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# Select if arch init_task must go in the __init_task_data section 305config ARCH_TASK_STRUCT_ON_STACK 306 bool 307 308# Select if arch has its private alloc_task_struct() function 309config ARCH_TASK_STRUCT_ALLOCATOR 310 bool 311 312config HAVE_ARCH_THREAD_STRUCT_WHITELIST 313 bool 314 depends on !ARCH_TASK_STRUCT_ALLOCATOR 315 help 316 An architecture should select this to provide hardened usercopy 317 knowledge about what region of the thread_struct should be 318 whitelisted for copying to userspace. Normally this is only the 319 FPU registers. Specifically, arch_thread_struct_whitelist() 320 should be implemented. Without this, the entire thread_struct 321 field in task_struct will be left whitelisted. 322 323# Select if arch has its private alloc_thread_stack() function 324config ARCH_THREAD_STACK_ALLOCATOR 325 bool 326 327# Select if arch wants to size task_struct dynamically via arch_task_struct_size: 328config ARCH_WANTS_DYNAMIC_TASK_STRUCT 329 bool 330 331config ARCH_WANTS_NO_INSTR 332 bool 333 help 334 An architecture should select this if the noinstr macro is being used on 335 functions to denote that the toolchain should avoid instrumenting such 336 functions and is required for correctness. 337 338config ARCH_32BIT_OFF_T 339 bool 340 depends on !64BIT 341 help 342 All new 32-bit architectures should have 64-bit off_t type on 343 userspace side which corresponds to the loff_t kernel type. This 344 is the requirement for modern ABIs. Some existing architectures 345 still support 32-bit off_t. This option is enabled for all such 346 architectures explicitly. 347 348# Selected by 64 bit architectures which have a 32 bit f_tinode in struct ustat 349config ARCH_32BIT_USTAT_F_TINODE 350 bool 351 352config HAVE_ASM_MODVERSIONS 353 bool 354 help 355 This symbol should be selected by an architecture if it provides 356 <asm/asm-prototypes.h> to support the module versioning for symbols 357 exported from assembly code. 358 359config HAVE_REGS_AND_STACK_ACCESS_API 360 bool 361 help 362 This symbol should be selected by an architecture if it supports 363 the API needed to access registers and stack entries from pt_regs, 364 declared in asm/ptrace.h 365 For example the kprobes-based event tracer needs this API. 366 367config HAVE_RSEQ 368 bool 369 depends on HAVE_REGS_AND_STACK_ACCESS_API 370 help 371 This symbol should be selected by an architecture if it 372 supports an implementation of restartable sequences. 373 374config HAVE_RUST 375 bool 376 help 377 This symbol should be selected by an architecture if it 378 supports Rust. 379 380config HAVE_FUNCTION_ARG_ACCESS_API 381 bool 382 help 383 This symbol should be selected by an architecture if it supports 384 the API needed to access function arguments from pt_regs, 385 declared in asm/ptrace.h 386 387config HAVE_HW_BREAKPOINT 388 bool 389 depends on PERF_EVENTS 390 391config HAVE_MIXED_BREAKPOINTS_REGS 392 bool 393 depends on HAVE_HW_BREAKPOINT 394 help 395 Depending on the arch implementation of hardware breakpoints, 396 some of them have separate registers for data and instruction 397 breakpoints addresses, others have mixed registers to store 398 them but define the access type in a control register. 399 Select this option if your arch implements breakpoints under the 400 latter fashion. 401 402config HAVE_USER_RETURN_NOTIFIER 403 bool 404 405config HAVE_PERF_EVENTS_NMI 406 bool 407 help 408 System hardware can generate an NMI using the perf event 409 subsystem. Also has support for calculating CPU cycle events 410 to determine how many clock cycles in a given period. 411 412config HAVE_HARDLOCKUP_DETECTOR_PERF 413 bool 414 depends on HAVE_PERF_EVENTS_NMI 415 help 416 The arch chooses to use the generic perf-NMI-based hardlockup 417 detector. Must define HAVE_PERF_EVENTS_NMI. 418 419config HAVE_HARDLOCKUP_DETECTOR_ARCH 420 bool 421 help 422 The arch provides its own hardlockup detector implementation instead 423 of the generic ones. 424 425 It uses the same command line parameters, and sysctl interface, 426 as the generic hardlockup detectors. 427 428config HAVE_PERF_REGS 429 bool 430 help 431 Support selective register dumps for perf events. This includes 432 bit-mapping of each registers and a unique architecture id. 433 434config HAVE_PERF_USER_STACK_DUMP 435 bool 436 help 437 Support user stack dumps for perf event samples. This needs 438 access to the user stack pointer which is not unified across 439 architectures. 440 441config HAVE_ARCH_JUMP_LABEL 442 bool 443 444config HAVE_ARCH_JUMP_LABEL_RELATIVE 445 bool 446 447config MMU_GATHER_TABLE_FREE 448 bool 449 450config MMU_GATHER_RCU_TABLE_FREE 451 bool 452 select MMU_GATHER_TABLE_FREE 453 454config MMU_GATHER_PAGE_SIZE 455 bool 456 457config MMU_GATHER_NO_RANGE 458 bool 459 select MMU_GATHER_MERGE_VMAS 460 461config MMU_GATHER_NO_FLUSH_CACHE 462 bool 463 464config MMU_GATHER_MERGE_VMAS 465 bool 466 467config MMU_GATHER_NO_GATHER 468 bool 469 depends on MMU_GATHER_TABLE_FREE 470 471config ARCH_WANT_IRQS_OFF_ACTIVATE_MM 472 bool 473 help 474 Temporary select until all architectures can be converted to have 475 irqs disabled over activate_mm. Architectures that do IPI based TLB 476 shootdowns should enable this. 477 478# Use normal mm refcounting for MMU_LAZY_TLB kernel thread references. 