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b2441318 1# SPDX-License-Identifier: GPL-2.0
fb32e03f
MD
2#
3# General architecture dependent options
4#
125e5645 5
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CH
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
22471e13
RD
12menu "General architecture-dependent options"
13
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HB
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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TG
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
a631be92
TG
52config HOTPLUG_SPLIT_STARTUP
53 bool
54 select HOTPLUG_CORE_SYNC_FULL
55
18415f33
TG
56config HOTPLUG_PARALLEL
57 bool
58 select HOTPLUG_SPLIT_STARTUP
59
142781e1 60config GENERIC_ENTRY
9f79ffc1 61 bool
142781e1 62
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MD
63config KPROBES
64 bool "Kprobes"
05ed160e 65 depends on MODULES
125e5645 66 depends on HAVE_KPROBES
05ed160e 67 select KALLSYMS
835f14ed 68 select TASKS_RCU if PREEMPTION
125e5645
MD
69 help
70 Kprobes allows you to trap at almost any kernel address and
71 execute a callback function. register_kprobe() establishes
72 a probepoint and specifies the callback. Kprobes is useful
73 for kernel debugging, non-intrusive instrumentation and testing.
74 If in doubt, say "N".
75
45f81b1c 76config JUMP_LABEL
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KK
77 bool "Optimize very unlikely/likely branches"
78 depends on HAVE_ARCH_JUMP_LABEL
4ab7674f 79 select OBJTOOL if HAVE_JUMP_LABEL_HACK
24b54fee 80 help
9f79ffc1
JH
81 This option enables a transparent branch optimization that
82 makes certain almost-always-true or almost-always-false branch
83 conditions even cheaper to execute within the kernel.
c5905afb 84
9f79ffc1
JH
85 Certain performance-sensitive kernel code, such as trace points,
86 scheduler functionality, networking code and KVM have such
87 branches and include support for this optimization technique.
c5905afb 88
9f79ffc1
JH
89 If it is detected that the compiler has support for "asm goto",
90 the kernel will compile such branches with just a nop
91 instruction. When the condition flag is toggled to true, the
92 nop will be converted to a jump instruction to execute the
93 conditional block of instructions.
c5905afb 94
9f79ffc1
JH
95 This technique lowers overhead and stress on the branch prediction
96 of the processor and generally makes the kernel faster. The update
97 of the condition is slower, but those are always very rare.
45f81b1c 98
9f79ffc1
JH
99 ( On 32-bit x86, the necessary options added to the compiler
100 flags may increase the size of the kernel slightly. )
45f81b1c 101
1987c947
PZ
102config STATIC_KEYS_SELFTEST
103 bool "Static key selftest"
104 depends on JUMP_LABEL
105 help
106 Boot time self-test of the branch patching code.
107
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PZ
108config STATIC_CALL_SELFTEST
109 bool "Static call selftest"
110 depends on HAVE_STATIC_CALL
111 help
112 Boot time self-test of the call patching code.
113
afd66255 114config OPTPROBES
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MH
115 def_bool y
116 depends on KPROBES && HAVE_OPTPROBES
01b1d88b 117 select TASKS_RCU if PREEMPTION
afd66255 118
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MH
119config KPROBES_ON_FTRACE
120 def_bool y
121 depends on KPROBES && HAVE_KPROBES_ON_FTRACE
122 depends on DYNAMIC_FTRACE_WITH_REGS
123 help
9f79ffc1
JH
124 If function tracer is enabled and the arch supports full
125 passing of pt_regs to function tracing, then kprobes can
126 optimize on top of function tracing.
e7dbfe34 127
2b144498 128config UPROBES
09294e31 129 def_bool n
e8f4aa60 130 depends on ARCH_SUPPORTS_UPROBES
2b144498 131 help
7b2d81d4
IM
132 Uprobes is the user-space counterpart to kprobes: they
133 enable instrumentation applications (such as 'perf probe')
134 to establish unintrusive probes in user-space binaries and
135 libraries, by executing handler functions when the probes
136 are hit by user-space applications.
137
138 ( These probes come in the form of single-byte breakpoints,
139 managed by the kernel and kept transparent to the probed
140 application. )
2b144498 141
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SRV
142config HAVE_64BIT_ALIGNED_ACCESS
143 def_bool 64BIT && !HAVE_EFFICIENT_UNALIGNED_ACCESS
144 help
145 Some architectures require 64 bit accesses to be 64 bit
146 aligned, which also requires structs containing 64 bit values
147 to be 64 bit aligned too. This includes some 32 bit
148 architectures which can do 64 bit accesses, as well as 64 bit
149 architectures without unaligned access.
150
151 This symbol should be selected by an architecture if 64 bit
152 accesses are required to be 64 bit aligned in this way even
153 though it is not a 64 bit architecture.
154
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155 See Documentation/core-api/unaligned-memory-access.rst for
156 more information on the topic of unaligned memory accesses.
adab66b7 157
58340a07 158config HAVE_EFFICIENT_UNALIGNED_ACCESS
9ba16087 159 bool
58340a07
JB
160 help
161 Some architectures are unable to perform unaligned accesses
162 without the use of get_unaligned/put_unaligned. Others are
163 unable to perform such accesses efficiently (e.g. trap on
164 unaligned access and require fixing it up in the exception
165 handler.)
166
167 This symbol should be selected by an architecture if it can
168 perform unaligned accesses efficiently to allow different
169 code paths to be selected for these cases. Some network
170 drivers, for example, could opt to not fix up alignment
171 problems with received packets if doing so would not help
172 much.
173
c9b54d6f 174 See Documentation/core-api/unaligned-memory-access.rst for more
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JB
175 information on the topic of unaligned memory accesses.
176
cf66bb93 177config ARCH_USE_BUILTIN_BSWAP
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KK
178 bool
179 help
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JH
180 Modern versions of GCC (since 4.4) have builtin functions
181 for handling byte-swapping. Using these, instead of the old
182 inline assembler that the architecture code provides in the
183 __arch_bswapXX() macros, allows the compiler to see what's
184 happening and offers more opportunity for optimisation. In
185 particular, the compiler will be able to combine the byteswap
186 with a nearby load or store and use load-and-swap or
187 store-and-swap instructions if the architecture has them. It
188 should almost *never* result in code which is worse than the
189 hand-coded assembler in <asm/swab.h>. But just in case it
190 does, the use of the builtins is optional.
cf66bb93 191
9f79ffc1
JH
192 Any architecture with load-and-swap or store-and-swap
193 instructions should set this. And it shouldn't hurt to set it
194 on architectures that don't have such instructions.
cf66bb93 195
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AM
196config KRETPROBES
197 def_bool y
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198 depends on KPROBES && (HAVE_KRETPROBES || HAVE_RETHOOK)
199
200config KRETPROBE_ON_RETHOOK
201 def_bool y
202 depends on HAVE_RETHOOK
203 depends on KRETPROBES
204 select RETHOOK
9edddaa2 205
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206config USER_RETURN_NOTIFIER
207 bool
208 depends on HAVE_USER_RETURN_NOTIFIER
209 help
210 Provide a kernel-internal notification when a cpu is about to
211 switch to user mode.
212
28b2ee20 213config HAVE_IOREMAP_PROT
9ba16087 214 bool
28b2ee20 215
125e5645 216config HAVE_KPROBES
9ba16087 217 bool
9edddaa2
AM
218
219config HAVE_KRETPROBES
9ba16087 220 bool
74bc7cee 221
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MH
222config HAVE_OPTPROBES
223 bool
d314d74c 224
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MH
225config HAVE_KPROBES_ON_FTRACE
226 bool
227
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MH
228config ARCH_CORRECT_STACKTRACE_ON_KRETPROBE
229 bool
230 help
231 Since kretprobes modifies return address on the stack, the
232 stacktrace may see the kretprobe trampoline address instead
233 of correct one. If the architecture stacktrace code and
234 unwinder can adjust such entries, select this configuration.
