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 # 20 #
21 # Selected by architectures that need custom D 21 # Selected by architectures that need custom DMA operations for e.g. legacy
22 # IOMMUs not handled by dma-iommu. Drivers mu 22 # IOMMUs not handled by dma-iommu. Drivers must never select this symbol.
23 # 23 #
24 config ARCH_HAS_DMA_OPS 24 config ARCH_HAS_DMA_OPS
25 depends on HAS_DMA 25 depends on HAS_DMA
26 select DMA_OPS_HELPERS 26 select DMA_OPS_HELPERS
27 bool 27 bool
28 28
29 menu "General architecture-dependent options" 29 menu "General architecture-dependent options"
30 30
31 config ARCH_HAS_SUBPAGE_FAULTS 31 config ARCH_HAS_SUBPAGE_FAULTS
32 bool 32 bool
33 help 33 help
34 Select if the architecture can check 34 Select if the architecture can check permissions at sub-page
35 granularity (e.g. arm64 MTE). The pr 35 granularity (e.g. arm64 MTE). The probe_user_*() functions
36 must be implemented. 36 must be implemented.
37 37
38 config HOTPLUG_SMT 38 config HOTPLUG_SMT
39 bool 39 bool
40 40
41 config SMT_NUM_THREADS_DYNAMIC 41 config SMT_NUM_THREADS_DYNAMIC
42 bool 42 bool
43 43
44 # Selected by HOTPLUG_CORE_SYNC_DEAD or HOTPLU 44 # Selected by HOTPLUG_CORE_SYNC_DEAD or HOTPLUG_CORE_SYNC_FULL
45 config HOTPLUG_CORE_SYNC 45 config HOTPLUG_CORE_SYNC
46 bool 46 bool
47 47
48 # Basic CPU dead synchronization selected by a 48 # Basic CPU dead synchronization selected by architecture
49 config HOTPLUG_CORE_SYNC_DEAD 49 config HOTPLUG_CORE_SYNC_DEAD
50 bool 50 bool
51 select HOTPLUG_CORE_SYNC 51 select HOTPLUG_CORE_SYNC
52 52
53 # Full CPU synchronization with alive state se 53 # Full CPU synchronization with alive state selected by architecture
54 config HOTPLUG_CORE_SYNC_FULL 54 config HOTPLUG_CORE_SYNC_FULL
55 bool 55 bool
56 select HOTPLUG_CORE_SYNC_DEAD if HOTPL 56 select HOTPLUG_CORE_SYNC_DEAD if HOTPLUG_CPU
57 select HOTPLUG_CORE_SYNC 57 select HOTPLUG_CORE_SYNC
58 58
59 config HOTPLUG_SPLIT_STARTUP 59 config HOTPLUG_SPLIT_STARTUP
60 bool 60 bool
61 select HOTPLUG_CORE_SYNC_FULL 61 select HOTPLUG_CORE_SYNC_FULL
62 62
63 config HOTPLUG_PARALLEL 63 config HOTPLUG_PARALLEL
64 bool 64 bool
65 select HOTPLUG_SPLIT_STARTUP 65 select HOTPLUG_SPLIT_STARTUP
66 66
67 config GENERIC_ENTRY 67 config GENERIC_ENTRY
68 bool 68 bool
69 69
70 config KPROBES 70 config KPROBES
71 bool "Kprobes" 71 bool "Kprobes"
72 depends on HAVE_KPROBES 72 depends on HAVE_KPROBES
73 select KALLSYMS 73 select KALLSYMS
74 select EXECMEM 74 select EXECMEM
75 select NEED_TASKS_RCU 75 select NEED_TASKS_RCU
76 help 76 help
77 Kprobes allows you to trap at almost 77 Kprobes allows you to trap at almost any kernel address and
78 execute a callback function. regist 78 execute a callback function. register_kprobe() establishes
79 a probepoint and specifies the callb 79 a probepoint and specifies the callback. Kprobes is useful
80 for kernel debugging, non-intrusive 80 for kernel debugging, non-intrusive instrumentation and testing.
81 If in doubt, say "N". 81 If in doubt, say "N".
82 82
83 config JUMP_LABEL 83 config JUMP_LABEL
84 bool "Optimize very unlikely/likely br 84 bool "Optimize very unlikely/likely branches"
85 depends on HAVE_ARCH_JUMP_LABEL 85 depends on HAVE_ARCH_JUMP_LABEL
86 select OBJTOOL if HAVE_JUMP_LABEL_HACK 86 select OBJTOOL if HAVE_JUMP_LABEL_HACK
87 help 87 help
88 This option enables a transparent br 88 This option enables a transparent branch optimization that
89 makes certain almost-always-true or 89 makes certain almost-always-true or almost-always-false branch
90 conditions even cheaper to execute w 90 conditions even cheaper to execute within the kernel.
91 91
92 Certain performance-sensitive kernel 92 Certain performance-sensitive kernel code, such as trace points,
93 scheduler functionality, networking 93 scheduler functionality, networking code and KVM have such
94 branches and include support for thi 94 branches and include support for this optimization technique.
95 95
96 If it is detected that the compiler 96 If it is detected that the compiler has support for "asm goto",
97 the kernel will compile such branche 97 the kernel will compile such branches with just a nop
98 instruction. When the condition flag 98 instruction. When the condition flag is toggled to true, the
99 nop will be converted to a jump inst 99 nop will be converted to a jump instruction to execute the
100 conditional block of instructions. 100 conditional block of instructions.
101 101
102 This technique lowers overhead and s 102 This technique lowers overhead and stress on the branch prediction
103 of the processor and generally makes 103 of the processor and generally makes the kernel faster. The update
104 of the condition is slower, but thos 104 of the condition is slower, but those are always very rare.
105 105
106 ( On 32-bit x86, the necessary optio 106 ( On 32-bit x86, the necessary options added to the compiler
107 flags may increase the size of the 107 flags may increase the size of the kernel slightly. )
108 108
109 config STATIC_KEYS_SELFTEST 109 config STATIC_KEYS_SELFTEST
110 bool "Static key selftest" 110 bool "Static key selftest"
111 depends on JUMP_LABEL 111 depends on JUMP_LABEL
112 help 112 help
113 Boot time self-test of the branch pa 113 Boot time self-test of the branch patching code.
114 114
115 config STATIC_CALL_SELFTEST 115 config STATIC_CALL_SELFTEST
116 bool "Static call selftest" 116 bool "Static call selftest"
117 depends on HAVE_STATIC_CALL 117 depends on HAVE_STATIC_CALL
118 help 118 help
119 Boot time self-test of the call patc 119 Boot time self-test of the call patching code.
120 120
121 config OPTPROBES 121 config OPTPROBES
122 def_bool y 122 def_bool y
123 depends on KPROBES && HAVE_OPTPROBES 123 depends on KPROBES && HAVE_OPTPROBES
124 select NEED_TASKS_RCU 124 select NEED_TASKS_RCU
125 125
126 config KPROBES_ON_FTRACE 126 config KPROBES_ON_FTRACE
127 def_bool y 127 def_bool y
128 depends on KPROBES && HAVE_KPROBES_ON_ 128 depends on KPROBES && HAVE_KPROBES_ON_FTRACE
129 depends on DYNAMIC_FTRACE_WITH_REGS 129 depends on DYNAMIC_FTRACE_WITH_REGS
130 help 130 help
131 If function tracer is enabled and th 131 If function tracer is enabled and the arch supports full
132 passing of pt_regs to function traci 132 passing of pt_regs to function tracing, then kprobes can
133 optimize on top of function tracing. 133 optimize on top of function tracing.
134 134
135 config UPROBES 135 config UPROBES
136 def_bool n 136 def_bool n
137 depends on ARCH_SUPPORTS_UPROBES 137 depends on ARCH_SUPPORTS_UPROBES
138 help 138 help
139 Uprobes is the user-space counterpar 139 Uprobes is the user-space counterpart to kprobes: they
140 enable instrumentation applications 140 enable instrumentation applications (such as 'perf probe')
141 to establish unintrusive probes in u 141 to establish unintrusive probes in user-space binaries and
142 libraries, by executing handler func 142 libraries, by executing handler functions when the probes
143 are hit by user-space applications. 143 are hit by user-space applications.
144 144
145 ( These probes come in the form of s 145 ( These probes come in the form of single-byte breakpoints,
146 managed by the kernel and kept tra 146 managed by the kernel and kept transparent to the probed
147 application. ) 147 application. )
148 148
149 config HAVE_64BIT_ALIGNED_ACCESS 149 config HAVE_64BIT_ALIGNED_ACCESS
150 def_bool 64BIT && !HAVE_EFFICIENT_UNAL 150 def_bool 64BIT && !HAVE_EFFICIENT_UNALIGNED_ACCESS
151 help 151 help
152 Some architectures require 64 bit ac 152 Some architectures require 64 bit accesses to be 64 bit
153 aligned, which also requires structs 153 aligned, which also requires structs containing 64 bit values
154 to be 64 bit aligned too. This inclu 154 to be 64 bit aligned too. This includes some 32 bit
155 architectures which can do 64 bit ac 155 architectures which can do 64 bit accesses, as well as 64 bit
156 architectures without unaligned acce 156 architectures without unaligned access.
157 157
158 This symbol should be selected by an 158 This symbol should be selected by an architecture if 64 bit
159 accesses are required to be 64 bit a 159 accesses are required to be 64 bit aligned in this way even
160 though it is not a 64 bit architectu 160 though it is not a 64 bit architecture.
161 161
162 See Documentation/core-api/unaligned 162 See Documentation/core-api/unaligned-memory-access.rst for
163 more information on the topic of una 163 more information on the topic of unaligned memory accesses.
164 164
165 config HAVE_EFFICIENT_UNALIGNED_ACCESS 165 config HAVE_EFFICIENT_UNALIGNED_ACCESS
166 bool 166 bool
167 help 167 help
168 Some architectures are unable to per 168 Some architectures are unable to perform unaligned accesses
169 without the use of get_unaligned/put 169 without the use of get_unaligned/put_unaligned. Others are
170 unable to perform such accesses effi 170 unable to perform such accesses efficiently (e.g. trap on
171 unaligned access and require fixing 171 unaligned access and require fixing it up in the exception
172 handler.) 172 handler.)
173 173
174 This symbol should be selected by an 174 This symbol should be selected by an architecture if it can
175 perform unaligned accesses efficient 175 perform unaligned accesses efficiently to allow different
176 code paths to be selected for these 176 code paths to be selected for these cases. Some network
177 drivers, for example, could opt to n 177 drivers, for example, could opt to not fix up alignment
178 problems with received packets if do 178 problems with received packets if doing so would not help
179 much. 179 much.
180 180
181 See Documentation/core-api/unaligned 181 See Documentation/core-api/unaligned-memory-access.rst for more
182 information on the topic of unaligne 182 information on the topic of unaligned memory accesses.
183 183
184 config ARCH_USE_BUILTIN_BSWAP 184 config ARCH_USE_BUILTIN_BSWAP
185 bool 185 bool
186 help 186 help
187 Modern versions of GCC (since 4.4) h 187 Modern versions of GCC (since 4.4) have builtin functions
188 for handling byte-swapping. Using th 188 for handling byte-swapping. Using these, instead of the old
189 inline assembler that the architectu 189 inline assembler that the architecture code provides in the
190 __arch_bswapXX() macros, allows the 190 __arch_bswapXX() macros, allows the compiler to see what's
191 happening and offers more opportunit 191 happening and offers more opportunity for optimisation. In
192 particular, the compiler will be abl 192 particular, the compiler will be able to combine the byteswap
193 with a nearby load or store and use 193 with a nearby load or store and use load-and-swap or
194 store-and-swap instructions if the a 194 store-and-swap instructions if the architecture has them. It
195 should almost *never* result in code 195 should almost *never* result in code which is worse than the
196 hand-coded assembler in <asm/swab.h> 196 hand-coded assembler in <asm/swab.h>. But just in case it
197 does, the use of the builtins is opt 197 does, the use of the builtins is optional.
198 198
199 Any architecture with load-and-swap 199 Any architecture with load-and-swap or store-and-swap
200 instructions should set this. And it 200 instructions should set this. And it shouldn't hurt to set it
201 on architectures that don't have suc 201 on architectures that don't have such instructions.
202 202
203 config KRETPROBES 203 config KRETPROBES
204 def_bool y 204 def_bool y
205 depends on KPROBES && (HAVE_KRETPROBES 205 depends on KPROBES && (HAVE_KRETPROBES || HAVE_RETHOOK)
206 206
207 config KRETPROBE_ON_RETHOOK 207 config KRETPROBE_ON_RETHOOK
208 def_bool y 208 def_bool y
209 depends on HAVE_RETHOOK 209 depends on HAVE_RETHOOK
210 depends on KRETPROBES 210 depends on KRETPROBES
211 select RETHOOK 211 select RETHOOK
212 212
213 config USER_RETURN_NOTIFIER 213 config USER_RETURN_NOTIFIER
214 bool 214 bool
215 depends on HAVE_USER_RETURN_NOTIFIER 215 depends on HAVE_USER_RETURN_NOTIFIER
216 help 216 help
217 Provide a kernel-internal notificati 217 Provide a kernel-internal notification when a cpu is about to
218 switch to user mode. 218 switch to user mode.
219 219
220 config HAVE_IOREMAP_PROT 220 config HAVE_IOREMAP_PROT
221 bool 221 bool
222 222
223 config HAVE_KPROBES 223 config HAVE_KPROBES
224 bool 224 bool
225 225
226 config HAVE_KRETPROBES 226 config HAVE_KRETPROBES
227 bool 227 bool
228 228
229 config HAVE_OPTPROBES 229 config HAVE_OPTPROBES
230 bool 230 bool
231 231
232 config HAVE_KPROBES_ON_FTRACE 232 config HAVE_KPROBES_ON_FTRACE
233 bool 233 bool
234 234
235 config ARCH_CORRECT_STACKTRACE_ON_KRETPROBE 235 config ARCH_CORRECT_STACKTRACE_ON_KRETPROBE
236 bool 236 bool
237 help 237 help
238 Since kretprobes modifies return add 238 Since kretprobes modifies return address on the stack, the
239 stacktrace may see the kretprobe tra 239 stacktrace may see the kretprobe trampoline address instead
240 of correct one. If the architecture 240 of correct one. If the architecture stacktrace code and
241 unwinder can adjust such entries, se 241 unwinder can adjust such entries, select this configuration.
