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Mathieu Desnoyersfb32e032008-02-02 15:10:33 -05001#
2# General architecture dependent options
3#
Mathieu Desnoyers125e5642008-02-02 15:10:36 -05004
Dave Young2965faa2015-09-09 15:38:55 -07005config KEXEC_CORE
6 bool
7
Thiago Jung Bauermann467d2782016-12-19 16:22:32 -08008config HAVE_IMA_KEXEC
9 bool
10
Mathieu Desnoyers125e5642008-02-02 15:10:36 -050011config OPROFILE
Robert Richterb309a292010-02-26 15:01:23 +010012 tristate "OProfile system profiling"
Mathieu Desnoyers125e5642008-02-02 15:10:36 -050013 depends on PROFILING
14 depends on HAVE_OPROFILE
Ingo Molnard69d59f2008-12-12 09:38:57 +010015 select RING_BUFFER
Christian Borntraeger9a5963e2009-09-16 21:56:49 +020016 select RING_BUFFER_ALLOW_SWAP
Mathieu Desnoyers125e5642008-02-02 15:10:36 -050017 help
18 OProfile is a profiling system capable of profiling the
19 whole system, include the kernel, kernel modules, libraries,
20 and applications.
21
22 If unsure, say N.
23
Jason Yeh4d4036e2009-07-08 13:49:38 +020024config OPROFILE_EVENT_MULTIPLEX
25 bool "OProfile multiplexing support (EXPERIMENTAL)"
26 default n
27 depends on OPROFILE && X86
28 help
29 The number of hardware counters is limited. The multiplexing
30 feature enables OProfile to gather more events than counters
31 are provided by the hardware. This is realized by switching
32 between events at an user specified time interval.
33
34 If unsure, say N.
35
Mathieu Desnoyers125e5642008-02-02 15:10:36 -050036config HAVE_OPROFILE
Jan Beulich9ba16082008-10-15 22:01:38 -070037 bool
Mathieu Desnoyers125e5642008-02-02 15:10:36 -050038
Robert Richterdcfce4a2011-10-11 17:11:08 +020039config OPROFILE_NMI_TIMER
40 def_bool y
Anton Blanchardaf9feeb2015-04-09 12:52:55 +100041 depends on PERF_EVENTS && HAVE_PERF_EVENTS_NMI && !PPC64
Robert Richterdcfce4a2011-10-11 17:11:08 +020042
Mathieu Desnoyers125e5642008-02-02 15:10:36 -050043config KPROBES
44 bool "Kprobes"
Masami Hiramatsu05ed1602010-09-13 19:25:41 +090045 depends on MODULES
Mathieu Desnoyers125e5642008-02-02 15:10:36 -050046 depends on HAVE_KPROBES
Masami Hiramatsu05ed1602010-09-13 19:25:41 +090047 select KALLSYMS
Mathieu Desnoyers125e5642008-02-02 15:10:36 -050048 help
49 Kprobes allows you to trap at almost any kernel address and
50 execute a callback function. register_kprobe() establishes
51 a probepoint and specifies the callback. Kprobes is useful
52 for kernel debugging, non-intrusive instrumentation and testing.
53 If in doubt, say "N".
54
Steven Rostedt45f81b12010-10-29 12:33:43 -040055config JUMP_LABEL
Ingo Molnarc5905af2012-02-24 08:31:31 +010056 bool "Optimize very unlikely/likely branches"
Steven Rostedt45f81b12010-10-29 12:33:43 -040057 depends on HAVE_ARCH_JUMP_LABEL
58 help
Ingo Molnarc5905af2012-02-24 08:31:31 +010059 This option enables a transparent branch optimization that
60 makes certain almost-always-true or almost-always-false branch
61 conditions even cheaper to execute within the kernel.
Steven Rostedt45f81b12010-10-29 12:33:43 -040062
Ingo Molnarc5905af2012-02-24 08:31:31 +010063 Certain performance-sensitive kernel code, such as trace points,
64 scheduler functionality, networking code and KVM have such
65 branches and include support for this optimization technique.
66
67 If it is detected that the compiler has support for "asm goto",
68 the kernel will compile such branches with just a nop
69 instruction. When the condition flag is toggled to true, the
70 nop will be converted to a jump instruction to execute the
71 conditional block of instructions.
72
73 This technique lowers overhead and stress on the branch prediction
74 of the processor and generally makes the kernel faster. The update
75 of the condition is slower, but those are always very rare.
76
77 ( On 32-bit x86, the necessary options added to the compiler
78 flags may increase the size of the kernel slightly. )
Steven Rostedt45f81b12010-10-29 12:33:43 -040079
Peter Zijlstra1987c942015-07-27 18:32:09 +020080config STATIC_KEYS_SELFTEST
81 bool "Static key selftest"
82 depends on JUMP_LABEL
83 help
84 Boot time self-test of the branch patching code.
85
Masami Hiramatsuafd66252010-02-25 08:34:07 -050086config OPTPROBES
Masami Hiramatsu5cc718b2010-03-15 13:00:54 -040087 def_bool y
88 depends on KPROBES && HAVE_OPTPROBES
Masami Hiramatsuafd66252010-02-25 08:34:07 -050089 depends on !PREEMPT
Masami Hiramatsuafd66252010-02-25 08:34:07 -050090
Masami Hiramatsue7dbfe32012-09-28 17:15:20 +090091config KPROBES_ON_FTRACE
92 def_bool y
93 depends on KPROBES && HAVE_KPROBES_ON_FTRACE
94 depends on DYNAMIC_FTRACE_WITH_REGS
95 help
96 If function tracer is enabled and the arch supports full
97 passing of pt_regs to function tracing, then kprobes can
98 optimize on top of function tracing.
