1 # SPDX-License-Identifier: GPL-2.0 1 # SPDX-License-Identifier: GPL-2.0
2 # 2 #
3 # General architecture dependent options 3 # General architecture dependent options
4 # 4 #
5 5
6 # 6 #
7 # Note: arch/$(SRCARCH)/Kconfig needs to be in 7 # Note: arch/$(SRCARCH)/Kconfig needs to be included first so that it can
8 # override the default values in this file. 8 # override the default values in this file.
9 # 9 #
10 source "arch/$(SRCARCH)/Kconfig" 10 source "arch/$(SRCARCH)/Kconfig"
11 11
12 config ARCH_CONFIGURES_CPU_MITIGATIONS <<
13 bool <<
14 <<
15 if !ARCH_CONFIGURES_CPU_MITIGATIONS <<
16 config CPU_MITIGATIONS <<
17 def_bool y <<
18 endif <<
19 <<
20 # <<
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" 12 menu "General architecture-dependent options"
30 13
31 config ARCH_HAS_SUBPAGE_FAULTS !! 14 config CRASH_CORE
32 bool 15 bool
33 help <<
34 Select if the architecture can check <<
35 granularity (e.g. arm64 MTE). The pr <<
36 must be implemented. <<
37 16
38 config HOTPLUG_SMT !! 17 config KEXEC_CORE
>> 18 select CRASH_CORE
39 bool 19 bool
40 20
41 config SMT_NUM_THREADS_DYNAMIC !! 21 config KEXEC_ELF
42 bool 22 bool
43 23
44 # Selected by HOTPLUG_CORE_SYNC_DEAD or HOTPLU !! 24 config HAVE_IMA_KEXEC
45 config HOTPLUG_CORE_SYNC <<
46 bool 25 bool
47 26
48 # Basic CPU dead synchronization selected by a !! 27 config SET_FS
49 config HOTPLUG_CORE_SYNC_DEAD <<
50 bool 28 bool
51 select HOTPLUG_CORE_SYNC <<
52 29
53 # Full CPU synchronization with alive state se !! 30 config HOTPLUG_SMT
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 31 bool
65 select HOTPLUG_SPLIT_STARTUP <<
66 32
67 config GENERIC_ENTRY 33 config GENERIC_ENTRY
68 bool !! 34 bool
69 35
70 config KPROBES 36 config KPROBES
71 bool "Kprobes" 37 bool "Kprobes"
>> 38 depends on MODULES
72 depends on HAVE_KPROBES 39 depends on HAVE_KPROBES
73 select KALLSYMS 40 select KALLSYMS
74 select EXECMEM <<
75 select NEED_TASKS_RCU <<
76 help 41 help
77 Kprobes allows you to trap at almost 42 Kprobes allows you to trap at almost any kernel address and
78 execute a callback function. regist 43 execute a callback function. register_kprobe() establishes
79 a probepoint and specifies the callb 44 a probepoint and specifies the callback. Kprobes is useful
80 for kernel debugging, non-intrusive 45 for kernel debugging, non-intrusive instrumentation and testing.
81 If in doubt, say "N". 46 If in doubt, say "N".
82 47
83 config JUMP_LABEL 48 config JUMP_LABEL
84 bool "Optimize very unlikely/likely br 49 bool "Optimize very unlikely/likely branches"
85 depends on HAVE_ARCH_JUMP_LABEL 50 depends on HAVE_ARCH_JUMP_LABEL
86 select OBJTOOL if HAVE_JUMP_LABEL_HACK !! 51 depends on CC_HAS_ASM_GOTO
87 help 52 help
88 This option enables a transparent br !! 53 This option enables a transparent branch optimization that
89 makes certain almost-always-true or !! 54 makes certain almost-always-true or almost-always-false branch
90 conditions even cheaper to execute w !! 55 conditions even cheaper to execute within the kernel.
91 !! 56
92 Certain performance-sensitive kernel !! 57 Certain performance-sensitive kernel code, such as trace points,
93 scheduler functionality, networking !! 58 scheduler functionality, networking code and KVM have such
94 branches and include support for thi !! 59 branches and include support for this optimization technique.
95 !! 60
96 If it is detected that the compiler !! 61 If it is detected that the compiler has support for "asm goto",
97 the kernel will compile such branche !! 62 the kernel will compile such branches with just a nop
98 instruction. When the condition flag !! 63 instruction. When the condition flag is toggled to true, the
99 nop will be converted to a jump inst !! 64 nop will be converted to a jump instruction to execute the
100 conditional block of instructions. !! 65 conditional block of instructions.
101 !! 66
102 This technique lowers overhead and s !! 67 This technique lowers overhead and stress on the branch prediction
103 of the processor and generally makes !! 68 of the processor and generally makes the kernel faster. The update
104 of the condition is slower, but thos !! 69 of the condition is slower, but those are always very rare.
105 70
106 ( On 32-bit x86, the necessary optio !! 71 ( On 32-bit x86, the necessary options added to the compiler
107 flags may increase the size of the !! 72 flags may increase the size of the kernel slightly. )
108 73
109 config STATIC_KEYS_SELFTEST 74 config STATIC_KEYS_SELFTEST
110 bool "Static key selftest" 75 bool "Static key selftest"
111 depends on JUMP_LABEL 76 depends on JUMP_LABEL
112 help 77 help
113 Boot time self-test of the branch pa 78 Boot time self-test of the branch patching code.
114 79
115 config STATIC_CALL_SELFTEST 80 config STATIC_CALL_SELFTEST
116 bool "Static call selftest" 81 bool "Static call selftest"
117 depends on HAVE_STATIC_CALL 82 depends on HAVE_STATIC_CALL
118 help 83 help
119 Boot time self-test of the call patc 84 Boot time self-test of the call patching code.
120 85
121 config OPTPROBES 86 config OPTPROBES
122 def_bool y 87 def_bool y
123 depends on KPROBES && HAVE_OPTPROBES 88 depends on KPROBES && HAVE_OPTPROBES
124 select NEED_TASKS_RCU !! 89 select TASKS_RCU if PREEMPTION
125 90
126 config KPROBES_ON_FTRACE 91 config KPROBES_ON_FTRACE
127 def_bool y 92 def_bool y
128 depends on KPROBES && HAVE_KPROBES_ON_ 93 depends on KPROBES && HAVE_KPROBES_ON_FTRACE
129 depends on DYNAMIC_FTRACE_WITH_REGS 94 depends on DYNAMIC_FTRACE_WITH_REGS
130 help 95 help
131 If function tracer is enabled and th !! 96 If function tracer is enabled and the arch supports full
132 passing of pt_regs to function traci !! 97 passing of pt_regs to function tracing, then kprobes can
133 optimize on top of function tracing. !! 98 optimize on top of function tracing.
134 99
135 config UPROBES 100 config UPROBES
136 def_bool n 101 def_bool n
137 depends on ARCH_SUPPORTS_UPROBES 102 depends on ARCH_SUPPORTS_UPROBES
138 help 103 help
139 Uprobes is the user-space counterpar 104 Uprobes is the user-space counterpart to kprobes: they
140 enable instrumentation applications 105 enable instrumentation applications (such as 'perf probe')
141 to establish unintrusive probes in u 106 to establish unintrusive probes in user-space binaries and
142 libraries, by executing handler func 107 libraries, by executing handler functions when the probes
143 are hit by user-space applications. 108 are hit by user-space applications.
144 109
145 ( These probes come in the form of s 110 ( These probes come in the form of single-byte breakpoints,
146 managed by the kernel and kept tra 111 managed by the kernel and kept transparent to the probed
147 application. ) 112 application. )
148 113
149 config HAVE_64BIT_ALIGNED_ACCESS 114 config HAVE_64BIT_ALIGNED_ACCESS
150 def_bool 64BIT && !HAVE_EFFICIENT_UNAL 115 def_bool 64BIT && !HAVE_EFFICIENT_UNALIGNED_ACCESS
151 help 116 help
152 Some architectures require 64 bit ac 117 Some architectures require 64 bit accesses to be 64 bit
153 aligned, which also requires structs 118 aligned, which also requires structs containing 64 bit values
154 to be 64 bit aligned too. This inclu 119 to be 64 bit aligned too. This includes some 32 bit
155 architectures which can do 64 bit ac 120 architectures which can do 64 bit accesses, as well as 64 bit
156 architectures without unaligned acce 121 architectures without unaligned access.
157 122
158 This symbol should be selected by an 123 This symbol should be selected by an architecture if 64 bit
159 accesses are required to be 64 bit a 124 accesses are required to be 64 bit aligned in this way even
160 though it is not a 64 bit architectu 125 though it is not a 64 bit architecture.
161 126
162 See Documentation/core-api/unaligned 127 See Documentation/core-api/unaligned-memory-access.rst for
163 more information on the topic of una 128 more information on the topic of unaligned memory accesses.
164 129
165 config HAVE_EFFICIENT_UNALIGNED_ACCESS 130 config HAVE_EFFICIENT_UNALIGNED_ACCESS
166 bool 131 bool
167 help 132 help
168 Some architectures are unable to per 133 Some architectures are unable to perform unaligned accesses
169 without the use of get_unaligned/put 134 without the use of get_unaligned/put_unaligned. Others are
170 unable to perform such accesses effi 135 unable to perform such accesses efficiently (e.g. trap on
171 unaligned access and require fixing 136 unaligned access and require fixing it up in the exception
172 handler.) 137 handler.)
173 138
174 This symbol should be selected by an 139 This symbol should be selected by an architecture if it can
175 perform unaligned accesses efficient 140 perform unaligned accesses efficiently to allow different
176 code paths to be selected for these 141 code paths to be selected for these cases. Some network
177 drivers, for example, could opt to n 142 drivers, for example, could opt to not fix up alignment
178 problems with received packets if do 143 problems with received packets if doing so would not help
179 much. 144 much.
180 145
181 See Documentation/core-api/unaligned 146 See Documentation/core-api/unaligned-memory-access.rst for more
182 information on the topic of unaligne 147 information on the topic of unaligned memory accesses.
183 148
184 config ARCH_USE_BUILTIN_BSWAP 149 config ARCH_USE_BUILTIN_BSWAP
185 bool 150 bool
186 help 151 help
187 Modern versions of GCC (since 4.4) h !! 152 Modern versions of GCC (since 4.4) have builtin functions
188 for handling byte-swapping. Using th !! 153 for handling byte-swapping. Using these, instead of the old
189 inline assembler that the architectu !! 154 inline assembler that the architecture code provides in the
190 __arch_bswapXX() macros, allows the !! 155 __arch_bswapXX() macros, allows the compiler to see what's
191 happening and offers more opportunit !! 156 happening and offers more opportunity for optimisation. In
192 particular, the compiler will be abl !! 157 particular, the compiler will be able to combine the byteswap
193 with a nearby load or store and use !! 158 with a nearby load or store and use load-and-swap or
194 store-and-swap instructions if the a !! 159 store-and-swap instructions if the architecture has them. It
195 should almost *never* result in code !! 160 should almost *never* result in code which is worse than the
196 hand-coded assembler in <asm/swab.h> !! 161 hand-coded assembler in <asm/swab.h>. But just in case it
197 does, the use of the builtins is opt !! 162 does, the use of the builtins is optional.
198 !! 163
199 Any architecture with load-and-swap !! 164 Any architecture with load-and-swap or store-and-swap
200 instructions should set this. And it !! 165 instructions should set this. And it shouldn't hurt to set it
201 on architectures that don't have suc !! 166 on architectures that don't have such instructions.
