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 37# Selected by HOTPLUG_CORE_SYNC_DEAD or HOTPLUG_CORE_SYNC_FULL 38config HOTPLUG_CORE_SYNC 39 bool 40 41# Basic CPU dead synchronization selected by architecture 42config HOTPLUG_CORE_SYNC_DEAD 43 bool 44 select HOTPLUG_CORE_SYNC 45 46# Full CPU synchronization with alive state selected by architecture 47config HOTPLUG_CORE_SYNC_FULL 48 bool 49 select HOTPLUG_CORE_SYNC_DEAD if HOTPLUG_CPU 50 select HOTPLUG_CORE_SYNC 51 52config HOTPLUG_SPLIT_STARTUP 53 bool 54 select HOTPLUG_CORE_SYNC_FULL 55 56config HOTPLUG_PARALLEL 57 bool 58 select HOTPLUG_SPLIT_STARTUP 59 60config GENERIC_ENTRY 61 bool 62 63config KPROBES 64 bool "Kprobes" 65 depends on MODULES 66 depends on HAVE_KPROBES 67 select KALLSYMS 68 select TASKS_RCU if PREEMPTION 69 help 70 Kprobes allows you to trap at almost any kernel address and 71 execute a callback function. register_kprobe() establishes 72 a probepoint and specifies the callback. Kprobes is useful 73 for kernel debugging, non-intrusive instrumentation and testing. 74 If in doubt, say "N". 75 76config JUMP_LABEL 77 bool "Optimize very unlikely/likely branches" 78 depends on HAVE_ARCH_JUMP_LABEL 79 select OBJTOOL if HAVE_JUMP_LABEL_HACK 80 help 81 This option enables a transparent branch optimization that 82 makes certain almost-always-true or almost-always-false branch 83 conditions even cheaper to execute within the kernel. 84 85 Certain performance-sensitive kernel code, such as trace points, 86 scheduler functionality, networking code and KVM have such 87 branches and include support for this optimization technique. 88 89 If it is detected that the compiler has support for "asm goto", 90 the kernel will compile such branches with just a nop 91 instruction. When the condition flag is toggled to true, the 92 nop will be converted to a jump instruction to execute the 93 conditional block of instructions. 94 95 This technique lowers overhead and stress on the branch prediction 96 of the processor and generally makes the kernel faster. The update 97 of the condition is slower, but those are always very rare. 98 99 ( On 32-bit x86, the necessary options added to the compiler 100 flags may increase the size of the kernel slightly. ) 101 102config STATIC_KEYS_SELFTEST 103 bool "Static key selftest" 104 depends on JUMP_LABEL 105 help 106 Boot time self-test of the branch patching code. 107 108config STATIC_CALL_SELFTEST 109 bool "Static call selftest" 110 depends on HAVE_STATIC_CALL 111 help 112 Boot time self-test of the call patching code. 113 114config OPTPROBES 115 def_bool y 116 depends on KPROBES && HAVE_OPTPROBES 117 select TASKS_RCU if PREEMPTION 118 119config KPROBES_ON_FTRACE 120 def_bool y 121 depends on KPROBES && HAVE_KPROBES_ON_FTRACE 122 depends on DYNAMIC_FTRACE_WITH_REGS 123 help 124 If function tracer is enabled and the arch supports full 125 passing of pt_regs to function tracing, then kprobes can 126 optimize on top of function tracing. 127 128config UPROBES 129 def_bool n 130 depends on ARCH_SUPPORTS_UPROBES 131 help 132 Uprobes is the user-space counterpart to kprobes: they 133 enable instrumentation applications (such as 'perf probe') 134 to establish unintrusive probes in user-space binaries and 135 libraries, by executing handler functions when the probes 136 are hit by user-space applications. 137 138 ( These probes come in the form of single-byte breakpoints, 139 managed by the kernel and kept transparent to the probed 140 application. ) 141 142config HAVE_64BIT_ALIGNED_ACCESS 143 def_bool 64BIT && !HAVE_EFFICIENT_UNALIGNED_ACCESS 144 help 145 Some architectures require 64 bit accesses to be 64 bit 146 aligned, which also requires structs containing 64 bit values 147 to be 64 bit aligned too. This includes some 32 bit 148 architectures which can do 64 bit accesses, as well as 64 bit 149 architectures without unaligned access. 150 151 This symbol should be selected by an architecture if 64 bit 152 accesses are required to be 64 bit aligned in this way even 153 though it is not a 64 bit architecture. 154 155 See Documentation/core-api/unaligned-memory-access.rst for 156 more information on the topic of unaligned memory accesses. 157 158config HAVE_EFFICIENT_UNALIGNED_ACCESS 159 bool 160 help 161 Some architectures are unable to perform unaligned accesses 162 without the use of get_unaligned/put_unaligned. Others are 163 unable to perform such accesses efficiently (e.g. trap on 164 unaligned access and require fixing it up in the exception 165 handler.) 166 167 This symbol should be selected by an architecture if it can 168 perform unaligned accesses efficiently to allow different 169 code paths to be selected for these cases. Some network 170 drivers, for example, could opt to not fix up alignment 171 problems with received packets if doing so would not help 172 much. 173 174 See Documentation/core-api/unaligned-memory-access.rst for more 175 information on the topic of unaligned memory accesses. 176 177config ARCH_USE_BUILTIN_BSWAP 178 bool 179 help 180 Modern versions of GCC (since 4.4) have builtin functions 181 for handling byte-swapping. Using these, instead of the old 182 inline assembler that the architecture code provides in the 183 __arch_bswapXX() macros, allows the compiler to see what's 184 happening and offers more opportunity for optimisation. In 185 particular, the compiler will be able to combine the byteswap 186 with a nearby load or store and use load-and-swap or 187 store-and-swap instructions if the architecture has them. It 188 should almost *never* result in code which is worse than the 189 hand-coded assembler in <asm/swab.h>. But just in case it 190 does, the use of the builtins is optional. 191 192 Any architecture with load-and-swap or store-and-swap 193 instructions should set this. And it shouldn't hurt to set it 194 on architectures that don't have such instructions. 