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 <<
24 help <<
25 Select if the architecture can check <<
26 granularity (e.g. arm64 MTE). The pr <<
27 must be implemented. <<
28 <<
29 config HOTPLUG_SMT <<
30 bool <<
31 <<
32 config SMT_NUM_THREADS_DYNAMIC <<
33 bool 15 bool
34 16
35 # Selected by HOTPLUG_CORE_SYNC_DEAD or HOTPLU !! 17 config KEXEC_CORE
36 config HOTPLUG_CORE_SYNC !! 18 select CRASH_CORE
37 bool 19 bool
38 20
39 # Basic CPU dead synchronization selected by a !! 21 config KEXEC_ELF
40 config HOTPLUG_CORE_SYNC_DEAD <<
41 bool 22 bool
42 select HOTPLUG_CORE_SYNC <<
43 23
44 # Full CPU synchronization with alive state se !! 24 config HAVE_IMA_KEXEC
45 config HOTPLUG_CORE_SYNC_FULL <<
46 bool 25 bool
47 select HOTPLUG_CORE_SYNC_DEAD if HOTPL <<
48 select HOTPLUG_CORE_SYNC <<
49 26
50 config HOTPLUG_SPLIT_STARTUP !! 27 config SET_FS
51 bool 28 bool
52 select HOTPLUG_CORE_SYNC_FULL <<
53 29
54 config HOTPLUG_PARALLEL !! 30 config HOTPLUG_SMT
55 bool 31 bool
56 select HOTPLUG_SPLIT_STARTUP <<
57 32
58 config GENERIC_ENTRY 33 config GENERIC_ENTRY
59 bool !! 34 bool
60 35
61 config KPROBES 36 config KPROBES
62 bool "Kprobes" 37 bool "Kprobes"
>> 38 depends on MODULES
63 depends on HAVE_KPROBES 39 depends on HAVE_KPROBES
64 select KALLSYMS 40 select KALLSYMS
65 select EXECMEM <<
66 select NEED_TASKS_RCU <<
67 help 41 help
68 Kprobes allows you to trap at almost 42 Kprobes allows you to trap at almost any kernel address and
69 execute a callback function. regist 43 execute a callback function. register_kprobe() establishes
70 a probepoint and specifies the callb 44 a probepoint and specifies the callback. Kprobes is useful
71 for kernel debugging, non-intrusive 45 for kernel debugging, non-intrusive instrumentation and testing.
72 If in doubt, say "N". 46 If in doubt, say "N".
73 47
74 config JUMP_LABEL 48 config JUMP_LABEL
75 bool "Optimize very unlikely/likely br 49 bool "Optimize very unlikely/likely branches"
76 depends on HAVE_ARCH_JUMP_LABEL 50 depends on HAVE_ARCH_JUMP_LABEL
77 select OBJTOOL if HAVE_JUMP_LABEL_HACK !! 51 depends on CC_HAS_ASM_GOTO
78 help 52 help
79 This option enables a transparent br !! 53 This option enables a transparent branch optimization that
80 makes certain almost-always-true or !! 54 makes certain almost-always-true or almost-always-false branch
81 conditions even cheaper to execute w !! 55 conditions even cheaper to execute within the kernel.
82 !! 56
83 Certain performance-sensitive kernel !! 57 Certain performance-sensitive kernel code, such as trace points,
84 scheduler functionality, networking !! 58 scheduler functionality, networking code and KVM have such
85 branches and include support for thi !! 59 branches and include support for this optimization technique.
86 !! 60
87 If it is detected that the compiler !! 61 If it is detected that the compiler has support for "asm goto",
88 the kernel will compile such branche !! 62 the kernel will compile such branches with just a nop
89 instruction. When the condition flag !! 63 instruction. When the condition flag is toggled to true, the
90 nop will be converted to a jump inst !! 64 nop will be converted to a jump instruction to execute the
91 conditional block of instructions. !! 65 conditional block of instructions.
92 !! 66
93 This technique lowers overhead and s !! 67 This technique lowers overhead and stress on the branch prediction
94 of the processor and generally makes !! 68 of the processor and generally makes the kernel faster. The update
95 of the condition is slower, but thos !! 69 of the condition is slower, but those are always very rare.
96 70
97 ( On 32-bit x86, the necessary optio !! 71 ( On 32-bit x86, the necessary options added to the compiler
98 flags may increase the size of the !! 72 flags may increase the size of the kernel slightly. )
99 73
100 config STATIC_KEYS_SELFTEST 74 config STATIC_KEYS_SELFTEST
101 bool "Static key selftest" 75 bool "Static key selftest"
102 depends on JUMP_LABEL 76 depends on JUMP_LABEL
103 help 77 help
104 Boot time self-test of the branch pa 78 Boot time self-test of the branch patching code.
105 79
106 config STATIC_CALL_SELFTEST 80 config STATIC_CALL_SELFTEST
107 bool "Static call selftest" 81 bool "Static call selftest"
108 depends on HAVE_STATIC_CALL 82 depends on HAVE_STATIC_CALL
109 help 83 help
110 Boot time self-test of the call patc 84 Boot time self-test of the call patching code.
111 85
112 config OPTPROBES 86 config OPTPROBES
113 def_bool y 87 def_bool y
114 depends on KPROBES && HAVE_OPTPROBES 88 depends on KPROBES && HAVE_OPTPROBES
115 select NEED_TASKS_RCU !! 89 select TASKS_RCU if PREEMPTION
116 90
117 config KPROBES_ON_FTRACE 91 config KPROBES_ON_FTRACE
118 def_bool y 92 def_bool y
119 depends on KPROBES && HAVE_KPROBES_ON_ 93 depends on KPROBES && HAVE_KPROBES_ON_FTRACE
120 depends on DYNAMIC_FTRACE_WITH_REGS 94 depends on DYNAMIC_FTRACE_WITH_REGS
121 help 95 help
122 If function tracer is enabled and th !! 96 If function tracer is enabled and the arch supports full
123 passing of pt_regs to function traci !! 97 passing of pt_regs to function tracing, then kprobes can
124 optimize on top of function tracing. !! 98 optimize on top of function tracing.
125 99
126 config UPROBES 100 config UPROBES
127 def_bool n 101 def_bool n
128 depends on ARCH_SUPPORTS_UPROBES 102 depends on ARCH_SUPPORTS_UPROBES
129 help 103 help
130 Uprobes is the user-space counterpar 104 Uprobes is the user-space counterpart to kprobes: they
131 enable instrumentation applications 105 enable instrumentation applications (such as 'perf probe')
132 to establish unintrusive probes in u 106 to establish unintrusive probes in user-space binaries and
133 libraries, by executing handler func 107 libraries, by executing handler functions when the probes
134 are hit by user-space applications. 108 are hit by user-space applications.
135 109
136 ( These probes come in the form of s 110 ( These probes come in the form of single-byte breakpoints,
137 managed by the kernel and kept tra 111 managed by the kernel and kept transparent to the probed
138 application. ) 112 application. )
139 113
140 config HAVE_64BIT_ALIGNED_ACCESS 114 config HAVE_64BIT_ALIGNED_ACCESS
141 def_bool 64BIT && !HAVE_EFFICIENT_UNAL 115 def_bool 64BIT && !HAVE_EFFICIENT_UNALIGNED_ACCESS
142 help 116 help
143 Some architectures require 64 bit ac 117 Some architectures require 64 bit accesses to be 64 bit
144 aligned, which also requires structs 118 aligned, which also requires structs containing 64 bit values
145 to be 64 bit aligned too. This inclu 119 to be 64 bit aligned too. This includes some 32 bit
146 architectures which can do 64 bit ac 120 architectures which can do 64 bit accesses, as well as 64 bit
147 architectures without unaligned acce 121 architectures without unaligned access.
148 122
149 This symbol should be selected by an 123 This symbol should be selected by an architecture if 64 bit
150 accesses are required to be 64 bit a 124 accesses are required to be 64 bit aligned in this way even
151 though it is not a 64 bit architectu 125 though it is not a 64 bit architecture.
152 126
153 See Documentation/core-api/unaligned 127 See Documentation/core-api/unaligned-memory-access.rst for
154 more information on the topic of una 128 more information on the topic of unaligned memory accesses.
155 129
156 config HAVE_EFFICIENT_UNALIGNED_ACCESS 130 config HAVE_EFFICIENT_UNALIGNED_ACCESS
157 bool 131 bool
158 help 132 help
159 Some architectures are unable to per 133 Some architectures are unable to perform unaligned accesses
160 without the use of get_unaligned/put 134 without the use of get_unaligned/put_unaligned. Others are
161 unable to perform such accesses effi 135 unable to perform such accesses efficiently (e.g. trap on
162 unaligned access and require fixing 136 unaligned access and require fixing it up in the exception
163 handler.) 137 handler.)
164 138
165 This symbol should be selected by an 139 This symbol should be selected by an architecture if it can
166 perform unaligned accesses efficient 140 perform unaligned accesses efficiently to allow different
167 code paths to be selected for these 141 code paths to be selected for these cases. Some network
168 drivers, for example, could opt to n 142 drivers, for example, could opt to not fix up alignment
169 problems with received packets if do 143 problems with received packets if doing so would not help
170 much. 144 much.
171 145
172 See Documentation/core-api/unaligned 146 See Documentation/core-api/unaligned-memory-access.rst for more
173 information on the topic of unaligne 147 information on the topic of unaligned memory accesses.
