blob: 180ea33164dc45821a78c08043dc95119c1bdb7e [file] [log] [blame]
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
Mathieu Desnoyers125e5642008-02-02 15:10:36 -05008config OPROFILE
Robert Richterb309a292010-02-26 15:01:23 +01009 tristate "OProfile system profiling"
Mathieu Desnoyers125e5642008-02-02 15:10:36 -050010 depends on PROFILING
11 depends on HAVE_OPROFILE
Ingo Molnard69d59f2008-12-12 09:38:57 +010012 select RING_BUFFER
Christian Borntraeger9a5963e2009-09-16 21:56:49 +020013 select RING_BUFFER_ALLOW_SWAP
Mathieu Desnoyers125e5642008-02-02 15:10:36 -050014 help
15 OProfile is a profiling system capable of profiling the
16 whole system, include the kernel, kernel modules, libraries,
17 and applications.
18
19 If unsure, say N.
20
Jason Yeh4d4036e2009-07-08 13:49:38 +020021config OPROFILE_EVENT_MULTIPLEX
22 bool "OProfile multiplexing support (EXPERIMENTAL)"
23 default n
24 depends on OPROFILE && X86
25 help
26 The number of hardware counters is limited. The multiplexing
27 feature enables OProfile to gather more events than counters
28 are provided by the hardware. This is realized by switching
29 between events at an user specified time interval.
30
31 If unsure, say N.
32
Mathieu Desnoyers125e5642008-02-02 15:10:36 -050033config HAVE_OPROFILE
Jan Beulich9ba16082008-10-15 22:01:38 -070034 bool
Mathieu Desnoyers125e5642008-02-02 15:10:36 -050035
Robert Richterdcfce4a2011-10-11 17:11:08 +020036config OPROFILE_NMI_TIMER
37 def_bool y
Anton Blanchardaf9feeb2015-04-09 12:52:55 +100038 depends on PERF_EVENTS && HAVE_PERF_EVENTS_NMI && !PPC64
Robert Richterdcfce4a2011-10-11 17:11:08 +020039
Mathieu Desnoyers125e5642008-02-02 15:10:36 -050040config KPROBES
41 bool "Kprobes"
Masami Hiramatsu05ed1602010-09-13 19:25:41 +090042 depends on MODULES
Mathieu Desnoyers125e5642008-02-02 15:10:36 -050043 depends on HAVE_KPROBES
Masami Hiramatsu05ed1602010-09-13 19:25:41 +090044 select KALLSYMS
Mathieu Desnoyers125e5642008-02-02 15:10:36 -050045 help
46 Kprobes allows you to trap at almost any kernel address and
47 execute a callback function. register_kprobe() establishes
48 a probepoint and specifies the callback. Kprobes is useful
49 for kernel debugging, non-intrusive instrumentation and testing.
50 If in doubt, say "N".
51
Steven Rostedt45f81b12010-10-29 12:33:43 -040052config JUMP_LABEL
Ingo Molnarc5905af2012-02-24 08:31:31 +010053 bool "Optimize very unlikely/likely branches"
Steven Rostedt45f81b12010-10-29 12:33:43 -040054 depends on HAVE_ARCH_JUMP_LABEL
55 help
Ingo Molnarc5905af2012-02-24 08:31:31 +010056 This option enables a transparent branch optimization that
57 makes certain almost-always-true or almost-always-false branch
58 conditions even cheaper to execute within the kernel.
Steven Rostedt45f81b12010-10-29 12:33:43 -040059
Ingo Molnarc5905af2012-02-24 08:31:31 +010060 Certain performance-sensitive kernel code, such as trace points,
61 scheduler functionality, networking code and KVM have such
62 branches and include support for this optimization technique.
63
64 If it is detected that the compiler has support for "asm goto",
65 the kernel will compile such branches with just a nop
66 instruction. When the condition flag is toggled to true, the
67 nop will be converted to a jump instruction to execute the
68 conditional block of instructions.
69
70 This technique lowers overhead and stress on the branch prediction
71 of the processor and generally makes the kernel faster. The update
72 of the condition is slower, but those are always very rare.
