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 HAVE_IMA_KEXEC
33 bool 22 bool
34 23
35 # Selected by HOTPLUG_CORE_SYNC_DEAD or HOTPLU !! 24 config HOTPLUG_SMT
36 config HOTPLUG_CORE_SYNC <<
37 bool 25 bool
38 26
39 # Basic CPU dead synchronization selected by a !! 27 config OPROFILE
40 config HOTPLUG_CORE_SYNC_DEAD !! 28 tristate "OProfile system profiling"
41 bool !! 29 depends on PROFILING
42 select HOTPLUG_CORE_SYNC !! 30 depends on HAVE_OPROFILE
>> 31 select RING_BUFFER
>> 32 select RING_BUFFER_ALLOW_SWAP
>> 33 help
>> 34 OProfile is a profiling system capable of profiling the
>> 35 whole system, include the kernel, kernel modules, libraries,
>> 36 and applications.
43 37
44 # Full CPU synchronization with alive state se !! 38 If unsure, say N.
45 config HOTPLUG_CORE_SYNC_FULL <<
46 bool <<
47 select HOTPLUG_CORE_SYNC_DEAD if HOTPL <<
48 select HOTPLUG_CORE_SYNC <<
49 39
50 config HOTPLUG_SPLIT_STARTUP !! 40 config OPROFILE_EVENT_MULTIPLEX
51 bool !! 41 bool "OProfile multiplexing support (EXPERIMENTAL)"
52 select HOTPLUG_CORE_SYNC_FULL !! 42 default n
>> 43 depends on OPROFILE && X86
>> 44 help
>> 45 The number of hardware counters is limited. The multiplexing
>> 46 feature enables OProfile to gather more events than counters
>> 47 are provided by the hardware. This is realized by switching
>> 48 between events at a user specified time interval.
53 49
54 config HOTPLUG_PARALLEL !! 50 If unsure, say N.
55 bool <<
56 select HOTPLUG_SPLIT_STARTUP <<
57 51
58 config GENERIC_ENTRY !! 52 config HAVE_OPROFILE
59 bool 53 bool
60 54
>> 55 config OPROFILE_NMI_TIMER
>> 56 def_bool y
>> 57 depends on PERF_EVENTS && HAVE_PERF_EVENTS_NMI && !PPC64
>> 58
61 config KPROBES 59 config KPROBES
62 bool "Kprobes" 60 bool "Kprobes"
>> 61 depends on MODULES
63 depends on HAVE_KPROBES 62 depends on HAVE_KPROBES
64 select KALLSYMS 63 select KALLSYMS
65 select EXECMEM <<
66 select NEED_TASKS_RCU <<
67 help 64 help
68 Kprobes allows you to trap at almost 65 Kprobes allows you to trap at almost any kernel address and
69 execute a callback function. regist 66 execute a callback function. register_kprobe() establishes
70 a probepoint and specifies the callb 67 a probepoint and specifies the callback. Kprobes is useful
71 for kernel debugging, non-intrusive 68 for kernel debugging, non-intrusive instrumentation and testing.
72 If in doubt, say "N". 69 If in doubt, say "N".
73 70
74 config JUMP_LABEL 71 config JUMP_LABEL
75 bool "Optimize very unlikely/likely br !! 72 bool "Optimize very unlikely/likely branches"
76 depends on HAVE_ARCH_JUMP_LABEL !! 73 depends on HAVE_ARCH_JUMP_LABEL
77 select OBJTOOL if HAVE_JUMP_LABEL_HACK !! 74 depends on CC_HAS_ASM_GOTO
78 help !! 75 help
79 This option enables a transparent br !! 76 This option enables a transparent branch optimization that
80 makes certain almost-always-true or !! 77 makes certain almost-always-true or almost-always-false branch
81 conditions even cheaper to execute w !! 78 conditions even cheaper to execute within the kernel.
82 !! 79
83 Certain performance-sensitive kernel !! 80 Certain performance-sensitive kernel code, such as trace points,
84 scheduler functionality, networking !! 81 scheduler functionality, networking code and KVM have such
85 branches and include support for thi !! 82 branches and include support for this optimization technique.
86 !! 83
87 If it is detected that the compiler !! 84 If it is detected that the compiler has support for "asm goto",
88 the kernel will compile such branche !! 85 the kernel will compile such branches with just a nop
89 instruction. When the condition flag !! 86 instruction. When the condition flag is toggled to true, the
90 nop will be converted to a jump inst !! 87 nop will be converted to a jump instruction to execute the
91 conditional block of instructions. !! 88 conditional block of instructions.
92 !! 89
93 This technique lowers overhead and s !! 90 This technique lowers overhead and stress on the branch prediction
94 of the processor and generally makes !! 91 of the processor and generally makes the kernel faster. The update
95 of the condition is slower, but thos !! 92 of the condition is slower, but those are always very rare.
96 93
97 ( On 32-bit x86, the necessary optio !! 94 ( On 32-bit x86, the necessary options added to the compiler
98 flags may increase the size of the !! 95 flags may increase the size of the kernel slightly. )
99 96
100 config STATIC_KEYS_SELFTEST 97 config STATIC_KEYS_SELFTEST
101 bool "Static key selftest" 98 bool "Static key selftest"
102 depends on JUMP_LABEL 99 depends on JUMP_LABEL
103 help 100 help
104 Boot time self-test of the branch pa 101 Boot time self-test of the branch patching code.
105 102
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 103 config OPTPROBES
113 def_bool y 104 def_bool y
114 depends on KPROBES && HAVE_OPTPROBES 105 depends on KPROBES && HAVE_OPTPROBES
115 select NEED_TASKS_RCU !! 106 select TASKS_RCU if PREEMPT
116 107
117 config KPROBES_ON_FTRACE 108 config KPROBES_ON_FTRACE
118 def_bool y 109 def_bool y
119 depends on KPROBES && HAVE_KPROBES_ON_ 110 depends on KPROBES && HAVE_KPROBES_ON_FTRACE
120 depends on DYNAMIC_FTRACE_WITH_REGS 111 depends on DYNAMIC_FTRACE_WITH_REGS
121 help 112 help
122 If function tracer is enabled and th !! 113 If function tracer is enabled and the arch supports full
123 passing of pt_regs to function traci !! 114 passing of pt_regs to function tracing, then kprobes can
124 optimize on top of function tracing. !! 115 optimize on top of function tracing.
125 116
126 config UPROBES 117 config UPROBES
127 def_bool n 118 def_bool n
128 depends on ARCH_SUPPORTS_UPROBES 119 depends on ARCH_SUPPORTS_UPROBES
129 help 120 help
130 Uprobes is the user-space counterpar 121 Uprobes is the user-space counterpart to kprobes: they
131 enable instrumentation applications 122 enable instrumentation applications (such as 'perf probe')
132 to establish unintrusive probes in u 123 to establish unintrusive probes in user-space binaries and
133 libraries, by executing handler func 124 libraries, by executing handler functions when the probes
134 are hit by user-space applications. 125 are hit by user-space applications.
135 126
136 ( These probes come in the form of s 127 ( These probes come in the form of single-byte breakpoints,
137 managed by the kernel and kept tra 128 managed by the kernel and kept transparent to the probed
138 application. ) 129 application. )
139 130
140 config HAVE_64BIT_ALIGNED_ACCESS 131 config HAVE_64BIT_ALIGNED_ACCESS
141 def_bool 64BIT && !HAVE_EFFICIENT_UNAL 132 def_bool 64BIT && !HAVE_EFFICIENT_UNALIGNED_ACCESS
142 help 133 help
143 Some architectures require 64 bit ac 134 Some architectures require 64 bit accesses to be 64 bit
144 aligned, which also requires structs 135 aligned, which also requires structs containing 64 bit values
145 to be 64 bit aligned too. This inclu 136 to be 64 bit aligned too. This includes some 32 bit
146 architectures which can do 64 bit ac 137 architectures which can do 64 bit accesses, as well as 64 bit
147 architectures without unaligned acce 138 architectures without unaligned access.
