cpu/hotplug: Reset task stack state in _cpu_up()
[linux-block.git] / arch / Kconfig
CommitLineData
b2441318 1# SPDX-License-Identifier: GPL-2.0
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MD
2#
3# General architecture dependent options
4#
125e5645 5
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6#
7# Note: arch/$(SRCARCH)/Kconfig needs to be included first so that it can
8# override the default values in this file.
9#
10source "arch/$(SRCARCH)/Kconfig"
11
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RD
12menu "General architecture-dependent options"
13
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14config CRASH_CORE
15 bool
16
2965faa5 17config KEXEC_CORE
692f66f2 18 select CRASH_CORE
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DY
19 bool
20
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SS
21config KEXEC_ELF
22 bool
23
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TJB
24config HAVE_IMA_KEXEC
25 bool
26
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CM
27config ARCH_HAS_SUBPAGE_FAULTS
28 bool
29 help
30 Select if the architecture can check permissions at sub-page
31 granularity (e.g. arm64 MTE). The probe_user_*() functions
32 must be implemented.
33
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TG
34config HOTPLUG_SMT
35 bool
36
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37# Selected by HOTPLUG_CORE_SYNC_DEAD or HOTPLUG_CORE_SYNC_FULL
38config HOTPLUG_CORE_SYNC
39 bool
40
41# Basic CPU dead synchronization selected by architecture
42config HOTPLUG_CORE_SYNC_DEAD
43 bool
44 select HOTPLUG_CORE_SYNC
45
46# Full CPU synchronization with alive state selected by architecture
47config HOTPLUG_CORE_SYNC_FULL
48 bool
49 select HOTPLUG_CORE_SYNC_DEAD if HOTPLUG_CPU
50 select HOTPLUG_CORE_SYNC
51
142781e1 52config GENERIC_ENTRY
9f79ffc1 53 bool
142781e1 54
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MD
55config KPROBES
56 bool "Kprobes"
05ed160e 57 depends on MODULES
125e5645 58 depends on HAVE_KPROBES
05ed160e 59 select KALLSYMS
835f14ed 60 select TASKS_RCU if PREEMPTION
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MD
61 help
62 Kprobes allows you to trap at almost any kernel address and
63 execute a callback function. register_kprobe() establishes
64 a probepoint and specifies the callback. Kprobes is useful
65 for kernel debugging, non-intrusive instrumentation and testing.
66 If in doubt, say "N".
67
45f81b1c 68config JUMP_LABEL
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69 bool "Optimize very unlikely/likely branches"
70 depends on HAVE_ARCH_JUMP_LABEL
4ab7674f 71 select OBJTOOL if HAVE_JUMP_LABEL_HACK
24b54fee 72 help
9f79ffc1
JH
73 This option enables a transparent branch optimization that
74 makes certain almost-always-true or almost-always-false branch
75 conditions even cheaper to execute within the kernel.
c5905afb 76
9f79ffc1
JH
77 Certain performance-sensitive kernel code, such as trace points,
78 scheduler functionality, networking code and KVM have such
79 branches and include support for this optimization technique.
c5905afb 80
9f79ffc1
JH
81 If it is detected that the compiler has support for "asm goto",
82 the kernel will compile such branches with just a nop
83 instruction. When the condition flag is toggled to true, the
84 nop will be converted to a jump instruction to execute the
85 conditional block of instructions.
c5905afb 86
9f79ffc1
JH
87 This technique lowers overhead and stress on the branch prediction
88 of the processor and generally makes the kernel faster. The update
89 of the condition is slower, but those are always very rare.
45f81b1c 90
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JH
91 ( On 32-bit x86, the necessary options added to the compiler
92 flags may increase the size of the kernel slightly. )
45f81b1c 93
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PZ
94config STATIC_KEYS_SELFTEST
95 bool "Static key selftest"
96 depends on JUMP_LABEL
97 help
98 Boot time self-test of the branch patching code.
99
f03c4129
PZ
100config STATIC_CALL_SELFTEST
101 bool "Static call selftest"
102 depends on HAVE_STATIC_CALL
103 help
104 Boot time self-test of the call patching code.
105
afd66255 106config OPTPROBES
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MH
107 def_bool y
108 depends on KPROBES && HAVE_OPTPROBES
01b1d88b 109 select TASKS_RCU if PREEMPTION
afd66255 110
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MH
111config KPROBES_ON_FTRACE
112 def_bool y
113 depends on KPROBES && HAVE_KPROBES_ON_FTRACE
114 depends on DYNAMIC_FTRACE_WITH_REGS
115 help
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JH
116 If function tracer is enabled and the arch supports full
117 passing of pt_regs to function tracing, then kprobes can
118 optimize on top of function tracing.
e7dbfe34 119
2b144498 120config UPROBES
09294e31 121 def_bool n
e8f4aa60 122 depends on ARCH_SUPPORTS_UPROBES
2b144498 123 help
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IM
124 Uprobes is the user-space counterpart to kprobes: they
125 enable instrumentation applications (such as 'perf probe')
126 to establish unintrusive probes in user-space binaries and
127 libraries, by executing handler functions when the probes
128 are hit by user-space applications.
129
130 ( These probes come in the form of single-byte breakpoints,
131 managed by the kernel and kept transparent to the probed
132 application. )
2b144498 133
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SRV
134config HAVE_64BIT_ALIGNED_ACCESS
135 def_bool 64BIT && !HAVE_EFFICIENT_UNALIGNED_ACCESS
136 help
137 Some architectures require 64 bit accesses to be 64 bit
138 aligned, which also requires structs containing 64 bit values
139 to be 64 bit aligned too. This includes some 32 bit
140 architectures which can do 64 bit accesses, as well as 64 bit
141 architectures without unaligned access.
142
143 This symbol should be selected by an architecture if 64 bit
144 accesses are required to be 64 bit aligned in this way even
145 though it is not a 64 bit architecture.
146
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147 See Documentation/core-api/unaligned-memory-access.rst for
148 more information on the topic of unaligned memory accesses.
adab66b7 149
58340a07 150config HAVE_EFFICIENT_UNALIGNED_ACCESS
9ba16087 151 bool
58340a07
JB
152 help
153 Some architectures are unable to perform unaligned accesses
154 without the use of get_unaligned/put_unaligned. Others are
155 unable to perform such accesses efficiently (e.g. trap on
156 unaligned access and require fixing it up in the exception
157 handler.)
158
159 This symbol should be selected by an architecture if it can
160 perform unaligned accesses efficiently to allow different
161 code paths to be selected for these cases. Some network
162 drivers, for example, could opt to not fix up alignment
163 problems with received packets if doing so would not help
164 much.
165
c9b54d6f 166 See Documentation/core-api/unaligned-memory-access.rst for more
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JB
167 information on the topic of unaligned memory accesses.
168
cf66bb93 169config ARCH_USE_BUILTIN_BSWAP
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170 bool
171 help
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JH
172 Modern versions of GCC (since 4.4) have builtin functions
173 for handling byte-swapping. Using these, instead of the old
174 inline assembler that the architecture code provides in the
175 __arch_bswapXX() macros, allows the compiler to see what's
176 happening and offers more opportunity for optimisation. In
177 particular, the compiler will be able to combine the byteswap
178 with a nearby load or store and use load-and-swap or
179 store-and-swap instructions if the architecture has them. It
180 should almost *never* result in code which is worse than the
181 hand-coded assembler in <asm/swab.h>. But just in case it
182 does, the use of the builtins is optional.
cf66bb93 183
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JH
184 Any architecture with load-and-swap or store-and-swap
185 instructions should set this. And it shouldn't hurt to set it
186 on architectures that don't have such instructions.
cf66bb93 187
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188config KRETPROBES
189 def_bool y
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MH
190 depends on KPROBES && (HAVE_KRETPROBES || HAVE_RETHOOK)
191
192config KRETPROBE_ON_RETHOOK
193 def_bool y
194 depends on HAVE_RETHOOK
195 depends on KRETPROBES
196 select RETHOOK
9edddaa2 197
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198config USER_RETURN_NOTIFIER
199 bool
200 depends on HAVE_USER_RETURN_NOTIFIER
201 help
202 Provide a kernel-internal notification when a cpu is about to
203 switch to user mode.
