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 menu "General architecture-dependent options" 12 menu "General architecture-dependent options"
21 13
22 config ARCH_HAS_SUBPAGE_FAULTS !! 14 config CRASH_CORE
23 bool 15 bool
24 help <<
25 Select if the architecture can check <<
26 granularity (e.g. arm64 MTE). The pr <<
27 must be implemented. <<
28 16
29 config HOTPLUG_SMT !! 17 config KEXEC_CORE
>> 18 select CRASH_CORE
30 bool 19 bool
31 20
32 config SMT_NUM_THREADS_DYNAMIC !! 21 config KEXEC_ELF
33 bool 22 bool
34 23
35 # Selected by HOTPLUG_CORE_SYNC_DEAD or HOTPLU !! 24 config HAVE_IMA_KEXEC
36 config HOTPLUG_CORE_SYNC <<
37 bool 25 bool
38 26
39 # Basic CPU dead synchronization selected by a !! 27 config SET_FS
40 config HOTPLUG_CORE_SYNC_DEAD <<
41 bool 28 bool
42 select HOTPLUG_CORE_SYNC <<
43 29
44 # Full CPU synchronization with alive state se !! 30 config HOTPLUG_SMT
45 config HOTPLUG_CORE_SYNC_FULL <<
46 bool 31 bool
47 select HOTPLUG_CORE_SYNC_DEAD if HOTPL <<
48 select HOTPLUG_CORE_SYNC <<
49 32
50 config HOTPLUG_SPLIT_STARTUP !! 33 config GENERIC_ENTRY
51 bool !! 34 bool
52 select HOTPLUG_CORE_SYNC_FULL <<
53 35
54 config HOTPLUG_PARALLEL !! 36 config OPROFILE
55 bool !! 37 tristate "OProfile system profiling"
56 select HOTPLUG_SPLIT_STARTUP !! 38 depends on PROFILING
>> 39 depends on HAVE_OPROFILE
>> 40 select RING_BUFFER
>> 41 select RING_BUFFER_ALLOW_SWAP
>> 42 help
>> 43 OProfile is a profiling system capable of profiling the
>> 44 whole system, include the kernel, kernel modules, libraries,
>> 45 and applications.
57 46
58 config GENERIC_ENTRY !! 47 If unsure, say N.
>> 48
>> 49 config OPROFILE_EVENT_MULTIPLEX
>> 50 bool "OProfile multiplexing support (EXPERIMENTAL)"
>> 51 default n
>> 52 depends on OPROFILE && X86
>> 53 help
>> 54 The number of hardware counters is limited. The multiplexing
>> 55 feature enables OProfile to gather more events than counters
>> 56 are provided by the hardware. This is realized by switching
>> 57 between events at a user specified time interval.
>> 58
>> 59 If unsure, say N.
>> 60
>> 61 config HAVE_OPROFILE
59 bool 62 bool
60 63
>> 64 config OPROFILE_NMI_TIMER
>> 65 def_bool y
>> 66 depends on PERF_EVENTS && HAVE_PERF_EVENTS_NMI && !PPC64
>> 67
61 config KPROBES 68 config KPROBES
62 bool "Kprobes" 69 bool "Kprobes"
>> 70 depends on MODULES
63 depends on HAVE_KPROBES 71 depends on HAVE_KPROBES
64 select KALLSYMS 72 select KALLSYMS
65 select EXECMEM <<
66 select NEED_TASKS_RCU <<
67 help 73 help
68 Kprobes allows you to trap at almost 74 Kprobes allows you to trap at almost any kernel address and
69 execute a callback function. regist 75 execute a callback function. register_kprobe() establishes
70 a probepoint and specifies the callb 76 a probepoint and specifies the callback. Kprobes is useful
71 for kernel debugging, non-intrusive 77 for kernel debugging, non-intrusive instrumentation and testing.
72 If in doubt, say "N". 78 If in doubt, say "N".
73 79
74 config JUMP_LABEL 80 config JUMP_LABEL
75 bool "Optimize very unlikely/likely br 81 bool "Optimize very unlikely/likely branches"
76 depends on HAVE_ARCH_JUMP_LABEL 82 depends on HAVE_ARCH_JUMP_LABEL
77 select OBJTOOL if HAVE_JUMP_LABEL_HACK !! 83 depends on CC_HAS_ASM_GOTO
78 help 84 help
79 This option enables a transparent br !! 85 This option enables a transparent branch optimization that
80 makes certain almost-always-true or !! 86 makes certain almost-always-true or almost-always-false branch
81 conditions even cheaper to execute w !! 87 conditions even cheaper to execute within the kernel.
82 !! 88
83 Certain performance-sensitive kernel !! 89 Certain performance-sensitive kernel code, such as trace points,
84 scheduler functionality, networking !! 90 scheduler functionality, networking code and KVM have such
85 branches and include support for thi !! 91 branches and include support for this optimization technique.
86 !! 92
87 If it is detected that the compiler !! 93 If it is detected that the compiler has support for "asm goto",
88 the kernel will compile such branche !! 94 the kernel will compile such branches with just a nop
89 instruction. When the condition flag !! 95 instruction. When the condition flag is toggled to true, the
90 nop will be converted to a jump inst !! 96 nop will be converted to a jump instruction to execute the
91 conditional block of instructions. !! 97 conditional block of instructions.
92 !! 98
93 This technique lowers overhead and s !! 99 This technique lowers overhead and stress on the branch prediction
94 of the processor and generally makes !! 100 of the processor and generally makes the kernel faster. The update
95 of the condition is slower, but thos !! 101 of the condition is slower, but those are always very rare.
96 102
97 ( On 32-bit x86, the necessary optio !! 103 ( On 32-bit x86, the necessary options added to the compiler
98 flags may increase the size of the !! 104 flags may increase the size of the kernel slightly. )
99 105
100 config STATIC_KEYS_SELFTEST 106 config STATIC_KEYS_SELFTEST
101 bool "Static key selftest" 107 bool "Static key selftest"
102 depends on JUMP_LABEL 108 depends on JUMP_LABEL
103 help 109 help
104 Boot time self-test of the branch pa 110 Boot time self-test of the branch patching code.
105 111
106 config STATIC_CALL_SELFTEST 112 config STATIC_CALL_SELFTEST
107 bool "Static call selftest" 113 bool "Static call selftest"
108 depends on HAVE_STATIC_CALL 114 depends on HAVE_STATIC_CALL
109 help 115 help
110 Boot time self-test of the call patc 116 Boot time self-test of the call patching code.
111 117
112 config OPTPROBES 118 config OPTPROBES
113 def_bool y 119 def_bool y
114 depends on KPROBES && HAVE_OPTPROBES 120 depends on KPROBES && HAVE_OPTPROBES
115 select NEED_TASKS_RCU !! 121 select TASKS_RCU if PREEMPTION
116 122
117 config KPROBES_ON_FTRACE 123 config KPROBES_ON_FTRACE
118 def_bool y 124 def_bool y
119 depends on KPROBES && HAVE_KPROBES_ON_ 125 depends on KPROBES && HAVE_KPROBES_ON_FTRACE
120 depends on DYNAMIC_FTRACE_WITH_REGS 126 depends on DYNAMIC_FTRACE_WITH_REGS
121 help 127 help
122 If function tracer is enabled and th !! 128 If function tracer is enabled and the arch supports full
123 passing of pt_regs to function traci !! 129 passing of pt_regs to function tracing, then kprobes can
124 optimize on top of function tracing. !! 130 optimize on top of function tracing.
125 131
126 config UPROBES 132 config UPROBES
127 def_bool n 133 def_bool n
128 depends on ARCH_SUPPORTS_UPROBES 134 depends on ARCH_SUPPORTS_UPROBES
129 help 135 help
130 Uprobes is the user-space counterpar 136 Uprobes is the user-space counterpart to kprobes: they
131 enable instrumentation applications 137 enable instrumentation applications (such as 'perf probe')
132 to establish unintrusive probes in u 138 to establish unintrusive probes in user-space binaries and
133 libraries, by executing handler func 139 libraries, by executing handler functions when the probes
134 are hit by user-space applications. 140 are hit by user-space applications.
135 141
136 ( These probes come in the form of s 142 ( These probes come in the form of single-byte breakpoints,
137 managed by the kernel and kept tra 143 managed by the kernel and kept transparent to the probed
138 application. ) 144 application. )
139 145
140 config HAVE_64BIT_ALIGNED_ACCESS 146 config HAVE_64BIT_ALIGNED_ACCESS
141 def_bool 64BIT && !HAVE_EFFICIENT_UNAL 147 def_bool 64BIT && !HAVE_EFFICIENT_UNALIGNED_ACCESS
142 help 148 help
143 Some architectures require 64 bit ac 149 Some architectures require 64 bit accesses to be 64 bit
144 aligned, which also requires structs 150 aligned, which also requires structs containing 64 bit values
145 to be 64 bit aligned too. This inclu 151 to be 64 bit aligned too. This includes some 32 bit
146 architectures which can do 64 bit ac 152 architectures which can do 64 bit accesses, as well as 64 bit
147 architectures without unaligned acce 153 architectures without unaligned access.
148 154
149 This symbol should be selected by an 155 This symbol should be selected by an architecture if 64 bit
150 accesses are required to be 64 bit a 156 accesses are required to be 64 bit aligned in this way even
151 though it is not a 64 bit architectu 157 though it is not a 64 bit architecture.
152 158
153 See Documentation/core-api/unaligned !! 159 See Documentation/unaligned-memory-access.txt for more
154 more information on the topic of una !! 160 information on the topic of unaligned memory accesses.
155 161
156 config HAVE_EFFICIENT_UNALIGNED_ACCESS 162 config HAVE_EFFICIENT_UNALIGNED_ACCESS
157 bool 163 bool
158 help 164 help
159 Some architectures are unable to per 165 Some architectures are unable to perform unaligned accesses
160 without the use of get_unaligned/put 166 without the use of get_unaligned/put_unaligned. Others are
161 unable to perform such accesses effi 167 unable to perform such accesses efficiently (e.g. trap on
162 unaligned access and require fixing 168 unaligned access and require fixing it up in the exception
163 handler.) 169 handler.)
164 170
165 This symbol should be selected by an 171 This symbol should be selected by an architecture if it can
166 perform unaligned accesses efficient 172 perform unaligned accesses efficiently to allow different
167 code paths to be selected for these 173 code paths to be selected for these cases. Some network
168 drivers, for example, could opt to n 174 drivers, for example, could opt to not fix up alignment
169 problems with received packets if do 175 problems with received packets if doing so would not help
170 much. 176 much.
171 177
172 See Documentation/core-api/unaligned 178 See Documentation/core-api/unaligned-memory-access.rst for more
173 information on the topic of unaligne 179 information on the topic of unaligned memory accesses.
174 180
175 config ARCH_USE_BUILTIN_BSWAP 181 config ARCH_USE_BUILTIN_BSWAP
176 bool 182 bool
177 help 183 help
178 Modern versions of GCC (since 4.4) h !! 184 Modern versions of GCC (since 4.4) have builtin functions
179 for handling byte-swapping. Using th !! 185 for handling byte-swapping. Using these, instead of the old
180 inline assembler that the architectu !! 186 inline assembler that the architecture code provides in the
181 __arch_bswapXX() macros, allows the !! 187 __arch_bswapXX() macros, allows the compiler to see what's
182 happening and offers more opportunit !! 188 happening and offers more opportunity for optimisation. In
183 particular, the compiler will be abl !! 189 particular, the compiler will be able to combine the byteswap
184 with a nearby load or store and use !! 190 with a nearby load or store and use load-and-swap or
185 store-and-swap instructions if the a !! 191 store-and-swap instructions if the architecture has them. It
186 should almost *never* result in code !! 192 should almost *never* result in code which is worse than the
187 hand-coded assembler in <asm/swab.h> !! 193 hand-coded assembler in <asm/swab.h>. But just in case it
188 does, the use of the builtins is opt !! 194 does, the use of the builtins is optional.
