path: root/arch/Kconfig

# 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 SET_FS
	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 STATIC_CALL_SELFTEST
	bool "Static call selftest"
	depends on HAVE_STATIC_CALL
	help
	  Boot time self-test of the call 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_64BIT_ALIGNED_ACCESS
	def_bool 64BIT && !HAVE_EFFICIENT_UNALIGNED_ACCESS
	help
	  Some architectures require 64 bit accesses to be 64 bit
	  aligned, which also requires structs containing 64 bit values
	  to be 64 bit aligned too. This includes some 32 bit
	  architectures which can do 64 bit accesses, as well as 64 bit
	  architectures without unaligned access.

	  This symbol should be selected by an architecture if 64 bit
	  accesses are required to be 64 bit aligned in this way even
	  though it is not a 64 bit architecture.

	  See Documentation/unaligned-memory-access.txt for more
	  information on the topic of unaligned memory accesses.

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.h
config ARCH_HAS_SET_MEMORY
	bool

# Select if arch has all set_direct_map_invalid/default() functions
config ARCH_HAS_SET_DIRECT_MAP
	bool

#
# Select if the architecture provides the arch_dma_set_uncached symbol to
# either provide an uncached segment 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 section
config ARCH_TASK_STRUCT_ON_STACK
	bool

# Select if arch has its private alloc_task_struct() function
config 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() function
confi