242 242
243 config HAVE_FUNCTION_ERROR_INJECTION 243 config HAVE_FUNCTION_ERROR_INJECTION
244 bool 244 bool
245 245
246 config HAVE_NMI 246 config HAVE_NMI
247 bool 247 bool
248 248
249 config HAVE_FUNCTION_DESCRIPTORS 249 config HAVE_FUNCTION_DESCRIPTORS
250 bool 250 bool
251 251
252 config TRACE_IRQFLAGS_SUPPORT 252 config TRACE_IRQFLAGS_SUPPORT
253 bool 253 bool
254 254
255 config TRACE_IRQFLAGS_NMI_SUPPORT 255 config TRACE_IRQFLAGS_NMI_SUPPORT
256 bool 256 bool
257 257
258 # 258 #
259 # An arch should select this if it provides al 259 # An arch should select this if it provides all these things:
260 # 260 #
261 # task_pt_regs() in asm/process 261 # task_pt_regs() in asm/processor.h or asm/ptrace.h
262 # arch_has_single_step() if there is ha 262 # arch_has_single_step() if there is hardware single-step support
263 # arch_has_block_step() if there is ha 263 # arch_has_block_step() if there is hardware block-step support
264 # asm/syscall.h supplying asm- 264 # asm/syscall.h supplying asm-generic/syscall.h interface
265 # linux/regset.h user_regset in 265 # linux/regset.h user_regset interfaces
266 # CORE_DUMP_USE_REGSET #define'd in l 266 # CORE_DUMP_USE_REGSET #define'd in linux/elf.h
267 # TIF_SYSCALL_TRACE calls ptrace_r 267 # TIF_SYSCALL_TRACE calls ptrace_report_syscall_{entry,exit}
268 # TIF_NOTIFY_RESUME calls resume_u 268 # TIF_NOTIFY_RESUME calls resume_user_mode_work()
269 # 269 #
270 config HAVE_ARCH_TRACEHOOK 270 config HAVE_ARCH_TRACEHOOK
271 bool 271 bool
272 272
273 config HAVE_DMA_CONTIGUOUS 273 config HAVE_DMA_CONTIGUOUS
274 bool 274 bool
275 275
276 config GENERIC_SMP_IDLE_THREAD 276 config GENERIC_SMP_IDLE_THREAD
277 bool 277 bool
278 278
279 config GENERIC_IDLE_POLL_SETUP 279 config GENERIC_IDLE_POLL_SETUP
280 bool 280 bool
281 281
282 config ARCH_HAS_FORTIFY_SOURCE 282 config ARCH_HAS_FORTIFY_SOURCE
283 bool 283 bool
284 help 284 help
285 An architecture should select this w 285 An architecture should select this when it can successfully
286 build and run with CONFIG_FORTIFY_SO 286 build and run with CONFIG_FORTIFY_SOURCE.
287 287
288 # 288 #
289 # Select if the arch provides a historic keepi 289 # Select if the arch provides a historic keepinit alias for the retain_initrd
290 # command line option 290 # command line option
291 # 291 #
292 config ARCH_HAS_KEEPINITRD 292 config ARCH_HAS_KEEPINITRD
293 bool 293 bool
294 294
295 # Select if arch has all set_memory_ro/rw/x/nx 295 # Select if arch has all set_memory_ro/rw/x/nx() functions in asm/cacheflush.h
296 config ARCH_HAS_SET_MEMORY 296 config ARCH_HAS_SET_MEMORY
297 bool 297 bool
298 298
299 # Select if arch has all set_direct_map_invali 299 # Select if arch has all set_direct_map_invalid/default() functions
300 config ARCH_HAS_SET_DIRECT_MAP 300 config ARCH_HAS_SET_DIRECT_MAP
301 bool 301 bool
302 302
303 # 303 #
304 # Select if the architecture provides the arch 304 # Select if the architecture provides the arch_dma_set_uncached symbol to
305 # either provide an uncached segment alias for 305 # either provide an uncached segment alias for a DMA allocation, or
306 # to remap the page tables in place. 306 # to remap the page tables in place.
307 # 307 #
308 config ARCH_HAS_DMA_SET_UNCACHED 308 config ARCH_HAS_DMA_SET_UNCACHED
309 bool 309 bool
310 310
311 # 311 #
312 # Select if the architectures provides the arc 312 # Select if the architectures provides the arch_dma_clear_uncached symbol
313 # to undo an in-place page table remap for unc 313 # to undo an in-place page table remap for uncached access.
314 # 314 #
315 config ARCH_HAS_DMA_CLEAR_UNCACHED 315 config ARCH_HAS_DMA_CLEAR_UNCACHED
316 bool 316 bool
317 317
318 config ARCH_HAS_CPU_FINALIZE_INIT 318 config ARCH_HAS_CPU_FINALIZE_INIT
319 bool 319 bool
320 320
321 # The architecture has a per-task state that i 321 # The architecture has a per-task state that includes the mm's PASID
322 config ARCH_HAS_CPU_PASID 322 config ARCH_HAS_CPU_PASID
323 bool 323 bool
324 select IOMMU_MM_DATA 324 select IOMMU_MM_DATA
325 325
326 config HAVE_ARCH_THREAD_STRUCT_WHITELIST 326 config HAVE_ARCH_THREAD_STRUCT_WHITELIST
327 bool 327 bool
328 help 328 help
329 An architecture should select this t 329 An architecture should select this to provide hardened usercopy
330 knowledge about what region of the t 330 knowledge about what region of the thread_struct should be
331 whitelisted for copying to userspace 331 whitelisted for copying to userspace. Normally this is only the
332 FPU registers. Specifically, arch_th 332 FPU registers. Specifically, arch_thread_struct_whitelist()
333 should be implemented. Without this, 333 should be implemented. Without this, the entire thread_struct
334 field in task_struct will be left wh 334 field in task_struct will be left whitelisted.
335 335
336 # Select if arch wants to size task_struct dyn 336 # Select if arch wants to size task_struct dynamically via arch_task_struct_size:
337 config ARCH_WANTS_DYNAMIC_TASK_STRUCT 337 config ARCH_WANTS_DYNAMIC_TASK_STRUCT
338 bool 338 bool
339 339
340 config ARCH_WANTS_NO_INSTR 340 config ARCH_WANTS_NO_INSTR
341 bool 341 bool
342 help 342 help
343 An architecture should select this i 343 An architecture should select this if the noinstr macro is being used on
344 functions to denote that the toolcha 344 functions to denote that the toolchain should avoid instrumenting such
345 functions and is required for correc 345 functions and is required for correctness.
346 346
347 config ARCH_32BIT_OFF_T 347 config ARCH_32BIT_OFF_T
348 bool 348 bool
349 depends on !64BIT 349 depends on !64BIT
350 help 350 help
351 All new 32-bit architectures should 351 All new 32-bit architectures should have 64-bit off_t type on
352 userspace side which corresponds to 352 userspace side which corresponds to the loff_t kernel type. This
353 is the requirement for modern ABIs. 353 is the requirement for modern ABIs. Some existing architectures
354 still support 32-bit off_t. This opt 354 still support 32-bit off_t. This option is enabled for all such
355 architectures explicitly. 355 architectures explicitly.
356 356
357 # Selected by 64 bit architectures which have 357 # Selected by 64 bit architectures which have a 32 bit f_tinode in struct ustat
358 config ARCH_32BIT_USTAT_F_TINODE 358 config ARCH_32BIT_USTAT_F_TINODE
359 bool 359 bool
360 360
361 config HAVE_ASM_MODVERSIONS 361 config HAVE_ASM_MODVERSIONS
362 bool 362 bool
363 help 363 help
364 This symbol should be selected by an 364 This symbol should be selected by an architecture if it provides
365 <asm/asm-prototypes.h> to support th 365 <asm/asm-prototypes.h> to support the module versioning for symbols
366 exported from assembly code. 366 exported from assembly code.
367 367
368 config HAVE_REGS_AND_STACK_ACCESS_API 368 config HAVE_REGS_AND_STACK_ACCESS_API
369 bool 369 bool
370 help 370 help
371 This symbol should be selected by an 371 This symbol should be selected by an architecture if it supports
372 the API needed to access registers a 372 the API needed to access registers and stack entries from pt_regs,
373 declared in asm/ptrace.h 373 declared in asm/ptrace.h
374 For example the kprobes-based event 374 For example the kprobes-based event tracer needs this API.
375 375
376 config HAVE_RSEQ 376 config HAVE_RSEQ
377 bool 377 bool
378 depends on HAVE_REGS_AND_STACK_ACCESS_ 378 depends on HAVE_REGS_AND_STACK_ACCESS_API
379 help 379 help
380 This symbol should be selected by an 380 This symbol should be selected by an architecture if it
381 supports an implementation of restar 381 supports an implementation of restartable sequences.
382 382
383 config HAVE_RUST 383 config HAVE_RUST
384 bool 384 bool
385 help 385 help
386 This symbol should be selected by an 386 This symbol should be selected by an architecture if it
387 supports Rust. 387 supports Rust.
388 388
389 config HAVE_FUNCTION_ARG_ACCESS_API 389 config HAVE_FUNCTION_ARG_ACCESS_API
390 bool 390 bool
391 help 391 help
392 This symbol should be selected by an 392 This symbol should be selected by an architecture if it supports
393 the API needed to access function ar 393 the API needed to access function arguments from pt_regs,
394 declared in asm/ptrace.h 394 declared in asm/ptrace.h
395 395
396 config HAVE_HW_BREAKPOINT 396 config HAVE_HW_BREAKPOINT
397 bool 397 bool
398 depends on PERF_EVENTS 398 depends on PERF_EVENTS
399 399
400 config HAVE_MIXED_BREAKPOINTS_REGS 400 config HAVE_MIXED_BREAKPOINTS_REGS
401 bool 401 bool
402 depends on HAVE_HW_BREAKPOINT 402 depends on HAVE_HW_BREAKPOINT
403 help 403 help
404 Depending on the arch implementation 404 Depending on the arch implementation of hardware breakpoints,
405 some of them have separate registers 405 some of them have separate registers for data and instruction
406 breakpoints addresses, others have m 406 breakpoints addresses, others have mixed registers to store
407 them but define the access type in a 407 them but define the access type in a control register.
408 Select this option if your arch impl 408 Select this option if your arch implements breakpoints under the
409 latter fashion. 409 latter fashion.
410 410
411 config HAVE_USER_RETURN_NOTIFIER 411 config HAVE_USER_RETURN_NOTIFIER
412 bool 412 bool
413 413
414 config HAVE_PERF_EVENTS_NMI 414 config HAVE_PERF_EVENTS_NMI
415 bool 415 bool
416 help 416 help
417 System hardware can generate an NMI 417 System hardware can generate an NMI using the perf event
418 subsystem. Also has support for cal 418 subsystem. Also has support for calculating CPU cycle events
419 to determine how many clock cycles i 419 to determine how many clock cycles in a given period.
420 420
421 config HAVE_HARDLOCKUP_DETECTOR_PERF 421 config HAVE_HARDLOCKUP_DETECTOR_PERF
422 bool 422 bool
423 depends on HAVE_PERF_EVENTS_NMI 423 depends on HAVE_PERF_EVENTS_NMI
424 help 424 help
425 The arch chooses to use the generic 425 The arch chooses to use the generic perf-NMI-based hardlockup
426 detector. Must define HAVE_PERF_EVEN 426 detector. Must define HAVE_PERF_EVENTS_NMI.
427 427
428 config HAVE_HARDLOCKUP_DETECTOR_ARCH 428 config HAVE_HARDLOCKUP_DETECTOR_ARCH
429 bool 429 bool
430 help 430 help
431 The arch provides its own hardlockup 431 The arch provides its own hardlockup detector implementation instead
432 of the generic ones. 432 of the generic ones.
433 433
434 It uses the same command line parame 434 It uses the same command line parameters, and sysctl interface,
435 as the generic hardlockup detectors. 435 as the generic hardlockup detectors.
436 436
437 config HAVE_PERF_REGS 437 config HAVE_PERF_REGS
438 bool 438 bool
439 help 439 help
440 Support selective register dumps for 440 Support selective register dumps for perf events. This includes
441 bit-mapping of each registers and a 441 bit-mapping of each registers and a unique architecture id.
442 442
443 config HAVE_PERF_USER_STACK_DUMP 443 config HAVE_PERF_USER_STACK_DUMP
444 bool 444 bool
445 help 445 help
446 Support user stack dumps for perf ev 446 Support user stack dumps for perf event samples. This needs
447 access to the user stack pointer whi 447 access to the user stack pointer which is not unified across
448 architectures. 448 architectures.
449 449
450 config HAVE_ARCH_JUMP_LABEL 450 config HAVE_ARCH_JUMP_LABEL
451 bool 451 bool
452 452
453 config HAVE_ARCH_JUMP_LABEL_RELATIVE 453 config HAVE_ARCH_JUMP_LABEL_RELATIVE
454 bool 454 bool
455 455
456 config MMU_GATHER_TABLE_FREE 456 config MMU_GATHER_TABLE_FREE
457 bool 457 bool
458 458
459 config MMU_GATHER_RCU_TABLE_FREE 459 config MMU_GATHER_RCU_TABLE_FREE
460 bool 460 bool
461 select MMU_GATHER_TABLE_FREE 461 select MMU_GATHER_TABLE_FREE
462 462
463 config MMU_GATHER_PAGE_SIZE 463 config MMU_GATHER_PAGE_SIZE
464 bool 464 bool
465 465
466 config MMU_GATHER_NO_RANGE 466 config MMU_GATHER_NO_RANGE
467 bool 467 bool
468 select MMU_GATHER_MERGE_VMAS 468 select MMU_GATHER_MERGE_VMAS
469 469
470 config MMU_GATHER_NO_FLUSH_CACHE 470 config MMU_GATHER_NO_FLUSH_CACHE
471 bool 471 bool
472 472
473 config MMU_GATHER_MERGE_VMAS 473 config MMU_GATHER_MERGE_VMAS
474 bool 474 bool
475 475
476 config MMU_GATHER_NO_GATHER 476 config MMU_GATHER_NO_GATHER
477 bool 477 bool
478 depends on MMU_GATHER_TABLE_FREE 478 depends on MMU_GATHER_TABLE_FREE
479 479
480 config ARCH_WANT_IRQS_OFF_ACTIVATE_MM 480 config ARCH_WANT_IRQS_OFF_ACTIVATE_MM
481 bool 481 bool
482 help 482 help
483 Temporary select until all architect 483 Temporary select until all architectures can be converted to have
484 irqs disabled over activate_mm. Arch 484 irqs disabled over activate_mm. Architectures that do IPI based TLB
485 shootdowns should enable this. 485 shootdowns should enable this.
