1# SPDX-License-Identifier: GPL-2.0 2# 3# General architecture dependent options 4# 5 6# 7# Note: arch/$(SRCARCH)/Kconfig needs to be included first so that it can 8# override the default values in this file. 9# 10source "arch/$(SRCARCH)/Kconfig" 11 12menu "General architecture-dependent options" 13 14config CRASH_CORE 15 bool 16 17config KEXEC_CORE 18 select CRASH_CORE 19 bool 20 21config HAVE_IMA_KEXEC 22 bool 23 24config HOTPLUG_SMT 25 bool 26 27config OPROFILE 28 tristate "OProfile system profiling" 29 depends on PROFILING 30 depends on HAVE_OPROFILE 31 select RING_BUFFER 32 select RING_BUFFER_ALLOW_SWAP 33 help 34 OProfile is a profiling system capable of profiling the 35 whole system, include the kernel, kernel modules, libraries, 36 and applications. 37 38 If unsure, say N. 39 40config OPROFILE_EVENT_MULTIPLEX 41 bool "OProfile multiplexing support (EXPERIMENTAL)" 42 default n 43 depends on OPROFILE && X86 44 help 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. 49 50 If unsure, say N. 51 52config HAVE_OPROFILE 53 bool 54 55config OPROFILE_NMI_TIMER 56 def_bool y 57 depends on PERF_EVENTS && HAVE_PERF_EVENTS_NMI && !PPC64 58 59config KPROBES 60 bool "Kprobes" 61 depends on MODULES 62 depends on HAVE_KPROBES 63 select KALLSYMS 64 help 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. 69 If in doubt, say "N". 70 71config JUMP_LABEL 72 bool "Optimize very unlikely/likely branches" 73 depends on HAVE_ARCH_JUMP_LABEL 74 depends on CC_HAS_ASM_GOTO 75 help 76 This option enables a transparent branch optimization that 77 makes certain almost-always-true or almost-always-false branch 78 conditions even cheaper to execute within the kernel. 79 80 Certain performance-sensitive kernel code, such as trace points, 81 scheduler functionality, networking code and KVM have such 82 branches and include support for this optimization technique. 83 84 If it is detected that the compiler has support for "asm goto", 85 the kernel will compile such branches with just a nop 86 instruction. When the condition flag is toggled to true, the 87 nop will be converted to a jump instruction to execute the 88 conditional block of instructions. 89 90 This technique lowers overhead and stress on the branch prediction 91 of the processor and generally makes the kernel faster. The update 92 of the condition is slower, but those are always very rare. 93 94 ( On 32-bit x86, the necessary options added to the compiler 95 flags may increase the size of the kernel slightly. ) 96 97config STATIC_KEYS_SELFTEST 98 bool "Static key selftest" 99 depends on JUMP_LABEL 100 help 101 Boot time self-test of the branch patching code. 102 103config OPTPROBES 104 def_bool y 105 depends on KPROBES && HAVE_OPTPROBES 106 select TASKS_RCU if PREEMPT 107 108config KPROBES_ON_FTRACE 109 def_bool y 110 depends on KPROBES && HAVE_KPROBES_ON_FTRACE 111 depends on DYNAMIC_FTRACE_WITH_REGS 112 help 113 If function tracer is enabled and the arch supports full 114 passing of pt_regs to function tracing, then kprobes can 115 optimize on top of function tracing. 116 117config UPROBES 118 def_bool n 119 depends on ARCH_SUPPORTS_UPROBES 120 help 121 Uprobes is the user-space counterpart to kprobes: they 122 enable instrumentation applications (such as 'perf probe') 123 to establish unintrusive probes in user-space binaries and 124 libraries, by executing handler functions when the probes 125 are hit by user-space applications. 