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 36250ff18abSArd Biesheuvelconfig HAVE_ARCH_JUMP_LABEL_RELATIVE 36350ff18abSArd Biesheuvel bool 36450ff18abSArd Biesheuvel 36526723911SPeter Zijlstraconfig HAVE_RCU_TABLE_FREE 36626723911SPeter Zijlstra bool 36726723911SPeter Zijlstra 368d86564a2SPeter Zijlstraconfig HAVE_RCU_TABLE_INVALIDATE 369d86564a2SPeter Zijlstra bool 370d86564a2SPeter Zijlstra 371df013ffbSHuang Yingconfig ARCH_HAVE_NMI_SAFE_CMPXCHG 372df013ffbSHuang Ying bool 373df013ffbSHuang Ying 37443570fd2SHeiko Carstensconfig HAVE_ALIGNED_STRUCT_PAGE 37543570fd2SHeiko Carstens bool 37643570fd2SHeiko Carstens help 37743570fd2SHeiko Carstens This makes sure that struct pages are double word aligned and that 37843570fd2SHeiko Carstens e.g. the SLUB allocator can perform double word atomic operations 37943570fd2SHeiko Carstens on a struct page for better performance. However selecting this 38043570fd2SHeiko Carstens might increase the size of a struct page by a word. 38143570fd2SHeiko Carstens 3824156153cSHeiko Carstensconfig HAVE_CMPXCHG_LOCAL 3834156153cSHeiko Carstens bool 3844156153cSHeiko Carstens 3852565409fSHeiko Carstensconfig HAVE_CMPXCHG_DOUBLE 3862565409fSHeiko Carstens bool 3872565409fSHeiko Carstens 38877e58496SPaul E. McKenneyconfig ARCH_WEAK_RELEASE_ACQUIRE 38977e58496SPaul E. McKenney bool 39077e58496SPaul E. McKenney 391c1d7e01dSWill Deaconconfig ARCH_WANT_IPC_PARSE_VERSION 392c1d7e01dSWill Deacon bool 393c1d7e01dSWill Deacon 394c1d7e01dSWill Deaconconfig ARCH_WANT_COMPAT_IPC_PARSE_VERSION 395c1d7e01dSWill Deacon bool 396c1d7e01dSWill Deacon 39748b25c43SChris Metcalfconfig ARCH_WANT_OLD_COMPAT_IPC 398c1d7e01dSWill Deacon select ARCH_WANT_COMPAT_IPC_PARSE_VERSION 39948b25c43SChris Metcalf bool 40048b25c43SChris Metcalf 401e2cfabdfSWill Drewryconfig HAVE_ARCH_SECCOMP_FILTER 402e2cfabdfSWill Drewry bool 403e2cfabdfSWill Drewry help 404fb0fadf9SWill Drewry An arch should select this symbol if it provides all of these things: 405bb6ea430SWill Drewry - syscall_get_arch() 406bb6ea430SWill Drewry - syscall_get_arguments() 407bb6ea430SWill Drewry - syscall_rollback() 408bb6ea430SWill Drewry - syscall_set_return_value() 409fb0fadf9SWill Drewry - SIGSYS siginfo_t support 410fb0fadf9SWill Drewry - secure_computing is called from a ptrace_event()-safe context 411fb0fadf9SWill Drewry - secure_computing return value is checked and a return value of -1 412fb0fadf9SWill Drewry results in the system call being skipped immediately. 41348dc92b9SKees Cook - seccomp syscall wired up 414e2cfabdfSWill Drewry 415e2cfabdfSWill Drewryconfig SECCOMP_FILTER 416e2cfabdfSWill Drewry def_bool y 417e2cfabdfSWill Drewry depends on HAVE_ARCH_SECCOMP_FILTER && SECCOMP && NET 418e2cfabdfSWill Drewry help 419e2cfabdfSWill Drewry Enable tasks to build secure computing environments defined 420e2cfabdfSWill Drewry in terms of Berkeley Packet Filter programs which implement 421e2cfabdfSWill Drewry task-defined system call filtering polices. 422e2cfabdfSWill Drewry 4235fb94e9cSMauro Carvalho Chehab See Documentation/userspace-api/seccomp_filter.rst for details. 