204
28b2ee20 205config HAVE_IOREMAP_PROT
9ba16087 206 bool
28b2ee20 207
125e5645 208config HAVE_KPROBES
9ba16087 209 bool
9edddaa2
AM
210
211config HAVE_KRETPROBES
9ba16087 212 bool
74bc7cee 213
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MH
214config HAVE_OPTPROBES
215 bool
d314d74c 216
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MH
217config HAVE_KPROBES_ON_FTRACE
218 bool
219
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MH
220config ARCH_CORRECT_STACKTRACE_ON_KRETPROBE
221 bool
222 help
223 Since kretprobes modifies return address on the stack, the
224 stacktrace may see the kretprobe trampoline address instead
225 of correct one. If the architecture stacktrace code and
226 unwinder can adjust such entries, select this configuration.
227
540adea3 228config HAVE_FUNCTION_ERROR_INJECTION
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JB
229 bool
230
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231config HAVE_NMI
232 bool
233
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CL
234config HAVE_FUNCTION_DESCRIPTORS
235 bool
236
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MY
237config TRACE_IRQFLAGS_SUPPORT
238 bool
239
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240config TRACE_IRQFLAGS_NMI_SUPPORT
241 bool
242
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243#
244# An arch should select this if it provides all these things:
245#
246# task_pt_regs() in asm/processor.h or asm/ptrace.h
247# arch_has_single_step() if there is hardware single-step support
248# arch_has_block_step() if there is hardware block-step support
1f5a4ad9
RM
249# asm/syscall.h supplying asm-generic/syscall.h interface
250# linux/regset.h user_regset interfaces
251# CORE_DUMP_USE_REGSET #define'd in linux/elf.h
153474ba 252# TIF_SYSCALL_TRACE calls ptrace_report_syscall_{entry,exit}
03248add 253# TIF_NOTIFY_RESUME calls resume_user_mode_work()
1f5a4ad9
RM
254#
255config HAVE_ARCH_TRACEHOOK
9ba16087 256 bool
1f5a4ad9 257
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MS
258config HAVE_DMA_CONTIGUOUS
259 bool
260
29d5e047 261config GENERIC_SMP_IDLE_THREAD
24b54fee 262 bool
29d5e047 263
485cf5da 264config GENERIC_IDLE_POLL_SETUP
24b54fee 265 bool
485cf5da 266
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267config ARCH_HAS_FORTIFY_SOURCE
268 bool
269 help
270 An architecture should select this when it can successfully
271 build and run with CONFIG_FORTIFY_SOURCE.
272
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CH
273#
274# Select if the arch provides a historic keepinit alias for the retain_initrd
275# command line option
276#
277config ARCH_HAS_KEEPINITRD
278 bool
279
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280# Select if arch has all set_memory_ro/rw/x/nx() functions in asm/cacheflush.h
281config ARCH_HAS_SET_MEMORY
282 bool
283
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284# Select if arch has all set_direct_map_invalid/default() functions
285config ARCH_HAS_SET_DIRECT_MAP
286 bool
287
c30700db 288#
fa7e2247 289# Select if the architecture provides the arch_dma_set_uncached symbol to
a86ecfa6 290# either provide an uncached segment alias for a DMA allocation, or
fa7e2247 291# to remap the page tables in place.
c30700db 292#
fa7e2247 293config ARCH_HAS_DMA_SET_UNCACHED
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CH
294 bool
295
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CH
296#
297# Select if the architectures provides the arch_dma_clear_uncached symbol
298# to undo an in-place page table remap for uncached access.
299#
300config ARCH_HAS_DMA_CLEAR_UNCACHED
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CH
301 bool
302
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303# Select if arch init_task must go in the __init_task_data section
304config ARCH_TASK_STRUCT_ON_STACK
24b54fee 305 bool
a4a2eb49 306
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TG
307# Select if arch has its private alloc_task_struct() function
308config ARCH_TASK_STRUCT_ALLOCATOR
309 bool
310
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KC
311config HAVE_ARCH_THREAD_STRUCT_WHITELIST
312 bool
313 depends on !ARCH_TASK_STRUCT_ALLOCATOR
314 help
315 An architecture should select this to provide hardened usercopy
316 knowledge about what region of the thread_struct should be
317 whitelisted for copying to userspace. Normally this is only the
318 FPU registers. Specifically, arch_thread_struct_whitelist()
319 should be implemented. Without this, the entire thread_struct
320 field in task_struct will be left whitelisted.
321
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322# Select if arch has its private alloc_thread_stack() function
323config ARCH_THREAD_STACK_ALLOCATOR
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324 bool
325
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IM
326# Select if arch wants to size task_struct dynamically via arch_task_struct_size:
327config ARCH_WANTS_DYNAMIC_TASK_STRUCT
328 bool
329
51c2ee6d
ND
330config ARCH_WANTS_NO_INSTR
331 bool
332 help
333 An architecture should select this if the noinstr macro is being used on
334 functions to denote that the toolchain should avoid instrumenting such
335 functions and is required for correctness.
336
942fa985
YN
337config ARCH_32BIT_OFF_T
338 bool
339 depends on !64BIT
340 help
341 All new 32-bit architectures should have 64-bit off_t type on
342 userspace side which corresponds to the loff_t kernel type. This
343 is the requirement for modern ABIs. Some existing architectures
344 still support 32-bit off_t. This option is enabled for all such
345 architectures explicitly.
346
96c0a6a7
HC
347# Selected by 64 bit architectures which have a 32 bit f_tinode in struct ustat
348config ARCH_32BIT_USTAT_F_TINODE
349 bool
350
2ff2b7ec
MY
351config HAVE_ASM_MODVERSIONS
352 bool
353 help
a86ecfa6 354 This symbol should be selected by an architecture if it provides
2ff2b7ec
MY
355 <asm/asm-prototypes.h> to support the module versioning for symbols
356 exported from assembly code.
357
f850c30c
HC
358config HAVE_REGS_AND_STACK_ACCESS_API
359 bool
e01292b1 360 help
a86ecfa6 361 This symbol should be selected by an architecture if it supports
e01292b1
HC
362 the API needed to access registers and stack entries from pt_regs,
363 declared in asm/ptrace.h
364 For example the kprobes-based event tracer needs this API.
f850c30c 365
d7822b1e
MD
366config HAVE_RSEQ
367 bool
368 depends on HAVE_REGS_AND_STACK_ACCESS_API
369 help
370 This symbol should be selected by an architecture if it
371 supports an implementation of restartable sequences.
372
2f7ab126
MO
373config HAVE_RUST
374 bool
375 help
376 This symbol should be selected by an architecture if it
377 supports Rust.
378
3c88ee19
MH
379config HAVE_FUNCTION_ARG_ACCESS_API
380 bool
381 help
a86ecfa6 382 This symbol should be selected by an architecture if it supports
3c88ee19
MH
383 the API needed to access function arguments from pt_regs,
384 declared in asm/ptrace.h
385
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P
386config HAVE_HW_BREAKPOINT
387 bool
99e8c5a3 388 depends on PERF_EVENTS
62a038d3 389
0102752e
FW
390config HAVE_MIXED_BREAKPOINTS_REGS
391 bool
392 depends on HAVE_HW_BREAKPOINT
393 help
394 Depending on the arch implementation of hardware breakpoints,
395 some of them have separate registers for data and instruction
396 breakpoints addresses, others have mixed registers to store
397 them but define the access type in a control register.
398 Select this option if your arch implements breakpoints under the
399 latter fashion.