73
74 ( On 32-bit x86, the necessary options added to the compiler
75 flags may increase the size of the kernel slightly. )
Steven Rostedt45f81b12010-10-29 12:33:43 -040076
Peter Zijlstra1987c942015-07-27 18:32:09 +020077config STATIC_KEYS_SELFTEST
78 bool "Static key selftest"
79 depends on JUMP_LABEL
80 help
81 Boot time self-test of the branch patching code.
82
Masami Hiramatsuafd66252010-02-25 08:34:07 -050083config OPTPROBES
Masami Hiramatsu5cc718b2010-03-15 13:00:54 -040084 def_bool y
85 depends on KPROBES && HAVE_OPTPROBES
Masami Hiramatsuafd66252010-02-25 08:34:07 -050086 depends on !PREEMPT
Masami Hiramatsuafd66252010-02-25 08:34:07 -050087
Masami Hiramatsue7dbfe32012-09-28 17:15:20 +090088config KPROBES_ON_FTRACE
89 def_bool y
90 depends on KPROBES && HAVE_KPROBES_ON_FTRACE
91 depends on DYNAMIC_FTRACE_WITH_REGS
92 help
93 If function tracer is enabled and the arch supports full
94 passing of pt_regs to function tracing, then kprobes can
95 optimize on top of function tracing.
96
Srikar Dronamraju2b144492012-02-09 14:56:42 +053097config UPROBES
David A. Long09294e32014-03-07 10:32:22 -050098 def_bool n
Srikar Dronamraju2b144492012-02-09 14:56:42 +053099 help
Ingo Molnar7b2d81d2012-02-17 09:27:41 +0100100 Uprobes is the user-space counterpart to kprobes: they
101 enable instrumentation applications (such as 'perf probe')
102 to establish unintrusive probes in user-space binaries and
103 libraries, by executing handler functions when the probes
104 are hit by user-space applications.
105
106 ( These probes come in the form of single-byte breakpoints,
107 managed by the kernel and kept transparent to the probed
108 application. )
Srikar Dronamraju2b144492012-02-09 14:56:42 +0530109
James Hoganc19fa942012-05-30 11:23:23 +0100110config HAVE_64BIT_ALIGNED_ACCESS
111 def_bool 64BIT && !HAVE_EFFICIENT_UNALIGNED_ACCESS
112 help
113 Some architectures require 64 bit accesses to be 64 bit
114 aligned, which also requires structs containing 64 bit values
115 to be 64 bit aligned too. This includes some 32 bit
116 architectures which can do 64 bit accesses, as well as 64 bit
117 architectures without unaligned access.
118
119 This symbol should be selected by an architecture if 64 bit
120 accesses are required to be 64 bit aligned in this way even
121 though it is not a 64 bit architecture.
122
123 See Documentation/unaligned-memory-access.txt for more
124 information on the topic of unaligned memory accesses.
125
Johannes Berg58340a02008-07-25 01:45:33 -0700126config HAVE_EFFICIENT_UNALIGNED_ACCESS
Jan Beulich9ba16082008-10-15 22:01:38 -0700127 bool
Johannes Berg58340a02008-07-25 01:45:33 -0700128 help
129 Some architectures are unable to perform unaligned accesses
130 without the use of get_unaligned/put_unaligned. Others are
131 unable to perform such accesses efficiently (e.g. trap on
132 unaligned access and require fixing it up in the exception
133 handler.)
134
135 This symbol should be selected by an architecture if it can
136 perform unaligned accesses efficiently to allow different
137 code paths to be selected for these cases. Some network
138 drivers, for example, could opt to not fix up alignment
139 problems with received packets if doing so would not help
140 much.
141
142 See Documentation/unaligned-memory-access.txt for more
143 information on the topic of unaligned memory accesses.
144
David Woodhousecf66bb92012-12-03 16:25:40 +0000145config ARCH_USE_BUILTIN_BSWAP
146 bool
147 help
148 Modern versions of GCC (since 4.4) have builtin functions
149 for handling byte-swapping. Using these, instead of the old
150 inline assembler that the architecture code provides in the
151 __arch_bswapXX() macros, allows the compiler to see what's
152 happening and offers more opportunity for optimisation. In
153 particular, the compiler will be able to combine the byteswap
154 with a nearby load or store and use load-and-swap or
155 store-and-swap instructions if the architecture has them. It
156 should almost *never* result in code which is worse than the
157 hand-coded assembler in <asm/swab.h>. But just in case it
158 does, the use of the builtins is optional.
159
160 Any architecture with load-and-swap or store-and-swap
161 instructions should set this. And it shouldn't hurt to set it
162 on architectures that don't have such instructions.
163
Ananth N Mavinakayanahalli9edddaa2008-03-04 14:28:37 -0800164config KRETPROBES
165 def_bool y
166 depends on KPROBES && HAVE_KRETPROBES
167
Avi Kivity7c68af62009-09-19 09:40:22 +0300168config USER_RETURN_NOTIFIER
169 bool
170 depends on HAVE_USER_RETURN_NOTIFIER
171 help
172 Provide a kernel-internal notification when a cpu is about to
173 switch to user mode.
