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 ARCH_HAS_SUBPAGE_FAULTS 15 bool 16 help 17 Select if the architecture can check permissions at sub-page 18 granularity (e.g. arm64 MTE). The probe_user_*() functions 19 must be implemented. 20 21config HOTPLUG_SMT 22 bool 23 24config SMT_NUM_THREADS_DYNAMIC 25 bool 26 27# Selected by HOTPLUG_CORE_SYNC_DEAD or HOTPLUG_CORE_SYNC_FULL 28config HOTPLUG_CORE_SYNC 29 bool 30 31# Basic CPU dead synchronization selected by architecture 32config HOTPLUG_CORE_SYNC_DEAD 33 bool 34 select HOTPLUG_CORE_SYNC 35 36# Full CPU synchronization with alive state selected by architecture 37config HOTPLUG_CORE_SYNC_FULL 38 bool 39 select HOTPLUG_CORE_SYNC_DEAD if HOTPLUG_CPU 40 select HOTPLUG_CORE_SYNC 41 42config HOTPLUG_SPLIT_STARTUP 43 bool 44 select HOTPLUG_CORE_SYNC_FULL 45 46config HOTPLUG_PARALLEL 47 bool 48 select HOTPLUG_SPLIT_STARTUP 49 50config GENERIC_ENTRY 51 bool 52 53config KPROBES 54 bool "Kprobes" 55 depends on MODULES 56 depends on HAVE_KPROBES 57 select KALLSYMS 58 select TASKS_RCU if PREEMPTION 59 help 60 Kprobes allows you to trap at almost any kernel address and 61 execute a callback function. register_kprobe() establishes 62 a probepoint and specifies the callback. Kprobes is useful 63 for kernel debugging, non-intrusive instrumentation and testing. 64 If in doubt, say "N". 65 66config JUMP_LABEL 67 bool "Optimize very unlikely/likely branches" 68 depends on HAVE_ARCH_JUMP_LABEL 69 select OBJTOOL if HAVE_JUMP_LABEL_HACK 70 help 71 This option enables a transparent branch optimization that 72 makes certain almost-always-true or almost-always-false branch 73 conditions even cheaper to execute within the kernel. 74 75 Certain performance-sensitive kernel code, such as trace points, 76 scheduler functionality, networking code and KVM have such 77 branches and include support for this optimization technique. 78 79 If it is detected that the compiler has support for "asm goto", 80 the kernel will compile such branches with just a nop 81 instruction. When the condition flag is toggled to true, the 82 nop will be converted to a jump instruction to execute the 83 conditional block of instructions. 84 85 This technique lowers overhead and stress on the branch prediction 86 of the processor and generally makes the kernel faster. The update 87 of the condition is slower, but those are always very rare. 88 89 ( On 32-bit x86, the necessary options added to the compiler 90 flags may increase the size of the kernel slightly. ) 91 92config STATIC_KEYS_SELFTEST 93 bool "Static key selftest" 94 depends on JUMP_LABEL 95 help 96 Boot time self-test of the branch patching code. 97 98config STATIC_CALL_SELFTEST 99 bool "Static call selftest" 100 depends on HAVE_STATIC_CALL 101 help 102 Boot time self-test of the call patching code. 103 104config OPTPROBES 105 def_bool y 106 depends on KPROBES && HAVE_OPTPROBES 107 select TASKS_RCU if PREEMPTION 108 109config KPROBES_ON_FTRACE 110 def_bool y 111 depends on KPROBES && HAVE_KPROBES_ON_FTRACE 112 depends on DYNAMIC_FTRACE_WITH_REGS 113 help 114 If function tracer is enabled and the arch supports full 115 passing of pt_regs to function tracing, then kprobes can 116 optimize on top of function tracing. 117 118config UPROBES 119 def_bool n 120 depends on ARCH_SUPPORTS_UPROBES 121 help 122 Uprobes is the user-space counterpart to kprobes: they 123 enable instrumentation applications (such as 'perf probe') 124 to establish unintrusive probes in user-space binaries and 125 libraries, by executing handler functions when the probes 126 are hit by user-space applications. 127 128 ( These probes come in the form of single-byte breakpoints, 129 managed by the kernel and kept transparent to the probed 130 application. ) 131 132config HAVE_64BIT_ALIGNED_ACCESS 133 def_bool 64BIT && !HAVE_EFFICIENT_UNALIGNED_ACCESS 134 help 135 Some architectures require 64 bit accesses to be 64 bit 136 aligned, which also requires structs containing 64 bit values 137 to be 64 bit aligned too. This includes some 32 bit 138 architectures which can do 64 bit accesses, as well as 64 bit 139 architectures without unaligned access. 140 141 This symbol should be selected by an architecture if 64 bit 142 accesses are required to be 64 bit aligned in this way even 143 though it is not a 64 bit architecture. 144 145 See Documentation/core-api/unaligned-memory-access.rst for 146 more information on the topic of unaligned memory accesses. 147 148config HAVE_EFFICIENT_UNALIGNED_ACCESS 149 bool 150 help 151 Some architectures are unable to perform unaligned accesses 152 without the use of get_unaligned/put_unaligned. Others are 153 unable to perform such accesses efficiently (e.g. trap on 154 unaligned access and require fixing it up in the exception 155 handler.) 156 157 This symbol should be selected by an architecture if it can 158 perform unaligned accesses efficiently to allow different 159 code paths to be selected for these cases. Some network 160 drivers, for example, could opt to not fix up alignment 161 problems with received packets if doing so would not help 162 much. 163 164 See Documentation/core-api/unaligned-memory-access.rst for more 165 information on the topic of unaligned memory accesses. 166 167config ARCH_USE_BUILTIN_BSWAP 168 bool 169 help 170 Modern versions of GCC (since 4.4) have builtin functions 171 for handling byte-swapping. Using these, instead of the old 172 inline assembler that the architecture code provides in the 173 __arch_bswapXX() macros, allows the compiler to see what's 174 happening and offers more opportunity for optimisation. In 175 particular, the compiler will be able to combine the byteswap 176 with a nearby load or store and use load-and-swap or 177 store-and-swap instructions if the architecture has them. It 178 should almost *never* result in code which is worse than the 179 hand-coded assembler in <asm/swab.h>. But just in case it 180 does, the use of the builtins is optional. 181 182 Any architecture with load-and-swap or store-and-swap 183 instructions should set this. And it shouldn't hurt to set it 184 on architectures that don't have such instructions. 