Kconfig

   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
  12config ARCH_CONFIGURES_CPU_MITIGATIONS
  13	bool
  14
  15if !ARCH_CONFIGURES_CPU_MITIGATIONS
  16config CPU_MITIGATIONS
  17	def_bool y
  18endif
  19
  20#
  21# Selected by architectures that need custom DMA operations for e.g. legacy
  22# IOMMUs not handled by dma-iommu.  Drivers must never select this symbol.
  23#
  24config ARCH_HAS_DMA_OPS
  25	depends on HAS_DMA
  26	select DMA_OPS_HELPERS
  27	bool
  28
  29menu "General architecture-dependent options"
  30
  31config ARCH_HAS_SUBPAGE_FAULTS
  32	bool
  33	help
  34	  Select if the architecture can check permissions at sub-page
  35	  granularity (e.g. arm64 MTE). The probe_user_*() functions
  36	  must be implemented.
  37
  38config HOTPLUG_SMT
  39	bool
  40
  41config SMT_NUM_THREADS_DYNAMIC
  42	bool
  43
  44config ARCH_SUPPORTS_SCHED_SMT
  45	bool
  46
  47config ARCH_SUPPORTS_SCHED_CLUSTER
  48	bool
  49
  50config ARCH_SUPPORTS_SCHED_MC
  51	bool
  52
  53config SCHED_SMT
  54	bool "SMT (Hyperthreading) scheduler support"
  55	depends on ARCH_SUPPORTS_SCHED_SMT
  56	default y
  57	help
  58	  Improves the CPU scheduler's decision making when dealing with
  59	  MultiThreading at a cost of slightly increased overhead in some
  60	  places. If unsure say N here.
  61
  62config SCHED_CLUSTER
  63	bool "Cluster scheduler support"
  64	depends on ARCH_SUPPORTS_SCHED_CLUSTER
  65	default y
  66	help
  67	  Cluster scheduler support improves the CPU scheduler's decision
  68	  making when dealing with machines that have clusters of CPUs.
  69	  Cluster usually means a couple of CPUs which are placed closely
  70	  by sharing mid-level caches, last-level cache tags or internal
  71	  busses.
  72
  73config SCHED_MC
  74	bool "Multi-Core Cache (MC) scheduler support"
  75	depends on ARCH_SUPPORTS_SCHED_MC
  76	default y
  77	help
  78	  Multi-core scheduler support improves the CPU scheduler's decision
  79	  making when dealing with multi-core CPU chips at a cost of slightly
  80	  increased overhead in some places. If unsure say N here.
  81
  82# Selected by HOTPLUG_CORE_SYNC_DEAD or HOTPLUG_CORE_SYNC_FULL
  83config HOTPLUG_CORE_SYNC
  84	bool
  85
  86# Basic CPU dead synchronization selected by architecture
  87config HOTPLUG_CORE_SYNC_DEAD
  88	bool
  89	select HOTPLUG_CORE_SYNC
  90
  91# Full CPU synchronization with alive state selected by architecture
  92config HOTPLUG_CORE_SYNC_FULL
  93	bool
  94	select HOTPLUG_CORE_SYNC_DEAD if HOTPLUG_CPU
  95	select HOTPLUG_CORE_SYNC
  96
  97config HOTPLUG_SPLIT_STARTUP
  98	bool
  99	select HOTPLUG_CORE_SYNC_FULL
 100
 101config HOTPLUG_PARALLEL
 102	bool
 103	select HOTPLUG_SPLIT_STARTUP
 104
 105config GENERIC_IRQ_ENTRY
 106	bool
 107
 108config GENERIC_SYSCALL
 109	bool
 110	depends on GENERIC_IRQ_ENTRY
 111
 112config GENERIC_ENTRY
 113	bool
 114	select GENERIC_IRQ_ENTRY
 115	select GENERIC_SYSCALL
 116
 117config KPROBES
 118	bool "Kprobes"
 119	depends on HAVE_KPROBES
 120	select KALLSYMS
 121	select EXECMEM
 122	select NEED_TASKS_RCU
 123	help
 124	  Kprobes allows you to trap at almost any kernel address and
 125	  execute a callback function.  register_kprobe() establishes
 126	  a probepoint and specifies the callback.  Kprobes is useful
 127	  for kernel debugging, non-intrusive instrumentation and testing.
 128	  If in doubt, say "N".
 129
 130config JUMP_LABEL
 131	bool "Optimize very unlikely/likely branches"
 132	depends on HAVE_ARCH_JUMP_LABEL
 133	select OBJTOOL if HAVE_JUMP_LABEL_HACK
 134	help
 135	  This option enables a transparent branch optimization that
 136	  makes certain almost-always-true or almost-always-false branch
 137	  conditions even cheaper to execute within the kernel.
 138
 139	  Certain performance-sensitive kernel code, such as trace points,
 140	  scheduler functionality, networking code and KVM have such
 141	  branches and include support for this optimization technique.
 142
 143	  If it is detected that the compiler has support for "asm goto",
 144	  the kernel will compile such branches with just a nop
 145	  instruction. When the condition flag is toggled to true, the
 146	  nop will be converted to a jump instruction to execute the
 147	  conditional block of instructions.
 148
 149	  This technique lowers overhead and stress on the branch prediction
 150	  of the processor and generally makes the kernel faster. The update
 151	  of the condition is slower, but those are always very rare.
 152
 153	  ( On 32-bit x86, the necessary options added to the compiler
 154	    flags may increase the size of the kernel slightly. )
 155
 156config STATIC_KEYS_SELFTEST
 157	bool "Static key selftest"
 158	depends on JUMP_LABEL
 159	help
 160	  Boot time self-test of the branch patching code.
 161
 162config STATIC_CALL_SELFTEST
 163	bool "Static call selftest"
 164	depends on HAVE_STATIC_CALL
 165	help
 166	  Boot time self-test of the call patching code.
 167
 168config OPTPROBES
 169	def_bool y
 170	depends on KPROBES && HAVE_OPTPROBES
 171	select NEED_TASKS_RCU
 172
 173config KPROBES_ON_FTRACE
 174	def_bool y
 175	depends on KPROBES && HAVE_KPROBES_ON_FTRACE
 176	depends on DYNAMIC_FTRACE_WITH_REGS
 177	help
 178	  If function tracer is enabled and the arch supports full
 179	  passing of pt_regs to function tracing, then kprobes can
 180	  optimize on top of function tracing.
 181
 182config UPROBES
 183	def_bool n
 184	depends on ARCH_SUPPORTS_UPROBES
 185	select TASKS_TRACE_RCU
 186	help
 187	  Uprobes is the user-space counterpart to kprobes: they
 188	  enable instrumentation applications (such as 'perf probe')
 189	  to establish unintrusive probes in user-space binaries and
 190	  libraries, by executing handler functions when the probes
 191	  are hit by user-space applications.
 192
 193	  ( These probes come in the form of single-byte breakpoints,
 194	    managed by the kernel and kept transparent to the probed
 195	    application. )
 196
 197config HAVE_64BIT_ALIGNED_ACCESS
 198	def_bool 64BIT && !HAVE_EFFICIENT_UNALIGNED_ACCESS
 199	help
 200	  Some architectures require 64 bit accesses to be 64 bit
 201	  aligned, which also requires structs containing 64 bit values
 202	  to be 64 bit aligned too. This includes some 32 bit
 203	  architectures which can do 64 bit accesses, as well as 64 bit
 204	  architectures without unaligned access.
 205
 206	  This symbol should be selected by an architecture if 64 bit
 207	  accesses are required to be 64 bit aligned in this way even
 208	  though it is not a 64 bit architecture.
 209
 210	  See Documentation/core-api/unaligned-memory-access.rst for
 211	  more information on the topic of unaligned memory accesses.
 212
 213config HAVE_EFFICIENT_UNALIGNED_ACCESS
 214	bool
 215	help
 216	  Some architectures are unable to perform unaligned accesses
 217	  without the use of get_unaligned/put_unaligned. Others are
 218	  unable to perform such accesses efficiently (e.g. trap on
 219	  unaligned access and require fixing it up in the exception
 220	  handler.)
 221
 222	  This symbol should be selected by an architecture if it can
 223	  perform unaligned accesses efficiently to allow different
 224	  code paths to be selected for these cases. Some network
 225	  drivers, for example, could opt to not fix up alignment
 226	  problems with received packets if doing so would not help
 227	  much.
 228
 229	  See Documentation/core-api/unaligned-memory-access.rst for more
 230	  information on the topic of unaligned memory accesses.
 231
 232config ARCH_USE_BUILTIN_BSWAP
 233	bool
 234	help
 235	  GCC and Clang have builtin functions for handling byte-swapping.
 236	  Using these allows the compiler to see what's happening and
 237	  offers more opportunity for optimisation. In particular, the
 238	  compiler will be able to combine the byteswap with a nearby load
 239	  or store and use load-and-swap or store-and-swap instructions if
 240	  the architecture has them. It should almost *never* result in code
 241	  which is worse than the hand-coded assembler in <asm/swab.h>.
