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 19942a0bb3fSPetr Mladekconfig HAVE_NMI 20042a0bb3fSPetr Mladek bool 20142a0bb3fSPetr Mladek 2021f5a4ad9SRoland McGrath# 2031f5a4ad9SRoland McGrath# An arch should select this if it provides all these things: 2041f5a4ad9SRoland McGrath# 2051f5a4ad9SRoland McGrath# task_pt_regs() in asm/processor.h or asm/ptrace.h 2061f5a4ad9SRoland McGrath# arch_has_single_step() if there is hardware single-step support 2071f5a4ad9SRoland McGrath# arch_has_block_step() if there is hardware block-step support 2081f5a4ad9SRoland McGrath# asm/syscall.h supplying asm-generic/syscall.h interface 2091f5a4ad9SRoland McGrath# linux/regset.h user_regset interfaces 2101f5a4ad9SRoland McGrath# CORE_DUMP_USE_REGSET #define'd in linux/elf.h 2111f5a4ad9SRoland McGrath# TIF_SYSCALL_TRACE calls tracehook_report_syscall_{entry,exit} 2121f5a4ad9SRoland McGrath# TIF_NOTIFY_RESUME calls tracehook_notify_resume() 2131f5a4ad9SRoland McGrath# signal delivery calls tracehook_signal_handler() 2141f5a4ad9SRoland McGrath# 2151f5a4ad9SRoland McGrathconfig HAVE_ARCH_TRACEHOOK 2169ba16087SJan Beulich bool 2171f5a4ad9SRoland McGrath 218c64be2bbSMarek Szyprowskiconfig HAVE_DMA_CONTIGUOUS 219c64be2bbSMarek Szyprowski bool 220c64be2bbSMarek Szyprowski 22129d5e047SThomas Gleixnerconfig GENERIC_SMP_IDLE_THREAD 22229d5e047SThomas Gleixner bool 22329d5e047SThomas Gleixner 224485cf5daSKevin Hilmanconfig GENERIC_IDLE_POLL_SETUP 225485cf5daSKevin Hilman bool 226485cf5daSKevin Hilman 2276974f0c4SDaniel Micayconfig ARCH_HAS_FORTIFY_SOURCE 2286974f0c4SDaniel Micay bool 2296974f0c4SDaniel Micay help 2306974f0c4SDaniel Micay An architecture should select this when it can successfully 2316974f0c4SDaniel Micay build and run with CONFIG_FORTIFY_SOURCE. 2326974f0c4SDaniel Micay 233d2852a22SDaniel Borkmann# Select if arch has all set_memory_ro/rw/x/nx() functions in asm/cacheflush.h 234d2852a22SDaniel Borkmannconfig ARCH_HAS_SET_MEMORY 235d2852a22SDaniel Borkmann bool 236d2852a22SDaniel Borkmann 237a6359d1eSThomas Gleixner# Select if arch init_task initializer is different to init/init_task.c 238a6359d1eSThomas Gleixnerconfig ARCH_INIT_TASK 239a4a2eb49SThomas Gleixner bool 240a4a2eb49SThomas Gleixner 241f5e10287SThomas Gleixner# Select if arch has its private alloc_task_struct() function 242f5e10287SThomas Gleixnerconfig ARCH_TASK_STRUCT_ALLOCATOR 243f5e10287SThomas Gleixner bool 244f5e10287SThomas Gleixner 245b235beeaSLinus Torvalds# Select if arch has its private alloc_thread_stack() function 246b235beeaSLinus Torvaldsconfig ARCH_THREAD_STACK_ALLOCATOR 247f5e10287SThomas Gleixner bool 248f5e10287SThomas Gleixner 2495aaeb5c0SIngo Molnar# Select if arch wants to size task_struct dynamically via arch_task_struct_size: 2505aaeb5c0SIngo Molnarconfig ARCH_WANTS_DYNAMIC_TASK_STRUCT 2515aaeb5c0SIngo Molnar bool 2525aaeb5c0SIngo Molnar 253f850c30cSHeiko Carstensconfig HAVE_REGS_AND_STACK_ACCESS_API 254f850c30cSHeiko Carstens bool 255e01292b1SHeiko Carstens help 256e01292b1SHeiko Carstens This symbol should be selected by an architecure if it supports 257e01292b1SHeiko Carstens the API needed to access registers and stack entries from pt_regs, 258e01292b1SHeiko Carstens declared in asm/ptrace.h 259e01292b1SHeiko Carstens For example the kprobes-based event tracer needs this API. 260f850c30cSHeiko Carstens 2619483a578SDavid Brownellconfig HAVE_CLK 2629ba16087SJan Beulich bool 2639483a578SDavid Brownell help 2649483a578SDavid Brownell The <linux/clk.h> calls support software clock gating and 2659483a578SDavid Brownell thus are a key power management tool on many systems. 2669483a578SDavid Brownell 2675ee00bd4SJoerg Roedelconfig HAVE_DMA_API_DEBUG 2685ee00bd4SJoerg Roedel bool 26936cd3c9fSHeiko Carstens 27062a038d3SK.Prasadconfig HAVE_HW_BREAKPOINT 27162a038d3SK.Prasad bool 27299e8c5a3SFrederic Weisbecker depends on PERF_EVENTS 27362a038d3SK.Prasad 2740102752eSFrederic Weisbeckerconfig HAVE_MIXED_BREAKPOINTS_REGS 2750102752eSFrederic Weisbecker bool 2760102752eSFrederic Weisbecker depends on HAVE_HW_BREAKPOINT 2770102752eSFrederic Weisbecker help 2780102752eSFrederic Weisbecker Depending on the arch implementation of hardware breakpoints, 2790102752eSFrederic Weisbecker some of them have separate registers for data and instruction 2800102752eSFrederic Weisbecker breakpoints addresses, others have mixed registers to store 2810102752eSFrederic Weisbecker them but define the access type in a control register. 2820102752eSFrederic Weisbecker Select this option if your arch implements breakpoints under the 2830102752eSFrederic Weisbecker latter fashion. 2840102752eSFrederic Weisbecker 2857c68af6eSAvi Kivityconfig HAVE_USER_RETURN_NOTIFIER 2867c68af6eSAvi Kivity bool 287a1922ed6SIngo Molnar 288c01d4323SFrederic Weisbeckerconfig HAVE_PERF_EVENTS_NMI 289c01d4323SFrederic Weisbecker bool 29023637d47SFrederic Weisbecker help 29123637d47SFrederic Weisbecker System hardware can generate an NMI using the perf event 29223637d47SFrederic Weisbecker subsystem. Also has support for calculating CPU cycle events 29323637d47SFrederic Weisbecker to determine how many clock cycles in a given period. 