185 186config KRETPROBES 187 def_bool y 188 depends on KPROBES && (HAVE_KRETPROBES || HAVE_RETHOOK) 189 190config KRETPROBE_ON_RETHOOK 191 def_bool y 192 depends on HAVE_RETHOOK 193 depends on KRETPROBES 194 select RETHOOK 195 196config USER_RETURN_NOTIFIER 197 bool 198 depends on HAVE_USER_RETURN_NOTIFIER 199 help 200 Provide a kernel-internal notification when a cpu is about to 201 switch to user mode. 202 203config HAVE_IOREMAP_PROT 204 bool 205 206config HAVE_KPROBES 207 bool 208 209config HAVE_KRETPROBES 210 bool 211 212config HAVE_OPTPROBES 213 bool 214 215config HAVE_KPROBES_ON_FTRACE 216 bool 217 218config ARCH_CORRECT_STACKTRACE_ON_KRETPROBE 219 bool 220 help 221 Since kretprobes modifies return address on the stack, the 222 stacktrace may see the kretprobe trampoline address instead 223 of correct one. If the architecture stacktrace code and 224 unwinder can adjust such entries, select this configuration. 225 226config HAVE_FUNCTION_ERROR_INJECTION 227 bool 228 229config HAVE_NMI 230 bool 231 232config HAVE_FUNCTION_DESCRIPTORS 233 bool 234 235config TRACE_IRQFLAGS_SUPPORT 236 bool 237 238config TRACE_IRQFLAGS_NMI_SUPPORT 239 bool 240 241# 242# An arch should select this if it provides all these things: 243# 244# task_pt_regs() in asm/processor.h or asm/ptrace.h 245# arch_has_single_step() if there is hardware single-step support 246# arch_has_block_step() if there is hardware block-step support 247# asm/syscall.h supplying asm-generic/syscall.h interface 248# linux/regset.h user_regset interfaces 249# CORE_DUMP_USE_REGSET #define'd in linux/elf.h 250# TIF_SYSCALL_TRACE calls ptrace_report_syscall_{entry,exit} 251# TIF_NOTIFY_RESUME calls resume_user_mode_work() 252# 253config HAVE_ARCH_TRACEHOOK 254 bool 255 256config HAVE_DMA_CONTIGUOUS 257 bool 258 259config GENERIC_SMP_IDLE_THREAD 260 bool 261 262config GENERIC_IDLE_POLL_SETUP 263 bool 264 265config ARCH_HAS_FORTIFY_SOURCE 266 bool 267 help 268 An architecture should select this when it can successfully 269 build and run with CONFIG_FORTIFY_SOURCE. 270 271# 272# Select if the arch provides a historic keepinit alias for the retain_initrd 273# command line option 274# 275config ARCH_HAS_KEEPINITRD 276 bool 277 278# Select if arch has all set_memory_ro/rw/x/nx() functions in asm/cacheflush.h 279config ARCH_HAS_SET_MEMORY 280 bool 281 282# Select if arch has all set_direct_map_invalid/default() functions 283config ARCH_HAS_SET_DIRECT_MAP 284 bool 285 286# 287# Select if the architecture provides the arch_dma_set_uncached symbol to 288# either provide an uncached segment alias for a DMA allocation, or 289# to remap the page tables in place. 290# 291config ARCH_HAS_DMA_SET_UNCACHED 292 bool 293 294# 295# Select if the architectures provides the arch_dma_clear_uncached symbol 296# to undo an in-place page table remap for uncached access. 297# 298config ARCH_HAS_DMA_CLEAR_UNCACHED 299 bool 300 301config ARCH_HAS_CPU_FINALIZE_INIT 302 bool 303 304# The architecture has a per-task state that includes the mm's PASID 305config ARCH_HAS_CPU_PASID 306 bool 307 select IOMMU_MM_DATA 308 309config HAVE_ARCH_THREAD_STRUCT_WHITELIST 310 bool 311 help 312 An architecture should select this to provide hardened usercopy 313 knowledge about what region of the thread_struct should be 314 whitelisted for copying to userspace. Normally this is only the 315 FPU registers. Specifically, arch_thread_struct_whitelist() 316 should be implemented. Without this, the entire thread_struct 317 field in task_struct will be left whitelisted. 318 319# Select if arch wants to size task_struct dynamically via arch_task_struct_size: 320config ARCH_WANTS_DYNAMIC_TASK_STRUCT 321 bool 322 323config ARCH_WANTS_NO_INSTR 324 bool 325 help 326 An architecture should select this if the noinstr macro is being used on 327 functions to denote that the toolchain should avoid instrumenting such 328 functions and is required for correctness. 329 330config ARCH_32BIT_OFF_T 331 bool 332 depends on !64BIT 333 help 334 All new 32-bit architectures should have 64-bit off_t type on 335 userspace side which corresponds to the loff_t kernel type. This 336 is the requirement for modern ABIs. Some existing architectures 337 still support 32-bit off_t. This option is enabled for all such 338 architectures explicitly. 339 340# Selected by 64 bit architectures which have a 32 bit f_tinode in struct ustat 341config ARCH_32BIT_USTAT_F_TINODE 342 bool 343 344config HAVE_ASM_MODVERSIONS 345 bool 346 help 347 This symbol should be selected by an architecture if it provides 348 <asm/asm-prototypes.h> to support the module versioning for symbols 349 exported from assembly code. 350 351config HAVE_REGS_AND_STACK_ACCESS_API 352 bool 353 help 354 This symbol should be selected by an architecture if it supports 355 the API needed to access registers and stack entries from pt_regs, 356 declared in asm/ptrace.h 357 For example the kprobes-based event tracer needs this API. 358 359config HAVE_RSEQ 360 bool 361 depends on HAVE_REGS_AND_STACK_ACCESS_API 362 help 363 This symbol should be selected by an architecture if it 364 supports an implementation of restartable sequences. 365 366config HAVE_RUST 367 bool 368 help 369 This symbol should be selected by an architecture if it 370 supports Rust. 371 372config HAVE_FUNCTION_ARG_ACCESS_API 373 bool 374 help 375 This symbol should be selected by an architecture if it supports 376 the API needed to access function arguments from pt_regs, 377 declared in asm/ptrace.h 378 379config HAVE_HW_BREAKPOINT 380 bool 381 depends on PERF_EVENTS 382 383config HAVE_MIXED_BREAKPOINTS_REGS 384 bool 385 depends on HAVE_HW_BREAKPOINT 386 help 387 Depending on the arch implementation of hardware breakpoints, 388 some of them have separate registers for data and instruction 389 breakpoints addresses, others have mixed registers to store 390 them but define the access type in a control register. 391 Select this option if your arch implements breakpoints under the 392 latter fashion. 393 394config HAVE_USER_RETURN_NOTIFIER 395 bool 396 397config HAVE_PERF_EVENTS_NMI 398 bool 399 help 400 System hardware can generate an NMI using the perf event 401 subsystem. Also has support for calculating CPU cycle events 402 to determine how many clock cycles in a given period. 