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Greg Kroah-Hartmanb2441312017-11-01 15:07:57 +01001# SPDX-License-Identifier: GPL-2.0
Mathieu Desnoyersfb32e032008-02-02 15:10:33 -05002#
3# General architecture dependent options
4#
Mathieu Desnoyers125e5642008-02-02 15:10:36 -05005
Hari Bathini692f66f2017-05-08 15:56:18 -07006config CRASH_CORE
7 bool
8
Dave Young2965faa2015-09-09 15:38:55 -07009config KEXEC_CORE
Hari Bathini692f66f2017-05-08 15:56:18 -070010 select CRASH_CORE
Dave Young2965faa2015-09-09 15:38:55 -070011 bool
12
Thiago Jung Bauermann467d2782016-12-19 16:22:32 -080013config HAVE_IMA_KEXEC
14 bool
15
Mathieu Desnoyers125e5642008-02-02 15:10:36 -050016config OPROFILE
Robert Richterb309a292010-02-26 15:01:23 +010017 tristate "OProfile system profiling"
Mathieu Desnoyers125e5642008-02-02 15:10:36 -050018 depends on PROFILING
19 depends on HAVE_OPROFILE
Ingo Molnard69d59f2008-12-12 09:38:57 +010020 select RING_BUFFER
Christian Borntraeger9a5963eb2009-09-16 21:56:49 +020021 select RING_BUFFER_ALLOW_SWAP
Mathieu Desnoyers125e5642008-02-02 15:10:36 -050022 help
23 OProfile is a profiling system capable of profiling the
24 whole system, include the kernel, kernel modules, libraries,
25 and applications.
26
27 If unsure, say N.
28
Jason Yeh4d4036e2009-07-08 13:49:38 +020029config OPROFILE_EVENT_MULTIPLEX
30 bool "OProfile multiplexing support (EXPERIMENTAL)"
31 default n
32 depends on OPROFILE && X86
33 help
34 The number of hardware counters is limited. The multiplexing
35 feature enables OProfile to gather more events than counters
36 are provided by the hardware. This is realized by switching
Masahiro Yamada9332ef92017-02-27 14:28:47 -080037 between events at a user specified time interval.
Jason Yeh4d4036e2009-07-08 13:49:38 +020038
39 If unsure, say N.
40
Mathieu Desnoyers125e5642008-02-02 15:10:36 -050041config HAVE_OPROFILE
Jan Beulich9ba16082008-10-15 22:01:38 -070042 bool
Mathieu Desnoyers125e5642008-02-02 15:10:36 -050043
Robert Richterdcfce4a2011-10-11 17:11:08 +020044config OPROFILE_NMI_TIMER
45 def_bool y
Anton Blanchardaf9feeb2015-04-09 12:52:55 +100046 depends on PERF_EVENTS && HAVE_PERF_EVENTS_NMI && !PPC64
Robert Richterdcfce4a2011-10-11 17:11:08 +020047
Mathieu Desnoyers125e5642008-02-02 15:10:36 -050048config KPROBES
49 bool "Kprobes"
Masami Hiramatsu05ed1602010-09-13 19:25:41 +090050 depends on MODULES
Mathieu Desnoyers125e5642008-02-02 15:10:36 -050051 depends on HAVE_KPROBES
Masami Hiramatsu05ed1602010-09-13 19:25:41 +090052 select KALLSYMS
Mathieu Desnoyers125e5642008-02-02 15:10:36 -050053 help
54 Kprobes allows you to trap at almost any kernel address and
55 execute a callback function. register_kprobe() establishes
56 a probepoint and specifies the callback. Kprobes is useful
57 for kernel debugging, non-intrusive instrumentation and testing.
58 If in doubt, say "N".
59
Steven Rostedt45f81b12010-10-29 12:33:43 -040060config JUMP_LABEL
Ingo Molnarc5905af2012-02-24 08:31:31 +010061 bool "Optimize very unlikely/likely branches"
Steven Rostedt45f81b12010-10-29 12:33:43 -040062 depends on HAVE_ARCH_JUMP_LABEL
63 help
Ingo Molnarc5905af2012-02-24 08:31:31 +010064 This option enables a transparent branch optimization that
65 makes certain almost-always-true or almost-always-false branch
66 conditions even cheaper to execute within the kernel.
Steven Rostedt45f81b12010-10-29 12:33:43 -040067
Ingo Molnarc5905af2012-02-24 08:31:31 +010068 Certain performance-sensitive kernel code, such as trace points,
69 scheduler functionality, networking code and KVM have such
70 branches and include support for this optimization technique.
71
72 If it is detected that the compiler has support for "asm goto",
73 the kernel will compile such branches with just a nop
74 instruction. When the condition flag is toggled to true, the
75 nop will be converted to a jump instruction to execute the
76 conditional block of instructions.
77
78 This technique lowers overhead and stress on the branch prediction
79 of the processor and generally makes the kernel faster. The update
80 of the condition is slower, but those are always very rare.