148 139
149 This symbol should be selected by an 140 This symbol should be selected by an architecture if 64 bit
150 accesses are required to be 64 bit a 141 accesses are required to be 64 bit aligned in this way even
151 though it is not a 64 bit architectu 142 though it is not a 64 bit architecture.
152 143
153 See Documentation/core-api/unaligned !! 144 See Documentation/unaligned-memory-access.txt for more
154 more information on the topic of una !! 145 information on the topic of unaligned memory accesses.
155 146
156 config HAVE_EFFICIENT_UNALIGNED_ACCESS 147 config HAVE_EFFICIENT_UNALIGNED_ACCESS
157 bool 148 bool
158 help 149 help
159 Some architectures are unable to per 150 Some architectures are unable to perform unaligned accesses
160 without the use of get_unaligned/put 151 without the use of get_unaligned/put_unaligned. Others are
161 unable to perform such accesses effi 152 unable to perform such accesses efficiently (e.g. trap on
162 unaligned access and require fixing 153 unaligned access and require fixing it up in the exception
163 handler.) 154 handler.)
164 155
165 This symbol should be selected by an 156 This symbol should be selected by an architecture if it can
166 perform unaligned accesses efficient 157 perform unaligned accesses efficiently to allow different
167 code paths to be selected for these 158 code paths to be selected for these cases. Some network
168 drivers, for example, could opt to n 159 drivers, for example, could opt to not fix up alignment
169 problems with received packets if do 160 problems with received packets if doing so would not help
170 much. 161 much.
171 162
172 See Documentation/core-api/unaligned !! 163 See Documentation/unaligned-memory-access.txt for more
173 information on the topic of unaligne 164 information on the topic of unaligned memory accesses.
174 165
175 config ARCH_USE_BUILTIN_BSWAP 166 config ARCH_USE_BUILTIN_BSWAP
176 bool !! 167 bool
177 help !! 168 help
178 Modern versions of GCC (since 4.4) h !! 169 Modern versions of GCC (since 4.4) have builtin functions
179 for handling byte-swapping. Using th !! 170 for handling byte-swapping. Using these, instead of the old
180 inline assembler that the architectu !! 171 inline assembler that the architecture code provides in the
181 __arch_bswapXX() macros, allows the !! 172 __arch_bswapXX() macros, allows the compiler to see what's
182 happening and offers more opportunit !! 173 happening and offers more opportunity for optimisation. In
183 particular, the compiler will be abl !! 174 particular, the compiler will be able to combine the byteswap
184 with a nearby load or store and use !! 175 with a nearby load or store and use load-and-swap or
185 store-and-swap instructions if the a !! 176 store-and-swap instructions if the architecture has them. It
186 should almost *never* result in code !! 177 should almost *never* result in code which is worse than the
187 hand-coded assembler in <asm/swab.h> !! 178 hand-coded assembler in <asm/swab.h>. But just in case it
188 does, the use of the builtins is opt !! 179 does, the use of the builtins is optional.
189 !! 180
190 Any architecture with load-and-swap !! 181 Any architecture with load-and-swap or store-and-swap
191 instructions should set this. And it !! 182 instructions should set this. And it shouldn't hurt to set it
192 on architectures that don't have suc !! 183 on architectures that don't have such instructions.
193 184
194 config KRETPROBES 185 config KRETPROBES
195 def_bool y 186 def_bool y
196 depends on KPROBES && (HAVE_KRETPROBES !! 187 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 <<
203 188
204 config USER_RETURN_NOTIFIER 189 config USER_RETURN_NOTIFIER
205 bool 190 bool
206 depends on HAVE_USER_RETURN_NOTIFIER 191 depends on HAVE_USER_RETURN_NOTIFIER
207 help 192 help
208 Provide a kernel-internal notificati 193 Provide a kernel-internal notification when a cpu is about to
209 switch to user mode. 194 switch to user mode.
210 195
211 config HAVE_IOREMAP_PROT 196 config HAVE_IOREMAP_PROT
212 bool 197 bool
213 198
214 config HAVE_KPROBES 199 config HAVE_KPROBES
215 bool 200 bool
216 201
217 config HAVE_KRETPROBES 202 config HAVE_KRETPROBES
218 bool 203 bool
219 204
220 config HAVE_OPTPROBES 205 config HAVE_OPTPROBES
221 bool 206 bool
222 207
223 config HAVE_KPROBES_ON_FTRACE 208 config HAVE_KPROBES_ON_FTRACE
224 bool 209 bool
225 210
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 211 config HAVE_FUNCTION_ERROR_INJECTION
235 bool 212 bool
236 213
237 config HAVE_NMI 214 config HAVE_NMI
238 bool 215 bool
239 216
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 # 217 #
250 # An arch should select this if it provides al 218 # An arch should select this if it provides all these things:
251 # 219 #
252 # task_pt_regs() in asm/process 220 # task_pt_regs() in asm/processor.h or asm/ptrace.h
253 # arch_has_single_step() if there is ha 221 # arch_has_single_step() if there is hardware single-step support
254 # arch_has_block_step() if there is ha 222 # arch_has_block_step() if there is hardware block-step support
255 # asm/syscall.h supplying asm- 223 # asm/syscall.h supplying asm-generic/syscall.h interface
256 # linux/regset.h user_regset in 224 # linux/regset.h user_regset interfaces
257 # CORE_DUMP_USE_REGSET #define'd in l 225 # CORE_DUMP_USE_REGSET #define'd in linux/elf.h
258 # TIF_SYSCALL_TRACE calls ptrace_r !! 226 # TIF_SYSCALL_TRACE calls tracehook_report_syscall_{entry,exit}
259 # TIF_NOTIFY_RESUME calls resume_u !! 227 # TIF_NOTIFY_RESUME calls tracehook_notify_resume()
>> 228 # signal delivery calls tracehook_signal_handler()
260 # 229 #
261 config HAVE_ARCH_TRACEHOOK 230 config HAVE_ARCH_TRACEHOOK
262 bool 231 bool
263 232
264 config HAVE_DMA_CONTIGUOUS 233 config HAVE_DMA_CONTIGUOUS
265 bool 234 bool
266 235
267 config GENERIC_SMP_IDLE_THREAD 236 config GENERIC_SMP_IDLE_THREAD
268 bool !! 237 bool
269 238
270 config GENERIC_IDLE_POLL_SETUP 239 config GENERIC_IDLE_POLL_SETUP
271 bool !! 240 bool
272 241
273 config ARCH_HAS_FORTIFY_SOURCE 242 config ARCH_HAS_FORTIFY_SOURCE
274 bool 243 bool
275 help 244 help
276 An architecture should select this w 245 An architecture should select this when it can successfully
277 build and run with CONFIG_FORTIFY_SO 246 build and run with CONFIG_FORTIFY_SOURCE.
