| # 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 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 |
| 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 OPTPROBES |
| def_bool y |
| depends on KPROBES && HAVE_OPTPROBES |
| select TASKS_RCU if PREEMPTION |
| |
| config KPROBES_ON_FTRACE |
| def_bool y |
| depends on KPROBES && HAVE_KPROBES_ON_FTRACE |
| depends on DYNAMIC_FTRACE_WITH_REGS |
| help |
| If function tracer is enabled and the arch supports full |
| passing of pt_regs to function tracing, then kprobes can |
| optimize on top of function tracing. |
| |
| config UPROBES |
| def_bool n |
| depends on ARCH_SUPPORTS_UPROBES |
| help |
| Uprobes is the user-space counterpart to kprobes: they |
| enable instrumentation applications (such as 'perf probe') |
| to establish unintrusive probes in user-space binaries and |
| libraries, by executing handler functions when the probes |
| are hit by user-space applications. |
| |
| ( These probes come in the form of single-byte breakpoints, |
| managed by the kernel and kept transparent to the probed |
| application. ) |
| |
| config HAVE_64BIT_ALIGNED_ACCESS |
| def_bool 64BIT && !HAVE_EFFICIENT_UNALIGNED_ACCESS |
| help |
| Some architectures require 64 bit accesses to be 64 bit |
| aligned, which also requires structs containing 64 bit values |
| to be 64 bit aligned too. This includes some 32 bit |
| architectures which can do 64 bit accesses, as well as 64 bit |
| architectures without unaligned access. |
| |
| This symbol should be selected by an architecture if 64 bit |
| accesses are required to be 64 bit aligned in this way even |
| though it is not a 64 bit architecture. |
| |
| See Documentation/unaligned-memory-access.txt for more |
| information on the topic of unaligned memory accesses. |
| |
| config HAVE_EFFICIENT_UNALIGNED_ACCESS |
| bool |
| help |
| Some architectures are unable to perform unaligned accesses |
| without the use of get_unaligned/put_unaligned. Others are |
| unable to perform such accesses efficiently (e.g. trap on |
| unaligned access and require fixing it up in the exception |
| handler.) |
| |
| This symbol should be selected by an architecture if it can |
| perform unaligned accesses efficiently to allow different |
| code paths to be selected for these cases. Some network |
| drivers, for example, could opt to not fix up alignment |
| problems with received packets if doing so would not help |
| much. |
| |
| See Documentation/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 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 arch has an uncached kernel segment and provides the |
| # uncached_kernel_address / cached_kernel_address symbols to use it |
| # |
| config ARCH_HAS_UNCACHED_SEGMENT |
| select ARCH_HAS_DMA_PREP_COHERENT |
| 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_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. |
| |
| config HAVE_ASM_MODVERSIONS |
| bool |
| help |
| This symbol should be selected by an architecure 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 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_FUNCTION_ARG_ACCESS_API |
| bool |
| help |
| This symbol should be selected by an architecure if it supports |
| the API needed to access function arguments from pt_regs, |
| declared in asm/ptrace.h |
| |
| 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_ARCH_JUMP_LABEL_RELATIVE |
| bool |
| |
| config HAVE_RCU_TABLE_FREE |
| bool |
| |
| config HAVE_MMU_GATHER_PAGE_SIZE |
| bool |
| |
| config MMU_GATHER_NO_RANGE |
| bool |
| |
| config HAVE_MMU_GATHER_NO_GATHER |
| bool |
| |
| 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_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_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 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 ARCH_SUPPORTS_SHADOW_CALL_STACK |
| bool |
| help |
| An architecture should select this if it supports Clang's Shadow |
| Call Stack, has asm/scs.h, and implements runtime support for shadow |
| stack switching. |
| |
| config SHADOW_CALL_STACK |
| bool "Clang Shadow Call Stack" |
| depends on ARCH_SUPPORTS_SHADOW_CALL_STACK |
| 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 from |
| 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 used by other tasks and interrupt handlers in memory, which |
| means an attacker capable reading and writing arbitrary memory may |
| be able to locate them and hijack control flow by modifying shadow |
| stacks that are not currently in use. |
| |
| config SHADOW_CALL_STACK_VMAP |
| bool "Use virtually mapped shadow call stacks" |
| depends on SHADOW_CALL_STACK |
| default y |
| help |
| Use virtually mapped shadow call stacks. Selecting this option |
| provides better stack exhaustion protection, but increases per-thread |
| memory consumption as a full page is allocated for each shadow stack. |
| |
| config LTO |
| bool |
| |
| 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_THINLTO |
| bool |
| help |
| An architecture should select this if it supports Clang ThinLTO. |
| |
| config THINLTO |
| bool "Use Clang's ThinLTO (EXPERIMENTAL)" |
| depends on LTO_CLANG && ARCH_SUPPORTS_THINLTO |
| default y |
| help |
| Use ThinLTO to speed up Link Time Optimization. |
| |
| choice |
| prompt "Link-Time Optimization (LTO) (EXPERIMENTAL)" |
| default LTO_NONE |
| help |
| This option turns on Link-Time Optimization (LTO). |
| |
| config LTO_NONE |
| bool "None" |
| |
| config LTO_CLANG |
| bool "Use Clang's Link Time Optimization (LTO) (EXPERIMENTAL)" |
| depends on ARCH_SUPPORTS_LTO_CLANG |
| depends on !KASAN |
| depends on !FTRACE_MCOUNT_RECORD || HAVE_C_RECORDMCOUNT |
| depends on CC_IS_CLANG && CLANG_VERSION >= 100000 && LD_IS_LLD |
| select LTO |
| help |
| This option enables Clang's Link Time Optimization (LTO), which allows |
| the compiler to optimize the kernel globally at link time. If you |
| enable this option, the compiler generates LLVM IR instead of object |
| files, and the actual compilation from IR occurs at the LTO link step, |
| which may take several minutes. |
| |
| endchoice |
| |
| config CFI_CLANG |
| bool "Use Clang's Control Flow Integrity (CFI)" |
| depends on LTO_CLANG && KALLSYMS |
| depends on !GCOV_KERNEL |
| help |
| This option enables Clang's Control Flow Integrity (CFI), which adds |
| runtime checking for indirect function calls. |
| |
| config CFI_CLANG_SHADOW |
| bool "Use CFI shadow to speed up cross-module checks" |
| default y |
| depends on CFI_CLANG |
| help |
| If you select this option, the kernel builds a fast look-up table of |
| CFI check functions in loaded modules to reduce overhead. |
| |
| 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 is useful for finding |
| CFI violations during development. |
| |
| 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_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 |
| |
| 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 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. |
| |
| # 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_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 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 64BIT_TIME |
| def_bool y |
| 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 || 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_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 && !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 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 |
| |
| source "kernel/gcov/Kconfig" |
| |
| source "scripts/gcc-plugins/Kconfig" |
| |
| endmenu |