81
82 ( On 32-bit x86, the necessary options added to the compiler
83 flags may increase the size of the kernel slightly. )
Steven Rostedt45f81b12010-10-29 12:33:43 -040084
Peter Zijlstra1987c942015-07-27 18:32:09 +020085config STATIC_KEYS_SELFTEST
86 bool "Static key selftest"
87 depends on JUMP_LABEL
88 help
89 Boot time self-test of the branch patching code.
90
Masami Hiramatsuafd66252010-02-25 08:34:07 -050091config OPTPROBES
Masami Hiramatsu5cc718b2010-03-15 13:00:54 -040092 def_bool y
93 depends on KPROBES && HAVE_OPTPROBES
Masami Hiramatsua30b85d2017-10-20 08:43:39 +090094 select TASKS_RCU if PREEMPT
Masami Hiramatsuafd66252010-02-25 08:34:07 -050095
Masami Hiramatsue7dbfe32012-09-28 17:15:20 +090096config KPROBES_ON_FTRACE
97 def_bool y
98 depends on KPROBES && HAVE_KPROBES_ON_FTRACE
99 depends on DYNAMIC_FTRACE_WITH_REGS
100 help
101 If function tracer is enabled and the arch supports full
102 passing of pt_regs to function tracing, then kprobes can
103 optimize on top of function tracing.
104
Srikar Dronamraju2b144492012-02-09 14:56:42 +0530105config UPROBES
David A. Long09294e32014-03-07 10:32:22 -0500106 def_bool n
Allen Paise8f4aa62016-10-13 10:06:13 +0530107 depends on ARCH_SUPPORTS_UPROBES
Srikar Dronamraju2b144492012-02-09 14:56:42 +0530108 help
Ingo Molnar7b2d81d2012-02-17 09:27:41 +0100109 Uprobes is the user-space counterpart to kprobes: they
110 enable instrumentation applications (such as 'perf probe')
111 to establish unintrusive probes in user-space binaries and
112 libraries, by executing handler functions when the probes
113 are hit by user-space applications.
114
115 ( These probes come in the form of single-byte breakpoints,
116 managed by the kernel and kept transparent to the probed
117 application. )
Srikar Dronamraju2b144492012-02-09 14:56:42 +0530118
James Hoganc19fa942012-05-30 11:23:23 +0100119config HAVE_64BIT_ALIGNED_ACCESS
120 def_bool 64BIT && !HAVE_EFFICIENT_UNALIGNED_ACCESS
121 help
122 Some architectures require 64 bit accesses to be 64 bit
123 aligned, which also requires structs containing 64 bit values
124 to be 64 bit aligned too. This includes some 32 bit
125 architectures which can do 64 bit accesses, as well as 64 bit
126 architectures without unaligned access.
127
128 This symbol should be selected by an architecture if 64 bit
129 accesses are required to be 64 bit aligned in this way even
130 though it is not a 64 bit architecture.
131
132 See Documentation/unaligned-memory-access.txt for more
133 information on the topic of unaligned memory accesses.
134
Johannes Berg58340a02008-07-25 01:45:33 -0700135config HAVE_EFFICIENT_UNALIGNED_ACCESS
Jan Beulich9ba16082008-10-15 22:01:38 -0700136 bool
Johannes Berg58340a02008-07-25 01:45:33 -0700137 help
138 Some architectures are unable to perform unaligned accesses
139 without the use of get_unaligned/put_unaligned. Others are
140 unable to perform such accesses efficiently (e.g. trap on
141 unaligned access and require fixing it up in the exception
142 handler.)
143
144 This symbol should be selected by an architecture if it can
145 perform unaligned accesses efficiently to allow different
146 code paths to be selected for these cases. Some network
147 drivers, for example, could opt to not fix up alignment
148 problems with received packets if doing so would not help
149 much.
150
151 See Documentation/unaligned-memory-access.txt for more
152 information on the topic of unaligned memory accesses.
153
David Woodhousecf66bb92012-12-03 16:25:40 +0000154config ARCH_USE_BUILTIN_BSWAP
155 bool
156 help
157 Modern versions of GCC (since 4.4) have builtin functions
158 for handling byte-swapping. Using these, instead of the old
159 inline assembler that the architecture code provides in the
160 __arch_bswapXX() macros, allows the compiler to see what's
161 happening and offers more opportunity for optimisation. In
162 particular, the compiler will be able to combine the byteswap
163 with a nearby load or store and use load-and-swap or
164 store-and-swap instructions if the architecture has them. It
165 should almost *never* result in code which is worse than the
166 hand-coded assembler in <asm/swab.h>. But just in case it
167 does, the use of the builtins is optional.
168
169 Any architecture with load-and-swap or store-and-swap
170 instructions should set this. And it shouldn't hurt to set it
171 on architectures that don't have such instructions.
172
Ananth N Mavinakayanahalli9edddaa2008-03-04 14:28:37 -0800173config KRETPROBES
174 def_bool y
175 depends on KPROBES && HAVE_KRETPROBES
176
Avi Kivity7c68af62009-09-19 09:40:22 +0300177config USER_RETURN_NOTIFIER
178 bool
179 depends on HAVE_USER_RETURN_NOTIFIER
180 help
181 Provide a kernel-internal notification when a cpu is about to
182 switch to user mode.
