1 # SPDX-License-Identifier: GPL-2.0 1 # SPDX-License-Identifier: GPL-2.0
2 # 2 #
3 # General architecture dependent options 3 # General architecture dependent options
4 # 4 #
5 5
6 # !! 6 config CRASH_CORE
7 # Note: arch/$(SRCARCH)/Kconfig needs to be in <<
8 # override the default values in this file. <<
9 # <<
10 source "arch/$(SRCARCH)/Kconfig" <<
11 <<
12 config ARCH_CONFIGURES_CPU_MITIGATIONS <<
13 bool 7 bool
14 8
15 if !ARCH_CONFIGURES_CPU_MITIGATIONS !! 9 config KEXEC_CORE
16 config CPU_MITIGATIONS !! 10 select CRASH_CORE
17 def_bool y <<
18 endif <<
19 <<
20 menu "General architecture-dependent options" <<
21 <<
22 config ARCH_HAS_SUBPAGE_FAULTS <<
23 bool 11 bool
24 help <<
25 Select if the architecture can check <<
26 granularity (e.g. arm64 MTE). The pr <<
27 must be implemented. <<
28 12
29 config HOTPLUG_SMT !! 13 config HAVE_IMA_KEXEC
30 bool 14 bool
31 15
32 config SMT_NUM_THREADS_DYNAMIC !! 16 config HOTPLUG_SMT
33 bool 17 bool
34 18
35 # Selected by HOTPLUG_CORE_SYNC_DEAD or HOTPLU !! 19 config OPROFILE
36 config HOTPLUG_CORE_SYNC !! 20 tristate "OProfile system profiling"
37 bool !! 21 depends on PROFILING
>> 22 depends on HAVE_OPROFILE
>> 23 select RING_BUFFER
>> 24 select RING_BUFFER_ALLOW_SWAP
>> 25 help
>> 26 OProfile is a profiling system capable of profiling the
>> 27 whole system, include the kernel, kernel modules, libraries,
>> 28 and applications.
38 29
39 # Basic CPU dead synchronization selected by a !! 30 If unsure, say N.
40 config HOTPLUG_CORE_SYNC_DEAD <<
41 bool <<
42 select HOTPLUG_CORE_SYNC <<
43 31
44 # Full CPU synchronization with alive state se !! 32 config OPROFILE_EVENT_MULTIPLEX
45 config HOTPLUG_CORE_SYNC_FULL !! 33 bool "OProfile multiplexing support (EXPERIMENTAL)"
46 bool !! 34 default n
47 select HOTPLUG_CORE_SYNC_DEAD if HOTPL !! 35 depends on OPROFILE && X86
48 select HOTPLUG_CORE_SYNC !! 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
>> 40 between events at a user specified time interval.
49 41
50 config HOTPLUG_SPLIT_STARTUP !! 42 If unsure, say N.
51 bool <<
52 select HOTPLUG_CORE_SYNC_FULL <<
53 43
54 config HOTPLUG_PARALLEL !! 44 config HAVE_OPROFILE
55 bool 45 bool
56 select HOTPLUG_SPLIT_STARTUP <<
57 46
58 config GENERIC_ENTRY !! 47 config OPROFILE_NMI_TIMER
59 bool !! 48 def_bool y
>> 49 depends on PERF_EVENTS && HAVE_PERF_EVENTS_NMI && !PPC64
60 50
61 config KPROBES 51 config KPROBES
62 bool "Kprobes" 52 bool "Kprobes"
>> 53 depends on MODULES
63 depends on HAVE_KPROBES 54 depends on HAVE_KPROBES
64 select KALLSYMS 55 select KALLSYMS
65 select EXECMEM <<
66 select NEED_TASKS_RCU <<
67 help 56 help
68 Kprobes allows you to trap at almost 57 Kprobes allows you to trap at almost any kernel address and
69 execute a callback function. regist 58 execute a callback function. register_kprobe() establishes
70 a probepoint and specifies the callb 59 a probepoint and specifies the callback. Kprobes is useful
71 for kernel debugging, non-intrusive 60 for kernel debugging, non-intrusive instrumentation and testing.
72 If in doubt, say "N". 61 If in doubt, say "N".
73 62
74 config JUMP_LABEL 63 config JUMP_LABEL
75 bool "Optimize very unlikely/likely br !! 64 bool "Optimize very unlikely/likely branches"
76 depends on HAVE_ARCH_JUMP_LABEL !! 65 depends on HAVE_ARCH_JUMP_LABEL
77 select OBJTOOL if HAVE_JUMP_LABEL_HACK !! 66 help
78 help !! 67 This option enables a transparent branch optimization that
79 This option enables a transparent br !! 68 makes certain almost-always-true or almost-always-false branch
80 makes certain almost-always-true or !! 69 conditions even cheaper to execute within the kernel.
81 conditions even cheaper to execute w !! 70
82 !! 71 Certain performance-sensitive kernel code, such as trace points,
83 Certain performance-sensitive kernel !! 72 scheduler functionality, networking code and KVM have such
84 scheduler functionality, networking !! 73 branches and include support for this optimization technique.
85 branches and include support for thi !! 74
86 !! 75 If it is detected that the compiler has support for "asm goto",
87 If it is detected that the compiler !! 76 the kernel will compile such branches with just a nop
88 the kernel will compile such branche !! 77 instruction. When the condition flag is toggled to true, the
89 instruction. When the condition flag !! 78 nop will be converted to a jump instruction to execute the
90 nop will be converted to a jump inst !! 79 conditional block of instructions.
91 conditional block of instructions. !! 80
92 !! 81 This technique lowers overhead and stress on the branch prediction
93 This technique lowers overhead and s !! 82 of the processor and generally makes the kernel faster. The update
94 of the processor and generally makes !! 83 of the condition is slower, but those are always very rare.
95 of the condition is slower, but thos <<
96 84
97 ( On 32-bit x86, the necessary optio !! 85 ( On 32-bit x86, the necessary options added to the compiler
98 flags may increase the size of the !! 86 flags may increase the size of the kernel slightly. )
99 87
100 config STATIC_KEYS_SELFTEST 88 config STATIC_KEYS_SELFTEST
101 bool "Static key selftest" 89 bool "Static key selftest"
102 depends on JUMP_LABEL 90 depends on JUMP_LABEL
103 help 91 help
104 Boot time self-test of the branch pa 92 Boot time self-test of the branch patching code.
105 93
106 config STATIC_CALL_SELFTEST <<
107 bool "Static call selftest" <<
108 depends on HAVE_STATIC_CALL <<
109 help <<
110 Boot time self-test of the call patc <<
111 <<
112 config OPTPROBES 94 config OPTPROBES
113 def_bool y 95 def_bool y
114 depends on KPROBES && HAVE_OPTPROBES 96 depends on KPROBES && HAVE_OPTPROBES
115 select NEED_TASKS_RCU !! 97 select TASKS_RCU if PREEMPT
116 98
117 config KPROBES_ON_FTRACE 99 config KPROBES_ON_FTRACE
118 def_bool y 100 def_bool y
119 depends on KPROBES && HAVE_KPROBES_ON_ 101 depends on KPROBES && HAVE_KPROBES_ON_FTRACE
120 depends on DYNAMIC_FTRACE_WITH_REGS 102 depends on DYNAMIC_FTRACE_WITH_REGS
121 help 103 help
122 If function tracer is enabled and th !! 104 If function tracer is enabled and the arch supports full
123 passing of pt_regs to function traci !! 105 passing of pt_regs to function tracing, then kprobes can
124 optimize on top of function tracing. !! 106 optimize on top of function tracing.
125 107
126 config UPROBES 108 config UPROBES
127 def_bool n 109 def_bool n
128 depends on ARCH_SUPPORTS_UPROBES 110 depends on ARCH_SUPPORTS_UPROBES
129 help 111 help
130 Uprobes is the user-space counterpar 112 Uprobes is the user-space counterpart to kprobes: they
131 enable instrumentation applications 113 enable instrumentation applications (such as 'perf probe')
132 to establish unintrusive probes in u 114 to establish unintrusive probes in user-space binaries and
133 libraries, by executing handler func 115 libraries, by executing handler functions when the probes
134 are hit by user-space applications. 116 are hit by user-space applications.
135 117
136 ( These probes come in the form of s 118 ( These probes come in the form of single-byte breakpoints,
137 managed by the kernel and kept tra 119 managed by the kernel and kept transparent to the probed
138 application. ) 120 application. )
139 121
140 config HAVE_64BIT_ALIGNED_ACCESS 122 config HAVE_64BIT_ALIGNED_ACCESS
141 def_bool 64BIT && !HAVE_EFFICIENT_UNAL 123 def_bool 64BIT && !HAVE_EFFICIENT_UNALIGNED_ACCESS
142 help 124 help
143 Some architectures require 64 bit ac 125 Some architectures require 64 bit accesses to be 64 bit
144 aligned, which also requires structs 126 aligned, which also requires structs containing 64 bit values
145 to be 64 bit aligned too. This inclu 127 to be 64 bit aligned too. This includes some 32 bit
146 architectures which can do 64 bit ac 128 architectures which can do 64 bit accesses, as well as 64 bit
147 architectures without unaligned acce 129 architectures without unaligned access.
148 130
149 This symbol should be selected by an 131 This symbol should be selected by an architecture if 64 bit
150 accesses are required to be 64 bit a 132 accesses are required to be 64 bit aligned in this way even
151 though it is not a 64 bit architectu 133 though it is not a 64 bit architecture.
152 134
153 See Documentation/core-api/unaligned !! 135 See Documentation/unaligned-memory-access.txt for more
154 more information on the topic of una !! 136 information on the topic of unaligned memory accesses.
155 137
156 config HAVE_EFFICIENT_UNALIGNED_ACCESS 138 config HAVE_EFFICIENT_UNALIGNED_ACCESS
157 bool 139 bool
158 help 140 help
159 Some architectures are unable to per 141 Some architectures are unable to perform unaligned accesses
160 without the use of get_unaligned/put 142 without the use of get_unaligned/put_unaligned. Others are
161 unable to perform such accesses effi 143 unable to perform such accesses efficiently (e.g. trap on
162 unaligned access and require fixing 144 unaligned access and require fixing it up in the exception
163 handler.) 145 handler.)
164 146
165 This symbol should be selected by an 147 This symbol should be selected by an architecture if it can
166 perform unaligned accesses efficient 148 perform unaligned accesses efficiently to allow different
167 code paths to be selected for these 149 code paths to be selected for these cases. Some network
168 drivers, for example, could opt to n 150 drivers, for example, could opt to not fix up alignment
169 problems with received packets if do 151 problems with received packets if doing so would not help
170 much. 152 much.
171 153
172 See Documentation/core-api/unaligned !! 154 See Documentation/unaligned-memory-access.txt for more
173 information on the topic of unaligne 155 information on the topic of unaligned memory accesses.
174 156
175 config ARCH_USE_BUILTIN_BSWAP 157 config ARCH_USE_BUILTIN_BSWAP
176 bool !! 158 bool
177 help !! 159 help
178 Modern versions of GCC (since 4.4) h !! 160 Modern versions of GCC (since 4.4) have builtin functions
179 for handling byte-swapping. Using th !! 161 for handling byte-swapping. Using these, instead of the old
180 inline assembler that the architectu !! 162 inline assembler that the architecture code provides in the
181 __arch_bswapXX() macros, allows the !! 163 __arch_bswapXX() macros, allows the compiler to see what's
182 happening and offers more opportunit !! 164 happening and offers more opportunity for optimisation. In
183 particular, the compiler will be abl !! 165 particular, the compiler will be able to combine the byteswap
184 with a nearby load or store and use !! 166 with a nearby load or store and use load-and-swap or
185 store-and-swap instructions if the a !! 167 store-and-swap instructions if the architecture has them. It
186 should almost *never* result in code !! 168 should almost *never* result in code which is worse than the
187 hand-coded assembler in <asm/swab.h> !! 169 hand-coded assembler in <asm/swab.h>. But just in case it
188 does, the use of the builtins is opt !! 170 does, the use of the builtins is optional.