 242	  But just in case it does, the use of the builtins is optional.
 243
 244	  Any architecture with load-and-swap or store-and-swap
 245	  instructions should set this. And it shouldn't hurt to set it
 246	  on architectures that don't have such instructions.
 247
 248config KRETPROBES
 249	def_bool y
 250	depends on KPROBES && (HAVE_KRETPROBES || HAVE_RETHOOK)
 251
 252config KRETPROBE_ON_RETHOOK
 253	def_bool y
 254	depends on HAVE_RETHOOK
 255	depends on KRETPROBES
 256	select RETHOOK
 257
 258config USER_RETURN_NOTIFIER
 259	bool
 260	depends on HAVE_USER_RETURN_NOTIFIER
 261	help
 262	  Provide a kernel-internal notification when a cpu is about to
 263	  switch to user mode.
 264
 265config HAVE_IOREMAP_PROT
 266	bool
 267
 268config HAVE_KPROBES
 269	bool
 270
 271config HAVE_KRETPROBES
 272	bool
 273
 274config HAVE_OPTPROBES
 275	bool
 276
 277config HAVE_KPROBES_ON_FTRACE
 278	bool
 279
 280config ARCH_CORRECT_STACKTRACE_ON_KRETPROBE
 281	bool
 282	help
 283	  Since kretprobes modifies return address on the stack, the
 284	  stacktrace may see the kretprobe trampoline address instead
 285	  of correct one. If the architecture stacktrace code and
 286	  unwinder can adjust such entries, select this configuration.
 287
 288config HAVE_FUNCTION_ERROR_INJECTION
 289	bool
 290
 291config HAVE_NMI
 292	bool
 293
 294config HAVE_FUNCTION_DESCRIPTORS
 295	bool
 296
 297config TRACE_IRQFLAGS_SUPPORT
 298	bool
 299
 300config TRACE_IRQFLAGS_NMI_SUPPORT
 301	bool
 302
 303#
 304# An arch should select this if it provides all these things:
 305#
 306#	task_pt_regs()		in asm/processor.h or asm/ptrace.h
 307#	arch_has_single_step()	if there is hardware single-step support
 308#	arch_has_block_step()	if there is hardware block-step support
 309#	asm/syscall.h		supplying asm-generic/syscall.h interface
 310#	linux/regset.h		user_regset interfaces
 311#	CORE_DUMP_USE_REGSET	#define'd in linux/elf.h
 312#	TIF_SYSCALL_TRACE	calls ptrace_report_syscall_{entry,exit}
 313#	TIF_NOTIFY_RESUME	calls resume_user_mode_work()
 314#
 315config HAVE_ARCH_TRACEHOOK
 316	bool
 317
 318config HAVE_DMA_CONTIGUOUS
 319	bool
 320
 321config GENERIC_SMP_IDLE_THREAD
 322	bool
 323
 324config GENERIC_IDLE_POLL_SETUP
 325	bool
 326
 327config ARCH_HAS_FORTIFY_SOURCE
 328	bool
 329	help
 330	  An architecture should select this when it can successfully
 331	  build and run with CONFIG_FORTIFY_SOURCE.
 332
 333#
 334# Select if the arch provides a historic keepinit alias for the retain_initrd
 335# command line option
 336#
 337config ARCH_HAS_KEEPINITRD
 338	bool
 339
 340# Select if arch has all set_memory_ro/rw/x/nx() functions in asm/cacheflush.h
 341config ARCH_HAS_SET_MEMORY
 342	bool
 343
 344# Select if arch has all set_direct_map_invalid/default() functions
 345config ARCH_HAS_SET_DIRECT_MAP
 346	bool
 347
 348#
 349# Select if the architecture provides the arch_dma_set_uncached symbol to
 350# either provide an uncached segment alias for a DMA allocation, or
 351# to remap the page tables in place.
 352#
 353config ARCH_HAS_DMA_SET_UNCACHED
 354	bool
 355
 356#
 357# Select if the architectures provides the arch_dma_clear_uncached symbol
 358# to undo an in-place page table remap for uncached access.
 359#
 360config ARCH_HAS_DMA_CLEAR_UNCACHED
 361	bool
 362
 363config ARCH_HAS_CPU_FINALIZE_INIT
 364	bool
 365
 366# The architecture has a per-task state that includes the mm's PASID
 367config ARCH_HAS_CPU_PASID
 368	bool
 369	select IOMMU_MM_DATA
 370
 371config HAVE_ARCH_THREAD_STRUCT_WHITELIST
 372	bool
 373	help
 374	  An architecture should select this to provide hardened usercopy
 375	  knowledge about what region of the thread_struct should be
 376	  whitelisted for copying to userspace. Normally this is only the
 377	  FPU registers. Specifically, arch_thread_struct_whitelist()
 378	  should be implemented. Without this, the entire thread_struct
 379	  field in task_struct will be left whitelisted.
 380
 381# Select if arch wants to size task_struct dynamically via arch_task_struct_size:
 382config ARCH_WANTS_DYNAMIC_TASK_STRUCT
 383	bool
 384
 385config ARCH_WANTS_NO_INSTR
 386	bool
 387	help
 388	  An architecture should select this if the noinstr macro is being used on
 389	  functions to denote that the toolchain should avoid instrumenting such
 390	  functions and is required for correctness.
 391
 392config ARCH_32BIT_OFF_T
 393	bool
 394	depends on !64BIT
 395	help
 396	  All new 32-bit architectures should have 64-bit off_t type on
 397	  userspace side which corresponds to the loff_t kernel type. This
 398	  is the requirement for modern ABIs. Some existing architectures
 399	  still support 32-bit off_t. This option is enabled for all such
 400	  architectures explicitly.
 401
 402# Selected by 64 bit architectures which have a 32 bit f_tinode in struct ustat
 403config ARCH_32BIT_USTAT_F_TINODE
 404	bool
 405
 406config HAVE_ASM_MODVERSIONS
 407	bool
 408	help
 409	  This symbol should be selected by an architecture if it provides
 410	  <asm/asm-prototypes.h> to support the module versioning for symbols
 411	  exported from assembly code.
 412
 413config HAVE_REGS_AND_STACK_ACCESS_API
 414	bool
 415	help
 416	  This symbol should be selected by an architecture if it supports
 417	  the API needed to access registers and stack entries from pt_regs,
 418	  declared in asm/ptrace.h
 419	  For example the kprobes-based event tracer needs this API.
 420
 421config HAVE_RSEQ
 422	bool
 423	depends on HAVE_REGS_AND_STACK_ACCESS_API
 424	help
 425	  This symbol should be selected by an architecture if it
 426	  supports an implementation of restartable sequences.
 427
 428config HAVE_RUST
 429	bool
 430	help
 431	  This symbol should be selected by an architecture if it
 432	  supports Rust.
 433
 434config HAVE_FUNCTION_ARG_ACCESS_API
 435	bool
 436	help
 437	  This symbol should be selected by an architecture if it supports
 438	  the API needed to access function arguments from pt_regs,
 439	  declared in asm/ptrace.h
 440
 441config HAVE_HW_BREAKPOINT
 442	bool
 443	depends on PERF_EVENTS
 444
 445config HAVE_MIXED_BREAKPOINTS_REGS
 446	bool
 447	depends on HAVE_HW_BREAKPOINT
 448	help
 449	  Depending on the arch implementation of hardware breakpoints,
 450	  some of them have separate registers for data and instruction
 451	  breakpoints addresses, others have mixed registers to store
 452	  them but define the access type in a control register.
 453	  Select this option if your arch implements breakpoints under the
 454	  latter fashion.
 455
 456config HAVE_USER_RETURN_NOTIFIER
 457	bool
 458
 459config HAVE_PERF_EVENTS_NMI
 460	bool
 461	help
 462	  System hardware can generate an NMI using the perf event
 463	  subsystem.  Also has support for calculating CPU cycle events
 464	  to determine how many clock cycles in a given period.
 465
 466config HAVE_HARDLOCKUP_DETECTOR_PERF
 467	bool
 468	depends on HAVE_PERF_EVENTS_NMI
 469	help
 470	  The arch chooses to use the generic perf-NMI-based hardlockup
 471	  detector. Must define HAVE_PERF_EVENTS_NMI.
 472
 473config HAVE_HARDLOCKUP_DETECTOR_ARCH
 474	bool
 475	help
 476	  The arch provides its own hardlockup detector implementation instead
 477	  of the generic ones.
 478
 479	  It uses the same command line parameters, and sysctl interface,
 480	  as the generic hardlockup detectors.
 481
 482config UNWIND_USER
 483	bool
 484
 485config HAVE_UNWIND_USER_FP
 486	bool
 487	select UNWIND_USER
 488
 489config HAVE_PERF_REGS
 490	bool
 491	help
 492	  Support selective register dumps for perf events. This includes
 493	  bit-mapping of each registers and a unique architecture id.
 494
 495config HAVE_PERF_USER_STACK_DUMP
 496	bool
 497	help
 498	  Support user stack dumps for perf event samples. This needs
 499	  access to the user stack pointer which is not unified across
 500	  architectures.
