1 # SPDX-License-Identifier: GPL-2.0 1 # SPDX-License-Identifier: GPL-2.0
2 # 2 #
3 # General architecture dependent options 3 # General architecture dependent options
4 # 4 #
5 5
6 # 6 #
7 # Note: arch/$(SRCARCH)/Kconfig needs to be in 7 # Note: arch/$(SRCARCH)/Kconfig needs to be included first so that it can
8 # override the default values in this file. 8 # override the default values in this file.
9 # 9 #
10 source "arch/$(SRCARCH)/Kconfig" 10 source "arch/$(SRCARCH)/Kconfig"
11 11
12 config ARCH_CONFIGURES_CPU_MITIGATIONS !! 12 menu "General architecture-dependent options"
>> 13
>> 14 config CRASH_CORE
13 bool 15 bool
14 16
15 if !ARCH_CONFIGURES_CPU_MITIGATIONS !! 17 config KEXEC_CORE
16 config CPU_MITIGATIONS !! 18 select CRASH_CORE
17 def_bool y !! 19 bool
18 endif <<
19 20
20 # !! 21 config KEXEC_ELF
21 # Selected by architectures that need custom D <<
22 # IOMMUs not handled by dma-iommu. Drivers mu <<
23 # <<
24 config ARCH_HAS_DMA_OPS <<
25 depends on HAS_DMA <<
26 select DMA_OPS_HELPERS <<
27 bool 22 bool
28 23
29 menu "General architecture-dependent options" !! 24 config HAVE_IMA_KEXEC
>> 25 bool
30 26
31 config ARCH_HAS_SUBPAGE_FAULTS 27 config ARCH_HAS_SUBPAGE_FAULTS
32 bool 28 bool
33 help 29 help
34 Select if the architecture can check 30 Select if the architecture can check permissions at sub-page
35 granularity (e.g. arm64 MTE). The pr 31 granularity (e.g. arm64 MTE). The probe_user_*() functions
36 must be implemented. 32 must be implemented.
37 33
38 config HOTPLUG_SMT 34 config HOTPLUG_SMT
39 bool 35 bool
40 36
41 config SMT_NUM_THREADS_DYNAMIC <<
42 bool <<
43 <<
44 # Selected by HOTPLUG_CORE_SYNC_DEAD or HOTPLU <<
45 config HOTPLUG_CORE_SYNC <<
46 bool <<
47 <<
48 # Basic CPU dead synchronization selected by a <<
49 config HOTPLUG_CORE_SYNC_DEAD <<
50 bool <<
51 select HOTPLUG_CORE_SYNC <<
52 <<
53 # Full CPU synchronization with alive state se <<
54 config HOTPLUG_CORE_SYNC_FULL <<
55 bool <<
56 select HOTPLUG_CORE_SYNC_DEAD if HOTPL <<
57 select HOTPLUG_CORE_SYNC <<
58 <<
59 config HOTPLUG_SPLIT_STARTUP <<
60 bool <<
61 select HOTPLUG_CORE_SYNC_FULL <<
62 <<
63 config HOTPLUG_PARALLEL <<
64 bool <<
65 select HOTPLUG_SPLIT_STARTUP <<
66 <<
67 config GENERIC_ENTRY 37 config GENERIC_ENTRY
68 bool !! 38 bool
69 39
70 config KPROBES 40 config KPROBES
71 bool "Kprobes" 41 bool "Kprobes"
>> 42 depends on MODULES
72 depends on HAVE_KPROBES 43 depends on HAVE_KPROBES
73 select KALLSYMS 44 select KALLSYMS
74 select EXECMEM !! 45 select TASKS_RCU if PREEMPTION
75 select NEED_TASKS_RCU <<
76 help 46 help
77 Kprobes allows you to trap at almost 47 Kprobes allows you to trap at almost any kernel address and
78 execute a callback function. regist 48 execute a callback function. register_kprobe() establishes
79 a probepoint and specifies the callb 49 a probepoint and specifies the callback. Kprobes is useful
80 for kernel debugging, non-intrusive 50 for kernel debugging, non-intrusive instrumentation and testing.
81 If in doubt, say "N". 51 If in doubt, say "N".
82 52
83 config JUMP_LABEL 53 config JUMP_LABEL
84 bool "Optimize very unlikely/likely br 54 bool "Optimize very unlikely/likely branches"
85 depends on HAVE_ARCH_JUMP_LABEL 55 depends on HAVE_ARCH_JUMP_LABEL
86 select OBJTOOL if HAVE_JUMP_LABEL_HACK 56 select OBJTOOL if HAVE_JUMP_LABEL_HACK
87 help 57 help
88 This option enables a transparent br !! 58 This option enables a transparent branch optimization that
89 makes certain almost-always-true or !! 59 makes certain almost-always-true or almost-always-false branch
90 conditions even cheaper to execute w !! 60 conditions even cheaper to execute within the kernel.
91 !! 61
92 Certain performance-sensitive kernel !! 62 Certain performance-sensitive kernel code, such as trace points,
93 scheduler functionality, networking !! 63 scheduler functionality, networking code and KVM have such
94 branches and include support for thi !! 64 branches and include support for this optimization technique.
95 !! 65
96 If it is detected that the compiler !! 66 If it is detected that the compiler has support for "asm goto",
97 the kernel will compile such branche !! 67 the kernel will compile such branches with just a nop
98 instruction. When the condition flag !! 68 instruction. When the condition flag is toggled to true, the
99 nop will be converted to a jump inst !! 69 nop will be converted to a jump instruction to execute the
100 conditional block of instructions. !! 70 conditional block of instructions.
101 !! 71
102 This technique lowers overhead and s !! 72 This technique lowers overhead and stress on the branch prediction
103 of the processor and generally makes !! 73 of the processor and generally makes the kernel faster. The update
104 of the condition is slower, but thos !! 74 of the condition is slower, but those are always very rare.
105 75
106 ( On 32-bit x86, the necessary optio !! 76 ( On 32-bit x86, the necessary options added to the compiler
107 flags may increase the size of the !! 77 flags may increase the size of the kernel slightly. )
108 78
109 config STATIC_KEYS_SELFTEST 79 config STATIC_KEYS_SELFTEST
110 bool "Static key selftest" 80 bool "Static key selftest"
111 depends on JUMP_LABEL 81 depends on JUMP_LABEL
112 help 82 help
113 Boot time self-test of the branch pa 83 Boot time self-test of the branch patching code.
114 84
115 config STATIC_CALL_SELFTEST 85 config STATIC_CALL_SELFTEST
116 bool "Static call selftest" 86 bool "Static call selftest"
117 depends on HAVE_STATIC_CALL 87 depends on HAVE_STATIC_CALL
118 help 88 help
119 Boot time self-test of the call patc 89 Boot time self-test of the call patching code.
120 90
121 config OPTPROBES 91 config OPTPROBES
122 def_bool y 92 def_bool y
123 depends on KPROBES && HAVE_OPTPROBES 93 depends on KPROBES && HAVE_OPTPROBES
124 select NEED_TASKS_RCU !! 94 select TASKS_RCU if PREEMPTION
125 95
126 config KPROBES_ON_FTRACE 96 config KPROBES_ON_FTRACE
127 def_bool y 97 def_bool y
128 depends on KPROBES && HAVE_KPROBES_ON_ 98 depends on KPROBES && HAVE_KPROBES_ON_FTRACE
129 depends on DYNAMIC_FTRACE_WITH_REGS 99 depends on DYNAMIC_FTRACE_WITH_REGS
130 help 100 help
131 If function tracer is enabled and th !! 101 If function tracer is enabled and the arch supports full
132 passing of pt_regs to function traci !! 102 passing of pt_regs to function tracing, then kprobes can
133 optimize on top of function tracing. !! 103 optimize on top of function tracing.
134 104
135 config UPROBES 105 config UPROBES
136 def_bool n 106 def_bool n
137 depends on ARCH_SUPPORTS_UPROBES 107 depends on ARCH_SUPPORTS_UPROBES
138 help 108 help
139 Uprobes is the user-space counterpar 109 Uprobes is the user-space counterpart to kprobes: they
140 enable instrumentation applications 110 enable instrumentation applications (such as 'perf probe')
141 to establish unintrusive probes in u 111 to establish unintrusive probes in user-space binaries and
142 libraries, by executing handler func 112 libraries, by executing handler functions when the probes
143 are hit by user-space applications. 113 are hit by user-space applications.
144 114
145 ( These probes come in the form of s 115 ( These probes come in the form of single-byte breakpoints,
146 managed by the kernel and kept tra 116 managed by the kernel and kept transparent to the probed
147 application. ) 117 application. )
148 118
149 config HAVE_64BIT_ALIGNED_ACCESS 119 config HAVE_64BIT_ALIGNED_ACCESS
150 def_bool 64BIT && !HAVE_EFFICIENT_UNAL 120 def_bool 64BIT && !HAVE_EFFICIENT_UNALIGNED_ACCESS
151 help 121 help
152 Some architectures require 64 bit ac 122 Some architectures require 64 bit accesses to be 64 bit
153 aligned, which also requires structs 123 aligned, which also requires structs containing 64 bit values
154 to be 64 bit aligned too. This inclu 124 to be 64 bit aligned too. This includes some 32 bit
155 architectures which can do 64 bit ac 125 architectures which can do 64 bit accesses, as well as 64 bit
156 architectures without unaligned acce 126 architectures without unaligned access.
157 127
158 This symbol should be selected by an 128 This symbol should be selected by an architecture if 64 bit
159 accesses are required to be 64 bit a 129 accesses are required to be 64 bit aligned in this way even
160 though it is not a 64 bit architectu 130 though it is not a 64 bit architecture.
161 131
162 See Documentation/core-api/unaligned 132 See Documentation/core-api/unaligned-memory-access.rst for
163 more information on the topic of una 133 more information on the topic of unaligned memory accesses.
164 134
165 config HAVE_EFFICIENT_UNALIGNED_ACCESS 135 config HAVE_EFFICIENT_UNALIGNED_ACCESS
166 bool 136 bool
167 help 137 help
168 Some architectures are unable to per 138 Some architectures are unable to perform unaligned accesses
169 without the use of get_unaligned/put 139 without the use of get_unaligned/put_unaligned. Others are
170 unable to perform such accesses effi 140 unable to perform such accesses efficiently (e.g. trap on
171 unaligned access and require fixing 141 unaligned access and require fixing it up in the exception
172 handler.) 142 handler.)
173 143
174 This symbol should be selected by an 144 This symbol should be selected by an architecture if it can
175 perform unaligned accesses efficient 145 perform unaligned accesses efficiently to allow different
176 code paths to be selected for these 146 code paths to be selected for these cases. Some network
177 drivers, for example, could opt to n 147 drivers, for example, could opt to not fix up alignment
178 problems with received packets if do 148 problems with received packets if doing so would not help
179 much. 149 much.
180 150
181 See Documentation/core-api/unaligned 151 See Documentation/core-api/unaligned-memory-access.rst for more
182 information on the topic of unaligne 152 information on the topic of unaligned memory accesses.
183 153
184 config ARCH_USE_BUILTIN_BSWAP 154 config ARCH_USE_BUILTIN_BSWAP
185 bool 155 bool
186 help 156 help
187 Modern versions of GCC (since 4.4) h !! 157 Modern versions of GCC (since 4.4) have builtin functions
188 for handling byte-swapping. Using th !! 158 for handling byte-swapping. Using these, instead of the old
189 inline assembler that the architectu !! 159 inline assembler that the architecture code provides in the
190 __arch_bswapXX() macros, allows the !! 160 __arch_bswapXX() macros, allows the compiler to see what's
191 happening and offers more opportunit !! 161 happening and offers more opportunity for optimisation. In
192 particular, the compiler will be abl !! 162 particular, the compiler will be able to combine the byteswap
193 with a nearby load or store and use !! 163 with a nearby load or store and use load-and-swap or
194 store-and-swap instructions if the a !! 164 store-and-swap instructions if the architecture has them. It
195 should almost *never* result in code !! 165 should almost *never* result in code which is worse than the
196 hand-coded assembler in <asm/swab.h> !! 166 hand-coded assembler in <asm/swab.h>. But just in case it
197 does, the use of the builtins is opt !! 167 does, the use of the builtins is optional.
198 !! 168
199 Any architecture with load-and-swap !! 169 Any architecture with load-and-swap or store-and-swap
200 instructions should set this. And it !! 170 instructions should set this. And it shouldn't hurt to set it
201 on architectures that don't have suc !! 171 on architectures that don't have such instructions.
202 172
203 config KRETPROBES 173 config KRETPROBES
204 def_bool y 174 def_bool y
205 depends on KPROBES && (HAVE_KRETPROBES 175 depends on KPROBES && (HAVE_KRETPROBES || HAVE_RETHOOK)
206 176
207 config KRETPROBE_ON_RETHOOK 177 config KRETPROBE_ON_RETHOOK
208 def_bool y 178 def_bool y
209 depends on HAVE_RETHOOK 179 depends on HAVE_RETHOOK
210 depends on KRETPROBES 180 depends on KRETPROBES
211 select RETHOOK 181 select RETHOOK
212 182
213 config USER_RETURN_NOTIFIER 183 config USER_RETURN_NOTIFIER
214 bool 184 bool
215 depends on HAVE_USER_RETURN_NOTIFIER 185 depends on HAVE_USER_RETURN_NOTIFIER
216 help 186 help
217 Provide a kernel-internal notificati 187 Provide a kernel-internal notification when a cpu is about to
218 switch to user mode. 188 switch to user mode.