479# MMU_LAZY_TLB_REFCOUNT=n can improve the scalability of context switching 480# to/from kernel threads when the same mm is running on a lot of CPUs (a large 481# multi-threaded application), by reducing contention on the mm refcount. 482# 483# This can be disabled if the architecture ensures no CPUs are using an mm as a 484# "lazy tlb" beyond its final refcount (i.e., by the time __mmdrop frees the mm 485# or its kernel page tables). This could be arranged by arch_exit_mmap(), or 486# final exit(2) TLB flush, for example. 487# 488# To implement this, an arch *must*: 489# Ensure the _lazy_tlb variants of mmgrab/mmdrop are used when manipulating 490# the lazy tlb reference of a kthread's ->active_mm (non-arch code has been 491# converted already). 492config MMU_LAZY_TLB_REFCOUNT 493 def_bool y 494 depends on !MMU_LAZY_TLB_SHOOTDOWN 495 496# This option allows MMU_LAZY_TLB_REFCOUNT=n. It ensures no CPUs are using an 497# mm as a lazy tlb beyond its last reference count, by shooting down these 498# users before the mm is deallocated. __mmdrop() first IPIs all CPUs that may 499# be using the mm as a lazy tlb, so that they may switch themselves to using 500# init_mm for their active mm. mm_cpumask(mm) is used to determine which CPUs 501# may be using mm as a lazy tlb mm. 502# 503# To implement this, an arch *must*: 504# - At the time of the final mmdrop of the mm, ensure mm_cpumask(mm) contains 505# at least all possible CPUs in which the mm is lazy. 506# - It must meet the requirements for MMU_LAZY_TLB_REFCOUNT=n (see above). 507config MMU_LAZY_TLB_SHOOTDOWN 508 bool 509 510config ARCH_HAVE_NMI_SAFE_CMPXCHG 511 bool 512 513config ARCH_HAS_NMI_SAFE_THIS_CPU_OPS 514 bool 515 516config HAVE_ALIGNED_STRUCT_PAGE 517 bool 518 help 519 This makes sure that struct pages are double word aligned and that 520 e.g. the SLUB allocator can perform double word atomic operations 521 on a struct page for better performance. However selecting this 522 might increase the size of a struct page by a word. 523 524config HAVE_CMPXCHG_LOCAL 525 bool 526 527config HAVE_CMPXCHG_DOUBLE 528 bool 529 530config ARCH_WEAK_RELEASE_ACQUIRE 531 bool 532 533config ARCH_WANT_IPC_PARSE_VERSION 534 bool 535 536config ARCH_WANT_COMPAT_IPC_PARSE_VERSION 537 bool 538 539config ARCH_WANT_OLD_COMPAT_IPC 540 select ARCH_WANT_COMPAT_IPC_PARSE_VERSION 541 bool 542 543config HAVE_ARCH_SECCOMP 544 bool 545 help 546 An arch should select this symbol to support seccomp mode 1 (the fixed 547 syscall policy), and must provide an overrides for __NR_seccomp_sigreturn, 548 and compat syscalls if the asm-generic/seccomp.h defaults need adjustment: 549 - __NR_seccomp_read_32 550 - __NR_seccomp_write_32 551 - __NR_seccomp_exit_32 552 - __NR_seccomp_sigreturn_32 553 554config HAVE_ARCH_SECCOMP_FILTER 555 bool 556 select HAVE_ARCH_SECCOMP 557 help 558 An arch should select this symbol if it provides all of these things: 559 - all the requirements for HAVE_ARCH_SECCOMP 560 - syscall_get_arch() 561 - syscall_get_arguments() 562 - syscall_rollback() 563 - syscall_set_return_value() 564 - SIGSYS siginfo_t support 565 - secure_computing is called from a ptrace_event()-safe context 566 - secure_computing return value is checked and a return value of -1 567 results in the system call being skipped immediately. 568 - seccomp syscall wired up 569 - if !HAVE_SPARSE_SYSCALL_NR, have SECCOMP_ARCH_NATIVE, 570 SECCOMP_ARCH_NATIVE_NR, SECCOMP_ARCH_NATIVE_NAME defined. If 571 COMPAT is supported, have the SECCOMP_ARCH_COMPAT* defines too. 572 573config SECCOMP 574 prompt "Enable seccomp to safely execute untrusted bytecode" 575 def_bool y 576 depends on HAVE_ARCH_SECCOMP 577 help 578 This kernel feature is useful for number crunching applications 579 that may need to handle untrusted bytecode during their 580 execution. By using pipes or other transports made available 581 to the process as file descriptors supporting the read/write 582 syscalls, it's possible to isolate those applications in their 583 own address space using seccomp. Once seccomp is enabled via 584 prctl(PR_SET_SECCOMP) or the seccomp() syscall, it cannot be 585 disabled and the task is only allowed to execute a few safe 586 syscalls defined by each seccomp mode. 587 588 If unsure, say Y. 589 590config SECCOMP_FILTER 591 def_bool y 592 depends on HAVE_ARCH_SECCOMP_FILTER && SECCOMP && NET 593 help 594 Enable tasks to build secure computing environments defined 595 in terms of Berkeley Packet Filter programs which implement 596 task-defined system call filtering polices. 597 598 See Documentation/userspace-api/seccomp_filter.rst for details. 599 600config SECCOMP_CACHE_DEBUG 601 bool "Show seccomp filter cache status in /proc/pid/seccomp_cache" 602 depends on SECCOMP_FILTER && !HAVE_SPARSE_SYSCALL_NR 603 depends on PROC_FS 604 help 605 This enables the /proc/pid/seccomp_cache interface to monitor 606 seccomp cache data. The file format is subject to change. Reading 607 the file requires CAP_SYS_ADMIN. 