#
# General architecture dependent options
#

config CRASH_CORE
        bool

config KEXEC_CORE
        select CRASH_CORE
        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
       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 OPTPROBES
        def_bool y
        depends on KPROBES && HAVE_OPTPROBES
        depends on !PREEMPT

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
        bool "Transparent user-space probes (EXPERIMENTAL)"
        depends on UPROBE_EVENT && PERF_EVENTS
        default n
        select PERCPU_RWSEM
        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. )

          If in doubt, say "N".

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/unaligned-memory-access.txt 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_NMI_WATCHDOG
        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 USE_GENERIC_SMP_HELPERS
        bool

config GENERIC_SMP_IDLE_THREAD
       bool

config GENERIC_IDLE_POLL_SETUP
       bool

# Select if arch init_task initializer is different to init/init_task.c
config ARCH_INIT_TASK
       bool

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

# Select if arch has its private alloc_thread_info() function
config ARCH_THREAD_INFO_ALLOCATOR
        bool

config HAVE_REGS_AND_STACK_ACCESS_API
        bool
        help
          This symbol should be selected by an architecure if it supports
          the API needed to access registers and stack entries from pt_regs,
          declared in asm/ptrace.h
          For example the kprobes-based event tracer needs this API.

config HAVE_CLK
        bool
        help
          The <linux/clk.h> calls support software clock gating and
          thus are a key power management tool on many systems.

config HAVE_DMA_API_DEBUG
        bool

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_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_RCU_TABLE_FREE
        bool

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_WANT_IPC_PARSE_VERSION
        bool

config ARCH_WANT_COMPAT_IPC_PARSE_VERSION
        bool

config ARCH_WANT_OLD_COMPAT_IPC
        select ARCH_WANT_COMPAT_IPC_PARSE_VERSION
        bool

config HAVE_ARCH_SECCOMP_FILTER
        bool
        help
          An arch should select this symbol if it provides all of these things:
          - syscall_get_arch()
          - syscall_get_arguments()
          - syscall_rollback()
          - syscall_set_return_value()
          - SIGSYS siginfo_t support
          - secure_computing is called from a ptrace_event()-safe context
          - secure_computing return value is checked and a return value of -1
            results in the system call being skipped immediately.
          - seccomp syscall wired up

config SECCOMP_FILTER
        def_bool y
        depends on HAVE_ARCH_SECCOMP_FILTER && SECCOMP && NET
        help
          Enable tasks to build secure computing environments defined
          in terms of Berkeley Packet Filter programs which implement
          task-defined system call filtering polices.

          See Documentation/prctl/seccomp_filter.txt for details.

config HAVE_CC_STACKPROTECTOR
        bool
        help
          An arch should select this symbol if:
          - its compiler supports the -fstack-protector option
          - it has implemented a stack canary (e.g. __stack_chk_guard)

config CC_STACKPROTECTOR
        def_bool n
        help
          Set when a stack-protector mode is enabled, so that the build
          can enable kernel-side support for the GCC feature.

choice
        prompt "Stack Protector buffer overflow detection"
        depends on HAVE_CC_STACKPROTECTOR
        default CC_STACKPROTECTOR_NONE
        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.

config CC_STACKPROTECTOR_NONE
        bool "None"
        help
          Disable "stack-protector" GCC feature.

config CC_STACKPROTECTOR_REGULAR
        bool "Regular"
        select CC_STACKPROTECTOR
        help
          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 CC_STACKPROTECTOR_STRONG
        bool "Strong"
        select CC_STACKPROTECTOR
        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%.

endchoice

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() 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_VIRT_CPU_ACCOUNTING
        bool

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_ARCH_TRANSPARENT_HUGEPAGE
        bool

config HAVE_ARCH_TRANSPARENT_HUGEPAGE_PUD
        bool

config HAVE_ARCH_SOFT_DIRTY
        bool

config HAVE_ARCH_HUGE_VMAP
        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_UNDERSCORE_SYMBOL_PREFIX
        bool
        help
          Some architectures generate an _ in front of C symbols; things like
          module loading and assembly files need to know about this.

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

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 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_RELIABLE_STACKTRACE
        bool
        help
          Architecture has a save_stack_trace_tsk_reliable() function which
          only returns a stack trace if it can guarantee the trace is reliable.

#
# 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 REFCOUNT_FULL
        bool "Perform full reference count validation at the expense of speed"
        help
          Enabling this switches the refcounting infrastructure from a fast
          unchecked atomic_t implementation to a fully state checked
          implementation, which can be (slightly) slower but provides protections
          against various use-after-free conditions that can be used in
          security flaw exploits.

source "kernel/gcov/Kconfig"