1# 2# General architecture dependent options 3# 4 5config CRASH_CORE 6 bool 7 8config KEXEC_CORE 9 select CRASH_CORE 10 bool 11 12config HAVE_IMA_KEXEC 13 bool 14 15config OPROFILE 16 tristate "OProfile system profiling" 17 depends on PROFILING 18 depends on HAVE_OPROFILE 19 select RING_BUFFER 20 select RING_BUFFER_ALLOW_SWAP 21 help 22 OProfile is a profiling system capable of profiling the 23 whole system, include the kernel, kernel modules, libraries, 24 and applications. 25 26 If unsure, say N. 27 28config OPROFILE_EVENT_MULTIPLEX 29 bool "OProfile multiplexing support (EXPERIMENTAL)" 30 default n 31 depends on OPROFILE && X86 32 help 33 The number of hardware counters is limited. The multiplexing 34 feature enables OProfile to gather more events than counters 35 are provided by the hardware. This is realized by switching 36 between events at a user specified time interval. 37 38 If unsure, say N. 39 40config HAVE_OPROFILE 41 bool 42 43config OPROFILE_NMI_TIMER 44 def_bool y 45 depends on PERF_EVENTS && HAVE_PERF_EVENTS_NMI && !PPC64 46 47config KPROBES 48 bool "Kprobes" 49 depends on MODULES 50 depends on HAVE_KPROBES 51 select KALLSYMS 52 help 53 Kprobes allows you to trap at almost any kernel address and 54 execute a callback function. register_kprobe() establishes 55 a probepoint and specifies the callback. Kprobes is useful 56 for kernel debugging, non-intrusive instrumentation and testing. 57 If in doubt, say "N". 58 59config JUMP_LABEL 60 bool "Optimize very unlikely/likely branches" 61 depends on HAVE_ARCH_JUMP_LABEL 62 help 63 This option enables a transparent branch optimization that 64 makes certain almost-always-true or almost-always-false branch 65 conditions even cheaper to execute within the kernel. 66 67 Certain performance-sensitive kernel code, such as trace points, 68 scheduler functionality, networking code and KVM have such 69 branches and include support for this optimization technique. 70 71 If it is detected that the compiler has support for "asm goto", 72 the kernel will compile such branches with just a nop 73 instruction. When the condition flag is toggled to true, the 74 nop will be converted to a jump instruction to execute the 75 conditional block of instructions. 76 77 This technique lowers overhead and stress on the branch prediction 78 of the processor and generally makes the kernel faster. The update 79 of the condition is slower, but those are always very rare. 80 81 ( On 32-bit x86, the necessary options added to the compiler 82 flags may increase the size of the kernel slightly. ) 83 84config STATIC_KEYS_SELFTEST 85 bool "Static key selftest" 86 depends on JUMP_LABEL 87 help 88 Boot time self-test of the branch patching code. 89 90config OPTPROBES 91 def_bool y 92 depends on KPROBES && HAVE_OPTPROBES 93 depends on !PREEMPT 94 95config KPROBES_ON_FTRACE 96 def_bool y 97 depends on KPROBES && HAVE_KPROBES_ON_FTRACE 98 depends on DYNAMIC_FTRACE_WITH_REGS 99 help 100 If function tracer is enabled and the arch supports full 101 passing of pt_regs to function tracing, then kprobes can 102 optimize on top of function tracing. 103 104config UPROBES 105 def_bool n 106 depends on ARCH_SUPPORTS_UPROBES 107 help 108 Uprobes is the user-space counterpart to kprobes: they 109 enable instrumentation applications (such as 'perf probe') 110 to establish unintrusive probes in user-space binaries and 111 libraries, by executing handler functions when the probes 112 are hit by user-space applications. 113 114 ( These probes come in the form of single-byte breakpoints, 115 managed by the kernel and kept transparent to the probed 116 application. ) 117 118config HAVE_64BIT_ALIGNED_ACCESS 119 def_bool 64BIT && !HAVE_EFFICIENT_UNALIGNED_ACCESS 120 help 121 Some architectures require 64 bit accesses to be 64 bit 122 aligned, which also requires structs containing 64 bit values 123 to be 64 bit aligned too. This includes some 32 bit 124 architectures which can do 64 bit accesses, as well as 64 bit 125 architectures without unaligned access. 