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 24125e5645SMathieu Desnoyersconfig OPROFILE 25b309a294SRobert Richter tristate "OProfile system profiling" 26125e5645SMathieu Desnoyers depends on PROFILING 27125e5645SMathieu Desnoyers depends on HAVE_OPROFILE 28d69d59f4SIngo Molnar select RING_BUFFER 299a5963ebSChristian Borntraeger select RING_BUFFER_ALLOW_SWAP 30125e5645SMathieu Desnoyers help 31125e5645SMathieu Desnoyers OProfile is a profiling system capable of profiling the 32125e5645SMathieu Desnoyers whole system, include the kernel, kernel modules, libraries, 33125e5645SMathieu Desnoyers and applications. 34125e5645SMathieu Desnoyers 35125e5645SMathieu Desnoyers If unsure, say N. 36125e5645SMathieu Desnoyers 374d4036e0SJason Yehconfig OPROFILE_EVENT_MULTIPLEX 384d4036e0SJason Yeh bool "OProfile multiplexing support (EXPERIMENTAL)" 394d4036e0SJason Yeh default n 404d4036e0SJason Yeh depends on OPROFILE && X86 414d4036e0SJason Yeh help 424d4036e0SJason Yeh The number of hardware counters is limited. The multiplexing 434d4036e0SJason Yeh feature enables OProfile to gather more events than counters 444d4036e0SJason Yeh are provided by the hardware. This is realized by switching 459332ef9dSMasahiro Yamada between events at a user specified time interval. 464d4036e0SJason Yeh 474d4036e0SJason Yeh If unsure, say N. 484d4036e0SJason Yeh 49125e5645SMathieu Desnoyersconfig HAVE_OPROFILE 509ba16087SJan Beulich bool 51125e5645SMathieu Desnoyers 52dcfce4a0SRobert Richterconfig OPROFILE_NMI_TIMER 53dcfce4a0SRobert Richter def_bool y 54af9feebeSAnton Blanchard depends on PERF_EVENTS && HAVE_PERF_EVENTS_NMI && !PPC64 55dcfce4a0SRobert Richter 56125e5645SMathieu Desnoyersconfig KPROBES 57125e5645SMathieu Desnoyers bool "Kprobes" 5805ed160eSMasami Hiramatsu depends on MODULES 59125e5645SMathieu Desnoyers depends on HAVE_KPROBES 6005ed160eSMasami Hiramatsu select KALLSYMS 61125e5645SMathieu Desnoyers help 62125e5645SMathieu Desnoyers Kprobes allows you to trap at almost any kernel address and 63125e5645SMathieu Desnoyers execute a callback function. register_kprobe() establishes 64125e5645SMathieu Desnoyers a probepoint and specifies the callback. Kprobes is useful 65125e5645SMathieu Desnoyers for kernel debugging, non-intrusive instrumentation and testing. 66125e5645SMathieu Desnoyers If in doubt, say "N". 67125e5645SMathieu Desnoyers 6845f81b1cSSteven Rostedtconfig JUMP_LABEL 69c5905afbSIngo Molnar bool "Optimize very unlikely/likely branches" 7045f81b1cSSteven Rostedt depends on HAVE_ARCH_JUMP_LABEL 7145f81b1cSSteven Rostedt help 72c5905afbSIngo Molnar This option enables a transparent branch optimization that 73c5905afbSIngo Molnar makes certain almost-always-true or almost-always-false branch 74c5905afbSIngo Molnar conditions even cheaper to execute within the kernel. 7545f81b1cSSteven Rostedt 76c5905afbSIngo Molnar Certain performance-sensitive kernel code, such as trace points, 77c5905afbSIngo Molnar scheduler functionality, networking code and KVM have such 78c5905afbSIngo Molnar branches and include support for this optimization technique. 79c5905afbSIngo Molnar 80c5905afbSIngo Molnar If it is detected that the compiler has support for "asm goto", 81c5905afbSIngo Molnar the kernel will compile such branches with just a nop 82c5905afbSIngo Molnar instruction. When the condition flag is toggled to true, the 83c5905afbSIngo Molnar nop will be converted to a jump instruction to execute the 84c5905afbSIngo Molnar conditional block of instructions. 85c5905afbSIngo Molnar 86c5905afbSIngo Molnar This technique lowers overhead and stress on the branch prediction 87c5905afbSIngo Molnar of the processor and generally makes the kernel faster. The update 88c5905afbSIngo Molnar of the condition is slower, but those are always very rare. 89c5905afbSIngo Molnar 90c5905afbSIngo Molnar ( On 32-bit x86, the necessary options added to the compiler 91c5905afbSIngo Molnar flags may increase the size of the kernel slightly. ) 9245f81b1cSSteven Rostedt 931987c947SPeter Zijlstraconfig STATIC_KEYS_SELFTEST 941987c947SPeter Zijlstra bool "Static key selftest" 951987c947SPeter Zijlstra depends on JUMP_LABEL 961987c947SPeter Zijlstra help 971987c947SPeter Zijlstra Boot time self-test of the branch patching code. 981987c947SPeter Zijlstra 99afd66255SMasami Hiramatsuconfig OPTPROBES 1005cc718b9SMasami Hiramatsu def_bool y 1015cc718b9SMasami Hiramatsu depends on KPROBES && HAVE_OPTPROBES 102a30b85dfSMasami Hiramatsu select TASKS_RCU if PREEMPT 103afd66255SMasami Hiramatsu 104e7dbfe34SMasami Hiramatsuconfig KPROBES_ON_FTRACE 105e7dbfe34SMasami Hiramatsu def_bool y 106e7dbfe34SMasami Hiramatsu depends on KPROBES && HAVE_KPROBES_ON_FTRACE 107e7dbfe34SMasami Hiramatsu depends on DYNAMIC_FTRACE_WITH_REGS 108e7dbfe34SMasami Hiramatsu help 109e7dbfe34SMasami Hiramatsu If function tracer is enabled and the arch supports full 110e7dbfe34SMasami Hiramatsu passing of pt_regs to function tracing, then kprobes can 111e7dbfe34SMasami Hiramatsu optimize on top of function tracing. 112e7dbfe34SMasami Hiramatsu 1132b144498SSrikar Dronamrajuconfig UPROBES 11409294e31SDavid A. Long def_bool n 115e8f4aa60SAllen Pais depends on ARCH_SUPPORTS_UPROBES 1162b144498SSrikar Dronamraju help 1177b2d81d4SIngo Molnar Uprobes is the user-space counterpart to kprobes: they 1187b2d81d4SIngo Molnar enable instrumentation applications (such as 'perf probe') 1197b2d81d4SIngo Molnar to establish unintrusive probes in user-space binaries and 1207b2d81d4SIngo Molnar libraries, by executing handler functions when the probes 1217b2d81d4SIngo Molnar are hit by user-space applications. 1227b2d81d4SIngo Molnar 1237b2d81d4SIngo Molnar ( These probes come in the form of single-byte breakpoints, 1247b2d81d4SIngo Molnar managed by the kernel and kept transparent to the probed 1257b2d81d4SIngo Molnar application. ) 1262b144498SSrikar Dronamraju 127c19fa94aSJames Hoganconfig HAVE_64BIT_ALIGNED_ACCESS 128c19fa94aSJames Hogan def_bool 64BIT && !HAVE_EFFICIENT_UNALIGNED_ACCESS 129c19fa94aSJames Hogan help 130c19fa94aSJames Hogan Some architectures require 64 bit accesses to be 64 bit 131c19fa94aSJames Hogan aligned, which also requires structs containing 64 bit values 132c19fa94aSJames Hogan to be 64 bit aligned too. This includes some 32 bit 133c19fa94aSJames Hogan architectures which can do 64 bit accesses, as well as 64 bit 134c19fa94aSJames Hogan architectures without unaligned access. 135c19fa94aSJames Hogan 136c19fa94aSJames Hogan This symbol should be selected by an architecture if 64 bit 137c19fa94aSJames Hogan accesses are required to be 64 bit aligned in this way even 138c19fa94aSJames Hogan though it is not a 64 bit architecture. 