1 # SPDX-License-Identifier: GPL-2.0 1 # SPDX-License-Identifier: GPL-2.0
2 # 2 #
3 # General architecture dependent options 3 # General architecture dependent options
4 # 4 #
5 5
6 # 6 #
7 # Note: arch/$(SRCARCH)/Kconfig needs to be in 7 # Note: arch/$(SRCARCH)/Kconfig needs to be included first so that it can
8 # override the default values in this file. 8 # override the default values in this file.
9 # 9 #
10 source "arch/$(SRCARCH)/Kconfig" 10 source "arch/$(SRCARCH)/Kconfig"
11 11
12 config ARCH_CONFIGURES_CPU_MITIGATIONS <<
13 bool <<
14 <<
15 if !ARCH_CONFIGURES_CPU_MITIGATIONS <<
16 config CPU_MITIGATIONS <<
17 def_bool y <<
18 endif <<
19 <<
20 # <<
21 # Selected by architectures that need custom D <<
22 # IOMMUs not handled by dma-iommu. Drivers mu <<
23 # <<
24 config ARCH_HAS_DMA_OPS <<
25 depends on HAS_DMA <<
26 select DMA_OPS_HELPERS <<
27 bool <<
28 <<
29 menu "General architecture-dependent options" 12 menu "General architecture-dependent options"
30 13
31 config ARCH_HAS_SUBPAGE_FAULTS !! 14 config CRASH_CORE
32 bool <<
33 help <<
34 Select if the architecture can check <<
35 granularity (e.g. arm64 MTE). The pr <<
36 must be implemented. <<
37 <<
38 config HOTPLUG_SMT <<
39 bool <<
40 <<
41 config SMT_NUM_THREADS_DYNAMIC <<
42 bool 15 bool
43 16
44 # Selected by HOTPLUG_CORE_SYNC_DEAD or HOTPLU !! 17 config KEXEC_CORE
45 config HOTPLUG_CORE_SYNC !! 18 select CRASH_CORE
46 bool 19 bool
47 20
48 # Basic CPU dead synchronization selected by a !! 21 config KEXEC_ELF
49 config HOTPLUG_CORE_SYNC_DEAD <<
50 bool 22 bool
51 select HOTPLUG_CORE_SYNC <<
52 23
53 # Full CPU synchronization with alive state se !! 24 config HAVE_IMA_KEXEC
54 config HOTPLUG_CORE_SYNC_FULL <<
55 bool 25 bool
56 select HOTPLUG_CORE_SYNC_DEAD if HOTPL <<
57 select HOTPLUG_CORE_SYNC <<
58 26
59 config HOTPLUG_SPLIT_STARTUP !! 27 config SET_FS
60 bool 28 bool
61 select HOTPLUG_CORE_SYNC_FULL <<
62 29
63 config HOTPLUG_PARALLEL !! 30 config HOTPLUG_SMT
64 bool 31 bool
65 select HOTPLUG_SPLIT_STARTUP <<
66 32
67 config GENERIC_ENTRY 33 config GENERIC_ENTRY
68 bool !! 34 bool
69 35
70 config KPROBES 36 config KPROBES
71 bool "Kprobes" 37 bool "Kprobes"
>> 38 depends on MODULES
72 depends on HAVE_KPROBES 39 depends on HAVE_KPROBES
73 select KALLSYMS 40 select KALLSYMS
74 select EXECMEM <<
75 select NEED_TASKS_RCU <<
76 help 41 help
77 Kprobes allows you to trap at almost 42 Kprobes allows you to trap at almost any kernel address and
78 execute a callback function. regist 43 execute a callback function. register_kprobe() establishes
79 a probepoint and specifies the callb 44 a probepoint and specifies the callback. Kprobes is useful
80 for kernel debugging, non-intrusive 45 for kernel debugging, non-intrusive instrumentation and testing.
81 If in doubt, say "N". 46 If in doubt, say "N".
82 47
83 config JUMP_LABEL 48 config JUMP_LABEL
84 bool "Optimize very unlikely/likely br 49 bool "Optimize very unlikely/likely branches"
85 depends on HAVE_ARCH_JUMP_LABEL 50 depends on HAVE_ARCH_JUMP_LABEL
86 select OBJTOOL if HAVE_JUMP_LABEL_HACK !! 51 depends on CC_HAS_ASM_GOTO
87 help 52 help
88 This option enables a transparent br !! 53 This option enables a transparent branch optimization that
89 makes certain almost-always-true or !! 54 makes certain almost-always-true or almost-always-false branch
90 conditions even cheaper to execute w !! 55 conditions even cheaper to execute within the kernel.
91 !! 56
92 Certain performance-sensitive kernel !! 57 Certain performance-sensitive kernel code, such as trace points,
93 scheduler functionality, networking !! 58 scheduler functionality, networking code and KVM have such
94 branches and include support for thi !! 59 branches and include support for this optimization technique.
95 !! 60
96 If it is detected that the compiler !! 61 If it is detected that the compiler has support for "asm goto",
97 the kernel will compile such branche !! 62 the kernel will compile such branches with just a nop
98 instruction. When the condition flag !! 63 instruction. When the condition flag is toggled to true, the
99 nop will be converted to a jump inst !! 64 nop will be converted to a jump instruction to execute the
100 conditional block of instructions. !! 65 conditional block of instructions.
101 !! 66
102 This technique lowers overhead and s !! 67 This technique lowers overhead and stress on the branch prediction
103 of the processor and generally makes !! 68 of the processor and generally makes the kernel faster. The update
104 of the condition is slower, but thos !! 69 of the condition is slower, but those are always very rare.
105 70
106 ( On 32-bit x86, the necessary optio !! 71 ( On 32-bit x86, the necessary options added to the compiler
107 flags may increase the size of the !! 72 flags may increase the size of the kernel slightly. )
108 73
109 config STATIC_KEYS_SELFTEST 74 config STATIC_KEYS_SELFTEST
110 bool "Static key selftest" 75 bool "Static key selftest"
111 depends on JUMP_LABEL 76 depends on JUMP_LABEL
112 help 77 help
113 Boot time self-test of the branch pa 78 Boot time self-test of the branch patching code.
114 79
115 config STATIC_CALL_SELFTEST 80 config STATIC_CALL_SELFTEST
116 bool "Static call selftest" 81 bool "Static call selftest"
117 depends on HAVE_STATIC_CALL 82 depends on HAVE_STATIC_CALL
118 help 83 help
119 Boot time self-test of the call patc 84 Boot time self-test of the call patching code.
120 85
121 config OPTPROBES 86 config OPTPROBES
122 def_bool y 87 def_bool y
123 depends on KPROBES && HAVE_OPTPROBES 88 depends on KPROBES && HAVE_OPTPROBES
124 select NEED_TASKS_RCU !! 89 select TASKS_RCU if PREEMPTION
125 90
126 config KPROBES_ON_FTRACE 91 config KPROBES_ON_FTRACE
127 def_bool y 92 def_bool y
128 depends on KPROBES && HAVE_KPROBES_ON_ 93 depends on KPROBES && HAVE_KPROBES_ON_FTRACE
129 depends on DYNAMIC_FTRACE_WITH_REGS 94 depends on DYNAMIC_FTRACE_WITH_REGS
130 help 95 help
131 If function tracer is enabled and th !! 96 If function tracer is enabled and the arch supports full
132 passing of pt_regs to function traci !! 97 passing of pt_regs to function tracing, then kprobes can
133 optimize on top of function tracing. !! 98 optimize on top of function tracing.
134 99
135 config UPROBES 100 config UPROBES
136 def_bool n 101 def_bool n
137 depends on ARCH_SUPPORTS_UPROBES 102 depends on ARCH_SUPPORTS_UPROBES
138 help 103 help
139 Uprobes is the user-space counterpar 104 Uprobes is the user-space counterpart to kprobes: they
140 enable instrumentation applications 105 enable instrumentation applications (such as 'perf probe')
141 to establish unintrusive probes in u 106 to establish unintrusive probes in user-space binaries and
142 libraries, by executing handler func 107 libraries, by executing handler functions when the probes
143 are hit by user-space applications. 108 are hit by user-space applications.
144 109
145 ( These probes come in the form of s 110 ( These probes come in the form of single-byte breakpoints,
146 managed by the kernel and kept tra 111 managed by the kernel and kept transparent to the probed
147 application. ) 112 application. )
148 113
149 config HAVE_64BIT_ALIGNED_ACCESS 114 config HAVE_64BIT_ALIGNED_ACCESS
150 def_bool 64BIT && !HAVE_EFFICIENT_UNAL 115 def_bool 64BIT && !HAVE_EFFICIENT_UNALIGNED_ACCESS
151 help 116 help
152 Some architectures require 64 bit ac 117 Some architectures require 64 bit accesses to be 64 bit
153 aligned, which also requires structs 118 aligned, which also requires structs containing 64 bit values
154 to be 64 bit aligned too. This inclu 119 to be 64 bit aligned too. This includes some 32 bit
155 architectures which can do 64 bit ac 120 architectures which can do 64 bit accesses, as well as 64 bit
156 architectures without unaligned acce 121 architectures without unaligned access.
157 122
158 This symbol should be selected by an 123 This symbol should be selected by an architecture if 64 bit
159 accesses are required to be 64 bit a 124 accesses are required to be 64 bit aligned in this way even
160 though it is not a 64 bit architectu 125 though it is not a 64 bit architecture.
161 126
162 See Documentation/core-api/unaligned 127 See Documentation/core-api/unaligned-memory-access.rst for
163 more information on the topic of una 128 more information on the topic of unaligned memory accesses.
164 129
165 config HAVE_EFFICIENT_UNALIGNED_ACCESS 130 config HAVE_EFFICIENT_UNALIGNED_ACCESS
166 bool 131 bool
167 help 132 help
168 Some architectures are unable to per 133 Some architectures are unable to perform unaligned accesses
169 without the use of get_unaligned/put 134 without the use of get_unaligned/put_unaligned. Others are
170 unable to perform such accesses effi 135 unable to perform such accesses efficiently (e.g. trap on
171 unaligned access and require fixing 136 unaligned access and require fixing it up in the exception
172 handler.) 137 handler.)
173 138
174 This symbol should be selected by an 139 This symbol should be selected by an architecture if it can
175 perform unaligned accesses efficient 140 perform unaligned accesses efficiently to allow different
176 code paths to be selected for these 141 code paths to be selected for these cases. Some network
177 drivers, for example, could opt to n 142 drivers, for example, could opt to not fix up alignment
178 problems with received packets if do 143 problems with received packets if doing so would not help
179 much. 144 much.
180 145
181 See Documentation/core-api/unaligned 146 See Documentation/core-api/unaligned-memory-access.rst for more
182 information on the topic of unaligne 147 information on the topic of unaligned memory accesses.
183 148
184 config ARCH_USE_BUILTIN_BSWAP 149 config ARCH_USE_BUILTIN_BSWAP
185 bool 150 bool
186 help 151 help
187 Modern versions of GCC (since 4.4) h !! 152 Modern versions of GCC (since 4.4) have builtin functions
188 for handling byte-swapping. Using th !! 153 for handling byte-swapping. Using these, instead of the old
189 inline assembler that the architectu !! 154 inline assembler that the architecture code provides in the
190 __arch_bswapXX() macros, allows the !! 155 __arch_bswapXX() macros, allows the compiler to see what's
191 happening and offers more opportunit !! 156 happening and offers more opportunity for optimisation. In
192 particular, the compiler will be abl !! 157 particular, the compiler will be able to combine the byteswap
193 with a nearby load or store and use !! 158 with a nearby load or store and use load-and-swap or
194 store-and-swap instructions if the a !! 159 store-and-swap instructions if the architecture has them. It
195 should almost *never* result in code !! 160 should almost *never* result in code which is worse than the
196 hand-coded assembler in <asm/swab.h> !! 161 hand-coded assembler in <asm/swab.h>. But just in case it
197 does, the use of the builtins is opt !! 162 does, the use of the builtins is optional.
198 !! 163
199 Any architecture with load-and-swap !! 164 Any architecture with load-and-swap or store-and-swap
200 instructions should set this. And it !! 165 instructions should set this. And it shouldn't hurt to set it
201 on architectures that don't have suc !! 166 on architectures that don't have such instructions.
