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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
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RD
12menu "General architecture-dependent options"
13
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14config ARCH_HAS_SUBPAGE_FAULTS
15 bool
16 help
17 Select if the architecture can check permissions at sub-page
18 granularity (e.g. arm64 MTE). The probe_user_*() functions
19 must be implemented.
20
05736e4a
TG
21config HOTPLUG_SMT
22 bool
23
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ME
24config SMT_NUM_THREADS_DYNAMIC
25 bool
26
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TG
27# Selected by HOTPLUG_CORE_SYNC_DEAD or HOTPLUG_CORE_SYNC_FULL
28config HOTPLUG_CORE_SYNC
29 bool
30
31# Basic CPU dead synchronization selected by architecture
32config HOTPLUG_CORE_SYNC_DEAD
33 bool
34 select HOTPLUG_CORE_SYNC
35
36# Full CPU synchronization with alive state selected by architecture
37config HOTPLUG_CORE_SYNC_FULL
38 bool
39 select HOTPLUG_CORE_SYNC_DEAD if HOTPLUG_CPU
40 select HOTPLUG_CORE_SYNC
41
a631be92
TG
42config HOTPLUG_SPLIT_STARTUP
43 bool
44 select HOTPLUG_CORE_SYNC_FULL
45
18415f33
TG
46config HOTPLUG_PARALLEL
47 bool
48 select HOTPLUG_SPLIT_STARTUP
49
142781e1 50config GENERIC_ENTRY
9f79ffc1 51 bool
142781e1 52
125e5645
MD
53config KPROBES
54 bool "Kprobes"
05ed160e 55 depends on MODULES
125e5645 56 depends on HAVE_KPROBES
05ed160e 57 select KALLSYMS
835f14ed 58 select TASKS_RCU if PREEMPTION
125e5645
MD
59 help
60 Kprobes allows you to trap at almost any kernel address and
61 execute a callback function. register_kprobe() establishes
62 a probepoint and specifies the callback. Kprobes is useful
63 for kernel debugging, non-intrusive instrumentation and testing.
64 If in doubt, say "N".
65
45f81b1c 66config JUMP_LABEL
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KK
67 bool "Optimize very unlikely/likely branches"
68 depends on HAVE_ARCH_JUMP_LABEL
4ab7674f 69 select OBJTOOL if HAVE_JUMP_LABEL_HACK
24b54fee 70 help
9f79ffc1
JH
71 This option enables a transparent branch optimization that
72 makes certain almost-always-true or almost-always-false branch
73 conditions even cheaper to execute within the kernel.
c5905afb 74
9f79ffc1
JH
75 Certain performance-sensitive kernel code, such as trace points,
76 scheduler functionality, networking code and KVM have such
77 branches and include support for this optimization technique.
c5905afb 78
9f79ffc1
JH
79 If it is detected that the compiler has support for "asm goto",
80 the kernel will compile such branches with just a nop
81 instruction. When the condition flag is toggled to true, the
82 nop will be converted to a jump instruction to execute the
83 conditional block of instructions.
c5905afb 84
9f79ffc1
JH
85 This technique lowers overhead and stress on the branch prediction
86 of the processor and generally makes the kernel faster. The update
87 of the condition is slower, but those are always very rare.
45f81b1c 88
9f79ffc1
JH
89 ( On 32-bit x86, the necessary options added to the compiler
90 flags may increase the size of the kernel slightly. )
45f81b1c 91
1987c947
PZ
92config STATIC_KEYS_SELFTEST
93 bool "Static key selftest"
94 depends on JUMP_LABEL
95 help
96 Boot time self-test of the branch patching code.
97
f03c4129
PZ
98config STATIC_CALL_SELFTEST
99 bool "Static call selftest"
100 depends on HAVE_STATIC_CALL
101 help
102 Boot time self-test of the call patching code.
103
afd66255 104config OPTPROBES
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MH
105 def_bool y
106 depends on KPROBES && HAVE_OPTPROBES
01b1d88b 107 select TASKS_RCU if PREEMPTION
afd66255 108
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MH
109config KPROBES_ON_FTRACE
110 def_bool y
111 depends on KPROBES && HAVE_KPROBES_ON_FTRACE
112 depends on DYNAMIC_FTRACE_WITH_REGS
113 help
9f79ffc1
JH
114 If function tracer is enabled and the arch supports full
115 passing of pt_regs to function tracing, then kprobes can
116 optimize on top of function tracing.
e7dbfe34 117
2b144498 118config UPROBES
09294e31 119 def_bool n
e8f4aa60 120 depends on ARCH_SUPPORTS_UPROBES
2b144498 121 help
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IM
122 Uprobes is the user-space counterpart to kprobes: they
123 enable instrumentation applications (such as 'perf probe')
124 to establish unintrusive probes in user-space binaries and
125 libraries, by executing handler functions when the probes
126 are hit by user-space applications.
127
128 ( These probes come in the form of single-byte breakpoints,
129 managed by the kernel and kept transparent to the probed
130 application. )
2b144498 131
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SRV
132config HAVE_64BIT_ALIGNED_ACCESS
133 def_bool 64BIT && !HAVE_EFFICIENT_UNALIGNED_ACCESS
134 help
135 Some architectures require 64 bit accesses to be 64 bit
136 aligned, which also requires structs containing 64 bit values
137 to be 64 bit aligned too. This includes some 32 bit
138 architectures which can do 64 bit accesses, as well as 64 bit
139 architectures without unaligned access.
140
141 This symbol should be selected by an architecture if 64 bit
142 accesses are required to be 64 bit aligned in this way even
143 though it is not a 64 bit architecture.
144
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LB
145 See Documentation/core-api/unaligned-memory-access.rst for
146 more information on the topic of unaligned memory accesses.
adab66b7 147
58340a07 148config HAVE_EFFICIENT_UNALIGNED_ACCESS
9ba16087 149 bool
58340a07
JB
150 help
151 Some architectures are unable to perform unaligned accesses
152 without the use of get_unaligned/put_unaligned. Others are
153 unable to perform such accesses efficiently (e.g. trap on
154 unaligned access and require fixing it up in the exception
155 handler.)
156
157 This symbol should be selected by an architecture if it can
158 perform unaligned accesses efficiently to allow different
159 code paths to be selected for these cases. Some network
160 drivers, for example, could opt to not fix up alignment
161 problems with received packets if doing so would not help
162 much.
163
c9b54d6f 164 See Documentation/core-api/unaligned-memory-access.rst for more
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165 information on the topic of unaligned memory accesses.
166
cf66bb93 167config ARCH_USE_BUILTIN_BSWAP
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168 bool
169 help
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JH
170 Modern versions of GCC (since 4.4) have builtin functions
171 for handling byte-swapping. Using these, instead of the old
172 inline assembler that the architecture code provides in the
173 __arch_bswapXX() macros, allows the compiler to see what's
174 happening and offers more opportunity for optimisation. In
175 particular, the compiler will be able to combine the byteswap
176 with a nearby load or store and use load-and-swap or
177 store-and-swap instructions if the architecture has them. It
178 should almost *never* result in code which is worse than the
179 hand-coded assembler in <asm/swab.h>. But just in case it
180 does, the use of the builtins is optional.
cf66bb93 181
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JH
182 Any architecture with load-and-swap or store-and-swap
183 instructions should set this. And it shouldn't hurt to set it
184 on architectures that don't have such instructions.
cf66bb93 185
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AM
186config KRETPROBES
187 def_bool y
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188 depends on KPROBES && (HAVE_KRETPROBES || HAVE_RETHOOK)
189
190config KRETPROBE_ON_RETHOOK
191 def_bool y
192 depends on HAVE_RETHOOK
193 depends on KRETPROBES
194 select RETHOOK
9edddaa2 195
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196config USER_RETURN_NOTIFIER
197 bool
198 depends on HAVE_USER_RETURN_NOTIFIER
199 help
200 Provide a kernel-internal notification when a cpu is about to
201 switch to user mode.