486 486
487 # Use normal mm refcounting for MMU_LAZY_TLB k 487 # Use normal mm refcounting for MMU_LAZY_TLB kernel thread references.
488 # MMU_LAZY_TLB_REFCOUNT=n can improve the scal 488 # MMU_LAZY_TLB_REFCOUNT=n can improve the scalability of context switching
489 # to/from kernel threads when the same mm is r 489 # to/from kernel threads when the same mm is running on a lot of CPUs (a large
490 # multi-threaded application), by reducing con 490 # multi-threaded application), by reducing contention on the mm refcount.
491 # 491 #
492 # This can be disabled if the architecture ens 492 # This can be disabled if the architecture ensures no CPUs are using an mm as a
493 # "lazy tlb" beyond its final refcount (i.e., 493 # "lazy tlb" beyond its final refcount (i.e., by the time __mmdrop frees the mm
494 # or its kernel page tables). This could be ar 494 # or its kernel page tables). This could be arranged by arch_exit_mmap(), or
495 # final exit(2) TLB flush, for example. 495 # final exit(2) TLB flush, for example.
496 # 496 #
497 # To implement this, an arch *must*: 497 # To implement this, an arch *must*:
498 # Ensure the _lazy_tlb variants of mmgrab/mmdr 498 # Ensure the _lazy_tlb variants of mmgrab/mmdrop are used when manipulating
499 # the lazy tlb reference of a kthread's ->acti 499 # the lazy tlb reference of a kthread's ->active_mm (non-arch code has been
500 # converted already). 500 # converted already).
501 config MMU_LAZY_TLB_REFCOUNT 501 config MMU_LAZY_TLB_REFCOUNT
502 def_bool y 502 def_bool y
503 depends on !MMU_LAZY_TLB_SHOOTDOWN 503 depends on !MMU_LAZY_TLB_SHOOTDOWN
504 504
505 # This option allows MMU_LAZY_TLB_REFCOUNT=n. 505 # This option allows MMU_LAZY_TLB_REFCOUNT=n. It ensures no CPUs are using an
506 # mm as a lazy tlb beyond its last reference c 506 # mm as a lazy tlb beyond its last reference count, by shooting down these
507 # users before the mm is deallocated. __mmdrop 507 # users before the mm is deallocated. __mmdrop() first IPIs all CPUs that may
508 # be using the mm as a lazy tlb, so that they 508 # be using the mm as a lazy tlb, so that they may switch themselves to using
509 # init_mm for their active mm. mm_cpumask(mm) 509 # init_mm for their active mm. mm_cpumask(mm) is used to determine which CPUs
510 # may be using mm as a lazy tlb mm. 510 # may be using mm as a lazy tlb mm.
511 # 511 #
512 # To implement this, an arch *must*: 512 # To implement this, an arch *must*:
513 # - At the time of the final mmdrop of the mm, 513 # - At the time of the final mmdrop of the mm, ensure mm_cpumask(mm) contains
514 # at least all possible CPUs in which the mm 514 # at least all possible CPUs in which the mm is lazy.
515 # - It must meet the requirements for MMU_LAZY 515 # - It must meet the requirements for MMU_LAZY_TLB_REFCOUNT=n (see above).
516 config MMU_LAZY_TLB_SHOOTDOWN 516 config MMU_LAZY_TLB_SHOOTDOWN
517 bool 517 bool
518 518
519 config ARCH_HAVE_NMI_SAFE_CMPXCHG 519 config ARCH_HAVE_NMI_SAFE_CMPXCHG
520 bool 520 bool
521 521
522 config ARCH_HAVE_EXTRA_ELF_NOTES 522 config ARCH_HAVE_EXTRA_ELF_NOTES
523 bool 523 bool
524 help 524 help
525 An architecture should select this i 525 An architecture should select this in order to enable adding an
526 arch-specific ELF note section to co 526 arch-specific ELF note section to core files. It must provide two
527 functions: elf_coredump_extra_notes_ 527 functions: elf_coredump_extra_notes_size() and
528 elf_coredump_extra_notes_write() whi 528 elf_coredump_extra_notes_write() which are invoked by the ELF core
529 dumper. 529 dumper.
530 530
531 config ARCH_HAS_NMI_SAFE_THIS_CPU_OPS 531 config ARCH_HAS_NMI_SAFE_THIS_CPU_OPS
532 bool 532 bool
533 533
534 config HAVE_ALIGNED_STRUCT_PAGE 534 config HAVE_ALIGNED_STRUCT_PAGE
535 bool 535 bool
536 help 536 help
537 This makes sure that struct pages ar 537 This makes sure that struct pages are double word aligned and that
538 e.g. the SLUB allocator can perform 538 e.g. the SLUB allocator can perform double word atomic operations
539 on a struct page for better performa 539 on a struct page for better performance. However selecting this
540 might increase the size of a struct 540 might increase the size of a struct page by a word.
541 541
542 config HAVE_CMPXCHG_LOCAL 542 config HAVE_CMPXCHG_LOCAL
543 bool 543 bool
544 544
545 config HAVE_CMPXCHG_DOUBLE 545 config HAVE_CMPXCHG_DOUBLE
546 bool 546 bool
547 547
548 config ARCH_WEAK_RELEASE_ACQUIRE 548 config ARCH_WEAK_RELEASE_ACQUIRE
549 bool 549 bool
550 550
551 config ARCH_WANT_IPC_PARSE_VERSION 551 config ARCH_WANT_IPC_PARSE_VERSION
552 bool 552 bool
553 553
554 config ARCH_WANT_COMPAT_IPC_PARSE_VERSION 554 config ARCH_WANT_COMPAT_IPC_PARSE_VERSION
555 bool 555 bool
556 556
557 config ARCH_WANT_OLD_COMPAT_IPC 557 config ARCH_WANT_OLD_COMPAT_IPC
558 select ARCH_WANT_COMPAT_IPC_PARSE_VERS 558 select ARCH_WANT_COMPAT_IPC_PARSE_VERSION
559 bool 559 bool
560 560
561 config HAVE_ARCH_SECCOMP 561 config HAVE_ARCH_SECCOMP
562 bool 562 bool
563 help 563 help
564 An arch should select this symbol to 564 An arch should select this symbol to support seccomp mode 1 (the fixed
565 syscall policy), and must provide an 565 syscall policy), and must provide an overrides for __NR_seccomp_sigreturn,
566 and compat syscalls if the asm-gener 566 and compat syscalls if the asm-generic/seccomp.h defaults need adjustment:
567 - __NR_seccomp_read_32 567 - __NR_seccomp_read_32
568 - __NR_seccomp_write_32 568 - __NR_seccomp_write_32
569 - __NR_seccomp_exit_32 569 - __NR_seccomp_exit_32
570 - __NR_seccomp_sigreturn_32 570 - __NR_seccomp_sigreturn_32
571 571
572 config HAVE_ARCH_SECCOMP_FILTER 572 config HAVE_ARCH_SECCOMP_FILTER
573 bool 573 bool
574 select HAVE_ARCH_SECCOMP 574 select HAVE_ARCH_SECCOMP
575 help 575 help
576 An arch should select this symbol if 576 An arch should select this symbol if it provides all of these things:
577 - all the requirements for HAVE_ARCH 577 - all the requirements for HAVE_ARCH_SECCOMP
578 - syscall_get_arch() 578 - syscall_get_arch()
579 - syscall_get_arguments() 579 - syscall_get_arguments()
580 - syscall_rollback() 580 - syscall_rollback()
581 - syscall_set_return_value() 581 - syscall_set_return_value()
582 - SIGSYS siginfo_t support 582 - SIGSYS siginfo_t support
583 - secure_computing is called from a 583 - secure_computing is called from a ptrace_event()-safe context
584 - secure_computing return value is c 584 - secure_computing return value is checked and a return value of -1
585 results in the system call being s 585 results in the system call being skipped immediately.
586 - seccomp syscall wired up 586 - seccomp syscall wired up
587 - if !HAVE_SPARSE_SYSCALL_NR, have S 587 - if !HAVE_SPARSE_SYSCALL_NR, have SECCOMP_ARCH_NATIVE,
588 SECCOMP_ARCH_NATIVE_NR, SECCOMP_AR 588 SECCOMP_ARCH_NATIVE_NR, SECCOMP_ARCH_NATIVE_NAME defined. If
589 COMPAT is supported, have the SECC 589 COMPAT is supported, have the SECCOMP_ARCH_COMPAT* defines too.
590 590
591 config SECCOMP 591 config SECCOMP
592 prompt "Enable seccomp to safely execu 592 prompt "Enable seccomp to safely execute untrusted bytecode"
593 def_bool y 593 def_bool y
594 depends on HAVE_ARCH_SECCOMP 594 depends on HAVE_ARCH_SECCOMP
595 help 595 help
596 This kernel feature is useful for nu 596 This kernel feature is useful for number crunching applications
597 that may need to handle untrusted by 597 that may need to handle untrusted bytecode during their
598 execution. By using pipes or other t 598 execution. By using pipes or other transports made available
599 to the process as file descriptors s 599 to the process as file descriptors supporting the read/write
600 syscalls, it's possible to isolate t 600 syscalls, it's possible to isolate those applications in their
601 own address space using seccomp. Onc 601 own address space using seccomp. Once seccomp is enabled via
602 prctl(PR_SET_SECCOMP) or the seccomp 602 prctl(PR_SET_SECCOMP) or the seccomp() syscall, it cannot be
603 disabled and the task is only allowe 603 disabled and the task is only allowed to execute a few safe
604 syscalls defined by each seccomp mod 604 syscalls defined by each seccomp mode.
605 605
606 If unsure, say Y. 606 If unsure, say Y.
607 607
608 config SECCOMP_FILTER 608 config SECCOMP_FILTER
609 def_bool y 609 def_bool y
610 depends on HAVE_ARCH_SECCOMP_FILTER && 610 depends on HAVE_ARCH_SECCOMP_FILTER && SECCOMP && NET
611 help 611 help
612 Enable tasks to build secure computi 612 Enable tasks to build secure computing environments defined
613 in terms of Berkeley Packet Filter p 613 in terms of Berkeley Packet Filter programs which implement
614 task-defined system call filtering p 614 task-defined system call filtering polices.
615 615
616 See Documentation/userspace-api/secc 616 See Documentation/userspace-api/seccomp_filter.rst for details.
617 617
618 config SECCOMP_CACHE_DEBUG 618 config SECCOMP_CACHE_DEBUG
619 bool "Show seccomp filter cache status 619 bool "Show seccomp filter cache status in /proc/pid/seccomp_cache"
620 depends on SECCOMP_FILTER && !HAVE_SPA 620 depends on SECCOMP_FILTER && !HAVE_SPARSE_SYSCALL_NR
621 depends on PROC_FS 621 depends on PROC_FS
622 help 622 help
623 This enables the /proc/pid/seccomp_c 623 This enables the /proc/pid/seccomp_cache interface to monitor
624 seccomp cache data. The file format 624 seccomp cache data. The file format is subject to change. Reading
625 the file requires CAP_SYS_ADMIN. 625 the file requires CAP_SYS_ADMIN.
626 626
627 This option is for debugging only. E 627 This option is for debugging only. Enabling presents the risk that
628 an adversary may be able to infer th 628 an adversary may be able to infer the seccomp filter logic.
629 629
630 If unsure, say N. 630 If unsure, say N.
631 631
632 config HAVE_ARCH_STACKLEAK 632 config HAVE_ARCH_STACKLEAK
633 bool 633 bool
634 help 634 help
635 An architecture should select this i 635 An architecture should select this if it has the code which
636 fills the used part of the kernel st 636 fills the used part of the kernel stack with the STACKLEAK_POISON
637 value before returning from system c 637 value before returning from system calls.
638 638
639 config HAVE_STACKPROTECTOR 639 config HAVE_STACKPROTECTOR
640 bool 640 bool
641 help 641 help
642 An arch should select this symbol if 642 An arch should select this symbol if:
643 - it has implemented a stack canary 643 - it has implemented a stack canary (e.g. __stack_chk_guard)
644 644
645 config STACKPROTECTOR 645 config STACKPROTECTOR
646 bool "Stack Protector buffer overflow 646 bool "Stack Protector buffer overflow detection"
647 depends on HAVE_STACKPROTECTOR 647 depends on HAVE_STACKPROTECTOR
648 depends on $(cc-option,-fstack-protect 648 depends on $(cc-option,-fstack-protector)
649 default y 649 default y
650 help 650 help
651 This option turns on the "stack-prot 651 This option turns on the "stack-protector" GCC feature. This
652 feature puts, at the beginning of fu 652 feature puts, at the beginning of functions, a canary value on
653 the stack just before the return add 653 the stack just before the return address, and validates
654 the value just before actually retur 654 the value just before actually returning. Stack based buffer
655 overflows (that need to overwrite th 655 overflows (that need to overwrite this return address) now also
656 overwrite the canary, which gets det 656 overwrite the canary, which gets detected and the attack is then
657 neutralized via a kernel panic. 657 neutralized via a kernel panic.
658 658
659 Functions will have the stack-protec 659 Functions will have the stack-protector canary logic added if they
660 have an 8-byte or larger character a 660 have an 8-byte or larger character array on the stack.
661 661
662 This feature requires gcc version 4. 662 This feature requires gcc version 4.2 or above, or a distribution
663 gcc with the feature backported ("-f 663 gcc with the feature backported ("-fstack-protector").
