1# SPDX-License-Identifier: GPL-2.0 2# 3# General architecture dependent options 4# 5 6# 7# Note: arch/$(SRCARCH)/Kconfig needs to be included first so that it can 8# override the default values in this file. 9# 10source "arch/$(SRCARCH)/Kconfig" 11 12menu "General architecture-dependent options" 13 14config CRASH_CORE 15 bool 16 17config KEXEC_CORE 18 select CRASH_CORE 19 bool 20 21config KEXEC_ELF 22 bool 23 24config HAVE_IMA_KEXEC 25 bool 26 27config ARCH_HAS_SUBPAGE_FAULTS 28 bool 29 help 30 Select if the architecture can check permissions at sub-page 31 granularity (e.g. arm64 MTE). The probe_user_*() functions 32 must be implemented. 33 34config HOTPLUG_SMT 35 bool 36 37config GENERIC_ENTRY 38 bool 39 40config KPROBES 41 bool "Kprobes" 42 depends on MODULES 43 depends on HAVE_KPROBES 44 select KALLSYMS 45 select TASKS_RCU if PREEMPTION 46 help 47 Kprobes allows you to trap at almost any kernel address and 48 execute a callback function. register_kprobe() establishes 49 a probepoint and specifies the callback. Kprobes is useful 50 for kernel debugging, non-intrusive instrumentation and testing. 51 If in doubt, say "N". 52 53config JUMP_LABEL 54 bool "Optimize very unlikely/likely branches" 55 depends on HAVE_ARCH_JUMP_LABEL 56 select OBJTOOL if HAVE_JUMP_LABEL_HACK 57 help 58 This option enables a transparent branch optimization that 59 makes certain almost-always-true or almost-always-false branch 60 conditions even cheaper to execute within the kernel. 61 62 Certain performance-sensitive kernel code, such as trace points, 63 scheduler functionality, networking code and KVM have such 64 branches and include support for this optimization technique. 65 66 If it is detected that the compiler has support for "asm goto", 67 the kernel will compile such branches with just a nop 68 instruction. When the condition flag is toggled to true, the 69 nop will be converted to a jump instruction to execute the 70 conditional block of instructions. 71 72 This technique lowers overhead and stress on the branch prediction 73 of the processor and generally makes the kernel faster. The update 74 of the condition is slower, but those are always very rare. 75 76 ( On 32-bit x86, the necessary options added to the compiler 77 flags may increase the size of the kernel slightly. ) 78 79config STATIC_KEYS_SELFTEST 80 bool "Static key selftest" 81 depends on JUMP_LABEL 82 help 83 Boot time self-test of the branch patching code. 84 85config STATIC_CALL_SELFTEST 86 bool "Static call selftest" 87 depends on HAVE_STATIC_CALL 88 help 89 Boot time self-test of the call patching code. 90 91config OPTPROBES 92 def_bool y 93 depends on KPROBES && HAVE_OPTPROBES 94 select TASKS_RCU if PREEMPTION 95 96config KPROBES_ON_FTRACE 97 def_bool y 98 depends on KPROBES && HAVE_KPROBES_ON_FTRACE 99 depends on DYNAMIC_FTRACE_WITH_REGS 100 help 101 If function tracer is enabled and the arch supports full 102 passing of pt_regs to function tracing, then kprobes can 103 optimize on top of function tracing. 104 105config UPROBES 106 def_bool n 107 depends on ARCH_SUPPORTS_UPROBES 108 help 109 Uprobes is the user-space counterpart to kprobes: they 110 enable instrumentation applications (such as 'perf probe') 111 to establish unintrusive probes in user-space binaries and 112 libraries, by executing handler functions when the probes 113 are hit by user-space applications. 114 115 ( These probes come in the form of single-byte breakpoints, 116 managed by the kernel and kept transparent to the probed 117 application. ) 118 119config HAVE_64BIT_ALIGNED_ACCESS 120 def_bool 64BIT && !HAVE_EFFICIENT_UNALIGNED_ACCESS 121 help 122 Some architectures require 64 bit accesses to be 64 bit 123 aligned, which also requires structs containing 64 bit values 124 to be 64 bit aligned too. This includes some 32 bit 125 architectures which can do 64 bit accesses, as well as 64 bit 126 architectures without unaligned access. 127 128 This symbol should be selected by an architecture if 64 bit 129 accesses are required to be 64 bit aligned in this way even 130 though it is not a 64 bit architecture. 131 132 See Documentation/core-api/unaligned-memory-access.rst for 133 more information on the topic of unaligned memory accesses. 134 135config HAVE_EFFICIENT_UNALIGNED_ACCESS 136 bool 137 help 138 Some architectures are unable to perform unaligned accesses 139 without the use of get_unaligned/put_unaligned. Others are 140 unable to perform such accesses efficiently (e.g. trap on 141 unaligned access and require fixing it up in the exception 142 handler.) 143 144 This symbol should be selected by an architecture if it can 145 perform unaligned accesses efficiently to allow different 146 code paths to be selected for these cases. Some network 147 drivers, for example, could opt to not fix up alignment 148 problems with received packets if doing so would not help 149 much. 150 151 See Documentation/core-api/unaligned-memory-access.rst for more 152 information on the topic of unaligned memory accesses. 153 154config ARCH_USE_BUILTIN_BSWAP 155 bool 156 help 157 Modern versions of GCC (since 4.4) have builtin functions 158 for handling byte-swapping. Using these, instead of the old 159 inline assembler that the architecture code provides in the 160 __arch_bswapXX() macros, allows the compiler to see what's 161 happening and offers more opportunity for optimisation. In 162 particular, the compiler will be able to combine the byteswap 163 with a nearby load or store and use load-and-swap or 164 store-and-swap instructions if the architecture has them. It 165 should almost *never* result in code which is worse than the 166 hand-coded assembler in <asm/swab.h>. But just in case it 167 does, the use of the builtins is optional. 168 169 Any architecture with load-and-swap or store-and-swap 170 instructions should set this. And it shouldn't hurt to set it 171 on architectures that don't have such instructions. 