424e2cfabdfSWill Drewry 425d148eac0SMasahiro Yamadaconfig HAVE_STACKPROTECTOR 42619952a92SKees Cook bool 42719952a92SKees Cook help 42819952a92SKees Cook An arch should select this symbol if: 42919952a92SKees Cook - it has implemented a stack canary (e.g. __stack_chk_guard) 43019952a92SKees Cook 4312a61f474SMasahiro Yamadaconfig CC_HAS_STACKPROTECTOR_NONE 4322a61f474SMasahiro Yamada def_bool $(cc-option,-fno-stack-protector) 4332a61f474SMasahiro Yamada 434050e9baaSLinus Torvaldsconfig STACKPROTECTOR 4352a61f474SMasahiro Yamada bool "Stack Protector buffer overflow detection" 436d148eac0SMasahiro Yamada depends on HAVE_STACKPROTECTOR 4372a61f474SMasahiro Yamada depends on $(cc-option,-fstack-protector) 4382a61f474SMasahiro Yamada default y 4398779657dSKees Cook help 4408779657dSKees Cook This option turns on the "stack-protector" GCC feature. This 44119952a92SKees Cook feature puts, at the beginning of functions, a canary value on 44219952a92SKees Cook the stack just before the return address, and validates 44319952a92SKees Cook the value just before actually returning. Stack based buffer 44419952a92SKees Cook overflows (that need to overwrite this return address) now also 44519952a92SKees Cook overwrite the canary, which gets detected and the attack is then 44619952a92SKees Cook neutralized via a kernel panic. 44719952a92SKees Cook 4488779657dSKees Cook Functions will have the stack-protector canary logic added if they 4498779657dSKees Cook have an 8-byte or larger character array on the stack. 4508779657dSKees Cook 45119952a92SKees Cook This feature requires gcc version 4.2 or above, or a distribution 4528779657dSKees Cook gcc with the feature backported ("-fstack-protector"). 4538779657dSKees Cook 4548779657dSKees Cook On an x86 "defconfig" build, this feature adds canary checks to 4558779657dSKees Cook about 3% of all kernel functions, which increases kernel code size 4568779657dSKees Cook by about 0.3%. 4578779657dSKees Cook 458050e9baaSLinus Torvaldsconfig STACKPROTECTOR_STRONG 4592a61f474SMasahiro Yamada bool "Strong Stack Protector" 460050e9baaSLinus Torvalds depends on STACKPROTECTOR 4612a61f474SMasahiro Yamada depends on $(cc-option,-fstack-protector-strong) 4622a61f474SMasahiro Yamada default y 4638779657dSKees Cook help 4648779657dSKees Cook Functions will have the stack-protector canary logic added in any 4658779657dSKees Cook of the following conditions: 4668779657dSKees Cook 4678779657dSKees Cook - local variable's address used as part of the right hand side of an 4688779657dSKees Cook assignment or function argument 4698779657dSKees Cook - local variable is an array (or union containing an array), 4708779657dSKees Cook regardless of array type or length 4718779657dSKees Cook - uses register local variables 4728779657dSKees Cook 4738779657dSKees Cook This feature requires gcc version 4.9 or above, or a distribution 4748779657dSKees Cook gcc with the feature backported ("-fstack-protector-strong"). 4758779657dSKees Cook 4768779657dSKees Cook On an x86 "defconfig" build, this feature adds canary checks to 4778779657dSKees Cook about 20% of all kernel functions, which increases the kernel code 4788779657dSKees Cook size by about 2%. 4798779657dSKees Cook 4800f60a8efSKees Cookconfig HAVE_ARCH_WITHIN_STACK_FRAMES 4810f60a8efSKees Cook bool 4820f60a8efSKees Cook help 4830f60a8efSKees Cook An architecture should select this if it can walk the kernel stack 4840f60a8efSKees Cook frames to determine if an object is part of either the arguments 4850f60a8efSKees Cook or local variables (i.e. that it excludes saved return addresses, 4860f60a8efSKees Cook and similar) by implementing an inline arch_within_stack_frames(), 4870f60a8efSKees Cook which is used by CONFIG_HARDENED_USERCOPY. 