arm64: Add skeleton to harden the branch predictor against aliasing attacks

[android-x86/kernel.git] / arch / arm64 / Kconfig

config ARM64
        def_bool y
        select ACPI_CCA_REQUIRED if ACPI
        select ACPI_GENERIC_GSI if ACPI
        select ACPI_REDUCED_HARDWARE_ONLY if ACPI
        select ACPI_MCFG if ACPI
        select ACPI_SPCR_TABLE if ACPI
        select ARCH_CLOCKSOURCE_DATA
        select ARCH_HAS_DEVMEM_IS_ALLOWED
        select ARCH_HAS_ACPI_TABLE_UPGRADE if ACPI
        select ARCH_HAS_ELF_RANDOMIZE
        select ARCH_HAS_GCOV_PROFILE_ALL
        select ARCH_HAS_GIGANTIC_PAGE
        select ARCH_HAS_KCOV
        select ARCH_HAS_SG_CHAIN
        select ARCH_HAS_TICK_BROADCAST if GENERIC_CLOCKEVENTS_BROADCAST
        select ARCH_USE_CMPXCHG_LOCKREF
        select ARCH_SUPPORTS_ATOMIC_RMW
        select ARCH_SUPPORTS_NUMA_BALANCING
        select ARCH_WANT_COMPAT_IPC_PARSE_VERSION
        select ARCH_WANT_FRAME_POINTERS
        select ARCH_HAS_UBSAN_SANITIZE_ALL
        select ARM_AMBA
        select ARM_ARCH_TIMER
        select ARM_GIC
        select AUDIT_ARCH_COMPAT_GENERIC
        select ARM_GIC_V2M if PCI
        select ARM_GIC_V3
        select ARM_GIC_V3_ITS if PCI
        select ARM_PSCI_FW
        select BUILDTIME_EXTABLE_SORT
        select CLONE_BACKWARDS
        select COMMON_CLK
        select CPU_PM if (SUSPEND || CPU_IDLE)
        select DCACHE_WORD_ACCESS
        select EDAC_SUPPORT
        select FRAME_POINTER
        select GENERIC_ALLOCATOR
        select GENERIC_CLOCKEVENTS
        select GENERIC_CLOCKEVENTS_BROADCAST
        select GENERIC_CPU_AUTOPROBE
        select GENERIC_EARLY_IOREMAP
        select GENERIC_IDLE_POLL_SETUP
        select GENERIC_IRQ_PROBE
        select GENERIC_IRQ_SHOW
        select GENERIC_IRQ_SHOW_LEVEL
        select GENERIC_PCI_IOMAP
        select GENERIC_SCHED_CLOCK
        select GENERIC_SMP_IDLE_THREAD
        select GENERIC_STRNCPY_FROM_USER
        select GENERIC_STRNLEN_USER
        select GENERIC_TIME_VSYSCALL
        select HANDLE_DOMAIN_IRQ
        select HARDIRQS_SW_RESEND
        select HAVE_ALIGNED_STRUCT_PAGE if SLUB
        select HAVE_ARCH_AUDITSYSCALL
        select HAVE_ARCH_BITREVERSE
        select HAVE_ARCH_HARDENED_USERCOPY
        select HAVE_ARCH_HUGE_VMAP
        select HAVE_ARCH_JUMP_LABEL
        select HAVE_ARCH_KASAN if SPARSEMEM_VMEMMAP && !(ARM64_16K_PAGES && ARM64_VA_BITS_48)
        select HAVE_ARCH_KGDB
        select HAVE_ARCH_MMAP_RND_BITS
        select HAVE_ARCH_MMAP_RND_COMPAT_BITS if COMPAT
        select HAVE_ARCH_SECCOMP_FILTER
        select HAVE_ARCH_TRACEHOOK
        select HAVE_ARCH_TRANSPARENT_HUGEPAGE
        select HAVE_ARM_SMCCC
        select HAVE_EBPF_JIT
        select HAVE_C_RECORDMCOUNT
        select HAVE_CC_STACKPROTECTOR
        select HAVE_CMPXCHG_DOUBLE
        select HAVE_CMPXCHG_LOCAL
        select HAVE_CONTEXT_TRACKING
        select HAVE_DEBUG_BUGVERBOSE
        select HAVE_DEBUG_KMEMLEAK
        select HAVE_DMA_API_DEBUG
        select HAVE_DMA_CONTIGUOUS
        select HAVE_DYNAMIC_FTRACE
        select HAVE_EFFICIENT_UNALIGNED_ACCESS
        select HAVE_FTRACE_MCOUNT_RECORD
        select HAVE_FUNCTION_TRACER
        select HAVE_FUNCTION_GRAPH_TRACER
        select HAVE_GCC_PLUGINS
        select HAVE_GENERIC_DMA_COHERENT
        select HAVE_HW_BREAKPOINT if PERF_EVENTS
        select HAVE_IRQ_TIME_ACCOUNTING
        select HAVE_MEMBLOCK
        select HAVE_MEMBLOCK_NODE_MAP if NUMA
        select HAVE_PATA_PLATFORM
        select HAVE_PERF_EVENTS
        select HAVE_PERF_REGS
        select HAVE_PERF_USER_STACK_DUMP
        select HAVE_REGS_AND_STACK_ACCESS_API
        select HAVE_RCU_TABLE_FREE
        select HAVE_SYSCALL_TRACEPOINTS
        select HAVE_KPROBES
        select HAVE_KRETPROBES if HAVE_KPROBES
        select IOMMU_DMA if IOMMU_SUPPORT
        select IRQ_DOMAIN
        select IRQ_FORCED_THREADING
        select MODULES_USE_ELF_RELA
        select NO_BOOTMEM
        select OF
        select OF_EARLY_FLATTREE
        select OF_RESERVED_MEM
        select PCI_ECAM if ACPI
        select POWER_RESET
        select POWER_SUPPLY
        select SPARSE_IRQ
        select SYSCTL_EXCEPTION_TRACE
        help
          ARM 64-bit (AArch64) Linux support.

