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Commit | Line | Data |
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fb32e03f MD |
1 | # |
2 | # General architecture dependent options | |
3 | # | |
125e5645 | 4 | |
2965faa5 DY |
5 | config KEXEC_CORE |
6 | bool | |
7 | ||
125e5645 | 8 | config OPROFILE |
b309a294 | 9 | tristate "OProfile system profiling" |
125e5645 MD |
10 | depends on PROFILING |
11 | depends on HAVE_OPROFILE | |
d69d59f4 | 12 | select RING_BUFFER |
9a5963eb | 13 | select RING_BUFFER_ALLOW_SWAP |
125e5645 MD |
14 | 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 | ||
4d4036e0 JY |
21 | config 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 | ||
125e5645 | 33 | config HAVE_OPROFILE |
9ba16087 | 34 | bool |
125e5645 | 35 | |
dcfce4a0 RR |
36 | config OPROFILE_NMI_TIMER |
37 | def_bool y | |
af9feebe | 38 | depends on PERF_EVENTS && HAVE_PERF_EVENTS_NMI && !PPC64 |
dcfce4a0 | 39 | |
125e5645 MD |
40 | config KPROBES |
41 | bool "Kprobes" | |
05ed160e | 42 | depends on MODULES |
125e5645 | 43 | depends on HAVE_KPROBES |
05ed160e | 44 | select KALLSYMS |
125e5645 MD |
45 | 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 | ||
45f81b1c | 52 | config JUMP_LABEL |
c5905afb | 53 | bool "Optimize very unlikely/likely branches" |
45f81b1c SR |
54 | depends on HAVE_ARCH_JUMP_LABEL |
55 | help | |
c5905afb IM |
56 | 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. | |
59 | ||
60 | 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 | ||
45f81b1c | 64 | If it is detected that the compiler has support for "asm goto", |
c5905afb IM |
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. | |
45f81b1c | 73 | |
c5905afb IM |
74 | ( On 32-bit x86, the necessary options added to the compiler |
75 | flags may increase the size of the kernel slightly. ) | |
45f81b1c | 76 | |
1987c947 PZ |
77 | config 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 | ||
afd66255 | 83 | config OPTPROBES |
5cc718b9 MH |
84 | def_bool y |
85 | depends on KPROBES && HAVE_OPTPROBES | |
afd66255 | 86 | depends on !PREEMPT |
afd66255 | 87 | |
e7dbfe34 MH |
88 | config 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 | ||
2b144498 | 97 | config UPROBES |
09294e31 | 98 | def_bool n |
2b144498 | 99 | help |
7b2d81d4 IM |
100 | 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. ) | |
2b144498 | 109 | |
c19fa94a JH |
110 | config 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 | ||
58340a07 | 126 | config HAVE_EFFICIENT_UNALIGNED_ACCESS |
9ba16087 | 127 | bool |
58340a07 JB |
128 | 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 | ||
cf66bb93 DW |
145 | config 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 | ||
9edddaa2 AM |
164 | config KRETPROBES |
165 | def_bool y | |
166 | depends on KPROBES && HAVE_KRETPROBES | |
167 | ||
7c68af6e AK |
168 | config 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 | ||
28b2ee20 | 175 | config HAVE_IOREMAP_PROT |
9ba16087 | 176 | bool |
28b2ee20 | 177 | |
125e5645 | 178 | config HAVE_KPROBES |
9ba16087 | 179 | bool |
9edddaa2 AM |
180 | |
181 | config HAVE_KRETPROBES | |
9ba16087 | 182 | bool |
74bc7cee | 183 | |
afd66255 MH |
184 | config HAVE_OPTPROBES |
185 | bool | |
d314d74c | 186 | |
e7dbfe34 MH |
187 | config HAVE_KPROBES_ON_FTRACE |
188 | bool | |
189 | ||
42a0bb3f PM |
190 | config HAVE_NMI |
191 | bool | |
192 | ||
d314d74c | 193 | config HAVE_NMI_WATCHDOG |
42a0bb3f | 194 | depends on HAVE_NMI |