189 !! 195
190 Any architecture with load-and-swap !! 196 Any architecture with load-and-swap or store-and-swap
191 instructions should set this. And it !! 197 instructions should set this. And it shouldn't hurt to set it
192 on architectures that don't have suc !! 198 on architectures that don't have such instructions.
193 199
194 config KRETPROBES 200 config KRETPROBES
195 def_bool y 201 def_bool y
196 depends on KPROBES && (HAVE_KRETPROBES !! 202 depends on KPROBES && HAVE_KRETPROBES
197 <<
198 config KRETPROBE_ON_RETHOOK <<
199 def_bool y <<
200 depends on HAVE_RETHOOK <<
201 depends on KRETPROBES <<
202 select RETHOOK <<
203 203
204 config USER_RETURN_NOTIFIER 204 config USER_RETURN_NOTIFIER
205 bool 205 bool
206 depends on HAVE_USER_RETURN_NOTIFIER 206 depends on HAVE_USER_RETURN_NOTIFIER
207 help 207 help
208 Provide a kernel-internal notificati 208 Provide a kernel-internal notification when a cpu is about to
209 switch to user mode. 209 switch to user mode.
210 210
211 config HAVE_IOREMAP_PROT 211 config HAVE_IOREMAP_PROT
212 bool 212 bool
213 213
214 config HAVE_KPROBES 214 config HAVE_KPROBES
215 bool 215 bool
216 216
217 config HAVE_KRETPROBES 217 config HAVE_KRETPROBES
218 bool 218 bool
219 219
220 config HAVE_OPTPROBES 220 config HAVE_OPTPROBES
221 bool 221 bool
222 222
223 config HAVE_KPROBES_ON_FTRACE 223 config HAVE_KPROBES_ON_FTRACE
224 bool 224 bool
225 225
226 config ARCH_CORRECT_STACKTRACE_ON_KRETPROBE <<
227 bool <<
228 help <<
229 Since kretprobes modifies return add <<
230 stacktrace may see the kretprobe tra <<
231 of correct one. If the architecture <<
232 unwinder can adjust such entries, se <<
233 <<
234 config HAVE_FUNCTION_ERROR_INJECTION 226 config HAVE_FUNCTION_ERROR_INJECTION
235 bool 227 bool
236 228
237 config HAVE_NMI 229 config HAVE_NMI
238 bool 230 bool
239 231
240 config HAVE_FUNCTION_DESCRIPTORS <<
241 bool <<
242 <<
243 config TRACE_IRQFLAGS_SUPPORT <<
244 bool <<
245 <<
246 config TRACE_IRQFLAGS_NMI_SUPPORT <<
247 bool <<
248 <<
249 # 232 #
250 # An arch should select this if it provides al 233 # An arch should select this if it provides all these things:
251 # 234 #
252 # task_pt_regs() in asm/process 235 # task_pt_regs() in asm/processor.h or asm/ptrace.h
253 # arch_has_single_step() if there is ha 236 # arch_has_single_step() if there is hardware single-step support
254 # arch_has_block_step() if there is ha 237 # arch_has_block_step() if there is hardware block-step support
255 # asm/syscall.h supplying asm- 238 # asm/syscall.h supplying asm-generic/syscall.h interface
256 # linux/regset.h user_regset in 239 # linux/regset.h user_regset interfaces
257 # CORE_DUMP_USE_REGSET #define'd in l 240 # CORE_DUMP_USE_REGSET #define'd in linux/elf.h
258 # TIF_SYSCALL_TRACE calls ptrace_r !! 241 # TIF_SYSCALL_TRACE calls tracehook_report_syscall_{entry,exit}
259 # TIF_NOTIFY_RESUME calls resume_u !! 242 # TIF_NOTIFY_RESUME calls tracehook_notify_resume()
>> 243 # signal delivery calls tracehook_signal_handler()
260 # 244 #
261 config HAVE_ARCH_TRACEHOOK 245 config HAVE_ARCH_TRACEHOOK
262 bool 246 bool
263 247
264 config HAVE_DMA_CONTIGUOUS 248 config HAVE_DMA_CONTIGUOUS
265 bool 249 bool
266 250
267 config GENERIC_SMP_IDLE_THREAD 251 config GENERIC_SMP_IDLE_THREAD
268 bool 252 bool
269 253
270 config GENERIC_IDLE_POLL_SETUP 254 config GENERIC_IDLE_POLL_SETUP
271 bool 255 bool
272 256
273 config ARCH_HAS_FORTIFY_SOURCE 257 config ARCH_HAS_FORTIFY_SOURCE
274 bool 258 bool
275 help 259 help
276 An architecture should select this w 260 An architecture should select this when it can successfully
277 build and run with CONFIG_FORTIFY_SO 261 build and run with CONFIG_FORTIFY_SOURCE.
278 262
279 # 263 #
280 # Select if the arch provides a historic keepi 264 # Select if the arch provides a historic keepinit alias for the retain_initrd
281 # command line option 265 # command line option
282 # 266 #
283 config ARCH_HAS_KEEPINITRD 267 config ARCH_HAS_KEEPINITRD
284 bool 268 bool
285 269
286 # Select if arch has all set_memory_ro/rw/x/nx 270 # Select if arch has all set_memory_ro/rw/x/nx() functions in asm/cacheflush.h
287 config ARCH_HAS_SET_MEMORY 271 config ARCH_HAS_SET_MEMORY
288 bool 272 bool
289 273
290 # Select if arch has all set_direct_map_invali 274 # Select if arch has all set_direct_map_invalid/default() functions
291 config ARCH_HAS_SET_DIRECT_MAP 275 config ARCH_HAS_SET_DIRECT_MAP
292 bool 276 bool
293 277
294 # 278 #
295 # Select if the architecture provides the arch 279 # Select if the architecture provides the arch_dma_set_uncached symbol to
296 # either provide an uncached segment alias for 280 # either provide an uncached segment alias for a DMA allocation, or
297 # to remap the page tables in place. 281 # to remap the page tables in place.
298 # 282 #
299 config ARCH_HAS_DMA_SET_UNCACHED 283 config ARCH_HAS_DMA_SET_UNCACHED
300 bool 284 bool
301 285
302 # 286 #
303 # Select if the architectures provides the arc 287 # Select if the architectures provides the arch_dma_clear_uncached symbol
304 # to undo an in-place page table remap for unc 288 # to undo an in-place page table remap for uncached access.
305 # 289 #
306 config ARCH_HAS_DMA_CLEAR_UNCACHED 290 config ARCH_HAS_DMA_CLEAR_UNCACHED
307 bool 291 bool
308 292
309 config ARCH_HAS_CPU_FINALIZE_INIT !! 293 # Select if arch init_task must go in the __init_task_data section
>> 294 config ARCH_TASK_STRUCT_ON_STACK
310 bool 295 bool
311 296
312 # The architecture has a per-task state that i !! 297 # Select if arch has its private alloc_task_struct() function
313 config ARCH_HAS_CPU_PASID !! 298 config ARCH_TASK_STRUCT_ALLOCATOR
314 bool 299 bool
315 select IOMMU_MM_DATA <<
316 300
317 config HAVE_ARCH_THREAD_STRUCT_WHITELIST 301 config HAVE_ARCH_THREAD_STRUCT_WHITELIST
318 bool 302 bool
>> 303 depends on !ARCH_TASK_STRUCT_ALLOCATOR
319 help 304 help
320 An architecture should select this t 305 An architecture should select this to provide hardened usercopy
321 knowledge about what region of the t 306 knowledge about what region of the thread_struct should be
322 whitelisted for copying to userspace 307 whitelisted for copying to userspace. Normally this is only the
323 FPU registers. Specifically, arch_th 308 FPU registers. Specifically, arch_thread_struct_whitelist()
324 should be implemented. Without this, 309 should be implemented. Without this, the entire thread_struct
325 field in task_struct will be left wh 310 field in task_struct will be left whitelisted.
326 311
327 # Select if arch wants to size task_struct dyn !! 312 # Select if arch has its private alloc_thread_stack() function
328 config ARCH_WANTS_DYNAMIC_TASK_STRUCT !! 313 config ARCH_THREAD_STACK_ALLOCATOR
329 bool 314 bool
330 315
331 config ARCH_WANTS_NO_INSTR !! 316 # Select if arch wants to size task_struct dynamically via arch_task_struct_size:
>> 317 config ARCH_WANTS_DYNAMIC_TASK_STRUCT
332 bool 318 bool
333 help <<
334 An architecture should select this i <<
335 functions to denote that the toolcha <<
336 functions and is required for correc <<
337 319
338 config ARCH_32BIT_OFF_T 320 config ARCH_32BIT_OFF_T
339 bool 321 bool
340 depends on !64BIT 322 depends on !64BIT
341 help 323 help
342 All new 32-bit architectures should 324 All new 32-bit architectures should have 64-bit off_t type on
343 userspace side which corresponds to 325 userspace side which corresponds to the loff_t kernel type. This
344 is the requirement for modern ABIs. 326 is the requirement for modern ABIs. Some existing architectures
345 still support 32-bit off_t. This opt 327 still support 32-bit off_t. This option is enabled for all such
346 architectures explicitly. 328 architectures explicitly.
347 329
348 # Selected by 64 bit architectures which have <<
349 config ARCH_32BIT_USTAT_F_TINODE <<
350 bool <<
351 <<
352 config HAVE_ASM_MODVERSIONS 330 config HAVE_ASM_MODVERSIONS
353 bool 331 bool
354 help 332 help
355 This symbol should be selected by an 333 This symbol should be selected by an architecture if it provides
356 <asm/asm-prototypes.h> to support th 334 <asm/asm-prototypes.h> to support the module versioning for symbols
357 exported from assembly code. 335 exported from assembly code.
358 336
359 config HAVE_REGS_AND_STACK_ACCESS_API 337 config HAVE_REGS_AND_STACK_ACCESS_API
360 bool 338 bool
361 help 339 help
362 This symbol should be selected by an 340 This symbol should be selected by an architecture if it supports
363 the API needed to access registers a 341 the API needed to access registers and stack entries from pt_regs,
364 declared in asm/ptrace.h 342 declared in asm/ptrace.h
365 For example the kprobes-based event 343 For example the kprobes-based event tracer needs this API.
366 344
367 config HAVE_RSEQ 345 config HAVE_RSEQ
368 bool 346 bool
369 depends on HAVE_REGS_AND_STACK_ACCESS_ 347 depends on HAVE_REGS_AND_STACK_ACCESS_API
370 help 348 help
371 This symbol should be selected by an 349 This symbol should be selected by an architecture if it
372 supports an implementation of restar 350 supports an implementation of restartable sequences.
373 351
374 config HAVE_RUST <<
375 bool <<
376 help <<
377 This symbol should be selected by an <<
378 supports Rust. <<
379 <<
380 config HAVE_FUNCTION_ARG_ACCESS_API 352 config HAVE_FUNCTION_ARG_ACCESS_API
381 bool 353 bool
382 help 354 help
383 This symbol should be selected by an 355 This symbol should be selected by an architecture if it supports
384 the API needed to access function ar 356 the API needed to access function arguments from pt_regs,
385 declared in asm/ptrace.h 357 declared in asm/ptrace.h
386 358
387 config HAVE_HW_BREAKPOINT 359 config HAVE_HW_BREAKPOINT
388 bool 360 bool
389 depends on PERF_EVENTS 361 depends on PERF_EVENTS
390 362
391 config HAVE_MIXED_BREAKPOINTS_REGS 363 config HAVE_MIXED_BREAKPOINTS_REGS
392 bool 364 bool
393 depends on HAVE_HW_BREAKPOINT 365 depends on HAVE_HW_BREAKPOINT
394 help 366 help
395 Depending on the arch implementation 367 Depending on the arch implementation of hardware breakpoints,
396 some of them have separate registers 368 some of them have separate registers for data and instruction
397 breakpoints addresses, others have m 369 breakpoints addresses, others have mixed registers to store
398 them but define the access type in a 370 them but define the access type in a control register.