202 167
203 config KRETPROBES 168 config KRETPROBES
204 def_bool y 169 def_bool y
205 depends on KPROBES && (HAVE_KRETPROBES !! 170 depends on KPROBES && HAVE_KRETPROBES
206 <<
207 config KRETPROBE_ON_RETHOOK <<
208 def_bool y <<
209 depends on HAVE_RETHOOK <<
210 depends on KRETPROBES <<
211 select RETHOOK <<
212 171
213 config USER_RETURN_NOTIFIER 172 config USER_RETURN_NOTIFIER
214 bool 173 bool
215 depends on HAVE_USER_RETURN_NOTIFIER 174 depends on HAVE_USER_RETURN_NOTIFIER
216 help 175 help
217 Provide a kernel-internal notificati 176 Provide a kernel-internal notification when a cpu is about to
218 switch to user mode. 177 switch to user mode.
219 178
220 config HAVE_IOREMAP_PROT 179 config HAVE_IOREMAP_PROT
221 bool 180 bool
222 181
223 config HAVE_KPROBES 182 config HAVE_KPROBES
224 bool 183 bool
225 184
226 config HAVE_KRETPROBES 185 config HAVE_KRETPROBES
227 bool 186 bool
228 187
229 config HAVE_OPTPROBES 188 config HAVE_OPTPROBES
230 bool 189 bool
231 190
232 config HAVE_KPROBES_ON_FTRACE 191 config HAVE_KPROBES_ON_FTRACE
233 bool 192 bool
234 193
235 config ARCH_CORRECT_STACKTRACE_ON_KRETPROBE 194 config ARCH_CORRECT_STACKTRACE_ON_KRETPROBE
236 bool 195 bool
237 help 196 help
238 Since kretprobes modifies return add 197 Since kretprobes modifies return address on the stack, the
239 stacktrace may see the kretprobe tra 198 stacktrace may see the kretprobe trampoline address instead
240 of correct one. If the architecture 199 of correct one. If the architecture stacktrace code and
241 unwinder can adjust such entries, se 200 unwinder can adjust such entries, select this configuration.
242 201
243 config HAVE_FUNCTION_ERROR_INJECTION 202 config HAVE_FUNCTION_ERROR_INJECTION
244 bool 203 bool
245 204
246 config HAVE_NMI 205 config HAVE_NMI
247 bool 206 bool
248 207
249 config HAVE_FUNCTION_DESCRIPTORS <<
250 bool <<
251 <<
252 config TRACE_IRQFLAGS_SUPPORT 208 config TRACE_IRQFLAGS_SUPPORT
253 bool 209 bool
254 210
255 config TRACE_IRQFLAGS_NMI_SUPPORT <<
256 bool <<
257 <<
258 # 211 #
259 # An arch should select this if it provides al 212 # An arch should select this if it provides all these things:
260 # 213 #
261 # task_pt_regs() in asm/process 214 # task_pt_regs() in asm/processor.h or asm/ptrace.h
262 # arch_has_single_step() if there is ha 215 # arch_has_single_step() if there is hardware single-step support
263 # arch_has_block_step() if there is ha 216 # arch_has_block_step() if there is hardware block-step support
264 # asm/syscall.h supplying asm- 217 # asm/syscall.h supplying asm-generic/syscall.h interface
265 # linux/regset.h user_regset in 218 # linux/regset.h user_regset interfaces
266 # CORE_DUMP_USE_REGSET #define'd in l 219 # CORE_DUMP_USE_REGSET #define'd in linux/elf.h
267 # TIF_SYSCALL_TRACE calls ptrace_r !! 220 # TIF_SYSCALL_TRACE calls tracehook_report_syscall_{entry,exit}
268 # TIF_NOTIFY_RESUME calls resume_u !! 221 # TIF_NOTIFY_RESUME calls tracehook_notify_resume()
>> 222 # signal delivery calls tracehook_signal_handler()
269 # 223 #
270 config HAVE_ARCH_TRACEHOOK 224 config HAVE_ARCH_TRACEHOOK
271 bool 225 bool
272 226
273 config HAVE_DMA_CONTIGUOUS 227 config HAVE_DMA_CONTIGUOUS
274 bool 228 bool
275 229
276 config GENERIC_SMP_IDLE_THREAD 230 config GENERIC_SMP_IDLE_THREAD
277 bool 231 bool
278 232
279 config GENERIC_IDLE_POLL_SETUP 233 config GENERIC_IDLE_POLL_SETUP
280 bool 234 bool
281 235
282 config ARCH_HAS_FORTIFY_SOURCE 236 config ARCH_HAS_FORTIFY_SOURCE
283 bool 237 bool
284 help 238 help
285 An architecture should select this w 239 An architecture should select this when it can successfully
286 build and run with CONFIG_FORTIFY_SO 240 build and run with CONFIG_FORTIFY_SOURCE.
287 241
288 # 242 #
289 # Select if the arch provides a historic keepi 243 # Select if the arch provides a historic keepinit alias for the retain_initrd
290 # command line option 244 # command line option
291 # 245 #
292 config ARCH_HAS_KEEPINITRD 246 config ARCH_HAS_KEEPINITRD
293 bool 247 bool
294 248
295 # Select if arch has all set_memory_ro/rw/x/nx 249 # Select if arch has all set_memory_ro/rw/x/nx() functions in asm/cacheflush.h
296 config ARCH_HAS_SET_MEMORY 250 config ARCH_HAS_SET_MEMORY
297 bool 251 bool
298 252
299 # Select if arch has all set_direct_map_invali 253 # Select if arch has all set_direct_map_invalid/default() functions
300 config ARCH_HAS_SET_DIRECT_MAP 254 config ARCH_HAS_SET_DIRECT_MAP
301 bool 255 bool
302 256
303 # 257 #
304 # Select if the architecture provides the arch 258 # Select if the architecture provides the arch_dma_set_uncached symbol to
305 # either provide an uncached segment alias for 259 # either provide an uncached segment alias for a DMA allocation, or
306 # to remap the page tables in place. 260 # to remap the page tables in place.
307 # 261 #
308 config ARCH_HAS_DMA_SET_UNCACHED 262 config ARCH_HAS_DMA_SET_UNCACHED
309 bool 263 bool
310 264
311 # 265 #
312 # Select if the architectures provides the arc 266 # Select if the architectures provides the arch_dma_clear_uncached symbol
313 # to undo an in-place page table remap for unc 267 # to undo an in-place page table remap for uncached access.
314 # 268 #
315 config ARCH_HAS_DMA_CLEAR_UNCACHED 269 config ARCH_HAS_DMA_CLEAR_UNCACHED
316 bool 270 bool
317 271
318 config ARCH_HAS_CPU_FINALIZE_INIT !! 272 # Select if arch init_task must go in the __init_task_data section
>> 273 config ARCH_TASK_STRUCT_ON_STACK
319 bool 274 bool
320 275
321 # The architecture has a per-task state that i !! 276 # Select if arch has its private alloc_task_struct() function
322 config ARCH_HAS_CPU_PASID !! 277 config ARCH_TASK_STRUCT_ALLOCATOR
323 bool 278 bool
324 select IOMMU_MM_DATA <<
325 279
326 config HAVE_ARCH_THREAD_STRUCT_WHITELIST 280 config HAVE_ARCH_THREAD_STRUCT_WHITELIST
327 bool 281 bool
>> 282 depends on !ARCH_TASK_STRUCT_ALLOCATOR
328 help 283 help
329 An architecture should select this t 284 An architecture should select this to provide hardened usercopy
330 knowledge about what region of the t 285 knowledge about what region of the thread_struct should be
331 whitelisted for copying to userspace 286 whitelisted for copying to userspace. Normally this is only the
332 FPU registers. Specifically, arch_th 287 FPU registers. Specifically, arch_thread_struct_whitelist()
333 should be implemented. Without this, 288 should be implemented. Without this, the entire thread_struct
334 field in task_struct will be left wh 289 field in task_struct will be left whitelisted.
335 290
>> 291 # Select if arch has its private alloc_thread_stack() function
>> 292 config ARCH_THREAD_STACK_ALLOCATOR
>> 293 bool
>> 294
336 # Select if arch wants to size task_struct dyn 295 # Select if arch wants to size task_struct dynamically via arch_task_struct_size:
337 config ARCH_WANTS_DYNAMIC_TASK_STRUCT 296 config ARCH_WANTS_DYNAMIC_TASK_STRUCT
338 bool 297 bool
339 298
340 config ARCH_WANTS_NO_INSTR 299 config ARCH_WANTS_NO_INSTR
341 bool 300 bool
342 help 301 help
343 An architecture should select this i 302 An architecture should select this if the noinstr macro is being used on
344 functions to denote that the toolcha 303 functions to denote that the toolchain should avoid instrumenting such
345 functions and is required for correc 304 functions and is required for correctness.
346 305
347 config ARCH_32BIT_OFF_T 306 config ARCH_32BIT_OFF_T
348 bool 307 bool
349 depends on !64BIT 308 depends on !64BIT
350 help 309 help
351 All new 32-bit architectures should 310 All new 32-bit architectures should have 64-bit off_t type on
352 userspace side which corresponds to 311 userspace side which corresponds to the loff_t kernel type. This
353 is the requirement for modern ABIs. 312 is the requirement for modern ABIs. Some existing architectures
354 still support 32-bit off_t. This opt 313 still support 32-bit off_t. This option is enabled for all such
355 architectures explicitly. 314 architectures explicitly.
356 315
357 # Selected by 64 bit architectures which have 316 # Selected by 64 bit architectures which have a 32 bit f_tinode in struct ustat
358 config ARCH_32BIT_USTAT_F_TINODE 317 config ARCH_32BIT_USTAT_F_TINODE
359 bool 318 bool
360 319
361 config HAVE_ASM_MODVERSIONS 320 config HAVE_ASM_MODVERSIONS
362 bool 321 bool
363 help 322 help
364 This symbol should be selected by an 323 This symbol should be selected by an architecture if it provides
365 <asm/asm-prototypes.h> to support th 324 <asm/asm-prototypes.h> to support the module versioning for symbols
366 exported from assembly code. 325 exported from assembly code.
367 326
368 config HAVE_REGS_AND_STACK_ACCESS_API 327 config HAVE_REGS_AND_STACK_ACCESS_API
369 bool 328 bool
370 help 329 help
371 This symbol should be selected by an 330 This symbol should be selected by an architecture if it supports
372 the API needed to access registers a 331 the API needed to access registers and stack entries from pt_regs,
373 declared in asm/ptrace.h 332 declared in asm/ptrace.h
374 For example the kprobes-based event 333 For example the kprobes-based event tracer needs this API.
375 334
376 config HAVE_RSEQ 335 config HAVE_RSEQ
377 bool 336 bool
378 depends on HAVE_REGS_AND_STACK_ACCESS_ 337 depends on HAVE_REGS_AND_STACK_ACCESS_API
379 help 338 help
380 This symbol should be selected by an 339 This symbol should be selected by an architecture if it
381 supports an implementation of restar 340 supports an implementation of restartable sequences.