189 !! 171
190 Any architecture with load-and-swap !! 172 Any architecture with load-and-swap or store-and-swap
191 instructions should set this. And it !! 173 instructions should set this. And it shouldn't hurt to set it
192 on architectures that don't have suc !! 174 on architectures that don't have such instructions.
193 175
194 config KRETPROBES 176 config KRETPROBES
195 def_bool y 177 def_bool y
196 depends on KPROBES && (HAVE_KRETPROBES !! 178 depends on KPROBES && HAVE_KRETPROBES
197 <<
198 config KRETPROBE_ON_RETHOOK <<
199 def_bool y <<
200 depends on HAVE_RETHOOK <<
201 depends on KRETPROBES <<
202 select RETHOOK <<
203 179
204 config USER_RETURN_NOTIFIER 180 config USER_RETURN_NOTIFIER
205 bool 181 bool
206 depends on HAVE_USER_RETURN_NOTIFIER 182 depends on HAVE_USER_RETURN_NOTIFIER
207 help 183 help
208 Provide a kernel-internal notificati 184 Provide a kernel-internal notification when a cpu is about to
209 switch to user mode. 185 switch to user mode.
210 186
211 config HAVE_IOREMAP_PROT 187 config HAVE_IOREMAP_PROT
212 bool 188 bool
213 189
214 config HAVE_KPROBES 190 config HAVE_KPROBES
215 bool 191 bool
216 192
217 config HAVE_KRETPROBES 193 config HAVE_KRETPROBES
218 bool 194 bool
219 195
220 config HAVE_OPTPROBES 196 config HAVE_OPTPROBES
221 bool 197 bool
222 198
223 config HAVE_KPROBES_ON_FTRACE 199 config HAVE_KPROBES_ON_FTRACE
224 bool 200 bool
225 201
226 config ARCH_CORRECT_STACKTRACE_ON_KRETPROBE <<
227 bool <<
228 help <<
229 Since kretprobes modifies return add <<
230 stacktrace may see the kretprobe tra <<
231 of correct one. If the architecture <<
232 unwinder can adjust such entries, se <<
233 <<
234 config HAVE_FUNCTION_ERROR_INJECTION 202 config HAVE_FUNCTION_ERROR_INJECTION
235 bool 203 bool
236 204
237 config HAVE_NMI 205 config HAVE_NMI
238 bool 206 bool
239 207
240 config HAVE_FUNCTION_DESCRIPTORS <<
241 bool <<
242 <<
243 config TRACE_IRQFLAGS_SUPPORT <<
244 bool <<
245 <<
246 config TRACE_IRQFLAGS_NMI_SUPPORT <<
247 bool <<
248 <<
249 # 208 #
250 # An arch should select this if it provides al 209 # An arch should select this if it provides all these things:
251 # 210 #
252 # task_pt_regs() in asm/process 211 # task_pt_regs() in asm/processor.h or asm/ptrace.h
253 # arch_has_single_step() if there is ha 212 # arch_has_single_step() if there is hardware single-step support
254 # arch_has_block_step() if there is ha 213 # arch_has_block_step() if there is hardware block-step support
255 # asm/syscall.h supplying asm- 214 # asm/syscall.h supplying asm-generic/syscall.h interface
256 # linux/regset.h user_regset in 215 # linux/regset.h user_regset interfaces
257 # CORE_DUMP_USE_REGSET #define'd in l 216 # CORE_DUMP_USE_REGSET #define'd in linux/elf.h
258 # TIF_SYSCALL_TRACE calls ptrace_r !! 217 # TIF_SYSCALL_TRACE calls tracehook_report_syscall_{entry,exit}
259 # TIF_NOTIFY_RESUME calls resume_u !! 218 # TIF_NOTIFY_RESUME calls tracehook_notify_resume()
>> 219 # signal delivery calls tracehook_signal_handler()
260 # 220 #
261 config HAVE_ARCH_TRACEHOOK 221 config HAVE_ARCH_TRACEHOOK
262 bool 222 bool
263 223
264 config HAVE_DMA_CONTIGUOUS 224 config HAVE_DMA_CONTIGUOUS
265 bool 225 bool
266 226
267 config GENERIC_SMP_IDLE_THREAD 227 config GENERIC_SMP_IDLE_THREAD
268 bool !! 228 bool
269 229
270 config GENERIC_IDLE_POLL_SETUP 230 config GENERIC_IDLE_POLL_SETUP
271 bool !! 231 bool
272 232
273 config ARCH_HAS_FORTIFY_SOURCE 233 config ARCH_HAS_FORTIFY_SOURCE
274 bool 234 bool
275 help 235 help
276 An architecture should select this w 236 An architecture should select this when it can successfully
277 build and run with CONFIG_FORTIFY_SO 237 build and run with CONFIG_FORTIFY_SOURCE.
278 238
279 # <<
280 # Select if the arch provides a historic keepi <<
281 # command line option <<
282 # <<
283 config ARCH_HAS_KEEPINITRD <<
284 bool <<
285 <<
286 # Select if arch has all set_memory_ro/rw/x/nx 239 # Select if arch has all set_memory_ro/rw/x/nx() functions in asm/cacheflush.h
287 config ARCH_HAS_SET_MEMORY 240 config ARCH_HAS_SET_MEMORY
288 bool 241 bool
289 242
290 # Select if arch has all set_direct_map_invali !! 243 # Select if arch init_task must go in the __init_task_data section
291 config ARCH_HAS_SET_DIRECT_MAP !! 244 config ARCH_TASK_STRUCT_ON_STACK
292 bool !! 245 bool
293 <<
294 # <<
295 # Select if the architecture provides the arch <<
296 # either provide an uncached segment alias for <<
297 # to remap the page tables in place. <<
298 # <<
299 config ARCH_HAS_DMA_SET_UNCACHED <<
300 bool <<
301 <<
302 # <<
303 # Select if the architectures provides the arc <<
304 # to undo an in-place page table remap for unc <<
305 # <<
306 config ARCH_HAS_DMA_CLEAR_UNCACHED <<
307 bool <<
308 246
309 config ARCH_HAS_CPU_FINALIZE_INIT !! 247 # Select if arch has its private alloc_task_struct() function
>> 248 config ARCH_TASK_STRUCT_ALLOCATOR
310 bool 249 bool
311 250
312 # The architecture has a per-task state that i <<
313 config ARCH_HAS_CPU_PASID <<
314 bool <<
315 select IOMMU_MM_DATA <<
316 <<
317 config HAVE_ARCH_THREAD_STRUCT_WHITELIST 251 config HAVE_ARCH_THREAD_STRUCT_WHITELIST
318 bool 252 bool
>> 253 depends on !ARCH_TASK_STRUCT_ALLOCATOR
319 help 254 help
320 An architecture should select this t 255 An architecture should select this to provide hardened usercopy
321 knowledge about what region of the t 256 knowledge about what region of the thread_struct should be
322 whitelisted for copying to userspace 257 whitelisted for copying to userspace. Normally this is only the
323 FPU registers. Specifically, arch_th 258 FPU registers. Specifically, arch_thread_struct_whitelist()
324 should be implemented. Without this, 259 should be implemented. Without this, the entire thread_struct
325 field in task_struct will be left wh 260 field in task_struct will be left whitelisted.
326 261
327 # Select if arch wants to size task_struct dyn !! 262 # Select if arch has its private alloc_thread_stack() function
328 config ARCH_WANTS_DYNAMIC_TASK_STRUCT !! 263 config ARCH_THREAD_STACK_ALLOCATOR
329 bool <<
330 <<
331 config ARCH_WANTS_NO_INSTR <<
332 bool <<
333 help <<
334 An architecture should select this i <<
335 functions to denote that the toolcha <<
336 functions and is required for correc <<
337 <<
338 config ARCH_32BIT_OFF_T <<
339 bool 264 bool
340 depends on !64BIT <<
341 help <<
342 All new 32-bit architectures should <<
343 userspace side which corresponds to <<
344 is the requirement for modern ABIs. <<
345 still support 32-bit off_t. This opt <<
346 architectures explicitly. <<
347 265
348 # Selected by 64 bit architectures which have !! 266 # Select if arch wants to size task_struct dynamically via arch_task_struct_size:
349 config ARCH_32BIT_USTAT_F_TINODE !! 267 config ARCH_WANTS_DYNAMIC_TASK_STRUCT
350 bool <<
351 <<
352 config HAVE_ASM_MODVERSIONS <<
353 bool 268 bool
354 help <<
355 This symbol should be selected by an <<
356 <asm/asm-prototypes.h> to support th <<
357 exported from assembly code. <<
358 269
359 config HAVE_REGS_AND_STACK_ACCESS_API 270 config HAVE_REGS_AND_STACK_ACCESS_API
360 bool 271 bool
361 help 272 help
362 This symbol should be selected by an !! 273 This symbol should be selected by an architecure if it supports
363 the API needed to access registers a 274 the API needed to access registers and stack entries from pt_regs,
364 declared in asm/ptrace.h 275 declared in asm/ptrace.h
365 For example the kprobes-based event 276 For example the kprobes-based event tracer needs this API.
366 277
367 config HAVE_RSEQ 278 config HAVE_RSEQ
368 bool 279 bool
369 depends on HAVE_REGS_AND_STACK_ACCESS_ 280 depends on HAVE_REGS_AND_STACK_ACCESS_API
370 help 281 help
371 This symbol should be selected by an 282 This symbol should be selected by an architecture if it
372 supports an implementation of restar 283 supports an implementation of restartable sequences.
373 284
374 config HAVE_RUST !! 285 config HAVE_CLK
375 bool <<
376 help <<
377 This symbol should be selected by an <<
378 supports Rust. <<
379 <<
380 config HAVE_FUNCTION_ARG_ACCESS_API <<
381 bool 286 bool
382 help 287 help
383 This symbol should be selected by an !! 288 The <linux/clk.h> calls support software clock gating and
384 the API needed to access function ar !! 289 thus are a key power management tool on many systems.
385 declared in asm/ptrace.h <<
386 290
387 config HAVE_HW_BREAKPOINT 291 config HAVE_HW_BREAKPOINT
388 bool 292 bool
389 depends on PERF_EVENTS 293 depends on PERF_EVENTS
390 294
391 config HAVE_MIXED_BREAKPOINTS_REGS 295 config HAVE_MIXED_BREAKPOINTS_REGS
392 bool 296 bool
393 depends on HAVE_HW_BREAKPOINT 297 depends on HAVE_HW_BREAKPOINT
394 help 298 help
395 Depending on the arch implementation 299 Depending on the arch implementation of hardware breakpoints,
396 some of them have separate registers 300 some of them have separate registers for data and instruction
397 breakpoints addresses, others have m 301 breakpoints addresses, others have mixed registers to store
398 them but define the access type in a 302 them but define the access type in a control register.
399 Select this option if your arch impl 303 Select this option if your arch implements breakpoints under the
400 latter fashion. 304 latter fashion.
