mirror of
https://github.com/torvalds/linux.git
synced 2024-11-29 23:51:37 +00:00
70e6e1b971
Pull CONFIG_PREEMPT_RT stub config from Thomas Gleixner:
"The real-time preemption patch set exists for almost 15 years now and
while the vast majority of infrastructure and enhancements have found
their way into the mainline kernel, the final integration of RT is
still missing.
Over the course of the last few years, we have worked on reducing the
intrusivenness of the RT patches by refactoring kernel infrastructure
to be more real-time friendly. Almost all of these changes were
benefitial to the mainline kernel on their own, so there was no
objection to integrate them.
Though except for the still ongoing printk refactoring, the remaining
changes which are required to make RT a first class mainline citizen
are not longer arguable as immediately beneficial for the mainline
kernel. Most of them are either reordering code flows or adding RT
specific functionality.
But this now has hit a wall and turned into a classic hen and egg
problem:
Maintainers are rightfully wary vs. these changes as they make only
sense if the final integration of RT into the mainline kernel takes
place.
Adding CONFIG_PREEMPT_RT aims to solve this as a clear sign that RT
will be fully integrated into the mainline kernel. The final
integration of the missing bits and pieces will be of course done with
the same careful approach as we have used in the past.
While I'm aware that you are not entirely enthusiastic about that, I
think that RT should receive the same treatment as any other widely
used out of tree functionality, which we have accepted into mainline
over the years.
RT has become the de-facto standard real-time enhancement and is
shipped by enterprise, embedded and community distros. It's in use
throughout a wide range of industries: telecommunications, industrial
automation, professional audio, medical devices, data acquisition,
automotive - just to name a few major use cases.
RT development is backed by a Linuxfoundation project which is
supported by major stakeholders of this technology. The funding will
continue over the actual inclusion into mainline to make sure that the
functionality is neither introducing regressions, regressing itself,
nor becomes subject to bitrot. There is also a lifely user community
around RT as well, so contrary to the grim situation 5 years ago, it's
a healthy project.
As RT is still a good vehicle to exercise rarely used code paths and
to detect hard to trigger issues, you could at least view it as a QA
tool if nothing else"
* 'sched-urgent-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip:
sched/rt, Kconfig: Introduce CONFIG_PREEMPT_RT
933 lines
27 KiB
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933 lines
27 KiB
Plaintext
# SPDX-License-Identifier: GPL-2.0
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#
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# General architecture dependent options
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#
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#
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# Note: arch/$(SRCARCH)/Kconfig needs to be included first so that it can
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# override the default values in this file.
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#
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source "arch/$(SRCARCH)/Kconfig"
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menu "General architecture-dependent options"
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config CRASH_CORE
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bool
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config KEXEC_CORE
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select CRASH_CORE
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bool
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config HAVE_IMA_KEXEC
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bool
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config HOTPLUG_SMT
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bool
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config OPROFILE
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tristate "OProfile system profiling"
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depends on PROFILING
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depends on HAVE_OPROFILE
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select RING_BUFFER
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select RING_BUFFER_ALLOW_SWAP
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help
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OProfile is a profiling system capable of profiling the
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whole system, include the kernel, kernel modules, libraries,
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and applications.
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If unsure, say N.
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config OPROFILE_EVENT_MULTIPLEX
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bool "OProfile multiplexing support (EXPERIMENTAL)"
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default n
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depends on OPROFILE && X86
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help
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The number of hardware counters is limited. The multiplexing
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feature enables OProfile to gather more events than counters
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are provided by the hardware. This is realized by switching
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between events at a user specified time interval.
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If unsure, say N.
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config HAVE_OPROFILE
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bool
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config OPROFILE_NMI_TIMER
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def_bool y
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depends on PERF_EVENTS && HAVE_PERF_EVENTS_NMI && !PPC64
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config KPROBES
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bool "Kprobes"
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depends on MODULES
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depends on HAVE_KPROBES
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select KALLSYMS
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help
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Kprobes allows you to trap at almost any kernel address and
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execute a callback function. register_kprobe() establishes
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a probepoint and specifies the callback. Kprobes is useful
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for kernel debugging, non-intrusive instrumentation and testing.
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If in doubt, say "N".
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config JUMP_LABEL
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bool "Optimize very unlikely/likely branches"
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depends on HAVE_ARCH_JUMP_LABEL
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depends on CC_HAS_ASM_GOTO
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help
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This option enables a transparent branch optimization that
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makes certain almost-always-true or almost-always-false branch
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conditions even cheaper to execute within the kernel.
