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_WEAK_RELEASE_ACQUIRE 328 bool 329 330config ARCH_WANT_IPC_PARSE_VERSION 331 bool 332 333config ARCH_WANT_COMPAT_IPC_PARSE_VERSION 334 bool 335 336config ARCH_WANT_OLD_COMPAT_IPC 337 select ARCH_WANT_COMPAT_IPC_PARSE_VERSION 338 bool 339 340config HAVE_ARCH_SECCOMP_FILTER 341 bool 342 help 343 An arch should select this symbol if it provides all of these things: 344 - syscall_get_arch() 345 - syscall_get_arguments() 346 - syscall_rollback() 347 - syscall_set_return_value() 348 - SIGSYS siginfo_t support 349 - secure_computing is called from a ptrace_event()-safe context 350 - secure_computing return value is checked and a return value of -1 351 results in the system call being skipped immediately. 352 - seccomp syscall wired up 353 354config SECCOMP_FILTER 355 def_bool y 356 depends on HAVE_ARCH_SECCOMP_FILTER && SECCOMP && NET 357 help 358 Enable tasks to build secure computing environments defined 359 in terms of Berkeley Packet Filter programs which implement 360 task-defined system call filtering polices. 361 362 See Documentation/prctl/seccomp_filter.txt for details. 363 364config HAVE_GCC_PLUGINS 365 bool 366 help 367 An arch should select this symbol if it supports building with 368 GCC plugins. 369 370menuconfig GCC_PLUGINS 371 bool "GCC plugins" 372 depends on HAVE_GCC_PLUGINS 373 depends on !COMPILE_TEST 374 help 375 GCC plugins are loadable modules that provide extra features to the 376 compiler. They are useful for runtime instrumentation and static analysis. 377 378 See Documentation/gcc-plugins.txt for details. 379 380config GCC_PLUGIN_CYC_COMPLEXITY 381 bool "Compute the cyclomatic complexity of a function" if EXPERT 382 depends on GCC_PLUGINS 383 depends on !COMPILE_TEST 384 help 385 The complexity M of a function's control flow graph is defined as: 386 M = E - N + 2P 387 where 388 389 E = the number of edges 390 N = the number of nodes 391 P = the number of connected components (exit nodes). 392 393 Enabling this plugin reports the complexity to stderr during the 394 build. It mainly serves as a simple example of how to create a 395 gcc plugin for the kernel. 396 397config GCC_PLUGIN_SANCOV 398 bool 399 depends on GCC_PLUGINS 400 help 401 This plugin inserts a __sanitizer_cov_trace_pc() call at the start of 402 basic blocks. It supports all gcc versions with plugin support (from 403 gcc-4.5 on). It is based on the commit "Add fuzzing coverage support" 404 by Dmitry Vyukov <dvyukov@google.com>. 405 406config GCC_PLUGIN_LATENT_ENTROPY 407 bool "Generate some entropy during boot and runtime" 408 depends on GCC_PLUGINS 409 help 410 By saying Y here the kernel will instrument some kernel code to 411 extract some entropy from both original and artificially created 412 program state. This will help especially embedded systems where 413 there is little 'natural' source of entropy normally. The cost 414 is some slowdown of the boot process (about 0.5%) and fork and 415 irq processing. 416 417 Note that entropy extracted this way is not cryptographically 418 secure! 419 420 This plugin was ported from grsecurity/PaX. More information at: 421 * https://grsecurity.net/ 422 * https://pax.grsecurity.net/ 423 424config GCC_PLUGIN_STRUCTLEAK 425 bool "Force initialization of variables containing userspace addresses" 426 depends on GCC_PLUGINS 427 help 428 This plugin zero-initializes any structures that containing a 429 __user attribute. This can prevent some classes of information 430 exposures. 