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