664 664
665 On an x86 "defconfig" build, this fe 665 On an x86 "defconfig" build, this feature adds canary checks to
666 about 3% of all kernel functions, wh 666 about 3% of all kernel functions, which increases kernel code size
667 by about 0.3%. 667 by about 0.3%.
668 668
669 config STACKPROTECTOR_STRONG 669 config STACKPROTECTOR_STRONG
670 bool "Strong Stack Protector" 670 bool "Strong Stack Protector"
671 depends on STACKPROTECTOR 671 depends on STACKPROTECTOR
672 depends on $(cc-option,-fstack-protect 672 depends on $(cc-option,-fstack-protector-strong)
673 default y 673 default y
674 help 674 help
675 Functions will have the stack-protec 675 Functions will have the stack-protector canary logic added in any
676 of the following conditions: 676 of the following conditions:
677 677
678 - local variable's address used as p 678 - local variable's address used as part of the right hand side of an
679 assignment or function argument 679 assignment or function argument
680 - local variable is an array (or uni 680 - local variable is an array (or union containing an array),
681 regardless of array type or length 681 regardless of array type or length
682 - uses register local variables 682 - uses register local variables
683 683
684 This feature requires gcc version 4. 684 This feature requires gcc version 4.9 or above, or a distribution
685 gcc with the feature backported ("-f 685 gcc with the feature backported ("-fstack-protector-strong").
686 686
687 On an x86 "defconfig" build, this fe 687 On an x86 "defconfig" build, this feature adds canary checks to
688 about 20% of all kernel functions, w 688 about 20% of all kernel functions, which increases the kernel code
689 size by about 2%. 689 size by about 2%.
690 690
691 config ARCH_SUPPORTS_SHADOW_CALL_STACK 691 config ARCH_SUPPORTS_SHADOW_CALL_STACK
692 bool 692 bool
693 help 693 help
694 An architecture should select this i 694 An architecture should select this if it supports the compiler's
695 Shadow Call Stack and implements run 695 Shadow Call Stack and implements runtime support for shadow stack
696 switching. 696 switching.
697 697
698 config SHADOW_CALL_STACK 698 config SHADOW_CALL_STACK
699 bool "Shadow Call Stack" 699 bool "Shadow Call Stack"
700 depends on ARCH_SUPPORTS_SHADOW_CALL_S 700 depends on ARCH_SUPPORTS_SHADOW_CALL_STACK
701 depends on DYNAMIC_FTRACE_WITH_ARGS || 701 depends on DYNAMIC_FTRACE_WITH_ARGS || DYNAMIC_FTRACE_WITH_REGS || !FUNCTION_GRAPH_TRACER
702 depends on MMU 702 depends on MMU
703 help 703 help
704 This option enables the compiler's S 704 This option enables the compiler's Shadow Call Stack, which
705 uses a shadow stack to protect funct 705 uses a shadow stack to protect function return addresses from
706 being overwritten by an attacker. Mo 706 being overwritten by an attacker. More information can be found
707 in the compiler's documentation: 707 in the compiler's documentation:
708 708
709 - Clang: https://clang.llvm.org/docs 709 - Clang: https://clang.llvm.org/docs/ShadowCallStack.html
710 - GCC: https://gcc.gnu.org/onlinedoc 710 - GCC: https://gcc.gnu.org/onlinedocs/gcc/Instrumentation-Options.html#Instrumentation-Options
711 711
712 Note that security guarantees in the 712 Note that security guarantees in the kernel differ from the
713 ones documented for user space. The 713 ones documented for user space. The kernel must store addresses
714 of shadow stacks in memory, which me 714 of shadow stacks in memory, which means an attacker capable of
715 reading and writing arbitrary memory 715 reading and writing arbitrary memory may be able to locate them
716 and hijack control flow by modifying 716 and hijack control flow by modifying the stacks.
717 717
718 config DYNAMIC_SCS 718 config DYNAMIC_SCS
719 bool 719 bool
720 help 720 help
721 Set by the arch code if it relies on 721 Set by the arch code if it relies on code patching to insert the
722 shadow call stack push and pop instr 722 shadow call stack push and pop instructions rather than on the
723 compiler. 723 compiler.
724 724
725 config LTO 725 config LTO
726 bool 726 bool
727 help 727 help
728 Selected if the kernel will be built 728 Selected if the kernel will be built using the compiler's LTO feature.
729 729
730 config LTO_CLANG 730 config LTO_CLANG
731 bool 731 bool
732 select LTO 732 select LTO
733 help 733 help
734 Selected if the kernel will be built 734 Selected if the kernel will be built using Clang's LTO feature.
735 735
736 config ARCH_SUPPORTS_LTO_CLANG 736 config ARCH_SUPPORTS_LTO_CLANG
737 bool 737 bool
738 help 738 help
739 An architecture should select this o 739 An architecture should select this option if it supports:
740 - compiling with Clang, 740 - compiling with Clang,
741 - compiling inline assembly with Cla 741 - compiling inline assembly with Clang's integrated assembler,
742 - and linking with LLD. 742 - and linking with LLD.
743 743
744 config ARCH_SUPPORTS_LTO_CLANG_THIN 744 config ARCH_SUPPORTS_LTO_CLANG_THIN
745 bool 745 bool
746 help 746 help
747 An architecture should select this o 747 An architecture should select this option if it can support Clang's
748 ThinLTO mode. 748 ThinLTO mode.
749 749
750 config HAS_LTO_CLANG 750 config HAS_LTO_CLANG
751 def_bool y 751 def_bool y
752 depends on CC_IS_CLANG && LD_IS_LLD && 752 depends on CC_IS_CLANG && LD_IS_LLD && AS_IS_LLVM
753 depends on $(success,$(NM) --help | he 753 depends on $(success,$(NM) --help | head -n 1 | grep -qi llvm)
754 depends on $(success,$(AR) --help | he 754 depends on $(success,$(AR) --help | head -n 1 | grep -qi llvm)
755 depends on ARCH_SUPPORTS_LTO_CLANG 755 depends on ARCH_SUPPORTS_LTO_CLANG
756 depends on !FTRACE_MCOUNT_USE_RECORDMC 756 depends on !FTRACE_MCOUNT_USE_RECORDMCOUNT
757 # https://github.com/ClangBuiltLinux/l 757 # https://github.com/ClangBuiltLinux/linux/issues/1721
758 depends on (!KASAN || KASAN_HW_TAGS || 758 depends on (!KASAN || KASAN_HW_TAGS || CLANG_VERSION >= 170000) || !DEBUG_INFO
759 depends on (!KCOV || CLANG_VERSION >= 759 depends on (!KCOV || CLANG_VERSION >= 170000) || !DEBUG_INFO
760 depends on !GCOV_KERNEL 760 depends on !GCOV_KERNEL
761 help 761 help
762 The compiler and Kconfig options sup 762 The compiler and Kconfig options support building with Clang's
763 LTO. 763 LTO.
764 764
765 choice 765 choice
766 prompt "Link Time Optimization (LTO)" 766 prompt "Link Time Optimization (LTO)"
767 default LTO_NONE 767 default LTO_NONE
768 help 768 help
769 This option enables Link Time Optimi 769 This option enables Link Time Optimization (LTO), which allows the
770 compiler to optimize binaries global 770 compiler to optimize binaries globally.
771 771
772 If unsure, select LTO_NONE. Note tha 772 If unsure, select LTO_NONE. Note that LTO is very resource-intensive
773 so it's disabled by default. 773 so it's disabled by default.
774 774
775 config LTO_NONE 775 config LTO_NONE
776 bool "None" 776 bool "None"
777 help 777 help
778 Build the kernel normally, without L 778 Build the kernel normally, without Link Time Optimization (LTO).
779 779
780 config LTO_CLANG_FULL 780 config LTO_CLANG_FULL
781 bool "Clang Full LTO (EXPERIMENTAL)" 781 bool "Clang Full LTO (EXPERIMENTAL)"
782 depends on HAS_LTO_CLANG 782 depends on HAS_LTO_CLANG
783 depends on !COMPILE_TEST 783 depends on !COMPILE_TEST
784 select LTO_CLANG 784 select LTO_CLANG
785 help 785 help
786 This option enables Clang's full Lin 786 This option enables Clang's full Link Time Optimization (LTO), which
787 allows the compiler to optimize the 787 allows the compiler to optimize the kernel globally. If you enable
788 this option, the compiler generates 788 this option, the compiler generates LLVM bitcode instead of ELF
789 object files, and the actual compila 789 object files, and the actual compilation from bitcode happens at
790 the LTO link step, which may take se 790 the LTO link step, which may take several minutes depending on the
791 kernel configuration. More informati 791 kernel configuration. More information can be found from LLVM's
792 documentation: 792 documentation:
793 793
794 https://llvm.org/docs/LinkTimeOpti 794 https://llvm.org/docs/LinkTimeOptimization.html
795 795
796 During link time, this option can us 796 During link time, this option can use a large amount of RAM, and
797 may take much longer than the ThinLT 797 may take much longer than the ThinLTO option.
798 798
799 config LTO_CLANG_THIN 799 config LTO_CLANG_THIN
800 bool "Clang ThinLTO (EXPERIMENTAL)" 800 bool "Clang ThinLTO (EXPERIMENTAL)"
801 depends on HAS_LTO_CLANG && ARCH_SUPPO 801 depends on HAS_LTO_CLANG && ARCH_SUPPORTS_LTO_CLANG_THIN
802 select LTO_CLANG 802 select LTO_CLANG
803 help 803 help
804 This option enables Clang's ThinLTO, 804 This option enables Clang's ThinLTO, which allows for parallel
805 optimization and faster incremental 805 optimization and faster incremental compiles compared to the
806 CONFIG_LTO_CLANG_FULL option. More i 806 CONFIG_LTO_CLANG_FULL option. More information can be found
807 from Clang's documentation: 807 from Clang's documentation:
808 808
809 https://clang.llvm.org/docs/ThinLT 809 https://clang.llvm.org/docs/ThinLTO.html
810 810
811 If unsure, say Y. 811 If unsure, say Y.
812 endchoice 812 endchoice
813 813
814 config ARCH_SUPPORTS_CFI_CLANG 814 config ARCH_SUPPORTS_CFI_CLANG
815 bool 815 bool
816 help 816 help
817 An architecture should select this o 817 An architecture should select this option if it can support Clang's
818 Control-Flow Integrity (CFI) checkin 818 Control-Flow Integrity (CFI) checking.
819 819
820 config ARCH_USES_CFI_TRAPS 820 config ARCH_USES_CFI_TRAPS
821 bool 821 bool
822 822
823 config CFI_CLANG 823 config CFI_CLANG
824 bool "Use Clang's Control Flow Integri 824 bool "Use Clang's Control Flow Integrity (CFI)"
825 depends on ARCH_SUPPORTS_CFI_CLANG 825 depends on ARCH_SUPPORTS_CFI_CLANG
826 depends on $(cc-option,-fsanitize=kcfi 826 depends on $(cc-option,-fsanitize=kcfi)
827 help 827 help
828 This option enables Clang's forward- 828 This option enables Clang's forward-edge Control Flow Integrity
829 (CFI) checking, where the compiler i 829 (CFI) checking, where the compiler injects a runtime check to each
830 indirect function call to ensure the 830 indirect function call to ensure the target is a valid function with
831 the correct static type. This restri 831 the correct static type. This restricts possible call targets and
832 makes it more difficult for an attac 832 makes it more difficult for an attacker to exploit bugs that allow
833 the modification of stored function 833 the modification of stored function pointers. More information can be
834 found from Clang's documentation: 834 found from Clang's documentation:
835 835
836 https://clang.llvm.org/docs/Contro 836 https://clang.llvm.org/docs/ControlFlowIntegrity.html
837 837
838 config CFI_ICALL_NORMALIZE_INTEGERS 838 config CFI_ICALL_NORMALIZE_INTEGERS
839 bool "Normalize CFI tags for integers" 839 bool "Normalize CFI tags for integers"
840 depends on CFI_CLANG 840 depends on CFI_CLANG
841 depends on HAVE_CFI_ICALL_NORMALIZE_IN 841 depends on HAVE_CFI_ICALL_NORMALIZE_INTEGERS_CLANG
842 help 842 help
843 This option normalizes the CFI tags 843 This option normalizes the CFI tags for integer types so that all
844 integer types of the same size and s 844 integer types of the same size and signedness receive the same CFI
845 tag. 845 tag.
846 846
847 The option is separate from CONFIG_R 847 The option is separate from CONFIG_RUST because it affects the ABI.
848 When working with build systems that 848 When working with build systems that care about the ABI, it is
849 convenient to be able to turn on thi 849 convenient to be able to turn on this flag first, before Rust is
850 turned on. 850 turned on.
851 851
852 This option is necessary for using C 852 This option is necessary for using CFI with Rust. If unsure, say N.
853 853
854 config HAVE_CFI_ICALL_NORMALIZE_INTEGERS_CLANG 854 config HAVE_CFI_ICALL_NORMALIZE_INTEGERS_CLANG
855 def_bool y 855 def_bool y
856 depends on $(cc-option,-fsanitize=kcfi 856 depends on $(cc-option,-fsanitize=kcfi -fsanitize-cfi-icall-experimental-normalize-integers)
857 # With GCOV/KASAN we need this fix: ht 857 # With GCOV/KASAN we need this fix: https://github.com/llvm/llvm-project/pull/104826
858 depends on CLANG_VERSION >= 190103 || 858 depends on CLANG_VERSION >= 190103 || (!GCOV_KERNEL && !KASAN_GENERIC && !KASAN_SW_TAGS)
859 859
860 config HAVE_CFI_ICALL_NORMALIZE_INTEGERS_RUSTC 860 config HAVE_CFI_ICALL_NORMALIZE_INTEGERS_RUSTC
861 def_bool y 861 def_bool y
862 depends on HAVE_CFI_ICALL_NORMALIZE_IN 862 depends on HAVE_CFI_ICALL_NORMALIZE_INTEGERS_CLANG
863 depends on RUSTC_VERSION >= 107900 863 depends on RUSTC_VERSION >= 107900
864 # With GCOV/KASAN we need this fix: ht 864 # With GCOV/KASAN we need this fix: https://github.com/rust-lang/rust/pull/129373
865 depends on (RUSTC_LLVM_VERSION >= 1901 865 depends on (RUSTC_LLVM_VERSION >= 190103 && RUSTC_VERSION >= 108200) || \
866 (!GCOV_KERNEL && !KASAN_GENERI 866 (!GCOV_KERNEL && !KASAN_GENERIC && !KASAN_SW_TAGS)
867 867
868 config CFI_PERMISSIVE 868 config CFI_PERMISSIVE
869 bool "Use CFI in permissive mode" 869 bool "Use CFI in permissive mode"
870 depends on CFI_CLANG 870 depends on CFI_CLANG
871 help 871 help
872 When selected, Control Flow Integrit 872 When selected, Control Flow Integrity (CFI) violations result in a
873 warning instead of a kernel panic. T 873 warning instead of a kernel panic. This option should only be used
874 for finding indirect call type misma 874 for finding indirect call type mismatches during development.
