Commit | Line | Data |
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b2441318 | 1 | # SPDX-License-Identifier: GPL-2.0 |
fb32e03f MD |
2 | # |
3 | # General architecture dependent options | |
4 | # | |
125e5645 | 5 | |
1572497c CH |
6 | # |
7 | # Note: arch/$(SRCARCH)/Kconfig needs to be included first so that it can | |
8 | # override the default values in this file. | |
9 | # | |
10 | source "arch/$(SRCARCH)/Kconfig" | |
11 | ||
22471e13 RD |
12 | menu "General architecture-dependent options" |
13 | ||
692f66f2 HB |
14 | config CRASH_CORE |
15 | bool | |
16 | ||
2965faa5 | 17 | config KEXEC_CORE |
692f66f2 | 18 | select CRASH_CORE |
2965faa5 DY |
19 | bool |
20 | ||
467d2782 TJB |
21 | config HAVE_IMA_KEXEC |
22 | bool | |
23 | ||
05736e4a TG |
24 | config HOTPLUG_SMT |
25 | bool | |
26 | ||
125e5645 | 27 | config OPROFILE |
b309a294 | 28 | tristate "OProfile system profiling" |
125e5645 MD |
29 | depends on PROFILING |
30 | depends on HAVE_OPROFILE | |
d69d59f4 | 31 | select RING_BUFFER |
9a5963eb | 32 | select RING_BUFFER_ALLOW_SWAP |
125e5645 MD |
33 | help |
34 | OProfile is a profiling system capable of profiling the | |
35 | whole system, include the kernel, kernel modules, libraries, | |
36 | and applications. | |
37 | ||
38 | If unsure, say N. | |
39 | ||
4d4036e0 JY |
40 | config OPROFILE_EVENT_MULTIPLEX |
41 | bool "OProfile multiplexing support (EXPERIMENTAL)" | |
42 | default n | |
43 | depends on OPROFILE && X86 | |
44 | help | |
45 | The number of hardware counters is limited. The multiplexing | |
46 | feature enables OProfile to gather more events than counters | |
47 | are provided by the hardware. This is realized by switching | |
9332ef9d | 48 | between events at a user specified time interval. |
4d4036e0 JY |
49 | |
50 | If unsure, say N. | |
51 | ||
125e5645 | 52 | config HAVE_OPROFILE |
9ba16087 | 53 | bool |
125e5645 | 54 | |
dcfce4a0 RR |
55 | config OPROFILE_NMI_TIMER |
56 | def_bool y | |
af9feebe | 57 | depends on PERF_EVENTS && HAVE_PERF_EVENTS_NMI && !PPC64 |
dcfce4a0 | 58 | |
125e5645 MD |
59 | config KPROBES |
60 | bool "Kprobes" | |
05ed160e | 61 | depends on MODULES |
125e5645 | 62 | depends on HAVE_KPROBES |
05ed160e | 63 | select KALLSYMS |
125e5645 MD |
64 | help |
65 | Kprobes allows you to trap at almost any kernel address and | |
66 | execute a callback function. register_kprobe() establishes | |
67 | a probepoint and specifies the callback. Kprobes is useful | |
68 | for kernel debugging, non-intrusive instrumentation and testing. | |
69 | If in doubt, say "N". | |
70 | ||
45f81b1c | 71 | config JUMP_LABEL |
c5905afb | 72 | bool "Optimize very unlikely/likely branches" |
45f81b1c | 73 | depends on HAVE_ARCH_JUMP_LABEL |
e9666d10 | 74 | depends on CC_HAS_ASM_GOTO |
45f81b1c | 75 | help |
c5905afb IM |
76 | This option enables a transparent branch optimization that |
77 | makes certain almost-always-true or almost-always-false branch | |
78 | conditions even cheaper to execute within the kernel. | |
79 | ||
80 | Certain performance-sensitive kernel code, such as trace points, | |
81 | scheduler functionality, networking code and KVM have such | |
82 | branches and include support for this optimization technique. | |
83 | ||
45f81b1c | 84 | If it is detected that the compiler has support for "asm goto", |
c5905afb IM |
85 | the kernel will compile such branches with just a nop |
86 | instruction. When the condition flag is toggled to true, the | |
87 | nop will be converted to a jump instruction to execute the | |
88 | conditional block of instructions. | |
89 | ||
90 | This technique lowers overhead and stress on the branch prediction | |
91 | of the processor and generally makes the kernel faster. The update | |
92 | of the condition is slower, but those are always very rare. | |
45f81b1c | 93 | |
c5905afb IM |
94 | ( On 32-bit x86, the necessary options added to the compiler |
95 | flags may increase the size of the kernel slightly. ) | |
45f81b1c | 96 | |
1987c947 PZ |
97 | config STATIC_KEYS_SELFTEST |
98 | bool "Static key selftest" | |
99 | depends on JUMP_LABEL | |
100 | help | |
101 | Boot time self-test of the branch patching code. | |
102 | ||
afd66255 | 103 | config OPTPROBES |
5cc718b9 MH |
104 | def_bool y |
105 | depends on KPROBES && HAVE_OPTPROBES | |
a30b85df | 106 | select TASKS_RCU if PREEMPT |
afd66255 | 107 | |
e7dbfe34 MH |
108 | config KPROBES_ON_FTRACE |
109 | def_bool y | |
110 | depends on KPROBES && HAVE_KPROBES_ON_FTRACE | |
111 | depends on DYNAMIC_FTRACE_WITH_REGS | |
112 | help | |
113 | If function tracer is enabled and the arch supports full | |
114 | passing of pt_regs to function tracing, then kprobes can | |
115 | optimize on top of function tracing. | |
116 | ||
