Commit | Line | Data |
---|---|---|
fb32e03f MD |
1 | # |
2 | # General architecture dependent options | |
3 | # | |
125e5645 | 4 | |
692f66f2 HB |
5 | config CRASH_CORE |
6 | bool | |
7 | ||
2965faa5 | 8 | config KEXEC_CORE |
692f66f2 | 9 | select CRASH_CORE |
2965faa5 DY |
10 | bool |
11 | ||
467d2782 TJB |
12 | config HAVE_IMA_KEXEC |
13 | bool | |
14 | ||
125e5645 | 15 | config OPROFILE |
b309a294 | 16 | tristate "OProfile system profiling" |
125e5645 MD |
17 | depends on PROFILING |
18 | depends on HAVE_OPROFILE | |
d69d59f4 | 19 | select RING_BUFFER |
9a5963eb | 20 | select RING_BUFFER_ALLOW_SWAP |
125e5645 MD |
21 | help |
22 | OProfile is a profiling system capable of profiling the | |
23 | whole system, include the kernel, kernel modules, libraries, | |
24 | and applications. | |
25 | ||
26 | If unsure, say N. | |
27 | ||
4d4036e0 JY |
28 | config OPROFILE_EVENT_MULTIPLEX |
29 | bool "OProfile multiplexing support (EXPERIMENTAL)" | |
30 | default n | |
31 | depends on OPROFILE && X86 | |
32 | help | |
33 | The number of hardware counters is limited. The multiplexing | |
34 | feature enables OProfile to gather more events than counters | |
35 | are provided by the hardware. This is realized by switching | |
9332ef9d | 36 | between events at a user specified time interval. |
4d4036e0 JY |
37 | |
38 | If unsure, say N. | |
39 | ||
125e5645 | 40 | config HAVE_OPROFILE |
9ba16087 | 41 | bool |
125e5645 | 42 | |
dcfce4a0 RR |
43 | config OPROFILE_NMI_TIMER |
44 | def_bool y | |
af9feebe | 45 | depends on PERF_EVENTS && HAVE_PERF_EVENTS_NMI && !PPC64 |
dcfce4a0 | 46 | |
125e5645 MD |
47 | config KPROBES |
48 | bool "Kprobes" | |
05ed160e | 49 | depends on MODULES |
125e5645 | 50 | depends on HAVE_KPROBES |
05ed160e | 51 | select KALLSYMS |
125e5645 MD |
52 | help |
53 | Kprobes allows you to trap at almost any kernel address and | |
54 | execute a callback function. register_kprobe() establishes | |
55 | a probepoint and specifies the callback. Kprobes is useful | |
56 | for kernel debugging, non-intrusive instrumentation and testing. | |
57 | If in doubt, say "N". | |
58 | ||
45f81b1c | 59 | config JUMP_LABEL |
c5905afb | 60 | bool "Optimize very unlikely/likely branches" |
45f81b1c SR |
61 | depends on HAVE_ARCH_JUMP_LABEL |
62 | help | |
c5905afb IM |
63 | This option enables a transparent branch optimization that |
64 | makes certain almost-always-true or almost-always-false branch | |
65 | conditions even cheaper to execute within the kernel. | |
66 | ||
67 | Certain performance-sensitive kernel code, such as trace points, | |
68 | scheduler functionality, networking code and KVM have such | |
69 | branches and include support for this optimization technique. | |
70 | ||
45f81b1c | 71 | If it is detected that the compiler has support for "asm goto", |
c5905afb IM |
72 | the kernel will compile such branches with just a nop |
73 | instruction. When the condition flag is toggled to true, the | |
74 | nop will be converted to a jump instruction to execute the | |
75 | conditional block of instructions. | |
76 | ||
77 | This technique lowers overhead and stress on the branch prediction | |
78 | of the processor and generally makes the kernel faster. The update | |
79 | of the condition is slower, but those are always very rare. | |
45f81b1c | 80 | |
c5905afb IM |
81 | ( On 32-bit x86, the necessary options added to the compiler |
82 | flags may increase the size of the kernel slightly. ) | |
45f81b1c | 83 | |
1987c947 PZ |
84 | config STATIC_KEYS_SELFTEST |
85 | bool "Static key selftest" | |
86 | depends on JUMP_LABEL | |
87 | help | |
88 | Boot time self-test of the branch patching code. | |
89 | ||
afd66255 | 90 | config OPTPROBES |
5cc718b9 MH |
91 | def_bool y |
92 | depends on KPROBES && HAVE_OPTPROBES | |
afd66255 | 93 | depends on !PREEMPT |
afd66255 | 94 | |
e7dbfe34 MH |
95 | config KPROBES_ON_FTRACE |
96 | def_bool y | |
97 | depends on KPROBES && HAVE_KPROBES_ON_FTRACE | |
98 | depends on DYNAMIC_FTRACE_WITH_REGS | |
99 | help | |
100 | If function tracer is enabled and the arch supports full | |
101 | passing of pt_regs to function tracing, then kprobes can | |
102 | optimize on top of function tracing. | |
103 | ||
2b144498 | 104 | config UPROBES |
09294e31 | 105 | def_bool n |
e8f4aa60 | 106 | depends on ARCH_SUPPORTS_UPROBES |
2b144498 | 107 | help |
7b2d81d4 IM |
108 | Uprobes is the user-space counterpart to kprobes: they |