174
Rik van Riel28b2ee22008-07-23 21:27:05 -0700175config HAVE_IOREMAP_PROT
Jan Beulich9ba16082008-10-15 22:01:38 -0700176 bool
Rik van Riel28b2ee22008-07-23 21:27:05 -0700177
Mathieu Desnoyers125e5642008-02-02 15:10:36 -0500178config HAVE_KPROBES
Jan Beulich9ba16082008-10-15 22:01:38 -0700179 bool
Ananth N Mavinakayanahalli9edddaa2008-03-04 14:28:37 -0800180
181config HAVE_KRETPROBES
Jan Beulich9ba16082008-10-15 22:01:38 -0700182 bool
Arthur Kepner74bc7ce2008-04-29 01:00:30 -0700183
Masami Hiramatsuafd66252010-02-25 08:34:07 -0500184config HAVE_OPTPROBES
185 bool
Cong Wangd314d742012-03-23 15:01:51 -0700186
Masami Hiramatsue7dbfe32012-09-28 17:15:20 +0900187config HAVE_KPROBES_ON_FTRACE
188 bool
189
Petr Mladek42a0bb32016-05-20 17:00:33 -0700190config HAVE_NMI
191 bool
192
Cong Wangd314d742012-03-23 15:01:51 -0700193config HAVE_NMI_WATCHDOG
Petr Mladek42a0bb32016-05-20 17:00:33 -0700194 depends on HAVE_NMI
Cong Wangd314d742012-03-23 15:01:51 -0700195 bool
Roland McGrath1f5a4ad2008-07-25 19:45:57 -0700196#
197# An arch should select this if it provides all these things:
198#
199# task_pt_regs() in asm/processor.h or asm/ptrace.h
200# arch_has_single_step() if there is hardware single-step support
201# arch_has_block_step() if there is hardware block-step support
Roland McGrath1f5a4ad2008-07-25 19:45:57 -0700202# asm/syscall.h supplying asm-generic/syscall.h interface
203# linux/regset.h user_regset interfaces
204# CORE_DUMP_USE_REGSET #define'd in linux/elf.h
205# TIF_SYSCALL_TRACE calls tracehook_report_syscall_{entry,exit}
206# TIF_NOTIFY_RESUME calls tracehook_notify_resume()
207# signal delivery calls tracehook_signal_handler()
208#
209config HAVE_ARCH_TRACEHOOK
Jan Beulich9ba16082008-10-15 22:01:38 -0700210 bool
Roland McGrath1f5a4ad2008-07-25 19:45:57 -0700211
Marek Szyprowskic64be2b2011-12-29 13:09:51 +0100212config HAVE_DMA_CONTIGUOUS
213 bool
214
Thomas Gleixner29d5e042012-04-20 13:05:45 +0000215config GENERIC_SMP_IDLE_THREAD
216 bool
217
Kevin Hilman485cf5d2013-04-24 17:19:13 -0700218config GENERIC_IDLE_POLL_SETUP
219 bool
220
Thomas Gleixnera6359d12012-05-03 09:03:02 +0000221# Select if arch init_task initializer is different to init/init_task.c
222config ARCH_INIT_TASK
Thomas Gleixnera4a2eb42012-05-03 09:02:48 +0000223 bool
224
Thomas Gleixnerf5e10282012-05-05 15:05:48 +0000225# Select if arch has its private alloc_task_struct() function
226config ARCH_TASK_STRUCT_ALLOCATOR
227 bool
228
Linus Torvaldsb235bee2016-06-24 15:09:37 -0700229# Select if arch has its private alloc_thread_stack() function
230config ARCH_THREAD_STACK_ALLOCATOR
Thomas Gleixnerf5e10282012-05-05 15:05:48 +0000231 bool
232
Ingo Molnar5aaeb5c2015-07-17 12:28:12 +0200233# Select if arch wants to size task_struct dynamically via arch_task_struct_size:
234config ARCH_WANTS_DYNAMIC_TASK_STRUCT
235 bool
236
Heiko Carstensf850c30c2010-02-10 17:25:17 +0100237config HAVE_REGS_AND_STACK_ACCESS_API
238 bool
Heiko Carstense01292b2010-02-18 14:25:21 +0100239 help
240 This symbol should be selected by an architecure if it supports
241 the API needed to access registers and stack entries from pt_regs,
242 declared in asm/ptrace.h
243 For example the kprobes-based event tracer needs this API.
Heiko Carstensf850c30c2010-02-10 17:25:17 +0100244
David Brownell9483a572008-07-23 21:26:48 -0700245config HAVE_CLK
Jan Beulich9ba16082008-10-15 22:01:38 -0700246 bool
David Brownell9483a572008-07-23 21:26:48 -0700247 help
248 The <linux/clk.h> calls support software clock gating and
249 thus are a key power management tool on many systems.