403 404config HAVE_HARDLOCKUP_DETECTOR_PERF 405 bool 406 depends on HAVE_PERF_EVENTS_NMI 407 help 408 The arch chooses to use the generic perf-NMI-based hardlockup 409 detector. Must define HAVE_PERF_EVENTS_NMI. 410 411config HAVE_HARDLOCKUP_DETECTOR_ARCH 412 bool 413 help 414 The arch provides its own hardlockup detector implementation instead 415 of the generic ones. 416 417 It uses the same command line parameters, and sysctl interface, 418 as the generic hardlockup detectors. 419 420config HAVE_PERF_REGS 421 bool 422 help 423 Support selective register dumps for perf events. This includes 424 bit-mapping of each registers and a unique architecture id. 425 426config HAVE_PERF_USER_STACK_DUMP 427 bool 428 help 429 Support user stack dumps for perf event samples. This needs 430 access to the user stack pointer which is not unified across 431 architectures. 432 433config HAVE_ARCH_JUMP_LABEL 434 bool 435 436config HAVE_ARCH_JUMP_LABEL_RELATIVE 437 bool 438 439config MMU_GATHER_TABLE_FREE 440 bool 441 442config MMU_GATHER_RCU_TABLE_FREE 443 bool 444 select MMU_GATHER_TABLE_FREE 445 446config MMU_GATHER_PAGE_SIZE 447 bool 448 449config MMU_GATHER_NO_RANGE 450 bool 451 select MMU_GATHER_MERGE_VMAS 452 453config MMU_GATHER_NO_FLUSH_CACHE 454 bool 455 456config MMU_GATHER_MERGE_VMAS 457 bool 458 459config MMU_GATHER_NO_GATHER 460 bool 461 depends on MMU_GATHER_TABLE_FREE 462 463config ARCH_WANT_IRQS_OFF_ACTIVATE_MM 464 bool 465 help 466 Temporary select until all architectures can be converted to have 467 irqs disabled over activate_mm. Architectures that do IPI based TLB 468 shootdowns should enable this. 469 470# Use normal mm refcounting for MMU_LAZY_TLB kernel thread references. 471# MMU_LAZY_TLB_REFCOUNT=n can improve the scalability of context switching 472# to/from kernel threads when the same mm is running on a lot of CPUs (a large 473# multi-threaded application), by reducing contention on the mm refcount. 474# 475# This can be disabled if the architecture ensures no CPUs are using an mm as a 476# "lazy tlb" beyond its final refcount (i.e., by the time __mmdrop frees the mm 477# or its kernel page tables). This could be arranged by arch_exit_mmap(), or 478# final exit(2) TLB flush, for example. 479# 480# To implement this, an arch *must*: 481# Ensure the _lazy_tlb variants of mmgrab/mmdrop are used when manipulating 482# the lazy tlb reference of a kthread's ->active_mm (non-arch code has been 483# converted already). 484config MMU_LAZY_TLB_REFCOUNT 485 def_bool y 486 depends on !MMU_LAZY_TLB_SHOOTDOWN 487 488# This option allows MMU_LAZY_TLB_REFCOUNT=n. It ensures no CPUs are using an 489# mm as a lazy tlb beyond its last reference count, by shooting down these 490# users before the mm is deallocated. __mmdrop() first IPIs all CPUs that may 491# be using the mm as a lazy tlb, so that they may switch themselves to using 492# init_mm for their active mm. mm_cpumask(mm) is used to determine which CPUs 493# may be using mm as a lazy tlb mm. 494# 495# To implement this, an arch *must*: 496# - At the time of the final mmdrop of the mm, ensure mm_cpumask(mm) contains 497# at least all possible CPUs in which the mm is lazy. 498# - It must meet the requirements for MMU_LAZY_TLB_REFCOUNT=n (see above). 499config MMU_LAZY_TLB_SHOOTDOWN 500 bool 501 502config ARCH_HAVE_NMI_SAFE_CMPXCHG 503 bool 504 505config ARCH_HAS_NMI_SAFE_THIS_CPU_OPS 506 bool 507 508config HAVE_ALIGNED_STRUCT_PAGE 509 bool 510 help 511 This makes sure that struct pages are double word aligned and that 512 e.g. the SLUB allocator can perform double word atomic operations 513 on a struct page for better performance. However selecting this 514 might increase the size of a struct page by a word. 515 516config HAVE_CMPXCHG_LOCAL 517 bool 518 519config HAVE_CMPXCHG_DOUBLE 520 bool 521 522config ARCH_WEAK_RELEASE_ACQUIRE 523 bool 524 525config ARCH_WANT_IPC_PARSE_VERSION 526 bool 527 528config ARCH_WANT_COMPAT_IPC_PARSE_VERSION 529 bool 530 531config ARCH_WANT_OLD_COMPAT_IPC 532 select ARCH_WANT_COMPAT_IPC_PARSE_VERSION 533 bool 534 535config HAVE_ARCH_SECCOMP 536 bool 537 help 538 An arch should select this symbol to support seccomp mode 1 (the fixed 539 syscall policy), and must provide an overrides for __NR_seccomp_sigreturn, 540 and compat syscalls if the asm-generic/seccomp.h defaults need adjustment: 541 - __NR_seccomp_read_32 542 - __NR_seccomp_write_32 543 - __NR_seccomp_exit_32 544 - __NR_seccomp_sigreturn_32 545 546config HAVE_ARCH_SECCOMP_FILTER 547 bool 548 select HAVE_ARCH_SECCOMP 549 help 550 An arch should select this symbol if it provides all of these things: 551 - all the requirements for HAVE_ARCH_SECCOMP 552 - syscall_get_arch() 553 - syscall_get_arguments() 554 - syscall_rollback() 555 - syscall_set_return_value() 556 - SIGSYS siginfo_t support 557 - secure_computing is called from a ptrace_event()-safe context 558 - secure_computing return value is checked and a return value of -1 559 results in the system call being skipped immediately. 560 - seccomp syscall wired up 561 - if !HAVE_SPARSE_SYSCALL_NR, have SECCOMP_ARCH_NATIVE, 562 SECCOMP_ARCH_NATIVE_NR, SECCOMP_ARCH_NATIVE_NAME defined. If 563 COMPAT is supported, have the SECCOMP_ARCH_COMPAT* defines too. 564 565config SECCOMP 566 prompt "Enable seccomp to safely execute untrusted bytecode" 567 def_bool y 568 depends on HAVE_ARCH_SECCOMP 569 help 570 This kernel feature is useful for number crunching applications 571 that may need to handle untrusted bytecode during their 572 execution. By using pipes or other transports made available 573 to the process as file descriptors supporting the read/write 574 syscalls, it's possible to isolate those applications in their 575 own address space using seccomp. Once seccomp is enabled via 576 prctl(PR_SET_SECCOMP) or the seccomp() syscall, it cannot be 577 disabled and the task is only allowed to execute a few safe 578 syscalls defined by each seccomp mode. 579 580 If unsure, say Y. 581 582config SECCOMP_FILTER 583 def_bool y 584 depends on HAVE_ARCH_SECCOMP_FILTER && SECCOMP && NET 585 help 586 Enable tasks to build secure computing environments defined 587 in terms of Berkeley Packet Filter programs which implement 588 task-defined system call filtering polices. 