| # 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 ARCH_HAS_SUBPAGE_FAULTS |
| bool |
| help |
| Select if the architecture can check permissions at sub-page |
| granularity (e.g. arm64 MTE). The probe_user_*() functions |
| must be implemented. |
| |
| config HOTPLUG_SMT |
| bool |
| |
| # Selected by HOTPLUG_CORE_SYNC_DEAD or HOTPLUG_CORE_SYNC_FULL |
| config HOTPLUG_CORE_SYNC |
| bool |
| |
| # Basic CPU dead synchronization selected by architecture |
| config HOTPLUG_CORE_SYNC_DEAD |
| bool |
| select HOTPLUG_CORE_SYNC |
| |
| # Full CPU synchronization with alive state selected by architecture |
| config HOTPLUG_CORE_SYNC_FULL |
| bool |
| select HOTPLUG_CORE_SYNC_DEAD if HOTPLUG_CPU |
| select HOTPLUG_CORE_SYNC |
| |
| config HOTPLUG_SPLIT_STARTUP |
| bool |
| select HOTPLUG_CORE_SYNC_FULL |
| |
| config HOTPLUG_PARALLEL |
| bool |
| select HOTPLUG_SPLIT_STARTUP |
| |
| config GENERIC_ENTRY |
| bool |
| |
| config KPROBES |
| bool "Kprobes" |
| depends on MODULES |
| depends on HAVE_KPROBES |
| select KALLSYMS |
| select TASKS_RCU if PREEMPTION |
| 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 |
| select OBJTOOL if HAVE_JUMP_LABEL_HACK |
| help |
| This option enables a transparent branch optimization that |
| makes certain almost-always-true or almost-always-false branch |
| conditions even cheaper to execute within the kernel. |
| |
| Certain performance-sensitive kernel code, such as trace points, |
| scheduler functionality, networking code and KVM have such |
| branches and include support for this optimization technique. |
| |
| If it is detected that the compiler has support for "asm goto", |
| the kernel will compile such branches with just a nop |
| instruction. When the condition flag is toggled to true, the |
| nop will be converted to a jump instruction to execute the |
| conditional block of instructions. |
| |
| This technique lowers overhead and stress on the branch prediction |
| of the processor and generally makes the kernel faster. The update |
| of the condition is slower, but those are always very rare. |
| |
| ( On 32-bit x86, the necessary options added to the compiler |
| flags may increase the size of the kernel slightly. ) |
| |
| config STATIC_KEYS_SELFTEST |
| bool "Static key selftest" |
| depends on JUMP_LABEL |
| help |
| Boot time self-test of the branch patching code. |
| |
| config STATIC_CALL_SELFTEST |
| bool "Static call selftest" |
| depends on HAVE_STATIC_CALL |
| help |
| Boot time self-test of the call patching code. |
| |
| config OPTPROBES |
| def_bool y |
| depends on KPROBES && HAVE_OPTPROBES |
| select TASKS_RCU if PREEMPTION |
| |
| config KPROBES_ON_FTRACE |
| def_bool y |
| depends on KPROBES && HAVE_KPROBES_ON_FTRACE |
| depends on DYNAMIC_FTRACE_WITH_REGS |
| help |
| If function tracer is enabled and the arch supports full |
| passing of pt_regs to function tracing, then kprobes can |
| optimize on top of function tracing. |
| |
| config UPROBES |
| def_bool n |
| depends on ARCH_SUPPORTS_UPROBES |
| help |
| Uprobes is the user-space counterpart to kprobes: they |
| enable instrumentation applications (such as 'perf probe') |
| to establish unintrusive probes in user-space binaries and |
| libraries, by executing handler functions when the probes |
| are hit by user-space applications. |
| |
| ( These probes come in the form of single-byte breakpoints, |
| managed by the kernel and kept transparent to the probed |
| application. ) |
| |
| config HAVE_64BIT_ALIGNED_ACCESS |
| def_bool 64BIT && !HAVE_EFFICIENT_UNALIGNED_ACCESS |
| help |
| Some architectures require 64 bit accesses to be 64 bit |
| aligned, which also requires structs containing 64 bit values |
| to be 64 bit aligned too. This includes some 32 bit |
| architectures which can do 64 bit accesses, as well as 64 bit |
| architectures without unaligned access. |
| |
| This symbol should be selected by an architecture if 64 bit |
| accesses are required to be 64 bit aligned in this way even |
| though it is not a 64 bit architecture. |
| |
| See Documentation/core-api/unaligned-memory-access.rst for |
| more information on the topic of unaligned memory accesses. |
| |
| config HAVE_EFFICIENT_UNALIGNED_ACCESS |
| bool |
| help |
| Some architectures are unable to perform unaligned accesses |
| without the use of get_unaligned/put_unaligned. Others are |
| unable to perform such accesses efficiently (e.g. trap on |
| unaligned access and require fixing it up in the exception |
| handler.) |
| |
| This symbol should be selected by an architecture if it can |
| perform unaligned accesses efficiently to allow different |
| code paths to be selected for these cases. Some network |
| drivers, for example, could opt to not fix up alignment |
| problems with received packets if doing so would not help |
| much. |
| |
| See Documentation/core-api/unaligned-memory-access.rst for more |
| information on the topic of unaligned memory accesses. |
| |
| config ARCH_USE_BUILTIN_BSWAP |
| bool |
| help |
| Modern versions of GCC (since 4.4) have builtin functions |
| for handling byte-swapping. Using these, instead of the old |
| inline assembler that the architecture code provides in the |
| __arch_bswapXX() macros, allows the compiler to see what's |
| happening and offers more opportunity for optimisation. In |
| particular, the compiler will be able to combine the byteswap |
| with a nearby load or store and use load-and-swap or |
| store-and-swap instructions if the architecture has them. It |
| should almost *never* result in code which is worse than the |
| hand-coded assembler in <asm/swab.h>. But just in case it |
| does, the use of the builtins is optional. |
| |
| Any architecture with load-and-swap or store-and-swap |
| instructions should set this. And it shouldn't hurt to set it |
| on architectures that don't have such instructions. |
| |
| config KRETPROBES |
| def_bool y |
| depends on KPROBES && (HAVE_KRETPROBES || HAVE_RETHOOK) |
| |
| config KRETPROBE_ON_RETHOOK |
| def_bool y |
| depends on HAVE_RETHOOK |
| depends on KRETPROBES |
