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 KEXEC_ELF 22 bool 23 24config HAVE_IMA_KEXEC 25 bool 26 27config HOTPLUG_SMT 28 bool 29 30config OPROFILE 31 tristate "OProfile system profiling" 32 depends on PROFILING 33 depends on HAVE_OPROFILE 34 select RING_BUFFER 35 select RING_BUFFER_ALLOW_SWAP 36 help 37 OProfile is a profiling system capable of profiling the 38 whole system, include the kernel, kernel modules, libraries, 39 and applications. 40 41 If unsure, say N. 42 43config OPROFILE_EVENT_MULTIPLEX 44 bool "OProfile multiplexing support (EXPERIMENTAL)" 45 default n 46 depends on OPROFILE && X86 47 help 48 The number of hardware counters is limited. The multiplexing 49 feature enables OProfile to gather more events than counters 50 are provided by the hardware. This is realized by switching 51 between events at a user specified time interval. 52 53 If unsure, say N. 54 55config HAVE_OPROFILE 56 bool 57 58config OPROFILE_NMI_TIMER 59 def_bool y 60 depends on PERF_EVENTS && HAVE_PERF_EVENTS_NMI && !PPC64 61 62config KPROBES 63 bool "Kprobes" 64 depends on MODULES 65 depends on HAVE_KPROBES 66 select KALLSYMS 67 help 68 Kprobes allows you to trap at almost any kernel address and 69 execute a callback function. register_kprobe() establishes 70 a probepoint and specifies the callback. Kprobes is useful 71 for kernel debugging, non-intrusive instrumentation and testing. 72 If in doubt, say "N". 73 74config JUMP_LABEL 75 bool "Optimize very unlikely/likely branches" 76 depends on HAVE_ARCH_JUMP_LABEL 77 depends on CC_HAS_ASM_GOTO 78 help 79 This option enables a transparent branch optimization that 80 makes certain almost-always-true or almost-always-false branch 81 conditions even cheaper to execute within the kernel. 82 83 Certain performance-sensitive kernel code, such as trace points, 84 scheduler functionality, networking code and KVM have such 85 branches and include support for this optimization technique. 86 87 If it is detected that the compiler has support for "asm goto", 88 the kernel will compile such branches with just a nop 89 instruction. When the condition flag is toggled to true, the 90 nop will be converted to a jump instruction to execute the 91 conditional block of instructions. 92 93 This technique lowers overhead and stress on the branch prediction 94 of the processor and generally makes the kernel faster. The update 95 of the condition is slower, but those are always very rare. 96 97 ( On 32-bit x86, the necessary options added to the compiler 98 flags may increase the size of the kernel slightly. ) 99 100config STATIC_KEYS_SELFTEST 101 bool "Static key selftest" 102 depends on JUMP_LABEL 103 help 104 Boot time self-test of the branch patching code. 105 106config OPTPROBES 107 def_bool y 108 depends on KPROBES && HAVE_OPTPROBES 109 select TASKS_RCU if PREEMPTION 110 111config KPROBES_ON_FTRACE 112 def_bool y 113 depends on KPROBES && HAVE_KPROBES_ON_FTRACE 114 depends on DYNAMIC_FTRACE_WITH_REGS 115 help 116 If function tracer is enabled and the arch supports full 117 passing of pt_regs to function tracing, then kprobes can 118 optimize on top of function tracing. 119 120config UPROBES 121 def_bool n 122 depends on ARCH_SUPPORTS_UPROBES 123 help 124 Uprobes is the user-space counterpart to kprobes: they 125 enable instrumentation applications (such as 'perf probe') 126 to establish unintrusive probes in user-space binaries and 127 libraries, by executing handler functions when the probes 128 are hit by user-space applications. 129 130 ( These probes come in the form of single-byte breakpoints, 131 managed by the kernel and kept transparent to the probed 132 application. ) 133 134config HAVE_EFFICIENT_UNALIGNED_ACCESS 135 bool 136 help 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 141 handler.) 