99
Srikar Dronamraju2b144492012-02-09 14:56:42 +0530100config UPROBES
David A. Long09294e32014-03-07 10:32:22 -0500101 def_bool n
Allen Paise8f4aa62016-10-13 10:06:13 +0530102 depends on ARCH_SUPPORTS_UPROBES
Srikar Dronamraju2b144492012-02-09 14:56:42 +0530103 help
Ingo Molnar7b2d81d2012-02-17 09:27:41 +0100104 Uprobes is the user-space counterpart to kprobes: they
105 enable instrumentation applications (such as 'perf probe')
106 to establish unintrusive probes in user-space binaries and
107 libraries, by executing handler functions when the probes
108 are hit by user-space applications.
109
110 ( These probes come in the form of single-byte breakpoints,
111 managed by the kernel and kept transparent to the probed
112 application. )
Srikar Dronamraju2b144492012-02-09 14:56:42 +0530113
James Hoganc19fa942012-05-30 11:23:23 +0100114config HAVE_64BIT_ALIGNED_ACCESS
115 def_bool 64BIT && !HAVE_EFFICIENT_UNALIGNED_ACCESS
116 help
117 Some architectures require 64 bit accesses to be 64 bit
118 aligned, which also requires structs containing 64 bit values
119 to be 64 bit aligned too. This includes some 32 bit
120 architectures which can do 64 bit accesses, as well as 64 bit
121 architectures without unaligned access.
122
123 This symbol should be selected by an architecture if 64 bit
124 accesses are required to be 64 bit aligned in this way even
125 though it is not a 64 bit architecture.
126
127 See Documentation/unaligned-memory-access.txt for more
128 information on the topic of unaligned memory accesses.
129
Johannes Berg58340a02008-07-25 01:45:33 -0700130config HAVE_EFFICIENT_UNALIGNED_ACCESS
Jan Beulich9ba16082008-10-15 22:01:38 -0700131 bool
Johannes Berg58340a02008-07-25 01:45:33 -0700132 help
133 Some architectures are unable to perform unaligned accesses
134 without the use of get_unaligned/put_unaligned. Others are
135 unable to perform such accesses efficiently (e.g. trap on
136 unaligned access and require fixing it up in the exception
137 handler.)
138
139 This symbol should be selected by an architecture if it can
140 perform unaligned accesses efficiently to allow different
141 code paths to be selected for these cases. Some network
142 drivers, for example, could opt to not fix up alignment
143 problems with received packets if doing so would not help
144 much.
145
146 See Documentation/unaligned-memory-access.txt for more
147 information on the topic of unaligned memory accesses.
148
David Woodhousecf66bb92012-12-03 16:25:40 +0000149config ARCH_USE_BUILTIN_BSWAP
150 bool
151 help
152 Modern versions of GCC (since 4.4) have builtin functions
153 for handling byte-swapping. Using these, instead of the old
154 inline assembler that the architecture code provides in the
155 __arch_bswapXX() macros, allows the compiler to see what's
156 happening and offers more opportunity for optimisation. In
157 particular, the compiler will be able to combine the byteswap
158 with a nearby load or store and use load-and-swap or
159 store-and-swap instructions if the architecture has them. It
160 should almost *never* result in code which is worse than the
161 hand-coded assembler in <asm/swab.h>. But just in case it
162 does, the use of the builtins is optional.
163
164 Any architecture with load-and-swap or store-and-swap
165 instructions should set this. And it shouldn't hurt to set it
166 on architectures that don't have such instructions.
167
Ananth N Mavinakayanahalli9edddaa2008-03-04 14:28:37 -0800168config KRETPROBES
169 def_bool y
170 depends on KPROBES && HAVE_KRETPROBES
171
Avi Kivity7c68af62009-09-19 09:40:22 +0300172config USER_RETURN_NOTIFIER
173 bool
174 depends on HAVE_USER_RETURN_NOTIFIER
175 help
176 Provide a kernel-internal notification when a cpu is about to
177 switch to user mode.