config 64BIT
        def_bool y

config ARCH_PHYS_ADDR_T_64BIT
        def_bool y

config MMU
        def_bool y

config DEBUG_RODATA
        def_bool y

config ARM64_PAGE_SHIFT
        int
        default 16 if ARM64_64K_PAGES
        default 14 if ARM64_16K_PAGES
        default 12

config ARM64_CONT_SHIFT
        int
        default 5 if ARM64_64K_PAGES
        default 7 if ARM64_16K_PAGES
        default 4

config ARCH_MMAP_RND_BITS_MIN
       default 14 if ARM64_64K_PAGES
       default 16 if ARM64_16K_PAGES
       default 18

# max bits determined by the following formula:
#  VA_BITS - PAGE_SHIFT - 3
config ARCH_MMAP_RND_BITS_MAX
       default 19 if ARM64_VA_BITS=36
       default 24 if ARM64_VA_BITS=39
       default 27 if ARM64_VA_BITS=42
       default 30 if ARM64_VA_BITS=47
       default 29 if ARM64_VA_BITS=48 && ARM64_64K_PAGES
       default 31 if ARM64_VA_BITS=48 && ARM64_16K_PAGES
       default 33 if ARM64_VA_BITS=48
       default 14 if ARM64_64K_PAGES
       default 16 if ARM64_16K_PAGES
       default 18

config ARCH_MMAP_RND_COMPAT_BITS_MIN
       default 7 if ARM64_64K_PAGES
       default 9 if ARM64_16K_PAGES
       default 11

config ARCH_MMAP_RND_COMPAT_BITS_MAX
       default 16

config NO_IOPORT_MAP
        def_bool y if !PCI

config STACKTRACE_SUPPORT
        def_bool y

config ILLEGAL_POINTER_VALUE
        hex
        default 0xdead000000000000

config LOCKDEP_SUPPORT
        def_bool y

config TRACE_IRQFLAGS_SUPPORT
        def_bool y

config RWSEM_XCHGADD_ALGORITHM
        def_bool y

config GENERIC_BUG
        def_bool y
        depends on BUG

config GENERIC_BUG_RELATIVE_POINTERS
        def_bool y
        depends on GENERIC_BUG

config GENERIC_HWEIGHT
        def_bool y

config GENERIC_CSUM
        def_bool y

config GENERIC_CALIBRATE_DELAY
        def_bool y

config ZONE_DMA
        def_bool y

config HAVE_GENERIC_RCU_GUP
        def_bool y

config ARCH_DMA_ADDR_T_64BIT
        def_bool y

config NEED_DMA_MAP_STATE
        def_bool y

config NEED_SG_DMA_LENGTH
        def_bool y

config SMP
        def_bool y

config SWIOTLB
        def_bool y

config IOMMU_HELPER
        def_bool SWIOTLB

config KERNEL_MODE_NEON
        def_bool y

config FIX_EARLYCON_MEM
        def_bool y

config PGTABLE_LEVELS
        int
        default 2 if ARM64_16K_PAGES && ARM64_VA_BITS_36
        default 2 if ARM64_64K_PAGES && ARM64_VA_BITS_42
        default 3 if ARM64_64K_PAGES && ARM64_VA_BITS_48
        default 3 if ARM64_4K_PAGES && ARM64_VA_BITS_39
        default 3 if ARM64_16K_PAGES && ARM64_VA_BITS_47
        default 4 if !ARM64_64K_PAGES && ARM64_VA_BITS_48

source "init/Kconfig"

source "kernel/Kconfig.freezer"

source "arch/arm64/Kconfig.platforms"

menu "Bus support"

config PCI
        bool "PCI support"
        help
          This feature enables support for PCI bus system. If you say Y
          here, the kernel will include drivers and infrastructure code
          to support PCI bus devices.

