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 21467d2782SThiago Jung Bauermannconfig HAVE_IMA_KEXEC 22467d2782SThiago Jung Bauermann bool 23467d2782SThiago Jung Bauermann 2405736e4aSThomas Gleixnerconfig HOTPLUG_SMT 2505736e4aSThomas Gleixner bool 2605736e4aSThomas Gleixner 27125e5645SMathieu Desnoyersconfig OPROFILE 28b309a294SRobert Richter tristate "OProfile system profiling" 29125e5645SMathieu Desnoyers depends on PROFILING 30125e5645SMathieu Desnoyers depends on HAVE_OPROFILE 31d69d59f4SIngo Molnar select RING_BUFFER 329a5963ebSChristian Borntraeger select RING_BUFFER_ALLOW_SWAP 33125e5645SMathieu Desnoyers help 34125e5645SMathieu Desnoyers OProfile is a profiling system capable of profiling the 35125e5645SMathieu Desnoyers whole system, include the kernel, kernel modules, libraries, 36125e5645SMathieu Desnoyers and applications. 37125e5645SMathieu Desnoyers 38125e5645SMathieu Desnoyers If unsure, say N. 39125e5645SMathieu Desnoyers 404d4036e0SJason Yehconfig OPROFILE_EVENT_MULTIPLEX 414d4036e0SJason Yeh bool "OProfile multiplexing support (EXPERIMENTAL)" 424d4036e0SJason Yeh default n 434d4036e0SJason Yeh depends on OPROFILE && X86 444d4036e0SJason Yeh help 454d4036e0SJason Yeh The number of hardware counters is limited. The multiplexing 464d4036e0SJason Yeh feature enables OProfile to gather more events than counters 474d4036e0SJason Yeh are provided by the hardware. This is realized by switching 489332ef9dSMasahiro Yamada between events at a user specified time interval. 494d4036e0SJason Yeh 504d4036e0SJason Yeh If unsure, say N. 514d4036e0SJason Yeh 52125e5645SMathieu Desnoyersconfig HAVE_OPROFILE 539ba16087SJan Beulich bool 54125e5645SMathieu Desnoyers 55dcfce4a0SRobert Richterconfig OPROFILE_NMI_TIMER 56dcfce4a0SRobert Richter def_bool y 57af9feebeSAnton Blanchard depends on PERF_EVENTS && HAVE_PERF_EVENTS_NMI && !PPC64 58dcfce4a0SRobert Richter 59125e5645SMathieu Desnoyersconfig KPROBES 60125e5645SMathieu Desnoyers bool "Kprobes" 6105ed160eSMasami Hiramatsu depends on MODULES 62125e5645SMathieu Desnoyers depends on HAVE_KPROBES 6305ed160eSMasami Hiramatsu select KALLSYMS 64125e5645SMathieu Desnoyers help 65125e5645SMathieu Desnoyers Kprobes allows you to trap at almost any kernel address and 66125e5645SMathieu Desnoyers execute a callback function. register_kprobe() establishes 67125e5645SMathieu Desnoyers a probepoint and specifies the callback. Kprobes is useful 68125e5645SMathieu Desnoyers for kernel debugging, non-intrusive instrumentation and testing. 69125e5645SMathieu Desnoyers If in doubt, say "N". 70125e5645SMathieu Desnoyers 7145f81b1cSSteven Rostedtconfig JUMP_LABEL 72c5905afbSIngo Molnar bool "Optimize very unlikely/likely branches" 7345f81b1cSSteven Rostedt depends on HAVE_ARCH_JUMP_LABEL 7445f81b1cSSteven Rostedt help 75c5905afbSIngo Molnar This option enables a transparent branch optimization that 76c5905afbSIngo Molnar makes certain almost-always-true or almost-always-false branch 77c5905afbSIngo Molnar conditions even cheaper to execute within the kernel. 7845f81b1cSSteven Rostedt 79c5905afbSIngo Molnar Certain performance-sensitive kernel code, such as trace points, 80c5905afbSIngo Molnar scheduler functionality, networking code and KVM have such 81c5905afbSIngo Molnar branches and include support for this optimization technique. 82c5905afbSIngo Molnar 83c5905afbSIngo Molnar If it is detected that the compiler has support for "asm goto", 84c5905afbSIngo Molnar the kernel will compile such branches with just a nop 85c5905afbSIngo Molnar instruction. When the condition flag is toggled to true, the 86c5905afbSIngo Molnar nop will be converted to a jump instruction to execute the 87c5905afbSIngo Molnar conditional block of instructions. 88c5905afbSIngo Molnar 89c5905afbSIngo Molnar This technique lowers overhead and stress on the branch prediction 90c5905afbSIngo Molnar of the processor and generally makes the kernel faster. The update 91c5905afbSIngo Molnar of the condition is slower, but those are always very rare. 92c5905afbSIngo Molnar 93c5905afbSIngo Molnar ( On 32-bit x86, the necessary options added to the compiler 94c5905afbSIngo Molnar flags may increase the size of the kernel slightly. ) 9545f81b1cSSteven Rostedt 961987c947SPeter Zijlstraconfig STATIC_KEYS_SELFTEST 971987c947SPeter Zijlstra bool "Static key selftest" 981987c947SPeter Zijlstra depends on JUMP_LABEL 991987c947SPeter Zijlstra help 1001987c947SPeter Zijlstra Boot time self-test of the branch patching code. 1011987c947SPeter Zijlstra 102afd66255SMasami Hiramatsuconfig OPTPROBES 1035cc718b9SMasami Hiramatsu def_bool y 1045cc718b9SMasami Hiramatsu depends on KPROBES && HAVE_OPTPROBES 105a30b85dfSMasami Hiramatsu select TASKS_RCU if PREEMPT 106afd66255SMasami Hiramatsu 107e7dbfe34SMasami Hiramatsuconfig KPROBES_ON_FTRACE 108e7dbfe34SMasami Hiramatsu def_bool y 109e7dbfe34SMasami Hiramatsu depends on KPROBES && HAVE_KPROBES_ON_FTRACE 110e7dbfe34SMasami Hiramatsu depends on DYNAMIC_FTRACE_WITH_REGS 111e7dbfe34SMasami Hiramatsu help 112e7dbfe34SMasami Hiramatsu If function tracer is enabled and the arch supports full 113e7dbfe34SMasami Hiramatsu passing of pt_regs to function tracing, then kprobes can 114e7dbfe34SMasami Hiramatsu optimize on top of function tracing. 115e7dbfe34SMasami Hiramatsu 1162b144498SSrikar Dronamrajuconfig UPROBES 11709294e31SDavid A. Long def_bool n 118e8f4aa60SAllen Pais depends on ARCH_SUPPORTS_UPROBES 1192b144498SSrikar Dronamraju help 1207b2d81d4SIngo Molnar Uprobes is the user-space counterpart to kprobes: they 1217b2d81d4SIngo Molnar enable instrumentation applications (such as 'perf probe') 1227b2d81d4SIngo Molnar to establish unintrusive probes in user-space binaries and 1237b2d81d4SIngo Molnar libraries, by executing handler functions when the probes 1247b2d81d4SIngo Molnar are hit by user-space applications. 