195 196config KRETPROBES 197 def_bool y 198 depends on KPROBES && (HAVE_KRETPROBES || HAVE_RETHOOK) 199 200config KRETPROBE_ON_RETHOOK 201 def_bool y 202 depends on HAVE_RETHOOK 203 depends on KRETPROBES 204 select RETHOOK 205 206config USER_RETURN_NOTIFIER 207 bool 208 depends on HAVE_USER_RETURN_NOTIFIER 209 help 210 Provide a kernel-internal notification when a cpu is about to 211 switch to user mode. 212 213config HAVE_IOREMAP_PROT 214 bool 215 216config HAVE_KPROBES 217 bool 218 219config HAVE_KRETPROBES 220 bool 221 222config HAVE_OPTPROBES 223 bool 224 225config HAVE_KPROBES_ON_FTRACE 226 bool 227 228config ARCH_CORRECT_STACKTRACE_ON_KRETPROBE 229 bool 230 help 231 Since kretprobes modifies return address on the stack, the 232 stacktrace may see the kretprobe trampoline address instead 233 of correct one. If the architecture stacktrace code and 234 unwinder can adjust such entries, select this configuration. 235 236config HAVE_FUNCTION_ERROR_INJECTION 237 bool 238 239config HAVE_NMI 240 bool 241 242config HAVE_FUNCTION_DESCRIPTORS 243 bool 244 245config TRACE_IRQFLAGS_SUPPORT 246 bool 247 248config TRACE_IRQFLAGS_NMI_SUPPORT 249 bool 250 251# 252# An arch should select this if it provides all these things: 253# 254# task_pt_regs() in asm/processor.h or asm/ptrace.h 255# arch_has_single_step() if there is hardware single-step support 256# arch_has_block_step() if there is hardware block-step support 257# asm/syscall.h supplying asm-generic/syscall.h interface 258# linux/regset.h user_regset interfaces 259# CORE_DUMP_USE_REGSET #define'd in linux/elf.h 260# TIF_SYSCALL_TRACE calls ptrace_report_syscall_{entry,exit} 261# TIF_NOTIFY_RESUME calls resume_user_mode_work() 262# 263config HAVE_ARCH_TRACEHOOK 264 bool 265 266config HAVE_DMA_CONTIGUOUS 267 bool 268 269config GENERIC_SMP_IDLE_THREAD 270 bool 271 272config GENERIC_IDLE_POLL_SETUP 273 bool 274 275config ARCH_HAS_FORTIFY_SOURCE 276 bool 277 help 278 An architecture should select this when it can successfully 279 build and run with CONFIG_FORTIFY_SOURCE. 280 281# 282# Select if the arch provides a historic keepinit alias for the retain_initrd 283# command line option 284# 285config ARCH_HAS_KEEPINITRD 286 bool 287 288# Select if arch has all set_memory_ro/rw/x/nx() functions in asm/cacheflush.h 289config ARCH_HAS_SET_MEMORY 290 bool 291 292# Select if arch has all set_direct_map_invalid/default() functions 293config ARCH_HAS_SET_DIRECT_MAP 294 bool 295 296# 297# Select if the architecture provides the arch_dma_set_uncached symbol to 298# either provide an uncached segment alias for a DMA allocation, or 299# to remap the page tables in place. 300# 301config ARCH_HAS_DMA_SET_UNCACHED 302 bool 303 304# 305# Select if the architectures provides the arch_dma_clear_uncached symbol 306# to undo an in-place page table remap for uncached access. 307# 308config ARCH_HAS_DMA_CLEAR_UNCACHED 309 bool 310 311config ARCH_HAS_CPU_FINALIZE_INIT 312 bool 313 314# Select if arch init_task must go in the __init_task_data section 315config ARCH_TASK_STRUCT_ON_STACK 316 bool 317 318# Select if arch has its private alloc_task_struct() function 319config ARCH_TASK_STRUCT_ALLOCATOR 320 bool 321 322config HAVE_ARCH_THREAD_STRUCT_WHITELIST 323 bool 324 depends on !ARCH_TASK_STRUCT_ALLOCATOR 325 help 326 An architecture should select this to provide hardened usercopy 327 knowledge about what region of the thread_struct should be 328 whitelisted for copying to userspace. Normally this is only the 329 FPU registers. Specifically, arch_thread_struct_whitelist() 330 should be implemented. Without this, the entire thread_struct 331 field in task_struct will be left whitelisted. 332 333# Select if arch has its private alloc_thread_stack() function 334config ARCH_THREAD_STACK_ALLOCATOR 335 bool 336 337# Select if arch wants to size task_struct dynamically via arch_task_struct_size: 338config ARCH_WANTS_DYNAMIC_TASK_STRUCT 339 bool 340 341config ARCH_WANTS_NO_INSTR 342 bool 343 help 344 An architecture should select this if the noinstr macro is being used on 345 functions to denote that the toolchain should avoid instrumenting such 346 functions and is required for correctness. 347 348config ARCH_32BIT_OFF_T 349 bool 350 depends on !64BIT 351 help 352 All new 32-bit architectures should have 64-bit off_t type on 353 userspace side which corresponds to the loff_t kernel type. This 354 is the requirement for modern ABIs. Some existing architectures 355 still support 32-bit off_t. This option is enabled for all such 356 architectures explicitly. 357 358# Selected by 64 bit architectures which have a 32 bit f_tinode in struct ustat 359config ARCH_32BIT_USTAT_F_TINODE 360 bool 361 362config HAVE_ASM_MODVERSIONS 363 bool 364 help 365 This symbol should be selected by an architecture if it provides 366 <asm/asm-prototypes.h> to support the module versioning for symbols 367 exported from assembly code. 368 369config HAVE_REGS_AND_STACK_ACCESS_API 370 bool 371 help 372 This symbol should be selected by an architecture if it supports 373 the API needed to access registers and stack entries from pt_regs, 374 declared in asm/ptrace.h 375 For example the kprobes-based event tracer needs this API. 376 377config HAVE_RSEQ 378 bool 379 depends on HAVE_REGS_AND_STACK_ACCESS_API 380 help 381 This symbol should be selected by an architecture if it 382 supports an implementation of restartable sequences. 383 384config HAVE_RUST 385 bool 386 help 387 This symbol should be selected by an architecture if it 388 supports Rust. 389 390config HAVE_FUNCTION_ARG_ACCESS_API 391 bool 392 help 393 This symbol should be selected by an architecture if it supports 394 the API needed to access function arguments from pt_regs, 395 declared in asm/ptrace.h 396 397config HAVE_HW_BREAKPOINT 398 bool 399 depends on PERF_EVENTS 400 401config HAVE_MIXED_BREAKPOINTS_REGS 402 bool 403 depends on HAVE_HW_BREAKPOINT 404 help 405 Depending on the arch implementation of hardware breakpoints, 406 some of them have separate registers for data and instruction 407 breakpoints addresses, others have mixed registers to store 408 them but define the access type in a control register. 409 Select this option if your arch implements breakpoints under the 410 latter fashion. 