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 !! 12 menu "General architecture-dependent options"
>> 13
>> 14 config CRASH_CORE
13 bool 15 bool
14 16
15 if !ARCH_CONFIGURES_CPU_MITIGATIONS !! 17 config KEXEC_CORE
16 config CPU_MITIGATIONS !! 18 select CRASH_CORE
17 def_bool y !! 19 bool
18 endif <<
19 20
20 # !! 21 config KEXEC_ELF
21 # Selected by architectures that need custom D <<
22 # IOMMUs not handled by dma-iommu. Drivers mu <<
23 # <<
24 config ARCH_HAS_DMA_OPS <<
25 depends on HAS_DMA <<
26 select DMA_OPS_HELPERS <<
27 bool 22 bool
28 23
29 menu "General architecture-dependent options" !! 24 config HAVE_IMA_KEXEC
>> 25 bool
30 26
31 config ARCH_HAS_SUBPAGE_FAULTS 27 config ARCH_HAS_SUBPAGE_FAULTS
32 bool 28 bool
33 help 29 help
34 Select if the architecture can check 30 Select if the architecture can check permissions at sub-page
35 granularity (e.g. arm64 MTE). The pr 31 granularity (e.g. arm64 MTE). The probe_user_*() functions
36 must be implemented. 32 must be implemented.
37 33
38 config HOTPLUG_SMT 34 config HOTPLUG_SMT
39 bool 35 bool
40 36
41 config SMT_NUM_THREADS_DYNAMIC <<
42 bool <<
43 <<
44 # Selected by HOTPLUG_CORE_SYNC_DEAD or HOTPLU <<
45 config HOTPLUG_CORE_SYNC <<
46 bool <<
47 <<
48 # Basic CPU dead synchronization selected by a <<
49 config HOTPLUG_CORE_SYNC_DEAD <<
50 bool <<
51 select HOTPLUG_CORE_SYNC <<
52 <<
53 # Full CPU synchronization with alive state se <<
54 config HOTPLUG_CORE_SYNC_FULL <<
55 bool <<
56 select HOTPLUG_CORE_SYNC_DEAD if HOTPL <<
57 select HOTPLUG_CORE_SYNC <<
58 <<
59 config HOTPLUG_SPLIT_STARTUP <<
60 bool <<
61 select HOTPLUG_CORE_SYNC_FULL <<
62 <<
63 config HOTPLUG_PARALLEL <<
64 bool <<
65 select HOTPLUG_SPLIT_STARTUP <<
66 <<
67 config GENERIC_ENTRY 37 config GENERIC_ENTRY
68 bool 38 bool
69 39
70 config KPROBES 40 config KPROBES
71 bool "Kprobes" 41 bool "Kprobes"
>> 42 depends on MODULES
72 depends on HAVE_KPROBES 43 depends on HAVE_KPROBES
73 select KALLSYMS 44 select KALLSYMS
74 select EXECMEM !! 45 select TASKS_RCU if PREEMPTION
75 select NEED_TASKS_RCU <<
76 help 46 help
77 Kprobes allows you to trap at almost 47 Kprobes allows you to trap at almost any kernel address and
78 execute a callback function. regist 48 execute a callback function. register_kprobe() establishes
79 a probepoint and specifies the callb 49 a probepoint and specifies the callback. Kprobes is useful
80 for kernel debugging, non-intrusive 50 for kernel debugging, non-intrusive instrumentation and testing.
81 If in doubt, say "N". 51 If in doubt, say "N".
82 52
83 config JUMP_LABEL 53 config JUMP_LABEL
84 bool "Optimize very unlikely/likely br 54 bool "Optimize very unlikely/likely branches"
85 depends on HAVE_ARCH_JUMP_LABEL 55 depends on HAVE_ARCH_JUMP_LABEL
86 select OBJTOOL if HAVE_JUMP_LABEL_HACK 56 select OBJTOOL if HAVE_JUMP_LABEL_HACK
87 help 57 help
88 This option enables a transparent br 58 This option enables a transparent branch optimization that
89 makes certain almost-always-true or 59 makes certain almost-always-true or almost-always-false branch
90 conditions even cheaper to execute w 60 conditions even cheaper to execute within the kernel.
91 61
92 Certain performance-sensitive kernel 62 Certain performance-sensitive kernel code, such as trace points,
93 scheduler functionality, networking 63 scheduler functionality, networking code and KVM have such
94 branches and include support for thi 64 branches and include support for this optimization technique.
95 65
96 If it is detected that the compiler 66 If it is detected that the compiler has support for "asm goto",
97 the kernel will compile such branche 67 the kernel will compile such branches with just a nop
98 instruction. When the condition flag 68 instruction. When the condition flag is toggled to true, the
99 nop will be converted to a jump inst 69 nop will be converted to a jump instruction to execute the
100 conditional block of instructions. 70 conditional block of instructions.
101 71
102 This technique lowers overhead and s 72 This technique lowers overhead and stress on the branch prediction
103 of the processor and generally makes 73 of the processor and generally makes the kernel faster. The update
104 of the condition is slower, but thos 74 of the condition is slower, but those are always very rare.
105 75
106 ( On 32-bit x86, the necessary optio 76 ( On 32-bit x86, the necessary options added to the compiler
107 flags may increase the size of the 77 flags may increase the size of the kernel slightly. )
108 78
109 config STATIC_KEYS_SELFTEST 79 config STATIC_KEYS_SELFTEST
110 bool "Static key selftest" 80 bool "Static key selftest"
111 depends on JUMP_LABEL 81 depends on JUMP_LABEL
112 help 82 help
113 Boot time self-test of the branch pa 83 Boot time self-test of the branch patching code.
114 84
115 config STATIC_CALL_SELFTEST 85 config STATIC_CALL_SELFTEST
116 bool "Static call selftest" 86 bool "Static call selftest"
117 depends on HAVE_STATIC_CALL 87 depends on HAVE_STATIC_CALL
118 help 88 help
119 Boot time self-test of the call patc 89 Boot time self-test of the call patching code.
120 90
121 config OPTPROBES 91 config OPTPROBES
122 def_bool y 92 def_bool y
123 depends on KPROBES && HAVE_OPTPROBES 93 depends on KPROBES && HAVE_OPTPROBES
124 select NEED_TASKS_RCU !! 94 select TASKS_RCU if PREEMPTION
125 95
126 config KPROBES_ON_FTRACE 96 config KPROBES_ON_FTRACE
127 def_bool y 97 def_bool y
128 depends on KPROBES && HAVE_KPROBES_ON_ 98 depends on KPROBES && HAVE_KPROBES_ON_FTRACE
129 depends on DYNAMIC_FTRACE_WITH_REGS 99 depends on DYNAMIC_FTRACE_WITH_REGS
130 help 100 help
131 If function tracer is enabled and th 101 If function tracer is enabled and the arch supports full
132 passing of pt_regs to function traci 102 passing of pt_regs to function tracing, then kprobes can
133 optimize on top of function tracing. 103 optimize on top of function tracing.
134 104
135 config UPROBES 105 config UPROBES
136 def_bool n 106 def_bool n
137 depends on ARCH_SUPPORTS_UPROBES 107 depends on ARCH_SUPPORTS_UPROBES
138 help 108 help
139 Uprobes is the user-space counterpar 109 Uprobes is the user-space counterpart to kprobes: they
140 enable instrumentation applications 110 enable instrumentation applications (such as 'perf probe')
141 to establish unintrusive probes in u 111 to establish unintrusive probes in user-space binaries and
142 libraries, by executing handler func 112 libraries, by executing handler functions when the probes
143 are hit by user-space applications. 113 are hit by user-space applications.
144 114
145 ( These probes come in the form of s 115 ( These probes come in the form of single-byte breakpoints,
146 managed by the kernel and kept tra 116 managed by the kernel and kept transparent to the probed
147 application. ) 117 application. )
148 118
149 config HAVE_64BIT_ALIGNED_ACCESS 119 config HAVE_64BIT_ALIGNED_ACCESS
150 def_bool 64BIT && !HAVE_EFFICIENT_UNAL 120 def_bool 64BIT && !HAVE_EFFICIENT_UNALIGNED_ACCESS
151 help 121 help
152 Some architectures require 64 bit ac 122 Some architectures require 64 bit accesses to be 64 bit
153 aligned, which also requires structs 123 aligned, which also requires structs containing 64 bit values
154 to be 64 bit aligned too. This inclu 124 to be 64 bit aligned too. This includes some 32 bit
155 architectures which can do 64 bit ac 125 architectures which can do 64 bit accesses, as well as 64 bit
156 architectures without unaligned acce 126 architectures without unaligned access.
157 127
158 This symbol should be selected by an 128 This symbol should be selected by an architecture if 64 bit
159 accesses are required to be 64 bit a 129 accesses are required to be 64 bit aligned in this way even
160 though it is not a 64 bit architectu 130 though it is not a 64 bit architecture.
161 131
162 See Documentation/core-api/unaligned 132 See Documentation/core-api/unaligned-memory-access.rst for
163 more information on the topic of una 133 more information on the topic of unaligned memory accesses.
164 134
165 config HAVE_EFFICIENT_UNALIGNED_ACCESS 135 config HAVE_EFFICIENT_UNALIGNED_ACCESS
166 bool 136 bool
167 help 137 help
168 Some architectures are unable to per 138 Some architectures are unable to perform unaligned accesses
169 without the use of get_unaligned/put 139 without the use of get_unaligned/put_unaligned. Others are
170 unable to perform such accesses effi 140 unable to perform such accesses efficiently (e.g. trap on
171 unaligned access and require fixing 141 unaligned access and require fixing it up in the exception
172 handler.) 142 handler.)
173 143
174 This symbol should be selected by an 144 This symbol should be selected by an architecture if it can
175 perform unaligned accesses efficient 145 perform unaligned accesses efficiently to allow different
176 code paths to be selected for these 146 code paths to be selected for these cases. Some network
177 drivers, for example, could opt to n 147 drivers, for example, could opt to not fix up alignment
178 problems with received packets if do 148 problems with received packets if doing so would not help
179 much. 149 much.
180 150
181 See Documentation/core-api/unaligned 151 See Documentation/core-api/unaligned-memory-access.rst for more
182 information on the topic of unaligne 152 information on the topic of unaligned memory accesses.
183 153
184 config ARCH_USE_BUILTIN_BSWAP 154 config ARCH_USE_BUILTIN_BSWAP
185 bool 155 bool
186 help 156 help
187 Modern versions of GCC (since 4.4) h 157 Modern versions of GCC (since 4.4) have builtin functions
188 for handling byte-swapping. Using th 158 for handling byte-swapping. Using these, instead of the old
189 inline assembler that the architectu 159 inline assembler that the architecture code provides in the
190 __arch_bswapXX() macros, allows the 160 __arch_bswapXX() macros, allows the compiler to see what's
191 happening and offers more opportunit 161 happening and offers more opportunity for optimisation. In
192 particular, the compiler will be abl 162 particular, the compiler will be able to combine the byteswap
193 with a nearby load or store and use 163 with a nearby load or store and use load-and-swap or
194 store-and-swap instructions if the a 164 store-and-swap instructions if the architecture has them. It
195 should almost *never* result in code 165 should almost *never* result in code which is worse than the
196 hand-coded assembler in <asm/swab.h> 166 hand-coded assembler in <asm/swab.h>. But just in case it
197 does, the use of the builtins is opt 167 does, the use of the builtins is optional.
198 168
199 Any architecture with load-and-swap 169 Any architecture with load-and-swap or store-and-swap
200 instructions should set this. And it 170 instructions should set this. And it shouldn't hurt to set it
201 on architectures that don't have suc 171 on architectures that don't have such instructions.
202 172
203 config KRETPROBES 173 config KRETPROBES
204 def_bool y 174 def_bool y
205 depends on KPROBES && (HAVE_KRETPROBES 175 depends on KPROBES && (HAVE_KRETPROBES || HAVE_RETHOOK)
206 176
207 config KRETPROBE_ON_RETHOOK 177 config KRETPROBE_ON_RETHOOK
208 def_bool y 178 def_bool y
209 depends on HAVE_RETHOOK 179 depends on HAVE_RETHOOK
210 depends on KRETPROBES 180 depends on KRETPROBES
211 select RETHOOK 181 select RETHOOK
212 182
213 config USER_RETURN_NOTIFIER 183 config USER_RETURN_NOTIFIER
214 bool 184 bool
215 depends on HAVE_USER_RETURN_NOTIFIER 185 depends on HAVE_USER_RETURN_NOTIFIER
216 help 186 help
217 Provide a kernel-internal notificati 187 Provide a kernel-internal notification when a cpu is about to
218 switch to user mode. 188 switch to user mode.