202 167
203 config KRETPROBES 168 config KRETPROBES
204 def_bool y 169 def_bool y
205 depends on KPROBES && (HAVE_KRETPROBES !! 170 depends on KPROBES && HAVE_KRETPROBES
206 <<
207 config KRETPROBE_ON_RETHOOK <<
208 def_bool y <<
209 depends on HAVE_RETHOOK <<
210 depends on KRETPROBES <<
211 select RETHOOK <<
212 171
213 config USER_RETURN_NOTIFIER 172 config USER_RETURN_NOTIFIER
214 bool 173 bool
215 depends on HAVE_USER_RETURN_NOTIFIER 174 depends on HAVE_USER_RETURN_NOTIFIER
216 help 175 help
217 Provide a kernel-internal notificati 176 Provide a kernel-internal notification when a cpu is about to
218 switch to user mode. 177 switch to user mode.
219 178
220 config HAVE_IOREMAP_PROT 179 config HAVE_IOREMAP_PROT
221 bool 180 bool
222 181
223 config HAVE_KPROBES 182 config HAVE_KPROBES
224 bool 183 bool
225 184
226 config HAVE_KRETPROBES 185 config HAVE_KRETPROBES
227 bool 186 bool
228 187
229 config HAVE_OPTPROBES 188 config HAVE_OPTPROBES
230 bool 189 bool
231 190
232 config HAVE_KPROBES_ON_FTRACE 191 config HAVE_KPROBES_ON_FTRACE
233 bool 192 bool
234 193
235 config ARCH_CORRECT_STACKTRACE_ON_KRETPROBE <<
236 bool <<
237 help <<
238 Since kretprobes modifies return add <<
239 stacktrace may see the kretprobe tra <<
240 of correct one. If the architecture <<
241 unwinder can adjust such entries, se <<
242 <<
243 config HAVE_FUNCTION_ERROR_INJECTION 194 config HAVE_FUNCTION_ERROR_INJECTION
244 bool 195 bool
245 196
246 config HAVE_NMI 197 config HAVE_NMI
247 bool 198 bool
248 199
249 config HAVE_FUNCTION_DESCRIPTORS <<
250 bool <<
251 <<
252 config TRACE_IRQFLAGS_SUPPORT <<
253 bool <<
254 <<
255 config TRACE_IRQFLAGS_NMI_SUPPORT <<
256 bool <<
257 <<
258 # 200 #
259 # An arch should select this if it provides al 201 # An arch should select this if it provides all these things:
260 # 202 #
261 # task_pt_regs() in asm/process 203 # task_pt_regs() in asm/processor.h or asm/ptrace.h
262 # arch_has_single_step() if there is ha 204 # arch_has_single_step() if there is hardware single-step support
263 # arch_has_block_step() if there is ha 205 # arch_has_block_step() if there is hardware block-step support
264 # asm/syscall.h supplying asm- 206 # asm/syscall.h supplying asm-generic/syscall.h interface
265 # linux/regset.h user_regset in 207 # linux/regset.h user_regset interfaces
266 # CORE_DUMP_USE_REGSET #define'd in l 208 # CORE_DUMP_USE_REGSET #define'd in linux/elf.h
267 # TIF_SYSCALL_TRACE calls ptrace_r !! 209 # TIF_SYSCALL_TRACE calls tracehook_report_syscall_{entry,exit}
268 # TIF_NOTIFY_RESUME calls resume_u !! 210 # TIF_NOTIFY_RESUME calls tracehook_notify_resume()
>> 211 # signal delivery calls tracehook_signal_handler()
269 # 212 #
270 config HAVE_ARCH_TRACEHOOK 213 config HAVE_ARCH_TRACEHOOK
271 bool 214 bool
272 215
273 config HAVE_DMA_CONTIGUOUS 216 config HAVE_DMA_CONTIGUOUS
274 bool 217 bool
275 218
276 config GENERIC_SMP_IDLE_THREAD 219 config GENERIC_SMP_IDLE_THREAD
277 bool 220 bool
278 221
279 config GENERIC_IDLE_POLL_SETUP 222 config GENERIC_IDLE_POLL_SETUP
280 bool 223 bool
281 224
282 config ARCH_HAS_FORTIFY_SOURCE 225 config ARCH_HAS_FORTIFY_SOURCE
283 bool 226 bool
284 help 227 help
285 An architecture should select this w 228 An architecture should select this when it can successfully
286 build and run with CONFIG_FORTIFY_SO 229 build and run with CONFIG_FORTIFY_SOURCE.
287 230
288 # 231 #
289 # Select if the arch provides a historic keepi 232 # Select if the arch provides a historic keepinit alias for the retain_initrd
290 # command line option 233 # command line option
291 # 234 #
292 config ARCH_HAS_KEEPINITRD 235 config ARCH_HAS_KEEPINITRD
293 bool 236 bool
294 237
295 # Select if arch has all set_memory_ro/rw/x/nx 238 # Select if arch has all set_memory_ro/rw/x/nx() functions in asm/cacheflush.h
296 config ARCH_HAS_SET_MEMORY 239 config ARCH_HAS_SET_MEMORY
297 bool 240 bool
298 241
299 # Select if arch has all set_direct_map_invali 242 # Select if arch has all set_direct_map_invalid/default() functions
300 config ARCH_HAS_SET_DIRECT_MAP 243 config ARCH_HAS_SET_DIRECT_MAP
301 bool 244 bool
302 245
303 # 246 #
304 # Select if the architecture provides the arch 247 # Select if the architecture provides the arch_dma_set_uncached symbol to
305 # either provide an uncached segment alias for 248 # either provide an uncached segment alias for a DMA allocation, or
306 # to remap the page tables in place. 249 # to remap the page tables in place.
307 # 250 #
308 config ARCH_HAS_DMA_SET_UNCACHED 251 config ARCH_HAS_DMA_SET_UNCACHED
309 bool 252 bool
310 253
311 # 254 #
312 # Select if the architectures provides the arc 255 # Select if the architectures provides the arch_dma_clear_uncached symbol
313 # to undo an in-place page table remap for unc 256 # to undo an in-place page table remap for uncached access.
314 # 257 #
315 config ARCH_HAS_DMA_CLEAR_UNCACHED 258 config ARCH_HAS_DMA_CLEAR_UNCACHED
316 bool 259 bool
317 260
318 config ARCH_HAS_CPU_FINALIZE_INIT !! 261 # Select if arch init_task must go in the __init_task_data section
>> 262 config ARCH_TASK_STRUCT_ON_STACK
319 bool 263 bool
320 264
321 # The architecture has a per-task state that i !! 265 # Select if arch has its private alloc_task_struct() function
322 config ARCH_HAS_CPU_PASID !! 266 config ARCH_TASK_STRUCT_ALLOCATOR
323 bool 267 bool
324 select IOMMU_MM_DATA <<
325 268
326 config HAVE_ARCH_THREAD_STRUCT_WHITELIST 269 config HAVE_ARCH_THREAD_STRUCT_WHITELIST
327 bool 270 bool
>> 271 depends on !ARCH_TASK_STRUCT_ALLOCATOR
328 help 272 help
329 An architecture should select this t 273 An architecture should select this to provide hardened usercopy
330 knowledge about what region of the t 274 knowledge about what region of the thread_struct should be
331 whitelisted for copying to userspace 275 whitelisted for copying to userspace. Normally this is only the
332 FPU registers. Specifically, arch_th 276 FPU registers. Specifically, arch_thread_struct_whitelist()
333 should be implemented. Without this, 277 should be implemented. Without this, the entire thread_struct
334 field in task_struct will be left wh 278 field in task_struct will be left whitelisted.
335 279
336 # Select if arch wants to size task_struct dyn !! 280 # Select if arch has its private alloc_thread_stack() function
337 config ARCH_WANTS_DYNAMIC_TASK_STRUCT !! 281 config ARCH_THREAD_STACK_ALLOCATOR
338 bool 282 bool
339 283
340 config ARCH_WANTS_NO_INSTR !! 284 # Select if arch wants to size task_struct dynamically via arch_task_struct_size:
>> 285 config ARCH_WANTS_DYNAMIC_TASK_STRUCT
341 bool 286 bool
342 help <<
343 An architecture should select this i <<
344 functions to denote that the toolcha <<
345 functions and is required for correc <<
346 287
347 config ARCH_32BIT_OFF_T 288 config ARCH_32BIT_OFF_T
348 bool 289 bool
349 depends on !64BIT 290 depends on !64BIT
350 help 291 help
351 All new 32-bit architectures should 292 All new 32-bit architectures should have 64-bit off_t type on
352 userspace side which corresponds to 293 userspace side which corresponds to the loff_t kernel type. This
353 is the requirement for modern ABIs. 294 is the requirement for modern ABIs. Some existing architectures
354 still support 32-bit off_t. This opt 295 still support 32-bit off_t. This option is enabled for all such
355 architectures explicitly. 296 architectures explicitly.
356 297
357 # Selected by 64 bit architectures which have 298 # Selected by 64 bit architectures which have a 32 bit f_tinode in struct ustat
358 config ARCH_32BIT_USTAT_F_TINODE 299 config ARCH_32BIT_USTAT_F_TINODE
359 bool 300 bool
360 301
361 config HAVE_ASM_MODVERSIONS 302 config HAVE_ASM_MODVERSIONS
362 bool 303 bool
363 help 304 help
364 This symbol should be selected by an 305 This symbol should be selected by an architecture if it provides
365 <asm/asm-prototypes.h> to support th 306 <asm/asm-prototypes.h> to support the module versioning for symbols
366 exported from assembly code. 307 exported from assembly code.
367 308
368 config HAVE_REGS_AND_STACK_ACCESS_API 309 config HAVE_REGS_AND_STACK_ACCESS_API
369 bool 310 bool
370 help 311 help
371 This symbol should be selected by an 312 This symbol should be selected by an architecture if it supports
372 the API needed to access registers a 313 the API needed to access registers and stack entries from pt_regs,
373 declared in asm/ptrace.h 314 declared in asm/ptrace.h
374 For example the kprobes-based event 315 For example the kprobes-based event tracer needs this API.
375 316
376 config HAVE_RSEQ 317 config HAVE_RSEQ
377 bool 318 bool
378 depends on HAVE_REGS_AND_STACK_ACCESS_ 319 depends on HAVE_REGS_AND_STACK_ACCESS_API
379 help 320 help
380 This symbol should be selected by an 321 This symbol should be selected by an architecture if it
381 supports an implementation of restar 322 supports an implementation of restartable sequences.
382 323
383 config HAVE_RUST <<
384 bool <<
385 help <<
386 This symbol should be selected by an <<
387 supports Rust. <<
388 <<
389 config HAVE_FUNCTION_ARG_ACCESS_API 324 config HAVE_FUNCTION_ARG_ACCESS_API
390 bool 325 bool
391 help 326 help
392 This symbol should be selected by an 327 This symbol should be selected by an architecture if it supports
393 the API needed to access function ar 328 the API needed to access function arguments from pt_regs,
394 declared in asm/ptrace.h 329 declared in asm/ptrace.h
395 330
396 config HAVE_HW_BREAKPOINT 331 config HAVE_HW_BREAKPOINT
397 bool 332 bool
398 depends on PERF_EVENTS 333 depends on PERF_EVENTS
399 334
400 config HAVE_MIXED_BREAKPOINTS_REGS 335 config HAVE_MIXED_BREAKPOINTS_REGS
401 bool 336 bool
402 depends on HAVE_HW_BREAKPOINT 337 depends on HAVE_HW_BREAKPOINT
403 help 338 help
404 Depending on the arch implementation 339 Depending on the arch implementation of hardware breakpoints,
405 some of them have separate registers 340 some of them have separate registers for data and instruction
406 breakpoints addresses, others have m 341 breakpoints addresses, others have mixed registers to store
407 them but define the access type in a 342 them but define the access type in a control register.
408 Select this option if your arch impl 343 Select this option if your arch implements breakpoints under the
409 latter fashion. 344 latter fashion.