235
540adea3 236config HAVE_FUNCTION_ERROR_INJECTION
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JB
237 bool
238
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239config HAVE_NMI
240 bool
241
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CL
242config HAVE_FUNCTION_DESCRIPTORS
243 bool
244
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MY
245config TRACE_IRQFLAGS_SUPPORT
246 bool
247
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MR
248config TRACE_IRQFLAGS_NMI_SUPPORT
249 bool
250
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RM
251#
252# An arch should select this if it provides all these things:
253#
254# task_pt_regs() in asm/processor.h or asm/ptrace.h
255# arch_has_single_step() if there is hardware single-step support
256# arch_has_block_step() if there is hardware block-step support
1f5a4ad9
RM
257# asm/syscall.h supplying asm-generic/syscall.h interface
258# linux/regset.h user_regset interfaces
259# CORE_DUMP_USE_REGSET #define'd in linux/elf.h
153474ba 260# TIF_SYSCALL_TRACE calls ptrace_report_syscall_{entry,exit}
03248add 261# TIF_NOTIFY_RESUME calls resume_user_mode_work()
1f5a4ad9
RM
262#
263config HAVE_ARCH_TRACEHOOK
9ba16087 264 bool
1f5a4ad9 265
c64be2bb
MS
266config HAVE_DMA_CONTIGUOUS
267 bool
268
29d5e047 269config GENERIC_SMP_IDLE_THREAD
24b54fee 270 bool
29d5e047 271
485cf5da 272config GENERIC_IDLE_POLL_SETUP
24b54fee 273 bool
485cf5da 274
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DM
275config ARCH_HAS_FORTIFY_SOURCE
276 bool
277 help
278 An architecture should select this when it can successfully
279 build and run with CONFIG_FORTIFY_SOURCE.
280
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CH
281#
282# Select if the arch provides a historic keepinit alias for the retain_initrd
283# command line option
284#
285config ARCH_HAS_KEEPINITRD
286 bool
287
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DB
288# Select if arch has all set_memory_ro/rw/x/nx() functions in asm/cacheflush.h
289config ARCH_HAS_SET_MEMORY
290 bool
291
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RE
292# Select if arch has all set_direct_map_invalid/default() functions
293config ARCH_HAS_SET_DIRECT_MAP
294 bool
295
c30700db 296#
fa7e2247 297# Select if the architecture provides the arch_dma_set_uncached symbol to
a86ecfa6 298# either provide an uncached segment alias for a DMA allocation, or
fa7e2247 299# to remap the page tables in place.
c30700db 300#
fa7e2247 301config ARCH_HAS_DMA_SET_UNCACHED
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CH
302 bool
303
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CH
304#
305# Select if the architectures provides the arch_dma_clear_uncached symbol
306# to undo an in-place page table remap for uncached access.
307#
308config ARCH_HAS_DMA_CLEAR_UNCACHED
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CH
309 bool
310
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DH
311# Select if arch init_task must go in the __init_task_data section
312config ARCH_TASK_STRUCT_ON_STACK
24b54fee 313 bool
a4a2eb49 314
f5e10287
TG
315# Select if arch has its private alloc_task_struct() function
316config ARCH_TASK_STRUCT_ALLOCATOR
317 bool
318
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KC
319config HAVE_ARCH_THREAD_STRUCT_WHITELIST
320 bool
321 depends on !ARCH_TASK_STRUCT_ALLOCATOR
322 help
323 An architecture should select this to provide hardened usercopy
324 knowledge about what region of the thread_struct should be
325 whitelisted for copying to userspace. Normally this is only the
326 FPU registers. Specifically, arch_thread_struct_whitelist()
327 should be implemented. Without this, the entire thread_struct
328 field in task_struct will be left whitelisted.
329
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LT
330# Select if arch has its private alloc_thread_stack() function
331config ARCH_THREAD_STACK_ALLOCATOR
f5e10287
TG
332 bool
333
5aaeb5c0
IM
334# Select if arch wants to size task_struct dynamically via arch_task_struct_size:
335config ARCH_WANTS_DYNAMIC_TASK_STRUCT
336 bool
337
51c2ee6d
ND
338config ARCH_WANTS_NO_INSTR
339 bool
340 help
341 An architecture should select this if the noinstr macro is being used on
342 functions to denote that the toolchain should avoid instrumenting such
343 functions and is required for correctness.
344
942fa985
YN
345config ARCH_32BIT_OFF_T
346 bool
347 depends on !64BIT
348 help
349 All new 32-bit architectures should have 64-bit off_t type on
350 userspace side which corresponds to the loff_t kernel type. This
351 is the requirement for modern ABIs. Some existing architectures
352 still support 32-bit off_t. This option is enabled for all such
353 architectures explicitly.
354
96c0a6a7
HC
355# Selected by 64 bit architectures which have a 32 bit f_tinode in struct ustat
356config ARCH_32BIT_USTAT_F_TINODE
357 bool
358
2ff2b7ec
MY
359config HAVE_ASM_MODVERSIONS
360 bool
361 help
a86ecfa6 362 This symbol should be selected by an architecture if it provides
2ff2b7ec
MY
363 <asm/asm-prototypes.h> to support the module versioning for symbols
364 exported from assembly code.
365
f850c30c
HC
366config HAVE_REGS_AND_STACK_ACCESS_API
367 bool
e01292b1 368 help
a86ecfa6 369 This symbol should be selected by an architecture if it supports
e01292b1
HC
370 the API needed to access registers and stack entries from pt_regs,
371 declared in asm/ptrace.h
372 For example the kprobes-based event tracer needs this API.
f850c30c 373
d7822b1e
MD
374config HAVE_RSEQ
375 bool
376 depends on HAVE_REGS_AND_STACK_ACCESS_API
377 help
378 This symbol should be selected by an architecture if it
379 supports an implementation of restartable sequences.
380
2f7ab126
MO
381config HAVE_RUST
382 bool
383 help
384 This symbol should be selected by an architecture if it
385 supports Rust.
386
3c88ee19
MH
387config HAVE_FUNCTION_ARG_ACCESS_API
388 bool
389 help
a86ecfa6 390 This symbol should be selected by an architecture if it supports
3c88ee19
MH
391 the API needed to access function arguments from pt_regs,
392 declared in asm/ptrace.h
393
62a038d3
P
394config HAVE_HW_BREAKPOINT
395 bool
99e8c5a3 396 depends on PERF_EVENTS
62a038d3 397
0102752e
FW
398config HAVE_MIXED_BREAKPOINTS_REGS
399 bool
400 depends on HAVE_HW_BREAKPOINT
401 help
402 Depending on the arch implementation of hardware breakpoints,
403 some of them have separate registers for data and instruction
404 breakpoints addresses, others have mixed registers to store
405 them but define the access type in a control register.
406 Select this option if your arch implements breakpoints under the
407 latter fashion.
408
7c68af6e
AK
409config HAVE_USER_RETURN_NOTIFIER
410 bool
a1922ed6 411
c01d4323
FW
412config HAVE_PERF_EVENTS_NMI
413 bool
23637d47
FW
414 help
415 System hardware can generate an NMI using the perf event
416 subsystem. Also has support for calculating CPU cycle events
417 to determine how many clock cycles in a given period.
c01d4323 418
05a4a952
NP
419config HAVE_HARDLOCKUP_DETECTOR_PERF
420 bool
421 depends on HAVE_PERF_EVENTS_NMI
422 help
423 The arch chooses to use the generic perf-NMI-based hardlockup
424 detector. Must define HAVE_PERF_EVENTS_NMI.