 501
 502config HAVE_ARCH_JUMP_LABEL
 503	bool
 504
 505config HAVE_ARCH_JUMP_LABEL_RELATIVE
 506	bool
 507
 508config MMU_GATHER_TABLE_FREE
 509	bool
 510
 511config MMU_GATHER_RCU_TABLE_FREE
 512	bool
 513	select MMU_GATHER_TABLE_FREE
 514
 515config MMU_GATHER_PAGE_SIZE
 516	bool
 517
 518config MMU_GATHER_NO_RANGE
 519	bool
 520	select MMU_GATHER_MERGE_VMAS
 521
 522config MMU_GATHER_NO_FLUSH_CACHE
 523	bool
 524
 525config MMU_GATHER_MERGE_VMAS
 526	bool
 527
 528config MMU_GATHER_NO_GATHER
 529	bool
 530	depends on MMU_GATHER_TABLE_FREE
 531
 532config ARCH_WANT_IRQS_OFF_ACTIVATE_MM
 533	bool
 534	help
 535	  Temporary select until all architectures can be converted to have
 536	  irqs disabled over activate_mm. Architectures that do IPI based TLB
 537	  shootdowns should enable this.
 538
 539# Use normal mm refcounting for MMU_LAZY_TLB kernel thread references.
 540# MMU_LAZY_TLB_REFCOUNT=n can improve the scalability of context switching
 541# to/from kernel threads when the same mm is running on a lot of CPUs (a large
 542# multi-threaded application), by reducing contention on the mm refcount.
 543#
 544# This can be disabled if the architecture ensures no CPUs are using an mm as a
 545# "lazy tlb" beyond its final refcount (i.e., by the time __mmdrop frees the mm
 546# or its kernel page tables). This could be arranged by arch_exit_mmap(), or
 547# final exit(2) TLB flush, for example.
 548#
 549# To implement this, an arch *must*:
 550# Ensure the _lazy_tlb variants of mmgrab/mmdrop are used when manipulating
 551# the lazy tlb reference of a kthread's ->active_mm (non-arch code has been
 552# converted already).
 553config MMU_LAZY_TLB_REFCOUNT
 554	def_bool y
 555	depends on !MMU_LAZY_TLB_SHOOTDOWN
 556
 557# This option allows MMU_LAZY_TLB_REFCOUNT=n. It ensures no CPUs are using an
 558# mm as a lazy tlb beyond its last reference count, by shooting down these
 559# users before the mm is deallocated. __mmdrop() first IPIs all CPUs that may
 560# be using the mm as a lazy tlb, so that they may switch themselves to using
 561# init_mm for their active mm. mm_cpumask(mm) is used to determine which CPUs
 562# may be using mm as a lazy tlb mm.
 563#
 564# To implement this, an arch *must*:
 565# - At the time of the final mmdrop of the mm, ensure mm_cpumask(mm) contains
 566#   at least all possible CPUs in which the mm is lazy.
 567# - It must meet the requirements for MMU_LAZY_TLB_REFCOUNT=n (see above).
 568config MMU_LAZY_TLB_SHOOTDOWN
 569	bool
 570
 571config ARCH_HAVE_NMI_SAFE_CMPXCHG
 572	bool
 573
 574config ARCH_HAVE_EXTRA_ELF_NOTES
 575	bool
 576	help
 577	  An architecture should select this in order to enable adding an
 578	  arch-specific ELF note section to core files. It must provide two
 579	  functions: elf_coredump_extra_notes_size() and
 580	  elf_coredump_extra_notes_write() which are invoked by the ELF core
 581	  dumper.
 582
 583config ARCH_HAS_NMI_SAFE_THIS_CPU_OPS
 584	bool
 585
 586config HAVE_ALIGNED_STRUCT_PAGE
 587	bool
 588	help
 589	  This makes sure that struct pages are double word aligned and that
 590	  e.g. the SLUB allocator can perform double word atomic operations
 591	  on a struct page for better performance. However selecting this
 592	  might increase the size of a struct page by a word.
 593
 594config HAVE_CMPXCHG_LOCAL
 595	bool
 596
 597config HAVE_CMPXCHG_DOUBLE
 598	bool
 599
 600config ARCH_WEAK_RELEASE_ACQUIRE
 601	bool
 602
 603config ARCH_WANT_IPC_PARSE_VERSION
 604	bool
 605
 606config ARCH_WANT_COMPAT_IPC_PARSE_VERSION
 607	bool
 608
 609config ARCH_WANT_OLD_COMPAT_IPC
 610	select ARCH_WANT_COMPAT_IPC_PARSE_VERSION
 611	bool
 612
 613config HAVE_ARCH_SECCOMP
 614	bool
 615	help
 616	  An arch should select this symbol to support seccomp mode 1 (the fixed
 617	  syscall policy), and must provide an overrides for __NR_seccomp_sigreturn,
 618	  and compat syscalls if the asm-generic/seccomp.h defaults need adjustment:
 619	  - __NR_seccomp_read_32
 620	  - __NR_seccomp_write_32
 621	  - __NR_seccomp_exit_32
 622	  - __NR_seccomp_sigreturn_32
 623
 624config HAVE_ARCH_SECCOMP_FILTER
 625	bool
 626	select HAVE_ARCH_SECCOMP
 627	help
 628	  An arch should select this symbol if it provides all of these things:
 629	  - all the requirements for HAVE_ARCH_SECCOMP
 630	  - syscall_get_arch()
 631	  - syscall_get_arguments()
 632	  - syscall_rollback()
 633	  - syscall_set_return_value()
 634	  - SIGSYS siginfo_t support
 635	  - secure_computing is called from a ptrace_event()-safe context
 636	  - secure_computing return value is checked and a return value of -1
 637	    results in the system call being skipped immediately.
 638	  - seccomp syscall wired up
 639	  - if !HAVE_SPARSE_SYSCALL_NR, have SECCOMP_ARCH_NATIVE,
 640	    SECCOMP_ARCH_NATIVE_NR, SECCOMP_ARCH_NATIVE_NAME defined. If
 641	    COMPAT is supported, have the SECCOMP_ARCH_COMPAT* defines too.
 642
 643config SECCOMP
 644	prompt "Enable seccomp to safely execute untrusted bytecode"
 645	def_bool y
 646	depends on HAVE_ARCH_SECCOMP
 647	help
 648	  This kernel feature is useful for number crunching applications
 649	  that may need to handle untrusted bytecode during their
 650	  execution. By using pipes or other transports made available
 651	  to the process as file descriptors supporting the read/write
 652	  syscalls, it's possible to isolate those applications in their
 653	  own address space using seccomp. Once seccomp is enabled via
 654	  prctl(PR_SET_SECCOMP) or the seccomp() syscall, it cannot be
 655	  disabled and the task is only allowed to execute a few safe
 656	  syscalls defined by each seccomp mode.
 657
 658	  If unsure, say Y.
 659
 660config SECCOMP_FILTER
 661	def_bool y
 662	depends on HAVE_ARCH_SECCOMP_FILTER && SECCOMP && NET
 663	help
 664	  Enable tasks to build secure computing environments defined
 665	  in terms of Berkeley Packet Filter programs which implement
 666	  task-defined system call filtering polices.
 667
 668	  See Documentation/userspace-api/seccomp_filter.rst for details.
 669
 670config SECCOMP_CACHE_DEBUG
 671	bool "Show seccomp filter cache status in /proc/pid/seccomp_cache"
 672	depends on SECCOMP_FILTER && !HAVE_SPARSE_SYSCALL_NR
 673	depends on PROC_FS
 674	help
 675	  This enables the /proc/pid/seccomp_cache interface to monitor
 676	  seccomp cache data. The file format is subject to change. Reading
 677	  the file requires CAP_SYS_ADMIN.
 678
 679	  This option is for debugging only. Enabling presents the risk that
 680	  an adversary may be able to infer the seccomp filter logic.
 681
 682	  If unsure, say N.
 683
 684config HAVE_ARCH_KSTACK_ERASE
 685	bool
 686	help
 687	  An architecture should select this if it has the code which
 688	  fills the used part of the kernel stack with the KSTACK_ERASE_POISON
 689	  value before returning from system calls.
 690
 691config HAVE_STACKPROTECTOR
 692	bool
 693	help
 694	  An arch should select this symbol if:
 695	  - it has implemented a stack canary (e.g. __stack_chk_guard)
 696
 697config STACKPROTECTOR
 698	bool "Stack Protector buffer overflow detection"
 699	depends on HAVE_STACKPROTECTOR
 700	depends on $(cc-option,-fstack-protector)
 701	default y
 702	help
 703	  This option turns on the "stack-protector" GCC feature. This
 704	  feature puts, at the beginning of functions, a canary value on
 705	  the stack just before the return address, and validates
 706	  the value just before actually returning.  Stack based buffer
 707	  overflows (that need to overwrite this return address) now also
 708	  overwrite the canary, which gets detected and the attack is then
 709	  neutralized via a kernel panic.