294c01d4323SFrederic Weisbecker 29505a4a952SNicholas Pigginconfig HAVE_HARDLOCKUP_DETECTOR_PERF 29605a4a952SNicholas Piggin bool 29705a4a952SNicholas Piggin depends on HAVE_PERF_EVENTS_NMI 29805a4a952SNicholas Piggin help 29905a4a952SNicholas Piggin The arch chooses to use the generic perf-NMI-based hardlockup 30005a4a952SNicholas Piggin detector. Must define HAVE_PERF_EVENTS_NMI. 30105a4a952SNicholas Piggin 30205a4a952SNicholas Pigginconfig HAVE_NMI_WATCHDOG 30305a4a952SNicholas Piggin depends on HAVE_NMI 30405a4a952SNicholas Piggin bool 30505a4a952SNicholas Piggin help 30605a4a952SNicholas Piggin The arch provides a low level NMI watchdog. It provides 30705a4a952SNicholas Piggin asm/nmi.h, and defines its own arch_touch_nmi_watchdog(). 30805a4a952SNicholas Piggin 30905a4a952SNicholas Pigginconfig HAVE_HARDLOCKUP_DETECTOR_ARCH 31005a4a952SNicholas Piggin bool 31105a4a952SNicholas Piggin select HAVE_NMI_WATCHDOG 31205a4a952SNicholas Piggin help 31305a4a952SNicholas Piggin The arch chooses to provide its own hardlockup detector, which is 31405a4a952SNicholas Piggin a superset of the HAVE_NMI_WATCHDOG. It also conforms to config 31505a4a952SNicholas Piggin interfaces and parameters provided by hardlockup detector subsystem. 31605a4a952SNicholas Piggin 317c5e63197SJiri Olsaconfig HAVE_PERF_REGS 318c5e63197SJiri Olsa bool 319c5e63197SJiri Olsa help 320c5e63197SJiri Olsa Support selective register dumps for perf events. This includes 321c5e63197SJiri Olsa bit-mapping of each registers and a unique architecture id. 322c5e63197SJiri Olsa 323c5ebcedbSJiri Olsaconfig HAVE_PERF_USER_STACK_DUMP 324c5ebcedbSJiri Olsa bool 325c5ebcedbSJiri Olsa help 326c5ebcedbSJiri Olsa Support user stack dumps for perf event samples. This needs 327c5ebcedbSJiri Olsa access to the user stack pointer which is not unified across 328c5ebcedbSJiri Olsa architectures. 329c5ebcedbSJiri Olsa 330bf5438fcSJason Baronconfig HAVE_ARCH_JUMP_LABEL 331bf5438fcSJason Baron bool 332bf5438fcSJason Baron 33326723911SPeter Zijlstraconfig HAVE_RCU_TABLE_FREE 33426723911SPeter Zijlstra bool 33526723911SPeter Zijlstra 336df013ffbSHuang Yingconfig ARCH_HAVE_NMI_SAFE_CMPXCHG 337df013ffbSHuang Ying bool 338df013ffbSHuang Ying 33943570fd2SHeiko Carstensconfig HAVE_ALIGNED_STRUCT_PAGE 34043570fd2SHeiko Carstens bool 34143570fd2SHeiko Carstens help 34243570fd2SHeiko Carstens This makes sure that struct pages are double word aligned and that 34343570fd2SHeiko Carstens e.g. the SLUB allocator can perform double word atomic operations 34443570fd2SHeiko Carstens on a struct page for better performance. However selecting this 34543570fd2SHeiko Carstens might increase the size of a struct page by a word. 34643570fd2SHeiko Carstens 3474156153cSHeiko Carstensconfig HAVE_CMPXCHG_LOCAL 3484156153cSHeiko Carstens bool 3494156153cSHeiko Carstens 3502565409fSHeiko Carstensconfig HAVE_CMPXCHG_DOUBLE 3512565409fSHeiko Carstens bool 3522565409fSHeiko Carstens 35377e58496SPaul E. McKenneyconfig ARCH_WEAK_RELEASE_ACQUIRE 35477e58496SPaul E. McKenney bool 35577e58496SPaul E. McKenney 356c1d7e01dSWill Deaconconfig ARCH_WANT_IPC_PARSE_VERSION 357c1d7e01dSWill Deacon bool 358c1d7e01dSWill Deacon 359c1d7e01dSWill Deaconconfig ARCH_WANT_COMPAT_IPC_PARSE_VERSION 360c1d7e01dSWill Deacon bool 361c1d7e01dSWill Deacon 36248b25c43SChris Metcalfconfig ARCH_WANT_OLD_COMPAT_IPC 363c1d7e01dSWill Deacon select ARCH_WANT_COMPAT_IPC_PARSE_VERSION 36448b25c43SChris Metcalf bool 36548b25c43SChris Metcalf 366e2cfabdfSWill Drewryconfig HAVE_ARCH_SECCOMP_FILTER 367e2cfabdfSWill Drewry bool 368e2cfabdfSWill Drewry help 369fb0fadf9SWill Drewry An arch should select this symbol if it provides all of these things: 370bb6ea430SWill Drewry - syscall_get_arch() 371bb6ea430SWill Drewry - syscall_get_arguments() 372bb6ea430SWill Drewry - syscall_rollback() 373bb6ea430SWill Drewry - syscall_set_return_value() 374fb0fadf9SWill Drewry - SIGSYS siginfo_t support 375fb0fadf9SWill Drewry - secure_computing is called from a ptrace_event()-safe context 376fb0fadf9SWill Drewry - secure_computing return value is checked and a return value of -1 377fb0fadf9SWill Drewry results in the system call being skipped immediately. 37848dc92b9SKees Cook - seccomp syscall wired up 379e2cfabdfSWill Drewry 380e2cfabdfSWill Drewryconfig SECCOMP_FILTER 381e2cfabdfSWill Drewry def_bool y 382e2cfabdfSWill Drewry depends on HAVE_ARCH_SECCOMP_FILTER && SECCOMP && NET 383e2cfabdfSWill Drewry help 384e2cfabdfSWill Drewry Enable tasks to build secure computing environments defined 385e2cfabdfSWill Drewry in terms of Berkeley Packet Filter programs which implement 386e2cfabdfSWill Drewry task-defined system call filtering polices. 387e2cfabdfSWill Drewry 388e2cfabdfSWill Drewry See Documentation/prctl/seccomp_filter.txt for details. 389e2cfabdfSWill Drewry 3906b90bd4bSEmese Revfyconfig HAVE_GCC_PLUGINS 3916b90bd4bSEmese Revfy bool 3926b90bd4bSEmese Revfy help 3936b90bd4bSEmese Revfy An arch should select this symbol if it supports building with 3946b90bd4bSEmese Revfy GCC plugins. 3956b90bd4bSEmese Revfy 3966b90bd4bSEmese Revfymenuconfig GCC_PLUGINS 3976b90bd4bSEmese Revfy bool "GCC plugins" 3986b90bd4bSEmese Revfy depends on HAVE_GCC_PLUGINS 399a519167eSKees Cook depends on !COMPILE_TEST 4006b90bd4bSEmese Revfy help 4016b90bd4bSEmese Revfy GCC plugins are loadable modules that provide extra features to the 4026b90bd4bSEmese Revfy compiler. They are useful for runtime instrumentation and static analysis. 