1fb32e03fSMathieu Desnoyers# 2fb32e03fSMathieu Desnoyers# General architecture dependent options 3fb32e03fSMathieu Desnoyers# 4125e5645SMathieu Desnoyers 5692f66f2SHari Bathiniconfig CRASH_CORE 6692f66f2SHari Bathini bool 7692f66f2SHari Bathini 82965faa5SDave Youngconfig KEXEC_CORE 9692f66f2SHari Bathini select CRASH_CORE 102965faa5SDave Young bool 112965faa5SDave Young 12467d2782SThiago Jung Bauermannconfig HAVE_IMA_KEXEC 13467d2782SThiago Jung Bauermann bool 14467d2782SThiago Jung Bauermann 15125e5645SMathieu Desnoyersconfig OPROFILE 16b309a294SRobert Richter tristate "OProfile system profiling" 17125e5645SMathieu Desnoyers depends on PROFILING 18125e5645SMathieu Desnoyers depends on HAVE_OPROFILE 19d69d59f4SIngo Molnar select RING_BUFFER 209a5963ebSChristian Borntraeger select RING_BUFFER_ALLOW_SWAP 21125e5645SMathieu Desnoyers help 22125e5645SMathieu Desnoyers OProfile is a profiling system capable of profiling the 23125e5645SMathieu Desnoyers whole system, include the kernel, kernel modules, libraries, 24125e5645SMathieu Desnoyers and applications. 25125e5645SMathieu Desnoyers 26125e5645SMathieu Desnoyers If unsure, say N. 27125e5645SMathieu Desnoyers 284d4036e0SJason Yehconfig OPROFILE_EVENT_MULTIPLEX 294d4036e0SJason Yeh bool "OProfile multiplexing support (EXPERIMENTAL)" 304d4036e0SJason Yeh default n 314d4036e0SJason Yeh depends on OPROFILE && X86 324d4036e0SJason Yeh help 334d4036e0SJason Yeh The number of hardware counters is limited. The multiplexing 344d4036e0SJason Yeh feature enables OProfile to gather more events than counters 354d4036e0SJason Yeh are provided by the hardware. This is realized by switching 369332ef9dSMasahiro Yamada between events at a user specified time interval. 374d4036e0SJason Yeh 384d4036e0SJason Yeh If unsure, say N. 394d4036e0SJason Yeh 40125e5645SMathieu Desnoyersconfig HAVE_OPROFILE 419ba16087SJan Beulich bool 42125e5645SMathieu Desnoyers 43dcfce4a0SRobert Richterconfig OPROFILE_NMI_TIMER 44dcfce4a0SRobert Richter def_bool y 45af9feebeSAnton Blanchard depends on PERF_EVENTS && HAVE_PERF_EVENTS_NMI && !PPC64 46dcfce4a0SRobert Richter 47125e5645SMathieu Desnoyersconfig KPROBES 48125e5645SMathieu Desnoyers bool "Kprobes" 4905ed160eSMasami Hiramatsu depends on MODULES 50125e5645SMathieu Desnoyers depends on HAVE_KPROBES 5105ed160eSMasami Hiramatsu select KALLSYMS 52125e5645SMathieu Desnoyers help 53125e5645SMathieu Desnoyers Kprobes allows you to trap at almost any kernel address and 54125e5645SMathieu Desnoyers execute a callback function. register_kprobe() establishes 55125e5645SMathieu Desnoyers a probepoint and specifies the callback. Kprobes is useful 56125e5645SMathieu Desnoyers for kernel debugging, non-intrusive instrumentation and testing. 57125e5645SMathieu Desnoyers If in doubt, say "N". 58125e5645SMathieu Desnoyers 5945f81b1cSSteven Rostedtconfig JUMP_LABEL 60c5905afbSIngo Molnar bool "Optimize very unlikely/likely branches" 6145f81b1cSSteven Rostedt depends on HAVE_ARCH_JUMP_LABEL 6245f81b1cSSteven Rostedt help 63c5905afbSIngo Molnar This option enables a transparent branch optimization that 64c5905afbSIngo Molnar makes certain almost-always-true or almost-always-false branch 65c5905afbSIngo Molnar conditions even cheaper to execute within the kernel. 6645f81b1cSSteven Rostedt 67c5905afbSIngo Molnar Certain performance-sensitive kernel code, such as trace points, 68c5905afbSIngo Molnar scheduler functionality, networking code and KVM have such 69c5905afbSIngo Molnar branches and include support for this optimization technique. 70c5905afbSIngo Molnar 71c5905afbSIngo Molnar If it is detected that the compiler has support for "asm goto", 72c5905afbSIngo Molnar the kernel will compile such branches with just a nop 73c5905afbSIngo Molnar instruction. When the condition flag is toggled to true, the 74c5905afbSIngo Molnar nop will be converted to a jump instruction to execute the 75c5905afbSIngo Molnar conditional block of instructions. 76c5905afbSIngo Molnar 77c5905afbSIngo Molnar This technique lowers overhead and stress on the branch prediction 78c5905afbSIngo Molnar of the processor and generally makes the kernel faster. The update 79c5905afbSIngo Molnar of the condition is slower, but those are always very rare. 80c5905afbSIngo Molnar 81c5905afbSIngo Molnar ( On 32-bit x86, the necessary options added to the compiler 82c5905afbSIngo Molnar flags may increase the size of the kernel slightly. ) 8345f81b1cSSteven Rostedt 841987c947SPeter Zijlstraconfig STATIC_KEYS_SELFTEST 851987c947SPeter Zijlstra bool "Static key selftest" 861987c947SPeter Zijlstra depends on JUMP_LABEL 871987c947SPeter Zijlstra help 881987c947SPeter Zijlstra Boot time self-test of the branch patching code. 891987c947SPeter Zijlstra 90afd66255SMasami Hiramatsuconfig OPTPROBES 915cc718b9SMasami Hiramatsu def_bool y 925cc718b9SMasami Hiramatsu depends on KPROBES && HAVE_OPTPROBES 93afd66255SMasami Hiramatsu depends on !PREEMPT 94afd66255SMasami Hiramatsu 95e7dbfe34SMasami Hiramatsuconfig KPROBES_ON_FTRACE 96e7dbfe34SMasami Hiramatsu def_bool y 97e7dbfe34SMasami Hiramatsu depends on KPROBES && HAVE_KPROBES_ON_FTRACE 98e7dbfe34SMasami Hiramatsu depends on DYNAMIC_FTRACE_WITH_REGS 99e7dbfe34SMasami Hiramatsu help 100e7dbfe34SMasami Hiramatsu If function tracer is enabled and the arch supports full 101e7dbfe34SMasami Hiramatsu passing of pt_regs to function tracing, then kprobes can 102e7dbfe34SMasami Hiramatsu optimize on top of function tracing. 103e7dbfe34SMasami Hiramatsu 1042b144498SSrikar Dronamrajuconfig UPROBES 10509294e31SDavid A. Long def_bool n 106e8f4aa60SAllen Pais depends on ARCH_SUPPORTS_UPROBES 1072b144498SSrikar Dronamraju help 1087b2d81d4SIngo Molnar Uprobes is the user-space counterpart to kprobes: they 1097b2d81d4SIngo Molnar enable instrumentation applications (such as 'perf probe') 1107b2d81d4SIngo Molnar to establish unintrusive probes in user-space binaries and 1117b2d81d4SIngo Molnar libraries, by executing handler functions when the probes 1127b2d81d4SIngo Molnar are hit by user-space applications. 