1b2441318SGreg Kroah-Hartman# SPDX-License-Identifier: GPL-2.0 2fb32e03fSMathieu Desnoyers# 3fb32e03fSMathieu Desnoyers# General architecture dependent options 4fb32e03fSMathieu Desnoyers# 5125e5645SMathieu Desnoyers 6692f66f2SHari Bathiniconfig CRASH_CORE 7692f66f2SHari Bathini bool 8692f66f2SHari Bathini 92965faa5SDave Youngconfig KEXEC_CORE 10692f66f2SHari Bathini select CRASH_CORE 112965faa5SDave Young bool 122965faa5SDave Young 13467d2782SThiago Jung Bauermannconfig HAVE_IMA_KEXEC 14467d2782SThiago Jung Bauermann bool 15467d2782SThiago Jung Bauermann 16125e5645SMathieu Desnoyersconfig OPROFILE 17b309a294SRobert Richter tristate "OProfile system profiling" 18125e5645SMathieu Desnoyers depends on PROFILING 19125e5645SMathieu Desnoyers depends on HAVE_OPROFILE 20d69d59f4SIngo Molnar select RING_BUFFER 219a5963ebSChristian Borntraeger select RING_BUFFER_ALLOW_SWAP 22125e5645SMathieu Desnoyers help 23125e5645SMathieu Desnoyers OProfile is a profiling system capable of profiling the 24125e5645SMathieu Desnoyers whole system, include the kernel, kernel modules, libraries, 25125e5645SMathieu Desnoyers and applications. 26125e5645SMathieu Desnoyers 27125e5645SMathieu Desnoyers If unsure, say N. 28125e5645SMathieu Desnoyers 294d4036e0SJason Yehconfig OPROFILE_EVENT_MULTIPLEX 304d4036e0SJason Yeh bool "OProfile multiplexing support (EXPERIMENTAL)" 314d4036e0SJason Yeh default n 324d4036e0SJason Yeh depends on OPROFILE && X86 334d4036e0SJason Yeh help 344d4036e0SJason Yeh The number of hardware counters is limited. The multiplexing 354d4036e0SJason Yeh feature enables OProfile to gather more events than counters 364d4036e0SJason Yeh are provided by the hardware. This is realized by switching 379332ef9dSMasahiro Yamada between events at a user specified time interval. 384d4036e0SJason Yeh 394d4036e0SJason Yeh If unsure, say N. 404d4036e0SJason Yeh 41125e5645SMathieu Desnoyersconfig HAVE_OPROFILE 429ba16087SJan Beulich bool 43125e5645SMathieu Desnoyers 44dcfce4a0SRobert Richterconfig OPROFILE_NMI_TIMER 45dcfce4a0SRobert Richter def_bool y 46af9feebeSAnton Blanchard depends on PERF_EVENTS && HAVE_PERF_EVENTS_NMI && !PPC64 47dcfce4a0SRobert Richter 48125e5645SMathieu Desnoyersconfig KPROBES 49125e5645SMathieu Desnoyers bool "Kprobes" 5005ed160eSMasami Hiramatsu depends on MODULES 51125e5645SMathieu Desnoyers depends on HAVE_KPROBES 5205ed160eSMasami Hiramatsu select KALLSYMS 53125e5645SMathieu Desnoyers help 54125e5645SMathieu Desnoyers Kprobes allows you to trap at almost any kernel address and 55125e5645SMathieu Desnoyers execute a callback function. register_kprobe() establishes 56125e5645SMathieu Desnoyers a probepoint and specifies the callback. Kprobes is useful 57125e5645SMathieu Desnoyers for kernel debugging, non-intrusive instrumentation and testing. 58125e5645SMathieu Desnoyers If in doubt, say "N". 59125e5645SMathieu Desnoyers 6045f81b1cSSteven Rostedtconfig JUMP_LABEL 61c5905afbSIngo Molnar bool "Optimize very unlikely/likely branches" 6245f81b1cSSteven Rostedt depends on HAVE_ARCH_JUMP_LABEL 6345f81b1cSSteven Rostedt help 64c5905afbSIngo Molnar This option enables a transparent branch optimization that 65c5905afbSIngo Molnar makes certain almost-always-true or almost-always-false branch 66c5905afbSIngo Molnar conditions even cheaper to execute within the kernel. 6745f81b1cSSteven Rostedt 68c5905afbSIngo Molnar Certain performance-sensitive kernel code, such as trace points, 69c5905afbSIngo Molnar scheduler functionality, networking code and KVM have such 70c5905afbSIngo Molnar branches and include support for this optimization technique. 71c5905afbSIngo Molnar 72c5905afbSIngo Molnar If it is detected that the compiler has support for "asm goto", 73c5905afbSIngo Molnar the kernel will compile such branches with just a nop 74c5905afbSIngo Molnar instruction. When the condition flag is toggled to true, the 75c5905afbSIngo Molnar nop will be converted to a jump instruction to execute the 76c5905afbSIngo Molnar conditional block of instructions. 77c5905afbSIngo Molnar 78c5905afbSIngo Molnar This technique lowers overhead and stress on the branch prediction 79c5905afbSIngo Molnar of the processor and generally makes the kernel faster. The update 80c5905afbSIngo Molnar of the condition is slower, but those are always very rare. 81c5905afbSIngo Molnar 82c5905afbSIngo Molnar ( On 32-bit x86, the necessary options added to the compiler 83c5905afbSIngo Molnar flags may increase the size of the kernel slightly. ) 8445f81b1cSSteven Rostedt 851987c947SPeter Zijlstraconfig STATIC_KEYS_SELFTEST 861987c947SPeter Zijlstra bool "Static key selftest" 871987c947SPeter Zijlstra depends on JUMP_LABEL 881987c947SPeter Zijlstra help 891987c947SPeter Zijlstra Boot time self-test of the branch patching code. 901987c947SPeter Zijlstra 91afd66255SMasami Hiramatsuconfig OPTPROBES 925cc718b9SMasami Hiramatsu def_bool y 935cc718b9SMasami Hiramatsu depends on KPROBES && HAVE_OPTPROBES 94a30b85dfSMasami Hiramatsu select TASKS_RCU if PREEMPT 95afd66255SMasami Hiramatsu 96e7dbfe34SMasami Hiramatsuconfig KPROBES_ON_FTRACE 97e7dbfe34SMasami Hiramatsu def_bool y 98e7dbfe34SMasami Hiramatsu depends on KPROBES && HAVE_KPROBES_ON_FTRACE 99e7dbfe34SMasami Hiramatsu depends on DYNAMIC_FTRACE_WITH_REGS 100e7dbfe34SMasami Hiramatsu help 101e7dbfe34SMasami Hiramatsu If function tracer is enabled and the arch supports full 102e7dbfe34SMasami Hiramatsu passing of pt_regs to function tracing, then kprobes can 103e7dbfe34SMasami Hiramatsu optimize on top of function tracing. 