178
Rik van Riel28b2ee22008-07-23 21:27:05 -0700179config HAVE_IOREMAP_PROT
Jan Beulich9ba16082008-10-15 22:01:38 -0700180 bool
Rik van Riel28b2ee22008-07-23 21:27:05 -0700181
Mathieu Desnoyers125e5642008-02-02 15:10:36 -0500182config HAVE_KPROBES
Jan Beulich9ba16082008-10-15 22:01:38 -0700183 bool
Ananth N Mavinakayanahalli9edddaa2008-03-04 14:28:37 -0800184
185config HAVE_KRETPROBES
Jan Beulich9ba16082008-10-15 22:01:38 -0700186 bool
Arthur Kepner74bc7ce2008-04-29 01:00:30 -0700187
Masami Hiramatsuafd66252010-02-25 08:34:07 -0500188config HAVE_OPTPROBES
189 bool
Cong Wangd314d742012-03-23 15:01:51 -0700190
Masami Hiramatsue7dbfe32012-09-28 17:15:20 +0900191config HAVE_KPROBES_ON_FTRACE
192 bool
193
Petr Mladek42a0bb32016-05-20 17:00:33 -0700194config HAVE_NMI
195 bool
196
Cong Wangd314d742012-03-23 15:01:51 -0700197config HAVE_NMI_WATCHDOG
Petr Mladek42a0bb32016-05-20 17:00:33 -0700198 depends on HAVE_NMI
Cong Wangd314d742012-03-23 15:01:51 -0700199 bool
Roland McGrath1f5a4ad2008-07-25 19:45:57 -0700200#
201# An arch should select this if it provides all these things:
202#
203# task_pt_regs() in asm/processor.h or asm/ptrace.h
204# arch_has_single_step() if there is hardware single-step support
205# arch_has_block_step() if there is hardware block-step support
Roland McGrath1f5a4ad2008-07-25 19:45:57 -0700206# asm/syscall.h supplying asm-generic/syscall.h interface
207# linux/regset.h user_regset interfaces
208# CORE_DUMP_USE_REGSET #define'd in linux/elf.h
209# TIF_SYSCALL_TRACE calls tracehook_report_syscall_{entry,exit}
210# TIF_NOTIFY_RESUME calls tracehook_notify_resume()
211# signal delivery calls tracehook_signal_handler()
212#
213config HAVE_ARCH_TRACEHOOK
Jan Beulich9ba16082008-10-15 22:01:38 -0700214 bool
Roland McGrath1f5a4ad2008-07-25 19:45:57 -0700215
Marek Szyprowskic64be2b2011-12-29 13:09:51 +0100216config HAVE_DMA_CONTIGUOUS
217 bool
218
Thomas Gleixner29d5e042012-04-20 13:05:45 +0000219config GENERIC_SMP_IDLE_THREAD
220 bool
221
Kevin Hilman485cf5d2013-04-24 17:19:13 -0700222config GENERIC_IDLE_POLL_SETUP
223 bool
224
Thomas Gleixnera6359d12012-05-03 09:03:02 +0000225# Select if arch init_task initializer is different to init/init_task.c
226config ARCH_INIT_TASK
Thomas Gleixnera4a2eb42012-05-03 09:02:48 +0000227 bool
228
Thomas Gleixnerf5e10282012-05-05 15:05:48 +0000229# Select if arch has its private alloc_task_struct() function
230config ARCH_TASK_STRUCT_ALLOCATOR
231 bool
232
Linus Torvaldsb235bee2016-06-24 15:09:37 -0700233# Select if arch has its private alloc_thread_stack() function
234config ARCH_THREAD_STACK_ALLOCATOR
Thomas Gleixnerf5e10282012-05-05 15:05:48 +0000235 bool
236
Ingo Molnar5aaeb5c2015-07-17 12:28:12 +0200237# Select if arch wants to size task_struct dynamically via arch_task_struct_size:
238config ARCH_WANTS_DYNAMIC_TASK_STRUCT
239 bool
240
Heiko Carstensf850c30c2010-02-10 17:25:17 +0100241config HAVE_REGS_AND_STACK_ACCESS_API
242 bool
Heiko Carstense01292b2010-02-18 14:25:21 +0100243 help
244 This symbol should be selected by an architecure if it supports
245 the API needed to access registers and stack entries from pt_regs,
246 declared in asm/ptrace.h
247 For example the kprobes-based event tracer needs this API.
Heiko Carstensf850c30c2010-02-10 17:25:17 +0100248
David Brownell9483a572008-07-23 21:26:48 -0700249config HAVE_CLK
Jan Beulich9ba16082008-10-15 22:01:38 -0700250 bool
David Brownell9483a572008-07-23 21:26:48 -0700251 help
252 The <linux/clk.h> calls support software clock gating and
253 thus are a key power management tool on many systems.
254
Joerg Roedel5ee00bd2009-01-09 12:14:24 +0100255config HAVE_DMA_API_DEBUG
256 bool
Heiko Carstens36cd3c92009-04-09 18:48:34 +0200257
K.Prasad62a038d2009-06-01 23:43:33 +0530258config HAVE_HW_BREAKPOINT
259 bool
Frederic Weisbecker99e8c5a2009-12-17 01:33:54 +0100260 depends on PERF_EVENTS
K.Prasad62a038d2009-06-01 23:43:33 +0530261
Frederic Weisbecker01027522010-04-11 18:55:56 +0200262config HAVE_MIXED_BREAKPOINTS_REGS
263 bool
264 depends on HAVE_HW_BREAKPOINT
265 help
266 Depending on the arch implementation of hardware breakpoints,
267 some of them have separate registers for data and instruction
268 breakpoints addresses, others have mixed registers to store
269 them but define the access type in a control register.
