# 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 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/core-api/unaligned-memory-access.rst 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 ARCH_CORRECT_STACKTRACE_ON_KRETPROBE
        bool
        help
          Since kretprobes modifies return address on the stack, the
          stacktrace may see the kretprobe trampoline address instead
          of correct one. If the architecture stacktrace code and
          unwinder can adjust such entries, select this configuration.

config HAVE_FUNCTION_ERROR_INJECTION
        bool

config HAVE_NMI
        bool

config TRACE_IRQFLAGS_SUPPORT
        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
config 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_WANTS_NO_INSTR
        bool
        help
          An architecture should select this if the noinstr macro is being used on
          functions to denote that the toolchain should avoid instrumenting such
          functions and is required for correctness.

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.

# Selected by 64 bit architectures which have a 32 bit f_tinode in struct ustat
config ARCH_32BIT_USTAT_F_TINODE
        bool

config HAVE_ASM_MODVERSIONS
        bool
        help
          This symbol should be selected by an architecture 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 architecture 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 architecture 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_WANT_IRQS_OFF_ACTIVATE_MM
        bool
        help
          Temporary select until all architectures can be converted to have
          irqs disabled over activate_mm. Architectures that do IPI based TLB
          shootdowns should enable this.

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
        bool
        help
          An arch should select this symbol to support seccomp mode 1 (the fixed
          syscall policy), and must provide an overrides for __NR_seccomp_sigreturn,
          and compat syscalls if the asm-generic/seccomp.h defaults need adjustment:
          - __NR_seccomp_read_32
          - __NR_seccomp_write_32
          - __NR_seccomp_exit_32
          - __NR_seccomp_sigreturn_32

config HAVE_ARCH_SECCOMP_FILTER
        bool
        select HAVE_ARCH_SECCOMP
        help
          An arch should select this symbol if it provides all of these things:
          - all the requirements for HAVE_ARCH_SECCOMP
          - 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
          - if !HAVE_SPARSE_SYSCALL_NR, have SECCOMP_ARCH_NATIVE,
            SECCOMP_ARCH_NATIVE_NR, SECCOMP_ARCH_NATIVE_NAME defined. If
            COMPAT is supported, have the SECCOMP_ARCH_COMPAT* defines too.

config SECCOMP
        prompt "Enable seccomp to safely execute untrusted bytecode"
        def_bool y
        depends on HAVE_ARCH_SECCOMP
        help
          This kernel feature is useful for number crunching applications
          that may need to handle untrusted bytecode during their
          execution. By using pipes or other transports made available
          to the process as file descriptors supporting the read/write
          syscalls, it's possible to isolate those applications in their
          own address space using seccomp. Once seccomp is enabled via
          prctl(PR_SET_SECCOMP) or the seccomp() syscall, it cannot be
          disabled and the task is only allowed to execute a few safe
          syscalls defined by each seccomp mode.

          If unsure, say Y.

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 SECCOMP_CACHE_DEBUG
        bool "Show seccomp filter cache status in /proc/pid/seccomp_cache"
        depends on SECCOMP_FILTER && !HAVE_SPARSE_SYSCALL_NR
        depends on PROC_FS
        help
          This enables the /proc/pid/seccomp_cache interface to monitor
          seccomp cache data. The file format is subject to change. Reading
          the file requires CAP_SYS_ADMIN.

          This option is for debugging only. Enabling presents the risk that
          an adversary may be able to infer the seccomp filter logic.

          If unsure, say N.

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.

          This feature requires gcc version 4.2 or above, or a distribution
          gcc with the feature backported ("-fstack-protector").

          On an x86 "defconfig" build, this feature adds canary checks to
          about 3% of all kernel functions, which increases kernel code size
          by about 0.3%.

config STACKPROTECTOR_STRONG
        bool "Strong Stack Protector"
        depends on STACKPROTECTOR
        depends on $(cc-option,-fstack-protector-strong)
        default y
        help
          Functions will have the stack-protector canary logic added in any
          of the following conditions:

          - local variable's address used as part of the right hand side of an
            assignment or function argument
          - local variable is an array (or union containing an array),
            regardless of array type or length
          - uses register local variables

          This feature requires gcc version 4.9 or above, or a distribution
          gcc with the feature backported ("-fstack-protector-strong").