104e7dbfe34SMasami Hiramatsu 1052b144498SSrikar Dronamrajuconfig UPROBES 10609294e31SDavid A. Long def_bool n 107e8f4aa60SAllen Pais depends on ARCH_SUPPORTS_UPROBES 1082b144498SSrikar Dronamraju help 1097b2d81d4SIngo Molnar Uprobes is the user-space counterpart to kprobes: they 1107b2d81d4SIngo Molnar enable instrumentation applications (such as 'perf probe') 1117b2d81d4SIngo Molnar to establish unintrusive probes in user-space binaries and 1127b2d81d4SIngo Molnar libraries, by executing handler functions when the probes 1137b2d81d4SIngo Molnar are hit by user-space applications. 1147b2d81d4SIngo Molnar 1157b2d81d4SIngo Molnar ( These probes come in the form of single-byte breakpoints, 1167b2d81d4SIngo Molnar managed by the kernel and kept transparent to the probed 1177b2d81d4SIngo Molnar application. ) 1182b144498SSrikar Dronamraju 119c19fa94aSJames Hoganconfig HAVE_64BIT_ALIGNED_ACCESS 120c19fa94aSJames Hogan def_bool 64BIT && !HAVE_EFFICIENT_UNALIGNED_ACCESS 121c19fa94aSJames Hogan help 122c19fa94aSJames Hogan Some architectures require 64 bit accesses to be 64 bit 123c19fa94aSJames Hogan aligned, which also requires structs containing 64 bit values 124c19fa94aSJames Hogan to be 64 bit aligned too. This includes some 32 bit 125c19fa94aSJames Hogan architectures which can do 64 bit accesses, as well as 64 bit 126c19fa94aSJames Hogan architectures without unaligned access. 127c19fa94aSJames Hogan 128c19fa94aSJames Hogan This symbol should be selected by an architecture if 64 bit 129c19fa94aSJames Hogan accesses are required to be 64 bit aligned in this way even 130c19fa94aSJames Hogan though it is not a 64 bit architecture. 131c19fa94aSJames Hogan 132c19fa94aSJames Hogan See Documentation/unaligned-memory-access.txt for more 133c19fa94aSJames Hogan information on the topic of unaligned memory accesses. 134c19fa94aSJames Hogan 13558340a07SJohannes Bergconfig HAVE_EFFICIENT_UNALIGNED_ACCESS 1369ba16087SJan Beulich bool 13758340a07SJohannes Berg help 13858340a07SJohannes Berg Some architectures are unable to perform unaligned accesses 13958340a07SJohannes Berg without the use of get_unaligned/put_unaligned. Others are 14058340a07SJohannes Berg unable to perform such accesses efficiently (e.g. trap on 14158340a07SJohannes Berg unaligned access and require fixing it up in the exception 14258340a07SJohannes Berg handler.) 14358340a07SJohannes Berg 14458340a07SJohannes Berg This symbol should be selected by an architecture if it can 14558340a07SJohannes Berg perform unaligned accesses efficiently to allow different 14658340a07SJohannes Berg code paths to be selected for these cases. Some network 14758340a07SJohannes Berg drivers, for example, could opt to not fix up alignment 14858340a07SJohannes Berg problems with received packets if doing so would not help 14958340a07SJohannes Berg much. 15058340a07SJohannes Berg 15158340a07SJohannes Berg See Documentation/unaligned-memory-access.txt for more 15258340a07SJohannes Berg information on the topic of unaligned memory accesses. 15358340a07SJohannes Berg 154cf66bb93SDavid Woodhouseconfig ARCH_USE_BUILTIN_BSWAP 155cf66bb93SDavid Woodhouse bool 156cf66bb93SDavid Woodhouse help 157cf66bb93SDavid Woodhouse Modern versions of GCC (since 4.4) have builtin functions 158cf66bb93SDavid Woodhouse for handling byte-swapping. Using these, instead of the old 159cf66bb93SDavid Woodhouse inline assembler that the architecture code provides in the 160cf66bb93SDavid Woodhouse __arch_bswapXX() macros, allows the compiler to see what's 161cf66bb93SDavid Woodhouse happening and offers more opportunity for optimisation. In 162cf66bb93SDavid Woodhouse particular, the compiler will be able to combine the byteswap 163cf66bb93SDavid Woodhouse with a nearby load or store and use load-and-swap or 164cf66bb93SDavid Woodhouse store-and-swap instructions if the architecture has them. It 165cf66bb93SDavid Woodhouse should almost *never* result in code which is worse than the 166cf66bb93SDavid Woodhouse hand-coded assembler in <asm/swab.h>. But just in case it 167cf66bb93SDavid Woodhouse does, the use of the builtins is optional. 168cf66bb93SDavid Woodhouse 169cf66bb93SDavid Woodhouse Any architecture with load-and-swap or store-and-swap 170cf66bb93SDavid Woodhouse instructions should set this. And it shouldn't hurt to set it 171cf66bb93SDavid Woodhouse on architectures that don't have such instructions. 172cf66bb93SDavid Woodhouse 1739edddaa2SAnanth N Mavinakayanahalliconfig KRETPROBES 1749edddaa2SAnanth N Mavinakayanahalli def_bool y 1759edddaa2SAnanth N Mavinakayanahalli depends on KPROBES && HAVE_KRETPROBES 1769edddaa2SAnanth N Mavinakayanahalli 1777c68af6eSAvi Kivityconfig USER_RETURN_NOTIFIER 1787c68af6eSAvi Kivity bool 1797c68af6eSAvi Kivity depends on HAVE_USER_RETURN_NOTIFIER 1807c68af6eSAvi Kivity help 1817c68af6eSAvi Kivity Provide a kernel-internal notification when a cpu is about to 1827c68af6eSAvi Kivity switch to user mode. 1837c68af6eSAvi Kivity 18428b2ee20SRik van Rielconfig HAVE_IOREMAP_PROT 1859ba16087SJan Beulich bool 18628b2ee20SRik van Riel 187125e5645SMathieu Desnoyersconfig HAVE_KPROBES 1889ba16087SJan Beulich bool 1899edddaa2SAnanth N Mavinakayanahalli 1909edddaa2SAnanth N Mavinakayanahalliconfig HAVE_KRETPROBES 1919ba16087SJan Beulich bool 19274bc7ceeSArthur Kepner 193afd66255SMasami Hiramatsuconfig HAVE_OPTPROBES 194afd66255SMasami Hiramatsu bool 195d314d74cSCong Wang 196e7dbfe34SMasami Hiramatsuconfig HAVE_KPROBES_ON_FTRACE 197e7dbfe34SMasami Hiramatsu bool 198e7dbfe34SMasami Hiramatsu 199540adea3SMasami Hiramatsuconfig HAVE_FUNCTION_ERROR_INJECTION 2009802d865SJosef Bacik bool 2019802d865SJosef Bacik 20242a0bb3fSPetr Mladekconfig HAVE_NMI 20342a0bb3fSPetr Mladek bool 20442a0bb3fSPetr Mladek 2051f5a4ad9SRoland McGrath# 2061f5a4ad9SRoland McGrath# An arch should select this if it provides all these things: 2071f5a4ad9SRoland McGrath# 