399 Select this option if your arch impl 371 Select this option if your arch implements breakpoints under the
400 latter fashion. 372 latter fashion.
401 373
402 config HAVE_USER_RETURN_NOTIFIER 374 config HAVE_USER_RETURN_NOTIFIER
403 bool 375 bool
404 376
405 config HAVE_PERF_EVENTS_NMI 377 config HAVE_PERF_EVENTS_NMI
406 bool 378 bool
407 help 379 help
408 System hardware can generate an NMI 380 System hardware can generate an NMI using the perf event
409 subsystem. Also has support for cal 381 subsystem. Also has support for calculating CPU cycle events
410 to determine how many clock cycles i 382 to determine how many clock cycles in a given period.
411 383
412 config HAVE_HARDLOCKUP_DETECTOR_PERF 384 config HAVE_HARDLOCKUP_DETECTOR_PERF
413 bool 385 bool
414 depends on HAVE_PERF_EVENTS_NMI 386 depends on HAVE_PERF_EVENTS_NMI
415 help 387 help
416 The arch chooses to use the generic 388 The arch chooses to use the generic perf-NMI-based hardlockup
417 detector. Must define HAVE_PERF_EVEN 389 detector. Must define HAVE_PERF_EVENTS_NMI.
418 390
419 config HAVE_HARDLOCKUP_DETECTOR_ARCH !! 391 config HAVE_NMI_WATCHDOG
>> 392 depends on HAVE_NMI
420 bool 393 bool
421 help 394 help
422 The arch provides its own hardlockup !! 395 The arch provides a low level NMI watchdog. It provides
423 of the generic ones. !! 396 asm/nmi.h, and defines its own arch_touch_nmi_watchdog().
424 397
425 It uses the same command line parame !! 398 config HAVE_HARDLOCKUP_DETECTOR_ARCH
426 as the generic hardlockup detectors. !! 399 bool
>> 400 select HAVE_NMI_WATCHDOG
>> 401 help
>> 402 The arch chooses to provide its own hardlockup detector, which is
>> 403 a superset of the HAVE_NMI_WATCHDOG. It also conforms to config
>> 404 interfaces and parameters provided by hardlockup detector subsystem.
427 405
428 config HAVE_PERF_REGS 406 config HAVE_PERF_REGS
429 bool 407 bool
430 help 408 help
431 Support selective register dumps for 409 Support selective register dumps for perf events. This includes
432 bit-mapping of each registers and a 410 bit-mapping of each registers and a unique architecture id.
433 411
434 config HAVE_PERF_USER_STACK_DUMP 412 config HAVE_PERF_USER_STACK_DUMP
435 bool 413 bool
436 help 414 help
437 Support user stack dumps for perf ev 415 Support user stack dumps for perf event samples. This needs
438 access to the user stack pointer whi 416 access to the user stack pointer which is not unified across
439 architectures. 417 architectures.
440 418
441 config HAVE_ARCH_JUMP_LABEL 419 config HAVE_ARCH_JUMP_LABEL
442 bool 420 bool
443 421
444 config HAVE_ARCH_JUMP_LABEL_RELATIVE 422 config HAVE_ARCH_JUMP_LABEL_RELATIVE
445 bool 423 bool
446 424
447 config MMU_GATHER_TABLE_FREE 425 config MMU_GATHER_TABLE_FREE
448 bool 426 bool
449 427
450 config MMU_GATHER_RCU_TABLE_FREE 428 config MMU_GATHER_RCU_TABLE_FREE
451 bool 429 bool
452 select MMU_GATHER_TABLE_FREE 430 select MMU_GATHER_TABLE_FREE
453 431
454 config MMU_GATHER_PAGE_SIZE 432 config MMU_GATHER_PAGE_SIZE
455 bool 433 bool
456 434
457 config MMU_GATHER_NO_RANGE 435 config MMU_GATHER_NO_RANGE
458 bool 436 bool
459 select MMU_GATHER_MERGE_VMAS <<
460 <<
461 config MMU_GATHER_NO_FLUSH_CACHE <<
462 bool <<
463 <<
464 config MMU_GATHER_MERGE_VMAS <<
465 bool <<
466 437
467 config MMU_GATHER_NO_GATHER 438 config MMU_GATHER_NO_GATHER
468 bool 439 bool
469 depends on MMU_GATHER_TABLE_FREE 440 depends on MMU_GATHER_TABLE_FREE
470 441
471 config ARCH_WANT_IRQS_OFF_ACTIVATE_MM 442 config ARCH_WANT_IRQS_OFF_ACTIVATE_MM
472 bool 443 bool
473 help 444 help
474 Temporary select until all architect 445 Temporary select until all architectures can be converted to have
475 irqs disabled over activate_mm. Arch 446 irqs disabled over activate_mm. Architectures that do IPI based TLB
476 shootdowns should enable this. 447 shootdowns should enable this.
477 448
478 # Use normal mm refcounting for MMU_LAZY_TLB k <<
479 # MMU_LAZY_TLB_REFCOUNT=n can improve the scal <<
480 # to/from kernel threads when the same mm is r <<
481 # multi-threaded application), by reducing con <<
482 # <<
483 # This can be disabled if the architecture ens <<
484 # "lazy tlb" beyond its final refcount (i.e., <<
485 # or its kernel page tables). This could be ar <<
486 # final exit(2) TLB flush, for example. <<
487 # <<
488 # To implement this, an arch *must*: <<
489 # Ensure the _lazy_tlb variants of mmgrab/mmdr <<
490 # the lazy tlb reference of a kthread's ->acti <<
491 # converted already). <<
492 config MMU_LAZY_TLB_REFCOUNT <<
493 def_bool y <<
494 depends on !MMU_LAZY_TLB_SHOOTDOWN <<
495 <<
496 # This option allows MMU_LAZY_TLB_REFCOUNT=n. <<
497 # mm as a lazy tlb beyond its last reference c <<
498 # users before the mm is deallocated. __mmdrop <<
499 # be using the mm as a lazy tlb, so that they <<
500 # init_mm for their active mm. mm_cpumask(mm) <<
501 # may be using mm as a lazy tlb mm. <<
502 # <<
503 # To implement this, an arch *must*: <<
504 # - At the time of the final mmdrop of the mm, <<
505 # at least all possible CPUs in which the mm <<
506 # - It must meet the requirements for MMU_LAZY <<
507 config MMU_LAZY_TLB_SHOOTDOWN <<
508 bool <<
509 <<
510 config ARCH_HAVE_NMI_SAFE_CMPXCHG 449 config ARCH_HAVE_NMI_SAFE_CMPXCHG
511 bool 450 bool
512 451
513 config ARCH_HAVE_EXTRA_ELF_NOTES <<
514 bool <<
515 help <<
516 An architecture should select this i <<
517 arch-specific ELF note section to co <<
518 functions: elf_coredump_extra_notes_ <<
519 elf_coredump_extra_notes_write() whi <<
520 dumper. <<
521 <<
522 config ARCH_HAS_NMI_SAFE_THIS_CPU_OPS <<
523 bool <<
524 <<
525 config HAVE_ALIGNED_STRUCT_PAGE 452 config HAVE_ALIGNED_STRUCT_PAGE
526 bool 453 bool
527 help 454 help
528 This makes sure that struct pages ar 455 This makes sure that struct pages are double word aligned and that
529 e.g. the SLUB allocator can perform 456 e.g. the SLUB allocator can perform double word atomic operations
530 on a struct page for better performa 457 on a struct page for better performance. However selecting this
531 might increase the size of a struct 458 might increase the size of a struct page by a word.
532 459
533 config HAVE_CMPXCHG_LOCAL 460 config HAVE_CMPXCHG_LOCAL
534 bool 461 bool
535 462
536 config HAVE_CMPXCHG_DOUBLE 463 config HAVE_CMPXCHG_DOUBLE
537 bool 464 bool
538 465
539 config ARCH_WEAK_RELEASE_ACQUIRE 466 config ARCH_WEAK_RELEASE_ACQUIRE
540 bool 467 bool
541 468
542 config ARCH_WANT_IPC_PARSE_VERSION 469 config ARCH_WANT_IPC_PARSE_VERSION
543 bool 470 bool
544 471
545 config ARCH_WANT_COMPAT_IPC_PARSE_VERSION 472 config ARCH_WANT_COMPAT_IPC_PARSE_VERSION
546 bool 473 bool
547 474
548 config ARCH_WANT_OLD_COMPAT_IPC 475 config ARCH_WANT_OLD_COMPAT_IPC
549 select ARCH_WANT_COMPAT_IPC_PARSE_VERS 476 select ARCH_WANT_COMPAT_IPC_PARSE_VERSION
550 bool 477 bool
551 478
552 config HAVE_ARCH_SECCOMP 479 config HAVE_ARCH_SECCOMP
553 bool 480 bool
554 help 481 help
555 An arch should select this symbol to 482 An arch should select this symbol to support seccomp mode 1 (the fixed
556 syscall policy), and must provide an 483 syscall policy), and must provide an overrides for __NR_seccomp_sigreturn,
557 and compat syscalls if the asm-gener 484 and compat syscalls if the asm-generic/seccomp.h defaults need adjustment:
558 - __NR_seccomp_read_32 485 - __NR_seccomp_read_32
559 - __NR_seccomp_write_32 486 - __NR_seccomp_write_32
560 - __NR_seccomp_exit_32 487 - __NR_seccomp_exit_32
561 - __NR_seccomp_sigreturn_32 488 - __NR_seccomp_sigreturn_32
562 489
563 config HAVE_ARCH_SECCOMP_FILTER 490 config HAVE_ARCH_SECCOMP_FILTER
564 bool 491 bool
565 select HAVE_ARCH_SECCOMP 492 select HAVE_ARCH_SECCOMP
566 help 493 help
567 An arch should select this symbol if 494 An arch should select this symbol if it provides all of these things:
568 - all the requirements for HAVE_ARCH 495 - all the requirements for HAVE_ARCH_SECCOMP
569 - syscall_get_arch() 496 - syscall_get_arch()
570 - syscall_get_arguments() 497 - syscall_get_arguments()
571 - syscall_rollback() 498 - syscall_rollback()
572 - syscall_set_return_value() 499 - syscall_set_return_value()
573 - SIGSYS siginfo_t support 500 - SIGSYS siginfo_t support
574 - secure_computing is called from a 501 - secure_computing is called from a ptrace_event()-safe context
575 - secure_computing return value is c 502 - secure_computing return value is checked and a return value of -1
576 results in the system call being s 503 results in the system call being skipped immediately.
