1# SPDX-License-Identifier: GPL-2.0
  2#
  3# General architecture dependent options
  4#
  5
 
 
 
 
 
 
 
 
  6config CRASH_CORE
  7	bool
  8
  9config KEXEC_CORE
 10	select CRASH_CORE
 11	bool
 12
 
 
 
 13config HAVE_IMA_KEXEC
 14	bool
 15
 
 
 
 
 
 
 16config OPROFILE
 17	tristate "OProfile system profiling"
 18	depends on PROFILING
 19	depends on HAVE_OPROFILE
 20	select RING_BUFFER
 21	select RING_BUFFER_ALLOW_SWAP
 22	help
 23	  OProfile is a profiling system capable of profiling the
 24	  whole system, include the kernel, kernel modules, libraries,
 25	  and applications.
 26
 27	  If unsure, say N.
 28
 29config OPROFILE_EVENT_MULTIPLEX
 30	bool "OProfile multiplexing support (EXPERIMENTAL)"
 31	default n
 32	depends on OPROFILE && X86
 33	help
 34	  The number of hardware counters is limited. The multiplexing
 35	  feature enables OProfile to gather more events than counters
 36	  are provided by the hardware. This is realized by switching
 37	  between events at a user specified time interval.
 38
 39	  If unsure, say N.
 40
 41config HAVE_OPROFILE
 42	bool
 43
 44config OPROFILE_NMI_TIMER
 45	def_bool y
 46	depends on PERF_EVENTS && HAVE_PERF_EVENTS_NMI && !PPC64
 47
 48config KPROBES
 49	bool "Kprobes"
 50	depends on MODULES
 51	depends on HAVE_KPROBES
 52	select KALLSYMS
 53	help
 54	  Kprobes allows you to trap at almost any kernel address and
 55	  execute a callback function.  register_kprobe() establishes
 56	  a probepoint and specifies the callback.  Kprobes is useful
 57	  for kernel debugging, non-intrusive instrumentation and testing.
 58	  If in doubt, say "N".
 59
 60config JUMP_LABEL
 61       bool "Optimize very unlikely/likely branches"
 62       depends on HAVE_ARCH_JUMP_LABEL
 63       help
 64         This option enables a transparent branch optimization that
 
 65	 makes certain almost-always-true or almost-always-false branch
 66	 conditions even cheaper to execute within the kernel.
 67
 68	 Certain performance-sensitive kernel code, such as trace points,
 69	 scheduler functionality, networking code and KVM have such
 70	 branches and include support for this optimization technique.
 71
 72         If it is detected that the compiler has support for "asm goto",
 73	 the kernel will compile such branches with just a nop
 74	 instruction. When the condition flag is toggled to true, the
 75	 nop will be converted to a jump instruction to execute the
 76	 conditional block of instructions.
 77
 78	 This technique lowers overhead and stress on the branch prediction
 79	 of the processor and generally makes the kernel faster. The update
 80	 of the condition is slower, but those are always very rare.
 81
 82	 ( On 32-bit x86, the necessary options added to the compiler
 83	   flags may increase the size of the kernel slightly. )
 84
 85config STATIC_KEYS_SELFTEST
 86	bool "Static key selftest"
 87	depends on JUMP_LABEL
 88	help
 89	  Boot time self-test of the branch patching code.
 90
 91config OPTPROBES
 92	def_bool y
 93	depends on KPROBES && HAVE_OPTPROBES
 94	select TASKS_RCU if PREEMPT
 95
 96config KPROBES_ON_FTRACE
 97	def_bool y
 98	depends on KPROBES && HAVE_KPROBES_ON_FTRACE
 99	depends on DYNAMIC_FTRACE_WITH_REGS
100	help
101	 If function tracer is enabled and the arch supports full
102	 passing of pt_regs to function tracing, then kprobes can
103	 optimize on top of function tracing.
104
105config UPROBES
106	def_bool n
107	depends on ARCH_SUPPORTS_UPROBES
108	help
109	  Uprobes is the user-space counterpart to kprobes: they
110	  enable instrumentation applications (such as 'perf probe')
111	  to establish unintrusive probes in user-space binaries and
112	  libraries, by executing handler functions when the probes
113	  are hit by user-space applications.
114
115	  ( These probes come in the form of single-byte breakpoints,
116	    managed by the kernel and kept transparent to the probed
117	    application. )
118
119config HAVE_64BIT_ALIGNED_ACCESS
120	def_bool 64BIT && !HAVE_EFFICIENT_UNALIGNED_ACCESS
121	help
122	  Some architectures require 64 bit accesses to be 64 bit
123	  aligned, which also requires structs containing 64 bit values
124	  to be 64 bit aligned too. This includes some 32 bit
125	  architectures which can do 64 bit accesses, as well as 64 bit
126	  architectures without unaligned access.
127
128	  This symbol should be selected by an architecture if 64 bit
129	  accesses are required to be 64 bit aligned in this way even
130	  though it is not a 64 bit architecture.
131
132	  See Documentation/unaligned-memory-access.txt for more
133	  information on the topic of unaligned memory accesses.
134
135config HAVE_EFFICIENT_UNALIGNED_ACCESS
136	bool
137	help
138	  Some architectures are unable to perform unaligned accesses
139	  without the use of get_unaligned/put_unaligned. Others are
140	  unable to perform such accesses efficiently (e.g. trap on
141	  unaligned access and require fixing it up in the exception
142	  handler.)
143
144	  This symbol should be selected by an architecture if it can
145	  perform unaligned accesses efficiently to allow different
146	  code paths to be selected for these cases. Some network
147	  drivers, for example, could opt to not fix up alignment
148	  problems with received packets if doing so would not help
149	  much.
150
151	  See Documentation/unaligned-memory-access.txt for more
152	  information on the topic of unaligned memory accesses.
153
154config ARCH_USE_BUILTIN_BSWAP
155       bool
156       help
157	 Modern versions of GCC (since 4.4) have builtin functions
158	 for handling byte-swapping. Using these, instead of the old
159	 inline assembler that the architecture code provides in the
160	 __arch_bswapXX() macros, allows the compiler to see what's
161	 happening and offers more opportunity for optimisation. In
162	 particular, the compiler will be able to combine the byteswap
163	 with a nearby load or store and use load-and-swap or
164	 store-and-swap instructions if the architecture has them. It
165	 should almost *never* result in code which is worse than the
166	 hand-coded assembler in <asm/swab.h>.  But just in case it
167	 does, the use of the builtins is optional.
168
169	 Any architecture with load-and-swap or store-and-swap
170	 instructions should set this. And it shouldn't hurt to set it
171	 on architectures that don't have such instructions.
172
173config KRETPROBES
174	def_bool y
175	depends on KPROBES && HAVE_KRETPROBES
176
177config USER_RETURN_NOTIFIER
178	bool
179	depends on HAVE_USER_RETURN_NOTIFIER
180	help
181	  Provide a kernel-internal notification when a cpu is about to
182	  switch to user mode.
183
184config HAVE_IOREMAP_PROT
185	bool
186
187config HAVE_KPROBES
188	bool
189
190config HAVE_KRETPROBES
191	bool
192
193config HAVE_OPTPROBES
194	bool
195
196config HAVE_KPROBES_ON_FTRACE
197	bool
198
199config HAVE_FUNCTION_ERROR_INJECTION
200	bool
201
202config HAVE_NMI
203	bool
204
205#
206# An arch should select this if it provides all these things:
207#
208#	task_pt_regs()		in asm/processor.h or asm/ptrace.h
209#	arch_has_single_step()	if there is hardware single-step support
210#	arch_has_block_step()	if there is hardware block-step support
211#	asm/syscall.h		supplying asm-generic/syscall.h interface
212#	linux/regset.h		user_regset interfaces
213#	CORE_DUMP_USE_REGSET	#define'd in linux/elf.h
214#	TIF_SYSCALL_TRACE	calls tracehook_report_syscall_{entry,exit}
215#	TIF_NOTIFY_RESUME	calls tracehook_notify_resume()
216#	signal delivery		calls tracehook_signal_handler()
217#
218config HAVE_ARCH_TRACEHOOK
219	bool
220
221config HAVE_DMA_CONTIGUOUS
222	bool
223
224config GENERIC_SMP_IDLE_THREAD
225       bool
226
227config GENERIC_IDLE_POLL_SETUP
228       bool
229
230config ARCH_HAS_FORTIFY_SOURCE
231	bool
232	help
233	  An architecture should select this when it can successfully
234	  build and run with CONFIG_FORTIFY_SOURCE.
235
 
 
 
 
 
 
 