109 | enable instrumentation applications (such as 'perf probe') | |
110 | to establish unintrusive probes in user-space binaries and | |
111 | libraries, by executing handler functions when the probes | |
112 | are hit by user-space applications. | |
113 | ||
114 | ( These probes come in the form of single-byte breakpoints, | |
115 | managed by the kernel and kept transparent to the probed | |
116 | application. ) | |
2b144498 | 117 | |
c19fa94a JH |
118 | config HAVE_64BIT_ALIGNED_ACCESS |
119 | def_bool 64BIT && !HAVE_EFFICIENT_UNALIGNED_ACCESS | |
120 | help | |
121 | Some architectures require 64 bit accesses to be 64 bit | |
122 | aligned, which also requires structs containing 64 bit values | |
123 | to be 64 bit aligned too. This includes some 32 bit | |
124 | architectures which can do 64 bit accesses, as well as 64 bit | |
125 | architectures without unaligned access. | |
126 | ||
127 | This symbol should be selected by an architecture if 64 bit | |
128 | accesses are required to be 64 bit aligned in this way even | |
129 | though it is not a 64 bit architecture. | |
130 | ||
131 | See Documentation/unaligned-memory-access.txt for more | |
132 | information on the topic of unaligned memory accesses. | |
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 DW |
153 | config ARCH_USE_BUILTIN_BSWAP |
154 | bool | |
155 | help | |
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 | ||
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 | ||
d2852a22 DB |
226 | # Select if arch has all set_memory_ro/rw/x/nx() functions in asm/cacheflush.h |
227 | config ARCH_HAS_SET_MEMORY | |
228 | bool | |
229 | ||
a6359d1e TG |
230 | # Select if arch init_task initializer is different to init/init_task.c |
231 | config ARCH_INIT_TASK | |
a4a2eb49 TG |
232 | bool |
233 | ||
f5e10287 TG |
234 | # Select if arch has its private alloc_task_struct() function |
235 | config ARCH_TASK_STRUCT_ALLOCATOR | |
236 | bool | |
237 | ||
b235beea LT |
238 | # Select if arch has its private alloc_thread_stack() function |
239 | config ARCH_THREAD_STACK_ALLOCATOR | |
f5e10287 TG |
240 | bool |
241 | ||
5aaeb5c0 IM |
242 | # Select if arch wants to size task_struct dynamically via arch_task_struct_size: |
243 | config ARCH_WANTS_DYNAMIC_TASK_STRUCT | |
244 | bool | |
245 | ||
f850c30c HC |
246 | config HAVE_REGS_AND_STACK_ACCESS_API |
247 | bool | |
e01292b1 HC |
248 | help |
249 | This symbol should be selected by an architecure if it supports | |
250 | the API needed to access registers and stack entries from pt_regs, | |
251 | declared in asm/ptrace.h | |
252 | For example the kprobes-based event tracer needs this API. | |
f850c30c | 253 | |
9483a578 | 254 | config HAVE_CLK |
9ba16087 | 255 | bool |
9483a578 DB |
256 | help |
257 | The <linux/clk.h> calls support software clock gating and | |
258 | thus are a key power management tool on many systems. | |
259 | ||
5ee00bd4 JR |
260 | config HAVE_DMA_API_DEBUG |
261 | bool | |
36cd3c9f | 262 | |
62a038d3 P |
263 | config HAVE_HW_BREAKPOINT |
264 | bool | |
99e8c5a3 | 265 | depends on PERF_EVENTS |
62a038d3 | 266 | |
0102752e FW |
267 | config HAVE_MIXED_BREAKPOINTS_REGS |
268 | bool | |
269 | depends on HAVE_HW_BREAKPOINT | |
270 | help | |
271 | Depending on the arch implementation of hardware breakpoints, | |
272 | some of them have separate registers for data and instruction | |
273 | breakpoints addresses, others have mixed registers to store | |
274 | them but define the access type in a control register. | |
275 | Select this option if your arch implements breakpoints under the | |
276 | latter fashion. | |
277 | ||
7c68af6e AK |
278 | config HAVE_USER_RETURN_NOTIFIER |
279 | bool | |
a1922ed6 | 280 | |
c01d4323 FW |
281 | config HAVE_PERF_EVENTS_NMI |
282 | bool | |
23637d47 FW |
283 | help |
284 | System hardware can generate an NMI using the perf event | |
285 | subsystem. Also has support for calculating CPU cycle events | |
286 | to determine how many clock cycles in a given period. | |
c01d4323 | 287 | |
05a4a952 NP |
288 | config HAVE_HARDLOCKUP_DETECTOR_PERF |
289 | bool | |
290 | depends on HAVE_PERF_EVENTS_NMI | |
291 | help | |
292 | The arch chooses to use the generic perf-NMI-based hardlockup | |
293 | detector. Must define HAVE_PERF_EVENTS_NMI. | |
294 | ||
295 | config HAVE_NMI_WATCHDOG | |
296 | depends on HAVE_NMI | |
297 | bool | |
298 | help | |
