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 #
7 # Note: arch/$(SRCARCH)/Kconfig needs to be in 7 # Note: arch/$(SRCARCH)/Kconfig needs to be included first so that it can
8 # override the default values in this file. 8 # override the default values in this file.
9 # 9 #
10 source "arch/$(SRCARCH)/Kconfig" 10 source "arch/$(SRCARCH)/Kconfig"
11 11
12 config ARCH_CONFIGURES_CPU_MITIGATIONS <<
13 bool <<
14 <<
15 if !ARCH_CONFIGURES_CPU_MITIGATIONS <<
16 config CPU_MITIGATIONS <<
17 def_bool y <<
18 endif <<
19 <<
20 # <<
21 # Selected by architectures that need custom D <<
22 # IOMMUs not handled by dma-iommu. Drivers mu <<
23 # <<
24 config ARCH_HAS_DMA_OPS <<
25 depends on HAS_DMA <<
26 select DMA_OPS_HELPERS <<
27 bool <<
28 <<
29 menu "General architecture-dependent options" 12 menu "General architecture-dependent options"
30 13
31 config ARCH_HAS_SUBPAGE_FAULTS !! 14 config CRASH_CORE
32 bool 15 bool
33 help <<
34 Select if the architecture can check <<
35 granularity (e.g. arm64 MTE). The pr <<
36 must be implemented. <<
37 16
38 config HOTPLUG_SMT !! 17 config KEXEC_CORE
>> 18 select CRASH_CORE
39 bool 19 bool
40 20
41 config SMT_NUM_THREADS_DYNAMIC !! 21 config HAVE_IMA_KEXEC
42 bool 22 bool
43 23
44 # Selected by HOTPLUG_CORE_SYNC_DEAD or HOTPLU !! 24 config HOTPLUG_SMT
45 config HOTPLUG_CORE_SYNC <<
46 bool 25 bool
47 26
48 # Basic CPU dead synchronization selected by a !! 27 config OPROFILE
49 config HOTPLUG_CORE_SYNC_DEAD !! 28 tristate "OProfile system profiling"
50 bool !! 29 depends on PROFILING
51 select HOTPLUG_CORE_SYNC !! 30 depends on HAVE_OPROFILE
>> 31 select RING_BUFFER
>> 32 select RING_BUFFER_ALLOW_SWAP
>> 33 help
>> 34 OProfile is a profiling system capable of profiling the
>> 35 whole system, include the kernel, kernel modules, libraries,
>> 36 and applications.
52 37
53 # Full CPU synchronization with alive state se !! 38 If unsure, say N.
54 config HOTPLUG_CORE_SYNC_FULL <<
55 bool <<
56 select HOTPLUG_CORE_SYNC_DEAD if HOTPL <<
57 select HOTPLUG_CORE_SYNC <<
58 39
59 config HOTPLUG_SPLIT_STARTUP !! 40 config OPROFILE_EVENT_MULTIPLEX
60 bool !! 41 bool "OProfile multiplexing support (EXPERIMENTAL)"
61 select HOTPLUG_CORE_SYNC_FULL !! 42 default n
>> 43 depends on OPROFILE && X86
>> 44 help
>> 45 The number of hardware counters is limited. The multiplexing
>> 46 feature enables OProfile to gather more events than counters
>> 47 are provided by the hardware. This is realized by switching
>> 48 between events at a user specified time interval.
62 49
63 config HOTPLUG_PARALLEL !! 50 If unsure, say N.
64 bool <<
65 select HOTPLUG_SPLIT_STARTUP <<
66 51
67 config GENERIC_ENTRY !! 52 config HAVE_OPROFILE
68 bool 53 bool
69 54
>> 55 config OPROFILE_NMI_TIMER
>> 56 def_bool y
>> 57 depends on PERF_EVENTS && HAVE_PERF_EVENTS_NMI && !PPC64
>> 58
70 config KPROBES 59 config KPROBES
71 bool "Kprobes" 60 bool "Kprobes"
>> 61 depends on MODULES
72 depends on HAVE_KPROBES 62 depends on HAVE_KPROBES
73 select KALLSYMS 63 select KALLSYMS
74 select EXECMEM <<
75 select NEED_TASKS_RCU <<
76 help 64 help
77 Kprobes allows you to trap at almost 65 Kprobes allows you to trap at almost any kernel address and
78 execute a callback function. regist 66 execute a callback function. register_kprobe() establishes
79 a probepoint and specifies the callb 67 a probepoint and specifies the callback. Kprobes is useful
80 for kernel debugging, non-intrusive 68 for kernel debugging, non-intrusive instrumentation and testing.
81 If in doubt, say "N". 69 If in doubt, say "N".
82 70
83 config JUMP_LABEL 71 config JUMP_LABEL
84 bool "Optimize very unlikely/likely br !! 72 bool "Optimize very unlikely/likely branches"
85 depends on HAVE_ARCH_JUMP_LABEL !! 73 depends on HAVE_ARCH_JUMP_LABEL
86 select OBJTOOL if HAVE_JUMP_LABEL_HACK !! 74 depends on CC_HAS_ASM_GOTO
87 help !! 75 help
88 This option enables a transparent br !! 76 This option enables a transparent branch optimization that
89 makes certain almost-always-true or !! 77 makes certain almost-always-true or almost-always-false branch
90 conditions even cheaper to execute w !! 78 conditions even cheaper to execute within the kernel.
91 !! 79
92 Certain performance-sensitive kernel !! 80 Certain performance-sensitive kernel code, such as trace points,
93 scheduler functionality, networking !! 81 scheduler functionality, networking code and KVM have such
94 branches and include support for thi !! 82 branches and include support for this optimization technique.
95 !! 83
96 If it is detected that the compiler !! 84 If it is detected that the compiler has support for "asm goto",
97 the kernel will compile such branche !! 85 the kernel will compile such branches with just a nop
98 instruction. When the condition flag !! 86 instruction. When the condition flag is toggled to true, the
99 nop will be converted to a jump inst !! 87 nop will be converted to a jump instruction to execute the
100 conditional block of instructions. !! 88 conditional block of instructions.
101 !! 89
102 This technique lowers overhead and s !! 90 This technique lowers overhead and stress on the branch prediction
103 of the processor and generally makes !! 91 of the processor and generally makes the kernel faster. The update
104 of the condition is slower, but thos !! 92 of the condition is slower, but those are always very rare.
105 93
106 ( On 32-bit x86, the necessary optio !! 94 ( On 32-bit x86, the necessary options added to the compiler
107 flags may increase the size of the !! 95 flags may increase the size of the kernel slightly. )
108 96
109 config STATIC_KEYS_SELFTEST 97 config STATIC_KEYS_SELFTEST
110 bool "Static key selftest" 98 bool "Static key selftest"
111 depends on JUMP_LABEL 99 depends on JUMP_LABEL
112 help 100 help
113 Boot time self-test of the branch pa 101 Boot time self-test of the branch patching code.
114 102
115 config STATIC_CALL_SELFTEST <<
116 bool "Static call selftest" <<
117 depends on HAVE_STATIC_CALL <<
118 help <<
119 Boot time self-test of the call patc <<
120 <<
121 config OPTPROBES 103 config OPTPROBES
122 def_bool y 104 def_bool y
123 depends on KPROBES && HAVE_OPTPROBES 105 depends on KPROBES && HAVE_OPTPROBES
124 select NEED_TASKS_RCU !! 106 select TASKS_RCU if PREEMPT
125 107
126 config KPROBES_ON_FTRACE 108 config KPROBES_ON_FTRACE
127 def_bool y 109 def_bool y
128 depends on KPROBES && HAVE_KPROBES_ON_ 110 depends on KPROBES && HAVE_KPROBES_ON_FTRACE
129 depends on DYNAMIC_FTRACE_WITH_REGS 111 depends on DYNAMIC_FTRACE_WITH_REGS
130 help 112 help
131 If function tracer is enabled and th !! 113 If function tracer is enabled and the arch supports full
132 passing of pt_regs to function traci !! 114 passing of pt_regs to function tracing, then kprobes can
133 optimize on top of function tracing. !! 115 optimize on top of function tracing.
134 116
135 config UPROBES 117 config UPROBES
136 def_bool n 118 def_bool n
137 depends on ARCH_SUPPORTS_UPROBES 119 depends on ARCH_SUPPORTS_UPROBES
138 help 120 help
139 Uprobes is the user-space counterpar 121 Uprobes is the user-space counterpart to kprobes: they
140 enable instrumentation applications 122 enable instrumentation applications (such as 'perf probe')
141 to establish unintrusive probes in u 123 to establish unintrusive probes in user-space binaries and
142 libraries, by executing handler func 124 libraries, by executing handler functions when the probes
143 are hit by user-space applications. 125 are hit by user-space applications.
144 126
145 ( These probes come in the form of s 127 ( These probes come in the form of single-byte breakpoints,
146 managed by the kernel and kept tra 128 managed by the kernel and kept transparent to the probed
147 application. ) 129 application. )
148 130
149 config HAVE_64BIT_ALIGNED_ACCESS 131 config HAVE_64BIT_ALIGNED_ACCESS
150 def_bool 64BIT && !HAVE_EFFICIENT_UNAL 132 def_bool 64BIT && !HAVE_EFFICIENT_UNALIGNED_ACCESS
151 help 133 help
152 Some architectures require 64 bit ac 134 Some architectures require 64 bit accesses to be 64 bit
153 aligned, which also requires structs 135 aligned, which also requires structs containing 64 bit values
154 to be 64 bit aligned too. This inclu 136 to be 64 bit aligned too. This includes some 32 bit
155 architectures which can do 64 bit ac 137 architectures which can do 64 bit accesses, as well as 64 bit
156 architectures without unaligned acce 138 architectures without unaligned access.
157 139
158 This symbol should be selected by an 140 This symbol should be selected by an architecture if 64 bit
159 accesses are required to be 64 bit a 141 accesses are required to be 64 bit aligned in this way even
160 though it is not a 64 bit architectu 142 though it is not a 64 bit architecture.
161 143
162 See Documentation/core-api/unaligned !! 144 See Documentation/unaligned-memory-access.txt for more
163 more information on the topic of una !! 145 information on the topic of unaligned memory accesses.
164 146
165 config HAVE_EFFICIENT_UNALIGNED_ACCESS 147 config HAVE_EFFICIENT_UNALIGNED_ACCESS
166 bool 148 bool
167 help 149 help
168 Some architectures are unable to per 150 Some architectures are unable to perform unaligned accesses
169 without the use of get_unaligned/put 151 without the use of get_unaligned/put_unaligned. Others are
170 unable to perform such accesses effi 152 unable to perform such accesses efficiently (e.g. trap on
171 unaligned access and require fixing 153 unaligned access and require fixing it up in the exception
172 handler.) 154 handler.)
173 155
174 This symbol should be selected by an 156 This symbol should be selected by an architecture if it can
175 perform unaligned accesses efficient 157 perform unaligned accesses efficiently to allow different
176 code paths to be selected for these 158 code paths to be selected for these cases. Some network
177 drivers, for example, could opt to n 159 drivers, for example, could opt to not fix up alignment
178 problems with received packets if do 160 problems with received packets if doing so would not help
179 much. 161 much.