2b144498 | 117 | config UPROBES |
09294e31 | 118 | def_bool n |
e8f4aa60 | 119 | depends on ARCH_SUPPORTS_UPROBES |
2b144498 | 120 | help |
7b2d81d4 IM |
121 | Uprobes is the user-space counterpart to kprobes: they |
122 | enable instrumentation applications (such as 'perf probe') | |
123 | to establish unintrusive probes in user-space binaries and | |
124 | libraries, by executing handler functions when the probes | |
125 | are hit by user-space applications. | |
126 | ||
127 | ( These probes come in the form of single-byte breakpoints, | |
128 | managed by the kernel and kept transparent to the probed | |
129 | application. ) | |
2b144498 | 130 | |
58340a07 | 131 | config HAVE_EFFICIENT_UNALIGNED_ACCESS |
9ba16087 | 132 | bool |
58340a07 JB |
133 | help |
134 | Some architectures are unable to perform unaligned accesses | |
135 | without the use of get_unaligned/put_unaligned. Others are | |
136 | unable to perform such accesses efficiently (e.g. trap on | |
137 | unaligned access and require fixing it up in the exception | |
138 | handler.) | |
139 | ||
140 | This symbol should be selected by an architecture if it can | |
141 | perform unaligned accesses efficiently to allow different | |
142 | code paths to be selected for these cases. Some network | |
143 | drivers, for example, could opt to not fix up alignment | |
144 | problems with received packets if doing so would not help | |
145 | much. | |
146 | ||
147 | See Documentation/unaligned-memory-access.txt for more | |
148 | information on the topic of unaligned memory accesses. | |
149 | ||
cf66bb93 DW |
150 | config ARCH_USE_BUILTIN_BSWAP |
151 | bool | |
152 | help | |
153 | Modern versions of GCC (since 4.4) have builtin functions | |
154 | for handling byte-swapping. Using these, instead of the old | |
155 | inline assembler that the architecture code provides in the | |
156 | __arch_bswapXX() macros, allows the compiler to see what's | |
157 | happening and offers more opportunity for optimisation. In | |
158 | particular, the compiler will be able to combine the byteswap | |
159 | with a nearby load or store and use load-and-swap or | |
160 | store-and-swap instructions if the architecture has them. It | |
161 | should almost *never* result in code which is worse than the | |
162 | hand-coded assembler in <asm/swab.h>. But just in case it | |
163 | does, the use of the builtins is optional. | |
164 | ||
165 | Any architecture with load-and-swap or store-and-swap | |
166 | instructions should set this. And it shouldn't hurt to set it | |
167 | on architectures that don't have such instructions. | |
168 | ||
9edddaa2 AM |
169 | config KRETPROBES |
170 | def_bool y | |
171 | depends on KPROBES && HAVE_KRETPROBES | |
172 | ||
7c68af6e AK |
173 | config USER_RETURN_NOTIFIER |
174 | bool | |
175 | depends on HAVE_USER_RETURN_NOTIFIER | |
176 | help | |
177 | Provide a kernel-internal notification when a cpu is about to | |
178 | switch to user mode. | |
179 | ||
28b2ee20 | 180 | config HAVE_IOREMAP_PROT |
9ba16087 | 181 | bool |
28b2ee20 | 182 | |
125e5645 | 183 | config HAVE_KPROBES |
9ba16087 | 184 | bool |
9edddaa2 AM |
185 | |
186 | config HAVE_KRETPROBES | |
9ba16087 | 187 | bool |
74bc7cee | 188 | |
afd66255 MH |
189 | config HAVE_OPTPROBES |
190 | bool | |
d314d74c | 191 | |
e7dbfe34 MH |
192 | config HAVE_KPROBES_ON_FTRACE |
193 | bool | |
194 | ||
540adea3 | 195 | config HAVE_FUNCTION_ERROR_INJECTION |
9802d865 JB |
196 | bool |
197 | ||
42a0bb3f PM |
198 | config HAVE_NMI |
199 | bool | |
200 | ||
1f5a4ad9 RM |
201 | # |
202 | # An arch should select this if it provides all these things: | |
203 | # | |
204 | # task_pt_regs() in asm/processor.h or asm/ptrace.h | |
205 | # arch_has_single_step() if there is hardware single-step support | |
206 | # arch_has_block_step() if there is hardware block-step support | |
1f5a4ad9 RM |
207 | # asm/syscall.h supplying asm-generic/syscall.h interface |
208 | # linux/regset.h user_regset interfaces | |
209 | # CORE_DUMP_USE_REGSET #define'd in linux/elf.h | |
210 | # TIF_SYSCALL_TRACE calls tracehook_report_syscall_{entry,exit} | |
211 | # TIF_NOTIFY_RESUME calls tracehook_notify_resume() | |
212 | # signal delivery calls tracehook_signal_handler() | |
213 | # | |
214 | config HAVE_ARCH_TRACEHOOK | |
9ba16087 | 215 | bool |
1f5a4ad9 | 216 | |
c64be2bb MS |
217 | config HAVE_DMA_CONTIGUOUS |
218 | bool | |
219 | ||
29d5e047 TG |
220 | config GENERIC_SMP_IDLE_THREAD |
221 | bool | |
222 | ||
485cf5da KH |
223 | config GENERIC_IDLE_POLL_SETUP |
224 | bool | |
225 | ||
6974f0c4 DM |
226 | config ARCH_HAS_FORTIFY_SOURCE |
227 | bool | |
228 | help | |
229 | An architecture should select this when it can successfully | |
230 | build and run with CONFIG_FORTIFY_SOURCE. | |
