1 # SPDX-License-Identifier: GPL-2.0 1 # SPDX-License-Identifier: GPL-2.0
2 # 2 #
3 # General architecture dependent options 3 # General architecture dependent options
4 # 4 #
5 5
6 # 6 #
7 # Note: arch/$(SRCARCH)/Kconfig needs to be in 7 # Note: arch/$(SRCARCH)/Kconfig needs to be included first so that it can
8 # override the default values in this file. 8 # override the default values in this file.
9 # 9 #
10 source "arch/$(SRCARCH)/Kconfig" 10 source "arch/$(SRCARCH)/Kconfig"
11 11
12 config ARCH_CONFIGURES_CPU_MITIGATIONS !! 12 menu "General architecture-dependent options"
13 bool <<
14 13
15 if !ARCH_CONFIGURES_CPU_MITIGATIONS !! 14 config CRASH_CORE
16 config CPU_MITIGATIONS !! 15 bool
17 def_bool y <<
18 endif <<
19 16
20 # !! 17 config KEXEC_CORE
21 # Selected by architectures that need custom D !! 18 select CRASH_CORE
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 19 bool
28 20
29 menu "General architecture-dependent options" !! 21 config KEXEC_ELF
>> 22 bool
30 23
31 config ARCH_HAS_SUBPAGE_FAULTS !! 24 config HAVE_IMA_KEXEC
32 bool 25 bool
33 help <<
34 Select if the architecture can check <<
35 granularity (e.g. arm64 MTE). The pr <<
36 must be implemented. <<
37 26
38 config HOTPLUG_SMT 27 config HOTPLUG_SMT
39 bool 28 bool
40 29
41 config SMT_NUM_THREADS_DYNAMIC !! 30 config GENERIC_ENTRY
42 bool !! 31 bool
43 32
44 # Selected by HOTPLUG_CORE_SYNC_DEAD or HOTPLU !! 33 config OPROFILE
45 config HOTPLUG_CORE_SYNC !! 34 tristate "OProfile system profiling"
46 bool !! 35 depends on PROFILING
>> 36 depends on HAVE_OPROFILE
>> 37 select RING_BUFFER
>> 38 select RING_BUFFER_ALLOW_SWAP
>> 39 help
>> 40 OProfile is a profiling system capable of profiling the
>> 41 whole system, include the kernel, kernel modules, libraries,
>> 42 and applications.
47 43
48 # Basic CPU dead synchronization selected by a !! 44 If unsure, say N.
49 config HOTPLUG_CORE_SYNC_DEAD <<
50 bool <<
51 select HOTPLUG_CORE_SYNC <<
52 45
53 # Full CPU synchronization with alive state se !! 46 config OPROFILE_EVENT_MULTIPLEX
54 config HOTPLUG_CORE_SYNC_FULL !! 47 bool "OProfile multiplexing support (EXPERIMENTAL)"
55 bool !! 48 default n
56 select HOTPLUG_CORE_SYNC_DEAD if HOTPL !! 49 depends on OPROFILE && X86
57 select HOTPLUG_CORE_SYNC !! 50 help
>> 51 The number of hardware counters is limited. The multiplexing
>> 52 feature enables OProfile to gather more events than counters
>> 53 are provided by the hardware. This is realized by switching
>> 54 between events at a user specified time interval.
58 55
59 config HOTPLUG_SPLIT_STARTUP !! 56 If unsure, say N.
60 bool <<
61 select HOTPLUG_CORE_SYNC_FULL <<
62 57
63 config HOTPLUG_PARALLEL !! 58 config HAVE_OPROFILE
64 bool 59 bool
65 select HOTPLUG_SPLIT_STARTUP <<
66 60
67 config GENERIC_ENTRY !! 61 config OPROFILE_NMI_TIMER
68 bool !! 62 def_bool y
>> 63 depends on PERF_EVENTS && HAVE_PERF_EVENTS_NMI && !PPC64
69 64
70 config KPROBES 65 config KPROBES
71 bool "Kprobes" 66 bool "Kprobes"
>> 67 depends on MODULES
72 depends on HAVE_KPROBES 68 depends on HAVE_KPROBES
73 select KALLSYMS 69 select KALLSYMS
74 select EXECMEM <<
75 select NEED_TASKS_RCU <<
76 help 70 help
77 Kprobes allows you to trap at almost 71 Kprobes allows you to trap at almost any kernel address and
78 execute a callback function. regist 72 execute a callback function. register_kprobe() establishes
79 a probepoint and specifies the callb 73 a probepoint and specifies the callback. Kprobes is useful
80 for kernel debugging, non-intrusive 74 for kernel debugging, non-intrusive instrumentation and testing.
81 If in doubt, say "N". 75 If in doubt, say "N".
82 76
83 config JUMP_LABEL 77 config JUMP_LABEL
84 bool "Optimize very unlikely/likely br 78 bool "Optimize very unlikely/likely branches"
85 depends on HAVE_ARCH_JUMP_LABEL 79 depends on HAVE_ARCH_JUMP_LABEL
86 select OBJTOOL if HAVE_JUMP_LABEL_HACK !! 80 depends on CC_HAS_ASM_GOTO
87 help 81 help
88 This option enables a transparent br !! 82 This option enables a transparent branch optimization that
89 makes certain almost-always-true or !! 83 makes certain almost-always-true or almost-always-false branch
90 conditions even cheaper to execute w !! 84 conditions even cheaper to execute within the kernel.
91 !! 85
92 Certain performance-sensitive kernel !! 86 Certain performance-sensitive kernel code, such as trace points,
93 scheduler functionality, networking !! 87 scheduler functionality, networking code and KVM have such
94 branches and include support for thi !! 88 branches and include support for this optimization technique.
95 !! 89
96 If it is detected that the compiler !! 90 If it is detected that the compiler has support for "asm goto",
97 the kernel will compile such branche !! 91 the kernel will compile such branches with just a nop
98 instruction. When the condition flag !! 92 instruction. When the condition flag is toggled to true, the
99 nop will be converted to a jump inst !! 93 nop will be converted to a jump instruction to execute the
100 conditional block of instructions. !! 94 conditional block of instructions.
101 !! 95
102 This technique lowers overhead and s !! 96 This technique lowers overhead and stress on the branch prediction
103 of the processor and generally makes !! 97 of the processor and generally makes the kernel faster. The update
104 of the condition is slower, but thos !! 98 of the condition is slower, but those are always very rare.
105 99
106 ( On 32-bit x86, the necessary optio !! 100 ( On 32-bit x86, the necessary options added to the compiler
107 flags may increase the size of the !! 101 flags may increase the size of the kernel slightly. )
108 102
109 config STATIC_KEYS_SELFTEST 103 config STATIC_KEYS_SELFTEST
110 bool "Static key selftest" 104 bool "Static key selftest"
111 depends on JUMP_LABEL 105 depends on JUMP_LABEL
112 help 106 help
113 Boot time self-test of the branch pa 107 Boot time self-test of the branch patching code.
114 108
115 config STATIC_CALL_SELFTEST <<
116 bool "Static call selftest" <<
117 depends on HAVE_STATIC_CALL <<
118 help <<
119 Boot time self-test of the call patc <<
120 <<
121 config OPTPROBES 109 config OPTPROBES
122 def_bool y 110 def_bool y
123 depends on KPROBES && HAVE_OPTPROBES 111 depends on KPROBES && HAVE_OPTPROBES
124 select NEED_TASKS_RCU !! 112 select TASKS_RCU if PREEMPTION
125 113
126 config KPROBES_ON_FTRACE 114 config KPROBES_ON_FTRACE
127 def_bool y 115 def_bool y
128 depends on KPROBES && HAVE_KPROBES_ON_ 116 depends on KPROBES && HAVE_KPROBES_ON_FTRACE
129 depends on DYNAMIC_FTRACE_WITH_REGS 117 depends on DYNAMIC_FTRACE_WITH_REGS
130 help 118 help
131 If function tracer is enabled and th !! 119 If function tracer is enabled and the arch supports full
132 passing of pt_regs to function traci !! 120 passing of pt_regs to function tracing, then kprobes can
133 optimize on top of function tracing. !! 121 optimize on top of function tracing.
134 122
135 config UPROBES 123 config UPROBES
136 def_bool n 124 def_bool n
137 depends on ARCH_SUPPORTS_UPROBES 125 depends on ARCH_SUPPORTS_UPROBES
138 help 126 help
139 Uprobes is the user-space counterpar 127 Uprobes is the user-space counterpart to kprobes: they
140 enable instrumentation applications 128 enable instrumentation applications (such as 'perf probe')
141 to establish unintrusive probes in u 129 to establish unintrusive probes in user-space binaries and
142 libraries, by executing handler func 130 libraries, by executing handler functions when the probes
143 are hit by user-space applications. 131 are hit by user-space applications.
