230 lines
8.3 KiB
Plaintext
230 lines
8.3 KiB
Plaintext
preferred-plugin-hostcc := $(if-success,[ $(gcc-version) -ge 40800 ],$(HOSTCXX),$(HOSTCC))
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config PLUGIN_HOSTCC
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string
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default "$(shell,$(srctree)/scripts/gcc-plugin.sh "$(preferred-plugin-hostcc)" "$(HOSTCXX)" "$(CC)")" if CC_IS_GCC
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help
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Host compiler used to build GCC plugins. This can be $(HOSTCXX),
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$(HOSTCC), or a null string if GCC plugin is unsupported.
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config HAVE_GCC_PLUGINS
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bool
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help
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An arch should select this symbol if it supports building with
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GCC plugins.
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menuconfig GCC_PLUGINS
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bool "GCC plugins"
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depends on HAVE_GCC_PLUGINS
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depends on PLUGIN_HOSTCC != ""
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help
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GCC plugins are loadable modules that provide extra features to the
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compiler. They are useful for runtime instrumentation and static analysis.
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See Documentation/gcc-plugins.txt for details.
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if GCC_PLUGINS
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config GCC_PLUGIN_CYC_COMPLEXITY
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bool "Compute the cyclomatic complexity of a function" if EXPERT
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depends on !COMPILE_TEST # too noisy
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help
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The complexity M of a function's control flow graph is defined as:
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M = E - N + 2P
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where
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E = the number of edges
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N = the number of nodes
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P = the number of connected components (exit nodes).
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Enabling this plugin reports the complexity to stderr during the
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build. It mainly serves as a simple example of how to create a
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gcc plugin for the kernel.
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config GCC_PLUGIN_SANCOV
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bool
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help
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This plugin inserts a __sanitizer_cov_trace_pc() call at the start of
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basic blocks. It supports all gcc versions with plugin support (from
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gcc-4.5 on). It is based on the commit "Add fuzzing coverage support"
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by Dmitry Vyukov <dvyukov@google.com>.
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config GCC_PLUGIN_LATENT_ENTROPY
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bool "Generate some entropy during boot and runtime"
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help
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By saying Y here the kernel will instrument some kernel code to
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extract some entropy from both original and artificially created
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program state. This will help especially embedded systems where
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there is little 'natural' source of entropy normally. The cost
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is some slowdown of the boot process (about 0.5%) and fork and
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irq processing.
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Note that entropy extracted this way is not cryptographically
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secure!
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This plugin was ported from grsecurity/PaX. More information at:
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* https://grsecurity.net/
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* https://pax.grsecurity.net/
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config GCC_PLUGIN_STRUCTLEAK
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bool "Zero initialize stack variables"
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help
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While the kernel is built with warnings enabled for any missed
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stack variable initializations, this warning is silenced for
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anything passed by reference to another function, under the
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occasionally misguided assumption that the function will do
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the initialization. As this regularly leads to exploitable
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flaws, this plugin is available to identify and zero-initialize
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such variables, depending on the chosen level of coverage.
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This plugin was originally ported from grsecurity/PaX. More
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information at:
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* https://grsecurity.net/
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* https://pax.grsecurity.net/
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choice
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prompt "Coverage"
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depends on GCC_PLUGIN_STRUCTLEAK
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default GCC_PLUGIN_STRUCTLEAK_BYREF_ALL
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help
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This chooses the level of coverage over classes of potentially
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uninitialized variables. The selected class will be
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zero-initialized before use.
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config GCC_PLUGIN_STRUCTLEAK_USER
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bool "structs marked for userspace"
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help
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Zero-initialize any structures on the stack containing
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a __user attribute. This can prevent some classes of
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uninitialized stack variable exploits and information
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exposures, like CVE-2013-2141:
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https://git.kernel.org/linus/b9e146d8eb3b9eca
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config GCC_PLUGIN_STRUCTLEAK_BYREF
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bool "structs passed by reference"
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help
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Zero-initialize any structures on the stack that may
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be passed by reference and had not already been
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explicitly initialized. This can prevent most classes
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of uninitialized stack variable exploits and information
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exposures, like CVE-2017-1000410:
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https://git.kernel.org/linus/06e7e776ca4d3654
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config GCC_PLUGIN_STRUCTLEAK_BYREF_ALL
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bool "anything passed by reference"
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help
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Zero-initialize any stack variables that may be passed
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by reference and had not already been explicitly
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initialized. This is intended to eliminate all classes
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of uninitialized stack variable exploits and information
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exposures.