126 127 ( These probes come in the form of single-byte breakpoints, 128 managed by the kernel and kept transparent to the probed 129 application. ) 130 131config HAVE_EFFICIENT_UNALIGNED_ACCESS 132 bool 133 help 134 Some architectures are unable to perform unaligned accesses 135 without the use of get_unaligned/put_unaligned. Others are 136 unable to perform such accesses efficiently (e.g. trap on 137 unaligned access and require fixing it up in the exception 138 handler.) 139 140 This symbol should be selected by an architecture if it can 141 perform unaligned accesses efficiently to allow different 142 code paths to be selected for these cases. Some network 143 drivers, for example, could opt to not fix up alignment 144 problems with received packets if doing so would not help 145 much. 146 147 See Documentation/unaligned-memory-access.txt for more 148 information on the topic of unaligned memory accesses. 149 150config ARCH_USE_BUILTIN_BSWAP 151 bool 152 help 153 Modern versions of GCC (since 4.4) have builtin functions 154 for handling byte-swapping. Using these, instead of the old 155 inline assembler that the architecture code provides in the 156 __arch_bswapXX() macros, allows the compiler to see what's 157 happening and offers more opportunity for optimisation. In 158 particular, the compiler will be able to combine the byteswap 159 with a nearby load or store and use load-and-swap or 160 store-and-swap instructions if the architecture has them. It 161 should almost *never* result in code which is worse than the 162 hand-coded assembler in <asm/swab.h>. But just in case it 163 does, the use of the builtins is optional. 164 165 Any architecture with load-and-swap or store-and-swap 166 instructions should set this. And it shouldn't hurt to set it 167 on architectures that don't have such instructions. 168 169config KRETPROBES 170 def_bool y 171 depends on KPROBES && HAVE_KRETPROBES 172 173config USER_RETURN_NOTIFIER 174 bool 175 depends on HAVE_USER_RETURN_NOTIFIER 176 help 177 Provide a kernel-internal notification when a cpu is about to 178 switch to user mode. 179 180config HAVE_IOREMAP_PROT 181 bool 182 183config HAVE_KPROBES 184 bool 185 186config HAVE_KRETPROBES 187 bool 188 189config HAVE_OPTPROBES 190 bool 191 192config HAVE_KPROBES_ON_FTRACE 193 bool 194 195config HAVE_FUNCTION_ERROR_INJECTION 196 bool 197 198config HAVE_NMI 199 bool 200 201# 202# An arch should select this if it provides all these things: 203# 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() 213# 214config HAVE_ARCH_TRACEHOOK 215 bool 216 217config HAVE_DMA_CONTIGUOUS 218 bool 219 220config GENERIC_SMP_IDLE_THREAD 221 bool 222 223config GENERIC_IDLE_POLL_SETUP 224 bool 225 226config ARCH_HAS_FORTIFY_SOURCE 227 bool 228 help 229 An architecture should select this when it can successfully 230 build and run with CONFIG_FORTIFY_SOURCE. 231 232# 233# Select if the arch provides a historic keepinit alias for the retain_initrd 234# command line option 235# 236config ARCH_HAS_KEEPINITRD 237 bool 238 239# Select if arch has all set_memory_ro/rw/x/nx() functions in asm/cacheflush.h 240config ARCH_HAS_SET_MEMORY 241 bool 242 243# Select if arch has all set_direct_map_invalid/default() functions 244config ARCH_HAS_SET_DIRECT_MAP 245 bool 246 247# 248# Select if arch has an uncached kernel segment and provides the 249# uncached_kernel_address / cached_kernel_address symbols to use it 250# 251config ARCH_HAS_UNCACHED_SEGMENT 252 select ARCH_HAS_DMA_PREP_COHERENT 253 bool 254 255# Select if arch init_task must go in the __init_task_data section 256config ARCH_TASK_STRUCT_ON_STACK 257 bool 258 259# Select if arch has its private alloc_task_struct() function 260config ARCH_TASK_STRUCT_ALLOCATOR 261 bool 262 263config HAVE_ARCH_THREAD_STRUCT_WHITELIST 264 bool 265 depends on !ARCH_TASK_STRUCT_ALLOCATOR 266 help 267 An architecture should select this to provide hardened usercopy 268 knowledge about what region of the thread_struct should be 269 whitelisted for copying to userspace. Normally this is only the 270 FPU registers. Specifically, arch_thread_struct_whitelist() 271 should be implemented. Without this, the entire thread_struct 272 field in task_struct will be left whitelisted. 