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 <<
34 <<
35 # Selected by HOTPLUG_CORE_SYNC_DEAD or HOTPLU <<
36 config HOTPLUG_CORE_SYNC <<
37 bool 15 bool
38 16
39 # Basic CPU dead synchronization selected by a !! 17 config KEXEC_CORE
40 config HOTPLUG_CORE_SYNC_DEAD !! 18 select CRASH_CORE
41 bool 19 bool
42 select HOTPLUG_CORE_SYNC <<
43 20
44 # Full CPU synchronization with alive state se !! 21 config KEXEC_ELF
45 config HOTPLUG_CORE_SYNC_FULL <<
46 bool 22 bool
47 select HOTPLUG_CORE_SYNC_DEAD if HOTPL <<
48 select HOTPLUG_CORE_SYNC <<
49 23
50 config HOTPLUG_SPLIT_STARTUP !! 24 config HAVE_IMA_KEXEC
51 bool 25 bool
52 select HOTPLUG_CORE_SYNC_FULL <<
53 26
54 config HOTPLUG_PARALLEL !! 27 config HOTPLUG_SMT
55 bool 28 bool
56 select HOTPLUG_SPLIT_STARTUP <<
57 29
58 config GENERIC_ENTRY 30 config GENERIC_ENTRY
59 bool !! 31 bool
60 32
61 config KPROBES 33 config KPROBES
62 bool "Kprobes" 34 bool "Kprobes"
>> 35 depends on MODULES
63 depends on HAVE_KPROBES 36 depends on HAVE_KPROBES
64 select KALLSYMS 37 select KALLSYMS
65 select EXECMEM <<
66 select NEED_TASKS_RCU <<
67 help 38 help
68 Kprobes allows you to trap at almost 39 Kprobes allows you to trap at almost any kernel address and
69 execute a callback function. regist 40 execute a callback function. register_kprobe() establishes
70 a probepoint and specifies the callb 41 a probepoint and specifies the callback. Kprobes is useful
71 for kernel debugging, non-intrusive 42 for kernel debugging, non-intrusive instrumentation and testing.
72 If in doubt, say "N". 43 If in doubt, say "N".
73 44
74 config JUMP_LABEL 45 config JUMP_LABEL
75 bool "Optimize very unlikely/likely br 46 bool "Optimize very unlikely/likely branches"
76 depends on HAVE_ARCH_JUMP_LABEL 47 depends on HAVE_ARCH_JUMP_LABEL
77 select OBJTOOL if HAVE_JUMP_LABEL_HACK !! 48 depends on CC_HAS_ASM_GOTO
78 help 49 help
79 This option enables a transparent br !! 50 This option enables a transparent branch optimization that
80 makes certain almost-always-true or !! 51 makes certain almost-always-true or almost-always-false branch
81 conditions even cheaper to execute w !! 52 conditions even cheaper to execute within the kernel.
82 !! 53
83 Certain performance-sensitive kernel !! 54 Certain performance-sensitive kernel code, such as trace points,
84 scheduler functionality, networking !! 55 scheduler functionality, networking code and KVM have such
85 branches and include support for thi !! 56 branches and include support for this optimization technique.
86 !! 57
87 If it is detected that the compiler !! 58 If it is detected that the compiler has support for "asm goto",
88 the kernel will compile such branche !! 59 the kernel will compile such branches with just a nop
89 instruction. When the condition flag !! 60 instruction. When the condition flag is toggled to true, the
90 nop will be converted to a jump inst !! 61 nop will be converted to a jump instruction to execute the
91 conditional block of instructions. !! 62 conditional block of instructions.
92 !! 63
93 This technique lowers overhead and s !! 64 This technique lowers overhead and stress on the branch prediction
94 of the processor and generally makes !! 65 of the processor and generally makes the kernel faster. The update
95 of the condition is slower, but thos !! 66 of the condition is slower, but those are always very rare.
96 67
97 ( On 32-bit x86, the necessary optio !! 68 ( On 32-bit x86, the necessary options added to the compiler
98 flags may increase the size of the !! 69 flags may increase the size of the kernel slightly. )
99 70
100 config STATIC_KEYS_SELFTEST 71 config STATIC_KEYS_SELFTEST
101 bool "Static key selftest" 72 bool "Static key selftest"
102 depends on JUMP_LABEL 73 depends on JUMP_LABEL
103 help 74 help
104 Boot time self-test of the branch pa 75 Boot time self-test of the branch patching code.
105 76
106 config STATIC_CALL_SELFTEST 77 config STATIC_CALL_SELFTEST
107 bool "Static call selftest" 78 bool "Static call selftest"
108 depends on HAVE_STATIC_CALL 79 depends on HAVE_STATIC_CALL
109 help 80 help
110 Boot time self-test of the call patc 81 Boot time self-test of the call patching code.
111 82
112 config OPTPROBES 83 config OPTPROBES
113 def_bool y 84 def_bool y
114 depends on KPROBES && HAVE_OPTPROBES 85 depends on KPROBES && HAVE_OPTPROBES
115 select NEED_TASKS_RCU !! 86 select TASKS_RCU if PREEMPTION
116 87
117 config KPROBES_ON_FTRACE 88 config KPROBES_ON_FTRACE
118 def_bool y 89 def_bool y
119 depends on KPROBES && HAVE_KPROBES_ON_ 90 depends on KPROBES && HAVE_KPROBES_ON_FTRACE
120 depends on DYNAMIC_FTRACE_WITH_REGS 91 depends on DYNAMIC_FTRACE_WITH_REGS
121 help 92 help
122 If function tracer is enabled and th !! 93 If function tracer is enabled and the arch supports full
123 passing of pt_regs to function traci !! 94 passing of pt_regs to function tracing, then kprobes can
124 optimize on top of function tracing. !! 95 optimize on top of function tracing.
125 96
126 config UPROBES 97 config UPROBES
127 def_bool n 98 def_bool n
128 depends on ARCH_SUPPORTS_UPROBES 99 depends on ARCH_SUPPORTS_UPROBES
129 help 100 help
130 Uprobes is the user-space counterpar 101 Uprobes is the user-space counterpart to kprobes: they
131 enable instrumentation applications 102 enable instrumentation applications (such as 'perf probe')
132 to establish unintrusive probes in u 103 to establish unintrusive probes in user-space binaries and
133 libraries, by executing handler func 104 libraries, by executing handler functions when the probes
134 are hit by user-space applications. 105 are hit by user-space applications.
135 106
136 ( These probes come in the form of s 107 ( These probes come in the form of single-byte breakpoints,
137 managed by the kernel and kept tra 108 managed by the kernel and kept transparent to the probed
138 application. ) 109 application. )
139 110
140 config HAVE_64BIT_ALIGNED_ACCESS 111 config HAVE_64BIT_ALIGNED_ACCESS
141 def_bool 64BIT && !HAVE_EFFICIENT_UNAL 112 def_bool 64BIT && !HAVE_EFFICIENT_UNALIGNED_ACCESS
142 help 113 help
143 Some architectures require 64 bit ac 114 Some architectures require 64 bit accesses to be 64 bit
144 aligned, which also requires structs 115 aligned, which also requires structs containing 64 bit values
145 to be 64 bit aligned too. This inclu 116 to be 64 bit aligned too. This includes some 32 bit
146 architectures which can do 64 bit ac 117 architectures which can do 64 bit accesses, as well as 64 bit
147 architectures without unaligned acce 118 architectures without unaligned access.
148 119
149 This symbol should be selected by an 120 This symbol should be selected by an architecture if 64 bit
150 accesses are required to be 64 bit a 121 accesses are required to be 64 bit aligned in this way even
151 though it is not a 64 bit architectu 122 though it is not a 64 bit architecture.
152 123
153 See Documentation/core-api/unaligned 124 See Documentation/core-api/unaligned-memory-access.rst for
154 more information on the topic of una 125 more information on the topic of unaligned memory accesses.
155 126
156 config HAVE_EFFICIENT_UNALIGNED_ACCESS 127 config HAVE_EFFICIENT_UNALIGNED_ACCESS
157 bool 128 bool
158 help 129 help
159 Some architectures are unable to per 130 Some architectures are unable to perform unaligned accesses
160 without the use of get_unaligned/put 131 without the use of get_unaligned/put_unaligned. Others are
161 unable to perform such accesses effi 132 unable to perform such accesses efficiently (e.g. trap on
162 unaligned access and require fixing 133 unaligned access and require fixing it up in the exception
163 handler.) 134 handler.)
164 135
165 This symbol should be selected by an 136 This symbol should be selected by an architecture if it can
166 perform unaligned accesses efficient 137 perform unaligned accesses efficiently to allow different
167 code paths to be selected for these 138 code paths to be selected for these cases. Some network
168 drivers, for example, could opt to n 139 drivers, for example, could opt to not fix up alignment
169 problems with received packets if do 140 problems with received packets if doing so would not help
170 much. 141 much.
171 142
172 See Documentation/core-api/unaligned 143 See Documentation/core-api/unaligned-memory-access.rst for more
173 information on the topic of unaligne 144 information on the topic of unaligned memory accesses.
174 145
175 config ARCH_USE_BUILTIN_BSWAP 146 config ARCH_USE_BUILTIN_BSWAP
176 bool 147 bool
177 help 148 help
178 Modern versions of GCC (since 4.4) h !! 149 Modern versions of GCC (since 4.4) have builtin functions
179 for handling byte-swapping. Using th !! 150 for handling byte-swapping. Using these, instead of the old
180 inline assembler that the architectu !! 151 inline assembler that the architecture code provides in the
181 __arch_bswapXX() macros, allows the !! 152 __arch_bswapXX() macros, allows the compiler to see what's
182 happening and offers more opportunit !! 153 happening and offers more opportunity for optimisation. In
183 particular, the compiler will be abl !! 154 particular, the compiler will be able to combine the byteswap
184 with a nearby load or store and use !! 155 with a nearby load or store and use load-and-swap or
185 store-and-swap instructions if the a !! 156 store-and-swap instructions if the architecture has them. It
186 should almost *never* result in code !! 157 should almost *never* result in code which is worse than the
187 hand-coded assembler in <asm/swab.h> !! 158 hand-coded assembler in <asm/swab.h>. But just in case it
188 does, the use of the builtins is opt !! 159 does, the use of the builtins is optional.
189 !! 160
190 Any architecture with load-and-swap !! 161 Any architecture with load-and-swap or store-and-swap
191 instructions should set this. And it !! 162 instructions should set this. And it shouldn't hurt to set it
192 on architectures that don't have suc !! 163 on architectures that don't have such instructions.
193 164
194 config KRETPROBES 165 config KRETPROBES
195 def_bool y 166 def_bool y
196 depends on KPROBES && (HAVE_KRETPROBES 167 depends on KPROBES && (HAVE_KRETPROBES || HAVE_RETHOOK)
197 168
198 config KRETPROBE_ON_RETHOOK 169 config KRETPROBE_ON_RETHOOK
199 def_bool y 170 def_bool y
200 depends on HAVE_RETHOOK 171 depends on HAVE_RETHOOK
201 depends on KRETPROBES 172 depends on KRETPROBES
202 select RETHOOK 173 select RETHOOK
203 174
204 config USER_RETURN_NOTIFIER 175 config USER_RETURN_NOTIFIER
205 bool 176 bool
206 depends on HAVE_USER_RETURN_NOTIFIER 177 depends on HAVE_USER_RETURN_NOTIFIER
207 help 178 help
208 Provide a kernel-internal notificati 179 Provide a kernel-internal notification when a cpu is about to
209 switch to user mode. 180 switch to user mode.