425
426config HAVE_NMI_WATCHDOG
427 depends on HAVE_NMI
428 bool
429 help
430 The arch provides a low level NMI watchdog. It provides
431 asm/nmi.h, and defines its own arch_touch_nmi_watchdog().
432
433config HAVE_HARDLOCKUP_DETECTOR_ARCH
434 bool
435 select HAVE_NMI_WATCHDOG
436 help
437 The arch chooses to provide its own hardlockup detector, which is
438 a superset of the HAVE_NMI_WATCHDOG. It also conforms to config
439 interfaces and parameters provided by hardlockup detector subsystem.
440
c5e63197
JO
441config HAVE_PERF_REGS
442 bool
443 help
444 Support selective register dumps for perf events. This includes
445 bit-mapping of each registers and a unique architecture id.
446
c5ebcedb
JO
447config HAVE_PERF_USER_STACK_DUMP
448 bool
449 help
450 Support user stack dumps for perf event samples. This needs
451 access to the user stack pointer which is not unified across
452 architectures.
453
bf5438fc
JB
454config HAVE_ARCH_JUMP_LABEL
455 bool
456
50ff18ab
AB
457config HAVE_ARCH_JUMP_LABEL_RELATIVE
458 bool
459
0d6e24d4
PZ
460config MMU_GATHER_TABLE_FREE
461 bool
462
ff2e6d72 463config MMU_GATHER_RCU_TABLE_FREE
26723911 464 bool
0d6e24d4 465 select MMU_GATHER_TABLE_FREE
26723911 466
3af4bd03 467config MMU_GATHER_PAGE_SIZE
ed6a7935
PZ
468 bool
469
27796d03
PZ
470config MMU_GATHER_NO_RANGE
471 bool
1e9fdf21
PZ
472 select MMU_GATHER_MERGE_VMAS
473
474config MMU_GATHER_NO_FLUSH_CACHE
475 bool
476
477config MMU_GATHER_MERGE_VMAS
478 bool
27796d03 479
580a586c 480config MMU_GATHER_NO_GATHER
952a31c9 481 bool
0d6e24d4 482 depends on MMU_GATHER_TABLE_FREE
952a31c9 483
d53c3dfb
NP
484config ARCH_WANT_IRQS_OFF_ACTIVATE_MM
485 bool
486 help
487 Temporary select until all architectures can be converted to have
488 irqs disabled over activate_mm. Architectures that do IPI based TLB
489 shootdowns should enable this.
490
88e3009b
NP
491# Use normal mm refcounting for MMU_LAZY_TLB kernel thread references.
492# MMU_LAZY_TLB_REFCOUNT=n can improve the scalability of context switching
493# to/from kernel threads when the same mm is running on a lot of CPUs (a large
494# multi-threaded application), by reducing contention on the mm refcount.
495#
496# This can be disabled if the architecture ensures no CPUs are using an mm as a
497# "lazy tlb" beyond its final refcount (i.e., by the time __mmdrop frees the mm
498# or its kernel page tables). This could be arranged by arch_exit_mmap(), or
499# final exit(2) TLB flush, for example.
500#
501# To implement this, an arch *must*:
502# Ensure the _lazy_tlb variants of mmgrab/mmdrop are used when manipulating
503# the lazy tlb reference of a kthread's ->active_mm (non-arch code has been
504# converted already).
505config MMU_LAZY_TLB_REFCOUNT
506 def_bool y
2655421a
NP
507 depends on !MMU_LAZY_TLB_SHOOTDOWN
508
509# This option allows MMU_LAZY_TLB_REFCOUNT=n. It ensures no CPUs are using an
510# mm as a lazy tlb beyond its last reference count, by shooting down these
511# users before the mm is deallocated. __mmdrop() first IPIs all CPUs that may
512# be using the mm as a lazy tlb, so that they may switch themselves to using
513# init_mm for their active mm. mm_cpumask(mm) is used to determine which CPUs
514# may be using mm as a lazy tlb mm.
515#
516# To implement this, an arch *must*:
517# - At the time of the final mmdrop of the mm, ensure mm_cpumask(mm) contains
518# at least all possible CPUs in which the mm is lazy.
519# - It must meet the requirements for MMU_LAZY_TLB_REFCOUNT=n (see above).
520config MMU_LAZY_TLB_SHOOTDOWN
521 bool
88e3009b 522
df013ffb
YH
523config ARCH_HAVE_NMI_SAFE_CMPXCHG
524 bool
525
2e83b879
PM
526config ARCH_HAS_NMI_SAFE_THIS_CPU_OPS
527 bool
528
43570fd2
HC
529config HAVE_ALIGNED_STRUCT_PAGE
530 bool
531 help
532 This makes sure that struct pages are double word aligned and that
533 e.g. the SLUB allocator can perform double word atomic operations
534 on a struct page for better performance. However selecting this
535 might increase the size of a struct page by a word.
536
4156153c
HC
537config HAVE_CMPXCHG_LOCAL
538 bool
539
2565409f
HC
540config HAVE_CMPXCHG_DOUBLE
541 bool
542
77e58496
PM
543config ARCH_WEAK_RELEASE_ACQUIRE
544 bool
545
c1d7e01d
WD
546config ARCH_WANT_IPC_PARSE_VERSION
547 bool
548
549config ARCH_WANT_COMPAT_IPC_PARSE_VERSION
550 bool
551
48b25c43 552config ARCH_WANT_OLD_COMPAT_IPC
c1d7e01d 553 select ARCH_WANT_COMPAT_IPC_PARSE_VERSION
48b25c43
CM
554 bool
555
282a181b
YZ
556config HAVE_ARCH_SECCOMP
557 bool
558 help
559 An arch should select this symbol to support seccomp mode 1 (the fixed
560 syscall policy), and must provide an overrides for __NR_seccomp_sigreturn,
561 and compat syscalls if the asm-generic/seccomp.h defaults need adjustment:
562 - __NR_seccomp_read_32
563 - __NR_seccomp_write_32
564 - __NR_seccomp_exit_32
565 - __NR_seccomp_sigreturn_32
566
e2cfabdf
WD
567config HAVE_ARCH_SECCOMP_FILTER
568 bool
282a181b 569 select HAVE_ARCH_SECCOMP
e2cfabdf 570 help
fb0fadf9 571 An arch should select this symbol if it provides all of these things:
282a181b 572 - all the requirements for HAVE_ARCH_SECCOMP
bb6ea430
WD
573 - syscall_get_arch()
574 - syscall_get_arguments()
575 - syscall_rollback()
576 - syscall_set_return_value()
fb0fadf9
WD
577 - SIGSYS siginfo_t support
578 - secure_computing is called from a ptrace_event()-safe context
579 - secure_computing return value is checked and a return value of -1
580 results in the system call being skipped immediately.
48dc92b9 581 - seccomp syscall wired up
0d8315dd
YZ
582 - if !HAVE_SPARSE_SYSCALL_NR, have SECCOMP_ARCH_NATIVE,
583 SECCOMP_ARCH_NATIVE_NR, SECCOMP_ARCH_NATIVE_NAME defined. If
584 COMPAT is supported, have the SECCOMP_ARCH_COMPAT* defines too.
e2cfabdf 585
282a181b
YZ
586config SECCOMP
587 prompt "Enable seccomp to safely execute untrusted bytecode"
588 def_bool y
589 depends on HAVE_ARCH_SECCOMP
590 help
591 This kernel feature is useful for number crunching applications
592 that may need to handle untrusted bytecode during their
593 execution. By using pipes or other transports made available
594 to the process as file descriptors supporting the read/write
595 syscalls, it's possible to isolate those applications in their
596 own address space using seccomp. Once seccomp is enabled via
597 prctl(PR_SET_SECCOMP) or the seccomp() syscall, it cannot be
598 disabled and the task is only allowed to execute a few safe
599 syscalls defined by each seccomp mode.
