Commit | Line | Data |
---|---|---|
b2441318 | 1 | # SPDX-License-Identifier: GPL-2.0 |
fb32e03f MD |
2 | # |
3 | # General architecture dependent options | |
4 | # | |
125e5645 | 5 | |
692f66f2 HB |
6 | config CRASH_CORE |
7 | bool | |
8 | ||
2965faa5 | 9 | config KEXEC_CORE |
692f66f2 | 10 | select CRASH_CORE |
2965faa5 DY |
11 | bool |
12 | ||
467d2782 TJB |
13 | config HAVE_IMA_KEXEC |
14 | bool | |
15 | ||
c5ac43ee TG |
16 | config HOTPLUG_SMT |
17 | bool | |
18 | ||
125e5645 | 19 | config OPROFILE |
b309a294 | 20 | tristate "OProfile system profiling" |
125e5645 MD |
21 | depends on PROFILING |
22 | depends on HAVE_OPROFILE | |
d69d59f4 | 23 | select RING_BUFFER |
9a5963eb | 24 | select RING_BUFFER_ALLOW_SWAP |
125e5645 MD |
25 | help |
26 | OProfile is a profiling system capable of profiling the | |
27 | whole system, include the kernel, kernel modules, libraries, | |
28 | and applications. | |
29 | ||
30 | If unsure, say N. | |
31 | ||
4d4036e0 JY |
32 | config OPROFILE_EVENT_MULTIPLEX |
33 | bool "OProfile multiplexing support (EXPERIMENTAL)" | |
34 | default n | |
35 | depends on OPROFILE && X86 | |
36 | help | |
37 | The number of hardware counters is limited. The multiplexing | |
38 | feature enables OProfile to gather more events than counters | |
39 | are provided by the hardware. This is realized by switching | |
9332ef9d | 40 | between events at a user specified time interval. |
4d4036e0 JY |
41 | |
42 | If unsure, say N. | |
43 | ||
125e5645 | 44 | config HAVE_OPROFILE |
9ba16087 | 45 | bool |
125e5645 | 46 | |
dcfce4a0 RR |
47 | config OPROFILE_NMI_TIMER |
48 | def_bool y | |
af9feebe | 49 | depends on PERF_EVENTS && HAVE_PERF_EVENTS_NMI && !PPC64 |
dcfce4a0 | 50 | |
125e5645 MD |
51 | config KPROBES |
52 | bool "Kprobes" | |
05ed160e | 53 | depends on MODULES |
125e5645 | 54 | depends on HAVE_KPROBES |
05ed160e | 55 | select KALLSYMS |
125e5645 MD |
56 | help |
57 | Kprobes allows you to trap at almost any kernel address and | |
58 | execute a callback function. register_kprobe() establishes | |
59 | a probepoint and specifies the callback. Kprobes is useful | |
60 | for kernel debugging, non-intrusive instrumentation and testing. | |
61 | If in doubt, say "N". | |
62 | ||
45f81b1c | 63 | config JUMP_LABEL |
c5905afb | 64 | bool "Optimize very unlikely/likely branches" |
45f81b1c SR |
65 | depends on HAVE_ARCH_JUMP_LABEL |
66 | help | |
c5905afb IM |
67 | This option enables a transparent branch optimization that |
68 | makes certain almost-always-true or almost-always-false branch | |
69 | conditions even cheaper to execute within the kernel. | |
70 | ||
71 | Certain performance-sensitive kernel code, such as trace points, | |
72 | scheduler functionality, networking code and KVM have such | |
73 | branches and include support for this optimization technique. | |
74 | ||
45f81b1c | 75 | If it is detected that the compiler has support for "asm goto", |
c5905afb IM |
76 | the kernel will compile such branches with just a nop |
77 | instruction. When the condition flag is toggled to true, the | |
78 | nop will be converted to a jump instruction to execute the | |
79 | conditional block of instructions. | |
80 | ||
81 | This technique lowers overhead and stress on the branch prediction | |
82 | of the processor and generally makes the kernel faster. The update | |
83 | of the condition is slower, but those are always very rare. | |
45f81b1c | 84 | |
c5905afb IM |
85 | ( On 32-bit x86, the necessary options added to the compiler |
86 | flags may increase the size of the kernel slightly. ) | |
45f81b1c | 87 | |
1987c947 PZ |
88 | config STATIC_KEYS_SELFTEST |
89 | bool "Static key selftest" | |
90 | depends on JUMP_LABEL | |
91 | help | |
92 | Boot time self-test of the branch patching code. | |
93 | ||
afd66255 | 94 | config OPTPROBES |
5cc718b9 MH |
95 | def_bool y |
96 | depends on KPROBES && HAVE_OPTPROBES | |
5715de46 | 97 | select TASKS_RCU if PREEMPT |
afd66255 | 98 | |
e7dbfe34 MH |
99 | config KPROBES_ON_FTRACE |
100 | def_bool y | |
101 | depends on KPROBES && HAVE_KPROBES_ON_FTRACE | |
102 | depends on DYNAMIC_FTRACE_WITH_REGS | |
103 | help | |
104 | If function tracer is enabled and the arch supports full | |
105 | passing of pt_regs to function tracing, then kprobes can | |
106 | optimize on top of function tracing. | |
107 | ||
2b144498 | 108 | config UPROBES |
09294e31 | 109 | def_bool n |
e8f4aa60 | 110 | depends on ARCH_SUPPORTS_UPROBES |
2b144498 | 111 | help |
7b2d81d4 IM |
112 | Uprobes is the user-space counterpart to kprobes: they |
113 | enable instrumentation applications (such as 'perf probe') | |
114 | to establish unintrusive probes in user-space binaries and | |
115 | libraries, by executing handler functions when the probes | |
116 | are hit by user-space applications. | |
117 | ||
118 | ( These probes come in the form of single-byte breakpoints, | |
119 | managed by the kernel and kept transparent to the probed | |
120 | application. ) | |
2b144498 | 121 | |
c19fa94a JH |
122 | config HAVE_64BIT_ALIGNED_ACCESS |
123 | def_bool 64BIT && !HAVE_EFFICIENT_UNALIGNED_ACCESS | |
124 | help | |
125 | Some architectures require 64 bit accesses to be 64 bit | |
126 | aligned, which also requires structs containing 64 bit values | |
127 | to be 64 bit aligned too. This includes some 32 bit | |
128 | architectures which can do 64 bit accesses, as well as 64 bit | |
