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 2705736e4aSThomas Gleixnerconfig HOTPLUG_SMT 2805736e4aSThomas Gleixner bool 2905736e4aSThomas Gleixner 30125e5645SMathieu Desnoyersconfig OPROFILE 31b309a294SRobert Richter tristate "OProfile system profiling" 32125e5645SMathieu Desnoyers depends on PROFILING 33125e5645SMathieu Desnoyers depends on HAVE_OPROFILE 34d69d59f4SIngo Molnar select RING_BUFFER 359a5963ebSChristian Borntraeger select RING_BUFFER_ALLOW_SWAP 36125e5645SMathieu Desnoyers help 37125e5645SMathieu Desnoyers OProfile is a profiling system capable of profiling the 38125e5645SMathieu Desnoyers whole system, include the kernel, kernel modules, libraries, 39125e5645SMathieu Desnoyers and applications. 40125e5645SMathieu Desnoyers 41125e5645SMathieu Desnoyers If unsure, say N. 42125e5645SMathieu Desnoyers 434d4036e0SJason Yehconfig OPROFILE_EVENT_MULTIPLEX 444d4036e0SJason Yeh bool "OProfile multiplexing support (EXPERIMENTAL)" 454d4036e0SJason Yeh default n 464d4036e0SJason Yeh depends on OPROFILE && X86 474d4036e0SJason Yeh help 484d4036e0SJason Yeh The number of hardware counters is limited. The multiplexing 494d4036e0SJason Yeh feature enables OProfile to gather more events than counters 504d4036e0SJason Yeh are provided by the hardware. This is realized by switching 519332ef9dSMasahiro Yamada between events at a user specified time interval. 524d4036e0SJason Yeh 534d4036e0SJason Yeh If unsure, say N. 544d4036e0SJason Yeh 55125e5645SMathieu Desnoyersconfig HAVE_OPROFILE 569ba16087SJan Beulich bool 57125e5645SMathieu Desnoyers 58dcfce4a0SRobert Richterconfig OPROFILE_NMI_TIMER 59dcfce4a0SRobert Richter def_bool y 60af9feebeSAnton Blanchard depends on PERF_EVENTS && HAVE_PERF_EVENTS_NMI && !PPC64 61dcfce4a0SRobert Richter 62125e5645SMathieu Desnoyersconfig KPROBES 63125e5645SMathieu Desnoyers bool "Kprobes" 6405ed160eSMasami Hiramatsu depends on MODULES 65125e5645SMathieu Desnoyers depends on HAVE_KPROBES 6605ed160eSMasami Hiramatsu select KALLSYMS 67125e5645SMathieu Desnoyers help 68125e5645SMathieu Desnoyers Kprobes allows you to trap at almost any kernel address and 69125e5645SMathieu Desnoyers execute a callback function. register_kprobe() establishes 70125e5645SMathieu Desnoyers a probepoint and specifies the callback. Kprobes is useful 71125e5645SMathieu Desnoyers for kernel debugging, non-intrusive instrumentation and testing. 72125e5645SMathieu Desnoyers If in doubt, say "N". 73125e5645SMathieu Desnoyers 7445f81b1cSSteven Rostedtconfig JUMP_LABEL 75c5905afbSIngo Molnar bool "Optimize very unlikely/likely branches" 7645f81b1cSSteven Rostedt depends on HAVE_ARCH_JUMP_LABEL 77e9666d10SMasahiro Yamada depends on CC_HAS_ASM_GOTO 7845f81b1cSSteven Rostedt help 79c5905afbSIngo Molnar This option enables a transparent branch optimization that 80c5905afbSIngo Molnar makes certain almost-always-true or almost-always-false branch 81c5905afbSIngo Molnar conditions even cheaper to execute within the kernel. 8245f81b1cSSteven Rostedt 83c5905afbSIngo Molnar Certain performance-sensitive kernel code, such as trace points, 84c5905afbSIngo Molnar scheduler functionality, networking code and KVM have such 85c5905afbSIngo Molnar branches and include support for this optimization technique. 86c5905afbSIngo Molnar 87c5905afbSIngo Molnar If it is detected that the compiler has support for "asm goto", 88c5905afbSIngo Molnar the kernel will compile such branches with just a nop 89c5905afbSIngo Molnar instruction. When the condition flag is toggled to true, the 90c5905afbSIngo Molnar nop will be converted to a jump instruction to execute the 91c5905afbSIngo Molnar conditional block of instructions. 92c5905afbSIngo Molnar 93c5905afbSIngo Molnar This technique lowers overhead and stress on the branch prediction 94c5905afbSIngo Molnar of the processor and generally makes the kernel faster. The update 95c5905afbSIngo Molnar of the condition is slower, but those are always very rare. 96c5905afbSIngo Molnar 97c5905afbSIngo Molnar ( On 32-bit x86, the necessary options added to the compiler 98c5905afbSIngo Molnar flags may increase the size of the kernel slightly. ) 9945f81b1cSSteven Rostedt 1001987c947SPeter Zijlstraconfig STATIC_KEYS_SELFTEST 1011987c947SPeter Zijlstra bool "Static key selftest" 1021987c947SPeter Zijlstra depends on JUMP_LABEL 1031987c947SPeter Zijlstra help 1041987c947SPeter Zijlstra Boot time self-test of the branch patching code. 1051987c947SPeter Zijlstra 106afd66255SMasami Hiramatsuconfig OPTPROBES 1075cc718b9SMasami Hiramatsu def_bool y 1085cc718b9SMasami Hiramatsu depends on KPROBES && HAVE_OPTPROBES 10901b1d88bSThomas Gleixner select TASKS_RCU if PREEMPTION 110afd66255SMasami Hiramatsu 111e7dbfe34SMasami Hiramatsuconfig KPROBES_ON_FTRACE 112e7dbfe34SMasami Hiramatsu def_bool y 113e7dbfe34SMasami Hiramatsu depends on KPROBES && HAVE_KPROBES_ON_FTRACE 114e7dbfe34SMasami Hiramatsu depends on DYNAMIC_FTRACE_WITH_REGS 115e7dbfe34SMasami Hiramatsu help 116e7dbfe34SMasami Hiramatsu If function tracer is enabled and the arch supports full 117e7dbfe34SMasami Hiramatsu passing of pt_regs to function tracing, then kprobes can 118e7dbfe34SMasami Hiramatsu optimize on top of function tracing. 119e7dbfe34SMasami Hiramatsu 1202b144498SSrikar Dronamrajuconfig UPROBES 12109294e31SDavid A. Long def_bool n 122e8f4aa60SAllen Pais depends on ARCH_SUPPORTS_UPROBES 1232b144498SSrikar Dronamraju help 1247b2d81d4SIngo Molnar Uprobes is the user-space counterpart to kprobes: they 1257b2d81d4SIngo Molnar enable instrumentation applications (such as 'perf probe') 1267b2d81d4SIngo Molnar to establish unintrusive probes in user-space binaries and 1277b2d81d4SIngo Molnar libraries, by executing handler functions when the probes 1287b2d81d4SIngo Molnar are hit by user-space applications. 1297b2d81d4SIngo Molnar 1307b2d81d4SIngo Molnar ( These probes come in the form of single-byte breakpoints, 1317b2d81d4SIngo Molnar managed by the kernel and kept transparent to the probed 1327b2d81d4SIngo Molnar application. ) 1332b144498SSrikar Dronamraju 13458340a07SJohannes Bergconfig HAVE_EFFICIENT_UNALIGNED_ACCESS 1359ba16087SJan Beulich bool 13658340a07SJohannes Berg help 13758340a07SJohannes Berg Some architectures are unable to perform unaligned accesses 13858340a07SJohannes Berg without the use of get_unaligned/put_unaligned. Others are 13958340a07SJohannes Berg unable to perform such accesses efficiently (e.g. trap on 14058340a07SJohannes Berg unaligned access and require fixing it up in the exception 14158340a07SJohannes Berg handler.) 