bool
config GENERIC_ENTRY
- bool
+ bool
config KPROBES
bool "Kprobes"
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.
+ 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.
+ 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.
+ 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.
+ 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. )
+ ( 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 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.
+ 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
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.
+ 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.
+ 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 !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:
+ 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
bool
config HAVE_SPARSE_SYSCALL_NR
- bool
- help
- An architecture should select this if its syscall numbering is sparse
+ 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.
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.
+ 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 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.
+ 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.
+ 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.
+ 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.
+ 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.
+ 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
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.
+ 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
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