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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 | ||
175fca3b SS |
21 | config KEXEC_ELF |
22 | bool | |
23 | ||
467d2782 TJB |
24 | config HAVE_IMA_KEXEC |
25 | bool | |
26 | ||
05736e4a TG |
27 | config HOTPLUG_SMT |
28 | bool | |
29 | ||
125e5645 | 30 | config OPROFILE |
b309a294 | 31 | tristate "OProfile system profiling" |
125e5645 MD |
32 | depends on PROFILING |
33 | depends on HAVE_OPROFILE | |
d69d59f4 | 34 | select RING_BUFFER |
9a5963eb | 35 | select RING_BUFFER_ALLOW_SWAP |
125e5645 MD |
36 | help |
37 | OProfile is a profiling system capable of profiling the | |
38 | whole system, include the kernel, kernel modules, libraries, | |
39 | and applications. | |
40 | ||
41 | If unsure, say N. | |
42 | ||
4d4036e0 JY |
43 | config OPROFILE_EVENT_MULTIPLEX |
44 | bool "OProfile multiplexing support (EXPERIMENTAL)" | |
45 | default n | |
46 | depends on OPROFILE && X86 | |
47 | help | |
48 | The number of hardware counters is limited. The multiplexing | |
49 | feature enables OProfile to gather more events than counters | |
50 | are provided by the hardware. This is realized by switching | |
9332ef9d | 51 | between events at a user specified time interval. |
4d4036e0 JY |
52 | |
53 | If unsure, say N. | |
54 | ||
125e5645 | 55 | config HAVE_OPROFILE |
9ba16087 | 56 | bool |
125e5645 | 57 | |
dcfce4a0 RR |
58 | config OPROFILE_NMI_TIMER |
59 | def_bool y | |
af9feebe | 60 | depends on PERF_EVENTS && HAVE_PERF_EVENTS_NMI && !PPC64 |
dcfce4a0 | 61 | |
125e5645 MD |
62 | config KPROBES |
63 | bool "Kprobes" | |
05ed160e | 64 | depends on MODULES |
125e5645 | 65 | depends on HAVE_KPROBES |
05ed160e | 66 | select KALLSYMS |
125e5645 MD |
67 | help |
68 | Kprobes allows you to trap at almost any kernel address and | |
69 | execute a callback function. register_kprobe() establishes | |
70 | a probepoint and specifies the callback. Kprobes is useful | |
71 | for kernel debugging, non-intrusive instrumentation and testing. | |
72 | If in doubt, say "N". | |
73 | ||
45f81b1c | 74 | config JUMP_LABEL |
24b54fee KK |
75 | bool "Optimize very unlikely/likely branches" |
76 | depends on HAVE_ARCH_JUMP_LABEL | |
77 | depends on CC_HAS_ASM_GOTO | |
78 | help | |
79 | This option enables a transparent branch optimization that | |
c5905afb IM |
80 | makes certain almost-always-true or almost-always-false branch |
81 | conditions even cheaper to execute within the kernel. | |
82 | ||
83 | Certain performance-sensitive kernel code, such as trace points, | |
84 | scheduler functionality, networking code and KVM have such | |
85 | branches and include support for this optimization technique. | |
86 | ||
24b54fee | 87 | If it is detected that the compiler has support for "asm goto", |
c5905afb IM |
88 | the kernel will compile such branches with just a nop |
89 | instruction. When the condition flag is toggled to true, the | |
90 | nop will be converted to a jump instruction to execute the | |
91 | conditional block of instructions. | |
92 | ||
93 | This technique lowers overhead and stress on the branch prediction | |
94 | of the processor and generally makes the kernel faster. The update | |
95 | of the condition is slower, but those are always very rare. | |
45f81b1c | 96 | |
c5905afb IM |
97 | ( On 32-bit x86, the necessary options added to the compiler |
98 | flags may increase the size of the kernel slightly. ) | |
45f81b1c | 99 | |
1987c947 PZ |
100 | config STATIC_KEYS_SELFTEST |
101 | bool "Static key selftest" | |
102 | depends on JUMP_LABEL | |
103 | help | |
104 | Boot time self-test of the branch patching code. | |
105 | ||
afd66255 | 106 | config OPTPROBES |
5cc718b9 MH |
107 | def_bool y |
108 | depends on KPROBES && HAVE_OPTPROBES | |
01b1d88b | 109 | select TASKS_RCU if PREEMPTION |
afd66255 | 110 | |
e7dbfe34 MH |
111 | config KPROBES_ON_FTRACE |
112 | def_bool y | |
113 | depends on KPROBES && HAVE_KPROBES_ON_FTRACE | |
114 | depends on DYNAMIC_FTRACE_WITH_REGS | |
115 | help | |
116 | If function tracer is enabled and the arch supports full | |
117 | passing of pt_regs to function tracing, then kprobes can | |
118 | optimize on top of function tracing. | |
119 | ||
2b144498 | 120 | config UPROBES |
09294e31 | 121 | def_bool n |
e8f4aa60 | 122 | depends on ARCH_SUPPORTS_UPROBES |
2b144498 | 123 | help |
7b2d81d4 IM |
124 | Uprobes is the user-space counterpart to kprobes: they |
125 | enable instrumentation applications (such as 'perf probe') | |
126 | to establish unintrusive probes in user-space binaries and | |
127 | libraries, by executing handler functions when the probes | |
128 | are hit by user-space applications. | |
129 | ||
130 | ( These probes come in the form of single-byte breakpoints, | |
131 | managed by the kernel and kept transparent to the probed | |
132 | application. ) | |