129 | architectures without unaligned access. | |
130 | ||
131 | This symbol should be selected by an architecture if 64 bit | |
132 | accesses are required to be 64 bit aligned in this way even | |
133 | though it is not a 64 bit architecture. | |
134 | ||
135 | See Documentation/unaligned-memory-access.txt for more | |
136 | information on the topic of unaligned memory accesses. | |
137 | ||
58340a07 | 138 | config HAVE_EFFICIENT_UNALIGNED_ACCESS |
9ba16087 | 139 | bool |
58340a07 JB |
140 | help |
141 | Some architectures are unable to perform unaligned accesses | |
142 | without the use of get_unaligned/put_unaligned. Others are | |
143 | unable to perform such accesses efficiently (e.g. trap on | |
144 | unaligned access and require fixing it up in the exception | |
145 | handler.) | |
146 | ||
147 | This symbol should be selected by an architecture if it can | |
148 | perform unaligned accesses efficiently to allow different | |
149 | code paths to be selected for these cases. Some network | |
150 | drivers, for example, could opt to not fix up alignment | |
151 | problems with received packets if doing so would not help | |
152 | much. | |
153 | ||
154 | See Documentation/unaligned-memory-access.txt for more | |
155 | information on the topic of unaligned memory accesses. | |
156 | ||
cf66bb93 DW |
157 | config ARCH_USE_BUILTIN_BSWAP |
158 | bool | |
159 | help | |
160 | Modern versions of GCC (since 4.4) have builtin functions | |
161 | for handling byte-swapping. Using these, instead of the old | |
162 | inline assembler that the architecture code provides in the | |
163 | __arch_bswapXX() macros, allows the compiler to see what's | |
164 | happening and offers more opportunity for optimisation. In | |
165 | particular, the compiler will be able to combine the byteswap | |
166 | with a nearby load or store and use load-and-swap or | |
167 | store-and-swap instructions if the architecture has them. It | |
168 | should almost *never* result in code which is worse than the | |
169 | hand-coded assembler in <asm/swab.h>. But just in case it | |
170 | does, the use of the builtins is optional. | |
171 | ||
172 | Any architecture with load-and-swap or store-and-swap | |
173 | instructions should set this. And it shouldn't hurt to set it | |
174 | on architectures that don't have such instructions. | |
175 | ||
9edddaa2 AM |
176 | config KRETPROBES |
177 | def_bool y | |
178 | depends on KPROBES && HAVE_KRETPROBES | |
179 | ||
7c68af6e AK |
180 | config USER_RETURN_NOTIFIER |
181 | bool | |
182 | depends on HAVE_USER_RETURN_NOTIFIER | |
183 | help | |
184 | Provide a kernel-internal notification when a cpu is about to | |
185 | switch to user mode. | |
186 | ||
28b2ee20 | 187 | config HAVE_IOREMAP_PROT |
9ba16087 | 188 | bool |
28b2ee20 | 189 | |
125e5645 | 190 | config HAVE_KPROBES |
9ba16087 | 191 | bool |
9edddaa2 AM |
192 | |
193 | config HAVE_KRETPROBES | |
9ba16087 | 194 | bool |
74bc7cee | 195 | |
afd66255 MH |
196 | config HAVE_OPTPROBES |
197 | bool | |
d314d74c | 198 | |
e7dbfe34 MH |
199 | config HAVE_KPROBES_ON_FTRACE |
200 | bool | |
201 | ||
42a0bb3f PM |
202 | config HAVE_NMI |
203 | bool | |
204 | ||
1f5a4ad9 RM |
205 | # |
206 | # An arch should select this if it provides all these things: | |
207 | # | |
208 | # task_pt_regs() in asm/processor.h or asm/ptrace.h | |
209 | # arch_has_single_step() if there is hardware single-step support | |
210 | # arch_has_block_step() if there is hardware block-step support | |
1f5a4ad9 RM |
211 | # asm/syscall.h supplying asm-generic/syscall.h interface |
212 | # linux/regset.h user_regset interfaces | |
213 | # CORE_DUMP_USE_REGSET #define'd in linux/elf.h | |
214 | # TIF_SYSCALL_TRACE calls tracehook_report_syscall_{entry,exit} | |
215 | # TIF_NOTIFY_RESUME calls tracehook_notify_resume() | |
216 | # signal delivery calls tracehook_signal_handler() | |
217 | # | |
218 | config HAVE_ARCH_TRACEHOOK | |
9ba16087 | 219 | bool |
1f5a4ad9 | 220 | |
c64be2bb MS |
221 | config HAVE_DMA_CONTIGUOUS |
222 | bool | |
223 | ||
29d5e047 TG |
224 | config GENERIC_SMP_IDLE_THREAD |
225 | bool | |
226 | ||
485cf5da KH |
227 | config GENERIC_IDLE_POLL_SETUP |
228 | bool | |
229 | ||
6974f0c4 DM |
230 | config ARCH_HAS_FORTIFY_SOURCE |
231 | bool | |
232 | help | |
233 | An architecture should select this when it can successfully | |
234 | build and run with CONFIG_FORTIFY_SOURCE. | |
235 | ||
d2852a22 DB |
236 | # Select if arch has all set_memory_ro/rw/x/nx() functions in asm/cacheflush.h |
237 | config ARCH_HAS_SET_MEMORY | |
238 | bool | |
239 | ||
a6359d1e TG |
240 | # Select if arch init_task initializer is different to init/init_task.c |
241 | config ARCH_INIT_TASK | |
a4a2eb49 TG |
242 | bool |
243 | ||
f5e10287 TG |
244 | # Select if arch has its private alloc_task_struct() function |
245 | config ARCH_TASK_STRUCT_ALLOCATOR | |
246 | bool | |
247 | ||
b235beea LT |
248 | # Select if arch has its private alloc_thread_stack() function |
249 | config ARCH_THREAD_STACK_ALLOCATOR | |
f5e10287 TG |
250 | bool |
251 | ||
5aaeb5c0 IM |
252 | # Select if arch wants to size task_struct dynamically via arch_task_struct_size: |
253 | config ARCH_WANTS_DYNAMIC_TASK_STRUCT | |
254 | bool | |
255 | ||
f850c30c HC |
256 | config HAVE_REGS_AND_STACK_ACCESS_API |
257 | bool | |
e01292b1 HC |
258 | help |
259 | This symbol should be selected by an architecure if it supports | |
