| blob | 400b9e1b2f275d2f253a54087c137bedf0a491ea |
1 # SPDX-License-Identifier: GPL-2.0
2 #
3 # General architecture dependent options
4 #
6 config CRASH_CORE
7 bool
9 config KEXEC_CORE
10 select CRASH_CORE
11 bool
13 config HAVE_IMA_KEXEC
14 bool
16 config OPROFILE
17 tristate "OProfile system profiling"
18 depends on PROFILING
19 depends on HAVE_OPROFILE
20 select RING_BUFFER
21 select RING_BUFFER_ALLOW_SWAP
22 help
23 OProfile is a profiling system capable of profiling the
24 whole system, include the kernel, kernel modules, libraries,
25 and applications.
27 If unsure, say N.
29 config OPROFILE_EVENT_MULTIPLEX
30 bool "OProfile multiplexing support (EXPERIMENTAL)"
31 default n
32 depends on OPROFILE && X86
33 help
34 The number of hardware counters is limited. The multiplexing
35 feature enables OProfile to gather more events than counters
36 are provided by the hardware. This is realized by switching
37 between events at a user specified time interval.
39 If unsure, say N.
41 config HAVE_OPROFILE
42 bool
44 config OPROFILE_NMI_TIMER
45 def_bool y
46 depends on PERF_EVENTS && HAVE_PERF_EVENTS_NMI && !PPC64
48 config KPROBES
49 bool "Kprobes"
50 depends on MODULES
51 depends on HAVE_KPROBES
52 select KALLSYMS
53 help
54 Kprobes allows you to trap at almost any kernel address and
55 execute a callback function. register_kprobe() establishes
56 a probepoint and specifies the callback. Kprobes is useful
57 for kernel debugging, non-intrusive instrumentation and testing.
58 If in doubt, say "N".
60 config JUMP_LABEL
61 bool "Optimize very unlikely/likely branches"
62 depends on HAVE_ARCH_JUMP_LABEL
63 help
64 This option enables a transparent branch optimization that
65 makes certain almost-always-true or almost-always-false branch
66 conditions even cheaper to execute within the kernel.
68 Certain performance-sensitive kernel code, such as trace points,
69 scheduler functionality, networking code and KVM have such
70 branches and include support for this optimization technique.
72 If it is detected that the compiler has support for "asm goto",
73 the kernel will compile such branches with just a nop
74 instruction. When the condition flag is toggled to true, the
75 nop will be converted to a jump instruction to execute the
76 conditional block of instructions.
78 This technique lowers overhead and stress on the branch prediction
79 of the processor and generally makes the kernel faster. The update
80 of the condition is slower, but those are always very rare.
82 ( On 32-bit x86, the necessary options added to the compiler
83 flags may increase the size of the kernel slightly. )
85 config STATIC_KEYS_SELFTEST
86 bool "Static key selftest"
87 depends on JUMP_LABEL
88 help
89 Boot time self-test of the branch patching code.
91 config OPTPROBES
92 def_bool y
93 depends on KPROBES && HAVE_OPTPROBES
94 select TASKS_RCU if PREEMPT
96 config KPROBES_ON_FTRACE
97 def_bool y
98 depends on KPROBES && HAVE_KPROBES_ON_FTRACE
99 depends on DYNAMIC_FTRACE_WITH_REGS
100 help
101 If function tracer is enabled and the arch supports full
102 passing of pt_regs to function tracing, then kprobes can
103 optimize on top of function tracing.
105 config UPROBES
106 def_bool n
107 depends on ARCH_SUPPORTS_UPROBES
108 help
109 Uprobes is the user-space counterpart to kprobes: they
110 enable instrumentation applications (such as 'perf probe')
111 to establish unintrusive probes in user-space binaries and
112 libraries, by executing handler functions when the probes
113 are hit by user-space applications.
115 ( These probes come in the form of single-byte breakpoints,
116 managed by the kernel and kept transparent to the probed
117 application. )
119 config HAVE_64BIT_ALIGNED_ACCESS
120 def_bool 64BIT && !HAVE_EFFICIENT_UNALIGNED_ACCESS
121 help
122 Some architectures require 64 bit accesses to be 64 bit
123 aligned, which also requires structs containing 64 bit values
124 to be 64 bit aligned too. This includes some 32 bit
125 architectures which can do 64 bit accesses, as well as 64 bit
126 architectures without unaligned access.
