1 # SPDX-License-Identifier: GPL-2.0 1 # SPDX-License-Identifier: GPL-2.0
2 # 2 #
3 # General architecture dependent options 3 # General architecture dependent options
4 # 4 #
5 5
6 # 6 #
7 # Note: arch/$(SRCARCH)/Kconfig needs to be in 7 # Note: arch/$(SRCARCH)/Kconfig needs to be included first so that it can
8 # override the default values in this file. 8 # override the default values in this file.
9 # 9 #
10 source "arch/$(SRCARCH)/Kconfig" 10 source "arch/$(SRCARCH)/Kconfig"
11 11
12 config ARCH_CONFIGURES_CPU_MITIGATIONS !! 12 menu "General architecture-dependent options"
>> 13
>> 14 config CRASH_CORE
13 bool 15 bool
14 16
15 if !ARCH_CONFIGURES_CPU_MITIGATIONS !! 17 config KEXEC_CORE
16 config CPU_MITIGATIONS !! 18 select CRASH_CORE
17 def_bool y !! 19 bool
18 endif <<
19 20
20 # !! 21 config KEXEC_ELF
21 # Selected by architectures that need custom D <<
22 # IOMMUs not handled by dma-iommu. Drivers mu <<
23 # <<
24 config ARCH_HAS_DMA_OPS <<
25 depends on HAS_DMA <<
26 select DMA_OPS_HELPERS <<
27 bool 22 bool
28 23
29 menu "General architecture-dependent options" !! 24 config HAVE_IMA_KEXEC
>> 25 bool
30 26
31 config ARCH_HAS_SUBPAGE_FAULTS 27 config ARCH_HAS_SUBPAGE_FAULTS
32 bool 28 bool
33 help 29 help
34 Select if the architecture can check 30 Select if the architecture can check permissions at sub-page
35 granularity (e.g. arm64 MTE). The pr 31 granularity (e.g. arm64 MTE). The probe_user_*() functions
36 must be implemented. 32 must be implemented.
37 33
38 config HOTPLUG_SMT 34 config HOTPLUG_SMT
39 bool 35 bool
40 36
41 config SMT_NUM_THREADS_DYNAMIC <<
42 bool <<
43 <<
44 # Selected by HOTPLUG_CORE_SYNC_DEAD or HOTPLU <<
45 config HOTPLUG_CORE_SYNC <<
46 bool <<
47 <<
48 # Basic CPU dead synchronization selected by a <<
49 config HOTPLUG_CORE_SYNC_DEAD <<
50 bool <<
51 select HOTPLUG_CORE_SYNC <<
52 <<
53 # Full CPU synchronization with alive state se <<
54 config HOTPLUG_CORE_SYNC_FULL <<
55 bool <<
56 select HOTPLUG_CORE_SYNC_DEAD if HOTPL <<
57 select HOTPLUG_CORE_SYNC <<
58 <<
59 config HOTPLUG_SPLIT_STARTUP <<
60 bool <<
61 select HOTPLUG_CORE_SYNC_FULL <<
62 <<
63 config HOTPLUG_PARALLEL <<
64 bool <<
65 select HOTPLUG_SPLIT_STARTUP <<
66 <<
67 config GENERIC_ENTRY 37 config GENERIC_ENTRY
68 bool !! 38 bool
69 39
70 config KPROBES 40 config KPROBES
71 bool "Kprobes" 41 bool "Kprobes"
>> 42 depends on MODULES
72 depends on HAVE_KPROBES 43 depends on HAVE_KPROBES
73 select KALLSYMS 44 select KALLSYMS
74 select EXECMEM !! 45 select TASKS_RCU if PREEMPTION
75 select NEED_TASKS_RCU <<
76 help 46 help
77 Kprobes allows you to trap at almost 47 Kprobes allows you to trap at almost any kernel address and
78 execute a callback function. regist 48 execute a callback function. register_kprobe() establishes
79 a probepoint and specifies the callb 49 a probepoint and specifies the callback. Kprobes is useful
80 for kernel debugging, non-intrusive 50 for kernel debugging, non-intrusive instrumentation and testing.
81 If in doubt, say "N". 51 If in doubt, say "N".
82 52
83 config JUMP_LABEL 53 config JUMP_LABEL
84 bool "Optimize very unlikely/likely br 54 bool "Optimize very unlikely/likely branches"
85 depends on HAVE_ARCH_JUMP_LABEL 55 depends on HAVE_ARCH_JUMP_LABEL
86 select OBJTOOL if HAVE_JUMP_LABEL_HACK 56 select OBJTOOL if HAVE_JUMP_LABEL_HACK
87 help 57 help
88 This option enables a transparent br !! 58 This option enables a transparent branch optimization that
89 makes certain almost-always-true or !! 59 makes certain almost-always-true or almost-always-false branch
90 conditions even cheaper to execute w !! 60 conditions even cheaper to execute within the kernel.
91 !! 61
92 Certain performance-sensitive kernel !! 62 Certain performance-sensitive kernel code, such as trace points,
93 scheduler functionality, networking !! 63 scheduler functionality, networking code and KVM have such
94 branches and include support for thi !! 64 branches and include support for this optimization technique.
95 !! 65
96 If it is detected that the compiler !! 66 If it is detected that the compiler has support for "asm goto",
97 the kernel will compile such branche !! 67 the kernel will compile such branches with just a nop
98 instruction. When the condition flag !! 68 instruction. When the condition flag is toggled to true, the
99 nop will be converted to a jump inst !! 69 nop will be converted to a jump instruction to execute the
100 conditional block of instructions. !! 70 conditional block of instructions.
101 !! 71
102 This technique lowers overhead and s !! 72 This technique lowers overhead and stress on the branch prediction
103 of the processor and generally makes !! 73 of the processor and generally makes the kernel faster. The update
104 of the condition is slower, but thos !! 74 of the condition is slower, but those are always very rare.
105 75
106 ( On 32-bit x86, the necessary optio !! 76 ( On 32-bit x86, the necessary options added to the compiler
107 flags may increase the size of the !! 77 flags may increase the size of the kernel slightly. )
108 78
109 config STATIC_KEYS_SELFTEST 79 config STATIC_KEYS_SELFTEST
110 bool "Static key selftest" 80 bool "Static key selftest"
111 depends on JUMP_LABEL 81 depends on JUMP_LABEL
112 help 82 help
113 Boot time self-test of the branch pa 83 Boot time self-test of the branch patching code.
114 84
115 config STATIC_CALL_SELFTEST 85 config STATIC_CALL_SELFTEST
116 bool "Static call selftest" 86 bool "Static call selftest"
117 depends on HAVE_STATIC_CALL 87 depends on HAVE_STATIC_CALL
118 help 88 help
119 Boot time self-test of the call patc 89 Boot time self-test of the call patching code.
120 90
121 config OPTPROBES 91 config OPTPROBES
122 def_bool y 92 def_bool y
123 depends on KPROBES && HAVE_OPTPROBES 93 depends on KPROBES && HAVE_OPTPROBES
124 select NEED_TASKS_RCU !! 94 select TASKS_RCU if PREEMPTION
125 95
126 config KPROBES_ON_FTRACE 96 config KPROBES_ON_FTRACE
127 def_bool y 97 def_bool y
128 depends on KPROBES && HAVE_KPROBES_ON_ 98 depends on KPROBES && HAVE_KPROBES_ON_FTRACE
129 depends on DYNAMIC_FTRACE_WITH_REGS 99 depends on DYNAMIC_FTRACE_WITH_REGS
130 help 100 help
131 If function tracer is enabled and th !! 101 If function tracer is enabled and the arch supports full
132 passing of pt_regs to function traci !! 102 passing of pt_regs to function tracing, then kprobes can
133 optimize on top of function tracing. !! 103 optimize on top of function tracing.
134 104
135 config UPROBES 105 config UPROBES
136 def_bool n 106 def_bool n
137 depends on ARCH_SUPPORTS_UPROBES 107 depends on ARCH_SUPPORTS_UPROBES
138 help 108 help
139 Uprobes is the user-space counterpar 109 Uprobes is the user-space counterpart to kprobes: they
140 enable instrumentation applications 110 enable instrumentation applications (such as 'perf probe')
141 to establish unintrusive probes in u 111 to establish unintrusive probes in user-space binaries and
142 libraries, by executing handler func 112 libraries, by executing handler functions when the probes
143 are hit by user-space applications. 113 are hit by user-space applications.
144 114
145 ( These probes come in the form of s 115 ( These probes come in the form of single-byte breakpoints,
146 managed by the kernel and kept tra 116 managed by the kernel and kept transparent to the probed
147 application. ) 117 application. )
148 118
149 config HAVE_64BIT_ALIGNED_ACCESS 119 config HAVE_64BIT_ALIGNED_ACCESS
150 def_bool 64BIT && !HAVE_EFFICIENT_UNAL 120 def_bool 64BIT && !HAVE_EFFICIENT_UNALIGNED_ACCESS
151 help 121 help
152 Some architectures require 64 bit ac 122 Some architectures require 64 bit accesses to be 64 bit
153 aligned, which also requires structs 123 aligned, which also requires structs containing 64 bit values
154 to be 64 bit aligned too. This inclu 124 to be 64 bit aligned too. This includes some 32 bit
155 architectures which can do 64 bit ac 125 architectures which can do 64 bit accesses, as well as 64 bit
156 architectures without unaligned acce 126 architectures without unaligned access.
157 127
158 This symbol should be selected by an 128 This symbol should be selected by an architecture if 64 bit
159 accesses are required to be 64 bit a 129 accesses are required to be 64 bit aligned in this way even
160 though it is not a 64 bit architectu 130 though it is not a 64 bit architecture.
161 131
162 See Documentation/core-api/unaligned 132 See Documentation/core-api/unaligned-memory-access.rst for
163 more information on the topic of una 133 more information on the topic of unaligned memory accesses.
164 134
165 config HAVE_EFFICIENT_UNALIGNED_ACCESS 135 config HAVE_EFFICIENT_UNALIGNED_ACCESS
166 bool 136 bool
167 help 137 help
168 Some architectures are unable to per 138 Some architectures are unable to perform unaligned accesses
169 without the use of get_unaligned/put 139 without the use of get_unaligned/put_unaligned. Others are
170 unable to perform such accesses effi 140 unable to perform such accesses efficiently (e.g. trap on
171 unaligned access and require fixing 141 unaligned access and require fixing it up in the exception
172 handler.) 142 handler.)
173 143
174 This symbol should be selected by an 144 This symbol should be selected by an architecture if it can
175 perform unaligned accesses efficient 145 perform unaligned accesses efficiently to allow different
176 code paths to be selected for these 146 code paths to be selected for these cases. Some network
177 drivers, for example, could opt to n 147 drivers, for example, could opt to not fix up alignment
178 problems with received packets if do 148 problems with received packets if doing so would not help
179 much. 149 much.
180 150
181 See Documentation/core-api/unaligned 151 See Documentation/core-api/unaligned-memory-access.rst for more
182 information on the topic of unaligne 152 information on the topic of unaligned memory accesses.
183 153
184 config ARCH_USE_BUILTIN_BSWAP 154 config ARCH_USE_BUILTIN_BSWAP
185 bool 155 bool
186 help 156 help
187 Modern versions of GCC (since 4.4) h !! 157 Modern versions of GCC (since 4.4) have builtin functions
188 for handling byte-swapping. Using th !! 158 for handling byte-swapping. Using these, instead of the old
189 inline assembler that the architectu !! 159 inline assembler that the architecture code provides in the
190 __arch_bswapXX() macros, allows the !! 160 __arch_bswapXX() macros, allows the compiler to see what's
191 happening and offers more opportunit !! 161 happening and offers more opportunity for optimisation. In
192 particular, the compiler will be abl !! 162 particular, the compiler will be able to combine the byteswap
193 with a nearby load or store and use !! 163 with a nearby load or store and use load-and-swap or
194 store-and-swap instructions if the a !! 164 store-and-swap instructions if the architecture has them. It
195 should almost *never* result in code !! 165 should almost *never* result in code which is worse than the
196 hand-coded assembler in <asm/swab.h> !! 166 hand-coded assembler in <asm/swab.h>. But just in case it
197 does, the use of the builtins is opt !! 167 does, the use of the builtins is optional.
198 !! 168
199 Any architecture with load-and-swap !! 169 Any architecture with load-and-swap or store-and-swap
200 instructions should set this. And it !! 170 instructions should set this. And it shouldn't hurt to set it
201 on architectures that don't have suc !! 171 on architectures that don't have such instructions.