126 127 This symbol should be selected by an architecture if 64 bit 128 accesses are required to be 64 bit aligned in this way even 129 though it is not a 64 bit architecture. 130 131 See Documentation/unaligned-memory-access.txt for more 132 information on the topic of unaligned memory accesses. 133 134config HAVE_EFFICIENT_UNALIGNED_ACCESS 135 bool 136 help 137 Some architectures are unable to perform unaligned accesses 138 without the use of get_unaligned/put_unaligned. Others are 139 unable to perform such accesses efficiently (e.g. trap on 140 unaligned access and require fixing it up in the exception 141 handler.) 142 143 This symbol should be selected by an architecture if it can 144 perform unaligned accesses efficiently to allow different 145 code paths to be selected for these cases. Some network 146 drivers, for example, could opt to not fix up alignment 147 problems with received packets if doing so would not help 148 much. 149 150 See Documentation/unaligned-memory-access.txt for more 151 information on the topic of unaligned memory accesses. 152 153config ARCH_USE_BUILTIN_BSWAP 154 bool 155 help 156 Modern versions of GCC (since 4.4) have builtin functions 157 for handling byte-swapping. Using these, instead of the old 158 inline assembler that the architecture code provides in the 159 __arch_bswapXX() macros, allows the compiler to see what's 160 happening and offers more opportunity for optimisation. In 161 particular, the compiler will be able to combine the byteswap 162 with a nearby load or store and use load-and-swap or 163 store-and-swap instructions if the architecture has them. It 164 should almost *never* result in code which is worse than the 165 hand-coded assembler in <asm/swab.h>. But just in case it 166 does, the use of the builtins is optional. 167 168 Any architecture with load-and-swap or store-and-swap 169 instructions should set this. And it shouldn't hurt to set it 170 on architectures that don't have such instructions. 171 172config KRETPROBES 173 def_bool y 174 depends on KPROBES && HAVE_KRETPROBES 175 176config USER_RETURN_NOTIFIER 177 bool 178 depends on HAVE_USER_RETURN_NOTIFIER 179 help 180 Provide a kernel-internal notification when a cpu is about to 181 switch to user mode. 182 183config HAVE_IOREMAP_PROT 184 bool 185 186config HAVE_KPROBES 187 bool 188 189config HAVE_KRETPROBES 190 bool 191 192config HAVE_OPTPROBES 193 bool 194 195config HAVE_KPROBES_ON_FTRACE 196 bool 197 198config HAVE_NMI 199 bool 200 201config HAVE_NMI_WATCHDOG 202 depends on HAVE_NMI 203 bool 204# 205# An arch should select this if it provides all these things: 206# 207# task_pt_regs() in asm/processor.h or asm/ptrace.h 208# arch_has_single_step() if there is hardware single-step support 209# arch_has_block_step() if there is hardware block-step support 210# asm/syscall.h supplying asm-generic/syscall.h interface 211# linux/regset.h user_regset interfaces 212# CORE_DUMP_USE_REGSET #define'd in linux/elf.h 213# TIF_SYSCALL_TRACE calls tracehook_report_syscall_{entry,exit} 214# TIF_NOTIFY_RESUME calls tracehook_notify_resume() 215# signal delivery calls tracehook_signal_handler() 216# 217config HAVE_ARCH_TRACEHOOK 218 bool 219 220config HAVE_DMA_CONTIGUOUS 221 bool 222 223config GENERIC_SMP_IDLE_THREAD 224 bool 225 226config GENERIC_IDLE_POLL_SETUP 227 bool 228 229# Select if arch has all set_memory_ro/rw/x/nx() functions in asm/cacheflush.h 230config ARCH_HAS_SET_MEMORY 231 bool 232 233# Select if arch init_task initializer is different to init/init_task.c 234config ARCH_INIT_TASK 235 bool 236 237# Select if arch has its private alloc_task_struct() function 238config ARCH_TASK_STRUCT_ALLOCATOR 239 bool 240 241# Select if arch has its private alloc_thread_stack() function 242config ARCH_THREAD_STACK_ALLOCATOR 243 bool 244 245# Select if arch wants to size task_struct dynamically via arch_task_struct_size: 246config ARCH_WANTS_DYNAMIC_TASK_STRUCT 247 bool 248 249config HAVE_REGS_AND_STACK_ACCESS_API 250 bool 251 help 252 This symbol should be selected by an architecure if it supports 253 the API needed to access registers and stack entries from pt_regs, 254 declared in asm/ptrace.h 255 For example the kprobes-based event tracer needs this API. 256 257config HAVE_CLK 258 bool 259 help 260 The <linux/clk.h> calls support software clock gating and 261 thus are a key power management tool on many systems. 