180 162
181 See Documentation/core-api/unaligned !! 163 See Documentation/unaligned-memory-access.txt for more
182 information on the topic of unaligne 164 information on the topic of unaligned memory accesses.
183 165
184 config ARCH_USE_BUILTIN_BSWAP 166 config ARCH_USE_BUILTIN_BSWAP
185 bool !! 167 bool
186 help !! 168 help
187 Modern versions of GCC (since 4.4) h !! 169 Modern versions of GCC (since 4.4) have builtin functions
188 for handling byte-swapping. Using th !! 170 for handling byte-swapping. Using these, instead of the old
189 inline assembler that the architectu !! 171 inline assembler that the architecture code provides in the
190 __arch_bswapXX() macros, allows the !! 172 __arch_bswapXX() macros, allows the compiler to see what's
191 happening and offers more opportunit !! 173 happening and offers more opportunity for optimisation. In
192 particular, the compiler will be abl !! 174 particular, the compiler will be able to combine the byteswap
193 with a nearby load or store and use !! 175 with a nearby load or store and use load-and-swap or
194 store-and-swap instructions if the a !! 176 store-and-swap instructions if the architecture has them. It
195 should almost *never* result in code !! 177 should almost *never* result in code which is worse than the
196 hand-coded assembler in <asm/swab.h> !! 178 hand-coded assembler in <asm/swab.h>. But just in case it
197 does, the use of the builtins is opt !! 179 does, the use of the builtins is optional.
198 !! 180
199 Any architecture with load-and-swap !! 181 Any architecture with load-and-swap or store-and-swap
200 instructions should set this. And it !! 182 instructions should set this. And it shouldn't hurt to set it
201 on architectures that don't have suc !! 183 on architectures that don't have such instructions.
202 184
203 config KRETPROBES 185 config KRETPROBES
204 def_bool y 186 def_bool y
205 depends on KPROBES && (HAVE_KRETPROBES !! 187 depends on KPROBES && HAVE_KRETPROBES
206 <<
207 config KRETPROBE_ON_RETHOOK <<
208 def_bool y <<
209 depends on HAVE_RETHOOK <<
210 depends on KRETPROBES <<
211 select RETHOOK <<
212 188
213 config USER_RETURN_NOTIFIER 189 config USER_RETURN_NOTIFIER
214 bool 190 bool
215 depends on HAVE_USER_RETURN_NOTIFIER 191 depends on HAVE_USER_RETURN_NOTIFIER
216 help 192 help
217 Provide a kernel-internal notificati 193 Provide a kernel-internal notification when a cpu is about to
218 switch to user mode. 194 switch to user mode.
219 195
220 config HAVE_IOREMAP_PROT 196 config HAVE_IOREMAP_PROT
221 bool 197 bool
222 198
223 config HAVE_KPROBES 199 config HAVE_KPROBES
224 bool 200 bool
225 201
226 config HAVE_KRETPROBES 202 config HAVE_KRETPROBES
227 bool 203 bool
228 204
229 config HAVE_OPTPROBES 205 config HAVE_OPTPROBES
230 bool 206 bool
231 207
232 config HAVE_KPROBES_ON_FTRACE 208 config HAVE_KPROBES_ON_FTRACE
233 bool 209 bool
234 210
235 config ARCH_CORRECT_STACKTRACE_ON_KRETPROBE <<
236 bool <<
237 help <<
238 Since kretprobes modifies return add <<
239 stacktrace may see the kretprobe tra <<
240 of correct one. If the architecture <<
241 unwinder can adjust such entries, se <<
242 <<
243 config HAVE_FUNCTION_ERROR_INJECTION 211 config HAVE_FUNCTION_ERROR_INJECTION
244 bool 212 bool
245 213
246 config HAVE_NMI 214 config HAVE_NMI
247 bool 215 bool
248 216
249 config HAVE_FUNCTION_DESCRIPTORS <<
250 bool <<
251 <<
252 config TRACE_IRQFLAGS_SUPPORT <<
253 bool <<
254 <<
255 config TRACE_IRQFLAGS_NMI_SUPPORT <<
256 bool <<
257 <<
258 # 217 #
259 # An arch should select this if it provides al 218 # An arch should select this if it provides all these things:
260 # 219 #
261 # task_pt_regs() in asm/process 220 # task_pt_regs() in asm/processor.h or asm/ptrace.h
262 # arch_has_single_step() if there is ha 221 # arch_has_single_step() if there is hardware single-step support
263 # arch_has_block_step() if there is ha 222 # arch_has_block_step() if there is hardware block-step support
264 # asm/syscall.h supplying asm- 223 # asm/syscall.h supplying asm-generic/syscall.h interface
265 # linux/regset.h user_regset in 224 # linux/regset.h user_regset interfaces
266 # CORE_DUMP_USE_REGSET #define'd in l 225 # CORE_DUMP_USE_REGSET #define'd in linux/elf.h
267 # TIF_SYSCALL_TRACE calls ptrace_r !! 226 # TIF_SYSCALL_TRACE calls tracehook_report_syscall_{entry,exit}
268 # TIF_NOTIFY_RESUME calls resume_u !! 227 # TIF_NOTIFY_RESUME calls tracehook_notify_resume()
>> 228 # signal delivery calls tracehook_signal_handler()
269 # 229 #
270 config HAVE_ARCH_TRACEHOOK 230 config HAVE_ARCH_TRACEHOOK
271 bool 231 bool
272 232
273 config HAVE_DMA_CONTIGUOUS 233 config HAVE_DMA_CONTIGUOUS
274 bool 234 bool
275 235
276 config GENERIC_SMP_IDLE_THREAD 236 config GENERIC_SMP_IDLE_THREAD
277 bool !! 237 bool
278 238
279 config GENERIC_IDLE_POLL_SETUP 239 config GENERIC_IDLE_POLL_SETUP
280 bool !! 240 bool
281 241
282 config ARCH_HAS_FORTIFY_SOURCE 242 config ARCH_HAS_FORTIFY_SOURCE
283 bool 243 bool
284 help 244 help
285 An architecture should select this w 245 An architecture should select this when it can successfully
286 build and run with CONFIG_FORTIFY_SO 246 build and run with CONFIG_FORTIFY_SOURCE.
287 247
288 # <<
289 # Select if the arch provides a historic keepi <<
290 # command line option <<
291 # <<
292 config ARCH_HAS_KEEPINITRD <<
293 bool <<
294 <<
295 # Select if arch has all set_memory_ro/rw/x/nx 248 # Select if arch has all set_memory_ro/rw/x/nx() functions in asm/cacheflush.h
296 config ARCH_HAS_SET_MEMORY 249 config ARCH_HAS_SET_MEMORY
297 bool 250 bool
298 251
299 # Select if arch has all set_direct_map_invali <<
300 config ARCH_HAS_SET_DIRECT_MAP <<
301 bool <<
302 <<
303 # <<
304 # Select if the architecture provides the arch <<
305 # either provide an uncached segment alias for <<
306 # to remap the page tables in place. <<
307 # <<
308 config ARCH_HAS_DMA_SET_UNCACHED <<
309 bool <<
310 <<
311 # <<
312 # Select if the architectures provides the arc <<
313 # to undo an in-place page table remap for unc <<
314 # <<
315 config ARCH_HAS_DMA_CLEAR_UNCACHED <<
316 bool <<
317 <<
318 config ARCH_HAS_CPU_FINALIZE_INIT 252 config ARCH_HAS_CPU_FINALIZE_INIT
319 bool 253 bool
320 254
321 # The architecture has a per-task state that i !! 255 # Select if arch init_task must go in the __init_task_data section
322 config ARCH_HAS_CPU_PASID !! 256 config ARCH_TASK_STRUCT_ON_STACK
>> 257 bool
>> 258
>> 259 # Select if arch has its private alloc_task_struct() function
>> 260 config ARCH_TASK_STRUCT_ALLOCATOR
323 bool 261 bool
324 select IOMMU_MM_DATA <<
325 262
326 config HAVE_ARCH_THREAD_STRUCT_WHITELIST 263 config HAVE_ARCH_THREAD_STRUCT_WHITELIST
327 bool 264 bool
>> 265 depends on !ARCH_TASK_STRUCT_ALLOCATOR
328 help 266 help
329 An architecture should select this t 267 An architecture should select this to provide hardened usercopy
330 knowledge about what region of the t 268 knowledge about what region of the thread_struct should be
331 whitelisted for copying to userspace 269 whitelisted for copying to userspace. Normally this is only the
332 FPU registers. Specifically, arch_th 270 FPU registers. Specifically, arch_thread_struct_whitelist()
333 should be implemented. Without this, 271 should be implemented. Without this, the entire thread_struct
334 field in task_struct will be left wh 272 field in task_struct will be left whitelisted.
335 273
336 # Select if arch wants to size task_struct dyn !! 274 # Select if arch has its private alloc_thread_stack() function
337 config ARCH_WANTS_DYNAMIC_TASK_STRUCT !! 275 config ARCH_THREAD_STACK_ALLOCATOR
338 bool <<
339 <<
340 config ARCH_WANTS_NO_INSTR <<
341 bool <<
342 help <<
343 An architecture should select this i <<
344 functions to denote that the toolcha <<
345 functions and is required for correc <<
346 <<
347 config ARCH_32BIT_OFF_T <<
348 bool <<
349 depends on !64BIT <<
350 help <<
351 All new 32-bit architectures should <<
352 userspace side which corresponds to <<
353 is the requirement for modern ABIs. <<
354 still support 32-bit off_t. This opt <<
355 architectures explicitly. <<
356 <<
357 # Selected by 64 bit architectures which have <<
358 config ARCH_32BIT_USTAT_F_TINODE <<
359 bool 276 bool
360 277
361 config HAVE_ASM_MODVERSIONS !! 278 # Select if arch wants to size task_struct dynamically via arch_task_struct_size:
>> 279 config ARCH_WANTS_DYNAMIC_TASK_STRUCT
362 bool 280 bool
363 help <<
364 This symbol should be selected by an <<
365 <asm/asm-prototypes.h> to support th <<
366 exported from assembly code. <<
367 281
368 config HAVE_REGS_AND_STACK_ACCESS_API 282 config HAVE_REGS_AND_STACK_ACCESS_API
369 bool 283 bool
370 help 284 help
371 This symbol should be selected by an !! 285 This symbol should be selected by an architecure if it supports
372 the API needed to access registers a 286 the API needed to access registers and stack entries from pt_regs,
373 declared in asm/ptrace.h 287 declared in asm/ptrace.h
374 For example the kprobes-based event 288 For example the kprobes-based event tracer needs this API.
375 289
376 config HAVE_RSEQ 290 config HAVE_RSEQ
377 bool 291 bool
378 depends on HAVE_REGS_AND_STACK_ACCESS_ 292 depends on HAVE_REGS_AND_STACK_ACCESS_API
379 help 293 help
380 This symbol should be selected by an 294 This symbol should be selected by an architecture if it
381 supports an implementation of restar 295 supports an implementation of restartable sequences.