210 181
211 config HAVE_IOREMAP_PROT 182 config HAVE_IOREMAP_PROT
212 bool 183 bool
213 184
214 config HAVE_KPROBES 185 config HAVE_KPROBES
215 bool 186 bool
216 187
217 config HAVE_KRETPROBES 188 config HAVE_KRETPROBES
218 bool 189 bool
219 190
220 config HAVE_OPTPROBES 191 config HAVE_OPTPROBES
221 bool 192 bool
222 193
223 config HAVE_KPROBES_ON_FTRACE 194 config HAVE_KPROBES_ON_FTRACE
224 bool 195 bool
225 196
226 config ARCH_CORRECT_STACKTRACE_ON_KRETPROBE 197 config ARCH_CORRECT_STACKTRACE_ON_KRETPROBE
227 bool 198 bool
228 help 199 help
229 Since kretprobes modifies return add 200 Since kretprobes modifies return address on the stack, the
230 stacktrace may see the kretprobe tra 201 stacktrace may see the kretprobe trampoline address instead
231 of correct one. If the architecture 202 of correct one. If the architecture stacktrace code and
232 unwinder can adjust such entries, se 203 unwinder can adjust such entries, select this configuration.
233 204
234 config HAVE_FUNCTION_ERROR_INJECTION 205 config HAVE_FUNCTION_ERROR_INJECTION
235 bool 206 bool
236 207
237 config HAVE_NMI 208 config HAVE_NMI
238 bool 209 bool
239 210
240 config HAVE_FUNCTION_DESCRIPTORS 211 config HAVE_FUNCTION_DESCRIPTORS
241 bool 212 bool
242 213
243 config TRACE_IRQFLAGS_SUPPORT 214 config TRACE_IRQFLAGS_SUPPORT
244 bool 215 bool
245 216
246 config TRACE_IRQFLAGS_NMI_SUPPORT 217 config TRACE_IRQFLAGS_NMI_SUPPORT
247 bool 218 bool
248 219
249 # 220 #
250 # An arch should select this if it provides al 221 # An arch should select this if it provides all these things:
251 # 222 #
252 # task_pt_regs() in asm/process 223 # task_pt_regs() in asm/processor.h or asm/ptrace.h
253 # arch_has_single_step() if there is ha 224 # arch_has_single_step() if there is hardware single-step support
254 # arch_has_block_step() if there is ha 225 # arch_has_block_step() if there is hardware block-step support
255 # asm/syscall.h supplying asm- 226 # asm/syscall.h supplying asm-generic/syscall.h interface
256 # linux/regset.h user_regset in 227 # linux/regset.h user_regset interfaces
257 # CORE_DUMP_USE_REGSET #define'd in l 228 # CORE_DUMP_USE_REGSET #define'd in linux/elf.h
258 # TIF_SYSCALL_TRACE calls ptrace_r 229 # TIF_SYSCALL_TRACE calls ptrace_report_syscall_{entry,exit}
259 # TIF_NOTIFY_RESUME calls resume_u 230 # TIF_NOTIFY_RESUME calls resume_user_mode_work()
260 # 231 #
261 config HAVE_ARCH_TRACEHOOK 232 config HAVE_ARCH_TRACEHOOK
262 bool 233 bool
263 234
264 config HAVE_DMA_CONTIGUOUS 235 config HAVE_DMA_CONTIGUOUS
265 bool 236 bool
266 237
267 config GENERIC_SMP_IDLE_THREAD 238 config GENERIC_SMP_IDLE_THREAD
268 bool 239 bool
269 240
270 config GENERIC_IDLE_POLL_SETUP 241 config GENERIC_IDLE_POLL_SETUP
271 bool 242 bool
272 243
273 config ARCH_HAS_FORTIFY_SOURCE 244 config ARCH_HAS_FORTIFY_SOURCE
274 bool 245 bool
275 help 246 help
276 An architecture should select this w 247 An architecture should select this when it can successfully
277 build and run with CONFIG_FORTIFY_SO 248 build and run with CONFIG_FORTIFY_SOURCE.
278 249
279 # 250 #
280 # Select if the arch provides a historic keepi 251 # Select if the arch provides a historic keepinit alias for the retain_initrd
281 # command line option 252 # command line option
282 # 253 #
283 config ARCH_HAS_KEEPINITRD 254 config ARCH_HAS_KEEPINITRD
284 bool 255 bool
285 256
286 # Select if arch has all set_memory_ro/rw/x/nx 257 # Select if arch has all set_memory_ro/rw/x/nx() functions in asm/cacheflush.h
287 config ARCH_HAS_SET_MEMORY 258 config ARCH_HAS_SET_MEMORY
288 bool 259 bool
289 260
290 # Select if arch has all set_direct_map_invali 261 # Select if arch has all set_direct_map_invalid/default() functions
291 config ARCH_HAS_SET_DIRECT_MAP 262 config ARCH_HAS_SET_DIRECT_MAP
292 bool 263 bool
293 264
294 # 265 #
295 # Select if the architecture provides the arch 266 # Select if the architecture provides the arch_dma_set_uncached symbol to
296 # either provide an uncached segment alias for 267 # either provide an uncached segment alias for a DMA allocation, or
297 # to remap the page tables in place. 268 # to remap the page tables in place.
298 # 269 #
299 config ARCH_HAS_DMA_SET_UNCACHED 270 config ARCH_HAS_DMA_SET_UNCACHED
300 bool 271 bool
301 272
302 # 273 #
303 # Select if the architectures provides the arc 274 # Select if the architectures provides the arch_dma_clear_uncached symbol
304 # to undo an in-place page table remap for unc 275 # to undo an in-place page table remap for uncached access.
305 # 276 #
306 config ARCH_HAS_DMA_CLEAR_UNCACHED 277 config ARCH_HAS_DMA_CLEAR_UNCACHED
307 bool 278 bool
308 279
309 config ARCH_HAS_CPU_FINALIZE_INIT !! 280 # Select if arch init_task must go in the __init_task_data section
>> 281 config ARCH_TASK_STRUCT_ON_STACK
310 bool 282 bool
311 283
312 # The architecture has a per-task state that i !! 284 # Select if arch has its private alloc_task_struct() function
313 config ARCH_HAS_CPU_PASID !! 285 config ARCH_TASK_STRUCT_ALLOCATOR
314 bool 286 bool
315 select IOMMU_MM_DATA <<
316 287
317 config HAVE_ARCH_THREAD_STRUCT_WHITELIST 288 config HAVE_ARCH_THREAD_STRUCT_WHITELIST
318 bool 289 bool
>> 290 depends on !ARCH_TASK_STRUCT_ALLOCATOR
319 help 291 help
320 An architecture should select this t 292 An architecture should select this to provide hardened usercopy
321 knowledge about what region of the t 293 knowledge about what region of the thread_struct should be
322 whitelisted for copying to userspace 294 whitelisted for copying to userspace. Normally this is only the
323 FPU registers. Specifically, arch_th 295 FPU registers. Specifically, arch_thread_struct_whitelist()
324 should be implemented. Without this, 296 should be implemented. Without this, the entire thread_struct
325 field in task_struct will be left wh 297 field in task_struct will be left whitelisted.
326 298
>> 299 # Select if arch has its private alloc_thread_stack() function
>> 300 config ARCH_THREAD_STACK_ALLOCATOR
>> 301 bool
>> 302
327 # Select if arch wants to size task_struct dyn 303 # Select if arch wants to size task_struct dynamically via arch_task_struct_size:
328 config ARCH_WANTS_DYNAMIC_TASK_STRUCT 304 config ARCH_WANTS_DYNAMIC_TASK_STRUCT
329 bool 305 bool
330 306
331 config ARCH_WANTS_NO_INSTR 307 config ARCH_WANTS_NO_INSTR
332 bool 308 bool
333 help 309 help
334 An architecture should select this i 310 An architecture should select this if the noinstr macro is being used on
335 functions to denote that the toolcha 311 functions to denote that the toolchain should avoid instrumenting such
336 functions and is required for correc 312 functions and is required for correctness.
337 313
338 config ARCH_32BIT_OFF_T 314 config ARCH_32BIT_OFF_T
339 bool 315 bool
340 depends on !64BIT 316 depends on !64BIT
341 help 317 help
342 All new 32-bit architectures should 318 All new 32-bit architectures should have 64-bit off_t type on
343 userspace side which corresponds to 319 userspace side which corresponds to the loff_t kernel type. This
344 is the requirement for modern ABIs. 320 is the requirement for modern ABIs. Some existing architectures
345 still support 32-bit off_t. This opt 321 still support 32-bit off_t. This option is enabled for all such
346 architectures explicitly. 322 architectures explicitly.
347 323
348 # Selected by 64 bit architectures which have 324 # Selected by 64 bit architectures which have a 32 bit f_tinode in struct ustat
349 config ARCH_32BIT_USTAT_F_TINODE 325 config ARCH_32BIT_USTAT_F_TINODE
350 bool 326 bool
351 327
352 config HAVE_ASM_MODVERSIONS 328 config HAVE_ASM_MODVERSIONS
353 bool 329 bool
354 help 330 help
355 This symbol should be selected by an 331 This symbol should be selected by an architecture if it provides
356 <asm/asm-prototypes.h> to support th 332 <asm/asm-prototypes.h> to support the module versioning for symbols
357 exported from assembly code. 333 exported from assembly code.
358 334
359 config HAVE_REGS_AND_STACK_ACCESS_API 335 config HAVE_REGS_AND_STACK_ACCESS_API
360 bool 336 bool
361 help 337 help
362 This symbol should be selected by an 338 This symbol should be selected by an architecture if it supports
363 the API needed to access registers a 339 the API needed to access registers and stack entries from pt_regs,
364 declared in asm/ptrace.h 340 declared in asm/ptrace.h
365 For example the kprobes-based event 341 For example the kprobes-based event tracer needs this API.
366 342
367 config HAVE_RSEQ 343 config HAVE_RSEQ
368 bool 344 bool
369 depends on HAVE_REGS_AND_STACK_ACCESS_ 345 depends on HAVE_REGS_AND_STACK_ACCESS_API
370 help 346 help
371 This symbol should be selected by an 347 This symbol should be selected by an architecture if it
372 supports an implementation of restar 348 supports an implementation of restartable sequences.
373 349
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 350 config HAVE_FUNCTION_ARG_ACCESS_API
381 bool 351 bool
382 help 352 help
383 This symbol should be selected by an 353 This symbol should be selected by an architecture if it supports
384 the API needed to access function ar 354 the API needed to access function arguments from pt_regs,
385 declared in asm/ptrace.h 355 declared in asm/ptrace.h
386 356
387 config HAVE_HW_BREAKPOINT 357 config HAVE_HW_BREAKPOINT
388 bool 358 bool
389 depends on PERF_EVENTS 359 depends on PERF_EVENTS
390 360
391 config HAVE_MIXED_BREAKPOINTS_REGS 361 config HAVE_MIXED_BREAKPOINTS_REGS
392 bool 362 bool
393 depends on HAVE_HW_BREAKPOINT 363 depends on HAVE_HW_BREAKPOINT
394 help 364 help
395 Depending on the arch implementation 365 Depending on the arch implementation of hardware breakpoints,
396 some of them have separate registers 366 some of them have separate registers for data and instruction
397 breakpoints addresses, others have m 367 breakpoints addresses, others have mixed registers to store
398 them but define the access type in a 368 them but define the access type in a control register.
399 Select this option if your arch impl 369 Select this option if your arch implements breakpoints under the
400 latter fashion. 370 latter fashion.