278 247
279 # <<
280 # Select if the arch provides a historic keepi <<
281 # command line option <<
282 # <<
283 config ARCH_HAS_KEEPINITRD <<
284 bool <<
285 <<
286 # Select if arch has all set_memory_ro/rw/x/nx 248 # Select if arch has all set_memory_ro/rw/x/nx() functions in asm/cacheflush.h
287 config ARCH_HAS_SET_MEMORY 249 config ARCH_HAS_SET_MEMORY
288 bool 250 bool
289 251
290 # Select if arch has all set_direct_map_invali !! 252 # Select if arch init_task must go in the __init_task_data section
291 config ARCH_HAS_SET_DIRECT_MAP !! 253 config ARCH_TASK_STRUCT_ON_STACK
292 bool !! 254 bool
293 255
294 # !! 256 # Select if arch has its private alloc_task_struct() function
295 # Select if the architecture provides the arch !! 257 config ARCH_TASK_STRUCT_ALLOCATOR
296 # either provide an uncached segment alias for <<
297 # to remap the page tables in place. <<
298 # <<
299 config ARCH_HAS_DMA_SET_UNCACHED <<
300 bool 258 bool
301 259
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 <<
308 <<
309 config ARCH_HAS_CPU_FINALIZE_INIT <<
310 bool <<
311 <<
312 # The architecture has a per-task state that i <<
313 config ARCH_HAS_CPU_PASID <<
314 bool <<
315 select IOMMU_MM_DATA <<
316 <<
317 config HAVE_ARCH_THREAD_STRUCT_WHITELIST 260 config HAVE_ARCH_THREAD_STRUCT_WHITELIST
318 bool 261 bool
>> 262 depends on !ARCH_TASK_STRUCT_ALLOCATOR
319 help 263 help
320 An architecture should select this t 264 An architecture should select this to provide hardened usercopy
321 knowledge about what region of the t 265 knowledge about what region of the thread_struct should be
322 whitelisted for copying to userspace 266 whitelisted for copying to userspace. Normally this is only the
323 FPU registers. Specifically, arch_th 267 FPU registers. Specifically, arch_thread_struct_whitelist()
324 should be implemented. Without this, 268 should be implemented. Without this, the entire thread_struct
325 field in task_struct will be left wh 269 field in task_struct will be left whitelisted.
326 270
327 # Select if arch wants to size task_struct dyn !! 271 # Select if arch has its private alloc_thread_stack() function
328 config ARCH_WANTS_DYNAMIC_TASK_STRUCT !! 272 config ARCH_THREAD_STACK_ALLOCATOR
329 bool 273 bool
330 274
331 config ARCH_WANTS_NO_INSTR !! 275 # Select if arch wants to size task_struct dynamically via arch_task_struct_size:
332 bool !! 276 config ARCH_WANTS_DYNAMIC_TASK_STRUCT
333 help <<
334 An architecture should select this i <<
335 functions to denote that the toolcha <<
336 functions and is required for correc <<
337 <<
338 config ARCH_32BIT_OFF_T <<
339 bool <<
340 depends on !64BIT <<
341 help <<
342 All new 32-bit architectures should <<
343 userspace side which corresponds to <<
344 is the requirement for modern ABIs. <<
345 still support 32-bit off_t. This opt <<
346 architectures explicitly. <<
347 <<
348 # Selected by 64 bit architectures which have <<
349 config ARCH_32BIT_USTAT_F_TINODE <<
350 bool <<
351 <<
352 config HAVE_ASM_MODVERSIONS <<
353 bool 277 bool
354 help <<
355 This symbol should be selected by an <<
356 <asm/asm-prototypes.h> to support th <<
357 exported from assembly code. <<
358 278
359 config HAVE_REGS_AND_STACK_ACCESS_API 279 config HAVE_REGS_AND_STACK_ACCESS_API
360 bool 280 bool
361 help 281 help
362 This symbol should be selected by an !! 282 This symbol should be selected by an architecure if it supports
363 the API needed to access registers a 283 the API needed to access registers and stack entries from pt_regs,
364 declared in asm/ptrace.h 284 declared in asm/ptrace.h
365 For example the kprobes-based event 285 For example the kprobes-based event tracer needs this API.
366 286
367 config HAVE_RSEQ 287 config HAVE_RSEQ
368 bool 288 bool
369 depends on HAVE_REGS_AND_STACK_ACCESS_ 289 depends on HAVE_REGS_AND_STACK_ACCESS_API
370 help 290 help
371 This symbol should be selected by an 291 This symbol should be selected by an architecture if it
372 supports an implementation of restar 292 supports an implementation of restartable sequences.
373 293
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 294 config HAVE_FUNCTION_ARG_ACCESS_API
381 bool 295 bool
382 help 296 help
383 This symbol should be selected by an !! 297 This symbol should be selected by an architecure if it supports
384 the API needed to access function ar 298 the API needed to access function arguments from pt_regs,
385 declared in asm/ptrace.h 299 declared in asm/ptrace.h
386 300
>> 301 config HAVE_CLK
>> 302 bool
>> 303 help
>> 304 The <linux/clk.h> calls support software clock gating and
>> 305 thus are a key power management tool on many systems.
>> 306
387 config HAVE_HW_BREAKPOINT 307 config HAVE_HW_BREAKPOINT
388 bool 308 bool
389 depends on PERF_EVENTS 309 depends on PERF_EVENTS
390 310
391 config HAVE_MIXED_BREAKPOINTS_REGS 311 config HAVE_MIXED_BREAKPOINTS_REGS
392 bool 312 bool
393 depends on HAVE_HW_BREAKPOINT 313 depends on HAVE_HW_BREAKPOINT
394 help 314 help
395 Depending on the arch implementation 315 Depending on the arch implementation of hardware breakpoints,
396 some of them have separate registers 316 some of them have separate registers for data and instruction
397 breakpoints addresses, others have m 317 breakpoints addresses, others have mixed registers to store
398 them but define the access type in a 318 them but define the access type in a control register.
399 Select this option if your arch impl 319 Select this option if your arch implements breakpoints under the
400 latter fashion. 320 latter fashion.
401 321
402 config HAVE_USER_RETURN_NOTIFIER 322 config HAVE_USER_RETURN_NOTIFIER
403 bool 323 bool
404 324
405 config HAVE_PERF_EVENTS_NMI 325 config HAVE_PERF_EVENTS_NMI
406 bool 326 bool
407 help 327 help
408 System hardware can generate an NMI 328 System hardware can generate an NMI using the perf event
409 subsystem. Also has support for cal 329 subsystem. Also has support for calculating CPU cycle events
410 to determine how many clock cycles i 330 to determine how many clock cycles in a given period.
411 331
412 config HAVE_HARDLOCKUP_DETECTOR_PERF 332 config HAVE_HARDLOCKUP_DETECTOR_PERF
413 bool 333 bool
414 depends on HAVE_PERF_EVENTS_NMI 334 depends on HAVE_PERF_EVENTS_NMI
415 help 335 help
416 The arch chooses to use the generic 336 The arch chooses to use the generic perf-NMI-based hardlockup
417 detector. Must define HAVE_PERF_EVEN 337 detector. Must define HAVE_PERF_EVENTS_NMI.
418 338
419 config HAVE_HARDLOCKUP_DETECTOR_ARCH !! 339 config HAVE_NMI_WATCHDOG
>> 340 depends on HAVE_NMI
420 bool 341 bool
421 help 342 help
422 The arch provides its own hardlockup !! 343 The arch provides a low level NMI watchdog. It provides
423 of the generic ones. !! 344 asm/nmi.h, and defines its own arch_touch_nmi_watchdog().