219 189
220 config HAVE_IOREMAP_PROT 190 config HAVE_IOREMAP_PROT
221 bool 191 bool
222 192
223 config HAVE_KPROBES 193 config HAVE_KPROBES
224 bool 194 bool
225 195
226 config HAVE_KRETPROBES 196 config HAVE_KRETPROBES
227 bool 197 bool
228 198
229 config HAVE_OPTPROBES 199 config HAVE_OPTPROBES
230 bool 200 bool
231 201
232 config HAVE_KPROBES_ON_FTRACE 202 config HAVE_KPROBES_ON_FTRACE
233 bool 203 bool
234 204
235 config ARCH_CORRECT_STACKTRACE_ON_KRETPROBE 205 config ARCH_CORRECT_STACKTRACE_ON_KRETPROBE
236 bool 206 bool
237 help 207 help
238 Since kretprobes modifies return add 208 Since kretprobes modifies return address on the stack, the
239 stacktrace may see the kretprobe tra 209 stacktrace may see the kretprobe trampoline address instead
240 of correct one. If the architecture 210 of correct one. If the architecture stacktrace code and
241 unwinder can adjust such entries, se 211 unwinder can adjust such entries, select this configuration.
242 212
243 config HAVE_FUNCTION_ERROR_INJECTION 213 config HAVE_FUNCTION_ERROR_INJECTION
244 bool 214 bool
245 215
246 config HAVE_NMI 216 config HAVE_NMI
247 bool 217 bool
248 218
249 config HAVE_FUNCTION_DESCRIPTORS 219 config HAVE_FUNCTION_DESCRIPTORS
250 bool 220 bool
251 221
252 config TRACE_IRQFLAGS_SUPPORT 222 config TRACE_IRQFLAGS_SUPPORT
253 bool 223 bool
254 224
255 config TRACE_IRQFLAGS_NMI_SUPPORT 225 config TRACE_IRQFLAGS_NMI_SUPPORT
256 bool 226 bool
257 227
258 # 228 #
259 # An arch should select this if it provides al 229 # An arch should select this if it provides all these things:
260 # 230 #
261 # task_pt_regs() in asm/process 231 # task_pt_regs() in asm/processor.h or asm/ptrace.h
262 # arch_has_single_step() if there is ha 232 # arch_has_single_step() if there is hardware single-step support
263 # arch_has_block_step() if there is ha 233 # arch_has_block_step() if there is hardware block-step support
264 # asm/syscall.h supplying asm- 234 # asm/syscall.h supplying asm-generic/syscall.h interface
265 # linux/regset.h user_regset in 235 # linux/regset.h user_regset interfaces
266 # CORE_DUMP_USE_REGSET #define'd in l 236 # CORE_DUMP_USE_REGSET #define'd in linux/elf.h
267 # TIF_SYSCALL_TRACE calls ptrace_r 237 # TIF_SYSCALL_TRACE calls ptrace_report_syscall_{entry,exit}
268 # TIF_NOTIFY_RESUME calls resume_u 238 # TIF_NOTIFY_RESUME calls resume_user_mode_work()
269 # 239 #
270 config HAVE_ARCH_TRACEHOOK 240 config HAVE_ARCH_TRACEHOOK
271 bool 241 bool
272 242
273 config HAVE_DMA_CONTIGUOUS 243 config HAVE_DMA_CONTIGUOUS
274 bool 244 bool
275 245
276 config GENERIC_SMP_IDLE_THREAD 246 config GENERIC_SMP_IDLE_THREAD
277 bool 247 bool
278 248
279 config GENERIC_IDLE_POLL_SETUP 249 config GENERIC_IDLE_POLL_SETUP
280 bool 250 bool
281 251
282 config ARCH_HAS_FORTIFY_SOURCE 252 config ARCH_HAS_FORTIFY_SOURCE
283 bool 253 bool
284 help 254 help
285 An architecture should select this w 255 An architecture should select this when it can successfully
286 build and run with CONFIG_FORTIFY_SO 256 build and run with CONFIG_FORTIFY_SOURCE.
287 257
288 # 258 #
289 # Select if the arch provides a historic keepi 259 # Select if the arch provides a historic keepinit alias for the retain_initrd
290 # command line option 260 # command line option
291 # 261 #
292 config ARCH_HAS_KEEPINITRD 262 config ARCH_HAS_KEEPINITRD
293 bool 263 bool
294 264
295 # Select if arch has all set_memory_ro/rw/x/nx 265 # Select if arch has all set_memory_ro/rw/x/nx() functions in asm/cacheflush.h
296 config ARCH_HAS_SET_MEMORY 266 config ARCH_HAS_SET_MEMORY
297 bool 267 bool
298 268
299 # Select if arch has all set_direct_map_invali 269 # Select if arch has all set_direct_map_invalid/default() functions
300 config ARCH_HAS_SET_DIRECT_MAP 270 config ARCH_HAS_SET_DIRECT_MAP
301 bool 271 bool
302 272
303 # 273 #
304 # Select if the architecture provides the arch 274 # Select if the architecture provides the arch_dma_set_uncached symbol to
305 # either provide an uncached segment alias for 275 # either provide an uncached segment alias for a DMA allocation, or
306 # to remap the page tables in place. 276 # to remap the page tables in place.
307 # 277 #
308 config ARCH_HAS_DMA_SET_UNCACHED 278 config ARCH_HAS_DMA_SET_UNCACHED
309 bool 279 bool
310 280
311 # 281 #
312 # Select if the architectures provides the arc 282 # Select if the architectures provides the arch_dma_clear_uncached symbol
313 # to undo an in-place page table remap for unc 283 # to undo an in-place page table remap for uncached access.
314 # 284 #
315 config ARCH_HAS_DMA_CLEAR_UNCACHED 285 config ARCH_HAS_DMA_CLEAR_UNCACHED
316 bool 286 bool
317 287
318 config ARCH_HAS_CPU_FINALIZE_INIT !! 288 # Select if arch init_task must go in the __init_task_data section
>> 289 config ARCH_TASK_STRUCT_ON_STACK
319 bool 290 bool
320 291
321 # The architecture has a per-task state that i !! 292 # Select if arch has its private alloc_task_struct() function
322 config ARCH_HAS_CPU_PASID !! 293 config ARCH_TASK_STRUCT_ALLOCATOR
323 bool 294 bool
324 select IOMMU_MM_DATA <<
325 295
326 config HAVE_ARCH_THREAD_STRUCT_WHITELIST 296 config HAVE_ARCH_THREAD_STRUCT_WHITELIST
327 bool 297 bool
>> 298 depends on !ARCH_TASK_STRUCT_ALLOCATOR
328 help 299 help
329 An architecture should select this t 300 An architecture should select this to provide hardened usercopy
330 knowledge about what region of the t 301 knowledge about what region of the thread_struct should be
331 whitelisted for copying to userspace 302 whitelisted for copying to userspace. Normally this is only the
332 FPU registers. Specifically, arch_th 303 FPU registers. Specifically, arch_thread_struct_whitelist()
333 should be implemented. Without this, 304 should be implemented. Without this, the entire thread_struct
334 field in task_struct will be left wh 305 field in task_struct will be left whitelisted.
335 306
>> 307 # Select if arch has its private alloc_thread_stack() function
>> 308 config ARCH_THREAD_STACK_ALLOCATOR
>> 309 bool
>> 310
336 # Select if arch wants to size task_struct dyn 311 # Select if arch wants to size task_struct dynamically via arch_task_struct_size:
337 config ARCH_WANTS_DYNAMIC_TASK_STRUCT 312 config ARCH_WANTS_DYNAMIC_TASK_STRUCT
338 bool 313 bool
339 314
340 config ARCH_WANTS_NO_INSTR 315 config ARCH_WANTS_NO_INSTR
341 bool 316 bool
342 help 317 help
343 An architecture should select this i 318 An architecture should select this if the noinstr macro is being used on
344 functions to denote that the toolcha 319 functions to denote that the toolchain should avoid instrumenting such
345 functions and is required for correc 320 functions and is required for correctness.
346 321
347 config ARCH_32BIT_OFF_T 322 config ARCH_32BIT_OFF_T
348 bool 323 bool
349 depends on !64BIT 324 depends on !64BIT
350 help 325 help
351 All new 32-bit architectures should 326 All new 32-bit architectures should have 64-bit off_t type on
352 userspace side which corresponds to 327 userspace side which corresponds to the loff_t kernel type. This
353 is the requirement for modern ABIs. 328 is the requirement for modern ABIs. Some existing architectures
354 still support 32-bit off_t. This opt 329 still support 32-bit off_t. This option is enabled for all such
355 architectures explicitly. 330 architectures explicitly.
356 331
357 # Selected by 64 bit architectures which have 332 # Selected by 64 bit architectures which have a 32 bit f_tinode in struct ustat
358 config ARCH_32BIT_USTAT_F_TINODE 333 config ARCH_32BIT_USTAT_F_TINODE
359 bool 334 bool
360 335
361 config HAVE_ASM_MODVERSIONS 336 config HAVE_ASM_MODVERSIONS
362 bool 337 bool
363 help 338 help
364 This symbol should be selected by an 339 This symbol should be selected by an architecture if it provides
365 <asm/asm-prototypes.h> to support th 340 <asm/asm-prototypes.h> to support the module versioning for symbols
366 exported from assembly code. 341 exported from assembly code.
367 342
368 config HAVE_REGS_AND_STACK_ACCESS_API 343 config HAVE_REGS_AND_STACK_ACCESS_API
369 bool 344 bool
370 help 345 help
371 This symbol should be selected by an 346 This symbol should be selected by an architecture if it supports
372 the API needed to access registers a 347 the API needed to access registers and stack entries from pt_regs,
373 declared in asm/ptrace.h 348 declared in asm/ptrace.h
374 For example the kprobes-based event 349 For example the kprobes-based event tracer needs this API.
375 350
376 config HAVE_RSEQ 351 config HAVE_RSEQ
377 bool 352 bool
378 depends on HAVE_REGS_AND_STACK_ACCESS_ 353 depends on HAVE_REGS_AND_STACK_ACCESS_API
379 help 354 help
380 This symbol should be selected by an 355 This symbol should be selected by an architecture if it
381 supports an implementation of restar 356 supports an implementation of restartable sequences.
382 357
383 config HAVE_RUST <<
384 bool <<
385 help <<
386 This symbol should be selected by an <<
387 supports Rust. <<
388 <<
389 config HAVE_FUNCTION_ARG_ACCESS_API 358 config HAVE_FUNCTION_ARG_ACCESS_API
390 bool 359 bool
391 help 360 help
392 This symbol should be selected by an 361 This symbol should be selected by an architecture if it supports
393 the API needed to access function ar 362 the API needed to access function arguments from pt_regs,
394 declared in asm/ptrace.h 363 declared in asm/ptrace.h
395 364
396 config HAVE_HW_BREAKPOINT 365 config HAVE_HW_BREAKPOINT
397 bool 366 bool
398 depends on PERF_EVENTS 367 depends on PERF_EVENTS
399 368
400 config HAVE_MIXED_BREAKPOINTS_REGS 369 config HAVE_MIXED_BREAKPOINTS_REGS
401 bool 370 bool
402 depends on HAVE_HW_BREAKPOINT 371 depends on HAVE_HW_BREAKPOINT
403 help 372 help
404 Depending on the arch implementation 373 Depending on the arch implementation of hardware breakpoints,
405 some of them have separate registers 374 some of them have separate registers for data and instruction
406 breakpoints addresses, others have m 375 breakpoints addresses, others have mixed registers to store
407 them but define the access type in a 376 them but define the access type in a control register.
408 Select this option if your arch impl 377 Select this option if your arch implements breakpoints under the
409 latter fashion. 378 latter fashion.
410 379
411 config HAVE_USER_RETURN_NOTIFIER 380 config HAVE_USER_RETURN_NOTIFIER
412 bool 381 bool
413 382
414 config HAVE_PERF_EVENTS_NMI 383 config HAVE_PERF_EVENTS_NMI
415 bool 384 bool
416 help 385 help
417 System hardware can generate an NMI 386 System hardware can generate an NMI using the perf event
418 subsystem. Also has support for cal 387 subsystem. Also has support for calculating CPU cycle events
419 to determine how many clock cycles i 388 to determine how many clock cycles in a given period.
420 389
421 config HAVE_HARDLOCKUP_DETECTOR_PERF 390 config HAVE_HARDLOCKUP_DETECTOR_PERF
422 bool 391 bool
423 depends on HAVE_PERF_EVENTS_NMI 392 depends on HAVE_PERF_EVENTS_NMI
424 help 393 help
425 The arch chooses to use the generic 394 The arch chooses to use the generic perf-NMI-based hardlockup
426 detector. Must define HAVE_PERF_EVEN 395 detector. Must define HAVE_PERF_EVENTS_NMI.