2081f5a4ad9SRoland McGrath# task_pt_regs() in asm/processor.h or asm/ptrace.h 2091f5a4ad9SRoland McGrath# arch_has_single_step() if there is hardware single-step support 2101f5a4ad9SRoland McGrath# arch_has_block_step() if there is hardware block-step support 2111f5a4ad9SRoland McGrath# asm/syscall.h supplying asm-generic/syscall.h interface 2121f5a4ad9SRoland McGrath# linux/regset.h user_regset interfaces 2131f5a4ad9SRoland McGrath# CORE_DUMP_USE_REGSET #define'd in linux/elf.h 2141f5a4ad9SRoland McGrath# TIF_SYSCALL_TRACE calls tracehook_report_syscall_{entry,exit} 2151f5a4ad9SRoland McGrath# TIF_NOTIFY_RESUME calls tracehook_notify_resume() 2161f5a4ad9SRoland McGrath# signal delivery calls tracehook_signal_handler() 2171f5a4ad9SRoland McGrath# 2181f5a4ad9SRoland McGrathconfig HAVE_ARCH_TRACEHOOK 2199ba16087SJan Beulich bool 2201f5a4ad9SRoland McGrath 221c64be2bbSMarek Szyprowskiconfig HAVE_DMA_CONTIGUOUS 222c64be2bbSMarek Szyprowski bool 223c64be2bbSMarek Szyprowski 22429d5e047SThomas Gleixnerconfig GENERIC_SMP_IDLE_THREAD 22529d5e047SThomas Gleixner bool 22629d5e047SThomas Gleixner 227485cf5daSKevin Hilmanconfig GENERIC_IDLE_POLL_SETUP 228485cf5daSKevin Hilman bool 229485cf5daSKevin Hilman 2306974f0c4SDaniel Micayconfig ARCH_HAS_FORTIFY_SOURCE 2316974f0c4SDaniel Micay bool 2326974f0c4SDaniel Micay help 2336974f0c4SDaniel Micay An architecture should select this when it can successfully 2346974f0c4SDaniel Micay build and run with CONFIG_FORTIFY_SOURCE. 2356974f0c4SDaniel Micay 236d2852a22SDaniel Borkmann# Select if arch has all set_memory_ro/rw/x/nx() functions in asm/cacheflush.h 237d2852a22SDaniel Borkmannconfig ARCH_HAS_SET_MEMORY 238d2852a22SDaniel Borkmann bool 239d2852a22SDaniel Borkmann 2400500871fSDavid Howells# Select if arch init_task must go in the __init_task_data section 2410500871fSDavid Howellsconfig ARCH_TASK_STRUCT_ON_STACK 242a4a2eb49SThomas Gleixner bool 243a4a2eb49SThomas Gleixner 244f5e10287SThomas Gleixner# Select if arch has its private alloc_task_struct() function 245f5e10287SThomas Gleixnerconfig ARCH_TASK_STRUCT_ALLOCATOR 246f5e10287SThomas Gleixner bool 247f5e10287SThomas Gleixner 2485905429aSKees Cookconfig HAVE_ARCH_THREAD_STRUCT_WHITELIST 2495905429aSKees Cook bool 2505905429aSKees Cook depends on !ARCH_TASK_STRUCT_ALLOCATOR 2515905429aSKees Cook help 2525905429aSKees Cook An architecture should select this to provide hardened usercopy 2535905429aSKees Cook knowledge about what region of the thread_struct should be 2545905429aSKees Cook whitelisted for copying to userspace. Normally this is only the 2555905429aSKees Cook FPU registers. Specifically, arch_thread_struct_whitelist() 2565905429aSKees Cook should be implemented. Without this, the entire thread_struct 2575905429aSKees Cook field in task_struct will be left whitelisted. 2585905429aSKees Cook 259b235beeaSLinus Torvalds# Select if arch has its private alloc_thread_stack() function 260b235beeaSLinus Torvaldsconfig ARCH_THREAD_STACK_ALLOCATOR 261f5e10287SThomas Gleixner bool 262f5e10287SThomas Gleixner 2635aaeb5c0SIngo Molnar# Select if arch wants to size task_struct dynamically via arch_task_struct_size: 2645aaeb5c0SIngo Molnarconfig ARCH_WANTS_DYNAMIC_TASK_STRUCT 2655aaeb5c0SIngo Molnar bool 2665aaeb5c0SIngo Molnar 267f850c30cSHeiko Carstensconfig HAVE_REGS_AND_STACK_ACCESS_API 268f850c30cSHeiko Carstens bool 269e01292b1SHeiko Carstens help 270e01292b1SHeiko Carstens This symbol should be selected by an architecure if it supports 271e01292b1SHeiko Carstens the API needed to access registers and stack entries from pt_regs, 272e01292b1SHeiko Carstens declared in asm/ptrace.h 273e01292b1SHeiko Carstens For example the kprobes-based event tracer needs this API. 274f850c30cSHeiko Carstens 275d7822b1eSMathieu Desnoyersconfig HAVE_RSEQ 276d7822b1eSMathieu Desnoyers bool 277d7822b1eSMathieu Desnoyers depends on HAVE_REGS_AND_STACK_ACCESS_API 278d7822b1eSMathieu Desnoyers help 279d7822b1eSMathieu Desnoyers This symbol should be selected by an architecture if it 280d7822b1eSMathieu Desnoyers supports an implementation of restartable sequences. 281d7822b1eSMathieu Desnoyers 2829483a578SDavid Brownellconfig HAVE_CLK 2839ba16087SJan Beulich bool 2849483a578SDavid Brownell help 2859483a578SDavid Brownell The <linux/clk.h> calls support software clock gating and 2869483a578SDavid Brownell thus are a key power management tool on many systems. 2879483a578SDavid Brownell 28862a038d3SK.Prasadconfig HAVE_HW_BREAKPOINT 28962a038d3SK.Prasad bool 29099e8c5a3SFrederic Weisbecker depends on PERF_EVENTS 29162a038d3SK.Prasad 2920102752eSFrederic Weisbeckerconfig HAVE_MIXED_BREAKPOINTS_REGS 2930102752eSFrederic Weisbecker bool 2940102752eSFrederic Weisbecker depends on HAVE_HW_BREAKPOINT 2950102752eSFrederic Weisbecker help 2960102752eSFrederic Weisbecker Depending on the arch implementation of hardware breakpoints, 2970102752eSFrederic Weisbecker some of them have separate registers for data and instruction 2980102752eSFrederic Weisbecker breakpoints addresses, others have mixed registers to store 2990102752eSFrederic Weisbecker them but define the access type in a control register. 3000102752eSFrederic Weisbecker Select this option if your arch implements breakpoints under the 3010102752eSFrederic Weisbecker latter fashion. 3020102752eSFrederic Weisbecker 3037c68af6eSAvi Kivityconfig HAVE_USER_RETURN_NOTIFIER 3047c68af6eSAvi Kivity bool 305a1922ed6SIngo Molnar 306c01d4323SFrederic Weisbeckerconfig HAVE_PERF_EVENTS_NMI 307c01d4323SFrederic Weisbecker bool 30823637d47SFrederic Weisbecker help 30923637d47SFrederic Weisbecker System hardware can generate an NMI using the perf event 31023637d47SFrederic Weisbecker subsystem. Also has support for calculating CPU cycle events 31123637d47SFrederic Weisbecker to determine how many clock cycles in a given period. 