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Certain performance-sensitive kernel code, such as trace points,
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scheduler functionality, networking code and KVM have such
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branches and include support for this optimization technique.
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If it is detected that the compiler has support for "asm goto",
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the kernel will compile such branches with just a nop
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instruction. When the condition flag is toggled to true, the
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nop will be converted to a jump instruction to execute the
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conditional block of instructions.
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This technique lowers overhead and stress on the branch prediction
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of the processor and generally makes the kernel faster. The update
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of the condition is slower, but those are always very rare.
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( On 32-bit x86, the necessary options added to the compiler
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flags may increase the size of the kernel slightly. )
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config STATIC_KEYS_SELFTEST
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bool "Static key selftest"
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depends on JUMP_LABEL
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help
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Boot time self-test of the branch patching code.
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config OPTPROBES
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def_bool y
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depends on KPROBES && HAVE_OPTPROBES
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select TASKS_RCU if PREEMPT
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config KPROBES_ON_FTRACE
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def_bool y
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depends on KPROBES && HAVE_KPROBES_ON_FTRACE
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depends on DYNAMIC_FTRACE_WITH_REGS
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help
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If function tracer is enabled and the arch supports full
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passing of pt_regs to function tracing, then kprobes can
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optimize on top of function tracing.
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config UPROBES
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def_bool n
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depends on ARCH_SUPPORTS_UPROBES
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help
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Uprobes is the user-space counterpart to kprobes: they
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enable instrumentation applications (such as 'perf probe')
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to establish unintrusive probes in user-space binaries and
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libraries, by executing handler functions when the probes
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are hit by user-space applications.
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( These probes come in the form of single-byte breakpoints,
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managed by the kernel and kept transparent to the probed
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application. )
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config HAVE_EFFICIENT_UNALIGNED_ACCESS
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bool
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help
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Some architectures are unable to perform unaligned accesses
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without the use of get_unaligned/put_unaligned. Others are
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unable to perform such accesses efficiently (e.g. trap on
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unaligned access and require fixing it up in the exception
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handler.)
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This symbol should be selected by an architecture if it can
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perform unaligned accesses efficiently to allow different
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code paths to be selected for these cases. Some network
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drivers, for example, could opt to not fix up alignment
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problems with received packets if doing so would not help
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much.
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See Documentation/unaligned-memory-access.txt for more
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information on the topic of unaligned memory accesses.
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config ARCH_USE_BUILTIN_BSWAP
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bool
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help
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Modern versions of GCC (since 4.4) have builtin functions
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for handling byte-swapping. Using these, instead of the old
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inline assembler that the architecture code provides in the
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__arch_bswapXX() macros, allows the compiler to see what's
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happening and offers more opportunity for optimisation. In
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particular, the compiler will be able to combine the byteswap
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with a nearby load or store and use load-and-swap or
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store-and-swap instructions if the architecture has them. It
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should almost *never* result in code which is worse than the
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hand-coded assembler in <asm/swab.h>. But just in case it
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does, the use of the builtins is optional.
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Any architecture with load-and-swap or store-and-swap
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instructions should set this. And it shouldn't hurt to set it
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on architectures that don't have such instructions.
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config KRETPROBES
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def_bool y
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depends on KPROBES && HAVE_KRETPROBES
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config USER_RETURN_NOTIFIER
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bool
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depends on HAVE_USER_RETURN_NOTIFIER
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help
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Provide a kernel-internal notification when a cpu is about to
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switch to user mode.
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config HAVE_IOREMAP_PROT
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bool
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config HAVE_KPROBES
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bool
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config HAVE_KRETPROBES
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bool
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config HAVE_OPTPROBES
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bool
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config HAVE_KPROBES_ON_FTRACE
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bool
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config HAVE_FUNCTION_ERROR_INJECTION
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bool
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config HAVE_NMI
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bool
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#
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# An arch should select this if it provides all these things:
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#
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# task_pt_regs() in asm/processor.h or asm/ptrace.h
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# arch_has_single_step() if there is hardware single-step support
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# arch_has_block_step() if there is hardware block-step support
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# asm/syscall.h supplying asm-generic/syscall.h interface
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# linux/regset.h user_regset interfaces
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# CORE_DUMP_USE_REGSET #define'd in linux/elf.h
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# TIF_SYSCALL_TRACE calls tracehook_report_syscall_{entry,exit}
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# TIF_NOTIFY_RESUME calls tracehook_notify_resume()
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# signal delivery calls tracehook_signal_handler()
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#
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config HAVE_ARCH_TRACEHOOK
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bool
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config HAVE_DMA_CONTIGUOUS
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bool
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config GENERIC_SMP_IDLE_THREAD
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bool
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config GENERIC_IDLE_POLL_SETUP
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bool
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config ARCH_HAS_FORTIFY_SOURCE
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bool
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help
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An architecture should select this when it can successfully
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build and run with CONFIG_FORTIFY_SOURCE.