260 | the API needed to access registers and stack entries from pt_regs, | |
261 | declared in asm/ptrace.h | |
262 | For example the kprobes-based event tracer needs this API. | |
f850c30c | 263 | |
9483a578 | 264 | config HAVE_CLK |
9ba16087 | 265 | bool |
9483a578 DB |
266 | help |
267 | The <linux/clk.h> calls support software clock gating and | |
268 | thus are a key power management tool on many systems. | |
269 | ||
5ee00bd4 JR |
270 | config HAVE_DMA_API_DEBUG |
271 | bool | |
36cd3c9f | 272 | |
62a038d3 P |
273 | config HAVE_HW_BREAKPOINT |
274 | bool | |
99e8c5a3 | 275 | depends on PERF_EVENTS |
62a038d3 | 276 | |
0102752e FW |
277 | config HAVE_MIXED_BREAKPOINTS_REGS |
278 | bool | |
279 | depends on HAVE_HW_BREAKPOINT | |
280 | help | |
281 | Depending on the arch implementation of hardware breakpoints, | |
282 | some of them have separate registers for data and instruction | |
283 | breakpoints addresses, others have mixed registers to store | |
284 | them but define the access type in a control register. | |
285 | Select this option if your arch implements breakpoints under the | |
286 | latter fashion. | |
287 | ||
7c68af6e AK |
288 | config HAVE_USER_RETURN_NOTIFIER |
289 | bool | |
a1922ed6 | 290 | |
c01d4323 FW |
291 | config HAVE_PERF_EVENTS_NMI |
292 | bool | |
23637d47 FW |
293 | help |
294 | System hardware can generate an NMI using the perf event | |
295 | subsystem. Also has support for calculating CPU cycle events | |
296 | to determine how many clock cycles in a given period. | |
c01d4323 | 297 | |
05a4a952 NP |
298 | config HAVE_HARDLOCKUP_DETECTOR_PERF |
299 | bool | |
300 | depends on HAVE_PERF_EVENTS_NMI | |
301 | help | |
302 | The arch chooses to use the generic perf-NMI-based hardlockup | |
303 | detector. Must define HAVE_PERF_EVENTS_NMI. | |
304 | ||
305 | config HAVE_NMI_WATCHDOG | |
306 | depends on HAVE_NMI | |
307 | bool | |
308 | help | |
309 | The arch provides a low level NMI watchdog. It provides | |
310 | asm/nmi.h, and defines its own arch_touch_nmi_watchdog(). | |
311 | ||
312 | config HAVE_HARDLOCKUP_DETECTOR_ARCH | |
313 | bool | |
314 | select HAVE_NMI_WATCHDOG | |
315 | help | |
316 | The arch chooses to provide its own hardlockup detector, which is | |
317 | a superset of the HAVE_NMI_WATCHDOG. It also conforms to config | |
318 | interfaces and parameters provided by hardlockup detector subsystem. | |
319 | ||
c5e63197 JO |
320 | config HAVE_PERF_REGS |
321 | bool | |
322 | help | |
323 | Support selective register dumps for perf events. This includes | |
324 | bit-mapping of each registers and a unique architecture id. | |
325 | ||
c5ebcedb JO |
326 | config HAVE_PERF_USER_STACK_DUMP |
327 | bool | |
328 | help | |
329 | Support user stack dumps for perf event samples. This needs | |
330 | access to the user stack pointer which is not unified across | |
331 | architectures. | |
332 | ||
bf5438fc JB |
333 | config HAVE_ARCH_JUMP_LABEL |
334 | bool | |
335 | ||
26723911 PZ |
336 | config HAVE_RCU_TABLE_FREE |
337 | bool | |
338 | ||
e9afa7c1 PZ |
339 | config HAVE_RCU_TABLE_INVALIDATE |
340 | bool | |
341 | ||
df013ffb HY |
342 | config ARCH_HAVE_NMI_SAFE_CMPXCHG |
343 | bool | |
344 | ||
43570fd2 HC |
345 | config HAVE_ALIGNED_STRUCT_PAGE |
346 | bool | |
347 | help | |
348 | This makes sure that struct pages are double word aligned and that | |
349 | e.g. the SLUB allocator can perform double word atomic operations | |
350 | on a struct page for better performance. However selecting this | |
351 | might increase the size of a struct page by a word. | |
352 | ||
4156153c HC |
353 | config HAVE_CMPXCHG_LOCAL |
354 | bool | |
355 | ||
2565409f HC |
356 | config HAVE_CMPXCHG_DOUBLE |
357 | bool | |
358 | ||
77e58496 PM |
359 | config ARCH_WEAK_RELEASE_ACQUIRE |
360 | bool | |
361 | ||
c1d7e01d WD |
362 | config ARCH_WANT_IPC_PARSE_VERSION |
363 | bool | |
364 | ||
365 | config ARCH_WANT_COMPAT_IPC_PARSE_VERSION | |
366 | bool | |
367 | ||
48b25c43 | 368 | config ARCH_WANT_OLD_COMPAT_IPC |
c1d7e01d | 369 | select ARCH_WANT_COMPAT_IPC_PARSE_VERSION |
48b25c43 CM |
370 | bool |
371 | ||
e2cfabdf WD |
372 | config HAVE_ARCH_SECCOMP_FILTER |
373 | bool | |
374 | help | |
fb0fadf9 | 375 | An arch should select this symbol if it provides all of these things: |
bb6ea430 WD |
376 | - syscall_get_arch() |
377 | - syscall_get_arguments() | |
378 | - syscall_rollback() | |
379 | - syscall_set_return_value() | |
fb0fadf9 WD |
380 | - SIGSYS siginfo_t support |
381 | - secure_computing is called from a ptrace_event()-safe context | |
382 | - secure_computing return value is checked and a return value of -1 | |
383 | results in the system call being skipped immediately. | |
48dc92b9 | 384 | - seccomp syscall wired up |
e2cfabdf WD |
385 | |
386 | config SECCOMP_FILTER | |
387 | def_bool y | |
388 | depends on HAVE_ARCH_SECCOMP_FILTER && SECCOMP && NET | |
389 | help | |
390 | Enable tasks to build secure computing environments defined | |
391 | in terms of Berkeley Packet Filter programs which implement | |
392 | task-defined system call filtering polices. | |
393 | ||
394 | See Documentation/prctl/seccomp_filter.txt for details. | |
395 | ||
6b90bd4b ER |
396 | config HAVE_GCC_PLUGINS |
397 | bool | |
398 | help | |
399 | An arch should select this symbol if it supports building with | |
400 | GCC plugins. | |
401 | ||
402 | menuconfig GCC_PLUGINS | |
403 | bool "GCC plugins" | |