2b144498 | 133 | |
58340a07 | 134 | config HAVE_EFFICIENT_UNALIGNED_ACCESS |
9ba16087 | 135 | bool |
58340a07 JB |
136 | help |
137 | Some architectures are unable to perform unaligned accesses | |
138 | without the use of get_unaligned/put_unaligned. Others are | |
139 | unable to perform such accesses efficiently (e.g. trap on | |
140 | unaligned access and require fixing it up in the exception | |
141 | handler.) | |
142 | ||
143 | This symbol should be selected by an architecture if it can | |
144 | perform unaligned accesses efficiently to allow different | |
145 | code paths to be selected for these cases. Some network | |
146 | drivers, for example, could opt to not fix up alignment | |
147 | problems with received packets if doing so would not help | |
148 | much. | |
149 | ||
150 | See Documentation/unaligned-memory-access.txt for more | |
151 | information on the topic of unaligned memory accesses. | |
152 | ||
cf66bb93 | 153 | config ARCH_USE_BUILTIN_BSWAP |
24b54fee KK |
154 | bool |
155 | help | |
cf66bb93 DW |
156 | Modern versions of GCC (since 4.4) have builtin functions |
157 | for handling byte-swapping. Using these, instead of the old | |
158 | inline assembler that the architecture code provides in the | |
159 | __arch_bswapXX() macros, allows the compiler to see what's | |
160 | happening and offers more opportunity for optimisation. In | |
161 | particular, the compiler will be able to combine the byteswap | |
162 | with a nearby load or store and use load-and-swap or | |
163 | store-and-swap instructions if the architecture has them. It | |
164 | should almost *never* result in code which is worse than the | |
165 | hand-coded assembler in <asm/swab.h>. But just in case it | |
166 | does, the use of the builtins is optional. | |
167 | ||
168 | Any architecture with load-and-swap or store-and-swap | |
169 | instructions should set this. And it shouldn't hurt to set it | |
170 | on architectures that don't have such instructions. | |
171 | ||
9edddaa2 AM |
172 | config KRETPROBES |
173 | def_bool y | |
174 | depends on KPROBES && HAVE_KRETPROBES | |
175 | ||
7c68af6e AK |
176 | config USER_RETURN_NOTIFIER |
177 | bool | |
178 | depends on HAVE_USER_RETURN_NOTIFIER | |
179 | help | |
180 | Provide a kernel-internal notification when a cpu is about to | |
181 | switch to user mode. | |
182 | ||
28b2ee20 | 183 | config HAVE_IOREMAP_PROT |
9ba16087 | 184 | bool |
28b2ee20 | 185 | |
125e5645 | 186 | config HAVE_KPROBES |
9ba16087 | 187 | bool |
9edddaa2 AM |
188 | |
189 | config HAVE_KRETPROBES | |
9ba16087 | 190 | bool |
74bc7cee | 191 | |
afd66255 MH |
192 | config HAVE_OPTPROBES |
193 | bool | |
d314d74c | 194 | |
e7dbfe34 MH |
195 | config HAVE_KPROBES_ON_FTRACE |
196 | bool | |
197 | ||
540adea3 | 198 | config HAVE_FUNCTION_ERROR_INJECTION |
9802d865 JB |
199 | bool |
200 | ||
42a0bb3f PM |
201 | config HAVE_NMI |
202 | bool | |
203 | ||
1f5a4ad9 RM |
204 | # |
205 | # An arch should select this if it provides all these things: | |
206 | # | |
207 | # task_pt_regs() in asm/processor.h or asm/ptrace.h | |
208 | # arch_has_single_step() if there is hardware single-step support | |
209 | # arch_has_block_step() if there is hardware block-step support | |
1f5a4ad9 RM |
210 | # asm/syscall.h supplying asm-generic/syscall.h interface |
211 | # linux/regset.h user_regset interfaces | |
212 | # CORE_DUMP_USE_REGSET #define'd in linux/elf.h | |
213 | # TIF_SYSCALL_TRACE calls tracehook_report_syscall_{entry,exit} | |
214 | # TIF_NOTIFY_RESUME calls tracehook_notify_resume() | |
215 | # signal delivery calls tracehook_signal_handler() | |
216 | # | |
217 | config HAVE_ARCH_TRACEHOOK | |
9ba16087 | 218 | bool |
1f5a4ad9 | 219 | |
c64be2bb MS |
220 | config HAVE_DMA_CONTIGUOUS |
221 | bool | |
222 | ||
29d5e047 | 223 | config GENERIC_SMP_IDLE_THREAD |
24b54fee | 224 | bool |
29d5e047 | 225 | |
485cf5da | 226 | config GENERIC_IDLE_POLL_SETUP |
24b54fee | 227 | bool |
485cf5da | 228 | |
6974f0c4 DM |
229 | config ARCH_HAS_FORTIFY_SOURCE |
230 | bool | |
231 | help | |
232 | An architecture should select this when it can successfully | |
233 | build and run with CONFIG_FORTIFY_SOURCE. | |
234 | ||
d8ae8a37 CH |
235 | # |
236 | # Select if the arch provides a historic keepinit alias for the retain_initrd | |
237 | # command line option | |
238 | # | |
239 | config ARCH_HAS_KEEPINITRD | |
240 | bool | |
241 | ||
d2852a22 DB |
242 | # Select if arch has all set_memory_ro/rw/x/nx() functions in asm/cacheflush.h |
243 | config ARCH_HAS_SET_MEMORY | |
244 | bool | |
245 | ||
d253ca0c RE |
246 | # Select if arch has all set_direct_map_invalid/default() functions |
247 | config ARCH_HAS_SET_DIRECT_MAP | |
248 | bool | |
249 | ||
c30700db | 250 | # |
fa7e2247 CH |
251 | # Select if the architecture provides the arch_dma_set_uncached symbol to |