| select RETHOOK |
| |
| config USER_RETURN_NOTIFIER |
| bool |
| depends on HAVE_USER_RETURN_NOTIFIER |
| help |
| Provide a kernel-internal notification when a cpu is about to |
| switch to user mode. |
| |
| config HAVE_IOREMAP_PROT |
| bool |
| |
| config HAVE_KPROBES |
| bool |
| |
| config HAVE_KRETPROBES |
| bool |
| |
| config HAVE_OPTPROBES |
| bool |
| |
| config HAVE_KPROBES_ON_FTRACE |
| bool |
| |
| config ARCH_CORRECT_STACKTRACE_ON_KRETPROBE |
| bool |
| help |
| Since kretprobes modifies return address on the stack, the |
| stacktrace may see the kretprobe trampoline address instead |
| of correct one. If the architecture stacktrace code and |
| unwinder can adjust such entries, select this configuration. |
| |
| config HAVE_FUNCTION_ERROR_INJECTION |
| bool |
| |
| config HAVE_NMI |
| bool |
| |
| config HAVE_FUNCTION_DESCRIPTORS |
| bool |
| |
| config TRACE_IRQFLAGS_SUPPORT |
| bool |
| |
| config TRACE_IRQFLAGS_NMI_SUPPORT |
| bool |
| |
| # |
| # An arch should select this if it provides all these things: |
| # |
| # task_pt_regs() in asm/processor.h or asm/ptrace.h |
| # arch_has_single_step() if there is hardware single-step support |
| # arch_has_block_step() if there is hardware block-step support |
| # asm/syscall.h supplying asm-generic/syscall.h interface |
| # linux/regset.h user_regset interfaces |
| # CORE_DUMP_USE_REGSET #define'd in linux/elf.h |
| # TIF_SYSCALL_TRACE calls ptrace_report_syscall_{entry,exit} |
| # TIF_NOTIFY_RESUME calls resume_user_mode_work() |
| # |
| config HAVE_ARCH_TRACEHOOK |
| bool |
| |
| config HAVE_DMA_CONTIGUOUS |
| bool |
| |
| config GENERIC_SMP_IDLE_THREAD |
| bool |
| |
| config GENERIC_IDLE_POLL_SETUP |
| bool |
| |
| config ARCH_HAS_FORTIFY_SOURCE |
| bool |
| help |
| An architecture should select this when it can successfully |
| build and run with CONFIG_FORTIFY_SOURCE. |
| |
| # |
| # Select if the arch provides a historic keepinit alias for the retain_initrd |
| # command line option |
| # |
| config ARCH_HAS_KEEPINITRD |
| bool |
| |
| # Select if arch has all set_memory_ro/rw/x/nx() functions in asm/cacheflush.h |
| config ARCH_HAS_SET_MEMORY |
| bool |
| |
| # Select if arch has all set_direct_map_invalid/default() functions |
| config ARCH_HAS_SET_DIRECT_MAP |
| bool |
| |
| # |
| # Select if the architecture provides the arch_dma_set_uncached symbol to |
| # either provide an uncached segment alias for a DMA allocation, or |
| # to remap the page tables in place. |
| # |
| config ARCH_HAS_DMA_SET_UNCACHED |
| bool |
| |
| # |
| # Select if the architectures provides the arch_dma_clear_uncached symbol |
| # to undo an in-place page table remap for uncached access. |
| # |
| config ARCH_HAS_DMA_CLEAR_UNCACHED |
| bool |
| |
| config ARCH_HAS_CPU_FINALIZE_INIT |
| bool |
| |
| # Select if arch init_task must go in the __init_task_data section |
| config ARCH_TASK_STRUCT_ON_STACK |
| bool |
| |
| # Select if arch has its private alloc_task_struct() function |
| config ARCH_TASK_STRUCT_ALLOCATOR |
| bool |
| |
| config HAVE_ARCH_THREAD_STRUCT_WHITELIST |
| bool |
| depends on !ARCH_TASK_STRUCT_ALLOCATOR |
| help |
| An architecture should select this to provide hardened usercopy |
| knowledge about what region of the thread_struct should be |
| whitelisted for copying to userspace. Normally this is only the |
| FPU registers. Specifically, arch_thread_struct_whitelist() |
| should be implemented. Without this, the entire thread_struct |
| field in task_struct will be left whitelisted. |
| |
| # Select if arch has its private alloc_thread_stack() function |
| config ARCH_THREAD_STACK_ALLOCATOR |
| bool |
| |
| # Select if arch wants to size task_struct dynamically via arch_task_struct_size: |
| config ARCH_WANTS_DYNAMIC_TASK_STRUCT |
| bool |
| |
| config ARCH_WANTS_NO_INSTR |
| bool |
| help |
| An architecture should select this if the noinstr macro is being used on |
| functions to denote that the toolchain should avoid instrumenting such |
| functions and is required for correctness. |
| |
| config ARCH_32BIT_OFF_T |
| bool |
| depends on !64BIT |
| help |
| All new 32-bit architectures should have 64-bit off_t type on |
| userspace side which corresponds to the loff_t kernel type. This |
| is the requirement for modern ABIs. Some existing architectures |
| still support 32-bit off_t. This option is enabled for all such |
| architectures explicitly. |
| |
| # Selected by 64 bit architectures which have a 32 bit f_tinode in struct ustat |
| config ARCH_32BIT_USTAT_F_TINODE |
| bool |
| |
| config HAVE_ASM_MODVERSIONS |
| bool |
| help |
| This symbol should be selected by an architecture if it provides |
| <asm/asm-prototypes.h> to support the module versioning for symbols |
| exported from assembly code. |
| |
| config HAVE_REGS_AND_STACK_ACCESS_API |
| bool |
| help |
| This symbol should be selected by an architecture if it supports |
| the API needed to access registers and stack entries from pt_regs, |
| declared in asm/ptrace.h |
| For example the kprobes-based event tracer needs this API. |
| |
| config HAVE_RSEQ |
| bool |
| depends on HAVE_REGS_AND_STACK_ACCESS_API |
| help |
| This symbol should be selected by an architecture if it |
| supports an implementation of restartable sequences. |
| |
| config HAVE_RUST |
| bool |
| help |
| This symbol should be selected by an architecture if it |
| supports Rust. |
| |
| config HAVE_FUNCTION_ARG_ACCESS_API |
| bool |
| help |
| This symbol should be selected by an architecture if it supports |
| the API needed to access function arguments from pt_regs, |
| declared in asm/ptrace.h |
| |
| config HAVE_HW_BREAKPOINT |
| bool |
| depends on PERF_EVENTS |
| |
| config HAVE_MIXED_BREAKPOINTS_REGS |
| bool |
| depends on HAVE_HW_BREAKPOINT |
| help |
| Depending on the arch implementation of hardware breakpoints, |
| some of them have separate registers for data and instruction |
| breakpoints addresses, others have mixed registers to store |
| them but define the access type in a control register. |
| Select this option if your arch implements breakpoints under the |
