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