139c19fa94aSJames Hogan 140c19fa94aSJames Hogan See Documentation/unaligned-memory-access.txt for more 141c19fa94aSJames Hogan information on the topic of unaligned memory accesses. 142c19fa94aSJames Hogan 14358340a07SJohannes Bergconfig HAVE_EFFICIENT_UNALIGNED_ACCESS 1449ba16087SJan Beulich bool 14558340a07SJohannes Berg help 14658340a07SJohannes Berg Some architectures are unable to perform unaligned accesses 14758340a07SJohannes Berg without the use of get_unaligned/put_unaligned. Others are 14858340a07SJohannes Berg unable to perform such accesses efficiently (e.g. trap on 14958340a07SJohannes Berg unaligned access and require fixing it up in the exception 15058340a07SJohannes Berg handler.) 15158340a07SJohannes Berg 15258340a07SJohannes Berg This symbol should be selected by an architecture if it can 15358340a07SJohannes Berg perform unaligned accesses efficiently to allow different 15458340a07SJohannes Berg code paths to be selected for these cases. Some network 15558340a07SJohannes Berg drivers, for example, could opt to not fix up alignment 15658340a07SJohannes Berg problems with received packets if doing so would not help 15758340a07SJohannes Berg much. 15858340a07SJohannes Berg 15958340a07SJohannes Berg See Documentation/unaligned-memory-access.txt for more 16058340a07SJohannes Berg information on the topic of unaligned memory accesses. 16158340a07SJohannes Berg 162cf66bb93SDavid Woodhouseconfig ARCH_USE_BUILTIN_BSWAP 163cf66bb93SDavid Woodhouse bool 164cf66bb93SDavid Woodhouse help 165cf66bb93SDavid Woodhouse Modern versions of GCC (since 4.4) have builtin functions 166cf66bb93SDavid Woodhouse for handling byte-swapping. Using these, instead of the old 167cf66bb93SDavid Woodhouse inline assembler that the architecture code provides in the 168cf66bb93SDavid Woodhouse __arch_bswapXX() macros, allows the compiler to see what's 169cf66bb93SDavid Woodhouse happening and offers more opportunity for optimisation. In 170cf66bb93SDavid Woodhouse particular, the compiler will be able to combine the byteswap 171cf66bb93SDavid Woodhouse with a nearby load or store and use load-and-swap or 172cf66bb93SDavid Woodhouse store-and-swap instructions if the architecture has them. It 173cf66bb93SDavid Woodhouse should almost *never* result in code which is worse than the 174cf66bb93SDavid Woodhouse hand-coded assembler in <asm/swab.h>. But just in case it 175cf66bb93SDavid Woodhouse does, the use of the builtins is optional. 176cf66bb93SDavid Woodhouse 177cf66bb93SDavid Woodhouse Any architecture with load-and-swap or store-and-swap 178cf66bb93SDavid Woodhouse instructions should set this. And it shouldn't hurt to set it 179cf66bb93SDavid Woodhouse on architectures that don't have such instructions. 180cf66bb93SDavid Woodhouse 1819edddaa2SAnanth N Mavinakayanahalliconfig KRETPROBES 1829edddaa2SAnanth N Mavinakayanahalli def_bool y 1839edddaa2SAnanth N Mavinakayanahalli depends on KPROBES && HAVE_KRETPROBES 1849edddaa2SAnanth N Mavinakayanahalli 1857c68af6eSAvi Kivityconfig USER_RETURN_NOTIFIER 1867c68af6eSAvi Kivity bool 1877c68af6eSAvi Kivity depends on HAVE_USER_RETURN_NOTIFIER 1887c68af6eSAvi Kivity help 1897c68af6eSAvi Kivity Provide a kernel-internal notification when a cpu is about to 1907c68af6eSAvi Kivity switch to user mode. 1917c68af6eSAvi Kivity 19228b2ee20SRik van Rielconfig HAVE_IOREMAP_PROT 1939ba16087SJan Beulich bool 19428b2ee20SRik van Riel 195125e5645SMathieu Desnoyersconfig HAVE_KPROBES 1969ba16087SJan Beulich bool 1979edddaa2SAnanth N Mavinakayanahalli 1989edddaa2SAnanth N Mavinakayanahalliconfig HAVE_KRETPROBES 1999ba16087SJan Beulich bool 20074bc7ceeSArthur Kepner 201afd66255SMasami Hiramatsuconfig HAVE_OPTPROBES 202afd66255SMasami Hiramatsu bool 203d314d74cSCong Wang 204e7dbfe34SMasami Hiramatsuconfig HAVE_KPROBES_ON_FTRACE 205e7dbfe34SMasami Hiramatsu bool 206e7dbfe34SMasami Hiramatsu 207540adea3SMasami Hiramatsuconfig HAVE_FUNCTION_ERROR_INJECTION 2089802d865SJosef Bacik bool 2099802d865SJosef Bacik 21042a0bb3fSPetr Mladekconfig HAVE_NMI 21142a0bb3fSPetr Mladek bool 21242a0bb3fSPetr Mladek 2131f5a4ad9SRoland McGrath# 2141f5a4ad9SRoland McGrath# An arch should select this if it provides all these things: 2151f5a4ad9SRoland McGrath# 2161f5a4ad9SRoland McGrath# task_pt_regs() in asm/processor.h or asm/ptrace.h 2171f5a4ad9SRoland McGrath# arch_has_single_step() if there is hardware single-step support 2181f5a4ad9SRoland McGrath# arch_has_block_step() if there is hardware block-step support 2191f5a4ad9SRoland McGrath# asm/syscall.h supplying asm-generic/syscall.h interface 2201f5a4ad9SRoland McGrath# linux/regset.h user_regset interfaces 2211f5a4ad9SRoland McGrath# CORE_DUMP_USE_REGSET #define'd in linux/elf.h 2221f5a4ad9SRoland McGrath# TIF_SYSCALL_TRACE calls tracehook_report_syscall_{entry,exit} 2231f5a4ad9SRoland McGrath# TIF_NOTIFY_RESUME calls tracehook_notify_resume() 2241f5a4ad9SRoland McGrath# signal delivery calls tracehook_signal_handler() 2251f5a4ad9SRoland McGrath# 2261f5a4ad9SRoland McGrathconfig HAVE_ARCH_TRACEHOOK 2279ba16087SJan Beulich bool 2281f5a4ad9SRoland McGrath 229c64be2bbSMarek Szyprowskiconfig HAVE_DMA_CONTIGUOUS 230c64be2bbSMarek Szyprowski bool 231c64be2bbSMarek Szyprowski 23229d5e047SThomas Gleixnerconfig GENERIC_SMP_IDLE_THREAD 23329d5e047SThomas Gleixner bool 23429d5e047SThomas Gleixner 235485cf5daSKevin Hilmanconfig GENERIC_IDLE_POLL_SETUP 236485cf5daSKevin Hilman bool 237485cf5daSKevin Hilman 2386974f0c4SDaniel Micayconfig ARCH_HAS_FORTIFY_SOURCE 2396974f0c4SDaniel Micay bool 2406974f0c4SDaniel Micay help 2416974f0c4SDaniel Micay An architecture should select this when it can successfully 2426974f0c4SDaniel Micay build and run with CONFIG_FORTIFY_SOURCE. 2436974f0c4SDaniel Micay 244d2852a22SDaniel Borkmann# Select if arch has all set_memory_ro/rw/x/nx() functions in asm/cacheflush.h 245d2852a22SDaniel Borkmannconfig ARCH_HAS_SET_MEMORY 246d2852a22SDaniel Borkmann bool 247d2852a22SDaniel Borkmann 2480500871fSDavid Howells# Select if arch init_task must go in the __init_task_data section 2490500871fSDavid Howellsconfig ARCH_TASK_STRUCT_ON_STACK 250a4a2eb49SThomas Gleixner bool 251a4a2eb49SThomas Gleixner 252f5e10287SThomas Gleixner# Select if arch has its private alloc_task_struct() function 253f5e10287SThomas Gleixnerconfig ARCH_TASK_STRUCT_ALLOCATOR 254f5e10287SThomas Gleixner bool 255f5e10287SThomas Gleixner 2565905429aSKees Cookconfig HAVE_ARCH_THREAD_STRUCT_WHITELIST 2575905429aSKees Cook bool 2585905429aSKees Cook depends on !ARCH_TASK_STRUCT_ALLOCATOR 2595905429aSKees Cook help 2605905429aSKees Cook An architecture should select this to provide hardened usercopy 2615905429aSKees Cook knowledge about what region of the thread_struct should be 2625905429aSKees Cook whitelisted for copying to userspace. Normally this is only the 2635905429aSKees Cook FPU registers. Specifically, arch_thread_struct_whitelist() 2645905429aSKees Cook should be implemented. Without this, the entire thread_struct 2655905429aSKees Cook field in task_struct will be left whitelisted. 