1b2441318SGreg Kroah-Hartman# SPDX-License-Identifier: GPL-2.0 2fb32e03fSMathieu Desnoyers# 3fb32e03fSMathieu Desnoyers# General architecture dependent options 4fb32e03fSMathieu Desnoyers# 5125e5645SMathieu Desnoyers 61572497cSChristoph Hellwig# 71572497cSChristoph Hellwig# Note: arch/$(SRCARCH)/Kconfig needs to be included first so that it can 81572497cSChristoph Hellwig# override the default values in this file. 91572497cSChristoph Hellwig# 101572497cSChristoph Hellwigsource "arch/$(SRCARCH)/Kconfig" 111572497cSChristoph Hellwig 1222471e13SRandy Dunlapmenu "General architecture-dependent options" 1322471e13SRandy Dunlap 14692f66f2SHari Bathiniconfig CRASH_CORE 15692f66f2SHari Bathini bool 16692f66f2SHari Bathini 172965faa5SDave Youngconfig KEXEC_CORE 18692f66f2SHari Bathini select CRASH_CORE 192965faa5SDave Young bool 202965faa5SDave Young 21175fca3bSSven Schnelleconfig KEXEC_ELF 22175fca3bSSven Schnelle bool 23175fca3bSSven Schnelle 24467d2782SThiago Jung Bauermannconfig HAVE_IMA_KEXEC 25467d2782SThiago Jung Bauermann bool 26467d2782SThiago Jung Bauermann 275e6e9852SChristoph Hellwigconfig SET_FS 285e6e9852SChristoph Hellwig bool 295e6e9852SChristoph Hellwig 3005736e4aSThomas Gleixnerconfig HOTPLUG_SMT 3105736e4aSThomas Gleixner bool 3205736e4aSThomas Gleixner 33142781e1SThomas Gleixnerconfig GENERIC_ENTRY 34142781e1SThomas Gleixner bool 35142781e1SThomas Gleixner 36125e5645SMathieu Desnoyersconfig KPROBES 37125e5645SMathieu Desnoyers bool "Kprobes" 3805ed160eSMasami Hiramatsu depends on MODULES 39125e5645SMathieu Desnoyers depends on HAVE_KPROBES 4005ed160eSMasami Hiramatsu select KALLSYMS 41125e5645SMathieu Desnoyers help 42125e5645SMathieu Desnoyers Kprobes allows you to trap at almost any kernel address and 43125e5645SMathieu Desnoyers execute a callback function. register_kprobe() establishes 44125e5645SMathieu Desnoyers a probepoint and specifies the callback. Kprobes is useful 45125e5645SMathieu Desnoyers for kernel debugging, non-intrusive instrumentation and testing. 46125e5645SMathieu Desnoyers If in doubt, say "N". 47125e5645SMathieu Desnoyers 4845f81b1cSSteven Rostedtconfig JUMP_LABEL 49c5905afbSIngo Molnar bool "Optimize very unlikely/likely branches" 5045f81b1cSSteven Rostedt depends on HAVE_ARCH_JUMP_LABEL 51e9666d10SMasahiro Yamada depends on CC_HAS_ASM_GOTO 5245f81b1cSSteven Rostedt help 53c5905afbSIngo Molnar This option enables a transparent branch optimization that 54c5905afbSIngo Molnar makes certain almost-always-true or almost-always-false branch 55c5905afbSIngo Molnar conditions even cheaper to execute within the kernel. 5645f81b1cSSteven Rostedt 57c5905afbSIngo Molnar Certain performance-sensitive kernel code, such as trace points, 58c5905afbSIngo Molnar scheduler functionality, networking code and KVM have such 59c5905afbSIngo Molnar branches and include support for this optimization technique. 60c5905afbSIngo Molnar 61c5905afbSIngo Molnar If it is detected that the compiler has support for "asm goto", 62c5905afbSIngo Molnar the kernel will compile such branches with just a nop 63c5905afbSIngo Molnar instruction. When the condition flag is toggled to true, the 64c5905afbSIngo Molnar nop will be converted to a jump instruction to execute the 65c5905afbSIngo Molnar conditional block of instructions. 66c5905afbSIngo Molnar 67c5905afbSIngo Molnar This technique lowers overhead and stress on the branch prediction 68c5905afbSIngo Molnar of the processor and generally makes the kernel faster. The update 69c5905afbSIngo Molnar of the condition is slower, but those are always very rare. 70c5905afbSIngo Molnar 71c5905afbSIngo Molnar ( On 32-bit x86, the necessary options added to the compiler 72c5905afbSIngo Molnar flags may increase the size of the kernel slightly. ) 7345f81b1cSSteven Rostedt 741987c947SPeter Zijlstraconfig STATIC_KEYS_SELFTEST 751987c947SPeter Zijlstra bool "Static key selftest" 761987c947SPeter Zijlstra depends on JUMP_LABEL 771987c947SPeter Zijlstra help 781987c947SPeter Zijlstra Boot time self-test of the branch patching code. 791987c947SPeter Zijlstra 80f03c4129SPeter Zijlstraconfig STATIC_CALL_SELFTEST 81f03c4129SPeter Zijlstra bool "Static call selftest" 82f03c4129SPeter Zijlstra depends on HAVE_STATIC_CALL 83f03c4129SPeter Zijlstra help 84f03c4129SPeter Zijlstra Boot time self-test of the call patching code. 85f03c4129SPeter Zijlstra 86afd66255SMasami Hiramatsuconfig OPTPROBES 875cc718b9SMasami Hiramatsu def_bool y 885cc718b9SMasami Hiramatsu depends on KPROBES && HAVE_OPTPROBES 8901b1d88bSThomas Gleixner select TASKS_RCU if PREEMPTION 90afd66255SMasami Hiramatsu 91e7dbfe34SMasami Hiramatsuconfig KPROBES_ON_FTRACE 92e7dbfe34SMasami Hiramatsu def_bool y 93e7dbfe34SMasami Hiramatsu depends on KPROBES && HAVE_KPROBES_ON_FTRACE 94e7dbfe34SMasami Hiramatsu depends on DYNAMIC_FTRACE_WITH_REGS 95e7dbfe34SMasami Hiramatsu help 96e7dbfe34SMasami Hiramatsu If function tracer is enabled and the arch supports full 97e7dbfe34SMasami Hiramatsu passing of pt_regs to function tracing, then kprobes can 98e7dbfe34SMasami Hiramatsu optimize on top of function tracing. 99e7dbfe34SMasami Hiramatsu 1002b144498SSrikar Dronamrajuconfig UPROBES 10109294e31SDavid A. Long def_bool n 102e8f4aa60SAllen Pais depends on ARCH_SUPPORTS_UPROBES 1032b144498SSrikar Dronamraju help 1047b2d81d4SIngo Molnar Uprobes is the user-space counterpart to kprobes: they 1057b2d81d4SIngo Molnar enable instrumentation applications (such as 'perf probe') 1067b2d81d4SIngo Molnar to establish unintrusive probes in user-space binaries and 1077b2d81d4SIngo Molnar libraries, by executing handler functions when the probes 1087b2d81d4SIngo Molnar are hit by user-space applications. 1097b2d81d4SIngo Molnar 1107b2d81d4SIngo Molnar ( These probes come in the form of single-byte breakpoints, 1117b2d81d4SIngo Molnar managed by the kernel and kept transparent to the probed 1127b2d81d4SIngo Molnar application. ) 1132b144498SSrikar Dronamraju 114adab66b7SSteven Rostedt (VMware)config HAVE_64BIT_ALIGNED_ACCESS 115adab66b7SSteven Rostedt (VMware) def_bool 64BIT && !HAVE_EFFICIENT_UNALIGNED_ACCESS 116adab66b7SSteven Rostedt (VMware) help 117adab66b7SSteven Rostedt (VMware) Some architectures require 64 bit accesses to be 64 bit 118adab66b7SSteven Rostedt (VMware) aligned, which also requires structs containing 64 bit values 119adab66b7SSteven Rostedt (VMware) to be 64 bit aligned too. This includes some 32 bit 120adab66b7SSteven Rostedt (VMware) architectures which can do 64 bit accesses, as well as 64 bit 121adab66b7SSteven Rostedt (VMware) architectures without unaligned access. 122adab66b7SSteven Rostedt (VMware) 123adab66b7SSteven Rostedt (VMware) This symbol should be selected by an architecture if 64 bit 124adab66b7SSteven Rostedt (VMware) accesses are required to be 64 bit aligned in this way even 125adab66b7SSteven Rostedt (VMware) though it is not a 64 bit architecture. 126adab66b7SSteven Rostedt (VMware) 127ba1a297dSLukas Bulwahn See Documentation/core-api/unaligned-memory-access.rst for 128ba1a297dSLukas Bulwahn more information on the topic of unaligned memory accesses. 129adab66b7SSteven Rostedt (VMware) 13058340a07SJohannes Bergconfig HAVE_EFFICIENT_UNALIGNED_ACCESS 1319ba16087SJan Beulich bool 13258340a07SJohannes Berg help 13358340a07SJohannes Berg Some architectures are unable to perform unaligned accesses 13458340a07SJohannes Berg without the use of get_unaligned/put_unaligned. Others are 13558340a07SJohannes Berg unable to perform such accesses efficiently (e.g. trap on 13658340a07SJohannes Berg unaligned access and require fixing it up in the exception 13758340a07SJohannes Berg handler.) 13858340a07SJohannes Berg 13958340a07SJohannes Berg This symbol should be selected by an architecture if it can 14058340a07SJohannes Berg perform unaligned accesses efficiently to allow different 14158340a07SJohannes Berg code paths to be selected for these cases. Some network 14258340a07SJohannes Berg drivers, for example, could opt to not fix up alignment 14358340a07SJohannes Berg problems with received packets if doing so would not help 14458340a07SJohannes Berg much. 14558340a07SJohannes Berg 146c9b54d6fSMauro Carvalho Chehab See Documentation/core-api/unaligned-memory-access.rst for more 14758340a07SJohannes Berg information on the topic of unaligned memory accesses. 14858340a07SJohannes Berg 149cf66bb93SDavid Woodhouseconfig ARCH_USE_BUILTIN_BSWAP 150cf66bb93SDavid Woodhouse bool 151cf66bb93SDavid Woodhouse help 152cf66bb93SDavid Woodhouse Modern versions of GCC (since 4.4) have builtin functions 153cf66bb93SDavid Woodhouse for handling byte-swapping. Using these, instead of the old 154cf66bb93SDavid Woodhouse inline assembler that the architecture code provides in the 155cf66bb93SDavid Woodhouse __arch_bswapXX() macros, allows the compiler to see what's 156cf66bb93SDavid Woodhouse happening and offers more opportunity for optimisation. In 157cf66bb93SDavid Woodhouse particular, the compiler will be able to combine the byteswap 158cf66bb93SDavid Woodhouse with a nearby load or store and use load-and-swap or 159cf66bb93SDavid Woodhouse store-and-swap instructions if the architecture has them. It 160cf66bb93SDavid Woodhouse should almost *never* result in code which is worse than the 161cf66bb93SDavid Woodhouse hand-coded assembler in <asm/swab.h>. But just in case it 162cf66bb93SDavid Woodhouse does, the use of the builtins is optional. 