299 | The arch provides a low level NMI watchdog. It provides | |
300 | asm/nmi.h, and defines its own arch_touch_nmi_watchdog(). | |
301 | ||
302 | config HAVE_HARDLOCKUP_DETECTOR_ARCH | |
303 | bool | |
304 | select HAVE_NMI_WATCHDOG | |
305 | help | |
306 | The arch chooses to provide its own hardlockup detector, which is | |
307 | a superset of the HAVE_NMI_WATCHDOG. It also conforms to config | |
308 | interfaces and parameters provided by hardlockup detector subsystem. | |
309 | ||
c5e63197 JO |
310 | config HAVE_PERF_REGS |
311 | bool | |
312 | help | |
313 | Support selective register dumps for perf events. This includes | |
314 | bit-mapping of each registers and a unique architecture id. | |
315 | ||
c5ebcedb JO |
316 | config HAVE_PERF_USER_STACK_DUMP |
317 | bool | |
318 | help | |
319 | Support user stack dumps for perf event samples. This needs | |
320 | access to the user stack pointer which is not unified across | |
321 | architectures. | |
322 | ||
bf5438fc JB |
323 | config HAVE_ARCH_JUMP_LABEL |
324 | bool | |
325 | ||
26723911 PZ |
326 | config HAVE_RCU_TABLE_FREE |
327 | bool | |
328 | ||
df013ffb HY |
329 | config ARCH_HAVE_NMI_SAFE_CMPXCHG |
330 | bool | |
331 | ||
43570fd2 HC |
332 | config HAVE_ALIGNED_STRUCT_PAGE |
333 | bool | |
334 | help | |
335 | This makes sure that struct pages are double word aligned and that | |
336 | e.g. the SLUB allocator can perform double word atomic operations | |
337 | on a struct page for better performance. However selecting this | |
338 | might increase the size of a struct page by a word. | |
339 | ||
4156153c HC |
340 | config HAVE_CMPXCHG_LOCAL |
341 | bool | |
342 | ||
2565409f HC |
343 | config HAVE_CMPXCHG_DOUBLE |
344 | bool | |
345 | ||
77e58496 PM |
346 | config ARCH_WEAK_RELEASE_ACQUIRE |
347 | bool | |
348 | ||
c1d7e01d WD |
349 | config ARCH_WANT_IPC_PARSE_VERSION |
350 | bool | |
351 | ||
352 | config ARCH_WANT_COMPAT_IPC_PARSE_VERSION | |
353 | bool | |
354 | ||
48b25c43 | 355 | config ARCH_WANT_OLD_COMPAT_IPC |
c1d7e01d | 356 | select ARCH_WANT_COMPAT_IPC_PARSE_VERSION |
48b25c43 CM |
357 | bool |
358 | ||
e2cfabdf WD |
359 | config HAVE_ARCH_SECCOMP_FILTER |
360 | bool | |
361 | help | |
fb0fadf9 | 362 | An arch should select this symbol if it provides all of these things: |
bb6ea430 WD |
363 | - syscall_get_arch() |
364 | - syscall_get_arguments() | |
365 | - syscall_rollback() | |
366 | - syscall_set_return_value() | |
fb0fadf9 WD |
367 | - SIGSYS siginfo_t support |
368 | - secure_computing is called from a ptrace_event()-safe context | |
369 | - secure_computing return value is checked and a return value of -1 | |
370 | results in the system call being skipped immediately. | |
48dc92b9 | 371 | - seccomp syscall wired up |
e2cfabdf WD |
372 | |
373 | config SECCOMP_FILTER | |
374 | def_bool y | |
375 | depends on HAVE_ARCH_SECCOMP_FILTER && SECCOMP && NET | |
376 | help | |
377 | Enable tasks to build secure computing environments defined | |
378 | in terms of Berkeley Packet Filter programs which implement | |
379 | task-defined system call filtering polices. | |
380 | ||
381 | See Documentation/prctl/seccomp_filter.txt for details. | |
382 | ||
6b90bd4b ER |
383 | config HAVE_GCC_PLUGINS |
384 | bool | |
385 | help | |
386 | An arch should select this symbol if it supports building with | |
387 | GCC plugins. | |
388 | ||
389 | menuconfig GCC_PLUGINS | |
390 | bool "GCC plugins" | |
391 | depends on HAVE_GCC_PLUGINS | |
a519167e | 392 | depends on !COMPILE_TEST |
6b90bd4b ER |
393 | help |
394 | GCC plugins are loadable modules that provide extra features to the | |
395 | compiler. They are useful for runtime instrumentation and static analysis. | |
396 | ||
397 | See Documentation/gcc-plugins.txt for details. | |
398 | ||
0dae776c | 399 | config GCC_PLUGIN_CYC_COMPLEXITY |
215e2aa6 | 400 | bool "Compute the cyclomatic complexity of a function" if EXPERT |
0dae776c | 401 | depends on GCC_PLUGINS |
215e2aa6 | 402 | depends on !COMPILE_TEST |
0dae776c ER |
403 | help |
404 | The complexity M of a function's control flow graph is defined as: | |
405 | M = E - N + 2P | |
406 | where | |
407 | ||
408 | E = the number of edges | |
409 | N = the number of nodes | |
410 | P = the number of connected components (exit nodes). | |
411 | ||
215e2aa6 KC |
412 | Enabling this plugin reports the complexity to stderr during the |