431 432 This plugin was ported from grsecurity/PaX. More information at: 433 * https://grsecurity.net/ 434 * https://pax.grsecurity.net/ 435 436config GCC_PLUGIN_STRUCTLEAK_VERBOSE 437 bool "Report forcefully initialized variables" 438 depends on GCC_PLUGIN_STRUCTLEAK 439 depends on !COMPILE_TEST 440 help 441 This option will cause a warning to be printed each time the 442 structleak plugin finds a variable it thinks needs to be 443 initialized. Since not all existing initializers are detected 444 by the plugin, this can produce false positive warnings. 445 446config HAVE_CC_STACKPROTECTOR 447 bool 448 help 449 An arch should select this symbol if: 450 - its compiler supports the -fstack-protector option 451 - it has implemented a stack canary (e.g. __stack_chk_guard) 452 453config CC_STACKPROTECTOR 454 def_bool n 455 help 456 Set when a stack-protector mode is enabled, so that the build 457 can enable kernel-side support for the GCC feature. 458 459choice 460 prompt "Stack Protector buffer overflow detection" 461 depends on HAVE_CC_STACKPROTECTOR 462 default CC_STACKPROTECTOR_NONE 463 help 464 This option turns on the "stack-protector" GCC feature. This 465 feature puts, at the beginning of functions, a canary value on 466 the stack just before the return address, and validates 467 the value just before actually returning. Stack based buffer 468 overflows (that need to overwrite this return address) now also 469 overwrite the canary, which gets detected and the attack is then 470 neutralized via a kernel panic. 471 472config CC_STACKPROTECTOR_NONE 473 bool "None" 474 help 475 Disable "stack-protector" GCC feature. 476 477config CC_STACKPROTECTOR_REGULAR 478 bool "Regular" 479 select CC_STACKPROTECTOR 480 help 481 Functions will have the stack-protector canary logic added if they 482 have an 8-byte or larger character array on the stack. 483 484 This feature requires gcc version 4.2 or above, or a distribution 485 gcc with the feature backported ("-fstack-protector"). 486 487 On an x86 "defconfig" build, this feature adds canary checks to 488 about 3% of all kernel functions, which increases kernel code size 489 by about 0.3%. 490 491config CC_STACKPROTECTOR_STRONG 492 bool "Strong" 493 select CC_STACKPROTECTOR 494 help 495 Functions will have the stack-protector canary logic added in any 496 of the following conditions: 497 498 - local variable's address used as part of the right hand side of an 499 assignment or function argument 500 - local variable is an array (or union containing an array), 501 regardless of array type or length 502 - uses register local variables 503 504 This feature requires gcc version 4.9 or above, or a distribution 505 gcc with the feature backported ("-fstack-protector-strong"). 506 507 On an x86 "defconfig" build, this feature adds canary checks to 508 about 20% of all kernel functions, which increases the kernel code 509 size by about 2%. 510 511endchoice 512 513config THIN_ARCHIVES 514 bool 515 help 516 Select this if the architecture wants to use thin archives 517 instead of ld -r to create the built-in.o files. 518 519config LD_DEAD_CODE_DATA_ELIMINATION 520 bool 521 help 522 Select this if the architecture wants to do dead code and 523 data elimination with the linker by compiling with 524 -ffunction-sections -fdata-sections and linking with 525 --gc-sections. 526 527 This requires that the arch annotates or otherwise protects 528 its external entry points from being discarded. Linker scripts 529 must also merge .text.*, .data.*, and .bss.* correctly into 530 output sections. Care must be taken not to pull in unrelated 531 sections (e.g., '.text.init'). Typically '.' in section names 532 is used to distinguish them from label names / C identifiers. 