d314d74c | 195 | bool |
1f5a4ad9 RM |
196 | # |
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 | |
1f5a4ad9 RM |
202 | # 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 | # | |
209 | config HAVE_ARCH_TRACEHOOK | |
9ba16087 | 210 | bool |
1f5a4ad9 | 211 | |
c64be2bb MS |
212 | config HAVE_DMA_CONTIGUOUS |
213 | bool | |
214 | ||
29d5e047 TG |
215 | config GENERIC_SMP_IDLE_THREAD |
216 | bool | |
217 | ||
485cf5da KH |
218 | config GENERIC_IDLE_POLL_SETUP |
219 | bool | |
220 | ||
a6359d1e TG |
221 | # Select if arch init_task initializer is different to init/init_task.c |
222 | config ARCH_INIT_TASK | |
a4a2eb49 TG |
223 | bool |
224 | ||
f5e10287 TG |
225 | # Select if arch has its private alloc_task_struct() function |
226 | config ARCH_TASK_STRUCT_ALLOCATOR | |
227 | bool | |
228 | ||
b235beea LT |
229 | # Select if arch has its private alloc_thread_stack() function |
230 | config ARCH_THREAD_STACK_ALLOCATOR | |
f5e10287 TG |
231 | bool |
232 | ||
5aaeb5c0 IM |
233 | # Select if arch wants to size task_struct dynamically via arch_task_struct_size: |
234 | config ARCH_WANTS_DYNAMIC_TASK_STRUCT | |
235 | bool | |
236 | ||
f850c30c HC |
237 | config HAVE_REGS_AND_STACK_ACCESS_API |
238 | bool | |
e01292b1 HC |
239 | 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. | |
f850c30c | 244 | |
9483a578 | 245 | config HAVE_CLK |
9ba16087 | 246 | bool |
9483a578 DB |
247 | help |
248 | The <linux/clk.h> calls support software clock gating and | |
249 | thus are a key power management tool on many systems. | |
250 | ||
5ee00bd4 JR |
251 | config HAVE_DMA_API_DEBUG |
252 | bool | |
36cd3c9f | 253 | |
62a038d3 P |
254 | config HAVE_HW_BREAKPOINT |
255 | bool | |
99e8c5a3 | 256 | depends on PERF_EVENTS |
62a038d3 | 257 | |
0102752e FW |
258 | config 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 | ||
7c68af6e AK |
269 | config HAVE_USER_RETURN_NOTIFIER |
270 | bool | |
a1922ed6 | 271 | |
c01d4323 FW |
272 | config HAVE_PERF_EVENTS_NMI |
273 | bool | |
23637d47 FW |
274 | 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. | |
c01d4323 | 278 | |
c5e63197 JO |
279 | config 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 | ||
c5ebcedb JO |
285 | config 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 | ||
bf5438fc JB |
292 | config HAVE_ARCH_JUMP_LABEL |
293 | bool | |
294 | ||
26723911 PZ |
295 | config HAVE_RCU_TABLE_FREE |
296 | bool | |
297 | ||
df013ffb HY |
298 | config ARCH_HAVE_NMI_SAFE_CMPXCHG |
299 | bool | |
300 | ||
43570fd2 HC |
301 | config 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 | ||
4156153c HC |
309 | config HAVE_CMPXCHG_LOCAL |
310 | bool | |
311 | ||
2565409f HC |
312 | config HAVE_CMPXCHG_DOUBLE |
313 | bool | |
314 | ||
c1d7e01d WD |
315 | config ARCH_WANT_IPC_PARSE_VERSION |
316 | bool | |
317 | ||
318 | config ARCH_WANT_COMPAT_IPC_PARSE_VERSION | |
319 | bool | |
320 | ||
48b25c43 | 321 | config ARCH_WANT_OLD_COMPAT_IPC |
c1d7e01d | 322 | select ARCH_WANT_COMPAT_IPC_PARSE_VERSION |
48b25c43 CM |
323 | bool |
324 | ||
e2cfabdf WD |
325 | config HAVE_ARCH_SECCOMP_FILTER |
326 | bool | |
327 | help | |
fb0fadf9 | 328 | An arch should select this symbol if it provides all of these things: |
bb6ea430 WD |
329 | - syscall_get_arch() |
330 | - syscall_get_arguments() | |
331 | - syscall_rollback() | |
332 | - syscall_set_return_value() | |
fb0fadf9 WD |
333 | - 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. | |
48dc92b9 | 337 | - seccomp syscall wired up |