142 143 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 148 much. 149 150 See Documentation/unaligned-memory-access.txt for more 151 information on the topic of unaligned memory accesses. 152 153config ARCH_USE_BUILTIN_BSWAP 154 bool 155 help 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. 167 168 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. 171 172config KRETPROBES 173 def_bool y 174 depends on KPROBES && HAVE_KRETPROBES 175 176config USER_RETURN_NOTIFIER 177 bool 178 depends on HAVE_USER_RETURN_NOTIFIER 179 help 180 Provide a kernel-internal notification when a cpu is about to 181 switch to user mode. 182 183config HAVE_IOREMAP_PROT 184 bool 185 186config HAVE_KPROBES 187 bool 188 189config HAVE_KRETPROBES 190 bool 191 192config HAVE_OPTPROBES 193 bool 194 195config HAVE_KPROBES_ON_FTRACE 196 bool 197 198config HAVE_FUNCTION_ERROR_INJECTION 199 bool 200 201config HAVE_NMI 202 bool 203 204# 205# An arch should select this if it provides all these things: 206# 207# task_pt_regs() in asm/processor.h or asm/ptrace.h 208# arch_has_single_step() if there is hardware single-step support 209# arch_has_block_step() if there is hardware block-step support 210# asm/syscall.h supplying asm-generic/syscall.h interface 211# linux/regset.h user_regset interfaces 212# CORE_DUMP_USE_REGSET #define'd in linux/elf.h 213# TIF_SYSCALL_TRACE calls tracehook_report_syscall_{entry,exit} 214# TIF_NOTIFY_RESUME calls tracehook_notify_resume() 215# signal delivery calls tracehook_signal_handler() 216# 217config HAVE_ARCH_TRACEHOOK 218 bool 219 220config HAVE_DMA_CONTIGUOUS 221 bool 222 223config GENERIC_SMP_IDLE_THREAD 224 bool 225 226config GENERIC_IDLE_POLL_SETUP 227 bool 228 229config ARCH_HAS_FORTIFY_SOURCE 230 bool 231 help 232 An architecture should select this when it can successfully 233 build and run with CONFIG_FORTIFY_SOURCE. 234 235# 236# Select if the arch provides a historic keepinit alias for the retain_initrd 237# command line option 238# 239config ARCH_HAS_KEEPINITRD 240 bool 241 242# Select if arch has all set_memory_ro/rw/x/nx() functions in asm/cacheflush.h 243config ARCH_HAS_SET_MEMORY 244 bool 245 246# Select if arch has all set_direct_map_invalid/default() functions 247config ARCH_HAS_SET_DIRECT_MAP 248 bool 249 250# 251# Select if arch has an uncached kernel segment and provides the 252# uncached_kernel_address / cached_kernel_address symbols to use it 253# 254config ARCH_HAS_UNCACHED_SEGMENT 255 select ARCH_HAS_DMA_PREP_COHERENT 256 bool 257 258# Select if arch init_task must go in the __init_task_data section 259config ARCH_TASK_STRUCT_ON_STACK 260 bool 261 262# Select if arch has its private alloc_task_struct() function 263config ARCH_TASK_STRUCT_ALLOCATOR 264 bool 265 266config HAVE_ARCH_THREAD_STRUCT_WHITELIST 267 bool 268 depends on !ARCH_TASK_STRUCT_ALLOCATOR 269 help 270 An architecture should select this to provide hardened usercopy 271 knowledge about what region of the thread_struct should be 272 whitelisted for copying to userspace. Normally this is only the 273 FPU registers. Specifically, arch_thread_struct_whitelist() 274 should be implemented. Without this, the entire thread_struct 275 field in task_struct will be left whitelisted. 276 277# Select if arch has its private alloc_thread_stack() function 278config ARCH_THREAD_STACK_ALLOCATOR 279 bool 280 281# Select if arch wants to size task_struct dynamically via arch_task_struct_size: 282config ARCH_WANTS_DYNAMIC_TASK_STRUCT 283 bool 284 285config ARCH_32BIT_OFF_T 286 bool 287 depends on !64BIT 288 help 289 All new 32-bit architectures should have 64-bit off_t type on 290 userspace side which corresponds to the loff_t kernel type. This 291 is the requirement for modern ABIs. Some existing architectures 292 still support 32-bit off_t. This option is enabled for all such 293 architectures explicitly. 