1 # SPDX-License-Identifier: GPL-2.0 1 # SPDX-License-Identifier: GPL-2.0
2 # 2 #
3 # General architecture dependent options 3 # General architecture dependent options
4 # 4 #
5 5
6 # 6 #
7 # Note: arch/$(SRCARCH)/Kconfig needs to be in 7 # Note: arch/$(SRCARCH)/Kconfig needs to be included first so that it can
8 # override the default values in this file. 8 # override the default values in this file.
9 # 9 #
10 source "arch/$(SRCARCH)/Kconfig" 10 source "arch/$(SRCARCH)/Kconfig"
11 11
12 config ARCH_CONFIGURES_CPU_MITIGATIONS <<
13 bool <<
14 <<
15 if !ARCH_CONFIGURES_CPU_MITIGATIONS <<
16 config CPU_MITIGATIONS <<
17 def_bool y <<
18 endif <<
19 <<
20 menu "General architecture-dependent options" 12 menu "General architecture-dependent options"
21 13
22 config ARCH_HAS_SUBPAGE_FAULTS !! 14 config CRASH_CORE
23 bool 15 bool
24 help <<
25 Select if the architecture can check <<
26 granularity (e.g. arm64 MTE). The pr <<
27 must be implemented. <<
28 16
29 config HOTPLUG_SMT !! 17 config KEXEC_CORE
>> 18 select CRASH_CORE
30 bool 19 bool
31 20
32 config SMT_NUM_THREADS_DYNAMIC !! 21 config KEXEC_ELF
33 bool 22 bool
34 23
35 # Selected by HOTPLUG_CORE_SYNC_DEAD or HOTPLU !! 24 config HAVE_IMA_KEXEC
36 config HOTPLUG_CORE_SYNC <<
37 bool 25 bool
38 26
39 # Basic CPU dead synchronization selected by a !! 27 config HOTPLUG_SMT
40 config HOTPLUG_CORE_SYNC_DEAD <<
41 bool 28 bool
42 select HOTPLUG_CORE_SYNC <<
43 29
44 # Full CPU synchronization with alive state se !! 30 config OPROFILE
45 config HOTPLUG_CORE_SYNC_FULL !! 31 tristate "OProfile system profiling"
46 bool !! 32 depends on PROFILING
47 select HOTPLUG_CORE_SYNC_DEAD if HOTPL !! 33 depends on HAVE_OPROFILE
48 select HOTPLUG_CORE_SYNC !! 34 select RING_BUFFER
>> 35 select RING_BUFFER_ALLOW_SWAP
>> 36 help
>> 37 OProfile is a profiling system capable of profiling the
>> 38 whole system, include the kernel, kernel modules, libraries,
>> 39 and applications.
49 40
50 config HOTPLUG_SPLIT_STARTUP !! 41 If unsure, say N.
51 bool <<
52 select HOTPLUG_CORE_SYNC_FULL <<
53 42
54 config HOTPLUG_PARALLEL !! 43 config OPROFILE_EVENT_MULTIPLEX
55 bool !! 44 bool "OProfile multiplexing support (EXPERIMENTAL)"
56 select HOTPLUG_SPLIT_STARTUP !! 45 default n
>> 46 depends on OPROFILE && X86
>> 47 help
>> 48 The number of hardware counters is limited. The multiplexing
>> 49 feature enables OProfile to gather more events than counters
>> 50 are provided by the hardware. This is realized by switching
>> 51 between events at a user specified time interval.
>> 52
>> 53 If unsure, say N.
57 54
58 config GENERIC_ENTRY !! 55 config HAVE_OPROFILE
59 bool 56 bool
60 57
>> 58 config OPROFILE_NMI_TIMER
>> 59 def_bool y
>> 60 depends on PERF_EVENTS && HAVE_PERF_EVENTS_NMI && !PPC64
>> 61
61 config KPROBES 62 config KPROBES
62 bool "Kprobes" 63 bool "Kprobes"
>> 64 depends on MODULES
63 depends on HAVE_KPROBES 65 depends on HAVE_KPROBES
64 select KALLSYMS 66 select KALLSYMS
65 select EXECMEM <<
66 select NEED_TASKS_RCU <<
67 help 67 help
68 Kprobes allows you to trap at almost 68 Kprobes allows you to trap at almost any kernel address and
69 execute a callback function. regist 69 execute a callback function. register_kprobe() establishes
70 a probepoint and specifies the callb 70 a probepoint and specifies the callback. Kprobes is useful
71 for kernel debugging, non-intrusive 71 for kernel debugging, non-intrusive instrumentation and testing.
72 If in doubt, say "N". 72 If in doubt, say "N".
73 73
74 config JUMP_LABEL 74 config JUMP_LABEL
75 bool "Optimize very unlikely/likely br !! 75 bool "Optimize very unlikely/likely branches"
76 depends on HAVE_ARCH_JUMP_LABEL !! 76 depends on HAVE_ARCH_JUMP_LABEL
77 select OBJTOOL if HAVE_JUMP_LABEL_HACK !! 77 depends on CC_HAS_ASM_GOTO
78 help !! 78 help
79 This option enables a transparent br !! 79 This option enables a transparent branch optimization that
80 makes certain almost-always-true or !! 80 makes certain almost-always-true or almost-always-false branch
81 conditions even cheaper to execute w !! 81 conditions even cheaper to execute within the kernel.
82 !! 82
83 Certain performance-sensitive kernel !! 83 Certain performance-sensitive kernel code, such as trace points,
84 scheduler functionality, networking !! 84 scheduler functionality, networking code and KVM have such
85 branches and include support for thi !! 85 branches and include support for this optimization technique.
86 !! 86
87 If it is detected that the compiler !! 87 If it is detected that the compiler has support for "asm goto",
88 the kernel will compile such branche !! 88 the kernel will compile such branches with just a nop
89 instruction. When the condition flag !! 89 instruction. When the condition flag is toggled to true, the
90 nop will be converted to a jump inst !! 90 nop will be converted to a jump instruction to execute the
91 conditional block of instructions. !! 91 conditional block of instructions.
92 !! 92
93 This technique lowers overhead and s !! 93 This technique lowers overhead and stress on the branch prediction
94 of the processor and generally makes !! 94 of the processor and generally makes the kernel faster. The update
95 of the condition is slower, but thos !! 95 of the condition is slower, but those are always very rare.
96 96
97 ( On 32-bit x86, the necessary optio !! 97 ( On 32-bit x86, the necessary options added to the compiler
98 flags may increase the size of the !! 98 flags may increase the size of the kernel slightly. )
99 99
100 config STATIC_KEYS_SELFTEST 100 config STATIC_KEYS_SELFTEST
101 bool "Static key selftest" 101 bool "Static key selftest"
102 depends on JUMP_LABEL 102 depends on JUMP_LABEL
103 help 103 help
104 Boot time self-test of the branch pa 104 Boot time self-test of the branch patching code.
105 105
106 config STATIC_CALL_SELFTEST <<
107 bool "Static call selftest" <<
108 depends on HAVE_STATIC_CALL <<
109 help <<
110 Boot time self-test of the call patc <<
111 <<
112 config OPTPROBES 106 config OPTPROBES
113 def_bool y 107 def_bool y
114 depends on KPROBES && HAVE_OPTPROBES 108 depends on KPROBES && HAVE_OPTPROBES
115 select NEED_TASKS_RCU !! 109 select TASKS_RCU if PREEMPTION
116 110
117 config KPROBES_ON_FTRACE 111 config KPROBES_ON_FTRACE
118 def_bool y 112 def_bool y
119 depends on KPROBES && HAVE_KPROBES_ON_ 113 depends on KPROBES && HAVE_KPROBES_ON_FTRACE
120 depends on DYNAMIC_FTRACE_WITH_REGS 114 depends on DYNAMIC_FTRACE_WITH_REGS
121 help 115 help
122 If function tracer is enabled and th !! 116 If function tracer is enabled and the arch supports full
123 passing of pt_regs to function traci !! 117 passing of pt_regs to function tracing, then kprobes can
124 optimize on top of function tracing. !! 118 optimize on top of function tracing.
125 119
126 config UPROBES 120 config UPROBES
127 def_bool n 121 def_bool n
128 depends on ARCH_SUPPORTS_UPROBES 122 depends on ARCH_SUPPORTS_UPROBES
129 help 123 help
130 Uprobes is the user-space counterpar 124 Uprobes is the user-space counterpart to kprobes: they
131 enable instrumentation applications 125 enable instrumentation applications (such as 'perf probe')
132 to establish unintrusive probes in u 126 to establish unintrusive probes in user-space binaries and
133 libraries, by executing handler func 127 libraries, by executing handler functions when the probes
134 are hit by user-space applications. 128 are hit by user-space applications.
135 129
136 ( These probes come in the form of s 130 ( These probes come in the form of single-byte breakpoints,
137 managed by the kernel and kept tra 131 managed by the kernel and kept transparent to the probed
138 application. ) 132 application. )
139 133
140 config HAVE_64BIT_ALIGNED_ACCESS 134 config HAVE_64BIT_ALIGNED_ACCESS
141 def_bool 64BIT && !HAVE_EFFICIENT_UNAL 135 def_bool 64BIT && !HAVE_EFFICIENT_UNALIGNED_ACCESS
142 help 136 help
143 Some architectures require 64 bit ac 137 Some architectures require 64 bit accesses to be 64 bit
144 aligned, which also requires structs 138 aligned, which also requires structs containing 64 bit values
145 to be 64 bit aligned too. This inclu 139 to be 64 bit aligned too. This includes some 32 bit
146 architectures which can do 64 bit ac 140 architectures which can do 64 bit accesses, as well as 64 bit
147 architectures without unaligned acce 141 architectures without unaligned access.
