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
>> 14 config CRASH_CORE
13 bool 15 bool
14 16
15 if !ARCH_CONFIGURES_CPU_MITIGATIONS !! 17 config KEXEC_CORE
16 config CPU_MITIGATIONS !! 18 select CRASH_CORE
17 def_bool y !! 19 bool
18 endif <<
19 20
20 # !! 21 config KEXEC_ELF
21 # Selected by architectures that need custom D <<
22 # IOMMUs not handled by dma-iommu. Drivers mu <<
23 # <<
24 config ARCH_HAS_DMA_OPS <<
25 depends on HAS_DMA <<
26 select DMA_OPS_HELPERS <<
27 bool 22 bool
28 23
29 menu "General architecture-dependent options" !! 24 config HAVE_IMA_KEXEC
>> 25 bool
30 26
31 config ARCH_HAS_SUBPAGE_FAULTS !! 27 config SET_FS
32 bool 28 bool
33 help <<
34 Select if the architecture can check <<
35 granularity (e.g. arm64 MTE). The pr <<
36 must be implemented. <<
37 29
38 config HOTPLUG_SMT 30 config HOTPLUG_SMT
39 bool 31 bool
40 32
41 config SMT_NUM_THREADS_DYNAMIC !! 33 config GENERIC_ENTRY
42 bool !! 34 bool
43 35
44 # Selected by HOTPLUG_CORE_SYNC_DEAD or HOTPLU !! 36 config OPROFILE
45 config HOTPLUG_CORE_SYNC !! 37 tristate "OProfile system profiling"
46 bool !! 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.
47 46
48 # Basic CPU dead synchronization selected by a !! 47 If unsure, say N.
49 config HOTPLUG_CORE_SYNC_DEAD <<
50 bool <<
51 select HOTPLUG_CORE_SYNC <<
52 48
53 # Full CPU synchronization with alive state se !! 49 config OPROFILE_EVENT_MULTIPLEX
54 config HOTPLUG_CORE_SYNC_FULL !! 50 bool "OProfile multiplexing support (EXPERIMENTAL)"
55 bool !! 51 default n
56 select HOTPLUG_CORE_SYNC_DEAD if HOTPL !! 52 depends on OPROFILE && X86
57 select HOTPLUG_CORE_SYNC !! 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 58
59 config HOTPLUG_SPLIT_STARTUP !! 59 If unsure, say N.
60 bool <<
61 select HOTPLUG_CORE_SYNC_FULL <<
62 60
63 config HOTPLUG_PARALLEL !! 61 config HAVE_OPROFILE
64 bool 62 bool
65 select HOTPLUG_SPLIT_STARTUP <<
66 63
67 config GENERIC_ENTRY !! 64 config OPROFILE_NMI_TIMER
68 bool !! 65 def_bool y
>> 66 depends on PERF_EVENTS && HAVE_PERF_EVENTS_NMI && !PPC64
69 67
70 config KPROBES 68 config KPROBES
71 bool "Kprobes" 69 bool "Kprobes"
>> 70 depends on MODULES
72 depends on HAVE_KPROBES 71 depends on HAVE_KPROBES
73 select KALLSYMS 72 select KALLSYMS
74 select EXECMEM <<
75 select NEED_TASKS_RCU <<
76 help 73 help
77 Kprobes allows you to trap at almost 74 Kprobes allows you to trap at almost any kernel address and
78 execute a callback function. regist 75 execute a callback function. register_kprobe() establishes
79 a probepoint and specifies the callb 76 a probepoint and specifies the callback. Kprobes is useful
80 for kernel debugging, non-intrusive 77 for kernel debugging, non-intrusive instrumentation and testing.
81 If in doubt, say "N". 78 If in doubt, say "N".
82 79
83 config JUMP_LABEL 80 config JUMP_LABEL
84 bool "Optimize very unlikely/likely br 81 bool "Optimize very unlikely/likely branches"
85 depends on HAVE_ARCH_JUMP_LABEL 82 depends on HAVE_ARCH_JUMP_LABEL
86 select OBJTOOL if HAVE_JUMP_LABEL_HACK !! 83 depends on CC_HAS_ASM_GOTO
87 help 84 help
88 This option enables a transparent br !! 85 This option enables a transparent branch optimization that
89 makes certain almost-always-true or !! 86 makes certain almost-always-true or almost-always-false branch
90 conditions even cheaper to execute w !! 87 conditions even cheaper to execute within the kernel.
91 !! 88
92 Certain performance-sensitive kernel !! 89 Certain performance-sensitive kernel code, such as trace points,
93 scheduler functionality, networking !! 90 scheduler functionality, networking code and KVM have such
94 branches and include support for thi !! 91 branches and include support for this optimization technique.
95 !! 92
96 If it is detected that the compiler !! 93 If it is detected that the compiler has support for "asm goto",
97 the kernel will compile such branche !! 94 the kernel will compile such branches with just a nop
98 instruction. When the condition flag !! 95 instruction. When the condition flag is toggled to true, the
99 nop will be converted to a jump inst !! 96 nop will be converted to a jump instruction to execute the
100 conditional block of instructions. !! 97 conditional block of instructions.
101 !! 98
102 This technique lowers overhead and s !! 99 This technique lowers overhead and stress on the branch prediction
103 of the processor and generally makes !! 100 of the processor and generally makes the kernel faster. The update
104 of the condition is slower, but thos !! 101 of the condition is slower, but those are always very rare.
105 102
106 ( On 32-bit x86, the necessary optio !! 103 ( On 32-bit x86, the necessary options added to the compiler
107 flags may increase the size of the !! 104 flags may increase the size of the kernel slightly. )
108 105
109 config STATIC_KEYS_SELFTEST 106 config STATIC_KEYS_SELFTEST
110 bool "Static key selftest" 107 bool "Static key selftest"
111 depends on JUMP_LABEL 108 depends on JUMP_LABEL
112 help 109 help
113 Boot time self-test of the branch pa 110 Boot time self-test of the branch patching code.
114 111
115 config STATIC_CALL_SELFTEST 112 config STATIC_CALL_SELFTEST
116 bool "Static call selftest" 113 bool "Static call selftest"
117 depends on HAVE_STATIC_CALL 114 depends on HAVE_STATIC_CALL
118 help 115 help
119 Boot time self-test of the call patc 116 Boot time self-test of the call patching code.
120 117
121 config OPTPROBES 118 config OPTPROBES
122 def_bool y 119 def_bool y
123 depends on KPROBES && HAVE_OPTPROBES 120 depends on KPROBES && HAVE_OPTPROBES
124 select NEED_TASKS_RCU !! 121 select TASKS_RCU if PREEMPTION
125 122
126 config KPROBES_ON_FTRACE 123 config KPROBES_ON_FTRACE
127 def_bool y 124 def_bool y
128 depends on KPROBES && HAVE_KPROBES_ON_ 125 depends on KPROBES && HAVE_KPROBES_ON_FTRACE
129 depends on DYNAMIC_FTRACE_WITH_REGS 126 depends on DYNAMIC_FTRACE_WITH_REGS
130 help 127 help
131 If function tracer is enabled and th !! 128 If function tracer is enabled and the arch supports full
132 passing of pt_regs to function traci !! 129 passing of pt_regs to function tracing, then kprobes can
133 optimize on top of function tracing. !! 130 optimize on top of function tracing.
134 131
135 config UPROBES 132 config UPROBES
136 def_bool n 133 def_bool n
137 depends on ARCH_SUPPORTS_UPROBES 134 depends on ARCH_SUPPORTS_UPROBES
138 help 135 help
139 Uprobes is the user-space counterpar 136 Uprobes is the user-space counterpart to kprobes: they
140 enable instrumentation applications 137 enable instrumentation applications (such as 'perf probe')
141 to establish unintrusive probes in u 138 to establish unintrusive probes in user-space binaries and
142 libraries, by executing handler func 139 libraries, by executing handler functions when the probes
143 are hit by user-space applications. 140 are hit by user-space applications.
144 141
145 ( These probes come in the form of s 142 ( These probes come in the form of single-byte breakpoints,
146 managed by the kernel and kept tra 143 managed by the kernel and kept transparent to the probed
147 application. ) 144 application. )
148 145
149 config HAVE_64BIT_ALIGNED_ACCESS 146 config HAVE_64BIT_ALIGNED_ACCESS
150 def_bool 64BIT && !HAVE_EFFICIENT_UNAL 147 def_bool 64BIT && !HAVE_EFFICIENT_UNALIGNED_ACCESS
151 help 148 help
152 Some architectures require 64 bit ac 149 Some architectures require 64 bit accesses to be 64 bit
153 aligned, which also requires structs 150 aligned, which also requires structs containing 64 bit values
154 to be 64 bit aligned too. This inclu 151 to be 64 bit aligned too. This includes some 32 bit
155 architectures which can do 64 bit ac 152 architectures which can do 64 bit accesses, as well as 64 bit
156 architectures without unaligned acce 153 architectures without unaligned access.
157 154
158 This symbol should be selected by an 155 This symbol should be selected by an architecture if 64 bit
159 accesses are required to be 64 bit a 156 accesses are required to be 64 bit aligned in this way even
160 though it is not a 64 bit architectu 157 though it is not a 64 bit architecture.