236# Select if arch has all set_memory_ro/rw/x/nx() functions in asm/cacheflush.h
237config ARCH_HAS_SET_MEMORY
238	bool
239
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
240# Select if arch init_task must go in the __init_task_data section
241config ARCH_TASK_STRUCT_ON_STACK
242       bool
243
244# Select if arch has its private alloc_task_struct() function
245config ARCH_TASK_STRUCT_ALLOCATOR
246	bool
247
248config HAVE_ARCH_THREAD_STRUCT_WHITELIST
249	bool
250	depends on !ARCH_TASK_STRUCT_ALLOCATOR
251	help
252	  An architecture should select this to provide hardened usercopy
253	  knowledge about what region of the thread_struct should be
254	  whitelisted for copying to userspace. Normally this is only the
255	  FPU registers. Specifically, arch_thread_struct_whitelist()
256	  should be implemented. Without this, the entire thread_struct
257	  field in task_struct will be left whitelisted.
258
259# Select if arch has its private alloc_thread_stack() function
260config ARCH_THREAD_STACK_ALLOCATOR
261	bool
262
263# Select if arch wants to size task_struct dynamically via arch_task_struct_size:
264config ARCH_WANTS_DYNAMIC_TASK_STRUCT
265	bool
266
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
267config HAVE_REGS_AND_STACK_ACCESS_API
268	bool
269	help
270	  This symbol should be selected by an architecure if it supports
271	  the API needed to access registers and stack entries from pt_regs,
272	  declared in asm/ptrace.h
273	  For example the kprobes-based event tracer needs this API.
274
275config HAVE_CLK
276	bool
 
277	help
278	  The <linux/clk.h> calls support software clock gating and
279	  thus are a key power management tool on many systems.
280
281config HAVE_DMA_API_DEBUG
282	bool
 
 
 
 
283
284config HAVE_HW_BREAKPOINT
285	bool
286	depends on PERF_EVENTS
287
288config HAVE_MIXED_BREAKPOINTS_REGS
289	bool
290	depends on HAVE_HW_BREAKPOINT
291	help
292	  Depending on the arch implementation of hardware breakpoints,
293	  some of them have separate registers for data and instruction
294	  breakpoints addresses, others have mixed registers to store
295	  them but define the access type in a control register.
296	  Select this option if your arch implements breakpoints under the
297	  latter fashion.
298
299config HAVE_USER_RETURN_NOTIFIER
300	bool
301
302config HAVE_PERF_EVENTS_NMI
303	bool
304	help
305	  System hardware can generate an NMI using the perf event
306	  subsystem.  Also has support for calculating CPU cycle events
307	  to determine how many clock cycles in a given period.
308
309config HAVE_HARDLOCKUP_DETECTOR_PERF
310	bool
311	depends on HAVE_PERF_EVENTS_NMI
312	help
313	  The arch chooses to use the generic perf-NMI-based hardlockup
314	  detector. Must define HAVE_PERF_EVENTS_NMI.
315
316config HAVE_NMI_WATCHDOG
317	depends on HAVE_NMI
318	bool
319	help
320	  The arch provides a low level NMI watchdog. It provides
321	  asm/nmi.h, and defines its own arch_touch_nmi_watchdog().
322
323config HAVE_HARDLOCKUP_DETECTOR_ARCH
324	bool
325	select HAVE_NMI_WATCHDOG
326	help
327	  The arch chooses to provide its own hardlockup detector, which is
328	  a superset of the HAVE_NMI_WATCHDOG. It also conforms to config
329	  interfaces and parameters provided by hardlockup detector subsystem.
330
331config HAVE_PERF_REGS
332	bool
333	help
334	  Support selective register dumps for perf events. This includes
335	  bit-mapping of each registers and a unique architecture id.
336
337config HAVE_PERF_USER_STACK_DUMP
338	bool
339	help
340	  Support user stack dumps for perf event samples. This needs
341	  access to the user stack pointer which is not unified across
342	  architectures.
343
344config HAVE_ARCH_JUMP_LABEL
345	bool
346
347config HAVE_RCU_TABLE_FREE
 
 
 
 
 
 
 
 
 
 
348	bool
349
 
 
 
 
 
 
 
350config ARCH_HAVE_NMI_SAFE_CMPXCHG
351	bool
352
353config HAVE_ALIGNED_STRUCT_PAGE
354	bool
355	help
356	  This makes sure that struct pages are double word aligned and that
357	  e.g. the SLUB allocator can perform double word atomic operations
358	  on a struct page for better performance. However selecting this
359	  might increase the size of a struct page by a word.
360
361config HAVE_CMPXCHG_LOCAL
362	bool
363
364config HAVE_CMPXCHG_DOUBLE
365	bool
366
367config ARCH_WEAK_RELEASE_ACQUIRE
368	bool
369
370config ARCH_WANT_IPC_PARSE_VERSION
371	bool
372
373config ARCH_WANT_COMPAT_IPC_PARSE_VERSION
374	bool
375
376config ARCH_WANT_OLD_COMPAT_IPC
377	select ARCH_WANT_COMPAT_IPC_PARSE_VERSION
378	bool
379
380config HAVE_ARCH_SECCOMP_FILTER
381	bool
382	help
383	  An arch should select this symbol if it provides all of these things:
384	  - syscall_get_arch()
385	  - syscall_get_arguments()
386	  - syscall_rollback()
387	  - syscall_set_return_value()
388	  - SIGSYS siginfo_t support
389	  - secure_computing is called from a ptrace_event()-safe context
390	  - secure_computing return value is checked and a return value of -1
391	    results in the system call being skipped immediately.
392	  - seccomp syscall wired up
393
394config SECCOMP_FILTER
395	def_bool y
396	depends on HAVE_ARCH_SECCOMP_FILTER && SECCOMP && NET
397	help
398	  Enable tasks to build secure computing environments defined
399	  in terms of Berkeley Packet Filter programs which implement
400	  task-defined system call filtering polices.
401
402	  See Documentation/prctl/seccomp_filter.txt for details.
403
404config HAVE_GCC_PLUGINS
405	bool
406	help
407	  An arch should select this symbol if it supports building with
408	  GCC plugins.
 
409
410menuconfig GCC_PLUGINS
411	bool "GCC plugins"
412	depends on HAVE_GCC_PLUGINS
413	depends on !COMPILE_TEST
414	help
415	  GCC plugins are loadable modules that provide extra features to the
416	  compiler. They are useful for runtime instrumentation and static analysis.
417
418	  See Documentation/gcc-plugins.txt for details.
419
420config GCC_PLUGIN_CYC_COMPLEXITY
421	bool "Compute the cyclomatic complexity of a function" if EXPERT
422	depends on GCC_PLUGINS
423	depends on !COMPILE_TEST
424	help
425	  The complexity M of a function's control flow graph is defined as:
426	   M = E - N + 2P
427	  where
428
429	  E = the number of edges
430	  N = the number of nodes
431	  P = the number of connected components (exit nodes).
432
433	  Enabling this plugin reports the complexity to stderr during the
434	  build. It mainly serves as a simple example of how to create a
435	  gcc plugin for the kernel.
436
437config GCC_PLUGIN_SANCOV
438	bool
439	depends on GCC_PLUGINS
440	help
441	  This plugin inserts a __sanitizer_cov_trace_pc() call at the start of
442	  basic blocks. It supports all gcc versions with plugin support (from
443	  gcc-4.5 on). It is based on the commit "Add fuzzing coverage support"
444	  by Dmitry Vyukov <dvyukov@google.com>.
445
446config GCC_PLUGIN_LATENT_ENTROPY
447	bool "Generate some entropy during boot and runtime"
448	depends on GCC_PLUGINS
449	help
450	  By saying Y here the kernel will instrument some kernel code to
451	  extract some entropy from both original and artificially created
452	  program state.  This will help especially embedded systems where
453	  there is little 'natural' source of entropy normally.  The cost
454	  is some slowdown of the boot process (about 0.5%) and fork and
455	  irq processing.
456
457	  Note that entropy extracted this way is not cryptographically
458	  secure!
459
460	  This plugin was ported from grsecurity/PaX. More information at:
461	   * https://grsecurity.net/
462	   * https://pax.grsecurity.net/
463
464config GCC_PLUGIN_STRUCTLEAK
465	bool "Force initialization of variables containing userspace addresses"
466	depends on GCC_PLUGINS
467	# Currently STRUCTLEAK inserts initialization out of live scope of
468	# variables from KASAN point of view. This leads to KASAN false
469	# positive reports. Prohibit this combination for now.
470	depends on !KASAN_EXTRA
471	help
472	  This plugin zero-initializes any structures containing a
473	  __user attribute. This can prevent some classes of information
474	  exposures.
475
476	  This plugin was ported from grsecurity/PaX. More information at:
477	   * https://grsecurity.net/
478	   * https://pax.grsecurity.net/
479
480config GCC_PLUGIN_STRUCTLEAK_BYREF_ALL
481	bool "Force initialize all struct type variables passed by reference"
482	depends on GCC_PLUGIN_STRUCTLEAK
483	help
484	  Zero initialize any struct type local variable that may be passed by
485	  reference without having been initialized.
486
487config GCC_PLUGIN_STRUCTLEAK_VERBOSE
488	bool "Report forcefully initialized variables"
489	depends on GCC_PLUGIN_STRUCTLEAK
490	depends on !COMPILE_TEST
491	help
492	  This option will cause a warning to be printed each time the
493	  structleak plugin finds a variable it thinks needs to be
494	  initialized. Since not all existing initializers are detected
495	  by the plugin, this can produce false positive warnings.
496
497config GCC_PLUGIN_RANDSTRUCT
498	bool "Randomize layout of sensitive kernel structures"
499	depends on GCC_PLUGINS
500	select MODVERSIONS if MODULES
501	help
502	  If you say Y here, the layouts of structures that are entirely
503	  function pointers (and have not been manually annotated with
504	  __no_randomize_layout), or structures that have been explicitly
505	  marked with __randomize_layout, will be randomized at compile-time.
506	  This can introduce the requirement of an additional information
507	  exposure vulnerability for exploits targeting these structure
508	  types.
509
510	  Enabling this feature will introduce some performance impact,
511	  slightly increase memory usage, and prevent the use of forensic
512	  tools like Volatility against the system (unless the kernel
513	  source tree isn't cleaned after kernel installation).
514
515	  The seed used for compilation is located at
516	  scripts/gcc-plgins/randomize_layout_seed.h.  It remains after
517	  a make clean to allow for external modules to be compiled with
518	  the existing seed and will be removed by a make mrproper or
519	  make distclean.
520
521	  Note that the implementation requires gcc 4.7 or newer.
522
523	  This plugin was ported from grsecurity/PaX. More information at:
524	   * https://grsecurity.net/
525	   * https://pax.grsecurity.net/
526
527config GCC_PLUGIN_RANDSTRUCT_PERFORMANCE
528	bool "Use cacheline-aware structure randomization"
529	depends on GCC_PLUGIN_RANDSTRUCT
530	depends on !COMPILE_TEST
531	help
532	  If you say Y here, the RANDSTRUCT randomization will make a
533	  best effort at restricting randomization to cacheline-sized
534	  groups of elements.  It will further not randomize bitfields
535	  in structures.  This reduces the performance hit of RANDSTRUCT
536	  at the cost of weakened randomization.
537
538config HAVE_CC_STACKPROTECTOR
539	bool
540	help
541	  An arch should select this symbol if:
542	  - its compiler supports the -fstack-protector option
543	  - it has implemented a stack canary (e.g. __stack_chk_guard)
544
545choice
546	prompt "Stack Protector buffer overflow detection"
547	depends on HAVE_CC_STACKPROTECTOR
548	default CC_STACKPROTECTOR_AUTO
 