413 | build. It mainly serves as a simple example of how to create a | |
414 | gcc plugin for the kernel. | |
415 | ||
543c37cb ER |
416 | config GCC_PLUGIN_SANCOV |
417 | bool | |
418 | depends on GCC_PLUGINS | |
419 | help | |
420 | This plugin inserts a __sanitizer_cov_trace_pc() call at the start of | |
421 | basic blocks. It supports all gcc versions with plugin support (from | |
422 | gcc-4.5 on). It is based on the commit "Add fuzzing coverage support" | |
423 | by Dmitry Vyukov <dvyukov@google.com>. | |
424 | ||
38addce8 ER |
425 | config GCC_PLUGIN_LATENT_ENTROPY |
426 | bool "Generate some entropy during boot and runtime" | |
427 | depends on GCC_PLUGINS | |
428 | help | |
429 | By saying Y here the kernel will instrument some kernel code to | |
430 | extract some entropy from both original and artificially created | |
431 | program state. This will help especially embedded systems where | |
432 | there is little 'natural' source of entropy normally. The cost | |
433 | is some slowdown of the boot process (about 0.5%) and fork and | |
434 | irq processing. | |
435 | ||
436 | Note that entropy extracted this way is not cryptographically | |
437 | secure! | |
438 | ||
439 | This plugin was ported from grsecurity/PaX. More information at: | |
440 | * https://grsecurity.net/ | |
441 | * https://pax.grsecurity.net/ | |
442 | ||
c61f13ea KC |
443 | config GCC_PLUGIN_STRUCTLEAK |
444 | bool "Force initialization of variables containing userspace addresses" | |
445 | depends on GCC_PLUGINS | |
446 | help | |
f136e090 | 447 | This plugin zero-initializes any structures containing a |
c61f13ea KC |
448 | __user attribute. This can prevent some classes of information |
449 | exposures. | |
450 | ||
451 | This plugin was ported from grsecurity/PaX. More information at: | |
452 | * https://grsecurity.net/ | |
453 | * https://pax.grsecurity.net/ | |
454 | ||
455 | config GCC_PLUGIN_STRUCTLEAK_VERBOSE | |
456 | bool "Report forcefully initialized variables" | |
457 | depends on GCC_PLUGIN_STRUCTLEAK | |
458 | depends on !COMPILE_TEST | |
459 | help | |
460 | This option will cause a warning to be printed each time the | |
461 | structleak plugin finds a variable it thinks needs to be | |
462 | initialized. Since not all existing initializers are detected | |
463 | by the plugin, this can produce false positive warnings. | |
464 | ||
313dd1b6 KC |
465 | config GCC_PLUGIN_RANDSTRUCT |
466 | bool "Randomize layout of sensitive kernel structures" | |
467 | depends on GCC_PLUGINS | |
468 | select MODVERSIONS if MODULES | |
469 | help | |
470 | If you say Y here, the layouts of structures explicitly | |
471 | marked by __randomize_layout will be randomized at | |
472 | compile-time. This can introduce the requirement of an | |
473 | additional information exposure vulnerability for exploits | |
474 | targeting these structure types. | |
475 | ||
476 | Enabling this feature will introduce some performance impact, | |
477 | slightly increase memory usage, and prevent the use of forensic | |
478 | tools like Volatility against the system (unless the kernel | |
479 | source tree isn't cleaned after kernel installation). | |
480 | ||
481 | The seed used for compilation is located at | |
482 | scripts/gcc-plgins/randomize_layout_seed.h. It remains after | |
483 | a make clean to allow for external modules to be compiled with | |
484 | the existing seed and will be removed by a make mrproper or | |
485 | make distclean. | |
486 | ||
487 | Note that the implementation requires gcc 4.7 or newer. | |
488 | ||
489 | This plugin was ported from grsecurity/PaX. More information at: | |
490 | * https://grsecurity.net/ | |
491 | * https://pax.grsecurity.net/ | |
492 | ||
493 | config GCC_PLUGIN_RANDSTRUCT_PERFORMANCE | |
494 | bool "Use cacheline-aware structure randomization" | |
495 | depends on GCC_PLUGIN_RANDSTRUCT | |
496 | depends on !COMPILE_TEST | |
497 | help | |
498 | If you say Y here, the RANDSTRUCT randomization will make a | |
499 | best effort at restricting randomization to cacheline-sized | |
500 | groups of elements. It will further not randomize bitfields | |
501 | in structures. This reduces the performance hit of RANDSTRUCT | |
502 | at the cost of weakened randomization. | |
503 | ||
19952a92 KC |
504 | config HAVE_CC_STACKPROTECTOR |
505 | bool | |
506 | help | |
507 | An arch should select this symbol if: | |
508 | - its compiler supports the -fstack-protector option | |