202 172
203 config KRETPROBES 173 config KRETPROBES
204 def_bool y 174 def_bool y
205 depends on KPROBES && (HAVE_KRETPROBES 175 depends on KPROBES && (HAVE_KRETPROBES || HAVE_RETHOOK)
206 176
207 config KRETPROBE_ON_RETHOOK 177 config KRETPROBE_ON_RETHOOK
208 def_bool y 178 def_bool y
209 depends on HAVE_RETHOOK 179 depends on HAVE_RETHOOK
210 depends on KRETPROBES 180 depends on KRETPROBES
211 select RETHOOK 181 select RETHOOK
212 182
213 config USER_RETURN_NOTIFIER 183 config USER_RETURN_NOTIFIER
214 bool 184 bool
215 depends on HAVE_USER_RETURN_NOTIFIER 185 depends on HAVE_USER_RETURN_NOTIFIER
216 help 186 help
217 Provide a kernel-internal notificati 187 Provide a kernel-internal notification when a cpu is about to
218 switch to user mode. 188 switch to user mode.
219 189
220 config HAVE_IOREMAP_PROT 190 config HAVE_IOREMAP_PROT
221 bool 191 bool
222 192
223 config HAVE_KPROBES 193 config HAVE_KPROBES
224 bool 194 bool
225 195
226 config HAVE_KRETPROBES 196 config HAVE_KRETPROBES
227 bool 197 bool
228 198
229 config HAVE_OPTPROBES 199 config HAVE_OPTPROBES
230 bool 200 bool
231 201
232 config HAVE_KPROBES_ON_FTRACE 202 config HAVE_KPROBES_ON_FTRACE
233 bool 203 bool
234 204
235 config ARCH_CORRECT_STACKTRACE_ON_KRETPROBE 205 config ARCH_CORRECT_STACKTRACE_ON_KRETPROBE
236 bool 206 bool
237 help 207 help
238 Since kretprobes modifies return add 208 Since kretprobes modifies return address on the stack, the
239 stacktrace may see the kretprobe tra 209 stacktrace may see the kretprobe trampoline address instead
240 of correct one. If the architecture 210 of correct one. If the architecture stacktrace code and
241 unwinder can adjust such entries, se 211 unwinder can adjust such entries, select this configuration.
242 212
243 config HAVE_FUNCTION_ERROR_INJECTION 213 config HAVE_FUNCTION_ERROR_INJECTION
244 bool 214 bool
245 215
246 config HAVE_NMI 216 config HAVE_NMI
247 bool 217 bool
248 218
249 config HAVE_FUNCTION_DESCRIPTORS 219 config HAVE_FUNCTION_DESCRIPTORS
250 bool 220 bool
251 221
252 config TRACE_IRQFLAGS_SUPPORT 222 config TRACE_IRQFLAGS_SUPPORT
253 bool 223 bool
254 224
255 config TRACE_IRQFLAGS_NMI_SUPPORT 225 config TRACE_IRQFLAGS_NMI_SUPPORT
256 bool 226 bool
257 227
258 # 228 #
259 # An arch should select this if it provides al 229 # An arch should select this if it provides all these things:
260 # 230 #
261 # task_pt_regs() in asm/process 231 # task_pt_regs() in asm/processor.h or asm/ptrace.h
262 # arch_has_single_step() if there is ha 232 # arch_has_single_step() if there is hardware single-step support
263 # arch_has_block_step() if there is ha 233 # arch_has_block_step() if there is hardware block-step support
264 # asm/syscall.h supplying asm- 234 # asm/syscall.h supplying asm-generic/syscall.h interface
265 # linux/regset.h user_regset in 235 # linux/regset.h user_regset interfaces
266 # CORE_DUMP_USE_REGSET #define'd in l 236 # CORE_DUMP_USE_REGSET #define'd in linux/elf.h
267 # TIF_SYSCALL_TRACE calls ptrace_r 237 # TIF_SYSCALL_TRACE calls ptrace_report_syscall_{entry,exit}
268 # TIF_NOTIFY_RESUME calls resume_u 238 # TIF_NOTIFY_RESUME calls resume_user_mode_work()
269 # 239 #
270 config HAVE_ARCH_TRACEHOOK 240 config HAVE_ARCH_TRACEHOOK
271 bool 241 bool
272 242
273 config HAVE_DMA_CONTIGUOUS 243 config HAVE_DMA_CONTIGUOUS
274 bool 244 bool
275 245
276 config GENERIC_SMP_IDLE_THREAD 246 config GENERIC_SMP_IDLE_THREAD
277 bool 247 bool
278 248
279 config GENERIC_IDLE_POLL_SETUP 249 config GENERIC_IDLE_POLL_SETUP
280 bool 250 bool
281 251
282 config ARCH_HAS_FORTIFY_SOURCE 252 config ARCH_HAS_FORTIFY_SOURCE
283 bool 253 bool
284 help 254 help
285 An architecture should select this w 255 An architecture should select this when it can successfully
286 build and run with CONFIG_FORTIFY_SO 256 build and run with CONFIG_FORTIFY_SOURCE.
287 257
288 # 258 #
289 # Select if the arch provides a historic keepi 259 # Select if the arch provides a historic keepinit alias for the retain_initrd
290 # command line option 260 # command line option
291 # 261 #
292 config ARCH_HAS_KEEPINITRD 262 config ARCH_HAS_KEEPINITRD
293 bool 263 bool
294 264
295 # Select if arch has all set_memory_ro/rw/x/nx 265 # Select if arch has all set_memory_ro/rw/x/nx() functions in asm/cacheflush.h
296 config ARCH_HAS_SET_MEMORY 266 config ARCH_HAS_SET_MEMORY
297 bool 267 bool
298 268
299 # Select if arch has all set_direct_map_invali 269 # Select if arch has all set_direct_map_invalid/default() functions
300 config ARCH_HAS_SET_DIRECT_MAP 270 config ARCH_HAS_SET_DIRECT_MAP
301 bool 271 bool
302 272
303 # 273 #
304 # Select if the architecture provides the arch 274 # Select if the architecture provides the arch_dma_set_uncached symbol to
305 # either provide an uncached segment alias for 275 # either provide an uncached segment alias for a DMA allocation, or
306 # to remap the page tables in place. 276 # to remap the page tables in place.
307 # 277 #
308 config ARCH_HAS_DMA_SET_UNCACHED 278 config ARCH_HAS_DMA_SET_UNCACHED
309 bool 279 bool
310 280
311 # 281 #
312 # Select if the architectures provides the arc 282 # Select if the architectures provides the arch_dma_clear_uncached symbol
313 # to undo an in-place page table remap for unc 283 # to undo an in-place page table remap for uncached access.
314 # 284 #
315 config ARCH_HAS_DMA_CLEAR_UNCACHED 285 config ARCH_HAS_DMA_CLEAR_UNCACHED
316 bool 286 bool
317 287
318 config ARCH_HAS_CPU_FINALIZE_INIT !! 288 # Select if arch init_task must go in the __init_task_data section
>> 289 config ARCH_TASK_STRUCT_ON_STACK
319 bool 290 bool
320 291
321 # The architecture has a per-task state that i !! 292 # Select if arch has its private alloc_task_struct() function
322 config ARCH_HAS_CPU_PASID !! 293 config ARCH_TASK_STRUCT_ALLOCATOR
323 bool 294 bool
324 select IOMMU_MM_DATA <<
325 295
326 config HAVE_ARCH_THREAD_STRUCT_WHITELIST 296 config HAVE_ARCH_THREAD_STRUCT_WHITELIST
327 bool 297 bool
>> 298 depends on !ARCH_TASK_STRUCT_ALLOCATOR
328 help 299 help
329 An architecture should select this t 300 An architecture should select this to provide hardened usercopy
330 knowledge about what region of the t 301 knowledge about what region of the thread_struct should be
331 whitelisted for copying to userspace 302 whitelisted for copying to userspace. Normally this is only the
332 FPU registers. Specifically, arch_th 303 FPU registers. Specifically, arch_thread_struct_whitelist()
333 should be implemented. Without this, 304 should be implemented. Without this, the entire thread_struct
334 field in task_struct will be left wh 305 field in task_struct will be left whitelisted.
335 306
>> 307 # Select if arch has its private alloc_thread_stack() function
>> 308 config ARCH_THREAD_STACK_ALLOCATOR
>> 309 bool
>> 310
336 # Select if arch wants to size task_struct dyn 311 # Select if arch wants to size task_struct dynamically via arch_task_struct_size:
337 config ARCH_WANTS_DYNAMIC_TASK_STRUCT 312 config ARCH_WANTS_DYNAMIC_TASK_STRUCT
338 bool 313 bool
339 314
340 config ARCH_WANTS_NO_INSTR 315 config ARCH_WANTS_NO_INSTR
341 bool 316 bool
342 help 317 help
343 An architecture should select this i 318 An architecture should select this if the noinstr macro is being used on
344 functions to denote that the toolcha 319 functions to denote that the toolchain should avoid instrumenting such
345 functions and is required for correc 320 functions and is required for correctness.
346 321
347 config ARCH_32BIT_OFF_T 322 config ARCH_32BIT_OFF_T
348 bool 323 bool
349 depends on !64BIT 324 depends on !64BIT
350 help 325 help
351 All new 32-bit architectures should 326 All new 32-bit architectures should have 64-bit off_t type on
352 userspace side which corresponds to 327 userspace side which corresponds to the loff_t kernel type. This
353 is the requirement for modern ABIs. 328 is the requirement for modern ABIs. Some existing architectures
354 still support 32-bit off_t. This opt 329 still support 32-bit off_t. This option is enabled for all such
355 architectures explicitly. 330 architectures explicitly.
356 331
357 # Selected by 64 bit architectures which have 332 # Selected by 64 bit architectures which have a 32 bit f_tinode in struct ustat
358 config ARCH_32BIT_USTAT_F_TINODE 333 config ARCH_32BIT_USTAT_F_TINODE
359 bool 334 bool
360 335
361 config HAVE_ASM_MODVERSIONS 336 config HAVE_ASM_MODVERSIONS
362 bool 337 bool
363 help 338 help
364 This symbol should be selected by an 339 This symbol should be selected by an architecture if it provides
365 <asm/asm-prototypes.h> to support th 340 <asm/asm-prototypes.h> to support the module versioning for symbols
366 exported from assembly code. 341 exported from assembly code.
367 342
368 config HAVE_REGS_AND_STACK_ACCESS_API 343 config HAVE_REGS_AND_STACK_ACCESS_API
369 bool 344 bool
370 help 345 help
371 This symbol should be selected by an 346 This symbol should be selected by an architecture if it supports
372 the API needed to access registers a 347 the API needed to access registers and stack entries from pt_regs,
373 declared in asm/ptrace.h 348 declared in asm/ptrace.h
374 For example the kprobes-based event 349 For example the kprobes-based event tracer needs this API.
375 350
376 config HAVE_RSEQ 351 config HAVE_RSEQ
377 bool 352 bool
378 depends on HAVE_REGS_AND_STACK_ACCESS_ 353 depends on HAVE_REGS_AND_STACK_ACCESS_API
379 help 354 help
380 This symbol should be selected by an 355 This symbol should be selected by an architecture if it
381 supports an implementation of restar 356 supports an implementation of restartable sequences.
382 357
383 config HAVE_RUST 358 config HAVE_RUST
384 bool 359 bool
385 help 360 help
386 This symbol should be selected by an 361 This symbol should be selected by an architecture if it
387 supports Rust. 362 supports Rust.
388 363
389 config HAVE_FUNCTION_ARG_ACCESS_API 364 config HAVE_FUNCTION_ARG_ACCESS_API
390 bool 365 bool
391 help 366 help
392 This symbol should be selected by an 367 This symbol should be selected by an architecture if it supports
393 the API needed to access function ar 368 the API needed to access function arguments from pt_regs,
394 declared in asm/ptrace.h 369 declared in asm/ptrace.h
395 370
396 config HAVE_HW_BREAKPOINT 371 config HAVE_HW_BREAKPOINT
397 bool 372 bool
398 depends on PERF_EVENTS 373 depends on PERF_EVENTS
399 374
400 config HAVE_MIXED_BREAKPOINTS_REGS 375 config HAVE_MIXED_BREAKPOINTS_REGS
401 bool 376 bool
402 depends on HAVE_HW_BREAKPOINT 377 depends on HAVE_HW_BREAKPOINT
403 help 378 help
404 Depending on the arch implementation 379 Depending on the arch implementation of hardware breakpoints,
405 some of them have separate registers 380 some of them have separate registers for data and instruction
406 breakpoints addresses, others have m 381 breakpoints addresses, others have mixed registers to store
407 them but define the access type in a 382 them but define the access type in a control register.