4880f60a8efSKees Cook 48991d1aa43SFrederic Weisbeckerconfig HAVE_CONTEXT_TRACKING 4902b1d5024SFrederic Weisbecker bool 4912b1d5024SFrederic Weisbecker help 49291d1aa43SFrederic Weisbecker Provide kernel/user boundaries probes necessary for subsystems 49391d1aa43SFrederic Weisbecker that need it, such as userspace RCU extended quiescent state. 49491d1aa43SFrederic Weisbecker Syscalls need to be wrapped inside user_exit()-user_enter() through 49591d1aa43SFrederic Weisbecker the slow path using TIF_NOHZ flag. Exceptions handlers must be 49691d1aa43SFrederic Weisbecker wrapped as well. Irqs are already protected inside 49791d1aa43SFrederic Weisbecker rcu_irq_enter/rcu_irq_exit() but preemption or signal handling on 49891d1aa43SFrederic Weisbecker irq exit still need to be protected. 4992b1d5024SFrederic Weisbecker 500b952741cSFrederic Weisbeckerconfig HAVE_VIRT_CPU_ACCOUNTING 501b952741cSFrederic Weisbecker bool 502b952741cSFrederic Weisbecker 50340565b5aSStanislaw Gruszkaconfig ARCH_HAS_SCALED_CPUTIME 50440565b5aSStanislaw Gruszka bool 50540565b5aSStanislaw Gruszka 506554b0004SKevin Hilmanconfig HAVE_VIRT_CPU_ACCOUNTING_GEN 507554b0004SKevin Hilman bool 508554b0004SKevin Hilman default y if 64BIT 509554b0004SKevin Hilman help 510554b0004SKevin Hilman With VIRT_CPU_ACCOUNTING_GEN, cputime_t becomes 64-bit. 511554b0004SKevin Hilman Before enabling this option, arch code must be audited 512554b0004SKevin Hilman to ensure there are no races in concurrent read/write of 513554b0004SKevin Hilman cputime_t. For example, reading/writing 64-bit cputime_t on 514554b0004SKevin Hilman some 32-bit arches may require multiple accesses, so proper 515554b0004SKevin Hilman locking is needed to protect against concurrent accesses. 516554b0004SKevin Hilman 517554b0004SKevin Hilman 518fdf9c356SFrederic Weisbeckerconfig HAVE_IRQ_TIME_ACCOUNTING 519fdf9c356SFrederic Weisbecker bool 520fdf9c356SFrederic Weisbecker help 521fdf9c356SFrederic Weisbecker Archs need to ensure they use a high enough resolution clock to 522fdf9c356SFrederic Weisbecker support irq time accounting and then call enable_sched_clock_irqtime(). 523fdf9c356SFrederic Weisbecker 52415626062SGerald Schaeferconfig HAVE_ARCH_TRANSPARENT_HUGEPAGE 52515626062SGerald Schaefer bool 52615626062SGerald Schaefer 527a00cc7d9SMatthew Wilcoxconfig HAVE_ARCH_TRANSPARENT_HUGEPAGE_PUD 528a00cc7d9SMatthew Wilcox bool 529a00cc7d9SMatthew Wilcox 5300ddab1d2SToshi Kaniconfig HAVE_ARCH_HUGE_VMAP 5310ddab1d2SToshi Kani bool 5320ddab1d2SToshi Kani 5330f8975ecSPavel Emelyanovconfig HAVE_ARCH_SOFT_DIRTY 5340f8975ecSPavel Emelyanov bool 5350f8975ecSPavel Emelyanov 536786d35d4SDavid Howellsconfig HAVE_MOD_ARCH_SPECIFIC 537786d35d4SDavid Howells bool 538786d35d4SDavid Howells help 539786d35d4SDavid Howells The arch uses struct mod_arch_specific to store data. Many arches 540786d35d4SDavid Howells just need a simple module loader without arch specific data - those 541786d35d4SDavid Howells should not enable this. 542786d35d4SDavid Howells 543786d35d4SDavid Howellsconfig MODULES_USE_ELF_RELA 544786d35d4SDavid Howells bool 545786d35d4SDavid Howells help 546786d35d4SDavid Howells Modules only use ELF RELA relocations. Modules with ELF REL 547786d35d4SDavid Howells relocations will give an error. 548786d35d4SDavid Howells 549786d35d4SDavid Howellsconfig MODULES_USE_ELF_REL 550786d35d4SDavid Howells bool 551786d35d4SDavid Howells help 552786d35d4SDavid Howells Modules only use ELF REL relocations. Modules with ELF RELA 553786d35d4SDavid Howells relocations will give an error. 