2665905429aSKees Cook 267b235beeaSLinus Torvalds# Select if arch has its private alloc_thread_stack() function 268b235beeaSLinus Torvaldsconfig ARCH_THREAD_STACK_ALLOCATOR 269f5e10287SThomas Gleixner bool 270f5e10287SThomas Gleixner 2715aaeb5c0SIngo Molnar# Select if arch wants to size task_struct dynamically via arch_task_struct_size: 2725aaeb5c0SIngo Molnarconfig ARCH_WANTS_DYNAMIC_TASK_STRUCT 2735aaeb5c0SIngo Molnar bool 2745aaeb5c0SIngo Molnar 275f850c30cSHeiko Carstensconfig HAVE_REGS_AND_STACK_ACCESS_API 276f850c30cSHeiko Carstens bool 277e01292b1SHeiko Carstens help 278e01292b1SHeiko Carstens This symbol should be selected by an architecure if it supports 279e01292b1SHeiko Carstens the API needed to access registers and stack entries from pt_regs, 280e01292b1SHeiko Carstens declared in asm/ptrace.h 281e01292b1SHeiko Carstens For example the kprobes-based event tracer needs this API. 282f850c30cSHeiko Carstens 283d7822b1eSMathieu Desnoyersconfig HAVE_RSEQ 284d7822b1eSMathieu Desnoyers bool 285d7822b1eSMathieu Desnoyers depends on HAVE_REGS_AND_STACK_ACCESS_API 286d7822b1eSMathieu Desnoyers help 287d7822b1eSMathieu Desnoyers This symbol should be selected by an architecture if it 288d7822b1eSMathieu Desnoyers supports an implementation of restartable sequences. 289d7822b1eSMathieu Desnoyers 2909483a578SDavid Brownellconfig HAVE_CLK 2919ba16087SJan Beulich bool 2929483a578SDavid Brownell help 2939483a578SDavid Brownell The <linux/clk.h> calls support software clock gating and 2949483a578SDavid Brownell thus are a key power management tool on many systems. 2959483a578SDavid Brownell 29662a038d3SK.Prasadconfig HAVE_HW_BREAKPOINT 29762a038d3SK.Prasad bool 29899e8c5a3SFrederic Weisbecker depends on PERF_EVENTS 29962a038d3SK.Prasad 3000102752eSFrederic Weisbeckerconfig HAVE_MIXED_BREAKPOINTS_REGS 3010102752eSFrederic Weisbecker bool 3020102752eSFrederic Weisbecker depends on HAVE_HW_BREAKPOINT 3030102752eSFrederic Weisbecker help 3040102752eSFrederic Weisbecker Depending on the arch implementation of hardware breakpoints, 3050102752eSFrederic Weisbecker some of them have separate registers for data and instruction 3060102752eSFrederic Weisbecker breakpoints addresses, others have mixed registers to store 3070102752eSFrederic Weisbecker them but define the access type in a control register. 3080102752eSFrederic Weisbecker Select this option if your arch implements breakpoints under the 3090102752eSFrederic Weisbecker latter fashion. 3100102752eSFrederic Weisbecker 3117c68af6eSAvi Kivityconfig HAVE_USER_RETURN_NOTIFIER 3127c68af6eSAvi Kivity bool 313a1922ed6SIngo Molnar 314c01d4323SFrederic Weisbeckerconfig HAVE_PERF_EVENTS_NMI 315c01d4323SFrederic Weisbecker bool 31623637d47SFrederic Weisbecker help 31723637d47SFrederic Weisbecker System hardware can generate an NMI using the perf event 31823637d47SFrederic Weisbecker subsystem. Also has support for calculating CPU cycle events 31923637d47SFrederic Weisbecker to determine how many clock cycles in a given period. 320c01d4323SFrederic Weisbecker 32105a4a952SNicholas Pigginconfig HAVE_HARDLOCKUP_DETECTOR_PERF 32205a4a952SNicholas Piggin bool 32305a4a952SNicholas Piggin depends on HAVE_PERF_EVENTS_NMI 32405a4a952SNicholas Piggin help 32505a4a952SNicholas Piggin The arch chooses to use the generic perf-NMI-based hardlockup 32605a4a952SNicholas Piggin detector. Must define HAVE_PERF_EVENTS_NMI. 32705a4a952SNicholas Piggin 32805a4a952SNicholas Pigginconfig HAVE_NMI_WATCHDOG 32905a4a952SNicholas Piggin depends on HAVE_NMI 33005a4a952SNicholas Piggin bool 33105a4a952SNicholas Piggin help 33205a4a952SNicholas Piggin The arch provides a low level NMI watchdog. It provides 33305a4a952SNicholas Piggin asm/nmi.h, and defines its own arch_touch_nmi_watchdog(). 33405a4a952SNicholas Piggin 33505a4a952SNicholas Pigginconfig HAVE_HARDLOCKUP_DETECTOR_ARCH 33605a4a952SNicholas Piggin bool 33705a4a952SNicholas Piggin select HAVE_NMI_WATCHDOG 33805a4a952SNicholas Piggin help 33905a4a952SNicholas Piggin The arch chooses to provide its own hardlockup detector, which is 34005a4a952SNicholas Piggin a superset of the HAVE_NMI_WATCHDOG. It also conforms to config 34105a4a952SNicholas Piggin interfaces and parameters provided by hardlockup detector subsystem. 34205a4a952SNicholas Piggin 343c5e63197SJiri Olsaconfig HAVE_PERF_REGS 344c5e63197SJiri Olsa bool 345c5e63197SJiri Olsa help 346c5e63197SJiri Olsa Support selective register dumps for perf events. This includes 347c5e63197SJiri Olsa bit-mapping of each registers and a unique architecture id. 348c5e63197SJiri Olsa 349c5ebcedbSJiri Olsaconfig HAVE_PERF_USER_STACK_DUMP 350c5ebcedbSJiri Olsa bool 351c5ebcedbSJiri Olsa help 352c5ebcedbSJiri Olsa Support user stack dumps for perf event samples. This needs 353c5ebcedbSJiri Olsa access to the user stack pointer which is not unified across 354c5ebcedbSJiri Olsa architectures. 355c5ebcedbSJiri Olsa 356bf5438fcSJason Baronconfig HAVE_ARCH_JUMP_LABEL 357bf5438fcSJason Baron bool 358bf5438fcSJason Baron 35926723911SPeter Zijlstraconfig HAVE_RCU_TABLE_FREE 36026723911SPeter Zijlstra bool 36126723911SPeter Zijlstra 362df013ffbSHuang Yingconfig ARCH_HAVE_NMI_SAFE_CMPXCHG 363df013ffbSHuang Ying bool 364df013ffbSHuang Ying 36543570fd2SHeiko Carstensconfig HAVE_ALIGNED_STRUCT_PAGE 36643570fd2SHeiko Carstens bool 36743570fd2SHeiko Carstens help 36843570fd2SHeiko Carstens This makes sure that struct pages are double word aligned and that 36943570fd2SHeiko Carstens e.g. the SLUB allocator can perform double word atomic operations 37043570fd2SHeiko Carstens on a struct page for better performance. However selecting this 37143570fd2SHeiko Carstens might increase the size of a struct page by a word. 37243570fd2SHeiko Carstens 3734156153cSHeiko Carstensconfig HAVE_CMPXCHG_LOCAL 3744156153cSHeiko Carstens bool 3754156153cSHeiko Carstens 3762565409fSHeiko Carstensconfig HAVE_CMPXCHG_DOUBLE 3772565409fSHeiko Carstens bool 3782565409fSHeiko Carstens 37977e58496SPaul E. McKenneyconfig ARCH_WEAK_RELEASE_ACQUIRE 38077e58496SPaul E. McKenney bool 38177e58496SPaul E. McKenney 382c1d7e01dSWill Deaconconfig ARCH_WANT_IPC_PARSE_VERSION 383c1d7e01dSWill Deacon bool 384c1d7e01dSWill Deacon 385c1d7e01dSWill Deaconconfig ARCH_WANT_COMPAT_IPC_PARSE_VERSION 386c1d7e01dSWill Deacon bool 387c1d7e01dSWill Deacon 38848b25c43SChris Metcalfconfig ARCH_WANT_OLD_COMPAT_IPC 389c1d7e01dSWill Deacon select ARCH_WANT_COMPAT_IPC_PARSE_VERSION 39048b25c43SChris Metcalf bool 39148b25c43SChris Metcalf 392e2cfabdfSWill Drewryconfig HAVE_ARCH_SECCOMP_FILTER 393e2cfabdfSWill Drewry bool 394e2cfabdfSWill Drewry help 395fb0fadf9SWill Drewry An arch should select this symbol if it provides all of these things: 396bb6ea430SWill Drewry - syscall_get_arch() 397bb6ea430SWill Drewry - syscall_get_arguments() 398bb6ea430SWill Drewry - syscall_rollback() 399bb6ea430SWill Drewry - syscall_set_return_value() 400fb0fadf9SWill Drewry - SIGSYS siginfo_t support 401fb0fadf9SWill Drewry - secure_computing is called from a ptrace_event()-safe context 402fb0fadf9SWill Drewry - secure_computing return value is checked and a return value of -1 403fb0fadf9SWill Drewry results in the system call being skipped immediately. 