410 345
411 config HAVE_USER_RETURN_NOTIFIER 346 config HAVE_USER_RETURN_NOTIFIER
412 bool 347 bool
413 348
414 config HAVE_PERF_EVENTS_NMI 349 config HAVE_PERF_EVENTS_NMI
415 bool 350 bool
416 help 351 help
417 System hardware can generate an NMI 352 System hardware can generate an NMI using the perf event
418 subsystem. Also has support for cal 353 subsystem. Also has support for calculating CPU cycle events
419 to determine how many clock cycles i 354 to determine how many clock cycles in a given period.
420 355
421 config HAVE_HARDLOCKUP_DETECTOR_PERF 356 config HAVE_HARDLOCKUP_DETECTOR_PERF
422 bool 357 bool
423 depends on HAVE_PERF_EVENTS_NMI 358 depends on HAVE_PERF_EVENTS_NMI
424 help 359 help
425 The arch chooses to use the generic 360 The arch chooses to use the generic perf-NMI-based hardlockup
426 detector. Must define HAVE_PERF_EVEN 361 detector. Must define HAVE_PERF_EVENTS_NMI.
427 362
428 config HAVE_HARDLOCKUP_DETECTOR_ARCH !! 363 config HAVE_NMI_WATCHDOG
>> 364 depends on HAVE_NMI
429 bool 365 bool
430 help 366 help
431 The arch provides its own hardlockup !! 367 The arch provides a low level NMI watchdog. It provides
432 of the generic ones. !! 368 asm/nmi.h, and defines its own arch_touch_nmi_watchdog().
433 369
434 It uses the same command line parame !! 370 config HAVE_HARDLOCKUP_DETECTOR_ARCH
435 as the generic hardlockup detectors. !! 371 bool
>> 372 select HAVE_NMI_WATCHDOG
>> 373 help
>> 374 The arch chooses to provide its own hardlockup detector, which is
>> 375 a superset of the HAVE_NMI_WATCHDOG. It also conforms to config
>> 376 interfaces and parameters provided by hardlockup detector subsystem.
436 377
437 config HAVE_PERF_REGS 378 config HAVE_PERF_REGS
438 bool 379 bool
439 help 380 help
440 Support selective register dumps for 381 Support selective register dumps for perf events. This includes
441 bit-mapping of each registers and a 382 bit-mapping of each registers and a unique architecture id.
442 383
443 config HAVE_PERF_USER_STACK_DUMP 384 config HAVE_PERF_USER_STACK_DUMP
444 bool 385 bool
445 help 386 help
446 Support user stack dumps for perf ev 387 Support user stack dumps for perf event samples. This needs
447 access to the user stack pointer whi 388 access to the user stack pointer which is not unified across
448 architectures. 389 architectures.
449 390
450 config HAVE_ARCH_JUMP_LABEL 391 config HAVE_ARCH_JUMP_LABEL
451 bool 392 bool
452 393
453 config HAVE_ARCH_JUMP_LABEL_RELATIVE 394 config HAVE_ARCH_JUMP_LABEL_RELATIVE
454 bool 395 bool
455 396
456 config MMU_GATHER_TABLE_FREE 397 config MMU_GATHER_TABLE_FREE
457 bool 398 bool
458 399
459 config MMU_GATHER_RCU_TABLE_FREE 400 config MMU_GATHER_RCU_TABLE_FREE
460 bool 401 bool
461 select MMU_GATHER_TABLE_FREE 402 select MMU_GATHER_TABLE_FREE
462 403
463 config MMU_GATHER_PAGE_SIZE 404 config MMU_GATHER_PAGE_SIZE
464 bool 405 bool
465 406
466 config MMU_GATHER_NO_RANGE 407 config MMU_GATHER_NO_RANGE
467 bool 408 bool
468 select MMU_GATHER_MERGE_VMAS <<
469 <<
470 config MMU_GATHER_NO_FLUSH_CACHE <<
471 bool <<
472 <<
473 config MMU_GATHER_MERGE_VMAS <<
474 bool <<
475 409
476 config MMU_GATHER_NO_GATHER 410 config MMU_GATHER_NO_GATHER
477 bool 411 bool
478 depends on MMU_GATHER_TABLE_FREE 412 depends on MMU_GATHER_TABLE_FREE
479 413
480 config ARCH_WANT_IRQS_OFF_ACTIVATE_MM 414 config ARCH_WANT_IRQS_OFF_ACTIVATE_MM
481 bool 415 bool
482 help 416 help
483 Temporary select until all architect 417 Temporary select until all architectures can be converted to have
484 irqs disabled over activate_mm. Arch 418 irqs disabled over activate_mm. Architectures that do IPI based TLB
485 shootdowns should enable this. 419 shootdowns should enable this.
486 420
487 # Use normal mm refcounting for MMU_LAZY_TLB k <<
488 # MMU_LAZY_TLB_REFCOUNT=n can improve the scal <<
489 # to/from kernel threads when the same mm is r <<
490 # multi-threaded application), by reducing con <<
491 # <<
492 # This can be disabled if the architecture ens <<
493 # "lazy tlb" beyond its final refcount (i.e., <<
494 # or its kernel page tables). This could be ar <<
495 # final exit(2) TLB flush, for example. <<
496 # <<
497 # To implement this, an arch *must*: <<
498 # Ensure the _lazy_tlb variants of mmgrab/mmdr <<
499 # the lazy tlb reference of a kthread's ->acti <<
500 # converted already). <<
501 config MMU_LAZY_TLB_REFCOUNT <<
502 def_bool y <<
503 depends on !MMU_LAZY_TLB_SHOOTDOWN <<
504 <<
505 # This option allows MMU_LAZY_TLB_REFCOUNT=n. <<
506 # mm as a lazy tlb beyond its last reference c <<
507 # users before the mm is deallocated. __mmdrop <<
508 # be using the mm as a lazy tlb, so that they <<
509 # init_mm for their active mm. mm_cpumask(mm) <<
510 # may be using mm as a lazy tlb mm. <<
511 # <<
512 # To implement this, an arch *must*: <<
513 # - At the time of the final mmdrop of the mm, <<
514 # at least all possible CPUs in which the mm <<
515 # - It must meet the requirements for MMU_LAZY <<
516 config MMU_LAZY_TLB_SHOOTDOWN <<
517 bool <<
518 <<
519 config ARCH_HAVE_NMI_SAFE_CMPXCHG 421 config ARCH_HAVE_NMI_SAFE_CMPXCHG
520 bool 422 bool
521 423
522 config ARCH_HAVE_EXTRA_ELF_NOTES <<
523 bool <<
524 help <<
525 An architecture should select this i <<
526 arch-specific ELF note section to co <<
527 functions: elf_coredump_extra_notes_ <<
528 elf_coredump_extra_notes_write() whi <<
529 dumper. <<
530 <<
531 config ARCH_HAS_NMI_SAFE_THIS_CPU_OPS <<
532 bool <<
533 <<
534 config HAVE_ALIGNED_STRUCT_PAGE 424 config HAVE_ALIGNED_STRUCT_PAGE
535 bool 425 bool
536 help 426 help
537 This makes sure that struct pages ar 427 This makes sure that struct pages are double word aligned and that
538 e.g. the SLUB allocator can perform 428 e.g. the SLUB allocator can perform double word atomic operations
539 on a struct page for better performa 429 on a struct page for better performance. However selecting this
540 might increase the size of a struct 430 might increase the size of a struct page by a word.
541 431
542 config HAVE_CMPXCHG_LOCAL 432 config HAVE_CMPXCHG_LOCAL
543 bool 433 bool
544 434
545 config HAVE_CMPXCHG_DOUBLE 435 config HAVE_CMPXCHG_DOUBLE
546 bool 436 bool
547 437
548 config ARCH_WEAK_RELEASE_ACQUIRE 438 config ARCH_WEAK_RELEASE_ACQUIRE
549 bool 439 bool
550 440
551 config ARCH_WANT_IPC_PARSE_VERSION 441 config ARCH_WANT_IPC_PARSE_VERSION
552 bool 442 bool
553 443
554 config ARCH_WANT_COMPAT_IPC_PARSE_VERSION 444 config ARCH_WANT_COMPAT_IPC_PARSE_VERSION
555 bool 445 bool
556 446
557 config ARCH_WANT_OLD_COMPAT_IPC 447 config ARCH_WANT_OLD_COMPAT_IPC
558 select ARCH_WANT_COMPAT_IPC_PARSE_VERS 448 select ARCH_WANT_COMPAT_IPC_PARSE_VERSION
559 bool 449 bool
560 450
561 config HAVE_ARCH_SECCOMP 451 config HAVE_ARCH_SECCOMP
562 bool 452 bool
563 help 453 help
564 An arch should select this symbol to 454 An arch should select this symbol to support seccomp mode 1 (the fixed
565 syscall policy), and must provide an 455 syscall policy), and must provide an overrides for __NR_seccomp_sigreturn,
566 and compat syscalls if the asm-gener 456 and compat syscalls if the asm-generic/seccomp.h defaults need adjustment:
567 - __NR_seccomp_read_32 457 - __NR_seccomp_read_32
568 - __NR_seccomp_write_32 458 - __NR_seccomp_write_32
569 - __NR_seccomp_exit_32 459 - __NR_seccomp_exit_32
570 - __NR_seccomp_sigreturn_32 460 - __NR_seccomp_sigreturn_32
571 461
572 config HAVE_ARCH_SECCOMP_FILTER 462 config HAVE_ARCH_SECCOMP_FILTER
573 bool 463 bool
574 select HAVE_ARCH_SECCOMP 464 select HAVE_ARCH_SECCOMP
575 help 465 help
576 An arch should select this symbol if 466 An arch should select this symbol if it provides all of these things:
577 - all the requirements for HAVE_ARCH 467 - all the requirements for HAVE_ARCH_SECCOMP
578 - syscall_get_arch() 468 - syscall_get_arch()
579 - syscall_get_arguments() 469 - syscall_get_arguments()
580 - syscall_rollback() 470 - syscall_rollback()
581 - syscall_set_return_value() 471 - syscall_set_return_value()
582 - SIGSYS siginfo_t support 472 - SIGSYS siginfo_t support
583 - secure_computing is called from a 473 - secure_computing is called from a ptrace_event()-safe context
584 - secure_computing return value is c 474 - secure_computing return value is checked and a return value of -1
585 results in the system call being s 475 results in the system call being skipped immediately.
586 - seccomp syscall wired up 476 - seccomp syscall wired up
587 - if !HAVE_SPARSE_SYSCALL_NR, have S 477 - if !HAVE_SPARSE_SYSCALL_NR, have SECCOMP_ARCH_NATIVE,
588 SECCOMP_ARCH_NATIVE_NR, SECCOMP_AR 478 SECCOMP_ARCH_NATIVE_NR, SECCOMP_ARCH_NATIVE_NAME defined. If
589 COMPAT is supported, have the SECC 479 COMPAT is supported, have the SECCOMP_ARCH_COMPAT* defines too.
590 480
591 config SECCOMP 481 config SECCOMP
592 prompt "Enable seccomp to safely execu 482 prompt "Enable seccomp to safely execute untrusted bytecode"
593 def_bool y 483 def_bool y
594 depends on HAVE_ARCH_SECCOMP 484 depends on HAVE_ARCH_SECCOMP
595 help 485 help
596 This kernel feature is useful for nu 486 This kernel feature is useful for number crunching applications
597 that may need to handle untrusted by 487 that may need to handle untrusted bytecode during their
598 execution. By using pipes or other t 488 execution. By using pipes or other transports made available
599 to the process as file descriptors s 489 to the process as file descriptors supporting the read/write
600 syscalls, it's possible to isolate t 490 syscalls, it's possible to isolate those applications in their
601 own address space using seccomp. Onc 491 own address space using seccomp. Once seccomp is enabled via
602 prctl(PR_SET_SECCOMP) or the seccomp 492 prctl(PR_SET_SECCOMP) or the seccomp() syscall, it cannot be
603 disabled and the task is only allowe 493 disabled and the task is only allowed to execute a few safe
604 syscalls defined by each seccomp mod 494 syscalls defined by each seccomp mode.
605 495
606 If unsure, say Y. 496 If unsure, say Y.
607 497
608 config SECCOMP_FILTER 498 config SECCOMP_FILTER
609 def_bool y 499 def_bool y
610 depends on HAVE_ARCH_SECCOMP_FILTER && 500 depends on HAVE_ARCH_SECCOMP_FILTER && SECCOMP && NET
611 help 501 help
612 Enable tasks to build secure computi 502 Enable tasks to build secure computing environments defined
613 in terms of Berkeley Packet Filter p 503 in terms of Berkeley Packet Filter programs which implement
614 task-defined system call filtering p 504 task-defined system call filtering polices.