148 142
149 This symbol should be selected by an 143 This symbol should be selected by an architecture if 64 bit
150 accesses are required to be 64 bit a 144 accesses are required to be 64 bit aligned in this way even
151 though it is not a 64 bit architectu 145 though it is not a 64 bit architecture.
152 146
153 See Documentation/core-api/unaligned !! 147 See Documentation/unaligned-memory-access.txt for more
154 more information on the topic of una !! 148 information on the topic of unaligned memory accesses.
155 149
156 config HAVE_EFFICIENT_UNALIGNED_ACCESS 150 config HAVE_EFFICIENT_UNALIGNED_ACCESS
157 bool 151 bool
158 help 152 help
159 Some architectures are unable to per 153 Some architectures are unable to perform unaligned accesses
160 without the use of get_unaligned/put 154 without the use of get_unaligned/put_unaligned. Others are
161 unable to perform such accesses effi 155 unable to perform such accesses efficiently (e.g. trap on
162 unaligned access and require fixing 156 unaligned access and require fixing it up in the exception
163 handler.) 157 handler.)
164 158
165 This symbol should be selected by an 159 This symbol should be selected by an architecture if it can
166 perform unaligned accesses efficient 160 perform unaligned accesses efficiently to allow different
167 code paths to be selected for these 161 code paths to be selected for these cases. Some network
168 drivers, for example, could opt to n 162 drivers, for example, could opt to not fix up alignment
169 problems with received packets if do 163 problems with received packets if doing so would not help
170 much. 164 much.
171 165
172 See Documentation/core-api/unaligned !! 166 See Documentation/unaligned-memory-access.txt for more
173 information on the topic of unaligne 167 information on the topic of unaligned memory accesses.
174 168
175 config ARCH_USE_BUILTIN_BSWAP 169 config ARCH_USE_BUILTIN_BSWAP
176 bool !! 170 bool
177 help !! 171 help
178 Modern versions of GCC (since 4.4) h !! 172 Modern versions of GCC (since 4.4) have builtin functions
179 for handling byte-swapping. Using th !! 173 for handling byte-swapping. Using these, instead of the old
180 inline assembler that the architectu !! 174 inline assembler that the architecture code provides in the
181 __arch_bswapXX() macros, allows the !! 175 __arch_bswapXX() macros, allows the compiler to see what's
182 happening and offers more opportunit !! 176 happening and offers more opportunity for optimisation. In
183 particular, the compiler will be abl !! 177 particular, the compiler will be able to combine the byteswap
184 with a nearby load or store and use !! 178 with a nearby load or store and use load-and-swap or
185 store-and-swap instructions if the a !! 179 store-and-swap instructions if the architecture has them. It
186 should almost *never* result in code !! 180 should almost *never* result in code which is worse than the
187 hand-coded assembler in <asm/swab.h> !! 181 hand-coded assembler in <asm/swab.h>. But just in case it
188 does, the use of the builtins is opt !! 182 does, the use of the builtins is optional.
189 !! 183
190 Any architecture with load-and-swap !! 184 Any architecture with load-and-swap or store-and-swap
191 instructions should set this. And it !! 185 instructions should set this. And it shouldn't hurt to set it
192 on architectures that don't have suc !! 186 on architectures that don't have such instructions.
193 187
194 config KRETPROBES 188 config KRETPROBES
195 def_bool y 189 def_bool y
196 depends on KPROBES && (HAVE_KRETPROBES !! 190 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 <<
203 191
204 config USER_RETURN_NOTIFIER 192 config USER_RETURN_NOTIFIER
205 bool 193 bool
206 depends on HAVE_USER_RETURN_NOTIFIER 194 depends on HAVE_USER_RETURN_NOTIFIER
207 help 195 help
208 Provide a kernel-internal notificati 196 Provide a kernel-internal notification when a cpu is about to
209 switch to user mode. 197 switch to user mode.
210 198
211 config HAVE_IOREMAP_PROT 199 config HAVE_IOREMAP_PROT
212 bool 200 bool
213 201
214 config HAVE_KPROBES 202 config HAVE_KPROBES
215 bool 203 bool
216 204
217 config HAVE_KRETPROBES 205 config HAVE_KRETPROBES
218 bool 206 bool
219 207
220 config HAVE_OPTPROBES 208 config HAVE_OPTPROBES
221 bool 209 bool
222 210
223 config HAVE_KPROBES_ON_FTRACE 211 config HAVE_KPROBES_ON_FTRACE
224 bool 212 bool
225 213
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 214 config HAVE_FUNCTION_ERROR_INJECTION
235 bool 215 bool
236 216
237 config HAVE_NMI 217 config HAVE_NMI
238 bool 218 bool
239 219
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 # 220 #
250 # An arch should select this if it provides al 221 # An arch should select this if it provides all these things:
251 # 222 #
252 # task_pt_regs() in asm/process 223 # task_pt_regs() in asm/processor.h or asm/ptrace.h
253 # arch_has_single_step() if there is ha 224 # arch_has_single_step() if there is hardware single-step support
254 # arch_has_block_step() if there is ha 225 # arch_has_block_step() if there is hardware block-step support
255 # asm/syscall.h supplying asm- 226 # asm/syscall.h supplying asm-generic/syscall.h interface
256 # linux/regset.h user_regset in 227 # linux/regset.h user_regset interfaces
257 # CORE_DUMP_USE_REGSET #define'd in l 228 # CORE_DUMP_USE_REGSET #define'd in linux/elf.h
258 # TIF_SYSCALL_TRACE calls ptrace_r !! 229 # TIF_SYSCALL_TRACE calls tracehook_report_syscall_{entry,exit}
259 # TIF_NOTIFY_RESUME calls resume_u !! 230 # TIF_NOTIFY_RESUME calls tracehook_notify_resume()
>> 231 # signal delivery calls tracehook_signal_handler()
260 # 232 #
261 config HAVE_ARCH_TRACEHOOK 233 config HAVE_ARCH_TRACEHOOK
262 bool 234 bool
263 235
264 config HAVE_DMA_CONTIGUOUS 236 config HAVE_DMA_CONTIGUOUS
265 bool 237 bool
266 238
267 config GENERIC_SMP_IDLE_THREAD 239 config GENERIC_SMP_IDLE_THREAD
268 bool !! 240 bool
269 241
270 config GENERIC_IDLE_POLL_SETUP 242 config GENERIC_IDLE_POLL_SETUP
271 bool !! 243 bool
272 244
273 config ARCH_HAS_FORTIFY_SOURCE 245 config ARCH_HAS_FORTIFY_SOURCE
274 bool 246 bool
275 help 247 help
276 An architecture should select this w 248 An architecture should select this when it can successfully
277 build and run with CONFIG_FORTIFY_SO 249 build and run with CONFIG_FORTIFY_SOURCE.
278 250
279 # 251 #
280 # Select if the arch provides a historic keepi 252 # Select if the arch provides a historic keepinit alias for the retain_initrd
281 # command line option 253 # command line option
282 # 254 #
283 config ARCH_HAS_KEEPINITRD 255 config ARCH_HAS_KEEPINITRD
284 bool 256 bool
285 257
286 # Select if arch has all set_memory_ro/rw/x/nx 258 # Select if arch has all set_memory_ro/rw/x/nx() functions in asm/cacheflush.h
287 config ARCH_HAS_SET_MEMORY 259 config ARCH_HAS_SET_MEMORY
288 bool 260 bool
289 261
290 # Select if arch has all set_direct_map_invali 262 # Select if arch has all set_direct_map_invalid/default() functions
291 config ARCH_HAS_SET_DIRECT_MAP 263 config ARCH_HAS_SET_DIRECT_MAP
292 bool 264 bool
293 265
294 # 266 #
295 # Select if the architecture provides the arch !! 267 # Select if arch has an uncached kernel segment and provides the
296 # either provide an uncached segment alias for !! 268 # uncached_kernel_address / cached_kernel_address symbols to use it
297 # to remap the page tables in place. <<
298 # 269 #
299 config ARCH_HAS_DMA_SET_UNCACHED !! 270 config ARCH_HAS_UNCACHED_SEGMENT
300 bool !! 271 select ARCH_HAS_DMA_PREP_COHERENT
301 <<
302 # <<
303 # Select if the architectures provides the arc <<
304 # to undo an in-place page table remap for unc <<
305 # <<
306 config ARCH_HAS_DMA_CLEAR_UNCACHED <<
307 bool 272 bool
308 273
309 config ARCH_HAS_CPU_FINALIZE_INIT 274 config ARCH_HAS_CPU_FINALIZE_INIT
310 bool 275 bool
311 276
312 # The architecture has a per-task state that i !! 277 # Select if arch init_task must go in the __init_task_data section
313 config ARCH_HAS_CPU_PASID !! 278 config ARCH_TASK_STRUCT_ON_STACK
>> 279 bool
>> 280
>> 281 # Select if arch has its private alloc_task_struct() function
>> 282 config ARCH_TASK_STRUCT_ALLOCATOR
314 bool 283 bool
315 select IOMMU_MM_DATA <<
316 284
317 config HAVE_ARCH_THREAD_STRUCT_WHITELIST 285 config HAVE_ARCH_THREAD_STRUCT_WHITELIST
318 bool 286 bool
>> 287 depends on !ARCH_TASK_STRUCT_ALLOCATOR
319 help 288 help
320 An architecture should select this t 289 An architecture should select this to provide hardened usercopy
321 knowledge about what region of the t 290 knowledge about what region of the thread_struct should be
322 whitelisted for copying to userspace 291 whitelisted for copying to userspace. Normally this is only the
323 FPU registers. Specifically, arch_th 292 FPU registers. Specifically, arch_thread_struct_whitelist()
324 should be implemented. Without this, 293 should be implemented. Without this, the entire thread_struct
325 field in task_struct will be left wh 294 field in task_struct will be left whitelisted.