549	help
550	  This option turns on the "stack-protector" GCC feature. This
551	  feature puts, at the beginning of functions, a canary value on
552	  the stack just before the return address, and validates
553	  the value just before actually returning.  Stack based buffer
554	  overflows (that need to overwrite this return address) now also
555	  overwrite the canary, which gets detected and the attack is then
556	  neutralized via a kernel panic.
557
558config CC_STACKPROTECTOR_NONE
559	bool "None"
560	help
561	  Disable "stack-protector" GCC feature.
562
563config CC_STACKPROTECTOR_REGULAR
564	bool "Regular"
565	help
566	  Functions will have the stack-protector canary logic added if they
567	  have an 8-byte or larger character array on the stack.
568
569	  This feature requires gcc version 4.2 or above, or a distribution
570	  gcc with the feature backported ("-fstack-protector").
571
572	  On an x86 "defconfig" build, this feature adds canary checks to
573	  about 3% of all kernel functions, which increases kernel code size
574	  by about 0.3%.
575
576config CC_STACKPROTECTOR_STRONG
577	bool "Strong"
 
 
 
578	help
579	  Functions will have the stack-protector canary logic added in any
580	  of the following conditions:
581
582	  - local variable's address used as part of the right hand side of an
583	    assignment or function argument
584	  - local variable is an array (or union containing an array),
585	    regardless of array type or length
586	  - uses register local variables
587
588	  This feature requires gcc version 4.9 or above, or a distribution
589	  gcc with the feature backported ("-fstack-protector-strong").
590
591	  On an x86 "defconfig" build, this feature adds canary checks to
592	  about 20% of all kernel functions, which increases the kernel code
593	  size by about 2%.
594
595config CC_STACKPROTECTOR_AUTO
596	bool "Automatic"
597	help
598	  If the compiler supports it, the best available stack-protector
599	  option will be chosen.
600
601endchoice
602
603config LD_DEAD_CODE_DATA_ELIMINATION
604	bool
605	help
606	  Select this if the architecture wants to do dead code and
607	  data elimination with the linker by compiling with
608	  -ffunction-sections -fdata-sections and linking with
609	  --gc-sections.
610
611	  This requires that the arch annotates or otherwise protects
612	  its external entry points from being discarded. Linker scripts
613	  must also merge .text.*, .data.*, and .bss.* correctly into
614	  output sections. Care must be taken not to pull in unrelated
615	  sections (e.g., '.text.init'). Typically '.' in section names
616	  is used to distinguish them from label names / C identifiers.
 
 
 
 
 
 
 
 
 
 
617
618config HAVE_ARCH_WITHIN_STACK_FRAMES
619	bool
620	help
621	  An architecture should select this if it can walk the kernel stack
622	  frames to determine if an object is part of either the arguments
623	  or local variables (i.e. that it excludes saved return addresses,
624	  and similar) by implementing an inline arch_within_stack_frames(),
625	  which is used by CONFIG_HARDENED_USERCOPY.
626
627config HAVE_CONTEXT_TRACKING
628	bool
629	help
630	  Provide kernel/user boundaries probes necessary for subsystems
631	  that need it, such as userspace RCU extended quiescent state.
632	  Syscalls need to be wrapped inside user_exit()-user_enter() through
633	  the slow path using TIF_NOHZ flag. Exceptions handlers must be
634	  wrapped as well. Irqs are already protected inside
635	  rcu_irq_enter/rcu_irq_exit() but preemption or signal handling on
636	  irq exit still need to be protected.
 
 
 
 
 
 
637
638config HAVE_VIRT_CPU_ACCOUNTING
639	bool
640
641config ARCH_HAS_SCALED_CPUTIME
642	bool
643
644config HAVE_VIRT_CPU_ACCOUNTING_GEN
645	bool
646	default y if 64BIT
647	help
648	  With VIRT_CPU_ACCOUNTING_GEN, cputime_t becomes 64-bit.
649	  Before enabling this option, arch code must be audited
650	  to ensure there are no races in concurrent read/write of
651	  cputime_t. For example, reading/writing 64-bit cputime_t on
652	  some 32-bit arches may require multiple accesses, so proper
653	  locking is needed to protect against concurrent accesses.
654
655
656config HAVE_IRQ_TIME_ACCOUNTING
657	bool
658	help
659	  Archs need to ensure they use a high enough resolution clock to
660	  support irq time accounting and then call enable_sched_clock_irqtime().
661
 
 
 
 
 
662config HAVE_ARCH_TRANSPARENT_HUGEPAGE
663	bool
664
665config HAVE_ARCH_TRANSPARENT_HUGEPAGE_PUD
666	bool
667
668config HAVE_ARCH_HUGE_VMAP
669	bool
670
 
 
 