219 189
220 config HAVE_IOREMAP_PROT 190 config HAVE_IOREMAP_PROT
221 bool 191 bool
222 192
223 config HAVE_KPROBES 193 config HAVE_KPROBES
224 bool 194 bool
225 195
226 config HAVE_KRETPROBES 196 config HAVE_KRETPROBES
227 bool 197 bool
228 198
229 config HAVE_OPTPROBES 199 config HAVE_OPTPROBES
230 bool 200 bool
231 201
232 config HAVE_KPROBES_ON_FTRACE 202 config HAVE_KPROBES_ON_FTRACE
233 bool 203 bool
234 204
235 config ARCH_CORRECT_STACKTRACE_ON_KRETPROBE 205 config ARCH_CORRECT_STACKTRACE_ON_KRETPROBE
236 bool 206 bool
237 help 207 help
238 Since kretprobes modifies return add 208 Since kretprobes modifies return address on the stack, the
239 stacktrace may see the kretprobe tra 209 stacktrace may see the kretprobe trampoline address instead
240 of correct one. If the architecture 210 of correct one. If the architecture stacktrace code and
241 unwinder can adjust such entries, se 211 unwinder can adjust such entries, select this configuration.
242 212
243 config HAVE_FUNCTION_ERROR_INJECTION 213 config HAVE_FUNCTION_ERROR_INJECTION
244 bool 214 bool
245 215
246 config HAVE_NMI 216 config HAVE_NMI
247 bool 217 bool
248 218
249 config HAVE_FUNCTION_DESCRIPTORS 219 config HAVE_FUNCTION_DESCRIPTORS
250 bool 220 bool
251 221
252 config TRACE_IRQFLAGS_SUPPORT 222 config TRACE_IRQFLAGS_SUPPORT
253 bool 223 bool
254 224
255 config TRACE_IRQFLAGS_NMI_SUPPORT 225 config TRACE_IRQFLAGS_NMI_SUPPORT
256 bool 226 bool
257 227
258 # 228 #
259 # An arch should select this if it provides al 229 # An arch should select this if it provides all these things:
260 # 230 #
261 # task_pt_regs() in asm/process 231 # task_pt_regs() in asm/processor.h or asm/ptrace.h
262 # arch_has_single_step() if there is ha 232 # arch_has_single_step() if there is hardware single-step support
263 # arch_has_block_step() if there is ha 233 # arch_has_block_step() if there is hardware block-step support
264 # asm/syscall.h supplying asm- 234 # asm/syscall.h supplying asm-generic/syscall.h interface
265 # linux/regset.h user_regset in 235 # linux/regset.h user_regset interfaces
266 # CORE_DUMP_USE_REGSET #define'd in l 236 # CORE_DUMP_USE_REGSET #define'd in linux/elf.h
267 # TIF_SYSCALL_TRACE calls ptrace_r 237 # TIF_SYSCALL_TRACE calls ptrace_report_syscall_{entry,exit}
268 # TIF_NOTIFY_RESUME calls resume_u 238 # TIF_NOTIFY_RESUME calls resume_user_mode_work()
269 # 239 #
270 config HAVE_ARCH_TRACEHOOK 240 config HAVE_ARCH_TRACEHOOK
271 bool 241 bool
272 242
273 config HAVE_DMA_CONTIGUOUS 243 config HAVE_DMA_CONTIGUOUS
274 bool 244 bool
275 245
276 config GENERIC_SMP_IDLE_THREAD 246 config GENERIC_SMP_IDLE_THREAD
277 bool 247 bool
278 248
279 config GENERIC_IDLE_POLL_SETUP 249 config GENERIC_IDLE_POLL_SETUP
280 bool 250 bool
281 251
282 config ARCH_HAS_FORTIFY_SOURCE 252 config ARCH_HAS_FORTIFY_SOURCE
283 bool 253 bool
284 help 254 help
285 An architecture should select this w 255 An architecture should select this when it can successfully
286 build and run with CONFIG_FORTIFY_SO 256 build and run with CONFIG_FORTIFY_SOURCE.
287 257
288 # 258 #
289 # Select if the arch provides a historic keepi 259 # Select if the arch provides a historic keepinit alias for the retain_initrd
290 # command line option 260 # command line option
291 # 261 #
292 config ARCH_HAS_KEEPINITRD 262 config ARCH_HAS_KEEPINITRD
293 bool 263 bool
294 264
295 # 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
296 config ARCH_HAS_SET_MEMORY 266 config ARCH_HAS_SET_MEMORY
297 bool 267 bool
298 268
299 # Select if arch has all set_direct_map_invali 269 # Select if arch has all set_direct_map_invalid/default() functions
300 config ARCH_HAS_SET_DIRECT_MAP 270 config ARCH_HAS_SET_DIRECT_MAP
301 bool 271 bool
302 272
303 # 273 #
304 # Select if the architecture provides the arch 274 # Select if the architecture provides the arch_dma_set_uncached symbol to
305 # either provide an uncached segment alias for 275 # either provide an uncached segment alias for a DMA allocation, or
306 # to remap the page tables in place. 276 # to remap the page tables in place.
307 # 277 #
308 config ARCH_HAS_DMA_SET_UNCACHED 278 config ARCH_HAS_DMA_SET_UNCACHED
309 bool 279 bool
310 280
311 # 281 #
312 # Select if the architectures provides the arc 282 # Select if the architectures provides the arch_dma_clear_uncached symbol
313 # to undo an in-place page table remap for unc 283 # to undo an in-place page table remap for uncached access.
314 # 284 #
315 config ARCH_HAS_DMA_CLEAR_UNCACHED 285 config ARCH_HAS_DMA_CLEAR_UNCACHED
316 bool 286 bool
317 287
318 config ARCH_HAS_CPU_FINALIZE_INIT 288 config ARCH_HAS_CPU_FINALIZE_INIT
319 bool 289 bool
320 290
321 # The architecture has a per-task state that i !! 291 # Select if arch init_task must go in the __init_task_data section
322 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
323 bool 297 bool
324 select IOMMU_MM_DATA <<
325 298
326 config HAVE_ARCH_THREAD_STRUCT_WHITELIST 299 config HAVE_ARCH_THREAD_STRUCT_WHITELIST
327 bool 300 bool
>> 301 depends on !ARCH_TASK_STRUCT_ALLOCATOR
328 help 302 help
329 An architecture should select this t 303 An architecture should select this to provide hardened usercopy
330 knowledge about what region of the t 304 knowledge about what region of the thread_struct should be
331 whitelisted for copying to userspace 305 whitelisted for copying to userspace. Normally this is only the
332 FPU registers. Specifically, arch_th 306 FPU registers. Specifically, arch_thread_struct_whitelist()
333 should be implemented. Without this, 307 should be implemented. Without this, the entire thread_struct
334 field in task_struct will be left wh 308 field in task_struct will be left whitelisted.
335 309
>> 310 # Select if arch has its private alloc_thread_stack() function
>> 311 config ARCH_THREAD_STACK_ALLOCATOR
>> 312 bool
>> 313
336 # Select if arch wants to size task_struct dyn 314 # Select if arch wants to size task_struct dynamically via arch_task_struct_size:
337 config ARCH_WANTS_DYNAMIC_TASK_STRUCT 315 config ARCH_WANTS_DYNAMIC_TASK_STRUCT
338 bool 316 bool
339 317
340 config ARCH_WANTS_NO_INSTR 318 config ARCH_WANTS_NO_INSTR
341 bool 319 bool
342 help 320 help
343 An architecture should select this i 321 An architecture should select this if the noinstr macro is being used on
344 functions to denote that the toolcha 322 functions to denote that the toolchain should avoid instrumenting such
345 functions and is required for correc 323 functions and is required for correctness.
346 324
347 config ARCH_32BIT_OFF_T 325 config ARCH_32BIT_OFF_T
348 bool 326 bool
349 depends on !64BIT 327 depends on !64BIT
350 help 328 help
351 All new 32-bit architectures should 329 All new 32-bit architectures should have 64-bit off_t type on
352 userspace side which corresponds to 330 userspace side which corresponds to the loff_t kernel type. This
353 is the requirement for modern ABIs. 331 is the requirement for modern ABIs. Some existing architectures
354 still support 32-bit off_t. This opt 332 still support 32-bit off_t. This option is enabled for all such
355 architectures explicitly. 333 architectures explicitly.
356 334
357 # Selected by 64 bit architectures which have 335 # Selected by 64 bit architectures which have a 32 bit f_tinode in struct ustat
358 config ARCH_32BIT_USTAT_F_TINODE 336 config ARCH_32BIT_USTAT_F_TINODE
359 bool 337 bool
360 338
361 config HAVE_ASM_MODVERSIONS 339 config HAVE_ASM_MODVERSIONS
362 bool 340 bool
363 help 341 help
364 This symbol should be selected by an 342 This symbol should be selected by an architecture if it provides
365 <asm/asm-prototypes.h> to support th 343 <asm/asm-prototypes.h> to support the module versioning for symbols
366 exported from assembly code. 344 exported from assembly code.
367 345
368 config HAVE_REGS_AND_STACK_ACCESS_API 346 config HAVE_REGS_AND_STACK_ACCESS_API
369 bool 347 bool
370 help 348 help
371 This symbol should be selected by an 349 This symbol should be selected by an architecture if it supports
372 the API needed to access registers a 350 the API needed to access registers and stack entries from pt_regs,
373 declared in asm/ptrace.h 351 declared in asm/ptrace.h
374 For example the kprobes-based event 352 For example the kprobes-based event tracer needs this API.
375 353
376 config HAVE_RSEQ 354 config HAVE_RSEQ
377 bool 355 bool
378 depends on HAVE_REGS_AND_STACK_ACCESS_ 356 depends on HAVE_REGS_AND_STACK_ACCESS_API
379 help 357 help
380 This symbol should be selected by an 358 This symbol should be selected by an architecture if it
381 supports an implementation of restar 359 supports an implementation of restartable sequences.
382 360
383 config HAVE_RUST 361 config HAVE_RUST
384 bool 362 bool
385 help 363 help
386 This symbol should be selected by an 364 This symbol should be selected by an architecture if it
387 supports Rust. 365 supports Rust.
388 366
389 config HAVE_FUNCTION_ARG_ACCESS_API 367 config HAVE_FUNCTION_ARG_ACCESS_API
390 bool 368 bool
391 help 369 help
392 This symbol should be selected by an 370 This symbol should be selected by an architecture if it supports
393 the API needed to access function ar 371 the API needed to access function arguments from pt_regs,
394 declared in asm/ptrace.h 372 declared in asm/ptrace.h
395 373
396 config HAVE_HW_BREAKPOINT 374 config HAVE_HW_BREAKPOINT
397 bool 375 bool
398 depends on PERF_EVENTS 376 depends on PERF_EVENTS
399 377
400 config HAVE_MIXED_BREAKPOINTS_REGS 378 config HAVE_MIXED_BREAKPOINTS_REGS
401 bool 379 bool
402 depends on HAVE_HW_BREAKPOINT 380 depends on HAVE_HW_BREAKPOINT
403 help 381 help
404 Depending on the arch implementation 382 Depending on the arch implementation of hardware breakpoints,
405 some of them have separate registers 383 some of them have separate registers for data and instruction
406 breakpoints addresses, others have m 384 breakpoints addresses, others have mixed registers to store
407 them but define the access type in a 385 them but define the access type in a control register.
408 Select this option if your arch impl 386 Select this option if your arch implements breakpoints under the
409 latter fashion. 387 latter fashion.
410 388
411 config HAVE_USER_RETURN_NOTIFIER 389 config HAVE_USER_RETURN_NOTIFIER
412 bool 390 bool
413 391
414 config HAVE_PERF_EVENTS_NMI 392 config HAVE_PERF_EVENTS_NMI
415 bool 393 bool
416 help 394 help
417 System hardware can generate an NMI 395 System hardware can generate an NMI using the perf event
418 subsystem. Also has support for cal 396 subsystem. Also has support for calculating CPU cycle events
419 to determine how many clock cycles i 397 to determine how many clock cycles in a given period.
420 398
421 config HAVE_HARDLOCKUP_DETECTOR_PERF 399 config HAVE_HARDLOCKUP_DETECTOR_PERF
422 bool 400 bool
423 depends on HAVE_PERF_EVENTS_NMI 401 depends on HAVE_PERF_EVENTS_NMI
424 help 402 help
425 The arch chooses to use the generic 403 The arch chooses to use the generic perf-NMI-based hardlockup
426 detector. Must define HAVE_PERF_EVEN 404 detector. Must define HAVE_PERF_EVENTS_NMI.
427 405
428 config HAVE_HARDLOCKUP_DETECTOR_ARCH !! 406 config HAVE_NMI_WATCHDOG
>> 407 depends on HAVE_NMI
429 bool 408 bool
430 help 409 help
431 The arch provides its own hardlockup !! 410 The arch provides a low level NMI watchdog. It provides
432 of the generic ones. !! 411 asm/nmi.h, and defines its own arch_touch_nmi_watchdog().
433 412
434 It uses the same command line parame !! 413 config HAVE_HARDLOCKUP_DETECTOR_ARCH
435 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.
436 420
437 config HAVE_PERF_REGS 421 config HAVE_PERF_REGS
438 bool 422 bool
439 help 423 help
440 Support selective register dumps for 424 Support selective register dumps for perf events. This includes
441 bit-mapping of each registers and a 425 bit-mapping of each registers and a unique architecture id.
442 426
443 config HAVE_PERF_USER_STACK_DUMP 427 config HAVE_PERF_USER_STACK_DUMP
444 bool 428 bool
445 help 429 help
446 Support user stack dumps for perf ev 430 Support user stack dumps for perf event samples. This needs
447 access to the user stack pointer whi 431 access to the user stack pointer which is not unified across
448 architectures. 432 architectures.