401 371
402 config HAVE_USER_RETURN_NOTIFIER 372 config HAVE_USER_RETURN_NOTIFIER
403 bool 373 bool
404 374
405 config HAVE_PERF_EVENTS_NMI 375 config HAVE_PERF_EVENTS_NMI
406 bool 376 bool
407 help 377 help
408 System hardware can generate an NMI 378 System hardware can generate an NMI using the perf event
409 subsystem. Also has support for cal 379 subsystem. Also has support for calculating CPU cycle events
410 to determine how many clock cycles i 380 to determine how many clock cycles in a given period.
411 381
412 config HAVE_HARDLOCKUP_DETECTOR_PERF 382 config HAVE_HARDLOCKUP_DETECTOR_PERF
413 bool 383 bool
414 depends on HAVE_PERF_EVENTS_NMI 384 depends on HAVE_PERF_EVENTS_NMI
415 help 385 help
416 The arch chooses to use the generic 386 The arch chooses to use the generic perf-NMI-based hardlockup
417 detector. Must define HAVE_PERF_EVEN 387 detector. Must define HAVE_PERF_EVENTS_NMI.
418 388
419 config HAVE_HARDLOCKUP_DETECTOR_ARCH !! 389 config HAVE_NMI_WATCHDOG
>> 390 depends on HAVE_NMI
420 bool 391 bool
421 help 392 help
422 The arch provides its own hardlockup !! 393 The arch provides a low level NMI watchdog. It provides
423 of the generic ones. !! 394 asm/nmi.h, and defines its own arch_touch_nmi_watchdog().
424 395
425 It uses the same command line parame !! 396 config HAVE_HARDLOCKUP_DETECTOR_ARCH
426 as the generic hardlockup detectors. !! 397 bool
>> 398 select HAVE_NMI_WATCHDOG
>> 399 help
>> 400 The arch chooses to provide its own hardlockup detector, which is
>> 401 a superset of the HAVE_NMI_WATCHDOG. It also conforms to config
>> 402 interfaces and parameters provided by hardlockup detector subsystem.
427 403
428 config HAVE_PERF_REGS 404 config HAVE_PERF_REGS
429 bool 405 bool
430 help 406 help
431 Support selective register dumps for 407 Support selective register dumps for perf events. This includes
432 bit-mapping of each registers and a 408 bit-mapping of each registers and a unique architecture id.
433 409
434 config HAVE_PERF_USER_STACK_DUMP 410 config HAVE_PERF_USER_STACK_DUMP
435 bool 411 bool
436 help 412 help
437 Support user stack dumps for perf ev 413 Support user stack dumps for perf event samples. This needs
438 access to the user stack pointer whi 414 access to the user stack pointer which is not unified across
439 architectures. 415 architectures.
440 416
441 config HAVE_ARCH_JUMP_LABEL 417 config HAVE_ARCH_JUMP_LABEL
442 bool 418 bool
443 419
444 config HAVE_ARCH_JUMP_LABEL_RELATIVE 420 config HAVE_ARCH_JUMP_LABEL_RELATIVE
445 bool 421 bool
446 422
447 config MMU_GATHER_TABLE_FREE 423 config MMU_GATHER_TABLE_FREE
448 bool 424 bool
449 425
450 config MMU_GATHER_RCU_TABLE_FREE 426 config MMU_GATHER_RCU_TABLE_FREE
451 bool 427 bool
452 select MMU_GATHER_TABLE_FREE 428 select MMU_GATHER_TABLE_FREE
453 429
454 config MMU_GATHER_PAGE_SIZE 430 config MMU_GATHER_PAGE_SIZE
455 bool 431 bool
456 432
457 config MMU_GATHER_NO_RANGE 433 config MMU_GATHER_NO_RANGE
458 bool 434 bool
459 select MMU_GATHER_MERGE_VMAS <<
460 <<
461 config MMU_GATHER_NO_FLUSH_CACHE <<
462 bool <<
463 <<
464 config MMU_GATHER_MERGE_VMAS <<
465 bool <<
466 435
467 config MMU_GATHER_NO_GATHER 436 config MMU_GATHER_NO_GATHER
468 bool 437 bool
469 depends on MMU_GATHER_TABLE_FREE 438 depends on MMU_GATHER_TABLE_FREE
470 439
471 config ARCH_WANT_IRQS_OFF_ACTIVATE_MM 440 config ARCH_WANT_IRQS_OFF_ACTIVATE_MM
472 bool 441 bool
473 help 442 help
474 Temporary select until all architect 443 Temporary select until all architectures can be converted to have
475 irqs disabled over activate_mm. Arch 444 irqs disabled over activate_mm. Architectures that do IPI based TLB
476 shootdowns should enable this. 445 shootdowns should enable this.
477 446
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 447 config ARCH_HAVE_NMI_SAFE_CMPXCHG
511 bool 448 bool
512 449
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 450 config HAVE_ALIGNED_STRUCT_PAGE
526 bool 451 bool
527 help 452 help
528 This makes sure that struct pages ar 453 This makes sure that struct pages are double word aligned and that
529 e.g. the SLUB allocator can perform 454 e.g. the SLUB allocator can perform double word atomic operations
530 on a struct page for better performa 455 on a struct page for better performance. However selecting this
531 might increase the size of a struct 456 might increase the size of a struct page by a word.
532 457
533 config HAVE_CMPXCHG_LOCAL 458 config HAVE_CMPXCHG_LOCAL
534 bool 459 bool
535 460
536 config HAVE_CMPXCHG_DOUBLE 461 config HAVE_CMPXCHG_DOUBLE
537 bool 462 bool
538 463
539 config ARCH_WEAK_RELEASE_ACQUIRE 464 config ARCH_WEAK_RELEASE_ACQUIRE
540 bool 465 bool
541 466
542 config ARCH_WANT_IPC_PARSE_VERSION 467 config ARCH_WANT_IPC_PARSE_VERSION
543 bool 468 bool
544 469
545 config ARCH_WANT_COMPAT_IPC_PARSE_VERSION 470 config ARCH_WANT_COMPAT_IPC_PARSE_VERSION
546 bool 471 bool
547 472
548 config ARCH_WANT_OLD_COMPAT_IPC 473 config ARCH_WANT_OLD_COMPAT_IPC
549 select ARCH_WANT_COMPAT_IPC_PARSE_VERS 474 select ARCH_WANT_COMPAT_IPC_PARSE_VERSION
550 bool 475 bool
551 476
552 config HAVE_ARCH_SECCOMP 477 config HAVE_ARCH_SECCOMP
553 bool 478 bool
554 help 479 help
555 An arch should select this symbol to 480 An arch should select this symbol to support seccomp mode 1 (the fixed
556 syscall policy), and must provide an 481 syscall policy), and must provide an overrides for __NR_seccomp_sigreturn,
557 and compat syscalls if the asm-gener 482 and compat syscalls if the asm-generic/seccomp.h defaults need adjustment:
558 - __NR_seccomp_read_32 483 - __NR_seccomp_read_32
559 - __NR_seccomp_write_32 484 - __NR_seccomp_write_32
560 - __NR_seccomp_exit_32 485 - __NR_seccomp_exit_32
561 - __NR_seccomp_sigreturn_32 486 - __NR_seccomp_sigreturn_32
562 487
563 config HAVE_ARCH_SECCOMP_FILTER 488 config HAVE_ARCH_SECCOMP_FILTER
564 bool 489 bool
565 select HAVE_ARCH_SECCOMP 490 select HAVE_ARCH_SECCOMP
566 help 491 help
567 An arch should select this symbol if 492 An arch should select this symbol if it provides all of these things:
568 - all the requirements for HAVE_ARCH 493 - all the requirements for HAVE_ARCH_SECCOMP
569 - syscall_get_arch() 494 - syscall_get_arch()
570 - syscall_get_arguments() 495 - syscall_get_arguments()
571 - syscall_rollback() 496 - syscall_rollback()
572 - syscall_set_return_value() 497 - syscall_set_return_value()
573 - SIGSYS siginfo_t support 498 - SIGSYS siginfo_t support
574 - secure_computing is called from a 499 - secure_computing is called from a ptrace_event()-safe context
575 - secure_computing return value is c 500 - secure_computing return value is checked and a return value of -1
576 results in the system call being s 501 results in the system call being skipped immediately.
577 - seccomp syscall wired up 502 - seccomp syscall wired up
578 - if !HAVE_SPARSE_SYSCALL_NR, have S 503 - if !HAVE_SPARSE_SYSCALL_NR, have SECCOMP_ARCH_NATIVE,
579 SECCOMP_ARCH_NATIVE_NR, SECCOMP_AR 504 SECCOMP_ARCH_NATIVE_NR, SECCOMP_ARCH_NATIVE_NAME defined. If
580 COMPAT is supported, have the SECC 505 COMPAT is supported, have the SECCOMP_ARCH_COMPAT* defines too.
581 506
582 config SECCOMP 507 config SECCOMP
583 prompt "Enable seccomp to safely execu 508 prompt "Enable seccomp to safely execute untrusted bytecode"
584 def_bool y 509 def_bool y
585 depends on HAVE_ARCH_SECCOMP 510 depends on HAVE_ARCH_SECCOMP
586 help 511 help
587 This kernel feature is useful for nu 512 This kernel feature is useful for number crunching applications
588 that may need to handle untrusted by 513 that may need to handle untrusted bytecode during their
589 execution. By using pipes or other t 514 execution. By using pipes or other transports made available
590 to the process as file descriptors s 515 to the process as file descriptors supporting the read/write
591 syscalls, it's possible to isolate t 516 syscalls, it's possible to isolate those applications in their
592 own address space using seccomp. Onc 517 own address space using seccomp. Once seccomp is enabled via
593 prctl(PR_SET_SECCOMP) or the seccomp 518 prctl(PR_SET_SECCOMP) or the seccomp() syscall, it cannot be
594 disabled and the task is only allowe 519 disabled and the task is only allowed to execute a few safe
595 syscalls defined by each seccomp mod 520 syscalls defined by each seccomp mode.
596 521
597 If unsure, say Y. 522 If unsure, say Y.
598 523
599 config SECCOMP_FILTER 524 config SECCOMP_FILTER
600 def_bool y 525 def_bool y
601 depends on HAVE_ARCH_SECCOMP_FILTER && 526 depends on HAVE_ARCH_SECCOMP_FILTER && SECCOMP && NET
602 help 527 help
603 Enable tasks to build secure computi 528 Enable tasks to build secure computing environments defined
604 in terms of Berkeley Packet Filter p 529 in terms of Berkeley Packet Filter programs which implement
605 task-defined system call filtering p 530 task-defined system call filtering polices.
606 531
607 See Documentation/userspace-api/secc 532 See Documentation/userspace-api/seccomp_filter.rst for details.
608 533
609 config SECCOMP_CACHE_DEBUG 534 config SECCOMP_CACHE_DEBUG
610 bool "Show seccomp filter cache status 535 bool "Show seccomp filter cache status in /proc/pid/seccomp_cache"
611 depends on SECCOMP_FILTER && !HAVE_SPA 536 depends on SECCOMP_FILTER && !HAVE_SPARSE_SYSCALL_NR
612 depends on PROC_FS 537 depends on PROC_FS
613 help 538 help
614 This enables the /proc/pid/seccomp_c 539 This enables the /proc/pid/seccomp_cache interface to monitor
615 seccomp cache data. The file format 540 seccomp cache data. The file format is subject to change. Reading
616 the file requires CAP_SYS_ADMIN. 541 the file requires CAP_SYS_ADMIN.