183
Rik van Riel28b2ee22008-07-23 21:27:05 -0700184config HAVE_IOREMAP_PROT
Jan Beulich9ba16082008-10-15 22:01:38 -0700185 bool
Rik van Riel28b2ee22008-07-23 21:27:05 -0700186
Mathieu Desnoyers125e5642008-02-02 15:10:36 -0500187config HAVE_KPROBES
Jan Beulich9ba16082008-10-15 22:01:38 -0700188 bool
Ananth N Mavinakayanahalli9edddaa2008-03-04 14:28:37 -0800189
190config HAVE_KRETPROBES
Jan Beulich9ba16082008-10-15 22:01:38 -0700191 bool
Arthur Kepner74bc7ce2008-04-29 01:00:30 -0700192
Masami Hiramatsuafd66252010-02-25 08:34:07 -0500193config HAVE_OPTPROBES
194 bool
Cong Wangd314d742012-03-23 15:01:51 -0700195
Masami Hiramatsue7dbfe32012-09-28 17:15:20 +0900196config HAVE_KPROBES_ON_FTRACE
197 bool
198
Masami Hiramatsu540adea2018-01-13 02:55:03 +0900199config HAVE_FUNCTION_ERROR_INJECTION
Josef Bacik9802d862017-12-11 11:36:48 -0500200 bool
201
Petr Mladek42a0bb32016-05-20 17:00:33 -0700202config HAVE_NMI
203 bool
204
Roland McGrath1f5a4ad2008-07-25 19:45:57 -0700205#
206# An arch should select this if it provides all these things:
207#
208# task_pt_regs() in asm/processor.h or asm/ptrace.h
209# arch_has_single_step() if there is hardware single-step support
210# arch_has_block_step() if there is hardware block-step support
Roland McGrath1f5a4ad2008-07-25 19:45:57 -0700211# asm/syscall.h supplying asm-generic/syscall.h interface
212# linux/regset.h user_regset interfaces
213# CORE_DUMP_USE_REGSET #define'd in linux/elf.h
214# TIF_SYSCALL_TRACE calls tracehook_report_syscall_{entry,exit}
215# TIF_NOTIFY_RESUME calls tracehook_notify_resume()
216# signal delivery calls tracehook_signal_handler()
217#
218config HAVE_ARCH_TRACEHOOK
Jan Beulich9ba16082008-10-15 22:01:38 -0700219 bool
Roland McGrath1f5a4ad2008-07-25 19:45:57 -0700220
Marek Szyprowskic64be2b2011-12-29 13:09:51 +0100221config HAVE_DMA_CONTIGUOUS
222 bool
223
Thomas Gleixner29d5e042012-04-20 13:05:45 +0000224config GENERIC_SMP_IDLE_THREAD
225 bool
226
Kevin Hilman485cf5d2013-04-24 17:19:13 -0700227config GENERIC_IDLE_POLL_SETUP
228 bool
229
Daniel Micay6974f0c2017-07-12 14:36:10 -0700230config ARCH_HAS_FORTIFY_SOURCE
231 bool
232 help
233 An architecture should select this when it can successfully
234 build and run with CONFIG_FORTIFY_SOURCE.
235
Daniel Borkmannd2852a22017-02-21 16:09:33 +0100236# Select if arch has all set_memory_ro/rw/x/nx() functions in asm/cacheflush.h
237config ARCH_HAS_SET_MEMORY
238 bool
239
David Howells05008712018-01-02 15:12:01 +0000240# Select if arch init_task must go in the __init_task_data section
241config ARCH_TASK_STRUCT_ON_STACK
Thomas Gleixnera4a2eb42012-05-03 09:02:48 +0000242 bool
243
Thomas Gleixnerf5e10282012-05-05 15:05:48 +0000244# Select if arch has its private alloc_task_struct() function
245config ARCH_TASK_STRUCT_ALLOCATOR
246 bool
247
Kees Cook59054292017-08-16 13:00:58 -0700248config HAVE_ARCH_THREAD_STRUCT_WHITELIST
249 bool
250 depends on !ARCH_TASK_STRUCT_ALLOCATOR
251 help
252 An architecture should select this to provide hardened usercopy
253 knowledge about what region of the thread_struct should be
254 whitelisted for copying to userspace. Normally this is only the
255 FPU registers. Specifically, arch_thread_struct_whitelist()
256 should be implemented. Without this, the entire thread_struct
257 field in task_struct will be left whitelisted.
258
Linus Torvaldsb235bee2016-06-24 15:09:37 -0700259# Select if arch has its private alloc_thread_stack() function
260config ARCH_THREAD_STACK_ALLOCATOR
Thomas Gleixnerf5e10282012-05-05 15:05:48 +0000261 bool
262
Ingo Molnar5aaeb5c2015-07-17 12:28:12 +0200263# Select if arch wants to size task_struct dynamically via arch_task_struct_size:
264config ARCH_WANTS_DYNAMIC_TASK_STRUCT
265 bool
266
Heiko Carstensf850c30c2010-02-10 17:25:17 +0100267config HAVE_REGS_AND_STACK_ACCESS_API
268 bool
Heiko Carstense01292b2010-02-18 14:25:21 +0100269 help
270 This symbol should be selected by an architecure if it supports
271 the API needed to access registers and stack entries from pt_regs,
272 declared in asm/ptrace.h
273 For example the kprobes-based event tracer needs this API.
Heiko Carstensf850c30c2010-02-10 17:25:17 +0100274
Mathieu Desnoyersd7822b12018-06-02 08:43:54 -0400275config HAVE_RSEQ
276 bool
277 depends on HAVE_REGS_AND_STACK_ACCESS_API
278 help
279 This symbol should be selected by an architecture if it
280 supports an implementation of restartable sequences.