4036b90bd4bSEmese Revfy 4046b90bd4bSEmese Revfy See Documentation/gcc-plugins.txt for details. 4056b90bd4bSEmese Revfy 4060dae776cSEmese Revfyconfig GCC_PLUGIN_CYC_COMPLEXITY 407215e2aa6SKees Cook bool "Compute the cyclomatic complexity of a function" if EXPERT 4080dae776cSEmese Revfy depends on GCC_PLUGINS 409215e2aa6SKees Cook depends on !COMPILE_TEST 4100dae776cSEmese Revfy help 4110dae776cSEmese Revfy The complexity M of a function's control flow graph is defined as: 4120dae776cSEmese Revfy M = E - N + 2P 4130dae776cSEmese Revfy where 4140dae776cSEmese Revfy 4150dae776cSEmese Revfy E = the number of edges 4160dae776cSEmese Revfy N = the number of nodes 4170dae776cSEmese Revfy P = the number of connected components (exit nodes). 4180dae776cSEmese Revfy 419215e2aa6SKees Cook Enabling this plugin reports the complexity to stderr during the 420215e2aa6SKees Cook build. It mainly serves as a simple example of how to create a 421215e2aa6SKees Cook gcc plugin for the kernel. 422215e2aa6SKees Cook 423543c37cbSEmese Revfyconfig GCC_PLUGIN_SANCOV 424543c37cbSEmese Revfy bool 425543c37cbSEmese Revfy depends on GCC_PLUGINS 426543c37cbSEmese Revfy help 427543c37cbSEmese Revfy This plugin inserts a __sanitizer_cov_trace_pc() call at the start of 428543c37cbSEmese Revfy basic blocks. It supports all gcc versions with plugin support (from 429543c37cbSEmese Revfy gcc-4.5 on). It is based on the commit "Add fuzzing coverage support" 430543c37cbSEmese Revfy by Dmitry Vyukov <dvyukov@google.com>. 431543c37cbSEmese Revfy 43238addce8SEmese Revfyconfig GCC_PLUGIN_LATENT_ENTROPY 43338addce8SEmese Revfy bool "Generate some entropy during boot and runtime" 43438addce8SEmese Revfy depends on GCC_PLUGINS 43538addce8SEmese Revfy help 43638addce8SEmese Revfy By saying Y here the kernel will instrument some kernel code to 43738addce8SEmese Revfy extract some entropy from both original and artificially created 43838addce8SEmese Revfy program state. This will help especially embedded systems where 43938addce8SEmese Revfy there is little 'natural' source of entropy normally. The cost 44038addce8SEmese Revfy is some slowdown of the boot process (about 0.5%) and fork and 44138addce8SEmese Revfy irq processing. 44238addce8SEmese Revfy 44338addce8SEmese Revfy Note that entropy extracted this way is not cryptographically 44438addce8SEmese Revfy secure! 44538addce8SEmese Revfy 44638addce8SEmese Revfy This plugin was ported from grsecurity/PaX. More information at: 44738addce8SEmese Revfy * https://grsecurity.net/ 44838addce8SEmese Revfy * https://pax.grsecurity.net/ 44938addce8SEmese Revfy 450c61f13eaSKees Cookconfig GCC_PLUGIN_STRUCTLEAK 451c61f13eaSKees Cook bool "Force initialization of variables containing userspace addresses" 452c61f13eaSKees Cook depends on GCC_PLUGINS 453c61f13eaSKees Cook help 454f136e090SJean Delvare This plugin zero-initializes any structures containing a 455c61f13eaSKees Cook __user attribute. This can prevent some classes of information 456c61f13eaSKees Cook exposures. 457c61f13eaSKees Cook 458c61f13eaSKees Cook This plugin was ported from grsecurity/PaX. More information at: 459c61f13eaSKees Cook * https://grsecurity.net/ 460c61f13eaSKees Cook * https://pax.grsecurity.net/ 461c61f13eaSKees Cook 462f7dd2507SArd Biesheuvelconfig GCC_PLUGIN_STRUCTLEAK_BYREF_ALL 463f7dd2507SArd Biesheuvel bool "Force initialize all struct type variables passed by reference" 464f7dd2507SArd Biesheuvel depends on GCC_PLUGIN_STRUCTLEAK 465f7dd2507SArd Biesheuvel help 466f7dd2507SArd Biesheuvel Zero initialize any struct type local variable that may be passed by 467f7dd2507SArd Biesheuvel reference without having been initialized. 468f7dd2507SArd Biesheuvel 469c61f13eaSKees Cookconfig GCC_PLUGIN_STRUCTLEAK_VERBOSE 470c61f13eaSKees Cook bool "Report forcefully initialized variables" 471c61f13eaSKees Cook depends on GCC_PLUGIN_STRUCTLEAK 472c61f13eaSKees Cook depends on !COMPILE_TEST 473c61f13eaSKees Cook help 474c61f13eaSKees Cook This option will cause a warning to be printed each time the 475c61f13eaSKees Cook structleak plugin finds a variable it thinks needs to be 476c61f13eaSKees Cook initialized. Since not all existing initializers are detected 477c61f13eaSKees Cook by the plugin, this can produce false positive warnings. 478c61f13eaSKees Cook 479313dd1b6SKees Cookconfig GCC_PLUGIN_RANDSTRUCT 480313dd1b6SKees Cook bool "Randomize layout of sensitive kernel structures" 481313dd1b6SKees Cook depends on GCC_PLUGINS 482313dd1b6SKees Cook select MODVERSIONS if MODULES 483313dd1b6SKees Cook help 4849225331bSKees Cook If you say Y here, the layouts of structures that are entirely 4859225331bSKees Cook function pointers (and have not been manually annotated with 4869225331bSKees Cook __no_randomize_layout), or structures that have been explicitly 4879225331bSKees Cook marked with __randomize_layout, will be randomized at compile-time. 4889225331bSKees Cook This can introduce the requirement of an additional information 4899225331bSKees Cook exposure vulnerability for exploits targeting these structure 4909225331bSKees Cook types. 