600
601 If unsure, say Y.
602
e2cfabdf
WD
603config SECCOMP_FILTER
604 def_bool y
605 depends on HAVE_ARCH_SECCOMP_FILTER && SECCOMP && NET
606 help
607 Enable tasks to build secure computing environments defined
608 in terms of Berkeley Packet Filter programs which implement
609 task-defined system call filtering polices.
610
5fb94e9c 611 See Documentation/userspace-api/seccomp_filter.rst for details.
e2cfabdf 612
0d8315dd
YZ
613config SECCOMP_CACHE_DEBUG
614 bool "Show seccomp filter cache status in /proc/pid/seccomp_cache"
615 depends on SECCOMP_FILTER && !HAVE_SPARSE_SYSCALL_NR
616 depends on PROC_FS
617 help
618 This enables the /proc/pid/seccomp_cache interface to monitor
619 seccomp cache data. The file format is subject to change. Reading
620 the file requires CAP_SYS_ADMIN.
621
622 This option is for debugging only. Enabling presents the risk that
623 an adversary may be able to infer the seccomp filter logic.
624
625 If unsure, say N.
626
afaef01c
AP
627config HAVE_ARCH_STACKLEAK
628 bool
629 help
630 An architecture should select this if it has the code which
631 fills the used part of the kernel stack with the STACKLEAK_POISON
632 value before returning from system calls.
633
d148eac0 634config HAVE_STACKPROTECTOR
19952a92
KC
635 bool
636 help
637 An arch should select this symbol if:
19952a92
KC
638 - it has implemented a stack canary (e.g. __stack_chk_guard)
639
050e9baa 640config STACKPROTECTOR
2a61f474 641 bool "Stack Protector buffer overflow detection"
d148eac0 642 depends on HAVE_STACKPROTECTOR
2a61f474
MY
643 depends on $(cc-option,-fstack-protector)
644 default y
19952a92 645 help
8779657d 646 This option turns on the "stack-protector" GCC feature. This
19952a92
KC
647 feature puts, at the beginning of functions, a canary value on
648 the stack just before the return address, and validates
649 the value just before actually returning. Stack based buffer
650 overflows (that need to overwrite this return address) now also
651 overwrite the canary, which gets detected and the attack is then
652 neutralized via a kernel panic.
653
8779657d
KC
654 Functions will have the stack-protector canary logic added if they
655 have an 8-byte or larger character array on the stack.
656
19952a92 657 This feature requires gcc version 4.2 or above, or a distribution
8779657d
KC
658 gcc with the feature backported ("-fstack-protector").
659
660 On an x86 "defconfig" build, this feature adds canary checks to
661 about 3% of all kernel functions, which increases kernel code size
662 by about 0.3%.
663
050e9baa 664config STACKPROTECTOR_STRONG
2a61f474 665 bool "Strong Stack Protector"
050e9baa 666 depends on STACKPROTECTOR
2a61f474
MY
667 depends on $(cc-option,-fstack-protector-strong)
668 default y
8779657d
KC
669 help
670 Functions will have the stack-protector canary logic added in any
671 of the following conditions:
672
673 - local variable's address used as part of the right hand side of an
674 assignment or function argument
675 - local variable is an array (or union containing an array),
676 regardless of array type or length
677 - uses register local variables
678
679 This feature requires gcc version 4.9 or above, or a distribution
680 gcc with the feature backported ("-fstack-protector-strong").
681
682 On an x86 "defconfig" build, this feature adds canary checks to
683 about 20% of all kernel functions, which increases the kernel code
684 size by about 2%.
685
d08b9f0c
ST
686config ARCH_SUPPORTS_SHADOW_CALL_STACK
687 bool
688 help
afcf5441
DL
689 An architecture should select this if it supports the compiler's
690 Shadow Call Stack and implements runtime support for shadow stack
aa7a65ae 691 switching.
d08b9f0c
ST
692
693config SHADOW_CALL_STACK
afcf5441
DL
694 bool "Shadow Call Stack"
695 depends on ARCH_SUPPORTS_SHADOW_CALL_STACK
38792972 696 depends on DYNAMIC_FTRACE_WITH_ARGS || DYNAMIC_FTRACE_WITH_REGS || !FUNCTION_GRAPH_TRACER
d08b9f0c 697 help
afcf5441
DL
698 This option enables the compiler's Shadow Call Stack, which
699 uses a shadow stack to protect function return addresses from
700 being overwritten by an attacker. More information can be found
701 in the compiler's documentation:
d08b9f0c 702
afcf5441
DL
703 - Clang: https://clang.llvm.org/docs/ShadowCallStack.html
704 - GCC: https://gcc.gnu.org/onlinedocs/gcc/Instrumentation-Options.html#Instrumentation-Options
d08b9f0c
ST
705
706 Note that security guarantees in the kernel differ from the
707 ones documented for user space. The kernel must store addresses
708 of shadow stacks in memory, which means an attacker capable of
709 reading and writing arbitrary memory may be able to locate them
710 and hijack control flow by modifying the stacks.
711
9beccca0
AB
712config DYNAMIC_SCS
713 bool
714 help
715 Set by the arch code if it relies on code patching to insert the
716 shadow call stack push and pop instructions rather than on the
717 compiler.
718
dc5723b0
ST
719config LTO
720 bool
721 help
722 Selected if the kernel will be built using the compiler's LTO feature.
723
724config LTO_CLANG
725 bool
726 select LTO
727 help
728 Selected if the kernel will be built using Clang's LTO feature.
729
730config ARCH_SUPPORTS_LTO_CLANG
731 bool
732 help
733 An architecture should select this option if it supports:
734 - compiling with Clang,
735 - compiling inline assembly with Clang's integrated assembler,
736 - and linking with LLD.
737
738config ARCH_SUPPORTS_LTO_CLANG_THIN
739 bool
740 help
741 An architecture should select this option if it can support Clang's
742 ThinLTO mode.
743
744config HAS_LTO_CLANG
745 def_bool y
1e68a8af 746 depends on CC_IS_CLANG && LD_IS_LLD && AS_IS_LLVM
dc5723b0
ST
747 depends on $(success,$(NM) --help | head -n 1 | grep -qi llvm)
748 depends on $(success,$(AR) --help | head -n 1 | grep -qi llvm)
749 depends on ARCH_SUPPORTS_LTO_CLANG
750 depends on !FTRACE_MCOUNT_USE_RECORDMCOUNT
bf3c2551 751 depends on !KASAN || KASAN_HW_TAGS
dc5723b0 752 depends on !GCOV_KERNEL
dc5723b0
ST
753 help
754 The compiler and Kconfig options support building with Clang's
755 LTO.
756
757choice
758 prompt "Link Time Optimization (LTO)"
759 default LTO_NONE
760 help
761 This option enables Link Time Optimization (LTO), which allows the
762 compiler to optimize binaries globally.
763
764 If unsure, select LTO_NONE. Note that LTO is very resource-intensive
765 so it's disabled by default.
766
767config LTO_NONE
768 bool "None"
769 help
770 Build the kernel normally, without Link Time Optimization (LTO).
771
772config LTO_CLANG_FULL
773 bool "Clang Full LTO (EXPERIMENTAL)"
774 depends on HAS_LTO_CLANG
775 depends on !COMPILE_TEST
776 select LTO_CLANG
777 help
9f79ffc1
JH
778 This option enables Clang's full Link Time Optimization (LTO), which
779 allows the compiler to optimize the kernel globally. If you enable
780 this option, the compiler generates LLVM bitcode instead of ELF
781 object files, and the actual compilation from bitcode happens at
782 the LTO link step, which may take several minutes depending on the
783 kernel configuration. More information can be found from LLVM's
784 documentation:
dc5723b0
ST
785
786 https://llvm.org/docs/LinkTimeOptimization.html
787
788 During link time, this option can use a large amount of RAM, and
789 may take much longer than the ThinLTO option.
