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 menu "General architecture-dependent options" 12 menu "General architecture-dependent options"
21 13
22 config ARCH_HAS_SUBPAGE_FAULTS !! 14 config CRASH_CORE
23 bool <<
24 help <<
25 Select if the architecture can check <<
26 granularity (e.g. arm64 MTE). The pr <<
27 must be implemented. <<
28 <<
29 config HOTPLUG_SMT <<
30 bool <<
31 <<
32 config SMT_NUM_THREADS_DYNAMIC <<
33 bool 15 bool
34 16
35 # Selected by HOTPLUG_CORE_SYNC_DEAD or HOTPLU !! 17 config KEXEC_CORE
36 config HOTPLUG_CORE_SYNC !! 18 select CRASH_CORE
37 bool 19 bool
38 20
39 # Basic CPU dead synchronization selected by a !! 21 config KEXEC_ELF
40 config HOTPLUG_CORE_SYNC_DEAD <<
41 bool 22 bool
42 select HOTPLUG_CORE_SYNC <<
43 23
44 # Full CPU synchronization with alive state se !! 24 config HAVE_IMA_KEXEC
45 config HOTPLUG_CORE_SYNC_FULL <<
46 bool 25 bool
47 select HOTPLUG_CORE_SYNC_DEAD if HOTPL <<
48 select HOTPLUG_CORE_SYNC <<
49 26
50 config HOTPLUG_SPLIT_STARTUP !! 27 config ARCH_HAS_SUBPAGE_FAULTS
51 bool 28 bool
52 select HOTPLUG_CORE_SYNC_FULL !! 29 help
>> 30 Select if the architecture can check permissions at sub-page
>> 31 granularity (e.g. arm64 MTE). The probe_user_*() functions
>> 32 must be implemented.
53 33
54 config HOTPLUG_PARALLEL !! 34 config HOTPLUG_SMT
55 bool 35 bool
56 select HOTPLUG_SPLIT_STARTUP <<
57 36
58 config GENERIC_ENTRY 37 config GENERIC_ENTRY
59 bool 38 bool
60 39
61 config KPROBES 40 config KPROBES
62 bool "Kprobes" 41 bool "Kprobes"
>> 42 depends on MODULES
63 depends on HAVE_KPROBES 43 depends on HAVE_KPROBES
64 select KALLSYMS 44 select KALLSYMS
65 select EXECMEM !! 45 select TASKS_RCU if PREEMPTION
66 select NEED_TASKS_RCU <<
67 help 46 help
68 Kprobes allows you to trap at almost 47 Kprobes allows you to trap at almost any kernel address and
69 execute a callback function. regist 48 execute a callback function. register_kprobe() establishes
70 a probepoint and specifies the callb 49 a probepoint and specifies the callback. Kprobes is useful
71 for kernel debugging, non-intrusive 50 for kernel debugging, non-intrusive instrumentation and testing.
72 If in doubt, say "N". 51 If in doubt, say "N".
73 52
74 config JUMP_LABEL 53 config JUMP_LABEL
75 bool "Optimize very unlikely/likely br 54 bool "Optimize very unlikely/likely branches"
76 depends on HAVE_ARCH_JUMP_LABEL 55 depends on HAVE_ARCH_JUMP_LABEL
77 select OBJTOOL if HAVE_JUMP_LABEL_HACK 56 select OBJTOOL if HAVE_JUMP_LABEL_HACK
78 help 57 help
79 This option enables a transparent br 58 This option enables a transparent branch optimization that
80 makes certain almost-always-true or 59 makes certain almost-always-true or almost-always-false branch
81 conditions even cheaper to execute w 60 conditions even cheaper to execute within the kernel.
82 61
83 Certain performance-sensitive kernel 62 Certain performance-sensitive kernel code, such as trace points,
84 scheduler functionality, networking 63 scheduler functionality, networking code and KVM have such
85 branches and include support for thi 64 branches and include support for this optimization technique.
86 65
87 If it is detected that the compiler 66 If it is detected that the compiler has support for "asm goto",
88 the kernel will compile such branche 67 the kernel will compile such branches with just a nop
89 instruction. When the condition flag 68 instruction. When the condition flag is toggled to true, the
90 nop will be converted to a jump inst 69 nop will be converted to a jump instruction to execute the
91 conditional block of instructions. 70 conditional block of instructions.
92 71
93 This technique lowers overhead and s 72 This technique lowers overhead and stress on the branch prediction
94 of the processor and generally makes 73 of the processor and generally makes the kernel faster. The update
95 of the condition is slower, but thos 74 of the condition is slower, but those are always very rare.
96 75
97 ( On 32-bit x86, the necessary optio 76 ( On 32-bit x86, the necessary options added to the compiler
98 flags may increase the size of the 77 flags may increase the size of the kernel slightly. )
99 78
100 config STATIC_KEYS_SELFTEST 79 config STATIC_KEYS_SELFTEST
101 bool "Static key selftest" 80 bool "Static key selftest"
102 depends on JUMP_LABEL 81 depends on JUMP_LABEL
103 help 82 help
104 Boot time self-test of the branch pa 83 Boot time self-test of the branch patching code.
105 84
106 config STATIC_CALL_SELFTEST 85 config STATIC_CALL_SELFTEST
107 bool "Static call selftest" 86 bool "Static call selftest"
108 depends on HAVE_STATIC_CALL 87 depends on HAVE_STATIC_CALL
109 help 88 help
110 Boot time self-test of the call patc 89 Boot time self-test of the call patching code.
111 90
112 config OPTPROBES 91 config OPTPROBES
113 def_bool y 92 def_bool y
114 depends on KPROBES && HAVE_OPTPROBES 93 depends on KPROBES && HAVE_OPTPROBES
115 select NEED_TASKS_RCU !! 94 select TASKS_RCU if PREEMPTION
116 95
117 config KPROBES_ON_FTRACE 96 config KPROBES_ON_FTRACE
118 def_bool y 97 def_bool y
119 depends on KPROBES && HAVE_KPROBES_ON_ 98 depends on KPROBES && HAVE_KPROBES_ON_FTRACE
120 depends on DYNAMIC_FTRACE_WITH_REGS 99 depends on DYNAMIC_FTRACE_WITH_REGS
121 help 100 help
122 If function tracer is enabled and th 101 If function tracer is enabled and the arch supports full
123 passing of pt_regs to function traci 102 passing of pt_regs to function tracing, then kprobes can
124 optimize on top of function tracing. 103 optimize on top of function tracing.
125 104
126 config UPROBES 105 config UPROBES
127 def_bool n 106 def_bool n
128 depends on ARCH_SUPPORTS_UPROBES 107 depends on ARCH_SUPPORTS_UPROBES
129 help 108 help
130 Uprobes is the user-space counterpar 109 Uprobes is the user-space counterpart to kprobes: they
131 enable instrumentation applications 110 enable instrumentation applications (such as 'perf probe')
132 to establish unintrusive probes in u 111 to establish unintrusive probes in user-space binaries and
133 libraries, by executing handler func 112 libraries, by executing handler functions when the probes
134 are hit by user-space applications. 113 are hit by user-space applications.
135 114
136 ( These probes come in the form of s 115 ( These probes come in the form of single-byte breakpoints,
137 managed by the kernel and kept tra 116 managed by the kernel and kept transparent to the probed
138 application. ) 117 application. )
139 118
140 config HAVE_64BIT_ALIGNED_ACCESS 119 config HAVE_64BIT_ALIGNED_ACCESS
141 def_bool 64BIT && !HAVE_EFFICIENT_UNAL 120 def_bool 64BIT && !HAVE_EFFICIENT_UNALIGNED_ACCESS
142 help 121 help
143 Some architectures require 64 bit ac 122 Some architectures require 64 bit accesses to be 64 bit
144 aligned, which also requires structs 123 aligned, which also requires structs containing 64 bit values
145 to be 64 bit aligned too. This inclu 124 to be 64 bit aligned too. This includes some 32 bit
146 architectures which can do 64 bit ac 125 architectures which can do 64 bit accesses, as well as 64 bit
147 architectures without unaligned acce 126 architectures without unaligned access.
148 127
149 This symbol should be selected by an 128 This symbol should be selected by an architecture if 64 bit
150 accesses are required to be 64 bit a 129 accesses are required to be 64 bit aligned in this way even
151 though it is not a 64 bit architectu 130 though it is not a 64 bit architecture.
152 131
153 See Documentation/core-api/unaligned 132 See Documentation/core-api/unaligned-memory-access.rst for
154 more information on the topic of una 133 more information on the topic of unaligned memory accesses.
155 134
156 config HAVE_EFFICIENT_UNALIGNED_ACCESS 135 config HAVE_EFFICIENT_UNALIGNED_ACCESS
157 bool 136 bool
158 help 137 help
159 Some architectures are unable to per 138 Some architectures are unable to perform unaligned accesses
160 without the use of get_unaligned/put 139 without the use of get_unaligned/put_unaligned. Others are
161 unable to perform such accesses effi 140 unable to perform such accesses efficiently (e.g. trap on
162 unaligned access and require fixing 141 unaligned access and require fixing it up in the exception
163 handler.) 142 handler.)
164 143
165 This symbol should be selected by an 144 This symbol should be selected by an architecture if it can
166 perform unaligned accesses efficient 145 perform unaligned accesses efficiently to allow different
167 code paths to be selected for these 146 code paths to be selected for these cases. Some network
168 drivers, for example, could opt to n 147 drivers, for example, could opt to not fix up alignment
169 problems with received packets if do 148 problems with received packets if doing so would not help
170 much. 149 much.
171 150
172 See Documentation/core-api/unaligned 151 See Documentation/core-api/unaligned-memory-access.rst for more
173 information on the topic of unaligne 152 information on the topic of unaligned memory accesses.
174 153
175 config ARCH_USE_BUILTIN_BSWAP 154 config ARCH_USE_BUILTIN_BSWAP
176 bool 155 bool
177 help 156 help
178 Modern versions of GCC (since 4.4) h 157 Modern versions of GCC (since 4.4) have builtin functions
179 for handling byte-swapping. Using th 158 for handling byte-swapping. Using these, instead of the old
180 inline assembler that the architectu 159 inline assembler that the architecture code provides in the
181 __arch_bswapXX() macros, allows the 160 __arch_bswapXX() macros, allows the compiler to see what's
182 happening and offers more opportunit 161 happening and offers more opportunity for optimisation. In
183 particular, the compiler will be abl 162 particular, the compiler will be able to combine the byteswap
184 with a nearby load or store and use 163 with a nearby load or store and use load-and-swap or
185 store-and-swap instructions if the a 164 store-and-swap instructions if the architecture has them. It
186 should almost *never* result in code 165 should almost *never* result in code which is worse than the
187 hand-coded assembler in <asm/swab.h> 166 hand-coded assembler in <asm/swab.h>. But just in case it
188 does, the use of the builtins is opt 167 does, the use of the builtins is optional.
189 168
190 Any architecture with load-and-swap 169 Any architecture with load-and-swap or store-and-swap
191 instructions should set this. And it 170 instructions should set this. And it shouldn't hurt to set it
192 on architectures that don't have suc 171 on architectures that don't have such instructions.
193 172
194 config KRETPROBES 173 config KRETPROBES
195 def_bool y 174 def_bool y
196 depends on KPROBES && (HAVE_KRETPROBES 175 depends on KPROBES && (HAVE_KRETPROBES || HAVE_RETHOOK)
197 176
198 config KRETPROBE_ON_RETHOOK 177 config KRETPROBE_ON_RETHOOK
199 def_bool y 178 def_bool y
200 depends on HAVE_RETHOOK 179 depends on HAVE_RETHOOK
201 depends on KRETPROBES 180 depends on KRETPROBES
202 select RETHOOK 181 select RETHOOK
203 182
204 config USER_RETURN_NOTIFIER 183 config USER_RETURN_NOTIFIER
205 bool 184 bool
206 depends on HAVE_USER_RETURN_NOTIFIER 185 depends on HAVE_USER_RETURN_NOTIFIER
207 help 186 help
208 Provide a kernel-internal notificati 187 Provide a kernel-internal notification when a cpu is about to
209 switch to user mode. 188 switch to user mode.