400
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AK
401config HAVE_USER_RETURN_NOTIFIER
402 bool
a1922ed6 403
c01d4323
FW
404config HAVE_PERF_EVENTS_NMI
405 bool
23637d47
FW
406 help
407 System hardware can generate an NMI using the perf event
408 subsystem. Also has support for calculating CPU cycle events
409 to determine how many clock cycles in a given period.
c01d4323 410
05a4a952
NP
411config HAVE_HARDLOCKUP_DETECTOR_PERF
412 bool
413 depends on HAVE_PERF_EVENTS_NMI
414 help
415 The arch chooses to use the generic perf-NMI-based hardlockup
416 detector. Must define HAVE_PERF_EVENTS_NMI.
417
418config HAVE_NMI_WATCHDOG
419 depends on HAVE_NMI
420 bool
421 help
422 The arch provides a low level NMI watchdog. It provides
423 asm/nmi.h, and defines its own arch_touch_nmi_watchdog().
424
425config HAVE_HARDLOCKUP_DETECTOR_ARCH
426 bool
427 select HAVE_NMI_WATCHDOG
428 help
429 The arch chooses to provide its own hardlockup detector, which is
430 a superset of the HAVE_NMI_WATCHDOG. It also conforms to config
431 interfaces and parameters provided by hardlockup detector subsystem.
432
c5e63197
JO
433config HAVE_PERF_REGS
434 bool
435 help
436 Support selective register dumps for perf events. This includes
437 bit-mapping of each registers and a unique architecture id.
438
c5ebcedb
JO
439config HAVE_PERF_USER_STACK_DUMP
440 bool
441 help
442 Support user stack dumps for perf event samples. This needs
443 access to the user stack pointer which is not unified across
444 architectures.
445
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JB
446config HAVE_ARCH_JUMP_LABEL
447 bool
448
50ff18ab
AB
449config HAVE_ARCH_JUMP_LABEL_RELATIVE
450 bool
451
0d6e24d4
PZ
452config MMU_GATHER_TABLE_FREE
453 bool
454
ff2e6d72 455config MMU_GATHER_RCU_TABLE_FREE
26723911 456 bool
0d6e24d4 457 select MMU_GATHER_TABLE_FREE
26723911 458
3af4bd03 459config MMU_GATHER_PAGE_SIZE
ed6a7935
PZ
460 bool
461
27796d03
PZ
462config MMU_GATHER_NO_RANGE
463 bool
1e9fdf21
PZ
464 select MMU_GATHER_MERGE_VMAS
465
466config MMU_GATHER_NO_FLUSH_CACHE
467 bool
468
469config MMU_GATHER_MERGE_VMAS
470 bool
27796d03 471
580a586c 472config MMU_GATHER_NO_GATHER
952a31c9 473 bool
0d6e24d4 474 depends on MMU_GATHER_TABLE_FREE
952a31c9 475
d53c3dfb
NP
476config ARCH_WANT_IRQS_OFF_ACTIVATE_MM
477 bool
478 help
479 Temporary select until all architectures can be converted to have
480 irqs disabled over activate_mm. Architectures that do IPI based TLB
481 shootdowns should enable this.
482
88e3009b
NP
483# Use normal mm refcounting for MMU_LAZY_TLB kernel thread references.
484# MMU_LAZY_TLB_REFCOUNT=n can improve the scalability of context switching
485# to/from kernel threads when the same mm is running on a lot of CPUs (a large
486# multi-threaded application), by reducing contention on the mm refcount.
487#
488# This can be disabled if the architecture ensures no CPUs are using an mm as a
489# "lazy tlb" beyond its final refcount (i.e., by the time __mmdrop frees the mm
490# or its kernel page tables). This could be arranged by arch_exit_mmap(), or
491# final exit(2) TLB flush, for example.
492#
493# To implement this, an arch *must*:
494# Ensure the _lazy_tlb variants of mmgrab/mmdrop are used when manipulating
495# the lazy tlb reference of a kthread's ->active_mm (non-arch code has been
496# converted already).
497config MMU_LAZY_TLB_REFCOUNT
498 def_bool y
2655421a
NP
499 depends on !MMU_LAZY_TLB_SHOOTDOWN
500
501# This option allows MMU_LAZY_TLB_REFCOUNT=n. It ensures no CPUs are using an
502# mm as a lazy tlb beyond its last reference count, by shooting down these
503# users before the mm is deallocated. __mmdrop() first IPIs all CPUs that may
504# be using the mm as a lazy tlb, so that they may switch themselves to using
505# init_mm for their active mm. mm_cpumask(mm) is used to determine which CPUs
506# may be using mm as a lazy tlb mm.
507#
508# To implement this, an arch *must*:
509# - At the time of the final mmdrop of the mm, ensure mm_cpumask(mm) contains
510# at least all possible CPUs in which the mm is lazy.
511# - It must meet the requirements for MMU_LAZY_TLB_REFCOUNT=n (see above).
512config MMU_LAZY_TLB_SHOOTDOWN
513 bool
88e3009b 514
df013ffb
HY
515config ARCH_HAVE_NMI_SAFE_CMPXCHG
516 bool
517
2e83b879
PM
518config ARCH_HAS_NMI_SAFE_THIS_CPU_OPS
519 bool
520
43570fd2
HC
521config HAVE_ALIGNED_STRUCT_PAGE
522 bool
523 help
524 This makes sure that struct pages are double word aligned and that
525 e.g. the SLUB allocator can perform double word atomic operations
526 on a struct page for better performance. However selecting this
527 might increase the size of a struct page by a word.
528
4156153c
HC
529config HAVE_CMPXCHG_LOCAL
530 bool
531
2565409f
HC
532config HAVE_CMPXCHG_DOUBLE
533 bool
534
77e58496
PM
535config ARCH_WEAK_RELEASE_ACQUIRE
536 bool
537
c1d7e01d
WD
538config ARCH_WANT_IPC_PARSE_VERSION
539 bool
540
541config ARCH_WANT_COMPAT_IPC_PARSE_VERSION
542 bool
543
48b25c43 544config ARCH_WANT_OLD_COMPAT_IPC
c1d7e01d 545 select ARCH_WANT_COMPAT_IPC_PARSE_VERSION
48b25c43
CM
546 bool
547
282a181b
YZ
548config HAVE_ARCH_SECCOMP
549 bool
550 help
551 An arch should select this symbol to support seccomp mode 1 (the fixed
552 syscall policy), and must provide an overrides for __NR_seccomp_sigreturn,
553 and compat syscalls if the asm-generic/seccomp.h defaults need adjustment:
554 - __NR_seccomp_read_32
555 - __NR_seccomp_write_32
556 - __NR_seccomp_exit_32
557 - __NR_seccomp_sigreturn_32
558
e2cfabdf
WD
559config HAVE_ARCH_SECCOMP_FILTER
560 bool
282a181b 561 select HAVE_ARCH_SECCOMP
e2cfabdf 562 help
fb0fadf9 563 An arch should select this symbol if it provides all of these things:
282a181b 564 - all the requirements for HAVE_ARCH_SECCOMP
bb6ea430
WD
565 - syscall_get_arch()
566 - syscall_get_arguments()
567 - syscall_rollback()
568 - syscall_set_return_value()
fb0fadf9
WD
569 - SIGSYS siginfo_t support
570 - secure_computing is called from a ptrace_event()-safe context
571 - secure_computing return value is checked and a return value of -1
572 results in the system call being skipped immediately.