14258340a07SJohannes Berg 14358340a07SJohannes Berg This symbol should be selected by an architecture if it can 14458340a07SJohannes Berg perform unaligned accesses efficiently to allow different 14558340a07SJohannes Berg code paths to be selected for these cases. Some network 14658340a07SJohannes Berg drivers, for example, could opt to not fix up alignment 14758340a07SJohannes Berg problems with received packets if doing so would not help 14858340a07SJohannes Berg much. 14958340a07SJohannes Berg 15058340a07SJohannes Berg See Documentation/unaligned-memory-access.txt for more 15158340a07SJohannes Berg information on the topic of unaligned memory accesses. 15258340a07SJohannes Berg 153cf66bb93SDavid Woodhouseconfig ARCH_USE_BUILTIN_BSWAP 154cf66bb93SDavid Woodhouse bool 155cf66bb93SDavid Woodhouse help 156cf66bb93SDavid Woodhouse Modern versions of GCC (since 4.4) have builtin functions 157cf66bb93SDavid Woodhouse for handling byte-swapping. Using these, instead of the old 158cf66bb93SDavid Woodhouse inline assembler that the architecture code provides in the 159cf66bb93SDavid Woodhouse __arch_bswapXX() macros, allows the compiler to see what's 160cf66bb93SDavid Woodhouse happening and offers more opportunity for optimisation. In 161cf66bb93SDavid Woodhouse particular, the compiler will be able to combine the byteswap 162cf66bb93SDavid Woodhouse with a nearby load or store and use load-and-swap or 163cf66bb93SDavid Woodhouse store-and-swap instructions if the architecture has them. It 164cf66bb93SDavid Woodhouse should almost *never* result in code which is worse than the 165cf66bb93SDavid Woodhouse hand-coded assembler in <asm/swab.h>. But just in case it 166cf66bb93SDavid Woodhouse does, the use of the builtins is optional. 167cf66bb93SDavid Woodhouse 168cf66bb93SDavid Woodhouse Any architecture with load-and-swap or store-and-swap 169cf66bb93SDavid Woodhouse instructions should set this. And it shouldn't hurt to set it 170cf66bb93SDavid Woodhouse on architectures that don't have such instructions. 171cf66bb93SDavid Woodhouse 1729edddaa2SAnanth N Mavinakayanahalliconfig KRETPROBES 1739edddaa2SAnanth N Mavinakayanahalli def_bool y 1749edddaa2SAnanth N Mavinakayanahalli depends on KPROBES && HAVE_KRETPROBES 1759edddaa2SAnanth N Mavinakayanahalli 1767c68af6eSAvi Kivityconfig USER_RETURN_NOTIFIER 1777c68af6eSAvi Kivity bool 1787c68af6eSAvi Kivity depends on HAVE_USER_RETURN_NOTIFIER 1797c68af6eSAvi Kivity help 1807c68af6eSAvi Kivity Provide a kernel-internal notification when a cpu is about to 1817c68af6eSAvi Kivity switch to user mode. 1827c68af6eSAvi Kivity 18328b2ee20SRik van Rielconfig HAVE_IOREMAP_PROT 1849ba16087SJan Beulich bool 18528b2ee20SRik van Riel 186125e5645SMathieu Desnoyersconfig HAVE_KPROBES 1879ba16087SJan Beulich bool 1889edddaa2SAnanth N Mavinakayanahalli 1899edddaa2SAnanth N Mavinakayanahalliconfig HAVE_KRETPROBES 1909ba16087SJan Beulich bool 19174bc7ceeSArthur Kepner 192afd66255SMasami Hiramatsuconfig HAVE_OPTPROBES 193afd66255SMasami Hiramatsu bool 194d314d74cSCong Wang 195e7dbfe34SMasami Hiramatsuconfig HAVE_KPROBES_ON_FTRACE 196e7dbfe34SMasami Hiramatsu bool 197e7dbfe34SMasami Hiramatsu 198540adea3SMasami Hiramatsuconfig HAVE_FUNCTION_ERROR_INJECTION 1999802d865SJosef Bacik bool 2009802d865SJosef Bacik 20142a0bb3fSPetr Mladekconfig HAVE_NMI 20242a0bb3fSPetr Mladek bool 20342a0bb3fSPetr Mladek 2041f5a4ad9SRoland McGrath# 2051f5a4ad9SRoland McGrath# An arch should select this if it provides all these things: 2061f5a4ad9SRoland McGrath# 2071f5a4ad9SRoland McGrath# task_pt_regs() in asm/processor.h or asm/ptrace.h 2081f5a4ad9SRoland McGrath# arch_has_single_step() if there is hardware single-step support 2091f5a4ad9SRoland McGrath# arch_has_block_step() if there is hardware block-step support 2101f5a4ad9SRoland McGrath# asm/syscall.h supplying asm-generic/syscall.h interface 2111f5a4ad9SRoland McGrath# linux/regset.h user_regset interfaces 2121f5a4ad9SRoland McGrath# CORE_DUMP_USE_REGSET #define'd in linux/elf.h 2131f5a4ad9SRoland McGrath# TIF_SYSCALL_TRACE calls tracehook_report_syscall_{entry,exit} 2141f5a4ad9SRoland McGrath# TIF_NOTIFY_RESUME calls tracehook_notify_resume() 2151f5a4ad9SRoland McGrath# signal delivery calls tracehook_signal_handler() 2161f5a4ad9SRoland McGrath# 2171f5a4ad9SRoland McGrathconfig HAVE_ARCH_TRACEHOOK 2189ba16087SJan Beulich bool 2191f5a4ad9SRoland McGrath 220c64be2bbSMarek Szyprowskiconfig HAVE_DMA_CONTIGUOUS 221c64be2bbSMarek Szyprowski bool 222c64be2bbSMarek Szyprowski 22329d5e047SThomas Gleixnerconfig GENERIC_SMP_IDLE_THREAD 22429d5e047SThomas Gleixner bool 22529d5e047SThomas Gleixner 226485cf5daSKevin Hilmanconfig GENERIC_IDLE_POLL_SETUP 227485cf5daSKevin Hilman bool 228485cf5daSKevin Hilman 2296974f0c4SDaniel Micayconfig ARCH_HAS_FORTIFY_SOURCE 2306974f0c4SDaniel Micay bool 2316974f0c4SDaniel Micay help 2326974f0c4SDaniel Micay An architecture should select this when it can successfully 2336974f0c4SDaniel Micay build and run with CONFIG_FORTIFY_SOURCE. 2346974f0c4SDaniel Micay 235d8ae8a37SChristoph Hellwig# 236d8ae8a37SChristoph Hellwig# Select if the arch provides a historic keepinit alias for the retain_initrd 237d8ae8a37SChristoph Hellwig# command line option 238d8ae8a37SChristoph Hellwig# 239d8ae8a37SChristoph Hellwigconfig ARCH_HAS_KEEPINITRD 240d8ae8a37SChristoph Hellwig bool 241d8ae8a37SChristoph Hellwig 242d2852a22SDaniel Borkmann# Select if arch has all set_memory_ro/rw/x/nx() functions in asm/cacheflush.h 243d2852a22SDaniel Borkmannconfig ARCH_HAS_SET_MEMORY 244d2852a22SDaniel Borkmann bool 245d2852a22SDaniel Borkmann 246d253ca0cSRick Edgecombe# Select if arch has all set_direct_map_invalid/default() functions 247d253ca0cSRick Edgecombeconfig ARCH_HAS_SET_DIRECT_MAP 248d253ca0cSRick Edgecombe bool 249d253ca0cSRick Edgecombe 250c30700dbSChristoph Hellwig# 251fa7e2247SChristoph Hellwig# Select if the architecture provides the arch_dma_set_uncached symbol to 252fa7e2247SChristoph Hellwig# either provide an uncached segement alias for a DMA allocation, or 253fa7e2247SChristoph Hellwig# to remap the page tables in place. 254c30700dbSChristoph Hellwig# 255fa7e2247SChristoph Hellwigconfig ARCH_HAS_DMA_SET_UNCACHED 256c30700dbSChristoph Hellwig bool 257c30700dbSChristoph Hellwig 258999a5d12SChristoph Hellwig# 259999a5d12SChristoph Hellwig# Select if the architectures provides the arch_dma_clear_uncached symbol 260999a5d12SChristoph Hellwig# to undo an in-place page table remap for uncached access. 