250
Joerg Roedel5ee00bd2009-01-09 12:14:24 +0100251config HAVE_DMA_API_DEBUG
252 bool
Heiko Carstens36cd3c92009-04-09 18:48:34 +0200253
K.Prasad62a038d2009-06-01 23:43:33 +0530254config HAVE_HW_BREAKPOINT
255 bool
Frederic Weisbecker99e8c5a2009-12-17 01:33:54 +0100256 depends on PERF_EVENTS
K.Prasad62a038d2009-06-01 23:43:33 +0530257
Frederic Weisbecker01027522010-04-11 18:55:56 +0200258config HAVE_MIXED_BREAKPOINTS_REGS
259 bool
260 depends on HAVE_HW_BREAKPOINT
261 help
262 Depending on the arch implementation of hardware breakpoints,
263 some of them have separate registers for data and instruction
264 breakpoints addresses, others have mixed registers to store
265 them but define the access type in a control register.
266 Select this option if your arch implements breakpoints under the
267 latter fashion.
268
Avi Kivity7c68af62009-09-19 09:40:22 +0300269config HAVE_USER_RETURN_NOTIFIER
270 bool
Ingo Molnara1922ed2009-09-07 08:19:51 +0200271
Frederic Weisbeckerc01d4322010-05-15 22:57:48 +0200272config HAVE_PERF_EVENTS_NMI
273 bool
Frederic Weisbecker23637d42010-05-15 23:15:20 +0200274 help
275 System hardware can generate an NMI using the perf event
276 subsystem. Also has support for calculating CPU cycle events
277 to determine how many clock cycles in a given period.
Frederic Weisbeckerc01d4322010-05-15 22:57:48 +0200278
Jiri Olsac5e63192012-08-07 15:20:36 +0200279config HAVE_PERF_REGS
280 bool
281 help
282 Support selective register dumps for perf events. This includes
283 bit-mapping of each registers and a unique architecture id.
284
Jiri Olsac5ebced2012-08-07 15:20:40 +0200285config HAVE_PERF_USER_STACK_DUMP
286 bool
287 help
288 Support user stack dumps for perf event samples. This needs
289 access to the user stack pointer which is not unified across
290 architectures.
291
Jason Baronbf5438fc2010-09-17 11:09:00 -0400292config HAVE_ARCH_JUMP_LABEL
293 bool
294
Peter Zijlstra26723912011-05-24 17:12:00 -0700295config HAVE_RCU_TABLE_FREE
296 bool
297
Huang Yingdf013ff2011-07-13 13:14:22 +0800298config ARCH_HAVE_NMI_SAFE_CMPXCHG
299 bool
300
Heiko Carstens43570fd2012-01-12 17:17:27 -0800301config HAVE_ALIGNED_STRUCT_PAGE
302 bool
303 help
304 This makes sure that struct pages are double word aligned and that
305 e.g. the SLUB allocator can perform double word atomic operations
306 on a struct page for better performance. However selecting this
307 might increase the size of a struct page by a word.
308
Heiko Carstens41561532012-01-12 17:17:30 -0800309config HAVE_CMPXCHG_LOCAL
310 bool
311
Heiko Carstens25654092012-01-12 17:17:33 -0800312config HAVE_CMPXCHG_DOUBLE
313 bool
314
Will Deaconc1d7e012012-07-30 14:42:46 -0700315config ARCH_WANT_IPC_PARSE_VERSION
316 bool
317
318config ARCH_WANT_COMPAT_IPC_PARSE_VERSION
319 bool
320
Chris Metcalf48b25c42012-03-15 13:13:38 -0400321config ARCH_WANT_OLD_COMPAT_IPC
Will Deaconc1d7e012012-07-30 14:42:46 -0700322 select ARCH_WANT_COMPAT_IPC_PARSE_VERSION
Chris Metcalf48b25c42012-03-15 13:13:38 -0400323 bool
324
Will Drewrye2cfabdf2012-04-12 16:47:57 -0500325config HAVE_ARCH_SECCOMP_FILTER
326 bool
327 help
Will Drewryfb0fadf2012-04-12 16:48:02 -0500328 An arch should select this symbol if it provides all of these things:
Will Drewrybb6ea432012-04-12 16:48:01 -0500329 - syscall_get_arch()
330 - syscall_get_arguments()
331 - syscall_rollback()
332 - syscall_set_return_value()
Will Drewryfb0fadf2012-04-12 16:48:02 -0500333 - SIGSYS siginfo_t support
334 - secure_computing is called from a ptrace_event()-safe context
335 - secure_computing return value is checked and a return value of -1
336 results in the system call being skipped immediately.