382 341
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 342 config HAVE_FUNCTION_ARG_ACCESS_API
390 bool 343 bool
391 help 344 help
392 This symbol should be selected by an 345 This symbol should be selected by an architecture if it supports
393 the API needed to access function ar 346 the API needed to access function arguments from pt_regs,
394 declared in asm/ptrace.h 347 declared in asm/ptrace.h
395 348
396 config HAVE_HW_BREAKPOINT 349 config HAVE_HW_BREAKPOINT
397 bool 350 bool
398 depends on PERF_EVENTS 351 depends on PERF_EVENTS
399 352
400 config HAVE_MIXED_BREAKPOINTS_REGS 353 config HAVE_MIXED_BREAKPOINTS_REGS
401 bool 354 bool
402 depends on HAVE_HW_BREAKPOINT 355 depends on HAVE_HW_BREAKPOINT
403 help 356 help
404 Depending on the arch implementation 357 Depending on the arch implementation of hardware breakpoints,
405 some of them have separate registers 358 some of them have separate registers for data and instruction
406 breakpoints addresses, others have m 359 breakpoints addresses, others have mixed registers to store
407 them but define the access type in a 360 them but define the access type in a control register.
408 Select this option if your arch impl 361 Select this option if your arch implements breakpoints under the
409 latter fashion. 362 latter fashion.
410 363
411 config HAVE_USER_RETURN_NOTIFIER 364 config HAVE_USER_RETURN_NOTIFIER
412 bool 365 bool
413 366
414 config HAVE_PERF_EVENTS_NMI 367 config HAVE_PERF_EVENTS_NMI
415 bool 368 bool
416 help 369 help
417 System hardware can generate an NMI 370 System hardware can generate an NMI using the perf event
418 subsystem. Also has support for cal 371 subsystem. Also has support for calculating CPU cycle events
419 to determine how many clock cycles i 372 to determine how many clock cycles in a given period.
420 373
421 config HAVE_HARDLOCKUP_DETECTOR_PERF 374 config HAVE_HARDLOCKUP_DETECTOR_PERF
422 bool 375 bool
423 depends on HAVE_PERF_EVENTS_NMI 376 depends on HAVE_PERF_EVENTS_NMI
424 help 377 help
425 The arch chooses to use the generic 378 The arch chooses to use the generic perf-NMI-based hardlockup
426 detector. Must define HAVE_PERF_EVEN 379 detector. Must define HAVE_PERF_EVENTS_NMI.
427 380
428 config HAVE_HARDLOCKUP_DETECTOR_ARCH !! 381 config HAVE_NMI_WATCHDOG
>> 382 depends on HAVE_NMI
429 bool 383 bool
430 help 384 help
431 The arch provides its own hardlockup !! 385 The arch provides a low level NMI watchdog. It provides
432 of the generic ones. !! 386 asm/nmi.h, and defines its own arch_touch_nmi_watchdog().
433 387
434 It uses the same command line parame !! 388 config HAVE_HARDLOCKUP_DETECTOR_ARCH
435 as the generic hardlockup detectors. !! 389 bool
>> 390 select HAVE_NMI_WATCHDOG
>> 391 help
>> 392 The arch chooses to provide its own hardlockup detector, which is
>> 393 a superset of the HAVE_NMI_WATCHDOG. It also conforms to config
>> 394 interfaces and parameters provided by hardlockup detector subsystem.
436 395
437 config HAVE_PERF_REGS 396 config HAVE_PERF_REGS
438 bool 397 bool
439 help 398 help
440 Support selective register dumps for 399 Support selective register dumps for perf events. This includes
441 bit-mapping of each registers and a 400 bit-mapping of each registers and a unique architecture id.
442 401
443 config HAVE_PERF_USER_STACK_DUMP 402 config HAVE_PERF_USER_STACK_DUMP
444 bool 403 bool
445 help 404 help
446 Support user stack dumps for perf ev 405 Support user stack dumps for perf event samples. This needs
447 access to the user stack pointer whi 406 access to the user stack pointer which is not unified across
448 architectures. 407 architectures.
449 408
450 config HAVE_ARCH_JUMP_LABEL 409 config HAVE_ARCH_JUMP_LABEL
451 bool 410 bool
452 411
453 config HAVE_ARCH_JUMP_LABEL_RELATIVE 412 config HAVE_ARCH_JUMP_LABEL_RELATIVE
454 bool 413 bool
455 414
456 config MMU_GATHER_TABLE_FREE 415 config MMU_GATHER_TABLE_FREE
457 bool 416 bool
458 417
459 config MMU_GATHER_RCU_TABLE_FREE 418 config MMU_GATHER_RCU_TABLE_FREE
460 bool 419 bool
461 select MMU_GATHER_TABLE_FREE 420 select MMU_GATHER_TABLE_FREE
462 421
463 config MMU_GATHER_PAGE_SIZE 422 config MMU_GATHER_PAGE_SIZE
464 bool 423 bool
465 424
466 config MMU_GATHER_NO_RANGE 425 config MMU_GATHER_NO_RANGE
467 bool 426 bool
468 select MMU_GATHER_MERGE_VMAS <<
469 <<
470 config MMU_GATHER_NO_FLUSH_CACHE <<
471 bool <<
472 <<
473 config MMU_GATHER_MERGE_VMAS <<
474 bool <<
475 427
476 config MMU_GATHER_NO_GATHER 428 config MMU_GATHER_NO_GATHER
477 bool 429 bool
478 depends on MMU_GATHER_TABLE_FREE 430 depends on MMU_GATHER_TABLE_FREE
479 431
480 config ARCH_WANT_IRQS_OFF_ACTIVATE_MM 432 config ARCH_WANT_IRQS_OFF_ACTIVATE_MM
481 bool 433 bool
482 help 434 help
483 Temporary select until all architect 435 Temporary select until all architectures can be converted to have
484 irqs disabled over activate_mm. Arch 436 irqs disabled over activate_mm. Architectures that do IPI based TLB
485 shootdowns should enable this. 437 shootdowns should enable this.
486 438
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 439 config ARCH_HAVE_NMI_SAFE_CMPXCHG
520 bool 440 bool
521 441
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 442 config HAVE_ALIGNED_STRUCT_PAGE
535 bool 443 bool
536 help 444 help
537 This makes sure that struct pages ar 445 This makes sure that struct pages are double word aligned and that
538 e.g. the SLUB allocator can perform 446 e.g. the SLUB allocator can perform double word atomic operations
539 on a struct page for better performa 447 on a struct page for better performance. However selecting this
540 might increase the size of a struct 448 might increase the size of a struct page by a word.
541 449
542 config HAVE_CMPXCHG_LOCAL 450 config HAVE_CMPXCHG_LOCAL
543 bool 451 bool
544 452
545 config HAVE_CMPXCHG_DOUBLE 453 config HAVE_CMPXCHG_DOUBLE
546 bool 454 bool
547 455
548 config ARCH_WEAK_RELEASE_ACQUIRE 456 config ARCH_WEAK_RELEASE_ACQUIRE
549 bool 457 bool
550 458
551 config ARCH_WANT_IPC_PARSE_VERSION 459 config ARCH_WANT_IPC_PARSE_VERSION
552 bool 460 bool
553 461
554 config ARCH_WANT_COMPAT_IPC_PARSE_VERSION 462 config ARCH_WANT_COMPAT_IPC_PARSE_VERSION
555 bool 463 bool
556 464
557 config ARCH_WANT_OLD_COMPAT_IPC 465 config ARCH_WANT_OLD_COMPAT_IPC
558 select ARCH_WANT_COMPAT_IPC_PARSE_VERS 466 select ARCH_WANT_COMPAT_IPC_PARSE_VERSION
559 bool 467 bool
560 468
561 config HAVE_ARCH_SECCOMP 469 config HAVE_ARCH_SECCOMP
562 bool 470 bool
563 help 471 help
564 An arch should select this symbol to 472 An arch should select this symbol to support seccomp mode 1 (the fixed
565 syscall policy), and must provide an 473 syscall policy), and must provide an overrides for __NR_seccomp_sigreturn,
566 and compat syscalls if the asm-gener 474 and compat syscalls if the asm-generic/seccomp.h defaults need adjustment:
567 - __NR_seccomp_read_32 475 - __NR_seccomp_read_32
568 - __NR_seccomp_write_32 476 - __NR_seccomp_write_32
569 - __NR_seccomp_exit_32 477 - __NR_seccomp_exit_32
570 - __NR_seccomp_sigreturn_32 478 - __NR_seccomp_sigreturn_32
571 479
572 config HAVE_ARCH_SECCOMP_FILTER 480 config HAVE_ARCH_SECCOMP_FILTER
573 bool 481 bool
574 select HAVE_ARCH_SECCOMP 482 select HAVE_ARCH_SECCOMP
575 help 483 help
576 An arch should select this symbol if 484 An arch should select this symbol if it provides all of these things:
577 - all the requirements for HAVE_ARCH 485 - all the requirements for HAVE_ARCH_SECCOMP
578 - syscall_get_arch() 486 - syscall_get_arch()
579 - syscall_get_arguments() 487 - syscall_get_arguments()
580 - syscall_rollback() 488 - syscall_rollback()
581 - syscall_set_return_value() 489 - syscall_set_return_value()
582 - SIGSYS siginfo_t support 490 - SIGSYS siginfo_t support
583 - secure_computing is called from a 491 - secure_computing is called from a ptrace_event()-safe context
584 - secure_computing return value is c 492 - secure_computing return value is checked and a return value of -1
585 results in the system call being s 493 results in the system call being skipped immediately.
586 - seccomp syscall wired up 494 - seccomp syscall wired up
587 - if !HAVE_SPARSE_SYSCALL_NR, have S 495 - if !HAVE_SPARSE_SYSCALL_NR, have SECCOMP_ARCH_NATIVE,
588 SECCOMP_ARCH_NATIVE_NR, SECCOMP_AR 496 SECCOMP_ARCH_NATIVE_NR, SECCOMP_ARCH_NATIVE_NAME defined. If
589 COMPAT is supported, have the SECC 497 COMPAT is supported, have the SECCOMP_ARCH_COMPAT* defines too.
590 498
591 config SECCOMP 499 config SECCOMP
592 prompt "Enable seccomp to safely execu 500 prompt "Enable seccomp to safely execute untrusted bytecode"
593 def_bool y 501 def_bool y
594 depends on HAVE_ARCH_SECCOMP 502 depends on HAVE_ARCH_SECCOMP
595 help 503 help
596 This kernel feature is useful for nu 504 This kernel feature is useful for number crunching applications
597 that may need to handle untrusted by 505 that may need to handle untrusted bytecode during their
598 execution. By using pipes or other t 506 execution. By using pipes or other transports made available
599 to the process as file descriptors s 507 to the process as file descriptors supporting the read/write
600 syscalls, it's possible to isolate t 508 syscalls, it's possible to isolate those applications in their
601 own address space using seccomp. Onc 509 own address space using seccomp. Once seccomp is enabled via
602 prctl(PR_SET_SECCOMP) or the seccomp 510 prctl(PR_SET_SECCOMP) or the seccomp() syscall, it cannot be
603 disabled and the task is only allowe 511 disabled and the task is only allowed to execute a few safe
604 syscalls defined by each seccomp mod 512 syscalls defined by each seccomp mode.
605 513
606 If unsure, say Y. 514 If unsure, say Y.
607 515
608 config SECCOMP_FILTER 516 config SECCOMP_FILTER
609 def_bool y 517 def_bool y
610 depends on HAVE_ARCH_SECCOMP_FILTER && 518 depends on HAVE_ARCH_SECCOMP_FILTER && SECCOMP && NET
611 help 519 help
612 Enable tasks to build secure computi 520 Enable tasks to build secure computing environments defined
613 in terms of Berkeley Packet Filter p 521 in terms of Berkeley Packet Filter programs which implement
614 task-defined system call filtering p 522 task-defined system call filtering polices.