231 | ||
d8ae8a37 CH |
232 | # |
233 | # Select if the arch provides a historic keepinit alias for the retain_initrd | |
234 | # command line option | |
235 | # | |
236 | config ARCH_HAS_KEEPINITRD | |
237 | bool | |
238 | ||
d2852a22 DB |
239 | # Select if arch has all set_memory_ro/rw/x/nx() functions in asm/cacheflush.h |
240 | config ARCH_HAS_SET_MEMORY | |
241 | bool | |
242 | ||
d253ca0c RE |
243 | # Select if arch has all set_direct_map_invalid/default() functions |
244 | config ARCH_HAS_SET_DIRECT_MAP | |
245 | bool | |
246 | ||
c30700db CH |
247 | # |
248 | # Select if arch has an uncached kernel segment and provides the | |
249 | # uncached_kernel_address / cached_kernel_address symbols to use it | |
250 | # | |
251 | config ARCH_HAS_UNCACHED_SEGMENT | |
252 | select ARCH_HAS_DMA_PREP_COHERENT | |
253 | bool | |
254 | ||
0500871f DH |
255 | # Select if arch init_task must go in the __init_task_data section |
256 | config ARCH_TASK_STRUCT_ON_STACK | |
a4a2eb49 TG |
257 | bool |
258 | ||
f5e10287 TG |
259 | # Select if arch has its private alloc_task_struct() function |
260 | config ARCH_TASK_STRUCT_ALLOCATOR | |
261 | bool | |
262 | ||
5905429a KC |
263 | config HAVE_ARCH_THREAD_STRUCT_WHITELIST |
264 | bool | |
265 | depends on !ARCH_TASK_STRUCT_ALLOCATOR | |
266 | help | |
267 | An architecture should select this to provide hardened usercopy | |
268 | knowledge about what region of the thread_struct should be | |
269 | whitelisted for copying to userspace. Normally this is only the | |
270 | FPU registers. Specifically, arch_thread_struct_whitelist() | |
271 | should be implemented. Without this, the entire thread_struct | |
272 | field in task_struct will be left whitelisted. | |
273 | ||
b235beea LT |
274 | # Select if arch has its private alloc_thread_stack() function |
275 | config ARCH_THREAD_STACK_ALLOCATOR | |
f5e10287 TG |
276 | bool |
277 | ||
5aaeb5c0 IM |
278 | # Select if arch wants to size task_struct dynamically via arch_task_struct_size: |
279 | config ARCH_WANTS_DYNAMIC_TASK_STRUCT | |
280 | bool | |
281 | ||
942fa985 YN |
282 | config ARCH_32BIT_OFF_T |
283 | bool | |
284 | depends on !64BIT | |
285 | help | |
286 | All new 32-bit architectures should have 64-bit off_t type on | |
287 | userspace side which corresponds to the loff_t kernel type. This | |
288 | is the requirement for modern ABIs. Some existing architectures | |
289 | still support 32-bit off_t. This option is enabled for all such | |
290 | architectures explicitly. | |
291 | ||
f850c30c HC |
292 | config HAVE_REGS_AND_STACK_ACCESS_API |
293 | bool | |
e01292b1 HC |
294 | help |
295 | This symbol should be selected by an architecure if it supports | |
296 | the API needed to access registers and stack entries from pt_regs, | |
297 | declared in asm/ptrace.h | |
298 | For example the kprobes-based event tracer needs this API. | |
f850c30c | 299 | |
d7822b1e MD |
300 | config HAVE_RSEQ |
301 | bool | |
302 | depends on HAVE_REGS_AND_STACK_ACCESS_API | |
303 | help | |
304 | This symbol should be selected by an architecture if it | |
305 | supports an implementation of restartable sequences. | |
306 | ||
3c88ee19 MH |
307 | config HAVE_FUNCTION_ARG_ACCESS_API |
308 | bool | |
309 | help | |
310 | This symbol should be selected by an architecure if it supports | |
311 | the API needed to access function arguments from pt_regs, | |
312 | declared in asm/ptrace.h | |
313 | ||
9483a578 | 314 | config HAVE_CLK |
9ba16087 | 315 | bool |
9483a578 DB |
316 | help |
317 | The <linux/clk.h> calls support software clock gating and | |
318 | thus are a key power management tool on many systems. | |
319 | ||
62a038d3 P |
320 | config HAVE_HW_BREAKPOINT |
321 | bool | |
99e8c5a3 | 322 | depends on PERF_EVENTS |
62a038d3 | 323 | |
0102752e FW |
324 | config HAVE_MIXED_BREAKPOINTS_REGS |
325 | bool | |
326 | depends on HAVE_HW_BREAKPOINT | |
327 | help | |
328 | Depending on the arch implementation of hardware breakpoints, | |
329 | some of them have separate registers for data and instruction | |
330 | breakpoints addresses, others have mixed registers to store | |
331 | them but define the access type in a control register. | |
332 | Select this option if your arch implements breakpoints under the | |
333 | latter fashion. | |
334 | ||
7c68af6e AK |
335 | config HAVE_USER_RETURN_NOTIFIER |
336 | bool | |
a1922ed6 | 337 | |
c01d4323 FW |
338 | config HAVE_PERF_EVENTS_NMI |
339 | bool | |
23637d47 FW |
340 | help |
341 | System hardware can generate an NMI using the perf event | |
342 | subsystem. Also has support for calculating CPU cycle events | |
343 | to determine how many clock cycles in a given period. | |
c01d4323 | 344 | |
05a4a952 NP |
345 | config HAVE_HARDLOCKUP_DETECTOR_PERF |