270 Select this option if your arch implements breakpoints under the
271 latter fashion.
272
Avi Kivity7c68af62009-09-19 09:40:22 +0300273config HAVE_USER_RETURN_NOTIFIER
274 bool
Ingo Molnara1922ed2009-09-07 08:19:51 +0200275
Frederic Weisbeckerc01d4322010-05-15 22:57:48 +0200276config HAVE_PERF_EVENTS_NMI
277 bool
Frederic Weisbecker23637d42010-05-15 23:15:20 +0200278 help
279 System hardware can generate an NMI using the perf event
280 subsystem. Also has support for calculating CPU cycle events
281 to determine how many clock cycles in a given period.
Frederic Weisbeckerc01d4322010-05-15 22:57:48 +0200282
Jiri Olsac5e63192012-08-07 15:20:36 +0200283config HAVE_PERF_REGS
284 bool
285 help
286 Support selective register dumps for perf events. This includes
287 bit-mapping of each registers and a unique architecture id.
288
Jiri Olsac5ebced2012-08-07 15:20:40 +0200289config HAVE_PERF_USER_STACK_DUMP
290 bool
291 help
292 Support user stack dumps for perf event samples. This needs
293 access to the user stack pointer which is not unified across
294 architectures.
295
Jason Baronbf5438fc2010-09-17 11:09:00 -0400296config HAVE_ARCH_JUMP_LABEL
297 bool
298
Peter Zijlstra26723912011-05-24 17:12:00 -0700299config HAVE_RCU_TABLE_FREE
300 bool
301
Huang Yingdf013ff2011-07-13 13:14:22 +0800302config ARCH_HAVE_NMI_SAFE_CMPXCHG
303 bool
304
Heiko Carstens43570fd2012-01-12 17:17:27 -0800305config HAVE_ALIGNED_STRUCT_PAGE
306 bool
307 help
308 This makes sure that struct pages are double word aligned and that
309 e.g. the SLUB allocator can perform double word atomic operations
310 on a struct page for better performance. However selecting this
311 might increase the size of a struct page by a word.
312
Heiko Carstens41561532012-01-12 17:17:30 -0800313config HAVE_CMPXCHG_LOCAL
314 bool
315
Heiko Carstens25654092012-01-12 17:17:33 -0800316config HAVE_CMPXCHG_DOUBLE
317 bool
318
Will Deaconc1d7e012012-07-30 14:42:46 -0700319config ARCH_WANT_IPC_PARSE_VERSION
320 bool
321
322config ARCH_WANT_COMPAT_IPC_PARSE_VERSION
323 bool
324
Chris Metcalf48b25c42012-03-15 13:13:38 -0400325config ARCH_WANT_OLD_COMPAT_IPC
Will Deaconc1d7e012012-07-30 14:42:46 -0700326 select ARCH_WANT_COMPAT_IPC_PARSE_VERSION
Chris Metcalf48b25c42012-03-15 13:13:38 -0400327 bool
328
Will Drewrye2cfabdf2012-04-12 16:47:57 -0500329config HAVE_ARCH_SECCOMP_FILTER
330 bool
331 help
Will Drewryfb0fadf2012-04-12 16:48:02 -0500332 An arch should select this symbol if it provides all of these things:
Will Drewrybb6ea432012-04-12 16:48:01 -0500333 - syscall_get_arch()
334 - syscall_get_arguments()
335 - syscall_rollback()
336 - syscall_set_return_value()
Will Drewryfb0fadf2012-04-12 16:48:02 -0500337 - SIGSYS siginfo_t support
338 - secure_computing is called from a ptrace_event()-safe context
339 - secure_computing return value is checked and a return value of -1
340 results in the system call being skipped immediately.
Kees Cook48dc92b2014-06-25 16:08:24 -0700341 - seccomp syscall wired up
Will Drewrye2cfabdf2012-04-12 16:47:57 -0500342
343config SECCOMP_FILTER
344 def_bool y
345 depends on HAVE_ARCH_SECCOMP_FILTER && SECCOMP && NET
346 help
347 Enable tasks to build secure computing environments defined
348 in terms of Berkeley Packet Filter programs which implement
349 task-defined system call filtering polices.
350
351 See Documentation/prctl/seccomp_filter.txt for details.
352
Emese Revfy6b90bd42016-05-24 00:09:38 +0200353config HAVE_GCC_PLUGINS
354 bool
355 help
356 An arch should select this symbol if it supports building with
357 GCC plugins.
358
359menuconfig GCC_PLUGINS
360 bool "GCC plugins"
361 depends on HAVE_GCC_PLUGINS
Kees Cooka519167e2016-06-11 09:09:28 -0700362 depends on !COMPILE_TEST
Emese Revfy6b90bd42016-05-24 00:09:38 +0200363 help
364 GCC plugins are loadable modules that provide extra features to the
365 compiler. They are useful for runtime instrumentation and static analysis.