| latter fashion. |
| |
| config HAVE_USER_RETURN_NOTIFIER |
| bool |
| |
| config HAVE_PERF_EVENTS_NMI |
| bool |
| help |
| System hardware can generate an NMI using the perf event |
| subsystem. Also has support for calculating CPU cycle events |
| to determine how many clock cycles in a given period. |
| |
| config HAVE_HARDLOCKUP_DETECTOR_PERF |
| bool |
| depends on HAVE_PERF_EVENTS_NMI |
| help |
| The arch chooses to use the generic perf-NMI-based hardlockup |
| detector. Must define HAVE_PERF_EVENTS_NMI. |
| |
| config HAVE_HARDLOCKUP_DETECTOR_ARCH |
| bool |
| help |
| The arch provides its own hardlockup detector implementation instead |
| of the generic ones. |
| |
| It uses the same command line parameters, and sysctl interface, |
| as the generic hardlockup detectors. |
| |
| config HAVE_PERF_REGS |
| bool |
| help |
| Support selective register dumps for perf events. This includes |
| bit-mapping of each registers and a unique architecture id. |
| |
| config HAVE_PERF_USER_STACK_DUMP |
| bool |
| help |
| Support user stack dumps for perf event samples. This needs |
| access to the user stack pointer which is not unified across |
| architectures. |
| |
| config HAVE_ARCH_JUMP_LABEL |
| bool |
| |
| config HAVE_ARCH_JUMP_LABEL_RELATIVE |
| bool |
| |
| config MMU_GATHER_TABLE_FREE |
| bool |
| |
| config MMU_GATHER_RCU_TABLE_FREE |
| bool |
| select MMU_GATHER_TABLE_FREE |
| |
| config MMU_GATHER_PAGE_SIZE |
| bool |
| |
| config MMU_GATHER_NO_RANGE |
| bool |
| select MMU_GATHER_MERGE_VMAS |
| |
| config MMU_GATHER_NO_FLUSH_CACHE |
| bool |
| |
| config MMU_GATHER_MERGE_VMAS |
| bool |
| |
| config MMU_GATHER_NO_GATHER |
| bool |
| depends on MMU_GATHER_TABLE_FREE |
| |
| config ARCH_WANT_IRQS_OFF_ACTIVATE_MM |
| bool |
| help |
| Temporary select until all architectures can be converted to have |
| irqs disabled over activate_mm. Architectures that do IPI based TLB |
| shootdowns should enable this. |
| |
| # Use normal mm refcounting for MMU_LAZY_TLB kernel thread references. |
| # MMU_LAZY_TLB_REFCOUNT=n can improve the scalability of context switching |
| # to/from kernel threads when the same mm is running on a lot of CPUs (a large |
| # multi-threaded application), by reducing contention on the mm refcount. |
| # |
| # This can be disabled if the architecture ensures no CPUs are using an mm as a |
| # "lazy tlb" beyond its final refcount (i.e., by the time __mmdrop frees the mm |
| # or its kernel page tables). This could be arranged by arch_exit_mmap(), or |
| # final exit(2) TLB flush, for example. |
| # |
| # To implement this, an arch *must*: |
| # Ensure the _lazy_tlb variants of mmgrab/mmdrop are used when manipulating |
| # the lazy tlb reference of a kthread's ->active_mm (non-arch code has been |
| # converted already). |
| config MMU_LAZY_TLB_REFCOUNT |
| def_bool y |
| depends on !MMU_LAZY_TLB_SHOOTDOWN |
| |
| # This option allows MMU_LAZY_TLB_REFCOUNT=n. It ensures no CPUs are using an |
| # mm as a lazy tlb beyond its last reference count, by shooting down these |
| # users before the mm is deallocated. __mmdrop() first IPIs all CPUs that may |
| # be using the mm as a lazy tlb, so that they may switch themselves to using |
| # init_mm for their active mm. mm_cpumask(mm) is used to determine which CPUs |
| # may be using mm as a lazy tlb mm. |
| # |
| # To implement this, an arch *must*: |
| # - At the time of the final mmdrop of the mm, ensure mm_cpumask(mm) contains |
| # at least all possible CPUs in which the mm is lazy. |
| # - It must meet the requirements for MMU_LAZY_TLB_REFCOUNT=n (see above). |
| config MMU_LAZY_TLB_SHOOTDOWN |
| bool |
| |
| config ARCH_HAVE_NMI_SAFE_CMPXCHG |
| bool |
| |
| config ARCH_HAS_NMI_SAFE_THIS_CPU_OPS |
| bool |
| |
| config HAVE_ALIGNED_STRUCT_PAGE |
| bool |
| help |
| This makes sure that struct pages are double word aligned and that |
| e.g. the SLUB allocator can perform double word atomic operations |
| on a struct page for better performance. However selecting this |
| might increase the size of a struct page by a word. |
| |
| config HAVE_CMPXCHG_LOCAL |
| bool |
| |
| config HAVE_CMPXCHG_DOUBLE |
| bool |
| |
| config ARCH_WEAK_RELEASE_ACQUIRE |
| bool |
| |
| config ARCH_WANT_IPC_PARSE_VERSION |
| bool |
| |
| config ARCH_WANT_COMPAT_IPC_PARSE_VERSION |
| bool |
| |
| config ARCH_WANT_OLD_COMPAT_IPC |
| select ARCH_WANT_COMPAT_IPC_PARSE_VERSION |
| bool |
| |
| config HAVE_ARCH_SECCOMP |
| bool |
| help |
| An arch should select this symbol to support seccomp mode 1 (the fixed |
| syscall policy), and must provide an overrides for __NR_seccomp_sigreturn, |
| and compat syscalls if the asm-generic/seccomp.h defaults need adjustment: |
| - __NR_seccomp_read_32 |
| - __NR_seccomp_write_32 |
| - __NR_seccomp_exit_32 |
| - __NR_seccomp_sigreturn_32 |
| |
| config HAVE_ARCH_SECCOMP_FILTER |
| bool |
| select HAVE_ARCH_SECCOMP |
| help |
| An arch should select this symbol if it provides all of these things: |
| - all the requirements for HAVE_ARCH_SECCOMP |
| - syscall_get_arch() |
| - syscall_get_arguments() |
| - syscall_rollback() |
| - syscall_set_return_value() |
| - SIGSYS siginfo_t support |
| - secure_computing is called from a ptrace_event()-safe context |
| - secure_computing return value is checked and a return value of -1 |
| results in the system call being skipped immediately. |
| - seccomp syscall wired up |
| - if !HAVE_SPARSE_SYSCALL_NR, have SECCOMP_ARCH_NATIVE, |
| SECCOMP_ARCH_NATIVE_NR, SECCOMP_ARCH_NATIVE_NAME defined. If |
| COMPAT is supported, have the SECCOMP_ARCH_COMPAT* defines too. |
| |
| config SECCOMP |
| prompt "Enable seccomp to safely execute untrusted bytecode" |
| def_bool y |
| depends on HAVE_ARCH_SECCOMP |
| help |
| This kernel feature is useful for number crunching applications |
| that may need to handle untrusted bytecode during their |
| execution. By using pipes or other transports made available |
| to the process as file descriptors supporting the read/write |
| syscalls, it's possible to isolate those applications in their |
