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 config ARCH_CONFIGURES_CPU_MITIGATIONS
13 bool 13 bool
14 14
15 if !ARCH_CONFIGURES_CPU_MITIGATIONS 15 if !ARCH_CONFIGURES_CPU_MITIGATIONS
16 config CPU_MITIGATIONS 16 config CPU_MITIGATIONS
17 def_bool y 17 def_bool y
18 endif 18 endif
19 19
20 # <<
21 # Selected by architectures that need custom D <<
22 # IOMMUs not handled by dma-iommu. Drivers mu <<
23 # <<
24 config ARCH_HAS_DMA_OPS <<
25 depends on HAS_DMA <<
26 select DMA_OPS_HELPERS <<
27 bool <<
28 <<
29 menu "General architecture-dependent options" 20 menu "General architecture-dependent options"
30 21
31 config ARCH_HAS_SUBPAGE_FAULTS !! 22 config CRASH_CORE
32 bool <<
33 help <<
34 Select if the architecture can check <<
35 granularity (e.g. arm64 MTE). The pr <<
36 must be implemented. <<
37 <<
38 config HOTPLUG_SMT <<
39 bool <<
40 <<
41 config SMT_NUM_THREADS_DYNAMIC <<
42 bool 23 bool
43 24
44 # Selected by HOTPLUG_CORE_SYNC_DEAD or HOTPLU !! 25 config KEXEC_CORE
45 config HOTPLUG_CORE_SYNC !! 26 select CRASH_CORE
46 bool 27 bool
47 28
48 # Basic CPU dead synchronization selected by a !! 29 config KEXEC_ELF
49 config HOTPLUG_CORE_SYNC_DEAD <<
50 bool 30 bool
51 select HOTPLUG_CORE_SYNC <<
52 31
53 # Full CPU synchronization with alive state se !! 32 config HAVE_IMA_KEXEC
54 config HOTPLUG_CORE_SYNC_FULL <<
55 bool 33 bool
56 select HOTPLUG_CORE_SYNC_DEAD if HOTPL <<
57 select HOTPLUG_CORE_SYNC <<
58 34
59 config HOTPLUG_SPLIT_STARTUP !! 35 config SET_FS
60 bool 36 bool
61 select HOTPLUG_CORE_SYNC_FULL <<
62 37
63 config HOTPLUG_PARALLEL !! 38 config HOTPLUG_SMT
64 bool 39 bool
65 select HOTPLUG_SPLIT_STARTUP <<
66 40
67 config GENERIC_ENTRY 41 config GENERIC_ENTRY
68 bool !! 42 bool
69 43
70 config KPROBES 44 config KPROBES
71 bool "Kprobes" 45 bool "Kprobes"
>> 46 depends on MODULES
72 depends on HAVE_KPROBES 47 depends on HAVE_KPROBES
73 select KALLSYMS 48 select KALLSYMS
74 select EXECMEM <<
75 select NEED_TASKS_RCU <<
76 help 49 help
77 Kprobes allows you to trap at almost 50 Kprobes allows you to trap at almost any kernel address and
78 execute a callback function. regist 51 execute a callback function. register_kprobe() establishes
79 a probepoint and specifies the callb 52 a probepoint and specifies the callback. Kprobes is useful
80 for kernel debugging, non-intrusive 53 for kernel debugging, non-intrusive instrumentation and testing.
81 If in doubt, say "N". 54 If in doubt, say "N".
82 55
83 config JUMP_LABEL 56 config JUMP_LABEL
84 bool "Optimize very unlikely/likely br 57 bool "Optimize very unlikely/likely branches"
85 depends on HAVE_ARCH_JUMP_LABEL 58 depends on HAVE_ARCH_JUMP_LABEL
86 select OBJTOOL if HAVE_JUMP_LABEL_HACK !! 59 depends on CC_HAS_ASM_GOTO
87 help 60 help
88 This option enables a transparent br !! 61 This option enables a transparent branch optimization that
89 makes certain almost-always-true or !! 62 makes certain almost-always-true or almost-always-false branch
90 conditions even cheaper to execute w !! 63 conditions even cheaper to execute within the kernel.
91 !! 64
92 Certain performance-sensitive kernel !! 65 Certain performance-sensitive kernel code, such as trace points,
93 scheduler functionality, networking !! 66 scheduler functionality, networking code and KVM have such
94 branches and include support for thi !! 67 branches and include support for this optimization technique.
95 !! 68
96 If it is detected that the compiler !! 69 If it is detected that the compiler has support for "asm goto",
97 the kernel will compile such branche !! 70 the kernel will compile such branches with just a nop
98 instruction. When the condition flag !! 71 instruction. When the condition flag is toggled to true, the
99 nop will be converted to a jump inst !! 72 nop will be converted to a jump instruction to execute the
100 conditional block of instructions. !! 73 conditional block of instructions.
101 !! 74
102 This technique lowers overhead and s !! 75 This technique lowers overhead and stress on the branch prediction
103 of the processor and generally makes !! 76 of the processor and generally makes the kernel faster. The update
104 of the condition is slower, but thos !! 77 of the condition is slower, but those are always very rare.
105 78
106 ( On 32-bit x86, the necessary optio !! 79 ( On 32-bit x86, the necessary options added to the compiler
107 flags may increase the size of the !! 80 flags may increase the size of the kernel slightly. )
108 81
109 config STATIC_KEYS_SELFTEST 82 config STATIC_KEYS_SELFTEST
110 bool "Static key selftest" 83 bool "Static key selftest"
111 depends on JUMP_LABEL 84 depends on JUMP_LABEL
112 help 85 help
113 Boot time self-test of the branch pa 86 Boot time self-test of the branch patching code.
114 87
115 config STATIC_CALL_SELFTEST 88 config STATIC_CALL_SELFTEST
116 bool "Static call selftest" 89 bool "Static call selftest"
117 depends on HAVE_STATIC_CALL 90 depends on HAVE_STATIC_CALL
118 help 91 help
119 Boot time self-test of the call patc 92 Boot time self-test of the call patching code.
120 93
121 config OPTPROBES 94 config OPTPROBES
122 def_bool y 95 def_bool y
123 depends on KPROBES && HAVE_OPTPROBES 96 depends on KPROBES && HAVE_OPTPROBES
124 select NEED_TASKS_RCU !! 97 select TASKS_RCU if PREEMPTION
125 98
126 config KPROBES_ON_FTRACE 99 config KPROBES_ON_FTRACE
127 def_bool y 100 def_bool y
128 depends on KPROBES && HAVE_KPROBES_ON_ 101 depends on KPROBES && HAVE_KPROBES_ON_FTRACE
129 depends on DYNAMIC_FTRACE_WITH_REGS 102 depends on DYNAMIC_FTRACE_WITH_REGS
130 help 103 help
131 If function tracer is enabled and th !! 104 If function tracer is enabled and the arch supports full
132 passing of pt_regs to function traci !! 105 passing of pt_regs to function tracing, then kprobes can
133 optimize on top of function tracing. !! 106 optimize on top of function tracing.
134 107
135 config UPROBES 108 config UPROBES
136 def_bool n 109 def_bool n
137 depends on ARCH_SUPPORTS_UPROBES 110 depends on ARCH_SUPPORTS_UPROBES
138 help 111 help
139 Uprobes is the user-space counterpar 112 Uprobes is the user-space counterpart to kprobes: they
140 enable instrumentation applications 113 enable instrumentation applications (such as 'perf probe')
141 to establish unintrusive probes in u 114 to establish unintrusive probes in user-space binaries and
142 libraries, by executing handler func 115 libraries, by executing handler functions when the probes
143 are hit by user-space applications. 116 are hit by user-space applications.
144 117
145 ( These probes come in the form of s 118 ( These probes come in the form of single-byte breakpoints,
146 managed by the kernel and kept tra 119 managed by the kernel and kept transparent to the probed
147 application. ) 120 application. )
148 121
149 config HAVE_64BIT_ALIGNED_ACCESS 122 config HAVE_64BIT_ALIGNED_ACCESS
150 def_bool 64BIT && !HAVE_EFFICIENT_UNAL 123 def_bool 64BIT && !HAVE_EFFICIENT_UNALIGNED_ACCESS
151 help 124 help
152 Some architectures require 64 bit ac 125 Some architectures require 64 bit accesses to be 64 bit
153 aligned, which also requires structs 126 aligned, which also requires structs containing 64 bit values
154 to be 64 bit aligned too. This inclu 127 to be 64 bit aligned too. This includes some 32 bit
155 architectures which can do 64 bit ac 128 architectures which can do 64 bit accesses, as well as 64 bit
156 architectures without unaligned acce 129 architectures without unaligned access.
157 130
158 This symbol should be selected by an 131 This symbol should be selected by an architecture if 64 bit
159 accesses are required to be 64 bit a 132 accesses are required to be 64 bit aligned in this way even
160 though it is not a 64 bit architectu 133 though it is not a 64 bit architecture.
161 134
162 See Documentation/core-api/unaligned 135 See Documentation/core-api/unaligned-memory-access.rst for
163 more information on the topic of una 136 more information on the topic of unaligned memory accesses.
164 137
165 config HAVE_EFFICIENT_UNALIGNED_ACCESS 138 config HAVE_EFFICIENT_UNALIGNED_ACCESS
166 bool 139 bool
167 help 140 help
168 Some architectures are unable to per 141 Some architectures are unable to perform unaligned accesses
169 without the use of get_unaligned/put 142 without the use of get_unaligned/put_unaligned. Others are
170 unable to perform such accesses effi 143 unable to perform such accesses efficiently (e.g. trap on
171 unaligned access and require fixing 144 unaligned access and require fixing it up in the exception
172 handler.) 145 handler.)
173 146
174 This symbol should be selected by an 147 This symbol should be selected by an architecture if it can
175 perform unaligned accesses efficient 148 perform unaligned accesses efficiently to allow different
176 code paths to be selected for these 149 code paths to be selected for these cases. Some network
177 drivers, for example, could opt to n 150 drivers, for example, could opt to not fix up alignment
178 problems with received packets if do 151 problems with received packets if doing so would not help
179 much. 152 much.
180 153
181 See Documentation/core-api/unaligned 154 See Documentation/core-api/unaligned-memory-access.rst for more
182 information on the topic of unaligne 155 information on the topic of unaligned memory accesses.
183 156
184 config ARCH_USE_BUILTIN_BSWAP 157 config ARCH_USE_BUILTIN_BSWAP
185 bool 158 bool
186 help 159 help
187 Modern versions of GCC (since 4.4) h !! 160 Modern versions of GCC (since 4.4) have builtin functions
188 for handling byte-swapping. Using th !! 161 for handling byte-swapping. Using these, instead of the old
189 inline assembler that the architectu !! 162 inline assembler that the architecture code provides in the
190 __arch_bswapXX() macros, allows the !! 163 __arch_bswapXX() macros, allows the compiler to see what's
191 happening and offers more opportunit !! 164 happening and offers more opportunity for optimisation. In
192 particular, the compiler will be abl !! 165 particular, the compiler will be able to combine the byteswap
193 with a nearby load or store and use !! 166 with a nearby load or store and use load-and-swap or
194 store-and-swap instructions if the a !! 167 store-and-swap instructions if the architecture has them. It
195 should almost *never* result in code !! 168 should almost *never* result in code which is worse than the
196 hand-coded assembler in <asm/swab.h> !! 169 hand-coded assembler in <asm/swab.h>. But just in case it
197 does, the use of the builtins is opt !! 170 does, the use of the builtins is optional.