326 295
327 # Select if arch wants to size task_struct dyn !! 296 # Select if arch has its private alloc_thread_stack() function
328 config ARCH_WANTS_DYNAMIC_TASK_STRUCT !! 297 config ARCH_THREAD_STACK_ALLOCATOR
329 bool 298 bool
330 299
331 config ARCH_WANTS_NO_INSTR !! 300 # Select if arch wants to size task_struct dynamically via arch_task_struct_size:
>> 301 config ARCH_WANTS_DYNAMIC_TASK_STRUCT
332 bool 302 bool
333 help <<
334 An architecture should select this i <<
335 functions to denote that the toolcha <<
336 functions and is required for correc <<
337 303
338 config ARCH_32BIT_OFF_T 304 config ARCH_32BIT_OFF_T
339 bool 305 bool
340 depends on !64BIT 306 depends on !64BIT
341 help 307 help
342 All new 32-bit architectures should 308 All new 32-bit architectures should have 64-bit off_t type on
343 userspace side which corresponds to 309 userspace side which corresponds to the loff_t kernel type. This
344 is the requirement for modern ABIs. 310 is the requirement for modern ABIs. Some existing architectures
345 still support 32-bit off_t. This opt 311 still support 32-bit off_t. This option is enabled for all such
346 architectures explicitly. 312 architectures explicitly.
347 313
348 # Selected by 64 bit architectures which have <<
349 config ARCH_32BIT_USTAT_F_TINODE <<
350 bool <<
351 <<
352 config HAVE_ASM_MODVERSIONS 314 config HAVE_ASM_MODVERSIONS
353 bool 315 bool
354 help 316 help
355 This symbol should be selected by an !! 317 This symbol should be selected by an architecure if it provides
356 <asm/asm-prototypes.h> to support th 318 <asm/asm-prototypes.h> to support the module versioning for symbols
357 exported from assembly code. 319 exported from assembly code.
358 320
359 config HAVE_REGS_AND_STACK_ACCESS_API 321 config HAVE_REGS_AND_STACK_ACCESS_API
360 bool 322 bool
361 help 323 help
362 This symbol should be selected by an !! 324 This symbol should be selected by an architecure if it supports
363 the API needed to access registers a 325 the API needed to access registers and stack entries from pt_regs,
364 declared in asm/ptrace.h 326 declared in asm/ptrace.h
365 For example the kprobes-based event 327 For example the kprobes-based event tracer needs this API.
366 328
367 config HAVE_RSEQ 329 config HAVE_RSEQ
368 bool 330 bool
369 depends on HAVE_REGS_AND_STACK_ACCESS_ 331 depends on HAVE_REGS_AND_STACK_ACCESS_API
370 help 332 help
371 This symbol should be selected by an 333 This symbol should be selected by an architecture if it
372 supports an implementation of restar 334 supports an implementation of restartable sequences.
373 335
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 336 config HAVE_FUNCTION_ARG_ACCESS_API
381 bool 337 bool
382 help 338 help
383 This symbol should be selected by an !! 339 This symbol should be selected by an architecure if it supports
384 the API needed to access function ar 340 the API needed to access function arguments from pt_regs,
385 declared in asm/ptrace.h 341 declared in asm/ptrace.h
386 342
>> 343 config HAVE_CLK
>> 344 bool
>> 345 help
>> 346 The <linux/clk.h> calls support software clock gating and
>> 347 thus are a key power management tool on many systems.
>> 348
387 config HAVE_HW_BREAKPOINT 349 config HAVE_HW_BREAKPOINT
388 bool 350 bool
389 depends on PERF_EVENTS 351 depends on PERF_EVENTS
390 352
391 config HAVE_MIXED_BREAKPOINTS_REGS 353 config HAVE_MIXED_BREAKPOINTS_REGS
392 bool 354 bool
393 depends on HAVE_HW_BREAKPOINT 355 depends on HAVE_HW_BREAKPOINT
394 help 356 help
395 Depending on the arch implementation 357 Depending on the arch implementation of hardware breakpoints,
396 some of them have separate registers 358 some of them have separate registers for data and instruction
397 breakpoints addresses, others have m 359 breakpoints addresses, others have mixed registers to store
398 them but define the access type in a 360 them but define the access type in a control register.
399 Select this option if your arch impl 361 Select this option if your arch implements breakpoints under the
400 latter fashion. 362 latter fashion.
401 363
402 config HAVE_USER_RETURN_NOTIFIER 364 config HAVE_USER_RETURN_NOTIFIER
403 bool 365 bool
404 366
405 config HAVE_PERF_EVENTS_NMI 367 config HAVE_PERF_EVENTS_NMI
406 bool 368 bool
407 help 369 help
408 System hardware can generate an NMI 370 System hardware can generate an NMI using the perf event
409 subsystem. Also has support for cal 371 subsystem. Also has support for calculating CPU cycle events
410 to determine how many clock cycles i 372 to determine how many clock cycles in a given period.
411 373
412 config HAVE_HARDLOCKUP_DETECTOR_PERF 374 config HAVE_HARDLOCKUP_DETECTOR_PERF
413 bool 375 bool
414 depends on HAVE_PERF_EVENTS_NMI 376 depends on HAVE_PERF_EVENTS_NMI
415 help 377 help
416 The arch chooses to use the generic 378 The arch chooses to use the generic perf-NMI-based hardlockup
417 detector. Must define HAVE_PERF_EVEN 379 detector. Must define HAVE_PERF_EVENTS_NMI.
418 380
419 config HAVE_HARDLOCKUP_DETECTOR_ARCH !! 381 config HAVE_NMI_WATCHDOG
>> 382 depends on HAVE_NMI
420 bool 383 bool
421 help 384 help
422 The arch provides its own hardlockup !! 385 The arch provides a low level NMI watchdog. It provides
423 of the generic ones. !! 386 asm/nmi.h, and defines its own arch_touch_nmi_watchdog().
424 387
425 It uses the same command line parame !! 388 config HAVE_HARDLOCKUP_DETECTOR_ARCH
426 as the generic hardlockup detectors. !! 389 bool
>> 390 select HAVE_NMI_WATCHDOG
>> 391 help
>> 392 The arch chooses to provide its own hardlockup detector, which is
>> 393 a superset of the HAVE_NMI_WATCHDOG. It also conforms to config
>> 394 interfaces and parameters provided by hardlockup detector subsystem.
427 395
428 config HAVE_PERF_REGS 396 config HAVE_PERF_REGS
429 bool 397 bool
430 help 398 help
431 Support selective register dumps for 399 Support selective register dumps for perf events. This includes
432 bit-mapping of each registers and a 400 bit-mapping of each registers and a unique architecture id.
433 401
434 config HAVE_PERF_USER_STACK_DUMP 402 config HAVE_PERF_USER_STACK_DUMP
435 bool 403 bool
436 help 404 help
437 Support user stack dumps for perf ev 405 Support user stack dumps for perf event samples. This needs
438 access to the user stack pointer whi 406 access to the user stack pointer which is not unified across
439 architectures. 407 architectures.
440 408
441 config HAVE_ARCH_JUMP_LABEL 409 config HAVE_ARCH_JUMP_LABEL
442 bool 410 bool
443 411
444 config HAVE_ARCH_JUMP_LABEL_RELATIVE 412 config HAVE_ARCH_JUMP_LABEL_RELATIVE
445 bool 413 bool
446 414
447 config MMU_GATHER_TABLE_FREE !! 415 config HAVE_RCU_TABLE_FREE
448 bool <<
449 <<
450 config MMU_GATHER_RCU_TABLE_FREE <<
451 bool 416 bool
452 select MMU_GATHER_TABLE_FREE <<
453 417
454 config MMU_GATHER_PAGE_SIZE !! 418 config HAVE_MMU_GATHER_PAGE_SIZE
455 bool 419 bool
456 420
457 config MMU_GATHER_NO_RANGE 421 config MMU_GATHER_NO_RANGE
458 bool 422 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 <<
466 423
467 config MMU_GATHER_NO_GATHER !! 424 config HAVE_MMU_GATHER_NO_GATHER
468 bool 425 bool
469 depends on MMU_GATHER_TABLE_FREE <<
470 426
471 config ARCH_WANT_IRQS_OFF_ACTIVATE_MM 427 config ARCH_WANT_IRQS_OFF_ACTIVATE_MM
472 bool 428 bool
473 help 429 help
474 Temporary select until all architect 430 Temporary select until all architectures can be converted to have
475 irqs disabled over activate_mm. Arch 431 irqs disabled over activate_mm. Architectures that do IPI based TLB
476 shootdowns should enable this. 432 shootdowns should enable this.
477 433
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 434 config ARCH_HAVE_NMI_SAFE_CMPXCHG
511 bool 435 bool
512 436
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 437 config HAVE_ALIGNED_STRUCT_PAGE
526 bool 438 bool
527 help 439 help
528 This makes sure that struct pages ar 440 This makes sure that struct pages are double word aligned and that
529 e.g. the SLUB allocator can perform 441 e.g. the SLUB allocator can perform double word atomic operations
530 on a struct page for better performa 442 on a struct page for better performance. However selecting this
531 might increase the size of a struct 443 might increase the size of a struct page by a word.