210 189
211 config HAVE_IOREMAP_PROT 190 config HAVE_IOREMAP_PROT
212 bool 191 bool
213 192
214 config HAVE_KPROBES 193 config HAVE_KPROBES
215 bool 194 bool
216 195
217 config HAVE_KRETPROBES 196 config HAVE_KRETPROBES
218 bool 197 bool
219 198
220 config HAVE_OPTPROBES 199 config HAVE_OPTPROBES
221 bool 200 bool
222 201
223 config HAVE_KPROBES_ON_FTRACE 202 config HAVE_KPROBES_ON_FTRACE
224 bool 203 bool
225 204
226 config ARCH_CORRECT_STACKTRACE_ON_KRETPROBE 205 config ARCH_CORRECT_STACKTRACE_ON_KRETPROBE
227 bool 206 bool
228 help 207 help
229 Since kretprobes modifies return add 208 Since kretprobes modifies return address on the stack, the
230 stacktrace may see the kretprobe tra 209 stacktrace may see the kretprobe trampoline address instead
231 of correct one. If the architecture 210 of correct one. If the architecture stacktrace code and
232 unwinder can adjust such entries, se 211 unwinder can adjust such entries, select this configuration.
233 212
234 config HAVE_FUNCTION_ERROR_INJECTION 213 config HAVE_FUNCTION_ERROR_INJECTION
235 bool 214 bool
236 215
237 config HAVE_NMI 216 config HAVE_NMI
238 bool 217 bool
239 218
240 config HAVE_FUNCTION_DESCRIPTORS 219 config HAVE_FUNCTION_DESCRIPTORS
241 bool 220 bool
242 221
243 config TRACE_IRQFLAGS_SUPPORT 222 config TRACE_IRQFLAGS_SUPPORT
244 bool 223 bool
245 224
246 config TRACE_IRQFLAGS_NMI_SUPPORT 225 config TRACE_IRQFLAGS_NMI_SUPPORT
247 bool 226 bool
248 227
249 # 228 #
250 # An arch should select this if it provides al 229 # An arch should select this if it provides all these things:
251 # 230 #
252 # task_pt_regs() in asm/process 231 # task_pt_regs() in asm/processor.h or asm/ptrace.h
253 # arch_has_single_step() if there is ha 232 # arch_has_single_step() if there is hardware single-step support
254 # arch_has_block_step() if there is ha 233 # arch_has_block_step() if there is hardware block-step support
255 # asm/syscall.h supplying asm- 234 # asm/syscall.h supplying asm-generic/syscall.h interface
256 # linux/regset.h user_regset in 235 # linux/regset.h user_regset interfaces
257 # CORE_DUMP_USE_REGSET #define'd in l 236 # CORE_DUMP_USE_REGSET #define'd in linux/elf.h
258 # TIF_SYSCALL_TRACE calls ptrace_r 237 # TIF_SYSCALL_TRACE calls ptrace_report_syscall_{entry,exit}
259 # TIF_NOTIFY_RESUME calls resume_u 238 # TIF_NOTIFY_RESUME calls resume_user_mode_work()
260 # 239 #
261 config HAVE_ARCH_TRACEHOOK 240 config HAVE_ARCH_TRACEHOOK
262 bool 241 bool
263 242
264 config HAVE_DMA_CONTIGUOUS 243 config HAVE_DMA_CONTIGUOUS
265 bool 244 bool
266 245
267 config GENERIC_SMP_IDLE_THREAD 246 config GENERIC_SMP_IDLE_THREAD
268 bool 247 bool
269 248
270 config GENERIC_IDLE_POLL_SETUP 249 config GENERIC_IDLE_POLL_SETUP
271 bool 250 bool
272 251
273 config ARCH_HAS_FORTIFY_SOURCE 252 config ARCH_HAS_FORTIFY_SOURCE
274 bool 253 bool
275 help 254 help
276 An architecture should select this w 255 An architecture should select this when it can successfully
277 build and run with CONFIG_FORTIFY_SO 256 build and run with CONFIG_FORTIFY_SOURCE.
278 257
279 # 258 #
280 # Select if the arch provides a historic keepi 259 # Select if the arch provides a historic keepinit alias for the retain_initrd
281 # command line option 260 # command line option
282 # 261 #
283 config ARCH_HAS_KEEPINITRD 262 config ARCH_HAS_KEEPINITRD
284 bool 263 bool
285 264
286 # Select if arch has all set_memory_ro/rw/x/nx 265 # Select if arch has all set_memory_ro/rw/x/nx() functions in asm/cacheflush.h
287 config ARCH_HAS_SET_MEMORY 266 config ARCH_HAS_SET_MEMORY
288 bool 267 bool
289 268
290 # Select if arch has all set_direct_map_invali 269 # Select if arch has all set_direct_map_invalid/default() functions
291 config ARCH_HAS_SET_DIRECT_MAP 270 config ARCH_HAS_SET_DIRECT_MAP
292 bool 271 bool
293 272
294 # 273 #
295 # Select if the architecture provides the arch 274 # Select if the architecture provides the arch_dma_set_uncached symbol to
296 # either provide an uncached segment alias for 275 # either provide an uncached segment alias for a DMA allocation, or
297 # to remap the page tables in place. 276 # to remap the page tables in place.
298 # 277 #
299 config ARCH_HAS_DMA_SET_UNCACHED 278 config ARCH_HAS_DMA_SET_UNCACHED
300 bool 279 bool
301 280
302 # 281 #
303 # Select if the architectures provides the arc 282 # Select if the architectures provides the arch_dma_clear_uncached symbol
304 # to undo an in-place page table remap for unc 283 # to undo an in-place page table remap for uncached access.
305 # 284 #
306 config ARCH_HAS_DMA_CLEAR_UNCACHED 285 config ARCH_HAS_DMA_CLEAR_UNCACHED
307 bool 286 bool
308 287
309 config ARCH_HAS_CPU_FINALIZE_INIT 288 config ARCH_HAS_CPU_FINALIZE_INIT
310 bool 289 bool
311 290
312 # The architecture has a per-task state that i !! 291 # Select if arch init_task must go in the __init_task_data section
313 config ARCH_HAS_CPU_PASID !! 292 config ARCH_TASK_STRUCT_ON_STACK
>> 293 bool
>> 294
>> 295 # Select if arch has its private alloc_task_struct() function
>> 296 config ARCH_TASK_STRUCT_ALLOCATOR
314 bool 297 bool
315 select IOMMU_MM_DATA <<
316 298
317 config HAVE_ARCH_THREAD_STRUCT_WHITELIST 299 config HAVE_ARCH_THREAD_STRUCT_WHITELIST
318 bool 300 bool
>> 301 depends on !ARCH_TASK_STRUCT_ALLOCATOR
319 help 302 help
320 An architecture should select this t 303 An architecture should select this to provide hardened usercopy
321 knowledge about what region of the t 304 knowledge about what region of the thread_struct should be
322 whitelisted for copying to userspace 305 whitelisted for copying to userspace. Normally this is only the
323 FPU registers. Specifically, arch_th 306 FPU registers. Specifically, arch_thread_struct_whitelist()
324 should be implemented. Without this, 307 should be implemented. Without this, the entire thread_struct
325 field in task_struct will be left wh 308 field in task_struct will be left whitelisted.
326 309
>> 310 # Select if arch has its private alloc_thread_stack() function
>> 311 config ARCH_THREAD_STACK_ALLOCATOR
>> 312 bool
>> 313
327 # Select if arch wants to size task_struct dyn 314 # Select if arch wants to size task_struct dynamically via arch_task_struct_size:
328 config ARCH_WANTS_DYNAMIC_TASK_STRUCT 315 config ARCH_WANTS_DYNAMIC_TASK_STRUCT
329 bool 316 bool
330 317
331 config ARCH_WANTS_NO_INSTR 318 config ARCH_WANTS_NO_INSTR
332 bool 319 bool
333 help 320 help
334 An architecture should select this i 321 An architecture should select this if the noinstr macro is being used on
335 functions to denote that the toolcha 322 functions to denote that the toolchain should avoid instrumenting such
336 functions and is required for correc 323 functions and is required for correctness.
337 324
338 config ARCH_32BIT_OFF_T 325 config ARCH_32BIT_OFF_T
339 bool 326 bool
340 depends on !64BIT 327 depends on !64BIT
341 help 328 help
342 All new 32-bit architectures should 329 All new 32-bit architectures should have 64-bit off_t type on
343 userspace side which corresponds to 330 userspace side which corresponds to the loff_t kernel type. This
344 is the requirement for modern ABIs. 331 is the requirement for modern ABIs. Some existing architectures
345 still support 32-bit off_t. This opt 332 still support 32-bit off_t. This option is enabled for all such
346 architectures explicitly. 333 architectures explicitly.
347 334
348 # Selected by 64 bit architectures which have 335 # Selected by 64 bit architectures which have a 32 bit f_tinode in struct ustat
349 config ARCH_32BIT_USTAT_F_TINODE 336 config ARCH_32BIT_USTAT_F_TINODE
350 bool 337 bool
351 338
352 config HAVE_ASM_MODVERSIONS 339 config HAVE_ASM_MODVERSIONS
353 bool 340 bool
354 help 341 help
355 This symbol should be selected by an 342 This symbol should be selected by an architecture if it provides
356 <asm/asm-prototypes.h> to support th 343 <asm/asm-prototypes.h> to support the module versioning for symbols
357 exported from assembly code. 344 exported from assembly code.
358 345
359 config HAVE_REGS_AND_STACK_ACCESS_API 346 config HAVE_REGS_AND_STACK_ACCESS_API
360 bool 347 bool
361 help 348 help
362 This symbol should be selected by an 349 This symbol should be selected by an architecture if it supports
363 the API needed to access registers a 350 the API needed to access registers and stack entries from pt_regs,
364 declared in asm/ptrace.h 351 declared in asm/ptrace.h
365 For example the kprobes-based event 352 For example the kprobes-based event tracer needs this API.
366 353
367 config HAVE_RSEQ 354 config HAVE_RSEQ
368 bool 355 bool
369 depends on HAVE_REGS_AND_STACK_ACCESS_ 356 depends on HAVE_REGS_AND_STACK_ACCESS_API
370 help 357 help
371 This symbol should be selected by an 358 This symbol should be selected by an architecture if it
372 supports an implementation of restar 359 supports an implementation of restartable sequences.
373 360
374 config HAVE_RUST 361 config HAVE_RUST
375 bool 362 bool
376 help 363 help
377 This symbol should be selected by an 364 This symbol should be selected by an architecture if it
378 supports Rust. 365 supports Rust.
379 366
380 config HAVE_FUNCTION_ARG_ACCESS_API 367 config HAVE_FUNCTION_ARG_ACCESS_API
381 bool 368 bool
382 help 369 help
383 This symbol should be selected by an 370 This symbol should be selected by an architecture if it supports
384 the API needed to access function ar 371 the API needed to access function arguments from pt_regs,
385 declared in asm/ptrace.h 372 declared in asm/ptrace.h
386 373
387 config HAVE_HW_BREAKPOINT 374 config HAVE_HW_BREAKPOINT
388 bool 375 bool
389 depends on PERF_EVENTS 376 depends on PERF_EVENTS
390 377
391 config HAVE_MIXED_BREAKPOINTS_REGS 378 config HAVE_MIXED_BREAKPOINTS_REGS
392 bool 379 bool
393 depends on HAVE_HW_BREAKPOINT 380 depends on HAVE_HW_BREAKPOINT
394 help 381 help
395 Depending on the arch implementation 382 Depending on the arch implementation of hardware breakpoints,
396 some of them have separate registers 383 some of them have separate registers for data and instruction
397 breakpoints addresses, others have m 384 breakpoints addresses, others have mixed registers to store
398 them but define the access type in a 385 them but define the access type in a control register.
399 Select this option if your arch impl 386 Select this option if your arch implements breakpoints under the
400 latter fashion. 387 latter fashion.
401 388
402 config HAVE_USER_RETURN_NOTIFIER 389 config HAVE_USER_RETURN_NOTIFIER
403 bool 390 bool
404 391
405 config HAVE_PERF_EVENTS_NMI 392 config HAVE_PERF_EVENTS_NMI
406 bool 393 bool
407 help 394 help
408 System hardware can generate an NMI 395 System hardware can generate an NMI using the perf event
409 subsystem. Also has support for cal 396 subsystem. Also has support for calculating CPU cycle events
410 to determine how many clock cycles i 397 to determine how many clock cycles in a given period.
411 398
412 config HAVE_HARDLOCKUP_DETECTOR_PERF 399 config HAVE_HARDLOCKUP_DETECTOR_PERF
413 bool 400 bool
414 depends on HAVE_PERF_EVENTS_NMI 401 depends on HAVE_PERF_EVENTS_NMI
415 help 402 help
416 The arch chooses to use the generic 403 The arch chooses to use the generic perf-NMI-based hardlockup
417 detector. Must define HAVE_PERF_EVEN 404 detector. Must define HAVE_PERF_EVENTS_NMI.