281
David Brownell9483a572008-07-23 21:26:48 -0700282config HAVE_CLK
Jan Beulich9ba16082008-10-15 22:01:38 -0700283 bool
David Brownell9483a572008-07-23 21:26:48 -0700284 help
285 The <linux/clk.h> calls support software clock gating and
286 thus are a key power management tool on many systems.
287
K.Prasad62a038d2009-06-01 23:43:33 +0530288config HAVE_HW_BREAKPOINT
289 bool
Frederic Weisbecker99e8c5a2009-12-17 01:33:54 +0100290 depends on PERF_EVENTS
K.Prasad62a038d2009-06-01 23:43:33 +0530291
Frederic Weisbecker01027522010-04-11 18:55:56 +0200292config HAVE_MIXED_BREAKPOINTS_REGS
293 bool
294 depends on HAVE_HW_BREAKPOINT
295 help
296 Depending on the arch implementation of hardware breakpoints,
297 some of them have separate registers for data and instruction
298 breakpoints addresses, others have mixed registers to store
299 them but define the access type in a control register.
300 Select this option if your arch implements breakpoints under the
301 latter fashion.
302
Avi Kivity7c68af62009-09-19 09:40:22 +0300303config HAVE_USER_RETURN_NOTIFIER
304 bool
Ingo Molnara1922ed2009-09-07 08:19:51 +0200305
Frederic Weisbeckerc01d4322010-05-15 22:57:48 +0200306config HAVE_PERF_EVENTS_NMI
307 bool
Frederic Weisbecker23637d42010-05-15 23:15:20 +0200308 help
309 System hardware can generate an NMI using the perf event
310 subsystem. Also has support for calculating CPU cycle events
311 to determine how many clock cycles in a given period.
Frederic Weisbeckerc01d4322010-05-15 22:57:48 +0200312
Nicholas Piggin05a4a952017-07-12 14:35:46 -0700313config HAVE_HARDLOCKUP_DETECTOR_PERF
314 bool
315 depends on HAVE_PERF_EVENTS_NMI
316 help
317 The arch chooses to use the generic perf-NMI-based hardlockup
318 detector. Must define HAVE_PERF_EVENTS_NMI.
319
320config HAVE_NMI_WATCHDOG
321 depends on HAVE_NMI
322 bool
323 help
324 The arch provides a low level NMI watchdog. It provides
325 asm/nmi.h, and defines its own arch_touch_nmi_watchdog().
326
327config HAVE_HARDLOCKUP_DETECTOR_ARCH
328 bool
329 select HAVE_NMI_WATCHDOG
330 help
331 The arch chooses to provide its own hardlockup detector, which is
332 a superset of the HAVE_NMI_WATCHDOG. It also conforms to config
333 interfaces and parameters provided by hardlockup detector subsystem.
334
Jiri Olsac5e63192012-08-07 15:20:36 +0200335config HAVE_PERF_REGS
336 bool
337 help
338 Support selective register dumps for perf events. This includes
339 bit-mapping of each registers and a unique architecture id.
340
Jiri Olsac5ebced2012-08-07 15:20:40 +0200341config HAVE_PERF_USER_STACK_DUMP
342 bool
343 help
344 Support user stack dumps for perf event samples. This needs
345 access to the user stack pointer which is not unified across
346 architectures.
347
Jason Baronbf5438fc2010-09-17 11:09:00 -0400348config HAVE_ARCH_JUMP_LABEL
349 bool
350
Peter Zijlstra26723912011-05-24 17:12:00 -0700351config HAVE_RCU_TABLE_FREE
352 bool
353
Huang Yingdf013ff2011-07-13 13:14:22 +0800354config ARCH_HAVE_NMI_SAFE_CMPXCHG
355 bool
356
Heiko Carstens43570fd2012-01-12 17:17:27 -0800357config HAVE_ALIGNED_STRUCT_PAGE
358 bool
359 help
360 This makes sure that struct pages are double word aligned and that
361 e.g. the SLUB allocator can perform double word atomic operations
362 on a struct page for better performance. However selecting this
363 might increase the size of a struct page by a word.
364
Heiko Carstens41561532012-01-12 17:17:30 -0800365config HAVE_CMPXCHG_LOCAL
366 bool
367
Heiko Carstens25654092012-01-12 17:17:33 -0800368config HAVE_CMPXCHG_DOUBLE
369 bool
370
Paul E. McKenney77e58492017-01-14 13:32:50 -0800371config ARCH_WEAK_RELEASE_ACQUIRE
372 bool
373
Will Deaconc1d7e012012-07-30 14:42:46 -0700374config ARCH_WANT_IPC_PARSE_VERSION
375 bool
376
377config ARCH_WANT_COMPAT_IPC_PARSE_VERSION
378 bool
379
Chris Metcalf48b25c42012-03-15 13:13:38 -0400380config ARCH_WANT_OLD_COMPAT_IPC
Will Deaconc1d7e012012-07-30 14:42:46 -0700381 select ARCH_WANT_COMPAT_IPC_PARSE_VERSION
Chris Metcalf48b25c42012-03-15 13:13:38 -0400382 bool
383
Will Drewrye2cfabdf2012-04-12 16:47:57 -0500384config HAVE_ARCH_SECCOMP_FILTER
385 bool
386 help
Will Drewryfb0fadf2012-04-12 16:48:02 -0500387 An arch should select this symbol if it provides all of these things:
Will Drewrybb6ea432012-04-12 16:48:01 -0500388 - syscall_get_arch()
389 - syscall_get_arguments()
390 - syscall_rollback()
391 - syscall_set_return_value()
Will Drewryfb0fadf2012-04-12 16:48:02 -0500392 - SIGSYS siginfo_t support
393 - secure_computing is called from a ptrace_event()-safe context
394 - secure_computing return value is checked and a return value of -1
395 results in the system call being skipped immediately.