e2cfabdf WD |
338 | |
339 | config 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 | ||
6b90bd4b ER |
349 | config HAVE_GCC_PLUGINS |
350 | bool | |
351 | help | |
352 | An arch should select this symbol if it supports building with | |
353 | GCC plugins. | |
354 | ||
355 | menuconfig GCC_PLUGINS | |
356 | bool "GCC plugins" | |
357 | depends on HAVE_GCC_PLUGINS | |
a519167e | 358 | depends on !COMPILE_TEST |
6b90bd4b ER |
359 | 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 | ||
0dae776c | 365 | config GCC_PLUGIN_CYC_COMPLEXITY |
215e2aa6 | 366 | bool "Compute the cyclomatic complexity of a function" if EXPERT |
0dae776c | 367 | depends on GCC_PLUGINS |
215e2aa6 | 368 | depends on !COMPILE_TEST |
0dae776c ER |
369 | help |
370 | The complexity M of a function's control flow graph is defined as: | |
371 | M = E - N + 2P | |
372 | where | |
373 | ||
374 | E = the number of edges | |
375 | N = the number of nodes | |
376 | P = the number of connected components (exit nodes). | |
377 | ||
215e2aa6 KC |
378 | Enabling this plugin reports the complexity to stderr during the |
379 | build. It mainly serves as a simple example of how to create a | |
380 | gcc plugin for the kernel. | |
381 | ||
543c37cb ER |
382 | config GCC_PLUGIN_SANCOV |
383 | bool | |
384 | depends on GCC_PLUGINS | |
385 | help | |
386 | This plugin inserts a __sanitizer_cov_trace_pc() call at the start of | |
387 | basic blocks. It supports all gcc versions with plugin support (from | |
388 | gcc-4.5 on). It is based on the commit "Add fuzzing coverage support" | |
389 | by Dmitry Vyukov <dvyukov@google.com>. | |
390 | ||
38addce8 ER |
391 | config GCC_PLUGIN_LATENT_ENTROPY |
392 | bool "Generate some entropy during boot and runtime" | |
393 | depends on GCC_PLUGINS | |
394 | help | |
395 | By saying Y here the kernel will instrument some kernel code to | |
396 | extract some entropy from both original and artificially created | |
397 | program state. This will help especially embedded systems where | |
398 | there is little 'natural' source of entropy normally. The cost | |
399 | is some slowdown of the boot process (about 0.5%) and fork and | |
400 | irq processing. | |
401 | ||
402 | Note that entropy extracted this way is not cryptographically | |
403 | secure! | |
404 | ||
405 | This plugin was ported from grsecurity/PaX. More information at: | |
406 | * https://grsecurity.net/ | |
407 | * https://pax.grsecurity.net/ | |
408 | ||
19952a92 KC |
409 | config HAVE_CC_STACKPROTECTOR |
410 | bool | |
411 | help | |
412 | An arch should select this symbol if: | |
413 | - its compiler supports the -fstack-protector option | |
414 | - it has implemented a stack canary (e.g. __stack_chk_guard) | |
415 | ||
416 | config CC_STACKPROTECTOR | |
8779657d KC |
417 | def_bool n |
418 | help | |
419 | Set when a stack-protector mode is enabled, so that the build | |
420 | can enable kernel-side support for the GCC feature. | |
421 | ||
422 | choice | |
423 | prompt "Stack Protector buffer overflow detection" | |
19952a92 | 424 | depends on HAVE_CC_STACKPROTECTOR |
8779657d | 425 | default CC_STACKPROTECTOR_NONE |
19952a92 | 426 | help |
8779657d | 427 | This option turns on the "stack-protector" GCC feature. This |
19952a92 KC |
428 | feature puts, at the beginning of functions, a canary value on |
429 | the stack just before the return address, and validates | |
430 | the value just before actually returning. Stack based buffer | |