533 534config HAVE_ARCH_WITHIN_STACK_FRAMES 535 bool 536 help 537 An architecture should select this if it can walk the kernel stack 538 frames to determine if an object is part of either the arguments 539 or local variables (i.e. that it excludes saved return addresses, 540 and similar) by implementing an inline arch_within_stack_frames(), 541 which is used by CONFIG_HARDENED_USERCOPY. 542 543config HAVE_CONTEXT_TRACKING 544 bool 545 help 546 Provide kernel/user boundaries probes necessary for subsystems 547 that need it, such as userspace RCU extended quiescent state. 548 Syscalls need to be wrapped inside user_exit()-user_enter() through 549 the slow path using TIF_NOHZ flag. Exceptions handlers must be 550 wrapped as well. Irqs are already protected inside 551 rcu_irq_enter/rcu_irq_exit() but preemption or signal handling on 552 irq exit still need to be protected. 553 554config HAVE_VIRT_CPU_ACCOUNTING 555 bool 556 557config ARCH_HAS_SCALED_CPUTIME 558 bool 559 560config HAVE_VIRT_CPU_ACCOUNTING_GEN 561 bool 562 default y if 64BIT 563 help 564 With VIRT_CPU_ACCOUNTING_GEN, cputime_t becomes 64-bit. 565 Before enabling this option, arch code must be audited 566 to ensure there are no races in concurrent read/write of 567 cputime_t. For example, reading/writing 64-bit cputime_t on 568 some 32-bit arches may require multiple accesses, so proper 569 locking is needed to protect against concurrent accesses. 570 571 572config HAVE_IRQ_TIME_ACCOUNTING 573 bool 574 help 575 Archs need to ensure they use a high enough resolution clock to 576 support irq time accounting and then call enable_sched_clock_irqtime(). 577 578config HAVE_ARCH_TRANSPARENT_HUGEPAGE 579 bool 580 581config HAVE_ARCH_TRANSPARENT_HUGEPAGE_PUD 582 bool 583 584config HAVE_ARCH_HUGE_VMAP 585 bool 586 587config HAVE_ARCH_SOFT_DIRTY 588 bool 589 590config HAVE_MOD_ARCH_SPECIFIC 591 bool 592 help 593 The arch uses struct mod_arch_specific to store data. Many arches 594 just need a simple module loader without arch specific data - those 595 should not enable this. 596 597config MODULES_USE_ELF_RELA 598 bool 599 help 600 Modules only use ELF RELA relocations. Modules with ELF REL 601 relocations will give an error. 602 603config MODULES_USE_ELF_REL 604 bool 605 help 606 Modules only use ELF REL relocations. Modules with ELF RELA 607 relocations will give an error. 608 609config HAVE_UNDERSCORE_SYMBOL_PREFIX 610 bool 611 help 612 Some architectures generate an _ in front of C symbols; things like 613 module loading and assembly files need to know about this. 614 615config HAVE_IRQ_EXIT_ON_IRQ_STACK 616 bool 617 help 618 Architecture doesn't only execute the irq handler on the irq stack 619 but also irq_exit(). This way we can process softirqs on this irq 620 stack instead of switching to a new one when we call __do_softirq() 621 in the end of an hardirq. 622 This spares a stack switch and improves cache usage on softirq 623 processing. 624 625config PGTABLE_LEVELS 626 int 627 default 2 628 629config ARCH_HAS_ELF_RANDOMIZE 630 bool 631 help 632 An architecture supports choosing randomized locations for 633 stack, mmap, brk, and ET_DYN. Defined functions: 634 - arch_mmap_rnd() 635 - arch_randomize_brk() 636 637config HAVE_ARCH_MMAP_RND_BITS 638 bool 639 help 640 An arch should select this symbol if it supports setting a variable 641 number of bits for use in establishing the base address for mmap 642 allocations, has MMU enabled and provides values for both: 643 - ARCH_MMAP_RND_BITS_MIN 644 - ARCH_MMAP_RND_BITS_MAX 645 646config HAVE_EXIT_THREAD 647 bool 648 help 649 An architecture implements exit_thread. 