174 148
175 config ARCH_USE_BUILTIN_BSWAP 149 config ARCH_USE_BUILTIN_BSWAP
176 bool 150 bool
177 help 151 help
178 Modern versions of GCC (since 4.4) h !! 152 Modern versions of GCC (since 4.4) have builtin functions
179 for handling byte-swapping. Using th !! 153 for handling byte-swapping. Using these, instead of the old
180 inline assembler that the architectu !! 154 inline assembler that the architecture code provides in the
181 __arch_bswapXX() macros, allows the !! 155 __arch_bswapXX() macros, allows the compiler to see what's
182 happening and offers more opportunit !! 156 happening and offers more opportunity for optimisation. In
183 particular, the compiler will be abl !! 157 particular, the compiler will be able to combine the byteswap
184 with a nearby load or store and use !! 158 with a nearby load or store and use load-and-swap or
185 store-and-swap instructions if the a !! 159 store-and-swap instructions if the architecture has them. It
186 should almost *never* result in code !! 160 should almost *never* result in code which is worse than the
187 hand-coded assembler in <asm/swab.h> !! 161 hand-coded assembler in <asm/swab.h>. But just in case it
188 does, the use of the builtins is opt !! 162 does, the use of the builtins is optional.
189 !! 163
190 Any architecture with load-and-swap !! 164 Any architecture with load-and-swap or store-and-swap
191 instructions should set this. And it !! 165 instructions should set this. And it shouldn't hurt to set it
192 on architectures that don't have suc !! 166 on architectures that don't have such instructions.
193 167
194 config KRETPROBES 168 config KRETPROBES
195 def_bool y 169 def_bool y
196 depends on KPROBES && (HAVE_KRETPROBES !! 170 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 <<
203 171
204 config USER_RETURN_NOTIFIER 172 config USER_RETURN_NOTIFIER
205 bool 173 bool
206 depends on HAVE_USER_RETURN_NOTIFIER 174 depends on HAVE_USER_RETURN_NOTIFIER
207 help 175 help
208 Provide a kernel-internal notificati 176 Provide a kernel-internal notification when a cpu is about to
209 switch to user mode. 177 switch to user mode.
210 178
211 config HAVE_IOREMAP_PROT 179 config HAVE_IOREMAP_PROT
212 bool 180 bool
213 181
214 config HAVE_KPROBES 182 config HAVE_KPROBES
215 bool 183 bool
216 184
217 config HAVE_KRETPROBES 185 config HAVE_KRETPROBES
218 bool 186 bool
219 187
220 config HAVE_OPTPROBES 188 config HAVE_OPTPROBES
221 bool 189 bool
222 190
223 config HAVE_KPROBES_ON_FTRACE 191 config HAVE_KPROBES_ON_FTRACE
224 bool 192 bool
225 193
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 194 config HAVE_FUNCTION_ERROR_INJECTION
235 bool 195 bool
236 196
237 config HAVE_NMI 197 config HAVE_NMI
238 bool 198 bool
239 199
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 # 200 #
250 # An arch should select this if it provides al 201 # An arch should select this if it provides all these things:
251 # 202 #
252 # task_pt_regs() in asm/process 203 # task_pt_regs() in asm/processor.h or asm/ptrace.h
253 # arch_has_single_step() if there is ha 204 # arch_has_single_step() if there is hardware single-step support
254 # arch_has_block_step() if there is ha 205 # arch_has_block_step() if there is hardware block-step support
255 # asm/syscall.h supplying asm- 206 # asm/syscall.h supplying asm-generic/syscall.h interface
256 # linux/regset.h user_regset in 207 # linux/regset.h user_regset interfaces
257 # CORE_DUMP_USE_REGSET #define'd in l 208 # CORE_DUMP_USE_REGSET #define'd in linux/elf.h
258 # TIF_SYSCALL_TRACE calls ptrace_r !! 209 # TIF_SYSCALL_TRACE calls tracehook_report_syscall_{entry,exit}
259 # TIF_NOTIFY_RESUME calls resume_u !! 210 # TIF_NOTIFY_RESUME calls tracehook_notify_resume()
>> 211 # signal delivery calls tracehook_signal_handler()
260 # 212 #
261 config HAVE_ARCH_TRACEHOOK 213 config HAVE_ARCH_TRACEHOOK
262 bool 214 bool
263 215
264 config HAVE_DMA_CONTIGUOUS 216 config HAVE_DMA_CONTIGUOUS
265 bool 217 bool
266 218
267 config GENERIC_SMP_IDLE_THREAD 219 config GENERIC_SMP_IDLE_THREAD
268 bool 220 bool
269 221
270 config GENERIC_IDLE_POLL_SETUP 222 config GENERIC_IDLE_POLL_SETUP
271 bool 223 bool
272 224
273 config ARCH_HAS_FORTIFY_SOURCE 225 config ARCH_HAS_FORTIFY_SOURCE
274 bool 226 bool
275 help 227 help
276 An architecture should select this w 228 An architecture should select this when it can successfully
277 build and run with CONFIG_FORTIFY_SO 229 build and run with CONFIG_FORTIFY_SOURCE.
278 230
279 # 231 #
280 # Select if the arch provides a historic keepi 232 # Select if the arch provides a historic keepinit alias for the retain_initrd
281 # command line option 233 # command line option
282 # 234 #
283 config ARCH_HAS_KEEPINITRD 235 config ARCH_HAS_KEEPINITRD
284 bool 236 bool
285 237
286 # Select if arch has all set_memory_ro/rw/x/nx 238 # Select if arch has all set_memory_ro/rw/x/nx() functions in asm/cacheflush.h
287 config ARCH_HAS_SET_MEMORY 239 config ARCH_HAS_SET_MEMORY
288 bool 240 bool
289 241
290 # Select if arch has all set_direct_map_invali 242 # Select if arch has all set_direct_map_invalid/default() functions
291 config ARCH_HAS_SET_DIRECT_MAP 243 config ARCH_HAS_SET_DIRECT_MAP
292 bool 244 bool
293 245
294 # 246 #
295 # Select if the architecture provides the arch 247 # Select if the architecture provides the arch_dma_set_uncached symbol to
296 # either provide an uncached segment alias for 248 # either provide an uncached segment alias for a DMA allocation, or
297 # to remap the page tables in place. 249 # to remap the page tables in place.
298 # 250 #
299 config ARCH_HAS_DMA_SET_UNCACHED 251 config ARCH_HAS_DMA_SET_UNCACHED
300 bool 252 bool
301 253
302 # 254 #
303 # Select if the architectures provides the arc 255 # Select if the architectures provides the arch_dma_clear_uncached symbol
304 # to undo an in-place page table remap for unc 256 # to undo an in-place page table remap for uncached access.
305 # 257 #
306 config ARCH_HAS_DMA_CLEAR_UNCACHED 258 config ARCH_HAS_DMA_CLEAR_UNCACHED
307 bool 259 bool
308 260
309 config ARCH_HAS_CPU_FINALIZE_INIT !! 261 # Select if arch init_task must go in the __init_task_data section
>> 262 config ARCH_TASK_STRUCT_ON_STACK
310 bool 263 bool
311 264
312 # The architecture has a per-task state that i !! 265 # Select if arch has its private alloc_task_struct() function
313 config ARCH_HAS_CPU_PASID !! 266 config ARCH_TASK_STRUCT_ALLOCATOR
314 bool 267 bool
315 select IOMMU_MM_DATA <<
316 268
317 config HAVE_ARCH_THREAD_STRUCT_WHITELIST 269 config HAVE_ARCH_THREAD_STRUCT_WHITELIST
318 bool 270 bool
>> 271 depends on !ARCH_TASK_STRUCT_ALLOCATOR
319 help 272 help
320 An architecture should select this t 273 An architecture should select this to provide hardened usercopy
321 knowledge about what region of the t 274 knowledge about what region of the thread_struct should be
322 whitelisted for copying to userspace 275 whitelisted for copying to userspace. Normally this is only the
323 FPU registers. Specifically, arch_th 276 FPU registers. Specifically, arch_thread_struct_whitelist()
324 should be implemented. Without this, 277 should be implemented. Without this, the entire thread_struct
325 field in task_struct will be left wh 278 field in task_struct will be left whitelisted.
326 279
327 # Select if arch wants to size task_struct dyn !! 280 # Select if arch has its private alloc_thread_stack() function
328 config ARCH_WANTS_DYNAMIC_TASK_STRUCT !! 281 config ARCH_THREAD_STACK_ALLOCATOR
329 bool 282 bool
330 283
331 config ARCH_WANTS_NO_INSTR !! 284 # Select if arch wants to size task_struct dynamically via arch_task_struct_size:
>> 285 config ARCH_WANTS_DYNAMIC_TASK_STRUCT
332 bool 286 bool
333 help <<
334 An architecture should select this i <<
335 functions to denote that the toolcha <<
336 functions and is required for correc <<
337 287
338 config ARCH_32BIT_OFF_T 288 config ARCH_32BIT_OFF_T
339 bool 289 bool
340 depends on !64BIT 290 depends on !64BIT
341 help 291 help
342 All new 32-bit architectures should 292 All new 32-bit architectures should have 64-bit off_t type on
343 userspace side which corresponds to 293 userspace side which corresponds to the loff_t kernel type. This
344 is the requirement for modern ABIs. 294 is the requirement for modern ABIs. Some existing architectures
345 still support 32-bit off_t. This opt 295 still support 32-bit off_t. This option is enabled for all such
346 architectures explicitly. 296 architectures explicitly.
347 297
348 # Selected by 64 bit architectures which have 298 # Selected by 64 bit architectures which have a 32 bit f_tinode in struct ustat
349 config ARCH_32BIT_USTAT_F_TINODE 299 config ARCH_32BIT_USTAT_F_TINODE
350 bool 300 bool
351 301
352 config HAVE_ASM_MODVERSIONS 302 config HAVE_ASM_MODVERSIONS
353 bool 303 bool
354 help 304 help
355 This symbol should be selected by an 305 This symbol should be selected by an architecture if it provides
356 <asm/asm-prototypes.h> to support th 306 <asm/asm-prototypes.h> to support the module versioning for symbols
357 exported from assembly code. 307 exported from assembly code.