401 305
402 config HAVE_USER_RETURN_NOTIFIER 306 config HAVE_USER_RETURN_NOTIFIER
403 bool 307 bool
404 308
405 config HAVE_PERF_EVENTS_NMI 309 config HAVE_PERF_EVENTS_NMI
406 bool 310 bool
407 help 311 help
408 System hardware can generate an NMI 312 System hardware can generate an NMI using the perf event
409 subsystem. Also has support for cal 313 subsystem. Also has support for calculating CPU cycle events
410 to determine how many clock cycles i 314 to determine how many clock cycles in a given period.
411 315
412 config HAVE_HARDLOCKUP_DETECTOR_PERF 316 config HAVE_HARDLOCKUP_DETECTOR_PERF
413 bool 317 bool
414 depends on HAVE_PERF_EVENTS_NMI 318 depends on HAVE_PERF_EVENTS_NMI
415 help 319 help
416 The arch chooses to use the generic 320 The arch chooses to use the generic perf-NMI-based hardlockup
417 detector. Must define HAVE_PERF_EVEN 321 detector. Must define HAVE_PERF_EVENTS_NMI.
418 322
419 config HAVE_HARDLOCKUP_DETECTOR_ARCH !! 323 config HAVE_NMI_WATCHDOG
>> 324 depends on HAVE_NMI
420 bool 325 bool
421 help 326 help
422 The arch provides its own hardlockup !! 327 The arch provides a low level NMI watchdog. It provides
423 of the generic ones. !! 328 asm/nmi.h, and defines its own arch_touch_nmi_watchdog().
424 329
425 It uses the same command line parame !! 330 config HAVE_HARDLOCKUP_DETECTOR_ARCH
426 as the generic hardlockup detectors. !! 331 bool
>> 332 select HAVE_NMI_WATCHDOG
>> 333 help
>> 334 The arch chooses to provide its own hardlockup detector, which is
>> 335 a superset of the HAVE_NMI_WATCHDOG. It also conforms to config
>> 336 interfaces and parameters provided by hardlockup detector subsystem.
427 337
428 config HAVE_PERF_REGS 338 config HAVE_PERF_REGS
429 bool 339 bool
430 help 340 help
431 Support selective register dumps for 341 Support selective register dumps for perf events. This includes
432 bit-mapping of each registers and a 342 bit-mapping of each registers and a unique architecture id.
433 343
434 config HAVE_PERF_USER_STACK_DUMP 344 config HAVE_PERF_USER_STACK_DUMP
435 bool 345 bool
436 help 346 help
437 Support user stack dumps for perf ev 347 Support user stack dumps for perf event samples. This needs
438 access to the user stack pointer whi 348 access to the user stack pointer which is not unified across
439 architectures. 349 architectures.
440 350
441 config HAVE_ARCH_JUMP_LABEL 351 config HAVE_ARCH_JUMP_LABEL
442 bool 352 bool
443 353
444 config HAVE_ARCH_JUMP_LABEL_RELATIVE !! 354 config HAVE_RCU_TABLE_FREE
445 bool <<
446 <<
447 config MMU_GATHER_TABLE_FREE <<
448 bool <<
449 <<
450 config MMU_GATHER_RCU_TABLE_FREE <<
451 bool <<
452 select MMU_GATHER_TABLE_FREE <<
453 <<
454 config MMU_GATHER_PAGE_SIZE <<
455 bool <<
456 <<
457 config MMU_GATHER_NO_RANGE <<
458 bool <<
459 select MMU_GATHER_MERGE_VMAS <<
460 <<
461 config MMU_GATHER_NO_FLUSH_CACHE <<
462 bool <<
463 <<
464 config MMU_GATHER_MERGE_VMAS <<
465 bool <<
466 <<
467 config MMU_GATHER_NO_GATHER <<
468 bool 355 bool
469 depends on MMU_GATHER_TABLE_FREE <<
470 356
471 config ARCH_WANT_IRQS_OFF_ACTIVATE_MM !! 357 config HAVE_RCU_TABLE_INVALIDATE
472 bool <<
473 help <<
474 Temporary select until all architect <<
475 irqs disabled over activate_mm. Arch <<
476 shootdowns should enable this. <<
477 <<
478 # Use normal mm refcounting for MMU_LAZY_TLB k <<
479 # MMU_LAZY_TLB_REFCOUNT=n can improve the scal <<
480 # to/from kernel threads when the same mm is r <<
481 # multi-threaded application), by reducing con <<
482 # <<
483 # This can be disabled if the architecture ens <<
484 # "lazy tlb" beyond its final refcount (i.e., <<
485 # or its kernel page tables). This could be ar <<
486 # final exit(2) TLB flush, for example. <<
487 # <<
488 # To implement this, an arch *must*: <<
489 # Ensure the _lazy_tlb variants of mmgrab/mmdr <<
490 # the lazy tlb reference of a kthread's ->acti <<
491 # converted already). <<
492 config MMU_LAZY_TLB_REFCOUNT <<
493 def_bool y <<
494 depends on !MMU_LAZY_TLB_SHOOTDOWN <<
495 <<
496 # This option allows MMU_LAZY_TLB_REFCOUNT=n. <<
497 # mm as a lazy tlb beyond its last reference c <<
498 # users before the mm is deallocated. __mmdrop <<
499 # be using the mm as a lazy tlb, so that they <<
500 # init_mm for their active mm. mm_cpumask(mm) <<
501 # may be using mm as a lazy tlb mm. <<
502 # <<
503 # To implement this, an arch *must*: <<
504 # - At the time of the final mmdrop of the mm, <<
505 # at least all possible CPUs in which the mm <<
506 # - It must meet the requirements for MMU_LAZY <<
507 config MMU_LAZY_TLB_SHOOTDOWN <<
508 bool 358 bool
509 359
510 config ARCH_HAVE_NMI_SAFE_CMPXCHG 360 config ARCH_HAVE_NMI_SAFE_CMPXCHG
511 bool 361 bool
512 362
513 config ARCH_HAVE_EXTRA_ELF_NOTES <<
514 bool <<
515 help <<
516 An architecture should select this i <<
517 arch-specific ELF note section to co <<
518 functions: elf_coredump_extra_notes_ <<
519 elf_coredump_extra_notes_write() whi <<
520 dumper. <<
521 <<
522 config ARCH_HAS_NMI_SAFE_THIS_CPU_OPS <<
523 bool <<
524 <<
525 config HAVE_ALIGNED_STRUCT_PAGE 363 config HAVE_ALIGNED_STRUCT_PAGE
526 bool 364 bool
527 help 365 help
528 This makes sure that struct pages ar 366 This makes sure that struct pages are double word aligned and that
529 e.g. the SLUB allocator can perform 367 e.g. the SLUB allocator can perform double word atomic operations
530 on a struct page for better performa 368 on a struct page for better performance. However selecting this
531 might increase the size of a struct 369 might increase the size of a struct page by a word.
532 370
533 config HAVE_CMPXCHG_LOCAL 371 config HAVE_CMPXCHG_LOCAL
534 bool 372 bool
535 373
536 config HAVE_CMPXCHG_DOUBLE 374 config HAVE_CMPXCHG_DOUBLE
537 bool 375 bool
538 376
539 config ARCH_WEAK_RELEASE_ACQUIRE 377 config ARCH_WEAK_RELEASE_ACQUIRE
540 bool 378 bool
541 379
542 config ARCH_WANT_IPC_PARSE_VERSION 380 config ARCH_WANT_IPC_PARSE_VERSION
543 bool 381 bool
544 382
545 config ARCH_WANT_COMPAT_IPC_PARSE_VERSION 383 config ARCH_WANT_COMPAT_IPC_PARSE_VERSION
546 bool 384 bool
547 385
548 config ARCH_WANT_OLD_COMPAT_IPC 386 config ARCH_WANT_OLD_COMPAT_IPC
549 select ARCH_WANT_COMPAT_IPC_PARSE_VERS 387 select ARCH_WANT_COMPAT_IPC_PARSE_VERSION
550 bool 388 bool
551 389
552 config HAVE_ARCH_SECCOMP <<
553 bool <<
554 help <<
555 An arch should select this symbol to <<
556 syscall policy), and must provide an <<
557 and compat syscalls if the asm-gener <<
558 - __NR_seccomp_read_32 <<
559 - __NR_seccomp_write_32 <<
560 - __NR_seccomp_exit_32 <<
561 - __NR_seccomp_sigreturn_32 <<
562 <<
563 config HAVE_ARCH_SECCOMP_FILTER 390 config HAVE_ARCH_SECCOMP_FILTER
564 bool 391 bool
565 select HAVE_ARCH_SECCOMP <<
566 help 392 help
567 An arch should select this symbol if 393 An arch should select this symbol if it provides all of these things:
568 - all the requirements for HAVE_ARCH <<
569 - syscall_get_arch() 394 - syscall_get_arch()
570 - syscall_get_arguments() 395 - syscall_get_arguments()
571 - syscall_rollback() 396 - syscall_rollback()
572 - syscall_set_return_value() 397 - syscall_set_return_value()
573 - SIGSYS siginfo_t support 398 - SIGSYS siginfo_t support
574 - secure_computing is called from a 399 - secure_computing is called from a ptrace_event()-safe context
575 - secure_computing return value is c 400 - secure_computing return value is checked and a return value of -1
576 results in the system call being s 401 results in the system call being skipped immediately.
577 - seccomp syscall wired up 402 - seccomp syscall wired up
578 - if !HAVE_SPARSE_SYSCALL_NR, have S <<
579 SECCOMP_ARCH_NATIVE_NR, SECCOMP_AR <<
580 COMPAT is supported, have the SECC <<
581 <<
582 config SECCOMP <<
583 prompt "Enable seccomp to safely execu <<
584 def_bool y <<
585 depends on HAVE_ARCH_SECCOMP <<
586 help <<
587 This kernel feature is useful for nu <<
588 that may need to handle untrusted by <<
589 execution. By using pipes or other t <<
590 to the process as file descriptors s <<
591 syscalls, it's possible to isolate t <<
592 own address space using seccomp. Onc <<
593 prctl(PR_SET_SECCOMP) or the seccomp <<
594 disabled and the task is only allowe <<
595 syscalls defined by each seccomp mod <<
596 <<
597 If unsure, say Y. <<
598 403
599 config SECCOMP_FILTER 404 config SECCOMP_FILTER
600 def_bool y 405 def_bool y
601 depends on HAVE_ARCH_SECCOMP_FILTER && 406 depends on HAVE_ARCH_SECCOMP_FILTER && SECCOMP && NET
602 help 407 help
603 Enable tasks to build secure computi 408 Enable tasks to build secure computing environments defined
604 in terms of Berkeley Packet Filter p 409 in terms of Berkeley Packet Filter programs which implement
605 task-defined system call filtering p 410 task-defined system call filtering polices.
606 411
607 See Documentation/userspace-api/secc 412 See Documentation/userspace-api/seccomp_filter.rst for details.
608 413
609 config SECCOMP_CACHE_DEBUG !! 414 preferred-plugin-hostcc := $(if-success,[ $(gcc-version) -ge 40800 ],$(HOSTCXX),$(HOSTCC))
610 bool "Show seccomp filter cache status <<
611 depends on SECCOMP_FILTER && !HAVE_SPA <<
612 depends on PROC_FS <<
613 help <<
614 This enables the /proc/pid/seccomp_c <<
615 seccomp cache data. The file format <<
616 the file requires CAP_SYS_ADMIN. <<
617 415
618 This option is for debugging only. E !! 416 config PLUGIN_HOSTCC
619 an adversary may be able to infer th !! 417 string
>> 418 default "$(shell,$(srctree)/scripts/gcc-plugin.sh "$(preferred-plugin-hostcc)" "$(HOSTCXX)" "$(CC)")"
>> 419 help
>> 420 Host compiler used to build GCC plugins. This can be $(HOSTCXX),
>> 421 $(HOSTCC), or a null string if GCC plugin is unsupported.