48dc92b9 573 - seccomp syscall wired up
0d8315dd
YZ
574 - if !HAVE_SPARSE_SYSCALL_NR, have SECCOMP_ARCH_NATIVE,
575 SECCOMP_ARCH_NATIVE_NR, SECCOMP_ARCH_NATIVE_NAME defined. If
576 COMPAT is supported, have the SECCOMP_ARCH_COMPAT* defines too.
e2cfabdf 577
282a181b
YZ
578config SECCOMP
579 prompt "Enable seccomp to safely execute untrusted bytecode"
580 def_bool y
581 depends on HAVE_ARCH_SECCOMP
582 help
583 This kernel feature is useful for number crunching applications
584 that may need to handle untrusted bytecode during their
585 execution. By using pipes or other transports made available
586 to the process as file descriptors supporting the read/write
587 syscalls, it's possible to isolate those applications in their
588 own address space using seccomp. Once seccomp is enabled via
589 prctl(PR_SET_SECCOMP) or the seccomp() syscall, it cannot be
590 disabled and the task is only allowed to execute a few safe
591 syscalls defined by each seccomp mode.
592
593 If unsure, say Y.
594
e2cfabdf
WD
595config SECCOMP_FILTER
596 def_bool y
597 depends on HAVE_ARCH_SECCOMP_FILTER && SECCOMP && NET
598 help
599 Enable tasks to build secure computing environments defined
600 in terms of Berkeley Packet Filter programs which implement
601 task-defined system call filtering polices.
602
5fb94e9c 603 See Documentation/userspace-api/seccomp_filter.rst for details.
e2cfabdf 604
0d8315dd
YZ
605config SECCOMP_CACHE_DEBUG
606 bool "Show seccomp filter cache status in /proc/pid/seccomp_cache"
607 depends on SECCOMP_FILTER && !HAVE_SPARSE_SYSCALL_NR
608 depends on PROC_FS
609 help
610 This enables the /proc/pid/seccomp_cache interface to monitor
611 seccomp cache data. The file format is subject to change. Reading
612 the file requires CAP_SYS_ADMIN.
613
614 This option is for debugging only. Enabling presents the risk that
615 an adversary may be able to infer the seccomp filter logic.
616
617 If unsure, say N.
618
afaef01c
AP
619config HAVE_ARCH_STACKLEAK
620 bool
621 help
622 An architecture should select this if it has the code which
623 fills the used part of the kernel stack with the STACKLEAK_POISON
624 value before returning from system calls.
625
d148eac0 626config HAVE_STACKPROTECTOR
19952a92
KC
627 bool
628 help
629 An arch should select this symbol if:
19952a92
KC
630 - it has implemented a stack canary (e.g. __stack_chk_guard)
631
050e9baa 632config STACKPROTECTOR
2a61f474 633 bool "Stack Protector buffer overflow detection"
d148eac0 634 depends on HAVE_STACKPROTECTOR
2a61f474
MY
635 depends on $(cc-option,-fstack-protector)
636 default y
19952a92 637 help
8779657d 638 This option turns on the "stack-protector" GCC feature. This
19952a92
KC
639 feature puts, at the beginning of functions, a canary value on
640 the stack just before the return address, and validates
641 the value just before actually returning. Stack based buffer
642 overflows (that need to overwrite this return address) now also
643 overwrite the canary, which gets detected and the attack is then
644 neutralized via a kernel panic.
645
8779657d
KC
646 Functions will have the stack-protector canary logic added if they
647 have an 8-byte or larger character array on the stack.
648
19952a92 649 This feature requires gcc version 4.2 or above, or a distribution
8779657d
KC
650 gcc with the feature backported ("-fstack-protector").
651
652 On an x86 "defconfig" build, this feature adds canary checks to
653 about 3% of all kernel functions, which increases kernel code size
654 by about 0.3%.
655
050e9baa 656config STACKPROTECTOR_STRONG
2a61f474 657 bool "Strong Stack Protector"
050e9baa 658 depends on STACKPROTECTOR
2a61f474
MY
659 depends on $(cc-option,-fstack-protector-strong)
660 default y
8779657d
KC
661 help
662 Functions will have the stack-protector canary logic added in any
663 of the following conditions:
664
665 - local variable's address used as part of the right hand side of an
666 assignment or function argument
667 - local variable is an array (or union containing an array),
668 regardless of array type or length
669 - uses register local variables
670
671 This feature requires gcc version 4.9 or above, or a distribution
672 gcc with the feature backported ("-fstack-protector-strong").
673
674 On an x86 "defconfig" build, this feature adds canary checks to
675 about 20% of all kernel functions, which increases the kernel code
676 size by about 2%.
677
d08b9f0c
ST
678config ARCH_SUPPORTS_SHADOW_CALL_STACK
679 bool
680 help
afcf5441
DL
681 An architecture should select this if it supports the compiler's
682 Shadow Call Stack and implements runtime support for shadow stack
aa7a65ae 683 switching.
d08b9f0c
ST
684
685config SHADOW_CALL_STACK
afcf5441
DL
686 bool "Shadow Call Stack"
687 depends on ARCH_SUPPORTS_SHADOW_CALL_STACK
38792972 688 depends on DYNAMIC_FTRACE_WITH_ARGS || DYNAMIC_FTRACE_WITH_REGS || !FUNCTION_GRAPH_TRACER
d08b9f0c 689 help
afcf5441
DL
690 This option enables the compiler's Shadow Call Stack, which
691 uses a shadow stack to protect function return addresses from
692 being overwritten by an attacker. More information can be found
693 in the compiler's documentation:
d08b9f0c 694
afcf5441
DL
695 - Clang: https://clang.llvm.org/docs/ShadowCallStack.html
696 - GCC: https://gcc.gnu.org/onlinedocs/gcc/Instrumentation-Options.html#Instrumentation-Options
d08b9f0c
ST
697
698 Note that security guarantees in the kernel differ from the
699 ones documented for user space. The kernel must store addresses
700 of shadow stacks in memory, which means an attacker capable of
701 reading and writing arbitrary memory may be able to locate them
702 and hijack control flow by modifying the stacks.
703
9beccca0
AB
704config DYNAMIC_SCS
705 bool
706 help
707 Set by the arch code if it relies on code patching to insert the
708 shadow call stack push and pop instructions rather than on the
709 compiler.
710
dc5723b0
ST
711config LTO
712 bool
713 help
714 Selected if the kernel will be built using the compiler's LTO feature.
715
716config LTO_CLANG
717 bool
718 select LTO
719 help
720 Selected if the kernel will be built using Clang's LTO feature.
721
722config ARCH_SUPPORTS_LTO_CLANG
723 bool
724 help
725 An architecture should select this option if it supports:
726 - compiling with Clang,
727 - compiling inline assembly with Clang's integrated assembler,
728 - and linking with LLD.
729
730config ARCH_SUPPORTS_LTO_CLANG_THIN
731 bool
732 help
733 An architecture should select this option if it can support Clang's
734 ThinLTO mode.
735
736config HAS_LTO_CLANG
737 def_bool y
1e68a8af 738 depends on CC_IS_CLANG && LD_IS_LLD && AS_IS_LLVM
dc5723b0
ST
739 depends on $(success,$(NM) --help | head -n 1 | grep -qi llvm)
740 depends on $(success,$(AR) --help | head -n 1 | grep -qi llvm)
741 depends on ARCH_SUPPORTS_LTO_CLANG
742 depends on !FTRACE_MCOUNT_USE_RECORDMCOUNT
bf3c2551 743 depends on !KASAN || KASAN_HW_TAGS
dc5723b0 744 depends on !GCOV_KERNEL
dc5723b0
ST
745 help
746 The compiler and Kconfig options support building with Clang's
747 LTO.
748
749choice
750 prompt "Link Time Optimization (LTO)"
751 default LTO_NONE
752 help
753 This option enables Link Time Optimization (LTO), which allows the
754 compiler to optimize binaries globally.
755
756 If unsure, select LTO_NONE. Note that LTO is very resource-intensive
757 so it's disabled by default.