161 158
162 See Documentation/core-api/unaligned !! 159 See Documentation/unaligned-memory-access.txt for more
163 more information on the topic of una !! 160 information on the topic of unaligned memory accesses.
164 161
165 config HAVE_EFFICIENT_UNALIGNED_ACCESS 162 config HAVE_EFFICIENT_UNALIGNED_ACCESS
166 bool 163 bool
167 help 164 help
168 Some architectures are unable to per 165 Some architectures are unable to perform unaligned accesses
169 without the use of get_unaligned/put 166 without the use of get_unaligned/put_unaligned. Others are
170 unable to perform such accesses effi 167 unable to perform such accesses efficiently (e.g. trap on
171 unaligned access and require fixing 168 unaligned access and require fixing it up in the exception
172 handler.) 169 handler.)
173 170
174 This symbol should be selected by an 171 This symbol should be selected by an architecture if it can
175 perform unaligned accesses efficient 172 perform unaligned accesses efficiently to allow different
176 code paths to be selected for these 173 code paths to be selected for these cases. Some network
177 drivers, for example, could opt to n 174 drivers, for example, could opt to not fix up alignment
178 problems with received packets if do 175 problems with received packets if doing so would not help
179 much. 176 much.
180 177
181 See Documentation/core-api/unaligned 178 See Documentation/core-api/unaligned-memory-access.rst for more
182 information on the topic of unaligne 179 information on the topic of unaligned memory accesses.
183 180
184 config ARCH_USE_BUILTIN_BSWAP 181 config ARCH_USE_BUILTIN_BSWAP
185 bool 182 bool
186 help 183 help
187 Modern versions of GCC (since 4.4) h !! 184 Modern versions of GCC (since 4.4) have builtin functions
188 for handling byte-swapping. Using th !! 185 for handling byte-swapping. Using these, instead of the old
189 inline assembler that the architectu !! 186 inline assembler that the architecture code provides in the
190 __arch_bswapXX() macros, allows the !! 187 __arch_bswapXX() macros, allows the compiler to see what's
191 happening and offers more opportunit !! 188 happening and offers more opportunity for optimisation. In
192 particular, the compiler will be abl !! 189 particular, the compiler will be able to combine the byteswap
193 with a nearby load or store and use !! 190 with a nearby load or store and use load-and-swap or
194 store-and-swap instructions if the a !! 191 store-and-swap instructions if the architecture has them. It
195 should almost *never* result in code !! 192 should almost *never* result in code which is worse than the
196 hand-coded assembler in <asm/swab.h> !! 193 hand-coded assembler in <asm/swab.h>. But just in case it
197 does, the use of the builtins is opt !! 194 does, the use of the builtins is optional.
198 !! 195
199 Any architecture with load-and-swap !! 196 Any architecture with load-and-swap or store-and-swap
200 instructions should set this. And it !! 197 instructions should set this. And it shouldn't hurt to set it
201 on architectures that don't have suc !! 198 on architectures that don't have such instructions.
202 199
203 config KRETPROBES 200 config KRETPROBES
204 def_bool y 201 def_bool y
205 depends on KPROBES && (HAVE_KRETPROBES !! 202 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 <<
212 203
213 config USER_RETURN_NOTIFIER 204 config USER_RETURN_NOTIFIER
214 bool 205 bool
215 depends on HAVE_USER_RETURN_NOTIFIER 206 depends on HAVE_USER_RETURN_NOTIFIER
216 help 207 help
217 Provide a kernel-internal notificati 208 Provide a kernel-internal notification when a cpu is about to
218 switch to user mode. 209 switch to user mode.
219 210
220 config HAVE_IOREMAP_PROT 211 config HAVE_IOREMAP_PROT
221 bool 212 bool
222 213
223 config HAVE_KPROBES 214 config HAVE_KPROBES
224 bool 215 bool
225 216
226 config HAVE_KRETPROBES 217 config HAVE_KRETPROBES
227 bool 218 bool
228 219
229 config HAVE_OPTPROBES 220 config HAVE_OPTPROBES
230 bool 221 bool
231 222
232 config HAVE_KPROBES_ON_FTRACE 223 config HAVE_KPROBES_ON_FTRACE
233 bool 224 bool
234 225
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 226 config HAVE_FUNCTION_ERROR_INJECTION
244 bool 227 bool
245 228
246 config HAVE_NMI 229 config HAVE_NMI
247 bool 230 bool
248 231
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 # 232 #
259 # An arch should select this if it provides al 233 # An arch should select this if it provides all these things:
260 # 234 #
261 # task_pt_regs() in asm/process 235 # task_pt_regs() in asm/processor.h or asm/ptrace.h
262 # arch_has_single_step() if there is ha 236 # arch_has_single_step() if there is hardware single-step support
263 # arch_has_block_step() if there is ha 237 # arch_has_block_step() if there is hardware block-step support
264 # asm/syscall.h supplying asm- 238 # asm/syscall.h supplying asm-generic/syscall.h interface
265 # linux/regset.h user_regset in 239 # linux/regset.h user_regset interfaces
266 # CORE_DUMP_USE_REGSET #define'd in l 240 # CORE_DUMP_USE_REGSET #define'd in linux/elf.h
267 # TIF_SYSCALL_TRACE calls ptrace_r !! 241 # TIF_SYSCALL_TRACE calls tracehook_report_syscall_{entry,exit}
268 # TIF_NOTIFY_RESUME calls resume_u !! 242 # TIF_NOTIFY_RESUME calls tracehook_notify_resume()
>> 243 # signal delivery calls tracehook_signal_handler()
269 # 244 #
270 config HAVE_ARCH_TRACEHOOK 245 config HAVE_ARCH_TRACEHOOK
271 bool 246 bool
272 247
273 config HAVE_DMA_CONTIGUOUS 248 config HAVE_DMA_CONTIGUOUS
274 bool 249 bool
275 250
276 config GENERIC_SMP_IDLE_THREAD 251 config GENERIC_SMP_IDLE_THREAD
277 bool 252 bool
278 253
279 config GENERIC_IDLE_POLL_SETUP 254 config GENERIC_IDLE_POLL_SETUP
280 bool 255 bool
281 256
282 config ARCH_HAS_FORTIFY_SOURCE 257 config ARCH_HAS_FORTIFY_SOURCE
283 bool 258 bool
284 help 259 help
285 An architecture should select this w 260 An architecture should select this when it can successfully
286 build and run with CONFIG_FORTIFY_SO 261 build and run with CONFIG_FORTIFY_SOURCE.
287 262
288 # 263 #
289 # Select if the arch provides a historic keepi 264 # Select if the arch provides a historic keepinit alias for the retain_initrd
290 # command line option 265 # command line option
291 # 266 #
292 config ARCH_HAS_KEEPINITRD 267 config ARCH_HAS_KEEPINITRD
293 bool 268 bool
294 269
295 # 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
296 config ARCH_HAS_SET_MEMORY 271 config ARCH_HAS_SET_MEMORY
297 bool 272 bool
298 273
299 # Select if arch has all set_direct_map_invali 274 # Select if arch has all set_direct_map_invalid/default() functions
300 config ARCH_HAS_SET_DIRECT_MAP 275 config ARCH_HAS_SET_DIRECT_MAP
301 bool 276 bool
302 277
303 # 278 #
304 # Select if the architecture provides the arch 279 # Select if the architecture provides the arch_dma_set_uncached symbol to
305 # either provide an uncached segment alias for 280 # either provide an uncached segment alias for a DMA allocation, or
306 # to remap the page tables in place. 281 # to remap the page tables in place.
307 # 282 #
308 config ARCH_HAS_DMA_SET_UNCACHED 283 config ARCH_HAS_DMA_SET_UNCACHED
309 bool 284 bool
310 285
311 # 286 #
312 # Select if the architectures provides the arc 287 # Select if the architectures provides the arch_dma_clear_uncached symbol
313 # to undo an in-place page table remap for unc 288 # to undo an in-place page table remap for uncached access.
314 # 289 #
315 config ARCH_HAS_DMA_CLEAR_UNCACHED 290 config ARCH_HAS_DMA_CLEAR_UNCACHED
316 bool 291 bool
317 292
318 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
319 bool 295 bool
320 296
321 # The architecture has a per-task state that i !! 297 # Select if arch has its private alloc_task_struct() function
322 config ARCH_HAS_CPU_PASID !! 298 config ARCH_TASK_STRUCT_ALLOCATOR
323 bool 299 bool
324 select IOMMU_MM_DATA <<
325 300
326 config HAVE_ARCH_THREAD_STRUCT_WHITELIST 301 config HAVE_ARCH_THREAD_STRUCT_WHITELIST
327 bool 302 bool
>> 303 depends on !ARCH_TASK_STRUCT_ALLOCATOR
328 help 304 help
329 An architecture should select this t 305 An architecture should select this to provide hardened usercopy
330 knowledge about what region of the t 306 knowledge about what region of the thread_struct should be
331 whitelisted for copying to userspace 307 whitelisted for copying to userspace. Normally this is only the
332 FPU registers. Specifically, arch_th 308 FPU registers. Specifically, arch_thread_struct_whitelist()
333 should be implemented. Without this, 309 should be implemented. Without this, the entire thread_struct
334 field in task_struct will be left wh 310 field in task_struct will be left whitelisted.