620 422
621 If unsure, say N. !! 423 config HAVE_GCC_PLUGINS
>> 424 bool
>> 425 help
>> 426 An arch should select this symbol if it supports building with
>> 427 GCC plugins.
>> 428
>> 429 menuconfig GCC_PLUGINS
>> 430 bool "GCC plugins"
>> 431 depends on HAVE_GCC_PLUGINS
>> 432 depends on PLUGIN_HOSTCC != ""
>> 433 help
>> 434 GCC plugins are loadable modules that provide extra features to the
>> 435 compiler. They are useful for runtime instrumentation and static analysis.
>> 436
>> 437 See Documentation/gcc-plugins.txt for details.
622 438
623 config HAVE_ARCH_STACKLEAK !! 439 config GCC_PLUGIN_CYC_COMPLEXITY
>> 440 bool "Compute the cyclomatic complexity of a function" if EXPERT
>> 441 depends on GCC_PLUGINS
>> 442 depends on !COMPILE_TEST # too noisy
>> 443 help
>> 444 The complexity M of a function's control flow graph is defined as:
>> 445 M = E - N + 2P
>> 446 where
>> 447
>> 448 E = the number of edges
>> 449 N = the number of nodes
>> 450 P = the number of connected components (exit nodes).
>> 451
>> 452 Enabling this plugin reports the complexity to stderr during the
>> 453 build. It mainly serves as a simple example of how to create a
>> 454 gcc plugin for the kernel.
>> 455
>> 456 config GCC_PLUGIN_SANCOV
624 bool 457 bool
>> 458 depends on GCC_PLUGINS
>> 459 help
>> 460 This plugin inserts a __sanitizer_cov_trace_pc() call at the start of
>> 461 basic blocks. It supports all gcc versions with plugin support (from
>> 462 gcc-4.5 on). It is based on the commit "Add fuzzing coverage support"
>> 463 by Dmitry Vyukov <dvyukov@google.com>.
>> 464
>> 465 config GCC_PLUGIN_LATENT_ENTROPY
>> 466 bool "Generate some entropy during boot and runtime"
>> 467 depends on GCC_PLUGINS
625 help 468 help
626 An architecture should select this i !! 469 By saying Y here the kernel will instrument some kernel code to
627 fills the used part of the kernel st !! 470 extract some entropy from both original and artificially created
628 value before returning from system c !! 471 program state. This will help especially embedded systems where
>> 472 there is little 'natural' source of entropy normally. The cost
>> 473 is some slowdown of the boot process (about 0.5%) and fork and
>> 474 irq processing.
>> 475
>> 476 Note that entropy extracted this way is not cryptographically
>> 477 secure!
>> 478
>> 479 This plugin was ported from grsecurity/PaX. More information at:
>> 480 * https://grsecurity.net/
>> 481 * https://pax.grsecurity.net/
>> 482
>> 483 config GCC_PLUGIN_STRUCTLEAK
>> 484 bool "Force initialization of variables containing userspace addresses"
>> 485 depends on GCC_PLUGINS
>> 486 # Currently STRUCTLEAK inserts initialization out of live scope of
>> 487 # variables from KASAN point of view. This leads to KASAN false
>> 488 # positive reports. Prohibit this combination for now.
>> 489 depends on !KASAN_EXTRA
>> 490 help
>> 491 This plugin zero-initializes any structures containing a
>> 492 __user attribute. This can prevent some classes of information
>> 493 exposures.
>> 494
>> 495 This plugin was ported from grsecurity/PaX. More information at:
>> 496 * https://grsecurity.net/
>> 497 * https://pax.grsecurity.net/
>> 498
>> 499 config GCC_PLUGIN_STRUCTLEAK_BYREF_ALL
>> 500 bool "Force initialize all struct type variables passed by reference"
>> 501 depends on GCC_PLUGIN_STRUCTLEAK
>> 502 depends on !COMPILE_TEST
>> 503 help
>> 504 Zero initialize any struct type local variable that may be passed by
>> 505 reference without having been initialized.
>> 506
>> 507 config GCC_PLUGIN_STRUCTLEAK_VERBOSE
>> 508 bool "Report forcefully initialized variables"
>> 509 depends on GCC_PLUGIN_STRUCTLEAK
>> 510 depends on !COMPILE_TEST # too noisy
>> 511 help
>> 512 This option will cause a warning to be printed each time the
>> 513 structleak plugin finds a variable it thinks needs to be
>> 514 initialized. Since not all existing initializers are detected
>> 515 by the plugin, this can produce false positive warnings.
>> 516
>> 517 config GCC_PLUGIN_RANDSTRUCT
>> 518 bool "Randomize layout of sensitive kernel structures"
>> 519 depends on GCC_PLUGINS
>> 520 select MODVERSIONS if MODULES
>> 521 help
>> 522 If you say Y here, the layouts of structures that are entirely
>> 523 function pointers (and have not been manually annotated with
>> 524 __no_randomize_layout), or structures that have been explicitly
>> 525 marked with __randomize_layout, will be randomized at compile-time.
>> 526 This can introduce the requirement of an additional information
>> 527 exposure vulnerability for exploits targeting these structure
>> 528 types.
>> 529
>> 530 Enabling this feature will introduce some performance impact,
>> 531 slightly increase memory usage, and prevent the use of forensic
>> 532 tools like Volatility against the system (unless the kernel
>> 533 source tree isn't cleaned after kernel installation).
>> 534
>> 535 The seed used for compilation is located at
>> 536 scripts/gcc-plgins/randomize_layout_seed.h. It remains after
>> 537 a make clean to allow for external modules to be compiled with
>> 538 the existing seed and will be removed by a make mrproper or
>> 539 make distclean.
>> 540
>> 541 Note that the implementation requires gcc 4.7 or newer.
>> 542
>> 543 This plugin was ported from grsecurity/PaX. More information at:
>> 544 * https://grsecurity.net/
>> 545 * https://pax.grsecurity.net/
>> 546
>> 547 config GCC_PLUGIN_RANDSTRUCT_PERFORMANCE
>> 548 bool "Use cacheline-aware structure randomization"
>> 549 depends on GCC_PLUGIN_RANDSTRUCT
>> 550 depends on !COMPILE_TEST # do not reduce test coverage
>> 551 help
>> 552 If you say Y here, the RANDSTRUCT randomization will make a
>> 553 best effort at restricting randomization to cacheline-sized
>> 554 groups of elements. It will further not randomize bitfields
>> 555 in structures. This reduces the performance hit of RANDSTRUCT
>> 556 at the cost of weakened randomization.
629 557
630 config HAVE_STACKPROTECTOR 558 config HAVE_STACKPROTECTOR
631 bool 559 bool
632 help 560 help
633 An arch should select this symbol if 561 An arch should select this symbol if:
634 - it has implemented a stack canary 562 - it has implemented a stack canary (e.g. __stack_chk_guard)
635 563
>> 564 config CC_HAS_STACKPROTECTOR_NONE
>> 565 def_bool $(cc-option,-fno-stack-protector)
>> 566
636 config STACKPROTECTOR 567 config STACKPROTECTOR
637 bool "Stack Protector buffer overflow 568 bool "Stack Protector buffer overflow detection"
638 depends on HAVE_STACKPROTECTOR 569 depends on HAVE_STACKPROTECTOR
639 depends on $(cc-option,-fstack-protect 570 depends on $(cc-option,-fstack-protector)
640 default y 571 default y
641 help 572 help
642 This option turns on the "stack-prot 573 This option turns on the "stack-protector" GCC feature. This
643 feature puts, at the beginning of fu 574 feature puts, at the beginning of functions, a canary value on
644 the stack just before the return add 575 the stack just before the return address, and validates
645 the value just before actually retur 576 the value just before actually returning. Stack based buffer
646 overflows (that need to overwrite th 577 overflows (that need to overwrite this return address) now also
647 overwrite the canary, which gets det 578 overwrite the canary, which gets detected and the attack is then
648 neutralized via a kernel panic. 579 neutralized via a kernel panic.
649 580
650 Functions will have the stack-protec 581 Functions will have the stack-protector canary logic added if they
651 have an 8-byte or larger character a 582 have an 8-byte or larger character array on the stack.
652 583
653 This feature requires gcc version 4. 584 This feature requires gcc version 4.2 or above, or a distribution
654 gcc with the feature backported ("-f 585 gcc with the feature backported ("-fstack-protector").
655 586
656 On an x86 "defconfig" build, this fe 587 On an x86 "defconfig" build, this feature adds canary checks to
657 about 3% of all kernel functions, wh 588 about 3% of all kernel functions, which increases kernel code size
658 by about 0.3%. 589 by about 0.3%.
659 590
660 config STACKPROTECTOR_STRONG 591 config STACKPROTECTOR_STRONG
661 bool "Strong Stack Protector" 592 bool "Strong Stack Protector"
662 depends on STACKPROTECTOR 593 depends on STACKPROTECTOR
663 depends on $(cc-option,-fstack-protect 594 depends on $(cc-option,-fstack-protector-strong)
664 default y 595 default y
665 help 596 help
666 Functions will have the stack-protec 597 Functions will have the stack-protector canary logic added in any
667 of the following conditions: 598 of the following conditions:
668 599
669 - local variable's address used as p 600 - local variable's address used as part of the right hand side of an
670 assignment or function argument 601 assignment or function argument
671 - local variable is an array (or uni 602 - local variable is an array (or union containing an array),
672 regardless of array type or length 603 regardless of array type or length
673 - uses register local variables 604 - uses register local variables
674 605
675 This feature requires gcc version 4. 606 This feature requires gcc version 4.9 or above, or a distribution
676 gcc with the feature backported ("-f 607 gcc with the feature backported ("-fstack-protector-strong").
677 608
678 On an x86 "defconfig" build, this fe 609 On an x86 "defconfig" build, this feature adds canary checks to
679 about 20% of all kernel functions, w 610 about 20% of all kernel functions, which increases the kernel code
680 size by about 2%. 611 size by about 2%.
