1 # SPDX-License-Identifier: GPL-2.0 1 # SPDX-License-Identifier: GPL-2.0
2 # 2 #
3 # General architecture dependent options 3 # General architecture dependent options
4 # 4 #
5 5
6 # 6 #
7 # Note: arch/$(SRCARCH)/Kconfig needs to be in 7 # Note: arch/$(SRCARCH)/Kconfig needs to be included first so that it can
8 # override the default values in this file. 8 # override the default values in this file.
9 # 9 #
10 source "arch/$(SRCARCH)/Kconfig" 10 source "arch/$(SRCARCH)/Kconfig"
11 11
12 config ARCH_CONFIGURES_CPU_MITIGATIONS <<
13 bool <<
14 <<
15 if !ARCH_CONFIGURES_CPU_MITIGATIONS <<
16 config CPU_MITIGATIONS <<
17 def_bool y <<
18 endif <<
19 <<
20 menu "General architecture-dependent options" 12 menu "General architecture-dependent options"
21 13
22 config ARCH_HAS_SUBPAGE_FAULTS !! 14 config CRASH_CORE
23 bool <<
24 help <<
25 Select if the architecture can check <<
26 granularity (e.g. arm64 MTE). The pr <<
27 must be implemented. <<
28 <<
29 config HOTPLUG_SMT <<
30 bool <<
31 <<
32 config SMT_NUM_THREADS_DYNAMIC <<
33 bool 15 bool
34 16
35 # Selected by HOTPLUG_CORE_SYNC_DEAD or HOTPLU !! 17 config KEXEC_CORE
36 config HOTPLUG_CORE_SYNC !! 18 select CRASH_CORE
37 bool 19 bool
38 20
39 # Basic CPU dead synchronization selected by a !! 21 config KEXEC_ELF
40 config HOTPLUG_CORE_SYNC_DEAD <<
41 bool 22 bool
42 select HOTPLUG_CORE_SYNC <<
43 23
44 # Full CPU synchronization with alive state se !! 24 config HAVE_IMA_KEXEC
45 config HOTPLUG_CORE_SYNC_FULL <<
46 bool 25 bool
47 select HOTPLUG_CORE_SYNC_DEAD if HOTPL <<
48 select HOTPLUG_CORE_SYNC <<
49 26
50 config HOTPLUG_SPLIT_STARTUP !! 27 config ARCH_HAS_SUBPAGE_FAULTS
51 bool 28 bool
52 select HOTPLUG_CORE_SYNC_FULL !! 29 help
>> 30 Select if the architecture can check permissions at sub-page
>> 31 granularity (e.g. arm64 MTE). The probe_user_*() functions
>> 32 must be implemented.
53 33
54 config HOTPLUG_PARALLEL !! 34 config HOTPLUG_SMT
55 bool 35 bool
56 select HOTPLUG_SPLIT_STARTUP <<
57 36
58 config GENERIC_ENTRY 37 config GENERIC_ENTRY
59 bool !! 38 bool
60 39
61 config KPROBES 40 config KPROBES
62 bool "Kprobes" 41 bool "Kprobes"
>> 42 depends on MODULES
63 depends on HAVE_KPROBES 43 depends on HAVE_KPROBES
64 select KALLSYMS 44 select KALLSYMS
65 select EXECMEM !! 45 select TASKS_RCU if PREEMPTION
66 select NEED_TASKS_RCU <<
67 help 46 help
68 Kprobes allows you to trap at almost 47 Kprobes allows you to trap at almost any kernel address and
69 execute a callback function. regist 48 execute a callback function. register_kprobe() establishes
70 a probepoint and specifies the callb 49 a probepoint and specifies the callback. Kprobes is useful
71 for kernel debugging, non-intrusive 50 for kernel debugging, non-intrusive instrumentation and testing.
72 If in doubt, say "N". 51 If in doubt, say "N".
73 52
74 config JUMP_LABEL 53 config JUMP_LABEL
75 bool "Optimize very unlikely/likely br 54 bool "Optimize very unlikely/likely branches"
76 depends on HAVE_ARCH_JUMP_LABEL 55 depends on HAVE_ARCH_JUMP_LABEL
>> 56 depends on CC_HAS_ASM_GOTO
77 select OBJTOOL if HAVE_JUMP_LABEL_HACK 57 select OBJTOOL if HAVE_JUMP_LABEL_HACK
78 help 58 help
79 This option enables a transparent br !! 59 This option enables a transparent branch optimization that
80 makes certain almost-always-true or !! 60 makes certain almost-always-true or almost-always-false branch
81 conditions even cheaper to execute w !! 61 conditions even cheaper to execute within the kernel.
82 !! 62
83 Certain performance-sensitive kernel !! 63 Certain performance-sensitive kernel code, such as trace points,
84 scheduler functionality, networking !! 64 scheduler functionality, networking code and KVM have such
85 branches and include support for thi !! 65 branches and include support for this optimization technique.
86 !! 66
87 If it is detected that the compiler !! 67 If it is detected that the compiler has support for "asm goto",
88 the kernel will compile such branche !! 68 the kernel will compile such branches with just a nop
89 instruction. When the condition flag !! 69 instruction. When the condition flag is toggled to true, the
90 nop will be converted to a jump inst !! 70 nop will be converted to a jump instruction to execute the
91 conditional block of instructions. !! 71 conditional block of instructions.
92 !! 72
93 This technique lowers overhead and s !! 73 This technique lowers overhead and stress on the branch prediction
94 of the processor and generally makes !! 74 of the processor and generally makes the kernel faster. The update
95 of the condition is slower, but thos !! 75 of the condition is slower, but those are always very rare.
96 76
97 ( On 32-bit x86, the necessary optio !! 77 ( On 32-bit x86, the necessary options added to the compiler
98 flags may increase the size of the !! 78 flags may increase the size of the kernel slightly. )
99 79
100 config STATIC_KEYS_SELFTEST 80 config STATIC_KEYS_SELFTEST
101 bool "Static key selftest" 81 bool "Static key selftest"
102 depends on JUMP_LABEL 82 depends on JUMP_LABEL
103 help 83 help
104 Boot time self-test of the branch pa 84 Boot time self-test of the branch patching code.
105 85
106 config STATIC_CALL_SELFTEST 86 config STATIC_CALL_SELFTEST
107 bool "Static call selftest" 87 bool "Static call selftest"
108 depends on HAVE_STATIC_CALL 88 depends on HAVE_STATIC_CALL
109 help 89 help
110 Boot time self-test of the call patc 90 Boot time self-test of the call patching code.
111 91
112 config OPTPROBES 92 config OPTPROBES
113 def_bool y 93 def_bool y
114 depends on KPROBES && HAVE_OPTPROBES 94 depends on KPROBES && HAVE_OPTPROBES
115 select NEED_TASKS_RCU !! 95 select TASKS_RCU if PREEMPTION
116 96
117 config KPROBES_ON_FTRACE 97 config KPROBES_ON_FTRACE
118 def_bool y 98 def_bool y
119 depends on KPROBES && HAVE_KPROBES_ON_ 99 depends on KPROBES && HAVE_KPROBES_ON_FTRACE
120 depends on DYNAMIC_FTRACE_WITH_REGS 100 depends on DYNAMIC_FTRACE_WITH_REGS
121 help 101 help
122 If function tracer is enabled and th !! 102 If function tracer is enabled and the arch supports full
123 passing of pt_regs to function traci !! 103 passing of pt_regs to function tracing, then kprobes can
124 optimize on top of function tracing. !! 104 optimize on top of function tracing.
125 105
126 config UPROBES 106 config UPROBES
127 def_bool n 107 def_bool n
128 depends on ARCH_SUPPORTS_UPROBES 108 depends on ARCH_SUPPORTS_UPROBES
129 help 109 help
130 Uprobes is the user-space counterpar 110 Uprobes is the user-space counterpart to kprobes: they
131 enable instrumentation applications 111 enable instrumentation applications (such as 'perf probe')
132 to establish unintrusive probes in u 112 to establish unintrusive probes in user-space binaries and
133 libraries, by executing handler func 113 libraries, by executing handler functions when the probes
134 are hit by user-space applications. 114 are hit by user-space applications.
135 115
136 ( These probes come in the form of s 116 ( These probes come in the form of single-byte breakpoints,
137 managed by the kernel and kept tra 117 managed by the kernel and kept transparent to the probed
138 application. ) 118 application. )
139 119
140 config HAVE_64BIT_ALIGNED_ACCESS 120 config HAVE_64BIT_ALIGNED_ACCESS
141 def_bool 64BIT && !HAVE_EFFICIENT_UNAL 121 def_bool 64BIT && !HAVE_EFFICIENT_UNALIGNED_ACCESS
142 help 122 help
143 Some architectures require 64 bit ac 123 Some architectures require 64 bit accesses to be 64 bit
144 aligned, which also requires structs 124 aligned, which also requires structs containing 64 bit values
145 to be 64 bit aligned too. This inclu 125 to be 64 bit aligned too. This includes some 32 bit
146 architectures which can do 64 bit ac 126 architectures which can do 64 bit accesses, as well as 64 bit
147 architectures without unaligned acce 127 architectures without unaligned access.
148 128
149 This symbol should be selected by an 129 This symbol should be selected by an architecture if 64 bit
150 accesses are required to be 64 bit a 130 accesses are required to be 64 bit aligned in this way even
151 though it is not a 64 bit architectu 131 though it is not a 64 bit architecture.
152 132
153 See Documentation/core-api/unaligned 133 See Documentation/core-api/unaligned-memory-access.rst for
154 more information on the topic of una 134 more information on the topic of unaligned memory accesses.
155 135
156 config HAVE_EFFICIENT_UNALIGNED_ACCESS 136 config HAVE_EFFICIENT_UNALIGNED_ACCESS
157 bool 137 bool
158 help 138 help
159 Some architectures are unable to per 139 Some architectures are unable to perform unaligned accesses
160 without the use of get_unaligned/put 140 without the use of get_unaligned/put_unaligned. Others are
161 unable to perform such accesses effi 141 unable to perform such accesses efficiently (e.g. trap on
162 unaligned access and require fixing 142 unaligned access and require fixing it up in the exception
163 handler.) 143 handler.)
164 144
165 This symbol should be selected by an 145 This symbol should be selected by an architecture if it can
166 perform unaligned accesses efficient 146 perform unaligned accesses efficiently to allow different
167 code paths to be selected for these 147 code paths to be selected for these cases. Some network
168 drivers, for example, could opt to n 148 drivers, for example, could opt to not fix up alignment
169 problems with received packets if do 149 problems with received packets if doing so would not help
170 much. 150 much.
171 151
172 See Documentation/core-api/unaligned 152 See Documentation/core-api/unaligned-memory-access.rst for more
173 information on the topic of unaligne 153 information on the topic of unaligned memory accesses.
174 154
175 config ARCH_USE_BUILTIN_BSWAP 155 config ARCH_USE_BUILTIN_BSWAP
176 bool 156 bool
177 help 157 help
178 Modern versions of GCC (since 4.4) h !! 158 Modern versions of GCC (since 4.4) have builtin functions
179 for handling byte-swapping. Using th !! 159 for handling byte-swapping. Using these, instead of the old
180 inline assembler that the architectu !! 160 inline assembler that the architecture code provides in the
181 __arch_bswapXX() macros, allows the !! 161 __arch_bswapXX() macros, allows the compiler to see what's
182 happening and offers more opportunit !! 162 happening and offers more opportunity for optimisation. In
183 particular, the compiler will be abl !! 163 particular, the compiler will be able to combine the byteswap
184 with a nearby load or store and use !! 164 with a nearby load or store and use load-and-swap or
185 store-and-swap instructions if the a !! 165 store-and-swap instructions if the architecture has them. It
186 should almost *never* result in code !! 166 should almost *never* result in code which is worse than the
187 hand-coded assembler in <asm/swab.h> !! 167 hand-coded assembler in <asm/swab.h>. But just in case it
188 does, the use of the builtins is opt !! 168 does, the use of the builtins is optional.
189 !! 169
190 Any architecture with load-and-swap !! 170 Any architecture with load-and-swap or store-and-swap
191 instructions should set this. And it !! 171 instructions should set this. And it shouldn't hurt to set it
192 on architectures that don't have suc !! 172 on architectures that don't have such instructions.
193 173
194 config KRETPROBES 174 config KRETPROBES
195 def_bool y 175 def_bool y
196 depends on KPROBES && (HAVE_KRETPROBES 176 depends on KPROBES && (HAVE_KRETPROBES || HAVE_RETHOOK)
197 177
198 config KRETPROBE_ON_RETHOOK 178 config KRETPROBE_ON_RETHOOK
199 def_bool y 179 def_bool y
200 depends on HAVE_RETHOOK 180 depends on HAVE_RETHOOK
201 depends on KRETPROBES 181 depends on KRETPROBES
202 select RETHOOK 182 select RETHOOK
203 183
204 config USER_RETURN_NOTIFIER 184 config USER_RETURN_NOTIFIER
205 bool 185 bool
206 depends on HAVE_USER_RETURN_NOTIFIER 186 depends on HAVE_USER_RETURN_NOTIFIER
207 help 187 help
208 Provide a kernel-internal notificati 188 Provide a kernel-internal notification when a cpu is about to
209 switch to user mode. 189 switch to user mode.