671config HAVE_ARCH_SOFT_DIRTY
672	bool
673
674config HAVE_MOD_ARCH_SPECIFIC
675	bool
676	help
677	  The arch uses struct mod_arch_specific to store data.  Many arches
678	  just need a simple module loader without arch specific data - those
679	  should not enable this.
680
681config MODULES_USE_ELF_RELA
682	bool
683	help
684	  Modules only use ELF RELA relocations.  Modules with ELF REL
685	  relocations will give an error.
686
687config MODULES_USE_ELF_REL
688	bool
689	help
690	  Modules only use ELF REL relocations.  Modules with ELF RELA
691	  relocations will give an error.
692
693config HAVE_UNDERSCORE_SYMBOL_PREFIX
694	bool
695	help
696	  Some architectures generate an _ in front of C symbols; things like
697	  module loading and assembly files need to know about this.
698
699config HAVE_IRQ_EXIT_ON_IRQ_STACK
700	bool
701	help
702	  Architecture doesn't only execute the irq handler on the irq stack
703	  but also irq_exit(). This way we can process softirqs on this irq
704	  stack instead of switching to a new one when we call __do_softirq()
705	  in the end of an hardirq.
706	  This spares a stack switch and improves cache usage on softirq
707	  processing.
708
709config PGTABLE_LEVELS
710	int
711	default 2
712
713config ARCH_HAS_ELF_RANDOMIZE
714	bool
715	help
716	  An architecture supports choosing randomized locations for
717	  stack, mmap, brk, and ET_DYN. Defined functions:
718	  - arch_mmap_rnd()
719	  - arch_randomize_brk()
720
721config HAVE_ARCH_MMAP_RND_BITS
722	bool
723	help
724	  An arch should select this symbol if it supports setting a variable
725	  number of bits for use in establishing the base address for mmap
726	  allocations, has MMU enabled and provides values for both:
727	  - ARCH_MMAP_RND_BITS_MIN
728	  - ARCH_MMAP_RND_BITS_MAX
729
730config HAVE_EXIT_THREAD
731	bool
732	help
733	  An architecture implements exit_thread.
734
735config ARCH_MMAP_RND_BITS_MIN
736	int
737
738config ARCH_MMAP_RND_BITS_MAX
739	int
740
741config ARCH_MMAP_RND_BITS_DEFAULT
742	int
743
744config ARCH_MMAP_RND_BITS
745	int "Number of bits to use for ASLR of mmap base address" if EXPERT
746	range ARCH_MMAP_RND_BITS_MIN ARCH_MMAP_RND_BITS_MAX
747	default ARCH_MMAP_RND_BITS_DEFAULT if ARCH_MMAP_RND_BITS_DEFAULT
748	default ARCH_MMAP_RND_BITS_MIN
749	depends on HAVE_ARCH_MMAP_RND_BITS
750	help
751	  This value can be used to select the number of bits to use to
752	  determine the random offset to the base address of vma regions
753	  resulting from mmap allocations. This value will be bounded
754	  by the architecture's minimum and maximum supported values.
755
756	  This value can be changed after boot using the
757	  /proc/sys/vm/mmap_rnd_bits tunable
758
759config HAVE_ARCH_MMAP_RND_COMPAT_BITS
760	bool
761	help
762	  An arch should select this symbol if it supports running applications
763	  in compatibility mode, supports setting a variable number of bits for
764	  use in establishing the base address for mmap allocations, has MMU
765	  enabled and provides values for both:
766	  - ARCH_MMAP_RND_COMPAT_BITS_MIN
767	  - ARCH_MMAP_RND_COMPAT_BITS_MAX
768
769config ARCH_MMAP_RND_COMPAT_BITS_MIN
770	int
771
772config ARCH_MMAP_RND_COMPAT_BITS_MAX
773	int
774
775config ARCH_MMAP_RND_COMPAT_BITS_DEFAULT
776	int
777
778config ARCH_MMAP_RND_COMPAT_BITS
779	int "Number of bits to use for ASLR of mmap base address for compatible applications" if EXPERT
780	range ARCH_MMAP_RND_COMPAT_BITS_MIN ARCH_MMAP_RND_COMPAT_BITS_MAX
781	default ARCH_MMAP_RND_COMPAT_BITS_DEFAULT if ARCH_MMAP_RND_COMPAT_BITS_DEFAULT
782	default ARCH_MMAP_RND_COMPAT_BITS_MIN
783	depends on HAVE_ARCH_MMAP_RND_COMPAT_BITS
784	help
785	  This value can be used to select the number of bits to use to
786	  determine the random offset to the base address of vma regions
787	  resulting from mmap allocations for compatible applications This
788	  value will be bounded by the architecture's minimum and maximum
789	  supported values.
790
791	  This value can be changed after boot using the
792	  /proc/sys/vm/mmap_rnd_compat_bits tunable
793
794config HAVE_ARCH_COMPAT_MMAP_BASES
795	bool
796	help
797	  This allows 64bit applications to invoke 32-bit mmap() syscall
798	  and vice-versa 32-bit applications to call 64-bit mmap().
799	  Required for applications doing different bitness syscalls.
800
801config HAVE_COPY_THREAD_TLS
 
 
 
 
 
 
802	bool
803	help
804	  Architecture provides copy_thread_tls to accept tls argument via
805	  normal C parameter passing, rather than extracting the syscall
806	  argument from pt_regs.
807
808config HAVE_STACK_VALIDATION
809	bool
810	help
811	  Architecture supports the 'objtool check' host tool command, which
812	  performs compile-time stack metadata validation.
813
814config HAVE_RELIABLE_STACKTRACE
815	bool
816	help
817	  Architecture has a save_stack_trace_tsk_reliable() function which
818	  only returns a stack trace if it can guarantee the trace is reliable.
 
819
820config HAVE_ARCH_HASH
821	bool
822	default n
823	help
824	  If this is set, the architecture provides an <asm/hash.h>
825	  file which provides platform-specific implementations of some
826	  functions in <linux/hash.h> or fs/namei.c.
827
 
 
 
828config ISA_BUS_API
829	def_bool ISA
830
831#
832# ABI hall of shame
833#
834config CLONE_BACKWARDS
835	bool
836	help
837	  Architecture has tls passed as the 4th argument of clone(2),
838	  not the 5th one.
839
840config CLONE_BACKWARDS2
841	bool
842	help
843	  Architecture has the first two arguments of clone(2) swapped.
844
845config CLONE_BACKWARDS3
846	bool
847	help
848	  Architecture has tls passed as the 3rd argument of clone(2),
849	  not the 5th one.
850
851config ODD_RT_SIGACTION
852	bool
853	help
854	  Architecture has unusual rt_sigaction(2) arguments
855
856config OLD_SIGSUSPEND
857	bool
858	help
859	  Architecture has old sigsuspend(2) syscall, of one-argument variety
860
861config OLD_SIGSUSPEND3
862	bool
863	help
864	  Even weirder antique ABI - three-argument sigsuspend(2)
865
866config OLD_SIGACTION
867	bool
868	help
869	  Architecture has old sigaction(2) syscall.  Nope, not the same
870	  as OLD_SIGSUSPEND | OLD_SIGSUSPEND3 - alpha has sigsuspend(2),
871	  but fairly different variant of sigaction(2), thanks to OSF/1
872	  compatibility...
873
874config COMPAT_OLD_SIGACTION
875	bool
876
877config ARCH_NO_COHERENT_DMA_MMAP
 
 
 
 
 
 
 
 
 
 
 
878	bool
879
880config CPU_NO_EFFICIENT_FFS
881	def_bool n
882
883config HAVE_ARCH_VMAP_STACK
884	def_bool n
885	help
886	  An arch should select this symbol if it can support kernel stacks
887	  in vmalloc space.  This means:
888
889	  - vmalloc space must be large enough to hold many kernel stacks.
890	    This may rule out many 32-bit architectures.
891
892	  - Stacks in vmalloc space need to work reliably.  For example, if
893	    vmap page tables are created on demand, either this mechanism
894	    needs to work while the stack points to a virtual address with
895	    unpopulated page tables or arch code (switch_to() and switch_mm(),
896	    most likely) needs to ensure that the stack's page table entries
897	    are populated before running on a possibly unpopulated stack.
898
899	  - If the stack overflows into a guard page, something reasonable
900	    should happen.  The definition of "reasonable" is flexible, but
901	    instantly rebooting without logging anything would be unfriendly.
902
903config VMAP_STACK
904	default y
905	bool "Use a virtually-mapped stack"
906	depends on HAVE_ARCH_VMAP_STACK && !KASAN
907	---help---
 
908	  Enable this if you want the use virtually-mapped kernel stacks
909	  with guard pages.  This causes kernel stack overflows to be
910	  caught immediately rather than causing difficult-to-diagnose
911	  corruption.
912
913	  This is presently incompatible with KASAN because KASAN expects
914	  the stack to map directly to the KASAN shadow map using a formula
915	  that is incorrect if the stack is in vmalloc space.
916
917config ARCH_OPTIONAL_KERNEL_RWX
918	def_bool n
919
920config ARCH_OPTIONAL_KERNEL_RWX_DEFAULT
921	def_bool n
922
923config ARCH_HAS_STRICT_KERNEL_RWX
924	def_bool n
925
926config STRICT_KERNEL_RWX
927	bool "Make kernel text and rodata read-only" if ARCH_OPTIONAL_KERNEL_RWX
928	depends on ARCH_HAS_STRICT_KERNEL_RWX
929	default !ARCH_OPTIONAL_KERNEL_RWX || ARCH_OPTIONAL_KERNEL_RWX_DEFAULT
930	help
931	  If this is set, kernel text and rodata memory will be made read-only,
932	  and non-text memory will be made non-executable. This provides
933	  protection against certain security exploits (e.g. executing the heap
934	  or modifying text)
935
936	  These features are considered standard security practice these days.
937	  You should say Y here in almost all cases.
938
939config ARCH_HAS_STRICT_MODULE_RWX
940	def_bool n
941
942config STRICT_MODULE_RWX
943	bool "Set loadable kernel module data as NX and text as RO" if ARCH_OPTIONAL_KERNEL_RWX
944	depends on ARCH_HAS_STRICT_MODULE_RWX && MODULES
945	default !ARCH_OPTIONAL_KERNEL_RWX || ARCH_OPTIONAL_KERNEL_RWX_DEFAULT
946	help
947	  If this is set, module text and rodata memory will be made read-only,
948	  and non-text memory will be made non-executable. This provides
949	  protection against certain security exploits (e.g. writing to text)
950
951# select if the architecture provides an asm/dma-direct.h header
952config ARCH_HAS_PHYS_TO_DMA
953	bool
954
955config ARCH_HAS_REFCOUNT
 
 
 
 
 
 
 