431 | overflows (that need to overwrite this return address) now also | |
432 | overwrite the canary, which gets detected and the attack is then | |
433 | neutralized via a kernel panic. | |
434 | ||
8779657d KC |
435 | config CC_STACKPROTECTOR_NONE |
436 | bool "None" | |
437 | help | |
438 | Disable "stack-protector" GCC feature. | |
439 | ||
440 | config CC_STACKPROTECTOR_REGULAR | |
441 | bool "Regular" | |
442 | select CC_STACKPROTECTOR | |
443 | help | |
444 | Functions will have the stack-protector canary logic added if they | |
445 | have an 8-byte or larger character array on the stack. | |
446 | ||
19952a92 | 447 | This feature requires gcc version 4.2 or above, or a distribution |
8779657d KC |
448 | gcc with the feature backported ("-fstack-protector"). |
449 | ||
450 | On an x86 "defconfig" build, this feature adds canary checks to | |
451 | about 3% of all kernel functions, which increases kernel code size | |
452 | by about 0.3%. | |
453 | ||
454 | config CC_STACKPROTECTOR_STRONG | |
455 | bool "Strong" | |
456 | select CC_STACKPROTECTOR | |
457 | help | |
458 | Functions will have the stack-protector canary logic added in any | |
459 | of the following conditions: | |
460 | ||
461 | - local variable's address used as part of the right hand side of an | |
462 | assignment or function argument | |
463 | - local variable is an array (or union containing an array), | |
464 | regardless of array type or length | |
465 | - uses register local variables | |
466 | ||
467 | This feature requires gcc version 4.9 or above, or a distribution | |
468 | gcc with the feature backported ("-fstack-protector-strong"). | |
469 | ||
470 | On an x86 "defconfig" build, this feature adds canary checks to | |
471 | about 20% of all kernel functions, which increases the kernel code | |
472 | size by about 2%. | |
473 | ||
474 | endchoice | |
19952a92 | 475 | |
a5967db9 SR |
476 | config THIN_ARCHIVES |
477 | bool | |
478 | help | |
479 | Select this if the architecture wants to use thin archives | |
480 | instead of ld -r to create the built-in.o files. | |
481 | ||
b67067f1 NP |
482 | config LD_DEAD_CODE_DATA_ELIMINATION |
483 | bool | |
484 | help | |
485 | Select this if the architecture wants to do dead code and | |
486 | data elimination with the linker by compiling with | |
487 | -ffunction-sections -fdata-sections and linking with | |
488 | --gc-sections. | |
489 | ||
490 | This requires that the arch annotates or otherwise protects | |
491 | its external entry points from being discarded. Linker scripts | |
492 | must also merge .text.*, .data.*, and .bss.* correctly into | |
0f4c4af0 NP |
493 | output sections. Care must be taken not to pull in unrelated |
494 | sections (e.g., '.text.init'). Typically '.' in section names | |
495 | is used to distinguish them from label names / C identifiers. | |
b67067f1 | 496 | |
0f60a8ef KC |
497 | config HAVE_ARCH_WITHIN_STACK_FRAMES |
498 | bool | |
499 | help | |
500 | An architecture should select this if it can walk the kernel stack | |
501 | frames to determine if an object is part of either the arguments | |
502 | or local variables (i.e. that it excludes saved return addresses, | |
503 | and similar) by implementing an inline arch_within_stack_frames(), | |
504 | which is used by CONFIG_HARDENED_USERCOPY. | |
505 | ||
91d1aa43 | 506 | config HAVE_CONTEXT_TRACKING |
2b1d5024 FW |
507 | bool |
508 | help | |
91d1aa43 FW |