1137b2d81d4SIngo Molnar 1147b2d81d4SIngo Molnar ( These probes come in the form of single-byte breakpoints, 1157b2d81d4SIngo Molnar managed by the kernel and kept transparent to the probed 1167b2d81d4SIngo Molnar application. ) 1172b144498SSrikar Dronamraju 118c19fa94aSJames Hoganconfig HAVE_64BIT_ALIGNED_ACCESS 119c19fa94aSJames Hogan def_bool 64BIT && !HAVE_EFFICIENT_UNALIGNED_ACCESS 120c19fa94aSJames Hogan help 121c19fa94aSJames Hogan Some architectures require 64 bit accesses to be 64 bit 122c19fa94aSJames Hogan aligned, which also requires structs containing 64 bit values 123c19fa94aSJames Hogan to be 64 bit aligned too. This includes some 32 bit 124c19fa94aSJames Hogan architectures which can do 64 bit accesses, as well as 64 bit 125c19fa94aSJames Hogan architectures without unaligned access. 126c19fa94aSJames Hogan 127c19fa94aSJames Hogan This symbol should be selected by an architecture if 64 bit 128c19fa94aSJames Hogan accesses are required to be 64 bit aligned in this way even 129c19fa94aSJames Hogan though it is not a 64 bit architecture. 130c19fa94aSJames Hogan 131c19fa94aSJames Hogan See Documentation/unaligned-memory-access.txt for more 132c19fa94aSJames Hogan information on the topic of unaligned memory accesses. 133c19fa94aSJames Hogan 13458340a07SJohannes Bergconfig HAVE_EFFICIENT_UNALIGNED_ACCESS 1359ba16087SJan Beulich bool 13658340a07SJohannes Berg help 13758340a07SJohannes Berg Some architectures are unable to perform unaligned accesses 13858340a07SJohannes Berg without the use of get_unaligned/put_unaligned. Others are 13958340a07SJohannes Berg unable to perform such accesses efficiently (e.g. trap on 14058340a07SJohannes Berg unaligned access and require fixing it up in the exception 14158340a07SJohannes Berg handler.) 14258340a07SJohannes Berg 14358340a07SJohannes Berg This symbol should be selected by an architecture if it can 14458340a07SJohannes Berg perform unaligned accesses efficiently to allow different 14558340a07SJohannes Berg code paths to be selected for these cases. Some network 14658340a07SJohannes Berg drivers, for example, could opt to not fix up alignment 14758340a07SJohannes Berg problems with received packets if doing so would not help 14858340a07SJohannes Berg much. 14958340a07SJohannes Berg 15058340a07SJohannes Berg See Documentation/unaligned-memory-access.txt for more 15158340a07SJohannes Berg information on the topic of unaligned memory accesses. 15258340a07SJohannes Berg 153cf66bb93SDavid Woodhouseconfig ARCH_USE_BUILTIN_BSWAP 154cf66bb93SDavid Woodhouse bool 155cf66bb93SDavid Woodhouse help 156cf66bb93SDavid Woodhouse Modern versions of GCC (since 4.4) have builtin functions 157cf66bb93SDavid Woodhouse for handling byte-swapping. Using these, instead of the old 158cf66bb93SDavid Woodhouse inline assembler that the architecture code provides in the 159cf66bb93SDavid Woodhouse __arch_bswapXX() macros, allows the compiler to see what's 160cf66bb93SDavid Woodhouse happening and offers more opportunity for optimisation. In 161cf66bb93SDavid Woodhouse particular, the compiler will be able to combine the byteswap 162cf66bb93SDavid Woodhouse with a nearby load or store and use load-and-swap or 163cf66bb93SDavid Woodhouse store-and-swap instructions if the architecture has them. It 164cf66bb93SDavid Woodhouse should almost *never* result in code which is worse than the 165cf66bb93SDavid Woodhouse hand-coded assembler in <asm/swab.h>. But just in case it 166cf66bb93SDavid Woodhouse does, the use of the builtins is optional. 167cf66bb93SDavid Woodhouse 168cf66bb93SDavid Woodhouse Any architecture with load-and-swap or store-and-swap 169cf66bb93SDavid Woodhouse instructions should set this. And it shouldn't hurt to set it 170cf66bb93SDavid Woodhouse on architectures that don't have such instructions. 171cf66bb93SDavid Woodhouse 1729edddaa2SAnanth N Mavinakayanahalliconfig KRETPROBES 1739edddaa2SAnanth N Mavinakayanahalli def_bool y 1749edddaa2SAnanth N Mavinakayanahalli depends on KPROBES && HAVE_KRETPROBES 1759edddaa2SAnanth N Mavinakayanahalli 1767c68af6eSAvi Kivityconfig USER_RETURN_NOTIFIER 1777c68af6eSAvi Kivity bool 1787c68af6eSAvi Kivity depends on HAVE_USER_RETURN_NOTIFIER 1797c68af6eSAvi Kivity help 1807c68af6eSAvi Kivity Provide a kernel-internal notification when a cpu is about to 1817c68af6eSAvi Kivity switch to user mode. 1827c68af6eSAvi Kivity 18328b2ee20SRik van Rielconfig HAVE_IOREMAP_PROT 1849ba16087SJan Beulich bool 18528b2ee20SRik van Riel 186125e5645SMathieu Desnoyersconfig HAVE_KPROBES 1879ba16087SJan Beulich bool 1889edddaa2SAnanth N Mavinakayanahalli 1899edddaa2SAnanth N Mavinakayanahalliconfig HAVE_KRETPROBES 1909ba16087SJan Beulich bool 19174bc7ceeSArthur Kepner 192afd66255SMasami Hiramatsuconfig HAVE_OPTPROBES 193afd66255SMasami Hiramatsu bool 194d314d74cSCong Wang 195e7dbfe34SMasami Hiramatsuconfig HAVE_KPROBES_ON_FTRACE 196e7dbfe34SMasami Hiramatsu bool 197e7dbfe34SMasami Hiramatsu 19842a0bb3fSPetr Mladekconfig HAVE_NMI 19942a0bb3fSPetr Mladek bool 20042a0bb3fSPetr Mladek 201d314d74cSCong Wangconfig HAVE_NMI_WATCHDOG 20242a0bb3fSPetr Mladek depends on HAVE_NMI 203d314d74cSCong Wang bool 2041f5a4ad9SRoland McGrath# 2051f5a4ad9SRoland McGrath# An arch should select this if it provides all these things: 2061f5a4ad9SRoland McGrath# 2071f5a4ad9SRoland McGrath# task_pt_regs() in asm/processor.h or asm/ptrace.h 2081f5a4ad9SRoland McGrath# arch_has_single_step() if there is hardware single-step support 2091f5a4ad9SRoland McGrath# arch_has_block_step() if there is hardware block-step support 2101f5a4ad9SRoland McGrath# asm/syscall.h supplying asm-generic/syscall.h interface 2111f5a4ad9SRoland McGrath# linux/regset.h user_regset interfaces 2121f5a4ad9SRoland