427 396
428 config HAVE_HARDLOCKUP_DETECTOR_ARCH !! 397 config HAVE_NMI_WATCHDOG
>> 398 depends on HAVE_NMI
429 bool 399 bool
430 help 400 help
431 The arch provides its own hardlockup !! 401 The arch provides a low level NMI watchdog. It provides
432 of the generic ones. !! 402 asm/nmi.h, and defines its own arch_touch_nmi_watchdog().
433 403
434 It uses the same command line parame !! 404 config HAVE_HARDLOCKUP_DETECTOR_ARCH
435 as the generic hardlockup detectors. !! 405 bool
>> 406 select HAVE_NMI_WATCHDOG
>> 407 help
>> 408 The arch chooses to provide its own hardlockup detector, which is
>> 409 a superset of the HAVE_NMI_WATCHDOG. It also conforms to config
>> 410 interfaces and parameters provided by hardlockup detector subsystem.
436 411
437 config HAVE_PERF_REGS 412 config HAVE_PERF_REGS
438 bool 413 bool
439 help 414 help
440 Support selective register dumps for 415 Support selective register dumps for perf events. This includes
441 bit-mapping of each registers and a 416 bit-mapping of each registers and a unique architecture id.
442 417
443 config HAVE_PERF_USER_STACK_DUMP 418 config HAVE_PERF_USER_STACK_DUMP
444 bool 419 bool
445 help 420 help
446 Support user stack dumps for perf ev 421 Support user stack dumps for perf event samples. This needs
447 access to the user stack pointer whi 422 access to the user stack pointer which is not unified across
448 architectures. 423 architectures.
449 424
450 config HAVE_ARCH_JUMP_LABEL 425 config HAVE_ARCH_JUMP_LABEL
451 bool 426 bool
452 427
453 config HAVE_ARCH_JUMP_LABEL_RELATIVE 428 config HAVE_ARCH_JUMP_LABEL_RELATIVE
454 bool 429 bool
455 430
456 config MMU_GATHER_TABLE_FREE 431 config MMU_GATHER_TABLE_FREE
457 bool 432 bool
458 433
459 config MMU_GATHER_RCU_TABLE_FREE 434 config MMU_GATHER_RCU_TABLE_FREE
460 bool 435 bool
461 select MMU_GATHER_TABLE_FREE 436 select MMU_GATHER_TABLE_FREE
462 437
463 config MMU_GATHER_PAGE_SIZE 438 config MMU_GATHER_PAGE_SIZE
464 bool 439 bool
465 440
466 config MMU_GATHER_NO_RANGE 441 config MMU_GATHER_NO_RANGE
467 bool 442 bool
468 select MMU_GATHER_MERGE_VMAS 443 select MMU_GATHER_MERGE_VMAS
469 444
470 config MMU_GATHER_NO_FLUSH_CACHE 445 config MMU_GATHER_NO_FLUSH_CACHE
471 bool 446 bool
472 447
473 config MMU_GATHER_MERGE_VMAS 448 config MMU_GATHER_MERGE_VMAS
474 bool 449 bool
475 450
476 config MMU_GATHER_NO_GATHER 451 config MMU_GATHER_NO_GATHER
477 bool 452 bool
478 depends on MMU_GATHER_TABLE_FREE 453 depends on MMU_GATHER_TABLE_FREE
479 454
480 config ARCH_WANT_IRQS_OFF_ACTIVATE_MM 455 config ARCH_WANT_IRQS_OFF_ACTIVATE_MM
481 bool 456 bool
482 help 457 help
483 Temporary select until all architect 458 Temporary select until all architectures can be converted to have
484 irqs disabled over activate_mm. Arch 459 irqs disabled over activate_mm. Architectures that do IPI based TLB
485 shootdowns should enable this. 460 shootdowns should enable this.
486 461
487 # Use normal mm refcounting for MMU_LAZY_TLB k <<
488 # MMU_LAZY_TLB_REFCOUNT=n can improve the scal <<
489 # to/from kernel threads when the same mm is r <<
490 # multi-threaded application), by reducing con <<
491 # <<
492 # This can be disabled if the architecture ens <<
493 # "lazy tlb" beyond its final refcount (i.e., <<
494 # or its kernel page tables). This could be ar <<
495 # final exit(2) TLB flush, for example. <<
496 # <<
497 # To implement this, an arch *must*: <<
498 # Ensure the _lazy_tlb variants of mmgrab/mmdr <<
499 # the lazy tlb reference of a kthread's ->acti <<
500 # converted already). <<
501 config MMU_LAZY_TLB_REFCOUNT <<
502 def_bool y <<
503 depends on !MMU_LAZY_TLB_SHOOTDOWN <<
504 <<
505 # This option allows MMU_LAZY_TLB_REFCOUNT=n. <<
506 # mm as a lazy tlb beyond its last reference c <<
507 # users before the mm is deallocated. __mmdrop <<
508 # be using the mm as a lazy tlb, so that they <<
509 # init_mm for their active mm. mm_cpumask(mm) <<
510 # may be using mm as a lazy tlb mm. <<
511 # <<
512 # To implement this, an arch *must*: <<
513 # - At the time of the final mmdrop of the mm, <<
514 # at least all possible CPUs in which the mm <<
515 # - It must meet the requirements for MMU_LAZY <<
516 config MMU_LAZY_TLB_SHOOTDOWN <<
517 bool <<
518 <<
519 config ARCH_HAVE_NMI_SAFE_CMPXCHG 462 config ARCH_HAVE_NMI_SAFE_CMPXCHG
520 bool 463 bool
521 464
522 config ARCH_HAVE_EXTRA_ELF_NOTES <<
523 bool <<
524 help <<
525 An architecture should select this i <<
526 arch-specific ELF note section to co <<
527 functions: elf_coredump_extra_notes_ <<
528 elf_coredump_extra_notes_write() whi <<
529 dumper. <<
530 <<
531 config ARCH_HAS_NMI_SAFE_THIS_CPU_OPS <<
532 bool <<
533 <<
534 config HAVE_ALIGNED_STRUCT_PAGE 465 config HAVE_ALIGNED_STRUCT_PAGE
535 bool 466 bool
536 help 467 help
537 This makes sure that struct pages ar 468 This makes sure that struct pages are double word aligned and that
538 e.g. the SLUB allocator can perform 469 e.g. the SLUB allocator can perform double word atomic operations
539 on a struct page for better performa 470 on a struct page for better performance. However selecting this
540 might increase the size of a struct 471 might increase the size of a struct page by a word.
541 472
542 config HAVE_CMPXCHG_LOCAL 473 config HAVE_CMPXCHG_LOCAL
543 bool 474 bool
544 475
545 config HAVE_CMPXCHG_DOUBLE 476 config HAVE_CMPXCHG_DOUBLE
546 bool 477 bool
547 478
548 config ARCH_WEAK_RELEASE_ACQUIRE 479 config ARCH_WEAK_RELEASE_ACQUIRE
549 bool 480 bool
550 481
551 config ARCH_WANT_IPC_PARSE_VERSION 482 config ARCH_WANT_IPC_PARSE_VERSION
552 bool 483 bool
553 484
554 config ARCH_WANT_COMPAT_IPC_PARSE_VERSION 485 config ARCH_WANT_COMPAT_IPC_PARSE_VERSION
555 bool 486 bool
556 487
557 config ARCH_WANT_OLD_COMPAT_IPC 488 config ARCH_WANT_OLD_COMPAT_IPC
558 select ARCH_WANT_COMPAT_IPC_PARSE_VERS 489 select ARCH_WANT_COMPAT_IPC_PARSE_VERSION
559 bool 490 bool
560 491
561 config HAVE_ARCH_SECCOMP 492 config HAVE_ARCH_SECCOMP
562 bool 493 bool
563 help 494 help
564 An arch should select this symbol to 495 An arch should select this symbol to support seccomp mode 1 (the fixed
565 syscall policy), and must provide an 496 syscall policy), and must provide an overrides for __NR_seccomp_sigreturn,
566 and compat syscalls if the asm-gener 497 and compat syscalls if the asm-generic/seccomp.h defaults need adjustment:
567 - __NR_seccomp_read_32 498 - __NR_seccomp_read_32
568 - __NR_seccomp_write_32 499 - __NR_seccomp_write_32
569 - __NR_seccomp_exit_32 500 - __NR_seccomp_exit_32
570 - __NR_seccomp_sigreturn_32 501 - __NR_seccomp_sigreturn_32
571 502
572 config HAVE_ARCH_SECCOMP_FILTER 503 config HAVE_ARCH_SECCOMP_FILTER
573 bool 504 bool
574 select HAVE_ARCH_SECCOMP 505 select HAVE_ARCH_SECCOMP
575 help 506 help
576 An arch should select this symbol if 507 An arch should select this symbol if it provides all of these things:
577 - all the requirements for HAVE_ARCH 508 - all the requirements for HAVE_ARCH_SECCOMP
578 - syscall_get_arch() 509 - syscall_get_arch()
579 - syscall_get_arguments() 510 - syscall_get_arguments()
580 - syscall_rollback() 511 - syscall_rollback()
581 - syscall_set_return_value() 512 - syscall_set_return_value()
582 - SIGSYS siginfo_t support 513 - SIGSYS siginfo_t support
583 - secure_computing is called from a 514 - secure_computing is called from a ptrace_event()-safe context
584 - secure_computing return value is c 515 - secure_computing return value is checked and a return value of -1
585 results in the system call being s 516 results in the system call being skipped immediately.
586 - seccomp syscall wired up 517 - seccomp syscall wired up
587 - if !HAVE_SPARSE_SYSCALL_NR, have S 518 - if !HAVE_SPARSE_SYSCALL_NR, have SECCOMP_ARCH_NATIVE,
588 SECCOMP_ARCH_NATIVE_NR, SECCOMP_AR 519 SECCOMP_ARCH_NATIVE_NR, SECCOMP_ARCH_NATIVE_NAME defined. If
589 COMPAT is supported, have the SECC 520 COMPAT is supported, have the SECCOMP_ARCH_COMPAT* defines too.
590 521
591 config SECCOMP 522 config SECCOMP
592 prompt "Enable seccomp to safely execu 523 prompt "Enable seccomp to safely execute untrusted bytecode"
593 def_bool y 524 def_bool y
594 depends on HAVE_ARCH_SECCOMP 525 depends on HAVE_ARCH_SECCOMP
595 help 526 help
596 This kernel feature is useful for nu 527 This kernel feature is useful for number crunching applications
597 that may need to handle untrusted by 528 that may need to handle untrusted bytecode during their
598 execution. By using pipes or other t 529 execution. By using pipes or other transports made available
599 to the process as file descriptors s 530 to the process as file descriptors supporting the read/write
600 syscalls, it's possible to isolate t 531 syscalls, it's possible to isolate those applications in their
601 own address space using seccomp. Onc 532 own address space using seccomp. Once seccomp is enabled via
602 prctl(PR_SET_SECCOMP) or the seccomp 533 prctl(PR_SET_SECCOMP) or the seccomp() syscall, it cannot be
603 disabled and the task is only allowe 534 disabled and the task is only allowed to execute a few safe
604 syscalls defined by each seccomp mod 535 syscalls defined by each seccomp mode.
605 536
606 If unsure, say Y. 537 If unsure, say Y.
607 538
608 config SECCOMP_FILTER 539 config SECCOMP_FILTER
609 def_bool y 540 def_bool y
610 depends on HAVE_ARCH_SECCOMP_FILTER && 541 depends on HAVE_ARCH_SECCOMP_FILTER && SECCOMP && NET
611 help 542 help
612 Enable tasks to build secure computi 543 Enable tasks to build secure computing environments defined
613 in terms of Berkeley Packet Filter p 544 in terms of Berkeley Packet Filter programs which implement
614 task-defined system call filtering p 545 task-defined system call filtering polices.
615 546
616 See Documentation/userspace-api/secc 547 See Documentation/userspace-api/seccomp_filter.rst for details.
617 548
618 config SECCOMP_CACHE_DEBUG 549 config SECCOMP_CACHE_DEBUG
619 bool "Show seccomp filter cache status 550 bool "Show seccomp filter cache status in /proc/pid/seccomp_cache"
620 depends on SECCOMP_FILTER && !HAVE_SPA 551 depends on SECCOMP_FILTER && !HAVE_SPARSE_SYSCALL_NR
621 depends on PROC_FS 552 depends on PROC_FS
622 help 553 help
623 This enables the /proc/pid/seccomp_c 554 This enables the /proc/pid/seccomp_cache interface to monitor
624 seccomp cache data. The file format 555 seccomp cache data. The file format is subject to change. Reading
625 the file requires CAP_SYS_ADMIN. 556 the file requires CAP_SYS_ADMIN.
626 557
627 This option is for debugging only. E 558 This option is for debugging only. Enabling presents the risk that
628 an adversary may be able to infer th 559 an adversary may be able to infer the seccomp filter logic.
629 560
630 If unsure, say N. 561 If unsure, say N.
631 562
632 config HAVE_ARCH_STACKLEAK 563 config HAVE_ARCH_STACKLEAK
633 bool 564 bool
634 help 565 help
635 An architecture should select this i 566 An architecture should select this if it has the code which
636 fills the used part of the kernel st 567 fills the used part of the kernel stack with the STACKLEAK_POISON
637 value before returning from system c 568 value before returning from system calls.