294 295config HAVE_ASM_MODVERSIONS 296 bool 297 help 298 This symbol should be selected by an architecure if it provides 299 <asm/asm-prototypes.h> to support the module versioning for symbols 300 exported from assembly code. 301 302config HAVE_REGS_AND_STACK_ACCESS_API 303 bool 304 help 305 This symbol should be selected by an architecure if it supports 306 the API needed to access registers and stack entries from pt_regs, 307 declared in asm/ptrace.h 308 For example the kprobes-based event tracer needs this API. 309 310config HAVE_RSEQ 311 bool 312 depends on HAVE_REGS_AND_STACK_ACCESS_API 313 help 314 This symbol should be selected by an architecture if it 315 supports an implementation of restartable sequences. 316 317config HAVE_FUNCTION_ARG_ACCESS_API 318 bool 319 help 320 This symbol should be selected by an architecure if it supports 321 the API needed to access function arguments from pt_regs, 322 declared in asm/ptrace.h 323 324config HAVE_CLK 325 bool 326 help 327 The <linux/clk.h> calls support software clock gating and 328 thus are a key power management tool on many systems. 329 330config HAVE_HW_BREAKPOINT 331 bool 332 depends on PERF_EVENTS 333 334config HAVE_MIXED_BREAKPOINTS_REGS 335 bool 336 depends on HAVE_HW_BREAKPOINT 337 help 338 Depending on the arch implementation of hardware breakpoints, 339 some of them have separate registers for data and instruction 340 breakpoints addresses, others have mixed registers to store 341 them but define the access type in a control register. 342 Select this option if your arch implements breakpoints under the 343 latter fashion. 344 345config HAVE_USER_RETURN_NOTIFIER 346 bool 347 348config HAVE_PERF_EVENTS_NMI 349 bool 350 help 351 System hardware can generate an NMI using the perf event 352 subsystem. Also has support for calculating CPU cycle events 353 to determine how many clock cycles in a given period. 354 355config HAVE_HARDLOCKUP_DETECTOR_PERF 356 bool 357 depends on HAVE_PERF_EVENTS_NMI 358 help 359 The arch chooses to use the generic perf-NMI-based hardlockup 360 detector. Must define HAVE_PERF_EVENTS_NMI. 361 362config HAVE_NMI_WATCHDOG 363 depends on HAVE_NMI 364 bool 365 help 366 The arch provides a low level NMI watchdog. It provides 367 asm/nmi.h, and defines its own arch_touch_nmi_watchdog(). 368 369config HAVE_HARDLOCKUP_DETECTOR_ARCH 370 bool 371 select HAVE_NMI_WATCHDOG 372 help 373 The arch chooses to provide its own hardlockup detector, which is 374 a superset of the HAVE_NMI_WATCHDOG. It also conforms to config 375 interfaces and parameters provided by hardlockup detector subsystem. 376 377config HAVE_PERF_REGS 378 bool 379 help 380 Support selective register dumps for perf events. This includes 381 bit-mapping of each registers and a unique architecture id. 382 383config HAVE_PERF_USER_STACK_DUMP 384 bool 385 help 386 Support user stack dumps for perf event samples. This needs 387 access to the user stack pointer which is not unified across 388 architectures. 