589 590 See Documentation/userspace-api/seccomp_filter.rst for details. 591 592config SECCOMP_CACHE_DEBUG 593 bool "Show seccomp filter cache status in /proc/pid/seccomp_cache" 594 depends on SECCOMP_FILTER && !HAVE_SPARSE_SYSCALL_NR 595 depends on PROC_FS 596 help 597 This enables the /proc/pid/seccomp_cache interface to monitor 598 seccomp cache data. The file format is subject to change. Reading 599 the file requires CAP_SYS_ADMIN. 600 601 This option is for debugging only. Enabling presents the risk that 602 an adversary may be able to infer the seccomp filter logic. 603 604 If unsure, say N. 605 606config HAVE_ARCH_STACKLEAK 607 bool 608 help 609 An architecture should select this if it has the code which 610 fills the used part of the kernel stack with the STACKLEAK_POISON 611 value before returning from system calls. 612 613config HAVE_STACKPROTECTOR 614 bool 615 help 616 An arch should select this symbol if: 617 - it has implemented a stack canary (e.g. __stack_chk_guard) 618 619config STACKPROTECTOR 620 bool "Stack Protector buffer overflow detection" 621 depends on HAVE_STACKPROTECTOR 622 depends on $(cc-option,-fstack-protector) 623 default y 624 help 625 This option turns on the "stack-protector" GCC feature. This 626 feature puts, at the beginning of functions, a canary value on 627 the stack just before the return address, and validates 628 the value just before actually returning. Stack based buffer 629 overflows (that need to overwrite this return address) now also 630 overwrite the canary, which gets detected and the attack is then 631 neutralized via a kernel panic. 632 633 Functions will have the stack-protector canary logic added if they 634 have an 8-byte or larger character array on the stack. 635 636 This feature requires gcc version 4.2 or above, or a distribution 637 gcc with the feature backported ("-fstack-protector"). 638 639 On an x86 "defconfig" build, this feature adds canary checks to 640 about 3% of all kernel functions, which increases kernel code size 641 by about 0.3%. 642 643config STACKPROTECTOR_STRONG 644 bool "Strong Stack Protector" 645 depends on STACKPROTECTOR 646 depends on $(cc-option,-fstack-protector-strong) 647 default y 648 help 649 Functions will have the stack-protector canary logic added in any 650 of the following conditions: 651 652 - local variable's address used as part of the right hand side of an 653 assignment or function argument 654 - local variable is an array (or union containing an array), 655 regardless of array type or length 656 - uses register local variables 657 658 This feature requires gcc version 4.9 or above, or a distribution 659 gcc with the feature backported ("-fstack-protector-strong"). 660 661 On an x86 "defconfig" build, this feature adds canary checks to 662 about 20% of all kernel functions, which increases the kernel code 663 size by about 2%. 664 665config ARCH_SUPPORTS_SHADOW_CALL_STACK 666 bool 667 help 668 An architecture should select this if it supports the compiler's 669 Shadow Call Stack and implements runtime support for shadow stack 670 switching. 671 672config SHADOW_CALL_STACK 673 bool "Shadow Call Stack" 674 depends on ARCH_SUPPORTS_SHADOW_CALL_STACK 675 depends on DYNAMIC_FTRACE_WITH_ARGS || DYNAMIC_FTRACE_WITH_REGS || !FUNCTION_GRAPH_TRACER 676 help 677 This option enables the compiler's Shadow Call Stack, which 678 uses a shadow stack to protect function return addresses from 679 being overwritten by an attacker. More information can be found 680 in the compiler's documentation: 681 682 - Clang: https://clang.llvm.org/docs/ShadowCallStack.html 683 - GCC: https://gcc.gnu.org/onlinedocs/gcc/Instrumentation-Options.html#Instrumentation-Options 684 685 Note that security guarantees in the kernel differ from the 686 ones documented for user space. The kernel must store addresses 687 of shadow stacks in memory, which means an attacker capable of 688 reading and writing arbitrary memory may be able to locate them 689 and hijack control flow by modifying the stacks. 690 691config DYNAMIC_SCS 692 bool 693 help 694 Set by the arch code if it relies on code patching to insert the 695 shadow call stack push and pop instructions rather than on the 696 compiler. 697 698config LTO 699 bool 700 help 701 Selected if the kernel will be built using the compiler's LTO feature. 702 703config LTO_CLANG 704 bool 705 select LTO 706 help 707 Selected if the kernel will be built using Clang's LTO feature. 708 709config ARCH_SUPPORTS_LTO_CLANG 710 bool 711 help 712 An architecture should select this option if it supports: 713 - compiling with Clang, 714 - compiling inline assembly with Clang's integrated assembler, 715 - and linking with LLD. 716 717config ARCH_SUPPORTS_LTO_CLANG_THIN 718 bool 719 help 720 An architecture should select this option if it can support Clang's 721 ThinLTO mode. 722 723config HAS_LTO_CLANG 724 def_bool y 725 depends on CC_IS_CLANG && LD_IS_LLD && AS_IS_LLVM 726 depends on $(success,$(NM) --help | head -n 1 | grep -qi llvm) 727 depends on $(success,$(AR) --help | head -n 1 | grep -qi llvm) 728 depends on ARCH_SUPPORTS_LTO_CLANG 729 depends on !FTRACE_MCOUNT_USE_RECORDMCOUNT 730 # https://github.com/ClangBuiltLinux/linux/issues/1721 731 depends on (!KASAN || KASAN_HW_TAGS || CLANG_VERSION >= 170000) || !DEBUG_INFO 732 depends on (!KCOV || CLANG_VERSION >= 170000) || !DEBUG_INFO 733 depends on !GCOV_KERNEL 734 help 735 The compiler and Kconfig options support building with Clang's 736 LTO. 737 738choice 739 prompt "Link Time Optimization (LTO)" 740 default LTO_NONE 741 help 742 This option enables Link Time Optimization (LTO), which allows the 743 compiler to optimize binaries globally. 744 745 If unsure, select LTO_NONE. Note that LTO is very resource-intensive 746 so it's disabled by default. 747 748config LTO_NONE 749 bool "None" 750 help 751 Build the kernel normally, without Link Time Optimization (LTO). 