638 569
639 config HAVE_STACKPROTECTOR 570 config HAVE_STACKPROTECTOR
640 bool 571 bool
641 help 572 help
642 An arch should select this symbol if 573 An arch should select this symbol if:
643 - it has implemented a stack canary 574 - it has implemented a stack canary (e.g. __stack_chk_guard)
644 575
645 config STACKPROTECTOR 576 config STACKPROTECTOR
646 bool "Stack Protector buffer overflow 577 bool "Stack Protector buffer overflow detection"
647 depends on HAVE_STACKPROTECTOR 578 depends on HAVE_STACKPROTECTOR
648 depends on $(cc-option,-fstack-protect 579 depends on $(cc-option,-fstack-protector)
649 default y 580 default y
650 help 581 help
651 This option turns on the "stack-prot 582 This option turns on the "stack-protector" GCC feature. This
652 feature puts, at the beginning of fu 583 feature puts, at the beginning of functions, a canary value on
653 the stack just before the return add 584 the stack just before the return address, and validates
654 the value just before actually retur 585 the value just before actually returning. Stack based buffer
655 overflows (that need to overwrite th 586 overflows (that need to overwrite this return address) now also
656 overwrite the canary, which gets det 587 overwrite the canary, which gets detected and the attack is then
657 neutralized via a kernel panic. 588 neutralized via a kernel panic.
658 589
659 Functions will have the stack-protec 590 Functions will have the stack-protector canary logic added if they
660 have an 8-byte or larger character a 591 have an 8-byte or larger character array on the stack.
661 592
662 This feature requires gcc version 4. 593 This feature requires gcc version 4.2 or above, or a distribution
663 gcc with the feature backported ("-f 594 gcc with the feature backported ("-fstack-protector").
664 595
665 On an x86 "defconfig" build, this fe 596 On an x86 "defconfig" build, this feature adds canary checks to
666 about 3% of all kernel functions, wh 597 about 3% of all kernel functions, which increases kernel code size
667 by about 0.3%. 598 by about 0.3%.
668 599
669 config STACKPROTECTOR_STRONG 600 config STACKPROTECTOR_STRONG
670 bool "Strong Stack Protector" 601 bool "Strong Stack Protector"
671 depends on STACKPROTECTOR 602 depends on STACKPROTECTOR
672 depends on $(cc-option,-fstack-protect 603 depends on $(cc-option,-fstack-protector-strong)
673 default y 604 default y
674 help 605 help
675 Functions will have the stack-protec 606 Functions will have the stack-protector canary logic added in any
676 of the following conditions: 607 of the following conditions:
677 608
678 - local variable's address used as p 609 - local variable's address used as part of the right hand side of an
679 assignment or function argument 610 assignment or function argument
680 - local variable is an array (or uni 611 - local variable is an array (or union containing an array),
681 regardless of array type or length 612 regardless of array type or length
682 - uses register local variables 613 - uses register local variables
683 614
684 This feature requires gcc version 4. 615 This feature requires gcc version 4.9 or above, or a distribution
685 gcc with the feature backported ("-f 616 gcc with the feature backported ("-fstack-protector-strong").
686 617
687 On an x86 "defconfig" build, this fe 618 On an x86 "defconfig" build, this feature adds canary checks to
688 about 20% of all kernel functions, w 619 about 20% of all kernel functions, which increases the kernel code
689 size by about 2%. 620 size by about 2%.
690 621
691 config ARCH_SUPPORTS_SHADOW_CALL_STACK 622 config ARCH_SUPPORTS_SHADOW_CALL_STACK
692 bool 623 bool
693 help 624 help
694 An architecture should select this i 625 An architecture should select this if it supports the compiler's
695 Shadow Call Stack and implements run 626 Shadow Call Stack and implements runtime support for shadow stack
696 switching. 627 switching.
697 628
698 config SHADOW_CALL_STACK 629 config SHADOW_CALL_STACK
699 bool "Shadow Call Stack" 630 bool "Shadow Call Stack"
700 depends on ARCH_SUPPORTS_SHADOW_CALL_S 631 depends on ARCH_SUPPORTS_SHADOW_CALL_STACK
701 depends on DYNAMIC_FTRACE_WITH_ARGS || 632 depends on DYNAMIC_FTRACE_WITH_ARGS || DYNAMIC_FTRACE_WITH_REGS || !FUNCTION_GRAPH_TRACER
702 depends on MMU <<
703 help 633 help
704 This option enables the compiler's S 634 This option enables the compiler's Shadow Call Stack, which
705 uses a shadow stack to protect funct 635 uses a shadow stack to protect function return addresses from
706 being overwritten by an attacker. Mo 636 being overwritten by an attacker. More information can be found
707 in the compiler's documentation: 637 in the compiler's documentation:
708 638
709 - Clang: https://clang.llvm.org/docs 639 - Clang: https://clang.llvm.org/docs/ShadowCallStack.html
710 - GCC: https://gcc.gnu.org/onlinedoc 640 - GCC: https://gcc.gnu.org/onlinedocs/gcc/Instrumentation-Options.html#Instrumentation-Options
711 641
712 Note that security guarantees in the 642 Note that security guarantees in the kernel differ from the
713 ones documented for user space. The 643 ones documented for user space. The kernel must store addresses
714 of shadow stacks in memory, which me 644 of shadow stacks in memory, which means an attacker capable of
715 reading and writing arbitrary memory 645 reading and writing arbitrary memory may be able to locate them
716 and hijack control flow by modifying 646 and hijack control flow by modifying the stacks.
717 647
718 config DYNAMIC_SCS <<
719 bool <<
720 help <<
721 Set by the arch code if it relies on <<
722 shadow call stack push and pop instr <<
723 compiler. <<
724 <<
725 config LTO 648 config LTO
726 bool 649 bool
727 help 650 help
728 Selected if the kernel will be built 651 Selected if the kernel will be built using the compiler's LTO feature.
729 652
730 config LTO_CLANG 653 config LTO_CLANG
731 bool 654 bool
732 select LTO 655 select LTO
733 help 656 help
734 Selected if the kernel will be built 657 Selected if the kernel will be built using Clang's LTO feature.
735 658
736 config ARCH_SUPPORTS_LTO_CLANG 659 config ARCH_SUPPORTS_LTO_CLANG
737 bool 660 bool
738 help 661 help
739 An architecture should select this o 662 An architecture should select this option if it supports:
740 - compiling with Clang, 663 - compiling with Clang,
741 - compiling inline assembly with Cla 664 - compiling inline assembly with Clang's integrated assembler,
742 - and linking with LLD. 665 - and linking with LLD.
743 666
744 config ARCH_SUPPORTS_LTO_CLANG_THIN 667 config ARCH_SUPPORTS_LTO_CLANG_THIN
745 bool 668 bool
746 help 669 help
747 An architecture should select this o 670 An architecture should select this option if it can support Clang's
748 ThinLTO mode. 671 ThinLTO mode.
749 672
750 config HAS_LTO_CLANG 673 config HAS_LTO_CLANG
751 def_bool y 674 def_bool y
752 depends on CC_IS_CLANG && LD_IS_LLD && 675 depends on CC_IS_CLANG && LD_IS_LLD && AS_IS_LLVM
753 depends on $(success,$(NM) --help | he 676 depends on $(success,$(NM) --help | head -n 1 | grep -qi llvm)
754 depends on $(success,$(AR) --help | he 677 depends on $(success,$(AR) --help | head -n 1 | grep -qi llvm)
755 depends on ARCH_SUPPORTS_LTO_CLANG 678 depends on ARCH_SUPPORTS_LTO_CLANG
756 depends on !FTRACE_MCOUNT_USE_RECORDMC 679 depends on !FTRACE_MCOUNT_USE_RECORDMCOUNT
757 # https://github.com/ClangBuiltLinux/l !! 680 depends on !KASAN || KASAN_HW_TAGS
758 depends on (!KASAN || KASAN_HW_TAGS || <<
759 depends on (!KCOV || CLANG_VERSION >= <<
760 depends on !GCOV_KERNEL 681 depends on !GCOV_KERNEL
761 help 682 help
762 The compiler and Kconfig options sup 683 The compiler and Kconfig options support building with Clang's
763 LTO. 684 LTO.
764 685
765 choice 686 choice
766 prompt "Link Time Optimization (LTO)" 687 prompt "Link Time Optimization (LTO)"
767 default LTO_NONE 688 default LTO_NONE
768 help 689 help
769 This option enables Link Time Optimi 690 This option enables Link Time Optimization (LTO), which allows the
770 compiler to optimize binaries global 691 compiler to optimize binaries globally.
771 692
772 If unsure, select LTO_NONE. Note tha 693 If unsure, select LTO_NONE. Note that LTO is very resource-intensive
773 so it's disabled by default. 694 so it's disabled by default.
774 695
775 config LTO_NONE 696 config LTO_NONE
776 bool "None" 697 bool "None"
777 help 698 help
778 Build the kernel normally, without L 699 Build the kernel normally, without Link Time Optimization (LTO).
779 700
780 config LTO_CLANG_FULL 701 config LTO_CLANG_FULL
781 bool "Clang Full LTO (EXPERIMENTAL)" 702 bool "Clang Full LTO (EXPERIMENTAL)"
782 depends on HAS_LTO_CLANG 703 depends on HAS_LTO_CLANG
783 depends on !COMPILE_TEST 704 depends on !COMPILE_TEST
784 select LTO_CLANG 705 select LTO_CLANG
785 help 706 help
786 This option enables Clang's full Lin !! 707 This option enables Clang's full Link Time Optimization (LTO), which
787 allows the compiler to optimize the !! 708 allows the compiler to optimize the kernel globally. If you enable
788 this option, the compiler generates !! 709 this option, the compiler generates LLVM bitcode instead of ELF
789 object files, and the actual compila !! 710 object files, and the actual compilation from bitcode happens at
790 the LTO link step, which may take se !! 711 the LTO link step, which may take several minutes depending on the
791 kernel configuration. More informati !! 712 kernel configuration. More information can be found from LLVM's
792 documentation: !! 713 documentation:
793 714
794 https://llvm.org/docs/LinkTimeOpti 715 https://llvm.org/docs/LinkTimeOptimization.html
795 716
796 During link time, this option can us 717 During link time, this option can use a large amount of RAM, and
797 may take much longer than the ThinLT 718 may take much longer than the ThinLTO option.
798 719
799 config LTO_CLANG_THIN 720 config LTO_CLANG_THIN
800 bool "Clang ThinLTO (EXPERIMENTAL)" 721 bool "Clang ThinLTO (EXPERIMENTAL)"
801 depends on HAS_LTO_CLANG && ARCH_SUPPO 722 depends on HAS_LTO_CLANG && ARCH_SUPPORTS_LTO_CLANG_THIN
802 select LTO_CLANG 723 select LTO_CLANG
803 help 724 help
804 This option enables Clang's ThinLTO, 725 This option enables Clang's ThinLTO, which allows for parallel
805 optimization and faster incremental 726 optimization and faster incremental compiles compared to the
806 CONFIG_LTO_CLANG_FULL option. More i 727 CONFIG_LTO_CLANG_FULL option. More information can be found
807 from Clang's documentation: 728 from Clang's documentation:
808 729
809 https://clang.llvm.org/docs/ThinLT 730 https://clang.llvm.org/docs/ThinLTO.html
810 731
811 If unsure, say Y. 732 If unsure, say Y.
812 endchoice 733 endchoice
813 734
814 config ARCH_SUPPORTS_CFI_CLANG 735 config ARCH_SUPPORTS_CFI_CLANG
815 bool 736 bool
816 help 737 help
817 An architecture should select this o 738 An architecture should select this option if it can support Clang's
818 Control-Flow Integrity (CFI) checkin 739 Control-Flow Integrity (CFI) checking.
819 740
820 config ARCH_USES_CFI_TRAPS <<
821 bool <<
822 <<
823 config CFI_CLANG 741 config CFI_CLANG
824 bool "Use Clang's Control Flow Integri 742 bool "Use Clang's Control Flow Integrity (CFI)"
825 depends on ARCH_SUPPORTS_CFI_CLANG !! 743 depends on LTO_CLANG && ARCH_SUPPORTS_CFI_CLANG
826 depends on $(cc-option,-fsanitize=kcfi !! 744 depends on CLANG_VERSION >= 140000
>> 745 select KALLSYMS
827 help 746 help
828 This option enables Clang's forward- !! 747 This option enables Clang’s forward-edge Control Flow Integrity
829 (CFI) checking, where the compiler i 748 (CFI) checking, where the compiler injects a runtime check to each
830 indirect function call to ensure the 749 indirect function call to ensure the target is a valid function with
831 the correct static type. This restri 750 the correct static type. This restricts possible call targets and
832 makes it more difficult for an attac 751 makes it more difficult for an attacker to exploit bugs that allow
833 the modification of stored function 752 the modification of stored function pointers. More information can be
834 found from Clang's documentation: 753 found from Clang's documentation:
835 754
836 https://clang.llvm.org/docs/Contro 755 https://clang.llvm.org/docs/ControlFlowIntegrity.html
837 756
838 config CFI_ICALL_NORMALIZE_INTEGERS !! 757 config CFI_CLANG_SHADOW
839 bool "Normalize CFI tags for integers" !! 758 bool "Use CFI shadow to speed up cross-module checks"
840 depends on CFI_CLANG !! 759 default y
841 depends on HAVE_CFI_ICALL_NORMALIZE_IN !! 760 depends on CFI_CLANG && MODULES
842 help 761 help
843 This option normalizes the CFI tags !! 762 If you select this option, the kernel builds a fast look-up table of
844 integer types of the same size and s !! 763 CFI check functions in loaded modules to reduce performance overhead.