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endchoice
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config GCC_PLUGIN_STRUCTLEAK_VERBOSE
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bool "Report forcefully initialized variables"
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depends on GCC_PLUGIN_STRUCTLEAK
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depends on !COMPILE_TEST # too noisy
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help
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This option will cause a warning to be printed each time the
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structleak plugin finds a variable it thinks needs to be
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initialized. Since not all existing initializers are detected
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by the plugin, this can produce false positive warnings.
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config GCC_PLUGIN_RANDSTRUCT
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bool "Randomize layout of sensitive kernel structures"
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select MODVERSIONS if MODULES
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help
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If you say Y here, the layouts of structures that are entirely
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function pointers (and have not been manually annotated with
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__no_randomize_layout), or structures that have been explicitly
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marked with __randomize_layout, will be randomized at compile-time.
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This can introduce the requirement of an additional information
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exposure vulnerability for exploits targeting these structure
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types.
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Enabling this feature will introduce some performance impact,
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slightly increase memory usage, and prevent the use of forensic
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tools like Volatility against the system (unless the kernel
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source tree isn't cleaned after kernel installation).
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The seed used for compilation is located at
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scripts/gcc-plgins/randomize_layout_seed.h. It remains after
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a make clean to allow for external modules to be compiled with
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the existing seed and will be removed by a make mrproper or
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make distclean.
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Note that the implementation requires gcc 4.7 or newer.
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This plugin was ported from grsecurity/PaX. More information at:
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* https://grsecurity.net/
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* https://pax.grsecurity.net/
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config GCC_PLUGIN_RANDSTRUCT_PERFORMANCE
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bool "Use cacheline-aware structure randomization"
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depends on GCC_PLUGIN_RANDSTRUCT
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depends on !COMPILE_TEST # do not reduce test coverage
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help
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If you say Y here, the RANDSTRUCT randomization will make a
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best effort at restricting randomization to cacheline-sized
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groups of elements. It will further not randomize bitfields
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in structures. This reduces the performance hit of RANDSTRUCT
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at the cost of weakened randomization.
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config GCC_PLUGIN_STACKLEAK
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bool "Erase the kernel stack before returning from syscalls"
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depends on GCC_PLUGINS
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depends on HAVE_ARCH_STACKLEAK
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help
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This option makes the kernel erase the kernel stack before
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returning from system calls. That reduces the information which
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kernel stack leak bugs can reveal and blocks some uninitialized
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stack variable attacks.
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The tradeoff is the performance impact: on a single CPU system kernel
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compilation sees a 1% slowdown, other systems and workloads may vary
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and you are advised to test this feature on your expected workload
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before deploying it.
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This plugin was ported from grsecurity/PaX. More information at:
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* https://grsecurity.net/
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* https://pax.grsecurity.net/
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config STACKLEAK_TRACK_MIN_SIZE
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int "Minimum stack frame size of functions tracked by STACKLEAK"
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default 100
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range 0 4096
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depends on GCC_PLUGIN_STACKLEAK
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help
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The STACKLEAK gcc plugin instruments the kernel code for tracking
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the lowest border of the kernel stack (and for some other purposes).
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It inserts the stackleak_track_stack() call for the functions with
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a stack frame size greater than or equal to this parameter.
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If unsure, leave the default value 100.
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config STACKLEAK_METRICS
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bool "Show STACKLEAK metrics in the /proc file system"
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depends on GCC_PLUGIN_STACKLEAK
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depends on PROC_FS
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help
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If this is set, STACKLEAK metrics for every task are available in
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the /proc file system. In particular, /proc/<pid>/stack_depth
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shows the maximum kernel stack consumption for the current and
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previous syscalls. Although this information is not precise, it
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can be useful for estimating the STACKLEAK performance impact for
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your workloads.
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config STACKLEAK_RUNTIME_DISABLE
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bool "Allow runtime disabling of kernel stack erasing"
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depends on GCC_PLUGIN_STACKLEAK
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help
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This option provides 'stack_erasing' sysctl, which can be used in
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runtime to control kernel stack erasing for kernels built with
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CONFIG_GCC_PLUGIN_STACKLEAK.
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config GCC_PLUGIN_ARM_SSP_PER_TASK
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bool
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depends on GCC_PLUGINS && ARM
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endif
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