config PCI_DOMAINS
        def_bool PCI

config PCI_DOMAINS_GENERIC
        def_bool PCI

config PCI_SYSCALL
        def_bool PCI

source "drivers/pci/Kconfig"

endmenu

menu "Kernel Features"

menu "ARM errata workarounds via the alternatives framework"

config ARM64_ERRATUM_826319
        bool "Cortex-A53: 826319: System might deadlock if a write cannot complete until read data is accepted"
        default y
        help
          This option adds an alternative code sequence to work around ARM
          erratum 826319 on Cortex-A53 parts up to r0p2 with an AMBA 4 ACE or
          AXI master interface and an L2 cache.

          If a Cortex-A53 uses an AMBA AXI4 ACE interface to other processors
          and is unable to accept a certain write via this interface, it will
          not progress on read data presented on the read data channel and the
          system can deadlock.

          The workaround promotes data cache clean instructions to
          data cache clean-and-invalidate.
          Please note that this does not necessarily enable the workaround,
          as it depends on the alternative framework, which will only patch
          the kernel if an affected CPU is detected.

          If unsure, say Y.

config ARM64_ERRATUM_827319
        bool "Cortex-A53: 827319: Data cache clean instructions might cause overlapping transactions to the interconnect"
        default y
        help
          This option adds an alternative code sequence to work around ARM
          erratum 827319 on Cortex-A53 parts up to r0p2 with an AMBA 5 CHI
          master interface and an L2 cache.

          Under certain conditions this erratum can cause a clean line eviction
          to occur at the same time as another transaction to the same address
          on the AMBA 5 CHI interface, which can cause data corruption if the
          interconnect reorders the two transactions.

          The workaround promotes data cache clean instructions to
          data cache clean-and-invalidate.
          Please note that this does not necessarily enable the workaround,
          as it depends on the alternative framework, which will only patch
          the kernel if an affected CPU is detected.

          If unsure, say Y.

config ARM64_ERRATUM_824069
        bool "Cortex-A53: 824069: Cache line might not be marked as clean after a CleanShared snoop"
        default y
        help
          This option adds an alternative code sequence to work around ARM
          erratum 824069 on Cortex-A53 parts up to r0p2 when it is connected
          to a coherent interconnect.

          If a Cortex-A53 processor is executing a store or prefetch for
          write instruction at the same time as a processor in another
          cluster is executing a cache maintenance operation to the same
          address, then this erratum might cause a clean cache line to be
          incorrectly marked as dirty.

          The workaround promotes data cache clean instructions to
          data cache clean-and-invalidate.
          Please note that this option does not necessarily enable the
          workaround, as it depends on the alternative framework, which will
          only patch the kernel if an affected CPU is detected.

          If unsure, say Y.

config ARM64_ERRATUM_819472
        bool "Cortex-A53: 819472: Store exclusive instructions might cause data corruption"
        default y
        help
          This option adds an alternative code sequence to work around ARM
          erratum 819472 on Cortex-A53 parts up to r0p1 with an L2 cache
          present when it is connected to a coherent interconnect.

          If the processor is executing a load and store exclusive sequence at
          the same time as a processor in another cluster is executing a cache
          maintenance operation to the same address, then this erratum might
          cause data corruption.

          The workaround promotes data cache clean instructions to
          data cache clean-and-invalidate.
          Please note that this does not necessarily enable the workaround,
          as it depends on the alternative framework, which will only patch
          the kernel if an affected CPU is detected.

          If unsure, say Y.

config ARM64_ERRATUM_832075
        bool "Cortex-A57: 832075: possible deadlock on mixing exclusive memory accesses with device loads"
        default y
        help
          This option adds an alternative code sequence to work around ARM
          erratum 832075 on Cortex-A57 parts up to r1p2.

          Affected Cortex-A57 parts might deadlock when exclusive load/store
          instructions to Write-Back memory are mixed with Device loads.

          The workaround is to promote device loads to use Load-Acquire
          semantics.
          Please note that this does not necessarily enable the workaround,
          as it depends on the alternative framework, which will only patch
          the kernel if an affected CPU is detected.