845 tag. <<
846 <<
847 The option is separate from CONFIG_R <<
848 When working with build systems that <<
849 convenient to be able to turn on thi <<
850 turned on. <<
851 <<
852 This option is necessary for using C <<
853 <<
854 config HAVE_CFI_ICALL_NORMALIZE_INTEGERS_CLANG <<
855 def_bool y <<
856 depends on $(cc-option,-fsanitize=kcfi <<
857 # With GCOV/KASAN we need this fix: ht <<
858 depends on CLANG_VERSION >= 190103 || <<
859 764
860 config HAVE_CFI_ICALL_NORMALIZE_INTEGERS_RUSTC !! 765 If unsure, say Y.
861 def_bool y <<
862 depends on HAVE_CFI_ICALL_NORMALIZE_IN <<
863 depends on RUSTC_VERSION >= 107900 <<
864 # With GCOV/KASAN we need this fix: ht <<
865 depends on (RUSTC_LLVM_VERSION >= 1901 <<
866 (!GCOV_KERNEL && !KASAN_GENERI <<
867 766
868 config CFI_PERMISSIVE 767 config CFI_PERMISSIVE
869 bool "Use CFI in permissive mode" 768 bool "Use CFI in permissive mode"
870 depends on CFI_CLANG 769 depends on CFI_CLANG
871 help 770 help
872 When selected, Control Flow Integrit 771 When selected, Control Flow Integrity (CFI) violations result in a
873 warning instead of a kernel panic. T 772 warning instead of a kernel panic. This option should only be used
874 for finding indirect call type misma 773 for finding indirect call type mismatches during development.
875 774
876 If unsure, say N. 775 If unsure, say N.
877 776
878 config HAVE_ARCH_WITHIN_STACK_FRAMES 777 config HAVE_ARCH_WITHIN_STACK_FRAMES
879 bool 778 bool
880 help 779 help
881 An architecture should select this i 780 An architecture should select this if it can walk the kernel stack
882 frames to determine if an object is 781 frames to determine if an object is part of either the arguments
883 or local variables (i.e. that it exc 782 or local variables (i.e. that it excludes saved return addresses,
884 and similar) by implementing an inli 783 and similar) by implementing an inline arch_within_stack_frames(),
885 which is used by CONFIG_HARDENED_USE 784 which is used by CONFIG_HARDENED_USERCOPY.
886 785
887 config HAVE_CONTEXT_TRACKING_USER 786 config HAVE_CONTEXT_TRACKING_USER
888 bool 787 bool
889 help 788 help
890 Provide kernel/user boundaries probe 789 Provide kernel/user boundaries probes necessary for subsystems
891 that need it, such as userspace RCU 790 that need it, such as userspace RCU extended quiescent state.
892 Syscalls need to be wrapped inside u 791 Syscalls need to be wrapped inside user_exit()-user_enter(), either
893 optimized behind static key or throu 792 optimized behind static key or through the slow path using TIF_NOHZ
894 flag. Exceptions handlers must be wr 793 flag. Exceptions handlers must be wrapped as well. Irqs are already
895 protected inside ct_irq_enter/ct_irq 794 protected inside ct_irq_enter/ct_irq_exit() but preemption or signal
896 handling on irq exit still need to b 795 handling on irq exit still need to be protected.
897 796
898 config HAVE_CONTEXT_TRACKING_USER_OFFSTACK 797 config HAVE_CONTEXT_TRACKING_USER_OFFSTACK
899 bool 798 bool
900 help 799 help
901 Architecture neither relies on excep 800 Architecture neither relies on exception_enter()/exception_exit()
902 nor on schedule_user(). Also preempt 801 nor on schedule_user(). Also preempt_schedule_notrace() and
903 preempt_schedule_irq() can't be call 802 preempt_schedule_irq() can't be called in a preemptible section
904 while context tracking is CT_STATE_U !! 803 while context tracking is CONTEXT_USER. This feature reflects a sane
905 entry implementation where the follo 804 entry implementation where the following requirements are met on
906 critical entry code, ie: before user 805 critical entry code, ie: before user_exit() or after user_enter():
907 806
908 - Critical entry code isn't preempti 807 - Critical entry code isn't preemptible (or better yet:
909 not interruptible). 808 not interruptible).
910 - No use of RCU read side critical s 809 - No use of RCU read side critical sections, unless ct_nmi_enter()
911 got called. 810 got called.
912 - No use of instrumentation, unless 811 - No use of instrumentation, unless instrumentation_begin() got
913 called. 812 called.
914 813
915 config HAVE_TIF_NOHZ 814 config HAVE_TIF_NOHZ
916 bool 815 bool
917 help 816 help
918 Arch relies on TIF_NOHZ and syscall 817 Arch relies on TIF_NOHZ and syscall slow path to implement context
919 tracking calls to user_enter()/user_ 818 tracking calls to user_enter()/user_exit().
920 819
921 config HAVE_VIRT_CPU_ACCOUNTING 820 config HAVE_VIRT_CPU_ACCOUNTING
922 bool 821 bool
923 822
924 config HAVE_VIRT_CPU_ACCOUNTING_IDLE 823 config HAVE_VIRT_CPU_ACCOUNTING_IDLE
925 bool 824 bool
926 help 825 help
927 Architecture has its own way to acco 826 Architecture has its own way to account idle CPU time and therefore
928 doesn't implement vtime_account_idle 827 doesn't implement vtime_account_idle().
929 828
930 config ARCH_HAS_SCALED_CPUTIME 829 config ARCH_HAS_SCALED_CPUTIME
931 bool 830 bool
932 831
933 config HAVE_VIRT_CPU_ACCOUNTING_GEN 832 config HAVE_VIRT_CPU_ACCOUNTING_GEN
934 bool 833 bool
935 default y if 64BIT 834 default y if 64BIT
936 help 835 help
937 With VIRT_CPU_ACCOUNTING_GEN, cputim 836 With VIRT_CPU_ACCOUNTING_GEN, cputime_t becomes 64-bit.
938 Before enabling this option, arch co 837 Before enabling this option, arch code must be audited
939 to ensure there are no races in conc 838 to ensure there are no races in concurrent read/write of
940 cputime_t. For example, reading/writ 839 cputime_t. For example, reading/writing 64-bit cputime_t on
941 some 32-bit arches may require multi 840 some 32-bit arches may require multiple accesses, so proper
942 locking is needed to protect against 841 locking is needed to protect against concurrent accesses.
943 842
944 config HAVE_IRQ_TIME_ACCOUNTING 843 config HAVE_IRQ_TIME_ACCOUNTING
945 bool 844 bool
946 help 845 help
947 Archs need to ensure they use a high 846 Archs need to ensure they use a high enough resolution clock to
948 support irq time accounting and then 847 support irq time accounting and then call enable_sched_clock_irqtime().
949 848
950 config HAVE_MOVE_PUD 849 config HAVE_MOVE_PUD
951 bool 850 bool
952 help 851 help
953 Architectures that select this are a 852 Architectures that select this are able to move page tables at the
954 PUD level. If there are only 3 page 853 PUD level. If there are only 3 page table levels, the move effectively
955 happens at the PGD level. 854 happens at the PGD level.
956 855
957 config HAVE_MOVE_PMD 856 config HAVE_MOVE_PMD
958 bool 857 bool
959 help 858 help
960 Archs that select this are able to m 859 Archs that select this are able to move page tables at the PMD level.
961 860
962 config HAVE_ARCH_TRANSPARENT_HUGEPAGE 861 config HAVE_ARCH_TRANSPARENT_HUGEPAGE
963 bool 862 bool
964 863
965 config HAVE_ARCH_TRANSPARENT_HUGEPAGE_PUD 864 config HAVE_ARCH_TRANSPARENT_HUGEPAGE_PUD
966 bool 865 bool
967 866
968 config HAVE_ARCH_HUGE_VMAP 867 config HAVE_ARCH_HUGE_VMAP
969 bool 868 bool
970 869
971 # 870 #
972 # Archs that select this would be capable of 871 # Archs that select this would be capable of PMD-sized vmaps (i.e.,
973 # arch_vmap_pmd_supported() returns true). Th 872 # arch_vmap_pmd_supported() returns true). The VM_ALLOW_HUGE_VMAP flag
974 # must be used to enable allocations to use h 873 # must be used to enable allocations to use hugepages.
975 # 874 #
976 config HAVE_ARCH_HUGE_VMALLOC 875 config HAVE_ARCH_HUGE_VMALLOC
977 depends on HAVE_ARCH_HUGE_VMAP 876 depends on HAVE_ARCH_HUGE_VMAP
978 bool 877 bool
979 878
980 config ARCH_WANT_HUGE_PMD_SHARE 879 config ARCH_WANT_HUGE_PMD_SHARE
981 bool 880 bool
982 881
983 # Archs that want to use pmd_mkwrite on kernel <<
984 # if there are no userspace memory management <<
985 config ARCH_WANT_KERNEL_PMD_MKWRITE <<
986 bool <<
987 <<
988 config ARCH_WANT_PMD_MKWRITE <<
989 def_bool TRANSPARENT_HUGEPAGE || ARCH_ <<
990 <<
991 config HAVE_ARCH_SOFT_DIRTY 882 config HAVE_ARCH_SOFT_DIRTY
992 bool 883 bool
993 884
994 config HAVE_MOD_ARCH_SPECIFIC 885 config HAVE_MOD_ARCH_SPECIFIC
995 bool 886 bool
996 help 887 help
997 The arch uses struct mod_arch_specif 888 The arch uses struct mod_arch_specific to store data. Many arches
998 just need a simple module loader wit 889 just need a simple module loader without arch specific data - those
999 should not enable this. 890 should not enable this.
1000 891
1001 config MODULES_USE_ELF_RELA 892 config MODULES_USE_ELF_RELA
1002 bool 893 bool
1003 help 894 help
1004 Modules only use ELF RELA relocatio 895 Modules only use ELF RELA relocations. Modules with ELF REL
1005 relocations will give an error. 896 relocations will give an error.
1006 897
1007 config MODULES_USE_ELF_REL 898 config MODULES_USE_ELF_REL
1008 bool 899 bool
1009 help 900 help
1010 Modules only use ELF REL relocation 901 Modules only use ELF REL relocations. Modules with ELF RELA
1011 relocations will give an error. 902 relocations will give an error.
1012 903
1013 config ARCH_WANTS_MODULES_DATA_IN_VMALLOC 904 config ARCH_WANTS_MODULES_DATA_IN_VMALLOC
1014 bool 905 bool
1015 help 906 help
1016 For architectures like powerpc/32 w 907 For architectures like powerpc/32 which have constraints on module
1017 allocation and need to allocate mod 908 allocation and need to allocate module data outside of module area.
1018 909
1019 config ARCH_WANTS_EXECMEM_LATE <<
1020 bool <<
1021 help <<
1022 For architectures that do not alloc <<
1023 boot, but rather require its initia <<
1024 enough entropy for module space ran <<
1025 arm64. <<
1026 <<
1027 config HAVE_IRQ_EXIT_ON_IRQ_STACK 910 config HAVE_IRQ_EXIT_ON_IRQ_STACK
1028 bool 911 bool
1029 help 912 help
1030 Architecture doesn't only execute t 913 Architecture doesn't only execute the irq handler on the irq stack
1031 but also irq_exit(). This way we ca 914 but also irq_exit(). This way we can process softirqs on this irq
1032 stack instead of switching to a new 915 stack instead of switching to a new one when we call __do_softirq()
1033 in the end of an hardirq. 916 in the end of an hardirq.
1034 This spares a stack switch and impr 917 This spares a stack switch and improves cache usage on softirq
1035 processing. 918 processing.
1036 919
1037 config HAVE_SOFTIRQ_ON_OWN_STACK 920 config HAVE_SOFTIRQ_ON_OWN_STACK
1038 bool 921 bool
1039 help 922 help
1040 Architecture provides a function to 923 Architecture provides a function to run __do_softirq() on a
1041 separate stack. 924 separate stack.
1042 925
1043 config SOFTIRQ_ON_OWN_STACK 926 config SOFTIRQ_ON_OWN_STACK
1044 def_bool HAVE_SOFTIRQ_ON_OWN_STACK && 927 def_bool HAVE_SOFTIRQ_ON_OWN_STACK && !PREEMPT_RT
1045 928
1046 config ALTERNATE_USER_ADDRESS_SPACE 929 config ALTERNATE_USER_ADDRESS_SPACE
1047 bool 930 bool
1048 help 931 help
1049 Architectures set this when the CPU 932 Architectures set this when the CPU uses separate address
1050 spaces for kernel and user space po 933 spaces for kernel and user space pointers. In this case, the
1051 access_ok() check on a __user point 934 access_ok() check on a __user pointer is skipped.