261999a5d12SChristoph Hellwig# 262999a5d12SChristoph Hellwigconfig ARCH_HAS_DMA_CLEAR_UNCACHED 263f5e10287SThomas Gleixner bool 264f5e10287SThomas Gleixner 2655905429aSKees Cook# Select if arch init_task must go in the __init_task_data section 2665905429aSKees Cookconfig ARCH_TASK_STRUCT_ON_STACK 2675905429aSKees Cook bool 2685905429aSKees Cook 2695905429aSKees Cook# Select if arch has its private alloc_task_struct() function 2705905429aSKees Cookconfig ARCH_TASK_STRUCT_ALLOCATOR 2715905429aSKees Cook bool 2725905429aSKees Cook 2735905429aSKees Cookconfig HAVE_ARCH_THREAD_STRUCT_WHITELIST 2745905429aSKees Cook bool 2755905429aSKees Cook depends on !ARCH_TASK_STRUCT_ALLOCATOR 276b235beeaSLinus Torvalds help 277b235beeaSLinus Torvalds An architecture should select this to provide hardened usercopy 278f5e10287SThomas Gleixner knowledge about what region of the thread_struct should be 279f5e10287SThomas Gleixner whitelisted for copying to userspace. Normally this is only the 2805aaeb5c0SIngo Molnar FPU registers. Specifically, arch_thread_struct_whitelist() 2815aaeb5c0SIngo Molnar should be implemented. Without this, the entire thread_struct 2825aaeb5c0SIngo Molnar field in task_struct will be left whitelisted. 2835aaeb5c0SIngo Molnar 284942fa985SYury Norov# Select if arch has its private alloc_thread_stack() function 285942fa985SYury Norovconfig ARCH_THREAD_STACK_ALLOCATOR 286942fa985SYury Norov bool 287942fa985SYury Norov 288942fa985SYury Norov# Select if arch wants to size task_struct dynamically via arch_task_struct_size: 289942fa985SYury Norovconfig ARCH_WANTS_DYNAMIC_TASK_STRUCT 290942fa985SYury Norov bool 291942fa985SYury Norov 292942fa985SYury Norovconfig ARCH_32BIT_OFF_T 293942fa985SYury Norov bool 294f850c30cSHeiko Carstens depends on !64BIT 295f850c30cSHeiko Carstens help 296e01292b1SHeiko Carstens All new 32-bit architectures should have 64-bit off_t type on 297e01292b1SHeiko Carstens userspace side which corresponds to the loff_t kernel type. This 298e01292b1SHeiko Carstens is the requirement for modern ABIs. Some existing architectures 299e01292b1SHeiko Carstens still support 32-bit off_t. This option is enabled for all such 300e01292b1SHeiko Carstens architectures explicitly. 301f850c30cSHeiko Carstens 3022ff2b7ecSMasahiro Yamadaconfig HAVE_ASM_MODVERSIONS 3032ff2b7ecSMasahiro Yamada bool 3042ff2b7ecSMasahiro Yamada help 3052ff2b7ecSMasahiro Yamada This symbol should be selected by an architecure if it provides 3062ff2b7ecSMasahiro Yamada <asm/asm-prototypes.h> to support the module versioning for symbols 3072ff2b7ecSMasahiro Yamada exported from assembly code. 3082ff2b7ecSMasahiro Yamada 3099483a578SDavid Brownellconfig HAVE_REGS_AND_STACK_ACCESS_API 3109ba16087SJan Beulich bool 3119483a578SDavid Brownell help 3129483a578SDavid Brownell This symbol should be selected by an architecure if it supports 3139483a578SDavid Brownell the API needed to access registers and stack entries from pt_regs, 3149483a578SDavid Brownell declared in asm/ptrace.h 3155ee00bd4SJoerg Roedel For example the kprobes-based event tracer needs this API. 3165ee00bd4SJoerg Roedel 317d7822b1eSMathieu Desnoyersconfig HAVE_RSEQ 318d7822b1eSMathieu Desnoyers bool 319d7822b1eSMathieu Desnoyers depends on HAVE_REGS_AND_STACK_ACCESS_API 320d7822b1eSMathieu Desnoyers help 321d7822b1eSMathieu Desnoyers This symbol should be selected by an architecture if it 322d7822b1eSMathieu Desnoyers supports an implementation of restartable sequences. 323d7822b1eSMathieu Desnoyers 3243c88ee19SMasami Hiramatsuconfig HAVE_FUNCTION_ARG_ACCESS_API 3253c88ee19SMasami Hiramatsu bool 3263c88ee19SMasami Hiramatsu help 3273c88ee19SMasami Hiramatsu This symbol should be selected by an architecure if it supports 3283c88ee19SMasami Hiramatsu the API needed to access function arguments from pt_regs, 3293c88ee19SMasami Hiramatsu declared in asm/ptrace.h 3303c88ee19SMasami Hiramatsu 331fb32e03fSMathieu Desnoyersconfig HAVE_CLK 332fb32e03fSMathieu Desnoyers bool 333fb32e03fSMathieu Desnoyers help 334fb32e03fSMathieu Desnoyers The <linux/clk.h> calls support software clock gating and 335fb32e03fSMathieu Desnoyers thus are a key power management tool on many systems. 336fb32e03fSMathieu Desnoyers 33762a038d3SK.Prasadconfig HAVE_HW_BREAKPOINT 33862a038d3SK.Prasad bool 33999e8c5a3SFrederic Weisbecker depends on PERF_EVENTS 34062a038d3SK.Prasad 3410102752eSFrederic Weisbeckerconfig HAVE_MIXED_BREAKPOINTS_REGS 3420102752eSFrederic Weisbecker bool 3430102752eSFrederic Weisbecker depends on HAVE_HW_BREAKPOINT 3440102752eSFrederic Weisbecker help 3450102752eSFrederic Weisbecker Depending on the arch implementation of hardware breakpoints, 3460102752eSFrederic Weisbecker some of them have separate registers for data and instruction 3470102752eSFrederic Weisbecker breakpoints addresses, others have mixed registers to store 3480102752eSFrederic Weisbecker them but define the access type in a control register. 3490102752eSFrederic Weisbecker Select this option if your arch implements breakpoints under the 3500102752eSFrederic Weisbecker latter fashion. 3510102752eSFrederic Weisbecker 3527c68af6eSAvi Kivityconfig HAVE_USER_RETURN_NOTIFIER 3537c68af6eSAvi Kivity bool 354a1922ed6SIngo Molnar 355c01d4323SFrederic Weisbeckerconfig HAVE_PERF_EVENTS_NMI 356c01d4323SFrederic Weisbecker bool 35723637d47SFrederic Weisbecker help 35823637d47SFrederic Weisbecker System hardware can generate an NMI using the perf event 35923637d47SFrederic Weisbecker subsystem. Also has support for calculating CPU cycle events 36023637d47SFrederic Weisbecker to determine how many clock cycles in a given period. 361c01d4323SFrederic Weisbecker 36205a4a952SNicholas Pigginconfig HAVE_HARDLOCKUP_DETECTOR_PERF 36305a4a952SNicholas Piggin bool 36405a4a952SNicholas Piggin depends on HAVE_PERF_EVENTS_NMI 36505a4a952SNicholas Piggin help 36605a4a952SNicholas Piggin The arch chooses to use the generic perf-NMI-based hardlockup 36705a4a952SNicholas Piggin detector. Must define HAVE_PERF_EVENTS_NMI. 36805a4a952SNicholas Piggin 36905a4a952SNicholas Pigginconfig HAVE_NMI_WATCHDOG 37005a4a952SNicholas Piggin depends on HAVE_NMI 37105a4a952SNicholas Piggin bool 37205a4a952SNicholas Piggin help 37305a4a952SNicholas Piggin The arch provides a low level NMI watchdog. It provides 37405a4a952SNicholas Piggin asm/nmi.h, and defines its own arch_touch_nmi_watchdog(). 37505a4a952SNicholas Piggin 37605a4a952SNicholas Pigginconfig HAVE_HARDLOCKUP_DETECTOR_ARCH 37705a4a952SNicholas Piggin bool 37805a4a952SNicholas Piggin select HAVE_NMI_WATCHDOG 37905a4a952SNicholas Piggin help 38005a4a952SNicholas Piggin The arch chooses to provide its own hardlockup detector, which is 38105a4a952SNicholas Piggin a superset of the HAVE_NMI_WATCHDOG. It also conforms to config 38205a4a952SNicholas Piggin interfaces and parameters provided by hardlockup detector subsystem. 