40448dc92b9SKees Cook - seccomp syscall wired up 405e2cfabdfSWill Drewry 406e2cfabdfSWill Drewryconfig SECCOMP_FILTER 407e2cfabdfSWill Drewry def_bool y 408e2cfabdfSWill Drewry depends on HAVE_ARCH_SECCOMP_FILTER && SECCOMP && NET 409e2cfabdfSWill Drewry help 410e2cfabdfSWill Drewry Enable tasks to build secure computing environments defined 411e2cfabdfSWill Drewry in terms of Berkeley Packet Filter programs which implement 412e2cfabdfSWill Drewry task-defined system call filtering polices. 413e2cfabdfSWill Drewry 4145fb94e9cSMauro Carvalho Chehab See Documentation/userspace-api/seccomp_filter.rst for details. 415e2cfabdfSWill Drewry 41659f53855SMasahiro Yamadapreferred-plugin-hostcc := $(if-success,[ $(gcc-version) -ge 40800 ],$(HOSTCXX),$(HOSTCC)) 41759f53855SMasahiro Yamada 41859f53855SMasahiro Yamadaconfig PLUGIN_HOSTCC 41959f53855SMasahiro Yamada string 42059f53855SMasahiro Yamada default "$(shell,$(srctree)/scripts/gcc-plugin.sh "$(preferred-plugin-hostcc)" "$(HOSTCXX)" "$(CC)")" 42159f53855SMasahiro Yamada help 42259f53855SMasahiro Yamada Host compiler used to build GCC plugins. This can be $(HOSTCXX), 42359f53855SMasahiro Yamada $(HOSTCC), or a null string if GCC plugin is unsupported. 42459f53855SMasahiro Yamada 4256b90bd4bSEmese Revfyconfig HAVE_GCC_PLUGINS 4266b90bd4bSEmese Revfy bool 4276b90bd4bSEmese Revfy help 4286b90bd4bSEmese Revfy An arch should select this symbol if it supports building with 4296b90bd4bSEmese Revfy GCC plugins. 4306b90bd4bSEmese Revfy 4316b90bd4bSEmese Revfymenuconfig GCC_PLUGINS 4326b90bd4bSEmese Revfy bool "GCC plugins" 4336b90bd4bSEmese Revfy depends on HAVE_GCC_PLUGINS 43459f53855SMasahiro Yamada depends on PLUGIN_HOSTCC != "" 4356b90bd4bSEmese Revfy help 4366b90bd4bSEmese Revfy GCC plugins are loadable modules that provide extra features to the 4376b90bd4bSEmese Revfy compiler. They are useful for runtime instrumentation and static analysis. 4386b90bd4bSEmese Revfy 4396b90bd4bSEmese Revfy See Documentation/gcc-plugins.txt for details. 4406b90bd4bSEmese Revfy 4410dae776cSEmese Revfyconfig GCC_PLUGIN_CYC_COMPLEXITY 442215e2aa6SKees Cook bool "Compute the cyclomatic complexity of a function" if EXPERT 4430dae776cSEmese Revfy depends on GCC_PLUGINS 4441658dceeSMasahiro Yamada depends on !COMPILE_TEST # too noisy 4450dae776cSEmese Revfy help 4460dae776cSEmese Revfy The complexity M of a function's control flow graph is defined as: 4470dae776cSEmese Revfy M = E - N + 2P 4480dae776cSEmese Revfy where 4490dae776cSEmese Revfy 4500dae776cSEmese Revfy E = the number of edges 4510dae776cSEmese Revfy N = the number of nodes 4520dae776cSEmese Revfy P = the number of connected components (exit nodes). 4530dae776cSEmese Revfy 454215e2aa6SKees Cook Enabling this plugin reports the complexity to stderr during the 455215e2aa6SKees Cook build. It mainly serves as a simple example of how to create a 456215e2aa6SKees Cook gcc plugin for the kernel. 457215e2aa6SKees Cook 458543c37cbSEmese Revfyconfig GCC_PLUGIN_SANCOV 459543c37cbSEmese Revfy bool 460543c37cbSEmese Revfy depends on GCC_PLUGINS 461543c37cbSEmese Revfy help 462543c37cbSEmese Revfy This plugin inserts a __sanitizer_cov_trace_pc() call at the start of 463543c37cbSEmese Revfy basic blocks. It supports all gcc versions with plugin support (from 464543c37cbSEmese Revfy gcc-4.5 on). It is based on the commit "Add fuzzing coverage support" 465543c37cbSEmese Revfy by Dmitry Vyukov <dvyukov@google.com>. 466543c37cbSEmese Revfy 46738addce8SEmese Revfyconfig GCC_PLUGIN_LATENT_ENTROPY 46838addce8SEmese Revfy bool "Generate some entropy during boot and runtime" 46938addce8SEmese Revfy depends on GCC_PLUGINS 47038addce8SEmese Revfy help 47138addce8SEmese Revfy By saying Y here the kernel will instrument some kernel code to 47238addce8SEmese Revfy extract some entropy from both original and artificially created 47338addce8SEmese Revfy program state. This will help especially embedded systems where 47438addce8SEmese Revfy there is little 'natural' source of entropy normally. The cost 47538addce8SEmese Revfy is some slowdown of the boot process (about 0.5%) and fork and 47638addce8SEmese Revfy irq processing. 47738addce8SEmese Revfy 47838addce8SEmese Revfy Note that entropy extracted this way is not cryptographically 47938addce8SEmese Revfy secure! 48038addce8SEmese Revfy 48138addce8SEmese Revfy This plugin was ported from grsecurity/PaX. More information at: 48238addce8SEmese Revfy * https://grsecurity.net/ 48338addce8SEmese Revfy * https://pax.grsecurity.net/ 48438addce8SEmese Revfy 485c61f13eaSKees Cookconfig GCC_PLUGIN_STRUCTLEAK 486c61f13eaSKees Cook bool "Force initialization of variables containing userspace addresses" 487c61f13eaSKees Cook depends on GCC_PLUGINS 488c9cf87eaSDmitry Vyukov # Currently STRUCTLEAK inserts initialization out of live scope of 489c9cf87eaSDmitry Vyukov # variables from KASAN point of view. This leads to KASAN false 490c9cf87eaSDmitry Vyukov # positive reports. Prohibit this combination for now. 491c9cf87eaSDmitry Vyukov depends on !KASAN_EXTRA 492c61f13eaSKees Cook help 493f136e090SJean Delvare This plugin zero-initializes any structures containing a 494c61f13eaSKees Cook __user attribute. This can prevent some classes of information 495c61f13eaSKees Cook exposures. 496c61f13eaSKees Cook 497c61f13eaSKees Cook This plugin was ported from grsecurity/PaX. More information at: 498c61f13eaSKees Cook * https://grsecurity.net/ 499c61f13eaSKees Cook * https://pax.grsecurity.net/ 500c61f13eaSKees Cook 501f7dd2507SArd Biesheuvelconfig GCC_PLUGIN_STRUCTLEAK_BYREF_ALL 502f7dd2507SArd Biesheuvel bool "Force initialize all struct type variables passed by reference" 503f7dd2507SArd Biesheuvel depends on GCC_PLUGIN_STRUCTLEAK 504caa91ba5SMasahiro Yamada depends on !COMPILE_TEST 505f7dd2507SArd Biesheuvel help 506f7dd2507SArd Biesheuvel Zero initialize any struct type local variable that may be passed by 507f7dd2507SArd Biesheuvel reference without having been initialized. 