210 190
211 config HAVE_IOREMAP_PROT 191 config HAVE_IOREMAP_PROT
212 bool 192 bool
213 193
214 config HAVE_KPROBES 194 config HAVE_KPROBES
215 bool 195 bool
216 196
217 config HAVE_KRETPROBES 197 config HAVE_KRETPROBES
218 bool 198 bool
219 199
220 config HAVE_OPTPROBES 200 config HAVE_OPTPROBES
221 bool 201 bool
222 202
223 config HAVE_KPROBES_ON_FTRACE 203 config HAVE_KPROBES_ON_FTRACE
224 bool 204 bool
225 205
226 config ARCH_CORRECT_STACKTRACE_ON_KRETPROBE 206 config ARCH_CORRECT_STACKTRACE_ON_KRETPROBE
227 bool 207 bool
228 help 208 help
229 Since kretprobes modifies return add 209 Since kretprobes modifies return address on the stack, the
230 stacktrace may see the kretprobe tra 210 stacktrace may see the kretprobe trampoline address instead
231 of correct one. If the architecture 211 of correct one. If the architecture stacktrace code and
232 unwinder can adjust such entries, se 212 unwinder can adjust such entries, select this configuration.
233 213
234 config HAVE_FUNCTION_ERROR_INJECTION 214 config HAVE_FUNCTION_ERROR_INJECTION
235 bool 215 bool
236 216
237 config HAVE_NMI 217 config HAVE_NMI
238 bool 218 bool
239 219
240 config HAVE_FUNCTION_DESCRIPTORS 220 config HAVE_FUNCTION_DESCRIPTORS
241 bool 221 bool
242 222
243 config TRACE_IRQFLAGS_SUPPORT 223 config TRACE_IRQFLAGS_SUPPORT
244 bool 224 bool
245 225
246 config TRACE_IRQFLAGS_NMI_SUPPORT 226 config TRACE_IRQFLAGS_NMI_SUPPORT
247 bool 227 bool
248 228
249 # 229 #
250 # An arch should select this if it provides al 230 # An arch should select this if it provides all these things:
251 # 231 #
252 # task_pt_regs() in asm/process 232 # task_pt_regs() in asm/processor.h or asm/ptrace.h
253 # arch_has_single_step() if there is ha 233 # arch_has_single_step() if there is hardware single-step support
254 # arch_has_block_step() if there is ha 234 # arch_has_block_step() if there is hardware block-step support
255 # asm/syscall.h supplying asm- 235 # asm/syscall.h supplying asm-generic/syscall.h interface
256 # linux/regset.h user_regset in 236 # linux/regset.h user_regset interfaces
257 # CORE_DUMP_USE_REGSET #define'd in l 237 # CORE_DUMP_USE_REGSET #define'd in linux/elf.h
258 # TIF_SYSCALL_TRACE calls ptrace_r 238 # TIF_SYSCALL_TRACE calls ptrace_report_syscall_{entry,exit}
259 # TIF_NOTIFY_RESUME calls resume_u 239 # TIF_NOTIFY_RESUME calls resume_user_mode_work()
260 # 240 #
261 config HAVE_ARCH_TRACEHOOK 241 config HAVE_ARCH_TRACEHOOK
262 bool 242 bool
263 243
264 config HAVE_DMA_CONTIGUOUS 244 config HAVE_DMA_CONTIGUOUS
265 bool 245 bool
266 246
267 config GENERIC_SMP_IDLE_THREAD 247 config GENERIC_SMP_IDLE_THREAD
268 bool 248 bool
269 249
270 config GENERIC_IDLE_POLL_SETUP 250 config GENERIC_IDLE_POLL_SETUP
271 bool 251 bool
272 252
273 config ARCH_HAS_FORTIFY_SOURCE 253 config ARCH_HAS_FORTIFY_SOURCE
274 bool 254 bool
275 help 255 help
276 An architecture should select this w 256 An architecture should select this when it can successfully
277 build and run with CONFIG_FORTIFY_SO 257 build and run with CONFIG_FORTIFY_SOURCE.
278 258
279 # 259 #
280 # Select if the arch provides a historic keepi 260 # Select if the arch provides a historic keepinit alias for the retain_initrd
281 # command line option 261 # command line option
282 # 262 #
283 config ARCH_HAS_KEEPINITRD 263 config ARCH_HAS_KEEPINITRD
284 bool 264 bool
285 265
286 # 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
287 config ARCH_HAS_SET_MEMORY 267 config ARCH_HAS_SET_MEMORY
288 bool 268 bool
289 269
290 # Select if arch has all set_direct_map_invali 270 # Select if arch has all set_direct_map_invalid/default() functions
291 config ARCH_HAS_SET_DIRECT_MAP 271 config ARCH_HAS_SET_DIRECT_MAP
292 bool 272 bool
293 273
294 # 274 #
295 # Select if the architecture provides the arch 275 # Select if the architecture provides the arch_dma_set_uncached symbol to
296 # either provide an uncached segment alias for 276 # either provide an uncached segment alias for a DMA allocation, or
297 # to remap the page tables in place. 277 # to remap the page tables in place.
298 # 278 #
299 config ARCH_HAS_DMA_SET_UNCACHED 279 config ARCH_HAS_DMA_SET_UNCACHED
300 bool 280 bool
301 281
302 # 282 #
303 # Select if the architectures provides the arc 283 # Select if the architectures provides the arch_dma_clear_uncached symbol
304 # to undo an in-place page table remap for unc 284 # to undo an in-place page table remap for uncached access.
305 # 285 #
306 config ARCH_HAS_DMA_CLEAR_UNCACHED 286 config ARCH_HAS_DMA_CLEAR_UNCACHED
307 bool 287 bool
308 288
309 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
310 bool 291 bool
311 292
312 # The architecture has a per-task state that i !! 293 # Select if arch has its private alloc_task_struct() function
313 config ARCH_HAS_CPU_PASID !! 294 config ARCH_TASK_STRUCT_ALLOCATOR
314 bool 295 bool
315 select IOMMU_MM_DATA <<
316 296
317 config HAVE_ARCH_THREAD_STRUCT_WHITELIST 297 config HAVE_ARCH_THREAD_STRUCT_WHITELIST
318 bool 298 bool
>> 299 depends on !ARCH_TASK_STRUCT_ALLOCATOR
319 help 300 help
320 An architecture should select this t 301 An architecture should select this to provide hardened usercopy
321 knowledge about what region of the t 302 knowledge about what region of the thread_struct should be
322 whitelisted for copying to userspace 303 whitelisted for copying to userspace. Normally this is only the
323 FPU registers. Specifically, arch_th 304 FPU registers. Specifically, arch_thread_struct_whitelist()
324 should be implemented. Without this, 305 should be implemented. Without this, the entire thread_struct
325 field in task_struct will be left wh 306 field in task_struct will be left whitelisted.
326 307
>> 308 # Select if arch has its private alloc_thread_stack() function
>> 309 config ARCH_THREAD_STACK_ALLOCATOR
>> 310 bool
>> 311
327 # Select if arch wants to size task_struct dyn 312 # Select if arch wants to size task_struct dynamically via arch_task_struct_size:
328 config ARCH_WANTS_DYNAMIC_TASK_STRUCT 313 config ARCH_WANTS_DYNAMIC_TASK_STRUCT
329 bool 314 bool
330 315
331 config ARCH_WANTS_NO_INSTR 316 config ARCH_WANTS_NO_INSTR
332 bool 317 bool
333 help 318 help
334 An architecture should select this i 319 An architecture should select this if the noinstr macro is being used on
335 functions to denote that the toolcha 320 functions to denote that the toolchain should avoid instrumenting such
336 functions and is required for correc 321 functions and is required for correctness.
337 322
338 config ARCH_32BIT_OFF_T 323 config ARCH_32BIT_OFF_T
339 bool 324 bool
340 depends on !64BIT 325 depends on !64BIT
341 help 326 help
342 All new 32-bit architectures should 327 All new 32-bit architectures should have 64-bit off_t type on
343 userspace side which corresponds to 328 userspace side which corresponds to the loff_t kernel type. This
344 is the requirement for modern ABIs. 329 is the requirement for modern ABIs. Some existing architectures
345 still support 32-bit off_t. This opt 330 still support 32-bit off_t. This option is enabled for all such
346 architectures explicitly. 331 architectures explicitly.
347 332
348 # Selected by 64 bit architectures which have 333 # Selected by 64 bit architectures which have a 32 bit f_tinode in struct ustat
349 config ARCH_32BIT_USTAT_F_TINODE 334 config ARCH_32BIT_USTAT_F_TINODE
350 bool 335 bool
351 336
352 config HAVE_ASM_MODVERSIONS 337 config HAVE_ASM_MODVERSIONS
353 bool 338 bool
354 help 339 help
355 This symbol should be selected by an 340 This symbol should be selected by an architecture if it provides
356 <asm/asm-prototypes.h> to support th 341 <asm/asm-prototypes.h> to support the module versioning for symbols
357 exported from assembly code. 342 exported from assembly code.
358 343
359 config HAVE_REGS_AND_STACK_ACCESS_API 344 config HAVE_REGS_AND_STACK_ACCESS_API
360 bool 345 bool
361 help 346 help
362 This symbol should be selected by an 347 This symbol should be selected by an architecture if it supports
363 the API needed to access registers a 348 the API needed to access registers and stack entries from pt_regs,
364 declared in asm/ptrace.h 349 declared in asm/ptrace.h
365 For example the kprobes-based event 350 For example the kprobes-based event tracer needs this API.
366 351
367 config HAVE_RSEQ 352 config HAVE_RSEQ
368 bool 353 bool
369 depends on HAVE_REGS_AND_STACK_ACCESS_ 354 depends on HAVE_REGS_AND_STACK_ACCESS_API
370 help 355 help
371 This symbol should be selected by an 356 This symbol should be selected by an architecture if it
372 supports an implementation of restar 357 supports an implementation of restartable sequences.
373 358
374 config HAVE_RUST <<
375 bool <<
376 help <<
377 This symbol should be selected by an <<
378 supports Rust. <<
379 <<
380 config HAVE_FUNCTION_ARG_ACCESS_API 359 config HAVE_FUNCTION_ARG_ACCESS_API
381 bool 360 bool
382 help 361 help
383 This symbol should be selected by an 362 This symbol should be selected by an architecture if it supports
384 the API needed to access function ar 363 the API needed to access function arguments from pt_regs,
385 declared in asm/ptrace.h 364 declared in asm/ptrace.h
386 365
387 config HAVE_HW_BREAKPOINT 366 config HAVE_HW_BREAKPOINT
388 bool 367 bool
389 depends on PERF_EVENTS 368 depends on PERF_EVENTS
390 369
391 config HAVE_MIXED_BREAKPOINTS_REGS 370 config HAVE_MIXED_BREAKPOINTS_REGS
392 bool 371 bool
393 depends on HAVE_HW_BREAKPOINT 372 depends on HAVE_HW_BREAKPOINT
394 help 373 help
395 Depending on the arch implementation 374 Depending on the arch implementation of hardware breakpoints,
396 some of them have separate registers 375 some of them have separate registers for data and instruction
397 breakpoints addresses, others have m 376 breakpoints addresses, others have mixed registers to store
398 them but define the access type in a 377 them but define the access type in a control register.
399 Select this option if your arch impl 378 Select this option if your arch implements breakpoints under the
400 latter fashion. 379 latter fashion.
401 380
402 config HAVE_USER_RETURN_NOTIFIER 381 config HAVE_USER_RETURN_NOTIFIER
403 bool 382 bool
404 383
405 config HAVE_PERF_EVENTS_NMI 384 config HAVE_PERF_EVENTS_NMI
406 bool 385 bool
407 help 386 help
408 System hardware can generate an NMI 387 System hardware can generate an NMI using the perf event
409 subsystem. Also has support for cal 388 subsystem. Also has support for calculating CPU cycle events
410 to determine how many clock cycles i 389 to determine how many clock cycles in a given period.
411 390
412 config HAVE_HARDLOCKUP_DETECTOR_PERF 391 config HAVE_HARDLOCKUP_DETECTOR_PERF
413 bool 392 bool
414 depends on HAVE_PERF_EVENTS_NMI 393 depends on HAVE_PERF_EVENTS_NMI
415 help 394 help
416 The arch chooses to use the generic 395 The arch chooses to use the generic perf-NMI-based hardlockup
417 detector. Must define HAVE_PERF_EVEN 396 detector. Must define HAVE_PERF_EVENTS_NMI.