424 345
425 It uses the same command line parame !! 346 config HAVE_HARDLOCKUP_DETECTOR_ARCH
426 as the generic hardlockup detectors. !! 347 bool
>> 348 select HAVE_NMI_WATCHDOG
>> 349 help
>> 350 The arch chooses to provide its own hardlockup detector, which is
>> 351 a superset of the HAVE_NMI_WATCHDOG. It also conforms to config
>> 352 interfaces and parameters provided by hardlockup detector subsystem.
427 353
428 config HAVE_PERF_REGS 354 config HAVE_PERF_REGS
429 bool 355 bool
430 help 356 help
431 Support selective register dumps for 357 Support selective register dumps for perf events. This includes
432 bit-mapping of each registers and a 358 bit-mapping of each registers and a unique architecture id.
433 359
434 config HAVE_PERF_USER_STACK_DUMP 360 config HAVE_PERF_USER_STACK_DUMP
435 bool 361 bool
436 help 362 help
437 Support user stack dumps for perf ev 363 Support user stack dumps for perf event samples. This needs
438 access to the user stack pointer whi 364 access to the user stack pointer which is not unified across
439 architectures. 365 architectures.
440 366
441 config HAVE_ARCH_JUMP_LABEL 367 config HAVE_ARCH_JUMP_LABEL
442 bool 368 bool
443 369
444 config HAVE_ARCH_JUMP_LABEL_RELATIVE 370 config HAVE_ARCH_JUMP_LABEL_RELATIVE
445 bool 371 bool
446 372
447 config MMU_GATHER_TABLE_FREE !! 373 config HAVE_RCU_TABLE_FREE
448 bool <<
449 <<
450 config MMU_GATHER_RCU_TABLE_FREE <<
451 bool <<
452 select MMU_GATHER_TABLE_FREE <<
453 <<
454 config MMU_GATHER_PAGE_SIZE <<
455 bool 374 bool
456 375
457 config MMU_GATHER_NO_RANGE !! 376 config HAVE_RCU_TABLE_INVALIDATE
458 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 <<
467 config MMU_GATHER_NO_GATHER <<
468 bool <<
469 depends on MMU_GATHER_TABLE_FREE <<
470 <<
471 config ARCH_WANT_IRQS_OFF_ACTIVATE_MM <<
472 bool <<
473 help <<
474 Temporary select until all architect <<
475 irqs disabled over activate_mm. Arch <<
476 shootdowns should enable this. <<
477 <<
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 377 bool
509 378
510 config ARCH_HAVE_NMI_SAFE_CMPXCHG 379 config ARCH_HAVE_NMI_SAFE_CMPXCHG
511 bool 380 bool
512 381
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 382 config HAVE_ALIGNED_STRUCT_PAGE
526 bool 383 bool
527 help 384 help
528 This makes sure that struct pages ar 385 This makes sure that struct pages are double word aligned and that
529 e.g. the SLUB allocator can perform 386 e.g. the SLUB allocator can perform double word atomic operations
530 on a struct page for better performa 387 on a struct page for better performance. However selecting this
531 might increase the size of a struct 388 might increase the size of a struct page by a word.
532 389
533 config HAVE_CMPXCHG_LOCAL 390 config HAVE_CMPXCHG_LOCAL
534 bool 391 bool
535 392
536 config HAVE_CMPXCHG_DOUBLE 393 config HAVE_CMPXCHG_DOUBLE
537 bool 394 bool
538 395
539 config ARCH_WEAK_RELEASE_ACQUIRE 396 config ARCH_WEAK_RELEASE_ACQUIRE
540 bool 397 bool
541 398
542 config ARCH_WANT_IPC_PARSE_VERSION 399 config ARCH_WANT_IPC_PARSE_VERSION
543 bool 400 bool
544 401
545 config ARCH_WANT_COMPAT_IPC_PARSE_VERSION 402 config ARCH_WANT_COMPAT_IPC_PARSE_VERSION
546 bool 403 bool
547 404
548 config ARCH_WANT_OLD_COMPAT_IPC 405 config ARCH_WANT_OLD_COMPAT_IPC
549 select ARCH_WANT_COMPAT_IPC_PARSE_VERS 406 select ARCH_WANT_COMPAT_IPC_PARSE_VERSION
550 bool 407 bool
551 408
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 409 config HAVE_ARCH_SECCOMP_FILTER
564 bool 410 bool
565 select HAVE_ARCH_SECCOMP <<
566 help 411 help
567 An arch should select this symbol if 412 An arch should select this symbol if it provides all of these things:
568 - all the requirements for HAVE_ARCH <<
569 - syscall_get_arch() 413 - syscall_get_arch()
570 - syscall_get_arguments() 414 - syscall_get_arguments()
571 - syscall_rollback() 415 - syscall_rollback()
572 - syscall_set_return_value() 416 - syscall_set_return_value()
573 - SIGSYS siginfo_t support 417 - SIGSYS siginfo_t support
574 - secure_computing is called from a 418 - secure_computing is called from a ptrace_event()-safe context
575 - secure_computing return value is c 419 - secure_computing return value is checked and a return value of -1
576 results in the system call being s 420 results in the system call being skipped immediately.
577 - seccomp syscall wired up 421 - 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. <<
598 422
599 config SECCOMP_FILTER 423 config SECCOMP_FILTER
600 def_bool y 424 def_bool y
601 depends on HAVE_ARCH_SECCOMP_FILTER && 425 depends on HAVE_ARCH_SECCOMP_FILTER && SECCOMP && NET
602 help 426 help
603 Enable tasks to build secure computi 427 Enable tasks to build secure computing environments defined
604 in terms of Berkeley Packet Filter p 428 in terms of Berkeley Packet Filter programs which implement
605 task-defined system call filtering p 429 task-defined system call filtering polices.
606 430
607 See Documentation/userspace-api/secc 431 See Documentation/userspace-api/seccomp_filter.rst for details.
608 432
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 433 config HAVE_ARCH_STACKLEAK
624 bool 434 bool
625 help 435 help
626 An architecture should select this i 436 An architecture should select this if it has the code which
627 fills the used part of the kernel st 437 fills the used part of the kernel stack with the STACKLEAK_POISON
628 value before returning from system c 438 value before returning from system calls.
629 439
630 config HAVE_STACKPROTECTOR 440 config HAVE_STACKPROTECTOR
631 bool 441 bool
632 help 442 help
633 An arch should select this symbol if 443 An arch should select this symbol if:
634 - it has implemented a stack canary 444 - it has implemented a stack canary (e.g. __stack_chk_guard)
635 445
>> 446 config CC_HAS_STACKPROTECTOR_NONE
>> 447 def_bool $(cc-option,-fno-stack-protector)
>> 448
636 config STACKPROTECTOR 449 config STACKPROTECTOR
637 bool "Stack Protector buffer overflow 450 bool "Stack Protector buffer overflow detection"
638 depends on HAVE_STACKPROTECTOR 451 depends on HAVE_STACKPROTECTOR
639 depends on $(cc-option,-fstack-protect 452 depends on $(cc-option,-fstack-protector)
640 default y 453 default y
641 help 454 help
642 This option turns on the "stack-prot 455 This option turns on the "stack-protector" GCC feature. This
643 feature puts, at the beginning of fu 456 feature puts, at the beginning of functions, a canary value on
644 the stack just before the return add 457 the stack just before the return address, and validates
645 the value just before actually retur 458 the value just before actually returning. Stack based buffer
646 overflows (that need to overwrite th 459 overflows (that need to overwrite this return address) now also
647 overwrite the canary, which gets det 460 overwrite the canary, which gets detected and the attack is then
648 neutralized via a kernel panic. 461 neutralized via a kernel panic.
