| 1 | # SPDX-License-Identifier: GPL-2.0 |
| 2 | # |
| 3 | # General architecture dependent options |
| 4 | # |
| 5 | |
| 6 | # |
| 7 | # Note: arch/$(SRCARCH)/Kconfig needs to be included first so that it can |
| 8 | # override the default values in this file. |
| 9 | # |
| 10 | source "arch/$(SRCARCH)/Kconfig" |
| 11 | |
| 12 | menu "General architecture-dependent options" |
| 13 | |
| 14 | config CRASH_CORE |
| 15 | bool |
| 16 | |
| 17 | config KEXEC_CORE |
| 18 | select CRASH_CORE |
| 19 | bool |
| 20 | |
| 21 | config HAVE_IMA_KEXEC |
| 22 | bool |
| 23 | |
| 24 | config HOTPLUG_SMT |
| 25 | bool |
| 26 | |
| 27 | config OPROFILE |
| 28 | tristate "OProfile system profiling" |
| 29 | depends on PROFILING |
| 30 | depends on HAVE_OPROFILE |
| 31 | select RING_BUFFER |
| 32 | select RING_BUFFER_ALLOW_SWAP |
| 33 | help |
| 34 | OProfile is a profiling system capable of profiling the |
| 35 | whole system, include the kernel, kernel modules, libraries, |
| 36 | and applications. |
| 37 | |
| 38 | If unsure, say N. |
| 39 | |
| 40 | config OPROFILE_EVENT_MULTIPLEX |
| 41 | bool "OProfile multiplexing support (EXPERIMENTAL)" |
| 42 | default n |
| 43 | depends on OPROFILE && X86 |
| 44 | help |
| 45 | The number of hardware counters is limited. The multiplexing |
| 46 | feature enables OProfile to gather more events than counters |
| 47 | are provided by the hardware. This is realized by switching |
| 48 | between events at a user specified time interval. |
| 49 | |
| 50 | If unsure, say N. |
| 51 | |
| 52 | config HAVE_OPROFILE |
| 53 | bool |
| 54 | |
| 55 | config OPROFILE_NMI_TIMER |
| 56 | def_bool y |
| 57 | depends on PERF_EVENTS && HAVE_PERF_EVENTS_NMI && !PPC64 |
| 58 | |
| 59 | config KPROBES |
| 60 | bool "Kprobes" |
| 61 | depends on MODULES |
| 62 | depends on HAVE_KPROBES |
| 63 | select KALLSYMS |
| 64 | help |
| 65 | Kprobes allows you to trap at almost any kernel address and |
| 66 | execute a callback function. register_kprobe() establishes |
| 67 | a probepoint and specifies the callback. Kprobes is useful |
| 68 | for kernel debugging, non-intrusive instrumentation and testing. |
| 69 | If in doubt, say "N". |
| 70 | |
| 71 | config JUMP_LABEL |
| 72 | bool "Optimize very unlikely/likely branches" |
| 73 | depends on HAVE_ARCH_JUMP_LABEL |
| 74 | depends on CC_HAS_ASM_GOTO |
| 75 | help |
| 76 | This option enables a transparent branch optimization that |
| 77 | makes certain almost-always-true or almost-always-false branch |
| 78 | conditions even cheaper to execute within the kernel. |
| 79 | |
| 80 | Certain performance-sensitive kernel code, such as trace points, |
| 81 | scheduler functionality, networking code and KVM have such |
| 82 | branches and include support for this optimization technique. |
| 83 | |
| 84 | If it is detected that the compiler has support for "asm goto", |
| 85 | the kernel will compile such branches with just a nop |
| 86 | instruction. When the condition flag is toggled to true, the |
| 87 | nop will be converted to a jump instruction to execute the |
| 88 | conditional block of instructions. |
| 89 | |
| 90 | This technique lowers overhead and stress on the branch prediction |
| 91 | of the processor and generally makes the kernel faster. The update |
| 92 | of the condition is slower, but those are always very rare. |
| 93 | |
| 94 | ( On 32-bit x86, the necessary options added to the compiler |
| 95 | flags may increase the size of the kernel slightly. ) |
| 96 | |
| 97 | config STATIC_KEYS_SELFTEST |
| 98 | bool "Static key selftest" |
| 99 | depends on JUMP_LABEL |
| 100 | help |
| 101 | Boot time self-test of the branch patching code. |
| 102 | |
| 103 | config OPTPROBES |
| 104 | def_bool y |
| 105 | depends on KPROBES && HAVE_OPTPROBES |
| 106 | select TASKS_RCU if PREEMPT |
| 107 | |
| 108 | config KPROBES_ON_FTRACE |
| 109 | def_bool y |
| 110 | depends on KPROBES && HAVE_KPROBES_ON_FTRACE |
| 111 | depends on DYNAMIC_FTRACE_WITH_REGS |
| 112 | help |
| 113 | If function tracer is enabled and the arch supports full |
| 114 | passing of pt_regs to function tracing, then kprobes can |
| 115 | optimize on top of function tracing. |
| 116 | |
| 117 | config UPROBES |
| 118 | def_bool n |
| 119 | depends on ARCH_SUPPORTS_UPROBES |
| 120 | help |
| 121 | Uprobes is the user-space counterpart to kprobes: they |
| 122 | enable instrumentation applications (such as 'perf probe') |