335 311
336 # Select if arch wants to size task_struct dyn !! 312 # Select if arch has its private alloc_thread_stack() function
337 config ARCH_WANTS_DYNAMIC_TASK_STRUCT !! 313 config ARCH_THREAD_STACK_ALLOCATOR
338 bool 314 bool
339 315
340 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
341 bool 318 bool
342 help <<
343 An architecture should select this i <<
344 functions to denote that the toolcha <<
345 functions and is required for correc <<
346 319
347 config ARCH_32BIT_OFF_T 320 config ARCH_32BIT_OFF_T
348 bool 321 bool
349 depends on !64BIT 322 depends on !64BIT
350 help 323 help
351 All new 32-bit architectures should 324 All new 32-bit architectures should have 64-bit off_t type on
352 userspace side which corresponds to 325 userspace side which corresponds to the loff_t kernel type. This
353 is the requirement for modern ABIs. 326 is the requirement for modern ABIs. Some existing architectures
354 still support 32-bit off_t. This opt 327 still support 32-bit off_t. This option is enabled for all such
355 architectures explicitly. 328 architectures explicitly.
356 329
357 # Selected by 64 bit architectures which have <<
358 config ARCH_32BIT_USTAT_F_TINODE <<
359 bool <<
360 <<
361 config HAVE_ASM_MODVERSIONS 330 config HAVE_ASM_MODVERSIONS
362 bool 331 bool
363 help 332 help
364 This symbol should be selected by an 333 This symbol should be selected by an architecture if it provides
365 <asm/asm-prototypes.h> to support th 334 <asm/asm-prototypes.h> to support the module versioning for symbols
366 exported from assembly code. 335 exported from assembly code.
367 336
368 config HAVE_REGS_AND_STACK_ACCESS_API 337 config HAVE_REGS_AND_STACK_ACCESS_API
369 bool 338 bool
370 help 339 help
371 This symbol should be selected by an 340 This symbol should be selected by an architecture if it supports
372 the API needed to access registers a 341 the API needed to access registers and stack entries from pt_regs,
373 declared in asm/ptrace.h 342 declared in asm/ptrace.h
374 For example the kprobes-based event 343 For example the kprobes-based event tracer needs this API.
375 344
376 config HAVE_RSEQ 345 config HAVE_RSEQ
377 bool 346 bool
378 depends on HAVE_REGS_AND_STACK_ACCESS_ 347 depends on HAVE_REGS_AND_STACK_ACCESS_API
379 help 348 help
380 This symbol should be selected by an 349 This symbol should be selected by an architecture if it
381 supports an implementation of restar 350 supports an implementation of restartable sequences.
382 351
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 352 config HAVE_FUNCTION_ARG_ACCESS_API
390 bool 353 bool
391 help 354 help
392 This symbol should be selected by an 355 This symbol should be selected by an architecture if it supports
393 the API needed to access function ar 356 the API needed to access function arguments from pt_regs,
394 declared in asm/ptrace.h 357 declared in asm/ptrace.h
395 358
396 config HAVE_HW_BREAKPOINT 359 config HAVE_HW_BREAKPOINT
397 bool 360 bool
398 depends on PERF_EVENTS 361 depends on PERF_EVENTS
399 362
400 config HAVE_MIXED_BREAKPOINTS_REGS 363 config HAVE_MIXED_BREAKPOINTS_REGS
401 bool 364 bool
402 depends on HAVE_HW_BREAKPOINT 365 depends on HAVE_HW_BREAKPOINT
403 help 366 help
404 Depending on the arch implementation 367 Depending on the arch implementation of hardware breakpoints,
405 some of them have separate registers 368 some of them have separate registers for data and instruction
406 breakpoints addresses, others have m 369 breakpoints addresses, others have mixed registers to store
407 them but define the access type in a 370 them but define the access type in a control register.
408 Select this option if your arch impl 371 Select this option if your arch implements breakpoints under the
409 latter fashion. 372 latter fashion.
410 373
411 config HAVE_USER_RETURN_NOTIFIER 374 config HAVE_USER_RETURN_NOTIFIER
412 bool 375 bool
413 376
414 config HAVE_PERF_EVENTS_NMI 377 config HAVE_PERF_EVENTS_NMI
415 bool 378 bool
416 help 379 help
417 System hardware can generate an NMI 380 System hardware can generate an NMI using the perf event
418 subsystem. Also has support for cal 381 subsystem. Also has support for calculating CPU cycle events
419 to determine how many clock cycles i 382 to determine how many clock cycles in a given period.
420 383
421 config HAVE_HARDLOCKUP_DETECTOR_PERF 384 config HAVE_HARDLOCKUP_DETECTOR_PERF
422 bool 385 bool
423 depends on HAVE_PERF_EVENTS_NMI 386 depends on HAVE_PERF_EVENTS_NMI
424 help 387 help
425 The arch chooses to use the generic 388 The arch chooses to use the generic perf-NMI-based hardlockup
426 detector. Must define HAVE_PERF_EVEN 389 detector. Must define HAVE_PERF_EVENTS_NMI.
427 390
428 config HAVE_HARDLOCKUP_DETECTOR_ARCH !! 391 config HAVE_NMI_WATCHDOG
>> 392 depends on HAVE_NMI
429 bool 393 bool
430 help 394 help
431 The arch provides its own hardlockup !! 395 The arch provides a low level NMI watchdog. It provides
432 of the generic ones. !! 396 asm/nmi.h, and defines its own arch_touch_nmi_watchdog().
433 397
434 It uses the same command line parame !! 398 config HAVE_HARDLOCKUP_DETECTOR_ARCH
435 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.
436 405
437 config HAVE_PERF_REGS 406 config HAVE_PERF_REGS
438 bool 407 bool
439 help 408 help
440 Support selective register dumps for 409 Support selective register dumps for perf events. This includes
441 bit-mapping of each registers and a 410 bit-mapping of each registers and a unique architecture id.
442 411
443 config HAVE_PERF_USER_STACK_DUMP 412 config HAVE_PERF_USER_STACK_DUMP
444 bool 413 bool
445 help 414 help
446 Support user stack dumps for perf ev 415 Support user stack dumps for perf event samples. This needs
447 access to the user stack pointer whi 416 access to the user stack pointer which is not unified across
448 architectures. 417 architectures.
449 418
450 config HAVE_ARCH_JUMP_LABEL 419 config HAVE_ARCH_JUMP_LABEL
451 bool 420 bool
452 421
453 config HAVE_ARCH_JUMP_LABEL_RELATIVE 422 config HAVE_ARCH_JUMP_LABEL_RELATIVE
454 bool 423 bool
455 424
456 config MMU_GATHER_TABLE_FREE 425 config MMU_GATHER_TABLE_FREE
457 bool 426 bool
458 427
459 config MMU_GATHER_RCU_TABLE_FREE 428 config MMU_GATHER_RCU_TABLE_FREE
460 bool 429 bool
461 select MMU_GATHER_TABLE_FREE 430 select MMU_GATHER_TABLE_FREE
462 431
463 config MMU_GATHER_PAGE_SIZE 432 config MMU_GATHER_PAGE_SIZE
464 bool 433 bool
465 434
466 config MMU_GATHER_NO_RANGE 435 config MMU_GATHER_NO_RANGE
467 bool 436 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 <<
475 437
476 config MMU_GATHER_NO_GATHER 438 config MMU_GATHER_NO_GATHER
477 bool 439 bool
478 depends on MMU_GATHER_TABLE_FREE 440 depends on MMU_GATHER_TABLE_FREE
479 441
480 config ARCH_WANT_IRQS_OFF_ACTIVATE_MM 442 config ARCH_WANT_IRQS_OFF_ACTIVATE_MM
481 bool 443 bool
482 help 444 help
483 Temporary select until all architect 445 Temporary select until all architectures can be converted to have
484 irqs disabled over activate_mm. Arch 446 irqs disabled over activate_mm. Architectures that do IPI based TLB
485 shootdowns should enable this. 447 shootdowns should enable this.
486 448
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 449 config ARCH_HAVE_NMI_SAFE_CMPXCHG
520 bool 450 bool
521 451
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 452 config HAVE_ALIGNED_STRUCT_PAGE
535 bool 453 bool
536 help 454 help
537 This makes sure that struct pages ar 455 This makes sure that struct pages are double word aligned and that
538 e.g. the SLUB allocator can perform 456 e.g. the SLUB allocator can perform double word atomic operations
539 on a struct page for better performa 457 on a struct page for better performance. However selecting this
540 might increase the size of a struct 458 might increase the size of a struct page by a word.