144 132
145 ( These probes come in the form of s 133 ( These probes come in the form of single-byte breakpoints,
146 managed by the kernel and kept tra 134 managed by the kernel and kept transparent to the probed
147 application. ) 135 application. )
148 136
149 config HAVE_64BIT_ALIGNED_ACCESS <<
150 def_bool 64BIT && !HAVE_EFFICIENT_UNAL <<
151 help <<
152 Some architectures require 64 bit ac <<
153 aligned, which also requires structs <<
154 to be 64 bit aligned too. This inclu <<
155 architectures which can do 64 bit ac <<
156 architectures without unaligned acce <<
157 <<
158 This symbol should be selected by an <<
159 accesses are required to be 64 bit a <<
160 though it is not a 64 bit architectu <<
161 <<
162 See Documentation/core-api/unaligned <<
163 more information on the topic of una <<
164 <<
165 config HAVE_EFFICIENT_UNALIGNED_ACCESS 137 config HAVE_EFFICIENT_UNALIGNED_ACCESS
166 bool 138 bool
167 help 139 help
168 Some architectures are unable to per 140 Some architectures are unable to perform unaligned accesses
169 without the use of get_unaligned/put 141 without the use of get_unaligned/put_unaligned. Others are
170 unable to perform such accesses effi 142 unable to perform such accesses efficiently (e.g. trap on
171 unaligned access and require fixing 143 unaligned access and require fixing it up in the exception
172 handler.) 144 handler.)
173 145
174 This symbol should be selected by an 146 This symbol should be selected by an architecture if it can
175 perform unaligned accesses efficient 147 perform unaligned accesses efficiently to allow different
176 code paths to be selected for these 148 code paths to be selected for these cases. Some network
177 drivers, for example, could opt to n 149 drivers, for example, could opt to not fix up alignment
178 problems with received packets if do 150 problems with received packets if doing so would not help
179 much. 151 much.
180 152
181 See Documentation/core-api/unaligned 153 See Documentation/core-api/unaligned-memory-access.rst for more
182 information on the topic of unaligne 154 information on the topic of unaligned memory accesses.
183 155
184 config ARCH_USE_BUILTIN_BSWAP 156 config ARCH_USE_BUILTIN_BSWAP
185 bool 157 bool
186 help 158 help
187 Modern versions of GCC (since 4.4) h !! 159 Modern versions of GCC (since 4.4) have builtin functions
188 for handling byte-swapping. Using th !! 160 for handling byte-swapping. Using these, instead of the old
189 inline assembler that the architectu !! 161 inline assembler that the architecture code provides in the
190 __arch_bswapXX() macros, allows the !! 162 __arch_bswapXX() macros, allows the compiler to see what's
191 happening and offers more opportunit !! 163 happening and offers more opportunity for optimisation. In
192 particular, the compiler will be abl !! 164 particular, the compiler will be able to combine the byteswap
193 with a nearby load or store and use !! 165 with a nearby load or store and use load-and-swap or
194 store-and-swap instructions if the a !! 166 store-and-swap instructions if the architecture has them. It
195 should almost *never* result in code !! 167 should almost *never* result in code which is worse than the
196 hand-coded assembler in <asm/swab.h> !! 168 hand-coded assembler in <asm/swab.h>. But just in case it
197 does, the use of the builtins is opt !! 169 does, the use of the builtins is optional.
198 !! 170
199 Any architecture with load-and-swap !! 171 Any architecture with load-and-swap or store-and-swap
200 instructions should set this. And it !! 172 instructions should set this. And it shouldn't hurt to set it
201 on architectures that don't have suc !! 173 on architectures that don't have such instructions.
202 174
203 config KRETPROBES 175 config KRETPROBES
204 def_bool y 176 def_bool y
205 depends on KPROBES && (HAVE_KRETPROBES !! 177 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 <<
212 178
213 config USER_RETURN_NOTIFIER 179 config USER_RETURN_NOTIFIER
214 bool 180 bool
215 depends on HAVE_USER_RETURN_NOTIFIER 181 depends on HAVE_USER_RETURN_NOTIFIER
216 help 182 help
217 Provide a kernel-internal notificati 183 Provide a kernel-internal notification when a cpu is about to
218 switch to user mode. 184 switch to user mode.
219 185
220 config HAVE_IOREMAP_PROT 186 config HAVE_IOREMAP_PROT
221 bool 187 bool
222 188
223 config HAVE_KPROBES 189 config HAVE_KPROBES
224 bool 190 bool
225 191
226 config HAVE_KRETPROBES 192 config HAVE_KRETPROBES
227 bool 193 bool
228 194
229 config HAVE_OPTPROBES 195 config HAVE_OPTPROBES
230 bool 196 bool
231 197
232 config HAVE_KPROBES_ON_FTRACE 198 config HAVE_KPROBES_ON_FTRACE
233 bool 199 bool
234 200
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 201 config HAVE_FUNCTION_ERROR_INJECTION
244 bool 202 bool
245 203
246 config HAVE_NMI 204 config HAVE_NMI
247 bool 205 bool
248 206
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 # 207 #
259 # An arch should select this if it provides al 208 # An arch should select this if it provides all these things:
260 # 209 #
261 # task_pt_regs() in asm/process 210 # task_pt_regs() in asm/processor.h or asm/ptrace.h
262 # arch_has_single_step() if there is ha 211 # arch_has_single_step() if there is hardware single-step support
263 # arch_has_block_step() if there is ha 212 # arch_has_block_step() if there is hardware block-step support
264 # asm/syscall.h supplying asm- 213 # asm/syscall.h supplying asm-generic/syscall.h interface
265 # linux/regset.h user_regset in 214 # linux/regset.h user_regset interfaces
266 # CORE_DUMP_USE_REGSET #define'd in l 215 # CORE_DUMP_USE_REGSET #define'd in linux/elf.h
267 # TIF_SYSCALL_TRACE calls ptrace_r !! 216 # TIF_SYSCALL_TRACE calls tracehook_report_syscall_{entry,exit}
268 # TIF_NOTIFY_RESUME calls resume_u !! 217 # TIF_NOTIFY_RESUME calls tracehook_notify_resume()
>> 218 # signal delivery calls tracehook_signal_handler()
269 # 219 #
270 config HAVE_ARCH_TRACEHOOK 220 config HAVE_ARCH_TRACEHOOK
271 bool 221 bool
272 222
273 config HAVE_DMA_CONTIGUOUS 223 config HAVE_DMA_CONTIGUOUS
274 bool 224 bool
275 225
276 config GENERIC_SMP_IDLE_THREAD 226 config GENERIC_SMP_IDLE_THREAD
277 bool 227 bool
278 228
279 config GENERIC_IDLE_POLL_SETUP 229 config GENERIC_IDLE_POLL_SETUP
280 bool 230 bool
281 231
282 config ARCH_HAS_FORTIFY_SOURCE 232 config ARCH_HAS_FORTIFY_SOURCE
283 bool 233 bool
284 help 234 help
285 An architecture should select this w 235 An architecture should select this when it can successfully
286 build and run with CONFIG_FORTIFY_SO 236 build and run with CONFIG_FORTIFY_SOURCE.
287 237
288 # 238 #
289 # Select if the arch provides a historic keepi 239 # Select if the arch provides a historic keepinit alias for the retain_initrd
290 # command line option 240 # command line option
291 # 241 #
292 config ARCH_HAS_KEEPINITRD 242 config ARCH_HAS_KEEPINITRD
293 bool 243 bool
294 244
295 # Select if arch has all set_memory_ro/rw/x/nx 245 # Select if arch has all set_memory_ro/rw/x/nx() functions in asm/cacheflush.h
296 config ARCH_HAS_SET_MEMORY 246 config ARCH_HAS_SET_MEMORY
297 bool 247 bool
298 248
299 # Select if arch has all set_direct_map_invali 249 # Select if arch has all set_direct_map_invalid/default() functions
300 config ARCH_HAS_SET_DIRECT_MAP 250 config ARCH_HAS_SET_DIRECT_MAP
301 bool 251 bool
302 252
303 # 253 #
304 # Select if the architecture provides the arch 254 # Select if the architecture provides the arch_dma_set_uncached symbol to
305 # either provide an uncached segment alias for !! 255 # either provide an uncached segement alias for a DMA allocation, or
306 # to remap the page tables in place. 256 # to remap the page tables in place.
307 # 257 #
308 config ARCH_HAS_DMA_SET_UNCACHED 258 config ARCH_HAS_DMA_SET_UNCACHED
309 bool 259 bool
310 260
311 # 261 #
312 # Select if the architectures provides the arc 262 # Select if the architectures provides the arch_dma_clear_uncached symbol
313 # to undo an in-place page table remap for unc 263 # to undo an in-place page table remap for uncached access.