172 173config KRETPROBES 174 def_bool y 175 depends on KPROBES && (HAVE_KRETPROBES || HAVE_RETHOOK) 176 177config KRETPROBE_ON_RETHOOK 178 def_bool y 179 depends on HAVE_RETHOOK 180 depends on KRETPROBES 181 select RETHOOK 182 183config USER_RETURN_NOTIFIER 184 bool 185 depends on HAVE_USER_RETURN_NOTIFIER 186 help 187 Provide a kernel-internal notification when a cpu is about to 188 switch to user mode. 189 190config HAVE_IOREMAP_PROT 191 bool 192 193config HAVE_KPROBES 194 bool 195 196config HAVE_KRETPROBES 197 bool 198 199config HAVE_OPTPROBES 200 bool 201 202config HAVE_KPROBES_ON_FTRACE 203 bool 204 205config ARCH_CORRECT_STACKTRACE_ON_KRETPROBE 206 bool 207 help 208 Since kretprobes modifies return address on the stack, the 209 stacktrace may see the kretprobe trampoline address instead 210 of correct one. If the architecture stacktrace code and 211 unwinder can adjust such entries, select this configuration. 212 213config HAVE_FUNCTION_ERROR_INJECTION 214 bool 215 216config HAVE_NMI 217 bool 218 219config HAVE_FUNCTION_DESCRIPTORS 220 bool 221 222config TRACE_IRQFLAGS_SUPPORT 223 bool 224 225config TRACE_IRQFLAGS_NMI_SUPPORT 226 bool 227 228# 229# An arch should select this if it provides all these things: 230# 231# task_pt_regs() in asm/processor.h or asm/ptrace.h 232# arch_has_single_step() if there is hardware single-step support 233# arch_has_block_step() if there is hardware block-step support 234# asm/syscall.h supplying asm-generic/syscall.h interface 235# linux/regset.h user_regset interfaces 236# CORE_DUMP_USE_REGSET #define'd in linux/elf.h 237# TIF_SYSCALL_TRACE calls ptrace_report_syscall_{entry,exit} 238# TIF_NOTIFY_RESUME calls resume_user_mode_work() 239# 240config HAVE_ARCH_TRACEHOOK 241 bool 242 243config HAVE_DMA_CONTIGUOUS 244 bool 245 246config GENERIC_SMP_IDLE_THREAD 247 bool 248 249config GENERIC_IDLE_POLL_SETUP 250 bool 251 252config ARCH_HAS_FORTIFY_SOURCE 253 bool 254 help 255 An architecture should select this when it can successfully 256 build and run with CONFIG_FORTIFY_SOURCE. 257 258# 259# Select if the arch provides a historic keepinit alias for the retain_initrd 260# command line option 261# 262config ARCH_HAS_KEEPINITRD 263 bool 264 265# Select if arch has all set_memory_ro/rw/x/nx() functions in asm/cacheflush.h 266config ARCH_HAS_SET_MEMORY 267 bool 268 269# Select if arch has all set_direct_map_invalid/default() functions 270config ARCH_HAS_SET_DIRECT_MAP 271 bool 272 273# 274# Select if the architecture provides the arch_dma_set_uncached symbol to 275# either provide an uncached segment alias for a DMA allocation, or 276# to remap the page tables in place. 277# 278config ARCH_HAS_DMA_SET_UNCACHED 279 bool 280 281# 282# Select if the architectures provides the arch_dma_clear_uncached symbol 283# to undo an in-place page table remap for uncached access. 284# 285config ARCH_HAS_DMA_CLEAR_UNCACHED 286 bool 287 288config ARCH_HAS_CPU_FINALIZE_INIT 289 bool 290 291# Select if arch init_task must go in the __init_task_data section 292config ARCH_TASK_STRUCT_ON_STACK 293 bool 294 295# Select if arch has its private alloc_task_struct() function 296config ARCH_TASK_STRUCT_ALLOCATOR 297 bool 298 299config HAVE_ARCH_THREAD_STRUCT_WHITELIST 300 bool 301 depends on !ARCH_TASK_STRUCT_ALLOCATOR 302 help 303 An architecture should select this to provide hardened usercopy 304 knowledge about what region of the thread_struct should be 305 whitelisted for copying to userspace. Normally this is only the 306 FPU registers. Specifically, arch_thread_struct_whitelist() 307 should be implemented. Without this, the entire thread_struct 308 field in task_struct will be left whitelisted. 309 310# Select if arch has its private alloc_thread_stack() function 311config ARCH_THREAD_STACK_ALLOCATOR 312 bool 313 314# Select if arch wants to size task_struct dynamically via arch_task_struct_size: 315config ARCH_WANTS_DYNAMIC_TASK_STRUCT 316 bool 317 318config ARCH_WANTS_NO_INSTR 319 bool 320 help 321 An architecture should select this if the noinstr macro is being used on 322 functions to denote that the toolchain should avoid instrumenting such 323 functions and is required for correctness. 324 325config ARCH_32BIT_OFF_T 326 bool 327 depends on !64BIT 328 help 329 All new 32-bit architectures should have 64-bit off_t type on 330 userspace side which corresponds to the loff_t kernel type. This 331 is the requirement for modern ABIs. Some existing architectures 332 still support 32-bit off_t. This option is enabled for all such 333 architectures explicitly. 334 335# Selected by 64 bit architectures which have a 32 bit f_tinode in struct ustat 336config ARCH_32BIT_USTAT_F_TINODE 337 bool 338 339config HAVE_ASM_MODVERSIONS 340 bool 341 help 342 This symbol should be selected by an architecture if it provides 343 <asm/asm-prototypes.h> to support the module versioning for symbols 344 exported from assembly code. 345 346config HAVE_REGS_AND_STACK_ACCESS_API 347 bool 348 help 349 This symbol should be selected by an architecture if it supports 350 the API needed to access registers and stack entries from pt_regs, 351 declared in asm/ptrace.h 352 For example the kprobes-based event tracer needs this API. 353 354config HAVE_RSEQ 355 bool 356 depends on HAVE_REGS_AND_STACK_ACCESS_API 357 help 358 This symbol should be selected by an architecture if it 359 supports an implementation of restartable sequences. 360 361config HAVE_RUST 362 bool 363 help 364 This symbol should be selected by an architecture if it 365 supports Rust. 366 367config HAVE_FUNCTION_ARG_ACCESS_API 368 bool 369 help 370 This symbol should be selected by an architecture if it supports 371 the API needed to access function arguments from pt_regs, 372 declared in asm/ptrace.h 373 374config HAVE_HW_BREAKPOINT 375 bool 376 depends on PERF_EVENTS 377 378config HAVE_MIXED_BREAKPOINTS_REGS 379 bool 380 depends on HAVE_HW_BREAKPOINT 381 help 382 Depending on the arch implementation of hardware breakpoints, 383 some of them have separate registers for data and instruction 384 breakpoints addresses, others have mixed registers to store 385 them but define the access type in a control register. 386 Select this option if your arch implements breakpoints under the 387 latter fashion. 388 389config HAVE_USER_RETURN_NOTIFIER 390 bool 391 392config HAVE_PERF_EVENTS_NMI 393 bool 394 help 395 System hardware can generate an NMI using the perf event 396 subsystem. Also has support for calculating CPU cycle events 397 to determine how many clock cycles in a given period. 