608 609 This option is for debugging only. Enabling presents the risk that 610 an adversary may be able to infer the seccomp filter logic. 611 612 If unsure, say N. 613 614config HAVE_ARCH_STACKLEAK 615 bool 616 help 617 An architecture should select this if it has the code which 618 fills the used part of the kernel stack with the STACKLEAK_POISON 619 value before returning from system calls. 620 621config HAVE_STACKPROTECTOR 622 bool 623 help 624 An arch should select this symbol if: 625 - it has implemented a stack canary (e.g. __stack_chk_guard) 626 627config STACKPROTECTOR 628 bool "Stack Protector buffer overflow detection" 629 depends on HAVE_STACKPROTECTOR 630 depends on $(cc-option,-fstack-protector) 631 default y 632 help 633 This option turns on the "stack-protector" GCC feature. This 634 feature puts, at the beginning of functions, a canary value on 635 the stack just before the return address, and validates 636 the value just before actually returning. Stack based buffer 637 overflows (that need to overwrite this return address) now also 638 overwrite the canary, which gets detected and the attack is then 639 neutralized via a kernel panic. 640 641 Functions will have the stack-protector canary logic added if they 642 have an 8-byte or larger character array on the stack. 643 644 This feature requires gcc version 4.2 or above, or a distribution 645 gcc with the feature backported ("-fstack-protector"). 646 647 On an x86 "defconfig" build, this feature adds canary checks to 648 about 3% of all kernel functions, which increases kernel code size 649 by about 0.3%. 650 651config STACKPROTECTOR_STRONG 652 bool "Strong Stack Protector" 653 depends on STACKPROTECTOR 654 depends on $(cc-option,-fstack-protector-strong) 655 default y 656 help 657 Functions will have the stack-protector canary logic added in any 658 of the following conditions: 659 660 - local variable's address used as part of the right hand side of an 661 assignment or function argument 662 - local variable is an array (or union containing an array), 663 regardless of array type or length 664 - uses register local variables 665 666 This feature requires gcc version 4.9 or above, or a distribution 667 gcc with the feature backported ("-fstack-protector-strong"). 668 669 On an x86 "defconfig" build, this feature adds canary checks to 670 about 20% of all kernel functions, which increases the kernel code 671 size by about 2%. 672 673config ARCH_SUPPORTS_SHADOW_CALL_STACK 674 bool 675 help 676 An architecture should select this if it supports the compiler's 677 Shadow Call Stack and implements runtime support for shadow stack 678 switching. 679 680config SHADOW_CALL_STACK 681 bool "Shadow Call Stack" 682 depends on ARCH_SUPPORTS_SHADOW_CALL_STACK 683 depends on DYNAMIC_FTRACE_WITH_ARGS || DYNAMIC_FTRACE_WITH_REGS || !FUNCTION_GRAPH_TRACER 684 depends on MMU 685 help 686 This option enables the compiler's Shadow Call Stack, which 687 uses a shadow stack to protect function return addresses from 688 being overwritten by an attacker. More information can be found 689 in the compiler's documentation: 690 691 - Clang: https://clang.llvm.org/docs/ShadowCallStack.html 692 - GCC: https://gcc.gnu.org/onlinedocs/gcc/Instrumentation-Options.html#Instrumentation-Options 693 694 Note that security guarantees in the kernel differ from the 695 ones documented for user space. The kernel must store addresses 696 of shadow stacks in memory, which means an attacker capable of 697 reading and writing arbitrary memory may be able to locate them 698 and hijack control flow by modifying the stacks. 699 700config DYNAMIC_SCS 701 bool 702 help 703 Set by the arch code if it relies on code patching to insert the 704 shadow call stack push and pop instructions rather than on the 705 compiler. 706 707config LTO 708 bool 709 help 710 Selected if the kernel will be built using the compiler's LTO feature. 711 712config LTO_CLANG 713 bool 714 select LTO 715 help 716 Selected if the kernel will be built using Clang's LTO feature. 717 718config ARCH_SUPPORTS_LTO_CLANG 719 bool 720 help 721 An architecture should select this option if it supports: 722 - compiling with Clang, 723 - compiling inline assembly with Clang's integrated assembler, 724 - and linking with LLD. 725 726config ARCH_SUPPORTS_LTO_CLANG_THIN 727 bool 728 help 729 An architecture should select this option if it can support Clang's 730 ThinLTO mode. 731 732config HAS_LTO_CLANG 733 def_bool y 734 depends on CC_IS_CLANG && LD_IS_LLD && AS_IS_LLVM 735 depends on $(success,$(NM) --help | head -n 1 | grep -qi llvm) 736 depends on $(success,$(AR) --help | head -n 1 | grep -qi llvm) 737 depends on ARCH_SUPPORTS_LTO_CLANG 738 depends on !FTRACE_MCOUNT_USE_RECORDMCOUNT 739 # https://github.com/ClangBuiltLinux/linux/issues/1721 740 depends on (!KASAN || KASAN_HW_TAGS || CLANG_VERSION >= 170000) || !DEBUG_INFO 741 depends on (!KCOV || CLANG_VERSION >= 170000) || !DEBUG_INFO 742 depends on !GCOV_KERNEL 743 help 744 The compiler and Kconfig options support building with Clang's 745 LTO. 746 747choice 748 prompt "Link Time Optimization (LTO)" 749 default LTO_NONE 750 help 751 This option enables Link Time Optimization (LTO), which allows the 752 compiler to optimize binaries globally. 