449 433
450 config HAVE_ARCH_JUMP_LABEL 434 config HAVE_ARCH_JUMP_LABEL
451 bool 435 bool
452 436
453 config HAVE_ARCH_JUMP_LABEL_RELATIVE 437 config HAVE_ARCH_JUMP_LABEL_RELATIVE
454 bool 438 bool
455 439
456 config MMU_GATHER_TABLE_FREE 440 config MMU_GATHER_TABLE_FREE
457 bool 441 bool
458 442
459 config MMU_GATHER_RCU_TABLE_FREE 443 config MMU_GATHER_RCU_TABLE_FREE
460 bool 444 bool
461 select MMU_GATHER_TABLE_FREE 445 select MMU_GATHER_TABLE_FREE
462 446
463 config MMU_GATHER_PAGE_SIZE 447 config MMU_GATHER_PAGE_SIZE
464 bool 448 bool
465 449
466 config MMU_GATHER_NO_RANGE 450 config MMU_GATHER_NO_RANGE
467 bool 451 bool
468 select MMU_GATHER_MERGE_VMAS 452 select MMU_GATHER_MERGE_VMAS
469 453
470 config MMU_GATHER_NO_FLUSH_CACHE 454 config MMU_GATHER_NO_FLUSH_CACHE
471 bool 455 bool
472 456
473 config MMU_GATHER_MERGE_VMAS 457 config MMU_GATHER_MERGE_VMAS
474 bool 458 bool
475 459
476 config MMU_GATHER_NO_GATHER 460 config MMU_GATHER_NO_GATHER
477 bool 461 bool
478 depends on MMU_GATHER_TABLE_FREE 462 depends on MMU_GATHER_TABLE_FREE
479 463
480 config ARCH_WANT_IRQS_OFF_ACTIVATE_MM 464 config ARCH_WANT_IRQS_OFF_ACTIVATE_MM
481 bool 465 bool
482 help 466 help
483 Temporary select until all architect 467 Temporary select until all architectures can be converted to have
484 irqs disabled over activate_mm. Arch 468 irqs disabled over activate_mm. Architectures that do IPI based TLB
485 shootdowns should enable this. 469 shootdowns should enable this.
486 470
487 # Use normal mm refcounting for MMU_LAZY_TLB k 471 # Use normal mm refcounting for MMU_LAZY_TLB kernel thread references.
488 # MMU_LAZY_TLB_REFCOUNT=n can improve the scal 472 # MMU_LAZY_TLB_REFCOUNT=n can improve the scalability of context switching
489 # 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
490 # multi-threaded application), by reducing con 474 # multi-threaded application), by reducing contention on the mm refcount.
491 # 475 #
492 # 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
493 # "lazy tlb" beyond its final refcount (i.e., 477 # "lazy tlb" beyond its final refcount (i.e., by the time __mmdrop frees the mm
494 # or its kernel page tables). This could be ar 478 # or its kernel page tables). This could be arranged by arch_exit_mmap(), or
495 # final exit(2) TLB flush, for example. 479 # final exit(2) TLB flush, for example.
496 # 480 #
497 # To implement this, an arch *must*: 481 # To implement this, an arch *must*:
498 # Ensure the _lazy_tlb variants of mmgrab/mmdr 482 # Ensure the _lazy_tlb variants of mmgrab/mmdrop are used when manipulating
499 # 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
500 # converted already). 484 # converted already).
501 config MMU_LAZY_TLB_REFCOUNT 485 config MMU_LAZY_TLB_REFCOUNT
502 def_bool y 486 def_bool y
503 depends on !MMU_LAZY_TLB_SHOOTDOWN 487 depends on !MMU_LAZY_TLB_SHOOTDOWN
504 488
505 # This option allows MMU_LAZY_TLB_REFCOUNT=n. 489 # This option allows MMU_LAZY_TLB_REFCOUNT=n. It ensures no CPUs are using an
506 # 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
507 # users before the mm is deallocated. __mmdrop 491 # users before the mm is deallocated. __mmdrop() first IPIs all CPUs that may
508 # 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
509 # 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
510 # may be using mm as a lazy tlb mm. 494 # may be using mm as a lazy tlb mm.
511 # 495 #
512 # To implement this, an arch *must*: 496 # To implement this, an arch *must*:
513 # - 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
514 # at least all possible CPUs in which the mm 498 # at least all possible CPUs in which the mm is lazy.
515 # - It must meet the requirements for MMU_LAZY 499 # - It must meet the requirements for MMU_LAZY_TLB_REFCOUNT=n (see above).
516 config MMU_LAZY_TLB_SHOOTDOWN 500 config MMU_LAZY_TLB_SHOOTDOWN
517 bool 501 bool
518 502
519 config ARCH_HAVE_NMI_SAFE_CMPXCHG 503 config ARCH_HAVE_NMI_SAFE_CMPXCHG
520 bool 504 bool
521 505
522 config ARCH_HAVE_EXTRA_ELF_NOTES <<
523 bool <<
524 help <<
525 An architecture should select this i <<
526 arch-specific ELF note section to co <<
527 functions: elf_coredump_extra_notes_ <<
528 elf_coredump_extra_notes_write() whi <<
529 dumper. <<
530 <<
531 config ARCH_HAS_NMI_SAFE_THIS_CPU_OPS 506 config ARCH_HAS_NMI_SAFE_THIS_CPU_OPS
532 bool 507 bool
533 508
534 config HAVE_ALIGNED_STRUCT_PAGE 509 config HAVE_ALIGNED_STRUCT_PAGE
535 bool 510 bool
536 help 511 help
537 This makes sure that struct pages ar 512 This makes sure that struct pages are double word aligned and that
538 e.g. the SLUB allocator can perform 513 e.g. the SLUB allocator can perform double word atomic operations
539 on a struct page for better performa 514 on a struct page for better performance. However selecting this
540 might increase the size of a struct 515 might increase the size of a struct page by a word.
541 516
542 config HAVE_CMPXCHG_LOCAL 517 config HAVE_CMPXCHG_LOCAL
543 bool 518 bool
544 519
545 config HAVE_CMPXCHG_DOUBLE 520 config HAVE_CMPXCHG_DOUBLE
546 bool 521 bool
547 522
548 config ARCH_WEAK_RELEASE_ACQUIRE 523 config ARCH_WEAK_RELEASE_ACQUIRE
549 bool 524 bool
550 525
551 config ARCH_WANT_IPC_PARSE_VERSION 526 config ARCH_WANT_IPC_PARSE_VERSION
552 bool 527 bool
553 528
554 config ARCH_WANT_COMPAT_IPC_PARSE_VERSION 529 config ARCH_WANT_COMPAT_IPC_PARSE_VERSION
555 bool 530 bool
556 531
557 config ARCH_WANT_OLD_COMPAT_IPC 532 config ARCH_WANT_OLD_COMPAT_IPC
558 select ARCH_WANT_COMPAT_IPC_PARSE_VERS 533 select ARCH_WANT_COMPAT_IPC_PARSE_VERSION
559 bool 534 bool
560 535
561 config HAVE_ARCH_SECCOMP 536 config HAVE_ARCH_SECCOMP
562 bool 537 bool
563 help 538 help
564 An arch should select this symbol to 539 An arch should select this symbol to support seccomp mode 1 (the fixed
565 syscall policy), and must provide an 540 syscall policy), and must provide an overrides for __NR_seccomp_sigreturn,
566 and compat syscalls if the asm-gener 541 and compat syscalls if the asm-generic/seccomp.h defaults need adjustment:
567 - __NR_seccomp_read_32 542 - __NR_seccomp_read_32
568 - __NR_seccomp_write_32 543 - __NR_seccomp_write_32
569 - __NR_seccomp_exit_32 544 - __NR_seccomp_exit_32
570 - __NR_seccomp_sigreturn_32 545 - __NR_seccomp_sigreturn_32
571 546
572 config HAVE_ARCH_SECCOMP_FILTER 547 config HAVE_ARCH_SECCOMP_FILTER
573 bool 548 bool
574 select HAVE_ARCH_SECCOMP 549 select HAVE_ARCH_SECCOMP
575 help 550 help
576 An arch should select this symbol if 551 An arch should select this symbol if it provides all of these things:
577 - all the requirements for HAVE_ARCH 552 - all the requirements for HAVE_ARCH_SECCOMP
578 - syscall_get_arch() 553 - syscall_get_arch()
579 - syscall_get_arguments() 554 - syscall_get_arguments()
580 - syscall_rollback() 555 - syscall_rollback()
581 - syscall_set_return_value() 556 - syscall_set_return_value()
582 - SIGSYS siginfo_t support 557 - SIGSYS siginfo_t support
583 - secure_computing is called from a 558 - secure_computing is called from a ptrace_event()-safe context
584 - secure_computing return value is c 559 - secure_computing return value is checked and a return value of -1
585 results in the system call being s 560 results in the system call being skipped immediately.
586 - seccomp syscall wired up 561 - seccomp syscall wired up
587 - if !HAVE_SPARSE_SYSCALL_NR, have S 562 - if !HAVE_SPARSE_SYSCALL_NR, have SECCOMP_ARCH_NATIVE,
588 SECCOMP_ARCH_NATIVE_NR, SECCOMP_AR 563 SECCOMP_ARCH_NATIVE_NR, SECCOMP_ARCH_NATIVE_NAME defined. If
589 COMPAT is supported, have the SECC 564 COMPAT is supported, have the SECCOMP_ARCH_COMPAT* defines too.
590 565
591 config SECCOMP 566 config SECCOMP
592 prompt "Enable seccomp to safely execu 567 prompt "Enable seccomp to safely execute untrusted bytecode"
593 def_bool y 568 def_bool y
594 depends on HAVE_ARCH_SECCOMP 569 depends on HAVE_ARCH_SECCOMP
595 help 570 help
596 This kernel feature is useful for nu 571 This kernel feature is useful for number crunching applications
597 that may need to handle untrusted by 572 that may need to handle untrusted bytecode during their
598 execution. By using pipes or other t 573 execution. By using pipes or other transports made available
599 to the process as file descriptors s 574 to the process as file descriptors supporting the read/write
600 syscalls, it's possible to isolate t 575 syscalls, it's possible to isolate those applications in their
601 own address space using seccomp. Onc 576 own address space using seccomp. Once seccomp is enabled via
602 prctl(PR_SET_SECCOMP) or the seccomp 577 prctl(PR_SET_SECCOMP) or the seccomp() syscall, it cannot be
603 disabled and the task is only allowe 578 disabled and the task is only allowed to execute a few safe
604 syscalls defined by each seccomp mod 579 syscalls defined by each seccomp mode.
605 580
606 If unsure, say Y. 581 If unsure, say Y.
607 582
608 config SECCOMP_FILTER 583 config SECCOMP_FILTER
609 def_bool y 584 def_bool y
610 depends on HAVE_ARCH_SECCOMP_FILTER && 585 depends on HAVE_ARCH_SECCOMP_FILTER && SECCOMP && NET
611 help 586 help
612 Enable tasks to build secure computi 587 Enable tasks to build secure computing environments defined
613 in terms of Berkeley Packet Filter p 588 in terms of Berkeley Packet Filter programs which implement
614 task-defined system call filtering p 589 task-defined system call filtering polices.
615 590
616 See Documentation/userspace-api/secc 591 See Documentation/userspace-api/seccomp_filter.rst for details.
617 592
618 config SECCOMP_CACHE_DEBUG 593 config SECCOMP_CACHE_DEBUG
619 bool "Show seccomp filter cache status 594 bool "Show seccomp filter cache status in /proc/pid/seccomp_cache"
620 depends on SECCOMP_FILTER && !HAVE_SPA 595 depends on SECCOMP_FILTER && !HAVE_SPARSE_SYSCALL_NR
621 depends on PROC_FS 596 depends on PROC_FS
622 help 597 help
623 This enables the /proc/pid/seccomp_c 598 This enables the /proc/pid/seccomp_cache interface to monitor
624 seccomp cache data. The file format 599 seccomp cache data. The file format is subject to change. Reading
625 the file requires CAP_SYS_ADMIN. 600 the file requires CAP_SYS_ADMIN.
626 601
627 This option is for debugging only. E 602 This option is for debugging only. Enabling presents the risk that
628 an adversary may be able to infer th 603 an adversary may be able to infer the seccomp filter logic.
629 604
630 If unsure, say N. 605 If unsure, say N.
631 606
632 config HAVE_ARCH_STACKLEAK 607 config HAVE_ARCH_STACKLEAK
633 bool 608 bool
634 help 609 help
635 An architecture should select this i 610 An architecture should select this if it has the code which
636 fills the used part of the kernel st 611 fills the used part of the kernel stack with the STACKLEAK_POISON
637 value before returning from system c 612 value before returning from system calls.