389 390config HAVE_ARCH_JUMP_LABEL 391 bool 392 393config HAVE_ARCH_JUMP_LABEL_RELATIVE 394 bool 395 396config HAVE_RCU_TABLE_FREE 397 bool 398 399config HAVE_RCU_TABLE_NO_INVALIDATE 400 bool 401 402config HAVE_MMU_GATHER_PAGE_SIZE 403 bool 404 405config HAVE_MMU_GATHER_NO_GATHER 406 bool 407 408config ARCH_HAVE_NMI_SAFE_CMPXCHG 409 bool 410 411config HAVE_ALIGNED_STRUCT_PAGE 412 bool 413 help 414 This makes sure that struct pages are double word aligned and that 415 e.g. the SLUB allocator can perform double word atomic operations 416 on a struct page for better performance. However selecting this 417 might increase the size of a struct page by a word. 418 419config HAVE_CMPXCHG_LOCAL 420 bool 421 422config HAVE_CMPXCHG_DOUBLE 423 bool 424 425config ARCH_WEAK_RELEASE_ACQUIRE 426 bool 427 428config ARCH_WANT_IPC_PARSE_VERSION 429 bool 430 431config ARCH_WANT_COMPAT_IPC_PARSE_VERSION 432 bool 433 434config ARCH_WANT_OLD_COMPAT_IPC 435 select ARCH_WANT_COMPAT_IPC_PARSE_VERSION 436 bool 437 438config HAVE_ARCH_SECCOMP_FILTER 439 bool 440 help 441 An arch should select this symbol if it provides all of these things: 442 - syscall_get_arch() 443 - syscall_get_arguments() 444 - syscall_rollback() 445 - syscall_set_return_value() 446 - SIGSYS siginfo_t support 447 - secure_computing is called from a ptrace_event()-safe context 448 - secure_computing return value is checked and a return value of -1 449 results in the system call being skipped immediately. 450 - seccomp syscall wired up 451 452config SECCOMP_FILTER 453 def_bool y 454 depends on HAVE_ARCH_SECCOMP_FILTER && SECCOMP && NET 455 help 456 Enable tasks to build secure computing environments defined 457 in terms of Berkeley Packet Filter programs which implement 458 task-defined system call filtering polices. 459 460 See Documentation/userspace-api/seccomp_filter.rst for details. 461 462config HAVE_ARCH_STACKLEAK 463 bool 464 help 465 An architecture should select this if it has the code which 466 fills the used part of the kernel stack with the STACKLEAK_POISON 467 value before returning from system calls. 468 469config HAVE_STACKPROTECTOR 470 bool 471 help 472 An arch should select this symbol if: 473 - it has implemented a stack canary (e.g. __stack_chk_guard) 474 475config CC_HAS_STACKPROTECTOR_NONE 476 def_bool $(cc-option,-fno-stack-protector) 477 478config STACKPROTECTOR 479 bool "Stack Protector buffer overflow detection" 480 depends on HAVE_STACKPROTECTOR 481 depends on $(cc-option,-fstack-protector) 482 default y 483 help 484 This option turns on the "stack-protector" GCC feature. This 485 feature puts, at the beginning of functions, a canary value on 486 the stack just before the return address, and validates 487 the value just before actually returning. Stack based buffer 488 overflows (that need to overwrite this return address) now also 489 overwrite the canary, which gets detected and the attack is then 490 neutralized via a kernel panic. 491 492 Functions will have the stack-protector canary logic added if they 493 have an 8-byte or larger character array on the stack. 494 495 This feature requires gcc version 4.2 or above, or a distribution 496 gcc with the feature backported ("-fstack-protector"). 497 498 On an x86 "defconfig" build, this feature adds canary checks to 499 about 3% of all kernel functions, which increases kernel code size 500 by about 0.3%. 501 502config STACKPROTECTOR_STRONG 503 bool "Strong Stack Protector" 504 depends on STACKPROTECTOR 505 depends on $(cc-option,-fstack-protector-strong) 506 default y 507 help 508 Functions will have the stack-protector canary logic added in any 509 of the following conditions: 510 511 - local variable's address used as part of the right hand side of an 512 assignment or function argument 513 - local variable is an array (or union containing an array), 514 regardless of array type or length 515 - uses register local variables 516 517 This feature requires gcc version 4.9 or above, or a distribution 518 gcc with the feature backported ("-fstack-protector-strong"). 