 
956	bool
957	help
958	  An architecture selects this when it has implemented refcount_t
959	  using open coded assembly primitives that provide an optimized
960	  refcount_t implementation, possibly at the expense of some full
961	  refcount state checks of CONFIG_REFCOUNT_FULL=y.
962
963	  The refcount overflow check behavior, however, must be retained.
964	  Catching overflows is the primary security concern for protecting
965	  against bugs in reference counts.
966
967config REFCOUNT_FULL
968	bool "Perform full reference count validation at the expense of speed"
969	help
970	  Enabling this switches the refcounting infrastructure from a fast
971	  unchecked atomic_t implementation to a fully state checked
972	  implementation, which can be (slightly) slower but provides protections
973	  against various use-after-free conditions that can be used in
974	  security flaw exploits.
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
975
976source "kernel/gcov/Kconfig"

  1# SPDX-License-Identifier: GPL-2.0
  2#
  3# General architecture dependent options
  4#
  5
  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
 12menu "General architecture-dependent options"
 13
 14config CRASH_CORE
 15	bool
 16
 17config KEXEC_CORE
 18	select CRASH_CORE
 19	bool
 20
 21config KEXEC_ELF
 22	bool
 23
 24config HAVE_IMA_KEXEC
 25	bool
 26
 27config HOTPLUG_SMT
 28	bool
 29
 30config GENERIC_ENTRY
 31       bool
 32
 33config OPROFILE
 34	tristate "OProfile system profiling"
 35	depends on PROFILING
 36	depends on HAVE_OPROFILE
 37	select RING_BUFFER
 38	select RING_BUFFER_ALLOW_SWAP
 39	help
 40	  OProfile is a profiling system capable of profiling the
 41	  whole system, include the kernel, kernel modules, libraries,
 42	  and applications.
 43
 44	  If unsure, say N.
 45
 46config OPROFILE_EVENT_MULTIPLEX
 47	bool "OProfile multiplexing support (EXPERIMENTAL)"
 48	default n
 49	depends on OPROFILE && X86
 50	help
 51	  The number of hardware counters is limited. The multiplexing
 52	  feature enables OProfile to gather more events than counters
 53	  are provided by the hardware. This is realized by switching
 54	  between events at a user specified time interval.
 55
 56	  If unsure, say N.
 57
 58config HAVE_OPROFILE
 59	bool
 60
 61config OPROFILE_NMI_TIMER
 62	def_bool y
 63	depends on PERF_EVENTS && HAVE_PERF_EVENTS_NMI && !PPC64
 64
 65config KPROBES
 66	bool "Kprobes"
 67	depends on MODULES
 68	depends on HAVE_KPROBES
 69	select KALLSYMS
 70	help
 71	  Kprobes allows you to trap at almost any kernel address and
 72	  execute a callback function.  register_kprobe() establishes
 73	  a probepoint and specifies the callback.  Kprobes is useful
 74	  for kernel debugging, non-intrusive instrumentation and testing.
 75	  If in doubt, say "N".
 76
 77config JUMP_LABEL
 78	bool "Optimize very unlikely/likely branches"
 79	depends on HAVE_ARCH_JUMP_LABEL
 80	depends on CC_HAS_ASM_GOTO
 81	help
 82	 This option enables a transparent branch optimization that
 83	 makes certain almost-always-true or almost-always-false branch
 84	 conditions even cheaper to execute within the kernel.
 85
 86	 Certain performance-sensitive kernel code, such as trace points,
 87	 scheduler functionality, networking code and KVM have such
 88	 branches and include support for this optimization technique.
 89
 90	 If it is detected that the compiler has support for "asm goto",
 91	 the kernel will compile such branches with just a nop
 92	 instruction. When the condition flag is toggled to true, the
 93	 nop will be converted to a jump instruction to execute the
 94	 conditional block of instructions.
 95
 96	 This technique lowers overhead and stress on the branch prediction
 97	 of the processor and generally makes the kernel faster. The update
 98	 of the condition is slower, but those are always very rare.
 99
100	 ( On 32-bit x86, the necessary options added to the compiler
101	   flags may increase the size of the kernel slightly. )
102
103config STATIC_KEYS_SELFTEST
104	bool "Static key selftest"
105	depends on JUMP_LABEL
106	help
107	  Boot time self-test of the branch patching code.
108
109config OPTPROBES
110	def_bool y
111	depends on KPROBES && HAVE_OPTPROBES
112	select TASKS_RCU if PREEMPTION
113
114config KPROBES_ON_FTRACE
115	def_bool y
116	depends on KPROBES && HAVE_KPROBES_ON_FTRACE
117	depends on DYNAMIC_FTRACE_WITH_REGS
118	help
119	 If function tracer is enabled and the arch supports full
120	 passing of pt_regs to function tracing, then kprobes can
121	 optimize on top of function tracing.
122
123config UPROBES
124	def_bool n
125	depends on ARCH_SUPPORTS_UPROBES
126	help
127	  Uprobes is the user-space counterpart to kprobes: they
128	  enable instrumentation applications (such as 'perf probe')
129	  to establish unintrusive probes in user-space binaries and
130	  libraries, by executing handler functions when the probes
131	  are hit by user-space applications.
132
133	  ( These probes come in the form of single-byte breakpoints,
134	    managed by the kernel and kept transparent to the probed
135	    application. )
136
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
137config HAVE_EFFICIENT_UNALIGNED_ACCESS
138	bool
139	help
140	  Some architectures are unable to perform unaligned accesses
141	  without the use of get_unaligned/put_unaligned. Others are
142	  unable to perform such accesses efficiently (e.g. trap on
143	  unaligned access and require fixing it up in the exception
144	  handler.)
145
146	  This symbol should be selected by an architecture if it can
147	  perform unaligned accesses efficiently to allow different
148	  code paths to be selected for these cases. Some network
149	  drivers, for example, could opt to not fix up alignment
150	  problems with received packets if doing so would not help
151	  much.
152
153	  See Documentation/core-api/unaligned-memory-access.rst for more
154	  information on the topic of unaligned memory accesses.
155
156config ARCH_USE_BUILTIN_BSWAP
157	bool
158	help
159	 Modern versions of GCC (since 4.4) have builtin functions
160	 for handling byte-swapping. Using these, instead of the old
161	 inline assembler that the architecture code provides in the
162	 __arch_bswapXX() macros, allows the compiler to see what's
163	 happening and offers more opportunity for optimisation. In
164	 particular, the compiler will be able to combine the byteswap
165	 with a nearby load or store and use load-and-swap or
166	 store-and-swap instructions if the architecture has them. It
167	 should almost *never* result in code which is worse than the
168	 hand-coded assembler in <asm/swab.h>.  But just in case it
169	 does, the use of the builtins is optional.
170
171	 Any architecture with load-and-swap or store-and-swap
172	 instructions should set this. And it shouldn't hurt to set it
173	 on architectures that don't have such instructions.
174
175config KRETPROBES
176	def_bool y
177	depends on KPROBES && HAVE_KRETPROBES
178
179config USER_RETURN_NOTIFIER
180	bool
181	depends on HAVE_USER_RETURN_NOTIFIER
182	help
183	  Provide a kernel-internal notification when a cpu is about to
184	  switch to user mode.
185
186config HAVE_IOREMAP_PROT
187	bool
188
189config HAVE_KPROBES
190	bool
191
192config HAVE_KRETPROBES
193	bool
194
195config HAVE_OPTPROBES
196	bool
197
198config HAVE_KPROBES_ON_FTRACE
199	bool
200
201config HAVE_FUNCTION_ERROR_INJECTION
202	bool
203
204config HAVE_NMI
205	bool
206
207#
208# An arch should select this if it provides all these things:
209#
210#	task_pt_regs()		in asm/processor.h or asm/ptrace.h
211#	arch_has_single_step()	if there is hardware single-step support
212#	arch_has_block_step()	if there is hardware block-step support
213#	asm/syscall.h		supplying asm-generic/syscall.h interface
214#	linux/regset.h		user_regset interfaces
215#	CORE_DUMP_USE_REGSET	#define'd in linux/elf.h
216#	TIF_SYSCALL_TRACE	calls tracehook_report_syscall_{entry,exit}