509 | - it has implemented a stack canary (e.g. __stack_chk_guard) | |
510 | ||
511 | config CC_STACKPROTECTOR | |
8779657d KC |
512 | def_bool n |
513 | help | |
514 | Set when a stack-protector mode is enabled, so that the build | |
515 | can enable kernel-side support for the GCC feature. | |
516 | ||
517 | choice | |
518 | prompt "Stack Protector buffer overflow detection" | |
19952a92 | 519 | depends on HAVE_CC_STACKPROTECTOR |
8779657d | 520 | default CC_STACKPROTECTOR_NONE |
19952a92 | 521 | help |
8779657d | 522 | This option turns on the "stack-protector" GCC feature. This |
19952a92 KC |
523 | feature puts, at the beginning of functions, a canary value on |
524 | the stack just before the return address, and validates | |
525 | the value just before actually returning. Stack based buffer | |
526 | overflows (that need to overwrite this return address) now also | |
527 | overwrite the canary, which gets detected and the attack is then | |
528 | neutralized via a kernel panic. | |
529 | ||
8779657d KC |
530 | config CC_STACKPROTECTOR_NONE |
531 | bool "None" | |
532 | help | |
533 | Disable "stack-protector" GCC feature. | |
534 | ||
535 | config CC_STACKPROTECTOR_REGULAR | |
536 | bool "Regular" | |
537 | select CC_STACKPROTECTOR | |
538 | help | |
539 | Functions will have the stack-protector canary logic added if they | |
540 | have an 8-byte or larger character array on the stack. | |
541 | ||
19952a92 | 542 | This feature requires gcc version 4.2 or above, or a distribution |
8779657d KC |
543 | gcc with the feature backported ("-fstack-protector"). |
544 | ||
545 | On an x86 "defconfig" build, this feature adds canary checks to | |
546 | about 3% of all kernel functions, which increases kernel code size | |
547 | by about 0.3%. | |
548 | ||
549 | config CC_STACKPROTECTOR_STRONG | |
550 | bool "Strong" | |
551 | select CC_STACKPROTECTOR | |
552 | help | |
553 | Functions will have the stack-protector canary logic added in any | |
554 | of the following conditions: | |
555 | ||
556 | - local variable's address used as part of the right hand side of an | |
557 | assignment or function argument | |
558 | - local variable is an array (or union containing an array), | |
559 | regardless of array type or length | |
560 | - uses register local variables | |
561 | ||
562 | This feature requires gcc version 4.9 or above, or a distribution | |
563 | gcc with the feature backported ("-fstack-protector-strong"). | |
564 | ||
565 | On an x86 "defconfig" build, this feature adds canary checks to | |
566 | about 20% of all kernel functions, which increases the kernel code | |
567 | size by about 2%. | |
568 | ||
569 | endchoice | |
19952a92 | 570 | |
a5967db9 | 571 | config THIN_ARCHIVES |
799c4341 | 572 | def_bool y |
a5967db9 SR |
573 | help |
574 | Select this if the architecture wants to use thin archives | |
575 | instead of ld -r to create the built-in.o files. | |
576 | ||
b67067f1 NP |
577 | config LD_DEAD_CODE_DATA_ELIMINATION |
578 | bool | |
579 | help | |
580 | Select this if the architecture wants to do dead code and | |
581 | data elimination with the linker by compiling with | |
582 | -ffunction-sections -fdata-sections and linking with | |
583 | --gc-sections. | |
584 | ||
585 | This requires that the arch annotates or otherwise protects | |
586 | its external entry points from being discarded. Linker scripts | |
587 | must also merge .text.*, .data.*, and .bss.* correctly into | |
0f4c4af0 NP |
588 | output sections. Care must be taken not to pull in unrelated |
589 | sections (e.g., '.text.init'). Typically '.' in section names | |
590 | is used to distinguish them from label names / C identifiers. | |
b67067f1 | 591 | |
0f60a8ef KC |
592 | config HAVE_ARCH_WITHIN_STACK_FRAMES |
593 | bool | |
594 | help | |
595 | An architecture should select this if it can walk the kernel stack | |
596 | frames to determine if an object is part of either the arguments | |
597 | or local variables (i.e. that it excludes saved return addresses, | |
598 | and similar) by implementing an inline arch_within_stack_frames(), | |
599 | which is used by CONFIG_HARDENED_USERCOPY. | |
600 | ||
91d1aa43 | 601 | config HAVE_CONTEXT_TRACKING |
2b1d5024 FW |
602 | bool |
603 | help | |
91d1aa43 FW |
604 | Provide kernel/user boundaries probes necessary for subsystems |
605 | that need it, such as userspace RCU extended quiescent state. | |