519 520 On an x86 "defconfig" build, this feature adds canary checks to 521 about 20% of all kernel functions, which increases the kernel code 522 size by about 2%. 523 524config HAVE_ARCH_WITHIN_STACK_FRAMES 525 bool 526 help 527 An architecture should select this if it can walk the kernel stack 528 frames to determine if an object is part of either the arguments 529 or local variables (i.e. that it excludes saved return addresses, 530 and similar) by implementing an inline arch_within_stack_frames(), 531 which is used by CONFIG_HARDENED_USERCOPY. 532 533config HAVE_CONTEXT_TRACKING 534 bool 535 help 536 Provide kernel/user boundaries probes necessary for subsystems 537 that need it, such as userspace RCU extended quiescent state. 538 Syscalls need to be wrapped inside user_exit()-user_enter() through 539 the slow path using TIF_NOHZ flag. Exceptions handlers must be 540 wrapped as well. Irqs are already protected inside 541 rcu_irq_enter/rcu_irq_exit() but preemption or signal handling on 542 irq exit still need to be protected. 543 544config HAVE_VIRT_CPU_ACCOUNTING 545 bool 546 547config ARCH_HAS_SCALED_CPUTIME 548 bool 549 550config HAVE_VIRT_CPU_ACCOUNTING_GEN 551 bool 552 default y if 64BIT 553 help 554 With VIRT_CPU_ACCOUNTING_GEN, cputime_t becomes 64-bit. 555 Before enabling this option, arch code must be audited 556 to ensure there are no races in concurrent read/write of 557 cputime_t. For example, reading/writing 64-bit cputime_t on 558 some 32-bit arches may require multiple accesses, so proper 559 locking is needed to protect against concurrent accesses. 560 561 562config HAVE_IRQ_TIME_ACCOUNTING 563 bool 564 help 565 Archs need to ensure they use a high enough resolution clock to 566 support irq time accounting and then call enable_sched_clock_irqtime(). 567 568config HAVE_MOVE_PMD 569 bool 570 help 571 Archs that select this are able to move page tables at the PMD level. 572 573config HAVE_ARCH_TRANSPARENT_HUGEPAGE 574 bool 575 576config HAVE_ARCH_TRANSPARENT_HUGEPAGE_PUD 577 bool 578 579config HAVE_ARCH_HUGE_VMAP 580 bool 581 582config ARCH_WANT_HUGE_PMD_SHARE 583 bool 584 585config HAVE_ARCH_SOFT_DIRTY 586 bool 587 588config HAVE_MOD_ARCH_SPECIFIC 589 bool 590 help 591 The arch uses struct mod_arch_specific to store data. Many arches 592 just need a simple module loader without arch specific data - those 593 should not enable this. 594 595config MODULES_USE_ELF_RELA 596 bool 597 help 598 Modules only use ELF RELA relocations. Modules with ELF REL 599 relocations will give an error. 600 601config MODULES_USE_ELF_REL 602 bool 603 help 604 Modules only use ELF REL relocations. Modules with ELF RELA 605 relocations will give an error. 606 607config HAVE_IRQ_EXIT_ON_IRQ_STACK 608 bool 609 help 610 Architecture doesn't only execute the irq handler on the irq stack 611 but also irq_exit(). This way we can process softirqs on this irq 612 stack instead of switching to a new one when we call __do_softirq() 613 in the end of an hardirq. 614 This spares a stack switch and improves cache usage on softirq 615 processing. 616 617config PGTABLE_LEVELS 618 int 619 default 2 620 621config ARCH_HAS_ELF_RANDOMIZE 622 bool 623 help 624 An architecture supports choosing randomized locations for 625 stack, mmap, brk, and ET_DYN. Defined functions: 626 - arch_mmap_rnd() 627 - arch_randomize_brk() 628 629config HAVE_ARCH_MMAP_RND_BITS 630 bool 631 help 632 An arch should select this symbol if it supports setting a variable 633 number of bits for use in establishing the base address for mmap 634 allocations, has MMU enabled and provides values for both: 635 - ARCH_MMAP_RND_BITS_MIN 636 - ARCH_MMAP_RND_BITS_MAX 637 638config HAVE_EXIT_THREAD 639 bool 640 help 641 An architecture implements exit_thread. 