418 397
419 config HAVE_HARDLOCKUP_DETECTOR_ARCH !! 398 config HAVE_NMI_WATCHDOG
>> 399 depends on HAVE_NMI
420 bool 400 bool
421 help 401 help
422 The arch provides its own hardlockup !! 402 The arch provides a low level NMI watchdog. It provides
423 of the generic ones. !! 403 asm/nmi.h, and defines its own arch_touch_nmi_watchdog().
424 404
425 It uses the same command line parame !! 405 config HAVE_HARDLOCKUP_DETECTOR_ARCH
426 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.
427 412
428 config HAVE_PERF_REGS 413 config HAVE_PERF_REGS
429 bool 414 bool
430 help 415 help
431 Support selective register dumps for 416 Support selective register dumps for perf events. This includes
432 bit-mapping of each registers and a 417 bit-mapping of each registers and a unique architecture id.
433 418
434 config HAVE_PERF_USER_STACK_DUMP 419 config HAVE_PERF_USER_STACK_DUMP
435 bool 420 bool
436 help 421 help
437 Support user stack dumps for perf ev 422 Support user stack dumps for perf event samples. This needs
438 access to the user stack pointer whi 423 access to the user stack pointer which is not unified across
439 architectures. 424 architectures.
440 425
441 config HAVE_ARCH_JUMP_LABEL 426 config HAVE_ARCH_JUMP_LABEL
442 bool 427 bool
443 428
444 config HAVE_ARCH_JUMP_LABEL_RELATIVE 429 config HAVE_ARCH_JUMP_LABEL_RELATIVE
445 bool 430 bool
446 431
447 config MMU_GATHER_TABLE_FREE 432 config MMU_GATHER_TABLE_FREE
448 bool 433 bool
449 434
450 config MMU_GATHER_RCU_TABLE_FREE 435 config MMU_GATHER_RCU_TABLE_FREE
451 bool 436 bool
452 select MMU_GATHER_TABLE_FREE 437 select MMU_GATHER_TABLE_FREE
453 438
454 config MMU_GATHER_PAGE_SIZE 439 config MMU_GATHER_PAGE_SIZE
455 bool 440 bool
456 441
457 config MMU_GATHER_NO_RANGE 442 config MMU_GATHER_NO_RANGE
458 bool 443 bool
459 select MMU_GATHER_MERGE_VMAS 444 select MMU_GATHER_MERGE_VMAS
460 445
461 config MMU_GATHER_NO_FLUSH_CACHE 446 config MMU_GATHER_NO_FLUSH_CACHE
462 bool 447 bool
463 448
464 config MMU_GATHER_MERGE_VMAS 449 config MMU_GATHER_MERGE_VMAS
465 bool 450 bool
466 451
467 config MMU_GATHER_NO_GATHER 452 config MMU_GATHER_NO_GATHER
468 bool 453 bool
469 depends on MMU_GATHER_TABLE_FREE 454 depends on MMU_GATHER_TABLE_FREE
470 455
471 config ARCH_WANT_IRQS_OFF_ACTIVATE_MM 456 config ARCH_WANT_IRQS_OFF_ACTIVATE_MM
472 bool 457 bool
473 help 458 help
474 Temporary select until all architect 459 Temporary select until all architectures can be converted to have
475 irqs disabled over activate_mm. Arch 460 irqs disabled over activate_mm. Architectures that do IPI based TLB
476 shootdowns should enable this. 461 shootdowns should enable this.
477 462
478 # Use normal mm refcounting for MMU_LAZY_TLB k <<
479 # MMU_LAZY_TLB_REFCOUNT=n can improve the scal <<
480 # to/from kernel threads when the same mm is r <<
481 # multi-threaded application), by reducing con <<
482 # <<
483 # This can be disabled if the architecture ens <<
484 # "lazy tlb" beyond its final refcount (i.e., <<
485 # or its kernel page tables). This could be ar <<
486 # final exit(2) TLB flush, for example. <<
487 # <<
488 # To implement this, an arch *must*: <<
489 # Ensure the _lazy_tlb variants of mmgrab/mmdr <<
490 # the lazy tlb reference of a kthread's ->acti <<
491 # converted already). <<
492 config MMU_LAZY_TLB_REFCOUNT <<
493 def_bool y <<
494 depends on !MMU_LAZY_TLB_SHOOTDOWN <<
495 <<
496 # This option allows MMU_LAZY_TLB_REFCOUNT=n. <<
497 # mm as a lazy tlb beyond its last reference c <<
498 # users before the mm is deallocated. __mmdrop <<
499 # be using the mm as a lazy tlb, so that they <<
500 # init_mm for their active mm. mm_cpumask(mm) <<
501 # may be using mm as a lazy tlb mm. <<
502 # <<
503 # To implement this, an arch *must*: <<
504 # - At the time of the final mmdrop of the mm, <<
505 # at least all possible CPUs in which the mm <<
506 # - It must meet the requirements for MMU_LAZY <<
507 config MMU_LAZY_TLB_SHOOTDOWN <<
508 bool <<
509 <<
510 config ARCH_HAVE_NMI_SAFE_CMPXCHG 463 config ARCH_HAVE_NMI_SAFE_CMPXCHG
511 bool 464 bool
512 465
513 config ARCH_HAVE_EXTRA_ELF_NOTES <<
514 bool <<
515 help <<
516 An architecture should select this i <<
517 arch-specific ELF note section to co <<
518 functions: elf_coredump_extra_notes_ <<
519 elf_coredump_extra_notes_write() whi <<
520 dumper. <<
521 <<
522 config ARCH_HAS_NMI_SAFE_THIS_CPU_OPS <<
523 bool <<
524 <<
525 config HAVE_ALIGNED_STRUCT_PAGE 466 config HAVE_ALIGNED_STRUCT_PAGE
526 bool 467 bool
527 help 468 help
528 This makes sure that struct pages ar 469 This makes sure that struct pages are double word aligned and that
529 e.g. the SLUB allocator can perform 470 e.g. the SLUB allocator can perform double word atomic operations
530 on a struct page for better performa 471 on a struct page for better performance. However selecting this
531 might increase the size of a struct 472 might increase the size of a struct page by a word.
532 473
533 config HAVE_CMPXCHG_LOCAL 474 config HAVE_CMPXCHG_LOCAL
534 bool 475 bool
535 476
536 config HAVE_CMPXCHG_DOUBLE 477 config HAVE_CMPXCHG_DOUBLE
537 bool 478 bool
538 479
539 config ARCH_WEAK_RELEASE_ACQUIRE 480 config ARCH_WEAK_RELEASE_ACQUIRE
540 bool 481 bool
541 482
542 config ARCH_WANT_IPC_PARSE_VERSION 483 config ARCH_WANT_IPC_PARSE_VERSION
543 bool 484 bool
544 485
545 config ARCH_WANT_COMPAT_IPC_PARSE_VERSION 486 config ARCH_WANT_COMPAT_IPC_PARSE_VERSION
546 bool 487 bool
547 488
548 config ARCH_WANT_OLD_COMPAT_IPC 489 config ARCH_WANT_OLD_COMPAT_IPC
549 select ARCH_WANT_COMPAT_IPC_PARSE_VERS 490 select ARCH_WANT_COMPAT_IPC_PARSE_VERSION
550 bool 491 bool
551 492
552 config HAVE_ARCH_SECCOMP 493 config HAVE_ARCH_SECCOMP
553 bool 494 bool
554 help 495 help
555 An arch should select this symbol to 496 An arch should select this symbol to support seccomp mode 1 (the fixed
556 syscall policy), and must provide an 497 syscall policy), and must provide an overrides for __NR_seccomp_sigreturn,
557 and compat syscalls if the asm-gener 498 and compat syscalls if the asm-generic/seccomp.h defaults need adjustment:
558 - __NR_seccomp_read_32 499 - __NR_seccomp_read_32
559 - __NR_seccomp_write_32 500 - __NR_seccomp_write_32
560 - __NR_seccomp_exit_32 501 - __NR_seccomp_exit_32
561 - __NR_seccomp_sigreturn_32 502 - __NR_seccomp_sigreturn_32
562 503
563 config HAVE_ARCH_SECCOMP_FILTER 504 config HAVE_ARCH_SECCOMP_FILTER
564 bool 505 bool
565 select HAVE_ARCH_SECCOMP 506 select HAVE_ARCH_SECCOMP
566 help 507 help
567 An arch should select this symbol if 508 An arch should select this symbol if it provides all of these things:
568 - all the requirements for HAVE_ARCH 509 - all the requirements for HAVE_ARCH_SECCOMP
569 - syscall_get_arch() 510 - syscall_get_arch()
570 - syscall_get_arguments() 511 - syscall_get_arguments()
571 - syscall_rollback() 512 - syscall_rollback()
572 - syscall_set_return_value() 513 - syscall_set_return_value()
573 - SIGSYS siginfo_t support 514 - SIGSYS siginfo_t support
574 - secure_computing is called from a 515 - secure_computing is called from a ptrace_event()-safe context
575 - secure_computing return value is c 516 - secure_computing return value is checked and a return value of -1
576 results in the system call being s 517 results in the system call being skipped immediately.
577 - seccomp syscall wired up 518 - seccomp syscall wired up
578 - if !HAVE_SPARSE_SYSCALL_NR, have S 519 - if !HAVE_SPARSE_SYSCALL_NR, have SECCOMP_ARCH_NATIVE,
579 SECCOMP_ARCH_NATIVE_NR, SECCOMP_AR 520 SECCOMP_ARCH_NATIVE_NR, SECCOMP_ARCH_NATIVE_NAME defined. If
580 COMPAT is supported, have the SECC 521 COMPAT is supported, have the SECCOMP_ARCH_COMPAT* defines too.
581 522
582 config SECCOMP 523 config SECCOMP
583 prompt "Enable seccomp to safely execu 524 prompt "Enable seccomp to safely execute untrusted bytecode"
584 def_bool y 525 def_bool y
585 depends on HAVE_ARCH_SECCOMP 526 depends on HAVE_ARCH_SECCOMP
586 help 527 help
587 This kernel feature is useful for nu 528 This kernel feature is useful for number crunching applications
588 that may need to handle untrusted by 529 that may need to handle untrusted bytecode during their
589 execution. By using pipes or other t 530 execution. By using pipes or other transports made available
590 to the process as file descriptors s 531 to the process as file descriptors supporting the read/write
591 syscalls, it's possible to isolate t 532 syscalls, it's possible to isolate those applications in their
592 own address space using seccomp. Onc 533 own address space using seccomp. Once seccomp is enabled via
593 prctl(PR_SET_SECCOMP) or the seccomp 534 prctl(PR_SET_SECCOMP) or the seccomp() syscall, it cannot be
594 disabled and the task is only allowe 535 disabled and the task is only allowed to execute a few safe
595 syscalls defined by each seccomp mod 536 syscalls defined by each seccomp mode.
596 537
597 If unsure, say Y. 538 If unsure, say Y.
598 539
599 config SECCOMP_FILTER 540 config SECCOMP_FILTER
600 def_bool y 541 def_bool y
601 depends on HAVE_ARCH_SECCOMP_FILTER && 542 depends on HAVE_ARCH_SECCOMP_FILTER && SECCOMP && NET
602 help 543 help
603 Enable tasks to build secure computi 544 Enable tasks to build secure computing environments defined
604 in terms of Berkeley Packet Filter p 545 in terms of Berkeley Packet Filter programs which implement
605 task-defined system call filtering p 546 task-defined system call filtering polices.
606 547
607 See Documentation/userspace-api/secc 548 See Documentation/userspace-api/seccomp_filter.rst for details.
608 549
609 config SECCOMP_CACHE_DEBUG 550 config SECCOMP_CACHE_DEBUG
610 bool "Show seccomp filter cache status 551 bool "Show seccomp filter cache status in /proc/pid/seccomp_cache"
611 depends on SECCOMP_FILTER && !HAVE_SPA 552 depends on SECCOMP_FILTER && !HAVE_SPARSE_SYSCALL_NR
612 depends on PROC_FS 553 depends on PROC_FS
613 help 554 help
614 This enables the /proc/pid/seccomp_c 555 This enables the /proc/pid/seccomp_cache interface to monitor
615 seccomp cache data. The file format 556 seccomp cache data. The file format is subject to change. Reading
616 the file requires CAP_SYS_ADMIN. 557 the file requires CAP_SYS_ADMIN.
617 558
618 This option is for debugging only. E 559 This option is for debugging only. Enabling presents the risk that
619 an adversary may be able to infer th 560 an adversary may be able to infer the seccomp filter logic.
620 561
621 If unsure, say N. 562 If unsure, say N.
622 563
623 config HAVE_ARCH_STACKLEAK 564 config HAVE_ARCH_STACKLEAK
624 bool 565 bool
625 help 566 help
626 An architecture should select this i 567 An architecture should select this if it has the code which
627 fills the used part of the kernel st 568 fills the used part of the kernel stack with the STACKLEAK_POISON
628 value before returning from system c 569 value before returning from system calls.