615 523
616 See Documentation/userspace-api/secc 524 See Documentation/userspace-api/seccomp_filter.rst for details.
617 525
618 config SECCOMP_CACHE_DEBUG 526 config SECCOMP_CACHE_DEBUG
619 bool "Show seccomp filter cache status 527 bool "Show seccomp filter cache status in /proc/pid/seccomp_cache"
620 depends on SECCOMP_FILTER && !HAVE_SPA 528 depends on SECCOMP_FILTER && !HAVE_SPARSE_SYSCALL_NR
621 depends on PROC_FS 529 depends on PROC_FS
622 help 530 help
623 This enables the /proc/pid/seccomp_c 531 This enables the /proc/pid/seccomp_cache interface to monitor
624 seccomp cache data. The file format 532 seccomp cache data. The file format is subject to change. Reading
625 the file requires CAP_SYS_ADMIN. 533 the file requires CAP_SYS_ADMIN.
626 534
627 This option is for debugging only. E 535 This option is for debugging only. Enabling presents the risk that
628 an adversary may be able to infer th 536 an adversary may be able to infer the seccomp filter logic.
629 537
630 If unsure, say N. 538 If unsure, say N.
631 539
632 config HAVE_ARCH_STACKLEAK 540 config HAVE_ARCH_STACKLEAK
633 bool 541 bool
634 help 542 help
635 An architecture should select this i 543 An architecture should select this if it has the code which
636 fills the used part of the kernel st 544 fills the used part of the kernel stack with the STACKLEAK_POISON
637 value before returning from system c 545 value before returning from system calls.
638 546
639 config HAVE_STACKPROTECTOR 547 config HAVE_STACKPROTECTOR
640 bool 548 bool
641 help 549 help
642 An arch should select this symbol if 550 An arch should select this symbol if:
643 - it has implemented a stack canary 551 - it has implemented a stack canary (e.g. __stack_chk_guard)
644 552
645 config STACKPROTECTOR 553 config STACKPROTECTOR
646 bool "Stack Protector buffer overflow 554 bool "Stack Protector buffer overflow detection"
647 depends on HAVE_STACKPROTECTOR 555 depends on HAVE_STACKPROTECTOR
648 depends on $(cc-option,-fstack-protect 556 depends on $(cc-option,-fstack-protector)
649 default y 557 default y
650 help 558 help
651 This option turns on the "stack-prot 559 This option turns on the "stack-protector" GCC feature. This
652 feature puts, at the beginning of fu 560 feature puts, at the beginning of functions, a canary value on
653 the stack just before the return add 561 the stack just before the return address, and validates
654 the value just before actually retur 562 the value just before actually returning. Stack based buffer
655 overflows (that need to overwrite th 563 overflows (that need to overwrite this return address) now also
656 overwrite the canary, which gets det 564 overwrite the canary, which gets detected and the attack is then
657 neutralized via a kernel panic. 565 neutralized via a kernel panic.
658 566
659 Functions will have the stack-protec 567 Functions will have the stack-protector canary logic added if they
660 have an 8-byte or larger character a 568 have an 8-byte or larger character array on the stack.
661 569
662 This feature requires gcc version 4. 570 This feature requires gcc version 4.2 or above, or a distribution
663 gcc with the feature backported ("-f 571 gcc with the feature backported ("-fstack-protector").
664 572
665 On an x86 "defconfig" build, this fe 573 On an x86 "defconfig" build, this feature adds canary checks to
666 about 3% of all kernel functions, wh 574 about 3% of all kernel functions, which increases kernel code size
667 by about 0.3%. 575 by about 0.3%.
668 576
669 config STACKPROTECTOR_STRONG 577 config STACKPROTECTOR_STRONG
670 bool "Strong Stack Protector" 578 bool "Strong Stack Protector"
671 depends on STACKPROTECTOR 579 depends on STACKPROTECTOR
672 depends on $(cc-option,-fstack-protect 580 depends on $(cc-option,-fstack-protector-strong)
673 default y 581 default y
674 help 582 help
675 Functions will have the stack-protec 583 Functions will have the stack-protector canary logic added in any
676 of the following conditions: 584 of the following conditions:
677 585
678 - local variable's address used as p 586 - local variable's address used as part of the right hand side of an
679 assignment or function argument 587 assignment or function argument
680 - local variable is an array (or uni 588 - local variable is an array (or union containing an array),
681 regardless of array type or length 589 regardless of array type or length
682 - uses register local variables 590 - uses register local variables
683 591
684 This feature requires gcc version 4. 592 This feature requires gcc version 4.9 or above, or a distribution
685 gcc with the feature backported ("-f 593 gcc with the feature backported ("-fstack-protector-strong").
686 594
687 On an x86 "defconfig" build, this fe 595 On an x86 "defconfig" build, this feature adds canary checks to
688 about 20% of all kernel functions, w 596 about 20% of all kernel functions, which increases the kernel code
689 size by about 2%. 597 size by about 2%.
690 598
691 config ARCH_SUPPORTS_SHADOW_CALL_STACK 599 config ARCH_SUPPORTS_SHADOW_CALL_STACK
692 bool 600 bool
693 help 601 help
694 An architecture should select this i !! 602 An architecture should select this if it supports Clang's Shadow
695 Shadow Call Stack and implements run !! 603 Call Stack and implements runtime support for shadow stack
696 switching. 604 switching.
697 605
698 config SHADOW_CALL_STACK 606 config SHADOW_CALL_STACK
699 bool "Shadow Call Stack" !! 607 bool "Clang Shadow Call Stack"
700 depends on ARCH_SUPPORTS_SHADOW_CALL_S !! 608 depends on CC_IS_CLANG && ARCH_SUPPORTS_SHADOW_CALL_STACK
701 depends on DYNAMIC_FTRACE_WITH_ARGS || !! 609 depends on DYNAMIC_FTRACE_WITH_REGS || !FUNCTION_GRAPH_TRACER
702 depends on MMU !! 610 help
703 help !! 611 This option enables Clang's Shadow Call Stack, which uses a
704 This option enables the compiler's S !! 612 shadow stack to protect function return addresses from being
705 uses a shadow stack to protect funct !! 613 overwritten by an attacker. More information can be found in
706 being overwritten by an attacker. Mo !! 614 Clang's documentation:
707 in the compiler's documentation: <<
708 615
709 - Clang: https://clang.llvm.org/docs !! 616 https://clang.llvm.org/docs/ShadowCallStack.html
710 - GCC: https://gcc.gnu.org/onlinedoc <<
711 617
712 Note that security guarantees in the 618 Note that security guarantees in the kernel differ from the
713 ones documented for user space. The 619 ones documented for user space. The kernel must store addresses
714 of shadow stacks in memory, which me 620 of shadow stacks in memory, which means an attacker capable of
715 reading and writing arbitrary memory 621 reading and writing arbitrary memory may be able to locate them
716 and hijack control flow by modifying 622 and hijack control flow by modifying the stacks.
717 623
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 624 config LTO
726 bool 625 bool
727 help 626 help
728 Selected if the kernel will be built 627 Selected if the kernel will be built using the compiler's LTO feature.
729 628
730 config LTO_CLANG 629 config LTO_CLANG
731 bool 630 bool
732 select LTO 631 select LTO
733 help 632 help
734 Selected if the kernel will be built 633 Selected if the kernel will be built using Clang's LTO feature.
735 634
736 config ARCH_SUPPORTS_LTO_CLANG 635 config ARCH_SUPPORTS_LTO_CLANG
737 bool 636 bool
738 help 637 help
739 An architecture should select this o 638 An architecture should select this option if it supports:
740 - compiling with Clang, 639 - compiling with Clang,
741 - compiling inline assembly with Cla 640 - compiling inline assembly with Clang's integrated assembler,
742 - and linking with LLD. 641 - and linking with LLD.
743 642
744 config ARCH_SUPPORTS_LTO_CLANG_THIN 643 config ARCH_SUPPORTS_LTO_CLANG_THIN
745 bool 644 bool
746 help 645 help
747 An architecture should select this o 646 An architecture should select this option if it can support Clang's
748 ThinLTO mode. 647 ThinLTO mode.
749 648
750 config HAS_LTO_CLANG 649 config HAS_LTO_CLANG
751 def_bool y 650 def_bool y
752 depends on CC_IS_CLANG && LD_IS_LLD && !! 651 # Clang >= 11: https://github.com/ClangBuiltLinux/linux/issues/510
>> 652 depends on CC_IS_CLANG && CLANG_VERSION >= 110000 && LD_IS_LLD && AS_IS_LLVM
753 depends on $(success,$(NM) --help | he 653 depends on $(success,$(NM) --help | head -n 1 | grep -qi llvm)
754 depends on $(success,$(AR) --help | he 654 depends on $(success,$(AR) --help | head -n 1 | grep -qi llvm)
755 depends on ARCH_SUPPORTS_LTO_CLANG 655 depends on ARCH_SUPPORTS_LTO_CLANG
756 depends on !FTRACE_MCOUNT_USE_RECORDMC 656 depends on !FTRACE_MCOUNT_USE_RECORDMCOUNT
757 # https://github.com/ClangBuiltLinux/l !! 657 depends on !KASAN || KASAN_HW_TAGS
758 depends on (!KASAN || KASAN_HW_TAGS || <<
759 depends on (!KCOV || CLANG_VERSION >= <<
760 depends on !GCOV_KERNEL 658 depends on !GCOV_KERNEL
761 help 659 help
762 The compiler and Kconfig options sup 660 The compiler and Kconfig options support building with Clang's
763 LTO. 661 LTO.
764 662
765 choice 663 choice
766 prompt "Link Time Optimization (LTO)" 664 prompt "Link Time Optimization (LTO)"
767 default LTO_NONE 665 default LTO_NONE
768 help 666 help
769 This option enables Link Time Optimi 667 This option enables Link Time Optimization (LTO), which allows the
770 compiler to optimize binaries global 668 compiler to optimize binaries globally.
771 669
772 If unsure, select LTO_NONE. Note tha 670 If unsure, select LTO_NONE. Note that LTO is very resource-intensive
773 so it's disabled by default. 671 so it's disabled by default.
774 672
775 config LTO_NONE 673 config LTO_NONE
776 bool "None" 674 bool "None"
777 help 675 help
778 Build the kernel normally, without L 676 Build the kernel normally, without Link Time Optimization (LTO).
779 677
780 config LTO_CLANG_FULL 678 config LTO_CLANG_FULL
781 bool "Clang Full LTO (EXPERIMENTAL)" 679 bool "Clang Full LTO (EXPERIMENTAL)"
782 depends on HAS_LTO_CLANG 680 depends on HAS_LTO_CLANG
783 depends on !COMPILE_TEST 681 depends on !COMPILE_TEST
784 select LTO_CLANG 682 select LTO_CLANG
785 help 683 help
786 This option enables Clang's full Lin !! 684 This option enables Clang's full Link Time Optimization (LTO), which
787 allows the compiler to optimize the !! 685 allows the compiler to optimize the kernel globally. If you enable
788 this option, the compiler generates !! 686 this option, the compiler generates LLVM bitcode instead of ELF
789 object files, and the actual compila !! 687 object files, and the actual compilation from bitcode happens at
790 the LTO link step, which may take se !! 688 the LTO link step, which may take several minutes depending on the
791 kernel configuration. More informati !! 689 kernel configuration. More information can be found from LLVM's
792 documentation: !! 690 documentation:
793 691
794 https://llvm.org/docs/LinkTimeOpti 692 https://llvm.org/docs/LinkTimeOptimization.html
795 693
796 During link time, this option can us 694 During link time, this option can use a large amount of RAM, and
797 may take much longer than the ThinLT 695 may take much longer than the ThinLTO option.