491313dd1b6SKees Cook 492313dd1b6SKees Cook Enabling this feature will introduce some performance impact, 493313dd1b6SKees Cook slightly increase memory usage, and prevent the use of forensic 494313dd1b6SKees Cook tools like Volatility against the system (unless the kernel 495313dd1b6SKees Cook source tree isn't cleaned after kernel installation). 496313dd1b6SKees Cook 497313dd1b6SKees Cook The seed used for compilation is located at 498313dd1b6SKees Cook scripts/gcc-plgins/randomize_layout_seed.h. It remains after 499313dd1b6SKees Cook a make clean to allow for external modules to be compiled with 500313dd1b6SKees Cook the existing seed and will be removed by a make mrproper or 501313dd1b6SKees Cook make distclean. 502313dd1b6SKees Cook 503313dd1b6SKees Cook Note that the implementation requires gcc 4.7 or newer. 504313dd1b6SKees Cook 505313dd1b6SKees Cook This plugin was ported from grsecurity/PaX. More information at: 506313dd1b6SKees Cook * https://grsecurity.net/ 507313dd1b6SKees Cook * https://pax.grsecurity.net/ 508313dd1b6SKees Cook 509313dd1b6SKees Cookconfig GCC_PLUGIN_RANDSTRUCT_PERFORMANCE 510313dd1b6SKees Cook bool "Use cacheline-aware structure randomization" 511313dd1b6SKees Cook depends on GCC_PLUGIN_RANDSTRUCT 512313dd1b6SKees Cook depends on !COMPILE_TEST 513313dd1b6SKees Cook help 514313dd1b6SKees Cook If you say Y here, the RANDSTRUCT randomization will make a 515313dd1b6SKees Cook best effort at restricting randomization to cacheline-sized 516313dd1b6SKees Cook groups of elements. It will further not randomize bitfields 517313dd1b6SKees Cook in structures. This reduces the performance hit of RANDSTRUCT 518313dd1b6SKees Cook at the cost of weakened randomization. 519313dd1b6SKees Cook 52019952a92SKees Cookconfig HAVE_CC_STACKPROTECTOR 52119952a92SKees Cook bool 52219952a92SKees Cook help 52319952a92SKees Cook An arch should select this symbol if: 52419952a92SKees Cook - its compiler supports the -fstack-protector option 52519952a92SKees Cook - it has implemented a stack canary (e.g. __stack_chk_guard) 52619952a92SKees Cook 52719952a92SKees Cookconfig CC_STACKPROTECTOR 5288779657dSKees Cook def_bool n 52919952a92SKees Cook help 5308779657dSKees Cook Set when a stack-protector mode is enabled, so that the build 5318779657dSKees Cook can enable kernel-side support for the GCC feature. 5328779657dSKees Cook 5338779657dSKees Cookchoice 5348779657dSKees Cook prompt "Stack Protector buffer overflow detection" 5358779657dSKees Cook depends on HAVE_CC_STACKPROTECTOR 5368779657dSKees Cook default CC_STACKPROTECTOR_NONE 5378779657dSKees Cook help 5388779657dSKees Cook This option turns on the "stack-protector" GCC feature. This 53919952a92SKees Cook feature puts, at the beginning of functions, a canary value on 54019952a92SKees Cook the stack just before the return address, and validates 54119952a92SKees Cook the value just before actually returning. Stack based buffer 54219952a92SKees Cook overflows (that need to overwrite this return address) now also 54319952a92SKees Cook overwrite the canary, which gets detected and the attack is then 54419952a92SKees Cook neutralized via a kernel panic. 54519952a92SKees Cook 5468779657dSKees Cookconfig CC_STACKPROTECTOR_NONE 5478779657dSKees Cook bool "None" 5488779657dSKees Cook help 5498779657dSKees Cook Disable "stack-protector" GCC feature. 5508779657dSKees Cook 5518779657dSKees Cookconfig CC_STACKPROTECTOR_REGULAR 5528779657dSKees Cook bool "Regular" 5538779657dSKees Cook select CC_STACKPROTECTOR 5548779657dSKees Cook help 5558779657dSKees Cook Functions will have the stack-protector canary logic added if they 5568779657dSKees Cook have an 8-byte or larger character array on the stack. 5578779657dSKees Cook 55819952a92SKees Cook This feature requires gcc version 4.2 or above, or a distribution 5598779657dSKees Cook gcc with the feature backported ("-fstack-protector"). 5608779657dSKees Cook 5618779657dSKees Cook On an x86 "defconfig" build, this feature adds canary checks to 5628779657dSKees Cook about 3% of all kernel functions, which increases kernel code size 5638779657dSKees Cook by about 0.3%. 5648779657dSKees Cook 5658779657dSKees Cookconfig CC_STACKPROTECTOR_STRONG 5668779657dSKees Cook bool "Strong" 5678779657dSKees Cook select CC_STACKPROTECTOR 5688779657dSKees Cook help 5698779657dSKees Cook Functions will have the stack-protector canary logic added in any 5708779657dSKees Cook of the following conditions: 5718779657dSKees Cook 5728779657dSKees Cook - local variable's address used as part of the right hand side of an 5738779657dSKees Cook assignment or function argument 5748779657dSKees Cook - local variable is an array (or union containing an array), 5758779657dSKees Cook regardless of array type or length 5768779657dSKees Cook - uses register local variables 5778779657dSKees Cook 5788779657dSKees Cook This feature requires gcc version 4.9 or above, or a distribution 5798779657dSKees Cook gcc with the feature backported ("-fstack-protector-strong"). 5808779657dSKees Cook 5818779657dSKees Cook On an x86 "defconfig" build, this feature adds canary checks to 5828779657dSKees Cook about 20% of all kernel functions, which increases the kernel code 5838779657dSKees Cook size by about 2%. 