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 MMU_GATHER_TABLE_FREE 397 bool 398 399config MMU_GATHER_RCU_TABLE_FREE 400 bool 401 select MMU_GATHER_TABLE_FREE 402 403config MMU_GATHER_PAGE_SIZE 404 bool 405 406config MMU_GATHER_NO_RANGE 407 bool 408 409config MMU_GATHER_NO_GATHER 410 bool 411 depends on MMU_GATHER_TABLE_FREE 412 413config ARCH_HAVE_NMI_SAFE_CMPXCHG 414 bool 415 416config HAVE_ALIGNED_STRUCT_PAGE 417 bool 418 help 419 This makes sure that struct pages are double word aligned and that 420 e.g. the SLUB allocator can perform double word atomic operations 421 on a struct page for better performance. However selecting this 422 might increase the size of a struct page by a word. 423 424config HAVE_CMPXCHG_LOCAL 425 bool 426 427config HAVE_CMPXCHG_DOUBLE 428 bool 429 430config ARCH_WEAK_RELEASE_ACQUIRE 431 bool 432 433config ARCH_WANT_IPC_PARSE_VERSION 434 bool 435 436config ARCH_WANT_COMPAT_IPC_PARSE_VERSION 437 bool 438 439config ARCH_WANT_OLD_COMPAT_IPC 440 select ARCH_WANT_COMPAT_IPC_PARSE_VERSION 441 bool 442 443config HAVE_ARCH_SECCOMP_FILTER 444 bool 445 help 446 An arch should select this symbol if it provides all of these things: 447 - syscall_get_arch() 448 - syscall_get_arguments() 449 - syscall_rollback() 450 - syscall_set_return_value() 451 - SIGSYS siginfo_t support 452 - secure_computing is called from a ptrace_event()-safe context 453 - secure_computing return value is checked and a return value of -1 454 results in the system call being skipped immediately. 455 - seccomp syscall wired up 456 457config SECCOMP_FILTER 458 def_bool y 459 depends on HAVE_ARCH_SECCOMP_FILTER && SECCOMP && NET 460 help 461 Enable tasks to build secure computing environments defined 462 in terms of Berkeley Packet Filter programs which implement 463 task-defined system call filtering polices. 464 465 See Documentation/userspace-api/seccomp_filter.rst for details. 466 467config HAVE_ARCH_STACKLEAK 468 bool 469 help 470 An architecture should select this if it has the code which 471 fills the used part of the kernel stack with the STACKLEAK_POISON 472 value before returning from system calls. 473 474config HAVE_STACKPROTECTOR 475 bool 476 help 477 An arch should select this symbol if: 478 - it has implemented a stack canary (e.g. __stack_chk_guard) 479 480config CC_HAS_STACKPROTECTOR_NONE 481 def_bool $(cc-option,-fno-stack-protector) 482 483config STACKPROTECTOR 484 bool "Stack Protector buffer overflow detection" 485 depends on HAVE_STACKPROTECTOR 486 depends on $(cc-option,-fstack-protector) 487 default y 488 help 489 This option turns on the "stack-protector" GCC feature. This 490 feature puts, at the beginning of functions, a canary value on 491 the stack just before the return address, and validates 492 the value just before actually returning. Stack based buffer 493 overflows (that need to overwrite this return address) now also 494 overwrite the canary, which gets detected and the attack is then 495 neutralized via a kernel panic. 496 497 Functions will have the stack-protector canary logic added if they 498 have an 8-byte or larger character array on the stack. 499 500 This feature requires gcc version 4.2 or above, or a distribution 501 gcc with the feature backported ("-fstack-protector"). 502 503 On an x86 "defconfig" build, this feature adds canary checks to 504 about 3% of all kernel functions, which increases kernel code size 505 by about 0.3%. 