408 Select this option if your arch impl 383 Select this option if your arch implements breakpoints under the
409 latter fashion. 384 latter fashion.
410 385
411 config HAVE_USER_RETURN_NOTIFIER 386 config HAVE_USER_RETURN_NOTIFIER
412 bool 387 bool
413 388
414 config HAVE_PERF_EVENTS_NMI 389 config HAVE_PERF_EVENTS_NMI
415 bool 390 bool
416 help 391 help
417 System hardware can generate an NMI 392 System hardware can generate an NMI using the perf event
418 subsystem. Also has support for cal 393 subsystem. Also has support for calculating CPU cycle events
419 to determine how many clock cycles i 394 to determine how many clock cycles in a given period.
420 395
421 config HAVE_HARDLOCKUP_DETECTOR_PERF 396 config HAVE_HARDLOCKUP_DETECTOR_PERF
422 bool 397 bool
423 depends on HAVE_PERF_EVENTS_NMI 398 depends on HAVE_PERF_EVENTS_NMI
424 help 399 help
425 The arch chooses to use the generic 400 The arch chooses to use the generic perf-NMI-based hardlockup
426 detector. Must define HAVE_PERF_EVEN 401 detector. Must define HAVE_PERF_EVENTS_NMI.
427 402
428 config HAVE_HARDLOCKUP_DETECTOR_ARCH !! 403 config HAVE_NMI_WATCHDOG
>> 404 depends on HAVE_NMI
429 bool 405 bool
430 help 406 help
431 The arch provides its own hardlockup !! 407 The arch provides a low level NMI watchdog. It provides
432 of the generic ones. !! 408 asm/nmi.h, and defines its own arch_touch_nmi_watchdog().
433 409
434 It uses the same command line parame !! 410 config HAVE_HARDLOCKUP_DETECTOR_ARCH
435 as the generic hardlockup detectors. !! 411 bool
>> 412 select HAVE_NMI_WATCHDOG
>> 413 help
>> 414 The arch chooses to provide its own hardlockup detector, which is
>> 415 a superset of the HAVE_NMI_WATCHDOG. It also conforms to config
>> 416 interfaces and parameters provided by hardlockup detector subsystem.
436 417
437 config HAVE_PERF_REGS 418 config HAVE_PERF_REGS
438 bool 419 bool
439 help 420 help
440 Support selective register dumps for 421 Support selective register dumps for perf events. This includes
441 bit-mapping of each registers and a 422 bit-mapping of each registers and a unique architecture id.
442 423
443 config HAVE_PERF_USER_STACK_DUMP 424 config HAVE_PERF_USER_STACK_DUMP
444 bool 425 bool
445 help 426 help
446 Support user stack dumps for perf ev 427 Support user stack dumps for perf event samples. This needs
447 access to the user stack pointer whi 428 access to the user stack pointer which is not unified across
448 architectures. 429 architectures.
449 430
450 config HAVE_ARCH_JUMP_LABEL 431 config HAVE_ARCH_JUMP_LABEL
451 bool 432 bool
452 433
453 config HAVE_ARCH_JUMP_LABEL_RELATIVE 434 config HAVE_ARCH_JUMP_LABEL_RELATIVE
454 bool 435 bool
455 436
456 config MMU_GATHER_TABLE_FREE 437 config MMU_GATHER_TABLE_FREE
457 bool 438 bool
458 439
459 config MMU_GATHER_RCU_TABLE_FREE 440 config MMU_GATHER_RCU_TABLE_FREE
460 bool 441 bool
461 select MMU_GATHER_TABLE_FREE 442 select MMU_GATHER_TABLE_FREE
462 443
463 config MMU_GATHER_PAGE_SIZE 444 config MMU_GATHER_PAGE_SIZE
464 bool 445 bool
465 446
466 config MMU_GATHER_NO_RANGE 447 config MMU_GATHER_NO_RANGE
467 bool 448 bool
468 select MMU_GATHER_MERGE_VMAS 449 select MMU_GATHER_MERGE_VMAS
469 450
470 config MMU_GATHER_NO_FLUSH_CACHE 451 config MMU_GATHER_NO_FLUSH_CACHE
471 bool 452 bool
472 453
473 config MMU_GATHER_MERGE_VMAS 454 config MMU_GATHER_MERGE_VMAS
474 bool 455 bool
475 456
476 config MMU_GATHER_NO_GATHER 457 config MMU_GATHER_NO_GATHER
477 bool 458 bool
478 depends on MMU_GATHER_TABLE_FREE 459 depends on MMU_GATHER_TABLE_FREE
479 460
480 config ARCH_WANT_IRQS_OFF_ACTIVATE_MM 461 config ARCH_WANT_IRQS_OFF_ACTIVATE_MM
481 bool 462 bool
482 help 463 help
483 Temporary select until all architect 464 Temporary select until all architectures can be converted to have
484 irqs disabled over activate_mm. Arch 465 irqs disabled over activate_mm. Architectures that do IPI based TLB
485 shootdowns should enable this. 466 shootdowns should enable this.
486 467
487 # Use normal mm refcounting for MMU_LAZY_TLB k <<
488 # MMU_LAZY_TLB_REFCOUNT=n can improve the scal <<
489 # to/from kernel threads when the same mm is r <<
490 # multi-threaded application), by reducing con <<
491 # <<
492 # This can be disabled if the architecture ens <<
493 # "lazy tlb" beyond its final refcount (i.e., <<
494 # or its kernel page tables). This could be ar <<
495 # final exit(2) TLB flush, for example. <<
496 # <<
497 # To implement this, an arch *must*: <<
498 # Ensure the _lazy_tlb variants of mmgrab/mmdr <<
499 # the lazy tlb reference of a kthread's ->acti <<
500 # converted already). <<
501 config MMU_LAZY_TLB_REFCOUNT <<
502 def_bool y <<
503 depends on !MMU_LAZY_TLB_SHOOTDOWN <<
504 <<
505 # This option allows MMU_LAZY_TLB_REFCOUNT=n. <<
506 # mm as a lazy tlb beyond its last reference c <<
507 # users before the mm is deallocated. __mmdrop <<
508 # be using the mm as a lazy tlb, so that they <<
509 # init_mm for their active mm. mm_cpumask(mm) <<
510 # may be using mm as a lazy tlb mm. <<
511 # <<
512 # To implement this, an arch *must*: <<
513 # - At the time of the final mmdrop of the mm, <<
514 # at least all possible CPUs in which the mm <<
515 # - It must meet the requirements for MMU_LAZY <<
516 config MMU_LAZY_TLB_SHOOTDOWN <<
517 bool <<
518 <<
519 config ARCH_HAVE_NMI_SAFE_CMPXCHG 468 config ARCH_HAVE_NMI_SAFE_CMPXCHG
520 bool 469 bool
521 470
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 471 config ARCH_HAS_NMI_SAFE_THIS_CPU_OPS
532 bool 472 bool
533 473
534 config HAVE_ALIGNED_STRUCT_PAGE 474 config HAVE_ALIGNED_STRUCT_PAGE
535 bool 475 bool
536 help 476 help
537 This makes sure that struct pages ar 477 This makes sure that struct pages are double word aligned and that
538 e.g. the SLUB allocator can perform 478 e.g. the SLUB allocator can perform double word atomic operations
539 on a struct page for better performa 479 on a struct page for better performance. However selecting this
540 might increase the size of a struct 480 might increase the size of a struct page by a word.
541 481
542 config HAVE_CMPXCHG_LOCAL 482 config HAVE_CMPXCHG_LOCAL
543 bool 483 bool
544 484
545 config HAVE_CMPXCHG_DOUBLE 485 config HAVE_CMPXCHG_DOUBLE
546 bool 486 bool
547 487
548 config ARCH_WEAK_RELEASE_ACQUIRE 488 config ARCH_WEAK_RELEASE_ACQUIRE
549 bool 489 bool
550 490
551 config ARCH_WANT_IPC_PARSE_VERSION 491 config ARCH_WANT_IPC_PARSE_VERSION
552 bool 492 bool
553 493
554 config ARCH_WANT_COMPAT_IPC_PARSE_VERSION 494 config ARCH_WANT_COMPAT_IPC_PARSE_VERSION
555 bool 495 bool
556 496
557 config ARCH_WANT_OLD_COMPAT_IPC 497 config ARCH_WANT_OLD_COMPAT_IPC
558 select ARCH_WANT_COMPAT_IPC_PARSE_VERS 498 select ARCH_WANT_COMPAT_IPC_PARSE_VERSION
559 bool 499 bool
560 500
561 config HAVE_ARCH_SECCOMP 501 config HAVE_ARCH_SECCOMP
562 bool 502 bool
563 help 503 help
564 An arch should select this symbol to 504 An arch should select this symbol to support seccomp mode 1 (the fixed
565 syscall policy), and must provide an 505 syscall policy), and must provide an overrides for __NR_seccomp_sigreturn,
566 and compat syscalls if the asm-gener 506 and compat syscalls if the asm-generic/seccomp.h defaults need adjustment:
567 - __NR_seccomp_read_32 507 - __NR_seccomp_read_32
568 - __NR_seccomp_write_32 508 - __NR_seccomp_write_32
569 - __NR_seccomp_exit_32 509 - __NR_seccomp_exit_32
570 - __NR_seccomp_sigreturn_32 510 - __NR_seccomp_sigreturn_32
571 511
572 config HAVE_ARCH_SECCOMP_FILTER 512 config HAVE_ARCH_SECCOMP_FILTER
573 bool 513 bool
574 select HAVE_ARCH_SECCOMP 514 select HAVE_ARCH_SECCOMP
575 help 515 help
576 An arch should select this symbol if 516 An arch should select this symbol if it provides all of these things:
577 - all the requirements for HAVE_ARCH 517 - all the requirements for HAVE_ARCH_SECCOMP
578 - syscall_get_arch() 518 - syscall_get_arch()
579 - syscall_get_arguments() 519 - syscall_get_arguments()
580 - syscall_rollback() 520 - syscall_rollback()
581 - syscall_set_return_value() 521 - syscall_set_return_value()
582 - SIGSYS siginfo_t support 522 - SIGSYS siginfo_t support
583 - secure_computing is called from a 523 - secure_computing is called from a ptrace_event()-safe context
584 - secure_computing return value is c 524 - secure_computing return value is checked and a return value of -1
585 results in the system call being s 525 results in the system call being skipped immediately.
586 - seccomp syscall wired up 526 - seccomp syscall wired up
587 - if !HAVE_SPARSE_SYSCALL_NR, have S 527 - if !HAVE_SPARSE_SYSCALL_NR, have SECCOMP_ARCH_NATIVE,
588 SECCOMP_ARCH_NATIVE_NR, SECCOMP_AR 528 SECCOMP_ARCH_NATIVE_NR, SECCOMP_ARCH_NATIVE_NAME defined. If
589 COMPAT is supported, have the SECC 529 COMPAT is supported, have the SECCOMP_ARCH_COMPAT* defines too.
590 530
591 config SECCOMP 531 config SECCOMP
592 prompt "Enable seccomp to safely execu 532 prompt "Enable seccomp to safely execute untrusted bytecode"
593 def_bool y 533 def_bool y
594 depends on HAVE_ARCH_SECCOMP 534 depends on HAVE_ARCH_SECCOMP
595 help 535 help
596 This kernel feature is useful for nu 536 This kernel feature is useful for number crunching applications
597 that may need to handle untrusted by 537 that may need to handle untrusted bytecode during their
598 execution. By using pipes or other t 538 execution. By using pipes or other transports made available
599 to the process as file descriptors s 539 to the process as file descriptors supporting the read/write
600 syscalls, it's possible to isolate t 540 syscalls, it's possible to isolate those applications in their
601 own address space using seccomp. Onc 541 own address space using seccomp. Once seccomp is enabled via
602 prctl(PR_SET_SECCOMP) or the seccomp 542 prctl(PR_SET_SECCOMP) or the seccomp() syscall, it cannot be
603 disabled and the task is only allowe 543 disabled and the task is only allowed to execute a few safe
604 syscalls defined by each seccomp mod 544 syscalls defined by each seccomp mode.