          If unsure, say Y.

config ARM64_ERRATUM_834220
        bool "Cortex-A57: 834220: Stage 2 translation fault might be incorrectly reported in presence of a Stage 1 fault"
        depends on KVM
        default y
        help
          This option adds an alternative code sequence to work around ARM
          erratum 834220 on Cortex-A57 parts up to r1p2.

          Affected Cortex-A57 parts might report a Stage 2 translation
          fault as the result of a Stage 1 fault for load crossing a
          page boundary when there is a permission or device memory
          alignment fault at Stage 1 and a translation fault at Stage 2.

          The workaround is to verify that the Stage 1 translation
          doesn't generate a fault before handling the Stage 2 fault.
          Please note that this does not necessarily enable the workaround,
          as it depends on the alternative framework, which will only patch
          the kernel if an affected CPU is detected.

          If unsure, say Y.

config ARM64_ERRATUM_845719
        bool "Cortex-A53: 845719: a load might read incorrect data"
        depends on COMPAT
        default y
        help
          This option adds an alternative code sequence to work around ARM
          erratum 845719 on Cortex-A53 parts up to r0p4.

          When running a compat (AArch32) userspace on an affected Cortex-A53
          part, a load at EL0 from a virtual address that matches the bottom 32
          bits of the virtual address used by a recent load at (AArch64) EL1
          might return incorrect data.

          The workaround is to write the contextidr_el1 register on exception
          return to a 32-bit task.
          Please note that this does not necessarily enable the workaround,
          as it depends on the alternative framework, which will only patch
          the kernel if an affected CPU is detected.

          If unsure, say Y.

config ARM64_ERRATUM_843419
        bool "Cortex-A53: 843419: A load or store might access an incorrect address"
        default y
        select ARM64_MODULE_CMODEL_LARGE if MODULES
        help
          This option links the kernel with '--fix-cortex-a53-843419' and
          builds modules using the large memory model in order to avoid the use
          of the ADRP instruction, which can cause a subsequent memory access
          to use an incorrect address on Cortex-A53 parts up to r0p4.

          If unsure, say Y.

config CAVIUM_ERRATUM_22375
        bool "Cavium erratum 22375, 24313"
        default y
        help
          Enable workaround for erratum 22375, 24313.

          This implements two gicv3-its errata workarounds for ThunderX. Both
          with small impact affecting only ITS table allocation.

            erratum 22375: only alloc 8MB table size
            erratum 24313: ignore memory access type

          The fixes are in ITS initialization and basically ignore memory access
          type and table size provided by the TYPER and BASER registers.

          If unsure, say Y.

config CAVIUM_ERRATUM_23144
        bool "Cavium erratum 23144: ITS SYNC hang on dual socket system"
        depends on NUMA
        default y
        help
          ITS SYNC command hang for cross node io and collections/cpu mapping.

          If unsure, say Y.

config CAVIUM_ERRATUM_23154
        bool "Cavium erratum 23154: Access to ICC_IAR1_EL1 is not sync'ed"
        default y
        help
          The gicv3 of ThunderX requires a modified version for
          reading the IAR status to ensure data synchronization
          (access to icc_iar1_el1 is not sync'ed before and after).

          If unsure, say Y.

config CAVIUM_ERRATUM_27456
        bool "Cavium erratum 27456: Broadcast TLBI instructions may cause icache corruption"
        default y
        help
          On ThunderX T88 pass 1.x through 2.1 parts, broadcast TLBI
          instructions may cause the icache to become corrupted if it
          contains data for a non-current ASID.  The fix is to
          invalidate the icache when changing the mm context.

          If unsure, say Y.

config QCOM_QDF2400_ERRATUM_0065
        bool "QDF2400 E0065: Incorrect GITS_TYPER.ITT_Entry_size"
        default y
        help
          On Qualcomm Datacenter Technologies QDF2400 SoC, ITS hardware reports
          ITE size incorrectly. The GITS_TYPER.ITT_Entry_size field should have
          been indicated as 16Bytes (0xf), not 8Bytes (0x7).