541 459
542 config HAVE_CMPXCHG_LOCAL 460 config HAVE_CMPXCHG_LOCAL
543 bool 461 bool
544 462
545 config HAVE_CMPXCHG_DOUBLE 463 config HAVE_CMPXCHG_DOUBLE
546 bool 464 bool
547 465
548 config ARCH_WEAK_RELEASE_ACQUIRE 466 config ARCH_WEAK_RELEASE_ACQUIRE
549 bool 467 bool
550 468
551 config ARCH_WANT_IPC_PARSE_VERSION 469 config ARCH_WANT_IPC_PARSE_VERSION
552 bool 470 bool
553 471
554 config ARCH_WANT_COMPAT_IPC_PARSE_VERSION 472 config ARCH_WANT_COMPAT_IPC_PARSE_VERSION
555 bool 473 bool
556 474
557 config ARCH_WANT_OLD_COMPAT_IPC 475 config ARCH_WANT_OLD_COMPAT_IPC
558 select ARCH_WANT_COMPAT_IPC_PARSE_VERS 476 select ARCH_WANT_COMPAT_IPC_PARSE_VERSION
559 bool 477 bool
560 478
561 config HAVE_ARCH_SECCOMP 479 config HAVE_ARCH_SECCOMP
562 bool 480 bool
563 help 481 help
564 An arch should select this symbol to 482 An arch should select this symbol to support seccomp mode 1 (the fixed
565 syscall policy), and must provide an 483 syscall policy), and must provide an overrides for __NR_seccomp_sigreturn,
566 and compat syscalls if the asm-gener 484 and compat syscalls if the asm-generic/seccomp.h defaults need adjustment:
567 - __NR_seccomp_read_32 485 - __NR_seccomp_read_32
568 - __NR_seccomp_write_32 486 - __NR_seccomp_write_32
569 - __NR_seccomp_exit_32 487 - __NR_seccomp_exit_32
570 - __NR_seccomp_sigreturn_32 488 - __NR_seccomp_sigreturn_32
571 489
572 config HAVE_ARCH_SECCOMP_FILTER 490 config HAVE_ARCH_SECCOMP_FILTER
573 bool 491 bool
574 select HAVE_ARCH_SECCOMP 492 select HAVE_ARCH_SECCOMP
575 help 493 help
576 An arch should select this symbol if 494 An arch should select this symbol if it provides all of these things:
577 - all the requirements for HAVE_ARCH 495 - all the requirements for HAVE_ARCH_SECCOMP
578 - syscall_get_arch() 496 - syscall_get_arch()
579 - syscall_get_arguments() 497 - syscall_get_arguments()
580 - syscall_rollback() 498 - syscall_rollback()
581 - syscall_set_return_value() 499 - syscall_set_return_value()
582 - SIGSYS siginfo_t support 500 - SIGSYS siginfo_t support
583 - secure_computing is called from a 501 - secure_computing is called from a ptrace_event()-safe context
584 - secure_computing return value is c 502 - secure_computing return value is checked and a return value of -1
585 results in the system call being s 503 results in the system call being skipped immediately.
586 - seccomp syscall wired up 504 - seccomp syscall wired up
587 - if !HAVE_SPARSE_SYSCALL_NR, have S 505 - if !HAVE_SPARSE_SYSCALL_NR, have SECCOMP_ARCH_NATIVE,
588 SECCOMP_ARCH_NATIVE_NR, SECCOMP_AR 506 SECCOMP_ARCH_NATIVE_NR, SECCOMP_ARCH_NATIVE_NAME defined. If
589 COMPAT is supported, have the SECC 507 COMPAT is supported, have the SECCOMP_ARCH_COMPAT* defines too.
590 508
591 config SECCOMP 509 config SECCOMP
592 prompt "Enable seccomp to safely execu 510 prompt "Enable seccomp to safely execute untrusted bytecode"
593 def_bool y 511 def_bool y
594 depends on HAVE_ARCH_SECCOMP 512 depends on HAVE_ARCH_SECCOMP
595 help 513 help
596 This kernel feature is useful for nu 514 This kernel feature is useful for number crunching applications
597 that may need to handle untrusted by 515 that may need to handle untrusted bytecode during their
598 execution. By using pipes or other t 516 execution. By using pipes or other transports made available
599 to the process as file descriptors s 517 to the process as file descriptors supporting the read/write
600 syscalls, it's possible to isolate t 518 syscalls, it's possible to isolate those applications in their
601 own address space using seccomp. Onc 519 own address space using seccomp. Once seccomp is enabled via
602 prctl(PR_SET_SECCOMP) or the seccomp 520 prctl(PR_SET_SECCOMP) or the seccomp() syscall, it cannot be
603 disabled and the task is only allowe 521 disabled and the task is only allowed to execute a few safe
604 syscalls defined by each seccomp mod 522 syscalls defined by each seccomp mode.
605 523
606 If unsure, say Y. 524 If unsure, say Y.
607 525
608 config SECCOMP_FILTER 526 config SECCOMP_FILTER
609 def_bool y 527 def_bool y
610 depends on HAVE_ARCH_SECCOMP_FILTER && 528 depends on HAVE_ARCH_SECCOMP_FILTER && SECCOMP && NET
611 help 529 help
612 Enable tasks to build secure computi 530 Enable tasks to build secure computing environments defined
613 in terms of Berkeley Packet Filter p 531 in terms of Berkeley Packet Filter programs which implement
614 task-defined system call filtering p 532 task-defined system call filtering polices.
615 533
616 See Documentation/userspace-api/secc 534 See Documentation/userspace-api/seccomp_filter.rst for details.
617 535
618 config SECCOMP_CACHE_DEBUG 536 config SECCOMP_CACHE_DEBUG
619 bool "Show seccomp filter cache status 537 bool "Show seccomp filter cache status in /proc/pid/seccomp_cache"
620 depends on SECCOMP_FILTER && !HAVE_SPA 538 depends on SECCOMP_FILTER && !HAVE_SPARSE_SYSCALL_NR
621 depends on PROC_FS 539 depends on PROC_FS
622 help 540 help
623 This enables the /proc/pid/seccomp_c 541 This enables the /proc/pid/seccomp_cache interface to monitor
624 seccomp cache data. The file format 542 seccomp cache data. The file format is subject to change. Reading
625 the file requires CAP_SYS_ADMIN. 543 the file requires CAP_SYS_ADMIN.
626 544
627 This option is for debugging only. E 545 This option is for debugging only. Enabling presents the risk that
628 an adversary may be able to infer th 546 an adversary may be able to infer the seccomp filter logic.
629 547
630 If unsure, say N. 548 If unsure, say N.
631 549
632 config HAVE_ARCH_STACKLEAK 550 config HAVE_ARCH_STACKLEAK
633 bool 551 bool
634 help 552 help
635 An architecture should select this i 553 An architecture should select this if it has the code which
636 fills the used part of the kernel st 554 fills the used part of the kernel stack with the STACKLEAK_POISON
637 value before returning from system c 555 value before returning from system calls.
638 556
639 config HAVE_STACKPROTECTOR 557 config HAVE_STACKPROTECTOR
640 bool 558 bool
641 help 559 help
642 An arch should select this symbol if 560 An arch should select this symbol if:
643 - it has implemented a stack canary 561 - it has implemented a stack canary (e.g. __stack_chk_guard)
644 562
645 config STACKPROTECTOR 563 config STACKPROTECTOR
646 bool "Stack Protector buffer overflow 564 bool "Stack Protector buffer overflow detection"
647 depends on HAVE_STACKPROTECTOR 565 depends on HAVE_STACKPROTECTOR
648 depends on $(cc-option,-fstack-protect 566 depends on $(cc-option,-fstack-protector)
649 default y 567 default y
650 help 568 help
651 This option turns on the "stack-prot 569 This option turns on the "stack-protector" GCC feature. This
652 feature puts, at the beginning of fu 570 feature puts, at the beginning of functions, a canary value on
653 the stack just before the return add 571 the stack just before the return address, and validates
654 the value just before actually retur 572 the value just before actually returning. Stack based buffer
655 overflows (that need to overwrite th 573 overflows (that need to overwrite this return address) now also
656 overwrite the canary, which gets det 574 overwrite the canary, which gets detected and the attack is then
657 neutralized via a kernel panic. 575 neutralized via a kernel panic.
658 576
659 Functions will have the stack-protec 577 Functions will have the stack-protector canary logic added if they
660 have an 8-byte or larger character a 578 have an 8-byte or larger character array on the stack.
661 579
662 This feature requires gcc version 4. 580 This feature requires gcc version 4.2 or above, or a distribution
663 gcc with the feature backported ("-f 581 gcc with the feature backported ("-fstack-protector").
664 582
665 On an x86 "defconfig" build, this fe 583 On an x86 "defconfig" build, this feature adds canary checks to
666 about 3% of all kernel functions, wh 584 about 3% of all kernel functions, which increases kernel code size
667 by about 0.3%. 585 by about 0.3%.
668 586
669 config STACKPROTECTOR_STRONG 587 config STACKPROTECTOR_STRONG
670 bool "Strong Stack Protector" 588 bool "Strong Stack Protector"
671 depends on STACKPROTECTOR 589 depends on STACKPROTECTOR
672 depends on $(cc-option,-fstack-protect 590 depends on $(cc-option,-fstack-protector-strong)
673 default y 591 default y
674 help 592 help
675 Functions will have the stack-protec 593 Functions will have the stack-protector canary logic added in any
676 of the following conditions: 594 of the following conditions:
677 595
678 - local variable's address used as p 596 - local variable's address used as part of the right hand side of an
679 assignment or function argument 597 assignment or function argument
680 - local variable is an array (or uni 598 - local variable is an array (or union containing an array),
681 regardless of array type or length 599 regardless of array type or length
682 - uses register local variables 600 - uses register local variables
683 601
684 This feature requires gcc version 4. 602 This feature requires gcc version 4.9 or above, or a distribution
685 gcc with the feature backported ("-f 603 gcc with the feature backported ("-fstack-protector-strong").