1257b2d81d4SIngo Molnar 1267b2d81d4SIngo Molnar ( These probes come in the form of single-byte breakpoints, 1277b2d81d4SIngo Molnar managed by the kernel and kept transparent to the probed 1287b2d81d4SIngo Molnar application. ) 1292b144498SSrikar Dronamraju 130c19fa94aSJames Hoganconfig HAVE_64BIT_ALIGNED_ACCESS 131c19fa94aSJames Hogan def_bool 64BIT && !HAVE_EFFICIENT_UNALIGNED_ACCESS 132c19fa94aSJames Hogan help 133c19fa94aSJames Hogan Some architectures require 64 bit accesses to be 64 bit 134c19fa94aSJames Hogan aligned, which also requires structs containing 64 bit values 135c19fa94aSJames Hogan to be 64 bit aligned too. This includes some 32 bit 136c19fa94aSJames Hogan architectures which can do 64 bit accesses, as well as 64 bit 137c19fa94aSJames Hogan architectures without unaligned access. 138c19fa94aSJames Hogan 139c19fa94aSJames Hogan This symbol should be selected by an architecture if 64 bit 140c19fa94aSJames Hogan accesses are required to be 64 bit aligned in this way even 141c19fa94aSJames Hogan though it is not a 64 bit architecture. 142c19fa94aSJames Hogan 143c19fa94aSJames Hogan See Documentation/unaligned-memory-access.txt for more 144c19fa94aSJames Hogan information on the topic of unaligned memory accesses. 145c19fa94aSJames Hogan 14658340a07SJohannes Bergconfig HAVE_EFFICIENT_UNALIGNED_ACCESS 1479ba16087SJan Beulich bool 14858340a07SJohannes Berg help 14958340a07SJohannes Berg Some architectures are unable to perform unaligned accesses 15058340a07SJohannes Berg without the use of get_unaligned/put_unaligned. Others are 15158340a07SJohannes Berg unable to perform such accesses efficiently (e.g. trap on 15258340a07SJohannes Berg unaligned access and require fixing it up in the exception 15358340a07SJohannes Berg handler.) 15458340a07SJohannes Berg 15558340a07SJohannes Berg This symbol should be selected by an architecture if it can 15658340a07SJohannes Berg perform unaligned accesses efficiently to allow different 15758340a07SJohannes Berg code paths to be selected for these cases. Some network 15858340a07SJohannes Berg drivers, for example, could opt to not fix up alignment 15958340a07SJohannes Berg problems with received packets if doing so would not help 16058340a07SJohannes Berg much. 16158340a07SJohannes Berg 16258340a07SJohannes Berg See Documentation/unaligned-memory-access.txt for more 16358340a07SJohannes Berg information on the topic of unaligned memory accesses. 16458340a07SJohannes Berg 165cf66bb93SDavid Woodhouseconfig ARCH_USE_BUILTIN_BSWAP 166cf66bb93SDavid Woodhouse bool 167cf66bb93SDavid Woodhouse help 168cf66bb93SDavid Woodhouse Modern versions of GCC (since 4.4) have builtin functions 169cf66bb93SDavid Woodhouse for handling byte-swapping. Using these, instead of the old 170cf66bb93SDavid Woodhouse inline assembler that the architecture code provides in the 171cf66bb93SDavid Woodhouse __arch_bswapXX() macros, allows the compiler to see what's 172cf66bb93SDavid Woodhouse happening and offers more opportunity for optimisation. In 173cf66bb93SDavid Woodhouse particular, the compiler will be able to combine the byteswap 174cf66bb93SDavid Woodhouse with a nearby load or store and use load-and-swap or 175cf66bb93SDavid Woodhouse store-and-swap instructions if the architecture has them. It 176cf66bb93SDavid Woodhouse should almost *never* result in code which is worse than the 177cf66bb93SDavid Woodhouse hand-coded assembler in <asm/swab.h>. But just in case it 178cf66bb93SDavid Woodhouse does, the use of the builtins is optional. 179cf66bb93SDavid Woodhouse 180cf66bb93SDavid Woodhouse Any architecture with load-and-swap or store-and-swap 181cf66bb93SDavid Woodhouse instructions should set this. And it shouldn't hurt to set it 182cf66bb93SDavid Woodhouse on architectures that don't have such instructions. 183cf66bb93SDavid Woodhouse 1849edddaa2SAnanth N Mavinakayanahalliconfig KRETPROBES 1859edddaa2SAnanth N Mavinakayanahalli def_bool y 1869edddaa2SAnanth N Mavinakayanahalli depends on KPROBES && HAVE_KRETPROBES 1879edddaa2SAnanth N Mavinakayanahalli 1887c68af6eSAvi Kivityconfig USER_RETURN_NOTIFIER 1897c68af6eSAvi Kivity bool 1907c68af6eSAvi Kivity depends on HAVE_USER_RETURN_NOTIFIER 1917c68af6eSAvi Kivity help 1927c68af6eSAvi Kivity Provide a kernel-internal notification when a cpu is about to 1937c68af6eSAvi Kivity switch to user mode. 1947c68af6eSAvi Kivity 19528b2ee20SRik van Rielconfig HAVE_IOREMAP_PROT 1969ba16087SJan Beulich bool 19728b2ee20SRik van Riel 198125e5645SMathieu Desnoyersconfig HAVE_KPROBES 1999ba16087SJan Beulich bool 2009edddaa2SAnanth N Mavinakayanahalli 2019edddaa2SAnanth N Mavinakayanahalliconfig HAVE_KRETPROBES 2029ba16087SJan Beulich bool 20374bc7ceeSArthur Kepner 204afd66255SMasami Hiramatsuconfig HAVE_OPTPROBES 205afd66255SMasami Hiramatsu bool 206d314d74cSCong Wang 207e7dbfe34SMasami Hiramatsuconfig HAVE_KPROBES_ON_FTRACE 208e7dbfe34SMasami Hiramatsu bool 209e7dbfe34SMasami Hiramatsu 210540adea3SMasami Hiramatsuconfig HAVE_FUNCTION_ERROR_INJECTION 2119802d865SJosef Bacik bool 2129802d865SJosef Bacik 21342a0bb3fSPetr Mladekconfig HAVE_NMI 21442a0bb3fSPetr Mladek bool 21542a0bb3fSPetr Mladek 2161f5a4ad9SRoland McGrath# 2171f5a4ad9SRoland McGrath# An arch should select this if it provides all these things: 2181f5a4ad9SRoland McGrath# 2191f5a4ad9SRoland McGrath# task_pt_regs() in asm/processor.h or asm/ptrace.h 2201f5a4ad9SRoland McGrath# arch_has_single_step() if there is hardware single-step support 2211f5a4ad9SRoland McGrath# arch_has_block_step() if there is hardware block-step