| 123 | to establish unintrusive probes in user-space binaries and |
| 124 | libraries, by executing handler functions when the probes |
| 125 | are hit by user-space applications. |
| 126 | |
| 127 | ( These probes come in the form of single-byte breakpoints, |
| 128 | managed by the kernel and kept transparent to the probed |
| 129 | application. ) |
| 130 | |
| 131 | config HAVE_EFFICIENT_UNALIGNED_ACCESS |
| 132 | bool |
| 133 | help |
| 134 | Some architectures are unable to perform unaligned accesses |
| 135 | without the use of get_unaligned/put_unaligned. Others are |
| 136 | unable to perform such accesses efficiently (e.g. trap on |
| 137 | unaligned access and require fixing it up in the exception |
| 138 | handler.) |
| 139 | |
| 140 | This symbol should be selected by an architecture if it can |
| 141 | perform unaligned accesses efficiently to allow different |
| 142 | code paths to be selected for these cases. Some network |
| 143 | drivers, for example, could opt to not fix up alignment |
| 144 | problems with received packets if doing so would not help |
| 145 | much. |
| 146 | |
| 147 | See Documentation/unaligned-memory-access.txt for more |
| 148 | information on the topic of unaligned memory accesses. |
| 149 | |
| 150 | config ARCH_USE_BUILTIN_BSWAP |
| 151 | bool |
| 152 | help |
| 153 | Modern versions of GCC (since 4.4) have builtin functions |
| 154 | for handling byte-swapping. Using these, instead of the old |
| 155 | inline assembler that the architecture code provides in the |
| 156 | __arch_bswapXX() macros, allows the compiler to see what's |
| 157 | happening and offers more opportunity for optimisation. In |
| 158 | particular, the compiler will be able to combine the byteswap |
| 159 | with a nearby load or store and use load-and-swap or |
| 160 | store-and-swap instructions if the architecture has them. It |
| 161 | should almost *never* result in code which is worse than the |
| 162 | hand-coded assembler in <asm/swab.h>. But just in case it |
| 163 | does, the use of the builtins is optional. |
| 164 | |
| 165 | Any architecture with load-and-swap or store-and-swap |
| 166 | instructions should set this. And it shouldn't hurt to set it |
| 167 | on architectures that don't have such instructions. |
| 168 | |
| 169 | config KRETPROBES |
| 170 | def_bool y |
| 171 | depends on KPROBES && HAVE_KRETPROBES |
| 172 | |
| 173 | config USER_RETURN_NOTIFIER |
| 174 | bool |
| 175 | depends on HAVE_USER_RETURN_NOTIFIER |
| 176 | help |
| 177 | Provide a kernel-internal notification when a cpu is about to |
| 178 | switch to user mode. |
| 179 | |
| 180 | config HAVE_IOREMAP_PROT |
| 181 | bool |
| 182 | |
| 183 | config HAVE_KPROBES |
| 184 | bool |
| 185 | |
| 186 | config HAVE_KRETPROBES |
| 187 | bool |
| 188 | |
| 189 | config HAVE_OPTPROBES |
| 190 | bool |
| 191 | |
| 192 | config HAVE_KPROBES_ON_FTRACE |
| 193 | bool |
| 194 | |
| 195 | config HAVE_FUNCTION_ERROR_INJECTION |
| 196 | bool |
| 197 | |
| 198 | config HAVE_NMI |
| 199 | bool |
| 200 | |
| 201 | # |
| 202 | # An arch should select this if it provides all these things: |
| 203 | # |
| 204 | # task_pt_regs() in asm/processor.h or asm/ptrace.h |
| 205 | # arch_has_single_step() if there is hardware single-step support |
| 206 | # arch_has_block_step() if there is hardware block-step support |
| 207 | # asm/syscall.h supplying asm-generic/syscall.h interface |
| 208 | # linux/regset.h user_regset interfaces |
| 209 | # CORE_DUMP_USE_REGSET #define'd in linux/elf.h |
| 210 | # TIF_SYSCALL_TRACE calls tracehook_report_syscall_{entry,exit} |
| 211 | # TIF_NOTIFY_RESUME calls tracehook_notify_resume() |
| 212 | # signal delivery calls tracehook_signal_handler() |
| 213 | # |
| 214 | config HAVE_ARCH_TRACEHOOK |
| 215 | bool |
| 216 | |
| 217 | config HAVE_DMA_CONTIGUOUS |
| 218 | bool |
| 219 | |
| 220 | config GENERIC_SMP_IDLE_THREAD |
| 221 | bool |
| 222 | |
| 223 | config GENERIC_IDLE_POLL_SETUP |
| 224 | bool |
| 225 | |
| 226 | config ARCH_HAS_FORTIFY_SOURCE |
| 227 | bool |
| 228 | help |
| 229 | An architecture should select this when it can successfully |
| 230 | build and run with CONFIG_FORTIFY_SOURCE. |
| 231 | |
| 232 | # |
| 233 | # Select if the arch provides a historic keepinit alias for the retain_initrd |
| 234 | # command line option |
| 235 | # |
| 236 | config ARCH_HAS_KEEPINITRD |
| 237 | bool |
| 238 | |
| 239 | # Select if arch has all set_memory_ro/rw/x/nx() functions in asm/cacheflush.h |
