# SPDX-License-Identifier: GPL-2.0## General architecture dependent options# ## Note: arch/$(SRCARCH)/Kconfig needs to be included first so that it can# override the default values in this file.#source "arch/$(SRCARCH)/Kconfig" menu "General architecture-dependent options" config CRASH_CORE	bool config KEXEC_CORE	select CRASH_CORE	bool config KEXEC_ELF	bool config HAVE_IMA_KEXEC	bool config HOTPLUG_SMT	bool config GENERIC_ENTRY       bool config OPROFILE	tristate "OProfile system profiling"	depends on PROFILING	depends on HAVE_OPROFILE	select RING_BUFFER	select RING_BUFFER_ALLOW_SWAP	help	  OProfile is a profiling system capable of profiling the	  whole system, include the kernel, kernel modules, libraries,	  and applications. 	  If unsure, say N. config OPROFILE_EVENT_MULTIPLEX	bool "OProfile multiplexing support (EXPERIMENTAL)"	default n	depends on OPROFILE && X86	help	  The number of hardware counters is limited. The multiplexing	  feature enables OProfile to gather more events than counters	  are provided by the hardware. This is realized by switching	  between events at a user specified time interval. 	  If unsure, say N. config HAVE_OPROFILE	bool config OPROFILE_NMI_TIMER	def_bool y	depends on PERF_EVENTS && HAVE_PERF_EVENTS_NMI && !PPC64 config KPROBES	bool "Kprobes"	depends on MODULES	depends on HAVE_KPROBES	select KALLSYMS	help	  Kprobes allows you to trap at almost any kernel address and	  execute a callback function.  register_kprobe() establishes	  a probepoint and specifies the callback.  Kprobes is useful	  for kernel debugging, non-intrusive instrumentation and testing.	  If in doubt, say "N". config JUMP_LABEL	bool "Optimize very unlikely/likely branches"	depends on HAVE_ARCH_JUMP_LABEL	depends on CC_HAS_ASM_GOTO	help	 This option enables a transparent branch optimization that	 makes certain almost-always-true or almost-always-false branch	 conditions even cheaper to execute within the kernel. 	 Certain performance-sensitive kernel code, such as trace points,	 scheduler functionality, networking code and KVM have such	 branches and include support for this optimization technique. 	 If it is detected that the compiler has support for "asm goto",	 the kernel will compile such branches with just a nop	 instruction. When the condition flag is toggled to true, the	 nop will be converted to a jump instruction to execute the	 conditional block of instructions. 	 This technique lowers overhead and stress on the branch prediction	 of the processor and generally makes the kernel faster. The update	 of the condition is slower, but those are always very rare. 	 ( On 32-bit x86, the necessary options added to the compiler	   flags may increase the size of the kernel slightly. ) config STATIC_KEYS_SELFTEST	bool "Static key selftest"	depends on JUMP_LABEL	help	  Boot time self-test of the branch patching code. config OPTPROBES	def_bool y	depends on KPROBES && HAVE_OPTPROBES	select TASKS_RCU if PREEMPTION config KPROBES_ON_FTRACE	def_bool y	depends on KPROBES && HAVE_KPROBES_ON_FTRACE	depends on DYNAMIC_FTRACE_WITH_REGS	help	 If function tracer is enabled and the arch supports full	 passing of pt_regs to function tracing, then kprobes can	 optimize on top of function tracing. config UPROBES	def_bool n	depends on ARCH_SUPPORTS_UPROBES	help	  Uprobes is the user-space counterpart to kprobes: they	  enable instrumentation applications (such as 'perf probe')	  to establish unintrusive probes in user-space binaries and	  libraries, by executing handler functions when the probes	  are hit by user-space applications. 	  ( These probes come in the form of single-byte breakpoints,	    managed by the kernel and kept transparent to the probed	    application. ) config HAVE_EFFICIENT_UNALIGNED_ACCESS	bool	help	  Some architectures are unable to perform unaligned accesses	  without the use of get_unaligned/put_unaligned. Others are	  unable to perform such accesses efficiently (e.g. trap on	  unaligned access and require fixing it up in the exception	  handler.) 	  This symbol should be selected by an architecture if it can	  perform unaligned accesses efficiently to allow different	  code paths to be selected for these cases. Some network	  drivers, for example, could opt to not fix up alignment	  problems with received packets if doing so would not help	  much. 	  