382 296
383 config HAVE_RUST !! 297 config HAVE_CLK
384 bool 298 bool
385 help 299 help
386 This symbol should be selected by an !! 300 The <linux/clk.h> calls support software clock gating and
387 supports Rust. !! 301 thus are a key power management tool on many systems.
388 <<
389 config HAVE_FUNCTION_ARG_ACCESS_API <<
390 bool <<
391 help <<
392 This symbol should be selected by an <<
393 the API needed to access function ar <<
394 declared in asm/ptrace.h <<
395 302
396 config HAVE_HW_BREAKPOINT 303 config HAVE_HW_BREAKPOINT
397 bool 304 bool
398 depends on PERF_EVENTS 305 depends on PERF_EVENTS
399 306
400 config HAVE_MIXED_BREAKPOINTS_REGS 307 config HAVE_MIXED_BREAKPOINTS_REGS
401 bool 308 bool
402 depends on HAVE_HW_BREAKPOINT 309 depends on HAVE_HW_BREAKPOINT
403 help 310 help
404 Depending on the arch implementation 311 Depending on the arch implementation of hardware breakpoints,
405 some of them have separate registers 312 some of them have separate registers for data and instruction
406 breakpoints addresses, others have m 313 breakpoints addresses, others have mixed registers to store
407 them but define the access type in a 314 them but define the access type in a control register.
408 Select this option if your arch impl 315 Select this option if your arch implements breakpoints under the
409 latter fashion. 316 latter fashion.
410 317
411 config HAVE_USER_RETURN_NOTIFIER 318 config HAVE_USER_RETURN_NOTIFIER
412 bool 319 bool
413 320
414 config HAVE_PERF_EVENTS_NMI 321 config HAVE_PERF_EVENTS_NMI
415 bool 322 bool
416 help 323 help
417 System hardware can generate an NMI 324 System hardware can generate an NMI using the perf event
418 subsystem. Also has support for cal 325 subsystem. Also has support for calculating CPU cycle events
419 to determine how many clock cycles i 326 to determine how many clock cycles in a given period.
420 327
421 config HAVE_HARDLOCKUP_DETECTOR_PERF 328 config HAVE_HARDLOCKUP_DETECTOR_PERF
422 bool 329 bool
423 depends on HAVE_PERF_EVENTS_NMI 330 depends on HAVE_PERF_EVENTS_NMI
424 help 331 help
425 The arch chooses to use the generic 332 The arch chooses to use the generic perf-NMI-based hardlockup
426 detector. Must define HAVE_PERF_EVEN 333 detector. Must define HAVE_PERF_EVENTS_NMI.
427 334
428 config HAVE_HARDLOCKUP_DETECTOR_ARCH !! 335 config HAVE_NMI_WATCHDOG
>> 336 depends on HAVE_NMI
429 bool 337 bool
430 help 338 help
431 The arch provides its own hardlockup !! 339 The arch provides a low level NMI watchdog. It provides
432 of the generic ones. !! 340 asm/nmi.h, and defines its own arch_touch_nmi_watchdog().
433 341
434 It uses the same command line parame !! 342 config HAVE_HARDLOCKUP_DETECTOR_ARCH
435 as the generic hardlockup detectors. !! 343 bool
>> 344 select HAVE_NMI_WATCHDOG
>> 345 help
>> 346 The arch chooses to provide its own hardlockup detector, which is
>> 347 a superset of the HAVE_NMI_WATCHDOG. It also conforms to config
>> 348 interfaces and parameters provided by hardlockup detector subsystem.
436 349
437 config HAVE_PERF_REGS 350 config HAVE_PERF_REGS
438 bool 351 bool
439 help 352 help
440 Support selective register dumps for 353 Support selective register dumps for perf events. This includes
441 bit-mapping of each registers and a 354 bit-mapping of each registers and a unique architecture id.
442 355
443 config HAVE_PERF_USER_STACK_DUMP 356 config HAVE_PERF_USER_STACK_DUMP
444 bool 357 bool
445 help 358 help
446 Support user stack dumps for perf ev 359 Support user stack dumps for perf event samples. This needs
447 access to the user stack pointer whi 360 access to the user stack pointer which is not unified across
448 architectures. 361 architectures.
449 362
450 config HAVE_ARCH_JUMP_LABEL 363 config HAVE_ARCH_JUMP_LABEL
451 bool 364 bool
452 365
453 config HAVE_ARCH_JUMP_LABEL_RELATIVE !! 366 config HAVE_RCU_TABLE_FREE
454 bool <<
455 <<
456 config MMU_GATHER_TABLE_FREE <<
457 bool <<
458 <<
459 config MMU_GATHER_RCU_TABLE_FREE <<
460 bool 367 bool
461 select MMU_GATHER_TABLE_FREE <<
462 368
463 config MMU_GATHER_PAGE_SIZE !! 369 config HAVE_RCU_TABLE_INVALIDATE
464 bool 370 bool
465 371
466 config MMU_GATHER_NO_RANGE <<
467 bool <<
468 select MMU_GATHER_MERGE_VMAS <<
469 <<
470 config MMU_GATHER_NO_FLUSH_CACHE <<
471 bool <<
472 <<
473 config MMU_GATHER_MERGE_VMAS <<
474 bool <<
475 <<
476 config MMU_GATHER_NO_GATHER <<
477 bool <<
478 depends on MMU_GATHER_TABLE_FREE <<
479 <<
480 config ARCH_WANT_IRQS_OFF_ACTIVATE_MM 372 config ARCH_WANT_IRQS_OFF_ACTIVATE_MM
481 bool 373 bool
482 help 374 help
483 Temporary select until all architect 375 Temporary select until all architectures can be converted to have
484 irqs disabled over activate_mm. Arch 376 irqs disabled over activate_mm. Architectures that do IPI based TLB
485 shootdowns should enable this. 377 shootdowns should enable this.
486 378
487 # Use normal mm refcounting for MMU_LAZY_TLB k <<
488 # MMU_LAZY_TLB_REFCOUNT=n can improve the scal <<
489 # to/from kernel threads when the same mm is r <<
490 # multi-threaded application), by reducing con <<
491 # <<
492 # This can be disabled if the architecture ens <<
493 # "lazy tlb" beyond its final refcount (i.e., <<
494 # or its kernel page tables). This could be ar <<
495 # final exit(2) TLB flush, for example. <<
496 # <<
497 # To implement this, an arch *must*: <<
498 # Ensure the _lazy_tlb variants of mmgrab/mmdr <<
499 # the lazy tlb reference of a kthread's ->acti <<
500 # converted already). <<
501 config MMU_LAZY_TLB_REFCOUNT <<
502 def_bool y <<
503 depends on !MMU_LAZY_TLB_SHOOTDOWN <<
504 <<
505 # This option allows MMU_LAZY_TLB_REFCOUNT=n. <<
506 # mm as a lazy tlb beyond its last reference c <<
507 # users before the mm is deallocated. __mmdrop <<
508 # be using the mm as a lazy tlb, so that they <<
509 # init_mm for their active mm. mm_cpumask(mm) <<
510 # may be using mm as a lazy tlb mm. <<
511 # <<
512 # To implement this, an arch *must*: <<
513 # - At the time of the final mmdrop of the mm, <<
514 # at least all possible CPUs in which the mm <<
515 # - It must meet the requirements for MMU_LAZY <<
516 config MMU_LAZY_TLB_SHOOTDOWN <<
517 bool <<
518 <<
519 config ARCH_HAVE_NMI_SAFE_CMPXCHG 379 config ARCH_HAVE_NMI_SAFE_CMPXCHG
520 bool 380 bool
521 381
522 config ARCH_HAVE_EXTRA_ELF_NOTES <<
523 bool <<
524 help <<
525 An architecture should select this i <<
526 arch-specific ELF note section to co <<
527 functions: elf_coredump_extra_notes_ <<
528 elf_coredump_extra_notes_write() whi <<
529 dumper. <<
530 <<
531 config ARCH_HAS_NMI_SAFE_THIS_CPU_OPS <<
532 bool <<
533 <<
534 config HAVE_ALIGNED_STRUCT_PAGE 382 config HAVE_ALIGNED_STRUCT_PAGE
535 bool 383 bool
536 help 384 help
537 This makes sure that struct pages ar 385 This makes sure that struct pages are double word aligned and that
538 e.g. the SLUB allocator can perform 386 e.g. the SLUB allocator can perform double word atomic operations
539 on a struct page for better performa 387 on a struct page for better performance. However selecting this
540 might increase the size of a struct 388 might increase the size of a struct page by a word.
541 389
542 config HAVE_CMPXCHG_LOCAL 390 config HAVE_CMPXCHG_LOCAL
543 bool 391 bool
544 392
545 config HAVE_CMPXCHG_DOUBLE 393 config HAVE_CMPXCHG_DOUBLE
546 bool 394 bool
547 395
548 config ARCH_WEAK_RELEASE_ACQUIRE 396 config ARCH_WEAK_RELEASE_ACQUIRE
549 bool 397 bool
550 398
551 config ARCH_WANT_IPC_PARSE_VERSION 399 config ARCH_WANT_IPC_PARSE_VERSION
552 bool 400 bool
553 401
554 config ARCH_WANT_COMPAT_IPC_PARSE_VERSION 402 config ARCH_WANT_COMPAT_IPC_PARSE_VERSION
555 bool 403 bool
556 404
557 config ARCH_WANT_OLD_COMPAT_IPC 405 config ARCH_WANT_OLD_COMPAT_IPC
558 select ARCH_WANT_COMPAT_IPC_PARSE_VERS 406 select ARCH_WANT_COMPAT_IPC_PARSE_VERSION
559 bool 407 bool
560 408
561 config HAVE_ARCH_SECCOMP <<
562 bool <<
563 help <<
564 An arch should select this symbol to <<
565 syscall policy), and must provide an <<
566 and compat syscalls if the asm-gener <<
567 - __NR_seccomp_read_32 <<
568 - __NR_seccomp_write_32 <<
569 - __NR_seccomp_exit_32 <<
570 - __NR_seccomp_sigreturn_32 <<
571 <<
572 config HAVE_ARCH_SECCOMP_FILTER 409 config HAVE_ARCH_SECCOMP_FILTER
573 bool 410 bool
574 select HAVE_ARCH_SECCOMP <<
575 help 411 help
576 An arch should select this symbol if 412 An arch should select this symbol if it provides all of these things:
577 - all the requirements for HAVE_ARCH <<
578 - syscall_get_arch() 413 - syscall_get_arch()
579 - syscall_get_arguments() 414 - syscall_get_arguments()
580 - syscall_rollback() 415 - syscall_rollback()
581 - syscall_set_return_value() 416 - syscall_set_return_value()
582 - SIGSYS siginfo_t support 417 - SIGSYS siginfo_t support
583 - secure_computing is called from a 418 - secure_computing is called from a ptrace_event()-safe context
584 - secure_computing return value is c 419 - secure_computing return value is checked and a return value of -1
585 results in the system call being s 420 results in the system call being skipped immediately.