508f7dd2507SArd Biesheuvel 509c61f13eaSKees Cookconfig GCC_PLUGIN_STRUCTLEAK_VERBOSE 510c61f13eaSKees Cook bool "Report forcefully initialized variables" 511c61f13eaSKees Cook depends on GCC_PLUGIN_STRUCTLEAK 5121658dceeSMasahiro Yamada depends on !COMPILE_TEST # too noisy 513c61f13eaSKees Cook help 514c61f13eaSKees Cook This option will cause a warning to be printed each time the 515c61f13eaSKees Cook structleak plugin finds a variable it thinks needs to be 516c61f13eaSKees Cook initialized. Since not all existing initializers are detected 517c61f13eaSKees Cook by the plugin, this can produce false positive warnings. 518c61f13eaSKees Cook 519313dd1b6SKees Cookconfig GCC_PLUGIN_RANDSTRUCT 520313dd1b6SKees Cook bool "Randomize layout of sensitive kernel structures" 521313dd1b6SKees Cook depends on GCC_PLUGINS 522313dd1b6SKees Cook select MODVERSIONS if MODULES 523313dd1b6SKees Cook help 5249225331bSKees Cook If you say Y here, the layouts of structures that are entirely 5259225331bSKees Cook function pointers (and have not been manually annotated with 5269225331bSKees Cook __no_randomize_layout), or structures that have been explicitly 5279225331bSKees Cook marked with __randomize_layout, will be randomized at compile-time. 5289225331bSKees Cook This can introduce the requirement of an additional information 5299225331bSKees Cook exposure vulnerability for exploits targeting these structure 5309225331bSKees Cook types. 531313dd1b6SKees Cook 532313dd1b6SKees Cook Enabling this feature will introduce some performance impact, 533313dd1b6SKees Cook slightly increase memory usage, and prevent the use of forensic 534313dd1b6SKees Cook tools like Volatility against the system (unless the kernel 535313dd1b6SKees Cook source tree isn't cleaned after kernel installation). 536313dd1b6SKees Cook 537313dd1b6SKees Cook The seed used for compilation is located at 538313dd1b6SKees Cook scripts/gcc-plgins/randomize_layout_seed.h. It remains after 539313dd1b6SKees Cook a make clean to allow for external modules to be compiled with 540313dd1b6SKees Cook the existing seed and will be removed by a make mrproper or 541313dd1b6SKees Cook make distclean. 542313dd1b6SKees Cook 543313dd1b6SKees Cook Note that the implementation requires gcc 4.7 or newer. 544313dd1b6SKees Cook 545313dd1b6SKees Cook This plugin was ported from grsecurity/PaX. More information at: 546313dd1b6SKees Cook * https://grsecurity.net/ 547313dd1b6SKees Cook * https://pax.grsecurity.net/ 548313dd1b6SKees Cook 549313dd1b6SKees Cookconfig GCC_PLUGIN_RANDSTRUCT_PERFORMANCE 550313dd1b6SKees Cook bool "Use cacheline-aware structure randomization" 551313dd1b6SKees Cook depends on GCC_PLUGIN_RANDSTRUCT 5521658dceeSMasahiro Yamada depends on !COMPILE_TEST # do not reduce test coverage 553313dd1b6SKees Cook help 554313dd1b6SKees Cook If you say Y here, the RANDSTRUCT randomization will make a 555313dd1b6SKees Cook best effort at restricting randomization to cacheline-sized 556313dd1b6SKees Cook groups of elements. It will further not randomize bitfields 557313dd1b6SKees Cook in structures. This reduces the performance hit of RANDSTRUCT 558313dd1b6SKees Cook at the cost of weakened randomization. 559313dd1b6SKees Cook 560d148eac0SMasahiro Yamadaconfig HAVE_STACKPROTECTOR 56119952a92SKees Cook bool 56219952a92SKees Cook help 56319952a92SKees Cook An arch should select this symbol if: 56419952a92SKees Cook - it has implemented a stack canary (e.g. __stack_chk_guard) 56519952a92SKees Cook 5662a61f474SMasahiro Yamadaconfig CC_HAS_STACKPROTECTOR_NONE 5672a61f474SMasahiro Yamada def_bool $(cc-option,-fno-stack-protector) 5682a61f474SMasahiro Yamada 569050e9baaSLinus Torvaldsconfig STACKPROTECTOR 5702a61f474SMasahiro Yamada bool "Stack Protector buffer overflow detection" 571d148eac0SMasahiro Yamada depends on HAVE_STACKPROTECTOR 5722a61f474SMasahiro Yamada depends on $(cc-option,-fstack-protector) 5732a61f474SMasahiro Yamada default y 5748779657dSKees Cook help 5758779657dSKees Cook This option turns on the "stack-protector" GCC feature. This 57619952a92SKees Cook feature puts, at the beginning of functions, a canary value on 57719952a92SKees Cook the stack just before the return address, and validates 57819952a92SKees Cook the value just before actually returning. Stack based buffer 57919952a92SKees Cook overflows (that need to overwrite this return address) now also 58019952a92SKees Cook overwrite the canary, which gets detected and the attack is then 58119952a92SKees Cook neutralized via a kernel panic. 58219952a92SKees Cook 5838779657dSKees Cook Functions will have the stack-protector canary logic added if they 5848779657dSKees Cook have an 8-byte or larger character array on the stack. 5858779657dSKees Cook 58619952a92SKees Cook This feature requires gcc version 4.2 or above, or a distribution 5878779657dSKees Cook gcc with the feature backported ("-fstack-protector"). 5888779657dSKees Cook 5898779657dSKees Cook On an x86 "defconfig" build, this feature adds canary checks to 5908779657dSKees Cook about 3% of all kernel functions, which increases kernel code size 5918779657dSKees Cook by about 0.3%. 5928779657dSKees Cook 593050e9baaSLinus Torvaldsconfig STACKPROTECTOR_STRONG 5942a61f474SMasahiro Yamada bool "Strong Stack Protector" 595050e9baaSLinus Torvalds depends on STACKPROTECTOR 5962a61f474SMasahiro Yamada depends on $(cc-option,-fstack-protector-strong) 5972a61f474SMasahiro Yamada default y 5988779657dSKees Cook help 5998779657dSKees Cook Functions will have the stack-protector canary logic added in any 6008779657dSKees Cook of the following conditions: 6018779657dSKees Cook 6028779657dSKees Cook - local variable's address used as part of the right hand side of an 6038779657dSKees Cook assignment or function argument 6048779657dSKees Cook - local variable is an array (or union containing an array), 6058779657dSKees Cook regardless of array type or length 6068779657dSKees Cook - uses register local variables 6078779657dSKees Cook 6088779657dSKees Cook This feature requires gcc version 4.9 or above, or a distribution 6098779657dSKees Cook gcc with the feature backported ("-fstack-protector-strong"). 6108779657dSKees Cook 6118779657dSKees Cook On an x86 "defconfig" build, this feature adds canary checks to 6128779657dSKees Cook about 20% of all kernel functions, which increases the kernel code 6138779657dSKees Cook size by about 2%. 6148779657dSKees Cook 6150f60a8efSKees Cookconfig HAVE_ARCH_WITHIN_STACK_FRAMES 6160f60a8efSKees Cook bool 6170f60a8efSKees Cook help 6180f60a8efSKees Cook An architecture should select this if it can walk the kernel stack 6190f60a8efSKees Cook frames to determine if an object is part of either the arguments 6200f60a8efSKees Cook or local variables (i.e. that it excludes saved return addresses, 6210f60a8efSKees Cook and similar) by implementing an inline arch_within_stack_frames(), 6220f60a8efSKees Cook which is used by CONFIG_HARDENED_USERCOPY. 