411 412config HAVE_USER_RETURN_NOTIFIER 413 bool 414 415config HAVE_PERF_EVENTS_NMI 416 bool 417 help 418 System hardware can generate an NMI using the perf event 419 subsystem. Also has support for calculating CPU cycle events 420 to determine how many clock cycles in a given period. 421 422config HAVE_HARDLOCKUP_DETECTOR_PERF 423 bool 424 depends on HAVE_PERF_EVENTS_NMI 425 help 426 The arch chooses to use the generic perf-NMI-based hardlockup 427 detector. Must define HAVE_PERF_EVENTS_NMI. 428 429config HAVE_HARDLOCKUP_DETECTOR_ARCH 430 bool 431 help 432 The arch provides its own hardlockup detector implementation instead 433 of the generic ones. 434 435 It uses the same command line parameters, and sysctl interface, 436 as the generic hardlockup detectors. 437 438config HAVE_PERF_REGS 439 bool 440 help 441 Support selective register dumps for perf events. This includes 442 bit-mapping of each registers and a unique architecture id. 443 444config HAVE_PERF_USER_STACK_DUMP 445 bool 446 help 447 Support user stack dumps for perf event samples. This needs 448 access to the user stack pointer which is not unified across 449 architectures. 450 451config HAVE_ARCH_JUMP_LABEL 452 bool 453 454config HAVE_ARCH_JUMP_LABEL_RELATIVE 455 bool 456 457config MMU_GATHER_TABLE_FREE 458 bool 459 460config MMU_GATHER_RCU_TABLE_FREE 461 bool 462 select MMU_GATHER_TABLE_FREE 463 464config MMU_GATHER_PAGE_SIZE 465 bool 466 467config MMU_GATHER_NO_RANGE 468 bool 469 select MMU_GATHER_MERGE_VMAS 470 471config MMU_GATHER_NO_FLUSH_CACHE 472 bool 473 474config MMU_GATHER_MERGE_VMAS 475 bool 476 477config MMU_GATHER_NO_GATHER 478 bool 479 depends on MMU_GATHER_TABLE_FREE 480 481config ARCH_WANT_IRQS_OFF_ACTIVATE_MM 482 bool 483 help 484 Temporary select until all architectures can be converted to have 485 irqs disabled over activate_mm. Architectures that do IPI based TLB 486 shootdowns should enable this. 487 488# Use normal mm refcounting for MMU_LAZY_TLB kernel thread references. 489# MMU_LAZY_TLB_REFCOUNT=n can improve the scalability of context switching 490# to/from kernel threads when the same mm is running on a lot of CPUs (a large 491# multi-threaded application), by reducing contention on the mm refcount. 492# 493# This can be disabled if the architecture ensures no CPUs are using an mm as a 494# "lazy tlb" beyond its final refcount (i.e., by the time __mmdrop frees the mm 495# or its kernel page tables). This could be arranged by arch_exit_mmap(), or 496# final exit(2) TLB flush, for example. 497# 498# To implement this, an arch *must*: 499# Ensure the _lazy_tlb variants of mmgrab/mmdrop are used when manipulating 500# the lazy tlb reference of a kthread's ->active_mm (non-arch code has been 501# converted already). 502config MMU_LAZY_TLB_REFCOUNT 503 def_bool y 504 depends on !MMU_LAZY_TLB_SHOOTDOWN 505 506# This option allows MMU_LAZY_TLB_REFCOUNT=n. It ensures no CPUs are using an 507# mm as a lazy tlb beyond its last reference count, by shooting down these 508# users before the mm is deallocated. __mmdrop() first IPIs all CPUs that may 509# be using the mm as a lazy tlb, so that they may switch themselves to using 510# init_mm for their active mm. mm_cpumask(mm) is used to determine which CPUs 511# may be using mm as a lazy tlb mm. 512# 513# To implement this, an arch *must*: 514# - At the time of the final mmdrop of the mm, ensure mm_cpumask(mm) contains 515# at least all possible CPUs in which the mm is lazy. 516# - It must meet the requirements for MMU_LAZY_TLB_REFCOUNT=n (see above). 517config MMU_LAZY_TLB_SHOOTDOWN 518 bool 519 520config ARCH_HAVE_NMI_SAFE_CMPXCHG 521 bool 522 523config ARCH_HAS_NMI_SAFE_THIS_CPU_OPS 524 bool 525 526config HAVE_ALIGNED_STRUCT_PAGE 527 bool 528 help 529 This makes sure that struct pages are double word aligned and that 530 e.g. the SLUB allocator can perform double word atomic operations 531 on a struct page for better performance. However selecting this 532 might increase the size of a struct page by a word. 533 534config HAVE_CMPXCHG_LOCAL 535 bool 536 537config HAVE_CMPXCHG_DOUBLE 538 bool 539 540config ARCH_WEAK_RELEASE_ACQUIRE 541 bool 542 543config ARCH_WANT_IPC_PARSE_VERSION 544 bool 545 546config ARCH_WANT_COMPAT_IPC_PARSE_VERSION 547 bool 548 549config ARCH_WANT_OLD_COMPAT_IPC 550 select ARCH_WANT_COMPAT_IPC_PARSE_VERSION 551 bool 552 553config HAVE_ARCH_SECCOMP 554 bool 555 help 556 An arch should select this symbol to support seccomp mode 1 (the fixed 557 syscall policy), and must provide an overrides for __NR_seccomp_sigreturn, 558 and compat syscalls if the asm-generic/seccomp.h defaults need adjustment: 559 - __NR_seccomp_read_32 560 - __NR_seccomp_write_32 561 - __NR_seccomp_exit_32 562 - __NR_seccomp_sigreturn_32 563 564config HAVE_ARCH_SECCOMP_FILTER 565 bool 566 select HAVE_ARCH_SECCOMP 567 help 568 An arch should select this symbol if it provides all of these things: 569 - all the requirements for HAVE_ARCH_SECCOMP 570 - syscall_get_arch() 571 - syscall_get_arguments() 572 - syscall_rollback() 573 - syscall_set_return_value() 574 - SIGSYS siginfo_t support 575 - secure_computing is called from a ptrace_event()-safe context 576 - secure_computing return value is checked and a return value of -1 577 results in the system call being skipped immediately. 578 - seccomp syscall wired up 579 - if !HAVE_SPARSE_SYSCALL_NR, have SECCOMP_ARCH_NATIVE, 580 SECCOMP_ARCH_NATIVE_NR, SECCOMP_ARCH_NATIVE_NAME defined. If 581 COMPAT is supported, have the SECCOMP_ARCH_COMPAT* defines too. 582 583config SECCOMP 584 prompt "Enable seccomp to safely execute untrusted bytecode" 585 def_bool y 586 depends on HAVE_ARCH_SECCOMP 587 help 588 This kernel feature is useful for number crunching applications 589 that may need to handle untrusted bytecode during their 590 execution. By using pipes or other transports made available 591 to the process as file descriptors supporting the read/write 592 syscalls, it's possible to isolate those applications in their 593 own address space using seccomp. Once seccomp is enabled via 594 prctl(PR_SET_SECCOMP) or the seccomp() syscall, it cannot be 595 disabled and the task is only allowed to execute a few safe 596 syscalls defined by each seccomp mode. 597 598 If unsure, say Y. 599 600config SECCOMP_FILTER 601 def_bool y 602 depends on HAVE_ARCH_SECCOMP_FILTER && SECCOMP && NET 603 help 604 Enable tasks to build secure computing environments defined 605 in terms of Berkeley Packet Filter programs which implement 606 task-defined system call filtering polices. 