606 | Syscalls need to be wrapped inside user_exit()-user_enter() through | |
607 | the slow path using TIF_NOHZ flag. Exceptions handlers must be | |
608 | wrapped as well. Irqs are already protected inside | |
609 | rcu_irq_enter/rcu_irq_exit() but preemption or signal handling on | |
610 | irq exit still need to be protected. | |
2b1d5024 | 611 | |
b952741c FW |
612 | config HAVE_VIRT_CPU_ACCOUNTING |
613 | bool | |
614 | ||
40565b5a SG |
615 | config ARCH_HAS_SCALED_CPUTIME |
616 | bool | |
617 | ||
554b0004 KH |
618 | config HAVE_VIRT_CPU_ACCOUNTING_GEN |
619 | bool | |
620 | default y if 64BIT | |
621 | help | |
622 | With VIRT_CPU_ACCOUNTING_GEN, cputime_t becomes 64-bit. | |
623 | Before enabling this option, arch code must be audited | |
624 | to ensure there are no races in concurrent read/write of | |
625 | cputime_t. For example, reading/writing 64-bit cputime_t on | |
626 | some 32-bit arches may require multiple accesses, so proper | |
627 | locking is needed to protect against concurrent accesses. | |
628 | ||
629 | ||
fdf9c356 FW |
630 | config HAVE_IRQ_TIME_ACCOUNTING |
631 | bool | |
632 | help | |
633 | Archs need to ensure they use a high enough resolution clock to | |
634 | support irq time accounting and then call enable_sched_clock_irqtime(). | |
635 | ||
15626062 GS |
636 | config HAVE_ARCH_TRANSPARENT_HUGEPAGE |
637 | bool | |
638 | ||
a00cc7d9 MW |
639 | config HAVE_ARCH_TRANSPARENT_HUGEPAGE_PUD |
640 | bool | |
641 | ||
0ddab1d2 TK |
642 | config HAVE_ARCH_HUGE_VMAP |
643 | bool | |
644 | ||
0f8975ec PE |
645 | config HAVE_ARCH_SOFT_DIRTY |
646 | bool | |
647 | ||
786d35d4 DH |
648 | config HAVE_MOD_ARCH_SPECIFIC |
649 | bool | |
650 | help | |
651 | The arch uses struct mod_arch_specific to store data. Many arches | |
652 | just need a simple module loader without arch specific data - those | |
653 | should not enable this. | |
654 | ||
655 | config MODULES_USE_ELF_RELA | |
656 | bool | |
657 | help | |
658 | Modules only use ELF RELA relocations. Modules with ELF REL | |
659 | relocations will give an error. | |
660 | ||
661 | config MODULES_USE_ELF_REL | |
662 | bool | |
663 | help | |
664 | Modules only use ELF REL relocations. Modules with ELF RELA | |
665 | relocations will give an error. | |
666 | ||
b92021b0 RR |
667 | config HAVE_UNDERSCORE_SYMBOL_PREFIX |
668 | bool | |
669 | help | |
670 | Some architectures generate an _ in front of C symbols; things like | |
671 | module loading and assembly files need to know about this. | |
672 | ||
cc1f0274 FW |
673 | config HAVE_IRQ_EXIT_ON_IRQ_STACK |
674 | bool | |
675 | help | |
676 | Architecture doesn't only execute the irq handler on the irq stack | |
677 | but also irq_exit(). This way we can process softirqs on this irq | |
678 | stack instead of switching to a new one when we call __do_softirq() | |
679 | in the end of an hardirq. | |
680 | This spares a stack switch and improves cache usage on softirq | |
681 | processing. | |
682 | ||
235a8f02 KS |
683 | config PGTABLE_LEVELS |
684 | int | |
685 | default 2 | |
686 | ||
2b68f6ca KC |
687 | config ARCH_HAS_ELF_RANDOMIZE |
688 | bool | |
689 | help | |
690 | An architecture supports choosing randomized locations for | |
691 | stack, mmap, brk, and ET_DYN. Defined functions: | |
692 | - arch_mmap_rnd() | |
204db6ed | 693 | - arch_randomize_brk() |
2b68f6ca | 694 | |
d07e2259 DC |
695 | config HAVE_ARCH_MMAP_RND_BITS |
696 | bool | |
697 | help | |
698 | An arch should select this symbol if it supports setting a variable | |
699 | number of bits for use in establishing the base address for mmap | |
700 | allocations, has MMU enabled and provides values for both: | |
701 | - ARCH_MMAP_RND_BITS_MIN | |
702 | - ARCH_MMAP_RND_BITS_MAX | |
703 | ||
5f56a5df JS |
704 | config HAVE_EXIT_THREAD |
705 | bool | |
706 | help | |
707 | An architecture implements exit_thread. | |
708 | ||
d07e2259 DC |
709 | config ARCH_MMAP_RND_BITS_MIN |
710 | int | |
711 | ||
712 | config ARCH_MMAP_RND_BITS_MAX | |
713 | int | |
714 | ||
715 | config ARCH_MMAP_RND_BITS_DEFAULT | |
716 | int | |
717 | ||
718 | config ARCH_MMAP_RND_BITS | |
719 | int "Number of bits to use for ASLR of mmap base address" if EXPERT | |
720 | range ARCH_MMAP_RND_BITS_MIN ARCH_MMAP_RND_BITS_MAX | |
721 | default ARCH_MMAP_RND_BITS_DEFAULT if ARCH_MMAP_RND_BITS_DEFAULT | |
722 | default ARCH_MMAP_RND_BITS_MIN | |