638 613
639 config HAVE_STACKPROTECTOR 614 config HAVE_STACKPROTECTOR
640 bool 615 bool
641 help 616 help
642 An arch should select this symbol if 617 An arch should select this symbol if:
643 - it has implemented a stack canary 618 - it has implemented a stack canary (e.g. __stack_chk_guard)
644 619
645 config STACKPROTECTOR 620 config STACKPROTECTOR
646 bool "Stack Protector buffer overflow 621 bool "Stack Protector buffer overflow detection"
647 depends on HAVE_STACKPROTECTOR 622 depends on HAVE_STACKPROTECTOR
648 depends on $(cc-option,-fstack-protect 623 depends on $(cc-option,-fstack-protector)
649 default y 624 default y
650 help 625 help
651 This option turns on the "stack-prot 626 This option turns on the "stack-protector" GCC feature. This
652 feature puts, at the beginning of fu 627 feature puts, at the beginning of functions, a canary value on
653 the stack just before the return add 628 the stack just before the return address, and validates
654 the value just before actually retur 629 the value just before actually returning. Stack based buffer
655 overflows (that need to overwrite th 630 overflows (that need to overwrite this return address) now also
656 overwrite the canary, which gets det 631 overwrite the canary, which gets detected and the attack is then
657 neutralized via a kernel panic. 632 neutralized via a kernel panic.
658 633
659 Functions will have the stack-protec 634 Functions will have the stack-protector canary logic added if they
660 have an 8-byte or larger character a 635 have an 8-byte or larger character array on the stack.
661 636
662 This feature requires gcc version 4. 637 This feature requires gcc version 4.2 or above, or a distribution
663 gcc with the feature backported ("-f 638 gcc with the feature backported ("-fstack-protector").
664 639
665 On an x86 "defconfig" build, this fe 640 On an x86 "defconfig" build, this feature adds canary checks to
666 about 3% of all kernel functions, wh 641 about 3% of all kernel functions, which increases kernel code size
667 by about 0.3%. 642 by about 0.3%.
668 643
669 config STACKPROTECTOR_STRONG 644 config STACKPROTECTOR_STRONG
670 bool "Strong Stack Protector" 645 bool "Strong Stack Protector"
671 depends on STACKPROTECTOR 646 depends on STACKPROTECTOR
672 depends on $(cc-option,-fstack-protect 647 depends on $(cc-option,-fstack-protector-strong)
673 default y 648 default y
674 help 649 help
675 Functions will have the stack-protec 650 Functions will have the stack-protector canary logic added in any
676 of the following conditions: 651 of the following conditions:
677 652
678 - local variable's address used as p 653 - local variable's address used as part of the right hand side of an
679 assignment or function argument 654 assignment or function argument
680 - local variable is an array (or uni 655 - local variable is an array (or union containing an array),
681 regardless of array type or length 656 regardless of array type or length
682 - uses register local variables 657 - uses register local variables
683 658
684 This feature requires gcc version 4. 659 This feature requires gcc version 4.9 or above, or a distribution
685 gcc with the feature backported ("-f 660 gcc with the feature backported ("-fstack-protector-strong").
686 661
687 On an x86 "defconfig" build, this fe 662 On an x86 "defconfig" build, this feature adds canary checks to
688 about 20% of all kernel functions, w 663 about 20% of all kernel functions, which increases the kernel code
689 size by about 2%. 664 size by about 2%.
690 665
691 config ARCH_SUPPORTS_SHADOW_CALL_STACK 666 config ARCH_SUPPORTS_SHADOW_CALL_STACK
692 bool 667 bool
693 help 668 help
694 An architecture should select this i 669 An architecture should select this if it supports the compiler's
695 Shadow Call Stack and implements run 670 Shadow Call Stack and implements runtime support for shadow stack
696 switching. 671 switching.
697 672
698 config SHADOW_CALL_STACK 673 config SHADOW_CALL_STACK
699 bool "Shadow Call Stack" 674 bool "Shadow Call Stack"
700 depends on ARCH_SUPPORTS_SHADOW_CALL_S 675 depends on ARCH_SUPPORTS_SHADOW_CALL_STACK
701 depends on DYNAMIC_FTRACE_WITH_ARGS || 676 depends on DYNAMIC_FTRACE_WITH_ARGS || DYNAMIC_FTRACE_WITH_REGS || !FUNCTION_GRAPH_TRACER
702 depends on MMU <<
703 help 677 help
704 This option enables the compiler's S 678 This option enables the compiler's Shadow Call Stack, which
705 uses a shadow stack to protect funct 679 uses a shadow stack to protect function return addresses from
706 being overwritten by an attacker. Mo 680 being overwritten by an attacker. More information can be found
707 in the compiler's documentation: 681 in the compiler's documentation:
708 682
709 - Clang: https://clang.llvm.org/docs 683 - Clang: https://clang.llvm.org/docs/ShadowCallStack.html
710 - GCC: https://gcc.gnu.org/onlinedoc 684 - GCC: https://gcc.gnu.org/onlinedocs/gcc/Instrumentation-Options.html#Instrumentation-Options
711 685
712 Note that security guarantees in the 686 Note that security guarantees in the kernel differ from the
713 ones documented for user space. The 687 ones documented for user space. The kernel must store addresses
714 of shadow stacks in memory, which me 688 of shadow stacks in memory, which means an attacker capable of
715 reading and writing arbitrary memory 689 reading and writing arbitrary memory may be able to locate them
716 and hijack control flow by modifying 690 and hijack control flow by modifying the stacks.
717 691
718 config DYNAMIC_SCS 692 config DYNAMIC_SCS
719 bool 693 bool
720 help 694 help
721 Set by the arch code if it relies on 695 Set by the arch code if it relies on code patching to insert the
722 shadow call stack push and pop instr 696 shadow call stack push and pop instructions rather than on the
723 compiler. 697 compiler.
724 698
725 config LTO 699 config LTO
726 bool 700 bool
727 help 701 help
728 Selected if the kernel will be built 702 Selected if the kernel will be built using the compiler's LTO feature.
729 703
730 config LTO_CLANG 704 config LTO_CLANG
731 bool 705 bool
732 select LTO 706 select LTO
733 help 707 help
734 Selected if the kernel will be built 708 Selected if the kernel will be built using Clang's LTO feature.
735 709
736 config ARCH_SUPPORTS_LTO_CLANG 710 config ARCH_SUPPORTS_LTO_CLANG
737 bool 711 bool
738 help 712 help
739 An architecture should select this o 713 An architecture should select this option if it supports:
740 - compiling with Clang, 714 - compiling with Clang,
741 - compiling inline assembly with Cla 715 - compiling inline assembly with Clang's integrated assembler,
742 - and linking with LLD. 716 - and linking with LLD.
743 717
744 config ARCH_SUPPORTS_LTO_CLANG_THIN 718 config ARCH_SUPPORTS_LTO_CLANG_THIN
745 bool 719 bool
746 help 720 help
747 An architecture should select this o 721 An architecture should select this option if it can support Clang's
748 ThinLTO mode. 722 ThinLTO mode.
749 723
750 config HAS_LTO_CLANG 724 config HAS_LTO_CLANG
751 def_bool y 725 def_bool y
752 depends on CC_IS_CLANG && LD_IS_LLD && 726 depends on CC_IS_CLANG && LD_IS_LLD && AS_IS_LLVM
753 depends on $(success,$(NM) --help | he 727 depends on $(success,$(NM) --help | head -n 1 | grep -qi llvm)
754 depends on $(success,$(AR) --help | he 728 depends on $(success,$(AR) --help | head -n 1 | grep -qi llvm)
755 depends on ARCH_SUPPORTS_LTO_CLANG 729 depends on ARCH_SUPPORTS_LTO_CLANG
756 depends on !FTRACE_MCOUNT_USE_RECORDMC 730 depends on !FTRACE_MCOUNT_USE_RECORDMCOUNT
757 # https://github.com/ClangBuiltLinux/l !! 731 depends on !KASAN || KASAN_HW_TAGS
758 depends on (!KASAN || KASAN_HW_TAGS || <<
759 depends on (!KCOV || CLANG_VERSION >= <<
760 depends on !GCOV_KERNEL 732 depends on !GCOV_KERNEL
761 help 733 help
762 The compiler and Kconfig options sup 734 The compiler and Kconfig options support building with Clang's
763 LTO. 735 LTO.
764 736
765 choice 737 choice
766 prompt "Link Time Optimization (LTO)" 738 prompt "Link Time Optimization (LTO)"
767 default LTO_NONE 739 default LTO_NONE
768 help 740 help
769 This option enables Link Time Optimi 741 This option enables Link Time Optimization (LTO), which allows the
770 compiler to optimize binaries global 742 compiler to optimize binaries globally.
771 743
772 If unsure, select LTO_NONE. Note tha 744 If unsure, select LTO_NONE. Note that LTO is very resource-intensive
773 so it's disabled by default. 745 so it's disabled by default.
774 746
775 config LTO_NONE 747 config LTO_NONE
776 bool "None" 748 bool "None"
777 help 749 help
778 Build the kernel normally, without L 750 Build the kernel normally, without Link Time Optimization (LTO).
779 751
780 config LTO_CLANG_FULL 752 config LTO_CLANG_FULL
781 bool "Clang Full LTO (EXPERIMENTAL)" 753 bool "Clang Full LTO (EXPERIMENTAL)"
782 depends on HAS_LTO_CLANG 754 depends on HAS_LTO_CLANG
783 depends on !COMPILE_TEST 755 depends on !COMPILE_TEST
784 select LTO_CLANG 756 select LTO_CLANG
785 help 757 help
786 This option enables Clang's full Lin 758 This option enables Clang's full Link Time Optimization (LTO), which
787 allows the compiler to optimize the 759 allows the compiler to optimize the kernel globally. If you enable
788 this option, the compiler generates 760 this option, the compiler generates LLVM bitcode instead of ELF
789 object files, and the actual compila 761 object files, and the actual compilation from bitcode happens at
790 the LTO link step, which may take se 762 the LTO link step, which may take several minutes depending on the
791 kernel configuration. More informati 763 kernel configuration. More information can be found from LLVM's
792 documentation: 764 documentation:
793 765
794 https://llvm.org/docs/LinkTimeOpti 766 https://llvm.org/docs/LinkTimeOptimization.html
795 767
796 During link time, this option can us 768 During link time, this option can use a large amount of RAM, and
797 may take much longer than the ThinLT 769 may take much longer than the ThinLTO option.
798 770
799 config LTO_CLANG_THIN 771 config LTO_CLANG_THIN
800 bool "Clang ThinLTO (EXPERIMENTAL)" 772 bool "Clang ThinLTO (EXPERIMENTAL)"
801 depends on HAS_LTO_CLANG && ARCH_SUPPO 773 depends on HAS_LTO_CLANG && ARCH_SUPPORTS_LTO_CLANG_THIN
802 select LTO_CLANG 774 select LTO_CLANG
803 help 775 help
804 This option enables Clang's ThinLTO, 776 This option enables Clang's ThinLTO, which allows for parallel
805 optimization and faster incremental 777 optimization and faster incremental compiles compared to the
806 CONFIG_LTO_CLANG_FULL option. More i 778 CONFIG_LTO_CLANG_FULL option. More information can be found
807 from Clang's documentation: 779 from Clang's documentation:
808 780
809 https://clang.llvm.org/docs/ThinLT 781 https://clang.llvm.org/docs/ThinLTO.html
810 782
811 If unsure, say Y. 783 If unsure, say Y.
812 endchoice 784 endchoice
813 785
814 config ARCH_SUPPORTS_CFI_CLANG 786 config ARCH_SUPPORTS_CFI_CLANG
815 bool 787 bool
816 help 788 help
817 An architecture should select this o 789 An architecture should select this option if it can support Clang's
818 Control-Flow Integrity (CFI) checkin 790 Control-Flow Integrity (CFI) checking.
819 791
820 config ARCH_USES_CFI_TRAPS 792 config ARCH_USES_CFI_TRAPS
821 bool 793 bool
822 794
823 config CFI_CLANG 795 config CFI_CLANG
824 bool "Use Clang's Control Flow Integri 796 bool "Use Clang's Control Flow Integrity (CFI)"
825 depends on ARCH_SUPPORTS_CFI_CLANG 797 depends on ARCH_SUPPORTS_CFI_CLANG
826 depends on $(cc-option,-fsanitize=kcfi 798 depends on $(cc-option,-fsanitize=kcfi)
827 help 799 help
828 This option enables Clang's forward- !! 800 This option enables Clang’s forward-edge Control Flow Integrity
829 (CFI) checking, where the compiler i 801 (CFI) checking, where the compiler injects a runtime check to each
830 indirect function call to ensure the 802 indirect function call to ensure the target is a valid function with
831 the correct static type. This restri 803 the correct static type. This restricts possible call targets and
832 makes it more difficult for an attac 804 makes it more difficult for an attacker to exploit bugs that allow
833 the modification of stored function 805 the modification of stored function pointers. More information can be
834 found from Clang's documentation: 806 found from Clang's documentation:
835 807
836 https://clang.llvm.org/docs/Contro 808 https://clang.llvm.org/docs/ControlFlowIntegrity.html
837 809
838 config CFI_ICALL_NORMALIZE_INTEGERS <<
839 bool "Normalize CFI tags for integers" <<
840 depends on CFI_CLANG <<
841 depends on HAVE_CFI_ICALL_NORMALIZE_IN <<
842 help <<
843 This option normalizes the CFI tags <<
844 integer types of the same size and s <<
845 tag. <<
846 <<
847 The option is separate from CONFIG_R <<
848 When working with build systems that <<
849 convenient to be able to turn on thi <<
850 turned on. <<
851 <<
852 This option is necessary for using C <<
853 <<
854 config HAVE_CFI_ICALL_NORMALIZE_INTEGERS_CLANG <<
855 def_bool y <<
856 depends on $(cc-option,-fsanitize=kcfi <<
857 # With GCOV/KASAN we need this fix: ht <<
858 depends on CLANG_VERSION >= 190103 || <<
859 <<
860 config HAVE_CFI_ICALL_NORMALIZE_INTEGERS_RUSTC <<
861 def_bool y <<
862 depends on HAVE_CFI_ICALL_NORMALIZE_IN <<
863 depends on RUSTC_VERSION >= 107900 <<
864 # With GCOV/KASAN we need this fix: ht <<
865 depends on (RUSTC_LLVM_VERSION >= 1901 <<
866 (!GCOV_KERNEL && !KASAN_GENERI <<
867 <<
868 config CFI_PERMISSIVE 810 config CFI_PERMISSIVE
869 bool "Use CFI in permissive mode" 811 bool "Use CFI in permissive mode"
870 depends on CFI_CLANG 812 depends on CFI_CLANG
871 help 813 help
872 When selected, Control Flow Integrit 814 When selected, Control Flow Integrity (CFI) violations result in a
873 warning instead of a kernel panic. T 815 warning instead of a kernel panic. This option should only be used
874 for finding indirect call type misma 816 for finding indirect call type mismatches during development.