506 507config STACKPROTECTOR_STRONG 508 bool "Strong Stack Protector" 509 depends on STACKPROTECTOR 510 depends on $(cc-option,-fstack-protector-strong) 511 default y 512 help 513 Functions will have the stack-protector canary logic added in any 514 of the following conditions: 515 516 - local variable's address used as part of the right hand side of an 517 assignment or function argument 518 - local variable is an array (or union containing an array), 519 regardless of array type or length 520 - uses register local variables 521 522 This feature requires gcc version 4.9 or above, or a distribution 523 gcc with the feature backported ("-fstack-protector-strong"). 524 525 On an x86 "defconfig" build, this feature adds canary checks to 526 about 20% of all kernel functions, which increases the kernel code 527 size by about 2%. 528 529config HAVE_ARCH_WITHIN_STACK_FRAMES 530 bool 531 help 532 An architecture should select this if it can walk the kernel stack 533 frames to determine if an object is part of either the arguments 534 or local variables (i.e. that it excludes saved return addresses, 535 and similar) by implementing an inline arch_within_stack_frames(), 536 which is used by CONFIG_HARDENED_USERCOPY. 537 538config HAVE_CONTEXT_TRACKING 539 bool 540 help 541 Provide kernel/user boundaries probes necessary for subsystems 542 that need it, such as userspace RCU extended quiescent state. 543 Syscalls need to be wrapped inside user_exit()-user_enter() through 544 the slow path using TIF_NOHZ flag. Exceptions handlers must be 545 wrapped as well. Irqs are already protected inside 546 rcu_irq_enter/rcu_irq_exit() but preemption or signal handling on 547 irq exit still need to be protected. 548 549config HAVE_VIRT_CPU_ACCOUNTING 550 bool 551 552config ARCH_HAS_SCALED_CPUTIME 553 bool 554 555config HAVE_VIRT_CPU_ACCOUNTING_GEN 556 bool 557 default y if 64BIT 558 help 559 With VIRT_CPU_ACCOUNTING_GEN, cputime_t becomes 64-bit. 560 Before enabling this option, arch code must be audited 561 to ensure there are no races in concurrent read/write of 562 cputime_t. For example, reading/writing 64-bit cputime_t on 563 some 32-bit arches may require multiple accesses, so proper 564 locking is needed to protect against concurrent accesses. 565 566 567config HAVE_IRQ_TIME_ACCOUNTING 568 bool 569 help 570 Archs need to ensure they use a high enough resolution clock to 571 support irq time accounting and then call enable_sched_clock_irqtime(). 572 573config HAVE_MOVE_PMD 574 bool 575 help 576 Archs that select this are able to move page tables at the PMD level. 577 578config HAVE_ARCH_TRANSPARENT_HUGEPAGE 579 bool 580 581config HAVE_ARCH_TRANSPARENT_HUGEPAGE_PUD 582 bool 583 584config HAVE_ARCH_HUGE_VMAP 585 bool 586 587config ARCH_WANT_HUGE_PMD_SHARE 588 bool 589 590config HAVE_ARCH_SOFT_DIRTY 591 bool 592 593config HAVE_MOD_ARCH_SPECIFIC 594 bool 595 help 596 The arch uses struct mod_arch_specific to store data. Many arches 597 just need a simple module loader without arch specific data - those 598 should not enable this. 599 600config MODULES_USE_ELF_RELA 601 bool 602 help 603 Modules only use ELF RELA relocations. Modules with ELF REL 604 relocations will give an error. 605 606config MODULES_USE_ELF_REL 607 bool 608 help 609 Modules only use ELF REL relocations. Modules with ELF RELA 610 relocations will give an error. 611 612config HAVE_IRQ_EXIT_ON_IRQ_STACK 613 bool 614 help 615 Architecture doesn't only execute the irq handler on the irq stack 616 but also irq_exit(). This way we can process softirqs on this irq 617 stack instead of switching to a new one when we call __do_softirq() 618 in the end of an hardirq. 619 This spares a stack switch and improves cache usage on softirq 620 processing. 