752 753config LTO_CLANG_FULL 754 bool "Clang Full LTO (EXPERIMENTAL)" 755 depends on HAS_LTO_CLANG 756 depends on !COMPILE_TEST 757 select LTO_CLANG 758 help 759 This option enables Clang's full Link Time Optimization (LTO), which 760 allows the compiler to optimize the kernel globally. If you enable 761 this option, the compiler generates LLVM bitcode instead of ELF 762 object files, and the actual compilation from bitcode happens at 763 the LTO link step, which may take several minutes depending on the 764 kernel configuration. More information can be found from LLVM's 765 documentation: 766 767 https://llvm.org/docs/LinkTimeOptimization.html 768 769 During link time, this option can use a large amount of RAM, and 770 may take much longer than the ThinLTO option. 771 772config LTO_CLANG_THIN 773 bool "Clang ThinLTO (EXPERIMENTAL)" 774 depends on HAS_LTO_CLANG && ARCH_SUPPORTS_LTO_CLANG_THIN 775 select LTO_CLANG 776 help 777 This option enables Clang's ThinLTO, which allows for parallel 778 optimization and faster incremental compiles compared to the 779 CONFIG_LTO_CLANG_FULL option. More information can be found 780 from Clang's documentation: 781 782 https://clang.llvm.org/docs/ThinLTO.html 783 784 If unsure, say Y. 785endchoice 786 787config ARCH_SUPPORTS_CFI_CLANG 788 bool 789 help 790 An architecture should select this option if it can support Clang's 791 Control-Flow Integrity (CFI) checking. 792 793config ARCH_USES_CFI_TRAPS 794 bool 795 796config CFI_CLANG 797 bool "Use Clang's Control Flow Integrity (CFI)" 798 depends on ARCH_SUPPORTS_CFI_CLANG 799 depends on $(cc-option,-fsanitize=kcfi) 800 help 801 This option enables Clang’s forward-edge Control Flow Integrity 802 (CFI) checking, where the compiler injects a runtime check to each 803 indirect function call to ensure the target is a valid function with 804 the correct static type. This restricts possible call targets and 805 makes it more difficult for an attacker to exploit bugs that allow 806 the modification of stored function pointers. More information can be 807 found from Clang's documentation: 808 809 https://clang.llvm.org/docs/ControlFlowIntegrity.html 810 811config CFI_PERMISSIVE 812 bool "Use CFI in permissive mode" 813 depends on CFI_CLANG 814 help 815 When selected, Control Flow Integrity (CFI) violations result in a 816 warning instead of a kernel panic. This option should only be used 817 for finding indirect call type mismatches during development. 818 819 If unsure, say N. 820 821config HAVE_ARCH_WITHIN_STACK_FRAMES 822 bool 823 help 824 An architecture should select this if it can walk the kernel stack 825 frames to determine if an object is part of either the arguments 826 or local variables (i.e. that it excludes saved return addresses, 827 and similar) by implementing an inline arch_within_stack_frames(), 828 which is used by CONFIG_HARDENED_USERCOPY. 829 830config HAVE_CONTEXT_TRACKING_USER 831 bool 832 help 833 Provide kernel/user boundaries probes necessary for subsystems 834 that need it, such as userspace RCU extended quiescent state. 835 Syscalls need to be wrapped inside user_exit()-user_enter(), either 836 optimized behind static key or through the slow path using TIF_NOHZ 837 flag. Exceptions handlers must be wrapped as well. Irqs are already 838 protected inside ct_irq_enter/ct_irq_exit() but preemption or signal 839 handling on irq exit still need to be protected. 840 841config HAVE_CONTEXT_TRACKING_USER_OFFSTACK 842 bool 843 help 844 Architecture neither relies on exception_enter()/exception_exit() 845 nor on schedule_user(). Also preempt_schedule_notrace() and 846 preempt_schedule_irq() can't be called in a preemptible section 847 while context tracking is CONTEXT_USER. This feature reflects a sane 848 entry implementation where the following requirements are met on 849 critical entry code, ie: before user_exit() or after user_enter(): 850 851 - Critical entry code isn't preemptible (or better yet: 852 not interruptible). 853 - No use of RCU read side critical sections, unless ct_nmi_enter() 854 got called. 855 - No use of instrumentation, unless instrumentation_begin() got 856 called. 857 858config HAVE_TIF_NOHZ 859 bool 860 help 861 Arch relies on TIF_NOHZ and syscall slow path to implement context 862 tracking calls to user_enter()/user_exit(). 863 864config HAVE_VIRT_CPU_ACCOUNTING 865 bool 866 867config HAVE_VIRT_CPU_ACCOUNTING_IDLE 868 bool 869 help 870 Architecture has its own way to account idle CPU time and therefore 871 doesn't implement vtime_account_idle(). 872 873config ARCH_HAS_SCALED_CPUTIME 874 bool 875 876config HAVE_VIRT_CPU_ACCOUNTING_GEN 877 bool 878 default y if 64BIT 879 help 880 With VIRT_CPU_ACCOUNTING_GEN, cputime_t becomes 64-bit. 881 Before enabling this option, arch code must be audited 882 to ensure there are no races in concurrent read/write of 883 cputime_t. For example, reading/writing 64-bit cputime_t on 884 some 32-bit arches may require multiple accesses, so proper 885 locking is needed to protect against concurrent accesses. 886 887config HAVE_IRQ_TIME_ACCOUNTING 888 bool 889 help 890 Archs need to ensure they use a high enough resolution clock to 891 support irq time accounting and then call enable_sched_clock_irqtime(). 892 893config HAVE_MOVE_PUD 894 bool 895 help 896 Architectures that select this are able to move page tables at the 897 PUD level. If there are only 3 page table levels, the move effectively 898 happens at the PGD level. 899 900config HAVE_MOVE_PMD 901 bool 902 help 903 Archs that select this are able to move page tables at the PMD level. 904 905config HAVE_ARCH_TRANSPARENT_HUGEPAGE 906 bool 907 908config HAVE_ARCH_TRANSPARENT_HUGEPAGE_PUD 909 bool 910 911config HAVE_ARCH_HUGE_VMAP 912 bool 913 914# 915# Archs that select this would be capable of PMD-sized vmaps (i.e., 916# arch_vmap_pmd_supported() returns true). The VM_ALLOW_HUGE_VMAP flag 917# must be used to enable allocations to use hugepages. 918# 919config HAVE_ARCH_HUGE_VMALLOC 920 depends on HAVE_ARCH_HUGE_VMAP 921 bool 922 923config ARCH_WANT_HUGE_PMD_SHARE 924 bool 925 926# Archs that want to use pmd_mkwrite on kernel memory need it defined even 927# if there are no userspace memory management features that use it 928config ARCH_WANT_KERNEL_PMD_MKWRITE 929 bool 930 931config ARCH_WANT_PMD_MKWRITE 932 def_bool TRANSPARENT_HUGEPAGE || ARCH_WANT_KERNEL_PMD_MKWRITE 933 934config HAVE_ARCH_SOFT_DIRTY 935 bool 936 937config HAVE_MOD_ARCH_SPECIFIC 938 bool 939 help 940 The arch uses struct mod_arch_specific to store data. Many arches 941 just need a simple module loader without arch specific data - those 942 should not enable this. 943 944config MODULES_USE_ELF_RELA 945 bool 946 help 947 Modules only use ELF RELA relocations. Modules with ELF REL 948 relocations will give an error. 