554786d35d4SDavid Howells 555cc1f0274SFrederic Weisbeckerconfig HAVE_IRQ_EXIT_ON_IRQ_STACK 556cc1f0274SFrederic Weisbecker bool 557cc1f0274SFrederic Weisbecker help 558cc1f0274SFrederic Weisbecker Architecture doesn't only execute the irq handler on the irq stack 559cc1f0274SFrederic Weisbecker but also irq_exit(). This way we can process softirqs on this irq 560cc1f0274SFrederic Weisbecker stack instead of switching to a new one when we call __do_softirq() 561cc1f0274SFrederic Weisbecker in the end of an hardirq. 562cc1f0274SFrederic Weisbecker This spares a stack switch and improves cache usage on softirq 563cc1f0274SFrederic Weisbecker processing. 564cc1f0274SFrederic Weisbecker 565235a8f02SKirill A. Shutemovconfig PGTABLE_LEVELS 566235a8f02SKirill A. Shutemov int 567235a8f02SKirill A. Shutemov default 2 568235a8f02SKirill A. Shutemov 5692b68f6caSKees Cookconfig ARCH_HAS_ELF_RANDOMIZE 5702b68f6caSKees Cook bool 5712b68f6caSKees Cook help 5722b68f6caSKees Cook An architecture supports choosing randomized locations for 5732b68f6caSKees Cook stack, mmap, brk, and ET_DYN. Defined functions: 5742b68f6caSKees Cook - arch_mmap_rnd() 575204db6edSKees Cook - arch_randomize_brk() 5762b68f6caSKees Cook 577d07e2259SDaniel Cashmanconfig HAVE_ARCH_MMAP_RND_BITS 578d07e2259SDaniel Cashman bool 579d07e2259SDaniel Cashman help 580d07e2259SDaniel Cashman An arch should select this symbol if it supports setting a variable 581d07e2259SDaniel Cashman number of bits for use in establishing the base address for mmap 582d07e2259SDaniel Cashman allocations, has MMU enabled and provides values for both: 583d07e2259SDaniel Cashman - ARCH_MMAP_RND_BITS_MIN 584d07e2259SDaniel Cashman - ARCH_MMAP_RND_BITS_MAX 585d07e2259SDaniel Cashman 5865f56a5dfSJiri Slabyconfig HAVE_EXIT_THREAD 5875f56a5dfSJiri Slaby bool 5885f56a5dfSJiri Slaby help 5895f56a5dfSJiri Slaby An architecture implements exit_thread. 5905f56a5dfSJiri Slaby 591d07e2259SDaniel Cashmanconfig ARCH_MMAP_RND_BITS_MIN 592d07e2259SDaniel Cashman int 593d07e2259SDaniel Cashman 594d07e2259SDaniel Cashmanconfig ARCH_MMAP_RND_BITS_MAX 595d07e2259SDaniel Cashman int 596d07e2259SDaniel Cashman 597d07e2259SDaniel Cashmanconfig ARCH_MMAP_RND_BITS_DEFAULT 598d07e2259SDaniel Cashman int 599d07e2259SDaniel Cashman 600d07e2259SDaniel Cashmanconfig ARCH_MMAP_RND_BITS 601d07e2259SDaniel Cashman int "Number of bits to use for ASLR of mmap base address" if EXPERT 602d07e2259SDaniel Cashman range ARCH_MMAP_RND_BITS_MIN ARCH_MMAP_RND_BITS_MAX 603d07e2259SDaniel Cashman default ARCH_MMAP_RND_BITS_DEFAULT if ARCH_MMAP_RND_BITS_DEFAULT 604d07e2259SDaniel Cashman default ARCH_MMAP_RND_BITS_MIN 605d07e2259SDaniel Cashman depends on HAVE_ARCH_MMAP_RND_BITS 606d07e2259SDaniel Cashman help 607d07e2259SDaniel Cashman This value can be used to select the number of bits to use to 608d07e2259SDaniel Cashman determine the random offset to the base address of vma regions 609d07e2259SDaniel Cashman resulting from mmap allocations. This value will be bounded 610d07e2259SDaniel Cashman by the architecture's minimum and maximum supported values. 