418 405
419 config HAVE_HARDLOCKUP_DETECTOR_ARCH !! 406 config HAVE_NMI_WATCHDOG
>> 407 depends on HAVE_NMI
420 bool 408 bool
421 help 409 help
422 The arch provides its own hardlockup !! 410 The arch provides a low level NMI watchdog. It provides
423 of the generic ones. !! 411 asm/nmi.h, and defines its own arch_touch_nmi_watchdog().
424 412
425 It uses the same command line parame !! 413 config HAVE_HARDLOCKUP_DETECTOR_ARCH
426 as the generic hardlockup detectors. !! 414 bool
>> 415 select HAVE_NMI_WATCHDOG
>> 416 help
>> 417 The arch chooses to provide its own hardlockup detector, which is
>> 418 a superset of the HAVE_NMI_WATCHDOG. It also conforms to config
>> 419 interfaces and parameters provided by hardlockup detector subsystem.
427 420
428 config HAVE_PERF_REGS 421 config HAVE_PERF_REGS
429 bool 422 bool
430 help 423 help
431 Support selective register dumps for 424 Support selective register dumps for perf events. This includes
432 bit-mapping of each registers and a 425 bit-mapping of each registers and a unique architecture id.
433 426
434 config HAVE_PERF_USER_STACK_DUMP 427 config HAVE_PERF_USER_STACK_DUMP
435 bool 428 bool
436 help 429 help
437 Support user stack dumps for perf ev 430 Support user stack dumps for perf event samples. This needs
438 access to the user stack pointer whi 431 access to the user stack pointer which is not unified across
439 architectures. 432 architectures.
440 433
441 config HAVE_ARCH_JUMP_LABEL 434 config HAVE_ARCH_JUMP_LABEL
442 bool 435 bool
443 436
444 config HAVE_ARCH_JUMP_LABEL_RELATIVE 437 config HAVE_ARCH_JUMP_LABEL_RELATIVE
445 bool 438 bool
446 439
447 config MMU_GATHER_TABLE_FREE 440 config MMU_GATHER_TABLE_FREE
448 bool 441 bool
449 442
450 config MMU_GATHER_RCU_TABLE_FREE 443 config MMU_GATHER_RCU_TABLE_FREE
451 bool 444 bool
452 select MMU_GATHER_TABLE_FREE 445 select MMU_GATHER_TABLE_FREE
453 446
454 config MMU_GATHER_PAGE_SIZE 447 config MMU_GATHER_PAGE_SIZE
455 bool 448 bool
456 449
457 config MMU_GATHER_NO_RANGE 450 config MMU_GATHER_NO_RANGE
458 bool 451 bool
459 select MMU_GATHER_MERGE_VMAS 452 select MMU_GATHER_MERGE_VMAS
460 453
461 config MMU_GATHER_NO_FLUSH_CACHE 454 config MMU_GATHER_NO_FLUSH_CACHE
462 bool 455 bool
463 456
464 config MMU_GATHER_MERGE_VMAS 457 config MMU_GATHER_MERGE_VMAS
465 bool 458 bool
466 459
467 config MMU_GATHER_NO_GATHER 460 config MMU_GATHER_NO_GATHER
468 bool 461 bool
469 depends on MMU_GATHER_TABLE_FREE 462 depends on MMU_GATHER_TABLE_FREE
470 463
471 config ARCH_WANT_IRQS_OFF_ACTIVATE_MM 464 config ARCH_WANT_IRQS_OFF_ACTIVATE_MM
472 bool 465 bool
473 help 466 help
474 Temporary select until all architect 467 Temporary select until all architectures can be converted to have
475 irqs disabled over activate_mm. Arch 468 irqs disabled over activate_mm. Architectures that do IPI based TLB
476 shootdowns should enable this. 469 shootdowns should enable this.
477 470
478 # Use normal mm refcounting for MMU_LAZY_TLB k 471 # Use normal mm refcounting for MMU_LAZY_TLB kernel thread references.
479 # MMU_LAZY_TLB_REFCOUNT=n can improve the scal 472 # MMU_LAZY_TLB_REFCOUNT=n can improve the scalability of context switching
480 # to/from kernel threads when the same mm is r 473 # to/from kernel threads when the same mm is running on a lot of CPUs (a large
481 # multi-threaded application), by reducing con 474 # multi-threaded application), by reducing contention on the mm refcount.
482 # 475 #
483 # This can be disabled if the architecture ens 476 # This can be disabled if the architecture ensures no CPUs are using an mm as a
484 # "lazy tlb" beyond its final refcount (i.e., 477 # "lazy tlb" beyond its final refcount (i.e., by the time __mmdrop frees the mm
485 # or its kernel page tables). This could be ar 478 # or its kernel page tables). This could be arranged by arch_exit_mmap(), or
486 # final exit(2) TLB flush, for example. 479 # final exit(2) TLB flush, for example.
487 # 480 #
488 # To implement this, an arch *must*: 481 # To implement this, an arch *must*:
489 # Ensure the _lazy_tlb variants of mmgrab/mmdr 482 # Ensure the _lazy_tlb variants of mmgrab/mmdrop are used when manipulating
490 # the lazy tlb reference of a kthread's ->acti 483 # the lazy tlb reference of a kthread's ->active_mm (non-arch code has been
491 # converted already). 484 # converted already).
492 config MMU_LAZY_TLB_REFCOUNT 485 config MMU_LAZY_TLB_REFCOUNT
493 def_bool y 486 def_bool y
494 depends on !MMU_LAZY_TLB_SHOOTDOWN 487 depends on !MMU_LAZY_TLB_SHOOTDOWN
495 488
496 # This option allows MMU_LAZY_TLB_REFCOUNT=n. 489 # This option allows MMU_LAZY_TLB_REFCOUNT=n. It ensures no CPUs are using an
497 # mm as a lazy tlb beyond its last reference c 490 # mm as a lazy tlb beyond its last reference count, by shooting down these
498 # users before the mm is deallocated. __mmdrop 491 # users before the mm is deallocated. __mmdrop() first IPIs all CPUs that may
499 # be using the mm as a lazy tlb, so that they 492 # be using the mm as a lazy tlb, so that they may switch themselves to using
500 # init_mm for their active mm. mm_cpumask(mm) 493 # init_mm for their active mm. mm_cpumask(mm) is used to determine which CPUs
501 # may be using mm as a lazy tlb mm. 494 # may be using mm as a lazy tlb mm.
502 # 495 #
503 # To implement this, an arch *must*: 496 # To implement this, an arch *must*:
504 # - At the time of the final mmdrop of the mm, 497 # - At the time of the final mmdrop of the mm, ensure mm_cpumask(mm) contains
505 # at least all possible CPUs in which the mm 498 # at least all possible CPUs in which the mm is lazy.
506 # - It must meet the requirements for MMU_LAZY 499 # - It must meet the requirements for MMU_LAZY_TLB_REFCOUNT=n (see above).
507 config MMU_LAZY_TLB_SHOOTDOWN 500 config MMU_LAZY_TLB_SHOOTDOWN
508 bool 501 bool
509 502
510 config ARCH_HAVE_NMI_SAFE_CMPXCHG 503 config ARCH_HAVE_NMI_SAFE_CMPXCHG
511 bool 504 bool
512 505
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 506 config ARCH_HAS_NMI_SAFE_THIS_CPU_OPS
523 bool 507 bool
524 508
525 config HAVE_ALIGNED_STRUCT_PAGE 509 config HAVE_ALIGNED_STRUCT_PAGE
526 bool 510 bool
527 help 511 help
528 This makes sure that struct pages ar 512 This makes sure that struct pages are double word aligned and that
529 e.g. the SLUB allocator can perform 513 e.g. the SLUB allocator can perform double word atomic operations
530 on a struct page for better performa 514 on a struct page for better performance. However selecting this
531 might increase the size of a struct 515 might increase the size of a struct page by a word.
532 516
533 config HAVE_CMPXCHG_LOCAL 517 config HAVE_CMPXCHG_LOCAL
534 bool 518 bool
535 519
536 config HAVE_CMPXCHG_DOUBLE 520 config HAVE_CMPXCHG_DOUBLE
537 bool 521 bool
538 522
539 config ARCH_WEAK_RELEASE_ACQUIRE 523 config ARCH_WEAK_RELEASE_ACQUIRE
540 bool 524 bool
541 525
542 config ARCH_WANT_IPC_PARSE_VERSION 526 config ARCH_WANT_IPC_PARSE_VERSION
543 bool 527 bool
544 528
545 config ARCH_WANT_COMPAT_IPC_PARSE_VERSION 529 config ARCH_WANT_COMPAT_IPC_PARSE_VERSION
546 bool 530 bool
547 531
548 config ARCH_WANT_OLD_COMPAT_IPC 532 config ARCH_WANT_OLD_COMPAT_IPC
549 select ARCH_WANT_COMPAT_IPC_PARSE_VERS 533 select ARCH_WANT_COMPAT_IPC_PARSE_VERSION
550 bool 534 bool
551 535
552 config HAVE_ARCH_SECCOMP 536 config HAVE_ARCH_SECCOMP
553 bool 537 bool
554 help 538 help
555 An arch should select this symbol to 539 An arch should select this symbol to support seccomp mode 1 (the fixed
556 syscall policy), and must provide an 540 syscall policy), and must provide an overrides for __NR_seccomp_sigreturn,
557 and compat syscalls if the asm-gener 541 and compat syscalls if the asm-generic/seccomp.h defaults need adjustment:
558 - __NR_seccomp_read_32 542 - __NR_seccomp_read_32
559 - __NR_seccomp_write_32 543 - __NR_seccomp_write_32
560 - __NR_seccomp_exit_32 544 - __NR_seccomp_exit_32
561 - __NR_seccomp_sigreturn_32 545 - __NR_seccomp_sigreturn_32
562 546
563 config HAVE_ARCH_SECCOMP_FILTER 547 config HAVE_ARCH_SECCOMP_FILTER
564 bool 548 bool
565 select HAVE_ARCH_SECCOMP 549 select HAVE_ARCH_SECCOMP
566 help 550 help
567 An arch should select this symbol if 551 An arch should select this symbol if it provides all of these things:
568 - all the requirements for HAVE_ARCH 552 - all the requirements for HAVE_ARCH_SECCOMP
569 - syscall_get_arch() 553 - syscall_get_arch()
570 - syscall_get_arguments() 554 - syscall_get_arguments()
571 - syscall_rollback() 555 - syscall_rollback()
572 - syscall_set_return_value() 556 - syscall_set_return_value()
573 - SIGSYS siginfo_t support 557 - SIGSYS siginfo_t support
574 - secure_computing is called from a 558 - secure_computing is called from a ptrace_event()-safe context
575 - secure_computing return value is c 559 - secure_computing return value is checked and a return value of -1
576 results in the system call being s 560 results in the system call being skipped immediately.
577 - seccomp syscall wired up 561 - seccomp syscall wired up
578 - if !HAVE_SPARSE_SYSCALL_NR, have S 562 - if !HAVE_SPARSE_SYSCALL_NR, have SECCOMP_ARCH_NATIVE,
579 SECCOMP_ARCH_NATIVE_NR, SECCOMP_AR 563 SECCOMP_ARCH_NATIVE_NR, SECCOMP_ARCH_NATIVE_NAME defined. If
580 COMPAT is supported, have the SECC 564 COMPAT is supported, have the SECCOMP_ARCH_COMPAT* defines too.
581 565
582 config SECCOMP 566 config SECCOMP
583 prompt "Enable seccomp to safely execu 567 prompt "Enable seccomp to safely execute untrusted bytecode"
584 def_bool y 568 def_bool y
585 depends on HAVE_ARCH_SECCOMP 569 depends on HAVE_ARCH_SECCOMP
586 help 570 help
587 This kernel feature is useful for nu 571 This kernel feature is useful for number crunching applications
588 that may need to handle untrusted by 572 that may need to handle untrusted bytecode during their
589 execution. By using pipes or other t 573 execution. By using pipes or other transports made available
590 to the process as file descriptors s 574 to the process as file descriptors supporting the read/write
591 syscalls, it's possible to isolate t 575 syscalls, it's possible to isolate those applications in their
592 own address space using seccomp. Onc 576 own address space using seccomp. Once seccomp is enabled via
593 prctl(PR_SET_SECCOMP) or the seccomp 577 prctl(PR_SET_SECCOMP) or the seccomp() syscall, it cannot be
594 disabled and the task is only allowe 578 disabled and the task is only allowed to execute a few safe
595 syscalls defined by each seccomp mod 579 syscalls defined by each seccomp mode.