          On an x86 "defconfig" build, this feature adds canary checks to
          about 20% of all kernel functions, which increases the kernel code
          size by about 2%.

config ARCH_SUPPORTS_SHADOW_CALL_STACK
        bool
        help
          An architecture should select this if it supports Clang's Shadow
          Call Stack and implements runtime support for shadow stack
          switching.

config SHADOW_CALL_STACK
        bool "Clang Shadow Call Stack"
        depends on CC_IS_CLANG && ARCH_SUPPORTS_SHADOW_CALL_STACK
        depends on DYNAMIC_FTRACE_WITH_REGS || !FUNCTION_GRAPH_TRACER
        help
          This option enables Clang's Shadow Call Stack, which uses a
          shadow stack to protect function return addresses from being
          overwritten by an attacker. More information can be found in
          Clang's documentation:

            https://clang.llvm.org/docs/ShadowCallStack.html

          Note that security guarantees in the kernel differ from the
          ones documented for user space. The kernel must store addresses
          of shadow stacks in memory, which means an attacker capable of
          reading and writing arbitrary memory may be able to locate them
          and hijack control flow by modifying the stacks.

config LTO
        bool
        help
          Selected if the kernel will be built using the compiler's LTO feature.

config LTO_CLANG
        bool
        select LTO
        help
          Selected if the kernel will be built using Clang's LTO feature.

config ARCH_SUPPORTS_LTO_CLANG
        bool
        help
          An architecture should select this option if it supports:
          - compiling with Clang,
          - compiling inline assembly with Clang's integrated assembler,
          - and linking with LLD.

config ARCH_SUPPORTS_LTO_CLANG_THIN
        bool
        help
          An architecture should select this option if it can support Clang's
          ThinLTO mode.

config HAS_LTO_CLANG
        def_bool y
        # Clang >= 11: https://github.com/ClangBuiltLinux/linux/issues/510
        depends on CC_IS_CLANG && CLANG_VERSION >= 110000 && LD_IS_LLD && AS_IS_LLVM
        depends on $(success,$(NM) --help | head -n 1 | grep -qi llvm)
        depends on $(success,$(AR) --help | head -n 1 | grep -qi llvm)
        depends on ARCH_SUPPORTS_LTO_CLANG
        depends on !FTRACE_MCOUNT_USE_RECORDMCOUNT
        depends on !KASAN || KASAN_HW_TAGS
        depends on !GCOV_KERNEL
        help
          The compiler and Kconfig options support building with Clang's
          LTO.

choice
        prompt "Link Time Optimization (LTO)"
        default LTO_NONE
        help
          This option enables Link Time Optimization (LTO), which allows the
          compiler to optimize binaries globally.

          If unsure, select LTO_NONE. Note that LTO is very resource-intensive
          so it's disabled by default.

config LTO_NONE
        bool "None"
        help
          Build the kernel normally, without Link Time Optimization (LTO).

config LTO_CLANG_FULL
        bool "Clang Full LTO (EXPERIMENTAL)"
        depends on HAS_LTO_CLANG
        depends on !COMPILE_TEST
        select LTO_CLANG
        help
          This option enables Clang's full Link Time Optimization (LTO), which
          allows the compiler to optimize the kernel globally. If you enable
          this option, the compiler generates LLVM bitcode instead of ELF
          object files, and the actual compilation from bitcode happens at
          the LTO link step, which may take several minutes depending on the
          kernel configuration. More information can be found from LLVM's
          documentation:

            https://llvm.org/docs/LinkTimeOptimization.html

          During link time, this option can use a large amount of RAM, and
          may take much longer than the ThinLTO option.

config LTO_CLANG_THIN
        bool "Clang ThinLTO (EXPERIMENTAL)"
        depends on HAS_LTO_CLANG && ARCH_SUPPORTS_LTO_CLANG_THIN
        select LTO_CLANG
        help
          This option enables Clang's ThinLTO, which allows for parallel
          optimization and faster incremental compiles compared to the
          CONFIG_LTO_CLANG_FULL option. More information can be found
          from Clang's documentation:

            https://clang.llvm.org/docs/ThinLTO.html

          If unsure, say Y.
endchoice

config ARCH_SUPPORTS_CFI_CLANG
        bool
        help
          An architecture should select this option if it can support Clang's
          Control-Flow Integrity (CFI) checking.