| own address space using seccomp. Once seccomp is enabled via |
| prctl(PR_SET_SECCOMP) or the seccomp() syscall, it cannot be |
| disabled and the task is only allowed to execute a few safe |
| syscalls defined by each seccomp mode. |
| |
| If unsure, say Y. |
| |
| config SECCOMP_FILTER |
| def_bool y |
| depends on HAVE_ARCH_SECCOMP_FILTER && SECCOMP && NET |
| help |
| Enable tasks to build secure computing environments defined |
| in terms of Berkeley Packet Filter programs which implement |
| task-defined system call filtering polices. |
| |
| See Documentation/userspace-api/seccomp_filter.rst for details. |
| |
| config SECCOMP_CACHE_DEBUG |
| bool "Show seccomp filter cache status in /proc/pid/seccomp_cache" |
| depends on SECCOMP_FILTER && !HAVE_SPARSE_SYSCALL_NR |
| depends on PROC_FS |
| help |
| This enables the /proc/pid/seccomp_cache interface to monitor |
| seccomp cache data. The file format is subject to change. Reading |
| the file requires CAP_SYS_ADMIN. |
| |
| This option is for debugging only. Enabling presents the risk that |
| an adversary may be able to infer the seccomp filter logic. |
| |
| If unsure, say N. |
| |
| config HAVE_ARCH_STACKLEAK |
| bool |
| help |
| An architecture should select this if it has the code which |
| fills the used part of the kernel stack with the STACKLEAK_POISON |
| value before returning from system calls. |
| |
| config HAVE_STACKPROTECTOR |
| bool |
| help |
| An arch should select this symbol if: |
| - it has implemented a stack canary (e.g. __stack_chk_guard) |
| |
| config STACKPROTECTOR |
| bool "Stack Protector buffer overflow detection" |
| depends on HAVE_STACKPROTECTOR |
| depends on $(cc-option,-fstack-protector) |
| default y |
| help |
| This option turns on the "stack-protector" GCC feature. This |
| feature puts, at the beginning of functions, a canary value on |
| the stack just before the return address, and validates |
| the value just before actually returning. Stack based buffer |
| overflows (that need to overwrite this return address) now also |
| overwrite the canary, which gets detected and the attack is then |
| neutralized via a kernel panic. |
| |
| Functions will have the stack-protector canary logic added if they |
| have an 8-byte or larger character array on the stack. |
| |
| This feature requires gcc version 4.2 or above, or a distribution |
| gcc with the feature backported ("-fstack-protector"). |
| |
| On an x86 "defconfig" build, this feature adds canary checks to |
| about 3% of all kernel functions, which increases kernel code size |
| by about 0.3%. |
| |
| config STACKPROTECTOR_STRONG |
| bool "Strong Stack Protector" |
| depends on STACKPROTECTOR |
| depends on $(cc-option,-fstack-protector-strong) |
| default y |
| help |
| Functions will have the stack-protector canary logic added in any |
| of the following conditions: |
| |
| - local variable's address used as part of the right hand side of an |
| assignment or function argument |
| - local variable is an array (or union containing an array), |
| regardless of array type or length |
| - uses register local variables |
| |
| This feature requires gcc version 4.9 or above, or a distribution |
| gcc with the feature backported ("-fstack-protector-strong"). |
| |
| On an x86 "defconfig" build, this feature adds canary checks to |
| about 20% of all kernel functions, which increases the kernel code |
| size by about 2%. |
| |
| config ARCH_SUPPORTS_SHADOW_CALL_STACK |
| bool |
| help |
| An architecture should select this if it supports the compiler's |
| Shadow Call Stack and implements runtime support for shadow stack |
| switching. |
| |
| config SHADOW_CALL_STACK |
| bool "Shadow Call Stack" |
| depends on ARCH_SUPPORTS_SHADOW_CALL_STACK |
| depends on DYNAMIC_FTRACE_WITH_ARGS || DYNAMIC_FTRACE_WITH_REGS || !FUNCTION_GRAPH_TRACER |
| help |
| This option enables the compiler's Shadow Call Stack, which |
| uses a shadow stack to protect function return addresses from |
| being overwritten by an attacker. More information can be found |
| in the compiler's documentation: |
| |
| - Clang: https://clang.llvm.org/docs/ShadowCallStack.html |
| - GCC: https://gcc.gnu.org/onlinedocs/gcc/Instrumentation-Options.html#Instrumentation-Options |
| |
| Note that security guarantees in the kernel differ from the |
| ones documented for user space. The kernel must store addresses |
| of shadow stacks in memory, which means an attacker capable of |
| reading and writing arbitrary memory may be able to locate them |
| and hijack control flow by modifying the stacks. |
| |
| config DYNAMIC_SCS |
| bool |
| help |
| Set by the arch code if it relies on code patching to insert the |
| shadow call stack push and pop instructions rather than on the |
| compiler. |
| |
| config LTO |
| bool |
| help |
| Selected if the kernel will be built using the compiler's LTO feature. |
| |
| config LTO_CLANG |
| bool |
| select LTO |
| help |
| Selected if the kernel will be built using Clang's LTO feature. |
| |
| config ARCH_SUPPORTS_LTO_CLANG |
| bool |
| help |
| An architecture should select this option if it supports: |
| - compiling with Clang, |
| - compiling inline assembly with Clang's integrated assembler, |
| - and linking with LLD. |
| |
| config ARCH_SUPPORTS_LTO_CLANG_THIN |
| bool |
| help |
| An architecture should select this option if it can support Clang's |
| ThinLTO mode. |
| |
| config HAS_LTO_CLANG |
| def_bool y |
| depends on CC_IS_CLANG && LD_IS_LLD && AS_IS_LLVM |
| depends on $(success,$(NM) --help | head -n 1 | grep -qi llvm) |
| depends on $(success,$(AR) --help | head -n 1 | grep -qi llvm) |
| depends on ARCH_SUPPORTS_LTO_CLANG |
| depends on !FTRACE_MCOUNT_USE_RECORDMCOUNT |
| depends on !KASAN || KASAN_HW_TAGS |
| depends on !GCOV_KERNEL |
| help |
| The compiler and Kconfig options support building with Clang's |
| LTO. |
| |
| choice |
| prompt "Link Time Optimization (LTO)" |
| default LTO_NONE |
| help |
| This option enables Link Time Optimization (LTO), which allows the |
| compiler to optimize binaries globally. |
| |