798 696
799 config LTO_CLANG_THIN 697 config LTO_CLANG_THIN
800 bool "Clang ThinLTO (EXPERIMENTAL)" 698 bool "Clang ThinLTO (EXPERIMENTAL)"
801 depends on HAS_LTO_CLANG && ARCH_SUPPO 699 depends on HAS_LTO_CLANG && ARCH_SUPPORTS_LTO_CLANG_THIN
802 select LTO_CLANG 700 select LTO_CLANG
803 help 701 help
804 This option enables Clang's ThinLTO, 702 This option enables Clang's ThinLTO, which allows for parallel
805 optimization and faster incremental 703 optimization and faster incremental compiles compared to the
806 CONFIG_LTO_CLANG_FULL option. More i 704 CONFIG_LTO_CLANG_FULL option. More information can be found
807 from Clang's documentation: 705 from Clang's documentation:
808 706
809 https://clang.llvm.org/docs/ThinLT 707 https://clang.llvm.org/docs/ThinLTO.html
810 708
811 If unsure, say Y. 709 If unsure, say Y.
812 endchoice 710 endchoice
813 711
814 config ARCH_SUPPORTS_CFI_CLANG 712 config ARCH_SUPPORTS_CFI_CLANG
815 bool 713 bool
816 help 714 help
817 An architecture should select this o 715 An architecture should select this option if it can support Clang's
818 Control-Flow Integrity (CFI) checkin 716 Control-Flow Integrity (CFI) checking.
819 717
820 config ARCH_USES_CFI_TRAPS <<
821 bool <<
822 <<
823 config CFI_CLANG 718 config CFI_CLANG
824 bool "Use Clang's Control Flow Integri 719 bool "Use Clang's Control Flow Integrity (CFI)"
825 depends on ARCH_SUPPORTS_CFI_CLANG !! 720 depends on LTO_CLANG && ARCH_SUPPORTS_CFI_CLANG
826 depends on $(cc-option,-fsanitize=kcfi !! 721 # Clang >= 12:
>> 722 # - https://bugs.llvm.org/show_bug.cgi?id=46258
>> 723 # - https://bugs.llvm.org/show_bug.cgi?id=47479
>> 724 depends on CLANG_VERSION >= 120000
>> 725 select KALLSYMS
827 help 726 help
828 This option enables Clang's forward- !! 727 This option enables Clang’s forward-edge Control Flow Integrity
829 (CFI) checking, where the compiler i 728 (CFI) checking, where the compiler injects a runtime check to each
830 indirect function call to ensure the 729 indirect function call to ensure the target is a valid function with
831 the correct static type. This restri 730 the correct static type. This restricts possible call targets and
832 makes it more difficult for an attac 731 makes it more difficult for an attacker to exploit bugs that allow
833 the modification of stored function 732 the modification of stored function pointers. More information can be
834 found from Clang's documentation: 733 found from Clang's documentation:
835 734
836 https://clang.llvm.org/docs/Contro 735 https://clang.llvm.org/docs/ControlFlowIntegrity.html
837 736
838 config CFI_ICALL_NORMALIZE_INTEGERS !! 737 config CFI_CLANG_SHADOW
839 bool "Normalize CFI tags for integers" !! 738 bool "Use CFI shadow to speed up cross-module checks"
840 depends on CFI_CLANG !! 739 default y
841 depends on HAVE_CFI_ICALL_NORMALIZE_IN !! 740 depends on CFI_CLANG && MODULES
842 help 741 help
843 This option normalizes the CFI tags !! 742 If you select this option, the kernel builds a fast look-up table of
844 integer types of the same size and s !! 743 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 || <<
859 744
860 config HAVE_CFI_ICALL_NORMALIZE_INTEGERS_RUSTC !! 745 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 <<
867 746
868 config CFI_PERMISSIVE 747 config CFI_PERMISSIVE
869 bool "Use CFI in permissive mode" 748 bool "Use CFI in permissive mode"
870 depends on CFI_CLANG 749 depends on CFI_CLANG
871 help 750 help
872 When selected, Control Flow Integrit 751 When selected, Control Flow Integrity (CFI) violations result in a
873 warning instead of a kernel panic. T 752 warning instead of a kernel panic. This option should only be used
874 for finding indirect call type misma 753 for finding indirect call type mismatches during development.
875 754
876 If unsure, say N. 755 If unsure, say N.
877 756
878 config HAVE_ARCH_WITHIN_STACK_FRAMES 757 config HAVE_ARCH_WITHIN_STACK_FRAMES
879 bool 758 bool
880 help 759 help
881 An architecture should select this i 760 An architecture should select this if it can walk the kernel stack
882 frames to determine if an object is 761 frames to determine if an object is part of either the arguments
883 or local variables (i.e. that it exc 762 or local variables (i.e. that it excludes saved return addresses,
884 and similar) by implementing an inli 763 and similar) by implementing an inline arch_within_stack_frames(),
885 which is used by CONFIG_HARDENED_USE 764 which is used by CONFIG_HARDENED_USERCOPY.
886 765
887 config HAVE_CONTEXT_TRACKING_USER !! 766 config HAVE_CONTEXT_TRACKING
888 bool 767 bool
889 help 768 help
890 Provide kernel/user boundaries probe 769 Provide kernel/user boundaries probes necessary for subsystems
891 that need it, such as userspace RCU 770 that need it, such as userspace RCU extended quiescent state.
892 Syscalls need to be wrapped inside u 771 Syscalls need to be wrapped inside user_exit()-user_enter(), either
893 optimized behind static key or throu 772 optimized behind static key or through the slow path using TIF_NOHZ
894 flag. Exceptions handlers must be wr 773 flag. Exceptions handlers must be wrapped as well. Irqs are already
895 protected inside ct_irq_enter/ct_irq !! 774 protected inside rcu_irq_enter/rcu_irq_exit() but preemption or signal
896 handling on irq exit still need to b 775 handling on irq exit still need to be protected.
897 776
898 config HAVE_CONTEXT_TRACKING_USER_OFFSTACK !! 777 config HAVE_CONTEXT_TRACKING_OFFSTACK
899 bool 778 bool
900 help 779 help
901 Architecture neither relies on excep 780 Architecture neither relies on exception_enter()/exception_exit()
902 nor on schedule_user(). Also preempt 781 nor on schedule_user(). Also preempt_schedule_notrace() and
903 preempt_schedule_irq() can't be call 782 preempt_schedule_irq() can't be called in a preemptible section
904 while context tracking is CT_STATE_U !! 783 while context tracking is CONTEXT_USER. This feature reflects a sane
905 entry implementation where the follo 784 entry implementation where the following requirements are met on
906 critical entry code, ie: before user 785 critical entry code, ie: before user_exit() or after user_enter():
907 786
908 - Critical entry code isn't preempti 787 - Critical entry code isn't preemptible (or better yet:
909 not interruptible). 788 not interruptible).
910 - No use of RCU read side critical s !! 789 - No use of RCU read side critical sections, unless rcu_nmi_enter()
911 got called. 790 got called.
912 - No use of instrumentation, unless 791 - No use of instrumentation, unless instrumentation_begin() got
913 called. 792 called.
914 793
915 config HAVE_TIF_NOHZ 794 config HAVE_TIF_NOHZ
916 bool 795 bool
917 help 796 help
918 Arch relies on TIF_NOHZ and syscall 797 Arch relies on TIF_NOHZ and syscall slow path to implement context
919 tracking calls to user_enter()/user_ 798 tracking calls to user_enter()/user_exit().
920 799
921 config HAVE_VIRT_CPU_ACCOUNTING 800 config HAVE_VIRT_CPU_ACCOUNTING
922 bool 801 bool
923 802
924 config HAVE_VIRT_CPU_ACCOUNTING_IDLE 803 config HAVE_VIRT_CPU_ACCOUNTING_IDLE
925 bool 804 bool
926 help 805 help
927 Architecture has its own way to acco 806 Architecture has its own way to account idle CPU time and therefore
928 doesn't implement vtime_account_idle 807 doesn't implement vtime_account_idle().
929 808
930 config ARCH_HAS_SCALED_CPUTIME 809 config ARCH_HAS_SCALED_CPUTIME
931 bool 810 bool
932 811
933 config HAVE_VIRT_CPU_ACCOUNTING_GEN 812 config HAVE_VIRT_CPU_ACCOUNTING_GEN
934 bool 813 bool
935 default y if 64BIT 814 default y if 64BIT
936 help 815 help
937 With VIRT_CPU_ACCOUNTING_GEN, cputim 816 With VIRT_CPU_ACCOUNTING_GEN, cputime_t becomes 64-bit.
938 Before enabling this option, arch co 817 Before enabling this option, arch code must be audited
939 to ensure there are no races in conc 818 to ensure there are no races in concurrent read/write of
940 cputime_t. For example, reading/writ 819 cputime_t. For example, reading/writing 64-bit cputime_t on
941 some 32-bit arches may require multi 820 some 32-bit arches may require multiple accesses, so proper
942 locking is needed to protect against 821 locking is needed to protect against concurrent accesses.
943 822
944 config HAVE_IRQ_TIME_ACCOUNTING 823 config HAVE_IRQ_TIME_ACCOUNTING
945 bool 824 bool
946 help 825 help
947 Archs need to ensure they use a high 826 Archs need to ensure they use a high enough resolution clock to
948 support irq time accounting and then 827 support irq time accounting and then call enable_sched_clock_irqtime().
949 828
950 config HAVE_MOVE_PUD 829 config HAVE_MOVE_PUD
951 bool 830 bool
952 help 831 help
953 Architectures that select this are a 832 Architectures that select this are able to move page tables at the
954 PUD level. If there are only 3 page 833 PUD level. If there are only 3 page table levels, the move effectively
955 happens at the PGD level. 834 happens at the PGD level.
956 835
957 config HAVE_MOVE_PMD 836 config HAVE_MOVE_PMD
958 bool 837 bool
959 help 838 help
960 Archs that select this are able to m 839 Archs that select this are able to move page tables at the PMD level.
961 840
962 config HAVE_ARCH_TRANSPARENT_HUGEPAGE 841 config HAVE_ARCH_TRANSPARENT_HUGEPAGE
963 bool 842 bool
964 843
965 config HAVE_ARCH_TRANSPARENT_HUGEPAGE_PUD 844 config HAVE_ARCH_TRANSPARENT_HUGEPAGE_PUD
966 bool 845 bool
967 846
968 config HAVE_ARCH_HUGE_VMAP 847 config HAVE_ARCH_HUGE_VMAP
969 bool 848 bool
970 849
971 # 850 #
972 # Archs that select this would be capable of 851 # Archs that select this would be capable of PMD-sized vmaps (i.e.,
973 # arch_vmap_pmd_supported() returns true). Th !! 852 # arch_vmap_pmd_supported() returns true), and they must make no assumptions
974 # must be used to enable allocations to use h !! 853 # that vmalloc memory is mapped with PAGE_SIZE ptes. The VM_NO_HUGE_VMAP flag
>> 854 # can be used to prohibit arch-specific allocations from using hugepages to
>> 855 # help with this (e.g., modules may require it).