611d07e2259SDaniel Cashman 612d07e2259SDaniel Cashman This value can be changed after boot using the 613d07e2259SDaniel Cashman /proc/sys/vm/mmap_rnd_bits tunable 614d07e2259SDaniel Cashman 615d07e2259SDaniel Cashmanconfig HAVE_ARCH_MMAP_RND_COMPAT_BITS 616d07e2259SDaniel Cashman bool 617d07e2259SDaniel Cashman help 618d07e2259SDaniel Cashman An arch should select this symbol if it supports running applications 619d07e2259SDaniel Cashman in compatibility mode, supports setting a variable number of bits for 620d07e2259SDaniel Cashman use in establishing the base address for mmap allocations, has MMU 621d07e2259SDaniel Cashman enabled and provides values for both: 622d07e2259SDaniel Cashman - ARCH_MMAP_RND_COMPAT_BITS_MIN 623d07e2259SDaniel Cashman - ARCH_MMAP_RND_COMPAT_BITS_MAX 624d07e2259SDaniel Cashman 625d07e2259SDaniel Cashmanconfig ARCH_MMAP_RND_COMPAT_BITS_MIN 626d07e2259SDaniel Cashman int 627d07e2259SDaniel Cashman 628d07e2259SDaniel Cashmanconfig ARCH_MMAP_RND_COMPAT_BITS_MAX 629d07e2259SDaniel Cashman int 630d07e2259SDaniel Cashman 631d07e2259SDaniel Cashmanconfig ARCH_MMAP_RND_COMPAT_BITS_DEFAULT 632d07e2259SDaniel Cashman int 633d07e2259SDaniel Cashman 634d07e2259SDaniel Cashmanconfig ARCH_MMAP_RND_COMPAT_BITS 635d07e2259SDaniel Cashman int "Number of bits to use for ASLR of mmap base address for compatible applications" if EXPERT 636d07e2259SDaniel Cashman range ARCH_MMAP_RND_COMPAT_BITS_MIN ARCH_MMAP_RND_COMPAT_BITS_MAX 637d07e2259SDaniel Cashman default ARCH_MMAP_RND_COMPAT_BITS_DEFAULT if ARCH_MMAP_RND_COMPAT_BITS_DEFAULT 638d07e2259SDaniel Cashman default ARCH_MMAP_RND_COMPAT_BITS_MIN 639d07e2259SDaniel Cashman depends on HAVE_ARCH_MMAP_RND_COMPAT_BITS 640d07e2259SDaniel Cashman help 641d07e2259SDaniel Cashman This value can be used to select the number of bits to use to 642d07e2259SDaniel Cashman determine the random offset to the base address of vma regions 643d07e2259SDaniel Cashman resulting from mmap allocations for compatible applications This 644d07e2259SDaniel Cashman value will be bounded by the architecture's minimum and maximum 645d07e2259SDaniel Cashman supported values. 646d07e2259SDaniel Cashman 647d07e2259SDaniel Cashman This value can be changed after boot using the 648d07e2259SDaniel Cashman /proc/sys/vm/mmap_rnd_compat_bits tunable 649d07e2259SDaniel Cashman 6501b028f78SDmitry Safonovconfig HAVE_ARCH_COMPAT_MMAP_BASES 6511b028f78SDmitry Safonov bool 6521b028f78SDmitry Safonov help 6531b028f78SDmitry Safonov This allows 64bit applications to invoke 32-bit mmap() syscall 6541b028f78SDmitry Safonov and vice-versa 32-bit applications to call 64-bit mmap(). 6551b028f78SDmitry Safonov Required for applications doing different bitness syscalls. 6561b028f78SDmitry Safonov 6573033f14aSJosh Triplettconfig HAVE_COPY_THREAD_TLS 6583033f14aSJosh Triplett bool 6593033f14aSJosh Triplett help 6603033f14aSJosh Triplett Architecture provides copy_thread_tls to accept tls argument via 6613033f14aSJosh Triplett normal C parameter passing, rather than extracting the syscall 6623033f14aSJosh Triplett argument from pt_regs. 6633033f14aSJosh Triplett 664b9ab5ebbSJosh Poimboeufconfig HAVE_STACK_VALIDATION 665b9ab5ebbSJosh Poimboeuf bool 666b9ab5ebbSJosh Poimboeuf help 667b9ab5ebbSJosh Poimboeuf Architecture supports the 'objtool check' host tool command, which 668b9ab5ebbSJosh Poimboeuf performs compile-time stack metadata validation. 669b9ab5ebbSJosh Poimboeuf 670af085d90SJosh Poimboeufconfig HAVE_RELIABLE_STACKTRACE 671af085d90SJosh Poimboeuf bool 672af085d90SJosh Poimboeuf help 673af085d90SJosh Poimboeuf Architecture has a save_stack_trace_tsk_reliable() function which 674af085d90SJosh Poimboeuf only returns a stack trace if it can guarantee the trace is reliable. 