509 | Provide kernel/user boundaries probes necessary for subsystems |
510 | that need it, such as userspace RCU extended quiescent state. | |
511 | Syscalls need to be wrapped inside user_exit()-user_enter() through | |
512 | the slow path using TIF_NOHZ flag. Exceptions handlers must be | |
513 | wrapped as well. Irqs are already protected inside | |
514 | rcu_irq_enter/rcu_irq_exit() but preemption or signal handling on | |
515 | irq exit still need to be protected. | |
2b1d5024 | 516 | |
b952741c FW |
517 | config HAVE_VIRT_CPU_ACCOUNTING |
518 | bool | |
519 | ||
554b0004 KH |
520 | config HAVE_VIRT_CPU_ACCOUNTING_GEN |
521 | bool | |
522 | default y if 64BIT | |
523 | help | |
524 | With VIRT_CPU_ACCOUNTING_GEN, cputime_t becomes 64-bit. | |
525 | Before enabling this option, arch code must be audited | |
526 | to ensure there are no races in concurrent read/write of | |
527 | cputime_t. For example, reading/writing 64-bit cputime_t on | |
528 | some 32-bit arches may require multiple accesses, so proper | |
529 | locking is needed to protect against concurrent accesses. | |
530 | ||
531 | ||
fdf9c356 FW |
532 | config HAVE_IRQ_TIME_ACCOUNTING |
533 | bool | |
534 | help | |
535 | Archs need to ensure they use a high enough resolution clock to | |
536 | support irq time accounting and then call enable_sched_clock_irqtime(). | |
537 | ||
15626062 GS |
538 | config HAVE_ARCH_TRANSPARENT_HUGEPAGE |
539 | bool | |
540 | ||
0ddab1d2 TK |
541 | config HAVE_ARCH_HUGE_VMAP |
542 | bool | |
543 | ||
0f8975ec PE |
544 | config HAVE_ARCH_SOFT_DIRTY |
545 | bool | |
546 | ||
786d35d4 DH |
547 | config HAVE_MOD_ARCH_SPECIFIC |
548 | bool | |
549 | help | |
550 | The arch uses struct mod_arch_specific to store data. Many arches | |
551 | just need a simple module loader without arch specific data - those | |
552 | should not enable this. | |
553 | ||
554 | config MODULES_USE_ELF_RELA | |
555 | bool | |
556 | help | |
557 | Modules only use ELF RELA relocations. Modules with ELF REL | |
558 | relocations will give an error. | |
559 | ||
560 | config MODULES_USE_ELF_REL | |
561 | bool | |
562 | help | |
563 | Modules only use ELF REL relocations. Modules with ELF RELA | |
564 | relocations will give an error. | |
565 | ||
b92021b0 RR |
566 | config HAVE_UNDERSCORE_SYMBOL_PREFIX |
567 | bool | |
568 | help | |
569 | Some architectures generate an _ in front of C symbols; things like | |
570 | module loading and assembly files need to know about this. | |
571 | ||
cc1f0274 FW |
572 | config HAVE_IRQ_EXIT_ON_IRQ_STACK |
573 | bool | |
574 | help | |
575 | Architecture doesn't only execute the irq handler on the irq stack | |
576 | but also irq_exit(). This way we can process softirqs on this irq | |
577 | stack instead of switching to a new one when we call __do_softirq() | |
578 | in the end of an hardirq. | |
579 | This spares a stack switch and improves cache usage on softirq | |
580 | processing. | |
581 | ||
235a8f02 KS |
582 | config PGTABLE_LEVELS |
583 | int | |
584 | default 2 | |
585 | ||
2b68f6ca KC |
586 | config ARCH_HAS_ELF_RANDOMIZE |
587 | bool | |
588 | help | |
589 | An architecture supports choosing randomized locations for | |
590 | stack, mmap, brk, and ET_DYN. Defined functions: | |
591 | - arch_mmap_rnd() | |
204db6ed | 592 | - arch_randomize_brk() |
2b68f6ca | 593 | |
d07e2259 DC |
594 | config HAVE_ARCH_MMAP_RND_BITS |
595 | bool | |
596 | help | |