686 604
687 On an x86 "defconfig" build, this fe 605 On an x86 "defconfig" build, this feature adds canary checks to
688 about 20% of all kernel functions, w 606 about 20% of all kernel functions, which increases the kernel code
689 size by about 2%. 607 size by about 2%.
690 608
691 config ARCH_SUPPORTS_SHADOW_CALL_STACK 609 config ARCH_SUPPORTS_SHADOW_CALL_STACK
692 bool 610 bool
693 help 611 help
694 An architecture should select this i !! 612 An architecture should select this if it supports Clang's Shadow
695 Shadow Call Stack and implements run !! 613 Call Stack and implements runtime support for shadow stack
696 switching. 614 switching.
697 615
698 config SHADOW_CALL_STACK 616 config SHADOW_CALL_STACK
699 bool "Shadow Call Stack" !! 617 bool "Clang Shadow Call Stack"
700 depends on ARCH_SUPPORTS_SHADOW_CALL_S !! 618 depends on CC_IS_CLANG && ARCH_SUPPORTS_SHADOW_CALL_STACK
701 depends on DYNAMIC_FTRACE_WITH_ARGS || !! 619 depends on DYNAMIC_FTRACE_WITH_REGS || !FUNCTION_GRAPH_TRACER
702 depends on MMU !! 620 help
703 help !! 621 This option enables Clang's Shadow Call Stack, which uses a
704 This option enables the compiler's S !! 622 shadow stack to protect function return addresses from being
705 uses a shadow stack to protect funct !! 623 overwritten by an attacker. More information can be found in
706 being overwritten by an attacker. Mo !! 624 Clang's documentation:
707 in the compiler's documentation: <<
708 625
709 - Clang: https://clang.llvm.org/docs !! 626 https://clang.llvm.org/docs/ShadowCallStack.html
710 - GCC: https://gcc.gnu.org/onlinedoc <<
711 627
712 Note that security guarantees in the 628 Note that security guarantees in the kernel differ from the
713 ones documented for user space. The 629 ones documented for user space. The kernel must store addresses
714 of shadow stacks in memory, which me 630 of shadow stacks in memory, which means an attacker capable of
715 reading and writing arbitrary memory 631 reading and writing arbitrary memory may be able to locate them
716 and hijack control flow by modifying 632 and hijack control flow by modifying the stacks.
717 633
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 634 config HAVE_ARCH_WITHIN_STACK_FRAMES
879 bool 635 bool
880 help 636 help
881 An architecture should select this i 637 An architecture should select this if it can walk the kernel stack
882 frames to determine if an object is 638 frames to determine if an object is part of either the arguments
883 or local variables (i.e. that it exc 639 or local variables (i.e. that it excludes saved return addresses,
884 and similar) by implementing an inli 640 and similar) by implementing an inline arch_within_stack_frames(),
885 which is used by CONFIG_HARDENED_USE 641 which is used by CONFIG_HARDENED_USERCOPY.
886 642
887 config HAVE_CONTEXT_TRACKING_USER !! 643 config HAVE_CONTEXT_TRACKING
888 bool 644 bool
889 help 645 help
890 Provide kernel/user boundaries probe 646 Provide kernel/user boundaries probes necessary for subsystems
891 that need it, such as userspace RCU 647 that need it, such as userspace RCU extended quiescent state.
892 Syscalls need to be wrapped inside u 648 Syscalls need to be wrapped inside user_exit()-user_enter(), either
893 optimized behind static key or throu 649 optimized behind static key or through the slow path using TIF_NOHZ
894 flag. Exceptions handlers must be wr 650 flag. Exceptions handlers must be wrapped as well. Irqs are already
895 protected inside ct_irq_enter/ct_irq !! 651 protected inside rcu_irq_enter/rcu_irq_exit() but preemption or signal
896 handling on irq exit still need to b 652 handling on irq exit still need to be protected.
897 653
898 config HAVE_CONTEXT_TRACKING_USER_OFFSTACK !! 654 config HAVE_CONTEXT_TRACKING_OFFSTACK
899 bool 655 bool
900 help 656 help
901 Architecture neither relies on excep 657 Architecture neither relies on exception_enter()/exception_exit()
902 nor on schedule_user(). Also preempt 658 nor on schedule_user(). Also preempt_schedule_notrace() and
903 preempt_schedule_irq() can't be call 659 preempt_schedule_irq() can't be called in a preemptible section
904 while context tracking is CT_STATE_U !! 660 while context tracking is CONTEXT_USER. This feature reflects a sane
905 entry implementation where the follo 661 entry implementation where the following requirements are met on
906 critical entry code, ie: before user 662 critical entry code, ie: before user_exit() or after user_enter():
907 663
908 - Critical entry code isn't preempti 664 - Critical entry code isn't preemptible (or better yet:
909 not interruptible). 665 not interruptible).
910 - No use of RCU read side critical s !! 666 - No use of RCU read side critical sections, unless rcu_nmi_enter()
911 got called. 667 got called.
912 - No use of instrumentation, unless 668 - No use of instrumentation, unless instrumentation_begin() got
913 called. 669 called.
914 670
915 config HAVE_TIF_NOHZ 671 config HAVE_TIF_NOHZ
916 bool 672 bool
917 help 673 help
918 Arch relies on TIF_NOHZ and syscall 674 Arch relies on TIF_NOHZ and syscall slow path to implement context
919 tracking calls to user_enter()/user_ 675 tracking calls to user_enter()/user_exit().
920 676
921 config HAVE_VIRT_CPU_ACCOUNTING 677 config HAVE_VIRT_CPU_ACCOUNTING
922 bool 678 bool
923 679
924 config HAVE_VIRT_CPU_ACCOUNTING_IDLE 680 config HAVE_VIRT_CPU_ACCOUNTING_IDLE
925 bool 681 bool
926 help 682 help
927 Architecture has its own way to acco 683 Architecture has its own way to account idle CPU time and therefore
928 doesn't implement vtime_account_idle 684 doesn't implement vtime_account_idle().
929 685
930 config ARCH_HAS_SCALED_CPUTIME 686 config ARCH_HAS_SCALED_CPUTIME
931 bool 687 bool
932 688
933 config HAVE_VIRT_CPU_ACCOUNTING_GEN 689 config HAVE_VIRT_CPU_ACCOUNTING_GEN
934 bool 690 bool
935 default y if 64BIT 691 default y if 64BIT
936 help 692 help
937 With VIRT_CPU_ACCOUNTING_GEN, cputim 693 With VIRT_CPU_ACCOUNTING_GEN, cputime_t becomes 64-bit.
938 Before enabling this option, arch co 694 Before enabling this option, arch code must be audited
939 to ensure there are no races in conc 695 to ensure there are no races in concurrent read/write of
940 cputime_t. For example, reading/writ 696 cputime_t. For example, reading/writing 64-bit cputime_t on
941 some 32-bit arches may require multi 697 some 32-bit arches may require multiple accesses, so proper
942 locking is needed to protect against 698 locking is needed to protect against concurrent accesses.
943 699
944 config HAVE_IRQ_TIME_ACCOUNTING 700 config HAVE_IRQ_TIME_ACCOUNTING
945 bool 701 bool
946 help 702 help
947 Archs need to ensure they use a high 703 Archs need to ensure they use a high enough resolution clock to
948 support irq time accounting and then 704 support irq time accounting and then call enable_sched_clock_irqtime().
949 705
950 config HAVE_MOVE_PUD 706 config HAVE_MOVE_PUD
951 bool 707 bool
952 help 708 help
953 Architectures that select this are a 709 Architectures that select this are able to move page tables at the
954 PUD level. If there are only 3 page 710 PUD level. If there are only 3 page table levels, the move effectively
955 happens at the PGD level. 711 happens at the PGD level.
956 712
957 config HAVE_MOVE_PMD 713 config HAVE_MOVE_PMD
958 bool 714 bool
959 help 715 help
960 Archs that select this are able to m 716 Archs that select this are able to move page tables at the PMD level.
961 717
962 config HAVE_ARCH_TRANSPARENT_HUGEPAGE 718 config HAVE_ARCH_TRANSPARENT_HUGEPAGE
963 bool 719 bool
964 720
965 config HAVE_ARCH_TRANSPARENT_HUGEPAGE_PUD 721 config HAVE_ARCH_TRANSPARENT_HUGEPAGE_PUD
966 bool 722 bool
967 723
968 config HAVE_ARCH_HUGE_VMAP 724 config HAVE_ARCH_HUGE_VMAP
969 bool 725 bool
970 726
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 727 config ARCH_WANT_HUGE_PMD_SHARE
981 bool 728 bool
982 729
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 730 config HAVE_ARCH_SOFT_DIRTY
992 bool 731 bool
993 732
994 config HAVE_MOD_ARCH_SPECIFIC 733 config HAVE_MOD_ARCH_SPECIFIC
995 bool 734 bool
996 help 735 help
997 The arch uses struct mod_arch_specif 736 The arch uses struct mod_arch_specific to store data. Many arches
998 just need a simple module loader wit 737 just need a simple module loader without arch specific data - those
999 should not enable this. 738 should not enable this.