| If unsure, select LTO_NONE. Note that LTO is very resource-intensive |
| so it's disabled by default. |
| |
| config LTO_NONE |
| bool "None" |
| help |
| Build the kernel normally, without Link Time Optimization (LTO). |
| |
| config LTO_CLANG_FULL |
| bool "Clang Full LTO (EXPERIMENTAL)" |
| depends on HAS_LTO_CLANG |
| depends on !COMPILE_TEST |
| select LTO_CLANG |
| help |
| This option enables Clang's full Link Time Optimization (LTO), which |
| allows the compiler to optimize the kernel globally. If you enable |
| this option, the compiler generates LLVM bitcode instead of ELF |
| object files, and the actual compilation from bitcode happens at |
| the LTO link step, which may take several minutes depending on the |
| kernel configuration. More information can be found from LLVM's |
| documentation: |
| |
| https://llvm.org/docs/LinkTimeOptimization.html |
| |
| During link time, this option can use a large amount of RAM, and |
| may take much longer than the ThinLTO option. |
| |
| config LTO_CLANG_THIN |
| bool "Clang ThinLTO (EXPERIMENTAL)" |
| depends on HAS_LTO_CLANG && ARCH_SUPPORTS_LTO_CLANG_THIN |
| select LTO_CLANG |
| help |
| This option enables Clang's ThinLTO, which allows for parallel |
| optimization and faster incremental compiles compared to the |
| CONFIG_LTO_CLANG_FULL option. More information can be found |
| from Clang's documentation: |
| |
| https://clang.llvm.org/docs/ThinLTO.html |
| |
| If unsure, say Y. |
| endchoice |
| |
| config ARCH_SUPPORTS_CFI_CLANG |
| bool |
| help |
| An architecture should select this option if it can support Clang's |
| Control-Flow Integrity (CFI) checking. |
| |
| config ARCH_USES_CFI_TRAPS |
| bool |
| |
| config CFI_CLANG |
| bool "Use Clang's Control Flow Integrity (CFI)" |
| depends on ARCH_SUPPORTS_CFI_CLANG |
| depends on $(cc-option,-fsanitize=kcfi) |
| help |
| This option enables Clang’s forward-edge Control Flow Integrity |
| (CFI) checking, where the compiler injects a runtime check to each |
| indirect function call to ensure the target is a valid function with |
| the correct static type. This restricts possible call targets and |
| makes it more difficult for an attacker to exploit bugs that allow |
| the modification of stored function pointers. More information can be |
| found from Clang's documentation: |
| |
| https://clang.llvm.org/docs/ControlFlowIntegrity.html |
| |
| config CFI_PERMISSIVE |
| bool "Use CFI in permissive mode" |
| depends on CFI_CLANG |
| help |
| When selected, Control Flow Integrity (CFI) violations result in a |
| warning instead of a kernel panic. This option should only be used |
| for finding indirect call type mismatches during development. |
| |
| If unsure, say N. |
| |
| config HAVE_ARCH_WITHIN_STACK_FRAMES |
| bool |
| help |
| An architecture should select this if it can walk the kernel stack |
| frames to determine if an object is part of either the arguments |
| or local variables (i.e. that it excludes saved return addresses, |
| and similar) by implementing an inline arch_within_stack_frames(), |
| which is used by CONFIG_HARDENED_USERCOPY. |
| |
| config HAVE_CONTEXT_TRACKING_USER |
| bool |
| help |
| Provide kernel/user boundaries probes necessary for subsystems |
| that need it, such as userspace RCU extended quiescent state. |
| Syscalls need to be wrapped inside user_exit()-user_enter(), either |
| optimized behind static key or through the slow path using TIF_NOHZ |
| flag. Exceptions handlers must be wrapped as well. Irqs are already |
| protected inside ct_irq_enter/ct_irq_exit() but preemption or signal |
| handling on irq exit still need to be protected. |
| |
| config HAVE_CONTEXT_TRACKING_USER_OFFSTACK |
| bool |
| help |
| Architecture neither relies on exception_enter()/exception_exit() |
| nor on schedule_user(). Also preempt_schedule_notrace() and |
| preempt_schedule_irq() can't be called in a preemptible section |
| while context tracking is CONTEXT_USER. This feature reflects a sane |
| entry implementation where the following requirements are met on |
| critical entry code, ie: before user_exit() or after user_enter(): |
| |
| - Critical entry code isn't preemptible (or better yet: |
| not interruptible). |
| - No use of RCU read side critical sections, unless ct_nmi_enter() |
| got called. |
| - No use of instrumentation, unless instrumentation_begin() got |
| called. |
| |
| config HAVE_TIF_NOHZ |
| bool |
| help |
| Arch relies on TIF_NOHZ and syscall slow path to implement context |
| tracking calls to user_enter()/user_exit(). |
| |
| config HAVE_VIRT_CPU_ACCOUNTING |
| bool |
| |
| config HAVE_VIRT_CPU_ACCOUNTING_IDLE |
| bool |
| help |
| Architecture has its own way to account idle CPU time and therefore |
| doesn't implement vtime_account_idle(). |
| |
| config ARCH_HAS_SCALED_CPUTIME |
| bool |
| |
| config HAVE_VIRT_CPU_ACCOUNTING_GEN |
| bool |
| default y if 64BIT |
| help |
| With VIRT_CPU_ACCOUNTING_GEN, cputime_t becomes 64-bit. |
| Before enabling this option, arch code must be audited |
| to ensure there are no races in concurrent read/write of |
| cputime_t. For example, reading/writing 64-bit cputime_t on |
| some 32-bit arches may require multiple accesses, so proper |
| locking is needed to protect against concurrent accesses. |
| |
| config HAVE_IRQ_TIME_ACCOUNTING |
| bool |
| help |
| Archs need to ensure they use a high enough resolution clock to |
| support irq time accounting and then call enable_sched_clock_irqtime(). |
| |
| config HAVE_MOVE_PUD |
| bool |
| help |
| Architectures that select this are able to move page tables at the |
| PUD level. If there are only 3 page table levels, the move effectively |
| happens at the PGD level. |
| |
| config HAVE_MOVE_PMD |
| bool |
| help |
| Archs that select this are able to move page tables at the PMD level. |
| |
| config HAVE_ARCH_TRANSPARENT_HUGEPAGE |
| bool |
| |
| config HAVE_ARCH_TRANSPARENT_HUGEPAGE_PUD |
| bool |
| |
| config HAVE_ARCH_HUGE_VMAP |
| bool |
| |
| # |
| # Archs that select this would be capable of PMD-sized vmaps (i.e., |