629 570
630 config HAVE_STACKPROTECTOR 571 config HAVE_STACKPROTECTOR
631 bool 572 bool
632 help 573 help
633 An arch should select this symbol if 574 An arch should select this symbol if:
634 - it has implemented a stack canary 575 - it has implemented a stack canary (e.g. __stack_chk_guard)
635 576
636 config STACKPROTECTOR 577 config STACKPROTECTOR
637 bool "Stack Protector buffer overflow 578 bool "Stack Protector buffer overflow detection"
638 depends on HAVE_STACKPROTECTOR 579 depends on HAVE_STACKPROTECTOR
639 depends on $(cc-option,-fstack-protect 580 depends on $(cc-option,-fstack-protector)
640 default y 581 default y
641 help 582 help
642 This option turns on the "stack-prot 583 This option turns on the "stack-protector" GCC feature. This
643 feature puts, at the beginning of fu 584 feature puts, at the beginning of functions, a canary value on
644 the stack just before the return add 585 the stack just before the return address, and validates
645 the value just before actually retur 586 the value just before actually returning. Stack based buffer
646 overflows (that need to overwrite th 587 overflows (that need to overwrite this return address) now also
647 overwrite the canary, which gets det 588 overwrite the canary, which gets detected and the attack is then
648 neutralized via a kernel panic. 589 neutralized via a kernel panic.
649 590
650 Functions will have the stack-protec 591 Functions will have the stack-protector canary logic added if they
651 have an 8-byte or larger character a 592 have an 8-byte or larger character array on the stack.
652 593
653 This feature requires gcc version 4. 594 This feature requires gcc version 4.2 or above, or a distribution
654 gcc with the feature backported ("-f 595 gcc with the feature backported ("-fstack-protector").
655 596
656 On an x86 "defconfig" build, this fe 597 On an x86 "defconfig" build, this feature adds canary checks to
657 about 3% of all kernel functions, wh 598 about 3% of all kernel functions, which increases kernel code size
658 by about 0.3%. 599 by about 0.3%.
659 600
660 config STACKPROTECTOR_STRONG 601 config STACKPROTECTOR_STRONG
661 bool "Strong Stack Protector" 602 bool "Strong Stack Protector"
662 depends on STACKPROTECTOR 603 depends on STACKPROTECTOR
663 depends on $(cc-option,-fstack-protect 604 depends on $(cc-option,-fstack-protector-strong)
664 default y 605 default y
665 help 606 help
666 Functions will have the stack-protec 607 Functions will have the stack-protector canary logic added in any
667 of the following conditions: 608 of the following conditions:
668 609
669 - local variable's address used as p 610 - local variable's address used as part of the right hand side of an
670 assignment or function argument 611 assignment or function argument
671 - local variable is an array (or uni 612 - local variable is an array (or union containing an array),
672 regardless of array type or length 613 regardless of array type or length
673 - uses register local variables 614 - uses register local variables
674 615
675 This feature requires gcc version 4. 616 This feature requires gcc version 4.9 or above, or a distribution
676 gcc with the feature backported ("-f 617 gcc with the feature backported ("-fstack-protector-strong").
677 618
678 On an x86 "defconfig" build, this fe 619 On an x86 "defconfig" build, this feature adds canary checks to
679 about 20% of all kernel functions, w 620 about 20% of all kernel functions, which increases the kernel code
680 size by about 2%. 621 size by about 2%.
681 622
682 config ARCH_SUPPORTS_SHADOW_CALL_STACK 623 config ARCH_SUPPORTS_SHADOW_CALL_STACK
683 bool 624 bool
684 help 625 help
685 An architecture should select this i 626 An architecture should select this if it supports the compiler's
686 Shadow Call Stack and implements run 627 Shadow Call Stack and implements runtime support for shadow stack
687 switching. 628 switching.
688 629
689 config SHADOW_CALL_STACK 630 config SHADOW_CALL_STACK
690 bool "Shadow Call Stack" 631 bool "Shadow Call Stack"
691 depends on ARCH_SUPPORTS_SHADOW_CALL_S 632 depends on ARCH_SUPPORTS_SHADOW_CALL_STACK
692 depends on DYNAMIC_FTRACE_WITH_ARGS || !! 633 depends on DYNAMIC_FTRACE_WITH_REGS || !FUNCTION_GRAPH_TRACER
693 depends on MMU <<
694 help 634 help
695 This option enables the compiler's S 635 This option enables the compiler's Shadow Call Stack, which
696 uses a shadow stack to protect funct 636 uses a shadow stack to protect function return addresses from
697 being overwritten by an attacker. Mo 637 being overwritten by an attacker. More information can be found
698 in the compiler's documentation: 638 in the compiler's documentation:
699 639
700 - Clang: https://clang.llvm.org/docs 640 - Clang: https://clang.llvm.org/docs/ShadowCallStack.html
701 - GCC: https://gcc.gnu.org/onlinedoc 641 - GCC: https://gcc.gnu.org/onlinedocs/gcc/Instrumentation-Options.html#Instrumentation-Options
702 642
703 Note that security guarantees in the 643 Note that security guarantees in the kernel differ from the
704 ones documented for user space. The 644 ones documented for user space. The kernel must store addresses
705 of shadow stacks in memory, which me 645 of shadow stacks in memory, which means an attacker capable of
706 reading and writing arbitrary memory 646 reading and writing arbitrary memory may be able to locate them
707 and hijack control flow by modifying 647 and hijack control flow by modifying the stacks.
708 648
709 config DYNAMIC_SCS <<
710 bool <<
711 help <<
712 Set by the arch code if it relies on <<
713 shadow call stack push and pop instr <<
714 compiler. <<
715 <<
716 config LTO 649 config LTO
717 bool 650 bool
718 help 651 help
719 Selected if the kernel will be built 652 Selected if the kernel will be built using the compiler's LTO feature.
720 653
721 config LTO_CLANG 654 config LTO_CLANG
722 bool 655 bool
723 select LTO 656 select LTO
724 help 657 help
725 Selected if the kernel will be built 658 Selected if the kernel will be built using Clang's LTO feature.
726 659
727 config ARCH_SUPPORTS_LTO_CLANG 660 config ARCH_SUPPORTS_LTO_CLANG
728 bool 661 bool
729 help 662 help
730 An architecture should select this o 663 An architecture should select this option if it supports:
731 - compiling with Clang, 664 - compiling with Clang,
732 - compiling inline assembly with Cla 665 - compiling inline assembly with Clang's integrated assembler,
733 - and linking with LLD. 666 - and linking with LLD.
734 667
735 config ARCH_SUPPORTS_LTO_CLANG_THIN 668 config ARCH_SUPPORTS_LTO_CLANG_THIN
736 bool 669 bool
737 help 670 help
738 An architecture should select this o 671 An architecture should select this option if it can support Clang's
739 ThinLTO mode. 672 ThinLTO mode.
740 673
741 config HAS_LTO_CLANG 674 config HAS_LTO_CLANG
742 def_bool y 675 def_bool y
743 depends on CC_IS_CLANG && LD_IS_LLD && 676 depends on CC_IS_CLANG && LD_IS_LLD && AS_IS_LLVM
744 depends on $(success,$(NM) --help | he 677 depends on $(success,$(NM) --help | head -n 1 | grep -qi llvm)
745 depends on $(success,$(AR) --help | he 678 depends on $(success,$(AR) --help | head -n 1 | grep -qi llvm)
746 depends on ARCH_SUPPORTS_LTO_CLANG 679 depends on ARCH_SUPPORTS_LTO_CLANG
747 depends on !FTRACE_MCOUNT_USE_RECORDMC 680 depends on !FTRACE_MCOUNT_USE_RECORDMCOUNT
748 # https://github.com/ClangBuiltLinux/l !! 681 depends on !KASAN || KASAN_HW_TAGS
749 depends on (!KASAN || KASAN_HW_TAGS || <<
750 depends on (!KCOV || CLANG_VERSION >= <<
751 depends on !GCOV_KERNEL 682 depends on !GCOV_KERNEL
752 help 683 help
753 The compiler and Kconfig options sup 684 The compiler and Kconfig options support building with Clang's
754 LTO. 685 LTO.
755 686
756 choice 687 choice
757 prompt "Link Time Optimization (LTO)" 688 prompt "Link Time Optimization (LTO)"
758 default LTO_NONE 689 default LTO_NONE
759 help 690 help
760 This option enables Link Time Optimi 691 This option enables Link Time Optimization (LTO), which allows the
761 compiler to optimize binaries global 692 compiler to optimize binaries globally.
762 693
763 If unsure, select LTO_NONE. Note tha 694 If unsure, select LTO_NONE. Note that LTO is very resource-intensive
764 so it's disabled by default. 695 so it's disabled by default.
765 696
766 config LTO_NONE 697 config LTO_NONE
767 bool "None" 698 bool "None"
768 help 699 help
769 Build the kernel normally, without L 700 Build the kernel normally, without Link Time Optimization (LTO).
770 701
771 config LTO_CLANG_FULL 702 config LTO_CLANG_FULL
772 bool "Clang Full LTO (EXPERIMENTAL)" 703 bool "Clang Full LTO (EXPERIMENTAL)"
773 depends on HAS_LTO_CLANG 704 depends on HAS_LTO_CLANG
774 depends on !COMPILE_TEST 705 depends on !COMPILE_TEST
775 select LTO_CLANG 706 select LTO_CLANG
776 help 707 help
777 This option enables Clang's full Lin !! 708 This option enables Clang's full Link Time Optimization (LTO), which
778 allows the compiler to optimize the !! 709 allows the compiler to optimize the kernel globally. If you enable
779 this option, the compiler generates !! 710 this option, the compiler generates LLVM bitcode instead of ELF
780 object files, and the actual compila !! 711 object files, and the actual compilation from bitcode happens at
781 the LTO link step, which may take se !! 712 the LTO link step, which may take several minutes depending on the
782 kernel configuration. More informati !! 713 kernel configuration. More information can be found from LLVM's
783 documentation: !! 714 documentation:
784 715
785 https://llvm.org/docs/LinkTimeOpti 716 https://llvm.org/docs/LinkTimeOptimization.html
786 717
787 During link time, this option can us 718 During link time, this option can use a large amount of RAM, and
788 may take much longer than the ThinLT 719 may take much longer than the ThinLTO option.
789 720
790 config LTO_CLANG_THIN 721 config LTO_CLANG_THIN
791 bool "Clang ThinLTO (EXPERIMENTAL)" 722 bool "Clang ThinLTO (EXPERIMENTAL)"
792 depends on HAS_LTO_CLANG && ARCH_SUPPO 723 depends on HAS_LTO_CLANG && ARCH_SUPPORTS_LTO_CLANG_THIN
793 select LTO_CLANG 724 select LTO_CLANG
794 help 725 help
795 This option enables Clang's ThinLTO, 726 This option enables Clang's ThinLTO, which allows for parallel
796 optimization and faster incremental 727 optimization and faster incremental compiles compared to the
797 CONFIG_LTO_CLANG_FULL option. More i 728 CONFIG_LTO_CLANG_FULL option. More information can be found
798 from Clang's documentation: 729 from Clang's documentation:
799 730
800 https://clang.llvm.org/docs/ThinLT 731 https://clang.llvm.org/docs/ThinLTO.html
801 732
802 If unsure, say Y. 733 If unsure, say Y.
803 endchoice 734 endchoice
804 735
805 config ARCH_SUPPORTS_CFI_CLANG 736 config ARCH_SUPPORTS_CFI_CLANG
806 bool 737 bool
807 help 738 help
808 An architecture should select this o 739 An architecture should select this option if it can support Clang's
809 Control-Flow Integrity (CFI) checkin 740 Control-Flow Integrity (CFI) checking.
810 741
811 config ARCH_USES_CFI_TRAPS <<
812 bool <<
813 <<
814 config CFI_CLANG 742 config CFI_CLANG
815 bool "Use Clang's Control Flow Integri 743 bool "Use Clang's Control Flow Integrity (CFI)"
816 depends on ARCH_SUPPORTS_CFI_CLANG !! 744 depends on LTO_CLANG && ARCH_SUPPORTS_CFI_CLANG
817 depends on $(cc-option,-fsanitize=kcfi !! 745 depends on CLANG_VERSION >= 140000
>> 746 select KALLSYMS
818 help 747 help
819 This option enables Clang's forward- !! 748 This option enables Clang’s forward-edge Control Flow Integrity
820 (CFI) checking, where the compiler i 749 (CFI) checking, where the compiler injects a runtime check to each
821 indirect function call to ensure the 750 indirect function call to ensure the target is a valid function with
822 the correct static type. This restri 751 the correct static type. This restricts possible call targets and
823 makes it more difficult for an attac 752 makes it more difficult for an attacker to exploit bugs that allow
824 the modification of stored function 753 the modification of stored function pointers. More information can be
825 found from Clang's documentation: 754 found from Clang's documentation:
826 755
827 https://clang.llvm.org/docs/Contro 756 https://clang.llvm.org/docs/ControlFlowIntegrity.html
828 757
>> 758 config CFI_CLANG_SHADOW
>> 759 bool "Use CFI shadow to speed up cross-module checks"
>> 760 default y
>> 761 depends on CFI_CLANG && MODULES
>> 762 help
>> 763 If you select this option, the kernel builds a fast look-up table of
>> 764 CFI check functions in loaded modules to reduce performance overhead.