McGrath# CORE_DUMP_USE_REGSET #define'd in linux/elf.h 2131f5a4ad9SRoland McGrath# TIF_SYSCALL_TRACE calls tracehook_report_syscall_{entry,exit} 2141f5a4ad9SRoland McGrath# TIF_NOTIFY_RESUME calls tracehook_notify_resume() 2151f5a4ad9SRoland McGrath# signal delivery calls tracehook_signal_handler() 2161f5a4ad9SRoland McGrath# 2171f5a4ad9SRoland McGrathconfig HAVE_ARCH_TRACEHOOK 2189ba16087SJan Beulich bool 2191f5a4ad9SRoland McGrath 220c64be2bbSMarek Szyprowskiconfig HAVE_DMA_CONTIGUOUS 221c64be2bbSMarek Szyprowski bool 222c64be2bbSMarek Szyprowski 22329d5e047SThomas Gleixnerconfig GENERIC_SMP_IDLE_THREAD 22429d5e047SThomas Gleixner bool 22529d5e047SThomas Gleixner 226485cf5daSKevin Hilmanconfig GENERIC_IDLE_POLL_SETUP 227485cf5daSKevin Hilman bool 228485cf5daSKevin Hilman 229d2852a22SDaniel Borkmann# Select if arch has all set_memory_ro/rw/x/nx() functions in asm/cacheflush.h 230d2852a22SDaniel Borkmannconfig ARCH_HAS_SET_MEMORY 231d2852a22SDaniel Borkmann bool 232d2852a22SDaniel Borkmann 233a6359d1eSThomas Gleixner# Select if arch init_task initializer is different to init/init_task.c 234a6359d1eSThomas Gleixnerconfig ARCH_INIT_TASK 235a4a2eb49SThomas Gleixner bool 236a4a2eb49SThomas Gleixner 237f5e10287SThomas Gleixner# Select if arch has its private alloc_task_struct() function 238f5e10287SThomas Gleixnerconfig ARCH_TASK_STRUCT_ALLOCATOR 239f5e10287SThomas Gleixner bool 240f5e10287SThomas Gleixner 241b235beeaSLinus Torvalds# Select if arch has its private alloc_thread_stack() function 242b235beeaSLinus Torvaldsconfig ARCH_THREAD_STACK_ALLOCATOR 243f5e10287SThomas Gleixner bool 244f5e10287SThomas Gleixner 2455aaeb5c0SIngo Molnar# Select if arch wants to size task_struct dynamically via arch_task_struct_size: 2465aaeb5c0SIngo Molnarconfig ARCH_WANTS_DYNAMIC_TASK_STRUCT 2475aaeb5c0SIngo Molnar bool 2485aaeb5c0SIngo Molnar 249f850c30cSHeiko Carstensconfig HAVE_REGS_AND_STACK_ACCESS_API 250f850c30cSHeiko Carstens bool 251e01292b1SHeiko Carstens help 252e01292b1SHeiko Carstens This symbol should be selected by an architecure if it supports 253e01292b1SHeiko Carstens the API needed to access registers and stack entries from pt_regs, 254e01292b1SHeiko Carstens declared in asm/ptrace.h 255e01292b1SHeiko Carstens For example the kprobes-based event tracer needs this API. 256f850c30cSHeiko Carstens 2579483a578SDavid Brownellconfig HAVE_CLK 2589ba16087SJan Beulich bool 2599483a578SDavid Brownell help 2609483a578SDavid Brownell The <linux/clk.h> calls support software clock gating and 2619483a578SDavid Brownell thus are a key power management tool on many systems. 2629483a578SDavid Brownell 2635ee00bd4SJoerg Roedelconfig HAVE_DMA_API_DEBUG 2645ee00bd4SJoerg Roedel bool 26536cd3c9fSHeiko Carstens 26662a038d3SK.Prasadconfig HAVE_HW_BREAKPOINT 26762a038d3SK.Prasad bool 26899e8c5a3SFrederic Weisbecker depends on PERF_EVENTS 26962a038d3SK.Prasad 2700102752eSFrederic Weisbeckerconfig HAVE_MIXED_BREAKPOINTS_REGS 2710102752eSFrederic Weisbecker bool 2720102752eSFrederic Weisbecker depends on HAVE_HW_BREAKPOINT 2730102752eSFrederic Weisbecker help 2740102752eSFrederic Weisbecker Depending on the arch implementation of hardware breakpoints, 2750102752eSFrederic Weisbecker some of them have separate registers for data and instruction 2760102752eSFrederic Weisbecker breakpoints addresses, others have mixed registers to store 2770102752eSFrederic Weisbecker them but define the access type in a control register. 2780102752eSFrederic Weisbecker Select this option if your arch implements breakpoints under the 2790102752eSFrederic Weisbecker latter fashion. 2800102752eSFrederic Weisbecker 2817c68af6eSAvi Kivityconfig HAVE_USER_RETURN_NOTIFIER 2827c68af6eSAvi Kivity bool 283a1922ed6SIngo Molnar 284c01d4323SFrederic Weisbeckerconfig HAVE_PERF_EVENTS_NMI 285c01d4323SFrederic Weisbecker bool 28623637d47SFrederic Weisbecker help 28723637d47SFrederic Weisbecker System hardware can generate an NMI using the perf event 28823637d47SFrederic Weisbecker subsystem. Also has support for calculating CPU cycle events 28923637d47SFrederic Weisbecker to determine how many clock cycles in a given period. 290c01d4323SFrederic Weisbecker 291c5e63197SJiri Olsaconfig HAVE_PERF_REGS 292c5e63197SJiri Olsa bool 293c5e63197SJiri Olsa help 294c5e63197SJiri Olsa Support selective register dumps for perf events. This includes 295c5e63197SJiri Olsa bit-mapping of each registers and a unique architecture id. 296c5e63197SJiri Olsa 297c5ebcedbSJiri Olsaconfig HAVE_PERF_USER_STACK_DUMP 298c5ebcedbSJiri Olsa bool 299c5ebcedbSJiri Olsa help 300c5ebcedbSJiri Olsa Support user stack dumps for perf event samples. This needs 301c5ebcedbSJiri Olsa access to the user stack pointer which is not unified across 302c5ebcedbSJiri Olsa architectures. 303c5ebcedbSJiri Olsa 304bf5438fcSJason Baronconfig HAVE_ARCH_JUMP_LABEL 305bf5438fcSJason Baron bool 306bf5438fcSJason Baron 30726723911SPeter Zijlstraconfig HAVE_RCU_TABLE_FREE 30826723911SPeter Zijlstra bool 30926723911SPeter Zijlstra 310df013ffbSHuang Yingconfig ARCH_HAVE_NMI_SAFE_CMPXCHG 311df013ffbSHuang Ying bool 312df013ffbSHuang Ying 31343570fd2SHeiko Carstensconfig HAVE_ALIGNED_STRUCT_PAGE 31443570fd2SHeiko Carstens bool 31543570fd2SHeiko Carstens help 31643570fd2SHeiko Carstens This makes sure that struct pages are double word aligned and that 31743570fd2SHeiko Carstens e.g. the SLUB allocator can perform double word atomic operations 31843570fd2SHeiko Carstens on a struct page for better performance. However selecting this 31943570fd2SHeiko Carstens might increase the size of a struct page by a word. 32043570fd2SHeiko Carstens 3214156153cSHeiko Carstensconfig HAVE_CMPXCHG_LOCAL 3224156153cSHeiko Carstens bool 3234156153cSHeiko Carstens 3242565409fSHeiko Carstensconfig HAVE_CMPXCHG_DOUBLE 3252565409fSHeiko Carstens bool 3262565409fSHeiko Carstens 327c1d7e01dSWill Deaconconfig ARCH_WANT_IPC_PARSE_VERSION 