398 399config HAVE_HARDLOCKUP_DETECTOR_PERF 400 bool 401 depends on HAVE_PERF_EVENTS_NMI 402 help 403 The arch chooses to use the generic perf-NMI-based hardlockup 404 detector. Must define HAVE_PERF_EVENTS_NMI. 405 406config HAVE_NMI_WATCHDOG 407 depends on HAVE_NMI 408 bool 409 help 410 The arch provides a low level NMI watchdog. It provides 411 asm/nmi.h, and defines its own arch_touch_nmi_watchdog(). 412 413config HAVE_HARDLOCKUP_DETECTOR_ARCH 414 bool 415 select HAVE_NMI_WATCHDOG 416 help 417 The arch chooses to provide its own hardlockup detector, which is 418 a superset of the HAVE_NMI_WATCHDOG. It also conforms to config 419 interfaces and parameters provided by hardlockup detector subsystem. 420 421config HAVE_PERF_REGS 422 bool 423 help 424 Support selective register dumps for perf events. This includes 425 bit-mapping of each registers and a unique architecture id. 426 427config HAVE_PERF_USER_STACK_DUMP 428 bool 429 help 430 Support user stack dumps for perf event samples. This needs 431 access to the user stack pointer which is not unified across 432 architectures. 433 434config HAVE_ARCH_JUMP_LABEL 435 bool 436 437config HAVE_ARCH_JUMP_LABEL_RELATIVE 438 bool 439 440config MMU_GATHER_TABLE_FREE 441 bool 442 443config MMU_GATHER_RCU_TABLE_FREE 444 bool 445 select MMU_GATHER_TABLE_FREE 446 447config MMU_GATHER_PAGE_SIZE 448 bool 449 450config MMU_GATHER_NO_RANGE 451 bool 452 select MMU_GATHER_MERGE_VMAS 453 454config MMU_GATHER_NO_FLUSH_CACHE 455 bool 456 457config MMU_GATHER_MERGE_VMAS 458 bool 459 460config MMU_GATHER_NO_GATHER 461 bool 462 depends on MMU_GATHER_TABLE_FREE 463 464config ARCH_WANT_IRQS_OFF_ACTIVATE_MM 465 bool 466 help 467 Temporary select until all architectures can be converted to have 468 irqs disabled over activate_mm. Architectures that do IPI based TLB 469 shootdowns should enable this. 470 471# Use normal mm refcounting for MMU_LAZY_TLB kernel thread references. 472# MMU_LAZY_TLB_REFCOUNT=n can improve the scalability of context switching 473# to/from kernel threads when the same mm is running on a lot of CPUs (a large 474# multi-threaded application), by reducing contention on the mm refcount. 475# 476# This can be disabled if the architecture ensures no CPUs are using an mm as a 477# "lazy tlb" beyond its final refcount (i.e., by the time __mmdrop frees the mm 478# or its kernel page tables). This could be arranged by arch_exit_mmap(), or 479# final exit(2) TLB flush, for example. 480# 481# To implement this, an arch *must*: 482# Ensure the _lazy_tlb variants of mmgrab/mmdrop are used when manipulating 483# the lazy tlb reference of a kthread's ->active_mm (non-arch code has been 484# converted already). 485config MMU_LAZY_TLB_REFCOUNT 486 def_bool y 487 depends on !MMU_LAZY_TLB_SHOOTDOWN 488 489# This option allows MMU_LAZY_TLB_REFCOUNT=n. It ensures no CPUs are using an 490# mm as a lazy tlb beyond its last reference count, by shooting down these 491# users before the mm is deallocated. __mmdrop() first IPIs all CPUs that may 492# be using the mm as a lazy tlb, so that they may switch themselves to using 493# init_mm for their active mm. mm_cpumask(mm) is used to determine which CPUs 494# may be using mm as a lazy tlb mm. 495# 496# To implement this, an arch *must*: 497# - At the time of the final mmdrop of the mm, ensure mm_cpumask(mm) contains 498# at least all possible CPUs in which the mm is lazy. 499# - It must meet the requirements for MMU_LAZY_TLB_REFCOUNT=n (see above). 500config MMU_LAZY_TLB_SHOOTDOWN 501 bool 502 503config ARCH_HAVE_NMI_SAFE_CMPXCHG 504 bool 505 506config ARCH_HAS_NMI_SAFE_THIS_CPU_OPS 507 bool 508 509config HAVE_ALIGNED_STRUCT_PAGE 510 bool 511 help 512 This makes sure that struct pages are double word aligned and that 513 e.g. the SLUB allocator can perform double word atomic operations 514 on a struct page for better performance. However selecting this 515 might increase the size of a struct page by a word. 516 517config HAVE_CMPXCHG_LOCAL 518 bool 519 520config HAVE_CMPXCHG_DOUBLE 521 bool 522 523config ARCH_WEAK_RELEASE_ACQUIRE 524 bool 525 526config ARCH_WANT_IPC_PARSE_VERSION 527 bool 528 529config ARCH_WANT_COMPAT_IPC_PARSE_VERSION 530 bool 531 532config ARCH_WANT_OLD_COMPAT_IPC 533 select ARCH_WANT_COMPAT_IPC_PARSE_VERSION 534 bool 535 536config HAVE_ARCH_SECCOMP 537 bool 538 help 539 An arch should select this symbol to support seccomp mode 1 (the fixed 540 syscall policy), and must provide an overrides for __NR_seccomp_sigreturn, 541 and compat syscalls if the asm-generic/seccomp.h defaults need adjustment: 542 - __NR_seccomp_read_32 543 - __NR_seccomp_write_32 544 - __NR_seccomp_exit_32 545 - __NR_seccomp_sigreturn_32 546 547config HAVE_ARCH_SECCOMP_FILTER 548 bool 549 select HAVE_ARCH_SECCOMP 550 help 551 An arch should select this symbol if it provides all of these things: 552 - all the requirements for HAVE_ARCH_SECCOMP 553 - syscall_get_arch() 554 - syscall_get_arguments() 555 - syscall_rollback() 556 - syscall_set_return_value() 557 - SIGSYS siginfo_t support 558 - secure_computing is called from a ptrace_event()-safe context 559 - secure_computing return value is checked and a return value of -1 560 results in the system call being skipped immediately. 561 - seccomp syscall wired up 562 - if !HAVE_SPARSE_SYSCALL_NR, have SECCOMP_ARCH_NATIVE, 563 SECCOMP_ARCH_NATIVE_NR, SECCOMP_ARCH_NATIVE_NAME defined. If 564 COMPAT is supported, have the SECCOMP_ARCH_COMPAT* defines too. 565 566config SECCOMP 567 prompt "Enable seccomp to safely execute untrusted bytecode" 568 def_bool y 569 depends on HAVE_ARCH_SECCOMP 570 help 571 This kernel feature is useful for number crunching applications 572 that may need to handle untrusted bytecode during their 573 execution. By using pipes or other transports made available 574 to the process as file descriptors supporting the read/write 575 syscalls, it's possible to isolate those applications in their 576 own address space using seccomp. Once seccomp is enabled via 577 prctl(PR_SET_SECCOMP) or the seccomp() syscall, it cannot be 578 disabled and the task is only allowed to execute a few safe 579 syscalls defined by each seccomp mode. 580 581 If unsure, say Y. 582 583config SECCOMP_FILTER 584 def_bool y 585 depends on HAVE_ARCH_SECCOMP_FILTER && SECCOMP && NET 586 help 587 Enable tasks to build secure computing environments defined 588 in terms of Berkeley Packet Filter programs which implement 589 task-defined system call filtering polices. 