681 612
682 config ARCH_SUPPORTS_SHADOW_CALL_STACK <<
683 bool <<
684 help <<
685 An architecture should select this i <<
686 Shadow Call Stack and implements run <<
687 switching. <<
688 <<
689 config SHADOW_CALL_STACK <<
690 bool "Shadow Call Stack" <<
691 depends on ARCH_SUPPORTS_SHADOW_CALL_S <<
692 depends on DYNAMIC_FTRACE_WITH_ARGS || <<
693 depends on MMU <<
694 help <<
695 This option enables the compiler's S <<
696 uses a shadow stack to protect funct <<
697 being overwritten by an attacker. Mo <<
698 in the compiler's documentation: <<
699 <<
700 - Clang: https://clang.llvm.org/docs <<
701 - GCC: https://gcc.gnu.org/onlinedoc <<
702 <<
703 Note that security guarantees in the <<
704 ones documented for user space. The <<
705 of shadow stacks in memory, which me <<
706 reading and writing arbitrary memory <<
707 and hijack control flow by modifying <<
708 <<
709 config DYNAMIC_SCS <<
710 bool <<
711 help <<
712 Set by the arch code if it relies on <<
713 shadow call stack push and pop instr <<
714 compiler. <<
715 <<
716 config LTO <<
717 bool <<
718 help <<
719 Selected if the kernel will be built <<
720 <<
721 config LTO_CLANG <<
722 bool <<
723 select LTO <<
724 help <<
725 Selected if the kernel will be built <<
726 <<
727 config ARCH_SUPPORTS_LTO_CLANG <<
728 bool <<
729 help <<
730 An architecture should select this o <<
731 - compiling with Clang, <<
732 - compiling inline assembly with Cla <<
733 - and linking with LLD. <<
734 <<
735 config ARCH_SUPPORTS_LTO_CLANG_THIN <<
736 bool <<
737 help <<
738 An architecture should select this o <<
739 ThinLTO mode. <<
740 <<
741 config HAS_LTO_CLANG <<
742 def_bool y <<
743 depends on CC_IS_CLANG && LD_IS_LLD && <<
744 depends on $(success,$(NM) --help | he <<
745 depends on $(success,$(AR) --help | he <<
746 depends on ARCH_SUPPORTS_LTO_CLANG <<
747 depends on !FTRACE_MCOUNT_USE_RECORDMC <<
748 # https://github.com/ClangBuiltLinux/l <<
749 depends on (!KASAN || KASAN_HW_TAGS || <<
750 depends on (!KCOV || CLANG_VERSION >= <<
751 depends on !GCOV_KERNEL <<
752 help <<
753 The compiler and Kconfig options sup <<
754 LTO. <<
755 <<
756 choice <<
757 prompt "Link Time Optimization (LTO)" <<
758 default LTO_NONE <<
759 help <<
760 This option enables Link Time Optimi <<
761 compiler to optimize binaries global <<
762 <<
763 If unsure, select LTO_NONE. Note tha <<
764 so it's disabled by default. <<
765 <<
766 config LTO_NONE <<
767 bool "None" <<
768 help <<
769 Build the kernel normally, without L <<
770 <<
771 config LTO_CLANG_FULL <<
772 bool "Clang Full LTO (EXPERIMENTAL)" <<
773 depends on HAS_LTO_CLANG <<
774 depends on !COMPILE_TEST <<
775 select LTO_CLANG <<
776 help <<
777 This option enables Clang's full Lin <<
778 allows the compiler to optimize the <<
779 this option, the compiler generates <<
780 object files, and the actual compila <<
781 the LTO link step, which may take se <<
782 kernel configuration. More informati <<
783 documentation: <<
784 <<
785 https://llvm.org/docs/LinkTimeOpti <<
786 <<
787 During link time, this option can us <<
788 may take much longer than the ThinLT <<
789 <<
790 config LTO_CLANG_THIN <<
791 bool "Clang ThinLTO (EXPERIMENTAL)" <<
792 depends on HAS_LTO_CLANG && ARCH_SUPPO <<
793 select LTO_CLANG <<
794 help <<
795 This option enables Clang's ThinLTO, <<
796 optimization and faster incremental <<
797 CONFIG_LTO_CLANG_FULL option. More i <<
798 from Clang's documentation: <<
799 <<
800 https://clang.llvm.org/docs/ThinLT <<
801 <<
802 If unsure, say Y. <<
803 endchoice <<
804 <<
805 config ARCH_SUPPORTS_CFI_CLANG <<
806 bool <<
807 help <<
808 An architecture should select this o <<
809 Control-Flow Integrity (CFI) checkin <<
810 <<
811 config ARCH_USES_CFI_TRAPS <<
812 bool <<
813 <<
814 config CFI_CLANG <<
815 bool "Use Clang's Control Flow Integri <<
816 depends on ARCH_SUPPORTS_CFI_CLANG <<
817 depends on $(cc-option,-fsanitize=kcfi <<
818 help <<
819 This option enables Clang's forward- <<
820 (CFI) checking, where the compiler i <<
821 indirect function call to ensure the <<
822 the correct static type. This restri <<
823 makes it more difficult for an attac <<
824 the modification of stored function <<
825 found from Clang's documentation: <<
826 <<
827 https://clang.llvm.org/docs/Contro <<
828 <<
829 config CFI_PERMISSIVE <<
830 bool "Use CFI in permissive mode" <<
831 depends on CFI_CLANG <<
832 help <<
833 When selected, Control Flow Integrit <<
834 warning instead of a kernel panic. T <<
835 for finding indirect call type misma <<
836 <<
837 If unsure, say N. <<
838 <<
839 config HAVE_ARCH_WITHIN_STACK_FRAMES 613 config HAVE_ARCH_WITHIN_STACK_FRAMES
840 bool 614 bool
841 help 615 help
842 An architecture should select this i 616 An architecture should select this if it can walk the kernel stack
843 frames to determine if an object is 617 frames to determine if an object is part of either the arguments
844 or local variables (i.e. that it exc 618 or local variables (i.e. that it excludes saved return addresses,
845 and similar) by implementing an inli 619 and similar) by implementing an inline arch_within_stack_frames(),
846 which is used by CONFIG_HARDENED_USE 620 which is used by CONFIG_HARDENED_USERCOPY.
847 621
848 config HAVE_CONTEXT_TRACKING_USER !! 622 config HAVE_CONTEXT_TRACKING
849 bool 623 bool
850 help 624 help
851 Provide kernel/user boundaries probe 625 Provide kernel/user boundaries probes necessary for subsystems
852 that need it, such as userspace RCU 626 that need it, such as userspace RCU extended quiescent state.
853 Syscalls need to be wrapped inside u !! 627 Syscalls need to be wrapped inside user_exit()-user_enter() through
854 optimized behind static key or throu !! 628 the slow path using TIF_NOHZ flag. Exceptions handlers must be
855 flag. Exceptions handlers must be wr !! 629 wrapped as well. Irqs are already protected inside
856 protected inside ct_irq_enter/ct_irq !! 630 rcu_irq_enter/rcu_irq_exit() but preemption or signal handling on
857 handling on irq exit still need to b !! 631 irq exit still need to be protected.
858 <<
859 config HAVE_CONTEXT_TRACKING_USER_OFFSTACK <<
860 bool <<
861 help <<
862 Architecture neither relies on excep <<
863 nor on schedule_user(). Also preempt <<
864 preempt_schedule_irq() can't be call <<
865 while context tracking is CONTEXT_US <<
866 entry implementation where the follo <<
867 critical entry code, ie: before user <<
868 <<
869 - Critical entry code isn't preempti <<
870 not interruptible). <<
871 - No use of RCU read side critical s <<
872 got called. <<
873 - No use of instrumentation, unless <<
874 called. <<
875 <<
876 config HAVE_TIF_NOHZ <<
877 bool <<
878 help <<
879 Arch relies on TIF_NOHZ and syscall <<
880 tracking calls to user_enter()/user_ <<
881 632
882 config HAVE_VIRT_CPU_ACCOUNTING 633 config HAVE_VIRT_CPU_ACCOUNTING
883 bool 634 bool
884 635
885 config HAVE_VIRT_CPU_ACCOUNTING_IDLE <<
886 bool <<
887 help <<
888 Architecture has its own way to acco <<
889 doesn't implement vtime_account_idle <<
890 <<
891 config ARCH_HAS_SCALED_CPUTIME 636 config ARCH_HAS_SCALED_CPUTIME
892 bool 637 bool
893 638
894 config HAVE_VIRT_CPU_ACCOUNTING_GEN 639 config HAVE_VIRT_CPU_ACCOUNTING_GEN
895 bool 640 bool
896 default y if 64BIT 641 default y if 64BIT
897 help 642 help
898 With VIRT_CPU_ACCOUNTING_GEN, cputim 643 With VIRT_CPU_ACCOUNTING_GEN, cputime_t becomes 64-bit.
899 Before enabling this option, arch co 644 Before enabling this option, arch code must be audited
900 to ensure there are no races in conc 645 to ensure there are no races in concurrent read/write of
901 cputime_t. For example, reading/writ 646 cputime_t. For example, reading/writing 64-bit cputime_t on
902 some 32-bit arches may require multi 647 some 32-bit arches may require multiple accesses, so proper
903 locking is needed to protect against 648 locking is needed to protect against concurrent accesses.
904 649
>> 650
905 config HAVE_IRQ_TIME_ACCOUNTING 651 config HAVE_IRQ_TIME_ACCOUNTING
906 bool 652 bool
907 help 653 help
908 Archs need to ensure they use a high 654 Archs need to ensure they use a high enough resolution clock to
909 support irq time accounting and then 655 support irq time accounting and then call enable_sched_clock_irqtime().
910 656
911 config HAVE_MOVE_PUD <<
912 bool <<
913 help <<
914 Architectures that select this are a <<
915 PUD level. If there are only 3 page <<
916 happens at the PGD level. <<
917 <<
918 config HAVE_MOVE_PMD <<
919 bool <<
920 help <<
921 Archs that select this are able to m <<
922 <<
923 config HAVE_ARCH_TRANSPARENT_HUGEPAGE 657 config HAVE_ARCH_TRANSPARENT_HUGEPAGE
924 bool 658 bool
925 659
926 config HAVE_ARCH_TRANSPARENT_HUGEPAGE_PUD 660 config HAVE_ARCH_TRANSPARENT_HUGEPAGE_PUD
927 bool 661 bool
928 662
929 config HAVE_ARCH_HUGE_VMAP 663 config HAVE_ARCH_HUGE_VMAP
930 bool 664 bool
931 665
932 # <<
933 # Archs that select this would be capable of <<
934 # arch_vmap_pmd_supported() returns true). Th <<
935 # must be used to enable allocations to use h <<
936 # <<
937 config HAVE_ARCH_HUGE_VMALLOC <<
938 depends on HAVE_ARCH_HUGE_VMAP <<
939 bool <<
940 <<
941 config ARCH_WANT_HUGE_PMD_SHARE <<
942 bool <<
943 <<
944 # Archs that want to use pmd_mkwrite on kernel <<
945 # if there are no userspace memory management <<
946 config ARCH_WANT_KERNEL_PMD_MKWRITE <<
947 bool <<
948 <<
949 config ARCH_WANT_PMD_MKWRITE <<
950 def_bool TRANSPARENT_HUGEPAGE || ARCH_ <<
951 <<
952 config HAVE_ARCH_SOFT_DIRTY 666 config HAVE_ARCH_SOFT_DIRTY
953 bool 667 bool
954 668
955 config HAVE_MOD_ARCH_SPECIFIC 669 config HAVE_MOD_ARCH_SPECIFIC
956 bool 670 bool
957 help 671 help
958 The arch uses struct mod_arch_specif 672 The arch uses struct mod_arch_specific to store data. Many arches
959 just need a simple module loader wit 673 just need a simple module loader without arch specific data - those
960 should not enable this. 674 should not enable this.
961 675
962 config MODULES_USE_ELF_RELA 676 config MODULES_USE_ELF_RELA
963 bool 677 bool
964 help 678 help
965 Modules only use ELF RELA relocation 679 Modules only use ELF RELA relocations. Modules with ELF REL
966 relocations will give an error. 680 relocations will give an error.
967 681
968 config MODULES_USE_ELF_REL 682 config MODULES_USE_ELF_REL
969 bool 683 bool
970 help 684 help
971 Modules only use ELF REL relocations 685 Modules only use ELF REL relocations. Modules with ELF RELA
972 relocations will give an error. 686 relocations will give an error.