198 !! 171
199 Any architecture with load-and-swap !! 172 Any architecture with load-and-swap or store-and-swap
200 instructions should set this. And it !! 173 instructions should set this. And it shouldn't hurt to set it
201 on architectures that don't have suc !! 174 on architectures that don't have such instructions.
202 175
203 config KRETPROBES 176 config KRETPROBES
204 def_bool y 177 def_bool y
205 depends on KPROBES && (HAVE_KRETPROBES !! 178 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 <<
212 179
213 config USER_RETURN_NOTIFIER 180 config USER_RETURN_NOTIFIER
214 bool 181 bool
215 depends on HAVE_USER_RETURN_NOTIFIER 182 depends on HAVE_USER_RETURN_NOTIFIER
216 help 183 help
217 Provide a kernel-internal notificati 184 Provide a kernel-internal notification when a cpu is about to
218 switch to user mode. 185 switch to user mode.
219 186
220 config HAVE_IOREMAP_PROT 187 config HAVE_IOREMAP_PROT
221 bool 188 bool
222 189
223 config HAVE_KPROBES 190 config HAVE_KPROBES
224 bool 191 bool
225 192
226 config HAVE_KRETPROBES 193 config HAVE_KRETPROBES
227 bool 194 bool
228 195
229 config HAVE_OPTPROBES 196 config HAVE_OPTPROBES
230 bool 197 bool
231 198
232 config HAVE_KPROBES_ON_FTRACE 199 config HAVE_KPROBES_ON_FTRACE
233 bool 200 bool
234 201
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 202 config HAVE_FUNCTION_ERROR_INJECTION
244 bool 203 bool
245 204
246 config HAVE_NMI 205 config HAVE_NMI
247 bool 206 bool
248 207
249 config HAVE_FUNCTION_DESCRIPTORS <<
250 bool <<
251 <<
252 config TRACE_IRQFLAGS_SUPPORT 208 config TRACE_IRQFLAGS_SUPPORT
253 bool 209 bool
254 210
255 config TRACE_IRQFLAGS_NMI_SUPPORT 211 config TRACE_IRQFLAGS_NMI_SUPPORT
256 bool 212 bool
257 213
258 # 214 #
259 # An arch should select this if it provides al 215 # An arch should select this if it provides all these things:
260 # 216 #
261 # task_pt_regs() in asm/process 217 # task_pt_regs() in asm/processor.h or asm/ptrace.h
262 # arch_has_single_step() if there is ha 218 # arch_has_single_step() if there is hardware single-step support
263 # arch_has_block_step() if there is ha 219 # arch_has_block_step() if there is hardware block-step support
264 # asm/syscall.h supplying asm- 220 # asm/syscall.h supplying asm-generic/syscall.h interface
265 # linux/regset.h user_regset in 221 # linux/regset.h user_regset interfaces
266 # CORE_DUMP_USE_REGSET #define'd in l 222 # CORE_DUMP_USE_REGSET #define'd in linux/elf.h
267 # TIF_SYSCALL_TRACE calls ptrace_r !! 223 # TIF_SYSCALL_TRACE calls tracehook_report_syscall_{entry,exit}
268 # TIF_NOTIFY_RESUME calls resume_u !! 224 # TIF_NOTIFY_RESUME calls tracehook_notify_resume()
>> 225 # signal delivery calls tracehook_signal_handler()
269 # 226 #
270 config HAVE_ARCH_TRACEHOOK 227 config HAVE_ARCH_TRACEHOOK
271 bool 228 bool
272 229
273 config HAVE_DMA_CONTIGUOUS 230 config HAVE_DMA_CONTIGUOUS
274 bool 231 bool
275 232
276 config GENERIC_SMP_IDLE_THREAD 233 config GENERIC_SMP_IDLE_THREAD
277 bool 234 bool
278 235
279 config GENERIC_IDLE_POLL_SETUP 236 config GENERIC_IDLE_POLL_SETUP
280 bool 237 bool
281 238
282 config ARCH_HAS_FORTIFY_SOURCE 239 config ARCH_HAS_FORTIFY_SOURCE
283 bool 240 bool
284 help 241 help
285 An architecture should select this w 242 An architecture should select this when it can successfully
286 build and run with CONFIG_FORTIFY_SO 243 build and run with CONFIG_FORTIFY_SOURCE.
287 244
288 # 245 #
289 # Select if the arch provides a historic keepi 246 # Select if the arch provides a historic keepinit alias for the retain_initrd
290 # command line option 247 # command line option
291 # 248 #
292 config ARCH_HAS_KEEPINITRD 249 config ARCH_HAS_KEEPINITRD
293 bool 250 bool
294 251
295 # Select if arch has all set_memory_ro/rw/x/nx 252 # Select if arch has all set_memory_ro/rw/x/nx() functions in asm/cacheflush.h
296 config ARCH_HAS_SET_MEMORY 253 config ARCH_HAS_SET_MEMORY
297 bool 254 bool
298 255
299 # Select if arch has all set_direct_map_invali 256 # Select if arch has all set_direct_map_invalid/default() functions
300 config ARCH_HAS_SET_DIRECT_MAP 257 config ARCH_HAS_SET_DIRECT_MAP
301 bool 258 bool
302 259
303 # 260 #
304 # Select if the architecture provides the arch 261 # Select if the architecture provides the arch_dma_set_uncached symbol to
305 # either provide an uncached segment alias for 262 # either provide an uncached segment alias for a DMA allocation, or
306 # to remap the page tables in place. 263 # to remap the page tables in place.
307 # 264 #
308 config ARCH_HAS_DMA_SET_UNCACHED 265 config ARCH_HAS_DMA_SET_UNCACHED
309 bool 266 bool
310 267
311 # 268 #
312 # Select if the architectures provides the arc 269 # Select if the architectures provides the arch_dma_clear_uncached symbol
313 # to undo an in-place page table remap for unc 270 # to undo an in-place page table remap for uncached access.
314 # 271 #
315 config ARCH_HAS_DMA_CLEAR_UNCACHED 272 config ARCH_HAS_DMA_CLEAR_UNCACHED
316 bool 273 bool
317 274
318 config ARCH_HAS_CPU_FINALIZE_INIT 275 config ARCH_HAS_CPU_FINALIZE_INIT
319 bool 276 bool
320 277
321 # The architecture has a per-task state that i !! 278 # Select if arch init_task must go in the __init_task_data section
322 config ARCH_HAS_CPU_PASID !! 279 config ARCH_TASK_STRUCT_ON_STACK
>> 280 bool
>> 281
>> 282 # Select if arch has its private alloc_task_struct() function
>> 283 config ARCH_TASK_STRUCT_ALLOCATOR
323 bool 284 bool
324 select IOMMU_MM_DATA <<
325 285
326 config HAVE_ARCH_THREAD_STRUCT_WHITELIST 286 config HAVE_ARCH_THREAD_STRUCT_WHITELIST
327 bool 287 bool
>> 288 depends on !ARCH_TASK_STRUCT_ALLOCATOR
328 help 289 help
329 An architecture should select this t 290 An architecture should select this to provide hardened usercopy
330 knowledge about what region of the t 291 knowledge about what region of the thread_struct should be
331 whitelisted for copying to userspace 292 whitelisted for copying to userspace. Normally this is only the
332 FPU registers. Specifically, arch_th 293 FPU registers. Specifically, arch_thread_struct_whitelist()
333 should be implemented. Without this, 294 should be implemented. Without this, the entire thread_struct
334 field in task_struct will be left wh 295 field in task_struct will be left whitelisted.
335 296
>> 297 # Select if arch has its private alloc_thread_stack() function
>> 298 config ARCH_THREAD_STACK_ALLOCATOR
>> 299 bool
>> 300
336 # Select if arch wants to size task_struct dyn 301 # Select if arch wants to size task_struct dynamically via arch_task_struct_size:
337 config ARCH_WANTS_DYNAMIC_TASK_STRUCT 302 config ARCH_WANTS_DYNAMIC_TASK_STRUCT
338 bool 303 bool
339 304
340 config ARCH_WANTS_NO_INSTR 305 config ARCH_WANTS_NO_INSTR
341 bool 306 bool
342 help 307 help
343 An architecture should select this i 308 An architecture should select this if the noinstr macro is being used on
344 functions to denote that the toolcha 309 functions to denote that the toolchain should avoid instrumenting such
345 functions and is required for correc 310 functions and is required for correctness.
346 311
347 config ARCH_32BIT_OFF_T 312 config ARCH_32BIT_OFF_T
348 bool 313 bool
349 depends on !64BIT 314 depends on !64BIT
350 help 315 help
351 All new 32-bit architectures should 316 All new 32-bit architectures should have 64-bit off_t type on
352 userspace side which corresponds to 317 userspace side which corresponds to the loff_t kernel type. This
353 is the requirement for modern ABIs. 318 is the requirement for modern ABIs. Some existing architectures
354 still support 32-bit off_t. This opt 319 still support 32-bit off_t. This option is enabled for all such
355 architectures explicitly. 320 architectures explicitly.
356 321
357 # Selected by 64 bit architectures which have 322 # Selected by 64 bit architectures which have a 32 bit f_tinode in struct ustat
358 config ARCH_32BIT_USTAT_F_TINODE 323 config ARCH_32BIT_USTAT_F_TINODE
359 bool 324 bool
360 325
361 config HAVE_ASM_MODVERSIONS 326 config HAVE_ASM_MODVERSIONS
362 bool 327 bool
363 help 328 help
364 This symbol should be selected by an 329 This symbol should be selected by an architecture if it provides
365 <asm/asm-prototypes.h> to support th 330 <asm/asm-prototypes.h> to support the module versioning for symbols
366 exported from assembly code. 331 exported from assembly code.
367 332
368 config HAVE_REGS_AND_STACK_ACCESS_API 333 config HAVE_REGS_AND_STACK_ACCESS_API
369 bool 334 bool
370 help 335 help
371 This symbol should be selected by an 336 This symbol should be selected by an architecture if it supports
372 the API needed to access registers a 337 the API needed to access registers and stack entries from pt_regs,
373 declared in asm/ptrace.h 338 declared in asm/ptrace.h
374 For example the kprobes-based event 339 For example the kprobes-based event tracer needs this API.
375 340
376 config HAVE_RSEQ 341 config HAVE_RSEQ
377 bool 342 bool
378 depends on HAVE_REGS_AND_STACK_ACCESS_ 343 depends on HAVE_REGS_AND_STACK_ACCESS_API
379 help 344 help
380 This symbol should be selected by an 345 This symbol should be selected by an architecture if it
381 supports an implementation of restar 346 supports an implementation of restartable sequences.