>> 765
>> 766 If unsure, say Y.
>> 767
829 config CFI_PERMISSIVE 768 config CFI_PERMISSIVE
830 bool "Use CFI in permissive mode" 769 bool "Use CFI in permissive mode"
831 depends on CFI_CLANG 770 depends on CFI_CLANG
832 help 771 help
833 When selected, Control Flow Integrit 772 When selected, Control Flow Integrity (CFI) violations result in a
834 warning instead of a kernel panic. T 773 warning instead of a kernel panic. This option should only be used
835 for finding indirect call type misma 774 for finding indirect call type mismatches during development.
836 775
837 If unsure, say N. 776 If unsure, say N.
838 777
839 config HAVE_ARCH_WITHIN_STACK_FRAMES 778 config HAVE_ARCH_WITHIN_STACK_FRAMES
840 bool 779 bool
841 help 780 help
842 An architecture should select this i 781 An architecture should select this if it can walk the kernel stack
843 frames to determine if an object is 782 frames to determine if an object is part of either the arguments
844 or local variables (i.e. that it exc 783 or local variables (i.e. that it excludes saved return addresses,
845 and similar) by implementing an inli 784 and similar) by implementing an inline arch_within_stack_frames(),
846 which is used by CONFIG_HARDENED_USE 785 which is used by CONFIG_HARDENED_USERCOPY.
847 786
848 config HAVE_CONTEXT_TRACKING_USER !! 787 config HAVE_CONTEXT_TRACKING
849 bool 788 bool
850 help 789 help
851 Provide kernel/user boundaries probe 790 Provide kernel/user boundaries probes necessary for subsystems
852 that need it, such as userspace RCU 791 that need it, such as userspace RCU extended quiescent state.
853 Syscalls need to be wrapped inside u 792 Syscalls need to be wrapped inside user_exit()-user_enter(), either
854 optimized behind static key or throu 793 optimized behind static key or through the slow path using TIF_NOHZ
855 flag. Exceptions handlers must be wr 794 flag. Exceptions handlers must be wrapped as well. Irqs are already
856 protected inside ct_irq_enter/ct_irq !! 795 protected inside rcu_irq_enter/rcu_irq_exit() but preemption or signal
857 handling on irq exit still need to b 796 handling on irq exit still need to be protected.
858 797
859 config HAVE_CONTEXT_TRACKING_USER_OFFSTACK !! 798 config HAVE_CONTEXT_TRACKING_OFFSTACK
860 bool 799 bool
861 help 800 help
862 Architecture neither relies on excep 801 Architecture neither relies on exception_enter()/exception_exit()
863 nor on schedule_user(). Also preempt 802 nor on schedule_user(). Also preempt_schedule_notrace() and
864 preempt_schedule_irq() can't be call 803 preempt_schedule_irq() can't be called in a preemptible section
865 while context tracking is CONTEXT_US 804 while context tracking is CONTEXT_USER. This feature reflects a sane
866 entry implementation where the follo 805 entry implementation where the following requirements are met on
867 critical entry code, ie: before user 806 critical entry code, ie: before user_exit() or after user_enter():
868 807
869 - Critical entry code isn't preempti 808 - Critical entry code isn't preemptible (or better yet:
870 not interruptible). 809 not interruptible).
871 - No use of RCU read side critical s !! 810 - No use of RCU read side critical sections, unless rcu_nmi_enter()
872 got called. 811 got called.
873 - No use of instrumentation, unless 812 - No use of instrumentation, unless instrumentation_begin() got
874 called. 813 called.
875 814
876 config HAVE_TIF_NOHZ 815 config HAVE_TIF_NOHZ
877 bool 816 bool
878 help 817 help
879 Arch relies on TIF_NOHZ and syscall 818 Arch relies on TIF_NOHZ and syscall slow path to implement context
880 tracking calls to user_enter()/user_ 819 tracking calls to user_enter()/user_exit().
881 820
882 config HAVE_VIRT_CPU_ACCOUNTING 821 config HAVE_VIRT_CPU_ACCOUNTING
883 bool 822 bool
884 823
885 config HAVE_VIRT_CPU_ACCOUNTING_IDLE 824 config HAVE_VIRT_CPU_ACCOUNTING_IDLE
886 bool 825 bool
887 help 826 help
888 Architecture has its own way to acco 827 Architecture has its own way to account idle CPU time and therefore
889 doesn't implement vtime_account_idle 828 doesn't implement vtime_account_idle().
890 829
891 config ARCH_HAS_SCALED_CPUTIME 830 config ARCH_HAS_SCALED_CPUTIME
892 bool 831 bool
893 832
894 config HAVE_VIRT_CPU_ACCOUNTING_GEN 833 config HAVE_VIRT_CPU_ACCOUNTING_GEN
895 bool 834 bool
896 default y if 64BIT 835 default y if 64BIT
897 help 836 help
898 With VIRT_CPU_ACCOUNTING_GEN, cputim 837 With VIRT_CPU_ACCOUNTING_GEN, cputime_t becomes 64-bit.
899 Before enabling this option, arch co 838 Before enabling this option, arch code must be audited
900 to ensure there are no races in conc 839 to ensure there are no races in concurrent read/write of
901 cputime_t. For example, reading/writ 840 cputime_t. For example, reading/writing 64-bit cputime_t on
902 some 32-bit arches may require multi 841 some 32-bit arches may require multiple accesses, so proper
903 locking is needed to protect against 842 locking is needed to protect against concurrent accesses.
904 843
905 config HAVE_IRQ_TIME_ACCOUNTING 844 config HAVE_IRQ_TIME_ACCOUNTING
906 bool 845 bool
907 help 846 help
908 Archs need to ensure they use a high 847 Archs need to ensure they use a high enough resolution clock to
909 support irq time accounting and then 848 support irq time accounting and then call enable_sched_clock_irqtime().
910 849
911 config HAVE_MOVE_PUD 850 config HAVE_MOVE_PUD
912 bool 851 bool
913 help 852 help
914 Architectures that select this are a 853 Architectures that select this are able to move page tables at the
915 PUD level. If there are only 3 page 854 PUD level. If there are only 3 page table levels, the move effectively
916 happens at the PGD level. 855 happens at the PGD level.
917 856
918 config HAVE_MOVE_PMD 857 config HAVE_MOVE_PMD
919 bool 858 bool
920 help 859 help
921 Archs that select this are able to m 860 Archs that select this are able to move page tables at the PMD level.
922 861
923 config HAVE_ARCH_TRANSPARENT_HUGEPAGE 862 config HAVE_ARCH_TRANSPARENT_HUGEPAGE
924 bool 863 bool
925 864
926 config HAVE_ARCH_TRANSPARENT_HUGEPAGE_PUD 865 config HAVE_ARCH_TRANSPARENT_HUGEPAGE_PUD
927 bool 866 bool
928 867
929 config HAVE_ARCH_HUGE_VMAP 868 config HAVE_ARCH_HUGE_VMAP
930 bool 869 bool
931 870
932 # 871 #
933 # Archs that select this would be capable of 872 # Archs that select this would be capable of PMD-sized vmaps (i.e.,
934 # arch_vmap_pmd_supported() returns true). Th 873 # arch_vmap_pmd_supported() returns true). The VM_ALLOW_HUGE_VMAP flag
935 # must be used to enable allocations to use h 874 # must be used to enable allocations to use hugepages.
936 # 875 #
937 config HAVE_ARCH_HUGE_VMALLOC 876 config HAVE_ARCH_HUGE_VMALLOC
938 depends on HAVE_ARCH_HUGE_VMAP 877 depends on HAVE_ARCH_HUGE_VMAP
939 bool 878 bool
940 879
941 config ARCH_WANT_HUGE_PMD_SHARE 880 config ARCH_WANT_HUGE_PMD_SHARE
942 bool 881 bool
943 882
944 # Archs that want to use pmd_mkwrite on kernel <<
945 # if there are no userspace memory management <<
946 config ARCH_WANT_KERNEL_PMD_MKWRITE <<
947 bool <<
948 <<
949 config ARCH_WANT_PMD_MKWRITE <<
950 def_bool TRANSPARENT_HUGEPAGE || ARCH_ <<
951 <<
952 config HAVE_ARCH_SOFT_DIRTY 883 config HAVE_ARCH_SOFT_DIRTY
953 bool 884 bool
954 885
955 config HAVE_MOD_ARCH_SPECIFIC 886 config HAVE_MOD_ARCH_SPECIFIC
956 bool 887 bool
957 help 888 help
958 The arch uses struct mod_arch_specif 889 The arch uses struct mod_arch_specific to store data. Many arches
959 just need a simple module loader wit 890 just need a simple module loader without arch specific data - those
960 should not enable this. 891 should not enable this.
961 892
962 config MODULES_USE_ELF_RELA 893 config MODULES_USE_ELF_RELA
963 bool 894 bool
964 help 895 help
965 Modules only use ELF RELA relocation 896 Modules only use ELF RELA relocations. Modules with ELF REL
966 relocations will give an error. 897 relocations will give an error.
967 898
968 config MODULES_USE_ELF_REL 899 config MODULES_USE_ELF_REL
969 bool 900 bool
970 help 901 help
971 Modules only use ELF REL relocations 902 Modules only use ELF REL relocations. Modules with ELF RELA
972 relocations will give an error. 903 relocations will give an error.
973 904
974 config ARCH_WANTS_MODULES_DATA_IN_VMALLOC 905 config ARCH_WANTS_MODULES_DATA_IN_VMALLOC
975 bool 906 bool
976 help 907 help
977 For architectures like powerpc/32 wh 908 For architectures like powerpc/32 which have constraints on module
978 allocation and need to allocate modu 909 allocation and need to allocate module data outside of module area.
979 910
980 config ARCH_WANTS_EXECMEM_LATE <<
981 bool <<
982 help <<
983 For architectures that do not alloca <<
984 boot, but rather require its initial <<
985 enough entropy for module space rand <<
986 arm64. <<
987 <<
988 config HAVE_IRQ_EXIT_ON_IRQ_STACK 911 config HAVE_IRQ_EXIT_ON_IRQ_STACK
989 bool 912 bool
990 help 913 help
991 Architecture doesn't only execute th 914 Architecture doesn't only execute the irq handler on the irq stack
992 but also irq_exit(). This way we can 915 but also irq_exit(). This way we can process softirqs on this irq
993 stack instead of switching to a new 916 stack instead of switching to a new one when we call __do_softirq()
994 in the end of an hardirq. 917 in the end of an hardirq.
995 This spares a stack switch and impro 918 This spares a stack switch and improves cache usage on softirq
996 processing. 919 processing.
997 920
998 config HAVE_SOFTIRQ_ON_OWN_STACK 921 config HAVE_SOFTIRQ_ON_OWN_STACK
999 bool 922 bool
1000 help 923 help
1001 Architecture provides a function to 924 Architecture provides a function to run __do_softirq() on a
1002 separate stack. 925 separate stack.
1003 926
1004 config SOFTIRQ_ON_OWN_STACK <<
1005 def_bool HAVE_SOFTIRQ_ON_OWN_STACK && <<
1006 <<
1007 config ALTERNATE_USER_ADDRESS_SPACE 927 config ALTERNATE_USER_ADDRESS_SPACE
1008 bool 928 bool
1009 help 929 help
1010 Architectures set this when the CPU 930 Architectures set this when the CPU uses separate address
1011 spaces for kernel and user space po 931 spaces for kernel and user space pointers. In this case, the
1012 access_ok() check on a __user point 932 access_ok() check on a __user pointer is skipped.