See Documentation/core-api/unaligned-memory-access.rst for more	  information on the topic of unaligned memory accesses. config ARCH_USE_BUILTIN_BSWAP	bool	help	 Modern versions of GCC (since 4.4) have builtin functions	 for handling byte-swapping. Using these, instead of the old	 inline assembler that the architecture code provides in the	 __arch_bswapXX() macros, allows the compiler to see what's	 happening and offers more opportunity for optimisation. In	 particular, the compiler will be able to combine the byteswap	 with a nearby load or store and use load-and-swap or	 store-and-swap instructions if the architecture has them. It	 should almost *never* result in code which is worse than the	 hand-coded assembler in <asm/swab.h>.  But just in case it	 does, the use of the builtins is optional. 	 Any architecture with load-and-swap or store-and-swap	 instructions should set this. And it shouldn't hurt to set it	 on architectures that don't have such instructions. config KRETPROBES	def_bool y	depends on KPROBES && HAVE_KRETPROBES config USER_RETURN_NOTIFIER	bool	depends on HAVE_USER_RETURN_NOTIFIER	help	  Provide a kernel-internal notification when a cpu is about to	  switch to user mode. config HAVE_IOREMAP_PROT	bool config HAVE_KPROBES	bool config HAVE_KRETPROBES	bool config HAVE_OPTPROBES	bool config HAVE_KPROBES_ON_FTRACE	bool config HAVE_FUNCTION_ERROR_INJECTION	bool config HAVE_NMI	bool ## An arch should select this if it provides all these things:##	task_pt_regs()		in asm/processor.h or asm/ptrace.h#	arch_has_single_step()	if there is hardware single-step support#	arch_has_block_step()	if there is hardware block-step support#	asm/syscall.h		supplying asm-generic/syscall.h interface#	linux/regset.h		user_regset interfaces#	CORE_DUMP_USE_REGSET	#define'd in linux/elf.h#	TIF_SYSCALL_TRACE	calls tracehook_report_syscall_{entry,exit}#	TIF_NOTIFY_RESUME	calls tracehook_notify_resume()#	signal delivery		calls tracehook_signal_handler()#config HAVE_ARCH_TRACEHOOK	bool config HAVE_DMA_CONTIGUOUS	bool config GENERIC_SMP_IDLE_THREAD	bool config GENERIC_IDLE_POLL_SETUP	bool config ARCH_HAS_FORTIFY_SOURCE	bool	help	  An architecture should select this when it can successfully	  build and run with CONFIG_FORTIFY_SOURCE. ## Select if the arch provides a historic keepinit alias for the retain_initrd# command line option#config ARCH_HAS_KEEPINITRD	bool # Select if arch has all set_memory_ro/rw/x/nx() functions in asm/cacheflush.hconfig ARCH_HAS_SET_MEMORY	bool # Select if arch has all set_direct_map_invalid/default() functionsconfig ARCH_HAS_SET_DIRECT_MAP	bool ## Select if the architecture provides the arch_dma_set_uncached symbol to# either provide an uncached segement alias for a DMA allocation, or# to remap the page tables in place.#config ARCH_HAS_DMA_SET_UNCACHED	bool ## Select if the architectures provides the arch_dma_clear_uncached symbol# to undo an in-place page table remap for uncached access.#config ARCH_HAS_DMA_CLEAR_UNCACHED	bool # Select if arch init_task must go in the __init_task_data sectionconfig ARCH_TASK_STRUCT_ON_STACK	bool # Select if arch has its private alloc_task_struct() functionconfig ARCH_TASK_STRUCT_ALLOCATOR	bool config HAVE_ARCH_THREAD_STRUCT_WHITELIST	bool	depends on !ARCH_TASK_STRUCT_ALLOCATOR	help	  An architecture should select this to provide hardened usercopy	  knowledge about what region of the thread_struct should be	  whitelisted for copying to userspace. Normally this is only the	  FPU registers. Specifically, arch_thread_struct_whitelist()	  should be implemented. Without this, the entire thread_struct	  field in task_struct will be left whitelisted. # Select if arch has its private alloc_thread_stack() functionconfig ARCH_THREAD_STACK_ALLOCATOR	bool # Select if arch wants to size task_struct dynamically via arch_task_struct_size:config ARCH_WANTS_DYNAMIC_TASK_STRUCT	bool config ARCH_32BIT_OFF_T	bool	depends on !64BIT	help	  All new 32-bit architectures should have 64-bit off_t type on	  userspace side which corresponds to the loff_t kernel type. This	  is the requirement for modern ABIs. Some existing architectures	  still support 32-bit off_t. This option is enabled for all such	  architectures explicitly. config HAVE_ASM_MODVERSIONS	bool	help	  This symbol should be selected by an architecure if it provides	  <asm/asm-prototypes.h> to support the module versioning for symbols	  exported from assembly code. config HAVE_REGS_AND_STACK_ACCESS_API	bool	help	  This symbol should be selected by an architecure if it supports	  the API needed to access registers and stack entries from pt_regs,	  declared in asm/ptrace.h	  For example the kprobes-based event tracer needs this API. config HAVE_RSEQ	bool	depends on HAVE_REGS_AND_STACK_ACCESS_API	help	  This symbol should be selected by an architecture if it	  supports an implementation of restartable sequences. config HAVE_FUNCTION_ARG_ACCESS_API	bool	help	  This symbol should be selected by an architecure if it supports	  the API needed to access function arguments from pt_regs,	  declared in asm/ptrace.h config HAVE_HW_BREAKPOINT	bool	depends on PERF_EVENTS config HAVE_MIXED_BREAKPOINTS_REGS	bool	depends on HAVE_HW_BREAKPOINT	help	  Depending on the arch implementation of hardware breakpoints,	  some of them have separate registers for data and instruction	  breakpoints addresses, others have mixed registers to store	  them but define the access type in a control register.	  