 710
 711	  Functions will have the stack-protector canary logic added if they
 712	  have an 8-byte or larger character array on the stack.
 713
 714	  This feature requires gcc version 4.2 or above, or a distribution
 715	  gcc with the feature backported ("-fstack-protector").
 716
 717	  On an x86 "defconfig" build, this feature adds canary checks to
 718	  about 3% of all kernel functions, which increases kernel code size
 719	  by about 0.3%.
 720
 721config STACKPROTECTOR_STRONG
 722	bool "Strong Stack Protector"
 723	depends on STACKPROTECTOR
 724	depends on $(cc-option,-fstack-protector-strong)
 725	default y
 726	help
 727	  Functions will have the stack-protector canary logic added in any
 728	  of the following conditions:
 729
 730	  - local variable's address used as part of the right hand side of an
 731	    assignment or function argument
 732	  - local variable is an array (or union containing an array),
 733	    regardless of array type or length
 734	  - uses register local variables
 735
 736	  This feature requires gcc version 4.9 or above, or a distribution
 737	  gcc with the feature backported ("-fstack-protector-strong").
 738
 739	  On an x86 "defconfig" build, this feature adds canary checks to
 740	  about 20% of all kernel functions, which increases the kernel code
 741	  size by about 2%.
 742
 743config ARCH_SUPPORTS_SHADOW_CALL_STACK
 744	bool
 745	help
 746	  An architecture should select this if it supports the compiler's
 747	  Shadow Call Stack and implements runtime support for shadow stack
 748	  switching.
 749
 750config SHADOW_CALL_STACK
 751	bool "Shadow Call Stack"
 752	depends on ARCH_SUPPORTS_SHADOW_CALL_STACK
 753	depends on DYNAMIC_FTRACE_WITH_ARGS || DYNAMIC_FTRACE_WITH_REGS || !FUNCTION_GRAPH_TRACER
 754	depends on MMU
 755	help
 756	  This option enables the compiler's Shadow Call Stack, which
 757	  uses a shadow stack to protect function return addresses from
 758	  being overwritten by an attacker. More information can be found
 759	  in the compiler's documentation:
 760
 761	  - Clang: https://clang.llvm.org/docs/ShadowCallStack.html
 762	  - GCC: https://gcc.gnu.org/onlinedocs/gcc/Instrumentation-Options.html#Instrumentation-Options
 763
 764	  Note that security guarantees in the kernel differ from the
 765	  ones documented for user space. The kernel must store addresses
 766	  of shadow stacks in memory, which means an attacker capable of
 767	  reading and writing arbitrary memory may be able to locate them
 768	  and hijack control flow by modifying the stacks.
 769
 770config DYNAMIC_SCS
 771	bool
 772	help
 773	  Set by the arch code if it relies on code patching to insert the
 774	  shadow call stack push and pop instructions rather than on the
 775	  compiler.
 776
 777config LTO
 778	bool
 779	help
 780	  Selected if the kernel will be built using the compiler's LTO feature.
 781
 782config LTO_CLANG
 783	bool
 784	select LTO
 785	help
 786	  Selected if the kernel will be built using Clang's LTO feature.
 787
 788config ARCH_SUPPORTS_LTO_CLANG
 789	bool
 790	help
 791	  An architecture should select this option if it supports:
 792	  - compiling with Clang,
 793	  - compiling inline assembly with Clang's integrated assembler,
 794	  - and linking with LLD.
 795
 796config ARCH_SUPPORTS_LTO_CLANG_THIN
 797	bool
 798	help
 799	  An architecture should select this option if it can support Clang's
 800	  ThinLTO mode.
 801
 802config HAS_LTO_CLANG
 803	def_bool y
 804	depends on CC_IS_CLANG && LD_IS_LLD && AS_IS_LLVM
 805	depends on $(success,$(NM) --help | head -n 1 | grep -qi llvm)
 806	depends on $(success,$(AR) --help | head -n 1 | grep -qi llvm)
 807	depends on ARCH_SUPPORTS_LTO_CLANG
 808	depends on !FTRACE_MCOUNT_USE_RECORDMCOUNT
 809	# https://github.com/ClangBuiltLinux/linux/issues/1721
 810	depends on (!KASAN || KASAN_HW_TAGS || CLANG_VERSION >= 170000) || !DEBUG_INFO
 811	depends on (!KCOV || CLANG_VERSION >= 170000) || !DEBUG_INFO
 812	depends on !GCOV_KERNEL
 813	help
 814	  The compiler and Kconfig options support building with Clang's
 815	  LTO.
 816
 817choice
 818	prompt "Link Time Optimization (LTO)"
 819	default LTO_NONE
 820	help
 821	  This option enables Link Time Optimization (LTO), which allows the
 822	  compiler to optimize binaries globally.
 823
 824	  If unsure, select LTO_NONE. Note that LTO is very resource-intensive
 825	  so it's disabled by default.
 826
 827config LTO_NONE
 828	bool "None"
 829	help
 830	  Build the kernel normally, without Link Time Optimization (LTO).
 831
 832config LTO_CLANG_FULL
 833	bool "Clang Full LTO (EXPERIMENTAL)"
 834	depends on HAS_LTO_CLANG
 835	depends on !COMPILE_TEST
 836	select LTO_CLANG
 837	help
 838	  This option enables Clang's full Link Time Optimization (LTO), which
 839	  allows the compiler to optimize the kernel globally. If you enable
 840	  this option, the compiler generates LLVM bitcode instead of ELF
 841	  object files, and the actual compilation from bitcode happens at
 842	  the LTO link step, which may take several minutes depending on the
 843	  kernel configuration. More information can be found from LLVM's
 844	  documentation:
 845
 846	    https://llvm.org/docs/LinkTimeOptimization.html
 847
 848	  During link time, this option can use a large amount of RAM, and
 849	  may take much longer than the ThinLTO option.
 850
 851config LTO_CLANG_THIN
 852	bool "Clang ThinLTO (EXPERIMENTAL)"
 853	depends on HAS_LTO_CLANG && ARCH_SUPPORTS_LTO_CLANG_THIN
 854	select LTO_CLANG
 855	help
 856	  This option enables Clang's ThinLTO, which allows for parallel
 857	  optimization and faster incremental compiles compared to the
 858	  CONFIG_LTO_CLANG_FULL option. More information can be found
 859	  from Clang's documentation:
 860
 861	    https://clang.llvm.org/docs/ThinLTO.html
 862
 863	  If unsure, say Y.
 864endchoice
 865
 866config ARCH_SUPPORTS_AUTOFDO_CLANG
 867	bool
 868
 869config AUTOFDO_CLANG
 870	bool "Enable Clang's AutoFDO build (EXPERIMENTAL)"
 871	depends on ARCH_SUPPORTS_AUTOFDO_CLANG
 872	depends on CC_IS_CLANG && CLANG_VERSION >= 170000
 873	help
 874	  This option enables Clang’s AutoFDO build. When
 875	  an AutoFDO profile is specified in variable
 876	  CLANG_AUTOFDO_PROFILE during the build process,
 877	  Clang uses the profile to optimize the kernel.
 878
 879	  If no profile is specified, AutoFDO options are
 880	  still passed to Clang to facilitate the collection
 881	  of perf data for creating an AutoFDO profile in
 882	  subsequent builds.
 883
 884	  If unsure, say N.
 885
 886config ARCH_SUPPORTS_PROPELLER_CLANG
 887	bool
 888
 889config PROPELLER_CLANG
 890	bool "Enable Clang's Propeller build"
 891	depends on ARCH_SUPPORTS_PROPELLER_CLANG
 892	depends on CC_IS_CLANG && CLANG_VERSION >= 190000
 893	help
 894	  This option enables Clang’s Propeller build. When the Propeller
 895	  profiles is specified in variable CLANG_PROPELLER_PROFILE_PREFIX
 896	  during the build process, Clang uses the profiles to optimize
 897	  the kernel.
 898
 899	  If no profile is specified, Propeller options are still passed
 900	  to Clang to facilitate the collection of perf data for creating
 901	  the Propeller profiles in subsequent builds.
 902
 903	  If unsure, say N.
 904
 905config ARCH_SUPPORTS_CFI
 906	bool
 907	help
 908	  An architecture should select this option if it can support Kernel
 909	  Control-Flow Integrity (CFI) checking (-fsanitize=kcfi).
 910
 911config ARCH_USES_CFI_TRAPS
 912	bool
 913	help
 914	  An architecture should select this option if it requires the
 915	  .kcfi_traps section for KCFI trap handling.
 916
 917config ARCH_USES_CFI_GENERIC_LLVM_PASS
 918	bool
 919	help
 920	  An architecture should select this option if it uses the generic
 921	  KCFIPass in LLVM to expand kCFI bundles instead of architecture-specific
 922	  lowering.