252 | # either provide an uncached segement alias for a DMA allocation, or | |
253 | # to remap the page tables in place. | |
c30700db | 254 | # |
fa7e2247 | 255 | config ARCH_HAS_DMA_SET_UNCACHED |
c30700db CH |
256 | bool |
257 | ||
999a5d12 CH |
258 | # |
259 | # Select if the architectures provides the arch_dma_clear_uncached symbol | |
260 | # to undo an in-place page table remap for uncached access. | |
261 | # | |
262 | config ARCH_HAS_DMA_CLEAR_UNCACHED | |
c30700db CH |
263 | bool |
264 | ||
0500871f DH |
265 | # Select if arch init_task must go in the __init_task_data section |
266 | config ARCH_TASK_STRUCT_ON_STACK | |
24b54fee | 267 | bool |
a4a2eb49 | 268 | |
f5e10287 TG |
269 | # Select if arch has its private alloc_task_struct() function |
270 | config ARCH_TASK_STRUCT_ALLOCATOR | |
271 | bool | |
272 | ||
5905429a KC |
273 | config HAVE_ARCH_THREAD_STRUCT_WHITELIST |
274 | bool | |
275 | depends on !ARCH_TASK_STRUCT_ALLOCATOR | |
276 | help | |
277 | An architecture should select this to provide hardened usercopy | |
278 | knowledge about what region of the thread_struct should be | |
279 | whitelisted for copying to userspace. Normally this is only the | |
280 | FPU registers. Specifically, arch_thread_struct_whitelist() | |
281 | should be implemented. Without this, the entire thread_struct | |
282 | field in task_struct will be left whitelisted. | |
283 | ||
b235beea LT |
284 | # Select if arch has its private alloc_thread_stack() function |
285 | config ARCH_THREAD_STACK_ALLOCATOR | |
f5e10287 TG |
286 | bool |
287 | ||
5aaeb5c0 IM |
288 | # Select if arch wants to size task_struct dynamically via arch_task_struct_size: |
289 | config ARCH_WANTS_DYNAMIC_TASK_STRUCT | |
290 | bool | |
291 | ||
942fa985 YN |
292 | config ARCH_32BIT_OFF_T |
293 | bool | |
294 | depends on !64BIT | |
295 | help | |
296 | All new 32-bit architectures should have 64-bit off_t type on | |
297 | userspace side which corresponds to the loff_t kernel type. This | |
298 | is the requirement for modern ABIs. Some existing architectures | |
299 | still support 32-bit off_t. This option is enabled for all such | |
300 | architectures explicitly. | |
301 | ||
2ff2b7ec MY |
302 | config HAVE_ASM_MODVERSIONS |
303 | bool | |
304 | help | |
305 | This symbol should be selected by an architecure if it provides | |
306 | <asm/asm-prototypes.h> to support the module versioning for symbols | |
307 | exported from assembly code. | |
308 | ||
f850c30c HC |
309 | config HAVE_REGS_AND_STACK_ACCESS_API |
310 | bool | |
e01292b1 HC |
311 | help |
312 | This symbol should be selected by an architecure if it supports | |
313 | the API needed to access registers and stack entries from pt_regs, | |
314 | declared in asm/ptrace.h | |
315 | For example the kprobes-based event tracer needs this API. | |
f850c30c | 316 | |
d7822b1e MD |
317 | config HAVE_RSEQ |
318 | bool | |
319 | depends on HAVE_REGS_AND_STACK_ACCESS_API | |
320 | help | |
321 | This symbol should be selected by an architecture if it | |
322 | supports an implementation of restartable sequences. | |
323 | ||
3c88ee19 MH |
324 | config HAVE_FUNCTION_ARG_ACCESS_API |
325 | bool | |
326 | help | |
327 | This symbol should be selected by an architecure if it supports | |
328 | the API needed to access function arguments from pt_regs, | |
329 | declared in asm/ptrace.h | |
330 | ||
9483a578 | 331 | config HAVE_CLK |
9ba16087 | 332 | bool |
9483a578 DB |
333 | help |
334 | The <linux/clk.h> calls support software clock gating and | |
335 | thus are a key power management tool on many systems. | |
336 | ||
62a038d3 P |
337 | config HAVE_HW_BREAKPOINT |
338 | bool | |
99e8c5a3 | 339 | depends on PERF_EVENTS |
62a038d3 | 340 | |
0102752e FW |
341 | config HAVE_MIXED_BREAKPOINTS_REGS |
342 | bool | |
343 | depends on HAVE_HW_BREAKPOINT | |
344 | help | |
345 | Depending on the arch implementation of hardware breakpoints, | |
346 | some of them have separate registers for data and instruction | |
347 | breakpoints addresses, others have mixed registers to store | |
348 | them but define the access type in a control register. | |
349 | Select this option if your arch implements breakpoints under the | |
350 | latter fashion. | |
351 | ||
7c68af6e AK |
352 | config HAVE_USER_RETURN_NOTIFIER |
353 | bool | |
a1922ed6 | 354 | |
c01d4323 FW |
355 | config HAVE_PERF_EVENTS_NMI |
356 | bool | |
23637d47 FW |
357 | help |
358 | System hardware can generate an NMI using the perf event | |
359 | subsystem. Also has support for calculating CPU cycle events | |
360 | to determine how many clock cycles in a given period. | |
c01d4323 | 361 | |
05a4a952 NP |
362 | config HAVE_HARDLOCKUP_DETECTOR_PERF |
363 | bool | |
364 | depends on HAVE_PERF_EVENTS_NMI | |
365 | help | |
366 | The arch chooses to use the generic perf-NMI-based hardlockup | |