615 505
616 See Documentation/userspace-api/secc 506 See Documentation/userspace-api/seccomp_filter.rst for details.
617 507
618 config SECCOMP_CACHE_DEBUG 508 config SECCOMP_CACHE_DEBUG
619 bool "Show seccomp filter cache status 509 bool "Show seccomp filter cache status in /proc/pid/seccomp_cache"
620 depends on SECCOMP_FILTER && !HAVE_SPA 510 depends on SECCOMP_FILTER && !HAVE_SPARSE_SYSCALL_NR
621 depends on PROC_FS 511 depends on PROC_FS
622 help 512 help
623 This enables the /proc/pid/seccomp_c 513 This enables the /proc/pid/seccomp_cache interface to monitor
624 seccomp cache data. The file format 514 seccomp cache data. The file format is subject to change. Reading
625 the file requires CAP_SYS_ADMIN. 515 the file requires CAP_SYS_ADMIN.
626 516
627 This option is for debugging only. E 517 This option is for debugging only. Enabling presents the risk that
628 an adversary may be able to infer th 518 an adversary may be able to infer the seccomp filter logic.
629 519
630 If unsure, say N. 520 If unsure, say N.
631 521
632 config HAVE_ARCH_STACKLEAK 522 config HAVE_ARCH_STACKLEAK
633 bool 523 bool
634 help 524 help
635 An architecture should select this i 525 An architecture should select this if it has the code which
636 fills the used part of the kernel st 526 fills the used part of the kernel stack with the STACKLEAK_POISON
637 value before returning from system c 527 value before returning from system calls.
638 528
639 config HAVE_STACKPROTECTOR 529 config HAVE_STACKPROTECTOR
640 bool 530 bool
641 help 531 help
642 An arch should select this symbol if 532 An arch should select this symbol if:
643 - it has implemented a stack canary 533 - it has implemented a stack canary (e.g. __stack_chk_guard)
644 534
645 config STACKPROTECTOR 535 config STACKPROTECTOR
646 bool "Stack Protector buffer overflow 536 bool "Stack Protector buffer overflow detection"
647 depends on HAVE_STACKPROTECTOR 537 depends on HAVE_STACKPROTECTOR
648 depends on $(cc-option,-fstack-protect 538 depends on $(cc-option,-fstack-protector)
649 default y 539 default y
650 help 540 help
651 This option turns on the "stack-prot 541 This option turns on the "stack-protector" GCC feature. This
652 feature puts, at the beginning of fu 542 feature puts, at the beginning of functions, a canary value on
653 the stack just before the return add 543 the stack just before the return address, and validates
654 the value just before actually retur 544 the value just before actually returning. Stack based buffer
655 overflows (that need to overwrite th 545 overflows (that need to overwrite this return address) now also
656 overwrite the canary, which gets det 546 overwrite the canary, which gets detected and the attack is then
657 neutralized via a kernel panic. 547 neutralized via a kernel panic.
658 548
659 Functions will have the stack-protec 549 Functions will have the stack-protector canary logic added if they
660 have an 8-byte or larger character a 550 have an 8-byte or larger character array on the stack.
661 551
662 This feature requires gcc version 4. 552 This feature requires gcc version 4.2 or above, or a distribution
663 gcc with the feature backported ("-f 553 gcc with the feature backported ("-fstack-protector").
664 554
665 On an x86 "defconfig" build, this fe 555 On an x86 "defconfig" build, this feature adds canary checks to
666 about 3% of all kernel functions, wh 556 about 3% of all kernel functions, which increases kernel code size
667 by about 0.3%. 557 by about 0.3%.
668 558
669 config STACKPROTECTOR_STRONG 559 config STACKPROTECTOR_STRONG
670 bool "Strong Stack Protector" 560 bool "Strong Stack Protector"
671 depends on STACKPROTECTOR 561 depends on STACKPROTECTOR
672 depends on $(cc-option,-fstack-protect 562 depends on $(cc-option,-fstack-protector-strong)
673 default y 563 default y
674 help 564 help
675 Functions will have the stack-protec 565 Functions will have the stack-protector canary logic added in any
676 of the following conditions: 566 of the following conditions:
677 567
678 - local variable's address used as p 568 - local variable's address used as part of the right hand side of an
679 assignment or function argument 569 assignment or function argument
680 - local variable is an array (or uni 570 - local variable is an array (or union containing an array),
681 regardless of array type or length 571 regardless of array type or length
682 - uses register local variables 572 - uses register local variables
683 573
684 This feature requires gcc version 4. 574 This feature requires gcc version 4.9 or above, or a distribution
685 gcc with the feature backported ("-f 575 gcc with the feature backported ("-fstack-protector-strong").
686 576
687 On an x86 "defconfig" build, this fe 577 On an x86 "defconfig" build, this feature adds canary checks to
688 about 20% of all kernel functions, w 578 about 20% of all kernel functions, which increases the kernel code
689 size by about 2%. 579 size by about 2%.
690 580
691 config ARCH_SUPPORTS_SHADOW_CALL_STACK 581 config ARCH_SUPPORTS_SHADOW_CALL_STACK
692 bool 582 bool
693 help 583 help
694 An architecture should select this i !! 584 An architecture should select this if it supports Clang's Shadow
695 Shadow Call Stack and implements run !! 585 Call Stack and implements runtime support for shadow stack
696 switching. 586 switching.
697 587
698 config SHADOW_CALL_STACK 588 config SHADOW_CALL_STACK
699 bool "Shadow Call Stack" !! 589 bool "Clang Shadow Call Stack"
700 depends on ARCH_SUPPORTS_SHADOW_CALL_S !! 590 depends on CC_IS_CLANG && ARCH_SUPPORTS_SHADOW_CALL_STACK
701 depends on DYNAMIC_FTRACE_WITH_ARGS || !! 591 depends on DYNAMIC_FTRACE_WITH_REGS || !FUNCTION_GRAPH_TRACER
702 depends on MMU !! 592 help
703 help !! 593 This option enables Clang's Shadow Call Stack, which uses a
704 This option enables the compiler's S !! 594 shadow stack to protect function return addresses from being
705 uses a shadow stack to protect funct !! 595 overwritten by an attacker. More information can be found in
706 being overwritten by an attacker. Mo !! 596 Clang's documentation:
707 in the compiler's documentation: <<
708 597
709 - Clang: https://clang.llvm.org/docs !! 598 https://clang.llvm.org/docs/ShadowCallStack.html
710 - GCC: https://gcc.gnu.org/onlinedoc <<
711 599
712 Note that security guarantees in the 600 Note that security guarantees in the kernel differ from the
713 ones documented for user space. The 601 ones documented for user space. The kernel must store addresses
714 of shadow stacks in memory, which me 602 of shadow stacks in memory, which means an attacker capable of
715 reading and writing arbitrary memory 603 reading and writing arbitrary memory may be able to locate them
716 and hijack control flow by modifying 604 and hijack control flow by modifying the stacks.
717 605
718 config DYNAMIC_SCS <<
719 bool <<
720 help <<
721 Set by the arch code if it relies on <<
722 shadow call stack push and pop instr <<
723 compiler. <<
724 <<
725 config LTO 606 config LTO
726 bool 607 bool
727 help 608 help
728 Selected if the kernel will be built 609 Selected if the kernel will be built using the compiler's LTO feature.
729 610
730 config LTO_CLANG 611 config LTO_CLANG
731 bool 612 bool
732 select LTO 613 select LTO
733 help 614 help
734 Selected if the kernel will be built 615 Selected if the kernel will be built using Clang's LTO feature.
735 616
736 config ARCH_SUPPORTS_LTO_CLANG 617 config ARCH_SUPPORTS_LTO_CLANG
737 bool 618 bool
738 help 619 help
739 An architecture should select this o 620 An architecture should select this option if it supports:
740 - compiling with Clang, 621 - compiling with Clang,
741 - compiling inline assembly with Cla 622 - compiling inline assembly with Clang's integrated assembler,
742 - and linking with LLD. 623 - and linking with LLD.
743 624
744 config ARCH_SUPPORTS_LTO_CLANG_THIN 625 config ARCH_SUPPORTS_LTO_CLANG_THIN
745 bool 626 bool
746 help 627 help
747 An architecture should select this o 628 An architecture should select this option if it can support Clang's
748 ThinLTO mode. 629 ThinLTO mode.
749 630
750 config HAS_LTO_CLANG 631 config HAS_LTO_CLANG
751 def_bool y 632 def_bool y
752 depends on CC_IS_CLANG && LD_IS_LLD && !! 633 # Clang >= 11: https://github.com/ClangBuiltLinux/linux/issues/510
>> 634 depends on CC_IS_CLANG && CLANG_VERSION >= 110000 && LD_IS_LLD
>> 635 depends on $(success,test $(LLVM_IAS) -eq 1)
753 depends on $(success,$(NM) --help | he 636 depends on $(success,$(NM) --help | head -n 1 | grep -qi llvm)
754 depends on $(success,$(AR) --help | he 637 depends on $(success,$(AR) --help | head -n 1 | grep -qi llvm)
755 depends on ARCH_SUPPORTS_LTO_CLANG 638 depends on ARCH_SUPPORTS_LTO_CLANG
756 depends on !FTRACE_MCOUNT_USE_RECORDMC 639 depends on !FTRACE_MCOUNT_USE_RECORDMCOUNT
757 # https://github.com/ClangBuiltLinux/l !! 640 depends on !KASAN || KASAN_HW_TAGS
758 depends on (!KASAN || KASAN_HW_TAGS || <<
759 depends on (!KCOV || CLANG_VERSION >= <<
760 depends on !GCOV_KERNEL 641 depends on !GCOV_KERNEL
761 help 642 help
762 The compiler and Kconfig options sup 643 The compiler and Kconfig options support building with Clang's
763 LTO. 644 LTO.
764 645
765 choice 646 choice
766 prompt "Link Time Optimization (LTO)" 647 prompt "Link Time Optimization (LTO)"
767 default LTO_NONE 648 default LTO_NONE
768 help 649 help
769 This option enables Link Time Optimi 650 This option enables Link Time Optimization (LTO), which allows the
770 compiler to optimize binaries global 651 compiler to optimize binaries globally.
771 652
772 If unsure, select LTO_NONE. Note tha 653 If unsure, select LTO_NONE. Note that LTO is very resource-intensive
773 so it's disabled by default. 654 so it's disabled by default.
774 655
775 config LTO_NONE 656 config LTO_NONE
776 bool "None" 657 bool "None"
777 help 658 help
778 Build the kernel normally, without L 659 Build the kernel normally, without Link Time Optimization (LTO).
779 660
780 config LTO_CLANG_FULL 661 config LTO_CLANG_FULL
781 bool "Clang Full LTO (EXPERIMENTAL)" 662 bool "Clang Full LTO (EXPERIMENTAL)"
782 depends on HAS_LTO_CLANG 663 depends on HAS_LTO_CLANG
783 depends on !COMPILE_TEST 664 depends on !COMPILE_TEST
784 select LTO_CLANG 665 select LTO_CLANG
785 help 666 help
786 This option enables Clang's full Lin !! 667 This option enables Clang's full Link Time Optimization (LTO), which
787 allows the compiler to optimize the !! 668 allows the compiler to optimize the kernel globally. If you enable
788 this option, the compiler generates !! 669 this option, the compiler generates LLVM bitcode instead of ELF
789 object files, and the actual compila !! 670 object files, and the actual compilation from bitcode happens at
790 the LTO link step, which may take se !! 671 the LTO link step, which may take several minutes depending on the
791 kernel configuration. More informati !! 672 kernel configuration. More information can be found from LLVM's
792 documentation: !! 673 documentation:
793 674
794 https://llvm.org/docs/LinkTimeOpti 675 https://llvm.org/docs/LinkTimeOptimization.html
795 676
796 During link time, this option can us 677 During link time, this option can use a large amount of RAM, and
797 may take much longer than the ThinLT 678 may take much longer than the ThinLTO option.