605 545
606 If unsure, say Y. 546 If unsure, say Y.
607 547
608 config SECCOMP_FILTER 548 config SECCOMP_FILTER
609 def_bool y 549 def_bool y
610 depends on HAVE_ARCH_SECCOMP_FILTER && 550 depends on HAVE_ARCH_SECCOMP_FILTER && SECCOMP && NET
611 help 551 help
612 Enable tasks to build secure computi 552 Enable tasks to build secure computing environments defined
613 in terms of Berkeley Packet Filter p 553 in terms of Berkeley Packet Filter programs which implement
614 task-defined system call filtering p 554 task-defined system call filtering polices.
615 555
616 See Documentation/userspace-api/secc 556 See Documentation/userspace-api/seccomp_filter.rst for details.
617 557
618 config SECCOMP_CACHE_DEBUG 558 config SECCOMP_CACHE_DEBUG
619 bool "Show seccomp filter cache status 559 bool "Show seccomp filter cache status in /proc/pid/seccomp_cache"
620 depends on SECCOMP_FILTER && !HAVE_SPA 560 depends on SECCOMP_FILTER && !HAVE_SPARSE_SYSCALL_NR
621 depends on PROC_FS 561 depends on PROC_FS
622 help 562 help
623 This enables the /proc/pid/seccomp_c 563 This enables the /proc/pid/seccomp_cache interface to monitor
624 seccomp cache data. The file format 564 seccomp cache data. The file format is subject to change. Reading
625 the file requires CAP_SYS_ADMIN. 565 the file requires CAP_SYS_ADMIN.
626 566
627 This option is for debugging only. E 567 This option is for debugging only. Enabling presents the risk that
628 an adversary may be able to infer th 568 an adversary may be able to infer the seccomp filter logic.
629 569
630 If unsure, say N. 570 If unsure, say N.
631 571
632 config HAVE_ARCH_STACKLEAK 572 config HAVE_ARCH_STACKLEAK
633 bool 573 bool
634 help 574 help
635 An architecture should select this i 575 An architecture should select this if it has the code which
636 fills the used part of the kernel st 576 fills the used part of the kernel stack with the STACKLEAK_POISON
637 value before returning from system c 577 value before returning from system calls.
638 578
639 config HAVE_STACKPROTECTOR 579 config HAVE_STACKPROTECTOR
640 bool 580 bool
641 help 581 help
642 An arch should select this symbol if 582 An arch should select this symbol if:
643 - it has implemented a stack canary 583 - it has implemented a stack canary (e.g. __stack_chk_guard)
644 584
645 config STACKPROTECTOR 585 config STACKPROTECTOR
646 bool "Stack Protector buffer overflow 586 bool "Stack Protector buffer overflow detection"
647 depends on HAVE_STACKPROTECTOR 587 depends on HAVE_STACKPROTECTOR
648 depends on $(cc-option,-fstack-protect 588 depends on $(cc-option,-fstack-protector)
649 default y 589 default y
650 help 590 help
651 This option turns on the "stack-prot 591 This option turns on the "stack-protector" GCC feature. This
652 feature puts, at the beginning of fu 592 feature puts, at the beginning of functions, a canary value on
653 the stack just before the return add 593 the stack just before the return address, and validates
654 the value just before actually retur 594 the value just before actually returning. Stack based buffer
655 overflows (that need to overwrite th 595 overflows (that need to overwrite this return address) now also
656 overwrite the canary, which gets det 596 overwrite the canary, which gets detected and the attack is then
657 neutralized via a kernel panic. 597 neutralized via a kernel panic.
658 598
659 Functions will have the stack-protec 599 Functions will have the stack-protector canary logic added if they
660 have an 8-byte or larger character a 600 have an 8-byte or larger character array on the stack.
661 601
662 This feature requires gcc version 4. 602 This feature requires gcc version 4.2 or above, or a distribution
663 gcc with the feature backported ("-f 603 gcc with the feature backported ("-fstack-protector").
664 604
665 On an x86 "defconfig" build, this fe 605 On an x86 "defconfig" build, this feature adds canary checks to
666 about 3% of all kernel functions, wh 606 about 3% of all kernel functions, which increases kernel code size
667 by about 0.3%. 607 by about 0.3%.
668 608
669 config STACKPROTECTOR_STRONG 609 config STACKPROTECTOR_STRONG
670 bool "Strong Stack Protector" 610 bool "Strong Stack Protector"
671 depends on STACKPROTECTOR 611 depends on STACKPROTECTOR
672 depends on $(cc-option,-fstack-protect 612 depends on $(cc-option,-fstack-protector-strong)
673 default y 613 default y
674 help 614 help
675 Functions will have the stack-protec 615 Functions will have the stack-protector canary logic added in any
676 of the following conditions: 616 of the following conditions:
677 617
678 - local variable's address used as p 618 - local variable's address used as part of the right hand side of an
679 assignment or function argument 619 assignment or function argument
680 - local variable is an array (or uni 620 - local variable is an array (or union containing an array),
681 regardless of array type or length 621 regardless of array type or length
682 - uses register local variables 622 - uses register local variables
683 623
684 This feature requires gcc version 4. 624 This feature requires gcc version 4.9 or above, or a distribution
685 gcc with the feature backported ("-f 625 gcc with the feature backported ("-fstack-protector-strong").
686 626
687 On an x86 "defconfig" build, this fe 627 On an x86 "defconfig" build, this feature adds canary checks to
688 about 20% of all kernel functions, w 628 about 20% of all kernel functions, which increases the kernel code
689 size by about 2%. 629 size by about 2%.
690 630
691 config ARCH_SUPPORTS_SHADOW_CALL_STACK 631 config ARCH_SUPPORTS_SHADOW_CALL_STACK
692 bool 632 bool
693 help 633 help
694 An architecture should select this i 634 An architecture should select this if it supports the compiler's
695 Shadow Call Stack and implements run 635 Shadow Call Stack and implements runtime support for shadow stack
696 switching. 636 switching.
697 637
698 config SHADOW_CALL_STACK 638 config SHADOW_CALL_STACK
699 bool "Shadow Call Stack" 639 bool "Shadow Call Stack"
700 depends on ARCH_SUPPORTS_SHADOW_CALL_S 640 depends on ARCH_SUPPORTS_SHADOW_CALL_STACK
701 depends on DYNAMIC_FTRACE_WITH_ARGS || 641 depends on DYNAMIC_FTRACE_WITH_ARGS || DYNAMIC_FTRACE_WITH_REGS || !FUNCTION_GRAPH_TRACER
702 depends on MMU <<
703 help 642 help
704 This option enables the compiler's S 643 This option enables the compiler's Shadow Call Stack, which
705 uses a shadow stack to protect funct 644 uses a shadow stack to protect function return addresses from
706 being overwritten by an attacker. Mo 645 being overwritten by an attacker. More information can be found
707 in the compiler's documentation: 646 in the compiler's documentation:
708 647
709 - Clang: https://clang.llvm.org/docs 648 - Clang: https://clang.llvm.org/docs/ShadowCallStack.html
710 - GCC: https://gcc.gnu.org/onlinedoc 649 - GCC: https://gcc.gnu.org/onlinedocs/gcc/Instrumentation-Options.html#Instrumentation-Options
711 650
712 Note that security guarantees in the 651 Note that security guarantees in the kernel differ from the
713 ones documented for user space. The 652 ones documented for user space. The kernel must store addresses
714 of shadow stacks in memory, which me 653 of shadow stacks in memory, which means an attacker capable of
715 reading and writing arbitrary memory 654 reading and writing arbitrary memory may be able to locate them
716 and hijack control flow by modifying 655 and hijack control flow by modifying the stacks.
717 656
718 config DYNAMIC_SCS 657 config DYNAMIC_SCS
719 bool 658 bool
720 help 659 help
721 Set by the arch code if it relies on 660 Set by the arch code if it relies on code patching to insert the
722 shadow call stack push and pop instr 661 shadow call stack push and pop instructions rather than on the
723 compiler. 662 compiler.
724 663
725 config LTO 664 config LTO
726 bool 665 bool
727 help 666 help
728 Selected if the kernel will be built 667 Selected if the kernel will be built using the compiler's LTO feature.
729 668
730 config LTO_CLANG 669 config LTO_CLANG
731 bool 670 bool
732 select LTO 671 select LTO
733 help 672 help
734 Selected if the kernel will be built 673 Selected if the kernel will be built using Clang's LTO feature.
735 674
736 config ARCH_SUPPORTS_LTO_CLANG 675 config ARCH_SUPPORTS_LTO_CLANG
737 bool 676 bool
738 help 677 help
739 An architecture should select this o 678 An architecture should select this option if it supports:
740 - compiling with Clang, 679 - compiling with Clang,
741 - compiling inline assembly with Cla 680 - compiling inline assembly with Clang's integrated assembler,
742 - and linking with LLD. 681 - and linking with LLD.
743 682
744 config ARCH_SUPPORTS_LTO_CLANG_THIN 683 config ARCH_SUPPORTS_LTO_CLANG_THIN
745 bool 684 bool
746 help 685 help
747 An architecture should select this o 686 An architecture should select this option if it can support Clang's
748 ThinLTO mode. 687 ThinLTO mode.
749 688
750 config HAS_LTO_CLANG 689 config HAS_LTO_CLANG
751 def_bool y 690 def_bool y
752 depends on CC_IS_CLANG && LD_IS_LLD && 691 depends on CC_IS_CLANG && LD_IS_LLD && AS_IS_LLVM
753 depends on $(success,$(NM) --help | he 692 depends on $(success,$(NM) --help | head -n 1 | grep -qi llvm)
754 depends on $(success,$(AR) --help | he 693 depends on $(success,$(AR) --help | head -n 1 | grep -qi llvm)
755 depends on ARCH_SUPPORTS_LTO_CLANG 694 depends on ARCH_SUPPORTS_LTO_CLANG
756 depends on !FTRACE_MCOUNT_USE_RECORDMC 695 depends on !FTRACE_MCOUNT_USE_RECORDMCOUNT
757 # https://github.com/ClangBuiltLinux/l !! 696 depends on !KASAN || KASAN_HW_TAGS
758 depends on (!KASAN || KASAN_HW_TAGS || <<
759 depends on (!KCOV || CLANG_VERSION >= <<
760 depends on !GCOV_KERNEL 697 depends on !GCOV_KERNEL
761 help 698 help
762 The compiler and Kconfig options sup 699 The compiler and Kconfig options support building with Clang's
763 LTO. 700 LTO.
764 701
765 choice 702 choice
766 prompt "Link Time Optimization (LTO)" 703 prompt "Link Time Optimization (LTO)"
767 default LTO_NONE 704 default LTO_NONE
768 help 705 help
769 This option enables Link Time Optimi 706 This option enables Link Time Optimization (LTO), which allows the
770 compiler to optimize binaries global 707 compiler to optimize binaries globally.
771 708
772 If unsure, select LTO_NONE. Note tha 709 If unsure, select LTO_NONE. Note that LTO is very resource-intensive
773 so it's disabled by default. 710 so it's disabled by default.
774 711
775 config LTO_NONE 712 config LTO_NONE
776 bool "None" 713 bool "None"
777 help 714 help
778 Build the kernel normally, without L 715 Build the kernel normally, without Link Time Optimization (LTO).
779 716
780 config LTO_CLANG_FULL 717 config LTO_CLANG_FULL
781 bool "Clang Full LTO (EXPERIMENTAL)" 718 bool "Clang Full LTO (EXPERIMENTAL)"
782 depends on HAS_LTO_CLANG 719 depends on HAS_LTO_CLANG
783 depends on !COMPILE_TEST 720 depends on !COMPILE_TEST
784 select LTO_CLANG 721 select LTO_CLANG
785 help 722 help
786 This option enables Clang's full Lin !! 723 This option enables Clang's full Link Time Optimization (LTO), which
787 allows the compiler to optimize the !! 724 allows the compiler to optimize the kernel globally. If you enable
788 this option, the compiler generates !! 725 this option, the compiler generates LLVM bitcode instead of ELF
789 object files, and the actual compila !! 726 object files, and the actual compilation from bitcode happens at
790 the LTO link step, which may take se !! 727 the LTO link step, which may take several minutes depending on the
791 kernel configuration. More informati !! 728 kernel configuration. More information can be found from LLVM's
792 documentation: !! 729 documentation:
793 730
794 https://llvm.org/docs/LinkTimeOpti 731 https://llvm.org/docs/LinkTimeOptimization.html
795 732
796 During link time, this option can us 733 During link time, this option can use a large amount of RAM, and
797 may take much longer than the ThinLT 734 may take much longer than the ThinLTO option.