312c01d4323SFrederic Weisbecker 31305a4a952SNicholas Pigginconfig HAVE_HARDLOCKUP_DETECTOR_PERF 31405a4a952SNicholas Piggin bool 31505a4a952SNicholas Piggin depends on HAVE_PERF_EVENTS_NMI 31605a4a952SNicholas Piggin help 31705a4a952SNicholas Piggin The arch chooses to use the generic perf-NMI-based hardlockup 31805a4a952SNicholas Piggin detector. Must define HAVE_PERF_EVENTS_NMI. 31905a4a952SNicholas Piggin 32005a4a952SNicholas Pigginconfig HAVE_NMI_WATCHDOG 32105a4a952SNicholas Piggin depends on HAVE_NMI 32205a4a952SNicholas Piggin bool 32305a4a952SNicholas Piggin help 32405a4a952SNicholas Piggin The arch provides a low level NMI watchdog. It provides 32505a4a952SNicholas Piggin asm/nmi.h, and defines its own arch_touch_nmi_watchdog(). 32605a4a952SNicholas Piggin 32705a4a952SNicholas Pigginconfig HAVE_HARDLOCKUP_DETECTOR_ARCH 32805a4a952SNicholas Piggin bool 32905a4a952SNicholas Piggin select HAVE_NMI_WATCHDOG 33005a4a952SNicholas Piggin help 33105a4a952SNicholas Piggin The arch chooses to provide its own hardlockup detector, which is 33205a4a952SNicholas Piggin a superset of the HAVE_NMI_WATCHDOG. It also conforms to config 33305a4a952SNicholas Piggin interfaces and parameters provided by hardlockup detector subsystem. 33405a4a952SNicholas Piggin 335c5e63197SJiri Olsaconfig HAVE_PERF_REGS 336c5e63197SJiri Olsa bool 337c5e63197SJiri Olsa help 338c5e63197SJiri Olsa Support selective register dumps for perf events. This includes 339c5e63197SJiri Olsa bit-mapping of each registers and a unique architecture id. 340c5e63197SJiri Olsa 341c5ebcedbSJiri Olsaconfig HAVE_PERF_USER_STACK_DUMP 342c5ebcedbSJiri Olsa bool 343c5ebcedbSJiri Olsa help 344c5ebcedbSJiri Olsa Support user stack dumps for perf event samples. This needs 345c5ebcedbSJiri Olsa access to the user stack pointer which is not unified across 346c5ebcedbSJiri Olsa architectures. 347c5ebcedbSJiri Olsa 348bf5438fcSJason Baronconfig HAVE_ARCH_JUMP_LABEL 349bf5438fcSJason Baron bool 350bf5438fcSJason Baron 35126723911SPeter Zijlstraconfig HAVE_RCU_TABLE_FREE 35226723911SPeter Zijlstra bool 35326723911SPeter Zijlstra 354df013ffbSHuang Yingconfig ARCH_HAVE_NMI_SAFE_CMPXCHG 355df013ffbSHuang Ying bool 356df013ffbSHuang Ying 35743570fd2SHeiko Carstensconfig HAVE_ALIGNED_STRUCT_PAGE 35843570fd2SHeiko Carstens bool 35943570fd2SHeiko Carstens help 36043570fd2SHeiko Carstens This makes sure that struct pages are double word aligned and that 36143570fd2SHeiko Carstens e.g. the SLUB allocator can perform double word atomic operations 36243570fd2SHeiko Carstens on a struct page for better performance. However selecting this 36343570fd2SHeiko Carstens might increase the size of a struct page by a word. 36443570fd2SHeiko Carstens 3654156153cSHeiko Carstensconfig HAVE_CMPXCHG_LOCAL 3664156153cSHeiko Carstens bool 3674156153cSHeiko Carstens 3682565409fSHeiko Carstensconfig HAVE_CMPXCHG_DOUBLE 3692565409fSHeiko Carstens bool 3702565409fSHeiko Carstens 37177e58496SPaul E. McKenneyconfig ARCH_WEAK_RELEASE_ACQUIRE 37277e58496SPaul E. McKenney bool 37377e58496SPaul E. McKenney 374c1d7e01dSWill Deaconconfig ARCH_WANT_IPC_PARSE_VERSION 375c1d7e01dSWill Deacon bool 376c1d7e01dSWill Deacon 377c1d7e01dSWill Deaconconfig ARCH_WANT_COMPAT_IPC_PARSE_VERSION 378c1d7e01dSWill Deacon bool 379c1d7e01dSWill Deacon 38048b25c43SChris Metcalfconfig ARCH_WANT_OLD_COMPAT_IPC 381c1d7e01dSWill Deacon select ARCH_WANT_COMPAT_IPC_PARSE_VERSION 38248b25c43SChris Metcalf bool 38348b25c43SChris Metcalf 384e2cfabdfSWill Drewryconfig HAVE_ARCH_SECCOMP_FILTER 385e2cfabdfSWill Drewry bool 386e2cfabdfSWill Drewry help 387fb0fadf9SWill Drewry An arch should select this symbol if it provides all of these things: 388bb6ea430SWill Drewry - syscall_get_arch() 389bb6ea430SWill Drewry - syscall_get_arguments() 390bb6ea430SWill Drewry - syscall_rollback() 391bb6ea430SWill Drewry - syscall_set_return_value() 392fb0fadf9SWill Drewry - SIGSYS siginfo_t support 393fb0fadf9SWill Drewry - secure_computing is called from a ptrace_event()-safe context 394fb0fadf9SWill Drewry - secure_computing return value is checked and a return value of -1 395fb0fadf9SWill Drewry results in the system call being skipped immediately. 39648dc92b9SKees Cook - seccomp syscall wired up 397e2cfabdfSWill Drewry 398e2cfabdfSWill Drewryconfig SECCOMP_FILTER 399e2cfabdfSWill Drewry def_bool y 400e2cfabdfSWill Drewry depends on HAVE_ARCH_SECCOMP_FILTER && SECCOMP && NET 401e2cfabdfSWill Drewry help 402e2cfabdfSWill Drewry Enable tasks to build secure computing environments defined 403e2cfabdfSWill Drewry in terms of Berkeley Packet Filter programs which implement 404e2cfabdfSWill Drewry task-defined system call filtering polices. 405e2cfabdfSWill Drewry 4065fb94e9cSMauro Carvalho Chehab See Documentation/userspace-api/seccomp_filter.rst for details. 407e2cfabdfSWill Drewry 408d148eac0SMasahiro Yamadaconfig HAVE_STACKPROTECTOR 40919952a92SKees Cook bool 41019952a92SKees Cook help 41119952a92SKees Cook An arch should select this symbol if: 41219952a92SKees Cook - it has implemented a stack canary (e.g. __stack_chk_guard) 41319952a92SKees Cook 4142a61f474SMasahiro Yamadaconfig CC_HAS_STACKPROTECTOR_NONE 4152a61f474SMasahiro Yamada def_bool $(cc-option,-fno-stack-protector) 4162a61f474SMasahiro Yamada 417050e9baaSLinus Torvaldsconfig STACKPROTECTOR 4182a61f474SMasahiro Yamada bool "Stack Protector buffer overflow detection" 419d148eac0SMasahiro Yamada depends on HAVE_STACKPROTECTOR 4202a61f474SMasahiro Yamada depends on $(cc-option,-fstack-protector) 4212a61f474SMasahiro Yamada default y 4228779657dSKees Cook help 4238779657dSKees Cook This option turns on the "stack-protector" GCC feature. This 42419952a92SKees Cook feature puts, at the beginning of functions, a canary value on 42519952a92SKees Cook the stack just before the return address, and validates 42619952a92SKees Cook the value just before actually returning. Stack based buffer 42719952a92SKees Cook overflows (that need to overwrite this return address) now also 42819952a92SKees Cook overwrite the canary, which gets detected and the attack is then 42919952a92SKees Cook neutralized via a kernel panic. 