798 679
799 config LTO_CLANG_THIN 680 config LTO_CLANG_THIN
800 bool "Clang ThinLTO (EXPERIMENTAL)" 681 bool "Clang ThinLTO (EXPERIMENTAL)"
801 depends on HAS_LTO_CLANG && ARCH_SUPPO 682 depends on HAS_LTO_CLANG && ARCH_SUPPORTS_LTO_CLANG_THIN
802 select LTO_CLANG 683 select LTO_CLANG
803 help 684 help
804 This option enables Clang's ThinLTO, 685 This option enables Clang's ThinLTO, which allows for parallel
805 optimization and faster incremental 686 optimization and faster incremental compiles compared to the
806 CONFIG_LTO_CLANG_FULL option. More i 687 CONFIG_LTO_CLANG_FULL option. More information can be found
807 from Clang's documentation: 688 from Clang's documentation:
808 689
809 https://clang.llvm.org/docs/ThinLT 690 https://clang.llvm.org/docs/ThinLTO.html
810 691
811 If unsure, say Y. 692 If unsure, say Y.
812 endchoice 693 endchoice
813 694
814 config ARCH_SUPPORTS_CFI_CLANG <<
815 bool <<
816 help <<
817 An architecture should select this o <<
818 Control-Flow Integrity (CFI) checkin <<
819 <<
820 config ARCH_USES_CFI_TRAPS <<
821 bool <<
822 <<
823 config CFI_CLANG <<
824 bool "Use Clang's Control Flow Integri <<
825 depends on ARCH_SUPPORTS_CFI_CLANG <<
826 depends on $(cc-option,-fsanitize=kcfi <<
827 help <<
828 This option enables Clang's forward- <<
829 (CFI) checking, where the compiler i <<
830 indirect function call to ensure the <<
831 the correct static type. This restri <<
832 makes it more difficult for an attac <<
833 the modification of stored function <<
834 found from Clang's documentation: <<
835 <<
836 https://clang.llvm.org/docs/Contro <<
837 <<
838 config CFI_ICALL_NORMALIZE_INTEGERS <<
839 bool "Normalize CFI tags for integers" <<
840 depends on CFI_CLANG <<
841 depends on HAVE_CFI_ICALL_NORMALIZE_IN <<
842 help <<
843 This option normalizes the CFI tags <<
844 integer types of the same size and s <<
845 tag. <<
846 <<
847 The option is separate from CONFIG_R <<
848 When working with build systems that <<
849 convenient to be able to turn on thi <<
850 turned on. <<
851 <<
852 This option is necessary for using C <<
853 <<
854 config HAVE_CFI_ICALL_NORMALIZE_INTEGERS_CLANG <<
855 def_bool y <<
856 depends on $(cc-option,-fsanitize=kcfi <<
857 # With GCOV/KASAN we need this fix: ht <<
858 depends on CLANG_VERSION >= 190103 || <<
859 <<
860 config HAVE_CFI_ICALL_NORMALIZE_INTEGERS_RUSTC <<
861 def_bool y <<
862 depends on HAVE_CFI_ICALL_NORMALIZE_IN <<
863 depends on RUSTC_VERSION >= 107900 <<
864 # With GCOV/KASAN we need this fix: ht <<
865 depends on (RUSTC_LLVM_VERSION >= 1901 <<
866 (!GCOV_KERNEL && !KASAN_GENERI <<
867 <<
868 config CFI_PERMISSIVE <<
869 bool "Use CFI in permissive mode" <<
870 depends on CFI_CLANG <<
871 help <<
872 When selected, Control Flow Integrit <<
873 warning instead of a kernel panic. T <<
874 for finding indirect call type misma <<
875 <<
876 If unsure, say N. <<
877 <<
878 config HAVE_ARCH_WITHIN_STACK_FRAMES 695 config HAVE_ARCH_WITHIN_STACK_FRAMES
879 bool 696 bool
880 help 697 help
881 An architecture should select this i 698 An architecture should select this if it can walk the kernel stack
882 frames to determine if an object is 699 frames to determine if an object is part of either the arguments
883 or local variables (i.e. that it exc 700 or local variables (i.e. that it excludes saved return addresses,
884 and similar) by implementing an inli 701 and similar) by implementing an inline arch_within_stack_frames(),
885 which is used by CONFIG_HARDENED_USE 702 which is used by CONFIG_HARDENED_USERCOPY.
886 703
887 config HAVE_CONTEXT_TRACKING_USER !! 704 config HAVE_CONTEXT_TRACKING
888 bool 705 bool
889 help 706 help
890 Provide kernel/user boundaries probe 707 Provide kernel/user boundaries probes necessary for subsystems
891 that need it, such as userspace RCU 708 that need it, such as userspace RCU extended quiescent state.
892 Syscalls need to be wrapped inside u 709 Syscalls need to be wrapped inside user_exit()-user_enter(), either
893 optimized behind static key or throu 710 optimized behind static key or through the slow path using TIF_NOHZ
894 flag. Exceptions handlers must be wr 711 flag. Exceptions handlers must be wrapped as well. Irqs are already
895 protected inside ct_irq_enter/ct_irq !! 712 protected inside rcu_irq_enter/rcu_irq_exit() but preemption or signal
896 handling on irq exit still need to b 713 handling on irq exit still need to be protected.
897 714
898 config HAVE_CONTEXT_TRACKING_USER_OFFSTACK !! 715 config HAVE_CONTEXT_TRACKING_OFFSTACK
899 bool 716 bool
900 help 717 help
901 Architecture neither relies on excep 718 Architecture neither relies on exception_enter()/exception_exit()
902 nor on schedule_user(). Also preempt 719 nor on schedule_user(). Also preempt_schedule_notrace() and
903 preempt_schedule_irq() can't be call 720 preempt_schedule_irq() can't be called in a preemptible section
904 while context tracking is CT_STATE_U !! 721 while context tracking is CONTEXT_USER. This feature reflects a sane
905 entry implementation where the follo 722 entry implementation where the following requirements are met on
906 critical entry code, ie: before user 723 critical entry code, ie: before user_exit() or after user_enter():
907 724
908 - Critical entry code isn't preempti 725 - Critical entry code isn't preemptible (or better yet:
909 not interruptible). 726 not interruptible).
910 - No use of RCU read side critical s !! 727 - No use of RCU read side critical sections, unless rcu_nmi_enter()
911 got called. 728 got called.
912 - No use of instrumentation, unless 729 - No use of instrumentation, unless instrumentation_begin() got
913 called. 730 called.
914 731
915 config HAVE_TIF_NOHZ 732 config HAVE_TIF_NOHZ
916 bool 733 bool
917 help 734 help
918 Arch relies on TIF_NOHZ and syscall 735 Arch relies on TIF_NOHZ and syscall slow path to implement context
919 tracking calls to user_enter()/user_ 736 tracking calls to user_enter()/user_exit().
920 737
921 config HAVE_VIRT_CPU_ACCOUNTING 738 config HAVE_VIRT_CPU_ACCOUNTING
922 bool 739 bool
923 740
924 config HAVE_VIRT_CPU_ACCOUNTING_IDLE 741 config HAVE_VIRT_CPU_ACCOUNTING_IDLE
925 bool 742 bool
926 help 743 help
927 Architecture has its own way to acco 744 Architecture has its own way to account idle CPU time and therefore
928 doesn't implement vtime_account_idle 745 doesn't implement vtime_account_idle().
929 746
930 config ARCH_HAS_SCALED_CPUTIME 747 config ARCH_HAS_SCALED_CPUTIME
931 bool 748 bool
932 749
933 config HAVE_VIRT_CPU_ACCOUNTING_GEN 750 config HAVE_VIRT_CPU_ACCOUNTING_GEN
934 bool 751 bool
935 default y if 64BIT 752 default y if 64BIT
936 help 753 help
937 With VIRT_CPU_ACCOUNTING_GEN, cputim 754 With VIRT_CPU_ACCOUNTING_GEN, cputime_t becomes 64-bit.
938 Before enabling this option, arch co 755 Before enabling this option, arch code must be audited
939 to ensure there are no races in conc 756 to ensure there are no races in concurrent read/write of
940 cputime_t. For example, reading/writ 757 cputime_t. For example, reading/writing 64-bit cputime_t on
941 some 32-bit arches may require multi 758 some 32-bit arches may require multiple accesses, so proper
942 locking is needed to protect against 759 locking is needed to protect against concurrent accesses.
943 760
944 config HAVE_IRQ_TIME_ACCOUNTING 761 config HAVE_IRQ_TIME_ACCOUNTING
945 bool 762 bool
946 help 763 help
947 Archs need to ensure they use a high 764 Archs need to ensure they use a high enough resolution clock to
948 support irq time accounting and then 765 support irq time accounting and then call enable_sched_clock_irqtime().
949 766
950 config HAVE_MOVE_PUD 767 config HAVE_MOVE_PUD
951 bool 768 bool
952 help 769 help
953 Architectures that select this are a 770 Architectures that select this are able to move page tables at the
954 PUD level. If there are only 3 page 771 PUD level. If there are only 3 page table levels, the move effectively
955 happens at the PGD level. 772 happens at the PGD level.
956 773
957 config HAVE_MOVE_PMD 774 config HAVE_MOVE_PMD
958 bool 775 bool
959 help 776 help
960 Archs that select this are able to m 777 Archs that select this are able to move page tables at the PMD level.
961 778
962 config HAVE_ARCH_TRANSPARENT_HUGEPAGE 779 config HAVE_ARCH_TRANSPARENT_HUGEPAGE
963 bool 780 bool
964 781
965 config HAVE_ARCH_TRANSPARENT_HUGEPAGE_PUD 782 config HAVE_ARCH_TRANSPARENT_HUGEPAGE_PUD
966 bool 783 bool
967 784
968 config HAVE_ARCH_HUGE_VMAP 785 config HAVE_ARCH_HUGE_VMAP
969 bool 786 bool
970 787
971 # <<
972 # Archs that select this would be capable of <<
973 # arch_vmap_pmd_supported() returns true). Th <<
974 # must be used to enable allocations to use h <<
975 # <<
976 config HAVE_ARCH_HUGE_VMALLOC <<
977 depends on HAVE_ARCH_HUGE_VMAP <<
978 bool <<
979 <<
980 config ARCH_WANT_HUGE_PMD_SHARE 788 config ARCH_WANT_HUGE_PMD_SHARE
981 bool 789 bool
982 790
983 # Archs that want to use pmd_mkwrite on kernel <<
984 # if there are no userspace memory management <<
985 config ARCH_WANT_KERNEL_PMD_MKWRITE <<
986 bool <<
987 <<
988 config ARCH_WANT_PMD_MKWRITE <<
989 def_bool TRANSPARENT_HUGEPAGE || ARCH_ <<
990 <<
991 config HAVE_ARCH_SOFT_DIRTY 791 config HAVE_ARCH_SOFT_DIRTY
992 bool 792 bool
993 793
994 config HAVE_MOD_ARCH_SPECIFIC 794 config HAVE_MOD_ARCH_SPECIFIC
995 bool 795 bool
996 help 796 help
997 The arch uses struct mod_arch_specif 797 The arch uses struct mod_arch_specific to store data. Many arches
998 just need a simple module loader wit 798 just need a simple module loader without arch specific data - those
999 should not enable this. 799 should not enable this.
1000 800
1001 config MODULES_USE_ELF_RELA 801 config MODULES_USE_ELF_RELA
1002 bool 802 bool
1003 help 803 help
1004 Modules only use ELF RELA relocatio 804 Modules only use ELF RELA relocations. Modules with ELF REL
1005 relocations will give an error. 805 relocations will give an error.
1006 806
1007 config MODULES_USE_ELF_REL 807 config MODULES_USE_ELF_REL
1008 bool 808 bool
1009 help 809 help
1010 Modules only use ELF REL relocation 810 Modules only use ELF REL relocations. Modules with ELF RELA
1011 relocations will give an error. 811 relocations will give an error.