1000 739
1001 config MODULES_USE_ELF_RELA 740 config MODULES_USE_ELF_RELA
1002 bool 741 bool
1003 help 742 help
1004 Modules only use ELF RELA relocatio 743 Modules only use ELF RELA relocations. Modules with ELF REL
1005 relocations will give an error. 744 relocations will give an error.
1006 745
1007 config MODULES_USE_ELF_REL 746 config MODULES_USE_ELF_REL
1008 bool 747 bool
1009 help 748 help
1010 Modules only use ELF REL relocation 749 Modules only use ELF REL relocations. Modules with ELF RELA
1011 relocations will give an error. 750 relocations will give an error.
1012 751
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 752 config HAVE_IRQ_EXIT_ON_IRQ_STACK
1028 bool 753 bool
1029 help 754 help
1030 Architecture doesn't only execute t 755 Architecture doesn't only execute the irq handler on the irq stack
1031 but also irq_exit(). This way we ca 756 but also irq_exit(). This way we can process softirqs on this irq
1032 stack instead of switching to a new 757 stack instead of switching to a new one when we call __do_softirq()
1033 in the end of an hardirq. 758 in the end of an hardirq.
1034 This spares a stack switch and impr 759 This spares a stack switch and improves cache usage on softirq
1035 processing. 760 processing.
1036 761
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 762 config PGTABLE_LEVELS
1054 int 763 int
1055 default 2 764 default 2
1056 765
1057 config ARCH_HAS_ELF_RANDOMIZE 766 config ARCH_HAS_ELF_RANDOMIZE
1058 bool 767 bool
1059 help 768 help
1060 An architecture supports choosing r 769 An architecture supports choosing randomized locations for
1061 stack, mmap, brk, and ET_DYN. Defin 770 stack, mmap, brk, and ET_DYN. Defined functions:
1062 - arch_mmap_rnd() 771 - arch_mmap_rnd()
1063 - arch_randomize_brk() 772 - arch_randomize_brk()
1064 773
1065 config HAVE_ARCH_MMAP_RND_BITS 774 config HAVE_ARCH_MMAP_RND_BITS
1066 bool 775 bool
1067 help 776 help
1068 An arch should select this symbol i 777 An arch should select this symbol if it supports setting a variable
1069 number of bits for use in establish 778 number of bits for use in establishing the base address for mmap
1070 allocations, has MMU enabled and pr 779 allocations, has MMU enabled and provides values for both:
1071 - ARCH_MMAP_RND_BITS_MIN 780 - ARCH_MMAP_RND_BITS_MIN
1072 - ARCH_MMAP_RND_BITS_MAX 781 - ARCH_MMAP_RND_BITS_MAX
1073 782
1074 config HAVE_EXIT_THREAD 783 config HAVE_EXIT_THREAD
1075 bool 784 bool
1076 help 785 help
1077 An architecture implements exit_thr 786 An architecture implements exit_thread.
1078 787
1079 config ARCH_MMAP_RND_BITS_MIN 788 config ARCH_MMAP_RND_BITS_MIN
1080 int 789 int
1081 790
1082 config ARCH_MMAP_RND_BITS_MAX 791 config ARCH_MMAP_RND_BITS_MAX
1083 int 792 int
1084 793
1085 config ARCH_MMAP_RND_BITS_DEFAULT 794 config ARCH_MMAP_RND_BITS_DEFAULT
1086 int 795 int
1087 796
1088 config ARCH_MMAP_RND_BITS 797 config ARCH_MMAP_RND_BITS
1089 int "Number of bits to use for ASLR o 798 int "Number of bits to use for ASLR of mmap base address" if EXPERT
1090 range ARCH_MMAP_RND_BITS_MIN ARCH_MMA 799 range ARCH_MMAP_RND_BITS_MIN ARCH_MMAP_RND_BITS_MAX
1091 default ARCH_MMAP_RND_BITS_DEFAULT if 800 default ARCH_MMAP_RND_BITS_DEFAULT if ARCH_MMAP_RND_BITS_DEFAULT
1092 default ARCH_MMAP_RND_BITS_MIN 801 default ARCH_MMAP_RND_BITS_MIN
1093 depends on HAVE_ARCH_MMAP_RND_BITS 802 depends on HAVE_ARCH_MMAP_RND_BITS
1094 help 803 help
1095 This value can be used to select th 804 This value can be used to select the number of bits to use to
1096 determine the random offset to the 805 determine the random offset to the base address of vma regions
1097 resulting from mmap allocations. Th 806 resulting from mmap allocations. This value will be bounded
1098 by the architecture's minimum and m 807 by the architecture's minimum and maximum supported values.
1099 808
1100 This value can be changed after boo 809 This value can be changed after boot using the
1101 /proc/sys/vm/mmap_rnd_bits tunable 810 /proc/sys/vm/mmap_rnd_bits tunable
1102 811
1103 config HAVE_ARCH_MMAP_RND_COMPAT_BITS 812 config HAVE_ARCH_MMAP_RND_COMPAT_BITS
1104 bool 813 bool
1105 help 814 help
1106 An arch should select this symbol i 815 An arch should select this symbol if it supports running applications
1107 in compatibility mode, supports set 816 in compatibility mode, supports setting a variable number of bits for
1108 use in establishing the base addres 817 use in establishing the base address for mmap allocations, has MMU
1109 enabled and provides values for bot 818 enabled and provides values for both:
1110 - ARCH_MMAP_RND_COMPAT_BITS_MIN 819 - ARCH_MMAP_RND_COMPAT_BITS_MIN
1111 - ARCH_MMAP_RND_COMPAT_BITS_MAX 820 - ARCH_MMAP_RND_COMPAT_BITS_MAX
1112 821
1113 config ARCH_MMAP_RND_COMPAT_BITS_MIN 822 config ARCH_MMAP_RND_COMPAT_BITS_MIN
1114 int 823 int
1115 824
1116 config ARCH_MMAP_RND_COMPAT_BITS_MAX 825 config ARCH_MMAP_RND_COMPAT_BITS_MAX
1117 int 826 int
1118 827
1119 config ARCH_MMAP_RND_COMPAT_BITS_DEFAULT 828 config ARCH_MMAP_RND_COMPAT_BITS_DEFAULT
1120 int 829 int
1121 830
1122 config ARCH_MMAP_RND_COMPAT_BITS 831 config ARCH_MMAP_RND_COMPAT_BITS
1123 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
1124 range ARCH_MMAP_RND_COMPAT_BITS_MIN A 833 range ARCH_MMAP_RND_COMPAT_BITS_MIN ARCH_MMAP_RND_COMPAT_BITS_MAX
1125 default ARCH_MMAP_RND_COMPAT_BITS_DEF 834 default ARCH_MMAP_RND_COMPAT_BITS_DEFAULT if ARCH_MMAP_RND_COMPAT_BITS_DEFAULT
1126 default ARCH_MMAP_RND_COMPAT_BITS_MIN 835 default ARCH_MMAP_RND_COMPAT_BITS_MIN
1127 depends on HAVE_ARCH_MMAP_RND_COMPAT_ 836 depends on HAVE_ARCH_MMAP_RND_COMPAT_BITS
1128 help 837 help
1129 This value can be used to select th 838 This value can be used to select the number of bits to use to
1130 determine the random offset to the 839 determine the random offset to the base address of vma regions
1131 resulting from mmap allocations for 840 resulting from mmap allocations for compatible applications This
1132 value will be bounded by the archit 841 value will be bounded by the architecture's minimum and maximum
1133 supported values. 842 supported values.
1134 843
1135 This value can be changed after boo 844 This value can be changed after boot using the
1136 /proc/sys/vm/mmap_rnd_compat_bits t 845 /proc/sys/vm/mmap_rnd_compat_bits tunable
1137 846
1138 config HAVE_ARCH_COMPAT_MMAP_BASES 847 config HAVE_ARCH_COMPAT_MMAP_BASES
1139 bool 848 bool
1140 help 849 help
1141 This allows 64bit applications to i 850 This allows 64bit applications to invoke 32-bit mmap() syscall
1142 and vice-versa 32-bit applications 851 and vice-versa 32-bit applications to call 64-bit mmap().
1143 Required for applications doing dif 852 Required for applications doing different bitness syscalls.
1144 853
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 854 # This allows to use a set of generic functions to determine mmap base
1247 # address by giving priority to top-down sche 855 # address by giving priority to top-down scheme only if the process
1248 # is not in legacy mode (compat task, unlimit 856 # is not in legacy mode (compat task, unlimited stack size or
1249 # sysctl_legacy_va_layout). 857 # sysctl_legacy_va_layout).