314 # 264 #
315 config ARCH_HAS_DMA_CLEAR_UNCACHED 265 config ARCH_HAS_DMA_CLEAR_UNCACHED
316 bool 266 bool
317 267
318 config ARCH_HAS_CPU_FINALIZE_INIT !! 268 # Select if arch init_task must go in the __init_task_data section
>> 269 config ARCH_TASK_STRUCT_ON_STACK
319 bool 270 bool
320 271
321 # The architecture has a per-task state that i !! 272 # Select if arch has its private alloc_task_struct() function
322 config ARCH_HAS_CPU_PASID !! 273 config ARCH_TASK_STRUCT_ALLOCATOR
323 bool 274 bool
324 select IOMMU_MM_DATA <<
325 275
326 config HAVE_ARCH_THREAD_STRUCT_WHITELIST 276 config HAVE_ARCH_THREAD_STRUCT_WHITELIST
327 bool 277 bool
>> 278 depends on !ARCH_TASK_STRUCT_ALLOCATOR
328 help 279 help
329 An architecture should select this t 280 An architecture should select this to provide hardened usercopy
330 knowledge about what region of the t 281 knowledge about what region of the thread_struct should be
331 whitelisted for copying to userspace 282 whitelisted for copying to userspace. Normally this is only the
332 FPU registers. Specifically, arch_th 283 FPU registers. Specifically, arch_thread_struct_whitelist()
333 should be implemented. Without this, 284 should be implemented. Without this, the entire thread_struct
334 field in task_struct will be left wh 285 field in task_struct will be left whitelisted.
335 286
336 # Select if arch wants to size task_struct dyn !! 287 # Select if arch has its private alloc_thread_stack() function
337 config ARCH_WANTS_DYNAMIC_TASK_STRUCT !! 288 config ARCH_THREAD_STACK_ALLOCATOR
338 bool 289 bool
339 290
340 config ARCH_WANTS_NO_INSTR !! 291 # Select if arch wants to size task_struct dynamically via arch_task_struct_size:
>> 292 config ARCH_WANTS_DYNAMIC_TASK_STRUCT
341 bool 293 bool
342 help <<
343 An architecture should select this i <<
344 functions to denote that the toolcha <<
345 functions and is required for correc <<
346 294
347 config ARCH_32BIT_OFF_T 295 config ARCH_32BIT_OFF_T
348 bool 296 bool
349 depends on !64BIT 297 depends on !64BIT
350 help 298 help
351 All new 32-bit architectures should 299 All new 32-bit architectures should have 64-bit off_t type on
352 userspace side which corresponds to 300 userspace side which corresponds to the loff_t kernel type. This
353 is the requirement for modern ABIs. 301 is the requirement for modern ABIs. Some existing architectures
354 still support 32-bit off_t. This opt 302 still support 32-bit off_t. This option is enabled for all such
355 architectures explicitly. 303 architectures explicitly.
356 304
357 # Selected by 64 bit architectures which have <<
358 config ARCH_32BIT_USTAT_F_TINODE <<
359 bool <<
360 <<
361 config HAVE_ASM_MODVERSIONS 305 config HAVE_ASM_MODVERSIONS
362 bool 306 bool
363 help 307 help
364 This symbol should be selected by an !! 308 This symbol should be selected by an architecure if it provides
365 <asm/asm-prototypes.h> to support th 309 <asm/asm-prototypes.h> to support the module versioning for symbols
366 exported from assembly code. 310 exported from assembly code.
367 311
368 config HAVE_REGS_AND_STACK_ACCESS_API 312 config HAVE_REGS_AND_STACK_ACCESS_API
369 bool 313 bool
370 help 314 help
371 This symbol should be selected by an !! 315 This symbol should be selected by an architecure if it supports
372 the API needed to access registers a 316 the API needed to access registers and stack entries from pt_regs,
373 declared in asm/ptrace.h 317 declared in asm/ptrace.h
374 For example the kprobes-based event 318 For example the kprobes-based event tracer needs this API.
375 319
376 config HAVE_RSEQ 320 config HAVE_RSEQ
377 bool 321 bool
378 depends on HAVE_REGS_AND_STACK_ACCESS_ 322 depends on HAVE_REGS_AND_STACK_ACCESS_API
379 help 323 help
380 This symbol should be selected by an 324 This symbol should be selected by an architecture if it
381 supports an implementation of restar 325 supports an implementation of restartable sequences.
382 326
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 327 config HAVE_FUNCTION_ARG_ACCESS_API
390 bool 328 bool
391 help 329 help
392 This symbol should be selected by an !! 330 This symbol should be selected by an architecure if it supports
393 the API needed to access function ar 331 the API needed to access function arguments from pt_regs,
394 declared in asm/ptrace.h 332 declared in asm/ptrace.h
395 333
396 config HAVE_HW_BREAKPOINT 334 config HAVE_HW_BREAKPOINT
397 bool 335 bool
398 depends on PERF_EVENTS 336 depends on PERF_EVENTS
399 337
400 config HAVE_MIXED_BREAKPOINTS_REGS 338 config HAVE_MIXED_BREAKPOINTS_REGS
401 bool 339 bool
402 depends on HAVE_HW_BREAKPOINT 340 depends on HAVE_HW_BREAKPOINT
403 help 341 help
404 Depending on the arch implementation 342 Depending on the arch implementation of hardware breakpoints,
405 some of them have separate registers 343 some of them have separate registers for data and instruction
406 breakpoints addresses, others have m 344 breakpoints addresses, others have mixed registers to store
407 them but define the access type in a 345 them but define the access type in a control register.
408 Select this option if your arch impl 346 Select this option if your arch implements breakpoints under the
409 latter fashion. 347 latter fashion.
410 348
411 config HAVE_USER_RETURN_NOTIFIER 349 config HAVE_USER_RETURN_NOTIFIER
412 bool 350 bool
413 351
414 config HAVE_PERF_EVENTS_NMI 352 config HAVE_PERF_EVENTS_NMI
415 bool 353 bool
416 help 354 help
417 System hardware can generate an NMI 355 System hardware can generate an NMI using the perf event
418 subsystem. Also has support for cal 356 subsystem. Also has support for calculating CPU cycle events
419 to determine how many clock cycles i 357 to determine how many clock cycles in a given period.
420 358
421 config HAVE_HARDLOCKUP_DETECTOR_PERF 359 config HAVE_HARDLOCKUP_DETECTOR_PERF
422 bool 360 bool
423 depends on HAVE_PERF_EVENTS_NMI 361 depends on HAVE_PERF_EVENTS_NMI
424 help 362 help
425 The arch chooses to use the generic 363 The arch chooses to use the generic perf-NMI-based hardlockup
426 detector. Must define HAVE_PERF_EVEN 364 detector. Must define HAVE_PERF_EVENTS_NMI.
427 365
428 config HAVE_HARDLOCKUP_DETECTOR_ARCH !! 366 config HAVE_NMI_WATCHDOG
>> 367 depends on HAVE_NMI
429 bool 368 bool
430 help 369 help
431 The arch provides its own hardlockup !! 370 The arch provides a low level NMI watchdog. It provides
432 of the generic ones. !! 371 asm/nmi.h, and defines its own arch_touch_nmi_watchdog().
433 372
434 It uses the same command line parame !! 373 config HAVE_HARDLOCKUP_DETECTOR_ARCH
435 as the generic hardlockup detectors. !! 374 bool
>> 375 select HAVE_NMI_WATCHDOG
>> 376 help
>> 377 The arch chooses to provide its own hardlockup detector, which is
>> 378 a superset of the HAVE_NMI_WATCHDOG. It also conforms to config
>> 379 interfaces and parameters provided by hardlockup detector subsystem.
436 380
437 config HAVE_PERF_REGS 381 config HAVE_PERF_REGS
438 bool 382 bool
439 help 383 help
440 Support selective register dumps for 384 Support selective register dumps for perf events. This includes
441 bit-mapping of each registers and a 385 bit-mapping of each registers and a unique architecture id.
442 386
443 config HAVE_PERF_USER_STACK_DUMP 387 config HAVE_PERF_USER_STACK_DUMP
444 bool 388 bool
445 help 389 help
446 Support user stack dumps for perf ev 390 Support user stack dumps for perf event samples. This needs
447 access to the user stack pointer whi 391 access to the user stack pointer which is not unified across
448 architectures. 392 architectures.
449 393
450 config HAVE_ARCH_JUMP_LABEL 394 config HAVE_ARCH_JUMP_LABEL
451 bool 395 bool
452 396
453 config HAVE_ARCH_JUMP_LABEL_RELATIVE 397 config HAVE_ARCH_JUMP_LABEL_RELATIVE
454 bool 398 bool
455 399
456 config MMU_GATHER_TABLE_FREE 400 config MMU_GATHER_TABLE_FREE
457 bool 401 bool
458 402
459 config MMU_GATHER_RCU_TABLE_FREE 403 config MMU_GATHER_RCU_TABLE_FREE
460 bool 404 bool
461 select MMU_GATHER_TABLE_FREE 405 select MMU_GATHER_TABLE_FREE
462 406
463 config MMU_GATHER_PAGE_SIZE 407 config MMU_GATHER_PAGE_SIZE
464 bool 408 bool
465 409
466 config MMU_GATHER_NO_RANGE 410 config MMU_GATHER_NO_RANGE
467 bool 411 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 <<
475 412
476 config MMU_GATHER_NO_GATHER 413 config MMU_GATHER_NO_GATHER
477 bool 414 bool
478 depends on MMU_GATHER_TABLE_FREE 415 depends on MMU_GATHER_TABLE_FREE
479 416
480 config ARCH_WANT_IRQS_OFF_ACTIVATE_MM 417 config ARCH_WANT_IRQS_OFF_ACTIVATE_MM
481 bool 418 bool
482 help 419 help
483 Temporary select until all architect 420 Temporary select until all architectures can be converted to have
484 irqs disabled over activate_mm. Arch 421 irqs disabled over activate_mm. Architectures that do IPI based TLB
485 shootdowns should enable this. 422 shootdowns should enable this.