| 240 | config ARCH_HAS_SET_MEMORY |
| 241 | bool |
| 242 | |
| 243 | # Select if arch has all set_direct_map_invalid/default() functions |
| 244 | config ARCH_HAS_SET_DIRECT_MAP |
| 245 | bool |
| 246 | |
| 247 | # |
| 248 | # Select if arch has an uncached kernel segment and provides the |
| 249 | # uncached_kernel_address / cached_kernel_address symbols to use it |
| 250 | # |
| 251 | config ARCH_HAS_UNCACHED_SEGMENT |
| 252 | select ARCH_HAS_DMA_PREP_COHERENT |
| 253 | bool |
| 254 | |
| 255 | # Select if arch init_task must go in the __init_task_data section |
| 256 | config ARCH_TASK_STRUCT_ON_STACK |
| 257 | bool |
| 258 | |
| 259 | # Select if arch has its private alloc_task_struct() function |
| 260 | config ARCH_TASK_STRUCT_ALLOCATOR |
| 261 | bool |
| 262 | |
| 263 | config HAVE_ARCH_THREAD_STRUCT_WHITELIST |
| 264 | bool |
| 265 | depends on !ARCH_TASK_STRUCT_ALLOCATOR |
| 266 | help |
| 267 | An architecture should select this to provide hardened usercopy |
| 268 | knowledge about what region of the thread_struct should be |
| 269 | whitelisted for copying to userspace. Normally this is only the |
| 270 | FPU registers. Specifically, arch_thread_struct_whitelist() |
| 271 | should be implemented. Without this, the entire thread_struct |
| 272 | field in task_struct will be left whitelisted. |
| 273 | |
| 274 | # Select if arch has its private alloc_thread_stack() function |
| 275 | config ARCH_THREAD_STACK_ALLOCATOR |
| 276 | bool |
| 277 | |
| 278 | # Select if arch wants to size task_struct dynamically via arch_task_struct_size: |
| 279 | config ARCH_WANTS_DYNAMIC_TASK_STRUCT |
| 280 | bool |
| 281 | |
| 282 | config ARCH_32BIT_OFF_T |
| 283 | bool |
| 284 | depends on !64BIT |
| 285 | help |
| 286 | All new 32-bit architectures should have 64-bit off_t type on |
| 287 | userspace side which corresponds to the loff_t kernel type. This |
| 288 | is the requirement for modern ABIs. Some existing architectures |
| 289 | still support 32-bit off_t. This option is enabled for all such |
| 290 | architectures explicitly. |
| 291 | |
| 292 | config HAVE_REGS_AND_STACK_ACCESS_API |
| 293 | bool |
| 294 | help |
| 295 | This symbol should be selected by an architecure if it supports |
| 296 | the API needed to access registers and stack entries from pt_regs, |
| 297 | declared in asm/ptrace.h |
| 298 | For example the kprobes-based event tracer needs this API. |
| 299 | |
| 300 | config HAVE_RSEQ |
| 301 | bool |
| 302 | depends on HAVE_REGS_AND_STACK_ACCESS_API |
| 303 | help |
| 304 | This symbol should be selected by an architecture if it |
| 305 | supports an implementation of restartable sequences. |
| 306 | |
| 307 | config HAVE_FUNCTION_ARG_ACCESS_API |
| 308 | bool |
| 309 | help |
| 310 | This symbol should be selected by an architecure if it supports |
| 311 | the API needed to access function arguments from pt_regs, |
| 312 | declared in asm/ptrace.h |
| 313 | |
| 314 | config HAVE_CLK |
| 315 | bool |
| 316 | help |
| 317 | The <linux/clk.h> calls support software clock gating and |
| 318 | thus are a key power management tool on many systems. |
| 319 | |
| 320 | config HAVE_HW_BREAKPOINT |
| 321 | bool |
| 322 | depends on PERF_EVENTS |
| 323 | |
| 324 | config HAVE_MIXED_BREAKPOINTS_REGS |
| 325 | bool |
| 326 | depends on HAVE_HW_BREAKPOINT |
| 327 | help |
| 328 | Depending on the arch implementation of hardware breakpoints, |
| 329 | some of them have separate registers for data and instruction |
| 330 | breakpoints addresses, others have mixed registers to store |
| 331 | them but define the access type in a control register. |
| 332 | Select this option if your arch implements breakpoints under the |
| 333 | latter fashion. |
| 334 | |
| 335 | config HAVE_USER_RETURN_NOTIFIER |
| 336 | bool |
| 337 | |
| 338 | config HAVE_PERF_EVENTS_NMI |
| 339 | bool |
| 340 | help |
| 341 | System hardware can generate an NMI using the perf event |
| 342 | subsystem. Also has support for calculating CPU cycle events |
| 343 | to determine how many clock cycles in a given period. |
| 344 | |
| 345 | config HAVE_HARDLOCKUP_DETECTOR_PERF |
| 346 | bool |
| 347 | depends on HAVE_PERF_EVENTS_NMI |
| 348 | help |
| 349 | The arch chooses to use the generic perf-NMI-based hardlockup |
| 350 | detector. Must define HAVE_PERF_EVENTS_NMI. |
| 351 | |
| 352 | config HAVE_NMI_WATCHDOG |
| 353 | depends on HAVE_NMI |
| 354 | bool |
| 355 | help |