support 2221f5a4ad9SRoland McGrath# asm/syscall.h supplying asm-generic/syscall.h interface 2231f5a4ad9SRoland McGrath# linux/regset.h user_regset interfaces 2241f5a4ad9SRoland McGrath# CORE_DUMP_USE_REGSET #define'd in linux/elf.h 2251f5a4ad9SRoland McGrath# TIF_SYSCALL_TRACE calls tracehook_report_syscall_{entry,exit} 2261f5a4ad9SRoland McGrath# TIF_NOTIFY_RESUME calls tracehook_notify_resume() 2271f5a4ad9SRoland McGrath# signal delivery calls tracehook_signal_handler() 2281f5a4ad9SRoland McGrath# 2291f5a4ad9SRoland McGrathconfig HAVE_ARCH_TRACEHOOK 2309ba16087SJan Beulich bool 2311f5a4ad9SRoland McGrath 232c64be2bbSMarek Szyprowskiconfig HAVE_DMA_CONTIGUOUS 233c64be2bbSMarek Szyprowski bool 234c64be2bbSMarek Szyprowski 23529d5e047SThomas Gleixnerconfig GENERIC_SMP_IDLE_THREAD 23629d5e047SThomas Gleixner bool 23729d5e047SThomas Gleixner 238485cf5daSKevin Hilmanconfig GENERIC_IDLE_POLL_SETUP 239485cf5daSKevin Hilman bool 240485cf5daSKevin Hilman 2416974f0c4SDaniel Micayconfig ARCH_HAS_FORTIFY_SOURCE 2426974f0c4SDaniel Micay bool 2436974f0c4SDaniel Micay help 2446974f0c4SDaniel Micay An architecture should select this when it can successfully 2456974f0c4SDaniel Micay build and run with CONFIG_FORTIFY_SOURCE. 2466974f0c4SDaniel Micay 247d2852a22SDaniel Borkmann# Select if arch has all set_memory_ro/rw/x/nx() functions in asm/cacheflush.h 248d2852a22SDaniel Borkmannconfig ARCH_HAS_SET_MEMORY 249d2852a22SDaniel Borkmann bool 250d2852a22SDaniel Borkmann 2510500871fSDavid Howells# Select if arch init_task must go in the __init_task_data section 2520500871fSDavid Howellsconfig ARCH_TASK_STRUCT_ON_STACK 253a4a2eb49SThomas Gleixner bool 254a4a2eb49SThomas Gleixner 255f5e10287SThomas Gleixner# Select if arch has its private alloc_task_struct() function 256f5e10287SThomas Gleixnerconfig ARCH_TASK_STRUCT_ALLOCATOR 257f5e10287SThomas Gleixner bool 258f5e10287SThomas Gleixner 2595905429aSKees Cookconfig HAVE_ARCH_THREAD_STRUCT_WHITELIST 2605905429aSKees Cook bool 2615905429aSKees Cook depends on !ARCH_TASK_STRUCT_ALLOCATOR 2625905429aSKees Cook help 2635905429aSKees Cook An architecture should select this to provide hardened usercopy 2645905429aSKees Cook knowledge about what region of the thread_struct should be 2655905429aSKees Cook whitelisted for copying to userspace. Normally this is only the 2665905429aSKees Cook FPU registers. Specifically, arch_thread_struct_whitelist() 2675905429aSKees Cook should be implemented. Without this, the entire thread_struct 2685905429aSKees Cook field in task_struct will be left whitelisted. 2695905429aSKees Cook 270b235beeaSLinus Torvalds# Select if arch has its private alloc_thread_stack() function 271b235beeaSLinus Torvaldsconfig ARCH_THREAD_STACK_ALLOCATOR 272f5e10287SThomas Gleixner bool 273f5e10287SThomas Gleixner 2745aaeb5c0SIngo Molnar# Select if arch wants to size task_struct dynamically via arch_task_struct_size: 2755aaeb5c0SIngo Molnarconfig ARCH_WANTS_DYNAMIC_TASK_STRUCT 2765aaeb5c0SIngo Molnar bool 2775aaeb5c0SIngo Molnar 278f850c30cSHeiko Carstensconfig HAVE_REGS_AND_STACK_ACCESS_API 279f850c30cSHeiko Carstens bool 280e01292b1SHeiko Carstens help 281e01292b1SHeiko Carstens This symbol should be selected by an architecure if it supports 282e01292b1SHeiko Carstens the API needed to access registers and stack entries from pt_regs, 283e01292b1SHeiko Carstens declared in asm/ptrace.h 284e01292b1SHeiko Carstens For example the kprobes-based event tracer needs this API. 285f850c30cSHeiko Carstens 286d7822b1eSMathieu Desnoyersconfig HAVE_RSEQ 287d7822b1eSMathieu Desnoyers bool 288d7822b1eSMathieu Desnoyers depends on HAVE_REGS_AND_STACK_ACCESS_API 289d7822b1eSMathieu Desnoyers help 290d7822b1eSMathieu Desnoyers This symbol should be selected by an architecture if it 291d7822b1eSMathieu Desnoyers supports an implementation of restartable sequences. 292d7822b1eSMathieu Desnoyers 2939483a578SDavid Brownellconfig HAVE_CLK 2949ba16087SJan Beulich bool 2959483a578SDavid Brownell help 2969483a578SDavid Brownell The <linux/clk.h> calls support software clock gating and 2979483a578SDavid Brownell thus are a key power management tool on many systems. 2989483a578SDavid Brownell 29962a038d3SK.Prasadconfig HAVE_HW_BREAKPOINT 30062a038d3SK.Prasad bool 30199e8c5a3SFrederic Weisbecker depends on PERF_EVENTS 30262a038d3SK.Prasad 3030102752eSFrederic Weisbeckerconfig HAVE_MIXED_BREAKPOINTS_REGS 3040102752eSFrederic Weisbecker bool 3050102752eSFrederic Weisbecker depends on HAVE_HW_BREAKPOINT 3060102752eSFrederic Weisbecker help 3070102752eSFrederic Weisbecker Depending on the arch implementation of hardware breakpoints, 3080102752eSFrederic Weisbecker some of them have separate registers for data and instruction 3090102752eSFrederic Weisbecker breakpoints addresses, others have mixed registers to store 3100102752eSFrederic Weisbecker them but define the access type in a control register. 3110102752eSFrederic Weisbecker Select this option if your arch implements breakpoints under the 3120102752eSFrederic Weisbecker latter fashion. 3130102752eSFrederic Weisbecker 3147c68af6eSAvi Kivityconfig HAVE_USER_RETURN_NOTIFIER 3157c68af6eSAvi Kivity bool 316a1922ed6SIngo Molnar 317c01d4323SFrederic Weisbeckerconfig HAVE_PERF_EVENTS_NMI 318c01d4323SFrederic Weisbecker bool 31923637d47SFrederic Weisbecker help 32023637d47SFrederic Weisbecker System hardware can generate an NMI using the perf event 32123637d47SFrederic Weisbecker subsystem. Also has support for calculating CPU cycle events 32223637d47SFrederic Weisbecker to determine how many clock cycles in a given period. 