38305a4a952SNicholas Piggin 384c5e63197SJiri Olsaconfig HAVE_PERF_REGS 385c5e63197SJiri Olsa bool 386c5e63197SJiri Olsa help 387c5e63197SJiri Olsa Support selective register dumps for perf events. This includes 388c5e63197SJiri Olsa bit-mapping of each registers and a unique architecture id. 389c5e63197SJiri Olsa 390c5ebcedbSJiri Olsaconfig HAVE_PERF_USER_STACK_DUMP 391c5ebcedbSJiri Olsa bool 392c5ebcedbSJiri Olsa help 393c5ebcedbSJiri Olsa Support user stack dumps for perf event samples. This needs 394c5ebcedbSJiri Olsa access to the user stack pointer which is not unified across 395c5ebcedbSJiri Olsa architectures. 396c5ebcedbSJiri Olsa 397bf5438fcSJason Baronconfig HAVE_ARCH_JUMP_LABEL 398bf5438fcSJason Baron bool 399bf5438fcSJason Baron 40050ff18abSArd Biesheuvelconfig HAVE_ARCH_JUMP_LABEL_RELATIVE 40150ff18abSArd Biesheuvel bool 40250ff18abSArd Biesheuvel 4030d6e24d4SPeter Zijlstraconfig MMU_GATHER_TABLE_FREE 4040d6e24d4SPeter Zijlstra bool 4050d6e24d4SPeter Zijlstra 406ff2e6d72SPeter Zijlstraconfig MMU_GATHER_RCU_TABLE_FREE 40726723911SPeter Zijlstra bool 4080d6e24d4SPeter Zijlstra select MMU_GATHER_TABLE_FREE 40926723911SPeter Zijlstra 4103af4bd03SPeter Zijlstraconfig MMU_GATHER_PAGE_SIZE 411ed6a7935SPeter Zijlstra bool 412ed6a7935SPeter Zijlstra 41327796d03SPeter Zijlstraconfig MMU_GATHER_NO_RANGE 41427796d03SPeter Zijlstra bool 41527796d03SPeter Zijlstra 416580a586cSPeter Zijlstraconfig MMU_GATHER_NO_GATHER 417952a31c9SMartin Schwidefsky bool 4180d6e24d4SPeter Zijlstra depends on MMU_GATHER_TABLE_FREE 419952a31c9SMartin Schwidefsky 420df013ffbSHuang Yingconfig ARCH_HAVE_NMI_SAFE_CMPXCHG 421df013ffbSHuang Ying bool 422df013ffbSHuang Ying 42343570fd2SHeiko Carstensconfig HAVE_ALIGNED_STRUCT_PAGE 42443570fd2SHeiko Carstens bool 42543570fd2SHeiko Carstens help 42643570fd2SHeiko Carstens This makes sure that struct pages are double word aligned and that 42743570fd2SHeiko Carstens e.g. the SLUB allocator can perform double word atomic operations 42843570fd2SHeiko Carstens on a struct page for better performance. However selecting this 42943570fd2SHeiko Carstens might increase the size of a struct page by a word. 43043570fd2SHeiko Carstens 4314156153cSHeiko Carstensconfig HAVE_CMPXCHG_LOCAL 4324156153cSHeiko Carstens bool 4334156153cSHeiko Carstens 4342565409fSHeiko Carstensconfig HAVE_CMPXCHG_DOUBLE 4352565409fSHeiko Carstens bool 4362565409fSHeiko Carstens 43777e58496SPaul E. McKenneyconfig ARCH_WEAK_RELEASE_ACQUIRE 43877e58496SPaul E. McKenney bool 43977e58496SPaul E. McKenney 440c1d7e01dSWill Deaconconfig ARCH_WANT_IPC_PARSE_VERSION 441c1d7e01dSWill Deacon bool 442c1d7e01dSWill Deacon 443c1d7e01dSWill Deaconconfig ARCH_WANT_COMPAT_IPC_PARSE_VERSION 444c1d7e01dSWill Deacon bool 445c1d7e01dSWill Deacon 44648b25c43SChris Metcalfconfig ARCH_WANT_OLD_COMPAT_IPC 447c1d7e01dSWill Deacon select ARCH_WANT_COMPAT_IPC_PARSE_VERSION 44848b25c43SChris Metcalf bool 44948b25c43SChris Metcalf 450e2cfabdfSWill Drewryconfig HAVE_ARCH_SECCOMP_FILTER 451e2cfabdfSWill Drewry bool 452e2cfabdfSWill Drewry help 453fb0fadf9SWill Drewry An arch should select this symbol if it provides all of these things: 454bb6ea430SWill Drewry - syscall_get_arch() 455bb6ea430SWill Drewry - syscall_get_arguments() 456bb6ea430SWill Drewry - syscall_rollback() 457bb6ea430SWill Drewry - syscall_set_return_value() 458fb0fadf9SWill Drewry - SIGSYS siginfo_t support 459fb0fadf9SWill Drewry - secure_computing is called from a ptrace_event()-safe context 460fb0fadf9SWill Drewry - secure_computing return value is checked and a return value of -1 461fb0fadf9SWill Drewry results in the system call being skipped immediately. 46248dc92b9SKees Cook - seccomp syscall wired up 463e2cfabdfSWill Drewry 464e2cfabdfSWill Drewryconfig SECCOMP_FILTER 465e2cfabdfSWill Drewry def_bool y 466e2cfabdfSWill Drewry depends on HAVE_ARCH_SECCOMP_FILTER && SECCOMP && NET 467e2cfabdfSWill Drewry help 468e2cfabdfSWill Drewry Enable tasks to build secure computing environments defined 469e2cfabdfSWill Drewry in terms of Berkeley Packet Filter programs which implement 470e2cfabdfSWill Drewry task-defined system call filtering polices. 471e2cfabdfSWill Drewry 4725fb94e9cSMauro Carvalho Chehab See Documentation/userspace-api/seccomp_filter.rst for details. 473e2cfabdfSWill Drewry 474afaef01cSAlexander Popovconfig HAVE_ARCH_STACKLEAK 475afaef01cSAlexander Popov bool 476afaef01cSAlexander Popov help 477afaef01cSAlexander Popov An architecture should select this if it has the code which 478afaef01cSAlexander Popov fills the used part of the kernel stack with the STACKLEAK_POISON 479afaef01cSAlexander Popov value before returning from system calls. 480afaef01cSAlexander Popov 481d148eac0SMasahiro Yamadaconfig HAVE_STACKPROTECTOR 48219952a92SKees Cook bool 48319952a92SKees Cook help 48419952a92SKees Cook An arch should select this symbol if: 48519952a92SKees Cook - it has implemented a stack canary (e.g. __stack_chk_guard) 48619952a92SKees Cook 4872a61f474SMasahiro Yamadaconfig CC_HAS_STACKPROTECTOR_NONE 4882a61f474SMasahiro Yamada def_bool $(cc-option,-fno-stack-protector) 4892a61f474SMasahiro Yamada 490050e9baaSLinus Torvaldsconfig STACKPROTECTOR 4912a61f474SMasahiro Yamada bool "Stack Protector buffer overflow detection" 492d148eac0SMasahiro Yamada depends on HAVE_STACKPROTECTOR 4932a61f474SMasahiro Yamada depends on $(cc-option,-fstack-protector) 4942a61f474SMasahiro Yamada default y 4958779657dSKees Cook help 4968779657dSKees Cook This option turns on the "stack-protector" GCC feature. This 49719952a92SKees Cook feature puts, at the beginning of functions, a canary value on 49819952a92SKees Cook the stack just before the return address, and validates 49919952a92SKees Cook the value just before actually returning. Stack based buffer 50019952a92SKees Cook overflows (that need to overwrite this return address) now also 50119952a92SKees Cook overwrite the canary, which gets detected and the attack is then 50219952a92SKees Cook neutralized via a kernel panic. 50319952a92SKees Cook 5048779657dSKees Cook Functions will have the stack-protector canary logic added if they 5058779657dSKees Cook have an 8-byte or larger character array on the stack. 5068779657dSKees Cook 50719952a92SKees Cook This feature requires gcc version 4.2 or above, or a distribution 5088779657dSKees Cook gcc with the feature backported ("-fstack-protector"). 5098779657dSKees Cook 5108779657dSKees Cook On an x86 "defconfig" build, this feature adds canary checks to 5118779657dSKees Cook about 3% of all kernel functions, which increases kernel code size 5128779657dSKees Cook by about 0.3%. 