790
791config LTO_CLANG_THIN
792 bool "Clang ThinLTO (EXPERIMENTAL)"
793 depends on HAS_LTO_CLANG && ARCH_SUPPORTS_LTO_CLANG_THIN
794 select LTO_CLANG
795 help
796 This option enables Clang's ThinLTO, which allows for parallel
797 optimization and faster incremental compiles compared to the
798 CONFIG_LTO_CLANG_FULL option. More information can be found
799 from Clang's documentation:
800
801 https://clang.llvm.org/docs/ThinLTO.html
802
803 If unsure, say Y.
804endchoice
805
cf68fffb
ST
806config ARCH_SUPPORTS_CFI_CLANG
807 bool
808 help
809 An architecture should select this option if it can support Clang's
810 Control-Flow Integrity (CFI) checking.
811
89245600
ST
812config ARCH_USES_CFI_TRAPS
813 bool
814
cf68fffb
ST
815config CFI_CLANG
816 bool "Use Clang's Control Flow Integrity (CFI)"
89245600
ST
817 depends on ARCH_SUPPORTS_CFI_CLANG
818 depends on $(cc-option,-fsanitize=kcfi)
cf68fffb
ST
819 help
820 This option enables Clang’s forward-edge Control Flow Integrity
821 (CFI) checking, where the compiler injects a runtime check to each
822 indirect function call to ensure the target is a valid function with
823 the correct static type. This restricts possible call targets and
824 makes it more difficult for an attacker to exploit bugs that allow
825 the modification of stored function pointers. More information can be
826 found from Clang's documentation:
827
828 https://clang.llvm.org/docs/ControlFlowIntegrity.html
829
cf68fffb
ST
830config CFI_PERMISSIVE
831 bool "Use CFI in permissive mode"
832 depends on CFI_CLANG
833 help
834 When selected, Control Flow Integrity (CFI) violations result in a
835 warning instead of a kernel panic. This option should only be used
836 for finding indirect call type mismatches during development.
837
838 If unsure, say N.
839
0f60a8ef
KC
840config HAVE_ARCH_WITHIN_STACK_FRAMES
841 bool
842 help
843 An architecture should select this if it can walk the kernel stack
844 frames to determine if an object is part of either the arguments
845 or local variables (i.e. that it excludes saved return addresses,
846 and similar) by implementing an inline arch_within_stack_frames(),
847 which is used by CONFIG_HARDENED_USERCOPY.
848
24a9c541 849config HAVE_CONTEXT_TRACKING_USER
2b1d5024
FW
850 bool
851 help
91d1aa43
FW
852 Provide kernel/user boundaries probes necessary for subsystems
853 that need it, such as userspace RCU extended quiescent state.
490f561b
FW
854 Syscalls need to be wrapped inside user_exit()-user_enter(), either
855 optimized behind static key or through the slow path using TIF_NOHZ
856 flag. Exceptions handlers must be wrapped as well. Irqs are already
6f0e6c15 857 protected inside ct_irq_enter/ct_irq_exit() but preemption or signal
490f561b
FW
858 handling on irq exit still need to be protected.
859
24a9c541 860config HAVE_CONTEXT_TRACKING_USER_OFFSTACK
83c2da2e
FW
861 bool
862 help
863 Architecture neither relies on exception_enter()/exception_exit()
864 nor on schedule_user(). Also preempt_schedule_notrace() and
865 preempt_schedule_irq() can't be called in a preemptible section
866 while context tracking is CONTEXT_USER. This feature reflects a sane
867 entry implementation where the following requirements are met on
868 critical entry code, ie: before user_exit() or after user_enter():
869
870 - Critical entry code isn't preemptible (or better yet:
871 not interruptible).
493c1822 872 - No use of RCU read side critical sections, unless ct_nmi_enter()
83c2da2e
FW
873 got called.
874 - No use of instrumentation, unless instrumentation_begin() got
875 called.
876
490f561b
FW
877config HAVE_TIF_NOHZ
878 bool
879 help
880 Arch relies on TIF_NOHZ and syscall slow path to implement context
881 tracking calls to user_enter()/user_exit().
2b1d5024 882
b952741c
FW
883config HAVE_VIRT_CPU_ACCOUNTING
884 bool
885
2b91ec9f
FW
886config HAVE_VIRT_CPU_ACCOUNTING_IDLE
887 bool
888 help
889 Architecture has its own way to account idle CPU time and therefore
890 doesn't implement vtime_account_idle().
891
40565b5a
SG
892config ARCH_HAS_SCALED_CPUTIME
893 bool
894
554b0004
KH
895config HAVE_VIRT_CPU_ACCOUNTING_GEN
896 bool
897 default y if 64BIT
898 help
899 With VIRT_CPU_ACCOUNTING_GEN, cputime_t becomes 64-bit.
900 Before enabling this option, arch code must be audited
901 to ensure there are no races in concurrent read/write of
902 cputime_t. For example, reading/writing 64-bit cputime_t on
903 some 32-bit arches may require multiple accesses, so proper
904 locking is needed to protect against concurrent accesses.
905
fdf9c356
FW
906config HAVE_IRQ_TIME_ACCOUNTING
907 bool
908 help
909 Archs need to ensure they use a high enough resolution clock to
910 support irq time accounting and then call enable_sched_clock_irqtime().
911
c49dd340
KS
912config HAVE_MOVE_PUD
913 bool
914 help
915 Architectures that select this are able to move page tables at the
916 PUD level. If there are only 3 page table levels, the move effectively
917 happens at the PGD level.
918
2c91bd4a
JFG
919config HAVE_MOVE_PMD
920 bool
921 help
922 Archs that select this are able to move page tables at the PMD level.
923
15626062
GS
924config HAVE_ARCH_TRANSPARENT_HUGEPAGE
925 bool
926
a00cc7d9
MW
927config HAVE_ARCH_TRANSPARENT_HUGEPAGE_PUD
928 bool
929
0ddab1d2
TK
930config HAVE_ARCH_HUGE_VMAP
931 bool
932
121e6f32
NP
933#
934# Archs that select this would be capable of PMD-sized vmaps (i.e.,
559089e0
SL
935# arch_vmap_pmd_supported() returns true). The VM_ALLOW_HUGE_VMAP flag
936# must be used to enable allocations to use hugepages.
121e6f32
NP
937#
938config HAVE_ARCH_HUGE_VMALLOC
939 depends on HAVE_ARCH_HUGE_VMAP
940 bool
941
3876d4a3
AG
942config ARCH_WANT_HUGE_PMD_SHARE
943 bool
944
0f8975ec
PE
945config HAVE_ARCH_SOFT_DIRTY
946 bool
947
786d35d4
DH
948config HAVE_MOD_ARCH_SPECIFIC
949 bool
950 help
951 The arch uses struct mod_arch_specific to store data. Many arches
952 just need a simple module loader without arch specific data - those
953 should not enable this.
954
955config MODULES_USE_ELF_RELA
956 bool
957 help
958 Modules only use ELF RELA relocations. Modules with ELF REL
959 relocations will give an error.
960
961config MODULES_USE_ELF_REL
962 bool
963 help
964 Modules only use ELF REL relocations. Modules with ELF RELA
965 relocations will give an error.
966
01dc0386
CL
967config ARCH_WANTS_MODULES_DATA_IN_VMALLOC
968 bool
969 help
970 For architectures like powerpc/32 which have constraints on module
971 allocation and need to allocate module data outside of module area.
972
cc1f0274
FW
973config HAVE_IRQ_EXIT_ON_IRQ_STACK
974 bool
975 help
976 Architecture doesn't only execute the irq handler on the irq stack
977 but also irq_exit(). This way we can process softirqs on this irq
978 stack instead of switching to a new one when we call __do_softirq()
979 in the end of an hardirq.