973 687
974 config ARCH_WANTS_MODULES_DATA_IN_VMALLOC <<
975 bool <<
976 help <<
977 For architectures like powerpc/32 wh <<
978 allocation and need to allocate modu <<
979 <<
980 config ARCH_WANTS_EXECMEM_LATE <<
981 bool <<
982 help <<
983 For architectures that do not alloca <<
984 boot, but rather require its initial <<
985 enough entropy for module space rand <<
986 arm64. <<
987 <<
988 config HAVE_IRQ_EXIT_ON_IRQ_STACK 688 config HAVE_IRQ_EXIT_ON_IRQ_STACK
989 bool 689 bool
990 help 690 help
991 Architecture doesn't only execute th 691 Architecture doesn't only execute the irq handler on the irq stack
992 but also irq_exit(). This way we can 692 but also irq_exit(). This way we can process softirqs on this irq
993 stack instead of switching to a new 693 stack instead of switching to a new one when we call __do_softirq()
994 in the end of an hardirq. 694 in the end of an hardirq.
995 This spares a stack switch and impro 695 This spares a stack switch and improves cache usage on softirq
996 processing. 696 processing.
997 697
998 config HAVE_SOFTIRQ_ON_OWN_STACK <<
999 bool <<
1000 help <<
1001 Architecture provides a function to <<
1002 separate stack. <<
1003 <<
1004 config SOFTIRQ_ON_OWN_STACK <<
1005 def_bool HAVE_SOFTIRQ_ON_OWN_STACK && <<
1006 <<
1007 config ALTERNATE_USER_ADDRESS_SPACE <<
1008 bool <<
1009 help <<
1010 Architectures set this when the CPU <<
1011 spaces for kernel and user space po <<
1012 access_ok() check on a __user point <<
1013 <<
1014 config PGTABLE_LEVELS 698 config PGTABLE_LEVELS
1015 int 699 int
1016 default 2 700 default 2
1017 701
1018 config ARCH_HAS_ELF_RANDOMIZE 702 config ARCH_HAS_ELF_RANDOMIZE
1019 bool 703 bool
1020 help 704 help
1021 An architecture supports choosing r 705 An architecture supports choosing randomized locations for
1022 stack, mmap, brk, and ET_DYN. Defin 706 stack, mmap, brk, and ET_DYN. Defined functions:
1023 - arch_mmap_rnd() 707 - arch_mmap_rnd()
1024 - arch_randomize_brk() 708 - arch_randomize_brk()
1025 709
1026 config HAVE_ARCH_MMAP_RND_BITS 710 config HAVE_ARCH_MMAP_RND_BITS
1027 bool 711 bool
1028 help 712 help
1029 An arch should select this symbol i 713 An arch should select this symbol if it supports setting a variable
1030 number of bits for use in establish 714 number of bits for use in establishing the base address for mmap
1031 allocations, has MMU enabled and pr 715 allocations, has MMU enabled and provides values for both:
1032 - ARCH_MMAP_RND_BITS_MIN 716 - ARCH_MMAP_RND_BITS_MIN
1033 - ARCH_MMAP_RND_BITS_MAX 717 - ARCH_MMAP_RND_BITS_MAX
1034 718
1035 config HAVE_EXIT_THREAD 719 config HAVE_EXIT_THREAD
1036 bool 720 bool
1037 help 721 help
1038 An architecture implements exit_thr 722 An architecture implements exit_thread.
1039 723
1040 config ARCH_MMAP_RND_BITS_MIN 724 config ARCH_MMAP_RND_BITS_MIN
1041 int 725 int
1042 726
1043 config ARCH_MMAP_RND_BITS_MAX 727 config ARCH_MMAP_RND_BITS_MAX
1044 int 728 int
1045 729
1046 config ARCH_MMAP_RND_BITS_DEFAULT 730 config ARCH_MMAP_RND_BITS_DEFAULT
1047 int 731 int
1048 732
1049 config ARCH_MMAP_RND_BITS 733 config ARCH_MMAP_RND_BITS
1050 int "Number of bits to use for ASLR o 734 int "Number of bits to use for ASLR of mmap base address" if EXPERT
1051 range ARCH_MMAP_RND_BITS_MIN ARCH_MMA 735 range ARCH_MMAP_RND_BITS_MIN ARCH_MMAP_RND_BITS_MAX
1052 default ARCH_MMAP_RND_BITS_DEFAULT if 736 default ARCH_MMAP_RND_BITS_DEFAULT if ARCH_MMAP_RND_BITS_DEFAULT
1053 default ARCH_MMAP_RND_BITS_MIN 737 default ARCH_MMAP_RND_BITS_MIN
1054 depends on HAVE_ARCH_MMAP_RND_BITS 738 depends on HAVE_ARCH_MMAP_RND_BITS
1055 help 739 help
1056 This value can be used to select th 740 This value can be used to select the number of bits to use to
1057 determine the random offset to the 741 determine the random offset to the base address of vma regions
1058 resulting from mmap allocations. Th 742 resulting from mmap allocations. This value will be bounded
1059 by the architecture's minimum and m 743 by the architecture's minimum and maximum supported values.
1060 744
1061 This value can be changed after boo 745 This value can be changed after boot using the
1062 /proc/sys/vm/mmap_rnd_bits tunable 746 /proc/sys/vm/mmap_rnd_bits tunable
1063 747
1064 config HAVE_ARCH_MMAP_RND_COMPAT_BITS 748 config HAVE_ARCH_MMAP_RND_COMPAT_BITS
1065 bool 749 bool
1066 help 750 help
1067 An arch should select this symbol i 751 An arch should select this symbol if it supports running applications
1068 in compatibility mode, supports set 752 in compatibility mode, supports setting a variable number of bits for
1069 use in establishing the base addres 753 use in establishing the base address for mmap allocations, has MMU
1070 enabled and provides values for bot 754 enabled and provides values for both:
1071 - ARCH_MMAP_RND_COMPAT_BITS_MIN 755 - ARCH_MMAP_RND_COMPAT_BITS_MIN
1072 - ARCH_MMAP_RND_COMPAT_BITS_MAX 756 - ARCH_MMAP_RND_COMPAT_BITS_MAX
1073 757
1074 config ARCH_MMAP_RND_COMPAT_BITS_MIN 758 config ARCH_MMAP_RND_COMPAT_BITS_MIN
1075 int 759 int
1076 760
1077 config ARCH_MMAP_RND_COMPAT_BITS_MAX 761 config ARCH_MMAP_RND_COMPAT_BITS_MAX
1078 int 762 int
1079 763
1080 config ARCH_MMAP_RND_COMPAT_BITS_DEFAULT 764 config ARCH_MMAP_RND_COMPAT_BITS_DEFAULT
1081 int 765 int
1082 766
1083 config ARCH_MMAP_RND_COMPAT_BITS 767 config ARCH_MMAP_RND_COMPAT_BITS
1084 int "Number of bits to use for ASLR o 768 int "Number of bits to use for ASLR of mmap base address for compatible applications" if EXPERT
1085 range ARCH_MMAP_RND_COMPAT_BITS_MIN A 769 range ARCH_MMAP_RND_COMPAT_BITS_MIN ARCH_MMAP_RND_COMPAT_BITS_MAX
1086 default ARCH_MMAP_RND_COMPAT_BITS_DEF 770 default ARCH_MMAP_RND_COMPAT_BITS_DEFAULT if ARCH_MMAP_RND_COMPAT_BITS_DEFAULT
1087 default ARCH_MMAP_RND_COMPAT_BITS_MIN 771 default ARCH_MMAP_RND_COMPAT_BITS_MIN
1088 depends on HAVE_ARCH_MMAP_RND_COMPAT_ 772 depends on HAVE_ARCH_MMAP_RND_COMPAT_BITS
1089 help 773 help
1090 This value can be used to select th 774 This value can be used to select the number of bits to use to
1091 determine the random offset to the 775 determine the random offset to the base address of vma regions
1092 resulting from mmap allocations for 776 resulting from mmap allocations for compatible applications This
1093 value will be bounded by the archit 777 value will be bounded by the architecture's minimum and maximum
1094 supported values. 778 supported values.
1095 779
1096 This value can be changed after boo 780 This value can be changed after boot using the
1097 /proc/sys/vm/mmap_rnd_compat_bits t 781 /proc/sys/vm/mmap_rnd_compat_bits tunable
1098 782
1099 config HAVE_ARCH_COMPAT_MMAP_BASES 783 config HAVE_ARCH_COMPAT_MMAP_BASES
1100 bool 784 bool
1101 help 785 help
1102 This allows 64bit applications to i 786 This allows 64bit applications to invoke 32-bit mmap() syscall
1103 and vice-versa 32-bit applications 787 and vice-versa 32-bit applications to call 64-bit mmap().
1104 Required for applications doing dif 788 Required for applications doing different bitness syscalls.
1105 789
1106 config HAVE_PAGE_SIZE_4KB !! 790 config HAVE_COPY_THREAD_TLS
1107 bool <<
1108 <<
1109 config HAVE_PAGE_SIZE_8KB <<
1110 bool <<
1111 <<
1112 config HAVE_PAGE_SIZE_16KB <<
1113 bool <<
1114 <<
1115 config HAVE_PAGE_SIZE_32KB <<
1116 bool <<
1117 <<
1118 config HAVE_PAGE_SIZE_64KB <<
1119 bool <<
1120 <<
1121 config HAVE_PAGE_SIZE_256KB <<
1122 bool 791 bool
1123 <<
1124 choice <<
1125 prompt "MMU page size" <<
1126 <<
1127 config PAGE_SIZE_4KB <<
1128 bool "4KiB pages" <<
1129 depends on HAVE_PAGE_SIZE_4KB <<
1130 help <<
1131 This option select the standard 4Ki <<
1132 available option on many architectu <<
1133 minimize memory consumption and is <<
1134 memory systems. <<
1135 Some software that is written for x <<
1136 assumptions about the page size and <<
1137 <<
1138 config PAGE_SIZE_8KB <<
1139 bool "8KiB pages" <<
1140 depends on HAVE_PAGE_SIZE_8KB <<
1141 help <<
1142 This option is the only supported p <<
1143 processors, and can be slightly fas <<
1144 <<
1145 config PAGE_SIZE_16KB <<
1146 bool "16KiB pages" <<
1147 depends on HAVE_PAGE_SIZE_16KB <<
1148 help <<
1149 This option is usually a good compr <<
1150 consumption and performance for typ <<
1151 workloads, often saving a level of <<
1152 to 4KB pages as well as reducing TL <<
1153 per-page operations in the kernel a <<
1154 page cache. <<
1155 <<
1156 config PAGE_SIZE_32KB <<
1157 bool "32KiB pages" <<
1158 depends on HAVE_PAGE_SIZE_32KB <<
1159 help <<
1160 Using 32KiB page size will result i <<
1161 kernel at the price of higher memor <<
1162 16KiB pages. This option is availa <<
1163 Note that you will need a suitable <<
1164 support this. <<
1165 <<
1166 config PAGE_SIZE_64KB <<
1167 bool "64KiB pages" <<
1168 depends on HAVE_PAGE_SIZE_64KB <<
1169 help <<
1170 Using 64KiB page size will result i <<
1171 kernel at the price of much higher <<
1172 4KiB or 16KiB pages. <<
1173 This is not suitable for general-pu <<
1174 better performance may be worth the <<
1175 supercomputing or database applicat <<
1176 large in-memory data rather than sm <<
1177 <<
1178 config PAGE_SIZE_256KB <<
1179 bool "256KiB pages" <<
1180 depends on HAVE_PAGE_SIZE_256KB <<
1181 help 792 help
1182 256KiB pages have little practical !! 793 Architecture provides copy_thread_tls to accept tls argument via
1183 memory usage. The kernel will only !! 794 normal C parameter passing, rather than extracting the syscall
1184 that have been compiled with '-zmax !! 795 argument from pt_regs.