config CFI_CLANG
        bool "Use Clang's Control Flow Integrity (CFI)"
        depends on LTO_CLANG && ARCH_SUPPORTS_CFI_CLANG
        # Clang >= 12:
        # - https://bugs.llvm.org/show_bug.cgi?id=46258
        # - https://bugs.llvm.org/show_bug.cgi?id=47479
        depends on CLANG_VERSION >= 120000
        select KALLSYMS
        help
          This option enables Clang’s forward-edge Control Flow Integrity
          (CFI) checking, where the compiler injects a runtime check to each
          indirect function call to ensure the target is a valid function with
          the correct static type. This restricts possible call targets and
          makes it more difficult for an attacker to exploit bugs that allow
          the modification of stored function pointers. More information can be
          found from Clang's documentation:

            https://clang.llvm.org/docs/ControlFlowIntegrity.html

config CFI_CLANG_SHADOW
        bool "Use CFI shadow to speed up cross-module checks"
        default y
        depends on CFI_CLANG && MODULES
        help
          If you select this option, the kernel builds a fast look-up table of
          CFI check functions in loaded modules to reduce performance overhead.

          If unsure, say Y.

config CFI_PERMISSIVE
        bool "Use CFI in permissive mode"
        depends on CFI_CLANG
        help
          When selected, Control Flow Integrity (CFI) violations result in a
          warning instead of a kernel panic. This option should only be used
          for finding indirect call type mismatches during development.

          If unsure, say N.

config HAVE_ARCH_WITHIN_STACK_FRAMES
        bool
        help
          An architecture should select this if it can walk the kernel stack
          frames to determine if an object is part of either the arguments
          or local variables (i.e. that it excludes saved return addresses,
          and similar) by implementing an inline arch_within_stack_frames(),
          which is used by CONFIG_HARDENED_USERCOPY.

config HAVE_CONTEXT_TRACKING
        bool
        help
          Provide kernel/user boundaries probes necessary for subsystems
          that need it, such as userspace RCU extended quiescent state.
          Syscalls need to be wrapped inside user_exit()-user_enter(), either
          optimized behind static key or through the slow path using TIF_NOHZ
          flag. Exceptions handlers must be wrapped as well. Irqs are already
          protected inside rcu_irq_enter/rcu_irq_exit() but preemption or signal
          handling on irq exit still need to be protected.

config HAVE_CONTEXT_TRACKING_OFFSTACK
        bool
        help
          Architecture neither relies on exception_enter()/exception_exit()
          nor on schedule_user(). Also preempt_schedule_notrace() and
          preempt_schedule_irq() can't be called in a preemptible section
          while context tracking is CONTEXT_USER. This feature reflects a sane
          entry implementation where the following requirements are met on
          critical entry code, ie: before user_exit() or after user_enter():

          - Critical entry code isn't preemptible (or better yet:
            not interruptible).
          - No use of RCU read side critical sections, unless rcu_nmi_enter()
            got called.
          - No use of instrumentation, unless instrumentation_begin() got
            called.

config HAVE_TIF_NOHZ
        bool
        help
          Arch relies on TIF_NOHZ and syscall slow path to implement context
          tracking calls to user_enter()/user_exit().

config HAVE_VIRT_CPU_ACCOUNTING
        bool

config HAVE_VIRT_CPU_ACCOUNTING_IDLE
        bool
        help
          Architecture has its own way to account idle CPU time and therefore
          doesn't implement vtime_account_idle().

config ARCH_HAS_SCALED_CPUTIME
        bool

config HAVE_VIRT_CPU_ACCOUNTING_GEN
        bool
        default y if 64BIT
        help
          With VIRT_CPU_ACCOUNTING_GEN, cputime_t becomes 64-bit.
          Before enabling this option, arch code must be audited
          to ensure there are no races in concurrent read/write of
          cputime_t. For example, reading/writing 64-bit cputime_t on
          some 32-bit arches may require multiple accesses, so proper
          locking is needed to protect against concurrent accesses.