675af085d90SJosh Poimboeuf 676468a9428SGeorge Spelvinconfig HAVE_ARCH_HASH 677468a9428SGeorge Spelvin bool 678468a9428SGeorge Spelvin default n 679468a9428SGeorge Spelvin help 680468a9428SGeorge Spelvin If this is set, the architecture provides an <asm/hash.h> 681468a9428SGeorge Spelvin file which provides platform-specific implementations of some 682468a9428SGeorge Spelvin functions in <linux/hash.h> or fs/namei.c. 683468a9428SGeorge Spelvin 6843a495511SWilliam Breathitt Grayconfig ISA_BUS_API 6853a495511SWilliam Breathitt Gray def_bool ISA 6863a495511SWilliam Breathitt Gray 687d2125043SAl Viro# 688d2125043SAl Viro# ABI hall of shame 689d2125043SAl Viro# 690d2125043SAl Viroconfig CLONE_BACKWARDS 691d2125043SAl Viro bool 692d2125043SAl Viro help 693d2125043SAl Viro Architecture has tls passed as the 4th argument of clone(2), 694d2125043SAl Viro not the 5th one. 695d2125043SAl Viro 696d2125043SAl Viroconfig CLONE_BACKWARDS2 697d2125043SAl Viro bool 698d2125043SAl Viro help 699d2125043SAl Viro Architecture has the first two arguments of clone(2) swapped. 700d2125043SAl Viro 701dfa9771aSMichal Simekconfig CLONE_BACKWARDS3 702dfa9771aSMichal Simek bool 703dfa9771aSMichal Simek help 704dfa9771aSMichal Simek Architecture has tls passed as the 3rd argument of clone(2), 705dfa9771aSMichal Simek not the 5th one. 706dfa9771aSMichal Simek 707eaca6eaeSAl Viroconfig ODD_RT_SIGACTION 708eaca6eaeSAl Viro bool 709eaca6eaeSAl Viro help 710eaca6eaeSAl Viro Architecture has unusual rt_sigaction(2) arguments 711eaca6eaeSAl Viro 7120a0e8cdfSAl Viroconfig OLD_SIGSUSPEND 7130a0e8cdfSAl Viro bool 7140a0e8cdfSAl Viro help 7150a0e8cdfSAl Viro Architecture has old sigsuspend(2) syscall, of one-argument variety 7160a0e8cdfSAl Viro 7170a0e8cdfSAl Viroconfig OLD_SIGSUSPEND3 7180a0e8cdfSAl Viro bool 7190a0e8cdfSAl Viro help 7200a0e8cdfSAl Viro Even weirder antique ABI - three-argument sigsuspend(2) 7210a0e8cdfSAl Viro 722495dfbf7SAl Viroconfig OLD_SIGACTION 723495dfbf7SAl Viro bool 724495dfbf7SAl Viro help 725495dfbf7SAl Viro Architecture has old sigaction(2) syscall. Nope, not the same 726495dfbf7SAl Viro as OLD_SIGSUSPEND | OLD_SIGSUSPEND3 - alpha has sigsuspend(2), 727495dfbf7SAl Viro but fairly different variant of sigaction(2), thanks to OSF/1 728495dfbf7SAl Viro compatibility... 729495dfbf7SAl Viro 730495dfbf7SAl Viroconfig COMPAT_OLD_SIGACTION 731495dfbf7SAl Viro bool 732495dfbf7SAl Viro 733d4703ddaSDeepa Dinamaniconfig 64BIT_TIME 734d4703ddaSDeepa Dinamani def_bool ARCH_HAS_64BIT_TIME 735d4703ddaSDeepa Dinamani help 736d4703ddaSDeepa Dinamani This should be selected by all architectures that need to support 737d4703ddaSDeepa Dinamani new system calls with a 64-bit time_t. This is relevant on all 32-bit 738d4703ddaSDeepa Dinamani architectures, and 64-bit architectures as part of compat syscall 739d4703ddaSDeepa Dinamani handling. 740d4703ddaSDeepa Dinamani 74117435e5fSDeepa Dinamaniconfig COMPAT_32BIT_TIME 74217435e5fSDeepa Dinamani def_bool (!64BIT && 64BIT_TIME) || COMPAT 74317435e5fSDeepa Dinamani help 74417435e5fSDeepa Dinamani This enables 32 bit time_t support in addition to 64 bit time_t support. 74517435e5fSDeepa Dinamani This is relevant on all 32-bit architectures, and 64-bit architectures 74617435e5fSDeepa Dinamani as part of compat syscall handling. 74717435e5fSDeepa Dinamani 7480d4a619bSChristoph Hellwigconfig ARCH_NO_COHERENT_DMA_MMAP 7490d4a619bSChristoph Hellwig bool 7500d4a619bSChristoph Hellwig 75187a4c375SChristoph Hellwigconfig ARCH_NO_PREEMPT 75287a4c375SChristoph Hellwig bool 75387a4c375SChristoph Hellwig 754fff7fb0bSZhaoxiu Zengconfig CPU_NO_EFFICIENT_FFS 755fff7fb0bSZhaoxiu Zeng def_bool n 756fff7fb0bSZhaoxiu Zeng 757ba14a194SAndy Lutomirskiconfig HAVE_ARCH_VMAP_STACK 758ba14a194SAndy Lutomirski def_bool n 759ba14a194SAndy Lutomirski help 760ba14a194SAndy Lutomirski An arch should select this symbol if it can support kernel stacks 761ba14a194SAndy Lutomirski in vmalloc space. This means: 762ba14a194SAndy Lutomirski 763ba14a194SAndy Lutomirski - vmalloc space must be large enough to hold many kernel stacks. 