798 735
799 config LTO_CLANG_THIN 736 config LTO_CLANG_THIN
800 bool "Clang ThinLTO (EXPERIMENTAL)" 737 bool "Clang ThinLTO (EXPERIMENTAL)"
801 depends on HAS_LTO_CLANG && ARCH_SUPPO 738 depends on HAS_LTO_CLANG && ARCH_SUPPORTS_LTO_CLANG_THIN
802 select LTO_CLANG 739 select LTO_CLANG
803 help 740 help
804 This option enables Clang's ThinLTO, 741 This option enables Clang's ThinLTO, which allows for parallel
805 optimization and faster incremental 742 optimization and faster incremental compiles compared to the
806 CONFIG_LTO_CLANG_FULL option. More i 743 CONFIG_LTO_CLANG_FULL option. More information can be found
807 from Clang's documentation: 744 from Clang's documentation:
808 745
809 https://clang.llvm.org/docs/ThinLT 746 https://clang.llvm.org/docs/ThinLTO.html
810 747
811 If unsure, say Y. 748 If unsure, say Y.
812 endchoice 749 endchoice
813 750
814 config ARCH_SUPPORTS_CFI_CLANG 751 config ARCH_SUPPORTS_CFI_CLANG
815 bool 752 bool
816 help 753 help
817 An architecture should select this o 754 An architecture should select this option if it can support Clang's
818 Control-Flow Integrity (CFI) checkin 755 Control-Flow Integrity (CFI) checking.
819 756
820 config ARCH_USES_CFI_TRAPS 757 config ARCH_USES_CFI_TRAPS
821 bool 758 bool
822 759
823 config CFI_CLANG 760 config CFI_CLANG
824 bool "Use Clang's Control Flow Integri 761 bool "Use Clang's Control Flow Integrity (CFI)"
825 depends on ARCH_SUPPORTS_CFI_CLANG 762 depends on ARCH_SUPPORTS_CFI_CLANG
826 depends on $(cc-option,-fsanitize=kcfi 763 depends on $(cc-option,-fsanitize=kcfi)
827 help 764 help
828 This option enables Clang's forward- !! 765 This option enables Clang’s forward-edge Control Flow Integrity
829 (CFI) checking, where the compiler i 766 (CFI) checking, where the compiler injects a runtime check to each
830 indirect function call to ensure the 767 indirect function call to ensure the target is a valid function with
831 the correct static type. This restri 768 the correct static type. This restricts possible call targets and
832 makes it more difficult for an attac 769 makes it more difficult for an attacker to exploit bugs that allow
833 the modification of stored function 770 the modification of stored function pointers. More information can be
834 found from Clang's documentation: 771 found from Clang's documentation:
835 772
836 https://clang.llvm.org/docs/Contro 773 https://clang.llvm.org/docs/ControlFlowIntegrity.html
837 774
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 775 config CFI_PERMISSIVE
869 bool "Use CFI in permissive mode" 776 bool "Use CFI in permissive mode"
870 depends on CFI_CLANG 777 depends on CFI_CLANG
871 help 778 help
872 When selected, Control Flow Integrit 779 When selected, Control Flow Integrity (CFI) violations result in a
873 warning instead of a kernel panic. T 780 warning instead of a kernel panic. This option should only be used
874 for finding indirect call type misma 781 for finding indirect call type mismatches during development.
875 782
876 If unsure, say N. 783 If unsure, say N.
877 784
878 config HAVE_ARCH_WITHIN_STACK_FRAMES 785 config HAVE_ARCH_WITHIN_STACK_FRAMES
879 bool 786 bool
880 help 787 help
881 An architecture should select this i 788 An architecture should select this if it can walk the kernel stack
882 frames to determine if an object is 789 frames to determine if an object is part of either the arguments
883 or local variables (i.e. that it exc 790 or local variables (i.e. that it excludes saved return addresses,
884 and similar) by implementing an inli 791 and similar) by implementing an inline arch_within_stack_frames(),
885 which is used by CONFIG_HARDENED_USE 792 which is used by CONFIG_HARDENED_USERCOPY.
886 793
887 config HAVE_CONTEXT_TRACKING_USER 794 config HAVE_CONTEXT_TRACKING_USER
888 bool 795 bool
889 help 796 help
890 Provide kernel/user boundaries probe 797 Provide kernel/user boundaries probes necessary for subsystems
891 that need it, such as userspace RCU 798 that need it, such as userspace RCU extended quiescent state.
892 Syscalls need to be wrapped inside u 799 Syscalls need to be wrapped inside user_exit()-user_enter(), either
893 optimized behind static key or throu 800 optimized behind static key or through the slow path using TIF_NOHZ
894 flag. Exceptions handlers must be wr 801 flag. Exceptions handlers must be wrapped as well. Irqs are already
895 protected inside ct_irq_enter/ct_irq 802 protected inside ct_irq_enter/ct_irq_exit() but preemption or signal
896 handling on irq exit still need to b 803 handling on irq exit still need to be protected.
897 804
898 config HAVE_CONTEXT_TRACKING_USER_OFFSTACK 805 config HAVE_CONTEXT_TRACKING_USER_OFFSTACK
899 bool 806 bool
900 help 807 help
901 Architecture neither relies on excep 808 Architecture neither relies on exception_enter()/exception_exit()
902 nor on schedule_user(). Also preempt 809 nor on schedule_user(). Also preempt_schedule_notrace() and
903 preempt_schedule_irq() can't be call 810 preempt_schedule_irq() can't be called in a preemptible section
904 while context tracking is CT_STATE_U !! 811 while context tracking is CONTEXT_USER. This feature reflects a sane
905 entry implementation where the follo 812 entry implementation where the following requirements are met on
906 critical entry code, ie: before user 813 critical entry code, ie: before user_exit() or after user_enter():
907 814
908 - Critical entry code isn't preempti 815 - Critical entry code isn't preemptible (or better yet:
909 not interruptible). 816 not interruptible).
910 - No use of RCU read side critical s 817 - No use of RCU read side critical sections, unless ct_nmi_enter()
911 got called. 818 got called.
912 - No use of instrumentation, unless 819 - No use of instrumentation, unless instrumentation_begin() got
913 called. 820 called.
914 821
915 config HAVE_TIF_NOHZ 822 config HAVE_TIF_NOHZ
916 bool 823 bool
917 help 824 help
918 Arch relies on TIF_NOHZ and syscall 825 Arch relies on TIF_NOHZ and syscall slow path to implement context
919 tracking calls to user_enter()/user_ 826 tracking calls to user_enter()/user_exit().
920 827
921 config HAVE_VIRT_CPU_ACCOUNTING 828 config HAVE_VIRT_CPU_ACCOUNTING
922 bool 829 bool
923 830
924 config HAVE_VIRT_CPU_ACCOUNTING_IDLE 831 config HAVE_VIRT_CPU_ACCOUNTING_IDLE
925 bool 832 bool
926 help 833 help
927 Architecture has its own way to acco 834 Architecture has its own way to account idle CPU time and therefore
928 doesn't implement vtime_account_idle 835 doesn't implement vtime_account_idle().
929 836
930 config ARCH_HAS_SCALED_CPUTIME 837 config ARCH_HAS_SCALED_CPUTIME
931 bool 838 bool
932 839
933 config HAVE_VIRT_CPU_ACCOUNTING_GEN 840 config HAVE_VIRT_CPU_ACCOUNTING_GEN
934 bool 841 bool
935 default y if 64BIT 842 default y if 64BIT
936 help 843 help
937 With VIRT_CPU_ACCOUNTING_GEN, cputim 844 With VIRT_CPU_ACCOUNTING_GEN, cputime_t becomes 64-bit.
938 Before enabling this option, arch co 845 Before enabling this option, arch code must be audited
939 to ensure there are no races in conc 846 to ensure there are no races in concurrent read/write of
940 cputime_t. For example, reading/writ 847 cputime_t. For example, reading/writing 64-bit cputime_t on
941 some 32-bit arches may require multi 848 some 32-bit arches may require multiple accesses, so proper
942 locking is needed to protect against 849 locking is needed to protect against concurrent accesses.
943 850
944 config HAVE_IRQ_TIME_ACCOUNTING 851 config HAVE_IRQ_TIME_ACCOUNTING
945 bool 852 bool
946 help 853 help
947 Archs need to ensure they use a high 854 Archs need to ensure they use a high enough resolution clock to
948 support irq time accounting and then 855 support irq time accounting and then call enable_sched_clock_irqtime().
949 856
950 config HAVE_MOVE_PUD 857 config HAVE_MOVE_PUD
951 bool 858 bool
952 help 859 help
953 Architectures that select this are a 860 Architectures that select this are able to move page tables at the
954 PUD level. If there are only 3 page 861 PUD level. If there are only 3 page table levels, the move effectively
955 happens at the PGD level. 862 happens at the PGD level.
956 863
957 config HAVE_MOVE_PMD 864 config HAVE_MOVE_PMD
958 bool 865 bool
959 help 866 help
960 Archs that select this are able to m 867 Archs that select this are able to move page tables at the PMD level.
961 868
962 config HAVE_ARCH_TRANSPARENT_HUGEPAGE 869 config HAVE_ARCH_TRANSPARENT_HUGEPAGE
963 bool 870 bool
964 871
965 config HAVE_ARCH_TRANSPARENT_HUGEPAGE_PUD 872 config HAVE_ARCH_TRANSPARENT_HUGEPAGE_PUD
966 bool 873 bool
967 874
968 config HAVE_ARCH_HUGE_VMAP 875 config HAVE_ARCH_HUGE_VMAP
969 bool 876 bool
970 877
971 # 878 #
972 # Archs that select this would be capable of 879 # Archs that select this would be capable of PMD-sized vmaps (i.e.,
973 # arch_vmap_pmd_supported() returns true). Th 880 # arch_vmap_pmd_supported() returns true). The VM_ALLOW_HUGE_VMAP flag
974 # must be used to enable allocations to use h 881 # must be used to enable allocations to use hugepages.
975 # 882 #
976 config HAVE_ARCH_HUGE_VMALLOC 883 config HAVE_ARCH_HUGE_VMALLOC
977 depends on HAVE_ARCH_HUGE_VMAP 884 depends on HAVE_ARCH_HUGE_VMAP
978 bool 885 bool
979 886
980 config ARCH_WANT_HUGE_PMD_SHARE 887 config ARCH_WANT_HUGE_PMD_SHARE
981 bool 888 bool
982 889
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 890 config HAVE_ARCH_SOFT_DIRTY
992 bool 891 bool
993 892
994 config HAVE_MOD_ARCH_SPECIFIC 893 config HAVE_MOD_ARCH_SPECIFIC
995 bool 894 bool
996 help 895 help
997 The arch uses struct mod_arch_specif 896 The arch uses struct mod_arch_specific to store data. Many arches
998 just need a simple module loader wit 897 just need a simple module loader without arch specific data - those
999 should not enable this. 898 should not enable this.
1000 899
1001 config MODULES_USE_ELF_RELA 900 config MODULES_USE_ELF_RELA
1002 bool 901 bool
1003 help 902 help
1004 Modules only use ELF RELA relocatio 903 Modules only use ELF RELA relocations. Modules with ELF REL
1005 relocations will give an error. 904 relocations will give an error.
1006 905
1007 config MODULES_USE_ELF_REL 906 config MODULES_USE_ELF_REL
1008 bool 907 bool
1009 help 908 help
1010 Modules only use ELF REL relocation 909 Modules only use ELF REL relocations. Modules with ELF RELA
1011 relocations will give an error. 910 relocations will give an error.
1012 911
1013 config ARCH_WANTS_MODULES_DATA_IN_VMALLOC 912 config ARCH_WANTS_MODULES_DATA_IN_VMALLOC
1014 bool 913 bool
1015 help 914 help
1016 For architectures like powerpc/32 w 915 For architectures like powerpc/32 which have constraints on module
1017 allocation and need to allocate mod 916 allocation and need to allocate module data outside of module area.