366
367 See Documentation/gcc-plugins.txt for details.
368
Emese Revfy0dae7762016-05-24 00:10:35 +0200369config GCC_PLUGIN_CYC_COMPLEXITY
Kees Cook215e2aa2016-11-08 16:27:03 -0800370 bool "Compute the cyclomatic complexity of a function" if EXPERT
Emese Revfy0dae7762016-05-24 00:10:35 +0200371 depends on GCC_PLUGINS
Kees Cook215e2aa2016-11-08 16:27:03 -0800372 depends on !COMPILE_TEST
Emese Revfy0dae7762016-05-24 00:10:35 +0200373 help
374 The complexity M of a function's control flow graph is defined as:
375 M = E - N + 2P
376 where
377
378 E = the number of edges
379 N = the number of nodes
380 P = the number of connected components (exit nodes).
381
Kees Cook215e2aa2016-11-08 16:27:03 -0800382 Enabling this plugin reports the complexity to stderr during the
383 build. It mainly serves as a simple example of how to create a
384 gcc plugin for the kernel.
385
Emese Revfy543c37c2016-05-24 00:11:37 +0200386config GCC_PLUGIN_SANCOV
387 bool
388 depends on GCC_PLUGINS
389 help
390 This plugin inserts a __sanitizer_cov_trace_pc() call at the start of
391 basic blocks. It supports all gcc versions with plugin support (from
392 gcc-4.5 on). It is based on the commit "Add fuzzing coverage support"
393 by Dmitry Vyukov <dvyukov@google.com>.
394
Emese Revfy38addce2016-06-20 20:41:19 +0200395config GCC_PLUGIN_LATENT_ENTROPY
396 bool "Generate some entropy during boot and runtime"
397 depends on GCC_PLUGINS
398 help
399 By saying Y here the kernel will instrument some kernel code to
400 extract some entropy from both original and artificially created
401 program state. This will help especially embedded systems where
402 there is little 'natural' source of entropy normally. The cost
403 is some slowdown of the boot process (about 0.5%) and fork and
404 irq processing.
405
406 Note that entropy extracted this way is not cryptographically
407 secure!
408
409 This plugin was ported from grsecurity/PaX. More information at:
410 * https://grsecurity.net/
411 * https://pax.grsecurity.net/
412
Kees Cook19952a92013-12-19 11:35:58 -0800413config HAVE_CC_STACKPROTECTOR
414 bool
415 help
416 An arch should select this symbol if:
417 - its compiler supports the -fstack-protector option
418 - it has implemented a stack canary (e.g. __stack_chk_guard)
419
420config CC_STACKPROTECTOR
Kees Cook87796572013-12-19 11:35:59 -0800421 def_bool n
Kees Cook19952a92013-12-19 11:35:58 -0800422 help
Kees Cook87796572013-12-19 11:35:59 -0800423 Set when a stack-protector mode is enabled, so that the build
424 can enable kernel-side support for the GCC feature.
425
426choice
427 prompt "Stack Protector buffer overflow detection"
428 depends on HAVE_CC_STACKPROTECTOR
429 default CC_STACKPROTECTOR_NONE
430 help
431 This option turns on the "stack-protector" GCC feature. This
Kees Cook19952a92013-12-19 11:35:58 -0800432 feature puts, at the beginning of functions, a canary value on
433 the stack just before the return address, and validates
434 the value just before actually returning. Stack based buffer
435 overflows (that need to overwrite this return address) now also
436 overwrite the canary, which gets detected and the attack is then
437 neutralized via a kernel panic.
438
Kees Cook87796572013-12-19 11:35:59 -0800439config CC_STACKPROTECTOR_NONE
440 bool "None"
441 help
442 Disable "stack-protector" GCC feature.
443
444config CC_STACKPROTECTOR_REGULAR
445 bool "Regular"
446 select CC_STACKPROTECTOR
447 help
448 Functions will have the stack-protector canary logic added if they
449 have an 8-byte or larger character array on the stack.
450
Kees Cook19952a92013-12-19 11:35:58 -0800451 This feature requires gcc version 4.2 or above, or a distribution
Kees Cook87796572013-12-19 11:35:59 -0800452 gcc with the feature backported ("-fstack-protector").
453
454 On an x86 "defconfig" build, this feature adds canary checks to
455 about 3% of all kernel functions, which increases kernel code size
456 by about 0.3%.
457
458config CC_STACKPROTECTOR_STRONG
459 bool "Strong"
460 select CC_STACKPROTECTOR
461 help
462 Functions will have the stack-protector canary logic added in any
463 of the following conditions:
464
465 - local variable's address used as part of the right hand side of an
466 assignment or function argument
467 - local variable is an array (or union containing an array),
468 regardless of array type or length
469 - uses register local variables
470
471 This feature requires gcc version 4.9 or above, or a distribution
472 gcc with the feature backported ("-fstack-protector-strong").
473
474 On an x86 "defconfig" build, this feature adds canary checks to
475 about 20% of all kernel functions, which increases the kernel code
476 size by about 2%.
477
478endchoice
Kees Cook19952a92013-12-19 11:35:58 -0800479
Stephen Rothwella5967db2016-08-24 22:29:19 +1000480config THIN_ARCHIVES
481 bool
482 help
483 Select this if the architecture wants to use thin archives
484 instead of ld -r to create the built-in.o files.