163cf66bb93SDavid Woodhouse 164cf66bb93SDavid Woodhouse Any architecture with load-and-swap or store-and-swap 165cf66bb93SDavid Woodhouse instructions should set this. And it shouldn't hurt to set it 166cf66bb93SDavid Woodhouse on architectures that don't have such instructions. 167cf66bb93SDavid Woodhouse 1689edddaa2SAnanth N Mavinakayanahalliconfig KRETPROBES 1699edddaa2SAnanth N Mavinakayanahalli def_bool y 1709edddaa2SAnanth N Mavinakayanahalli depends on KPROBES && HAVE_KRETPROBES 1719edddaa2SAnanth N Mavinakayanahalli 1727c68af6eSAvi Kivityconfig USER_RETURN_NOTIFIER 1737c68af6eSAvi Kivity bool 1747c68af6eSAvi Kivity depends on HAVE_USER_RETURN_NOTIFIER 1757c68af6eSAvi Kivity help 1767c68af6eSAvi Kivity Provide a kernel-internal notification when a cpu is about to 1777c68af6eSAvi Kivity switch to user mode. 1787c68af6eSAvi Kivity 17928b2ee20SRik van Rielconfig HAVE_IOREMAP_PROT 1809ba16087SJan Beulich bool 18128b2ee20SRik van Riel 182125e5645SMathieu Desnoyersconfig HAVE_KPROBES 1839ba16087SJan Beulich bool 1849edddaa2SAnanth N Mavinakayanahalli 1859edddaa2SAnanth N Mavinakayanahalliconfig HAVE_KRETPROBES 1869ba16087SJan Beulich bool 18774bc7ceeSArthur Kepner 188afd66255SMasami Hiramatsuconfig HAVE_OPTPROBES 189afd66255SMasami Hiramatsu bool 190d314d74cSCong Wang 191e7dbfe34SMasami Hiramatsuconfig HAVE_KPROBES_ON_FTRACE 192e7dbfe34SMasami Hiramatsu bool 193e7dbfe34SMasami Hiramatsu 1941f6d3a8fSMasami Hiramatsuconfig ARCH_CORRECT_STACKTRACE_ON_KRETPROBE 1951f6d3a8fSMasami Hiramatsu bool 1961f6d3a8fSMasami Hiramatsu help 1971f6d3a8fSMasami Hiramatsu Since kretprobes modifies return address on the stack, the 1981f6d3a8fSMasami Hiramatsu stacktrace may see the kretprobe trampoline address instead 1991f6d3a8fSMasami Hiramatsu of correct one. If the architecture stacktrace code and 2001f6d3a8fSMasami Hiramatsu unwinder can adjust such entries, select this configuration. 2011f6d3a8fSMasami Hiramatsu 202540adea3SMasami Hiramatsuconfig HAVE_FUNCTION_ERROR_INJECTION 2039802d865SJosef Bacik bool 2049802d865SJosef Bacik 20542a0bb3fSPetr Mladekconfig HAVE_NMI 20642a0bb3fSPetr Mladek bool 20742a0bb3fSPetr Mladek 2084aae683fSMasahiro Yamadaconfig TRACE_IRQFLAGS_SUPPORT 2094aae683fSMasahiro Yamada bool 2104aae683fSMasahiro Yamada 2111f5a4ad9SRoland McGrath# 2121f5a4ad9SRoland McGrath# An arch should select this if it provides all these things: 2131f5a4ad9SRoland McGrath# 2141f5a4ad9SRoland McGrath# task_pt_regs() in asm/processor.h or asm/ptrace.h 2151f5a4ad9SRoland McGrath# arch_has_single_step() if there is hardware single-step support 2161f5a4ad9SRoland McGrath# arch_has_block_step() if there is hardware block-step support 2171f5a4ad9SRoland McGrath# asm/syscall.h supplying asm-generic/syscall.h interface 2181f5a4ad9SRoland McGrath# linux/regset.h user_regset interfaces 2191f5a4ad9SRoland McGrath# CORE_DUMP_USE_REGSET #define'd in linux/elf.h 2201f5a4ad9SRoland McGrath# TIF_SYSCALL_TRACE calls tracehook_report_syscall_{entry,exit} 2211f5a4ad9SRoland McGrath# TIF_NOTIFY_RESUME calls tracehook_notify_resume() 2221f5a4ad9SRoland McGrath# signal delivery calls tracehook_signal_handler() 2231f5a4ad9SRoland McGrath# 2241f5a4ad9SRoland McGrathconfig HAVE_ARCH_TRACEHOOK 2259ba16087SJan Beulich bool 2261f5a4ad9SRoland McGrath 227c64be2bbSMarek Szyprowskiconfig HAVE_DMA_CONTIGUOUS 228c64be2bbSMarek Szyprowski bool 229c64be2bbSMarek Szyprowski 23029d5e047SThomas Gleixnerconfig GENERIC_SMP_IDLE_THREAD 23129d5e047SThomas Gleixner bool 23229d5e047SThomas Gleixner 233485cf5daSKevin Hilmanconfig GENERIC_IDLE_POLL_SETUP 234485cf5daSKevin Hilman bool 235485cf5daSKevin Hilman 2366974f0c4SDaniel Micayconfig ARCH_HAS_FORTIFY_SOURCE 2376974f0c4SDaniel Micay bool 2386974f0c4SDaniel Micay help 2396974f0c4SDaniel Micay An architecture should select this when it can successfully 2406974f0c4SDaniel Micay build and run with CONFIG_FORTIFY_SOURCE. 2416974f0c4SDaniel Micay 242d8ae8a37SChristoph Hellwig# 243d8ae8a37SChristoph Hellwig# Select if the arch provides a historic keepinit alias for the retain_initrd 244d8ae8a37SChristoph Hellwig# command line option 245d8ae8a37SChristoph Hellwig# 246d8ae8a37SChristoph Hellwigconfig ARCH_HAS_KEEPINITRD 247d8ae8a37SChristoph Hellwig bool 248d8ae8a37SChristoph Hellwig 249d2852a22SDaniel Borkmann# Select if arch has all set_memory_ro/rw/x/nx() functions in asm/cacheflush.h 250d2852a22SDaniel Borkmannconfig ARCH_HAS_SET_MEMORY 251d2852a22SDaniel Borkmann bool 252d2852a22SDaniel Borkmann 253d253ca0cSRick Edgecombe# Select if arch has all set_direct_map_invalid/default() functions 254d253ca0cSRick Edgecombeconfig ARCH_HAS_SET_DIRECT_MAP 255d253ca0cSRick Edgecombe bool 256d253ca0cSRick Edgecombe 257c30700dbSChristoph Hellwig# 258fa7e2247SChristoph Hellwig# Select if the architecture provides the arch_dma_set_uncached symbol to 259a86ecfa6SColin Ian King# either provide an uncached segment alias for a DMA allocation, or 260fa7e2247SChristoph Hellwig# to remap the page tables in place. 261c30700dbSChristoph Hellwig# 262fa7e2247SChristoph Hellwigconfig ARCH_HAS_DMA_SET_UNCACHED 263c30700dbSChristoph Hellwig bool 264c30700dbSChristoph Hellwig 265999a5d12SChristoph Hellwig# 266999a5d12SChristoph Hellwig# Select if the architectures provides the arch_dma_clear_uncached symbol 267999a5d12SChristoph Hellwig# to undo an in-place page table remap for uncached access. 268999a5d12SChristoph Hellwig# 269999a5d12SChristoph Hellwigconfig ARCH_HAS_DMA_CLEAR_UNCACHED 270f5e10287SThomas Gleixner bool 271f5e10287SThomas Gleixner 2725905429aSKees Cook# Select if arch init_task must go in the __init_task_data section 2735905429aSKees Cookconfig ARCH_TASK_STRUCT_ON_STACK 2745905429aSKees Cook bool 2755905429aSKees Cook 2765905429aSKees Cook# Select if arch has its private alloc_task_struct() function 2775905429aSKees Cookconfig ARCH_TASK_STRUCT_ALLOCATOR 2785905429aSKees Cook bool 2795905429aSKees Cook 2805905429aSKees Cookconfig HAVE_ARCH_THREAD_STRUCT_WHITELIST 2815905429aSKees Cook bool 2825905429aSKees Cook depends on !ARCH_TASK_STRUCT_ALLOCATOR 283b235beeaSLinus Torvalds help 284b235beeaSLinus Torvalds An architecture should select this to provide hardened usercopy 285f5e10287SThomas Gleixner knowledge about what region of the thread_struct should be 286f5e10287SThomas Gleixner whitelisted for copying to userspace. Normally this is only the 2875aaeb5c0SIngo Molnar FPU registers. Specifically, arch_thread_struct_whitelist() 2885aaeb5c0SIngo Molnar should be implemented. Without this, the entire thread_struct 2895aaeb5c0SIngo Molnar field in task_struct will be left whitelisted. 2905aaeb5c0SIngo Molnar 291942fa985SYury Norov# Select if arch has its private alloc_thread_stack() function 292942fa985SYury Norovconfig ARCH_THREAD_STACK_ALLOCATOR 293942fa985SYury Norov bool 294942fa985SYury Norov 295942fa985SYury Norov# Select if arch wants to size task_struct dynamically via arch_task_struct_size: 296942fa985SYury Norovconfig ARCH_WANTS_DYNAMIC_TASK_STRUCT 297942fa985SYury Norov bool 298942fa985SYury Norov 29951c2ee6dSNick Desaulniersconfig ARCH_WANTS_NO_INSTR 30051c2ee6dSNick Desaulniers bool 30151c2ee6dSNick Desaulniers help 30251c2ee6dSNick Desaulniers An architecture should select this if the noinstr macro is being used on 30351c2ee6dSNick Desaulniers functions to denote that the toolchain should avoid instrumenting such 30451c2ee6dSNick Desaulniers functions and is required for correctness. 30551c2ee6dSNick Desaulniers 306942fa985SYury Norovconfig ARCH_32BIT_OFF_T 307942fa985SYury Norov bool 308942fa985SYury Norov depends on !64BIT 309942fa985SYury Norov help 310942fa985SYury Norov All new 32-bit architectures should have 64-bit off_t type on 311942fa985SYury Norov userspace side which corresponds to the loff_t kernel type. This 312942fa985SYury Norov is the requirement for modern ABIs. Some existing architectures 313942fa985SYury Norov still support 32-bit off_t. This option is enabled for all such 314942fa985SYury Norov architectures explicitly. 315942fa985SYury Norov 31696c0a6a7SHeiko Carstens# Selected by 64 bit architectures which have a 32 bit f_tinode in struct ustat 31796c0a6a7SHeiko Carstensconfig ARCH_32BIT_USTAT_F_TINODE 31896c0a6a7SHeiko Carstens bool 31996c0a6a7SHeiko Carstens 3202ff2b7ecSMasahiro Yamadaconfig HAVE_ASM_MODVERSIONS 3212ff2b7ecSMasahiro Yamada bool 3222ff2b7ecSMasahiro Yamada help 323a86ecfa6SColin Ian King This symbol should be selected by an architecture if it provides 3242ff2b7ecSMasahiro Yamada <asm/asm-prototypes.h> to support the module versioning for symbols 3252ff2b7ecSMasahiro Yamada exported from assembly code. 3262ff2b7ecSMasahiro Yamada 327f850c30cSHeiko Carstensconfig HAVE_REGS_AND_STACK_ACCESS_API 328f850c30cSHeiko Carstens bool 329e01292b1SHeiko Carstens help 330a86ecfa6SColin Ian King This symbol should be selected by an architecture if it supports 331e01292b1SHeiko Carstens the API needed to access registers and stack entries from pt_regs, 332e01292b1SHeiko Carstens declared in asm/ptrace.h 333e01292b1SHeiko Carstens For example the kprobes-based event tracer needs this API. 334f850c30cSHeiko Carstens 335d7822b1eSMathieu Desnoyersconfig HAVE_RSEQ 336d7822b1eSMathieu Desnoyers bool 337d7822b1eSMathieu Desnoyers depends on HAVE_REGS_AND_STACK_ACCESS_API 338d7822b1eSMathieu Desnoyers help 339d7822b1eSMathieu Desnoyers This symbol should be selected by an architecture if it 340d7822b1eSMathieu Desnoyers supports an implementation of restartable sequences. 