590 591 See Documentation/userspace-api/seccomp_filter.rst for details. 592 593config SECCOMP_CACHE_DEBUG 594 bool "Show seccomp filter cache status in /proc/pid/seccomp_cache" 595 depends on SECCOMP_FILTER && !HAVE_SPARSE_SYSCALL_NR 596 depends on PROC_FS 597 help 598 This enables the /proc/pid/seccomp_cache interface to monitor 599 seccomp cache data. The file format is subject to change. Reading 600 the file requires CAP_SYS_ADMIN. 601 602 This option is for debugging only. Enabling presents the risk that 603 an adversary may be able to infer the seccomp filter logic. 604 605 If unsure, say N. 606 607config HAVE_ARCH_STACKLEAK 608 bool 609 help 610 An architecture should select this if it has the code which 611 fills the used part of the kernel stack with the STACKLEAK_POISON 612 value before returning from system calls. 613 614config HAVE_STACKPROTECTOR 615 bool 616 help 617 An arch should select this symbol if: 618 - it has implemented a stack canary (e.g. __stack_chk_guard) 619 620config STACKPROTECTOR 621 bool "Stack Protector buffer overflow detection" 622 depends on HAVE_STACKPROTECTOR 623 depends on $(cc-option,-fstack-protector) 624 default y 625 help 626 This option turns on the "stack-protector" GCC feature. This 627 feature puts, at the beginning of functions, a canary value on 628 the stack just before the return address, and validates 629 the value just before actually returning. Stack based buffer 630 overflows (that need to overwrite this return address) now also 631 overwrite the canary, which gets detected and the attack is then 632 neutralized via a kernel panic. 633 634 Functions will have the stack-protector canary logic added if they 635 have an 8-byte or larger character array on the stack. 636 637 This feature requires gcc version 4.2 or above, or a distribution 638 gcc with the feature backported ("-fstack-protector"). 639 640 On an x86 "defconfig" build, this feature adds canary checks to 641 about 3% of all kernel functions, which increases kernel code size 642 by about 0.3%. 643 644config STACKPROTECTOR_STRONG 645 bool "Strong Stack Protector" 646 depends on STACKPROTECTOR 647 depends on $(cc-option,-fstack-protector-strong) 648 default y 649 help 650 Functions will have the stack-protector canary logic added in any 651 of the following conditions: 652 653 - local variable's address used as part of the right hand side of an 654 assignment or function argument 655 - local variable is an array (or union containing an array), 656 regardless of array type or length 657 - uses register local variables 658 659 This feature requires gcc version 4.9 or above, or a distribution 660 gcc with the feature backported ("-fstack-protector-strong"). 661 662 On an x86 "defconfig" build, this feature adds canary checks to 663 about 20% of all kernel functions, which increases the kernel code 664 size by about 2%. 665 666config ARCH_SUPPORTS_SHADOW_CALL_STACK 667 bool 668 help 669 An architecture should select this if it supports the compiler's 670 Shadow Call Stack and implements runtime support for shadow stack 671 switching. 672 673config SHADOW_CALL_STACK 674 bool "Shadow Call Stack" 675 depends on ARCH_SUPPORTS_SHADOW_CALL_STACK 676 depends on DYNAMIC_FTRACE_WITH_ARGS || DYNAMIC_FTRACE_WITH_REGS || !FUNCTION_GRAPH_TRACER 677 help 678 This option enables the compiler's Shadow Call Stack, which 679 uses a shadow stack to protect function return addresses from 680 being overwritten by an attacker. More information can be found 681 in the compiler's documentation: 682 683 - Clang: https://clang.llvm.org/docs/ShadowCallStack.html 684 - GCC: https://gcc.gnu.org/onlinedocs/gcc/Instrumentation-Options.html#Instrumentation-Options 685 686 Note that security guarantees in the kernel differ from the 687 ones documented for user space. The kernel must store addresses 688 of shadow stacks in memory, which means an attacker capable of 689 reading and writing arbitrary memory may be able to locate them 690 and hijack control flow by modifying the stacks. 691 692config DYNAMIC_SCS 693 bool 694 help 695 Set by the arch code if it relies on code patching to insert the 696 shadow call stack push and pop instructions rather than on the 697 compiler. 698 699config LTO 700 bool 701 help 702 Selected if the kernel will be built using the compiler's LTO feature. 703 704config LTO_CLANG 705 bool 706 select LTO 707 help 708 Selected if the kernel will be built using Clang's LTO feature. 709 710config ARCH_SUPPORTS_LTO_CLANG 711 bool 712 help 713 An architecture should select this option if it supports: 714 - compiling with Clang, 715 - compiling inline assembly with Clang's integrated assembler, 716 - and linking with LLD. 717 718config ARCH_SUPPORTS_LTO_CLANG_THIN 719 bool 720 help 721 An architecture should select this option if it can support Clang's 722 ThinLTO mode. 723 724config HAS_LTO_CLANG 725 def_bool y 726 depends on CC_IS_CLANG && LD_IS_LLD && AS_IS_LLVM 727 depends on $(success,$(NM) --help | head -n 1 | grep -qi llvm) 728 depends on $(success,$(AR) --help | head -n 1 | grep -qi llvm) 729 depends on ARCH_SUPPORTS_LTO_CLANG 730 depends on !FTRACE_MCOUNT_USE_RECORDMCOUNT 731 depends on !KASAN || KASAN_HW_TAGS 732 depends on !GCOV_KERNEL 733 help 734 The compiler and Kconfig options support building with Clang's 735 LTO. 736 737choice 738 prompt "Link Time Optimization (LTO)" 739 default LTO_NONE 740 help 741 This option enables Link Time Optimization (LTO), which allows the 742 compiler to optimize binaries globally. 743 744 If unsure, select LTO_NONE. Note that LTO is very resource-intensive 745 so it's disabled by default. 746 747config LTO_NONE 748 bool "None" 749 help 750 Build the kernel normally, without Link Time Optimization (LTO). 