532 444
533 config HAVE_CMPXCHG_LOCAL 445 config HAVE_CMPXCHG_LOCAL
534 bool 446 bool
535 447
536 config HAVE_CMPXCHG_DOUBLE 448 config HAVE_CMPXCHG_DOUBLE
537 bool 449 bool
538 450
539 config ARCH_WEAK_RELEASE_ACQUIRE 451 config ARCH_WEAK_RELEASE_ACQUIRE
540 bool 452 bool
541 453
542 config ARCH_WANT_IPC_PARSE_VERSION 454 config ARCH_WANT_IPC_PARSE_VERSION
543 bool 455 bool
544 456
545 config ARCH_WANT_COMPAT_IPC_PARSE_VERSION 457 config ARCH_WANT_COMPAT_IPC_PARSE_VERSION
546 bool 458 bool
547 459
548 config ARCH_WANT_OLD_COMPAT_IPC 460 config ARCH_WANT_OLD_COMPAT_IPC
549 select ARCH_WANT_COMPAT_IPC_PARSE_VERS 461 select ARCH_WANT_COMPAT_IPC_PARSE_VERSION
550 bool 462 bool
551 463
552 config HAVE_ARCH_SECCOMP <<
553 bool <<
554 help <<
555 An arch should select this symbol to <<
556 syscall policy), and must provide an <<
557 and compat syscalls if the asm-gener <<
558 - __NR_seccomp_read_32 <<
559 - __NR_seccomp_write_32 <<
560 - __NR_seccomp_exit_32 <<
561 - __NR_seccomp_sigreturn_32 <<
562 <<
563 config HAVE_ARCH_SECCOMP_FILTER 464 config HAVE_ARCH_SECCOMP_FILTER
564 bool 465 bool
565 select HAVE_ARCH_SECCOMP <<
566 help 466 help
567 An arch should select this symbol if 467 An arch should select this symbol if it provides all of these things:
568 - all the requirements for HAVE_ARCH <<
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 <<
579 SECCOMP_ARCH_NATIVE_NR, SECCOMP_AR <<
580 COMPAT is supported, have the SECC <<
581 <<
582 config SECCOMP <<
583 prompt "Enable seccomp to safely execu <<
584 def_bool y <<
585 depends on HAVE_ARCH_SECCOMP <<
586 help <<
587 This kernel feature is useful for nu <<
588 that may need to handle untrusted by <<
589 execution. By using pipes or other t <<
590 to the process as file descriptors s <<
591 syscalls, it's possible to isolate t <<
592 own address space using seccomp. Onc <<
593 prctl(PR_SET_SECCOMP) or the seccomp <<
594 disabled and the task is only allowe <<
595 syscalls defined by each seccomp mod <<
596 <<
597 If unsure, say Y. <<
598 477
599 config SECCOMP_FILTER 478 config SECCOMP_FILTER
600 def_bool y 479 def_bool y
601 depends on HAVE_ARCH_SECCOMP_FILTER && 480 depends on HAVE_ARCH_SECCOMP_FILTER && SECCOMP && NET
602 help 481 help
603 Enable tasks to build secure computi 482 Enable tasks to build secure computing environments defined
604 in terms of Berkeley Packet Filter p 483 in terms of Berkeley Packet Filter programs which implement
605 task-defined system call filtering p 484 task-defined system call filtering polices.
606 485
607 See Documentation/userspace-api/secc 486 See Documentation/userspace-api/seccomp_filter.rst for details.
608 487
609 config SECCOMP_CACHE_DEBUG <<
610 bool "Show seccomp filter cache status <<
611 depends on SECCOMP_FILTER && !HAVE_SPA <<
612 depends on PROC_FS <<
613 help <<
614 This enables the /proc/pid/seccomp_c <<
615 seccomp cache data. The file format <<
616 the file requires CAP_SYS_ADMIN. <<
617 <<
618 This option is for debugging only. E <<
619 an adversary may be able to infer th <<
620 <<
621 If unsure, say N. <<
622 <<
623 config HAVE_ARCH_STACKLEAK 488 config HAVE_ARCH_STACKLEAK
624 bool 489 bool
625 help 490 help
626 An architecture should select this i 491 An architecture should select this if it has the code which
627 fills the used part of the kernel st 492 fills the used part of the kernel stack with the STACKLEAK_POISON
628 value before returning from system c 493 value before returning from system calls.
629 494
630 config HAVE_STACKPROTECTOR 495 config HAVE_STACKPROTECTOR
631 bool 496 bool
632 help 497 help
633 An arch should select this symbol if 498 An arch should select this symbol if:
634 - it has implemented a stack canary 499 - it has implemented a stack canary (e.g. __stack_chk_guard)
635 500
>> 501 config CC_HAS_STACKPROTECTOR_NONE
>> 502 def_bool $(cc-option,-fno-stack-protector)
>> 503
636 config STACKPROTECTOR 504 config STACKPROTECTOR
637 bool "Stack Protector buffer overflow 505 bool "Stack Protector buffer overflow detection"
638 depends on HAVE_STACKPROTECTOR 506 depends on HAVE_STACKPROTECTOR
639 depends on $(cc-option,-fstack-protect 507 depends on $(cc-option,-fstack-protector)
640 default y 508 default y
641 help 509 help
642 This option turns on the "stack-prot 510 This option turns on the "stack-protector" GCC feature. This
643 feature puts, at the beginning of fu 511 feature puts, at the beginning of functions, a canary value on
644 the stack just before the return add 512 the stack just before the return address, and validates
645 the value just before actually retur 513 the value just before actually returning. Stack based buffer
646 overflows (that need to overwrite th 514 overflows (that need to overwrite this return address) now also
647 overwrite the canary, which gets det 515 overwrite the canary, which gets detected and the attack is then
648 neutralized via a kernel panic. 516 neutralized via a kernel panic.
649 517
650 Functions will have the stack-protec 518 Functions will have the stack-protector canary logic added if they
651 have an 8-byte or larger character a 519 have an 8-byte or larger character array on the stack.
652 520
653 This feature requires gcc version 4. 521 This feature requires gcc version 4.2 or above, or a distribution
654 gcc with the feature backported ("-f 522 gcc with the feature backported ("-fstack-protector").
655 523
656 On an x86 "defconfig" build, this fe 524 On an x86 "defconfig" build, this feature adds canary checks to
657 about 3% of all kernel functions, wh 525 about 3% of all kernel functions, which increases kernel code size
658 by about 0.3%. 526 by about 0.3%.
659 527
660 config STACKPROTECTOR_STRONG 528 config STACKPROTECTOR_STRONG
661 bool "Strong Stack Protector" 529 bool "Strong Stack Protector"
662 depends on STACKPROTECTOR 530 depends on STACKPROTECTOR
663 depends on $(cc-option,-fstack-protect 531 depends on $(cc-option,-fstack-protector-strong)
664 default y 532 default y
665 help 533 help
666 Functions will have the stack-protec 534 Functions will have the stack-protector canary logic added in any
667 of the following conditions: 535 of the following conditions:
668 536
669 - local variable's address used as p 537 - local variable's address used as part of the right hand side of an
670 assignment or function argument 538 assignment or function argument
671 - local variable is an array (or uni 539 - local variable is an array (or union containing an array),
672 regardless of array type or length 540 regardless of array type or length
673 - uses register local variables 541 - uses register local variables
674 542
675 This feature requires gcc version 4. 543 This feature requires gcc version 4.9 or above, or a distribution
676 gcc with the feature backported ("-f 544 gcc with the feature backported ("-fstack-protector-strong").
677 545
678 On an x86 "defconfig" build, this fe 546 On an x86 "defconfig" build, this feature adds canary checks to
679 about 20% of all kernel functions, w 547 about 20% of all kernel functions, which increases the kernel code
680 size by about 2%. 548 size by about 2%.