217#	TIF_NOTIFY_RESUME	calls tracehook_notify_resume()
218#	signal delivery		calls tracehook_signal_handler()
219#
220config HAVE_ARCH_TRACEHOOK
221	bool
222
223config HAVE_DMA_CONTIGUOUS
224	bool
225
226config GENERIC_SMP_IDLE_THREAD
227	bool
228
229config GENERIC_IDLE_POLL_SETUP
230	bool
231
232config ARCH_HAS_FORTIFY_SOURCE
233	bool
234	help
235	  An architecture should select this when it can successfully
236	  build and run with CONFIG_FORTIFY_SOURCE.
237
238#
239# Select if the arch provides a historic keepinit alias for the retain_initrd
240# command line option
241#
242config ARCH_HAS_KEEPINITRD
243	bool
244
245# Select if arch has all set_memory_ro/rw/x/nx() functions in asm/cacheflush.h
246config ARCH_HAS_SET_MEMORY
247	bool
248
249# Select if arch has all set_direct_map_invalid/default() functions
250config ARCH_HAS_SET_DIRECT_MAP
251	bool
252
253#
254# Select if the architecture provides the arch_dma_set_uncached symbol to
255# either provide an uncached segement alias for a DMA allocation, or
256# to remap the page tables in place.
257#
258config ARCH_HAS_DMA_SET_UNCACHED
259	bool
260
261#
262# Select if the architectures provides the arch_dma_clear_uncached symbol
263# to undo an in-place page table remap for uncached access.
264#
265config ARCH_HAS_DMA_CLEAR_UNCACHED
266	bool
267
268# Select if arch init_task must go in the __init_task_data section
269config ARCH_TASK_STRUCT_ON_STACK
270	bool
271
272# Select if arch has its private alloc_task_struct() function
273config ARCH_TASK_STRUCT_ALLOCATOR
274	bool
275
276config HAVE_ARCH_THREAD_STRUCT_WHITELIST
277	bool
278	depends on !ARCH_TASK_STRUCT_ALLOCATOR
279	help
280	  An architecture should select this to provide hardened usercopy
281	  knowledge about what region of the thread_struct should be
282	  whitelisted for copying to userspace. Normally this is only the
283	  FPU registers. Specifically, arch_thread_struct_whitelist()
284	  should be implemented. Without this, the entire thread_struct
285	  field in task_struct will be left whitelisted.
286
287# Select if arch has its private alloc_thread_stack() function
288config ARCH_THREAD_STACK_ALLOCATOR
289	bool
290
291# Select if arch wants to size task_struct dynamically via arch_task_struct_size:
292config ARCH_WANTS_DYNAMIC_TASK_STRUCT
293	bool
294
295config ARCH_32BIT_OFF_T
296	bool
297	depends on !64BIT
298	help
299	  All new 32-bit architectures should have 64-bit off_t type on
300	  userspace side which corresponds to the loff_t kernel type. This
301	  is the requirement for modern ABIs. Some existing architectures
302	  still support 32-bit off_t. This option is enabled for all such
303	  architectures explicitly.
304
305config HAVE_ASM_MODVERSIONS
306	bool
307	help
308	  This symbol should be selected by an architecure if it provides
309	  <asm/asm-prototypes.h> to support the module versioning for symbols
310	  exported from assembly code.
311
312config HAVE_REGS_AND_STACK_ACCESS_API
313	bool
314	help
315	  This symbol should be selected by an architecure if it supports
316	  the API needed to access registers and stack entries from pt_regs,
317	  declared in asm/ptrace.h
318	  For example the kprobes-based event tracer needs this API.
319
320config HAVE_RSEQ
321	bool
322	depends on HAVE_REGS_AND_STACK_ACCESS_API
323	help
324	  This symbol should be selected by an architecture if it
325	  supports an implementation of restartable sequences.
326
327config HAVE_FUNCTION_ARG_ACCESS_API
328	bool
329	help
330	  This symbol should be selected by an architecure if it supports
331	  the API needed to access function arguments from pt_regs,
332	  declared in asm/ptrace.h
333
334config HAVE_HW_BREAKPOINT
335	bool
336	depends on PERF_EVENTS
337
338config HAVE_MIXED_BREAKPOINTS_REGS
339	bool
340	depends on HAVE_HW_BREAKPOINT
341	help
342	  Depending on the arch implementation of hardware breakpoints,
343	  some of them have separate registers for data and instruction
344	  breakpoints addresses, others have mixed registers to store
345	  them but define the access type in a control register.
346	  Select this option if your arch implements breakpoints under the
347	  latter fashion.
348
349config HAVE_USER_RETURN_NOTIFIER
350	bool
351
352config HAVE_PERF_EVENTS_NMI
353	bool
354	help
355	  System hardware can generate an NMI using the perf event
356	  subsystem.  Also has support for calculating CPU cycle events
357	  to determine how many clock cycles in a given period.
358
359config HAVE_HARDLOCKUP_DETECTOR_PERF
360	bool
361	depends on HAVE_PERF_EVENTS_NMI
362	help
363	  The arch chooses to use the generic perf-NMI-based hardlockup
364	  detector. Must define HAVE_PERF_EVENTS_NMI.
365
366config HAVE_NMI_WATCHDOG
367	depends on HAVE_NMI
368	bool
369	help
370	  The arch provides a low level NMI watchdog. It provides
371	  asm/nmi.h, and defines its own arch_touch_nmi_watchdog().
372
373config HAVE_HARDLOCKUP_DETECTOR_ARCH
374	bool
375	select HAVE_NMI_WATCHDOG
376	help
377	  The arch chooses to provide its own hardlockup detector, which is
378	  a superset of the HAVE_NMI_WATCHDOG. It also conforms to config
379	  interfaces and parameters provided by hardlockup detector subsystem.
380
381config HAVE_PERF_REGS
382	bool
383	help
384	  Support selective register dumps for perf events. This includes
385	  bit-mapping of each registers and a unique architecture id.
386
387config HAVE_PERF_USER_STACK_DUMP
388	bool
389	help
390	  Support user stack dumps for perf event samples. This needs
391	  access to the user stack pointer which is not unified across
392	  architectures.
393
394config HAVE_ARCH_JUMP_LABEL
395	bool
396
397config HAVE_ARCH_JUMP_LABEL_RELATIVE
398	bool
399
400config MMU_GATHER_TABLE_FREE
401	bool
402
403config MMU_GATHER_RCU_TABLE_FREE
404	bool
405	select MMU_GATHER_TABLE_FREE
406
407config MMU_GATHER_PAGE_SIZE
408	bool
409
410config MMU_GATHER_NO_RANGE
411	bool
412
413config MMU_GATHER_NO_GATHER
414	bool
415	depends on MMU_GATHER_TABLE_FREE
416
417config ARCH_HAVE_NMI_SAFE_CMPXCHG
418	bool
419
420config HAVE_ALIGNED_STRUCT_PAGE
421	bool
422	help
423	  This makes sure that struct pages are double word aligned and that
424	  e.g. the SLUB allocator can perform double word atomic operations
425	  on a struct page for better performance. However selecting this
426	  might increase the size of a struct page by a word.
427
428config HAVE_CMPXCHG_LOCAL
429	bool
430
431config HAVE_CMPXCHG_DOUBLE
432	bool
433
434config ARCH_WEAK_RELEASE_ACQUIRE
435	bool
436
437config ARCH_WANT_IPC_PARSE_VERSION
438	bool
439
440config ARCH_WANT_COMPAT_IPC_PARSE_VERSION
441	bool
442
443config ARCH_WANT_OLD_COMPAT_IPC
444	select ARCH_WANT_COMPAT_IPC_PARSE_VERSION
445	bool
446
447config HAVE_ARCH_SECCOMP_FILTER
448	bool
449	help
450	  An arch should select this symbol if it provides all of these things:
451	  - syscall_get_arch()
452	  - syscall_get_arguments()
453	  - syscall_rollback()
454	  - syscall_set_return_value()
455	  - SIGSYS siginfo_t support
456	  - secure_computing is called from a ptrace_event()-safe context
457	  - secure_computing return value is checked and a return value of -1
458	    results in the system call being skipped immediately.
459	  - seccomp syscall wired up
460
461config SECCOMP_FILTER
462	def_bool y
463	depends on HAVE_ARCH_SECCOMP_FILTER && SECCOMP && NET
464	help
465	  Enable tasks to build secure computing environments defined
466	  in terms of Berkeley Packet Filter programs which implement
467	  task-defined system call filtering polices.
468
469	  See Documentation/userspace-api/seccomp_filter.rst for details.
470
471config HAVE_ARCH_STACKLEAK
472	bool
473	help
474	  An architecture should select this if it has the code which
475	  fills the used part of the kernel stack with the STACKLEAK_POISON
476	  value before returning from system calls.
477
478config HAVE_STACKPROTECTOR
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
479	bool
480	help
481	  An arch should select this symbol if:
 