607 608 See Documentation/userspace-api/seccomp_filter.rst for details. 609 610config SECCOMP_CACHE_DEBUG 611 bool "Show seccomp filter cache status in /proc/pid/seccomp_cache" 612 depends on SECCOMP_FILTER && !HAVE_SPARSE_SYSCALL_NR 613 depends on PROC_FS 614 help 615 This enables the /proc/pid/seccomp_cache interface to monitor 616 seccomp cache data. The file format is subject to change. Reading 617 the file requires CAP_SYS_ADMIN. 618 619 This option is for debugging only. Enabling presents the risk that 620 an adversary may be able to infer the seccomp filter logic. 621 622 If unsure, say N. 623 624config HAVE_ARCH_STACKLEAK 625 bool 626 help 627 An architecture should select this if it has the code which 628 fills the used part of the kernel stack with the STACKLEAK_POISON 629 value before returning from system calls. 630 631config HAVE_STACKPROTECTOR 632 bool 633 help 634 An arch should select this symbol if: 635 - it has implemented a stack canary (e.g. __stack_chk_guard) 636 637config STACKPROTECTOR 638 bool "Stack Protector buffer overflow detection" 639 depends on HAVE_STACKPROTECTOR 640 depends on $(cc-option,-fstack-protector) 641 default y 642 help 643 This option turns on the "stack-protector" GCC feature. This 644 feature puts, at the beginning of functions, a canary value on 645 the stack just before the return address, and validates 646 the value just before actually returning. Stack based buffer 647 overflows (that need to overwrite this return address) now also 648 overwrite the canary, which gets detected and the attack is then 649 neutralized via a kernel panic. 650 651 Functions will have the stack-protector canary logic added if they 652 have an 8-byte or larger character array on the stack. 653 654 This feature requires gcc version 4.2 or above, or a distribution 655 gcc with the feature backported ("-fstack-protector"). 656 657 On an x86 "defconfig" build, this feature adds canary checks to 658 about 3% of all kernel functions, which increases kernel code size 659 by about 0.3%. 660 661config STACKPROTECTOR_STRONG 662 bool "Strong Stack Protector" 663 depends on STACKPROTECTOR 664 depends on $(cc-option,-fstack-protector-strong) 665 default y 666 help 667 Functions will have the stack-protector canary logic added in any 668 of the following conditions: 669 670 - local variable's address used as part of the right hand side of an 671 assignment or function argument 672 - local variable is an array (or union containing an array), 673 regardless of array type or length 674 - uses register local variables 675 676 This feature requires gcc version 4.9 or above, or a distribution 677 gcc with the feature backported ("-fstack-protector-strong"). 678 679 On an x86 "defconfig" build, this feature adds canary checks to 680 about 20% of all kernel functions, which increases the kernel code 681 size by about 2%. 682 683config ARCH_SUPPORTS_SHADOW_CALL_STACK 684 bool 685 help 686 An architecture should select this if it supports the compiler's 687 Shadow Call Stack and implements runtime support for shadow stack 688 switching. 689 690config SHADOW_CALL_STACK 691 bool "Shadow Call Stack" 692 depends on ARCH_SUPPORTS_SHADOW_CALL_STACK 693 depends on DYNAMIC_FTRACE_WITH_ARGS || DYNAMIC_FTRACE_WITH_REGS || !FUNCTION_GRAPH_TRACER 694 help 695 This option enables the compiler's Shadow Call Stack, which 696 uses a shadow stack to protect function return addresses from 697 being overwritten by an attacker. More information can be found 698 in the compiler's documentation: 699 700 - Clang: https://clang.llvm.org/docs/ShadowCallStack.html 701 - GCC: https://gcc.gnu.org/onlinedocs/gcc/Instrumentation-Options.html#Instrumentation-Options 702 703 Note that security guarantees in the kernel differ from the 704 ones documented for user space. The kernel must store addresses 705 of shadow stacks in memory, which means an attacker capable of 706 reading and writing arbitrary memory may be able to locate them 707 and hijack control flow by modifying the stacks. 708 709config DYNAMIC_SCS 710 bool 711 help 712 Set by the arch code if it relies on code patching to insert the 713 shadow call stack push and pop instructions rather than on the 714 compiler. 715 716config LTO 717 bool 718 help 719 Selected if the kernel will be built using the compiler's LTO feature. 720 721config LTO_CLANG 722 bool 723 select LTO 724 help 725 Selected if the kernel will be built using Clang's LTO feature. 726 727config ARCH_SUPPORTS_LTO_CLANG 728 bool 729 help 730 An architecture should select this option if it supports: 731 - compiling with Clang, 732 - compiling inline assembly with Clang's integrated assembler, 733 - and linking with LLD. 734 735config ARCH_SUPPORTS_LTO_CLANG_THIN 736 bool 737 help 738 An architecture should select this option if it can support Clang's 739 ThinLTO mode. 740 741config HAS_LTO_CLANG 742 def_bool y 743 depends on CC_IS_CLANG && LD_IS_LLD && AS_IS_LLVM 744 depends on $(success,$(NM) --help | head -n 1 | grep -qi llvm) 745 depends on $(success,$(AR) --help | head -n 1 | grep -qi llvm) 746 depends on ARCH_SUPPORTS_LTO_CLANG 747 depends on !FTRACE_MCOUNT_USE_RECORDMCOUNT 748 depends on !KASAN || KASAN_HW_TAGS 749 depends on !GCOV_KERNEL 750 help 751 The compiler and Kconfig options support building with Clang's 752 LTO. 753 754choice 755 prompt "Link Time Optimization (LTO)" 756 default LTO_NONE 757 help 758 This option enables Link Time Optimization (LTO), which allows the 759 compiler to optimize binaries globally. 760 761 If unsure, select LTO_NONE. Note that LTO is very resource-intensive 762 so it's disabled by default. 763 764config LTO_NONE 765 bool "None" 766 help 767 Build the kernel normally, without Link Time Optimization (LTO). 