751 752config LTO_CLANG_FULL 753 bool "Clang Full LTO (EXPERIMENTAL)" 754 depends on HAS_LTO_CLANG 755 depends on !COMPILE_TEST 756 select LTO_CLANG 757 help 758 This option enables Clang's full Link Time Optimization (LTO), which 759 allows the compiler to optimize the kernel globally. If you enable 760 this option, the compiler generates LLVM bitcode instead of ELF 761 object files, and the actual compilation from bitcode happens at 762 the LTO link step, which may take several minutes depending on the 763 kernel configuration. More information can be found from LLVM's 764 documentation: 765 766 https://llvm.org/docs/LinkTimeOptimization.html 767 768 During link time, this option can use a large amount of RAM, and 769 may take much longer than the ThinLTO option. 770 771config LTO_CLANG_THIN 772 bool "Clang ThinLTO (EXPERIMENTAL)" 773 depends on HAS_LTO_CLANG && ARCH_SUPPORTS_LTO_CLANG_THIN 774 select LTO_CLANG 775 help 776 This option enables Clang's ThinLTO, which allows for parallel 777 optimization and faster incremental compiles compared to the 778 CONFIG_LTO_CLANG_FULL option. More information can be found 779 from Clang's documentation: 780 781 https://clang.llvm.org/docs/ThinLTO.html 782 783 If unsure, say Y. 784endchoice 785 786config ARCH_SUPPORTS_CFI_CLANG 787 bool 788 help 789 An architecture should select this option if it can support Clang's 790 Control-Flow Integrity (CFI) checking. 791 792config ARCH_USES_CFI_TRAPS 793 bool 794 795config CFI_CLANG 796 bool "Use Clang's Control Flow Integrity (CFI)" 797 depends on ARCH_SUPPORTS_CFI_CLANG 798 depends on $(cc-option,-fsanitize=kcfi) 799 help 800 This option enables Clang’s forward-edge Control Flow Integrity 801 (CFI) checking, where the compiler injects a runtime check to each 802 indirect function call to ensure the target is a valid function with 803 the correct static type. This restricts possible call targets and 804 makes it more difficult for an attacker to exploit bugs that allow 805 the modification of stored function pointers. More information can be 806 found from Clang's documentation: 807 808 https://clang.llvm.org/docs/ControlFlowIntegrity.html 809 810config CFI_PERMISSIVE 811 bool "Use CFI in permissive mode" 812 depends on CFI_CLANG 813 help 814 When selected, Control Flow Integrity (CFI) violations result in a 815 warning instead of a kernel panic. This option should only be used 816 for finding indirect call type mismatches during development. 817 818 If unsure, say N. 819 820config HAVE_ARCH_WITHIN_STACK_FRAMES 821 bool 822 help 823 An architecture should select this if it can walk the kernel stack 824 frames to determine if an object is part of either the arguments 825 or local variables (i.e. that it excludes saved return addresses, 826 and similar) by implementing an inline arch_within_stack_frames(), 827 which is used by CONFIG_HARDENED_USERCOPY. 828 829config HAVE_CONTEXT_TRACKING_USER 830 bool 831 help 832 Provide kernel/user boundaries probes necessary for subsystems 833 that need it, such as userspace RCU extended quiescent state. 834 Syscalls need to be wrapped inside user_exit()-user_enter(), either 835 optimized behind static key or through the slow path using TIF_NOHZ 836 flag. Exceptions handlers must be wrapped as well. Irqs are already 837 protected inside ct_irq_enter/ct_irq_exit() but preemption or signal 838 handling on irq exit still need to be protected. 839 840config HAVE_CONTEXT_TRACKING_USER_OFFSTACK 841 bool 842 help 843 Architecture neither relies on exception_enter()/exception_exit() 844 nor on schedule_user(). Also preempt_schedule_notrace() and 845 preempt_schedule_irq() can't be called in a preemptible section 846 while context tracking is CONTEXT_USER. This feature reflects a sane 847 entry implementation where the following requirements are met on 848 critical entry code, ie: before user_exit() or after user_enter(): 849 850 - Critical entry code isn't preemptible (or better yet: 851 not interruptible). 852 - No use of RCU read side critical sections, unless ct_nmi_enter() 853 got called. 854 - No use of instrumentation, unless instrumentation_begin() got 855 called. 856 857config HAVE_TIF_NOHZ 858 bool 859 help 860 Arch relies on TIF_NOHZ and syscall slow path to implement context 861 tracking calls to user_enter()/user_exit(). 862 863config HAVE_VIRT_CPU_ACCOUNTING 864 bool 865 866config HAVE_VIRT_CPU_ACCOUNTING_IDLE 867 bool 868 help 869 Architecture has its own way to account idle CPU time and therefore 870 doesn't implement vtime_account_idle(). 871 872config ARCH_HAS_SCALED_CPUTIME 873 bool 874 875config HAVE_VIRT_CPU_ACCOUNTING_GEN 876 bool 877 default y if 64BIT 878 help 879 With VIRT_CPU_ACCOUNTING_GEN, cputime_t becomes 64-bit. 880 Before enabling this option, arch code must be audited 881 to ensure there are no races in concurrent read/write of 882 cputime_t. For example, reading/writing 64-bit cputime_t on 883 some 32-bit arches may require multiple accesses, so proper 884 locking is needed to protect against concurrent accesses. 885 886config HAVE_IRQ_TIME_ACCOUNTING 887 bool 888 help 889 Archs need to ensure they use a high enough resolution clock to 890 support irq time accounting and then call enable_sched_clock_irqtime(). 891 892config HAVE_MOVE_PUD 893 bool 894 help 895 Architectures that select this are able to move page tables at the 896 PUD level. If there are only 3 page table levels, the move effectively 897 happens at the PGD level. 898 899config HAVE_MOVE_PMD 900 bool 901 help 902 Archs that select this are able to move page tables at the PMD level. 903 904config HAVE_ARCH_TRANSPARENT_HUGEPAGE 905 bool 906 907config HAVE_ARCH_TRANSPARENT_HUGEPAGE_PUD 908 bool 909 910config HAVE_ARCH_HUGE_VMAP 911 bool 912 913# 914# Archs that select this would be capable of PMD-sized vmaps (i.e., 915# arch_vmap_pmd_supported() returns true). The VM_ALLOW_HUGE_VMAP flag 916# must be used to enable allocations to use hugepages. 