486 423
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 424 config ARCH_HAVE_NMI_SAFE_CMPXCHG
520 bool 425 bool
521 426
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 427 config HAVE_ALIGNED_STRUCT_PAGE
535 bool 428 bool
536 help 429 help
537 This makes sure that struct pages ar 430 This makes sure that struct pages are double word aligned and that
538 e.g. the SLUB allocator can perform 431 e.g. the SLUB allocator can perform double word atomic operations
539 on a struct page for better performa 432 on a struct page for better performance. However selecting this
540 might increase the size of a struct 433 might increase the size of a struct page by a word.
541 434
542 config HAVE_CMPXCHG_LOCAL 435 config HAVE_CMPXCHG_LOCAL
543 bool 436 bool
544 437
545 config HAVE_CMPXCHG_DOUBLE 438 config HAVE_CMPXCHG_DOUBLE
546 bool 439 bool
547 440
548 config ARCH_WEAK_RELEASE_ACQUIRE 441 config ARCH_WEAK_RELEASE_ACQUIRE
549 bool 442 bool
550 443
551 config ARCH_WANT_IPC_PARSE_VERSION 444 config ARCH_WANT_IPC_PARSE_VERSION
552 bool 445 bool
553 446
554 config ARCH_WANT_COMPAT_IPC_PARSE_VERSION 447 config ARCH_WANT_COMPAT_IPC_PARSE_VERSION
555 bool 448 bool
556 449
557 config ARCH_WANT_OLD_COMPAT_IPC 450 config ARCH_WANT_OLD_COMPAT_IPC
558 select ARCH_WANT_COMPAT_IPC_PARSE_VERS 451 select ARCH_WANT_COMPAT_IPC_PARSE_VERSION
559 bool 452 bool
560 453
561 config HAVE_ARCH_SECCOMP <<
562 bool <<
563 help <<
564 An arch should select this symbol to <<
565 syscall policy), and must provide an <<
566 and compat syscalls if the asm-gener <<
567 - __NR_seccomp_read_32 <<
568 - __NR_seccomp_write_32 <<
569 - __NR_seccomp_exit_32 <<
570 - __NR_seccomp_sigreturn_32 <<
571 <<
572 config HAVE_ARCH_SECCOMP_FILTER 454 config HAVE_ARCH_SECCOMP_FILTER
573 bool 455 bool
574 select HAVE_ARCH_SECCOMP <<
575 help 456 help
576 An arch should select this symbol if 457 An arch should select this symbol if it provides all of these things:
577 - all the requirements for HAVE_ARCH <<
578 - syscall_get_arch() 458 - syscall_get_arch()
579 - syscall_get_arguments() 459 - syscall_get_arguments()
580 - syscall_rollback() 460 - syscall_rollback()
581 - syscall_set_return_value() 461 - syscall_set_return_value()
582 - SIGSYS siginfo_t support 462 - SIGSYS siginfo_t support
583 - secure_computing is called from a 463 - secure_computing is called from a ptrace_event()-safe context
584 - secure_computing return value is c 464 - secure_computing return value is checked and a return value of -1
585 results in the system call being s 465 results in the system call being skipped immediately.
586 - seccomp syscall wired up 466 - seccomp syscall wired up
587 - if !HAVE_SPARSE_SYSCALL_NR, have S <<
588 SECCOMP_ARCH_NATIVE_NR, SECCOMP_AR <<
589 COMPAT is supported, have the SECC <<
590 <<
591 config SECCOMP <<
592 prompt "Enable seccomp to safely execu <<
593 def_bool y <<
594 depends on HAVE_ARCH_SECCOMP <<
595 help <<
596 This kernel feature is useful for nu <<
597 that may need to handle untrusted by <<
598 execution. By using pipes or other t <<
599 to the process as file descriptors s <<
600 syscalls, it's possible to isolate t <<
601 own address space using seccomp. Onc <<
602 prctl(PR_SET_SECCOMP) or the seccomp <<
603 disabled and the task is only allowe <<
604 syscalls defined by each seccomp mod <<
605 <<
606 If unsure, say Y. <<
607 467
608 config SECCOMP_FILTER 468 config SECCOMP_FILTER
609 def_bool y 469 def_bool y
610 depends on HAVE_ARCH_SECCOMP_FILTER && 470 depends on HAVE_ARCH_SECCOMP_FILTER && SECCOMP && NET
611 help 471 help
612 Enable tasks to build secure computi 472 Enable tasks to build secure computing environments defined
613 in terms of Berkeley Packet Filter p 473 in terms of Berkeley Packet Filter programs which implement
614 task-defined system call filtering p 474 task-defined system call filtering polices.
615 475
616 See Documentation/userspace-api/secc 476 See Documentation/userspace-api/seccomp_filter.rst for details.
617 477
618 config SECCOMP_CACHE_DEBUG <<
619 bool "Show seccomp filter cache status <<
620 depends on SECCOMP_FILTER && !HAVE_SPA <<
621 depends on PROC_FS <<
622 help <<
623 This enables the /proc/pid/seccomp_c <<
624 seccomp cache data. The file format <<
625 the file requires CAP_SYS_ADMIN. <<
626 <<
627 This option is for debugging only. E <<
628 an adversary may be able to infer th <<
629 <<
630 If unsure, say N. <<
631 <<
632 config HAVE_ARCH_STACKLEAK 478 config HAVE_ARCH_STACKLEAK
633 bool 479 bool
634 help 480 help
635 An architecture should select this i 481 An architecture should select this if it has the code which
636 fills the used part of the kernel st 482 fills the used part of the kernel stack with the STACKLEAK_POISON
637 value before returning from system c 483 value before returning from system calls.
638 484
639 config HAVE_STACKPROTECTOR 485 config HAVE_STACKPROTECTOR
640 bool 486 bool
641 help 487 help
642 An arch should select this symbol if 488 An arch should select this symbol if:
643 - it has implemented a stack canary 489 - it has implemented a stack canary (e.g. __stack_chk_guard)
644 490
645 config STACKPROTECTOR 491 config STACKPROTECTOR
646 bool "Stack Protector buffer overflow 492 bool "Stack Protector buffer overflow detection"
647 depends on HAVE_STACKPROTECTOR 493 depends on HAVE_STACKPROTECTOR
648 depends on $(cc-option,-fstack-protect 494 depends on $(cc-option,-fstack-protector)
649 default y 495 default y
650 help 496 help
651 This option turns on the "stack-prot 497 This option turns on the "stack-protector" GCC feature. This
652 feature puts, at the beginning of fu 498 feature puts, at the beginning of functions, a canary value on
653 the stack just before the return add 499 the stack just before the return address, and validates
654 the value just before actually retur 500 the value just before actually returning. Stack based buffer
655 overflows (that need to overwrite th 501 overflows (that need to overwrite this return address) now also
656 overwrite the canary, which gets det 502 overwrite the canary, which gets detected and the attack is then
657 neutralized via a kernel panic. 503 neutralized via a kernel panic.
658 504
659 Functions will have the stack-protec 505 Functions will have the stack-protector canary logic added if they
660 have an 8-byte or larger character a 506 have an 8-byte or larger character array on the stack.
661 507
662 This feature requires gcc version 4. 508 This feature requires gcc version 4.2 or above, or a distribution
663 gcc with the feature backported ("-f 509 gcc with the feature backported ("-fstack-protector").
664 510
665 On an x86 "defconfig" build, this fe 511 On an x86 "defconfig" build, this feature adds canary checks to
666 about 3% of all kernel functions, wh 512 about 3% of all kernel functions, which increases kernel code size
667 by about 0.3%. 513 by about 0.3%.
668 514
669 config STACKPROTECTOR_STRONG 515 config STACKPROTECTOR_STRONG
670 bool "Strong Stack Protector" 516 bool "Strong Stack Protector"
671 depends on STACKPROTECTOR 517 depends on STACKPROTECTOR
672 depends on $(cc-option,-fstack-protect 518 depends on $(cc-option,-fstack-protector-strong)
673 default y 519 default y
674 help 520 help
675 Functions will have the stack-protec 521 Functions will have the stack-protector canary logic added in any
676 of the following conditions: 522 of the following conditions:
677 523
678 - local variable's address used as p 524 - local variable's address used as part of the right hand side of an
679 assignment or function argument 525 assignment or function argument
680 - local variable is an array (or uni 526 - local variable is an array (or union containing an array),
681 regardless of array type or length 527 regardless of array type or length
682 - uses register local variables 528 - uses register local variables
683 529
684 This feature requires gcc version 4. 530 This feature requires gcc version 4.9 or above, or a distribution
685 gcc with the feature backported ("-f 531 gcc with the feature backported ("-fstack-protector-strong").
686 532
687 On an x86 "defconfig" build, this fe 533 On an x86 "defconfig" build, this feature adds canary checks to
688 about 20% of all kernel functions, w 534 about 20% of all kernel functions, which increases the kernel code
689 size by about 2%. 535 size by about 2%.