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#
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# Select if the arch provides a historic keepinit alias for the retain_initrd
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# command line option
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#
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config ARCH_HAS_KEEPINITRD
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bool
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# Select if arch has all set_memory_ro/rw/x/nx() functions in asm/cacheflush.h
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config ARCH_HAS_SET_MEMORY
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bool
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# Select if arch has all set_direct_map_invalid/default() functions
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config ARCH_HAS_SET_DIRECT_MAP
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bool
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#
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# Select if arch has an uncached kernel segment and provides the
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# uncached_kernel_address / cached_kernel_address symbols to use it
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#
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config ARCH_HAS_UNCACHED_SEGMENT
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select ARCH_HAS_DMA_PREP_COHERENT
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bool
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# Select if arch init_task must go in the __init_task_data section
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config ARCH_TASK_STRUCT_ON_STACK
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bool
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# Select if arch has its private alloc_task_struct() function
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config ARCH_TASK_STRUCT_ALLOCATOR
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bool
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config HAVE_ARCH_THREAD_STRUCT_WHITELIST
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bool
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depends on !ARCH_TASK_STRUCT_ALLOCATOR
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help
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An architecture should select this to provide hardened usercopy
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knowledge about what region of the thread_struct should be
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whitelisted for copying to userspace. Normally this is only the
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FPU registers. Specifically, arch_thread_struct_whitelist()
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should be implemented. Without this, the entire thread_struct
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field in task_struct will be left whitelisted.
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# Select if arch has its private alloc_thread_stack() function
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config ARCH_THREAD_STACK_ALLOCATOR
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bool
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# Select if arch wants to size task_struct dynamically via arch_task_struct_size:
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config ARCH_WANTS_DYNAMIC_TASK_STRUCT
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bool
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config ARCH_32BIT_OFF_T
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bool
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depends on !64BIT
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help
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All new 32-bit architectures should have 64-bit off_t type on
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userspace side which corresponds to the loff_t kernel type. This
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is the requirement for modern ABIs. Some existing architectures
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still support 32-bit off_t. This option is enabled for all such
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architectures explicitly.
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config HAVE_REGS_AND_STACK_ACCESS_API
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bool
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help
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This symbol should be selected by an architecure if it supports
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the API needed to access registers and stack entries from pt_regs,
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declared in asm/ptrace.h
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For example the kprobes-based event tracer needs this API.
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config HAVE_RSEQ
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bool
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depends on HAVE_REGS_AND_STACK_ACCESS_API
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help
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This symbol should be selected by an architecture if it
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supports an implementation of restartable sequences.
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config HAVE_FUNCTION_ARG_ACCESS_API
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bool
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help
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This symbol should be selected by an architecure if it supports
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the API needed to access function arguments from pt_regs,
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declared in asm/ptrace.h
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config HAVE_CLK
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bool
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help
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The <linux/clk.h> calls support software clock gating and
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thus are a key power management tool on many systems.
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config HAVE_HW_BREAKPOINT
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bool
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depends on PERF_EVENTS
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config HAVE_MIXED_BREAKPOINTS_REGS
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bool
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depends on HAVE_HW_BREAKPOINT
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help
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Depending on the arch implementation of hardware breakpoints,
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some of them have separate registers for data and instruction
|
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breakpoints addresses, others have mixed registers to store
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them but define the access type in a control register.
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Select this option if your arch implements breakpoints under the
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latter fashion.
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config HAVE_USER_RETURN_NOTIFIER
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bool
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config HAVE_PERF_EVENTS_NMI
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bool
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help
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System hardware can generate an NMI using the perf event
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subsystem. Also has support for calculating CPU cycle events
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to determine how many clock cycles in a given period.