768 769config LTO_CLANG_FULL 770 bool "Clang Full LTO (EXPERIMENTAL)" 771 depends on HAS_LTO_CLANG 772 depends on !COMPILE_TEST 773 select LTO_CLANG 774 help 775 This option enables Clang's full Link Time Optimization (LTO), which 776 allows the compiler to optimize the kernel globally. If you enable 777 this option, the compiler generates LLVM bitcode instead of ELF 778 object files, and the actual compilation from bitcode happens at 779 the LTO link step, which may take several minutes depending on the 780 kernel configuration. More information can be found from LLVM's 781 documentation: 782 783 https://llvm.org/docs/LinkTimeOptimization.html 784 785 During link time, this option can use a large amount of RAM, and 786 may take much longer than the ThinLTO option. 787 788config LTO_CLANG_THIN 789 bool "Clang ThinLTO (EXPERIMENTAL)" 790 depends on HAS_LTO_CLANG && ARCH_SUPPORTS_LTO_CLANG_THIN 791 select LTO_CLANG 792 help 793 This option enables Clang's ThinLTO, which allows for parallel 794 optimization and faster incremental compiles compared to the 795 CONFIG_LTO_CLANG_FULL option. More information can be found 796 from Clang's documentation: 797 798 https://clang.llvm.org/docs/ThinLTO.html 799 800 If unsure, say Y. 801endchoice 802 803config ARCH_SUPPORTS_CFI_CLANG 804 bool 805 help 806 An architecture should select this option if it can support Clang's 807 Control-Flow Integrity (CFI) checking. 808 809config ARCH_USES_CFI_TRAPS 810 bool 811 812config CFI_CLANG 813 bool "Use Clang's Control Flow Integrity (CFI)" 814 depends on ARCH_SUPPORTS_CFI_CLANG 815 depends on $(cc-option,-fsanitize=kcfi) 816 help 817 This option enables Clang’s forward-edge Control Flow Integrity 818 (CFI) checking, where the compiler injects a runtime check to each 819 indirect function call to ensure the target is a valid function with 820 the correct static type. This restricts possible call targets and 821 makes it more difficult for an attacker to exploit bugs that allow 822 the modification of stored function pointers. More information can be 823 found from Clang's documentation: 824 825 https://clang.llvm.org/docs/ControlFlowIntegrity.html 826 827config CFI_PERMISSIVE 828 bool "Use CFI in permissive mode" 829 depends on CFI_CLANG 830 help 831 When selected, Control Flow Integrity (CFI) violations result in a 832 warning instead of a kernel panic. This option should only be used 833 for finding indirect call type mismatches during development. 834 835 If unsure, say N. 836 837config HAVE_ARCH_WITHIN_STACK_FRAMES 838 bool 839 help 840 An architecture should select this if it can walk the kernel stack 841 frames to determine if an object is part of either the arguments 842 or local variables (i.e. that it excludes saved return addresses, 843 and similar) by implementing an inline arch_within_stack_frames(), 844 which is used by CONFIG_HARDENED_USERCOPY. 845 846config HAVE_CONTEXT_TRACKING_USER 847 bool 848 help 849 Provide kernel/user boundaries probes necessary for subsystems 850 that need it, such as userspace RCU extended quiescent state. 851 Syscalls need to be wrapped inside user_exit()-user_enter(), either 852 optimized behind static key or through the slow path using TIF_NOHZ 853 flag. Exceptions handlers must be wrapped as well. Irqs are already 854 protected inside ct_irq_enter/ct_irq_exit() but preemption or signal 855 handling on irq exit still need to be protected. 856 857config HAVE_CONTEXT_TRACKING_USER_OFFSTACK 858 bool 859 help 860 Architecture neither relies on exception_enter()/exception_exit() 861 nor on schedule_user(). Also preempt_schedule_notrace() and 862 preempt_schedule_irq() can't be called in a preemptible section 863 while context tracking is CONTEXT_USER. This feature reflects a sane 864 entry implementation where the following requirements are met on 865 critical entry code, ie: before user_exit() or after user_enter(): 866 867 - Critical entry code isn't preemptible (or better yet: 868 not interruptible). 869 - No use of RCU read side critical sections, unless ct_nmi_enter() 870 got called. 871 - No use of instrumentation, unless instrumentation_begin() got 872 called. 873 874config HAVE_TIF_NOHZ 875 bool 876 help 877 Arch relies on TIF_NOHZ and syscall slow path to implement context 878 tracking calls to user_enter()/user_exit(). 879 880config HAVE_VIRT_CPU_ACCOUNTING 881 bool 882 883config HAVE_VIRT_CPU_ACCOUNTING_IDLE 884 bool 885 help 886 Architecture has its own way to account idle CPU time and therefore 887 doesn't implement vtime_account_idle(). 888 889config ARCH_HAS_SCALED_CPUTIME 890 bool 891 892config HAVE_VIRT_CPU_ACCOUNTING_GEN 893 bool 894 default y if 64BIT 895 help 896 With VIRT_CPU_ACCOUNTING_GEN, cputime_t becomes 64-bit. 897 Before enabling this option, arch code must be audited 898 to ensure there are no races in concurrent read/write of 899 cputime_t. For example, reading/writing 64-bit cputime_t on 900 some 32-bit arches may require multiple accesses, so proper 901 locking is needed to protect against concurrent accesses. 902 903config HAVE_IRQ_TIME_ACCOUNTING 904 bool 905 help 906 Archs need to ensure they use a high enough resolution clock to 907 support irq time accounting and then call enable_sched_clock_irqtime(). 908 909config HAVE_MOVE_PUD 910 bool 911 help 912 Architectures that select this are able to move page tables at the 913 PUD level. If there are only 3 page table levels, the move effectively 914 happens at the PGD level. 915 916config HAVE_MOVE_PMD 917 bool 918 help 919 Archs that select this are able to move page tables at the PMD level. 920 921config HAVE_ARCH_TRANSPARENT_HUGEPAGE 922 bool 923 924config HAVE_ARCH_TRANSPARENT_HUGEPAGE_PUD 925 bool 926 927config HAVE_ARCH_HUGE_VMAP 928 bool 929 930# 931# Archs that select this would be capable of PMD-sized vmaps (i.e., 932# arch_vmap_pmd_supported() returns true). The VM_ALLOW_HUGE_VMAP flag 933# must be used to enable allocations to use hugepages. 