323c01d4323SFrederic Weisbecker 32405a4a952SNicholas Pigginconfig HAVE_HARDLOCKUP_DETECTOR_PERF 32505a4a952SNicholas Piggin bool 32605a4a952SNicholas Piggin depends on HAVE_PERF_EVENTS_NMI 32705a4a952SNicholas Piggin help 32805a4a952SNicholas Piggin The arch chooses to use the generic perf-NMI-based hardlockup 32905a4a952SNicholas Piggin detector. Must define HAVE_PERF_EVENTS_NMI. 33005a4a952SNicholas Piggin 33105a4a952SNicholas Pigginconfig HAVE_NMI_WATCHDOG 33205a4a952SNicholas Piggin depends on HAVE_NMI 33305a4a952SNicholas Piggin bool 33405a4a952SNicholas Piggin help 33505a4a952SNicholas Piggin The arch provides a low level NMI watchdog. It provides 33605a4a952SNicholas Piggin asm/nmi.h, and defines its own arch_touch_nmi_watchdog(). 33705a4a952SNicholas Piggin 33805a4a952SNicholas Pigginconfig HAVE_HARDLOCKUP_DETECTOR_ARCH 33905a4a952SNicholas Piggin bool 34005a4a952SNicholas Piggin select HAVE_NMI_WATCHDOG 34105a4a952SNicholas Piggin help 34205a4a952SNicholas Piggin The arch chooses to provide its own hardlockup detector, which is 34305a4a952SNicholas Piggin a superset of the HAVE_NMI_WATCHDOG. It also conforms to config 34405a4a952SNicholas Piggin interfaces and parameters provided by hardlockup detector subsystem. 34505a4a952SNicholas Piggin 346c5e63197SJiri Olsaconfig HAVE_PERF_REGS 347c5e63197SJiri Olsa bool 348c5e63197SJiri Olsa help 349c5e63197SJiri Olsa Support selective register dumps for perf events. This includes 350c5e63197SJiri Olsa bit-mapping of each registers and a unique architecture id. 351c5e63197SJiri Olsa 352c5ebcedbSJiri Olsaconfig HAVE_PERF_USER_STACK_DUMP 353c5ebcedbSJiri Olsa bool 354c5ebcedbSJiri Olsa help 355c5ebcedbSJiri Olsa Support user stack dumps for perf event samples. This needs 356c5ebcedbSJiri Olsa access to the user stack pointer which is not unified across 357c5ebcedbSJiri Olsa architectures. 358c5ebcedbSJiri Olsa 359bf5438fcSJason Baronconfig HAVE_ARCH_JUMP_LABEL 360bf5438fcSJason Baron bool 361bf5438fcSJason Baron 36226723911SPeter Zijlstraconfig HAVE_RCU_TABLE_FREE 36326723911SPeter Zijlstra bool 36426723911SPeter Zijlstra 365df013ffbSHuang Yingconfig ARCH_HAVE_NMI_SAFE_CMPXCHG 366df013ffbSHuang Ying bool 367df013ffbSHuang Ying 36843570fd2SHeiko Carstensconfig HAVE_ALIGNED_STRUCT_PAGE 36943570fd2SHeiko Carstens bool 37043570fd2SHeiko Carstens help 37143570fd2SHeiko Carstens This makes sure that struct pages are double word aligned and that 37243570fd2SHeiko Carstens e.g. the SLUB allocator can perform double word atomic operations 37343570fd2SHeiko Carstens on a struct page for better performance. However selecting this 37443570fd2SHeiko Carstens might increase the size of a struct page by a word. 37543570fd2SHeiko Carstens 3764156153cSHeiko Carstensconfig HAVE_CMPXCHG_LOCAL 3774156153cSHeiko Carstens bool 3784156153cSHeiko Carstens 3792565409fSHeiko Carstensconfig HAVE_CMPXCHG_DOUBLE 3802565409fSHeiko Carstens bool 3812565409fSHeiko Carstens 38277e58496SPaul E. McKenneyconfig ARCH_WEAK_RELEASE_ACQUIRE 38377e58496SPaul E. McKenney bool 38477e58496SPaul E. McKenney 385c1d7e01dSWill Deaconconfig ARCH_WANT_IPC_PARSE_VERSION 386c1d7e01dSWill Deacon bool 387c1d7e01dSWill Deacon 388c1d7e01dSWill Deaconconfig ARCH_WANT_COMPAT_IPC_PARSE_VERSION 389c1d7e01dSWill Deacon bool 390c1d7e01dSWill Deacon 39148b25c43SChris Metcalfconfig ARCH_WANT_OLD_COMPAT_IPC 392c1d7e01dSWill Deacon select ARCH_WANT_COMPAT_IPC_PARSE_VERSION 39348b25c43SChris Metcalf bool 39448b25c43SChris Metcalf 395e2cfabdfSWill Drewryconfig HAVE_ARCH_SECCOMP_FILTER 396e2cfabdfSWill Drewry bool 397e2cfabdfSWill Drewry help 398fb0fadf9SWill Drewry An arch should select this symbol if it provides all of these things: 399bb6ea430SWill Drewry - syscall_get_arch() 400bb6ea430SWill Drewry - syscall_get_arguments() 401bb6ea430SWill Drewry - syscall_rollback() 402bb6ea430SWill Drewry - syscall_set_return_value() 403fb0fadf9SWill Drewry - SIGSYS siginfo_t support 404fb0fadf9SWill Drewry - secure_computing is called from a ptrace_event()-safe context 405fb0fadf9SWill Drewry - secure_computing return value is checked and a return value of -1 406fb0fadf9SWill Drewry results in the system call being skipped immediately. 40748dc92b9SKees Cook - seccomp syscall wired up 408e2cfabdfSWill Drewry 409e2cfabdfSWill Drewryconfig SECCOMP_FILTER 410e2cfabdfSWill Drewry def_bool y 411e2cfabdfSWill Drewry depends on HAVE_ARCH_SECCOMP_FILTER && SECCOMP && NET 412e2cfabdfSWill Drewry help 413e2cfabdfSWill Drewry Enable tasks to build secure computing environments defined 414e2cfabdfSWill Drewry in terms of Berkeley Packet Filter programs which implement 415e2cfabdfSWill Drewry task-defined system call filtering polices. 416e2cfabdfSWill Drewry 4175fb94e9cSMauro Carvalho Chehab See Documentation/userspace-api/seccomp_filter.rst for details. 418e2cfabdfSWill Drewry 419d148eac0SMasahiro Yamadaconfig HAVE_STACKPROTECTOR 42019952a92SKees Cook bool 42119952a92SKees Cook help 42219952a92SKees Cook An arch should select this symbol if: 42319952a92SKees Cook - it has implemented a stack canary (e.g. __stack_chk_guard) 42419952a92SKees Cook 4252a61f474SMasahiro Yamadaconfig CC_HAS_STACKPROTECTOR_NONE 4262a61f474SMasahiro Yamada def_bool $(cc-option,-fno-stack-protector) 4272a61f474SMasahiro Yamada 428050e9baaSLinus Torvaldsconfig STACKPROTECTOR 4292a61f474SMasahiro Yamada bool "Stack Protector buffer overflow detection" 430d148eac0SMasahiro Yamada depends on HAVE_STACKPROTECTOR 4312a61f474SMasahiro Yamada depends on $(cc-option,-fstack-protector) 4322a61f474SMasahiro Yamada default y 4338779657dSKees Cook help 4348779657dSKees Cook This option turns on the "stack-protector" GCC feature. This 43519952a92SKees Cook feature puts, at the beginning of functions, a canary value on 43619952a92SKees Cook the stack just before the return address, and validates 43719952a92SKees Cook the value just before actually returning. Stack based buffer 43819952a92SKees Cook overflows (that need to overwrite this return address) now also 43919952a92SKees Cook overwrite the canary, which gets detected and the attack is then 44019952a92SKees Cook neutralized via a kernel panic. 