341d7822b1eSMathieu Desnoyers 3423c88ee19SMasami Hiramatsuconfig HAVE_FUNCTION_ARG_ACCESS_API 3433c88ee19SMasami Hiramatsu bool 3443c88ee19SMasami Hiramatsu help 345a86ecfa6SColin Ian King This symbol should be selected by an architecture if it supports 3463c88ee19SMasami Hiramatsu the API needed to access function arguments from pt_regs, 3473c88ee19SMasami Hiramatsu declared in asm/ptrace.h 3483c88ee19SMasami Hiramatsu 34962a038d3SK.Prasadconfig HAVE_HW_BREAKPOINT 35062a038d3SK.Prasad bool 35199e8c5a3SFrederic Weisbecker depends on PERF_EVENTS 35262a038d3SK.Prasad 3530102752eSFrederic Weisbeckerconfig HAVE_MIXED_BREAKPOINTS_REGS 3540102752eSFrederic Weisbecker bool 3550102752eSFrederic Weisbecker depends on HAVE_HW_BREAKPOINT 3560102752eSFrederic Weisbecker help 3570102752eSFrederic Weisbecker Depending on the arch implementation of hardware breakpoints, 3580102752eSFrederic Weisbecker some of them have separate registers for data and instruction 3590102752eSFrederic Weisbecker breakpoints addresses, others have mixed registers to store 3600102752eSFrederic Weisbecker them but define the access type in a control register. 3610102752eSFrederic Weisbecker Select this option if your arch implements breakpoints under the 3620102752eSFrederic Weisbecker latter fashion. 3630102752eSFrederic Weisbecker 3647c68af6eSAvi Kivityconfig HAVE_USER_RETURN_NOTIFIER 3657c68af6eSAvi Kivity bool 366a1922ed6SIngo Molnar 367c01d4323SFrederic Weisbeckerconfig HAVE_PERF_EVENTS_NMI 368c01d4323SFrederic Weisbecker bool 36923637d47SFrederic Weisbecker help 37023637d47SFrederic Weisbecker System hardware can generate an NMI using the perf event 37123637d47SFrederic Weisbecker subsystem. Also has support for calculating CPU cycle events 37223637d47SFrederic Weisbecker to determine how many clock cycles in a given period. 373c01d4323SFrederic Weisbecker 37405a4a952SNicholas Pigginconfig HAVE_HARDLOCKUP_DETECTOR_PERF 37505a4a952SNicholas Piggin bool 37605a4a952SNicholas Piggin depends on HAVE_PERF_EVENTS_NMI 37705a4a952SNicholas Piggin help 37805a4a952SNicholas Piggin The arch chooses to use the generic perf-NMI-based hardlockup 37905a4a952SNicholas Piggin detector. Must define HAVE_PERF_EVENTS_NMI. 38005a4a952SNicholas Piggin 38105a4a952SNicholas Pigginconfig HAVE_NMI_WATCHDOG 38205a4a952SNicholas Piggin depends on HAVE_NMI 38305a4a952SNicholas Piggin bool 38405a4a952SNicholas Piggin help 38505a4a952SNicholas Piggin The arch provides a low level NMI watchdog. It provides 38605a4a952SNicholas Piggin asm/nmi.h, and defines its own arch_touch_nmi_watchdog(). 38705a4a952SNicholas Piggin 38805a4a952SNicholas Pigginconfig HAVE_HARDLOCKUP_DETECTOR_ARCH 38905a4a952SNicholas Piggin bool 39005a4a952SNicholas Piggin select HAVE_NMI_WATCHDOG 39105a4a952SNicholas Piggin help 39205a4a952SNicholas Piggin The arch chooses to provide its own hardlockup detector, which is 39305a4a952SNicholas Piggin a superset of the HAVE_NMI_WATCHDOG. It also conforms to config 39405a4a952SNicholas Piggin interfaces and parameters provided by hardlockup detector subsystem. 39505a4a952SNicholas Piggin 396c5e63197SJiri Olsaconfig HAVE_PERF_REGS 397c5e63197SJiri Olsa bool 398c5e63197SJiri Olsa help 399c5e63197SJiri Olsa Support selective register dumps for perf events. This includes 400c5e63197SJiri Olsa bit-mapping of each registers and a unique architecture id. 401c5e63197SJiri Olsa 402c5ebcedbSJiri Olsaconfig HAVE_PERF_USER_STACK_DUMP 403c5ebcedbSJiri Olsa bool 404c5ebcedbSJiri Olsa help 405c5ebcedbSJiri Olsa Support user stack dumps for perf event samples. This needs 406c5ebcedbSJiri Olsa access to the user stack pointer which is not unified across 407c5ebcedbSJiri Olsa architectures. 408c5ebcedbSJiri Olsa 409bf5438fcSJason Baronconfig HAVE_ARCH_JUMP_LABEL 410bf5438fcSJason Baron bool 411bf5438fcSJason Baron 41250ff18abSArd Biesheuvelconfig HAVE_ARCH_JUMP_LABEL_RELATIVE 41350ff18abSArd Biesheuvel bool 41450ff18abSArd Biesheuvel 4150d6e24d4SPeter Zijlstraconfig MMU_GATHER_TABLE_FREE 4160d6e24d4SPeter Zijlstra bool 4170d6e24d4SPeter Zijlstra 418ff2e6d72SPeter Zijlstraconfig MMU_GATHER_RCU_TABLE_FREE 41926723911SPeter Zijlstra bool 4200d6e24d4SPeter Zijlstra select MMU_GATHER_TABLE_FREE 42126723911SPeter Zijlstra 4223af4bd03SPeter Zijlstraconfig MMU_GATHER_PAGE_SIZE 423ed6a7935SPeter Zijlstra bool 424ed6a7935SPeter Zijlstra 42527796d03SPeter Zijlstraconfig MMU_GATHER_NO_RANGE 42627796d03SPeter Zijlstra bool 42727796d03SPeter Zijlstra 428580a586cSPeter Zijlstraconfig MMU_GATHER_NO_GATHER 429952a31c9SMartin Schwidefsky bool 4300d6e24d4SPeter Zijlstra depends on MMU_GATHER_TABLE_FREE 431952a31c9SMartin Schwidefsky 432d53c3dfbSNicholas Pigginconfig ARCH_WANT_IRQS_OFF_ACTIVATE_MM 433d53c3dfbSNicholas Piggin bool 434d53c3dfbSNicholas Piggin help 435d53c3dfbSNicholas Piggin Temporary select until all architectures can be converted to have 436d53c3dfbSNicholas Piggin irqs disabled over activate_mm. Architectures that do IPI based TLB 437d53c3dfbSNicholas Piggin shootdowns should enable this. 438d53c3dfbSNicholas Piggin 439df013ffbSHuang Yingconfig ARCH_HAVE_NMI_SAFE_CMPXCHG 440df013ffbSHuang Ying bool 441df013ffbSHuang Ying 44243570fd2SHeiko Carstensconfig HAVE_ALIGNED_STRUCT_PAGE 44343570fd2SHeiko Carstens bool 44443570fd2SHeiko Carstens help 44543570fd2SHeiko Carstens This makes sure that struct pages are double word aligned and that 44643570fd2SHeiko Carstens e.g. the SLUB allocator can perform double word atomic operations 44743570fd2SHeiko Carstens on a struct page for better performance. However selecting this 44843570fd2SHeiko Carstens might increase the size of a struct page by a word. 44943570fd2SHeiko Carstens 4504156153cSHeiko Carstensconfig HAVE_CMPXCHG_LOCAL 4514156153cSHeiko Carstens bool 4524156153cSHeiko Carstens 4532565409fSHeiko Carstensconfig HAVE_CMPXCHG_DOUBLE 4542565409fSHeiko Carstens bool 4552565409fSHeiko Carstens 45677e58496SPaul E. McKenneyconfig ARCH_WEAK_RELEASE_ACQUIRE 45777e58496SPaul E. McKenney bool 45877e58496SPaul E. McKenney 459c1d7e01dSWill Deaconconfig ARCH_WANT_IPC_PARSE_VERSION 460c1d7e01dSWill Deacon bool 461c1d7e01dSWill Deacon 462c1d7e01dSWill Deaconconfig ARCH_WANT_COMPAT_IPC_PARSE_VERSION 463c1d7e01dSWill Deacon bool 464c1d7e01dSWill Deacon 46548b25c43SChris Metcalfconfig ARCH_WANT_OLD_COMPAT_IPC 466c1d7e01dSWill Deacon select ARCH_WANT_COMPAT_IPC_PARSE_VERSION 46748b25c43SChris Metcalf bool 46848b25c43SChris Metcalf 469282a181bSYiFei Zhuconfig HAVE_ARCH_SECCOMP 470e2cfabdfSWill Drewry bool 471e2cfabdfSWill Drewry help 472282a181bSYiFei Zhu An arch should select this symbol to support seccomp mode 1 (the fixed 473282a181bSYiFei Zhu syscall policy), and must provide an overrides for __NR_seccomp_sigreturn, 474282a181bSYiFei Zhu and compat syscalls if the asm-generic/seccomp.h defaults need adjustment: 475282a181bSYiFei Zhu - __NR_seccomp_read_32 476282a181bSYiFei Zhu - __NR_seccomp_write_32 477282a181bSYiFei Zhu - __NR_seccomp_exit_32 478282a181bSYiFei Zhu - __NR_seccomp_sigreturn_32 479282a181bSYiFei Zhu 480282a181bSYiFei Zhuconfig HAVE_ARCH_SECCOMP_FILTER 481282a181bSYiFei Zhu bool 482282a181bSYiFei Zhu select HAVE_ARCH_SECCOMP 483282a181bSYiFei Zhu help 484fb0fadf9SWill Drewry An arch should select this symbol if it provides all of these things: 485282a181bSYiFei Zhu - all the requirements for HAVE_ARCH_SECCOMP 486bb6ea430SWill Drewry - syscall_get_arch() 487bb6ea430SWill Drewry - syscall_get_arguments() 488bb6ea430SWill Drewry - syscall_rollback() 489bb6ea430SWill Drewry - syscall_set_return_value() 490fb0fadf9SWill Drewry - SIGSYS siginfo_t support 491fb0fadf9SWill Drewry - secure_computing is called from a ptrace_event()-safe context 492fb0fadf9SWill Drewry - secure_computing return value is checked and a return value of -1 493fb0fadf9SWill Drewry results in the system call being skipped immediately. 