949 950config MODULES_USE_ELF_REL 951 bool 952 help 953 Modules only use ELF REL relocations. Modules with ELF RELA 954 relocations will give an error. 955 956config ARCH_WANTS_MODULES_DATA_IN_VMALLOC 957 bool 958 help 959 For architectures like powerpc/32 which have constraints on module 960 allocation and need to allocate module data outside of module area. 961 962config HAVE_IRQ_EXIT_ON_IRQ_STACK 963 bool 964 help 965 Architecture doesn't only execute the irq handler on the irq stack 966 but also irq_exit(). This way we can process softirqs on this irq 967 stack instead of switching to a new one when we call __do_softirq() 968 in the end of an hardirq. 969 This spares a stack switch and improves cache usage on softirq 970 processing. 971 972config HAVE_SOFTIRQ_ON_OWN_STACK 973 bool 974 help 975 Architecture provides a function to run __do_softirq() on a 976 separate stack. 977 978config SOFTIRQ_ON_OWN_STACK 979 def_bool HAVE_SOFTIRQ_ON_OWN_STACK && !PREEMPT_RT 980 981config ALTERNATE_USER_ADDRESS_SPACE 982 bool 983 help 984 Architectures set this when the CPU uses separate address 985 spaces for kernel and user space pointers. In this case, the 986 access_ok() check on a __user pointer is skipped. 987 988config PGTABLE_LEVELS 989 int 990 default 2 991 992config ARCH_HAS_ELF_RANDOMIZE 993 bool 994 help 995 An architecture supports choosing randomized locations for 996 stack, mmap, brk, and ET_DYN. Defined functions: 997 - arch_mmap_rnd() 998 - arch_randomize_brk() 999 1000config HAVE_ARCH_MMAP_RND_BITS 1001 bool 1002 help 1003 An arch should select this symbol if it supports setting a variable 1004 number of bits for use in establishing the base address for mmap 1005 allocations, has MMU enabled and provides values for both: 1006 - ARCH_MMAP_RND_BITS_MIN 1007 - ARCH_MMAP_RND_BITS_MAX 1008 1009config HAVE_EXIT_THREAD 1010 bool 1011 help 1012 An architecture implements exit_thread. 1013 1014config ARCH_MMAP_RND_BITS_MIN 1015 int 1016 1017config ARCH_MMAP_RND_BITS_MAX 1018 int 1019 1020config ARCH_MMAP_RND_BITS_DEFAULT 1021 int 1022 1023config ARCH_MMAP_RND_BITS 1024 int "Number of bits to use for ASLR of mmap base address" if EXPERT 1025 range ARCH_MMAP_RND_BITS_MIN ARCH_MMAP_RND_BITS_MAX 1026 default ARCH_MMAP_RND_BITS_DEFAULT if ARCH_MMAP_RND_BITS_DEFAULT 1027 default ARCH_MMAP_RND_BITS_MIN 1028 depends on HAVE_ARCH_MMAP_RND_BITS 1029 help 1030 This value can be used to select the number of bits to use to 1031 determine the random offset to the base address of vma regions 1032 resulting from mmap allocations. This value will be bounded 1033 by the architecture's minimum and maximum supported values. 1034 1035 This value can be changed after boot using the 1036 /proc/sys/vm/mmap_rnd_bits tunable 1037 1038config HAVE_ARCH_MMAP_RND_COMPAT_BITS 1039 bool 1040 help 1041 An arch should select this symbol if it supports running applications 1042 in compatibility mode, supports setting a variable number of bits for 1043 use in establishing the base address for mmap allocations, has MMU 1044 enabled and provides values for both: 1045 - ARCH_MMAP_RND_COMPAT_BITS_MIN 1046 - ARCH_MMAP_RND_COMPAT_BITS_MAX 1047 1048config ARCH_MMAP_RND_COMPAT_BITS_MIN 1049 int 1050 1051config ARCH_MMAP_RND_COMPAT_BITS_MAX 1052 int 1053 1054config ARCH_MMAP_RND_COMPAT_BITS_DEFAULT 1055 int 1056 1057config ARCH_MMAP_RND_COMPAT_BITS 1058 int "Number of bits to use for ASLR of mmap base address for compatible applications" if EXPERT 1059 range ARCH_MMAP_RND_COMPAT_BITS_MIN ARCH_MMAP_RND_COMPAT_BITS_MAX 1060 default ARCH_MMAP_RND_COMPAT_BITS_DEFAULT if ARCH_MMAP_RND_COMPAT_BITS_DEFAULT 1061 default ARCH_MMAP_RND_COMPAT_BITS_MIN 1062 depends on HAVE_ARCH_MMAP_RND_COMPAT_BITS 1063 help 1064 This value can be used to select the number of bits to use to 1065 determine the random offset to the base address of vma regions 1066 resulting from mmap allocations for compatible applications This 1067 value will be bounded by the architecture's minimum and maximum 1068 supported values. 1069 1070 This value can be changed after boot using the 1071 /proc/sys/vm/mmap_rnd_compat_bits tunable 1072 1073config HAVE_ARCH_COMPAT_MMAP_BASES 1074 bool 1075 help 1076 This allows 64bit applications to invoke 32-bit mmap() syscall 1077 and vice-versa 32-bit applications to call 64-bit mmap(). 1078 Required for applications doing different bitness syscalls. 1079 1080config PAGE_SIZE_LESS_THAN_64KB 1081 def_bool y 1082 depends on !ARM64_64K_PAGES 1083 depends on !PAGE_SIZE_64KB 1084 depends on !PARISC_PAGE_SIZE_64KB 1085 depends on PAGE_SIZE_LESS_THAN_256KB 1086 1087config PAGE_SIZE_LESS_THAN_256KB 1088 def_bool y 1089 depends on !PAGE_SIZE_256KB 1090 1091# This allows to use a set of generic functions to determine mmap base 1092# address by giving priority to top-down scheme only if the process 1093# is not in legacy mode (compat task, unlimited stack size or 1094# sysctl_legacy_va_layout). 1095# Architecture that selects this option can provide its own version of: 1096# - STACK_RND_MASK 1097config ARCH_WANT_DEFAULT_TOPDOWN_MMAP_LAYOUT 1098 bool 1099 depends on MMU 1100 select ARCH_HAS_ELF_RANDOMIZE 1101 1102config HAVE_OBJTOOL 1103 bool 1104 1105config HAVE_JUMP_LABEL_HACK 1106 bool 1107 1108config HAVE_NOINSTR_HACK 1109 bool 1110 1111config HAVE_NOINSTR_VALIDATION 1112 bool 1113 1114config HAVE_UACCESS_VALIDATION 1115 bool 1116 select OBJTOOL 1117 1118config HAVE_STACK_VALIDATION 1119 bool 1120 help 1121 Architecture supports objtool compile-time frame pointer rule 1122 validation. 1123 1124config HAVE_RELIABLE_STACKTRACE 1125 bool 1126 help 1127 Architecture has either save_stack_trace_tsk_reliable() or 1128 arch_stack_walk_reliable() function which only returns a stack trace 1129 if it can guarantee the trace is reliable. 