596 580
597 If unsure, say Y. 581 If unsure, say Y.
598 582
599 config SECCOMP_FILTER 583 config SECCOMP_FILTER
600 def_bool y 584 def_bool y
601 depends on HAVE_ARCH_SECCOMP_FILTER && 585 depends on HAVE_ARCH_SECCOMP_FILTER && SECCOMP && NET
602 help 586 help
603 Enable tasks to build secure computi 587 Enable tasks to build secure computing environments defined
604 in terms of Berkeley Packet Filter p 588 in terms of Berkeley Packet Filter programs which implement
605 task-defined system call filtering p 589 task-defined system call filtering polices.
606 590
607 See Documentation/userspace-api/secc 591 See Documentation/userspace-api/seccomp_filter.rst for details.
608 592
609 config SECCOMP_CACHE_DEBUG 593 config SECCOMP_CACHE_DEBUG
610 bool "Show seccomp filter cache status 594 bool "Show seccomp filter cache status in /proc/pid/seccomp_cache"
611 depends on SECCOMP_FILTER && !HAVE_SPA 595 depends on SECCOMP_FILTER && !HAVE_SPARSE_SYSCALL_NR
612 depends on PROC_FS 596 depends on PROC_FS
613 help 597 help
614 This enables the /proc/pid/seccomp_c 598 This enables the /proc/pid/seccomp_cache interface to monitor
615 seccomp cache data. The file format 599 seccomp cache data. The file format is subject to change. Reading
616 the file requires CAP_SYS_ADMIN. 600 the file requires CAP_SYS_ADMIN.
617 601
618 This option is for debugging only. E 602 This option is for debugging only. Enabling presents the risk that
619 an adversary may be able to infer th 603 an adversary may be able to infer the seccomp filter logic.
620 604
621 If unsure, say N. 605 If unsure, say N.
622 606
623 config HAVE_ARCH_STACKLEAK 607 config HAVE_ARCH_STACKLEAK
624 bool 608 bool
625 help 609 help
626 An architecture should select this i 610 An architecture should select this if it has the code which
627 fills the used part of the kernel st 611 fills the used part of the kernel stack with the STACKLEAK_POISON
628 value before returning from system c 612 value before returning from system calls.
629 613
630 config HAVE_STACKPROTECTOR 614 config HAVE_STACKPROTECTOR
631 bool 615 bool
632 help 616 help
633 An arch should select this symbol if 617 An arch should select this symbol if:
634 - it has implemented a stack canary 618 - it has implemented a stack canary (e.g. __stack_chk_guard)
635 619
636 config STACKPROTECTOR 620 config STACKPROTECTOR
637 bool "Stack Protector buffer overflow 621 bool "Stack Protector buffer overflow detection"
638 depends on HAVE_STACKPROTECTOR 622 depends on HAVE_STACKPROTECTOR
639 depends on $(cc-option,-fstack-protect 623 depends on $(cc-option,-fstack-protector)
640 default y 624 default y
641 help 625 help
642 This option turns on the "stack-prot 626 This option turns on the "stack-protector" GCC feature. This
643 feature puts, at the beginning of fu 627 feature puts, at the beginning of functions, a canary value on
644 the stack just before the return add 628 the stack just before the return address, and validates
645 the value just before actually retur 629 the value just before actually returning. Stack based buffer
646 overflows (that need to overwrite th 630 overflows (that need to overwrite this return address) now also
647 overwrite the canary, which gets det 631 overwrite the canary, which gets detected and the attack is then
648 neutralized via a kernel panic. 632 neutralized via a kernel panic.
649 633
650 Functions will have the stack-protec 634 Functions will have the stack-protector canary logic added if they
651 have an 8-byte or larger character a 635 have an 8-byte or larger character array on the stack.
652 636
653 This feature requires gcc version 4. 637 This feature requires gcc version 4.2 or above, or a distribution
654 gcc with the feature backported ("-f 638 gcc with the feature backported ("-fstack-protector").
655 639
656 On an x86 "defconfig" build, this fe 640 On an x86 "defconfig" build, this feature adds canary checks to
657 about 3% of all kernel functions, wh 641 about 3% of all kernel functions, which increases kernel code size
658 by about 0.3%. 642 by about 0.3%.
659 643
660 config STACKPROTECTOR_STRONG 644 config STACKPROTECTOR_STRONG
661 bool "Strong Stack Protector" 645 bool "Strong Stack Protector"
662 depends on STACKPROTECTOR 646 depends on STACKPROTECTOR
663 depends on $(cc-option,-fstack-protect 647 depends on $(cc-option,-fstack-protector-strong)
664 default y 648 default y
665 help 649 help
666 Functions will have the stack-protec 650 Functions will have the stack-protector canary logic added in any
667 of the following conditions: 651 of the following conditions:
668 652
669 - local variable's address used as p 653 - local variable's address used as part of the right hand side of an
670 assignment or function argument 654 assignment or function argument
671 - local variable is an array (or uni 655 - local variable is an array (or union containing an array),
672 regardless of array type or length 656 regardless of array type or length
673 - uses register local variables 657 - uses register local variables
674 658
675 This feature requires gcc version 4. 659 This feature requires gcc version 4.9 or above, or a distribution
676 gcc with the feature backported ("-f 660 gcc with the feature backported ("-fstack-protector-strong").
677 661
678 On an x86 "defconfig" build, this fe 662 On an x86 "defconfig" build, this feature adds canary checks to
679 about 20% of all kernel functions, w 663 about 20% of all kernel functions, which increases the kernel code
680 size by about 2%. 664 size by about 2%.
681 665
682 config ARCH_SUPPORTS_SHADOW_CALL_STACK 666 config ARCH_SUPPORTS_SHADOW_CALL_STACK
683 bool 667 bool
684 help 668 help
685 An architecture should select this i 669 An architecture should select this if it supports the compiler's
686 Shadow Call Stack and implements run 670 Shadow Call Stack and implements runtime support for shadow stack
687 switching. 671 switching.
688 672
689 config SHADOW_CALL_STACK 673 config SHADOW_CALL_STACK
690 bool "Shadow Call Stack" 674 bool "Shadow Call Stack"
691 depends on ARCH_SUPPORTS_SHADOW_CALL_S 675 depends on ARCH_SUPPORTS_SHADOW_CALL_STACK
692 depends on DYNAMIC_FTRACE_WITH_ARGS || 676 depends on DYNAMIC_FTRACE_WITH_ARGS || DYNAMIC_FTRACE_WITH_REGS || !FUNCTION_GRAPH_TRACER
693 depends on MMU <<
694 help 677 help
695 This option enables the compiler's S 678 This option enables the compiler's Shadow Call Stack, which
696 uses a shadow stack to protect funct 679 uses a shadow stack to protect function return addresses from
697 being overwritten by an attacker. Mo 680 being overwritten by an attacker. More information can be found
698 in the compiler's documentation: 681 in the compiler's documentation:
699 682
700 - Clang: https://clang.llvm.org/docs 683 - Clang: https://clang.llvm.org/docs/ShadowCallStack.html
701 - GCC: https://gcc.gnu.org/onlinedoc 684 - GCC: https://gcc.gnu.org/onlinedocs/gcc/Instrumentation-Options.html#Instrumentation-Options
702 685
703 Note that security guarantees in the 686 Note that security guarantees in the kernel differ from the
704 ones documented for user space. The 687 ones documented for user space. The kernel must store addresses
705 of shadow stacks in memory, which me 688 of shadow stacks in memory, which means an attacker capable of
706 reading and writing arbitrary memory 689 reading and writing arbitrary memory may be able to locate them
707 and hijack control flow by modifying 690 and hijack control flow by modifying the stacks.
708 691
709 config DYNAMIC_SCS 692 config DYNAMIC_SCS
710 bool 693 bool
711 help 694 help
712 Set by the arch code if it relies on 695 Set by the arch code if it relies on code patching to insert the
713 shadow call stack push and pop instr 696 shadow call stack push and pop instructions rather than on the
714 compiler. 697 compiler.
715 698
716 config LTO 699 config LTO
717 bool 700 bool
718 help 701 help
719 Selected if the kernel will be built 702 Selected if the kernel will be built using the compiler's LTO feature.
720 703
721 config LTO_CLANG 704 config LTO_CLANG
722 bool 705 bool
723 select LTO 706 select LTO
724 help 707 help
725 Selected if the kernel will be built 708 Selected if the kernel will be built using Clang's LTO feature.
726 709
727 config ARCH_SUPPORTS_LTO_CLANG 710 config ARCH_SUPPORTS_LTO_CLANG
728 bool 711 bool
729 help 712 help
730 An architecture should select this o 713 An architecture should select this option if it supports:
731 - compiling with Clang, 714 - compiling with Clang,
732 - compiling inline assembly with Cla 715 - compiling inline assembly with Clang's integrated assembler,
733 - and linking with LLD. 716 - and linking with LLD.
734 717
735 config ARCH_SUPPORTS_LTO_CLANG_THIN 718 config ARCH_SUPPORTS_LTO_CLANG_THIN
736 bool 719 bool
737 help 720 help
738 An architecture should select this o 721 An architecture should select this option if it can support Clang's
739 ThinLTO mode. 722 ThinLTO mode.
740 723
741 config HAS_LTO_CLANG 724 config HAS_LTO_CLANG
742 def_bool y 725 def_bool y
743 depends on CC_IS_CLANG && LD_IS_LLD && 726 depends on CC_IS_CLANG && LD_IS_LLD && AS_IS_LLVM
744 depends on $(success,$(NM) --help | he 727 depends on $(success,$(NM) --help | head -n 1 | grep -qi llvm)
745 depends on $(success,$(AR) --help | he 728 depends on $(success,$(AR) --help | head -n 1 | grep -qi llvm)
746 depends on ARCH_SUPPORTS_LTO_CLANG 729 depends on ARCH_SUPPORTS_LTO_CLANG
747 depends on !FTRACE_MCOUNT_USE_RECORDMC 730 depends on !FTRACE_MCOUNT_USE_RECORDMCOUNT
748 # https://github.com/ClangBuiltLinux/l !! 731 depends on !KASAN || KASAN_HW_TAGS
749 depends on (!KASAN || KASAN_HW_TAGS || <<
750 depends on (!KCOV || CLANG_VERSION >= <<
751 depends on !GCOV_KERNEL 732 depends on !GCOV_KERNEL
752 help 733 help
753 The compiler and Kconfig options sup 734 The compiler and Kconfig options support building with Clang's
754 LTO. 735 LTO.
755 736
756 choice 737 choice
757 prompt "Link Time Optimization (LTO)" 738 prompt "Link Time Optimization (LTO)"
758 default LTO_NONE 739 default LTO_NONE
759 help 740 help
760 This option enables Link Time Optimi 741 This option enables Link Time Optimization (LTO), which allows the
761 compiler to optimize binaries global 742 compiler to optimize binaries globally.
762 743
763 If unsure, select LTO_NONE. Note tha 744 If unsure, select LTO_NONE. Note that LTO is very resource-intensive
764 so it's disabled by default. 745 so it's disabled by default.
765 746
766 config LTO_NONE 747 config LTO_NONE
767 bool "None" 748 bool "None"
768 help 749 help
769 Build the kernel normally, without L 750 Build the kernel normally, without Link Time Optimization (LTO).
770 751
771 config LTO_CLANG_FULL 752 config LTO_CLANG_FULL
772 bool "Clang Full LTO (EXPERIMENTAL)" 753 bool "Clang Full LTO (EXPERIMENTAL)"
773 depends on HAS_LTO_CLANG 754 depends on HAS_LTO_CLANG
774 depends on !COMPILE_TEST 755 depends on !COMPILE_TEST
775 select LTO_CLANG 756 select LTO_CLANG
776 help 757 help
777 This option enables Clang's full Lin 758 This option enables Clang's full Link Time Optimization (LTO), which
778 allows the compiler to optimize the 759 allows the compiler to optimize the kernel globally. If you enable
779 this option, the compiler generates 760 this option, the compiler generates LLVM bitcode instead of ELF
780 object files, and the actual compila 761 object files, and the actual compilation from bitcode happens at
781 the LTO link step, which may take se 762 the LTO link step, which may take several minutes depending on the
782 kernel configuration. More informati 763 kernel configuration. More information can be found from LLVM's
783 documentation: 764 documentation:
784 765
785 https://llvm.org/docs/LinkTimeOpti 766 https://llvm.org/docs/LinkTimeOptimization.html
786 767
787 During link time, this option can us 768 During link time, this option can use a large amount of RAM, and
788 may take much longer than the ThinLT 769 may take much longer than the ThinLTO option.