5848779657dSKees Cook 5858779657dSKees Cookendchoice 58619952a92SKees Cook 587a5967db9SStephen Rothwellconfig THIN_ARCHIVES 588799c4341SNicholas Piggin def_bool y 589a5967db9SStephen Rothwell help 590a5967db9SStephen Rothwell Select this if the architecture wants to use thin archives 591a5967db9SStephen Rothwell instead of ld -r to create the built-in.o files. 592a5967db9SStephen Rothwell 593b67067f1SNicholas Pigginconfig LD_DEAD_CODE_DATA_ELIMINATION 594b67067f1SNicholas Piggin bool 595b67067f1SNicholas Piggin help 596b67067f1SNicholas Piggin Select this if the architecture wants to do dead code and 597b67067f1SNicholas Piggin data elimination with the linker by compiling with 598b67067f1SNicholas Piggin -ffunction-sections -fdata-sections and linking with 599b67067f1SNicholas Piggin --gc-sections. 600b67067f1SNicholas Piggin 601b67067f1SNicholas Piggin This requires that the arch annotates or otherwise protects 602b67067f1SNicholas Piggin its external entry points from being discarded. Linker scripts 603b67067f1SNicholas Piggin must also merge .text.*, .data.*, and .bss.* correctly into 6040f4c4af0SNicholas Piggin output sections. Care must be taken not to pull in unrelated 6050f4c4af0SNicholas Piggin sections (e.g., '.text.init'). Typically '.' in section names 6060f4c4af0SNicholas Piggin is used to distinguish them from label names / C identifiers. 607b67067f1SNicholas Piggin 6080f60a8efSKees Cookconfig HAVE_ARCH_WITHIN_STACK_FRAMES 6090f60a8efSKees Cook bool 6100f60a8efSKees Cook help 6110f60a8efSKees Cook An architecture should select this if it can walk the kernel stack 6120f60a8efSKees Cook frames to determine if an object is part of either the arguments 6130f60a8efSKees Cook or local variables (i.e. that it excludes saved return addresses, 6140f60a8efSKees Cook and similar) by implementing an inline arch_within_stack_frames(), 6150f60a8efSKees Cook which is used by CONFIG_HARDENED_USERCOPY. 6160f60a8efSKees Cook 61791d1aa43SFrederic Weisbeckerconfig HAVE_CONTEXT_TRACKING 6182b1d5024SFrederic Weisbecker bool 6192b1d5024SFrederic Weisbecker help 62091d1aa43SFrederic Weisbecker Provide kernel/user boundaries probes necessary for subsystems 62191d1aa43SFrederic Weisbecker that need it, such as userspace RCU extended quiescent state. 62291d1aa43SFrederic Weisbecker Syscalls need to be wrapped inside user_exit()-user_enter() through 62391d1aa43SFrederic Weisbecker the slow path using TIF_NOHZ flag. Exceptions handlers must be 62491d1aa43SFrederic Weisbecker wrapped as well. Irqs are already protected inside 62591d1aa43SFrederic Weisbecker rcu_irq_enter/rcu_irq_exit() but preemption or signal handling on 62691d1aa43SFrederic Weisbecker irq exit still need to be protected. 6272b1d5024SFrederic Weisbecker 628b952741cSFrederic Weisbeckerconfig HAVE_VIRT_CPU_ACCOUNTING 629b952741cSFrederic Weisbecker bool 630b952741cSFrederic Weisbecker 63140565b5aSStanislaw Gruszkaconfig ARCH_HAS_SCALED_CPUTIME 63240565b5aSStanislaw Gruszka bool 63340565b5aSStanislaw Gruszka 634554b0004SKevin Hilmanconfig HAVE_VIRT_CPU_ACCOUNTING_GEN 635554b0004SKevin Hilman bool 636554b0004SKevin Hilman default y if 64BIT 637554b0004SKevin Hilman help 638554b0004SKevin Hilman With VIRT_CPU_ACCOUNTING_GEN, cputime_t becomes 64-bit. 639554b0004SKevin Hilman Before enabling this option, arch code must be audited 640554b0004SKevin Hilman to ensure there are no races in concurrent read/write of 641554b0004SKevin Hilman cputime_t. For example, reading/writing 64-bit cputime_t on 642554b0004SKevin Hilman some 32-bit arches may require multiple accesses, so proper 643554b0004SKevin Hilman locking is needed to protect against concurrent accesses. 644554b0004SKevin Hilman 645554b0004SKevin Hilman 646fdf9c356SFrederic Weisbeckerconfig HAVE_IRQ_TIME_ACCOUNTING 647fdf9c356SFrederic Weisbecker bool 648fdf9c356SFrederic Weisbecker help 649fdf9c356SFrederic Weisbecker Archs need to ensure they use a high enough resolution clock to 650fdf9c356SFrederic Weisbecker support irq time accounting and then call enable_sched_clock_irqtime(). 651fdf9c356SFrederic Weisbecker 65215626062SGerald Schaeferconfig HAVE_ARCH_TRANSPARENT_HUGEPAGE 65315626062SGerald Schaefer bool 65415626062SGerald Schaefer 655a00cc7d9SMatthew Wilcoxconfig HAVE_ARCH_TRANSPARENT_HUGEPAGE_PUD 656a00cc7d9SMatthew Wilcox bool 657a00cc7d9SMatthew Wilcox 6580ddab1d2SToshi Kaniconfig HAVE_ARCH_HUGE_VMAP 6590ddab1d2SToshi Kani bool 6600ddab1d2SToshi Kani 6610f8975ecSPavel Emelyanovconfig HAVE_ARCH_SOFT_DIRTY 6620f8975ecSPavel Emelyanov bool 6630f8975ecSPavel Emelyanov 664786d35d4SDavid Howellsconfig HAVE_MOD_ARCH_SPECIFIC 665786d35d4SDavid Howells bool 666786d35d4SDavid Howells help 667786d35d4SDavid Howells The arch uses struct mod_arch_specific to store data. Many arches 668786d35d4SDavid Howells just need a simple module loader without arch specific data - those 669786d35d4SDavid Howells should not enable this. 670786d35d4SDavid Howells 671786d35d4SDavid Howellsconfig MODULES_USE_ELF_RELA 672786d35d4SDavid Howells bool 673786d35d4SDavid Howells help 674786d35d4SDavid Howells Modules only use ELF RELA relocations. Modules with ELF REL 675786d35d4SDavid Howells relocations will give an error. 676786d35d4SDavid Howells 677786d35d4SDavid Howellsconfig MODULES_USE_ELF_REL 678786d35d4SDavid Howells bool 679786d35d4SDavid Howells help 680786d35d4SDavid Howells Modules only use ELF REL relocations. Modules with ELF RELA 681786d35d4SDavid Howells relocations will give an error. 