980 This spares a stack switch and improves cache usage on softirq
981 processing.
982
cd1a41ce
TG
983config HAVE_SOFTIRQ_ON_OWN_STACK
984 bool
985 help
986 Architecture provides a function to run __do_softirq() on a
c226bc3c 987 separate stack.
cd1a41ce 988
8cbb2b50
SAS
989config SOFTIRQ_ON_OWN_STACK
990 def_bool HAVE_SOFTIRQ_ON_OWN_STACK && !PREEMPT_RT
991
12700c17
AB
992config ALTERNATE_USER_ADDRESS_SPACE
993 bool
994 help
995 Architectures set this when the CPU uses separate address
996 spaces for kernel and user space pointers. In this case, the
997 access_ok() check on a __user pointer is skipped.
998
235a8f02
KS
999config PGTABLE_LEVELS
1000 int
1001 default 2
1002
2b68f6ca
KC
1003config ARCH_HAS_ELF_RANDOMIZE
1004 bool
1005 help
1006 An architecture supports choosing randomized locations for
1007 stack, mmap, brk, and ET_DYN. Defined functions:
1008 - arch_mmap_rnd()
204db6ed 1009 - arch_randomize_brk()
2b68f6ca 1010
d07e2259
DC
1011config HAVE_ARCH_MMAP_RND_BITS
1012 bool
1013 help
1014 An arch should select this symbol if it supports setting a variable
1015 number of bits for use in establishing the base address for mmap
1016 allocations, has MMU enabled and provides values for both:
1017 - ARCH_MMAP_RND_BITS_MIN
1018 - ARCH_MMAP_RND_BITS_MAX
1019
5f56a5df
JS
1020config HAVE_EXIT_THREAD
1021 bool
1022 help
1023 An architecture implements exit_thread.
1024
d07e2259
DC
1025config ARCH_MMAP_RND_BITS_MIN
1026 int
1027
1028config ARCH_MMAP_RND_BITS_MAX
1029 int
1030
1031config ARCH_MMAP_RND_BITS_DEFAULT
1032 int
1033
1034config ARCH_MMAP_RND_BITS
1035 int "Number of bits to use for ASLR of mmap base address" if EXPERT
1036 range ARCH_MMAP_RND_BITS_MIN ARCH_MMAP_RND_BITS_MAX
1037 default ARCH_MMAP_RND_BITS_DEFAULT if ARCH_MMAP_RND_BITS_DEFAULT
1038 default ARCH_MMAP_RND_BITS_MIN
1039 depends on HAVE_ARCH_MMAP_RND_BITS
1040 help
1041 This value can be used to select the number of bits to use to
1042 determine the random offset to the base address of vma regions
1043 resulting from mmap allocations. This value will be bounded
1044 by the architecture's minimum and maximum supported values.
1045
1046 This value can be changed after boot using the
1047 /proc/sys/vm/mmap_rnd_bits tunable
1048
1049config HAVE_ARCH_MMAP_RND_COMPAT_BITS
1050 bool
1051 help
1052 An arch should select this symbol if it supports running applications
1053 in compatibility mode, supports setting a variable number of bits for
1054 use in establishing the base address for mmap allocations, has MMU
1055 enabled and provides values for both:
1056 - ARCH_MMAP_RND_COMPAT_BITS_MIN
1057 - ARCH_MMAP_RND_COMPAT_BITS_MAX
1058
1059config ARCH_MMAP_RND_COMPAT_BITS_MIN
1060 int
1061
1062config ARCH_MMAP_RND_COMPAT_BITS_MAX
1063 int
1064
1065config ARCH_MMAP_RND_COMPAT_BITS_DEFAULT
1066 int
1067
1068config ARCH_MMAP_RND_COMPAT_BITS
1069 int "Number of bits to use for ASLR of mmap base address for compatible applications" if EXPERT
1070 range ARCH_MMAP_RND_COMPAT_BITS_MIN ARCH_MMAP_RND_COMPAT_BITS_MAX
1071 default ARCH_MMAP_RND_COMPAT_BITS_DEFAULT if ARCH_MMAP_RND_COMPAT_BITS_DEFAULT
1072 default ARCH_MMAP_RND_COMPAT_BITS_MIN
1073 depends on HAVE_ARCH_MMAP_RND_COMPAT_BITS
1074 help
1075 This value can be used to select the number of bits to use to
1076 determine the random offset to the base address of vma regions
1077 resulting from mmap allocations for compatible applications This
1078 value will be bounded by the architecture's minimum and maximum
1079 supported values.
1080
1081 This value can be changed after boot using the
1082 /proc/sys/vm/mmap_rnd_compat_bits tunable
1083
1b028f78
DS
1084config HAVE_ARCH_COMPAT_MMAP_BASES
1085 bool
1086 help
1087 This allows 64bit applications to invoke 32-bit mmap() syscall
1088 and vice-versa 32-bit applications to call 64-bit mmap().
1089 Required for applications doing different bitness syscalls.
1090
1f0e290c
GR
1091config PAGE_SIZE_LESS_THAN_64KB
1092 def_bool y
1093 depends on !ARM64_64K_PAGES
1094 depends on !IA64_PAGE_SIZE_64KB
1095 depends on !PAGE_SIZE_64KB
1096 depends on !PARISC_PAGE_SIZE_64KB
e4bbd20d
NC
1097 depends on PAGE_SIZE_LESS_THAN_256KB
1098
1099config PAGE_SIZE_LESS_THAN_256KB
1100 def_bool y
1f0e290c
GR
1101 depends on !PAGE_SIZE_256KB
1102
67f3977f
AG
1103# This allows to use a set of generic functions to determine mmap base
1104# address by giving priority to top-down scheme only if the process
1105# is not in legacy mode (compat task, unlimited stack size or
1106# sysctl_legacy_va_layout).
1107# Architecture that selects this option can provide its own version of:
1108# - STACK_RND_MASK
1109config ARCH_WANT_DEFAULT_TOPDOWN_MMAP_LAYOUT
1110 bool
1111 depends on MMU
e7142bf5 1112 select ARCH_HAS_ELF_RANDOMIZE
67f3977f 1113
03f16cd0
JP
1114config HAVE_OBJTOOL
1115 bool
1116
4ab7674f
JP
1117config HAVE_JUMP_LABEL_HACK
1118 bool
1119
22102f45
JP
1120config HAVE_NOINSTR_HACK
1121 bool
1122
489e355b
JP
1123config HAVE_NOINSTR_VALIDATION
1124 bool
1125
5f3da8c0
JP
1126config HAVE_UACCESS_VALIDATION
1127 bool
1128 select OBJTOOL
1129
b9ab5ebb
JP
1130config HAVE_STACK_VALIDATION
1131 bool
1132 help
03f16cd0
JP
1133 Architecture supports objtool compile-time frame pointer rule
1134 validation.
b9ab5ebb 1135
af085d90
JP
1136config HAVE_RELIABLE_STACKTRACE
1137 bool
1138 help
140d7e88
MB
1139 Architecture has either save_stack_trace_tsk_reliable() or
1140 arch_stack_walk_reliable() function which only returns a stack trace
1141 if it can guarantee the trace is reliable.
af085d90 1142
468a9428
GS
1143config HAVE_ARCH_HASH
1144 bool
1145 default n
1146 help
1147 If this is set, the architecture provides an <asm/hash.h>
1148 file which provides platform-specific implementations of some
1149 functions in <linux/hash.h> or fs/namei.c.
1150
666047fe
FT
1151config HAVE_ARCH_NVRAM_OPS
1152 bool
1153
3a495511
WBG
1154config ISA_BUS_API
1155 def_bool ISA
1156
d2125043
AV
1157#
1158# ABI hall of shame
1159#
1160config CLONE_BACKWARDS
1161 bool
1162 help
1163 Architecture has tls passed as the 4th argument of clone(2),
1164 not the 5th one.