917# 918config HAVE_ARCH_HUGE_VMALLOC 919 depends on HAVE_ARCH_HUGE_VMAP 920 bool 921 922config ARCH_WANT_HUGE_PMD_SHARE 923 bool 924 925config HAVE_ARCH_SOFT_DIRTY 926 bool 927 928config HAVE_MOD_ARCH_SPECIFIC 929 bool 930 help 931 The arch uses struct mod_arch_specific to store data. Many arches 932 just need a simple module loader without arch specific data - those 933 should not enable this. 934 935config MODULES_USE_ELF_RELA 936 bool 937 help 938 Modules only use ELF RELA relocations. Modules with ELF REL 939 relocations will give an error. 940 941config MODULES_USE_ELF_REL 942 bool 943 help 944 Modules only use ELF REL relocations. Modules with ELF RELA 945 relocations will give an error. 946 947config ARCH_WANTS_MODULES_DATA_IN_VMALLOC 948 bool 949 help 950 For architectures like powerpc/32 which have constraints on module 951 allocation and need to allocate module data outside of module area. 952 953config HAVE_IRQ_EXIT_ON_IRQ_STACK 954 bool 955 help 956 Architecture doesn't only execute the irq handler on the irq stack 957 but also irq_exit(). This way we can process softirqs on this irq 958 stack instead of switching to a new one when we call __do_softirq() 959 in the end of an hardirq. 960 This spares a stack switch and improves cache usage on softirq 961 processing. 962 963config HAVE_SOFTIRQ_ON_OWN_STACK 964 bool 965 help 966 Architecture provides a function to run __do_softirq() on a 967 separate stack. 968 969config SOFTIRQ_ON_OWN_STACK 970 def_bool HAVE_SOFTIRQ_ON_OWN_STACK && !PREEMPT_RT 971 972config ALTERNATE_USER_ADDRESS_SPACE 973 bool 974 help 975 Architectures set this when the CPU uses separate address 976 spaces for kernel and user space pointers. In this case, the 977 access_ok() check on a __user pointer is skipped. 978 979config PGTABLE_LEVELS 980 int 981 default 2 982 983config ARCH_HAS_ELF_RANDOMIZE 984 bool 985 help 986 An architecture supports choosing randomized locations for 987 stack, mmap, brk, and ET_DYN. Defined functions: 988 - arch_mmap_rnd() 989 - arch_randomize_brk() 990 991config HAVE_ARCH_MMAP_RND_BITS 992 bool 993 help 994 An arch should select this symbol if it supports setting a variable 995 number of bits for use in establishing the base address for mmap 996 allocations, has MMU enabled and provides values for both: 997 - ARCH_MMAP_RND_BITS_MIN 998 - ARCH_MMAP_RND_BITS_MAX 999 1000config HAVE_EXIT_THREAD 1001 bool 1002 help 1003 An architecture implements exit_thread. 1004 1005config ARCH_MMAP_RND_BITS_MIN 1006 int 1007 1008config ARCH_MMAP_RND_BITS_MAX 1009 int 1010 1011config ARCH_MMAP_RND_BITS_DEFAULT 1012 int 1013 1014config ARCH_MMAP_RND_BITS 1015 int "Number of bits to use for ASLR of mmap base address" if EXPERT 1016 range ARCH_MMAP_RND_BITS_MIN ARCH_MMAP_RND_BITS_MAX 1017 default ARCH_MMAP_RND_BITS_DEFAULT if ARCH_MMAP_RND_BITS_DEFAULT 1018 default ARCH_MMAP_RND_BITS_MIN 1019 depends on HAVE_ARCH_MMAP_RND_BITS 1020 help 1021 This value can be used to select the number of bits to use to 1022 determine the random offset to the base address of vma regions 1023 resulting from mmap allocations. This value will be bounded 1024 by the architecture's minimum and maximum supported values. 1025 1026 This value can be changed after boot using the 1027 /proc/sys/vm/mmap_rnd_bits tunable 1028 1029config HAVE_ARCH_MMAP_RND_COMPAT_BITS 1030 bool 1031 help 1032 An arch should select this symbol if it supports running applications 1033 in compatibility mode, supports setting a variable number of bits for 1034 use in establishing the base address for mmap allocations, has MMU 1035 enabled and provides values for both: 1036 - ARCH_MMAP_RND_COMPAT_BITS_MIN 1037 - ARCH_MMAP_RND_COMPAT_BITS_MAX 1038 1039config ARCH_MMAP_RND_COMPAT_BITS_MIN 1040 int 1041 1042config ARCH_MMAP_RND_COMPAT_BITS_MAX 1043 int 1044 1045config ARCH_MMAP_RND_COMPAT_BITS_DEFAULT 1046 int 1047 1048config ARCH_MMAP_RND_COMPAT_BITS 1049 int "Number of bits to use for ASLR of mmap base address for compatible applications" if EXPERT 1050 range ARCH_MMAP_RND_COMPAT_BITS_MIN ARCH_MMAP_RND_COMPAT_BITS_MAX 1051 default ARCH_MMAP_RND_COMPAT_BITS_DEFAULT if ARCH_MMAP_RND_COMPAT_BITS_DEFAULT 1052 default ARCH_MMAP_RND_COMPAT_BITS_MIN 1053 depends on HAVE_ARCH_MMAP_RND_COMPAT_BITS 1054 help 1055 This value can be used to select the number of bits to use to 1056 determine the random offset to the base address of vma regions 1057 resulting from mmap allocations for compatible applications This 1058 value will be bounded by the architecture's minimum and maximum 1059 supported values. 1060 1061 This value can be changed after boot using the 1062 /proc/sys/vm/mmap_rnd_compat_bits tunable 1063 1064config HAVE_ARCH_COMPAT_MMAP_BASES 1065 bool 1066 help 1067 This allows 64bit applications to invoke 32-bit mmap() syscall 1068 and vice-versa 32-bit applications to call 64-bit mmap(). 1069 Required for applications doing different bitness syscalls. 1070 1071config PAGE_SIZE_LESS_THAN_64KB 1072 def_bool y 1073 depends on !ARM64_64K_PAGES 1074 depends on !IA64_PAGE_SIZE_64KB 1075 depends on !PAGE_SIZE_64KB 1076 depends on !PARISC_PAGE_SIZE_64KB 1077 depends on PAGE_SIZE_LESS_THAN_256KB 1078 1079config PAGE_SIZE_LESS_THAN_256KB 1080 def_bool y 1081 depends on !PAGE_SIZE_256KB 1082 1083# This allows to use a set of generic functions to determine mmap base 1084# address by giving priority to top-down scheme only if the process 1085# is not in legacy mode (compat task, unlimited stack size or 1086# sysctl_legacy_va_layout). 1087# Architecture that selects this option can provide its own version of: 1088# - STACK_RND_MASK 1089config ARCH_WANT_DEFAULT_TOPDOWN_MMAP_LAYOUT 1090 bool 1091 depends on MMU 1092 select ARCH_HAS_ELF_RANDOMIZE 1093 1094config HAVE_OBJTOOL 1095 bool 1096 1097config HAVE_JUMP_LABEL_HACK 1098 bool 1099 1100config HAVE_NOINSTR_HACK 1101 bool 1102 1103config HAVE_NOINSTR_VALIDATION 1104 bool 1105 1106config HAVE_UACCESS_VALIDATION 1107 bool 1108 select OBJTOOL 1109 1110config HAVE_STACK_VALIDATION 1111 bool 1112 help 1113 Architecture supports objtool compile-time frame pointer rule 1114 validation. 1115 1116config HAVE_RELIABLE_STACKTRACE 1117 bool 1118 help 1119 Architecture has either save_stack_trace_tsk_reliable() or 1120 arch_stack_walk_reliable() function which only returns a stack trace 1121 if it can guarantee the trace is reliable. 