1185 (the default is 64KiB or 4KiB on mo <<
1186 <<
1187 endchoice <<
1188 <<
1189 config PAGE_SIZE_LESS_THAN_64KB <<
1190 def_bool y <<
1191 depends on !PAGE_SIZE_64KB <<
1192 depends on PAGE_SIZE_LESS_THAN_256KB <<
1193 <<
1194 config PAGE_SIZE_LESS_THAN_256KB <<
1195 def_bool y <<
1196 depends on !PAGE_SIZE_256KB <<
1197 <<
1198 config PAGE_SHIFT <<
1199 int <<
1200 default 12 if PAGE_SIZE_4KB <<
1201 default 13 if PAGE_SIZE_8KB <<
1202 default 14 if PAGE_SIZE_16KB <<
1203 default 15 if PAGE_SIZE_32KB <<
1204 default 16 if PAGE_SIZE_64KB <<
1205 default 18 if PAGE_SIZE_256KB <<
1206 <<
1207 # This allows to use a set of generic functio <<
1208 # address by giving priority to top-down sche <<
1209 # is not in legacy mode (compat task, unlimit <<
1210 # sysctl_legacy_va_layout). <<
1211 # Architecture that selects this option can p <<
1212 # - STACK_RND_MASK <<
1213 config ARCH_WANT_DEFAULT_TOPDOWN_MMAP_LAYOUT <<
1214 bool <<
1215 depends on MMU <<
1216 select ARCH_HAS_ELF_RANDOMIZE <<
1217 <<
1218 config HAVE_OBJTOOL <<
1219 bool <<
1220 <<
1221 config HAVE_JUMP_LABEL_HACK <<
1222 bool <<
1223 <<
1224 config HAVE_NOINSTR_HACK <<
1225 bool <<
1226 <<
1227 config HAVE_NOINSTR_VALIDATION <<
1228 bool <<
1229 <<
1230 config HAVE_UACCESS_VALIDATION <<
1231 bool <<
1232 select OBJTOOL <<
1233 796
1234 config HAVE_STACK_VALIDATION 797 config HAVE_STACK_VALIDATION
1235 bool 798 bool
1236 help 799 help
1237 Architecture supports objtool compi !! 800 Architecture supports the 'objtool check' host tool command, which
1238 validation. !! 801 performs compile-time stack metadata validation.
1239 802
1240 config HAVE_RELIABLE_STACKTRACE 803 config HAVE_RELIABLE_STACKTRACE
1241 bool 804 bool
1242 help 805 help
1243 Architecture has either save_stack_ !! 806 Architecture has a save_stack_trace_tsk_reliable() function which
1244 arch_stack_walk_reliable() function !! 807 only returns a stack trace if it can guarantee the trace is reliable.
1245 if it can guarantee the trace is re <<
1246 808
1247 config HAVE_ARCH_HASH 809 config HAVE_ARCH_HASH
1248 bool 810 bool
1249 default n 811 default n
1250 help 812 help
1251 If this is set, the architecture pr 813 If this is set, the architecture provides an <asm/hash.h>
1252 file which provides platform-specif 814 file which provides platform-specific implementations of some
1253 functions in <linux/hash.h> or fs/n 815 functions in <linux/hash.h> or fs/namei.c.
1254 816
1255 config HAVE_ARCH_NVRAM_OPS <<
1256 bool <<
1257 <<
1258 config ISA_BUS_API 817 config ISA_BUS_API
1259 def_bool ISA 818 def_bool ISA
1260 819
1261 # 820 #
1262 # ABI hall of shame 821 # ABI hall of shame
1263 # 822 #
1264 config CLONE_BACKWARDS 823 config CLONE_BACKWARDS
1265 bool 824 bool
1266 help 825 help
1267 Architecture has tls passed as the 826 Architecture has tls passed as the 4th argument of clone(2),
1268 not the 5th one. 827 not the 5th one.
1269 828
1270 config CLONE_BACKWARDS2 829 config CLONE_BACKWARDS2
1271 bool 830 bool
1272 help 831 help
1273 Architecture has the first two argu 832 Architecture has the first two arguments of clone(2) swapped.
1274 833
1275 config CLONE_BACKWARDS3 834 config CLONE_BACKWARDS3
1276 bool 835 bool
1277 help 836 help
1278 Architecture has tls passed as the 837 Architecture has tls passed as the 3rd argument of clone(2),
1279 not the 5th one. 838 not the 5th one.
1280 839
1281 config ODD_RT_SIGACTION 840 config ODD_RT_SIGACTION
1282 bool 841 bool
1283 help 842 help
1284 Architecture has unusual rt_sigacti 843 Architecture has unusual rt_sigaction(2) arguments
1285 844
1286 config OLD_SIGSUSPEND 845 config OLD_SIGSUSPEND
1287 bool 846 bool
1288 help 847 help
1289 Architecture has old sigsuspend(2) 848 Architecture has old sigsuspend(2) syscall, of one-argument variety
1290 849
1291 config OLD_SIGSUSPEND3 850 config OLD_SIGSUSPEND3
1292 bool 851 bool
1293 help 852 help
1294 Even weirder antique ABI - three-ar 853 Even weirder antique ABI - three-argument sigsuspend(2)
1295 854
1296 config OLD_SIGACTION 855 config OLD_SIGACTION
1297 bool 856 bool
1298 help 857 help
1299 Architecture has old sigaction(2) s 858 Architecture has old sigaction(2) syscall. Nope, not the same
1300 as OLD_SIGSUSPEND | OLD_SIGSUSPEND3 859 as OLD_SIGSUSPEND | OLD_SIGSUSPEND3 - alpha has sigsuspend(2),
1301 but fairly different variant of sig 860 but fairly different variant of sigaction(2), thanks to OSF/1
1302 compatibility... 861 compatibility...
1303 862
1304 config COMPAT_OLD_SIGACTION 863 config COMPAT_OLD_SIGACTION
1305 bool 864 bool
1306 865
>> 866 config 64BIT_TIME
>> 867 def_bool ARCH_HAS_64BIT_TIME
>> 868 help
>> 869 This should be selected by all architectures that need to support
>> 870 new system calls with a 64-bit time_t. This is relevant on all 32-bit
>> 871 architectures, and 64-bit architectures as part of compat syscall
>> 872 handling.
>> 873
1307 config COMPAT_32BIT_TIME 874 config COMPAT_32BIT_TIME
1308 bool "Provide system calls for 32-bit !! 875 def_bool (!64BIT && 64BIT_TIME) || COMPAT
1309 default !64BIT || COMPAT <<
1310 help 876 help
1311 This enables 32 bit time_t support 877 This enables 32 bit time_t support in addition to 64 bit time_t support.
1312 This is relevant on all 32-bit arch 878 This is relevant on all 32-bit architectures, and 64-bit architectures
1313 as part of compat syscall handling. 879 as part of compat syscall handling.
1314 880
1315 config ARCH_NO_PREEMPT !! 881 config ARCH_NO_COHERENT_DMA_MMAP
1316 bool <<
1317 <<
1318 config ARCH_SUPPORTS_RT <<
1319 bool 882 bool
1320 883
1321 config CPU_NO_EFFICIENT_FFS 884 config CPU_NO_EFFICIENT_FFS
1322 def_bool n 885 def_bool n
1323 886
1324 config HAVE_ARCH_VMAP_STACK 887 config HAVE_ARCH_VMAP_STACK
1325 def_bool n 888 def_bool n
1326 help 889 help
1327 An arch should select this symbol i 890 An arch should select this symbol if it can support kernel stacks
1328 in vmalloc space. This means: 891 in vmalloc space. This means:
1329 892
1330 - vmalloc space must be large enoug 893 - vmalloc space must be large enough to hold many kernel stacks.
1331 This may rule out many 32-bit arc 894 This may rule out many 32-bit architectures.
1332 895
1333 - Stacks in vmalloc space need to w 896 - Stacks in vmalloc space need to work reliably. For example, if
1334 vmap page tables are created on d 897 vmap page tables are created on demand, either this mechanism
1335 needs to work while the stack poi 898 needs to work while the stack points to a virtual address with
1336 unpopulated page tables or arch c 899 unpopulated page tables or arch code (switch_to() and switch_mm(),
1337 most likely) needs to ensure that 900 most likely) needs to ensure that the stack's page table entries
1338 are populated before running on a 901 are populated before running on a possibly unpopulated stack.
1339 902
1340 - If the stack overflows into a gua 903 - If the stack overflows into a guard page, something reasonable
1341 should happen. The definition of 904 should happen. The definition of "reasonable" is flexible, but
1342 instantly rebooting without loggi 905 instantly rebooting without logging anything would be unfriendly.
1343 906
1344 config VMAP_STACK 907 config VMAP_STACK
1345 default y 908 default y
1346 bool "Use a virtually-mapped stack" 909 bool "Use a virtually-mapped stack"
1347 depends on HAVE_ARCH_VMAP_STACK !! 910 depends on HAVE_ARCH_VMAP_STACK && !KASAN
1348 depends on !KASAN || KASAN_HW_TAGS || !! 911 ---help---
1349 help <<
1350 Enable this if you want the use vir 912 Enable this if you want the use virtually-mapped kernel stacks
1351 with guard pages. This causes kern 913 with guard pages. This causes kernel stack overflows to be
1352 caught immediately rather than caus 914 caught immediately rather than causing difficult-to-diagnose
1353 corruption. 915 corruption.
1354 916
1355 To use this with software KASAN mod !! 917 This is presently incompatible with KASAN because KASAN expects
1356 backing virtual mappings with real !! 918 the stack to map directly to the KASAN shadow map using a formula
1357 must be enabled. !! 919 that is incorrect if the stack is in vmalloc space.
1358 <<
1359 config HAVE_ARCH_RANDOMIZE_KSTACK_OFFSET <<
1360 def_bool n <<
1361 help <<
1362 An arch should select this symbol i <<
1363 offset randomization with calls to <<
1364 during syscall entry and choose_ran <<
1365 syscall exit. Careful removal of -f <<
1366 -fstack-protector should also be ap <<
1367 closely examined, as the artificial <<
1368 to the compiler, so it will attempt <<
1369 of the static branch state. <<
1370 <<
1371 config RANDOMIZE_KSTACK_OFFSET <<
1372 bool "Support for randomizing kernel <<
1373 default y <<
1374 depends on HAVE_ARCH_RANDOMIZE_KSTACK <<
1375 depends on INIT_STACK_NONE || !CC_IS_ <<
1376 help <<
1377 The kernel stack offset can be rand <<
1378 roughly 5 bits of entropy, frustrat <<
1379 attacks that depend on stack addres <<
1380 cross-syscall address exposures. <<
1381 <<
1382 The feature is controlled via the " <<
1383 kernel boot param, and if turned of <<
1384 of static branches (see JUMP_LABEL) <<
1385 <<
1386 If unsure, say Y. <<
1387 <<
1388 config RANDOMIZE_KSTACK_OFFSET_DEFAULT <<
1389 bool "Default state of kernel stack o <<
1390 depends on RANDOMIZE_KSTACK_OFFSET <<
1391 help <<
1392 Kernel stack offset randomization i <<
1393 "randomize_kstack_offset=on/off", a <<
1394 boot state. <<
1395 920
1396 config ARCH_OPTIONAL_KERNEL_RWX 921 config ARCH_OPTIONAL_KERNEL_RWX
1397 def_bool n 922 def_bool n
1398 923
1399 config ARCH_OPTIONAL_KERNEL_RWX_DEFAULT 924 config ARCH_OPTIONAL_KERNEL_RWX_DEFAULT
1400 def_bool n 925 def_bool n
1401 926
1402 config ARCH_HAS_STRICT_KERNEL_RWX 927 config ARCH_HAS_STRICT_KERNEL_RWX
1403 def_bool n 928 def_bool n
1404 929
1405 config STRICT_KERNEL_RWX 930 config STRICT_KERNEL_RWX
1406 bool "Make kernel text and rodata rea 931 bool "Make kernel text and rodata read-only" if ARCH_OPTIONAL_KERNEL_RWX
1407 depends on ARCH_HAS_STRICT_KERNEL_RWX 932 depends on ARCH_HAS_STRICT_KERNEL_RWX
1408 default !ARCH_OPTIONAL_KERNEL_RWX || 933 default !ARCH_OPTIONAL_KERNEL_RWX || ARCH_OPTIONAL_KERNEL_RWX_DEFAULT
1409 help 934 help
1410 If this is set, kernel text and rod 935 If this is set, kernel text and rodata memory will be made read-only,
1411 and non-text memory will be made no 936 and non-text memory will be made non-executable. This provides
1412 protection against certain security 937 protection against certain security exploits (e.g. executing the heap
1413 or modifying text) 938 or modifying text)