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config HAVE_HARDLOCKUP_DETECTOR_PERF
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bool
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depends on HAVE_PERF_EVENTS_NMI
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help
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The arch chooses to use the generic perf-NMI-based hardlockup
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detector. Must define HAVE_PERF_EVENTS_NMI.
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config HAVE_NMI_WATCHDOG
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depends on HAVE_NMI
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bool
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help
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The arch provides a low level NMI watchdog. It provides
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asm/nmi.h, and defines its own arch_touch_nmi_watchdog().
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config HAVE_HARDLOCKUP_DETECTOR_ARCH
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bool
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select HAVE_NMI_WATCHDOG
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help
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The arch chooses to provide its own hardlockup detector, which is
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a superset of the HAVE_NMI_WATCHDOG. It also conforms to config
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interfaces and parameters provided by hardlockup detector subsystem.
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config HAVE_PERF_REGS
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bool
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help
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Support selective register dumps for perf events. This includes
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bit-mapping of each registers and a unique architecture id.
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config HAVE_PERF_USER_STACK_DUMP
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bool
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help
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Support user stack dumps for perf event samples. This needs
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access to the user stack pointer which is not unified across
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architectures.
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config HAVE_ARCH_JUMP_LABEL
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bool
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config HAVE_ARCH_JUMP_LABEL_RELATIVE
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bool
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config HAVE_RCU_TABLE_FREE
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bool
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config HAVE_RCU_TABLE_NO_INVALIDATE
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bool
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config HAVE_MMU_GATHER_PAGE_SIZE
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bool
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config HAVE_MMU_GATHER_NO_GATHER
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bool
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config ARCH_HAVE_NMI_SAFE_CMPXCHG
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bool
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config HAVE_ALIGNED_STRUCT_PAGE
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bool
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help
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This makes sure that struct pages are double word aligned and that
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e.g. the SLUB allocator can perform double word atomic operations
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on a struct page for better performance. However selecting this
|
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might increase the size of a struct page by a word.
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config HAVE_CMPXCHG_LOCAL
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bool
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config HAVE_CMPXCHG_DOUBLE
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bool
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config ARCH_WEAK_RELEASE_ACQUIRE
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bool
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config ARCH_WANT_IPC_PARSE_VERSION
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bool
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config ARCH_WANT_COMPAT_IPC_PARSE_VERSION
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bool
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config ARCH_WANT_OLD_COMPAT_IPC
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select ARCH_WANT_COMPAT_IPC_PARSE_VERSION
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bool
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config HAVE_ARCH_SECCOMP_FILTER
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bool
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help
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An arch should select this symbol if it provides all of these things:
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- syscall_get_arch()
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- syscall_get_arguments()
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- syscall_rollback()
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- syscall_set_return_value()
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- SIGSYS siginfo_t support
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- secure_computing is called from a ptrace_event()-safe context
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- secure_computing return value is checked and a return value of -1
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results in the system call being skipped immediately.
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- seccomp syscall wired up
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|
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config SECCOMP_FILTER
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def_bool y
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depends on HAVE_ARCH_SECCOMP_FILTER && SECCOMP && NET
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help
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|
Enable tasks to build secure computing environments defined
|
|
in terms of Berkeley Packet Filter programs which implement
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task-defined system call filtering polices.
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|
|
See Documentation/userspace-api/seccomp_filter.rst for details.
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|
|
config HAVE_ARCH_STACKLEAK
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bool
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|
help
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|
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
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|
bool
|
|
help
|
|
An arch should select this symbol if:
|
|
- it has implemented a stack canary (e.g. __stack_chk_guard)
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|
|
config CC_HAS_STACKPROTECTOR_NONE
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|
def_bool $(cc-option,-fno-stack-protector)
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|
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config STACKPROTECTOR
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bool "Stack Protector buffer overflow detection"
|
|
depends on HAVE_STACKPROTECTOR
|
|
depends on $(cc-option,-fstack-protector)
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|
default y
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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
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neutralized via a kernel panic.
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|
|
Functions will have the stack-protector canary logic added if they
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|
have an 8-byte or larger character array on the stack.
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This feature requires gcc version 4.2 or above, or a distribution
|
|
gcc with the feature backported ("-fstack-protector").