382 347
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 348 config HAVE_FUNCTION_ARG_ACCESS_API
390 bool 349 bool
391 help 350 help
392 This symbol should be selected by an 351 This symbol should be selected by an architecture if it supports
393 the API needed to access function ar 352 the API needed to access function arguments from pt_regs,
394 declared in asm/ptrace.h 353 declared in asm/ptrace.h
395 354
396 config HAVE_HW_BREAKPOINT 355 config HAVE_HW_BREAKPOINT
397 bool 356 bool
398 depends on PERF_EVENTS 357 depends on PERF_EVENTS
399 358
400 config HAVE_MIXED_BREAKPOINTS_REGS 359 config HAVE_MIXED_BREAKPOINTS_REGS
401 bool 360 bool
402 depends on HAVE_HW_BREAKPOINT 361 depends on HAVE_HW_BREAKPOINT
403 help 362 help
404 Depending on the arch implementation 363 Depending on the arch implementation of hardware breakpoints,
405 some of them have separate registers 364 some of them have separate registers for data and instruction
406 breakpoints addresses, others have m 365 breakpoints addresses, others have mixed registers to store
407 them but define the access type in a 366 them but define the access type in a control register.
408 Select this option if your arch impl 367 Select this option if your arch implements breakpoints under the
409 latter fashion. 368 latter fashion.
410 369
411 config HAVE_USER_RETURN_NOTIFIER 370 config HAVE_USER_RETURN_NOTIFIER
412 bool 371 bool
413 372
414 config HAVE_PERF_EVENTS_NMI 373 config HAVE_PERF_EVENTS_NMI
415 bool 374 bool
416 help 375 help
417 System hardware can generate an NMI 376 System hardware can generate an NMI using the perf event
418 subsystem. Also has support for cal 377 subsystem. Also has support for calculating CPU cycle events
419 to determine how many clock cycles i 378 to determine how many clock cycles in a given period.
420 379
421 config HAVE_HARDLOCKUP_DETECTOR_PERF 380 config HAVE_HARDLOCKUP_DETECTOR_PERF
422 bool 381 bool
423 depends on HAVE_PERF_EVENTS_NMI 382 depends on HAVE_PERF_EVENTS_NMI
424 help 383 help
425 The arch chooses to use the generic 384 The arch chooses to use the generic perf-NMI-based hardlockup
426 detector. Must define HAVE_PERF_EVEN 385 detector. Must define HAVE_PERF_EVENTS_NMI.
427 386
428 config HAVE_HARDLOCKUP_DETECTOR_ARCH !! 387 config HAVE_NMI_WATCHDOG
>> 388 depends on HAVE_NMI
429 bool 389 bool
430 help 390 help
431 The arch provides its own hardlockup !! 391 The arch provides a low level NMI watchdog. It provides
432 of the generic ones. !! 392 asm/nmi.h, and defines its own arch_touch_nmi_watchdog().
433 393
434 It uses the same command line parame !! 394 config HAVE_HARDLOCKUP_DETECTOR_ARCH
435 as the generic hardlockup detectors. !! 395 bool
>> 396 select HAVE_NMI_WATCHDOG
>> 397 help
>> 398 The arch chooses to provide its own hardlockup detector, which is
>> 399 a superset of the HAVE_NMI_WATCHDOG. It also conforms to config
>> 400 interfaces and parameters provided by hardlockup detector subsystem.
436 401
437 config HAVE_PERF_REGS 402 config HAVE_PERF_REGS
438 bool 403 bool
439 help 404 help
440 Support selective register dumps for 405 Support selective register dumps for perf events. This includes
441 bit-mapping of each registers and a 406 bit-mapping of each registers and a unique architecture id.
442 407
443 config HAVE_PERF_USER_STACK_DUMP 408 config HAVE_PERF_USER_STACK_DUMP
444 bool 409 bool
445 help 410 help
446 Support user stack dumps for perf ev 411 Support user stack dumps for perf event samples. This needs
447 access to the user stack pointer whi 412 access to the user stack pointer which is not unified across
448 architectures. 413 architectures.
449 414
450 config HAVE_ARCH_JUMP_LABEL 415 config HAVE_ARCH_JUMP_LABEL
451 bool 416 bool
452 417
453 config HAVE_ARCH_JUMP_LABEL_RELATIVE 418 config HAVE_ARCH_JUMP_LABEL_RELATIVE
454 bool 419 bool
455 420
456 config MMU_GATHER_TABLE_FREE 421 config MMU_GATHER_TABLE_FREE
457 bool 422 bool
458 423
459 config MMU_GATHER_RCU_TABLE_FREE 424 config MMU_GATHER_RCU_TABLE_FREE
460 bool 425 bool
461 select MMU_GATHER_TABLE_FREE 426 select MMU_GATHER_TABLE_FREE
462 427
463 config MMU_GATHER_PAGE_SIZE 428 config MMU_GATHER_PAGE_SIZE
464 bool 429 bool
465 430
466 config MMU_GATHER_NO_RANGE 431 config MMU_GATHER_NO_RANGE
467 bool 432 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 <<
475 433
476 config MMU_GATHER_NO_GATHER 434 config MMU_GATHER_NO_GATHER
477 bool 435 bool
478 depends on MMU_GATHER_TABLE_FREE 436 depends on MMU_GATHER_TABLE_FREE
479 437
480 config ARCH_WANT_IRQS_OFF_ACTIVATE_MM 438 config ARCH_WANT_IRQS_OFF_ACTIVATE_MM
481 bool 439 bool
482 help 440 help
483 Temporary select until all architect 441 Temporary select until all architectures can be converted to have
484 irqs disabled over activate_mm. Arch 442 irqs disabled over activate_mm. Architectures that do IPI based TLB
485 shootdowns should enable this. 443 shootdowns should enable this.
486 444
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 445 config ARCH_HAVE_NMI_SAFE_CMPXCHG
520 bool 446 bool
521 447
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 448 config HAVE_ALIGNED_STRUCT_PAGE
535 bool 449 bool
536 help 450 help
537 This makes sure that struct pages ar 451 This makes sure that struct pages are double word aligned and that
538 e.g. the SLUB allocator can perform 452 e.g. the SLUB allocator can perform double word atomic operations
539 on a struct page for better performa 453 on a struct page for better performance. However selecting this
540 might increase the size of a struct 454 might increase the size of a struct page by a word.
541 455
542 config HAVE_CMPXCHG_LOCAL 456 config HAVE_CMPXCHG_LOCAL
543 bool 457 bool
544 458
545 config HAVE_CMPXCHG_DOUBLE 459 config HAVE_CMPXCHG_DOUBLE
546 bool 460 bool
547 461
548 config ARCH_WEAK_RELEASE_ACQUIRE 462 config ARCH_WEAK_RELEASE_ACQUIRE
549 bool 463 bool
550 464
551 config ARCH_WANT_IPC_PARSE_VERSION 465 config ARCH_WANT_IPC_PARSE_VERSION
552 bool 466 bool
553 467
554 config ARCH_WANT_COMPAT_IPC_PARSE_VERSION 468 config ARCH_WANT_COMPAT_IPC_PARSE_VERSION
555 bool 469 bool
556 470
557 config ARCH_WANT_OLD_COMPAT_IPC 471 config ARCH_WANT_OLD_COMPAT_IPC
558 select ARCH_WANT_COMPAT_IPC_PARSE_VERS 472 select ARCH_WANT_COMPAT_IPC_PARSE_VERSION
559 bool 473 bool
560 474
561 config HAVE_ARCH_SECCOMP 475 config HAVE_ARCH_SECCOMP
562 bool 476 bool
563 help 477 help
564 An arch should select this symbol to 478 An arch should select this symbol to support seccomp mode 1 (the fixed
565 syscall policy), and must provide an 479 syscall policy), and must provide an overrides for __NR_seccomp_sigreturn,
566 and compat syscalls if the asm-gener 480 and compat syscalls if the asm-generic/seccomp.h defaults need adjustment:
567 - __NR_seccomp_read_32 481 - __NR_seccomp_read_32
568 - __NR_seccomp_write_32 482 - __NR_seccomp_write_32
569 - __NR_seccomp_exit_32 483 - __NR_seccomp_exit_32
570 - __NR_seccomp_sigreturn_32 484 - __NR_seccomp_sigreturn_32
571 485
572 config HAVE_ARCH_SECCOMP_FILTER 486 config HAVE_ARCH_SECCOMP_FILTER
573 bool 487 bool
574 select HAVE_ARCH_SECCOMP 488 select HAVE_ARCH_SECCOMP
575 help 489 help
576 An arch should select this symbol if 490 An arch should select this symbol if it provides all of these things:
577 - all the requirements for HAVE_ARCH 491 - all the requirements for HAVE_ARCH_SECCOMP
578 - syscall_get_arch() 492 - syscall_get_arch()
579 - syscall_get_arguments() 493 - syscall_get_arguments()
580 - syscall_rollback() 494 - syscall_rollback()
581 - syscall_set_return_value() 495 - syscall_set_return_value()
582 - SIGSYS siginfo_t support 496 - SIGSYS siginfo_t support
583 - secure_computing is called from a 497 - secure_computing is called from a ptrace_event()-safe context
584 - secure_computing return value is c 498 - secure_computing return value is checked and a return value of -1
585 results in the system call being s 499 results in the system call being skipped immediately.
586 - seccomp syscall wired up 500 - seccomp syscall wired up
587 - if !HAVE_SPARSE_SYSCALL_NR, have S 501 - if !HAVE_SPARSE_SYSCALL_NR, have SECCOMP_ARCH_NATIVE,
588 SECCOMP_ARCH_NATIVE_NR, SECCOMP_AR 502 SECCOMP_ARCH_NATIVE_NR, SECCOMP_ARCH_NATIVE_NAME defined. If
589 COMPAT is supported, have the SECC 503 COMPAT is supported, have the SECCOMP_ARCH_COMPAT* defines too.
590 504
591 config SECCOMP 505 config SECCOMP
592 prompt "Enable seccomp to safely execu 506 prompt "Enable seccomp to safely execute untrusted bytecode"
593 def_bool y 507 def_bool y
594 depends on HAVE_ARCH_SECCOMP 508 depends on HAVE_ARCH_SECCOMP
595 help 509 help
596 This kernel feature is useful for nu 510 This kernel feature is useful for number crunching applications
597 that may need to handle untrusted by 511 that may need to handle untrusted bytecode during their
598 execution. By using pipes or other t 512 execution. By using pipes or other transports made available
599 to the process as file descriptors s 513 to the process as file descriptors supporting the read/write
600 syscalls, it's possible to isolate t 514 syscalls, it's possible to isolate those applications in their
601 own address space using seccomp. Onc 515 own address space using seccomp. Once seccomp is enabled via
602 prctl(PR_SET_SECCOMP) or the seccomp 516 prctl(PR_SET_SECCOMP) or the seccomp() syscall, it cannot be
603 disabled and the task is only allowe 517 disabled and the task is only allowed to execute a few safe
604 syscalls defined by each seccomp mod 518 syscalls defined by each seccomp mode.
605 519
606 If unsure, say Y. 520 If unsure, say Y.
607 521
608 config SECCOMP_FILTER 522 config SECCOMP_FILTER
609 def_bool y 523 def_bool y
610 depends on HAVE_ARCH_SECCOMP_FILTER && 524 depends on HAVE_ARCH_SECCOMP_FILTER && SECCOMP && NET
611 help 525 help
612 Enable tasks to build secure computi 526 Enable tasks to build secure computing environments defined
613 in terms of Berkeley Packet Filter p 527 in terms of Berkeley Packet Filter programs which implement
614 task-defined system call filtering p 528 task-defined system call filtering polices.