262 263config HAVE_DMA_API_DEBUG 264 bool 265 266config HAVE_HW_BREAKPOINT 267 bool 268 depends on PERF_EVENTS 269 270config HAVE_MIXED_BREAKPOINTS_REGS 271 bool 272 depends on HAVE_HW_BREAKPOINT 273 help 274 Depending on the arch implementation of hardware breakpoints, 275 some of them have separate registers for data and instruction 276 breakpoints addresses, others have mixed registers to store 277 them but define the access type in a control register. 278 Select this option if your arch implements breakpoints under the 279 latter fashion. 280 281config HAVE_USER_RETURN_NOTIFIER 282 bool 283 284config HAVE_PERF_EVENTS_NMI 285 bool 286 help 287 System hardware can generate an NMI using the perf event 288 subsystem. Also has support for calculating CPU cycle events 289 to determine how many clock cycles in a given period. 290 291config HAVE_PERF_REGS 292 bool 293 help 294 Support selective register dumps for perf events. This includes 295 bit-mapping of each registers and a unique architecture id. 296 297config HAVE_PERF_USER_STACK_DUMP 298 bool 299 help 300 Support user stack dumps for perf event samples. This needs 301 access to the user stack pointer which is not unified across 302 architectures. 303 304config HAVE_ARCH_JUMP_LABEL 305 bool 306 307config HAVE_RCU_TABLE_FREE 308 bool 309 310config ARCH_HAVE_NMI_SAFE_CMPXCHG 311 bool 312 313config HAVE_ALIGNED_STRUCT_PAGE 314 bool 315 help 316 This makes sure that struct pages are double word aligned and that 317 e.g. the SLUB allocator can perform double word atomic operations 318 on a struct page for better performance. However selecting this 319 might increase the size of a struct page by a word. 320 321config HAVE_CMPXCHG_LOCAL 322 bool 323 324config HAVE_CMPXCHG_DOUBLE 325 bool 326 327config ARCH_WANT_IPC_PARSE_VERSION 328 bool 329 330config ARCH_WANT_COMPAT_IPC_PARSE_VERSION 331 bool 332 333config ARCH_WANT_OLD_COMPAT_IPC 334 select ARCH_WANT_COMPAT_IPC_PARSE_VERSION 335 bool 336 337config HAVE_ARCH_SECCOMP_FILTER 338 bool 339 help 340 An arch should select this symbol if it provides all of these things: 341 - syscall_get_arch() 342 - syscall_get_arguments() 343 - syscall_rollback() 344 - syscall_set_return_value() 345 - SIGSYS siginfo_t support 346 - secure_computing is called from a ptrace_event()-safe context 347 - secure_computing return value is checked and a return value of -1 348 results in the system call being skipped immediately. 349 - seccomp syscall wired up 350 351config SECCOMP_FILTER 352 def_bool y 353 depends on HAVE_ARCH_SECCOMP_FILTER && SECCOMP && NET 354 help 355 Enable tasks to build secure computing environments defined 356 in terms of Berkeley Packet Filter programs which implement 357 task-defined system call filtering polices. 358 359 See Documentation/prctl/seccomp_filter.txt for details. 360 361config HAVE_GCC_PLUGINS 362 bool 363 help 364 An arch should select this symbol if it supports building with 365 GCC plugins. 366 367menuconfig GCC_PLUGINS 368 bool "GCC plugins" 369 depends on HAVE_GCC_PLUGINS 370 depends on !COMPILE_TEST 371 help 372 GCC plugins are loadable modules that provide extra features to the 373 compiler. They are useful for runtime instrumentation and static analysis. 374 375 See Documentation/gcc-plugins.txt for details. 376 377config GCC_PLUGIN_CYC_COMPLEXITY 378 bool "Compute the cyclomatic complexity of a function" if EXPERT 379 depends on GCC_PLUGINS 380 depends on !COMPILE_TEST 381 help 382 The complexity M of a function's control flow graph is defined as: 383 M = E - N + 2P 384 where 385 386 E = the number of edges 387 N = the number of nodes 388 P = the number of connected components (exit nodes). 