1013 933
1014 config PGTABLE_LEVELS 934 config PGTABLE_LEVELS
1015 int 935 int
1016 default 2 936 default 2
1017 937
1018 config ARCH_HAS_ELF_RANDOMIZE 938 config ARCH_HAS_ELF_RANDOMIZE
1019 bool 939 bool
1020 help 940 help
1021 An architecture supports choosing r 941 An architecture supports choosing randomized locations for
1022 stack, mmap, brk, and ET_DYN. Defin 942 stack, mmap, brk, and ET_DYN. Defined functions:
1023 - arch_mmap_rnd() 943 - arch_mmap_rnd()
1024 - arch_randomize_brk() 944 - arch_randomize_brk()
1025 945
1026 config HAVE_ARCH_MMAP_RND_BITS 946 config HAVE_ARCH_MMAP_RND_BITS
1027 bool 947 bool
1028 help 948 help
1029 An arch should select this symbol i 949 An arch should select this symbol if it supports setting a variable
1030 number of bits for use in establish 950 number of bits for use in establishing the base address for mmap
1031 allocations, has MMU enabled and pr 951 allocations, has MMU enabled and provides values for both:
1032 - ARCH_MMAP_RND_BITS_MIN 952 - ARCH_MMAP_RND_BITS_MIN
1033 - ARCH_MMAP_RND_BITS_MAX 953 - ARCH_MMAP_RND_BITS_MAX
1034 954
1035 config HAVE_EXIT_THREAD 955 config HAVE_EXIT_THREAD
1036 bool 956 bool
1037 help 957 help
1038 An architecture implements exit_thr 958 An architecture implements exit_thread.
1039 959
1040 config ARCH_MMAP_RND_BITS_MIN 960 config ARCH_MMAP_RND_BITS_MIN
1041 int 961 int
1042 962
1043 config ARCH_MMAP_RND_BITS_MAX 963 config ARCH_MMAP_RND_BITS_MAX
1044 int 964 int
1045 965
1046 config ARCH_MMAP_RND_BITS_DEFAULT 966 config ARCH_MMAP_RND_BITS_DEFAULT
1047 int 967 int
1048 968
1049 config ARCH_MMAP_RND_BITS 969 config ARCH_MMAP_RND_BITS
1050 int "Number of bits to use for ASLR o 970 int "Number of bits to use for ASLR of mmap base address" if EXPERT
1051 range ARCH_MMAP_RND_BITS_MIN ARCH_MMA 971 range ARCH_MMAP_RND_BITS_MIN ARCH_MMAP_RND_BITS_MAX
1052 default ARCH_MMAP_RND_BITS_DEFAULT if 972 default ARCH_MMAP_RND_BITS_DEFAULT if ARCH_MMAP_RND_BITS_DEFAULT
1053 default ARCH_MMAP_RND_BITS_MIN 973 default ARCH_MMAP_RND_BITS_MIN
1054 depends on HAVE_ARCH_MMAP_RND_BITS 974 depends on HAVE_ARCH_MMAP_RND_BITS
1055 help 975 help
1056 This value can be used to select th 976 This value can be used to select the number of bits to use to
1057 determine the random offset to the 977 determine the random offset to the base address of vma regions
1058 resulting from mmap allocations. Th 978 resulting from mmap allocations. This value will be bounded
1059 by the architecture's minimum and m 979 by the architecture's minimum and maximum supported values.
1060 980
1061 This value can be changed after boo 981 This value can be changed after boot using the
1062 /proc/sys/vm/mmap_rnd_bits tunable 982 /proc/sys/vm/mmap_rnd_bits tunable
1063 983
1064 config HAVE_ARCH_MMAP_RND_COMPAT_BITS 984 config HAVE_ARCH_MMAP_RND_COMPAT_BITS
1065 bool 985 bool
1066 help 986 help
1067 An arch should select this symbol i 987 An arch should select this symbol if it supports running applications
1068 in compatibility mode, supports set 988 in compatibility mode, supports setting a variable number of bits for
1069 use in establishing the base addres 989 use in establishing the base address for mmap allocations, has MMU
1070 enabled and provides values for bot 990 enabled and provides values for both:
1071 - ARCH_MMAP_RND_COMPAT_BITS_MIN 991 - ARCH_MMAP_RND_COMPAT_BITS_MIN
1072 - ARCH_MMAP_RND_COMPAT_BITS_MAX 992 - ARCH_MMAP_RND_COMPAT_BITS_MAX
1073 993
1074 config ARCH_MMAP_RND_COMPAT_BITS_MIN 994 config ARCH_MMAP_RND_COMPAT_BITS_MIN
1075 int 995 int
1076 996
1077 config ARCH_MMAP_RND_COMPAT_BITS_MAX 997 config ARCH_MMAP_RND_COMPAT_BITS_MAX
1078 int 998 int
1079 999
1080 config ARCH_MMAP_RND_COMPAT_BITS_DEFAULT 1000 config ARCH_MMAP_RND_COMPAT_BITS_DEFAULT
1081 int 1001 int
1082 1002
1083 config ARCH_MMAP_RND_COMPAT_BITS 1003 config ARCH_MMAP_RND_COMPAT_BITS
1084 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
1085 range ARCH_MMAP_RND_COMPAT_BITS_MIN A 1005 range ARCH_MMAP_RND_COMPAT_BITS_MIN ARCH_MMAP_RND_COMPAT_BITS_MAX
1086 default ARCH_MMAP_RND_COMPAT_BITS_DEF 1006 default ARCH_MMAP_RND_COMPAT_BITS_DEFAULT if ARCH_MMAP_RND_COMPAT_BITS_DEFAULT
1087 default ARCH_MMAP_RND_COMPAT_BITS_MIN 1007 default ARCH_MMAP_RND_COMPAT_BITS_MIN
1088 depends on HAVE_ARCH_MMAP_RND_COMPAT_ 1008 depends on HAVE_ARCH_MMAP_RND_COMPAT_BITS
1089 help 1009 help
1090 This value can be used to select th 1010 This value can be used to select the number of bits to use to
1091 determine the random offset to the 1011 determine the random offset to the base address of vma regions
1092 resulting from mmap allocations for 1012 resulting from mmap allocations for compatible applications This
1093 value will be bounded by the archit 1013 value will be bounded by the architecture's minimum and maximum
1094 supported values. 1014 supported values.
1095 1015
1096 This value can be changed after boo 1016 This value can be changed after boot using the
1097 /proc/sys/vm/mmap_rnd_compat_bits t 1017 /proc/sys/vm/mmap_rnd_compat_bits tunable
1098 1018
1099 config HAVE_ARCH_COMPAT_MMAP_BASES 1019 config HAVE_ARCH_COMPAT_MMAP_BASES
1100 bool 1020 bool
1101 help 1021 help
1102 This allows 64bit applications to i 1022 This allows 64bit applications to invoke 32-bit mmap() syscall
1103 and vice-versa 32-bit applications 1023 and vice-versa 32-bit applications to call 64-bit mmap().
1104 Required for applications doing dif 1024 Required for applications doing different bitness syscalls.
1105 1025
1106 config HAVE_PAGE_SIZE_4KB <<
1107 bool <<
1108 <<
1109 config HAVE_PAGE_SIZE_8KB <<
1110 bool <<
1111 <<
1112 config HAVE_PAGE_SIZE_16KB <<
1113 bool <<
1114 <<
1115 config HAVE_PAGE_SIZE_32KB <<
1116 bool <<
1117 <<
1118 config HAVE_PAGE_SIZE_64KB <<
1119 bool <<
1120 <<
1121 config HAVE_PAGE_SIZE_256KB <<
1122 bool <<
1123 <<
1124 choice <<
1125 prompt "MMU page size" <<
1126 <<
1127 config PAGE_SIZE_4KB <<
1128 bool "4KiB pages" <<
1129 depends on HAVE_PAGE_SIZE_4KB <<
1130 help <<
1131 This option select the standard 4Ki <<
1132 available option on many architectu <<
1133 minimize memory consumption and is <<
1134 memory systems. <<
1135 Some software that is written for x <<
1136 assumptions about the page size and <<
1137 <<
1138 config PAGE_SIZE_8KB <<
1139 bool "8KiB pages" <<
1140 depends on HAVE_PAGE_SIZE_8KB <<
1141 help <<
1142 This option is the only supported p <<
1143 processors, and can be slightly fas <<
1144 <<
1145 config PAGE_SIZE_16KB <<
1146 bool "16KiB pages" <<
1147 depends on HAVE_PAGE_SIZE_16KB <<
1148 help <<
1149 This option is usually a good compr <<
1150 consumption and performance for typ <<
1151 workloads, often saving a level of <<
1152 to 4KB pages as well as reducing TL <<
1153 per-page operations in the kernel a <<
1154 page cache. <<
1155 <<
1156 config PAGE_SIZE_32KB <<
1157 bool "32KiB pages" <<
1158 depends on HAVE_PAGE_SIZE_32KB <<
1159 help <<
1160 Using 32KiB page size will result i <<
1161 kernel at the price of higher memor <<
1162 16KiB pages. This option is availa <<
1163 Note that you will need a suitable <<
1164 support this. <<
1165 <<
1166 config PAGE_SIZE_64KB <<
1167 bool "64KiB pages" <<
1168 depends on HAVE_PAGE_SIZE_64KB <<
1169 help <<
1170 Using 64KiB page size will result i <<
1171 kernel at the price of much higher <<
1172 4KiB or 16KiB pages. <<
1173 This is not suitable for general-pu <<
1174 better performance may be worth the <<
1175 supercomputing or database applicat <<
1176 large in-memory data rather than sm <<
1177 <<
1178 config PAGE_SIZE_256KB <<
1179 bool "256KiB pages" <<
1180 depends on HAVE_PAGE_SIZE_256KB <<
1181 help <<
1182 256KiB pages have little practical <<
1183 memory usage. The kernel will only <<
1184 that have been compiled with '-zmax <<
1185 (the default is 64KiB or 4KiB on mo <<
1186 <<
1187 endchoice <<
1188 <<
1189 config PAGE_SIZE_LESS_THAN_64KB 1026 config PAGE_SIZE_LESS_THAN_64KB
1190 def_bool y 1027 def_bool y
>> 1028 depends on !ARM64_64K_PAGES
>> 1029 depends on !IA64_PAGE_SIZE_64KB
1191 depends on !PAGE_SIZE_64KB 1030 depends on !PAGE_SIZE_64KB
>> 1031 depends on !PARISC_PAGE_SIZE_64KB
1192 depends on PAGE_SIZE_LESS_THAN_256KB 1032 depends on PAGE_SIZE_LESS_THAN_256KB
1193 1033
1194 config PAGE_SIZE_LESS_THAN_256KB 1034 config PAGE_SIZE_LESS_THAN_256KB
1195 def_bool y 1035 def_bool y
1196 depends on !PAGE_SIZE_256KB 1036 depends on !PAGE_SIZE_256KB
1197 1037
1198 config PAGE_SHIFT <<
1199 int <<
1200 default 12 if PAGE_SIZE_4KB <<
1201 default 13 if PAGE_SIZE_8KB <<
1202 default 14 if PAGE_SIZE_16KB <<
1203 default 15 if PAGE_SIZE_32KB <<
1204 default 16 if PAGE_SIZE_64KB <<
1205 default 18 if PAGE_SIZE_256KB <<
1206 <<
1207 # This allows to use a set of generic functio 1038 # This allows to use a set of generic functions to determine mmap base
1208 # address by giving priority to top-down sche 1039 # address by giving priority to top-down scheme only if the process
1209 # is not in legacy mode (compat task, unlimit 1040 # is not in legacy mode (compat task, unlimited stack size or
1210 # sysctl_legacy_va_layout). 1041 # sysctl_legacy_va_layout).
1211 # Architecture that selects this option can p 1042 # Architecture that selects this option can provide its own version of:
1212 # - STACK_RND_MASK 1043 # - STACK_RND_MASK
1213 config ARCH_WANT_DEFAULT_TOPDOWN_MMAP_LAYOUT 1044 config ARCH_WANT_DEFAULT_TOPDOWN_MMAP_LAYOUT
1214 bool 1045 bool
1215 depends on MMU 1046 depends on MMU
1216 select ARCH_HAS_ELF_RANDOMIZE 1047 select ARCH_HAS_ELF_RANDOMIZE
1217 1048
1218 config HAVE_OBJTOOL 1049 config HAVE_OBJTOOL
1219 bool 1050 bool
1220 1051
1221 config HAVE_JUMP_LABEL_HACK 1052 config HAVE_JUMP_LABEL_HACK
1222 bool 1053 bool
1223 1054
1224 config HAVE_NOINSTR_HACK 1055 config HAVE_NOINSTR_HACK
1225 bool 1056 bool
1226 1057
1227 config HAVE_NOINSTR_VALIDATION 1058 config HAVE_NOINSTR_VALIDATION
1228 bool 1059 bool
1229 1060
1230 config HAVE_UACCESS_VALIDATION 1061 config HAVE_UACCESS_VALIDATION
1231 bool 1062 bool
1232 select OBJTOOL 1063 select OBJTOOL
1233 1064
1234 config HAVE_STACK_VALIDATION 1065 config HAVE_STACK_VALIDATION
1235 bool 1066 bool
1236 help 1067 help
1237 Architecture supports objtool compi 1068 Architecture supports objtool compile-time frame pointer rule
1238 validation. 1069 validation.
1239 1070
1240 config HAVE_RELIABLE_STACKTRACE 1071 config HAVE_RELIABLE_STACKTRACE
1241 bool 1072 bool
1242 help 1073 help
1243 Architecture has either save_stack_ 1074 Architecture has either save_stack_trace_tsk_reliable() or
1244 arch_stack_walk_reliable() function 1075 arch_stack_walk_reliable() function which only returns a stack trace
1245 if it can guarantee the trace is re 1076 if it can guarantee the trace is reliable.