617 542
618 This option is for debugging only. E 543 This option is for debugging only. Enabling presents the risk that
619 an adversary may be able to infer th 544 an adversary may be able to infer the seccomp filter logic.
620 545
621 If unsure, say N. 546 If unsure, say N.
622 547
623 config HAVE_ARCH_STACKLEAK 548 config HAVE_ARCH_STACKLEAK
624 bool 549 bool
625 help 550 help
626 An architecture should select this i 551 An architecture should select this if it has the code which
627 fills the used part of the kernel st 552 fills the used part of the kernel stack with the STACKLEAK_POISON
628 value before returning from system c 553 value before returning from system calls.
629 554
630 config HAVE_STACKPROTECTOR 555 config HAVE_STACKPROTECTOR
631 bool 556 bool
632 help 557 help
633 An arch should select this symbol if 558 An arch should select this symbol if:
634 - it has implemented a stack canary 559 - it has implemented a stack canary (e.g. __stack_chk_guard)
635 560
636 config STACKPROTECTOR 561 config STACKPROTECTOR
637 bool "Stack Protector buffer overflow 562 bool "Stack Protector buffer overflow detection"
638 depends on HAVE_STACKPROTECTOR 563 depends on HAVE_STACKPROTECTOR
639 depends on $(cc-option,-fstack-protect 564 depends on $(cc-option,-fstack-protector)
640 default y 565 default y
641 help 566 help
642 This option turns on the "stack-prot 567 This option turns on the "stack-protector" GCC feature. This
643 feature puts, at the beginning of fu 568 feature puts, at the beginning of functions, a canary value on
644 the stack just before the return add 569 the stack just before the return address, and validates
645 the value just before actually retur 570 the value just before actually returning. Stack based buffer
646 overflows (that need to overwrite th 571 overflows (that need to overwrite this return address) now also
647 overwrite the canary, which gets det 572 overwrite the canary, which gets detected and the attack is then
648 neutralized via a kernel panic. 573 neutralized via a kernel panic.
649 574
650 Functions will have the stack-protec 575 Functions will have the stack-protector canary logic added if they
651 have an 8-byte or larger character a 576 have an 8-byte or larger character array on the stack.
652 577
653 This feature requires gcc version 4. 578 This feature requires gcc version 4.2 or above, or a distribution
654 gcc with the feature backported ("-f 579 gcc with the feature backported ("-fstack-protector").
655 580
656 On an x86 "defconfig" build, this fe 581 On an x86 "defconfig" build, this feature adds canary checks to
657 about 3% of all kernel functions, wh 582 about 3% of all kernel functions, which increases kernel code size
658 by about 0.3%. 583 by about 0.3%.
659 584
660 config STACKPROTECTOR_STRONG 585 config STACKPROTECTOR_STRONG
661 bool "Strong Stack Protector" 586 bool "Strong Stack Protector"
662 depends on STACKPROTECTOR 587 depends on STACKPROTECTOR
663 depends on $(cc-option,-fstack-protect 588 depends on $(cc-option,-fstack-protector-strong)
664 default y 589 default y
665 help 590 help
666 Functions will have the stack-protec 591 Functions will have the stack-protector canary logic added in any
667 of the following conditions: 592 of the following conditions:
668 593
669 - local variable's address used as p 594 - local variable's address used as part of the right hand side of an
670 assignment or function argument 595 assignment or function argument
671 - local variable is an array (or uni 596 - local variable is an array (or union containing an array),
672 regardless of array type or length 597 regardless of array type or length
673 - uses register local variables 598 - uses register local variables
674 599
675 This feature requires gcc version 4. 600 This feature requires gcc version 4.9 or above, or a distribution
676 gcc with the feature backported ("-f 601 gcc with the feature backported ("-fstack-protector-strong").
677 602
678 On an x86 "defconfig" build, this fe 603 On an x86 "defconfig" build, this feature adds canary checks to
679 about 20% of all kernel functions, w 604 about 20% of all kernel functions, which increases the kernel code
680 size by about 2%. 605 size by about 2%.
681 606
682 config ARCH_SUPPORTS_SHADOW_CALL_STACK 607 config ARCH_SUPPORTS_SHADOW_CALL_STACK
683 bool 608 bool
684 help 609 help
685 An architecture should select this i 610 An architecture should select this if it supports the compiler's
686 Shadow Call Stack and implements run 611 Shadow Call Stack and implements runtime support for shadow stack
687 switching. 612 switching.
688 613
689 config SHADOW_CALL_STACK 614 config SHADOW_CALL_STACK
690 bool "Shadow Call Stack" 615 bool "Shadow Call Stack"
691 depends on ARCH_SUPPORTS_SHADOW_CALL_S 616 depends on ARCH_SUPPORTS_SHADOW_CALL_STACK
692 depends on DYNAMIC_FTRACE_WITH_ARGS || !! 617 depends on DYNAMIC_FTRACE_WITH_REGS || !FUNCTION_GRAPH_TRACER
693 depends on MMU <<
694 help 618 help
695 This option enables the compiler's S 619 This option enables the compiler's Shadow Call Stack, which
696 uses a shadow stack to protect funct 620 uses a shadow stack to protect function return addresses from
697 being overwritten by an attacker. Mo 621 being overwritten by an attacker. More information can be found
698 in the compiler's documentation: 622 in the compiler's documentation:
699 623
700 - Clang: https://clang.llvm.org/docs 624 - Clang: https://clang.llvm.org/docs/ShadowCallStack.html
701 - GCC: https://gcc.gnu.org/onlinedoc 625 - GCC: https://gcc.gnu.org/onlinedocs/gcc/Instrumentation-Options.html#Instrumentation-Options
702 626
703 Note that security guarantees in the 627 Note that security guarantees in the kernel differ from the
704 ones documented for user space. The 628 ones documented for user space. The kernel must store addresses
705 of shadow stacks in memory, which me 629 of shadow stacks in memory, which means an attacker capable of
706 reading and writing arbitrary memory 630 reading and writing arbitrary memory may be able to locate them
707 and hijack control flow by modifying 631 and hijack control flow by modifying the stacks.
708 632
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 633 config LTO
717 bool 634 bool
718 help 635 help
719 Selected if the kernel will be built 636 Selected if the kernel will be built using the compiler's LTO feature.
720 637
721 config LTO_CLANG 638 config LTO_CLANG
722 bool 639 bool
723 select LTO 640 select LTO
724 help 641 help
725 Selected if the kernel will be built 642 Selected if the kernel will be built using Clang's LTO feature.
726 643
727 config ARCH_SUPPORTS_LTO_CLANG 644 config ARCH_SUPPORTS_LTO_CLANG
728 bool 645 bool
729 help 646 help
730 An architecture should select this o 647 An architecture should select this option if it supports:
731 - compiling with Clang, 648 - compiling with Clang,
732 - compiling inline assembly with Cla 649 - compiling inline assembly with Clang's integrated assembler,
733 - and linking with LLD. 650 - and linking with LLD.
734 651
735 config ARCH_SUPPORTS_LTO_CLANG_THIN 652 config ARCH_SUPPORTS_LTO_CLANG_THIN
736 bool 653 bool
737 help 654 help
738 An architecture should select this o 655 An architecture should select this option if it can support Clang's
739 ThinLTO mode. 656 ThinLTO mode.
740 657
741 config HAS_LTO_CLANG 658 config HAS_LTO_CLANG
742 def_bool y 659 def_bool y
743 depends on CC_IS_CLANG && LD_IS_LLD && 660 depends on CC_IS_CLANG && LD_IS_LLD && AS_IS_LLVM
744 depends on $(success,$(NM) --help | he 661 depends on $(success,$(NM) --help | head -n 1 | grep -qi llvm)
745 depends on $(success,$(AR) --help | he 662 depends on $(success,$(AR) --help | head -n 1 | grep -qi llvm)
746 depends on ARCH_SUPPORTS_LTO_CLANG 663 depends on ARCH_SUPPORTS_LTO_CLANG
747 depends on !FTRACE_MCOUNT_USE_RECORDMC 664 depends on !FTRACE_MCOUNT_USE_RECORDMCOUNT
748 # https://github.com/ClangBuiltLinux/l !! 665 depends on !KASAN || KASAN_HW_TAGS
749 depends on (!KASAN || KASAN_HW_TAGS || <<
750 depends on (!KCOV || CLANG_VERSION >= <<
751 depends on !GCOV_KERNEL 666 depends on !GCOV_KERNEL
752 help 667 help
753 The compiler and Kconfig options sup 668 The compiler and Kconfig options support building with Clang's
754 LTO. 669 LTO.
755 670
756 choice 671 choice
757 prompt "Link Time Optimization (LTO)" 672 prompt "Link Time Optimization (LTO)"
758 default LTO_NONE 673 default LTO_NONE
759 help 674 help
760 This option enables Link Time Optimi 675 This option enables Link Time Optimization (LTO), which allows the
761 compiler to optimize binaries global 676 compiler to optimize binaries globally.
762 677
763 If unsure, select LTO_NONE. Note tha 678 If unsure, select LTO_NONE. Note that LTO is very resource-intensive
764 so it's disabled by default. 679 so it's disabled by default.
765 680
766 config LTO_NONE 681 config LTO_NONE
767 bool "None" 682 bool "None"
768 help 683 help
769 Build the kernel normally, without L 684 Build the kernel normally, without Link Time Optimization (LTO).
770 685
771 config LTO_CLANG_FULL 686 config LTO_CLANG_FULL
772 bool "Clang Full LTO (EXPERIMENTAL)" 687 bool "Clang Full LTO (EXPERIMENTAL)"
773 depends on HAS_LTO_CLANG 688 depends on HAS_LTO_CLANG
774 depends on !COMPILE_TEST 689 depends on !COMPILE_TEST
775 select LTO_CLANG 690 select LTO_CLANG
776 help 691 help
777 This option enables Clang's full Lin !! 692 This option enables Clang's full Link Time Optimization (LTO), which
778 allows the compiler to optimize the !! 693 allows the compiler to optimize the kernel globally. If you enable
779 this option, the compiler generates !! 694 this option, the compiler generates LLVM bitcode instead of ELF
780 object files, and the actual compila !! 695 object files, and the actual compilation from bitcode happens at
781 the LTO link step, which may take se !! 696 the LTO link step, which may take several minutes depending on the
782 kernel configuration. More informati !! 697 kernel configuration. More information can be found from LLVM's
783 documentation: !! 698 documentation:
784 699
785 https://llvm.org/docs/LinkTimeOpti 700 https://llvm.org/docs/LinkTimeOptimization.html
786 701
787 During link time, this option can us 702 During link time, this option can use a large amount of RAM, and
788 may take much longer than the ThinLT 703 may take much longer than the ThinLTO option.
