lib/Kconfig.kasan

config HAVE_ARCH_KASAN
	bool

if HAVE_ARCH_KASAN

config KASAN
	bool "KASan: runtime memory debugger"
	depends on (SLUB && SYSFS) || (SLAB && !DEBUG_SLAB)
	select SLUB_DEBUG if SLUB
	select CONSTRUCTORS
	select STACKDEPOT
	help
	  Enables kernel address sanitizer - runtime memory debugger,
	  designed to find out-of-bounds accesses and use-after-free bugs.
	  This is strictly a debugging feature and it requires a gcc version
	  of 4.9.2 or later. Detection of out of bounds accesses to stack or
	  global variables requires gcc 5.0 or later.
	  This feature consumes about 1/8 of available memory and brings about
	  ~x3 performance slowdown.
	  For better error detection enable CONFIG_STACKTRACE.
	  Currently CONFIG_KASAN doesn't work with CONFIG_DEBUG_SLAB
	  (the resulting kernel does not boot).

config KASAN_EXTRA
	bool "KAsan: extra checks"
	depends on KASAN && DEBUG_KERNEL && !COMPILE_TEST
	help
	  This enables further checks in the kernel address sanitizer, for now
	  it only includes the address-use-after-scope check that can lead
	  to excessive kernel stack usage, frame size warnings and longer
	  compile time.
	  https://gcc.gnu.org/bugzilla/show_bug.cgi?id=81715 has more


choice
	prompt "Instrumentation type"
	depends on KASAN
	default KASAN_OUTLINE

config KASAN_OUTLINE
	bool "Outline instrumentation"
	help
	  Before every memory access compiler insert function call
	  __asan_load*/__asan_store*. These functions performs check
	  of shadow memory. This is slower than inline instrumentation,
	  however it doesn't bloat size of kernel's .text section so
	  much as inline does.

config KASAN_INLINE
	bool "Inline instrumentation"
	help
	  Compiler directly inserts code checking shadow memory before
	  memory accesses. This is faster than outline (in some workloads
	  it gives about x2 boost over outline instrumentation), but
	  make kernel's .text size much bigger.
	  This requires a gcc version of 5.0 or later.

endchoice

config KASAN_S390_4_LEVEL_PAGING
	bool "KASan: use 4-level paging"
	depends on KASAN && S390
	help
	  Compiling the kernel with KASan disables automatic 3-level vs
	  4-level paging selection. 3-level paging is used by default (up
	  to 3TB of RAM with KASan enabled). This options allows to force
	  4-level paging instead.

config TEST_KASAN
	tristate "Module for testing kasan for bug detection"
	depends on m && KASAN
	help
	  This is a test module doing various nasty things like
	  out of bounds accesses, use after free. It is useful for testing
	  kernel debugging features like kernel address sanitizer.

endif