358 308
359 config HAVE_REGS_AND_STACK_ACCESS_API 309 config HAVE_REGS_AND_STACK_ACCESS_API
360 bool 310 bool
361 help 311 help
362 This symbol should be selected by an 312 This symbol should be selected by an architecture if it supports
363 the API needed to access registers a 313 the API needed to access registers and stack entries from pt_regs,
364 declared in asm/ptrace.h 314 declared in asm/ptrace.h
365 For example the kprobes-based event 315 For example the kprobes-based event tracer needs this API.
366 316
367 config HAVE_RSEQ 317 config HAVE_RSEQ
368 bool 318 bool
369 depends on HAVE_REGS_AND_STACK_ACCESS_ 319 depends on HAVE_REGS_AND_STACK_ACCESS_API
370 help 320 help
371 This symbol should be selected by an 321 This symbol should be selected by an architecture if it
372 supports an implementation of restar 322 supports an implementation of restartable sequences.
373 323
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 324 config HAVE_FUNCTION_ARG_ACCESS_API
381 bool 325 bool
382 help 326 help
383 This symbol should be selected by an 327 This symbol should be selected by an architecture if it supports
384 the API needed to access function ar 328 the API needed to access function arguments from pt_regs,
385 declared in asm/ptrace.h 329 declared in asm/ptrace.h
386 330
387 config HAVE_HW_BREAKPOINT 331 config HAVE_HW_BREAKPOINT
388 bool 332 bool
389 depends on PERF_EVENTS 333 depends on PERF_EVENTS
390 334
391 config HAVE_MIXED_BREAKPOINTS_REGS 335 config HAVE_MIXED_BREAKPOINTS_REGS
392 bool 336 bool
393 depends on HAVE_HW_BREAKPOINT 337 depends on HAVE_HW_BREAKPOINT
394 help 338 help
395 Depending on the arch implementation 339 Depending on the arch implementation of hardware breakpoints,
396 some of them have separate registers 340 some of them have separate registers for data and instruction
397 breakpoints addresses, others have m 341 breakpoints addresses, others have mixed registers to store
398 them but define the access type in a 342 them but define the access type in a control register.
399 Select this option if your arch impl 343 Select this option if your arch implements breakpoints under the
400 latter fashion. 344 latter fashion.
401 345
402 config HAVE_USER_RETURN_NOTIFIER 346 config HAVE_USER_RETURN_NOTIFIER
403 bool 347 bool
404 348
405 config HAVE_PERF_EVENTS_NMI 349 config HAVE_PERF_EVENTS_NMI
406 bool 350 bool
407 help 351 help
408 System hardware can generate an NMI 352 System hardware can generate an NMI using the perf event
409 subsystem. Also has support for cal 353 subsystem. Also has support for calculating CPU cycle events
410 to determine how many clock cycles i 354 to determine how many clock cycles in a given period.
411 355
412 config HAVE_HARDLOCKUP_DETECTOR_PERF 356 config HAVE_HARDLOCKUP_DETECTOR_PERF
413 bool 357 bool
414 depends on HAVE_PERF_EVENTS_NMI 358 depends on HAVE_PERF_EVENTS_NMI
415 help 359 help
416 The arch chooses to use the generic 360 The arch chooses to use the generic perf-NMI-based hardlockup
417 detector. Must define HAVE_PERF_EVEN 361 detector. Must define HAVE_PERF_EVENTS_NMI.
418 362
419 config HAVE_HARDLOCKUP_DETECTOR_ARCH !! 363 config HAVE_NMI_WATCHDOG
>> 364 depends on HAVE_NMI
420 bool 365 bool
421 help 366 help
422 The arch provides its own hardlockup !! 367 The arch provides a low level NMI watchdog. It provides
423 of the generic ones. !! 368 asm/nmi.h, and defines its own arch_touch_nmi_watchdog().
424 369
425 It uses the same command line parame !! 370 config HAVE_HARDLOCKUP_DETECTOR_ARCH
426 as the generic hardlockup detectors. !! 371 bool
>> 372 select HAVE_NMI_WATCHDOG
>> 373 help
>> 374 The arch chooses to provide its own hardlockup detector, which is
>> 375 a superset of the HAVE_NMI_WATCHDOG. It also conforms to config
>> 376 interfaces and parameters provided by hardlockup detector subsystem.
427 377
428 config HAVE_PERF_REGS 378 config HAVE_PERF_REGS
429 bool 379 bool
430 help 380 help
431 Support selective register dumps for 381 Support selective register dumps for perf events. This includes
432 bit-mapping of each registers and a 382 bit-mapping of each registers and a unique architecture id.
433 383
434 config HAVE_PERF_USER_STACK_DUMP 384 config HAVE_PERF_USER_STACK_DUMP
435 bool 385 bool
436 help 386 help
437 Support user stack dumps for perf ev 387 Support user stack dumps for perf event samples. This needs
438 access to the user stack pointer whi 388 access to the user stack pointer which is not unified across
439 architectures. 389 architectures.
440 390
441 config HAVE_ARCH_JUMP_LABEL 391 config HAVE_ARCH_JUMP_LABEL
442 bool 392 bool
443 393
444 config HAVE_ARCH_JUMP_LABEL_RELATIVE 394 config HAVE_ARCH_JUMP_LABEL_RELATIVE
445 bool 395 bool
446 396
447 config MMU_GATHER_TABLE_FREE 397 config MMU_GATHER_TABLE_FREE
448 bool 398 bool
449 399
450 config MMU_GATHER_RCU_TABLE_FREE 400 config MMU_GATHER_RCU_TABLE_FREE
451 bool 401 bool
452 select MMU_GATHER_TABLE_FREE 402 select MMU_GATHER_TABLE_FREE
453 403
454 config MMU_GATHER_PAGE_SIZE 404 config MMU_GATHER_PAGE_SIZE
455 bool 405 bool
456 406
457 config MMU_GATHER_NO_RANGE 407 config MMU_GATHER_NO_RANGE
458 bool 408 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 <<
466 409
467 config MMU_GATHER_NO_GATHER 410 config MMU_GATHER_NO_GATHER
468 bool 411 bool
469 depends on MMU_GATHER_TABLE_FREE 412 depends on MMU_GATHER_TABLE_FREE
470 413
471 config ARCH_WANT_IRQS_OFF_ACTIVATE_MM 414 config ARCH_WANT_IRQS_OFF_ACTIVATE_MM
472 bool 415 bool
473 help 416 help
474 Temporary select until all architect 417 Temporary select until all architectures can be converted to have
475 irqs disabled over activate_mm. Arch 418 irqs disabled over activate_mm. Architectures that do IPI based TLB
476 shootdowns should enable this. 419 shootdowns should enable this.
477 420
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 421 config ARCH_HAVE_NMI_SAFE_CMPXCHG
511 bool 422 bool
512 423
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 424 config HAVE_ALIGNED_STRUCT_PAGE
526 bool 425 bool
527 help 426 help
528 This makes sure that struct pages ar 427 This makes sure that struct pages are double word aligned and that
529 e.g. the SLUB allocator can perform 428 e.g. the SLUB allocator can perform double word atomic operations
530 on a struct page for better performa 429 on a struct page for better performance. However selecting this
531 might increase the size of a struct 430 might increase the size of a struct page by a word.
532 431
533 config HAVE_CMPXCHG_LOCAL 432 config HAVE_CMPXCHG_LOCAL
534 bool 433 bool
535 434
536 config HAVE_CMPXCHG_DOUBLE 435 config HAVE_CMPXCHG_DOUBLE
537 bool 436 bool
538 437
539 config ARCH_WEAK_RELEASE_ACQUIRE 438 config ARCH_WEAK_RELEASE_ACQUIRE
540 bool 439 bool
541 440
542 config ARCH_WANT_IPC_PARSE_VERSION 441 config ARCH_WANT_IPC_PARSE_VERSION
543 bool 442 bool
544 443
545 config ARCH_WANT_COMPAT_IPC_PARSE_VERSION 444 config ARCH_WANT_COMPAT_IPC_PARSE_VERSION
546 bool 445 bool
547 446
548 config ARCH_WANT_OLD_COMPAT_IPC 447 config ARCH_WANT_OLD_COMPAT_IPC
549 select ARCH_WANT_COMPAT_IPC_PARSE_VERS 448 select ARCH_WANT_COMPAT_IPC_PARSE_VERSION
550 bool 449 bool
551 450
552 config HAVE_ARCH_SECCOMP 451 config HAVE_ARCH_SECCOMP
553 bool 452 bool
554 help 453 help
555 An arch should select this symbol to 454 An arch should select this symbol to support seccomp mode 1 (the fixed
556 syscall policy), and must provide an 455 syscall policy), and must provide an overrides for __NR_seccomp_sigreturn,
557 and compat syscalls if the asm-gener 456 and compat syscalls if the asm-generic/seccomp.h defaults need adjustment:
558 - __NR_seccomp_read_32 457 - __NR_seccomp_read_32
559 - __NR_seccomp_write_32 458 - __NR_seccomp_write_32
560 - __NR_seccomp_exit_32 459 - __NR_seccomp_exit_32
561 - __NR_seccomp_sigreturn_32 460 - __NR_seccomp_sigreturn_32
562 461
563 config HAVE_ARCH_SECCOMP_FILTER 462 config HAVE_ARCH_SECCOMP_FILTER
564 bool 463 bool
565 select HAVE_ARCH_SECCOMP 464 select HAVE_ARCH_SECCOMP
566 help 465 help
567 An arch should select this symbol if 466 An arch should select this symbol if it provides all of these things:
568 - all the requirements for HAVE_ARCH 467 - all the requirements for HAVE_ARCH_SECCOMP
569 - syscall_get_arch() 468 - syscall_get_arch()
570 - syscall_get_arguments() 469 - syscall_get_arguments()
571 - syscall_rollback() 470 - syscall_rollback()
572 - syscall_set_return_value() 471 - syscall_set_return_value()
573 - SIGSYS siginfo_t support 472 - SIGSYS siginfo_t support
574 - secure_computing is called from a 473 - secure_computing is called from a ptrace_event()-safe context
575 - secure_computing return value is c 474 - secure_computing return value is checked and a return value of -1
576 results in the system call being s 475 results in the system call being skipped immediately.