1012 812
1013 config ARCH_WANTS_MODULES_DATA_IN_VMALLOC <<
1014 bool <<
1015 help <<
1016 For architectures like powerpc/32 w <<
1017 allocation and need to allocate mod <<
1018 <<
1019 config ARCH_WANTS_EXECMEM_LATE <<
1020 bool <<
1021 help <<
1022 For architectures that do not alloc <<
1023 boot, but rather require its initia <<
1024 enough entropy for module space ran <<
1025 arm64. <<
1026 <<
1027 config HAVE_IRQ_EXIT_ON_IRQ_STACK 813 config HAVE_IRQ_EXIT_ON_IRQ_STACK
1028 bool 814 bool
1029 help 815 help
1030 Architecture doesn't only execute t 816 Architecture doesn't only execute the irq handler on the irq stack
1031 but also irq_exit(). This way we ca 817 but also irq_exit(). This way we can process softirqs on this irq
1032 stack instead of switching to a new 818 stack instead of switching to a new one when we call __do_softirq()
1033 in the end of an hardirq. 819 in the end of an hardirq.
1034 This spares a stack switch and impr 820 This spares a stack switch and improves cache usage on softirq
1035 processing. 821 processing.
1036 822
1037 config HAVE_SOFTIRQ_ON_OWN_STACK 823 config HAVE_SOFTIRQ_ON_OWN_STACK
1038 bool 824 bool
1039 help 825 help
1040 Architecture provides a function to 826 Architecture provides a function to run __do_softirq() on a
1041 separate stack. !! 827 seperate stack.
1042 <<
1043 config SOFTIRQ_ON_OWN_STACK <<
1044 def_bool HAVE_SOFTIRQ_ON_OWN_STACK && <<
1045 <<
1046 config ALTERNATE_USER_ADDRESS_SPACE <<
1047 bool <<
1048 help <<
1049 Architectures set this when the CPU <<
1050 spaces for kernel and user space po <<
1051 access_ok() check on a __user point <<
1052 828
1053 config PGTABLE_LEVELS 829 config PGTABLE_LEVELS
1054 int 830 int
1055 default 2 831 default 2
1056 832
1057 config ARCH_HAS_ELF_RANDOMIZE 833 config ARCH_HAS_ELF_RANDOMIZE
1058 bool 834 bool
1059 help 835 help
1060 An architecture supports choosing r 836 An architecture supports choosing randomized locations for
1061 stack, mmap, brk, and ET_DYN. Defin 837 stack, mmap, brk, and ET_DYN. Defined functions:
1062 - arch_mmap_rnd() 838 - arch_mmap_rnd()
1063 - arch_randomize_brk() 839 - arch_randomize_brk()
1064 840
1065 config HAVE_ARCH_MMAP_RND_BITS 841 config HAVE_ARCH_MMAP_RND_BITS
1066 bool 842 bool
1067 help 843 help
1068 An arch should select this symbol i 844 An arch should select this symbol if it supports setting a variable
1069 number of bits for use in establish 845 number of bits for use in establishing the base address for mmap
1070 allocations, has MMU enabled and pr 846 allocations, has MMU enabled and provides values for both:
1071 - ARCH_MMAP_RND_BITS_MIN 847 - ARCH_MMAP_RND_BITS_MIN
1072 - ARCH_MMAP_RND_BITS_MAX 848 - ARCH_MMAP_RND_BITS_MAX
1073 849
1074 config HAVE_EXIT_THREAD 850 config HAVE_EXIT_THREAD
1075 bool 851 bool
1076 help 852 help
1077 An architecture implements exit_thr 853 An architecture implements exit_thread.
1078 854
1079 config ARCH_MMAP_RND_BITS_MIN 855 config ARCH_MMAP_RND_BITS_MIN
1080 int 856 int
1081 857
1082 config ARCH_MMAP_RND_BITS_MAX 858 config ARCH_MMAP_RND_BITS_MAX
1083 int 859 int
1084 860
1085 config ARCH_MMAP_RND_BITS_DEFAULT 861 config ARCH_MMAP_RND_BITS_DEFAULT
1086 int 862 int
1087 863
1088 config ARCH_MMAP_RND_BITS 864 config ARCH_MMAP_RND_BITS
1089 int "Number of bits to use for ASLR o 865 int "Number of bits to use for ASLR of mmap base address" if EXPERT
1090 range ARCH_MMAP_RND_BITS_MIN ARCH_MMA 866 range ARCH_MMAP_RND_BITS_MIN ARCH_MMAP_RND_BITS_MAX
1091 default ARCH_MMAP_RND_BITS_DEFAULT if 867 default ARCH_MMAP_RND_BITS_DEFAULT if ARCH_MMAP_RND_BITS_DEFAULT
1092 default ARCH_MMAP_RND_BITS_MIN 868 default ARCH_MMAP_RND_BITS_MIN
1093 depends on HAVE_ARCH_MMAP_RND_BITS 869 depends on HAVE_ARCH_MMAP_RND_BITS
1094 help 870 help
1095 This value can be used to select th 871 This value can be used to select the number of bits to use to
1096 determine the random offset to the 872 determine the random offset to the base address of vma regions
1097 resulting from mmap allocations. Th 873 resulting from mmap allocations. This value will be bounded
1098 by the architecture's minimum and m 874 by the architecture's minimum and maximum supported values.
1099 875
1100 This value can be changed after boo 876 This value can be changed after boot using the
1101 /proc/sys/vm/mmap_rnd_bits tunable 877 /proc/sys/vm/mmap_rnd_bits tunable
1102 878
1103 config HAVE_ARCH_MMAP_RND_COMPAT_BITS 879 config HAVE_ARCH_MMAP_RND_COMPAT_BITS
1104 bool 880 bool
1105 help 881 help
1106 An arch should select this symbol i 882 An arch should select this symbol if it supports running applications
1107 in compatibility mode, supports set 883 in compatibility mode, supports setting a variable number of bits for
1108 use in establishing the base addres 884 use in establishing the base address for mmap allocations, has MMU
1109 enabled and provides values for bot 885 enabled and provides values for both:
1110 - ARCH_MMAP_RND_COMPAT_BITS_MIN 886 - ARCH_MMAP_RND_COMPAT_BITS_MIN
1111 - ARCH_MMAP_RND_COMPAT_BITS_MAX 887 - ARCH_MMAP_RND_COMPAT_BITS_MAX
1112 888
1113 config ARCH_MMAP_RND_COMPAT_BITS_MIN 889 config ARCH_MMAP_RND_COMPAT_BITS_MIN
1114 int 890 int
1115 891
1116 config ARCH_MMAP_RND_COMPAT_BITS_MAX 892 config ARCH_MMAP_RND_COMPAT_BITS_MAX
1117 int 893 int
1118 894
1119 config ARCH_MMAP_RND_COMPAT_BITS_DEFAULT 895 config ARCH_MMAP_RND_COMPAT_BITS_DEFAULT
1120 int 896 int
1121 897
1122 config ARCH_MMAP_RND_COMPAT_BITS 898 config ARCH_MMAP_RND_COMPAT_BITS
1123 int "Number of bits to use for ASLR o 899 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 900 range ARCH_MMAP_RND_COMPAT_BITS_MIN ARCH_MMAP_RND_COMPAT_BITS_MAX
1125 default ARCH_MMAP_RND_COMPAT_BITS_DEF 901 default ARCH_MMAP_RND_COMPAT_BITS_DEFAULT if ARCH_MMAP_RND_COMPAT_BITS_DEFAULT
1126 default ARCH_MMAP_RND_COMPAT_BITS_MIN 902 default ARCH_MMAP_RND_COMPAT_BITS_MIN
1127 depends on HAVE_ARCH_MMAP_RND_COMPAT_ 903 depends on HAVE_ARCH_MMAP_RND_COMPAT_BITS
1128 help 904 help
1129 This value can be used to select th 905 This value can be used to select the number of bits to use to
1130 determine the random offset to the 906 determine the random offset to the base address of vma regions
1131 resulting from mmap allocations for 907 resulting from mmap allocations for compatible applications This
1132 value will be bounded by the archit 908 value will be bounded by the architecture's minimum and maximum
1133 supported values. 909 supported values.
1134 910
1135 This value can be changed after boo 911 This value can be changed after boot using the
1136 /proc/sys/vm/mmap_rnd_compat_bits t 912 /proc/sys/vm/mmap_rnd_compat_bits tunable
1137 913
1138 config HAVE_ARCH_COMPAT_MMAP_BASES 914 config HAVE_ARCH_COMPAT_MMAP_BASES
1139 bool 915 bool
1140 help 916 help
1141 This allows 64bit applications to i 917 This allows 64bit applications to invoke 32-bit mmap() syscall
1142 and vice-versa 32-bit applications 918 and vice-versa 32-bit applications to call 64-bit mmap().
1143 Required for applications doing dif 919 Required for applications doing different bitness syscalls.
1144 920
1145 config HAVE_PAGE_SIZE_4KB <<
1146 bool <<
1147 <<
1148 config HAVE_PAGE_SIZE_8KB <<
1149 bool <<
1150 <<
1151 config HAVE_PAGE_SIZE_16KB <<
1152 bool <<
1153 <<
1154 config HAVE_PAGE_SIZE_32KB <<
1155 bool <<
1156 <<
1157 config HAVE_PAGE_SIZE_64KB <<
1158 bool <<
1159 <<
1160 config HAVE_PAGE_SIZE_256KB <<
1161 bool <<
1162 <<
1163 choice <<
1164 prompt "MMU page size" <<
1165 <<
1166 config PAGE_SIZE_4KB <<
1167 bool "4KiB pages" <<
1168 depends on HAVE_PAGE_SIZE_4KB <<
1169 help <<
1170 This option select the standard 4Ki <<
1171 available option on many architectu <<
1172 minimize memory consumption and is <<
1173 memory systems. <<
1174 Some software that is written for x <<
1175 assumptions about the page size and <<
1176 <<
1177 config PAGE_SIZE_8KB <<
1178 bool "8KiB pages" <<
1179 depends on HAVE_PAGE_SIZE_8KB <<
1180 help <<
1181 This option is the only supported p <<
1182 processors, and can be slightly fas <<
1183 <<
1184 config PAGE_SIZE_16KB <<
1185 bool "16KiB pages" <<
1186 depends on HAVE_PAGE_SIZE_16KB <<
1187 help <<
1188 This option is usually a good compr <<
1189 consumption and performance for typ <<
1190 workloads, often saving a level of <<
1191 to 4KB pages as well as reducing TL <<
1192 per-page operations in the kernel a <<
1193 page cache. <<
1194 <<
1195 config PAGE_SIZE_32KB <<
1196 bool "32KiB pages" <<
1197 depends on HAVE_PAGE_SIZE_32KB <<
1198 help <<
1199 Using 32KiB page size will result i <<
1200 kernel at the price of higher memor <<
1201 16KiB pages. This option is availa <<
1202 Note that you will need a suitable <<
1203 support this. <<
1204 <<
1205 config PAGE_SIZE_64KB <<
1206 bool "64KiB pages" <<
1207 depends on HAVE_PAGE_SIZE_64KB <<
1208 help <<
1209 Using 64KiB page size will result i <<
1210 kernel at the price of much higher <<
1211 4KiB or 16KiB pages. <<
1212 This is not suitable for general-pu <<
1213 better performance may be worth the <<
1214 supercomputing or database applicat <<
1215 large in-memory data rather than sm <<
1216 <<
1217 config PAGE_SIZE_256KB <<
1218 bool "256KiB pages" <<
1219 depends on HAVE_PAGE_SIZE_256KB <<
1220 help <<
1221 256KiB pages have little practical <<
1222 memory usage. The kernel will only <<
1223 that have been compiled with '-zmax <<
1224 (the default is 64KiB or 4KiB on mo <<
1225 <<
1226 endchoice <<
1227 <<
1228 config PAGE_SIZE_LESS_THAN_64KB <<
1229 def_bool y <<
1230 depends on !PAGE_SIZE_64KB <<
1231 depends on PAGE_SIZE_LESS_THAN_256KB <<
1232 <<
1233 config PAGE_SIZE_LESS_THAN_256KB <<
1234 def_bool y <<
1235 depends on !PAGE_SIZE_256KB <<
1236 <<
1237 config PAGE_SHIFT <<
1238 int <<
1239 default 12 if PAGE_SIZE_4KB <<
1240 default 13 if PAGE_SIZE_8KB <<
1241 default 14 if PAGE_SIZE_16KB <<
1242 default 15 if PAGE_SIZE_32KB <<
1243 default 16 if PAGE_SIZE_64KB <<
1244 default 18 if PAGE_SIZE_256KB <<
1245 <<
1246 # This allows to use a set of generic functio 921 # This allows to use a set of generic functions to determine mmap base
1247 # address by giving priority to top-down sche 922 # address by giving priority to top-down scheme only if the process
1248 # is not in legacy mode (compat task, unlimit 923 # is not in legacy mode (compat task, unlimited stack size or
1249 # sysctl_legacy_va_layout). 924 # sysctl_legacy_va_layout).