346 | bool | |
347 | depends on HAVE_PERF_EVENTS_NMI | |
348 | help | |
349 | The arch chooses to use the generic perf-NMI-based hardlockup | |
350 | detector. Must define HAVE_PERF_EVENTS_NMI. | |
351 | ||
352 | config HAVE_NMI_WATCHDOG | |
353 | depends on HAVE_NMI | |
354 | bool | |
355 | help | |
356 | The arch provides a low level NMI watchdog. It provides | |
357 | asm/nmi.h, and defines its own arch_touch_nmi_watchdog(). | |
358 | ||
359 | config HAVE_HARDLOCKUP_DETECTOR_ARCH | |
360 | bool | |
361 | select HAVE_NMI_WATCHDOG | |
362 | help | |
363 | The arch chooses to provide its own hardlockup detector, which is | |
364 | a superset of the HAVE_NMI_WATCHDOG. It also conforms to config | |
365 | interfaces and parameters provided by hardlockup detector subsystem. | |
366 | ||
c5e63197 JO |
367 | config HAVE_PERF_REGS |
368 | bool | |
369 | help | |
370 | Support selective register dumps for perf events. This includes | |
371 | bit-mapping of each registers and a unique architecture id. | |
372 | ||
c5ebcedb JO |
373 | config HAVE_PERF_USER_STACK_DUMP |
374 | bool | |
375 | help | |
376 | Support user stack dumps for perf event samples. This needs | |
377 | access to the user stack pointer which is not unified across | |
378 | architectures. | |
379 | ||
bf5438fc JB |
380 | config HAVE_ARCH_JUMP_LABEL |
381 | bool | |
382 | ||
50ff18ab AB |
383 | config HAVE_ARCH_JUMP_LABEL_RELATIVE |
384 | bool | |
385 | ||
26723911 PZ |
386 | config HAVE_RCU_TABLE_FREE |
387 | bool | |
388 | ||
96bc9567 | 389 | config HAVE_RCU_TABLE_NO_INVALIDATE |
d86564a2 PZ |
390 | bool |
391 | ||
ed6a7935 PZ |
392 | config HAVE_MMU_GATHER_PAGE_SIZE |
393 | bool | |
394 | ||
952a31c9 MS |
395 | config HAVE_MMU_GATHER_NO_GATHER |
396 | bool | |
397 | ||
df013ffb HY |
398 | config ARCH_HAVE_NMI_SAFE_CMPXCHG |
399 | bool | |
400 | ||
43570fd2 HC |
401 | config HAVE_ALIGNED_STRUCT_PAGE |
402 | bool | |
403 | help | |
404 | This makes sure that struct pages are double word aligned and that | |
405 | e.g. the SLUB allocator can perform double word atomic operations | |
406 | on a struct page for better performance. However selecting this | |
407 | might increase the size of a struct page by a word. | |
408 | ||
4156153c HC |
409 | config HAVE_CMPXCHG_LOCAL |
410 | bool | |
411 | ||
2565409f HC |
412 | config HAVE_CMPXCHG_DOUBLE |
413 | bool | |
414 | ||
77e58496 PM |
415 | config ARCH_WEAK_RELEASE_ACQUIRE |
416 | bool | |
417 | ||
c1d7e01d WD |
418 | config ARCH_WANT_IPC_PARSE_VERSION |
419 | bool | |
420 | ||
421 | config ARCH_WANT_COMPAT_IPC_PARSE_VERSION | |
422 | bool | |
423 | ||
48b25c43 | 424 | config ARCH_WANT_OLD_COMPAT_IPC |
c1d7e01d | 425 | select ARCH_WANT_COMPAT_IPC_PARSE_VERSION |
48b25c43 CM |
426 | bool |
427 | ||
e2cfabdf WD |
428 | config HAVE_ARCH_SECCOMP_FILTER |
429 | bool | |
430 | help | |
fb0fadf9 | 431 | An arch should select this symbol if it provides all of these things: |
bb6ea430 WD |
432 | - syscall_get_arch() |
433 | - syscall_get_arguments() | |
434 | - syscall_rollback() | |
435 | - syscall_set_return_value() | |
fb0fadf9 WD |
436 | - SIGSYS siginfo_t support |
437 | - secure_computing is called from a ptrace_event()-safe context | |
438 | - secure_computing return value is checked and a return value of -1 | |
439 | results in the system call being skipped immediately. | |
48dc92b9 | 440 | - seccomp syscall wired up |
e2cfabdf WD |
441 | |
442 | config SECCOMP_FILTER | |
443 | def_bool y | |
444 | depends on HAVE_ARCH_SECCOMP_FILTER && SECCOMP && NET | |
445 | help | |
446 | Enable tasks to build secure computing environments defined | |
447 | in terms of Berkeley Packet Filter programs which implement | |
448 | task-defined system call filtering polices. | |
449 | ||
5fb94e9c | 450 | See Documentation/userspace-api/seccomp_filter.rst for details. |
e2cfabdf | 451 | |
afaef01c AP |
452 | config HAVE_ARCH_STACKLEAK |
453 | bool | |
454 | help | |
455 | An architecture should select this if it has the code which | |
456 | fills the used part of the kernel stack with the STACKLEAK_POISON | |
457 | value before returning from system calls. | |
458 | ||
d148eac0 | 459 | config HAVE_STACKPROTECTOR |
19952a92 KC |
460 | bool |
461 | help | |
462 | An arch should select this symbol if: | |
19952a92 KC |
463 | - it has implemented a stack canary (e.g. __stack_chk_guard) |
464 | ||
2a61f474 MY |
465 | config CC_HAS_STACKPROTECTOR_NONE |
466 | def_bool $(cc-option,-fno-stack-protector) | |
467 | ||
050e9baa | 468 | config STACKPROTECTOR |
2a61f474 | 469 | bool "Stack Protector buffer overflow detection" |
d148eac0 | 470 | depends on HAVE_STACKPROTECTOR |
2a61f474 MY |
471 | depends on $(cc-option,-fstack-protector) |
472 | default y | |