615 529
616 See Documentation/userspace-api/secc 530 See Documentation/userspace-api/seccomp_filter.rst for details.
617 531
618 config SECCOMP_CACHE_DEBUG 532 config SECCOMP_CACHE_DEBUG
619 bool "Show seccomp filter cache status 533 bool "Show seccomp filter cache status in /proc/pid/seccomp_cache"
620 depends on SECCOMP_FILTER && !HAVE_SPA 534 depends on SECCOMP_FILTER && !HAVE_SPARSE_SYSCALL_NR
621 depends on PROC_FS 535 depends on PROC_FS
622 help 536 help
623 This enables the /proc/pid/seccomp_c 537 This enables the /proc/pid/seccomp_cache interface to monitor
624 seccomp cache data. The file format 538 seccomp cache data. The file format is subject to change. Reading
625 the file requires CAP_SYS_ADMIN. 539 the file requires CAP_SYS_ADMIN.
626 540
627 This option is for debugging only. E 541 This option is for debugging only. Enabling presents the risk that
628 an adversary may be able to infer th 542 an adversary may be able to infer the seccomp filter logic.
629 543
630 If unsure, say N. 544 If unsure, say N.
631 545
632 config HAVE_ARCH_STACKLEAK 546 config HAVE_ARCH_STACKLEAK
633 bool 547 bool
634 help 548 help
635 An architecture should select this i 549 An architecture should select this if it has the code which
636 fills the used part of the kernel st 550 fills the used part of the kernel stack with the STACKLEAK_POISON
637 value before returning from system c 551 value before returning from system calls.
638 552
639 config HAVE_STACKPROTECTOR 553 config HAVE_STACKPROTECTOR
640 bool 554 bool
641 help 555 help
642 An arch should select this symbol if 556 An arch should select this symbol if:
643 - it has implemented a stack canary 557 - it has implemented a stack canary (e.g. __stack_chk_guard)
644 558
645 config STACKPROTECTOR 559 config STACKPROTECTOR
646 bool "Stack Protector buffer overflow 560 bool "Stack Protector buffer overflow detection"
647 depends on HAVE_STACKPROTECTOR 561 depends on HAVE_STACKPROTECTOR
648 depends on $(cc-option,-fstack-protect 562 depends on $(cc-option,-fstack-protector)
649 default y 563 default y
650 help 564 help
651 This option turns on the "stack-prot 565 This option turns on the "stack-protector" GCC feature. This
652 feature puts, at the beginning of fu 566 feature puts, at the beginning of functions, a canary value on
653 the stack just before the return add 567 the stack just before the return address, and validates
654 the value just before actually retur 568 the value just before actually returning. Stack based buffer
655 overflows (that need to overwrite th 569 overflows (that need to overwrite this return address) now also
656 overwrite the canary, which gets det 570 overwrite the canary, which gets detected and the attack is then
657 neutralized via a kernel panic. 571 neutralized via a kernel panic.
658 572
659 Functions will have the stack-protec 573 Functions will have the stack-protector canary logic added if they
660 have an 8-byte or larger character a 574 have an 8-byte or larger character array on the stack.
661 575
662 This feature requires gcc version 4. 576 This feature requires gcc version 4.2 or above, or a distribution
663 gcc with the feature backported ("-f 577 gcc with the feature backported ("-fstack-protector").
664 578
665 On an x86 "defconfig" build, this fe 579 On an x86 "defconfig" build, this feature adds canary checks to
666 about 3% of all kernel functions, wh 580 about 3% of all kernel functions, which increases kernel code size
667 by about 0.3%. 581 by about 0.3%.
668 582
669 config STACKPROTECTOR_STRONG 583 config STACKPROTECTOR_STRONG
670 bool "Strong Stack Protector" 584 bool "Strong Stack Protector"
671 depends on STACKPROTECTOR 585 depends on STACKPROTECTOR
672 depends on $(cc-option,-fstack-protect 586 depends on $(cc-option,-fstack-protector-strong)
673 default y 587 default y
674 help 588 help
675 Functions will have the stack-protec 589 Functions will have the stack-protector canary logic added in any
676 of the following conditions: 590 of the following conditions:
677 591
678 - local variable's address used as p 592 - local variable's address used as part of the right hand side of an
679 assignment or function argument 593 assignment or function argument
680 - local variable is an array (or uni 594 - local variable is an array (or union containing an array),
681 regardless of array type or length 595 regardless of array type or length
682 - uses register local variables 596 - uses register local variables
683 597
684 This feature requires gcc version 4. 598 This feature requires gcc version 4.9 or above, or a distribution
685 gcc with the feature backported ("-f 599 gcc with the feature backported ("-fstack-protector-strong").
686 600
687 On an x86 "defconfig" build, this fe 601 On an x86 "defconfig" build, this feature adds canary checks to
688 about 20% of all kernel functions, w 602 about 20% of all kernel functions, which increases the kernel code
689 size by about 2%. 603 size by about 2%.
690 604
691 config ARCH_SUPPORTS_SHADOW_CALL_STACK 605 config ARCH_SUPPORTS_SHADOW_CALL_STACK
692 bool 606 bool
693 help 607 help
694 An architecture should select this i !! 608 An architecture should select this if it supports Clang's Shadow
695 Shadow Call Stack and implements run !! 609 Call Stack and implements runtime support for shadow stack
696 switching. 610 switching.
697 611
698 config SHADOW_CALL_STACK 612 config SHADOW_CALL_STACK
699 bool "Shadow Call Stack" !! 613 bool "Clang Shadow Call Stack"
700 depends on ARCH_SUPPORTS_SHADOW_CALL_S !! 614 depends on CC_IS_CLANG && ARCH_SUPPORTS_SHADOW_CALL_STACK
701 depends on DYNAMIC_FTRACE_WITH_ARGS || !! 615 depends on DYNAMIC_FTRACE_WITH_REGS || !FUNCTION_GRAPH_TRACER
702 depends on MMU 616 depends on MMU
703 help 617 help
704 This option enables the compiler's S !! 618 This option enables Clang's Shadow Call Stack, which uses a
705 uses a shadow stack to protect funct !! 619 shadow stack to protect function return addresses from being
706 being overwritten by an attacker. Mo !! 620 overwritten by an attacker. More information can be found in
707 in the compiler's documentation: !! 621 Clang's documentation:
708 622
709 - Clang: https://clang.llvm.org/docs !! 623 https://clang.llvm.org/docs/ShadowCallStack.html
710 - GCC: https://gcc.gnu.org/onlinedoc <<
711 624
712 Note that security guarantees in the 625 Note that security guarantees in the kernel differ from the
713 ones documented for user space. The 626 ones documented for user space. The kernel must store addresses
714 of shadow stacks in memory, which me 627 of shadow stacks in memory, which means an attacker capable of
715 reading and writing arbitrary memory 628 reading and writing arbitrary memory may be able to locate them
716 and hijack control flow by modifying 629 and hijack control flow by modifying the stacks.
717 630
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 631 config LTO
726 bool 632 bool
727 help 633 help
728 Selected if the kernel will be built 634 Selected if the kernel will be built using the compiler's LTO feature.
729 635
730 config LTO_CLANG 636 config LTO_CLANG
731 bool 637 bool
732 select LTO 638 select LTO
733 help 639 help
734 Selected if the kernel will be built 640 Selected if the kernel will be built using Clang's LTO feature.
735 641
736 config ARCH_SUPPORTS_LTO_CLANG 642 config ARCH_SUPPORTS_LTO_CLANG
737 bool 643 bool
738 help 644 help
739 An architecture should select this o 645 An architecture should select this option if it supports:
740 - compiling with Clang, 646 - compiling with Clang,
741 - compiling inline assembly with Cla 647 - compiling inline assembly with Clang's integrated assembler,
742 - and linking with LLD. 648 - and linking with LLD.
743 649
744 config ARCH_SUPPORTS_LTO_CLANG_THIN 650 config ARCH_SUPPORTS_LTO_CLANG_THIN
745 bool 651 bool
746 help 652 help
747 An architecture should select this o 653 An architecture should select this option if it can support Clang's
748 ThinLTO mode. 654 ThinLTO mode.
749 655
750 config HAS_LTO_CLANG 656 config HAS_LTO_CLANG
751 def_bool y 657 def_bool y
752 depends on CC_IS_CLANG && LD_IS_LLD && !! 658 # Clang >= 11: https://github.com/ClangBuiltLinux/linux/issues/510
>> 659 depends on CC_IS_CLANG && CLANG_VERSION >= 110000 && LD_IS_LLD && AS_IS_LLVM
753 depends on $(success,$(NM) --help | he 660 depends on $(success,$(NM) --help | head -n 1 | grep -qi llvm)
754 depends on $(success,$(AR) --help | he 661 depends on $(success,$(AR) --help | head -n 1 | grep -qi llvm)
755 depends on ARCH_SUPPORTS_LTO_CLANG 662 depends on ARCH_SUPPORTS_LTO_CLANG
756 depends on !FTRACE_MCOUNT_USE_RECORDMC 663 depends on !FTRACE_MCOUNT_USE_RECORDMCOUNT
757 # https://github.com/ClangBuiltLinux/l !! 664 depends on !KASAN || KASAN_HW_TAGS
758 depends on (!KASAN || KASAN_HW_TAGS || <<
759 depends on (!KCOV || CLANG_VERSION >= <<
760 depends on !GCOV_KERNEL 665 depends on !GCOV_KERNEL
761 help 666 help
762 The compiler and Kconfig options sup 667 The compiler and Kconfig options support building with Clang's
763 LTO. 668 LTO.
764 669
765 choice 670 choice
766 prompt "Link Time Optimization (LTO)" 671 prompt "Link Time Optimization (LTO)"
767 default LTO_NONE 672 default LTO_NONE
768 help 673 help
769 This option enables Link Time Optimi 674 This option enables Link Time Optimization (LTO), which allows the
770 compiler to optimize binaries global 675 compiler to optimize binaries globally.
771 676
772 If unsure, select LTO_NONE. Note tha 677 If unsure, select LTO_NONE. Note that LTO is very resource-intensive
773 so it's disabled by default. 678 so it's disabled by default.
774 679
775 config LTO_NONE 680 config LTO_NONE
776 bool "None" 681 bool "None"
777 help 682 help
778 Build the kernel normally, without L 683 Build the kernel normally, without Link Time Optimization (LTO).
779 684
780 config LTO_CLANG_FULL 685 config LTO_CLANG_FULL
781 bool "Clang Full LTO (EXPERIMENTAL)" 686 bool "Clang Full LTO (EXPERIMENTAL)"
782 depends on HAS_LTO_CLANG 687 depends on HAS_LTO_CLANG
783 depends on !COMPILE_TEST 688 depends on !COMPILE_TEST
784 select LTO_CLANG 689 select LTO_CLANG
785 help 690 help
786 This option enables Clang's full Lin !! 691 This option enables Clang's full Link Time Optimization (LTO), which
787 allows the compiler to optimize the !! 692 allows the compiler to optimize the kernel globally. If you enable
788 this option, the compiler generates !! 693 this option, the compiler generates LLVM bitcode instead of ELF
789 object files, and the actual compila !! 694 object files, and the actual compilation from bitcode happens at
790 the LTO link step, which may take se !! 695 the LTO link step, which may take several minutes depending on the
791 kernel configuration. More informati !! 696 kernel configuration. More information can be found from LLVM's
792 documentation: !! 697 documentation:
793 698
794 https://llvm.org/docs/LinkTimeOpti 699 https://llvm.org/docs/LinkTimeOptimization.html
795 700
796 During link time, this option can us 701 During link time, this option can use a large amount of RAM, and
797 may take much longer than the ThinLT 702 may take much longer than the ThinLTO option.