328c1d7e01dSWill Deacon bool 329c1d7e01dSWill Deacon 330c1d7e01dSWill Deaconconfig ARCH_WANT_COMPAT_IPC_PARSE_VERSION 331c1d7e01dSWill Deacon bool 332c1d7e01dSWill Deacon 33348b25c43SChris Metcalfconfig ARCH_WANT_OLD_COMPAT_IPC 334c1d7e01dSWill Deacon select ARCH_WANT_COMPAT_IPC_PARSE_VERSION 33548b25c43SChris Metcalf bool 33648b25c43SChris Metcalf 337e2cfabdfSWill Drewryconfig HAVE_ARCH_SECCOMP_FILTER 338e2cfabdfSWill Drewry bool 339e2cfabdfSWill Drewry help 340fb0fadf9SWill Drewry An arch should select this symbol if it provides all of these things: 341bb6ea430SWill Drewry - syscall_get_arch() 342bb6ea430SWill Drewry - syscall_get_arguments() 343bb6ea430SWill Drewry - syscall_rollback() 344bb6ea430SWill Drewry - syscall_set_return_value() 345fb0fadf9SWill Drewry - SIGSYS siginfo_t support 346fb0fadf9SWill Drewry - secure_computing is called from a ptrace_event()-safe context 347fb0fadf9SWill Drewry - secure_computing return value is checked and a return value of -1 348fb0fadf9SWill Drewry results in the system call being skipped immediately. 34948dc92b9SKees Cook - seccomp syscall wired up 350e2cfabdfSWill Drewry 351e2cfabdfSWill Drewryconfig SECCOMP_FILTER 352e2cfabdfSWill Drewry def_bool y 353e2cfabdfSWill Drewry depends on HAVE_ARCH_SECCOMP_FILTER && SECCOMP && NET 354e2cfabdfSWill Drewry help 355e2cfabdfSWill Drewry Enable tasks to build secure computing environments defined 356e2cfabdfSWill Drewry in terms of Berkeley Packet Filter programs which implement 357e2cfabdfSWill Drewry task-defined system call filtering polices. 358e2cfabdfSWill Drewry 359e2cfabdfSWill Drewry See Documentation/prctl/seccomp_filter.txt for details. 360e2cfabdfSWill Drewry 3616b90bd4bSEmese Revfyconfig HAVE_GCC_PLUGINS 3626b90bd4bSEmese Revfy bool 3636b90bd4bSEmese Revfy help 3646b90bd4bSEmese Revfy An arch should select this symbol if it supports building with 3656b90bd4bSEmese Revfy GCC plugins. 3666b90bd4bSEmese Revfy 3676b90bd4bSEmese Revfymenuconfig GCC_PLUGINS 3686b90bd4bSEmese Revfy bool "GCC plugins" 3696b90bd4bSEmese Revfy depends on HAVE_GCC_PLUGINS 370a519167eSKees Cook depends on !COMPILE_TEST 3716b90bd4bSEmese Revfy help 3726b90bd4bSEmese Revfy GCC plugins are loadable modules that provide extra features to the 3736b90bd4bSEmese Revfy compiler. They are useful for runtime instrumentation and static analysis. 3746b90bd4bSEmese Revfy 3756b90bd4bSEmese Revfy See Documentation/gcc-plugins.txt for details. 3766b90bd4bSEmese Revfy 3770dae776cSEmese Revfyconfig GCC_PLUGIN_CYC_COMPLEXITY 378215e2aa6SKees Cook bool "Compute the cyclomatic complexity of a function" if EXPERT 3790dae776cSEmese Revfy depends on GCC_PLUGINS 380215e2aa6SKees Cook depends on !COMPILE_TEST 3810dae776cSEmese Revfy help 3820dae776cSEmese Revfy The complexity M of a function's control flow graph is defined as: 3830dae776cSEmese Revfy M = E - N + 2P 3840dae776cSEmese Revfy where 3850dae776cSEmese Revfy 3860dae776cSEmese Revfy E = the number of edges 3870dae776cSEmese Revfy N = the number of nodes 3880dae776cSEmese Revfy P = the number of connected components (exit nodes). 3890dae776cSEmese Revfy 390215e2aa6SKees Cook Enabling this plugin reports the complexity to stderr during the 391215e2aa6SKees Cook build. It mainly serves as a simple example of how to create a 392215e2aa6SKees Cook gcc plugin for the kernel. 393215e2aa6SKees Cook 394543c37cbSEmese Revfyconfig GCC_PLUGIN_SANCOV 395543c37cbSEmese Revfy bool 396543c37cbSEmese Revfy depends on GCC_PLUGINS 397543c37cbSEmese Revfy help 398543c37cbSEmese Revfy This plugin inserts a __sanitizer_cov_trace_pc() call at the start of 399543c37cbSEmese Revfy basic blocks. It supports all gcc versions with plugin support (from 400543c37cbSEmese Revfy gcc-4.5 on). It is based on the commit "Add fuzzing coverage support" 401543c37cbSEmese Revfy by Dmitry Vyukov <dvyukov@google.com>. 402543c37cbSEmese Revfy 40338addce8SEmese Revfyconfig GCC_PLUGIN_LATENT_ENTROPY 40438addce8SEmese Revfy bool "Generate some entropy during boot and runtime" 40538addce8SEmese Revfy depends on GCC_PLUGINS 40638addce8SEmese Revfy help 40738addce8SEmese Revfy By saying Y here the kernel will instrument some kernel code to 40838addce8SEmese Revfy extract some entropy from both original and artificially created 40938addce8SEmese Revfy program state. This will help especially embedded systems where 41038addce8SEmese Revfy there is little 'natural' source of entropy normally. The cost 41138addce8SEmese Revfy is some slowdown of the boot process (about 0.5%) and fork and 41238addce8SEmese Revfy irq processing. 41338addce8SEmese Revfy 41438addce8SEmese Revfy Note that entropy extracted this way is not cryptographically 41538addce8SEmese Revfy secure! 41638addce8SEmese Revfy 41738addce8SEmese Revfy This plugin was ported from grsecurity/PaX. More information at: 41838addce8SEmese Revfy * https://grsecurity.net/ 41938addce8SEmese Revfy * https://pax.grsecurity.net/ 42038addce8SEmese Revfy 421c61f13eaSKees Cookconfig GCC_PLUGIN_STRUCTLEAK 422c61f13eaSKees Cook bool "Force initialization of variables containing userspace addresses" 423c61f13eaSKees Cook depends on GCC_PLUGINS 424c61f13eaSKees Cook help 425c61f13eaSKees Cook This plugin zero-initializes any structures that containing a 426c61f13eaSKees Cook __user attribute. This can prevent some classes of information 427c61f13eaSKees Cook exposures. 428c61f13eaSKees Cook 429c61f13eaSKees Cook This plugin was ported from grsecurity/PaX. More information at: 430c61f13eaSKees Cook * https://grsecurity.net/ 431c61f13eaSKees Cook * https://pax.grsecurity.net/ 432c61f13eaSKees Cook 433c61f13eaSKees Cookconfig GCC_PLUGIN_STRUCTLEAK_VERBOSE 434c61f13eaSKees Cook bool "Report forcefully initialized variables" 435c61f13eaSKees Cook depends on GCC_PLUGIN_STRUCTLEAK 436c61f13eaSKees Cook depends on !COMPILE_TEST 437c61f13eaSKees Cook help 438c61f13eaSKees Cook This option will cause a warning to be printed each time the 439c61f13eaSKees Cook structleak plugin finds a variable it thinks needs to be 440c61f13eaSKees Cook initialized. Since not all existing initializers are detected 441c61f13eaSKees Cook by the plugin, this can produce false positive warnings. 