273 274# Select if arch has its private alloc_thread_stack() function 275config ARCH_THREAD_STACK_ALLOCATOR 276 bool 277 278# Select if arch wants to size task_struct dynamically via arch_task_struct_size: 279config ARCH_WANTS_DYNAMIC_TASK_STRUCT 280 bool 281 282config ARCH_32BIT_OFF_T 283 bool 284 depends on !64BIT 285 help 286 All new 32-bit architectures should have 64-bit off_t type on 287 userspace side which corresponds to the loff_t kernel type. This 288 is the requirement for modern ABIs. Some existing architectures 289 still support 32-bit off_t. This option is enabled for all such 290 architectures explicitly. 291 292config HAVE_REGS_AND_STACK_ACCESS_API 293 bool 294 help 295 This symbol should be selected by an architecure if it supports 296 the API needed to access registers and stack entries from pt_regs, 297 declared in asm/ptrace.h 298 For example the kprobes-based event tracer needs this API. 299 300config HAVE_RSEQ 301 bool 302 depends on HAVE_REGS_AND_STACK_ACCESS_API 303 help 304 This symbol should be selected by an architecture if it 305 supports an implementation of restartable sequences. 306 307config HAVE_FUNCTION_ARG_ACCESS_API 308 bool 309 help 310 This symbol should be selected by an architecure if it supports 311 the API needed to access function arguments from pt_regs, 312 declared in asm/ptrace.h 313 314config HAVE_CLK 315 bool 316 help 317 The <linux/clk.h> calls support software clock gating and 318 thus are a key power management tool on many systems. 319 320config HAVE_HW_BREAKPOINT 321 bool 322 depends on PERF_EVENTS 323 324config HAVE_MIXED_BREAKPOINTS_REGS 325 bool 326 depends on HAVE_HW_BREAKPOINT 327 help 328 Depending on the arch implementation of hardware breakpoints, 329 some of them have separate registers for data and instruction 330 breakpoints addresses, others have mixed registers to store 331 them but define the access type in a control register. 332 Select this option if your arch implements breakpoints under the 333 latter fashion. 334 335config HAVE_USER_RETURN_NOTIFIER 336 bool 337 338config HAVE_PERF_EVENTS_NMI 339 bool 340 help 341 System hardware can generate an NMI using the perf event 342 subsystem. Also has support for calculating CPU cycle events 343 to determine how many clock cycles in a given period. 344 345config HAVE_HARDLOCKUP_DETECTOR_PERF 346 bool 347 depends on HAVE_PERF_EVENTS_NMI 348 help 349 The arch chooses to use the generic perf-NMI-based hardlockup 350 detector. Must define HAVE_PERF_EVENTS_NMI. 351 352config HAVE_NMI_WATCHDOG 353 depends on HAVE_NMI 354 bool 355 help 356 The arch provides a low level NMI watchdog. It provides 357 asm/nmi.h, and defines its own arch_touch_nmi_watchdog(). 358 359config HAVE_HARDLOCKUP_DETECTOR_ARCH 360 bool 361 select HAVE_NMI_WATCHDOG 362 help 363 The arch chooses to provide its own hardlockup detector, which is 364 a superset of the HAVE_NMI_WATCHDOG. It also conforms to config 365 interfaces and parameters provided by hardlockup detector subsystem. 