Kees Cook48dc92b2014-06-25 16:08:24 -0700337 - seccomp syscall wired up
Will Drewrye2cfabdf2012-04-12 16:47:57 -0500338
339config SECCOMP_FILTER
340 def_bool y
341 depends on HAVE_ARCH_SECCOMP_FILTER && SECCOMP && NET
342 help
343 Enable tasks to build secure computing environments defined
344 in terms of Berkeley Packet Filter programs which implement
345 task-defined system call filtering polices.
346
347 See Documentation/prctl/seccomp_filter.txt for details.
348
Emese Revfy6b90bd42016-05-24 00:09:38 +0200349config HAVE_GCC_PLUGINS
350 bool
351 help
352 An arch should select this symbol if it supports building with
353 GCC plugins.
354
355menuconfig GCC_PLUGINS
356 bool "GCC plugins"
357 depends on HAVE_GCC_PLUGINS
Kees Cooka519167e2016-06-11 09:09:28 -0700358 depends on !COMPILE_TEST
Emese Revfy6b90bd42016-05-24 00:09:38 +0200359 help
360 GCC plugins are loadable modules that provide extra features to the
361 compiler. They are useful for runtime instrumentation and static analysis.
362
363 See Documentation/gcc-plugins.txt for details.
364
Emese Revfy0dae7762016-05-24 00:10:35 +0200365config GCC_PLUGIN_CYC_COMPLEXITY
366 bool "Compute the cyclomatic complexity of a function"
367 depends on GCC_PLUGINS
368 help
369 The complexity M of a function's control flow graph is defined as:
370 M = E - N + 2P
371 where
372
373 E = the number of edges
374 N = the number of nodes
375 P = the number of connected components (exit nodes).
376
Emese Revfy543c37c2016-05-24 00:11:37 +0200377config GCC_PLUGIN_SANCOV
378 bool
379 depends on GCC_PLUGINS
380 help
381 This plugin inserts a __sanitizer_cov_trace_pc() call at the start of
382 basic blocks. It supports all gcc versions with plugin support (from
383 gcc-4.5 on). It is based on the commit "Add fuzzing coverage support"
384 by Dmitry Vyukov <dvyukov@google.com>.
385
Kees Cook19952a92013-12-19 11:35:58 -0800386config HAVE_CC_STACKPROTECTOR
387 bool
388 help
389 An arch should select this symbol if:
390 - its compiler supports the -fstack-protector option
391 - it has implemented a stack canary (e.g. __stack_chk_guard)
392
393config CC_STACKPROTECTOR
Kees Cook87796572013-12-19 11:35:59 -0800394 def_bool n
Kees Cook19952a92013-12-19 11:35:58 -0800395 help
Kees Cook87796572013-12-19 11:35:59 -0800396 Set when a stack-protector mode is enabled, so that the build
397 can enable kernel-side support for the GCC feature.
398
399choice
400 prompt "Stack Protector buffer overflow detection"
401 depends on HAVE_CC_STACKPROTECTOR
402 default CC_STACKPROTECTOR_NONE
403 help
404 This option turns on the "stack-protector" GCC feature. This
Kees Cook19952a92013-12-19 11:35:58 -0800405 feature puts, at the beginning of functions, a canary value on
406 the stack just before the return address, and validates
407 the value just before actually returning. Stack based buffer
408 overflows (that need to overwrite this return address) now also
409 overwrite the canary, which gets detected and the attack is then
410 neutralized via a kernel panic.
411
Kees Cook87796572013-12-19 11:35:59 -0800412config CC_STACKPROTECTOR_NONE
413 bool "None"
414 help
415 Disable "stack-protector" GCC feature.
416
417config CC_STACKPROTECTOR_REGULAR
418 bool "Regular"
419 select CC_STACKPROTECTOR
420 help
421 Functions will have the stack-protector canary logic added if they
422 have an 8-byte or larger character array on the stack.
423
Kees Cook19952a92013-12-19 11:35:58 -0800424 This feature requires gcc version 4.2 or above, or a distribution
Kees Cook87796572013-12-19 11:35:59 -0800425 gcc with the feature backported ("-fstack-protector").