Kees Cook48dc92b2014-06-25 16:08:24 -0700396 - seccomp syscall wired up
Will Drewrye2cfabdf2012-04-12 16:47:57 -0500397
398config SECCOMP_FILTER
399 def_bool y
400 depends on HAVE_ARCH_SECCOMP_FILTER && SECCOMP && NET
401 help
402 Enable tasks to build secure computing environments defined
403 in terms of Berkeley Packet Filter programs which implement
404 task-defined system call filtering polices.
405
Mauro Carvalho Chehab5fb94e92018-05-08 15:14:57 -0300406 See Documentation/userspace-api/seccomp_filter.rst for details.
Will Drewrye2cfabdf2012-04-12 16:47:57 -0500407
Masahiro Yamadad148eac2018-06-14 19:36:45 +0900408config HAVE_STACKPROTECTOR
Kees Cook19952a92013-12-19 11:35:58 -0800409 bool
410 help
411 An arch should select this symbol if:
Kees Cook19952a92013-12-19 11:35:58 -0800412 - it has implemented a stack canary (e.g. __stack_chk_guard)
413
Masahiro Yamada2a61f472018-05-28 18:22:00 +0900414config CC_HAS_STACKPROTECTOR_NONE
415 def_bool $(cc-option,-fno-stack-protector)
416
Linus Torvalds050e9ba2018-06-14 12:21:18 +0900417config STACKPROTECTOR
Masahiro Yamada2a61f472018-05-28 18:22:00 +0900418 bool "Stack Protector buffer overflow detection"
Masahiro Yamadad148eac2018-06-14 19:36:45 +0900419 depends on HAVE_STACKPROTECTOR
Masahiro Yamada2a61f472018-05-28 18:22:00 +0900420 depends on $(cc-option,-fstack-protector)
421 default y
Kees Cook87796572013-12-19 11:35:59 -0800422 help
423 This option turns on the "stack-protector" GCC feature. This
Kees Cook19952a92013-12-19 11:35:58 -0800424 feature puts, at the beginning of functions, a canary value on
425 the stack just before the return address, and validates
426 the value just before actually returning. Stack based buffer
427 overflows (that need to overwrite this return address) now also
428 overwrite the canary, which gets detected and the attack is then
429 neutralized via a kernel panic.
430
Kees Cook87796572013-12-19 11:35:59 -0800431 Functions will have the stack-protector canary logic added if they
432 have an 8-byte or larger character array on the stack.
433
Kees Cook19952a92013-12-19 11:35:58 -0800434 This feature requires gcc version 4.2 or above, or a distribution
Kees Cook87796572013-12-19 11:35:59 -0800435 gcc with the feature backported ("-fstack-protector").
436
437 On an x86 "defconfig" build, this feature adds canary checks to
438 about 3% of all kernel functions, which increases kernel code size
439 by about 0.3%.
440
Linus Torvalds050e9ba2018-06-14 12:21:18 +0900441config STACKPROTECTOR_STRONG
Masahiro Yamada2a61f472018-05-28 18:22:00 +0900442 bool "Strong Stack Protector"
Linus Torvalds050e9ba2018-06-14 12:21:18 +0900443 depends on STACKPROTECTOR
Masahiro Yamada2a61f472018-05-28 18:22:00 +0900444 depends on $(cc-option,-fstack-protector-strong)
445 default y
Kees Cook87796572013-12-19 11:35:59 -0800446 help
447 Functions will have the stack-protector canary logic added in any
448 of the following conditions:
449
450 - local variable's address used as part of the right hand side of an
451 assignment or function argument
452 - local variable is an array (or union containing an array),
453 regardless of array type or length
454 - uses register local variables
455
456 This feature requires gcc version 4.9 or above, or a distribution
457 gcc with the feature backported ("-fstack-protector-strong").
458
459 On an x86 "defconfig" build, this feature adds canary checks to
460 about 20% of all kernel functions, which increases the kernel code
461 size by about 2%.
462
Kees Cook0f60a8e2016-07-12 16:19:48 -0700463config HAVE_ARCH_WITHIN_STACK_FRAMES
464 bool
465 help
466 An architecture should select this if it can walk the kernel stack
467 frames to determine if an object is part of either the arguments
468 or local variables (i.e. that it excludes saved return addresses,
469 and similar) by implementing an inline arch_within_stack_frames(),
470 which is used by CONFIG_HARDENED_USERCOPY.
471
Frederic Weisbecker91d1aa432012-11-27 19:33:25 +0100472config HAVE_CONTEXT_TRACKING
Frederic Weisbecker2b1d5022012-07-11 20:26:30 +0200473 bool
474 help
Frederic Weisbecker91d1aa432012-11-27 19:33:25 +0100475 Provide kernel/user boundaries probes necessary for subsystems
476 that need it, such as userspace RCU extended quiescent state.
477 Syscalls need to be wrapped inside user_exit()-user_enter() through
478 the slow path using TIF_NOHZ flag. Exceptions handlers must be
479 wrapped as well. Irqs are already protected inside
480 rcu_irq_enter/rcu_irq_exit() but preemption or signal handling on
481 irq exit still need to be protected.
