalloc space need to work reliably. For example, if
867 vmap page tables are created on demand, either this mechanism
868 needs to work while the stack points to a virtual address with
869 unpopulated page tables or arch code (switch_to() and switch_mm(),
870 most likely) needs to ensure that the stack's page table entries
871 are populated before running on a possibly unpopulated stack.
873 - If the stack overflows into a guard page, something reasonable
874 should happen. The definition of "reasonable" is flexible, but
875 instantly rebooting without logging anything would be unfriendly.
879 bool "Use a virtually-mapped stack"
880 depends on HAVE_ARCH_VMAP_STACK && !KASAN
882 Enable this if you want the use virtually-mapped kernel stacks
883 with guard pages. This causes kernel stack overflows to be
884 caught immediately rather than causing difficult-to-diagnose
887 This is presently incompatible with KASAN because KASAN expects
888 the stack to map directly to the KASAN shadow map using a formula
889 that is incorrect if the stack is in vmalloc space.
891 config ARCH_OPTIONAL_KERNEL_RWX
894 config ARCH_OPTIONAL_KERNEL_RWX_DEFAULT
897 config ARCH_HAS_STRICT_KERNEL_RWX
900 config STRICT_KERNEL_RWX
901 bool "Make kernel text and rodata read-only" if ARCH_OPTIONAL_KERNEL_RWX
902 depends on ARCH_HAS_STRICT_KERNEL_RWX
903 default !ARCH_OPTIONAL_KERNEL_RWX || ARCH_OPTIONAL_KERNEL_RWX_DEFAULT
905 If this is set, kernel text and rodata memory will be made read-only,
906 and non-text memory will be made non-executable. This provides
907 protection against certain security exploits (e.g. executing the heap
910 These features are considered standard security practice these days.
911 You should say Y here in almost all cases.
913 config ARCH_HAS_STRICT_MODULE_RWX
916 config STRICT_MODULE_RWX
917 bool "Set loadable kernel module data as NX and text as RO" if ARCH_OPTIONAL_KERNEL_RWX
918 depends on ARCH_HAS_STRICT_MODULE_RWX && MODULES
919 default !ARCH_OPTIONAL_KERNEL_RWX || ARCH_OPTIONAL_KERNEL_RWX_DEFAULT
921 If this is set, module text and rodata memory will be made read-only,
922 and non-text memory will be made non-executable. This provides
923 protection against certain security exploits (e.g. writing to text)
925 config ARCH_WANT_RELAX_ORDER
929 bool "Perform full reference count validation at the expense of speed"
931 Enabling this switches the refcounting infrastructure from a fast
932 unchecked atomic_t implementation to a fully state checked
933 implementation, which can be (slightly) slower but provides protections
934 against various use-after-free conditions that can be used in
935 security flaw exploits.
937 source "kernel/gcov/Kconfig"