366 367config HAVE_PERF_REGS 368 bool 369 help 370 Support selective register dumps for perf events. This includes 371 bit-mapping of each registers and a unique architecture id. 372 373config HAVE_PERF_USER_STACK_DUMP 374 bool 375 help 376 Support user stack dumps for perf event samples. This needs 377 access to the user stack pointer which is not unified across 378 architectures. 379 380config HAVE_ARCH_JUMP_LABEL 381 bool 382 383config HAVE_ARCH_JUMP_LABEL_RELATIVE 384 bool 385 386config HAVE_RCU_TABLE_FREE 387 bool 388 389config HAVE_RCU_TABLE_NO_INVALIDATE 390 bool 391 392config HAVE_MMU_GATHER_PAGE_SIZE 393 bool 394 395config HAVE_MMU_GATHER_NO_GATHER 396 bool 397 398config ARCH_HAVE_NMI_SAFE_CMPXCHG 399 bool 400 401config HAVE_ALIGNED_STRUCT_PAGE 402 bool 403 help 404 This makes sure that struct pages are double word aligned and that 405 e.g. the SLUB allocator can perform double word atomic operations 406 on a struct page for better performance. However selecting this 407 might increase the size of a struct page by a word. 408 409config HAVE_CMPXCHG_LOCAL 410 bool 411 412config HAVE_CMPXCHG_DOUBLE 413 bool 414 415config ARCH_WEAK_RELEASE_ACQUIRE 416 bool 417 418config ARCH_WANT_IPC_PARSE_VERSION 419 bool 420 421config ARCH_WANT_COMPAT_IPC_PARSE_VERSION 422 bool 423 424config ARCH_WANT_OLD_COMPAT_IPC 425 select ARCH_WANT_COMPAT_IPC_PARSE_VERSION 426 bool 427 428config HAVE_ARCH_SECCOMP_FILTER 429 bool 430 help 431 An arch should select this symbol if it provides all of these things: 432 - syscall_get_arch() 433 - syscall_get_arguments() 434 - syscall_rollback() 435 - syscall_set_return_value() 436 - SIGSYS siginfo_t support 437 - secure_computing is called from a ptrace_event()-safe context 438 - secure_computing return value is checked and a return value of -1 439 results in the system call being skipped immediately. 440 - seccomp syscall wired up 441 442config SECCOMP_FILTER 443 def_bool y 444 depends on HAVE_ARCH_SECCOMP_FILTER && SECCOMP && NET 445 help 446 Enable tasks to build secure computing environments defined 447 in terms of Berkeley Packet Filter programs which implement 448 task-defined system call filtering polices. 449 450 See Documentation/userspace-api/seccomp_filter.rst for details. 451 452config HAVE_ARCH_STACKLEAK 453 bool 454 help 455 An architecture should select this if it has the code which 456 fills the used part of the kernel stack with the STACKLEAK_POISON 457 value before returning from system calls. 458 459config HAVE_STACKPROTECTOR 460 bool 461 help 462 An arch should select this symbol if: 463 - it has implemented a stack canary (e.g. __stack_chk_guard) 464 465config CC_HAS_STACKPROTECTOR_NONE 466 def_bool $(cc-option,-fno-stack-protector) 467 468config STACKPROTECTOR 469 bool "Stack Protector buffer overflow detection" 470 depends on HAVE_STACKPROTECTOR 471 depends on $(cc-option,-fstack-protector) 472 default y 473 help 474 This option turns on the "stack-protector" GCC feature. This 475 feature puts, at the beginning of functions, a canary value on 476 the stack just before the return address, and validates 477 the value just before actually returning. Stack based buffer 478 overflows (that need to overwrite this return address) now also 479 overwrite the canary, which gets detected and the attack is then 480 neutralized via a kernel panic. 481 482 Functions will have the stack-protector canary logic added if they 483 have an 8-byte or larger character array on the stack. 484 485 This feature requires gcc version 4.2 or above, or a distribution 486 gcc with the feature backported ("-fstack-protector"). 487 488 On an x86 "defconfig" build, this feature adds canary checks to 489 about 3% of all kernel functions, which increases kernel code size 490 by about 0.3%. 