586 - seccomp syscall wired up 421 - seccomp syscall wired up
587 - if !HAVE_SPARSE_SYSCALL_NR, have S <<
588 SECCOMP_ARCH_NATIVE_NR, SECCOMP_AR <<
589 COMPAT is supported, have the SECC <<
590 <<
591 config SECCOMP <<
592 prompt "Enable seccomp to safely execu <<
593 def_bool y <<
594 depends on HAVE_ARCH_SECCOMP <<
595 help <<
596 This kernel feature is useful for nu <<
597 that may need to handle untrusted by <<
598 execution. By using pipes or other t <<
599 to the process as file descriptors s <<
600 syscalls, it's possible to isolate t <<
601 own address space using seccomp. Onc <<
602 prctl(PR_SET_SECCOMP) or the seccomp <<
603 disabled and the task is only allowe <<
604 syscalls defined by each seccomp mod <<
605 <<
606 If unsure, say Y. <<
607 422
608 config SECCOMP_FILTER 423 config SECCOMP_FILTER
609 def_bool y 424 def_bool y
610 depends on HAVE_ARCH_SECCOMP_FILTER && 425 depends on HAVE_ARCH_SECCOMP_FILTER && SECCOMP && NET
611 help 426 help
612 Enable tasks to build secure computi 427 Enable tasks to build secure computing environments defined
613 in terms of Berkeley Packet Filter p 428 in terms of Berkeley Packet Filter programs which implement
614 task-defined system call filtering p 429 task-defined system call filtering polices.
615 430
616 See Documentation/userspace-api/secc 431 See Documentation/userspace-api/seccomp_filter.rst for details.
617 432
618 config SECCOMP_CACHE_DEBUG <<
619 bool "Show seccomp filter cache status <<
620 depends on SECCOMP_FILTER && !HAVE_SPA <<
621 depends on PROC_FS <<
622 help <<
623 This enables the /proc/pid/seccomp_c <<
624 seccomp cache data. The file format <<
625 the file requires CAP_SYS_ADMIN. <<
626 <<
627 This option is for debugging only. E <<
628 an adversary may be able to infer th <<
629 <<
630 If unsure, say N. <<
631 <<
632 config HAVE_ARCH_STACKLEAK <<
633 bool <<
634 help <<
635 An architecture should select this i <<
636 fills the used part of the kernel st <<
637 value before returning from system c <<
638 <<
639 config HAVE_STACKPROTECTOR 433 config HAVE_STACKPROTECTOR
640 bool 434 bool
641 help 435 help
642 An arch should select this symbol if 436 An arch should select this symbol if:
643 - it has implemented a stack canary 437 - it has implemented a stack canary (e.g. __stack_chk_guard)
644 438
>> 439 config CC_HAS_STACKPROTECTOR_NONE
>> 440 def_bool $(cc-option,-fno-stack-protector)
>> 441
645 config STACKPROTECTOR 442 config STACKPROTECTOR
646 bool "Stack Protector buffer overflow 443 bool "Stack Protector buffer overflow detection"
647 depends on HAVE_STACKPROTECTOR 444 depends on HAVE_STACKPROTECTOR
648 depends on $(cc-option,-fstack-protect 445 depends on $(cc-option,-fstack-protector)
649 default y 446 default y
650 help 447 help
651 This option turns on the "stack-prot 448 This option turns on the "stack-protector" GCC feature. This
652 feature puts, at the beginning of fu 449 feature puts, at the beginning of functions, a canary value on
653 the stack just before the return add 450 the stack just before the return address, and validates
654 the value just before actually retur 451 the value just before actually returning. Stack based buffer
655 overflows (that need to overwrite th 452 overflows (that need to overwrite this return address) now also
656 overwrite the canary, which gets det 453 overwrite the canary, which gets detected and the attack is then
657 neutralized via a kernel panic. 454 neutralized via a kernel panic.
658 455
659 Functions will have the stack-protec 456 Functions will have the stack-protector canary logic added if they
660 have an 8-byte or larger character a 457 have an 8-byte or larger character array on the stack.
661 458
662 This feature requires gcc version 4. 459 This feature requires gcc version 4.2 or above, or a distribution
663 gcc with the feature backported ("-f 460 gcc with the feature backported ("-fstack-protector").
664 461
665 On an x86 "defconfig" build, this fe 462 On an x86 "defconfig" build, this feature adds canary checks to
666 about 3% of all kernel functions, wh 463 about 3% of all kernel functions, which increases kernel code size
667 by about 0.3%. 464 by about 0.3%.
668 465
669 config STACKPROTECTOR_STRONG 466 config STACKPROTECTOR_STRONG
670 bool "Strong Stack Protector" 467 bool "Strong Stack Protector"
671 depends on STACKPROTECTOR 468 depends on STACKPROTECTOR
672 depends on $(cc-option,-fstack-protect 469 depends on $(cc-option,-fstack-protector-strong)
673 default y 470 default y
674 help 471 help
675 Functions will have the stack-protec 472 Functions will have the stack-protector canary logic added in any
676 of the following conditions: 473 of the following conditions:
677 474
678 - local variable's address used as p 475 - local variable's address used as part of the right hand side of an
679 assignment or function argument 476 assignment or function argument
680 - local variable is an array (or uni 477 - local variable is an array (or union containing an array),
681 regardless of array type or length 478 regardless of array type or length
682 - uses register local variables 479 - uses register local variables
683 480
684 This feature requires gcc version 4. 481 This feature requires gcc version 4.9 or above, or a distribution
685 gcc with the feature backported ("-f 482 gcc with the feature backported ("-fstack-protector-strong").
686 483
687 On an x86 "defconfig" build, this fe 484 On an x86 "defconfig" build, this feature adds canary checks to
688 about 20% of all kernel functions, w 485 about 20% of all kernel functions, which increases the kernel code
689 size by about 2%. 486 size by about 2%.
690 487
691 config ARCH_SUPPORTS_SHADOW_CALL_STACK <<
692 bool <<
693 help <<
694 An architecture should select this i <<
695 Shadow Call Stack and implements run <<
696 switching. <<
697 <<
698 config SHADOW_CALL_STACK <<
699 bool "Shadow Call Stack" <<
700 depends on ARCH_SUPPORTS_SHADOW_CALL_S <<
701 depends on DYNAMIC_FTRACE_WITH_ARGS || <<
702 depends on MMU <<
703 help <<
704 This option enables the compiler's S <<
705 uses a shadow stack to protect funct <<
706 being overwritten by an attacker. Mo <<
707 in the compiler's documentation: <<
708 <<
709 - Clang: https://clang.llvm.org/docs <<
710 - GCC: https://gcc.gnu.org/onlinedoc <<
711 <<
712 Note that security guarantees in the <<
713 ones documented for user space. The <<
714 of shadow stacks in memory, which me <<
715 reading and writing arbitrary memory <<
716 and hijack control flow by modifying <<
717 <<
718 config DYNAMIC_SCS <<
719 bool <<
720 help <<
721 Set by the arch code if it relies on <<
722 shadow call stack push and pop instr <<
723 compiler. <<
724 <<
725 config LTO <<
726 bool <<
727 help <<
728 Selected if the kernel will be built <<
729 <<
730 config LTO_CLANG <<
731 bool <<
732 select LTO <<
733 help <<
734 Selected if the kernel will be built <<
735 <<
736 config ARCH_SUPPORTS_LTO_CLANG <<
737 bool <<
738 help <<
739 An architecture should select this o <<
740 - compiling with Clang, <<
741 - compiling inline assembly with Cla <<
742 - and linking with LLD. <<
743 <<
744 config ARCH_SUPPORTS_LTO_CLANG_THIN <<
745 bool <<
746 help <<
747 An architecture should select this o <<
748 ThinLTO mode. <<
749 <<
750 config HAS_LTO_CLANG <<
751 def_bool y <<
752 depends on CC_IS_CLANG && LD_IS_LLD && <<
753 depends on $(success,$(NM) --help | he <<
754 depends on $(success,$(AR) --help | he <<
755 depends on ARCH_SUPPORTS_LTO_CLANG <<
756 depends on !FTRACE_MCOUNT_USE_RECORDMC <<
757 # https://github.com/ClangBuiltLinux/l <<
758 depends on (!KASAN || KASAN_HW_TAGS || <<
759 depends on (!KCOV || CLANG_VERSION >= <<
760 depends on !GCOV_KERNEL <<
761 help <<
762 The compiler and Kconfig options sup <<
763 LTO. <<
764 <<
765 choice <<
766 prompt "Link Time Optimization (LTO)" <<
767 default LTO_NONE <<
768 help <<
769 This option enables Link Time Optimi <<
770 compiler to optimize binaries global <<
771 <<
772 If unsure, select LTO_NONE. Note tha <<
773 so it's disabled by default. <<
774 <<
775 config LTO_NONE <<
776 bool "None" <<
777 help <<
778 Build the kernel normally, without L <<
779 <<
780 config LTO_CLANG_FULL <<
781 bool "Clang Full LTO (EXPERIMENTAL)" <<
782 depends on HAS_LTO_CLANG <<
783 depends on !COMPILE_TEST <<
784 select LTO_CLANG <<
785 help <<
786 This option enables Clang's full Lin <<
787 allows the compiler to optimize the <<
788 this option, the compiler generates <<
789 object files, and the actual compila <<
790 the LTO link step, which may take se <<
791 kernel configuration. More informati <<
792 documentation: <<
793 <<
794 https://llvm.org/docs/LinkTimeOpti <<
795 <<
796 During link time, this option can us <<
797 may take much longer than the ThinLT <<
798 <<
799 config LTO_CLANG_THIN <<
800 bool "Clang ThinLTO (EXPERIMENTAL)" <<
801 depends on HAS_LTO_CLANG && ARCH_SUPPO <<
802 select LTO_CLANG <<
803 help <<
804 This option enables Clang's ThinLTO, <<
805 optimization and faster incremental <<
806 CONFIG_LTO_CLANG_FULL option. More i <<
807 from Clang's documentation: <<
808 <<
809 https://clang.llvm.org/docs/ThinLT <<
810 <<
811 If unsure, say Y. <<
812 endchoice <<
813 <<
814 config ARCH_SUPPORTS_CFI_CLANG <<
815 bool <<
816 help <<
817 An architecture should select this o <<
818 Control-Flow Integrity (CFI) checkin <<
819 <<
820 config ARCH_USES_CFI_TRAPS <<
821 bool <<
822 <<
823 config CFI_CLANG <<
824 bool "Use Clang's Control Flow Integri <<
825 depends on ARCH_SUPPORTS_CFI_CLANG <<
826 depends on $(cc-option,-fsanitize=kcfi <<
827 help <<
828 This option enables Clang's forward- <<
829 (CFI) checking, where the compiler i <<
830 indirect function call to ensure the <<
831 the correct static type. This restri <<
832 makes it more difficult for an attac <<
833 the modification of stored function <<
834 found from Clang's documentation: <<
835 <<
836 https://clang.llvm.org/docs/Contro <<
837 <<
838 config CFI_ICALL_NORMALIZE_INTEGERS <<
839 bool "Normalize CFI tags for integers" <<
840 depends on CFI_CLANG <<
841 depends on HAVE_CFI_ICALL_NORMALIZE_IN <<
842 help <<
843 This option normalizes the CFI tags <<
844 integer types of the same size and s <<
845 tag. <<
846 <<
847 The option is separate from CONFIG_R <<
848 When working with build systems that <<
849 convenient to be able to turn on thi <<
850 turned on. <<
851 <<
852 This option is necessary for using C <<
853 <<
854 config HAVE_CFI_ICALL_NORMALIZE_INTEGERS_CLANG <<
855 def_bool y <<
856 depends on $(cc-option,-fsanitize=kcfi <<
857 # With GCOV/KASAN we need this fix: ht <<
858 depends on CLANG_VERSION >= 190103 || <<
859 <<
860 config HAVE_CFI_ICALL_NORMALIZE_INTEGERS_RUSTC <<
861 def_bool y <<
862 depends on HAVE_CFI_ICALL_NORMALIZE_IN <<
863 depends on RUSTC_VERSION >= 107900 <<
864 # With GCOV/KASAN we need this fix: ht <<
865 depends on (RUSTC_LLVM_VERSION >= 1901 <<
866 (!GCOV_KERNEL && !KASAN_GENERI <<
867 <<
868 config CFI_PERMISSIVE <<
869 bool "Use CFI in permissive mode" <<
870 depends on CFI_CLANG <<
871 help <<
872 When selected, Control Flow Integrit <<
873 warning instead of a kernel panic. T <<
874 for finding indirect call type misma <<
875 <<
876 If unsure, say N. <<
877 <<
878 config HAVE_ARCH_WITHIN_STACK_FRAMES 488 config HAVE_ARCH_WITHIN_STACK_FRAMES
879 bool 489 bool
880 help 490 help
881 An architecture should select this i 491 An architecture should select this if it can walk the kernel stack
882 frames to determine if an object is 492 frames to determine if an object is part of either the arguments
883 or local variables (i.e. that it exc 493 or local variables (i.e. that it excludes saved return addresses,
884 and similar) by implementing an inli 494 and similar) by implementing an inline arch_within_stack_frames(),
885 which is used by CONFIG_HARDENED_USE 495 which is used by CONFIG_HARDENED_USERCOPY.