202
28b2ee20 203config HAVE_IOREMAP_PROT
9ba16087 204 bool
28b2ee20 205
125e5645 206config HAVE_KPROBES
9ba16087 207 bool
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AM
208
209config HAVE_KRETPROBES
9ba16087 210 bool
74bc7cee 211
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212config HAVE_OPTPROBES
213 bool
d314d74c 214
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215config HAVE_KPROBES_ON_FTRACE
216 bool
217
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218config ARCH_CORRECT_STACKTRACE_ON_KRETPROBE
219 bool
220 help
221 Since kretprobes modifies return address on the stack, the
222 stacktrace may see the kretprobe trampoline address instead
223 of correct one. If the architecture stacktrace code and
224 unwinder can adjust such entries, select this configuration.
225
540adea3 226config HAVE_FUNCTION_ERROR_INJECTION
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227 bool
228
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229config HAVE_NMI
230 bool
231
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232config HAVE_FUNCTION_DESCRIPTORS
233 bool
234
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MY
235config TRACE_IRQFLAGS_SUPPORT
236 bool
237
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238config TRACE_IRQFLAGS_NMI_SUPPORT
239 bool
240
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RM
241#
242# An arch should select this if it provides all these things:
243#
244# task_pt_regs() in asm/processor.h or asm/ptrace.h
245# arch_has_single_step() if there is hardware single-step support
246# arch_has_block_step() if there is hardware block-step support
1f5a4ad9
RM
247# asm/syscall.h supplying asm-generic/syscall.h interface
248# linux/regset.h user_regset interfaces
249# CORE_DUMP_USE_REGSET #define'd in linux/elf.h
153474ba 250# TIF_SYSCALL_TRACE calls ptrace_report_syscall_{entry,exit}
03248add 251# TIF_NOTIFY_RESUME calls resume_user_mode_work()
1f5a4ad9
RM
252#
253config HAVE_ARCH_TRACEHOOK
9ba16087 254 bool
1f5a4ad9 255
c64be2bb
MS
256config HAVE_DMA_CONTIGUOUS
257 bool
258
29d5e047 259config GENERIC_SMP_IDLE_THREAD
24b54fee 260 bool
29d5e047 261
485cf5da 262config GENERIC_IDLE_POLL_SETUP
24b54fee 263 bool
485cf5da 264
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265config ARCH_HAS_FORTIFY_SOURCE
266 bool
267 help
268 An architecture should select this when it can successfully
269 build and run with CONFIG_FORTIFY_SOURCE.
270
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271#
272# Select if the arch provides a historic keepinit alias for the retain_initrd
273# command line option
274#
275config ARCH_HAS_KEEPINITRD
276 bool
277
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278# Select if arch has all set_memory_ro/rw/x/nx() functions in asm/cacheflush.h
279config ARCH_HAS_SET_MEMORY
280 bool
281
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RE
282# Select if arch has all set_direct_map_invalid/default() functions
283config ARCH_HAS_SET_DIRECT_MAP
284 bool
285
c30700db 286#
fa7e2247 287# Select if the architecture provides the arch_dma_set_uncached symbol to
a86ecfa6 288# either provide an uncached segment alias for a DMA allocation, or
fa7e2247 289# to remap the page tables in place.
c30700db 290#
fa7e2247 291config ARCH_HAS_DMA_SET_UNCACHED
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292 bool
293
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CH
294#
295# Select if the architectures provides the arch_dma_clear_uncached symbol
296# to undo an in-place page table remap for uncached access.
297#
298config ARCH_HAS_DMA_CLEAR_UNCACHED
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CH
299 bool
300
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TG
301config ARCH_HAS_CPU_FINALIZE_INIT
302 bool
303
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JG
304# The architecture has a per-task state that includes the mm's PASID
305config ARCH_HAS_CPU_PASID
306 bool
307 select IOMMU_MM_DATA
308
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KC
309config HAVE_ARCH_THREAD_STRUCT_WHITELIST
310 bool
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KC
311 help
312 An architecture should select this to provide hardened usercopy
313 knowledge about what region of the thread_struct should be
314 whitelisted for copying to userspace. Normally this is only the
315 FPU registers. Specifically, arch_thread_struct_whitelist()
316 should be implemented. Without this, the entire thread_struct
317 field in task_struct will be left whitelisted.
318
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IM
319# Select if arch wants to size task_struct dynamically via arch_task_struct_size:
320config ARCH_WANTS_DYNAMIC_TASK_STRUCT
321 bool
322
51c2ee6d
ND
323config ARCH_WANTS_NO_INSTR
324 bool
325 help
326 An architecture should select this if the noinstr macro is being used on
327 functions to denote that the toolchain should avoid instrumenting such
328 functions and is required for correctness.
329
942fa985
YN
330config ARCH_32BIT_OFF_T
331 bool
332 depends on !64BIT
333 help
334 All new 32-bit architectures should have 64-bit off_t type on
335 userspace side which corresponds to the loff_t kernel type. This
336 is the requirement for modern ABIs. Some existing architectures
337 still support 32-bit off_t. This option is enabled for all such
338 architectures explicitly.
339
96c0a6a7
HC
340# Selected by 64 bit architectures which have a 32 bit f_tinode in struct ustat
341config ARCH_32BIT_USTAT_F_TINODE
342 bool
343
2ff2b7ec
MY
344config HAVE_ASM_MODVERSIONS
345 bool
346 help
a86ecfa6 347 This symbol should be selected by an architecture if it provides
2ff2b7ec
MY
348 <asm/asm-prototypes.h> to support the module versioning for symbols
349 exported from assembly code.
350
f850c30c
HC
351config HAVE_REGS_AND_STACK_ACCESS_API
352 bool
e01292b1 353 help
a86ecfa6 354 This symbol should be selected by an architecture if it supports
e01292b1
HC
355 the API needed to access registers and stack entries from pt_regs,
356 declared in asm/ptrace.h
357 For example the kprobes-based event tracer needs this API.
f850c30c 358
d7822b1e
MD
359config HAVE_RSEQ
360 bool
361 depends on HAVE_REGS_AND_STACK_ACCESS_API
362 help
363 This symbol should be selected by an architecture if it
364 supports an implementation of restartable sequences.
365
2f7ab126
MO
366config HAVE_RUST
367 bool
368 help
369 This symbol should be selected by an architecture if it
370 supports Rust.
371
3c88ee19
MH
372config HAVE_FUNCTION_ARG_ACCESS_API
373 bool
374 help
a86ecfa6 375 This symbol should be selected by an architecture if it supports
3c88ee19
MH
376 the API needed to access function arguments from pt_regs,
377 declared in asm/ptrace.h
378
62a038d3
P
379config HAVE_HW_BREAKPOINT
380 bool
99e8c5a3 381 depends on PERF_EVENTS
62a038d3 382
0102752e
FW
383config HAVE_MIXED_BREAKPOINTS_REGS
384 bool
385 depends on HAVE_HW_BREAKPOINT
386 help
387 Depending on the arch implementation of hardware breakpoints,
388 some of them have separate registers for data and instruction
389 breakpoints addresses, others have mixed registers to store
390 them but define the access type in a control register.
391 Select this option if your arch implements breakpoints under the
392 latter fashion.
393
7c68af6e
AK
394config HAVE_USER_RETURN_NOTIFIER
395 bool
a1922ed6 396
c01d4323
FW
397config HAVE_PERF_EVENTS_NMI
398 bool
23637d47
FW
399 help
400 System hardware can generate an NMI using the perf event
401 subsystem. Also has support for calculating CPU cycle events
402 to determine how many clock cycles in a given period.
c01d4323 403
05a4a952
NP
404config HAVE_HARDLOCKUP_DETECTOR_PERF
405 bool
406 depends on HAVE_PERF_EVENTS_NMI
407 help
408 The arch chooses to use the generic perf-NMI-based hardlockup
409 detector. Must define HAVE_PERF_EVENTS_NMI.