1018 917
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 918 config HAVE_IRQ_EXIT_ON_IRQ_STACK
1028 bool 919 bool
1029 help 920 help
1030 Architecture doesn't only execute t 921 Architecture doesn't only execute the irq handler on the irq stack
1031 but also irq_exit(). This way we ca 922 but also irq_exit(). This way we can process softirqs on this irq
1032 stack instead of switching to a new 923 stack instead of switching to a new one when we call __do_softirq()
1033 in the end of an hardirq. 924 in the end of an hardirq.
1034 This spares a stack switch and impr 925 This spares a stack switch and improves cache usage on softirq
1035 processing. 926 processing.
1036 927
1037 config HAVE_SOFTIRQ_ON_OWN_STACK 928 config HAVE_SOFTIRQ_ON_OWN_STACK
1038 bool 929 bool
1039 help 930 help
1040 Architecture provides a function to 931 Architecture provides a function to run __do_softirq() on a
1041 separate stack. 932 separate stack.
1042 933
1043 config SOFTIRQ_ON_OWN_STACK 934 config SOFTIRQ_ON_OWN_STACK
1044 def_bool HAVE_SOFTIRQ_ON_OWN_STACK && 935 def_bool HAVE_SOFTIRQ_ON_OWN_STACK && !PREEMPT_RT
1045 936
1046 config ALTERNATE_USER_ADDRESS_SPACE 937 config ALTERNATE_USER_ADDRESS_SPACE
1047 bool 938 bool
1048 help 939 help
1049 Architectures set this when the CPU 940 Architectures set this when the CPU uses separate address
1050 spaces for kernel and user space po 941 spaces for kernel and user space pointers. In this case, the
1051 access_ok() check on a __user point 942 access_ok() check on a __user pointer is skipped.
1052 943
1053 config PGTABLE_LEVELS 944 config PGTABLE_LEVELS
1054 int 945 int
1055 default 2 946 default 2
1056 947
1057 config ARCH_HAS_ELF_RANDOMIZE 948 config ARCH_HAS_ELF_RANDOMIZE
1058 bool 949 bool
1059 help 950 help
1060 An architecture supports choosing r 951 An architecture supports choosing randomized locations for
1061 stack, mmap, brk, and ET_DYN. Defin 952 stack, mmap, brk, and ET_DYN. Defined functions:
1062 - arch_mmap_rnd() 953 - arch_mmap_rnd()
1063 - arch_randomize_brk() 954 - arch_randomize_brk()
1064 955
1065 config HAVE_ARCH_MMAP_RND_BITS 956 config HAVE_ARCH_MMAP_RND_BITS
1066 bool 957 bool
1067 help 958 help
1068 An arch should select this symbol i 959 An arch should select this symbol if it supports setting a variable
1069 number of bits for use in establish 960 number of bits for use in establishing the base address for mmap
1070 allocations, has MMU enabled and pr 961 allocations, has MMU enabled and provides values for both:
1071 - ARCH_MMAP_RND_BITS_MIN 962 - ARCH_MMAP_RND_BITS_MIN
1072 - ARCH_MMAP_RND_BITS_MAX 963 - ARCH_MMAP_RND_BITS_MAX
1073 964
1074 config HAVE_EXIT_THREAD 965 config HAVE_EXIT_THREAD
1075 bool 966 bool
1076 help 967 help
1077 An architecture implements exit_thr 968 An architecture implements exit_thread.
1078 969
1079 config ARCH_MMAP_RND_BITS_MIN 970 config ARCH_MMAP_RND_BITS_MIN
1080 int 971 int
1081 972
1082 config ARCH_MMAP_RND_BITS_MAX 973 config ARCH_MMAP_RND_BITS_MAX
1083 int 974 int
1084 975
1085 config ARCH_MMAP_RND_BITS_DEFAULT 976 config ARCH_MMAP_RND_BITS_DEFAULT
1086 int 977 int
1087 978
1088 config ARCH_MMAP_RND_BITS 979 config ARCH_MMAP_RND_BITS
1089 int "Number of bits to use for ASLR o 980 int "Number of bits to use for ASLR of mmap base address" if EXPERT
1090 range ARCH_MMAP_RND_BITS_MIN ARCH_MMA 981 range ARCH_MMAP_RND_BITS_MIN ARCH_MMAP_RND_BITS_MAX
1091 default ARCH_MMAP_RND_BITS_DEFAULT if 982 default ARCH_MMAP_RND_BITS_DEFAULT if ARCH_MMAP_RND_BITS_DEFAULT
1092 default ARCH_MMAP_RND_BITS_MIN 983 default ARCH_MMAP_RND_BITS_MIN
1093 depends on HAVE_ARCH_MMAP_RND_BITS 984 depends on HAVE_ARCH_MMAP_RND_BITS
1094 help 985 help
1095 This value can be used to select th 986 This value can be used to select the number of bits to use to
1096 determine the random offset to the 987 determine the random offset to the base address of vma regions
1097 resulting from mmap allocations. Th 988 resulting from mmap allocations. This value will be bounded
1098 by the architecture's minimum and m 989 by the architecture's minimum and maximum supported values.
1099 990
1100 This value can be changed after boo 991 This value can be changed after boot using the
1101 /proc/sys/vm/mmap_rnd_bits tunable 992 /proc/sys/vm/mmap_rnd_bits tunable
1102 993
1103 config HAVE_ARCH_MMAP_RND_COMPAT_BITS 994 config HAVE_ARCH_MMAP_RND_COMPAT_BITS
1104 bool 995 bool
1105 help 996 help
1106 An arch should select this symbol i 997 An arch should select this symbol if it supports running applications
1107 in compatibility mode, supports set 998 in compatibility mode, supports setting a variable number of bits for
1108 use in establishing the base addres 999 use in establishing the base address for mmap allocations, has MMU
1109 enabled and provides values for bot 1000 enabled and provides values for both:
1110 - ARCH_MMAP_RND_COMPAT_BITS_MIN 1001 - ARCH_MMAP_RND_COMPAT_BITS_MIN
1111 - ARCH_MMAP_RND_COMPAT_BITS_MAX 1002 - ARCH_MMAP_RND_COMPAT_BITS_MAX
1112 1003
1113 config ARCH_MMAP_RND_COMPAT_BITS_MIN 1004 config ARCH_MMAP_RND_COMPAT_BITS_MIN
1114 int 1005 int
1115 1006
1116 config ARCH_MMAP_RND_COMPAT_BITS_MAX 1007 config ARCH_MMAP_RND_COMPAT_BITS_MAX
1117 int 1008 int
1118 1009
1119 config ARCH_MMAP_RND_COMPAT_BITS_DEFAULT 1010 config ARCH_MMAP_RND_COMPAT_BITS_DEFAULT
1120 int 1011 int
1121 1012
1122 config ARCH_MMAP_RND_COMPAT_BITS 1013 config ARCH_MMAP_RND_COMPAT_BITS
1123 int "Number of bits to use for ASLR o 1014 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 1015 range ARCH_MMAP_RND_COMPAT_BITS_MIN ARCH_MMAP_RND_COMPAT_BITS_MAX
1125 default ARCH_MMAP_RND_COMPAT_BITS_DEF 1016 default ARCH_MMAP_RND_COMPAT_BITS_DEFAULT if ARCH_MMAP_RND_COMPAT_BITS_DEFAULT
1126 default ARCH_MMAP_RND_COMPAT_BITS_MIN 1017 default ARCH_MMAP_RND_COMPAT_BITS_MIN
1127 depends on HAVE_ARCH_MMAP_RND_COMPAT_ 1018 depends on HAVE_ARCH_MMAP_RND_COMPAT_BITS
1128 help 1019 help
1129 This value can be used to select th 1020 This value can be used to select the number of bits to use to
1130 determine the random offset to the 1021 determine the random offset to the base address of vma regions
1131 resulting from mmap allocations for 1022 resulting from mmap allocations for compatible applications This
1132 value will be bounded by the archit 1023 value will be bounded by the architecture's minimum and maximum
1133 supported values. 1024 supported values.
1134 1025
1135 This value can be changed after boo 1026 This value can be changed after boot using the
1136 /proc/sys/vm/mmap_rnd_compat_bits t 1027 /proc/sys/vm/mmap_rnd_compat_bits tunable
1137 1028
1138 config HAVE_ARCH_COMPAT_MMAP_BASES 1029 config HAVE_ARCH_COMPAT_MMAP_BASES
1139 bool 1030 bool
1140 help 1031 help
1141 This allows 64bit applications to i 1032 This allows 64bit applications to invoke 32-bit mmap() syscall
1142 and vice-versa 32-bit applications 1033 and vice-versa 32-bit applications to call 64-bit mmap().
1143 Required for applications doing dif 1034 Required for applications doing different bitness syscalls.
1144 1035
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 1036 config PAGE_SIZE_LESS_THAN_64KB
1229 def_bool y 1037 def_bool y
>> 1038 depends on !ARM64_64K_PAGES
>> 1039 depends on !IA64_PAGE_SIZE_64KB
1230 depends on !PAGE_SIZE_64KB 1040 depends on !PAGE_SIZE_64KB
>> 1041 depends on !PARISC_PAGE_SIZE_64KB
1231 depends on PAGE_SIZE_LESS_THAN_256KB 1042 depends on PAGE_SIZE_LESS_THAN_256KB
1232 1043
1233 config PAGE_SIZE_LESS_THAN_256KB 1044 config PAGE_SIZE_LESS_THAN_256KB
1234 def_bool y 1045 def_bool y
1235 depends on !PAGE_SIZE_256KB 1046 depends on !PAGE_SIZE_256KB
1236 1047
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 1048 # This allows to use a set of generic functions to determine mmap base
1247 # address by giving priority to top-down sche 1049 # address by giving priority to top-down scheme only if the process
1248 # is not in legacy mode (compat task, unlimit 1050 # is not in legacy mode (compat task, unlimited stack size or
1249 # sysctl_legacy_va_layout). 1051 # sysctl_legacy_va_layout).
1250 # Architecture that selects this option can p 1052 # Architecture that selects this option can provide its own version of:
1251 # - STACK_RND_MASK 1053 # - STACK_RND_MASK
1252 config ARCH_WANT_DEFAULT_TOPDOWN_MMAP_LAYOUT 1054 config ARCH_WANT_DEFAULT_TOPDOWN_MMAP_LAYOUT
1253 bool 1055 bool
1254 depends on MMU 1056 depends on MMU
1255 select ARCH_HAS_ELF_RANDOMIZE 1057 select ARCH_HAS_ELF_RANDOMIZE
1256 1058
1257 config HAVE_OBJTOOL 1059 config HAVE_OBJTOOL
1258 bool 1060 bool
1259 1061
1260 config HAVE_JUMP_LABEL_HACK 1062 config HAVE_JUMP_LABEL_HACK
1261 bool 1063 bool
1262 1064
1263 config HAVE_NOINSTR_HACK 1065 config HAVE_NOINSTR_HACK
1264 bool 1066 bool
1265 1067
1266 config HAVE_NOINSTR_VALIDATION 1068 config HAVE_NOINSTR_VALIDATION
1267 bool 1069 bool
1268 1070
1269 config HAVE_UACCESS_VALIDATION 1071 config HAVE_UACCESS_VALIDATION
1270 bool 1072 bool
1271 select OBJTOOL 1073 select OBJTOOL
1272 1074
1273 config HAVE_STACK_VALIDATION 1075 config HAVE_STACK_VALIDATION
1274 bool 1076 bool
1275 help 1077 help
1276 Architecture supports objtool compi 1078 Architecture supports objtool compile-time frame pointer rule
1277 validation. 1079 validation.
1278 1080
1279 config HAVE_RELIABLE_STACKTRACE 1081 config HAVE_RELIABLE_STACKTRACE
1280 bool 1082 bool
1281 help 1083 help
1282 Architecture has either save_stack_ 1084 Architecture has either save_stack_trace_tsk_reliable() or
1283 arch_stack_walk_reliable() function 1085 arch_stack_walk_reliable() function which only returns a stack trace
1284 if it can guarantee the trace is re 1086 if it can guarantee the trace is reliable.
1285 1087
1286 config HAVE_ARCH_HASH 1088 config HAVE_ARCH_HASH
1287 bool 1089 bool
1288 default n 1090 default n
1289 help 1091 help
1290 If this is set, the architecture pr 1092 If this is set, the architecture provides an <asm/hash.h>
1291 file which provides platform-specif 1093 file which provides platform-specific implementations of some
1292 functions in <linux/hash.h> or fs/n 1094 functions in <linux/hash.h> or fs/namei.c.