1250 # Architecture that selects this option can p 858 # Architecture that selects this option can provide its own version of:
1251 # - STACK_RND_MASK 859 # - STACK_RND_MASK
1252 config ARCH_WANT_DEFAULT_TOPDOWN_MMAP_LAYOUT 860 config ARCH_WANT_DEFAULT_TOPDOWN_MMAP_LAYOUT
1253 bool 861 bool
1254 depends on MMU 862 depends on MMU
1255 select ARCH_HAS_ELF_RANDOMIZE 863 select ARCH_HAS_ELF_RANDOMIZE
1256 864
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 865 config HAVE_STACK_VALIDATION
1274 bool 866 bool
1275 help 867 help
1276 Architecture supports objtool compi !! 868 Architecture supports the 'objtool check' host tool command, which
1277 validation. !! 869 performs compile-time stack metadata validation.
1278 870
1279 config HAVE_RELIABLE_STACKTRACE 871 config HAVE_RELIABLE_STACKTRACE
1280 bool 872 bool
1281 help 873 help
1282 Architecture has either save_stack_ 874 Architecture has either save_stack_trace_tsk_reliable() or
1283 arch_stack_walk_reliable() function 875 arch_stack_walk_reliable() function which only returns a stack trace
1284 if it can guarantee the trace is re 876 if it can guarantee the trace is reliable.
1285 877
1286 config HAVE_ARCH_HASH 878 config HAVE_ARCH_HASH
1287 bool 879 bool
1288 default n 880 default n
1289 help 881 help
1290 If this is set, the architecture pr 882 If this is set, the architecture provides an <asm/hash.h>
1291 file which provides platform-specif 883 file which provides platform-specific implementations of some
1292 functions in <linux/hash.h> or fs/n 884 functions in <linux/hash.h> or fs/namei.c.
1293 885
1294 config HAVE_ARCH_NVRAM_OPS 886 config HAVE_ARCH_NVRAM_OPS
1295 bool 887 bool
1296 888
1297 config ISA_BUS_API 889 config ISA_BUS_API
1298 def_bool ISA 890 def_bool ISA
1299 891
1300 # 892 #
1301 # ABI hall of shame 893 # ABI hall of shame
1302 # 894 #
1303 config CLONE_BACKWARDS 895 config CLONE_BACKWARDS
1304 bool 896 bool
1305 help 897 help
1306 Architecture has tls passed as the 898 Architecture has tls passed as the 4th argument of clone(2),
1307 not the 5th one. 899 not the 5th one.
1308 900
1309 config CLONE_BACKWARDS2 901 config CLONE_BACKWARDS2
1310 bool 902 bool
1311 help 903 help
1312 Architecture has the first two argu 904 Architecture has the first two arguments of clone(2) swapped.
1313 905
1314 config CLONE_BACKWARDS3 906 config CLONE_BACKWARDS3
1315 bool 907 bool
1316 help 908 help
1317 Architecture has tls passed as the 909 Architecture has tls passed as the 3rd argument of clone(2),
1318 not the 5th one. 910 not the 5th one.
1319 911
1320 config ODD_RT_SIGACTION 912 config ODD_RT_SIGACTION
1321 bool 913 bool
1322 help 914 help
1323 Architecture has unusual rt_sigacti 915 Architecture has unusual rt_sigaction(2) arguments
1324 916
1325 config OLD_SIGSUSPEND 917 config OLD_SIGSUSPEND
1326 bool 918 bool
1327 help 919 help
1328 Architecture has old sigsuspend(2) 920 Architecture has old sigsuspend(2) syscall, of one-argument variety
1329 921
1330 config OLD_SIGSUSPEND3 922 config OLD_SIGSUSPEND3
1331 bool 923 bool
1332 help 924 help
1333 Even weirder antique ABI - three-ar 925 Even weirder antique ABI - three-argument sigsuspend(2)
1334 926
1335 config OLD_SIGACTION 927 config OLD_SIGACTION
1336 bool 928 bool
1337 help 929 help
1338 Architecture has old sigaction(2) s 930 Architecture has old sigaction(2) syscall. Nope, not the same
1339 as OLD_SIGSUSPEND | OLD_SIGSUSPEND3 931 as OLD_SIGSUSPEND | OLD_SIGSUSPEND3 - alpha has sigsuspend(2),
1340 but fairly different variant of sig 932 but fairly different variant of sigaction(2), thanks to OSF/1
1341 compatibility... 933 compatibility...
1342 934
1343 config COMPAT_OLD_SIGACTION 935 config COMPAT_OLD_SIGACTION
1344 bool 936 bool
1345 937
1346 config COMPAT_32BIT_TIME 938 config COMPAT_32BIT_TIME
1347 bool "Provide system calls for 32-bit 939 bool "Provide system calls for 32-bit time_t"
1348 default !64BIT || COMPAT 940 default !64BIT || COMPAT
1349 help 941 help
1350 This enables 32 bit time_t support 942 This enables 32 bit time_t support in addition to 64 bit time_t support.
1351 This is relevant on all 32-bit arch 943 This is relevant on all 32-bit architectures, and 64-bit architectures
1352 as part of compat syscall handling. 944 as part of compat syscall handling.
1353 945
1354 config ARCH_NO_PREEMPT 946 config ARCH_NO_PREEMPT
1355 bool 947 bool
1356 948
1357 config ARCH_SUPPORTS_RT 949 config ARCH_SUPPORTS_RT
1358 bool 950 bool
1359 951
1360 config CPU_NO_EFFICIENT_FFS 952 config CPU_NO_EFFICIENT_FFS
1361 def_bool n 953 def_bool n
1362 954
1363 config HAVE_ARCH_VMAP_STACK 955 config HAVE_ARCH_VMAP_STACK
1364 def_bool n 956 def_bool n
1365 help 957 help
1366 An arch should select this symbol i 958 An arch should select this symbol if it can support kernel stacks
1367 in vmalloc space. This means: 959 in vmalloc space. This means:
1368 960
1369 - vmalloc space must be large enoug 961 - vmalloc space must be large enough to hold many kernel stacks.
1370 This may rule out many 32-bit arc 962 This may rule out many 32-bit architectures.
1371 963
1372 - Stacks in vmalloc space need to w 964 - Stacks in vmalloc space need to work reliably. For example, if
1373 vmap page tables are created on d 965 vmap page tables are created on demand, either this mechanism
1374 needs to work while the stack poi 966 needs to work while the stack points to a virtual address with
1375 unpopulated page tables or arch c 967 unpopulated page tables or arch code (switch_to() and switch_mm(),
1376 most likely) needs to ensure that 968 most likely) needs to ensure that the stack's page table entries
1377 are populated before running on a 969 are populated before running on a possibly unpopulated stack.
1378 970
1379 - If the stack overflows into a gua 971 - If the stack overflows into a guard page, something reasonable
1380 should happen. The definition of 972 should happen. The definition of "reasonable" is flexible, but
1381 instantly rebooting without loggi 973 instantly rebooting without logging anything would be unfriendly.
1382 974
1383 config VMAP_STACK 975 config VMAP_STACK
1384 default y 976 default y
1385 bool "Use a virtually-mapped stack" 977 bool "Use a virtually-mapped stack"
1386 depends on HAVE_ARCH_VMAP_STACK 978 depends on HAVE_ARCH_VMAP_STACK
1387 depends on !KASAN || KASAN_HW_TAGS || 979 depends on !KASAN || KASAN_HW_TAGS || KASAN_VMALLOC
1388 help 980 help
1389 Enable this if you want the use vir 981 Enable this if you want the use virtually-mapped kernel stacks
1390 with guard pages. This causes kern 982 with guard pages. This causes kernel stack overflows to be
1391 caught immediately rather than caus 983 caught immediately rather than causing difficult-to-diagnose
1392 corruption. 984 corruption.
1393 985
1394 To use this with software KASAN mod 986 To use this with software KASAN modes, the architecture must support
1395 backing virtual mappings with real 987 backing virtual mappings with real shadow memory, and KASAN_VMALLOC
1396 must be enabled. 988 must be enabled.