410
05a4a952
NP
411config HAVE_HARDLOCKUP_DETECTOR_ARCH
412 bool
05a4a952 413 help
1356d0b9
PM
414 The arch provides its own hardlockup detector implementation instead
415 of the generic ones.
416
417 It uses the same command line parameters, and sysctl interface,
418 as the generic hardlockup detectors.
05a4a952 419
c5e63197
JO
420config HAVE_PERF_REGS
421 bool
422 help
423 Support selective register dumps for perf events. This includes
424 bit-mapping of each registers and a unique architecture id.
425
c5ebcedb
JO
426config HAVE_PERF_USER_STACK_DUMP
427 bool
428 help
429 Support user stack dumps for perf event samples. This needs
430 access to the user stack pointer which is not unified across
431 architectures.
432
bf5438fc
JB
433config HAVE_ARCH_JUMP_LABEL
434 bool
435
50ff18ab
AB
436config HAVE_ARCH_JUMP_LABEL_RELATIVE
437 bool
438
0d6e24d4
PZ
439config MMU_GATHER_TABLE_FREE
440 bool
441
ff2e6d72 442config MMU_GATHER_RCU_TABLE_FREE
26723911 443 bool
0d6e24d4 444 select MMU_GATHER_TABLE_FREE
26723911 445
3af4bd03 446config MMU_GATHER_PAGE_SIZE
ed6a7935
PZ
447 bool
448
27796d03
PZ
449config MMU_GATHER_NO_RANGE
450 bool
1e9fdf21
PZ
451 select MMU_GATHER_MERGE_VMAS
452
453config MMU_GATHER_NO_FLUSH_CACHE
454 bool
455
456config MMU_GATHER_MERGE_VMAS
457 bool
27796d03 458
580a586c 459config MMU_GATHER_NO_GATHER
952a31c9 460 bool
0d6e24d4 461 depends on MMU_GATHER_TABLE_FREE
952a31c9 462
d53c3dfb
NP
463config ARCH_WANT_IRQS_OFF_ACTIVATE_MM
464 bool
465 help
466 Temporary select until all architectures can be converted to have
467 irqs disabled over activate_mm. Architectures that do IPI based TLB
468 shootdowns should enable this.
469
88e3009b
NP
470# Use normal mm refcounting for MMU_LAZY_TLB kernel thread references.
471# MMU_LAZY_TLB_REFCOUNT=n can improve the scalability of context switching
472# to/from kernel threads when the same mm is running on a lot of CPUs (a large
473# multi-threaded application), by reducing contention on the mm refcount.
474#
475# This can be disabled if the architecture ensures no CPUs are using an mm as a
476# "lazy tlb" beyond its final refcount (i.e., by the time __mmdrop frees the mm
477# or its kernel page tables). This could be arranged by arch_exit_mmap(), or
478# final exit(2) TLB flush, for example.
479#
480# To implement this, an arch *must*:
481# Ensure the _lazy_tlb variants of mmgrab/mmdrop are used when manipulating
482# the lazy tlb reference of a kthread's ->active_mm (non-arch code has been
483# converted already).
484config MMU_LAZY_TLB_REFCOUNT
485 def_bool y
2655421a
NP
486 depends on !MMU_LAZY_TLB_SHOOTDOWN
487
488# This option allows MMU_LAZY_TLB_REFCOUNT=n. It ensures no CPUs are using an
489# mm as a lazy tlb beyond its last reference count, by shooting down these
490# users before the mm is deallocated. __mmdrop() first IPIs all CPUs that may
491# be using the mm as a lazy tlb, so that they may switch themselves to using
492# init_mm for their active mm. mm_cpumask(mm) is used to determine which CPUs
493# may be using mm as a lazy tlb mm.
494#
495# To implement this, an arch *must*:
496# - At the time of the final mmdrop of the mm, ensure mm_cpumask(mm) contains
497# at least all possible CPUs in which the mm is lazy.
498# - It must meet the requirements for MMU_LAZY_TLB_REFCOUNT=n (see above).
499config MMU_LAZY_TLB_SHOOTDOWN
500 bool
88e3009b 501
df013ffb
HY
502config ARCH_HAVE_NMI_SAFE_CMPXCHG
503 bool
504
2e83b879
PM
505config ARCH_HAS_NMI_SAFE_THIS_CPU_OPS
506 bool
507
43570fd2
HC
508config HAVE_ALIGNED_STRUCT_PAGE
509 bool
510 help
511 This makes sure that struct pages are double word aligned and that
512 e.g. the SLUB allocator can perform double word atomic operations
513 on a struct page for better performance. However selecting this
514 might increase the size of a struct page by a word.
515
4156153c
HC
516config HAVE_CMPXCHG_LOCAL
517 bool
518
2565409f
HC
519config HAVE_CMPXCHG_DOUBLE
520 bool
521
77e58496
PM
522config ARCH_WEAK_RELEASE_ACQUIRE
523 bool
524
c1d7e01d
WD
525config ARCH_WANT_IPC_PARSE_VERSION
526 bool
527
528config ARCH_WANT_COMPAT_IPC_PARSE_VERSION
529 bool
530
48b25c43 531config ARCH_WANT_OLD_COMPAT_IPC
c1d7e01d 532 select ARCH_WANT_COMPAT_IPC_PARSE_VERSION
48b25c43
CM
533 bool
534
282a181b
YZ
535config HAVE_ARCH_SECCOMP
536 bool
537 help
538 An arch should select this symbol to support seccomp mode 1 (the fixed
539 syscall policy), and must provide an overrides for __NR_seccomp_sigreturn,
540 and compat syscalls if the asm-generic/seccomp.h defaults need adjustment:
541 - __NR_seccomp_read_32
542 - __NR_seccomp_write_32
543 - __NR_seccomp_exit_32
544 - __NR_seccomp_sigreturn_32
545
e2cfabdf
WD
546config HAVE_ARCH_SECCOMP_FILTER
547 bool
282a181b 548 select HAVE_ARCH_SECCOMP
e2cfabdf 549 help
fb0fadf9 550 An arch should select this symbol if it provides all of these things:
282a181b 551 - all the requirements for HAVE_ARCH_SECCOMP
bb6ea430
WD
552 - syscall_get_arch()
553 - syscall_get_arguments()
554 - syscall_rollback()
555 - syscall_set_return_value()
fb0fadf9
WD
556 - SIGSYS siginfo_t support
557 - secure_computing is called from a ptrace_event()-safe context
558 - secure_computing return value is checked and a return value of -1
559 results in the system call being skipped immediately.
48dc92b9 560 - seccomp syscall wired up
0d8315dd
YZ
561 - if !HAVE_SPARSE_SYSCALL_NR, have SECCOMP_ARCH_NATIVE,
562 SECCOMP_ARCH_NATIVE_NR, SECCOMP_ARCH_NATIVE_NAME defined. If
563 COMPAT is supported, have the SECCOMP_ARCH_COMPAT* defines too.
e2cfabdf 564
282a181b
YZ
565config SECCOMP
566 prompt "Enable seccomp to safely execute untrusted bytecode"
567 def_bool y
568 depends on HAVE_ARCH_SECCOMP
569 help
570 This kernel feature is useful for number crunching applications
571 that may need to handle untrusted bytecode during their
572 execution. By using pipes or other transports made available
573 to the process as file descriptors supporting the read/write
574 syscalls, it's possible to isolate those applications in their
575 own address space using seccomp. Once seccomp is enabled via
576 prctl(PR_SET_SECCOMP) or the seccomp() syscall, it cannot be
577 disabled and the task is only allowed to execute a few safe
578 syscalls defined by each seccomp mode.