798 703
799 config LTO_CLANG_THIN 704 config LTO_CLANG_THIN
800 bool "Clang ThinLTO (EXPERIMENTAL)" 705 bool "Clang ThinLTO (EXPERIMENTAL)"
801 depends on HAS_LTO_CLANG && ARCH_SUPPO 706 depends on HAS_LTO_CLANG && ARCH_SUPPORTS_LTO_CLANG_THIN
802 select LTO_CLANG 707 select LTO_CLANG
803 help 708 help
804 This option enables Clang's ThinLTO, 709 This option enables Clang's ThinLTO, which allows for parallel
805 optimization and faster incremental 710 optimization and faster incremental compiles compared to the
806 CONFIG_LTO_CLANG_FULL option. More i 711 CONFIG_LTO_CLANG_FULL option. More information can be found
807 from Clang's documentation: 712 from Clang's documentation:
808 713
809 https://clang.llvm.org/docs/ThinLT 714 https://clang.llvm.org/docs/ThinLTO.html
810 715
811 If unsure, say Y. 716 If unsure, say Y.
812 endchoice 717 endchoice
813 718
814 config ARCH_SUPPORTS_CFI_CLANG 719 config ARCH_SUPPORTS_CFI_CLANG
815 bool 720 bool
816 help 721 help
817 An architecture should select this o 722 An architecture should select this option if it can support Clang's
818 Control-Flow Integrity (CFI) checkin 723 Control-Flow Integrity (CFI) checking.
819 724
820 config ARCH_USES_CFI_TRAPS <<
821 bool <<
822 <<
823 config CFI_CLANG 725 config CFI_CLANG
824 bool "Use Clang's Control Flow Integri 726 bool "Use Clang's Control Flow Integrity (CFI)"
825 depends on ARCH_SUPPORTS_CFI_CLANG !! 727 depends on LTO_CLANG && ARCH_SUPPORTS_CFI_CLANG
826 depends on $(cc-option,-fsanitize=kcfi !! 728 # Clang >= 12:
>> 729 # - https://bugs.llvm.org/show_bug.cgi?id=46258
>> 730 # - https://bugs.llvm.org/show_bug.cgi?id=47479
>> 731 depends on CLANG_VERSION >= 120000
>> 732 select KALLSYMS
827 help 733 help
828 This option enables Clang's forward- !! 734 This option enables Clang’s forward-edge Control Flow Integrity
829 (CFI) checking, where the compiler i 735 (CFI) checking, where the compiler injects a runtime check to each
830 indirect function call to ensure the 736 indirect function call to ensure the target is a valid function with
831 the correct static type. This restri 737 the correct static type. This restricts possible call targets and
832 makes it more difficult for an attac 738 makes it more difficult for an attacker to exploit bugs that allow
833 the modification of stored function 739 the modification of stored function pointers. More information can be
834 found from Clang's documentation: 740 found from Clang's documentation:
835 741
836 https://clang.llvm.org/docs/Contro 742 https://clang.llvm.org/docs/ControlFlowIntegrity.html
837 743
838 config CFI_ICALL_NORMALIZE_INTEGERS !! 744 config CFI_CLANG_SHADOW
839 bool "Normalize CFI tags for integers" !! 745 bool "Use CFI shadow to speed up cross-module checks"
840 depends on CFI_CLANG !! 746 default y
841 depends on HAVE_CFI_ICALL_NORMALIZE_IN !! 747 depends on CFI_CLANG && MODULES
842 help 748 help
843 This option normalizes the CFI tags !! 749 If you select this option, the kernel builds a fast look-up table of
844 integer types of the same size and s !! 750 CFI check functions in loaded modules to reduce performance overhead.
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 <<
853 751
854 config HAVE_CFI_ICALL_NORMALIZE_INTEGERS_CLANG !! 752 If unsure, say Y.
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 <<
867 753
868 config CFI_PERMISSIVE 754 config CFI_PERMISSIVE
869 bool "Use CFI in permissive mode" 755 bool "Use CFI in permissive mode"
870 depends on CFI_CLANG 756 depends on CFI_CLANG
871 help 757 help
872 When selected, Control Flow Integrit 758 When selected, Control Flow Integrity (CFI) violations result in a
873 warning instead of a kernel panic. T 759 warning instead of a kernel panic. This option should only be used
874 for finding indirect call type misma 760 for finding indirect call type mismatches during development.
875 761
876 If unsure, say N. 762 If unsure, say N.
877 763
878 config HAVE_ARCH_WITHIN_STACK_FRAMES 764 config HAVE_ARCH_WITHIN_STACK_FRAMES
879 bool 765 bool
880 help 766 help
881 An architecture should select this i 767 An architecture should select this if it can walk the kernel stack
882 frames to determine if an object is 768 frames to determine if an object is part of either the arguments
883 or local variables (i.e. that it exc 769 or local variables (i.e. that it excludes saved return addresses,
884 and similar) by implementing an inli 770 and similar) by implementing an inline arch_within_stack_frames(),
885 which is used by CONFIG_HARDENED_USE 771 which is used by CONFIG_HARDENED_USERCOPY.
886 772
887 config HAVE_CONTEXT_TRACKING_USER !! 773 config HAVE_CONTEXT_TRACKING
888 bool 774 bool
889 help 775 help
890 Provide kernel/user boundaries probe 776 Provide kernel/user boundaries probes necessary for subsystems
891 that need it, such as userspace RCU 777 that need it, such as userspace RCU extended quiescent state.
892 Syscalls need to be wrapped inside u 778 Syscalls need to be wrapped inside user_exit()-user_enter(), either
893 optimized behind static key or throu 779 optimized behind static key or through the slow path using TIF_NOHZ
894 flag. Exceptions handlers must be wr 780 flag. Exceptions handlers must be wrapped as well. Irqs are already
895 protected inside ct_irq_enter/ct_irq !! 781 protected inside rcu_irq_enter/rcu_irq_exit() but preemption or signal
896 handling on irq exit still need to b 782 handling on irq exit still need to be protected.
897 783
898 config HAVE_CONTEXT_TRACKING_USER_OFFSTACK !! 784 config HAVE_CONTEXT_TRACKING_OFFSTACK
899 bool 785 bool
900 help 786 help
901 Architecture neither relies on excep 787 Architecture neither relies on exception_enter()/exception_exit()
902 nor on schedule_user(). Also preempt 788 nor on schedule_user(). Also preempt_schedule_notrace() and
903 preempt_schedule_irq() can't be call 789 preempt_schedule_irq() can't be called in a preemptible section
904 while context tracking is CT_STATE_U !! 790 while context tracking is CONTEXT_USER. This feature reflects a sane
905 entry implementation where the follo 791 entry implementation where the following requirements are met on
906 critical entry code, ie: before user 792 critical entry code, ie: before user_exit() or after user_enter():
907 793
908 - Critical entry code isn't preempti 794 - Critical entry code isn't preemptible (or better yet:
909 not interruptible). 795 not interruptible).
910 - No use of RCU read side critical s !! 796 - No use of RCU read side critical sections, unless rcu_nmi_enter()
911 got called. 797 got called.
912 - No use of instrumentation, unless 798 - No use of instrumentation, unless instrumentation_begin() got
913 called. 799 called.
914 800
915 config HAVE_TIF_NOHZ 801 config HAVE_TIF_NOHZ
916 bool 802 bool
917 help 803 help
918 Arch relies on TIF_NOHZ and syscall 804 Arch relies on TIF_NOHZ and syscall slow path to implement context
919 tracking calls to user_enter()/user_ 805 tracking calls to user_enter()/user_exit().
920 806
921 config HAVE_VIRT_CPU_ACCOUNTING 807 config HAVE_VIRT_CPU_ACCOUNTING
922 bool 808 bool
923 809
924 config HAVE_VIRT_CPU_ACCOUNTING_IDLE 810 config HAVE_VIRT_CPU_ACCOUNTING_IDLE
925 bool 811 bool
926 help 812 help
927 Architecture has its own way to acco 813 Architecture has its own way to account idle CPU time and therefore
928 doesn't implement vtime_account_idle 814 doesn't implement vtime_account_idle().
929 815
930 config ARCH_HAS_SCALED_CPUTIME 816 config ARCH_HAS_SCALED_CPUTIME
931 bool 817 bool
932 818
933 config HAVE_VIRT_CPU_ACCOUNTING_GEN 819 config HAVE_VIRT_CPU_ACCOUNTING_GEN
934 bool 820 bool
935 default y if 64BIT 821 default y if 64BIT
936 help 822 help
937 With VIRT_CPU_ACCOUNTING_GEN, cputim 823 With VIRT_CPU_ACCOUNTING_GEN, cputime_t becomes 64-bit.
938 Before enabling this option, arch co 824 Before enabling this option, arch code must be audited
939 to ensure there are no races in conc 825 to ensure there are no races in concurrent read/write of
940 cputime_t. For example, reading/writ 826 cputime_t. For example, reading/writing 64-bit cputime_t on
941 some 32-bit arches may require multi 827 some 32-bit arches may require multiple accesses, so proper
942 locking is needed to protect against 828 locking is needed to protect against concurrent accesses.
943 829
944 config HAVE_IRQ_TIME_ACCOUNTING 830 config HAVE_IRQ_TIME_ACCOUNTING
945 bool 831 bool
946 help 832 help
947 Archs need to ensure they use a high 833 Archs need to ensure they use a high enough resolution clock to
948 support irq time accounting and then 834 support irq time accounting and then call enable_sched_clock_irqtime().
949 835
950 config HAVE_MOVE_PUD 836 config HAVE_MOVE_PUD
951 bool 837 bool
952 help 838 help
953 Architectures that select this are a 839 Architectures that select this are able to move page tables at the
954 PUD level. If there are only 3 page 840 PUD level. If there are only 3 page table levels, the move effectively
955 happens at the PGD level. 841 happens at the PGD level.
956 842
957 config HAVE_MOVE_PMD 843 config HAVE_MOVE_PMD
958 bool 844 bool
959 help 845 help
960 Archs that select this are able to m 846 Archs that select this are able to move page tables at the PMD level.
961 847
962 config HAVE_ARCH_TRANSPARENT_HUGEPAGE 848 config HAVE_ARCH_TRANSPARENT_HUGEPAGE
963 bool 849 bool
964 850
965 config HAVE_ARCH_TRANSPARENT_HUGEPAGE_PUD 851 config HAVE_ARCH_TRANSPARENT_HUGEPAGE_PUD
966 bool 852 bool
967 853
968 config HAVE_ARCH_HUGE_VMAP 854 config HAVE_ARCH_HUGE_VMAP
969 bool 855 bool
970 856
971 # 857 #
972 # Archs that select this would be capable of 858 # Archs that select this would be capable of PMD-sized vmaps (i.e.,
973 # arch_vmap_pmd_supported() returns true). Th !! 859 # arch_vmap_pmd_supported() returns true), and they must make no assumptions
974 # must be used to enable allocations to use h !! 860 # that vmalloc memory is mapped with PAGE_SIZE ptes. The VM_NO_HUGE_VMAP flag
>> 861 # can be used to prohibit arch-specific allocations from using hugepages to
>> 862 # help with this (e.g., modules may require it).