649 462
650 Functions will have the stack-protec 463 Functions will have the stack-protector canary logic added if they
651 have an 8-byte or larger character a 464 have an 8-byte or larger character array on the stack.
652 465
653 This feature requires gcc version 4. 466 This feature requires gcc version 4.2 or above, or a distribution
654 gcc with the feature backported ("-f 467 gcc with the feature backported ("-fstack-protector").
655 468
656 On an x86 "defconfig" build, this fe 469 On an x86 "defconfig" build, this feature adds canary checks to
657 about 3% of all kernel functions, wh 470 about 3% of all kernel functions, which increases kernel code size
658 by about 0.3%. 471 by about 0.3%.
659 472
660 config STACKPROTECTOR_STRONG 473 config STACKPROTECTOR_STRONG
661 bool "Strong Stack Protector" 474 bool "Strong Stack Protector"
662 depends on STACKPROTECTOR 475 depends on STACKPROTECTOR
663 depends on $(cc-option,-fstack-protect 476 depends on $(cc-option,-fstack-protector-strong)
664 default y 477 default y
665 help 478 help
666 Functions will have the stack-protec 479 Functions will have the stack-protector canary logic added in any
667 of the following conditions: 480 of the following conditions:
668 481
669 - local variable's address used as p 482 - local variable's address used as part of the right hand side of an
670 assignment or function argument 483 assignment or function argument
671 - local variable is an array (or uni 484 - local variable is an array (or union containing an array),
672 regardless of array type or length 485 regardless of array type or length
673 - uses register local variables 486 - uses register local variables
674 487
675 This feature requires gcc version 4. 488 This feature requires gcc version 4.9 or above, or a distribution
676 gcc with the feature backported ("-f 489 gcc with the feature backported ("-fstack-protector-strong").
677 490
678 On an x86 "defconfig" build, this fe 491 On an x86 "defconfig" build, this feature adds canary checks to
679 about 20% of all kernel functions, w 492 about 20% of all kernel functions, which increases the kernel code
680 size by about 2%. 493 size by about 2%.
681 494
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 495 config HAVE_ARCH_WITHIN_STACK_FRAMES
840 bool 496 bool
841 help 497 help
842 An architecture should select this i 498 An architecture should select this if it can walk the kernel stack
843 frames to determine if an object is 499 frames to determine if an object is part of either the arguments
844 or local variables (i.e. that it exc 500 or local variables (i.e. that it excludes saved return addresses,
845 and similar) by implementing an inli 501 and similar) by implementing an inline arch_within_stack_frames(),
846 which is used by CONFIG_HARDENED_USE 502 which is used by CONFIG_HARDENED_USERCOPY.
847 503
848 config HAVE_CONTEXT_TRACKING_USER !! 504 config HAVE_CONTEXT_TRACKING
849 bool 505 bool
850 help 506 help
851 Provide kernel/user boundaries probe 507 Provide kernel/user boundaries probes necessary for subsystems
852 that need it, such as userspace RCU 508 that need it, such as userspace RCU extended quiescent state.
853 Syscalls need to be wrapped inside u !! 509 Syscalls need to be wrapped inside user_exit()-user_enter() through
854 optimized behind static key or throu !! 510 the slow path using TIF_NOHZ flag. Exceptions handlers must be
855 flag. Exceptions handlers must be wr !! 511 wrapped as well. Irqs are already protected inside
856 protected inside ct_irq_enter/ct_irq !! 512 rcu_irq_enter/rcu_irq_exit() but preemption or signal handling on
857 handling on irq exit still need to b !! 513 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_ <<
881 514
882 config HAVE_VIRT_CPU_ACCOUNTING 515 config HAVE_VIRT_CPU_ACCOUNTING
883 bool 516 bool
884 517
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 518 config ARCH_HAS_SCALED_CPUTIME
892 bool 519 bool
893 520
894 config HAVE_VIRT_CPU_ACCOUNTING_GEN 521 config HAVE_VIRT_CPU_ACCOUNTING_GEN
895 bool 522 bool
896 default y if 64BIT 523 default y if 64BIT
897 help 524 help
898 With VIRT_CPU_ACCOUNTING_GEN, cputim 525 With VIRT_CPU_ACCOUNTING_GEN, cputime_t becomes 64-bit.
899 Before enabling this option, arch co 526 Before enabling this option, arch code must be audited
900 to ensure there are no races in conc 527 to ensure there are no races in concurrent read/write of
901 cputime_t. For example, reading/writ 528 cputime_t. For example, reading/writing 64-bit cputime_t on
902 some 32-bit arches may require multi 529 some 32-bit arches may require multiple accesses, so proper
903 locking is needed to protect against 530 locking is needed to protect against concurrent accesses.
904 531
>> 532
905 config HAVE_IRQ_TIME_ACCOUNTING 533 config HAVE_IRQ_TIME_ACCOUNTING
906 bool 534 bool
907 help 535 help
908 Archs need to ensure they use a high 536 Archs need to ensure they use a high enough resolution clock to
909 support irq time accounting and then 537 support irq time accounting and then call enable_sched_clock_irqtime().
910 538
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 539 config HAVE_MOVE_PMD
919 bool 540 bool
920 help 541 help
921 Archs that select this are able to m 542 Archs that select this are able to move page tables at the PMD level.
922 543
923 config HAVE_ARCH_TRANSPARENT_HUGEPAGE 544 config HAVE_ARCH_TRANSPARENT_HUGEPAGE
924 bool 545 bool
925 546
926 config HAVE_ARCH_TRANSPARENT_HUGEPAGE_PUD 547 config HAVE_ARCH_TRANSPARENT_HUGEPAGE_PUD
927 bool 548 bool
928 549
929 config HAVE_ARCH_HUGE_VMAP 550 config HAVE_ARCH_HUGE_VMAP
930 bool 551 bool
931 552
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 <<
942 bool <<
943 <<
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 553 config HAVE_ARCH_SOFT_DIRTY
953 bool 554 bool
954 555
955 config HAVE_MOD_ARCH_SPECIFIC 556 config HAVE_MOD_ARCH_SPECIFIC
956 bool 557 bool
957 help 558 help
958 The arch uses struct mod_arch_specif 559 The arch uses struct mod_arch_specific to store data. Many arches
959 just need a simple module loader wit 560 just need a simple module loader without arch specific data - those
960 should not enable this. 561 should not enable this.
961 562
962 config MODULES_USE_ELF_RELA 563 config MODULES_USE_ELF_RELA
963 bool 564 bool
964 help 565 help
965 Modules only use ELF RELA relocation 566 Modules only use ELF RELA relocations. Modules with ELF REL
966 relocations will give an error. 567 relocations will give an error.
967 568
968 config MODULES_USE_ELF_REL 569 config MODULES_USE_ELF_REL
969 bool 570 bool
970 help 571 help
971 Modules only use ELF REL relocations 572 Modules only use ELF REL relocations. Modules with ELF RELA
972 relocations will give an error. 573 relocations will give an error.
973 574
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 575 config HAVE_IRQ_EXIT_ON_IRQ_STACK
989 bool 576 bool
990 help 577 help
991 Architecture doesn't only execute th 578 Architecture doesn't only execute the irq handler on the irq stack
992 but also irq_exit(). This way we can 579 but also irq_exit(). This way we can process softirqs on this irq
993 stack instead of switching to a new 580 stack instead of switching to a new one when we call __do_softirq()
994 in the end of an hardirq. 581 in the end of an hardirq.