621 622config PGTABLE_LEVELS 623 int 624 default 2 625 626config ARCH_HAS_ELF_RANDOMIZE 627 bool 628 help 629 An architecture supports choosing randomized locations for 630 stack, mmap, brk, and ET_DYN. Defined functions: 631 - arch_mmap_rnd() 632 - arch_randomize_brk() 633 634config HAVE_ARCH_MMAP_RND_BITS 635 bool 636 help 637 An arch should select this symbol if it supports setting a variable 638 number of bits for use in establishing the base address for mmap 639 allocations, has MMU enabled and provides values for both: 640 - ARCH_MMAP_RND_BITS_MIN 641 - ARCH_MMAP_RND_BITS_MAX 642 643config HAVE_EXIT_THREAD 644 bool 645 help 646 An architecture implements exit_thread. 647 648config ARCH_MMAP_RND_BITS_MIN 649 int 650 651config ARCH_MMAP_RND_BITS_MAX 652 int 653 654config ARCH_MMAP_RND_BITS_DEFAULT 655 int 656 657config ARCH_MMAP_RND_BITS 658 int "Number of bits to use for ASLR of mmap base address" if EXPERT 659 range ARCH_MMAP_RND_BITS_MIN ARCH_MMAP_RND_BITS_MAX 660 default ARCH_MMAP_RND_BITS_DEFAULT if ARCH_MMAP_RND_BITS_DEFAULT 661 default ARCH_MMAP_RND_BITS_MIN 662 depends on HAVE_ARCH_MMAP_RND_BITS 663 help 664 This value can be used to select the number of bits to use to 665 determine the random offset to the base address of vma regions 666 resulting from mmap allocations. This value will be bounded 667 by the architecture's minimum and maximum supported values. 668 669 This value can be changed after boot using the 670 /proc/sys/vm/mmap_rnd_bits tunable 671 672config HAVE_ARCH_MMAP_RND_COMPAT_BITS 673 bool 674 help 675 An arch should select this symbol if it supports running applications 676 in compatibility mode, supports setting a variable number of bits for 677 use in establishing the base address for mmap allocations, has MMU 678 enabled and provides values for both: 679 - ARCH_MMAP_RND_COMPAT_BITS_MIN 680 - ARCH_MMAP_RND_COMPAT_BITS_MAX 681 682config ARCH_MMAP_RND_COMPAT_BITS_MIN 683 int 684 685config ARCH_MMAP_RND_COMPAT_BITS_MAX 686 int 687 688config ARCH_MMAP_RND_COMPAT_BITS_DEFAULT 689 int 690 691config ARCH_MMAP_RND_COMPAT_BITS 692 int "Number of bits to use for ASLR of mmap base address for compatible applications" if EXPERT 693 range ARCH_MMAP_RND_COMPAT_BITS_MIN ARCH_MMAP_RND_COMPAT_BITS_MAX 694 default ARCH_MMAP_RND_COMPAT_BITS_DEFAULT if ARCH_MMAP_RND_COMPAT_BITS_DEFAULT 695 default ARCH_MMAP_RND_COMPAT_BITS_MIN 696 depends on HAVE_ARCH_MMAP_RND_COMPAT_BITS 697 help 698 This value can be used to select the number of bits to use to 699 determine the random offset to the base address of vma regions 700 resulting from mmap allocations for compatible applications This 701 value will be bounded by the architecture's minimum and maximum 702 supported values. 703 704 This value can be changed after boot using the 705 /proc/sys/vm/mmap_rnd_compat_bits tunable 706 707config HAVE_ARCH_COMPAT_MMAP_BASES 708 bool 709 help 710 This allows 64bit applications to invoke 32-bit mmap() syscall 711 and vice-versa 32-bit applications to call 64-bit mmap(). 712 Required for applications doing different bitness syscalls. 713 714# This allows to use a set of generic functions to determine mmap base 715# address by giving priority to top-down scheme only if the process 716# is not in legacy mode (compat task, unlimited stack size or 717# sysctl_legacy_va_layout). 718# Architecture that selects this option can provide its own version of: 719# - STACK_RND_MASK 720config ARCH_WANT_DEFAULT_TOPDOWN_MMAP_LAYOUT 721 bool 722 depends on MMU 723 select ARCH_HAS_ELF_RANDOMIZE 724 725config HAVE_COPY_THREAD_TLS 726 bool 727 help 728 Architecture provides copy_thread_tls to accept tls argument via 729 normal C parameter passing, rather than extracting the syscall 730 argument from pt_regs. 731 732config HAVE_STACK_VALIDATION 733 bool 734 help 735 Architecture supports the 'objtool check' host tool command, which 736 performs compile-time stack metadata validation. 