975 # 863 #
976 config HAVE_ARCH_HUGE_VMALLOC 864 config HAVE_ARCH_HUGE_VMALLOC
977 depends on HAVE_ARCH_HUGE_VMAP 865 depends on HAVE_ARCH_HUGE_VMAP
978 bool 866 bool
979 867
980 config ARCH_WANT_HUGE_PMD_SHARE 868 config ARCH_WANT_HUGE_PMD_SHARE
981 bool 869 bool
982 870
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 871 config HAVE_ARCH_SOFT_DIRTY
992 bool 872 bool
993 873
994 config HAVE_MOD_ARCH_SPECIFIC 874 config HAVE_MOD_ARCH_SPECIFIC
995 bool 875 bool
996 help 876 help
997 The arch uses struct mod_arch_specif 877 The arch uses struct mod_arch_specific to store data. Many arches
998 just need a simple module loader wit 878 just need a simple module loader without arch specific data - those
999 should not enable this. 879 should not enable this.
1000 880
1001 config MODULES_USE_ELF_RELA 881 config MODULES_USE_ELF_RELA
1002 bool 882 bool
1003 help 883 help
1004 Modules only use ELF RELA relocatio 884 Modules only use ELF RELA relocations. Modules with ELF REL
1005 relocations will give an error. 885 relocations will give an error.
1006 886
1007 config MODULES_USE_ELF_REL 887 config MODULES_USE_ELF_REL
1008 bool 888 bool
1009 help 889 help
1010 Modules only use ELF REL relocation 890 Modules only use ELF REL relocations. Modules with ELF RELA
1011 relocations will give an error. 891 relocations will give an error.
1012 892
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 893 config HAVE_IRQ_EXIT_ON_IRQ_STACK
1028 bool 894 bool
1029 help 895 help
1030 Architecture doesn't only execute t 896 Architecture doesn't only execute the irq handler on the irq stack
1031 but also irq_exit(). This way we ca 897 but also irq_exit(). This way we can process softirqs on this irq
1032 stack instead of switching to a new 898 stack instead of switching to a new one when we call __do_softirq()
1033 in the end of an hardirq. 899 in the end of an hardirq.
1034 This spares a stack switch and impr 900 This spares a stack switch and improves cache usage on softirq
1035 processing. 901 processing.
1036 902
1037 config HAVE_SOFTIRQ_ON_OWN_STACK 903 config HAVE_SOFTIRQ_ON_OWN_STACK
1038 bool 904 bool
1039 help 905 help
1040 Architecture provides a function to 906 Architecture provides a function to run __do_softirq() on a
1041 separate stack. 907 separate stack.
1042 908
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 909 config PGTABLE_LEVELS
1054 int 910 int
1055 default 2 911 default 2
1056 912
1057 config ARCH_HAS_ELF_RANDOMIZE 913 config ARCH_HAS_ELF_RANDOMIZE
1058 bool 914 bool
1059 help 915 help
1060 An architecture supports choosing r 916 An architecture supports choosing randomized locations for
1061 stack, mmap, brk, and ET_DYN. Defin 917 stack, mmap, brk, and ET_DYN. Defined functions:
1062 - arch_mmap_rnd() 918 - arch_mmap_rnd()
1063 - arch_randomize_brk() 919 - arch_randomize_brk()
1064 920
1065 config HAVE_ARCH_MMAP_RND_BITS 921 config HAVE_ARCH_MMAP_RND_BITS
1066 bool 922 bool
1067 help 923 help
1068 An arch should select this symbol i 924 An arch should select this symbol if it supports setting a variable
1069 number of bits for use in establish 925 number of bits for use in establishing the base address for mmap
1070 allocations, has MMU enabled and pr 926 allocations, has MMU enabled and provides values for both:
1071 - ARCH_MMAP_RND_BITS_MIN 927 - ARCH_MMAP_RND_BITS_MIN
1072 - ARCH_MMAP_RND_BITS_MAX 928 - ARCH_MMAP_RND_BITS_MAX
1073 929
1074 config HAVE_EXIT_THREAD 930 config HAVE_EXIT_THREAD
1075 bool 931 bool
1076 help 932 help
1077 An architecture implements exit_thr 933 An architecture implements exit_thread.
1078 934
1079 config ARCH_MMAP_RND_BITS_MIN 935 config ARCH_MMAP_RND_BITS_MIN
1080 int 936 int
1081 937
1082 config ARCH_MMAP_RND_BITS_MAX 938 config ARCH_MMAP_RND_BITS_MAX
1083 int 939 int
1084 940
1085 config ARCH_MMAP_RND_BITS_DEFAULT 941 config ARCH_MMAP_RND_BITS_DEFAULT
1086 int 942 int
1087 943
1088 config ARCH_MMAP_RND_BITS 944 config ARCH_MMAP_RND_BITS
1089 int "Number of bits to use for ASLR o 945 int "Number of bits to use for ASLR of mmap base address" if EXPERT
1090 range ARCH_MMAP_RND_BITS_MIN ARCH_MMA 946 range ARCH_MMAP_RND_BITS_MIN ARCH_MMAP_RND_BITS_MAX
1091 default ARCH_MMAP_RND_BITS_DEFAULT if 947 default ARCH_MMAP_RND_BITS_DEFAULT if ARCH_MMAP_RND_BITS_DEFAULT
1092 default ARCH_MMAP_RND_BITS_MIN 948 default ARCH_MMAP_RND_BITS_MIN
1093 depends on HAVE_ARCH_MMAP_RND_BITS 949 depends on HAVE_ARCH_MMAP_RND_BITS
1094 help 950 help
1095 This value can be used to select th 951 This value can be used to select the number of bits to use to
1096 determine the random offset to the 952 determine the random offset to the base address of vma regions
1097 resulting from mmap allocations. Th 953 resulting from mmap allocations. This value will be bounded
1098 by the architecture's minimum and m 954 by the architecture's minimum and maximum supported values.
1099 955
1100 This value can be changed after boo 956 This value can be changed after boot using the
1101 /proc/sys/vm/mmap_rnd_bits tunable 957 /proc/sys/vm/mmap_rnd_bits tunable
1102 958
1103 config HAVE_ARCH_MMAP_RND_COMPAT_BITS 959 config HAVE_ARCH_MMAP_RND_COMPAT_BITS
1104 bool 960 bool
1105 help 961 help
1106 An arch should select this symbol i 962 An arch should select this symbol if it supports running applications
1107 in compatibility mode, supports set 963 in compatibility mode, supports setting a variable number of bits for
1108 use in establishing the base addres 964 use in establishing the base address for mmap allocations, has MMU
1109 enabled and provides values for bot 965 enabled and provides values for both:
1110 - ARCH_MMAP_RND_COMPAT_BITS_MIN 966 - ARCH_MMAP_RND_COMPAT_BITS_MIN
1111 - ARCH_MMAP_RND_COMPAT_BITS_MAX 967 - ARCH_MMAP_RND_COMPAT_BITS_MAX
1112 968
1113 config ARCH_MMAP_RND_COMPAT_BITS_MIN 969 config ARCH_MMAP_RND_COMPAT_BITS_MIN
1114 int 970 int
1115 971
1116 config ARCH_MMAP_RND_COMPAT_BITS_MAX 972 config ARCH_MMAP_RND_COMPAT_BITS_MAX
1117 int 973 int
1118 974
1119 config ARCH_MMAP_RND_COMPAT_BITS_DEFAULT 975 config ARCH_MMAP_RND_COMPAT_BITS_DEFAULT
1120 int 976 int
1121 977
1122 config ARCH_MMAP_RND_COMPAT_BITS 978 config ARCH_MMAP_RND_COMPAT_BITS
1123 int "Number of bits to use for ASLR o 979 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 980 range ARCH_MMAP_RND_COMPAT_BITS_MIN ARCH_MMAP_RND_COMPAT_BITS_MAX
1125 default ARCH_MMAP_RND_COMPAT_BITS_DEF 981 default ARCH_MMAP_RND_COMPAT_BITS_DEFAULT if ARCH_MMAP_RND_COMPAT_BITS_DEFAULT
1126 default ARCH_MMAP_RND_COMPAT_BITS_MIN 982 default ARCH_MMAP_RND_COMPAT_BITS_MIN
1127 depends on HAVE_ARCH_MMAP_RND_COMPAT_ 983 depends on HAVE_ARCH_MMAP_RND_COMPAT_BITS
1128 help 984 help
1129 This value can be used to select th 985 This value can be used to select the number of bits to use to
1130 determine the random offset to the 986 determine the random offset to the base address of vma regions
1131 resulting from mmap allocations for 987 resulting from mmap allocations for compatible applications This
1132 value will be bounded by the archit 988 value will be bounded by the architecture's minimum and maximum
1133 supported values. 989 supported values.
1134 990
1135 This value can be changed after boo 991 This value can be changed after boot using the
1136 /proc/sys/vm/mmap_rnd_compat_bits t 992 /proc/sys/vm/mmap_rnd_compat_bits tunable
1137 993
1138 config HAVE_ARCH_COMPAT_MMAP_BASES 994 config HAVE_ARCH_COMPAT_MMAP_BASES
1139 bool 995 bool
1140 help 996 help
1141 This allows 64bit applications to i 997 This allows 64bit applications to invoke 32-bit mmap() syscall
1142 and vice-versa 32-bit applications 998 and vice-versa 32-bit applications to call 64-bit mmap().
1143 Required for applications doing dif 999 Required for applications doing different bitness syscalls.
1144 1000
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 1001 # This allows to use a set of generic functions to determine mmap base
1247 # address by giving priority to top-down sche 1002 # address by giving priority to top-down scheme only if the process
1248 # is not in legacy mode (compat task, unlimit 1003 # is not in legacy mode (compat task, unlimited stack size or
1249 # sysctl_legacy_va_layout). 1004 # sysctl_legacy_va_layout).
1250 # Architecture that selects this option can p 1005 # Architecture that selects this option can provide its own version of:
1251 # - STACK_RND_MASK 1006 # - STACK_RND_MASK
1252 config ARCH_WANT_DEFAULT_TOPDOWN_MMAP_LAYOUT 1007 config ARCH_WANT_DEFAULT_TOPDOWN_MMAP_LAYOUT
1253 bool 1008 bool
1254 depends on MMU 1009 depends on MMU
1255 select ARCH_HAS_ELF_RANDOMIZE 1010 select ARCH_HAS_ELF_RANDOMIZE
1256 1011
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 1012 config HAVE_STACK_VALIDATION
1274 bool 1013 bool
1275 help 1014 help
1276 Architecture supports objtool compi !! 1015 Architecture supports the 'objtool check' host tool command, which
1277 validation. !! 1016 performs compile-time stack metadata validation.
1278 1017
1279 config HAVE_RELIABLE_STACKTRACE 1018 config HAVE_RELIABLE_STACKTRACE
1280 bool 1019 bool
1281 help 1020 help
1282 Architecture has either save_stack_ 1021 Architecture has either save_stack_trace_tsk_reliable() or
1283 arch_stack_walk_reliable() function 1022 arch_stack_walk_reliable() function which only returns a stack trace
1284 if it can guarantee the trace is re 1023 if it can guarantee the trace is reliable.