| 356 | The arch provides a low level NMI watchdog. It provides |
| 357 | asm/nmi.h, and defines its own arch_touch_nmi_watchdog(). |
| 358 | |
| 359 | config HAVE_HARDLOCKUP_DETECTOR_ARCH |
| 360 | bool |
| 361 | select HAVE_NMI_WATCHDOG |
| 362 | help |
| 363 | The arch chooses to provide its own hardlockup detector, which is |
| 364 | a superset of the HAVE_NMI_WATCHDOG. It also conforms to config |
| 365 | interfaces and parameters provided by hardlockup detector subsystem. |
| 366 | |
| 367 | config HAVE_PERF_REGS |
| 368 | bool |
| 369 | help |
| 370 | Support selective register dumps for perf events. This includes |
| 371 | bit-mapping of each registers and a unique architecture id. |
| 372 | |
| 373 | config HAVE_PERF_USER_STACK_DUMP |
| 374 | bool |
| 375 | help |
| 376 | Support user stack dumps for perf event samples. This needs |
| 377 | access to the user stack pointer which is not unified across |
| 378 | architectures. |
| 379 | |
| 380 | config HAVE_ARCH_JUMP_LABEL |
| 381 | bool |
| 382 | |
| 383 | config HAVE_ARCH_JUMP_LABEL_RELATIVE |
| 384 | bool |
| 385 | |
| 386 | config HAVE_RCU_TABLE_FREE |
| 387 | bool |
| 388 | |
| 389 | config HAVE_RCU_TABLE_NO_INVALIDATE |
| 390 | bool |
| 391 | |
| 392 | config HAVE_MMU_GATHER_PAGE_SIZE |
| 393 | bool |
| 394 | |
| 395 | config HAVE_MMU_GATHER_NO_GATHER |
| 396 | bool |
| 397 | |
| 398 | config ARCH_HAVE_NMI_SAFE_CMPXCHG |
| 399 | bool |
| 400 | |
| 401 | config HAVE_ALIGNED_STRUCT_PAGE |
| 402 | bool |
| 403 | help |
| 404 | This makes sure that struct pages are double word aligned and that |
| 405 | e.g. the SLUB allocator can perform double word atomic operations |
| 406 | on a struct page for better performance. However selecting this |
| 407 | might increase the size of a struct page by a word. |
| 408 | |
| 409 | config HAVE_CMPXCHG_LOCAL |
| 410 | bool |
| 411 | |
| 412 | config HAVE_CMPXCHG_DOUBLE |
| 413 | bool |
| 414 | |
| 415 | config ARCH_WEAK_RELEASE_ACQUIRE |
| 416 | bool |
| 417 | |
| 418 | config ARCH_WANT_IPC_PARSE_VERSION |
| 419 | bool |
| 420 | |
| 421 | config ARCH_WANT_COMPAT_IPC_PARSE_VERSION |
| 422 | bool |
| 423 | |
| 424 | config ARCH_WANT_OLD_COMPAT_IPC |
| 425 | select ARCH_WANT_COMPAT_IPC_PARSE_VERSION |
| 426 | bool |
| 427 | |
| 428 | config HAVE_ARCH_SECCOMP_FILTER |
| 429 | bool |
| 430 | help |
| 431 | An arch should select this symbol if it provides all of these things: |
| 432 | - syscall_get_arch() |
| 433 | - syscall_get_arguments() |
| 434 | - syscall_rollback() |
| 435 | - syscall_set_return_value() |
| 436 | - SIGSYS siginfo_t support |
| 437 | - secure_computing is called from a ptrace_event()-safe context |
| 438 | - secure_computing return value is checked and a return value of -1 |
| 439 | results in the system call being skipped immediately. |
| 440 | - seccomp syscall wired up |
| 441 | |
| 442 | config SECCOMP_FILTER |
| 443 | def_bool y |
| 444 | depends on HAVE_ARCH_SECCOMP_FILTER && SECCOMP && NET |
| 445 | help |
| 446 | Enable tasks to build secure computing environments defined |
| 447 | in terms of Berkeley Packet Filter programs which implement |
| 448 | task-defined system call filtering polices. |
| 449 | |
| 450 | See Documentation/userspace-api/seccomp_filter.rst for details. |
| 451 | |
| 452 | config HAVE_ARCH_STACKLEAK |
| 453 | bool |
| 454 | help |
| 455 | An architecture should select this if it has the code which |
| 456 | fills the used part of the kernel stack with the STACKLEAK_POISON |
| 457 | value before returning from system calls. |
| 458 | |
| 459 | config HAVE_STACKPROTECTOR |
| 460 | bool |
| 461 | help |
| 462 | An arch should select this symbol if: |
| 463 | - it has implemented a stack canary (e.g. __stack_chk_guard) |
| 464 | |
| 465 | config CC_HAS_STACKPROTECTOR_NONE |
| 466 | def_bool $(cc-option,-fno-stack-protector) |
| 467 | |
| 468 | config STACKPROTECTOR |
| 469 | bool "Stack Protector buffer overflow detection" |
| 470 | depends on HAVE_STACKPROTECTOR |
| 471 | depends on $(cc-option,-fstack-protector) |
| 472 | default y |
| 473 | help |
| 474 | This option turns on the "stack-protector" GCC feature. This |
| 475 | feature puts, at the beginning of functions, a canary value on |
| 476 | the stack just before the return address, and validates |
| 477 | the value just before actually returning. Stack based buffer |
| 478 | overflows (that need to overwrite this return address) now also |