1052 935
1053 config PGTABLE_LEVELS 936 config PGTABLE_LEVELS
1054 int 937 int
1055 default 2 938 default 2
1056 939
1057 config ARCH_HAS_ELF_RANDOMIZE 940 config ARCH_HAS_ELF_RANDOMIZE
1058 bool 941 bool
1059 help 942 help
1060 An architecture supports choosing r 943 An architecture supports choosing randomized locations for
1061 stack, mmap, brk, and ET_DYN. Defin 944 stack, mmap, brk, and ET_DYN. Defined functions:
1062 - arch_mmap_rnd() 945 - arch_mmap_rnd()
1063 - arch_randomize_brk() 946 - arch_randomize_brk()
1064 947
1065 config HAVE_ARCH_MMAP_RND_BITS 948 config HAVE_ARCH_MMAP_RND_BITS
1066 bool 949 bool
1067 help 950 help
1068 An arch should select this symbol i 951 An arch should select this symbol if it supports setting a variable
1069 number of bits for use in establish 952 number of bits for use in establishing the base address for mmap
1070 allocations, has MMU enabled and pr 953 allocations, has MMU enabled and provides values for both:
1071 - ARCH_MMAP_RND_BITS_MIN 954 - ARCH_MMAP_RND_BITS_MIN
1072 - ARCH_MMAP_RND_BITS_MAX 955 - ARCH_MMAP_RND_BITS_MAX
1073 956
1074 config HAVE_EXIT_THREAD 957 config HAVE_EXIT_THREAD
1075 bool 958 bool
1076 help 959 help
1077 An architecture implements exit_thr 960 An architecture implements exit_thread.
1078 961
1079 config ARCH_MMAP_RND_BITS_MIN 962 config ARCH_MMAP_RND_BITS_MIN
1080 int 963 int
1081 964
1082 config ARCH_MMAP_RND_BITS_MAX 965 config ARCH_MMAP_RND_BITS_MAX
1083 int 966 int
1084 967
1085 config ARCH_MMAP_RND_BITS_DEFAULT 968 config ARCH_MMAP_RND_BITS_DEFAULT
1086 int 969 int
1087 970
1088 config ARCH_MMAP_RND_BITS 971 config ARCH_MMAP_RND_BITS
1089 int "Number of bits to use for ASLR o 972 int "Number of bits to use for ASLR of mmap base address" if EXPERT
1090 range ARCH_MMAP_RND_BITS_MIN ARCH_MMA 973 range ARCH_MMAP_RND_BITS_MIN ARCH_MMAP_RND_BITS_MAX
1091 default ARCH_MMAP_RND_BITS_DEFAULT if 974 default ARCH_MMAP_RND_BITS_DEFAULT if ARCH_MMAP_RND_BITS_DEFAULT
1092 default ARCH_MMAP_RND_BITS_MIN 975 default ARCH_MMAP_RND_BITS_MIN
1093 depends on HAVE_ARCH_MMAP_RND_BITS 976 depends on HAVE_ARCH_MMAP_RND_BITS
1094 help 977 help
1095 This value can be used to select th 978 This value can be used to select the number of bits to use to
1096 determine the random offset to the 979 determine the random offset to the base address of vma regions
1097 resulting from mmap allocations. Th 980 resulting from mmap allocations. This value will be bounded
1098 by the architecture's minimum and m 981 by the architecture's minimum and maximum supported values.
1099 982
1100 This value can be changed after boo 983 This value can be changed after boot using the
1101 /proc/sys/vm/mmap_rnd_bits tunable 984 /proc/sys/vm/mmap_rnd_bits tunable
1102 985
1103 config HAVE_ARCH_MMAP_RND_COMPAT_BITS 986 config HAVE_ARCH_MMAP_RND_COMPAT_BITS
1104 bool 987 bool
1105 help 988 help
1106 An arch should select this symbol i 989 An arch should select this symbol if it supports running applications
1107 in compatibility mode, supports set 990 in compatibility mode, supports setting a variable number of bits for
1108 use in establishing the base addres 991 use in establishing the base address for mmap allocations, has MMU
1109 enabled and provides values for bot 992 enabled and provides values for both:
1110 - ARCH_MMAP_RND_COMPAT_BITS_MIN 993 - ARCH_MMAP_RND_COMPAT_BITS_MIN
1111 - ARCH_MMAP_RND_COMPAT_BITS_MAX 994 - ARCH_MMAP_RND_COMPAT_BITS_MAX
1112 995
1113 config ARCH_MMAP_RND_COMPAT_BITS_MIN 996 config ARCH_MMAP_RND_COMPAT_BITS_MIN
1114 int 997 int
1115 998
1116 config ARCH_MMAP_RND_COMPAT_BITS_MAX 999 config ARCH_MMAP_RND_COMPAT_BITS_MAX
1117 int 1000 int
1118 1001
1119 config ARCH_MMAP_RND_COMPAT_BITS_DEFAULT 1002 config ARCH_MMAP_RND_COMPAT_BITS_DEFAULT
1120 int 1003 int
1121 1004
1122 config ARCH_MMAP_RND_COMPAT_BITS 1005 config ARCH_MMAP_RND_COMPAT_BITS
1123 int "Number of bits to use for ASLR o 1006 int "Number of bits to use for ASLR of mmap base address for compatible applications" if EXPERT
1124 range ARCH_MMAP_RND_COMPAT_BITS_MIN A 1007 range ARCH_MMAP_RND_COMPAT_BITS_MIN ARCH_MMAP_RND_COMPAT_BITS_MAX
1125 default ARCH_MMAP_RND_COMPAT_BITS_DEF 1008 default ARCH_MMAP_RND_COMPAT_BITS_DEFAULT if ARCH_MMAP_RND_COMPAT_BITS_DEFAULT
1126 default ARCH_MMAP_RND_COMPAT_BITS_MIN 1009 default ARCH_MMAP_RND_COMPAT_BITS_MIN
1127 depends on HAVE_ARCH_MMAP_RND_COMPAT_ 1010 depends on HAVE_ARCH_MMAP_RND_COMPAT_BITS
1128 help 1011 help
1129 This value can be used to select th 1012 This value can be used to select the number of bits to use to
1130 determine the random offset to the 1013 determine the random offset to the base address of vma regions
1131 resulting from mmap allocations for 1014 resulting from mmap allocations for compatible applications This
1132 value will be bounded by the archit 1015 value will be bounded by the architecture's minimum and maximum
1133 supported values. 1016 supported values.
1134 1017
1135 This value can be changed after boo 1018 This value can be changed after boot using the
1136 /proc/sys/vm/mmap_rnd_compat_bits t 1019 /proc/sys/vm/mmap_rnd_compat_bits tunable
1137 1020
1138 config HAVE_ARCH_COMPAT_MMAP_BASES 1021 config HAVE_ARCH_COMPAT_MMAP_BASES
1139 bool 1022 bool
1140 help 1023 help
1141 This allows 64bit applications to i 1024 This allows 64bit applications to invoke 32-bit mmap() syscall
1142 and vice-versa 32-bit applications 1025 and vice-versa 32-bit applications to call 64-bit mmap().
1143 Required for applications doing dif 1026 Required for applications doing different bitness syscalls.
1144 1027
1145 config HAVE_PAGE_SIZE_4KB <<
1146 bool <<
1147 <<
1148 config HAVE_PAGE_SIZE_8KB <<
1149 bool <<
1150 <<
1151 config HAVE_PAGE_SIZE_16KB <<
1152 bool <<
1153 <<
1154 config HAVE_PAGE_SIZE_32KB <<
1155 bool <<
1156 <<
1157 config HAVE_PAGE_SIZE_64KB <<
1158 bool <<
1159 <<
1160 config HAVE_PAGE_SIZE_256KB <<
1161 bool <<
1162 <<
1163 choice <<
1164 prompt "MMU page size" <<
1165 <<
1166 config PAGE_SIZE_4KB <<
1167 bool "4KiB pages" <<
1168 depends on HAVE_PAGE_SIZE_4KB <<
1169 help <<
1170 This option select the standard 4Ki <<
1171 available option on many architectu <<
1172 minimize memory consumption and is <<
1173 memory systems. <<
1174 Some software that is written for x <<
1175 assumptions about the page size and <<
1176 <<
1177 config PAGE_SIZE_8KB <<
1178 bool "8KiB pages" <<
1179 depends on HAVE_PAGE_SIZE_8KB <<
1180 help <<
1181 This option is the only supported p <<
1182 processors, and can be slightly fas <<
1183 <<
1184 config PAGE_SIZE_16KB <<
1185 bool "16KiB pages" <<
1186 depends on HAVE_PAGE_SIZE_16KB <<
1187 help <<
1188 This option is usually a good compr <<
1189 consumption and performance for typ <<
1190 workloads, often saving a level of <<
1191 to 4KB pages as well as reducing TL <<
1192 per-page operations in the kernel a <<
1193 page cache. <<
1194 <<
1195 config PAGE_SIZE_32KB <<
1196 bool "32KiB pages" <<
1197 depends on HAVE_PAGE_SIZE_32KB <<
1198 help <<
1199 Using 32KiB page size will result i <<
1200 kernel at the price of higher memor <<
1201 16KiB pages. This option is availa <<
1202 Note that you will need a suitable <<
1203 support this. <<
1204 <<
1205 config PAGE_SIZE_64KB <<
1206 bool "64KiB pages" <<
1207 depends on HAVE_PAGE_SIZE_64KB <<
1208 help <<
1209 Using 64KiB page size will result i <<
1210 kernel at the price of much higher <<
1211 4KiB or 16KiB pages. <<
1212 This is not suitable for general-pu <<
1213 better performance may be worth the <<
1214 supercomputing or database applicat <<
1215 large in-memory data rather than sm <<
1216 <<
1217 config PAGE_SIZE_256KB <<
1218 bool "256KiB pages" <<
1219 depends on HAVE_PAGE_SIZE_256KB <<
1220 help <<
1221 256KiB pages have little practical <<
1222 memory usage. The kernel will only <<
1223 that have been compiled with '-zmax <<
1224 (the default is 64KiB or 4KiB on mo <<
1225 <<
1226 endchoice <<
1227 <<
1228 config PAGE_SIZE_LESS_THAN_64KB 1028 config PAGE_SIZE_LESS_THAN_64KB
1229 def_bool y 1029 def_bool y
>> 1030 depends on !ARM64_64K_PAGES
>> 1031 depends on !IA64_PAGE_SIZE_64KB
1230 depends on !PAGE_SIZE_64KB 1032 depends on !PAGE_SIZE_64KB
>> 1033 depends on !PARISC_PAGE_SIZE_64KB
1231 depends on PAGE_SIZE_LESS_THAN_256KB 1034 depends on PAGE_SIZE_LESS_THAN_256KB
1232 1035
1233 config PAGE_SIZE_LESS_THAN_256KB 1036 config PAGE_SIZE_LESS_THAN_256KB
1234 def_bool y 1037 def_bool y
1235 depends on !PAGE_SIZE_256KB 1038 depends on !PAGE_SIZE_256KB
1236 1039
1237 config PAGE_SHIFT <<
1238 int <<
1239 default 12 if PAGE_SIZE_4KB <<
1240 default 13 if PAGE_SIZE_8KB <<
1241 default 14 if PAGE_SIZE_16KB <<
1242 default 15 if PAGE_SIZE_32KB <<
1243 default 16 if PAGE_SIZE_64KB <<
1244 default 18 if PAGE_SIZE_256KB <<
1245 <<
1246 # This allows to use a set of generic functio 1040 # This allows to use a set of generic functions to determine mmap base
1247 # address by giving priority to top-down sche 1041 # address by giving priority to top-down scheme only if the process
1248 # is not in legacy mode (compat task, unlimit 1042 # is not in legacy mode (compat task, unlimited stack size or
1249 # sysctl_legacy_va_layout). 1043 # sysctl_legacy_va_layout).
1250 # Architecture that selects this option can p 1044 # Architecture that selects this option can provide its own version of:
1251 # - STACK_RND_MASK 1045 # - STACK_RND_MASK
1252 config ARCH_WANT_DEFAULT_TOPDOWN_MMAP_LAYOUT 1046 config ARCH_WANT_DEFAULT_TOPDOWN_MMAP_LAYOUT
1253 bool 1047 bool
1254 depends on MMU 1048 depends on MMU
1255 select ARCH_HAS_ELF_RANDOMIZE 1049 select ARCH_HAS_ELF_RANDOMIZE
1256 1050
1257 config HAVE_OBJTOOL 1051 config HAVE_OBJTOOL
1258 bool 1052 bool
1259 1053
1260 config HAVE_JUMP_LABEL_HACK 1054 config HAVE_JUMP_LABEL_HACK
1261 bool 1055 bool
1262 1056
1263 config HAVE_NOINSTR_HACK 1057 config HAVE_NOINSTR_HACK
1264 bool 1058 bool
1265 1059
1266 config HAVE_NOINSTR_VALIDATION 1060 config HAVE_NOINSTR_VALIDATION
1267 bool 1061 bool
1268 1062
1269 config HAVE_UACCESS_VALIDATION 1063 config HAVE_UACCESS_VALIDATION
1270 bool 1064 bool
1271 select OBJTOOL 1065 select OBJTOOL
1272 1066
1273 config HAVE_STACK_VALIDATION 1067 config HAVE_STACK_VALIDATION
1274 bool 1068 bool
1275 help 1069 help
1276 Architecture supports objtool compi 1070 Architecture supports objtool compile-time frame pointer rule
1277 validation. 1071 validation.