681 549
682 config ARCH_SUPPORTS_SHADOW_CALL_STACK <<
683 bool <<
684 help <<
685 An architecture should select this i <<
686 Shadow Call Stack and implements run <<
687 switching. <<
688 <<
689 config SHADOW_CALL_STACK <<
690 bool "Shadow Call Stack" <<
691 depends on ARCH_SUPPORTS_SHADOW_CALL_S <<
692 depends on DYNAMIC_FTRACE_WITH_ARGS || <<
693 depends on MMU <<
694 help <<
695 This option enables the compiler's S <<
696 uses a shadow stack to protect funct <<
697 being overwritten by an attacker. Mo <<
698 in the compiler's documentation: <<
699 <<
700 - Clang: https://clang.llvm.org/docs <<
701 - GCC: https://gcc.gnu.org/onlinedoc <<
702 <<
703 Note that security guarantees in the <<
704 ones documented for user space. The <<
705 of shadow stacks in memory, which me <<
706 reading and writing arbitrary memory <<
707 and hijack control flow by modifying <<
708 <<
709 config DYNAMIC_SCS <<
710 bool <<
711 help <<
712 Set by the arch code if it relies on <<
713 shadow call stack push and pop instr <<
714 compiler. <<
715 <<
716 config LTO <<
717 bool <<
718 help <<
719 Selected if the kernel will be built <<
720 <<
721 config LTO_CLANG <<
722 bool <<
723 select LTO <<
724 help <<
725 Selected if the kernel will be built <<
726 <<
727 config ARCH_SUPPORTS_LTO_CLANG <<
728 bool <<
729 help <<
730 An architecture should select this o <<
731 - compiling with Clang, <<
732 - compiling inline assembly with Cla <<
733 - and linking with LLD. <<
734 <<
735 config ARCH_SUPPORTS_LTO_CLANG_THIN <<
736 bool <<
737 help <<
738 An architecture should select this o <<
739 ThinLTO mode. <<
740 <<
741 config HAS_LTO_CLANG <<
742 def_bool y <<
743 depends on CC_IS_CLANG && LD_IS_LLD && <<
744 depends on $(success,$(NM) --help | he <<
745 depends on $(success,$(AR) --help | he <<
746 depends on ARCH_SUPPORTS_LTO_CLANG <<
747 depends on !FTRACE_MCOUNT_USE_RECORDMC <<
748 # https://github.com/ClangBuiltLinux/l <<
749 depends on (!KASAN || KASAN_HW_TAGS || <<
750 depends on (!KCOV || CLANG_VERSION >= <<
751 depends on !GCOV_KERNEL <<
752 help <<
753 The compiler and Kconfig options sup <<
754 LTO. <<
755 <<
756 choice <<
757 prompt "Link Time Optimization (LTO)" <<
758 default LTO_NONE <<
759 help <<
760 This option enables Link Time Optimi <<
761 compiler to optimize binaries global <<
762 <<
763 If unsure, select LTO_NONE. Note tha <<
764 so it's disabled by default. <<
765 <<
766 config LTO_NONE <<
767 bool "None" <<
768 help <<
769 Build the kernel normally, without L <<
770 <<
771 config LTO_CLANG_FULL <<
772 bool "Clang Full LTO (EXPERIMENTAL)" <<
773 depends on HAS_LTO_CLANG <<
774 depends on !COMPILE_TEST <<
775 select LTO_CLANG <<
776 help <<
777 This option enables Clang's full Lin <<
778 allows the compiler to optimize the <<
779 this option, the compiler generates <<
780 object files, and the actual compila <<
781 the LTO link step, which may take se <<
782 kernel configuration. More informati <<
783 documentation: <<
784 <<
785 https://llvm.org/docs/LinkTimeOpti <<
786 <<
787 During link time, this option can us <<
788 may take much longer than the ThinLT <<
789 <<
790 config LTO_CLANG_THIN <<
791 bool "Clang ThinLTO (EXPERIMENTAL)" <<
792 depends on HAS_LTO_CLANG && ARCH_SUPPO <<
793 select LTO_CLANG <<
794 help <<
795 This option enables Clang's ThinLTO, <<
796 optimization and faster incremental <<
797 CONFIG_LTO_CLANG_FULL option. More i <<
798 from Clang's documentation: <<
799 <<
800 https://clang.llvm.org/docs/ThinLT <<
801 <<
802 If unsure, say Y. <<
803 endchoice <<
804 <<
805 config ARCH_SUPPORTS_CFI_CLANG <<
806 bool <<
807 help <<
808 An architecture should select this o <<
809 Control-Flow Integrity (CFI) checkin <<
810 <<
811 config ARCH_USES_CFI_TRAPS <<
812 bool <<
813 <<
814 config CFI_CLANG <<
815 bool "Use Clang's Control Flow Integri <<
816 depends on ARCH_SUPPORTS_CFI_CLANG <<
817 depends on $(cc-option,-fsanitize=kcfi <<
818 help <<
819 This option enables Clang's forward- <<
820 (CFI) checking, where the compiler i <<
821 indirect function call to ensure the <<
822 the correct static type. This restri <<
823 makes it more difficult for an attac <<
824 the modification of stored function <<
825 found from Clang's documentation: <<
826 <<
827 https://clang.llvm.org/docs/Contro <<
828 <<
829 config CFI_PERMISSIVE <<
830 bool "Use CFI in permissive mode" <<
831 depends on CFI_CLANG <<
832 help <<
833 When selected, Control Flow Integrit <<
834 warning instead of a kernel panic. T <<
835 for finding indirect call type misma <<
836 <<
837 If unsure, say N. <<
838 <<
839 config HAVE_ARCH_WITHIN_STACK_FRAMES 550 config HAVE_ARCH_WITHIN_STACK_FRAMES
840 bool 551 bool
841 help 552 help
842 An architecture should select this i 553 An architecture should select this if it can walk the kernel stack
843 frames to determine if an object is 554 frames to determine if an object is part of either the arguments
844 or local variables (i.e. that it exc 555 or local variables (i.e. that it excludes saved return addresses,
845 and similar) by implementing an inli 556 and similar) by implementing an inline arch_within_stack_frames(),
846 which is used by CONFIG_HARDENED_USE 557 which is used by CONFIG_HARDENED_USERCOPY.
847 558
848 config HAVE_CONTEXT_TRACKING_USER !! 559 config HAVE_CONTEXT_TRACKING
849 bool 560 bool
850 help 561 help
851 Provide kernel/user boundaries probe 562 Provide kernel/user boundaries probes necessary for subsystems
852 that need it, such as userspace RCU 563 that need it, such as userspace RCU extended quiescent state.
853 Syscalls need to be wrapped inside u !! 564 Syscalls need to be wrapped inside user_exit()-user_enter() through
854 optimized behind static key or throu !! 565 the slow path using TIF_NOHZ flag. Exceptions handlers must be
855 flag. Exceptions handlers must be wr !! 566 wrapped as well. Irqs are already protected inside
856 protected inside ct_irq_enter/ct_irq !! 567 rcu_irq_enter/rcu_irq_exit() but preemption or signal handling on
857 handling on irq exit still need to b !! 568 irq exit still need to be protected.
858 <<
859 config HAVE_CONTEXT_TRACKING_USER_OFFSTACK <<
860 bool <<
861 help <<
862 Architecture neither relies on excep <<
863 nor on schedule_user(). Also preempt <<
864 preempt_schedule_irq() can't be call <<
865 while context tracking is CONTEXT_US <<
866 entry implementation where the follo <<
867 critical entry code, ie: before user <<
868 <<
869 - Critical entry code isn't preempti <<
870 not interruptible). <<
871 - No use of RCU read side critical s <<
872 got called. <<
873 - No use of instrumentation, unless <<
874 called. <<
875 <<
876 config HAVE_TIF_NOHZ <<
877 bool <<
878 help <<
879 Arch relies on TIF_NOHZ and syscall <<
880 tracking calls to user_enter()/user_ <<
881 569
882 config HAVE_VIRT_CPU_ACCOUNTING 570 config HAVE_VIRT_CPU_ACCOUNTING
883 bool 571 bool
884 572
885 config HAVE_VIRT_CPU_ACCOUNTING_IDLE <<
886 bool <<
887 help <<
888 Architecture has its own way to acco <<
889 doesn't implement vtime_account_idle <<
890 <<
891 config ARCH_HAS_SCALED_CPUTIME 573 config ARCH_HAS_SCALED_CPUTIME
892 bool 574 bool
893 575
894 config HAVE_VIRT_CPU_ACCOUNTING_GEN 576 config HAVE_VIRT_CPU_ACCOUNTING_GEN
895 bool 577 bool
896 default y if 64BIT 578 default y if 64BIT
897 help 579 help
898 With VIRT_CPU_ACCOUNTING_GEN, cputim 580 With VIRT_CPU_ACCOUNTING_GEN, cputime_t becomes 64-bit.
899 Before enabling this option, arch co 581 Before enabling this option, arch code must be audited
900 to ensure there are no races in conc 582 to ensure there are no races in concurrent read/write of
901 cputime_t. For example, reading/writ 583 cputime_t. For example, reading/writing 64-bit cputime_t on
902 some 32-bit arches may require multi 584 some 32-bit arches may require multiple accesses, so proper
903 locking is needed to protect against 585 locking is needed to protect against concurrent accesses.
904 586
>> 587
905 config HAVE_IRQ_TIME_ACCOUNTING 588 config HAVE_IRQ_TIME_ACCOUNTING
906 bool 589 bool
907 help 590 help
908 Archs need to ensure they use a high 591 Archs need to ensure they use a high enough resolution clock to
909 support irq time accounting and then 592 support irq time accounting and then call enable_sched_clock_irqtime().
910 593
911 config HAVE_MOVE_PUD <<
912 bool <<
913 help <<
914 Architectures that select this are a <<
915 PUD level. If there are only 3 page <<
916 happens at the PGD level. <<
917 <<
918 config HAVE_MOVE_PMD 594 config HAVE_MOVE_PMD
919 bool 595 bool
920 help 596 help
921 Archs that select this are able to m 597 Archs that select this are able to move page tables at the PMD level.
922 598
923 config HAVE_ARCH_TRANSPARENT_HUGEPAGE 599 config HAVE_ARCH_TRANSPARENT_HUGEPAGE
924 bool 600 bool
925 601
926 config HAVE_ARCH_TRANSPARENT_HUGEPAGE_PUD 602 config HAVE_ARCH_TRANSPARENT_HUGEPAGE_PUD
927 bool 603 bool
928 604
929 config HAVE_ARCH_HUGE_VMAP 605 config HAVE_ARCH_HUGE_VMAP
930 bool 606 bool
931 607
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 608 config ARCH_WANT_HUGE_PMD_SHARE
942 bool 609 bool
943 610
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 611 config HAVE_ARCH_SOFT_DIRTY
953 bool 612 bool
954 613
955 config HAVE_MOD_ARCH_SPECIFIC 614 config HAVE_MOD_ARCH_SPECIFIC
956 bool 615 bool
957 help 616 help
958 The arch uses struct mod_arch_specif 617 The arch uses struct mod_arch_specific to store data. Many arches
959 just need a simple module loader wit 618 just need a simple module loader without arch specific data - those
960 should not enable this. 619 should not enable this.