886 496
887 config HAVE_CONTEXT_TRACKING_USER !! 497 config HAVE_CONTEXT_TRACKING
888 bool 498 bool
889 help 499 help
890 Provide kernel/user boundaries probe 500 Provide kernel/user boundaries probes necessary for subsystems
891 that need it, such as userspace RCU 501 that need it, such as userspace RCU extended quiescent state.
892 Syscalls need to be wrapped inside u !! 502 Syscalls need to be wrapped inside user_exit()-user_enter() through
893 optimized behind static key or throu !! 503 the slow path using TIF_NOHZ flag. Exceptions handlers must be
894 flag. Exceptions handlers must be wr !! 504 wrapped as well. Irqs are already protected inside
895 protected inside ct_irq_enter/ct_irq !! 505 rcu_irq_enter/rcu_irq_exit() but preemption or signal handling on
896 handling on irq exit still need to b !! 506 irq exit still need to be protected.
897 <<
898 config HAVE_CONTEXT_TRACKING_USER_OFFSTACK <<
899 bool <<
900 help <<
901 Architecture neither relies on excep <<
902 nor on schedule_user(). Also preempt <<
903 preempt_schedule_irq() can't be call <<
904 while context tracking is CT_STATE_U <<
905 entry implementation where the follo <<
906 critical entry code, ie: before user <<
907 <<
908 - Critical entry code isn't preempti <<
909 not interruptible). <<
910 - No use of RCU read side critical s <<
911 got called. <<
912 - No use of instrumentation, unless <<
913 called. <<
914 <<
915 config HAVE_TIF_NOHZ <<
916 bool <<
917 help <<
918 Arch relies on TIF_NOHZ and syscall <<
919 tracking calls to user_enter()/user_ <<
920 507
921 config HAVE_VIRT_CPU_ACCOUNTING 508 config HAVE_VIRT_CPU_ACCOUNTING
922 bool 509 bool
923 510
924 config HAVE_VIRT_CPU_ACCOUNTING_IDLE <<
925 bool <<
926 help <<
927 Architecture has its own way to acco <<
928 doesn't implement vtime_account_idle <<
929 <<
930 config ARCH_HAS_SCALED_CPUTIME 511 config ARCH_HAS_SCALED_CPUTIME
931 bool 512 bool
932 513
933 config HAVE_VIRT_CPU_ACCOUNTING_GEN 514 config HAVE_VIRT_CPU_ACCOUNTING_GEN
934 bool 515 bool
935 default y if 64BIT 516 default y if 64BIT
936 help 517 help
937 With VIRT_CPU_ACCOUNTING_GEN, cputim 518 With VIRT_CPU_ACCOUNTING_GEN, cputime_t becomes 64-bit.
938 Before enabling this option, arch co 519 Before enabling this option, arch code must be audited
939 to ensure there are no races in conc 520 to ensure there are no races in concurrent read/write of
940 cputime_t. For example, reading/writ 521 cputime_t. For example, reading/writing 64-bit cputime_t on
941 some 32-bit arches may require multi 522 some 32-bit arches may require multiple accesses, so proper
942 locking is needed to protect against 523 locking is needed to protect against concurrent accesses.
943 524
>> 525
944 config HAVE_IRQ_TIME_ACCOUNTING 526 config HAVE_IRQ_TIME_ACCOUNTING
945 bool 527 bool
946 help 528 help
947 Archs need to ensure they use a high 529 Archs need to ensure they use a high enough resolution clock to
948 support irq time accounting and then 530 support irq time accounting and then call enable_sched_clock_irqtime().
949 531
950 config HAVE_MOVE_PUD <<
951 bool <<
952 help <<
953 Architectures that select this are a <<
954 PUD level. If there are only 3 page <<
955 happens at the PGD level. <<
956 <<
957 config HAVE_MOVE_PMD <<
958 bool <<
959 help <<
960 Archs that select this are able to m <<
961 <<
962 config HAVE_ARCH_TRANSPARENT_HUGEPAGE 532 config HAVE_ARCH_TRANSPARENT_HUGEPAGE
963 bool 533 bool
964 534
965 config HAVE_ARCH_TRANSPARENT_HUGEPAGE_PUD 535 config HAVE_ARCH_TRANSPARENT_HUGEPAGE_PUD
966 bool 536 bool
967 537
968 config HAVE_ARCH_HUGE_VMAP 538 config HAVE_ARCH_HUGE_VMAP
969 bool 539 bool
970 540
971 # <<
972 # Archs that select this would be capable of <<
973 # arch_vmap_pmd_supported() returns true). Th <<
974 # must be used to enable allocations to use h <<
975 # <<
976 config HAVE_ARCH_HUGE_VMALLOC <<
977 depends on HAVE_ARCH_HUGE_VMAP <<
978 bool <<
979 <<
980 config ARCH_WANT_HUGE_PMD_SHARE <<
981 bool <<
982 <<
983 # Archs that want to use pmd_mkwrite on kernel <<
984 # if there are no userspace memory management <<
985 config ARCH_WANT_KERNEL_PMD_MKWRITE <<
986 bool <<
987 <<
988 config ARCH_WANT_PMD_MKWRITE <<
989 def_bool TRANSPARENT_HUGEPAGE || ARCH_ <<
990 <<
991 config HAVE_ARCH_SOFT_DIRTY 541 config HAVE_ARCH_SOFT_DIRTY
992 bool 542 bool
993 543
994 config HAVE_MOD_ARCH_SPECIFIC 544 config HAVE_MOD_ARCH_SPECIFIC
995 bool 545 bool
996 help 546 help
997 The arch uses struct mod_arch_specif 547 The arch uses struct mod_arch_specific to store data. Many arches
998 just need a simple module loader wit 548 just need a simple module loader without arch specific data - those
999 should not enable this. 549 should not enable this.
1000 550
1001 config MODULES_USE_ELF_RELA 551 config MODULES_USE_ELF_RELA
1002 bool 552 bool
1003 help 553 help
1004 Modules only use ELF RELA relocatio 554 Modules only use ELF RELA relocations. Modules with ELF REL
1005 relocations will give an error. 555 relocations will give an error.
1006 556
1007 config MODULES_USE_ELF_REL 557 config MODULES_USE_ELF_REL
1008 bool 558 bool
1009 help 559 help
1010 Modules only use ELF REL relocation 560 Modules only use ELF REL relocations. Modules with ELF RELA
1011 relocations will give an error. 561 relocations will give an error.
1012 562
1013 config ARCH_WANTS_MODULES_DATA_IN_VMALLOC <<
1014 bool <<
1015 help <<
1016 For architectures like powerpc/32 w <<
1017 allocation and need to allocate mod <<
1018 <<
1019 config ARCH_WANTS_EXECMEM_LATE <<
1020 bool <<
1021 help <<
1022 For architectures that do not alloc <<
1023 boot, but rather require its initia <<
1024 enough entropy for module space ran <<
1025 arm64. <<
1026 <<
1027 config HAVE_IRQ_EXIT_ON_IRQ_STACK 563 config HAVE_IRQ_EXIT_ON_IRQ_STACK
1028 bool 564 bool
1029 help 565 help
1030 Architecture doesn't only execute t 566 Architecture doesn't only execute the irq handler on the irq stack
1031 but also irq_exit(). This way we ca 567 but also irq_exit(). This way we can process softirqs on this irq
1032 stack instead of switching to a new 568 stack instead of switching to a new one when we call __do_softirq()
1033 in the end of an hardirq. 569 in the end of an hardirq.
1034 This spares a stack switch and impr 570 This spares a stack switch and improves cache usage on softirq
1035 processing. 571 processing.