49448dc92b9SKees Cook - seccomp syscall wired up 4950d8315ddSYiFei Zhu - if !HAVE_SPARSE_SYSCALL_NR, have SECCOMP_ARCH_NATIVE, 4960d8315ddSYiFei Zhu SECCOMP_ARCH_NATIVE_NR, SECCOMP_ARCH_NATIVE_NAME defined. If 4970d8315ddSYiFei Zhu COMPAT is supported, have the SECCOMP_ARCH_COMPAT* defines too. 498e2cfabdfSWill Drewry 499282a181bSYiFei Zhuconfig SECCOMP 500282a181bSYiFei Zhu prompt "Enable seccomp to safely execute untrusted bytecode" 501282a181bSYiFei Zhu def_bool y 502282a181bSYiFei Zhu depends on HAVE_ARCH_SECCOMP 503282a181bSYiFei Zhu help 504282a181bSYiFei Zhu This kernel feature is useful for number crunching applications 505282a181bSYiFei Zhu that may need to handle untrusted bytecode during their 506282a181bSYiFei Zhu execution. By using pipes or other transports made available 507282a181bSYiFei Zhu to the process as file descriptors supporting the read/write 508282a181bSYiFei Zhu syscalls, it's possible to isolate those applications in their 509282a181bSYiFei Zhu own address space using seccomp. Once seccomp is enabled via 510282a181bSYiFei Zhu prctl(PR_SET_SECCOMP) or the seccomp() syscall, it cannot be 511282a181bSYiFei Zhu disabled and the task is only allowed to execute a few safe 512282a181bSYiFei Zhu syscalls defined by each seccomp mode. 513282a181bSYiFei Zhu 514282a181bSYiFei Zhu If unsure, say Y. 515282a181bSYiFei Zhu 516e2cfabdfSWill Drewryconfig SECCOMP_FILTER 517e2cfabdfSWill Drewry def_bool y 518e2cfabdfSWill Drewry depends on HAVE_ARCH_SECCOMP_FILTER && SECCOMP && NET 519e2cfabdfSWill Drewry help 520e2cfabdfSWill Drewry Enable tasks to build secure computing environments defined 521e2cfabdfSWill Drewry in terms of Berkeley Packet Filter programs which implement 522e2cfabdfSWill Drewry task-defined system call filtering polices. 523e2cfabdfSWill Drewry 5245fb94e9cSMauro Carvalho Chehab See Documentation/userspace-api/seccomp_filter.rst for details. 525e2cfabdfSWill Drewry 5260d8315ddSYiFei Zhuconfig SECCOMP_CACHE_DEBUG 5270d8315ddSYiFei Zhu bool "Show seccomp filter cache status in /proc/pid/seccomp_cache" 5280d8315ddSYiFei Zhu depends on SECCOMP_FILTER && !HAVE_SPARSE_SYSCALL_NR 5290d8315ddSYiFei Zhu depends on PROC_FS 5300d8315ddSYiFei Zhu help 5310d8315ddSYiFei Zhu This enables the /proc/pid/seccomp_cache interface to monitor 5320d8315ddSYiFei Zhu seccomp cache data. The file format is subject to change. Reading 5330d8315ddSYiFei Zhu the file requires CAP_SYS_ADMIN. 5340d8315ddSYiFei Zhu 5350d8315ddSYiFei Zhu This option is for debugging only. Enabling presents the risk that 5360d8315ddSYiFei Zhu an adversary may be able to infer the seccomp filter logic. 5370d8315ddSYiFei Zhu 5380d8315ddSYiFei Zhu If unsure, say N. 5390d8315ddSYiFei Zhu 540afaef01cSAlexander Popovconfig HAVE_ARCH_STACKLEAK 541afaef01cSAlexander Popov bool 542afaef01cSAlexander Popov help 543afaef01cSAlexander Popov An architecture should select this if it has the code which 544afaef01cSAlexander Popov fills the used part of the kernel stack with the STACKLEAK_POISON 545afaef01cSAlexander Popov value before returning from system calls. 546afaef01cSAlexander Popov 547d148eac0SMasahiro Yamadaconfig HAVE_STACKPROTECTOR 54819952a92SKees Cook bool 54919952a92SKees Cook help 55019952a92SKees Cook An arch should select this symbol if: 55119952a92SKees Cook - it has implemented a stack canary (e.g. __stack_chk_guard) 55219952a92SKees Cook 553050e9baaSLinus Torvaldsconfig STACKPROTECTOR 5542a61f474SMasahiro Yamada bool "Stack Protector buffer overflow detection" 555d148eac0SMasahiro Yamada depends on HAVE_STACKPROTECTOR 5562a61f474SMasahiro Yamada depends on $(cc-option,-fstack-protector) 5572a61f474SMasahiro Yamada default y 5588779657dSKees Cook help 5598779657dSKees Cook This option turns on the "stack-protector" GCC feature. This 56019952a92SKees Cook feature puts, at the beginning of functions, a canary value on 56119952a92SKees Cook the stack just before the return address, and validates 56219952a92SKees Cook the value just before actually returning. Stack based buffer 56319952a92SKees Cook overflows (that need to overwrite this return address) now also 56419952a92SKees Cook overwrite the canary, which gets detected and the attack is then 56519952a92SKees Cook neutralized via a kernel panic. 56619952a92SKees Cook 5678779657dSKees Cook Functions will have the stack-protector canary logic added if they 5688779657dSKees Cook have an 8-byte or larger character array on the stack. 5698779657dSKees Cook 57019952a92SKees Cook This feature requires gcc version 4.2 or above, or a distribution 5718779657dSKees Cook gcc with the feature backported ("-fstack-protector"). 5728779657dSKees Cook 5738779657dSKees Cook On an x86 "defconfig" build, this feature adds canary checks to 5748779657dSKees Cook about 3% of all kernel functions, which increases kernel code size 5758779657dSKees Cook by about 0.3%. 5768779657dSKees Cook 577050e9baaSLinus Torvaldsconfig STACKPROTECTOR_STRONG 5782a61f474SMasahiro Yamada bool "Strong Stack Protector" 579050e9baaSLinus Torvalds depends on STACKPROTECTOR 5802a61f474SMasahiro Yamada depends on $(cc-option,-fstack-protector-strong) 5812a61f474SMasahiro Yamada default y 5828779657dSKees Cook help 5838779657dSKees Cook Functions will have the stack-protector canary logic added in any 5848779657dSKees Cook of the following conditions: 5858779657dSKees Cook 5868779657dSKees Cook - local variable's address used as part of the right hand side of an 5878779657dSKees Cook assignment or function argument 5888779657dSKees Cook - local variable is an array (or union containing an array), 5898779657dSKees Cook regardless of array type or length 5908779657dSKees Cook - uses register local variables 5918779657dSKees Cook 5928779657dSKees Cook This feature requires gcc version 4.9 or above, or a distribution 5938779657dSKees Cook gcc with the feature backported ("-fstack-protector-strong"). 5948779657dSKees Cook 5958779657dSKees Cook On an x86 "defconfig" build, this feature adds canary checks to 5968779657dSKees Cook about 20% of all kernel functions, which increases the kernel code 5978779657dSKees Cook size by about 2%. 5988779657dSKees Cook 599d08b9f0cSSami Tolvanenconfig ARCH_SUPPORTS_SHADOW_CALL_STACK 600d08b9f0cSSami Tolvanen bool 601d08b9f0cSSami Tolvanen help 602d08b9f0cSSami Tolvanen An architecture should select this if it supports Clang's Shadow 603aa7a65aeSWill Deacon Call Stack and implements runtime support for shadow stack 604aa7a65aeSWill Deacon switching. 605d08b9f0cSSami Tolvanen 606d08b9f0cSSami Tolvanenconfig SHADOW_CALL_STACK 607d08b9f0cSSami Tolvanen bool "Clang Shadow Call Stack" 608d08b9f0cSSami Tolvanen depends on CC_IS_CLANG && ARCH_SUPPORTS_SHADOW_CALL_STACK 609ddc9863eSSami Tolvanen depends on DYNAMIC_FTRACE_WITH_REGS || !FUNCTION_GRAPH_TRACER 610d08b9f0cSSami Tolvanen help 611d08b9f0cSSami Tolvanen This option enables Clang's Shadow Call Stack, which uses a 612d08b9f0cSSami Tolvanen shadow stack to protect function return addresses from being 613d08b9f0cSSami Tolvanen overwritten by an attacker. More information can be found in 614d08b9f0cSSami Tolvanen Clang's documentation: 615d08b9f0cSSami Tolvanen 616d08b9f0cSSami Tolvanen https://clang.llvm.org/docs/ShadowCallStack.html 617d08b9f0cSSami Tolvanen 618d08b9f0cSSami Tolvanen Note that security guarantees in the kernel differ from the 619d08b9f0cSSami Tolvanen ones documented for user space. The kernel must store addresses 620d08b9f0cSSami Tolvanen of shadow stacks in memory, which means an attacker capable of 621d08b9f0cSSami Tolvanen reading and writing arbitrary memory may be able to locate them 622d08b9f0cSSami Tolvanen and hijack control flow by modifying the stacks. 623d08b9f0cSSami Tolvanen 624dc5723b0SSami Tolvanenconfig LTO 625dc5723b0SSami Tolvanen bool 626dc5723b0SSami Tolvanen help 627dc5723b0SSami Tolvanen Selected if the kernel will be built using the compiler's LTO feature. 628dc5723b0SSami Tolvanen 629dc5723b0SSami Tolvanenconfig LTO_CLANG 630dc5723b0SSami Tolvanen bool 631dc5723b0SSami Tolvanen select LTO 632dc5723b0SSami Tolvanen help 633dc5723b0SSami Tolvanen Selected if the kernel will be built using Clang's LTO feature. 634dc5723b0SSami Tolvanen 635dc5723b0SSami Tolvanenconfig ARCH_SUPPORTS_LTO_CLANG 636dc5723b0SSami Tolvanen bool 637dc5723b0SSami Tolvanen help 638dc5723b0SSami Tolvanen An architecture should select this option if it supports: 639dc5723b0SSami Tolvanen - compiling with Clang, 640dc5723b0SSami Tolvanen - compiling inline assembly with Clang's integrated assembler, 641dc5723b0SSami Tolvanen - and linking with LLD. 642dc5723b0SSami Tolvanen 643dc5723b0SSami Tolvanenconfig ARCH_SUPPORTS_LTO_CLANG_THIN 644dc5723b0SSami Tolvanen bool 645dc5723b0SSami Tolvanen help 646dc5723b0SSami Tolvanen An architecture should select this option if it can support Clang's 647dc5723b0SSami Tolvanen ThinLTO mode. 648dc5723b0SSami Tolvanen 649dc5723b0SSami Tolvanenconfig HAS_LTO_CLANG 650dc5723b0SSami Tolvanen def_bool y 651dc5723b0SSami Tolvanen # Clang >= 11: https://github.com/ClangBuiltLinux/linux/issues/510 652ba64beb1SMasahiro Yamada depends on CC_IS_CLANG && CLANG_VERSION >= 110000 && LD_IS_LLD && AS_IS_LLVM 653dc5723b0SSami Tolvanen depends on $(success,$(NM) --help | head -n 1 | grep -qi llvm) 654dc5723b0SSami Tolvanen depends on $(success,$(AR) --help | head -n 1 | grep -qi llvm) 655dc5723b0SSami Tolvanen depends on ARCH_SUPPORTS_LTO_CLANG 656dc5723b0SSami Tolvanen depends on !FTRACE_MCOUNT_USE_RECORDMCOUNT 657bf3c2551SSami Tolvanen depends on !KASAN || KASAN_HW_TAGS 658dc5723b0SSami Tolvanen depends on !GCOV_KERNEL 659dc5723b0SSami Tolvanen help 660dc5723b0SSami Tolvanen The compiler and Kconfig options support building with Clang's 661dc5723b0SSami Tolvanen LTO. 662dc5723b0SSami Tolvanen 663dc5723b0SSami Tolvanenchoice 664dc5723b0SSami Tolvanen prompt "Link Time Optimization (LTO)" 665dc5723b0SSami Tolvanen default LTO_NONE 666dc5723b0SSami Tolvanen help 667dc5723b0SSami Tolvanen This option enables Link Time Optimization (LTO), which allows the 668dc5723b0SSami Tolvanen compiler to optimize binaries globally. 