961 620
962 config MODULES_USE_ELF_RELA 621 config MODULES_USE_ELF_RELA
963 bool 622 bool
964 help 623 help
965 Modules only use ELF RELA relocation 624 Modules only use ELF RELA relocations. Modules with ELF REL
966 relocations will give an error. 625 relocations will give an error.
967 626
968 config MODULES_USE_ELF_REL 627 config MODULES_USE_ELF_REL
969 bool 628 bool
970 help 629 help
971 Modules only use ELF REL relocations 630 Modules only use ELF REL relocations. Modules with ELF RELA
972 relocations will give an error. 631 relocations will give an error.
973 632
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 633 config HAVE_IRQ_EXIT_ON_IRQ_STACK
989 bool 634 bool
990 help 635 help
991 Architecture doesn't only execute th 636 Architecture doesn't only execute the irq handler on the irq stack
992 but also irq_exit(). This way we can 637 but also irq_exit(). This way we can process softirqs on this irq
993 stack instead of switching to a new 638 stack instead of switching to a new one when we call __do_softirq()
994 in the end of an hardirq. 639 in the end of an hardirq.
995 This spares a stack switch and impro 640 This spares a stack switch and improves cache usage on softirq
996 processing. 641 processing.
997 642
998 config HAVE_SOFTIRQ_ON_OWN_STACK <<
999 bool <<
1000 help <<
1001 Architecture provides a function to <<
1002 separate stack. <<
1003 <<
1004 config SOFTIRQ_ON_OWN_STACK <<
1005 def_bool HAVE_SOFTIRQ_ON_OWN_STACK && <<
1006 <<
1007 config ALTERNATE_USER_ADDRESS_SPACE <<
1008 bool <<
1009 help <<
1010 Architectures set this when the CPU <<
1011 spaces for kernel and user space po <<
1012 access_ok() check on a __user point <<
1013 <<
1014 config PGTABLE_LEVELS 643 config PGTABLE_LEVELS
1015 int 644 int
1016 default 2 645 default 2
1017 646
1018 config ARCH_HAS_ELF_RANDOMIZE 647 config ARCH_HAS_ELF_RANDOMIZE
1019 bool 648 bool
1020 help 649 help
1021 An architecture supports choosing r 650 An architecture supports choosing randomized locations for
1022 stack, mmap, brk, and ET_DYN. Defin 651 stack, mmap, brk, and ET_DYN. Defined functions:
1023 - arch_mmap_rnd() 652 - arch_mmap_rnd()
1024 - arch_randomize_brk() 653 - arch_randomize_brk()
1025 654
1026 config HAVE_ARCH_MMAP_RND_BITS 655 config HAVE_ARCH_MMAP_RND_BITS
1027 bool 656 bool
1028 help 657 help
1029 An arch should select this symbol i 658 An arch should select this symbol if it supports setting a variable
1030 number of bits for use in establish 659 number of bits for use in establishing the base address for mmap
1031 allocations, has MMU enabled and pr 660 allocations, has MMU enabled and provides values for both:
1032 - ARCH_MMAP_RND_BITS_MIN 661 - ARCH_MMAP_RND_BITS_MIN
1033 - ARCH_MMAP_RND_BITS_MAX 662 - ARCH_MMAP_RND_BITS_MAX
1034 663
1035 config HAVE_EXIT_THREAD 664 config HAVE_EXIT_THREAD
1036 bool 665 bool
1037 help 666 help
1038 An architecture implements exit_thr 667 An architecture implements exit_thread.
1039 668
1040 config ARCH_MMAP_RND_BITS_MIN 669 config ARCH_MMAP_RND_BITS_MIN
1041 int 670 int
1042 671
1043 config ARCH_MMAP_RND_BITS_MAX 672 config ARCH_MMAP_RND_BITS_MAX
1044 int 673 int
1045 674
1046 config ARCH_MMAP_RND_BITS_DEFAULT 675 config ARCH_MMAP_RND_BITS_DEFAULT
1047 int 676 int
1048 677
1049 config ARCH_MMAP_RND_BITS 678 config ARCH_MMAP_RND_BITS
1050 int "Number of bits to use for ASLR o 679 int "Number of bits to use for ASLR of mmap base address" if EXPERT
1051 range ARCH_MMAP_RND_BITS_MIN ARCH_MMA 680 range ARCH_MMAP_RND_BITS_MIN ARCH_MMAP_RND_BITS_MAX
1052 default ARCH_MMAP_RND_BITS_DEFAULT if 681 default ARCH_MMAP_RND_BITS_DEFAULT if ARCH_MMAP_RND_BITS_DEFAULT
1053 default ARCH_MMAP_RND_BITS_MIN 682 default ARCH_MMAP_RND_BITS_MIN
1054 depends on HAVE_ARCH_MMAP_RND_BITS 683 depends on HAVE_ARCH_MMAP_RND_BITS
1055 help 684 help
1056 This value can be used to select th 685 This value can be used to select the number of bits to use to
1057 determine the random offset to the 686 determine the random offset to the base address of vma regions
1058 resulting from mmap allocations. Th 687 resulting from mmap allocations. This value will be bounded
1059 by the architecture's minimum and m 688 by the architecture's minimum and maximum supported values.
1060 689
1061 This value can be changed after boo 690 This value can be changed after boot using the
1062 /proc/sys/vm/mmap_rnd_bits tunable 691 /proc/sys/vm/mmap_rnd_bits tunable
1063 692
1064 config HAVE_ARCH_MMAP_RND_COMPAT_BITS 693 config HAVE_ARCH_MMAP_RND_COMPAT_BITS
1065 bool 694 bool
1066 help 695 help
1067 An arch should select this symbol i 696 An arch should select this symbol if it supports running applications
1068 in compatibility mode, supports set 697 in compatibility mode, supports setting a variable number of bits for
1069 use in establishing the base addres 698 use in establishing the base address for mmap allocations, has MMU
1070 enabled and provides values for bot 699 enabled and provides values for both:
1071 - ARCH_MMAP_RND_COMPAT_BITS_MIN 700 - ARCH_MMAP_RND_COMPAT_BITS_MIN
1072 - ARCH_MMAP_RND_COMPAT_BITS_MAX 701 - ARCH_MMAP_RND_COMPAT_BITS_MAX
1073 702
1074 config ARCH_MMAP_RND_COMPAT_BITS_MIN 703 config ARCH_MMAP_RND_COMPAT_BITS_MIN
1075 int 704 int
1076 705
1077 config ARCH_MMAP_RND_COMPAT_BITS_MAX 706 config ARCH_MMAP_RND_COMPAT_BITS_MAX
1078 int 707 int
1079 708
1080 config ARCH_MMAP_RND_COMPAT_BITS_DEFAULT 709 config ARCH_MMAP_RND_COMPAT_BITS_DEFAULT
1081 int 710 int
1082 711
1083 config ARCH_MMAP_RND_COMPAT_BITS 712 config ARCH_MMAP_RND_COMPAT_BITS
1084 int "Number of bits to use for ASLR o 713 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 714 range ARCH_MMAP_RND_COMPAT_BITS_MIN ARCH_MMAP_RND_COMPAT_BITS_MAX
1086 default ARCH_MMAP_RND_COMPAT_BITS_DEF 715 default ARCH_MMAP_RND_COMPAT_BITS_DEFAULT if ARCH_MMAP_RND_COMPAT_BITS_DEFAULT
1087 default ARCH_MMAP_RND_COMPAT_BITS_MIN 716 default ARCH_MMAP_RND_COMPAT_BITS_MIN
1088 depends on HAVE_ARCH_MMAP_RND_COMPAT_ 717 depends on HAVE_ARCH_MMAP_RND_COMPAT_BITS
1089 help 718 help
1090 This value can be used to select th 719 This value can be used to select the number of bits to use to
1091 determine the random offset to the 720 determine the random offset to the base address of vma regions
1092 resulting from mmap allocations for 721 resulting from mmap allocations for compatible applications This
1093 value will be bounded by the archit 722 value will be bounded by the architecture's minimum and maximum
1094 supported values. 723 supported values.
1095 724
1096 This value can be changed after boo 725 This value can be changed after boot using the
1097 /proc/sys/vm/mmap_rnd_compat_bits t 726 /proc/sys/vm/mmap_rnd_compat_bits tunable
1098 727
1099 config HAVE_ARCH_COMPAT_MMAP_BASES 728 config HAVE_ARCH_COMPAT_MMAP_BASES
1100 bool 729 bool
1101 help 730 help
1102 This allows 64bit applications to i 731 This allows 64bit applications to invoke 32-bit mmap() syscall
1103 and vice-versa 32-bit applications 732 and vice-versa 32-bit applications to call 64-bit mmap().
1104 Required for applications doing dif 733 Required for applications doing different bitness syscalls.
1105 734
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 735 # This allows to use a set of generic functions to determine mmap base
1208 # address by giving priority to top-down sche 736 # address by giving priority to top-down scheme only if the process
1209 # is not in legacy mode (compat task, unlimit 737 # is not in legacy mode (compat task, unlimited stack size or
1210 # sysctl_legacy_va_layout). 738 # sysctl_legacy_va_layout).