758
759config LTO_NONE
760 bool "None"
761 help
762 Build the kernel normally, without Link Time Optimization (LTO).
763
764config LTO_CLANG_FULL
765 bool "Clang Full LTO (EXPERIMENTAL)"
766 depends on HAS_LTO_CLANG
767 depends on !COMPILE_TEST
768 select LTO_CLANG
769 help
9f79ffc1
JH
770 This option enables Clang's full Link Time Optimization (LTO), which
771 allows the compiler to optimize the kernel globally. If you enable
772 this option, the compiler generates LLVM bitcode instead of ELF
773 object files, and the actual compilation from bitcode happens at
774 the LTO link step, which may take several minutes depending on the
775 kernel configuration. More information can be found from LLVM's
776 documentation:
dc5723b0
ST
777
778 https://llvm.org/docs/LinkTimeOptimization.html
779
780 During link time, this option can use a large amount of RAM, and
781 may take much longer than the ThinLTO option.
782
783config LTO_CLANG_THIN
784 bool "Clang ThinLTO (EXPERIMENTAL)"
785 depends on HAS_LTO_CLANG && ARCH_SUPPORTS_LTO_CLANG_THIN
786 select LTO_CLANG
787 help
788 This option enables Clang's ThinLTO, which allows for parallel
789 optimization and faster incremental compiles compared to the
790 CONFIG_LTO_CLANG_FULL option. More information can be found
791 from Clang's documentation:
792
793 https://clang.llvm.org/docs/ThinLTO.html
794
795 If unsure, say Y.
796endchoice
797
cf68fffb
ST
798config ARCH_SUPPORTS_CFI_CLANG
799 bool
800 help
801 An architecture should select this option if it can support Clang's
802 Control-Flow Integrity (CFI) checking.
803
89245600
ST
804config ARCH_USES_CFI_TRAPS
805 bool
806
cf68fffb
ST
807config CFI_CLANG
808 bool "Use Clang's Control Flow Integrity (CFI)"
89245600
ST
809 depends on ARCH_SUPPORTS_CFI_CLANG
810 depends on $(cc-option,-fsanitize=kcfi)
cf68fffb
ST
811 help
812 This option enables Clang’s forward-edge Control Flow Integrity
813 (CFI) checking, where the compiler injects a runtime check to each
814 indirect function call to ensure the target is a valid function with
815 the correct static type. This restricts possible call targets and
816 makes it more difficult for an attacker to exploit bugs that allow
817 the modification of stored function pointers. More information can be
818 found from Clang's documentation:
819
820 https://clang.llvm.org/docs/ControlFlowIntegrity.html
821
cf68fffb
ST
822config CFI_PERMISSIVE
823 bool "Use CFI in permissive mode"
824 depends on CFI_CLANG
825 help
826 When selected, Control Flow Integrity (CFI) violations result in a
827 warning instead of a kernel panic. This option should only be used
828 for finding indirect call type mismatches during development.
829
830 If unsure, say N.
831
0f60a8ef
KC
832config HAVE_ARCH_WITHIN_STACK_FRAMES
833 bool
834 help
835 An architecture should select this if it can walk the kernel stack
836 frames to determine if an object is part of either the arguments
837 or local variables (i.e. that it excludes saved return addresses,
838 and similar) by implementing an inline arch_within_stack_frames(),
839 which is used by CONFIG_HARDENED_USERCOPY.
840
24a9c541 841config HAVE_CONTEXT_TRACKING_USER
2b1d5024
FW
842 bool
843 help
91d1aa43
FW
844 Provide kernel/user boundaries probes necessary for subsystems
845 that need it, such as userspace RCU extended quiescent state.
490f561b
FW
846 Syscalls need to be wrapped inside user_exit()-user_enter(), either
847 optimized behind static key or through the slow path using TIF_NOHZ
848 flag. Exceptions handlers must be wrapped as well. Irqs are already
6f0e6c15 849 protected inside ct_irq_enter/ct_irq_exit() but preemption or signal
490f561b
FW
850 handling on irq exit still need to be protected.
851
24a9c541 852config HAVE_CONTEXT_TRACKING_USER_OFFSTACK
83c2da2e
FW
853 bool
854 help
855 Architecture neither relies on exception_enter()/exception_exit()
856 nor on schedule_user(). Also preempt_schedule_notrace() and
857 preempt_schedule_irq() can't be called in a preemptible section
858 while context tracking is CONTEXT_USER. This feature reflects a sane
859 entry implementation where the following requirements are met on
860 critical entry code, ie: before user_exit() or after user_enter():
861
862 - Critical entry code isn't preemptible (or better yet:
863 not interruptible).
493c1822 864 - No use of RCU read side critical sections, unless ct_nmi_enter()
83c2da2e
FW
865 got called.
866 - No use of instrumentation, unless instrumentation_begin() got
867 called.
868
490f561b
FW
869config HAVE_TIF_NOHZ
870 bool
871 help
872 Arch relies on TIF_NOHZ and syscall slow path to implement context
873 tracking calls to user_enter()/user_exit().
2b1d5024 874
b952741c
FW
875config HAVE_VIRT_CPU_ACCOUNTING
876 bool
877
2b91ec9f
FW
878config HAVE_VIRT_CPU_ACCOUNTING_IDLE
879 bool
880 help
881 Architecture has its own way to account idle CPU time and therefore
882 doesn't implement vtime_account_idle().
883
40565b5a
SG
884config ARCH_HAS_SCALED_CPUTIME
885 bool
886
554b0004
KH
887config HAVE_VIRT_CPU_ACCOUNTING_GEN
888 bool
889 default y if 64BIT
890 help
891 With VIRT_CPU_ACCOUNTING_GEN, cputime_t becomes 64-bit.
892 Before enabling this option, arch code must be audited
893 to ensure there are no races in concurrent read/write of
894 cputime_t. For example, reading/writing 64-bit cputime_t on
895 some 32-bit arches may require multiple accesses, so proper
896 locking is needed to protect against concurrent accesses.
897
fdf9c356
FW
898config HAVE_IRQ_TIME_ACCOUNTING
899 bool
900 help
901 Archs need to ensure they use a high enough resolution clock to
902 support irq time accounting and then call enable_sched_clock_irqtime().
903
c49dd340
KS
904config HAVE_MOVE_PUD
905 bool
906 help
907 Architectures that select this are able to move page tables at the
908 PUD level. If there are only 3 page table levels, the move effectively
909 happens at the PGD level.
910
2c91bd4a
JFG
911config HAVE_MOVE_PMD
912 bool
913 help
914 Archs that select this are able to move page tables at the PMD level.
915
15626062
GS
916config HAVE_ARCH_TRANSPARENT_HUGEPAGE
917 bool
918
a00cc7d9
MW
919config HAVE_ARCH_TRANSPARENT_HUGEPAGE_PUD
920 bool
921
0ddab1d2
TK
922config HAVE_ARCH_HUGE_VMAP
923 bool
924
121e6f32
NP
925#
926# Archs that select this would be capable of PMD-sized vmaps (i.e.,
559089e0
SL
927# arch_vmap_pmd_supported() returns true). The VM_ALLOW_HUGE_VMAP flag
928# must be used to enable allocations to use hugepages.
121e6f32
NP
929#
930config HAVE_ARCH_HUGE_VMALLOC
931 depends on HAVE_ARCH_HUGE_VMAP
932 bool
933
3876d4a3
AG
934config ARCH_WANT_HUGE_PMD_SHARE
935 bool
936
0f8975ec
PE
937config HAVE_ARCH_SOFT_DIRTY
938 bool
939
786d35d4
DH
940config HAVE_MOD_ARCH_SPECIFIC
941 bool
942 help
943 The arch uses struct mod_arch_specific to store data. Many arches
944 just need a simple module loader without arch specific data - those
945 should not enable this.
946
947config MODULES_USE_ELF_RELA
948 bool
949 help
950 Modules only use ELF RELA relocations. Modules with ELF REL
951 relocations will give an error.
952
953config MODULES_USE_ELF_REL
954 bool
955 help
956 Modules only use ELF REL relocations. Modules with ELF RELA
957 relocations will give an error.
958
01dc0386
CL
959config ARCH_WANTS_MODULES_DATA_IN_VMALLOC
960 bool
961 help
962 For architectures like powerpc/32 which have constraints on module
963 allocation and need to allocate module data outside of module area.