442c61f13eaSKees Cook 44319952a92SKees Cookconfig HAVE_CC_STACKPROTECTOR 44419952a92SKees Cook bool 44519952a92SKees Cook help 44619952a92SKees Cook An arch should select this symbol if: 44719952a92SKees Cook - its compiler supports the -fstack-protector option 44819952a92SKees Cook - it has implemented a stack canary (e.g. __stack_chk_guard) 44919952a92SKees Cook 45019952a92SKees Cookconfig CC_STACKPROTECTOR 4518779657dSKees Cook def_bool n 45219952a92SKees Cook help 4538779657dSKees Cook Set when a stack-protector mode is enabled, so that the build 4548779657dSKees Cook can enable kernel-side support for the GCC feature. 4558779657dSKees Cook 4568779657dSKees Cookchoice 4578779657dSKees Cook prompt "Stack Protector buffer overflow detection" 4588779657dSKees Cook depends on HAVE_CC_STACKPROTECTOR 4598779657dSKees Cook default CC_STACKPROTECTOR_NONE 4608779657dSKees Cook help 4618779657dSKees Cook This option turns on the "stack-protector" GCC feature. This 46219952a92SKees Cook feature puts, at the beginning of functions, a canary value on 46319952a92SKees Cook the stack just before the return address, and validates 46419952a92SKees Cook the value just before actually returning. Stack based buffer 46519952a92SKees Cook overflows (that need to overwrite this return address) now also 46619952a92SKees Cook overwrite the canary, which gets detected and the attack is then 46719952a92SKees Cook neutralized via a kernel panic. 46819952a92SKees Cook 4698779657dSKees Cookconfig CC_STACKPROTECTOR_NONE 4708779657dSKees Cook bool "None" 4718779657dSKees Cook help 4728779657dSKees Cook Disable "stack-protector" GCC feature. 4738779657dSKees Cook 4748779657dSKees Cookconfig CC_STACKPROTECTOR_REGULAR 4758779657dSKees Cook bool "Regular" 4768779657dSKees Cook select CC_STACKPROTECTOR 4778779657dSKees Cook help 4788779657dSKees Cook Functions will have the stack-protector canary logic added if they 4798779657dSKees Cook have an 8-byte or larger character array on the stack. 4808779657dSKees Cook 48119952a92SKees Cook This feature requires gcc version 4.2 or above, or a distribution 4828779657dSKees Cook gcc with the feature backported ("-fstack-protector"). 4838779657dSKees Cook 4848779657dSKees Cook On an x86 "defconfig" build, this feature adds canary checks to 4858779657dSKees Cook about 3% of all kernel functions, which increases kernel code size 4868779657dSKees Cook by about 0.3%. 4878779657dSKees Cook 4888779657dSKees Cookconfig CC_STACKPROTECTOR_STRONG 4898779657dSKees Cook bool "Strong" 4908779657dSKees Cook select CC_STACKPROTECTOR 4918779657dSKees Cook help 4928779657dSKees Cook Functions will have the stack-protector canary logic added in any 4938779657dSKees Cook of the following conditions: 4948779657dSKees Cook 4958779657dSKees Cook - local variable's address used as part of the right hand side of an 4968779657dSKees Cook assignment or function argument 4978779657dSKees Cook - local variable is an array (or union containing an array), 4988779657dSKees Cook regardless of array type or length 4998779657dSKees Cook - uses register local variables 5008779657dSKees Cook 5018779657dSKees Cook This feature requires gcc version 4.9 or above, or a distribution 5028779657dSKees Cook gcc with the feature backported ("-fstack-protector-strong"). 5038779657dSKees Cook 5048779657dSKees Cook On an x86 "defconfig" build, this feature adds canary checks to 5058779657dSKees Cook about 20% of all kernel functions, which increases the kernel code 5068779657dSKees Cook size by about 2%. 5078779657dSKees Cook 5088779657dSKees Cookendchoice 50919952a92SKees Cook 510a5967db9SStephen Rothwellconfig THIN_ARCHIVES 511a5967db9SStephen Rothwell bool 512a5967db9SStephen Rothwell help 513a5967db9SStephen Rothwell Select this if the architecture wants to use thin archives 514a5967db9SStephen Rothwell instead of ld -r to create the built-in.o files. 515a5967db9SStephen Rothwell 516b67067f1SNicholas Pigginconfig LD_DEAD_CODE_DATA_ELIMINATION 517b67067f1SNicholas Piggin bool 518b67067f1SNicholas Piggin help 519b67067f1SNicholas Piggin Select this if the architecture wants to do dead code and 520b67067f1SNicholas Piggin data elimination with the linker by compiling with 521b67067f1SNicholas Piggin -ffunction-sections -fdata-sections and linking with 522b67067f1SNicholas Piggin --gc-sections. 523b67067f1SNicholas Piggin 524b67067f1SNicholas Piggin This requires that the arch annotates or otherwise protects 525b67067f1SNicholas Piggin its external entry points from being discarded. Linker scripts 526b67067f1SNicholas Piggin must also merge .text.*, .data.*, and .bss.* correctly into 5270f4c4af0SNicholas Piggin output sections. Care must be taken not to pull in unrelated 5280f4c4af0SNicholas Piggin sections (e.g., '.text.init'). Typically '.' in section names 5290f4c4af0SNicholas Piggin is used to distinguish them from label names / C identifiers. 530b67067f1SNicholas Piggin 5310f60a8efSKees Cookconfig HAVE_ARCH_WITHIN_STACK_FRAMES 5320f60a8efSKees Cook bool 5330f60a8efSKees Cook help 5340f60a8efSKees Cook An architecture should select this if it can walk the kernel stack 5350f60a8efSKees Cook frames to determine if an object is part of either the arguments 5360f60a8efSKees Cook or local variables (i.e. that it excludes saved return addresses, 5370f60a8efSKees Cook and similar) by implementing an inline arch_within_stack_frames(), 5380f60a8efSKees Cook which is used by CONFIG_HARDENED_USERCOPY. 