1278 1072
1279 config HAVE_RELIABLE_STACKTRACE 1073 config HAVE_RELIABLE_STACKTRACE
1280 bool 1074 bool
1281 help 1075 help
1282 Architecture has either save_stack_ 1076 Architecture has either save_stack_trace_tsk_reliable() or
1283 arch_stack_walk_reliable() function 1077 arch_stack_walk_reliable() function which only returns a stack trace
1284 if it can guarantee the trace is re 1078 if it can guarantee the trace is reliable.
1285 1079
1286 config HAVE_ARCH_HASH 1080 config HAVE_ARCH_HASH
1287 bool 1081 bool
1288 default n 1082 default n
1289 help 1083 help
1290 If this is set, the architecture pr 1084 If this is set, the architecture provides an <asm/hash.h>
1291 file which provides platform-specif 1085 file which provides platform-specific implementations of some
1292 functions in <linux/hash.h> or fs/n 1086 functions in <linux/hash.h> or fs/namei.c.
1293 1087
1294 config HAVE_ARCH_NVRAM_OPS 1088 config HAVE_ARCH_NVRAM_OPS
1295 bool 1089 bool
1296 1090
1297 config ISA_BUS_API 1091 config ISA_BUS_API
1298 def_bool ISA 1092 def_bool ISA
1299 1093
1300 # 1094 #
1301 # ABI hall of shame 1095 # ABI hall of shame
1302 # 1096 #
1303 config CLONE_BACKWARDS 1097 config CLONE_BACKWARDS
1304 bool 1098 bool
1305 help 1099 help
1306 Architecture has tls passed as the 1100 Architecture has tls passed as the 4th argument of clone(2),
1307 not the 5th one. 1101 not the 5th one.
1308 1102
1309 config CLONE_BACKWARDS2 1103 config CLONE_BACKWARDS2
1310 bool 1104 bool
1311 help 1105 help
1312 Architecture has the first two argu 1106 Architecture has the first two arguments of clone(2) swapped.
1313 1107
1314 config CLONE_BACKWARDS3 1108 config CLONE_BACKWARDS3
1315 bool 1109 bool
1316 help 1110 help
1317 Architecture has tls passed as the 1111 Architecture has tls passed as the 3rd argument of clone(2),
1318 not the 5th one. 1112 not the 5th one.
1319 1113
1320 config ODD_RT_SIGACTION 1114 config ODD_RT_SIGACTION
1321 bool 1115 bool
1322 help 1116 help
1323 Architecture has unusual rt_sigacti 1117 Architecture has unusual rt_sigaction(2) arguments
1324 1118
1325 config OLD_SIGSUSPEND 1119 config OLD_SIGSUSPEND
1326 bool 1120 bool
1327 help 1121 help
1328 Architecture has old sigsuspend(2) 1122 Architecture has old sigsuspend(2) syscall, of one-argument variety
1329 1123
1330 config OLD_SIGSUSPEND3 1124 config OLD_SIGSUSPEND3
1331 bool 1125 bool
1332 help 1126 help
1333 Even weirder antique ABI - three-ar 1127 Even weirder antique ABI - three-argument sigsuspend(2)
1334 1128
1335 config OLD_SIGACTION 1129 config OLD_SIGACTION
1336 bool 1130 bool
1337 help 1131 help
1338 Architecture has old sigaction(2) s 1132 Architecture has old sigaction(2) syscall. Nope, not the same
1339 as OLD_SIGSUSPEND | OLD_SIGSUSPEND3 1133 as OLD_SIGSUSPEND | OLD_SIGSUSPEND3 - alpha has sigsuspend(2),
1340 but fairly different variant of sig 1134 but fairly different variant of sigaction(2), thanks to OSF/1
1341 compatibility... 1135 compatibility...
1342 1136
1343 config COMPAT_OLD_SIGACTION 1137 config COMPAT_OLD_SIGACTION
1344 bool 1138 bool
1345 1139
1346 config COMPAT_32BIT_TIME 1140 config COMPAT_32BIT_TIME
1347 bool "Provide system calls for 32-bit 1141 bool "Provide system calls for 32-bit time_t"
1348 default !64BIT || COMPAT 1142 default !64BIT || COMPAT
1349 help 1143 help
1350 This enables 32 bit time_t support 1144 This enables 32 bit time_t support in addition to 64 bit time_t support.
1351 This is relevant on all 32-bit arch 1145 This is relevant on all 32-bit architectures, and 64-bit architectures
1352 as part of compat syscall handling. 1146 as part of compat syscall handling.
1353 1147
1354 config ARCH_NO_PREEMPT 1148 config ARCH_NO_PREEMPT
1355 bool 1149 bool
1356 1150
>> 1151 config ARCH_EPHEMERAL_INODES
>> 1152 def_bool n
>> 1153 help
>> 1154 An arch should select this symbol if it doesn't keep track of inode
>> 1155 instances on its own, but instead relies on something else (e.g. the
>> 1156 host kernel for an UML kernel).
>> 1157
1357 config ARCH_SUPPORTS_RT 1158 config ARCH_SUPPORTS_RT
1358 bool 1159 bool
1359 1160
1360 config CPU_NO_EFFICIENT_FFS 1161 config CPU_NO_EFFICIENT_FFS
1361 def_bool n 1162 def_bool n
1362 1163
1363 config HAVE_ARCH_VMAP_STACK 1164 config HAVE_ARCH_VMAP_STACK
1364 def_bool n 1165 def_bool n
1365 help 1166 help
1366 An arch should select this symbol i 1167 An arch should select this symbol if it can support kernel stacks
1367 in vmalloc space. This means: 1168 in vmalloc space. This means:
1368 1169
1369 - vmalloc space must be large enoug 1170 - vmalloc space must be large enough to hold many kernel stacks.
1370 This may rule out many 32-bit arc 1171 This may rule out many 32-bit architectures.
1371 1172
1372 - Stacks in vmalloc space need to w 1173 - Stacks in vmalloc space need to work reliably. For example, if
1373 vmap page tables are created on d 1174 vmap page tables are created on demand, either this mechanism
1374 needs to work while the stack poi 1175 needs to work while the stack points to a virtual address with
1375 unpopulated page tables or arch c 1176 unpopulated page tables or arch code (switch_to() and switch_mm(),
1376 most likely) needs to ensure that 1177 most likely) needs to ensure that the stack's page table entries
1377 are populated before running on a 1178 are populated before running on a possibly unpopulated stack.
1378 1179
1379 - If the stack overflows into a gua 1180 - If the stack overflows into a guard page, something reasonable
1380 should happen. The definition of 1181 should happen. The definition of "reasonable" is flexible, but
1381 instantly rebooting without loggi 1182 instantly rebooting without logging anything would be unfriendly.
1382 1183
1383 config VMAP_STACK 1184 config VMAP_STACK
1384 default y 1185 default y
1385 bool "Use a virtually-mapped stack" 1186 bool "Use a virtually-mapped stack"
1386 depends on HAVE_ARCH_VMAP_STACK 1187 depends on HAVE_ARCH_VMAP_STACK
1387 depends on !KASAN || KASAN_HW_TAGS || 1188 depends on !KASAN || KASAN_HW_TAGS || KASAN_VMALLOC
1388 help 1189 help
1389 Enable this if you want the use vir 1190 Enable this if you want the use virtually-mapped kernel stacks
1390 with guard pages. This causes kern 1191 with guard pages. This causes kernel stack overflows to be
1391 caught immediately rather than caus 1192 caught immediately rather than causing difficult-to-diagnose
1392 corruption. 1193 corruption.
1393 1194
1394 To use this with software KASAN mod 1195 To use this with software KASAN modes, the architecture must support
1395 backing virtual mappings with real 1196 backing virtual mappings with real shadow memory, and KASAN_VMALLOC
1396 must be enabled. 1197 must be enabled.
1397 1198
1398 config HAVE_ARCH_RANDOMIZE_KSTACK_OFFSET 1199 config HAVE_ARCH_RANDOMIZE_KSTACK_OFFSET
1399 def_bool n 1200 def_bool n
1400 help 1201 help
1401 An arch should select this symbol i 1202 An arch should select this symbol if it can support kernel stack
1402 offset randomization with calls to 1203 offset randomization with calls to add_random_kstack_offset()
1403 during syscall entry and choose_ran 1204 during syscall entry and choose_random_kstack_offset() during
1404 syscall exit. Careful removal of -f 1205 syscall exit. Careful removal of -fstack-protector-strong and
1405 -fstack-protector should also be ap 1206 -fstack-protector should also be applied to the entry code and
1406 closely examined, as the artificial 1207 closely examined, as the artificial stack bump looks like an array
1407 to the compiler, so it will attempt 1208 to the compiler, so it will attempt to add canary checks regardless
1408 of the static branch state. 1209 of the static branch state.
1409 1210
1410 config RANDOMIZE_KSTACK_OFFSET 1211 config RANDOMIZE_KSTACK_OFFSET
1411 bool "Support for randomizing kernel 1212 bool "Support for randomizing kernel stack offset on syscall entry" if EXPERT
1412 default y 1213 default y
1413 depends on HAVE_ARCH_RANDOMIZE_KSTACK 1214 depends on HAVE_ARCH_RANDOMIZE_KSTACK_OFFSET
1414 depends on INIT_STACK_NONE || !CC_IS_ 1215 depends on INIT_STACK_NONE || !CC_IS_CLANG || CLANG_VERSION >= 140000
1415 help 1216 help
1416 The kernel stack offset can be rand 1217 The kernel stack offset can be randomized (after pt_regs) by
1417 roughly 5 bits of entropy, frustrat 1218 roughly 5 bits of entropy, frustrating memory corruption
1418 attacks that depend on stack addres 1219 attacks that depend on stack address determinism or
1419 cross-syscall address exposures. 1220 cross-syscall address exposures.
1420 1221
1421 The feature is controlled via the " 1222 The feature is controlled via the "randomize_kstack_offset=on/off"
1422 kernel boot param, and if turned of 1223 kernel boot param, and if turned off has zero overhead due to its use
1423 of static branches (see JUMP_LABEL) 1224 of static branches (see JUMP_LABEL).
1424 1225
1425 If unsure, say Y. 1226 If unsure, say Y.
1426 1227
1427 config RANDOMIZE_KSTACK_OFFSET_DEFAULT 1228 config RANDOMIZE_KSTACK_OFFSET_DEFAULT
1428 bool "Default state of kernel stack o 1229 bool "Default state of kernel stack offset randomization"
1429 depends on RANDOMIZE_KSTACK_OFFSET 1230 depends on RANDOMIZE_KSTACK_OFFSET
1430 help 1231 help
1431 Kernel stack offset randomization i 1232 Kernel stack offset randomization is controlled by kernel boot param
1432 "randomize_kstack_offset=on/off", a 1233 "randomize_kstack_offset=on/off", and this config chooses the default
1433 boot state. 1234 boot state.
1434 1235
1435 config ARCH_OPTIONAL_KERNEL_RWX 1236 config ARCH_OPTIONAL_KERNEL_RWX
1436 def_bool n 1237 def_bool n
1437 1238
1438 config ARCH_OPTIONAL_KERNEL_RWX_DEFAULT 1239 config ARCH_OPTIONAL_KERNEL_RWX_DEFAULT
1439 def_bool n 1240 def_bool n
1440 1241
1441 config ARCH_HAS_STRICT_KERNEL_RWX 1242 config ARCH_HAS_STRICT_KERNEL_RWX
1442 def_bool n 1243 def_bool n
1443 1244
1444 config STRICT_KERNEL_RWX 1245 config STRICT_KERNEL_RWX
1445 bool "Make kernel text and rodata rea 1246 bool "Make kernel text and rodata read-only" if ARCH_OPTIONAL_KERNEL_RWX
1446 depends on ARCH_HAS_STRICT_KERNEL_RWX 1247 depends on ARCH_HAS_STRICT_KERNEL_RWX
1447 default !ARCH_OPTIONAL_KERNEL_RWX || 1248 default !ARCH_OPTIONAL_KERNEL_RWX || ARCH_OPTIONAL_KERNEL_RWX_DEFAULT
1448 help 1249 help
1449 If this is set, kernel text and rod 1250 If this is set, kernel text and rodata memory will be made read-only,
1450 and non-text memory will be made no 1251 and non-text memory will be made non-executable. This provides
1451 protection against certain security 1252 protection against certain security exploits (e.g. executing the heap
1452 or modifying text) 1253 or modifying text)
1453 1254
1454 These features are considered stand 1255 These features are considered standard security practice these days.
1455 You should say Y here in almost all 1256 You should say Y here in almost all cases.
1456 1257
1457 config ARCH_HAS_STRICT_MODULE_RWX 1258 config ARCH_HAS_STRICT_MODULE_RWX
1458 def_bool n 1259 def_bool n
1459 1260
1460 config STRICT_MODULE_RWX 1261 config STRICT_MODULE_RWX
1461 bool "Set loadable kernel module data 1262 bool "Set loadable kernel module data as NX and text as RO" if ARCH_OPTIONAL_KERNEL_RWX
1462 depends on ARCH_HAS_STRICT_MODULE_RWX 1263 depends on ARCH_HAS_STRICT_MODULE_RWX && MODULES
1463 default !ARCH_OPTIONAL_KERNEL_RWX || 1264 default !ARCH_OPTIONAL_KERNEL_RWX || ARCH_OPTIONAL_KERNEL_RWX_DEFAULT
1464 help 1265 help
1465 If this is set, module text and rod 1266 If this is set, module text and rodata memory will be made read-only,
1466 and non-text memory will be made no 1267 and non-text memory will be made non-executable. This provides
1467 protection against certain security 1268 protection against certain security exploits (e.g. writing to text)
1468 1269
1469 # select if the architecture provides an asm/ 1270 # select if the architecture provides an asm/dma-direct.h header
1470 config ARCH_HAS_PHYS_TO_DMA 1271 config ARCH_HAS_PHYS_TO_DMA
1471 bool 1272 bool
1472 1273
1473 config HAVE_ARCH_COMPILER_H 1274 config HAVE_ARCH_COMPILER_H
1474 bool 1275 bool
1475 help 1276 help
1476 An architecture can select this if 1277 An architecture can select this if it provides an
1477 asm/compiler.h header that should b 1278 asm/compiler.h header that should be included after
1478 linux/compiler-*.h in order to over 1279 linux/compiler-*.h in order to override macro definitions that those
1479 headers generally provide. 1280 headers generally provide.