367 | detector. Must define HAVE_PERF_EVENTS_NMI. | |
368 | ||
369 | config HAVE_NMI_WATCHDOG | |
370 | depends on HAVE_NMI | |
371 | bool | |
372 | help | |
373 | The arch provides a low level NMI watchdog. It provides | |
374 | asm/nmi.h, and defines its own arch_touch_nmi_watchdog(). | |
375 | ||
376 | config HAVE_HARDLOCKUP_DETECTOR_ARCH | |
377 | bool | |
378 | select HAVE_NMI_WATCHDOG | |
379 | help | |
380 | The arch chooses to provide its own hardlockup detector, which is | |
381 | a superset of the HAVE_NMI_WATCHDOG. It also conforms to config | |
382 | interfaces and parameters provided by hardlockup detector subsystem. | |
383 | ||
c5e63197 JO |
384 | config HAVE_PERF_REGS |
385 | bool | |
386 | help | |
387 | Support selective register dumps for perf events. This includes | |
388 | bit-mapping of each registers and a unique architecture id. | |
389 | ||
c5ebcedb JO |
390 | config HAVE_PERF_USER_STACK_DUMP |
391 | bool | |
392 | help | |
393 | Support user stack dumps for perf event samples. This needs | |
394 | access to the user stack pointer which is not unified across | |
395 | architectures. | |
396 | ||
bf5438fc JB |
397 | config HAVE_ARCH_JUMP_LABEL |
398 | bool | |
399 | ||
50ff18ab AB |
400 | config HAVE_ARCH_JUMP_LABEL_RELATIVE |
401 | bool | |
402 | ||
0d6e24d4 PZ |
403 | config MMU_GATHER_TABLE_FREE |
404 | bool | |
405 | ||
ff2e6d72 | 406 | config MMU_GATHER_RCU_TABLE_FREE |
26723911 | 407 | bool |
0d6e24d4 | 408 | select MMU_GATHER_TABLE_FREE |
26723911 | 409 | |
3af4bd03 | 410 | config MMU_GATHER_PAGE_SIZE |
ed6a7935 PZ |
411 | bool |
412 | ||
27796d03 PZ |
413 | config MMU_GATHER_NO_RANGE |
414 | bool | |
415 | ||
580a586c | 416 | config MMU_GATHER_NO_GATHER |
952a31c9 | 417 | bool |
0d6e24d4 | 418 | depends on MMU_GATHER_TABLE_FREE |
952a31c9 | 419 | |
df013ffb HY |
420 | config ARCH_HAVE_NMI_SAFE_CMPXCHG |
421 | bool | |
422 | ||
43570fd2 HC |
423 | config HAVE_ALIGNED_STRUCT_PAGE |
424 | bool | |
425 | help | |
426 | This makes sure that struct pages are double word aligned and that | |
427 | e.g. the SLUB allocator can perform double word atomic operations | |
428 | on a struct page for better performance. However selecting this | |
429 | might increase the size of a struct page by a word. | |
430 | ||
4156153c HC |
431 | config HAVE_CMPXCHG_LOCAL |
432 | bool | |
433 | ||
2565409f HC |
434 | config HAVE_CMPXCHG_DOUBLE |
435 | bool | |
436 | ||
77e58496 PM |
437 | config ARCH_WEAK_RELEASE_ACQUIRE |
438 | bool | |
439 | ||
c1d7e01d WD |
440 | config ARCH_WANT_IPC_PARSE_VERSION |
441 | bool | |
442 | ||
443 | config ARCH_WANT_COMPAT_IPC_PARSE_VERSION | |
444 | bool | |
445 | ||
48b25c43 | 446 | config ARCH_WANT_OLD_COMPAT_IPC |
c1d7e01d | 447 | select ARCH_WANT_COMPAT_IPC_PARSE_VERSION |
48b25c43 CM |
448 | bool |
449 | ||
e2cfabdf WD |
450 | config HAVE_ARCH_SECCOMP_FILTER |
451 | bool | |
452 | help | |
fb0fadf9 | 453 | An arch should select this symbol if it provides all of these things: |
bb6ea430 WD |
454 | - syscall_get_arch() |
455 | - syscall_get_arguments() | |
456 | - syscall_rollback() | |
457 | - syscall_set_return_value() | |
fb0fadf9 WD |
458 | - SIGSYS siginfo_t support |
459 | - secure_computing is called from a ptrace_event()-safe context | |
460 | - secure_computing return value is checked and a return value of -1 | |
461 | results in the system call being skipped immediately. | |
48dc92b9 | 462 | - seccomp syscall wired up |
e2cfabdf WD |
463 | |
464 | config SECCOMP_FILTER | |
465 | def_bool y | |
466 | depends on HAVE_ARCH_SECCOMP_FILTER && SECCOMP && NET | |
467 | help | |
468 | Enable tasks to build secure computing environments defined | |
469 | in terms of Berkeley Packet Filter programs which implement | |
470 | task-defined system call filtering polices. | |
471 | ||
5fb94e9c | 472 | See Documentation/userspace-api/seccomp_filter.rst for details. |
e2cfabdf | 473 | |
afaef01c AP |
474 | config HAVE_ARCH_STACKLEAK |
475 | bool | |
476 | help | |
477 | An architecture should select this if it has the code which | |
478 | fills the used part of the kernel stack with the STACKLEAK_POISON | |
479 | value before returning from system calls. | |
480 | ||
d148eac0 | 481 | config HAVE_STACKPROTECTOR |
19952a92 KC |
482 | bool |
483 | help | |
484 | An arch should select this symbol if: | |
19952a92 KC |
485 | - it has implemented a stack canary (e.g. __stack_chk_guard) |
486 | ||
2a61f474 MY |
487 | config CC_HAS_STACKPROTECTOR_NONE |
488 | def_bool $(cc-option,-fno-stack-protector) | |
489 | ||
050e9baa | 490 | config STACKPROTECTOR |
2a61f474 | 491 | bool "Stack Protector buffer overflow detection" |
d148eac0 | 492 | depends on HAVE_STACKPROTECTOR |
2a61f474 MY |
493 | depends on $(cc-option,-fstack-protector) |
494 | default y | |
19952a92 | 495 | help |
8779657d | 496 | This option turns on the "stack-protector" GCC feature. This |