426
427 On an x86 "defconfig" build, this feature adds canary checks to
428 about 3% of all kernel functions, which increases kernel code size
429 by about 0.3%.
430
431config CC_STACKPROTECTOR_STRONG
432 bool "Strong"
433 select CC_STACKPROTECTOR
434 help
435 Functions will have the stack-protector canary logic added in any
436 of the following conditions:
437
438 - local variable's address used as part of the right hand side of an
439 assignment or function argument
440 - local variable is an array (or union containing an array),
441 regardless of array type or length
442 - uses register local variables
443
444 This feature requires gcc version 4.9 or above, or a distribution
445 gcc with the feature backported ("-fstack-protector-strong").
446
447 On an x86 "defconfig" build, this feature adds canary checks to
448 about 20% of all kernel functions, which increases the kernel code
449 size by about 2%.
450
451endchoice
Kees Cook19952a92013-12-19 11:35:58 -0800452
Kees Cook0f60a8e2016-07-12 16:19:48 -0700453config HAVE_ARCH_WITHIN_STACK_FRAMES
454 bool
455 help
456 An architecture should select this if it can walk the kernel stack
457 frames to determine if an object is part of either the arguments
458 or local variables (i.e. that it excludes saved return addresses,
459 and similar) by implementing an inline arch_within_stack_frames(),
460 which is used by CONFIG_HARDENED_USERCOPY.
461
Frederic Weisbecker91d1aa432012-11-27 19:33:25 +0100462config HAVE_CONTEXT_TRACKING
Frederic Weisbecker2b1d5022012-07-11 20:26:30 +0200463 bool
464 help
Frederic Weisbecker91d1aa432012-11-27 19:33:25 +0100465 Provide kernel/user boundaries probes necessary for subsystems
466 that need it, such as userspace RCU extended quiescent state.
467 Syscalls need to be wrapped inside user_exit()-user_enter() through
468 the slow path using TIF_NOHZ flag. Exceptions handlers must be
469 wrapped as well. Irqs are already protected inside
470 rcu_irq_enter/rcu_irq_exit() but preemption or signal handling on
471 irq exit still need to be protected.
Frederic Weisbecker2b1d5022012-07-11 20:26:30 +0200472
Frederic Weisbeckerb9527412012-06-16 15:39:34 +0200473config HAVE_VIRT_CPU_ACCOUNTING
474 bool
475
Kevin Hilman554b0002013-09-16 15:28:21 -0700476config HAVE_VIRT_CPU_ACCOUNTING_GEN
477 bool
478 default y if 64BIT
479 help
480 With VIRT_CPU_ACCOUNTING_GEN, cputime_t becomes 64-bit.
481 Before enabling this option, arch code must be audited
482 to ensure there are no races in concurrent read/write of
483 cputime_t. For example, reading/writing 64-bit cputime_t on
484 some 32-bit arches may require multiple accesses, so proper
485 locking is needed to protect against concurrent accesses.
486
487
Frederic Weisbeckerfdf9c352012-09-09 14:56:31 +0200488config HAVE_IRQ_TIME_ACCOUNTING
489 bool
490 help
491 Archs need to ensure they use a high enough resolution clock to
492 support irq time accounting and then call enable_sched_clock_irqtime().
493
Gerald Schaefer15626062012-10-08 16:30:04 -0700494config HAVE_ARCH_TRANSPARENT_HUGEPAGE
495 bool
496
Toshi Kani0ddab1d2015-04-14 15:47:20 -0700497config HAVE_ARCH_HUGE_VMAP
498 bool
499
Pavel Emelyanov0f8975e2013-07-03 15:01:20 -0700500config HAVE_ARCH_SOFT_DIRTY
501 bool
502
David Howells786d35d2012-09-28 14:31:03 +0930503config HAVE_MOD_ARCH_SPECIFIC
504 bool
505 help
506 The arch uses struct mod_arch_specific to store data. Many arches
507 just need a simple module loader without arch specific data - those
508 should not enable this.
509
510config MODULES_USE_ELF_RELA
511 bool
512 help
513 Modules only use ELF RELA relocations. Modules with ELF REL
514 relocations will give an error.
515
516config MODULES_USE_ELF_REL
517 bool
518 help
519 Modules only use ELF REL relocations. Modules with ELF RELA
520 relocations will give an error.
521
Rusty Russellb92021b2013-03-15 15:04:17 +1030522config HAVE_UNDERSCORE_SYMBOL_PREFIX
523 bool
524 help
525 Some architectures generate an _ in front of C symbols; things like
526 module loading and assembly files need to know about this.