 923
 924config CFI
 925	bool "Use Kernel Control Flow Integrity (kCFI)"
 926	default CFI_CLANG
 927	depends on ARCH_SUPPORTS_CFI
 928	depends on $(cc-option,-fsanitize=kcfi)
 929	help
 930	  This option enables forward-edge Control Flow Integrity (CFI)
 931	  checking, where the compiler injects a runtime check to each
 932	  indirect function call to ensure the target is a valid function with
 933	  the correct static type. This restricts possible call targets and
 934	  makes it more difficult for an attacker to exploit bugs that allow
 935	  the modification of stored function pointers. More information can be
 936	  found from Clang's documentation:
 937
 938	    https://clang.llvm.org/docs/ControlFlowIntegrity.html
 939
 940config CFI_CLANG
 941	bool
 942	transitional
 943	help
 944	  Transitional config for CFI_CLANG to CFI migration.
 945
 946config CFI_ICALL_NORMALIZE_INTEGERS
 947	bool "Normalize CFI tags for integers"
 948	depends on CFI
 949	depends on HAVE_CFI_ICALL_NORMALIZE_INTEGERS
 950	help
 951	  This option normalizes the CFI tags for integer types so that all
 952	  integer types of the same size and signedness receive the same CFI
 953	  tag.
 954
 955	  The option is separate from CONFIG_RUST because it affects the ABI.
 956	  When working with build systems that care about the ABI, it is
 957	  convenient to be able to turn on this flag first, before Rust is
 958	  turned on.
 959
 960	  This option is necessary for using CFI with Rust. If unsure, say N.
 961
 962config HAVE_CFI_ICALL_NORMALIZE_INTEGERS
 963	def_bool y
 964	depends on $(cc-option,-fsanitize=kcfi -fsanitize-cfi-icall-experimental-normalize-integers)
 965	# With GCOV/KASAN we need this fix: https://github.com/llvm/llvm-project/pull/104826
 966	depends on CLANG_VERSION >= 190103 || (!GCOV_KERNEL && !KASAN_GENERIC && !KASAN_SW_TAGS)
 967
 968config HAVE_CFI_ICALL_NORMALIZE_INTEGERS_RUSTC
 969	def_bool y
 970	depends on HAVE_CFI_ICALL_NORMALIZE_INTEGERS
 971	depends on RUSTC_VERSION >= 107900
 972	depends on ARM64 || X86_64
 973	# With GCOV/KASAN we need this fix: https://github.com/rust-lang/rust/pull/129373
 974	depends on (RUSTC_LLVM_VERSION >= 190103 && RUSTC_VERSION >= 108200) || \
 975		(!GCOV_KERNEL && !KASAN_GENERIC && !KASAN_SW_TAGS)
 976
 977config CFI_PERMISSIVE
 978	bool "Use CFI in permissive mode"
 979	depends on CFI
 980	help
 981	  When selected, Control Flow Integrity (CFI) violations result in a
 982	  warning instead of a kernel panic. This option should only be used
 983	  for finding indirect call type mismatches during development.
 984
 985	  If unsure, say N.
 986
 987config HAVE_ARCH_WITHIN_STACK_FRAMES
 988	bool
 989	help
 990	  An architecture should select this if it can walk the kernel stack
 991	  frames to determine if an object is part of either the arguments
 992	  or local variables (i.e. that it excludes saved return addresses,
 993	  and similar) by implementing an inline arch_within_stack_frames(),
 994	  which is used by CONFIG_HARDENED_USERCOPY.
 995
 996config HAVE_CONTEXT_TRACKING_USER
 997	bool
 998	help
 999	  Provide kernel/user boundaries probes necessary for subsystems
1000	  that need it, such as userspace RCU extended quiescent state.
1001	  Syscalls need to be wrapped inside user_exit()-user_enter(), either
1002	  optimized behind static key or through the slow path using TIF_NOHZ
1003	  flag. Exceptions handlers must be wrapped as well. Irqs are already
1004	  protected inside ct_irq_enter/ct_irq_exit() but preemption or signal
1005	  handling on irq exit still need to be protected.
1006
1007config HAVE_CONTEXT_TRACKING_USER_OFFSTACK
1008	bool
1009	help
1010	  Architecture neither relies on exception_enter()/exception_exit()
1011	  nor on schedule_user(). Also preempt_schedule_notrace() and
1012	  preempt_schedule_irq() can't be called in a preemptible section
1013	  while context tracking is CT_STATE_USER. This feature reflects a sane
1014	  entry implementation where the following requirements are met on
1015	  critical entry code, ie: before user_exit() or after user_enter():
1016
1017	  - Critical entry code isn't preemptible (or better yet:
1018	    not interruptible).
1019	  - No use of RCU read side critical sections, unless ct_nmi_enter()
1020	    got called.
1021	  - No use of instrumentation, unless instrumentation_begin() got
1022	    called.
1023
1024config HAVE_TIF_NOHZ
1025	bool
1026	help
1027	  Arch relies on TIF_NOHZ and syscall slow path to implement context
1028	  tracking calls to user_enter()/user_exit().
1029
1030config HAVE_VIRT_CPU_ACCOUNTING
1031	bool
1032
1033config HAVE_VIRT_CPU_ACCOUNTING_IDLE
1034	bool
1035	help
1036	  Architecture has its own way to account idle CPU time and therefore
1037	  doesn't implement vtime_account_idle().
1038
1039config ARCH_HAS_SCALED_CPUTIME
1040	bool
1041
1042config HAVE_VIRT_CPU_ACCOUNTING_GEN
1043	bool
1044	default y if 64BIT
1045	help
1046	  With VIRT_CPU_ACCOUNTING_GEN, cputime_t becomes 64-bit.
1047	  Before enabling this option, arch code must be audited
1048	  to ensure there are no races in concurrent read/write of
1049	  cputime_t. For example, reading/writing 64-bit cputime_t on
1050	  some 32-bit arches may require multiple accesses, so proper
1051	  locking is needed to protect against concurrent accesses.
1052
1053config HAVE_IRQ_TIME_ACCOUNTING
1054	bool
1055	help
1056	  Archs need to ensure they use a high enough resolution clock to
1057	  support irq time accounting and then call enable_sched_clock_irqtime().
1058
1059config HAVE_MOVE_PUD
1060	bool
1061	help
1062	  Architectures that select this are able to move page tables at the
1063	  PUD level. If there are only 3 page table levels, the move effectively
1064	  happens at the PGD level.
1065
1066config HAVE_MOVE_PMD
1067	bool
1068	help
1069	  Archs that select this are able to move page tables at the PMD level.
1070
1071config HAVE_ARCH_TRANSPARENT_HUGEPAGE
1072	bool
1073
1074config HAVE_ARCH_TRANSPARENT_HUGEPAGE_PUD
1075	bool
1076
1077config HAVE_ARCH_HUGE_VMAP
1078	bool
1079
1080#
1081#  Archs that select this would be capable of PMD-sized vmaps (i.e.,
1082#  arch_vmap_pmd_supported() returns true). The VM_ALLOW_HUGE_VMAP flag
1083#  must be used to enable allocations to use hugepages.
1084#
1085config HAVE_ARCH_HUGE_VMALLOC
1086	depends on HAVE_ARCH_HUGE_VMAP
1087	bool
1088
1089config ARCH_WANT_HUGE_PMD_SHARE
1090	bool
1091
1092# Archs that want to use pmd_mkwrite on kernel memory need it defined even
1093# if there are no userspace memory management features that use it
1094config ARCH_WANT_KERNEL_PMD_MKWRITE
1095	bool
1096
1097config ARCH_WANT_PMD_MKWRITE
1098	def_bool TRANSPARENT_HUGEPAGE || ARCH_WANT_KERNEL_PMD_MKWRITE
1099
1100config HAVE_ARCH_SOFT_DIRTY
1101	bool
1102
1103config HAVE_MOD_ARCH_SPECIFIC
1104	bool
1105	help
1106	  The arch uses struct mod_arch_specific to store data.  Many arches
1107	  just need a simple module loader without arch specific data - those
1108	  should not enable this.
1109
1110config MODULES_USE_ELF_RELA
1111	bool
1112	help
1113	  Modules only use ELF RELA relocations.  Modules with ELF REL
1114	  relocations will give an error.
1115
1116config MODULES_USE_ELF_REL
1117	bool
1118	help
1119	  Modules only use ELF REL relocations.  Modules with ELF RELA
1120	  relocations will give an error.
1121
1122config ARCH_WANTS_MODULES_DATA_IN_VMALLOC
1123	bool
1124	help
1125	  For architectures like powerpc/32 which have constraints on module
1126	  allocation and need to allocate module data outside of module area.
1127
1128config ARCH_WANTS_EXECMEM_LATE
1129	bool
1130	help
1131	  For architectures that do not allocate executable memory early on
1132	  boot, but rather require its initialization late when there is
1133	  enough entropy for module space randomization, for instance
1134	  arm64.
1135
1136config ARCH_HAS_EXECMEM_ROX
1137	bool
1138	depends on MMU && !HIGHMEM
1139	help
1140	  For architectures that support allocations of executable memory
1141	  with read-only execute permissions. Architecture must implement
1142	  execmem_fill_trapping_insns() callback to enable this.