404 | depends on HAVE_GCC_PLUGINS | |
a519167e | 405 | depends on !COMPILE_TEST |
6b90bd4b ER |
406 | help |
407 | GCC plugins are loadable modules that provide extra features to the | |
408 | compiler. They are useful for runtime instrumentation and static analysis. | |
409 | ||
410 | See Documentation/gcc-plugins.txt for details. | |
411 | ||
0dae776c | 412 | config GCC_PLUGIN_CYC_COMPLEXITY |
215e2aa6 | 413 | bool "Compute the cyclomatic complexity of a function" if EXPERT |
0dae776c | 414 | depends on GCC_PLUGINS |
215e2aa6 | 415 | depends on !COMPILE_TEST |
0dae776c ER |
416 | help |
417 | The complexity M of a function's control flow graph is defined as: | |
418 | M = E - N + 2P | |
419 | where | |
420 | ||
421 | E = the number of edges | |
422 | N = the number of nodes | |
423 | P = the number of connected components (exit nodes). | |
424 | ||
215e2aa6 KC |
425 | Enabling this plugin reports the complexity to stderr during the |
426 | build. It mainly serves as a simple example of how to create a | |
427 | gcc plugin for the kernel. | |
428 | ||
543c37cb ER |
429 | config GCC_PLUGIN_SANCOV |
430 | bool | |
431 | depends on GCC_PLUGINS | |
432 | help | |
433 | This plugin inserts a __sanitizer_cov_trace_pc() call at the start of | |
434 | basic blocks. It supports all gcc versions with plugin support (from | |
435 | gcc-4.5 on). It is based on the commit "Add fuzzing coverage support" | |
436 | by Dmitry Vyukov <dvyukov@google.com>. | |
437 | ||
38addce8 ER |
438 | config GCC_PLUGIN_LATENT_ENTROPY |
439 | bool "Generate some entropy during boot and runtime" | |
440 | depends on GCC_PLUGINS | |
441 | help | |
442 | By saying Y here the kernel will instrument some kernel code to | |
443 | extract some entropy from both original and artificially created | |
444 | program state. This will help especially embedded systems where | |
445 | there is little 'natural' source of entropy normally. The cost | |
446 | is some slowdown of the boot process (about 0.5%) and fork and | |
447 | irq processing. | |
448 | ||
449 | Note that entropy extracted this way is not cryptographically | |
450 | secure! | |
451 | ||
452 | This plugin was ported from grsecurity/PaX. More information at: | |
453 | * https://grsecurity.net/ | |
454 | * https://pax.grsecurity.net/ | |
455 | ||
c61f13ea KC |
456 | config GCC_PLUGIN_STRUCTLEAK |
457 | bool "Force initialization of variables containing userspace addresses" | |
458 | depends on GCC_PLUGINS | |
459 | help | |
f136e090 | 460 | This plugin zero-initializes any structures containing a |
c61f13ea KC |
461 | __user attribute. This can prevent some classes of information |
462 | exposures. | |
463 | ||
464 | This plugin was ported from grsecurity/PaX. More information at: | |
465 | * https://grsecurity.net/ | |
466 | * https://pax.grsecurity.net/ | |
467 | ||
f7dd2507 AB |
468 | config GCC_PLUGIN_STRUCTLEAK_BYREF_ALL |
469 | bool "Force initialize all struct type variables passed by reference" | |
470 | depends on GCC_PLUGIN_STRUCTLEAK | |
471 | help | |
472 | Zero initialize any struct type local variable that may be passed by | |
473 | reference without having been initialized. | |
474 | ||
c61f13ea KC |
475 | config GCC_PLUGIN_STRUCTLEAK_VERBOSE |
476 | bool "Report forcefully initialized variables" | |
477 | depends on GCC_PLUGIN_STRUCTLEAK | |
478 | depends on !COMPILE_TEST | |
479 | help | |
480 | This option will cause a warning to be printed each time the | |
481 | structleak plugin finds a variable it thinks needs to be | |
482 | initialized. Since not all existing initializers are detected | |
483 | by the plugin, this can produce false positive warnings. | |
484 | ||
313dd1b6 KC |
485 | config GCC_PLUGIN_RANDSTRUCT |
486 | bool "Randomize layout of sensitive kernel structures" | |
487 | depends on GCC_PLUGINS | |
488 | select MODVERSIONS if MODULES | |
489 | help | |
9225331b KC |
490 | If you say Y here, the layouts of structures that are entirely |
491 | function pointers (and have not been manually annotated with | |
492 | __no_randomize_layout), or structures that have been explicitly | |
493 | marked with __randomize_layout, will be randomized at compile-time. | |
494 | This can introduce the requirement of an additional information | |
495 | exposure vulnerability for exploits targeting these structure | |
496 | types. | |
313dd1b6 KC |
497 | |
498 | Enabling this feature will introduce some performance impact, | |
499 | slightly increase memory usage, and prevent the use of forensic | |
500 | tools like Volatility against the system (unless the kernel | |
501 | source tree isn't cleaned after kernel installation). | |
502 | ||
503 | The seed used for compilation is located at | |
504 | scripts/gcc-plgins/randomize_layout_seed.h. It remains after | |
505 | a make clean to allow for external modules to be compiled with | |
506 | the existing seed and will be removed by a make mrproper or | |
507 | make distclean. | |
508 | ||
509 | Note that the implementation requires gcc 4.7 or newer. | |
510 | ||
511 | This plugin was ported from grsecurity/PaX. More information at: | |
512 | * https://grsecurity.net/ | |
513 | * https://pax.grsecurity.net/ | |
514 | ||
515 | config GCC_PLUGIN_RANDSTRUCT_PERFORMANCE | |
516 | bool "Use cacheline-aware structure randomization" | |
517 | depends on GCC_PLUGIN_RANDSTRUCT | |
518 | depends on !COMPILE_TEST | |
519 | help | |