579
580 If unsure, say Y.
581
e2cfabdf
WD
582config SECCOMP_FILTER
583 def_bool y
584 depends on HAVE_ARCH_SECCOMP_FILTER && SECCOMP && NET
585 help
586 Enable tasks to build secure computing environments defined
587 in terms of Berkeley Packet Filter programs which implement
588 task-defined system call filtering polices.
589
5fb94e9c 590 See Documentation/userspace-api/seccomp_filter.rst for details.
e2cfabdf 591
0d8315dd
YZ
592config SECCOMP_CACHE_DEBUG
593 bool "Show seccomp filter cache status in /proc/pid/seccomp_cache"
594 depends on SECCOMP_FILTER && !HAVE_SPARSE_SYSCALL_NR
595 depends on PROC_FS
596 help
597 This enables the /proc/pid/seccomp_cache interface to monitor
598 seccomp cache data. The file format is subject to change. Reading
599 the file requires CAP_SYS_ADMIN.
600
601 This option is for debugging only. Enabling presents the risk that
602 an adversary may be able to infer the seccomp filter logic.
603
604 If unsure, say N.
605
afaef01c
AP
606config HAVE_ARCH_STACKLEAK
607 bool
608 help
609 An architecture should select this if it has the code which
610 fills the used part of the kernel stack with the STACKLEAK_POISON
611 value before returning from system calls.
612
d148eac0 613config HAVE_STACKPROTECTOR
19952a92
KC
614 bool
615 help
616 An arch should select this symbol if:
19952a92
KC
617 - it has implemented a stack canary (e.g. __stack_chk_guard)
618
050e9baa 619config STACKPROTECTOR
2a61f474 620 bool "Stack Protector buffer overflow detection"
d148eac0 621 depends on HAVE_STACKPROTECTOR
2a61f474
MY
622 depends on $(cc-option,-fstack-protector)
623 default y
19952a92 624 help
8779657d 625 This option turns on the "stack-protector" GCC feature. This
19952a92
KC
626 feature puts, at the beginning of functions, a canary value on
627 the stack just before the return address, and validates
628 the value just before actually returning. Stack based buffer
629 overflows (that need to overwrite this return address) now also
630 overwrite the canary, which gets detected and the attack is then
631 neutralized via a kernel panic.
632
8779657d
KC
633 Functions will have the stack-protector canary logic added if they
634 have an 8-byte or larger character array on the stack.
635
19952a92 636 This feature requires gcc version 4.2 or above, or a distribution
8779657d
KC
637 gcc with the feature backported ("-fstack-protector").
638
639 On an x86 "defconfig" build, this feature adds canary checks to
640 about 3% of all kernel functions, which increases kernel code size
641 by about 0.3%.
642
050e9baa 643config STACKPROTECTOR_STRONG
2a61f474 644 bool "Strong Stack Protector"
050e9baa 645 depends on STACKPROTECTOR
2a61f474
MY
646 depends on $(cc-option,-fstack-protector-strong)
647 default y
8779657d
KC
648 help
649 Functions will have the stack-protector canary logic added in any
650 of the following conditions:
651
652 - local variable's address used as part of the right hand side of an
653 assignment or function argument
654 - local variable is an array (or union containing an array),
655 regardless of array type or length
656 - uses register local variables
657
658 This feature requires gcc version 4.9 or above, or a distribution
659 gcc with the feature backported ("-fstack-protector-strong").
660
661 On an x86 "defconfig" build, this feature adds canary checks to
662 about 20% of all kernel functions, which increases the kernel code
663 size by about 2%.
664
d08b9f0c
ST
665config ARCH_SUPPORTS_SHADOW_CALL_STACK
666 bool
667 help
afcf5441
DL
668 An architecture should select this if it supports the compiler's
669 Shadow Call Stack and implements runtime support for shadow stack
aa7a65ae 670 switching.
d08b9f0c
ST
671
672config SHADOW_CALL_STACK
afcf5441
DL
673 bool "Shadow Call Stack"
674 depends on ARCH_SUPPORTS_SHADOW_CALL_STACK
38792972 675 depends on DYNAMIC_FTRACE_WITH_ARGS || DYNAMIC_FTRACE_WITH_REGS || !FUNCTION_GRAPH_TRACER
6f9dc684 676 depends on MMU
d08b9f0c 677 help
afcf5441
DL
678 This option enables the compiler's Shadow Call Stack, which
679 uses a shadow stack to protect function return addresses from
680 being overwritten by an attacker. More information can be found
681 in the compiler's documentation:
d08b9f0c 682
afcf5441
DL
683 - Clang: https://clang.llvm.org/docs/ShadowCallStack.html
684 - GCC: https://gcc.gnu.org/onlinedocs/gcc/Instrumentation-Options.html#Instrumentation-Options
d08b9f0c
ST
685
686 Note that security guarantees in the kernel differ from the
687 ones documented for user space. The kernel must store addresses
688 of shadow stacks in memory, which means an attacker capable of
689 reading and writing arbitrary memory may be able to locate them
690 and hijack control flow by modifying the stacks.
691
9beccca0
AB
692config DYNAMIC_SCS
693 bool
694 help
695 Set by the arch code if it relies on code patching to insert the
696 shadow call stack push and pop instructions rather than on the
697 compiler.
698
dc5723b0
ST
699config LTO
700 bool
701 help
702 Selected if the kernel will be built using the compiler's LTO feature.
703
704config LTO_CLANG
705 bool
706 select LTO
707 help
708 Selected if the kernel will be built using Clang's LTO feature.
709
710config ARCH_SUPPORTS_LTO_CLANG
711 bool
712 help
713 An architecture should select this option if it supports:
714 - compiling with Clang,
715 - compiling inline assembly with Clang's integrated assembler,
716 - and linking with LLD.
717
718config ARCH_SUPPORTS_LTO_CLANG_THIN
719 bool
720 help
721 An architecture should select this option if it can support Clang's
722 ThinLTO mode.
723
724config HAS_LTO_CLANG
725 def_bool y
1e68a8af 726 depends on CC_IS_CLANG && LD_IS_LLD && AS_IS_LLVM
dc5723b0
ST
727 depends on $(success,$(NM) --help | head -n 1 | grep -qi llvm)
728 depends on $(success,$(AR) --help | head -n 1 | grep -qi llvm)
729 depends on ARCH_SUPPORTS_LTO_CLANG
730 depends on !FTRACE_MCOUNT_USE_RECORDMCOUNT
349fde59
JK
731 # https://github.com/ClangBuiltLinux/linux/issues/1721
732 depends on (!KASAN || KASAN_HW_TAGS || CLANG_VERSION >= 170000) || !DEBUG_INFO
733 depends on (!KCOV || CLANG_VERSION >= 170000) || !DEBUG_INFO
dc5723b0 734 depends on !GCOV_KERNEL
dc5723b0
ST
735 help
736 The compiler and Kconfig options support building with Clang's
737 LTO.
738
739choice
740 prompt "Link Time Optimization (LTO)"
741 default LTO_NONE
742 help
743 This option enables Link Time Optimization (LTO), which allows the
744 compiler to optimize binaries globally.
745
746 If unsure, select LTO_NONE. Note that LTO is very resource-intensive
747 so it's disabled by default.
748
749config LTO_NONE
750 bool "None"
751 help
752 Build the kernel normally, without Link Time Optimization (LTO).
753
754config LTO_CLANG_FULL
755 bool "Clang Full LTO (EXPERIMENTAL)"
756 depends on HAS_LTO_CLANG
757 depends on !COMPILE_TEST
758 select LTO_CLANG
759 help
9f79ffc1
JH
760 This option enables Clang's full Link Time Optimization (LTO), which
761 allows the compiler to optimize the kernel globally. If you enable
762 this option, the compiler generates LLVM bitcode instead of ELF
763 object files, and the actual compilation from bitcode happens at
764 the LTO link step, which may take several minutes depending on the
765 kernel configuration. More information can be found from LLVM's
766 documentation:
dc5723b0
ST
767
768 https://llvm.org/docs/LinkTimeOptimization.html
769
770 During link time, this option can use a large amount of RAM, and
771 may take much longer than the ThinLTO option.