491 492config STACKPROTECTOR_STRONG 493 bool "Strong Stack Protector" 494 depends on STACKPROTECTOR 495 depends on $(cc-option,-fstack-protector-strong) 496 default y 497 help 498 Functions will have the stack-protector canary logic added in any 499 of the following conditions: 500 501 - local variable's address used as part of the right hand side of an 502 assignment or function argument 503 - local variable is an array (or union containing an array), 504 regardless of array type or length 505 - uses register local variables 506 507 This feature requires gcc version 4.9 or above, or a distribution 508 gcc with the feature backported ("-fstack-protector-strong"). 509 510 On an x86 "defconfig" build, this feature adds canary checks to 511 about 20% of all kernel functions, which increases the kernel code 512 size by about 2%. 513 514config HAVE_ARCH_WITHIN_STACK_FRAMES 515 bool 516 help 517 An architecture should select this if it can walk the kernel stack 518 frames to determine if an object is part of either the arguments 519 or local variables (i.e. that it excludes saved return addresses, 520 and similar) by implementing an inline arch_within_stack_frames(), 521 which is used by CONFIG_HARDENED_USERCOPY. 522 523config HAVE_CONTEXT_TRACKING 524 bool 525 help 526 Provide kernel/user boundaries probes necessary for subsystems 527 that need it, such as userspace RCU extended quiescent state. 528 Syscalls need to be wrapped inside user_exit()-user_enter() through 529 the slow path using TIF_NOHZ flag. Exceptions handlers must be 530 wrapped as well. Irqs are already protected inside 531 rcu_irq_enter/rcu_irq_exit() but preemption or signal handling on 532 irq exit still need to be protected. 533 534config HAVE_VIRT_CPU_ACCOUNTING 535 bool 536 537config ARCH_HAS_SCALED_CPUTIME 538 bool 539 540config HAVE_VIRT_CPU_ACCOUNTING_GEN 541 bool 542 default y if 64BIT 543 help 544 With VIRT_CPU_ACCOUNTING_GEN, cputime_t becomes 64-bit. 545 Before enabling this option, arch code must be audited 546 to ensure there are no races in concurrent read/write of 547 cputime_t. For example, reading/writing 64-bit cputime_t on 548 some 32-bit arches may require multiple accesses, so proper 549 locking is needed to protect against concurrent accesses. 550 551 552config HAVE_IRQ_TIME_ACCOUNTING 553 bool 554 help 555 Archs need to ensure they use a high enough resolution clock to 556 support irq time accounting and then call enable_sched_clock_irqtime(). 557 558config HAVE_MOVE_PMD 559 bool 560 help 561 Archs that select this are able to move page tables at the PMD level. 562 563config HAVE_ARCH_TRANSPARENT_HUGEPAGE 564 bool 565 566config HAVE_ARCH_TRANSPARENT_HUGEPAGE_PUD 567 bool 568 569config HAVE_ARCH_HUGE_VMAP 570 bool 571 572config ARCH_WANT_HUGE_PMD_SHARE 573 bool 574 575config HAVE_ARCH_SOFT_DIRTY 576 bool 577 578config HAVE_MOD_ARCH_SPECIFIC 579 bool 580 help 581 The arch uses struct mod_arch_specific to store data. Many arches 582 just need a simple module loader without arch specific data - those 583 should not enable this. 584 585config MODULES_USE_ELF_RELA 586 bool 587 help 588 Modules only use ELF RELA relocations. Modules with ELF REL 589 relocations will give an error. 590 591config MODULES_USE_ELF_REL 592 bool 593 help 594 Modules only use ELF REL relocations. Modules with ELF RELA 595 relocations will give an error. 596 597config HAVE_IRQ_EXIT_ON_IRQ_STACK 598 bool 599 help 600 Architecture doesn't only execute the irq handler on the irq stack 601 but also irq_exit(). This way we can process softirqs on this irq 602 stack instead of switching to a new one when we call __do_softirq() 603 in the end of an hardirq. 