520 | If you say Y here, the RANDSTRUCT randomization will make a | |
521 | best effort at restricting randomization to cacheline-sized | |
522 | groups of elements. It will further not randomize bitfields | |
523 | in structures. This reduces the performance hit of RANDSTRUCT | |
524 | at the cost of weakened randomization. | |
525 | ||
19952a92 KC |
526 | config HAVE_CC_STACKPROTECTOR |
527 | bool | |
528 | help | |
529 | An arch should select this symbol if: | |
530 | - its compiler supports the -fstack-protector option | |
531 | - it has implemented a stack canary (e.g. __stack_chk_guard) | |
532 | ||
533 | config CC_STACKPROTECTOR | |
8779657d KC |
534 | def_bool n |
535 | help | |
536 | Set when a stack-protector mode is enabled, so that the build | |
537 | can enable kernel-side support for the GCC feature. | |
538 | ||
539 | choice | |
540 | prompt "Stack Protector buffer overflow detection" | |
19952a92 | 541 | depends on HAVE_CC_STACKPROTECTOR |
8779657d | 542 | default CC_STACKPROTECTOR_NONE |
19952a92 | 543 | help |
8779657d | 544 | This option turns on the "stack-protector" GCC feature. This |
19952a92 KC |
545 | feature puts, at the beginning of functions, a canary value on |
546 | the stack just before the return address, and validates | |
547 | the value just before actually returning. Stack based buffer | |
548 | overflows (that need to overwrite this return address) now also | |
549 | overwrite the canary, which gets detected and the attack is then | |
550 | neutralized via a kernel panic. | |
551 | ||
8779657d KC |
552 | config CC_STACKPROTECTOR_NONE |
553 | bool "None" | |
554 | help | |
555 | Disable "stack-protector" GCC feature. | |
556 | ||
557 | config CC_STACKPROTECTOR_REGULAR | |
558 | bool "Regular" | |
559 | select CC_STACKPROTECTOR | |
560 | help | |
561 | Functions will have the stack-protector canary logic added if they | |
562 | have an 8-byte or larger character array on the stack. | |
563 | ||
19952a92 | 564 | This feature requires gcc version 4.2 or above, or a distribution |
8779657d KC |
565 | gcc with the feature backported ("-fstack-protector"). |
566 | ||
567 | On an x86 "defconfig" build, this feature adds canary checks to | |
568 | about 3% of all kernel functions, which increases kernel code size | |
569 | by about 0.3%. | |
570 | ||
571 | config CC_STACKPROTECTOR_STRONG | |
572 | bool "Strong" | |
573 | select CC_STACKPROTECTOR | |
574 | help | |
575 | Functions will have the stack-protector canary logic added in any | |
576 | of the following conditions: | |
577 | ||
578 | - local variable's address used as part of the right hand side of an | |
579 | assignment or function argument | |
580 | - local variable is an array (or union containing an array), | |
581 | regardless of array type or length | |
582 | - uses register local variables | |
583 | ||
584 | This feature requires gcc version 4.9 or above, or a distribution | |
585 | gcc with the feature backported ("-fstack-protector-strong"). | |
586 | ||
587 | On an x86 "defconfig" build, this feature adds canary checks to | |
588 | about 20% of all kernel functions, which increases the kernel code | |
589 | size by about 2%. | |
590 | ||
591 | endchoice | |
19952a92 | 592 | |
a5967db9 | 593 | config THIN_ARCHIVES |
799c4341 | 594 | def_bool y |
a5967db9 SR |
595 | help |
596 | Select this if the architecture wants to use thin archives | |
597 | instead of ld -r to create the built-in.o files. | |
598 | ||
b67067f1 NP |
599 | config LD_DEAD_CODE_DATA_ELIMINATION |
600 | bool | |
601 | help | |
602 | Select this if the architecture wants to do dead code and | |
603 | data elimination with the linker by compiling with | |
604 | -ffunction-sections -fdata-sections and linking with | |
605 | --gc-sections. | |
606 | ||
607 | This requires that the arch annotates or otherwise protects | |
608 | its external entry points from being discarded. Linker scripts | |
609 | must also merge .text.*, .data.*, and .bss.* correctly into | |
0f4c4af0 NP |
610 | output sections. Care must be taken not to pull in unrelated |
611 | sections (e.g., '.text.init'). Typically '.' in section names | |
612 | is used to distinguish them from label names / C identifiers. | |
b67067f1 | 613 | |
af1f94d0 ST |
614 | config LTO |
615 | def_bool n | |
616 | ||
617 | config ARCH_SUPPORTS_LTO_CLANG | |
618 | bool | |
619 | help | |
620 | An architecture should select this option it supports: | |
621 | - compiling with clang, | |
622 | - compiling inline assembly with clang's integrated assembler, | |
623 | - and linking with either lld or GNU gold w/ LLVMgold. | |
624 | ||
625 | choice | |
626 | prompt "Link-Time Optimization (LTO) (EXPERIMENTAL)" | |
627 | default LTO_NONE | |
628 | help | |
629 | This option turns on Link-Time Optimization (LTO). | |
630 | ||
631 | config LTO_NONE | |
632 | bool "None" | |
633 | ||
634 | config LTO_CLANG | |
635 | bool "Use clang Link Time Optimization (LTO) (EXPERIMENTAL)" | |
636 | depends on ARCH_SUPPORTS_LTO_CLANG | |
9abcee51 | 637 | depends on !FTRACE_MCOUNT_RECORD || HAVE_C_RECORDMCOUNT |
84b5e124 | 638 | depends on !KASAN |
af1f94d0 ST |
639 | select LTO |
640 | select THIN_ARCHIVES | |
641 | select LD_DEAD_CODE_DATA_ELIMINATION | |
642 | help | |
643 | This option enables clang's Link Time Optimization (LTO), which allows | |
644 | the compiler to optimize the kernel globally at link time. If you | |