789 770
790 config LTO_CLANG_THIN 771 config LTO_CLANG_THIN
791 bool "Clang ThinLTO (EXPERIMENTAL)" 772 bool "Clang ThinLTO (EXPERIMENTAL)"
792 depends on HAS_LTO_CLANG && ARCH_SUPPO 773 depends on HAS_LTO_CLANG && ARCH_SUPPORTS_LTO_CLANG_THIN
793 select LTO_CLANG 774 select LTO_CLANG
794 help 775 help
795 This option enables Clang's ThinLTO, 776 This option enables Clang's ThinLTO, which allows for parallel
796 optimization and faster incremental 777 optimization and faster incremental compiles compared to the
797 CONFIG_LTO_CLANG_FULL option. More i 778 CONFIG_LTO_CLANG_FULL option. More information can be found
798 from Clang's documentation: 779 from Clang's documentation:
799 780
800 https://clang.llvm.org/docs/ThinLT 781 https://clang.llvm.org/docs/ThinLTO.html
801 782
802 If unsure, say Y. 783 If unsure, say Y.
803 endchoice 784 endchoice
804 785
805 config ARCH_SUPPORTS_CFI_CLANG 786 config ARCH_SUPPORTS_CFI_CLANG
806 bool 787 bool
807 help 788 help
808 An architecture should select this o 789 An architecture should select this option if it can support Clang's
809 Control-Flow Integrity (CFI) checkin 790 Control-Flow Integrity (CFI) checking.
810 791
811 config ARCH_USES_CFI_TRAPS 792 config ARCH_USES_CFI_TRAPS
812 bool 793 bool
813 794
814 config CFI_CLANG 795 config CFI_CLANG
815 bool "Use Clang's Control Flow Integri 796 bool "Use Clang's Control Flow Integrity (CFI)"
816 depends on ARCH_SUPPORTS_CFI_CLANG 797 depends on ARCH_SUPPORTS_CFI_CLANG
817 depends on $(cc-option,-fsanitize=kcfi 798 depends on $(cc-option,-fsanitize=kcfi)
818 help 799 help
819 This option enables Clang's forward- !! 800 This option enables Clang’s forward-edge Control Flow Integrity
820 (CFI) checking, where the compiler i 801 (CFI) checking, where the compiler injects a runtime check to each
821 indirect function call to ensure the 802 indirect function call to ensure the target is a valid function with
822 the correct static type. This restri 803 the correct static type. This restricts possible call targets and
823 makes it more difficult for an attac 804 makes it more difficult for an attacker to exploit bugs that allow
824 the modification of stored function 805 the modification of stored function pointers. More information can be
825 found from Clang's documentation: 806 found from Clang's documentation:
826 807
827 https://clang.llvm.org/docs/Contro 808 https://clang.llvm.org/docs/ControlFlowIntegrity.html
828 809
829 config CFI_PERMISSIVE 810 config CFI_PERMISSIVE
830 bool "Use CFI in permissive mode" 811 bool "Use CFI in permissive mode"
831 depends on CFI_CLANG 812 depends on CFI_CLANG
832 help 813 help
833 When selected, Control Flow Integrit 814 When selected, Control Flow Integrity (CFI) violations result in a
834 warning instead of a kernel panic. T 815 warning instead of a kernel panic. This option should only be used
835 for finding indirect call type misma 816 for finding indirect call type mismatches during development.
836 817
837 If unsure, say N. 818 If unsure, say N.
838 819
839 config HAVE_ARCH_WITHIN_STACK_FRAMES 820 config HAVE_ARCH_WITHIN_STACK_FRAMES
840 bool 821 bool
841 help 822 help
842 An architecture should select this i 823 An architecture should select this if it can walk the kernel stack
843 frames to determine if an object is 824 frames to determine if an object is part of either the arguments
844 or local variables (i.e. that it exc 825 or local variables (i.e. that it excludes saved return addresses,
845 and similar) by implementing an inli 826 and similar) by implementing an inline arch_within_stack_frames(),
846 which is used by CONFIG_HARDENED_USE 827 which is used by CONFIG_HARDENED_USERCOPY.
847 828
848 config HAVE_CONTEXT_TRACKING_USER 829 config HAVE_CONTEXT_TRACKING_USER
849 bool 830 bool
850 help 831 help
851 Provide kernel/user boundaries probe 832 Provide kernel/user boundaries probes necessary for subsystems
852 that need it, such as userspace RCU 833 that need it, such as userspace RCU extended quiescent state.
853 Syscalls need to be wrapped inside u 834 Syscalls need to be wrapped inside user_exit()-user_enter(), either
854 optimized behind static key or throu 835 optimized behind static key or through the slow path using TIF_NOHZ
855 flag. Exceptions handlers must be wr 836 flag. Exceptions handlers must be wrapped as well. Irqs are already
856 protected inside ct_irq_enter/ct_irq 837 protected inside ct_irq_enter/ct_irq_exit() but preemption or signal
857 handling on irq exit still need to b 838 handling on irq exit still need to be protected.
858 839
859 config HAVE_CONTEXT_TRACKING_USER_OFFSTACK 840 config HAVE_CONTEXT_TRACKING_USER_OFFSTACK
860 bool 841 bool
861 help 842 help
862 Architecture neither relies on excep 843 Architecture neither relies on exception_enter()/exception_exit()
863 nor on schedule_user(). Also preempt 844 nor on schedule_user(). Also preempt_schedule_notrace() and
864 preempt_schedule_irq() can't be call 845 preempt_schedule_irq() can't be called in a preemptible section
865 while context tracking is CONTEXT_US 846 while context tracking is CONTEXT_USER. This feature reflects a sane
866 entry implementation where the follo 847 entry implementation where the following requirements are met on
867 critical entry code, ie: before user 848 critical entry code, ie: before user_exit() or after user_enter():
868 849
869 - Critical entry code isn't preempti 850 - Critical entry code isn't preemptible (or better yet:
870 not interruptible). 851 not interruptible).
871 - No use of RCU read side critical s 852 - No use of RCU read side critical sections, unless ct_nmi_enter()
872 got called. 853 got called.
873 - No use of instrumentation, unless 854 - No use of instrumentation, unless instrumentation_begin() got
874 called. 855 called.
875 856
876 config HAVE_TIF_NOHZ 857 config HAVE_TIF_NOHZ
877 bool 858 bool
878 help 859 help
879 Arch relies on TIF_NOHZ and syscall 860 Arch relies on TIF_NOHZ and syscall slow path to implement context
880 tracking calls to user_enter()/user_ 861 tracking calls to user_enter()/user_exit().
881 862
882 config HAVE_VIRT_CPU_ACCOUNTING 863 config HAVE_VIRT_CPU_ACCOUNTING
883 bool 864 bool
884 865
885 config HAVE_VIRT_CPU_ACCOUNTING_IDLE 866 config HAVE_VIRT_CPU_ACCOUNTING_IDLE
886 bool 867 bool
887 help 868 help
888 Architecture has its own way to acco 869 Architecture has its own way to account idle CPU time and therefore
889 doesn't implement vtime_account_idle 870 doesn't implement vtime_account_idle().
890 871
891 config ARCH_HAS_SCALED_CPUTIME 872 config ARCH_HAS_SCALED_CPUTIME
892 bool 873 bool
893 874
894 config HAVE_VIRT_CPU_ACCOUNTING_GEN 875 config HAVE_VIRT_CPU_ACCOUNTING_GEN
895 bool 876 bool
896 default y if 64BIT 877 default y if 64BIT
897 help 878 help
898 With VIRT_CPU_ACCOUNTING_GEN, cputim 879 With VIRT_CPU_ACCOUNTING_GEN, cputime_t becomes 64-bit.
899 Before enabling this option, arch co 880 Before enabling this option, arch code must be audited
900 to ensure there are no races in conc 881 to ensure there are no races in concurrent read/write of
901 cputime_t. For example, reading/writ 882 cputime_t. For example, reading/writing 64-bit cputime_t on
902 some 32-bit arches may require multi 883 some 32-bit arches may require multiple accesses, so proper
903 locking is needed to protect against 884 locking is needed to protect against concurrent accesses.
904 885
905 config HAVE_IRQ_TIME_ACCOUNTING 886 config HAVE_IRQ_TIME_ACCOUNTING
906 bool 887 bool
907 help 888 help
908 Archs need to ensure they use a high 889 Archs need to ensure they use a high enough resolution clock to
909 support irq time accounting and then 890 support irq time accounting and then call enable_sched_clock_irqtime().
910 891
911 config HAVE_MOVE_PUD 892 config HAVE_MOVE_PUD
912 bool 893 bool
913 help 894 help
914 Architectures that select this are a 895 Architectures that select this are able to move page tables at the
915 PUD level. If there are only 3 page 896 PUD level. If there are only 3 page table levels, the move effectively
916 happens at the PGD level. 897 happens at the PGD level.
917 898
918 config HAVE_MOVE_PMD 899 config HAVE_MOVE_PMD
919 bool 900 bool
920 help 901 help
921 Archs that select this are able to m 902 Archs that select this are able to move page tables at the PMD level.
922 903
923 config HAVE_ARCH_TRANSPARENT_HUGEPAGE 904 config HAVE_ARCH_TRANSPARENT_HUGEPAGE
924 bool 905 bool
925 906
926 config HAVE_ARCH_TRANSPARENT_HUGEPAGE_PUD 907 config HAVE_ARCH_TRANSPARENT_HUGEPAGE_PUD
927 bool 908 bool
928 909
929 config HAVE_ARCH_HUGE_VMAP 910 config HAVE_ARCH_HUGE_VMAP
930 bool 911 bool
931 912
932 # 913 #
933 # Archs that select this would be capable of 914 # Archs that select this would be capable of PMD-sized vmaps (i.e.,
934 # arch_vmap_pmd_supported() returns true). Th 915 # arch_vmap_pmd_supported() returns true). The VM_ALLOW_HUGE_VMAP flag
935 # must be used to enable allocations to use h 916 # must be used to enable allocations to use hugepages.
936 # 917 #
937 config HAVE_ARCH_HUGE_VMALLOC 918 config HAVE_ARCH_HUGE_VMALLOC
938 depends on HAVE_ARCH_HUGE_VMAP 919 depends on HAVE_ARCH_HUGE_VMAP
939 bool 920 bool
940 921
941 config ARCH_WANT_HUGE_PMD_SHARE 922 config ARCH_WANT_HUGE_PMD_SHARE
942 bool 923 bool
943 924
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 925 config HAVE_ARCH_SOFT_DIRTY
953 bool 926 bool
954 927
955 config HAVE_MOD_ARCH_SPECIFIC 928 config HAVE_MOD_ARCH_SPECIFIC
956 bool 929 bool
957 help 930 help
958 The arch uses struct mod_arch_specif 931 The arch uses struct mod_arch_specific to store data. Many arches
959 just need a simple module loader wit 932 just need a simple module loader without arch specific data - those
960 should not enable this. 933 should not enable this.
961 934
962 config MODULES_USE_ELF_RELA 935 config MODULES_USE_ELF_RELA
963 bool 936 bool
964 help 937 help
965 Modules only use ELF RELA relocation 938 Modules only use ELF RELA relocations. Modules with ELF REL
966 relocations will give an error. 939 relocations will give an error.
967 940
968 config MODULES_USE_ELF_REL 941 config MODULES_USE_ELF_REL
969 bool 942 bool
970 help 943 help
971 Modules only use ELF REL relocations 944 Modules only use ELF REL relocations. Modules with ELF RELA
972 relocations will give an error. 945 relocations will give an error.
973 946
974 config ARCH_WANTS_MODULES_DATA_IN_VMALLOC 947 config ARCH_WANTS_MODULES_DATA_IN_VMALLOC
975 bool 948 bool
976 help 949 help
977 For architectures like powerpc/32 wh 950 For architectures like powerpc/32 which have constraints on module
978 allocation and need to allocate modu 951 allocation and need to allocate module data outside of module area.
979 952
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 953 config HAVE_IRQ_EXIT_ON_IRQ_STACK
989 bool 954 bool
990 help 955 help
991 Architecture doesn't only execute th 956 Architecture doesn't only execute the irq handler on the irq stack
992 but also irq_exit(). This way we can 957 but also irq_exit(). This way we can process softirqs on this irq
993 stack instead of switching to a new 958 stack instead of switching to a new one when we call __do_softirq()
994 in the end of an hardirq. 959 in the end of an hardirq.