577 - seccomp syscall wired up 504 - seccomp syscall wired up
578 - if !HAVE_SPARSE_SYSCALL_NR, have S 505 - if !HAVE_SPARSE_SYSCALL_NR, have SECCOMP_ARCH_NATIVE,
579 SECCOMP_ARCH_NATIVE_NR, SECCOMP_AR 506 SECCOMP_ARCH_NATIVE_NR, SECCOMP_ARCH_NATIVE_NAME defined. If
580 COMPAT is supported, have the SECC 507 COMPAT is supported, have the SECCOMP_ARCH_COMPAT* defines too.
581 508
582 config SECCOMP 509 config SECCOMP
583 prompt "Enable seccomp to safely execu 510 prompt "Enable seccomp to safely execute untrusted bytecode"
584 def_bool y 511 def_bool y
585 depends on HAVE_ARCH_SECCOMP 512 depends on HAVE_ARCH_SECCOMP
586 help 513 help
587 This kernel feature is useful for nu 514 This kernel feature is useful for number crunching applications
588 that may need to handle untrusted by 515 that may need to handle untrusted bytecode during their
589 execution. By using pipes or other t 516 execution. By using pipes or other transports made available
590 to the process as file descriptors s 517 to the process as file descriptors supporting the read/write
591 syscalls, it's possible to isolate t 518 syscalls, it's possible to isolate those applications in their
592 own address space using seccomp. Onc 519 own address space using seccomp. Once seccomp is enabled via
593 prctl(PR_SET_SECCOMP) or the seccomp 520 prctl(PR_SET_SECCOMP) or the seccomp() syscall, it cannot be
594 disabled and the task is only allowe 521 disabled and the task is only allowed to execute a few safe
595 syscalls defined by each seccomp mod 522 syscalls defined by each seccomp mode.
596 523
597 If unsure, say Y. 524 If unsure, say Y.
598 525
599 config SECCOMP_FILTER 526 config SECCOMP_FILTER
600 def_bool y 527 def_bool y
601 depends on HAVE_ARCH_SECCOMP_FILTER && 528 depends on HAVE_ARCH_SECCOMP_FILTER && SECCOMP && NET
602 help 529 help
603 Enable tasks to build secure computi 530 Enable tasks to build secure computing environments defined
604 in terms of Berkeley Packet Filter p 531 in terms of Berkeley Packet Filter programs which implement
605 task-defined system call filtering p 532 task-defined system call filtering polices.
606 533
607 See Documentation/userspace-api/secc 534 See Documentation/userspace-api/seccomp_filter.rst for details.
608 535
609 config SECCOMP_CACHE_DEBUG 536 config SECCOMP_CACHE_DEBUG
610 bool "Show seccomp filter cache status 537 bool "Show seccomp filter cache status in /proc/pid/seccomp_cache"
611 depends on SECCOMP_FILTER && !HAVE_SPA 538 depends on SECCOMP_FILTER && !HAVE_SPARSE_SYSCALL_NR
612 depends on PROC_FS 539 depends on PROC_FS
613 help 540 help
614 This enables the /proc/pid/seccomp_c 541 This enables the /proc/pid/seccomp_cache interface to monitor
615 seccomp cache data. The file format 542 seccomp cache data. The file format is subject to change. Reading
616 the file requires CAP_SYS_ADMIN. 543 the file requires CAP_SYS_ADMIN.
617 544
618 This option is for debugging only. E 545 This option is for debugging only. Enabling presents the risk that
619 an adversary may be able to infer th 546 an adversary may be able to infer the seccomp filter logic.
620 547
621 If unsure, say N. 548 If unsure, say N.
622 549
623 config HAVE_ARCH_STACKLEAK 550 config HAVE_ARCH_STACKLEAK
624 bool 551 bool
625 help 552 help
626 An architecture should select this i 553 An architecture should select this if it has the code which
627 fills the used part of the kernel st 554 fills the used part of the kernel stack with the STACKLEAK_POISON
628 value before returning from system c 555 value before returning from system calls.
629 556
630 config HAVE_STACKPROTECTOR 557 config HAVE_STACKPROTECTOR
631 bool 558 bool
632 help 559 help
633 An arch should select this symbol if 560 An arch should select this symbol if:
634 - it has implemented a stack canary 561 - it has implemented a stack canary (e.g. __stack_chk_guard)
635 562
636 config STACKPROTECTOR 563 config STACKPROTECTOR
637 bool "Stack Protector buffer overflow 564 bool "Stack Protector buffer overflow detection"
638 depends on HAVE_STACKPROTECTOR 565 depends on HAVE_STACKPROTECTOR
639 depends on $(cc-option,-fstack-protect 566 depends on $(cc-option,-fstack-protector)
640 default y 567 default y
641 help 568 help
642 This option turns on the "stack-prot 569 This option turns on the "stack-protector" GCC feature. This
643 feature puts, at the beginning of fu 570 feature puts, at the beginning of functions, a canary value on
644 the stack just before the return add 571 the stack just before the return address, and validates
645 the value just before actually retur 572 the value just before actually returning. Stack based buffer
646 overflows (that need to overwrite th 573 overflows (that need to overwrite this return address) now also
647 overwrite the canary, which gets det 574 overwrite the canary, which gets detected and the attack is then
648 neutralized via a kernel panic. 575 neutralized via a kernel panic.
649 576
650 Functions will have the stack-protec 577 Functions will have the stack-protector canary logic added if they
651 have an 8-byte or larger character a 578 have an 8-byte or larger character array on the stack.
652 579
653 This feature requires gcc version 4. 580 This feature requires gcc version 4.2 or above, or a distribution
654 gcc with the feature backported ("-f 581 gcc with the feature backported ("-fstack-protector").
655 582
656 On an x86 "defconfig" build, this fe 583 On an x86 "defconfig" build, this feature adds canary checks to
657 about 3% of all kernel functions, wh 584 about 3% of all kernel functions, which increases kernel code size
658 by about 0.3%. 585 by about 0.3%.
659 586
660 config STACKPROTECTOR_STRONG 587 config STACKPROTECTOR_STRONG
661 bool "Strong Stack Protector" 588 bool "Strong Stack Protector"
662 depends on STACKPROTECTOR 589 depends on STACKPROTECTOR
663 depends on $(cc-option,-fstack-protect 590 depends on $(cc-option,-fstack-protector-strong)
664 default y 591 default y
665 help 592 help
666 Functions will have the stack-protec 593 Functions will have the stack-protector canary logic added in any
667 of the following conditions: 594 of the following conditions:
668 595
669 - local variable's address used as p 596 - local variable's address used as part of the right hand side of an
670 assignment or function argument 597 assignment or function argument
671 - local variable is an array (or uni 598 - local variable is an array (or union containing an array),
672 regardless of array type or length 599 regardless of array type or length
673 - uses register local variables 600 - uses register local variables
674 601
675 This feature requires gcc version 4. 602 This feature requires gcc version 4.9 or above, or a distribution
676 gcc with the feature backported ("-f 603 gcc with the feature backported ("-fstack-protector-strong").
677 604
678 On an x86 "defconfig" build, this fe 605 On an x86 "defconfig" build, this feature adds canary checks to
679 about 20% of all kernel functions, w 606 about 20% of all kernel functions, which increases the kernel code
680 size by about 2%. 607 size by about 2%.
681 608
682 config ARCH_SUPPORTS_SHADOW_CALL_STACK 609 config ARCH_SUPPORTS_SHADOW_CALL_STACK
683 bool 610 bool
684 help 611 help
685 An architecture should select this i !! 612 An architecture should select this if it supports Clang's Shadow
686 Shadow Call Stack and implements run !! 613 Call Stack and implements runtime support for shadow stack
687 switching. 614 switching.
688 615
689 config SHADOW_CALL_STACK 616 config SHADOW_CALL_STACK
690 bool "Shadow Call Stack" !! 617 bool "Clang Shadow Call Stack"
691 depends on ARCH_SUPPORTS_SHADOW_CALL_S !! 618 depends on CC_IS_CLANG && ARCH_SUPPORTS_SHADOW_CALL_STACK
692 depends on DYNAMIC_FTRACE_WITH_ARGS || !! 619 depends on DYNAMIC_FTRACE_WITH_REGS || !FUNCTION_GRAPH_TRACER
693 depends on MMU !! 620 help
694 help !! 621 This option enables Clang's Shadow Call Stack, which uses a
695 This option enables the compiler's S !! 622 shadow stack to protect function return addresses from being
696 uses a shadow stack to protect funct !! 623 overwritten by an attacker. More information can be found in
697 being overwritten by an attacker. Mo !! 624 Clang's documentation:
698 in the compiler's documentation: <<
699 625
700 - Clang: https://clang.llvm.org/docs !! 626 https://clang.llvm.org/docs/ShadowCallStack.html
701 - GCC: https://gcc.gnu.org/onlinedoc <<
702 627
703 Note that security guarantees in the 628 Note that security guarantees in the kernel differ from the
704 ones documented for user space. The 629 ones documented for user space. The kernel must store addresses
705 of shadow stacks in memory, which me 630 of shadow stacks in memory, which means an attacker capable of
706 reading and writing arbitrary memory 631 reading and writing arbitrary memory may be able to locate them
707 and hijack control flow by modifying 632 and hijack control flow by modifying the stacks.
708 633
709 config DYNAMIC_SCS <<
710 bool <<
711 help <<
712 Set by the arch code if it relies on <<
713 shadow call stack push and pop instr <<
714 compiler. <<
715 <<
716 config LTO <<
717 bool <<
718 help <<
719 Selected if the kernel will be built <<
720 <<
721 config LTO_CLANG <<
722 bool <<
723 select LTO <<
724 help <<
725 Selected if the kernel will be built <<
726 <<
727 config ARCH_SUPPORTS_LTO_CLANG <<
728 bool <<
729 help <<
730 An architecture should select this o <<
731 - compiling with Clang, <<
732 - compiling inline assembly with Cla <<
733 - and linking with LLD. <<
734 <<
735 config ARCH_SUPPORTS_LTO_CLANG_THIN <<
736 bool <<
737 help <<
738 An architecture should select this o <<
739 ThinLTO mode. <<
740 <<
741 config HAS_LTO_CLANG <<
742 def_bool y <<
743 depends on CC_IS_CLANG && LD_IS_LLD && <<
744 depends on $(success,$(NM) --help | he <<
745 depends on $(success,$(AR) --help | he <<
746 depends on ARCH_SUPPORTS_LTO_CLANG <<
747 depends on !FTRACE_MCOUNT_USE_RECORDMC <<
748 # https://github.com/ClangBuiltLinux/l <<
749 depends on (!KASAN || KASAN_HW_TAGS || <<
750 depends on (!KCOV || CLANG_VERSION >= <<
751 depends on !GCOV_KERNEL <<
752 help <<
753 The compiler and Kconfig options sup <<
754 LTO. <<
755 <<
756 choice <<
757 prompt "Link Time Optimization (LTO)" <<
758 default LTO_NONE <<
759 help <<
760 This option enables Link Time Optimi <<
761 compiler to optimize binaries global <<
762 <<
763 If unsure, select LTO_NONE. Note tha <<
764 so it's disabled by default. <<
765 <<
766 config LTO_NONE <<
767 bool "None" <<
768 help <<
769 Build the kernel normally, without L <<
770 <<
771 config LTO_CLANG_FULL <<
772 bool "Clang Full LTO (EXPERIMENTAL)" <<
773 depends on HAS_LTO_CLANG <<
774 depends on !COMPILE_TEST <<
775 select LTO_CLANG <<
776 help <<
777 This option enables Clang's full Lin <<
778 allows the compiler to optimize the <<
779 this option, the compiler generates <<
780 object files, and the actual compila <<
781 the LTO link step, which may take se <<
782 kernel configuration. More informati <<
783 documentation: <<
784 <<
785 https://llvm.org/docs/LinkTimeOpti <<
786 <<
787 During link time, this option can us <<
788 may take much longer than the ThinLT <<
789 <<
790 config LTO_CLANG_THIN <<
791 bool "Clang ThinLTO (EXPERIMENTAL)" <<
792 depends on HAS_LTO_CLANG && ARCH_SUPPO <<
793 select LTO_CLANG <<
794 help <<
795 This option enables Clang's ThinLTO, <<
796 optimization and faster incremental <<
797 CONFIG_LTO_CLANG_FULL option. More i <<
798 from Clang's documentation: <<
799 <<
800 https://clang.llvm.org/docs/ThinLT <<
801 <<
802 If unsure, say Y. <<
803 endchoice <<
804 <<
805 config ARCH_SUPPORTS_CFI_CLANG <<
806 bool <<
807 help <<
808 An architecture should select this o <<
809 Control-Flow Integrity (CFI) checkin <<
810 <<
811 config ARCH_USES_CFI_TRAPS <<
812 bool <<
813 <<
814 config CFI_CLANG <<
815 bool "Use Clang's Control Flow Integri <<
816 depends on ARCH_SUPPORTS_CFI_CLANG <<
817 depends on $(cc-option,-fsanitize=kcfi <<
818 help <<
819 This option enables Clang's forward- <<
820 (CFI) checking, where the compiler i <<
821 indirect function call to ensure the <<
822 the correct static type. This restri <<
823 makes it more difficult for an attac <<
824 the modification of stored function <<
825 found from Clang's documentation: <<
826 <<
827 https://clang.llvm.org/docs/Contro <<
828 <<
829 config CFI_PERMISSIVE <<
830 bool "Use CFI in permissive mode" <<
831 depends on CFI_CLANG <<
832 help <<
833 When selected, Control Flow Integrit <<
834 warning instead of a kernel panic. T <<
835 for finding indirect call type misma <<
836 <<
837 If unsure, say N. <<
838 <<
839 config HAVE_ARCH_WITHIN_STACK_FRAMES 634 config HAVE_ARCH_WITHIN_STACK_FRAMES
840 bool 635 bool
841 help 636 help
842 An architecture should select this i 637 An architecture should select this if it can walk the kernel stack
843 frames to determine if an object is 638 frames to determine if an object is part of either the arguments
844 or local variables (i.e. that it exc 639 or local variables (i.e. that it excludes saved return addresses,
845 and similar) by implementing an inli 640 and similar) by implementing an inline arch_within_stack_frames(),
846 which is used by CONFIG_HARDENED_USE 641 which is used by CONFIG_HARDENED_USERCOPY.