645 | enable this option, the compiler generates LLVM IR instead of object | |
646 | files, and the actual compilation from IR occurs at the LTO link step, | |
647 | which may take several minutes. | |
648 | ||
649 | If you select this option, you must compile the kernel with clang >= | |
650 | 5.0 (make CC=clang) and GNU gold from binutils >= 2.27, and have the | |
651 | LLVMgold plug-in in LD_LIBRARY_PATH. | |
652 | ||
653 | endchoice | |
654 | ||
d590fd12 ST |
655 | config CFI |
656 | bool | |
657 | ||
658 | config CFI_PERMISSIVE | |
659 | bool "Use CFI in permissive mode" | |
660 | depends on CFI | |
661 | help | |
662 | When selected, Control Flow Integrity (CFI) violations result in a | |
663 | warning instead of a kernel panic. This option is useful for finding | |
664 | CFI violations in drivers during development. | |
665 | ||
666 | config CFI_CLANG | |
667 | bool "Use clang Control Flow Integrity (CFI) (EXPERIMENTAL)" | |
668 | depends on LTO_CLANG | |
669 | depends on KALLSYMS | |
670 | select CFI | |
671 | help | |
672 | This option enables clang Control Flow Integrity (CFI), which adds | |
673 | runtime checking for indirect function calls. | |
674 | ||
675 | config CFI_CLANG_SHADOW | |
676 | bool "Use CFI shadow to speed up cross-module checks" | |
677 | default y | |
678 | depends on CFI_CLANG | |
679 | help | |
680 | If you select this option, the kernel builds a fast look-up table of | |
681 | CFI check functions in loaded modules to reduce overhead. | |
682 | ||
0f60a8ef KC |
683 | config HAVE_ARCH_WITHIN_STACK_FRAMES |
684 | bool | |
685 | help | |
686 | An architecture should select this if it can walk the kernel stack | |
687 | frames to determine if an object is part of either the arguments | |
688 | or local variables (i.e. that it excludes saved return addresses, | |
689 | and similar) by implementing an inline arch_within_stack_frames(), | |
690 | which is used by CONFIG_HARDENED_USERCOPY. | |
691 | ||
91d1aa43 | 692 | config HAVE_CONTEXT_TRACKING |
2b1d5024 FW |
693 | bool |
694 | help | |
91d1aa43 FW |
695 | Provide kernel/user boundaries probes necessary for subsystems |
696 | that need it, such as userspace RCU extended quiescent state. | |
697 | Syscalls need to be wrapped inside user_exit()-user_enter() through | |
698 | the slow path using TIF_NOHZ flag. Exceptions handlers must be | |
699 | wrapped as well. Irqs are already protected inside | |
700 | rcu_irq_enter/rcu_irq_exit() but preemption or signal handling on | |
701 | irq exit still need to be protected. | |
2b1d5024 | 702 | |
b952741c FW |
703 | config HAVE_VIRT_CPU_ACCOUNTING |
704 | bool | |
705 | ||
40565b5a SG |
706 | config ARCH_HAS_SCALED_CPUTIME |
707 | bool | |
708 | ||
554b0004 KH |
709 | config HAVE_VIRT_CPU_ACCOUNTING_GEN |
710 | bool | |
711 | default y if 64BIT | |
712 | help | |
713 | With VIRT_CPU_ACCOUNTING_GEN, cputime_t becomes 64-bit. | |
714 | Before enabling this option, arch code must be audited | |
715 | to ensure there are no races in concurrent read/write of | |
716 | cputime_t. For example, reading/writing 64-bit cputime_t on | |
717 | some 32-bit arches may require multiple accesses, so proper | |
718 | locking is needed to protect against concurrent accesses. | |
719 | ||
720 | ||
fdf9c356 FW |
721 | config HAVE_IRQ_TIME_ACCOUNTING |
722 | bool | |
723 | help | |
724 | Archs need to ensure they use a high enough resolution clock to | |
725 | support irq time accounting and then call enable_sched_clock_irqtime(). | |
726 | ||
15626062 GS |
727 | config HAVE_ARCH_TRANSPARENT_HUGEPAGE |
728 | bool | |
729 | ||
a00cc7d9 MW |
730 | config HAVE_ARCH_TRANSPARENT_HUGEPAGE_PUD |
731 | bool | |
732 | ||
0ddab1d2 TK |
733 | config HAVE_ARCH_HUGE_VMAP |
734 | bool | |
735 | ||
0f8975ec PE |
736 | config HAVE_ARCH_SOFT_DIRTY |
737 | bool | |
738 | ||
786d35d4 DH |
739 | config HAVE_MOD_ARCH_SPECIFIC |
740 | bool | |
741 | help | |
742 | The arch uses struct mod_arch_specific to store data. Many arches | |
743 | just need a simple module loader without arch specific data - those | |
744 | should not enable this. | |
745 | ||
746 | config MODULES_USE_ELF_RELA | |
747 | bool | |
748 | help | |
749 | Modules only use ELF RELA relocations. Modules with ELF REL | |
750 | relocations will give an error. | |
751 | ||
752 | config MODULES_USE_ELF_REL | |
753 | bool | |
754 | help | |
755 | Modules only use ELF REL relocations. Modules with ELF RELA | |
756 | relocations will give an error. | |
757 | ||
b92021b0 RR |
758 | config HAVE_UNDERSCORE_SYMBOL_PREFIX |
759 | bool | |
760 | help | |
761 | Some architectures generate an _ in front of C symbols; things like | |
762 | module loading and assembly files need to know about this. | |
763 | ||
cc1f0274 FW |
764 | config HAVE_IRQ_EXIT_ON_IRQ_STACK |
765 | bool | |
766 | help | |
767 | Architecture doesn't only execute the irq handler on the irq stack | |
768 | but also irq_exit(). This way we can process softirqs on this irq | |
769 | stack instead of switching to a new one when we call __do_softirq() | |
770 | in the end of an hardirq. | |
771 | This spares a stack switch and improves cache usage on softirq | |
772 | processing. | |
773 | ||
235a8f02 KS |
774 | config PGTABLE_LEVELS |
775 | int | |
776 | default 2 | |
777 | ||
2b68f6ca KC |
778 | config ARCH_HAS_ELF_RANDOMIZE |
779 | bool | |
780 | help | |
781 | An architecture supports choosing randomized locations for | |