| 479 | overwrite the canary, which gets detected and the attack is then |
| 480 | neutralized via a kernel panic. |
| 481 | |
| 482 | Functions will have the stack-protector canary logic added if they |
| 483 | have an 8-byte or larger character array on the stack. |
| 484 | |
| 485 | This feature requires gcc version 4.2 or above, or a distribution |
| 486 | gcc with the feature backported ("-fstack-protector"). |
| 487 | |
| 488 | On an x86 "defconfig" build, this feature adds canary checks to |
| 489 | about 3% of all kernel functions, which increases kernel code size |
| 490 | by about 0.3%. |
| 491 | |
| 492 | config STACKPROTECTOR_STRONG |
| 493 | bool "Strong Stack Protector" |
| 494 | depends on STACKPROTECTOR |
| 495 | depends on $(cc-option,-fstack-protector-strong) |
| 496 | default y |
| 497 | help |
| 498 | Functions will have the stack-protector canary logic added in any |
| 499 | of the following conditions: |
| 500 | |
| 501 | - local variable's address used as part of the right hand side of an |
| 502 | assignment or function argument |
| 503 | - local variable is an array (or union containing an array), |
| 504 | regardless of array type or length |
| 505 | - uses register local variables |
| 506 | |
| 507 | This feature requires gcc version 4.9 or above, or a distribution |
| 508 | gcc with the feature backported ("-fstack-protector-strong"). |
| 509 | |
| 510 | On an x86 "defconfig" build, this feature adds canary checks to |
| 511 | about 20% of all kernel functions, which increases the kernel code |
| 512 | size by about 2%. |
| 513 | |
| 514 | config HAVE_ARCH_WITHIN_STACK_FRAMES |
| 515 | bool |
| 516 | help |
| 517 | An architecture should select this if it can walk the kernel stack |
| 518 | frames to determine if an object is part of either the arguments |
| 519 | or local variables (i.e. that it excludes saved return addresses, |
| 520 | and similar) by implementing an inline arch_within_stack_frames(), |
| 521 | which is used by CONFIG_HARDENED_USERCOPY. |
| 522 | |
| 523 | config HAVE_CONTEXT_TRACKING |
| 524 | bool |
| 525 | help |
| 526 | Provide kernel/user boundaries probes necessary for subsystems |
| 527 | that need it, such as userspace RCU extended quiescent state. |
| 528 | Syscalls need to be wrapped inside user_exit()-user_enter() through |
| 529 | the slow path using TIF_NOHZ flag. Exceptions handlers must be |
| 530 | wrapped as well. Irqs are already protected inside |
| 531 | rcu_irq_enter/rcu_irq_exit() but preemption or signal handling on |
| 532 | irq exit still need to be protected. |
| 533 | |
| 534 | config HAVE_VIRT_CPU_ACCOUNTING |
| 535 | bool |
| 536 | |
| 537 | config ARCH_HAS_SCALED_CPUTIME |
| 538 | bool |
| 539 | |
| 540 | config HAVE_VIRT_CPU_ACCOUNTING_GEN |
| 541 | bool |
| 542 | default y if 64BIT |
| 543 | help |
| 544 | With VIRT_CPU_ACCOUNTING_GEN, cputime_t becomes 64-bit. |
| 545 | Before enabling this option, arch code must be audited |
| 546 | to ensure there are no races in concurrent read/write of |
| 547 | cputime_t. For example, reading/writing 64-bit cputime_t on |
| 548 | some 32-bit arches may require multiple accesses, so proper |
| 549 | locking is needed to protect against concurrent accesses. |
| 550 | |
| 551 | |
| 552 | config HAVE_IRQ_TIME_ACCOUNTING |
| 553 | bool |
| 554 | help |
| 555 | Archs need to ensure they use a high enough resolution clock to |
| 556 | support irq time accounting and then call enable_sched_clock_irqtime(). |
| 557 | |
| 558 | config HAVE_MOVE_PMD |
| 559 | bool |
| 560 | help |
| 561 | Archs that select this are able to move page tables at the PMD level. |
| 562 | |
| 563 | config HAVE_ARCH_TRANSPARENT_HUGEPAGE |
| 564 | bool |
| 565 | |
| 566 | config HAVE_ARCH_TRANSPARENT_HUGEPAGE_PUD |
| 567 | bool |
| 568 | |
| 569 | config HAVE_ARCH_HUGE_VMAP |
| 570 | bool |
| 571 | |
| 572 | config ARCH_WANT_HUGE_PMD_SHARE |
| 573 | bool |
| 574 | |
| 575 | config HAVE_ARCH_SOFT_DIRTY |
| 576 | bool |
| 577 | |
| 578 | config HAVE_MOD_ARCH_SPECIFIC |
| 579 | bool |
| 580 | help |
| 581 | The arch uses struct mod_arch_specific to store data. Many arches |
| 582 | just need a simple module loader without arch specific data - those |
| 583 | should not enable this. |
| 584 | |
| 585 | config MODULES_USE_ELF_RELA |
| 586 | bool |
| 587 | help |
| 588 | Modules only use ELF RELA relocations. Modules with ELF REL |
| 589 | relocations will give an error. |
| 590 | |
| 591 | config MODULES_USE_ELF_REL |