43019952a92SKees Cook 4318779657dSKees Cook Functions will have the stack-protector canary logic added if they 4328779657dSKees Cook have an 8-byte or larger character array on the stack. 4338779657dSKees Cook 43419952a92SKees Cook This feature requires gcc version 4.2 or above, or a distribution 4358779657dSKees Cook gcc with the feature backported ("-fstack-protector"). 4368779657dSKees Cook 4378779657dSKees Cook On an x86 "defconfig" build, this feature adds canary checks to 4388779657dSKees Cook about 3% of all kernel functions, which increases kernel code size 4398779657dSKees Cook by about 0.3%. 4408779657dSKees Cook 441050e9baaSLinus Torvaldsconfig STACKPROTECTOR_STRONG 4422a61f474SMasahiro Yamada bool "Strong Stack Protector" 443050e9baaSLinus Torvalds depends on STACKPROTECTOR 4442a61f474SMasahiro Yamada depends on $(cc-option,-fstack-protector-strong) 4452a61f474SMasahiro Yamada default y 4468779657dSKees Cook help 4478779657dSKees Cook Functions will have the stack-protector canary logic added in any 4488779657dSKees Cook of the following conditions: 4498779657dSKees Cook 4508779657dSKees Cook - local variable's address used as part of the right hand side of an 4518779657dSKees Cook assignment or function argument 4528779657dSKees Cook - local variable is an array (or union containing an array), 4538779657dSKees Cook regardless of array type or length 4548779657dSKees Cook - uses register local variables 4558779657dSKees Cook 4568779657dSKees Cook This feature requires gcc version 4.9 or above, or a distribution 4578779657dSKees Cook gcc with the feature backported ("-fstack-protector-strong"). 4588779657dSKees Cook 4598779657dSKees Cook On an x86 "defconfig" build, this feature adds canary checks to 4608779657dSKees Cook about 20% of all kernel functions, which increases the kernel code 4618779657dSKees Cook size by about 2%. 4628779657dSKees Cook 4630f60a8efSKees Cookconfig HAVE_ARCH_WITHIN_STACK_FRAMES 4640f60a8efSKees Cook bool 4650f60a8efSKees Cook help 4660f60a8efSKees Cook An architecture should select this if it can walk the kernel stack 4670f60a8efSKees Cook frames to determine if an object is part of either the arguments 4680f60a8efSKees Cook or local variables (i.e. that it excludes saved return addresses, 4690f60a8efSKees Cook and similar) by implementing an inline arch_within_stack_frames(), 4700f60a8efSKees Cook which is used by CONFIG_HARDENED_USERCOPY. 4710f60a8efSKees Cook 47291d1aa43SFrederic Weisbeckerconfig HAVE_CONTEXT_TRACKING 4732b1d5024SFrederic Weisbecker bool 4742b1d5024SFrederic Weisbecker help 47591d1aa43SFrederic Weisbecker Provide kernel/user boundaries probes necessary for subsystems 47691d1aa43SFrederic Weisbecker that need it, such as userspace RCU extended quiescent state. 47791d1aa43SFrederic Weisbecker Syscalls need to be wrapped inside user_exit()-user_enter() through 47891d1aa43SFrederic Weisbecker the slow path using TIF_NOHZ flag. Exceptions handlers must be 47991d1aa43SFrederic Weisbecker wrapped as well. Irqs are already protected inside 48091d1aa43SFrederic Weisbecker rcu_irq_enter/rcu_irq_exit() but preemption or signal handling on 48191d1aa43SFrederic Weisbecker irq exit still need to be protected. 4822b1d5024SFrederic Weisbecker 483b952741cSFrederic Weisbeckerconfig HAVE_VIRT_CPU_ACCOUNTING 484b952741cSFrederic Weisbecker bool 485b952741cSFrederic Weisbecker 48640565b5aSStanislaw Gruszkaconfig ARCH_HAS_SCALED_CPUTIME 48740565b5aSStanislaw Gruszka bool 48840565b5aSStanislaw Gruszka 489554b0004SKevin Hilmanconfig HAVE_VIRT_CPU_ACCOUNTING_GEN 490554b0004SKevin Hilman bool 491554b0004SKevin Hilman default y if 64BIT 492554b0004SKevin Hilman help 493554b0004SKevin Hilman With VIRT_CPU_ACCOUNTING_GEN, cputime_t becomes 64-bit. 494554b0004SKevin Hilman Before enabling this option, arch code must be audited 495554b0004SKevin Hilman to ensure there are no races in concurrent read/write of 496554b0004SKevin Hilman cputime_t. For example, reading/writing 64-bit cputime_t on 497554b0004SKevin Hilman some 32-bit arches may require multiple accesses, so proper 498554b0004SKevin Hilman locking is needed to protect against concurrent accesses. 499554b0004SKevin Hilman 500554b0004SKevin Hilman 501fdf9c356SFrederic Weisbeckerconfig HAVE_IRQ_TIME_ACCOUNTING 502fdf9c356SFrederic Weisbecker bool 503fdf9c356SFrederic Weisbecker help 504fdf9c356SFrederic Weisbecker Archs need to ensure they use a high enough resolution clock to 505fdf9c356SFrederic Weisbecker support irq time accounting and then call enable_sched_clock_irqtime(). 506fdf9c356SFrederic Weisbecker 50715626062SGerald Schaeferconfig HAVE_ARCH_TRANSPARENT_HUGEPAGE 50815626062SGerald Schaefer bool 50915626062SGerald Schaefer 510a00cc7d9SMatthew Wilcoxconfig HAVE_ARCH_TRANSPARENT_HUGEPAGE_PUD 511a00cc7d9SMatthew Wilcox bool 512a00cc7d9SMatthew Wilcox 5130ddab1d2SToshi Kaniconfig HAVE_ARCH_HUGE_VMAP 5140ddab1d2SToshi Kani bool 5150ddab1d2SToshi Kani 5160f8975ecSPavel Emelyanovconfig HAVE_ARCH_SOFT_DIRTY 5170f8975ecSPavel Emelyanov bool 5180f8975ecSPavel Emelyanov 519786d35d4SDavid Howellsconfig HAVE_MOD_ARCH_SPECIFIC 520786d35d4SDavid Howells bool 521786d35d4SDavid Howells help 522786d35d4SDavid Howells The arch uses struct mod_arch_specific to store data. Many arches 523786d35d4SDavid Howells just need a simple module loader without arch specific data - those 524786d35d4SDavid Howells should not enable this. 525786d35d4SDavid Howells 526786d35d4SDavid Howellsconfig MODULES_USE_ELF_RELA 527786d35d4SDavid Howells bool 528786d35d4SDavid Howells help 529786d35d4SDavid Howells Modules only use ELF RELA relocations. Modules with ELF REL 530786d35d4SDavid Howells relocations will give an error. 