v4.19.13 snapshot.
diff --git a/arch/Kconfig b/arch/Kconfig
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+# 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 HAVE_IMA_KEXEC
+ bool
+
+config HOTPLUG_SMT
+ 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 STATIC_KEYS_SELFTEST
+ bool "Static key selftest"
+ depends on JUMP_LABEL
+ help
+ Boot time self-test of the branch patching code.
+
+config OPTPROBES
+ def_bool y
+ depends on KPROBES && HAVE_OPTPROBES
+ select TASKS_RCU if 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
+ def_bool n
+ depends on ARCH_SUPPORTS_UPROBES
+ help
+ Uprobes is the user-space counterpart to kprobes: they
+ enable instrumentation applications (such as 'perf probe')
+ to establish unintrusive probes in user-space binaries and
+ libraries, by executing handler functions when the probes
+ are hit by user-space applications.
+
+ ( These probes come in the form of single-byte breakpoints,
+ managed by the kernel and kept transparent to the probed
+ application. )
+
+config HAVE_64BIT_ALIGNED_ACCESS
+ def_bool 64BIT && !HAVE_EFFICIENT_UNALIGNED_ACCESS
+ help
+ Some architectures require 64 bit accesses to be 64 bit
+ aligned, which also requires structs containing 64 bit values
+ to be 64 bit aligned too. This includes some 32 bit
+ architectures which can do 64 bit accesses, as well as 64 bit
+ architectures without unaligned access.
+
+ This symbol should be selected by an architecture if 64 bit
+ accesses are required to be 64 bit aligned in this way even
+ though it is not a 64 bit architecture.
+
+ See Documentation/unaligned-memory-access.txt for more
+ information on the topic of unaligned memory accesses.
+
+config HAVE_EFFICIENT_UNALIGNED_ACCESS
+ bool
+ help
+ Some architectures are unable to perform unaligned accesses
+ without the use of get_unaligned/put_unaligned. Others are
+ unable to perform such accesses efficiently (e.g. trap on
+ unaligned access and require fixing it up in the exception
+ handler.)
+
+ This symbol should be selected by an architecture if it can
+ perform unaligned accesses efficiently to allow different
+ code paths to be selected for these cases. Some network
+ drivers, for example, could opt to not fix up alignment
+ problems with received packets if doing so would not help
+ much.
+
+ See Documentation/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_FUNCTION_ERROR_INJECTION
+ bool
+
+config HAVE_NMI
+ bool
+
+#
+# An arch should select this if it provides all these things:
+#
+# task_pt_regs() in asm/processor.h or asm/ptrace.h
+# arch_has_single_step() if there is hardware single-step support
+# arch_has_block_step() if there is hardware block-step support
+# asm/syscall.h supplying asm-generic/syscall.h interface
+# linux/regset.h user_regset interfaces
+# CORE_DUMP_USE_REGSET #define'd in linux/elf.h
+# TIF_SYSCALL_TRACE calls tracehook_report_syscall_{entry,exit}
+# TIF_NOTIFY_RESUME calls tracehook_notify_resume()
+# signal delivery calls tracehook_signal_handler()
+#
+config HAVE_ARCH_TRACEHOOK
+ bool
+
+config HAVE_DMA_CONTIGUOUS
+ bool
+
+config GENERIC_SMP_IDLE_THREAD
+ bool
+
+config GENERIC_IDLE_POLL_SETUP
+ bool
+
+config ARCH_HAS_FORTIFY_SOURCE
+ bool
+ help
+ An architecture should select this when it can successfully
+ build and run with CONFIG_FORTIFY_SOURCE.
+
+# Select if arch has all set_memory_ro/rw/x/nx() functions in asm/cacheflush.h
+config ARCH_HAS_SET_MEMORY
+ 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 HAVE_REGS_AND_STACK_ACCESS_API
+ bool
+ help
+ This symbol should be selected by an architecure if it supports
+ the API needed to access registers and stack entries from pt_regs,
+ declared in asm/ptrace.h
+ For example the kprobes-based event tracer needs this API.