44119952a92SKees Cook 4428779657dSKees Cook Functions will have the stack-protector canary logic added if they 4438779657dSKees Cook have an 8-byte or larger character array on the stack. 4448779657dSKees Cook 44519952a92SKees Cook This feature requires gcc version 4.2 or above, or a distribution 4468779657dSKees Cook gcc with the feature backported ("-fstack-protector"). 4478779657dSKees Cook 4488779657dSKees Cook On an x86 "defconfig" build, this feature adds canary checks to 4498779657dSKees Cook about 3% of all kernel functions, which increases kernel code size 4508779657dSKees Cook by about 0.3%. 4518779657dSKees Cook 452050e9baaSLinus Torvaldsconfig STACKPROTECTOR_STRONG 4532a61f474SMasahiro Yamada bool "Strong Stack Protector" 454050e9baaSLinus Torvalds depends on STACKPROTECTOR 4552a61f474SMasahiro Yamada depends on $(cc-option,-fstack-protector-strong) 4562a61f474SMasahiro Yamada default y 4578779657dSKees Cook help 4588779657dSKees Cook Functions will have the stack-protector canary logic added in any 4598779657dSKees Cook of the following conditions: 4608779657dSKees Cook 4618779657dSKees Cook - local variable's address used as part of the right hand side of an 4628779657dSKees Cook assignment or function argument 4638779657dSKees Cook - local variable is an array (or union containing an array), 4648779657dSKees Cook regardless of array type or length 4658779657dSKees Cook - uses register local variables 4668779657dSKees Cook 4678779657dSKees Cook This feature requires gcc version 4.9 or above, or a distribution 4688779657dSKees Cook gcc with the feature backported ("-fstack-protector-strong"). 4698779657dSKees Cook 4708779657dSKees Cook On an x86 "defconfig" build, this feature adds canary checks to 4718779657dSKees Cook about 20% of all kernel functions, which increases the kernel code 4728779657dSKees Cook size by about 2%. 4738779657dSKees Cook 4740f60a8efSKees Cookconfig HAVE_ARCH_WITHIN_STACK_FRAMES 4750f60a8efSKees Cook bool 4760f60a8efSKees Cook help 4770f60a8efSKees Cook An architecture should select this if it can walk the kernel stack 4780f60a8efSKees Cook frames to determine if an object is part of either the arguments 4790f60a8efSKees Cook or local variables (i.e. that it excludes saved return addresses, 4800f60a8efSKees Cook and similar) by implementing an inline arch_within_stack_frames(), 4810f60a8efSKees Cook which is used by CONFIG_HARDENED_USERCOPY. 4820f60a8efSKees Cook 48391d1aa43SFrederic Weisbeckerconfig HAVE_CONTEXT_TRACKING 4842b1d5024SFrederic Weisbecker bool 4852b1d5024SFrederic Weisbecker help 48691d1aa43SFrederic Weisbecker Provide kernel/user boundaries probes necessary for subsystems 48791d1aa43SFrederic Weisbecker that need it, such as userspace RCU extended quiescent state. 48891d1aa43SFrederic Weisbecker Syscalls need to be wrapped inside user_exit()-user_enter() through 48991d1aa43SFrederic Weisbecker the slow path using TIF_NOHZ flag. Exceptions handlers must be 49091d1aa43SFrederic Weisbecker wrapped as well. Irqs are already protected inside 49191d1aa43SFrederic Weisbecker rcu_irq_enter/rcu_irq_exit() but preemption or signal handling on 49291d1aa43SFrederic Weisbecker irq exit still need to be protected. 4932b1d5024SFrederic Weisbecker 494b952741cSFrederic Weisbeckerconfig HAVE_VIRT_CPU_ACCOUNTING 495b952741cSFrederic Weisbecker bool 496b952741cSFrederic Weisbecker 49740565b5aSStanislaw Gruszkaconfig ARCH_HAS_SCALED_CPUTIME 49840565b5aSStanislaw Gruszka bool 49940565b5aSStanislaw Gruszka 500554b0004SKevin Hilmanconfig HAVE_VIRT_CPU_ACCOUNTING_GEN 501554b0004SKevin Hilman bool 502554b0004SKevin Hilman default y if 64BIT 503554b0004SKevin Hilman help 504554b0004SKevin Hilman With VIRT_CPU_ACCOUNTING_GEN, cputime_t becomes 64-bit. 505554b0004SKevin Hilman Before enabling this option, arch code must be audited 506554b0004SKevin Hilman to ensure there are no races in concurrent read/write of 507554b0004SKevin Hilman cputime_t. For example, reading/writing 64-bit cputime_t on 508554b0004SKevin Hilman some 32-bit arches may require multiple accesses, so proper 509554b0004SKevin Hilman locking is needed to protect against concurrent accesses. 510554b0004SKevin Hilman 511554b0004SKevin Hilman 512fdf9c356SFrederic Weisbeckerconfig HAVE_IRQ_TIME_ACCOUNTING 513fdf9c356SFrederic Weisbecker bool 514fdf9c356SFrederic Weisbecker help 515fdf9c356SFrederic Weisbecker Archs need to ensure they use a high enough resolution clock to 516fdf9c356SFrederic Weisbecker support irq time accounting and then call enable_sched_clock_irqtime(). 517fdf9c356SFrederic Weisbecker 51815626062SGerald Schaeferconfig HAVE_ARCH_TRANSPARENT_HUGEPAGE 51915626062SGerald Schaefer bool 52015626062SGerald Schaefer 521a00cc7d9SMatthew Wilcoxconfig HAVE_ARCH_TRANSPARENT_HUGEPAGE_PUD 522a00cc7d9SMatthew Wilcox bool 523a00cc7d9SMatthew Wilcox 5240ddab1d2SToshi Kaniconfig HAVE_ARCH_HUGE_VMAP 5250ddab1d2SToshi Kani bool 5260ddab1d2SToshi Kani 5270f8975ecSPavel Emelyanovconfig HAVE_ARCH_SOFT_DIRTY 5280f8975ecSPavel Emelyanov bool 5290f8975ecSPavel Emelyanov 530786d35d4SDavid Howellsconfig HAVE_MOD_ARCH_SPECIFIC 531786d35d4SDavid Howells bool 532786d35d4SDavid Howells help 533786d35d4SDavid Howells The arch uses struct mod_arch_specific to store data. Many arches 534786d35d4SDavid Howells just need a simple module loader without arch specific data - those 535786d35d4SDavid Howells should not enable this. 536786d35d4SDavid Howells 537786d35d4SDavid Howellsconfig MODULES_USE_ELF_RELA 538786d35d4SDavid Howells bool 539786d35d4SDavid Howells help 540786d35d4SDavid Howells Modules only use ELF RELA relocations. Modules with ELF REL 541786d35d4SDavid Howells relocations will give an error. 