875 817
876 If unsure, say N. 818 If unsure, say N.
877 819
878 config HAVE_ARCH_WITHIN_STACK_FRAMES 820 config HAVE_ARCH_WITHIN_STACK_FRAMES
879 bool 821 bool
880 help 822 help
881 An architecture should select this i 823 An architecture should select this if it can walk the kernel stack
882 frames to determine if an object is 824 frames to determine if an object is part of either the arguments
883 or local variables (i.e. that it exc 825 or local variables (i.e. that it excludes saved return addresses,
884 and similar) by implementing an inli 826 and similar) by implementing an inline arch_within_stack_frames(),
885 which is used by CONFIG_HARDENED_USE 827 which is used by CONFIG_HARDENED_USERCOPY.
886 828
887 config HAVE_CONTEXT_TRACKING_USER 829 config HAVE_CONTEXT_TRACKING_USER
888 bool 830 bool
889 help 831 help
890 Provide kernel/user boundaries probe 832 Provide kernel/user boundaries probes necessary for subsystems
891 that need it, such as userspace RCU 833 that need it, such as userspace RCU extended quiescent state.
892 Syscalls need to be wrapped inside u 834 Syscalls need to be wrapped inside user_exit()-user_enter(), either
893 optimized behind static key or throu 835 optimized behind static key or through the slow path using TIF_NOHZ
894 flag. Exceptions handlers must be wr 836 flag. Exceptions handlers must be wrapped as well. Irqs are already
895 protected inside ct_irq_enter/ct_irq 837 protected inside ct_irq_enter/ct_irq_exit() but preemption or signal
896 handling on irq exit still need to b 838 handling on irq exit still need to be protected.
897 839
898 config HAVE_CONTEXT_TRACKING_USER_OFFSTACK 840 config HAVE_CONTEXT_TRACKING_USER_OFFSTACK
899 bool 841 bool
900 help 842 help
901 Architecture neither relies on excep 843 Architecture neither relies on exception_enter()/exception_exit()
902 nor on schedule_user(). Also preempt 844 nor on schedule_user(). Also preempt_schedule_notrace() and
903 preempt_schedule_irq() can't be call 845 preempt_schedule_irq() can't be called in a preemptible section
904 while context tracking is CT_STATE_U !! 846 while context tracking is CONTEXT_USER. This feature reflects a sane
905 entry implementation where the follo 847 entry implementation where the following requirements are met on
906 critical entry code, ie: before user 848 critical entry code, ie: before user_exit() or after user_enter():
907 849
908 - Critical entry code isn't preempti 850 - Critical entry code isn't preemptible (or better yet:
909 not interruptible). 851 not interruptible).
910 - No use of RCU read side critical s 852 - No use of RCU read side critical sections, unless ct_nmi_enter()
911 got called. 853 got called.
912 - No use of instrumentation, unless 854 - No use of instrumentation, unless instrumentation_begin() got
913 called. 855 called.
914 856
915 config HAVE_TIF_NOHZ 857 config HAVE_TIF_NOHZ
916 bool 858 bool
917 help 859 help
918 Arch relies on TIF_NOHZ and syscall 860 Arch relies on TIF_NOHZ and syscall slow path to implement context
919 tracking calls to user_enter()/user_ 861 tracking calls to user_enter()/user_exit().
920 862
921 config HAVE_VIRT_CPU_ACCOUNTING 863 config HAVE_VIRT_CPU_ACCOUNTING
922 bool 864 bool
923 865
924 config HAVE_VIRT_CPU_ACCOUNTING_IDLE 866 config HAVE_VIRT_CPU_ACCOUNTING_IDLE
925 bool 867 bool
926 help 868 help
927 Architecture has its own way to acco 869 Architecture has its own way to account idle CPU time and therefore
928 doesn't implement vtime_account_idle 870 doesn't implement vtime_account_idle().
929 871
930 config ARCH_HAS_SCALED_CPUTIME 872 config ARCH_HAS_SCALED_CPUTIME
931 bool 873 bool
932 874
933 config HAVE_VIRT_CPU_ACCOUNTING_GEN 875 config HAVE_VIRT_CPU_ACCOUNTING_GEN
934 bool 876 bool
935 default y if 64BIT 877 default y if 64BIT
936 help 878 help
937 With VIRT_CPU_ACCOUNTING_GEN, cputim 879 With VIRT_CPU_ACCOUNTING_GEN, cputime_t becomes 64-bit.
938 Before enabling this option, arch co 880 Before enabling this option, arch code must be audited
939 to ensure there are no races in conc 881 to ensure there are no races in concurrent read/write of
940 cputime_t. For example, reading/writ 882 cputime_t. For example, reading/writing 64-bit cputime_t on
941 some 32-bit arches may require multi 883 some 32-bit arches may require multiple accesses, so proper
942 locking is needed to protect against 884 locking is needed to protect against concurrent accesses.
943 885
944 config HAVE_IRQ_TIME_ACCOUNTING 886 config HAVE_IRQ_TIME_ACCOUNTING
945 bool 887 bool
946 help 888 help
947 Archs need to ensure they use a high 889 Archs need to ensure they use a high enough resolution clock to
948 support irq time accounting and then 890 support irq time accounting and then call enable_sched_clock_irqtime().
949 891
950 config HAVE_MOVE_PUD 892 config HAVE_MOVE_PUD
951 bool 893 bool
952 help 894 help
953 Architectures that select this are a 895 Architectures that select this are able to move page tables at the
954 PUD level. If there are only 3 page 896 PUD level. If there are only 3 page table levels, the move effectively
955 happens at the PGD level. 897 happens at the PGD level.
956 898
957 config HAVE_MOVE_PMD 899 config HAVE_MOVE_PMD
958 bool 900 bool
959 help 901 help
960 Archs that select this are able to m 902 Archs that select this are able to move page tables at the PMD level.
961 903
962 config HAVE_ARCH_TRANSPARENT_HUGEPAGE 904 config HAVE_ARCH_TRANSPARENT_HUGEPAGE
963 bool 905 bool
964 906
965 config HAVE_ARCH_TRANSPARENT_HUGEPAGE_PUD 907 config HAVE_ARCH_TRANSPARENT_HUGEPAGE_PUD
966 bool 908 bool
967 909
968 config HAVE_ARCH_HUGE_VMAP 910 config HAVE_ARCH_HUGE_VMAP
969 bool 911 bool
970 912
971 # 913 #
972 # Archs that select this would be capable of 914 # Archs that select this would be capable of PMD-sized vmaps (i.e.,
973 # arch_vmap_pmd_supported() returns true). Th 915 # arch_vmap_pmd_supported() returns true). The VM_ALLOW_HUGE_VMAP flag
974 # must be used to enable allocations to use h 916 # must be used to enable allocations to use hugepages.
975 # 917 #
976 config HAVE_ARCH_HUGE_VMALLOC 918 config HAVE_ARCH_HUGE_VMALLOC
977 depends on HAVE_ARCH_HUGE_VMAP 919 depends on HAVE_ARCH_HUGE_VMAP
978 bool 920 bool
979 921
980 config ARCH_WANT_HUGE_PMD_SHARE 922 config ARCH_WANT_HUGE_PMD_SHARE
981 bool 923 bool
982 924
983 # Archs that want to use pmd_mkwrite on kernel <<
984 # if there are no userspace memory management <<
985 config ARCH_WANT_KERNEL_PMD_MKWRITE <<
986 bool <<
987 <<
988 config ARCH_WANT_PMD_MKWRITE <<
989 def_bool TRANSPARENT_HUGEPAGE || ARCH_ <<
990 <<
991 config HAVE_ARCH_SOFT_DIRTY 925 config HAVE_ARCH_SOFT_DIRTY
992 bool 926 bool
993 927
994 config HAVE_MOD_ARCH_SPECIFIC 928 config HAVE_MOD_ARCH_SPECIFIC
995 bool 929 bool
996 help 930 help
997 The arch uses struct mod_arch_specif 931 The arch uses struct mod_arch_specific to store data. Many arches
998 just need a simple module loader wit 932 just need a simple module loader without arch specific data - those
999 should not enable this. 933 should not enable this.
1000 934
1001 config MODULES_USE_ELF_RELA 935 config MODULES_USE_ELF_RELA
1002 bool 936 bool
1003 help 937 help
1004 Modules only use ELF RELA relocatio 938 Modules only use ELF RELA relocations. Modules with ELF REL
1005 relocations will give an error. 939 relocations will give an error.
1006 940
1007 config MODULES_USE_ELF_REL 941 config MODULES_USE_ELF_REL
1008 bool 942 bool
1009 help 943 help
1010 Modules only use ELF REL relocation 944 Modules only use ELF REL relocations. Modules with ELF RELA
1011 relocations will give an error. 945 relocations will give an error.
1012 946
1013 config ARCH_WANTS_MODULES_DATA_IN_VMALLOC 947 config ARCH_WANTS_MODULES_DATA_IN_VMALLOC
1014 bool 948 bool
1015 help 949 help
1016 For architectures like powerpc/32 w 950 For architectures like powerpc/32 which have constraints on module
1017 allocation and need to allocate mod 951 allocation and need to allocate module data outside of module area.
1018 952
1019 config ARCH_WANTS_EXECMEM_LATE <<
1020 bool <<
1021 help <<
1022 For architectures that do not alloc <<
1023 boot, but rather require its initia <<
1024 enough entropy for module space ran <<
1025 arm64. <<
1026 <<
1027 config HAVE_IRQ_EXIT_ON_IRQ_STACK 953 config HAVE_IRQ_EXIT_ON_IRQ_STACK
1028 bool 954 bool
1029 help 955 help
1030 Architecture doesn't only execute t 956 Architecture doesn't only execute the irq handler on the irq stack
1031 but also irq_exit(). This way we ca 957 but also irq_exit(). This way we can process softirqs on this irq
1032 stack instead of switching to a new 958 stack instead of switching to a new one when we call __do_softirq()
1033 in the end of an hardirq. 959 in the end of an hardirq.
1034 This spares a stack switch and impr 960 This spares a stack switch and improves cache usage on softirq
1035 processing. 961 processing.
1036 962
1037 config HAVE_SOFTIRQ_ON_OWN_STACK 963 config HAVE_SOFTIRQ_ON_OWN_STACK
1038 bool 964 bool
1039 help 965 help
1040 Architecture provides a function to 966 Architecture provides a function to run __do_softirq() on a
1041 separate stack. 967 separate stack.
1042 968
1043 config SOFTIRQ_ON_OWN_STACK 969 config SOFTIRQ_ON_OWN_STACK
1044 def_bool HAVE_SOFTIRQ_ON_OWN_STACK && 970 def_bool HAVE_SOFTIRQ_ON_OWN_STACK && !PREEMPT_RT
1045 971
1046 config ALTERNATE_USER_ADDRESS_SPACE 972 config ALTERNATE_USER_ADDRESS_SPACE
1047 bool 973 bool
1048 help 974 help
1049 Architectures set this when the CPU 975 Architectures set this when the CPU uses separate address
1050 spaces for kernel and user space po 976 spaces for kernel and user space pointers. In this case, the
1051 access_ok() check on a __user point 977 access_ok() check on a __user pointer is skipped.