1293 1095
1294 config HAVE_ARCH_NVRAM_OPS 1096 config HAVE_ARCH_NVRAM_OPS
1295 bool 1097 bool
1296 1098
1297 config ISA_BUS_API 1099 config ISA_BUS_API
1298 def_bool ISA 1100 def_bool ISA
1299 1101
1300 # 1102 #
1301 # ABI hall of shame 1103 # ABI hall of shame
1302 # 1104 #
1303 config CLONE_BACKWARDS 1105 config CLONE_BACKWARDS
1304 bool 1106 bool
1305 help 1107 help
1306 Architecture has tls passed as the 1108 Architecture has tls passed as the 4th argument of clone(2),
1307 not the 5th one. 1109 not the 5th one.
1308 1110
1309 config CLONE_BACKWARDS2 1111 config CLONE_BACKWARDS2
1310 bool 1112 bool
1311 help 1113 help
1312 Architecture has the first two argu 1114 Architecture has the first two arguments of clone(2) swapped.
1313 1115
1314 config CLONE_BACKWARDS3 1116 config CLONE_BACKWARDS3
1315 bool 1117 bool
1316 help 1118 help
1317 Architecture has tls passed as the 1119 Architecture has tls passed as the 3rd argument of clone(2),
1318 not the 5th one. 1120 not the 5th one.
1319 1121
1320 config ODD_RT_SIGACTION 1122 config ODD_RT_SIGACTION
1321 bool 1123 bool
1322 help 1124 help
1323 Architecture has unusual rt_sigacti 1125 Architecture has unusual rt_sigaction(2) arguments
1324 1126
1325 config OLD_SIGSUSPEND 1127 config OLD_SIGSUSPEND
1326 bool 1128 bool
1327 help 1129 help
1328 Architecture has old sigsuspend(2) 1130 Architecture has old sigsuspend(2) syscall, of one-argument variety
1329 1131
1330 config OLD_SIGSUSPEND3 1132 config OLD_SIGSUSPEND3
1331 bool 1133 bool
1332 help 1134 help
1333 Even weirder antique ABI - three-ar 1135 Even weirder antique ABI - three-argument sigsuspend(2)
1334 1136
1335 config OLD_SIGACTION 1137 config OLD_SIGACTION
1336 bool 1138 bool
1337 help 1139 help
1338 Architecture has old sigaction(2) s 1140 Architecture has old sigaction(2) syscall. Nope, not the same
1339 as OLD_SIGSUSPEND | OLD_SIGSUSPEND3 1141 as OLD_SIGSUSPEND | OLD_SIGSUSPEND3 - alpha has sigsuspend(2),
1340 but fairly different variant of sig 1142 but fairly different variant of sigaction(2), thanks to OSF/1
1341 compatibility... 1143 compatibility...
1342 1144
1343 config COMPAT_OLD_SIGACTION 1145 config COMPAT_OLD_SIGACTION
1344 bool 1146 bool
1345 1147
1346 config COMPAT_32BIT_TIME 1148 config COMPAT_32BIT_TIME
1347 bool "Provide system calls for 32-bit 1149 bool "Provide system calls for 32-bit time_t"
1348 default !64BIT || COMPAT 1150 default !64BIT || COMPAT
1349 help 1151 help
1350 This enables 32 bit time_t support 1152 This enables 32 bit time_t support in addition to 64 bit time_t support.
1351 This is relevant on all 32-bit arch 1153 This is relevant on all 32-bit architectures, and 64-bit architectures
1352 as part of compat syscall handling. 1154 as part of compat syscall handling.
1353 1155
1354 config ARCH_NO_PREEMPT 1156 config ARCH_NO_PREEMPT
1355 bool 1157 bool
1356 1158
>> 1159 config ARCH_EPHEMERAL_INODES
>> 1160 def_bool n
>> 1161 help
>> 1162 An arch should select this symbol if it doesn't keep track of inode
>> 1163 instances on its own, but instead relies on something else (e.g. the
>> 1164 host kernel for an UML kernel).
>> 1165
1357 config ARCH_SUPPORTS_RT 1166 config ARCH_SUPPORTS_RT
1358 bool 1167 bool
1359 1168
1360 config CPU_NO_EFFICIENT_FFS 1169 config CPU_NO_EFFICIENT_FFS
1361 def_bool n 1170 def_bool n
1362 1171
1363 config HAVE_ARCH_VMAP_STACK 1172 config HAVE_ARCH_VMAP_STACK
1364 def_bool n 1173 def_bool n
1365 help 1174 help
1366 An arch should select this symbol i 1175 An arch should select this symbol if it can support kernel stacks
1367 in vmalloc space. This means: 1176 in vmalloc space. This means:
1368 1177
1369 - vmalloc space must be large enoug 1178 - vmalloc space must be large enough to hold many kernel stacks.
1370 This may rule out many 32-bit arc 1179 This may rule out many 32-bit architectures.
1371 1180
1372 - Stacks in vmalloc space need to w 1181 - Stacks in vmalloc space need to work reliably. For example, if
1373 vmap page tables are created on d 1182 vmap page tables are created on demand, either this mechanism
1374 needs to work while the stack poi 1183 needs to work while the stack points to a virtual address with
1375 unpopulated page tables or arch c 1184 unpopulated page tables or arch code (switch_to() and switch_mm(),
1376 most likely) needs to ensure that 1185 most likely) needs to ensure that the stack's page table entries
1377 are populated before running on a 1186 are populated before running on a possibly unpopulated stack.
1378 1187
1379 - If the stack overflows into a gua 1188 - If the stack overflows into a guard page, something reasonable
1380 should happen. The definition of 1189 should happen. The definition of "reasonable" is flexible, but
1381 instantly rebooting without loggi 1190 instantly rebooting without logging anything would be unfriendly.
1382 1191
1383 config VMAP_STACK 1192 config VMAP_STACK
1384 default y 1193 default y
1385 bool "Use a virtually-mapped stack" 1194 bool "Use a virtually-mapped stack"
1386 depends on HAVE_ARCH_VMAP_STACK 1195 depends on HAVE_ARCH_VMAP_STACK
1387 depends on !KASAN || KASAN_HW_TAGS || 1196 depends on !KASAN || KASAN_HW_TAGS || KASAN_VMALLOC
1388 help 1197 help
1389 Enable this if you want the use vir 1198 Enable this if you want the use virtually-mapped kernel stacks
1390 with guard pages. This causes kern 1199 with guard pages. This causes kernel stack overflows to be
1391 caught immediately rather than caus 1200 caught immediately rather than causing difficult-to-diagnose
1392 corruption. 1201 corruption.
1393 1202
1394 To use this with software KASAN mod 1203 To use this with software KASAN modes, the architecture must support
1395 backing virtual mappings with real 1204 backing virtual mappings with real shadow memory, and KASAN_VMALLOC
1396 must be enabled. 1205 must be enabled.
1397 1206
1398 config HAVE_ARCH_RANDOMIZE_KSTACK_OFFSET 1207 config HAVE_ARCH_RANDOMIZE_KSTACK_OFFSET
1399 def_bool n 1208 def_bool n
1400 help 1209 help
1401 An arch should select this symbol i 1210 An arch should select this symbol if it can support kernel stack
1402 offset randomization with calls to 1211 offset randomization with calls to add_random_kstack_offset()
1403 during syscall entry and choose_ran 1212 during syscall entry and choose_random_kstack_offset() during
1404 syscall exit. Careful removal of -f 1213 syscall exit. Careful removal of -fstack-protector-strong and
1405 -fstack-protector should also be ap 1214 -fstack-protector should also be applied to the entry code and
1406 closely examined, as the artificial 1215 closely examined, as the artificial stack bump looks like an array
1407 to the compiler, so it will attempt 1216 to the compiler, so it will attempt to add canary checks regardless
1408 of the static branch state. 1217 of the static branch state.
1409 1218
1410 config RANDOMIZE_KSTACK_OFFSET 1219 config RANDOMIZE_KSTACK_OFFSET
1411 bool "Support for randomizing kernel 1220 bool "Support for randomizing kernel stack offset on syscall entry" if EXPERT
1412 default y 1221 default y
1413 depends on HAVE_ARCH_RANDOMIZE_KSTACK 1222 depends on HAVE_ARCH_RANDOMIZE_KSTACK_OFFSET
1414 depends on INIT_STACK_NONE || !CC_IS_ 1223 depends on INIT_STACK_NONE || !CC_IS_CLANG || CLANG_VERSION >= 140000
1415 help 1224 help
1416 The kernel stack offset can be rand 1225 The kernel stack offset can be randomized (after pt_regs) by
1417 roughly 5 bits of entropy, frustrat 1226 roughly 5 bits of entropy, frustrating memory corruption
1418 attacks that depend on stack addres 1227 attacks that depend on stack address determinism or
1419 cross-syscall address exposures. 1228 cross-syscall address exposures.
1420 1229
1421 The feature is controlled via the " 1230 The feature is controlled via the "randomize_kstack_offset=on/off"
1422 kernel boot param, and if turned of 1231 kernel boot param, and if turned off has zero overhead due to its use
1423 of static branches (see JUMP_LABEL) 1232 of static branches (see JUMP_LABEL).
1424 1233
1425 If unsure, say Y. 1234 If unsure, say Y.
1426 1235
1427 config RANDOMIZE_KSTACK_OFFSET_DEFAULT 1236 config RANDOMIZE_KSTACK_OFFSET_DEFAULT
1428 bool "Default state of kernel stack o 1237 bool "Default state of kernel stack offset randomization"
1429 depends on RANDOMIZE_KSTACK_OFFSET 1238 depends on RANDOMIZE_KSTACK_OFFSET
1430 help 1239 help
1431 Kernel stack offset randomization i 1240 Kernel stack offset randomization is controlled by kernel boot param
1432 "randomize_kstack_offset=on/off", a 1241 "randomize_kstack_offset=on/off", and this config chooses the default
1433 boot state. 1242 boot state.
1434 1243
1435 config ARCH_OPTIONAL_KERNEL_RWX 1244 config ARCH_OPTIONAL_KERNEL_RWX
1436 def_bool n 1245 def_bool n
1437 1246
1438 config ARCH_OPTIONAL_KERNEL_RWX_DEFAULT 1247 config ARCH_OPTIONAL_KERNEL_RWX_DEFAULT
1439 def_bool n 1248 def_bool n
1440 1249
1441 config ARCH_HAS_STRICT_KERNEL_RWX 1250 config ARCH_HAS_STRICT_KERNEL_RWX
1442 def_bool n 1251 def_bool n
1443 1252
1444 config STRICT_KERNEL_RWX 1253 config STRICT_KERNEL_RWX
1445 bool "Make kernel text and rodata rea 1254 bool "Make kernel text and rodata read-only" if ARCH_OPTIONAL_KERNEL_RWX
1446 depends on ARCH_HAS_STRICT_KERNEL_RWX 1255 depends on ARCH_HAS_STRICT_KERNEL_RWX
1447 default !ARCH_OPTIONAL_KERNEL_RWX || 1256 default !ARCH_OPTIONAL_KERNEL_RWX || ARCH_OPTIONAL_KERNEL_RWX_DEFAULT
1448 help 1257 help
1449 If this is set, kernel text and rod 1258 If this is set, kernel text and rodata memory will be made read-only,
1450 and non-text memory will be made no 1259 and non-text memory will be made non-executable. This provides
1451 protection against certain security 1260 protection against certain security exploits (e.g. executing the heap
1452 or modifying text) 1261 or modifying text)
1453 1262
1454 These features are considered stand 1263 These features are considered standard security practice these days.
1455 You should say Y here in almost all 1264 You should say Y here in almost all cases.
1456 1265
1457 config ARCH_HAS_STRICT_MODULE_RWX 1266 config ARCH_HAS_STRICT_MODULE_RWX
1458 def_bool n 1267 def_bool n
1459 1268
1460 config STRICT_MODULE_RWX 1269 config STRICT_MODULE_RWX
1461 bool "Set loadable kernel module data 1270 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 1271 depends on ARCH_HAS_STRICT_MODULE_RWX && MODULES
1463 default !ARCH_OPTIONAL_KERNEL_RWX || 1272 default !ARCH_OPTIONAL_KERNEL_RWX || ARCH_OPTIONAL_KERNEL_RWX_DEFAULT
1464 help 1273 help
1465 If this is set, module text and rod 1274 If this is set, module text and rodata memory will be made read-only,
1466 and non-text memory will be made no 1275 and non-text memory will be made non-executable. This provides
1467 protection against certain security 1276 protection against certain security exploits (e.g. writing to text)
1468 1277
1469 # select if the architecture provides an asm/ 1278 # select if the architecture provides an asm/dma-direct.h header
1470 config ARCH_HAS_PHYS_TO_DMA 1279 config ARCH_HAS_PHYS_TO_DMA
1471 bool 1280 bool
1472 1281
1473 config HAVE_ARCH_COMPILER_H 1282 config HAVE_ARCH_COMPILER_H
1474 bool 1283 bool
1475 help 1284 help
1476 An architecture can select this if 1285 An architecture can select this if it provides an
1477 asm/compiler.h header that should b 1286 asm/compiler.h header that should be included after
1478 linux/compiler-*.h in order to over 1287 linux/compiler-*.h in order to override macro definitions that those
1479 headers generally provide. 1288 headers generally provide.