128 This symbol should be selected by an architecture if 64 bit
129 accesses are required to be 64 bit aligned in this way even
130 though it is not a 64 bit architecture.
132 See Documentation/unaligned-memory-access.txt for more
133 information on the topic of unaligned memory accesses.
135 config HAVE_EFFICIENT_UNALIGNED_ACCESS
136 bool
137 help
138 Some architectures are unable to perform unaligned accesses
139 without the use of get_unaligned/put_unaligned. Others are
140 unable to perform such accesses efficiently (e.g. trap on
141 unaligned access and require fixing it up in the exception
142 handler.)
144 This symbol should be selected by an architecture if it can
145 perform unaligned accesses efficiently to allow different
146 code paths to be selected for these cases. Some network
147 drivers, for example, could opt to not fix up alignment
148 problems with received packets if doing so would not help
149 much.
151 See Documentation/unaligned-memory-access.txt for more
152 information on the topic of unaligned memory accesses.
154 config ARCH_USE_BUILTIN_BSWAP
155 bool
156 help
157 Modern versions of GCC (since 4.4) have builtin functions
158 for handling byte-swapping. Using these, instead of the old
159 inline assembler that the architecture code provides in the
160 __arch_bswapXX() macros, allows the compiler to see what's
161 happening and offers more opportunity for optimisation. In
162 particular, the compiler will be able to combine the byteswap
163 with a nearby load or store and use load-and-swap or
164 store-and-swap instructions if the architecture has them. It
165 should almost *never* result in code which is worse than the
166 hand-coded assembler in <asm/swab.h>. But just in case it
167 does, the use of the builtins is optional.
169 Any architecture with load-and-swap or store-and-swap
170 instructions should set this. And it shouldn't hurt to set it
171 on architectures that don't have such instructions.
173 config KRETPROBES
174 def_bool y
175 depends on KPROBES && HAVE_KRETPROBES
177 config USER_RETURN_NOTIFIER
178 bool
179 depends on HAVE_USER_RETURN_NOTIFIER
180 help
181 Provide a kernel-internal notification when a cpu is about to
182 switch to user mode.
184 config HAVE_IOREMAP_PROT
185 bool
187 config HAVE_KPROBES
188 bool
190 config HAVE_KRETPROBES
191 bool
193 config HAVE_OPTPROBES
194 bool
196 config HAVE_KPROBES_ON_FTRACE
197 bool
199 config HAVE_NMI
200 bool
202 #
203 # An arch should select this if it provides all these things:
204 #
205 # task_pt_regs() in asm/processor.h or asm/ptrace.h
206 # arch_has_single_step() if there is hardware single-step support
207 # arch_has_block_step() if there is hardware block-step support
208 # asm/syscall.h supplying asm-generic/syscall.h interface
209 # linux/regset.h user_regset interfaces
210 # CORE_DUMP_USE_REGSET #define'd in linux/elf.h
211 # TIF_SYSCALL_TRACE calls tracehook_report_syscall_{entry,exit}
212 # TIF_NOTIFY_RESUME calls tracehook_notify_resume()
213 # signal delivery calls tracehook_signal_handler()
214 #
215 config HAVE_ARCH_TRACEHOOK
216 bool
218 config HAVE_DMA_CONTIGUOUS
219 bool
221 config GENERIC_SMP_IDLE_THREAD
222 bool
224 config GENERIC_IDLE_POLL_SETUP
225 bool
227 config ARCH_HAS_FORTIFY_SOURCE
228 bool
229 help
230 An architecture should select this when it can successfully
231 build and run with CONFIG_FORTIFY_SOURCE.