485
Nicholas Pigginb67067f2016-08-24 22:29:20 +1000486config LD_DEAD_CODE_DATA_ELIMINATION
487 bool
488 help
489 Select this if the architecture wants to do dead code and
490 data elimination with the linker by compiling with
491 -ffunction-sections -fdata-sections and linking with
492 --gc-sections.
493
494 This requires that the arch annotates or otherwise protects
495 its external entry points from being discarded. Linker scripts
496 must also merge .text.*, .data.*, and .bss.* correctly into
Nicholas Piggin0f4c4af2016-09-14 12:24:03 +1000497 output sections. Care must be taken not to pull in unrelated
498 sections (e.g., '.text.init'). Typically '.' in section names
499 is used to distinguish them from label names / C identifiers.
Nicholas Pigginb67067f2016-08-24 22:29:20 +1000500
Kees Cook0f60a8e2016-07-12 16:19:48 -0700501config HAVE_ARCH_WITHIN_STACK_FRAMES
502 bool
503 help
504 An architecture should select this if it can walk the kernel stack
505 frames to determine if an object is part of either the arguments
506 or local variables (i.e. that it excludes saved return addresses,
507 and similar) by implementing an inline arch_within_stack_frames(),
508 which is used by CONFIG_HARDENED_USERCOPY.
509
Frederic Weisbecker91d1aa432012-11-27 19:33:25 +0100510config HAVE_CONTEXT_TRACKING
Frederic Weisbecker2b1d5022012-07-11 20:26:30 +0200511 bool
512 help
Frederic Weisbecker91d1aa432012-11-27 19:33:25 +0100513 Provide kernel/user boundaries probes necessary for subsystems
514 that need it, such as userspace RCU extended quiescent state.
515 Syscalls need to be wrapped inside user_exit()-user_enter() through
516 the slow path using TIF_NOHZ flag. Exceptions handlers must be
517 wrapped as well. Irqs are already protected inside
518 rcu_irq_enter/rcu_irq_exit() but preemption or signal handling on
519 irq exit still need to be protected.
Frederic Weisbecker2b1d5022012-07-11 20:26:30 +0200520
Frederic Weisbeckerb9527412012-06-16 15:39:34 +0200521config HAVE_VIRT_CPU_ACCOUNTING
522 bool
523
Stanislaw Gruszka40565b52016-11-15 03:06:51 +0100524config ARCH_HAS_SCALED_CPUTIME
525 bool
526
Kevin Hilman554b0002013-09-16 15:28:21 -0700527config HAVE_VIRT_CPU_ACCOUNTING_GEN
528 bool
529 default y if 64BIT
530 help
531 With VIRT_CPU_ACCOUNTING_GEN, cputime_t becomes 64-bit.
532 Before enabling this option, arch code must be audited
533 to ensure there are no races in concurrent read/write of
534 cputime_t. For example, reading/writing 64-bit cputime_t on
535 some 32-bit arches may require multiple accesses, so proper
536 locking is needed to protect against concurrent accesses.
537
538
Frederic Weisbeckerfdf9c352012-09-09 14:56:31 +0200539config HAVE_IRQ_TIME_ACCOUNTING
540 bool
541 help
542 Archs need to ensure they use a high enough resolution clock to
543 support irq time accounting and then call enable_sched_clock_irqtime().
544
Gerald Schaefer15626062012-10-08 16:30:04 -0700545config HAVE_ARCH_TRANSPARENT_HUGEPAGE
546 bool
547
Toshi Kani0ddab1d2015-04-14 15:47:20 -0700548config HAVE_ARCH_HUGE_VMAP
549 bool
550
Pavel Emelyanov0f8975e2013-07-03 15:01:20 -0700551config HAVE_ARCH_SOFT_DIRTY
552 bool
553
David Howells786d35d2012-09-28 14:31:03 +0930554config HAVE_MOD_ARCH_SPECIFIC
555 bool
556 help
557 The arch uses struct mod_arch_specific to store data. Many arches
558 just need a simple module loader without arch specific data - those
559 should not enable this.
560
561config MODULES_USE_ELF_RELA
562 bool
563 help
564 Modules only use ELF RELA relocations. Modules with ELF REL
565 relocations will give an error.
566
567config MODULES_USE_ELF_REL
568 bool
569 help
570 Modules only use ELF REL relocations. Modules with ELF RELA
571 relocations will give an error.
572
Rusty Russellb92021b2013-03-15 15:04:17 +1030573config HAVE_UNDERSCORE_SYMBOL_PREFIX
574 bool
575 help
576 Some architectures generate an _ in front of C symbols; things like
577 module loading and assembly files need to know about this.
578
Frederic Weisbeckercc1f0272013-09-24 17:17:47 +0200579config HAVE_IRQ_EXIT_ON_IRQ_STACK
580 bool
581 help
582 Architecture doesn't only execute the irq handler on the irq stack
583 but also irq_exit(). This way we can process softirqs on this irq
584 stack instead of switching to a new one when we call __do_softirq()
585 in the end of an hardirq.