682786d35d4SDavid Howells 683b92021b0SRusty Russellconfig HAVE_UNDERSCORE_SYMBOL_PREFIX 684b92021b0SRusty Russell bool 685b92021b0SRusty Russell help 686b92021b0SRusty Russell Some architectures generate an _ in front of C symbols; things like 687b92021b0SRusty Russell module loading and assembly files need to know about this. 688b92021b0SRusty Russell 689cc1f0274SFrederic Weisbeckerconfig HAVE_IRQ_EXIT_ON_IRQ_STACK 690cc1f0274SFrederic Weisbecker bool 691cc1f0274SFrederic Weisbecker help 692cc1f0274SFrederic Weisbecker Architecture doesn't only execute the irq handler on the irq stack 693cc1f0274SFrederic Weisbecker but also irq_exit(). This way we can process softirqs on this irq 694cc1f0274SFrederic Weisbecker stack instead of switching to a new one when we call __do_softirq() 695cc1f0274SFrederic Weisbecker in the end of an hardirq. 696cc1f0274SFrederic Weisbecker This spares a stack switch and improves cache usage on softirq 697cc1f0274SFrederic Weisbecker processing. 698cc1f0274SFrederic Weisbecker 699235a8f02SKirill A. Shutemovconfig PGTABLE_LEVELS 700235a8f02SKirill A. Shutemov int 701235a8f02SKirill A. Shutemov default 2 702235a8f02SKirill A. Shutemov 7032b68f6caSKees Cookconfig ARCH_HAS_ELF_RANDOMIZE 7042b68f6caSKees Cook bool 7052b68f6caSKees Cook help 7062b68f6caSKees Cook An architecture supports choosing randomized locations for 7072b68f6caSKees Cook stack, mmap, brk, and ET_DYN. Defined functions: 7082b68f6caSKees Cook - arch_mmap_rnd() 709204db6edSKees Cook - arch_randomize_brk() 7102b68f6caSKees Cook 711d07e2259SDaniel Cashmanconfig HAVE_ARCH_MMAP_RND_BITS 712d07e2259SDaniel Cashman bool 713d07e2259SDaniel Cashman help 714d07e2259SDaniel Cashman An arch should select this symbol if it supports setting a variable 715d07e2259SDaniel Cashman number of bits for use in establishing the base address for mmap 716d07e2259SDaniel Cashman allocations, has MMU enabled and provides values for both: 717d07e2259SDaniel Cashman - ARCH_MMAP_RND_BITS_MIN 718d07e2259SDaniel Cashman - ARCH_MMAP_RND_BITS_MAX 719d07e2259SDaniel Cashman 7205f56a5dfSJiri Slabyconfig HAVE_EXIT_THREAD 7215f56a5dfSJiri Slaby bool 7225f56a5dfSJiri Slaby help 7235f56a5dfSJiri Slaby An architecture implements exit_thread. 7245f56a5dfSJiri Slaby 725d07e2259SDaniel Cashmanconfig ARCH_MMAP_RND_BITS_MIN 726d07e2259SDaniel Cashman int 727d07e2259SDaniel Cashman 728d07e2259SDaniel Cashmanconfig ARCH_MMAP_RND_BITS_MAX 729d07e2259SDaniel Cashman int 730d07e2259SDaniel Cashman 731d07e2259SDaniel Cashmanconfig ARCH_MMAP_RND_BITS_DEFAULT 732d07e2259SDaniel Cashman int 733d07e2259SDaniel Cashman 734d07e2259SDaniel Cashmanconfig ARCH_MMAP_RND_BITS 735d07e2259SDaniel Cashman int "Number of bits to use for ASLR of mmap base address" if EXPERT 736d07e2259SDaniel Cashman range ARCH_MMAP_RND_BITS_MIN ARCH_MMAP_RND_BITS_MAX 737d07e2259SDaniel Cashman default ARCH_MMAP_RND_BITS_DEFAULT if ARCH_MMAP_RND_BITS_DEFAULT 738d07e2259SDaniel Cashman default ARCH_MMAP_RND_BITS_MIN 739d07e2259SDaniel Cashman depends on HAVE_ARCH_MMAP_RND_BITS 740d07e2259SDaniel Cashman help 741d07e2259SDaniel Cashman This value can be used to select the number of bits to use to 742d07e2259SDaniel Cashman determine the random offset to the base address of vma regions 743d07e2259SDaniel Cashman resulting from mmap allocations. This value will be bounded 744d07e2259SDaniel Cashman by the architecture's minimum and maximum supported values. 745d07e2259SDaniel Cashman 746d07e2259SDaniel Cashman This value can be changed after boot using the 747d07e2259SDaniel Cashman /proc/sys/vm/mmap_rnd_bits tunable 748d07e2259SDaniel Cashman 749d07e2259SDaniel Cashmanconfig HAVE_ARCH_MMAP_RND_COMPAT_BITS 750d07e2259SDaniel Cashman bool 751d07e2259SDaniel Cashman help 752d07e2259SDaniel Cashman An arch should select this symbol if it supports running applications 753d07e2259SDaniel Cashman in compatibility mode, supports setting a variable number of bits for 754d07e2259SDaniel Cashman use in establishing the base address for mmap allocations, has MMU 755d07e2259SDaniel Cashman enabled and provides values for both: 756d07e2259SDaniel Cashman - ARCH_MMAP_RND_COMPAT_BITS_MIN 757d07e2259SDaniel Cashman - ARCH_MMAP_RND_COMPAT_BITS_MAX 758d07e2259SDaniel Cashman 759d07e2259SDaniel Cashmanconfig ARCH_MMAP_RND_COMPAT_BITS_MIN 760d07e2259SDaniel Cashman int 761d07e2259SDaniel Cashman 762d07e2259SDaniel Cashmanconfig ARCH_MMAP_RND_COMPAT_BITS_MAX 763d07e2259SDaniel Cashman int 764d07e2259SDaniel Cashman 765d07e2259SDaniel Cashmanconfig ARCH_MMAP_RND_COMPAT_BITS_DEFAULT 766d07e2259SDaniel Cashman int 767d07e2259SDaniel Cashman 768d07e2259SDaniel Cashmanconfig ARCH_MMAP_RND_COMPAT_BITS 769d07e2259SDaniel Cashman int "Number of bits to use for ASLR of mmap base address for compatible applications" if EXPERT 770d07e2259SDaniel Cashman range ARCH_MMAP_RND_COMPAT_BITS_MIN ARCH_MMAP_RND_COMPAT_BITS_MAX 771d07e2259SDaniel Cashman default ARCH_MMAP_RND_COMPAT_BITS_DEFAULT if ARCH_MMAP_RND_COMPAT_BITS_DEFAULT 772d07e2259SDaniel Cashman default ARCH_MMAP_RND_COMPAT_BITS_MIN 773d07e2259SDaniel Cashman depends on HAVE_ARCH_MMAP_RND_COMPAT_BITS 774d07e2259SDaniel Cashman help 775d07e2259SDaniel Cashman This value can be used to select the number of bits to use to 776d07e2259SDaniel Cashman determine the random offset to the base address of vma regions 777d07e2259SDaniel Cashman resulting from mmap allocations for compatible applications This 778d07e2259SDaniel Cashman value will be bounded by the architecture's minimum and maximum 779d07e2259SDaniel Cashman supported values. 