233 # Select if arch has all set_memory_ro/rw/x/nx() functions in asm/cacheflush.h
234 config ARCH_HAS_SET_MEMORY
235 bool
237 # Select if arch init_task initializer is different to init/init_task.c
238 config ARCH_INIT_TASK
239 bool
241 # Select if arch has its private alloc_task_struct() function
242 config ARCH_TASK_STRUCT_ALLOCATOR
243 bool
245 # Select if arch has its private alloc_thread_stack() function
246 config ARCH_THREAD_STACK_ALLOCATOR
247 bool
249 # Select if arch wants to size task_struct dynamically via arch_task_struct_size:
250 config ARCH_WANTS_DYNAMIC_TASK_STRUCT
251 bool
253 config HAVE_REGS_AND_STACK_ACCESS_API
254 bool
255 help
256 This symbol should be selected by an architecure if it supports
257 the API needed to access registers and stack entries from pt_regs,
258 declared in asm/ptrace.h
259 For example the kprobes-based event tracer needs this API.
261 config HAVE_CLK
262 bool
263 help
264 The <linux/clk.h> calls support software clock gating and
265 thus are a key power management tool on many systems.
267 config HAVE_DMA_API_DEBUG
268 bool
270 config HAVE_HW_BREAKPOINT
271 bool
272 depends on PERF_EVENTS
274 config HAVE_MIXED_BREAKPOINTS_REGS
275 bool
276 depends on HAVE_HW_BREAKPOINT
277 help
278 Depending on the arch implementation of hardware breakpoints,
279 some of them have separate registers for data and instruction
280 breakpoints addresses, others have mixed registers to store
281 them but define the access type in a control register.
282 Select this option if your arch implements breakpoints under the
283 latter fashion.
285 config HAVE_USER_RETURN_NOTIFIER
286 bool
288 config HAVE_PERF_EVENTS_NMI
289 bool
290 help
291 System hardware can generate an NMI using the perf event
292 subsystem. Also has support for calculating CPU cycle events
293 to determine how many clock cycles in a given period.
295 config HAVE_HARDLOCKUP_DETECTOR_PERF
296 bool
297 depends on HAVE_PERF_EVENTS_NMI
298 help
299 The arch chooses to use the generic perf-NMI-based hardlockup
300 detector. Must define HAVE_PERF_EVENTS_NMI.
302 config HAVE_NMI_WATCHDOG
303 depends on HAVE_NMI
304 bool
305 help
306 The arch provides a low level NMI watchdog. It provides
307 asm/nmi.h, and defines its own arch_touch_nmi_watchdog().
309 config HAVE_HARDLOCKUP_DETECTOR_ARCH
310 bool
311 select HAVE_NMI_WATCHDOG
312 help
313 The arch chooses to provide its own hardlockup detector, which is
314 a superset of the HAVE_NMI_WATCHDOG. It also conforms to config
315 interfaces and parameters provided by hardlockup detector subsystem.
317 config HAVE_PERF_REGS
318 bool
319 help
320 Support selective register dumps for perf events. This includes
321 bit-mapping of each registers and a unique architecture id.
323 config HAVE_PERF_USER_STACK_DUMP
324 bool
325 help
326 Support user stack dumps for perf event samples. This needs
327 access to the user stack pointer which is not unified across
328 architectures.
330 config HAVE_ARCH_JUMP_LABEL
331 bool
333 config HAVE_RCU_TABLE_FREE
334 bool
336 config ARCH_HAVE_NMI_SAFE_CMPXCHG
337 bool
339 config HAVE_ALIGNED_STRUCT_PAGE
340 bool
341 help
342 This makes sure that struct pages are double word aligned and that
343 e.g. the SLUB allocator can perform double word atomic operations
344 on a struct page for better performance. However selecting this
345 might increase the size of a struct page by a word.
347 config HAVE_CMPXCHG_LOCAL
348 bool
350 config HAVE_CMPXCHG_DOUBLE
351 bool
353 config ARCH_WEAK_RELEASE_ACQUIRE
354 bool
356 config ARCH_WANT_IPC_PARSE_VERSION
357 bool
359 config ARCH_WANT_COMPAT_IPC_PARSE_VERSION
360 bool
362 config ARCH_WANT_OLD_COMPAT_IPC
363 select ARCH_WANT_COMPAT_IPC_PARSE_VERSION
364 bool
366 config HAVE_ARCH_SECCOMP_FILTER
367 bool
368 help
369 An arch should select this symbol if it provides all of these things:
370 - syscall_get_arch()
371 - syscall_get_arguments()
372 - syscall_rollback()
373 - syscall_set_return_value()
374 - SIGSYS siginfo_t support
375 - secure_computing is called from a ptrace_event()-safe context
376 - secure_computing return value is checked and a return value of -1
377 results in the system call being skipped immediately.