764ba14a194SAndy Lutomirski This may rule out many 32-bit architectures. 765ba14a194SAndy Lutomirski 766ba14a194SAndy Lutomirski - Stacks in vmalloc space need to work reliably. For example, if 767ba14a194SAndy Lutomirski vmap page tables are created on demand, either this mechanism 768ba14a194SAndy Lutomirski needs to work while the stack points to a virtual address with 769ba14a194SAndy Lutomirski unpopulated page tables or arch code (switch_to() and switch_mm(), 770ba14a194SAndy Lutomirski most likely) needs to ensure that the stack's page table entries 771ba14a194SAndy Lutomirski are populated before running on a possibly unpopulated stack. 772ba14a194SAndy Lutomirski 773ba14a194SAndy Lutomirski - If the stack overflows into a guard page, something reasonable 774ba14a194SAndy Lutomirski should happen. The definition of "reasonable" is flexible, but 775ba14a194SAndy Lutomirski instantly rebooting without logging anything would be unfriendly. 776ba14a194SAndy Lutomirski 777ba14a194SAndy Lutomirskiconfig VMAP_STACK 778ba14a194SAndy Lutomirski default y 779ba14a194SAndy Lutomirski bool "Use a virtually-mapped stack" 780ba14a194SAndy Lutomirski depends on HAVE_ARCH_VMAP_STACK && !KASAN 781ba14a194SAndy Lutomirski ---help--- 782ba14a194SAndy Lutomirski Enable this if you want the use virtually-mapped kernel stacks 783ba14a194SAndy Lutomirski with guard pages. This causes kernel stack overflows to be 784ba14a194SAndy Lutomirski caught immediately rather than causing difficult-to-diagnose 785ba14a194SAndy Lutomirski corruption. 786ba14a194SAndy Lutomirski 787ba14a194SAndy Lutomirski This is presently incompatible with KASAN because KASAN expects 788ba14a194SAndy Lutomirski the stack to map directly to the KASAN shadow map using a formula 789ba14a194SAndy Lutomirski that is incorrect if the stack is in vmalloc space. 790ba14a194SAndy Lutomirski 791ad21fc4fSLaura Abbottconfig ARCH_OPTIONAL_KERNEL_RWX 792ad21fc4fSLaura Abbott def_bool n 793ad21fc4fSLaura Abbott 794ad21fc4fSLaura Abbottconfig ARCH_OPTIONAL_KERNEL_RWX_DEFAULT 795ad21fc4fSLaura Abbott def_bool n 796ad21fc4fSLaura Abbott 797ad21fc4fSLaura Abbottconfig ARCH_HAS_STRICT_KERNEL_RWX 798ad21fc4fSLaura Abbott def_bool n 799ad21fc4fSLaura Abbott 8000f5bf6d0SLaura Abbottconfig STRICT_KERNEL_RWX 801ad21fc4fSLaura Abbott bool "Make kernel text and rodata read-only" if ARCH_OPTIONAL_KERNEL_RWX 802ad21fc4fSLaura Abbott depends on ARCH_HAS_STRICT_KERNEL_RWX 803ad21fc4fSLaura Abbott default !ARCH_OPTIONAL_KERNEL_RWX || ARCH_OPTIONAL_KERNEL_RWX_DEFAULT 804ad21fc4fSLaura Abbott help 805ad21fc4fSLaura Abbott If this is set, kernel text and rodata memory will be made read-only, 806ad21fc4fSLaura Abbott and non-text memory will be made non-executable. This provides 807ad21fc4fSLaura Abbott protection against certain security exploits (e.g. executing the heap 808ad21fc4fSLaura Abbott or modifying text) 809ad21fc4fSLaura Abbott 810ad21fc4fSLaura Abbott These features are considered standard security practice these days. 811ad21fc4fSLaura Abbott You should say Y here in almost all cases. 