995 This spares a stack switch and impro 960 This spares a stack switch and improves cache usage on softirq
996 processing. 961 processing.
997 962
998 config HAVE_SOFTIRQ_ON_OWN_STACK 963 config HAVE_SOFTIRQ_ON_OWN_STACK
999 bool 964 bool
1000 help 965 help
1001 Architecture provides a function to 966 Architecture provides a function to run __do_softirq() on a
1002 separate stack. 967 separate stack.
1003 968
1004 config SOFTIRQ_ON_OWN_STACK 969 config SOFTIRQ_ON_OWN_STACK
1005 def_bool HAVE_SOFTIRQ_ON_OWN_STACK && 970 def_bool HAVE_SOFTIRQ_ON_OWN_STACK && !PREEMPT_RT
1006 971
1007 config ALTERNATE_USER_ADDRESS_SPACE 972 config ALTERNATE_USER_ADDRESS_SPACE
1008 bool 973 bool
1009 help 974 help
1010 Architectures set this when the CPU 975 Architectures set this when the CPU uses separate address
1011 spaces for kernel and user space po 976 spaces for kernel and user space pointers. In this case, the
1012 access_ok() check on a __user point 977 access_ok() check on a __user pointer is skipped.
1013 978
1014 config PGTABLE_LEVELS 979 config PGTABLE_LEVELS
1015 int 980 int
1016 default 2 981 default 2
1017 982
1018 config ARCH_HAS_ELF_RANDOMIZE 983 config ARCH_HAS_ELF_RANDOMIZE
1019 bool 984 bool
1020 help 985 help
1021 An architecture supports choosing r 986 An architecture supports choosing randomized locations for
1022 stack, mmap, brk, and ET_DYN. Defin 987 stack, mmap, brk, and ET_DYN. Defined functions:
1023 - arch_mmap_rnd() 988 - arch_mmap_rnd()
1024 - arch_randomize_brk() 989 - arch_randomize_brk()
1025 990
1026 config HAVE_ARCH_MMAP_RND_BITS 991 config HAVE_ARCH_MMAP_RND_BITS
1027 bool 992 bool
1028 help 993 help
1029 An arch should select this symbol i 994 An arch should select this symbol if it supports setting a variable
1030 number of bits for use in establish 995 number of bits for use in establishing the base address for mmap
1031 allocations, has MMU enabled and pr 996 allocations, has MMU enabled and provides values for both:
1032 - ARCH_MMAP_RND_BITS_MIN 997 - ARCH_MMAP_RND_BITS_MIN
1033 - ARCH_MMAP_RND_BITS_MAX 998 - ARCH_MMAP_RND_BITS_MAX
1034 999
1035 config HAVE_EXIT_THREAD 1000 config HAVE_EXIT_THREAD
1036 bool 1001 bool
1037 help 1002 help
1038 An architecture implements exit_thr 1003 An architecture implements exit_thread.
1039 1004
1040 config ARCH_MMAP_RND_BITS_MIN 1005 config ARCH_MMAP_RND_BITS_MIN
1041 int 1006 int
1042 1007
1043 config ARCH_MMAP_RND_BITS_MAX 1008 config ARCH_MMAP_RND_BITS_MAX
1044 int 1009 int
1045 1010
1046 config ARCH_MMAP_RND_BITS_DEFAULT 1011 config ARCH_MMAP_RND_BITS_DEFAULT
1047 int 1012 int
1048 1013
1049 config ARCH_MMAP_RND_BITS 1014 config ARCH_MMAP_RND_BITS
1050 int "Number of bits to use for ASLR o 1015 int "Number of bits to use for ASLR of mmap base address" if EXPERT
1051 range ARCH_MMAP_RND_BITS_MIN ARCH_MMA 1016 range ARCH_MMAP_RND_BITS_MIN ARCH_MMAP_RND_BITS_MAX
1052 default ARCH_MMAP_RND_BITS_DEFAULT if 1017 default ARCH_MMAP_RND_BITS_DEFAULT if ARCH_MMAP_RND_BITS_DEFAULT
1053 default ARCH_MMAP_RND_BITS_MIN 1018 default ARCH_MMAP_RND_BITS_MIN
1054 depends on HAVE_ARCH_MMAP_RND_BITS 1019 depends on HAVE_ARCH_MMAP_RND_BITS
1055 help 1020 help
1056 This value can be used to select th 1021 This value can be used to select the number of bits to use to
1057 determine the random offset to the 1022 determine the random offset to the base address of vma regions
1058 resulting from mmap allocations. Th 1023 resulting from mmap allocations. This value will be bounded
1059 by the architecture's minimum and m 1024 by the architecture's minimum and maximum supported values.
1060 1025
1061 This value can be changed after boo 1026 This value can be changed after boot using the
1062 /proc/sys/vm/mmap_rnd_bits tunable 1027 /proc/sys/vm/mmap_rnd_bits tunable
1063 1028
1064 config HAVE_ARCH_MMAP_RND_COMPAT_BITS 1029 config HAVE_ARCH_MMAP_RND_COMPAT_BITS
1065 bool 1030 bool
1066 help 1031 help
1067 An arch should select this symbol i 1032 An arch should select this symbol if it supports running applications
1068 in compatibility mode, supports set 1033 in compatibility mode, supports setting a variable number of bits for
1069 use in establishing the base addres 1034 use in establishing the base address for mmap allocations, has MMU
1070 enabled and provides values for bot 1035 enabled and provides values for both:
1071 - ARCH_MMAP_RND_COMPAT_BITS_MIN 1036 - ARCH_MMAP_RND_COMPAT_BITS_MIN
1072 - ARCH_MMAP_RND_COMPAT_BITS_MAX 1037 - ARCH_MMAP_RND_COMPAT_BITS_MAX
1073 1038
1074 config ARCH_MMAP_RND_COMPAT_BITS_MIN 1039 config ARCH_MMAP_RND_COMPAT_BITS_MIN
1075 int 1040 int
1076 1041
1077 config ARCH_MMAP_RND_COMPAT_BITS_MAX 1042 config ARCH_MMAP_RND_COMPAT_BITS_MAX
1078 int 1043 int
1079 1044
1080 config ARCH_MMAP_RND_COMPAT_BITS_DEFAULT 1045 config ARCH_MMAP_RND_COMPAT_BITS_DEFAULT
1081 int 1046 int
1082 1047
1083 config ARCH_MMAP_RND_COMPAT_BITS 1048 config ARCH_MMAP_RND_COMPAT_BITS
1084 int "Number of bits to use for ASLR o 1049 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 1050 range ARCH_MMAP_RND_COMPAT_BITS_MIN ARCH_MMAP_RND_COMPAT_BITS_MAX
1086 default ARCH_MMAP_RND_COMPAT_BITS_DEF 1051 default ARCH_MMAP_RND_COMPAT_BITS_DEFAULT if ARCH_MMAP_RND_COMPAT_BITS_DEFAULT
1087 default ARCH_MMAP_RND_COMPAT_BITS_MIN 1052 default ARCH_MMAP_RND_COMPAT_BITS_MIN
1088 depends on HAVE_ARCH_MMAP_RND_COMPAT_ 1053 depends on HAVE_ARCH_MMAP_RND_COMPAT_BITS
1089 help 1054 help
1090 This value can be used to select th 1055 This value can be used to select the number of bits to use to
1091 determine the random offset to the 1056 determine the random offset to the base address of vma regions
1092 resulting from mmap allocations for 1057 resulting from mmap allocations for compatible applications This
1093 value will be bounded by the archit 1058 value will be bounded by the architecture's minimum and maximum
1094 supported values. 1059 supported values.
1095 1060
1096 This value can be changed after boo 1061 This value can be changed after boot using the
1097 /proc/sys/vm/mmap_rnd_compat_bits t 1062 /proc/sys/vm/mmap_rnd_compat_bits tunable
1098 1063
1099 config HAVE_ARCH_COMPAT_MMAP_BASES 1064 config HAVE_ARCH_COMPAT_MMAP_BASES
1100 bool 1065 bool
1101 help 1066 help
1102 This allows 64bit applications to i 1067 This allows 64bit applications to invoke 32-bit mmap() syscall
1103 and vice-versa 32-bit applications 1068 and vice-versa 32-bit applications to call 64-bit mmap().
1104 Required for applications doing dif 1069 Required for applications doing different bitness syscalls.
1105 1070
1106 config HAVE_PAGE_SIZE_4KB <<
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 <<
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 <<
1182 256KiB pages have little practical <<
1183 memory usage. The kernel will only <<
1184 that have been compiled with '-zmax <<
1185 (the default is 64KiB or 4KiB on mo <<
1186 <<
1187 endchoice <<
1188 <<
1189 config PAGE_SIZE_LESS_THAN_64KB 1071 config PAGE_SIZE_LESS_THAN_64KB
1190 def_bool y 1072 def_bool y
>> 1073 depends on !ARM64_64K_PAGES
>> 1074 depends on !IA64_PAGE_SIZE_64KB
1191 depends on !PAGE_SIZE_64KB 1075 depends on !PAGE_SIZE_64KB
>> 1076 depends on !PARISC_PAGE_SIZE_64KB
1192 depends on PAGE_SIZE_LESS_THAN_256KB 1077 depends on PAGE_SIZE_LESS_THAN_256KB
1193 1078
1194 config PAGE_SIZE_LESS_THAN_256KB 1079 config PAGE_SIZE_LESS_THAN_256KB
1195 def_bool y 1080 def_bool y
1196 depends on !PAGE_SIZE_256KB 1081 depends on !PAGE_SIZE_256KB
1197 1082
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 1083 # This allows to use a set of generic functions to determine mmap base
1208 # address by giving priority to top-down sche 1084 # address by giving priority to top-down scheme only if the process
1209 # is not in legacy mode (compat task, unlimit 1085 # is not in legacy mode (compat task, unlimited stack size or
1210 # sysctl_legacy_va_layout). 1086 # sysctl_legacy_va_layout).
1211 # Architecture that selects this option can p 1087 # Architecture that selects this option can provide its own version of:
1212 # - STACK_RND_MASK 1088 # - STACK_RND_MASK
1213 config ARCH_WANT_DEFAULT_TOPDOWN_MMAP_LAYOUT 1089 config ARCH_WANT_DEFAULT_TOPDOWN_MMAP_LAYOUT
1214 bool 1090 bool
1215 depends on MMU 1091 depends on MMU
1216 select ARCH_HAS_ELF_RANDOMIZE 1092 select ARCH_HAS_ELF_RANDOMIZE
1217 1093
1218 config HAVE_OBJTOOL 1094 config HAVE_OBJTOOL
1219 bool 1095 bool
1220 1096
1221 config HAVE_JUMP_LABEL_HACK 1097 config HAVE_JUMP_LABEL_HACK
1222 bool 1098 bool
1223 1099
1224 config HAVE_NOINSTR_HACK 1100 config HAVE_NOINSTR_HACK
1225 bool 1101 bool
1226 1102
1227 config HAVE_NOINSTR_VALIDATION 1103 config HAVE_NOINSTR_VALIDATION
1228 bool 1104 bool
1229 1105
1230 config HAVE_UACCESS_VALIDATION 1106 config HAVE_UACCESS_VALIDATION
1231 bool 1107 bool
1232 select OBJTOOL 1108 select OBJTOOL
1233 1109
1234 config HAVE_STACK_VALIDATION 1110 config HAVE_STACK_VALIDATION
1235 bool 1111 bool
1236 help 1112 help
1237 Architecture supports objtool compi 1113 Architecture supports objtool compile-time frame pointer rule
1238 validation. 1114 validation.
1239 1115
1240 config HAVE_RELIABLE_STACKTRACE 1116 config HAVE_RELIABLE_STACKTRACE
1241 bool 1117 bool
1242 help 1118 help
1243 Architecture has either save_stack_ 1119 Architecture has either save_stack_trace_tsk_reliable() or
1244 arch_stack_walk_reliable() function 1120 arch_stack_walk_reliable() function which only returns a stack trace
1245 if it can guarantee the trace is re 1121 if it can guarantee the trace is reliable.