378 - seccomp syscall wired up
380 config SECCOMP_FILTER
381 def_bool y
382 depends on HAVE_ARCH_SECCOMP_FILTER && SECCOMP && NET
383 help
384 Enable tasks to build secure computing environments defined
385 in terms of Berkeley Packet Filter programs which implement
386 task-defined system call filtering polices.
388 See Documentation/prctl/seccomp_filter.txt for details.
390 config HAVE_GCC_PLUGINS
391 bool
392 help
393 An arch should select this symbol if it supports building with
394 GCC plugins.
396 menuconfig GCC_PLUGINS
397 bool "GCC plugins"
398 depends on HAVE_GCC_PLUGINS
399 depends on !COMPILE_TEST
400 help
401 GCC plugins are loadable modules that provide extra features to the
402 compiler. They are useful for runtime instrumentation and static analysis.
404 See Documentation/gcc-plugins.txt for details.
406 config GCC_PLUGIN_CYC_COMPLEXITY
407 bool "Compute the cyclomatic complexity of a function" if EXPERT
408 depends on GCC_PLUGINS
409 depends on !COMPILE_TEST
410 help
411 The complexity M of a function's control flow graph is defined as:
412 M = E - N + 2P
413 where
415 E = the number of edges
416 N = the number of nodes
417 P = the number of connected components (exit nodes).
419 Enabling this plugin reports the complexity to stderr during the
420 build. It mainly serves as a simple example of how to create a
421 gcc plugin for the kernel.
423 config GCC_PLUGIN_SANCOV
424 bool
425 depends on GCC_PLUGINS
426 help
427 This plugin inserts a __sanitizer_cov_trace_pc() call at the start of
428 basic blocks. It supports all gcc versions with plugin support (from
429 gcc-4.5 on). It is based on the commit "Add fuzzing coverage support"
430 by Dmitry Vyukov <dvyukov@google.com>.
432 config GCC_PLUGIN_LATENT_ENTROPY
433 bool "Generate some entropy during boot and runtime"
434 depends on GCC_PLUGINS
435 help
436 By saying Y here the kernel will instrument some kernel code to
437 extract some entropy from both original and artificially created
438 program state. This will help especially embedded systems where
439 there is little 'natural' source of entropy normally. The cost
440 is some slowdown of the boot process (about 0.5%) and fork and
441 irq processing.
443 Note that entropy extracted this way is not cryptographically
444 secure!
446 This plugin was ported from grsecurity/PaX. More information at:
447 * https://grsecurity.net/
448 * https://pax.grsecurity.net/
450 config GCC_PLUGIN_STRUCTLEAK
451 bool "Force initialization of variables containing userspace addresses"
452 depends on GCC_PLUGINS
453 help
454 This plugin zero-initializes any structures containing a
455 __user attribute. This can prevent some classes of information
456 exposures.
458 This plugin was ported from grsecurity/PaX. More information at:
459 * https://grsecurity.net/
460 * https://pax.grsecurity.net/
462 config GCC_PLUGIN_STRUCTLEAK_BYREF_ALL
463 bool "Force initialize all struct type variables passed by reference"
464 depends on GCC_PLUGIN_STRUCTLEAK
465 help
466 Zero initialize any struct type local variable that may be passed by
467 reference without having been initialized.
469 config GCC_PLUGIN_STRUCTLEAK_VERBOSE
470 bool "Report forcefully initialized variables"
471 depends on GCC_PLUGIN_STRUCTLEAK
472 depends on !COMPILE_TEST
473 help
474 This option will cause a warning to be printed each time the
475 structleak plugin finds a variable it thinks needs to be
476 initialized. Since not all existing initializers are detected
477 by the plugin, this can produce false positive warnings.
479 config GCC_PLUGIN_RANDSTRUCT
480 bool "Randomize layout of sensitive kernel structures"
481 depends on GCC_PLUGINS
482 select MODVERSIONS if MODULES
483 help
484 If you say Y here, the layouts of structures that are entirely
485 function pointers (and have not been manually annotated with
486 __no_randomize_layout), or structures that have been explicitly
487 marked with __randomize_layout, will be randomized at compile-time.
488 This can introduce the requirement of an additional information
489 exposure vulnerability for exploits targeting these structure
490 types.
