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