875 875
876 If unsure, say N. 876 If unsure, say N.
877 877
878 config HAVE_ARCH_WITHIN_STACK_FRAMES 878 config HAVE_ARCH_WITHIN_STACK_FRAMES
879 bool 879 bool
880 help 880 help
881 An architecture should select this i 881 An architecture should select this if it can walk the kernel stack
882 frames to determine if an object is 882 frames to determine if an object is part of either the arguments
883 or local variables (i.e. that it exc 883 or local variables (i.e. that it excludes saved return addresses,
884 and similar) by implementing an inli 884 and similar) by implementing an inline arch_within_stack_frames(),
885 which is used by CONFIG_HARDENED_USE 885 which is used by CONFIG_HARDENED_USERCOPY.
886 886
887 config HAVE_CONTEXT_TRACKING_USER 887 config HAVE_CONTEXT_TRACKING_USER
888 bool 888 bool
889 help 889 help
890 Provide kernel/user boundaries probe 890 Provide kernel/user boundaries probes necessary for subsystems
891 that need it, such as userspace RCU 891 that need it, such as userspace RCU extended quiescent state.
892 Syscalls need to be wrapped inside u 892 Syscalls need to be wrapped inside user_exit()-user_enter(), either
893 optimized behind static key or throu 893 optimized behind static key or through the slow path using TIF_NOHZ
894 flag. Exceptions handlers must be wr 894 flag. Exceptions handlers must be wrapped as well. Irqs are already
895 protected inside ct_irq_enter/ct_irq 895 protected inside ct_irq_enter/ct_irq_exit() but preemption or signal
896 handling on irq exit still need to b 896 handling on irq exit still need to be protected.
897 897
898 config HAVE_CONTEXT_TRACKING_USER_OFFSTACK 898 config HAVE_CONTEXT_TRACKING_USER_OFFSTACK
899 bool 899 bool
900 help 900 help
901 Architecture neither relies on excep 901 Architecture neither relies on exception_enter()/exception_exit()
902 nor on schedule_user(). Also preempt 902 nor on schedule_user(). Also preempt_schedule_notrace() and
903 preempt_schedule_irq() can't be call 903 preempt_schedule_irq() can't be called in a preemptible section
904 while context tracking is CT_STATE_U 904 while context tracking is CT_STATE_USER. This feature reflects a sane
905 entry implementation where the follo 905 entry implementation where the following requirements are met on
906 critical entry code, ie: before user 906 critical entry code, ie: before user_exit() or after user_enter():
907 907
908 - Critical entry code isn't preempti 908 - Critical entry code isn't preemptible (or better yet:
909 not interruptible). 909 not interruptible).
910 - No use of RCU read side critical s 910 - No use of RCU read side critical sections, unless ct_nmi_enter()
911 got called. 911 got called.
912 - No use of instrumentation, unless 912 - No use of instrumentation, unless instrumentation_begin() got
913 called. 913 called.
914 914
915 config HAVE_TIF_NOHZ 915 config HAVE_TIF_NOHZ
916 bool 916 bool
917 help 917 help
918 Arch relies on TIF_NOHZ and syscall 918 Arch relies on TIF_NOHZ and syscall slow path to implement context
919 tracking calls to user_enter()/user_ 919 tracking calls to user_enter()/user_exit().
920 920
921 config HAVE_VIRT_CPU_ACCOUNTING 921 config HAVE_VIRT_CPU_ACCOUNTING
922 bool 922 bool
923 923
924 config HAVE_VIRT_CPU_ACCOUNTING_IDLE 924 config HAVE_VIRT_CPU_ACCOUNTING_IDLE
925 bool 925 bool
926 help 926 help
927 Architecture has its own way to acco 927 Architecture has its own way to account idle CPU time and therefore
928 doesn't implement vtime_account_idle 928 doesn't implement vtime_account_idle().
929 929
930 config ARCH_HAS_SCALED_CPUTIME 930 config ARCH_HAS_SCALED_CPUTIME
931 bool 931 bool
932 932
933 config HAVE_VIRT_CPU_ACCOUNTING_GEN 933 config HAVE_VIRT_CPU_ACCOUNTING_GEN
934 bool 934 bool
935 default y if 64BIT 935 default y if 64BIT
936 help 936 help
937 With VIRT_CPU_ACCOUNTING_GEN, cputim 937 With VIRT_CPU_ACCOUNTING_GEN, cputime_t becomes 64-bit.
938 Before enabling this option, arch co 938 Before enabling this option, arch code must be audited
939 to ensure there are no races in conc 939 to ensure there are no races in concurrent read/write of
940 cputime_t. For example, reading/writ 940 cputime_t. For example, reading/writing 64-bit cputime_t on
941 some 32-bit arches may require multi 941 some 32-bit arches may require multiple accesses, so proper
942 locking is needed to protect against 942 locking is needed to protect against concurrent accesses.
943 943
944 config HAVE_IRQ_TIME_ACCOUNTING 944 config HAVE_IRQ_TIME_ACCOUNTING
945 bool 945 bool
946 help 946 help
947 Archs need to ensure they use a high 947 Archs need to ensure they use a high enough resolution clock to
948 support irq time accounting and then 948 support irq time accounting and then call enable_sched_clock_irqtime().
949 949
950 config HAVE_MOVE_PUD 950 config HAVE_MOVE_PUD
951 bool 951 bool
952 help 952 help
953 Architectures that select this are a 953 Architectures that select this are able to move page tables at the
954 PUD level. If there are only 3 page 954 PUD level. If there are only 3 page table levels, the move effectively
955 happens at the PGD level. 955 happens at the PGD level.
956 956
957 config HAVE_MOVE_PMD 957 config HAVE_MOVE_PMD
958 bool 958 bool
959 help 959 help
960 Archs that select this are able to m 960 Archs that select this are able to move page tables at the PMD level.
961 961
962 config HAVE_ARCH_TRANSPARENT_HUGEPAGE 962 config HAVE_ARCH_TRANSPARENT_HUGEPAGE
963 bool 963 bool
964 964
965 config HAVE_ARCH_TRANSPARENT_HUGEPAGE_PUD 965 config HAVE_ARCH_TRANSPARENT_HUGEPAGE_PUD
966 bool 966 bool
967 967
968 config HAVE_ARCH_HUGE_VMAP 968 config HAVE_ARCH_HUGE_VMAP
969 bool 969 bool
970 970
971 # 971 #
972 # Archs that select this would be capable of 972 # Archs that select this would be capable of PMD-sized vmaps (i.e.,
973 # arch_vmap_pmd_supported() returns true). Th 973 # arch_vmap_pmd_supported() returns true). The VM_ALLOW_HUGE_VMAP flag
974 # must be used to enable allocations to use h 974 # must be used to enable allocations to use hugepages.
975 # 975 #
976 config HAVE_ARCH_HUGE_VMALLOC 976 config HAVE_ARCH_HUGE_VMALLOC
977 depends on HAVE_ARCH_HUGE_VMAP 977 depends on HAVE_ARCH_HUGE_VMAP
978 bool 978 bool
979 979
980 config ARCH_WANT_HUGE_PMD_SHARE 980 config ARCH_WANT_HUGE_PMD_SHARE
981 bool 981 bool
982 982
983 # Archs that want to use pmd_mkwrite on kernel 983 # Archs that want to use pmd_mkwrite on kernel memory need it defined even
984 # if there are no userspace memory management 984 # if there are no userspace memory management features that use it
985 config ARCH_WANT_KERNEL_PMD_MKWRITE 985 config ARCH_WANT_KERNEL_PMD_MKWRITE
986 bool 986 bool
987 987
988 config ARCH_WANT_PMD_MKWRITE 988 config ARCH_WANT_PMD_MKWRITE
989 def_bool TRANSPARENT_HUGEPAGE || ARCH_ 989 def_bool TRANSPARENT_HUGEPAGE || ARCH_WANT_KERNEL_PMD_MKWRITE
990 990
991 config HAVE_ARCH_SOFT_DIRTY 991 config HAVE_ARCH_SOFT_DIRTY
992 bool 992 bool
993 993
994 config HAVE_MOD_ARCH_SPECIFIC 994 config HAVE_MOD_ARCH_SPECIFIC
995 bool 995 bool
996 help 996 help
997 The arch uses struct mod_arch_specif 997 The arch uses struct mod_arch_specific to store data. Many arches
998 just need a simple module loader wit 998 just need a simple module loader without arch specific data - those
999 should not enable this. 999 should not enable this.
1000 1000
1001 config MODULES_USE_ELF_RELA 1001 config MODULES_USE_ELF_RELA
1002 bool 1002 bool
1003 help 1003 help
1004 Modules only use ELF RELA relocatio 1004 Modules only use ELF RELA relocations. Modules with ELF REL
1005 relocations will give an error. 1005 relocations will give an error.
1006 1006
1007 config MODULES_USE_ELF_REL 1007 config MODULES_USE_ELF_REL
1008 bool 1008 bool
1009 help 1009 help
1010 Modules only use ELF REL relocation 1010 Modules only use ELF REL relocations. Modules with ELF RELA
1011 relocations will give an error. 1011 relocations will give an error.
1012 1012
1013 config ARCH_WANTS_MODULES_DATA_IN_VMALLOC 1013 config ARCH_WANTS_MODULES_DATA_IN_VMALLOC
1014 bool 1014 bool
1015 help 1015 help
1016 For architectures like powerpc/32 w 1016 For architectures like powerpc/32 which have constraints on module
1017 allocation and need to allocate mod 1017 allocation and need to allocate module data outside of module area.
1018 1018
1019 config ARCH_WANTS_EXECMEM_LATE 1019 config ARCH_WANTS_EXECMEM_LATE
1020 bool 1020 bool
1021 help 1021 help
1022 For architectures that do not alloc 1022 For architectures that do not allocate executable memory early on
1023 boot, but rather require its initia 1023 boot, but rather require its initialization late when there is
1024 enough entropy for module space ran 1024 enough entropy for module space randomization, for instance
1025 arm64. 1025 arm64.
1026 1026
1027 config HAVE_IRQ_EXIT_ON_IRQ_STACK 1027 config HAVE_IRQ_EXIT_ON_IRQ_STACK
1028 bool 1028 bool
1029 help 1029 help
1030 Architecture doesn't only execute t 1030 Architecture doesn't only execute the irq handler on the irq stack
1031 but also irq_exit(). This way we ca 1031 but also irq_exit(). This way we can process softirqs on this irq
1032 stack instead of switching to a new 1032 stack instead of switching to a new one when we call __do_softirq()
1033 in the end of an hardirq. 1033 in the end of an hardirq.
1034 This spares a stack switch and impr 1034 This spares a stack switch and improves cache usage on softirq
1035 processing. 1035 processing.
1036 1036
1037 config HAVE_SOFTIRQ_ON_OWN_STACK 1037 config HAVE_SOFTIRQ_ON_OWN_STACK
1038 bool 1038 bool
1039 help 1039 help
1040 Architecture provides a function to 1040 Architecture provides a function to run __do_softirq() on a
1041 separate stack. 1041 separate stack.
1042 1042
1043 config SOFTIRQ_ON_OWN_STACK 1043 config SOFTIRQ_ON_OWN_STACK
1044 def_bool HAVE_SOFTIRQ_ON_OWN_STACK && 1044 def_bool HAVE_SOFTIRQ_ON_OWN_STACK && !PREEMPT_RT
1045 1045
1046 config ALTERNATE_USER_ADDRESS_SPACE 1046 config ALTERNATE_USER_ADDRESS_SPACE
1047 bool 1047 bool
1048 help 1048 help
1049 Architectures set this when the CPU 1049 Architectures set this when the CPU uses separate address
1050 spaces for kernel and user space po 1050 spaces for kernel and user space pointers. In this case, the
1051 access_ok() check on a __user point 1051 access_ok() check on a __user pointer is skipped.