782 | stack, mmap, brk, and ET_DYN. Defined functions: | |
783 | - arch_mmap_rnd() | |
204db6ed | 784 | - arch_randomize_brk() |
2b68f6ca | 785 | |
d07e2259 DC |
786 | config HAVE_ARCH_MMAP_RND_BITS |
787 | bool | |
788 | help | |
789 | An arch should select this symbol if it supports setting a variable | |
790 | number of bits for use in establishing the base address for mmap | |
791 | allocations, has MMU enabled and provides values for both: | |
792 | - ARCH_MMAP_RND_BITS_MIN | |
793 | - ARCH_MMAP_RND_BITS_MAX | |
794 | ||
5f56a5df JS |
795 | config HAVE_EXIT_THREAD |
796 | bool | |
797 | help | |
798 | An architecture implements exit_thread. | |
799 | ||
d07e2259 DC |
800 | config ARCH_MMAP_RND_BITS_MIN |
801 | int | |
802 | ||
803 | config ARCH_MMAP_RND_BITS_MAX | |
804 | int | |
805 | ||
806 | config ARCH_MMAP_RND_BITS_DEFAULT | |
807 | int | |
808 | ||
809 | config ARCH_MMAP_RND_BITS | |
810 | int "Number of bits to use for ASLR of mmap base address" if EXPERT | |
811 | range ARCH_MMAP_RND_BITS_MIN ARCH_MMAP_RND_BITS_MAX | |
812 | default ARCH_MMAP_RND_BITS_DEFAULT if ARCH_MMAP_RND_BITS_DEFAULT | |
813 | default ARCH_MMAP_RND_BITS_MIN | |
814 | depends on HAVE_ARCH_MMAP_RND_BITS | |
815 | help | |
816 | This value can be used to select the number of bits to use to | |
817 | determine the random offset to the base address of vma regions | |
818 | resulting from mmap allocations. This value will be bounded | |
819 | by the architecture's minimum and maximum supported values. | |
820 | ||
821 | This value can be changed after boot using the | |
822 | /proc/sys/vm/mmap_rnd_bits tunable | |
823 | ||
824 | config HAVE_ARCH_MMAP_RND_COMPAT_BITS | |
825 | bool | |
826 | help | |
827 | An arch should select this symbol if it supports running applications | |
828 | in compatibility mode, supports setting a variable number of bits for | |
829 | use in establishing the base address for mmap allocations, has MMU | |
830 | enabled and provides values for both: | |
831 | - ARCH_MMAP_RND_COMPAT_BITS_MIN | |
832 | - ARCH_MMAP_RND_COMPAT_BITS_MAX | |
833 | ||
834 | config ARCH_MMAP_RND_COMPAT_BITS_MIN | |
835 | int | |
836 | ||
837 | config ARCH_MMAP_RND_COMPAT_BITS_MAX | |
838 | int | |
839 | ||
840 | config ARCH_MMAP_RND_COMPAT_BITS_DEFAULT | |
841 | int | |
842 | ||
843 | config ARCH_MMAP_RND_COMPAT_BITS | |
844 | int "Number of bits to use for ASLR of mmap base address for compatible applications" if EXPERT | |
845 | range ARCH_MMAP_RND_COMPAT_BITS_MIN ARCH_MMAP_RND_COMPAT_BITS_MAX | |
846 | default ARCH_MMAP_RND_COMPAT_BITS_DEFAULT if ARCH_MMAP_RND_COMPAT_BITS_DEFAULT | |
847 | default ARCH_MMAP_RND_COMPAT_BITS_MIN | |
848 | depends on HAVE_ARCH_MMAP_RND_COMPAT_BITS | |
849 | help | |
850 | This value can be used to select the number of bits to use to | |
851 | determine the random offset to the base address of vma regions | |
852 | resulting from mmap allocations for compatible applications This | |
853 | value will be bounded by the architecture's minimum and maximum | |
854 | supported values. | |
855 | ||
856 | This value can be changed after boot using the | |
857 | /proc/sys/vm/mmap_rnd_compat_bits tunable | |
858 | ||
1b028f78 DS |
859 | config HAVE_ARCH_COMPAT_MMAP_BASES |
860 | bool | |
861 | help | |
862 | This allows 64bit applications to invoke 32-bit mmap() syscall | |
863 | and vice-versa 32-bit applications to call 64-bit mmap(). | |
864 | Required for applications doing different bitness syscalls. | |
865 | ||
3033f14a JT |
866 | config HAVE_COPY_THREAD_TLS |
867 | bool | |
868 | help | |
869 | Architecture provides copy_thread_tls to accept tls argument via | |
870 | normal C parameter passing, rather than extracting the syscall | |
871 | argument from pt_regs. | |
872 | ||
b9ab5ebb JP |
873 | config HAVE_STACK_VALIDATION |
874 | bool | |
875 | help | |
876 | Architecture supports the 'objtool check' host tool command, which | |
877 | performs compile-time stack metadata validation. | |
878 | ||
af085d90 JP |
879 | config HAVE_RELIABLE_STACKTRACE |
880 | bool | |
881 | help | |
882 | Architecture has a save_stack_trace_tsk_reliable() function which | |
883 | only returns a stack trace if it can guarantee the trace is reliable. | |
884 | ||
468a9428 GS |
885 | config HAVE_ARCH_HASH |
886 | bool | |
887 | default n | |
888 | help | |
889 | If this is set, the architecture provides an <asm/hash.h> | |
890 | file which provides platform-specific implementations of some | |
891 | functions in <linux/hash.h> or fs/namei.c. | |
892 | ||
3a495511 WBG |
893 | config ISA_BUS_API |
894 | def_bool ISA | |
895 | ||
d2125043 AV |
896 | # |
897 | # ABI hall of shame | |
898 | # | |
899 | config CLONE_BACKWARDS | |
900 | bool | |
901 | help | |
902 | Architecture has tls passed as the 4th argument of clone(2), | |
903 | not the 5th one. | |
904 | ||
905 | config CLONE_BACKWARDS2 | |
906 | bool | |
907 | help | |
908 | Architecture has the first two arguments of clone(2) swapped. | |
909 | ||
dfa9771a MS |
910 | config CLONE_BACKWARDS3 |
911 | bool | |
912 | help | |
913 | Architecture has tls passed as the 3rd argument of clone(2), | |
914 | not the 5th one. | |
915 | ||
eaca6eae AV |
916 | config ODD_RT_SIGACTION |
917 | bool | |
918 | help | |
919 | Architecture has unusual rt_sigaction(2) arguments | |
920 | ||
0a0e8cdf AV |
921 | config OLD_SIGSUSPEND |
922 | bool | |
923 | help | |
924 | Architecture has old sigsuspend(2) syscall, of one-argument variety | |