+
+config HAVE_RSEQ
+ bool
+ depends on HAVE_REGS_AND_STACK_ACCESS_API
+ help
+ This symbol should be selected by an architecture if it
+ supports an implementation of restartable sequences.
+
+config HAVE_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_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_RCU_TABLE_FREE
+ bool
+
+config HAVE_RCU_TABLE_INVALIDATE
+ 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_WEAK_RELEASE_ACQUIRE
+ bool
+
+config ARCH_WANT_IPC_PARSE_VERSION
+ bool
+
+config ARCH_WANT_COMPAT_IPC_PARSE_VERSION
+ bool
+
+config ARCH_WANT_OLD_COMPAT_IPC
+ select ARCH_WANT_COMPAT_IPC_PARSE_VERSION
+ bool
+
+config HAVE_ARCH_SECCOMP_FILTER
+ bool
+ help
+ An arch should select this symbol if it provides all of these things:
+ - syscall_get_arch()
+ - syscall_get_arguments()
+ - syscall_rollback()
+ - syscall_set_return_value()
+ - SIGSYS siginfo_t support
+ - secure_computing is called from a ptrace_event()-safe context
+ - secure_computing return value is checked and a return value of -1
+ results in the system call being skipped immediately.
+ - seccomp syscall wired up
+
+config SECCOMP_FILTER
+ def_bool y
+ depends on HAVE_ARCH_SECCOMP_FILTER && SECCOMP && NET
+ help
+ Enable tasks to build secure computing environments defined
+ in terms of Berkeley Packet Filter programs which implement
+ task-defined system call filtering polices.
+
+ See Documentation/userspace-api/seccomp_filter.rst for details.
+
+config HAVE_STACKPROTECTOR
+ bool
+ help
+ An arch should select this symbol if:
+ - it has implemented a stack canary (e.g. __stack_chk_guard)
+
+config CC_HAS_STACKPROTECTOR_NONE
+ def_bool $(cc-option,-fno-stack-protector)
+
+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 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() 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 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_ARCH_TRANSPARENT_HUGEPAGE
+ bool
+
+config HAVE_ARCH_TRANSPARENT_HUGEPAGE_PUD
+ bool
+
+config HAVE_ARCH_HUGE_VMAP
+ 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 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 HAVE_COPY_THREAD_TLS
+ bool
+ help
+ Architecture provides copy_thread_tls to accept tls argument via
+ normal C parameter passing, rather than extracting the syscall
+ argument from pt_regs.
+
+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 a save_stack_trace_tsk_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 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 64BIT_TIME
+ def_bool ARCH_HAS_64BIT_TIME
+ help
+ This should be selected by all architectures that need to support
+ new system calls with a 64-bit time_t. This is relevant on all 32-bit
+ architectures, and 64-bit architectures as part of compat syscall
+ handling.
+
+config COMPAT_32BIT_TIME
+ def_bool (!64BIT && 64BIT_TIME) || 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_COHERENT_DMA_MMAP
+ bool
+
+config ARCH_NO_PREEMPT
+ 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 && !KASAN
+ ---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.
+
+ This is presently incompatible with KASAN because KASAN expects
+ the stack to map directly to the KASAN shadow map using a formula
+ that is incorrect if the stack is in vmalloc space.
+
+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 ARCH_HAS_REFCOUNT
+ bool
+ help
+ An architecture selects this when it has implemented refcount_t
+ using open coded assembly primitives that provide an optimized
+ refcount_t implementation, possibly at the expense of some full
+ refcount state checks of CONFIG_REFCOUNT_FULL=y.
+
+ The refcount overflow check behavior, however, must be retained.
+ Catching overflows is the primary security concern for protecting
+ against bugs in reference counts.
+
+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.
+
+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.
+
+source "kernel/gcov/Kconfig"
+
+source "scripts/gcc-plugins/Kconfig"
+
+endmenu