531786d35d4SDavid Howells 532786d35d4SDavid Howellsconfig MODULES_USE_ELF_REL 533786d35d4SDavid Howells bool 534786d35d4SDavid Howells help 535786d35d4SDavid Howells Modules only use ELF REL relocations. Modules with ELF RELA 536786d35d4SDavid Howells relocations will give an error. 537786d35d4SDavid Howells 538cc1f0274SFrederic Weisbeckerconfig HAVE_IRQ_EXIT_ON_IRQ_STACK 539cc1f0274SFrederic Weisbecker bool 540cc1f0274SFrederic Weisbecker help 541cc1f0274SFrederic Weisbecker Architecture doesn't only execute the irq handler on the irq stack 542cc1f0274SFrederic Weisbecker but also irq_exit(). This way we can process softirqs on this irq 543cc1f0274SFrederic Weisbecker stack instead of switching to a new one when we call __do_softirq() 544cc1f0274SFrederic Weisbecker in the end of an hardirq. 545cc1f0274SFrederic Weisbecker This spares a stack switch and improves cache usage on softirq 546cc1f0274SFrederic Weisbecker processing. 547cc1f0274SFrederic Weisbecker 548235a8f02SKirill A. Shutemovconfig PGTABLE_LEVELS 549235a8f02SKirill A. Shutemov int 550235a8f02SKirill A. Shutemov default 2 551235a8f02SKirill A. Shutemov 5522b68f6caSKees Cookconfig ARCH_HAS_ELF_RANDOMIZE 5532b68f6caSKees Cook bool 5542b68f6caSKees Cook help 5552b68f6caSKees Cook An architecture supports choosing randomized locations for 5562b68f6caSKees Cook stack, mmap, brk, and ET_DYN. Defined functions: 5572b68f6caSKees Cook - arch_mmap_rnd() 558204db6edSKees Cook - arch_randomize_brk() 5592b68f6caSKees Cook 560d07e2259SDaniel Cashmanconfig HAVE_ARCH_MMAP_RND_BITS 561d07e2259SDaniel Cashman bool 562d07e2259SDaniel Cashman help 563d07e2259SDaniel Cashman An arch should select this symbol if it supports setting a variable 564d07e2259SDaniel Cashman number of bits for use in establishing the base address for mmap 565d07e2259SDaniel Cashman allocations, has MMU enabled and provides values for both: 566d07e2259SDaniel Cashman - ARCH_MMAP_RND_BITS_MIN 567d07e2259SDaniel Cashman - ARCH_MMAP_RND_BITS_MAX 568d07e2259SDaniel Cashman 5695f56a5dfSJiri Slabyconfig HAVE_EXIT_THREAD 5705f56a5dfSJiri Slaby bool 5715f56a5dfSJiri Slaby help 5725f56a5dfSJiri Slaby An architecture implements exit_thread. 5735f56a5dfSJiri Slaby 574d07e2259SDaniel Cashmanconfig ARCH_MMAP_RND_BITS_MIN 575d07e2259SDaniel Cashman int 576d07e2259SDaniel Cashman 577d07e2259SDaniel Cashmanconfig ARCH_MMAP_RND_BITS_MAX 578d07e2259SDaniel Cashman int 579d07e2259SDaniel Cashman 580d07e2259SDaniel Cashmanconfig ARCH_MMAP_RND_BITS_DEFAULT 581d07e2259SDaniel Cashman int 582d07e2259SDaniel Cashman 583d07e2259SDaniel Cashmanconfig ARCH_MMAP_RND_BITS 584d07e2259SDaniel Cashman int "Number of bits to use for ASLR of mmap base address" if EXPERT 585d07e2259SDaniel Cashman range ARCH_MMAP_RND_BITS_MIN ARCH_MMAP_RND_BITS_MAX 586d07e2259SDaniel Cashman default ARCH_MMAP_RND_BITS_DEFAULT if ARCH_MMAP_RND_BITS_DEFAULT 587d07e2259SDaniel Cashman default ARCH_MMAP_RND_BITS_MIN 588d07e2259SDaniel Cashman depends on HAVE_ARCH_MMAP_RND_BITS 589d07e2259SDaniel Cashman help 590d07e2259SDaniel Cashman This value can be used to select the number of bits to use to 591d07e2259SDaniel Cashman determine the random offset to the base address of vma regions 592d07e2259SDaniel Cashman resulting from mmap allocations. This value will be bounded 593d07e2259SDaniel Cashman by the architecture's minimum and maximum supported values. 594d07e2259SDaniel Cashman 595d07e2259SDaniel Cashman This value can be changed after boot using the 596d07e2259SDaniel Cashman /proc/sys/vm/mmap_rnd_bits tunable 597d07e2259SDaniel Cashman 598d07e2259SDaniel Cashmanconfig HAVE_ARCH_MMAP_RND_COMPAT_BITS 599d07e2259SDaniel Cashman bool 600d07e2259SDaniel Cashman help 601d07e2259SDaniel Cashman An arch should select this symbol if it supports running applications 602d07e2259SDaniel Cashman in compatibility mode, supports setting a variable number of bits for 603d07e2259SDaniel Cashman use in establishing the base address for mmap allocations, has MMU 604d07e2259SDaniel Cashman enabled and provides values for both: 605d07e2259SDaniel Cashman - ARCH_MMAP_RND_COMPAT_BITS_MIN 606d07e2259SDaniel Cashman - ARCH_MMAP_RND_COMPAT_BITS_MAX 607d07e2259SDaniel Cashman 608d07e2259SDaniel Cashmanconfig ARCH_MMAP_RND_COMPAT_BITS_MIN 609d07e2259SDaniel Cashman int 610d07e2259SDaniel Cashman 611d07e2259SDaniel Cashmanconfig ARCH_MMAP_RND_COMPAT_BITS_MAX 612d07e2259SDaniel Cashman int 613d07e2259SDaniel Cashman 614d07e2259SDaniel Cashmanconfig ARCH_MMAP_RND_COMPAT_BITS_DEFAULT 615d07e2259SDaniel Cashman int 616d07e2259SDaniel Cashman 617d07e2259SDaniel Cashmanconfig ARCH_MMAP_RND_COMPAT_BITS 618d07e2259SDaniel Cashman int "Number of bits to use for ASLR of mmap base address for compatible applications" if EXPERT 619d07e2259SDaniel Cashman range ARCH_MMAP_RND_COMPAT_BITS_MIN ARCH_MMAP_RND_COMPAT_BITS_MAX 620d07e2259SDaniel Cashman default ARCH_MMAP_RND_COMPAT_BITS_DEFAULT if ARCH_MMAP_RND_COMPAT_BITS_DEFAULT 621d07e2259SDaniel Cashman default ARCH_MMAP_RND_COMPAT_BITS_MIN 622d07e2259SDaniel Cashman depends on HAVE_ARCH_MMAP_RND_COMPAT_BITS 623d07e2259SDaniel Cashman help 624d07e2259SDaniel Cashman This value can be used to select the number of bits to use to 625d07e2259SDaniel Cashman determine the random offset to the base address of vma regions 626d07e2259SDaniel Cashman resulting from mmap allocations for compatible applications This 627d07e2259SDaniel Cashman value will be bounded by the architecture's minimum and maximum 628d07e2259SDaniel Cashman supported values. 