772
773config LTO_CLANG_THIN
774 bool "Clang ThinLTO (EXPERIMENTAL)"
775 depends on HAS_LTO_CLANG && ARCH_SUPPORTS_LTO_CLANG_THIN
776 select LTO_CLANG
777 help
778 This option enables Clang's ThinLTO, which allows for parallel
779 optimization and faster incremental compiles compared to the
780 CONFIG_LTO_CLANG_FULL option. More information can be found
781 from Clang's documentation:
782
783 https://clang.llvm.org/docs/ThinLTO.html
784
785 If unsure, say Y.
786endchoice
787
cf68fffb
ST
788config ARCH_SUPPORTS_CFI_CLANG
789 bool
790 help
791 An architecture should select this option if it can support Clang's
792 Control-Flow Integrity (CFI) checking.
793
89245600
ST
794config ARCH_USES_CFI_TRAPS
795 bool
796
cf68fffb
ST
797config CFI_CLANG
798 bool "Use Clang's Control Flow Integrity (CFI)"
89245600
ST
799 depends on ARCH_SUPPORTS_CFI_CLANG
800 depends on $(cc-option,-fsanitize=kcfi)
cf68fffb
ST
801 help
802 This option enables Clang’s forward-edge Control Flow Integrity
803 (CFI) checking, where the compiler injects a runtime check to each
804 indirect function call to ensure the target is a valid function with
805 the correct static type. This restricts possible call targets and
806 makes it more difficult for an attacker to exploit bugs that allow
807 the modification of stored function pointers. More information can be
808 found from Clang's documentation:
809
810 https://clang.llvm.org/docs/ControlFlowIntegrity.html
811
cf68fffb
ST
812config CFI_PERMISSIVE
813 bool "Use CFI in permissive mode"
814 depends on CFI_CLANG
815 help
816 When selected, Control Flow Integrity (CFI) violations result in a
817 warning instead of a kernel panic. This option should only be used
818 for finding indirect call type mismatches during development.
819
820 If unsure, say N.
821
0f60a8ef
KC
822config HAVE_ARCH_WITHIN_STACK_FRAMES
823 bool
824 help
825 An architecture should select this if it can walk the kernel stack
826 frames to determine if an object is part of either the arguments
827 or local variables (i.e. that it excludes saved return addresses,
828 and similar) by implementing an inline arch_within_stack_frames(),
829 which is used by CONFIG_HARDENED_USERCOPY.
830
24a9c541 831config HAVE_CONTEXT_TRACKING_USER
2b1d5024
FW
832 bool
833 help
91d1aa43
FW
834 Provide kernel/user boundaries probes necessary for subsystems
835 that need it, such as userspace RCU extended quiescent state.
490f561b
FW
836 Syscalls need to be wrapped inside user_exit()-user_enter(), either
837 optimized behind static key or through the slow path using TIF_NOHZ
838 flag. Exceptions handlers must be wrapped as well. Irqs are already
6f0e6c15 839 protected inside ct_irq_enter/ct_irq_exit() but preemption or signal
490f561b
FW
840 handling on irq exit still need to be protected.
841
24a9c541 842config HAVE_CONTEXT_TRACKING_USER_OFFSTACK
83c2da2e
FW
843 bool
844 help
845 Architecture neither relies on exception_enter()/exception_exit()
846 nor on schedule_user(). Also preempt_schedule_notrace() and
847 preempt_schedule_irq() can't be called in a preemptible section
848 while context tracking is CONTEXT_USER. This feature reflects a sane
849 entry implementation where the following requirements are met on
850 critical entry code, ie: before user_exit() or after user_enter():
851
852 - Critical entry code isn't preemptible (or better yet:
853 not interruptible).
493c1822 854 - No use of RCU read side critical sections, unless ct_nmi_enter()
83c2da2e
FW
855 got called.
856 - No use of instrumentation, unless instrumentation_begin() got
857 called.
858
490f561b
FW
859config HAVE_TIF_NOHZ
860 bool
861 help
862 Arch relies on TIF_NOHZ and syscall slow path to implement context
863 tracking calls to user_enter()/user_exit().
2b1d5024 864
b952741c
FW
865config HAVE_VIRT_CPU_ACCOUNTING
866 bool
867
2b91ec9f
FW
868config HAVE_VIRT_CPU_ACCOUNTING_IDLE
869 bool
870 help
871 Architecture has its own way to account idle CPU time and therefore
872 doesn't implement vtime_account_idle().
873
40565b5a
SG
874config ARCH_HAS_SCALED_CPUTIME
875 bool
876
554b0004
KH
877config HAVE_VIRT_CPU_ACCOUNTING_GEN
878 bool
879 default y if 64BIT
880 help
881 With VIRT_CPU_ACCOUNTING_GEN, cputime_t becomes 64-bit.
882 Before enabling this option, arch code must be audited
883 to ensure there are no races in concurrent read/write of
884 cputime_t. For example, reading/writing 64-bit cputime_t on
885 some 32-bit arches may require multiple accesses, so proper
886 locking is needed to protect against concurrent accesses.
887
fdf9c356
FW
888config HAVE_IRQ_TIME_ACCOUNTING
889 bool
890 help
891 Archs need to ensure they use a high enough resolution clock to
892 support irq time accounting and then call enable_sched_clock_irqtime().
893
c49dd340
KS
894config HAVE_MOVE_PUD
895 bool
896 help
897 Architectures that select this are able to move page tables at the
898 PUD level. If there are only 3 page table levels, the move effectively
899 happens at the PGD level.
900
2c91bd4a
JFG
901config HAVE_MOVE_PMD
902 bool
903 help
904 Archs that select this are able to move page tables at the PMD level.
905
15626062
GS
906config HAVE_ARCH_TRANSPARENT_HUGEPAGE
907 bool
908
a00cc7d9
MW
909config HAVE_ARCH_TRANSPARENT_HUGEPAGE_PUD
910 bool
911
0ddab1d2
TK
912config HAVE_ARCH_HUGE_VMAP
913 bool
914
121e6f32
NP
915#
916# Archs that select this would be capable of PMD-sized vmaps (i.e.,
559089e0
SL
917# arch_vmap_pmd_supported() returns true). The VM_ALLOW_HUGE_VMAP flag
918# must be used to enable allocations to use hugepages.
121e6f32
NP
919#
920config HAVE_ARCH_HUGE_VMALLOC
921 depends on HAVE_ARCH_HUGE_VMAP
922 bool
923
3876d4a3
AG
924config ARCH_WANT_HUGE_PMD_SHARE
925 bool
926
2f0584f3
RE
927# Archs that want to use pmd_mkwrite on kernel memory need it defined even
928# if there are no userspace memory management features that use it
929config ARCH_WANT_KERNEL_PMD_MKWRITE
930 bool
931
932config ARCH_WANT_PMD_MKWRITE
933 def_bool TRANSPARENT_HUGEPAGE || ARCH_WANT_KERNEL_PMD_MKWRITE
934
0f8975ec
PE
935config HAVE_ARCH_SOFT_DIRTY
936 bool
937
786d35d4
DH
938config HAVE_MOD_ARCH_SPECIFIC
939 bool
940 help
941 The arch uses struct mod_arch_specific to store data. Many arches
942 just need a simple module loader without arch specific data - those
943 should not enable this.
944
945config MODULES_USE_ELF_RELA
946 bool
947 help
948 Modules only use ELF RELA relocations. Modules with ELF REL
949 relocations will give an error.
950
951config MODULES_USE_ELF_REL
952 bool
953 help
954 Modules only use ELF REL relocations. Modules with ELF RELA
955 relocations will give an error.
956
01dc0386
CL
957config ARCH_WANTS_MODULES_DATA_IN_VMALLOC
958 bool
959 help
960 For architectures like powerpc/32 which have constraints on module
961 allocation and need to allocate module data outside of module area.