995 This spares a stack switch and impro 582 This spares a stack switch and improves cache usage on softirq
996 processing. 583 processing.
997 584
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 585 config PGTABLE_LEVELS
1015 int 586 int
1016 default 2 587 default 2
1017 588
1018 config ARCH_HAS_ELF_RANDOMIZE 589 config ARCH_HAS_ELF_RANDOMIZE
1019 bool 590 bool
1020 help 591 help
1021 An architecture supports choosing r 592 An architecture supports choosing randomized locations for
1022 stack, mmap, brk, and ET_DYN. Defin 593 stack, mmap, brk, and ET_DYN. Defined functions:
1023 - arch_mmap_rnd() 594 - arch_mmap_rnd()
1024 - arch_randomize_brk() 595 - arch_randomize_brk()
1025 596
1026 config HAVE_ARCH_MMAP_RND_BITS 597 config HAVE_ARCH_MMAP_RND_BITS
1027 bool 598 bool
1028 help 599 help
1029 An arch should select this symbol i 600 An arch should select this symbol if it supports setting a variable
1030 number of bits for use in establish 601 number of bits for use in establishing the base address for mmap
1031 allocations, has MMU enabled and pr 602 allocations, has MMU enabled and provides values for both:
1032 - ARCH_MMAP_RND_BITS_MIN 603 - ARCH_MMAP_RND_BITS_MIN
1033 - ARCH_MMAP_RND_BITS_MAX 604 - ARCH_MMAP_RND_BITS_MAX
1034 605
1035 config HAVE_EXIT_THREAD 606 config HAVE_EXIT_THREAD
1036 bool 607 bool
1037 help 608 help
1038 An architecture implements exit_thr 609 An architecture implements exit_thread.
1039 610
1040 config ARCH_MMAP_RND_BITS_MIN 611 config ARCH_MMAP_RND_BITS_MIN
1041 int 612 int
1042 613
1043 config ARCH_MMAP_RND_BITS_MAX 614 config ARCH_MMAP_RND_BITS_MAX
1044 int 615 int
1045 616
1046 config ARCH_MMAP_RND_BITS_DEFAULT 617 config ARCH_MMAP_RND_BITS_DEFAULT
1047 int 618 int
1048 619
1049 config ARCH_MMAP_RND_BITS 620 config ARCH_MMAP_RND_BITS
1050 int "Number of bits to use for ASLR o 621 int "Number of bits to use for ASLR of mmap base address" if EXPERT
1051 range ARCH_MMAP_RND_BITS_MIN ARCH_MMA 622 range ARCH_MMAP_RND_BITS_MIN ARCH_MMAP_RND_BITS_MAX
1052 default ARCH_MMAP_RND_BITS_DEFAULT if 623 default ARCH_MMAP_RND_BITS_DEFAULT if ARCH_MMAP_RND_BITS_DEFAULT
1053 default ARCH_MMAP_RND_BITS_MIN 624 default ARCH_MMAP_RND_BITS_MIN
1054 depends on HAVE_ARCH_MMAP_RND_BITS 625 depends on HAVE_ARCH_MMAP_RND_BITS
1055 help 626 help
1056 This value can be used to select th 627 This value can be used to select the number of bits to use to
1057 determine the random offset to the 628 determine the random offset to the base address of vma regions
1058 resulting from mmap allocations. Th 629 resulting from mmap allocations. This value will be bounded
1059 by the architecture's minimum and m 630 by the architecture's minimum and maximum supported values.
1060 631
1061 This value can be changed after boo 632 This value can be changed after boot using the
1062 /proc/sys/vm/mmap_rnd_bits tunable 633 /proc/sys/vm/mmap_rnd_bits tunable
1063 634
1064 config HAVE_ARCH_MMAP_RND_COMPAT_BITS 635 config HAVE_ARCH_MMAP_RND_COMPAT_BITS
1065 bool 636 bool
1066 help 637 help
1067 An arch should select this symbol i 638 An arch should select this symbol if it supports running applications
1068 in compatibility mode, supports set 639 in compatibility mode, supports setting a variable number of bits for
1069 use in establishing the base addres 640 use in establishing the base address for mmap allocations, has MMU
1070 enabled and provides values for bot 641 enabled and provides values for both:
1071 - ARCH_MMAP_RND_COMPAT_BITS_MIN 642 - ARCH_MMAP_RND_COMPAT_BITS_MIN
1072 - ARCH_MMAP_RND_COMPAT_BITS_MAX 643 - ARCH_MMAP_RND_COMPAT_BITS_MAX
1073 644
1074 config ARCH_MMAP_RND_COMPAT_BITS_MIN 645 config ARCH_MMAP_RND_COMPAT_BITS_MIN
1075 int 646 int
1076 647
1077 config ARCH_MMAP_RND_COMPAT_BITS_MAX 648 config ARCH_MMAP_RND_COMPAT_BITS_MAX
1078 int 649 int
1079 650
1080 config ARCH_MMAP_RND_COMPAT_BITS_DEFAULT 651 config ARCH_MMAP_RND_COMPAT_BITS_DEFAULT
1081 int 652 int
1082 653
1083 config ARCH_MMAP_RND_COMPAT_BITS 654 config ARCH_MMAP_RND_COMPAT_BITS
1084 int "Number of bits to use for ASLR o 655 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 656 range ARCH_MMAP_RND_COMPAT_BITS_MIN ARCH_MMAP_RND_COMPAT_BITS_MAX
1086 default ARCH_MMAP_RND_COMPAT_BITS_DEF 657 default ARCH_MMAP_RND_COMPAT_BITS_DEFAULT if ARCH_MMAP_RND_COMPAT_BITS_DEFAULT
1087 default ARCH_MMAP_RND_COMPAT_BITS_MIN 658 default ARCH_MMAP_RND_COMPAT_BITS_MIN
1088 depends on HAVE_ARCH_MMAP_RND_COMPAT_ 659 depends on HAVE_ARCH_MMAP_RND_COMPAT_BITS
1089 help 660 help
1090 This value can be used to select th 661 This value can be used to select the number of bits to use to
1091 determine the random offset to the 662 determine the random offset to the base address of vma regions
1092 resulting from mmap allocations for 663 resulting from mmap allocations for compatible applications This
1093 value will be bounded by the archit 664 value will be bounded by the architecture's minimum and maximum
1094 supported values. 665 supported values.
1095 666
1096 This value can be changed after boo 667 This value can be changed after boot using the
1097 /proc/sys/vm/mmap_rnd_compat_bits t 668 /proc/sys/vm/mmap_rnd_compat_bits tunable
1098 669
1099 config HAVE_ARCH_COMPAT_MMAP_BASES 670 config HAVE_ARCH_COMPAT_MMAP_BASES
1100 bool 671 bool
1101 help 672 help
1102 This allows 64bit applications to i 673 This allows 64bit applications to invoke 32-bit mmap() syscall
1103 and vice-versa 32-bit applications 674 and vice-versa 32-bit applications to call 64-bit mmap().
1104 Required for applications doing dif 675 Required for applications doing different bitness syscalls.
1105 676
1106 config HAVE_PAGE_SIZE_4KB !! 677 config HAVE_COPY_THREAD_TLS
1107 bool <<
1108 <<
1109 config HAVE_PAGE_SIZE_8KB <<
1110 bool <<
1111 <<
1112 config HAVE_PAGE_SIZE_16KB <<
1113 bool 678 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 679 help
1142 This option is the only supported p !! 680 Architecture provides copy_thread_tls to accept tls argument via
1143 processors, and can be slightly fas !! 681 normal C parameter passing, rather than extracting the syscall
1144 !! 682 argument from pt_regs.