577 - seccomp syscall wired up 476 - seccomp syscall wired up
578 - if !HAVE_SPARSE_SYSCALL_NR, have S 477 - if !HAVE_SPARSE_SYSCALL_NR, have SECCOMP_ARCH_NATIVE,
579 SECCOMP_ARCH_NATIVE_NR, SECCOMP_AR 478 SECCOMP_ARCH_NATIVE_NR, SECCOMP_ARCH_NATIVE_NAME defined. If
580 COMPAT is supported, have the SECC 479 COMPAT is supported, have the SECCOMP_ARCH_COMPAT* defines too.
581 480
582 config SECCOMP 481 config SECCOMP
583 prompt "Enable seccomp to safely execu 482 prompt "Enable seccomp to safely execute untrusted bytecode"
584 def_bool y 483 def_bool y
585 depends on HAVE_ARCH_SECCOMP 484 depends on HAVE_ARCH_SECCOMP
586 help 485 help
587 This kernel feature is useful for nu 486 This kernel feature is useful for number crunching applications
588 that may need to handle untrusted by 487 that may need to handle untrusted bytecode during their
589 execution. By using pipes or other t 488 execution. By using pipes or other transports made available
590 to the process as file descriptors s 489 to the process as file descriptors supporting the read/write
591 syscalls, it's possible to isolate t 490 syscalls, it's possible to isolate those applications in their
592 own address space using seccomp. Onc 491 own address space using seccomp. Once seccomp is enabled via
593 prctl(PR_SET_SECCOMP) or the seccomp 492 prctl(PR_SET_SECCOMP) or the seccomp() syscall, it cannot be
594 disabled and the task is only allowe 493 disabled and the task is only allowed to execute a few safe
595 syscalls defined by each seccomp mod 494 syscalls defined by each seccomp mode.
596 495
597 If unsure, say Y. 496 If unsure, say Y.
598 497
599 config SECCOMP_FILTER 498 config SECCOMP_FILTER
600 def_bool y 499 def_bool y
601 depends on HAVE_ARCH_SECCOMP_FILTER && 500 depends on HAVE_ARCH_SECCOMP_FILTER && SECCOMP && NET
602 help 501 help
603 Enable tasks to build secure computi 502 Enable tasks to build secure computing environments defined
604 in terms of Berkeley Packet Filter p 503 in terms of Berkeley Packet Filter programs which implement
605 task-defined system call filtering p 504 task-defined system call filtering polices.
606 505
607 See Documentation/userspace-api/secc 506 See Documentation/userspace-api/seccomp_filter.rst for details.
608 507
609 config SECCOMP_CACHE_DEBUG 508 config SECCOMP_CACHE_DEBUG
610 bool "Show seccomp filter cache status 509 bool "Show seccomp filter cache status in /proc/pid/seccomp_cache"
611 depends on SECCOMP_FILTER && !HAVE_SPA 510 depends on SECCOMP_FILTER && !HAVE_SPARSE_SYSCALL_NR
612 depends on PROC_FS 511 depends on PROC_FS
613 help 512 help
614 This enables the /proc/pid/seccomp_c 513 This enables the /proc/pid/seccomp_cache interface to monitor
615 seccomp cache data. The file format 514 seccomp cache data. The file format is subject to change. Reading
616 the file requires CAP_SYS_ADMIN. 515 the file requires CAP_SYS_ADMIN.
617 516
618 This option is for debugging only. E 517 This option is for debugging only. Enabling presents the risk that
619 an adversary may be able to infer th 518 an adversary may be able to infer the seccomp filter logic.
620 519
621 If unsure, say N. 520 If unsure, say N.
622 521
623 config HAVE_ARCH_STACKLEAK 522 config HAVE_ARCH_STACKLEAK
624 bool 523 bool
625 help 524 help
626 An architecture should select this i 525 An architecture should select this if it has the code which
627 fills the used part of the kernel st 526 fills the used part of the kernel stack with the STACKLEAK_POISON
628 value before returning from system c 527 value before returning from system calls.
629 528
630 config HAVE_STACKPROTECTOR 529 config HAVE_STACKPROTECTOR
631 bool 530 bool
632 help 531 help
633 An arch should select this symbol if 532 An arch should select this symbol if:
634 - it has implemented a stack canary 533 - it has implemented a stack canary (e.g. __stack_chk_guard)
635 534
636 config STACKPROTECTOR 535 config STACKPROTECTOR
637 bool "Stack Protector buffer overflow 536 bool "Stack Protector buffer overflow detection"
638 depends on HAVE_STACKPROTECTOR 537 depends on HAVE_STACKPROTECTOR
639 depends on $(cc-option,-fstack-protect 538 depends on $(cc-option,-fstack-protector)
640 default y 539 default y
641 help 540 help
642 This option turns on the "stack-prot 541 This option turns on the "stack-protector" GCC feature. This
643 feature puts, at the beginning of fu 542 feature puts, at the beginning of functions, a canary value on
644 the stack just before the return add 543 the stack just before the return address, and validates
645 the value just before actually retur 544 the value just before actually returning. Stack based buffer
646 overflows (that need to overwrite th 545 overflows (that need to overwrite this return address) now also
647 overwrite the canary, which gets det 546 overwrite the canary, which gets detected and the attack is then
648 neutralized via a kernel panic. 547 neutralized via a kernel panic.
649 548
650 Functions will have the stack-protec 549 Functions will have the stack-protector canary logic added if they
651 have an 8-byte or larger character a 550 have an 8-byte or larger character array on the stack.
652 551
653 This feature requires gcc version 4. 552 This feature requires gcc version 4.2 or above, or a distribution
654 gcc with the feature backported ("-f 553 gcc with the feature backported ("-fstack-protector").
655 554
656 On an x86 "defconfig" build, this fe 555 On an x86 "defconfig" build, this feature adds canary checks to
657 about 3% of all kernel functions, wh 556 about 3% of all kernel functions, which increases kernel code size
658 by about 0.3%. 557 by about 0.3%.
659 558
660 config STACKPROTECTOR_STRONG 559 config STACKPROTECTOR_STRONG
661 bool "Strong Stack Protector" 560 bool "Strong Stack Protector"
662 depends on STACKPROTECTOR 561 depends on STACKPROTECTOR
663 depends on $(cc-option,-fstack-protect 562 depends on $(cc-option,-fstack-protector-strong)
664 default y 563 default y
665 help 564 help
666 Functions will have the stack-protec 565 Functions will have the stack-protector canary logic added in any
667 of the following conditions: 566 of the following conditions:
668 567
669 - local variable's address used as p 568 - local variable's address used as part of the right hand side of an
670 assignment or function argument 569 assignment or function argument
671 - local variable is an array (or uni 570 - local variable is an array (or union containing an array),
672 regardless of array type or length 571 regardless of array type or length
673 - uses register local variables 572 - uses register local variables
674 573
675 This feature requires gcc version 4. 574 This feature requires gcc version 4.9 or above, or a distribution
676 gcc with the feature backported ("-f 575 gcc with the feature backported ("-fstack-protector-strong").
677 576
678 On an x86 "defconfig" build, this fe 577 On an x86 "defconfig" build, this feature adds canary checks to
679 about 20% of all kernel functions, w 578 about 20% of all kernel functions, which increases the kernel code
680 size by about 2%. 579 size by about 2%.
681 580
682 config ARCH_SUPPORTS_SHADOW_CALL_STACK 581 config ARCH_SUPPORTS_SHADOW_CALL_STACK
683 bool 582 bool
684 help 583 help
685 An architecture should select this i !! 584 An architecture should select this if it supports Clang's Shadow
686 Shadow Call Stack and implements run !! 585 Call Stack and implements runtime support for shadow stack
687 switching. 586 switching.
688 587
689 config SHADOW_CALL_STACK 588 config SHADOW_CALL_STACK
690 bool "Shadow Call Stack" !! 589 bool "Clang Shadow Call Stack"
691 depends on ARCH_SUPPORTS_SHADOW_CALL_S !! 590 depends on CC_IS_CLANG && ARCH_SUPPORTS_SHADOW_CALL_STACK
692 depends on DYNAMIC_FTRACE_WITH_ARGS || !! 591 depends on DYNAMIC_FTRACE_WITH_REGS || !FUNCTION_GRAPH_TRACER
693 depends on MMU !! 592 help
694 help !! 593 This option enables Clang's Shadow Call Stack, which uses a
695 This option enables the compiler's S !! 594 shadow stack to protect function return addresses from being
696 uses a shadow stack to protect funct !! 595 overwritten by an attacker. More information can be found in
697 being overwritten by an attacker. Mo !! 596 Clang's documentation:
698 in the compiler's documentation: <<
699 597
700 - Clang: https://clang.llvm.org/docs !! 598 https://clang.llvm.org/docs/ShadowCallStack.html
701 - GCC: https://gcc.gnu.org/onlinedoc <<
702 599
703 Note that security guarantees in the 600 Note that security guarantees in the kernel differ from the
704 ones documented for user space. The 601 ones documented for user space. The kernel must store addresses
705 of shadow stacks in memory, which me 602 of shadow stacks in memory, which means an attacker capable of
706 reading and writing arbitrary memory 603 reading and writing arbitrary memory may be able to locate them
707 and hijack control flow by modifying 604 and hijack control flow by modifying the stacks.