19952a92 KC |
497 | feature puts, at the beginning of functions, a canary value on |
498 | the stack just before the return address, and validates | |
499 | the value just before actually returning. Stack based buffer | |
500 | overflows (that need to overwrite this return address) now also | |
501 | overwrite the canary, which gets detected and the attack is then | |
502 | neutralized via a kernel panic. | |
503 | ||
8779657d KC |
504 | Functions will have the stack-protector canary logic added if they |
505 | have an 8-byte or larger character array on the stack. | |
506 | ||
19952a92 | 507 | This feature requires gcc version 4.2 or above, or a distribution |
8779657d KC |
508 | gcc with the feature backported ("-fstack-protector"). |
509 | ||
510 | On an x86 "defconfig" build, this feature adds canary checks to | |
511 | about 3% of all kernel functions, which increases kernel code size | |
512 | by about 0.3%. | |
513 | ||
050e9baa | 514 | config STACKPROTECTOR_STRONG |
2a61f474 | 515 | bool "Strong Stack Protector" |
050e9baa | 516 | depends on STACKPROTECTOR |
2a61f474 MY |
517 | depends on $(cc-option,-fstack-protector-strong) |
518 | default y | |
8779657d KC |
519 | help |
520 | Functions will have the stack-protector canary logic added in any | |
521 | of the following conditions: | |
522 | ||
523 | - local variable's address used as part of the right hand side of an | |
524 | assignment or function argument | |
525 | - local variable is an array (or union containing an array), | |
526 | regardless of array type or length | |
527 | - uses register local variables | |
528 | ||
529 | This feature requires gcc version 4.9 or above, or a distribution | |
530 | gcc with the feature backported ("-fstack-protector-strong"). | |
531 | ||
532 | On an x86 "defconfig" build, this feature adds canary checks to | |
533 | about 20% of all kernel functions, which increases the kernel code | |
534 | size by about 2%. | |
535 | ||
0f60a8ef KC |
536 | config HAVE_ARCH_WITHIN_STACK_FRAMES |
537 | bool | |
538 | help | |
539 | An architecture should select this if it can walk the kernel stack | |
540 | frames to determine if an object is part of either the arguments | |
541 | or local variables (i.e. that it excludes saved return addresses, | |
542 | and similar) by implementing an inline arch_within_stack_frames(), | |
543 | which is used by CONFIG_HARDENED_USERCOPY. | |
544 | ||
91d1aa43 | 545 | config HAVE_CONTEXT_TRACKING |
2b1d5024 FW |
546 | bool |
547 | help | |
91d1aa43 FW |
548 | Provide kernel/user boundaries probes necessary for subsystems |
549 | that need it, such as userspace RCU extended quiescent state. | |
490f561b FW |
550 | Syscalls need to be wrapped inside user_exit()-user_enter(), either |
551 | optimized behind static key or through the slow path using TIF_NOHZ | |
552 | flag. Exceptions handlers must be wrapped as well. Irqs are already | |
553 | protected inside rcu_irq_enter/rcu_irq_exit() but preemption or signal | |
554 | handling on irq exit still need to be protected. | |
555 | ||
556 | config HAVE_TIF_NOHZ | |
557 | bool | |
558 | help | |
559 | Arch relies on TIF_NOHZ and syscall slow path to implement context | |
560 | tracking calls to user_enter()/user_exit(). | |
2b1d5024 | 561 | |
b952741c FW |
562 | config HAVE_VIRT_CPU_ACCOUNTING |
563 | bool | |
564 | ||
40565b5a SG |
565 | config ARCH_HAS_SCALED_CPUTIME |
566 | bool | |
567 | ||
554b0004 KH |
568 | config HAVE_VIRT_CPU_ACCOUNTING_GEN |
569 | bool | |
570 | default y if 64BIT | |
571 | help | |
572 | With VIRT_CPU_ACCOUNTING_GEN, cputime_t becomes 64-bit. | |
573 | Before enabling this option, arch code must be audited | |
574 | to ensure there are no races in concurrent read/write of | |
575 | cputime_t. For example, reading/writing 64-bit cputime_t on | |
576 | some 32-bit arches may require multiple accesses, so proper | |
577 | locking is needed to protect against concurrent accesses. | |
578 | ||
579 | ||
fdf9c356 FW |
580 | config HAVE_IRQ_TIME_ACCOUNTING |
581 | bool | |
582 | help | |
583 | Archs need to ensure they use a high enough resolution clock to | |
584 | support irq time accounting and then call enable_sched_clock_irqtime(). | |
585 | ||
2c91bd4a JFG |
586 | config HAVE_MOVE_PMD |
587 | bool | |
588 | help | |
589 | Archs that select this are able to move page tables at the PMD level. | |
590 | ||
15626062 GS |
591 | config HAVE_ARCH_TRANSPARENT_HUGEPAGE |
592 | bool | |
593 | ||
a00cc7d9 MW |
594 | config HAVE_ARCH_TRANSPARENT_HUGEPAGE_PUD |
595 | bool | |
596 | ||
0ddab1d2 TK |
597 | config HAVE_ARCH_HUGE_VMAP |
598 | bool | |
599 | ||
3876d4a3 AG |
600 | config ARCH_WANT_HUGE_PMD_SHARE |
601 | bool | |
602 | ||
0f8975ec PE |
603 | config HAVE_ARCH_SOFT_DIRTY |
604 | bool | |
605 | ||
786d35d4 DH |
606 | config HAVE_MOD_ARCH_SPECIFIC |
607 | bool | |