753 754 If unsure, select LTO_NONE. Note that LTO is very resource-intensive 755 so it's disabled by default. 756 757config LTO_NONE 758 bool "None" 759 help 760 Build the kernel normally, without Link Time Optimization (LTO). 761 762config LTO_CLANG_FULL 763 bool "Clang Full LTO (EXPERIMENTAL)" 764 depends on HAS_LTO_CLANG 765 depends on !COMPILE_TEST 766 select LTO_CLANG 767 help 768 This option enables Clang's full Link Time Optimization (LTO), which 769 allows the compiler to optimize the kernel globally. If you enable 770 this option, the compiler generates LLVM bitcode instead of ELF 771 object files, and the actual compilation from bitcode happens at 772 the LTO link step, which may take several minutes depending on the 773 kernel configuration. More information can be found from LLVM's 774 documentation: 775 776 https://llvm.org/docs/LinkTimeOptimization.html 777 778 During link time, this option can use a large amount of RAM, and 779 may take much longer than the ThinLTO option. 780 781config LTO_CLANG_THIN 782 bool "Clang ThinLTO (EXPERIMENTAL)" 783 depends on HAS_LTO_CLANG && ARCH_SUPPORTS_LTO_CLANG_THIN 784 select LTO_CLANG 785 help 786 This option enables Clang's ThinLTO, which allows for parallel 787 optimization and faster incremental compiles compared to the 788 CONFIG_LTO_CLANG_FULL option. More information can be found 789 from Clang's documentation: 790 791 https://clang.llvm.org/docs/ThinLTO.html 792 793 If unsure, say Y. 794endchoice 795 796config ARCH_SUPPORTS_CFI_CLANG 797 bool 798 help 799 An architecture should select this option if it can support Clang's 800 Control-Flow Integrity (CFI) checking. 801 802config ARCH_USES_CFI_TRAPS 803 bool 804 805config CFI_CLANG 806 bool "Use Clang's Control Flow Integrity (CFI)" 807 depends on ARCH_SUPPORTS_CFI_CLANG 808 depends on $(cc-option,-fsanitize=kcfi) 809 help 810 This option enables Clang’s forward-edge Control Flow Integrity 811 (CFI) checking, where the compiler injects a runtime check to each 812 indirect function call to ensure the target is a valid function with 813 the correct static type. This restricts possible call targets and 814 makes it more difficult for an attacker to exploit bugs that allow 815 the modification of stored function pointers. More information can be 816 found from Clang's documentation: 817 818 https://clang.llvm.org/docs/ControlFlowIntegrity.html 819 820config CFI_PERMISSIVE 821 bool "Use CFI in permissive mode" 822 depends on CFI_CLANG 823 help 824 When selected, Control Flow Integrity (CFI) violations result in a 825 warning instead of a kernel panic. This option should only be used 826 for finding indirect call type mismatches during development. 827 828 If unsure, say N. 829 830config HAVE_ARCH_WITHIN_STACK_FRAMES 831 bool 832 help 833 An architecture should select this if it can walk the kernel stack 834 frames to determine if an object is part of either the arguments 835 or local variables (i.e. that it excludes saved return addresses, 836 and similar) by implementing an inline arch_within_stack_frames(), 837 which is used by CONFIG_HARDENED_USERCOPY. 838 839config HAVE_CONTEXT_TRACKING_USER 840 bool 841 help 842 Provide kernel/user boundaries probes necessary for subsystems 843 that need it, such as userspace RCU extended quiescent state. 844 Syscalls need to be wrapped inside user_exit()-user_enter(), either 845 optimized behind static key or through the slow path using TIF_NOHZ 846 flag. Exceptions handlers must be wrapped as well. Irqs are already 847 protected inside ct_irq_enter/ct_irq_exit() but preemption or signal 848 handling on irq exit still need to be protected. 849 850config HAVE_CONTEXT_TRACKING_USER_OFFSTACK 851 bool 852 help 853 Architecture neither relies on exception_enter()/exception_exit() 854 nor on schedule_user(). Also preempt_schedule_notrace() and 855 preempt_schedule_irq() can't be called in a preemptible section 856 while context tracking is CONTEXT_USER. This feature reflects a sane 857 entry implementation where the following requirements are met on 858 critical entry code, ie: before user_exit() or after user_enter(): 859 860 - Critical entry code isn't preemptible (or better yet: 861 not interruptible). 862 - No use of RCU read side critical sections, unless ct_nmi_enter() 863 got called. 864 - No use of instrumentation, unless instrumentation_begin() got 865 called. 866 867config HAVE_TIF_NOHZ 868 bool 869 help 870 Arch relies on TIF_NOHZ and syscall slow path to implement context 871 tracking calls to user_enter()/user_exit(). 872 873config HAVE_VIRT_CPU_ACCOUNTING 874 bool 875 876config HAVE_VIRT_CPU_ACCOUNTING_IDLE 877 bool 878 help 879 Architecture has its own way to account idle CPU time and therefore 880 doesn't implement vtime_account_idle(). 