5138779657dSKees Cook 514050e9baaSLinus Torvaldsconfig STACKPROTECTOR_STRONG 5152a61f474SMasahiro Yamada bool "Strong Stack Protector" 516050e9baaSLinus Torvalds depends on STACKPROTECTOR 5172a61f474SMasahiro Yamada depends on $(cc-option,-fstack-protector-strong) 5182a61f474SMasahiro Yamada default y 5198779657dSKees Cook help 5208779657dSKees Cook Functions will have the stack-protector canary logic added in any 5218779657dSKees Cook of the following conditions: 5228779657dSKees Cook 5238779657dSKees Cook - local variable's address used as part of the right hand side of an 5248779657dSKees Cook assignment or function argument 5258779657dSKees Cook - local variable is an array (or union containing an array), 5268779657dSKees Cook regardless of array type or length 5278779657dSKees Cook - uses register local variables 5288779657dSKees Cook 5298779657dSKees Cook This feature requires gcc version 4.9 or above, or a distribution 5308779657dSKees Cook gcc with the feature backported ("-fstack-protector-strong"). 5318779657dSKees Cook 5328779657dSKees Cook On an x86 "defconfig" build, this feature adds canary checks to 5338779657dSKees Cook about 20% of all kernel functions, which increases the kernel code 5348779657dSKees Cook size by about 2%. 5358779657dSKees Cook 536d08b9f0cSSami Tolvanenconfig ARCH_SUPPORTS_SHADOW_CALL_STACK 537d08b9f0cSSami Tolvanen bool 538d08b9f0cSSami Tolvanen help 539d08b9f0cSSami Tolvanen An architecture should select this if it supports Clang's Shadow 540d08b9f0cSSami Tolvanen Call Stack, has asm/scs.h, and implements runtime support for shadow 541d08b9f0cSSami Tolvanen stack switching. 542d08b9f0cSSami Tolvanen 543d08b9f0cSSami Tolvanenconfig SHADOW_CALL_STACK 544d08b9f0cSSami Tolvanen bool "Clang Shadow Call Stack" 545d08b9f0cSSami Tolvanen depends on CC_IS_CLANG && ARCH_SUPPORTS_SHADOW_CALL_STACK 546d08b9f0cSSami Tolvanen help 547d08b9f0cSSami Tolvanen This option enables Clang's Shadow Call Stack, which uses a 548d08b9f0cSSami Tolvanen shadow stack to protect function return addresses from being 549d08b9f0cSSami Tolvanen overwritten by an attacker. More information can be found in 550d08b9f0cSSami Tolvanen Clang's documentation: 551d08b9f0cSSami Tolvanen 552d08b9f0cSSami Tolvanen https://clang.llvm.org/docs/ShadowCallStack.html 553d08b9f0cSSami Tolvanen 554d08b9f0cSSami Tolvanen Note that security guarantees in the kernel differ from the 555d08b9f0cSSami Tolvanen ones documented for user space. The kernel must store addresses 556d08b9f0cSSami Tolvanen of shadow stacks in memory, which means an attacker capable of 557d08b9f0cSSami Tolvanen reading and writing arbitrary memory may be able to locate them 558d08b9f0cSSami Tolvanen and hijack control flow by modifying the stacks. 559d08b9f0cSSami Tolvanen 5600f60a8efSKees Cookconfig HAVE_ARCH_WITHIN_STACK_FRAMES 5610f60a8efSKees Cook bool 5620f60a8efSKees Cook help 5630f60a8efSKees Cook An architecture should select this if it can walk the kernel stack 5640f60a8efSKees Cook frames to determine if an object is part of either the arguments 5650f60a8efSKees Cook or local variables (i.e. that it excludes saved return addresses, 5660f60a8efSKees Cook and similar) by implementing an inline arch_within_stack_frames(), 5670f60a8efSKees Cook which is used by CONFIG_HARDENED_USERCOPY. 5680f60a8efSKees Cook 56991d1aa43SFrederic Weisbeckerconfig HAVE_CONTEXT_TRACKING 5702b1d5024SFrederic Weisbecker bool 5712b1d5024SFrederic Weisbecker help 57291d1aa43SFrederic Weisbecker Provide kernel/user boundaries probes necessary for subsystems 57391d1aa43SFrederic Weisbecker that need it, such as userspace RCU extended quiescent state. 574490f561bSFrederic Weisbecker Syscalls need to be wrapped inside user_exit()-user_enter(), either 575490f561bSFrederic Weisbecker optimized behind static key or through the slow path using TIF_NOHZ 576490f561bSFrederic Weisbecker flag. Exceptions handlers must be wrapped as well. Irqs are already 577490f561bSFrederic Weisbecker protected inside rcu_irq_enter/rcu_irq_exit() but preemption or signal 578490f561bSFrederic Weisbecker handling on irq exit still need to be protected. 579490f561bSFrederic Weisbecker 580490f561bSFrederic Weisbeckerconfig HAVE_TIF_NOHZ 581490f561bSFrederic Weisbecker bool 582490f561bSFrederic Weisbecker help 583490f561bSFrederic Weisbecker Arch relies on TIF_NOHZ and syscall slow path to implement context 584490f561bSFrederic Weisbecker tracking calls to user_enter()/user_exit(). 5852b1d5024SFrederic Weisbecker 586b952741cSFrederic Weisbeckerconfig HAVE_VIRT_CPU_ACCOUNTING 587b952741cSFrederic Weisbecker bool 588b952741cSFrederic Weisbecker 58940565b5aSStanislaw Gruszkaconfig ARCH_HAS_SCALED_CPUTIME 59040565b5aSStanislaw Gruszka bool 59140565b5aSStanislaw Gruszka 592554b0004SKevin Hilmanconfig HAVE_VIRT_CPU_ACCOUNTING_GEN 593554b0004SKevin Hilman bool 594554b0004SKevin Hilman default y if 64BIT 595554b0004SKevin Hilman help 596554b0004SKevin Hilman With VIRT_CPU_ACCOUNTING_GEN, cputime_t becomes 64-bit. 597554b0004SKevin Hilman Before enabling this option, arch code must be audited 598554b0004SKevin Hilman to ensure there are no races in concurrent read/write of 599554b0004SKevin Hilman cputime_t. For example, reading/writing 64-bit cputime_t on 600554b0004SKevin Hilman some 32-bit arches may require multiple accesses, so proper 601554b0004SKevin Hilman locking is needed to protect against concurrent accesses. 602554b0004SKevin Hilman 603554b0004SKevin Hilman 604fdf9c356SFrederic Weisbeckerconfig HAVE_IRQ_TIME_ACCOUNTING 605fdf9c356SFrederic Weisbecker bool 606fdf9c356SFrederic Weisbecker help 607fdf9c356SFrederic Weisbecker Archs need to ensure they use a high enough resolution clock to 608fdf9c356SFrederic Weisbecker support irq time accounting and then call enable_sched_clock_irqtime(). 609fdf9c356SFrederic Weisbecker 6102c91bd4aSJoel Fernandes (Google)config HAVE_MOVE_PMD 6112c91bd4aSJoel Fernandes (Google) bool 6122c91bd4aSJoel Fernandes (Google) help 6132c91bd4aSJoel Fernandes (Google) Archs that select this are able to move page tables at the PMD level. 