527
Frederic Weisbeckercc1f0272013-09-24 17:17:47 +0200528config HAVE_IRQ_EXIT_ON_IRQ_STACK
529 bool
530 help
531 Architecture doesn't only execute the irq handler on the irq stack
532 but also irq_exit(). This way we can process softirqs on this irq
533 stack instead of switching to a new one when we call __do_softirq()
534 in the end of an hardirq.
535 This spares a stack switch and improves cache usage on softirq
536 processing.
537
Kirill A. Shutemov235a8f02015-04-14 15:46:17 -0700538config PGTABLE_LEVELS
539 int
540 default 2
541
Kees Cook2b68f6c2015-04-14 15:48:00 -0700542config ARCH_HAS_ELF_RANDOMIZE
543 bool
544 help
545 An architecture supports choosing randomized locations for
546 stack, mmap, brk, and ET_DYN. Defined functions:
547 - arch_mmap_rnd()
Kees Cook204db6e2015-04-14 15:48:12 -0700548 - arch_randomize_brk()
Kees Cook2b68f6c2015-04-14 15:48:00 -0700549
Daniel Cashmand07e2252016-01-14 15:19:53 -0800550config HAVE_ARCH_MMAP_RND_BITS
551 bool
552 help
553 An arch should select this symbol if it supports setting a variable
554 number of bits for use in establishing the base address for mmap
555 allocations, has MMU enabled and provides values for both:
556 - ARCH_MMAP_RND_BITS_MIN
557 - ARCH_MMAP_RND_BITS_MAX
558
Jiri Slaby5f56a5d2016-05-20 17:00:16 -0700559config HAVE_EXIT_THREAD
560 bool
561 help
562 An architecture implements exit_thread.
563
Daniel Cashmand07e2252016-01-14 15:19:53 -0800564config ARCH_MMAP_RND_BITS_MIN
565 int
566
567config ARCH_MMAP_RND_BITS_MAX
568 int
569
570config ARCH_MMAP_RND_BITS_DEFAULT
571 int
572
573config ARCH_MMAP_RND_BITS
574 int "Number of bits to use for ASLR of mmap base address" if EXPERT
575 range ARCH_MMAP_RND_BITS_MIN ARCH_MMAP_RND_BITS_MAX
576 default ARCH_MMAP_RND_BITS_DEFAULT if ARCH_MMAP_RND_BITS_DEFAULT
577 default ARCH_MMAP_RND_BITS_MIN
578 depends on HAVE_ARCH_MMAP_RND_BITS
579 help
580 This value can be used to select the number of bits to use to
581 determine the random offset to the base address of vma regions
582 resulting from mmap allocations. This value will be bounded
583 by the architecture's minimum and maximum supported values.
584
585 This value can be changed after boot using the
586 /proc/sys/vm/mmap_rnd_bits tunable
587
588config HAVE_ARCH_MMAP_RND_COMPAT_BITS
589 bool
590 help
591 An arch should select this symbol if it supports running applications
592 in compatibility mode, supports setting a variable number of bits for
593 use in establishing the base address for mmap allocations, has MMU
594 enabled and provides values for both:
595 - ARCH_MMAP_RND_COMPAT_BITS_MIN
596 - ARCH_MMAP_RND_COMPAT_BITS_MAX
597
598config ARCH_MMAP_RND_COMPAT_BITS_MIN
599 int
600
601config ARCH_MMAP_RND_COMPAT_BITS_MAX
602 int
603
604config ARCH_MMAP_RND_COMPAT_BITS_DEFAULT
605 int
606
607config ARCH_MMAP_RND_COMPAT_BITS
608 int "Number of bits to use for ASLR of mmap base address for compatible applications" if EXPERT
609 range ARCH_MMAP_RND_COMPAT_BITS_MIN ARCH_MMAP_RND_COMPAT_BITS_MAX
610 default ARCH_MMAP_RND_COMPAT_BITS_DEFAULT if ARCH_MMAP_RND_COMPAT_BITS_DEFAULT
611 default ARCH_MMAP_RND_COMPAT_BITS_MIN
612 depends on HAVE_ARCH_MMAP_RND_COMPAT_BITS
613 help
614 This value can be used to select the number of bits to use to
615 determine the random offset to the base address of vma regions
616 resulting from mmap allocations for compatible applications This
617 value will be bounded by the architecture's minimum and maximum
618 supported values.