604 This spares a stack switch and improves cache usage on softirq 605 processing. 606 607config PGTABLE_LEVELS 608 int 609 default 2 610 611config ARCH_HAS_ELF_RANDOMIZE 612 bool 613 help 614 An architecture supports choosing randomized locations for 615 stack, mmap, brk, and ET_DYN. Defined functions: 616 - arch_mmap_rnd() 617 - arch_randomize_brk() 618 619config HAVE_ARCH_MMAP_RND_BITS 620 bool 621 help 622 An arch should select this symbol if it supports setting a variable 623 number of bits for use in establishing the base address for mmap 624 allocations, has MMU enabled and provides values for both: 625 - ARCH_MMAP_RND_BITS_MIN 626 - ARCH_MMAP_RND_BITS_MAX 627 628config HAVE_EXIT_THREAD 629 bool 630 help 631 An architecture implements exit_thread. 632 633config ARCH_MMAP_RND_BITS_MIN 634 int 635 636config ARCH_MMAP_RND_BITS_MAX 637 int 638 639config ARCH_MMAP_RND_BITS_DEFAULT 640 int 641 642config ARCH_MMAP_RND_BITS 643 int "Number of bits to use for ASLR of mmap base address" if EXPERT 644 range ARCH_MMAP_RND_BITS_MIN ARCH_MMAP_RND_BITS_MAX 645 default ARCH_MMAP_RND_BITS_DEFAULT if ARCH_MMAP_RND_BITS_DEFAULT 646 default ARCH_MMAP_RND_BITS_MIN 647 depends on HAVE_ARCH_MMAP_RND_BITS 648 help 649 This value can be used to select the number of bits to use to 650 determine the random offset to the base address of vma regions 651 resulting from mmap allocations. This value will be bounded 652 by the architecture's minimum and maximum supported values. 653 654 This value can be changed after boot using the 655 /proc/sys/vm/mmap_rnd_bits tunable 656 657config HAVE_ARCH_MMAP_RND_COMPAT_BITS 658 bool 659 help 660 An arch should select this symbol if it supports running applications 661 in compatibility mode, supports setting a variable number of bits for 662 use in establishing the base address for mmap allocations, has MMU 663 enabled and provides values for both: 664 - ARCH_MMAP_RND_COMPAT_BITS_MIN 665 - ARCH_MMAP_RND_COMPAT_BITS_MAX 666 667config ARCH_MMAP_RND_COMPAT_BITS_MIN 668 int 669 670config ARCH_MMAP_RND_COMPAT_BITS_MAX 671 int 672 673config ARCH_MMAP_RND_COMPAT_BITS_DEFAULT 674 int 675 676config ARCH_MMAP_RND_COMPAT_BITS 677 int "Number of bits to use for ASLR of mmap base address for compatible applications" if EXPERT 678 range ARCH_MMAP_RND_COMPAT_BITS_MIN ARCH_MMAP_RND_COMPAT_BITS_MAX 679 default ARCH_MMAP_RND_COMPAT_BITS_DEFAULT if ARCH_MMAP_RND_COMPAT_BITS_DEFAULT 680 default ARCH_MMAP_RND_COMPAT_BITS_MIN 681 depends on HAVE_ARCH_MMAP_RND_COMPAT_BITS 682 help 683 This value can be used to select the number of bits to use to 684 determine the random offset to the base address of vma regions 685 resulting from mmap allocations for compatible applications This 686 value will be bounded by the architecture's minimum and maximum 687 supported values. 688 689 This value can be changed after boot using the 690 /proc/sys/vm/mmap_rnd_compat_bits tunable 691 692config HAVE_ARCH_COMPAT_MMAP_BASES 693 bool 694 help 695 This allows 64bit applications to invoke 32-bit mmap() syscall 696 and vice-versa 32-bit applications to call 64-bit mmap(). 697 Required for applications doing different bitness syscalls. 698 699config HAVE_COPY_THREAD_TLS 700 bool 701 help 702 Architecture provides copy_thread_tls to accept tls argument via 703 normal C parameter passing, rather than extracting the syscall 704 argument from pt_regs. 705 706config HAVE_STACK_VALIDATION 707 bool 708 help 709 Architecture supports the 'objtool check' host tool command, which 710 performs compile-time stack metadata validation. 