          If unsure, say Y.

endmenu


choice
        prompt "Page size"
        default ARM64_4K_PAGES
        help
          Page size (translation granule) configuration.

config ARM64_4K_PAGES
        bool "4KB"
        help
          This feature enables 4KB pages support.

config ARM64_16K_PAGES
        bool "16KB"
        help
          The system will use 16KB pages support. AArch32 emulation
          requires applications compiled with 16K (or a multiple of 16K)
          aligned segments.

config ARM64_64K_PAGES
        bool "64KB"
        help
          This feature enables 64KB pages support (4KB by default)
          allowing only two levels of page tables and faster TLB
          look-up. AArch32 emulation requires applications compiled
          with 64K aligned segments.

endchoice

choice
        prompt "Virtual address space size"
        default ARM64_VA_BITS_39 if ARM64_4K_PAGES
        default ARM64_VA_BITS_47 if ARM64_16K_PAGES
        default ARM64_VA_BITS_42 if ARM64_64K_PAGES
        help
          Allows choosing one of multiple possible virtual address
          space sizes. The level of translation table is determined by
          a combination of page size and virtual address space size.

config ARM64_VA_BITS_36
        bool "36-bit" if EXPERT
        depends on ARM64_16K_PAGES

config ARM64_VA_BITS_39
        bool "39-bit"
        depends on ARM64_4K_PAGES

config ARM64_VA_BITS_42
        bool "42-bit"
        depends on ARM64_64K_PAGES

config ARM64_VA_BITS_47
        bool "47-bit"
        depends on ARM64_16K_PAGES

config ARM64_VA_BITS_48
        bool "48-bit"

endchoice

config ARM64_VA_BITS
        int
        default 36 if ARM64_VA_BITS_36
        default 39 if ARM64_VA_BITS_39
        default 42 if ARM64_VA_BITS_42
        default 47 if ARM64_VA_BITS_47
        default 48 if ARM64_VA_BITS_48

config CPU_BIG_ENDIAN
       bool "Build big-endian kernel"
       help
         Say Y if you plan on running a kernel in big-endian mode.

config SCHED_MC
        bool "Multi-core scheduler support"
        help
          Multi-core scheduler support improves the CPU scheduler's decision
          making when dealing with multi-core CPU chips at a cost of slightly
          increased overhead in some places. If unsure say N here.

config SCHED_SMT
        bool "SMT scheduler support"
        help
          Improves the CPU scheduler's decision making when dealing with
          MultiThreading at a cost of slightly increased overhead in some
          places. If unsure say N here.

config NR_CPUS
        int "Maximum number of CPUs (2-4096)"
        range 2 4096
        # These have to remain sorted largest to smallest
        default "64"

config HOTPLUG_CPU
        bool "Support for hot-pluggable CPUs"
        select GENERIC_IRQ_MIGRATION
        help
          Say Y here to experiment with turning CPUs off and on.  CPUs
          can be controlled through /sys/devices/system/cpu.

# Common NUMA Features
config NUMA
        bool "Numa Memory Allocation and Scheduler Support"
        select ACPI_NUMA if ACPI
        select OF_NUMA
        help
          Enable NUMA (Non Uniform Memory Access) support.

          The kernel will try to allocate memory used by a CPU on the
          local memory of the CPU and add some more
          NUMA awareness to the kernel.

config NODES_SHIFT
        int "Maximum NUMA Nodes (as a power of 2)"
        range 1 10
        default "2"
        depends on NEED_MULTIPLE_NODES
        help
          Specify the maximum number of NUMA Nodes available on the target
          system.  Increases memory reserved to accommodate various tables.

config USE_PERCPU_NUMA_NODE_ID
        def_bool y
        depends on NUMA

config HAVE_SETUP_PER_CPU_AREA
        def_bool y
        depends on NUMA

config NEED_PER_CPU_EMBED_FIRST_CHUNK
        def_bool y
        depends on NUMA

source kernel/Kconfig.preempt
source kernel/Kconfig.hz

config ARCH_SUPPORTS_DEBUG_PAGEALLOC
        def_bool y

config ARCH_HAS_HOLES_MEMORYMODEL
        def_bool y if SPARSEMEM

config ARCH_SPARSEMEM_ENABLE
        def_bool y
        select SPARSEMEM_VMEMMAP_ENABLE

config ARCH_SPARSEMEM_DEFAULT
        def_bool ARCH_SPARSEMEM_ENABLE

config ARCH_SELECT_MEMORY_MODEL
        def_bool ARCH_SPARSEMEM_ENABLE

config HAVE_ARCH_PFN_VALID
        def_bool ARCH_HAS_HOLES_MEMORYMODEL || !SPARSEMEM

config HW_PERF_EVENTS
        def_bool y
        depends on ARM_PMU

config SYS_SUPPORTS_HUGETLBFS
        def_bool y

config ARCH_WANT_HUGE_PMD_SHARE
        def_bool y if ARM64_4K_PAGES || (ARM64_16K_PAGES && !ARM64_VA_BITS_36)

config ARCH_HAS_CACHE_LINE_SIZE
        def_bool y

source "mm/Kconfig"

config SECCOMP
        bool "Enable seccomp to safely compute untrusted bytecode"
        ---help---
          This kernel feature is useful for number crunching applications
          that may need to compute 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), it cannot be disabled
          and the task is only allowed to execute a few safe syscalls
          defined by each seccomp mode.

config PARAVIRT
        bool "Enable paravirtualization code"
        help
          This changes the kernel so it can modify itself when it is run
          under a hypervisor, potentially improving performance significantly
          over full virtualization.

config PARAVIRT_TIME_ACCOUNTING
        bool "Paravirtual steal time accounting"
        select PARAVIRT
        default n
        help
          Select this option to enable fine granularity task steal time
          accounting. Time spent executing other tasks in parallel with
          the current vCPU is discounted from the vCPU power. To account for
          that, there can be a small performance impact.