723 | depends on HAVE_ARCH_MMAP_RND_BITS | |
724 | help | |
725 | This value can be used to select the number of bits to use to | |
726 | determine the random offset to the base address of vma regions | |
727 | resulting from mmap allocations. This value will be bounded | |
728 | by the architecture's minimum and maximum supported values. | |
729 | ||
730 | This value can be changed after boot using the | |
731 | /proc/sys/vm/mmap_rnd_bits tunable | |
732 | ||
733 | config HAVE_ARCH_MMAP_RND_COMPAT_BITS | |
734 | bool | |
735 | help | |
736 | An arch should select this symbol if it supports running applications | |
737 | in compatibility mode, supports setting a variable number of bits for | |
738 | use in establishing the base address for mmap allocations, has MMU | |
739 | enabled and provides values for both: | |
740 | - ARCH_MMAP_RND_COMPAT_BITS_MIN | |
741 | - ARCH_MMAP_RND_COMPAT_BITS_MAX | |
742 | ||
743 | config ARCH_MMAP_RND_COMPAT_BITS_MIN | |
744 | int | |
745 | ||
746 | config ARCH_MMAP_RND_COMPAT_BITS_MAX | |
747 | int | |
748 | ||
749 | config ARCH_MMAP_RND_COMPAT_BITS_DEFAULT | |
750 | int | |
751 | ||
752 | config ARCH_MMAP_RND_COMPAT_BITS | |
753 | int "Number of bits to use for ASLR of mmap base address for compatible applications" if EXPERT | |
754 | range ARCH_MMAP_RND_COMPAT_BITS_MIN ARCH_MMAP_RND_COMPAT_BITS_MAX | |
755 | default ARCH_MMAP_RND_COMPAT_BITS_DEFAULT if ARCH_MMAP_RND_COMPAT_BITS_DEFAULT | |
756 | default ARCH_MMAP_RND_COMPAT_BITS_MIN | |
757 | depends on HAVE_ARCH_MMAP_RND_COMPAT_BITS | |
758 | help | |
759 | This value can be used to select the number of bits to use to | |
760 | determine the random offset to the base address of vma regions | |
761 | resulting from mmap allocations for compatible applications This | |
762 | value will be bounded by the architecture's minimum and maximum | |
763 | supported values. | |
764 | ||
765 | This value can be changed after boot using the | |
766 | /proc/sys/vm/mmap_rnd_compat_bits tunable | |
767 | ||
1b028f78 DS |
768 | config HAVE_ARCH_COMPAT_MMAP_BASES |
769 | bool | |
770 | help | |
771 | This allows 64bit applications to invoke 32-bit mmap() syscall | |
772 | and vice-versa 32-bit applications to call 64-bit mmap(). | |
773 | Required for applications doing different bitness syscalls. | |
774 | ||
3033f14a JT |
775 | config HAVE_COPY_THREAD_TLS |
776 | bool | |
777 | help | |
778 | Architecture provides copy_thread_tls to accept tls argument via | |
779 | normal C parameter passing, rather than extracting the syscall | |
780 | argument from pt_regs. | |
781 | ||
b9ab5ebb JP |
782 | config HAVE_STACK_VALIDATION |
783 | bool | |
784 | help | |
785 | Architecture supports the 'objtool check' host tool command, which | |
786 | performs compile-time stack metadata validation. | |
787 | ||
af085d90 JP |
788 | config HAVE_RELIABLE_STACKTRACE |
789 | bool | |
790 | help | |
791 | Architecture has a save_stack_trace_tsk_reliable() function which | |
792 | only returns a stack trace if it can guarantee the trace is reliable. | |
793 | ||
468a9428 GS |
794 | config HAVE_ARCH_HASH |
795 | bool | |
796 | default n | |
797 | help | |
798 | If this is set, the architecture provides an <asm/hash.h> | |
799 | file which provides platform-specific implementations of some | |
800 | functions in <linux/hash.h> or fs/namei.c. | |
801 | ||
3a495511 WBG |
802 | config ISA_BUS_API |
803 | def_bool ISA | |
804 | ||
d2125043 AV |
805 | # |
806 | # ABI hall of shame | |
807 | # | |
808 | config CLONE_BACKWARDS | |
809 | bool | |
810 | help | |
811 | Architecture has tls passed as the 4th argument of clone(2), | |
812 | not the 5th one. | |
813 | ||
814 | config CLONE_BACKWARDS2 | |
815 | bool | |
816 | help | |
817 | Architecture has the first two arguments of clone(2) swapped. | |
818 | ||
dfa9771a MS |
819 | config CLONE_BACKWARDS3 |
820 | bool | |
821 | help | |
822 | Architecture has tls passed as the 3rd argument of clone(2), | |
823 | not the 5th one. | |
824 | ||
eaca6eae AV |
825 | config ODD_RT_SIGACTION |
826 | bool | |
827 | help | |
828 | Architecture has unusual rt_sigaction(2) arguments | |
829 | ||
0a0e8cdf AV |
830 | config OLD_SIGSUSPEND |
831 | bool | |
832 | help | |
833 | Architecture has old sigsuspend(2) syscall, of one-argument variety | |
834 | ||
835 | config OLD_SIGSUSPEND3 | |
836 | bool | |
837 | help | |
838 | Even weirder antique ABI - three-argument sigsuspend(2) | |