975 # 856 #
976 config HAVE_ARCH_HUGE_VMALLOC 857 config HAVE_ARCH_HUGE_VMALLOC
977 depends on HAVE_ARCH_HUGE_VMAP 858 depends on HAVE_ARCH_HUGE_VMAP
978 bool 859 bool
979 860
980 config ARCH_WANT_HUGE_PMD_SHARE 861 config ARCH_WANT_HUGE_PMD_SHARE
981 bool 862 bool
982 863
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 864 config HAVE_ARCH_SOFT_DIRTY
992 bool 865 bool
993 866
994 config HAVE_MOD_ARCH_SPECIFIC 867 config HAVE_MOD_ARCH_SPECIFIC
995 bool 868 bool
996 help 869 help
997 The arch uses struct mod_arch_specif 870 The arch uses struct mod_arch_specific to store data. Many arches
998 just need a simple module loader wit 871 just need a simple module loader without arch specific data - those
999 should not enable this. 872 should not enable this.
1000 873
1001 config MODULES_USE_ELF_RELA 874 config MODULES_USE_ELF_RELA
1002 bool 875 bool
1003 help 876 help
1004 Modules only use ELF RELA relocatio 877 Modules only use ELF RELA relocations. Modules with ELF REL
1005 relocations will give an error. 878 relocations will give an error.
1006 879
1007 config MODULES_USE_ELF_REL 880 config MODULES_USE_ELF_REL
1008 bool 881 bool
1009 help 882 help
1010 Modules only use ELF REL relocation 883 Modules only use ELF REL relocations. Modules with ELF RELA
1011 relocations will give an error. 884 relocations will give an error.
1012 885
1013 config ARCH_WANTS_MODULES_DATA_IN_VMALLOC <<
1014 bool <<
1015 help <<
1016 For architectures like powerpc/32 w <<
1017 allocation and need to allocate mod <<
1018 <<
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 886 config HAVE_IRQ_EXIT_ON_IRQ_STACK
1028 bool 887 bool
1029 help 888 help
1030 Architecture doesn't only execute t 889 Architecture doesn't only execute the irq handler on the irq stack
1031 but also irq_exit(). This way we ca 890 but also irq_exit(). This way we can process softirqs on this irq
1032 stack instead of switching to a new 891 stack instead of switching to a new one when we call __do_softirq()
1033 in the end of an hardirq. 892 in the end of an hardirq.
1034 This spares a stack switch and impr 893 This spares a stack switch and improves cache usage on softirq
1035 processing. 894 processing.
1036 895
1037 config HAVE_SOFTIRQ_ON_OWN_STACK 896 config HAVE_SOFTIRQ_ON_OWN_STACK
1038 bool 897 bool
1039 help 898 help
1040 Architecture provides a function to 899 Architecture provides a function to run __do_softirq() on a
1041 separate stack. 900 separate stack.
1042 901
1043 config SOFTIRQ_ON_OWN_STACK <<
1044 def_bool HAVE_SOFTIRQ_ON_OWN_STACK && <<
1045 <<
1046 config ALTERNATE_USER_ADDRESS_SPACE <<
1047 bool <<
1048 help <<
1049 Architectures set this when the CPU <<
1050 spaces for kernel and user space po <<
1051 access_ok() check on a __user point <<
1052 <<
1053 config PGTABLE_LEVELS 902 config PGTABLE_LEVELS
1054 int 903 int
1055 default 2 904 default 2
1056 905
1057 config ARCH_HAS_ELF_RANDOMIZE 906 config ARCH_HAS_ELF_RANDOMIZE
1058 bool 907 bool
1059 help 908 help
1060 An architecture supports choosing r 909 An architecture supports choosing randomized locations for
1061 stack, mmap, brk, and ET_DYN. Defin 910 stack, mmap, brk, and ET_DYN. Defined functions:
1062 - arch_mmap_rnd() 911 - arch_mmap_rnd()
1063 - arch_randomize_brk() 912 - arch_randomize_brk()
1064 913
1065 config HAVE_ARCH_MMAP_RND_BITS 914 config HAVE_ARCH_MMAP_RND_BITS
1066 bool 915 bool
1067 help 916 help
1068 An arch should select this symbol i 917 An arch should select this symbol if it supports setting a variable
1069 number of bits for use in establish 918 number of bits for use in establishing the base address for mmap
1070 allocations, has MMU enabled and pr 919 allocations, has MMU enabled and provides values for both:
1071 - ARCH_MMAP_RND_BITS_MIN 920 - ARCH_MMAP_RND_BITS_MIN
1072 - ARCH_MMAP_RND_BITS_MAX 921 - ARCH_MMAP_RND_BITS_MAX
1073 922
1074 config HAVE_EXIT_THREAD 923 config HAVE_EXIT_THREAD
1075 bool 924 bool
1076 help 925 help
1077 An architecture implements exit_thr 926 An architecture implements exit_thread.
1078 927
1079 config ARCH_MMAP_RND_BITS_MIN 928 config ARCH_MMAP_RND_BITS_MIN
1080 int 929 int
1081 930
1082 config ARCH_MMAP_RND_BITS_MAX 931 config ARCH_MMAP_RND_BITS_MAX
1083 int 932 int
1084 933
1085 config ARCH_MMAP_RND_BITS_DEFAULT 934 config ARCH_MMAP_RND_BITS_DEFAULT
1086 int 935 int
1087 936
1088 config ARCH_MMAP_RND_BITS 937 config ARCH_MMAP_RND_BITS
1089 int "Number of bits to use for ASLR o 938 int "Number of bits to use for ASLR of mmap base address" if EXPERT
1090 range ARCH_MMAP_RND_BITS_MIN ARCH_MMA 939 range ARCH_MMAP_RND_BITS_MIN ARCH_MMAP_RND_BITS_MAX
1091 default ARCH_MMAP_RND_BITS_DEFAULT if 940 default ARCH_MMAP_RND_BITS_DEFAULT if ARCH_MMAP_RND_BITS_DEFAULT
1092 default ARCH_MMAP_RND_BITS_MIN 941 default ARCH_MMAP_RND_BITS_MIN
1093 depends on HAVE_ARCH_MMAP_RND_BITS 942 depends on HAVE_ARCH_MMAP_RND_BITS
1094 help 943 help
1095 This value can be used to select th 944 This value can be used to select the number of bits to use to
1096 determine the random offset to the 945 determine the random offset to the base address of vma regions
1097 resulting from mmap allocations. Th 946 resulting from mmap allocations. This value will be bounded
1098 by the architecture's minimum and m 947 by the architecture's minimum and maximum supported values.
1099 948
1100 This value can be changed after boo 949 This value can be changed after boot using the
1101 /proc/sys/vm/mmap_rnd_bits tunable 950 /proc/sys/vm/mmap_rnd_bits tunable
1102 951
1103 config HAVE_ARCH_MMAP_RND_COMPAT_BITS 952 config HAVE_ARCH_MMAP_RND_COMPAT_BITS
1104 bool 953 bool
1105 help 954 help
1106 An arch should select this symbol i 955 An arch should select this symbol if it supports running applications
1107 in compatibility mode, supports set 956 in compatibility mode, supports setting a variable number of bits for
1108 use in establishing the base addres 957 use in establishing the base address for mmap allocations, has MMU
1109 enabled and provides values for bot 958 enabled and provides values for both:
1110 - ARCH_MMAP_RND_COMPAT_BITS_MIN 959 - ARCH_MMAP_RND_COMPAT_BITS_MIN
1111 - ARCH_MMAP_RND_COMPAT_BITS_MAX 960 - ARCH_MMAP_RND_COMPAT_BITS_MAX
1112 961
1113 config ARCH_MMAP_RND_COMPAT_BITS_MIN 962 config ARCH_MMAP_RND_COMPAT_BITS_MIN
1114 int 963 int
1115 964
1116 config ARCH_MMAP_RND_COMPAT_BITS_MAX 965 config ARCH_MMAP_RND_COMPAT_BITS_MAX
1117 int 966 int
1118 967
1119 config ARCH_MMAP_RND_COMPAT_BITS_DEFAULT 968 config ARCH_MMAP_RND_COMPAT_BITS_DEFAULT
1120 int 969 int
1121 970
1122 config ARCH_MMAP_RND_COMPAT_BITS 971 config ARCH_MMAP_RND_COMPAT_BITS
1123 int "Number of bits to use for ASLR o 972 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 973 range ARCH_MMAP_RND_COMPAT_BITS_MIN ARCH_MMAP_RND_COMPAT_BITS_MAX
1125 default ARCH_MMAP_RND_COMPAT_BITS_DEF 974 default ARCH_MMAP_RND_COMPAT_BITS_DEFAULT if ARCH_MMAP_RND_COMPAT_BITS_DEFAULT
1126 default ARCH_MMAP_RND_COMPAT_BITS_MIN 975 default ARCH_MMAP_RND_COMPAT_BITS_MIN
1127 depends on HAVE_ARCH_MMAP_RND_COMPAT_ 976 depends on HAVE_ARCH_MMAP_RND_COMPAT_BITS
1128 help 977 help
1129 This value can be used to select th 978 This value can be used to select the number of bits to use to
1130 determine the random offset to the 979 determine the random offset to the base address of vma regions
1131 resulting from mmap allocations for 980 resulting from mmap allocations for compatible applications This
1132 value will be bounded by the archit 981 value will be bounded by the architecture's minimum and maximum
1133 supported values. 982 supported values.
1134 983
1135 This value can be changed after boo 984 This value can be changed after boot using the
1136 /proc/sys/vm/mmap_rnd_compat_bits t 985 /proc/sys/vm/mmap_rnd_compat_bits tunable
1137 986
1138 config HAVE_ARCH_COMPAT_MMAP_BASES 987 config HAVE_ARCH_COMPAT_MMAP_BASES
1139 bool 988 bool
1140 help 989 help
1141 This allows 64bit applications to i 990 This allows 64bit applications to invoke 32-bit mmap() syscall
1142 and vice-versa 32-bit applications 991 and vice-versa 32-bit applications to call 64-bit mmap().
1143 Required for applications doing dif 992 Required for applications doing different bitness syscalls.
1144 993
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 994 config PAGE_SIZE_LESS_THAN_64KB
1229 def_bool y 995 def_bool y
>> 996 depends on !ARM64_64K_PAGES
>> 997 depends on !IA64_PAGE_SIZE_64KB
1230 depends on !PAGE_SIZE_64KB 998 depends on !PAGE_SIZE_64KB
1231 depends on PAGE_SIZE_LESS_THAN_256KB !! 999 depends on !PARISC_PAGE_SIZE_64KB
1232 !! 1000 depends on !PPC_64K_PAGES
1233 config PAGE_SIZE_LESS_THAN_256KB !! 1001 depends on !PPC_256K_PAGES
1234 def_bool y <<
1235 depends on !PAGE_SIZE_256KB 1002 depends on !PAGE_SIZE_256KB
1236 1003
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 1004 # This allows to use a set of generic functions to determine mmap base
1247 # address by giving priority to top-down sche 1005 # address by giving priority to top-down scheme only if the process
1248 # is not in legacy mode (compat task, unlimit 1006 # is not in legacy mode (compat task, unlimited stack size or
1249 # sysctl_legacy_va_layout). 1007 # sysctl_legacy_va_layout).