669dc5723b0SSami Tolvanen 670dc5723b0SSami Tolvanen If unsure, select LTO_NONE. Note that LTO is very resource-intensive 671dc5723b0SSami Tolvanen so it's disabled by default. 672dc5723b0SSami Tolvanen 673dc5723b0SSami Tolvanenconfig LTO_NONE 674dc5723b0SSami Tolvanen bool "None" 675dc5723b0SSami Tolvanen help 676dc5723b0SSami Tolvanen Build the kernel normally, without Link Time Optimization (LTO). 677dc5723b0SSami Tolvanen 678dc5723b0SSami Tolvanenconfig LTO_CLANG_FULL 679dc5723b0SSami Tolvanen bool "Clang Full LTO (EXPERIMENTAL)" 680dc5723b0SSami Tolvanen depends on HAS_LTO_CLANG 681dc5723b0SSami Tolvanen depends on !COMPILE_TEST 682dc5723b0SSami Tolvanen select LTO_CLANG 683dc5723b0SSami Tolvanen help 684dc5723b0SSami Tolvanen This option enables Clang's full Link Time Optimization (LTO), which 685dc5723b0SSami Tolvanen allows the compiler to optimize the kernel globally. If you enable 686dc5723b0SSami Tolvanen this option, the compiler generates LLVM bitcode instead of ELF 687dc5723b0SSami Tolvanen object files, and the actual compilation from bitcode happens at 688dc5723b0SSami Tolvanen the LTO link step, which may take several minutes depending on the 689dc5723b0SSami Tolvanen kernel configuration. More information can be found from LLVM's 690dc5723b0SSami Tolvanen documentation: 691dc5723b0SSami Tolvanen 692dc5723b0SSami Tolvanen https://llvm.org/docs/LinkTimeOptimization.html 693dc5723b0SSami Tolvanen 694dc5723b0SSami Tolvanen During link time, this option can use a large amount of RAM, and 695dc5723b0SSami Tolvanen may take much longer than the ThinLTO option. 696dc5723b0SSami Tolvanen 697dc5723b0SSami Tolvanenconfig LTO_CLANG_THIN 698dc5723b0SSami Tolvanen bool "Clang ThinLTO (EXPERIMENTAL)" 699dc5723b0SSami Tolvanen depends on HAS_LTO_CLANG && ARCH_SUPPORTS_LTO_CLANG_THIN 700dc5723b0SSami Tolvanen select LTO_CLANG 701dc5723b0SSami Tolvanen help 702dc5723b0SSami Tolvanen This option enables Clang's ThinLTO, which allows for parallel 703dc5723b0SSami Tolvanen optimization and faster incremental compiles compared to the 704dc5723b0SSami Tolvanen CONFIG_LTO_CLANG_FULL option. More information can be found 705dc5723b0SSami Tolvanen from Clang's documentation: 706dc5723b0SSami Tolvanen 707dc5723b0SSami Tolvanen https://clang.llvm.org/docs/ThinLTO.html 708dc5723b0SSami Tolvanen 709dc5723b0SSami Tolvanen If unsure, say Y. 710dc5723b0SSami Tolvanenendchoice 711dc5723b0SSami Tolvanen 712cf68fffbSSami Tolvanenconfig ARCH_SUPPORTS_CFI_CLANG 713cf68fffbSSami Tolvanen bool 714cf68fffbSSami Tolvanen help 715cf68fffbSSami Tolvanen An architecture should select this option if it can support Clang's 716cf68fffbSSami Tolvanen Control-Flow Integrity (CFI) checking. 717cf68fffbSSami Tolvanen 718cf68fffbSSami Tolvanenconfig CFI_CLANG 719cf68fffbSSami Tolvanen bool "Use Clang's Control Flow Integrity (CFI)" 720cf68fffbSSami Tolvanen depends on LTO_CLANG && ARCH_SUPPORTS_CFI_CLANG 721cf68fffbSSami Tolvanen # Clang >= 12: 722cf68fffbSSami Tolvanen # - https://bugs.llvm.org/show_bug.cgi?id=46258 723cf68fffbSSami Tolvanen # - https://bugs.llvm.org/show_bug.cgi?id=47479 724cf68fffbSSami Tolvanen depends on CLANG_VERSION >= 120000 725cf68fffbSSami Tolvanen select KALLSYMS 726cf68fffbSSami Tolvanen help 727cf68fffbSSami Tolvanen This option enables Clang’s forward-edge Control Flow Integrity 728cf68fffbSSami Tolvanen (CFI) checking, where the compiler injects a runtime check to each 729cf68fffbSSami Tolvanen indirect function call to ensure the target is a valid function with 730cf68fffbSSami Tolvanen the correct static type. This restricts possible call targets and 731cf68fffbSSami Tolvanen makes it more difficult for an attacker to exploit bugs that allow 732cf68fffbSSami Tolvanen the modification of stored function pointers. More information can be 733cf68fffbSSami Tolvanen found from Clang's documentation: 734cf68fffbSSami Tolvanen 735cf68fffbSSami Tolvanen https://clang.llvm.org/docs/ControlFlowIntegrity.html 736cf68fffbSSami Tolvanen 737cf68fffbSSami Tolvanenconfig CFI_CLANG_SHADOW 738cf68fffbSSami Tolvanen bool "Use CFI shadow to speed up cross-module checks" 739cf68fffbSSami Tolvanen default y 740cf68fffbSSami Tolvanen depends on CFI_CLANG && MODULES 741cf68fffbSSami Tolvanen help 742cf68fffbSSami Tolvanen If you select this option, the kernel builds a fast look-up table of 743cf68fffbSSami Tolvanen CFI check functions in loaded modules to reduce performance overhead. 744cf68fffbSSami Tolvanen 745cf68fffbSSami Tolvanen If unsure, say Y. 746cf68fffbSSami Tolvanen 747cf68fffbSSami Tolvanenconfig CFI_PERMISSIVE 748cf68fffbSSami Tolvanen bool "Use CFI in permissive mode" 749cf68fffbSSami Tolvanen depends on CFI_CLANG 750cf68fffbSSami Tolvanen help 751cf68fffbSSami Tolvanen When selected, Control Flow Integrity (CFI) violations result in a 752cf68fffbSSami Tolvanen warning instead of a kernel panic. This option should only be used 753cf68fffbSSami Tolvanen for finding indirect call type mismatches during development. 754cf68fffbSSami Tolvanen 755cf68fffbSSami Tolvanen If unsure, say N. 756cf68fffbSSami Tolvanen 7570f60a8efSKees Cookconfig HAVE_ARCH_WITHIN_STACK_FRAMES 7580f60a8efSKees Cook bool 7590f60a8efSKees Cook help 7600f60a8efSKees Cook An architecture should select this if it can walk the kernel stack 7610f60a8efSKees Cook frames to determine if an object is part of either the arguments 7620f60a8efSKees Cook or local variables (i.e. that it excludes saved return addresses, 7630f60a8efSKees Cook and similar) by implementing an inline arch_within_stack_frames(), 7640f60a8efSKees Cook which is used by CONFIG_HARDENED_USERCOPY. 7650f60a8efSKees Cook 76691d1aa43SFrederic Weisbeckerconfig HAVE_CONTEXT_TRACKING 7672b1d5024SFrederic Weisbecker bool 7682b1d5024SFrederic Weisbecker help 76991d1aa43SFrederic Weisbecker Provide kernel/user boundaries probes necessary for subsystems 77091d1aa43SFrederic Weisbecker that need it, such as userspace RCU extended quiescent state. 771490f561bSFrederic Weisbecker Syscalls need to be wrapped inside user_exit()-user_enter(), either 772490f561bSFrederic Weisbecker optimized behind static key or through the slow path using TIF_NOHZ 773490f561bSFrederic Weisbecker flag. Exceptions handlers must be wrapped as well. Irqs are already 774490f561bSFrederic Weisbecker protected inside rcu_irq_enter/rcu_irq_exit() but preemption or signal 775490f561bSFrederic Weisbecker handling on irq exit still need to be protected. 776490f561bSFrederic Weisbecker 77783c2da2eSFrederic Weisbeckerconfig HAVE_CONTEXT_TRACKING_OFFSTACK 77883c2da2eSFrederic Weisbecker bool 77983c2da2eSFrederic Weisbecker help 78083c2da2eSFrederic Weisbecker Architecture neither relies on exception_enter()/exception_exit() 78183c2da2eSFrederic Weisbecker nor on schedule_user(). Also preempt_schedule_notrace() and 78283c2da2eSFrederic Weisbecker preempt_schedule_irq() can't be called in a preemptible section 78383c2da2eSFrederic Weisbecker while context tracking is CONTEXT_USER. This feature reflects a sane 78483c2da2eSFrederic Weisbecker entry implementation where the following requirements are met on 78583c2da2eSFrederic Weisbecker critical entry code, ie: before user_exit() or after user_enter(): 78683c2da2eSFrederic Weisbecker 78783c2da2eSFrederic Weisbecker - Critical entry code isn't preemptible (or better yet: 78883c2da2eSFrederic Weisbecker not interruptible). 78983c2da2eSFrederic Weisbecker - No use of RCU read side critical sections, unless rcu_nmi_enter() 79083c2da2eSFrederic Weisbecker got called. 79183c2da2eSFrederic Weisbecker - No use of instrumentation, unless instrumentation_begin() got 79283c2da2eSFrederic Weisbecker called. 79383c2da2eSFrederic Weisbecker 794490f561bSFrederic Weisbeckerconfig HAVE_TIF_NOHZ 795490f561bSFrederic Weisbecker bool 796490f561bSFrederic Weisbecker help 797490f561bSFrederic Weisbecker Arch relies on TIF_NOHZ and syscall slow path to implement context 798490f561bSFrederic Weisbecker tracking calls to user_enter()/user_exit(). 7992b1d5024SFrederic Weisbecker 800b952741cSFrederic Weisbeckerconfig HAVE_VIRT_CPU_ACCOUNTING 801b952741cSFrederic Weisbecker bool 802b952741cSFrederic Weisbecker 8032b91ec9fSFrederic Weisbeckerconfig HAVE_VIRT_CPU_ACCOUNTING_IDLE 8042b91ec9fSFrederic Weisbecker bool 8052b91ec9fSFrederic Weisbecker help 8062b91ec9fSFrederic Weisbecker Architecture has its own way to account idle CPU time and therefore 8072b91ec9fSFrederic Weisbecker doesn't implement vtime_account_idle(). 8082b91ec9fSFrederic Weisbecker 80940565b5aSStanislaw Gruszkaconfig ARCH_HAS_SCALED_CPUTIME 81040565b5aSStanislaw Gruszka bool 81140565b5aSStanislaw Gruszka 812554b0004SKevin Hilmanconfig HAVE_VIRT_CPU_ACCOUNTING_GEN 813554b0004SKevin Hilman bool 814554b0004SKevin Hilman default y if 64BIT 815554b0004SKevin Hilman help 816554b0004SKevin Hilman With VIRT_CPU_ACCOUNTING_GEN, cputime_t becomes 64-bit. 817554b0004SKevin Hilman Before enabling this option, arch code must be audited 818554b0004SKevin Hilman to ensure there are no races in concurrent read/write of 819554b0004SKevin Hilman cputime_t. For example, reading/writing 64-bit cputime_t on 820554b0004SKevin Hilman some 32-bit arches may require multiple accesses, so proper 821554b0004SKevin Hilman locking is needed to protect against concurrent accesses. 