| 592 | bool |
| 593 | help |
| 594 | Modules only use ELF REL relocations. Modules with ELF RELA |
| 595 | relocations will give an error. |
| 596 | |
| 597 | config HAVE_IRQ_EXIT_ON_IRQ_STACK |
| 598 | bool |
| 599 | help |
| 600 | Architecture doesn't only execute the irq handler on the irq stack |
| 601 | but also irq_exit(). This way we can process softirqs on this irq |
| 602 | stack instead of switching to a new one when we call __do_softirq() |
| 603 | in the end of an hardirq. |
| 604 | This spares a stack switch and improves cache usage on softirq |
| 605 | processing. |
| 606 | |
| 607 | config PGTABLE_LEVELS |
| 608 | int |
| 609 | default 2 |
| 610 | |
| 611 | config ARCH_HAS_ELF_RANDOMIZE |
| 612 | bool |
| 613 | help |
| 614 | An architecture supports choosing randomized locations for |
| 615 | stack, mmap, brk, and ET_DYN. Defined functions: |
| 616 | - arch_mmap_rnd() |
| 617 | - arch_randomize_brk() |
| 618 | |
| 619 | config HAVE_ARCH_MMAP_RND_BITS |
| 620 | bool |
| 621 | help |
| 622 | An arch should select this symbol if it supports setting a variable |
| 623 | number of bits for use in establishing the base address for mmap |
| 624 | allocations, has MMU enabled and provides values for both: |
| 625 | - ARCH_MMAP_RND_BITS_MIN |
| 626 | - ARCH_MMAP_RND_BITS_MAX |
| 627 | |
| 628 | config HAVE_EXIT_THREAD |
| 629 | bool |
| 630 | help |
| 631 | An architecture implements exit_thread. |
| 632 | |
| 633 | config ARCH_MMAP_RND_BITS_MIN |
| 634 | int |
| 635 | |
| 636 | config ARCH_MMAP_RND_BITS_MAX |
| 637 | int |
| 638 | |
| 639 | config ARCH_MMAP_RND_BITS_DEFAULT |
| 640 | int |
| 641 | |
| 642 | config ARCH_MMAP_RND_BITS |
| 643 | int "Number of bits to use for ASLR of mmap base address" if EXPERT |
| 644 | range ARCH_MMAP_RND_BITS_MIN ARCH_MMAP_RND_BITS_MAX |
| 645 | default ARCH_MMAP_RND_BITS_DEFAULT if ARCH_MMAP_RND_BITS_DEFAULT |
| 646 | default ARCH_MMAP_RND_BITS_MIN |
| 647 | depends on HAVE_ARCH_MMAP_RND_BITS |
| 648 | help |
| 649 | This value can be used to select the number of bits to use to |
| 650 | determine the random offset to the base address of vma regions |
| 651 | resulting from mmap allocations. This value will be bounded |
| 652 | by the architecture's minimum and maximum supported values. |
| 653 | |
| 654 | This value can be changed after boot using the |
| 655 | /proc/sys/vm/mmap_rnd_bits tunable |
| 656 | |
| 657 | config HAVE_ARCH_MMAP_RND_COMPAT_BITS |
| 658 | bool |
| 659 | help |
| 660 | An arch should select this symbol if it supports running applications |
| 661 | in compatibility mode, supports setting a variable number of bits for |
| 662 | use in establishing the base address for mmap allocations, has MMU |
| 663 | enabled and provides values for both: |
| 664 | - ARCH_MMAP_RND_COMPAT_BITS_MIN |
| 665 | - ARCH_MMAP_RND_COMPAT_BITS_MAX |
| 666 | |
| 667 | config ARCH_MMAP_RND_COMPAT_BITS_MIN |
| 668 | int |
| 669 | |
| 670 | config ARCH_MMAP_RND_COMPAT_BITS_MAX |
| 671 | int |
| 672 | |
| 673 | config ARCH_MMAP_RND_COMPAT_BITS_DEFAULT |
| 674 | int |
| 675 | |
| 676 | config ARCH_MMAP_RND_COMPAT_BITS |
| 677 | int "Number of bits to use for ASLR of mmap base address for compatible applications" if EXPERT |
| 678 | range ARCH_MMAP_RND_COMPAT_BITS_MIN ARCH_MMAP_RND_COMPAT_BITS_MAX |
| 679 | default ARCH_MMAP_RND_COMPAT_BITS_DEFAULT if ARCH_MMAP_RND_COMPAT_BITS_DEFAULT |
| 680 | default ARCH_MMAP_RND_COMPAT_BITS_MIN |
| 681 | depends on HAVE_ARCH_MMAP_RND_COMPAT_BITS |
| 682 | help |
| 683 | This value can be used to select the number of bits to use to |
| 684 | determine the random offset to the base address of vma regions |
| 685 | resulting from mmap allocations for compatible applications This |
| 686 | value will be bounded by the architecture's minimum and maximum |
| 687 | supported values. |
| 688 | |
| 689 | This value can be changed after boot using the |
| 690 | /proc/sys/vm/mmap_rnd_compat_bits tunable |
| 691 | |
| 692 | config HAVE_ARCH_COMPAT_MMAP_BASES |
| 693 | bool |
| 694 | help |
| 695 | This allows 64bit applications to invoke 32-bit mmap() syscall |
| 696 | and vice-versa 32-bit applications to call 64-bit mmap(). |
| 697 | Required for applications doing different bitness syscalls. |
| 698 | |
| 699 | config HAVE_COPY_THREAD_TLS |
| 700 | bool |
| 701 | help |
| 702 | Architecture provides copy_thread_tls to accept tls argument via |
| 703 | normal C parameter passing, rather than extracting the syscall |