config HAVE_IRQ_TIME_ACCOUNTING
        bool
        help
          Archs need to ensure they use a high enough resolution clock to
          support irq time accounting and then call enable_sched_clock_irqtime().

config HAVE_MOVE_PUD
        bool
        help
          Architectures that select this are able to move page tables at the
          PUD level. If there are only 3 page table levels, the move effectively
          happens at the PGD level.

config HAVE_MOVE_PMD
        bool
        help
          Archs that select this are able to move page tables at the PMD level.

config HAVE_ARCH_TRANSPARENT_HUGEPAGE
        bool

config HAVE_ARCH_TRANSPARENT_HUGEPAGE_PUD
        bool

config HAVE_ARCH_HUGE_VMAP
        bool

#
#  Archs that select this would be capable of PMD-sized vmaps (i.e.,
#  arch_vmap_pmd_supported() returns true), and they must make no assumptions
#  that vmalloc memory is mapped with PAGE_SIZE ptes. The VM_NO_HUGE_VMAP flag
#  can be used to prohibit arch-specific allocations from using hugepages to
#  help with this (e.g., modules may require it).
#
config HAVE_ARCH_HUGE_VMALLOC
        depends on HAVE_ARCH_HUGE_VMAP
        bool

config ARCH_WANT_HUGE_PMD_SHARE
        bool

config HAVE_ARCH_SOFT_DIRTY
        bool

config HAVE_MOD_ARCH_SPECIFIC
        bool
        help
          The arch uses struct mod_arch_specific to store data.  Many arches
          just need a simple module loader without arch specific data - those
          should not enable this.

config MODULES_USE_ELF_RELA
        bool
        help
          Modules only use ELF RELA relocations.  Modules with ELF REL
          relocations will give an error.

config MODULES_USE_ELF_REL
        bool
        help
          Modules only use ELF REL relocations.  Modules with ELF RELA
          relocations will give an error.

config HAVE_IRQ_EXIT_ON_IRQ_STACK
        bool
        help
          Architecture doesn't only execute the irq handler on the irq stack
          but also irq_exit(). This way we can process softirqs on this irq
          stack instead of switching to a new one when we call __do_softirq()
          in the end of an hardirq.
          This spares a stack switch and improves cache usage on softirq
          processing.

config HAVE_SOFTIRQ_ON_OWN_STACK
        bool
        help
          Architecture provides a function to run __do_softirq() on a
          separate stack.

config PGTABLE_LEVELS
        int
        default 2

config ARCH_HAS_ELF_RANDOMIZE
        bool
        help
          An architecture supports choosing randomized locations for
          stack, mmap, brk, and ET_DYN. Defined functions:
          - arch_mmap_rnd()
          - arch_randomize_brk()

config HAVE_ARCH_MMAP_RND_BITS
        bool
        help
          An arch should select this symbol if it supports setting a variable
          number of bits for use in establishing the base address for mmap
          allocations, has MMU enabled and provides values for both:
          - ARCH_MMAP_RND_BITS_MIN
          - ARCH_MMAP_RND_BITS_MAX

config HAVE_EXIT_THREAD
        bool
        help
          An architecture implements exit_thread.

config ARCH_MMAP_RND_BITS_MIN
        int

config ARCH_MMAP_RND_BITS_MAX
        int

config ARCH_MMAP_RND_BITS_DEFAULT
        int

config ARCH_MMAP_RND_BITS
        int "Number of bits to use for ASLR of mmap base address" if EXPERT
        range ARCH_MMAP_RND_BITS_MIN ARCH_MMAP_RND_BITS_MAX
        default ARCH_MMAP_RND_BITS_DEFAULT if ARCH_MMAP_RND_BITS_DEFAULT
        default ARCH_MMAP_RND_BITS_MIN
        depends on HAVE_ARCH_MMAP_RND_BITS
        help
          This value can be used to select the number of bits to use to
          determine the random offset to the base address of vma regions
          resulting from mmap allocations. This value will be bounded
          by the architecture's minimum and maximum supported values.