934# 935config HAVE_ARCH_HUGE_VMALLOC 936 depends on HAVE_ARCH_HUGE_VMAP 937 bool 938 939config ARCH_WANT_HUGE_PMD_SHARE 940 bool 941 942# Archs that want to use pmd_mkwrite on kernel memory need it defined even 943# if there are no userspace memory management features that use it 944config ARCH_WANT_KERNEL_PMD_MKWRITE 945 bool 946 947config ARCH_WANT_PMD_MKWRITE 948 def_bool TRANSPARENT_HUGEPAGE || ARCH_WANT_KERNEL_PMD_MKWRITE 949 950config HAVE_ARCH_SOFT_DIRTY 951 bool 952 953config HAVE_MOD_ARCH_SPECIFIC 954 bool 955 help 956 The arch uses struct mod_arch_specific to store data. Many arches 957 just need a simple module loader without arch specific data - those 958 should not enable this. 959 960config MODULES_USE_ELF_RELA 961 bool 962 help 963 Modules only use ELF RELA relocations. Modules with ELF REL 964 relocations will give an error. 965 966config MODULES_USE_ELF_REL 967 bool 968 help 969 Modules only use ELF REL relocations. Modules with ELF RELA 970 relocations will give an error. 971 972config ARCH_WANTS_MODULES_DATA_IN_VMALLOC 973 bool 974 help 975 For architectures like powerpc/32 which have constraints on module 976 allocation and need to allocate module data outside of module area. 977 978config HAVE_IRQ_EXIT_ON_IRQ_STACK 979 bool 980 help 981 Architecture doesn't only execute the irq handler on the irq stack 982 but also irq_exit(). This way we can process softirqs on this irq 983 stack instead of switching to a new one when we call __do_softirq() 984 in the end of an hardirq. 985 This spares a stack switch and improves cache usage on softirq 986 processing. 987 988config HAVE_SOFTIRQ_ON_OWN_STACK 989 bool 990 help 991 Architecture provides a function to run __do_softirq() on a 992 separate stack. 993 994config SOFTIRQ_ON_OWN_STACK 995 def_bool HAVE_SOFTIRQ_ON_OWN_STACK && !PREEMPT_RT 996 997config ALTERNATE_USER_ADDRESS_SPACE 998 bool 999 help 1000 Architectures set this when the CPU uses separate address 1001 spaces for kernel and user space pointers. In this case, the 1002 access_ok() check on a __user pointer is skipped. 1003 1004config PGTABLE_LEVELS 1005 int 1006 default 2 1007 1008config ARCH_HAS_ELF_RANDOMIZE 1009 bool 1010 help 1011 An architecture supports choosing randomized locations for 1012 stack, mmap, brk, and ET_DYN. Defined functions: 1013 - arch_mmap_rnd() 1014 - arch_randomize_brk() 1015 1016config HAVE_ARCH_MMAP_RND_BITS 1017 bool 1018 help 1019 An arch should select this symbol if it supports setting a variable 1020 number of bits for use in establishing the base address for mmap 1021 allocations, has MMU enabled and provides values for both: 1022 - ARCH_MMAP_RND_BITS_MIN 1023 - ARCH_MMAP_RND_BITS_MAX 1024 1025config HAVE_EXIT_THREAD 1026 bool 1027 help 1028 An architecture implements exit_thread. 1029 1030config ARCH_MMAP_RND_BITS_MIN 1031 int 1032 1033config ARCH_MMAP_RND_BITS_MAX 1034 int 1035 1036config ARCH_MMAP_RND_BITS_DEFAULT 1037 int 1038 1039config ARCH_MMAP_RND_BITS 1040 int "Number of bits to use for ASLR of mmap base address" if EXPERT 1041 range ARCH_MMAP_RND_BITS_MIN ARCH_MMAP_RND_BITS_MAX 1042 default ARCH_MMAP_RND_BITS_DEFAULT if ARCH_MMAP_RND_BITS_DEFAULT 1043 default ARCH_MMAP_RND_BITS_MIN 1044 depends on HAVE_ARCH_MMAP_RND_BITS 1045 help 1046 This value can be used to select the number of bits to use to 1047 determine the random offset to the base address of vma regions 1048 resulting from mmap allocations. This value will be bounded 1049 by the architecture's minimum and maximum supported values. 1050 1051 This value can be changed after boot using the 1052 /proc/sys/vm/mmap_rnd_bits tunable 1053 1054config HAVE_ARCH_MMAP_RND_COMPAT_BITS 1055 bool 1056 help 1057 An arch should select this symbol if it supports running applications 1058 in compatibility mode, supports setting a variable number of bits for 1059 use in establishing the base address for mmap allocations, has MMU 1060 enabled and provides values for both: 1061 - ARCH_MMAP_RND_COMPAT_BITS_MIN 1062 - ARCH_MMAP_RND_COMPAT_BITS_MAX 1063 1064config ARCH_MMAP_RND_COMPAT_BITS_MIN 1065 int 1066 1067config ARCH_MMAP_RND_COMPAT_BITS_MAX 1068 int 1069 1070config ARCH_MMAP_RND_COMPAT_BITS_DEFAULT 1071 int 1072 1073config ARCH_MMAP_RND_COMPAT_BITS 1074 int "Number of bits to use for ASLR of mmap base address for compatible applications" if EXPERT 1075 range ARCH_MMAP_RND_COMPAT_BITS_MIN ARCH_MMAP_RND_COMPAT_BITS_MAX 1076 default ARCH_MMAP_RND_COMPAT_BITS_DEFAULT if ARCH_MMAP_RND_COMPAT_BITS_DEFAULT 1077 default ARCH_MMAP_RND_COMPAT_BITS_MIN 1078 depends on HAVE_ARCH_MMAP_RND_COMPAT_BITS 1079 help 1080 This value can be used to select the number of bits to use to 1081 determine the random offset to the base address of vma regions 1082 resulting from mmap allocations for compatible applications This 1083 value will be bounded by the architecture's minimum and maximum 1084 supported values. 1085 1086 This value can be changed after boot using the 1087 /proc/sys/vm/mmap_rnd_compat_bits tunable 1088 1089config HAVE_ARCH_COMPAT_MMAP_BASES 1090 bool 1091 help 1092 This allows 64bit applications to invoke 32-bit mmap() syscall 1093 and vice-versa 32-bit applications to call 64-bit mmap(). 1094 Required for applications doing different bitness syscalls. 1095 1096config PAGE_SIZE_LESS_THAN_64KB 1097 def_bool y 1098 depends on !ARM64_64K_PAGES 1099 depends on !IA64_PAGE_SIZE_64KB 1100 depends on !PAGE_SIZE_64KB 1101 depends on !PARISC_PAGE_SIZE_64KB 1102 depends on PAGE_SIZE_LESS_THAN_256KB 1103 1104config PAGE_SIZE_LESS_THAN_256KB 1105 def_bool y 1106 depends on !PAGE_SIZE_256KB 1107 1108# This allows to use a set of generic functions to determine mmap base 1109# address by giving priority to top-down scheme only if the process 1110# is not in legacy mode (compat task, unlimited stack size or 1111# sysctl_legacy_va_layout). 1112# Architecture that selects this option can provide its own version of: 1113# - STACK_RND_MASK 1114config ARCH_WANT_DEFAULT_TOPDOWN_MMAP_LAYOUT 1115 bool 1116 depends on MMU 1117 select ARCH_HAS_ELF_RANDOMIZE 1118 1119config HAVE_OBJTOOL 1120 bool 1121 1122config HAVE_JUMP_LABEL_HACK 1123 bool 1124 1125config HAVE_NOINSTR_HACK 1126 bool 1127 1128config HAVE_NOINSTR_VALIDATION 1129 bool 1130 1131config HAVE_UACCESS_VALIDATION 1132 bool 1133 select OBJTOOL 1134 1135config HAVE_STACK_VALIDATION 1136 bool 1137 help 1138 Architecture supports objtool compile-time frame pointer rule 1139 validation. 