964
cc1f0274
FW
965config HAVE_IRQ_EXIT_ON_IRQ_STACK
966 bool
967 help
968 Architecture doesn't only execute the irq handler on the irq stack
969 but also irq_exit(). This way we can process softirqs on this irq
970 stack instead of switching to a new one when we call __do_softirq()
971 in the end of an hardirq.
972 This spares a stack switch and improves cache usage on softirq
973 processing.
974
cd1a41ce
TG
975config HAVE_SOFTIRQ_ON_OWN_STACK
976 bool
977 help
978 Architecture provides a function to run __do_softirq() on a
c226bc3c 979 separate stack.
cd1a41ce 980
8cbb2b50
SAS
981config SOFTIRQ_ON_OWN_STACK
982 def_bool HAVE_SOFTIRQ_ON_OWN_STACK && !PREEMPT_RT
983
12700c17
AB
984config ALTERNATE_USER_ADDRESS_SPACE
985 bool
986 help
987 Architectures set this when the CPU uses separate address
988 spaces for kernel and user space pointers. In this case, the
989 access_ok() check on a __user pointer is skipped.
990
235a8f02
KS
991config PGTABLE_LEVELS
992 int
993 default 2
994
2b68f6ca
KC
995config ARCH_HAS_ELF_RANDOMIZE
996 bool
997 help
998 An architecture supports choosing randomized locations for
999 stack, mmap, brk, and ET_DYN. Defined functions:
1000 - arch_mmap_rnd()
204db6ed 1001 - arch_randomize_brk()
2b68f6ca 1002
d07e2259
DC
1003config HAVE_ARCH_MMAP_RND_BITS
1004 bool
1005 help
1006 An arch should select this symbol if it supports setting a variable
1007 number of bits for use in establishing the base address for mmap
1008 allocations, has MMU enabled and provides values for both:
1009 - ARCH_MMAP_RND_BITS_MIN
1010 - ARCH_MMAP_RND_BITS_MAX
1011
5f56a5df
JS
1012config HAVE_EXIT_THREAD
1013 bool
1014 help
1015 An architecture implements exit_thread.
1016
d07e2259
DC
1017config ARCH_MMAP_RND_BITS_MIN
1018 int
1019
1020config ARCH_MMAP_RND_BITS_MAX
1021 int
1022
1023config ARCH_MMAP_RND_BITS_DEFAULT
1024 int
1025
1026config ARCH_MMAP_RND_BITS
1027 int "Number of bits to use for ASLR of mmap base address" if EXPERT
1028 range ARCH_MMAP_RND_BITS_MIN ARCH_MMAP_RND_BITS_MAX
1029 default ARCH_MMAP_RND_BITS_DEFAULT if ARCH_MMAP_RND_BITS_DEFAULT
1030 default ARCH_MMAP_RND_BITS_MIN
1031 depends on HAVE_ARCH_MMAP_RND_BITS
1032 help
1033 This value can be used to select the number of bits to use to
1034 determine the random offset to the base address of vma regions
1035 resulting from mmap allocations. This value will be bounded
1036 by the architecture's minimum and maximum supported values.
1037
1038 This value can be changed after boot using the
1039 /proc/sys/vm/mmap_rnd_bits tunable
1040
1041config HAVE_ARCH_MMAP_RND_COMPAT_BITS
1042 bool
1043 help
1044 An arch should select this symbol if it supports running applications
1045 in compatibility mode, supports setting a variable number of bits for
1046 use in establishing the base address for mmap allocations, has MMU
1047 enabled and provides values for both:
1048 - ARCH_MMAP_RND_COMPAT_BITS_MIN
1049 - ARCH_MMAP_RND_COMPAT_BITS_MAX
1050
1051config ARCH_MMAP_RND_COMPAT_BITS_MIN
1052 int
1053
1054config ARCH_MMAP_RND_COMPAT_BITS_MAX
1055 int
1056
1057config ARCH_MMAP_RND_COMPAT_BITS_DEFAULT
1058 int
1059
1060config ARCH_MMAP_RND_COMPAT_BITS
1061 int "Number of bits to use for ASLR of mmap base address for compatible applications" if EXPERT
1062 range ARCH_MMAP_RND_COMPAT_BITS_MIN ARCH_MMAP_RND_COMPAT_BITS_MAX
1063 default ARCH_MMAP_RND_COMPAT_BITS_DEFAULT if ARCH_MMAP_RND_COMPAT_BITS_DEFAULT
1064 default ARCH_MMAP_RND_COMPAT_BITS_MIN
1065 depends on HAVE_ARCH_MMAP_RND_COMPAT_BITS
1066 help
1067 This value can be used to select the number of bits to use to
1068 determine the random offset to the base address of vma regions
1069 resulting from mmap allocations for compatible applications This
1070 value will be bounded by the architecture's minimum and maximum
1071 supported values.
1072
1073 This value can be changed after boot using the
1074 /proc/sys/vm/mmap_rnd_compat_bits tunable
1075
1b028f78
DS
1076config HAVE_ARCH_COMPAT_MMAP_BASES
1077 bool
1078 help
1079 This allows 64bit applications to invoke 32-bit mmap() syscall
1080 and vice-versa 32-bit applications to call 64-bit mmap().
1081 Required for applications doing different bitness syscalls.
1082
1f0e290c
GR
1083config PAGE_SIZE_LESS_THAN_64KB
1084 def_bool y
1085 depends on !ARM64_64K_PAGES
1086 depends on !IA64_PAGE_SIZE_64KB
1087 depends on !PAGE_SIZE_64KB
1088 depends on !PARISC_PAGE_SIZE_64KB
e4bbd20d
NC
1089 depends on PAGE_SIZE_LESS_THAN_256KB
1090
1091config PAGE_SIZE_LESS_THAN_256KB
1092 def_bool y
1f0e290c
GR
1093 depends on !PAGE_SIZE_256KB
1094
67f3977f
AG
1095# This allows to use a set of generic functions to determine mmap base
1096# address by giving priority to top-down scheme only if the process
1097# is not in legacy mode (compat task, unlimited stack size or
1098# sysctl_legacy_va_layout).
1099# Architecture that selects this option can provide its own version of:
1100# - STACK_RND_MASK
1101config ARCH_WANT_DEFAULT_TOPDOWN_MMAP_LAYOUT
1102 bool
1103 depends on MMU
e7142bf5 1104 select ARCH_HAS_ELF_RANDOMIZE
67f3977f 1105
03f16cd0
JP
1106config HAVE_OBJTOOL
1107 bool
1108
4ab7674f
JP
1109config HAVE_JUMP_LABEL_HACK
1110 bool
1111
22102f45
JP
1112config HAVE_NOINSTR_HACK
1113 bool
1114
489e355b
JP
1115config HAVE_NOINSTR_VALIDATION
1116 bool
1117
5f3da8c0
JP
1118config HAVE_UACCESS_VALIDATION
1119 bool
1120 select OBJTOOL
1121
b9ab5ebb
JP
1122config HAVE_STACK_VALIDATION
1123 bool
1124 help
03f16cd0
JP
1125 Architecture supports objtool compile-time frame pointer rule
1126 validation.
b9ab5ebb 1127
af085d90
JP
1128config HAVE_RELIABLE_STACKTRACE
1129 bool
1130 help
140d7e88
MB
1131 Architecture has either save_stack_trace_tsk_reliable() or
1132 arch_stack_walk_reliable() function which only returns a stack trace
1133 if it can guarantee the trace is reliable.
af085d90 1134
468a9428
GS
1135config HAVE_ARCH_HASH
1136 bool
1137 default n
1138 help
1139 If this is set, the architecture provides an <asm/hash.h>
1140 file which provides platform-specific implementations of some
1141 functions in <linux/hash.h> or fs/namei.c.