1285 1024
1286 config HAVE_ARCH_HASH 1025 config HAVE_ARCH_HASH
1287 bool 1026 bool
1288 default n 1027 default n
1289 help 1028 help
1290 If this is set, the architecture pr 1029 If this is set, the architecture provides an <asm/hash.h>
1291 file which provides platform-specif 1030 file which provides platform-specific implementations of some
1292 functions in <linux/hash.h> or fs/n 1031 functions in <linux/hash.h> or fs/namei.c.
1293 1032
1294 config HAVE_ARCH_NVRAM_OPS 1033 config HAVE_ARCH_NVRAM_OPS
1295 bool 1034 bool
1296 1035
1297 config ISA_BUS_API 1036 config ISA_BUS_API
1298 def_bool ISA 1037 def_bool ISA
1299 1038
1300 # 1039 #
1301 # ABI hall of shame 1040 # ABI hall of shame
1302 # 1041 #
1303 config CLONE_BACKWARDS 1042 config CLONE_BACKWARDS
1304 bool 1043 bool
1305 help 1044 help
1306 Architecture has tls passed as the 1045 Architecture has tls passed as the 4th argument of clone(2),
1307 not the 5th one. 1046 not the 5th one.
1308 1047
1309 config CLONE_BACKWARDS2 1048 config CLONE_BACKWARDS2
1310 bool 1049 bool
1311 help 1050 help
1312 Architecture has the first two argu 1051 Architecture has the first two arguments of clone(2) swapped.
1313 1052
1314 config CLONE_BACKWARDS3 1053 config CLONE_BACKWARDS3
1315 bool 1054 bool
1316 help 1055 help
1317 Architecture has tls passed as the 1056 Architecture has tls passed as the 3rd argument of clone(2),
1318 not the 5th one. 1057 not the 5th one.
1319 1058
1320 config ODD_RT_SIGACTION 1059 config ODD_RT_SIGACTION
1321 bool 1060 bool
1322 help 1061 help
1323 Architecture has unusual rt_sigacti 1062 Architecture has unusual rt_sigaction(2) arguments
1324 1063
1325 config OLD_SIGSUSPEND 1064 config OLD_SIGSUSPEND
1326 bool 1065 bool
1327 help 1066 help
1328 Architecture has old sigsuspend(2) 1067 Architecture has old sigsuspend(2) syscall, of one-argument variety
1329 1068
1330 config OLD_SIGSUSPEND3 1069 config OLD_SIGSUSPEND3
1331 bool 1070 bool
1332 help 1071 help
1333 Even weirder antique ABI - three-ar 1072 Even weirder antique ABI - three-argument sigsuspend(2)
1334 1073
1335 config OLD_SIGACTION 1074 config OLD_SIGACTION
1336 bool 1075 bool
1337 help 1076 help
1338 Architecture has old sigaction(2) s 1077 Architecture has old sigaction(2) syscall. Nope, not the same
1339 as OLD_SIGSUSPEND | OLD_SIGSUSPEND3 1078 as OLD_SIGSUSPEND | OLD_SIGSUSPEND3 - alpha has sigsuspend(2),
1340 but fairly different variant of sig 1079 but fairly different variant of sigaction(2), thanks to OSF/1
1341 compatibility... 1080 compatibility...
1342 1081
1343 config COMPAT_OLD_SIGACTION 1082 config COMPAT_OLD_SIGACTION
1344 bool 1083 bool
1345 1084
1346 config COMPAT_32BIT_TIME 1085 config COMPAT_32BIT_TIME
1347 bool "Provide system calls for 32-bit 1086 bool "Provide system calls for 32-bit time_t"
1348 default !64BIT || COMPAT 1087 default !64BIT || COMPAT
1349 help 1088 help
1350 This enables 32 bit time_t support 1089 This enables 32 bit time_t support in addition to 64 bit time_t support.
1351 This is relevant on all 32-bit arch 1090 This is relevant on all 32-bit architectures, and 64-bit architectures
1352 as part of compat syscall handling. 1091 as part of compat syscall handling.
1353 1092
1354 config ARCH_NO_PREEMPT 1093 config ARCH_NO_PREEMPT
1355 bool 1094 bool
1356 1095
>> 1096 config ARCH_EPHEMERAL_INODES
>> 1097 def_bool n
>> 1098 help
>> 1099 An arch should select this symbol if it doesn't keep track of inode
>> 1100 instances on its own, but instead relies on something else (e.g. the
>> 1101 host kernel for an UML kernel).
>> 1102
1357 config ARCH_SUPPORTS_RT 1103 config ARCH_SUPPORTS_RT
1358 bool 1104 bool
1359 1105
1360 config CPU_NO_EFFICIENT_FFS 1106 config CPU_NO_EFFICIENT_FFS
1361 def_bool n 1107 def_bool n
1362 1108
1363 config HAVE_ARCH_VMAP_STACK 1109 config HAVE_ARCH_VMAP_STACK
1364 def_bool n 1110 def_bool n
1365 help 1111 help
1366 An arch should select this symbol i 1112 An arch should select this symbol if it can support kernel stacks
1367 in vmalloc space. This means: 1113 in vmalloc space. This means:
1368 1114
1369 - vmalloc space must be large enoug 1115 - vmalloc space must be large enough to hold many kernel stacks.
1370 This may rule out many 32-bit arc 1116 This may rule out many 32-bit architectures.
1371 1117
1372 - Stacks in vmalloc space need to w 1118 - Stacks in vmalloc space need to work reliably. For example, if
1373 vmap page tables are created on d 1119 vmap page tables are created on demand, either this mechanism
1374 needs to work while the stack poi 1120 needs to work while the stack points to a virtual address with
1375 unpopulated page tables or arch c 1121 unpopulated page tables or arch code (switch_to() and switch_mm(),
1376 most likely) needs to ensure that 1122 most likely) needs to ensure that the stack's page table entries
1377 are populated before running on a 1123 are populated before running on a possibly unpopulated stack.
1378 1124
1379 - If the stack overflows into a gua 1125 - If the stack overflows into a guard page, something reasonable
1380 should happen. The definition of 1126 should happen. The definition of "reasonable" is flexible, but
1381 instantly rebooting without loggi 1127 instantly rebooting without logging anything would be unfriendly.
1382 1128
1383 config VMAP_STACK 1129 config VMAP_STACK
1384 default y 1130 default y
1385 bool "Use a virtually-mapped stack" 1131 bool "Use a virtually-mapped stack"
1386 depends on HAVE_ARCH_VMAP_STACK 1132 depends on HAVE_ARCH_VMAP_STACK
1387 depends on !KASAN || KASAN_HW_TAGS || 1133 depends on !KASAN || KASAN_HW_TAGS || KASAN_VMALLOC
1388 help 1134 help
1389 Enable this if you want the use vir 1135 Enable this if you want the use virtually-mapped kernel stacks
1390 with guard pages. This causes kern 1136 with guard pages. This causes kernel stack overflows to be
1391 caught immediately rather than caus 1137 caught immediately rather than causing difficult-to-diagnose
1392 corruption. 1138 corruption.
1393 1139
1394 To use this with software KASAN mod 1140 To use this with software KASAN modes, the architecture must support
1395 backing virtual mappings with real 1141 backing virtual mappings with real shadow memory, and KASAN_VMALLOC
1396 must be enabled. 1142 must be enabled.
1397 1143
1398 config HAVE_ARCH_RANDOMIZE_KSTACK_OFFSET 1144 config HAVE_ARCH_RANDOMIZE_KSTACK_OFFSET
1399 def_bool n 1145 def_bool n
1400 help 1146 help
1401 An arch should select this symbol i 1147 An arch should select this symbol if it can support kernel stack
1402 offset randomization with calls to 1148 offset randomization with calls to add_random_kstack_offset()
1403 during syscall entry and choose_ran 1149 during syscall entry and choose_random_kstack_offset() during
1404 syscall exit. Careful removal of -f 1150 syscall exit. Careful removal of -fstack-protector-strong and
1405 -fstack-protector should also be ap 1151 -fstack-protector should also be applied to the entry code and
1406 closely examined, as the artificial 1152 closely examined, as the artificial stack bump looks like an array
1407 to the compiler, so it will attempt 1153 to the compiler, so it will attempt to add canary checks regardless
1408 of the static branch state. 1154 of the static branch state.
1409 1155
1410 config RANDOMIZE_KSTACK_OFFSET !! 1156 config RANDOMIZE_KSTACK_OFFSET_DEFAULT
1411 bool "Support for randomizing kernel !! 1157 bool "Randomize kernel stack offset on syscall entry"
1412 default y <<
1413 depends on HAVE_ARCH_RANDOMIZE_KSTACK 1158 depends on HAVE_ARCH_RANDOMIZE_KSTACK_OFFSET
1414 depends on INIT_STACK_NONE || !CC_IS_ 1159 depends on INIT_STACK_NONE || !CC_IS_CLANG || CLANG_VERSION >= 140000
1415 help 1160 help
1416 The kernel stack offset can be rand 1161 The kernel stack offset can be randomized (after pt_regs) by
1417 roughly 5 bits of entropy, frustrat 1162 roughly 5 bits of entropy, frustrating memory corruption
1418 attacks that depend on stack addres 1163 attacks that depend on stack address determinism or
1419 cross-syscall address exposures. !! 1164 cross-syscall address exposures. This feature is controlled
1420 !! 1165 by kernel boot param "randomize_kstack_offset=on/off", and this
1421 The feature is controlled via the " !! 1166 config chooses the default boot state.
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 1167
1435 config ARCH_OPTIONAL_KERNEL_RWX 1168 config ARCH_OPTIONAL_KERNEL_RWX
1436 def_bool n 1169 def_bool n
1437 1170
1438 config ARCH_OPTIONAL_KERNEL_RWX_DEFAULT 1171 config ARCH_OPTIONAL_KERNEL_RWX_DEFAULT
1439 def_bool n 1172 def_bool n
1440 1173
1441 config ARCH_HAS_STRICT_KERNEL_RWX 1174 config ARCH_HAS_STRICT_KERNEL_RWX
1442 def_bool n 1175 def_bool n
1443 1176
1444 config STRICT_KERNEL_RWX 1177 config STRICT_KERNEL_RWX
1445 bool "Make kernel text and rodata rea 1178 bool "Make kernel text and rodata read-only" if ARCH_OPTIONAL_KERNEL_RWX
1446 depends on ARCH_HAS_STRICT_KERNEL_RWX 1179 depends on ARCH_HAS_STRICT_KERNEL_RWX
1447 default !ARCH_OPTIONAL_KERNEL_RWX || 1180 default !ARCH_OPTIONAL_KERNEL_RWX || ARCH_OPTIONAL_KERNEL_RWX_DEFAULT
1448 help 1181 help
1449 If this is set, kernel text and rod 1182 If this is set, kernel text and rodata memory will be made read-only,
1450 and non-text memory will be made no 1183 and non-text memory will be made non-executable. This provides
1451 protection against certain security 1184 protection against certain security exploits (e.g. executing the heap
1452 or modifying text) 1185 or modifying text)