586 This spares a stack switch and improves cache usage on softirq
587 processing.
588
Kirill A. Shutemov235a8f02015-04-14 15:46:17 -0700589config PGTABLE_LEVELS
590 int
591 default 2
592
Kees Cook2b68f6c2015-04-14 15:48:00 -0700593config ARCH_HAS_ELF_RANDOMIZE
594 bool
595 help
596 An architecture supports choosing randomized locations for
597 stack, mmap, brk, and ET_DYN. Defined functions:
598 - arch_mmap_rnd()
Kees Cook204db6e2015-04-14 15:48:12 -0700599 - arch_randomize_brk()
Kees Cook2b68f6c2015-04-14 15:48:00 -0700600
Daniel Cashmand07e2252016-01-14 15:19:53 -0800601config HAVE_ARCH_MMAP_RND_BITS
602 bool
603 help
604 An arch should select this symbol if it supports setting a variable
605 number of bits for use in establishing the base address for mmap
606 allocations, has MMU enabled and provides values for both:
607 - ARCH_MMAP_RND_BITS_MIN
608 - ARCH_MMAP_RND_BITS_MAX
609
Jiri Slaby5f56a5d2016-05-20 17:00:16 -0700610config HAVE_EXIT_THREAD
611 bool
612 help
613 An architecture implements exit_thread.
614
Daniel Cashmand07e2252016-01-14 15:19:53 -0800615config ARCH_MMAP_RND_BITS_MIN
616 int
617
618config ARCH_MMAP_RND_BITS_MAX
619 int
620
621config ARCH_MMAP_RND_BITS_DEFAULT
622 int
623
624config ARCH_MMAP_RND_BITS
625 int "Number of bits to use for ASLR of mmap base address" if EXPERT
626 range ARCH_MMAP_RND_BITS_MIN ARCH_MMAP_RND_BITS_MAX
627 default ARCH_MMAP_RND_BITS_DEFAULT if ARCH_MMAP_RND_BITS_DEFAULT
628 default ARCH_MMAP_RND_BITS_MIN
629 depends on HAVE_ARCH_MMAP_RND_BITS
630 help
631 This value can be used to select the number of bits to use to
632 determine the random offset to the base address of vma regions
633 resulting from mmap allocations. This value will be bounded
634 by the architecture's minimum and maximum supported values.
635
636 This value can be changed after boot using the
637 /proc/sys/vm/mmap_rnd_bits tunable
638
639config HAVE_ARCH_MMAP_RND_COMPAT_BITS
640 bool
641 help
642 An arch should select this symbol if it supports running applications
643 in compatibility mode, supports setting a variable number of bits for
644 use in establishing the base address for mmap allocations, has MMU
645 enabled and provides values for both:
646 - ARCH_MMAP_RND_COMPAT_BITS_MIN
647 - ARCH_MMAP_RND_COMPAT_BITS_MAX
648
649config ARCH_MMAP_RND_COMPAT_BITS_MIN
650 int
651
652config ARCH_MMAP_RND_COMPAT_BITS_MAX
653 int
654
655config ARCH_MMAP_RND_COMPAT_BITS_DEFAULT
656 int
657
658config ARCH_MMAP_RND_COMPAT_BITS
659 int "Number of bits to use for ASLR of mmap base address for compatible applications" if EXPERT
660 range ARCH_MMAP_RND_COMPAT_BITS_MIN ARCH_MMAP_RND_COMPAT_BITS_MAX
661 default ARCH_MMAP_RND_COMPAT_BITS_DEFAULT if ARCH_MMAP_RND_COMPAT_BITS_DEFAULT
662 default ARCH_MMAP_RND_COMPAT_BITS_MIN
663 depends on HAVE_ARCH_MMAP_RND_COMPAT_BITS
664 help
665 This value can be used to select the number of bits to use to
666 determine the random offset to the base address of vma regions
667 resulting from mmap allocations for compatible applications This
668 value will be bounded by the architecture's minimum and maximum
669 supported values.
670
671 This value can be changed after boot using the
672 /proc/sys/vm/mmap_rnd_compat_bits tunable
673
Josh Triplett3033f14a2015-06-25 15:01:19 -0700674config HAVE_COPY_THREAD_TLS
675 bool
676 help
677 Architecture provides copy_thread_tls to accept tls argument via
678 normal C parameter passing, rather than extracting the syscall
679 argument from pt_regs.
680
Josh Poimboeufb9ab5eb2016-02-28 22:22:42 -0600681config HAVE_STACK_VALIDATION
682 bool
683 help
684 Architecture supports the 'objtool check' host tool command, which
685 performs compile-time stack metadata validation.
686
George Spelvin468a9422016-05-26 22:11:51 -0400687config HAVE_ARCH_HASH
688 bool
689 default n
690 help
691 If this is set, the architecture provides an <asm/hash.h>
692 file which provides platform-specific implementations of some
693 functions in <linux/hash.h> or fs/namei.c.