690 536
691 config ARCH_SUPPORTS_SHADOW_CALL_STACK 537 config ARCH_SUPPORTS_SHADOW_CALL_STACK
692 bool 538 bool
693 help 539 help
694 An architecture should select this i !! 540 An architecture should select this if it supports Clang's Shadow
695 Shadow Call Stack and implements run !! 541 Call Stack and implements runtime support for shadow stack
696 switching. 542 switching.
697 543
698 config SHADOW_CALL_STACK 544 config SHADOW_CALL_STACK
699 bool "Shadow Call Stack" !! 545 bool "Clang Shadow Call Stack"
700 depends on ARCH_SUPPORTS_SHADOW_CALL_S !! 546 depends on CC_IS_CLANG && ARCH_SUPPORTS_SHADOW_CALL_STACK
701 depends on DYNAMIC_FTRACE_WITH_ARGS || !! 547 depends on DYNAMIC_FTRACE_WITH_REGS || !FUNCTION_GRAPH_TRACER
702 depends on MMU !! 548 help
703 help !! 549 This option enables Clang's Shadow Call Stack, which uses a
704 This option enables the compiler's S !! 550 shadow stack to protect function return addresses from being
705 uses a shadow stack to protect funct !! 551 overwritten by an attacker. More information can be found in
706 being overwritten by an attacker. Mo !! 552 Clang's documentation:
707 in the compiler's documentation: <<
708 553
709 - Clang: https://clang.llvm.org/docs !! 554 https://clang.llvm.org/docs/ShadowCallStack.html
710 - GCC: https://gcc.gnu.org/onlinedoc <<
711 555
712 Note that security guarantees in the 556 Note that security guarantees in the kernel differ from the
713 ones documented for user space. The 557 ones documented for user space. The kernel must store addresses
714 of shadow stacks in memory, which me 558 of shadow stacks in memory, which means an attacker capable of
715 reading and writing arbitrary memory 559 reading and writing arbitrary memory may be able to locate them
716 and hijack control flow by modifying 560 and hijack control flow by modifying the stacks.
717 561
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 <<
726 bool <<
727 help <<
728 Selected if the kernel will be built <<
729 <<
730 config LTO_CLANG <<
731 bool <<
732 select LTO <<
733 help <<
734 Selected if the kernel will be built <<
735 <<
736 config ARCH_SUPPORTS_LTO_CLANG <<
737 bool <<
738 help <<
739 An architecture should select this o <<
740 - compiling with Clang, <<
741 - compiling inline assembly with Cla <<
742 - and linking with LLD. <<
743 <<
744 config ARCH_SUPPORTS_LTO_CLANG_THIN <<
745 bool <<
746 help <<
747 An architecture should select this o <<
748 ThinLTO mode. <<
749 <<
750 config HAS_LTO_CLANG <<
751 def_bool y <<
752 depends on CC_IS_CLANG && LD_IS_LLD && <<
753 depends on $(success,$(NM) --help | he <<
754 depends on $(success,$(AR) --help | he <<
755 depends on ARCH_SUPPORTS_LTO_CLANG <<
756 depends on !FTRACE_MCOUNT_USE_RECORDMC <<
757 # https://github.com/ClangBuiltLinux/l <<
758 depends on (!KASAN || KASAN_HW_TAGS || <<
759 depends on (!KCOV || CLANG_VERSION >= <<
760 depends on !GCOV_KERNEL <<
761 help <<
762 The compiler and Kconfig options sup <<
763 LTO. <<
764 <<
765 choice <<
766 prompt "Link Time Optimization (LTO)" <<
767 default LTO_NONE <<
768 help <<
769 This option enables Link Time Optimi <<
770 compiler to optimize binaries global <<
771 <<
772 If unsure, select LTO_NONE. Note tha <<
773 so it's disabled by default. <<
774 <<
775 config LTO_NONE <<
776 bool "None" <<
777 help <<
778 Build the kernel normally, without L <<
779 <<
780 config LTO_CLANG_FULL <<
781 bool "Clang Full LTO (EXPERIMENTAL)" <<
782 depends on HAS_LTO_CLANG <<
783 depends on !COMPILE_TEST <<
784 select LTO_CLANG <<
785 help <<
786 This option enables Clang's full Lin <<
787 allows the compiler to optimize the <<
788 this option, the compiler generates <<
789 object files, and the actual compila <<
790 the LTO link step, which may take se <<
791 kernel configuration. More informati <<
792 documentation: <<
793 <<
794 https://llvm.org/docs/LinkTimeOpti <<
795 <<
796 During link time, this option can us <<
797 may take much longer than the ThinLT <<
798 <<
799 config LTO_CLANG_THIN <<
800 bool "Clang ThinLTO (EXPERIMENTAL)" <<
801 depends on HAS_LTO_CLANG && ARCH_SUPPO <<
802 select LTO_CLANG <<
803 help <<
804 This option enables Clang's ThinLTO, <<
805 optimization and faster incremental <<
806 CONFIG_LTO_CLANG_FULL option. More i <<
807 from Clang's documentation: <<
808 <<
809 https://clang.llvm.org/docs/ThinLT <<
810 <<
811 If unsure, say Y. <<
812 endchoice <<
813 <<
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 562 config HAVE_ARCH_WITHIN_STACK_FRAMES
879 bool 563 bool
880 help 564 help
881 An architecture should select this i 565 An architecture should select this if it can walk the kernel stack
882 frames to determine if an object is 566 frames to determine if an object is part of either the arguments
883 or local variables (i.e. that it exc 567 or local variables (i.e. that it excludes saved return addresses,
884 and similar) by implementing an inli 568 and similar) by implementing an inline arch_within_stack_frames(),
885 which is used by CONFIG_HARDENED_USE 569 which is used by CONFIG_HARDENED_USERCOPY.
886 570
887 config HAVE_CONTEXT_TRACKING_USER !! 571 config HAVE_CONTEXT_TRACKING
888 bool 572 bool
889 help 573 help
890 Provide kernel/user boundaries probe 574 Provide kernel/user boundaries probes necessary for subsystems
891 that need it, such as userspace RCU 575 that need it, such as userspace RCU extended quiescent state.
892 Syscalls need to be wrapped inside u 576 Syscalls need to be wrapped inside user_exit()-user_enter(), either
893 optimized behind static key or throu 577 optimized behind static key or through the slow path using TIF_NOHZ
894 flag. Exceptions handlers must be wr 578 flag. Exceptions handlers must be wrapped as well. Irqs are already
895 protected inside ct_irq_enter/ct_irq !! 579 protected inside rcu_irq_enter/rcu_irq_exit() but preemption or signal
896 handling on irq exit still need to b 580 handling on irq exit still need to be protected.
897 581
898 config HAVE_CONTEXT_TRACKING_USER_OFFSTACK <<
899 bool <<
900 help <<
901 Architecture neither relies on excep <<
902 nor on schedule_user(). Also preempt <<
903 preempt_schedule_irq() can't be call <<
904 while context tracking is CT_STATE_U <<
905 entry implementation where the follo <<
906 critical entry code, ie: before user <<
907 <<
908 - Critical entry code isn't preempti <<
909 not interruptible). <<
910 - No use of RCU read side critical s <<
911 got called. <<
912 - No use of instrumentation, unless <<
913 called. <<
914 <<
915 config HAVE_TIF_NOHZ 582 config HAVE_TIF_NOHZ
916 bool 583 bool
917 help 584 help
918 Arch relies on TIF_NOHZ and syscall 585 Arch relies on TIF_NOHZ and syscall slow path to implement context
919 tracking calls to user_enter()/user_ 586 tracking calls to user_enter()/user_exit().
920 587
921 config HAVE_VIRT_CPU_ACCOUNTING 588 config HAVE_VIRT_CPU_ACCOUNTING
922 bool 589 bool
923 590
924 config HAVE_VIRT_CPU_ACCOUNTING_IDLE <<
925 bool <<
926 help <<
927 Architecture has its own way to acco <<
928 doesn't implement vtime_account_idle <<
929 <<
930 config ARCH_HAS_SCALED_CPUTIME 591 config ARCH_HAS_SCALED_CPUTIME
931 bool 592 bool
932 593
933 config HAVE_VIRT_CPU_ACCOUNTING_GEN 594 config HAVE_VIRT_CPU_ACCOUNTING_GEN
934 bool 595 bool
935 default y if 64BIT 596 default y if 64BIT
936 help 597 help
937 With VIRT_CPU_ACCOUNTING_GEN, cputim 598 With VIRT_CPU_ACCOUNTING_GEN, cputime_t becomes 64-bit.
938 Before enabling this option, arch co 599 Before enabling this option, arch code must be audited
939 to ensure there are no races in conc 600 to ensure there are no races in concurrent read/write of
940 cputime_t. For example, reading/writ 601 cputime_t. For example, reading/writing 64-bit cputime_t on
941 some 32-bit arches may require multi 602 some 32-bit arches may require multiple accesses, so proper
942 locking is needed to protect against 603 locking is needed to protect against concurrent accesses.