1165
1166config CLONE_BACKWARDS2
1167 bool
1168 help
1169 Architecture has the first two arguments of clone(2) swapped.
1170
dfa9771a
MS
1171config CLONE_BACKWARDS3
1172 bool
1173 help
1174 Architecture has tls passed as the 3rd argument of clone(2),
1175 not the 5th one.
1176
eaca6eae
AV
1177config ODD_RT_SIGACTION
1178 bool
1179 help
1180 Architecture has unusual rt_sigaction(2) arguments
1181
0a0e8cdf
AV
1182config OLD_SIGSUSPEND
1183 bool
1184 help
1185 Architecture has old sigsuspend(2) syscall, of one-argument variety
1186
1187config OLD_SIGSUSPEND3
1188 bool
1189 help
1190 Even weirder antique ABI - three-argument sigsuspend(2)
1191
495dfbf7
AV
1192config OLD_SIGACTION
1193 bool
1194 help
1195 Architecture has old sigaction(2) syscall. Nope, not the same
1196 as OLD_SIGSUSPEND | OLD_SIGSUSPEND3 - alpha has sigsuspend(2),
1197 but fairly different variant of sigaction(2), thanks to OSF/1
1198 compatibility...
1199
1200config COMPAT_OLD_SIGACTION
1201 bool
1202
17435e5f 1203config COMPAT_32BIT_TIME
942437c9
AB
1204 bool "Provide system calls for 32-bit time_t"
1205 default !64BIT || COMPAT
17435e5f
DD
1206 help
1207 This enables 32 bit time_t support in addition to 64 bit time_t support.
1208 This is relevant on all 32-bit architectures, and 64-bit architectures
1209 as part of compat syscall handling.
1210
87a4c375
CH
1211config ARCH_NO_PREEMPT
1212 bool
1213
cb2c7d1a
MS
1214config ARCH_EPHEMERAL_INODES
1215 def_bool n
1216 help
1217 An arch should select this symbol if it doesn't keep track of inode
1218 instances on its own, but instead relies on something else (e.g. the
1219 host kernel for an UML kernel).
1220
a50a3f4b
TG
1221config ARCH_SUPPORTS_RT
1222 bool
1223
fff7fb0b
ZZ
1224config CPU_NO_EFFICIENT_FFS
1225 def_bool n
1226
ba14a194
AL
1227config HAVE_ARCH_VMAP_STACK
1228 def_bool n
1229 help
1230 An arch should select this symbol if it can support kernel stacks
1231 in vmalloc space. This means:
1232
1233 - vmalloc space must be large enough to hold many kernel stacks.
1234 This may rule out many 32-bit architectures.
1235
1236 - Stacks in vmalloc space need to work reliably. For example, if
1237 vmap page tables are created on demand, either this mechanism
1238 needs to work while the stack points to a virtual address with
1239 unpopulated page tables or arch code (switch_to() and switch_mm(),
1240 most likely) needs to ensure that the stack's page table entries
1241 are populated before running on a possibly unpopulated stack.
1242
1243 - If the stack overflows into a guard page, something reasonable
1244 should happen. The definition of "reasonable" is flexible, but
1245 instantly rebooting without logging anything would be unfriendly.
1246
1247config VMAP_STACK
1248 default y
1249 bool "Use a virtually-mapped stack"
eafb149e 1250 depends on HAVE_ARCH_VMAP_STACK
38dd767d 1251 depends on !KASAN || KASAN_HW_TAGS || KASAN_VMALLOC
a7f7f624 1252 help
ba14a194
AL
1253 Enable this if you want the use virtually-mapped kernel stacks
1254 with guard pages. This causes kernel stack overflows to be
1255 caught immediately rather than causing difficult-to-diagnose
1256 corruption.
1257
38dd767d
AK
1258 To use this with software KASAN modes, the architecture must support
1259 backing virtual mappings with real shadow memory, and KASAN_VMALLOC
1260 must be enabled.
ba14a194 1261
39218ff4
KC
1262config HAVE_ARCH_RANDOMIZE_KSTACK_OFFSET
1263 def_bool n
1264 help
1265 An arch should select this symbol if it can support kernel stack
1266 offset randomization with calls to add_random_kstack_offset()
1267 during syscall entry and choose_random_kstack_offset() during
1268 syscall exit. Careful removal of -fstack-protector-strong and
1269 -fstack-protector should also be applied to the entry code and
1270 closely examined, as the artificial stack bump looks like an array
1271 to the compiler, so it will attempt to add canary checks regardless
1272 of the static branch state.
1273
8cb37a59
ME
1274config RANDOMIZE_KSTACK_OFFSET
1275 bool "Support for randomizing kernel stack offset on syscall entry" if EXPERT
1276 default y
39218ff4 1277 depends on HAVE_ARCH_RANDOMIZE_KSTACK_OFFSET
efa90c11 1278 depends on INIT_STACK_NONE || !CC_IS_CLANG || CLANG_VERSION >= 140000
39218ff4
KC
1279 help
1280 The kernel stack offset can be randomized (after pt_regs) by
1281 roughly 5 bits of entropy, frustrating memory corruption
1282 attacks that depend on stack address determinism or
8cb37a59
ME
1283 cross-syscall address exposures.
1284
1285 The feature is controlled via the "randomize_kstack_offset=on/off"
1286 kernel boot param, and if turned off has zero overhead due to its use
1287 of static branches (see JUMP_LABEL).
1288
1289 If unsure, say Y.
1290
1291config RANDOMIZE_KSTACK_OFFSET_DEFAULT
1292 bool "Default state of kernel stack offset randomization"
1293 depends on RANDOMIZE_KSTACK_OFFSET
1294 help
1295 Kernel stack offset randomization is controlled by kernel boot param
1296 "randomize_kstack_offset=on/off", and this config chooses the default
1297 boot state.
39218ff4 1298
ad21fc4f
LA
1299config ARCH_OPTIONAL_KERNEL_RWX
1300 def_bool n
1301
1302config ARCH_OPTIONAL_KERNEL_RWX_DEFAULT
1303 def_bool n
1304
1305config ARCH_HAS_STRICT_KERNEL_RWX
1306 def_bool n
1307
0f5bf6d0 1308config STRICT_KERNEL_RWX
ad21fc4f
LA
1309 bool "Make kernel text and rodata read-only" if ARCH_OPTIONAL_KERNEL_RWX
1310 depends on ARCH_HAS_STRICT_KERNEL_RWX
1311 default !ARCH_OPTIONAL_KERNEL_RWX || ARCH_OPTIONAL_KERNEL_RWX_DEFAULT
1312 help
1313 If this is set, kernel text and rodata memory will be made read-only,
1314 and non-text memory will be made non-executable. This provides
1315 protection against certain security exploits (e.g. executing the heap
1316 or modifying text)
1317
1318 These features are considered standard security practice these days.
1319 You should say Y here in almost all cases.
1320
1321config ARCH_HAS_STRICT_MODULE_RWX
1322 def_bool n
1323
0f5bf6d0 1324config STRICT_MODULE_RWX
ad21fc4f
LA
1325 bool "Set loadable kernel module data as NX and text as RO" if ARCH_OPTIONAL_KERNEL_RWX
1326 depends on ARCH_HAS_STRICT_MODULE_RWX && MODULES
1327 default !ARCH_OPTIONAL_KERNEL_RWX || ARCH_OPTIONAL_KERNEL_RWX_DEFAULT
1328 help
1329 If this is set, module text and rodata memory will be made read-only,
1330 and non-text memory will be made non-executable. This provides
1331 protection against certain security exploits (e.g. writing to text)
1332
ea8c64ac
CH
1333# select if the architecture provides an asm/dma-direct.h header
1334config ARCH_HAS_PHYS_TO_DMA
1335 bool
1336
04f264d3
PB
1337config HAVE_ARCH_COMPILER_H
1338 bool
1339 help
1340 An architecture can select this if it provides an
1341 asm/compiler.h header that should be included after
1342 linux/compiler-*.h in order to override macro definitions that those
1343 headers generally provide.