1052 978
1053 config PGTABLE_LEVELS 979 config PGTABLE_LEVELS
1054 int 980 int
1055 default 2 981 default 2
1056 982
1057 config ARCH_HAS_ELF_RANDOMIZE 983 config ARCH_HAS_ELF_RANDOMIZE
1058 bool 984 bool
1059 help 985 help
1060 An architecture supports choosing r 986 An architecture supports choosing randomized locations for
1061 stack, mmap, brk, and ET_DYN. Defin 987 stack, mmap, brk, and ET_DYN. Defined functions:
1062 - arch_mmap_rnd() 988 - arch_mmap_rnd()
1063 - arch_randomize_brk() 989 - arch_randomize_brk()
1064 990
1065 config HAVE_ARCH_MMAP_RND_BITS 991 config HAVE_ARCH_MMAP_RND_BITS
1066 bool 992 bool
1067 help 993 help
1068 An arch should select this symbol i 994 An arch should select this symbol if it supports setting a variable
1069 number of bits for use in establish 995 number of bits for use in establishing the base address for mmap
1070 allocations, has MMU enabled and pr 996 allocations, has MMU enabled and provides values for both:
1071 - ARCH_MMAP_RND_BITS_MIN 997 - ARCH_MMAP_RND_BITS_MIN
1072 - ARCH_MMAP_RND_BITS_MAX 998 - ARCH_MMAP_RND_BITS_MAX
1073 999
1074 config HAVE_EXIT_THREAD 1000 config HAVE_EXIT_THREAD
1075 bool 1001 bool
1076 help 1002 help
1077 An architecture implements exit_thr 1003 An architecture implements exit_thread.
1078 1004
1079 config ARCH_MMAP_RND_BITS_MIN 1005 config ARCH_MMAP_RND_BITS_MIN
1080 int 1006 int
1081 1007
1082 config ARCH_MMAP_RND_BITS_MAX 1008 config ARCH_MMAP_RND_BITS_MAX
1083 int 1009 int
1084 1010
1085 config ARCH_MMAP_RND_BITS_DEFAULT 1011 config ARCH_MMAP_RND_BITS_DEFAULT
1086 int 1012 int
1087 1013
1088 config ARCH_MMAP_RND_BITS 1014 config ARCH_MMAP_RND_BITS
1089 int "Number of bits to use for ASLR o 1015 int "Number of bits to use for ASLR of mmap base address" if EXPERT
1090 range ARCH_MMAP_RND_BITS_MIN ARCH_MMA 1016 range ARCH_MMAP_RND_BITS_MIN ARCH_MMAP_RND_BITS_MAX
1091 default ARCH_MMAP_RND_BITS_DEFAULT if 1017 default ARCH_MMAP_RND_BITS_DEFAULT if ARCH_MMAP_RND_BITS_DEFAULT
1092 default ARCH_MMAP_RND_BITS_MIN 1018 default ARCH_MMAP_RND_BITS_MIN
1093 depends on HAVE_ARCH_MMAP_RND_BITS 1019 depends on HAVE_ARCH_MMAP_RND_BITS
1094 help 1020 help
1095 This value can be used to select th 1021 This value can be used to select the number of bits to use to
1096 determine the random offset to the 1022 determine the random offset to the base address of vma regions
1097 resulting from mmap allocations. Th 1023 resulting from mmap allocations. This value will be bounded
1098 by the architecture's minimum and m 1024 by the architecture's minimum and maximum supported values.
1099 1025
1100 This value can be changed after boo 1026 This value can be changed after boot using the
1101 /proc/sys/vm/mmap_rnd_bits tunable 1027 /proc/sys/vm/mmap_rnd_bits tunable
1102 1028
1103 config HAVE_ARCH_MMAP_RND_COMPAT_BITS 1029 config HAVE_ARCH_MMAP_RND_COMPAT_BITS
1104 bool 1030 bool
1105 help 1031 help
1106 An arch should select this symbol i 1032 An arch should select this symbol if it supports running applications
1107 in compatibility mode, supports set 1033 in compatibility mode, supports setting a variable number of bits for
1108 use in establishing the base addres 1034 use in establishing the base address for mmap allocations, has MMU
1109 enabled and provides values for bot 1035 enabled and provides values for both:
1110 - ARCH_MMAP_RND_COMPAT_BITS_MIN 1036 - ARCH_MMAP_RND_COMPAT_BITS_MIN
1111 - ARCH_MMAP_RND_COMPAT_BITS_MAX 1037 - ARCH_MMAP_RND_COMPAT_BITS_MAX
1112 1038
1113 config ARCH_MMAP_RND_COMPAT_BITS_MIN 1039 config ARCH_MMAP_RND_COMPAT_BITS_MIN
1114 int 1040 int
1115 1041
1116 config ARCH_MMAP_RND_COMPAT_BITS_MAX 1042 config ARCH_MMAP_RND_COMPAT_BITS_MAX
1117 int 1043 int
1118 1044
1119 config ARCH_MMAP_RND_COMPAT_BITS_DEFAULT 1045 config ARCH_MMAP_RND_COMPAT_BITS_DEFAULT
1120 int 1046 int
1121 1047
1122 config ARCH_MMAP_RND_COMPAT_BITS 1048 config ARCH_MMAP_RND_COMPAT_BITS
1123 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
1124 range ARCH_MMAP_RND_COMPAT_BITS_MIN A 1050 range ARCH_MMAP_RND_COMPAT_BITS_MIN ARCH_MMAP_RND_COMPAT_BITS_MAX
1125 default ARCH_MMAP_RND_COMPAT_BITS_DEF 1051 default ARCH_MMAP_RND_COMPAT_BITS_DEFAULT if ARCH_MMAP_RND_COMPAT_BITS_DEFAULT
1126 default ARCH_MMAP_RND_COMPAT_BITS_MIN 1052 default ARCH_MMAP_RND_COMPAT_BITS_MIN
1127 depends on HAVE_ARCH_MMAP_RND_COMPAT_ 1053 depends on HAVE_ARCH_MMAP_RND_COMPAT_BITS
1128 help 1054 help
1129 This value can be used to select th 1055 This value can be used to select the number of bits to use to
1130 determine the random offset to the 1056 determine the random offset to the base address of vma regions
1131 resulting from mmap allocations for 1057 resulting from mmap allocations for compatible applications This
1132 value will be bounded by the archit 1058 value will be bounded by the architecture's minimum and maximum
1133 supported values. 1059 supported values.
1134 1060
1135 This value can be changed after boo 1061 This value can be changed after boot using the
1136 /proc/sys/vm/mmap_rnd_compat_bits t 1062 /proc/sys/vm/mmap_rnd_compat_bits tunable
1137 1063
1138 config HAVE_ARCH_COMPAT_MMAP_BASES 1064 config HAVE_ARCH_COMPAT_MMAP_BASES
1139 bool 1065 bool
1140 help 1066 help
1141 This allows 64bit applications to i 1067 This allows 64bit applications to invoke 32-bit mmap() syscall
1142 and vice-versa 32-bit applications 1068 and vice-versa 32-bit applications to call 64-bit mmap().
1143 Required for applications doing dif 1069 Required for applications doing different bitness syscalls.
1144 1070
1145 config HAVE_PAGE_SIZE_4KB <<
1146 bool <<
1147 <<
1148 config HAVE_PAGE_SIZE_8KB <<
1149 bool <<
1150 <<
1151 config HAVE_PAGE_SIZE_16KB <<
1152 bool <<
1153 <<
1154 config HAVE_PAGE_SIZE_32KB <<
1155 bool <<
1156 <<
1157 config HAVE_PAGE_SIZE_64KB <<
1158 bool <<
1159 <<
1160 config HAVE_PAGE_SIZE_256KB <<
1161 bool <<
1162 <<
1163 choice <<
1164 prompt "MMU page size" <<
1165 <<
1166 config PAGE_SIZE_4KB <<
1167 bool "4KiB pages" <<
1168 depends on HAVE_PAGE_SIZE_4KB <<
1169 help <<
1170 This option select the standard 4Ki <<
1171 available option on many architectu <<
1172 minimize memory consumption and is <<
1173 memory systems. <<
1174 Some software that is written for x <<
1175 assumptions about the page size and <<
1176 <<
1177 config PAGE_SIZE_8KB <<
1178 bool "8KiB pages" <<
1179 depends on HAVE_PAGE_SIZE_8KB <<
1180 help <<
1181 This option is the only supported p <<
1182 processors, and can be slightly fas <<
1183 <<
1184 config PAGE_SIZE_16KB <<
1185 bool "16KiB pages" <<
1186 depends on HAVE_PAGE_SIZE_16KB <<
1187 help <<
1188 This option is usually a good compr <<
1189 consumption and performance for typ <<
1190 workloads, often saving a level of <<
1191 to 4KB pages as well as reducing TL <<
1192 per-page operations in the kernel a <<
1193 page cache. <<
1194 <<
1195 config PAGE_SIZE_32KB <<
1196 bool "32KiB pages" <<
1197 depends on HAVE_PAGE_SIZE_32KB <<
1198 help <<
1199 Using 32KiB page size will result i <<
1200 kernel at the price of higher memor <<
1201 16KiB pages. This option is availa <<
1202 Note that you will need a suitable <<
1203 support this. <<
1204 <<
1205 config PAGE_SIZE_64KB <<
1206 bool "64KiB pages" <<
1207 depends on HAVE_PAGE_SIZE_64KB <<
1208 help <<
1209 Using 64KiB page size will result i <<
1210 kernel at the price of much higher <<
1211 4KiB or 16KiB pages. <<
1212 This is not suitable for general-pu <<
1213 better performance may be worth the <<
1214 supercomputing or database applicat <<
1215 large in-memory data rather than sm <<
1216 <<
1217 config PAGE_SIZE_256KB <<
1218 bool "256KiB pages" <<
1219 depends on HAVE_PAGE_SIZE_256KB <<
1220 help <<
1221 256KiB pages have little practical <<
1222 memory usage. The kernel will only <<
1223 that have been compiled with '-zmax <<
1224 (the default is 64KiB or 4KiB on mo <<
1225 <<
1226 endchoice <<
1227 <<
1228 config PAGE_SIZE_LESS_THAN_64KB 1071 config PAGE_SIZE_LESS_THAN_64KB
1229 def_bool y 1072 def_bool y
>> 1073 depends on !ARM64_64K_PAGES
>> 1074 depends on !IA64_PAGE_SIZE_64KB
1230 depends on !PAGE_SIZE_64KB 1075 depends on !PAGE_SIZE_64KB
>> 1076 depends on !PARISC_PAGE_SIZE_64KB
1231 depends on PAGE_SIZE_LESS_THAN_256KB 1077 depends on PAGE_SIZE_LESS_THAN_256KB
1232 1078
1233 config PAGE_SIZE_LESS_THAN_256KB 1079 config PAGE_SIZE_LESS_THAN_256KB
1234 def_bool y 1080 def_bool y
1235 depends on !PAGE_SIZE_256KB 1081 depends on !PAGE_SIZE_256KB
1236 1082
1237 config PAGE_SHIFT <<
1238 int <<
1239 default 12 if PAGE_SIZE_4KB <<
1240 default 13 if PAGE_SIZE_8KB <<
1241 default 14 if PAGE_SIZE_16KB <<
1242 default 15 if PAGE_SIZE_32KB <<
1243 default 16 if PAGE_SIZE_64KB <<
1244 default 18 if PAGE_SIZE_256KB <<
1245 <<
1246 # This allows to use a set of generic functio 1083 # This allows to use a set of generic functions to determine mmap base
1247 # address by giving priority to top-down sche 1084 # address by giving priority to top-down scheme only if the process
1248 # is not in legacy mode (compat task, unlimit 1085 # is not in legacy mode (compat task, unlimited stack size or
1249 # sysctl_legacy_va_layout). 1086 # sysctl_legacy_va_layout).
1250 # Architecture that selects this option can p 1087 # Architecture that selects this option can provide its own version of:
1251 # - STACK_RND_MASK 1088 # - STACK_RND_MASK
1252 config ARCH_WANT_DEFAULT_TOPDOWN_MMAP_LAYOUT 1089 config ARCH_WANT_DEFAULT_TOPDOWN_MMAP_LAYOUT
1253 bool 1090 bool
1254 depends on MMU 1091 depends on MMU
1255 select ARCH_HAS_ELF_RANDOMIZE 1092 select ARCH_HAS_ELF_RANDOMIZE
1256 1093
1257 config HAVE_OBJTOOL 1094 config HAVE_OBJTOOL
1258 bool 1095 bool
1259 1096
1260 config HAVE_JUMP_LABEL_HACK 1097 config HAVE_JUMP_LABEL_HACK
1261 bool 1098 bool
1262 1099
1263 config HAVE_NOINSTR_HACK 1100 config HAVE_NOINSTR_HACK
1264 bool 1101 bool
1265 1102
1266 config HAVE_NOINSTR_VALIDATION 1103 config HAVE_NOINSTR_VALIDATION
1267 bool 1104 bool
1268 1105
1269 config HAVE_UACCESS_VALIDATION 1106 config HAVE_UACCESS_VALIDATION
1270 bool 1107 bool
1271 select OBJTOOL 1108 select OBJTOOL
1272 1109
1273 config HAVE_STACK_VALIDATION 1110 config HAVE_STACK_VALIDATION
1274 bool 1111 bool
1275 help 1112 help
1276 Architecture supports objtool compi 1113 Architecture supports objtool compile-time frame pointer rule
1277 validation. 1114 validation.
1278 1115
1279 config HAVE_RELIABLE_STACKTRACE 1116 config HAVE_RELIABLE_STACKTRACE
1280 bool 1117 bool
1281 help 1118 help
1282 Architecture has either save_stack_ 1119 Architecture has either save_stack_trace_tsk_reliable() or
1283 arch_stack_walk_reliable() function 1120 arch_stack_walk_reliable() function which only returns a stack trace
1284 if it can guarantee the trace is re 1121 if it can guarantee the trace is reliable.