1397 989
1398 config HAVE_ARCH_RANDOMIZE_KSTACK_OFFSET <<
1399 def_bool n <<
1400 help <<
1401 An arch should select this symbol i <<
1402 offset randomization with calls to <<
1403 during syscall entry and choose_ran <<
1404 syscall exit. Careful removal of -f <<
1405 -fstack-protector should also be ap <<
1406 closely examined, as the artificial <<
1407 to the compiler, so it will attempt <<
1408 of the static branch state. <<
1409 <<
1410 config RANDOMIZE_KSTACK_OFFSET <<
1411 bool "Support for randomizing kernel <<
1412 default y <<
1413 depends on HAVE_ARCH_RANDOMIZE_KSTACK <<
1414 depends on INIT_STACK_NONE || !CC_IS_ <<
1415 help <<
1416 The kernel stack offset can be rand <<
1417 roughly 5 bits of entropy, frustrat <<
1418 attacks that depend on stack addres <<
1419 cross-syscall address exposures. <<
1420 <<
1421 The feature is controlled via the " <<
1422 kernel boot param, and if turned of <<
1423 of static branches (see JUMP_LABEL) <<
1424 <<
1425 If unsure, say Y. <<
1426 <<
1427 config RANDOMIZE_KSTACK_OFFSET_DEFAULT <<
1428 bool "Default state of kernel stack o <<
1429 depends on RANDOMIZE_KSTACK_OFFSET <<
1430 help <<
1431 Kernel stack offset randomization i <<
1432 "randomize_kstack_offset=on/off", a <<
1433 boot state. <<
1434 <<
1435 config ARCH_OPTIONAL_KERNEL_RWX 990 config ARCH_OPTIONAL_KERNEL_RWX
1436 def_bool n 991 def_bool n
1437 992
1438 config ARCH_OPTIONAL_KERNEL_RWX_DEFAULT 993 config ARCH_OPTIONAL_KERNEL_RWX_DEFAULT
1439 def_bool n 994 def_bool n
1440 995
1441 config ARCH_HAS_STRICT_KERNEL_RWX 996 config ARCH_HAS_STRICT_KERNEL_RWX
1442 def_bool n 997 def_bool n
1443 998
1444 config STRICT_KERNEL_RWX 999 config STRICT_KERNEL_RWX
1445 bool "Make kernel text and rodata rea 1000 bool "Make kernel text and rodata read-only" if ARCH_OPTIONAL_KERNEL_RWX
1446 depends on ARCH_HAS_STRICT_KERNEL_RWX 1001 depends on ARCH_HAS_STRICT_KERNEL_RWX
1447 default !ARCH_OPTIONAL_KERNEL_RWX || 1002 default !ARCH_OPTIONAL_KERNEL_RWX || ARCH_OPTIONAL_KERNEL_RWX_DEFAULT
1448 help 1003 help
1449 If this is set, kernel text and rod 1004 If this is set, kernel text and rodata memory will be made read-only,
1450 and non-text memory will be made no 1005 and non-text memory will be made non-executable. This provides
1451 protection against certain security 1006 protection against certain security exploits (e.g. executing the heap
1452 or modifying text) 1007 or modifying text)
1453 1008
1454 These features are considered stand 1009 These features are considered standard security practice these days.
1455 You should say Y here in almost all 1010 You should say Y here in almost all cases.
1456 1011
1457 config ARCH_HAS_STRICT_MODULE_RWX 1012 config ARCH_HAS_STRICT_MODULE_RWX
1458 def_bool n 1013 def_bool n
1459 1014
1460 config STRICT_MODULE_RWX 1015 config STRICT_MODULE_RWX
1461 bool "Set loadable kernel module data 1016 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 1017 depends on ARCH_HAS_STRICT_MODULE_RWX && MODULES
1463 default !ARCH_OPTIONAL_KERNEL_RWX || 1018 default !ARCH_OPTIONAL_KERNEL_RWX || ARCH_OPTIONAL_KERNEL_RWX_DEFAULT
1464 help 1019 help
1465 If this is set, module text and rod 1020 If this is set, module text and rodata memory will be made read-only,
1466 and non-text memory will be made no 1021 and non-text memory will be made non-executable. This provides
1467 protection against certain security 1022 protection against certain security exploits (e.g. writing to text)
1468 1023
1469 # select if the architecture provides an asm/ 1024 # select if the architecture provides an asm/dma-direct.h header
1470 config ARCH_HAS_PHYS_TO_DMA 1025 config ARCH_HAS_PHYS_TO_DMA
1471 bool 1026 bool
1472 1027
1473 config HAVE_ARCH_COMPILER_H 1028 config HAVE_ARCH_COMPILER_H
1474 bool 1029 bool
1475 help 1030 help
1476 An architecture can select this if 1031 An architecture can select this if it provides an
1477 asm/compiler.h header that should b 1032 asm/compiler.h header that should be included after
1478 linux/compiler-*.h in order to over 1033 linux/compiler-*.h in order to override macro definitions that those
1479 headers generally provide. 1034 headers generally provide.
1480 1035
1481 config HAVE_ARCH_PREL32_RELOCATIONS 1036 config HAVE_ARCH_PREL32_RELOCATIONS
1482 bool 1037 bool
1483 help 1038 help
1484 May be selected by an architecture 1039 May be selected by an architecture if it supports place-relative
1485 32-bit relocations, both in the too 1040 32-bit relocations, both in the toolchain and in the module loader,
1486 in which case relative references c 1041 in which case relative references can be used in special sections
1487 for PCI fixup, initcalls etc which 1042 for PCI fixup, initcalls etc which are only half the size on 64 bit
1488 architectures, and don't require ru 1043 architectures, and don't require runtime relocation on relocatable
1489 kernels. 1044 kernels.
1490 1045
1491 config ARCH_USE_MEMREMAP_PROT 1046 config ARCH_USE_MEMREMAP_PROT
1492 bool 1047 bool
1493 1048
1494 config LOCK_EVENT_COUNTS 1049 config LOCK_EVENT_COUNTS
1495 bool "Locking event counts collection 1050 bool "Locking event counts collection"
1496 depends on DEBUG_FS 1051 depends on DEBUG_FS
1497 help 1052 help
1498 Enable light-weight counting of var 1053 Enable light-weight counting of various locking related events
1499 in the system with minimal performa 1054 in the system with minimal performance impact. This reduces
1500 the chance of application behavior 1055 the chance of application behavior change because of timing
1501 differences. The counts are reporte 1056 differences. The counts are reported via debugfs.
1502 1057
1503 # Select if the architecture has support for 1058 # Select if the architecture has support for applying RELR relocations.
1504 config ARCH_HAS_RELR 1059 config ARCH_HAS_RELR
1505 bool 1060 bool
1506 1061
1507 config RELR 1062 config RELR
1508 bool "Use RELR relocation packing" 1063 bool "Use RELR relocation packing"
1509 depends on ARCH_HAS_RELR && TOOLS_SUP 1064 depends on ARCH_HAS_RELR && TOOLS_SUPPORT_RELR
1510 default y 1065 default y
1511 help 1066 help
1512 Store the kernel's dynamic relocati 1067 Store the kernel's dynamic relocations in the RELR relocation packing
1513 format. Requires a compatible linke 1068 format. Requires a compatible linker (LLD supports this feature), as
1514 well as compatible NM and OBJCOPY u 1069 well as compatible NM and OBJCOPY utilities (llvm-nm and llvm-objcopy
1515 are compatible). 1070 are compatible).
1516 1071
1517 config ARCH_HAS_MEM_ENCRYPT 1072 config ARCH_HAS_MEM_ENCRYPT
1518 bool 1073 bool
1519 1074
1520 config ARCH_HAS_CC_PLATFORM <<
1521 bool <<
1522 <<
1523 config HAVE_SPARSE_SYSCALL_NR 1075 config HAVE_SPARSE_SYSCALL_NR
1524 bool !! 1076 bool
1525 help !! 1077 help
1526 An architecture should select this !! 1078 An architecture should select this if its syscall numbering is sparse
1527 to save space. For example, MIPS ar 1079 to save space. For example, MIPS architecture has a syscall array with
1528 entries at 4000, 5000 and 6000 loca 1080 entries at 4000, 5000 and 6000 locations. This option turns on syscall
1529 related optimizations for a given a 1081 related optimizations for a given architecture.
1530 1082
1531 config ARCH_HAS_VDSO_DATA 1083 config ARCH_HAS_VDSO_DATA
1532 bool 1084 bool
1533 1085
1534 config HAVE_STATIC_CALL 1086 config HAVE_STATIC_CALL
1535 bool 1087 bool
1536 1088
1537 config HAVE_STATIC_CALL_INLINE 1089 config HAVE_STATIC_CALL_INLINE
1538 bool 1090 bool
1539 depends on HAVE_STATIC_CALL 1091 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 1092
1580 config ARCH_WANT_LD_ORPHAN_WARN 1093 config ARCH_WANT_LD_ORPHAN_WARN
1581 bool 1094 bool
1582 help 1095 help
1583 An arch should select this symbol o 1096 An arch should select this symbol once all linker sections are explicitly
1584 included, size-asserted, or discard 1097 included, size-asserted, or discarded in the linker scripts. This is
1585 important because we never want exp 1098 important because we never want expected sections to be placed heuristically
1586 by the linker, since the locations 1099 by the linker, since the locations of such sections can change between linker
1587 versions. 1100 versions.
1588 1101
1589 config HAVE_ARCH_PFN_VALID 1102 config HAVE_ARCH_PFN_VALID
1590 bool 1103 bool
1591 1104
1592 config ARCH_SUPPORTS_DEBUG_PAGEALLOC 1105 config ARCH_SUPPORTS_DEBUG_PAGEALLOC
1593 bool 1106 bool
1594 1107
1595 config ARCH_SUPPORTS_PAGE_TABLE_CHECK <<
1596 bool <<
1597 <<
1598 config ARCH_SPLIT_ARG64 1108 config ARCH_SPLIT_ARG64
1599 bool 1109 bool
1600 help 1110 help
1601 If a 32-bit architecture requires 6 !! 1111 If a 32-bit architecture requires 64-bit arguments to be split into
1602 pairs of 32-bit arguments, select t !! 1112 pairs of 32-bit arguments, select this option.
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 1113
1642 source "kernel/gcov/Kconfig" 1114 source "kernel/gcov/Kconfig"
1643 1115
1644 source "scripts/gcc-plugins/Kconfig" 1116 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 1117
1685 endmenu 1118 endmenu
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