389 390 Enabling this plugin reports the complexity to stderr during the 391 build. It mainly serves as a simple example of how to create a 392 gcc plugin for the kernel. 393 394config GCC_PLUGIN_SANCOV 395 bool 396 depends on GCC_PLUGINS 397 help 398 This plugin inserts a __sanitizer_cov_trace_pc() call at the start of 399 basic blocks. It supports all gcc versions with plugin support (from 400 gcc-4.5 on). It is based on the commit "Add fuzzing coverage support" 401 by Dmitry Vyukov <dvyukov@google.com>. 402 403config GCC_PLUGIN_LATENT_ENTROPY 404 bool "Generate some entropy during boot and runtime" 405 depends on GCC_PLUGINS 406 help 407 By saying Y here the kernel will instrument some kernel code to 408 extract some entropy from both original and artificially created 409 program state. This will help especially embedded systems where 410 there is little 'natural' source of entropy normally. The cost 411 is some slowdown of the boot process (about 0.5%) and fork and 412 irq processing. 413 414 Note that entropy extracted this way is not cryptographically 415 secure! 416 417 This plugin was ported from grsecurity/PaX. More information at: 418 * https://grsecurity.net/ 419 * https://pax.grsecurity.net/ 420 421config GCC_PLUGIN_STRUCTLEAK 422 bool "Force initialization of variables containing userspace addresses" 423 depends on GCC_PLUGINS 424 help 425 This plugin zero-initializes any structures that containing a 426 __user attribute. This can prevent some classes of information 427 exposures. 428 429 This plugin was ported from grsecurity/PaX. More information at: 430 * https://grsecurity.net/ 431 * https://pax.grsecurity.net/ 432 433config GCC_PLUGIN_STRUCTLEAK_VERBOSE 434 bool "Report forcefully initialized variables" 435 depends on GCC_PLUGIN_STRUCTLEAK 436 depends on !COMPILE_TEST 437 help 438 This option will cause a warning to be printed each time the 439 structleak plugin finds a variable it thinks needs to be 440 initialized. Since not all existing initializers are detected 441 by the plugin, this can produce false positive warnings. 442 443config HAVE_CC_STACKPROTECTOR 444 bool 445 help 446 An arch should select this symbol if: 447 - its compiler supports the -fstack-protector option 448 - it has implemented a stack canary (e.g. __stack_chk_guard) 449 450config CC_STACKPROTECTOR 451 def_bool n 452 help 453 Set when a stack-protector mode is enabled, so that the build 454 can enable kernel-side support for the GCC feature. 455 456choice 457 prompt "Stack Protector buffer overflow detection" 458 depends on HAVE_CC_STACKPROTECTOR 459 default CC_STACKPROTECTOR_NONE 460 help 461 This option turns on the "stack-protector" GCC feature. This 462 feature puts, at the beginning of functions, a canary value on 463 the stack just before the return address, and validates 464 the value just before actually returning. Stack based buffer 465 overflows (that need to overwrite this return address) now also 466 overwrite the canary, which gets detected and the attack is then 467 neutralized via a kernel panic. 468 469config CC_STACKPROTECTOR_NONE 470 bool "None" 471 help 472 Disable "stack-protector" GCC feature. 473 474config CC_STACKPROTECTOR_REGULAR 475 bool "Regular" 476 select CC_STACKPROTECTOR 477 help 478 Functions will have the stack-protector canary logic added if they 479 have an 8-byte or larger character array on the stack. 480 481 This feature requires gcc version 4.2 or above, or a distribution 482 gcc with the feature backported ("-fstack-protector"). 483 484 On an x86 "defconfig" build, this feature adds canary checks to 485 about 3% of all kernel functions, which increases kernel code size 486 by about 0.3%. 487 488config CC_STACKPROTECTOR_STRONG 489 bool "Strong" 490 select CC_STACKPROTECTOR 491 help 492 Functions will have the stack-protector canary logic added in any 493 of the following conditions: 494 495 - local variable's address used as part of the right hand side of an 496 assignment or function argument 497 - local variable is an array (or union containing an array), 498 regardless of array type or length 499 - uses register local variables 500 501 This feature requires gcc version 4.9 or above, or a distribution 502 gcc with the feature backported ("-fstack-protector-strong"). 