1211 # Architecture that selects this option can p 739 # Architecture that selects this option can provide its own version of:
1212 # - STACK_RND_MASK 740 # - STACK_RND_MASK
1213 config ARCH_WANT_DEFAULT_TOPDOWN_MMAP_LAYOUT 741 config ARCH_WANT_DEFAULT_TOPDOWN_MMAP_LAYOUT
1214 bool 742 bool
1215 depends on MMU 743 depends on MMU
1216 select ARCH_HAS_ELF_RANDOMIZE 744 select ARCH_HAS_ELF_RANDOMIZE
1217 745
1218 config HAVE_OBJTOOL !! 746 config HAVE_COPY_THREAD_TLS
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 747 bool
1232 select OBJTOOL !! 748 help
>> 749 Architecture provides copy_thread_tls to accept tls argument via
>> 750 normal C parameter passing, rather than extracting the syscall
>> 751 argument from pt_regs.
1233 752
1234 config HAVE_STACK_VALIDATION 753 config HAVE_STACK_VALIDATION
1235 bool 754 bool
1236 help 755 help
1237 Architecture supports objtool compi !! 756 Architecture supports the 'objtool check' host tool command, which
1238 validation. !! 757 performs compile-time stack metadata validation.
1239 758
1240 config HAVE_RELIABLE_STACKTRACE 759 config HAVE_RELIABLE_STACKTRACE
1241 bool 760 bool
1242 help 761 help
1243 Architecture has either save_stack_ !! 762 Architecture has a save_stack_trace_tsk_reliable() function which
1244 arch_stack_walk_reliable() function !! 763 only returns a stack trace if it can guarantee the trace is reliable.
1245 if it can guarantee the trace is re <<
1246 764
1247 config HAVE_ARCH_HASH 765 config HAVE_ARCH_HASH
1248 bool 766 bool
1249 default n 767 default n
1250 help 768 help
1251 If this is set, the architecture pr 769 If this is set, the architecture provides an <asm/hash.h>
1252 file which provides platform-specif 770 file which provides platform-specific implementations of some
1253 functions in <linux/hash.h> or fs/n 771 functions in <linux/hash.h> or fs/namei.c.
1254 772
1255 config HAVE_ARCH_NVRAM_OPS 773 config HAVE_ARCH_NVRAM_OPS
1256 bool 774 bool
1257 775
1258 config ISA_BUS_API 776 config ISA_BUS_API
1259 def_bool ISA 777 def_bool ISA
1260 778
1261 # 779 #
1262 # ABI hall of shame 780 # ABI hall of shame
1263 # 781 #
1264 config CLONE_BACKWARDS 782 config CLONE_BACKWARDS
1265 bool 783 bool
1266 help 784 help
1267 Architecture has tls passed as the 785 Architecture has tls passed as the 4th argument of clone(2),
1268 not the 5th one. 786 not the 5th one.
1269 787
1270 config CLONE_BACKWARDS2 788 config CLONE_BACKWARDS2
1271 bool 789 bool
1272 help 790 help
1273 Architecture has the first two argu 791 Architecture has the first two arguments of clone(2) swapped.
1274 792
1275 config CLONE_BACKWARDS3 793 config CLONE_BACKWARDS3
1276 bool 794 bool
1277 help 795 help
1278 Architecture has tls passed as the 796 Architecture has tls passed as the 3rd argument of clone(2),
1279 not the 5th one. 797 not the 5th one.
1280 798
1281 config ODD_RT_SIGACTION 799 config ODD_RT_SIGACTION
1282 bool 800 bool
1283 help 801 help
1284 Architecture has unusual rt_sigacti 802 Architecture has unusual rt_sigaction(2) arguments
1285 803
1286 config OLD_SIGSUSPEND 804 config OLD_SIGSUSPEND
1287 bool 805 bool
1288 help 806 help
1289 Architecture has old sigsuspend(2) 807 Architecture has old sigsuspend(2) syscall, of one-argument variety
1290 808
1291 config OLD_SIGSUSPEND3 809 config OLD_SIGSUSPEND3
1292 bool 810 bool
1293 help 811 help
1294 Even weirder antique ABI - three-ar 812 Even weirder antique ABI - three-argument sigsuspend(2)
1295 813
1296 config OLD_SIGACTION 814 config OLD_SIGACTION
1297 bool 815 bool
1298 help 816 help
1299 Architecture has old sigaction(2) s 817 Architecture has old sigaction(2) syscall. Nope, not the same
1300 as OLD_SIGSUSPEND | OLD_SIGSUSPEND3 818 as OLD_SIGSUSPEND | OLD_SIGSUSPEND3 - alpha has sigsuspend(2),
1301 but fairly different variant of sig 819 but fairly different variant of sigaction(2), thanks to OSF/1
1302 compatibility... 820 compatibility...
1303 821
1304 config COMPAT_OLD_SIGACTION 822 config COMPAT_OLD_SIGACTION
1305 bool 823 bool
1306 824
>> 825 config 64BIT_TIME
>> 826 def_bool y
>> 827 help
>> 828 This should be selected by all architectures that need to support
>> 829 new system calls with a 64-bit time_t. This is relevant on all 32-bit
>> 830 architectures, and 64-bit architectures as part of compat syscall
>> 831 handling.
>> 832
1307 config COMPAT_32BIT_TIME 833 config COMPAT_32BIT_TIME
1308 bool "Provide system calls for 32-bit !! 834 def_bool !64BIT || COMPAT
1309 default !64BIT || COMPAT <<
1310 help 835 help
1311 This enables 32 bit time_t support 836 This enables 32 bit time_t support in addition to 64 bit time_t support.
1312 This is relevant on all 32-bit arch 837 This is relevant on all 32-bit architectures, and 64-bit architectures
1313 as part of compat syscall handling. 838 as part of compat syscall handling.
1314 839
1315 config ARCH_NO_PREEMPT 840 config ARCH_NO_PREEMPT
1316 bool 841 bool
1317 842
1318 config ARCH_SUPPORTS_RT 843 config ARCH_SUPPORTS_RT
1319 bool 844 bool
1320 845
1321 config CPU_NO_EFFICIENT_FFS 846 config CPU_NO_EFFICIENT_FFS
1322 def_bool n 847 def_bool n
1323 848
1324 config HAVE_ARCH_VMAP_STACK 849 config HAVE_ARCH_VMAP_STACK
1325 def_bool n 850 def_bool n
1326 help 851 help
1327 An arch should select this symbol i 852 An arch should select this symbol if it can support kernel stacks
1328 in vmalloc space. This means: 853 in vmalloc space. This means:
1329 854
1330 - vmalloc space must be large enoug 855 - vmalloc space must be large enough to hold many kernel stacks.
1331 This may rule out many 32-bit arc 856 This may rule out many 32-bit architectures.
1332 857
1333 - Stacks in vmalloc space need to w 858 - Stacks in vmalloc space need to work reliably. For example, if
1334 vmap page tables are created on d 859 vmap page tables are created on demand, either this mechanism
1335 needs to work while the stack poi 860 needs to work while the stack points to a virtual address with
1336 unpopulated page tables or arch c 861 unpopulated page tables or arch code (switch_to() and switch_mm(),
1337 most likely) needs to ensure that 862 most likely) needs to ensure that the stack's page table entries
1338 are populated before running on a 863 are populated before running on a possibly unpopulated stack.
1339 864
1340 - If the stack overflows into a gua 865 - If the stack overflows into a guard page, something reasonable
1341 should happen. The definition of 866 should happen. The definition of "reasonable" is flexible, but
1342 instantly rebooting without loggi 867 instantly rebooting without logging anything would be unfriendly.
1343 868
1344 config VMAP_STACK 869 config VMAP_STACK
1345 default y 870 default y
1346 bool "Use a virtually-mapped stack" 871 bool "Use a virtually-mapped stack"
1347 depends on HAVE_ARCH_VMAP_STACK !! 872 depends on HAVE_ARCH_VMAP_STACK && !KASAN
1348 depends on !KASAN || KASAN_HW_TAGS || !! 873 ---help---
1349 help <<
1350 Enable this if you want the use vir 874 Enable this if you want the use virtually-mapped kernel stacks
1351 with guard pages. This causes kern 875 with guard pages. This causes kernel stack overflows to be
1352 caught immediately rather than caus 876 caught immediately rather than causing difficult-to-diagnose
1353 corruption. 877 corruption.
1354 878
1355 To use this with software KASAN mod !! 879 This is presently incompatible with KASAN because KASAN expects
1356 backing virtual mappings with real !! 880 the stack to map directly to the KASAN shadow map using a formula
1357 must be enabled. !! 881 that is incorrect if the stack is in vmalloc space.