847 642
848 config HAVE_CONTEXT_TRACKING_USER !! 643 config HAVE_CONTEXT_TRACKING
849 bool 644 bool
850 help 645 help
851 Provide kernel/user boundaries probe 646 Provide kernel/user boundaries probes necessary for subsystems
852 that need it, such as userspace RCU 647 that need it, such as userspace RCU extended quiescent state.
853 Syscalls need to be wrapped inside u 648 Syscalls need to be wrapped inside user_exit()-user_enter(), either
854 optimized behind static key or throu 649 optimized behind static key or through the slow path using TIF_NOHZ
855 flag. Exceptions handlers must be wr 650 flag. Exceptions handlers must be wrapped as well. Irqs are already
856 protected inside ct_irq_enter/ct_irq !! 651 protected inside rcu_irq_enter/rcu_irq_exit() but preemption or signal
857 handling on irq exit still need to b 652 handling on irq exit still need to be protected.
858 653
859 config HAVE_CONTEXT_TRACKING_USER_OFFSTACK !! 654 config HAVE_CONTEXT_TRACKING_OFFSTACK
860 bool 655 bool
861 help 656 help
862 Architecture neither relies on excep 657 Architecture neither relies on exception_enter()/exception_exit()
863 nor on schedule_user(). Also preempt 658 nor on schedule_user(). Also preempt_schedule_notrace() and
864 preempt_schedule_irq() can't be call 659 preempt_schedule_irq() can't be called in a preemptible section
865 while context tracking is CONTEXT_US 660 while context tracking is CONTEXT_USER. This feature reflects a sane
866 entry implementation where the follo 661 entry implementation where the following requirements are met on
867 critical entry code, ie: before user 662 critical entry code, ie: before user_exit() or after user_enter():
868 663
869 - Critical entry code isn't preempti 664 - Critical entry code isn't preemptible (or better yet:
870 not interruptible). 665 not interruptible).
871 - No use of RCU read side critical s !! 666 - No use of RCU read side critical sections, unless rcu_nmi_enter()
872 got called. 667 got called.
873 - No use of instrumentation, unless 668 - No use of instrumentation, unless instrumentation_begin() got
874 called. 669 called.
875 670
876 config HAVE_TIF_NOHZ 671 config HAVE_TIF_NOHZ
877 bool 672 bool
878 help 673 help
879 Arch relies on TIF_NOHZ and syscall 674 Arch relies on TIF_NOHZ and syscall slow path to implement context
880 tracking calls to user_enter()/user_ 675 tracking calls to user_enter()/user_exit().
881 676
882 config HAVE_VIRT_CPU_ACCOUNTING 677 config HAVE_VIRT_CPU_ACCOUNTING
883 bool 678 bool
884 679
885 config HAVE_VIRT_CPU_ACCOUNTING_IDLE 680 config HAVE_VIRT_CPU_ACCOUNTING_IDLE
886 bool 681 bool
887 help 682 help
888 Architecture has its own way to acco 683 Architecture has its own way to account idle CPU time and therefore
889 doesn't implement vtime_account_idle 684 doesn't implement vtime_account_idle().
890 685
891 config ARCH_HAS_SCALED_CPUTIME 686 config ARCH_HAS_SCALED_CPUTIME
892 bool 687 bool
893 688
894 config HAVE_VIRT_CPU_ACCOUNTING_GEN 689 config HAVE_VIRT_CPU_ACCOUNTING_GEN
895 bool 690 bool
896 default y if 64BIT 691 default y if 64BIT
897 help 692 help
898 With VIRT_CPU_ACCOUNTING_GEN, cputim 693 With VIRT_CPU_ACCOUNTING_GEN, cputime_t becomes 64-bit.
899 Before enabling this option, arch co 694 Before enabling this option, arch code must be audited
900 to ensure there are no races in conc 695 to ensure there are no races in concurrent read/write of
901 cputime_t. For example, reading/writ 696 cputime_t. For example, reading/writing 64-bit cputime_t on
902 some 32-bit arches may require multi 697 some 32-bit arches may require multiple accesses, so proper
903 locking is needed to protect against 698 locking is needed to protect against concurrent accesses.
904 699
905 config HAVE_IRQ_TIME_ACCOUNTING 700 config HAVE_IRQ_TIME_ACCOUNTING
906 bool 701 bool
907 help 702 help
908 Archs need to ensure they use a high 703 Archs need to ensure they use a high enough resolution clock to
909 support irq time accounting and then 704 support irq time accounting and then call enable_sched_clock_irqtime().
910 705
911 config HAVE_MOVE_PUD 706 config HAVE_MOVE_PUD
912 bool 707 bool
913 help 708 help
914 Architectures that select this are a 709 Architectures that select this are able to move page tables at the
915 PUD level. If there are only 3 page 710 PUD level. If there are only 3 page table levels, the move effectively
916 happens at the PGD level. 711 happens at the PGD level.
917 712
918 config HAVE_MOVE_PMD 713 config HAVE_MOVE_PMD
919 bool 714 bool
920 help 715 help
921 Archs that select this are able to m 716 Archs that select this are able to move page tables at the PMD level.
922 717
923 config HAVE_ARCH_TRANSPARENT_HUGEPAGE 718 config HAVE_ARCH_TRANSPARENT_HUGEPAGE
924 bool 719 bool
925 720
926 config HAVE_ARCH_TRANSPARENT_HUGEPAGE_PUD 721 config HAVE_ARCH_TRANSPARENT_HUGEPAGE_PUD
927 bool 722 bool
928 723
929 config HAVE_ARCH_HUGE_VMAP 724 config HAVE_ARCH_HUGE_VMAP
930 bool 725 bool
931 726
932 # <<
933 # Archs that select this would be capable of <<
934 # arch_vmap_pmd_supported() returns true). Th <<
935 # must be used to enable allocations to use h <<
936 # <<
937 config HAVE_ARCH_HUGE_VMALLOC <<
938 depends on HAVE_ARCH_HUGE_VMAP <<
939 bool <<
940 <<
941 config ARCH_WANT_HUGE_PMD_SHARE 727 config ARCH_WANT_HUGE_PMD_SHARE
942 bool 728 bool
943 729
944 # Archs that want to use pmd_mkwrite on kernel <<
945 # if there are no userspace memory management <<
946 config ARCH_WANT_KERNEL_PMD_MKWRITE <<
947 bool <<
948 <<
949 config ARCH_WANT_PMD_MKWRITE <<
950 def_bool TRANSPARENT_HUGEPAGE || ARCH_ <<
951 <<
952 config HAVE_ARCH_SOFT_DIRTY 730 config HAVE_ARCH_SOFT_DIRTY
953 bool 731 bool
954 732
955 config HAVE_MOD_ARCH_SPECIFIC 733 config HAVE_MOD_ARCH_SPECIFIC
956 bool 734 bool
957 help 735 help
958 The arch uses struct mod_arch_specif 736 The arch uses struct mod_arch_specific to store data. Many arches
959 just need a simple module loader wit 737 just need a simple module loader without arch specific data - those
960 should not enable this. 738 should not enable this.
961 739
962 config MODULES_USE_ELF_RELA 740 config MODULES_USE_ELF_RELA
963 bool 741 bool
964 help 742 help
965 Modules only use ELF RELA relocation 743 Modules only use ELF RELA relocations. Modules with ELF REL
966 relocations will give an error. 744 relocations will give an error.
967 745
968 config MODULES_USE_ELF_REL 746 config MODULES_USE_ELF_REL
969 bool 747 bool
970 help 748 help
971 Modules only use ELF REL relocations 749 Modules only use ELF REL relocations. Modules with ELF RELA
972 relocations will give an error. 750 relocations will give an error.
973 751
974 config ARCH_WANTS_MODULES_DATA_IN_VMALLOC <<
975 bool <<
976 help <<
977 For architectures like powerpc/32 wh <<
978 allocation and need to allocate modu <<
979 <<
980 config ARCH_WANTS_EXECMEM_LATE <<
981 bool <<
982 help <<
983 For architectures that do not alloca <<
984 boot, but rather require its initial <<
985 enough entropy for module space rand <<
986 arm64. <<
987 <<
988 config HAVE_IRQ_EXIT_ON_IRQ_STACK 752 config HAVE_IRQ_EXIT_ON_IRQ_STACK
989 bool 753 bool
990 help 754 help
991 Architecture doesn't only execute th 755 Architecture doesn't only execute the irq handler on the irq stack
992 but also irq_exit(). This way we can 756 but also irq_exit(). This way we can process softirqs on this irq
993 stack instead of switching to a new 757 stack instead of switching to a new one when we call __do_softirq()
994 in the end of an hardirq. 758 in the end of an hardirq.
995 This spares a stack switch and impro 759 This spares a stack switch and improves cache usage on softirq
996 processing. 760 processing.