1143
1144config HAVE_IRQ_EXIT_ON_IRQ_STACK
1145	bool
1146	help
1147	  Architecture doesn't only execute the irq handler on the irq stack
1148	  but also irq_exit(). This way we can process softirqs on this irq
1149	  stack instead of switching to a new one when we call __do_softirq()
1150	  in the end of an hardirq.
1151	  This spares a stack switch and improves cache usage on softirq
1152	  processing.
1153
1154config HAVE_SOFTIRQ_ON_OWN_STACK
1155	bool
1156	help
1157	  Architecture provides a function to run __do_softirq() on a
1158	  separate stack.
1159
1160config SOFTIRQ_ON_OWN_STACK
1161	def_bool HAVE_SOFTIRQ_ON_OWN_STACK && !PREEMPT_RT
1162
1163config ALTERNATE_USER_ADDRESS_SPACE
1164	bool
1165	help
1166	  Architectures set this when the CPU uses separate address
1167	  spaces for kernel and user space pointers. In this case, the
1168	  access_ok() check on a __user pointer is skipped.
1169
1170config PGTABLE_LEVELS
1171	int
1172	default 2
1173
1174config ARCH_HAS_ELF_RANDOMIZE
1175	bool
1176	help
1177	  An architecture supports choosing randomized locations for
1178	  stack, mmap, brk, and ET_DYN. Defined functions:
1179	  - arch_mmap_rnd()
1180	  - arch_randomize_brk()
1181
1182config HAVE_ARCH_MMAP_RND_BITS
1183	bool
1184	help
1185	  An arch should select this symbol if it supports setting a variable
1186	  number of bits for use in establishing the base address for mmap
1187	  allocations, has MMU enabled and provides values for both:
1188	  - ARCH_MMAP_RND_BITS_MIN
1189	  - ARCH_MMAP_RND_BITS_MAX
1190
1191config HAVE_EXIT_THREAD
1192	bool
1193	help
1194	  An architecture implements exit_thread.
1195
1196config ARCH_MMAP_RND_BITS_MIN
1197	int
1198
1199config ARCH_MMAP_RND_BITS_MAX
1200	int
1201
1202config ARCH_MMAP_RND_BITS_DEFAULT
1203	int
1204
1205config ARCH_MMAP_RND_BITS
1206	int "Number of bits to use for ASLR of mmap base address" if EXPERT
1207	range ARCH_MMAP_RND_BITS_MIN ARCH_MMAP_RND_BITS_MAX
1208	default ARCH_MMAP_RND_BITS_DEFAULT if ARCH_MMAP_RND_BITS_DEFAULT
1209	default ARCH_MMAP_RND_BITS_MIN
1210	depends on HAVE_ARCH_MMAP_RND_BITS
1211	help
1212	  This value can be used to select the number of bits to use to
1213	  determine the random offset to the base address of vma regions
1214	  resulting from mmap allocations. This value will be bounded
1215	  by the architecture's minimum and maximum supported values.
1216
1217	  This value can be changed after boot using the
1218	  /proc/sys/vm/mmap_rnd_bits tunable
1219
1220config HAVE_ARCH_MMAP_RND_COMPAT_BITS
1221	bool
1222	help
1223	  An arch should select this symbol if it supports running applications
1224	  in compatibility mode, supports setting a variable number of bits for
1225	  use in establishing the base address for mmap allocations, has MMU
1226	  enabled and provides values for both:
1227	  - ARCH_MMAP_RND_COMPAT_BITS_MIN
1228	  - ARCH_MMAP_RND_COMPAT_BITS_MAX
1229
1230config ARCH_MMAP_RND_COMPAT_BITS_MIN
1231	int
1232
1233config ARCH_MMAP_RND_COMPAT_BITS_MAX
1234	int
1235
1236config ARCH_MMAP_RND_COMPAT_BITS_DEFAULT
1237	int
1238
1239config ARCH_MMAP_RND_COMPAT_BITS
1240	int "Number of bits to use for ASLR of mmap base address for compatible applications" if EXPERT
1241	range ARCH_MMAP_RND_COMPAT_BITS_MIN ARCH_MMAP_RND_COMPAT_BITS_MAX
1242	default ARCH_MMAP_RND_COMPAT_BITS_DEFAULT if ARCH_MMAP_RND_COMPAT_BITS_DEFAULT
1243	default ARCH_MMAP_RND_COMPAT_BITS_MIN
1244	depends on HAVE_ARCH_MMAP_RND_COMPAT_BITS
1245	help
1246	  This value can be used to select the number of bits to use to
1247	  determine the random offset to the base address of vma regions
1248	  resulting from mmap allocations for compatible applications This
1249	  value will be bounded by the architecture's minimum and maximum
1250	  supported values.
1251
1252	  This value can be changed after boot using the
1253	  /proc/sys/vm/mmap_rnd_compat_bits tunable
1254
1255config HAVE_ARCH_COMPAT_MMAP_BASES
1256	bool
1257	help
1258	  This allows 64bit applications to invoke 32-bit mmap() syscall
1259	  and vice-versa 32-bit applications to call 64-bit mmap().
1260	  Required for applications doing different bitness syscalls.
1261
1262config HAVE_PAGE_SIZE_4KB
1263	bool
1264
1265config HAVE_PAGE_SIZE_8KB
1266	bool
1267
1268config HAVE_PAGE_SIZE_16KB
1269	bool
1270
1271config HAVE_PAGE_SIZE_32KB
1272	bool
1273
1274config HAVE_PAGE_SIZE_64KB
1275	bool
1276
1277config HAVE_PAGE_SIZE_256KB
1278	bool
1279
1280choice
1281	prompt "MMU page size"
1282
1283config PAGE_SIZE_4KB
1284	bool "4KiB pages"
1285	depends on HAVE_PAGE_SIZE_4KB
1286	help
1287	  This option select the standard 4KiB Linux page size and the only
1288	  available option on many architectures. Using 4KiB page size will
1289	  minimize memory consumption and is therefore recommended for low
1290	  memory systems.
1291	  Some software that is written for x86 systems makes incorrect
1292	  assumptions about the page size and only runs on 4KiB pages.
1293
1294config PAGE_SIZE_8KB
1295	bool "8KiB pages"
1296	depends on HAVE_PAGE_SIZE_8KB
1297	help
1298	  This option is the only supported page size on a few older
1299	  processors, and can be slightly faster than 4KiB pages.
1300
1301config PAGE_SIZE_16KB
1302	bool "16KiB pages"
1303	depends on HAVE_PAGE_SIZE_16KB
1304	help
1305	  This option is usually a good compromise between memory
1306	  consumption and performance for typical desktop and server
1307	  workloads, often saving a level of page table lookups compared
1308	  to 4KB pages as well as reducing TLB pressure and overhead of
1309	  per-page operations in the kernel at the expense of a larger
1310	  page cache.
1311
1312config PAGE_SIZE_32KB
1313	bool "32KiB pages"
1314	depends on HAVE_PAGE_SIZE_32KB
1315	help
1316	  Using 32KiB page size will result in slightly higher performance
1317	  kernel at the price of higher memory consumption compared to
1318	  16KiB pages.	This option is available only on cnMIPS cores.
1319	  Note that you will need a suitable Linux distribution to
1320	  support this.
1321
1322config PAGE_SIZE_64KB
1323	bool "64KiB pages"
1324	depends on HAVE_PAGE_SIZE_64KB
1325	help
1326	  Using 64KiB page size will result in slightly higher performance
1327	  kernel at the price of much higher memory consumption compared to
1328	  4KiB or 16KiB pages.
1329	  This is not suitable for general-purpose workloads but the
1330	  better performance may be worth the cost for certain types of
1331	  supercomputing or database applications that work mostly with
1332	  large in-memory data rather than small files.
1333
1334config PAGE_SIZE_256KB
1335	bool "256KiB pages"
1336	depends on HAVE_PAGE_SIZE_256KB
1337	help
1338	  256KiB pages have little practical value due to their extreme
1339	  memory usage.  The kernel will only be able to run applications
1340	  that have been compiled with '-zmax-page-size' set to 256KiB
1341	  (the default is 64KiB or 4KiB on most architectures).
1342
1343endchoice
1344
1345config PAGE_SIZE_LESS_THAN_64KB
1346	def_bool y
1347	depends on !PAGE_SIZE_64KB
1348	depends on PAGE_SIZE_LESS_THAN_256KB
1349
1350config PAGE_SIZE_LESS_THAN_256KB
1351	def_bool y
1352	depends on !PAGE_SIZE_256KB
1353
1354config PAGE_SHIFT
1355	int
1356	default	12 if PAGE_SIZE_4KB
1357	default	13 if PAGE_SIZE_8KB
1358	default	14 if PAGE_SIZE_16KB
1359	default	15 if PAGE_SIZE_32KB
1360	default	16 if PAGE_SIZE_64KB
1361	default	18 if PAGE_SIZE_256KB
1362
1363# This allows to use a set of generic functions to determine mmap base
1364# address by giving priority to top-down scheme only if the process
1365# is not in legacy mode (compat task, unlimited stack size or
1366# sysctl_legacy_va_layout).