1414 939
1415 These features are considered stand 940 These features are considered standard security practice these days.
1416 You should say Y here in almost all 941 You should say Y here in almost all cases.
1417 942
1418 config ARCH_HAS_STRICT_MODULE_RWX 943 config ARCH_HAS_STRICT_MODULE_RWX
1419 def_bool n 944 def_bool n
1420 945
1421 config STRICT_MODULE_RWX 946 config STRICT_MODULE_RWX
1422 bool "Set loadable kernel module data 947 bool "Set loadable kernel module data as NX and text as RO" if ARCH_OPTIONAL_KERNEL_RWX
1423 depends on ARCH_HAS_STRICT_MODULE_RWX 948 depends on ARCH_HAS_STRICT_MODULE_RWX && MODULES
1424 default !ARCH_OPTIONAL_KERNEL_RWX || 949 default !ARCH_OPTIONAL_KERNEL_RWX || ARCH_OPTIONAL_KERNEL_RWX_DEFAULT
1425 help 950 help
1426 If this is set, module text and rod 951 If this is set, module text and rodata memory will be made read-only,
1427 and non-text memory will be made no 952 and non-text memory will be made non-executable. This provides
1428 protection against certain security 953 protection against certain security exploits (e.g. writing to text)
1429 954
1430 # select if the architecture provides an asm/ 955 # select if the architecture provides an asm/dma-direct.h header
1431 config ARCH_HAS_PHYS_TO_DMA 956 config ARCH_HAS_PHYS_TO_DMA
1432 bool 957 bool
1433 958
>> 959 config ARCH_HAS_REFCOUNT
>> 960 bool
>> 961 help
>> 962 An architecture selects this when it has implemented refcount_t
>> 963 using open coded assembly primitives that provide an optimized
>> 964 refcount_t implementation, possibly at the expense of some full
>> 965 refcount state checks of CONFIG_REFCOUNT_FULL=y.
>> 966
>> 967 The refcount overflow check behavior, however, must be retained.
>> 968 Catching overflows is the primary security concern for protecting
>> 969 against bugs in reference counts.
>> 970
>> 971 config REFCOUNT_FULL
>> 972 bool "Perform full reference count validation at the expense of speed"
>> 973 help
>> 974 Enabling this switches the refcounting infrastructure from a fast
>> 975 unchecked atomic_t implementation to a fully state checked
>> 976 implementation, which can be (slightly) slower but provides protections
>> 977 against various use-after-free conditions that can be used in
>> 978 security flaw exploits.
>> 979
1434 config HAVE_ARCH_COMPILER_H 980 config HAVE_ARCH_COMPILER_H
1435 bool 981 bool
1436 help 982 help
1437 An architecture can select this if 983 An architecture can select this if it provides an
1438 asm/compiler.h header that should b 984 asm/compiler.h header that should be included after
1439 linux/compiler-*.h in order to over 985 linux/compiler-*.h in order to override macro definitions that those
1440 headers generally provide. 986 headers generally provide.
1441 987
1442 config HAVE_ARCH_PREL32_RELOCATIONS <<
1443 bool <<
1444 help <<
1445 May be selected by an architecture <<
1446 32-bit relocations, both in the too <<
1447 in which case relative references c <<
1448 for PCI fixup, initcalls etc which <<
1449 architectures, and don't require ru <<
1450 kernels. <<
1451 <<
1452 config ARCH_USE_MEMREMAP_PROT <<
1453 bool <<
1454 <<
1455 config LOCK_EVENT_COUNTS <<
1456 bool "Locking event counts collection <<
1457 depends on DEBUG_FS <<
1458 help <<
1459 Enable light-weight counting of var <<
1460 in the system with minimal performa <<
1461 the chance of application behavior <<
1462 differences. The counts are reporte <<
1463 <<
1464 # Select if the architecture has support for <<
1465 config ARCH_HAS_RELR <<
1466 bool <<
1467 <<
1468 config RELR <<
1469 bool "Use RELR relocation packing" <<
1470 depends on ARCH_HAS_RELR && TOOLS_SUP <<
1471 default y <<
1472 help <<
1473 Store the kernel's dynamic relocati <<
1474 format. Requires a compatible linke <<
1475 well as compatible NM and OBJCOPY u <<
1476 are compatible). <<
1477 <<
1478 config ARCH_HAS_MEM_ENCRYPT <<
1479 bool <<
1480 <<
1481 config ARCH_HAS_CC_PLATFORM <<
1482 bool <<
1483 <<
1484 config HAVE_SPARSE_SYSCALL_NR <<
1485 bool <<
1486 help <<
1487 An architecture should select this <<
1488 to save space. For example, MIPS ar <<
1489 entries at 4000, 5000 and 6000 loca <<
1490 related optimizations for a given a <<
1491 <<
1492 config ARCH_HAS_VDSO_DATA <<
1493 bool <<
1494 <<
1495 config HAVE_STATIC_CALL <<
1496 bool <<
1497 <<
1498 config HAVE_STATIC_CALL_INLINE <<
1499 bool <<
1500 depends on HAVE_STATIC_CALL <<
1501 select OBJTOOL <<
1502 <<
1503 config HAVE_PREEMPT_DYNAMIC <<
1504 bool <<
1505 <<
1506 config HAVE_PREEMPT_DYNAMIC_CALL <<
1507 bool <<
1508 depends on HAVE_STATIC_CALL <<
1509 select HAVE_PREEMPT_DYNAMIC <<
1510 help <<
1511 An architecture should select this <<
1512 model being selected at boot time u <<
1513 <<
1514 Where an architecture selects HAVE_ <<
1515 preemption function will be patched <<
1516 <<
1517 Where an architecture does not sele <<
1518 call to a preemption function will <<
1519 trampoline will be patched. <<
1520 <<
1521 It is strongly advised to support i <<
1522 overhead. <<
1523 <<
1524 config HAVE_PREEMPT_DYNAMIC_KEY <<
1525 bool <<
1526 depends on HAVE_ARCH_JUMP_LABEL <<
1527 select HAVE_PREEMPT_DYNAMIC <<
1528 help <<
1529 An architecture should select this <<
1530 model being selected at boot time u <<
1531 <<
1532 Each preemption function will be gi <<
1533 static key. This should have slight <<
1534 static calls, as this effectively i <<
1535 start of its callee. This may avoid <<
1536 integrate better with CFI schemes. <<
1537 <<
1538 This will have greater overhead tha <<
1539 the call to the preemption function <<
1540 <<
1541 config ARCH_WANT_LD_ORPHAN_WARN <<
1542 bool <<
1543 help <<
1544 An arch should select this symbol o <<
1545 included, size-asserted, or discard <<
1546 important because we never want exp <<
1547 by the linker, since the locations <<
1548 versions. <<
1549 <<
1550 config HAVE_ARCH_PFN_VALID <<
1551 bool <<
1552 <<
1553 config ARCH_SUPPORTS_DEBUG_PAGEALLOC <<
1554 bool <<
1555 <<
1556 config ARCH_SUPPORTS_PAGE_TABLE_CHECK <<
1557 bool <<
1558 <<
1559 config ARCH_SPLIT_ARG64 <<
1560 bool <<
1561 help <<
1562 If a 32-bit architecture requires 6 <<
1563 pairs of 32-bit arguments, select t <<
1564 <<
1565 config ARCH_HAS_ELFCORE_COMPAT <<
1566 bool <<
1567 <<
1568 config ARCH_HAS_PARANOID_L1D_FLUSH <<
1569 bool <<
1570 <<
1571 config ARCH_HAVE_TRACE_MMIO_ACCESS <<
1572 bool <<
1573 <<
1574 config DYNAMIC_SIGFRAME <<
1575 bool <<
1576 <<
1577 # Select, if arch has a named attribute group <<
1578 config HAVE_ARCH_NODE_DEV_GROUP <<
1579 bool <<
1580 <<
1581 config ARCH_HAS_HW_PTE_YOUNG <<
1582 bool <<
1583 help <<
1584 Architectures that select this opti <<
1585 accessed bit in PTE entries when us <<
1586 translations. Architectures that re <<
1587 this option and override arch_has_h <<
1588 <<
1589 config ARCH_HAS_NONLEAF_PMD_YOUNG <<
1590 bool <<
1591 help <<
1592 Architectures that select this opti <<
1593 accessed bit in non-leaf PMD entrie <<
1594 address translations. Page table wa <<
1595 may use this capability to reduce t <<
1596 <<
1597 config ARCH_HAS_KERNEL_FPU_SUPPORT <<
1598 bool <<
1599 help <<
1600 Architectures that select this opti <<
1601 the kernel, as described in Documen <<
1602 <<
1603 source "kernel/gcov/Kconfig" 988 source "kernel/gcov/Kconfig"
1604 <<
1605 source "scripts/gcc-plugins/Kconfig" <<
1606 <<
1607 config FUNCTION_ALIGNMENT_4B <<
1608 bool <<
1609 <<
1610 config FUNCTION_ALIGNMENT_8B <<
1611 bool <<
1612 <<
1613 config FUNCTION_ALIGNMENT_16B <<
1614 bool <<
1615 <<
1616 config FUNCTION_ALIGNMENT_32B <<
1617 bool <<
1618 <<
1619 config FUNCTION_ALIGNMENT_64B <<
1620 bool <<
1621 <<
1622 config FUNCTION_ALIGNMENT <<
1623 int <<
1624 default 64 if FUNCTION_ALIGNMENT_64B <<
1625 default 32 if FUNCTION_ALIGNMENT_32B <<
1626 default 16 if FUNCTION_ALIGNMENT_16B <<
1627 default 8 if FUNCTION_ALIGNMENT_8B <<
1628 default 4 if FUNCTION_ALIGNMENT_4B <<
1629 default 0 <<
1630 <<
1631 config CC_HAS_MIN_FUNCTION_ALIGNMENT <<
1632 # Detect availability of the GCC opti <<
1633 # guarantees minimal alignment for al <<
1634 # -falign-functions which the compile <<
1635 def_bool $(cc-option, -fmin-function- <<
1636 <<
1637 config CC_HAS_SANE_FUNCTION_ALIGNMENT <<
1638 # Set if the guaranteed alignment wit <<
1639 # available or extra care is required <<
1640 # strict alignment always, even with <<
1641 def_bool CC_HAS_MIN_FUNCTION_ALIGNMEN <<
1642 <<
1643 config ARCH_NEED_CMPXCHG_1_EMU <<
1644 bool <<
1645 <<
1646 endmenu <<
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