789 704
790 config LTO_CLANG_THIN 705 config LTO_CLANG_THIN
791 bool "Clang ThinLTO (EXPERIMENTAL)" 706 bool "Clang ThinLTO (EXPERIMENTAL)"
792 depends on HAS_LTO_CLANG && ARCH_SUPPO 707 depends on HAS_LTO_CLANG && ARCH_SUPPORTS_LTO_CLANG_THIN
793 select LTO_CLANG 708 select LTO_CLANG
794 help 709 help
795 This option enables Clang's ThinLTO, 710 This option enables Clang's ThinLTO, which allows for parallel
796 optimization and faster incremental 711 optimization and faster incremental compiles compared to the
797 CONFIG_LTO_CLANG_FULL option. More i 712 CONFIG_LTO_CLANG_FULL option. More information can be found
798 from Clang's documentation: 713 from Clang's documentation:
799 714
800 https://clang.llvm.org/docs/ThinLT 715 https://clang.llvm.org/docs/ThinLTO.html
801 716
802 If unsure, say Y. 717 If unsure, say Y.
803 endchoice 718 endchoice
804 719
805 config ARCH_SUPPORTS_CFI_CLANG 720 config ARCH_SUPPORTS_CFI_CLANG
806 bool 721 bool
807 help 722 help
808 An architecture should select this o 723 An architecture should select this option if it can support Clang's
809 Control-Flow Integrity (CFI) checkin 724 Control-Flow Integrity (CFI) checking.
810 725
811 config ARCH_USES_CFI_TRAPS <<
812 bool <<
813 <<
814 config CFI_CLANG 726 config CFI_CLANG
815 bool "Use Clang's Control Flow Integri 727 bool "Use Clang's Control Flow Integrity (CFI)"
816 depends on ARCH_SUPPORTS_CFI_CLANG !! 728 depends on LTO_CLANG && ARCH_SUPPORTS_CFI_CLANG
817 depends on $(cc-option,-fsanitize=kcfi !! 729 # Clang >= 12:
>> 730 # - https://bugs.llvm.org/show_bug.cgi?id=46258
>> 731 # - https://bugs.llvm.org/show_bug.cgi?id=47479
>> 732 depends on CLANG_VERSION >= 120000
>> 733 select KALLSYMS
818 help 734 help
819 This option enables Clang's forward- !! 735 This option enables Clang’s forward-edge Control Flow Integrity
820 (CFI) checking, where the compiler i 736 (CFI) checking, where the compiler injects a runtime check to each
821 indirect function call to ensure the 737 indirect function call to ensure the target is a valid function with
822 the correct static type. This restri 738 the correct static type. This restricts possible call targets and
823 makes it more difficult for an attac 739 makes it more difficult for an attacker to exploit bugs that allow
824 the modification of stored function 740 the modification of stored function pointers. More information can be
825 found from Clang's documentation: 741 found from Clang's documentation:
826 742
827 https://clang.llvm.org/docs/Contro 743 https://clang.llvm.org/docs/ControlFlowIntegrity.html
828 744
>> 745 config CFI_CLANG_SHADOW
>> 746 bool "Use CFI shadow to speed up cross-module checks"
>> 747 default y
>> 748 depends on CFI_CLANG && MODULES
>> 749 help
>> 750 If you select this option, the kernel builds a fast look-up table of
>> 751 CFI check functions in loaded modules to reduce performance overhead.
>> 752
>> 753 If unsure, say Y.
>> 754
829 config CFI_PERMISSIVE 755 config CFI_PERMISSIVE
830 bool "Use CFI in permissive mode" 756 bool "Use CFI in permissive mode"
831 depends on CFI_CLANG 757 depends on CFI_CLANG
832 help 758 help
833 When selected, Control Flow Integrit 759 When selected, Control Flow Integrity (CFI) violations result in a
834 warning instead of a kernel panic. T 760 warning instead of a kernel panic. This option should only be used
835 for finding indirect call type misma 761 for finding indirect call type mismatches during development.
836 762
837 If unsure, say N. 763 If unsure, say N.
838 764
839 config HAVE_ARCH_WITHIN_STACK_FRAMES 765 config HAVE_ARCH_WITHIN_STACK_FRAMES
840 bool 766 bool
841 help 767 help
842 An architecture should select this i 768 An architecture should select this if it can walk the kernel stack
843 frames to determine if an object is 769 frames to determine if an object is part of either the arguments
844 or local variables (i.e. that it exc 770 or local variables (i.e. that it excludes saved return addresses,
845 and similar) by implementing an inli 771 and similar) by implementing an inline arch_within_stack_frames(),
846 which is used by CONFIG_HARDENED_USE 772 which is used by CONFIG_HARDENED_USERCOPY.
847 773
848 config HAVE_CONTEXT_TRACKING_USER !! 774 config HAVE_CONTEXT_TRACKING
849 bool 775 bool
850 help 776 help
851 Provide kernel/user boundaries probe 777 Provide kernel/user boundaries probes necessary for subsystems
852 that need it, such as userspace RCU 778 that need it, such as userspace RCU extended quiescent state.
853 Syscalls need to be wrapped inside u 779 Syscalls need to be wrapped inside user_exit()-user_enter(), either
854 optimized behind static key or throu 780 optimized behind static key or through the slow path using TIF_NOHZ
855 flag. Exceptions handlers must be wr 781 flag. Exceptions handlers must be wrapped as well. Irqs are already
856 protected inside ct_irq_enter/ct_irq !! 782 protected inside rcu_irq_enter/rcu_irq_exit() but preemption or signal
857 handling on irq exit still need to b 783 handling on irq exit still need to be protected.
858 784
859 config HAVE_CONTEXT_TRACKING_USER_OFFSTACK !! 785 config HAVE_CONTEXT_TRACKING_OFFSTACK
860 bool 786 bool
861 help 787 help
862 Architecture neither relies on excep 788 Architecture neither relies on exception_enter()/exception_exit()
863 nor on schedule_user(). Also preempt 789 nor on schedule_user(). Also preempt_schedule_notrace() and
864 preempt_schedule_irq() can't be call 790 preempt_schedule_irq() can't be called in a preemptible section
865 while context tracking is CONTEXT_US 791 while context tracking is CONTEXT_USER. This feature reflects a sane
866 entry implementation where the follo 792 entry implementation where the following requirements are met on
867 critical entry code, ie: before user 793 critical entry code, ie: before user_exit() or after user_enter():
868 794
869 - Critical entry code isn't preempti 795 - Critical entry code isn't preemptible (or better yet:
870 not interruptible). 796 not interruptible).
871 - No use of RCU read side critical s !! 797 - No use of RCU read side critical sections, unless rcu_nmi_enter()
872 got called. 798 got called.
873 - No use of instrumentation, unless 799 - No use of instrumentation, unless instrumentation_begin() got
874 called. 800 called.
875 801
876 config HAVE_TIF_NOHZ 802 config HAVE_TIF_NOHZ
877 bool 803 bool
878 help 804 help
879 Arch relies on TIF_NOHZ and syscall 805 Arch relies on TIF_NOHZ and syscall slow path to implement context
880 tracking calls to user_enter()/user_ 806 tracking calls to user_enter()/user_exit().
881 807
882 config HAVE_VIRT_CPU_ACCOUNTING 808 config HAVE_VIRT_CPU_ACCOUNTING
883 bool 809 bool
884 810
885 config HAVE_VIRT_CPU_ACCOUNTING_IDLE 811 config HAVE_VIRT_CPU_ACCOUNTING_IDLE
886 bool 812 bool
887 help 813 help
888 Architecture has its own way to acco 814 Architecture has its own way to account idle CPU time and therefore
889 doesn't implement vtime_account_idle 815 doesn't implement vtime_account_idle().
890 816
891 config ARCH_HAS_SCALED_CPUTIME 817 config ARCH_HAS_SCALED_CPUTIME
892 bool 818 bool
893 819
894 config HAVE_VIRT_CPU_ACCOUNTING_GEN 820 config HAVE_VIRT_CPU_ACCOUNTING_GEN
895 bool 821 bool
896 default y if 64BIT 822 default y if 64BIT
897 help 823 help
898 With VIRT_CPU_ACCOUNTING_GEN, cputim 824 With VIRT_CPU_ACCOUNTING_GEN, cputime_t becomes 64-bit.
899 Before enabling this option, arch co 825 Before enabling this option, arch code must be audited
900 to ensure there are no races in conc 826 to ensure there are no races in concurrent read/write of
901 cputime_t. For example, reading/writ 827 cputime_t. For example, reading/writing 64-bit cputime_t on
902 some 32-bit arches may require multi 828 some 32-bit arches may require multiple accesses, so proper
903 locking is needed to protect against 829 locking is needed to protect against concurrent accesses.
904 830
905 config HAVE_IRQ_TIME_ACCOUNTING 831 config HAVE_IRQ_TIME_ACCOUNTING
906 bool 832 bool
907 help 833 help
908 Archs need to ensure they use a high 834 Archs need to ensure they use a high enough resolution clock to
909 support irq time accounting and then 835 support irq time accounting and then call enable_sched_clock_irqtime().
910 836
911 config HAVE_MOVE_PUD 837 config HAVE_MOVE_PUD
912 bool 838 bool
913 help 839 help
914 Architectures that select this are a 840 Architectures that select this are able to move page tables at the
915 PUD level. If there are only 3 page 841 PUD level. If there are only 3 page table levels, the move effectively
916 happens at the PGD level. 842 happens at the PGD level.
917 843
918 config HAVE_MOVE_PMD 844 config HAVE_MOVE_PMD
919 bool 845 bool
920 help 846 help
921 Archs that select this are able to m 847 Archs that select this are able to move page tables at the PMD level.
922 848
923 config HAVE_ARCH_TRANSPARENT_HUGEPAGE 849 config HAVE_ARCH_TRANSPARENT_HUGEPAGE
924 bool 850 bool
925 851
926 config HAVE_ARCH_TRANSPARENT_HUGEPAGE_PUD 852 config HAVE_ARCH_TRANSPARENT_HUGEPAGE_PUD
927 bool 853 bool
928 854
929 config HAVE_ARCH_HUGE_VMAP 855 config HAVE_ARCH_HUGE_VMAP
930 bool 856 bool
931 857
932 # 858 #
933 # Archs that select this would be capable of 859 # Archs that select this would be capable of PMD-sized vmaps (i.e.,
934 # arch_vmap_pmd_supported() returns true). Th 860 # arch_vmap_pmd_supported() returns true). The VM_ALLOW_HUGE_VMAP flag
935 # must be used to enable allocations to use h 861 # must be used to enable allocations to use hugepages.
936 # 862 #
937 config HAVE_ARCH_HUGE_VMALLOC 863 config HAVE_ARCH_HUGE_VMALLOC
938 depends on HAVE_ARCH_HUGE_VMAP 864 depends on HAVE_ARCH_HUGE_VMAP
939 bool 865 bool
940 866
941 config ARCH_WANT_HUGE_PMD_SHARE 867 config ARCH_WANT_HUGE_PMD_SHARE
942 bool 868 bool
943 869
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 870 config HAVE_ARCH_SOFT_DIRTY
953 bool 871 bool
954 872
955 config HAVE_MOD_ARCH_SPECIFIC 873 config HAVE_MOD_ARCH_SPECIFIC
956 bool 874 bool
957 help 875 help
958 The arch uses struct mod_arch_specif 876 The arch uses struct mod_arch_specific to store data. Many arches
959 just need a simple module loader wit 877 just need a simple module loader without arch specific data - those
960 should not enable this. 878 should not enable this.
961 879
962 config MODULES_USE_ELF_RELA 880 config MODULES_USE_ELF_RELA
963 bool 881 bool
964 help 882 help
965 Modules only use ELF RELA relocation 883 Modules only use ELF RELA relocations. Modules with ELF REL
966 relocations will give an error. 884 relocations will give an error.
967 885
968 config MODULES_USE_ELF_REL 886 config MODULES_USE_ELF_REL
969 bool 887 bool
970 help 888 help
971 Modules only use ELF REL relocations 889 Modules only use ELF REL relocations. Modules with ELF RELA
972 relocations will give an error. 890 relocations will give an error.
973 891
974 config ARCH_WANTS_MODULES_DATA_IN_VMALLOC <<
975 bool <<
976 help <<
977 For architectures like powerpc/32 wh <<
978 allocation and need to allocate modu <<
979 <<
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 892 config HAVE_IRQ_EXIT_ON_IRQ_STACK
989 bool 893 bool
990 help 894 help
991 Architecture doesn't only execute th 895 Architecture doesn't only execute the irq handler on the irq stack
992 but also irq_exit(). This way we can 896 but also irq_exit(). This way we can process softirqs on this irq
993 stack instead of switching to a new 897 stack instead of switching to a new one when we call __do_softirq()
994 in the end of an hardirq. 898 in the end of an hardirq.