1367# Architecture that selects this option can provide its own version of:
1368# - STACK_RND_MASK
1369config ARCH_WANT_DEFAULT_TOPDOWN_MMAP_LAYOUT
1370	bool
1371	depends on MMU
1372	select ARCH_HAS_ELF_RANDOMIZE
1373
1374config HAVE_OBJTOOL
1375	bool
1376
1377config HAVE_JUMP_LABEL_HACK
1378	bool
1379
1380config HAVE_NOINSTR_HACK
1381	bool
1382
1383config HAVE_NOINSTR_VALIDATION
1384	bool
1385
1386config HAVE_UACCESS_VALIDATION
1387	bool
1388	select OBJTOOL
1389
1390config HAVE_STACK_VALIDATION
1391	bool
1392	help
1393	  Architecture supports objtool compile-time frame pointer rule
1394	  validation.
1395
1396config HAVE_RELIABLE_STACKTRACE
1397	bool
1398	help
1399	  Architecture has either save_stack_trace_tsk_reliable() or
1400	  arch_stack_walk_reliable() function which only returns a stack trace
1401	  if it can guarantee the trace is reliable.
1402
1403config HAVE_ARCH_HASH
1404	bool
1405	default n
1406	help
1407	  If this is set, the architecture provides an <asm/hash.h>
1408	  file which provides platform-specific implementations of some
1409	  functions in <linux/hash.h> or fs/namei.c.
1410
1411config HAVE_ARCH_NVRAM_OPS
1412	bool
1413
1414config ISA_BUS_API
1415	def_bool ISA
1416
1417#
1418# ABI hall of shame
1419#
1420config CLONE_BACKWARDS
1421	bool
1422	help
1423	  Architecture has tls passed as the 4th argument of clone(2),
1424	  not the 5th one.
1425
1426config CLONE_BACKWARDS2
1427	bool
1428	help
1429	  Architecture has the first two arguments of clone(2) swapped.
1430
1431config CLONE_BACKWARDS3
1432	bool
1433	help
1434	  Architecture has tls passed as the 3rd argument of clone(2),
1435	  not the 5th one.
1436
1437config ODD_RT_SIGACTION
1438	bool
1439	help
1440	  Architecture has unusual rt_sigaction(2) arguments
1441
1442config OLD_SIGSUSPEND
1443	bool
1444	help
1445	  Architecture has old sigsuspend(2) syscall, of one-argument variety
1446
1447config OLD_SIGSUSPEND3
1448	bool
1449	help
1450	  Even weirder antique ABI - three-argument sigsuspend(2)
1451
1452config OLD_SIGACTION
1453	bool
1454	help
1455	  Architecture has old sigaction(2) syscall.  Nope, not the same
1456	  as OLD_SIGSUSPEND | OLD_SIGSUSPEND3 - alpha has sigsuspend(2),
1457	  but fairly different variant of sigaction(2), thanks to OSF/1
1458	  compatibility...
1459
1460config COMPAT_OLD_SIGACTION
1461	bool
1462
1463config COMPAT_32BIT_TIME
1464	bool "Provide system calls for 32-bit time_t"
1465	default !64BIT || COMPAT
1466	help
1467	  This enables 32 bit time_t support in addition to 64 bit time_t support.
1468	  This is relevant on all 32-bit architectures, and 64-bit architectures
1469	  as part of compat syscall handling.
1470
1471config ARCH_NO_PREEMPT
1472	bool
1473
1474config ARCH_SUPPORTS_RT
1475	bool
1476
1477config CPU_NO_EFFICIENT_FFS
1478	def_bool n
1479
1480config HAVE_ARCH_VMAP_STACK
1481	def_bool n
1482	help
1483	  An arch should select this symbol if it can support kernel stacks
1484	  in vmalloc space.  This means:
1485
1486	  - vmalloc space must be large enough to hold many kernel stacks.
1487	    This may rule out many 32-bit architectures.
1488
1489	  - Stacks in vmalloc space need to work reliably.  For example, if
1490	    vmap page tables are created on demand, either this mechanism
1491	    needs to work while the stack points to a virtual address with
1492	    unpopulated page tables or arch code (switch_to() and switch_mm(),
1493	    most likely) needs to ensure that the stack's page table entries
1494	    are populated before running on a possibly unpopulated stack.
1495
1496	  - If the stack overflows into a guard page, something reasonable
1497	    should happen.  The definition of "reasonable" is flexible, but
1498	    instantly rebooting without logging anything would be unfriendly.
1499
1500config VMAP_STACK
1501	default y
1502	bool "Use a virtually-mapped stack"
1503	depends on HAVE_ARCH_VMAP_STACK
1504	depends on !KASAN || KASAN_HW_TAGS || KASAN_VMALLOC
1505	help
1506	  Enable this if you want the use virtually-mapped kernel stacks
1507	  with guard pages.  This causes kernel stack overflows to be
1508	  caught immediately rather than causing difficult-to-diagnose
1509	  corruption.
1510
1511	  To use this with software KASAN modes, the architecture must support
1512	  backing virtual mappings with real shadow memory, and KASAN_VMALLOC
1513	  must be enabled.
1514
1515config HAVE_ARCH_RANDOMIZE_KSTACK_OFFSET
1516	def_bool n
1517	help
1518	  An arch should select this symbol if it can support kernel stack
1519	  offset randomization with calls to add_random_kstack_offset()
1520	  during syscall entry and choose_random_kstack_offset() during
1521	  syscall exit. Careful removal of -fstack-protector-strong and
1522	  -fstack-protector should also be applied to the entry code and
1523	  closely examined, as the artificial stack bump looks like an array
1524	  to the compiler, so it will attempt to add canary checks regardless
1525	  of the static branch state.
1526
1527config RANDOMIZE_KSTACK_OFFSET
1528	bool "Support for randomizing kernel stack offset on syscall entry" if EXPERT
1529	default y
1530	depends on HAVE_ARCH_RANDOMIZE_KSTACK_OFFSET
1531	help
1532	  The kernel stack offset can be randomized (after pt_regs) by
1533	  roughly 5 bits of entropy, frustrating memory corruption
1534	  attacks that depend on stack address determinism or
1535	  cross-syscall address exposures.
1536
1537	  The feature is controlled via the "randomize_kstack_offset=on/off"
1538	  kernel boot param, and if turned off has zero overhead due to its use
1539	  of static branches (see JUMP_LABEL).
1540
1541	  If unsure, say Y.
1542
1543config RANDOMIZE_KSTACK_OFFSET_DEFAULT
1544	bool "Default state of kernel stack offset randomization"
1545	depends on RANDOMIZE_KSTACK_OFFSET
1546	help
1547	  Kernel stack offset randomization is controlled by kernel boot param
1548	  "randomize_kstack_offset=on/off", and this config chooses the default
1549	  boot state.
1550
1551config ARCH_OPTIONAL_KERNEL_RWX
1552	def_bool n
1553
1554config ARCH_OPTIONAL_KERNEL_RWX_DEFAULT
1555	def_bool n
1556
1557config ARCH_HAS_STRICT_KERNEL_RWX
1558	def_bool n
1559
1560config STRICT_KERNEL_RWX
1561	bool "Make kernel text and rodata read-only" if ARCH_OPTIONAL_KERNEL_RWX
1562	depends on ARCH_HAS_STRICT_KERNEL_RWX
1563	default !ARCH_OPTIONAL_KERNEL_RWX || ARCH_OPTIONAL_KERNEL_RWX_DEFAULT
1564	help
1565	  If this is set, kernel text and rodata memory will be made read-only,
1566	  and non-text memory will be made non-executable. This provides
1567	  protection against certain security exploits (e.g. executing the heap
1568	  or modifying text)
1569
1570	  These features are considered standard security practice these days.
1571	  You should say Y here in almost all cases.
1572
1573config ARCH_HAS_STRICT_MODULE_RWX
1574	def_bool n
1575
1576config STRICT_MODULE_RWX
1577	bool "Set loadable kernel module data as NX and text as RO" if ARCH_OPTIONAL_KERNEL_RWX
1578	depends on ARCH_HAS_STRICT_MODULE_RWX && MODULES
1579	default !ARCH_OPTIONAL_KERNEL_RWX || ARCH_OPTIONAL_KERNEL_RWX_DEFAULT
1580	help
1581	  If this is set, module text and rodata memory will be made read-only,
1582	  and non-text memory will be made non-executable. This provides
1583	  protection against certain security exploits (e.g. writing to text)
1584
1585# select if the architecture provides an asm/dma-direct.h header
1586config ARCH_HAS_PHYS_TO_DMA
1587	bool
1588
1589config ARCH_HAS_CPU_RESCTRL
1590	bool
1591	help
1592	  An architecture selects this option to indicate that the necessary
1593	  hooks are provided to support the common memory system usage
1594	  monitoring and control interfaces provided by the 'resctrl'
1595	  filesystem (see RESCTRL_FS).