503 504 On an x86 "defconfig" build, this feature adds canary checks to 505 about 20% of all kernel functions, which increases the kernel code 506 size by about 2%. 507 508endchoice 509 510config THIN_ARCHIVES 511 bool 512 help 513 Select this if the architecture wants to use thin archives 514 instead of ld -r to create the built-in.o files. 515 516config LD_DEAD_CODE_DATA_ELIMINATION 517 bool 518 help 519 Select this if the architecture wants to do dead code and 520 data elimination with the linker by compiling with 521 -ffunction-sections -fdata-sections and linking with 522 --gc-sections. 523 524 This requires that the arch annotates or otherwise protects 525 its external entry points from being discarded. Linker scripts 526 must also merge .text.*, .data.*, and .bss.* correctly into 527 output sections. Care must be taken not to pull in unrelated 528 sections (e.g., '.text.init'). Typically '.' in section names 529 is used to distinguish them from label names / C identifiers. 530 531config HAVE_ARCH_WITHIN_STACK_FRAMES 532 bool 533 help 534 An architecture should select this if it can walk the kernel stack 535 frames to determine if an object is part of either the arguments 536 or local variables (i.e. that it excludes saved return addresses, 537 and similar) by implementing an inline arch_within_stack_frames(), 538 which is used by CONFIG_HARDENED_USERCOPY. 539 540config HAVE_CONTEXT_TRACKING 541 bool 542 help 543 Provide kernel/user boundaries probes necessary for subsystems 544 that need it, such as userspace RCU extended quiescent state. 545 Syscalls need to be wrapped inside user_exit()-user_enter() through 546 the slow path using TIF_NOHZ flag. Exceptions handlers must be 547 wrapped as well. Irqs are already protected inside 548 rcu_irq_enter/rcu_irq_exit() but preemption or signal handling on 549 irq exit still need to be protected. 550 551config HAVE_VIRT_CPU_ACCOUNTING 552 bool 553 554config ARCH_HAS_SCALED_CPUTIME 555 bool 556 557config HAVE_VIRT_CPU_ACCOUNTING_GEN 558 bool 559 default y if 64BIT 560 help 561 With VIRT_CPU_ACCOUNTING_GEN, cputime_t becomes 64-bit. 562 Before enabling this option, arch code must be audited 563 to ensure there are no races in concurrent read/write of 564 cputime_t. For example, reading/writing 64-bit cputime_t on 565 some 32-bit arches may require multiple accesses, so proper 566 locking is needed to protect against concurrent accesses. 567 568 569config HAVE_IRQ_TIME_ACCOUNTING 570 bool 571 help 572 Archs need to ensure they use a high enough resolution clock to 573 support irq time accounting and then call enable_sched_clock_irqtime(). 574 575config HAVE_ARCH_TRANSPARENT_HUGEPAGE 576 bool 577 578config HAVE_ARCH_TRANSPARENT_HUGEPAGE_PUD 579 bool 580 581config HAVE_ARCH_HUGE_VMAP 582 bool 583 584config HAVE_ARCH_SOFT_DIRTY 585 bool 586 587config HAVE_MOD_ARCH_SPECIFIC 588 bool 589 help 590 The arch uses struct mod_arch_specific to store data. Many arches 591 just need a simple module loader without arch specific data - those 592 should not enable this. 593 594config MODULES_USE_ELF_RELA 595 bool 596 help 597 Modules only use ELF RELA relocations. Modules with ELF REL 598 relocations will give an error. 599 600config MODULES_USE_ELF_REL 601 bool 602 help 603 Modules only use ELF REL relocations. Modules with ELF RELA 604 relocations will give an error. 605 606config HAVE_UNDERSCORE_SYMBOL_PREFIX 607 bool 608 help 609 Some architectures generate an _ in front of C symbols; things like 610 module loading and assembly files need to know about this. 611 612config HAVE_IRQ_EXIT_ON_IRQ_STACK 613 bool 614 help 615 Architecture doesn't only execute the irq handler on the irq stack 616 but also irq_exit(). This way we can process softirqs on this irq 617 stack instead of switching to a new one when we call __do_softirq() 618 in the end of an hardirq. 