642 643config ARCH_MMAP_RND_BITS_MIN 644 int 645 646config ARCH_MMAP_RND_BITS_MAX 647 int 648 649config ARCH_MMAP_RND_BITS_DEFAULT 650 int 651 652config ARCH_MMAP_RND_BITS 653 int "Number of bits to use for ASLR of mmap base address" if EXPERT 654 range ARCH_MMAP_RND_BITS_MIN ARCH_MMAP_RND_BITS_MAX 655 default ARCH_MMAP_RND_BITS_DEFAULT if ARCH_MMAP_RND_BITS_DEFAULT 656 default ARCH_MMAP_RND_BITS_MIN 657 depends on HAVE_ARCH_MMAP_RND_BITS 658 help 659 This value can be used to select the number of bits to use to 660 determine the random offset to the base address of vma regions 661 resulting from mmap allocations. This value will be bounded 662 by the architecture's minimum and maximum supported values. 663 664 This value can be changed after boot using the 665 /proc/sys/vm/mmap_rnd_bits tunable 666 667config HAVE_ARCH_MMAP_RND_COMPAT_BITS 668 bool 669 help 670 An arch should select this symbol if it supports running applications 671 in compatibility mode, supports setting a variable number of bits for 672 use in establishing the base address for mmap allocations, has MMU 673 enabled and provides values for both: 674 - ARCH_MMAP_RND_COMPAT_BITS_MIN 675 - ARCH_MMAP_RND_COMPAT_BITS_MAX 676 677config ARCH_MMAP_RND_COMPAT_BITS_MIN 678 int 679 680config ARCH_MMAP_RND_COMPAT_BITS_MAX 681 int 682 683config ARCH_MMAP_RND_COMPAT_BITS_DEFAULT 684 int 685 686config ARCH_MMAP_RND_COMPAT_BITS 687 int "Number of bits to use for ASLR of mmap base address for compatible applications" if EXPERT 688 range ARCH_MMAP_RND_COMPAT_BITS_MIN ARCH_MMAP_RND_COMPAT_BITS_MAX 689 default ARCH_MMAP_RND_COMPAT_BITS_DEFAULT if ARCH_MMAP_RND_COMPAT_BITS_DEFAULT 690 default ARCH_MMAP_RND_COMPAT_BITS_MIN 691 depends on HAVE_ARCH_MMAP_RND_COMPAT_BITS 692 help 693 This value can be used to select the number of bits to use to 694 determine the random offset to the base address of vma regions 695 resulting from mmap allocations for compatible applications This 696 value will be bounded by the architecture's minimum and maximum 697 supported values. 698 699 This value can be changed after boot using the 700 /proc/sys/vm/mmap_rnd_compat_bits tunable 701 702config HAVE_ARCH_COMPAT_MMAP_BASES 703 bool 704 help 705 This allows 64bit applications to invoke 32-bit mmap() syscall 706 and vice-versa 32-bit applications to call 64-bit mmap(). 707 Required for applications doing different bitness syscalls. 708 709# This allows to use a set of generic functions to determine mmap base 710# address by giving priority to top-down scheme only if the process 711# is not in legacy mode (compat task, unlimited stack size or 712# sysctl_legacy_va_layout). 713# Architecture that selects this option can provide its own version of: 714# - STACK_RND_MASK 715config ARCH_WANT_DEFAULT_TOPDOWN_MMAP_LAYOUT 716 bool 717 depends on MMU 718 select ARCH_HAS_ELF_RANDOMIZE 719 720config HAVE_COPY_THREAD_TLS 721 bool 722 help 723 Architecture provides copy_thread_tls to accept tls argument via 724 normal C parameter passing, rather than extracting the syscall 725 argument from pt_regs. 726 727config HAVE_STACK_VALIDATION 728 bool 729 help 730 Architecture supports the 'objtool check' host tool command, which 731 performs compile-time stack metadata validation. 732 733config HAVE_RELIABLE_STACKTRACE 734 bool 735 help 736 Architecture has a save_stack_trace_tsk_reliable() function which 737 only returns a stack trace if it can guarantee the trace is reliable. 