          This value can be changed after boot using the
          /proc/sys/vm/mmap_rnd_bits tunable

config HAVE_ARCH_MMAP_RND_COMPAT_BITS
        bool
        help
          An arch should select this symbol if it supports running applications
          in compatibility mode, supports setting a variable number of bits for
          use in establishing the base address for mmap allocations, has MMU
          enabled and provides values for both:
          - ARCH_MMAP_RND_COMPAT_BITS_MIN
          - ARCH_MMAP_RND_COMPAT_BITS_MAX

config ARCH_MMAP_RND_COMPAT_BITS_MIN
        int

config ARCH_MMAP_RND_COMPAT_BITS_MAX
        int

config ARCH_MMAP_RND_COMPAT_BITS_DEFAULT
        int

config ARCH_MMAP_RND_COMPAT_BITS
        int "Number of bits to use for ASLR of mmap base address for compatible applications" if EXPERT
        range ARCH_MMAP_RND_COMPAT_BITS_MIN ARCH_MMAP_RND_COMPAT_BITS_MAX
        default ARCH_MMAP_RND_COMPAT_BITS_DEFAULT if ARCH_MMAP_RND_COMPAT_BITS_DEFAULT
        default ARCH_MMAP_RND_COMPAT_BITS_MIN
        depends on HAVE_ARCH_MMAP_RND_COMPAT_BITS
        help
          This value can be used to select the number of bits to use to
          determine the random offset to the base address of vma regions
          resulting from mmap allocations for compatible applications This
          value will be bounded by the architecture's minimum and maximum
          supported values.

          This value can be changed after boot using the
          /proc/sys/vm/mmap_rnd_compat_bits tunable

config HAVE_ARCH_COMPAT_MMAP_BASES
        bool
        help
          This allows 64bit applications to invoke 32-bit mmap() syscall
          and vice-versa 32-bit applications to call 64-bit mmap().
          Required for applications doing different bitness syscalls.

config PAGE_SIZE_LESS_THAN_64KB
        def_bool y
        depends on !ARM64_64K_PAGES
        depends on !IA64_PAGE_SIZE_64KB
        depends on !PAGE_SIZE_64KB
        depends on !PARISC_PAGE_SIZE_64KB
        depends on !PPC_64K_PAGES

        depends on !PPC_256K_PAGES
        depends on !PAGE_SIZE_256KB

# This allows to use a set of generic functions to determine mmap base
# address by giving priority to top-down scheme only if the process
# is not in legacy mode (compat task, unlimited stack size or
# sysctl_legacy_va_layout).
# Architecture that selects this option can provide its own version of:
# - STACK_RND_MASK
config ARCH_WANT_DEFAULT_TOPDOWN_MMAP_LAYOUT
        bool
        depends on MMU
        select ARCH_HAS_ELF_RANDOMIZE

config HAVE_STACK_VALIDATION
        bool
        help
          Architecture supports the 'objtool check' host tool command, which
          performs compile-time stack metadata validation.

config HAVE_RELIABLE_STACKTRACE
        bool
        help
          Architecture has either save_stack_trace_tsk_reliable() or
          arch_stack_walk_reliable() function which only returns a stack trace
          if it can guarantee the trace is reliable.

config HAVE_ARCH_HASH
        bool
        default n
        help
          If this is set, the architecture provides an <asm/hash.h>
          file which provides platform-specific implementations of some
          functions in <linux/hash.h> or fs/namei.c.

config HAVE_ARCH_NVRAM_OPS
        bool

config ISA_BUS_API
        def_bool ISA

#
# ABI hall of shame
#
config CLONE_BACKWARDS
        bool
        help
          Architecture has tls passed as the 4th argument of clone(2),
          not the 5th one.

config CLONE_BACKWARDS2
        bool
        help
          Architecture has the first two arguments of clone(2) swapped.

config CLONE_BACKWARDS3
        bool
        help
          Architecture has tls passed as the 3rd argument of clone(2),
          not the 5th one.