1122 1123config HAVE_ARCH_HASH 1124 bool 1125 default n 1126 help 1127 If this is set, the architecture provides an <asm/hash.h> 1128 file which provides platform-specific implementations of some 1129 functions in <linux/hash.h> or fs/namei.c. 1130 1131config HAVE_ARCH_NVRAM_OPS 1132 bool 1133 1134config ISA_BUS_API 1135 def_bool ISA 1136 1137# 1138# ABI hall of shame 1139# 1140config CLONE_BACKWARDS 1141 bool 1142 help 1143 Architecture has tls passed as the 4th argument of clone(2), 1144 not the 5th one. 1145 1146config CLONE_BACKWARDS2 1147 bool 1148 help 1149 Architecture has the first two arguments of clone(2) swapped. 1150 1151config CLONE_BACKWARDS3 1152 bool 1153 help 1154 Architecture has tls passed as the 3rd argument of clone(2), 1155 not the 5th one. 1156 1157config ODD_RT_SIGACTION 1158 bool 1159 help 1160 Architecture has unusual rt_sigaction(2) arguments 1161 1162config OLD_SIGSUSPEND 1163 bool 1164 help 1165 Architecture has old sigsuspend(2) syscall, of one-argument variety 1166 1167config OLD_SIGSUSPEND3 1168 bool 1169 help 1170 Even weirder antique ABI - three-argument sigsuspend(2) 1171 1172config OLD_SIGACTION 1173 bool 1174 help 1175 Architecture has old sigaction(2) syscall. Nope, not the same 1176 as OLD_SIGSUSPEND | OLD_SIGSUSPEND3 - alpha has sigsuspend(2), 1177 but fairly different variant of sigaction(2), thanks to OSF/1 1178 compatibility... 1179 1180config COMPAT_OLD_SIGACTION 1181 bool 1182 1183config COMPAT_32BIT_TIME 1184 bool "Provide system calls for 32-bit time_t" 1185 default !64BIT || COMPAT 1186 help 1187 This enables 32 bit time_t support in addition to 64 bit time_t support. 1188 This is relevant on all 32-bit architectures, and 64-bit architectures 1189 as part of compat syscall handling. 1190 1191config ARCH_NO_PREEMPT 1192 bool 1193 1194config ARCH_EPHEMERAL_INODES 1195 def_bool n 1196 help 1197 An arch should select this symbol if it doesn't keep track of inode 1198 instances on its own, but instead relies on something else (e.g. the 1199 host kernel for an UML kernel). 1200 1201config ARCH_SUPPORTS_RT 1202 bool 1203 1204config CPU_NO_EFFICIENT_FFS 1205 def_bool n 1206 1207config HAVE_ARCH_VMAP_STACK 1208 def_bool n 1209 help 1210 An arch should select this symbol if it can support kernel stacks 1211 in vmalloc space. This means: 1212 1213 - vmalloc space must be large enough to hold many kernel stacks. 1214 This may rule out many 32-bit architectures. 1215 1216 - Stacks in vmalloc space need to work reliably. For example, if 1217 vmap page tables are created on demand, either this mechanism 1218 needs to work while the stack points to a virtual address with 1219 unpopulated page tables or arch code (switch_to() and switch_mm(), 1220 most likely) needs to ensure that the stack's page table entries 1221 are populated before running on a possibly unpopulated stack. 1222 1223 - If the stack overflows into a guard page, something reasonable 1224 should happen. The definition of "reasonable" is flexible, but 1225 instantly rebooting without logging anything would be unfriendly. 1226 1227config VMAP_STACK 1228 default y 1229 bool "Use a virtually-mapped stack" 1230 depends on HAVE_ARCH_VMAP_STACK 1231 depends on !KASAN || KASAN_HW_TAGS || KASAN_VMALLOC 1232 help 1233 Enable this if you want the use virtually-mapped kernel stacks 1234 with guard pages. This causes kernel stack overflows to be 1235 caught immediately rather than causing difficult-to-diagnose 1236 corruption. 1237 1238 To use this with software KASAN modes, the architecture must support 1239 backing virtual mappings with real shadow memory, and KASAN_VMALLOC 1240 must be enabled. 1241 1242config HAVE_ARCH_RANDOMIZE_KSTACK_OFFSET 1243 def_bool n 1244 help 1245 An arch should select this symbol if it can support kernel stack 1246 offset randomization with calls to add_random_kstack_offset() 1247 during syscall entry and choose_random_kstack_offset() during 1248 syscall exit. Careful removal of -fstack-protector-strong and 1249 -fstack-protector should also be applied to the entry code and 1250 closely examined, as the artificial stack bump looks like an array 1251 to the compiler, so it will attempt to add canary checks regardless 1252 of the static branch state. 1253 1254config RANDOMIZE_KSTACK_OFFSET 1255 bool "Support for randomizing kernel stack offset on syscall entry" if EXPERT 1256 default y 1257 depends on HAVE_ARCH_RANDOMIZE_KSTACK_OFFSET 1258 depends on INIT_STACK_NONE || !CC_IS_CLANG || CLANG_VERSION >= 140000 1259 help 1260 The kernel stack offset can be randomized (after pt_regs) by 1261 roughly 5 bits of entropy, frustrating memory corruption 1262 attacks that depend on stack address determinism or 1263 cross-syscall address exposures. 1264 1265 The feature is controlled via the "randomize_kstack_offset=on/off" 1266 kernel boot param, and if turned off has zero overhead due to its use 1267 of static branches (see JUMP_LABEL). 1268 1269 If unsure, say Y. 1270 1271config RANDOMIZE_KSTACK_OFFSET_DEFAULT 1272 bool "Default state of kernel stack offset randomization" 1273 depends on RANDOMIZE_KSTACK_OFFSET 1274 help 1275 Kernel stack offset randomization is controlled by kernel boot param 1276 "randomize_kstack_offset=on/off", and this config chooses the default 1277 boot state. 1278 1279config ARCH_OPTIONAL_KERNEL_RWX 1280 def_bool n 1281 1282config ARCH_OPTIONAL_KERNEL_RWX_DEFAULT 1283 def_bool n 1284 1285config ARCH_HAS_STRICT_KERNEL_RWX 1286 def_bool n 1287 1288config STRICT_KERNEL_RWX 1289 bool "Make kernel text and rodata read-only" if ARCH_OPTIONAL_KERNEL_RWX 1290 depends on ARCH_HAS_STRICT_KERNEL_RWX 1291 default !ARCH_OPTIONAL_KERNEL_RWX || ARCH_OPTIONAL_KERNEL_RWX_DEFAULT 1292 help 1293 If this is set, kernel text and rodata memory will be made read-only, 1294 and non-text memory will be made non-executable. This provides 1295 protection against certain security exploits (e.g. executing the heap 1296 or modifying text) 1297 1298 These features are considered standard security practice these days. 1299 You should say Y here in almost all cases. 