492 Enabling this feature will introduce some performance impact,
493 slightly increase memory usage, and prevent the use of forensic
494 tools like Volatility against the system (unless the kernel
495 source tree isn't cleaned after kernel installation).
497 The seed used for compilation is located at
498 scripts/gcc-plgins/randomize_layout_seed.h. It remains after
499 a make clean to allow for external modules to be compiled with
500 the existing seed and will be removed by a make mrproper or
501 make distclean.
503 Note that the implementation requires gcc 4.7 or newer.
505 This plugin was ported from grsecurity/PaX. More information at:
506 * https://grsecurity.net/
507 * https://pax.grsecurity.net/
509 config GCC_PLUGIN_RANDSTRUCT_PERFORMANCE
510 bool "Use cacheline-aware structure randomization"
511 depends on GCC_PLUGIN_RANDSTRUCT
512 depends on !COMPILE_TEST
513 help
514 If you say Y here, the RANDSTRUCT randomization will make a
515 best effort at restricting randomization to cacheline-sized
516 groups of elements. It will further not randomize bitfields
517 in structures. This reduces the performance hit of RANDSTRUCT
518 at the cost of weakened randomization.
520 config HAVE_CC_STACKPROTECTOR
521 bool
522 help
523 An arch should select this symbol if:
524 - its compiler supports the -fstack-protector option
525 - it has implemented a stack canary (e.g. __stack_chk_guard)
527 config CC_STACKPROTECTOR
528 def_bool n
529 help
530 Set when a stack-protector mode is enabled, so that the build
531 can enable kernel-side support for the GCC feature.
533 choice
534 prompt "Stack Protector buffer overflow detection"
535 depends on HAVE_CC_STACKPROTECTOR
536 default CC_STACKPROTECTOR_NONE
537 help
538 This option turns on the "stack-protector" GCC feature. This
539 feature puts, at the beginning of functions, a canary value on
540 the stack just before the return address, and validates
541 the value just before actually returning. Stack based buffer
542 overflows (that need to overwrite this return address) now also
543 overwrite the canary, which gets detected and the attack is then
544 neutralized via a kernel panic.
546 config CC_STACKPROTECTOR_NONE
547 bool "None"
548 help
549 Disable "stack-protector" GCC feature.
551 config CC_STACKPROTECTOR_REGULAR
552 bool "Regular"
553 select CC_STACKPROTECTOR
554 help
555 Functions will have the stack-protector canary logic added if they
556 have an 8-byte or larger character array on the stack.
558 This feature requires gcc version 4.2 or above, or a distribution
559 gcc with the feature backported ("-fstack-protector").
561 On an x86 "defconfig" build, this feature adds canary checks to
562 about 3% of all kernel functions, which increases kernel code size
563 by about 0.3%.
565 config CC_STACKPROTECTOR_STRONG
566 bool "Strong"
567 select CC_STACKPROTECTOR
568 help
569 Functions will have the stack-protector canary logic added in any
570 of the following conditions:
572 - local variable's address used as part of the right hand side of an
573 assignment or function argument
574 - local variable is an array (or union containing an array),
575 regardless of array type or length
576 - uses register local variables
578 This feature requires gcc version 4.9 or above, or a distribution
579 gcc with the feature backported ("-fstack-protector-strong").
581 On an x86 "defconfig" build, this feature adds canary checks to
582 about 20% of all kernel functions, which increases the kernel code
583 size by about 2%.
585 endchoice
587 config THIN_ARCHIVES
588 def_bool y
589 help
590 Select this if the architecture wants to use thin archives
591 instead of ld -r to create the built-in.o files.
593 config LD_DEAD_CODE_DATA_ELIMINATION
594 bool
595 help
596 Select this if the architecture wants to do dead code and
597 data elimination with the linker by compiling with
598 -ffunction-sections -fdata-sections and linking with
599 --gc-sections.
601 This requires that the arch annotates or otherwise protects
602 its external entry points from being discarded. Linker scripts
603 must also merge .text.*, .data.*, and .bss.* correctly into
604 output sections. Care must be taken not to pull in unrelated
605 sections (e.g., '.text.init'). Typically '.' in section names
606 is used to distinguish them from label names / C identifiers.