1036 572
1037 config HAVE_SOFTIRQ_ON_OWN_STACK <<
1038 bool <<
1039 help <<
1040 Architecture provides a function to <<
1041 separate stack. <<
1042 <<
1043 config SOFTIRQ_ON_OWN_STACK <<
1044 def_bool HAVE_SOFTIRQ_ON_OWN_STACK && <<
1045 <<
1046 config ALTERNATE_USER_ADDRESS_SPACE <<
1047 bool <<
1048 help <<
1049 Architectures set this when the CPU <<
1050 spaces for kernel and user space po <<
1051 access_ok() check on a __user point <<
1052 <<
1053 config PGTABLE_LEVELS 573 config PGTABLE_LEVELS
1054 int 574 int
1055 default 2 575 default 2
1056 576
1057 config ARCH_HAS_ELF_RANDOMIZE 577 config ARCH_HAS_ELF_RANDOMIZE
1058 bool 578 bool
1059 help 579 help
1060 An architecture supports choosing r 580 An architecture supports choosing randomized locations for
1061 stack, mmap, brk, and ET_DYN. Defin 581 stack, mmap, brk, and ET_DYN. Defined functions:
1062 - arch_mmap_rnd() 582 - arch_mmap_rnd()
1063 - arch_randomize_brk() 583 - arch_randomize_brk()
1064 584
1065 config HAVE_ARCH_MMAP_RND_BITS 585 config HAVE_ARCH_MMAP_RND_BITS
1066 bool 586 bool
1067 help 587 help
1068 An arch should select this symbol i 588 An arch should select this symbol if it supports setting a variable
1069 number of bits for use in establish 589 number of bits for use in establishing the base address for mmap
1070 allocations, has MMU enabled and pr 590 allocations, has MMU enabled and provides values for both:
1071 - ARCH_MMAP_RND_BITS_MIN 591 - ARCH_MMAP_RND_BITS_MIN
1072 - ARCH_MMAP_RND_BITS_MAX 592 - ARCH_MMAP_RND_BITS_MAX
1073 593
1074 config HAVE_EXIT_THREAD 594 config HAVE_EXIT_THREAD
1075 bool 595 bool
1076 help 596 help
1077 An architecture implements exit_thr 597 An architecture implements exit_thread.
1078 598
1079 config ARCH_MMAP_RND_BITS_MIN 599 config ARCH_MMAP_RND_BITS_MIN
1080 int 600 int
1081 601
1082 config ARCH_MMAP_RND_BITS_MAX 602 config ARCH_MMAP_RND_BITS_MAX
1083 int 603 int
1084 604
1085 config ARCH_MMAP_RND_BITS_DEFAULT 605 config ARCH_MMAP_RND_BITS_DEFAULT
1086 int 606 int
1087 607
1088 config ARCH_MMAP_RND_BITS 608 config ARCH_MMAP_RND_BITS
1089 int "Number of bits to use for ASLR o 609 int "Number of bits to use for ASLR of mmap base address" if EXPERT
1090 range ARCH_MMAP_RND_BITS_MIN ARCH_MMA 610 range ARCH_MMAP_RND_BITS_MIN ARCH_MMAP_RND_BITS_MAX
1091 default ARCH_MMAP_RND_BITS_DEFAULT if 611 default ARCH_MMAP_RND_BITS_DEFAULT if ARCH_MMAP_RND_BITS_DEFAULT
1092 default ARCH_MMAP_RND_BITS_MIN 612 default ARCH_MMAP_RND_BITS_MIN
1093 depends on HAVE_ARCH_MMAP_RND_BITS 613 depends on HAVE_ARCH_MMAP_RND_BITS
1094 help 614 help
1095 This value can be used to select th 615 This value can be used to select the number of bits to use to
1096 determine the random offset to the 616 determine the random offset to the base address of vma regions
1097 resulting from mmap allocations. Th 617 resulting from mmap allocations. This value will be bounded
1098 by the architecture's minimum and m 618 by the architecture's minimum and maximum supported values.
1099 619
1100 This value can be changed after boo 620 This value can be changed after boot using the
1101 /proc/sys/vm/mmap_rnd_bits tunable 621 /proc/sys/vm/mmap_rnd_bits tunable
1102 622
1103 config HAVE_ARCH_MMAP_RND_COMPAT_BITS 623 config HAVE_ARCH_MMAP_RND_COMPAT_BITS
1104 bool 624 bool
1105 help 625 help
1106 An arch should select this symbol i 626 An arch should select this symbol if it supports running applications
1107 in compatibility mode, supports set 627 in compatibility mode, supports setting a variable number of bits for
1108 use in establishing the base addres 628 use in establishing the base address for mmap allocations, has MMU
1109 enabled and provides values for bot 629 enabled and provides values for both:
1110 - ARCH_MMAP_RND_COMPAT_BITS_MIN 630 - ARCH_MMAP_RND_COMPAT_BITS_MIN
1111 - ARCH_MMAP_RND_COMPAT_BITS_MAX 631 - ARCH_MMAP_RND_COMPAT_BITS_MAX
1112 632
1113 config ARCH_MMAP_RND_COMPAT_BITS_MIN 633 config ARCH_MMAP_RND_COMPAT_BITS_MIN
1114 int 634 int
1115 635
1116 config ARCH_MMAP_RND_COMPAT_BITS_MAX 636 config ARCH_MMAP_RND_COMPAT_BITS_MAX
1117 int 637 int
1118 638
1119 config ARCH_MMAP_RND_COMPAT_BITS_DEFAULT 639 config ARCH_MMAP_RND_COMPAT_BITS_DEFAULT
1120 int 640 int
1121 641
1122 config ARCH_MMAP_RND_COMPAT_BITS 642 config ARCH_MMAP_RND_COMPAT_BITS
1123 int "Number of bits to use for ASLR o 643 int "Number of bits to use for ASLR of mmap base address for compatible applications" if EXPERT
1124 range ARCH_MMAP_RND_COMPAT_BITS_MIN A 644 range ARCH_MMAP_RND_COMPAT_BITS_MIN ARCH_MMAP_RND_COMPAT_BITS_MAX
1125 default ARCH_MMAP_RND_COMPAT_BITS_DEF 645 default ARCH_MMAP_RND_COMPAT_BITS_DEFAULT if ARCH_MMAP_RND_COMPAT_BITS_DEFAULT
1126 default ARCH_MMAP_RND_COMPAT_BITS_MIN 646 default ARCH_MMAP_RND_COMPAT_BITS_MIN
1127 depends on HAVE_ARCH_MMAP_RND_COMPAT_ 647 depends on HAVE_ARCH_MMAP_RND_COMPAT_BITS
1128 help 648 help
1129 This value can be used to select th 649 This value can be used to select the number of bits to use to
1130 determine the random offset to the 650 determine the random offset to the base address of vma regions
1131 resulting from mmap allocations for 651 resulting from mmap allocations for compatible applications This
1132 value will be bounded by the archit 652 value will be bounded by the architecture's minimum and maximum
1133 supported values. 653 supported values.
1134 654
1135 This value can be changed after boo 655 This value can be changed after boot using the
1136 /proc/sys/vm/mmap_rnd_compat_bits t 656 /proc/sys/vm/mmap_rnd_compat_bits tunable
1137 657
1138 config HAVE_ARCH_COMPAT_MMAP_BASES 658 config HAVE_ARCH_COMPAT_MMAP_BASES
1139 bool 659 bool
1140 help 660 help
1141 This allows 64bit applications to i 661 This allows 64bit applications to invoke 32-bit mmap() syscall
1142 and vice-versa 32-bit applications 662 and vice-versa 32-bit applications to call 64-bit mmap().
1143 Required for applications doing dif 663 Required for applications doing different bitness syscalls.
1144 664
1145 config HAVE_PAGE_SIZE_4KB !! 665 config HAVE_COPY_THREAD_TLS
1146 bool <<
1147 <<
1148 config HAVE_PAGE_SIZE_8KB <<
1149 bool <<
1150 <<
1151 config HAVE_PAGE_SIZE_16KB <<
1152 bool <<
1153 <<
1154 config HAVE_PAGE_SIZE_32KB <<
1155 bool <<
1156 <<
1157 config HAVE_PAGE_SIZE_64KB <<
1158 bool 666 bool
1159 <<
1160 config HAVE_PAGE_SIZE_256KB <<
1161 bool <<
1162 <<
1163 choice <<
1164 prompt "MMU page size" <<
1165 <<
1166 config PAGE_SIZE_4KB <<
1167 bool "4KiB pages" <<
1168 depends on HAVE_PAGE_SIZE_4KB <<
1169 help <<
1170 This option select the standard 4Ki <<
1171 available option on many architectu <<
1172 minimize memory consumption and is <<
1173 memory systems. <<
1174 Some software that is written for x <<
1175 assumptions about the page size and <<
1176 <<
1177 config PAGE_SIZE_8KB <<
1178 bool "8KiB pages" <<
1179 depends on HAVE_PAGE_SIZE_8KB <<
1180 help <<
1181 This option is the only supported p <<
1182 processors, and can be slightly fas <<
1183 <<
1184 config PAGE_SIZE_16KB <<
1185 bool "16KiB pages" <<
1186 depends on HAVE_PAGE_SIZE_16KB <<
1187 help 667 help
1188 This option is usually a good compr !! 668 Architecture provides copy_thread_tls to accept tls argument via
1189 consumption and performance for typ !! 669 normal C parameter passing, rather than extracting the syscall
1190 workloads, often saving a level of !! 670 argument from pt_regs.
1191 to 4KB pages as well as reducing TL <<
1192 per-page operations in the kernel a <<
1193 page cache. <<
1194 <<
1195 config PAGE_SIZE_32KB <<
1196 bool "32KiB pages" <<
1197 depends on HAVE_PAGE_SIZE_32KB <<
1198 help <<
1199 Using 32KiB page size will result i <<
1200 kernel at the price of higher memor <<
1201 16KiB pages. This option is availa <<
1202 Note that you will need a suitable <<
1203 support this. <<
1204 <<
1205 config PAGE_SIZE_64KB <<
1206 bool "64KiB pages" <<
1207 depends on HAVE_PAGE_SIZE_64KB <<
1208 help <<
1209 Using 64KiB page size will result i <<
1210 kernel at the price of much higher <<
1211 4KiB or 16KiB pages. <<
1212 This is not suitable for general-pu <<
1213 better performance may be worth the <<
1214 supercomputing or database applicat <<
1215 large in-memory data rather than sm <<
1216 <<
1217 config PAGE_SIZE_256KB <<
1218 bool "256KiB pages" <<
1219 depends on HAVE_PAGE_SIZE_256KB <<
1220 help <<
1221 256KiB pages have little practical <<
1222 memory usage. The kernel will only <<
1223 that have been compiled with '-zmax <<
1224 (the default is 64KiB or 4KiB on mo <<
1225 <<
1226 endchoice <<
1227 <<
1228 config PAGE_SIZE_LESS_THAN_64KB <<
1229 def_bool y <<
1230 depends on !PAGE_SIZE_64KB <<
1231 depends on PAGE_SIZE_LESS_THAN_256KB <<
1232 <<
1233 config PAGE_SIZE_LESS_THAN_256KB <<
1234 def_bool y <<
1235 depends on !PAGE_SIZE_256KB <<
1236 <<
1237 config PAGE_SHIFT <<
1238 int <<
1239 default 12 if PAGE_SIZE_4KB <<
1240 default 13 if PAGE_SIZE_8KB <<
1241 default 14 if PAGE_SIZE_16KB <<
1242 default 15 if PAGE_SIZE_32KB <<
1243 default 16 if PAGE_SIZE_64KB <<
1244 default 18 if PAGE_SIZE_256KB <<
1245 <<
1246 # This allows to use a set of generic functio <<
1247 # address by giving priority to top-down sche <<
1248 # is not in legacy mode (compat task, unlimit <<
1249 # sysctl_legacy_va_layout). <<
1250 # Architecture that selects this option can p <<
1251 # - STACK_RND_MASK <<
1252 config ARCH_WANT_DEFAULT_TOPDOWN_MMAP_LAYOUT <<
1253 bool <<
1254 depends on MMU <<
1255 select ARCH_HAS_ELF_RANDOMIZE <<
1256 <<
1257 config HAVE_OBJTOOL <<
1258 bool <<
1259 <<
1260 config HAVE_JUMP_LABEL_HACK <<
1261 bool <<
1262 <<
1263 config HAVE_NOINSTR_HACK <<
1264 bool <<
1265 <<
1266 config HAVE_NOINSTR_VALIDATION <<
1267 bool <<
1268 <<
1269 config HAVE_UACCESS_VALIDATION <<
1270 bool <<
1271 select OBJTOOL <<
1272 671
1273 config HAVE_STACK_VALIDATION 672 config HAVE_STACK_VALIDATION
1274 bool 673 bool
1275 help 674 help
1276 Architecture supports objtool compi !! 675 Architecture supports the 'objtool check' host tool command, which
1277 validation. !! 676 performs compile-time stack metadata validation.