597 | An arch should select this symbol if it supports setting a variable | |
598 | number of bits for use in establishing the base address for mmap | |
599 | allocations, has MMU enabled and provides values for both: | |
600 | - ARCH_MMAP_RND_BITS_MIN | |
601 | - ARCH_MMAP_RND_BITS_MAX | |
602 | ||
5f56a5df JS |
603 | config HAVE_EXIT_THREAD |
604 | bool | |
605 | help | |
606 | An architecture implements exit_thread. | |
607 | ||
d07e2259 DC |
608 | config ARCH_MMAP_RND_BITS_MIN |
609 | int | |
610 | ||
611 | config ARCH_MMAP_RND_BITS_MAX | |
612 | int | |
613 | ||
614 | config ARCH_MMAP_RND_BITS_DEFAULT | |
615 | int | |
616 | ||
617 | config ARCH_MMAP_RND_BITS | |
618 | int "Number of bits to use for ASLR of mmap base address" if EXPERT | |
619 | range ARCH_MMAP_RND_BITS_MIN ARCH_MMAP_RND_BITS_MAX | |
620 | default ARCH_MMAP_RND_BITS_DEFAULT if ARCH_MMAP_RND_BITS_DEFAULT | |
621 | default ARCH_MMAP_RND_BITS_MIN | |
622 | depends on HAVE_ARCH_MMAP_RND_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. This value will be bounded | |
627 | by the architecture's minimum and maximum supported values. | |
628 | ||
629 | This value can be changed after boot using the | |
630 | /proc/sys/vm/mmap_rnd_bits tunable | |
631 | ||
632 | config HAVE_ARCH_MMAP_RND_COMPAT_BITS | |
633 | bool | |
634 | help | |
635 | An arch should select this symbol if it supports running applications | |
636 | in compatibility mode, supports setting a variable number of bits for | |
637 | use in establishing the base address for mmap allocations, has MMU | |
638 | enabled and provides values for both: | |
639 | - ARCH_MMAP_RND_COMPAT_BITS_MIN | |
640 | - ARCH_MMAP_RND_COMPAT_BITS_MAX | |
641 | ||
642 | config ARCH_MMAP_RND_COMPAT_BITS_MIN | |
643 | int | |
644 | ||
645 | config ARCH_MMAP_RND_COMPAT_BITS_MAX | |
646 | int | |
647 | ||
648 | config ARCH_MMAP_RND_COMPAT_BITS_DEFAULT | |
649 | int | |
650 | ||
651 | config ARCH_MMAP_RND_COMPAT_BITS | |
652 | int "Number of bits to use for ASLR of mmap base address for compatible applications" if EXPERT | |
653 | range ARCH_MMAP_RND_COMPAT_BITS_MIN ARCH_MMAP_RND_COMPAT_BITS_MAX | |
654 | default ARCH_MMAP_RND_COMPAT_BITS_DEFAULT if ARCH_MMAP_RND_COMPAT_BITS_DEFAULT | |
655 | default ARCH_MMAP_RND_COMPAT_BITS_MIN | |
656 | depends on HAVE_ARCH_MMAP_RND_COMPAT_BITS | |
657 | help | |
658 | This value can be used to select the number of bits to use to | |
659 | determine the random offset to the base address of vma regions | |
660 | resulting from mmap allocations for compatible applications This | |
661 | value will be bounded by the architecture's minimum and maximum | |
662 | supported values. | |
663 | ||
664 | This value can be changed after boot using the | |
665 | /proc/sys/vm/mmap_rnd_compat_bits tunable | |
666 | ||
3033f14a JT |
667 | config HAVE_COPY_THREAD_TLS |
668 | bool | |
669 | help | |
670 | Architecture provides copy_thread_tls to accept tls argument via | |
671 | normal C parameter passing, rather than extracting the syscall | |
672 | argument from pt_regs. | |
673 | ||
b9ab5ebb JP |
674 | config HAVE_STACK_VALIDATION |
675 | bool | |
676 | help | |
677 | Architecture supports the 'objtool check' host tool command, which | |
678 | performs compile-time stack metadata validation. | |
679 | ||
468a9428 GS |
680 | config HAVE_ARCH_HASH |
681 | bool | |
682 | default n | |
683 | help | |
684 | If this is set, the architecture provides an <asm/hash.h> | |