482	  - it has implemented a stack canary (e.g. __stack_chk_guard)
483
484config STACKPROTECTOR
485	bool "Stack Protector buffer overflow detection"
486	depends on HAVE_STACKPROTECTOR
487	depends on $(cc-option,-fstack-protector)
488	default y
489	help
490	  This option turns on the "stack-protector" GCC feature. This
491	  feature puts, at the beginning of functions, a canary value on
492	  the stack just before the return address, and validates
493	  the value just before actually returning.  Stack based buffer
494	  overflows (that need to overwrite this return address) now also
495	  overwrite the canary, which gets detected and the attack is then
496	  neutralized via a kernel panic.
497
 
 
 
 
 
 
 
 
498	  Functions will have the stack-protector canary logic added if they
499	  have an 8-byte or larger character array on the stack.
500
501	  This feature requires gcc version 4.2 or above, or a distribution
502	  gcc with the feature backported ("-fstack-protector").
503
504	  On an x86 "defconfig" build, this feature adds canary checks to
505	  about 3% of all kernel functions, which increases kernel code size
506	  by about 0.3%.
507
508config STACKPROTECTOR_STRONG
509	bool "Strong Stack Protector"
510	depends on STACKPROTECTOR
511	depends on $(cc-option,-fstack-protector-strong)
512	default y
513	help
514	  Functions will have the stack-protector canary logic added in any
515	  of the following conditions:
516
517	  - local variable's address used as part of the right hand side of an
518	    assignment or function argument
519	  - local variable is an array (or union containing an array),
520	    regardless of array type or length
521	  - uses register local variables
522
523	  This feature requires gcc version 4.9 or above, or a distribution
524	  gcc with the feature backported ("-fstack-protector-strong").
525
526	  On an x86 "defconfig" build, this feature adds canary checks to
527	  about 20% of all kernel functions, which increases the kernel code
528	  size by about 2%.
529
530config ARCH_SUPPORTS_SHADOW_CALL_STACK
 
 
 
 
 
 
 
 
531	bool
532	help
533	  An architecture should select this if it supports Clang's Shadow
534	  Call Stack and implements runtime support for shadow stack
535	  switching.
536
537config SHADOW_CALL_STACK
538	bool "Clang Shadow Call Stack"
539	depends on CC_IS_CLANG && ARCH_SUPPORTS_SHADOW_CALL_STACK
540	depends on DYNAMIC_FTRACE_WITH_REGS || !FUNCTION_GRAPH_TRACER
541	help
542	  This option enables Clang's Shadow Call Stack, which uses a
543	  shadow stack to protect function return addresses from being
544	  overwritten by an attacker. More information can be found in
545	  Clang's documentation:
546
547	    https://clang.llvm.org/docs/ShadowCallStack.html
548
549	  Note that security guarantees in the kernel differ from the
550	  ones documented for user space. The kernel must store addresses
551	  of shadow stacks in memory, which means an attacker capable of
552	  reading and writing arbitrary memory may be able to locate them
553	  and hijack control flow by modifying the stacks.
554
555config HAVE_ARCH_WITHIN_STACK_FRAMES
556	bool
557	help
558	  An architecture should select this if it can walk the kernel stack
559	  frames to determine if an object is part of either the arguments
560	  or local variables (i.e. that it excludes saved return addresses,
561	  and similar) by implementing an inline arch_within_stack_frames(),
562	  which is used by CONFIG_HARDENED_USERCOPY.
563
564config HAVE_CONTEXT_TRACKING
565	bool
566	help
567	  Provide kernel/user boundaries probes necessary for subsystems
568	  that need it, such as userspace RCU extended quiescent state.
569	  Syscalls need to be wrapped inside user_exit()-user_enter(), either
570	  optimized behind static key or through the slow path using TIF_NOHZ
571	  flag. Exceptions handlers must be wrapped as well. Irqs are already
572	  protected inside rcu_irq_enter/rcu_irq_exit() but preemption or signal
573	  handling on irq exit still need to be protected.
574
575config HAVE_TIF_NOHZ
576	bool
577	help
578	  Arch relies on TIF_NOHZ and syscall slow path to implement context
579	  tracking calls to user_enter()/user_exit().
580
581config HAVE_VIRT_CPU_ACCOUNTING
582	bool
583
584config ARCH_HAS_SCALED_CPUTIME
585	bool
586
587config HAVE_VIRT_CPU_ACCOUNTING_GEN
588	bool
589	default y if 64BIT
590	help
591	  With VIRT_CPU_ACCOUNTING_GEN, cputime_t becomes 64-bit.
592	  Before enabling this option, arch code must be audited
593	  to ensure there are no races in concurrent read/write of
594	  cputime_t. For example, reading/writing 64-bit cputime_t on
595	  some 32-bit arches may require multiple accesses, so proper
596	  locking is needed to protect against concurrent accesses.
597
598
599config HAVE_IRQ_TIME_ACCOUNTING
600	bool
601	help
602	  Archs need to ensure they use a high enough resolution clock to
603	  support irq time accounting and then call enable_sched_clock_irqtime().
604
605config HAVE_MOVE_PMD
606	bool
607	help
608	  Archs that select this are able to move page tables at the PMD level.
609
610config HAVE_ARCH_TRANSPARENT_HUGEPAGE
611	bool
612
613config HAVE_ARCH_TRANSPARENT_HUGEPAGE_PUD
614	bool
615
616config HAVE_ARCH_HUGE_VMAP
617	bool
618
619config ARCH_WANT_HUGE_PMD_SHARE
620	bool
621
622config HAVE_ARCH_SOFT_DIRTY
623	bool
624
625config HAVE_MOD_ARCH_SPECIFIC
626	bool
627	help
628	  The arch uses struct mod_arch_specific to store data.  Many arches
629	  just need a simple module loader without arch specific data - those
630	  should not enable this.
631
632config MODULES_USE_ELF_RELA
633	bool
634	help
635	  Modules only use ELF RELA relocations.  Modules with ELF REL
636	  relocations will give an error.
637
638config MODULES_USE_ELF_REL
639	bool
640	help
641	  Modules only use ELF REL relocations.  Modules with ELF RELA
642	  relocations will give an error.
643
 
 
 
 
 
 
644config HAVE_IRQ_EXIT_ON_IRQ_STACK
645	bool
646	help
647	  Architecture doesn't only execute the irq handler on the irq stack
648	  but also irq_exit(). This way we can process softirqs on this irq
649	  stack instead of switching to a new one when we call __do_softirq()
650	  in the end of an hardirq.
651	  This spares a stack switch and improves cache usage on softirq
652	  processing.
653
654config PGTABLE_LEVELS
655	int
656	default 2
657
658config ARCH_HAS_ELF_RANDOMIZE
659	bool
660	help
661	  An architecture supports choosing randomized locations for
662	  stack, mmap, brk, and ET_DYN. Defined functions:
663	  - arch_mmap_rnd()
664	  - arch_randomize_brk()
665
666config HAVE_ARCH_MMAP_RND_BITS
667	bool
668	help
669	  An arch should select this symbol if it supports setting a variable
670	  number of bits for use in establishing the base address for mmap
671	  allocations, has MMU enabled and provides values for both:
672	  - ARCH_MMAP_RND_BITS_MIN
673	  - ARCH_MMAP_RND_BITS_MAX
674
675config HAVE_EXIT_THREAD
676	bool
677	help
678	  An architecture implements exit_thread.
679
680config ARCH_MMAP_RND_BITS_MIN
681	int
682
683config ARCH_MMAP_RND_BITS_MAX
684	int
685
686config ARCH_MMAP_RND_BITS_DEFAULT
687	int
688
689config ARCH_MMAP_RND_BITS
690	int "Number of bits to use for ASLR of mmap base address" if EXPERT
691	range ARCH_MMAP_RND_BITS_MIN ARCH_MMAP_RND_BITS_MAX
692	default ARCH_MMAP_RND_BITS_DEFAULT if ARCH_MMAP_RND_BITS_DEFAULT
693	default ARCH_MMAP_RND_BITS_MIN
694	depends on HAVE_ARCH_MMAP_RND_BITS
695	help
696	  This value can be used to select the number of bits to use to
697	  determine the random offset to the base address of vma regions
698	  resulting from mmap allocations. This value will be bounded
699	  by the architecture's minimum and maximum supported values.
700
701	  This value can be changed after boot using the
702	  /proc/sys/vm/mmap_rnd_bits tunable
703
704config HAVE_ARCH_MMAP_RND_COMPAT_BITS
705	bool
706	help
707	  An arch should select this symbol if it supports running applications
708	  in compatibility mode, supports setting a variable number of bits for
709	  use in establishing the base address for mmap allocations, has MMU
710	  enabled and provides values for both:
711	  - ARCH_MMAP_RND_COMPAT_BITS_MIN
712	  - ARCH_MMAP_RND_COMPAT_BITS_MAX
713
714config ARCH_MMAP_RND_COMPAT_BITS_MIN
715	int
716
717config ARCH_MMAP_RND_COMPAT_BITS_MAX
718	int
719
720config ARCH_MMAP_RND_COMPAT_BITS_DEFAULT
721	int
722
723config ARCH_MMAP_RND_COMPAT_BITS
724	int "Number of bits to use for ASLR of mmap base address for compatible applications" if EXPERT
725	range ARCH_MMAP_RND_COMPAT_BITS_MIN ARCH_MMAP_RND_COMPAT_BITS_MAX
726	default ARCH_MMAP_RND_COMPAT_BITS_DEFAULT if ARCH_MMAP_RND_COMPAT_BITS_DEFAULT
727	default ARCH_MMAP_RND_COMPAT_BITS_MIN
728	depends on HAVE_ARCH_MMAP_RND_COMPAT_BITS
729	help
730	  This value can be used to select the number of bits to use to
731	  determine the random offset to the base address of vma regions
732	  resulting from mmap allocations for compatible applications This
733	  value will be bounded by the architecture's minimum and maximum
734	  supported values.
735
736	  This value can be changed after boot using the
737	  /proc/sys/vm/mmap_rnd_compat_bits tunable
738
739config HAVE_ARCH_COMPAT_MMAP_BASES
740	bool
741	help
742	  This allows 64bit applications to invoke 32-bit mmap() syscall
743	  and vice-versa 32-bit applications to call 64-bit mmap().
744	  Required for applications doing different bitness syscalls.
745
746# This allows to use a set of generic functions to determine mmap base
747# address by giving priority to top-down scheme only if the process
748# is not in legacy mode (compat task, unlimited stack size or
749# sysctl_legacy_va_layout).
750# Architecture that selects this option can provide its own version of:
751# - STACK_RND_MASK
752config ARCH_WANT_DEFAULT_TOPDOWN_MMAP_LAYOUT
753	bool
754	depends on MMU
755	select ARCH_HAS_ELF_RANDOMIZE
 