608 | help | |
609 | The arch uses struct mod_arch_specific to store data. Many arches | |
610 | just need a simple module loader without arch specific data - those | |
611 | should not enable this. | |
612 | ||
613 | config MODULES_USE_ELF_RELA | |
614 | bool | |
615 | help | |
616 | Modules only use ELF RELA relocations. Modules with ELF REL | |
617 | relocations will give an error. | |
618 | ||
619 | config MODULES_USE_ELF_REL | |
620 | bool | |
621 | help | |
622 | Modules only use ELF REL relocations. Modules with ELF RELA | |
623 | relocations will give an error. | |
624 | ||
cc1f0274 FW |
625 | config HAVE_IRQ_EXIT_ON_IRQ_STACK |
626 | bool | |
627 | help | |
628 | Architecture doesn't only execute the irq handler on the irq stack | |
629 | but also irq_exit(). This way we can process softirqs on this irq | |
630 | stack instead of switching to a new one when we call __do_softirq() | |
631 | in the end of an hardirq. | |
632 | This spares a stack switch and improves cache usage on softirq | |
633 | processing. | |
634 | ||
235a8f02 KS |
635 | config PGTABLE_LEVELS |
636 | int | |
637 | default 2 | |
638 | ||
2b68f6ca KC |
639 | config ARCH_HAS_ELF_RANDOMIZE |
640 | bool | |
641 | help | |
642 | An architecture supports choosing randomized locations for | |
643 | stack, mmap, brk, and ET_DYN. Defined functions: | |
644 | - arch_mmap_rnd() | |
204db6ed | 645 | - arch_randomize_brk() |
2b68f6ca | 646 | |
d07e2259 DC |
647 | config HAVE_ARCH_MMAP_RND_BITS |
648 | bool | |
649 | help | |
650 | An arch should select this symbol if it supports setting a variable | |
651 | number of bits for use in establishing the base address for mmap | |
652 | allocations, has MMU enabled and provides values for both: | |
653 | - ARCH_MMAP_RND_BITS_MIN | |
654 | - ARCH_MMAP_RND_BITS_MAX | |
655 | ||
5f56a5df JS |
656 | config HAVE_EXIT_THREAD |
657 | bool | |
658 | help | |
659 | An architecture implements exit_thread. | |
660 | ||
d07e2259 DC |
661 | config ARCH_MMAP_RND_BITS_MIN |
662 | int | |
663 | ||
664 | config ARCH_MMAP_RND_BITS_MAX | |
665 | int | |
666 | ||
667 | config ARCH_MMAP_RND_BITS_DEFAULT | |
668 | int | |
669 | ||
670 | config ARCH_MMAP_RND_BITS | |
671 | int "Number of bits to use for ASLR of mmap base address" if EXPERT | |
672 | range ARCH_MMAP_RND_BITS_MIN ARCH_MMAP_RND_BITS_MAX | |
673 | default ARCH_MMAP_RND_BITS_DEFAULT if ARCH_MMAP_RND_BITS_DEFAULT | |
674 | default ARCH_MMAP_RND_BITS_MIN | |
675 | depends on HAVE_ARCH_MMAP_RND_BITS | |
676 | help | |
677 | This value can be used to select the number of bits to use to | |
678 | determine the random offset to the base address of vma regions | |
679 | resulting from mmap allocations. This value will be bounded | |
680 | by the architecture's minimum and maximum supported values. | |
681 | ||
682 | This value can be changed after boot using the | |
683 | /proc/sys/vm/mmap_rnd_bits tunable | |
684 | ||
685 | config HAVE_ARCH_MMAP_RND_COMPAT_BITS | |
686 | bool | |
687 | help | |
688 | An arch should select this symbol if it supports running applications | |
689 | in compatibility mode, supports setting a variable number of bits for | |
690 | use in establishing the base address for mmap allocations, has MMU | |
691 | enabled and provides values for both: | |
692 | - ARCH_MMAP_RND_COMPAT_BITS_MIN | |
693 | - ARCH_MMAP_RND_COMPAT_BITS_MAX | |
694 | ||
695 | config ARCH_MMAP_RND_COMPAT_BITS_MIN | |
696 | int | |
697 | ||
698 | config ARCH_MMAP_RND_COMPAT_BITS_MAX | |
699 | int | |
700 | ||
701 | config ARCH_MMAP_RND_COMPAT_BITS_DEFAULT | |
702 | int | |
703 | ||
704 | config ARCH_MMAP_RND_COMPAT_BITS | |
705 | int "Number of bits to use for ASLR of mmap base address for compatible applications" if EXPERT | |
706 | range ARCH_MMAP_RND_COMPAT_BITS_MIN ARCH_MMAP_RND_COMPAT_BITS_MAX | |
707 | default ARCH_MMAP_RND_COMPAT_BITS_DEFAULT if ARCH_MMAP_RND_COMPAT_BITS_DEFAULT | |
708 | default ARCH_MMAP_RND_COMPAT_BITS_MIN | |
709 | depends on HAVE_ARCH_MMAP_RND_COMPAT_BITS | |
710 | help | |
711 | This value can be used to select the number of bits to use to | |
712 | determine the random offset to the base address of vma regions | |
713 | resulting from mmap allocations for compatible applications This | |
714 | value will be bounded by the architecture's minimum and maximum | |
715 | supported values. | |
716 | ||
717 | This value can be changed after boot using the | |
718 | /proc/sys/vm/mmap_rnd_compat_bits tunable | |
719 | ||
1b028f78 DS |
720 | config HAVE_ARCH_COMPAT_MMAP_BASES |
721 | bool | |
722 | help | |
723 | This allows 64bit applications to invoke 32-bit mmap() syscall | |
724 | and vice-versa 32-bit applications to call 64-bit mmap(). | |
725 | Required for applications doing different bitness syscalls. | |
726 | ||
67f3977f AG |
727 | # This allows to use a set of generic functions to determine mmap base |