737 738config HAVE_RELIABLE_STACKTRACE 739 bool 740 help 741 Architecture has a save_stack_trace_tsk_reliable() function which 742 only returns a stack trace if it can guarantee the trace is reliable. 743 744config HAVE_ARCH_HASH 745 bool 746 default n 747 help 748 If this is set, the architecture provides an <asm/hash.h> 749 file which provides platform-specific implementations of some 750 functions in <linux/hash.h> or fs/namei.c. 751 752config HAVE_ARCH_NVRAM_OPS 753 bool 754 755config ISA_BUS_API 756 def_bool ISA 757 758# 759# ABI hall of shame 760# 761config CLONE_BACKWARDS 762 bool 763 help 764 Architecture has tls passed as the 4th argument of clone(2), 765 not the 5th one. 766 767config CLONE_BACKWARDS2 768 bool 769 help 770 Architecture has the first two arguments of clone(2) swapped. 771 772config CLONE_BACKWARDS3 773 bool 774 help 775 Architecture has tls passed as the 3rd argument of clone(2), 776 not the 5th one. 777 778config ODD_RT_SIGACTION 779 bool 780 help 781 Architecture has unusual rt_sigaction(2) arguments 782 783config OLD_SIGSUSPEND 784 bool 785 help 786 Architecture has old sigsuspend(2) syscall, of one-argument variety 787 788config OLD_SIGSUSPEND3 789 bool 790 help 791 Even weirder antique ABI - three-argument sigsuspend(2) 792 793config OLD_SIGACTION 794 bool 795 help 796 Architecture has old sigaction(2) syscall. Nope, not the same 797 as OLD_SIGSUSPEND | OLD_SIGSUSPEND3 - alpha has sigsuspend(2), 798 but fairly different variant of sigaction(2), thanks to OSF/1 799 compatibility... 800 801config COMPAT_OLD_SIGACTION 802 bool 803 804config COMPAT_32BIT_TIME 805 bool "Provide system calls for 32-bit time_t" 806 default !64BIT || COMPAT 807 help 808 This enables 32 bit time_t support in addition to 64 bit time_t support. 809 This is relevant on all 32-bit architectures, and 64-bit architectures 810 as part of compat syscall handling. 811 812config ARCH_NO_PREEMPT 813 bool 814 815config ARCH_SUPPORTS_RT 816 bool 817 818config CPU_NO_EFFICIENT_FFS 819 def_bool n 820 821config HAVE_ARCH_VMAP_STACK 822 def_bool n 823 help 824 An arch should select this symbol if it can support kernel stacks 825 in vmalloc space. This means: 826 827 - vmalloc space must be large enough to hold many kernel stacks. 828 This may rule out many 32-bit architectures. 829 830 - Stacks in vmalloc space need to work reliably. For example, if 831 vmap page tables are created on demand, either this mechanism 832 needs to work while the stack points to a virtual address with 833 unpopulated page tables or arch code (switch_to() and switch_mm(), 834 most likely) needs to ensure that the stack's page table entries 835 are populated before running on a possibly unpopulated stack. 836 837 - If the stack overflows into a guard page, something reasonable 838 should happen. The definition of "reasonable" is flexible, but 839 instantly rebooting without logging anything would be unfriendly. 840 841config VMAP_STACK 842 default y 843 bool "Use a virtually-mapped stack" 844 depends on HAVE_ARCH_VMAP_STACK 845 depends on !KASAN || KASAN_VMALLOC 846 ---help--- 847 Enable this if you want the use virtually-mapped kernel stacks 848 with guard pages. This causes kernel stack overflows to be 849 caught immediately rather than causing difficult-to-diagnose 850 corruption. 