5390f60a8efSKees Cook 54091d1aa43SFrederic Weisbeckerconfig HAVE_CONTEXT_TRACKING 5412b1d5024SFrederic Weisbecker bool 5422b1d5024SFrederic Weisbecker help 54391d1aa43SFrederic Weisbecker Provide kernel/user boundaries probes necessary for subsystems 54491d1aa43SFrederic Weisbecker that need it, such as userspace RCU extended quiescent state. 54591d1aa43SFrederic Weisbecker Syscalls need to be wrapped inside user_exit()-user_enter() through 54691d1aa43SFrederic Weisbecker the slow path using TIF_NOHZ flag. Exceptions handlers must be 54791d1aa43SFrederic Weisbecker wrapped as well. Irqs are already protected inside 54891d1aa43SFrederic Weisbecker rcu_irq_enter/rcu_irq_exit() but preemption or signal handling on 54991d1aa43SFrederic Weisbecker irq exit still need to be protected. 5502b1d5024SFrederic Weisbecker 551b952741cSFrederic Weisbeckerconfig HAVE_VIRT_CPU_ACCOUNTING 552b952741cSFrederic Weisbecker bool 553b952741cSFrederic Weisbecker 55440565b5aSStanislaw Gruszkaconfig ARCH_HAS_SCALED_CPUTIME 55540565b5aSStanislaw Gruszka bool 55640565b5aSStanislaw Gruszka 557554b0004SKevin Hilmanconfig HAVE_VIRT_CPU_ACCOUNTING_GEN 558554b0004SKevin Hilman bool 559554b0004SKevin Hilman default y if 64BIT 560554b0004SKevin Hilman help 561554b0004SKevin Hilman With VIRT_CPU_ACCOUNTING_GEN, cputime_t becomes 64-bit. 562554b0004SKevin Hilman Before enabling this option, arch code must be audited 563554b0004SKevin Hilman to ensure there are no races in concurrent read/write of 564554b0004SKevin Hilman cputime_t. For example, reading/writing 64-bit cputime_t on 565554b0004SKevin Hilman some 32-bit arches may require multiple accesses, so proper 566554b0004SKevin Hilman locking is needed to protect against concurrent accesses. 567554b0004SKevin Hilman 568554b0004SKevin Hilman 569fdf9c356SFrederic Weisbeckerconfig HAVE_IRQ_TIME_ACCOUNTING 570fdf9c356SFrederic Weisbecker bool 571fdf9c356SFrederic Weisbecker help 572fdf9c356SFrederic Weisbecker Archs need to ensure they use a high enough resolution clock to 573fdf9c356SFrederic Weisbecker support irq time accounting and then call enable_sched_clock_irqtime(). 574fdf9c356SFrederic Weisbecker 57515626062SGerald Schaeferconfig HAVE_ARCH_TRANSPARENT_HUGEPAGE 57615626062SGerald Schaefer bool 57715626062SGerald Schaefer 578a00cc7d9SMatthew Wilcoxconfig HAVE_ARCH_TRANSPARENT_HUGEPAGE_PUD 579a00cc7d9SMatthew Wilcox bool 580a00cc7d9SMatthew Wilcox 5810ddab1d2SToshi Kaniconfig HAVE_ARCH_HUGE_VMAP 5820ddab1d2SToshi Kani bool 5830ddab1d2SToshi Kani 5840f8975ecSPavel Emelyanovconfig HAVE_ARCH_SOFT_DIRTY 5850f8975ecSPavel Emelyanov bool 5860f8975ecSPavel Emelyanov 587786d35d4SDavid Howellsconfig HAVE_MOD_ARCH_SPECIFIC 588786d35d4SDavid Howells bool 589786d35d4SDavid Howells help 590786d35d4SDavid Howells The arch uses struct mod_arch_specific to store data. Many arches 591786d35d4SDavid Howells just need a simple module loader without arch specific data - those 592786d35d4SDavid Howells should not enable this. 593786d35d4SDavid Howells 594786d35d4SDavid Howellsconfig MODULES_USE_ELF_RELA 595786d35d4SDavid Howells bool 596786d35d4SDavid Howells help 597786d35d4SDavid Howells Modules only use ELF RELA relocations. Modules with ELF REL 598786d35d4SDavid Howells relocations will give an error. 599786d35d4SDavid Howells 600786d35d4SDavid Howellsconfig MODULES_USE_ELF_REL 601786d35d4SDavid Howells bool 602786d35d4SDavid Howells help 603786d35d4SDavid Howells Modules only use ELF REL relocations. Modules with ELF RELA 604786d35d4SDavid Howells relocations will give an error. 605786d35d4SDavid Howells 606b92021b0SRusty Russellconfig HAVE_UNDERSCORE_SYMBOL_PREFIX 607b92021b0SRusty Russell bool 608b92021b0SRusty Russell help 609b92021b0SRusty Russell Some architectures generate an _ in front of C symbols; things like 610b92021b0SRusty Russell module loading and assembly files need to know about this. 611b92021b0SRusty Russell 612cc1f0274SFrederic Weisbeckerconfig HAVE_IRQ_EXIT_ON_IRQ_STACK 613cc1f0274SFrederic Weisbecker bool 614cc1f0274SFrederic Weisbecker help 615cc1f0274SFrederic Weisbecker Architecture doesn't only execute the irq handler on the irq stack 616cc1f0274SFrederic Weisbecker but also irq_exit(). This way we can process softirqs on this irq 617cc1f0274SFrederic Weisbecker stack instead of switching to a new one when we call __do_softirq() 618cc1f0274SFrederic Weisbecker in the end of an hardirq. 619cc1f0274SFrederic Weisbecker This spares a stack switch and improves cache usage on softirq 620cc1f0274SFrederic Weisbecker processing. 621cc1f0274SFrederic Weisbecker 622235a8f02SKirill A. Shutemovconfig PGTABLE_LEVELS 623235a8f02SKirill A. Shutemov int 624235a8f02SKirill A. Shutemov default 2 625235a8f02SKirill A. Shutemov 6262b68f6caSKees Cookconfig ARCH_HAS_ELF_RANDOMIZE 6272b68f6caSKees Cook bool 6282b68f6caSKees Cook help 6292b68f6caSKees Cook An architecture supports choosing randomized locations for 6302b68f6caSKees Cook stack, mmap, brk, and ET_DYN. Defined functions: 6312b68f6caSKees Cook - arch_mmap_rnd() 632204db6edSKees Cook - arch_randomize_brk() 6332b68f6caSKees Cook 634d07e2259SDaniel Cashmanconfig HAVE_ARCH_MMAP_RND_BITS 635d07e2259SDaniel Cashman bool 636d07e2259SDaniel Cashman help 637d07e2259SDaniel Cashman An arch should select this symbol if it supports setting a variable 638d07e2259SDaniel Cashman number of bits for use in establishing the base address for mmap 639d07e2259SDaniel Cashman allocations, has MMU enabled and provides values for both: 640d07e2259SDaniel Cashman - ARCH_MMAP_RND_BITS_MIN 641d07e2259SDaniel Cashman - ARCH_MMAP_RND_BITS_MAX 642d07e2259SDaniel Cashman 6435f56a5dfSJiri Slabyconfig HAVE_EXIT_THREAD 6445f56a5dfSJiri Slaby bool 6455f56a5dfSJiri Slaby help 6465f56a5dfSJiri Slaby An architecture implements exit_thread. 