19952a92 | 473 | help |
8779657d | 474 | This option turns on the "stack-protector" GCC feature. This |
19952a92 KC |
475 | feature puts, at the beginning of functions, a canary value on |
476 | the stack just before the return address, and validates | |
477 | the value just before actually returning. Stack based buffer | |
478 | overflows (that need to overwrite this return address) now also | |
479 | overwrite the canary, which gets detected and the attack is then | |
480 | neutralized via a kernel panic. | |
481 | ||
8779657d KC |
482 | Functions will have the stack-protector canary logic added if they |
483 | have an 8-byte or larger character array on the stack. | |
484 | ||
19952a92 | 485 | This feature requires gcc version 4.2 or above, or a distribution |
8779657d KC |
486 | gcc with the feature backported ("-fstack-protector"). |
487 | ||
488 | On an x86 "defconfig" build, this feature adds canary checks to | |
489 | about 3% of all kernel functions, which increases kernel code size | |
490 | by about 0.3%. | |
491 | ||
050e9baa | 492 | config STACKPROTECTOR_STRONG |
2a61f474 | 493 | bool "Strong Stack Protector" |
050e9baa | 494 | depends on STACKPROTECTOR |
2a61f474 MY |
495 | depends on $(cc-option,-fstack-protector-strong) |
496 | default y | |
8779657d KC |
497 | help |
498 | Functions will have the stack-protector canary logic added in any | |
499 | of the following conditions: | |
500 | ||
501 | - local variable's address used as part of the right hand side of an | |
502 | assignment or function argument | |
503 | - local variable is an array (or union containing an array), | |
504 | regardless of array type or length | |
505 | - uses register local variables | |
506 | ||
507 | This feature requires gcc version 4.9 or above, or a distribution | |
508 | gcc with the feature backported ("-fstack-protector-strong"). | |
509 | ||
510 | On an x86 "defconfig" build, this feature adds canary checks to | |
511 | about 20% of all kernel functions, which increases the kernel code | |
512 | size by about 2%. | |
513 | ||
0f60a8ef KC |
514 | config HAVE_ARCH_WITHIN_STACK_FRAMES |
515 | bool | |
516 | help | |
517 | An architecture should select this if it can walk the kernel stack | |
518 | frames to determine if an object is part of either the arguments | |
519 | or local variables (i.e. that it excludes saved return addresses, | |
520 | and similar) by implementing an inline arch_within_stack_frames(), | |
521 | which is used by CONFIG_HARDENED_USERCOPY. | |
522 | ||
91d1aa43 | 523 | config HAVE_CONTEXT_TRACKING |
2b1d5024 FW |
524 | bool |
525 | help | |
91d1aa43 FW |
526 | Provide kernel/user boundaries probes necessary for subsystems |
527 | that need it, such as userspace RCU extended quiescent state. | |
528 | Syscalls need to be wrapped inside user_exit()-user_enter() through | |
529 | the slow path using TIF_NOHZ flag. Exceptions handlers must be | |
530 | wrapped as well. Irqs are already protected inside | |
531 | rcu_irq_enter/rcu_irq_exit() but preemption or signal handling on | |
532 | irq exit still need to be protected. | |
2b1d5024 | 533 | |
b952741c FW |
534 | config HAVE_VIRT_CPU_ACCOUNTING |
535 | bool | |
536 | ||
40565b5a SG |
537 | config ARCH_HAS_SCALED_CPUTIME |
538 | bool | |
539 | ||
554b0004 KH |
540 | config HAVE_VIRT_CPU_ACCOUNTING_GEN |
541 | bool | |
542 | default y if 64BIT | |
543 | help | |
544 | With VIRT_CPU_ACCOUNTING_GEN, cputime_t becomes 64-bit. | |
545 | Before enabling this option, arch code must be audited | |
546 | to ensure there are no races in concurrent read/write of | |
547 | cputime_t. For example, reading/writing 64-bit cputime_t on | |
548 | some 32-bit arches may require multiple accesses, so proper | |
549 | locking is needed to protect against concurrent accesses. | |
550 | ||
551 | ||
fdf9c356 FW |
552 | config HAVE_IRQ_TIME_ACCOUNTING |
553 | bool | |
554 | help | |
555 | Archs need to ensure they use a high enough resolution clock to | |
556 | support irq time accounting and then call enable_sched_clock_irqtime(). | |
557 | ||
2c91bd4a JFG |
558 | config HAVE_MOVE_PMD |
559 | bool | |
560 | help | |
561 | Archs that select this are able to move page tables at the PMD level. | |
562 | ||
15626062 GS |
563 | config HAVE_ARCH_TRANSPARENT_HUGEPAGE |
564 | bool | |
565 | ||
a00cc7d9 MW |
566 | config HAVE_ARCH_TRANSPARENT_HUGEPAGE_PUD |
567 | bool | |
568 | ||
0ddab1d2 TK |
569 | config HAVE_ARCH_HUGE_VMAP |
570 | bool | |
571 | ||
3876d4a3 AG |
572 | config ARCH_WANT_HUGE_PMD_SHARE |
573 | bool | |
574 | ||
0f8975ec PE |
575 | config HAVE_ARCH_SOFT_DIRTY |
576 | bool | |
577 | ||
786d35d4 DH |
578 | config HAVE_MOD_ARCH_SPECIFIC |
579 | bool | |
580 | help | |