542786d35d4SDavid Howells 543786d35d4SDavid Howellsconfig MODULES_USE_ELF_REL 544786d35d4SDavid Howells bool 545786d35d4SDavid Howells help 546786d35d4SDavid Howells Modules only use ELF REL relocations. Modules with ELF RELA 547786d35d4SDavid Howells relocations will give an error. 548786d35d4SDavid Howells 549cc1f0274SFrederic Weisbeckerconfig HAVE_IRQ_EXIT_ON_IRQ_STACK 550cc1f0274SFrederic Weisbecker bool 551cc1f0274SFrederic Weisbecker help 552cc1f0274SFrederic Weisbecker Architecture doesn't only execute the irq handler on the irq stack 553cc1f0274SFrederic Weisbecker but also irq_exit(). This way we can process softirqs on this irq 554cc1f0274SFrederic Weisbecker stack instead of switching to a new one when we call __do_softirq() 555cc1f0274SFrederic Weisbecker in the end of an hardirq. 556cc1f0274SFrederic Weisbecker This spares a stack switch and improves cache usage on softirq 557cc1f0274SFrederic Weisbecker processing. 558cc1f0274SFrederic Weisbecker 559235a8f02SKirill A. Shutemovconfig PGTABLE_LEVELS 560235a8f02SKirill A. Shutemov int 561235a8f02SKirill A. Shutemov default 2 562235a8f02SKirill A. Shutemov 5632b68f6caSKees Cookconfig ARCH_HAS_ELF_RANDOMIZE 5642b68f6caSKees Cook bool 5652b68f6caSKees Cook help 5662b68f6caSKees Cook An architecture supports choosing randomized locations for 5672b68f6caSKees Cook stack, mmap, brk, and ET_DYN. Defined functions: 5682b68f6caSKees Cook - arch_mmap_rnd() 569204db6edSKees Cook - arch_randomize_brk() 5702b68f6caSKees Cook 571d07e2259SDaniel Cashmanconfig HAVE_ARCH_MMAP_RND_BITS 572d07e2259SDaniel Cashman bool 573d07e2259SDaniel Cashman help 574d07e2259SDaniel Cashman An arch should select this symbol if it supports setting a variable 575d07e2259SDaniel Cashman number of bits for use in establishing the base address for mmap 576d07e2259SDaniel Cashman allocations, has MMU enabled and provides values for both: 577d07e2259SDaniel Cashman - ARCH_MMAP_RND_BITS_MIN 578d07e2259SDaniel Cashman - ARCH_MMAP_RND_BITS_MAX 579d07e2259SDaniel Cashman 5805f56a5dfSJiri Slabyconfig HAVE_EXIT_THREAD 5815f56a5dfSJiri Slaby bool 5825f56a5dfSJiri Slaby help 5835f56a5dfSJiri Slaby An architecture implements exit_thread. 5845f56a5dfSJiri Slaby 585d07e2259SDaniel Cashmanconfig ARCH_MMAP_RND_BITS_MIN 586d07e2259SDaniel Cashman int 587d07e2259SDaniel Cashman 588d07e2259SDaniel Cashmanconfig ARCH_MMAP_RND_BITS_MAX 589d07e2259SDaniel Cashman int 590d07e2259SDaniel Cashman 591d07e2259SDaniel Cashmanconfig ARCH_MMAP_RND_BITS_DEFAULT 592d07e2259SDaniel Cashman int 593d07e2259SDaniel Cashman 594d07e2259SDaniel Cashmanconfig ARCH_MMAP_RND_BITS 595d07e2259SDaniel Cashman int "Number of bits to use for ASLR of mmap base address" if EXPERT 596d07e2259SDaniel Cashman range ARCH_MMAP_RND_BITS_MIN ARCH_MMAP_RND_BITS_MAX 597d07e2259SDaniel Cashman default ARCH_MMAP_RND_BITS_DEFAULT if ARCH_MMAP_RND_BITS_DEFAULT 598d07e2259SDaniel Cashman default ARCH_MMAP_RND_BITS_MIN 599d07e2259SDaniel Cashman depends on HAVE_ARCH_MMAP_RND_BITS 600d07e2259SDaniel Cashman help 601d07e2259SDaniel Cashman This value can be used to select the number of bits to use to 602d07e2259SDaniel Cashman determine the random offset to the base address of vma regions 603d07e2259SDaniel Cashman resulting from mmap allocations. This value will be bounded 604d07e2259SDaniel Cashman by the architecture's minimum and maximum supported values. 605d07e2259SDaniel Cashman 606d07e2259SDaniel Cashman This value can be changed after boot using the 607d07e2259SDaniel Cashman /proc/sys/vm/mmap_rnd_bits tunable 608d07e2259SDaniel Cashman 609d07e2259SDaniel Cashmanconfig HAVE_ARCH_MMAP_RND_COMPAT_BITS 610d07e2259SDaniel Cashman bool 611d07e2259SDaniel Cashman help 612d07e2259SDaniel Cashman An arch should select this symbol if it supports running applications 613d07e2259SDaniel Cashman in compatibility mode, supports setting a variable number of bits for 614d07e2259SDaniel Cashman use in establishing the base address for mmap allocations, has MMU 615d07e2259SDaniel Cashman enabled and provides values for both: 616d07e2259SDaniel Cashman - ARCH_MMAP_RND_COMPAT_BITS_MIN 617d07e2259SDaniel Cashman - ARCH_MMAP_RND_COMPAT_BITS_MAX 618d07e2259SDaniel Cashman 619d07e2259SDaniel Cashmanconfig ARCH_MMAP_RND_COMPAT_BITS_MIN 620d07e2259SDaniel Cashman int 621d07e2259SDaniel Cashman 622d07e2259SDaniel Cashmanconfig ARCH_MMAP_RND_COMPAT_BITS_MAX 623d07e2259SDaniel Cashman int 624d07e2259SDaniel Cashman 625d07e2259SDaniel Cashmanconfig ARCH_MMAP_RND_COMPAT_BITS_DEFAULT 626d07e2259SDaniel Cashman int 627d07e2259SDaniel Cashman 628d07e2259SDaniel Cashmanconfig ARCH_MMAP_RND_COMPAT_BITS 629d07e2259SDaniel Cashman int "Number of bits to use for ASLR of mmap base address for compatible applications" if EXPERT 630d07e2259SDaniel Cashman range ARCH_MMAP_RND_COMPAT_BITS_MIN ARCH_MMAP_RND_COMPAT_BITS_MAX 631d07e2259SDaniel Cashman default ARCH_MMAP_RND_COMPAT_BITS_DEFAULT if ARCH_MMAP_RND_COMPAT_BITS_DEFAULT 632d07e2259SDaniel Cashman default ARCH_MMAP_RND_COMPAT_BITS_MIN 633d07e2259SDaniel Cashman depends on HAVE_ARCH_MMAP_RND_COMPAT_BITS 634d07e2259SDaniel Cashman help 635d07e2259SDaniel Cashman This value can be used to select the number of bits to use to 636d07e2259SDaniel Cashman determine the random offset to the base address of vma regions 637d07e2259SDaniel Cashman resulting from mmap allocations for compatible applications This 638d07e2259SDaniel Cashman value will be bounded by the architecture's minimum and maximum 639d07e2259SDaniel Cashman supported values. 