config ODD_RT_SIGACTION
        bool
        help
          Architecture has unusual rt_sigaction(2) arguments

config OLD_SIGSUSPEND
        bool
        help
          Architecture has old sigsuspend(2) syscall, of one-argument variety

config OLD_SIGSUSPEND3
        bool
        help
          Even weirder antique ABI - three-argument sigsuspend(2)

config OLD_SIGACTION
        bool
        help
          Architecture has old sigaction(2) syscall.  Nope, not the same
          as OLD_SIGSUSPEND | OLD_SIGSUSPEND3 - alpha has sigsuspend(2),
          but fairly different variant of sigaction(2), thanks to OSF/1
          compatibility...

config COMPAT_OLD_SIGACTION
        bool

config COMPAT_32BIT_TIME
        bool "Provide system calls for 32-bit time_t"
        default !64BIT || COMPAT
        help
          This enables 32 bit time_t support in addition to 64 bit time_t support.
          This is relevant on all 32-bit architectures, and 64-bit architectures
          as part of compat syscall handling.

config ARCH_NO_PREEMPT
        bool

config ARCH_EPHEMERAL_INODES
        def_bool n
        help
          An arch should select this symbol if it doesn't keep track of inode
          instances on its own, but instead relies on something else (e.g. the
          host kernel for an UML kernel).

config ARCH_SUPPORTS_RT
        bool

config CPU_NO_EFFICIENT_FFS
        def_bool n

config HAVE_ARCH_VMAP_STACK
        def_bool n
        help
          An arch should select this symbol if it can support kernel stacks
          in vmalloc space.  This means:

          - vmalloc space must be large enough to hold many kernel stacks.
            This may rule out many 32-bit architectures.

          - Stacks in vmalloc space need to work reliably.  For example, if
            vmap page tables are created on demand, either this mechanism
            needs to work while the stack points to a virtual address with
            unpopulated page tables or arch code (switch_to() and switch_mm(),
            most likely) needs to ensure that the stack's page table entries
            are populated before running on a possibly unpopulated stack.

          - If the stack overflows into a guard page, something reasonable
            should happen.  The definition of "reasonable" is flexible, but
            instantly rebooting without logging anything would be unfriendly.

config VMAP_STACK
        default y
        bool "Use a virtually-mapped stack"
        depends on HAVE_ARCH_VMAP_STACK
        depends on !KASAN || KASAN_HW_TAGS || KASAN_VMALLOC
        help
          Enable this if you want the use virtually-mapped kernel stacks
          with guard pages.  This causes kernel stack overflows to be
          caught immediately rather than causing difficult-to-diagnose
          corruption.

          To use this with software KASAN modes, the architecture must support
          backing virtual mappings with real shadow memory, and KASAN_VMALLOC
          must be enabled.

config HAVE_ARCH_RANDOMIZE_KSTACK_OFFSET
        def_bool n
        help
          An arch should select this symbol if it can support kernel stack
          offset randomization with calls to add_random_kstack_offset()
          during syscall entry and choose_random_kstack_offset() during
          syscall exit. Careful removal of -fstack-protector-strong and
          -fstack-protector should also be applied to the entry code and
          closely examined, as the artificial stack bump looks like an array
          to the compiler, so it will attempt to add canary checks regardless
          of the static branch state.

config RANDOMIZE_KSTACK_OFFSET_DEFAULT
        bool "Randomize kernel stack offset on syscall entry"
        depends on HAVE_ARCH_RANDOMIZE_KSTACK_OFFSET
        help
          The kernel stack offset can be randomized (after pt_regs) by
          roughly 5 bits of entropy, frustrating memory corruption
          attacks that depend on stack address determinism or
          cross-syscall address exposures. This feature is controlled
          by kernel boot param "randomize_kstack_offset=on/off", and this
          config chooses the default boot state.

config ARCH_OPTIONAL_KERNEL_RWX
        def_bool n

config ARCH_OPTIONAL_KERNEL_RWX_DEFAULT
        def_bool n

config ARCH_HAS_STRICT_KERNEL_RWX
        def_bool n

config STRICT_KERNEL_RWX
        bool "Make kernel text and rodata read-only" if ARCH_OPTIONAL_KERNEL_RWX
        depends on ARCH_HAS_STRICT_KERNEL_RWX
        default !ARCH_OPTIONAL_KERNEL_RWX || ARCH_OPTIONAL_KERNEL_RWX_DEFAULT
        help
          If this is set, kernel text and rodata memory will be made read-only,
          and non-text memory will be made non-executable. This provides
          protection against certain security exploits (e.g. executing the heap
          or modifying text)