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 <<
1208 # address by giving priority to top-down sche <<
1209 # is not in legacy mode (compat task, unlimit <<
1210 # sysctl_legacy_va_layout). <<
1211 # Architecture that selects this option can p <<
1212 # - STACK_RND_MASK <<
1213 config ARCH_WANT_DEFAULT_TOPDOWN_MMAP_LAYOUT <<
1214 bool <<
1215 depends on MMU <<
1216 select ARCH_HAS_ELF_RANDOMIZE <<
1217 <<
1218 config HAVE_OBJTOOL <<
1219 bool <<
1220 <<
1221 config HAVE_JUMP_LABEL_HACK <<
1222 bool <<
1223 <<
1224 config HAVE_NOINSTR_HACK <<
1225 bool <<
1226 <<
1227 config HAVE_NOINSTR_VALIDATION <<
1228 bool <<
1229 <<
1230 config HAVE_UACCESS_VALIDATION <<
1231 bool <<
1232 select OBJTOOL <<
1233 683
1234 config HAVE_STACK_VALIDATION 684 config HAVE_STACK_VALIDATION
1235 bool 685 bool
1236 help 686 help
1237 Architecture supports objtool compi !! 687 Architecture supports the 'objtool check' host tool command, which
1238 validation. !! 688 performs compile-time stack metadata validation.
1239 689
1240 config HAVE_RELIABLE_STACKTRACE 690 config HAVE_RELIABLE_STACKTRACE
1241 bool 691 bool
1242 help 692 help
1243 Architecture has either save_stack_ !! 693 Architecture has a save_stack_trace_tsk_reliable() function which
1244 arch_stack_walk_reliable() function !! 694 only returns a stack trace if it can guarantee the trace is reliable.
1245 if it can guarantee the trace is re <<
1246 695
1247 config HAVE_ARCH_HASH 696 config HAVE_ARCH_HASH
1248 bool 697 bool
1249 default n 698 default n
1250 help 699 help
1251 If this is set, the architecture pr 700 If this is set, the architecture provides an <asm/hash.h>
1252 file which provides platform-specif 701 file which provides platform-specific implementations of some
1253 functions in <linux/hash.h> or fs/n 702 functions in <linux/hash.h> or fs/namei.c.
1254 703
1255 config HAVE_ARCH_NVRAM_OPS <<
1256 bool <<
1257 <<
1258 config ISA_BUS_API 704 config ISA_BUS_API
1259 def_bool ISA 705 def_bool ISA
1260 706
1261 # 707 #
1262 # ABI hall of shame 708 # ABI hall of shame
1263 # 709 #
1264 config CLONE_BACKWARDS 710 config CLONE_BACKWARDS
1265 bool 711 bool
1266 help 712 help
1267 Architecture has tls passed as the 713 Architecture has tls passed as the 4th argument of clone(2),
1268 not the 5th one. 714 not the 5th one.
1269 715
1270 config CLONE_BACKWARDS2 716 config CLONE_BACKWARDS2
1271 bool 717 bool
1272 help 718 help
1273 Architecture has the first two argu 719 Architecture has the first two arguments of clone(2) swapped.
1274 720
1275 config CLONE_BACKWARDS3 721 config CLONE_BACKWARDS3
1276 bool 722 bool
1277 help 723 help
1278 Architecture has tls passed as the 724 Architecture has tls passed as the 3rd argument of clone(2),
1279 not the 5th one. 725 not the 5th one.
1280 726
1281 config ODD_RT_SIGACTION 727 config ODD_RT_SIGACTION
1282 bool 728 bool
1283 help 729 help
1284 Architecture has unusual rt_sigacti 730 Architecture has unusual rt_sigaction(2) arguments
1285 731
1286 config OLD_SIGSUSPEND 732 config OLD_SIGSUSPEND
1287 bool 733 bool
1288 help 734 help
1289 Architecture has old sigsuspend(2) 735 Architecture has old sigsuspend(2) syscall, of one-argument variety
1290 736
1291 config OLD_SIGSUSPEND3 737 config OLD_SIGSUSPEND3
1292 bool 738 bool
1293 help 739 help
1294 Even weirder antique ABI - three-ar 740 Even weirder antique ABI - three-argument sigsuspend(2)
1295 741
1296 config OLD_SIGACTION 742 config OLD_SIGACTION
1297 bool 743 bool
1298 help 744 help
1299 Architecture has old sigaction(2) s 745 Architecture has old sigaction(2) syscall. Nope, not the same
1300 as OLD_SIGSUSPEND | OLD_SIGSUSPEND3 746 as OLD_SIGSUSPEND | OLD_SIGSUSPEND3 - alpha has sigsuspend(2),
1301 but fairly different variant of sig 747 but fairly different variant of sigaction(2), thanks to OSF/1
1302 compatibility... 748 compatibility...
1303 749
1304 config COMPAT_OLD_SIGACTION 750 config COMPAT_OLD_SIGACTION
1305 bool 751 bool
1306 752
>> 753 config 64BIT_TIME
>> 754 def_bool ARCH_HAS_64BIT_TIME
>> 755 help
>> 756 This should be selected by all architectures that need to support
>> 757 new system calls with a 64-bit time_t. This is relevant on all 32-bit
>> 758 architectures, and 64-bit architectures as part of compat syscall
>> 759 handling.
>> 760
1307 config COMPAT_32BIT_TIME 761 config COMPAT_32BIT_TIME
1308 bool "Provide system calls for 32-bit !! 762 def_bool (!64BIT && 64BIT_TIME) || COMPAT
1309 default !64BIT || COMPAT <<
1310 help 763 help
1311 This enables 32 bit time_t support 764 This enables 32 bit time_t support in addition to 64 bit time_t support.
1312 This is relevant on all 32-bit arch 765 This is relevant on all 32-bit architectures, and 64-bit architectures
1313 as part of compat syscall handling. 766 as part of compat syscall handling.
1314 767
1315 config ARCH_NO_PREEMPT !! 768 config ARCH_NO_COHERENT_DMA_MMAP
1316 bool 769 bool
1317 770
1318 config ARCH_SUPPORTS_RT !! 771 config ARCH_NO_PREEMPT
1319 bool 772 bool
1320 773
1321 config CPU_NO_EFFICIENT_FFS 774 config CPU_NO_EFFICIENT_FFS
1322 def_bool n 775 def_bool n
1323 776
1324 config HAVE_ARCH_VMAP_STACK 777 config HAVE_ARCH_VMAP_STACK
1325 def_bool n 778 def_bool n
1326 help 779 help
1327 An arch should select this symbol i 780 An arch should select this symbol if it can support kernel stacks
1328 in vmalloc space. This means: 781 in vmalloc space. This means:
1329 782
1330 - vmalloc space must be large enoug 783 - vmalloc space must be large enough to hold many kernel stacks.
1331 This may rule out many 32-bit arc 784 This may rule out many 32-bit architectures.
1332 785
1333 - Stacks in vmalloc space need to w 786 - Stacks in vmalloc space need to work reliably. For example, if
1334 vmap page tables are created on d 787 vmap page tables are created on demand, either this mechanism
1335 needs to work while the stack poi 788 needs to work while the stack points to a virtual address with
1336 unpopulated page tables or arch c 789 unpopulated page tables or arch code (switch_to() and switch_mm(),
1337 most likely) needs to ensure that 790 most likely) needs to ensure that the stack's page table entries
1338 are populated before running on a 791 are populated before running on a possibly unpopulated stack.