6230f60a8efSKees Cook 62491d1aa43SFrederic Weisbeckerconfig HAVE_CONTEXT_TRACKING 6252b1d5024SFrederic Weisbecker bool 6262b1d5024SFrederic Weisbecker help 62791d1aa43SFrederic Weisbecker Provide kernel/user boundaries probes necessary for subsystems 62891d1aa43SFrederic Weisbecker that need it, such as userspace RCU extended quiescent state. 62991d1aa43SFrederic Weisbecker Syscalls need to be wrapped inside user_exit()-user_enter() through 63091d1aa43SFrederic Weisbecker the slow path using TIF_NOHZ flag. Exceptions handlers must be 63191d1aa43SFrederic Weisbecker wrapped as well. Irqs are already protected inside 63291d1aa43SFrederic Weisbecker rcu_irq_enter/rcu_irq_exit() but preemption or signal handling on 63391d1aa43SFrederic Weisbecker irq exit still need to be protected. 6342b1d5024SFrederic Weisbecker 635b952741cSFrederic Weisbeckerconfig HAVE_VIRT_CPU_ACCOUNTING 636b952741cSFrederic Weisbecker bool 637b952741cSFrederic Weisbecker 63840565b5aSStanislaw Gruszkaconfig ARCH_HAS_SCALED_CPUTIME 63940565b5aSStanislaw Gruszka bool 64040565b5aSStanislaw Gruszka 641554b0004SKevin Hilmanconfig HAVE_VIRT_CPU_ACCOUNTING_GEN 642554b0004SKevin Hilman bool 643554b0004SKevin Hilman default y if 64BIT 644554b0004SKevin Hilman help 645554b0004SKevin Hilman With VIRT_CPU_ACCOUNTING_GEN, cputime_t becomes 64-bit. 646554b0004SKevin Hilman Before enabling this option, arch code must be audited 647554b0004SKevin Hilman to ensure there are no races in concurrent read/write of 648554b0004SKevin Hilman cputime_t. For example, reading/writing 64-bit cputime_t on 649554b0004SKevin Hilman some 32-bit arches may require multiple accesses, so proper 650554b0004SKevin Hilman locking is needed to protect against concurrent accesses. 651554b0004SKevin Hilman 652554b0004SKevin Hilman 653fdf9c356SFrederic Weisbeckerconfig HAVE_IRQ_TIME_ACCOUNTING 654fdf9c356SFrederic Weisbecker bool 655fdf9c356SFrederic Weisbecker help 656fdf9c356SFrederic Weisbecker Archs need to ensure they use a high enough resolution clock to 657fdf9c356SFrederic Weisbecker support irq time accounting and then call enable_sched_clock_irqtime(). 658fdf9c356SFrederic Weisbecker 65915626062SGerald Schaeferconfig HAVE_ARCH_TRANSPARENT_HUGEPAGE 66015626062SGerald Schaefer bool 66115626062SGerald Schaefer 662a00cc7d9SMatthew Wilcoxconfig HAVE_ARCH_TRANSPARENT_HUGEPAGE_PUD 663a00cc7d9SMatthew Wilcox bool 664a00cc7d9SMatthew Wilcox 6650ddab1d2SToshi Kaniconfig HAVE_ARCH_HUGE_VMAP 6660ddab1d2SToshi Kani bool 6670ddab1d2SToshi Kani 6680f8975ecSPavel Emelyanovconfig HAVE_ARCH_SOFT_DIRTY 6690f8975ecSPavel Emelyanov bool 6700f8975ecSPavel Emelyanov 671786d35d4SDavid Howellsconfig HAVE_MOD_ARCH_SPECIFIC 672786d35d4SDavid Howells bool 673786d35d4SDavid Howells help 674786d35d4SDavid Howells The arch uses struct mod_arch_specific to store data. Many arches 675786d35d4SDavid Howells just need a simple module loader without arch specific data - those 676786d35d4SDavid Howells should not enable this. 677786d35d4SDavid Howells 678786d35d4SDavid Howellsconfig MODULES_USE_ELF_RELA 679786d35d4SDavid Howells bool 680786d35d4SDavid Howells help 681786d35d4SDavid Howells Modules only use ELF RELA relocations. Modules with ELF REL 682786d35d4SDavid Howells relocations will give an error. 683786d35d4SDavid Howells 684786d35d4SDavid Howellsconfig MODULES_USE_ELF_REL 685786d35d4SDavid Howells bool 686786d35d4SDavid Howells help 687786d35d4SDavid Howells Modules only use ELF REL relocations. Modules with ELF RELA 688786d35d4SDavid Howells relocations will give an error. 689786d35d4SDavid Howells 690cc1f0274SFrederic Weisbeckerconfig HAVE_IRQ_EXIT_ON_IRQ_STACK 691cc1f0274SFrederic Weisbecker bool 692cc1f0274SFrederic Weisbecker help 693cc1f0274SFrederic Weisbecker Architecture doesn't only execute the irq handler on the irq stack 694cc1f0274SFrederic Weisbecker but also irq_exit(). This way we can process softirqs on this irq 695cc1f0274SFrederic Weisbecker stack instead of switching to a new one when we call __do_softirq() 696cc1f0274SFrederic Weisbecker in the end of an hardirq. 697cc1f0274SFrederic Weisbecker This spares a stack switch and improves cache usage on softirq 698cc1f0274SFrederic Weisbecker processing. 699cc1f0274SFrederic Weisbecker 700235a8f02SKirill A. Shutemovconfig PGTABLE_LEVELS 701235a8f02SKirill A. Shutemov int 702235a8f02SKirill A. Shutemov default 2 703235a8f02SKirill A. Shutemov 7042b68f6caSKees Cookconfig ARCH_HAS_ELF_RANDOMIZE 7052b68f6caSKees Cook bool 7062b68f6caSKees Cook help 7072b68f6caSKees Cook An architecture supports choosing randomized locations for 7082b68f6caSKees Cook stack, mmap, brk, and ET_DYN. Defined functions: 7092b68f6caSKees Cook - arch_mmap_rnd() 710204db6edSKees Cook - arch_randomize_brk() 7112b68f6caSKees Cook 712d07e2259SDaniel Cashmanconfig HAVE_ARCH_MMAP_RND_BITS 713d07e2259SDaniel Cashman bool 714d07e2259SDaniel Cashman help 715d07e2259SDaniel Cashman An arch should select this symbol if it supports setting a variable 716d07e2259SDaniel Cashman number of bits for use in establishing the base address for mmap 717d07e2259SDaniel Cashman allocations, has MMU enabled and provides values for both: 718d07e2259SDaniel Cashman - ARCH_MMAP_RND_BITS_MIN 719d07e2259SDaniel Cashman - ARCH_MMAP_RND_BITS_MAX 720d07e2259SDaniel Cashman 7215f56a5dfSJiri Slabyconfig HAVE_EXIT_THREAD 7225f56a5dfSJiri Slaby bool 7235f56a5dfSJiri Slaby help 7245f56a5dfSJiri Slaby An architecture implements exit_thread. 7255f56a5dfSJiri Slaby 726d07e2259SDaniel Cashmanconfig ARCH_MMAP_RND_BITS_MIN 727d07e2259SDaniel Cashman int 728d07e2259SDaniel Cashman 729d07e2259SDaniel Cashmanconfig ARCH_MMAP_RND_BITS_MAX 730d07e2259SDaniel Cashman int 731d07e2259SDaniel Cashman 732d07e2259SDaniel Cashmanconfig ARCH_MMAP_RND_BITS_DEFAULT 733d07e2259SDaniel Cashman int 734d07e2259SDaniel Cashman 735d07e2259SDaniel Cashmanconfig ARCH_MMAP_RND_BITS 736d07e2259SDaniel Cashman int "Number of bits to use for ASLR of mmap base address" if EXPERT 737d07e2259SDaniel Cashman range ARCH_MMAP_RND_BITS_MIN ARCH_MMAP_RND_BITS_MAX 738d07e2259SDaniel Cashman default ARCH_MMAP_RND_BITS_DEFAULT if ARCH_MMAP_RND_BITS_DEFAULT 739d07e2259SDaniel Cashman default ARCH_MMAP_RND_BITS_MIN 740d07e2259SDaniel Cashman depends on HAVE_ARCH_MMAP_RND_BITS 741d07e2259SDaniel Cashman help 742d07e2259SDaniel Cashman This value can be used to select the number of bits to use to 743d07e2259SDaniel Cashman determine the random offset to the base address of vma regions 744d07e2259SDaniel Cashman resulting from mmap allocations. This value will be bounded 745d07e2259SDaniel Cashman by the architecture's minimum and maximum supported values. 