822554b0004SKevin Hilman 823fdf9c356SFrederic Weisbeckerconfig HAVE_IRQ_TIME_ACCOUNTING 824fdf9c356SFrederic Weisbecker bool 825fdf9c356SFrederic Weisbecker help 826fdf9c356SFrederic Weisbecker Archs need to ensure they use a high enough resolution clock to 827fdf9c356SFrederic Weisbecker support irq time accounting and then call enable_sched_clock_irqtime(). 828fdf9c356SFrederic Weisbecker 829c49dd340SKalesh Singhconfig HAVE_MOVE_PUD 830c49dd340SKalesh Singh bool 831c49dd340SKalesh Singh help 832c49dd340SKalesh Singh Architectures that select this are able to move page tables at the 833c49dd340SKalesh Singh PUD level. If there are only 3 page table levels, the move effectively 834c49dd340SKalesh Singh happens at the PGD level. 835c49dd340SKalesh Singh 8362c91bd4aSJoel Fernandes (Google)config HAVE_MOVE_PMD 8372c91bd4aSJoel Fernandes (Google) bool 8382c91bd4aSJoel Fernandes (Google) help 8392c91bd4aSJoel Fernandes (Google) Archs that select this are able to move page tables at the PMD level. 8402c91bd4aSJoel Fernandes (Google) 84115626062SGerald Schaeferconfig HAVE_ARCH_TRANSPARENT_HUGEPAGE 84215626062SGerald Schaefer bool 84315626062SGerald Schaefer 844a00cc7d9SMatthew Wilcoxconfig HAVE_ARCH_TRANSPARENT_HUGEPAGE_PUD 845a00cc7d9SMatthew Wilcox bool 846a00cc7d9SMatthew Wilcox 8470ddab1d2SToshi Kaniconfig HAVE_ARCH_HUGE_VMAP 8480ddab1d2SToshi Kani bool 8490ddab1d2SToshi Kani 850121e6f32SNicholas Piggin# 851121e6f32SNicholas Piggin# Archs that select this would be capable of PMD-sized vmaps (i.e., 852121e6f32SNicholas Piggin# arch_vmap_pmd_supported() returns true), and they must make no assumptions 853121e6f32SNicholas Piggin# that vmalloc memory is mapped with PAGE_SIZE ptes. The VM_NO_HUGE_VMAP flag 854121e6f32SNicholas Piggin# can be used to prohibit arch-specific allocations from using hugepages to 855121e6f32SNicholas Piggin# help with this (e.g., modules may require it). 856121e6f32SNicholas Piggin# 857121e6f32SNicholas Pigginconfig HAVE_ARCH_HUGE_VMALLOC 858121e6f32SNicholas Piggin depends on HAVE_ARCH_HUGE_VMAP 859121e6f32SNicholas Piggin bool 860121e6f32SNicholas Piggin 8613876d4a3SAlexandre Ghiticonfig ARCH_WANT_HUGE_PMD_SHARE 8623876d4a3SAlexandre Ghiti bool 8633876d4a3SAlexandre Ghiti 8640f8975ecSPavel Emelyanovconfig HAVE_ARCH_SOFT_DIRTY 8650f8975ecSPavel Emelyanov bool 8660f8975ecSPavel Emelyanov 867786d35d4SDavid Howellsconfig HAVE_MOD_ARCH_SPECIFIC 868786d35d4SDavid Howells bool 869786d35d4SDavid Howells help 870786d35d4SDavid Howells The arch uses struct mod_arch_specific to store data. Many arches 871786d35d4SDavid Howells just need a simple module loader without arch specific data - those 872786d35d4SDavid Howells should not enable this. 873786d35d4SDavid Howells 874786d35d4SDavid Howellsconfig MODULES_USE_ELF_RELA 875786d35d4SDavid Howells bool 876786d35d4SDavid Howells help 877786d35d4SDavid Howells Modules only use ELF RELA relocations. Modules with ELF REL 878786d35d4SDavid Howells relocations will give an error. 879786d35d4SDavid Howells 880786d35d4SDavid Howellsconfig MODULES_USE_ELF_REL 881786d35d4SDavid Howells bool 882786d35d4SDavid Howells help 883786d35d4SDavid Howells Modules only use ELF REL relocations. Modules with ELF RELA 884786d35d4SDavid Howells relocations will give an error. 885786d35d4SDavid Howells 886cc1f0274SFrederic Weisbeckerconfig HAVE_IRQ_EXIT_ON_IRQ_STACK 887cc1f0274SFrederic Weisbecker bool 888cc1f0274SFrederic Weisbecker help 889cc1f0274SFrederic Weisbecker Architecture doesn't only execute the irq handler on the irq stack 890cc1f0274SFrederic Weisbecker but also irq_exit(). This way we can process softirqs on this irq 891cc1f0274SFrederic Weisbecker stack instead of switching to a new one when we call __do_softirq() 892cc1f0274SFrederic Weisbecker in the end of an hardirq. 893cc1f0274SFrederic Weisbecker This spares a stack switch and improves cache usage on softirq 894cc1f0274SFrederic Weisbecker processing. 895cc1f0274SFrederic Weisbecker 896cd1a41ceSThomas Gleixnerconfig HAVE_SOFTIRQ_ON_OWN_STACK 897cd1a41ceSThomas Gleixner bool 898cd1a41ceSThomas Gleixner help 899cd1a41ceSThomas Gleixner Architecture provides a function to run __do_softirq() on a 900c226bc3cSColin Ian King separate stack. 901cd1a41ceSThomas Gleixner 902235a8f02SKirill A. Shutemovconfig PGTABLE_LEVELS 903235a8f02SKirill A. Shutemov int 904235a8f02SKirill A. Shutemov default 2 905235a8f02SKirill A. Shutemov 9062b68f6caSKees Cookconfig ARCH_HAS_ELF_RANDOMIZE 9072b68f6caSKees Cook bool 9082b68f6caSKees Cook help 9092b68f6caSKees Cook An architecture supports choosing randomized locations for 9102b68f6caSKees Cook stack, mmap, brk, and ET_DYN. Defined functions: 9112b68f6caSKees Cook - arch_mmap_rnd() 912204db6edSKees Cook - arch_randomize_brk() 9132b68f6caSKees Cook 914d07e2259SDaniel Cashmanconfig HAVE_ARCH_MMAP_RND_BITS 915d07e2259SDaniel Cashman bool 916d07e2259SDaniel Cashman help 917d07e2259SDaniel Cashman An arch should select this symbol if it supports setting a variable 918d07e2259SDaniel Cashman number of bits for use in establishing the base address for mmap 919d07e2259SDaniel Cashman allocations, has MMU enabled and provides values for both: 920d07e2259SDaniel Cashman - ARCH_MMAP_RND_BITS_MIN 921d07e2259SDaniel Cashman - ARCH_MMAP_RND_BITS_MAX 922d07e2259SDaniel Cashman 9235f56a5dfSJiri Slabyconfig HAVE_EXIT_THREAD 9245f56a5dfSJiri Slaby bool 9255f56a5dfSJiri Slaby help 9265f56a5dfSJiri Slaby An architecture implements exit_thread. 9275f56a5dfSJiri Slaby 928d07e2259SDaniel Cashmanconfig ARCH_MMAP_RND_BITS_MIN 929d07e2259SDaniel Cashman int 930d07e2259SDaniel Cashman 931d07e2259SDaniel Cashmanconfig ARCH_MMAP_RND_BITS_MAX 932d07e2259SDaniel Cashman int 933d07e2259SDaniel Cashman 934d07e2259SDaniel Cashmanconfig ARCH_MMAP_RND_BITS_DEFAULT 935d07e2259SDaniel Cashman int 936d07e2259SDaniel Cashman 937d07e2259SDaniel Cashmanconfig ARCH_MMAP_RND_BITS 938d07e2259SDaniel Cashman int "Number of bits to use for ASLR of mmap base address" if EXPERT 939d07e2259SDaniel Cashman range ARCH_MMAP_RND_BITS_MIN ARCH_MMAP_RND_BITS_MAX 940d07e2259SDaniel Cashman default ARCH_MMAP_RND_BITS_DEFAULT if ARCH_MMAP_RND_BITS_DEFAULT 941d07e2259SDaniel Cashman default ARCH_MMAP_RND_BITS_MIN 942d07e2259SDaniel Cashman depends on HAVE_ARCH_MMAP_RND_BITS 943d07e2259SDaniel Cashman help 944d07e2259SDaniel Cashman This value can be used to select the number of bits to use to 945d07e2259SDaniel Cashman determine the random offset to the base address of vma regions 946d07e2259SDaniel Cashman resulting from mmap allocations. This value will be bounded 947d07e2259SDaniel Cashman by the architecture's minimum and maximum supported values. 948d07e2259SDaniel Cashman 949d07e2259SDaniel Cashman This value can be changed after boot using the 950d07e2259SDaniel Cashman /proc/sys/vm/mmap_rnd_bits tunable 951d07e2259SDaniel Cashman 952d07e2259SDaniel Cashmanconfig HAVE_ARCH_MMAP_RND_COMPAT_BITS 953d07e2259SDaniel Cashman bool 954d07e2259SDaniel Cashman help 955d07e2259SDaniel Cashman An arch should select this symbol if it supports running applications 956d07e2259SDaniel Cashman in compatibility mode, supports setting a variable number of bits for 957d07e2259SDaniel Cashman use in establishing the base address for mmap allocations, has MMU 958d07e2259SDaniel Cashman enabled and provides values for both: 959d07e2259SDaniel Cashman - ARCH_MMAP_RND_COMPAT_BITS_MIN 960d07e2259SDaniel Cashman - ARCH_MMAP_RND_COMPAT_BITS_MAX 961d07e2259SDaniel Cashman 962d07e2259SDaniel Cashmanconfig ARCH_MMAP_RND_COMPAT_BITS_MIN 963d07e2259SDaniel Cashman int 964d07e2259SDaniel Cashman 965d07e2259SDaniel Cashmanconfig ARCH_MMAP_RND_COMPAT_BITS_MAX 966d07e2259SDaniel Cashman int 967d07e2259SDaniel Cashman 968d07e2259SDaniel Cashmanconfig ARCH_MMAP_RND_COMPAT_BITS_DEFAULT 969d07e2259SDaniel Cashman int 970d07e2259SDaniel Cashman 971d07e2259SDaniel Cashmanconfig ARCH_MMAP_RND_COMPAT_BITS 972d07e2259SDaniel Cashman int "Number of bits to use for ASLR of mmap base address for compatible applications" if EXPERT 973d07e2259SDaniel Cashman range ARCH_MMAP_RND_COMPAT_BITS_MIN ARCH_MMAP_RND_COMPAT_BITS_MAX 974d07e2259SDaniel Cashman default ARCH_MMAP_RND_COMPAT_BITS_DEFAULT if ARCH_MMAP_RND_COMPAT_BITS_DEFAULT 975d07e2259SDaniel Cashman default ARCH_MMAP_RND_COMPAT_BITS_MIN 976d07e2259SDaniel Cashman depends on HAVE_ARCH_MMAP_RND_COMPAT_BITS 977d07e2259SDaniel Cashman help 978d07e2259SDaniel Cashman This value can be used to select the number of bits to use to 979d07e2259SDaniel Cashman determine the random offset to the base address of vma regions 980d07e2259SDaniel Cashman resulting from mmap allocations for compatible applications This 981d07e2259SDaniel Cashman value will be bounded by the architecture's minimum and maximum 982d07e2259SDaniel Cashman supported values. 