608 config HAVE_ARCH_WITHIN_STACK_FRAMES
609 bool
610 help
611 An architecture should select this if it can walk the kernel stack
612 frames to determine if an object is part of either the arguments
613 or local variables (i.e. that it excludes saved return addresses,
614 and similar) by implementing an inline arch_within_stack_frames(),
615 which is used by CONFIG_HARDENED_USERCOPY.
617 config HAVE_CONTEXT_TRACKING
618 bool
619 help
620 Provide kernel/user boundaries probes necessary for subsystems
621 that need it, such as userspace RCU extended quiescent state.
622 Syscalls need to be wrapped inside user_exit()-user_enter() through
623 the slow path using TIF_NOHZ flag. Exceptions handlers must be
624 wrapped as well. Irqs are already protected inside
625 rcu_irq_enter/rcu_irq_exit() but preemption or signal handling on
626 irq exit still need to be protected.
628 config HAVE_VIRT_CPU_ACCOUNTING
629 bool
631 config ARCH_HAS_SCALED_CPUTIME
632 bool
634 config HAVE_VIRT_CPU_ACCOUNTING_GEN
635 bool
636 default y if 64BIT
637 help
638 With VIRT_CPU_ACCOUNTING_GEN, cputime_t becomes 64-bit.
639 Before enabling this option, arch code must be audited
640 to ensure there are no races in concurrent read/write of
641 cputime_t. For example, reading/writing 64-bit cputime_t on
642 some 32-bit arches may require multiple accesses, so proper
643 locking is needed to protect against concurrent accesses.
646 config HAVE_IRQ_TIME_ACCOUNTING
647 bool
648 help
649 Archs need to ensure they use a high enough resolution clock to
650 support irq time accounting and then call enable_sched_clock_irqtime().
652 config HAVE_ARCH_TRANSPARENT_HUGEPAGE
653 bool
655 config HAVE_ARCH_TRANSPARENT_HUGEPAGE_PUD
656 bool
658 config HAVE_ARCH_HUGE_VMAP
659 bool
661 config HAVE_ARCH_SOFT_DIRTY
662 bool
664 config HAVE_MOD_ARCH_SPECIFIC
665 bool
666 help
667 The arch uses struct mod_arch_specific to store data. Many arches
668 just need a simple module loader without arch specific data - those
669 should not enable this.
671 config MODULES_USE_ELF_RELA
672 bool
673 help
674 Modules only use ELF RELA relocations. Modules with ELF REL
675 relocations will give an error.
677 config MODULES_USE_ELF_REL
678 bool
679 help
680 Modules only use ELF REL relocations. Modules with ELF RELA
681 relocations will give an error.
683 config HAVE_UNDERSCORE_SYMBOL_PREFIX
684 bool
685 help
686 Some architectures generate an _ in front of C symbols; things like
687 module loading and assembly files need to know about this.
689 config HAVE_IRQ_EXIT_ON_IRQ_STACK
690 bool
691 help
692 Architecture doesn't only execute the irq handler on the irq stack
693 but also irq_exit(). This way we can process softirqs on this irq
694 stack instead of switching to a new one when we call __do_softirq()
695 in the end of an hardirq.
696 This spares a stack switch and improves cache usage on softirq
697 processing.
699 config PGTABLE_LEVELS
700 int
701 default 2
703 config ARCH_HAS_ELF_RANDOMIZE
704 bool
705 help
706 An architecture supports choosing randomized locations for
707 stack, mmap, brk, and ET_DYN. Defined functions:
708 - arch_mmap_rnd()
709 - arch_randomize_brk()
711 config HAVE_ARCH_MMAP_RND_BITS
712 bool
713 help
714 An arch should select this symbol if it supports setting a variable
715 number of bits for use in establishing the base address for mmap
716 allocations, has MMU enabled and provides values for both:
717 - ARCH_MMAP_RND_BITS_MIN
718 - ARCH_MMAP_RND_BITS_MAX
720 config HAVE_EXIT_THREAD
721 bool
722 help
723 An architecture implements exit_thread.
725 config ARCH_MMAP_RND_BITS_MIN
726 int
728 config ARCH_MMAP_RND_BITS_MAX
729 int
731 config ARCH_MMAP_RND_BITS_DEFAULT
732 int
734 config ARCH_MMAP_RND_BITS
735 int "Number of bits to use for ASLR of mmap base address" if EXPERT
736 range ARCH_MMAP_RND_BITS_MIN ARCH_MMAP_RND_BITS_MAX
737 default ARCH_MMAP_RND_BITS_DEFAULT if ARCH_MMAP_RND_BITS_DEFAULT
738 default ARCH_MMAP_RND_BITS_MIN
739 depends on HAVE_ARCH_MMAP_RND_BITS
740 help
741 This value can be used to select the number of bits to use to
742 determine the random offset to the base address of vma regions
743 resulting from mmap allocations. This value will be bounded
744 by the architecture's minimum and maximum supported values.