1052 1052
1053 config PGTABLE_LEVELS 1053 config PGTABLE_LEVELS
1054 int 1054 int
1055 default 2 1055 default 2
1056 1056
1057 config ARCH_HAS_ELF_RANDOMIZE 1057 config ARCH_HAS_ELF_RANDOMIZE
1058 bool 1058 bool
1059 help 1059 help
1060 An architecture supports choosing r 1060 An architecture supports choosing randomized locations for
1061 stack, mmap, brk, and ET_DYN. Defin 1061 stack, mmap, brk, and ET_DYN. Defined functions:
1062 - arch_mmap_rnd() 1062 - arch_mmap_rnd()
1063 - arch_randomize_brk() 1063 - arch_randomize_brk()
1064 1064
1065 config HAVE_ARCH_MMAP_RND_BITS 1065 config HAVE_ARCH_MMAP_RND_BITS
1066 bool 1066 bool
1067 help 1067 help
1068 An arch should select this symbol i 1068 An arch should select this symbol if it supports setting a variable
1069 number of bits for use in establish 1069 number of bits for use in establishing the base address for mmap
1070 allocations, has MMU enabled and pr 1070 allocations, has MMU enabled and provides values for both:
1071 - ARCH_MMAP_RND_BITS_MIN 1071 - ARCH_MMAP_RND_BITS_MIN
1072 - ARCH_MMAP_RND_BITS_MAX 1072 - ARCH_MMAP_RND_BITS_MAX
1073 1073
1074 config HAVE_EXIT_THREAD 1074 config HAVE_EXIT_THREAD
1075 bool 1075 bool
1076 help 1076 help
1077 An architecture implements exit_thr 1077 An architecture implements exit_thread.
1078 1078
1079 config ARCH_MMAP_RND_BITS_MIN 1079 config ARCH_MMAP_RND_BITS_MIN
1080 int 1080 int
1081 1081
1082 config ARCH_MMAP_RND_BITS_MAX 1082 config ARCH_MMAP_RND_BITS_MAX
1083 int 1083 int
1084 1084
1085 config ARCH_MMAP_RND_BITS_DEFAULT 1085 config ARCH_MMAP_RND_BITS_DEFAULT
1086 int 1086 int
1087 1087
1088 config ARCH_MMAP_RND_BITS 1088 config ARCH_MMAP_RND_BITS
1089 int "Number of bits to use for ASLR o 1089 int "Number of bits to use for ASLR of mmap base address" if EXPERT
1090 range ARCH_MMAP_RND_BITS_MIN ARCH_MMA 1090 range ARCH_MMAP_RND_BITS_MIN ARCH_MMAP_RND_BITS_MAX
1091 default ARCH_MMAP_RND_BITS_DEFAULT if 1091 default ARCH_MMAP_RND_BITS_DEFAULT if ARCH_MMAP_RND_BITS_DEFAULT
1092 default ARCH_MMAP_RND_BITS_MIN 1092 default ARCH_MMAP_RND_BITS_MIN
1093 depends on HAVE_ARCH_MMAP_RND_BITS 1093 depends on HAVE_ARCH_MMAP_RND_BITS
1094 help 1094 help
1095 This value can be used to select th 1095 This value can be used to select the number of bits to use to
1096 determine the random offset to the 1096 determine the random offset to the base address of vma regions
1097 resulting from mmap allocations. Th 1097 resulting from mmap allocations. This value will be bounded
1098 by the architecture's minimum and m 1098 by the architecture's minimum and maximum supported values.
1099 1099
1100 This value can be changed after boo 1100 This value can be changed after boot using the
1101 /proc/sys/vm/mmap_rnd_bits tunable 1101 /proc/sys/vm/mmap_rnd_bits tunable
1102 1102
1103 config HAVE_ARCH_MMAP_RND_COMPAT_BITS 1103 config HAVE_ARCH_MMAP_RND_COMPAT_BITS
1104 bool 1104 bool
1105 help 1105 help
1106 An arch should select this symbol i 1106 An arch should select this symbol if it supports running applications
1107 in compatibility mode, supports set 1107 in compatibility mode, supports setting a variable number of bits for
1108 use in establishing the base addres 1108 use in establishing the base address for mmap allocations, has MMU
1109 enabled and provides values for bot 1109 enabled and provides values for both:
1110 - ARCH_MMAP_RND_COMPAT_BITS_MIN 1110 - ARCH_MMAP_RND_COMPAT_BITS_MIN
1111 - ARCH_MMAP_RND_COMPAT_BITS_MAX 1111 - ARCH_MMAP_RND_COMPAT_BITS_MAX
1112 1112
1113 config ARCH_MMAP_RND_COMPAT_BITS_MIN 1113 config ARCH_MMAP_RND_COMPAT_BITS_MIN
1114 int 1114 int
1115 1115
1116 config ARCH_MMAP_RND_COMPAT_BITS_MAX 1116 config ARCH_MMAP_RND_COMPAT_BITS_MAX
1117 int 1117 int
1118 1118
1119 config ARCH_MMAP_RND_COMPAT_BITS_DEFAULT 1119 config ARCH_MMAP_RND_COMPAT_BITS_DEFAULT
1120 int 1120 int
1121 1121
1122 config ARCH_MMAP_RND_COMPAT_BITS 1122 config ARCH_MMAP_RND_COMPAT_BITS
1123 int "Number of bits to use for ASLR o 1123 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 1124 range ARCH_MMAP_RND_COMPAT_BITS_MIN ARCH_MMAP_RND_COMPAT_BITS_MAX
1125 default ARCH_MMAP_RND_COMPAT_BITS_DEF 1125 default ARCH_MMAP_RND_COMPAT_BITS_DEFAULT if ARCH_MMAP_RND_COMPAT_BITS_DEFAULT
1126 default ARCH_MMAP_RND_COMPAT_BITS_MIN 1126 default ARCH_MMAP_RND_COMPAT_BITS_MIN
1127 depends on HAVE_ARCH_MMAP_RND_COMPAT_ 1127 depends on HAVE_ARCH_MMAP_RND_COMPAT_BITS
1128 help 1128 help
1129 This value can be used to select th 1129 This value can be used to select the number of bits to use to
1130 determine the random offset to the 1130 determine the random offset to the base address of vma regions
1131 resulting from mmap allocations for 1131 resulting from mmap allocations for compatible applications This
1132 value will be bounded by the archit 1132 value will be bounded by the architecture's minimum and maximum
1133 supported values. 1133 supported values.
1134 1134
1135 This value can be changed after boo 1135 This value can be changed after boot using the
1136 /proc/sys/vm/mmap_rnd_compat_bits t 1136 /proc/sys/vm/mmap_rnd_compat_bits tunable
1137 1137
1138 config HAVE_ARCH_COMPAT_MMAP_BASES 1138 config HAVE_ARCH_COMPAT_MMAP_BASES
1139 bool 1139 bool
1140 help 1140 help
1141 This allows 64bit applications to i 1141 This allows 64bit applications to invoke 32-bit mmap() syscall
1142 and vice-versa 32-bit applications 1142 and vice-versa 32-bit applications to call 64-bit mmap().
1143 Required for applications doing dif 1143 Required for applications doing different bitness syscalls.
1144 1144
1145 config HAVE_PAGE_SIZE_4KB 1145 config HAVE_PAGE_SIZE_4KB
1146 bool 1146 bool
1147 1147
1148 config HAVE_PAGE_SIZE_8KB 1148 config HAVE_PAGE_SIZE_8KB
1149 bool 1149 bool
1150 1150
1151 config HAVE_PAGE_SIZE_16KB 1151 config HAVE_PAGE_SIZE_16KB
1152 bool 1152 bool
1153 1153
1154 config HAVE_PAGE_SIZE_32KB 1154 config HAVE_PAGE_SIZE_32KB
1155 bool 1155 bool
1156 1156
1157 config HAVE_PAGE_SIZE_64KB 1157 config HAVE_PAGE_SIZE_64KB
1158 bool 1158 bool
1159 1159
1160 config HAVE_PAGE_SIZE_256KB 1160 config HAVE_PAGE_SIZE_256KB
1161 bool 1161 bool
1162 1162
1163 choice 1163 choice
1164 prompt "MMU page size" 1164 prompt "MMU page size"
1165 1165
1166 config PAGE_SIZE_4KB 1166 config PAGE_SIZE_4KB
1167 bool "4KiB pages" 1167 bool "4KiB pages"
1168 depends on HAVE_PAGE_SIZE_4KB 1168 depends on HAVE_PAGE_SIZE_4KB
1169 help 1169 help
1170 This option select the standard 4Ki 1170 This option select the standard 4KiB Linux page size and the only
1171 available option on many architectu 1171 available option on many architectures. Using 4KiB page size will
1172 minimize memory consumption and is 1172 minimize memory consumption and is therefore recommended for low
1173 memory systems. 1173 memory systems.
1174 Some software that is written for x 1174 Some software that is written for x86 systems makes incorrect
1175 assumptions about the page size and 1175 assumptions about the page size and only runs on 4KiB pages.
1176 1176
1177 config PAGE_SIZE_8KB 1177 config PAGE_SIZE_8KB
1178 bool "8KiB pages" 1178 bool "8KiB pages"
1179 depends on HAVE_PAGE_SIZE_8KB 1179 depends on HAVE_PAGE_SIZE_8KB
1180 help 1180 help
1181 This option is the only supported p 1181 This option is the only supported page size on a few older
1182 processors, and can be slightly fas 1182 processors, and can be slightly faster than 4KiB pages.
1183 1183
1184 config PAGE_SIZE_16KB 1184 config PAGE_SIZE_16KB
1185 bool "16KiB pages" 1185 bool "16KiB pages"
1186 depends on HAVE_PAGE_SIZE_16KB 1186 depends on HAVE_PAGE_SIZE_16KB
1187 help 1187 help
1188 This option is usually a good compr 1188 This option is usually a good compromise between memory
1189 consumption and performance for typ 1189 consumption and performance for typical desktop and server
1190 workloads, often saving a level of 1190 workloads, often saving a level of page table lookups compared
1191 to 4KB pages as well as reducing TL 1191 to 4KB pages as well as reducing TLB pressure and overhead of
1192 per-page operations in the kernel a 1192 per-page operations in the kernel at the expense of a larger
1193 page cache. 1193 page cache.
1194 1194
1195 config PAGE_SIZE_32KB 1195 config PAGE_SIZE_32KB
1196 bool "32KiB pages" 1196 bool "32KiB pages"
1197 depends on HAVE_PAGE_SIZE_32KB 1197 depends on HAVE_PAGE_SIZE_32KB
1198 help 1198 help
1199 Using 32KiB page size will result i 1199 Using 32KiB page size will result in slightly higher performance
1200 kernel at the price of higher memor 1200 kernel at the price of higher memory consumption compared to
1201 16KiB pages. This option is availa 1201 16KiB pages. This option is available only on cnMIPS cores.
1202 Note that you will need a suitable 1202 Note that you will need a suitable Linux distribution to
1203 support this. 1203 support this.
1204 1204
1205 config PAGE_SIZE_64KB 1205 config PAGE_SIZE_64KB
1206 bool "64KiB pages" 1206 bool "64KiB pages"
1207 depends on HAVE_PAGE_SIZE_64KB 1207 depends on HAVE_PAGE_SIZE_64KB
1208 help 1208 help
1209 Using 64KiB page size will result i 1209 Using 64KiB page size will result in slightly higher performance
1210 kernel at the price of much higher 1210 kernel at the price of much higher memory consumption compared to
1211 4KiB or 16KiB pages. 1211 4KiB or 16KiB pages.
1212 This is not suitable for general-pu 1212 This is not suitable for general-purpose workloads but the
1213 better performance may be worth the 1213 better performance may be worth the cost for certain types of
1214 supercomputing or database applicat 1214 supercomputing or database applications that work mostly with
1215 large in-memory data rather than sm 1215 large in-memory data rather than small files.
1216 1216
1217 config PAGE_SIZE_256KB 1217 config PAGE_SIZE_256KB
1218 bool "256KiB pages" 1218 bool "256KiB pages"
1219 depends on HAVE_PAGE_SIZE_256KB 1219 depends on HAVE_PAGE_SIZE_256KB
1220 help 1220 help
1221 256KiB pages have little practical 1221 256KiB pages have little practical value due to their extreme
1222 memory usage. The kernel will only 1222 memory usage. The kernel will only be able to run applications
1223 that have been compiled with '-zmax 1223 that have been compiled with '-zmax-page-size' set to 256KiB
1224 (the default is 64KiB or 4KiB on mo 1224 (the default is 64KiB or 4KiB on most architectures).
1225 1225
1226 endchoice 1226 endchoice
1227 1227
1228 config PAGE_SIZE_LESS_THAN_64KB 1228 config PAGE_SIZE_LESS_THAN_64KB
1229 def_bool y 1229 def_bool y
1230 depends on !PAGE_SIZE_64KB 1230 depends on !PAGE_SIZE_64KB
1231 depends on PAGE_SIZE_LESS_THAN_256KB 1231 depends on PAGE_SIZE_LESS_THAN_256KB
1232 1232
1233 config PAGE_SIZE_LESS_THAN_256KB 1233 config PAGE_SIZE_LESS_THAN_256KB
1234 def_bool y 1234 def_bool y
1235 depends on !PAGE_SIZE_256KB 1235 depends on !PAGE_SIZE_256KB
1236 1236
1237 config PAGE_SHIFT 1237 config PAGE_SHIFT
1238 int 1238 int
1239 default 12 if PAGE_SIZE_4KB 1239 default 12 if PAGE_SIZE_4KB
1240 default 13 if PAGE_SIZE_8KB 1240 default 13 if PAGE_SIZE_8KB
1241 default 14 if PAGE_SIZE_16KB 1241 default 14 if PAGE_SIZE_16KB
1242 default 15 if PAGE_SIZE_32KB 1242 default 15 if PAGE_SIZE_32KB
1243 default 16 if PAGE_SIZE_64KB 1243 default 16 if PAGE_SIZE_64KB
1244 default 18 if PAGE_SIZE_256KB 1244 default 18 if PAGE_SIZE_256KB
1245 1245
1246 # This allows to use a set of generic functio 1246 # This allows to use a set of generic functions to determine mmap base
1247 # address by giving priority to top-down sche 1247 # address by giving priority to top-down scheme only if the process
1248 # is not in legacy mode (compat task, unlimit 1248 # is not in legacy mode (compat task, unlimited stack size or
1249 # sysctl_legacy_va_layout). 1249 # sysctl_legacy_va_layout).
1250 # Architecture that selects this option can p 1250 # Architecture that selects this option can provide its own version of:
1251 # - STACK_RND_MASK 1251 # - STACK_RND_MASK
1252 config ARCH_WANT_DEFAULT_TOPDOWN_MMAP_LAYOUT 1252 config ARCH_WANT_DEFAULT_TOPDOWN_MMAP_LAYOUT
1253 bool 1253 bool
1254 depends on MMU 1254 depends on MMU
1255 select ARCH_HAS_ELF_RANDOMIZE 1255 select ARCH_HAS_ELF_RANDOMIZE
1256 1256
1257 config HAVE_OBJTOOL 1257 config HAVE_OBJTOOL
1258 bool 1258 bool
1259 1259
1260 config HAVE_JUMP_LABEL_HACK 1260 config HAVE_JUMP_LABEL_HACK
1261 bool 1261 bool
1262 1262
1263 config HAVE_NOINSTR_HACK 1263 config HAVE_NOINSTR_HACK
1264 bool 1264 bool
1265 1265
1266 config HAVE_NOINSTR_VALIDATION 1266 config HAVE_NOINSTR_VALIDATION
1267 bool 1267 bool
1268 1268
1269 config HAVE_UACCESS_VALIDATION 1269 config HAVE_UACCESS_VALIDATION
1270 bool 1270 bool
1271 select OBJTOOL 1271 select OBJTOOL
1272 1272
1273 config HAVE_STACK_VALIDATION 1273 config HAVE_STACK_VALIDATION
1274 bool 1274 bool
1275 help 1275 help
1276 Architecture supports objtool compi 1276 Architecture supports objtool compile-time frame pointer rule
1277 validation. 1277 validation.