1142
666047fe
FT
1143config HAVE_ARCH_NVRAM_OPS
1144 bool
1145
3a495511
WBG
1146config ISA_BUS_API
1147 def_bool ISA
1148
d2125043
AV
1149#
1150# ABI hall of shame
1151#
1152config CLONE_BACKWARDS
1153 bool
1154 help
1155 Architecture has tls passed as the 4th argument of clone(2),
1156 not the 5th one.
1157
1158config CLONE_BACKWARDS2
1159 bool
1160 help
1161 Architecture has the first two arguments of clone(2) swapped.
1162
dfa9771a
MS
1163config CLONE_BACKWARDS3
1164 bool
1165 help
1166 Architecture has tls passed as the 3rd argument of clone(2),
1167 not the 5th one.
1168
eaca6eae
AV
1169config ODD_RT_SIGACTION
1170 bool
1171 help
1172 Architecture has unusual rt_sigaction(2) arguments
1173
0a0e8cdf
AV
1174config OLD_SIGSUSPEND
1175 bool
1176 help
1177 Architecture has old sigsuspend(2) syscall, of one-argument variety
1178
1179config OLD_SIGSUSPEND3
1180 bool
1181 help
1182 Even weirder antique ABI - three-argument sigsuspend(2)
1183
495dfbf7
AV
1184config OLD_SIGACTION
1185 bool
1186 help
1187 Architecture has old sigaction(2) syscall. Nope, not the same
1188 as OLD_SIGSUSPEND | OLD_SIGSUSPEND3 - alpha has sigsuspend(2),
1189 but fairly different variant of sigaction(2), thanks to OSF/1
1190 compatibility...
1191
1192config COMPAT_OLD_SIGACTION
1193 bool
1194
17435e5f 1195config COMPAT_32BIT_TIME
942437c9
AB
1196 bool "Provide system calls for 32-bit time_t"
1197 default !64BIT || COMPAT
17435e5f
DD
1198 help
1199 This enables 32 bit time_t support in addition to 64 bit time_t support.
1200 This is relevant on all 32-bit architectures, and 64-bit architectures
1201 as part of compat syscall handling.
1202
87a4c375
CH
1203config ARCH_NO_PREEMPT
1204 bool
1205
cb2c7d1a
MS
1206config ARCH_EPHEMERAL_INODES
1207 def_bool n
1208 help
1209 An arch should select this symbol if it doesn't keep track of inode
1210 instances on its own, but instead relies on something else (e.g. the
1211 host kernel for an UML kernel).
1212
a50a3f4b
TG
1213config ARCH_SUPPORTS_RT
1214 bool
1215
fff7fb0b
ZZ
1216config CPU_NO_EFFICIENT_FFS
1217 def_bool n
1218
ba14a194
AL
1219config HAVE_ARCH_VMAP_STACK
1220 def_bool n
1221 help
1222 An arch should select this symbol if it can support kernel stacks
1223 in vmalloc space. This means:
1224
1225 - vmalloc space must be large enough to hold many kernel stacks.
1226 This may rule out many 32-bit architectures.
1227
1228 - Stacks in vmalloc space need to work reliably. For example, if
1229 vmap page tables are created on demand, either this mechanism
1230 needs to work while the stack points to a virtual address with
1231 unpopulated page tables or arch code (switch_to() and switch_mm(),
1232 most likely) needs to ensure that the stack's page table entries
1233 are populated before running on a possibly unpopulated stack.
1234
1235 - If the stack overflows into a guard page, something reasonable
1236 should happen. The definition of "reasonable" is flexible, but
1237 instantly rebooting without logging anything would be unfriendly.
1238
1239config VMAP_STACK
1240 default y
1241 bool "Use a virtually-mapped stack"
eafb149e 1242 depends on HAVE_ARCH_VMAP_STACK
38dd767d 1243 depends on !KASAN || KASAN_HW_TAGS || KASAN_VMALLOC
a7f7f624 1244 help
ba14a194
AL
1245 Enable this if you want the use virtually-mapped kernel stacks
1246 with guard pages. This causes kernel stack overflows to be
1247 caught immediately rather than causing difficult-to-diagnose
1248 corruption.
1249
38dd767d
AK
1250 To use this with software KASAN modes, the architecture must support
1251 backing virtual mappings with real shadow memory, and KASAN_VMALLOC
1252 must be enabled.
ba14a194 1253
39218ff4
KC
1254config HAVE_ARCH_RANDOMIZE_KSTACK_OFFSET
1255 def_bool n
1256 help
1257 An arch should select this symbol if it can support kernel stack
1258 offset randomization with calls to add_random_kstack_offset()
1259 during syscall entry and choose_random_kstack_offset() during
1260 syscall exit. Careful removal of -fstack-protector-strong and
1261 -fstack-protector should also be applied to the entry code and
1262 closely examined, as the artificial stack bump looks like an array
1263 to the compiler, so it will attempt to add canary checks regardless
1264 of the static branch state.
1265
8cb37a59
ME
1266config RANDOMIZE_KSTACK_OFFSET
1267 bool "Support for randomizing kernel stack offset on syscall entry" if EXPERT
1268 default y
39218ff4 1269 depends on HAVE_ARCH_RANDOMIZE_KSTACK_OFFSET
efa90c11 1270 depends on INIT_STACK_NONE || !CC_IS_CLANG || CLANG_VERSION >= 140000
39218ff4
KC
1271 help
1272 The kernel stack offset can be randomized (after pt_regs) by
1273 roughly 5 bits of entropy, frustrating memory corruption
1274 attacks that depend on stack address determinism or
8cb37a59
ME
1275 cross-syscall address exposures.
1276
1277 The feature is controlled via the "randomize_kstack_offset=on/off"
1278 kernel boot param, and if turned off has zero overhead due to its use
1279 of static branches (see JUMP_LABEL).
1280
1281 If unsure, say Y.
1282
1283config RANDOMIZE_KSTACK_OFFSET_DEFAULT
1284 bool "Default state of kernel stack offset randomization"
1285 depends on RANDOMIZE_KSTACK_OFFSET
1286 help
1287 Kernel stack offset randomization is controlled by kernel boot param
1288 "randomize_kstack_offset=on/off", and this config chooses the default
1289 boot state.
39218ff4 1290
ad21fc4f
LA
1291config ARCH_OPTIONAL_KERNEL_RWX
1292 def_bool n
1293
1294config ARCH_OPTIONAL_KERNEL_RWX_DEFAULT
1295 def_bool n
1296
1297config ARCH_HAS_STRICT_KERNEL_RWX
1298 def_bool n
1299
0f5bf6d0 1300config STRICT_KERNEL_RWX
ad21fc4f
LA
1301 bool "Make kernel text and rodata read-only" if ARCH_OPTIONAL_KERNEL_RWX
1302 depends on ARCH_HAS_STRICT_KERNEL_RWX
1303 default !ARCH_OPTIONAL_KERNEL_RWX || ARCH_OPTIONAL_KERNEL_RWX_DEFAULT
1304 help
1305 If this is set, kernel text and rodata memory will be made read-only,
1306 and non-text memory will be made non-executable. This provides
1307 protection against certain security exploits (e.g. executing the heap
1308 or modifying text)
1309
1310 These features are considered standard security practice these days.
1311 You should say Y here in almost all cases.
1312
1313config ARCH_HAS_STRICT_MODULE_RWX
1314 def_bool n
1315
0f5bf6d0 1316config STRICT_MODULE_RWX
ad21fc4f
LA
1317 bool "Set loadable kernel module data as NX and text as RO" if ARCH_OPTIONAL_KERNEL_RWX
1318 depends on ARCH_HAS_STRICT_MODULE_RWX && MODULES
1319 default !ARCH_OPTIONAL_KERNEL_RWX || ARCH_OPTIONAL_KERNEL_RWX_DEFAULT
1320 help
1321 If this is set, module text and rodata memory will be made read-only,
1322 and non-text memory will be made non-executable. This provides
1323 protection against certain security exploits (e.g. writing to text)
1324
ea8c64ac
CH
1325# select if the architecture provides an asm/dma-direct.h header
1326config ARCH_HAS_PHYS_TO_DMA
1327 bool
1328
04f264d3
PB
1329config HAVE_ARCH_COMPILER_H
1330 bool
1331 help
1332 An architecture can select this if it provides an
1333 asm/compiler.h header that should be included after
1334 linux/compiler-*.h in order to override macro definitions that those
1335 headers generally provide.