1140 1141config HAVE_RELIABLE_STACKTRACE 1142 bool 1143 help 1144 Architecture has either save_stack_trace_tsk_reliable() or 1145 arch_stack_walk_reliable() function which only returns a stack trace 1146 if it can guarantee the trace is reliable. 1147 1148config HAVE_ARCH_HASH 1149 bool 1150 default n 1151 help 1152 If this is set, the architecture provides an <asm/hash.h> 1153 file which provides platform-specific implementations of some 1154 functions in <linux/hash.h> or fs/namei.c. 1155 1156config HAVE_ARCH_NVRAM_OPS 1157 bool 1158 1159config ISA_BUS_API 1160 def_bool ISA 1161 1162# 1163# ABI hall of shame 1164# 1165config CLONE_BACKWARDS 1166 bool 1167 help 1168 Architecture has tls passed as the 4th argument of clone(2), 1169 not the 5th one. 1170 1171config CLONE_BACKWARDS2 1172 bool 1173 help 1174 Architecture has the first two arguments of clone(2) swapped. 1175 1176config CLONE_BACKWARDS3 1177 bool 1178 help 1179 Architecture has tls passed as the 3rd argument of clone(2), 1180 not the 5th one. 1181 1182config ODD_RT_SIGACTION 1183 bool 1184 help 1185 Architecture has unusual rt_sigaction(2) arguments 1186 1187config OLD_SIGSUSPEND 1188 bool 1189 help 1190 Architecture has old sigsuspend(2) syscall, of one-argument variety 1191 1192config OLD_SIGSUSPEND3 1193 bool 1194 help 1195 Even weirder antique ABI - three-argument sigsuspend(2) 1196 1197config OLD_SIGACTION 1198 bool 1199 help 1200 Architecture has old sigaction(2) syscall. Nope, not the same 1201 as OLD_SIGSUSPEND | OLD_SIGSUSPEND3 - alpha has sigsuspend(2), 1202 but fairly different variant of sigaction(2), thanks to OSF/1 1203 compatibility... 1204 1205config COMPAT_OLD_SIGACTION 1206 bool 1207 1208config COMPAT_32BIT_TIME 1209 bool "Provide system calls for 32-bit time_t" 1210 default !64BIT || COMPAT 1211 help 1212 This enables 32 bit time_t support in addition to 64 bit time_t support. 1213 This is relevant on all 32-bit architectures, and 64-bit architectures 1214 as part of compat syscall handling. 1215 1216config ARCH_NO_PREEMPT 1217 bool 1218 1219config ARCH_SUPPORTS_RT 1220 bool 1221 1222config CPU_NO_EFFICIENT_FFS 1223 def_bool n 1224 1225config HAVE_ARCH_VMAP_STACK 1226 def_bool n 1227 help 1228 An arch should select this symbol if it can support kernel stacks 1229 in vmalloc space. This means: 1230 1231 - vmalloc space must be large enough to hold many kernel stacks. 1232 This may rule out many 32-bit architectures. 1233 1234 - Stacks in vmalloc space need to work reliably. For example, if 1235 vmap page tables are created on demand, either this mechanism 1236 needs to work while the stack points to a virtual address with 1237 unpopulated page tables or arch code (switch_to() and switch_mm(), 1238 most likely) needs to ensure that the stack's page table entries 1239 are populated before running on a possibly unpopulated stack. 1240 1241 - If the stack overflows into a guard page, something reasonable 1242 should happen. The definition of "reasonable" is flexible, but 1243 instantly rebooting without logging anything would be unfriendly. 1244 1245config VMAP_STACK 1246 default y 1247 bool "Use a virtually-mapped stack" 1248 depends on HAVE_ARCH_VMAP_STACK 1249 depends on !KASAN || KASAN_HW_TAGS || KASAN_VMALLOC 1250 help 1251 Enable this if you want the use virtually-mapped kernel stacks 1252 with guard pages. This causes kernel stack overflows to be 1253 caught immediately rather than causing difficult-to-diagnose 1254 corruption. 1255 1256 To use this with software KASAN modes, the architecture must support 1257 backing virtual mappings with real shadow memory, and KASAN_VMALLOC 1258 must be enabled. 1259 1260config HAVE_ARCH_RANDOMIZE_KSTACK_OFFSET 1261 def_bool n 1262 help 1263 An arch should select this symbol if it can support kernel stack 1264 offset randomization with calls to add_random_kstack_offset() 1265 during syscall entry and choose_random_kstack_offset() during 1266 syscall exit. Careful removal of -fstack-protector-strong and 1267 -fstack-protector should also be applied to the entry code and 1268 closely examined, as the artificial stack bump looks like an array 1269 to the compiler, so it will attempt to add canary checks regardless 1270 of the static branch state. 1271 1272config RANDOMIZE_KSTACK_OFFSET 1273 bool "Support for randomizing kernel stack offset on syscall entry" if EXPERT 1274 default y 1275 depends on HAVE_ARCH_RANDOMIZE_KSTACK_OFFSET 1276 depends on INIT_STACK_NONE || !CC_IS_CLANG || CLANG_VERSION >= 140000 1277 help 1278 The kernel stack offset can be randomized (after pt_regs) by 1279 roughly 5 bits of entropy, frustrating memory corruption 1280 attacks that depend on stack address determinism or 1281 cross-syscall address exposures. 1282 1283 The feature is controlled via the "randomize_kstack_offset=on/off" 1284 kernel boot param, and if turned off has zero overhead due to its use 1285 of static branches (see JUMP_LABEL). 1286 1287 If unsure, say Y. 1288 1289config RANDOMIZE_KSTACK_OFFSET_DEFAULT 1290 bool "Default state of kernel stack offset randomization" 1291 depends on RANDOMIZE_KSTACK_OFFSET 1292 help 1293 Kernel stack offset randomization is controlled by kernel boot param 1294 "randomize_kstack_offset=on/off", and this config chooses the default 1295 boot state. 1296 1297config ARCH_OPTIONAL_KERNEL_RWX 1298 def_bool n 1299 1300config ARCH_OPTIONAL_KERNEL_RWX_DEFAULT 1301 def_bool n 1302 1303config ARCH_HAS_STRICT_KERNEL_RWX 1304 def_bool n 1305 1306config STRICT_KERNEL_RWX 1307 bool "Make kernel text and rodata read-only" if ARCH_OPTIONAL_KERNEL_RWX 1308 depends on ARCH_HAS_STRICT_KERNEL_RWX 1309 default !ARCH_OPTIONAL_KERNEL_RWX || ARCH_OPTIONAL_KERNEL_RWX_DEFAULT 1310 help 1311 If this is set, kernel text and rodata memory will be made read-only, 1312 and non-text memory will be made non-executable. This provides 1313 protection against certain security exploits (e.g. executing the heap 1314 or modifying text) 1315 1316 These features are considered standard security practice these days. 1317 You should say Y here in almost all cases. 