640d07e2259SDaniel Cashman 641d07e2259SDaniel Cashman This value can be changed after boot using the 642d07e2259SDaniel Cashman /proc/sys/vm/mmap_rnd_compat_bits tunable 643d07e2259SDaniel Cashman 6441b028f78SDmitry Safonovconfig HAVE_ARCH_COMPAT_MMAP_BASES 6451b028f78SDmitry Safonov bool 6461b028f78SDmitry Safonov help 6471b028f78SDmitry Safonov This allows 64bit applications to invoke 32-bit mmap() syscall 6481b028f78SDmitry Safonov and vice-versa 32-bit applications to call 64-bit mmap(). 6491b028f78SDmitry Safonov Required for applications doing different bitness syscalls. 6501b028f78SDmitry Safonov 6513033f14aSJosh Triplettconfig HAVE_COPY_THREAD_TLS 6523033f14aSJosh Triplett bool 6533033f14aSJosh Triplett help 6543033f14aSJosh Triplett Architecture provides copy_thread_tls to accept tls argument via 6553033f14aSJosh Triplett normal C parameter passing, rather than extracting the syscall 6563033f14aSJosh Triplett argument from pt_regs. 6573033f14aSJosh Triplett 658b9ab5ebbSJosh Poimboeufconfig HAVE_STACK_VALIDATION 659b9ab5ebbSJosh Poimboeuf bool 660b9ab5ebbSJosh Poimboeuf help 661b9ab5ebbSJosh Poimboeuf Architecture supports the 'objtool check' host tool command, which 662b9ab5ebbSJosh Poimboeuf performs compile-time stack metadata validation. 663b9ab5ebbSJosh Poimboeuf 664af085d90SJosh Poimboeufconfig HAVE_RELIABLE_STACKTRACE 665af085d90SJosh Poimboeuf bool 666af085d90SJosh Poimboeuf help 667af085d90SJosh Poimboeuf Architecture has a save_stack_trace_tsk_reliable() function which 668af085d90SJosh Poimboeuf only returns a stack trace if it can guarantee the trace is reliable. 669af085d90SJosh Poimboeuf 670468a9428SGeorge Spelvinconfig HAVE_ARCH_HASH 671468a9428SGeorge Spelvin bool 672468a9428SGeorge Spelvin default n 673468a9428SGeorge Spelvin help 674468a9428SGeorge Spelvin If this is set, the architecture provides an <asm/hash.h> 675468a9428SGeorge Spelvin file which provides platform-specific implementations of some 676468a9428SGeorge Spelvin functions in <linux/hash.h> or fs/namei.c. 677468a9428SGeorge Spelvin 6783a495511SWilliam Breathitt Grayconfig ISA_BUS_API 6793a495511SWilliam Breathitt Gray def_bool ISA 6803a495511SWilliam Breathitt Gray 681d2125043SAl Viro# 682d2125043SAl Viro# ABI hall of shame 683d2125043SAl Viro# 684d2125043SAl Viroconfig CLONE_BACKWARDS 685d2125043SAl Viro bool 686d2125043SAl Viro help 687d2125043SAl Viro Architecture has tls passed as the 4th argument of clone(2), 688d2125043SAl Viro not the 5th one. 689d2125043SAl Viro 690d2125043SAl Viroconfig CLONE_BACKWARDS2 691d2125043SAl Viro bool 692d2125043SAl Viro help 693d2125043SAl Viro Architecture has the first two arguments of clone(2) swapped. 694d2125043SAl Viro 695dfa9771aSMichal Simekconfig CLONE_BACKWARDS3 696dfa9771aSMichal Simek bool 697dfa9771aSMichal Simek help 698dfa9771aSMichal Simek Architecture has tls passed as the 3rd argument of clone(2), 699dfa9771aSMichal Simek not the 5th one. 700dfa9771aSMichal Simek 701eaca6eaeSAl Viroconfig ODD_RT_SIGACTION 702eaca6eaeSAl Viro bool 703eaca6eaeSAl Viro help 704eaca6eaeSAl Viro Architecture has unusual rt_sigaction(2) arguments 705eaca6eaeSAl Viro 7060a0e8cdfSAl Viroconfig OLD_SIGSUSPEND 7070a0e8cdfSAl Viro bool 7080a0e8cdfSAl Viro help 7090a0e8cdfSAl Viro Architecture has old sigsuspend(2) syscall, of one-argument variety 7100a0e8cdfSAl Viro 7110a0e8cdfSAl Viroconfig OLD_SIGSUSPEND3 7120a0e8cdfSAl Viro bool 7130a0e8cdfSAl Viro help 7140a0e8cdfSAl Viro Even weirder antique ABI - three-argument sigsuspend(2) 7150a0e8cdfSAl Viro 716495dfbf7SAl Viroconfig OLD_SIGACTION 717495dfbf7SAl Viro bool 718495dfbf7SAl Viro help 719495dfbf7SAl Viro Architecture has old sigaction(2) syscall. Nope, not the same 720495dfbf7SAl Viro as OLD_SIGSUSPEND | OLD_SIGSUSPEND3 - alpha has sigsuspend(2), 721495dfbf7SAl Viro but fairly different variant of sigaction(2), thanks to OSF/1 722495dfbf7SAl Viro compatibility... 723495dfbf7SAl Viro 724495dfbf7SAl Viroconfig COMPAT_OLD_SIGACTION 725495dfbf7SAl Viro bool 726495dfbf7SAl Viro 727d4703ddaSDeepa Dinamaniconfig 64BIT_TIME 728d4703ddaSDeepa Dinamani def_bool ARCH_HAS_64BIT_TIME 729d4703ddaSDeepa Dinamani help 730d4703ddaSDeepa Dinamani This should be selected by all architectures that need to support 731d4703ddaSDeepa Dinamani new system calls with a 64-bit time_t. This is relevant on all 32-bit 732d4703ddaSDeepa Dinamani architectures, and 64-bit architectures as part of compat syscall 733d4703ddaSDeepa Dinamani handling. 734d4703ddaSDeepa Dinamani 73517435e5fSDeepa Dinamaniconfig COMPAT_32BIT_TIME 73617435e5fSDeepa Dinamani def_bool (!64BIT && 64BIT_TIME) || COMPAT 73717435e5fSDeepa Dinamani help 73817435e5fSDeepa Dinamani This enables 32 bit time_t support in addition to 64 bit time_t support. 73917435e5fSDeepa Dinamani This is relevant on all 32-bit architectures, and 64-bit architectures 74017435e5fSDeepa Dinamani as part of compat syscall handling. 74117435e5fSDeepa Dinamani 7420d4a619bSChristoph Hellwigconfig ARCH_NO_COHERENT_DMA_MMAP 7430d4a619bSChristoph Hellwig bool 7440d4a619bSChristoph Hellwig 74587a4c375SChristoph Hellwigconfig ARCH_NO_PREEMPT 74687a4c375SChristoph Hellwig bool 74787a4c375SChristoph Hellwig 748fff7fb0bSZhaoxiu Zengconfig CPU_NO_EFFICIENT_FFS 749fff7fb0bSZhaoxiu Zeng def_bool n 750fff7fb0bSZhaoxiu Zeng 751ba14a194SAndy Lutomirskiconfig HAVE_ARCH_VMAP_STACK 752ba14a194SAndy Lutomirski def_bool n 753ba14a194SAndy Lutomirski help 754ba14a194SAndy Lutomirski An arch should select this symbol if it can support kernel stacks 755ba14a194SAndy Lutomirski in vmalloc space. This means: 756ba14a194SAndy Lutomirski 757ba14a194SAndy Lutomirski - vmalloc space must be large enough to hold many kernel stacks. 