1339 792
1340 - If the stack overflows into a gua 793 - If the stack overflows into a guard page, something reasonable
1341 should happen. The definition of 794 should happen. The definition of "reasonable" is flexible, but
1342 instantly rebooting without loggi 795 instantly rebooting without logging anything would be unfriendly.
1343 796
1344 config VMAP_STACK 797 config VMAP_STACK
1345 default y 798 default y
1346 bool "Use a virtually-mapped stack" 799 bool "Use a virtually-mapped stack"
1347 depends on HAVE_ARCH_VMAP_STACK !! 800 depends on HAVE_ARCH_VMAP_STACK && !KASAN
1348 depends on !KASAN || KASAN_HW_TAGS || !! 801 ---help---
1349 help <<
1350 Enable this if you want the use vir 802 Enable this if you want the use virtually-mapped kernel stacks
1351 with guard pages. This causes kern 803 with guard pages. This causes kernel stack overflows to be
1352 caught immediately rather than caus 804 caught immediately rather than causing difficult-to-diagnose
1353 corruption. 805 corruption.
1354 806
1355 To use this with software KASAN mod !! 807 This is presently incompatible with KASAN because KASAN expects
1356 backing virtual mappings with real !! 808 the stack to map directly to the KASAN shadow map using a formula
1357 must be enabled. !! 809 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 810
1396 config ARCH_OPTIONAL_KERNEL_RWX 811 config ARCH_OPTIONAL_KERNEL_RWX
1397 def_bool n 812 def_bool n
1398 813
1399 config ARCH_OPTIONAL_KERNEL_RWX_DEFAULT 814 config ARCH_OPTIONAL_KERNEL_RWX_DEFAULT
1400 def_bool n 815 def_bool n
1401 816
1402 config ARCH_HAS_STRICT_KERNEL_RWX 817 config ARCH_HAS_STRICT_KERNEL_RWX
1403 def_bool n 818 def_bool n
1404 819
1405 config STRICT_KERNEL_RWX 820 config STRICT_KERNEL_RWX
1406 bool "Make kernel text and rodata rea 821 bool "Make kernel text and rodata read-only" if ARCH_OPTIONAL_KERNEL_RWX
1407 depends on ARCH_HAS_STRICT_KERNEL_RWX 822 depends on ARCH_HAS_STRICT_KERNEL_RWX
1408 default !ARCH_OPTIONAL_KERNEL_RWX || 823 default !ARCH_OPTIONAL_KERNEL_RWX || ARCH_OPTIONAL_KERNEL_RWX_DEFAULT
1409 help 824 help
1410 If this is set, kernel text and rod 825 If this is set, kernel text and rodata memory will be made read-only,
1411 and non-text memory will be made no 826 and non-text memory will be made non-executable. This provides
1412 protection against certain security 827 protection against certain security exploits (e.g. executing the heap
1413 or modifying text) 828 or modifying text)
1414 829
1415 These features are considered stand 830 These features are considered standard security practice these days.
1416 You should say Y here in almost all 831 You should say Y here in almost all cases.
1417 832
1418 config ARCH_HAS_STRICT_MODULE_RWX 833 config ARCH_HAS_STRICT_MODULE_RWX
1419 def_bool n 834 def_bool n
1420 835
1421 config STRICT_MODULE_RWX 836 config STRICT_MODULE_RWX
1422 bool "Set loadable kernel module data 837 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 838 depends on ARCH_HAS_STRICT_MODULE_RWX && MODULES
1424 default !ARCH_OPTIONAL_KERNEL_RWX || 839 default !ARCH_OPTIONAL_KERNEL_RWX || ARCH_OPTIONAL_KERNEL_RWX_DEFAULT
1425 help 840 help
1426 If this is set, module text and rod 841 If this is set, module text and rodata memory will be made read-only,
1427 and non-text memory will be made no 842 and non-text memory will be made non-executable. This provides
1428 protection against certain security 843 protection against certain security exploits (e.g. writing to text)
1429 844
1430 # select if the architecture provides an asm/ 845 # select if the architecture provides an asm/dma-direct.h header
1431 config ARCH_HAS_PHYS_TO_DMA 846 config ARCH_HAS_PHYS_TO_DMA
1432 bool 847 bool
1433 848
>> 849 config ARCH_HAS_REFCOUNT
>> 850 bool
>> 851 help
>> 852 An architecture selects this when it has implemented refcount_t
>> 853 using open coded assembly primitives that provide an optimized
>> 854 refcount_t implementation, possibly at the expense of some full
>> 855 refcount state checks of CONFIG_REFCOUNT_FULL=y.
>> 856
>> 857 The refcount overflow check behavior, however, must be retained.
>> 858 Catching overflows is the primary security concern for protecting
>> 859 against bugs in reference counts.
>> 860
>> 861 config REFCOUNT_FULL
>> 862 bool "Perform full reference count validation at the expense of speed"
>> 863 help
>> 864 Enabling this switches the refcounting infrastructure from a fast
>> 865 unchecked atomic_t implementation to a fully state checked
>> 866 implementation, which can be (slightly) slower but provides protections
>> 867 against various use-after-free conditions that can be used in
>> 868 security flaw exploits.
>> 869
1434 config HAVE_ARCH_COMPILER_H 870 config HAVE_ARCH_COMPILER_H
1435 bool 871 bool
1436 help 872 help
1437 An architecture can select this if 873 An architecture can select this if it provides an
1438 asm/compiler.h header that should b 874 asm/compiler.h header that should be included after
1439 linux/compiler-*.h in order to over 875 linux/compiler-*.h in order to override macro definitions that those
1440 headers generally provide. 876 headers generally provide.
1441 877
1442 config HAVE_ARCH_PREL32_RELOCATIONS 878 config HAVE_ARCH_PREL32_RELOCATIONS
1443 bool 879 bool
1444 help 880 help
1445 May be selected by an architecture 881 May be selected by an architecture if it supports place-relative
1446 32-bit relocations, both in the too 882 32-bit relocations, both in the toolchain and in the module loader,
1447 in which case relative references c 883 in which case relative references can be used in special sections
1448 for PCI fixup, initcalls etc which 884 for PCI fixup, initcalls etc which are only half the size on 64 bit
1449 architectures, and don't require ru 885 architectures, and don't require runtime relocation on relocatable
1450 kernels. 886 kernels.
1451 887
1452 config ARCH_USE_MEMREMAP_PROT <<
1453 bool <<
1454 <<
1455 config LOCK_EVENT_COUNTS <<
1456 bool "Locking event counts collection <<
1457 depends on DEBUG_FS <<
1458 help <<
1459 Enable light-weight counting of var <<
1460 in the system with minimal performa <<
1461 the chance of application behavior <<
1462 differences. The counts are reporte <<
1463 <<
1464 # Select if the architecture has support for <<
1465 config ARCH_HAS_RELR <<
1466 bool <<
1467 <<
1468 config RELR <<
1469 bool "Use RELR relocation packing" <<
1470 depends on ARCH_HAS_RELR && TOOLS_SUP <<
1471 default y <<
1472 help <<
1473 Store the kernel's dynamic relocati <<
1474 format. Requires a compatible linke <<
1475 well as compatible NM and OBJCOPY u <<
1476 are compatible). <<
1477 <<
1478 config ARCH_HAS_MEM_ENCRYPT <<
1479 bool <<
1480 <<
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" 888 source "kernel/gcov/Kconfig"
1604 889
1605 source "scripts/gcc-plugins/Kconfig" 890 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 891
1646 endmenu 892 endmenu
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