780d07e2259SDaniel Cashman 781d07e2259SDaniel Cashman This value can be changed after boot using the 782d07e2259SDaniel Cashman /proc/sys/vm/mmap_rnd_compat_bits tunable 783d07e2259SDaniel Cashman 7841b028f78SDmitry Safonovconfig HAVE_ARCH_COMPAT_MMAP_BASES 7851b028f78SDmitry Safonov bool 7861b028f78SDmitry Safonov help 7871b028f78SDmitry Safonov This allows 64bit applications to invoke 32-bit mmap() syscall 7881b028f78SDmitry Safonov and vice-versa 32-bit applications to call 64-bit mmap(). 7891b028f78SDmitry Safonov Required for applications doing different bitness syscalls. 7901b028f78SDmitry Safonov 7913033f14aSJosh Triplettconfig HAVE_COPY_THREAD_TLS 7923033f14aSJosh Triplett bool 7933033f14aSJosh Triplett help 7943033f14aSJosh Triplett Architecture provides copy_thread_tls to accept tls argument via 7953033f14aSJosh Triplett normal C parameter passing, rather than extracting the syscall 7963033f14aSJosh Triplett argument from pt_regs. 7973033f14aSJosh Triplett 798b9ab5ebbSJosh Poimboeufconfig HAVE_STACK_VALIDATION 799b9ab5ebbSJosh Poimboeuf bool 800b9ab5ebbSJosh Poimboeuf help 801b9ab5ebbSJosh Poimboeuf Architecture supports the 'objtool check' host tool command, which 802b9ab5ebbSJosh Poimboeuf performs compile-time stack metadata validation. 803b9ab5ebbSJosh Poimboeuf 804af085d90SJosh Poimboeufconfig HAVE_RELIABLE_STACKTRACE 805af085d90SJosh Poimboeuf bool 806af085d90SJosh Poimboeuf help 807af085d90SJosh Poimboeuf Architecture has a save_stack_trace_tsk_reliable() function which 808af085d90SJosh Poimboeuf only returns a stack trace if it can guarantee the trace is reliable. 809af085d90SJosh Poimboeuf 810468a9428SGeorge Spelvinconfig HAVE_ARCH_HASH 811468a9428SGeorge Spelvin bool 812468a9428SGeorge Spelvin default n 813468a9428SGeorge Spelvin help 814468a9428SGeorge Spelvin If this is set, the architecture provides an <asm/hash.h> 815468a9428SGeorge Spelvin file which provides platform-specific implementations of some 816468a9428SGeorge Spelvin functions in <linux/hash.h> or fs/namei.c. 817468a9428SGeorge Spelvin 8183a495511SWilliam Breathitt Grayconfig ISA_BUS_API 8193a495511SWilliam Breathitt Gray def_bool ISA 8203a495511SWilliam Breathitt Gray 821d2125043SAl Viro# 822d2125043SAl Viro# ABI hall of shame 823d2125043SAl Viro# 824d2125043SAl Viroconfig CLONE_BACKWARDS 825d2125043SAl Viro bool 826d2125043SAl Viro help 827d2125043SAl Viro Architecture has tls passed as the 4th argument of clone(2), 828d2125043SAl Viro not the 5th one. 829d2125043SAl Viro 830d2125043SAl Viroconfig CLONE_BACKWARDS2 831d2125043SAl Viro bool 832d2125043SAl Viro help 833d2125043SAl Viro Architecture has the first two arguments of clone(2) swapped. 834d2125043SAl Viro 835dfa9771aSMichal Simekconfig CLONE_BACKWARDS3 836dfa9771aSMichal Simek bool 837dfa9771aSMichal Simek help 838dfa9771aSMichal Simek Architecture has tls passed as the 3rd argument of clone(2), 839dfa9771aSMichal Simek not the 5th one. 840dfa9771aSMichal Simek 841eaca6eaeSAl Viroconfig ODD_RT_SIGACTION 842eaca6eaeSAl Viro bool 843eaca6eaeSAl Viro help 844eaca6eaeSAl Viro Architecture has unusual rt_sigaction(2) arguments 845eaca6eaeSAl Viro 8460a0e8cdfSAl Viroconfig OLD_SIGSUSPEND 8470a0e8cdfSAl Viro bool 8480a0e8cdfSAl Viro help 8490a0e8cdfSAl Viro Architecture has old sigsuspend(2) syscall, of one-argument variety 8500a0e8cdfSAl Viro 8510a0e8cdfSAl Viroconfig OLD_SIGSUSPEND3 8520a0e8cdfSAl Viro bool 8530a0e8cdfSAl Viro help 8540a0e8cdfSAl Viro Even weirder antique ABI - three-argument sigsuspend(2) 8550a0e8cdfSAl Viro 856495dfbf7SAl Viroconfig OLD_SIGACTION 857495dfbf7SAl Viro bool 858495dfbf7SAl Viro help 859495dfbf7SAl Viro Architecture has old sigaction(2) syscall. Nope, not the same 860495dfbf7SAl Viro as OLD_SIGSUSPEND | OLD_SIGSUSPEND3 - alpha has sigsuspend(2), 861495dfbf7SAl Viro but fairly different variant of sigaction(2), thanks to OSF/1 862495dfbf7SAl Viro compatibility... 863495dfbf7SAl Viro 864495dfbf7SAl Viroconfig COMPAT_OLD_SIGACTION 865495dfbf7SAl Viro bool 866495dfbf7SAl Viro 8670d4a619bSChristoph Hellwigconfig ARCH_NO_COHERENT_DMA_MMAP 8680d4a619bSChristoph Hellwig bool 8690d4a619bSChristoph Hellwig 870fff7fb0bSZhaoxiu Zengconfig CPU_NO_EFFICIENT_FFS 871fff7fb0bSZhaoxiu Zeng def_bool n 872fff7fb0bSZhaoxiu Zeng 873ba14a194SAndy Lutomirskiconfig HAVE_ARCH_VMAP_STACK 874ba14a194SAndy Lutomirski def_bool n 875ba14a194SAndy Lutomirski help 876ba14a194SAndy Lutomirski An arch should select this symbol if it can support kernel stacks 877ba14a194SAndy Lutomirski in vmalloc space. This means: 878ba14a194SAndy Lutomirski 879ba14a194SAndy Lutomirski - vmalloc space must be large enough to hold many kernel stacks. 880ba14a194SAndy Lutomirski This may rule out many 32-bit architectures. 