758ba14a194SAndy Lutomirski This may rule out many 32-bit architectures. 759ba14a194SAndy Lutomirski 760ba14a194SAndy Lutomirski - Stacks in vmalloc space need to work reliably. For example, if 761ba14a194SAndy Lutomirski vmap page tables are created on demand, either this mechanism 762ba14a194SAndy Lutomirski needs to work while the stack points to a virtual address with 763ba14a194SAndy Lutomirski unpopulated page tables or arch code (switch_to() and switch_mm(), 764ba14a194SAndy Lutomirski most likely) needs to ensure that the stack's page table entries 765ba14a194SAndy Lutomirski are populated before running on a possibly unpopulated stack. 766ba14a194SAndy Lutomirski 767ba14a194SAndy Lutomirski - If the stack overflows into a guard page, something reasonable 768ba14a194SAndy Lutomirski should happen. The definition of "reasonable" is flexible, but 769ba14a194SAndy Lutomirski instantly rebooting without logging anything would be unfriendly. 770ba14a194SAndy Lutomirski 771ba14a194SAndy Lutomirskiconfig VMAP_STACK 772ba14a194SAndy Lutomirski default y 773ba14a194SAndy Lutomirski bool "Use a virtually-mapped stack" 774ba14a194SAndy Lutomirski depends on HAVE_ARCH_VMAP_STACK && !KASAN 775ba14a194SAndy Lutomirski ---help--- 776ba14a194SAndy Lutomirski Enable this if you want the use virtually-mapped kernel stacks 777ba14a194SAndy Lutomirski with guard pages. This causes kernel stack overflows to be 778ba14a194SAndy Lutomirski caught immediately rather than causing difficult-to-diagnose 779ba14a194SAndy Lutomirski corruption. 780ba14a194SAndy Lutomirski 781ba14a194SAndy Lutomirski This is presently incompatible with KASAN because KASAN expects 782ba14a194SAndy Lutomirski the stack to map directly to the KASAN shadow map using a formula 783ba14a194SAndy Lutomirski that is incorrect if the stack is in vmalloc space. 784ba14a194SAndy Lutomirski 785ad21fc4fSLaura Abbottconfig ARCH_OPTIONAL_KERNEL_RWX 786ad21fc4fSLaura Abbott def_bool n 787ad21fc4fSLaura Abbott 788ad21fc4fSLaura Abbottconfig ARCH_OPTIONAL_KERNEL_RWX_DEFAULT 789ad21fc4fSLaura Abbott def_bool n 790ad21fc4fSLaura Abbott 791ad21fc4fSLaura Abbottconfig ARCH_HAS_STRICT_KERNEL_RWX 792ad21fc4fSLaura Abbott def_bool n 793ad21fc4fSLaura Abbott 7940f5bf6d0SLaura Abbottconfig STRICT_KERNEL_RWX 795ad21fc4fSLaura Abbott bool "Make kernel text and rodata read-only" if ARCH_OPTIONAL_KERNEL_RWX 796ad21fc4fSLaura Abbott depends on ARCH_HAS_STRICT_KERNEL_RWX 797ad21fc4fSLaura Abbott default !ARCH_OPTIONAL_KERNEL_RWX || ARCH_OPTIONAL_KERNEL_RWX_DEFAULT 798ad21fc4fSLaura Abbott help 799ad21fc4fSLaura Abbott If this is set, kernel text and rodata memory will be made read-only, 800ad21fc4fSLaura Abbott and non-text memory will be made non-executable. This provides 801ad21fc4fSLaura Abbott protection against certain security exploits (e.g. executing the heap 802ad21fc4fSLaura Abbott or modifying text) 803ad21fc4fSLaura Abbott 804ad21fc4fSLaura Abbott These features are considered standard security practice these days. 805ad21fc4fSLaura Abbott You should say Y here in almost all cases. 806ad21fc4fSLaura Abbott 807ad21fc4fSLaura Abbottconfig ARCH_HAS_STRICT_MODULE_RWX 808ad21fc4fSLaura Abbott def_bool n 809ad21fc4fSLaura Abbott 8100f5bf6d0SLaura Abbottconfig STRICT_MODULE_RWX 811ad21fc4fSLaura Abbott bool "Set loadable kernel module data as NX and text as RO" if ARCH_OPTIONAL_KERNEL_RWX 812ad21fc4fSLaura Abbott depends on ARCH_HAS_STRICT_MODULE_RWX && MODULES 813ad21fc4fSLaura Abbott default !ARCH_OPTIONAL_KERNEL_RWX || ARCH_OPTIONAL_KERNEL_RWX_DEFAULT 814ad21fc4fSLaura Abbott help 815ad21fc4fSLaura Abbott If this is set, module text and rodata memory will be made read-only, 816ad21fc4fSLaura Abbott and non-text memory will be made non-executable. This provides 817ad21fc4fSLaura Abbott protection against certain security exploits (e.g. writing to text) 818ad21fc4fSLaura Abbott 819ea8c64acSChristoph Hellwig# select if the architecture provides an asm/dma-direct.h header 820ea8c64acSChristoph Hellwigconfig ARCH_HAS_PHYS_TO_DMA 821ea8c64acSChristoph Hellwig bool 822ea8c64acSChristoph Hellwig 8237a46ec0eSKees Cookconfig ARCH_HAS_REFCOUNT 8247a46ec0eSKees Cook bool 8257a46ec0eSKees Cook help 8267a46ec0eSKees Cook An architecture selects this when it has implemented refcount_t 8277a46ec0eSKees Cook using open coded assembly primitives that provide an optimized 8287a46ec0eSKees Cook refcount_t implementation, possibly at the expense of some full 8297a46ec0eSKees Cook refcount state checks of CONFIG_REFCOUNT_FULL=y. 8307a46ec0eSKees Cook 8317a46ec0eSKees Cook The refcount overflow check behavior, however, must be retained. 8327a46ec0eSKees Cook Catching overflows is the primary security concern for protecting 8337a46ec0eSKees Cook against bugs in reference counts. 8347a46ec0eSKees Cook 835fd25d19fSKees Cookconfig REFCOUNT_FULL 836fd25d19fSKees Cook bool "Perform full reference count validation at the expense of speed" 837fd25d19fSKees Cook help 838fd25d19fSKees Cook Enabling this switches the refcounting infrastructure from a fast 839fd25d19fSKees Cook unchecked atomic_t implementation to a fully state checked 840fd25d19fSKees Cook implementation, which can be (slightly) slower but provides protections 841fd25d19fSKees Cook against various use-after-free conditions that can be used in 842fd25d19fSKees Cook security flaw exploits. 843fd25d19fSKees Cook 8442521f2c2SPeter Oberparleitersource "kernel/gcov/Kconfig" 84545332b1bSMasahiro Yamada 84645332b1bSMasahiro Yamadasource "scripts/gcc-plugins/Kconfig" 847fa1b5d09SLinus Torvalds 84822471e13SRandy Dunlapendmenu 849