685 | file which provides platform-specific implementations of some | |
686 | functions in <linux/hash.h> or fs/namei.c. | |
687 | ||
3a495511 WBG |
688 | config ISA_BUS_API |
689 | def_bool ISA | |
690 | ||
d2125043 AV |
691 | # |
692 | # ABI hall of shame | |
693 | # | |
694 | config CLONE_BACKWARDS | |
695 | bool | |
696 | help | |
697 | Architecture has tls passed as the 4th argument of clone(2), | |
698 | not the 5th one. | |
699 | ||
700 | config CLONE_BACKWARDS2 | |
701 | bool | |
702 | help | |
703 | Architecture has the first two arguments of clone(2) swapped. | |
704 | ||
dfa9771a MS |
705 | config CLONE_BACKWARDS3 |
706 | bool | |
707 | help | |
708 | Architecture has tls passed as the 3rd argument of clone(2), | |
709 | not the 5th one. | |
710 | ||
eaca6eae AV |
711 | config ODD_RT_SIGACTION |
712 | bool | |
713 | help | |
714 | Architecture has unusual rt_sigaction(2) arguments | |
715 | ||
0a0e8cdf AV |
716 | config OLD_SIGSUSPEND |
717 | bool | |
718 | help | |
719 | Architecture has old sigsuspend(2) syscall, of one-argument variety | |
720 | ||
721 | config OLD_SIGSUSPEND3 | |
722 | bool | |
723 | help | |
724 | Even weirder antique ABI - three-argument sigsuspend(2) | |
725 | ||
495dfbf7 AV |
726 | config OLD_SIGACTION |
727 | bool | |
728 | help | |
729 | Architecture has old sigaction(2) syscall. Nope, not the same | |
730 | as OLD_SIGSUSPEND | OLD_SIGSUSPEND3 - alpha has sigsuspend(2), | |
731 | but fairly different variant of sigaction(2), thanks to OSF/1 | |
732 | compatibility... | |
733 | ||
734 | config COMPAT_OLD_SIGACTION | |
735 | bool | |
736 | ||
0d4a619b CH |
737 | config ARCH_NO_COHERENT_DMA_MMAP |
738 | bool | |
739 | ||
fff7fb0b ZZ |
740 | config CPU_NO_EFFICIENT_FFS |
741 | def_bool n | |
742 | ||
ba14a194 AL |
743 | config HAVE_ARCH_VMAP_STACK |
744 | def_bool n | |
745 | help | |
746 | An arch should select this symbol if it can support kernel stacks | |
747 | in vmalloc space. This means: | |
748 | ||
749 | - vmalloc space must be large enough to hold many kernel stacks. | |
750 | This may rule out many 32-bit architectures. | |
751 | ||
752 | - Stacks in vmalloc space need to work reliably. For example, if | |
753 | vmap page tables are created on demand, either this mechanism | |
754 | needs to work while the stack points to a virtual address with | |
755 | unpopulated page tables or arch code (switch_to() and switch_mm(), | |
756 | most likely) needs to ensure that the stack's page table entries | |
757 | are populated before running on a possibly unpopulated stack. | |
758 | ||
759 | - If the stack overflows into a guard page, something reasonable | |
760 | should happen. The definition of "reasonable" is flexible, but | |
761 | instantly rebooting without logging anything would be unfriendly. | |
762 | ||
763 | config VMAP_STACK | |
764 | default y | |
765 | bool "Use a virtually-mapped stack" | |
766 | depends on HAVE_ARCH_VMAP_STACK && !KASAN | |
767 | ---help--- | |
768 | Enable this if you want the use virtually-mapped kernel stacks | |
769 | with guard pages. This causes kernel stack overflows to be | |
770 | caught immediately rather than causing difficult-to-diagnose | |
771 | corruption. | |
772 | ||
773 | This is presently incompatible with KASAN because KASAN expects | |
774 | the stack to map directly to the KASAN shadow map using a formula | |
775 | that is incorrect if the stack is in vmalloc space. | |
776 | ||
2521f2c2 | 777 | source "kernel/gcov/Kconfig" |