983d07e2259SDaniel Cashman 984d07e2259SDaniel Cashman This value can be changed after boot using the 985d07e2259SDaniel Cashman /proc/sys/vm/mmap_rnd_compat_bits tunable 986d07e2259SDaniel Cashman 9871b028f78SDmitry Safonovconfig HAVE_ARCH_COMPAT_MMAP_BASES 9881b028f78SDmitry Safonov bool 9891b028f78SDmitry Safonov help 9901b028f78SDmitry Safonov This allows 64bit applications to invoke 32-bit mmap() syscall 9911b028f78SDmitry Safonov and vice-versa 32-bit applications to call 64-bit mmap(). 9921b028f78SDmitry Safonov Required for applications doing different bitness syscalls. 9931b028f78SDmitry Safonov 99467f3977fSAlexandre Ghiti# This allows to use a set of generic functions to determine mmap base 99567f3977fSAlexandre Ghiti# address by giving priority to top-down scheme only if the process 99667f3977fSAlexandre Ghiti# is not in legacy mode (compat task, unlimited stack size or 99767f3977fSAlexandre Ghiti# sysctl_legacy_va_layout). 99867f3977fSAlexandre Ghiti# Architecture that selects this option can provide its own version of: 99967f3977fSAlexandre Ghiti# - STACK_RND_MASK 100067f3977fSAlexandre Ghiticonfig ARCH_WANT_DEFAULT_TOPDOWN_MMAP_LAYOUT 100167f3977fSAlexandre Ghiti bool 100267f3977fSAlexandre Ghiti depends on MMU 1003e7142bf5SAlexandre Ghiti select ARCH_HAS_ELF_RANDOMIZE 100467f3977fSAlexandre Ghiti 1005b9ab5ebbSJosh Poimboeufconfig HAVE_STACK_VALIDATION 1006b9ab5ebbSJosh Poimboeuf bool 1007b9ab5ebbSJosh Poimboeuf help 1008b9ab5ebbSJosh Poimboeuf Architecture supports the 'objtool check' host tool command, which 1009b9ab5ebbSJosh Poimboeuf performs compile-time stack metadata validation. 1010b9ab5ebbSJosh Poimboeuf 1011af085d90SJosh Poimboeufconfig HAVE_RELIABLE_STACKTRACE 1012af085d90SJosh Poimboeuf bool 1013af085d90SJosh Poimboeuf help 1014140d7e88SMiroslav Benes Architecture has either save_stack_trace_tsk_reliable() or 1015140d7e88SMiroslav Benes arch_stack_walk_reliable() function which only returns a stack trace 1016140d7e88SMiroslav Benes if it can guarantee the trace is reliable. 1017af085d90SJosh Poimboeuf 1018468a9428SGeorge Spelvinconfig HAVE_ARCH_HASH 1019468a9428SGeorge Spelvin bool 1020468a9428SGeorge Spelvin default n 1021468a9428SGeorge Spelvin help 1022468a9428SGeorge Spelvin If this is set, the architecture provides an <asm/hash.h> 1023468a9428SGeorge Spelvin file which provides platform-specific implementations of some 1024468a9428SGeorge Spelvin functions in <linux/hash.h> or fs/namei.c. 1025468a9428SGeorge Spelvin 1026666047feSFinn Thainconfig HAVE_ARCH_NVRAM_OPS 1027666047feSFinn Thain bool 1028666047feSFinn Thain 10293a495511SWilliam Breathitt Grayconfig ISA_BUS_API 10303a495511SWilliam Breathitt Gray def_bool ISA 10313a495511SWilliam Breathitt Gray 1032d2125043SAl Viro# 1033d2125043SAl Viro# ABI hall of shame 1034d2125043SAl Viro# 1035d2125043SAl Viroconfig CLONE_BACKWARDS 1036d2125043SAl Viro bool 1037d2125043SAl Viro help 1038d2125043SAl Viro Architecture has tls passed as the 4th argument of clone(2), 1039d2125043SAl Viro not the 5th one. 1040d2125043SAl Viro 1041d2125043SAl Viroconfig CLONE_BACKWARDS2 1042d2125043SAl Viro bool 1043d2125043SAl Viro help 1044d2125043SAl Viro Architecture has the first two arguments of clone(2) swapped. 1045d2125043SAl Viro 1046dfa9771aSMichal Simekconfig CLONE_BACKWARDS3 1047dfa9771aSMichal Simek bool 1048dfa9771aSMichal Simek help 1049dfa9771aSMichal Simek Architecture has tls passed as the 3rd argument of clone(2), 1050dfa9771aSMichal Simek not the 5th one. 1051dfa9771aSMichal Simek 1052eaca6eaeSAl Viroconfig ODD_RT_SIGACTION 1053eaca6eaeSAl Viro bool 1054eaca6eaeSAl Viro help 1055eaca6eaeSAl Viro Architecture has unusual rt_sigaction(2) arguments 1056eaca6eaeSAl Viro 10570a0e8cdfSAl Viroconfig OLD_SIGSUSPEND 10580a0e8cdfSAl Viro bool 10590a0e8cdfSAl Viro help 10600a0e8cdfSAl Viro Architecture has old sigsuspend(2) syscall, of one-argument variety 10610a0e8cdfSAl Viro 10620a0e8cdfSAl Viroconfig OLD_SIGSUSPEND3 10630a0e8cdfSAl Viro bool 10640a0e8cdfSAl Viro help 10650a0e8cdfSAl Viro Even weirder antique ABI - three-argument sigsuspend(2) 10660a0e8cdfSAl Viro 1067495dfbf7SAl Viroconfig OLD_SIGACTION 1068495dfbf7SAl Viro bool 1069495dfbf7SAl Viro help 1070495dfbf7SAl Viro Architecture has old sigaction(2) syscall. Nope, not the same 1071495dfbf7SAl Viro as OLD_SIGSUSPEND | OLD_SIGSUSPEND3 - alpha has sigsuspend(2), 1072495dfbf7SAl Viro but fairly different variant of sigaction(2), thanks to OSF/1 1073495dfbf7SAl Viro compatibility... 1074495dfbf7SAl Viro 1075495dfbf7SAl Viroconfig COMPAT_OLD_SIGACTION 1076495dfbf7SAl Viro bool 1077495dfbf7SAl Viro 107817435e5fSDeepa Dinamaniconfig COMPAT_32BIT_TIME 1079942437c9SArnd Bergmann bool "Provide system calls for 32-bit time_t" 1080942437c9SArnd Bergmann default !64BIT || COMPAT 108117435e5fSDeepa Dinamani help 108217435e5fSDeepa Dinamani This enables 32 bit time_t support in addition to 64 bit time_t support. 108317435e5fSDeepa Dinamani This is relevant on all 32-bit architectures, and 64-bit architectures 108417435e5fSDeepa Dinamani as part of compat syscall handling. 108517435e5fSDeepa Dinamani 108687a4c375SChristoph Hellwigconfig ARCH_NO_PREEMPT 108787a4c375SChristoph Hellwig bool 108887a4c375SChristoph Hellwig 1089cb2c7d1aSMickaël Salaünconfig ARCH_EPHEMERAL_INODES 1090cb2c7d1aSMickaël Salaün def_bool n 1091cb2c7d1aSMickaël Salaün help 1092cb2c7d1aSMickaël Salaün An arch should select this symbol if it doesn't keep track of inode 1093cb2c7d1aSMickaël Salaün instances on its own, but instead relies on something else (e.g. the 1094cb2c7d1aSMickaël Salaün host kernel for an UML kernel). 1095cb2c7d1aSMickaël Salaün 1096a50a3f4bSThomas Gleixnerconfig ARCH_SUPPORTS_RT 1097a50a3f4bSThomas Gleixner bool 1098a50a3f4bSThomas Gleixner 1099fff7fb0bSZhaoxiu Zengconfig CPU_NO_EFFICIENT_FFS 1100fff7fb0bSZhaoxiu Zeng def_bool n 1101fff7fb0bSZhaoxiu Zeng 1102ba14a194SAndy Lutomirskiconfig HAVE_ARCH_VMAP_STACK 1103ba14a194SAndy Lutomirski def_bool n 1104ba14a194SAndy Lutomirski help 1105ba14a194SAndy Lutomirski An arch should select this symbol if it can support kernel stacks 1106ba14a194SAndy Lutomirski in vmalloc space. This means: 1107ba14a194SAndy Lutomirski 1108ba14a194SAndy Lutomirski - vmalloc space must be large enough to hold many kernel stacks. 1109ba14a194SAndy Lutomirski This may rule out many 32-bit architectures. 1110ba14a194SAndy Lutomirski 1111ba14a194SAndy Lutomirski - Stacks in vmalloc space need to work reliably. For example, if 1112ba14a194SAndy Lutomirski vmap page tables are created on demand, either this mechanism 1113ba14a194SAndy Lutomirski needs to work while the stack points to a virtual address with 1114ba14a194SAndy Lutomirski unpopulated page tables or arch code (switch_to() and switch_mm(), 1115ba14a194SAndy Lutomirski most likely) needs to ensure that the stack's page table entries 1116ba14a194SAndy Lutomirski are populated before running on a possibly unpopulated stack. 1117ba14a194SAndy Lutomirski 1118ba14a194SAndy Lutomirski - If the stack overflows into a guard page, something reasonable 1119ba14a194SAndy Lutomirski should happen. The definition of "reasonable" is flexible, but 1120ba14a194SAndy Lutomirski instantly rebooting without logging anything would be unfriendly. 1121ba14a194SAndy Lutomirski 1122ba14a194SAndy Lutomirskiconfig VMAP_STACK 1123ba14a194SAndy Lutomirski default y 1124ba14a194SAndy Lutomirski bool "Use a virtually-mapped stack" 1125eafb149eSDaniel Axtens depends on HAVE_ARCH_VMAP_STACK 112638dd767dSAndrey Konovalov depends on !KASAN || KASAN_HW_TAGS || KASAN_VMALLOC 1127a7f7f624SMasahiro Yamada help 1128ba14a194SAndy Lutomirski Enable this if you want the use virtually-mapped kernel stacks 1129ba14a194SAndy Lutomirski with guard pages. This causes kernel stack overflows to be 1130ba14a194SAndy Lutomirski caught immediately rather than causing difficult-to-diagnose 1131ba14a194SAndy Lutomirski corruption. 1132ba14a194SAndy Lutomirski 113338dd767dSAndrey Konovalov To use this with software KASAN modes, the architecture must support 113438dd767dSAndrey Konovalov backing virtual mappings with real shadow memory, and KASAN_VMALLOC 113538dd767dSAndrey Konovalov must be enabled. 1136ba14a194SAndy Lutomirski 113739218ff4SKees Cookconfig HAVE_ARCH_RANDOMIZE_KSTACK_OFFSET 113839218ff4SKees Cook def_bool n 113939218ff4SKees Cook help 114039218ff4SKees Cook An arch should select this symbol if it can support kernel stack 114139218ff4SKees Cook offset randomization with calls to add_random_kstack_offset() 114239218ff4SKees Cook during syscall entry and choose_random_kstack_offset() during 114339218ff4SKees Cook syscall exit. Careful removal of -fstack-protector-strong and 114439218ff4SKees Cook -fstack-protector should also be applied to the entry code and 114539218ff4SKees Cook closely examined, as the artificial stack bump looks like an array 114639218ff4SKees Cook to the compiler, so it will attempt to add canary checks regardless 114739218ff4SKees Cook of the static branch state. 