581 | The arch uses struct mod_arch_specific to store data. Many arches | |
582 | just need a simple module loader without arch specific data - those | |
583 | should not enable this. | |
584 | ||
585 | config MODULES_USE_ELF_RELA | |
586 | bool | |
587 | help | |
588 | Modules only use ELF RELA relocations. Modules with ELF REL | |
589 | relocations will give an error. | |
590 | ||
591 | config MODULES_USE_ELF_REL | |
592 | bool | |
593 | help | |
594 | Modules only use ELF REL relocations. Modules with ELF RELA | |
595 | relocations will give an error. | |
596 | ||
cc1f0274 FW |
597 | config HAVE_IRQ_EXIT_ON_IRQ_STACK |
598 | bool | |
599 | help | |
600 | Architecture doesn't only execute the irq handler on the irq stack | |
601 | but also irq_exit(). This way we can process softirqs on this irq | |
602 | stack instead of switching to a new one when we call __do_softirq() | |
603 | in the end of an hardirq. | |
604 | This spares a stack switch and improves cache usage on softirq | |
605 | processing. | |
606 | ||
235a8f02 KS |
607 | config PGTABLE_LEVELS |
608 | int | |
609 | default 2 | |
610 | ||
2b68f6ca KC |
611 | config ARCH_HAS_ELF_RANDOMIZE |
612 | bool | |
613 | help | |
614 | An architecture supports choosing randomized locations for | |
615 | stack, mmap, brk, and ET_DYN. Defined functions: | |
616 | - arch_mmap_rnd() | |
204db6ed | 617 | - arch_randomize_brk() |
2b68f6ca | 618 | |
d07e2259 DC |
619 | config HAVE_ARCH_MMAP_RND_BITS |
620 | bool | |
621 | help | |
622 | An arch should select this symbol if it supports setting a variable | |
623 | number of bits for use in establishing the base address for mmap | |
624 | allocations, has MMU enabled and provides values for both: | |
625 | - ARCH_MMAP_RND_BITS_MIN | |
626 | - ARCH_MMAP_RND_BITS_MAX | |
627 | ||
5f56a5df JS |
628 | config HAVE_EXIT_THREAD |
629 | bool | |
630 | help | |
631 | An architecture implements exit_thread. | |
632 | ||
d07e2259 DC |
633 | config ARCH_MMAP_RND_BITS_MIN |
634 | int | |
635 | ||
636 | config ARCH_MMAP_RND_BITS_MAX | |
637 | int | |
638 | ||
639 | config ARCH_MMAP_RND_BITS_DEFAULT | |
640 | int | |
641 | ||
642 | config ARCH_MMAP_RND_BITS | |
643 | int "Number of bits to use for ASLR of mmap base address" if EXPERT | |
644 | range ARCH_MMAP_RND_BITS_MIN ARCH_MMAP_RND_BITS_MAX | |
645 | default ARCH_MMAP_RND_BITS_DEFAULT if ARCH_MMAP_RND_BITS_DEFAULT | |
646 | default ARCH_MMAP_RND_BITS_MIN | |
647 | depends on HAVE_ARCH_MMAP_RND_BITS | |
648 | help | |
649 | This value can be used to select the number of bits to use to | |
650 | determine the random offset to the base address of vma regions | |
651 | resulting from mmap allocations. This value will be bounded | |
652 | by the architecture's minimum and maximum supported values. | |
653 | ||
654 | This value can be changed after boot using the | |
655 | /proc/sys/vm/mmap_rnd_bits tunable | |
656 | ||
657 | config HAVE_ARCH_MMAP_RND_COMPAT_BITS | |
658 | bool | |
659 | help | |
660 | An arch should select this symbol if it supports running applications | |
661 | in compatibility mode, supports setting a variable number of bits for | |
662 | use in establishing the base address for mmap allocations, has MMU | |
663 | enabled and provides values for both: | |
664 | - ARCH_MMAP_RND_COMPAT_BITS_MIN | |
665 | - ARCH_MMAP_RND_COMPAT_BITS_MAX | |
666 | ||
667 | config ARCH_MMAP_RND_COMPAT_BITS_MIN | |
668 | int | |
669 | ||
670 | config ARCH_MMAP_RND_COMPAT_BITS_MAX | |
671 | int | |
672 | ||
673 | config ARCH_MMAP_RND_COMPAT_BITS_DEFAULT | |
674 | int | |
675 | ||
676 | config ARCH_MMAP_RND_COMPAT_BITS | |
677 | int "Number of bits to use for ASLR of mmap base address for compatible applications" if EXPERT | |
678 | range ARCH_MMAP_RND_COMPAT_BITS_MIN ARCH_MMAP_RND_COMPAT_BITS_MAX | |
679 | default ARCH_MMAP_RND_COMPAT_BITS_DEFAULT if ARCH_MMAP_RND_COMPAT_BITS_DEFAULT | |
680 | default ARCH_MMAP_RND_COMPAT_BITS_MIN | |
681 | depends on HAVE_ARCH_MMAP_RND_COMPAT_BITS | |
682 | help | |
683 | This value can be used to select the number of bits to use to | |
684 | determine the random offset to the base address of vma regions | |
685 | resulting from mmap allocations for compatible applications This | |
686 | value will be bounded by the architecture's minimum and maximum | |
687 | supported values. | |
688 | ||
689 | This value can be changed after boot using the | |
690 | /proc/sys/vm/mmap_rnd_compat_bits tunable | |
691 | ||
1b028f78 DS |
692 | config HAVE_ARCH_COMPAT_MMAP_BASES |
693 | bool | |
694 | help | |
695 | This allows 64bit applications to invoke 32-bit mmap() syscall | |
696 | and vice-versa 32-bit applications to call 64-bit mmap(). | |
697 | Required for applications doing different bitness syscalls. | |
698 | ||
3033f14a JT |