          If in doubt, say N here.

config KEXEC
        depends on PM_SLEEP_SMP
        select KEXEC_CORE
        bool "kexec system call"
        ---help---
          kexec is a system call that implements the ability to shutdown your
          current kernel, and to start another kernel.  It is like a reboot
          but it is independent of the system firmware.   And like a reboot
          you can start any kernel with it, not just Linux.

config XEN_DOM0
        def_bool y
        depends on XEN

config XEN
        bool "Xen guest support on ARM64"
        depends on ARM64 && OF
        select SWIOTLB_XEN
        select PARAVIRT
        help
          Say Y if you want to run Linux in a Virtual Machine on Xen on ARM64.

config FORCE_MAX_ZONEORDER
        int
        default "14" if (ARM64_64K_PAGES && TRANSPARENT_HUGEPAGE)
        default "12" if (ARM64_16K_PAGES && TRANSPARENT_HUGEPAGE)
        default "11"
        help
          The kernel memory allocator divides physically contiguous memory
          blocks into "zones", where each zone is a power of two number of
          pages.  This option selects the largest power of two that the kernel
          keeps in the memory allocator.  If you need to allocate very large
          blocks of physically contiguous memory, then you may need to
          increase this value.

          This config option is actually maximum order plus one. For example,
          a value of 11 means that the largest free memory block is 2^10 pages.

          We make sure that we can allocate upto a HugePage size for each configuration.
          Hence we have :
                MAX_ORDER = (PMD_SHIFT - PAGE_SHIFT) + 1 => PAGE_SHIFT - 2

          However for 4K, we choose a higher default value, 11 as opposed to 10, giving us
          4M allocations matching the default size used by generic code.

config UNMAP_KERNEL_AT_EL0
        bool "Unmap kernel when running in userspace (aka \"KAISER\")" if EXPERT
        default y
        help
          Speculation attacks against some high-performance processors can
          be used to bypass MMU permission checks and leak kernel data to
          userspace. This can be defended against by unmapping the kernel
          when running in userspace, mapping it back in on exception entry
          via a trampoline page in the vector table.

          If unsure, say Y.

config HARDEN_BRANCH_PREDICTOR
        bool "Harden the branch predictor against aliasing attacks" if EXPERT
        default y
        help
          Speculation attacks against some high-performance processors rely on
          being able to manipulate the branch predictor for a victim context by
          executing aliasing branches in the attacker context.  Such attacks
          can be partially mitigated against by clearing internal branch
          predictor state and limiting the prediction logic in some situations.

          This config option will take CPU-specific actions to harden the
          branch predictor against aliasing attacks and may rely on specific
          instruction sequences or control bits being set by the system
          firmware.

          If unsure, say Y.

menuconfig ARMV8_DEPRECATED
        bool "Emulate deprecated/obsolete ARMv8 instructions"
        depends on COMPAT
        help
          Legacy software support may require certain instructions
          that have been deprecated or obsoleted in the architecture.

          Enable this config to enable selective emulation of these
          features.

          If unsure, say Y

if ARMV8_DEPRECATED

config SWP_EMULATION
        bool "Emulate SWP/SWPB instructions"
        help
          ARMv8 obsoletes the use of A32 SWP/SWPB instructions such that
          they are always undefined. Say Y here to enable software
          emulation of these instructions for userspace using LDXR/STXR.

          In some older versions of glibc [<=2.8] SWP is used during futex
          trylock() operations with the assumption that the code will not
          be preempted. This invalid assumption may be more likely to fail
          with SWP emulation enabled, leading to deadlock of the user
          application.

          NOTE: when accessing uncached shared regions, LDXR/STXR rely
          on an external transaction monitoring block called a global
          monitor to maintain update atomicity. If your system does not
          implement a global monitor, this option can cause programs that
          perform SWP operations to uncached memory to deadlock.