995 This spares a stack switch and impro 899 This spares a stack switch and improves cache usage on softirq
996 processing. 900 processing.
997 901
998 config HAVE_SOFTIRQ_ON_OWN_STACK 902 config HAVE_SOFTIRQ_ON_OWN_STACK
999 bool 903 bool
1000 help 904 help
1001 Architecture provides a function to 905 Architecture provides a function to run __do_softirq() on a
1002 separate stack. 906 separate stack.
1003 907
1004 config SOFTIRQ_ON_OWN_STACK <<
1005 def_bool HAVE_SOFTIRQ_ON_OWN_STACK && <<
1006 <<
1007 config ALTERNATE_USER_ADDRESS_SPACE 908 config ALTERNATE_USER_ADDRESS_SPACE
1008 bool 909 bool
1009 help 910 help
1010 Architectures set this when the CPU 911 Architectures set this when the CPU uses separate address
1011 spaces for kernel and user space po 912 spaces for kernel and user space pointers. In this case, the
1012 access_ok() check on a __user point 913 access_ok() check on a __user pointer is skipped.
1013 914
1014 config PGTABLE_LEVELS 915 config PGTABLE_LEVELS
1015 int 916 int
1016 default 2 917 default 2
1017 918
1018 config ARCH_HAS_ELF_RANDOMIZE 919 config ARCH_HAS_ELF_RANDOMIZE
1019 bool 920 bool
1020 help 921 help
1021 An architecture supports choosing r 922 An architecture supports choosing randomized locations for
1022 stack, mmap, brk, and ET_DYN. Defin 923 stack, mmap, brk, and ET_DYN. Defined functions:
1023 - arch_mmap_rnd() 924 - arch_mmap_rnd()
1024 - arch_randomize_brk() 925 - arch_randomize_brk()
1025 926
1026 config HAVE_ARCH_MMAP_RND_BITS 927 config HAVE_ARCH_MMAP_RND_BITS
1027 bool 928 bool
1028 help 929 help
1029 An arch should select this symbol i 930 An arch should select this symbol if it supports setting a variable
1030 number of bits for use in establish 931 number of bits for use in establishing the base address for mmap
1031 allocations, has MMU enabled and pr 932 allocations, has MMU enabled and provides values for both:
1032 - ARCH_MMAP_RND_BITS_MIN 933 - ARCH_MMAP_RND_BITS_MIN
1033 - ARCH_MMAP_RND_BITS_MAX 934 - ARCH_MMAP_RND_BITS_MAX
1034 935
1035 config HAVE_EXIT_THREAD 936 config HAVE_EXIT_THREAD
1036 bool 937 bool
1037 help 938 help
1038 An architecture implements exit_thr 939 An architecture implements exit_thread.
1039 940
1040 config ARCH_MMAP_RND_BITS_MIN 941 config ARCH_MMAP_RND_BITS_MIN
1041 int 942 int
1042 943
1043 config ARCH_MMAP_RND_BITS_MAX 944 config ARCH_MMAP_RND_BITS_MAX
1044 int 945 int
1045 946
1046 config ARCH_MMAP_RND_BITS_DEFAULT 947 config ARCH_MMAP_RND_BITS_DEFAULT
1047 int 948 int
1048 949
1049 config ARCH_MMAP_RND_BITS 950 config ARCH_MMAP_RND_BITS
1050 int "Number of bits to use for ASLR o 951 int "Number of bits to use for ASLR of mmap base address" if EXPERT
1051 range ARCH_MMAP_RND_BITS_MIN ARCH_MMA 952 range ARCH_MMAP_RND_BITS_MIN ARCH_MMAP_RND_BITS_MAX
1052 default ARCH_MMAP_RND_BITS_DEFAULT if 953 default ARCH_MMAP_RND_BITS_DEFAULT if ARCH_MMAP_RND_BITS_DEFAULT
1053 default ARCH_MMAP_RND_BITS_MIN 954 default ARCH_MMAP_RND_BITS_MIN
1054 depends on HAVE_ARCH_MMAP_RND_BITS 955 depends on HAVE_ARCH_MMAP_RND_BITS
1055 help 956 help
1056 This value can be used to select th 957 This value can be used to select the number of bits to use to
1057 determine the random offset to the 958 determine the random offset to the base address of vma regions
1058 resulting from mmap allocations. Th 959 resulting from mmap allocations. This value will be bounded
1059 by the architecture's minimum and m 960 by the architecture's minimum and maximum supported values.
1060 961
1061 This value can be changed after boo 962 This value can be changed after boot using the
1062 /proc/sys/vm/mmap_rnd_bits tunable 963 /proc/sys/vm/mmap_rnd_bits tunable
1063 964
1064 config HAVE_ARCH_MMAP_RND_COMPAT_BITS 965 config HAVE_ARCH_MMAP_RND_COMPAT_BITS
1065 bool 966 bool
1066 help 967 help
1067 An arch should select this symbol i 968 An arch should select this symbol if it supports running applications
1068 in compatibility mode, supports set 969 in compatibility mode, supports setting a variable number of bits for
1069 use in establishing the base addres 970 use in establishing the base address for mmap allocations, has MMU
1070 enabled and provides values for bot 971 enabled and provides values for both:
1071 - ARCH_MMAP_RND_COMPAT_BITS_MIN 972 - ARCH_MMAP_RND_COMPAT_BITS_MIN
1072 - ARCH_MMAP_RND_COMPAT_BITS_MAX 973 - ARCH_MMAP_RND_COMPAT_BITS_MAX
1073 974
1074 config ARCH_MMAP_RND_COMPAT_BITS_MIN 975 config ARCH_MMAP_RND_COMPAT_BITS_MIN
1075 int 976 int
1076 977
1077 config ARCH_MMAP_RND_COMPAT_BITS_MAX 978 config ARCH_MMAP_RND_COMPAT_BITS_MAX
1078 int 979 int
1079 980
1080 config ARCH_MMAP_RND_COMPAT_BITS_DEFAULT 981 config ARCH_MMAP_RND_COMPAT_BITS_DEFAULT
1081 int 982 int
1082 983
1083 config ARCH_MMAP_RND_COMPAT_BITS 984 config ARCH_MMAP_RND_COMPAT_BITS
1084 int "Number of bits to use for ASLR o 985 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 986 range ARCH_MMAP_RND_COMPAT_BITS_MIN ARCH_MMAP_RND_COMPAT_BITS_MAX
1086 default ARCH_MMAP_RND_COMPAT_BITS_DEF 987 default ARCH_MMAP_RND_COMPAT_BITS_DEFAULT if ARCH_MMAP_RND_COMPAT_BITS_DEFAULT
1087 default ARCH_MMAP_RND_COMPAT_BITS_MIN 988 default ARCH_MMAP_RND_COMPAT_BITS_MIN
1088 depends on HAVE_ARCH_MMAP_RND_COMPAT_ 989 depends on HAVE_ARCH_MMAP_RND_COMPAT_BITS
1089 help 990 help
1090 This value can be used to select th 991 This value can be used to select the number of bits to use to
1091 determine the random offset to the 992 determine the random offset to the base address of vma regions
1092 resulting from mmap allocations for 993 resulting from mmap allocations for compatible applications This
1093 value will be bounded by the archit 994 value will be bounded by the architecture's minimum and maximum
1094 supported values. 995 supported values.
1095 996
1096 This value can be changed after boo 997 This value can be changed after boot using the
1097 /proc/sys/vm/mmap_rnd_compat_bits t 998 /proc/sys/vm/mmap_rnd_compat_bits tunable
1098 999
1099 config HAVE_ARCH_COMPAT_MMAP_BASES 1000 config HAVE_ARCH_COMPAT_MMAP_BASES
1100 bool 1001 bool
1101 help 1002 help
1102 This allows 64bit applications to i 1003 This allows 64bit applications to invoke 32-bit mmap() syscall
1103 and vice-versa 32-bit applications 1004 and vice-versa 32-bit applications to call 64-bit mmap().
1104 Required for applications doing dif 1005 Required for applications doing different bitness syscalls.
1105 1006
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 1007 config PAGE_SIZE_LESS_THAN_64KB
1190 def_bool y 1008 def_bool y
>> 1009 depends on !ARM64_64K_PAGES
>> 1010 depends on !IA64_PAGE_SIZE_64KB
1191 depends on !PAGE_SIZE_64KB 1011 depends on !PAGE_SIZE_64KB
>> 1012 depends on !PARISC_PAGE_SIZE_64KB
>> 1013 depends on !PPC_64K_PAGES
1192 depends on PAGE_SIZE_LESS_THAN_256KB 1014 depends on PAGE_SIZE_LESS_THAN_256KB
1193 1015
1194 config PAGE_SIZE_LESS_THAN_256KB 1016 config PAGE_SIZE_LESS_THAN_256KB
1195 def_bool y 1017 def_bool y
>> 1018 depends on !PPC_256K_PAGES
1196 depends on !PAGE_SIZE_256KB 1019 depends on !PAGE_SIZE_256KB
1197 1020
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 1021 # This allows to use a set of generic functions to determine mmap base
1208 # address by giving priority to top-down sche 1022 # address by giving priority to top-down scheme only if the process
1209 # is not in legacy mode (compat task, unlimit 1023 # is not in legacy mode (compat task, unlimited stack size or
1210 # sysctl_legacy_va_layout). 1024 # sysctl_legacy_va_layout).
1211 # Architecture that selects this option can p 1025 # Architecture that selects this option can provide its own version of:
1212 # - STACK_RND_MASK 1026 # - STACK_RND_MASK
1213 config ARCH_WANT_DEFAULT_TOPDOWN_MMAP_LAYOUT 1027 config ARCH_WANT_DEFAULT_TOPDOWN_MMAP_LAYOUT
1214 bool 1028 bool
1215 depends on MMU 1029 depends on MMU
1216 select ARCH_HAS_ELF_RANDOMIZE 1030 select ARCH_HAS_ELF_RANDOMIZE
1217 1031
1218 config HAVE_OBJTOOL <<
1219 bool <<
1220 <<
1221 config HAVE_JUMP_LABEL_HACK <<
1222 bool <<
1223 <<
1224 config HAVE_NOINSTR_HACK <<
1225 bool <<
1226 <<
1227 config HAVE_NOINSTR_VALIDATION <<
1228 bool <<
1229 <<
1230 config HAVE_UACCESS_VALIDATION <<
1231 bool <<
1232 select OBJTOOL <<
1233 <<
1234 config HAVE_STACK_VALIDATION 1032 config HAVE_STACK_VALIDATION
1235 bool 1033 bool
1236 help 1034 help
1237 Architecture supports objtool compi !! 1035 Architecture supports the 'objtool check' host tool command, which
1238 validation. !! 1036 performs compile-time stack metadata validation.
1239 1037
1240 config HAVE_RELIABLE_STACKTRACE 1038 config HAVE_RELIABLE_STACKTRACE
1241 bool 1039 bool
1242 help 1040 help
1243 Architecture has either save_stack_ 1041 Architecture has either save_stack_trace_tsk_reliable() or
1244 arch_stack_walk_reliable() function 1042 arch_stack_walk_reliable() function which only returns a stack trace
1245 if it can guarantee the trace is re 1043 if it can guarantee the trace is reliable.