114839218ff4SKees Cook 114939218ff4SKees Cookconfig RANDOMIZE_KSTACK_OFFSET_DEFAULT 115039218ff4SKees Cook bool "Randomize kernel stack offset on syscall entry" 115139218ff4SKees Cook depends on HAVE_ARCH_RANDOMIZE_KSTACK_OFFSET 115239218ff4SKees Cook help 115339218ff4SKees Cook The kernel stack offset can be randomized (after pt_regs) by 115439218ff4SKees Cook roughly 5 bits of entropy, frustrating memory corruption 115539218ff4SKees Cook attacks that depend on stack address determinism or 115639218ff4SKees Cook cross-syscall address exposures. This feature is controlled 115739218ff4SKees Cook by kernel boot param "randomize_kstack_offset=on/off", and this 115839218ff4SKees Cook config chooses the default boot state. 115939218ff4SKees Cook 1160ad21fc4fSLaura Abbottconfig ARCH_OPTIONAL_KERNEL_RWX 1161ad21fc4fSLaura Abbott def_bool n 1162ad21fc4fSLaura Abbott 1163ad21fc4fSLaura Abbottconfig ARCH_OPTIONAL_KERNEL_RWX_DEFAULT 1164ad21fc4fSLaura Abbott def_bool n 1165ad21fc4fSLaura Abbott 1166ad21fc4fSLaura Abbottconfig ARCH_HAS_STRICT_KERNEL_RWX 1167ad21fc4fSLaura Abbott def_bool n 1168ad21fc4fSLaura Abbott 11690f5bf6d0SLaura Abbottconfig STRICT_KERNEL_RWX 1170ad21fc4fSLaura Abbott bool "Make kernel text and rodata read-only" if ARCH_OPTIONAL_KERNEL_RWX 1171ad21fc4fSLaura Abbott depends on ARCH_HAS_STRICT_KERNEL_RWX 1172ad21fc4fSLaura Abbott default !ARCH_OPTIONAL_KERNEL_RWX || ARCH_OPTIONAL_KERNEL_RWX_DEFAULT 1173ad21fc4fSLaura Abbott help 1174ad21fc4fSLaura Abbott If this is set, kernel text and rodata memory will be made read-only, 1175ad21fc4fSLaura Abbott and non-text memory will be made non-executable. This provides 1176ad21fc4fSLaura Abbott protection against certain security exploits (e.g. executing the heap 1177ad21fc4fSLaura Abbott or modifying text) 1178ad21fc4fSLaura Abbott 1179ad21fc4fSLaura Abbott These features are considered standard security practice these days. 1180ad21fc4fSLaura Abbott You should say Y here in almost all cases. 1181ad21fc4fSLaura Abbott 1182ad21fc4fSLaura Abbottconfig ARCH_HAS_STRICT_MODULE_RWX 1183ad21fc4fSLaura Abbott def_bool n 1184ad21fc4fSLaura Abbott 11850f5bf6d0SLaura Abbottconfig STRICT_MODULE_RWX 1186ad21fc4fSLaura Abbott bool "Set loadable kernel module data as NX and text as RO" if ARCH_OPTIONAL_KERNEL_RWX 1187ad21fc4fSLaura Abbott depends on ARCH_HAS_STRICT_MODULE_RWX && MODULES 1188ad21fc4fSLaura Abbott default !ARCH_OPTIONAL_KERNEL_RWX || ARCH_OPTIONAL_KERNEL_RWX_DEFAULT 1189ad21fc4fSLaura Abbott help 1190ad21fc4fSLaura Abbott If this is set, module text and rodata memory will be made read-only, 1191ad21fc4fSLaura Abbott and non-text memory will be made non-executable. This provides 1192ad21fc4fSLaura Abbott protection against certain security exploits (e.g. writing to text) 1193ad21fc4fSLaura Abbott 1194ea8c64acSChristoph Hellwig# select if the architecture provides an asm/dma-direct.h header 1195ea8c64acSChristoph Hellwigconfig ARCH_HAS_PHYS_TO_DMA 1196ea8c64acSChristoph Hellwig bool 1197ea8c64acSChristoph Hellwig 119804f264d3SPaul Burtonconfig HAVE_ARCH_COMPILER_H 119904f264d3SPaul Burton bool 120004f264d3SPaul Burton help 120104f264d3SPaul Burton An architecture can select this if it provides an 120204f264d3SPaul Burton asm/compiler.h header that should be included after 120304f264d3SPaul Burton linux/compiler-*.h in order to override macro definitions that those 120404f264d3SPaul Burton headers generally provide. 120504f264d3SPaul Burton 1206271ca788SArd Biesheuvelconfig HAVE_ARCH_PREL32_RELOCATIONS 1207271ca788SArd Biesheuvel bool 1208271ca788SArd Biesheuvel help 1209271ca788SArd Biesheuvel May be selected by an architecture if it supports place-relative 1210271ca788SArd Biesheuvel 32-bit relocations, both in the toolchain and in the module loader, 1211271ca788SArd Biesheuvel in which case relative references can be used in special sections 1212271ca788SArd Biesheuvel for PCI fixup, initcalls etc which are only half the size on 64 bit 1213271ca788SArd Biesheuvel architectures, and don't require runtime relocation on relocatable 1214271ca788SArd Biesheuvel kernels. 1215271ca788SArd Biesheuvel 1216ce9084baSArd Biesheuvelconfig ARCH_USE_MEMREMAP_PROT 1217ce9084baSArd Biesheuvel bool 1218ce9084baSArd Biesheuvel 1219fb346fd9SWaiman Longconfig LOCK_EVENT_COUNTS 1220fb346fd9SWaiman Long bool "Locking event counts collection" 1221fb346fd9SWaiman Long depends on DEBUG_FS 1222a7f7f624SMasahiro Yamada help 1223fb346fd9SWaiman Long Enable light-weight counting of various locking related events 1224fb346fd9SWaiman Long in the system with minimal performance impact. This reduces 1225fb346fd9SWaiman Long the chance of application behavior change because of timing 1226fb346fd9SWaiman Long differences. The counts are reported via debugfs. 1227fb346fd9SWaiman Long 12285cf896fbSPeter Collingbourne# Select if the architecture has support for applying RELR relocations. 12295cf896fbSPeter Collingbourneconfig ARCH_HAS_RELR 12305cf896fbSPeter Collingbourne bool 12315cf896fbSPeter Collingbourne 12325cf896fbSPeter Collingbourneconfig RELR 12335cf896fbSPeter Collingbourne bool "Use RELR relocation packing" 12345cf896fbSPeter Collingbourne depends on ARCH_HAS_RELR && TOOLS_SUPPORT_RELR 12355cf896fbSPeter Collingbourne default y 12365cf896fbSPeter Collingbourne help 12375cf896fbSPeter Collingbourne Store the kernel's dynamic relocations in the RELR relocation packing 12385cf896fbSPeter Collingbourne format. Requires a compatible linker (LLD supports this feature), as 12395cf896fbSPeter Collingbourne well as compatible NM and OBJCOPY utilities (llvm-nm and llvm-objcopy 12405cf896fbSPeter Collingbourne are compatible). 12415cf896fbSPeter Collingbourne 12420c9c1d56SThiago Jung Bauermannconfig ARCH_HAS_MEM_ENCRYPT 12430c9c1d56SThiago Jung Bauermann bool 12440c9c1d56SThiago Jung Bauermann 124546b49b12STom Lendackyconfig ARCH_HAS_CC_PLATFORM 124646b49b12STom Lendacky bool 124746b49b12STom Lendacky 12480e242208SHassan Naveedconfig HAVE_SPARSE_SYSCALL_NR 12490e242208SHassan Naveed bool 12500e242208SHassan Naveed help 12510e242208SHassan Naveed An architecture should select this if its syscall numbering is sparse 12520e242208SHassan Naveed to save space. For example, MIPS architecture has a syscall array with 12530e242208SHassan Naveed entries at 4000, 5000 and 6000 locations. This option turns on syscall 12540e242208SHassan Naveed related optimizations for a given architecture. 12550e242208SHassan Naveed 1256d60d7de3SSven Schnelleconfig ARCH_HAS_VDSO_DATA 1257d60d7de3SSven Schnelle bool 1258d60d7de3SSven Schnelle 1259115284d8SJosh Poimboeufconfig HAVE_STATIC_CALL 1260115284d8SJosh Poimboeuf bool 1261115284d8SJosh Poimboeuf 12629183c3f9SJosh Poimboeufconfig HAVE_STATIC_CALL_INLINE 12639183c3f9SJosh Poimboeuf bool 12649183c3f9SJosh Poimboeuf depends on HAVE_STATIC_CALL 12659183c3f9SJosh Poimboeuf 12666ef869e0SMichal Hockoconfig HAVE_PREEMPT_DYNAMIC 12676ef869e0SMichal Hocko bool 12686ef869e0SMichal Hocko depends on HAVE_STATIC_CALL 12696ef869e0SMichal Hocko depends on GENERIC_ENTRY 12706ef869e0SMichal Hocko help 12716ef869e0SMichal Hocko Select this if the architecture support boot time preempt setting 12726ef869e0SMichal Hocko on top of static calls. It is strongly advised to support inline 12736ef869e0SMichal Hocko static call to avoid any overhead. 12746ef869e0SMichal Hocko 127559612b24SNathan Chancellorconfig ARCH_WANT_LD_ORPHAN_WARN 127659612b24SNathan Chancellor bool 127759612b24SNathan Chancellor help 127859612b24SNathan Chancellor An arch should select this symbol once all linker sections are explicitly 127959612b24SNathan Chancellor included, size-asserted, or discarded in the linker scripts. This is 128059612b24SNathan Chancellor important because we never want expected sections to be placed heuristically 128159612b24SNathan Chancellor by the linker, since the locations of such sections can change between linker 128259612b24SNathan Chancellor versions. 128359612b24SNathan Chancellor 12844f5b0c17SMike Rapoportconfig HAVE_ARCH_PFN_VALID 12854f5b0c17SMike Rapoport bool 12864f5b0c17SMike Rapoport 12875d6ad668SMike Rapoportconfig ARCH_SUPPORTS_DEBUG_PAGEALLOC 12885d6ad668SMike Rapoport bool 12895d6ad668SMike Rapoport 12902ca408d9SBrian Gerstconfig ARCH_SPLIT_ARG64 12912ca408d9SBrian Gerst bool 12922ca408d9SBrian Gerst help 12932ca408d9SBrian Gerst If a 32-bit architecture requires 64-bit arguments to be split into 12942ca408d9SBrian Gerst pairs of 32-bit arguments, select this option. 12952ca408d9SBrian Gerst 12967facdc42SAl Viroconfig ARCH_HAS_ELFCORE_COMPAT 12977facdc42SAl Viro bool 12987facdc42SAl Viro 129958e106e7SBalbir Singhconfig ARCH_HAS_PARANOID_L1D_FLUSH 130058e106e7SBalbir Singh bool 130158e106e7SBalbir Singh 13021bdda24cSThomas Gleixnerconfig DYNAMIC_SIGFRAME 13031bdda24cSThomas Gleixner bool 13041bdda24cSThomas Gleixner 1305*50468e43SJarkko Sakkinen# Select, if arch has a named attribute group bound to NUMA device nodes. 1306*50468e43SJarkko Sakkinenconfig HAVE_ARCH_NODE_DEV_GROUP 1307*50468e43SJarkko Sakkinen bool 1308*50468e43SJarkko Sakkinen 13092521f2c2SPeter Oberparleitersource "kernel/gcov/Kconfig" 131045332b1bSMasahiro Yamada 131145332b1bSMasahiro Yamadasource "scripts/gcc-plugins/Kconfig" 1312fa1b5d09SLinus Torvalds 131322471e13SRandy Dunlapendmenu 1314