839 | ||
495dfbf7 AV |
840 | config OLD_SIGACTION |
841 | bool | |
842 | help | |
843 | Architecture has old sigaction(2) syscall. Nope, not the same | |
844 | as OLD_SIGSUSPEND | OLD_SIGSUSPEND3 - alpha has sigsuspend(2), | |
845 | but fairly different variant of sigaction(2), thanks to OSF/1 | |
846 | compatibility... | |
847 | ||
848 | config COMPAT_OLD_SIGACTION | |
849 | bool | |
850 | ||
0d4a619b CH |
851 | config ARCH_NO_COHERENT_DMA_MMAP |
852 | bool | |
853 | ||
fff7fb0b ZZ |
854 | config CPU_NO_EFFICIENT_FFS |
855 | def_bool n | |
856 | ||
ba14a194 AL |
857 | config HAVE_ARCH_VMAP_STACK |
858 | def_bool n | |
859 | help | |
860 | An arch should select this symbol if it can support kernel stacks | |
861 | in vmalloc space. This means: | |
862 | ||
863 | - vmalloc space must be large enough to hold many kernel stacks. | |
864 | This may rule out many 32-bit architectures. | |
865 | ||
866 | - Stacks in vmalloc space need to work reliably. For example, if | |
867 | vmap page tables are created on demand, either this mechanism | |
868 | needs to work while the stack points to a virtual address with | |
869 | unpopulated page tables or arch code (switch_to() and switch_mm(), | |
870 | most likely) needs to ensure that the stack's page table entries | |
871 | are populated before running on a possibly unpopulated stack. | |
872 | ||
873 | - If the stack overflows into a guard page, something reasonable | |
874 | should happen. The definition of "reasonable" is flexible, but | |
875 | instantly rebooting without logging anything would be unfriendly. | |
876 | ||
877 | config VMAP_STACK | |
878 | default y | |
879 | bool "Use a virtually-mapped stack" | |
880 | depends on HAVE_ARCH_VMAP_STACK && !KASAN | |
881 | ---help--- | |
882 | Enable this if you want the use virtually-mapped kernel stacks | |
883 | with guard pages. This causes kernel stack overflows to be | |
884 | caught immediately rather than causing difficult-to-diagnose | |
885 | corruption. | |
886 | ||
887 | This is presently incompatible with KASAN because KASAN expects | |
888 | the stack to map directly to the KASAN shadow map using a formula | |
889 | that is incorrect if the stack is in vmalloc space. | |
890 | ||
ad21fc4f LA |
891 | config ARCH_OPTIONAL_KERNEL_RWX |
892 | def_bool n | |
893 | ||
894 | config ARCH_OPTIONAL_KERNEL_RWX_DEFAULT | |
895 | def_bool n | |
896 | ||
897 | config ARCH_HAS_STRICT_KERNEL_RWX | |
898 | def_bool n | |
899 | ||
0f5bf6d0 | 900 | config STRICT_KERNEL_RWX |
ad21fc4f LA |
901 | bool "Make kernel text and rodata read-only" if ARCH_OPTIONAL_KERNEL_RWX |
902 | depends on ARCH_HAS_STRICT_KERNEL_RWX | |
903 | default !ARCH_OPTIONAL_KERNEL_RWX || ARCH_OPTIONAL_KERNEL_RWX_DEFAULT | |
904 | help | |
905 | If this is set, kernel text and rodata memory will be made read-only, | |
906 | and non-text memory will be made non-executable. This provides | |
907 | protection against certain security exploits (e.g. executing the heap | |
908 | or modifying text) | |
909 | ||
910 | These features are considered standard security practice these days. | |
911 | You should say Y here in almost all cases. | |
912 | ||
913 | config ARCH_HAS_STRICT_MODULE_RWX | |
914 | def_bool n | |
915 | ||
0f5bf6d0 | 916 | config STRICT_MODULE_RWX |
ad21fc4f LA |
917 | bool "Set loadable kernel module data as NX and text as RO" if ARCH_OPTIONAL_KERNEL_RWX |
918 | depends on ARCH_HAS_STRICT_MODULE_RWX && MODULES | |
919 | default !ARCH_OPTIONAL_KERNEL_RWX || ARCH_OPTIONAL_KERNEL_RWX_DEFAULT | |
920 | help | |
921 | If this is set, module text and rodata memory will be made read-only, | |
922 | and non-text memory will be made non-executable. This provides | |
923 | protection against certain security exploits (e.g. writing to text) | |
924 | ||
1a8b6d76 MW |
925 | config ARCH_WANT_RELAX_ORDER |
926 | bool | |
927 | ||
fd25d19f KC |
928 | config REFCOUNT_FULL |
929 | bool "Perform full reference count validation at the expense of speed" | |
930 | help | |
931 | Enabling this switches the refcounting infrastructure from a fast | |
932 | unchecked atomic_t implementation to a fully state checked | |
933 | implementation, which can be (slightly) slower but provides protections | |
934 | against various use-after-free conditions that can be used in | |
935 | security flaw exploits. | |
936 | ||
2521f2c2 | 937 | source "kernel/gcov/Kconfig" |