6142c91bd4aSJoel Fernandes (Google) 61515626062SGerald Schaeferconfig HAVE_ARCH_TRANSPARENT_HUGEPAGE 61615626062SGerald Schaefer bool 61715626062SGerald Schaefer 618a00cc7d9SMatthew Wilcoxconfig HAVE_ARCH_TRANSPARENT_HUGEPAGE_PUD 619a00cc7d9SMatthew Wilcox bool 620a00cc7d9SMatthew Wilcox 6210ddab1d2SToshi Kaniconfig HAVE_ARCH_HUGE_VMAP 6220ddab1d2SToshi Kani bool 6230ddab1d2SToshi Kani 6243876d4a3SAlexandre Ghiticonfig ARCH_WANT_HUGE_PMD_SHARE 6253876d4a3SAlexandre Ghiti bool 6263876d4a3SAlexandre Ghiti 6270f8975ecSPavel Emelyanovconfig HAVE_ARCH_SOFT_DIRTY 6280f8975ecSPavel Emelyanov bool 6290f8975ecSPavel Emelyanov 630786d35d4SDavid Howellsconfig HAVE_MOD_ARCH_SPECIFIC 631786d35d4SDavid Howells bool 632786d35d4SDavid Howells help 633786d35d4SDavid Howells The arch uses struct mod_arch_specific to store data. Many arches 634786d35d4SDavid Howells just need a simple module loader without arch specific data - those 635786d35d4SDavid Howells should not enable this. 636786d35d4SDavid Howells 637786d35d4SDavid Howellsconfig MODULES_USE_ELF_RELA 638786d35d4SDavid Howells bool 639786d35d4SDavid Howells help 640786d35d4SDavid Howells Modules only use ELF RELA relocations. Modules with ELF REL 641786d35d4SDavid Howells relocations will give an error. 642786d35d4SDavid Howells 643786d35d4SDavid Howellsconfig MODULES_USE_ELF_REL 644786d35d4SDavid Howells bool 645786d35d4SDavid Howells help 646786d35d4SDavid Howells Modules only use ELF REL relocations. Modules with ELF RELA 647786d35d4SDavid Howells relocations will give an error. 648786d35d4SDavid Howells 649cc1f0274SFrederic Weisbeckerconfig HAVE_IRQ_EXIT_ON_IRQ_STACK 650cc1f0274SFrederic Weisbecker bool 651cc1f0274SFrederic Weisbecker help 652cc1f0274SFrederic Weisbecker Architecture doesn't only execute the irq handler on the irq stack 653cc1f0274SFrederic Weisbecker but also irq_exit(). This way we can process softirqs on this irq 654cc1f0274SFrederic Weisbecker stack instead of switching to a new one when we call __do_softirq() 655cc1f0274SFrederic Weisbecker in the end of an hardirq. 656cc1f0274SFrederic Weisbecker This spares a stack switch and improves cache usage on softirq 657cc1f0274SFrederic Weisbecker processing. 658cc1f0274SFrederic Weisbecker 659235a8f02SKirill A. Shutemovconfig PGTABLE_LEVELS 660235a8f02SKirill A. Shutemov int 661235a8f02SKirill A. Shutemov default 2 662235a8f02SKirill A. Shutemov 6632b68f6caSKees Cookconfig ARCH_HAS_ELF_RANDOMIZE 6642b68f6caSKees Cook bool 6652b68f6caSKees Cook help 6662b68f6caSKees Cook An architecture supports choosing randomized locations for 6672b68f6caSKees Cook stack, mmap, brk, and ET_DYN. Defined functions: 6682b68f6caSKees Cook - arch_mmap_rnd() 669204db6edSKees Cook - arch_randomize_brk() 6702b68f6caSKees Cook 671d07e2259SDaniel Cashmanconfig HAVE_ARCH_MMAP_RND_BITS 672d07e2259SDaniel Cashman bool 673d07e2259SDaniel Cashman help 674d07e2259SDaniel Cashman An arch should select this symbol if it supports setting a variable 675d07e2259SDaniel Cashman number of bits for use in establishing the base address for mmap 676d07e2259SDaniel Cashman allocations, has MMU enabled and provides values for both: 677d07e2259SDaniel Cashman - ARCH_MMAP_RND_BITS_MIN 678d07e2259SDaniel Cashman - ARCH_MMAP_RND_BITS_MAX 679d07e2259SDaniel Cashman 6805f56a5dfSJiri Slabyconfig HAVE_EXIT_THREAD 6815f56a5dfSJiri Slaby bool 6825f56a5dfSJiri Slaby help 6835f56a5dfSJiri Slaby An architecture implements exit_thread. 6845f56a5dfSJiri Slaby 685d07e2259SDaniel Cashmanconfig ARCH_MMAP_RND_BITS_MIN 686d07e2259SDaniel Cashman int 687d07e2259SDaniel Cashman 688d07e2259SDaniel Cashmanconfig ARCH_MMAP_RND_BITS_MAX 689d07e2259SDaniel Cashman int 690d07e2259SDaniel Cashman 691d07e2259SDaniel Cashmanconfig ARCH_MMAP_RND_BITS_DEFAULT 692d07e2259SDaniel Cashman int 693d07e2259SDaniel Cashman 694d07e2259SDaniel Cashmanconfig ARCH_MMAP_RND_BITS 695d07e2259SDaniel Cashman int "Number of bits to use for ASLR of mmap base address" if EXPERT 696d07e2259SDaniel Cashman range ARCH_MMAP_RND_BITS_MIN ARCH_MMAP_RND_BITS_MAX 697d07e2259SDaniel Cashman default ARCH_MMAP_RND_BITS_DEFAULT if ARCH_MMAP_RND_BITS_DEFAULT 698d07e2259SDaniel Cashman default ARCH_MMAP_RND_BITS_MIN 699d07e2259SDaniel Cashman depends on HAVE_ARCH_MMAP_RND_BITS 700d07e2259SDaniel Cashman help 701d07e2259SDaniel Cashman This value can be used to select the number of bits to use to 702d07e2259SDaniel Cashman determine the random offset to the base address of vma regions 703d07e2259SDaniel Cashman resulting from mmap allocations. This value will be bounded 704d07e2259SDaniel Cashman by the architecture's minimum and maximum supported values. 705d07e2259SDaniel Cashman 706d07e2259SDaniel Cashman This value can be changed after boot using the 707d07e2259SDaniel Cashman /proc/sys/vm/mmap_rnd_bits tunable 708d07e2259SDaniel Cashman 709d07e2259SDaniel Cashmanconfig HAVE_ARCH_MMAP_RND_COMPAT_BITS 710d07e2259SDaniel Cashman bool 711d07e2259SDaniel Cashman help 712d07e2259SDaniel Cashman An arch should select this symbol if it supports running applications 713d07e2259SDaniel Cashman in compatibility mode, supports setting a variable number of bits for 714d07e2259SDaniel Cashman use in establishing the base address for mmap allocations, has MMU 715d07e2259SDaniel Cashman enabled and provides values for both: 716d07e2259SDaniel Cashman - ARCH_MMAP_RND_COMPAT_BITS_MIN 717d07e2259SDaniel Cashman - ARCH_MMAP_RND_COMPAT_BITS_MAX 718d07e2259SDaniel Cashman 719d07e2259SDaniel Cashmanconfig ARCH_MMAP_RND_COMPAT_BITS_MIN 720d07e2259SDaniel Cashman int 721d07e2259SDaniel Cashman 722d07e2259SDaniel Cashmanconfig ARCH_MMAP_RND_COMPAT_BITS_MAX 723d07e2259SDaniel Cashman int 724d07e2259SDaniel Cashman 725d07e2259SDaniel Cashmanconfig ARCH_MMAP_RND_COMPAT_BITS_DEFAULT 726d07e2259SDaniel Cashman int 727d07e2259SDaniel Cashman 728d07e2259SDaniel Cashmanconfig ARCH_MMAP_RND_COMPAT_BITS 729d07e2259SDaniel Cashman int "Number of bits to use for ASLR of mmap base address for compatible applications" if EXPERT 730d07e2259SDaniel Cashman range ARCH_MMAP_RND_COMPAT_BITS_MIN ARCH_MMAP_RND_COMPAT_BITS_MAX 731d07e2259SDaniel Cashman default ARCH_MMAP_RND_COMPAT_BITS_DEFAULT if ARCH_MMAP_RND_COMPAT_BITS_DEFAULT 732d07e2259SDaniel Cashman default ARCH_MMAP_RND_COMPAT_BITS_MIN 733d07e2259SDaniel Cashman depends on HAVE_ARCH_MMAP_RND_COMPAT_BITS 734d07e2259SDaniel Cashman help 735d07e2259SDaniel Cashman This value can be used to select the number of bits to use to 736d07e2259SDaniel Cashman determine the random offset to the base address of vma regions 737d07e2259SDaniel Cashman resulting from mmap allocations for compatible applications This 738d07e2259SDaniel Cashman value will be bounded by the architecture's minimum and maximum 739d07e2259SDaniel Cashman supported values. 740d07e2259SDaniel Cashman 741d07e2259SDaniel Cashman This value can be changed after boot using the 742d07e2259SDaniel Cashman /proc/sys/vm/mmap_rnd_compat_bits tunable 743d07e2259SDaniel Cashman 7441b028f78SDmitry Safonovconfig HAVE_ARCH_COMPAT_MMAP_BASES 7451b028f78SDmitry Safonov bool 7461b028f78SDmitry Safonov help 7471b028f78SDmitry Safonov This allows 64bit applications to invoke 32-bit mmap() syscall 7481b028f78SDmitry Safonov and vice-versa 32-bit applications to call 64-bit mmap(). 