1250 # Architecture that selects this option can p 925 # Architecture that selects this option can provide its own version of:
1251 # - STACK_RND_MASK 926 # - STACK_RND_MASK
1252 config ARCH_WANT_DEFAULT_TOPDOWN_MMAP_LAYOUT 927 config ARCH_WANT_DEFAULT_TOPDOWN_MMAP_LAYOUT
1253 bool 928 bool
1254 depends on MMU 929 depends on MMU
1255 select ARCH_HAS_ELF_RANDOMIZE 930 select ARCH_HAS_ELF_RANDOMIZE
1256 931
1257 config HAVE_OBJTOOL <<
1258 bool <<
1259 <<
1260 config HAVE_JUMP_LABEL_HACK <<
1261 bool <<
1262 <<
1263 config HAVE_NOINSTR_HACK <<
1264 bool <<
1265 <<
1266 config HAVE_NOINSTR_VALIDATION <<
1267 bool <<
1268 <<
1269 config HAVE_UACCESS_VALIDATION <<
1270 bool <<
1271 select OBJTOOL <<
1272 <<
1273 config HAVE_STACK_VALIDATION 932 config HAVE_STACK_VALIDATION
1274 bool 933 bool
1275 help 934 help
1276 Architecture supports objtool compi !! 935 Architecture supports the 'objtool check' host tool command, which
1277 validation. !! 936 performs compile-time stack metadata validation.
1278 937
1279 config HAVE_RELIABLE_STACKTRACE 938 config HAVE_RELIABLE_STACKTRACE
1280 bool 939 bool
1281 help 940 help
1282 Architecture has either save_stack_ 941 Architecture has either save_stack_trace_tsk_reliable() or
1283 arch_stack_walk_reliable() function 942 arch_stack_walk_reliable() function which only returns a stack trace
1284 if it can guarantee the trace is re 943 if it can guarantee the trace is reliable.
1285 944
1286 config HAVE_ARCH_HASH 945 config HAVE_ARCH_HASH
1287 bool 946 bool
1288 default n 947 default n
1289 help 948 help
1290 If this is set, the architecture pr 949 If this is set, the architecture provides an <asm/hash.h>
1291 file which provides platform-specif 950 file which provides platform-specific implementations of some
1292 functions in <linux/hash.h> or fs/n 951 functions in <linux/hash.h> or fs/namei.c.
1293 952
1294 config HAVE_ARCH_NVRAM_OPS 953 config HAVE_ARCH_NVRAM_OPS
1295 bool 954 bool
1296 955
1297 config ISA_BUS_API 956 config ISA_BUS_API
1298 def_bool ISA 957 def_bool ISA
1299 958
1300 # 959 #
1301 # ABI hall of shame 960 # ABI hall of shame
1302 # 961 #
1303 config CLONE_BACKWARDS 962 config CLONE_BACKWARDS
1304 bool 963 bool
1305 help 964 help
1306 Architecture has tls passed as the 965 Architecture has tls passed as the 4th argument of clone(2),
1307 not the 5th one. 966 not the 5th one.
1308 967
1309 config CLONE_BACKWARDS2 968 config CLONE_BACKWARDS2
1310 bool 969 bool
1311 help 970 help
1312 Architecture has the first two argu 971 Architecture has the first two arguments of clone(2) swapped.
1313 972
1314 config CLONE_BACKWARDS3 973 config CLONE_BACKWARDS3
1315 bool 974 bool
1316 help 975 help
1317 Architecture has tls passed as the 976 Architecture has tls passed as the 3rd argument of clone(2),
1318 not the 5th one. 977 not the 5th one.
1319 978
1320 config ODD_RT_SIGACTION 979 config ODD_RT_SIGACTION
1321 bool 980 bool
1322 help 981 help
1323 Architecture has unusual rt_sigacti 982 Architecture has unusual rt_sigaction(2) arguments
1324 983
1325 config OLD_SIGSUSPEND 984 config OLD_SIGSUSPEND
1326 bool 985 bool
1327 help 986 help
1328 Architecture has old sigsuspend(2) 987 Architecture has old sigsuspend(2) syscall, of one-argument variety
1329 988
1330 config OLD_SIGSUSPEND3 989 config OLD_SIGSUSPEND3
1331 bool 990 bool
1332 help 991 help
1333 Even weirder antique ABI - three-ar 992 Even weirder antique ABI - three-argument sigsuspend(2)
1334 993
1335 config OLD_SIGACTION 994 config OLD_SIGACTION
1336 bool 995 bool
1337 help 996 help
1338 Architecture has old sigaction(2) s 997 Architecture has old sigaction(2) syscall. Nope, not the same
1339 as OLD_SIGSUSPEND | OLD_SIGSUSPEND3 998 as OLD_SIGSUSPEND | OLD_SIGSUSPEND3 - alpha has sigsuspend(2),
1340 but fairly different variant of sig 999 but fairly different variant of sigaction(2), thanks to OSF/1
1341 compatibility... 1000 compatibility...
1342 1001
1343 config COMPAT_OLD_SIGACTION 1002 config COMPAT_OLD_SIGACTION
1344 bool 1003 bool
1345 1004
1346 config COMPAT_32BIT_TIME 1005 config COMPAT_32BIT_TIME
1347 bool "Provide system calls for 32-bit 1006 bool "Provide system calls for 32-bit time_t"
1348 default !64BIT || COMPAT 1007 default !64BIT || COMPAT
1349 help 1008 help
1350 This enables 32 bit time_t support 1009 This enables 32 bit time_t support in addition to 64 bit time_t support.
1351 This is relevant on all 32-bit arch 1010 This is relevant on all 32-bit architectures, and 64-bit architectures
1352 as part of compat syscall handling. 1011 as part of compat syscall handling.
1353 1012
1354 config ARCH_NO_PREEMPT 1013 config ARCH_NO_PREEMPT
1355 bool 1014 bool
1356 1015
1357 config ARCH_SUPPORTS_RT 1016 config ARCH_SUPPORTS_RT
1358 bool 1017 bool
1359 1018
1360 config CPU_NO_EFFICIENT_FFS 1019 config CPU_NO_EFFICIENT_FFS
1361 def_bool n 1020 def_bool n
1362 1021
1363 config HAVE_ARCH_VMAP_STACK 1022 config HAVE_ARCH_VMAP_STACK
1364 def_bool n 1023 def_bool n
1365 help 1024 help
1366 An arch should select this symbol i 1025 An arch should select this symbol if it can support kernel stacks
1367 in vmalloc space. This means: 1026 in vmalloc space. This means:
1368 1027
1369 - vmalloc space must be large enoug 1028 - vmalloc space must be large enough to hold many kernel stacks.
1370 This may rule out many 32-bit arc 1029 This may rule out many 32-bit architectures.
1371 1030
1372 - Stacks in vmalloc space need to w 1031 - Stacks in vmalloc space need to work reliably. For example, if
1373 vmap page tables are created on d 1032 vmap page tables are created on demand, either this mechanism
1374 needs to work while the stack poi 1033 needs to work while the stack points to a virtual address with
1375 unpopulated page tables or arch c 1034 unpopulated page tables or arch code (switch_to() and switch_mm(),
1376 most likely) needs to ensure that 1035 most likely) needs to ensure that the stack's page table entries
1377 are populated before running on a 1036 are populated before running on a possibly unpopulated stack.
1378 1037
1379 - If the stack overflows into a gua 1038 - If the stack overflows into a guard page, something reasonable
1380 should happen. The definition of 1039 should happen. The definition of "reasonable" is flexible, but
1381 instantly rebooting without loggi 1040 instantly rebooting without logging anything would be unfriendly.
1382 1041
1383 config VMAP_STACK 1042 config VMAP_STACK
1384 default y 1043 default y
1385 bool "Use a virtually-mapped stack" 1044 bool "Use a virtually-mapped stack"
1386 depends on HAVE_ARCH_VMAP_STACK 1045 depends on HAVE_ARCH_VMAP_STACK
1387 depends on !KASAN || KASAN_HW_TAGS || 1046 depends on !KASAN || KASAN_HW_TAGS || KASAN_VMALLOC
1388 help 1047 help
1389 Enable this if you want the use vir 1048 Enable this if you want the use virtually-mapped kernel stacks
1390 with guard pages. This causes kern 1049 with guard pages. This causes kernel stack overflows to be
1391 caught immediately rather than caus 1050 caught immediately rather than causing difficult-to-diagnose
1392 corruption. 1051 corruption.
1393 1052
1394 To use this with software KASAN mod 1053 To use this with software KASAN modes, the architecture must support
1395 backing virtual mappings with real 1054 backing virtual mappings with real shadow memory, and KASAN_VMALLOC
1396 must be enabled. 1055 must be enabled.
1397 1056
1398 config HAVE_ARCH_RANDOMIZE_KSTACK_OFFSET <<
1399 def_bool n <<
1400 help <<
1401 An arch should select this symbol i <<
1402 offset randomization with calls to <<
1403 during syscall entry and choose_ran <<
1404 syscall exit. Careful removal of -f <<
1405 -fstack-protector should also be ap <<
1406 closely examined, as the artificial <<
1407 to the compiler, so it will attempt <<
1408 of the static branch state. <<
1409 <<
1410 config RANDOMIZE_KSTACK_OFFSET <<
1411 bool "Support for randomizing kernel <<
1412 default y <<
1413 depends on HAVE_ARCH_RANDOMIZE_KSTACK <<
1414 depends on INIT_STACK_NONE || !CC_IS_ <<
1415 help <<
1416 The kernel stack offset can be rand <<
1417 roughly 5 bits of entropy, frustrat <<
1418 attacks that depend on stack addres <<
1419 cross-syscall address exposures. <<
1420 <<
1421 The feature is controlled via the " <<
1422 kernel boot param, and if turned of <<
1423 of static branches (see JUMP_LABEL) <<
1424 <<
1425 If unsure, say Y. <<
1426 <<
1427 config RANDOMIZE_KSTACK_OFFSET_DEFAULT <<
1428 bool "Default state of kernel stack o <<
1429 depends on RANDOMIZE_KSTACK_OFFSET <<
1430 help <<
1431 Kernel stack offset randomization i <<
1432 "randomize_kstack_offset=on/off", a <<
1433 boot state. <<
1434 <<
1435 config ARCH_OPTIONAL_KERNEL_RWX 1057 config ARCH_OPTIONAL_KERNEL_RWX
1436 def_bool n 1058 def_bool n
1437 1059
1438 config ARCH_OPTIONAL_KERNEL_RWX_DEFAULT 1060 config ARCH_OPTIONAL_KERNEL_RWX_DEFAULT
1439 def_bool n 1061 def_bool n
1440 1062
1441 config ARCH_HAS_STRICT_KERNEL_RWX 1063 config ARCH_HAS_STRICT_KERNEL_RWX
1442 def_bool n 1064 def_bool n
1443 1065
1444 config STRICT_KERNEL_RWX 1066 config STRICT_KERNEL_RWX
1445 bool "Make kernel text and rodata rea 1067 bool "Make kernel text and rodata read-only" if ARCH_OPTIONAL_KERNEL_RWX
1446 depends on ARCH_HAS_STRICT_KERNEL_RWX 1068 depends on ARCH_HAS_STRICT_KERNEL_RWX
1447 default !ARCH_OPTIONAL_KERNEL_RWX || 1069 default !ARCH_OPTIONAL_KERNEL_RWX || ARCH_OPTIONAL_KERNEL_RWX_DEFAULT
1448 help 1070 help
1449 If this is set, kernel text and rod 1071 If this is set, kernel text and rodata memory will be made read-only,
1450 and non-text memory will be made no 1072 and non-text memory will be made non-executable. This provides
1451 protection against certain security 1073 protection against certain security exploits (e.g. executing the heap
1452 or modifying text) 1074 or modifying text)