699 | config HAVE_COPY_THREAD_TLS |
700 | bool | |
701 | help | |
702 | Architecture provides copy_thread_tls to accept tls argument via | |
703 | normal C parameter passing, rather than extracting the syscall | |
704 | argument from pt_regs. | |
705 | ||
b9ab5ebb JP |
706 | config HAVE_STACK_VALIDATION |
707 | bool | |
708 | help | |
709 | Architecture supports the 'objtool check' host tool command, which | |
710 | performs compile-time stack metadata validation. | |
711 | ||
af085d90 JP |
712 | config HAVE_RELIABLE_STACKTRACE |
713 | bool | |
714 | help | |
715 | Architecture has a save_stack_trace_tsk_reliable() function which | |
716 | only returns a stack trace if it can guarantee the trace is reliable. | |
717 | ||
468a9428 GS |
718 | config HAVE_ARCH_HASH |
719 | bool | |
720 | default n | |
721 | help | |
722 | If this is set, the architecture provides an <asm/hash.h> | |
723 | file which provides platform-specific implementations of some | |
724 | functions in <linux/hash.h> or fs/namei.c. | |
725 | ||
666047fe FT |
726 | config HAVE_ARCH_NVRAM_OPS |
727 | bool | |
728 | ||
3a495511 WBG |
729 | config ISA_BUS_API |
730 | def_bool ISA | |
731 | ||
d2125043 AV |
732 | # |
733 | # ABI hall of shame | |
734 | # | |
735 | config CLONE_BACKWARDS | |
736 | bool | |
737 | help | |
738 | Architecture has tls passed as the 4th argument of clone(2), | |
739 | not the 5th one. | |
740 | ||
741 | config CLONE_BACKWARDS2 | |
742 | bool | |
743 | help | |
744 | Architecture has the first two arguments of clone(2) swapped. | |
745 | ||
dfa9771a MS |
746 | config CLONE_BACKWARDS3 |
747 | bool | |
748 | help | |
749 | Architecture has tls passed as the 3rd argument of clone(2), | |
750 | not the 5th one. | |
751 | ||
eaca6eae AV |
752 | config ODD_RT_SIGACTION |
753 | bool | |
754 | help | |
755 | Architecture has unusual rt_sigaction(2) arguments | |
756 | ||
0a0e8cdf AV |
757 | config OLD_SIGSUSPEND |
758 | bool | |
759 | help | |
760 | Architecture has old sigsuspend(2) syscall, of one-argument variety | |
761 | ||
762 | config OLD_SIGSUSPEND3 | |
763 | bool | |
764 | help | |
765 | Even weirder antique ABI - three-argument sigsuspend(2) | |
766 | ||
495dfbf7 AV |
767 | config OLD_SIGACTION |
768 | bool | |
769 | help | |
770 | Architecture has old sigaction(2) syscall. Nope, not the same | |
771 | as OLD_SIGSUSPEND | OLD_SIGSUSPEND3 - alpha has sigsuspend(2), | |
772 | but fairly different variant of sigaction(2), thanks to OSF/1 | |
773 | compatibility... | |
774 | ||
775 | config COMPAT_OLD_SIGACTION | |
776 | bool | |
777 | ||
d4703dda | 778 | config 64BIT_TIME |
f3d96467 | 779 | def_bool y |
d4703dda DD |
780 | help |
781 | This should be selected by all architectures that need to support | |
782 | new system calls with a 64-bit time_t. This is relevant on all 32-bit | |
783 | architectures, and 64-bit architectures as part of compat syscall | |
784 | handling. | |
785 | ||
17435e5f | 786 | config COMPAT_32BIT_TIME |
00bf25d6 | 787 | def_bool !64BIT || COMPAT |
17435e5f DD |
788 | help |
789 | This enables 32 bit time_t support in addition to 64 bit time_t support. | |
790 | This is relevant on all 32-bit architectures, and 64-bit architectures | |
791 | as part of compat syscall handling. | |
792 | ||
0d4a619b CH |
793 | config ARCH_NO_COHERENT_DMA_MMAP |
794 | bool | |
795 | ||
87a4c375 CH |
796 | config ARCH_NO_PREEMPT |
797 | bool | |
798 | ||
a50a3f4b TG |
799 | config ARCH_SUPPORTS_RT |
800 | bool | |
801 | ||
fff7fb0b ZZ |
802 | config CPU_NO_EFFICIENT_FFS |
803 | def_bool n | |
804 | ||
ba14a194 AL |
805 | config HAVE_ARCH_VMAP_STACK |
806 | def_bool n | |
807 | help | |
808 | An arch should select this symbol if it can support kernel stacks | |
809 | in vmalloc space. This means: | |
810 | ||
811 | - vmalloc space must be large enough to hold many kernel stacks. | |
812 | This may rule out many 32-bit architectures. | |
813 | ||
814 | - Stacks in vmalloc space need to work reliably. For example, if | |
815 | vmap page tables are created on demand, either this mechanism | |
816 | needs to work while the stack points to a virtual address with | |
817 | unpopulated page tables or arch code (switch_to() and switch_mm(), | |
818 | most likely) needs to ensure that the stack's page table entries | |
819 | are populated before running on a possibly unpopulated stack. | |
820 | ||
821 | - If the stack overflows into a guard page, something reasonable | |
822 | should happen. The definition of "reasonable" is flexible, but | |
823 | instantly rebooting without logging anything would be unfriendly. | |
824 | ||
825 | config VMAP_STACK | |
826 | default y | |
827 | bool "Use a virtually-mapped stack" | |
828 | depends on HAVE_ARCH_VMAP_STACK && !KASAN | |