1453 1186
1454 These features are considered stand 1187 These features are considered standard security practice these days.
1455 You should say Y here in almost all 1188 You should say Y here in almost all cases.
1456 1189
1457 config ARCH_HAS_STRICT_MODULE_RWX 1190 config ARCH_HAS_STRICT_MODULE_RWX
1458 def_bool n 1191 def_bool n
1459 1192
1460 config STRICT_MODULE_RWX 1193 config STRICT_MODULE_RWX
1461 bool "Set loadable kernel module data 1194 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 1195 depends on ARCH_HAS_STRICT_MODULE_RWX && MODULES
1463 default !ARCH_OPTIONAL_KERNEL_RWX || 1196 default !ARCH_OPTIONAL_KERNEL_RWX || ARCH_OPTIONAL_KERNEL_RWX_DEFAULT
1464 help 1197 help
1465 If this is set, module text and rod 1198 If this is set, module text and rodata memory will be made read-only,
1466 and non-text memory will be made no 1199 and non-text memory will be made non-executable. This provides
1467 protection against certain security 1200 protection against certain security exploits (e.g. writing to text)
1468 1201
1469 # select if the architecture provides an asm/ 1202 # select if the architecture provides an asm/dma-direct.h header
1470 config ARCH_HAS_PHYS_TO_DMA 1203 config ARCH_HAS_PHYS_TO_DMA
1471 bool 1204 bool
1472 1205
1473 config HAVE_ARCH_COMPILER_H 1206 config HAVE_ARCH_COMPILER_H
1474 bool 1207 bool
1475 help 1208 help
1476 An architecture can select this if 1209 An architecture can select this if it provides an
1477 asm/compiler.h header that should b 1210 asm/compiler.h header that should be included after
1478 linux/compiler-*.h in order to over 1211 linux/compiler-*.h in order to override macro definitions that those
1479 headers generally provide. 1212 headers generally provide.
1480 1213
1481 config HAVE_ARCH_PREL32_RELOCATIONS 1214 config HAVE_ARCH_PREL32_RELOCATIONS
1482 bool 1215 bool
1483 help 1216 help
1484 May be selected by an architecture 1217 May be selected by an architecture if it supports place-relative
1485 32-bit relocations, both in the too 1218 32-bit relocations, both in the toolchain and in the module loader,
1486 in which case relative references c 1219 in which case relative references can be used in special sections
1487 for PCI fixup, initcalls etc which 1220 for PCI fixup, initcalls etc which are only half the size on 64 bit
1488 architectures, and don't require ru 1221 architectures, and don't require runtime relocation on relocatable
1489 kernels. 1222 kernels.
1490 1223
1491 config ARCH_USE_MEMREMAP_PROT 1224 config ARCH_USE_MEMREMAP_PROT
1492 bool 1225 bool
1493 1226
1494 config LOCK_EVENT_COUNTS 1227 config LOCK_EVENT_COUNTS
1495 bool "Locking event counts collection 1228 bool "Locking event counts collection"
1496 depends on DEBUG_FS 1229 depends on DEBUG_FS
1497 help 1230 help
1498 Enable light-weight counting of var 1231 Enable light-weight counting of various locking related events
1499 in the system with minimal performa 1232 in the system with minimal performance impact. This reduces
1500 the chance of application behavior 1233 the chance of application behavior change because of timing
1501 differences. The counts are reporte 1234 differences. The counts are reported via debugfs.
1502 1235
1503 # Select if the architecture has support for 1236 # Select if the architecture has support for applying RELR relocations.
1504 config ARCH_HAS_RELR 1237 config ARCH_HAS_RELR
1505 bool 1238 bool
1506 1239
1507 config RELR 1240 config RELR
1508 bool "Use RELR relocation packing" 1241 bool "Use RELR relocation packing"
1509 depends on ARCH_HAS_RELR && TOOLS_SUP 1242 depends on ARCH_HAS_RELR && TOOLS_SUPPORT_RELR
1510 default y 1243 default y
1511 help 1244 help
1512 Store the kernel's dynamic relocati 1245 Store the kernel's dynamic relocations in the RELR relocation packing
1513 format. Requires a compatible linke 1246 format. Requires a compatible linker (LLD supports this feature), as
1514 well as compatible NM and OBJCOPY u 1247 well as compatible NM and OBJCOPY utilities (llvm-nm and llvm-objcopy
1515 are compatible). 1248 are compatible).
1516 1249
1517 config ARCH_HAS_MEM_ENCRYPT 1250 config ARCH_HAS_MEM_ENCRYPT
1518 bool 1251 bool
1519 1252
1520 config ARCH_HAS_CC_PLATFORM 1253 config ARCH_HAS_CC_PLATFORM
1521 bool 1254 bool
1522 1255
1523 config HAVE_SPARSE_SYSCALL_NR 1256 config HAVE_SPARSE_SYSCALL_NR
1524 bool !! 1257 bool
1525 help !! 1258 help
1526 An architecture should select this !! 1259 An architecture should select this if its syscall numbering is sparse
1527 to save space. For example, MIPS ar 1260 to save space. For example, MIPS architecture has a syscall array with
1528 entries at 4000, 5000 and 6000 loca 1261 entries at 4000, 5000 and 6000 locations. This option turns on syscall
1529 related optimizations for a given a 1262 related optimizations for a given architecture.
1530 1263
1531 config ARCH_HAS_VDSO_DATA 1264 config ARCH_HAS_VDSO_DATA
1532 bool 1265 bool
1533 1266
1534 config HAVE_STATIC_CALL 1267 config HAVE_STATIC_CALL
1535 bool 1268 bool
1536 1269
1537 config HAVE_STATIC_CALL_INLINE 1270 config HAVE_STATIC_CALL_INLINE
1538 bool 1271 bool
1539 depends on HAVE_STATIC_CALL 1272 depends on HAVE_STATIC_CALL
1540 select OBJTOOL <<
1541 1273
1542 config HAVE_PREEMPT_DYNAMIC 1274 config HAVE_PREEMPT_DYNAMIC
1543 bool 1275 bool
1544 <<
1545 config HAVE_PREEMPT_DYNAMIC_CALL <<
1546 bool <<
1547 depends on HAVE_STATIC_CALL 1276 depends on HAVE_STATIC_CALL
1548 select HAVE_PREEMPT_DYNAMIC !! 1277 depends on GENERIC_ENTRY
1549 help 1278 help
1550 An architecture should select this !! 1279 Select this if the architecture support boot time preempt setting
1551 model being selected at boot time u !! 1280 on top of static calls. It is strongly advised to support inline
1552 !! 1281 static call to avoid any overhead.
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 1282
1580 config ARCH_WANT_LD_ORPHAN_WARN 1283 config ARCH_WANT_LD_ORPHAN_WARN
1581 bool 1284 bool
1582 help 1285 help
1583 An arch should select this symbol o 1286 An arch should select this symbol once all linker sections are explicitly
1584 included, size-asserted, or discard 1287 included, size-asserted, or discarded in the linker scripts. This is
1585 important because we never want exp 1288 important because we never want expected sections to be placed heuristically
1586 by the linker, since the locations 1289 by the linker, since the locations of such sections can change between linker
1587 versions. 1290 versions.
1588 1291
1589 config HAVE_ARCH_PFN_VALID 1292 config HAVE_ARCH_PFN_VALID
1590 bool 1293 bool
1591 1294
1592 config ARCH_SUPPORTS_DEBUG_PAGEALLOC 1295 config ARCH_SUPPORTS_DEBUG_PAGEALLOC
1593 bool 1296 bool
1594 1297
1595 config ARCH_SUPPORTS_PAGE_TABLE_CHECK <<
1596 bool <<
1597 <<
1598 config ARCH_SPLIT_ARG64 1298 config ARCH_SPLIT_ARG64
1599 bool 1299 bool
1600 help 1300 help
1601 If a 32-bit architecture requires 6 !! 1301 If a 32-bit architecture requires 64-bit arguments to be split into
1602 pairs of 32-bit arguments, select t !! 1302 pairs of 32-bit arguments, select this option.
1603 1303
1604 config ARCH_HAS_ELFCORE_COMPAT 1304 config ARCH_HAS_ELFCORE_COMPAT
1605 bool 1305 bool
1606 1306
1607 config ARCH_HAS_PARANOID_L1D_FLUSH 1307 config ARCH_HAS_PARANOID_L1D_FLUSH
1608 bool 1308 bool
1609 1309
1610 config ARCH_HAVE_TRACE_MMIO_ACCESS <<
1611 bool <<
1612 <<
1613 config DYNAMIC_SIGFRAME <<
1614 bool <<
1615 <<
1616 # Select, if arch has a named attribute group <<
1617 config HAVE_ARCH_NODE_DEV_GROUP <<
1618 bool <<
1619 <<
1620 config ARCH_HAS_HW_PTE_YOUNG <<
1621 bool <<
1622 help <<
1623 Architectures that select this opti <<
1624 accessed bit in PTE entries when us <<
1625 translations. Architectures that re <<
1626 this option and override arch_has_h <<
1627 <<
1628 config ARCH_HAS_NONLEAF_PMD_YOUNG <<
1629 bool <<
1630 help <<
1631 Architectures that select this opti <<
1632 accessed bit in non-leaf PMD entrie <<
1633 address translations. Page table wa <<
1634 may use this capability to reduce t <<
1635 <<
1636 config ARCH_HAS_KERNEL_FPU_SUPPORT <<
1637 bool <<
1638 help <<
1639 Architectures that select this opti <<
1640 the kernel, as described in Documen <<
1641 <<
1642 source "kernel/gcov/Kconfig" 1310 source "kernel/gcov/Kconfig"
1643 1311
1644 source "scripts/gcc-plugins/Kconfig" 1312 source "scripts/gcc-plugins/Kconfig"
1645 1313
1646 config FUNCTION_ALIGNMENT_4B 1314 config FUNCTION_ALIGNMENT_4B
1647 bool 1315 bool
1648 1316
1649 config FUNCTION_ALIGNMENT_8B 1317 config FUNCTION_ALIGNMENT_8B
1650 bool 1318 bool
1651 1319
1652 config FUNCTION_ALIGNMENT_16B 1320 config FUNCTION_ALIGNMENT_16B
1653 bool 1321 bool
1654 1322
1655 config FUNCTION_ALIGNMENT_32B 1323 config FUNCTION_ALIGNMENT_32B
1656 bool 1324 bool
1657 1325
1658 config FUNCTION_ALIGNMENT_64B 1326 config FUNCTION_ALIGNMENT_64B
1659 bool 1327 bool
1660 1328
1661 config FUNCTION_ALIGNMENT 1329 config FUNCTION_ALIGNMENT
1662 int 1330 int
1663 default 64 if FUNCTION_ALIGNMENT_64B 1331 default 64 if FUNCTION_ALIGNMENT_64B
1664 default 32 if FUNCTION_ALIGNMENT_32B 1332 default 32 if FUNCTION_ALIGNMENT_32B
1665 default 16 if FUNCTION_ALIGNMENT_16B 1333 default 16 if FUNCTION_ALIGNMENT_16B
1666 default 8 if FUNCTION_ALIGNMENT_8B 1334 default 8 if FUNCTION_ALIGNMENT_8B
1667 default 4 if FUNCTION_ALIGNMENT_4B 1335 default 4 if FUNCTION_ALIGNMENT_4B
1668 default 0 1336 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 1337
1685 endmenu 1338 endmenu
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