997 761
998 config HAVE_SOFTIRQ_ON_OWN_STACK <<
999 bool <<
1000 help <<
1001 Architecture provides a function to <<
1002 separate stack. <<
1003 <<
1004 config SOFTIRQ_ON_OWN_STACK <<
1005 def_bool HAVE_SOFTIRQ_ON_OWN_STACK && <<
1006 <<
1007 config ALTERNATE_USER_ADDRESS_SPACE <<
1008 bool <<
1009 help <<
1010 Architectures set this when the CPU <<
1011 spaces for kernel and user space po <<
1012 access_ok() check on a __user point <<
1013 <<
1014 config PGTABLE_LEVELS 762 config PGTABLE_LEVELS
1015 int 763 int
1016 default 2 764 default 2
1017 765
1018 config ARCH_HAS_ELF_RANDOMIZE 766 config ARCH_HAS_ELF_RANDOMIZE
1019 bool 767 bool
1020 help 768 help
1021 An architecture supports choosing r 769 An architecture supports choosing randomized locations for
1022 stack, mmap, brk, and ET_DYN. Defin 770 stack, mmap, brk, and ET_DYN. Defined functions:
1023 - arch_mmap_rnd() 771 - arch_mmap_rnd()
1024 - arch_randomize_brk() 772 - arch_randomize_brk()
1025 773
1026 config HAVE_ARCH_MMAP_RND_BITS 774 config HAVE_ARCH_MMAP_RND_BITS
1027 bool 775 bool
1028 help 776 help
1029 An arch should select this symbol i 777 An arch should select this symbol if it supports setting a variable
1030 number of bits for use in establish 778 number of bits for use in establishing the base address for mmap
1031 allocations, has MMU enabled and pr 779 allocations, has MMU enabled and provides values for both:
1032 - ARCH_MMAP_RND_BITS_MIN 780 - ARCH_MMAP_RND_BITS_MIN
1033 - ARCH_MMAP_RND_BITS_MAX 781 - ARCH_MMAP_RND_BITS_MAX
1034 782
1035 config HAVE_EXIT_THREAD 783 config HAVE_EXIT_THREAD
1036 bool 784 bool
1037 help 785 help
1038 An architecture implements exit_thr 786 An architecture implements exit_thread.
1039 787
1040 config ARCH_MMAP_RND_BITS_MIN 788 config ARCH_MMAP_RND_BITS_MIN
1041 int 789 int
1042 790
1043 config ARCH_MMAP_RND_BITS_MAX 791 config ARCH_MMAP_RND_BITS_MAX
1044 int 792 int
1045 793
1046 config ARCH_MMAP_RND_BITS_DEFAULT 794 config ARCH_MMAP_RND_BITS_DEFAULT
1047 int 795 int
1048 796
1049 config ARCH_MMAP_RND_BITS 797 config ARCH_MMAP_RND_BITS
1050 int "Number of bits to use for ASLR o 798 int "Number of bits to use for ASLR of mmap base address" if EXPERT
1051 range ARCH_MMAP_RND_BITS_MIN ARCH_MMA 799 range ARCH_MMAP_RND_BITS_MIN ARCH_MMAP_RND_BITS_MAX
1052 default ARCH_MMAP_RND_BITS_DEFAULT if 800 default ARCH_MMAP_RND_BITS_DEFAULT if ARCH_MMAP_RND_BITS_DEFAULT
1053 default ARCH_MMAP_RND_BITS_MIN 801 default ARCH_MMAP_RND_BITS_MIN
1054 depends on HAVE_ARCH_MMAP_RND_BITS 802 depends on HAVE_ARCH_MMAP_RND_BITS
1055 help 803 help
1056 This value can be used to select th 804 This value can be used to select the number of bits to use to
1057 determine the random offset to the 805 determine the random offset to the base address of vma regions
1058 resulting from mmap allocations. Th 806 resulting from mmap allocations. This value will be bounded
1059 by the architecture's minimum and m 807 by the architecture's minimum and maximum supported values.
1060 808
1061 This value can be changed after boo 809 This value can be changed after boot using the
1062 /proc/sys/vm/mmap_rnd_bits tunable 810 /proc/sys/vm/mmap_rnd_bits tunable
1063 811
1064 config HAVE_ARCH_MMAP_RND_COMPAT_BITS 812 config HAVE_ARCH_MMAP_RND_COMPAT_BITS
1065 bool 813 bool
1066 help 814 help
1067 An arch should select this symbol i 815 An arch should select this symbol if it supports running applications
1068 in compatibility mode, supports set 816 in compatibility mode, supports setting a variable number of bits for
1069 use in establishing the base addres 817 use in establishing the base address for mmap allocations, has MMU
1070 enabled and provides values for bot 818 enabled and provides values for both:
1071 - ARCH_MMAP_RND_COMPAT_BITS_MIN 819 - ARCH_MMAP_RND_COMPAT_BITS_MIN
1072 - ARCH_MMAP_RND_COMPAT_BITS_MAX 820 - ARCH_MMAP_RND_COMPAT_BITS_MAX
1073 821
1074 config ARCH_MMAP_RND_COMPAT_BITS_MIN 822 config ARCH_MMAP_RND_COMPAT_BITS_MIN
1075 int 823 int
1076 824
1077 config ARCH_MMAP_RND_COMPAT_BITS_MAX 825 config ARCH_MMAP_RND_COMPAT_BITS_MAX
1078 int 826 int
1079 827
1080 config ARCH_MMAP_RND_COMPAT_BITS_DEFAULT 828 config ARCH_MMAP_RND_COMPAT_BITS_DEFAULT
1081 int 829 int
1082 830
1083 config ARCH_MMAP_RND_COMPAT_BITS 831 config ARCH_MMAP_RND_COMPAT_BITS
1084 int "Number of bits to use for ASLR o 832 int "Number of bits to use for ASLR of mmap base address for compatible applications" if EXPERT
1085 range ARCH_MMAP_RND_COMPAT_BITS_MIN A 833 range ARCH_MMAP_RND_COMPAT_BITS_MIN ARCH_MMAP_RND_COMPAT_BITS_MAX
1086 default ARCH_MMAP_RND_COMPAT_BITS_DEF 834 default ARCH_MMAP_RND_COMPAT_BITS_DEFAULT if ARCH_MMAP_RND_COMPAT_BITS_DEFAULT
1087 default ARCH_MMAP_RND_COMPAT_BITS_MIN 835 default ARCH_MMAP_RND_COMPAT_BITS_MIN
1088 depends on HAVE_ARCH_MMAP_RND_COMPAT_ 836 depends on HAVE_ARCH_MMAP_RND_COMPAT_BITS
1089 help 837 help
1090 This value can be used to select th 838 This value can be used to select the number of bits to use to
1091 determine the random offset to the 839 determine the random offset to the base address of vma regions
1092 resulting from mmap allocations for 840 resulting from mmap allocations for compatible applications This
1093 value will be bounded by the archit 841 value will be bounded by the architecture's minimum and maximum
1094 supported values. 842 supported values.
1095 843
1096 This value can be changed after boo 844 This value can be changed after boot using the
1097 /proc/sys/vm/mmap_rnd_compat_bits t 845 /proc/sys/vm/mmap_rnd_compat_bits tunable
1098 846
1099 config HAVE_ARCH_COMPAT_MMAP_BASES 847 config HAVE_ARCH_COMPAT_MMAP_BASES
1100 bool 848 bool
1101 help 849 help
1102 This allows 64bit applications to i 850 This allows 64bit applications to invoke 32-bit mmap() syscall
1103 and vice-versa 32-bit applications 851 and vice-versa 32-bit applications to call 64-bit mmap().
1104 Required for applications doing dif 852 Required for applications doing different bitness syscalls.
1105 853
1106 config HAVE_PAGE_SIZE_4KB <<
1107 bool <<
1108 <<
1109 config HAVE_PAGE_SIZE_8KB <<
1110 bool <<
1111 <<
1112 config HAVE_PAGE_SIZE_16KB <<
1113 bool <<
1114 <<
1115 config HAVE_PAGE_SIZE_32KB <<
1116 bool <<
1117 <<
1118 config HAVE_PAGE_SIZE_64KB <<
1119 bool <<
1120 <<
1121 config HAVE_PAGE_SIZE_256KB <<
1122 bool <<
1123 <<
1124 choice <<
1125 prompt "MMU page size" <<
1126 <<
1127 config PAGE_SIZE_4KB <<
1128 bool "4KiB pages" <<
1129 depends on HAVE_PAGE_SIZE_4KB <<
1130 help <<
1131 This option select the standard 4Ki <<
1132 available option on many architectu <<
1133 minimize memory consumption and is <<
1134 memory systems. <<
1135 Some software that is written for x <<
1136 assumptions about the page size and <<
1137 <<
1138 config PAGE_SIZE_8KB <<
1139 bool "8KiB pages" <<
1140 depends on HAVE_PAGE_SIZE_8KB <<
1141 help <<
1142 This option is the only supported p <<
1143 processors, and can be slightly fas <<
1144 <<
1145 config PAGE_SIZE_16KB <<
1146 bool "16KiB pages" <<
1147 depends on HAVE_PAGE_SIZE_16KB <<
1148 help <<
1149 This option is usually a good compr <<
1150 consumption and performance for typ <<
1151 workloads, often saving a level of <<
1152 to 4KB pages as well as reducing TL <<
1153 per-page operations in the kernel a <<
1154 page cache. <<
1155 <<
1156 config PAGE_SIZE_32KB <<
1157 bool "32KiB pages" <<
1158 depends on HAVE_PAGE_SIZE_32KB <<
1159 help <<
1160 Using 32KiB page size will result i <<
1161 kernel at the price of higher memor <<
1162 16KiB pages. This option is availa <<
1163 Note that you will need a suitable <<
1164 support this. <<
1165 <<
1166 config PAGE_SIZE_64KB <<
1167 bool "64KiB pages" <<
1168 depends on HAVE_PAGE_SIZE_64KB <<
1169 help <<
1170 Using 64KiB page size will result i <<
1171 kernel at the price of much higher <<
1172 4KiB or 16KiB pages. <<
1173 This is not suitable for general-pu <<
1174 better performance may be worth the <<
1175 supercomputing or database applicat <<
1176 large in-memory data rather than sm <<
1177 <<
1178 config PAGE_SIZE_256KB <<
1179 bool "256KiB pages" <<
1180 depends on HAVE_PAGE_SIZE_256KB <<
1181 help <<
1182 256KiB pages have little practical <<
1183 memory usage. The kernel will only <<
1184 that have been compiled with '-zmax <<
1185 (the default is 64KiB or 4KiB on mo <<
1186 <<
1187 endchoice <<
1188 <<
1189 config PAGE_SIZE_LESS_THAN_64KB <<
1190 def_bool y <<
1191 depends on !PAGE_SIZE_64KB <<
1192 depends on PAGE_SIZE_LESS_THAN_256KB <<
1193 <<
1194 config PAGE_SIZE_LESS_THAN_256KB <<
1195 def_bool y <<
1196 depends on !PAGE_SIZE_256KB <<
1197 <<
1198 config PAGE_SHIFT <<
1199 int <<
1200 default 12 if PAGE_SIZE_4KB <<
1201 default 13 if PAGE_SIZE_8KB <<
1202 default 14 if PAGE_SIZE_16KB <<
1203 default 15 if PAGE_SIZE_32KB <<
1204 default 16 if PAGE_SIZE_64KB <<
1205 default 18 if PAGE_SIZE_256KB <<
1206 <<
1207 # This allows to use a set of generic functio 854 # This allows to use a set of generic functions to determine mmap base
1208 # address by giving priority to top-down sche 855 # address by giving priority to top-down scheme only if the process
1209 # is not in legacy mode (compat task, unlimit 856 # is not in legacy mode (compat task, unlimited stack size or
1210 # sysctl_legacy_va_layout). 857 # sysctl_legacy_va_layout).