711 712config HAVE_RELIABLE_STACKTRACE 713 bool 714 help 715 Architecture has a save_stack_trace_tsk_reliable() function which 716 only returns a stack trace if it can guarantee the trace is reliable. 717 718config HAVE_ARCH_HASH 719 bool 720 default n 721 help 722 If this is set, the architecture provides an <asm/hash.h> 723 file which provides platform-specific implementations of some 724 functions in <linux/hash.h> or fs/namei.c. 725 726config HAVE_ARCH_NVRAM_OPS 727 bool 728 729config ISA_BUS_API 730 def_bool ISA 731 732# 733# ABI hall of shame 734# 735config CLONE_BACKWARDS 736 bool 737 help 738 Architecture has tls passed as the 4th argument of clone(2), 739 not the 5th one. 740 741config CLONE_BACKWARDS2 742 bool 743 help 744 Architecture has the first two arguments of clone(2) swapped. 745 746config CLONE_BACKWARDS3 747 bool 748 help 749 Architecture has tls passed as the 3rd argument of clone(2), 750 not the 5th one. 751 752config ODD_RT_SIGACTION 753 bool 754 help 755 Architecture has unusual rt_sigaction(2) arguments 756 757config OLD_SIGSUSPEND 758 bool 759 help 760 Architecture has old sigsuspend(2) syscall, of one-argument variety 761 762config OLD_SIGSUSPEND3 763 bool 764 help 765 Even weirder antique ABI - three-argument sigsuspend(2) 766 767config OLD_SIGACTION 768 bool 769 help 770 Architecture has old sigaction(2) syscall. Nope, not the same 771 as OLD_SIGSUSPEND | OLD_SIGSUSPEND3 - alpha has sigsuspend(2), 772 but fairly different variant of sigaction(2), thanks to OSF/1 773 compatibility... 774 775config COMPAT_OLD_SIGACTION 776 bool 777 778config 64BIT_TIME 779 def_bool y 780 help 781 This should be selected by all architectures that need to support 782 new system calls with a 64-bit time_t. This is relevant on all 32-bit 783 architectures, and 64-bit architectures as part of compat syscall 784 handling. 785 786config COMPAT_32BIT_TIME 787 def_bool !64BIT || COMPAT 788 help 789 This enables 32 bit time_t support in addition to 64 bit time_t support. 790 This is relevant on all 32-bit architectures, and 64-bit architectures 791 as part of compat syscall handling. 792 793config ARCH_NO_COHERENT_DMA_MMAP 794 bool 795 796config ARCH_NO_PREEMPT 797 bool 798 799config ARCH_SUPPORTS_RT 800 bool 801 802config CPU_NO_EFFICIENT_FFS 803 def_bool n 804 805config HAVE_ARCH_VMAP_STACK 806 def_bool n 807 help 808 An arch should select this symbol if it can support kernel stacks 809 in vmalloc space. This means: 810 811 - vmalloc space must be large enough to hold many kernel stacks. 812 This may rule out many 32-bit architectures. 813 814 - Stacks in vmalloc space need to work reliably. For example, if 815 vmap page tables are created on demand, either this mechanism 816 needs to work while the stack points to a virtual address with 817 unpopulated page tables or arch code (switch_to() and switch_mm(), 818 most likely) needs to ensure that the stack's page table entries 819 are populated before running on a possibly unpopulated stack. 820 821 - If the stack overflows into a guard page, something reasonable 822 should happen. The definition of "reasonable" is flexible, but 823 instantly rebooting without logging anything would be unfriendly. 824 825config VMAP_STACK 826 default y 827 bool "Use a virtually-mapped stack" 828 depends on HAVE_ARCH_VMAP_STACK && !KASAN 829 ---help--- 830 Enable this if you want the use virtually-mapped kernel stacks 831 with guard pages. This causes kernel stack overflows to be 832 caught immediately rather than causing difficult-to-diagnose 833 corruption. 