1250 # Architecture that selects this option can p 1008 # Architecture that selects this option can provide its own version of:
1251 # - STACK_RND_MASK 1009 # - STACK_RND_MASK
1252 config ARCH_WANT_DEFAULT_TOPDOWN_MMAP_LAYOUT 1010 config ARCH_WANT_DEFAULT_TOPDOWN_MMAP_LAYOUT
1253 bool 1011 bool
1254 depends on MMU 1012 depends on MMU
1255 select ARCH_HAS_ELF_RANDOMIZE 1013 select ARCH_HAS_ELF_RANDOMIZE
1256 1014
1257 config HAVE_OBJTOOL <<
1258 bool <<
1259 <<
1260 config HAVE_JUMP_LABEL_HACK <<
1261 bool <<
1262 <<
1263 config HAVE_NOINSTR_HACK <<
1264 bool <<
1265 <<
1266 config HAVE_NOINSTR_VALIDATION <<
1267 bool <<
1268 <<
1269 config HAVE_UACCESS_VALIDATION <<
1270 bool <<
1271 select OBJTOOL <<
1272 <<
1273 config HAVE_STACK_VALIDATION 1015 config HAVE_STACK_VALIDATION
1274 bool 1016 bool
1275 help 1017 help
1276 Architecture supports objtool compi !! 1018 Architecture supports the 'objtool check' host tool command, which
1277 validation. !! 1019 performs compile-time stack metadata validation.
1278 1020
1279 config HAVE_RELIABLE_STACKTRACE 1021 config HAVE_RELIABLE_STACKTRACE
1280 bool 1022 bool
1281 help 1023 help
1282 Architecture has either save_stack_ 1024 Architecture has either save_stack_trace_tsk_reliable() or
1283 arch_stack_walk_reliable() function 1025 arch_stack_walk_reliable() function which only returns a stack trace
1284 if it can guarantee the trace is re 1026 if it can guarantee the trace is reliable.
1285 1027
1286 config HAVE_ARCH_HASH 1028 config HAVE_ARCH_HASH
1287 bool 1029 bool
1288 default n 1030 default n
1289 help 1031 help
1290 If this is set, the architecture pr 1032 If this is set, the architecture provides an <asm/hash.h>
1291 file which provides platform-specif 1033 file which provides platform-specific implementations of some
1292 functions in <linux/hash.h> or fs/n 1034 functions in <linux/hash.h> or fs/namei.c.
1293 1035
1294 config HAVE_ARCH_NVRAM_OPS 1036 config HAVE_ARCH_NVRAM_OPS
1295 bool 1037 bool
1296 1038
1297 config ISA_BUS_API 1039 config ISA_BUS_API
1298 def_bool ISA 1040 def_bool ISA
1299 1041
1300 # 1042 #
1301 # ABI hall of shame 1043 # ABI hall of shame
1302 # 1044 #
1303 config CLONE_BACKWARDS 1045 config CLONE_BACKWARDS
1304 bool 1046 bool
1305 help 1047 help
1306 Architecture has tls passed as the 1048 Architecture has tls passed as the 4th argument of clone(2),
1307 not the 5th one. 1049 not the 5th one.
1308 1050
1309 config CLONE_BACKWARDS2 1051 config CLONE_BACKWARDS2
1310 bool 1052 bool
1311 help 1053 help
1312 Architecture has the first two argu 1054 Architecture has the first two arguments of clone(2) swapped.
1313 1055
1314 config CLONE_BACKWARDS3 1056 config CLONE_BACKWARDS3
1315 bool 1057 bool
1316 help 1058 help
1317 Architecture has tls passed as the 1059 Architecture has tls passed as the 3rd argument of clone(2),
1318 not the 5th one. 1060 not the 5th one.
1319 1061
1320 config ODD_RT_SIGACTION 1062 config ODD_RT_SIGACTION
1321 bool 1063 bool
1322 help 1064 help
1323 Architecture has unusual rt_sigacti 1065 Architecture has unusual rt_sigaction(2) arguments
1324 1066
1325 config OLD_SIGSUSPEND 1067 config OLD_SIGSUSPEND
1326 bool 1068 bool
1327 help 1069 help
1328 Architecture has old sigsuspend(2) 1070 Architecture has old sigsuspend(2) syscall, of one-argument variety
1329 1071
1330 config OLD_SIGSUSPEND3 1072 config OLD_SIGSUSPEND3
1331 bool 1073 bool
1332 help 1074 help
1333 Even weirder antique ABI - three-ar 1075 Even weirder antique ABI - three-argument sigsuspend(2)
1334 1076
1335 config OLD_SIGACTION 1077 config OLD_SIGACTION
1336 bool 1078 bool
1337 help 1079 help
1338 Architecture has old sigaction(2) s 1080 Architecture has old sigaction(2) syscall. Nope, not the same
1339 as OLD_SIGSUSPEND | OLD_SIGSUSPEND3 1081 as OLD_SIGSUSPEND | OLD_SIGSUSPEND3 - alpha has sigsuspend(2),
1340 but fairly different variant of sig 1082 but fairly different variant of sigaction(2), thanks to OSF/1
1341 compatibility... 1083 compatibility...
1342 1084
1343 config COMPAT_OLD_SIGACTION 1085 config COMPAT_OLD_SIGACTION
1344 bool 1086 bool
1345 1087
1346 config COMPAT_32BIT_TIME 1088 config COMPAT_32BIT_TIME
1347 bool "Provide system calls for 32-bit 1089 bool "Provide system calls for 32-bit time_t"
1348 default !64BIT || COMPAT 1090 default !64BIT || COMPAT
1349 help 1091 help
1350 This enables 32 bit time_t support 1092 This enables 32 bit time_t support in addition to 64 bit time_t support.
1351 This is relevant on all 32-bit arch 1093 This is relevant on all 32-bit architectures, and 64-bit architectures
1352 as part of compat syscall handling. 1094 as part of compat syscall handling.
1353 1095
1354 config ARCH_NO_PREEMPT 1096 config ARCH_NO_PREEMPT
1355 bool 1097 bool
1356 1098
>> 1099 config ARCH_EPHEMERAL_INODES
>> 1100 def_bool n
>> 1101 help
>> 1102 An arch should select this symbol if it doesn't keep track of inode
>> 1103 instances on its own, but instead relies on something else (e.g. the
>> 1104 host kernel for an UML kernel).
>> 1105
1357 config ARCH_SUPPORTS_RT 1106 config ARCH_SUPPORTS_RT
1358 bool 1107 bool
1359 1108
1360 config CPU_NO_EFFICIENT_FFS 1109 config CPU_NO_EFFICIENT_FFS
1361 def_bool n 1110 def_bool n
1362 1111
1363 config HAVE_ARCH_VMAP_STACK 1112 config HAVE_ARCH_VMAP_STACK
1364 def_bool n 1113 def_bool n
1365 help 1114 help
1366 An arch should select this symbol i 1115 An arch should select this symbol if it can support kernel stacks
1367 in vmalloc space. This means: 1116 in vmalloc space. This means:
1368 1117
1369 - vmalloc space must be large enoug 1118 - vmalloc space must be large enough to hold many kernel stacks.
1370 This may rule out many 32-bit arc 1119 This may rule out many 32-bit architectures.
1371 1120
1372 - Stacks in vmalloc space need to w 1121 - Stacks in vmalloc space need to work reliably. For example, if
1373 vmap page tables are created on d 1122 vmap page tables are created on demand, either this mechanism
1374 needs to work while the stack poi 1123 needs to work while the stack points to a virtual address with
1375 unpopulated page tables or arch c 1124 unpopulated page tables or arch code (switch_to() and switch_mm(),
1376 most likely) needs to ensure that 1125 most likely) needs to ensure that the stack's page table entries
1377 are populated before running on a 1126 are populated before running on a possibly unpopulated stack.
1378 1127
1379 - If the stack overflows into a gua 1128 - If the stack overflows into a guard page, something reasonable
1380 should happen. The definition of 1129 should happen. The definition of "reasonable" is flexible, but
1381 instantly rebooting without loggi 1130 instantly rebooting without logging anything would be unfriendly.
1382 1131
1383 config VMAP_STACK 1132 config VMAP_STACK
1384 default y 1133 default y
1385 bool "Use a virtually-mapped stack" 1134 bool "Use a virtually-mapped stack"
1386 depends on HAVE_ARCH_VMAP_STACK 1135 depends on HAVE_ARCH_VMAP_STACK
1387 depends on !KASAN || KASAN_HW_TAGS || 1136 depends on !KASAN || KASAN_HW_TAGS || KASAN_VMALLOC
1388 help 1137 help
1389 Enable this if you want the use vir 1138 Enable this if you want the use virtually-mapped kernel stacks
1390 with guard pages. This causes kern 1139 with guard pages. This causes kernel stack overflows to be
1391 caught immediately rather than caus 1140 caught immediately rather than causing difficult-to-diagnose
1392 corruption. 1141 corruption.
1393 1142
1394 To use this with software KASAN mod 1143 To use this with software KASAN modes, the architecture must support
1395 backing virtual mappings with real 1144 backing virtual mappings with real shadow memory, and KASAN_VMALLOC
1396 must be enabled. 1145 must be enabled.
1397 1146
1398 config HAVE_ARCH_RANDOMIZE_KSTACK_OFFSET 1147 config HAVE_ARCH_RANDOMIZE_KSTACK_OFFSET
1399 def_bool n 1148 def_bool n
1400 help 1149 help
1401 An arch should select this symbol i 1150 An arch should select this symbol if it can support kernel stack
1402 offset randomization with calls to 1151 offset randomization with calls to add_random_kstack_offset()
1403 during syscall entry and choose_ran 1152 during syscall entry and choose_random_kstack_offset() during
1404 syscall exit. Careful removal of -f 1153 syscall exit. Careful removal of -fstack-protector-strong and
1405 -fstack-protector should also be ap 1154 -fstack-protector should also be applied to the entry code and
1406 closely examined, as the artificial 1155 closely examined, as the artificial stack bump looks like an array
1407 to the compiler, so it will attempt 1156 to the compiler, so it will attempt to add canary checks regardless
1408 of the static branch state. 1157 of the static branch state.