          If unsure, say Y

config CP15_BARRIER_EMULATION
        bool "Emulate CP15 Barrier instructions"
        help
          The CP15 barrier instructions - CP15ISB, CP15DSB, and
          CP15DMB - are deprecated in ARMv8 (and ARMv7). It is
          strongly recommended to use the ISB, DSB, and DMB
          instructions instead.

          Say Y here to enable software emulation of these
          instructions for AArch32 userspace code. When this option is
          enabled, CP15 barrier usage is traced which can help
          identify software that needs updating.

          If unsure, say Y

config SETEND_EMULATION
        bool "Emulate SETEND instruction"
        help
          The SETEND instruction alters the data-endianness of the
          AArch32 EL0, and is deprecated in ARMv8.

          Say Y here to enable software emulation of the instruction
          for AArch32 userspace code.

          Note: All the cpus on the system must have mixed endian support at EL0
          for this feature to be enabled. If a new CPU - which doesn't support mixed
          endian - is hotplugged in after this feature has been enabled, there could
          be unexpected results in the applications.

          If unsure, say Y
endif

menu "ARMv8.1 architectural features"

config ARM64_HW_AFDBM
        bool "Support for hardware updates of the Access and Dirty page flags"
        default y
        help
          The ARMv8.1 architecture extensions introduce support for
          hardware updates of the access and dirty information in page
          table entries. When enabled in TCR_EL1 (HA and HD bits) on
          capable processors, accesses to pages with PTE_AF cleared will
          set this bit instead of raising an access flag fault.
          Similarly, writes to read-only pages with the DBM bit set will
          clear the read-only bit (AP[2]) instead of raising a
          permission fault.

          Kernels built with this configuration option enabled continue
          to work on pre-ARMv8.1 hardware and the performance impact is
          minimal. If unsure, say Y.

config ARM64_PAN
        bool "Enable support for Privileged Access Never (PAN)"
        default y
        help
         Privileged Access Never (PAN; part of the ARMv8.1 Extensions)
         prevents the kernel or hypervisor from accessing user-space (EL0)
         memory directly.

         Choosing this option will cause any unprotected (not using
         copy_to_user et al) memory access to fail with a permission fault.

         The feature is detected at runtime, and will remain as a 'nop'
         instruction if the cpu does not implement the feature.

config ARM64_LSE_ATOMICS
        bool "Atomic instructions"
        help
          As part of the Large System Extensions, ARMv8.1 introduces new
          atomic instructions that are designed specifically to scale in
          very large systems.

          Say Y here to make use of these instructions for the in-kernel
          atomic routines. This incurs a small overhead on CPUs that do
          not support these instructions and requires the kernel to be
          built with binutils >= 2.25.

config ARM64_VHE
        bool "Enable support for Virtualization Host Extensions (VHE)"
        default y
        help
          Virtualization Host Extensions (VHE) allow the kernel to run
          directly at EL2 (instead of EL1) on processors that support
          it. This leads to better performance for KVM, as they reduce
          the cost of the world switch.

          Selecting this option allows the VHE feature to be detected
          at runtime, and does not affect processors that do not
          implement this feature.

endmenu

menu "ARMv8.2 architectural features"

config ARM64_UAO
        bool "Enable support for User Access Override (UAO)"
        default y
        help
          User Access Override (UAO; part of the ARMv8.2 Extensions)
          causes the 'unprivileged' variant of the load/store instructions to
          be overriden to be privileged.

          This option changes get_user() and friends to use the 'unprivileged'
          variant of the load/store instructions. This ensures that user-space
          really did have access to the supplied memory. When addr_limit is
          set to kernel memory the UAO bit will be set, allowing privileged
          access to kernel memory.

          Choosing this option will cause copy_to_user() et al to use user-space
          memory permissions.

          The feature is detected at runtime, the kernel will use the
          regular load/store instructions if the cpu does not implement the
          feature.

endmenu

config ARM64_MODULE_CMODEL_LARGE
        bool

config ARM64_MODULE_PLTS
        bool
        select ARM64_MODULE_CMODEL_LARGE
        select HAVE_MOD_ARCH_SPECIFIC

config RELOCATABLE
        bool
        help
          This builds the kernel as a Position Independent Executable (PIE),
          which retains all relocation metadata required to relocate the
          kernel binary at runtime to a different virtual address than the
          address it was linked at.
          Since AArch64 uses the RELA relocation format, this requires a
          relocation pass at runtime even if the kernel is loaded at the
          same address it was linked at.

config RANDOMIZE_BASE
        bool "Randomize the address of the kernel image"
        select ARM64_MODULE_PLTS if MODULES
        select RELOCATABLE
        help
          Randomizes the virtual address at which the kernel image is
          loaded, as a security feature that deters exploit attempts
          relying on knowledge of the location of kernel internals.