Frederic Weisbecker2b1d5022012-07-11 20:26:30 +0200482
Frederic Weisbeckerb9527412012-06-16 15:39:34 +0200483config HAVE_VIRT_CPU_ACCOUNTING
484 bool
485
Stanislaw Gruszka40565b52016-11-15 03:06:51 +0100486config ARCH_HAS_SCALED_CPUTIME
487 bool
488
Kevin Hilman554b0002013-09-16 15:28:21 -0700489config HAVE_VIRT_CPU_ACCOUNTING_GEN
490 bool
491 default y if 64BIT
492 help
493 With VIRT_CPU_ACCOUNTING_GEN, cputime_t becomes 64-bit.
494 Before enabling this option, arch code must be audited
495 to ensure there are no races in concurrent read/write of
496 cputime_t. For example, reading/writing 64-bit cputime_t on
497 some 32-bit arches may require multiple accesses, so proper
498 locking is needed to protect against concurrent accesses.
499
500
Frederic Weisbeckerfdf9c352012-09-09 14:56:31 +0200501config HAVE_IRQ_TIME_ACCOUNTING
502 bool
503 help
504 Archs need to ensure they use a high enough resolution clock to
505 support irq time accounting and then call enable_sched_clock_irqtime().
506
Gerald Schaefer15626062012-10-08 16:30:04 -0700507config HAVE_ARCH_TRANSPARENT_HUGEPAGE
508 bool
509
Matthew Wilcoxa00cc7d2017-02-24 14:57:02 -0800510config HAVE_ARCH_TRANSPARENT_HUGEPAGE_PUD
511 bool
512
Toshi Kani0ddab1d2015-04-14 15:47:20 -0700513config HAVE_ARCH_HUGE_VMAP
514 bool
515
Pavel Emelyanov0f8975e2013-07-03 15:01:20 -0700516config HAVE_ARCH_SOFT_DIRTY
517 bool
518
David Howells786d35d2012-09-28 14:31:03 +0930519config HAVE_MOD_ARCH_SPECIFIC
520 bool
521 help
522 The arch uses struct mod_arch_specific to store data. Many arches
523 just need a simple module loader without arch specific data - those
524 should not enable this.
525
526config MODULES_USE_ELF_RELA
527 bool
528 help
529 Modules only use ELF RELA relocations. Modules with ELF REL
530 relocations will give an error.
531
532config MODULES_USE_ELF_REL
533 bool
534 help
535 Modules only use ELF REL relocations. Modules with ELF RELA
536 relocations will give an error.
537
Frederic Weisbeckercc1f0272013-09-24 17:17:47 +0200538config HAVE_IRQ_EXIT_ON_IRQ_STACK
539 bool
540 help
541 Architecture doesn't only execute the irq handler on the irq stack
542 but also irq_exit(). This way we can process softirqs on this irq
543 stack instead of switching to a new one when we call __do_softirq()
544 in the end of an hardirq.
545 This spares a stack switch and improves cache usage on softirq
546 processing.
547
Kirill A. Shutemov235a8f02015-04-14 15:46:17 -0700548config PGTABLE_LEVELS
549 int
550 default 2
551
Kees Cook2b68f6c2015-04-14 15:48:00 -0700552config ARCH_HAS_ELF_RANDOMIZE
553 bool
554 help
555 An architecture supports choosing randomized locations for
556 stack, mmap, brk, and ET_DYN. Defined functions:
557 - arch_mmap_rnd()
Kees Cook204db6e2015-04-14 15:48:12 -0700558 - arch_randomize_brk()
Kees Cook2b68f6c2015-04-14 15:48:00 -0700559
Daniel Cashmand07e2252016-01-14 15:19:53 -0800560config HAVE_ARCH_MMAP_RND_BITS
561 bool
562 help
563 An arch should select this symbol if it supports setting a variable
564 number of bits for use in establishing the base address for mmap
565 allocations, has MMU enabled and provides values for both:
566 - ARCH_MMAP_RND_BITS_MIN
567 - ARCH_MMAP_RND_BITS_MAX
568
Jiri Slaby5f56a5d2016-05-20 17:00:16 -0700569config HAVE_EXIT_THREAD
570 bool
571 help
572 An architecture implements exit_thread.
573
Daniel Cashmand07e2252016-01-14 15:19:53 -0800574config ARCH_MMAP_RND_BITS_MIN
575 int
576
577config ARCH_MMAP_RND_BITS_MAX
578 int
579
580config ARCH_MMAP_RND_BITS_DEFAULT
581 int
582
583config ARCH_MMAP_RND_BITS
584 int "Number of bits to use for ASLR of mmap base address" if EXPERT
585 range ARCH_MMAP_RND_BITS_MIN ARCH_MMAP_RND_BITS_MAX
586 default ARCH_MMAP_RND_BITS_DEFAULT if ARCH_MMAP_RND_BITS_DEFAULT
587 default ARCH_MMAP_RND_BITS_MIN
588 depends on HAVE_ARCH_MMAP_RND_BITS
589 help
590 This value can be used to select the number of bits to use to
591 determine the random offset to the base address of vma regions
592 resulting from mmap allocations. This value will be bounded
593 by the architecture's minimum and maximum supported values.