| # arch_vmap_pmd_supported() returns true). The VM_ALLOW_HUGE_VMAP flag |
| # must be used to enable allocations to use hugepages. |
| # |
| config HAVE_ARCH_HUGE_VMALLOC |
| depends on HAVE_ARCH_HUGE_VMAP |
| bool |
| |
| config ARCH_WANT_HUGE_PMD_SHARE |
| bool |
| |
| config HAVE_ARCH_SOFT_DIRTY |
| bool |
| |
| config HAVE_MOD_ARCH_SPECIFIC |
| bool |
| help |
| The arch uses struct mod_arch_specific to store data. Many arches |
| just need a simple module loader without arch specific data - those |
| should not enable this. |
| |
| config MODULES_USE_ELF_RELA |
| bool |
| help |
| Modules only use ELF RELA relocations. Modules with ELF REL |
| relocations will give an error. |
| |
| config MODULES_USE_ELF_REL |
| bool |
| help |
| Modules only use ELF REL relocations. Modules with ELF RELA |
| relocations will give an error. |
| |
| config ARCH_WANTS_MODULES_DATA_IN_VMALLOC |
| bool |
| help |
| For architectures like powerpc/32 which have constraints on module |
| allocation and need to allocate module data outside of module area. |
| |
| config HAVE_IRQ_EXIT_ON_IRQ_STACK |
| bool |
| help |
| Architecture doesn't only execute the irq handler on the irq stack |
| but also irq_exit(). This way we can process softirqs on this irq |
| stack instead of switching to a new one when we call __do_softirq() |
| in the end of an hardirq. |
| This spares a stack switch and improves cache usage on softirq |
| processing. |
| |
| config HAVE_SOFTIRQ_ON_OWN_STACK |
| bool |
| help |
| Architecture provides a function to run __do_softirq() on a |
| separate stack. |
| |
| config SOFTIRQ_ON_OWN_STACK |
| def_bool HAVE_SOFTIRQ_ON_OWN_STACK && !PREEMPT_RT |
| |
| config ALTERNATE_USER_ADDRESS_SPACE |
| bool |
| help |
| Architectures set this when the CPU uses separate address |
| spaces for kernel and user space pointers. In this case, the |
| access_ok() check on a __user pointer is skipped. |
| |
| config PGTABLE_LEVELS |
| int |
| default 2 |
| |
| config ARCH_HAS_ELF_RANDOMIZE |
| bool |
| help |
| An architecture supports choosing randomized locations for |
| stack, mmap, brk, and ET_DYN. Defined functions: |
| - arch_mmap_rnd() |
| - arch_randomize_brk() |
| |
| config HAVE_ARCH_MMAP_RND_BITS |
| bool |
| help |
| An arch should select this symbol if it supports setting a variable |
| number of bits for use in establishing the base address for mmap |
| allocations, has MMU enabled and provides values for both: |
| - ARCH_MMAP_RND_BITS_MIN |
| - ARCH_MMAP_RND_BITS_MAX |
| |
| config HAVE_EXIT_THREAD |
| bool |
| help |
| An architecture implements exit_thread. |
| |
| config ARCH_MMAP_RND_BITS_MIN |
| int |
| |
| config ARCH_MMAP_RND_BITS_MAX |
| int |
| |
| config ARCH_MMAP_RND_BITS_DEFAULT |
| int |
| |
| config ARCH_MMAP_RND_BITS |
| int "Number of bits to use for ASLR of mmap base address" if EXPERT |
| range ARCH_MMAP_RND_BITS_MIN ARCH_MMAP_RND_BITS_MAX |
| default ARCH_MMAP_RND_BITS_DEFAULT if ARCH_MMAP_RND_BITS_DEFAULT |
| default ARCH_MMAP_RND_BITS_MIN |
| depends on HAVE_ARCH_MMAP_RND_BITS |
| help |
| This value can be used to select the number of bits to use to |
| determine the random offset to the base address of vma regions |
| resulting from mmap allocations. This value will be bounded |
| by the architecture's minimum and maximum supported values. |
| |
| This value can be changed after boot using the |
| /proc/sys/vm/mmap_rnd_bits tunable |
| |
| config HAVE_ARCH_MMAP_RND_COMPAT_BITS |
| bool |
| help |
| An arch should select this symbol if it supports running applications |
| in compatibility mode, supports setting a variable number of bits for |
| use in establishing the base address for mmap allocations, has MMU |
| enabled and provides values for both: |
| - ARCH_MMAP_RND_COMPAT_BITS_MIN |
| - ARCH_MMAP_RND_COMPAT_BITS_MAX |
| |
| config ARCH_MMAP_RND_COMPAT_BITS_MIN |
| int |
| |
| config ARCH_MMAP_RND_COMPAT_BITS_MAX |
| int |
| |
| config ARCH_MMAP_RND_COMPAT_BITS_DEFAULT |
| int |
| |
| config ARCH_MMAP_RND_COMPAT_BITS |
| int "Number of bits to use for ASLR of mmap base address for compatible applications" if EXPERT |
| range ARCH_MMAP_RND_COMPAT_BITS_MIN ARCH_MMAP_RND_COMPAT_BITS_MAX |
| default ARCH_MMAP_RND_COMPAT_BITS_DEFAULT if ARCH_MMAP_RND_COMPAT_BITS_DEFAULT |
| default ARCH_MMAP_RND_COMPAT_BITS_MIN |
| depends on HAVE_ARCH_MMAP_RND_COMPAT_BITS |
| help |
| This value can be used to select the number of bits to use to |
| determine the random offset to the base address of vma regions |
| resulting from mmap allocations for compatible applications This |
| value will be bounded by the architecture's minimum and maximum |
| supported values. |
| |
| This value can be changed after boot using the |
| /proc/sys/vm/mmap_rnd_compat_bits tunable |
| |
| config HAVE_ARCH_COMPAT_MMAP_BASES |
| bool |
| help |
| This allows 64bit applications to invoke 32-bit mmap() syscall |
| and vice-versa 32-bit applications to call 64-bit mmap(). |
| Required for applications doing different bitness syscalls. |
| |
| config PAGE_SIZE_LESS_THAN_64KB |
| def_bool y |
| depends on !ARM64_64K_PAGES |
| depends on !IA64_PAGE_SIZE_64KB |
| depends on !PAGE_SIZE_64KB |
| depends on !PARISC_PAGE_SIZE_64KB |
| depends on PAGE_SIZE_LESS_THAN_256KB |
| |
| config PAGE_SIZE_LESS_THAN_256KB |
| def_bool y |
| depends on !PAGE_SIZE_256KB |
| |
| # This allows to use a set of generic functions to determine mmap base |
| # address by giving priority to top-down scheme only if the process |
| # is not in legacy mode (compat task, unlimited stack size or |
| # sysctl_legacy_va_layout). |
| # Architecture that selects this option can provide its own version of: |
| # - STACK_RND_MASK |
| config ARCH_WANT_DEFAULT_TOPDOWN_MMAP_LAYOUT |
| bool |
| depends on MMU |
| select ARCH_HAS_ELF_RANDOMIZE |
| |
| config HAVE_OBJTOOL |
| bool |
| |
| config HAVE_JUMP_LABEL_HACK |
| bool |
| |
| config HAVE_NOINSTR_HACK |
| bool |
| |
| config HAVE_NOINSTR_VALIDATION |
| bool |
| |
| config HAVE_UACCESS_VALIDATION |
| bool |
| select OBJTOOL |
| |
| config HAVE_STACK_VALIDATION |
| bool |
| help |