| 704 | argument from pt_regs. |
| 705 | |
| 706 | config HAVE_STACK_VALIDATION |
| 707 | bool |
| 708 | help |
| 709 | Architecture supports the 'objtool check' host tool command, which |
| 710 | performs compile-time stack metadata validation. |
| 711 | |
| 712 | config HAVE_RELIABLE_STACKTRACE |
| 713 | bool |
| 714 | help |
| 715 | Architecture has a save_stack_trace_tsk_reliable() function which |
| 716 | only returns a stack trace if it can guarantee the trace is reliable. |
| 717 | |
| 718 | config HAVE_ARCH_HASH |
| 719 | bool |
| 720 | default n |
| 721 | help |
| 722 | If this is set, the architecture provides an <asm/hash.h> |
| 723 | file which provides platform-specific implementations of some |
| 724 | functions in <linux/hash.h> or fs/namei.c. |
| 725 | |
| 726 | config HAVE_ARCH_NVRAM_OPS |
| 727 | bool |
| 728 | |
| 729 | config ISA_BUS_API |
| 730 | def_bool ISA |
| 731 | |
| 732 | # |
| 733 | # ABI hall of shame |
| 734 | # |
| 735 | config CLONE_BACKWARDS |
| 736 | bool |
| 737 | help |
| 738 | Architecture has tls passed as the 4th argument of clone(2), |
| 739 | not the 5th one. |
| 740 | |
| 741 | config CLONE_BACKWARDS2 |
| 742 | bool |
| 743 | help |
| 744 | Architecture has the first two arguments of clone(2) swapped. |
| 745 | |
| 746 | config CLONE_BACKWARDS3 |
| 747 | bool |
| 748 | help |
| 749 | Architecture has tls passed as the 3rd argument of clone(2), |
| 750 | not the 5th one. |
| 751 | |
| 752 | config ODD_RT_SIGACTION |
| 753 | bool |
| 754 | help |
| 755 | Architecture has unusual rt_sigaction(2) arguments |
| 756 | |
| 757 | config OLD_SIGSUSPEND |
| 758 | bool |
| 759 | help |
| 760 | Architecture has old sigsuspend(2) syscall, of one-argument variety |
| 761 | |
| 762 | config OLD_SIGSUSPEND3 |
| 763 | bool |
| 764 | help |
| 765 | Even weirder antique ABI - three-argument sigsuspend(2) |
| 766 | |
| 767 | config OLD_SIGACTION |
| 768 | bool |
| 769 | help |
| 770 | Architecture has old sigaction(2) syscall. Nope, not the same |
| 771 | as OLD_SIGSUSPEND | OLD_SIGSUSPEND3 - alpha has sigsuspend(2), |
| 772 | but fairly different variant of sigaction(2), thanks to OSF/1 |
| 773 | compatibility... |
| 774 | |
| 775 | config COMPAT_OLD_SIGACTION |
| 776 | bool |
| 777 | |
| 778 | config 64BIT_TIME |
| 779 | def_bool y |
| 780 | help |
| 781 | This should be selected by all architectures that need to support |
| 782 | new system calls with a 64-bit time_t. This is relevant on all 32-bit |
| 783 | architectures, and 64-bit architectures as part of compat syscall |
| 784 | handling. |
| 785 | |
| 786 | config COMPAT_32BIT_TIME |
| 787 | def_bool !64BIT || COMPAT |
| 788 | help |
| 789 | This enables 32 bit time_t support in addition to 64 bit time_t support. |
| 790 | This is relevant on all 32-bit architectures, and 64-bit architectures |
| 791 | as part of compat syscall handling. |
| 792 | |
| 793 | config ARCH_NO_COHERENT_DMA_MMAP |
| 794 | bool |
| 795 | |
| 796 | config ARCH_NO_PREEMPT |
| 797 | bool |
| 798 | |
| 799 | config ARCH_SUPPORTS_RT |
| 800 | bool |
| 801 | |
| 802 | config CPU_NO_EFFICIENT_FFS |
| 803 | def_bool n |
| 804 | |
| 805 | config HAVE_ARCH_VMAP_STACK |
| 806 | def_bool n |
| 807 | help |
| 808 | An arch should select this symbol if it can support kernel stacks |
| 809 | in vmalloc space. This means: |
| 810 | |
| 811 | - vmalloc space must be large enough to hold many kernel stacks. |
| 812 | This may rule out many 32-bit architectures. |
| 813 | |
| 814 | - Stacks in vmalloc space need to work reliably. For example, if |
| 815 | vmap page tables are created on demand, either this mechanism |
| 816 | needs to work while the stack points to a virtual address with |
| 817 | unpopulated page tables or arch code (switch_to() and switch_mm(), |
| 818 | most likely) needs to ensure that the stack's page table entries |
| 819 | are populated before running on a possibly unpopulated stack. |
| 820 | |
| 821 | - If the stack overflows into a guard page, something reasonable |
| 822 | should happen. The definition of "reasonable" is flexible, but |
| 823 | instantly rebooting without logging anything would be unfriendly. |
| 824 | |
| 825 | config VMAP_STACK |
| 826 | default y |
| 827 | bool "Use a virtually-mapped stack" |
| 828 | depends on HAVE_ARCH_VMAP_STACK && !KASAN |
| 829 | ---help--- |
| 830 | Enable this if you want the use virtually-mapped kernel stacks |