6475f56a5dfSJiri Slaby 648d07e2259SDaniel Cashmanconfig ARCH_MMAP_RND_BITS_MIN 649d07e2259SDaniel Cashman int 650d07e2259SDaniel Cashman 651d07e2259SDaniel Cashmanconfig ARCH_MMAP_RND_BITS_MAX 652d07e2259SDaniel Cashman int 653d07e2259SDaniel Cashman 654d07e2259SDaniel Cashmanconfig ARCH_MMAP_RND_BITS_DEFAULT 655d07e2259SDaniel Cashman int 656d07e2259SDaniel Cashman 657d07e2259SDaniel Cashmanconfig ARCH_MMAP_RND_BITS 658d07e2259SDaniel Cashman int "Number of bits to use for ASLR of mmap base address" if EXPERT 659d07e2259SDaniel Cashman range ARCH_MMAP_RND_BITS_MIN ARCH_MMAP_RND_BITS_MAX 660d07e2259SDaniel Cashman default ARCH_MMAP_RND_BITS_DEFAULT if ARCH_MMAP_RND_BITS_DEFAULT 661d07e2259SDaniel Cashman default ARCH_MMAP_RND_BITS_MIN 662d07e2259SDaniel Cashman depends on HAVE_ARCH_MMAP_RND_BITS 663d07e2259SDaniel Cashman help 664d07e2259SDaniel Cashman This value can be used to select the number of bits to use to 665d07e2259SDaniel Cashman determine the random offset to the base address of vma regions 666d07e2259SDaniel Cashman resulting from mmap allocations. This value will be bounded 667d07e2259SDaniel Cashman by the architecture's minimum and maximum supported values. 668d07e2259SDaniel Cashman 669d07e2259SDaniel Cashman This value can be changed after boot using the 670d07e2259SDaniel Cashman /proc/sys/vm/mmap_rnd_bits tunable 671d07e2259SDaniel Cashman 672d07e2259SDaniel Cashmanconfig HAVE_ARCH_MMAP_RND_COMPAT_BITS 673d07e2259SDaniel Cashman bool 674d07e2259SDaniel Cashman help 675d07e2259SDaniel Cashman An arch should select this symbol if it supports running applications 676d07e2259SDaniel Cashman in compatibility mode, supports setting a variable number of bits for 677d07e2259SDaniel Cashman use in establishing the base address for mmap allocations, has MMU 678d07e2259SDaniel Cashman enabled and provides values for both: 679d07e2259SDaniel Cashman - ARCH_MMAP_RND_COMPAT_BITS_MIN 680d07e2259SDaniel Cashman - ARCH_MMAP_RND_COMPAT_BITS_MAX 681d07e2259SDaniel Cashman 682d07e2259SDaniel Cashmanconfig ARCH_MMAP_RND_COMPAT_BITS_MIN 683d07e2259SDaniel Cashman int 684d07e2259SDaniel Cashman 685d07e2259SDaniel Cashmanconfig ARCH_MMAP_RND_COMPAT_BITS_MAX 686d07e2259SDaniel Cashman int 687d07e2259SDaniel Cashman 688d07e2259SDaniel Cashmanconfig ARCH_MMAP_RND_COMPAT_BITS_DEFAULT 689d07e2259SDaniel Cashman int 690d07e2259SDaniel Cashman 691d07e2259SDaniel Cashmanconfig ARCH_MMAP_RND_COMPAT_BITS 692d07e2259SDaniel Cashman int "Number of bits to use for ASLR of mmap base address for compatible applications" if EXPERT 693d07e2259SDaniel Cashman range ARCH_MMAP_RND_COMPAT_BITS_MIN ARCH_MMAP_RND_COMPAT_BITS_MAX 694d07e2259SDaniel Cashman default ARCH_MMAP_RND_COMPAT_BITS_DEFAULT if ARCH_MMAP_RND_COMPAT_BITS_DEFAULT 695d07e2259SDaniel Cashman default ARCH_MMAP_RND_COMPAT_BITS_MIN 696d07e2259SDaniel Cashman depends on HAVE_ARCH_MMAP_RND_COMPAT_BITS 697d07e2259SDaniel Cashman help 698d07e2259SDaniel Cashman This value can be used to select the number of bits to use to 699d07e2259SDaniel Cashman determine the random offset to the base address of vma regions 700d07e2259SDaniel Cashman resulting from mmap allocations for compatible applications This 701d07e2259SDaniel Cashman value will be bounded by the architecture's minimum and maximum 702d07e2259SDaniel Cashman supported values. 703d07e2259SDaniel Cashman 704d07e2259SDaniel Cashman This value can be changed after boot using the 705d07e2259SDaniel Cashman /proc/sys/vm/mmap_rnd_compat_bits tunable 706d07e2259SDaniel Cashman 7071b028f78SDmitry Safonovconfig HAVE_ARCH_COMPAT_MMAP_BASES 7081b028f78SDmitry Safonov bool 7091b028f78SDmitry Safonov help 7101b028f78SDmitry Safonov This allows 64bit applications to invoke 32-bit mmap() syscall 7111b028f78SDmitry Safonov and vice-versa 32-bit applications to call 64-bit mmap(). 7121b028f78SDmitry Safonov Required for applications doing different bitness syscalls. 7131b028f78SDmitry Safonov 7143033f14aSJosh Triplettconfig HAVE_COPY_THREAD_TLS 7153033f14aSJosh Triplett bool 7163033f14aSJosh Triplett help 7173033f14aSJosh Triplett Architecture provides copy_thread_tls to accept tls argument via 7183033f14aSJosh Triplett normal C parameter passing, rather than extracting the syscall 7193033f14aSJosh Triplett argument from pt_regs. 7203033f14aSJosh Triplett 721b9ab5ebbSJosh Poimboeufconfig HAVE_STACK_VALIDATION 722b9ab5ebbSJosh Poimboeuf bool 723b9ab5ebbSJosh Poimboeuf help 724b9ab5ebbSJosh Poimboeuf Architecture supports the 'objtool check' host tool command, which 725b9ab5ebbSJosh Poimboeuf performs compile-time stack metadata validation. 726b9ab5ebbSJosh Poimboeuf 727af085d90SJosh Poimboeufconfig HAVE_RELIABLE_STACKTRACE 728af085d90SJosh Poimboeuf bool 729af085d90SJosh Poimboeuf help 730af085d90SJosh Poimboeuf Architecture has a save_stack_trace_tsk_reliable() function which 731af085d90SJosh Poimboeuf only returns a stack trace if it can guarantee the trace is reliable. 732af085d90SJosh Poimboeuf 733468a9428SGeorge Spelvinconfig HAVE_ARCH_HASH 734468a9428SGeorge Spelvin bool 735468a9428SGeorge Spelvin default n 736468a9428SGeorge Spelvin help 737468a9428SGeorge Spelvin If this is set, the architecture provides an <asm/hash.h> 738468a9428SGeorge Spelvin file which provides platform-specific implementations of some 739468a9428SGeorge Spelvin functions in <linux/hash.h> or fs/namei.c. 740468a9428SGeorge Spelvin 7413a495511SWilliam Breathitt Grayconfig ISA_BUS_API 7423a495511SWilliam Breathitt Gray def_bool ISA 7433a495511SWilliam Breathitt Gray 744d2125043SAl Viro# 745d2125043SAl Viro# ABI hall of shame 746d2125043SAl Viro# 747d2125043SAl Viroconfig CLONE_BACKWARDS 748d2125043SAl Viro bool 749d2125043SAl Viro help 750d2125043SAl Viro Architecture has tls passed as the 4th argument of clone(2), 751d2125043SAl Viro not the 5th one. 752d2125043SAl Viro 753d2125043SAl Viroconfig CLONE_BACKWARDS2 754d2125043SAl Viro bool 755d2125043SAl Viro help 756d2125043SAl Viro Architecture has the first two arguments of clone(2) swapped. 