1336
271ca788
AB
1337config HAVE_ARCH_PREL32_RELOCATIONS
1338 bool
1339 help
1340 May be selected by an architecture if it supports place-relative
1341 32-bit relocations, both in the toolchain and in the module loader,
1342 in which case relative references can be used in special sections
1343 for PCI fixup, initcalls etc which are only half the size on 64 bit
1344 architectures, and don't require runtime relocation on relocatable
1345 kernels.
1346
ce9084ba
AB
1347config ARCH_USE_MEMREMAP_PROT
1348 bool
1349
fb346fd9
WL
1350config LOCK_EVENT_COUNTS
1351 bool "Locking event counts collection"
1352 depends on DEBUG_FS
a7f7f624 1353 help
fb346fd9
WL
1354 Enable light-weight counting of various locking related events
1355 in the system with minimal performance impact. This reduces
1356 the chance of application behavior change because of timing
1357 differences. The counts are reported via debugfs.
1358
5cf896fb
PC
1359# Select if the architecture has support for applying RELR relocations.
1360config ARCH_HAS_RELR
1361 bool
1362
1363config RELR
1364 bool "Use RELR relocation packing"
1365 depends on ARCH_HAS_RELR && TOOLS_SUPPORT_RELR
1366 default y
1367 help
1368 Store the kernel's dynamic relocations in the RELR relocation packing
1369 format. Requires a compatible linker (LLD supports this feature), as
1370 well as compatible NM and OBJCOPY utilities (llvm-nm and llvm-objcopy
1371 are compatible).
1372
0c9c1d56
TJB
1373config ARCH_HAS_MEM_ENCRYPT
1374 bool
1375
46b49b12
TL
1376config ARCH_HAS_CC_PLATFORM
1377 bool
1378
0e242208 1379config HAVE_SPARSE_SYSCALL_NR
9f79ffc1
JH
1380 bool
1381 help
1382 An architecture should select this if its syscall numbering is sparse
0e242208
HN
1383 to save space. For example, MIPS architecture has a syscall array with
1384 entries at 4000, 5000 and 6000 locations. This option turns on syscall
1385 related optimizations for a given architecture.
1386
d60d7de3
SS
1387config ARCH_HAS_VDSO_DATA
1388 bool
1389
115284d8
JP
1390config HAVE_STATIC_CALL
1391 bool
1392
9183c3f9
JP
1393config HAVE_STATIC_CALL_INLINE
1394 bool
1395 depends on HAVE_STATIC_CALL
03f16cd0 1396 select OBJTOOL
9183c3f9 1397
6ef869e0
MH
1398config HAVE_PREEMPT_DYNAMIC
1399 bool
99cf983c
MR
1400
1401config HAVE_PREEMPT_DYNAMIC_CALL
1402 bool
6ef869e0 1403 depends on HAVE_STATIC_CALL
99cf983c
MR
1404 select HAVE_PREEMPT_DYNAMIC
1405 help
9f79ffc1
JH
1406 An architecture should select this if it can handle the preemption
1407 model being selected at boot time using static calls.
99cf983c 1408
9f79ffc1
JH
1409 Where an architecture selects HAVE_STATIC_CALL_INLINE, any call to a
1410 preemption function will be patched directly.
99cf983c 1411
9f79ffc1
JH
1412 Where an architecture does not select HAVE_STATIC_CALL_INLINE, any
1413 call to a preemption function will go through a trampoline, and the
1414 trampoline will be patched.
99cf983c 1415
9f79ffc1
JH
1416 It is strongly advised to support inline static call to avoid any
1417 overhead.
99cf983c
MR
1418
1419config HAVE_PREEMPT_DYNAMIC_KEY
1420 bool
a0a12c3e 1421 depends on HAVE_ARCH_JUMP_LABEL
99cf983c 1422 select HAVE_PREEMPT_DYNAMIC
6ef869e0 1423 help
9f79ffc1
JH
1424 An architecture should select this if it can handle the preemption
1425 model being selected at boot time using static keys.
99cf983c 1426
9f79ffc1
JH
1427 Each preemption function will be given an early return based on a
1428 static key. This should have slightly lower overhead than non-inline
1429 static calls, as this effectively inlines each trampoline into the
1430 start of its callee. This may avoid redundant work, and may
1431 integrate better with CFI schemes.
99cf983c 1432
9f79ffc1
JH
1433 This will have greater overhead than using inline static calls as
1434 the call to the preemption function cannot be entirely elided.
6ef869e0 1435
59612b24
NC
1436config ARCH_WANT_LD_ORPHAN_WARN
1437 bool
1438 help
1439 An arch should select this symbol once all linker sections are explicitly
1440 included, size-asserted, or discarded in the linker scripts. This is
1441 important because we never want expected sections to be placed heuristically
1442 by the linker, since the locations of such sections can change between linker
1443 versions.
1444
4f5b0c17
MR
1445config HAVE_ARCH_PFN_VALID
1446 bool
1447
5d6ad668
MR
1448config ARCH_SUPPORTS_DEBUG_PAGEALLOC
1449 bool
1450
df4e817b
PT
1451config ARCH_SUPPORTS_PAGE_TABLE_CHECK
1452 bool
1453
2ca408d9
BG
1454config ARCH_SPLIT_ARG64
1455 bool
1456 help
9f79ffc1
JH
1457 If a 32-bit architecture requires 64-bit arguments to be split into
1458 pairs of 32-bit arguments, select this option.
2ca408d9 1459
7facdc42
AV
1460config ARCH_HAS_ELFCORE_COMPAT
1461 bool
1462
58e106e7
BS
1463config ARCH_HAS_PARANOID_L1D_FLUSH
1464 bool
1465
d593d64f
PS
1466config ARCH_HAVE_TRACE_MMIO_ACCESS
1467 bool
1468
1bdda24c
TG
1469config DYNAMIC_SIGFRAME
1470 bool
1471
50468e43
JS
1472# Select, if arch has a named attribute group bound to NUMA device nodes.
1473config HAVE_ARCH_NODE_DEV_GROUP
1474 bool
1475
eed9a328
YZ
1476config ARCH_HAS_NONLEAF_PMD_YOUNG
1477 bool
1478 help
1479 Architectures that select this option are capable of setting the
1480 accessed bit in non-leaf PMD entries when using them as part of linear
1481 address translations. Page table walkers that clear the accessed bit
1482 may use this capability to reduce their search space.
1483
2521f2c2 1484source "kernel/gcov/Kconfig"
45332b1b
MY
1485
1486source "scripts/gcc-plugins/Kconfig"
fa1b5d09 1487
d49a0626
PZ
1488config FUNCTION_ALIGNMENT_4B
1489 bool
1490
1491config FUNCTION_ALIGNMENT_8B
1492 bool
1493
1494config FUNCTION_ALIGNMENT_16B
1495 bool
1496
1497config FUNCTION_ALIGNMENT_32B
1498 bool
1499
1500config FUNCTION_ALIGNMENT_64B
1501 bool
1502
1503config FUNCTION_ALIGNMENT
1504 int
1505 default 64 if FUNCTION_ALIGNMENT_64B
1506 default 32 if FUNCTION_ALIGNMENT_32B
1507 default 16 if FUNCTION_ALIGNMENT_16B
1508 default 8 if FUNCTION_ALIGNMENT_8B
1509 default 4 if FUNCTION_ALIGNMENT_4B
1510 default 0
1511
22471e13 1512endmenu