7491b028f78SDmitry Safonov Required for applications doing different bitness syscalls. 7501b028f78SDmitry Safonov 75167f3977fSAlexandre Ghiti# This allows to use a set of generic functions to determine mmap base 75267f3977fSAlexandre Ghiti# address by giving priority to top-down scheme only if the process 75367f3977fSAlexandre Ghiti# is not in legacy mode (compat task, unlimited stack size or 75467f3977fSAlexandre Ghiti# sysctl_legacy_va_layout). 75567f3977fSAlexandre Ghiti# Architecture that selects this option can provide its own version of: 75667f3977fSAlexandre Ghiti# - STACK_RND_MASK 75767f3977fSAlexandre Ghiticonfig ARCH_WANT_DEFAULT_TOPDOWN_MMAP_LAYOUT 75867f3977fSAlexandre Ghiti bool 75967f3977fSAlexandre Ghiti depends on MMU 760e7142bf5SAlexandre Ghiti select ARCH_HAS_ELF_RANDOMIZE 76167f3977fSAlexandre Ghiti 7623033f14aSJosh Triplettconfig HAVE_COPY_THREAD_TLS 7633033f14aSJosh Triplett bool 7643033f14aSJosh Triplett help 7653033f14aSJosh Triplett Architecture provides copy_thread_tls to accept tls argument via 7663033f14aSJosh Triplett normal C parameter passing, rather than extracting the syscall 7673033f14aSJosh Triplett argument from pt_regs. 7683033f14aSJosh Triplett 769b9ab5ebbSJosh Poimboeufconfig HAVE_STACK_VALIDATION 770b9ab5ebbSJosh Poimboeuf bool 771b9ab5ebbSJosh Poimboeuf help 772b9ab5ebbSJosh Poimboeuf Architecture supports the 'objtool check' host tool command, which 773b9ab5ebbSJosh Poimboeuf performs compile-time stack metadata validation. 774b9ab5ebbSJosh Poimboeuf 775af085d90SJosh Poimboeufconfig HAVE_RELIABLE_STACKTRACE 776af085d90SJosh Poimboeuf bool 777af085d90SJosh Poimboeuf help 778140d7e88SMiroslav Benes Architecture has either save_stack_trace_tsk_reliable() or 779140d7e88SMiroslav Benes arch_stack_walk_reliable() function which only returns a stack trace 780140d7e88SMiroslav Benes if it can guarantee the trace is reliable. 781af085d90SJosh Poimboeuf 782468a9428SGeorge Spelvinconfig HAVE_ARCH_HASH 783468a9428SGeorge Spelvin bool 784468a9428SGeorge Spelvin default n 785468a9428SGeorge Spelvin help 786468a9428SGeorge Spelvin If this is set, the architecture provides an <asm/hash.h> 787468a9428SGeorge Spelvin file which provides platform-specific implementations of some 788468a9428SGeorge Spelvin functions in <linux/hash.h> or fs/namei.c. 789468a9428SGeorge Spelvin 790666047feSFinn Thainconfig HAVE_ARCH_NVRAM_OPS 791666047feSFinn Thain bool 792666047feSFinn Thain 7933a495511SWilliam Breathitt Grayconfig ISA_BUS_API 7943a495511SWilliam Breathitt Gray def_bool ISA 7953a495511SWilliam Breathitt Gray 796d2125043SAl Viro# 797d2125043SAl Viro# ABI hall of shame 798d2125043SAl Viro# 799d2125043SAl Viroconfig CLONE_BACKWARDS 800d2125043SAl Viro bool 801d2125043SAl Viro help 802d2125043SAl Viro Architecture has tls passed as the 4th argument of clone(2), 803d2125043SAl Viro not the 5th one. 804d2125043SAl Viro 805d2125043SAl Viroconfig CLONE_BACKWARDS2 806d2125043SAl Viro bool 807d2125043SAl Viro help 808d2125043SAl Viro Architecture has the first two arguments of clone(2) swapped. 809d2125043SAl Viro 810dfa9771aSMichal Simekconfig CLONE_BACKWARDS3 811dfa9771aSMichal Simek bool 812dfa9771aSMichal Simek help 813dfa9771aSMichal Simek Architecture has tls passed as the 3rd argument of clone(2), 814dfa9771aSMichal Simek not the 5th one. 815dfa9771aSMichal Simek 816eaca6eaeSAl Viroconfig ODD_RT_SIGACTION 817eaca6eaeSAl Viro bool 818eaca6eaeSAl Viro help 819eaca6eaeSAl Viro Architecture has unusual rt_sigaction(2) arguments 820eaca6eaeSAl Viro 8210a0e8cdfSAl Viroconfig OLD_SIGSUSPEND 8220a0e8cdfSAl Viro bool 8230a0e8cdfSAl Viro help 8240a0e8cdfSAl Viro Architecture has old sigsuspend(2) syscall, of one-argument variety 8250a0e8cdfSAl Viro 8260a0e8cdfSAl Viroconfig OLD_SIGSUSPEND3 8270a0e8cdfSAl Viro bool 8280a0e8cdfSAl Viro help 8290a0e8cdfSAl Viro Even weirder antique ABI - three-argument sigsuspend(2) 8300a0e8cdfSAl Viro 831495dfbf7SAl Viroconfig OLD_SIGACTION 832495dfbf7SAl Viro bool 833495dfbf7SAl Viro help 834495dfbf7SAl Viro Architecture has old sigaction(2) syscall. Nope, not the same 835495dfbf7SAl Viro as OLD_SIGSUSPEND | OLD_SIGSUSPEND3 - alpha has sigsuspend(2), 836495dfbf7SAl Viro but fairly different variant of sigaction(2), thanks to OSF/1 837495dfbf7SAl Viro compatibility... 838495dfbf7SAl Viro 839495dfbf7SAl Viroconfig COMPAT_OLD_SIGACTION 840495dfbf7SAl Viro bool 841495dfbf7SAl Viro 84217435e5fSDeepa Dinamaniconfig COMPAT_32BIT_TIME 843942437c9SArnd Bergmann bool "Provide system calls for 32-bit time_t" 844942437c9SArnd Bergmann default !64BIT || COMPAT 84517435e5fSDeepa Dinamani help 84617435e5fSDeepa Dinamani This enables 32 bit time_t support in addition to 64 bit time_t support. 84717435e5fSDeepa Dinamani This is relevant on all 32-bit architectures, and 64-bit architectures 84817435e5fSDeepa Dinamani as part of compat syscall handling. 84917435e5fSDeepa Dinamani 85087a4c375SChristoph Hellwigconfig ARCH_NO_PREEMPT 85187a4c375SChristoph Hellwig bool 85287a4c375SChristoph Hellwig 853a50a3f4bSThomas Gleixnerconfig ARCH_SUPPORTS_RT 854a50a3f4bSThomas Gleixner bool 855a50a3f4bSThomas Gleixner 856fff7fb0bSZhaoxiu Zengconfig CPU_NO_EFFICIENT_FFS 857fff7fb0bSZhaoxiu Zeng def_bool n 858fff7fb0bSZhaoxiu Zeng 859ba14a194SAndy Lutomirskiconfig HAVE_ARCH_VMAP_STACK 860ba14a194SAndy Lutomirski def_bool n 861ba14a194SAndy Lutomirski help 862ba14a194SAndy Lutomirski An arch should select this symbol if it can support kernel stacks 863ba14a194SAndy Lutomirski in vmalloc space. This means: 864ba14a194SAndy Lutomirski 865ba14a194SAndy Lutomirski - vmalloc space must be large enough to hold many kernel stacks. 866ba14a194SAndy Lutomirski This may rule out many 32-bit architectures. 867ba14a194SAndy Lutomirski 868ba14a194SAndy Lutomirski - Stacks in vmalloc space need to work reliably. For example, if 869ba14a194SAndy Lutomirski vmap page tables are created on demand, either this mechanism 870ba14a194SAndy Lutomirski needs to work while the stack points to a virtual address with 871ba14a194SAndy Lutomirski unpopulated page tables or arch code (switch_to() and switch_mm(), 872ba14a194SAndy Lutomirski most likely) needs to ensure that the stack's page table entries 873ba14a194SAndy Lutomirski are populated before running on a possibly unpopulated stack. 874ba14a194SAndy Lutomirski 875ba14a194SAndy Lutomirski - If the stack overflows into a guard page, something reasonable 876ba14a194SAndy Lutomirski should happen. The definition of "reasonable" is flexible, but 877ba14a194SAndy Lutomirski instantly rebooting without logging anything would be unfriendly. 