962
cc1f0274
FW
963config HAVE_IRQ_EXIT_ON_IRQ_STACK
964 bool
965 help
966 Architecture doesn't only execute the irq handler on the irq stack
967 but also irq_exit(). This way we can process softirqs on this irq
968 stack instead of switching to a new one when we call __do_softirq()
969 in the end of an hardirq.
970 This spares a stack switch and improves cache usage on softirq
971 processing.
972
cd1a41ce
TG
973config HAVE_SOFTIRQ_ON_OWN_STACK
974 bool
975 help
976 Architecture provides a function to run __do_softirq() on a
c226bc3c 977 separate stack.
cd1a41ce 978
8cbb2b50
SAS
979config SOFTIRQ_ON_OWN_STACK
980 def_bool HAVE_SOFTIRQ_ON_OWN_STACK && !PREEMPT_RT
981
12700c17
AB
982config ALTERNATE_USER_ADDRESS_SPACE
983 bool
984 help
985 Architectures set this when the CPU uses separate address
986 spaces for kernel and user space pointers. In this case, the
987 access_ok() check on a __user pointer is skipped.
988
235a8f02
KS
989config PGTABLE_LEVELS
990 int
991 default 2
992
2b68f6ca
KC
993config ARCH_HAS_ELF_RANDOMIZE
994 bool
995 help
996 An architecture supports choosing randomized locations for
997 stack, mmap, brk, and ET_DYN. Defined functions:
998 - arch_mmap_rnd()
204db6ed 999 - arch_randomize_brk()
2b68f6ca 1000
d07e2259
DC
1001config HAVE_ARCH_MMAP_RND_BITS
1002 bool
1003 help
1004 An arch should select this symbol if it supports setting a variable
1005 number of bits for use in establishing the base address for mmap
1006 allocations, has MMU enabled and provides values for both:
1007 - ARCH_MMAP_RND_BITS_MIN
1008 - ARCH_MMAP_RND_BITS_MAX
1009
5f56a5df
JS
1010config HAVE_EXIT_THREAD
1011 bool
1012 help
1013 An architecture implements exit_thread.
1014
d07e2259
DC
1015config ARCH_MMAP_RND_BITS_MIN
1016 int
1017
1018config ARCH_MMAP_RND_BITS_MAX
1019 int
1020
1021config ARCH_MMAP_RND_BITS_DEFAULT
1022 int
1023
1024config ARCH_MMAP_RND_BITS
1025 int "Number of bits to use for ASLR of mmap base address" if EXPERT
1026 range ARCH_MMAP_RND_BITS_MIN ARCH_MMAP_RND_BITS_MAX
1027 default ARCH_MMAP_RND_BITS_DEFAULT if ARCH_MMAP_RND_BITS_DEFAULT
1028 default ARCH_MMAP_RND_BITS_MIN
1029 depends on HAVE_ARCH_MMAP_RND_BITS
1030 help
1031 This value can be used to select the number of bits to use to
1032 determine the random offset to the base address of vma regions
1033 resulting from mmap allocations. This value will be bounded
1034 by the architecture's minimum and maximum supported values.
1035
1036 This value can be changed after boot using the
1037 /proc/sys/vm/mmap_rnd_bits tunable
1038
1039config HAVE_ARCH_MMAP_RND_COMPAT_BITS
1040 bool
1041 help
1042 An arch should select this symbol if it supports running applications
1043 in compatibility mode, supports setting a variable number of bits for
1044 use in establishing the base address for mmap allocations, has MMU
1045 enabled and provides values for both:
1046 - ARCH_MMAP_RND_COMPAT_BITS_MIN
1047 - ARCH_MMAP_RND_COMPAT_BITS_MAX
1048
1049config ARCH_MMAP_RND_COMPAT_BITS_MIN
1050 int
1051
1052config ARCH_MMAP_RND_COMPAT_BITS_MAX
1053 int
1054
1055config ARCH_MMAP_RND_COMPAT_BITS_DEFAULT
1056 int
1057
1058config ARCH_MMAP_RND_COMPAT_BITS
1059 int "Number of bits to use for ASLR of mmap base address for compatible applications" if EXPERT
1060 range ARCH_MMAP_RND_COMPAT_BITS_MIN ARCH_MMAP_RND_COMPAT_BITS_MAX
1061 default ARCH_MMAP_RND_COMPAT_BITS_DEFAULT if ARCH_MMAP_RND_COMPAT_BITS_DEFAULT
1062 default ARCH_MMAP_RND_COMPAT_BITS_MIN
1063 depends on HAVE_ARCH_MMAP_RND_COMPAT_BITS
1064 help
1065 This value can be used to select the number of bits to use to
1066 determine the random offset to the base address of vma regions
1067 resulting from mmap allocations for compatible applications This
1068 value will be bounded by the architecture's minimum and maximum
1069 supported values.
1070
1071 This value can be changed after boot using the
1072 /proc/sys/vm/mmap_rnd_compat_bits tunable
1073
1b028f78
DS
1074config HAVE_ARCH_COMPAT_MMAP_BASES
1075 bool
1076 help
1077 This allows 64bit applications to invoke 32-bit mmap() syscall
1078 and vice-versa 32-bit applications to call 64-bit mmap().
1079 Required for applications doing different bitness syscalls.
1080
1f0e290c
GR
1081config PAGE_SIZE_LESS_THAN_64KB
1082 def_bool y
1083 depends on !ARM64_64K_PAGES
1f0e290c
GR
1084 depends on !PAGE_SIZE_64KB
1085 depends on !PARISC_PAGE_SIZE_64KB
e4bbd20d
NC
1086 depends on PAGE_SIZE_LESS_THAN_256KB
1087
1088config PAGE_SIZE_LESS_THAN_256KB
1089 def_bool y
1f0e290c
GR
1090 depends on !PAGE_SIZE_256KB
1091
67f3977f
AG
1092# This allows to use a set of generic functions to determine mmap base
1093# address by giving priority to top-down scheme only if the process
1094# is not in legacy mode (compat task, unlimited stack size or
1095# sysctl_legacy_va_layout).
1096# Architecture that selects this option can provide its own version of:
1097# - STACK_RND_MASK
1098config ARCH_WANT_DEFAULT_TOPDOWN_MMAP_LAYOUT
1099 bool
1100 depends on MMU
e7142bf5 1101 select ARCH_HAS_ELF_RANDOMIZE
67f3977f 1102
03f16cd0
JP
1103config HAVE_OBJTOOL
1104 bool
1105
4ab7674f
JP
1106config HAVE_JUMP_LABEL_HACK
1107 bool
1108
22102f45
JP
1109config HAVE_NOINSTR_HACK
1110 bool
1111
489e355b
JP
1112config HAVE_NOINSTR_VALIDATION
1113 bool
1114
5f3da8c0
JP
1115config HAVE_UACCESS_VALIDATION
1116 bool
1117 select OBJTOOL
1118
b9ab5ebb
JP
1119config HAVE_STACK_VALIDATION
1120 bool
1121 help
03f16cd0
JP
1122 Architecture supports objtool compile-time frame pointer rule
1123 validation.
b9ab5ebb 1124
af085d90
JP
1125config HAVE_RELIABLE_STACKTRACE
1126 bool
1127 help
140d7e88
MB
1128 Architecture has either save_stack_trace_tsk_reliable() or
1129 arch_stack_walk_reliable() function which only returns a stack trace
1130 if it can guarantee the trace is reliable.
af085d90 1131
468a9428
GS
1132config HAVE_ARCH_HASH
1133 bool
1134 default n
1135 help
1136 If this is set, the architecture provides an <asm/hash.h>
1137 file which provides platform-specific implementations of some
1138 functions in <linux/hash.h> or fs/namei.c.