619
620 This value can be changed after boot using the
621 /proc/sys/vm/mmap_rnd_compat_bits tunable
622
Josh Triplett3033f14a2015-06-25 15:01:19 -0700623config HAVE_COPY_THREAD_TLS
624 bool
625 help
626 Architecture provides copy_thread_tls to accept tls argument via
627 normal C parameter passing, rather than extracting the syscall
628 argument from pt_regs.
629
Josh Poimboeufb9ab5eb2016-02-28 22:22:42 -0600630config HAVE_STACK_VALIDATION
631 bool
632 help
633 Architecture supports the 'objtool check' host tool command, which
634 performs compile-time stack metadata validation.
635
George Spelvin468a9422016-05-26 22:11:51 -0400636config HAVE_ARCH_HASH
637 bool
638 default n
639 help
640 If this is set, the architecture provides an <asm/hash.h>
641 file which provides platform-specific implementations of some
642 functions in <linux/hash.h> or fs/namei.c.
643
William Breathitt Gray3a495512016-05-27 18:08:27 -0400644config ISA_BUS_API
645 def_bool ISA
646
Al Virod2125042012-10-23 13:17:59 -0400647#
648# ABI hall of shame
649#
650config CLONE_BACKWARDS
651 bool
652 help
653 Architecture has tls passed as the 4th argument of clone(2),
654 not the 5th one.
655
656config CLONE_BACKWARDS2
657 bool
658 help
659 Architecture has the first two arguments of clone(2) swapped.
660
Michal Simekdfa97712013-08-13 16:00:53 -0700661config CLONE_BACKWARDS3
662 bool
663 help
664 Architecture has tls passed as the 3rd argument of clone(2),
665 not the 5th one.
666
Al Viroeaca6ea2012-11-25 23:12:10 -0500667config ODD_RT_SIGACTION
668 bool
669 help
670 Architecture has unusual rt_sigaction(2) arguments
671
Al Viro0a0e8cd2012-12-25 16:04:12 -0500672config OLD_SIGSUSPEND
673 bool
674 help
675 Architecture has old sigsuspend(2) syscall, of one-argument variety
676
677config OLD_SIGSUSPEND3
678 bool
679 help
680 Even weirder antique ABI - three-argument sigsuspend(2)
681
Al Viro495dfbf2012-12-25 19:09:45 -0500682config OLD_SIGACTION
683 bool
684 help
685 Architecture has old sigaction(2) syscall. Nope, not the same
686 as OLD_SIGSUSPEND | OLD_SIGSUSPEND3 - alpha has sigsuspend(2),
687 but fairly different variant of sigaction(2), thanks to OSF/1
688 compatibility...
689
690config COMPAT_OLD_SIGACTION
691 bool
692
Christoph Hellwig0d4a6192016-01-20 15:01:22 -0800693config ARCH_NO_COHERENT_DMA_MMAP
694 bool
695
Zhaoxiu Zengfff7fb02016-05-20 17:03:57 -0700696config CPU_NO_EFFICIENT_FFS
697 def_bool n
698
Andy Lutomirskiba14a192016-08-11 02:35:21 -0700699config HAVE_ARCH_VMAP_STACK
700 def_bool n
701 help
702 An arch should select this symbol if it can support kernel stacks
703 in vmalloc space. This means:
704
705 - vmalloc space must be large enough to hold many kernel stacks.
706 This may rule out many 32-bit architectures.
707
708 - Stacks in vmalloc space need to work reliably. For example, if
709 vmap page tables are created on demand, either this mechanism
710 needs to work while the stack points to a virtual address with
711 unpopulated page tables or arch code (switch_to() and switch_mm(),
712 most likely) needs to ensure that the stack's page table entries
713 are populated before running on a possibly unpopulated stack.
714
715 - If the stack overflows into a guard page, something reasonable
716 should happen. The definition of "reasonable" is flexible, but
717 instantly rebooting without logging anything would be unfriendly.
718
719config VMAP_STACK
720 default y
721 bool "Use a virtually-mapped stack"
722 depends on HAVE_ARCH_VMAP_STACK && !KASAN
723 ---help---
724 Enable this if you want the use virtually-mapped kernel stacks
725 with guard pages. This causes kernel stack overflows to be
726 caught immediately rather than causing difficult-to-diagnose
727 corruption.
728
729 This is presently incompatible with KASAN because KASAN expects
730 the stack to map directly to the KASAN shadow map using a formula
731 that is incorrect if the stack is in vmalloc space.
732
Peter Oberparleiter2521f2c2009-06-17 16:28:08 -0700733source "kernel/gcov/Kconfig"