851 852 To use this with KASAN, the architecture must support backing 853 virtual mappings with real shadow memory, and KASAN_VMALLOC must 854 be enabled. 855 856config ARCH_OPTIONAL_KERNEL_RWX 857 def_bool n 858 859config ARCH_OPTIONAL_KERNEL_RWX_DEFAULT 860 def_bool n 861 862config ARCH_HAS_STRICT_KERNEL_RWX 863 def_bool n 864 865config STRICT_KERNEL_RWX 866 bool "Make kernel text and rodata read-only" if ARCH_OPTIONAL_KERNEL_RWX 867 depends on ARCH_HAS_STRICT_KERNEL_RWX 868 default !ARCH_OPTIONAL_KERNEL_RWX || ARCH_OPTIONAL_KERNEL_RWX_DEFAULT 869 help 870 If this is set, kernel text and rodata memory will be made read-only, 871 and non-text memory will be made non-executable. This provides 872 protection against certain security exploits (e.g. executing the heap 873 or modifying text) 874 875 These features are considered standard security practice these days. 876 You should say Y here in almost all cases. 877 878config ARCH_HAS_STRICT_MODULE_RWX 879 def_bool n 880 881config STRICT_MODULE_RWX 882 bool "Set loadable kernel module data as NX and text as RO" if ARCH_OPTIONAL_KERNEL_RWX 883 depends on ARCH_HAS_STRICT_MODULE_RWX && MODULES 884 default !ARCH_OPTIONAL_KERNEL_RWX || ARCH_OPTIONAL_KERNEL_RWX_DEFAULT 885 help 886 If this is set, module text and rodata memory will be made read-only, 887 and non-text memory will be made non-executable. This provides 888 protection against certain security exploits (e.g. writing to text) 889 890# select if the architecture provides an asm/dma-direct.h header 891config ARCH_HAS_PHYS_TO_DMA 892 bool 893 894config HAVE_ARCH_COMPILER_H 895 bool 896 help 897 An architecture can select this if it provides an 898 asm/compiler.h header that should be included after 899 linux/compiler-*.h in order to override macro definitions that those 900 headers generally provide. 901 902config HAVE_ARCH_PREL32_RELOCATIONS 903 bool 904 help 905 May be selected by an architecture if it supports place-relative 906 32-bit relocations, both in the toolchain and in the module loader, 907 in which case relative references can be used in special sections 908 for PCI fixup, initcalls etc which are only half the size on 64 bit 909 architectures, and don't require runtime relocation on relocatable 910 kernels. 911 912config ARCH_USE_MEMREMAP_PROT 913 bool 914 915config LOCK_EVENT_COUNTS 916 bool "Locking event counts collection" 917 depends on DEBUG_FS 918 ---help--- 919 Enable light-weight counting of various locking related events 920 in the system with minimal performance impact. This reduces 921 the chance of application behavior change because of timing 922 differences. The counts are reported via debugfs. 923 924# Select if the architecture has support for applying RELR relocations. 925config ARCH_HAS_RELR 926 bool 927 928config RELR 929 bool "Use RELR relocation packing" 930 depends on ARCH_HAS_RELR && TOOLS_SUPPORT_RELR 931 default y 932 help 933 Store the kernel's dynamic relocations in the RELR relocation packing 934 format. Requires a compatible linker (LLD supports this feature), as 935 well as compatible NM and OBJCOPY utilities (llvm-nm and llvm-objcopy 936 are compatible). 937 938config ARCH_HAS_MEM_ENCRYPT 939 bool 940 941config HAVE_SPARSE_SYSCALL_NR 942 bool 943 help 944 An architecture should select this if its syscall numbering is sparse 945 to save space. For example, MIPS architecture has a syscall array with 946 entries at 4000, 5000 and 6000 locations. This option turns on syscall 947 related optimizations for a given architecture. 948 949source "kernel/gcov/Kconfig" 950 951source "scripts/gcc-plugins/Kconfig" 952 953endmenu 954