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