881ba14a194SAndy Lutomirski 882ba14a194SAndy Lutomirski - Stacks in vmalloc space need to work reliably. For example, if 883ba14a194SAndy Lutomirski vmap page tables are created on demand, either this mechanism 884ba14a194SAndy Lutomirski needs to work while the stack points to a virtual address with 885ba14a194SAndy Lutomirski unpopulated page tables or arch code (switch_to() and switch_mm(), 886ba14a194SAndy Lutomirski most likely) needs to ensure that the stack's page table entries 887ba14a194SAndy Lutomirski are populated before running on a possibly unpopulated stack. 888ba14a194SAndy Lutomirski 889ba14a194SAndy Lutomirski - If the stack overflows into a guard page, something reasonable 890ba14a194SAndy Lutomirski should happen. The definition of "reasonable" is flexible, but 891ba14a194SAndy Lutomirski instantly rebooting without logging anything would be unfriendly. 892ba14a194SAndy Lutomirski 893ba14a194SAndy Lutomirskiconfig VMAP_STACK 894ba14a194SAndy Lutomirski default y 895ba14a194SAndy Lutomirski bool "Use a virtually-mapped stack" 896ba14a194SAndy Lutomirski depends on HAVE_ARCH_VMAP_STACK && !KASAN 897ba14a194SAndy Lutomirski ---help--- 898ba14a194SAndy Lutomirski Enable this if you want the use virtually-mapped kernel stacks 899ba14a194SAndy Lutomirski with guard pages. This causes kernel stack overflows to be 900ba14a194SAndy Lutomirski caught immediately rather than causing difficult-to-diagnose 901ba14a194SAndy Lutomirski corruption. 902ba14a194SAndy Lutomirski 903ba14a194SAndy Lutomirski This is presently incompatible with KASAN because KASAN expects 904ba14a194SAndy Lutomirski the stack to map directly to the KASAN shadow map using a formula 905ba14a194SAndy Lutomirski that is incorrect if the stack is in vmalloc space. 906ba14a194SAndy Lutomirski 907ad21fc4fSLaura Abbottconfig ARCH_OPTIONAL_KERNEL_RWX 908ad21fc4fSLaura Abbott def_bool n 909ad21fc4fSLaura Abbott 910ad21fc4fSLaura Abbottconfig ARCH_OPTIONAL_KERNEL_RWX_DEFAULT 911ad21fc4fSLaura Abbott def_bool n 912ad21fc4fSLaura Abbott 913ad21fc4fSLaura Abbottconfig ARCH_HAS_STRICT_KERNEL_RWX 914ad21fc4fSLaura Abbott def_bool n 915ad21fc4fSLaura Abbott 9160f5bf6d0SLaura Abbottconfig STRICT_KERNEL_RWX 917ad21fc4fSLaura Abbott bool "Make kernel text and rodata read-only" if ARCH_OPTIONAL_KERNEL_RWX 918ad21fc4fSLaura Abbott depends on ARCH_HAS_STRICT_KERNEL_RWX 919ad21fc4fSLaura Abbott default !ARCH_OPTIONAL_KERNEL_RWX || ARCH_OPTIONAL_KERNEL_RWX_DEFAULT 920ad21fc4fSLaura Abbott help 921ad21fc4fSLaura Abbott If this is set, kernel text and rodata memory will be made read-only, 922ad21fc4fSLaura Abbott and non-text memory will be made non-executable. This provides 923ad21fc4fSLaura Abbott protection against certain security exploits (e.g. executing the heap 924ad21fc4fSLaura Abbott or modifying text) 925ad21fc4fSLaura Abbott 926ad21fc4fSLaura Abbott These features are considered standard security practice these days. 927ad21fc4fSLaura Abbott You should say Y here in almost all cases. 928ad21fc4fSLaura Abbott 929ad21fc4fSLaura Abbottconfig ARCH_HAS_STRICT_MODULE_RWX 930ad21fc4fSLaura Abbott def_bool n 931ad21fc4fSLaura Abbott 9320f5bf6d0SLaura Abbottconfig STRICT_MODULE_RWX 933ad21fc4fSLaura Abbott bool "Set loadable kernel module data as NX and text as RO" if ARCH_OPTIONAL_KERNEL_RWX 934ad21fc4fSLaura Abbott depends on ARCH_HAS_STRICT_MODULE_RWX && MODULES 935ad21fc4fSLaura Abbott default !ARCH_OPTIONAL_KERNEL_RWX || ARCH_OPTIONAL_KERNEL_RWX_DEFAULT 936ad21fc4fSLaura Abbott help 937ad21fc4fSLaura Abbott If this is set, module text and rodata memory will be made read-only, 938ad21fc4fSLaura Abbott and non-text memory will be made non-executable. This provides 939ad21fc4fSLaura Abbott protection against certain security exploits (e.g. writing to text) 940ad21fc4fSLaura Abbott 941ea8c64acSChristoph Hellwig# select if the architecture provides an asm/dma-direct.h header 942ea8c64acSChristoph Hellwigconfig ARCH_HAS_PHYS_TO_DMA 943ea8c64acSChristoph Hellwig bool 944ea8c64acSChristoph Hellwig 9457a46ec0eSKees Cookconfig ARCH_HAS_REFCOUNT 9467a46ec0eSKees Cook bool 9477a46ec0eSKees Cook help 9487a46ec0eSKees Cook An architecture selects this when it has implemented refcount_t 9497a46ec0eSKees Cook using open coded assembly primitives that provide an optimized 9507a46ec0eSKees Cook refcount_t implementation, possibly at the expense of some full 9517a46ec0eSKees Cook refcount state checks of CONFIG_REFCOUNT_FULL=y. 9527a46ec0eSKees Cook 9537a46ec0eSKees Cook The refcount overflow check behavior, however, must be retained. 9547a46ec0eSKees Cook Catching overflows is the primary security concern for protecting 9557a46ec0eSKees Cook against bugs in reference counts. 9567a46ec0eSKees Cook 957fd25d19fSKees Cookconfig REFCOUNT_FULL 958fd25d19fSKees Cook bool "Perform full reference count validation at the expense of speed" 959fd25d19fSKees Cook help 960fd25d19fSKees Cook Enabling this switches the refcounting infrastructure from a fast 961fd25d19fSKees Cook unchecked atomic_t implementation to a fully state checked 962fd25d19fSKees Cook implementation, which can be (slightly) slower but provides protections 963fd25d19fSKees Cook against various use-after-free conditions that can be used in 964fd25d19fSKees Cook security flaw exploits. 965fd25d19fSKees Cook 9662521f2c2SPeter Oberparleitersource "kernel/gcov/Kconfig" 967