Select this option if your arch implements breakpoints under the	  latter fashion. config HAVE_USER_RETURN_NOTIFIER	bool config HAVE_PERF_EVENTS_NMI	bool	help	  System hardware can generate an NMI using the perf event	  subsystem.  Also has support for calculating CPU cycle events	  to determine how many clock cycles in a given period. config HAVE_HARDLOCKUP_DETECTOR_PERF	bool	depends on HAVE_PERF_EVENTS_NMI	help	  The arch chooses to use the generic perf-NMI-based hardlockup	  detector. Must define HAVE_PERF_EVENTS_NMI. config HAVE_NMI_WATCHDOG	depends on HAVE_NMI	bool	help	  The arch provides a low level NMI watchdog. It provides	  asm/nmi.h, and defines its own arch_touch_nmi_watchdog(). config HAVE_HARDLOCKUP_DETECTOR_ARCH	bool	select HAVE_NMI_WATCHDOG	help	  The arch chooses to provide its own hardlockup detector, which is	  a superset of the HAVE_NMI_WATCHDOG. It also conforms to config	  interfaces and parameters provided by hardlockup detector subsystem. config HAVE_PERF_REGS	bool	help	  Support selective register dumps for perf events. This includes	  bit-mapping of each registers and a unique architecture id. config HAVE_PERF_USER_STACK_DUMP	bool	help	  Support user stack dumps for perf event samples. This needs	  access to the user stack pointer which is not unified across	  architectures. config HAVE_ARCH_JUMP_LABEL	bool config HAVE_ARCH_JUMP_LABEL_RELATIVE	bool config MMU_GATHER_TABLE_FREE	bool config MMU_GATHER_RCU_TABLE_FREE	bool	select MMU_GATHER_TABLE_FREE config MMU_GATHER_PAGE_SIZE	bool config MMU_GATHER_NO_RANGE	bool config MMU_GATHER_NO_GATHER	bool	depends on MMU_GATHER_TABLE_FREE config ARCH_HAVE_NMI_SAFE_CMPXCHG	bool config HAVE_ALIGNED_STRUCT_PAGE	bool	help	  This makes sure that struct pages are double word aligned and that	  e.g. the SLUB allocator can perform double word atomic operations	  on a struct page for better performance. However selecting this	  might increase the size of a struct page by a word. config HAVE_CMPXCHG_LOCAL	bool config HAVE_CMPXCHG_DOUBLE	bool config ARCH_WEAK_RELEASE_ACQUIRE	bool config ARCH_WANT_IPC_PARSE_VERSION	bool config ARCH_WANT_COMPAT_IPC_PARSE_VERSION	bool config ARCH_WANT_OLD_COMPAT_IPC	select ARCH_WANT_COMPAT_IPC_PARSE_VERSION	bool config HAVE_ARCH_SECCOMP_FILTER	bool	help	  An arch should select this symbol if it provides all of these things:	  - syscall_get_arch()	  - syscall_get_arguments()	  - syscall_rollback()	  - syscall_set_return_value()	  - SIGSYS siginfo_t support	  - secure_computing is called from a ptrace_event()-safe context	  - secure_computing return value is checked and a return value of -1	    results in the system call being skipped immediately.	  - seccomp syscall wired up config SECCOMP_FILTER	def_bool y	depends on HAVE_ARCH_SECCOMP_FILTER && SECCOMP && NET	help	  Enable tasks to build secure computing environments defined	  in terms of Berkeley Packet Filter programs which implement	  task-defined system call filtering polices. 	  See Documentation/userspace-api/seccomp_filter.rst for details. config HAVE_ARCH_STACKLEAK	bool	help	  An architecture should select this if it has the code which	  fills the used part of the kernel stack with the STACKLEAK_POISON	  value before returning from system calls. config HAVE_STACKPROTECTOR	bool	help	  An arch should select this symbol if:	  - it has implemented a stack canary (e.g. __stack_chk_guard) config STACKPROTECTOR	bool "Stack Protector buffer overflow detection"	depends on HAVE_STACKPROTECTOR	depends on $(cc-option,-fstack-protector)	default y	help	  This option turns on the "stack-protector" GCC feature. This	  feature puts, at the beginning of functions, a canary value on	  the stack just before the return address, and validates	  the value just before actually returning.  Stack based buffer	  overflows (that need to overwrite this return address) now also	  overwrite the canary, which gets detected and the attack is then	  neutralized via a kernel panic. 	  Functions will have the stack-protector canary logic added if they	  have an 8-byte or larger character array on the stack. 

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