746 This value can be changed after boot using the
747 /proc/sys/vm/mmap_rnd_bits tunable
749 config HAVE_ARCH_MMAP_RND_COMPAT_BITS
750 bool
751 help
752 An arch should select this symbol if it supports running applications
753 in compatibility mode, supports setting a variable number of bits for
754 use in establishing the base address for mmap allocations, has MMU
755 enabled and provides values for both:
756 - ARCH_MMAP_RND_COMPAT_BITS_MIN
757 - ARCH_MMAP_RND_COMPAT_BITS_MAX
759 config ARCH_MMAP_RND_COMPAT_BITS_MIN
760 int
762 config ARCH_MMAP_RND_COMPAT_BITS_MAX
763 int
765 config ARCH_MMAP_RND_COMPAT_BITS_DEFAULT
766 int
768 config ARCH_MMAP_RND_COMPAT_BITS
769 int "Number of bits to use for ASLR of mmap base address for compatible applications" if EXPERT
770 range ARCH_MMAP_RND_COMPAT_BITS_MIN ARCH_MMAP_RND_COMPAT_BITS_MAX
771 default ARCH_MMAP_RND_COMPAT_BITS_DEFAULT if ARCH_MMAP_RND_COMPAT_BITS_DEFAULT
772 default ARCH_MMAP_RND_COMPAT_BITS_MIN
773 depends on HAVE_ARCH_MMAP_RND_COMPAT_BITS
774 help
775 This value can be used to select the number of bits to use to
776 determine the random offset to the base address of vma regions
777 resulting from mmap allocations for compatible applications This
778 value will be bounded by the architecture's minimum and maximum
779 supported values.
781 This value can be changed after boot using the
782 /proc/sys/vm/mmap_rnd_compat_bits tunable
784 config HAVE_ARCH_COMPAT_MMAP_BASES
785 bool
786 help
787 This allows 64bit applications to invoke 32-bit mmap() syscall
788 and vice-versa 32-bit applications to call 64-bit mmap().
789 Required for applications doing different bitness syscalls.
791 config HAVE_COPY_THREAD_TLS
792 bool
793 help
794 Architecture provides copy_thread_tls to accept tls argument via
795 normal C parameter passing, rather than extracting the syscall
796 argument from pt_regs.
798 config HAVE_STACK_VALIDATION
799 bool
800 help
801 Architecture supports the 'objtool check' host tool command, which
802 performs compile-time stack metadata validation.
804 config HAVE_RELIABLE_STACKTRACE
805 bool
806 help
807 Architecture has a save_stack_trace_tsk_reliable() function which
808 only returns a stack trace if it can guarantee the trace is reliable.
810 config HAVE_ARCH_HASH
811 bool
812 default n
813 help
814 If this is set, the architecture provides an <asm/hash.h>
815 file which provides platform-specific implementations of some
816 functions in <linux/hash.h> or fs/namei.c.
818 config ISA_BUS_API
819 def_bool ISA
821 #
822 # ABI hall of shame
823 #
824 config CLONE_BACKWARDS
825 bool
826 help
827 Architecture has tls passed as the 4th argument of clone(2),
828 not the 5th one.
830 config CLONE_BACKWARDS2
831 bool
832 help
833 Architecture has the first two arguments of clone(2) swapped.
835 config CLONE_BACKWARDS3
836 bool
837 help
838 Architecture has tls passed as the 3rd argument of clone(2),
839 not the 5th one.