708 605
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 606 config LTO
717 bool 607 bool
718 help 608 help
719 Selected if the kernel will be built 609 Selected if the kernel will be built using the compiler's LTO feature.
720 610
721 config LTO_CLANG 611 config LTO_CLANG
722 bool 612 bool
723 select LTO 613 select LTO
724 help 614 help
725 Selected if the kernel will be built 615 Selected if the kernel will be built using Clang's LTO feature.
726 616
727 config ARCH_SUPPORTS_LTO_CLANG 617 config ARCH_SUPPORTS_LTO_CLANG
728 bool 618 bool
729 help 619 help
730 An architecture should select this o 620 An architecture should select this option if it supports:
731 - compiling with Clang, 621 - compiling with Clang,
732 - compiling inline assembly with Cla 622 - compiling inline assembly with Clang's integrated assembler,
733 - and linking with LLD. 623 - and linking with LLD.
734 624
735 config ARCH_SUPPORTS_LTO_CLANG_THIN 625 config ARCH_SUPPORTS_LTO_CLANG_THIN
736 bool 626 bool
737 help 627 help
738 An architecture should select this o 628 An architecture should select this option if it can support Clang's
739 ThinLTO mode. 629 ThinLTO mode.
740 630
741 config HAS_LTO_CLANG 631 config HAS_LTO_CLANG
742 def_bool y 632 def_bool y
743 depends on CC_IS_CLANG && LD_IS_LLD && !! 633 # Clang >= 11: https://github.com/ClangBuiltLinux/linux/issues/510
>> 634 depends on CC_IS_CLANG && CLANG_VERSION >= 110000 && LD_IS_LLD
>> 635 depends on $(success,test $(LLVM_IAS) -eq 1)
744 depends on $(success,$(NM) --help | he 636 depends on $(success,$(NM) --help | head -n 1 | grep -qi llvm)
745 depends on $(success,$(AR) --help | he 637 depends on $(success,$(AR) --help | head -n 1 | grep -qi llvm)
746 depends on ARCH_SUPPORTS_LTO_CLANG 638 depends on ARCH_SUPPORTS_LTO_CLANG
747 depends on !FTRACE_MCOUNT_USE_RECORDMC 639 depends on !FTRACE_MCOUNT_USE_RECORDMCOUNT
748 # https://github.com/ClangBuiltLinux/l !! 640 depends on !KASAN || KASAN_HW_TAGS
749 depends on (!KASAN || KASAN_HW_TAGS || <<
750 depends on (!KCOV || CLANG_VERSION >= <<
751 depends on !GCOV_KERNEL 641 depends on !GCOV_KERNEL
752 help 642 help
753 The compiler and Kconfig options sup 643 The compiler and Kconfig options support building with Clang's
754 LTO. 644 LTO.
755 645
756 choice 646 choice
757 prompt "Link Time Optimization (LTO)" 647 prompt "Link Time Optimization (LTO)"
758 default LTO_NONE 648 default LTO_NONE
759 help 649 help
760 This option enables Link Time Optimi 650 This option enables Link Time Optimization (LTO), which allows the
761 compiler to optimize binaries global 651 compiler to optimize binaries globally.
762 652
763 If unsure, select LTO_NONE. Note tha 653 If unsure, select LTO_NONE. Note that LTO is very resource-intensive
764 so it's disabled by default. 654 so it's disabled by default.
765 655
766 config LTO_NONE 656 config LTO_NONE
767 bool "None" 657 bool "None"
768 help 658 help
769 Build the kernel normally, without L 659 Build the kernel normally, without Link Time Optimization (LTO).
770 660
771 config LTO_CLANG_FULL 661 config LTO_CLANG_FULL
772 bool "Clang Full LTO (EXPERIMENTAL)" 662 bool "Clang Full LTO (EXPERIMENTAL)"
773 depends on HAS_LTO_CLANG 663 depends on HAS_LTO_CLANG
774 depends on !COMPILE_TEST 664 depends on !COMPILE_TEST
775 select LTO_CLANG 665 select LTO_CLANG
776 help 666 help
777 This option enables Clang's full Lin !! 667 This option enables Clang's full Link Time Optimization (LTO), which
778 allows the compiler to optimize the !! 668 allows the compiler to optimize the kernel globally. If you enable
779 this option, the compiler generates !! 669 this option, the compiler generates LLVM bitcode instead of ELF
780 object files, and the actual compila !! 670 object files, and the actual compilation from bitcode happens at
781 the LTO link step, which may take se !! 671 the LTO link step, which may take several minutes depending on the
782 kernel configuration. More informati !! 672 kernel configuration. More information can be found from LLVM's
783 documentation: !! 673 documentation:
784 674
785 https://llvm.org/docs/LinkTimeOpti 675 https://llvm.org/docs/LinkTimeOptimization.html
786 676
787 During link time, this option can us 677 During link time, this option can use a large amount of RAM, and
788 may take much longer than the ThinLT 678 may take much longer than the ThinLTO option.
789 679
790 config LTO_CLANG_THIN 680 config LTO_CLANG_THIN
791 bool "Clang ThinLTO (EXPERIMENTAL)" 681 bool "Clang ThinLTO (EXPERIMENTAL)"
792 depends on HAS_LTO_CLANG && ARCH_SUPPO 682 depends on HAS_LTO_CLANG && ARCH_SUPPORTS_LTO_CLANG_THIN
793 select LTO_CLANG 683 select LTO_CLANG
794 help 684 help
795 This option enables Clang's ThinLTO, 685 This option enables Clang's ThinLTO, which allows for parallel
796 optimization and faster incremental 686 optimization and faster incremental compiles compared to the
797 CONFIG_LTO_CLANG_FULL option. More i 687 CONFIG_LTO_CLANG_FULL option. More information can be found
798 from Clang's documentation: 688 from Clang's documentation:
799 689
800 https://clang.llvm.org/docs/ThinLT 690 https://clang.llvm.org/docs/ThinLTO.html
801 691
802 If unsure, say Y. 692 If unsure, say Y.
803 endchoice 693 endchoice
804 694
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 695 config HAVE_ARCH_WITHIN_STACK_FRAMES
840 bool 696 bool
841 help 697 help
842 An architecture should select this i 698 An architecture should select this if it can walk the kernel stack
843 frames to determine if an object is 699 frames to determine if an object is part of either the arguments
844 or local variables (i.e. that it exc 700 or local variables (i.e. that it excludes saved return addresses,
845 and similar) by implementing an inli 701 and similar) by implementing an inline arch_within_stack_frames(),
846 which is used by CONFIG_HARDENED_USE 702 which is used by CONFIG_HARDENED_USERCOPY.
847 703
848 config HAVE_CONTEXT_TRACKING_USER !! 704 config HAVE_CONTEXT_TRACKING
849 bool 705 bool
850 help 706 help
851 Provide kernel/user boundaries probe 707 Provide kernel/user boundaries probes necessary for subsystems
852 that need it, such as userspace RCU 708 that need it, such as userspace RCU extended quiescent state.
853 Syscalls need to be wrapped inside u 709 Syscalls need to be wrapped inside user_exit()-user_enter(), either
854 optimized behind static key or throu 710 optimized behind static key or through the slow path using TIF_NOHZ
855 flag. Exceptions handlers must be wr 711 flag. Exceptions handlers must be wrapped as well. Irqs are already
856 protected inside ct_irq_enter/ct_irq !! 712 protected inside rcu_irq_enter/rcu_irq_exit() but preemption or signal
857 handling on irq exit still need to b 713 handling on irq exit still need to be protected.
858 714
859 config HAVE_CONTEXT_TRACKING_USER_OFFSTACK !! 715 config HAVE_CONTEXT_TRACKING_OFFSTACK
860 bool 716 bool
861 help 717 help
862 Architecture neither relies on excep 718 Architecture neither relies on exception_enter()/exception_exit()
863 nor on schedule_user(). Also preempt 719 nor on schedule_user(). Also preempt_schedule_notrace() and
864 preempt_schedule_irq() can't be call 720 preempt_schedule_irq() can't be called in a preemptible section
865 while context tracking is CONTEXT_US 721 while context tracking is CONTEXT_USER. This feature reflects a sane
866 entry implementation where the follo 722 entry implementation where the following requirements are met on
867 critical entry code, ie: before user 723 critical entry code, ie: before user_exit() or after user_enter():
868 724
869 - Critical entry code isn't preempti 725 - Critical entry code isn't preemptible (or better yet:
870 not interruptible). 726 not interruptible).
871 - No use of RCU read side critical s !! 727 - No use of RCU read side critical sections, unless rcu_nmi_enter()
872 got called. 728 got called.
873 - No use of instrumentation, unless 729 - No use of instrumentation, unless instrumentation_begin() got
874 called. 730 called.
875 731
876 config HAVE_TIF_NOHZ 732 config HAVE_TIF_NOHZ
877 bool 733 bool
878 help 734 help
879 Arch relies on TIF_NOHZ and syscall 735 Arch relies on TIF_NOHZ and syscall slow path to implement context
880 tracking calls to user_enter()/user_ 736 tracking calls to user_enter()/user_exit().
881 737
882 config HAVE_VIRT_CPU_ACCOUNTING 738 config HAVE_VIRT_CPU_ACCOUNTING
883 bool 739 bool
884 740
885 config HAVE_VIRT_CPU_ACCOUNTING_IDLE 741 config HAVE_VIRT_CPU_ACCOUNTING_IDLE
886 bool 742 bool
887 help 743 help
888 Architecture has its own way to acco 744 Architecture has its own way to account idle CPU time and therefore
889 doesn't implement vtime_account_idle 745 doesn't implement vtime_account_idle().
890 746
891 config ARCH_HAS_SCALED_CPUTIME 747 config ARCH_HAS_SCALED_CPUTIME
892 bool 748 bool
893 749
894 config HAVE_VIRT_CPU_ACCOUNTING_GEN 750 config HAVE_VIRT_CPU_ACCOUNTING_GEN
895 bool 751 bool
896 default y if 64BIT 752 default y if 64BIT
897 help 753 help
898 With VIRT_CPU_ACCOUNTING_GEN, cputim 754 With VIRT_CPU_ACCOUNTING_GEN, cputime_t becomes 64-bit.
899 Before enabling this option, arch co 755 Before enabling this option, arch code must be audited
900 to ensure there are no races in conc 756 to ensure there are no races in concurrent read/write of
901 cputime_t. For example, reading/writ 757 cputime_t. For example, reading/writing 64-bit cputime_t on
902 some 32-bit arches may require multi 758 some 32-bit arches may require multiple accesses, so proper
903 locking is needed to protect against 759 locking is needed to protect against concurrent accesses.