1278 677
1279 config HAVE_RELIABLE_STACKTRACE 678 config HAVE_RELIABLE_STACKTRACE
1280 bool 679 bool
1281 help 680 help
1282 Architecture has either save_stack_ !! 681 Architecture has a save_stack_trace_tsk_reliable() function which
1283 arch_stack_walk_reliable() function !! 682 only returns a stack trace if it can guarantee the trace is reliable.
1284 if it can guarantee the trace is re <<
1285 683
1286 config HAVE_ARCH_HASH 684 config HAVE_ARCH_HASH
1287 bool 685 bool
1288 default n 686 default n
1289 help 687 help
1290 If this is set, the architecture pr 688 If this is set, the architecture provides an <asm/hash.h>
1291 file which provides platform-specif 689 file which provides platform-specific implementations of some
1292 functions in <linux/hash.h> or fs/n 690 functions in <linux/hash.h> or fs/namei.c.
1293 691
1294 config HAVE_ARCH_NVRAM_OPS <<
1295 bool <<
1296 <<
1297 config ISA_BUS_API 692 config ISA_BUS_API
1298 def_bool ISA 693 def_bool ISA
1299 694
1300 # 695 #
1301 # ABI hall of shame 696 # ABI hall of shame
1302 # 697 #
1303 config CLONE_BACKWARDS 698 config CLONE_BACKWARDS
1304 bool 699 bool
1305 help 700 help
1306 Architecture has tls passed as the 701 Architecture has tls passed as the 4th argument of clone(2),
1307 not the 5th one. 702 not the 5th one.
1308 703
1309 config CLONE_BACKWARDS2 704 config CLONE_BACKWARDS2
1310 bool 705 bool
1311 help 706 help
1312 Architecture has the first two argu 707 Architecture has the first two arguments of clone(2) swapped.
1313 708
1314 config CLONE_BACKWARDS3 709 config CLONE_BACKWARDS3
1315 bool 710 bool
1316 help 711 help
1317 Architecture has tls passed as the 712 Architecture has tls passed as the 3rd argument of clone(2),
1318 not the 5th one. 713 not the 5th one.
1319 714
1320 config ODD_RT_SIGACTION 715 config ODD_RT_SIGACTION
1321 bool 716 bool
1322 help 717 help
1323 Architecture has unusual rt_sigacti 718 Architecture has unusual rt_sigaction(2) arguments
1324 719
1325 config OLD_SIGSUSPEND 720 config OLD_SIGSUSPEND
1326 bool 721 bool
1327 help 722 help
1328 Architecture has old sigsuspend(2) 723 Architecture has old sigsuspend(2) syscall, of one-argument variety
1329 724
1330 config OLD_SIGSUSPEND3 725 config OLD_SIGSUSPEND3
1331 bool 726 bool
1332 help 727 help
1333 Even weirder antique ABI - three-ar 728 Even weirder antique ABI - three-argument sigsuspend(2)
1334 729
1335 config OLD_SIGACTION 730 config OLD_SIGACTION
1336 bool 731 bool
1337 help 732 help
1338 Architecture has old sigaction(2) s 733 Architecture has old sigaction(2) syscall. Nope, not the same
1339 as OLD_SIGSUSPEND | OLD_SIGSUSPEND3 734 as OLD_SIGSUSPEND | OLD_SIGSUSPEND3 - alpha has sigsuspend(2),
1340 but fairly different variant of sig 735 but fairly different variant of sigaction(2), thanks to OSF/1
1341 compatibility... 736 compatibility...
1342 737
1343 config COMPAT_OLD_SIGACTION 738 config COMPAT_OLD_SIGACTION
1344 bool 739 bool
1345 740
>> 741 config 64BIT_TIME
>> 742 def_bool ARCH_HAS_64BIT_TIME
>> 743 help
>> 744 This should be selected by all architectures that need to support
>> 745 new system calls with a 64-bit time_t. This is relevant on all 32-bit
>> 746 architectures, and 64-bit architectures as part of compat syscall
>> 747 handling.
>> 748
1346 config COMPAT_32BIT_TIME 749 config COMPAT_32BIT_TIME
1347 bool "Provide system calls for 32-bit !! 750 def_bool (!64BIT && 64BIT_TIME) || COMPAT
1348 default !64BIT || COMPAT <<
1349 help 751 help
1350 This enables 32 bit time_t support 752 This enables 32 bit time_t support in addition to 64 bit time_t support.
1351 This is relevant on all 32-bit arch 753 This is relevant on all 32-bit architectures, and 64-bit architectures
1352 as part of compat syscall handling. 754 as part of compat syscall handling.
1353 755
1354 config ARCH_NO_PREEMPT !! 756 config ARCH_NO_COHERENT_DMA_MMAP
1355 bool 757 bool
1356 758
1357 config ARCH_SUPPORTS_RT !! 759 config ARCH_NO_PREEMPT
1358 bool 760 bool
1359 761
1360 config CPU_NO_EFFICIENT_FFS 762 config CPU_NO_EFFICIENT_FFS
1361 def_bool n 763 def_bool n
1362 764
1363 config HAVE_ARCH_VMAP_STACK 765 config HAVE_ARCH_VMAP_STACK
1364 def_bool n 766 def_bool n
1365 help 767 help
1366 An arch should select this symbol i 768 An arch should select this symbol if it can support kernel stacks
1367 in vmalloc space. This means: 769 in vmalloc space. This means:
1368 770
1369 - vmalloc space must be large enoug 771 - vmalloc space must be large enough to hold many kernel stacks.
1370 This may rule out many 32-bit arc 772 This may rule out many 32-bit architectures.
1371 773
1372 - Stacks in vmalloc space need to w 774 - Stacks in vmalloc space need to work reliably. For example, if
1373 vmap page tables are created on d 775 vmap page tables are created on demand, either this mechanism
1374 needs to work while the stack poi 776 needs to work while the stack points to a virtual address with
1375 unpopulated page tables or arch c 777 unpopulated page tables or arch code (switch_to() and switch_mm(),
1376 most likely) needs to ensure that 778 most likely) needs to ensure that the stack's page table entries
1377 are populated before running on a 779 are populated before running on a possibly unpopulated stack.
1378 780
1379 - If the stack overflows into a gua 781 - If the stack overflows into a guard page, something reasonable
1380 should happen. The definition of 782 should happen. The definition of "reasonable" is flexible, but
1381 instantly rebooting without loggi 783 instantly rebooting without logging anything would be unfriendly.
1382 784
1383 config VMAP_STACK 785 config VMAP_STACK
1384 default y 786 default y
1385 bool "Use a virtually-mapped stack" 787 bool "Use a virtually-mapped stack"
1386 depends on HAVE_ARCH_VMAP_STACK !! 788 depends on HAVE_ARCH_VMAP_STACK && !KASAN
1387 depends on !KASAN || KASAN_HW_TAGS || !! 789 ---help---
1388 help <<
1389 Enable this if you want the use vir 790 Enable this if you want the use virtually-mapped kernel stacks
1390 with guard pages. This causes kern 791 with guard pages. This causes kernel stack overflows to be
1391 caught immediately rather than caus 792 caught immediately rather than causing difficult-to-diagnose
1392 corruption. 793 corruption.
1393 794
1394 To use this with software KASAN mod !! 795 This is presently incompatible with KASAN because KASAN expects
1395 backing virtual mappings with real !! 796 the stack to map directly to the KASAN shadow map using a formula
1396 must be enabled. !! 797 that is incorrect if the stack is in vmalloc space.
1397 <<
1398 config HAVE_ARCH_RANDOMIZE_KSTACK_OFFSET <<
1399 def_bool n <<
1400 help <<
1401 An arch should select this symbol i <<
1402 offset randomization with calls to <<
1403 during syscall entry and choose_ran <<
1404 syscall exit. Careful removal of -f <<
1405 -fstack-protector should also be ap <<
1406 closely examined, as the artificial <<
1407 to the compiler, so it will attempt <<
1408 of the static branch state. <<
1409 <<
1410 config RANDOMIZE_KSTACK_OFFSET <<
1411 bool "Support for randomizing kernel <<
1412 default y <<
1413 depends on HAVE_ARCH_RANDOMIZE_KSTACK <<
1414 depends on INIT_STACK_NONE || !CC_IS_ <<
1415 help <<
1416 The kernel stack offset can be rand <<
1417 roughly 5 bits of entropy, frustrat <<
1418 attacks that depend on stack addres <<
1419 cross-syscall address exposures. <<
1420 <<
1421 The feature is controlled via the " <<
1422 kernel boot param, and if turned of <<
1423 of static branches (see JUMP_LABEL) <<
1424 <<
1425 If unsure, say Y. <<
1426 <<
1427 config RANDOMIZE_KSTACK_OFFSET_DEFAULT <<
1428 bool "Default state of kernel stack o <<
1429 depends on RANDOMIZE_KSTACK_OFFSET <<
1430 help <<
1431 Kernel stack offset randomization i <<
1432 "randomize_kstack_offset=on/off", a <<
1433 boot state. <<
1434 798
1435 config ARCH_OPTIONAL_KERNEL_RWX 799 config ARCH_OPTIONAL_KERNEL_RWX
1436 def_bool n 800 def_bool n
1437 801
1438 config ARCH_OPTIONAL_KERNEL_RWX_DEFAULT 802 config ARCH_OPTIONAL_KERNEL_RWX_DEFAULT
1439 def_bool n 803 def_bool n
1440 804
1441 config ARCH_HAS_STRICT_KERNEL_RWX 805 config ARCH_HAS_STRICT_KERNEL_RWX
1442 def_bool n 806 def_bool n
1443 807
1444 config STRICT_KERNEL_RWX 808 config STRICT_KERNEL_RWX
1445 bool "Make kernel text and rodata rea 809 bool "Make kernel text and rodata read-only" if ARCH_OPTIONAL_KERNEL_RWX
1446 depends on ARCH_HAS_STRICT_KERNEL_RWX 810 depends on ARCH_HAS_STRICT_KERNEL_RWX
1447 default !ARCH_OPTIONAL_KERNEL_RWX || 811 default !ARCH_OPTIONAL_KERNEL_RWX || ARCH_OPTIONAL_KERNEL_RWX_DEFAULT
1448 help 812 help
1449 If this is set, kernel text and rod 813 If this is set, kernel text and rodata memory will be made read-only,
1450 and non-text memory will be made no 814 and non-text memory will be made non-executable. This provides
1451 protection against certain security 815 protection against certain security exploits (e.g. executing the heap
1452 or modifying text) 816 or modifying text)