841 config ODD_RT_SIGACTION
842 bool
843 help
844 Architecture has unusual rt_sigaction(2) arguments
846 config OLD_SIGSUSPEND
847 bool
848 help
849 Architecture has old sigsuspend(2) syscall, of one-argument variety
851 config OLD_SIGSUSPEND3
852 bool
853 help
854 Even weirder antique ABI - three-argument sigsuspend(2)
856 config OLD_SIGACTION
857 bool
858 help
859 Architecture has old sigaction(2) syscall. Nope, not the same
860 as OLD_SIGSUSPEND | OLD_SIGSUSPEND3 - alpha has sigsuspend(2),
861 but fairly different variant of sigaction(2), thanks to OSF/1
862 compatibility...
864 config COMPAT_OLD_SIGACTION
865 bool
867 config ARCH_NO_COHERENT_DMA_MMAP
868 bool
870 config CPU_NO_EFFICIENT_FFS
871 def_bool n
873 config HAVE_ARCH_VMAP_STACK
874 def_bool n
875 help
876 An arch should select this symbol if it can support kernel stacks
877 in vmalloc space. This means:
879 - vmalloc space must be large enough to hold many kernel stacks.
880 This may rule out many 32-bit architectures.
882 - Stacks in vmalloc space need to work reliably. For example, if
883 vmap page tables are created on demand, either this mechanism
884 needs to work while the stack points to a virtual address with
885 unpopulated page tables or arch code (switch_to() and switch_mm(),
886 most likely) needs to ensure that the stack's page table entries
887 are populated before running on a possibly unpopulated stack.
889 - If the stack overflows into a guard page, something reasonable
890 should happen. The definition of "reasonable" is flexible, but
891 instantly rebooting without logging anything would be unfriendly.
893 config VMAP_STACK
894 default y
895 bool "Use a virtually-mapped stack"
896 depends on HAVE_ARCH_VMAP_STACK && !KASAN
897 ---help---
898 Enable this if you want the use virtually-mapped kernel stacks
899 with guard pages. This causes kernel stack overflows to be
900 caught immediately rather than causing difficult-to-diagnose
901 corruption.
903 This is presently incompatible with KASAN because KASAN expects
904 the stack to map directly to the KASAN shadow map using a formula
905 that is incorrect if the stack is in vmalloc space.
907 config ARCH_OPTIONAL_KERNEL_RWX
908 def_bool n
910 config ARCH_OPTIONAL_KERNEL_RWX_DEFAULT
911 def_bool n
913 config ARCH_HAS_STRICT_KERNEL_RWX
914 def_bool n
916 config STRICT_KERNEL_RWX
917 bool "Make kernel text and rodata read-only" if ARCH_OPTIONAL_KERNEL_RWX
918 depends on ARCH_HAS_STRICT_KERNEL_RWX
919 default !ARCH_OPTIONAL_KERNEL_RWX || ARCH_OPTIONAL_KERNEL_RWX_DEFAULT
920 help
921 If this is set, kernel 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. executing the heap
924 or modifying text)
926 These features are considered standard security practice these days.
927 You should say Y here in almost all cases.
929 config ARCH_HAS_STRICT_MODULE_RWX
930 def_bool n
932 config STRICT_MODULE_RWX
933 bool "Set loadable kernel module data as NX and text as RO" if ARCH_OPTIONAL_KERNEL_RWX
934 depends on ARCH_HAS_STRICT_MODULE_RWX && MODULES
935 default !ARCH_OPTIONAL_KERNEL_RWX || ARCH_OPTIONAL_KERNEL_RWX_DEFAULT
936 help
937 If this is set, module 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. writing to text)
941 config ARCH_HAS_REFCOUNT
942 bool
943 help
944 An architecture selects this when it has implemented refcount_t
945 using open coded assembly primitives that provide an optimized
946 refcount_t implementation, possibly at the expense of some full
947 refcount state checks of CONFIG_REFCOUNT_FULL=y.
949 The refcount overflow check behavior, however, must be retained.
950 Catching overflows is the primary security concern for protecting
951 against bugs in reference counts.
953 config REFCOUNT_FULL
954 bool "Perform full reference count validation at the expense of speed"
955 help
956 Enabling this switches the refcounting infrastructure from a fast
957 unchecked atomic_t implementation to a fully state checked
958 implementation, which can be (slightly) slower but provides protections
959 against various use-after-free conditions that can be used in
960 security flaw exploits.
962 source "kernel/gcov/Kconfig"