1480 1281
1481 config HAVE_ARCH_PREL32_RELOCATIONS 1282 config HAVE_ARCH_PREL32_RELOCATIONS
1482 bool 1283 bool
1483 help 1284 help
1484 May be selected by an architecture 1285 May be selected by an architecture if it supports place-relative
1485 32-bit relocations, both in the too 1286 32-bit relocations, both in the toolchain and in the module loader,
1486 in which case relative references c 1287 in which case relative references can be used in special sections
1487 for PCI fixup, initcalls etc which 1288 for PCI fixup, initcalls etc which are only half the size on 64 bit
1488 architectures, and don't require ru 1289 architectures, and don't require runtime relocation on relocatable
1489 kernels. 1290 kernels.
1490 1291
1491 config ARCH_USE_MEMREMAP_PROT 1292 config ARCH_USE_MEMREMAP_PROT
1492 bool 1293 bool
1493 1294
1494 config LOCK_EVENT_COUNTS 1295 config LOCK_EVENT_COUNTS
1495 bool "Locking event counts collection 1296 bool "Locking event counts collection"
1496 depends on DEBUG_FS 1297 depends on DEBUG_FS
1497 help 1298 help
1498 Enable light-weight counting of var 1299 Enable light-weight counting of various locking related events
1499 in the system with minimal performa 1300 in the system with minimal performance impact. This reduces
1500 the chance of application behavior 1301 the chance of application behavior change because of timing
1501 differences. The counts are reporte 1302 differences. The counts are reported via debugfs.
1502 1303
1503 # Select if the architecture has support for 1304 # Select if the architecture has support for applying RELR relocations.
1504 config ARCH_HAS_RELR 1305 config ARCH_HAS_RELR
1505 bool 1306 bool
1506 1307
1507 config RELR 1308 config RELR
1508 bool "Use RELR relocation packing" 1309 bool "Use RELR relocation packing"
1509 depends on ARCH_HAS_RELR && TOOLS_SUP 1310 depends on ARCH_HAS_RELR && TOOLS_SUPPORT_RELR
1510 default y 1311 default y
1511 help 1312 help
1512 Store the kernel's dynamic relocati 1313 Store the kernel's dynamic relocations in the RELR relocation packing
1513 format. Requires a compatible linke 1314 format. Requires a compatible linker (LLD supports this feature), as
1514 well as compatible NM and OBJCOPY u 1315 well as compatible NM and OBJCOPY utilities (llvm-nm and llvm-objcopy
1515 are compatible). 1316 are compatible).
1516 1317
1517 config ARCH_HAS_MEM_ENCRYPT 1318 config ARCH_HAS_MEM_ENCRYPT
1518 bool 1319 bool
1519 1320
1520 config ARCH_HAS_CC_PLATFORM 1321 config ARCH_HAS_CC_PLATFORM
1521 bool 1322 bool
1522 1323
1523 config HAVE_SPARSE_SYSCALL_NR 1324 config HAVE_SPARSE_SYSCALL_NR
1524 bool !! 1325 bool
1525 help !! 1326 help
1526 An architecture should select this !! 1327 An architecture should select this if its syscall numbering is sparse
1527 to save space. For example, MIPS ar 1328 to save space. For example, MIPS architecture has a syscall array with
1528 entries at 4000, 5000 and 6000 loca 1329 entries at 4000, 5000 and 6000 locations. This option turns on syscall
1529 related optimizations for a given a 1330 related optimizations for a given architecture.
1530 1331
1531 config ARCH_HAS_VDSO_DATA 1332 config ARCH_HAS_VDSO_DATA
1532 bool 1333 bool
1533 1334
1534 config HAVE_STATIC_CALL 1335 config HAVE_STATIC_CALL
1535 bool 1336 bool
1536 1337
1537 config HAVE_STATIC_CALL_INLINE 1338 config HAVE_STATIC_CALL_INLINE
1538 bool 1339 bool
1539 depends on HAVE_STATIC_CALL 1340 depends on HAVE_STATIC_CALL
1540 select OBJTOOL 1341 select OBJTOOL
1541 1342
1542 config HAVE_PREEMPT_DYNAMIC 1343 config HAVE_PREEMPT_DYNAMIC
1543 bool 1344 bool
1544 1345
1545 config HAVE_PREEMPT_DYNAMIC_CALL 1346 config HAVE_PREEMPT_DYNAMIC_CALL
1546 bool 1347 bool
1547 depends on HAVE_STATIC_CALL 1348 depends on HAVE_STATIC_CALL
1548 select HAVE_PREEMPT_DYNAMIC 1349 select HAVE_PREEMPT_DYNAMIC
1549 help 1350 help
1550 An architecture should select this !! 1351 An architecture should select this if it can handle the preemption
1551 model being selected at boot time u !! 1352 model being selected at boot time using static calls.
1552 1353
1553 Where an architecture selects HAVE_ !! 1354 Where an architecture selects HAVE_STATIC_CALL_INLINE, any call to a
1554 preemption function will be patched !! 1355 preemption function will be patched directly.
1555 1356
1556 Where an architecture does not sele !! 1357 Where an architecture does not select HAVE_STATIC_CALL_INLINE, any
1557 call to a preemption function will !! 1358 call to a preemption function will go through a trampoline, and the
1558 trampoline will be patched. !! 1359 trampoline will be patched.
1559 1360
1560 It is strongly advised to support i !! 1361 It is strongly advised to support inline static call to avoid any
1561 overhead. !! 1362 overhead.
1562 1363
1563 config HAVE_PREEMPT_DYNAMIC_KEY 1364 config HAVE_PREEMPT_DYNAMIC_KEY
1564 bool 1365 bool
1565 depends on HAVE_ARCH_JUMP_LABEL 1366 depends on HAVE_ARCH_JUMP_LABEL
1566 select HAVE_PREEMPT_DYNAMIC 1367 select HAVE_PREEMPT_DYNAMIC
1567 help 1368 help
1568 An architecture should select this !! 1369 An architecture should select this if it can handle the preemption
1569 model being selected at boot time u !! 1370 model being selected at boot time using static keys.
1570 1371
1571 Each preemption function will be gi !! 1372 Each preemption function will be given an early return based on a
1572 static key. This should have slight !! 1373 static key. This should have slightly lower overhead than non-inline
1573 static calls, as this effectively i !! 1374 static calls, as this effectively inlines each trampoline into the
1574 start of its callee. This may avoid !! 1375 start of its callee. This may avoid redundant work, and may
1575 integrate better with CFI schemes. !! 1376 integrate better with CFI schemes.
1576 1377
1577 This will have greater overhead tha !! 1378 This will have greater overhead than using inline static calls as
1578 the call to the preemption function !! 1379 the call to the preemption function cannot be entirely elided.
1579 1380
1580 config ARCH_WANT_LD_ORPHAN_WARN 1381 config ARCH_WANT_LD_ORPHAN_WARN
1581 bool 1382 bool
1582 help 1383 help
1583 An arch should select this symbol o 1384 An arch should select this symbol once all linker sections are explicitly
1584 included, size-asserted, or discard 1385 included, size-asserted, or discarded in the linker scripts. This is
1585 important because we never want exp 1386 important because we never want expected sections to be placed heuristically
1586 by the linker, since the locations 1387 by the linker, since the locations of such sections can change between linker
1587 versions. 1388 versions.
1588 1389
1589 config HAVE_ARCH_PFN_VALID 1390 config HAVE_ARCH_PFN_VALID
1590 bool 1391 bool
1591 1392
1592 config ARCH_SUPPORTS_DEBUG_PAGEALLOC 1393 config ARCH_SUPPORTS_DEBUG_PAGEALLOC
1593 bool 1394 bool
1594 1395
1595 config ARCH_SUPPORTS_PAGE_TABLE_CHECK 1396 config ARCH_SUPPORTS_PAGE_TABLE_CHECK
1596 bool 1397 bool
1597 1398
1598 config ARCH_SPLIT_ARG64 1399 config ARCH_SPLIT_ARG64
1599 bool 1400 bool
1600 help 1401 help
1601 If a 32-bit architecture requires 6 !! 1402 If a 32-bit architecture requires 64-bit arguments to be split into
1602 pairs of 32-bit arguments, select t !! 1403 pairs of 32-bit arguments, select this option.
1603 1404
1604 config ARCH_HAS_ELFCORE_COMPAT 1405 config ARCH_HAS_ELFCORE_COMPAT
1605 bool 1406 bool
1606 1407
1607 config ARCH_HAS_PARANOID_L1D_FLUSH 1408 config ARCH_HAS_PARANOID_L1D_FLUSH
1608 bool 1409 bool
1609 1410
1610 config ARCH_HAVE_TRACE_MMIO_ACCESS 1411 config ARCH_HAVE_TRACE_MMIO_ACCESS
1611 bool 1412 bool
1612 1413
1613 config DYNAMIC_SIGFRAME 1414 config DYNAMIC_SIGFRAME
1614 bool 1415 bool
1615 1416
1616 # Select, if arch has a named attribute group 1417 # Select, if arch has a named attribute group bound to NUMA device nodes.
1617 config HAVE_ARCH_NODE_DEV_GROUP 1418 config HAVE_ARCH_NODE_DEV_GROUP
1618 bool 1419 bool
1619 1420
1620 config ARCH_HAS_HW_PTE_YOUNG <<
1621 bool <<
1622 help <<
1623 Architectures that select this opti <<
1624 accessed bit in PTE entries when us <<
1625 translations. Architectures that re <<
1626 this option and override arch_has_h <<
1627 <<
1628 config ARCH_HAS_NONLEAF_PMD_YOUNG <<
1629 bool <<
1630 help <<
1631 Architectures that select this opti <<
1632 accessed bit in non-leaf PMD entrie <<
1633 address translations. Page table wa <<
1634 may use this capability to reduce t <<
1635 <<
1636 config ARCH_HAS_KERNEL_FPU_SUPPORT <<
1637 bool <<
1638 help <<
1639 Architectures that select this opti <<
1640 the kernel, as described in Documen <<
1641 <<
1642 source "kernel/gcov/Kconfig" 1421 source "kernel/gcov/Kconfig"
1643 1422
1644 source "scripts/gcc-plugins/Kconfig" 1423 source "scripts/gcc-plugins/Kconfig"
1645 <<
1646 config FUNCTION_ALIGNMENT_4B <<
1647 bool <<
1648 <<
1649 config FUNCTION_ALIGNMENT_8B <<
1650 bool <<
1651 <<
1652 config FUNCTION_ALIGNMENT_16B <<
1653 bool <<
1654 <<
1655 config FUNCTION_ALIGNMENT_32B <<
1656 bool <<
1657 <<
1658 config FUNCTION_ALIGNMENT_64B <<
1659 bool <<
1660 <<
1661 config FUNCTION_ALIGNMENT <<
1662 int <<
1663 default 64 if FUNCTION_ALIGNMENT_64B <<
1664 default 32 if FUNCTION_ALIGNMENT_32B <<
1665 default 16 if FUNCTION_ALIGNMENT_16B <<
1666 default 8 if FUNCTION_ALIGNMENT_8B <<
1667 default 4 if FUNCTION_ALIGNMENT_4B <<
1668 default 0 <<
1669 <<
1670 config CC_HAS_MIN_FUNCTION_ALIGNMENT <<
1671 # Detect availability of the GCC opti <<
1672 # guarantees minimal alignment for al <<
1673 # -falign-functions which the compile <<
1674 def_bool $(cc-option, -fmin-function- <<
1675 <<
1676 config CC_HAS_SANE_FUNCTION_ALIGNMENT <<
1677 # Set if the guaranteed alignment wit <<
1678 # available or extra care is required <<
1679 # strict alignment always, even with <<
1680 def_bool CC_HAS_MIN_FUNCTION_ALIGNMEN <<
1681 <<
1682 config ARCH_NEED_CMPXCHG_1_EMU <<
1683 bool <<
1684 1424
1685 endmenu 1425 endmenu
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