1318 1319config ARCH_HAS_STRICT_MODULE_RWX 1320 def_bool n 1321 1322config STRICT_MODULE_RWX 1323 bool "Set loadable kernel module data as NX and text as RO" if ARCH_OPTIONAL_KERNEL_RWX 1324 depends on ARCH_HAS_STRICT_MODULE_RWX && MODULES 1325 default !ARCH_OPTIONAL_KERNEL_RWX || ARCH_OPTIONAL_KERNEL_RWX_DEFAULT 1326 help 1327 If this is set, module text and rodata memory will be made read-only, 1328 and non-text memory will be made non-executable. This provides 1329 protection against certain security exploits (e.g. writing to text) 1330 1331# select if the architecture provides an asm/dma-direct.h header 1332config ARCH_HAS_PHYS_TO_DMA 1333 bool 1334 1335config HAVE_ARCH_COMPILER_H 1336 bool 1337 help 1338 An architecture can select this if it provides an 1339 asm/compiler.h header that should be included after 1340 linux/compiler-*.h in order to override macro definitions that those 1341 headers generally provide. 1342 1343config HAVE_ARCH_PREL32_RELOCATIONS 1344 bool 1345 help 1346 May be selected by an architecture if it supports place-relative 1347 32-bit relocations, both in the toolchain and in the module loader, 1348 in which case relative references can be used in special sections 1349 for PCI fixup, initcalls etc which are only half the size on 64 bit 1350 architectures, and don't require runtime relocation on relocatable 1351 kernels. 1352 1353config ARCH_USE_MEMREMAP_PROT 1354 bool 1355 1356config LOCK_EVENT_COUNTS 1357 bool "Locking event counts collection" 1358 depends on DEBUG_FS 1359 help 1360 Enable light-weight counting of various locking related events 1361 in the system with minimal performance impact. This reduces 1362 the chance of application behavior change because of timing 1363 differences. The counts are reported via debugfs. 1364 1365# Select if the architecture has support for applying RELR relocations. 1366config ARCH_HAS_RELR 1367 bool 1368 1369config RELR 1370 bool "Use RELR relocation packing" 1371 depends on ARCH_HAS_RELR && TOOLS_SUPPORT_RELR 1372 default y 1373 help 1374 Store the kernel's dynamic relocations in the RELR relocation packing 1375 format. Requires a compatible linker (LLD supports this feature), as 1376 well as compatible NM and OBJCOPY utilities (llvm-nm and llvm-objcopy 1377 are compatible). 1378 1379config ARCH_HAS_MEM_ENCRYPT 1380 bool 1381 1382config ARCH_HAS_CC_PLATFORM 1383 bool 1384 1385config HAVE_SPARSE_SYSCALL_NR 1386 bool 1387 help 1388 An architecture should select this if its syscall numbering is sparse 1389 to save space. For example, MIPS architecture has a syscall array with 1390 entries at 4000, 5000 and 6000 locations. This option turns on syscall 1391 related optimizations for a given architecture. 1392 1393config ARCH_HAS_VDSO_DATA 1394 bool 1395 1396config HAVE_STATIC_CALL 1397 bool 1398 1399config HAVE_STATIC_CALL_INLINE 1400 bool 1401 depends on HAVE_STATIC_CALL 1402 select OBJTOOL 1403 1404config HAVE_PREEMPT_DYNAMIC 1405 bool 1406 1407config HAVE_PREEMPT_DYNAMIC_CALL 1408 bool 1409 depends on HAVE_STATIC_CALL 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 calls. 1414 1415 Where an architecture selects HAVE_STATIC_CALL_INLINE, any call to a 1416 preemption function will be patched directly. 1417 1418 Where an architecture does not select HAVE_STATIC_CALL_INLINE, any 1419 call to a preemption function will go through a trampoline, and the 1420 trampoline will be patched. 1421 1422 It is strongly advised to support inline static call to avoid any 1423 overhead. 1424 1425config HAVE_PREEMPT_DYNAMIC_KEY 1426 bool 1427 depends on HAVE_ARCH_JUMP_LABEL 1428 select HAVE_PREEMPT_DYNAMIC 1429 help 1430 An architecture should select this if it can handle the preemption 1431 model being selected at boot time using static keys. 1432 1433 Each preemption function will be given an early return based on a 1434 static key. This should have slightly lower overhead than non-inline 1435 static calls, as this effectively inlines each trampoline into the 1436 start of its callee. This may avoid redundant work, and may 1437 integrate better with CFI schemes. 1438 1439 This will have greater overhead than using inline static calls as 1440 the call to the preemption function cannot be entirely elided. 1441 1442config ARCH_WANT_LD_ORPHAN_WARN 1443 bool 1444 help 1445 An arch should select this symbol once all linker sections are explicitly 1446 included, size-asserted, or discarded in the linker scripts. This is 1447 important because we never want expected sections to be placed heuristically 1448 by the linker, since the locations of such sections can change between linker 1449 versions. 1450 1451config HAVE_ARCH_PFN_VALID 1452 bool 1453 1454config ARCH_SUPPORTS_DEBUG_PAGEALLOC 1455 bool 1456 1457config ARCH_SUPPORTS_PAGE_TABLE_CHECK 1458 bool 1459 1460config ARCH_SPLIT_ARG64 1461 bool 1462 help 1463 If a 32-bit architecture requires 64-bit arguments to be split into 1464 pairs of 32-bit arguments, select this option. 1465 1466config ARCH_HAS_ELFCORE_COMPAT 1467 bool 1468 1469config ARCH_HAS_PARANOID_L1D_FLUSH 1470 bool 1471 1472config ARCH_HAVE_TRACE_MMIO_ACCESS 1473 bool 1474 1475config DYNAMIC_SIGFRAME 1476 bool 1477 1478# Select, if arch has a named attribute group bound to NUMA device nodes. 1479config HAVE_ARCH_NODE_DEV_GROUP 1480 bool 1481 1482config ARCH_HAS_NONLEAF_PMD_YOUNG 1483 bool 1484 help 1485 Architectures that select this option are capable of setting the 1486 accessed bit in non-leaf PMD entries when using them as part of linear 1487 address translations. Page table walkers that clear the accessed bit 1488 may use this capability to reduce their search space. 1489 1490source "kernel/gcov/Kconfig" 1491 1492source "scripts/gcc-plugins/Kconfig" 1493 1494config FUNCTION_ALIGNMENT_4B 1495 bool 1496 1497config FUNCTION_ALIGNMENT_8B 1498 bool 1499 1500config FUNCTION_ALIGNMENT_16B 1501 bool 1502 1503config FUNCTION_ALIGNMENT_32B 1504 bool 1505 1506config FUNCTION_ALIGNMENT_64B 1507 bool 1508 1509config FUNCTION_ALIGNMENT 1510 int 1511 default 64 if FUNCTION_ALIGNMENT_64B 1512 default 32 if FUNCTION_ALIGNMENT_32B 1513 default 16 if FUNCTION_ALIGNMENT_16B 1514 default 8 if FUNCTION_ALIGNMENT_8B 1515 default 4 if FUNCTION_ALIGNMENT_4B 1516 default 0 1517 1518endmenu 1519