1278 1278
1279 config HAVE_RELIABLE_STACKTRACE 1279 config HAVE_RELIABLE_STACKTRACE
1280 bool 1280 bool
1281 help 1281 help
1282 Architecture has either save_stack_ 1282 Architecture has either save_stack_trace_tsk_reliable() or
1283 arch_stack_walk_reliable() function 1283 arch_stack_walk_reliable() function which only returns a stack trace
1284 if it can guarantee the trace is re 1284 if it can guarantee the trace is reliable.
1285 1285
1286 config HAVE_ARCH_HASH 1286 config HAVE_ARCH_HASH
1287 bool 1287 bool
1288 default n 1288 default n
1289 help 1289 help
1290 If this is set, the architecture pr 1290 If this is set, the architecture provides an <asm/hash.h>
1291 file which provides platform-specif 1291 file which provides platform-specific implementations of some
1292 functions in <linux/hash.h> or fs/n 1292 functions in <linux/hash.h> or fs/namei.c.
1293 1293
1294 config HAVE_ARCH_NVRAM_OPS 1294 config HAVE_ARCH_NVRAM_OPS
1295 bool 1295 bool
1296 1296
1297 config ISA_BUS_API 1297 config ISA_BUS_API
1298 def_bool ISA 1298 def_bool ISA
1299 1299
1300 # 1300 #
1301 # ABI hall of shame 1301 # ABI hall of shame
1302 # 1302 #
1303 config CLONE_BACKWARDS 1303 config CLONE_BACKWARDS
1304 bool 1304 bool
1305 help 1305 help
1306 Architecture has tls passed as the 1306 Architecture has tls passed as the 4th argument of clone(2),
1307 not the 5th one. 1307 not the 5th one.
1308 1308
1309 config CLONE_BACKWARDS2 1309 config CLONE_BACKWARDS2
1310 bool 1310 bool
1311 help 1311 help
1312 Architecture has the first two argu 1312 Architecture has the first two arguments of clone(2) swapped.
1313 1313
1314 config CLONE_BACKWARDS3 1314 config CLONE_BACKWARDS3
1315 bool 1315 bool
1316 help 1316 help
1317 Architecture has tls passed as the 1317 Architecture has tls passed as the 3rd argument of clone(2),
1318 not the 5th one. 1318 not the 5th one.
1319 1319
1320 config ODD_RT_SIGACTION 1320 config ODD_RT_SIGACTION
1321 bool 1321 bool
1322 help 1322 help
1323 Architecture has unusual rt_sigacti 1323 Architecture has unusual rt_sigaction(2) arguments
1324 1324
1325 config OLD_SIGSUSPEND 1325 config OLD_SIGSUSPEND
1326 bool 1326 bool
1327 help 1327 help
1328 Architecture has old sigsuspend(2) 1328 Architecture has old sigsuspend(2) syscall, of one-argument variety
1329 1329
1330 config OLD_SIGSUSPEND3 1330 config OLD_SIGSUSPEND3
1331 bool 1331 bool
1332 help 1332 help
1333 Even weirder antique ABI - three-ar 1333 Even weirder antique ABI - three-argument sigsuspend(2)
1334 1334
1335 config OLD_SIGACTION 1335 config OLD_SIGACTION
1336 bool 1336 bool
1337 help 1337 help
1338 Architecture has old sigaction(2) s 1338 Architecture has old sigaction(2) syscall. Nope, not the same
1339 as OLD_SIGSUSPEND | OLD_SIGSUSPEND3 1339 as OLD_SIGSUSPEND | OLD_SIGSUSPEND3 - alpha has sigsuspend(2),
1340 but fairly different variant of sig 1340 but fairly different variant of sigaction(2), thanks to OSF/1
1341 compatibility... 1341 compatibility...
1342 1342
1343 config COMPAT_OLD_SIGACTION 1343 config COMPAT_OLD_SIGACTION
1344 bool 1344 bool
1345 1345
1346 config COMPAT_32BIT_TIME 1346 config COMPAT_32BIT_TIME
1347 bool "Provide system calls for 32-bit 1347 bool "Provide system calls for 32-bit time_t"
1348 default !64BIT || COMPAT 1348 default !64BIT || COMPAT
1349 help 1349 help
1350 This enables 32 bit time_t support 1350 This enables 32 bit time_t support in addition to 64 bit time_t support.
1351 This is relevant on all 32-bit arch 1351 This is relevant on all 32-bit architectures, and 64-bit architectures
1352 as part of compat syscall handling. 1352 as part of compat syscall handling.
1353 1353
1354 config ARCH_NO_PREEMPT 1354 config ARCH_NO_PREEMPT
1355 bool 1355 bool
1356 1356
1357 config ARCH_SUPPORTS_RT 1357 config ARCH_SUPPORTS_RT
1358 bool 1358 bool
1359 1359
1360 config CPU_NO_EFFICIENT_FFS 1360 config CPU_NO_EFFICIENT_FFS
1361 def_bool n 1361 def_bool n
1362 1362
1363 config HAVE_ARCH_VMAP_STACK 1363 config HAVE_ARCH_VMAP_STACK
1364 def_bool n 1364 def_bool n
1365 help 1365 help
1366 An arch should select this symbol i 1366 An arch should select this symbol if it can support kernel stacks
1367 in vmalloc space. This means: 1367 in vmalloc space. This means:
1368 1368
1369 - vmalloc space must be large enoug 1369 - vmalloc space must be large enough to hold many kernel stacks.
1370 This may rule out many 32-bit arc 1370 This may rule out many 32-bit architectures.
1371 1371
1372 - Stacks in vmalloc space need to w 1372 - Stacks in vmalloc space need to work reliably. For example, if
1373 vmap page tables are created on d 1373 vmap page tables are created on demand, either this mechanism
1374 needs to work while the stack poi 1374 needs to work while the stack points to a virtual address with
1375 unpopulated page tables or arch c 1375 unpopulated page tables or arch code (switch_to() and switch_mm(),
1376 most likely) needs to ensure that 1376 most likely) needs to ensure that the stack's page table entries
1377 are populated before running on a 1377 are populated before running on a possibly unpopulated stack.
1378 1378
1379 - If the stack overflows into a gua 1379 - If the stack overflows into a guard page, something reasonable
1380 should happen. The definition of 1380 should happen. The definition of "reasonable" is flexible, but
1381 instantly rebooting without loggi 1381 instantly rebooting without logging anything would be unfriendly.
1382 1382
1383 config VMAP_STACK 1383 config VMAP_STACK
1384 default y 1384 default y
1385 bool "Use a virtually-mapped stack" 1385 bool "Use a virtually-mapped stack"
1386 depends on HAVE_ARCH_VMAP_STACK 1386 depends on HAVE_ARCH_VMAP_STACK
1387 depends on !KASAN || KASAN_HW_TAGS || 1387 depends on !KASAN || KASAN_HW_TAGS || KASAN_VMALLOC
1388 help 1388 help
1389 Enable this if you want the use vir 1389 Enable this if you want the use virtually-mapped kernel stacks
1390 with guard pages. This causes kern 1390 with guard pages. This causes kernel stack overflows to be
1391 caught immediately rather than caus 1391 caught immediately rather than causing difficult-to-diagnose
1392 corruption. 1392 corruption.
1393 1393
1394 To use this with software KASAN mod 1394 To use this with software KASAN modes, the architecture must support
1395 backing virtual mappings with real 1395 backing virtual mappings with real shadow memory, and KASAN_VMALLOC
1396 must be enabled. 1396 must be enabled.
1397 1397
1398 config HAVE_ARCH_RANDOMIZE_KSTACK_OFFSET 1398 config HAVE_ARCH_RANDOMIZE_KSTACK_OFFSET
1399 def_bool n 1399 def_bool n
1400 help 1400 help
1401 An arch should select this symbol i 1401 An arch should select this symbol if it can support kernel stack
1402 offset randomization with calls to 1402 offset randomization with calls to add_random_kstack_offset()
1403 during syscall entry and choose_ran 1403 during syscall entry and choose_random_kstack_offset() during
1404 syscall exit. Careful removal of -f 1404 syscall exit. Careful removal of -fstack-protector-strong and
1405 -fstack-protector should also be ap 1405 -fstack-protector should also be applied to the entry code and
1406 closely examined, as the artificial 1406 closely examined, as the artificial stack bump looks like an array
1407 to the compiler, so it will attempt 1407 to the compiler, so it will attempt to add canary checks regardless
1408 of the static branch state. 1408 of the static branch state.
1409 1409
1410 config RANDOMIZE_KSTACK_OFFSET 1410 config RANDOMIZE_KSTACK_OFFSET
1411 bool "Support for randomizing kernel 1411 bool "Support for randomizing kernel stack offset on syscall entry" if EXPERT
1412 default y 1412 default y
1413 depends on HAVE_ARCH_RANDOMIZE_KSTACK 1413 depends on HAVE_ARCH_RANDOMIZE_KSTACK_OFFSET
1414 depends on INIT_STACK_NONE || !CC_IS_ 1414 depends on INIT_STACK_NONE || !CC_IS_CLANG || CLANG_VERSION >= 140000
1415 help 1415 help
1416 The kernel stack offset can be rand 1416 The kernel stack offset can be randomized (after pt_regs) by
1417 roughly 5 bits of entropy, frustrat 1417 roughly 5 bits of entropy, frustrating memory corruption
1418 attacks that depend on stack addres 1418 attacks that depend on stack address determinism or
1419 cross-syscall address exposures. 1419 cross-syscall address exposures.
1420 1420
1421 The feature is controlled via the " 1421 The feature is controlled via the "randomize_kstack_offset=on/off"
1422 kernel boot param, and if turned of 1422 kernel boot param, and if turned off has zero overhead due to its use
1423 of static branches (see JUMP_LABEL) 1423 of static branches (see JUMP_LABEL).
1424 1424
1425 If unsure, say Y. 1425 If unsure, say Y.
1426 1426
1427 config RANDOMIZE_KSTACK_OFFSET_DEFAULT 1427 config RANDOMIZE_KSTACK_OFFSET_DEFAULT
1428 bool "Default state of kernel stack o 1428 bool "Default state of kernel stack offset randomization"
1429 depends on RANDOMIZE_KSTACK_OFFSET 1429 depends on RANDOMIZE_KSTACK_OFFSET
1430 help 1430 help
1431 Kernel stack offset randomization i 1431 Kernel stack offset randomization is controlled by kernel boot param
1432 "randomize_kstack_offset=on/off", a 1432 "randomize_kstack_offset=on/off", and this config chooses the default
1433 boot state. 1433 boot state.
1434 1434
1435 config ARCH_OPTIONAL_KERNEL_RWX 1435 config ARCH_OPTIONAL_KERNEL_RWX
1436 def_bool n 1436 def_bool n
1437 1437
1438 config ARCH_OPTIONAL_KERNEL_RWX_DEFAULT 1438 config ARCH_OPTIONAL_KERNEL_RWX_DEFAULT
1439 def_bool n 1439 def_bool n
1440 1440
1441 config ARCH_HAS_STRICT_KERNEL_RWX 1441 config ARCH_HAS_STRICT_KERNEL_RWX
1442 def_bool n 1442 def_bool n
1443 1443
1444 config STRICT_KERNEL_RWX 1444 config STRICT_KERNEL_RWX
1445 bool "Make kernel text and rodata rea 1445 bool "Make kernel text and rodata read-only" if ARCH_OPTIONAL_KERNEL_RWX
1446 depends on ARCH_HAS_STRICT_KERNEL_RWX 1446 depends on ARCH_HAS_STRICT_KERNEL_RWX
1447 default !ARCH_OPTIONAL_KERNEL_RWX || 1447 default !ARCH_OPTIONAL_KERNEL_RWX || ARCH_OPTIONAL_KERNEL_RWX_DEFAULT
1448 help 1448 help
1449 If this is set, kernel text and rod 1449 If this is set, kernel text and rodata memory will be made read-only,
1450 and non-text memory will be made no 1450 and non-text memory will be made non-executable. This provides
1451 protection against certain security 1451 protection against certain security exploits (e.g. executing the heap
1452 or modifying text) 1452 or modifying text)
1453 1453
1454 These features are considered stand 1454 These features are considered standard security practice these days.
1455 You should say Y here in almost all 1455 You should say Y here in almost all cases.
1456 1456
1457 config ARCH_HAS_STRICT_MODULE_RWX 1457 config ARCH_HAS_STRICT_MODULE_RWX
1458 def_bool n 1458 def_bool n
1459 1459
1460 config STRICT_MODULE_RWX 1460 config STRICT_MODULE_RWX
1461 bool "Set loadable kernel module data 1461 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 1462 depends on ARCH_HAS_STRICT_MODULE_RWX && MODULES
1463 default !ARCH_OPTIONAL_KERNEL_RWX || 1463 default !ARCH_OPTIONAL_KERNEL_RWX || ARCH_OPTIONAL_KERNEL_RWX_DEFAULT
1464 help 1464 help
1465 If this is set, module text and rod 1465 If this is set, module text and rodata memory will be made read-only,
1466 and non-text memory will be made no 1466 and non-text memory will be made non-executable. This provides
1467 protection against certain security 1467 protection against certain security exploits (e.g. writing to text)
1468 1468
1469 # select if the architecture provides an asm/ 1469 # select if the architecture provides an asm/dma-direct.h header
1470 config ARCH_HAS_PHYS_TO_DMA 1470 config ARCH_HAS_PHYS_TO_DMA
1471 bool 1471 bool
1472 1472
1473 config HAVE_ARCH_COMPILER_H 1473 config HAVE_ARCH_COMPILER_H
1474 bool 1474 bool
1475 help 1475 help
1476 An architecture can select this if 1476 An architecture can select this if it provides an
1477 asm/compiler.h header that should b 1477 asm/compiler.h header that should be included after
1478 linux/compiler-*.h in order to over 1478 linux/compiler-*.h in order to override macro definitions that those
1479 headers generally provide. 1479 headers generally provide.