904 760
905 config HAVE_IRQ_TIME_ACCOUNTING 761 config HAVE_IRQ_TIME_ACCOUNTING
906 bool 762 bool
907 help 763 help
908 Archs need to ensure they use a high 764 Archs need to ensure they use a high enough resolution clock to
909 support irq time accounting and then 765 support irq time accounting and then call enable_sched_clock_irqtime().
910 766
911 config HAVE_MOVE_PUD 767 config HAVE_MOVE_PUD
912 bool 768 bool
913 help 769 help
914 Architectures that select this are a 770 Architectures that select this are able to move page tables at the
915 PUD level. If there are only 3 page 771 PUD level. If there are only 3 page table levels, the move effectively
916 happens at the PGD level. 772 happens at the PGD level.
917 773
918 config HAVE_MOVE_PMD 774 config HAVE_MOVE_PMD
919 bool 775 bool
920 help 776 help
921 Archs that select this are able to m 777 Archs that select this are able to move page tables at the PMD level.
922 778
923 config HAVE_ARCH_TRANSPARENT_HUGEPAGE 779 config HAVE_ARCH_TRANSPARENT_HUGEPAGE
924 bool 780 bool
925 781
926 config HAVE_ARCH_TRANSPARENT_HUGEPAGE_PUD 782 config HAVE_ARCH_TRANSPARENT_HUGEPAGE_PUD
927 bool 783 bool
928 784
929 config HAVE_ARCH_HUGE_VMAP 785 config HAVE_ARCH_HUGE_VMAP
930 bool 786 bool
931 787
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 788 config ARCH_WANT_HUGE_PMD_SHARE
942 bool 789 bool
943 790
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 791 config HAVE_ARCH_SOFT_DIRTY
953 bool 792 bool
954 793
955 config HAVE_MOD_ARCH_SPECIFIC 794 config HAVE_MOD_ARCH_SPECIFIC
956 bool 795 bool
957 help 796 help
958 The arch uses struct mod_arch_specif 797 The arch uses struct mod_arch_specific to store data. Many arches
959 just need a simple module loader wit 798 just need a simple module loader without arch specific data - those
960 should not enable this. 799 should not enable this.
961 800
962 config MODULES_USE_ELF_RELA 801 config MODULES_USE_ELF_RELA
963 bool 802 bool
964 help 803 help
965 Modules only use ELF RELA relocation 804 Modules only use ELF RELA relocations. Modules with ELF REL
966 relocations will give an error. 805 relocations will give an error.
967 806
968 config MODULES_USE_ELF_REL 807 config MODULES_USE_ELF_REL
969 bool 808 bool
970 help 809 help
971 Modules only use ELF REL relocations 810 Modules only use ELF REL relocations. Modules with ELF RELA
972 relocations will give an error. 811 relocations will give an error.
973 812
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 813 config HAVE_IRQ_EXIT_ON_IRQ_STACK
989 bool 814 bool
990 help 815 help
991 Architecture doesn't only execute th 816 Architecture doesn't only execute the irq handler on the irq stack
992 but also irq_exit(). This way we can 817 but also irq_exit(). This way we can process softirqs on this irq
993 stack instead of switching to a new 818 stack instead of switching to a new one when we call __do_softirq()
994 in the end of an hardirq. 819 in the end of an hardirq.
995 This spares a stack switch and impro 820 This spares a stack switch and improves cache usage on softirq
996 processing. 821 processing.
997 822
998 config HAVE_SOFTIRQ_ON_OWN_STACK 823 config HAVE_SOFTIRQ_ON_OWN_STACK
999 bool 824 bool
1000 help 825 help
1001 Architecture provides a function to 826 Architecture provides a function to run __do_softirq() on a
1002 separate stack. !! 827 seperate 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 828
1014 config PGTABLE_LEVELS 829 config PGTABLE_LEVELS
1015 int 830 int
1016 default 2 831 default 2
1017 832
1018 config ARCH_HAS_ELF_RANDOMIZE 833 config ARCH_HAS_ELF_RANDOMIZE
1019 bool 834 bool
1020 help 835 help
1021 An architecture supports choosing r 836 An architecture supports choosing randomized locations for
1022 stack, mmap, brk, and ET_DYN. Defin 837 stack, mmap, brk, and ET_DYN. Defined functions:
1023 - arch_mmap_rnd() 838 - arch_mmap_rnd()
1024 - arch_randomize_brk() 839 - arch_randomize_brk()
1025 840
1026 config HAVE_ARCH_MMAP_RND_BITS 841 config HAVE_ARCH_MMAP_RND_BITS
1027 bool 842 bool
1028 help 843 help
1029 An arch should select this symbol i 844 An arch should select this symbol if it supports setting a variable
1030 number of bits for use in establish 845 number of bits for use in establishing the base address for mmap
1031 allocations, has MMU enabled and pr 846 allocations, has MMU enabled and provides values for both:
1032 - ARCH_MMAP_RND_BITS_MIN 847 - ARCH_MMAP_RND_BITS_MIN
1033 - ARCH_MMAP_RND_BITS_MAX 848 - ARCH_MMAP_RND_BITS_MAX
1034 849
1035 config HAVE_EXIT_THREAD 850 config HAVE_EXIT_THREAD
1036 bool 851 bool
1037 help 852 help
1038 An architecture implements exit_thr 853 An architecture implements exit_thread.
1039 854
1040 config ARCH_MMAP_RND_BITS_MIN 855 config ARCH_MMAP_RND_BITS_MIN
1041 int 856 int
1042 857
1043 config ARCH_MMAP_RND_BITS_MAX 858 config ARCH_MMAP_RND_BITS_MAX
1044 int 859 int
1045 860
1046 config ARCH_MMAP_RND_BITS_DEFAULT 861 config ARCH_MMAP_RND_BITS_DEFAULT
1047 int 862 int
1048 863
1049 config ARCH_MMAP_RND_BITS 864 config ARCH_MMAP_RND_BITS
1050 int "Number of bits to use for ASLR o 865 int "Number of bits to use for ASLR of mmap base address" if EXPERT
1051 range ARCH_MMAP_RND_BITS_MIN ARCH_MMA 866 range ARCH_MMAP_RND_BITS_MIN ARCH_MMAP_RND_BITS_MAX
1052 default ARCH_MMAP_RND_BITS_DEFAULT if 867 default ARCH_MMAP_RND_BITS_DEFAULT if ARCH_MMAP_RND_BITS_DEFAULT
1053 default ARCH_MMAP_RND_BITS_MIN 868 default ARCH_MMAP_RND_BITS_MIN
1054 depends on HAVE_ARCH_MMAP_RND_BITS 869 depends on HAVE_ARCH_MMAP_RND_BITS
1055 help 870 help
1056 This value can be used to select th 871 This value can be used to select the number of bits to use to
1057 determine the random offset to the 872 determine the random offset to the base address of vma regions
1058 resulting from mmap allocations. Th 873 resulting from mmap allocations. This value will be bounded
1059 by the architecture's minimum and m 874 by the architecture's minimum and maximum supported values.
1060 875
1061 This value can be changed after boo 876 This value can be changed after boot using the
1062 /proc/sys/vm/mmap_rnd_bits tunable 877 /proc/sys/vm/mmap_rnd_bits tunable
1063 878
1064 config HAVE_ARCH_MMAP_RND_COMPAT_BITS 879 config HAVE_ARCH_MMAP_RND_COMPAT_BITS
1065 bool 880 bool
1066 help 881 help
1067 An arch should select this symbol i 882 An arch should select this symbol if it supports running applications
1068 in compatibility mode, supports set 883 in compatibility mode, supports setting a variable number of bits for
1069 use in establishing the base addres 884 use in establishing the base address for mmap allocations, has MMU
1070 enabled and provides values for bot 885 enabled and provides values for both:
1071 - ARCH_MMAP_RND_COMPAT_BITS_MIN 886 - ARCH_MMAP_RND_COMPAT_BITS_MIN
1072 - ARCH_MMAP_RND_COMPAT_BITS_MAX 887 - ARCH_MMAP_RND_COMPAT_BITS_MAX
1073 888
1074 config ARCH_MMAP_RND_COMPAT_BITS_MIN 889 config ARCH_MMAP_RND_COMPAT_BITS_MIN
1075 int 890 int
1076 891
1077 config ARCH_MMAP_RND_COMPAT_BITS_MAX 892 config ARCH_MMAP_RND_COMPAT_BITS_MAX
1078 int 893 int
1079 894
1080 config ARCH_MMAP_RND_COMPAT_BITS_DEFAULT 895 config ARCH_MMAP_RND_COMPAT_BITS_DEFAULT
1081 int 896 int
1082 897
1083 config ARCH_MMAP_RND_COMPAT_BITS 898 config ARCH_MMAP_RND_COMPAT_BITS
1084 int "Number of bits to use for ASLR o 899 int "Number of bits to use for ASLR of mmap base address for compatible applications" if EXPERT
1085 range ARCH_MMAP_RND_COMPAT_BITS_MIN A 900 range ARCH_MMAP_RND_COMPAT_BITS_MIN ARCH_MMAP_RND_COMPAT_BITS_MAX
1086 default ARCH_MMAP_RND_COMPAT_BITS_DEF 901 default ARCH_MMAP_RND_COMPAT_BITS_DEFAULT if ARCH_MMAP_RND_COMPAT_BITS_DEFAULT
1087 default ARCH_MMAP_RND_COMPAT_BITS_MIN 902 default ARCH_MMAP_RND_COMPAT_BITS_MIN
1088 depends on HAVE_ARCH_MMAP_RND_COMPAT_ 903 depends on HAVE_ARCH_MMAP_RND_COMPAT_BITS
1089 help 904 help
1090 This value can be used to select th 905 This value can be used to select the number of bits to use to
1091 determine the random offset to the 906 determine the random offset to the base address of vma regions
1092 resulting from mmap allocations for 907 resulting from mmap allocations for compatible applications This
1093 value will be bounded by the archit 908 value will be bounded by the architecture's minimum and maximum
1094 supported values. 909 supported values.