757d2125043SAl Viro 758dfa9771aSMichal Simekconfig CLONE_BACKWARDS3 759dfa9771aSMichal Simek bool 760dfa9771aSMichal Simek help 761dfa9771aSMichal Simek Architecture has tls passed as the 3rd argument of clone(2), 762dfa9771aSMichal Simek not the 5th one. 763dfa9771aSMichal Simek 764eaca6eaeSAl Viroconfig ODD_RT_SIGACTION 765eaca6eaeSAl Viro bool 766eaca6eaeSAl Viro help 767eaca6eaeSAl Viro Architecture has unusual rt_sigaction(2) arguments 768eaca6eaeSAl Viro 7690a0e8cdfSAl Viroconfig OLD_SIGSUSPEND 7700a0e8cdfSAl Viro bool 7710a0e8cdfSAl Viro help 7720a0e8cdfSAl Viro Architecture has old sigsuspend(2) syscall, of one-argument variety 7730a0e8cdfSAl Viro 7740a0e8cdfSAl Viroconfig OLD_SIGSUSPEND3 7750a0e8cdfSAl Viro bool 7760a0e8cdfSAl Viro help 7770a0e8cdfSAl Viro Even weirder antique ABI - three-argument sigsuspend(2) 7780a0e8cdfSAl Viro 779495dfbf7SAl Viroconfig OLD_SIGACTION 780495dfbf7SAl Viro bool 781495dfbf7SAl Viro help 782495dfbf7SAl Viro Architecture has old sigaction(2) syscall. Nope, not the same 783495dfbf7SAl Viro as OLD_SIGSUSPEND | OLD_SIGSUSPEND3 - alpha has sigsuspend(2), 784495dfbf7SAl Viro but fairly different variant of sigaction(2), thanks to OSF/1 785495dfbf7SAl Viro compatibility... 786495dfbf7SAl Viro 787495dfbf7SAl Viroconfig COMPAT_OLD_SIGACTION 788495dfbf7SAl Viro bool 789495dfbf7SAl Viro 7900d4a619bSChristoph Hellwigconfig ARCH_NO_COHERENT_DMA_MMAP 7910d4a619bSChristoph Hellwig bool 7920d4a619bSChristoph Hellwig 793fff7fb0bSZhaoxiu Zengconfig CPU_NO_EFFICIENT_FFS 794fff7fb0bSZhaoxiu Zeng def_bool n 795fff7fb0bSZhaoxiu Zeng 796ba14a194SAndy Lutomirskiconfig HAVE_ARCH_VMAP_STACK 797ba14a194SAndy Lutomirski def_bool n 798ba14a194SAndy Lutomirski help 799ba14a194SAndy Lutomirski An arch should select this symbol if it can support kernel stacks 800ba14a194SAndy Lutomirski in vmalloc space. This means: 801ba14a194SAndy Lutomirski 802ba14a194SAndy Lutomirski - vmalloc space must be large enough to hold many kernel stacks. 803ba14a194SAndy Lutomirski This may rule out many 32-bit architectures. 804ba14a194SAndy Lutomirski 805ba14a194SAndy Lutomirski - Stacks in vmalloc space need to work reliably. For example, if 806ba14a194SAndy Lutomirski vmap page tables are created on demand, either this mechanism 807ba14a194SAndy Lutomirski needs to work while the stack points to a virtual address with 808ba14a194SAndy Lutomirski unpopulated page tables or arch code (switch_to() and switch_mm(), 809ba14a194SAndy Lutomirski most likely) needs to ensure that the stack's page table entries 810ba14a194SAndy Lutomirski are populated before running on a possibly unpopulated stack. 811ba14a194SAndy Lutomirski 812ba14a194SAndy Lutomirski - If the stack overflows into a guard page, something reasonable 813ba14a194SAndy Lutomirski should happen. The definition of "reasonable" is flexible, but 814ba14a194SAndy Lutomirski instantly rebooting without logging anything would be unfriendly. 815ba14a194SAndy Lutomirski 816ba14a194SAndy Lutomirskiconfig VMAP_STACK 817ba14a194SAndy Lutomirski default y 818ba14a194SAndy Lutomirski bool "Use a virtually-mapped stack" 819ba14a194SAndy Lutomirski depends on HAVE_ARCH_VMAP_STACK && !KASAN 820ba14a194SAndy Lutomirski ---help--- 821ba14a194SAndy Lutomirski Enable this if you want the use virtually-mapped kernel stacks 822ba14a194SAndy Lutomirski with guard pages. This causes kernel stack overflows to be 823ba14a194SAndy Lutomirski caught immediately rather than causing difficult-to-diagnose 824ba14a194SAndy Lutomirski corruption. 825ba14a194SAndy Lutomirski 826ba14a194SAndy Lutomirski This is presently incompatible with KASAN because KASAN expects 827ba14a194SAndy Lutomirski the stack to map directly to the KASAN shadow map using a formula 828ba14a194SAndy Lutomirski that is incorrect if the stack is in vmalloc space. 829ba14a194SAndy Lutomirski 830ad21fc4fSLaura Abbottconfig ARCH_OPTIONAL_KERNEL_RWX 831ad21fc4fSLaura Abbott def_bool n 832ad21fc4fSLaura Abbott 833ad21fc4fSLaura Abbottconfig ARCH_OPTIONAL_KERNEL_RWX_DEFAULT 834ad21fc4fSLaura Abbott def_bool n 835ad21fc4fSLaura Abbott 836ad21fc4fSLaura Abbottconfig ARCH_HAS_STRICT_KERNEL_RWX 837ad21fc4fSLaura Abbott def_bool n 838ad21fc4fSLaura Abbott 8390f5bf6d0SLaura Abbottconfig STRICT_KERNEL_RWX 840ad21fc4fSLaura Abbott bool "Make kernel text and rodata read-only" if ARCH_OPTIONAL_KERNEL_RWX 841ad21fc4fSLaura Abbott depends on ARCH_HAS_STRICT_KERNEL_RWX 842ad21fc4fSLaura Abbott default !ARCH_OPTIONAL_KERNEL_RWX || ARCH_OPTIONAL_KERNEL_RWX_DEFAULT 843ad21fc4fSLaura Abbott help 844ad21fc4fSLaura Abbott If this is set, kernel text and rodata memory will be made read-only, 845ad21fc4fSLaura Abbott and non-text memory will be made non-executable. This provides 846ad21fc4fSLaura Abbott protection against certain security exploits (e.g. executing the heap 847ad21fc4fSLaura Abbott or modifying text) 848ad21fc4fSLaura Abbott 849ad21fc4fSLaura Abbott These features are considered standard security practice these days. 850ad21fc4fSLaura Abbott You should say Y here in almost all cases. 851ad21fc4fSLaura Abbott 852ad21fc4fSLaura Abbottconfig ARCH_HAS_STRICT_MODULE_RWX 853ad21fc4fSLaura Abbott def_bool n 854ad21fc4fSLaura Abbott 8550f5bf6d0SLaura Abbottconfig STRICT_MODULE_RWX 856ad21fc4fSLaura Abbott bool "Set loadable kernel module data as NX and text as RO" if ARCH_OPTIONAL_KERNEL_RWX 857ad21fc4fSLaura Abbott depends on ARCH_HAS_STRICT_MODULE_RWX && MODULES 858ad21fc4fSLaura Abbott default !ARCH_OPTIONAL_KERNEL_RWX || ARCH_OPTIONAL_KERNEL_RWX_DEFAULT 859ad21fc4fSLaura Abbott help 860ad21fc4fSLaura Abbott If this is set, module text and rodata memory will be made read-only, 861ad21fc4fSLaura Abbott and non-text memory will be made non-executable. This provides 862ad21fc4fSLaura Abbott protection against certain security exploits (e.g. writing to text) 863ad21fc4fSLaura Abbott 8641a8b6d76SMao Wenanconfig ARCH_WANT_RELAX_ORDER 8651a8b6d76SMao Wenan bool 8661a8b6d76SMao Wenan 8672521f2c2SPeter Oberparleitersource "kernel/gcov/Kconfig" 868