650 651config ARCH_MMAP_RND_BITS_MIN 652 int 653 654config ARCH_MMAP_RND_BITS_MAX 655 int 656 657config ARCH_MMAP_RND_BITS_DEFAULT 658 int 659 660config ARCH_MMAP_RND_BITS 661 int "Number of bits to use for ASLR of mmap base address" if EXPERT 662 range ARCH_MMAP_RND_BITS_MIN ARCH_MMAP_RND_BITS_MAX 663 default ARCH_MMAP_RND_BITS_DEFAULT if ARCH_MMAP_RND_BITS_DEFAULT 664 default ARCH_MMAP_RND_BITS_MIN 665 depends on HAVE_ARCH_MMAP_RND_BITS 666 help 667 This value can be used to select the number of bits to use to 668 determine the random offset to the base address of vma regions 669 resulting from mmap allocations. This value will be bounded 670 by the architecture's minimum and maximum supported values. 671 672 This value can be changed after boot using the 673 /proc/sys/vm/mmap_rnd_bits tunable 674 675config HAVE_ARCH_MMAP_RND_COMPAT_BITS 676 bool 677 help 678 An arch should select this symbol if it supports running applications 679 in compatibility mode, supports setting a variable number of bits for 680 use in establishing the base address for mmap allocations, has MMU 681 enabled and provides values for both: 682 - ARCH_MMAP_RND_COMPAT_BITS_MIN 683 - ARCH_MMAP_RND_COMPAT_BITS_MAX 684 685config ARCH_MMAP_RND_COMPAT_BITS_MIN 686 int 687 688config ARCH_MMAP_RND_COMPAT_BITS_MAX 689 int 690 691config ARCH_MMAP_RND_COMPAT_BITS_DEFAULT 692 int 693 694config ARCH_MMAP_RND_COMPAT_BITS 695 int "Number of bits to use for ASLR of mmap base address for compatible applications" if EXPERT 696 range ARCH_MMAP_RND_COMPAT_BITS_MIN ARCH_MMAP_RND_COMPAT_BITS_MAX 697 default ARCH_MMAP_RND_COMPAT_BITS_DEFAULT if ARCH_MMAP_RND_COMPAT_BITS_DEFAULT 698 default ARCH_MMAP_RND_COMPAT_BITS_MIN 699 depends on HAVE_ARCH_MMAP_RND_COMPAT_BITS 700 help 701 This value can be used to select the number of bits to use to 702 determine the random offset to the base address of vma regions 703 resulting from mmap allocations for compatible applications This 704 value will be bounded by the architecture's minimum and maximum 705 supported values. 706 707 This value can be changed after boot using the 708 /proc/sys/vm/mmap_rnd_compat_bits tunable 709 710config HAVE_ARCH_COMPAT_MMAP_BASES 711 bool 712 help 713 This allows 64bit applications to invoke 32-bit mmap() syscall 714 and vice-versa 32-bit applications to call 64-bit mmap(). 715 Required for applications doing different bitness syscalls. 716 717config HAVE_COPY_THREAD_TLS 718 bool 719 help 720 Architecture provides copy_thread_tls to accept tls argument via 721 normal C parameter passing, rather than extracting the syscall 722 argument from pt_regs. 723 724config HAVE_STACK_VALIDATION 725 bool 726 help 727 Architecture supports the 'objtool check' host tool command, which 728 performs compile-time stack metadata validation. 729 730config HAVE_RELIABLE_STACKTRACE 731 bool 732 help 733 Architecture has a save_stack_trace_tsk_reliable() function which 734 only returns a stack trace if it can guarantee the trace is reliable. 735 736config HAVE_ARCH_HASH 737 bool 738 default n 739 help 740 If this is set, the architecture provides an <asm/hash.h> 741 file which provides platform-specific implementations of some 742 functions in <linux/hash.h> or fs/namei.c. 743 744config ISA_BUS_API 745 def_bool ISA 746 747# 748# ABI hall of shame 749# 750config CLONE_BACKWARDS 751 bool 752 help 753 Architecture has tls passed as the 4th argument of clone(2), 754 not the 5th one. 755 756config CLONE_BACKWARDS2 757 bool 758 help 759 Architecture has the first two arguments of clone(2) swapped. 