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