1139
666047fe
FT
1140config HAVE_ARCH_NVRAM_OPS
1141 bool
1142
3a495511
WBG
1143config ISA_BUS_API
1144 def_bool ISA
1145
d2125043
AV
1146#
1147# ABI hall of shame
1148#
1149config CLONE_BACKWARDS
1150 bool
1151 help
1152 Architecture has tls passed as the 4th argument of clone(2),
1153 not the 5th one.
1154
1155config CLONE_BACKWARDS2
1156 bool
1157 help
1158 Architecture has the first two arguments of clone(2) swapped.
1159
dfa9771a
MS
1160config CLONE_BACKWARDS3
1161 bool
1162 help
1163 Architecture has tls passed as the 3rd argument of clone(2),
1164 not the 5th one.
1165
eaca6eae
AV
1166config ODD_RT_SIGACTION
1167 bool
1168 help
1169 Architecture has unusual rt_sigaction(2) arguments
1170
0a0e8cdf
AV
1171config OLD_SIGSUSPEND
1172 bool
1173 help
1174 Architecture has old sigsuspend(2) syscall, of one-argument variety
1175
1176config OLD_SIGSUSPEND3
1177 bool
1178 help
1179 Even weirder antique ABI - three-argument sigsuspend(2)
1180
495dfbf7
AV
1181config OLD_SIGACTION
1182 bool
1183 help
1184 Architecture has old sigaction(2) syscall. Nope, not the same
1185 as OLD_SIGSUSPEND | OLD_SIGSUSPEND3 - alpha has sigsuspend(2),
1186 but fairly different variant of sigaction(2), thanks to OSF/1
1187 compatibility...
1188
1189config COMPAT_OLD_SIGACTION
1190 bool
1191
17435e5f 1192config COMPAT_32BIT_TIME
942437c9
AB
1193 bool "Provide system calls for 32-bit time_t"
1194 default !64BIT || COMPAT
17435e5f
DD
1195 help
1196 This enables 32 bit time_t support in addition to 64 bit time_t support.
1197 This is relevant on all 32-bit architectures, and 64-bit architectures
1198 as part of compat syscall handling.
1199
87a4c375
CH
1200config ARCH_NO_PREEMPT
1201 bool
1202
a50a3f4b
TG
1203config ARCH_SUPPORTS_RT
1204 bool
1205
fff7fb0b
ZZ
1206config CPU_NO_EFFICIENT_FFS
1207 def_bool n
1208
ba14a194
AL
1209config HAVE_ARCH_VMAP_STACK
1210 def_bool n
1211 help
1212 An arch should select this symbol if it can support kernel stacks
1213 in vmalloc space. This means:
1214
1215 - vmalloc space must be large enough to hold many kernel stacks.
1216 This may rule out many 32-bit architectures.
1217
1218 - Stacks in vmalloc space need to work reliably. For example, if
1219 vmap page tables are created on demand, either this mechanism
1220 needs to work while the stack points to a virtual address with
1221 unpopulated page tables or arch code (switch_to() and switch_mm(),
1222 most likely) needs to ensure that the stack's page table entries
1223 are populated before running on a possibly unpopulated stack.
1224
1225 - If the stack overflows into a guard page, something reasonable
1226 should happen. The definition of "reasonable" is flexible, but
1227 instantly rebooting without logging anything would be unfriendly.
1228
1229config VMAP_STACK
1230 default y
1231 bool "Use a virtually-mapped stack"
eafb149e 1232 depends on HAVE_ARCH_VMAP_STACK
38dd767d 1233 depends on !KASAN || KASAN_HW_TAGS || KASAN_VMALLOC
a7f7f624 1234 help
ba14a194
AL
1235 Enable this if you want the use virtually-mapped kernel stacks
1236 with guard pages. This causes kernel stack overflows to be
1237 caught immediately rather than causing difficult-to-diagnose
1238 corruption.
1239
38dd767d
AK
1240 To use this with software KASAN modes, the architecture must support
1241 backing virtual mappings with real shadow memory, and KASAN_VMALLOC
1242 must be enabled.
ba14a194 1243
39218ff4
KC
1244config HAVE_ARCH_RANDOMIZE_KSTACK_OFFSET
1245 def_bool n
1246 help
1247 An arch should select this symbol if it can support kernel stack
1248 offset randomization with calls to add_random_kstack_offset()
1249 during syscall entry and choose_random_kstack_offset() during
1250 syscall exit. Careful removal of -fstack-protector-strong and
1251 -fstack-protector should also be applied to the entry code and
1252 closely examined, as the artificial stack bump looks like an array
1253 to the compiler, so it will attempt to add canary checks regardless
1254 of the static branch state.
1255
8cb37a59
ME
1256config RANDOMIZE_KSTACK_OFFSET
1257 bool "Support for randomizing kernel stack offset on syscall entry" if EXPERT
1258 default y
39218ff4 1259 depends on HAVE_ARCH_RANDOMIZE_KSTACK_OFFSET
efa90c11 1260 depends on INIT_STACK_NONE || !CC_IS_CLANG || CLANG_VERSION >= 140000
39218ff4
KC
1261 help
1262 The kernel stack offset can be randomized (after pt_regs) by
1263 roughly 5 bits of entropy, frustrating memory corruption
1264 attacks that depend on stack address determinism or
8cb37a59
ME
1265 cross-syscall address exposures.
1266
1267 The feature is controlled via the "randomize_kstack_offset=on/off"
1268 kernel boot param, and if turned off has zero overhead due to its use
1269 of static branches (see JUMP_LABEL).
1270
1271 If unsure, say Y.
1272
1273config RANDOMIZE_KSTACK_OFFSET_DEFAULT
1274 bool "Default state of kernel stack offset randomization"
1275 depends on RANDOMIZE_KSTACK_OFFSET
1276 help
1277 Kernel stack offset randomization is controlled by kernel boot param
1278 "randomize_kstack_offset=on/off", and this config chooses the default
1279 boot state.
39218ff4 1280
ad21fc4f
LA
1281config ARCH_OPTIONAL_KERNEL_RWX
1282 def_bool n
1283
1284config ARCH_OPTIONAL_KERNEL_RWX_DEFAULT
1285 def_bool n
1286
1287config ARCH_HAS_STRICT_KERNEL_RWX
1288 def_bool n
1289
0f5bf6d0 1290config STRICT_KERNEL_RWX
ad21fc4f
LA
1291 bool "Make kernel text and rodata read-only" if ARCH_OPTIONAL_KERNEL_RWX
1292 depends on ARCH_HAS_STRICT_KERNEL_RWX
1293 default !ARCH_OPTIONAL_KERNEL_RWX || ARCH_OPTIONAL_KERNEL_RWX_DEFAULT
1294 help
1295 If this is set, kernel text and rodata memory will be made read-only,
1296 and non-text memory will be made non-executable. This provides
1297 protection against certain security exploits (e.g. executing the heap
1298 or modifying text)
1299
1300 These features are considered standard security practice these days.
1301 You should say Y here in almost all cases.
1302
1303config ARCH_HAS_STRICT_MODULE_RWX
1304 def_bool n
1305
0f5bf6d0 1306config STRICT_MODULE_RWX
ad21fc4f
LA
1307 bool "Set loadable kernel module data as NX and text as RO" if ARCH_OPTIONAL_KERNEL_RWX
1308 depends on ARCH_HAS_STRICT_MODULE_RWX && MODULES
1309 default !ARCH_OPTIONAL_KERNEL_RWX || ARCH_OPTIONAL_KERNEL_RWX_DEFAULT
1310 help
1311 If this is set, module text and rodata memory will be made read-only,
1312 and non-text memory will be made non-executable. This provides
1313 protection against certain security exploits (e.g. writing to text)
1314
ea8c64ac
CH
1315# select if the architecture provides an asm/dma-direct.h header
1316config ARCH_HAS_PHYS_TO_DMA
1317 bool
1318
04f264d3
PB
1319config HAVE_ARCH_COMPILER_H
1320 bool
1321 help
1322 An architecture can select this if it provides an
1323 asm/compiler.h header that should be included after
1324 linux/compiler-*.h in order to override macro definitions that those
1325 headers generally provide.