1246 1122
1247 config HAVE_ARCH_HASH 1123 config HAVE_ARCH_HASH
1248 bool 1124 bool
1249 default n 1125 default n
1250 help 1126 help
1251 If this is set, the architecture pr 1127 If this is set, the architecture provides an <asm/hash.h>
1252 file which provides platform-specif 1128 file which provides platform-specific implementations of some
1253 functions in <linux/hash.h> or fs/n 1129 functions in <linux/hash.h> or fs/namei.c.
1254 1130
1255 config HAVE_ARCH_NVRAM_OPS 1131 config HAVE_ARCH_NVRAM_OPS
1256 bool 1132 bool
1257 1133
1258 config ISA_BUS_API 1134 config ISA_BUS_API
1259 def_bool ISA 1135 def_bool ISA
1260 1136
1261 # 1137 #
1262 # ABI hall of shame 1138 # ABI hall of shame
1263 # 1139 #
1264 config CLONE_BACKWARDS 1140 config CLONE_BACKWARDS
1265 bool 1141 bool
1266 help 1142 help
1267 Architecture has tls passed as the 1143 Architecture has tls passed as the 4th argument of clone(2),
1268 not the 5th one. 1144 not the 5th one.
1269 1145
1270 config CLONE_BACKWARDS2 1146 config CLONE_BACKWARDS2
1271 bool 1147 bool
1272 help 1148 help
1273 Architecture has the first two argu 1149 Architecture has the first two arguments of clone(2) swapped.
1274 1150
1275 config CLONE_BACKWARDS3 1151 config CLONE_BACKWARDS3
1276 bool 1152 bool
1277 help 1153 help
1278 Architecture has tls passed as the 1154 Architecture has tls passed as the 3rd argument of clone(2),
1279 not the 5th one. 1155 not the 5th one.
1280 1156
1281 config ODD_RT_SIGACTION 1157 config ODD_RT_SIGACTION
1282 bool 1158 bool
1283 help 1159 help
1284 Architecture has unusual rt_sigacti 1160 Architecture has unusual rt_sigaction(2) arguments
1285 1161
1286 config OLD_SIGSUSPEND 1162 config OLD_SIGSUSPEND
1287 bool 1163 bool
1288 help 1164 help
1289 Architecture has old sigsuspend(2) 1165 Architecture has old sigsuspend(2) syscall, of one-argument variety
1290 1166
1291 config OLD_SIGSUSPEND3 1167 config OLD_SIGSUSPEND3
1292 bool 1168 bool
1293 help 1169 help
1294 Even weirder antique ABI - three-ar 1170 Even weirder antique ABI - three-argument sigsuspend(2)
1295 1171
1296 config OLD_SIGACTION 1172 config OLD_SIGACTION
1297 bool 1173 bool
1298 help 1174 help
1299 Architecture has old sigaction(2) s 1175 Architecture has old sigaction(2) syscall. Nope, not the same
1300 as OLD_SIGSUSPEND | OLD_SIGSUSPEND3 1176 as OLD_SIGSUSPEND | OLD_SIGSUSPEND3 - alpha has sigsuspend(2),
1301 but fairly different variant of sig 1177 but fairly different variant of sigaction(2), thanks to OSF/1
1302 compatibility... 1178 compatibility...
1303 1179
1304 config COMPAT_OLD_SIGACTION 1180 config COMPAT_OLD_SIGACTION
1305 bool 1181 bool
1306 1182
1307 config COMPAT_32BIT_TIME 1183 config COMPAT_32BIT_TIME
1308 bool "Provide system calls for 32-bit 1184 bool "Provide system calls for 32-bit time_t"
1309 default !64BIT || COMPAT 1185 default !64BIT || COMPAT
1310 help 1186 help
1311 This enables 32 bit time_t support 1187 This enables 32 bit time_t support in addition to 64 bit time_t support.
1312 This is relevant on all 32-bit arch 1188 This is relevant on all 32-bit architectures, and 64-bit architectures
1313 as part of compat syscall handling. 1189 as part of compat syscall handling.
1314 1190
1315 config ARCH_NO_PREEMPT 1191 config ARCH_NO_PREEMPT
1316 bool 1192 bool
1317 1193
>> 1194 config ARCH_EPHEMERAL_INODES
>> 1195 def_bool n
>> 1196 help
>> 1197 An arch should select this symbol if it doesn't keep track of inode
>> 1198 instances on its own, but instead relies on something else (e.g. the
>> 1199 host kernel for an UML kernel).
>> 1200
1318 config ARCH_SUPPORTS_RT 1201 config ARCH_SUPPORTS_RT
1319 bool 1202 bool
1320 1203
1321 config CPU_NO_EFFICIENT_FFS 1204 config CPU_NO_EFFICIENT_FFS
1322 def_bool n 1205 def_bool n
1323 1206
1324 config HAVE_ARCH_VMAP_STACK 1207 config HAVE_ARCH_VMAP_STACK
1325 def_bool n 1208 def_bool n
1326 help 1209 help
1327 An arch should select this symbol i 1210 An arch should select this symbol if it can support kernel stacks
1328 in vmalloc space. This means: 1211 in vmalloc space. This means:
1329 1212
1330 - vmalloc space must be large enoug 1213 - vmalloc space must be large enough to hold many kernel stacks.
1331 This may rule out many 32-bit arc 1214 This may rule out many 32-bit architectures.
1332 1215
1333 - Stacks in vmalloc space need to w 1216 - Stacks in vmalloc space need to work reliably. For example, if
1334 vmap page tables are created on d 1217 vmap page tables are created on demand, either this mechanism
1335 needs to work while the stack poi 1218 needs to work while the stack points to a virtual address with
1336 unpopulated page tables or arch c 1219 unpopulated page tables or arch code (switch_to() and switch_mm(),
1337 most likely) needs to ensure that 1220 most likely) needs to ensure that the stack's page table entries
1338 are populated before running on a 1221 are populated before running on a possibly unpopulated stack.
1339 1222
1340 - If the stack overflows into a gua 1223 - If the stack overflows into a guard page, something reasonable
1341 should happen. The definition of 1224 should happen. The definition of "reasonable" is flexible, but
1342 instantly rebooting without loggi 1225 instantly rebooting without logging anything would be unfriendly.
1343 1226
1344 config VMAP_STACK 1227 config VMAP_STACK
1345 default y 1228 default y
1346 bool "Use a virtually-mapped stack" 1229 bool "Use a virtually-mapped stack"
1347 depends on HAVE_ARCH_VMAP_STACK 1230 depends on HAVE_ARCH_VMAP_STACK
1348 depends on !KASAN || KASAN_HW_TAGS || 1231 depends on !KASAN || KASAN_HW_TAGS || KASAN_VMALLOC
1349 help 1232 help
1350 Enable this if you want the use vir 1233 Enable this if you want the use virtually-mapped kernel stacks
1351 with guard pages. This causes kern 1234 with guard pages. This causes kernel stack overflows to be
1352 caught immediately rather than caus 1235 caught immediately rather than causing difficult-to-diagnose
1353 corruption. 1236 corruption.
1354 1237
1355 To use this with software KASAN mod 1238 To use this with software KASAN modes, the architecture must support
1356 backing virtual mappings with real 1239 backing virtual mappings with real shadow memory, and KASAN_VMALLOC
1357 must be enabled. 1240 must be enabled.
1358 1241
1359 config HAVE_ARCH_RANDOMIZE_KSTACK_OFFSET 1242 config HAVE_ARCH_RANDOMIZE_KSTACK_OFFSET
1360 def_bool n 1243 def_bool n
1361 help 1244 help
1362 An arch should select this symbol i 1245 An arch should select this symbol if it can support kernel stack
1363 offset randomization with calls to 1246 offset randomization with calls to add_random_kstack_offset()
1364 during syscall entry and choose_ran 1247 during syscall entry and choose_random_kstack_offset() during
1365 syscall exit. Careful removal of -f 1248 syscall exit. Careful removal of -fstack-protector-strong and
1366 -fstack-protector should also be ap 1249 -fstack-protector should also be applied to the entry code and
1367 closely examined, as the artificial 1250 closely examined, as the artificial stack bump looks like an array
1368 to the compiler, so it will attempt 1251 to the compiler, so it will attempt to add canary checks regardless
1369 of the static branch state. 1252 of the static branch state.
1370 1253
1371 config RANDOMIZE_KSTACK_OFFSET 1254 config RANDOMIZE_KSTACK_OFFSET
1372 bool "Support for randomizing kernel 1255 bool "Support for randomizing kernel stack offset on syscall entry" if EXPERT
1373 default y 1256 default y
1374 depends on HAVE_ARCH_RANDOMIZE_KSTACK 1257 depends on HAVE_ARCH_RANDOMIZE_KSTACK_OFFSET
1375 depends on INIT_STACK_NONE || !CC_IS_ 1258 depends on INIT_STACK_NONE || !CC_IS_CLANG || CLANG_VERSION >= 140000
1376 help 1259 help
1377 The kernel stack offset can be rand 1260 The kernel stack offset can be randomized (after pt_regs) by
1378 roughly 5 bits of entropy, frustrat 1261 roughly 5 bits of entropy, frustrating memory corruption
1379 attacks that depend on stack addres 1262 attacks that depend on stack address determinism or
1380 cross-syscall address exposures. 1263 cross-syscall address exposures.
1381 1264
1382 The feature is controlled via the " 1265 The feature is controlled via the "randomize_kstack_offset=on/off"
1383 kernel boot param, and if turned of 1266 kernel boot param, and if turned off has zero overhead due to its use
1384 of static branches (see JUMP_LABEL) 1267 of static branches (see JUMP_LABEL).
1385 1268
1386 If unsure, say Y. 1269 If unsure, say Y.
1387 1270
1388 config RANDOMIZE_KSTACK_OFFSET_DEFAULT 1271 config RANDOMIZE_KSTACK_OFFSET_DEFAULT
1389 bool "Default state of kernel stack o 1272 bool "Default state of kernel stack offset randomization"
1390 depends on RANDOMIZE_KSTACK_OFFSET 1273 depends on RANDOMIZE_KSTACK_OFFSET
1391 help 1274 help
1392 Kernel stack offset randomization i 1275 Kernel stack offset randomization is controlled by kernel boot param
1393 "randomize_kstack_offset=on/off", a 1276 "randomize_kstack_offset=on/off", and this config chooses the default
1394 boot state. 1277 boot state.
1395 1278
1396 config ARCH_OPTIONAL_KERNEL_RWX 1279 config ARCH_OPTIONAL_KERNEL_RWX
1397 def_bool n 1280 def_bool n
1398 1281
1399 config ARCH_OPTIONAL_KERNEL_RWX_DEFAULT 1282 config ARCH_OPTIONAL_KERNEL_RWX_DEFAULT
1400 def_bool n 1283 def_bool n
1401 1284
1402 config ARCH_HAS_STRICT_KERNEL_RWX 1285 config ARCH_HAS_STRICT_KERNEL_RWX
1403 def_bool n 1286 def_bool n
1404 1287
1405 config STRICT_KERNEL_RWX 1288 config STRICT_KERNEL_RWX
1406 bool "Make kernel text and rodata rea 1289 bool "Make kernel text and rodata read-only" if ARCH_OPTIONAL_KERNEL_RWX
1407 depends on ARCH_HAS_STRICT_KERNEL_RWX 1290 depends on ARCH_HAS_STRICT_KERNEL_RWX
1408 default !ARCH_OPTIONAL_KERNEL_RWX || 1291 default !ARCH_OPTIONAL_KERNEL_RWX || ARCH_OPTIONAL_KERNEL_RWX_DEFAULT
1409 help 1292 help
1410 If this is set, kernel text and rod 1293 If this is set, kernel text and rodata memory will be made read-only,
1411 and non-text memory will be made no 1294 and non-text memory will be made non-executable. This provides
1412 protection against certain security 1295 protection against certain security exploits (e.g. executing the heap
1413 or modifying text) 1296 or modifying text)
1414 1297
1415 These features are considered stand 1298 These features are considered standard security practice these days.
1416 You should say Y here in almost all 1299 You should say Y here in almost all cases.
1417 1300
1418 config ARCH_HAS_STRICT_MODULE_RWX 1301 config ARCH_HAS_STRICT_MODULE_RWX
1419 def_bool n 1302 def_bool n
1420 1303
1421 config STRICT_MODULE_RWX 1304 config STRICT_MODULE_RWX
1422 bool "Set loadable kernel module data 1305 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 1306 depends on ARCH_HAS_STRICT_MODULE_RWX && MODULES
1424 default !ARCH_OPTIONAL_KERNEL_RWX || 1307 default !ARCH_OPTIONAL_KERNEL_RWX || ARCH_OPTIONAL_KERNEL_RWX_DEFAULT
1425 help 1308 help
1426 If this is set, module text and rod 1309 If this is set, module text and rodata memory will be made read-only,
1427 and non-text memory will be made no 1310 and non-text memory will be made non-executable. This provides
1428 protection against certain security 1311 protection against certain security exploits (e.g. writing to text)
1429 1312
1430 # select if the architecture provides an asm/ 1313 # select if the architecture provides an asm/dma-direct.h header
1431 config ARCH_HAS_PHYS_TO_DMA 1314 config ARCH_HAS_PHYS_TO_DMA
1432 bool 1315 bool
1433 1316
1434 config HAVE_ARCH_COMPILER_H 1317 config HAVE_ARCH_COMPILER_H
1435 bool 1318 bool
1436 help 1319 help
1437 An architecture can select this if 1320 An architecture can select this if it provides an
1438 asm/compiler.h header that should b 1321 asm/compiler.h header that should be included after
1439 linux/compiler-*.h in order to over 1322 linux/compiler-*.h in order to override macro definitions that those
1440 headers generally provide. 1323 headers generally provide.