594
595 This value can be changed after boot using the
596 /proc/sys/vm/mmap_rnd_bits tunable
597
598config HAVE_ARCH_MMAP_RND_COMPAT_BITS
599 bool
600 help
601 An arch should select this symbol if it supports running applications
602 in compatibility mode, supports setting a variable number of bits for
603 use in establishing the base address for mmap allocations, has MMU
604 enabled and provides values for both:
605 - ARCH_MMAP_RND_COMPAT_BITS_MIN
606 - ARCH_MMAP_RND_COMPAT_BITS_MAX
607
608config ARCH_MMAP_RND_COMPAT_BITS_MIN
609 int
610
611config ARCH_MMAP_RND_COMPAT_BITS_MAX
612 int
613
614config ARCH_MMAP_RND_COMPAT_BITS_DEFAULT
615 int
616
617config ARCH_MMAP_RND_COMPAT_BITS
618 int "Number of bits to use for ASLR of mmap base address for compatible applications" if EXPERT
619 range ARCH_MMAP_RND_COMPAT_BITS_MIN ARCH_MMAP_RND_COMPAT_BITS_MAX
620 default ARCH_MMAP_RND_COMPAT_BITS_DEFAULT if ARCH_MMAP_RND_COMPAT_BITS_DEFAULT
621 default ARCH_MMAP_RND_COMPAT_BITS_MIN
622 depends on HAVE_ARCH_MMAP_RND_COMPAT_BITS
623 help
624 This value can be used to select the number of bits to use to
625 determine the random offset to the base address of vma regions
626 resulting from mmap allocations for compatible applications This
627 value will be bounded by the architecture's minimum and maximum
628 supported values.
629
630 This value can be changed after boot using the
631 /proc/sys/vm/mmap_rnd_compat_bits tunable
632
Dmitry Safonov1b028f72017-03-06 17:17:19 +0300633config HAVE_ARCH_COMPAT_MMAP_BASES
634 bool
635 help
636 This allows 64bit applications to invoke 32-bit mmap() syscall
637 and vice-versa 32-bit applications to call 64-bit mmap().
638 Required for applications doing different bitness syscalls.
639
Josh Triplett3033f14a2015-06-25 15:01:19 -0700640config HAVE_COPY_THREAD_TLS
641 bool
642 help
643 Architecture provides copy_thread_tls to accept tls argument via
644 normal C parameter passing, rather than extracting the syscall
645 argument from pt_regs.
646
Josh Poimboeufb9ab5eb2016-02-28 22:22:42 -0600647config HAVE_STACK_VALIDATION
648 bool
649 help
650 Architecture supports the 'objtool check' host tool command, which
651 performs compile-time stack metadata validation.
652
Josh Poimboeufaf085d92017-02-13 19:42:28 -0600653config HAVE_RELIABLE_STACKTRACE
654 bool
655 help
656 Architecture has a save_stack_trace_tsk_reliable() function which
657 only returns a stack trace if it can guarantee the trace is reliable.
658
George Spelvin468a9422016-05-26 22:11:51 -0400659config HAVE_ARCH_HASH
660 bool
661 default n
662 help
663 If this is set, the architecture provides an <asm/hash.h>
664 file which provides platform-specific implementations of some
665 functions in <linux/hash.h> or fs/namei.c.
666
William Breathitt Gray3a495512016-05-27 18:08:27 -0400667config ISA_BUS_API
668 def_bool ISA
669
Al Virod2125042012-10-23 13:17:59 -0400670#
671# ABI hall of shame
672#
673config CLONE_BACKWARDS
674 bool
675 help
676 Architecture has tls passed as the 4th argument of clone(2),
677 not the 5th one.
678
679config CLONE_BACKWARDS2
680 bool
681 help
682 Architecture has the first two arguments of clone(2) swapped.
683
Michal Simekdfa97712013-08-13 16:00:53 -0700684config CLONE_BACKWARDS3
685 bool
686 help
687 Architecture has tls passed as the 3rd argument of clone(2),
688 not the 5th one.
689
Al Viroeaca6ea2012-11-25 23:12:10 -0500690config ODD_RT_SIGACTION
691 bool
692 help
693 Architecture has unusual rt_sigaction(2) arguments
694
Al Viro0a0e8cd2012-12-25 16:04:12 -0500695config OLD_SIGSUSPEND
696 bool
697 help
698 Architecture has old sigsuspend(2) syscall, of one-argument variety
699
700config OLD_SIGSUSPEND3
701 bool
702 help
703 Even weirder antique ABI - three-argument sigsuspend(2)
704
Al Viro495dfbf2012-12-25 19:09:45 -0500705config OLD_SIGACTION
706 bool
707 help
708 Architecture has old sigaction(2) syscall. Nope, not the same
709 as OLD_SIGSUSPEND | OLD_SIGSUSPEND3 - alpha has sigsuspend(2),
710 but fairly different variant of sigaction(2), thanks to OSF/1
711 compatibility...
712
713config COMPAT_OLD_SIGACTION
714 bool
715
Deepa Dinamanid4703dd2018-03-13 21:03:27 -0700716config 64BIT_TIME
717 def_bool ARCH_HAS_64BIT_TIME
718 help
719 This should be selected by all architectures that need to support
720 new system calls with a 64-bit time_t. This is relevant on all 32-bit
721 architectures, and 64-bit architectures as part of compat syscall
722 handling.