1326
271ca788
AB
1327config HAVE_ARCH_PREL32_RELOCATIONS
1328 bool
1329 help
1330 May be selected by an architecture if it supports place-relative
1331 32-bit relocations, both in the toolchain and in the module loader,
1332 in which case relative references can be used in special sections
1333 for PCI fixup, initcalls etc which are only half the size on 64 bit
1334 architectures, and don't require runtime relocation on relocatable
1335 kernels.
1336
ce9084ba
AB
1337config ARCH_USE_MEMREMAP_PROT
1338 bool
1339
fb346fd9
WL
1340config LOCK_EVENT_COUNTS
1341 bool "Locking event counts collection"
1342 depends on DEBUG_FS
a7f7f624 1343 help
fb346fd9
WL
1344 Enable light-weight counting of various locking related events
1345 in the system with minimal performance impact. This reduces
1346 the chance of application behavior change because of timing
1347 differences. The counts are reported via debugfs.
1348
5cf896fb
PC
1349# Select if the architecture has support for applying RELR relocations.
1350config ARCH_HAS_RELR
1351 bool
1352
1353config RELR
1354 bool "Use RELR relocation packing"
1355 depends on ARCH_HAS_RELR && TOOLS_SUPPORT_RELR
1356 default y
1357 help
1358 Store the kernel's dynamic relocations in the RELR relocation packing
1359 format. Requires a compatible linker (LLD supports this feature), as
1360 well as compatible NM and OBJCOPY utilities (llvm-nm and llvm-objcopy
1361 are compatible).
1362
0c9c1d56
TJB
1363config ARCH_HAS_MEM_ENCRYPT
1364 bool
1365
46b49b12
TL
1366config ARCH_HAS_CC_PLATFORM
1367 bool
1368
0e242208 1369config HAVE_SPARSE_SYSCALL_NR
9f79ffc1
JH
1370 bool
1371 help
1372 An architecture should select this if its syscall numbering is sparse
0e242208
HN
1373 to save space. For example, MIPS architecture has a syscall array with
1374 entries at 4000, 5000 and 6000 locations. This option turns on syscall
1375 related optimizations for a given architecture.
1376
d60d7de3
SS
1377config ARCH_HAS_VDSO_DATA
1378 bool
1379
115284d8
JP
1380config HAVE_STATIC_CALL
1381 bool
1382
9183c3f9
JP
1383config HAVE_STATIC_CALL_INLINE
1384 bool
1385 depends on HAVE_STATIC_CALL
03f16cd0 1386 select OBJTOOL
9183c3f9 1387
6ef869e0
MH
1388config HAVE_PREEMPT_DYNAMIC
1389 bool
99cf983c
MR
1390
1391config HAVE_PREEMPT_DYNAMIC_CALL
1392 bool
6ef869e0 1393 depends on HAVE_STATIC_CALL
99cf983c
MR
1394 select HAVE_PREEMPT_DYNAMIC
1395 help
9f79ffc1
JH
1396 An architecture should select this if it can handle the preemption
1397 model being selected at boot time using static calls.
99cf983c 1398
9f79ffc1
JH
1399 Where an architecture selects HAVE_STATIC_CALL_INLINE, any call to a
1400 preemption function will be patched directly.
99cf983c 1401
9f79ffc1
JH
1402 Where an architecture does not select HAVE_STATIC_CALL_INLINE, any
1403 call to a preemption function will go through a trampoline, and the
1404 trampoline will be patched.
99cf983c 1405
9f79ffc1
JH
1406 It is strongly advised to support inline static call to avoid any
1407 overhead.
99cf983c
MR
1408
1409config HAVE_PREEMPT_DYNAMIC_KEY
1410 bool
a0a12c3e 1411 depends on HAVE_ARCH_JUMP_LABEL
99cf983c 1412 select HAVE_PREEMPT_DYNAMIC
6ef869e0 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 keys.
99cf983c 1416
9f79ffc1
JH
1417 Each preemption function will be given an early return based on a
1418 static key. This should have slightly lower overhead than non-inline
1419 static calls, as this effectively inlines each trampoline into the
1420 start of its callee. This may avoid redundant work, and may
1421 integrate better with CFI schemes.
99cf983c 1422
9f79ffc1
JH
1423 This will have greater overhead than using inline static calls as
1424 the call to the preemption function cannot be entirely elided.
6ef869e0 1425
59612b24
NC
1426config ARCH_WANT_LD_ORPHAN_WARN
1427 bool
1428 help
1429 An arch should select this symbol once all linker sections are explicitly
1430 included, size-asserted, or discarded in the linker scripts. This is
1431 important because we never want expected sections to be placed heuristically
1432 by the linker, since the locations of such sections can change between linker
1433 versions.
1434
4f5b0c17
MR
1435config HAVE_ARCH_PFN_VALID
1436 bool
1437
5d6ad668
MR
1438config ARCH_SUPPORTS_DEBUG_PAGEALLOC
1439 bool
1440
df4e817b
PT
1441config ARCH_SUPPORTS_PAGE_TABLE_CHECK
1442 bool
1443
2ca408d9
BG
1444config ARCH_SPLIT_ARG64
1445 bool
1446 help
9f79ffc1
JH
1447 If a 32-bit architecture requires 64-bit arguments to be split into
1448 pairs of 32-bit arguments, select this option.
2ca408d9 1449
7facdc42
AV
1450config ARCH_HAS_ELFCORE_COMPAT
1451 bool
1452
58e106e7
BS
1453config ARCH_HAS_PARANOID_L1D_FLUSH
1454 bool
1455
d593d64f
PS
1456config ARCH_HAVE_TRACE_MMIO_ACCESS
1457 bool
1458
1bdda24c
TG
1459config DYNAMIC_SIGFRAME
1460 bool
1461
50468e43
JS
1462# Select, if arch has a named attribute group bound to NUMA device nodes.
1463config HAVE_ARCH_NODE_DEV_GROUP
1464 bool
1465
71ce1ab5
KH
1466config ARCH_HAS_HW_PTE_YOUNG
1467 bool
1468 help
1469 Architectures that select this option are capable of setting the
1470 accessed bit in PTE entries when using them as part of linear address
1471 translations. Architectures that require runtime check should select
1472 this option and override arch_has_hw_pte_young().
1473
eed9a328
YZ
1474config ARCH_HAS_NONLEAF_PMD_YOUNG
1475 bool
1476 help
1477 Architectures that select this option are capable of setting the
1478 accessed bit in non-leaf PMD entries when using them as part of linear
1479 address translations. Page table walkers that clear the accessed bit
1480 may use this capability to reduce their search space.
1481
2521f2c2 1482source "kernel/gcov/Kconfig"
45332b1b
MY
1483
1484source "scripts/gcc-plugins/Kconfig"
fa1b5d09 1485
d49a0626
PZ
1486config FUNCTION_ALIGNMENT_4B
1487 bool
1488
1489config FUNCTION_ALIGNMENT_8B
1490 bool
1491
1492config FUNCTION_ALIGNMENT_16B
1493 bool
1494
1495config FUNCTION_ALIGNMENT_32B
1496 bool
1497
1498config FUNCTION_ALIGNMENT_64B
1499 bool
1500
1501config FUNCTION_ALIGNMENT
1502 int
1503 default 64 if FUNCTION_ALIGNMENT_64B
1504 default 32 if FUNCTION_ALIGNMENT_32B
1505 default 16 if FUNCTION_ALIGNMENT_16B
1506 default 8 if FUNCTION_ALIGNMENT_8B
1507 default 4 if FUNCTION_ALIGNMENT_4B
1508 default 0
1509
22471e13 1510endmenu