1285 1122
1286 config HAVE_ARCH_HASH 1123 config HAVE_ARCH_HASH
1287 bool 1124 bool
1288 default n 1125 default n
1289 help 1126 help
1290 If this is set, the architecture pr 1127 If this is set, the architecture provides an <asm/hash.h>
1291 file which provides platform-specif 1128 file which provides platform-specific implementations of some
1292 functions in <linux/hash.h> or fs/n 1129 functions in <linux/hash.h> or fs/namei.c.
1293 1130
1294 config HAVE_ARCH_NVRAM_OPS 1131 config HAVE_ARCH_NVRAM_OPS
1295 bool 1132 bool
1296 1133
1297 config ISA_BUS_API 1134 config ISA_BUS_API
1298 def_bool ISA 1135 def_bool ISA
1299 1136
1300 # 1137 #
1301 # ABI hall of shame 1138 # ABI hall of shame
1302 # 1139 #
1303 config CLONE_BACKWARDS 1140 config CLONE_BACKWARDS
1304 bool 1141 bool
1305 help 1142 help
1306 Architecture has tls passed as the 1143 Architecture has tls passed as the 4th argument of clone(2),
1307 not the 5th one. 1144 not the 5th one.
1308 1145
1309 config CLONE_BACKWARDS2 1146 config CLONE_BACKWARDS2
1310 bool 1147 bool
1311 help 1148 help
1312 Architecture has the first two argu 1149 Architecture has the first two arguments of clone(2) swapped.
1313 1150
1314 config CLONE_BACKWARDS3 1151 config CLONE_BACKWARDS3
1315 bool 1152 bool
1316 help 1153 help
1317 Architecture has tls passed as the 1154 Architecture has tls passed as the 3rd argument of clone(2),
1318 not the 5th one. 1155 not the 5th one.
1319 1156
1320 config ODD_RT_SIGACTION 1157 config ODD_RT_SIGACTION
1321 bool 1158 bool
1322 help 1159 help
1323 Architecture has unusual rt_sigacti 1160 Architecture has unusual rt_sigaction(2) arguments
1324 1161
1325 config OLD_SIGSUSPEND 1162 config OLD_SIGSUSPEND
1326 bool 1163 bool
1327 help 1164 help
1328 Architecture has old sigsuspend(2) 1165 Architecture has old sigsuspend(2) syscall, of one-argument variety
1329 1166
1330 config OLD_SIGSUSPEND3 1167 config OLD_SIGSUSPEND3
1331 bool 1168 bool
1332 help 1169 help
1333 Even weirder antique ABI - three-ar 1170 Even weirder antique ABI - three-argument sigsuspend(2)
1334 1171
1335 config OLD_SIGACTION 1172 config OLD_SIGACTION
1336 bool 1173 bool
1337 help 1174 help
1338 Architecture has old sigaction(2) s 1175 Architecture has old sigaction(2) syscall. Nope, not the same
1339 as OLD_SIGSUSPEND | OLD_SIGSUSPEND3 1176 as OLD_SIGSUSPEND | OLD_SIGSUSPEND3 - alpha has sigsuspend(2),
1340 but fairly different variant of sig 1177 but fairly different variant of sigaction(2), thanks to OSF/1
1341 compatibility... 1178 compatibility...
1342 1179
1343 config COMPAT_OLD_SIGACTION 1180 config COMPAT_OLD_SIGACTION
1344 bool 1181 bool
1345 1182
1346 config COMPAT_32BIT_TIME 1183 config COMPAT_32BIT_TIME
1347 bool "Provide system calls for 32-bit 1184 bool "Provide system calls for 32-bit time_t"
1348 default !64BIT || COMPAT 1185 default !64BIT || COMPAT
1349 help 1186 help
1350 This enables 32 bit time_t support 1187 This enables 32 bit time_t support in addition to 64 bit time_t support.
1351 This is relevant on all 32-bit arch 1188 This is relevant on all 32-bit architectures, and 64-bit architectures
1352 as part of compat syscall handling. 1189 as part of compat syscall handling.
1353 1190
1354 config ARCH_NO_PREEMPT 1191 config ARCH_NO_PREEMPT
1355 bool 1192 bool
1356 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
1357 config ARCH_SUPPORTS_RT 1201 config ARCH_SUPPORTS_RT
1358 bool 1202 bool
1359 1203
1360 config CPU_NO_EFFICIENT_FFS 1204 config CPU_NO_EFFICIENT_FFS
1361 def_bool n 1205 def_bool n
1362 1206
1363 config HAVE_ARCH_VMAP_STACK 1207 config HAVE_ARCH_VMAP_STACK
1364 def_bool n 1208 def_bool n
1365 help 1209 help
1366 An arch should select this symbol i 1210 An arch should select this symbol if it can support kernel stacks
1367 in vmalloc space. This means: 1211 in vmalloc space. This means:
1368 1212
1369 - vmalloc space must be large enoug 1213 - vmalloc space must be large enough to hold many kernel stacks.
1370 This may rule out many 32-bit arc 1214 This may rule out many 32-bit architectures.
1371 1215
1372 - Stacks in vmalloc space need to w 1216 - Stacks in vmalloc space need to work reliably. For example, if
1373 vmap page tables are created on d 1217 vmap page tables are created on demand, either this mechanism
1374 needs to work while the stack poi 1218 needs to work while the stack points to a virtual address with
1375 unpopulated page tables or arch c 1219 unpopulated page tables or arch code (switch_to() and switch_mm(),
1376 most likely) needs to ensure that 1220 most likely) needs to ensure that the stack's page table entries
1377 are populated before running on a 1221 are populated before running on a possibly unpopulated stack.
1378 1222
1379 - If the stack overflows into a gua 1223 - If the stack overflows into a guard page, something reasonable
1380 should happen. The definition of 1224 should happen. The definition of "reasonable" is flexible, but
1381 instantly rebooting without loggi 1225 instantly rebooting without logging anything would be unfriendly.
1382 1226
1383 config VMAP_STACK 1227 config VMAP_STACK
1384 default y 1228 default y
1385 bool "Use a virtually-mapped stack" 1229 bool "Use a virtually-mapped stack"
1386 depends on HAVE_ARCH_VMAP_STACK 1230 depends on HAVE_ARCH_VMAP_STACK
1387 depends on !KASAN || KASAN_HW_TAGS || 1231 depends on !KASAN || KASAN_HW_TAGS || KASAN_VMALLOC
1388 help 1232 help
1389 Enable this if you want the use vir 1233 Enable this if you want the use virtually-mapped kernel stacks
1390 with guard pages. This causes kern 1234 with guard pages. This causes kernel stack overflows to be
1391 caught immediately rather than caus 1235 caught immediately rather than causing difficult-to-diagnose
1392 corruption. 1236 corruption.
1393 1237
1394 To use this with software KASAN mod 1238 To use this with software KASAN modes, the architecture must support
1395 backing virtual mappings with real 1239 backing virtual mappings with real shadow memory, and KASAN_VMALLOC
1396 must be enabled. 1240 must be enabled.
1397 1241
1398 config HAVE_ARCH_RANDOMIZE_KSTACK_OFFSET 1242 config HAVE_ARCH_RANDOMIZE_KSTACK_OFFSET
1399 def_bool n 1243 def_bool n
1400 help 1244 help
1401 An arch should select this symbol i 1245 An arch should select this symbol if it can support kernel stack
1402 offset randomization with calls to 1246 offset randomization with calls to add_random_kstack_offset()
1403 during syscall entry and choose_ran 1247 during syscall entry and choose_random_kstack_offset() during
1404 syscall exit. Careful removal of -f 1248 syscall exit. Careful removal of -fstack-protector-strong and
1405 -fstack-protector should also be ap 1249 -fstack-protector should also be applied to the entry code and
1406 closely examined, as the artificial 1250 closely examined, as the artificial stack bump looks like an array
1407 to the compiler, so it will attempt 1251 to the compiler, so it will attempt to add canary checks regardless
1408 of the static branch state. 1252 of the static branch state.
1409 1253
1410 config RANDOMIZE_KSTACK_OFFSET 1254 config RANDOMIZE_KSTACK_OFFSET
1411 bool "Support for randomizing kernel 1255 bool "Support for randomizing kernel stack offset on syscall entry" if EXPERT
1412 default y 1256 default y
1413 depends on HAVE_ARCH_RANDOMIZE_KSTACK 1257 depends on HAVE_ARCH_RANDOMIZE_KSTACK_OFFSET
1414 depends on INIT_STACK_NONE || !CC_IS_ 1258 depends on INIT_STACK_NONE || !CC_IS_CLANG || CLANG_VERSION >= 140000
1415 help 1259 help
1416 The kernel stack offset can be rand 1260 The kernel stack offset can be randomized (after pt_regs) by
1417 roughly 5 bits of entropy, frustrat 1261 roughly 5 bits of entropy, frustrating memory corruption
1418 attacks that depend on stack addres 1262 attacks that depend on stack address determinism or
1419 cross-syscall address exposures. 1263 cross-syscall address exposures.
1420 1264
1421 The feature is controlled via the " 1265 The feature is controlled via the "randomize_kstack_offset=on/off"
1422 kernel boot param, and if turned of 1266 kernel boot param, and if turned off has zero overhead due to its use
1423 of static branches (see JUMP_LABEL) 1267 of static branches (see JUMP_LABEL).
1424 1268
1425 If unsure, say Y. 1269 If unsure, say Y.
1426 1270
1427 config RANDOMIZE_KSTACK_OFFSET_DEFAULT 1271 config RANDOMIZE_KSTACK_OFFSET_DEFAULT
1428 bool "Default state of kernel stack o 1272 bool "Default state of kernel stack offset randomization"
1429 depends on RANDOMIZE_KSTACK_OFFSET 1273 depends on RANDOMIZE_KSTACK_OFFSET
1430 help 1274 help
1431 Kernel stack offset randomization i 1275 Kernel stack offset randomization is controlled by kernel boot param
1432 "randomize_kstack_offset=on/off", a 1276 "randomize_kstack_offset=on/off", and this config chooses the default
1433 boot state. 1277 boot state.
1434 1278
1435 config ARCH_OPTIONAL_KERNEL_RWX 1279 config ARCH_OPTIONAL_KERNEL_RWX
1436 def_bool n 1280 def_bool n
1437 1281
1438 config ARCH_OPTIONAL_KERNEL_RWX_DEFAULT 1282 config ARCH_OPTIONAL_KERNEL_RWX_DEFAULT
1439 def_bool n 1283 def_bool n
1440 1284
1441 config ARCH_HAS_STRICT_KERNEL_RWX 1285 config ARCH_HAS_STRICT_KERNEL_RWX
1442 def_bool n 1286 def_bool n
1443 1287
1444 config STRICT_KERNEL_RWX 1288 config STRICT_KERNEL_RWX
1445 bool "Make kernel text and rodata rea 1289 bool "Make kernel text and rodata read-only" if ARCH_OPTIONAL_KERNEL_RWX
1446 depends on ARCH_HAS_STRICT_KERNEL_RWX 1290 depends on ARCH_HAS_STRICT_KERNEL_RWX
1447 default !ARCH_OPTIONAL_KERNEL_RWX || 1291 default !ARCH_OPTIONAL_KERNEL_RWX || ARCH_OPTIONAL_KERNEL_RWX_DEFAULT
1448 help 1292 help
1449 If this is set, kernel text and rod 1293 If this is set, kernel text and rodata memory will be made read-only,
1450 and non-text memory will be made no 1294 and non-text memory will be made non-executable. This provides
1451 protection against certain security 1295 protection against certain security exploits (e.g. executing the heap
1452 or modifying text) 1296 or modifying text)
1453 1297
1454 These features are considered stand 1298 These features are considered standard security practice these days.
1455 You should say Y here in almost all 1299 You should say Y here in almost all cases.
1456 1300
1457 config ARCH_HAS_STRICT_MODULE_RWX 1301 config ARCH_HAS_STRICT_MODULE_RWX
1458 def_bool n 1302 def_bool n
1459 1303
1460 config STRICT_MODULE_RWX 1304 config STRICT_MODULE_RWX
1461 bool "Set loadable kernel module data 1305 bool "Set loadable kernel module data as NX and text as RO" if ARCH_OPTIONAL_KERNEL_RWX
1462 depends on ARCH_HAS_STRICT_MODULE_RWX 1306 depends on ARCH_HAS_STRICT_MODULE_RWX && MODULES
1463 default !ARCH_OPTIONAL_KERNEL_RWX || 1307 default !ARCH_OPTIONAL_KERNEL_RWX || ARCH_OPTIONAL_KERNEL_RWX_DEFAULT
1464 help 1308 help
1465 If this is set, module text and rod 1309 If this is set, module text and rodata memory will be made read-only,
1466 and non-text memory will be made no 1310 and non-text memory will be made non-executable. This provides
1467 protection against certain security 1311 protection against certain security exploits (e.g. writing to text)
1468 1312
1469 # select if the architecture provides an asm/ 1313 # select if the architecture provides an asm/dma-direct.h header
1470 config ARCH_HAS_PHYS_TO_DMA 1314 config ARCH_HAS_PHYS_TO_DMA
1471 bool 1315 bool
1472 1316
1473 config HAVE_ARCH_COMPILER_H 1317 config HAVE_ARCH_COMPILER_H
1474 bool 1318 bool
1475 help 1319 help
1476 An architecture can select this if 1320 An architecture can select this if it provides an
1477 asm/compiler.h header that should b 1321 asm/compiler.h header that should be included after
1478 linux/compiler-*.h in order to over 1322 linux/compiler-*.h in order to override macro definitions that those
1479 headers generally provide. 1323 headers generally provide.