746d07e2259SDaniel Cashman 747d07e2259SDaniel Cashman This value can be changed after boot using the 748d07e2259SDaniel Cashman /proc/sys/vm/mmap_rnd_bits tunable 749d07e2259SDaniel Cashman 750d07e2259SDaniel Cashmanconfig HAVE_ARCH_MMAP_RND_COMPAT_BITS 751d07e2259SDaniel Cashman bool 752d07e2259SDaniel Cashman help 753d07e2259SDaniel Cashman An arch should select this symbol if it supports running applications 754d07e2259SDaniel Cashman in compatibility mode, supports setting a variable number of bits for 755d07e2259SDaniel Cashman use in establishing the base address for mmap allocations, has MMU 756d07e2259SDaniel Cashman enabled and provides values for both: 757d07e2259SDaniel Cashman - ARCH_MMAP_RND_COMPAT_BITS_MIN 758d07e2259SDaniel Cashman - ARCH_MMAP_RND_COMPAT_BITS_MAX 759d07e2259SDaniel Cashman 760d07e2259SDaniel Cashmanconfig ARCH_MMAP_RND_COMPAT_BITS_MIN 761d07e2259SDaniel Cashman int 762d07e2259SDaniel Cashman 763d07e2259SDaniel Cashmanconfig ARCH_MMAP_RND_COMPAT_BITS_MAX 764d07e2259SDaniel Cashman int 765d07e2259SDaniel Cashman 766d07e2259SDaniel Cashmanconfig ARCH_MMAP_RND_COMPAT_BITS_DEFAULT 767d07e2259SDaniel Cashman int 768d07e2259SDaniel Cashman 769d07e2259SDaniel Cashmanconfig ARCH_MMAP_RND_COMPAT_BITS 770d07e2259SDaniel Cashman int "Number of bits to use for ASLR of mmap base address for compatible applications" if EXPERT 771d07e2259SDaniel Cashman range ARCH_MMAP_RND_COMPAT_BITS_MIN ARCH_MMAP_RND_COMPAT_BITS_MAX 772d07e2259SDaniel Cashman default ARCH_MMAP_RND_COMPAT_BITS_DEFAULT if ARCH_MMAP_RND_COMPAT_BITS_DEFAULT 773d07e2259SDaniel Cashman default ARCH_MMAP_RND_COMPAT_BITS_MIN 774d07e2259SDaniel Cashman depends on HAVE_ARCH_MMAP_RND_COMPAT_BITS 775d07e2259SDaniel Cashman help 776d07e2259SDaniel Cashman This value can be used to select the number of bits to use to 777d07e2259SDaniel Cashman determine the random offset to the base address of vma regions 778d07e2259SDaniel Cashman resulting from mmap allocations for compatible applications This 779d07e2259SDaniel Cashman value will be bounded by the architecture's minimum and maximum 780d07e2259SDaniel Cashman supported values. 781d07e2259SDaniel Cashman 782d07e2259SDaniel Cashman This value can be changed after boot using the 783d07e2259SDaniel Cashman /proc/sys/vm/mmap_rnd_compat_bits tunable 784d07e2259SDaniel Cashman 7851b028f78SDmitry Safonovconfig HAVE_ARCH_COMPAT_MMAP_BASES 7861b028f78SDmitry Safonov bool 7871b028f78SDmitry Safonov help 7881b028f78SDmitry Safonov This allows 64bit applications to invoke 32-bit mmap() syscall 7891b028f78SDmitry Safonov and vice-versa 32-bit applications to call 64-bit mmap(). 7901b028f78SDmitry Safonov Required for applications doing different bitness syscalls. 7911b028f78SDmitry Safonov 7923033f14aSJosh Triplettconfig HAVE_COPY_THREAD_TLS 7933033f14aSJosh Triplett bool 7943033f14aSJosh Triplett help 7953033f14aSJosh Triplett Architecture provides copy_thread_tls to accept tls argument via 7963033f14aSJosh Triplett normal C parameter passing, rather than extracting the syscall 7973033f14aSJosh Triplett argument from pt_regs. 7983033f14aSJosh Triplett 799b9ab5ebbSJosh Poimboeufconfig HAVE_STACK_VALIDATION 800b9ab5ebbSJosh Poimboeuf bool 801b9ab5ebbSJosh Poimboeuf help 802b9ab5ebbSJosh Poimboeuf Architecture supports the 'objtool check' host tool command, which 803b9ab5ebbSJosh Poimboeuf performs compile-time stack metadata validation. 804b9ab5ebbSJosh Poimboeuf 805af085d90SJosh Poimboeufconfig HAVE_RELIABLE_STACKTRACE 806af085d90SJosh Poimboeuf bool 807af085d90SJosh Poimboeuf help 808af085d90SJosh Poimboeuf Architecture has a save_stack_trace_tsk_reliable() function which 809af085d90SJosh Poimboeuf only returns a stack trace if it can guarantee the trace is reliable. 810af085d90SJosh Poimboeuf 811468a9428SGeorge Spelvinconfig HAVE_ARCH_HASH 812468a9428SGeorge Spelvin bool 813468a9428SGeorge Spelvin default n 814468a9428SGeorge Spelvin help 815468a9428SGeorge Spelvin If this is set, the architecture provides an <asm/hash.h> 816468a9428SGeorge Spelvin file which provides platform-specific implementations of some 817468a9428SGeorge Spelvin functions in <linux/hash.h> or fs/namei.c. 818468a9428SGeorge Spelvin 8193a495511SWilliam Breathitt Grayconfig ISA_BUS_API 8203a495511SWilliam Breathitt Gray def_bool ISA 8213a495511SWilliam Breathitt Gray 822d2125043SAl Viro# 823d2125043SAl Viro# ABI hall of shame 824d2125043SAl Viro# 825d2125043SAl Viroconfig CLONE_BACKWARDS 826d2125043SAl Viro bool 827d2125043SAl Viro help 828d2125043SAl Viro Architecture has tls passed as the 4th argument of clone(2), 829d2125043SAl Viro not the 5th one. 830d2125043SAl Viro 831d2125043SAl Viroconfig CLONE_BACKWARDS2 832d2125043SAl Viro bool 833d2125043SAl Viro help 834d2125043SAl Viro Architecture has the first two arguments of clone(2) swapped. 835d2125043SAl Viro 836dfa9771aSMichal Simekconfig CLONE_BACKWARDS3 837dfa9771aSMichal Simek bool 838dfa9771aSMichal Simek help 839dfa9771aSMichal Simek Architecture has tls passed as the 3rd argument of clone(2), 840dfa9771aSMichal Simek not the 5th one. 841dfa9771aSMichal Simek 842eaca6eaeSAl Viroconfig ODD_RT_SIGACTION 843eaca6eaeSAl Viro bool 844eaca6eaeSAl Viro help 845eaca6eaeSAl Viro Architecture has unusual rt_sigaction(2) arguments 846eaca6eaeSAl Viro 8470a0e8cdfSAl Viroconfig OLD_SIGSUSPEND 8480a0e8cdfSAl Viro bool 8490a0e8cdfSAl Viro help 8500a0e8cdfSAl Viro Architecture has old sigsuspend(2) syscall, of one-argument variety 8510a0e8cdfSAl Viro 8520a0e8cdfSAl Viroconfig OLD_SIGSUSPEND3 8530a0e8cdfSAl Viro bool 8540a0e8cdfSAl Viro help 8550a0e8cdfSAl Viro Even weirder antique ABI - three-argument sigsuspend(2) 8560a0e8cdfSAl Viro 857495dfbf7SAl Viroconfig OLD_SIGACTION 858495dfbf7SAl Viro bool 859495dfbf7SAl Viro help 860495dfbf7SAl Viro Architecture has old sigaction(2) syscall. Nope, not the same 861495dfbf7SAl Viro as OLD_SIGSUSPEND | OLD_SIGSUSPEND3 - alpha has sigsuspend(2), 862495dfbf7SAl Viro but fairly different variant of sigaction(2), thanks to OSF/1 863495dfbf7SAl Viro compatibility... 864495dfbf7SAl Viro 865495dfbf7SAl Viroconfig COMPAT_OLD_SIGACTION 866495dfbf7SAl Viro bool 867495dfbf7SAl Viro 868d4703ddaSDeepa Dinamaniconfig 64BIT_TIME 869d4703ddaSDeepa Dinamani def_bool ARCH_HAS_64BIT_TIME 870d4703ddaSDeepa Dinamani help 871d4703ddaSDeepa Dinamani This should be selected by all architectures that need to support 872d4703ddaSDeepa Dinamani new system calls with a 64-bit time_t. This is relevant on all 32-bit 873d4703ddaSDeepa Dinamani architectures, and 64-bit architectures as part of compat syscall 874d4703ddaSDeepa Dinamani handling. 