834 835 This is presently incompatible with KASAN because KASAN expects 836 the stack to map directly to the KASAN shadow map using a formula 837 that is incorrect if the stack is in vmalloc space. 838 839config ARCH_OPTIONAL_KERNEL_RWX 840 def_bool n 841 842config ARCH_OPTIONAL_KERNEL_RWX_DEFAULT 843 def_bool n 844 845config ARCH_HAS_STRICT_KERNEL_RWX 846 def_bool n 847 848config STRICT_KERNEL_RWX 849 bool "Make kernel text and rodata read-only" if ARCH_OPTIONAL_KERNEL_RWX 850 depends on ARCH_HAS_STRICT_KERNEL_RWX 851 default !ARCH_OPTIONAL_KERNEL_RWX || ARCH_OPTIONAL_KERNEL_RWX_DEFAULT 852 help 853 If this is set, kernel text and rodata memory will be made read-only, 854 and non-text memory will be made non-executable. This provides 855 protection against certain security exploits (e.g. executing the heap 856 or modifying text) 857 858 These features are considered standard security practice these days. 859 You should say Y here in almost all cases. 860 861config ARCH_HAS_STRICT_MODULE_RWX 862 def_bool n 863 864config STRICT_MODULE_RWX 865 bool "Set loadable kernel module data as NX and text as RO" if ARCH_OPTIONAL_KERNEL_RWX 866 depends on ARCH_HAS_STRICT_MODULE_RWX && MODULES 867 default !ARCH_OPTIONAL_KERNEL_RWX || ARCH_OPTIONAL_KERNEL_RWX_DEFAULT 868 help 869 If this is set, module text and rodata memory will be made read-only, 870 and non-text memory will be made non-executable. This provides 871 protection against certain security exploits (e.g. writing to text) 872 873# select if the architecture provides an asm/dma-direct.h header 874config ARCH_HAS_PHYS_TO_DMA 875 bool 876 877config ARCH_HAS_REFCOUNT 878 bool 879 help 880 An architecture selects this when it has implemented refcount_t 881 using open coded assembly primitives that provide an optimized 882 refcount_t implementation, possibly at the expense of some full 883 refcount state checks of CONFIG_REFCOUNT_FULL=y. 884 885 The refcount overflow check behavior, however, must be retained. 886 Catching overflows is the primary security concern for protecting 887 against bugs in reference counts. 888 889config REFCOUNT_FULL 890 bool "Perform full reference count validation at the expense of speed" 891 help 892 Enabling this switches the refcounting infrastructure from a fast 893 unchecked atomic_t implementation to a fully state checked 894 implementation, which can be (slightly) slower but provides protections 895 against various use-after-free conditions that can be used in 896 security flaw exploits. 897 898config HAVE_ARCH_COMPILER_H 899 bool 900 help 901 An architecture can select this if it provides an 902 asm/compiler.h header that should be included after 903 linux/compiler-*.h in order to override macro definitions that those 904 headers generally provide. 905 906config HAVE_ARCH_PREL32_RELOCATIONS 907 bool 908 help 909 May be selected by an architecture if it supports place-relative 910 32-bit relocations, both in the toolchain and in the module loader, 911 in which case relative references can be used in special sections 912 for PCI fixup, initcalls etc which are only half the size on 64 bit 913 architectures, and don't require runtime relocation on relocatable 914 kernels. 915 916config ARCH_USE_MEMREMAP_PROT 917 bool 918 919config LOCK_EVENT_COUNTS 920 bool "Locking event counts collection" 921 depends on DEBUG_FS 922 ---help--- 923 Enable light-weight counting of various locking related events 924 in the system with minimal performance impact. This reduces 925 the chance of application behavior change because of timing 926 differences. The counts are reported via debugfs. 927 928source "kernel/gcov/Kconfig" 929 930source "scripts/gcc-plugins/Kconfig" 931 932endmenu 933