1480 1324
1481 config HAVE_ARCH_PREL32_RELOCATIONS 1325 config HAVE_ARCH_PREL32_RELOCATIONS
1482 bool 1326 bool
1483 help 1327 help
1484 May be selected by an architecture 1328 May be selected by an architecture if it supports place-relative
1485 32-bit relocations, both in the too 1329 32-bit relocations, both in the toolchain and in the module loader,
1486 in which case relative references c 1330 in which case relative references can be used in special sections
1487 for PCI fixup, initcalls etc which 1331 for PCI fixup, initcalls etc which are only half the size on 64 bit
1488 architectures, and don't require ru 1332 architectures, and don't require runtime relocation on relocatable
1489 kernels. 1333 kernels.
1490 1334
1491 config ARCH_USE_MEMREMAP_PROT 1335 config ARCH_USE_MEMREMAP_PROT
1492 bool 1336 bool
1493 1337
1494 config LOCK_EVENT_COUNTS 1338 config LOCK_EVENT_COUNTS
1495 bool "Locking event counts collection 1339 bool "Locking event counts collection"
1496 depends on DEBUG_FS 1340 depends on DEBUG_FS
1497 help 1341 help
1498 Enable light-weight counting of var 1342 Enable light-weight counting of various locking related events
1499 in the system with minimal performa 1343 in the system with minimal performance impact. This reduces
1500 the chance of application behavior 1344 the chance of application behavior change because of timing
1501 differences. The counts are reporte 1345 differences. The counts are reported via debugfs.
1502 1346
1503 # Select if the architecture has support for 1347 # Select if the architecture has support for applying RELR relocations.
1504 config ARCH_HAS_RELR 1348 config ARCH_HAS_RELR
1505 bool 1349 bool
1506 1350
1507 config RELR 1351 config RELR
1508 bool "Use RELR relocation packing" 1352 bool "Use RELR relocation packing"
1509 depends on ARCH_HAS_RELR && TOOLS_SUP 1353 depends on ARCH_HAS_RELR && TOOLS_SUPPORT_RELR
1510 default y 1354 default y
1511 help 1355 help
1512 Store the kernel's dynamic relocati 1356 Store the kernel's dynamic relocations in the RELR relocation packing
1513 format. Requires a compatible linke 1357 format. Requires a compatible linker (LLD supports this feature), as
1514 well as compatible NM and OBJCOPY u 1358 well as compatible NM and OBJCOPY utilities (llvm-nm and llvm-objcopy
1515 are compatible). 1359 are compatible).
1516 1360
1517 config ARCH_HAS_MEM_ENCRYPT 1361 config ARCH_HAS_MEM_ENCRYPT
1518 bool 1362 bool
1519 1363
1520 config ARCH_HAS_CC_PLATFORM 1364 config ARCH_HAS_CC_PLATFORM
1521 bool 1365 bool
1522 1366
1523 config HAVE_SPARSE_SYSCALL_NR 1367 config HAVE_SPARSE_SYSCALL_NR
1524 bool 1368 bool
1525 help 1369 help
1526 An architecture should select this 1370 An architecture should select this if its syscall numbering is sparse
1527 to save space. For example, MIPS ar 1371 to save space. For example, MIPS architecture has a syscall array with
1528 entries at 4000, 5000 and 6000 loca 1372 entries at 4000, 5000 and 6000 locations. This option turns on syscall
1529 related optimizations for a given a 1373 related optimizations for a given architecture.
1530 1374
1531 config ARCH_HAS_VDSO_DATA 1375 config ARCH_HAS_VDSO_DATA
1532 bool 1376 bool
1533 1377
1534 config HAVE_STATIC_CALL 1378 config HAVE_STATIC_CALL
1535 bool 1379 bool
1536 1380
1537 config HAVE_STATIC_CALL_INLINE 1381 config HAVE_STATIC_CALL_INLINE
1538 bool 1382 bool
1539 depends on HAVE_STATIC_CALL 1383 depends on HAVE_STATIC_CALL
1540 select OBJTOOL 1384 select OBJTOOL
1541 1385
1542 config HAVE_PREEMPT_DYNAMIC 1386 config HAVE_PREEMPT_DYNAMIC
1543 bool 1387 bool
1544 1388
1545 config HAVE_PREEMPT_DYNAMIC_CALL 1389 config HAVE_PREEMPT_DYNAMIC_CALL
1546 bool 1390 bool
1547 depends on HAVE_STATIC_CALL 1391 depends on HAVE_STATIC_CALL
1548 select HAVE_PREEMPT_DYNAMIC 1392 select HAVE_PREEMPT_DYNAMIC
1549 help 1393 help
1550 An architecture should select this 1394 An architecture should select this if it can handle the preemption
1551 model being selected at boot time u 1395 model being selected at boot time using static calls.
1552 1396
1553 Where an architecture selects HAVE_ 1397 Where an architecture selects HAVE_STATIC_CALL_INLINE, any call to a
1554 preemption function will be patched 1398 preemption function will be patched directly.
1555 1399
1556 Where an architecture does not sele 1400 Where an architecture does not select HAVE_STATIC_CALL_INLINE, any
1557 call to a preemption function will 1401 call to a preemption function will go through a trampoline, and the
1558 trampoline will be patched. 1402 trampoline will be patched.
1559 1403
1560 It is strongly advised to support i 1404 It is strongly advised to support inline static call to avoid any
1561 overhead. 1405 overhead.
1562 1406
1563 config HAVE_PREEMPT_DYNAMIC_KEY 1407 config HAVE_PREEMPT_DYNAMIC_KEY
1564 bool 1408 bool
1565 depends on HAVE_ARCH_JUMP_LABEL 1409 depends on HAVE_ARCH_JUMP_LABEL
1566 select HAVE_PREEMPT_DYNAMIC 1410 select HAVE_PREEMPT_DYNAMIC
1567 help 1411 help
1568 An architecture should select this 1412 An architecture should select this if it can handle the preemption
1569 model being selected at boot time u 1413 model being selected at boot time using static keys.
1570 1414
1571 Each preemption function will be gi 1415 Each preemption function will be given an early return based on a
1572 static key. This should have slight 1416 static key. This should have slightly lower overhead than non-inline
1573 static calls, as this effectively i 1417 static calls, as this effectively inlines each trampoline into the
1574 start of its callee. This may avoid 1418 start of its callee. This may avoid redundant work, and may
1575 integrate better with CFI schemes. 1419 integrate better with CFI schemes.
1576 1420
1577 This will have greater overhead tha 1421 This will have greater overhead than using inline static calls as
1578 the call to the preemption function 1422 the call to the preemption function cannot be entirely elided.
1579 1423
1580 config ARCH_WANT_LD_ORPHAN_WARN 1424 config ARCH_WANT_LD_ORPHAN_WARN
1581 bool 1425 bool
1582 help 1426 help
1583 An arch should select this symbol o 1427 An arch should select this symbol once all linker sections are explicitly
1584 included, size-asserted, or discard 1428 included, size-asserted, or discarded in the linker scripts. This is
1585 important because we never want exp 1429 important because we never want expected sections to be placed heuristically
1586 by the linker, since the locations 1430 by the linker, since the locations of such sections can change between linker
1587 versions. 1431 versions.
1588 1432
1589 config HAVE_ARCH_PFN_VALID 1433 config HAVE_ARCH_PFN_VALID
1590 bool 1434 bool
1591 1435
1592 config ARCH_SUPPORTS_DEBUG_PAGEALLOC 1436 config ARCH_SUPPORTS_DEBUG_PAGEALLOC
1593 bool 1437 bool
1594 1438
1595 config ARCH_SUPPORTS_PAGE_TABLE_CHECK 1439 config ARCH_SUPPORTS_PAGE_TABLE_CHECK
1596 bool 1440 bool
1597 1441
1598 config ARCH_SPLIT_ARG64 1442 config ARCH_SPLIT_ARG64
1599 bool 1443 bool
1600 help 1444 help
1601 If a 32-bit architecture requires 6 1445 If a 32-bit architecture requires 64-bit arguments to be split into
1602 pairs of 32-bit arguments, select t 1446 pairs of 32-bit arguments, select this option.
1603 1447
1604 config ARCH_HAS_ELFCORE_COMPAT 1448 config ARCH_HAS_ELFCORE_COMPAT
1605 bool 1449 bool
1606 1450
1607 config ARCH_HAS_PARANOID_L1D_FLUSH 1451 config ARCH_HAS_PARANOID_L1D_FLUSH
1608 bool 1452 bool
1609 1453
1610 config ARCH_HAVE_TRACE_MMIO_ACCESS 1454 config ARCH_HAVE_TRACE_MMIO_ACCESS
1611 bool 1455 bool
1612 1456
1613 config DYNAMIC_SIGFRAME 1457 config DYNAMIC_SIGFRAME
1614 bool 1458 bool
1615 1459
1616 # Select, if arch has a named attribute group 1460 # Select, if arch has a named attribute group bound to NUMA device nodes.
1617 config HAVE_ARCH_NODE_DEV_GROUP 1461 config HAVE_ARCH_NODE_DEV_GROUP
1618 bool 1462 bool
1619 1463
1620 config ARCH_HAS_HW_PTE_YOUNG <<
1621 bool <<
1622 help <<
1623 Architectures that select this opti <<
1624 accessed bit in PTE entries when us <<
1625 translations. Architectures that re <<
1626 this option and override arch_has_h <<
1627 <<
1628 config ARCH_HAS_NONLEAF_PMD_YOUNG 1464 config ARCH_HAS_NONLEAF_PMD_YOUNG
1629 bool 1465 bool
1630 help 1466 help
1631 Architectures that select this opti 1467 Architectures that select this option are capable of setting the
1632 accessed bit in non-leaf PMD entrie 1468 accessed bit in non-leaf PMD entries when using them as part of linear
1633 address translations. Page table wa 1469 address translations. Page table walkers that clear the accessed bit
1634 may use this capability to reduce t 1470 may use this capability to reduce their search space.
1635 1471
1636 config ARCH_HAS_KERNEL_FPU_SUPPORT <<
1637 bool <<
1638 help <<
1639 Architectures that select this opti <<
1640 the kernel, as described in Documen <<
1641 <<
1642 source "kernel/gcov/Kconfig" 1472 source "kernel/gcov/Kconfig"
1643 1473
1644 source "scripts/gcc-plugins/Kconfig" 1474 source "scripts/gcc-plugins/Kconfig"
1645 1475
1646 config FUNCTION_ALIGNMENT_4B 1476 config FUNCTION_ALIGNMENT_4B
1647 bool 1477 bool
1648 1478
1649 config FUNCTION_ALIGNMENT_8B 1479 config FUNCTION_ALIGNMENT_8B
1650 bool 1480 bool
1651 1481
1652 config FUNCTION_ALIGNMENT_16B 1482 config FUNCTION_ALIGNMENT_16B
1653 bool 1483 bool
1654 1484
1655 config FUNCTION_ALIGNMENT_32B 1485 config FUNCTION_ALIGNMENT_32B
1656 bool 1486 bool
1657 1487
1658 config FUNCTION_ALIGNMENT_64B 1488 config FUNCTION_ALIGNMENT_64B
1659 bool 1489 bool
1660 1490
1661 config FUNCTION_ALIGNMENT 1491 config FUNCTION_ALIGNMENT
1662 int 1492 int
1663 default 64 if FUNCTION_ALIGNMENT_64B 1493 default 64 if FUNCTION_ALIGNMENT_64B
1664 default 32 if FUNCTION_ALIGNMENT_32B 1494 default 32 if FUNCTION_ALIGNMENT_32B
1665 default 16 if FUNCTION_ALIGNMENT_16B 1495 default 16 if FUNCTION_ALIGNMENT_16B
1666 default 8 if FUNCTION_ALIGNMENT_8B 1496 default 8 if FUNCTION_ALIGNMENT_8B
1667 default 4 if FUNCTION_ALIGNMENT_4B 1497 default 4 if FUNCTION_ALIGNMENT_4B
1668 default 0 1498 default 0
1669 <<
1670 config CC_HAS_MIN_FUNCTION_ALIGNMENT <<
1671 # Detect availability of the GCC opti <<
1672 # guarantees minimal alignment for al <<
1673 # -falign-functions which the compile <<
1674 def_bool $(cc-option, -fmin-function- <<
1675 <<
1676 config CC_HAS_SANE_FUNCTION_ALIGNMENT <<
1677 # Set if the guaranteed alignment wit <<
1678 # available or extra care is required <<
1679 # strict alignment always, even with <<
1680 def_bool CC_HAS_MIN_FUNCTION_ALIGNMEN <<
1681 <<
1682 config ARCH_NEED_CMPXCHG_1_EMU <<
1683 bool <<
1684 1499
1685 endmenu 1500 endmenu
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