 
756
757config HAVE_STACK_VALIDATION
758	bool
759	help
760	  Architecture supports the 'objtool check' host tool command, which
761	  performs compile-time stack metadata validation.
762
763config HAVE_RELIABLE_STACKTRACE
764	bool
765	help
766	  Architecture has either save_stack_trace_tsk_reliable() or
767	  arch_stack_walk_reliable() function which only returns a stack trace
768	  if it can guarantee the trace is reliable.
769
770config HAVE_ARCH_HASH
771	bool
772	default n
773	help
774	  If this is set, the architecture provides an <asm/hash.h>
775	  file which provides platform-specific implementations of some
776	  functions in <linux/hash.h> or fs/namei.c.
777
778config HAVE_ARCH_NVRAM_OPS
779	bool
780
781config ISA_BUS_API
782	def_bool ISA
783
784#
785# ABI hall of shame
786#
787config CLONE_BACKWARDS
788	bool
789	help
790	  Architecture has tls passed as the 4th argument of clone(2),
791	  not the 5th one.
792
793config CLONE_BACKWARDS2
794	bool
795	help
796	  Architecture has the first two arguments of clone(2) swapped.
797
798config CLONE_BACKWARDS3
799	bool
800	help
801	  Architecture has tls passed as the 3rd argument of clone(2),
802	  not the 5th one.
803
804config ODD_RT_SIGACTION
805	bool
806	help
807	  Architecture has unusual rt_sigaction(2) arguments
808
809config OLD_SIGSUSPEND
810	bool
811	help
812	  Architecture has old sigsuspend(2) syscall, of one-argument variety
813
814config OLD_SIGSUSPEND3
815	bool
816	help
817	  Even weirder antique ABI - three-argument sigsuspend(2)
818
819config OLD_SIGACTION
820	bool
821	help
822	  Architecture has old sigaction(2) syscall.  Nope, not the same
823	  as OLD_SIGSUSPEND | OLD_SIGSUSPEND3 - alpha has sigsuspend(2),
824	  but fairly different variant of sigaction(2), thanks to OSF/1
825	  compatibility...
826
827config COMPAT_OLD_SIGACTION
828	bool
829
830config COMPAT_32BIT_TIME
831	bool "Provide system calls for 32-bit time_t"
832	default !64BIT || COMPAT
833	help
834	  This enables 32 bit time_t support in addition to 64 bit time_t support.
835	  This is relevant on all 32-bit architectures, and 64-bit architectures
836	  as part of compat syscall handling.
837
838config ARCH_NO_PREEMPT
839	bool
840
841config ARCH_SUPPORTS_RT
842	bool
843
844config CPU_NO_EFFICIENT_FFS
845	def_bool n
846
847config HAVE_ARCH_VMAP_STACK
848	def_bool n
849	help
850	  An arch should select this symbol if it can support kernel stacks
851	  in vmalloc space.  This means:
852
853	  - vmalloc space must be large enough to hold many kernel stacks.
854	    This may rule out many 32-bit architectures.
855
856	  - Stacks in vmalloc space need to work reliably.  For example, if
857	    vmap page tables are created on demand, either this mechanism
858	    needs to work while the stack points to a virtual address with
859	    unpopulated page tables or arch code (switch_to() and switch_mm(),
860	    most likely) needs to ensure that the stack's page table entries
861	    are populated before running on a possibly unpopulated stack.
862
863	  - If the stack overflows into a guard page, something reasonable
864	    should happen.  The definition of "reasonable" is flexible, but
865	    instantly rebooting without logging anything would be unfriendly.
866
867config VMAP_STACK
868	default y
869	bool "Use a virtually-mapped stack"
870	depends on HAVE_ARCH_VMAP_STACK
871	depends on !KASAN || KASAN_VMALLOC
872	help
873	  Enable this if you want the use virtually-mapped kernel stacks
874	  with guard pages.  This causes kernel stack overflows to be
875	  caught immediately rather than causing difficult-to-diagnose
876	  corruption.
877
878	  To use this with KASAN, the architecture must support backing
879	  virtual mappings with real shadow memory, and KASAN_VMALLOC must
880	  be enabled.
881
882config ARCH_OPTIONAL_KERNEL_RWX
883	def_bool n
884
885config ARCH_OPTIONAL_KERNEL_RWX_DEFAULT
886	def_bool n
887
888config ARCH_HAS_STRICT_KERNEL_RWX
889	def_bool n
890
891config STRICT_KERNEL_RWX
892	bool "Make kernel text and rodata read-only" if ARCH_OPTIONAL_KERNEL_RWX
893	depends on ARCH_HAS_STRICT_KERNEL_RWX
894	default !ARCH_OPTIONAL_KERNEL_RWX || ARCH_OPTIONAL_KERNEL_RWX_DEFAULT
895	help
896	  If this is set, kernel text and rodata memory will be made read-only,
897	  and non-text memory will be made non-executable. This provides
898	  protection against certain security exploits (e.g. executing the heap
899	  or modifying text)
900
901	  These features are considered standard security practice these days.
902	  You should say Y here in almost all cases.
903
904config ARCH_HAS_STRICT_MODULE_RWX
905	def_bool n
906
907config STRICT_MODULE_RWX
908	bool "Set loadable kernel module data as NX and text as RO" if ARCH_OPTIONAL_KERNEL_RWX
909	depends on ARCH_HAS_STRICT_MODULE_RWX && MODULES
910	default !ARCH_OPTIONAL_KERNEL_RWX || ARCH_OPTIONAL_KERNEL_RWX_DEFAULT
911	help
912	  If this is set, module text and rodata memory will be made read-only,
913	  and non-text memory will be made non-executable. This provides
914	  protection against certain security exploits (e.g. writing to text)
915
916# select if the architecture provides an asm/dma-direct.h header
917config ARCH_HAS_PHYS_TO_DMA
918	bool
919
920config HAVE_ARCH_COMPILER_H
921	bool
922	help
923	  An architecture can select this if it provides an
924	  asm/compiler.h header that should be included after
925	  linux/compiler-*.h in order to override macro definitions that those
926	  headers generally provide.
927
928config HAVE_ARCH_PREL32_RELOCATIONS
929	bool
930	help
931	  May be selected by an architecture if it supports place-relative
932	  32-bit relocations, both in the toolchain and in the module loader,
933	  in which case relative references can be used in special sections
934	  for PCI fixup, initcalls etc which are only half the size on 64 bit
935	  architectures, and don't require runtime relocation on relocatable
936	  kernels.
937
938config ARCH_USE_MEMREMAP_PROT
939	bool
940
941config LOCK_EVENT_COUNTS
942	bool "Locking event counts collection"
943	depends on DEBUG_FS
944	help
945	  Enable light-weight counting of various locking related events
946	  in the system with minimal performance impact. This reduces
947	  the chance of application behavior change because of timing
948	  differences. The counts are reported via debugfs.
949
950# Select if the architecture has support for applying RELR relocations.
951config ARCH_HAS_RELR
952	bool
953
954config RELR
955	bool "Use RELR relocation packing"
956	depends on ARCH_HAS_RELR && TOOLS_SUPPORT_RELR
957	default y
958	help
959	  Store the kernel's dynamic relocations in the RELR relocation packing
960	  format. Requires a compatible linker (LLD supports this feature), as
961	  well as compatible NM and OBJCOPY utilities (llvm-nm and llvm-objcopy
962	  are compatible).
963
964config ARCH_HAS_MEM_ENCRYPT
965	bool
966
967config HAVE_SPARSE_SYSCALL_NR
968       bool
969       help
970          An architecture should select this if its syscall numbering is sparse
971	  to save space. For example, MIPS architecture has a syscall array with
972	  entries at 4000, 5000 and 6000 locations. This option turns on syscall
973	  related optimizations for a given architecture.
974
975config ARCH_HAS_VDSO_DATA
976	bool
977
978source "kernel/gcov/Kconfig"
979
980source "scripts/gcc-plugins/Kconfig"
981
982endmenu