1453 1075
1454 These features are considered stand 1076 These features are considered standard security practice these days.
1455 You should say Y here in almost all 1077 You should say Y here in almost all cases.
1456 1078
1457 config ARCH_HAS_STRICT_MODULE_RWX 1079 config ARCH_HAS_STRICT_MODULE_RWX
1458 def_bool n 1080 def_bool n
1459 1081
1460 config STRICT_MODULE_RWX 1082 config STRICT_MODULE_RWX
1461 bool "Set loadable kernel module data 1083 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 1084 depends on ARCH_HAS_STRICT_MODULE_RWX && MODULES
1463 default !ARCH_OPTIONAL_KERNEL_RWX || 1085 default !ARCH_OPTIONAL_KERNEL_RWX || ARCH_OPTIONAL_KERNEL_RWX_DEFAULT
1464 help 1086 help
1465 If this is set, module text and rod 1087 If this is set, module text and rodata memory will be made read-only,
1466 and non-text memory will be made no 1088 and non-text memory will be made non-executable. This provides
1467 protection against certain security 1089 protection against certain security exploits (e.g. writing to text)
1468 1090
1469 # select if the architecture provides an asm/ 1091 # select if the architecture provides an asm/dma-direct.h header
1470 config ARCH_HAS_PHYS_TO_DMA 1092 config ARCH_HAS_PHYS_TO_DMA
1471 bool 1093 bool
1472 1094
1473 config HAVE_ARCH_COMPILER_H 1095 config HAVE_ARCH_COMPILER_H
1474 bool 1096 bool
1475 help 1097 help
1476 An architecture can select this if 1098 An architecture can select this if it provides an
1477 asm/compiler.h header that should b 1099 asm/compiler.h header that should be included after
1478 linux/compiler-*.h in order to over 1100 linux/compiler-*.h in order to override macro definitions that those
1479 headers generally provide. 1101 headers generally provide.
1480 1102
1481 config HAVE_ARCH_PREL32_RELOCATIONS 1103 config HAVE_ARCH_PREL32_RELOCATIONS
1482 bool 1104 bool
1483 help 1105 help
1484 May be selected by an architecture 1106 May be selected by an architecture if it supports place-relative
1485 32-bit relocations, both in the too 1107 32-bit relocations, both in the toolchain and in the module loader,
1486 in which case relative references c 1108 in which case relative references can be used in special sections
1487 for PCI fixup, initcalls etc which 1109 for PCI fixup, initcalls etc which are only half the size on 64 bit
1488 architectures, and don't require ru 1110 architectures, and don't require runtime relocation on relocatable
1489 kernels. 1111 kernels.
1490 1112
1491 config ARCH_USE_MEMREMAP_PROT 1113 config ARCH_USE_MEMREMAP_PROT
1492 bool 1114 bool
1493 1115
1494 config LOCK_EVENT_COUNTS 1116 config LOCK_EVENT_COUNTS
1495 bool "Locking event counts collection 1117 bool "Locking event counts collection"
1496 depends on DEBUG_FS 1118 depends on DEBUG_FS
1497 help 1119 help
1498 Enable light-weight counting of var 1120 Enable light-weight counting of various locking related events
1499 in the system with minimal performa 1121 in the system with minimal performance impact. This reduces
1500 the chance of application behavior 1122 the chance of application behavior change because of timing
1501 differences. The counts are reporte 1123 differences. The counts are reported via debugfs.
1502 1124
1503 # Select if the architecture has support for 1125 # Select if the architecture has support for applying RELR relocations.
1504 config ARCH_HAS_RELR 1126 config ARCH_HAS_RELR
1505 bool 1127 bool
1506 1128
1507 config RELR 1129 config RELR
1508 bool "Use RELR relocation packing" 1130 bool "Use RELR relocation packing"
1509 depends on ARCH_HAS_RELR && TOOLS_SUP 1131 depends on ARCH_HAS_RELR && TOOLS_SUPPORT_RELR
1510 default y 1132 default y
1511 help 1133 help
1512 Store the kernel's dynamic relocati 1134 Store the kernel's dynamic relocations in the RELR relocation packing
1513 format. Requires a compatible linke 1135 format. Requires a compatible linker (LLD supports this feature), as
1514 well as compatible NM and OBJCOPY u 1136 well as compatible NM and OBJCOPY utilities (llvm-nm and llvm-objcopy
1515 are compatible). 1137 are compatible).
1516 1138
1517 config ARCH_HAS_MEM_ENCRYPT 1139 config ARCH_HAS_MEM_ENCRYPT
1518 bool 1140 bool
1519 1141
1520 config ARCH_HAS_CC_PLATFORM <<
1521 bool <<
1522 <<
1523 config HAVE_SPARSE_SYSCALL_NR 1142 config HAVE_SPARSE_SYSCALL_NR
1524 bool !! 1143 bool
1525 help !! 1144 help
1526 An architecture should select this !! 1145 An architecture should select this if its syscall numbering is sparse
1527 to save space. For example, MIPS ar 1146 to save space. For example, MIPS architecture has a syscall array with
1528 entries at 4000, 5000 and 6000 loca 1147 entries at 4000, 5000 and 6000 locations. This option turns on syscall
1529 related optimizations for a given a 1148 related optimizations for a given architecture.
1530 1149
1531 config ARCH_HAS_VDSO_DATA 1150 config ARCH_HAS_VDSO_DATA
1532 bool 1151 bool
1533 1152
1534 config HAVE_STATIC_CALL 1153 config HAVE_STATIC_CALL
1535 bool 1154 bool
1536 1155
1537 config HAVE_STATIC_CALL_INLINE 1156 config HAVE_STATIC_CALL_INLINE
1538 bool 1157 bool
1539 depends on HAVE_STATIC_CALL 1158 depends on HAVE_STATIC_CALL
1540 select OBJTOOL <<
1541 1159
1542 config HAVE_PREEMPT_DYNAMIC 1160 config HAVE_PREEMPT_DYNAMIC
1543 bool 1161 bool
1544 <<
1545 config HAVE_PREEMPT_DYNAMIC_CALL <<
1546 bool <<
1547 depends on HAVE_STATIC_CALL 1162 depends on HAVE_STATIC_CALL
1548 select HAVE_PREEMPT_DYNAMIC !! 1163 depends on GENERIC_ENTRY
1549 help <<
1550 An architecture should select this <<
1551 model being selected at boot time u <<
1552 <<
1553 Where an architecture selects HAVE_ <<
1554 preemption function will be patched <<
1555 <<
1556 Where an architecture does not sele <<
1557 call to a preemption function will <<
1558 trampoline will be patched. <<
1559 <<
1560 It is strongly advised to support i <<
1561 overhead. <<
1562 <<
1563 config HAVE_PREEMPT_DYNAMIC_KEY <<
1564 bool <<
1565 depends on HAVE_ARCH_JUMP_LABEL <<
1566 select HAVE_PREEMPT_DYNAMIC <<
1567 help 1164 help
1568 An architecture should select this !! 1165 Select this if the architecture support boot time preempt setting
1569 model being selected at boot time u !! 1166 on top of static calls. It is strongly advised to support inline
1570 !! 1167 static call to avoid any overhead.
1571 Each preemption function will be gi <<
1572 static key. This should have slight <<
1573 static calls, as this effectively i <<
1574 start of its callee. This may avoid <<
1575 integrate better with CFI schemes. <<
1576 <<
1577 This will have greater overhead tha <<
1578 the call to the preemption function <<
1579 1168
1580 config ARCH_WANT_LD_ORPHAN_WARN 1169 config ARCH_WANT_LD_ORPHAN_WARN
1581 bool 1170 bool
1582 help 1171 help
1583 An arch should select this symbol o 1172 An arch should select this symbol once all linker sections are explicitly
1584 included, size-asserted, or discard 1173 included, size-asserted, or discarded in the linker scripts. This is
1585 important because we never want exp 1174 important because we never want expected sections to be placed heuristically
1586 by the linker, since the locations 1175 by the linker, since the locations of such sections can change between linker
1587 versions. 1176 versions.
1588 1177
1589 config HAVE_ARCH_PFN_VALID 1178 config HAVE_ARCH_PFN_VALID
1590 bool 1179 bool
1591 1180
1592 config ARCH_SUPPORTS_DEBUG_PAGEALLOC 1181 config ARCH_SUPPORTS_DEBUG_PAGEALLOC
1593 bool 1182 bool
1594 1183
1595 config ARCH_SUPPORTS_PAGE_TABLE_CHECK <<
1596 bool <<
1597 <<
1598 config ARCH_SPLIT_ARG64 1184 config ARCH_SPLIT_ARG64
1599 bool 1185 bool
1600 help 1186 help
1601 If a 32-bit architecture requires 6 !! 1187 If a 32-bit architecture requires 64-bit arguments to be split into
1602 pairs of 32-bit arguments, select t !! 1188 pairs of 32-bit arguments, select this option.
1603 1189
1604 config ARCH_HAS_ELFCORE_COMPAT 1190 config ARCH_HAS_ELFCORE_COMPAT
1605 bool 1191 bool
1606 1192
1607 config ARCH_HAS_PARANOID_L1D_FLUSH <<
1608 bool <<
1609 <<
1610 config ARCH_HAVE_TRACE_MMIO_ACCESS <<
1611 bool <<
1612 <<
1613 config DYNAMIC_SIGFRAME <<
1614 bool <<
1615 <<
1616 # Select, if arch has a named attribute group <<
1617 config HAVE_ARCH_NODE_DEV_GROUP <<
1618 bool <<
1619 <<
1620 config ARCH_HAS_HW_PTE_YOUNG <<
1621 bool <<
1622 help <<
1623 Architectures that select this opti <<
1624 accessed bit in PTE entries when us <<
1625 translations. Architectures that re <<
1626 this option and override arch_has_h <<
1627 <<
1628 config ARCH_HAS_NONLEAF_PMD_YOUNG <<
1629 bool <<
1630 help <<
1631 Architectures that select this opti <<
1632 accessed bit in non-leaf PMD entrie <<
1633 address translations. Page table wa <<
1634 may use this capability to reduce t <<
1635 <<
1636 config ARCH_HAS_KERNEL_FPU_SUPPORT <<
1637 bool <<
1638 help <<
1639 Architectures that select this opti <<
1640 the kernel, as described in Documen <<
1641 <<
1642 source "kernel/gcov/Kconfig" 1193 source "kernel/gcov/Kconfig"
1643 1194
1644 source "scripts/gcc-plugins/Kconfig" 1195 source "scripts/gcc-plugins/Kconfig"
1645 <<
1646 config FUNCTION_ALIGNMENT_4B <<
1647 bool <<
1648 <<
1649 config FUNCTION_ALIGNMENT_8B <<
1650 bool <<
1651 <<
1652 config FUNCTION_ALIGNMENT_16B <<
1653 bool <<
1654 <<
1655 config FUNCTION_ALIGNMENT_32B <<
1656 bool <<
1657 <<
1658 config FUNCTION_ALIGNMENT_64B <<
1659 bool <<
1660 <<
1661 config FUNCTION_ALIGNMENT <<
1662 int <<
1663 default 64 if FUNCTION_ALIGNMENT_64B <<
1664 default 32 if FUNCTION_ALIGNMENT_32B <<
1665 default 16 if FUNCTION_ALIGNMENT_16B <<
1666 default 8 if FUNCTION_ALIGNMENT_8B <<
1667 default 4 if FUNCTION_ALIGNMENT_4B <<
1668 default 0 <<
1669 <<
1670 config CC_HAS_MIN_FUNCTION_ALIGNMENT <<
1671 # Detect availability of the GCC opti <<
1672 # guarantees minimal alignment for al <<
1673 # -falign-functions which the compile <<
1674 def_bool $(cc-option, -fmin-function- <<
1675 <<
1676 config CC_HAS_SANE_FUNCTION_ALIGNMENT <<
1677 # Set if the guaranteed alignment wit <<
1678 # available or extra care is required <<
1679 # strict alignment always, even with <<
1680 def_bool CC_HAS_MIN_FUNCTION_ALIGNMEN <<
1681 <<
1682 config ARCH_NEED_CMPXCHG_1_EMU <<
1683 bool <<
1684 1196
1685 endmenu 1197 endmenu
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