619 This spares a stack switch and improves cache usage on softirq 620 processing. 621 622config PGTABLE_LEVELS 623 int 624 default 2 625 626config ARCH_HAS_ELF_RANDOMIZE 627 bool 628 help 629 An architecture supports choosing randomized locations for 630 stack, mmap, brk, and ET_DYN. Defined functions: 631 - arch_mmap_rnd() 632 - arch_randomize_brk() 633 634config HAVE_ARCH_MMAP_RND_BITS 635 bool 636 help 637 An arch should select this symbol if it supports setting a variable 638 number of bits for use in establishing the base address for mmap 639 allocations, has MMU enabled and provides values for both: 640 - ARCH_MMAP_RND_BITS_MIN 641 - ARCH_MMAP_RND_BITS_MAX 642 643config HAVE_EXIT_THREAD 644 bool 645 help 646 An architecture implements exit_thread. 647 648config ARCH_MMAP_RND_BITS_MIN 649 int 650 651config ARCH_MMAP_RND_BITS_MAX 652 int 653 654config ARCH_MMAP_RND_BITS_DEFAULT 655 int 656 657config ARCH_MMAP_RND_BITS 658 int "Number of bits to use for ASLR of mmap base address" if EXPERT 659 range ARCH_MMAP_RND_BITS_MIN ARCH_MMAP_RND_BITS_MAX 660 default ARCH_MMAP_RND_BITS_DEFAULT if ARCH_MMAP_RND_BITS_DEFAULT 661 default ARCH_MMAP_RND_BITS_MIN 662 depends on HAVE_ARCH_MMAP_RND_BITS 663 help 664 This value can be used to select the number of bits to use to 665 determine the random offset to the base address of vma regions 666 resulting from mmap allocations. This value will be bounded 667 by the architecture's minimum and maximum supported values. 668 669 This value can be changed after boot using the 670 /proc/sys/vm/mmap_rnd_bits tunable 671 672config HAVE_ARCH_MMAP_RND_COMPAT_BITS 673 bool 674 help 675 An arch should select this symbol if it supports running applications 676 in compatibility mode, supports setting a variable number of bits for 677 use in establishing the base address for mmap allocations, has MMU 678 enabled and provides values for both: 679 - ARCH_MMAP_RND_COMPAT_BITS_MIN 680 - ARCH_MMAP_RND_COMPAT_BITS_MAX 681 682config ARCH_MMAP_RND_COMPAT_BITS_MIN 683 int 684 685config ARCH_MMAP_RND_COMPAT_BITS_MAX 686 int 687 688config ARCH_MMAP_RND_COMPAT_BITS_DEFAULT 689 int 690 691config ARCH_MMAP_RND_COMPAT_BITS 692 int "Number of bits to use for ASLR of mmap base address for compatible applications" if EXPERT 693 range ARCH_MMAP_RND_COMPAT_BITS_MIN ARCH_MMAP_RND_COMPAT_BITS_MAX 694 default ARCH_MMAP_RND_COMPAT_BITS_DEFAULT if ARCH_MMAP_RND_COMPAT_BITS_DEFAULT 695 default ARCH_MMAP_RND_COMPAT_BITS_MIN 696 depends on HAVE_ARCH_MMAP_RND_COMPAT_BITS 697 help 698 This value can be used to select the number of bits to use to 699 determine the random offset to the base address of vma regions 700 resulting from mmap allocations for compatible applications This 701 value will be bounded by the architecture's minimum and maximum 702 supported values. 703 704 This value can be changed after boot using the 705 /proc/sys/vm/mmap_rnd_compat_bits tunable 706 707config HAVE_ARCH_COMPAT_MMAP_BASES 708 bool 709 help 710 This allows 64bit applications to invoke 32-bit mmap() syscall 711 and vice-versa 32-bit applications to call 64-bit mmap(). 712 Required for applications doing different bitness syscalls. 713 714config HAVE_COPY_THREAD_TLS 715 bool 716 help 717 Architecture provides copy_thread_tls to accept tls argument via 718 normal C parameter passing, rather than extracting the syscall 719 argument from pt_regs. 720 721config HAVE_STACK_VALIDATION 722 bool 723 help 724 Architecture supports the 'objtool check' host tool command, which 725 performs compile-time stack metadata validation. 726 727config HAVE_RELIABLE_STACKTRACE 728 bool 729 help 730 Architecture has a save_stack_trace_tsk_reliable() function which 731 only returns a stack trace if it can guarantee the trace is reliable. 