1441 1324
1442 config HAVE_ARCH_PREL32_RELOCATIONS 1325 config HAVE_ARCH_PREL32_RELOCATIONS
1443 bool 1326 bool
1444 help 1327 help
1445 May be selected by an architecture 1328 May be selected by an architecture if it supports place-relative
1446 32-bit relocations, both in the too 1329 32-bit relocations, both in the toolchain and in the module loader,
1447 in which case relative references c 1330 in which case relative references can be used in special sections
1448 for PCI fixup, initcalls etc which 1331 for PCI fixup, initcalls etc which are only half the size on 64 bit
1449 architectures, and don't require ru 1332 architectures, and don't require runtime relocation on relocatable
1450 kernels. 1333 kernels.
1451 1334
1452 config ARCH_USE_MEMREMAP_PROT 1335 config ARCH_USE_MEMREMAP_PROT
1453 bool 1336 bool
1454 1337
1455 config LOCK_EVENT_COUNTS 1338 config LOCK_EVENT_COUNTS
1456 bool "Locking event counts collection 1339 bool "Locking event counts collection"
1457 depends on DEBUG_FS 1340 depends on DEBUG_FS
1458 help 1341 help
1459 Enable light-weight counting of var 1342 Enable light-weight counting of various locking related events
1460 in the system with minimal performa 1343 in the system with minimal performance impact. This reduces
1461 the chance of application behavior 1344 the chance of application behavior change because of timing
1462 differences. The counts are reporte 1345 differences. The counts are reported via debugfs.
1463 1346
1464 # Select if the architecture has support for 1347 # Select if the architecture has support for applying RELR relocations.
1465 config ARCH_HAS_RELR 1348 config ARCH_HAS_RELR
1466 bool 1349 bool
1467 1350
1468 config RELR 1351 config RELR
1469 bool "Use RELR relocation packing" 1352 bool "Use RELR relocation packing"
1470 depends on ARCH_HAS_RELR && TOOLS_SUP 1353 depends on ARCH_HAS_RELR && TOOLS_SUPPORT_RELR
1471 default y 1354 default y
1472 help 1355 help
1473 Store the kernel's dynamic relocati 1356 Store the kernel's dynamic relocations in the RELR relocation packing
1474 format. Requires a compatible linke 1357 format. Requires a compatible linker (LLD supports this feature), as
1475 well as compatible NM and OBJCOPY u 1358 well as compatible NM and OBJCOPY utilities (llvm-nm and llvm-objcopy
1476 are compatible). 1359 are compatible).
1477 1360
1478 config ARCH_HAS_MEM_ENCRYPT 1361 config ARCH_HAS_MEM_ENCRYPT
1479 bool 1362 bool
1480 1363
1481 config ARCH_HAS_CC_PLATFORM 1364 config ARCH_HAS_CC_PLATFORM
1482 bool 1365 bool
1483 1366
1484 config HAVE_SPARSE_SYSCALL_NR 1367 config HAVE_SPARSE_SYSCALL_NR
1485 bool 1368 bool
1486 help 1369 help
1487 An architecture should select this 1370 An architecture should select this if its syscall numbering is sparse
1488 to save space. For example, MIPS ar 1371 to save space. For example, MIPS architecture has a syscall array with
1489 entries at 4000, 5000 and 6000 loca 1372 entries at 4000, 5000 and 6000 locations. This option turns on syscall
1490 related optimizations for a given a 1373 related optimizations for a given architecture.
1491 1374
1492 config ARCH_HAS_VDSO_DATA 1375 config ARCH_HAS_VDSO_DATA
1493 bool 1376 bool
1494 1377
1495 config HAVE_STATIC_CALL 1378 config HAVE_STATIC_CALL
1496 bool 1379 bool
1497 1380
1498 config HAVE_STATIC_CALL_INLINE 1381 config HAVE_STATIC_CALL_INLINE
1499 bool 1382 bool
1500 depends on HAVE_STATIC_CALL 1383 depends on HAVE_STATIC_CALL
1501 select OBJTOOL 1384 select OBJTOOL
1502 1385
1503 config HAVE_PREEMPT_DYNAMIC 1386 config HAVE_PREEMPT_DYNAMIC
1504 bool 1387 bool
1505 1388
1506 config HAVE_PREEMPT_DYNAMIC_CALL 1389 config HAVE_PREEMPT_DYNAMIC_CALL
1507 bool 1390 bool
1508 depends on HAVE_STATIC_CALL 1391 depends on HAVE_STATIC_CALL
1509 select HAVE_PREEMPT_DYNAMIC 1392 select HAVE_PREEMPT_DYNAMIC
1510 help 1393 help
1511 An architecture should select this 1394 An architecture should select this if it can handle the preemption
1512 model being selected at boot time u 1395 model being selected at boot time using static calls.
1513 1396
1514 Where an architecture selects HAVE_ 1397 Where an architecture selects HAVE_STATIC_CALL_INLINE, any call to a
1515 preemption function will be patched 1398 preemption function will be patched directly.
1516 1399
1517 Where an architecture does not sele 1400 Where an architecture does not select HAVE_STATIC_CALL_INLINE, any
1518 call to a preemption function will 1401 call to a preemption function will go through a trampoline, and the
1519 trampoline will be patched. 1402 trampoline will be patched.
1520 1403
1521 It is strongly advised to support i 1404 It is strongly advised to support inline static call to avoid any
1522 overhead. 1405 overhead.
1523 1406
1524 config HAVE_PREEMPT_DYNAMIC_KEY 1407 config HAVE_PREEMPT_DYNAMIC_KEY
1525 bool 1408 bool
1526 depends on HAVE_ARCH_JUMP_LABEL 1409 depends on HAVE_ARCH_JUMP_LABEL
1527 select HAVE_PREEMPT_DYNAMIC 1410 select HAVE_PREEMPT_DYNAMIC
1528 help 1411 help
1529 An architecture should select this 1412 An architecture should select this if it can handle the preemption
1530 model being selected at boot time u 1413 model being selected at boot time using static keys.
1531 1414
1532 Each preemption function will be gi 1415 Each preemption function will be given an early return based on a
1533 static key. This should have slight 1416 static key. This should have slightly lower overhead than non-inline
1534 static calls, as this effectively i 1417 static calls, as this effectively inlines each trampoline into the
1535 start of its callee. This may avoid 1418 start of its callee. This may avoid redundant work, and may
1536 integrate better with CFI schemes. 1419 integrate better with CFI schemes.
1537 1420
1538 This will have greater overhead tha 1421 This will have greater overhead than using inline static calls as
1539 the call to the preemption function 1422 the call to the preemption function cannot be entirely elided.
1540 1423
1541 config ARCH_WANT_LD_ORPHAN_WARN 1424 config ARCH_WANT_LD_ORPHAN_WARN
1542 bool 1425 bool
1543 help 1426 help
1544 An arch should select this symbol o 1427 An arch should select this symbol once all linker sections are explicitly
1545 included, size-asserted, or discard 1428 included, size-asserted, or discarded in the linker scripts. This is
1546 important because we never want exp 1429 important because we never want expected sections to be placed heuristically
1547 by the linker, since the locations 1430 by the linker, since the locations of such sections can change between linker
1548 versions. 1431 versions.
1549 1432
1550 config HAVE_ARCH_PFN_VALID 1433 config HAVE_ARCH_PFN_VALID
1551 bool 1434 bool
1552 1435
1553 config ARCH_SUPPORTS_DEBUG_PAGEALLOC 1436 config ARCH_SUPPORTS_DEBUG_PAGEALLOC
1554 bool 1437 bool
1555 1438
1556 config ARCH_SUPPORTS_PAGE_TABLE_CHECK 1439 config ARCH_SUPPORTS_PAGE_TABLE_CHECK
1557 bool 1440 bool
1558 1441
1559 config ARCH_SPLIT_ARG64 1442 config ARCH_SPLIT_ARG64
1560 bool 1443 bool
1561 help 1444 help
1562 If a 32-bit architecture requires 6 1445 If a 32-bit architecture requires 64-bit arguments to be split into
1563 pairs of 32-bit arguments, select t 1446 pairs of 32-bit arguments, select this option.
1564 1447
1565 config ARCH_HAS_ELFCORE_COMPAT 1448 config ARCH_HAS_ELFCORE_COMPAT
1566 bool 1449 bool
1567 1450
1568 config ARCH_HAS_PARANOID_L1D_FLUSH 1451 config ARCH_HAS_PARANOID_L1D_FLUSH
1569 bool 1452 bool
1570 1453
1571 config ARCH_HAVE_TRACE_MMIO_ACCESS 1454 config ARCH_HAVE_TRACE_MMIO_ACCESS
1572 bool 1455 bool
1573 1456
1574 config DYNAMIC_SIGFRAME 1457 config DYNAMIC_SIGFRAME
1575 bool 1458 bool
1576 1459
1577 # Select, if arch has a named attribute group 1460 # Select, if arch has a named attribute group bound to NUMA device nodes.
1578 config HAVE_ARCH_NODE_DEV_GROUP 1461 config HAVE_ARCH_NODE_DEV_GROUP
1579 bool 1462 bool
1580 1463
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 1464 config ARCH_HAS_NONLEAF_PMD_YOUNG
1590 bool 1465 bool
1591 help 1466 help
1592 Architectures that select this opti 1467 Architectures that select this option are capable of setting the
1593 accessed bit in non-leaf PMD entrie 1468 accessed bit in non-leaf PMD entries when using them as part of linear
1594 address translations. Page table wa 1469 address translations. Page table walkers that clear the accessed bit
1595 may use this capability to reduce t 1470 may use this capability to reduce their search space.
1596 1471
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" 1472 source "kernel/gcov/Kconfig"
1604 1473
1605 source "scripts/gcc-plugins/Kconfig" 1474 source "scripts/gcc-plugins/Kconfig"
1606 1475
1607 config FUNCTION_ALIGNMENT_4B 1476 config FUNCTION_ALIGNMENT_4B
1608 bool 1477 bool
1609 1478
1610 config FUNCTION_ALIGNMENT_8B 1479 config FUNCTION_ALIGNMENT_8B
1611 bool 1480 bool
1612 1481
1613 config FUNCTION_ALIGNMENT_16B 1482 config FUNCTION_ALIGNMENT_16B
1614 bool 1483 bool
1615 1484
1616 config FUNCTION_ALIGNMENT_32B 1485 config FUNCTION_ALIGNMENT_32B
1617 bool 1486 bool
1618 1487
1619 config FUNCTION_ALIGNMENT_64B 1488 config FUNCTION_ALIGNMENT_64B
1620 bool 1489 bool
1621 1490
1622 config FUNCTION_ALIGNMENT 1491 config FUNCTION_ALIGNMENT
1623 int 1492 int
1624 default 64 if FUNCTION_ALIGNMENT_64B 1493 default 64 if FUNCTION_ALIGNMENT_64B
1625 default 32 if FUNCTION_ALIGNMENT_32B 1494 default 32 if FUNCTION_ALIGNMENT_32B
1626 default 16 if FUNCTION_ALIGNMENT_16B 1495 default 16 if FUNCTION_ALIGNMENT_16B
1627 default 8 if FUNCTION_ALIGNMENT_8B 1496 default 8 if FUNCTION_ALIGNMENT_8B
1628 default 4 if FUNCTION_ALIGNMENT_4B 1497 default 4 if FUNCTION_ALIGNMENT_4B
1629 default 0 1498 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 1499
1646 endmenu 1500 endmenu
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