738 739config HAVE_ARCH_HASH 740 bool 741 default n 742 help 743 If this is set, the architecture provides an <asm/hash.h> 744 file which provides platform-specific implementations of some 745 functions in <linux/hash.h> or fs/namei.c. 746 747config HAVE_ARCH_NVRAM_OPS 748 bool 749 750config ISA_BUS_API 751 def_bool ISA 752 753# 754# ABI hall of shame 755# 756config CLONE_BACKWARDS 757 bool 758 help 759 Architecture has tls passed as the 4th argument of clone(2), 760 not the 5th one. 761 762config CLONE_BACKWARDS2 763 bool 764 help 765 Architecture has the first two arguments of clone(2) swapped. 766 767config CLONE_BACKWARDS3 768 bool 769 help 770 Architecture has tls passed as the 3rd argument of clone(2), 771 not the 5th one. 772 773config ODD_RT_SIGACTION 774 bool 775 help 776 Architecture has unusual rt_sigaction(2) arguments 777 778config OLD_SIGSUSPEND 779 bool 780 help 781 Architecture has old sigsuspend(2) syscall, of one-argument variety 782 783config OLD_SIGSUSPEND3 784 bool 785 help 786 Even weirder antique ABI - three-argument sigsuspend(2) 787 788config OLD_SIGACTION 789 bool 790 help 791 Architecture has old sigaction(2) syscall. Nope, not the same 792 as OLD_SIGSUSPEND | OLD_SIGSUSPEND3 - alpha has sigsuspend(2), 793 but fairly different variant of sigaction(2), thanks to OSF/1 794 compatibility... 795 796config COMPAT_OLD_SIGACTION 797 bool 798 799config 64BIT_TIME 800 def_bool y 801 help 802 This should be selected by all architectures that need to support 803 new system calls with a 64-bit time_t. This is relevant on all 32-bit 804 architectures, and 64-bit architectures as part of compat syscall 805 handling. 806 807config COMPAT_32BIT_TIME 808 def_bool !64BIT || COMPAT 809 help 810 This enables 32 bit time_t support in addition to 64 bit time_t support. 811 This is relevant on all 32-bit architectures, and 64-bit architectures 812 as part of compat syscall handling. 813 814config ARCH_NO_PREEMPT 815 bool 816 817config ARCH_SUPPORTS_RT 818 bool 819 820config CPU_NO_EFFICIENT_FFS 821 def_bool n 822 823config HAVE_ARCH_VMAP_STACK 824 def_bool n 825 help 826 An arch should select this symbol if it can support kernel stacks 827 in vmalloc space. This means: 828 829 - vmalloc space must be large enough to hold many kernel stacks. 830 This may rule out many 32-bit architectures. 831 832 - Stacks in vmalloc space need to work reliably. For example, if 833 vmap page tables are created on demand, either this mechanism 834 needs to work while the stack points to a virtual address with 835 unpopulated page tables or arch code (switch_to() and switch_mm(), 836 most likely) needs to ensure that the stack's page table entries 837 are populated before running on a possibly unpopulated stack. 838 839 - If the stack overflows into a guard page, something reasonable 840 should happen. The definition of "reasonable" is flexible, but 841 instantly rebooting without logging anything would be unfriendly. 842 843config VMAP_STACK 844 default y 845 bool "Use a virtually-mapped stack" 846 depends on HAVE_ARCH_VMAP_STACK && !KASAN 847 ---help--- 848 Enable this if you want the use virtually-mapped kernel stacks 849 with guard pages. This causes kernel stack overflows to be 850 caught immediately rather than causing difficult-to-diagnose 851 corruption. 852 853 This is presently incompatible with KASAN because KASAN expects 854 the stack to map directly to the KASAN shadow map using a formula 855 that is incorrect if the stack is in vmalloc space. 