1358 <<
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 882
1396 config ARCH_OPTIONAL_KERNEL_RWX 883 config ARCH_OPTIONAL_KERNEL_RWX
1397 def_bool n 884 def_bool n
1398 885
1399 config ARCH_OPTIONAL_KERNEL_RWX_DEFAULT 886 config ARCH_OPTIONAL_KERNEL_RWX_DEFAULT
1400 def_bool n 887 def_bool n
1401 888
1402 config ARCH_HAS_STRICT_KERNEL_RWX 889 config ARCH_HAS_STRICT_KERNEL_RWX
1403 def_bool n 890 def_bool n
1404 891
1405 config STRICT_KERNEL_RWX 892 config STRICT_KERNEL_RWX
1406 bool "Make kernel text and rodata rea 893 bool "Make kernel text and rodata read-only" if ARCH_OPTIONAL_KERNEL_RWX
1407 depends on ARCH_HAS_STRICT_KERNEL_RWX 894 depends on ARCH_HAS_STRICT_KERNEL_RWX
1408 default !ARCH_OPTIONAL_KERNEL_RWX || 895 default !ARCH_OPTIONAL_KERNEL_RWX || ARCH_OPTIONAL_KERNEL_RWX_DEFAULT
1409 help 896 help
1410 If this is set, kernel text and rod 897 If this is set, kernel text and rodata memory will be made read-only,
1411 and non-text memory will be made no 898 and non-text memory will be made non-executable. This provides
1412 protection against certain security 899 protection against certain security exploits (e.g. executing the heap
1413 or modifying text) 900 or modifying text)
1414 901
1415 These features are considered stand 902 These features are considered standard security practice these days.
1416 You should say Y here in almost all 903 You should say Y here in almost all cases.
1417 904
1418 config ARCH_HAS_STRICT_MODULE_RWX 905 config ARCH_HAS_STRICT_MODULE_RWX
1419 def_bool n 906 def_bool n
1420 907
1421 config STRICT_MODULE_RWX 908 config STRICT_MODULE_RWX
1422 bool "Set loadable kernel module data 909 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 910 depends on ARCH_HAS_STRICT_MODULE_RWX && MODULES
1424 default !ARCH_OPTIONAL_KERNEL_RWX || 911 default !ARCH_OPTIONAL_KERNEL_RWX || ARCH_OPTIONAL_KERNEL_RWX_DEFAULT
1425 help 912 help
1426 If this is set, module text and rod 913 If this is set, module text and rodata memory will be made read-only,
1427 and non-text memory will be made no 914 and non-text memory will be made non-executable. This provides
1428 protection against certain security 915 protection against certain security exploits (e.g. writing to text)
1429 916
1430 # select if the architecture provides an asm/ 917 # select if the architecture provides an asm/dma-direct.h header
1431 config ARCH_HAS_PHYS_TO_DMA 918 config ARCH_HAS_PHYS_TO_DMA
1432 bool 919 bool
1433 920
1434 config HAVE_ARCH_COMPILER_H 921 config HAVE_ARCH_COMPILER_H
1435 bool 922 bool
1436 help 923 help
1437 An architecture can select this if 924 An architecture can select this if it provides an
1438 asm/compiler.h header that should b 925 asm/compiler.h header that should be included after
1439 linux/compiler-*.h in order to over 926 linux/compiler-*.h in order to override macro definitions that those
1440 headers generally provide. 927 headers generally provide.
1441 928
1442 config HAVE_ARCH_PREL32_RELOCATIONS 929 config HAVE_ARCH_PREL32_RELOCATIONS
1443 bool 930 bool
1444 help 931 help
1445 May be selected by an architecture 932 May be selected by an architecture if it supports place-relative
1446 32-bit relocations, both in the too 933 32-bit relocations, both in the toolchain and in the module loader,
1447 in which case relative references c 934 in which case relative references can be used in special sections
1448 for PCI fixup, initcalls etc which 935 for PCI fixup, initcalls etc which are only half the size on 64 bit
1449 architectures, and don't require ru 936 architectures, and don't require runtime relocation on relocatable
1450 kernels. 937 kernels.
1451 938
1452 config ARCH_USE_MEMREMAP_PROT 939 config ARCH_USE_MEMREMAP_PROT
1453 bool 940 bool
1454 941
1455 config LOCK_EVENT_COUNTS 942 config LOCK_EVENT_COUNTS
1456 bool "Locking event counts collection 943 bool "Locking event counts collection"
1457 depends on DEBUG_FS 944 depends on DEBUG_FS
1458 help !! 945 ---help---
1459 Enable light-weight counting of var 946 Enable light-weight counting of various locking related events
1460 in the system with minimal performa 947 in the system with minimal performance impact. This reduces
1461 the chance of application behavior 948 the chance of application behavior change because of timing
1462 differences. The counts are reporte 949 differences. The counts are reported via debugfs.
1463 950
1464 # Select if the architecture has support for 951 # Select if the architecture has support for applying RELR relocations.
1465 config ARCH_HAS_RELR 952 config ARCH_HAS_RELR
1466 bool 953 bool
1467 954
1468 config RELR 955 config RELR
1469 bool "Use RELR relocation packing" 956 bool "Use RELR relocation packing"
1470 depends on ARCH_HAS_RELR && TOOLS_SUP 957 depends on ARCH_HAS_RELR && TOOLS_SUPPORT_RELR
1471 default y 958 default y
1472 help 959 help
1473 Store the kernel's dynamic relocati 960 Store the kernel's dynamic relocations in the RELR relocation packing
1474 format. Requires a compatible linke 961 format. Requires a compatible linker (LLD supports this feature), as
1475 well as compatible NM and OBJCOPY u 962 well as compatible NM and OBJCOPY utilities (llvm-nm and llvm-objcopy
1476 are compatible). 963 are compatible).
1477 964
1478 config ARCH_HAS_MEM_ENCRYPT 965 config ARCH_HAS_MEM_ENCRYPT
1479 bool 966 bool
1480 967
1481 config ARCH_HAS_CC_PLATFORM <<
1482 bool <<
1483 <<
1484 config HAVE_SPARSE_SYSCALL_NR <<
1485 bool <<
1486 help <<
1487 An architecture should select this <<
1488 to save space. For example, MIPS ar <<
1489 entries at 4000, 5000 and 6000 loca <<
1490 related optimizations for a given a <<
1491 <<
1492 config ARCH_HAS_VDSO_DATA <<
1493 bool <<
1494 <<
1495 config HAVE_STATIC_CALL <<
1496 bool <<
1497 <<
1498 config HAVE_STATIC_CALL_INLINE <<
1499 bool <<
1500 depends on HAVE_STATIC_CALL <<
1501 select OBJTOOL <<
1502 <<
1503 config HAVE_PREEMPT_DYNAMIC <<
1504 bool <<
1505 <<
1506 config HAVE_PREEMPT_DYNAMIC_CALL <<
1507 bool <<
1508 depends on HAVE_STATIC_CALL <<
1509 select HAVE_PREEMPT_DYNAMIC <<
1510 help <<
1511 An architecture should select this <<
1512 model being selected at boot time u <<
1513 <<
1514 Where an architecture selects HAVE_ <<
1515 preemption function will be patched <<
1516 <<
1517 Where an architecture does not sele <<
1518 call to a preemption function will <<
1519 trampoline will be patched. <<
1520 <<
1521 It is strongly advised to support i <<
1522 overhead. <<
1523 <<
1524 config HAVE_PREEMPT_DYNAMIC_KEY <<
1525 bool <<
1526 depends on HAVE_ARCH_JUMP_LABEL <<
1527 select HAVE_PREEMPT_DYNAMIC <<
1528 help <<
1529 An architecture should select this <<
1530 model being selected at boot time u <<
1531 <<
1532 Each preemption function will be gi <<
1533 static key. This should have slight <<
1534 static calls, as this effectively i <<
1535 start of its callee. This may avoid <<
1536 integrate better with CFI schemes. <<
1537 <<
1538 This will have greater overhead tha <<
1539 the call to the preemption function <<
1540 <<
1541 config ARCH_WANT_LD_ORPHAN_WARN <<
1542 bool <<
1543 help <<
1544 An arch should select this symbol o <<
1545 included, size-asserted, or discard <<
1546 important because we never want exp <<
1547 by the linker, since the locations <<
1548 versions. <<
1549 <<
1550 config HAVE_ARCH_PFN_VALID <<
1551 bool <<
1552 <<
1553 config ARCH_SUPPORTS_DEBUG_PAGEALLOC <<
1554 bool <<
1555 <<
1556 config ARCH_SUPPORTS_PAGE_TABLE_CHECK <<
1557 bool <<
1558 <<
1559 config ARCH_SPLIT_ARG64 <<
1560 bool <<
1561 help <<
1562 If a 32-bit architecture requires 6 <<
1563 pairs of 32-bit arguments, select t <<
1564 <<
1565 config ARCH_HAS_ELFCORE_COMPAT <<
1566 bool <<
1567 <<
1568 config ARCH_HAS_PARANOID_L1D_FLUSH <<
1569 bool <<
1570 <<
1571 config ARCH_HAVE_TRACE_MMIO_ACCESS <<
1572 bool <<
1573 <<
1574 config DYNAMIC_SIGFRAME <<
1575 bool <<
1576 <<
1577 # Select, if arch has a named attribute group <<
1578 config HAVE_ARCH_NODE_DEV_GROUP <<
1579 bool <<
1580 <<
1581 config ARCH_HAS_HW_PTE_YOUNG <<
1582 bool <<
1583 help <<
1584 Architectures that select this opti <<
1585 accessed bit in PTE entries when us <<
1586 translations. Architectures that re <<
1587 this option and override arch_has_h <<
1588 <<
1589 config ARCH_HAS_NONLEAF_PMD_YOUNG <<
1590 bool <<
1591 help <<
1592 Architectures that select this opti <<
1593 accessed bit in non-leaf PMD entrie <<
1594 address translations. Page table wa <<
1595 may use this capability to reduce t <<
1596 <<
1597 config ARCH_HAS_KERNEL_FPU_SUPPORT <<
1598 bool <<
1599 help <<
1600 Architectures that select this opti <<
1601 the kernel, as described in Documen <<
1602 <<
1603 source "kernel/gcov/Kconfig" 968 source "kernel/gcov/Kconfig"
1604 969
1605 source "scripts/gcc-plugins/Kconfig" 970 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 971
1646 endmenu 972 endmenu
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