1480 1289
1481 config HAVE_ARCH_PREL32_RELOCATIONS 1290 config HAVE_ARCH_PREL32_RELOCATIONS
1482 bool 1291 bool
1483 help 1292 help
1484 May be selected by an architecture 1293 May be selected by an architecture if it supports place-relative
1485 32-bit relocations, both in the too 1294 32-bit relocations, both in the toolchain and in the module loader,
1486 in which case relative references c 1295 in which case relative references can be used in special sections
1487 for PCI fixup, initcalls etc which 1296 for PCI fixup, initcalls etc which are only half the size on 64 bit
1488 architectures, and don't require ru 1297 architectures, and don't require runtime relocation on relocatable
1489 kernels. 1298 kernels.
1490 1299
1491 config ARCH_USE_MEMREMAP_PROT 1300 config ARCH_USE_MEMREMAP_PROT
1492 bool 1301 bool
1493 1302
1494 config LOCK_EVENT_COUNTS 1303 config LOCK_EVENT_COUNTS
1495 bool "Locking event counts collection 1304 bool "Locking event counts collection"
1496 depends on DEBUG_FS 1305 depends on DEBUG_FS
1497 help 1306 help
1498 Enable light-weight counting of var 1307 Enable light-weight counting of various locking related events
1499 in the system with minimal performa 1308 in the system with minimal performance impact. This reduces
1500 the chance of application behavior 1309 the chance of application behavior change because of timing
1501 differences. The counts are reporte 1310 differences. The counts are reported via debugfs.
1502 1311
1503 # Select if the architecture has support for 1312 # Select if the architecture has support for applying RELR relocations.
1504 config ARCH_HAS_RELR 1313 config ARCH_HAS_RELR
1505 bool 1314 bool
1506 1315
1507 config RELR 1316 config RELR
1508 bool "Use RELR relocation packing" 1317 bool "Use RELR relocation packing"
1509 depends on ARCH_HAS_RELR && TOOLS_SUP 1318 depends on ARCH_HAS_RELR && TOOLS_SUPPORT_RELR
1510 default y 1319 default y
1511 help 1320 help
1512 Store the kernel's dynamic relocati 1321 Store the kernel's dynamic relocations in the RELR relocation packing
1513 format. Requires a compatible linke 1322 format. Requires a compatible linker (LLD supports this feature), as
1514 well as compatible NM and OBJCOPY u 1323 well as compatible NM and OBJCOPY utilities (llvm-nm and llvm-objcopy
1515 are compatible). 1324 are compatible).
1516 1325
1517 config ARCH_HAS_MEM_ENCRYPT 1326 config ARCH_HAS_MEM_ENCRYPT
1518 bool 1327 bool
1519 1328
1520 config ARCH_HAS_CC_PLATFORM 1329 config ARCH_HAS_CC_PLATFORM
1521 bool 1330 bool
1522 1331
1523 config HAVE_SPARSE_SYSCALL_NR 1332 config HAVE_SPARSE_SYSCALL_NR
1524 bool !! 1333 bool
1525 help !! 1334 help
1526 An architecture should select this !! 1335 An architecture should select this if its syscall numbering is sparse
1527 to save space. For example, MIPS ar 1336 to save space. For example, MIPS architecture has a syscall array with
1528 entries at 4000, 5000 and 6000 loca 1337 entries at 4000, 5000 and 6000 locations. This option turns on syscall
1529 related optimizations for a given a 1338 related optimizations for a given architecture.
1530 1339
1531 config ARCH_HAS_VDSO_DATA 1340 config ARCH_HAS_VDSO_DATA
1532 bool 1341 bool
1533 1342
1534 config HAVE_STATIC_CALL 1343 config HAVE_STATIC_CALL
1535 bool 1344 bool
1536 1345
1537 config HAVE_STATIC_CALL_INLINE 1346 config HAVE_STATIC_CALL_INLINE
1538 bool 1347 bool
1539 depends on HAVE_STATIC_CALL 1348 depends on HAVE_STATIC_CALL
1540 select OBJTOOL 1349 select OBJTOOL
1541 1350
1542 config HAVE_PREEMPT_DYNAMIC 1351 config HAVE_PREEMPT_DYNAMIC
1543 bool 1352 bool
1544 1353
1545 config HAVE_PREEMPT_DYNAMIC_CALL 1354 config HAVE_PREEMPT_DYNAMIC_CALL
1546 bool 1355 bool
1547 depends on HAVE_STATIC_CALL 1356 depends on HAVE_STATIC_CALL
1548 select HAVE_PREEMPT_DYNAMIC 1357 select HAVE_PREEMPT_DYNAMIC
1549 help 1358 help
1550 An architecture should select this !! 1359 An architecture should select this if it can handle the preemption
1551 model being selected at boot time u !! 1360 model being selected at boot time using static calls.
1552 1361
1553 Where an architecture selects HAVE_ !! 1362 Where an architecture selects HAVE_STATIC_CALL_INLINE, any call to a
1554 preemption function will be patched !! 1363 preemption function will be patched directly.
1555 1364
1556 Where an architecture does not sele !! 1365 Where an architecture does not select HAVE_STATIC_CALL_INLINE, any
1557 call to a preemption function will !! 1366 call to a preemption function will go through a trampoline, and the
1558 trampoline will be patched. !! 1367 trampoline will be patched.
1559 1368
1560 It is strongly advised to support i !! 1369 It is strongly advised to support inline static call to avoid any
1561 overhead. !! 1370 overhead.
1562 1371
1563 config HAVE_PREEMPT_DYNAMIC_KEY 1372 config HAVE_PREEMPT_DYNAMIC_KEY
1564 bool 1373 bool
1565 depends on HAVE_ARCH_JUMP_LABEL 1374 depends on HAVE_ARCH_JUMP_LABEL
1566 select HAVE_PREEMPT_DYNAMIC 1375 select HAVE_PREEMPT_DYNAMIC
1567 help 1376 help
1568 An architecture should select this !! 1377 An architecture should select this if it can handle the preemption
1569 model being selected at boot time u !! 1378 model being selected at boot time using static keys.
1570 1379
1571 Each preemption function will be gi !! 1380 Each preemption function will be given an early return based on a
1572 static key. This should have slight !! 1381 static key. This should have slightly lower overhead than non-inline
1573 static calls, as this effectively i !! 1382 static calls, as this effectively inlines each trampoline into the
1574 start of its callee. This may avoid !! 1383 start of its callee. This may avoid redundant work, and may
1575 integrate better with CFI schemes. !! 1384 integrate better with CFI schemes.
1576 1385
1577 This will have greater overhead tha !! 1386 This will have greater overhead than using inline static calls as
1578 the call to the preemption function !! 1387 the call to the preemption function cannot be entirely elided.
1579 1388
1580 config ARCH_WANT_LD_ORPHAN_WARN 1389 config ARCH_WANT_LD_ORPHAN_WARN
1581 bool 1390 bool
1582 help 1391 help
1583 An arch should select this symbol o 1392 An arch should select this symbol once all linker sections are explicitly
1584 included, size-asserted, or discard 1393 included, size-asserted, or discarded in the linker scripts. This is
1585 important because we never want exp 1394 important because we never want expected sections to be placed heuristically
1586 by the linker, since the locations 1395 by the linker, since the locations of such sections can change between linker
1587 versions. 1396 versions.
1588 1397
1589 config HAVE_ARCH_PFN_VALID 1398 config HAVE_ARCH_PFN_VALID
1590 bool 1399 bool
1591 1400
1592 config ARCH_SUPPORTS_DEBUG_PAGEALLOC 1401 config ARCH_SUPPORTS_DEBUG_PAGEALLOC
1593 bool 1402 bool
1594 1403
1595 config ARCH_SUPPORTS_PAGE_TABLE_CHECK 1404 config ARCH_SUPPORTS_PAGE_TABLE_CHECK
1596 bool 1405 bool
1597 1406
1598 config ARCH_SPLIT_ARG64 1407 config ARCH_SPLIT_ARG64
1599 bool 1408 bool
1600 help 1409 help
1601 If a 32-bit architecture requires 6 !! 1410 If a 32-bit architecture requires 64-bit arguments to be split into
1602 pairs of 32-bit arguments, select t !! 1411 pairs of 32-bit arguments, select this option.
1603 1412
1604 config ARCH_HAS_ELFCORE_COMPAT 1413 config ARCH_HAS_ELFCORE_COMPAT
1605 bool 1414 bool
1606 1415
1607 config ARCH_HAS_PARANOID_L1D_FLUSH 1416 config ARCH_HAS_PARANOID_L1D_FLUSH
1608 bool 1417 bool
1609 1418
1610 config ARCH_HAVE_TRACE_MMIO_ACCESS 1419 config ARCH_HAVE_TRACE_MMIO_ACCESS
1611 bool 1420 bool
1612 1421
1613 config DYNAMIC_SIGFRAME 1422 config DYNAMIC_SIGFRAME
1614 bool 1423 bool
1615 1424
1616 # Select, if arch has a named attribute group 1425 # Select, if arch has a named attribute group bound to NUMA device nodes.
1617 config HAVE_ARCH_NODE_DEV_GROUP 1426 config HAVE_ARCH_NODE_DEV_GROUP
1618 bool 1427 bool
1619 1428
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 1429 config ARCH_HAS_NONLEAF_PMD_YOUNG
1629 bool 1430 bool
1630 help 1431 help
1631 Architectures that select this opti 1432 Architectures that select this option are capable of setting the
1632 accessed bit in non-leaf PMD entrie 1433 accessed bit in non-leaf PMD entries when using them as part of linear
1633 address translations. Page table wa 1434 address translations. Page table walkers that clear the accessed bit
1634 may use this capability to reduce t 1435 may use this capability to reduce their search space.
1635 1436
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" 1437 source "kernel/gcov/Kconfig"
1643 1438
1644 source "scripts/gcc-plugins/Kconfig" 1439 source "scripts/gcc-plugins/Kconfig"
1645 1440
1646 config FUNCTION_ALIGNMENT_4B 1441 config FUNCTION_ALIGNMENT_4B
1647 bool 1442 bool
1648 1443
1649 config FUNCTION_ALIGNMENT_8B 1444 config FUNCTION_ALIGNMENT_8B
1650 bool 1445 bool
1651 1446
1652 config FUNCTION_ALIGNMENT_16B 1447 config FUNCTION_ALIGNMENT_16B
1653 bool 1448 bool
1654 1449
1655 config FUNCTION_ALIGNMENT_32B 1450 config FUNCTION_ALIGNMENT_32B
1656 bool 1451 bool
1657 1452
1658 config FUNCTION_ALIGNMENT_64B 1453 config FUNCTION_ALIGNMENT_64B
1659 bool 1454 bool
1660 1455
1661 config FUNCTION_ALIGNMENT 1456 config FUNCTION_ALIGNMENT
1662 int 1457 int
1663 default 64 if FUNCTION_ALIGNMENT_64B 1458 default 64 if FUNCTION_ALIGNMENT_64B
1664 default 32 if FUNCTION_ALIGNMENT_32B 1459 default 32 if FUNCTION_ALIGNMENT_32B
1665 default 16 if FUNCTION_ALIGNMENT_16B 1460 default 16 if FUNCTION_ALIGNMENT_16B
1666 default 8 if FUNCTION_ALIGNMENT_8B 1461 default 8 if FUNCTION_ALIGNMENT_8B
1667 default 4 if FUNCTION_ALIGNMENT_4B 1462 default 4 if FUNCTION_ALIGNMENT_4B
1668 default 0 1463 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 1464
1685 endmenu 1465 endmenu
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