723
Deepa Dinamani17435e52018-03-13 21:03:28 -0700724config COMPAT_32BIT_TIME
725 def_bool (!64BIT && 64BIT_TIME) || COMPAT
726 help
727 This enables 32 bit time_t support in addition to 64 bit time_t support.
728 This is relevant on all 32-bit architectures, and 64-bit architectures
729 as part of compat syscall handling.
730
Christoph Hellwig0d4a6192016-01-20 15:01:22 -0800731config ARCH_NO_COHERENT_DMA_MMAP
732 bool
733
Zhaoxiu Zengfff7fb02016-05-20 17:03:57 -0700734config CPU_NO_EFFICIENT_FFS
735 def_bool n
736
Andy Lutomirskiba14a192016-08-11 02:35:21 -0700737config HAVE_ARCH_VMAP_STACK
738 def_bool n
739 help
740 An arch should select this symbol if it can support kernel stacks
741 in vmalloc space. This means:
742
743 - vmalloc space must be large enough to hold many kernel stacks.
744 This may rule out many 32-bit architectures.
745
746 - Stacks in vmalloc space need to work reliably. For example, if
747 vmap page tables are created on demand, either this mechanism
748 needs to work while the stack points to a virtual address with
749 unpopulated page tables or arch code (switch_to() and switch_mm(),
750 most likely) needs to ensure that the stack's page table entries
751 are populated before running on a possibly unpopulated stack.
752
753 - If the stack overflows into a guard page, something reasonable
754 should happen. The definition of "reasonable" is flexible, but
755 instantly rebooting without logging anything would be unfriendly.
756
757config VMAP_STACK
758 default y
759 bool "Use a virtually-mapped stack"
760 depends on HAVE_ARCH_VMAP_STACK && !KASAN
761 ---help---
762 Enable this if you want the use virtually-mapped kernel stacks
763 with guard pages. This causes kernel stack overflows to be
764 caught immediately rather than causing difficult-to-diagnose
765 corruption.
766
767 This is presently incompatible with KASAN because KASAN expects
768 the stack to map directly to the KASAN shadow map using a formula
769 that is incorrect if the stack is in vmalloc space.
770
Laura Abbottad21fc42017-02-06 16:31:57 -0800771config ARCH_OPTIONAL_KERNEL_RWX
772 def_bool n
773
774config ARCH_OPTIONAL_KERNEL_RWX_DEFAULT
775 def_bool n
776
777config ARCH_HAS_STRICT_KERNEL_RWX
778 def_bool n
779
Laura Abbott0f5bf6d2017-02-06 16:31:58 -0800780config STRICT_KERNEL_RWX
Laura Abbottad21fc42017-02-06 16:31:57 -0800781 bool "Make kernel text and rodata read-only" if ARCH_OPTIONAL_KERNEL_RWX
782 depends on ARCH_HAS_STRICT_KERNEL_RWX
783 default !ARCH_OPTIONAL_KERNEL_RWX || ARCH_OPTIONAL_KERNEL_RWX_DEFAULT
784 help
785 If this is set, kernel text and rodata memory will be made read-only,
786 and non-text memory will be made non-executable. This provides
787 protection against certain security exploits (e.g. executing the heap
788 or modifying text)
789
790 These features are considered standard security practice these days.
791 You should say Y here in almost all cases.
792
793config ARCH_HAS_STRICT_MODULE_RWX
794 def_bool n
795
Laura Abbott0f5bf6d2017-02-06 16:31:58 -0800796config STRICT_MODULE_RWX
Laura Abbottad21fc42017-02-06 16:31:57 -0800797 bool "Set loadable kernel module data as NX and text as RO" if ARCH_OPTIONAL_KERNEL_RWX
798 depends on ARCH_HAS_STRICT_MODULE_RWX && MODULES
799 default !ARCH_OPTIONAL_KERNEL_RWX || ARCH_OPTIONAL_KERNEL_RWX_DEFAULT
800 help
801 If this is set, module text and rodata memory will be made read-only,
802 and non-text memory will be made non-executable. This provides
803 protection against certain security exploits (e.g. writing to text)
804
Christoph Hellwigea8c64a2018-01-10 16:21:13 +0100805# select if the architecture provides an asm/dma-direct.h header
806config ARCH_HAS_PHYS_TO_DMA
807 bool
808
Kees Cook7a46ec02017-08-15 09:19:24 -0700809config ARCH_HAS_REFCOUNT
810 bool
811 help
812 An architecture selects this when it has implemented refcount_t
813 using open coded assembly primitives that provide an optimized
814 refcount_t implementation, possibly at the expense of some full
815 refcount state checks of CONFIG_REFCOUNT_FULL=y.
816
817 The refcount overflow check behavior, however, must be retained.
818 Catching overflows is the primary security concern for protecting
819 against bugs in reference counts.
820
Kees Cookfd25d19f2017-06-21 13:00:26 -0700821config REFCOUNT_FULL
822 bool "Perform full reference count validation at the expense of speed"
823 help
824 Enabling this switches the refcounting infrastructure from a fast
825 unchecked atomic_t implementation to a fully state checked
826 implementation, which can be (slightly) slower but provides protections
827 against various use-after-free conditions that can be used in
828 security flaw exploits.
829
Peter Oberparleiter2521f2c2009-06-17 16:28:08 -0700830source "kernel/gcov/Kconfig"
Masahiro Yamada45332b12018-07-05 15:24:12 +0900831
832source "scripts/gcc-plugins/Kconfig"