925 | ||
926 | config OLD_SIGSUSPEND3 | |
927 | bool | |
928 | help | |
929 | Even weirder antique ABI - three-argument sigsuspend(2) | |
930 | ||
495dfbf7 AV |
931 | config OLD_SIGACTION |
932 | bool | |
933 | help | |
934 | Architecture has old sigaction(2) syscall. Nope, not the same | |
935 | as OLD_SIGSUSPEND | OLD_SIGSUSPEND3 - alpha has sigsuspend(2), | |
936 | but fairly different variant of sigaction(2), thanks to OSF/1 | |
937 | compatibility... | |
938 | ||
939 | config COMPAT_OLD_SIGACTION | |
940 | bool | |
941 | ||
0d4a619b CH |
942 | config ARCH_NO_COHERENT_DMA_MMAP |
943 | bool | |
944 | ||
fff7fb0b ZZ |
945 | config CPU_NO_EFFICIENT_FFS |
946 | def_bool n | |
947 | ||
ba14a194 AL |
948 | config HAVE_ARCH_VMAP_STACK |
949 | def_bool n | |
950 | help | |
951 | An arch should select this symbol if it can support kernel stacks | |
952 | in vmalloc space. This means: | |
953 | ||
954 | - vmalloc space must be large enough to hold many kernel stacks. | |
955 | This may rule out many 32-bit architectures. | |
956 | ||
957 | - Stacks in vmalloc space need to work reliably. For example, if | |
958 | vmap page tables are created on demand, either this mechanism | |
959 | needs to work while the stack points to a virtual address with | |
960 | unpopulated page tables or arch code (switch_to() and switch_mm(), | |
961 | most likely) needs to ensure that the stack's page table entries | |
962 | are populated before running on a possibly unpopulated stack. | |
963 | ||
964 | - If the stack overflows into a guard page, something reasonable | |
965 | should happen. The definition of "reasonable" is flexible, but | |
966 | instantly rebooting without logging anything would be unfriendly. | |
967 | ||
968 | config VMAP_STACK | |
969 | default y | |
970 | bool "Use a virtually-mapped stack" | |
971 | depends on HAVE_ARCH_VMAP_STACK && !KASAN | |
972 | ---help--- | |
973 | Enable this if you want the use virtually-mapped kernel stacks | |
974 | with guard pages. This causes kernel stack overflows to be | |
975 | caught immediately rather than causing difficult-to-diagnose | |
976 | corruption. | |
977 | ||
978 | This is presently incompatible with KASAN because KASAN expects | |
979 | the stack to map directly to the KASAN shadow map using a formula | |
980 | that is incorrect if the stack is in vmalloc space. | |
981 | ||
ad21fc4f LA |
982 | config ARCH_OPTIONAL_KERNEL_RWX |
983 | def_bool n | |
984 | ||
985 | config ARCH_OPTIONAL_KERNEL_RWX_DEFAULT | |
986 | def_bool n | |
987 | ||
988 | config ARCH_HAS_STRICT_KERNEL_RWX | |
989 | def_bool n | |
990 | ||
0f5bf6d0 | 991 | config STRICT_KERNEL_RWX |
ad21fc4f LA |
992 | bool "Make kernel text and rodata read-only" if ARCH_OPTIONAL_KERNEL_RWX |
993 | depends on ARCH_HAS_STRICT_KERNEL_RWX | |
994 | default !ARCH_OPTIONAL_KERNEL_RWX || ARCH_OPTIONAL_KERNEL_RWX_DEFAULT | |
995 | help | |
996 | If this is set, kernel text and rodata memory will be made read-only, | |
997 | and non-text memory will be made non-executable. This provides | |
998 | protection against certain security exploits (e.g. executing the heap | |
999 | or modifying text) | |
1000 | ||
1001 | These features are considered standard security practice these days. | |
1002 | You should say Y here in almost all cases. | |
1003 | ||
1004 | config ARCH_HAS_STRICT_MODULE_RWX | |
1005 | def_bool n | |
1006 | ||
0f5bf6d0 | 1007 | config STRICT_MODULE_RWX |
ad21fc4f LA |
1008 | bool "Set loadable kernel module data as NX and text as RO" if ARCH_OPTIONAL_KERNEL_RWX |
1009 | depends on ARCH_HAS_STRICT_MODULE_RWX && MODULES | |
1010 | default !ARCH_OPTIONAL_KERNEL_RWX || ARCH_OPTIONAL_KERNEL_RWX_DEFAULT | |
1011 | help | |
1012 | If this is set, module text and rodata memory will be made read-only, | |
1013 | and non-text memory will be made non-executable. This provides | |
1014 | protection against certain security exploits (e.g. writing to text) | |
1015 | ||
7a46ec0e KC |
1016 | config ARCH_HAS_REFCOUNT |
1017 | bool | |
1018 | help | |
1019 | An architecture selects this when it has implemented refcount_t | |
1020 | using open coded assembly primitives that provide an optimized | |
1021 | refcount_t implementation, possibly at the expense of some full | |
1022 | refcount state checks of CONFIG_REFCOUNT_FULL=y. | |
1023 | ||
1024 | The refcount overflow check behavior, however, must be retained. | |
1025 | Catching overflows is the primary security concern for protecting | |
1026 | against bugs in reference counts. | |
1027 | ||
fd25d19f KC |
1028 | config REFCOUNT_FULL |
1029 | bool "Perform full reference count validation at the expense of speed" | |
1030 | help | |
1031 | Enabling this switches the refcounting infrastructure from a fast | |
1032 | unchecked atomic_t implementation to a fully state checked | |
1033 | implementation, which can be (slightly) slower but provides protections | |
1034 | against various use-after-free conditions that can be used in | |
1035 | security flaw exploits. | |
1036 | ||
3c3bec81 PB |
1037 | config HAVE_ARCH_COMPILER_H |
1038 | bool | |
1039 | help | |
1040 | An architecture can select this if it provides an | |
1041 | asm/compiler.h header that should be included after | |
1042 | linux/compiler-*.h in order to override macro definitions that those | |
1043 | headers generally provide. | |
1044 | ||
2521f2c2 | 1045 | source "kernel/gcov/Kconfig" |