875d4703ddaSDeepa Dinamani 87617435e5fSDeepa Dinamaniconfig COMPAT_32BIT_TIME 87717435e5fSDeepa Dinamani def_bool (!64BIT && 64BIT_TIME) || COMPAT 87817435e5fSDeepa Dinamani help 87917435e5fSDeepa Dinamani This enables 32 bit time_t support in addition to 64 bit time_t support. 88017435e5fSDeepa Dinamani This is relevant on all 32-bit architectures, and 64-bit architectures 88117435e5fSDeepa Dinamani as part of compat syscall handling. 88217435e5fSDeepa Dinamani 8830d4a619bSChristoph Hellwigconfig ARCH_NO_COHERENT_DMA_MMAP 8840d4a619bSChristoph Hellwig bool 8850d4a619bSChristoph Hellwig 88687a4c375SChristoph Hellwigconfig ARCH_NO_PREEMPT 88787a4c375SChristoph Hellwig bool 88887a4c375SChristoph Hellwig 889fff7fb0bSZhaoxiu Zengconfig CPU_NO_EFFICIENT_FFS 890fff7fb0bSZhaoxiu Zeng def_bool n 891fff7fb0bSZhaoxiu Zeng 892ba14a194SAndy Lutomirskiconfig HAVE_ARCH_VMAP_STACK 893ba14a194SAndy Lutomirski def_bool n 894ba14a194SAndy Lutomirski help 895ba14a194SAndy Lutomirski An arch should select this symbol if it can support kernel stacks 896ba14a194SAndy Lutomirski in vmalloc space. This means: 897ba14a194SAndy Lutomirski 898ba14a194SAndy Lutomirski - vmalloc space must be large enough to hold many kernel stacks. 899ba14a194SAndy Lutomirski This may rule out many 32-bit architectures. 900ba14a194SAndy Lutomirski 901ba14a194SAndy Lutomirski - Stacks in vmalloc space need to work reliably. For example, if 902ba14a194SAndy Lutomirski vmap page tables are created on demand, either this mechanism 903ba14a194SAndy Lutomirski needs to work while the stack points to a virtual address with 904ba14a194SAndy Lutomirski unpopulated page tables or arch code (switch_to() and switch_mm(), 905ba14a194SAndy Lutomirski most likely) needs to ensure that the stack's page table entries 906ba14a194SAndy Lutomirski are populated before running on a possibly unpopulated stack. 907ba14a194SAndy Lutomirski 908ba14a194SAndy Lutomirski - If the stack overflows into a guard page, something reasonable 909ba14a194SAndy Lutomirski should happen. The definition of "reasonable" is flexible, but 910ba14a194SAndy Lutomirski instantly rebooting without logging anything would be unfriendly. 911ba14a194SAndy Lutomirski 912ba14a194SAndy Lutomirskiconfig VMAP_STACK 913ba14a194SAndy Lutomirski default y 914ba14a194SAndy Lutomirski bool "Use a virtually-mapped stack" 915ba14a194SAndy Lutomirski depends on HAVE_ARCH_VMAP_STACK && !KASAN 916ba14a194SAndy Lutomirski ---help--- 917ba14a194SAndy Lutomirski Enable this if you want the use virtually-mapped kernel stacks 918ba14a194SAndy Lutomirski with guard pages. This causes kernel stack overflows to be 919ba14a194SAndy Lutomirski caught immediately rather than causing difficult-to-diagnose 920ba14a194SAndy Lutomirski corruption. 921ba14a194SAndy Lutomirski 922ba14a194SAndy Lutomirski This is presently incompatible with KASAN because KASAN expects 923ba14a194SAndy Lutomirski the stack to map directly to the KASAN shadow map using a formula 924ba14a194SAndy Lutomirski that is incorrect if the stack is in vmalloc space. 925ba14a194SAndy Lutomirski 926ad21fc4fSLaura Abbottconfig ARCH_OPTIONAL_KERNEL_RWX 927ad21fc4fSLaura Abbott def_bool n 928ad21fc4fSLaura Abbott 929ad21fc4fSLaura Abbottconfig ARCH_OPTIONAL_KERNEL_RWX_DEFAULT 930ad21fc4fSLaura Abbott def_bool n 931ad21fc4fSLaura Abbott 932ad21fc4fSLaura Abbottconfig ARCH_HAS_STRICT_KERNEL_RWX 933ad21fc4fSLaura Abbott def_bool n 934ad21fc4fSLaura Abbott 9350f5bf6d0SLaura Abbottconfig STRICT_KERNEL_RWX 936ad21fc4fSLaura Abbott bool "Make kernel text and rodata read-only" if ARCH_OPTIONAL_KERNEL_RWX 937ad21fc4fSLaura Abbott depends on ARCH_HAS_STRICT_KERNEL_RWX 938ad21fc4fSLaura Abbott default !ARCH_OPTIONAL_KERNEL_RWX || ARCH_OPTIONAL_KERNEL_RWX_DEFAULT 939ad21fc4fSLaura Abbott help 940ad21fc4fSLaura Abbott If this is set, kernel text and rodata memory will be made read-only, 941ad21fc4fSLaura Abbott and non-text memory will be made non-executable. This provides 942ad21fc4fSLaura Abbott protection against certain security exploits (e.g. executing the heap 943ad21fc4fSLaura Abbott or modifying text) 944ad21fc4fSLaura Abbott 945ad21fc4fSLaura Abbott These features are considered standard security practice these days. 946ad21fc4fSLaura Abbott You should say Y here in almost all cases. 947ad21fc4fSLaura Abbott 948ad21fc4fSLaura Abbottconfig ARCH_HAS_STRICT_MODULE_RWX 949ad21fc4fSLaura Abbott def_bool n 950ad21fc4fSLaura Abbott 9510f5bf6d0SLaura Abbottconfig STRICT_MODULE_RWX 952ad21fc4fSLaura Abbott bool "Set loadable kernel module data as NX and text as RO" if ARCH_OPTIONAL_KERNEL_RWX 953ad21fc4fSLaura Abbott depends on ARCH_HAS_STRICT_MODULE_RWX && MODULES 954ad21fc4fSLaura Abbott default !ARCH_OPTIONAL_KERNEL_RWX || ARCH_OPTIONAL_KERNEL_RWX_DEFAULT 955ad21fc4fSLaura Abbott help 956ad21fc4fSLaura Abbott If this is set, module text and rodata memory will be made read-only, 957ad21fc4fSLaura Abbott and non-text memory will be made non-executable. This provides 958ad21fc4fSLaura Abbott protection against certain security exploits (e.g. writing to text) 959ad21fc4fSLaura Abbott 960ea8c64acSChristoph Hellwig# select if the architecture provides an asm/dma-direct.h header 961ea8c64acSChristoph Hellwigconfig ARCH_HAS_PHYS_TO_DMA 962ea8c64acSChristoph Hellwig bool 963ea8c64acSChristoph Hellwig 9647a46ec0eSKees Cookconfig ARCH_HAS_REFCOUNT 9657a46ec0eSKees Cook bool 9667a46ec0eSKees Cook help 9677a46ec0eSKees Cook An architecture selects this when it has implemented refcount_t 9687a46ec0eSKees Cook using open coded assembly primitives that provide an optimized 9697a46ec0eSKees Cook refcount_t implementation, possibly at the expense of some full 9707a46ec0eSKees Cook refcount state checks of CONFIG_REFCOUNT_FULL=y. 9717a46ec0eSKees Cook 9727a46ec0eSKees Cook The refcount overflow check behavior, however, must be retained. 9737a46ec0eSKees Cook Catching overflows is the primary security concern for protecting 9747a46ec0eSKees Cook against bugs in reference counts. 9757a46ec0eSKees Cook 976fd25d19fSKees Cookconfig REFCOUNT_FULL 977fd25d19fSKees Cook bool "Perform full reference count validation at the expense of speed" 978fd25d19fSKees Cook help 979fd25d19fSKees Cook Enabling this switches the refcounting infrastructure from a fast 980fd25d19fSKees Cook unchecked atomic_t implementation to a fully state checked 981fd25d19fSKees Cook implementation, which can be (slightly) slower but provides protections 982fd25d19fSKees Cook against various use-after-free conditions that can be used in 983fd25d19fSKees Cook security flaw exploits. 984fd25d19fSKees Cook 9852521f2c2SPeter Oberparleitersource "kernel/gcov/Kconfig" 98622471e13SRandy Dunlap 98722471e13SRandy Dunlapendmenu 988