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|
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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%.
|
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|
|
config STACKPROTECTOR_STRONG
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|
bool "Strong Stack Protector"
|
|
depends on STACKPROTECTOR
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|
depends on $(cc-option,-fstack-protector-strong)
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|
default y
|
|
help
|
|
Functions will have the stack-protector canary logic added in any
|
|
of the following conditions:
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|
|
|
- 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
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|
|
This feature requires gcc version 4.9 or above, or a distribution
|
|
gcc with the feature backported ("-fstack-protector-strong").
|
|
|
|
On an x86 "defconfig" build, this feature adds canary checks to
|
|
about 20% of all kernel functions, which increases the kernel code
|
|
size by about 2%.
|
|
|
|
config HAVE_ARCH_WITHIN_STACK_FRAMES
|
|
bool
|
|
help
|
|
An architecture should select this if it can walk the kernel stack
|
|
frames to determine if an object is part of either the arguments
|
|
or local variables (i.e. that it excludes saved return addresses,
|
|
and similar) by implementing an inline arch_within_stack_frames(),
|
|
which is used by CONFIG_HARDENED_USERCOPY.
|
|
|
|
config HAVE_CONTEXT_TRACKING
|
|
bool
|
|
help
|
|
Provide kernel/user boundaries probes necessary for subsystems
|
|
that need it, such as userspace RCU extended quiescent state.
|
|
Syscalls need to be wrapped inside user_exit()-user_enter() through
|
|
the slow path using TIF_NOHZ flag. Exceptions handlers must be
|
|
wrapped as well. Irqs are already protected inside
|
|
rcu_irq_enter/rcu_irq_exit() but preemption or signal handling on
|
|
irq exit still need to be protected.
|
|
|
|
config HAVE_VIRT_CPU_ACCOUNTING
|
|
bool
|
|
|
|
config ARCH_HAS_SCALED_CPUTIME
|
|
bool
|
|
|
|
config HAVE_VIRT_CPU_ACCOUNTING_GEN
|
|
bool
|
|
default y if 64BIT
|
|
help
|
|
With VIRT_CPU_ACCOUNTING_GEN, cputime_t becomes 64-bit.
|
|
Before enabling this option, arch code must be audited
|
|
to ensure there are no races in concurrent read/write of
|
|
cputime_t. For example, reading/writing 64-bit cputime_t on
|
|
some 32-bit arches may require multiple accesses, so proper
|
|
locking is needed to protect against concurrent accesses.
|
|
|
|
|
|
config HAVE_IRQ_TIME_ACCOUNTING
|
|
bool
|
|
help
|
|
Archs need to ensure they use a high enough resolution clock to
|
|
support irq time accounting and then call enable_sched_clock_irqtime().
|
|
|
|
config HAVE_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.
|
|
|
|
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_COHERENT_DMA_MMAP
|
|
bool
|
|
|
|
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 ARCH_HAS_REFCOUNT
|
|
bool
|
|
help
|
|
An architecture selects this when it has implemented refcount_t
|
|
using open coded assembly primitives that provide an optimized
|
|
refcount_t implementation, possibly at the expense of some full
|
|
refcount state checks of CONFIG_REFCOUNT_FULL=y.
|
|
|
|
The refcount overflow check behavior, however, must be retained.
|
|
Catching overflows is the primary security concern for protecting
|
|
against bugs in reference counts.
|
|
|
|
config REFCOUNT_FULL
|
|
bool "Perform full reference count validation at the expense of speed"
|
|
help
|
|
Enabling this switches the refcounting infrastructure from a fast
|
|
unchecked atomic_t implementation to a fully state checked
|
|
implementation, which can be (slightly) slower but provides protections
|
|
against various use-after-free conditions that can be used in
|
|
security flaw exploits.
|
|
|
|
config HAVE_ARCH_COMPILER_H
|
|
bool
|
|
help
|
|
An architecture can select this if it provides an
|
|
asm/compiler.h header that should be included after
|
|
linux/compiler-*.h in order to override macro definitions that those
|
|
headers generally provide.
|
|
|
|
config HAVE_ARCH_PREL32_RELOCATIONS
|
|
bool
|
|
help
|
|
May be selected by an architecture if it supports place-relative
|
|
32-bit relocations, both in the toolchain and in the module loader,
|
|
in which case relative references can be used in special sections
|
|
for PCI fixup, initcalls etc which are only half the size on 64 bit
|
|
architectures, and don't require runtime relocation on relocatable
|
|
kernels.
|
|
|
|
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.
|
|
|
|
source "kernel/gcov/Kconfig"
|
|
|
|
source "scripts/gcc-plugins/Kconfig"
|
|
|
|
endmenu
|