1480 1480
1481 config HAVE_ARCH_PREL32_RELOCATIONS 1481 config HAVE_ARCH_PREL32_RELOCATIONS
1482 bool 1482 bool
1483 help 1483 help
1484 May be selected by an architecture 1484 May be selected by an architecture if it supports place-relative
1485 32-bit relocations, both in the too 1485 32-bit relocations, both in the toolchain and in the module loader,
1486 in which case relative references c 1486 in which case relative references can be used in special sections
1487 for PCI fixup, initcalls etc which 1487 for PCI fixup, initcalls etc which are only half the size on 64 bit
1488 architectures, and don't require ru 1488 architectures, and don't require runtime relocation on relocatable
1489 kernels. 1489 kernels.
1490 1490
1491 config ARCH_USE_MEMREMAP_PROT 1491 config ARCH_USE_MEMREMAP_PROT
1492 bool 1492 bool
1493 1493
1494 config LOCK_EVENT_COUNTS 1494 config LOCK_EVENT_COUNTS
1495 bool "Locking event counts collection 1495 bool "Locking event counts collection"
1496 depends on DEBUG_FS 1496 depends on DEBUG_FS
1497 help 1497 help
1498 Enable light-weight counting of var 1498 Enable light-weight counting of various locking related events
1499 in the system with minimal performa 1499 in the system with minimal performance impact. This reduces
1500 the chance of application behavior 1500 the chance of application behavior change because of timing
1501 differences. The counts are reporte 1501 differences. The counts are reported via debugfs.
1502 1502
1503 # Select if the architecture has support for 1503 # Select if the architecture has support for applying RELR relocations.
1504 config ARCH_HAS_RELR 1504 config ARCH_HAS_RELR
1505 bool 1505 bool
1506 1506
1507 config RELR 1507 config RELR
1508 bool "Use RELR relocation packing" 1508 bool "Use RELR relocation packing"
1509 depends on ARCH_HAS_RELR && TOOLS_SUP 1509 depends on ARCH_HAS_RELR && TOOLS_SUPPORT_RELR
1510 default y 1510 default y
1511 help 1511 help
1512 Store the kernel's dynamic relocati 1512 Store the kernel's dynamic relocations in the RELR relocation packing
1513 format. Requires a compatible linke 1513 format. Requires a compatible linker (LLD supports this feature), as
1514 well as compatible NM and OBJCOPY u 1514 well as compatible NM and OBJCOPY utilities (llvm-nm and llvm-objcopy
1515 are compatible). 1515 are compatible).
1516 1516
1517 config ARCH_HAS_MEM_ENCRYPT 1517 config ARCH_HAS_MEM_ENCRYPT
1518 bool 1518 bool
1519 1519
1520 config ARCH_HAS_CC_PLATFORM 1520 config ARCH_HAS_CC_PLATFORM
1521 bool 1521 bool
1522 1522
1523 config HAVE_SPARSE_SYSCALL_NR 1523 config HAVE_SPARSE_SYSCALL_NR
1524 bool 1524 bool
1525 help 1525 help
1526 An architecture should select this 1526 An architecture should select this if its syscall numbering is sparse
1527 to save space. For example, MIPS ar 1527 to save space. For example, MIPS architecture has a syscall array with
1528 entries at 4000, 5000 and 6000 loca 1528 entries at 4000, 5000 and 6000 locations. This option turns on syscall
1529 related optimizations for a given a 1529 related optimizations for a given architecture.
1530 1530
1531 config ARCH_HAS_VDSO_DATA 1531 config ARCH_HAS_VDSO_DATA
1532 bool 1532 bool
1533 1533
1534 config HAVE_STATIC_CALL 1534 config HAVE_STATIC_CALL
1535 bool 1535 bool
1536 1536
1537 config HAVE_STATIC_CALL_INLINE 1537 config HAVE_STATIC_CALL_INLINE
1538 bool 1538 bool
1539 depends on HAVE_STATIC_CALL 1539 depends on HAVE_STATIC_CALL
1540 select OBJTOOL 1540 select OBJTOOL
1541 1541
1542 config HAVE_PREEMPT_DYNAMIC 1542 config HAVE_PREEMPT_DYNAMIC
1543 bool 1543 bool
1544 1544
1545 config HAVE_PREEMPT_DYNAMIC_CALL 1545 config HAVE_PREEMPT_DYNAMIC_CALL
1546 bool 1546 bool
1547 depends on HAVE_STATIC_CALL 1547 depends on HAVE_STATIC_CALL
1548 select HAVE_PREEMPT_DYNAMIC 1548 select HAVE_PREEMPT_DYNAMIC
1549 help 1549 help
1550 An architecture should select this 1550 An architecture should select this if it can handle the preemption
1551 model being selected at boot time u 1551 model being selected at boot time using static calls.
1552 1552
1553 Where an architecture selects HAVE_ 1553 Where an architecture selects HAVE_STATIC_CALL_INLINE, any call to a
1554 preemption function will be patched 1554 preemption function will be patched directly.
1555 1555
1556 Where an architecture does not sele 1556 Where an architecture does not select HAVE_STATIC_CALL_INLINE, any
1557 call to a preemption function will 1557 call to a preemption function will go through a trampoline, and the
1558 trampoline will be patched. 1558 trampoline will be patched.
1559 1559
1560 It is strongly advised to support i 1560 It is strongly advised to support inline static call to avoid any
1561 overhead. 1561 overhead.
1562 1562
1563 config HAVE_PREEMPT_DYNAMIC_KEY 1563 config HAVE_PREEMPT_DYNAMIC_KEY
1564 bool 1564 bool
1565 depends on HAVE_ARCH_JUMP_LABEL 1565 depends on HAVE_ARCH_JUMP_LABEL
1566 select HAVE_PREEMPT_DYNAMIC 1566 select HAVE_PREEMPT_DYNAMIC
1567 help 1567 help
1568 An architecture should select this 1568 An architecture should select this if it can handle the preemption
1569 model being selected at boot time u 1569 model being selected at boot time using static keys.
1570 1570
1571 Each preemption function will be gi 1571 Each preemption function will be given an early return based on a
1572 static key. This should have slight 1572 static key. This should have slightly lower overhead than non-inline
1573 static calls, as this effectively i 1573 static calls, as this effectively inlines each trampoline into the
1574 start of its callee. This may avoid 1574 start of its callee. This may avoid redundant work, and may
1575 integrate better with CFI schemes. 1575 integrate better with CFI schemes.
1576 1576
1577 This will have greater overhead tha 1577 This will have greater overhead than using inline static calls as
1578 the call to the preemption function 1578 the call to the preemption function cannot be entirely elided.
1579 1579
1580 config ARCH_WANT_LD_ORPHAN_WARN 1580 config ARCH_WANT_LD_ORPHAN_WARN
1581 bool 1581 bool
1582 help 1582 help
1583 An arch should select this symbol o 1583 An arch should select this symbol once all linker sections are explicitly
1584 included, size-asserted, or discard 1584 included, size-asserted, or discarded in the linker scripts. This is
1585 important because we never want exp 1585 important because we never want expected sections to be placed heuristically
1586 by the linker, since the locations 1586 by the linker, since the locations of such sections can change between linker
1587 versions. 1587 versions.
1588 1588
1589 config HAVE_ARCH_PFN_VALID 1589 config HAVE_ARCH_PFN_VALID
1590 bool 1590 bool
1591 1591
1592 config ARCH_SUPPORTS_DEBUG_PAGEALLOC 1592 config ARCH_SUPPORTS_DEBUG_PAGEALLOC
1593 bool 1593 bool
1594 1594
1595 config ARCH_SUPPORTS_PAGE_TABLE_CHECK 1595 config ARCH_SUPPORTS_PAGE_TABLE_CHECK
1596 bool 1596 bool
1597 1597
1598 config ARCH_SPLIT_ARG64 1598 config ARCH_SPLIT_ARG64
1599 bool 1599 bool
1600 help 1600 help
1601 If a 32-bit architecture requires 6 1601 If a 32-bit architecture requires 64-bit arguments to be split into
1602 pairs of 32-bit arguments, select t 1602 pairs of 32-bit arguments, select this option.
1603 1603
1604 config ARCH_HAS_ELFCORE_COMPAT 1604 config ARCH_HAS_ELFCORE_COMPAT
1605 bool 1605 bool
1606 1606
1607 config ARCH_HAS_PARANOID_L1D_FLUSH 1607 config ARCH_HAS_PARANOID_L1D_FLUSH
1608 bool 1608 bool
1609 1609
1610 config ARCH_HAVE_TRACE_MMIO_ACCESS 1610 config ARCH_HAVE_TRACE_MMIO_ACCESS
1611 bool 1611 bool
1612 1612
1613 config DYNAMIC_SIGFRAME 1613 config DYNAMIC_SIGFRAME
1614 bool 1614 bool
1615 1615
1616 # Select, if arch has a named attribute group 1616 # Select, if arch has a named attribute group bound to NUMA device nodes.
1617 config HAVE_ARCH_NODE_DEV_GROUP 1617 config HAVE_ARCH_NODE_DEV_GROUP
1618 bool 1618 bool
1619 1619
1620 config ARCH_HAS_HW_PTE_YOUNG 1620 config ARCH_HAS_HW_PTE_YOUNG
1621 bool 1621 bool
1622 help 1622 help
1623 Architectures that select this opti 1623 Architectures that select this option are capable of setting the
1624 accessed bit in PTE entries when us 1624 accessed bit in PTE entries when using them as part of linear address
1625 translations. Architectures that re 1625 translations. Architectures that require runtime check should select
1626 this option and override arch_has_h 1626 this option and override arch_has_hw_pte_young().
1627 1627
1628 config ARCH_HAS_NONLEAF_PMD_YOUNG 1628 config ARCH_HAS_NONLEAF_PMD_YOUNG
1629 bool 1629 bool
1630 help 1630 help
1631 Architectures that select this opti 1631 Architectures that select this option are capable of setting the
1632 accessed bit in non-leaf PMD entrie 1632 accessed bit in non-leaf PMD entries when using them as part of linear
1633 address translations. Page table wa 1633 address translations. Page table walkers that clear the accessed bit
1634 may use this capability to reduce t 1634 may use this capability to reduce their search space.
1635 1635
1636 config ARCH_HAS_KERNEL_FPU_SUPPORT 1636 config ARCH_HAS_KERNEL_FPU_SUPPORT
1637 bool 1637 bool
1638 help 1638 help
1639 Architectures that select this opti 1639 Architectures that select this option can run floating-point code in
1640 the kernel, as described in Documen 1640 the kernel, as described in Documentation/core-api/floating-point.rst.
1641 1641
1642 source "kernel/gcov/Kconfig" 1642 source "kernel/gcov/Kconfig"
1643 1643
1644 source "scripts/gcc-plugins/Kconfig" 1644 source "scripts/gcc-plugins/Kconfig"
1645 1645
1646 config FUNCTION_ALIGNMENT_4B 1646 config FUNCTION_ALIGNMENT_4B
1647 bool 1647 bool
1648 1648
1649 config FUNCTION_ALIGNMENT_8B 1649 config FUNCTION_ALIGNMENT_8B
1650 bool 1650 bool
1651 1651
1652 config FUNCTION_ALIGNMENT_16B 1652 config FUNCTION_ALIGNMENT_16B
1653 bool 1653 bool
1654 1654
1655 config FUNCTION_ALIGNMENT_32B 1655 config FUNCTION_ALIGNMENT_32B
1656 bool 1656 bool
1657 1657
1658 config FUNCTION_ALIGNMENT_64B 1658 config FUNCTION_ALIGNMENT_64B
1659 bool 1659 bool
1660 1660
1661 config FUNCTION_ALIGNMENT 1661 config FUNCTION_ALIGNMENT
1662 int 1662 int
1663 default 64 if FUNCTION_ALIGNMENT_64B 1663 default 64 if FUNCTION_ALIGNMENT_64B
1664 default 32 if FUNCTION_ALIGNMENT_32B 1664 default 32 if FUNCTION_ALIGNMENT_32B
1665 default 16 if FUNCTION_ALIGNMENT_16B 1665 default 16 if FUNCTION_ALIGNMENT_16B
1666 default 8 if FUNCTION_ALIGNMENT_8B 1666 default 8 if FUNCTION_ALIGNMENT_8B
1667 default 4 if FUNCTION_ALIGNMENT_4B 1667 default 4 if FUNCTION_ALIGNMENT_4B
1668 default 0 1668 default 0
1669 1669
1670 config CC_HAS_MIN_FUNCTION_ALIGNMENT 1670 config CC_HAS_MIN_FUNCTION_ALIGNMENT
1671 # Detect availability of the GCC opti 1671 # Detect availability of the GCC option -fmin-function-alignment which
1672 # guarantees minimal alignment for al 1672 # guarantees minimal alignment for all functions, unlike
1673 # -falign-functions which the compile 1673 # -falign-functions which the compiler ignores for cold functions.
1674 def_bool $(cc-option, -fmin-function- 1674 def_bool $(cc-option, -fmin-function-alignment=8)
1675 1675
1676 config CC_HAS_SANE_FUNCTION_ALIGNMENT 1676 config CC_HAS_SANE_FUNCTION_ALIGNMENT
1677 # Set if the guaranteed alignment wit 1677 # Set if the guaranteed alignment with -fmin-function-alignment is
1678 # available or extra care is required 1678 # available or extra care is required in the kernel. Clang provides
1679 # strict alignment always, even with 1679 # strict alignment always, even with -falign-functions.
1680 def_bool CC_HAS_MIN_FUNCTION_ALIGNMEN 1680 def_bool CC_HAS_MIN_FUNCTION_ALIGNMENT || CC_IS_CLANG
1681 1681
1682 config ARCH_NEED_CMPXCHG_1_EMU 1682 config ARCH_NEED_CMPXCHG_1_EMU
1683 bool 1683 bool
1684 1684
1685 endmenu 1685 endmenu
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