760 761config CLONE_BACKWARDS3 762 bool 763 help 764 Architecture has tls passed as the 3rd argument of clone(2), 765 not the 5th one. 766 767config ODD_RT_SIGACTION 768 bool 769 help 770 Architecture has unusual rt_sigaction(2) arguments 771 772config OLD_SIGSUSPEND 773 bool 774 help 775 Architecture has old sigsuspend(2) syscall, of one-argument variety 776 777config OLD_SIGSUSPEND3 778 bool 779 help 780 Even weirder antique ABI - three-argument sigsuspend(2) 781 782config OLD_SIGACTION 783 bool 784 help 785 Architecture has old sigaction(2) syscall. Nope, not the same 786 as OLD_SIGSUSPEND | OLD_SIGSUSPEND3 - alpha has sigsuspend(2), 787 but fairly different variant of sigaction(2), thanks to OSF/1 788 compatibility... 789 790config COMPAT_OLD_SIGACTION 791 bool 792 793config ARCH_NO_COHERENT_DMA_MMAP 794 bool 795 796config CPU_NO_EFFICIENT_FFS 797 def_bool n 798 799config HAVE_ARCH_VMAP_STACK 800 def_bool n 801 help 802 An arch should select this symbol if it can support kernel stacks 803 in vmalloc space. This means: 804 805 - vmalloc space must be large enough to hold many kernel stacks. 806 This may rule out many 32-bit architectures. 807 808 - Stacks in vmalloc space need to work reliably. For example, if 809 vmap page tables are created on demand, either this mechanism 810 needs to work while the stack points to a virtual address with 811 unpopulated page tables or arch code (switch_to() and switch_mm(), 812 most likely) needs to ensure that the stack's page table entries 813 are populated before running on a possibly unpopulated stack. 814 815 - If the stack overflows into a guard page, something reasonable 816 should happen. The definition of "reasonable" is flexible, but 817 instantly rebooting without logging anything would be unfriendly. 818 819config VMAP_STACK 820 default y 821 bool "Use a virtually-mapped stack" 822 depends on HAVE_ARCH_VMAP_STACK && !KASAN 823 ---help--- 824 Enable this if you want the use virtually-mapped kernel stacks 825 with guard pages. This causes kernel stack overflows to be 826 caught immediately rather than causing difficult-to-diagnose 827 corruption. 828 829 This is presently incompatible with KASAN because KASAN expects 830 the stack to map directly to the KASAN shadow map using a formula 831 that is incorrect if the stack is in vmalloc space. 832 833config ARCH_OPTIONAL_KERNEL_RWX 834 def_bool n 835 836config ARCH_OPTIONAL_KERNEL_RWX_DEFAULT 837 def_bool n 838 839config ARCH_HAS_STRICT_KERNEL_RWX 840 def_bool n 841 842config STRICT_KERNEL_RWX 843 bool "Make kernel text and rodata read-only" if ARCH_OPTIONAL_KERNEL_RWX 844 depends on ARCH_HAS_STRICT_KERNEL_RWX 845 default !ARCH_OPTIONAL_KERNEL_RWX || ARCH_OPTIONAL_KERNEL_RWX_DEFAULT 846 help 847 If this is set, kernel text and rodata memory will be made read-only, 848 and non-text memory will be made non-executable. This provides 849 protection against certain security exploits (e.g. executing the heap 850 or modifying text) 851 852 These features are considered standard security practice these days. 853 You should say Y here in almost all cases. 854 855config ARCH_HAS_STRICT_MODULE_RWX 856 def_bool n 857 858config STRICT_MODULE_RWX 859 bool "Set loadable kernel module data as NX and text as RO" if ARCH_OPTIONAL_KERNEL_RWX 860 depends on ARCH_HAS_STRICT_MODULE_RWX && MODULES 861 default !ARCH_OPTIONAL_KERNEL_RWX || ARCH_OPTIONAL_KERNEL_RWX_DEFAULT 862 help 863 If this is set, module text and rodata memory will be made read-only, 864 and non-text memory will be made non-executable. This provides 865 protection against certain security exploits (e.g. writing to text) 866 867config ARCH_WANT_RELAX_ORDER 868 bool 869 870source "kernel/gcov/Kconfig" 871