728 | # address by giving priority to top-down scheme only if the process | |
729 | # is not in legacy mode (compat task, unlimited stack size or | |
730 | # sysctl_legacy_va_layout). | |
731 | # Architecture that selects this option can provide its own version of: | |
732 | # - STACK_RND_MASK | |
733 | config ARCH_WANT_DEFAULT_TOPDOWN_MMAP_LAYOUT | |
734 | bool | |
735 | depends on MMU | |
e7142bf5 | 736 | select ARCH_HAS_ELF_RANDOMIZE |
67f3977f | 737 | |
3033f14a JT |
738 | config HAVE_COPY_THREAD_TLS |
739 | bool | |
740 | help | |
741 | Architecture provides copy_thread_tls to accept tls argument via | |
742 | normal C parameter passing, rather than extracting the syscall | |
743 | argument from pt_regs. | |
744 | ||
b9ab5ebb JP |
745 | config HAVE_STACK_VALIDATION |
746 | bool | |
747 | help | |
748 | Architecture supports the 'objtool check' host tool command, which | |
749 | performs compile-time stack metadata validation. | |
750 | ||
af085d90 JP |
751 | config HAVE_RELIABLE_STACKTRACE |
752 | bool | |
753 | help | |
140d7e88 MB |
754 | Architecture has either save_stack_trace_tsk_reliable() or |
755 | arch_stack_walk_reliable() function which only returns a stack trace | |
756 | if it can guarantee the trace is reliable. | |
af085d90 | 757 | |
468a9428 GS |
758 | config HAVE_ARCH_HASH |
759 | bool | |
760 | default n | |
761 | help | |
762 | If this is set, the architecture provides an <asm/hash.h> | |
763 | file which provides platform-specific implementations of some | |
764 | functions in <linux/hash.h> or fs/namei.c. | |
765 | ||
666047fe FT |
766 | config HAVE_ARCH_NVRAM_OPS |
767 | bool | |
768 | ||
3a495511 WBG |
769 | config ISA_BUS_API |
770 | def_bool ISA | |
771 | ||
d2125043 AV |
772 | # |
773 | # ABI hall of shame | |
774 | # | |
775 | config CLONE_BACKWARDS | |
776 | bool | |
777 | help | |
778 | Architecture has tls passed as the 4th argument of clone(2), | |
779 | not the 5th one. | |
780 | ||
781 | config CLONE_BACKWARDS2 | |
782 | bool | |
783 | help | |
784 | Architecture has the first two arguments of clone(2) swapped. | |
785 | ||
dfa9771a MS |
786 | config CLONE_BACKWARDS3 |
787 | bool | |
788 | help | |
789 | Architecture has tls passed as the 3rd argument of clone(2), | |
790 | not the 5th one. | |
791 | ||
eaca6eae AV |
792 | config ODD_RT_SIGACTION |
793 | bool | |
794 | help | |
795 | Architecture has unusual rt_sigaction(2) arguments | |
796 | ||
0a0e8cdf AV |
797 | config OLD_SIGSUSPEND |
798 | bool | |
799 | help | |
800 | Architecture has old sigsuspend(2) syscall, of one-argument variety | |
801 | ||
802 | config OLD_SIGSUSPEND3 | |
803 | bool | |
804 | help | |
805 | Even weirder antique ABI - three-argument sigsuspend(2) | |
806 | ||
495dfbf7 AV |
807 | config OLD_SIGACTION |
808 | bool | |
809 | help | |
810 | Architecture has old sigaction(2) syscall. Nope, not the same | |
811 | as OLD_SIGSUSPEND | OLD_SIGSUSPEND3 - alpha has sigsuspend(2), | |
812 | but fairly different variant of sigaction(2), thanks to OSF/1 | |
813 | compatibility... | |
814 | ||
815 | config COMPAT_OLD_SIGACTION | |
816 | bool | |
817 | ||
17435e5f | 818 | config COMPAT_32BIT_TIME |
942437c9 AB |
819 | bool "Provide system calls for 32-bit time_t" |
820 | default !64BIT || COMPAT | |
17435e5f DD |
821 | help |
822 | This enables 32 bit time_t support in addition to 64 bit time_t support. | |
823 | This is relevant on all 32-bit architectures, and 64-bit architectures | |
824 | as part of compat syscall handling. | |
825 | ||
87a4c375 CH |
826 | config ARCH_NO_PREEMPT |
827 | bool | |
828 | ||
a50a3f4b TG |
829 | config ARCH_SUPPORTS_RT |
830 | bool | |
831 | ||
fff7fb0b ZZ |
832 | config CPU_NO_EFFICIENT_FFS |
833 | def_bool n | |
834 | ||
ba14a194 AL |
835 | config HAVE_ARCH_VMAP_STACK |
836 | def_bool n | |
837 | help | |
838 | An arch should select this symbol if it can support kernel stacks | |
839 | in vmalloc space. This means: | |
840 | ||
841 | - vmalloc space must be large enough to hold many kernel stacks. | |
842 | This may rule out many 32-bit architectures. | |
843 | ||
844 | - Stacks in vmalloc space need to work reliably. For example, if | |
845 | vmap page tables are created on demand, either this mechanism | |
846 | needs to work while the stack points to a virtual address with | |
847 | unpopulated page tables or arch code (switch_to() and switch_mm(), | |
848 | most likely) needs to ensure that the stack's page table entries | |
849 | are populated before running on a possibly unpopulated stack. | |
850 | ||
851 | - If the stack overflows into a guard page, something reasonable | |
852 | should happen. The definition of "reasonable" is flexible, but | |
853 | instantly rebooting without logging anything would be unfriendly. | |
854 | ||
855 | config VMAP_STACK | |
856 | default y | |
857 | bool "Use a virtually-mapped stack" | |