| Architecture supports objtool compile-time frame pointer rule |
| validation. |
| |
| config HAVE_RELIABLE_STACKTRACE |
| bool |
| help |
| Architecture has either save_stack_trace_tsk_reliable() or |
| arch_stack_walk_reliable() function which only returns a stack trace |
| if it can guarantee the trace is reliable. |
| |
| config HAVE_ARCH_HASH |
| bool |
| default n |
| help |
| If this is set, the architecture provides an <asm/hash.h> |
| file which provides platform-specific implementations of some |
| functions in <linux/hash.h> or fs/namei.c. |
| |
| config HAVE_ARCH_NVRAM_OPS |
| bool |
| |
| config ISA_BUS_API |
| def_bool ISA |
| |
| # |
| # ABI hall of shame |
| # |
| config CLONE_BACKWARDS |
| bool |
| help |
| Architecture has tls passed as the 4th argument of clone(2), |
| not the 5th one. |
| |
| config CLONE_BACKWARDS2 |
| bool |
| help |
| Architecture has the first two arguments of clone(2) swapped. |
| |
| config CLONE_BACKWARDS3 |
| bool |
| help |
| Architecture has tls passed as the 3rd argument of clone(2), |
| not the 5th one. |
| |
| config ODD_RT_SIGACTION |
| bool |
| help |
| Architecture has unusual rt_sigaction(2) arguments |
| |
| config OLD_SIGSUSPEND |
| bool |
| help |
| Architecture has old sigsuspend(2) syscall, of one-argument variety |
| |
| config OLD_SIGSUSPEND3 |
| bool |
| help |
| Even weirder antique ABI - three-argument sigsuspend(2) |
| |
| config OLD_SIGACTION |
| bool |
| help |
| Architecture has old sigaction(2) syscall. Nope, not the same |
| as OLD_SIGSUSPEND | OLD_SIGSUSPEND3 - alpha has sigsuspend(2), |
| but fairly different variant of sigaction(2), thanks to OSF/1 |
| compatibility... |
| |
| config COMPAT_OLD_SIGACTION |
| bool |
| |
| config COMPAT_32BIT_TIME |
| bool "Provide system calls for 32-bit time_t" |
| default !64BIT || COMPAT |
| help |
| This enables 32 bit time_t support in addition to 64 bit time_t support. |
| This is relevant on all 32-bit architectures, and 64-bit architectures |
| as part of compat syscall handling. |
| |
| config ARCH_NO_PREEMPT |
| bool |
| |
| config ARCH_SUPPORTS_RT |
| bool |
| |
| config CPU_NO_EFFICIENT_FFS |
| def_bool n |
| |
| config HAVE_ARCH_VMAP_STACK |
| def_bool n |
| help |
| An arch should select this symbol if it can support kernel stacks |
| in vmalloc space. This means: |
| |
| - vmalloc space must be large enough to hold many kernel stacks. |
| This may rule out many 32-bit architectures. |
| |
| - Stacks in vmalloc space need to work reliably. For example, if |
| vmap page tables are created on demand, either this mechanism |
| needs to work while the stack points to a virtual address with |
| unpopulated page tables or arch code (switch_to() and switch_mm(), |
| most likely) needs to ensure that the stack's page table entries |
| are populated before running on a possibly unpopulated stack. |
| |
| - If the stack overflows into a guard page, something reasonable |
| should happen. The definition of "reasonable" is flexible, but |
| instantly rebooting without logging anything would be unfriendly. |
| |
| config VMAP_STACK |
| default y |
| bool "Use a virtually-mapped stack" |
| depends on HAVE_ARCH_VMAP_STACK |
| depends on !KASAN || KASAN_HW_TAGS || KASAN_VMALLOC |
| help |
| Enable this if you want the use virtually-mapped kernel stacks |
| with guard pages. This causes kernel stack overflows to be |
| caught immediately rather than causing difficult-to-diagnose |
| corruption. |
| |
| To use this with software KASAN modes, the architecture must support |
| backing virtual mappings with real shadow memory, and KASAN_VMALLOC |
| must be enabled. |
| |
| config HAVE_ARCH_RANDOMIZE_KSTACK_OFFSET |
| def_bool n |
| help |
| An arch should select this symbol if it can support kernel stack |
| offset randomization with calls to add_random_kstack_offset() |
| during syscall entry and choose_random_kstack_offset() during |
| syscall exit. Careful removal of -fstack-protector-strong and |
| -fstack-protector should also be applied to the entry code and |
| closely examined, as the artificial stack bump looks like an array |
| to the compiler, so it will attempt to add canary checks regardless |
| of the static branch state. |
| |
| config RANDOMIZE_KSTACK_OFFSET |
| bool "Support for randomizing kernel stack offset on syscall entry" if EXPERT |
| default y |
| depends on HAVE_ARCH_RANDOMIZE_KSTACK_OFFSET |
| depends on INIT_STACK_NONE || !CC_IS_CLANG || CLANG_VERSION >= 140000 |
| help |
| The kernel stack offset can be randomized (after pt_regs) by |
| roughly 5 bits of entropy, frustrating memory corruption |
| attacks that depend on stack address determinism or |
| cross-syscall address exposures. |
| |
| The feature is controlled via the "randomize_kstack_offset=on/off" |
| kernel boot param, and if turned off has zero overhead due to its use |
| of static branches (see JUMP_LABEL). |
| |
| If unsure, say Y. |
| |
| config RANDOMIZE_KSTACK_OFFSET_DEFAULT |
| bool "Default state of kernel stack offset randomization" |
| depends on RANDOMIZE_KSTACK_OFFSET |
| help |
| Kernel stack offset randomization is controlled by kernel boot param |
| "randomize_kstack_offset=on/off", and this config chooses the default |
| boot state. |
| |
| config ARCH_OPTIONAL_KERNEL_RWX |
| def_bool n |
| |
| config ARCH_OPTIONAL_KERNEL_RWX_DEFAULT |
| def_bool n |
| |
| config ARCH_HAS_STRICT_KERNEL_RWX |
| def_bool n |
| |
| config STRICT_KERNEL_RWX |
| bool "Make kernel text and rodata read-only" if ARCH_OPTIONAL_KERNEL_RWX |
| depends on ARCH_HAS_STRICT_KERNEL_RWX |
| default !ARCH_OPTIONAL_KERNEL_RWX || ARCH_OPTIONAL_KERNEL_RWX_DEFAULT |
| help |
| If this is set, kernel text and rodata memory will be made read-only, |
| and non-text memory will be made non-executable. This provides |
| protection against certain security exploits (e.g. executing the heap |
| or modifying text) |
| |
| These features are considered standard security practice these days. |
| You should say Y here in almost all cases. |
| |
| config ARCH_HAS_STRICT_MODULE_RWX |
| def_bool n |
| |
| config STRICT_MODULE_RWX |