          These features are considered standard security practice these days.
          You should say Y here in almost all cases.

config ARCH_HAS_STRICT_MODULE_RWX
        def_bool n

config STRICT_MODULE_RWX
        bool "Set loadable kernel module data as NX and text as RO" if ARCH_OPTIONAL_KERNEL_RWX
        depends on ARCH_HAS_STRICT_MODULE_RWX && MODULES
        default !ARCH_OPTIONAL_KERNEL_RWX || ARCH_OPTIONAL_KERNEL_RWX_DEFAULT
        help
          If this is set, module text and rodata memory will be made read-only,
          and non-text memory will be made non-executable. This provides
          protection against certain security exploits (e.g. writing to text)

# select if the architecture provides an asm/dma-direct.h header
config ARCH_HAS_PHYS_TO_DMA
        bool

config HAVE_ARCH_COMPILER_H
        bool
        help
          An architecture can select this if it provides an
          asm/compiler.h header that should be included after
          linux/compiler-*.h in order to override macro definitions that those
          headers generally provide.

config HAVE_ARCH_PREL32_RELOCATIONS
        bool
        help
          May be selected by an architecture if it supports place-relative
          32-bit relocations, both in the toolchain and in the module loader,
          in which case relative references can be used in special sections
          for PCI fixup, initcalls etc which are only half the size on 64 bit
          architectures, and don't require runtime relocation on relocatable
          kernels.

config ARCH_USE_MEMREMAP_PROT
        bool

config LOCK_EVENT_COUNTS
        bool "Locking event counts collection"
        depends on DEBUG_FS
        help
          Enable light-weight counting of various locking related events
          in the system with minimal performance impact. This reduces
          the chance of application behavior change because of timing
          differences. The counts are reported via debugfs.

# Select if the architecture has support for applying RELR relocations.
config ARCH_HAS_RELR
        bool

config RELR
        bool "Use RELR relocation packing"
        depends on ARCH_HAS_RELR && TOOLS_SUPPORT_RELR
        default y
        help
          Store the kernel's dynamic relocations in the RELR relocation packing
          format. Requires a compatible linker (LLD supports this feature), as
          well as compatible NM and OBJCOPY utilities (llvm-nm and llvm-objcopy
          are compatible).

config ARCH_HAS_MEM_ENCRYPT
        bool

config ARCH_HAS_CC_PLATFORM
        bool

config HAVE_SPARSE_SYSCALL_NR
       bool
       help
          An architecture should select this if its syscall numbering is sparse
          to save space. For example, MIPS architecture has a syscall array with
          entries at 4000, 5000 and 6000 locations. This option turns on syscall
          related optimizations for a given architecture.

config ARCH_HAS_VDSO_DATA
        bool

config HAVE_STATIC_CALL
        bool

config HAVE_STATIC_CALL_INLINE
        bool
        depends on HAVE_STATIC_CALL

config HAVE_PREEMPT_DYNAMIC
        bool
        depends on HAVE_STATIC_CALL
        depends on GENERIC_ENTRY
        help
           Select this if the architecture support boot time preempt setting
           on top of static calls. It is strongly advised to support inline
           static call to avoid any overhead.

config ARCH_WANT_LD_ORPHAN_WARN
        bool
        help
          An arch should select this symbol once all linker sections are explicitly
          included, size-asserted, or discarded in the linker scripts. This is
          important because we never want expected sections to be placed heuristically
          by the linker, since the locations of such sections can change between linker
          versions.

config HAVE_ARCH_PFN_VALID
        bool

config ARCH_SUPPORTS_DEBUG_PAGEALLOC
        bool

config ARCH_SPLIT_ARG64
        bool
        help
           If a 32-bit architecture requires 64-bit arguments to be split into
           pairs of 32-bit arguments, select this option.

config ARCH_HAS_ELFCORE_COMPAT
        bool

config ARCH_HAS_PARANOID_L1D_FLUSH
        bool

config DYNAMIC_SIGFRAME
        bool

source "kernel/gcov/Kconfig"

source "scripts/gcc-plugins/Kconfig"

endmenu