1300 1301config ARCH_HAS_STRICT_MODULE_RWX 1302 def_bool n 1303 1304config STRICT_MODULE_RWX 1305 bool "Set loadable kernel module data as NX and text as RO" if ARCH_OPTIONAL_KERNEL_RWX 1306 depends on ARCH_HAS_STRICT_MODULE_RWX && MODULES 1307 default !ARCH_OPTIONAL_KERNEL_RWX || ARCH_OPTIONAL_KERNEL_RWX_DEFAULT 1308 help 1309 If this is set, module text and rodata memory will be made read-only, 1310 and non-text memory will be made non-executable. This provides 1311 protection against certain security exploits (e.g. writing to text) 1312 1313# select if the architecture provides an asm/dma-direct.h header 1314config ARCH_HAS_PHYS_TO_DMA 1315 bool 1316 1317config HAVE_ARCH_COMPILER_H 1318 bool 1319 help 1320 An architecture can select this if it provides an 1321 asm/compiler.h header that should be included after 1322 linux/compiler-*.h in order to override macro definitions that those 1323 headers generally provide. 1324 1325config HAVE_ARCH_PREL32_RELOCATIONS 1326 bool 1327 help 1328 May be selected by an architecture if it supports place-relative 1329 32-bit relocations, both in the toolchain and in the module loader, 1330 in which case relative references can be used in special sections 1331 for PCI fixup, initcalls etc which are only half the size on 64 bit 1332 architectures, and don't require runtime relocation on relocatable 1333 kernels. 1334 1335config ARCH_USE_MEMREMAP_PROT 1336 bool 1337 1338config LOCK_EVENT_COUNTS 1339 bool "Locking event counts collection" 1340 depends on DEBUG_FS 1341 help 1342 Enable light-weight counting of various locking related events 1343 in the system with minimal performance impact. This reduces 1344 the chance of application behavior change because of timing 1345 differences. The counts are reported via debugfs. 1346 1347# Select if the architecture has support for applying RELR relocations. 1348config ARCH_HAS_RELR 1349 bool 1350 1351config RELR 1352 bool "Use RELR relocation packing" 1353 depends on ARCH_HAS_RELR && TOOLS_SUPPORT_RELR 1354 default y 1355 help 1356 Store the kernel's dynamic relocations in the RELR relocation packing 1357 format. Requires a compatible linker (LLD supports this feature), as 1358 well as compatible NM and OBJCOPY utilities (llvm-nm and llvm-objcopy 1359 are compatible). 1360 1361config ARCH_HAS_MEM_ENCRYPT 1362 bool 1363 1364config ARCH_HAS_CC_PLATFORM 1365 bool 1366 1367config HAVE_SPARSE_SYSCALL_NR 1368 bool 1369 help 1370 An architecture should select this if its syscall numbering is sparse 1371 to save space. For example, MIPS architecture has a syscall array with 1372 entries at 4000, 5000 and 6000 locations. This option turns on syscall 1373 related optimizations for a given architecture. 1374 1375config ARCH_HAS_VDSO_DATA 1376 bool 1377 1378config HAVE_STATIC_CALL 1379 bool 1380 1381config HAVE_STATIC_CALL_INLINE 1382 bool 1383 depends on HAVE_STATIC_CALL 1384 select OBJTOOL 1385 1386config HAVE_PREEMPT_DYNAMIC 1387 bool 1388 1389config HAVE_PREEMPT_DYNAMIC_CALL 1390 bool 1391 depends on HAVE_STATIC_CALL 1392 select HAVE_PREEMPT_DYNAMIC 1393 help 1394 An architecture should select this if it can handle the preemption 1395 model being selected at boot time using static calls. 1396 1397 Where an architecture selects HAVE_STATIC_CALL_INLINE, any call to a 1398 preemption function will be patched directly. 1399 1400 Where an architecture does not select HAVE_STATIC_CALL_INLINE, any 1401 call to a preemption function will go through a trampoline, and the 1402 trampoline will be patched. 1403 1404 It is strongly advised to support inline static call to avoid any 1405 overhead. 1406 1407config HAVE_PREEMPT_DYNAMIC_KEY 1408 bool 1409 depends on HAVE_ARCH_JUMP_LABEL 1410 select HAVE_PREEMPT_DYNAMIC 1411 help 1412 An architecture should select this if it can handle the preemption 1413 model being selected at boot time using static keys. 1414 1415 Each preemption function will be given an early return based on a 1416 static key. This should have slightly lower overhead than non-inline 1417 static calls, as this effectively inlines each trampoline into the 1418 start of its callee. This may avoid redundant work, and may 1419 integrate better with CFI schemes. 1420 1421 This will have greater overhead than using inline static calls as 1422 the call to the preemption function cannot be entirely elided. 1423 1424config ARCH_WANT_LD_ORPHAN_WARN 1425 bool 1426 help 1427 An arch should select this symbol once all linker sections are explicitly 1428 included, size-asserted, or discarded in the linker scripts. This is 1429 important because we never want expected sections to be placed heuristically 1430 by the linker, since the locations of such sections can change between linker 1431 versions. 1432 1433config HAVE_ARCH_PFN_VALID 1434 bool 1435 1436config ARCH_SUPPORTS_DEBUG_PAGEALLOC 1437 bool 1438 1439config ARCH_SUPPORTS_PAGE_TABLE_CHECK 1440 bool 1441 1442config ARCH_SPLIT_ARG64 1443 bool 1444 help 1445 If a 32-bit architecture requires 64-bit arguments to be split into 1446 pairs of 32-bit arguments, select this option. 1447 1448config ARCH_HAS_ELFCORE_COMPAT 1449 bool 1450 1451config ARCH_HAS_PARANOID_L1D_FLUSH 1452 bool 1453 1454config ARCH_HAVE_TRACE_MMIO_ACCESS 1455 bool 1456 1457config DYNAMIC_SIGFRAME 1458 bool 1459 1460# Select, if arch has a named attribute group bound to NUMA device nodes. 1461config HAVE_ARCH_NODE_DEV_GROUP 1462 bool 1463 1464config ARCH_HAS_NONLEAF_PMD_YOUNG 1465 bool 1466 help 1467 Architectures that select this option are capable of setting the 1468 accessed bit in non-leaf PMD entries when using them as part of linear 1469 address translations. Page table walkers that clear the accessed bit 1470 may use this capability to reduce their search space. 1471 1472source "kernel/gcov/Kconfig" 1473 1474source "scripts/gcc-plugins/Kconfig" 1475 1476config FUNCTION_ALIGNMENT_4B 1477 bool 1478 1479config FUNCTION_ALIGNMENT_8B 1480 bool 1481 1482config FUNCTION_ALIGNMENT_16B 1483 bool 1484 1485config FUNCTION_ALIGNMENT_32B 1486 bool 1487 1488config FUNCTION_ALIGNMENT_64B 1489 bool 1490 1491config FUNCTION_ALIGNMENT 1492 int 1493 default 64 if FUNCTION_ALIGNMENT_64B 1494 default 32 if FUNCTION_ALIGNMENT_32B 1495 default 16 if FUNCTION_ALIGNMENT_16B 1496 default 8 if FUNCTION_ALIGNMENT_8B 1497 default 4 if FUNCTION_ALIGNMENT_4B 1498 default 0 1499 1500endmenu 1501