1095 910
1096 This value can be changed after boo 911 This value can be changed after boot using the
1097 /proc/sys/vm/mmap_rnd_compat_bits t 912 /proc/sys/vm/mmap_rnd_compat_bits tunable
1098 913
1099 config HAVE_ARCH_COMPAT_MMAP_BASES 914 config HAVE_ARCH_COMPAT_MMAP_BASES
1100 bool 915 bool
1101 help 916 help
1102 This allows 64bit applications to i 917 This allows 64bit applications to invoke 32-bit mmap() syscall
1103 and vice-versa 32-bit applications 918 and vice-versa 32-bit applications to call 64-bit mmap().
1104 Required for applications doing dif 919 Required for applications doing different bitness syscalls.
1105 920
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 921 # This allows to use a set of generic functions to determine mmap base
1208 # address by giving priority to top-down sche 922 # address by giving priority to top-down scheme only if the process
1209 # is not in legacy mode (compat task, unlimit 923 # is not in legacy mode (compat task, unlimited stack size or
1210 # sysctl_legacy_va_layout). 924 # sysctl_legacy_va_layout).
1211 # Architecture that selects this option can p 925 # Architecture that selects this option can provide its own version of:
1212 # - STACK_RND_MASK 926 # - STACK_RND_MASK
1213 config ARCH_WANT_DEFAULT_TOPDOWN_MMAP_LAYOUT 927 config ARCH_WANT_DEFAULT_TOPDOWN_MMAP_LAYOUT
1214 bool 928 bool
1215 depends on MMU 929 depends on MMU
1216 select ARCH_HAS_ELF_RANDOMIZE 930 select ARCH_HAS_ELF_RANDOMIZE
1217 931
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 932 config HAVE_STACK_VALIDATION
1235 bool 933 bool
1236 help 934 help
1237 Architecture supports objtool compi !! 935 Architecture supports the 'objtool check' host tool command, which
1238 validation. !! 936 performs compile-time stack metadata validation.
1239 937
1240 config HAVE_RELIABLE_STACKTRACE 938 config HAVE_RELIABLE_STACKTRACE
1241 bool 939 bool
1242 help 940 help
1243 Architecture has either save_stack_ 941 Architecture has either save_stack_trace_tsk_reliable() or
1244 arch_stack_walk_reliable() function 942 arch_stack_walk_reliable() function which only returns a stack trace
1245 if it can guarantee the trace is re 943 if it can guarantee the trace is reliable.
1246 944
1247 config HAVE_ARCH_HASH 945 config HAVE_ARCH_HASH
1248 bool 946 bool
1249 default n 947 default n
1250 help 948 help
1251 If this is set, the architecture pr 949 If this is set, the architecture provides an <asm/hash.h>
1252 file which provides platform-specif 950 file which provides platform-specific implementations of some
1253 functions in <linux/hash.h> or fs/n 951 functions in <linux/hash.h> or fs/namei.c.
1254 952
1255 config HAVE_ARCH_NVRAM_OPS 953 config HAVE_ARCH_NVRAM_OPS
1256 bool 954 bool
1257 955
1258 config ISA_BUS_API 956 config ISA_BUS_API
1259 def_bool ISA 957 def_bool ISA
1260 958
1261 # 959 #
1262 # ABI hall of shame 960 # ABI hall of shame
1263 # 961 #
1264 config CLONE_BACKWARDS 962 config CLONE_BACKWARDS
1265 bool 963 bool
1266 help 964 help
1267 Architecture has tls passed as the 965 Architecture has tls passed as the 4th argument of clone(2),
1268 not the 5th one. 966 not the 5th one.
1269 967
1270 config CLONE_BACKWARDS2 968 config CLONE_BACKWARDS2
1271 bool 969 bool
1272 help 970 help
1273 Architecture has the first two argu 971 Architecture has the first two arguments of clone(2) swapped.
1274 972
1275 config CLONE_BACKWARDS3 973 config CLONE_BACKWARDS3
1276 bool 974 bool
1277 help 975 help
1278 Architecture has tls passed as the 976 Architecture has tls passed as the 3rd argument of clone(2),
1279 not the 5th one. 977 not the 5th one.
1280 978
1281 config ODD_RT_SIGACTION 979 config ODD_RT_SIGACTION
1282 bool 980 bool
1283 help 981 help
1284 Architecture has unusual rt_sigacti 982 Architecture has unusual rt_sigaction(2) arguments
1285 983
1286 config OLD_SIGSUSPEND 984 config OLD_SIGSUSPEND
1287 bool 985 bool
1288 help 986 help
1289 Architecture has old sigsuspend(2) 987 Architecture has old sigsuspend(2) syscall, of one-argument variety
1290 988
1291 config OLD_SIGSUSPEND3 989 config OLD_SIGSUSPEND3
1292 bool 990 bool
1293 help 991 help
1294 Even weirder antique ABI - three-ar 992 Even weirder antique ABI - three-argument sigsuspend(2)
1295 993
1296 config OLD_SIGACTION 994 config OLD_SIGACTION
1297 bool 995 bool
1298 help 996 help
1299 Architecture has old sigaction(2) s 997 Architecture has old sigaction(2) syscall. Nope, not the same
1300 as OLD_SIGSUSPEND | OLD_SIGSUSPEND3 998 as OLD_SIGSUSPEND | OLD_SIGSUSPEND3 - alpha has sigsuspend(2),
1301 but fairly different variant of sig 999 but fairly different variant of sigaction(2), thanks to OSF/1
1302 compatibility... 1000 compatibility...
1303 1001
1304 config COMPAT_OLD_SIGACTION 1002 config COMPAT_OLD_SIGACTION
1305 bool 1003 bool
1306 1004
1307 config COMPAT_32BIT_TIME 1005 config COMPAT_32BIT_TIME
1308 bool "Provide system calls for 32-bit 1006 bool "Provide system calls for 32-bit time_t"
1309 default !64BIT || COMPAT 1007 default !64BIT || COMPAT
1310 help 1008 help
1311 This enables 32 bit time_t support 1009 This enables 32 bit time_t support in addition to 64 bit time_t support.
1312 This is relevant on all 32-bit arch 1010 This is relevant on all 32-bit architectures, and 64-bit architectures
1313 as part of compat syscall handling. 1011 as part of compat syscall handling.
1314 1012
1315 config ARCH_NO_PREEMPT 1013 config ARCH_NO_PREEMPT
1316 bool 1014 bool
1317 1015
1318 config ARCH_SUPPORTS_RT 1016 config ARCH_SUPPORTS_RT
1319 bool 1017 bool
1320 1018
1321 config CPU_NO_EFFICIENT_FFS 1019 config CPU_NO_EFFICIENT_FFS
1322 def_bool n 1020 def_bool n
1323 1021
1324 config HAVE_ARCH_VMAP_STACK 1022 config HAVE_ARCH_VMAP_STACK
1325 def_bool n 1023 def_bool n
1326 help 1024 help
1327 An arch should select this symbol i 1025 An arch should select this symbol if it can support kernel stacks
1328 in vmalloc space. This means: 1026 in vmalloc space. This means:
1329 1027
1330 - vmalloc space must be large enoug 1028 - vmalloc space must be large enough to hold many kernel stacks.
1331 This may rule out many 32-bit arc 1029 This may rule out many 32-bit architectures.
1332 1030
1333 - Stacks in vmalloc space need to w 1031 - Stacks in vmalloc space need to work reliably. For example, if
1334 vmap page tables are created on d 1032 vmap page tables are created on demand, either this mechanism
1335 needs to work while the stack poi 1033 needs to work while the stack points to a virtual address with
1336 unpopulated page tables or arch c 1034 unpopulated page tables or arch code (switch_to() and switch_mm(),
1337 most likely) needs to ensure that 1035 most likely) needs to ensure that the stack's page table entries
1338 are populated before running on a 1036 are populated before running on a possibly unpopulated stack.
1339 1037
1340 - If the stack overflows into a gua 1038 - If the stack overflows into a guard page, something reasonable
1341 should happen. The definition of 1039 should happen. The definition of "reasonable" is flexible, but
1342 instantly rebooting without loggi 1040 instantly rebooting without logging anything would be unfriendly.
1343 1041
1344 config VMAP_STACK 1042 config VMAP_STACK
1345 default y 1043 default y
1346 bool "Use a virtually-mapped stack" 1044 bool "Use a virtually-mapped stack"
1347 depends on HAVE_ARCH_VMAP_STACK 1045 depends on HAVE_ARCH_VMAP_STACK
1348 depends on !KASAN || KASAN_HW_TAGS || 1046 depends on !KASAN || KASAN_HW_TAGS || KASAN_VMALLOC
1349 help 1047 help
1350 Enable this if you want the use vir 1048 Enable this if you want the use virtually-mapped kernel stacks
1351 with guard pages. This causes kern 1049 with guard pages. This causes kernel stack overflows to be
1352 caught immediately rather than caus 1050 caught immediately rather than causing difficult-to-diagnose
1353 corruption. 1051 corruption.
1354 1052
1355 To use this with software KASAN mod 1053 To use this with software KASAN modes, the architecture must support
1356 backing virtual mappings with real 1054 backing virtual mappings with real shadow memory, and KASAN_VMALLOC
1357 must be enabled. 1055 must be enabled.