1596
1597config HAVE_ARCH_COMPILER_H
1598	bool
1599	help
1600	  An architecture can select this if it provides an
1601	  asm/compiler.h header that should be included after
1602	  linux/compiler-*.h in order to override macro definitions that those
1603	  headers generally provide.
1604
1605config HAVE_ARCH_LIBGCC_H
1606	bool
1607	help
1608	  An architecture can select this if it provides an
1609	  asm/libgcc.h header that should be included after
1610	  linux/libgcc.h in order to override macro definitions that
1611	  header generally provides.
1612
1613config HAVE_ARCH_PREL32_RELOCATIONS
1614	bool
1615	help
1616	  May be selected by an architecture if it supports place-relative
1617	  32-bit relocations, both in the toolchain and in the module loader,
1618	  in which case relative references can be used in special sections
1619	  for PCI fixup, initcalls etc which are only half the size on 64 bit
1620	  architectures, and don't require runtime relocation on relocatable
1621	  kernels.
1622
1623config ARCH_USE_MEMREMAP_PROT
1624	bool
1625
1626config LOCK_EVENT_COUNTS
1627	bool "Locking event counts collection"
1628	depends on DEBUG_FS
1629	help
1630	  Enable light-weight counting of various locking related events
1631	  in the system with minimal performance impact. This reduces
1632	  the chance of application behavior change because of timing
1633	  differences. The counts are reported via debugfs.
1634
1635# Select if the architecture has support for applying RELR relocations.
1636config ARCH_HAS_RELR
1637	bool
1638
1639config RELR
1640	bool "Use RELR relocation packing"
1641	depends on ARCH_HAS_RELR && TOOLS_SUPPORT_RELR
1642	default y
1643	help
1644	  Store the kernel's dynamic relocations in the RELR relocation packing
1645	  format. Requires a compatible linker (LLD supports this feature), as
1646	  well as compatible NM and OBJCOPY utilities (llvm-nm and llvm-objcopy
1647	  are compatible).
1648
1649config ARCH_HAS_MEM_ENCRYPT
1650	bool
1651
1652config ARCH_HAS_CC_PLATFORM
1653	bool
1654
1655config HAVE_SPARSE_SYSCALL_NR
1656	bool
1657	help
1658	  An architecture should select this if its syscall numbering is sparse
1659	  to save space. For example, MIPS architecture has a syscall array with
1660	  entries at 4000, 5000 and 6000 locations. This option turns on syscall
1661	  related optimizations for a given architecture.
1662
1663config ARCH_HAS_VDSO_ARCH_DATA
1664	depends on HAVE_GENERIC_VDSO
1665	bool
1666
1667config ARCH_HAS_VDSO_TIME_DATA
1668	bool
1669
1670config HAVE_STATIC_CALL
1671	bool
1672
1673config HAVE_STATIC_CALL_INLINE
1674	bool
1675	depends on HAVE_STATIC_CALL
1676	select OBJTOOL
1677
1678config HAVE_PREEMPT_DYNAMIC
1679	bool
1680
1681config HAVE_PREEMPT_DYNAMIC_CALL
1682	bool
1683	depends on HAVE_STATIC_CALL
1684	select HAVE_PREEMPT_DYNAMIC
1685	help
1686	  An architecture should select this if it can handle the preemption
1687	  model being selected at boot time using static calls.
1688
1689	  Where an architecture selects HAVE_STATIC_CALL_INLINE, any call to a
1690	  preemption function will be patched directly.
1691
1692	  Where an architecture does not select HAVE_STATIC_CALL_INLINE, any
1693	  call to a preemption function will go through a trampoline, and the
1694	  trampoline will be patched.
1695
1696	  It is strongly advised to support inline static call to avoid any
1697	  overhead.
1698
1699config HAVE_PREEMPT_DYNAMIC_KEY
1700	bool
1701	depends on HAVE_ARCH_JUMP_LABEL
1702	select HAVE_PREEMPT_DYNAMIC
1703	help
1704	  An architecture should select this if it can handle the preemption
1705	  model being selected at boot time using static keys.
1706
1707	  Each preemption function will be given an early return based on a
1708	  static key. This should have slightly lower overhead than non-inline
1709	  static calls, as this effectively inlines each trampoline into the
1710	  start of its callee. This may avoid redundant work, and may
1711	  integrate better with CFI schemes.
1712
1713	  This will have greater overhead than using inline static calls as
1714	  the call to the preemption function cannot be entirely elided.
1715
1716config ARCH_WANT_LD_ORPHAN_WARN
1717	bool
1718	help
1719	  An arch should select this symbol once all linker sections are explicitly
1720	  included, size-asserted, or discarded in the linker scripts. This is
1721	  important because we never want expected sections to be placed heuristically
1722	  by the linker, since the locations of such sections can change between linker
1723	  versions.
1724
1725config HAVE_ARCH_PFN_VALID
1726	bool
1727
1728config ARCH_SUPPORTS_DEBUG_PAGEALLOC
1729	bool
1730
1731config ARCH_SUPPORTS_PAGE_TABLE_CHECK
1732	bool
1733
1734config ARCH_SPLIT_ARG64
1735	bool
1736	help
1737	  If a 32-bit architecture requires 64-bit arguments to be split into
1738	  pairs of 32-bit arguments, select this option.
1739
1740config ARCH_HAS_ELFCORE_COMPAT
1741	bool
1742
1743config ARCH_HAS_PARANOID_L1D_FLUSH
1744	bool
1745
1746config ARCH_HAVE_TRACE_MMIO_ACCESS
1747	bool
1748
1749config DYNAMIC_SIGFRAME
1750	bool
1751
1752# Select, if arch has a named attribute group bound to NUMA device nodes.
1753config HAVE_ARCH_NODE_DEV_GROUP
1754	bool
1755
1756config ARCH_HAS_HW_PTE_YOUNG
1757	bool
1758	help
1759	  Architectures that select this option are capable of setting the
1760	  accessed bit in PTE entries when using them as part of linear address
1761	  translations. Architectures that require runtime check should select
1762	  this option and override arch_has_hw_pte_young().
1763
1764config ARCH_HAS_NONLEAF_PMD_YOUNG
1765	bool
1766	help
1767	  Architectures that select this option are capable of setting the
1768	  accessed bit in non-leaf PMD entries when using them as part of linear
1769	  address translations. Page table walkers that clear the accessed bit
1770	  may use this capability to reduce their search space.
1771
1772config ARCH_HAS_KERNEL_FPU_SUPPORT
1773	bool
1774	help
1775	  Architectures that select this option can run floating-point code in
1776	  the kernel, as described in Documentation/core-api/floating-point.rst.
1777
1778config ARCH_VMLINUX_NEEDS_RELOCS
1779	bool
1780	help
1781	  Whether the architecture needs vmlinux to be built with static
1782	  relocations preserved. This is used by some architectures to
1783	  construct bespoke relocation tables for KASLR.
1784
1785# Select if architecture uses the common generic TIF bits
1786config HAVE_GENERIC_TIF_BITS
1787       bool
1788
1789source "kernel/gcov/Kconfig"
1790
1791source "scripts/gcc-plugins/Kconfig"
1792
1793config FUNCTION_ALIGNMENT_4B
1794	bool
1795
1796config FUNCTION_ALIGNMENT_8B
1797	bool
1798
1799config FUNCTION_ALIGNMENT_16B
1800	bool
1801
1802config FUNCTION_ALIGNMENT_32B
1803	bool
1804
1805config FUNCTION_ALIGNMENT_64B
1806	bool
1807
1808config FUNCTION_ALIGNMENT
1809	int
1810	default 64 if FUNCTION_ALIGNMENT_64B
1811	default 32 if FUNCTION_ALIGNMENT_32B
1812	default 16 if FUNCTION_ALIGNMENT_16B
1813	default 8 if FUNCTION_ALIGNMENT_8B
1814	default 4 if FUNCTION_ALIGNMENT_4B
1815	default 0
1816
1817config CC_HAS_MIN_FUNCTION_ALIGNMENT
1818	# Detect availability of the GCC option -fmin-function-alignment which
1819	# guarantees minimal alignment for all functions, unlike
1820	# -falign-functions which the compiler ignores for cold functions.
1821	def_bool $(cc-option, -fmin-function-alignment=8)
1822
1823config CC_HAS_SANE_FUNCTION_ALIGNMENT
1824	# Set if the guaranteed alignment with -fmin-function-alignment is
1825	# available or extra care is required in the kernel. Clang provides
1826	# strict alignment always, even with -falign-functions.
1827	def_bool CC_HAS_MIN_FUNCTION_ALIGNMENT || CC_IS_CLANG
1828
1829config ARCH_NEED_CMPXCHG_1_EMU
1830	bool
1831
1832config ARCH_WANTS_PRE_LINK_VMLINUX
1833	bool
1834	help
1835	  An architecture can select this if it provides arch/<arch>/tools/Makefile
1836	  with .arch.vmlinux.o target to be linked into vmlinux.
1837
1838config ARCH_HAS_CPU_ATTACK_VECTORS
1839	bool
1840
1841endmenu