943 604
>> 605
944 config HAVE_IRQ_TIME_ACCOUNTING 606 config HAVE_IRQ_TIME_ACCOUNTING
945 bool 607 bool
946 help 608 help
947 Archs need to ensure they use a high 609 Archs need to ensure they use a high enough resolution clock to
948 support irq time accounting and then 610 support irq time accounting and then call enable_sched_clock_irqtime().
949 611
950 config HAVE_MOVE_PUD <<
951 bool <<
952 help <<
953 Architectures that select this are a <<
954 PUD level. If there are only 3 page <<
955 happens at the PGD level. <<
956 <<
957 config HAVE_MOVE_PMD 612 config HAVE_MOVE_PMD
958 bool 613 bool
959 help 614 help
960 Archs that select this are able to m 615 Archs that select this are able to move page tables at the PMD level.
961 616
962 config HAVE_ARCH_TRANSPARENT_HUGEPAGE 617 config HAVE_ARCH_TRANSPARENT_HUGEPAGE
963 bool 618 bool
964 619
965 config HAVE_ARCH_TRANSPARENT_HUGEPAGE_PUD 620 config HAVE_ARCH_TRANSPARENT_HUGEPAGE_PUD
966 bool 621 bool
967 622
968 config HAVE_ARCH_HUGE_VMAP 623 config HAVE_ARCH_HUGE_VMAP
969 bool 624 bool
970 625
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 626 config ARCH_WANT_HUGE_PMD_SHARE
981 bool 627 bool
982 628
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 629 config HAVE_ARCH_SOFT_DIRTY
992 bool 630 bool
993 631
994 config HAVE_MOD_ARCH_SPECIFIC 632 config HAVE_MOD_ARCH_SPECIFIC
995 bool 633 bool
996 help 634 help
997 The arch uses struct mod_arch_specif 635 The arch uses struct mod_arch_specific to store data. Many arches
998 just need a simple module loader wit 636 just need a simple module loader without arch specific data - those
999 should not enable this. 637 should not enable this.
1000 638
1001 config MODULES_USE_ELF_RELA 639 config MODULES_USE_ELF_RELA
1002 bool 640 bool
1003 help 641 help
1004 Modules only use ELF RELA relocatio 642 Modules only use ELF RELA relocations. Modules with ELF REL
1005 relocations will give an error. 643 relocations will give an error.
1006 644
1007 config MODULES_USE_ELF_REL 645 config MODULES_USE_ELF_REL
1008 bool 646 bool
1009 help 647 help
1010 Modules only use ELF REL relocation 648 Modules only use ELF REL relocations. Modules with ELF RELA
1011 relocations will give an error. 649 relocations will give an error.
1012 650
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 651 config HAVE_IRQ_EXIT_ON_IRQ_STACK
1028 bool 652 bool
1029 help 653 help
1030 Architecture doesn't only execute t 654 Architecture doesn't only execute the irq handler on the irq stack
1031 but also irq_exit(). This way we ca 655 but also irq_exit(). This way we can process softirqs on this irq
1032 stack instead of switching to a new 656 stack instead of switching to a new one when we call __do_softirq()
1033 in the end of an hardirq. 657 in the end of an hardirq.
1034 This spares a stack switch and impr 658 This spares a stack switch and improves cache usage on softirq
1035 processing. 659 processing.
1036 660
1037 config HAVE_SOFTIRQ_ON_OWN_STACK <<
1038 bool <<
1039 help <<
1040 Architecture provides a function to <<
1041 separate 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 <<
1053 config PGTABLE_LEVELS 661 config PGTABLE_LEVELS
1054 int 662 int
1055 default 2 663 default 2
1056 664
1057 config ARCH_HAS_ELF_RANDOMIZE 665 config ARCH_HAS_ELF_RANDOMIZE
1058 bool 666 bool
1059 help 667 help
1060 An architecture supports choosing r 668 An architecture supports choosing randomized locations for
1061 stack, mmap, brk, and ET_DYN. Defin 669 stack, mmap, brk, and ET_DYN. Defined functions:
1062 - arch_mmap_rnd() 670 - arch_mmap_rnd()
1063 - arch_randomize_brk() 671 - arch_randomize_brk()
1064 672
1065 config HAVE_ARCH_MMAP_RND_BITS 673 config HAVE_ARCH_MMAP_RND_BITS
1066 bool 674 bool
1067 help 675 help
1068 An arch should select this symbol i 676 An arch should select this symbol if it supports setting a variable
1069 number of bits for use in establish 677 number of bits for use in establishing the base address for mmap
1070 allocations, has MMU enabled and pr 678 allocations, has MMU enabled and provides values for both:
1071 - ARCH_MMAP_RND_BITS_MIN 679 - ARCH_MMAP_RND_BITS_MIN
1072 - ARCH_MMAP_RND_BITS_MAX 680 - ARCH_MMAP_RND_BITS_MAX
1073 681
1074 config HAVE_EXIT_THREAD 682 config HAVE_EXIT_THREAD
1075 bool 683 bool
1076 help 684 help
1077 An architecture implements exit_thr 685 An architecture implements exit_thread.
1078 686
1079 config ARCH_MMAP_RND_BITS_MIN 687 config ARCH_MMAP_RND_BITS_MIN
1080 int 688 int
1081 689
1082 config ARCH_MMAP_RND_BITS_MAX 690 config ARCH_MMAP_RND_BITS_MAX
1083 int 691 int
1084 692
1085 config ARCH_MMAP_RND_BITS_DEFAULT 693 config ARCH_MMAP_RND_BITS_DEFAULT
1086 int 694 int
1087 695
1088 config ARCH_MMAP_RND_BITS 696 config ARCH_MMAP_RND_BITS
1089 int "Number of bits to use for ASLR o 697 int "Number of bits to use for ASLR of mmap base address" if EXPERT
1090 range ARCH_MMAP_RND_BITS_MIN ARCH_MMA 698 range ARCH_MMAP_RND_BITS_MIN ARCH_MMAP_RND_BITS_MAX
1091 default ARCH_MMAP_RND_BITS_DEFAULT if 699 default ARCH_MMAP_RND_BITS_DEFAULT if ARCH_MMAP_RND_BITS_DEFAULT
1092 default ARCH_MMAP_RND_BITS_MIN 700 default ARCH_MMAP_RND_BITS_MIN
1093 depends on HAVE_ARCH_MMAP_RND_BITS 701 depends on HAVE_ARCH_MMAP_RND_BITS
1094 help 702 help
1095 This value can be used to select th 703 This value can be used to select the number of bits to use to
1096 determine the random offset to the 704 determine the random offset to the base address of vma regions
1097 resulting from mmap allocations. Th 705 resulting from mmap allocations. This value will be bounded
1098 by the architecture's minimum and m 706 by the architecture's minimum and maximum supported values.
1099 707
1100 This value can be changed after boo 708 This value can be changed after boot using the
1101 /proc/sys/vm/mmap_rnd_bits tunable 709 /proc/sys/vm/mmap_rnd_bits tunable
1102 710
1103 config HAVE_ARCH_MMAP_RND_COMPAT_BITS 711 config HAVE_ARCH_MMAP_RND_COMPAT_BITS
1104 bool 712 bool
1105 help 713 help
1106 An arch should select this symbol i 714 An arch should select this symbol if it supports running applications
1107 in compatibility mode, supports set 715 in compatibility mode, supports setting a variable number of bits for
1108 use in establishing the base addres 716 use in establishing the base address for mmap allocations, has MMU
1109 enabled and provides values for bot 717 enabled and provides values for both:
1110 - ARCH_MMAP_RND_COMPAT_BITS_MIN 718 - ARCH_MMAP_RND_COMPAT_BITS_MIN
1111 - ARCH_MMAP_RND_COMPAT_BITS_MAX 719 - ARCH_MMAP_RND_COMPAT_BITS_MAX
1112 720
1113 config ARCH_MMAP_RND_COMPAT_BITS_MIN 721 config ARCH_MMAP_RND_COMPAT_BITS_MIN
1114 int 722 int
1115 723
1116 config ARCH_MMAP_RND_COMPAT_BITS_MAX 724 config ARCH_MMAP_RND_COMPAT_BITS_MAX
1117 int 725 int
1118 726
1119 config ARCH_MMAP_RND_COMPAT_BITS_DEFAULT 727 config ARCH_MMAP_RND_COMPAT_BITS_DEFAULT
1120 int 728 int
1121 729
1122 config ARCH_MMAP_RND_COMPAT_BITS 730 config ARCH_MMAP_RND_COMPAT_BITS
1123 int "Number of bits to use for ASLR o 731 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 732 range ARCH_MMAP_RND_COMPAT_BITS_MIN ARCH_MMAP_RND_COMPAT_BITS_MAX
1125 default ARCH_MMAP_RND_COMPAT_BITS_DEF 733 default ARCH_MMAP_RND_COMPAT_BITS_DEFAULT if ARCH_MMAP_RND_COMPAT_BITS_DEFAULT
1126 default ARCH_MMAP_RND_COMPAT_BITS_MIN 734 default ARCH_MMAP_RND_COMPAT_BITS_MIN
1127 depends on HAVE_ARCH_MMAP_RND_COMPAT_ 735 depends on HAVE_ARCH_MMAP_RND_COMPAT_BITS
1128 help 736 help
1129 This value can be used to select th 737 This value can be used to select the number of bits to use to
1130 determine the random offset to the 738 determine the random offset to the base address of vma regions
1131 resulting from mmap allocations for 739 resulting from mmap allocations for compatible applications This
1132 value will be bounded by the archit 740 value will be bounded by the architecture's minimum and maximum
1133 supported values. 741 supported values.