881 882config ARCH_HAS_SCALED_CPUTIME 883 bool 884 885config HAVE_VIRT_CPU_ACCOUNTING_GEN 886 bool 887 default y if 64BIT 888 help 889 With VIRT_CPU_ACCOUNTING_GEN, cputime_t becomes 64-bit. 890 Before enabling this option, arch code must be audited 891 to ensure there are no races in concurrent read/write of 892 cputime_t. For example, reading/writing 64-bit cputime_t on 893 some 32-bit arches may require multiple accesses, so proper 894 locking is needed to protect against concurrent accesses. 895 896config HAVE_IRQ_TIME_ACCOUNTING 897 bool 898 help 899 Archs need to ensure they use a high enough resolution clock to 900 support irq time accounting and then call enable_sched_clock_irqtime(). 901 902config HAVE_MOVE_PUD 903 bool 904 help 905 Architectures that select this are able to move page tables at the 906 PUD level. If there are only 3 page table levels, the move effectively 907 happens at the PGD level. 908 909config HAVE_MOVE_PMD 910 bool 911 help 912 Archs that select this are able to move page tables at the PMD level. 913 914config HAVE_ARCH_TRANSPARENT_HUGEPAGE 915 bool 916 917config HAVE_ARCH_TRANSPARENT_HUGEPAGE_PUD 918 bool 919 920config HAVE_ARCH_HUGE_VMAP 921 bool 922 923# 924# Archs that select this would be capable of PMD-sized vmaps (i.e., 925# arch_vmap_pmd_supported() returns true). The VM_ALLOW_HUGE_VMAP flag 926# must be used to enable allocations to use hugepages. 927# 928config HAVE_ARCH_HUGE_VMALLOC 929 depends on HAVE_ARCH_HUGE_VMAP 930 bool 931 932config ARCH_WANT_HUGE_PMD_SHARE 933 bool 934 935# Archs that want to use pmd_mkwrite on kernel memory need it defined even 936# if there are no userspace memory management features that use it 937config ARCH_WANT_KERNEL_PMD_MKWRITE 938 bool 939 940config ARCH_WANT_PMD_MKWRITE 941 def_bool TRANSPARENT_HUGEPAGE || ARCH_WANT_KERNEL_PMD_MKWRITE 942 943config HAVE_ARCH_SOFT_DIRTY 944 bool 945 946config HAVE_MOD_ARCH_SPECIFIC 947 bool 948 help 949 The arch uses struct mod_arch_specific to store data. Many arches 950 just need a simple module loader without arch specific data - those 951 should not enable this. 952 953config MODULES_USE_ELF_RELA 954 bool 955 help 956 Modules only use ELF RELA relocations. Modules with ELF REL 957 relocations will give an error. 958 959config MODULES_USE_ELF_REL 960 bool 961 help 962 Modules only use ELF REL relocations. Modules with ELF RELA 963 relocations will give an error. 964 965config ARCH_WANTS_MODULES_DATA_IN_VMALLOC 966 bool 967 help 968 For architectures like powerpc/32 which have constraints on module 969 allocation and need to allocate module data outside of module area. 970 971config HAVE_IRQ_EXIT_ON_IRQ_STACK 972 bool 973 help 974 Architecture doesn't only execute the irq handler on the irq stack 975 but also irq_exit(). This way we can process softirqs on this irq 976 stack instead of switching to a new one when we call __do_softirq() 977 in the end of an hardirq. 978 This spares a stack switch and improves cache usage on softirq 979 processing. 980 981config HAVE_SOFTIRQ_ON_OWN_STACK 982 bool 983 help 984 Architecture provides a function to run __do_softirq() on a 985 separate stack. 986 987config SOFTIRQ_ON_OWN_STACK 988 def_bool HAVE_SOFTIRQ_ON_OWN_STACK && !PREEMPT_RT 989 990config ALTERNATE_USER_ADDRESS_SPACE 991 bool 992 help 993 Architectures set this when the CPU uses separate address 994 spaces for kernel and user space pointers. In this case, the 995 access_ok() check on a __user pointer is skipped. 996 997config PGTABLE_LEVELS 998 int 999 default 2 1000 1001config ARCH_HAS_ELF_RANDOMIZE 1002 bool 1003 help 1004 An architecture supports choosing randomized locations for 1005 stack, mmap, brk, and ET_DYN. Defined functions: 1006 - arch_mmap_rnd() 1007 - arch_randomize_brk() 1008 1009config HAVE_ARCH_MMAP_RND_BITS 1010 bool 1011 help 1012 An arch should select this symbol if it supports setting a variable 1013 number of bits for use in establishing the base address for mmap 1014 allocations, has MMU enabled and provides values for both: 1015 - ARCH_MMAP_RND_BITS_MIN 1016 - ARCH_MMAP_RND_BITS_MAX 1017 1018config HAVE_EXIT_THREAD 1019 bool 1020 help 1021 An architecture implements exit_thread. 1022 1023config ARCH_MMAP_RND_BITS_MIN 1024 int 1025 1026config ARCH_MMAP_RND_BITS_MAX 1027 int 1028 1029config ARCH_MMAP_RND_BITS_DEFAULT 1030 int 1031 1032config ARCH_MMAP_RND_BITS 1033 int "Number of bits to use for ASLR of mmap base address" if EXPERT 1034 range ARCH_MMAP_RND_BITS_MIN ARCH_MMAP_RND_BITS_MAX 1035 default ARCH_MMAP_RND_BITS_DEFAULT if ARCH_MMAP_RND_BITS_DEFAULT 1036 default ARCH_MMAP_RND_BITS_MIN 1037 depends on HAVE_ARCH_MMAP_RND_BITS 1038 help 1039 This value can be used to select the number of bits to use to 1040 determine the random offset to the base address of vma regions 1041 resulting from mmap allocations. This value will be bounded 1042 by the architecture's minimum and maximum supported values. 