629d07e2259SDaniel Cashman 630d07e2259SDaniel Cashman This value can be changed after boot using the 631d07e2259SDaniel Cashman /proc/sys/vm/mmap_rnd_compat_bits tunable 632d07e2259SDaniel Cashman 6331b028f78SDmitry Safonovconfig HAVE_ARCH_COMPAT_MMAP_BASES 6341b028f78SDmitry Safonov bool 6351b028f78SDmitry Safonov help 6361b028f78SDmitry Safonov This allows 64bit applications to invoke 32-bit mmap() syscall 6371b028f78SDmitry Safonov and vice-versa 32-bit applications to call 64-bit mmap(). 6381b028f78SDmitry Safonov Required for applications doing different bitness syscalls. 6391b028f78SDmitry Safonov 6403033f14aSJosh Triplettconfig HAVE_COPY_THREAD_TLS 6413033f14aSJosh Triplett bool 6423033f14aSJosh Triplett help 6433033f14aSJosh Triplett Architecture provides copy_thread_tls to accept tls argument via 6443033f14aSJosh Triplett normal C parameter passing, rather than extracting the syscall 6453033f14aSJosh Triplett argument from pt_regs. 6463033f14aSJosh Triplett 647b9ab5ebbSJosh Poimboeufconfig HAVE_STACK_VALIDATION 648b9ab5ebbSJosh Poimboeuf bool 649b9ab5ebbSJosh Poimboeuf help 650b9ab5ebbSJosh Poimboeuf Architecture supports the 'objtool check' host tool command, which 651b9ab5ebbSJosh Poimboeuf performs compile-time stack metadata validation. 652b9ab5ebbSJosh Poimboeuf 653af085d90SJosh Poimboeufconfig HAVE_RELIABLE_STACKTRACE 654af085d90SJosh Poimboeuf bool 655af085d90SJosh Poimboeuf help 656af085d90SJosh Poimboeuf Architecture has a save_stack_trace_tsk_reliable() function which 657af085d90SJosh Poimboeuf only returns a stack trace if it can guarantee the trace is reliable. 658af085d90SJosh Poimboeuf 659468a9428SGeorge Spelvinconfig HAVE_ARCH_HASH 660468a9428SGeorge Spelvin bool 661468a9428SGeorge Spelvin default n 662468a9428SGeorge Spelvin help 663468a9428SGeorge Spelvin If this is set, the architecture provides an <asm/hash.h> 664468a9428SGeorge Spelvin file which provides platform-specific implementations of some 665468a9428SGeorge Spelvin functions in <linux/hash.h> or fs/namei.c. 666468a9428SGeorge Spelvin 6673a495511SWilliam Breathitt Grayconfig ISA_BUS_API 6683a495511SWilliam Breathitt Gray def_bool ISA 6693a495511SWilliam Breathitt Gray 670d2125043SAl Viro# 671d2125043SAl Viro# ABI hall of shame 672d2125043SAl Viro# 673d2125043SAl Viroconfig CLONE_BACKWARDS 674d2125043SAl Viro bool 675d2125043SAl Viro help 676d2125043SAl Viro Architecture has tls passed as the 4th argument of clone(2), 677d2125043SAl Viro not the 5th one. 678d2125043SAl Viro 679d2125043SAl Viroconfig CLONE_BACKWARDS2 680d2125043SAl Viro bool 681d2125043SAl Viro help 682d2125043SAl Viro Architecture has the first two arguments of clone(2) swapped. 683d2125043SAl Viro 684dfa9771aSMichal Simekconfig CLONE_BACKWARDS3 685dfa9771aSMichal Simek bool 686dfa9771aSMichal Simek help 687dfa9771aSMichal Simek Architecture has tls passed as the 3rd argument of clone(2), 688dfa9771aSMichal Simek not the 5th one. 689dfa9771aSMichal Simek 690eaca6eaeSAl Viroconfig ODD_RT_SIGACTION 691eaca6eaeSAl Viro bool 692eaca6eaeSAl Viro help 693eaca6eaeSAl Viro Architecture has unusual rt_sigaction(2) arguments 694eaca6eaeSAl Viro 6950a0e8cdfSAl Viroconfig OLD_SIGSUSPEND 6960a0e8cdfSAl Viro bool 6970a0e8cdfSAl Viro help 6980a0e8cdfSAl Viro Architecture has old sigsuspend(2) syscall, of one-argument variety 6990a0e8cdfSAl Viro 7000a0e8cdfSAl Viroconfig OLD_SIGSUSPEND3 7010a0e8cdfSAl Viro bool 7020a0e8cdfSAl Viro help 7030a0e8cdfSAl Viro Even weirder antique ABI - three-argument sigsuspend(2) 7040a0e8cdfSAl Viro 705495dfbf7SAl Viroconfig OLD_SIGACTION 706495dfbf7SAl Viro bool 707495dfbf7SAl Viro help 708495dfbf7SAl Viro Architecture has old sigaction(2) syscall. Nope, not the same 709495dfbf7SAl Viro as OLD_SIGSUSPEND | OLD_SIGSUSPEND3 - alpha has sigsuspend(2), 710495dfbf7SAl Viro but fairly different variant of sigaction(2), thanks to OSF/1 711495dfbf7SAl Viro compatibility... 712495dfbf7SAl Viro 713495dfbf7SAl Viroconfig COMPAT_OLD_SIGACTION 714495dfbf7SAl Viro bool 715495dfbf7SAl Viro 716d4703ddaSDeepa Dinamaniconfig 64BIT_TIME 717d4703ddaSDeepa Dinamani def_bool ARCH_HAS_64BIT_TIME 718d4703ddaSDeepa Dinamani help 719d4703ddaSDeepa Dinamani This should be selected by all architectures that need to support 720d4703ddaSDeepa Dinamani new system calls with a 64-bit time_t. This is relevant on all 32-bit 721d4703ddaSDeepa Dinamani architectures, and 64-bit architectures as part of compat syscall 722d4703ddaSDeepa Dinamani handling. 723d4703ddaSDeepa Dinamani 72417435e5fSDeepa Dinamaniconfig COMPAT_32BIT_TIME 72517435e5fSDeepa Dinamani def_bool (!64BIT && 64BIT_TIME) || COMPAT 72617435e5fSDeepa Dinamani help 72717435e5fSDeepa Dinamani This enables 32 bit time_t support in addition to 64 bit time_t support. 72817435e5fSDeepa Dinamani This is relevant on all 32-bit architectures, and 64-bit architectures 72917435e5fSDeepa Dinamani as part of compat syscall handling. 73017435e5fSDeepa Dinamani 7310d4a619bSChristoph Hellwigconfig ARCH_NO_COHERENT_DMA_MMAP 7320d4a619bSChristoph Hellwig bool 7330d4a619bSChristoph Hellwig 734fff7fb0bSZhaoxiu Zengconfig CPU_NO_EFFICIENT_FFS 735fff7fb0bSZhaoxiu Zeng def_bool n 736fff7fb0bSZhaoxiu Zeng 737ba14a194SAndy Lutomirskiconfig HAVE_ARCH_VMAP_STACK 738ba14a194SAndy Lutomirski def_bool n 739ba14a194SAndy Lutomirski help 740ba14a194SAndy Lutomirski An arch should select this symbol if it can support kernel stacks 741ba14a194SAndy Lutomirski in vmalloc space. This means: 742ba14a194SAndy Lutomirski 743ba14a194SAndy Lutomirski - vmalloc space must be large enough to hold many kernel stacks. 