812ad21fc4fSLaura Abbott 813ad21fc4fSLaura Abbottconfig ARCH_HAS_STRICT_MODULE_RWX 814ad21fc4fSLaura Abbott def_bool n 815ad21fc4fSLaura Abbott 8160f5bf6d0SLaura Abbottconfig STRICT_MODULE_RWX 817ad21fc4fSLaura Abbott bool "Set loadable kernel module data as NX and text as RO" if ARCH_OPTIONAL_KERNEL_RWX 818ad21fc4fSLaura Abbott depends on ARCH_HAS_STRICT_MODULE_RWX && MODULES 819ad21fc4fSLaura Abbott default !ARCH_OPTIONAL_KERNEL_RWX || ARCH_OPTIONAL_KERNEL_RWX_DEFAULT 820ad21fc4fSLaura Abbott help 821ad21fc4fSLaura Abbott If this is set, module text and rodata memory will be made read-only, 822ad21fc4fSLaura Abbott and non-text memory will be made non-executable. This provides 823ad21fc4fSLaura Abbott protection against certain security exploits (e.g. writing to text) 824ad21fc4fSLaura Abbott 825ea8c64acSChristoph Hellwig# select if the architecture provides an asm/dma-direct.h header 826ea8c64acSChristoph Hellwigconfig ARCH_HAS_PHYS_TO_DMA 827ea8c64acSChristoph Hellwig bool 828ea8c64acSChristoph Hellwig 8297a46ec0eSKees Cookconfig ARCH_HAS_REFCOUNT 8307a46ec0eSKees Cook bool 8317a46ec0eSKees Cook help 8327a46ec0eSKees Cook An architecture selects this when it has implemented refcount_t 8337a46ec0eSKees Cook using open coded assembly primitives that provide an optimized 8347a46ec0eSKees Cook refcount_t implementation, possibly at the expense of some full 8357a46ec0eSKees Cook refcount state checks of CONFIG_REFCOUNT_FULL=y. 8367a46ec0eSKees Cook 8377a46ec0eSKees Cook The refcount overflow check behavior, however, must be retained. 8387a46ec0eSKees Cook Catching overflows is the primary security concern for protecting 8397a46ec0eSKees Cook against bugs in reference counts. 8407a46ec0eSKees Cook 841fd25d19fSKees Cookconfig REFCOUNT_FULL 842fd25d19fSKees Cook bool "Perform full reference count validation at the expense of speed" 843fd25d19fSKees Cook help 844fd25d19fSKees Cook Enabling this switches the refcounting infrastructure from a fast 845fd25d19fSKees Cook unchecked atomic_t implementation to a fully state checked 846fd25d19fSKees Cook implementation, which can be (slightly) slower but provides protections 847fd25d19fSKees Cook against various use-after-free conditions that can be used in 848fd25d19fSKees Cook security flaw exploits. 849fd25d19fSKees Cook 85004f264d3SPaul Burtonconfig HAVE_ARCH_COMPILER_H 85104f264d3SPaul Burton bool 85204f264d3SPaul Burton help 85304f264d3SPaul Burton An architecture can select this if it provides an 85404f264d3SPaul Burton asm/compiler.h header that should be included after 85504f264d3SPaul Burton linux/compiler-*.h in order to override macro definitions that those 85604f264d3SPaul Burton headers generally provide. 85704f264d3SPaul Burton 858271ca788SArd Biesheuvelconfig HAVE_ARCH_PREL32_RELOCATIONS 859271ca788SArd Biesheuvel bool 860271ca788SArd Biesheuvel help 861271ca788SArd Biesheuvel May be selected by an architecture if it supports place-relative 862271ca788SArd Biesheuvel 32-bit relocations, both in the toolchain and in the module loader, 863271ca788SArd Biesheuvel in which case relative references can be used in special sections 864271ca788SArd Biesheuvel for PCI fixup, initcalls etc which are only half the size on 64 bit 865271ca788SArd Biesheuvel architectures, and don't require runtime relocation on relocatable 866271ca788SArd Biesheuvel kernels. 867271ca788SArd Biesheuvel 8682521f2c2SPeter Oberparleitersource "kernel/gcov/Kconfig" 86945332b1bSMasahiro Yamada 87045332b1bSMasahiro Yamadasource "scripts/gcc-plugins/Kconfig" 871fa1b5d09SLinus Torvalds 87222471e13SRandy Dunlapendmenu 873