1043 1044 This value can be changed after boot using the 1045 /proc/sys/vm/mmap_rnd_bits tunable 1046 1047config HAVE_ARCH_MMAP_RND_COMPAT_BITS 1048 bool 1049 help 1050 An arch should select this symbol if it supports running applications 1051 in compatibility mode, supports setting a variable number of bits for 1052 use in establishing the base address for mmap allocations, has MMU 1053 enabled and provides values for both: 1054 - ARCH_MMAP_RND_COMPAT_BITS_MIN 1055 - ARCH_MMAP_RND_COMPAT_BITS_MAX 1056 1057config ARCH_MMAP_RND_COMPAT_BITS_MIN 1058 int 1059 1060config ARCH_MMAP_RND_COMPAT_BITS_MAX 1061 int 1062 1063config ARCH_MMAP_RND_COMPAT_BITS_DEFAULT 1064 int 1065 1066config ARCH_MMAP_RND_COMPAT_BITS 1067 int "Number of bits to use for ASLR of mmap base address for compatible applications" if EXPERT 1068 range ARCH_MMAP_RND_COMPAT_BITS_MIN ARCH_MMAP_RND_COMPAT_BITS_MAX 1069 default ARCH_MMAP_RND_COMPAT_BITS_DEFAULT if ARCH_MMAP_RND_COMPAT_BITS_DEFAULT 1070 default ARCH_MMAP_RND_COMPAT_BITS_MIN 1071 depends on HAVE_ARCH_MMAP_RND_COMPAT_BITS 1072 help 1073 This value can be used to select the number of bits to use to 1074 determine the random offset to the base address of vma regions 1075 resulting from mmap allocations for compatible applications This 1076 value will be bounded by the architecture's minimum and maximum 1077 supported values. 1078 1079 This value can be changed after boot using the 1080 /proc/sys/vm/mmap_rnd_compat_bits tunable 1081 1082config HAVE_ARCH_COMPAT_MMAP_BASES 1083 bool 1084 help 1085 This allows 64bit applications to invoke 32-bit mmap() syscall 1086 and vice-versa 32-bit applications to call 64-bit mmap(). 1087 Required for applications doing different bitness syscalls. 1088 1089config PAGE_SIZE_LESS_THAN_64KB 1090 def_bool y 1091 depends on !ARM64_64K_PAGES 1092 depends on !IA64_PAGE_SIZE_64KB 1093 depends on !PAGE_SIZE_64KB 1094 depends on !PARISC_PAGE_SIZE_64KB 1095 depends on PAGE_SIZE_LESS_THAN_256KB 1096 1097config PAGE_SIZE_LESS_THAN_256KB 1098 def_bool y 1099 depends on !PAGE_SIZE_256KB 1100 1101# This allows to use a set of generic functions to determine mmap base 1102# address by giving priority to top-down scheme only if the process 1103# is not in legacy mode (compat task, unlimited stack size or 1104# sysctl_legacy_va_layout). 1105# Architecture that selects this option can provide its own version of: 1106# - STACK_RND_MASK 1107config ARCH_WANT_DEFAULT_TOPDOWN_MMAP_LAYOUT 1108 bool 1109 depends on MMU 1110 select ARCH_HAS_ELF_RANDOMIZE 1111 1112config HAVE_OBJTOOL 1113 bool 1114 1115config HAVE_JUMP_LABEL_HACK 1116 bool 1117 1118config HAVE_NOINSTR_HACK 1119 bool 1120 1121config HAVE_NOINSTR_VALIDATION 1122 bool 1123 1124config HAVE_UACCESS_VALIDATION 1125 bool 1126 select OBJTOOL 1127 1128config HAVE_STACK_VALIDATION 1129 bool 1130 help 1131 Architecture supports objtool compile-time frame pointer rule 1132 validation. 1133 1134config HAVE_RELIABLE_STACKTRACE 1135 bool 1136 help 1137 Architecture has either save_stack_trace_tsk_reliable() or 1138 arch_stack_walk_reliable() function which only returns a stack trace 1139 if it can guarantee the trace is reliable. 1140 1141config HAVE_ARCH_HASH 1142 bool 1143 default n 1144 help 1145 If this is set, the architecture provides an <asm/hash.h> 1146 file which provides platform-specific implementations of some 1147 functions in <linux/hash.h> or fs/namei.c. 1148 1149config HAVE_ARCH_NVRAM_OPS 1150 bool 1151 1152config ISA_BUS_API 1153 def_bool ISA 1154 1155# 1156# ABI hall of shame 1157# 1158config CLONE_BACKWARDS 1159 bool 1160 help 1161 Architecture has tls passed as the 4th argument of clone(2), 1162 not the 5th one. 1163 1164config CLONE_BACKWARDS2 1165 bool 1166 help 1167 Architecture has the first two arguments of clone(2) swapped. 1168 1169config CLONE_BACKWARDS3 1170 bool 1171 help 1172 Architecture has tls passed as the 3rd argument of clone(2), 1173 not the 5th one. 1174 1175config ODD_RT_SIGACTION 1176 bool 1177 help 1178 Architecture has unusual rt_sigaction(2) arguments 1179 1180config OLD_SIGSUSPEND 1181 bool 1182 help 1183 Architecture has old sigsuspend(2) syscall, of one-argument variety 1184 1185config OLD_SIGSUSPEND3 1186 bool 1187 help 1188 Even weirder antique ABI - three-argument sigsuspend(2) 1189 1190config OLD_SIGACTION 1191 bool 1192 help 1193 Architecture has old sigaction(2) syscall. Nope, not the same 1194 as OLD_SIGSUSPEND | OLD_SIGSUSPEND3 - alpha has sigsuspend(2), 1195 but fairly different variant of sigaction(2), thanks to OSF/1 1196 compatibility... 1197 1198config COMPAT_OLD_SIGACTION 1199 bool 1200 1201config COMPAT_32BIT_TIME 1202 bool "Provide system calls for 32-bit time_t" 1203 default !64BIT || COMPAT 1204 help 1205 This enables 32 bit time_t support in addition to 64 bit time_t support. 1206 This is relevant on all 32-bit architectures, and 64-bit architectures 1207 as part of compat syscall handling. 1208 1209config ARCH_NO_PREEMPT 1210 bool 1211 1212config ARCH_SUPPORTS_RT 1213 bool 1214 1215config CPU_NO_EFFICIENT_FFS 1216 def_bool n 1217 1218config HAVE_ARCH_VMAP_STACK 1219 def_bool n 1220 help 1221 An arch should select this symbol if it can support kernel stacks 1222 in vmalloc space. This means: 1223 1224 - vmalloc space must be large enough to hold many kernel stacks. 