1358 1056
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 1057 config ARCH_OPTIONAL_KERNEL_RWX
1397 def_bool n 1058 def_bool n
1398 1059
1399 config ARCH_OPTIONAL_KERNEL_RWX_DEFAULT 1060 config ARCH_OPTIONAL_KERNEL_RWX_DEFAULT
1400 def_bool n 1061 def_bool n
1401 1062
1402 config ARCH_HAS_STRICT_KERNEL_RWX 1063 config ARCH_HAS_STRICT_KERNEL_RWX
1403 def_bool n 1064 def_bool n
1404 1065
1405 config STRICT_KERNEL_RWX 1066 config STRICT_KERNEL_RWX
1406 bool "Make kernel text and rodata rea 1067 bool "Make kernel text and rodata read-only" if ARCH_OPTIONAL_KERNEL_RWX
1407 depends on ARCH_HAS_STRICT_KERNEL_RWX 1068 depends on ARCH_HAS_STRICT_KERNEL_RWX
1408 default !ARCH_OPTIONAL_KERNEL_RWX || 1069 default !ARCH_OPTIONAL_KERNEL_RWX || ARCH_OPTIONAL_KERNEL_RWX_DEFAULT
1409 help 1070 help
1410 If this is set, kernel text and rod 1071 If this is set, kernel text and rodata memory will be made read-only,
1411 and non-text memory will be made no 1072 and non-text memory will be made non-executable. This provides
1412 protection against certain security 1073 protection against certain security exploits (e.g. executing the heap
1413 or modifying text) 1074 or modifying text)
1414 1075
1415 These features are considered stand 1076 These features are considered standard security practice these days.
1416 You should say Y here in almost all 1077 You should say Y here in almost all cases.
1417 1078
1418 config ARCH_HAS_STRICT_MODULE_RWX 1079 config ARCH_HAS_STRICT_MODULE_RWX
1419 def_bool n 1080 def_bool n
1420 1081
1421 config STRICT_MODULE_RWX 1082 config STRICT_MODULE_RWX
1422 bool "Set loadable kernel module data 1083 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 1084 depends on ARCH_HAS_STRICT_MODULE_RWX && MODULES
1424 default !ARCH_OPTIONAL_KERNEL_RWX || 1085 default !ARCH_OPTIONAL_KERNEL_RWX || ARCH_OPTIONAL_KERNEL_RWX_DEFAULT
1425 help 1086 help
1426 If this is set, module text and rod 1087 If this is set, module text and rodata memory will be made read-only,
1427 and non-text memory will be made no 1088 and non-text memory will be made non-executable. This provides
1428 protection against certain security 1089 protection against certain security exploits (e.g. writing to text)
1429 1090
1430 # select if the architecture provides an asm/ 1091 # select if the architecture provides an asm/dma-direct.h header
1431 config ARCH_HAS_PHYS_TO_DMA 1092 config ARCH_HAS_PHYS_TO_DMA
1432 bool 1093 bool
1433 1094
1434 config HAVE_ARCH_COMPILER_H 1095 config HAVE_ARCH_COMPILER_H
1435 bool 1096 bool
1436 help 1097 help
1437 An architecture can select this if 1098 An architecture can select this if it provides an
1438 asm/compiler.h header that should b 1099 asm/compiler.h header that should be included after
1439 linux/compiler-*.h in order to over 1100 linux/compiler-*.h in order to override macro definitions that those
1440 headers generally provide. 1101 headers generally provide.
1441 1102
1442 config HAVE_ARCH_PREL32_RELOCATIONS 1103 config HAVE_ARCH_PREL32_RELOCATIONS
1443 bool 1104 bool
1444 help 1105 help
1445 May be selected by an architecture 1106 May be selected by an architecture if it supports place-relative
1446 32-bit relocations, both in the too 1107 32-bit relocations, both in the toolchain and in the module loader,
1447 in which case relative references c 1108 in which case relative references can be used in special sections
1448 for PCI fixup, initcalls etc which 1109 for PCI fixup, initcalls etc which are only half the size on 64 bit
1449 architectures, and don't require ru 1110 architectures, and don't require runtime relocation on relocatable
1450 kernels. 1111 kernels.
1451 1112
1452 config ARCH_USE_MEMREMAP_PROT 1113 config ARCH_USE_MEMREMAP_PROT
1453 bool 1114 bool
1454 1115
1455 config LOCK_EVENT_COUNTS 1116 config LOCK_EVENT_COUNTS
1456 bool "Locking event counts collection 1117 bool "Locking event counts collection"
1457 depends on DEBUG_FS 1118 depends on DEBUG_FS
1458 help 1119 help
1459 Enable light-weight counting of var 1120 Enable light-weight counting of various locking related events
1460 in the system with minimal performa 1121 in the system with minimal performance impact. This reduces
1461 the chance of application behavior 1122 the chance of application behavior change because of timing
1462 differences. The counts are reporte 1123 differences. The counts are reported via debugfs.
1463 1124
1464 # Select if the architecture has support for 1125 # Select if the architecture has support for applying RELR relocations.
1465 config ARCH_HAS_RELR 1126 config ARCH_HAS_RELR
1466 bool 1127 bool
1467 1128
1468 config RELR 1129 config RELR
1469 bool "Use RELR relocation packing" 1130 bool "Use RELR relocation packing"
1470 depends on ARCH_HAS_RELR && TOOLS_SUP 1131 depends on ARCH_HAS_RELR && TOOLS_SUPPORT_RELR
1471 default y 1132 default y
1472 help 1133 help
1473 Store the kernel's dynamic relocati 1134 Store the kernel's dynamic relocations in the RELR relocation packing
1474 format. Requires a compatible linke 1135 format. Requires a compatible linker (LLD supports this feature), as
1475 well as compatible NM and OBJCOPY u 1136 well as compatible NM and OBJCOPY utilities (llvm-nm and llvm-objcopy
1476 are compatible). 1137 are compatible).
1477 1138
1478 config ARCH_HAS_MEM_ENCRYPT 1139 config ARCH_HAS_MEM_ENCRYPT
1479 bool 1140 bool
1480 1141
1481 config ARCH_HAS_CC_PLATFORM <<
1482 bool <<
1483 <<
1484 config HAVE_SPARSE_SYSCALL_NR 1142 config HAVE_SPARSE_SYSCALL_NR
1485 bool !! 1143 bool
1486 help !! 1144 help
1487 An architecture should select this !! 1145 An architecture should select this if its syscall numbering is sparse
1488 to save space. For example, MIPS ar 1146 to save space. For example, MIPS architecture has a syscall array with
1489 entries at 4000, 5000 and 6000 loca 1147 entries at 4000, 5000 and 6000 locations. This option turns on syscall
1490 related optimizations for a given a 1148 related optimizations for a given architecture.
1491 1149
1492 config ARCH_HAS_VDSO_DATA 1150 config ARCH_HAS_VDSO_DATA
1493 bool 1151 bool
1494 1152
1495 config HAVE_STATIC_CALL 1153 config HAVE_STATIC_CALL
1496 bool 1154 bool
1497 1155
1498 config HAVE_STATIC_CALL_INLINE 1156 config HAVE_STATIC_CALL_INLINE
1499 bool 1157 bool
1500 depends on HAVE_STATIC_CALL 1158 depends on HAVE_STATIC_CALL
1501 select OBJTOOL <<
1502 1159
1503 config HAVE_PREEMPT_DYNAMIC 1160 config HAVE_PREEMPT_DYNAMIC
1504 bool 1161 bool
1505 <<
1506 config HAVE_PREEMPT_DYNAMIC_CALL <<
1507 bool <<
1508 depends on HAVE_STATIC_CALL 1162 depends on HAVE_STATIC_CALL
1509 select HAVE_PREEMPT_DYNAMIC !! 1163 depends on GENERIC_ENTRY
1510 help 1164 help
1511 An architecture should select this !! 1165 Select this if the architecture support boot time preempt setting
1512 model being selected at boot time u !! 1166 on top of static calls. It is strongly advised to support inline
1513 !! 1167 static call to avoid any overhead.
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 1168
1541 config ARCH_WANT_LD_ORPHAN_WARN 1169 config ARCH_WANT_LD_ORPHAN_WARN
1542 bool 1170 bool
1543 help 1171 help
1544 An arch should select this symbol o 1172 An arch should select this symbol once all linker sections are explicitly
1545 included, size-asserted, or discard 1173 included, size-asserted, or discarded in the linker scripts. This is
1546 important because we never want exp 1174 important because we never want expected sections to be placed heuristically
1547 by the linker, since the locations 1175 by the linker, since the locations of such sections can change between linker
1548 versions. 1176 versions.
1549 1177
1550 config HAVE_ARCH_PFN_VALID 1178 config HAVE_ARCH_PFN_VALID
1551 bool 1179 bool
1552 1180
1553 config ARCH_SUPPORTS_DEBUG_PAGEALLOC 1181 config ARCH_SUPPORTS_DEBUG_PAGEALLOC
1554 bool 1182 bool
1555 1183
1556 config ARCH_SUPPORTS_PAGE_TABLE_CHECK <<
1557 bool <<
1558 <<
1559 config ARCH_SPLIT_ARG64 1184 config ARCH_SPLIT_ARG64
1560 bool 1185 bool
1561 help 1186 help
1562 If a 32-bit architecture requires 6 !! 1187 If a 32-bit architecture requires 64-bit arguments to be split into
1563 pairs of 32-bit arguments, select t !! 1188 pairs of 32-bit arguments, select this option.
1564 1189
1565 config ARCH_HAS_ELFCORE_COMPAT 1190 config ARCH_HAS_ELFCORE_COMPAT
1566 bool 1191 bool
1567 1192
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 <<
1603 source "kernel/gcov/Kconfig" 1193 source "kernel/gcov/Kconfig"
1604 1194
1605 source "scripts/gcc-plugins/Kconfig" 1195 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 1196
1646 endmenu 1197 endmenu
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