| 831 | with guard pages. This causes kernel stack overflows to be |
| 832 | caught immediately rather than causing difficult-to-diagnose |
| 833 | corruption. |
| 834 | |
| 835 | This is presently incompatible with KASAN because KASAN expects |
| 836 | the stack to map directly to the KASAN shadow map using a formula |
| 837 | that is incorrect if the stack is in vmalloc space. |
| 838 | |
| 839 | config ARCH_OPTIONAL_KERNEL_RWX |
| 840 | def_bool n |
| 841 | |
| 842 | config ARCH_OPTIONAL_KERNEL_RWX_DEFAULT |
| 843 | def_bool n |
| 844 | |
| 845 | config ARCH_HAS_STRICT_KERNEL_RWX |
| 846 | def_bool n |
| 847 | |
| 848 | config STRICT_KERNEL_RWX |
| 849 | bool "Make kernel text and rodata read-only" if ARCH_OPTIONAL_KERNEL_RWX |
| 850 | depends on ARCH_HAS_STRICT_KERNEL_RWX |
| 851 | default !ARCH_OPTIONAL_KERNEL_RWX || ARCH_OPTIONAL_KERNEL_RWX_DEFAULT |
| 852 | help |
| 853 | If this is set, kernel text and rodata memory will be made read-only, |
| 854 | and non-text memory will be made non-executable. This provides |
| 855 | protection against certain security exploits (e.g. executing the heap |
| 856 | or modifying text) |
| 857 | |
| 858 | These features are considered standard security practice these days. |
| 859 | You should say Y here in almost all cases. |
| 860 | |
| 861 | config ARCH_HAS_STRICT_MODULE_RWX |
| 862 | def_bool n |
| 863 | |
| 864 | config STRICT_MODULE_RWX |
| 865 | bool "Set loadable kernel module data as NX and text as RO" if ARCH_OPTIONAL_KERNEL_RWX |
| 866 | depends on ARCH_HAS_STRICT_MODULE_RWX && MODULES |
| 867 | default !ARCH_OPTIONAL_KERNEL_RWX || ARCH_OPTIONAL_KERNEL_RWX_DEFAULT |
| 868 | help |
| 869 | If this is set, module text and rodata memory will be made read-only, |
| 870 | and non-text memory will be made non-executable. This provides |
| 871 | protection against certain security exploits (e.g. writing to text) |
| 872 | |
| 873 | # select if the architecture provides an asm/dma-direct.h header |
| 874 | config ARCH_HAS_PHYS_TO_DMA |
| 875 | bool |
| 876 | |
| 877 | config ARCH_HAS_REFCOUNT |
| 878 | bool |
| 879 | help |
| 880 | An architecture selects this when it has implemented refcount_t |
| 881 | using open coded assembly primitives that provide an optimized |
| 882 | refcount_t implementation, possibly at the expense of some full |
| 883 | refcount state checks of CONFIG_REFCOUNT_FULL=y. |
| 884 | |
| 885 | The refcount overflow check behavior, however, must be retained. |
| 886 | Catching overflows is the primary security concern for protecting |
| 887 | against bugs in reference counts. |
| 888 | |
| 889 | config REFCOUNT_FULL |
| 890 | bool "Perform full reference count validation at the expense of speed" |
| 891 | help |
| 892 | Enabling this switches the refcounting infrastructure from a fast |
| 893 | unchecked atomic_t implementation to a fully state checked |
| 894 | implementation, which can be (slightly) slower but provides protections |
| 895 | against various use-after-free conditions that can be used in |
| 896 | security flaw exploits. |
| 897 | |
| 898 | config HAVE_ARCH_COMPILER_H |
| 899 | bool |
| 900 | help |
| 901 | An architecture can select this if it provides an |
| 902 | asm/compiler.h header that should be included after |
| 903 | linux/compiler-*.h in order to override macro definitions that those |
| 904 | headers generally provide. |
| 905 | |
| 906 | config HAVE_ARCH_PREL32_RELOCATIONS |
| 907 | bool |
| 908 | help |
| 909 | May be selected by an architecture if it supports place-relative |
| 910 | 32-bit relocations, both in the toolchain and in the module loader, |
| 911 | in which case relative references can be used in special sections |
| 912 | for PCI fixup, initcalls etc which are only half the size on 64 bit |
| 913 | architectures, and don't require runtime relocation on relocatable |
| 914 | kernels. |
| 915 | |
| 916 | config ARCH_USE_MEMREMAP_PROT |
| 917 | bool |
| 918 | |
| 919 | config LOCK_EVENT_COUNTS |
| 920 | bool "Locking event counts collection" |
| 921 | depends on DEBUG_FS |
| 922 | ---help--- |
| 923 | Enable light-weight counting of various locking related events |
| 924 | in the system with minimal performance impact. This reduces |
| 925 | the chance of application behavior change because of timing |
| 926 | differences. The counts are reported via debugfs. |
| 927 | |
| 928 | source "kernel/gcov/Kconfig" |
| 929 | |
| 930 | source "scripts/gcc-plugins/Kconfig" |
| 931 | |
| 932 | endmenu |