856 857config ARCH_OPTIONAL_KERNEL_RWX 858 def_bool n 859 860config ARCH_OPTIONAL_KERNEL_RWX_DEFAULT 861 def_bool n 862 863config ARCH_HAS_STRICT_KERNEL_RWX 864 def_bool n 865 866config STRICT_KERNEL_RWX 867 bool "Make kernel text and rodata read-only" if ARCH_OPTIONAL_KERNEL_RWX 868 depends on ARCH_HAS_STRICT_KERNEL_RWX 869 default !ARCH_OPTIONAL_KERNEL_RWX || ARCH_OPTIONAL_KERNEL_RWX_DEFAULT 870 help 871 If this is set, kernel text and rodata memory will be made read-only, 872 and non-text memory will be made non-executable. This provides 873 protection against certain security exploits (e.g. executing the heap 874 or modifying text) 875 876 These features are considered standard security practice these days. 877 You should say Y here in almost all cases. 878 879config ARCH_HAS_STRICT_MODULE_RWX 880 def_bool n 881 882config STRICT_MODULE_RWX 883 bool "Set loadable kernel module data as NX and text as RO" if ARCH_OPTIONAL_KERNEL_RWX 884 depends on ARCH_HAS_STRICT_MODULE_RWX && MODULES 885 default !ARCH_OPTIONAL_KERNEL_RWX || ARCH_OPTIONAL_KERNEL_RWX_DEFAULT 886 help 887 If this is set, module text and rodata memory will be made read-only, 888 and non-text memory will be made non-executable. This provides 889 protection against certain security exploits (e.g. writing to text) 890 891# select if the architecture provides an asm/dma-direct.h header 892config ARCH_HAS_PHYS_TO_DMA 893 bool 894 895config ARCH_HAS_REFCOUNT 896 bool 897 help 898 An architecture selects this when it has implemented refcount_t 899 using open coded assembly primitives that provide an optimized 900 refcount_t implementation, possibly at the expense of some full 901 refcount state checks of CONFIG_REFCOUNT_FULL=y. 902 903 The refcount overflow check behavior, however, must be retained. 904 Catching overflows is the primary security concern for protecting 905 against bugs in reference counts. 906 907config REFCOUNT_FULL 908 bool "Perform full reference count validation at the expense of speed" 909 help 910 Enabling this switches the refcounting infrastructure from a fast 911 unchecked atomic_t implementation to a fully state checked 912 implementation, which can be (slightly) slower but provides protections 913 against various use-after-free conditions that can be used in 914 security flaw exploits. 915 916config HAVE_ARCH_COMPILER_H 917 bool 918 help 919 An architecture can select this if it provides an 920 asm/compiler.h header that should be included after 921 linux/compiler-*.h in order to override macro definitions that those 922 headers generally provide. 923 924config HAVE_ARCH_PREL32_RELOCATIONS 925 bool 926 help 927 May be selected by an architecture if it supports place-relative 928 32-bit relocations, both in the toolchain and in the module loader, 929 in which case relative references can be used in special sections 930 for PCI fixup, initcalls etc which are only half the size on 64 bit 931 architectures, and don't require runtime relocation on relocatable 932 kernels. 933 934config ARCH_USE_MEMREMAP_PROT 935 bool 936 937config LOCK_EVENT_COUNTS 938 bool "Locking event counts collection" 939 depends on DEBUG_FS 940 ---help--- 941 Enable light-weight counting of various locking related events 942 in the system with minimal performance impact. This reduces 943 the chance of application behavior change because of timing 944 differences. The counts are reported via debugfs. 945 946# Select if the architecture has support for applying RELR relocations. 947config ARCH_HAS_RELR 948 bool 949 950config RELR 951 bool "Use RELR relocation packing" 952 depends on ARCH_HAS_RELR && TOOLS_SUPPORT_RELR 953 default y 954 help 955 Store the kernel's dynamic relocations in the RELR relocation packing 956 format. Requires a compatible linker (LLD supports this feature), as 957 well as compatible NM and OBJCOPY utilities (llvm-nm and llvm-objcopy 958 are compatible). 959 960config ARCH_HAS_MEM_ENCRYPT 961 bool 962 963source "kernel/gcov/Kconfig" 964 965source "scripts/gcc-plugins/Kconfig" 966 967endmenu 968