1246 1044
1247 config HAVE_ARCH_HASH 1045 config HAVE_ARCH_HASH
1248 bool 1046 bool
1249 default n 1047 default n
1250 help 1048 help
1251 If this is set, the architecture pr 1049 If this is set, the architecture provides an <asm/hash.h>
1252 file which provides platform-specif 1050 file which provides platform-specific implementations of some
1253 functions in <linux/hash.h> or fs/n 1051 functions in <linux/hash.h> or fs/namei.c.
1254 1052
1255 config HAVE_ARCH_NVRAM_OPS 1053 config HAVE_ARCH_NVRAM_OPS
1256 bool 1054 bool
1257 1055
1258 config ISA_BUS_API 1056 config ISA_BUS_API
1259 def_bool ISA 1057 def_bool ISA
1260 1058
1261 # 1059 #
1262 # ABI hall of shame 1060 # ABI hall of shame
1263 # 1061 #
1264 config CLONE_BACKWARDS 1062 config CLONE_BACKWARDS
1265 bool 1063 bool
1266 help 1064 help
1267 Architecture has tls passed as the 1065 Architecture has tls passed as the 4th argument of clone(2),
1268 not the 5th one. 1066 not the 5th one.
1269 1067
1270 config CLONE_BACKWARDS2 1068 config CLONE_BACKWARDS2
1271 bool 1069 bool
1272 help 1070 help
1273 Architecture has the first two argu 1071 Architecture has the first two arguments of clone(2) swapped.
1274 1072
1275 config CLONE_BACKWARDS3 1073 config CLONE_BACKWARDS3
1276 bool 1074 bool
1277 help 1075 help
1278 Architecture has tls passed as the 1076 Architecture has tls passed as the 3rd argument of clone(2),
1279 not the 5th one. 1077 not the 5th one.
1280 1078
1281 config ODD_RT_SIGACTION 1079 config ODD_RT_SIGACTION
1282 bool 1080 bool
1283 help 1081 help
1284 Architecture has unusual rt_sigacti 1082 Architecture has unusual rt_sigaction(2) arguments
1285 1083
1286 config OLD_SIGSUSPEND 1084 config OLD_SIGSUSPEND
1287 bool 1085 bool
1288 help 1086 help
1289 Architecture has old sigsuspend(2) 1087 Architecture has old sigsuspend(2) syscall, of one-argument variety
1290 1088
1291 config OLD_SIGSUSPEND3 1089 config OLD_SIGSUSPEND3
1292 bool 1090 bool
1293 help 1091 help
1294 Even weirder antique ABI - three-ar 1092 Even weirder antique ABI - three-argument sigsuspend(2)
1295 1093
1296 config OLD_SIGACTION 1094 config OLD_SIGACTION
1297 bool 1095 bool
1298 help 1096 help
1299 Architecture has old sigaction(2) s 1097 Architecture has old sigaction(2) syscall. Nope, not the same
1300 as OLD_SIGSUSPEND | OLD_SIGSUSPEND3 1098 as OLD_SIGSUSPEND | OLD_SIGSUSPEND3 - alpha has sigsuspend(2),
1301 but fairly different variant of sig 1099 but fairly different variant of sigaction(2), thanks to OSF/1
1302 compatibility... 1100 compatibility...
1303 1101
1304 config COMPAT_OLD_SIGACTION 1102 config COMPAT_OLD_SIGACTION
1305 bool 1103 bool
1306 1104
1307 config COMPAT_32BIT_TIME 1105 config COMPAT_32BIT_TIME
1308 bool "Provide system calls for 32-bit 1106 bool "Provide system calls for 32-bit time_t"
1309 default !64BIT || COMPAT 1107 default !64BIT || COMPAT
1310 help 1108 help
1311 This enables 32 bit time_t support 1109 This enables 32 bit time_t support in addition to 64 bit time_t support.
1312 This is relevant on all 32-bit arch 1110 This is relevant on all 32-bit architectures, and 64-bit architectures
1313 as part of compat syscall handling. 1111 as part of compat syscall handling.
1314 1112
1315 config ARCH_NO_PREEMPT 1113 config ARCH_NO_PREEMPT
1316 bool 1114 bool
1317 1115
>> 1116 config ARCH_EPHEMERAL_INODES
>> 1117 def_bool n
>> 1118 help
>> 1119 An arch should select this symbol if it doesn't keep track of inode
>> 1120 instances on its own, but instead relies on something else (e.g. the
>> 1121 host kernel for an UML kernel).
>> 1122
1318 config ARCH_SUPPORTS_RT 1123 config ARCH_SUPPORTS_RT
1319 bool 1124 bool
1320 1125
1321 config CPU_NO_EFFICIENT_FFS 1126 config CPU_NO_EFFICIENT_FFS
1322 def_bool n 1127 def_bool n
1323 1128
1324 config HAVE_ARCH_VMAP_STACK 1129 config HAVE_ARCH_VMAP_STACK
1325 def_bool n 1130 def_bool n
1326 help 1131 help
1327 An arch should select this symbol i 1132 An arch should select this symbol if it can support kernel stacks
1328 in vmalloc space. This means: 1133 in vmalloc space. This means:
1329 1134
1330 - vmalloc space must be large enoug 1135 - vmalloc space must be large enough to hold many kernel stacks.
1331 This may rule out many 32-bit arc 1136 This may rule out many 32-bit architectures.
1332 1137
1333 - Stacks in vmalloc space need to w 1138 - Stacks in vmalloc space need to work reliably. For example, if
1334 vmap page tables are created on d 1139 vmap page tables are created on demand, either this mechanism
1335 needs to work while the stack poi 1140 needs to work while the stack points to a virtual address with
1336 unpopulated page tables or arch c 1141 unpopulated page tables or arch code (switch_to() and switch_mm(),
1337 most likely) needs to ensure that 1142 most likely) needs to ensure that the stack's page table entries
1338 are populated before running on a 1143 are populated before running on a possibly unpopulated stack.
1339 1144
1340 - If the stack overflows into a gua 1145 - If the stack overflows into a guard page, something reasonable
1341 should happen. The definition of 1146 should happen. The definition of "reasonable" is flexible, but
1342 instantly rebooting without loggi 1147 instantly rebooting without logging anything would be unfriendly.
1343 1148
1344 config VMAP_STACK 1149 config VMAP_STACK
1345 default y 1150 default y
1346 bool "Use a virtually-mapped stack" 1151 bool "Use a virtually-mapped stack"
1347 depends on HAVE_ARCH_VMAP_STACK 1152 depends on HAVE_ARCH_VMAP_STACK
1348 depends on !KASAN || KASAN_HW_TAGS || 1153 depends on !KASAN || KASAN_HW_TAGS || KASAN_VMALLOC
1349 help 1154 help
1350 Enable this if you want the use vir 1155 Enable this if you want the use virtually-mapped kernel stacks
1351 with guard pages. This causes kern 1156 with guard pages. This causes kernel stack overflows to be
1352 caught immediately rather than caus 1157 caught immediately rather than causing difficult-to-diagnose
1353 corruption. 1158 corruption.
1354 1159
1355 To use this with software KASAN mod 1160 To use this with software KASAN modes, the architecture must support
1356 backing virtual mappings with real 1161 backing virtual mappings with real shadow memory, and KASAN_VMALLOC
1357 must be enabled. 1162 must be enabled.
1358 1163
1359 config HAVE_ARCH_RANDOMIZE_KSTACK_OFFSET 1164 config HAVE_ARCH_RANDOMIZE_KSTACK_OFFSET
1360 def_bool n 1165 def_bool n
1361 help 1166 help
1362 An arch should select this symbol i 1167 An arch should select this symbol if it can support kernel stack
1363 offset randomization with calls to 1168 offset randomization with calls to add_random_kstack_offset()
1364 during syscall entry and choose_ran 1169 during syscall entry and choose_random_kstack_offset() during
1365 syscall exit. Careful removal of -f 1170 syscall exit. Careful removal of -fstack-protector-strong and
1366 -fstack-protector should also be ap 1171 -fstack-protector should also be applied to the entry code and
1367 closely examined, as the artificial 1172 closely examined, as the artificial stack bump looks like an array
1368 to the compiler, so it will attempt 1173 to the compiler, so it will attempt to add canary checks regardless
1369 of the static branch state. 1174 of the static branch state.
1370 1175
1371 config RANDOMIZE_KSTACK_OFFSET 1176 config RANDOMIZE_KSTACK_OFFSET
1372 bool "Support for randomizing kernel 1177 bool "Support for randomizing kernel stack offset on syscall entry" if EXPERT
1373 default y 1178 default y
1374 depends on HAVE_ARCH_RANDOMIZE_KSTACK 1179 depends on HAVE_ARCH_RANDOMIZE_KSTACK_OFFSET
1375 depends on INIT_STACK_NONE || !CC_IS_ 1180 depends on INIT_STACK_NONE || !CC_IS_CLANG || CLANG_VERSION >= 140000
1376 help 1181 help
1377 The kernel stack offset can be rand 1182 The kernel stack offset can be randomized (after pt_regs) by
1378 roughly 5 bits of entropy, frustrat 1183 roughly 5 bits of entropy, frustrating memory corruption
1379 attacks that depend on stack addres 1184 attacks that depend on stack address determinism or
1380 cross-syscall address exposures. 1185 cross-syscall address exposures.
1381 1186
1382 The feature is controlled via the " 1187 The feature is controlled via the "randomize_kstack_offset=on/off"
1383 kernel boot param, and if turned of 1188 kernel boot param, and if turned off has zero overhead due to its use
1384 of static branches (see JUMP_LABEL) 1189 of static branches (see JUMP_LABEL).
1385 1190
1386 If unsure, say Y. 1191 If unsure, say Y.
1387 1192
1388 config RANDOMIZE_KSTACK_OFFSET_DEFAULT 1193 config RANDOMIZE_KSTACK_OFFSET_DEFAULT
1389 bool "Default state of kernel stack o 1194 bool "Default state of kernel stack offset randomization"
1390 depends on RANDOMIZE_KSTACK_OFFSET 1195 depends on RANDOMIZE_KSTACK_OFFSET
1391 help 1196 help
1392 Kernel stack offset randomization i 1197 Kernel stack offset randomization is controlled by kernel boot param
1393 "randomize_kstack_offset=on/off", a 1198 "randomize_kstack_offset=on/off", and this config chooses the default
1394 boot state. 1199 boot state.