1409 1158
1410 config RANDOMIZE_KSTACK_OFFSET !! 1159 config RANDOMIZE_KSTACK_OFFSET_DEFAULT
1411 bool "Support for randomizing kernel !! 1160 bool "Randomize kernel stack offset on syscall entry"
1412 default y <<
1413 depends on HAVE_ARCH_RANDOMIZE_KSTACK 1161 depends on HAVE_ARCH_RANDOMIZE_KSTACK_OFFSET
1414 depends on INIT_STACK_NONE || !CC_IS_ 1162 depends on INIT_STACK_NONE || !CC_IS_CLANG || CLANG_VERSION >= 140000
1415 help 1163 help
1416 The kernel stack offset can be rand 1164 The kernel stack offset can be randomized (after pt_regs) by
1417 roughly 5 bits of entropy, frustrat 1165 roughly 5 bits of entropy, frustrating memory corruption
1418 attacks that depend on stack addres 1166 attacks that depend on stack address determinism or
1419 cross-syscall address exposures. !! 1167 cross-syscall address exposures. This feature is controlled
1420 !! 1168 by kernel boot param "randomize_kstack_offset=on/off", and this
1421 The feature is controlled via the " !! 1169 config chooses the default boot state.
1422 kernel boot param, and if turned of <<
1423 of static branches (see JUMP_LABEL) <<
1424 <<
1425 If unsure, say Y. <<
1426 <<
1427 config RANDOMIZE_KSTACK_OFFSET_DEFAULT <<
1428 bool "Default state of kernel stack o <<
1429 depends on RANDOMIZE_KSTACK_OFFSET <<
1430 help <<
1431 Kernel stack offset randomization i <<
1432 "randomize_kstack_offset=on/off", a <<
1433 boot state. <<
1434 1170
1435 config ARCH_OPTIONAL_KERNEL_RWX 1171 config ARCH_OPTIONAL_KERNEL_RWX
1436 def_bool n 1172 def_bool n
1437 1173
1438 config ARCH_OPTIONAL_KERNEL_RWX_DEFAULT 1174 config ARCH_OPTIONAL_KERNEL_RWX_DEFAULT
1439 def_bool n 1175 def_bool n
1440 1176
1441 config ARCH_HAS_STRICT_KERNEL_RWX 1177 config ARCH_HAS_STRICT_KERNEL_RWX
1442 def_bool n 1178 def_bool n
1443 1179
1444 config STRICT_KERNEL_RWX 1180 config STRICT_KERNEL_RWX
1445 bool "Make kernel text and rodata rea 1181 bool "Make kernel text and rodata read-only" if ARCH_OPTIONAL_KERNEL_RWX
1446 depends on ARCH_HAS_STRICT_KERNEL_RWX 1182 depends on ARCH_HAS_STRICT_KERNEL_RWX
1447 default !ARCH_OPTIONAL_KERNEL_RWX || 1183 default !ARCH_OPTIONAL_KERNEL_RWX || ARCH_OPTIONAL_KERNEL_RWX_DEFAULT
1448 help 1184 help
1449 If this is set, kernel text and rod 1185 If this is set, kernel text and rodata memory will be made read-only,
1450 and non-text memory will be made no 1186 and non-text memory will be made non-executable. This provides
1451 protection against certain security 1187 protection against certain security exploits (e.g. executing the heap
1452 or modifying text) 1188 or modifying text)
1453 1189
1454 These features are considered stand 1190 These features are considered standard security practice these days.
1455 You should say Y here in almost all 1191 You should say Y here in almost all cases.
1456 1192
1457 config ARCH_HAS_STRICT_MODULE_RWX 1193 config ARCH_HAS_STRICT_MODULE_RWX
1458 def_bool n 1194 def_bool n
1459 1195
1460 config STRICT_MODULE_RWX 1196 config STRICT_MODULE_RWX
1461 bool "Set loadable kernel module data 1197 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 1198 depends on ARCH_HAS_STRICT_MODULE_RWX && MODULES
1463 default !ARCH_OPTIONAL_KERNEL_RWX || 1199 default !ARCH_OPTIONAL_KERNEL_RWX || ARCH_OPTIONAL_KERNEL_RWX_DEFAULT
1464 help 1200 help
1465 If this is set, module text and rod 1201 If this is set, module text and rodata memory will be made read-only,
1466 and non-text memory will be made no 1202 and non-text memory will be made non-executable. This provides
1467 protection against certain security 1203 protection against certain security exploits (e.g. writing to text)
1468 1204
1469 # select if the architecture provides an asm/ 1205 # select if the architecture provides an asm/dma-direct.h header
1470 config ARCH_HAS_PHYS_TO_DMA 1206 config ARCH_HAS_PHYS_TO_DMA
1471 bool 1207 bool
1472 1208
1473 config HAVE_ARCH_COMPILER_H 1209 config HAVE_ARCH_COMPILER_H
1474 bool 1210 bool
1475 help 1211 help
1476 An architecture can select this if 1212 An architecture can select this if it provides an
1477 asm/compiler.h header that should b 1213 asm/compiler.h header that should be included after
1478 linux/compiler-*.h in order to over 1214 linux/compiler-*.h in order to override macro definitions that those
1479 headers generally provide. 1215 headers generally provide.
1480 1216
1481 config HAVE_ARCH_PREL32_RELOCATIONS 1217 config HAVE_ARCH_PREL32_RELOCATIONS
1482 bool 1218 bool
1483 help 1219 help
1484 May be selected by an architecture 1220 May be selected by an architecture if it supports place-relative
1485 32-bit relocations, both in the too 1221 32-bit relocations, both in the toolchain and in the module loader,
1486 in which case relative references c 1222 in which case relative references can be used in special sections
1487 for PCI fixup, initcalls etc which 1223 for PCI fixup, initcalls etc which are only half the size on 64 bit
1488 architectures, and don't require ru 1224 architectures, and don't require runtime relocation on relocatable
1489 kernels. 1225 kernels.
1490 1226
1491 config ARCH_USE_MEMREMAP_PROT 1227 config ARCH_USE_MEMREMAP_PROT
1492 bool 1228 bool
1493 1229
1494 config LOCK_EVENT_COUNTS 1230 config LOCK_EVENT_COUNTS
1495 bool "Locking event counts collection 1231 bool "Locking event counts collection"
1496 depends on DEBUG_FS 1232 depends on DEBUG_FS
1497 help 1233 help
1498 Enable light-weight counting of var 1234 Enable light-weight counting of various locking related events
1499 in the system with minimal performa 1235 in the system with minimal performance impact. This reduces
1500 the chance of application behavior 1236 the chance of application behavior change because of timing
1501 differences. The counts are reporte 1237 differences. The counts are reported via debugfs.
1502 1238
1503 # Select if the architecture has support for 1239 # Select if the architecture has support for applying RELR relocations.
1504 config ARCH_HAS_RELR 1240 config ARCH_HAS_RELR
1505 bool 1241 bool
1506 1242
1507 config RELR 1243 config RELR
1508 bool "Use RELR relocation packing" 1244 bool "Use RELR relocation packing"
1509 depends on ARCH_HAS_RELR && TOOLS_SUP 1245 depends on ARCH_HAS_RELR && TOOLS_SUPPORT_RELR
1510 default y 1246 default y
1511 help 1247 help
1512 Store the kernel's dynamic relocati 1248 Store the kernel's dynamic relocations in the RELR relocation packing
1513 format. Requires a compatible linke 1249 format. Requires a compatible linker (LLD supports this feature), as
1514 well as compatible NM and OBJCOPY u 1250 well as compatible NM and OBJCOPY utilities (llvm-nm and llvm-objcopy
1515 are compatible). 1251 are compatible).
1516 1252
1517 config ARCH_HAS_MEM_ENCRYPT 1253 config ARCH_HAS_MEM_ENCRYPT
1518 bool 1254 bool
1519 1255
1520 config ARCH_HAS_CC_PLATFORM 1256 config ARCH_HAS_CC_PLATFORM
1521 bool 1257 bool
1522 1258
1523 config HAVE_SPARSE_SYSCALL_NR 1259 config HAVE_SPARSE_SYSCALL_NR
1524 bool !! 1260 bool
1525 help !! 1261 help
1526 An architecture should select this !! 1262 An architecture should select this if its syscall numbering is sparse
1527 to save space. For example, MIPS ar 1263 to save space. For example, MIPS architecture has a syscall array with
1528 entries at 4000, 5000 and 6000 loca 1264 entries at 4000, 5000 and 6000 locations. This option turns on syscall
1529 related optimizations for a given a 1265 related optimizations for a given architecture.
1530 1266
1531 config ARCH_HAS_VDSO_DATA 1267 config ARCH_HAS_VDSO_DATA
1532 bool 1268 bool
1533 1269
1534 config HAVE_STATIC_CALL 1270 config HAVE_STATIC_CALL
1535 bool 1271 bool
1536 1272
1537 config HAVE_STATIC_CALL_INLINE 1273 config HAVE_STATIC_CALL_INLINE
1538 bool 1274 bool
1539 depends on HAVE_STATIC_CALL 1275 depends on HAVE_STATIC_CALL
1540 select OBJTOOL <<
1541 1276
1542 config HAVE_PREEMPT_DYNAMIC 1277 config HAVE_PREEMPT_DYNAMIC
1543 bool 1278 bool
1544 <<
1545 config HAVE_PREEMPT_DYNAMIC_CALL <<
1546 bool <<
1547 depends on HAVE_STATIC_CALL 1279 depends on HAVE_STATIC_CALL
1548 select HAVE_PREEMPT_DYNAMIC !! 1280 depends on GENERIC_ENTRY
1549 help <<
1550 An architecture should select this <<
1551 model being selected at boot time u <<
1552 <<
1553 Where an architecture selects HAVE_ <<
1554 preemption function will be patched <<
1555 <<
1556 Where an architecture does not sele <<
1557 call to a preemption function will <<
1558 trampoline will be patched. <<
1559 <<
1560 It is strongly advised to support i <<
1561 overhead. <<
1562 <<
1563 config HAVE_PREEMPT_DYNAMIC_KEY <<
1564 bool <<
1565 depends on HAVE_ARCH_JUMP_LABEL <<
1566 select HAVE_PREEMPT_DYNAMIC <<
1567 help 1281 help
1568 An architecture should select this !! 1282 Select this if the architecture support boot time preempt setting
1569 model being selected at boot time u !! 1283 on top of static calls. It is strongly advised to support inline
1570 !! 1284 static call to avoid any overhead.
1571 Each preemption function will be gi <<
1572 static key. This should have slight <<
1573 static calls, as this effectively i <<
1574 start of its callee. This may avoid <<
1575 integrate better with CFI schemes. <<
1576 <<
1577 This will have greater overhead tha <<
1578 the call to the preemption function <<
1579 1285
1580 config ARCH_WANT_LD_ORPHAN_WARN 1286 config ARCH_WANT_LD_ORPHAN_WARN
1581 bool 1287 bool
1582 help 1288 help
1583 An arch should select this symbol o 1289 An arch should select this symbol once all linker sections are explicitly
1584 included, size-asserted, or discard 1290 included, size-asserted, or discarded in the linker scripts. This is
1585 important because we never want exp 1291 important because we never want expected sections to be placed heuristically
1586 by the linker, since the locations 1292 by the linker, since the locations of such sections can change between linker
1587 versions. 1293 versions.
1588 1294
1589 config HAVE_ARCH_PFN_VALID 1295 config HAVE_ARCH_PFN_VALID
1590 bool 1296 bool
1591 1297
1592 config ARCH_SUPPORTS_DEBUG_PAGEALLOC 1298 config ARCH_SUPPORTS_DEBUG_PAGEALLOC
1593 bool 1299 bool
1594 1300
1595 config ARCH_SUPPORTS_PAGE_TABLE_CHECK <<
1596 bool <<
1597 <<
1598 config ARCH_SPLIT_ARG64 1301 config ARCH_SPLIT_ARG64
1599 bool 1302 bool
1600 help 1303 help
1601 If a 32-bit architecture requires 6 !! 1304 If a 32-bit architecture requires 64-bit arguments to be split into
1602 pairs of 32-bit arguments, select t !! 1305 pairs of 32-bit arguments, select this option.
1603 1306
1604 config ARCH_HAS_ELFCORE_COMPAT 1307 config ARCH_HAS_ELFCORE_COMPAT
1605 bool 1308 bool
1606 1309
1607 config ARCH_HAS_PARANOID_L1D_FLUSH 1310 config ARCH_HAS_PARANOID_L1D_FLUSH
1608 bool 1311 bool
1609 1312
1610 config ARCH_HAVE_TRACE_MMIO_ACCESS <<
1611 bool <<
1612 <<
1613 config DYNAMIC_SIGFRAME 1313 config DYNAMIC_SIGFRAME
1614 bool 1314 bool
1615 1315
1616 # Select, if arch has a named attribute group <<
1617 config HAVE_ARCH_NODE_DEV_GROUP <<
1618 bool <<
1619 <<
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" 1316 source "kernel/gcov/Kconfig"
1643 1317
1644 source "scripts/gcc-plugins/Kconfig" 1318 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 1319
1685 endmenu 1320 endmenu
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