1246 1077
1247 config HAVE_ARCH_HASH 1078 config HAVE_ARCH_HASH
1248 bool 1079 bool
1249 default n 1080 default n
1250 help 1081 help
1251 If this is set, the architecture pr 1082 If this is set, the architecture provides an <asm/hash.h>
1252 file which provides platform-specif 1083 file which provides platform-specific implementations of some
1253 functions in <linux/hash.h> or fs/n 1084 functions in <linux/hash.h> or fs/namei.c.
1254 1085
1255 config HAVE_ARCH_NVRAM_OPS 1086 config HAVE_ARCH_NVRAM_OPS
1256 bool 1087 bool
1257 1088
1258 config ISA_BUS_API 1089 config ISA_BUS_API
1259 def_bool ISA 1090 def_bool ISA
1260 1091
1261 # 1092 #
1262 # ABI hall of shame 1093 # ABI hall of shame
1263 # 1094 #
1264 config CLONE_BACKWARDS 1095 config CLONE_BACKWARDS
1265 bool 1096 bool
1266 help 1097 help
1267 Architecture has tls passed as the 1098 Architecture has tls passed as the 4th argument of clone(2),
1268 not the 5th one. 1099 not the 5th one.
1269 1100
1270 config CLONE_BACKWARDS2 1101 config CLONE_BACKWARDS2
1271 bool 1102 bool
1272 help 1103 help
1273 Architecture has the first two argu 1104 Architecture has the first two arguments of clone(2) swapped.
1274 1105
1275 config CLONE_BACKWARDS3 1106 config CLONE_BACKWARDS3
1276 bool 1107 bool
1277 help 1108 help
1278 Architecture has tls passed as the 1109 Architecture has tls passed as the 3rd argument of clone(2),
1279 not the 5th one. 1110 not the 5th one.
1280 1111
1281 config ODD_RT_SIGACTION 1112 config ODD_RT_SIGACTION
1282 bool 1113 bool
1283 help 1114 help
1284 Architecture has unusual rt_sigacti 1115 Architecture has unusual rt_sigaction(2) arguments
1285 1116
1286 config OLD_SIGSUSPEND 1117 config OLD_SIGSUSPEND
1287 bool 1118 bool
1288 help 1119 help
1289 Architecture has old sigsuspend(2) 1120 Architecture has old sigsuspend(2) syscall, of one-argument variety
1290 1121
1291 config OLD_SIGSUSPEND3 1122 config OLD_SIGSUSPEND3
1292 bool 1123 bool
1293 help 1124 help
1294 Even weirder antique ABI - three-ar 1125 Even weirder antique ABI - three-argument sigsuspend(2)
1295 1126
1296 config OLD_SIGACTION 1127 config OLD_SIGACTION
1297 bool 1128 bool
1298 help 1129 help
1299 Architecture has old sigaction(2) s 1130 Architecture has old sigaction(2) syscall. Nope, not the same
1300 as OLD_SIGSUSPEND | OLD_SIGSUSPEND3 1131 as OLD_SIGSUSPEND | OLD_SIGSUSPEND3 - alpha has sigsuspend(2),
1301 but fairly different variant of sig 1132 but fairly different variant of sigaction(2), thanks to OSF/1
1302 compatibility... 1133 compatibility...
1303 1134
1304 config COMPAT_OLD_SIGACTION 1135 config COMPAT_OLD_SIGACTION
1305 bool 1136 bool
1306 1137
1307 config COMPAT_32BIT_TIME 1138 config COMPAT_32BIT_TIME
1308 bool "Provide system calls for 32-bit 1139 bool "Provide system calls for 32-bit time_t"
1309 default !64BIT || COMPAT 1140 default !64BIT || COMPAT
1310 help 1141 help
1311 This enables 32 bit time_t support 1142 This enables 32 bit time_t support in addition to 64 bit time_t support.
1312 This is relevant on all 32-bit arch 1143 This is relevant on all 32-bit architectures, and 64-bit architectures
1313 as part of compat syscall handling. 1144 as part of compat syscall handling.
1314 1145
1315 config ARCH_NO_PREEMPT 1146 config ARCH_NO_PREEMPT
1316 bool 1147 bool
1317 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
1318 config ARCH_SUPPORTS_RT 1156 config ARCH_SUPPORTS_RT
1319 bool 1157 bool
1320 1158
1321 config CPU_NO_EFFICIENT_FFS 1159 config CPU_NO_EFFICIENT_FFS
1322 def_bool n 1160 def_bool n
1323 1161
1324 config HAVE_ARCH_VMAP_STACK 1162 config HAVE_ARCH_VMAP_STACK
1325 def_bool n 1163 def_bool n
1326 help 1164 help
1327 An arch should select this symbol i 1165 An arch should select this symbol if it can support kernel stacks
1328 in vmalloc space. This means: 1166 in vmalloc space. This means:
1329 1167
1330 - vmalloc space must be large enoug 1168 - vmalloc space must be large enough to hold many kernel stacks.
1331 This may rule out many 32-bit arc 1169 This may rule out many 32-bit architectures.
1332 1170
1333 - Stacks in vmalloc space need to w 1171 - Stacks in vmalloc space need to work reliably. For example, if
1334 vmap page tables are created on d 1172 vmap page tables are created on demand, either this mechanism
1335 needs to work while the stack poi 1173 needs to work while the stack points to a virtual address with
1336 unpopulated page tables or arch c 1174 unpopulated page tables or arch code (switch_to() and switch_mm(),
1337 most likely) needs to ensure that 1175 most likely) needs to ensure that the stack's page table entries
1338 are populated before running on a 1176 are populated before running on a possibly unpopulated stack.
1339 1177
1340 - If the stack overflows into a gua 1178 - If the stack overflows into a guard page, something reasonable
1341 should happen. The definition of 1179 should happen. The definition of "reasonable" is flexible, but
1342 instantly rebooting without loggi 1180 instantly rebooting without logging anything would be unfriendly.
1343 1181
1344 config VMAP_STACK 1182 config VMAP_STACK
1345 default y 1183 default y
1346 bool "Use a virtually-mapped stack" 1184 bool "Use a virtually-mapped stack"
1347 depends on HAVE_ARCH_VMAP_STACK 1185 depends on HAVE_ARCH_VMAP_STACK
1348 depends on !KASAN || KASAN_HW_TAGS || 1186 depends on !KASAN || KASAN_HW_TAGS || KASAN_VMALLOC
1349 help 1187 help
1350 Enable this if you want the use vir 1188 Enable this if you want the use virtually-mapped kernel stacks
1351 with guard pages. This causes kern 1189 with guard pages. This causes kernel stack overflows to be
1352 caught immediately rather than caus 1190 caught immediately rather than causing difficult-to-diagnose
1353 corruption. 1191 corruption.
1354 1192
1355 To use this with software KASAN mod 1193 To use this with software KASAN modes, the architecture must support
1356 backing virtual mappings with real 1194 backing virtual mappings with real shadow memory, and KASAN_VMALLOC
1357 must be enabled. 1195 must be enabled.
1358 1196
1359 config HAVE_ARCH_RANDOMIZE_KSTACK_OFFSET 1197 config HAVE_ARCH_RANDOMIZE_KSTACK_OFFSET
1360 def_bool n 1198 def_bool n
1361 help 1199 help
1362 An arch should select this symbol i 1200 An arch should select this symbol if it can support kernel stack
1363 offset randomization with calls to 1201 offset randomization with calls to add_random_kstack_offset()
1364 during syscall entry and choose_ran 1202 during syscall entry and choose_random_kstack_offset() during
1365 syscall exit. Careful removal of -f 1203 syscall exit. Careful removal of -fstack-protector-strong and
1366 -fstack-protector should also be ap 1204 -fstack-protector should also be applied to the entry code and
1367 closely examined, as the artificial 1205 closely examined, as the artificial stack bump looks like an array
1368 to the compiler, so it will attempt 1206 to the compiler, so it will attempt to add canary checks regardless
1369 of the static branch state. 1207 of the static branch state.
1370 1208
1371 config RANDOMIZE_KSTACK_OFFSET 1209 config RANDOMIZE_KSTACK_OFFSET
1372 bool "Support for randomizing kernel 1210 bool "Support for randomizing kernel stack offset on syscall entry" if EXPERT
1373 default y 1211 default y
1374 depends on HAVE_ARCH_RANDOMIZE_KSTACK 1212 depends on HAVE_ARCH_RANDOMIZE_KSTACK_OFFSET
1375 depends on INIT_STACK_NONE || !CC_IS_ 1213 depends on INIT_STACK_NONE || !CC_IS_CLANG || CLANG_VERSION >= 140000
1376 help 1214 help
1377 The kernel stack offset can be rand 1215 The kernel stack offset can be randomized (after pt_regs) by
1378 roughly 5 bits of entropy, frustrat 1216 roughly 5 bits of entropy, frustrating memory corruption
1379 attacks that depend on stack addres 1217 attacks that depend on stack address determinism or
1380 cross-syscall address exposures. 1218 cross-syscall address exposures.
1381 1219
1382 The feature is controlled via the " 1220 The feature is controlled via the "randomize_kstack_offset=on/off"
1383 kernel boot param, and if turned of 1221 kernel boot param, and if turned off has zero overhead due to its use
1384 of static branches (see JUMP_LABEL) 1222 of static branches (see JUMP_LABEL).
1385 1223
1386 If unsure, say Y. 1224 If unsure, say Y.
1387 1225
1388 config RANDOMIZE_KSTACK_OFFSET_DEFAULT 1226 config RANDOMIZE_KSTACK_OFFSET_DEFAULT
1389 bool "Default state of kernel stack o 1227 bool "Default state of kernel stack offset randomization"
1390 depends on RANDOMIZE_KSTACK_OFFSET 1228 depends on RANDOMIZE_KSTACK_OFFSET
1391 help 1229 help
1392 Kernel stack offset randomization i 1230 Kernel stack offset randomization is controlled by kernel boot param
1393 "randomize_kstack_offset=on/off", a 1231 "randomize_kstack_offset=on/off", and this config chooses the default
1394 boot state. 1232 boot state.
1395 1233
1396 config ARCH_OPTIONAL_KERNEL_RWX 1234 config ARCH_OPTIONAL_KERNEL_RWX
1397 def_bool n 1235 def_bool n
1398 1236
1399 config ARCH_OPTIONAL_KERNEL_RWX_DEFAULT 1237 config ARCH_OPTIONAL_KERNEL_RWX_DEFAULT
1400 def_bool n 1238 def_bool n
1401 1239
1402 config ARCH_HAS_STRICT_KERNEL_RWX 1240 config ARCH_HAS_STRICT_KERNEL_RWX
1403 def_bool n 1241 def_bool n
1404 1242
1405 config STRICT_KERNEL_RWX 1243 config STRICT_KERNEL_RWX
1406 bool "Make kernel text and rodata rea 1244 bool "Make kernel text and rodata read-only" if ARCH_OPTIONAL_KERNEL_RWX
1407 depends on ARCH_HAS_STRICT_KERNEL_RWX 1245 depends on ARCH_HAS_STRICT_KERNEL_RWX
1408 default !ARCH_OPTIONAL_KERNEL_RWX || 1246 default !ARCH_OPTIONAL_KERNEL_RWX || ARCH_OPTIONAL_KERNEL_RWX_DEFAULT
1409 help 1247 help
1410 If this is set, kernel text and rod 1248 If this is set, kernel text and rodata memory will be made read-only,
1411 and non-text memory will be made no 1249 and non-text memory will be made non-executable. This provides
1412 protection against certain security 1250 protection against certain security exploits (e.g. executing the heap
1413 or modifying text) 1251 or modifying text)
1414 1252
1415 These features are considered stand 1253 These features are considered standard security practice these days.
1416 You should say Y here in almost all 1254 You should say Y here in almost all cases.
1417 1255
1418 config ARCH_HAS_STRICT_MODULE_RWX 1256 config ARCH_HAS_STRICT_MODULE_RWX
1419 def_bool n 1257 def_bool n
1420 1258
1421 config STRICT_MODULE_RWX 1259 config STRICT_MODULE_RWX
1422 bool "Set loadable kernel module data 1260 bool "Set loadable kernel module data as NX and text as RO" if ARCH_OPTIONAL_KERNEL_RWX
1423 depends on ARCH_HAS_STRICT_MODULE_RWX 1261 depends on ARCH_HAS_STRICT_MODULE_RWX && MODULES
1424 default !ARCH_OPTIONAL_KERNEL_RWX || 1262 default !ARCH_OPTIONAL_KERNEL_RWX || ARCH_OPTIONAL_KERNEL_RWX_DEFAULT
1425 help 1263 help
1426 If this is set, module text and rod 1264 If this is set, module text and rodata memory will be made read-only,
1427 and non-text memory will be made no 1265 and non-text memory will be made non-executable. This provides
1428 protection against certain security 1266 protection against certain security exploits (e.g. writing to text)
1429 1267
1430 # select if the architecture provides an asm/ 1268 # select if the architecture provides an asm/dma-direct.h header
1431 config ARCH_HAS_PHYS_TO_DMA 1269 config ARCH_HAS_PHYS_TO_DMA
1432 bool 1270 bool
1433 1271
1434 config HAVE_ARCH_COMPILER_H 1272 config HAVE_ARCH_COMPILER_H
1435 bool 1273 bool
1436 help 1274 help
1437 An architecture can select this if 1275 An architecture can select this if it provides an
1438 asm/compiler.h header that should b 1276 asm/compiler.h header that should be included after
1439 linux/compiler-*.h in order to over 1277 linux/compiler-*.h in order to override macro definitions that those
1440 headers generally provide. 1278 headers generally provide.