1130 1131config HAVE_ARCH_HASH 1132 bool 1133 default n 1134 help 1135 If this is set, the architecture provides an <asm/hash.h> 1136 file which provides platform-specific implementations of some 1137 functions in <linux/hash.h> or fs/namei.c. 1138 1139config HAVE_ARCH_NVRAM_OPS 1140 bool 1141 1142config ISA_BUS_API 1143 def_bool ISA 1144 1145# 1146# ABI hall of shame 1147# 1148config CLONE_BACKWARDS 1149 bool 1150 help 1151 Architecture has tls passed as the 4th argument of clone(2), 1152 not the 5th one. 1153 1154config CLONE_BACKWARDS2 1155 bool 1156 help 1157 Architecture has the first two arguments of clone(2) swapped. 1158 1159config CLONE_BACKWARDS3 1160 bool 1161 help 1162 Architecture has tls passed as the 3rd argument of clone(2), 1163 not the 5th one. 1164 1165config ODD_RT_SIGACTION 1166 bool 1167 help 1168 Architecture has unusual rt_sigaction(2) arguments 1169 1170config OLD_SIGSUSPEND 1171 bool 1172 help 1173 Architecture has old sigsuspend(2) syscall, of one-argument variety 1174 1175config OLD_SIGSUSPEND3 1176 bool 1177 help 1178 Even weirder antique ABI - three-argument sigsuspend(2) 1179 1180config OLD_SIGACTION 1181 bool 1182 help 1183 Architecture has old sigaction(2) syscall. Nope, not the same 1184 as OLD_SIGSUSPEND | OLD_SIGSUSPEND3 - alpha has sigsuspend(2), 1185 but fairly different variant of sigaction(2), thanks to OSF/1 1186 compatibility... 1187 1188config COMPAT_OLD_SIGACTION 1189 bool 1190 1191config COMPAT_32BIT_TIME 1192 bool "Provide system calls for 32-bit time_t" 1193 default !64BIT || COMPAT 1194 help 1195 This enables 32 bit time_t support in addition to 64 bit time_t support. 1196 This is relevant on all 32-bit architectures, and 64-bit architectures 1197 as part of compat syscall handling. 1198 1199config ARCH_NO_PREEMPT 1200 bool 1201 1202config ARCH_SUPPORTS_RT 1203 bool 1204 1205config CPU_NO_EFFICIENT_FFS 1206 def_bool n 1207 1208config HAVE_ARCH_VMAP_STACK 1209 def_bool n 1210 help 1211 An arch should select this symbol if it can support kernel stacks 1212 in vmalloc space. This means: 1213 1214 - vmalloc space must be large enough to hold many kernel stacks. 1215 This may rule out many 32-bit architectures. 1216 1217 - Stacks in vmalloc space need to work reliably. For example, if 1218 vmap page tables are created on demand, either this mechanism 1219 needs to work while the stack points to a virtual address with 1220 unpopulated page tables or arch code (switch_to() and switch_mm(), 1221 most likely) needs to ensure that the stack's page table entries 1222 are populated before running on a possibly unpopulated stack. 1223 1224 - If the stack overflows into a guard page, something reasonable 1225 should happen. The definition of "reasonable" is flexible, but 1226 instantly rebooting without logging anything would be unfriendly. 1227 1228config VMAP_STACK 1229 default y 1230 bool "Use a virtually-mapped stack" 1231 depends on HAVE_ARCH_VMAP_STACK 1232 depends on !KASAN || KASAN_HW_TAGS || KASAN_VMALLOC 1233 help 1234 Enable this if you want the use virtually-mapped kernel stacks 1235 with guard pages. This causes kernel stack overflows to be 1236 caught immediately rather than causing difficult-to-diagnose 1237 corruption. 1238 1239 To use this with software KASAN modes, the architecture must support 1240 backing virtual mappings with real shadow memory, and KASAN_VMALLOC 1241 must be enabled. 1242 1243config HAVE_ARCH_RANDOMIZE_KSTACK_OFFSET 1244 def_bool n 1245 help 1246 An arch should select this symbol if it can support kernel stack 1247 offset randomization with calls to add_random_kstack_offset() 1248 during syscall entry and choose_random_kstack_offset() during 1249 syscall exit. Careful removal of -fstack-protector-strong and 1250 -fstack-protector should also be applied to the entry code and 1251 closely examined, as the artificial stack bump looks like an array 1252 to the compiler, so it will attempt to add canary checks regardless 1253 of the static branch state. 1254 1255config RANDOMIZE_KSTACK_OFFSET 1256 bool "Support for randomizing kernel stack offset on syscall entry" if EXPERT 1257 default y 1258 depends on HAVE_ARCH_RANDOMIZE_KSTACK_OFFSET 1259 depends on INIT_STACK_NONE || !CC_IS_CLANG || CLANG_VERSION >= 140000 1260 help 1261 The kernel stack offset can be randomized (after pt_regs) by 1262 roughly 5 bits of entropy, frustrating memory corruption 1263 attacks that depend on stack address determinism or 1264 cross-syscall address exposures. 1265 1266 The feature is controlled via the "randomize_kstack_offset=on/off" 1267 kernel boot param, and if turned off has zero overhead due to its use 1268 of static branches (see JUMP_LABEL). 1269 1270 If unsure, say Y. 1271 1272config RANDOMIZE_KSTACK_OFFSET_DEFAULT 1273 bool "Default state of kernel stack offset randomization" 1274 depends on RANDOMIZE_KSTACK_OFFSET 1275 help 1276 Kernel stack offset randomization is controlled by kernel boot param 1277 "randomize_kstack_offset=on/off", and this config chooses the default 1278 boot state. 1279 1280config ARCH_OPTIONAL_KERNEL_RWX 1281 def_bool n 1282 1283config ARCH_OPTIONAL_KERNEL_RWX_DEFAULT 1284 def_bool n 1285 1286config ARCH_HAS_STRICT_KERNEL_RWX 1287 def_bool n 1288 1289config STRICT_KERNEL_RWX 1290 bool "Make kernel text and rodata read-only" if ARCH_OPTIONAL_KERNEL_RWX 1291 depends on ARCH_HAS_STRICT_KERNEL_RWX 1292 default !ARCH_OPTIONAL_KERNEL_RWX || ARCH_OPTIONAL_KERNEL_RWX_DEFAULT 1293 help 1294 If this is set, kernel text and rodata memory will be made read-only, 1295 and non-text memory will be made non-executable. This provides 1296 protection against certain security exploits (e.g. executing the heap 1297 or modifying text) 1298 1299 These features are considered standard security practice these days. 1300 You should say Y here in almost all cases. 1301 1302config ARCH_HAS_STRICT_MODULE_RWX 1303 def_bool n 1304 1305config STRICT_MODULE_RWX 1306 bool "Set loadable kernel module data as NX and text as RO" if ARCH_OPTIONAL_KERNEL_RWX 1307 depends on ARCH_HAS_STRICT_MODULE_RWX && MODULES 1308 default !ARCH_OPTIONAL_KERNEL_RWX || ARCH_OPTIONAL_KERNEL_RWX_DEFAULT 1309 help 1310 If this is set, module text and rodata memory will be made read-only, 1311 and non-text memory will be made non-executable. This provides 1312 protection against certain security exploits (e.g. writing to text) 1313 1314# select if the architecture provides an asm/dma-direct.h header 1315config ARCH_HAS_PHYS_TO_DMA 1316 bool 1317 1318config HAVE_ARCH_COMPILER_H 1319 bool 1320 help 1321 An architecture can select this if it provides an 1322 asm/compiler.h header that should be included after 1323 linux/compiler-*.h in order to override macro definitions that those 1324 headers generally provide. 