694
William Breathitt Gray3a495512016-05-27 18:08:27 -0400695config ISA_BUS_API
696 def_bool ISA
697
Al Virod2125042012-10-23 13:17:59 -0400698#
699# ABI hall of shame
700#
701config CLONE_BACKWARDS
702 bool
703 help
704 Architecture has tls passed as the 4th argument of clone(2),
705 not the 5th one.
706
707config CLONE_BACKWARDS2
708 bool
709 help
710 Architecture has the first two arguments of clone(2) swapped.
711
Michal Simekdfa97712013-08-13 16:00:53 -0700712config CLONE_BACKWARDS3
713 bool
714 help
715 Architecture has tls passed as the 3rd argument of clone(2),
716 not the 5th one.
717
Al Viroeaca6ea2012-11-25 23:12:10 -0500718config ODD_RT_SIGACTION
719 bool
720 help
721 Architecture has unusual rt_sigaction(2) arguments
722
Al Viro0a0e8cd2012-12-25 16:04:12 -0500723config OLD_SIGSUSPEND
724 bool
725 help
726 Architecture has old sigsuspend(2) syscall, of one-argument variety
727
728config OLD_SIGSUSPEND3
729 bool
730 help
731 Even weirder antique ABI - three-argument sigsuspend(2)
732
Al Viro495dfbf2012-12-25 19:09:45 -0500733config OLD_SIGACTION
734 bool
735 help
736 Architecture has old sigaction(2) syscall. Nope, not the same
737 as OLD_SIGSUSPEND | OLD_SIGSUSPEND3 - alpha has sigsuspend(2),
738 but fairly different variant of sigaction(2), thanks to OSF/1
739 compatibility...
740
741config COMPAT_OLD_SIGACTION
742 bool
743
Christoph Hellwig0d4a6192016-01-20 15:01:22 -0800744config ARCH_NO_COHERENT_DMA_MMAP
745 bool
746
Zhaoxiu Zengfff7fb02016-05-20 17:03:57 -0700747config CPU_NO_EFFICIENT_FFS
748 def_bool n
749
Andy Lutomirskiba14a192016-08-11 02:35:21 -0700750config HAVE_ARCH_VMAP_STACK
751 def_bool n
752 help
753 An arch should select this symbol if it can support kernel stacks
754 in vmalloc space. This means:
755
756 - vmalloc space must be large enough to hold many kernel stacks.
757 This may rule out many 32-bit architectures.
758
759 - Stacks in vmalloc space need to work reliably. For example, if
760 vmap page tables are created on demand, either this mechanism
761 needs to work while the stack points to a virtual address with
762 unpopulated page tables or arch code (switch_to() and switch_mm(),
763 most likely) needs to ensure that the stack's page table entries
764 are populated before running on a possibly unpopulated stack.
765
766 - If the stack overflows into a guard page, something reasonable
767 should happen. The definition of "reasonable" is flexible, but
768 instantly rebooting without logging anything would be unfriendly.
769
770config VMAP_STACK
771 default y
772 bool "Use a virtually-mapped stack"
773 depends on HAVE_ARCH_VMAP_STACK && !KASAN
774 ---help---
775 Enable this if you want the use virtually-mapped kernel stacks
776 with guard pages. This causes kernel stack overflows to be
777 caught immediately rather than causing difficult-to-diagnose
778 corruption.
779
780 This is presently incompatible with KASAN because KASAN expects
781 the stack to map directly to the KASAN shadow map using a formula
782 that is incorrect if the stack is in vmalloc space.
783
Laura Abbottad21fc42017-02-06 16:31:57 -0800784config ARCH_OPTIONAL_KERNEL_RWX
785 def_bool n
786
787config ARCH_OPTIONAL_KERNEL_RWX_DEFAULT
788 def_bool n
789
790config ARCH_HAS_STRICT_KERNEL_RWX
791 def_bool n
792
793config DEBUG_RODATA
794 bool "Make kernel text and rodata read-only" if ARCH_OPTIONAL_KERNEL_RWX
795 depends on ARCH_HAS_STRICT_KERNEL_RWX
796 default !ARCH_OPTIONAL_KERNEL_RWX || ARCH_OPTIONAL_KERNEL_RWX_DEFAULT
797 help
798 If this is set, kernel text and rodata memory will be made read-only,
799 and non-text memory will be made non-executable. This provides
800 protection against certain security exploits (e.g. executing the heap
801 or modifying text)
802
803 These features are considered standard security practice these days.
804 You should say Y here in almost all cases.
805
806config ARCH_HAS_STRICT_MODULE_RWX
807 def_bool n
808
809config DEBUG_SET_MODULE_RONX
810 bool "Set loadable kernel module data as NX and text as RO" if ARCH_OPTIONAL_KERNEL_RWX
811 depends on ARCH_HAS_STRICT_MODULE_RWX && MODULES
812 default !ARCH_OPTIONAL_KERNEL_RWX || ARCH_OPTIONAL_KERNEL_RWX_DEFAULT
813 help
814 If this is set, module text and rodata memory will be made read-only,
815 and non-text memory will be made non-executable. This provides
816 protection against certain security exploits (e.g. writing to text)
817
Peter Oberparleiter2521f2c2009-06-17 16:28:08 -0700818source "kernel/gcov/Kconfig"