1395 1200
1396 config ARCH_OPTIONAL_KERNEL_RWX 1201 config ARCH_OPTIONAL_KERNEL_RWX
1397 def_bool n 1202 def_bool n
1398 1203
1399 config ARCH_OPTIONAL_KERNEL_RWX_DEFAULT 1204 config ARCH_OPTIONAL_KERNEL_RWX_DEFAULT
1400 def_bool n 1205 def_bool n
1401 1206
1402 config ARCH_HAS_STRICT_KERNEL_RWX 1207 config ARCH_HAS_STRICT_KERNEL_RWX
1403 def_bool n 1208 def_bool n
1404 1209
1405 config STRICT_KERNEL_RWX 1210 config STRICT_KERNEL_RWX
1406 bool "Make kernel text and rodata rea 1211 bool "Make kernel text and rodata read-only" if ARCH_OPTIONAL_KERNEL_RWX
1407 depends on ARCH_HAS_STRICT_KERNEL_RWX 1212 depends on ARCH_HAS_STRICT_KERNEL_RWX
1408 default !ARCH_OPTIONAL_KERNEL_RWX || 1213 default !ARCH_OPTIONAL_KERNEL_RWX || ARCH_OPTIONAL_KERNEL_RWX_DEFAULT
1409 help 1214 help
1410 If this is set, kernel text and rod 1215 If this is set, kernel text and rodata memory will be made read-only,
1411 and non-text memory will be made no 1216 and non-text memory will be made non-executable. This provides
1412 protection against certain security 1217 protection against certain security exploits (e.g. executing the heap
1413 or modifying text) 1218 or modifying text)
1414 1219
1415 These features are considered stand 1220 These features are considered standard security practice these days.
1416 You should say Y here in almost all 1221 You should say Y here in almost all cases.
1417 1222
1418 config ARCH_HAS_STRICT_MODULE_RWX 1223 config ARCH_HAS_STRICT_MODULE_RWX
1419 def_bool n 1224 def_bool n
1420 1225
1421 config STRICT_MODULE_RWX 1226 config STRICT_MODULE_RWX
1422 bool "Set loadable kernel module data 1227 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 1228 depends on ARCH_HAS_STRICT_MODULE_RWX && MODULES
1424 default !ARCH_OPTIONAL_KERNEL_RWX || 1229 default !ARCH_OPTIONAL_KERNEL_RWX || ARCH_OPTIONAL_KERNEL_RWX_DEFAULT
1425 help 1230 help
1426 If this is set, module text and rod 1231 If this is set, module text and rodata memory will be made read-only,
1427 and non-text memory will be made no 1232 and non-text memory will be made non-executable. This provides
1428 protection against certain security 1233 protection against certain security exploits (e.g. writing to text)
1429 1234
1430 # select if the architecture provides an asm/ 1235 # select if the architecture provides an asm/dma-direct.h header
1431 config ARCH_HAS_PHYS_TO_DMA 1236 config ARCH_HAS_PHYS_TO_DMA
1432 bool 1237 bool
1433 1238
1434 config HAVE_ARCH_COMPILER_H 1239 config HAVE_ARCH_COMPILER_H
1435 bool 1240 bool
1436 help 1241 help
1437 An architecture can select this if 1242 An architecture can select this if it provides an
1438 asm/compiler.h header that should b 1243 asm/compiler.h header that should be included after
1439 linux/compiler-*.h in order to over 1244 linux/compiler-*.h in order to override macro definitions that those
1440 headers generally provide. 1245 headers generally provide.
1441 1246
1442 config HAVE_ARCH_PREL32_RELOCATIONS 1247 config HAVE_ARCH_PREL32_RELOCATIONS
1443 bool 1248 bool
1444 help 1249 help
1445 May be selected by an architecture 1250 May be selected by an architecture if it supports place-relative
1446 32-bit relocations, both in the too 1251 32-bit relocations, both in the toolchain and in the module loader,
1447 in which case relative references c 1252 in which case relative references can be used in special sections
1448 for PCI fixup, initcalls etc which 1253 for PCI fixup, initcalls etc which are only half the size on 64 bit
1449 architectures, and don't require ru 1254 architectures, and don't require runtime relocation on relocatable
1450 kernels. 1255 kernels.
1451 1256
1452 config ARCH_USE_MEMREMAP_PROT 1257 config ARCH_USE_MEMREMAP_PROT
1453 bool 1258 bool
1454 1259
1455 config LOCK_EVENT_COUNTS 1260 config LOCK_EVENT_COUNTS
1456 bool "Locking event counts collection 1261 bool "Locking event counts collection"
1457 depends on DEBUG_FS 1262 depends on DEBUG_FS
1458 help 1263 help
1459 Enable light-weight counting of var 1264 Enable light-weight counting of various locking related events
1460 in the system with minimal performa 1265 in the system with minimal performance impact. This reduces
1461 the chance of application behavior 1266 the chance of application behavior change because of timing
1462 differences. The counts are reporte 1267 differences. The counts are reported via debugfs.
1463 1268
1464 # Select if the architecture has support for 1269 # Select if the architecture has support for applying RELR relocations.
1465 config ARCH_HAS_RELR 1270 config ARCH_HAS_RELR
1466 bool 1271 bool
1467 1272
1468 config RELR 1273 config RELR
1469 bool "Use RELR relocation packing" 1274 bool "Use RELR relocation packing"
1470 depends on ARCH_HAS_RELR && TOOLS_SUP 1275 depends on ARCH_HAS_RELR && TOOLS_SUPPORT_RELR
1471 default y 1276 default y
1472 help 1277 help
1473 Store the kernel's dynamic relocati 1278 Store the kernel's dynamic relocations in the RELR relocation packing
1474 format. Requires a compatible linke 1279 format. Requires a compatible linker (LLD supports this feature), as
1475 well as compatible NM and OBJCOPY u 1280 well as compatible NM and OBJCOPY utilities (llvm-nm and llvm-objcopy
1476 are compatible). 1281 are compatible).
1477 1282
1478 config ARCH_HAS_MEM_ENCRYPT 1283 config ARCH_HAS_MEM_ENCRYPT
1479 bool 1284 bool
1480 1285
1481 config ARCH_HAS_CC_PLATFORM 1286 config ARCH_HAS_CC_PLATFORM
1482 bool 1287 bool
1483 1288
1484 config HAVE_SPARSE_SYSCALL_NR 1289 config HAVE_SPARSE_SYSCALL_NR
1485 bool !! 1290 bool
1486 help !! 1291 help
1487 An architecture should select this !! 1292 An architecture should select this if its syscall numbering is sparse
1488 to save space. For example, MIPS ar 1293 to save space. For example, MIPS architecture has a syscall array with
1489 entries at 4000, 5000 and 6000 loca 1294 entries at 4000, 5000 and 6000 locations. This option turns on syscall
1490 related optimizations for a given a 1295 related optimizations for a given architecture.
1491 1296
1492 config ARCH_HAS_VDSO_DATA 1297 config ARCH_HAS_VDSO_DATA
1493 bool 1298 bool
1494 1299
1495 config HAVE_STATIC_CALL 1300 config HAVE_STATIC_CALL
1496 bool 1301 bool
1497 1302
1498 config HAVE_STATIC_CALL_INLINE 1303 config HAVE_STATIC_CALL_INLINE
1499 bool 1304 bool
1500 depends on HAVE_STATIC_CALL 1305 depends on HAVE_STATIC_CALL
1501 select OBJTOOL <<
1502 1306
1503 config HAVE_PREEMPT_DYNAMIC 1307 config HAVE_PREEMPT_DYNAMIC
1504 bool 1308 bool
1505 1309
1506 config HAVE_PREEMPT_DYNAMIC_CALL 1310 config HAVE_PREEMPT_DYNAMIC_CALL
1507 bool 1311 bool
1508 depends on HAVE_STATIC_CALL 1312 depends on HAVE_STATIC_CALL
1509 select HAVE_PREEMPT_DYNAMIC 1313 select HAVE_PREEMPT_DYNAMIC
1510 help 1314 help
1511 An architecture should select this !! 1315 An architecture should select this if it can handle the preemption
1512 model being selected at boot time u !! 1316 model being selected at boot time using static calls.
1513 1317
1514 Where an architecture selects HAVE_ !! 1318 Where an architecture selects HAVE_STATIC_CALL_INLINE, any call to a
1515 preemption function will be patched !! 1319 preemption function will be patched directly.
1516 1320
1517 Where an architecture does not sele !! 1321 Where an architecture does not select HAVE_STATIC_CALL_INLINE, any
1518 call to a preemption function will !! 1322 call to a preemption function will go through a trampoline, and the
1519 trampoline will be patched. !! 1323 trampoline will be patched.
1520 1324
1521 It is strongly advised to support i !! 1325 It is strongly advised to support inline static call to avoid any
1522 overhead. !! 1326 overhead.
1523 1327
1524 config HAVE_PREEMPT_DYNAMIC_KEY 1328 config HAVE_PREEMPT_DYNAMIC_KEY
1525 bool 1329 bool
1526 depends on HAVE_ARCH_JUMP_LABEL !! 1330 depends on HAVE_ARCH_JUMP_LABEL && CC_HAS_ASM_GOTO
1527 select HAVE_PREEMPT_DYNAMIC 1331 select HAVE_PREEMPT_DYNAMIC
1528 help 1332 help
1529 An architecture should select this !! 1333 An architecture should select this if it can handle the preemption
1530 model being selected at boot time u !! 1334 model being selected at boot time using static keys.
1531 1335
1532 Each preemption function will be gi !! 1336 Each preemption function will be given an early return based on a
1533 static key. This should have slight !! 1337 static key. This should have slightly lower overhead than non-inline
1534 static calls, as this effectively i !! 1338 static calls, as this effectively inlines each trampoline into the
1535 start of its callee. This may avoid !! 1339 start of its callee. This may avoid redundant work, and may
1536 integrate better with CFI schemes. !! 1340 integrate better with CFI schemes.
1537 1341
1538 This will have greater overhead tha !! 1342 This will have greater overhead than using inline static calls as
1539 the call to the preemption function !! 1343 the call to the preemption function cannot be entirely elided.
1540 1344
1541 config ARCH_WANT_LD_ORPHAN_WARN 1345 config ARCH_WANT_LD_ORPHAN_WARN
1542 bool 1346 bool
1543 help 1347 help
1544 An arch should select this symbol o 1348 An arch should select this symbol once all linker sections are explicitly
1545 included, size-asserted, or discard 1349 included, size-asserted, or discarded in the linker scripts. This is
1546 important because we never want exp 1350 important because we never want expected sections to be placed heuristically
1547 by the linker, since the locations 1351 by the linker, since the locations of such sections can change between linker
1548 versions. 1352 versions.
1549 1353
1550 config HAVE_ARCH_PFN_VALID 1354 config HAVE_ARCH_PFN_VALID
1551 bool 1355 bool
1552 1356
1553 config ARCH_SUPPORTS_DEBUG_PAGEALLOC 1357 config ARCH_SUPPORTS_DEBUG_PAGEALLOC
1554 bool 1358 bool
1555 1359
1556 config ARCH_SUPPORTS_PAGE_TABLE_CHECK 1360 config ARCH_SUPPORTS_PAGE_TABLE_CHECK
1557 bool 1361 bool
1558 1362
1559 config ARCH_SPLIT_ARG64 1363 config ARCH_SPLIT_ARG64
1560 bool 1364 bool
1561 help 1365 help
1562 If a 32-bit architecture requires 6 !! 1366 If a 32-bit architecture requires 64-bit arguments to be split into
1563 pairs of 32-bit arguments, select t !! 1367 pairs of 32-bit arguments, select this option.
1564 1368
1565 config ARCH_HAS_ELFCORE_COMPAT 1369 config ARCH_HAS_ELFCORE_COMPAT
1566 bool 1370 bool
1567 1371
1568 config ARCH_HAS_PARANOID_L1D_FLUSH 1372 config ARCH_HAS_PARANOID_L1D_FLUSH
1569 bool 1373 bool
1570 1374
1571 config ARCH_HAVE_TRACE_MMIO_ACCESS <<
1572 bool <<
1573 <<
1574 config DYNAMIC_SIGFRAME 1375 config DYNAMIC_SIGFRAME
1575 bool 1376 bool
1576 1377
1577 # Select, if arch has a named attribute group 1378 # Select, if arch has a named attribute group bound to NUMA device nodes.
1578 config HAVE_ARCH_NODE_DEV_GROUP 1379 config HAVE_ARCH_NODE_DEV_GROUP
1579 bool 1380 bool
1580 1381
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" 1382 source "kernel/gcov/Kconfig"
1604 1383
1605 source "scripts/gcc-plugins/Kconfig" 1384 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 1385
1646 endmenu 1386 endmenu
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