1344
271ca788
AB
1345config HAVE_ARCH_PREL32_RELOCATIONS
1346 bool
1347 help
1348 May be selected by an architecture if it supports place-relative
1349 32-bit relocations, both in the toolchain and in the module loader,
1350 in which case relative references can be used in special sections
1351 for PCI fixup, initcalls etc which are only half the size on 64 bit
1352 architectures, and don't require runtime relocation on relocatable
1353 kernels.
1354
ce9084ba
AB
1355config ARCH_USE_MEMREMAP_PROT
1356 bool
1357
fb346fd9
WL
1358config LOCK_EVENT_COUNTS
1359 bool "Locking event counts collection"
1360 depends on DEBUG_FS
a7f7f624 1361 help
fb346fd9
WL
1362 Enable light-weight counting of various locking related events
1363 in the system with minimal performance impact. This reduces
1364 the chance of application behavior change because of timing
1365 differences. The counts are reported via debugfs.
1366
5cf896fb
PC
1367# Select if the architecture has support for applying RELR relocations.
1368config ARCH_HAS_RELR
1369 bool
1370
1371config RELR
1372 bool "Use RELR relocation packing"
1373 depends on ARCH_HAS_RELR && TOOLS_SUPPORT_RELR
1374 default y
1375 help
1376 Store the kernel's dynamic relocations in the RELR relocation packing
1377 format. Requires a compatible linker (LLD supports this feature), as
1378 well as compatible NM and OBJCOPY utilities (llvm-nm and llvm-objcopy
1379 are compatible).
1380
0c9c1d56
TJB
1381config ARCH_HAS_MEM_ENCRYPT
1382 bool
1383
46b49b12
TL
1384config ARCH_HAS_CC_PLATFORM
1385 bool
1386
0e242208 1387config HAVE_SPARSE_SYSCALL_NR
9f79ffc1
JH
1388 bool
1389 help
1390 An architecture should select this if its syscall numbering is sparse
0e242208
HN
1391 to save space. For example, MIPS architecture has a syscall array with
1392 entries at 4000, 5000 and 6000 locations. This option turns on syscall
1393 related optimizations for a given architecture.
1394
d60d7de3
SS
1395config ARCH_HAS_VDSO_DATA
1396 bool
1397
115284d8
JP
1398config HAVE_STATIC_CALL
1399 bool
1400
9183c3f9
JP
1401config HAVE_STATIC_CALL_INLINE
1402 bool
1403 depends on HAVE_STATIC_CALL
03f16cd0 1404 select OBJTOOL
9183c3f9 1405
6ef869e0
MH
1406config HAVE_PREEMPT_DYNAMIC
1407 bool
99cf983c
MR
1408
1409config HAVE_PREEMPT_DYNAMIC_CALL
1410 bool
6ef869e0 1411 depends on HAVE_STATIC_CALL
99cf983c
MR
1412 select HAVE_PREEMPT_DYNAMIC
1413 help
9f79ffc1
JH
1414 An architecture should select this if it can handle the preemption
1415 model being selected at boot time using static calls.
99cf983c 1416
9f79ffc1
JH
1417 Where an architecture selects HAVE_STATIC_CALL_INLINE, any call to a
1418 preemption function will be patched directly.
99cf983c 1419
9f79ffc1
JH
1420 Where an architecture does not select HAVE_STATIC_CALL_INLINE, any
1421 call to a preemption function will go through a trampoline, and the
1422 trampoline will be patched.
99cf983c 1423
9f79ffc1
JH
1424 It is strongly advised to support inline static call to avoid any
1425 overhead.
99cf983c
MR
1426
1427config HAVE_PREEMPT_DYNAMIC_KEY
1428 bool
a0a12c3e 1429 depends on HAVE_ARCH_JUMP_LABEL
99cf983c 1430 select HAVE_PREEMPT_DYNAMIC
6ef869e0 1431 help
9f79ffc1
JH
1432 An architecture should select this if it can handle the preemption
1433 model being selected at boot time using static keys.
99cf983c 1434
9f79ffc1
JH
1435 Each preemption function will be given an early return based on a
1436 static key. This should have slightly lower overhead than non-inline
1437 static calls, as this effectively inlines each trampoline into the
1438 start of its callee. This may avoid redundant work, and may
1439 integrate better with CFI schemes.
99cf983c 1440
9f79ffc1
JH
1441 This will have greater overhead than using inline static calls as
1442 the call to the preemption function cannot be entirely elided.
6ef869e0 1443
59612b24
NC
1444config ARCH_WANT_LD_ORPHAN_WARN
1445 bool
1446 help
1447 An arch should select this symbol once all linker sections are explicitly
1448 included, size-asserted, or discarded in the linker scripts. This is
1449 important because we never want expected sections to be placed heuristically
1450 by the linker, since the locations of such sections can change between linker
1451 versions.
1452
4f5b0c17
MR
1453config HAVE_ARCH_PFN_VALID
1454 bool
1455
5d6ad668
MR
1456config ARCH_SUPPORTS_DEBUG_PAGEALLOC
1457 bool
1458
df4e817b
PT
1459config ARCH_SUPPORTS_PAGE_TABLE_CHECK
1460 bool
1461
2ca408d9
BG
1462config ARCH_SPLIT_ARG64
1463 bool
1464 help
9f79ffc1
JH
1465 If a 32-bit architecture requires 64-bit arguments to be split into
1466 pairs of 32-bit arguments, select this option.
2ca408d9 1467
7facdc42
AV
1468config ARCH_HAS_ELFCORE_COMPAT
1469 bool
1470
58e106e7
BS
1471config ARCH_HAS_PARANOID_L1D_FLUSH
1472 bool
1473
d593d64f
PS
1474config ARCH_HAVE_TRACE_MMIO_ACCESS
1475 bool
1476
1bdda24c
TG
1477config DYNAMIC_SIGFRAME
1478 bool
1479
50468e43
JS
1480# Select, if arch has a named attribute group bound to NUMA device nodes.
1481config HAVE_ARCH_NODE_DEV_GROUP
1482 bool
1483
eed9a328
YZ
1484config ARCH_HAS_NONLEAF_PMD_YOUNG
1485 bool
1486 help
1487 Architectures that select this option are capable of setting the
1488 accessed bit in non-leaf PMD entries when using them as part of linear
1489 address translations. Page table walkers that clear the accessed bit
1490 may use this capability to reduce their search space.
1491
2521f2c2 1492source "kernel/gcov/Kconfig"
45332b1b
MY
1493
1494source "scripts/gcc-plugins/Kconfig"
fa1b5d09 1495
d49a0626
PZ
1496config FUNCTION_ALIGNMENT_4B
1497 bool
1498
1499config FUNCTION_ALIGNMENT_8B
1500 bool
1501
1502config FUNCTION_ALIGNMENT_16B
1503 bool
1504
1505config FUNCTION_ALIGNMENT_32B
1506 bool
1507
1508config FUNCTION_ALIGNMENT_64B
1509 bool
1510
1511config FUNCTION_ALIGNMENT
1512 int
1513 default 64 if FUNCTION_ALIGNMENT_64B
1514 default 32 if FUNCTION_ALIGNMENT_32B
1515 default 16 if FUNCTION_ALIGNMENT_16B
1516 default 8 if FUNCTION_ALIGNMENT_8B
1517 default 4 if FUNCTION_ALIGNMENT_4B
1518 default 0
1519
22471e13 1520endmenu
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