1453 817
1454 These features are considered stand 818 These features are considered standard security practice these days.
1455 You should say Y here in almost all 819 You should say Y here in almost all cases.
1456 820
1457 config ARCH_HAS_STRICT_MODULE_RWX 821 config ARCH_HAS_STRICT_MODULE_RWX
1458 def_bool n 822 def_bool n
1459 823
1460 config STRICT_MODULE_RWX 824 config STRICT_MODULE_RWX
1461 bool "Set loadable kernel module data 825 bool "Set loadable kernel module data as NX and text as RO" if ARCH_OPTIONAL_KERNEL_RWX
1462 depends on ARCH_HAS_STRICT_MODULE_RWX 826 depends on ARCH_HAS_STRICT_MODULE_RWX && MODULES
1463 default !ARCH_OPTIONAL_KERNEL_RWX || 827 default !ARCH_OPTIONAL_KERNEL_RWX || ARCH_OPTIONAL_KERNEL_RWX_DEFAULT
1464 help 828 help
1465 If this is set, module text and rod 829 If this is set, module text and rodata memory will be made read-only,
1466 and non-text memory will be made no 830 and non-text memory will be made non-executable. This provides
1467 protection against certain security 831 protection against certain security exploits (e.g. writing to text)
1468 832
1469 # select if the architecture provides an asm/ 833 # select if the architecture provides an asm/dma-direct.h header
1470 config ARCH_HAS_PHYS_TO_DMA 834 config ARCH_HAS_PHYS_TO_DMA
1471 bool 835 bool
1472 836
>> 837 config ARCH_HAS_REFCOUNT
>> 838 bool
>> 839 help
>> 840 An architecture selects this when it has implemented refcount_t
>> 841 using open coded assembly primitives that provide an optimized
>> 842 refcount_t implementation, possibly at the expense of some full
>> 843 refcount state checks of CONFIG_REFCOUNT_FULL=y.
>> 844
>> 845 The refcount overflow check behavior, however, must be retained.
>> 846 Catching overflows is the primary security concern for protecting
>> 847 against bugs in reference counts.
>> 848
>> 849 config REFCOUNT_FULL
>> 850 bool "Perform full reference count validation at the expense of speed"
>> 851 help
>> 852 Enabling this switches the refcounting infrastructure from a fast
>> 853 unchecked atomic_t implementation to a fully state checked
>> 854 implementation, which can be (slightly) slower but provides protections
>> 855 against various use-after-free conditions that can be used in
>> 856 security flaw exploits.
>> 857
1473 config HAVE_ARCH_COMPILER_H 858 config HAVE_ARCH_COMPILER_H
1474 bool 859 bool
1475 help 860 help
1476 An architecture can select this if 861 An architecture can select this if it provides an
1477 asm/compiler.h header that should b 862 asm/compiler.h header that should be included after
1478 linux/compiler-*.h in order to over 863 linux/compiler-*.h in order to override macro definitions that those
1479 headers generally provide. 864 headers generally provide.
1480 865
1481 config HAVE_ARCH_PREL32_RELOCATIONS 866 config HAVE_ARCH_PREL32_RELOCATIONS
1482 bool 867 bool
1483 help 868 help
1484 May be selected by an architecture 869 May be selected by an architecture if it supports place-relative
1485 32-bit relocations, both in the too 870 32-bit relocations, both in the toolchain and in the module loader,
1486 in which case relative references c 871 in which case relative references can be used in special sections
1487 for PCI fixup, initcalls etc which 872 for PCI fixup, initcalls etc which are only half the size on 64 bit
1488 architectures, and don't require ru 873 architectures, and don't require runtime relocation on relocatable
1489 kernels. 874 kernels.
1490 875
1491 config ARCH_USE_MEMREMAP_PROT 876 config ARCH_USE_MEMREMAP_PROT
1492 bool 877 bool
1493 878
1494 config LOCK_EVENT_COUNTS <<
1495 bool "Locking event counts collection <<
1496 depends on DEBUG_FS <<
1497 help <<
1498 Enable light-weight counting of var <<
1499 in the system with minimal performa <<
1500 the chance of application behavior <<
1501 differences. The counts are reporte <<
1502 <<
1503 # Select if the architecture has support for <<
1504 config ARCH_HAS_RELR <<
1505 bool <<
1506 <<
1507 config RELR <<
1508 bool "Use RELR relocation packing" <<
1509 depends on ARCH_HAS_RELR && TOOLS_SUP <<
1510 default y <<
1511 help <<
1512 Store the kernel's dynamic relocati <<
1513 format. Requires a compatible linke <<
1514 well as compatible NM and OBJCOPY u <<
1515 are compatible). <<
1516 <<
1517 config ARCH_HAS_MEM_ENCRYPT <<
1518 bool <<
1519 <<
1520 config ARCH_HAS_CC_PLATFORM <<
1521 bool <<
1522 <<
1523 config HAVE_SPARSE_SYSCALL_NR <<
1524 bool <<
1525 help <<
1526 An architecture should select this <<
1527 to save space. For example, MIPS ar <<
1528 entries at 4000, 5000 and 6000 loca <<
1529 related optimizations for a given a <<
1530 <<
1531 config ARCH_HAS_VDSO_DATA <<
1532 bool <<
1533 <<
1534 config HAVE_STATIC_CALL <<
1535 bool <<
1536 <<
1537 config HAVE_STATIC_CALL_INLINE <<
1538 bool <<
1539 depends on HAVE_STATIC_CALL <<
1540 select OBJTOOL <<
1541 <<
1542 config HAVE_PREEMPT_DYNAMIC <<
1543 bool <<
1544 <<
1545 config HAVE_PREEMPT_DYNAMIC_CALL <<
1546 bool <<
1547 depends on HAVE_STATIC_CALL <<
1548 select HAVE_PREEMPT_DYNAMIC <<
1549 help <<
1550 An architecture should select this <<
1551 model being selected at boot time u <<
1552 <<
1553 Where an architecture selects HAVE_ <<
1554 preemption function will be patched <<
1555 <<
1556 Where an architecture does not sele <<
1557 call to a preemption function will <<
1558 trampoline will be patched. <<
1559 <<
1560 It is strongly advised to support i <<
1561 overhead. <<
1562 <<
1563 config HAVE_PREEMPT_DYNAMIC_KEY <<
1564 bool <<
1565 depends on HAVE_ARCH_JUMP_LABEL <<
1566 select HAVE_PREEMPT_DYNAMIC <<
1567 help <<
1568 An architecture should select this <<
1569 model being selected at boot time u <<
1570 <<
1571 Each preemption function will be gi <<
1572 static key. This should have slight <<
1573 static calls, as this effectively i <<
1574 start of its callee. This may avoid <<
1575 integrate better with CFI schemes. <<
1576 <<
1577 This will have greater overhead tha <<
1578 the call to the preemption function <<
1579 <<
1580 config ARCH_WANT_LD_ORPHAN_WARN <<
1581 bool <<
1582 help <<
1583 An arch should select this symbol o <<
1584 included, size-asserted, or discard <<
1585 important because we never want exp <<
1586 by the linker, since the locations <<
1587 versions. <<
1588 <<
1589 config HAVE_ARCH_PFN_VALID <<
1590 bool <<
1591 <<
1592 config ARCH_SUPPORTS_DEBUG_PAGEALLOC <<
1593 bool <<
1594 <<
1595 config ARCH_SUPPORTS_PAGE_TABLE_CHECK <<
1596 bool <<
1597 <<
1598 config ARCH_SPLIT_ARG64 <<
1599 bool <<
1600 help <<
1601 If a 32-bit architecture requires 6 <<
1602 pairs of 32-bit arguments, select t <<
1603 <<
1604 config ARCH_HAS_ELFCORE_COMPAT <<
1605 bool <<
1606 <<
1607 config ARCH_HAS_PARANOID_L1D_FLUSH <<
1608 bool <<
1609 <<
1610 config ARCH_HAVE_TRACE_MMIO_ACCESS <<
1611 bool <<
1612 <<
1613 config DYNAMIC_SIGFRAME <<
1614 bool <<
1615 <<
1616 # Select, if arch has a named attribute group <<
1617 config HAVE_ARCH_NODE_DEV_GROUP <<
1618 bool <<
1619 <<
1620 config ARCH_HAS_HW_PTE_YOUNG <<
1621 bool <<
1622 help <<
1623 Architectures that select this opti <<
1624 accessed bit in PTE entries when us <<
1625 translations. Architectures that re <<
1626 this option and override arch_has_h <<
1627 <<
1628 config ARCH_HAS_NONLEAF_PMD_YOUNG <<
1629 bool <<
1630 help <<
1631 Architectures that select this opti <<
1632 accessed bit in non-leaf PMD entrie <<
1633 address translations. Page table wa <<
1634 may use this capability to reduce t <<
1635 <<
1636 config ARCH_HAS_KERNEL_FPU_SUPPORT <<
1637 bool <<
1638 help <<
1639 Architectures that select this opti <<
1640 the kernel, as described in Documen <<
1641 <<
1642 source "kernel/gcov/Kconfig" 879 source "kernel/gcov/Kconfig"
1643 880
1644 source "scripts/gcc-plugins/Kconfig" 881 source "scripts/gcc-plugins/Kconfig"
1645 <<
1646 config FUNCTION_ALIGNMENT_4B <<
1647 bool <<
1648 <<
1649 config FUNCTION_ALIGNMENT_8B <<
1650 bool <<
1651 <<
1652 config FUNCTION_ALIGNMENT_16B <<
1653 bool <<
1654 <<
1655 config FUNCTION_ALIGNMENT_32B <<
1656 bool <<
1657 <<
1658 config FUNCTION_ALIGNMENT_64B <<
1659 bool <<
1660 <<
1661 config FUNCTION_ALIGNMENT <<
1662 int <<
1663 default 64 if FUNCTION_ALIGNMENT_64B <<
1664 default 32 if FUNCTION_ALIGNMENT_32B <<
1665 default 16 if FUNCTION_ALIGNMENT_16B <<
1666 default 8 if FUNCTION_ALIGNMENT_8B <<
1667 default 4 if FUNCTION_ALIGNMENT_4B <<
1668 default 0 <<
1669 <<
1670 config CC_HAS_MIN_FUNCTION_ALIGNMENT <<
1671 # Detect availability of the GCC opti <<
1672 # guarantees minimal alignment for al <<
1673 # -falign-functions which the compile <<
1674 def_bool $(cc-option, -fmin-function- <<
1675 <<
1676 config CC_HAS_SANE_FUNCTION_ALIGNMENT <<
1677 # Set if the guaranteed alignment wit <<
1678 # available or extra care is required <<
1679 # strict alignment always, even with <<
1680 def_bool CC_HAS_MIN_FUNCTION_ALIGNMEN <<
1681 <<
1682 config ARCH_NEED_CMPXCHG_1_EMU <<
1683 bool <<
1684 882
1685 endmenu 883 endmenu
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