1211 # Architecture that selects this option can p 858 # Architecture that selects this option can provide its own version of:
1212 # - STACK_RND_MASK 859 # - STACK_RND_MASK
1213 config ARCH_WANT_DEFAULT_TOPDOWN_MMAP_LAYOUT 860 config ARCH_WANT_DEFAULT_TOPDOWN_MMAP_LAYOUT
1214 bool 861 bool
1215 depends on MMU 862 depends on MMU
1216 select ARCH_HAS_ELF_RANDOMIZE 863 select ARCH_HAS_ELF_RANDOMIZE
1217 864
1218 config HAVE_OBJTOOL <<
1219 bool <<
1220 <<
1221 config HAVE_JUMP_LABEL_HACK <<
1222 bool <<
1223 <<
1224 config HAVE_NOINSTR_HACK <<
1225 bool <<
1226 <<
1227 config HAVE_NOINSTR_VALIDATION <<
1228 bool <<
1229 <<
1230 config HAVE_UACCESS_VALIDATION <<
1231 bool <<
1232 select OBJTOOL <<
1233 <<
1234 config HAVE_STACK_VALIDATION 865 config HAVE_STACK_VALIDATION
1235 bool 866 bool
1236 help 867 help
1237 Architecture supports objtool compi !! 868 Architecture supports the 'objtool check' host tool command, which
1238 validation. !! 869 performs compile-time stack metadata validation.
1239 870
1240 config HAVE_RELIABLE_STACKTRACE 871 config HAVE_RELIABLE_STACKTRACE
1241 bool 872 bool
1242 help 873 help
1243 Architecture has either save_stack_ 874 Architecture has either save_stack_trace_tsk_reliable() or
1244 arch_stack_walk_reliable() function 875 arch_stack_walk_reliable() function which only returns a stack trace
1245 if it can guarantee the trace is re 876 if it can guarantee the trace is reliable.
1246 877
1247 config HAVE_ARCH_HASH 878 config HAVE_ARCH_HASH
1248 bool 879 bool
1249 default n 880 default n
1250 help 881 help
1251 If this is set, the architecture pr 882 If this is set, the architecture provides an <asm/hash.h>
1252 file which provides platform-specif 883 file which provides platform-specific implementations of some
1253 functions in <linux/hash.h> or fs/n 884 functions in <linux/hash.h> or fs/namei.c.
1254 885
1255 config HAVE_ARCH_NVRAM_OPS 886 config HAVE_ARCH_NVRAM_OPS
1256 bool 887 bool
1257 888
1258 config ISA_BUS_API 889 config ISA_BUS_API
1259 def_bool ISA 890 def_bool ISA
1260 891
1261 # 892 #
1262 # ABI hall of shame 893 # ABI hall of shame
1263 # 894 #
1264 config CLONE_BACKWARDS 895 config CLONE_BACKWARDS
1265 bool 896 bool
1266 help 897 help
1267 Architecture has tls passed as the 898 Architecture has tls passed as the 4th argument of clone(2),
1268 not the 5th one. 899 not the 5th one.
1269 900
1270 config CLONE_BACKWARDS2 901 config CLONE_BACKWARDS2
1271 bool 902 bool
1272 help 903 help
1273 Architecture has the first two argu 904 Architecture has the first two arguments of clone(2) swapped.
1274 905
1275 config CLONE_BACKWARDS3 906 config CLONE_BACKWARDS3
1276 bool 907 bool
1277 help 908 help
1278 Architecture has tls passed as the 909 Architecture has tls passed as the 3rd argument of clone(2),
1279 not the 5th one. 910 not the 5th one.
1280 911
1281 config ODD_RT_SIGACTION 912 config ODD_RT_SIGACTION
1282 bool 913 bool
1283 help 914 help
1284 Architecture has unusual rt_sigacti 915 Architecture has unusual rt_sigaction(2) arguments
1285 916
1286 config OLD_SIGSUSPEND 917 config OLD_SIGSUSPEND
1287 bool 918 bool
1288 help 919 help
1289 Architecture has old sigsuspend(2) 920 Architecture has old sigsuspend(2) syscall, of one-argument variety
1290 921
1291 config OLD_SIGSUSPEND3 922 config OLD_SIGSUSPEND3
1292 bool 923 bool
1293 help 924 help
1294 Even weirder antique ABI - three-ar 925 Even weirder antique ABI - three-argument sigsuspend(2)
1295 926
1296 config OLD_SIGACTION 927 config OLD_SIGACTION
1297 bool 928 bool
1298 help 929 help
1299 Architecture has old sigaction(2) s 930 Architecture has old sigaction(2) syscall. Nope, not the same
1300 as OLD_SIGSUSPEND | OLD_SIGSUSPEND3 931 as OLD_SIGSUSPEND | OLD_SIGSUSPEND3 - alpha has sigsuspend(2),
1301 but fairly different variant of sig 932 but fairly different variant of sigaction(2), thanks to OSF/1
1302 compatibility... 933 compatibility...
1303 934
1304 config COMPAT_OLD_SIGACTION 935 config COMPAT_OLD_SIGACTION
1305 bool 936 bool
1306 937
1307 config COMPAT_32BIT_TIME 938 config COMPAT_32BIT_TIME
1308 bool "Provide system calls for 32-bit 939 bool "Provide system calls for 32-bit time_t"
1309 default !64BIT || COMPAT 940 default !64BIT || COMPAT
1310 help 941 help
1311 This enables 32 bit time_t support 942 This enables 32 bit time_t support in addition to 64 bit time_t support.
1312 This is relevant on all 32-bit arch 943 This is relevant on all 32-bit architectures, and 64-bit architectures
1313 as part of compat syscall handling. 944 as part of compat syscall handling.
1314 945
1315 config ARCH_NO_PREEMPT 946 config ARCH_NO_PREEMPT
1316 bool 947 bool
1317 948
1318 config ARCH_SUPPORTS_RT 949 config ARCH_SUPPORTS_RT
1319 bool 950 bool
1320 951
1321 config CPU_NO_EFFICIENT_FFS 952 config CPU_NO_EFFICIENT_FFS
1322 def_bool n 953 def_bool n
1323 954
1324 config HAVE_ARCH_VMAP_STACK 955 config HAVE_ARCH_VMAP_STACK
1325 def_bool n 956 def_bool n
1326 help 957 help
1327 An arch should select this symbol i 958 An arch should select this symbol if it can support kernel stacks
1328 in vmalloc space. This means: 959 in vmalloc space. This means:
1329 960
1330 - vmalloc space must be large enoug 961 - vmalloc space must be large enough to hold many kernel stacks.
1331 This may rule out many 32-bit arc 962 This may rule out many 32-bit architectures.
1332 963
1333 - Stacks in vmalloc space need to w 964 - Stacks in vmalloc space need to work reliably. For example, if
1334 vmap page tables are created on d 965 vmap page tables are created on demand, either this mechanism
1335 needs to work while the stack poi 966 needs to work while the stack points to a virtual address with
1336 unpopulated page tables or arch c 967 unpopulated page tables or arch code (switch_to() and switch_mm(),
1337 most likely) needs to ensure that 968 most likely) needs to ensure that the stack's page table entries
1338 are populated before running on a 969 are populated before running on a possibly unpopulated stack.
1339 970
1340 - If the stack overflows into a gua 971 - If the stack overflows into a guard page, something reasonable
1341 should happen. The definition of 972 should happen. The definition of "reasonable" is flexible, but
1342 instantly rebooting without loggi 973 instantly rebooting without logging anything would be unfriendly.
1343 974
1344 config VMAP_STACK 975 config VMAP_STACK
1345 default y 976 default y
1346 bool "Use a virtually-mapped stack" 977 bool "Use a virtually-mapped stack"
1347 depends on HAVE_ARCH_VMAP_STACK 978 depends on HAVE_ARCH_VMAP_STACK
1348 depends on !KASAN || KASAN_HW_TAGS || 979 depends on !KASAN || KASAN_HW_TAGS || KASAN_VMALLOC
1349 help 980 help
1350 Enable this if you want the use vir 981 Enable this if you want the use virtually-mapped kernel stacks
1351 with guard pages. This causes kern 982 with guard pages. This causes kernel stack overflows to be
1352 caught immediately rather than caus 983 caught immediately rather than causing difficult-to-diagnose
1353 corruption. 984 corruption.
1354 985
1355 To use this with software KASAN mod 986 To use this with software KASAN modes, the architecture must support
1356 backing virtual mappings with real 987 backing virtual mappings with real shadow memory, and KASAN_VMALLOC
1357 must be enabled. 988 must be enabled.
1358 989
1359 config HAVE_ARCH_RANDOMIZE_KSTACK_OFFSET <<
1360 def_bool n <<
1361 help <<
1362 An arch should select this symbol i <<
1363 offset randomization with calls to <<
1364 during syscall entry and choose_ran <<
1365 syscall exit. Careful removal of -f <<
1366 -fstack-protector should also be ap <<
1367 closely examined, as the artificial <<
1368 to the compiler, so it will attempt <<
1369 of the static branch state. <<
1370 <<
1371 config RANDOMIZE_KSTACK_OFFSET <<
1372 bool "Support for randomizing kernel <<
1373 default y <<
1374 depends on HAVE_ARCH_RANDOMIZE_KSTACK <<
1375 depends on INIT_STACK_NONE || !CC_IS_ <<
1376 help <<
1377 The kernel stack offset can be rand <<
1378 roughly 5 bits of entropy, frustrat <<
1379 attacks that depend on stack addres <<
1380 cross-syscall address exposures. <<
1381 <<
1382 The feature is controlled via the " <<
1383 kernel boot param, and if turned of <<
1384 of static branches (see JUMP_LABEL) <<
1385 <<
1386 If unsure, say Y. <<
1387 <<
1388 config RANDOMIZE_KSTACK_OFFSET_DEFAULT <<
1389 bool "Default state of kernel stack o <<
1390 depends on RANDOMIZE_KSTACK_OFFSET <<
1391 help <<
1392 Kernel stack offset randomization i <<
1393 "randomize_kstack_offset=on/off", a <<
1394 boot state. <<
1395 <<
1396 config ARCH_OPTIONAL_KERNEL_RWX 990 config ARCH_OPTIONAL_KERNEL_RWX
1397 def_bool n 991 def_bool n
1398 992
1399 config ARCH_OPTIONAL_KERNEL_RWX_DEFAULT 993 config ARCH_OPTIONAL_KERNEL_RWX_DEFAULT
1400 def_bool n 994 def_bool n
1401 995
1402 config ARCH_HAS_STRICT_KERNEL_RWX 996 config ARCH_HAS_STRICT_KERNEL_RWX
1403 def_bool n 997 def_bool n
1404 998
1405 config STRICT_KERNEL_RWX 999 config STRICT_KERNEL_RWX
1406 bool "Make kernel text and rodata rea 1000 bool "Make kernel text and rodata read-only" if ARCH_OPTIONAL_KERNEL_RWX
1407 depends on ARCH_HAS_STRICT_KERNEL_RWX 1001 depends on ARCH_HAS_STRICT_KERNEL_RWX
1408 default !ARCH_OPTIONAL_KERNEL_RWX || 1002 default !ARCH_OPTIONAL_KERNEL_RWX || ARCH_OPTIONAL_KERNEL_RWX_DEFAULT
1409 help 1003 help
1410 If this is set, kernel text and rod 1004 If this is set, kernel text and rodata memory will be made read-only,
1411 and non-text memory will be made no 1005 and non-text memory will be made non-executable. This provides
1412 protection against certain security 1006 protection against certain security exploits (e.g. executing the heap
1413 or modifying text) 1007 or modifying text)
1414 1008
1415 These features are considered stand 1009 These features are considered standard security practice these days.
1416 You should say Y here in almost all 1010 You should say Y here in almost all cases.
1417 1011
1418 config ARCH_HAS_STRICT_MODULE_RWX 1012 config ARCH_HAS_STRICT_MODULE_RWX
1419 def_bool n 1013 def_bool n
1420 1014
1421 config STRICT_MODULE_RWX 1015 config STRICT_MODULE_RWX
1422 bool "Set loadable kernel module data 1016 bool "Set loadable kernel module data as NX and text as RO" if ARCH_OPTIONAL_KERNEL_RWX
1423 depends on ARCH_HAS_STRICT_MODULE_RWX 1017 depends on ARCH_HAS_STRICT_MODULE_RWX && MODULES
1424 default !ARCH_OPTIONAL_KERNEL_RWX || 1018 default !ARCH_OPTIONAL_KERNEL_RWX || ARCH_OPTIONAL_KERNEL_RWX_DEFAULT
1425 help 1019 help
1426 If this is set, module text and rod 1020 If this is set, module text and rodata memory will be made read-only,
1427 and non-text memory will be made no 1021 and non-text memory will be made non-executable. This provides
1428 protection against certain security 1022 protection against certain security exploits (e.g. writing to text)
1429 1023
1430 # select if the architecture provides an asm/ 1024 # select if the architecture provides an asm/dma-direct.h header
1431 config ARCH_HAS_PHYS_TO_DMA 1025 config ARCH_HAS_PHYS_TO_DMA
1432 bool 1026 bool
1433 1027
1434 config HAVE_ARCH_COMPILER_H 1028 config HAVE_ARCH_COMPILER_H
1435 bool 1029 bool
1436 help 1030 help
1437 An architecture can select this if 1031 An architecture can select this if it provides an
1438 asm/compiler.h header that should b 1032 asm/compiler.h header that should be included after
1439 linux/compiler-*.h in order to over 1033 linux/compiler-*.h in order to override macro definitions that those
1440 headers generally provide. 1034 headers generally provide.