1134 742
1135 This value can be changed after boo 743 This value can be changed after boot using the
1136 /proc/sys/vm/mmap_rnd_compat_bits t 744 /proc/sys/vm/mmap_rnd_compat_bits tunable
1137 745
1138 config HAVE_ARCH_COMPAT_MMAP_BASES 746 config HAVE_ARCH_COMPAT_MMAP_BASES
1139 bool 747 bool
1140 help 748 help
1141 This allows 64bit applications to i 749 This allows 64bit applications to invoke 32-bit mmap() syscall
1142 and vice-versa 32-bit applications 750 and vice-versa 32-bit applications to call 64-bit mmap().
1143 Required for applications doing dif 751 Required for applications doing different bitness syscalls.
1144 752
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 753 # This allows to use a set of generic functions to determine mmap base
1247 # address by giving priority to top-down sche 754 # address by giving priority to top-down scheme only if the process
1248 # is not in legacy mode (compat task, unlimit 755 # is not in legacy mode (compat task, unlimited stack size or
1249 # sysctl_legacy_va_layout). 756 # sysctl_legacy_va_layout).
1250 # Architecture that selects this option can p 757 # Architecture that selects this option can provide its own version of:
1251 # - STACK_RND_MASK 758 # - STACK_RND_MASK
1252 config ARCH_WANT_DEFAULT_TOPDOWN_MMAP_LAYOUT 759 config ARCH_WANT_DEFAULT_TOPDOWN_MMAP_LAYOUT
1253 bool 760 bool
1254 depends on MMU 761 depends on MMU
1255 select ARCH_HAS_ELF_RANDOMIZE 762 select ARCH_HAS_ELF_RANDOMIZE
1256 763
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 764 config HAVE_STACK_VALIDATION
1274 bool 765 bool
1275 help 766 help
1276 Architecture supports objtool compi !! 767 Architecture supports the 'objtool check' host tool command, which
1277 validation. !! 768 performs compile-time stack metadata validation.
1278 769
1279 config HAVE_RELIABLE_STACKTRACE 770 config HAVE_RELIABLE_STACKTRACE
1280 bool 771 bool
1281 help 772 help
1282 Architecture has either save_stack_ 773 Architecture has either save_stack_trace_tsk_reliable() or
1283 arch_stack_walk_reliable() function 774 arch_stack_walk_reliable() function which only returns a stack trace
1284 if it can guarantee the trace is re 775 if it can guarantee the trace is reliable.
1285 776
1286 config HAVE_ARCH_HASH 777 config HAVE_ARCH_HASH
1287 bool 778 bool
1288 default n 779 default n
1289 help 780 help
1290 If this is set, the architecture pr 781 If this is set, the architecture provides an <asm/hash.h>
1291 file which provides platform-specif 782 file which provides platform-specific implementations of some
1292 functions in <linux/hash.h> or fs/n 783 functions in <linux/hash.h> or fs/namei.c.
1293 784
1294 config HAVE_ARCH_NVRAM_OPS 785 config HAVE_ARCH_NVRAM_OPS
1295 bool 786 bool
1296 787
1297 config ISA_BUS_API 788 config ISA_BUS_API
1298 def_bool ISA 789 def_bool ISA
1299 790
1300 # 791 #
1301 # ABI hall of shame 792 # ABI hall of shame
1302 # 793 #
1303 config CLONE_BACKWARDS 794 config CLONE_BACKWARDS
1304 bool 795 bool
1305 help 796 help
1306 Architecture has tls passed as the 797 Architecture has tls passed as the 4th argument of clone(2),
1307 not the 5th one. 798 not the 5th one.
1308 799
1309 config CLONE_BACKWARDS2 800 config CLONE_BACKWARDS2
1310 bool 801 bool
1311 help 802 help
1312 Architecture has the first two argu 803 Architecture has the first two arguments of clone(2) swapped.
1313 804
1314 config CLONE_BACKWARDS3 805 config CLONE_BACKWARDS3
1315 bool 806 bool
1316 help 807 help
1317 Architecture has tls passed as the 808 Architecture has tls passed as the 3rd argument of clone(2),
1318 not the 5th one. 809 not the 5th one.
1319 810
1320 config ODD_RT_SIGACTION 811 config ODD_RT_SIGACTION
1321 bool 812 bool
1322 help 813 help
1323 Architecture has unusual rt_sigacti 814 Architecture has unusual rt_sigaction(2) arguments
1324 815
1325 config OLD_SIGSUSPEND 816 config OLD_SIGSUSPEND
1326 bool 817 bool
1327 help 818 help
1328 Architecture has old sigsuspend(2) 819 Architecture has old sigsuspend(2) syscall, of one-argument variety
1329 820
1330 config OLD_SIGSUSPEND3 821 config OLD_SIGSUSPEND3
1331 bool 822 bool
1332 help 823 help
1333 Even weirder antique ABI - three-ar 824 Even weirder antique ABI - three-argument sigsuspend(2)
1334 825
1335 config OLD_SIGACTION 826 config OLD_SIGACTION
1336 bool 827 bool
1337 help 828 help
1338 Architecture has old sigaction(2) s 829 Architecture has old sigaction(2) syscall. Nope, not the same
1339 as OLD_SIGSUSPEND | OLD_SIGSUSPEND3 830 as OLD_SIGSUSPEND | OLD_SIGSUSPEND3 - alpha has sigsuspend(2),
1340 but fairly different variant of sig 831 but fairly different variant of sigaction(2), thanks to OSF/1
1341 compatibility... 832 compatibility...
1342 833
1343 config COMPAT_OLD_SIGACTION 834 config COMPAT_OLD_SIGACTION
1344 bool 835 bool
1345 836
1346 config COMPAT_32BIT_TIME 837 config COMPAT_32BIT_TIME
1347 bool "Provide system calls for 32-bit 838 bool "Provide system calls for 32-bit time_t"
1348 default !64BIT || COMPAT 839 default !64BIT || COMPAT
1349 help 840 help
1350 This enables 32 bit time_t support 841 This enables 32 bit time_t support in addition to 64 bit time_t support.
1351 This is relevant on all 32-bit arch 842 This is relevant on all 32-bit architectures, and 64-bit architectures
1352 as part of compat syscall handling. 843 as part of compat syscall handling.
1353 844
1354 config ARCH_NO_PREEMPT 845 config ARCH_NO_PREEMPT
1355 bool 846 bool
1356 847
1357 config ARCH_SUPPORTS_RT 848 config ARCH_SUPPORTS_RT
1358 bool 849 bool
1359 850
1360 config CPU_NO_EFFICIENT_FFS 851 config CPU_NO_EFFICIENT_FFS
1361 def_bool n 852 def_bool n
1362 853
1363 config HAVE_ARCH_VMAP_STACK 854 config HAVE_ARCH_VMAP_STACK
1364 def_bool n 855 def_bool n
1365 help 856 help
1366 An arch should select this symbol i 857 An arch should select this symbol if it can support kernel stacks
1367 in vmalloc space. This means: 858 in vmalloc space. This means:
1368 859
1369 - vmalloc space must be large enoug 860 - vmalloc space must be large enough to hold many kernel stacks.
1370 This may rule out many 32-bit arc 861 This may rule out many 32-bit architectures.
1371 862
1372 - Stacks in vmalloc space need to w 863 - Stacks in vmalloc space need to work reliably. For example, if
1373 vmap page tables are created on d 864 vmap page tables are created on demand, either this mechanism
1374 needs to work while the stack poi 865 needs to work while the stack points to a virtual address with
1375 unpopulated page tables or arch c 866 unpopulated page tables or arch code (switch_to() and switch_mm(),
1376 most likely) needs to ensure that 867 most likely) needs to ensure that the stack's page table entries
1377 are populated before running on a 868 are populated before running on a possibly unpopulated stack.
1378 869
1379 - If the stack overflows into a gua 870 - If the stack overflows into a guard page, something reasonable
1380 should happen. The definition of 871 should happen. The definition of "reasonable" is flexible, but
1381 instantly rebooting without loggi 872 instantly rebooting without logging anything would be unfriendly.
1382 873
1383 config VMAP_STACK 874 config VMAP_STACK
1384 default y 875 default y
1385 bool "Use a virtually-mapped stack" 876 bool "Use a virtually-mapped stack"
1386 depends on HAVE_ARCH_VMAP_STACK 877 depends on HAVE_ARCH_VMAP_STACK
1387 depends on !KASAN || KASAN_HW_TAGS || !! 878 depends on !KASAN || KASAN_VMALLOC
1388 help 879 help
1389 Enable this if you want the use vir 880 Enable this if you want the use virtually-mapped kernel stacks
1390 with guard pages. This causes kern 881 with guard pages. This causes kernel stack overflows to be
1391 caught immediately rather than caus 882 caught immediately rather than causing difficult-to-diagnose
1392 corruption. 883 corruption.