1225 This may rule out many 32-bit architectures. 1226 1227 - Stacks in vmalloc space need to work reliably. For example, if 1228 vmap page tables are created on demand, either this mechanism 1229 needs to work while the stack points to a virtual address with 1230 unpopulated page tables or arch code (switch_to() and switch_mm(), 1231 most likely) needs to ensure that the stack's page table entries 1232 are populated before running on a possibly unpopulated stack. 1233 1234 - If the stack overflows into a guard page, something reasonable 1235 should happen. The definition of "reasonable" is flexible, but 1236 instantly rebooting without logging anything would be unfriendly. 1237 1238config VMAP_STACK 1239 default y 1240 bool "Use a virtually-mapped stack" 1241 depends on HAVE_ARCH_VMAP_STACK 1242 depends on !KASAN || KASAN_HW_TAGS || KASAN_VMALLOC 1243 help 1244 Enable this if you want the use virtually-mapped kernel stacks 1245 with guard pages. This causes kernel stack overflows to be 1246 caught immediately rather than causing difficult-to-diagnose 1247 corruption. 1248 1249 To use this with software KASAN modes, the architecture must support 1250 backing virtual mappings with real shadow memory, and KASAN_VMALLOC 1251 must be enabled. 1252 1253config HAVE_ARCH_RANDOMIZE_KSTACK_OFFSET 1254 def_bool n 1255 help 1256 An arch should select this symbol if it can support kernel stack 1257 offset randomization with calls to add_random_kstack_offset() 1258 during syscall entry and choose_random_kstack_offset() during 1259 syscall exit. Careful removal of -fstack-protector-strong and 1260 -fstack-protector should also be applied to the entry code and 1261 closely examined, as the artificial stack bump looks like an array 1262 to the compiler, so it will attempt to add canary checks regardless 1263 of the static branch state. 1264 1265config RANDOMIZE_KSTACK_OFFSET 1266 bool "Support for randomizing kernel stack offset on syscall entry" if EXPERT 1267 default y 1268 depends on HAVE_ARCH_RANDOMIZE_KSTACK_OFFSET 1269 depends on INIT_STACK_NONE || !CC_IS_CLANG || CLANG_VERSION >= 140000 1270 help 1271 The kernel stack offset can be randomized (after pt_regs) by 1272 roughly 5 bits of entropy, frustrating memory corruption 1273 attacks that depend on stack address determinism or 1274 cross-syscall address exposures. 1275 1276 The feature is controlled via the "randomize_kstack_offset=on/off" 1277 kernel boot param, and if turned off has zero overhead due to its use 1278 of static branches (see JUMP_LABEL). 1279 1280 If unsure, say Y. 1281 1282config RANDOMIZE_KSTACK_OFFSET_DEFAULT 1283 bool "Default state of kernel stack offset randomization" 1284 depends on RANDOMIZE_KSTACK_OFFSET 1285 help 1286 Kernel stack offset randomization is controlled by kernel boot param 1287 "randomize_kstack_offset=on/off", and this config chooses the default 1288 boot state. 1289 1290config ARCH_OPTIONAL_KERNEL_RWX 1291 def_bool n 1292 1293config ARCH_OPTIONAL_KERNEL_RWX_DEFAULT 1294 def_bool n 1295 1296config ARCH_HAS_STRICT_KERNEL_RWX 1297 def_bool n 1298 1299config STRICT_KERNEL_RWX 1300 bool "Make kernel text and rodata read-only" if ARCH_OPTIONAL_KERNEL_RWX 1301 depends on ARCH_HAS_STRICT_KERNEL_RWX 1302 default !ARCH_OPTIONAL_KERNEL_RWX || ARCH_OPTIONAL_KERNEL_RWX_DEFAULT 1303 help 1304 If this is set, kernel text and rodata memory will be made read-only, 1305 and non-text memory will be made non-executable. This provides 1306 protection against certain security exploits (e.g. executing the heap 1307 or modifying text) 1308 1309 These features are considered standard security practice these days. 1310 You should say Y here in almost all cases. 1311 1312config ARCH_HAS_STRICT_MODULE_RWX 1313 def_bool n 1314 1315config STRICT_MODULE_RWX 1316 bool "Set loadable kernel module data as NX and text as RO" if ARCH_OPTIONAL_KERNEL_RWX 1317 depends on ARCH_HAS_STRICT_MODULE_RWX && MODULES 1318 default !ARCH_OPTIONAL_KERNEL_RWX || ARCH_OPTIONAL_KERNEL_RWX_DEFAULT 1319 help 1320 If this is set, module text and rodata memory will be made read-only, 1321 and non-text memory will be made non-executable. This provides 1322 protection against certain security exploits (e.g. writing to text) 1323 1324# select if the architecture provides an asm/dma-direct.h header 1325config ARCH_HAS_PHYS_TO_DMA 1326 bool 1327 1328config HAVE_ARCH_COMPILER_H 1329 bool 1330 help 1331 An architecture can select this if it provides an 1332 asm/compiler.h header that should be included after 1333 linux/compiler-*.h in order to override macro definitions that those 1334 headers generally provide. 1335 1336config HAVE_ARCH_PREL32_RELOCATIONS 1337 bool 1338 help 1339 May be selected by an architecture if it supports place-relative 1340 32-bit relocations, both in the toolchain and in the module loader, 1341 in which case relative references can be used in special sections 1342 for PCI fixup, initcalls etc which are only half the size on 64 bit 1343 architectures, and don't require runtime relocation on relocatable 1344 kernels. 