1441 1279
1442 config HAVE_ARCH_PREL32_RELOCATIONS 1280 config HAVE_ARCH_PREL32_RELOCATIONS
1443 bool 1281 bool
1444 help 1282 help
1445 May be selected by an architecture 1283 May be selected by an architecture if it supports place-relative
1446 32-bit relocations, both in the too 1284 32-bit relocations, both in the toolchain and in the module loader,
1447 in which case relative references c 1285 in which case relative references can be used in special sections
1448 for PCI fixup, initcalls etc which 1286 for PCI fixup, initcalls etc which are only half the size on 64 bit
1449 architectures, and don't require ru 1287 architectures, and don't require runtime relocation on relocatable
1450 kernels. 1288 kernels.
1451 1289
1452 config ARCH_USE_MEMREMAP_PROT 1290 config ARCH_USE_MEMREMAP_PROT
1453 bool 1291 bool
1454 1292
1455 config LOCK_EVENT_COUNTS 1293 config LOCK_EVENT_COUNTS
1456 bool "Locking event counts collection 1294 bool "Locking event counts collection"
1457 depends on DEBUG_FS 1295 depends on DEBUG_FS
1458 help 1296 help
1459 Enable light-weight counting of var 1297 Enable light-weight counting of various locking related events
1460 in the system with minimal performa 1298 in the system with minimal performance impact. This reduces
1461 the chance of application behavior 1299 the chance of application behavior change because of timing
1462 differences. The counts are reporte 1300 differences. The counts are reported via debugfs.
1463 1301
1464 # Select if the architecture has support for 1302 # Select if the architecture has support for applying RELR relocations.
1465 config ARCH_HAS_RELR 1303 config ARCH_HAS_RELR
1466 bool 1304 bool
1467 1305
1468 config RELR 1306 config RELR
1469 bool "Use RELR relocation packing" 1307 bool "Use RELR relocation packing"
1470 depends on ARCH_HAS_RELR && TOOLS_SUP 1308 depends on ARCH_HAS_RELR && TOOLS_SUPPORT_RELR
1471 default y 1309 default y
1472 help 1310 help
1473 Store the kernel's dynamic relocati 1311 Store the kernel's dynamic relocations in the RELR relocation packing
1474 format. Requires a compatible linke 1312 format. Requires a compatible linker (LLD supports this feature), as
1475 well as compatible NM and OBJCOPY u 1313 well as compatible NM and OBJCOPY utilities (llvm-nm and llvm-objcopy
1476 are compatible). 1314 are compatible).
1477 1315
1478 config ARCH_HAS_MEM_ENCRYPT 1316 config ARCH_HAS_MEM_ENCRYPT
1479 bool 1317 bool
1480 1318
1481 config ARCH_HAS_CC_PLATFORM 1319 config ARCH_HAS_CC_PLATFORM
1482 bool 1320 bool
1483 1321
1484 config HAVE_SPARSE_SYSCALL_NR 1322 config HAVE_SPARSE_SYSCALL_NR
1485 bool !! 1323 bool
1486 help !! 1324 help
1487 An architecture should select this !! 1325 An architecture should select this if its syscall numbering is sparse
1488 to save space. For example, MIPS ar 1326 to save space. For example, MIPS architecture has a syscall array with
1489 entries at 4000, 5000 and 6000 loca 1327 entries at 4000, 5000 and 6000 locations. This option turns on syscall
1490 related optimizations for a given a 1328 related optimizations for a given architecture.
1491 1329
1492 config ARCH_HAS_VDSO_DATA 1330 config ARCH_HAS_VDSO_DATA
1493 bool 1331 bool
1494 1332
1495 config HAVE_STATIC_CALL 1333 config HAVE_STATIC_CALL
1496 bool 1334 bool
1497 1335
1498 config HAVE_STATIC_CALL_INLINE 1336 config HAVE_STATIC_CALL_INLINE
1499 bool 1337 bool
1500 depends on HAVE_STATIC_CALL 1338 depends on HAVE_STATIC_CALL
1501 select OBJTOOL 1339 select OBJTOOL
1502 1340
1503 config HAVE_PREEMPT_DYNAMIC 1341 config HAVE_PREEMPT_DYNAMIC
1504 bool 1342 bool
1505 1343
1506 config HAVE_PREEMPT_DYNAMIC_CALL 1344 config HAVE_PREEMPT_DYNAMIC_CALL
1507 bool 1345 bool
1508 depends on HAVE_STATIC_CALL 1346 depends on HAVE_STATIC_CALL
1509 select HAVE_PREEMPT_DYNAMIC 1347 select HAVE_PREEMPT_DYNAMIC
1510 help 1348 help
1511 An architecture should select this !! 1349 An architecture should select this if it can handle the preemption
1512 model being selected at boot time u !! 1350 model being selected at boot time using static calls.
1513 1351
1514 Where an architecture selects HAVE_ !! 1352 Where an architecture selects HAVE_STATIC_CALL_INLINE, any call to a
1515 preemption function will be patched !! 1353 preemption function will be patched directly.
1516 1354
1517 Where an architecture does not sele !! 1355 Where an architecture does not select HAVE_STATIC_CALL_INLINE, any
1518 call to a preemption function will !! 1356 call to a preemption function will go through a trampoline, and the
1519 trampoline will be patched. !! 1357 trampoline will be patched.
1520 1358
1521 It is strongly advised to support i !! 1359 It is strongly advised to support inline static call to avoid any
1522 overhead. !! 1360 overhead.
1523 1361
1524 config HAVE_PREEMPT_DYNAMIC_KEY 1362 config HAVE_PREEMPT_DYNAMIC_KEY
1525 bool 1363 bool
1526 depends on HAVE_ARCH_JUMP_LABEL !! 1364 depends on HAVE_ARCH_JUMP_LABEL && CC_HAS_ASM_GOTO
1527 select HAVE_PREEMPT_DYNAMIC 1365 select HAVE_PREEMPT_DYNAMIC
1528 help 1366 help
1529 An architecture should select this !! 1367 An architecture should select this if it can handle the preemption
1530 model being selected at boot time u !! 1368 model being selected at boot time using static keys.
1531 1369
1532 Each preemption function will be gi !! 1370 Each preemption function will be given an early return based on a
1533 static key. This should have slight !! 1371 static key. This should have slightly lower overhead than non-inline
1534 static calls, as this effectively i !! 1372 static calls, as this effectively inlines each trampoline into the
1535 start of its callee. This may avoid !! 1373 start of its callee. This may avoid redundant work, and may
1536 integrate better with CFI schemes. !! 1374 integrate better with CFI schemes.
1537 1375
1538 This will have greater overhead tha !! 1376 This will have greater overhead than using inline static calls as
1539 the call to the preemption function !! 1377 the call to the preemption function cannot be entirely elided.
1540 1378
1541 config ARCH_WANT_LD_ORPHAN_WARN 1379 config ARCH_WANT_LD_ORPHAN_WARN
1542 bool 1380 bool
1543 help 1381 help
1544 An arch should select this symbol o 1382 An arch should select this symbol once all linker sections are explicitly
1545 included, size-asserted, or discard 1383 included, size-asserted, or discarded in the linker scripts. This is
1546 important because we never want exp 1384 important because we never want expected sections to be placed heuristically
1547 by the linker, since the locations 1385 by the linker, since the locations of such sections can change between linker
1548 versions. 1386 versions.
1549 1387
1550 config HAVE_ARCH_PFN_VALID 1388 config HAVE_ARCH_PFN_VALID
1551 bool 1389 bool
1552 1390
1553 config ARCH_SUPPORTS_DEBUG_PAGEALLOC 1391 config ARCH_SUPPORTS_DEBUG_PAGEALLOC
1554 bool 1392 bool
1555 1393
1556 config ARCH_SUPPORTS_PAGE_TABLE_CHECK 1394 config ARCH_SUPPORTS_PAGE_TABLE_CHECK
1557 bool 1395 bool
1558 1396
1559 config ARCH_SPLIT_ARG64 1397 config ARCH_SPLIT_ARG64
1560 bool 1398 bool
1561 help 1399 help
1562 If a 32-bit architecture requires 6 !! 1400 If a 32-bit architecture requires 64-bit arguments to be split into
1563 pairs of 32-bit arguments, select t !! 1401 pairs of 32-bit arguments, select this option.
1564 1402
1565 config ARCH_HAS_ELFCORE_COMPAT 1403 config ARCH_HAS_ELFCORE_COMPAT
1566 bool 1404 bool
1567 1405
1568 config ARCH_HAS_PARANOID_L1D_FLUSH 1406 config ARCH_HAS_PARANOID_L1D_FLUSH
1569 bool 1407 bool
1570 1408
1571 config ARCH_HAVE_TRACE_MMIO_ACCESS <<
1572 bool <<
1573 <<
1574 config DYNAMIC_SIGFRAME 1409 config DYNAMIC_SIGFRAME
1575 bool 1410 bool
1576 1411
1577 # Select, if arch has a named attribute group 1412 # Select, if arch has a named attribute group bound to NUMA device nodes.
1578 config HAVE_ARCH_NODE_DEV_GROUP 1413 config HAVE_ARCH_NODE_DEV_GROUP
1579 bool 1414 bool
1580 1415
1581 config ARCH_HAS_HW_PTE_YOUNG <<
1582 bool <<
1583 help <<
1584 Architectures that select this opti <<
1585 accessed bit in PTE entries when us <<
1586 translations. Architectures that re <<
1587 this option and override arch_has_h <<
1588 <<
1589 config ARCH_HAS_NONLEAF_PMD_YOUNG <<
1590 bool <<
1591 help <<
1592 Architectures that select this opti <<
1593 accessed bit in non-leaf PMD entrie <<
1594 address translations. Page table wa <<
1595 may use this capability to reduce t <<
1596 <<
1597 config ARCH_HAS_KERNEL_FPU_SUPPORT <<
1598 bool <<
1599 help <<
1600 Architectures that select this opti <<
1601 the kernel, as described in Documen <<
1602 <<
1603 source "kernel/gcov/Kconfig" 1416 source "kernel/gcov/Kconfig"
1604 1417
1605 source "scripts/gcc-plugins/Kconfig" 1418 source "scripts/gcc-plugins/Kconfig"
1606 <<
1607 config FUNCTION_ALIGNMENT_4B <<
1608 bool <<
1609 <<
1610 config FUNCTION_ALIGNMENT_8B <<
1611 bool <<
1612 <<
1613 config FUNCTION_ALIGNMENT_16B <<
1614 bool <<
1615 <<
1616 config FUNCTION_ALIGNMENT_32B <<
1617 bool <<
1618 <<
1619 config FUNCTION_ALIGNMENT_64B <<
1620 bool <<
1621 <<
1622 config FUNCTION_ALIGNMENT <<
1623 int <<
1624 default 64 if FUNCTION_ALIGNMENT_64B <<
1625 default 32 if FUNCTION_ALIGNMENT_32B <<
1626 default 16 if FUNCTION_ALIGNMENT_16B <<
1627 default 8 if FUNCTION_ALIGNMENT_8B <<
1628 default 4 if FUNCTION_ALIGNMENT_4B <<
1629 default 0 <<
1630 <<
1631 config CC_HAS_MIN_FUNCTION_ALIGNMENT <<
1632 # Detect availability of the GCC opti <<
1633 # guarantees minimal alignment for al <<
1634 # -falign-functions which the compile <<
1635 def_bool $(cc-option, -fmin-function- <<
1636 <<
1637 config CC_HAS_SANE_FUNCTION_ALIGNMENT <<
1638 # Set if the guaranteed alignment wit <<
1639 # available or extra care is required <<
1640 # strict alignment always, even with <<
1641 def_bool CC_HAS_MIN_FUNCTION_ALIGNMEN <<
1642 <<
1643 config ARCH_NEED_CMPXCHG_1_EMU <<
1644 bool <<
1645 1419
1646 endmenu 1420 endmenu
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