732 733config HAVE_ARCH_HASH 734 bool 735 default n 736 help 737 If this is set, the architecture provides an <asm/hash.h> 738 file which provides platform-specific implementations of some 739 functions in <linux/hash.h> or fs/namei.c. 740 741config ISA_BUS_API 742 def_bool ISA 743 744# 745# ABI hall of shame 746# 747config CLONE_BACKWARDS 748 bool 749 help 750 Architecture has tls passed as the 4th argument of clone(2), 751 not the 5th one. 752 753config CLONE_BACKWARDS2 754 bool 755 help 756 Architecture has the first two arguments of clone(2) swapped. 757 758config CLONE_BACKWARDS3 759 bool 760 help 761 Architecture has tls passed as the 3rd argument of clone(2), 762 not the 5th one. 763 764config ODD_RT_SIGACTION 765 bool 766 help 767 Architecture has unusual rt_sigaction(2) arguments 768 769config OLD_SIGSUSPEND 770 bool 771 help 772 Architecture has old sigsuspend(2) syscall, of one-argument variety 773 774config OLD_SIGSUSPEND3 775 bool 776 help 777 Even weirder antique ABI - three-argument sigsuspend(2) 778 779config OLD_SIGACTION 780 bool 781 help 782 Architecture has old sigaction(2) syscall. Nope, not the same 783 as OLD_SIGSUSPEND | OLD_SIGSUSPEND3 - alpha has sigsuspend(2), 784 but fairly different variant of sigaction(2), thanks to OSF/1 785 compatibility... 786 787config COMPAT_OLD_SIGACTION 788 bool 789 790config ARCH_NO_COHERENT_DMA_MMAP 791 bool 792 793config CPU_NO_EFFICIENT_FFS 794 def_bool n 795 796config HAVE_ARCH_VMAP_STACK 797 def_bool n 798 help 799 An arch should select this symbol if it can support kernel stacks 800 in vmalloc space. This means: 801 802 - vmalloc space must be large enough to hold many kernel stacks. 803 This may rule out many 32-bit architectures. 804 805 - Stacks in vmalloc space need to work reliably. For example, if 806 vmap page tables are created on demand, either this mechanism 807 needs to work while the stack points to a virtual address with 808 unpopulated page tables or arch code (switch_to() and switch_mm(), 809 most likely) needs to ensure that the stack's page table entries 810 are populated before running on a possibly unpopulated stack. 811 812 - If the stack overflows into a guard page, something reasonable 813 should happen. The definition of "reasonable" is flexible, but 814 instantly rebooting without logging anything would be unfriendly. 815 816config VMAP_STACK 817 default y 818 bool "Use a virtually-mapped stack" 819 depends on HAVE_ARCH_VMAP_STACK && !KASAN 820 ---help--- 821 Enable this if you want the use virtually-mapped kernel stacks 822 with guard pages. This causes kernel stack overflows to be 823 caught immediately rather than causing difficult-to-diagnose 824 corruption. 825 826 This is presently incompatible with KASAN because KASAN expects 827 the stack to map directly to the KASAN shadow map using a formula 828 that is incorrect if the stack is in vmalloc space. 829 830config ARCH_OPTIONAL_KERNEL_RWX 831 def_bool n 832 833config ARCH_OPTIONAL_KERNEL_RWX_DEFAULT 834 def_bool n 835 836config ARCH_HAS_STRICT_KERNEL_RWX 837 def_bool n 838 839config STRICT_KERNEL_RWX 840 bool "Make kernel text and rodata read-only" if ARCH_OPTIONAL_KERNEL_RWX 841 depends on ARCH_HAS_STRICT_KERNEL_RWX 842 default !ARCH_OPTIONAL_KERNEL_RWX || ARCH_OPTIONAL_KERNEL_RWX_DEFAULT 843 help 844 If this is set, kernel text and rodata memory will be made read-only, 845 and non-text memory will be made non-executable. This provides 846 protection against certain security exploits (e.g. executing the heap 847 or modifying text) 848 849 These features are considered standard security practice these days. 850 You should say Y here in almost all cases. 851 852config ARCH_HAS_STRICT_MODULE_RWX 853 def_bool n 854 855config STRICT_MODULE_RWX 856 bool "Set loadable kernel module data as NX and text as RO" if ARCH_OPTIONAL_KERNEL_RWX 857 depends on ARCH_HAS_STRICT_MODULE_RWX && MODULES 858 default !ARCH_OPTIONAL_KERNEL_RWX || ARCH_OPTIONAL_KERNEL_RWX_DEFAULT 859 help 860 If this is set, module text and rodata memory will be made read-only, 861 and non-text memory will be made non-executable. This provides 862 protection against certain security exploits (e.g. writing to text) 863 864config ARCH_WANT_RELAX_ORDER 865 bool 866 867source "kernel/gcov/Kconfig" 868