829 | ---help--- | |
830 | Enable this if you want the use virtually-mapped kernel stacks | |
831 | with guard pages. This causes kernel stack overflows to be | |
832 | caught immediately rather than causing difficult-to-diagnose | |
833 | corruption. | |
834 | ||
835 | This is presently incompatible with KASAN because KASAN expects | |
836 | the stack to map directly to the KASAN shadow map using a formula | |
837 | that is incorrect if the stack is in vmalloc space. | |
838 | ||
ad21fc4f LA |
839 | config ARCH_OPTIONAL_KERNEL_RWX |
840 | def_bool n | |
841 | ||
842 | config ARCH_OPTIONAL_KERNEL_RWX_DEFAULT | |
843 | def_bool n | |
844 | ||
845 | config ARCH_HAS_STRICT_KERNEL_RWX | |
846 | def_bool n | |
847 | ||
0f5bf6d0 | 848 | config STRICT_KERNEL_RWX |
ad21fc4f LA |
849 | bool "Make kernel text and rodata read-only" if ARCH_OPTIONAL_KERNEL_RWX |
850 | depends on ARCH_HAS_STRICT_KERNEL_RWX | |
851 | default !ARCH_OPTIONAL_KERNEL_RWX || ARCH_OPTIONAL_KERNEL_RWX_DEFAULT | |
852 | help | |
853 | If this is set, kernel text and rodata memory will be made read-only, | |
854 | and non-text memory will be made non-executable. This provides | |
855 | protection against certain security exploits (e.g. executing the heap | |
856 | or modifying text) | |
857 | ||
858 | These features are considered standard security practice these days. | |
859 | You should say Y here in almost all cases. | |
860 | ||
861 | config ARCH_HAS_STRICT_MODULE_RWX | |
862 | def_bool n | |
863 | ||
0f5bf6d0 | 864 | config STRICT_MODULE_RWX |
ad21fc4f LA |
865 | bool "Set loadable kernel module data as NX and text as RO" if ARCH_OPTIONAL_KERNEL_RWX |
866 | depends on ARCH_HAS_STRICT_MODULE_RWX && MODULES | |
867 | default !ARCH_OPTIONAL_KERNEL_RWX || ARCH_OPTIONAL_KERNEL_RWX_DEFAULT | |
868 | help | |
869 | If this is set, module text and rodata memory will be made read-only, | |
870 | and non-text memory will be made non-executable. This provides | |
871 | protection against certain security exploits (e.g. writing to text) | |
872 | ||
ea8c64ac CH |
873 | # select if the architecture provides an asm/dma-direct.h header |
874 | config ARCH_HAS_PHYS_TO_DMA | |
875 | bool | |
876 | ||
7a46ec0e KC |
877 | config ARCH_HAS_REFCOUNT |
878 | bool | |
879 | help | |
880 | An architecture selects this when it has implemented refcount_t | |
881 | using open coded assembly primitives that provide an optimized | |
882 | refcount_t implementation, possibly at the expense of some full | |
883 | refcount state checks of CONFIG_REFCOUNT_FULL=y. | |
884 | ||
885 | The refcount overflow check behavior, however, must be retained. | |
886 | Catching overflows is the primary security concern for protecting | |
887 | against bugs in reference counts. | |
888 | ||
fd25d19f KC |
889 | config REFCOUNT_FULL |
890 | bool "Perform full reference count validation at the expense of speed" | |
891 | help | |
892 | Enabling this switches the refcounting infrastructure from a fast | |
893 | unchecked atomic_t implementation to a fully state checked | |
894 | implementation, which can be (slightly) slower but provides protections | |
895 | against various use-after-free conditions that can be used in | |
896 | security flaw exploits. | |
897 | ||
04f264d3 PB |
898 | config HAVE_ARCH_COMPILER_H |
899 | bool | |
900 | help | |
901 | An architecture can select this if it provides an | |
902 | asm/compiler.h header that should be included after | |
903 | linux/compiler-*.h in order to override macro definitions that those | |
904 | headers generally provide. | |
905 | ||
271ca788 AB |
906 | config HAVE_ARCH_PREL32_RELOCATIONS |
907 | bool | |
908 | help | |
909 | May be selected by an architecture if it supports place-relative | |
910 | 32-bit relocations, both in the toolchain and in the module loader, | |
911 | in which case relative references can be used in special sections | |
912 | for PCI fixup, initcalls etc which are only half the size on 64 bit | |
913 | architectures, and don't require runtime relocation on relocatable | |
914 | kernels. | |
915 | ||
ce9084ba AB |
916 | config ARCH_USE_MEMREMAP_PROT |
917 | bool | |
918 | ||
fb346fd9 WL |
919 | config LOCK_EVENT_COUNTS |
920 | bool "Locking event counts collection" | |
921 | depends on DEBUG_FS | |
fb346fd9 WL |
922 | ---help--- |
923 | Enable light-weight counting of various locking related events | |
924 | in the system with minimal performance impact. This reduces | |
925 | the chance of application behavior change because of timing | |
926 | differences. The counts are reported via debugfs. | |
927 | ||
2521f2c2 | 928 | source "kernel/gcov/Kconfig" |
45332b1b MY |
929 | |
930 | source "scripts/gcc-plugins/Kconfig" | |
fa1b5d09 | 931 | |
22471e13 | 932 | endmenu |