878ba14a194SAndy Lutomirski 879ba14a194SAndy Lutomirskiconfig VMAP_STACK 880ba14a194SAndy Lutomirski default y 881ba14a194SAndy Lutomirski bool "Use a virtually-mapped stack" 882eafb149eSDaniel Axtens depends on HAVE_ARCH_VMAP_STACK 883eafb149eSDaniel Axtens depends on !KASAN || KASAN_VMALLOC 884ba14a194SAndy Lutomirski ---help--- 885ba14a194SAndy Lutomirski Enable this if you want the use virtually-mapped kernel stacks 886ba14a194SAndy Lutomirski with guard pages. This causes kernel stack overflows to be 887ba14a194SAndy Lutomirski caught immediately rather than causing difficult-to-diagnose 888ba14a194SAndy Lutomirski corruption. 889ba14a194SAndy Lutomirski 890eafb149eSDaniel Axtens To use this with KASAN, the architecture must support backing 891eafb149eSDaniel Axtens virtual mappings with real shadow memory, and KASAN_VMALLOC must 892eafb149eSDaniel Axtens be enabled. 893ba14a194SAndy Lutomirski 894ad21fc4fSLaura Abbottconfig ARCH_OPTIONAL_KERNEL_RWX 895ad21fc4fSLaura Abbott def_bool n 896ad21fc4fSLaura Abbott 897ad21fc4fSLaura Abbottconfig ARCH_OPTIONAL_KERNEL_RWX_DEFAULT 898ad21fc4fSLaura Abbott def_bool n 899ad21fc4fSLaura Abbott 900ad21fc4fSLaura Abbottconfig ARCH_HAS_STRICT_KERNEL_RWX 901ad21fc4fSLaura Abbott def_bool n 902ad21fc4fSLaura Abbott 9030f5bf6d0SLaura Abbottconfig STRICT_KERNEL_RWX 904ad21fc4fSLaura Abbott bool "Make kernel text and rodata read-only" if ARCH_OPTIONAL_KERNEL_RWX 905ad21fc4fSLaura Abbott depends on ARCH_HAS_STRICT_KERNEL_RWX 906ad21fc4fSLaura Abbott default !ARCH_OPTIONAL_KERNEL_RWX || ARCH_OPTIONAL_KERNEL_RWX_DEFAULT 907ad21fc4fSLaura Abbott help 908ad21fc4fSLaura Abbott If this is set, kernel text and rodata memory will be made read-only, 909ad21fc4fSLaura Abbott and non-text memory will be made non-executable. This provides 910ad21fc4fSLaura Abbott protection against certain security exploits (e.g. executing the heap 911ad21fc4fSLaura Abbott or modifying text) 912ad21fc4fSLaura Abbott 913ad21fc4fSLaura Abbott These features are considered standard security practice these days. 914ad21fc4fSLaura Abbott You should say Y here in almost all cases. 915ad21fc4fSLaura Abbott 916ad21fc4fSLaura Abbottconfig ARCH_HAS_STRICT_MODULE_RWX 917ad21fc4fSLaura Abbott def_bool n 918ad21fc4fSLaura Abbott 9190f5bf6d0SLaura Abbottconfig STRICT_MODULE_RWX 920ad21fc4fSLaura Abbott bool "Set loadable kernel module data as NX and text as RO" if ARCH_OPTIONAL_KERNEL_RWX 921ad21fc4fSLaura Abbott depends on ARCH_HAS_STRICT_MODULE_RWX && MODULES 922ad21fc4fSLaura Abbott default !ARCH_OPTIONAL_KERNEL_RWX || ARCH_OPTIONAL_KERNEL_RWX_DEFAULT 923ad21fc4fSLaura Abbott help 924ad21fc4fSLaura Abbott If this is set, module text and rodata memory will be made read-only, 925ad21fc4fSLaura Abbott and non-text memory will be made non-executable. This provides 926ad21fc4fSLaura Abbott protection against certain security exploits (e.g. writing to text) 927ad21fc4fSLaura Abbott 928ea8c64acSChristoph Hellwig# select if the architecture provides an asm/dma-direct.h header 929ea8c64acSChristoph Hellwigconfig ARCH_HAS_PHYS_TO_DMA 930ea8c64acSChristoph Hellwig bool 931ea8c64acSChristoph Hellwig 93204f264d3SPaul Burtonconfig HAVE_ARCH_COMPILER_H 93304f264d3SPaul Burton bool 93404f264d3SPaul Burton help 93504f264d3SPaul Burton An architecture can select this if it provides an 93604f264d3SPaul Burton asm/compiler.h header that should be included after 93704f264d3SPaul Burton linux/compiler-*.h in order to override macro definitions that those 93804f264d3SPaul Burton headers generally provide. 93904f264d3SPaul Burton 940271ca788SArd Biesheuvelconfig HAVE_ARCH_PREL32_RELOCATIONS 941271ca788SArd Biesheuvel bool 942271ca788SArd Biesheuvel help 943271ca788SArd Biesheuvel May be selected by an architecture if it supports place-relative 944271ca788SArd Biesheuvel 32-bit relocations, both in the toolchain and in the module loader, 945271ca788SArd Biesheuvel in which case relative references can be used in special sections 946271ca788SArd Biesheuvel for PCI fixup, initcalls etc which are only half the size on 64 bit 947271ca788SArd Biesheuvel architectures, and don't require runtime relocation on relocatable 948271ca788SArd Biesheuvel kernels. 949271ca788SArd Biesheuvel 950ce9084baSArd Biesheuvelconfig ARCH_USE_MEMREMAP_PROT 951ce9084baSArd Biesheuvel bool 952ce9084baSArd Biesheuvel 953fb346fd9SWaiman Longconfig LOCK_EVENT_COUNTS 954fb346fd9SWaiman Long bool "Locking event counts collection" 955fb346fd9SWaiman Long depends on DEBUG_FS 956fb346fd9SWaiman Long ---help--- 957fb346fd9SWaiman Long Enable light-weight counting of various locking related events 958fb346fd9SWaiman Long in the system with minimal performance impact. This reduces 959fb346fd9SWaiman Long the chance of application behavior change because of timing 960fb346fd9SWaiman Long differences. The counts are reported via debugfs. 961fb346fd9SWaiman Long 9625cf896fbSPeter Collingbourne# Select if the architecture has support for applying RELR relocations. 9635cf896fbSPeter Collingbourneconfig ARCH_HAS_RELR 9645cf896fbSPeter Collingbourne bool 9655cf896fbSPeter Collingbourne 9665cf896fbSPeter Collingbourneconfig RELR 9675cf896fbSPeter Collingbourne bool "Use RELR relocation packing" 9685cf896fbSPeter Collingbourne depends on ARCH_HAS_RELR && TOOLS_SUPPORT_RELR 9695cf896fbSPeter Collingbourne default y 9705cf896fbSPeter Collingbourne help 9715cf896fbSPeter Collingbourne Store the kernel's dynamic relocations in the RELR relocation packing 9725cf896fbSPeter Collingbourne format. Requires a compatible linker (LLD supports this feature), as 9735cf896fbSPeter Collingbourne well as compatible NM and OBJCOPY utilities (llvm-nm and llvm-objcopy 9745cf896fbSPeter Collingbourne are compatible). 9755cf896fbSPeter Collingbourne 9760c9c1d56SThiago Jung Bauermannconfig ARCH_HAS_MEM_ENCRYPT 9770c9c1d56SThiago Jung Bauermann bool 9780c9c1d56SThiago Jung Bauermann 9790e242208SHassan Naveedconfig HAVE_SPARSE_SYSCALL_NR 9800e242208SHassan Naveed bool 9810e242208SHassan Naveed help 9820e242208SHassan Naveed An architecture should select this if its syscall numbering is sparse 9830e242208SHassan Naveed to save space. For example, MIPS architecture has a syscall array with 9840e242208SHassan Naveed entries at 4000, 5000 and 6000 locations. This option turns on syscall 9850e242208SHassan Naveed related optimizations for a given architecture. 9860e242208SHassan Naveed 9872521f2c2SPeter Oberparleitersource "kernel/gcov/Kconfig" 98845332b1bSMasahiro Yamada 98945332b1bSMasahiro Yamadasource "scripts/gcc-plugins/Kconfig" 990fa1b5d09SLinus Torvalds 99122471e13SRandy Dunlapendmenu 992