744ba14a194SAndy Lutomirski This may rule out many 32-bit architectures. 745ba14a194SAndy Lutomirski 746ba14a194SAndy Lutomirski - Stacks in vmalloc space need to work reliably. For example, if 747ba14a194SAndy Lutomirski vmap page tables are created on demand, either this mechanism 748ba14a194SAndy Lutomirski needs to work while the stack points to a virtual address with 749ba14a194SAndy Lutomirski unpopulated page tables or arch code (switch_to() and switch_mm(), 750ba14a194SAndy Lutomirski most likely) needs to ensure that the stack's page table entries 751ba14a194SAndy Lutomirski are populated before running on a possibly unpopulated stack. 752ba14a194SAndy Lutomirski 753ba14a194SAndy Lutomirski - If the stack overflows into a guard page, something reasonable 754ba14a194SAndy Lutomirski should happen. The definition of "reasonable" is flexible, but 755ba14a194SAndy Lutomirski instantly rebooting without logging anything would be unfriendly. 756ba14a194SAndy Lutomirski 757ba14a194SAndy Lutomirskiconfig VMAP_STACK 758ba14a194SAndy Lutomirski default y 759ba14a194SAndy Lutomirski bool "Use a virtually-mapped stack" 760ba14a194SAndy Lutomirski depends on HAVE_ARCH_VMAP_STACK && !KASAN 761ba14a194SAndy Lutomirski ---help--- 762ba14a194SAndy Lutomirski Enable this if you want the use virtually-mapped kernel stacks 763ba14a194SAndy Lutomirski with guard pages. This causes kernel stack overflows to be 764ba14a194SAndy Lutomirski caught immediately rather than causing difficult-to-diagnose 765ba14a194SAndy Lutomirski corruption. 766ba14a194SAndy Lutomirski 767ba14a194SAndy Lutomirski This is presently incompatible with KASAN because KASAN expects 768ba14a194SAndy Lutomirski the stack to map directly to the KASAN shadow map using a formula 769ba14a194SAndy Lutomirski that is incorrect if the stack is in vmalloc space. 770ba14a194SAndy Lutomirski 771ad21fc4fSLaura Abbottconfig ARCH_OPTIONAL_KERNEL_RWX 772ad21fc4fSLaura Abbott def_bool n 773ad21fc4fSLaura Abbott 774ad21fc4fSLaura Abbottconfig ARCH_OPTIONAL_KERNEL_RWX_DEFAULT 775ad21fc4fSLaura Abbott def_bool n 776ad21fc4fSLaura Abbott 777ad21fc4fSLaura Abbottconfig ARCH_HAS_STRICT_KERNEL_RWX 778ad21fc4fSLaura Abbott def_bool n 779ad21fc4fSLaura Abbott 7800f5bf6d0SLaura Abbottconfig STRICT_KERNEL_RWX 781ad21fc4fSLaura Abbott bool "Make kernel text and rodata read-only" if ARCH_OPTIONAL_KERNEL_RWX 782ad21fc4fSLaura Abbott depends on ARCH_HAS_STRICT_KERNEL_RWX 783ad21fc4fSLaura Abbott default !ARCH_OPTIONAL_KERNEL_RWX || ARCH_OPTIONAL_KERNEL_RWX_DEFAULT 784ad21fc4fSLaura Abbott help 785ad21fc4fSLaura Abbott If this is set, kernel text and rodata memory will be made read-only, 786ad21fc4fSLaura Abbott and non-text memory will be made non-executable. This provides 787ad21fc4fSLaura Abbott protection against certain security exploits (e.g. executing the heap 788ad21fc4fSLaura Abbott or modifying text) 789ad21fc4fSLaura Abbott 790ad21fc4fSLaura Abbott These features are considered standard security practice these days. 791ad21fc4fSLaura Abbott You should say Y here in almost all cases. 792ad21fc4fSLaura Abbott 793ad21fc4fSLaura Abbottconfig ARCH_HAS_STRICT_MODULE_RWX 794ad21fc4fSLaura Abbott def_bool n 795ad21fc4fSLaura Abbott 7960f5bf6d0SLaura Abbottconfig STRICT_MODULE_RWX 797ad21fc4fSLaura Abbott bool "Set loadable kernel module data as NX and text as RO" if ARCH_OPTIONAL_KERNEL_RWX 798ad21fc4fSLaura Abbott depends on ARCH_HAS_STRICT_MODULE_RWX && MODULES 799ad21fc4fSLaura Abbott default !ARCH_OPTIONAL_KERNEL_RWX || ARCH_OPTIONAL_KERNEL_RWX_DEFAULT 800ad21fc4fSLaura Abbott help 801ad21fc4fSLaura Abbott If this is set, module text and rodata memory will be made read-only, 802ad21fc4fSLaura Abbott and non-text memory will be made non-executable. This provides 803ad21fc4fSLaura Abbott protection against certain security exploits (e.g. writing to text) 804ad21fc4fSLaura Abbott 805ea8c64acSChristoph Hellwig# select if the architecture provides an asm/dma-direct.h header 806ea8c64acSChristoph Hellwigconfig ARCH_HAS_PHYS_TO_DMA 807ea8c64acSChristoph Hellwig bool 808ea8c64acSChristoph Hellwig 8097a46ec0eSKees Cookconfig ARCH_HAS_REFCOUNT 8107a46ec0eSKees Cook bool 8117a46ec0eSKees Cook help 8127a46ec0eSKees Cook An architecture selects this when it has implemented refcount_t 8137a46ec0eSKees Cook using open coded assembly primitives that provide an optimized 8147a46ec0eSKees Cook refcount_t implementation, possibly at the expense of some full 8157a46ec0eSKees Cook refcount state checks of CONFIG_REFCOUNT_FULL=y. 8167a46ec0eSKees Cook 8177a46ec0eSKees Cook The refcount overflow check behavior, however, must be retained. 8187a46ec0eSKees Cook Catching overflows is the primary security concern for protecting 8197a46ec0eSKees Cook against bugs in reference counts. 8207a46ec0eSKees Cook 821fd25d19fSKees Cookconfig REFCOUNT_FULL 822fd25d19fSKees Cook bool "Perform full reference count validation at the expense of speed" 823fd25d19fSKees Cook help 824fd25d19fSKees Cook Enabling this switches the refcounting infrastructure from a fast 825fd25d19fSKees Cook unchecked atomic_t implementation to a fully state checked 826fd25d19fSKees Cook implementation, which can be (slightly) slower but provides protections 827fd25d19fSKees Cook against various use-after-free conditions that can be used in 828fd25d19fSKees Cook security flaw exploits. 829fd25d19fSKees Cook 8302521f2c2SPeter Oberparleitersource "kernel/gcov/Kconfig" 83145332b1bSMasahiro Yamada 83245332b1bSMasahiro Yamadasource "scripts/gcc-plugins/Kconfig" 833