1393 884
1394 To use this with software KASAN mod !! 885 To use this with KASAN, the architecture must support backing
1395 backing virtual mappings with real !! 886 virtual mappings with real shadow memory, and KASAN_VMALLOC must
1396 must be enabled. !! 887 be enabled.
1397 <<
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 888
1435 config ARCH_OPTIONAL_KERNEL_RWX 889 config ARCH_OPTIONAL_KERNEL_RWX
1436 def_bool n 890 def_bool n
1437 891
1438 config ARCH_OPTIONAL_KERNEL_RWX_DEFAULT 892 config ARCH_OPTIONAL_KERNEL_RWX_DEFAULT
1439 def_bool n 893 def_bool n
1440 894
1441 config ARCH_HAS_STRICT_KERNEL_RWX 895 config ARCH_HAS_STRICT_KERNEL_RWX
1442 def_bool n 896 def_bool n
1443 897
1444 config STRICT_KERNEL_RWX 898 config STRICT_KERNEL_RWX
1445 bool "Make kernel text and rodata rea 899 bool "Make kernel text and rodata read-only" if ARCH_OPTIONAL_KERNEL_RWX
1446 depends on ARCH_HAS_STRICT_KERNEL_RWX 900 depends on ARCH_HAS_STRICT_KERNEL_RWX
1447 default !ARCH_OPTIONAL_KERNEL_RWX || 901 default !ARCH_OPTIONAL_KERNEL_RWX || ARCH_OPTIONAL_KERNEL_RWX_DEFAULT
1448 help 902 help
1449 If this is set, kernel text and rod 903 If this is set, kernel text and rodata memory will be made read-only,
1450 and non-text memory will be made no 904 and non-text memory will be made non-executable. This provides
1451 protection against certain security 905 protection against certain security exploits (e.g. executing the heap
1452 or modifying text) 906 or modifying text)
1453 907
1454 These features are considered stand 908 These features are considered standard security practice these days.
1455 You should say Y here in almost all 909 You should say Y here in almost all cases.
1456 910
1457 config ARCH_HAS_STRICT_MODULE_RWX 911 config ARCH_HAS_STRICT_MODULE_RWX
1458 def_bool n 912 def_bool n
1459 913
1460 config STRICT_MODULE_RWX 914 config STRICT_MODULE_RWX
1461 bool "Set loadable kernel module data 915 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 916 depends on ARCH_HAS_STRICT_MODULE_RWX && MODULES
1463 default !ARCH_OPTIONAL_KERNEL_RWX || 917 default !ARCH_OPTIONAL_KERNEL_RWX || ARCH_OPTIONAL_KERNEL_RWX_DEFAULT
1464 help 918 help
1465 If this is set, module text and rod 919 If this is set, module text and rodata memory will be made read-only,
1466 and non-text memory will be made no 920 and non-text memory will be made non-executable. This provides
1467 protection against certain security 921 protection against certain security exploits (e.g. writing to text)
1468 922
1469 # select if the architecture provides an asm/ 923 # select if the architecture provides an asm/dma-direct.h header
1470 config ARCH_HAS_PHYS_TO_DMA 924 config ARCH_HAS_PHYS_TO_DMA
1471 bool 925 bool
1472 926
1473 config HAVE_ARCH_COMPILER_H 927 config HAVE_ARCH_COMPILER_H
1474 bool 928 bool
1475 help 929 help
1476 An architecture can select this if 930 An architecture can select this if it provides an
1477 asm/compiler.h header that should b 931 asm/compiler.h header that should be included after
1478 linux/compiler-*.h in order to over 932 linux/compiler-*.h in order to override macro definitions that those
1479 headers generally provide. 933 headers generally provide.
1480 934
1481 config HAVE_ARCH_PREL32_RELOCATIONS 935 config HAVE_ARCH_PREL32_RELOCATIONS
1482 bool 936 bool
1483 help 937 help
1484 May be selected by an architecture 938 May be selected by an architecture if it supports place-relative
1485 32-bit relocations, both in the too 939 32-bit relocations, both in the toolchain and in the module loader,
1486 in which case relative references c 940 in which case relative references can be used in special sections
1487 for PCI fixup, initcalls etc which 941 for PCI fixup, initcalls etc which are only half the size on 64 bit
1488 architectures, and don't require ru 942 architectures, and don't require runtime relocation on relocatable
1489 kernels. 943 kernels.
1490 944
1491 config ARCH_USE_MEMREMAP_PROT 945 config ARCH_USE_MEMREMAP_PROT
1492 bool 946 bool
1493 947
1494 config LOCK_EVENT_COUNTS 948 config LOCK_EVENT_COUNTS
1495 bool "Locking event counts collection 949 bool "Locking event counts collection"
1496 depends on DEBUG_FS 950 depends on DEBUG_FS
1497 help 951 help
1498 Enable light-weight counting of var 952 Enable light-weight counting of various locking related events
1499 in the system with minimal performa 953 in the system with minimal performance impact. This reduces
1500 the chance of application behavior 954 the chance of application behavior change because of timing
1501 differences. The counts are reporte 955 differences. The counts are reported via debugfs.
1502 956
1503 # Select if the architecture has support for 957 # Select if the architecture has support for applying RELR relocations.
1504 config ARCH_HAS_RELR 958 config ARCH_HAS_RELR
1505 bool 959 bool
1506 960
1507 config RELR 961 config RELR
1508 bool "Use RELR relocation packing" 962 bool "Use RELR relocation packing"
1509 depends on ARCH_HAS_RELR && TOOLS_SUP 963 depends on ARCH_HAS_RELR && TOOLS_SUPPORT_RELR
1510 default y 964 default y
1511 help 965 help
1512 Store the kernel's dynamic relocati 966 Store the kernel's dynamic relocations in the RELR relocation packing
1513 format. Requires a compatible linke 967 format. Requires a compatible linker (LLD supports this feature), as
1514 well as compatible NM and OBJCOPY u 968 well as compatible NM and OBJCOPY utilities (llvm-nm and llvm-objcopy
1515 are compatible). 969 are compatible).
1516 970
1517 config ARCH_HAS_MEM_ENCRYPT 971 config ARCH_HAS_MEM_ENCRYPT
1518 bool 972 bool
1519 973
1520 config ARCH_HAS_CC_PLATFORM <<
1521 bool <<
1522 <<
1523 config HAVE_SPARSE_SYSCALL_NR 974 config HAVE_SPARSE_SYSCALL_NR
1524 bool !! 975 bool
1525 help !! 976 help
1526 An architecture should select this !! 977 An architecture should select this if its syscall numbering is sparse
1527 to save space. For example, MIPS ar 978 to save space. For example, MIPS architecture has a syscall array with
1528 entries at 4000, 5000 and 6000 loca 979 entries at 4000, 5000 and 6000 locations. This option turns on syscall
1529 related optimizations for a given a 980 related optimizations for a given architecture.
1530 981
1531 config ARCH_HAS_VDSO_DATA 982 config ARCH_HAS_VDSO_DATA
1532 bool 983 bool
1533 984
1534 config HAVE_STATIC_CALL <<
1535 bool <<
1536 <<
1537 config HAVE_STATIC_CALL_INLINE <<
1538 bool <<
1539 depends on HAVE_STATIC_CALL <<
1540 select OBJTOOL <<
1541 <<
1542 config HAVE_PREEMPT_DYNAMIC <<
1543 bool <<
1544 <<
1545 config HAVE_PREEMPT_DYNAMIC_CALL <<
1546 bool <<
1547 depends on HAVE_STATIC_CALL <<
1548 select HAVE_PREEMPT_DYNAMIC <<
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 <<
1568 An architecture should select this <<
1569 model being selected at boot time u <<
1570 <<
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 <<
1580 config ARCH_WANT_LD_ORPHAN_WARN <<
1581 bool <<
1582 help <<
1583 An arch should select this symbol o <<
1584 included, size-asserted, or discard <<
1585 important because we never want exp <<
1586 by the linker, since the locations <<
1587 versions. <<
1588 <<
1589 config HAVE_ARCH_PFN_VALID <<
1590 bool <<
1591 <<
1592 config ARCH_SUPPORTS_DEBUG_PAGEALLOC <<
1593 bool <<
1594 <<
1595 config ARCH_SUPPORTS_PAGE_TABLE_CHECK <<
1596 bool <<
1597 <<
1598 config ARCH_SPLIT_ARG64 <<
1599 bool <<
1600 help <<
1601 If a 32-bit architecture requires 6 <<
1602 pairs of 32-bit arguments, select t <<
1603 <<
1604 config ARCH_HAS_ELFCORE_COMPAT <<
1605 bool <<
1606 <<
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" 985 source "kernel/gcov/Kconfig"
1643 986
1644 source "scripts/gcc-plugins/Kconfig" 987 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 988
1685 endmenu 989 endmenu
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