eafb149e DA |
858 | depends on HAVE_ARCH_VMAP_STACK |
859 | depends on !KASAN || KASAN_VMALLOC | |
ba14a194 AL |
860 | ---help--- |
861 | Enable this if you want the use virtually-mapped kernel stacks | |
862 | with guard pages. This causes kernel stack overflows to be | |
863 | caught immediately rather than causing difficult-to-diagnose | |
864 | corruption. | |
865 | ||
eafb149e DA |
866 | To use this with KASAN, the architecture must support backing |
867 | virtual mappings with real shadow memory, and KASAN_VMALLOC must | |
868 | be enabled. | |
ba14a194 | 869 | |
ad21fc4f LA |
870 | config ARCH_OPTIONAL_KERNEL_RWX |
871 | def_bool n | |
872 | ||
873 | config ARCH_OPTIONAL_KERNEL_RWX_DEFAULT | |
874 | def_bool n | |
875 | ||
876 | config ARCH_HAS_STRICT_KERNEL_RWX | |
877 | def_bool n | |
878 | ||
0f5bf6d0 | 879 | config STRICT_KERNEL_RWX |
ad21fc4f LA |
880 | bool "Make kernel text and rodata read-only" if ARCH_OPTIONAL_KERNEL_RWX |
881 | depends on ARCH_HAS_STRICT_KERNEL_RWX | |
882 | default !ARCH_OPTIONAL_KERNEL_RWX || ARCH_OPTIONAL_KERNEL_RWX_DEFAULT | |
883 | help | |
884 | If this is set, kernel text and rodata memory will be made read-only, | |
885 | and non-text memory will be made non-executable. This provides | |
886 | protection against certain security exploits (e.g. executing the heap | |
887 | or modifying text) | |
888 | ||
889 | These features are considered standard security practice these days. | |
890 | You should say Y here in almost all cases. | |
891 | ||
892 | config ARCH_HAS_STRICT_MODULE_RWX | |
893 | def_bool n | |
894 | ||
0f5bf6d0 | 895 | config STRICT_MODULE_RWX |
ad21fc4f LA |
896 | bool "Set loadable kernel module data as NX and text as RO" if ARCH_OPTIONAL_KERNEL_RWX |
897 | depends on ARCH_HAS_STRICT_MODULE_RWX && MODULES | |
898 | default !ARCH_OPTIONAL_KERNEL_RWX || ARCH_OPTIONAL_KERNEL_RWX_DEFAULT | |
899 | help | |
900 | If this is set, module text and rodata memory will be made read-only, | |
901 | and non-text memory will be made non-executable. This provides | |
902 | protection against certain security exploits (e.g. writing to text) | |
903 | ||
ea8c64ac CH |
904 | # select if the architecture provides an asm/dma-direct.h header |
905 | config ARCH_HAS_PHYS_TO_DMA | |
906 | bool | |
907 | ||
04f264d3 PB |
908 | config HAVE_ARCH_COMPILER_H |
909 | bool | |
910 | help | |
911 | An architecture can select this if it provides an | |
912 | asm/compiler.h header that should be included after | |
913 | linux/compiler-*.h in order to override macro definitions that those | |
914 | headers generally provide. | |
915 | ||
271ca788 AB |
916 | config HAVE_ARCH_PREL32_RELOCATIONS |
917 | bool | |
918 | help | |
919 | May be selected by an architecture if it supports place-relative | |
920 | 32-bit relocations, both in the toolchain and in the module loader, | |
921 | in which case relative references can be used in special sections | |
922 | for PCI fixup, initcalls etc which are only half the size on 64 bit | |
923 | architectures, and don't require runtime relocation on relocatable | |
924 | kernels. | |
925 | ||
ce9084ba AB |
926 | config ARCH_USE_MEMREMAP_PROT |
927 | bool | |
928 | ||
fb346fd9 WL |
929 | config LOCK_EVENT_COUNTS |
930 | bool "Locking event counts collection" | |
931 | depends on DEBUG_FS | |
fb346fd9 WL |
932 | ---help--- |
933 | Enable light-weight counting of various locking related events | |
934 | in the system with minimal performance impact. This reduces | |
935 | the chance of application behavior change because of timing | |
936 | differences. The counts are reported via debugfs. | |
937 | ||
5cf896fb PC |
938 | # Select if the architecture has support for applying RELR relocations. |
939 | config ARCH_HAS_RELR | |
940 | bool | |
941 | ||
942 | config RELR | |
943 | bool "Use RELR relocation packing" | |
944 | depends on ARCH_HAS_RELR && TOOLS_SUPPORT_RELR | |
945 | default y | |
946 | help | |
947 | Store the kernel's dynamic relocations in the RELR relocation packing | |
948 | format. Requires a compatible linker (LLD supports this feature), as | |
949 | well as compatible NM and OBJCOPY utilities (llvm-nm and llvm-objcopy | |
950 | are compatible). | |
951 | ||
0c9c1d56 TJB |
952 | config ARCH_HAS_MEM_ENCRYPT |
953 | bool | |
954 | ||
0e242208 HN |
955 | config HAVE_SPARSE_SYSCALL_NR |
956 | bool | |
957 | help | |
958 | An architecture should select this if its syscall numbering is sparse | |
959 | to save space. For example, MIPS architecture has a syscall array with | |
960 | entries at 4000, 5000 and 6000 locations. This option turns on syscall | |
961 | related optimizations for a given architecture. | |
962 | ||
2521f2c2 | 963 | source "kernel/gcov/Kconfig" |
45332b1b MY |
964 | |
965 | source "scripts/gcc-plugins/Kconfig" | |
fa1b5d09 | 966 | |
22471e13 | 967 | endmenu |