1441 1035
1442 config HAVE_ARCH_PREL32_RELOCATIONS 1036 config HAVE_ARCH_PREL32_RELOCATIONS
1443 bool 1037 bool
1444 help 1038 help
1445 May be selected by an architecture 1039 May be selected by an architecture if it supports place-relative
1446 32-bit relocations, both in the too 1040 32-bit relocations, both in the toolchain and in the module loader,
1447 in which case relative references c 1041 in which case relative references can be used in special sections
1448 for PCI fixup, initcalls etc which 1042 for PCI fixup, initcalls etc which are only half the size on 64 bit
1449 architectures, and don't require ru 1043 architectures, and don't require runtime relocation on relocatable
1450 kernels. 1044 kernels.
1451 1045
1452 config ARCH_USE_MEMREMAP_PROT 1046 config ARCH_USE_MEMREMAP_PROT
1453 bool 1047 bool
1454 1048
1455 config LOCK_EVENT_COUNTS 1049 config LOCK_EVENT_COUNTS
1456 bool "Locking event counts collection 1050 bool "Locking event counts collection"
1457 depends on DEBUG_FS 1051 depends on DEBUG_FS
1458 help 1052 help
1459 Enable light-weight counting of var 1053 Enable light-weight counting of various locking related events
1460 in the system with minimal performa 1054 in the system with minimal performance impact. This reduces
1461 the chance of application behavior 1055 the chance of application behavior change because of timing
1462 differences. The counts are reporte 1056 differences. The counts are reported via debugfs.
1463 1057
1464 # Select if the architecture has support for 1058 # Select if the architecture has support for applying RELR relocations.
1465 config ARCH_HAS_RELR 1059 config ARCH_HAS_RELR
1466 bool 1060 bool
1467 1061
1468 config RELR 1062 config RELR
1469 bool "Use RELR relocation packing" 1063 bool "Use RELR relocation packing"
1470 depends on ARCH_HAS_RELR && TOOLS_SUP 1064 depends on ARCH_HAS_RELR && TOOLS_SUPPORT_RELR
1471 default y 1065 default y
1472 help 1066 help
1473 Store the kernel's dynamic relocati 1067 Store the kernel's dynamic relocations in the RELR relocation packing
1474 format. Requires a compatible linke 1068 format. Requires a compatible linker (LLD supports this feature), as
1475 well as compatible NM and OBJCOPY u 1069 well as compatible NM and OBJCOPY utilities (llvm-nm and llvm-objcopy
1476 are compatible). 1070 are compatible).
1477 1071
1478 config ARCH_HAS_MEM_ENCRYPT 1072 config ARCH_HAS_MEM_ENCRYPT
1479 bool 1073 bool
1480 1074
1481 config ARCH_HAS_CC_PLATFORM <<
1482 bool <<
1483 <<
1484 config HAVE_SPARSE_SYSCALL_NR 1075 config HAVE_SPARSE_SYSCALL_NR
1485 bool !! 1076 bool
1486 help !! 1077 help
1487 An architecture should select this !! 1078 An architecture should select this if its syscall numbering is sparse
1488 to save space. For example, MIPS ar 1079 to save space. For example, MIPS architecture has a syscall array with
1489 entries at 4000, 5000 and 6000 loca 1080 entries at 4000, 5000 and 6000 locations. This option turns on syscall
1490 related optimizations for a given a 1081 related optimizations for a given architecture.
1491 1082
1492 config ARCH_HAS_VDSO_DATA 1083 config ARCH_HAS_VDSO_DATA
1493 bool 1084 bool
1494 1085
1495 config HAVE_STATIC_CALL 1086 config HAVE_STATIC_CALL
1496 bool 1087 bool
1497 1088
1498 config HAVE_STATIC_CALL_INLINE 1089 config HAVE_STATIC_CALL_INLINE
1499 bool 1090 bool
1500 depends on HAVE_STATIC_CALL 1091 depends on HAVE_STATIC_CALL
1501 select OBJTOOL <<
1502 <<
1503 config HAVE_PREEMPT_DYNAMIC <<
1504 bool <<
1505 <<
1506 config HAVE_PREEMPT_DYNAMIC_CALL <<
1507 bool <<
1508 depends on HAVE_STATIC_CALL <<
1509 select HAVE_PREEMPT_DYNAMIC <<
1510 help <<
1511 An architecture should select this <<
1512 model being selected at boot time u <<
1513 <<
1514 Where an architecture selects HAVE_ <<
1515 preemption function will be patched <<
1516 <<
1517 Where an architecture does not sele <<
1518 call to a preemption function will <<
1519 trampoline will be patched. <<
1520 <<
1521 It is strongly advised to support i <<
1522 overhead. <<
1523 <<
1524 config HAVE_PREEMPT_DYNAMIC_KEY <<
1525 bool <<
1526 depends on HAVE_ARCH_JUMP_LABEL <<
1527 select HAVE_PREEMPT_DYNAMIC <<
1528 help <<
1529 An architecture should select this <<
1530 model being selected at boot time u <<
1531 <<
1532 Each preemption function will be gi <<
1533 static key. This should have slight <<
1534 static calls, as this effectively i <<
1535 start of its callee. This may avoid <<
1536 integrate better with CFI schemes. <<
1537 <<
1538 This will have greater overhead tha <<
1539 the call to the preemption function <<
1540 1092
1541 config ARCH_WANT_LD_ORPHAN_WARN 1093 config ARCH_WANT_LD_ORPHAN_WARN
1542 bool 1094 bool
1543 help 1095 help
1544 An arch should select this symbol o 1096 An arch should select this symbol once all linker sections are explicitly
1545 included, size-asserted, or discard 1097 included, size-asserted, or discarded in the linker scripts. This is
1546 important because we never want exp 1098 important because we never want expected sections to be placed heuristically
1547 by the linker, since the locations 1099 by the linker, since the locations of such sections can change between linker
1548 versions. 1100 versions.
1549 1101
1550 config HAVE_ARCH_PFN_VALID 1102 config HAVE_ARCH_PFN_VALID
1551 bool 1103 bool
1552 1104
1553 config ARCH_SUPPORTS_DEBUG_PAGEALLOC 1105 config ARCH_SUPPORTS_DEBUG_PAGEALLOC
1554 bool 1106 bool
1555 1107
1556 config ARCH_SUPPORTS_PAGE_TABLE_CHECK <<
1557 bool <<
1558 <<
1559 config ARCH_SPLIT_ARG64 1108 config ARCH_SPLIT_ARG64
1560 bool 1109 bool
1561 help 1110 help
1562 If a 32-bit architecture requires 6 !! 1111 If a 32-bit architecture requires 64-bit arguments to be split into
1563 pairs of 32-bit arguments, select t !! 1112 pairs of 32-bit arguments, select this option.
1564 <<
1565 config ARCH_HAS_ELFCORE_COMPAT <<
1566 bool <<
1567 <<
1568 config ARCH_HAS_PARANOID_L1D_FLUSH <<
1569 bool <<
1570 <<
1571 config ARCH_HAVE_TRACE_MMIO_ACCESS <<
1572 bool <<
1573 <<
1574 config DYNAMIC_SIGFRAME <<
1575 bool <<
1576 <<
1577 # Select, if arch has a named attribute group <<
1578 config HAVE_ARCH_NODE_DEV_GROUP <<
1579 bool <<
1580 <<
1581 config ARCH_HAS_HW_PTE_YOUNG <<
1582 bool <<
1583 help <<
1584 Architectures that select this opti <<
1585 accessed bit in PTE entries when us <<
1586 translations. Architectures that re <<
1587 this option and override arch_has_h <<
1588 <<
1589 config ARCH_HAS_NONLEAF_PMD_YOUNG <<
1590 bool <<
1591 help <<
1592 Architectures that select this opti <<
1593 accessed bit in non-leaf PMD entrie <<
1594 address translations. Page table wa <<
1595 may use this capability to reduce t <<
1596 <<
1597 config ARCH_HAS_KERNEL_FPU_SUPPORT <<
1598 bool <<
1599 help <<
1600 Architectures that select this opti <<
1601 the kernel, as described in Documen <<
1602 1113
1603 source "kernel/gcov/Kconfig" 1114 source "kernel/gcov/Kconfig"
1604 1115
1605 source "scripts/gcc-plugins/Kconfig" 1116 source "scripts/gcc-plugins/Kconfig"
1606 <<
1607 config FUNCTION_ALIGNMENT_4B <<
1608 bool <<
1609 <<
1610 config FUNCTION_ALIGNMENT_8B <<
1611 bool <<
1612 <<
1613 config FUNCTION_ALIGNMENT_16B <<
1614 bool <<
1615 <<
1616 config FUNCTION_ALIGNMENT_32B <<
1617 bool <<
1618 <<
1619 config FUNCTION_ALIGNMENT_64B <<
1620 bool <<
1621 <<
1622 config FUNCTION_ALIGNMENT <<
1623 int <<
1624 default 64 if FUNCTION_ALIGNMENT_64B <<
1625 default 32 if FUNCTION_ALIGNMENT_32B <<
1626 default 16 if FUNCTION_ALIGNMENT_16B <<
1627 default 8 if FUNCTION_ALIGNMENT_8B <<
1628 default 4 if FUNCTION_ALIGNMENT_4B <<
1629 default 0 <<
1630 <<
1631 config CC_HAS_MIN_FUNCTION_ALIGNMENT <<
1632 # Detect availability of the GCC opti <<
1633 # guarantees minimal alignment for al <<
1634 # -falign-functions which the compile <<
1635 def_bool $(cc-option, -fmin-function- <<
1636 <<
1637 config CC_HAS_SANE_FUNCTION_ALIGNMENT <<
1638 # Set if the guaranteed alignment wit <<
1639 # available or extra care is required <<
1640 # strict alignment always, even with <<
1641 def_bool CC_HAS_MIN_FUNCTION_ALIGNMEN <<
1642 <<
1643 config ARCH_NEED_CMPXCHG_1_EMU <<
1644 bool <<
1645 1117
1646 endmenu 1118 endmenu
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