          It is the bootloader's job to provide entropy, by passing a
          random u64 value in /chosen/kaslr-seed at kernel entry.

          When booting via the UEFI stub, it will invoke the firmware's
          EFI_RNG_PROTOCOL implementation (if available) to supply entropy
          to the kernel proper. In addition, it will randomise the physical
          location of the kernel Image as well.

          If unsure, say N.

config RANDOMIZE_MODULE_REGION_FULL
        bool "Randomize the module region independently from the core kernel"
        depends on RANDOMIZE_BASE && !DYNAMIC_FTRACE
        default y
        help
          Randomizes the location of the module region without considering the
          location of the core kernel. This way, it is impossible for modules
          to leak information about the location of core kernel data structures
          but it does imply that function calls between modules and the core
          kernel will need to be resolved via veneers in the module PLT.

          When this option is not set, the module region will be randomized over
          a limited range that contains the [_stext, _etext] interval of the
          core kernel, so branch relocations are always in range.

endmenu

menu "Boot options"

config ARM64_ACPI_PARKING_PROTOCOL
        bool "Enable support for the ARM64 ACPI parking protocol"
        depends on ACPI
        help
          Enable support for the ARM64 ACPI parking protocol. If disabled
          the kernel will not allow booting through the ARM64 ACPI parking
          protocol even if the corresponding data is present in the ACPI
          MADT table.

config CMDLINE
        string "Default kernel command string"
        default ""
        help
          Provide a set of default command-line options at build time by
          entering them here. As a minimum, you should specify the the
          root device (e.g. root=/dev/nfs).

config CMDLINE_FORCE
        bool "Always use the default kernel command string"
        help
          Always use the default kernel command string, even if the boot
          loader passes other arguments to the kernel.
          This is useful if you cannot or don't want to change the
          command-line options your boot loader passes to the kernel.

config EFI_STUB
        bool

config EFI
        bool "UEFI runtime support"
        depends on OF && !CPU_BIG_ENDIAN
        select LIBFDT
        select UCS2_STRING
        select EFI_PARAMS_FROM_FDT
        select EFI_RUNTIME_WRAPPERS
        select EFI_STUB
        select EFI_ARMSTUB
        default y
        help
          This option provides support for runtime services provided
          by UEFI firmware (such as non-volatile variables, realtime
          clock, and platform reset). A UEFI stub is also provided to
          allow the kernel to be booted as an EFI application. This
          is only useful on systems that have UEFI firmware.

config DMI
        bool "Enable support for SMBIOS (DMI) tables"
        depends on EFI
        default y
        help
          This enables SMBIOS/DMI feature for systems.

          This option is only useful on systems that have UEFI firmware.
          However, even with this option, the resultant kernel should
          continue to boot on existing non-UEFI platforms.

endmenu

menu "Userspace binary formats"

source "fs/Kconfig.binfmt"

config COMPAT
        bool "Kernel support for 32-bit EL0"
        depends on ARM64_4K_PAGES || EXPERT
        select COMPAT_BINFMT_ELF if BINFMT_ELF
        select HAVE_UID16
        select OLD_SIGSUSPEND3
        select COMPAT_OLD_SIGACTION
        help
          This option enables support for a 32-bit EL0 running under a 64-bit
          kernel at EL1. AArch32-specific components such as system calls,
          the user helper functions, VFP support and the ptrace interface are
          handled appropriately by the kernel.

          If you use a page size other than 4KB (i.e, 16KB or 64KB), please be aware
          that you will only be able to execute AArch32 binaries that were compiled
          with page size aligned segments.

          If you want to execute 32-bit userspace applications, say Y.

config SYSVIPC_COMPAT
        def_bool y
        depends on COMPAT && SYSVIPC

endmenu

menu "Power management options"

source "kernel/power/Kconfig"

config ARCH_HIBERNATION_POSSIBLE
        def_bool y
        depends on CPU_PM

config ARCH_HIBERNATION_HEADER
        def_bool y
        depends on HIBERNATION

config ARCH_SUSPEND_POSSIBLE
        def_bool y

endmenu

menu "CPU Power Management"

source "drivers/cpuidle/Kconfig"

source "drivers/cpufreq/Kconfig"

endmenu

source "net/Kconfig"

source "drivers/Kconfig"

source "drivers/firmware/Kconfig"

source "drivers/acpi/Kconfig"

source "fs/Kconfig"

source "arch/arm64/kvm/Kconfig"

source "arch/arm64/Kconfig.debug"

source "security/Kconfig"

source "crypto/Kconfig"
if CRYPTO
source "arch/arm64/crypto/Kconfig"
endif

source "lib/Kconfig"