| bool "Set loadable kernel module data as NX and text as RO" if ARCH_OPTIONAL_KERNEL_RWX |
| depends on ARCH_HAS_STRICT_MODULE_RWX && MODULES |
| default !ARCH_OPTIONAL_KERNEL_RWX || ARCH_OPTIONAL_KERNEL_RWX_DEFAULT |
| help |
| If this is set, module text and rodata memory will be made read-only, |
| and non-text memory will be made non-executable. This provides |
| protection against certain security exploits (e.g. writing to text) |
| |
| # select if the architecture provides an asm/dma-direct.h header |
| config ARCH_HAS_PHYS_TO_DMA |
| bool |
| |
| config HAVE_ARCH_COMPILER_H |
| bool |
| help |
| An architecture can select this if it provides an |
| asm/compiler.h header that should be included after |
| linux/compiler-*.h in order to override macro definitions that those |
| headers generally provide. |
| |
| config HAVE_ARCH_PREL32_RELOCATIONS |
| bool |
| help |
| May be selected by an architecture if it supports place-relative |
| 32-bit relocations, both in the toolchain and in the module loader, |
| in which case relative references can be used in special sections |
| for PCI fixup, initcalls etc which are only half the size on 64 bit |
| architectures, and don't require runtime relocation on relocatable |
| kernels. |
| |
| config ARCH_USE_MEMREMAP_PROT |
| bool |
| |
| config LOCK_EVENT_COUNTS |
| bool "Locking event counts collection" |
| depends on DEBUG_FS |
| help |
| Enable light-weight counting of various locking related events |
| in the system with minimal performance impact. This reduces |
| the chance of application behavior change because of timing |
| differences. The counts are reported via debugfs. |
| |
| # Select if the architecture has support for applying RELR relocations. |
| config ARCH_HAS_RELR |
| bool |
| |
| config RELR |
| bool "Use RELR relocation packing" |
| depends on ARCH_HAS_RELR && TOOLS_SUPPORT_RELR |
| default y |
| help |
| Store the kernel's dynamic relocations in the RELR relocation packing |
| format. Requires a compatible linker (LLD supports this feature), as |
| well as compatible NM and OBJCOPY utilities (llvm-nm and llvm-objcopy |
| are compatible). |
| |
| config ARCH_HAS_MEM_ENCRYPT |
| bool |
| |
| config ARCH_HAS_CC_PLATFORM |
| bool |
| |
| config HAVE_SPARSE_SYSCALL_NR |
| bool |
| help |
| An architecture should select this if its syscall numbering is sparse |
| to save space. For example, MIPS architecture has a syscall array with |
| entries at 4000, 5000 and 6000 locations. This option turns on syscall |
| related optimizations for a given architecture. |
| |
| config ARCH_HAS_VDSO_DATA |
| bool |
| |
| config HAVE_STATIC_CALL |
| bool |
| |
| config HAVE_STATIC_CALL_INLINE |
| bool |
| depends on HAVE_STATIC_CALL |
| select OBJTOOL |
| |
| config HAVE_PREEMPT_DYNAMIC |
| bool |
| |
| config HAVE_PREEMPT_DYNAMIC_CALL |
| bool |
| depends on HAVE_STATIC_CALL |
| select HAVE_PREEMPT_DYNAMIC |
| help |
| An architecture should select this if it can handle the preemption |
| model being selected at boot time using static calls. |
| |
| Where an architecture selects HAVE_STATIC_CALL_INLINE, any call to a |
| preemption function will be patched directly. |
| |
| Where an architecture does not select HAVE_STATIC_CALL_INLINE, any |
| call to a preemption function will go through a trampoline, and the |
| trampoline will be patched. |
| |
| It is strongly advised to support inline static call to avoid any |
| overhead. |
| |
| config HAVE_PREEMPT_DYNAMIC_KEY |
| bool |
| depends on HAVE_ARCH_JUMP_LABEL |
| select HAVE_PREEMPT_DYNAMIC |
| help |
| An architecture should select this if it can handle the preemption |
| model being selected at boot time using static keys. |
| |
| Each preemption function will be given an early return based on a |
| static key. This should have slightly lower overhead than non-inline |
| static calls, as this effectively inlines each trampoline into the |
| start of its callee. This may avoid redundant work, and may |
| integrate better with CFI schemes. |
| |
| This will have greater overhead than using inline static calls as |
| the call to the preemption function cannot be entirely elided. |
| |
| config ARCH_WANT_LD_ORPHAN_WARN |
| bool |
| help |
| An arch should select this symbol once all linker sections are explicitly |
| included, size-asserted, or discarded in the linker scripts. This is |
| important because we never want expected sections to be placed heuristically |
| by the linker, since the locations of such sections can change between linker |
| versions. |
| |
| config HAVE_ARCH_PFN_VALID |
| bool |
| |
| config ARCH_SUPPORTS_DEBUG_PAGEALLOC |
| bool |
| |
| config ARCH_SUPPORTS_PAGE_TABLE_CHECK |
| bool |
| |
| config ARCH_SPLIT_ARG64 |
| bool |
| help |
| If a 32-bit architecture requires 64-bit arguments to be split into |
| pairs of 32-bit arguments, select this option. |
| |
| config ARCH_HAS_ELFCORE_COMPAT |
| bool |
| |
| config ARCH_HAS_PARANOID_L1D_FLUSH |
| bool |
| |
| config ARCH_HAVE_TRACE_MMIO_ACCESS |
| bool |
| |
| config DYNAMIC_SIGFRAME |
| bool |
| |
| # Select, if arch has a named attribute group bound to NUMA device nodes. |
| config HAVE_ARCH_NODE_DEV_GROUP |
| bool |
| |
| config ARCH_HAS_NONLEAF_PMD_YOUNG |
| bool |
| help |
| Architectures that select this option are capable of setting the |
| accessed bit in non-leaf PMD entries when using them as part of linear |
| address translations. Page table walkers that clear the accessed bit |
| may use this capability to reduce their search space. |
| |
| source "kernel/gcov/Kconfig" |
| |
| source "scripts/gcc-plugins/Kconfig" |
| |
| config FUNCTION_ALIGNMENT_4B |
| bool |
| |
| config FUNCTION_ALIGNMENT_8B |
| bool |
| |
| config FUNCTION_ALIGNMENT_16B |
| bool |
| |
| config FUNCTION_ALIGNMENT_32B |
| bool |
| |
| config FUNCTION_ALIGNMENT_64B |
| bool |
| |
| config FUNCTION_ALIGNMENT |
| int |
| default 64 if FUNCTION_ALIGNMENT_64B |
| default 32 if FUNCTION_ALIGNMENT_32B |
| default 16 if FUNCTION_ALIGNMENT_16B |
| default 8 if FUNCTION_ALIGNMENT_8B |
| default 4 if FUNCTION_ALIGNMENT_4B |
| default 0 |
| |
| endmenu |