1325 1326config HAVE_ARCH_PREL32_RELOCATIONS 1327 bool 1328 help 1329 May be selected by an architecture if it supports place-relative 1330 32-bit relocations, both in the toolchain and in the module loader, 1331 in which case relative references can be used in special sections 1332 for PCI fixup, initcalls etc which are only half the size on 64 bit 1333 architectures, and don't require runtime relocation on relocatable 1334 kernels. 1335 1336config ARCH_USE_MEMREMAP_PROT 1337 bool 1338 1339config LOCK_EVENT_COUNTS 1340 bool "Locking event counts collection" 1341 depends on DEBUG_FS 1342 help 1343 Enable light-weight counting of various locking related events 1344 in the system with minimal performance impact. This reduces 1345 the chance of application behavior change because of timing 1346 differences. The counts are reported via debugfs. 1347 1348# Select if the architecture has support for applying RELR relocations. 1349config ARCH_HAS_RELR 1350 bool 1351 1352config RELR 1353 bool "Use RELR relocation packing" 1354 depends on ARCH_HAS_RELR && TOOLS_SUPPORT_RELR 1355 default y 1356 help 1357 Store the kernel's dynamic relocations in the RELR relocation packing 1358 format. Requires a compatible linker (LLD supports this feature), as 1359 well as compatible NM and OBJCOPY utilities (llvm-nm and llvm-objcopy 1360 are compatible). 1361 1362config ARCH_HAS_MEM_ENCRYPT 1363 bool 1364 1365config ARCH_HAS_CC_PLATFORM 1366 bool 1367 1368config HAVE_SPARSE_SYSCALL_NR 1369 bool 1370 help 1371 An architecture should select this if its syscall numbering is sparse 1372 to save space. For example, MIPS architecture has a syscall array with 1373 entries at 4000, 5000 and 6000 locations. This option turns on syscall 1374 related optimizations for a given architecture. 1375 1376config ARCH_HAS_VDSO_DATA 1377 bool 1378 1379config HAVE_STATIC_CALL 1380 bool 1381 1382config HAVE_STATIC_CALL_INLINE 1383 bool 1384 depends on HAVE_STATIC_CALL 1385 select OBJTOOL 1386 1387config HAVE_PREEMPT_DYNAMIC 1388 bool 1389 1390config HAVE_PREEMPT_DYNAMIC_CALL 1391 bool 1392 depends on HAVE_STATIC_CALL 1393 select HAVE_PREEMPT_DYNAMIC 1394 help 1395 An architecture should select this if it can handle the preemption 1396 model being selected at boot time using static calls. 1397 1398 Where an architecture selects HAVE_STATIC_CALL_INLINE, any call to a 1399 preemption function will be patched directly. 1400 1401 Where an architecture does not select HAVE_STATIC_CALL_INLINE, any 1402 call to a preemption function will go through a trampoline, and the 1403 trampoline will be patched. 1404 1405 It is strongly advised to support inline static call to avoid any 1406 overhead. 1407 1408config HAVE_PREEMPT_DYNAMIC_KEY 1409 bool 1410 depends on HAVE_ARCH_JUMP_LABEL 1411 select HAVE_PREEMPT_DYNAMIC 1412 help 1413 An architecture should select this if it can handle the preemption 1414 model being selected at boot time using static keys. 1415 1416 Each preemption function will be given an early return based on a 1417 static key. This should have slightly lower overhead than non-inline 1418 static calls, as this effectively inlines each trampoline into the 1419 start of its callee. This may avoid redundant work, and may 1420 integrate better with CFI schemes. 1421 1422 This will have greater overhead than using inline static calls as 1423 the call to the preemption function cannot be entirely elided. 1424 1425config ARCH_WANT_LD_ORPHAN_WARN 1426 bool 1427 help 1428 An arch should select this symbol once all linker sections are explicitly 1429 included, size-asserted, or discarded in the linker scripts. This is 1430 important because we never want expected sections to be placed heuristically 1431 by the linker, since the locations of such sections can change between linker 1432 versions. 1433 1434config HAVE_ARCH_PFN_VALID 1435 bool 1436 1437config ARCH_SUPPORTS_DEBUG_PAGEALLOC 1438 bool 1439 1440config ARCH_SUPPORTS_PAGE_TABLE_CHECK 1441 bool 1442 1443config ARCH_SPLIT_ARG64 1444 bool 1445 help 1446 If a 32-bit architecture requires 64-bit arguments to be split into 1447 pairs of 32-bit arguments, select this option. 1448 1449config ARCH_HAS_ELFCORE_COMPAT 1450 bool 1451 1452config ARCH_HAS_PARANOID_L1D_FLUSH 1453 bool 1454 1455config ARCH_HAVE_TRACE_MMIO_ACCESS 1456 bool 1457 1458config DYNAMIC_SIGFRAME 1459 bool 1460 1461# Select, if arch has a named attribute group bound to NUMA device nodes. 1462config HAVE_ARCH_NODE_DEV_GROUP 1463 bool 1464 1465config ARCH_HAS_HW_PTE_YOUNG 1466 bool 1467 help 1468 Architectures that select this option are capable of setting the 1469 accessed bit in PTE entries when using them as part of linear address 1470 translations. Architectures that require runtime check should select 1471 this option and override arch_has_hw_pte_young(). 1472 1473config ARCH_HAS_NONLEAF_PMD_YOUNG 1474 bool 1475 help 1476 Architectures that select this option are capable of setting the 1477 accessed bit in non-leaf PMD entries when using them as part of linear 1478 address translations. Page table walkers that clear the accessed bit 1479 may use this capability to reduce their search space. 1480 1481source "kernel/gcov/Kconfig" 1482 1483source "scripts/gcc-plugins/Kconfig" 1484 1485config FUNCTION_ALIGNMENT_4B 1486 bool 1487 1488config FUNCTION_ALIGNMENT_8B 1489 bool 1490 1491config FUNCTION_ALIGNMENT_16B 1492 bool 1493 1494config FUNCTION_ALIGNMENT_32B 1495 bool 1496 1497config FUNCTION_ALIGNMENT_64B 1498 bool 1499 1500config FUNCTION_ALIGNMENT 1501 int 1502 default 64 if FUNCTION_ALIGNMENT_64B 1503 default 32 if FUNCTION_ALIGNMENT_32B 1504 default 16 if FUNCTION_ALIGNMENT_16B 1505 default 8 if FUNCTION_ALIGNMENT_8B 1506 default 4 if FUNCTION_ALIGNMENT_4B 1507 default 0 1508 1509endmenu 1510