1345 1346config ARCH_USE_MEMREMAP_PROT 1347 bool 1348 1349config LOCK_EVENT_COUNTS 1350 bool "Locking event counts collection" 1351 depends on DEBUG_FS 1352 help 1353 Enable light-weight counting of various locking related events 1354 in the system with minimal performance impact. This reduces 1355 the chance of application behavior change because of timing 1356 differences. The counts are reported via debugfs. 1357 1358# Select if the architecture has support for applying RELR relocations. 1359config ARCH_HAS_RELR 1360 bool 1361 1362config RELR 1363 bool "Use RELR relocation packing" 1364 depends on ARCH_HAS_RELR && TOOLS_SUPPORT_RELR 1365 default y 1366 help 1367 Store the kernel's dynamic relocations in the RELR relocation packing 1368 format. Requires a compatible linker (LLD supports this feature), as 1369 well as compatible NM and OBJCOPY utilities (llvm-nm and llvm-objcopy 1370 are compatible). 1371 1372config ARCH_HAS_MEM_ENCRYPT 1373 bool 1374 1375config ARCH_HAS_CC_PLATFORM 1376 bool 1377 1378config HAVE_SPARSE_SYSCALL_NR 1379 bool 1380 help 1381 An architecture should select this if its syscall numbering is sparse 1382 to save space. For example, MIPS architecture has a syscall array with 1383 entries at 4000, 5000 and 6000 locations. This option turns on syscall 1384 related optimizations for a given architecture. 1385 1386config ARCH_HAS_VDSO_DATA 1387 bool 1388 1389config HAVE_STATIC_CALL 1390 bool 1391 1392config HAVE_STATIC_CALL_INLINE 1393 bool 1394 depends on HAVE_STATIC_CALL 1395 select OBJTOOL 1396 1397config HAVE_PREEMPT_DYNAMIC 1398 bool 1399 1400config HAVE_PREEMPT_DYNAMIC_CALL 1401 bool 1402 depends on HAVE_STATIC_CALL 1403 select HAVE_PREEMPT_DYNAMIC 1404 help 1405 An architecture should select this if it can handle the preemption 1406 model being selected at boot time using static calls. 1407 1408 Where an architecture selects HAVE_STATIC_CALL_INLINE, any call to a 1409 preemption function will be patched directly. 1410 1411 Where an architecture does not select HAVE_STATIC_CALL_INLINE, any 1412 call to a preemption function will go through a trampoline, and the 1413 trampoline will be patched. 1414 1415 It is strongly advised to support inline static call to avoid any 1416 overhead. 1417 1418config HAVE_PREEMPT_DYNAMIC_KEY 1419 bool 1420 depends on HAVE_ARCH_JUMP_LABEL 1421 select HAVE_PREEMPT_DYNAMIC 1422 help 1423 An architecture should select this if it can handle the preemption 1424 model being selected at boot time using static keys. 1425 1426 Each preemption function will be given an early return based on a 1427 static key. This should have slightly lower overhead than non-inline 1428 static calls, as this effectively inlines each trampoline into the 1429 start of its callee. This may avoid redundant work, and may 1430 integrate better with CFI schemes. 1431 1432 This will have greater overhead than using inline static calls as 1433 the call to the preemption function cannot be entirely elided. 1434 1435config ARCH_WANT_LD_ORPHAN_WARN 1436 bool 1437 help 1438 An arch should select this symbol once all linker sections are explicitly 1439 included, size-asserted, or discarded in the linker scripts. This is 1440 important because we never want expected sections to be placed heuristically 1441 by the linker, since the locations of such sections can change between linker 1442 versions. 1443 1444config HAVE_ARCH_PFN_VALID 1445 bool 1446 1447config ARCH_SUPPORTS_DEBUG_PAGEALLOC 1448 bool 1449 1450config ARCH_SUPPORTS_PAGE_TABLE_CHECK 1451 bool 1452 1453config ARCH_SPLIT_ARG64 1454 bool 1455 help 1456 If a 32-bit architecture requires 64-bit arguments to be split into 1457 pairs of 32-bit arguments, select this option. 1458 1459config ARCH_HAS_ELFCORE_COMPAT 1460 bool 1461 1462config ARCH_HAS_PARANOID_L1D_FLUSH 1463 bool 1464 1465config ARCH_HAVE_TRACE_MMIO_ACCESS 1466 bool 1467 1468config DYNAMIC_SIGFRAME 1469 bool 1470 1471# Select, if arch has a named attribute group bound to NUMA device nodes. 1472config HAVE_ARCH_NODE_DEV_GROUP 1473 bool 1474 1475config ARCH_HAS_NONLEAF_PMD_YOUNG 1476 bool 1477 help 1478 Architectures that select this option are capable of setting the 1479 accessed bit in non-leaf PMD entries when using them as part of linear 1480 address translations. Page table walkers that clear the accessed bit 1481 may use this capability to reduce their search space. 1482 1483source "kernel/gcov/Kconfig" 1484 1485source "scripts/gcc-plugins/Kconfig" 1486 1487config FUNCTION_ALIGNMENT_4B 1488 bool 1489 1490config FUNCTION_ALIGNMENT_8B 1491 bool 1492 1493config FUNCTION_ALIGNMENT_16B 1494 bool 1495 1496config FUNCTION_ALIGNMENT_32B 1497 bool 1498 1499config FUNCTION_ALIGNMENT_64B 1500 bool 1501 1502config FUNCTION_ALIGNMENT 1503 int 1504 default 64 if FUNCTION_ALIGNMENT_64B 1505 default 32 if FUNCTION_ALIGNMENT_32B 1506 default 16 if FUNCTION_ALIGNMENT_16B 1507 default 8 if FUNCTION_ALIGNMENT_8B 1508 default 4 if FUNCTION_ALIGNMENT_4B 1509 default 0 1510 1511endmenu 1512