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# SPDX-License-Identifier: GPL-2.0-only
config PAGE_EXTENSION
	bool "Extend memmap on extra space for more information on page"
	help
	  Extend memmap on extra space for more information on page. This
	  could be used for debugging features that need to insert extra
	  field for every page. This extension enables us to save memory
	  by not allocating this extra memory according to boottime
	  configuration.

config DEBUG_PAGEALLOC
	bool "Debug page memory allocations"
	depends on DEBUG_KERNEL
	depends on !HIBERNATION || ARCH_SUPPORTS_DEBUG_PAGEALLOC && !PPC && !SPARC
	select PAGE_POISONING if !ARCH_SUPPORTS_DEBUG_PAGEALLOC
	help
	  Unmap pages from the kernel linear mapping after free_pages().
	  Depending on runtime enablement, this results in a small or large
	  slowdown, but helps to find certain types of memory corruption.

	  Also, the state of page tracking structures is checked more often as
	  pages are being allocated and freed, as unexpected state changes
	  often happen for same reasons as memory corruption (e.g. double free,
	  use-after-free). The error reports for these checks can be augmented
	  with stack traces of last allocation and freeing of the page, when
	  PAGE_OWNER is also selected and enabled on boot.

	  For architectures which don't enable ARCH_SUPPORTS_DEBUG_PAGEALLOC,
	  fill the pages with poison patterns after free_pages() and verify
	  the patterns before alloc_pages(). Additionally, this option cannot
	  be enabled in combination with hibernation as that would result in
	  incorrect warnings of memory corruption after a resume because free
	  pages are not saved to the suspend image.

	  By default this option will have a small overhead, e.g. by not
	  allowing the kernel mapping to be backed by large pages on some
	  architectures. Even bigger overhead comes when the debugging is
	  enabled by DEBUG_PAGEALLOC_ENABLE_DEFAULT or the debug_pagealloc
	  command line parameter.

config DEBUG_PAGEALLOC_ENABLE_DEFAULT
	bool "Enable debug page memory allocations by default?"
	depends on DEBUG_PAGEALLOC
	help
	  Enable debug page memory allocations by default? This value
	  can be overridden by debug_pagealloc=off|on.

config PAGE_POISONING
	bool "Poison pages after freeing"
	help
	  Fill the pages with poison patterns after free_pages() and verify
	  the patterns before alloc_pages. The filling of the memory helps
	  reduce the risk of information leaks from freed data. This does
	  have a potential performance impact if enabled with the
	  "page_poison=1" kernel boot option.

	  Note that "poison" here is not the same thing as the "HWPoison"
	  for CONFIG_MEMORY_FAILURE. This is software poisoning only.

	  If you are only interested in sanitization of freed pages without
	  checking the poison pattern on alloc, you can boot the kernel with
	  "init_on_free=1" instead of enabling this.

	  If unsure, say N

config DEBUG_PAGE_REF
	bool "Enable tracepoint to track down page reference manipulation"
	depends on DEBUG_KERNEL
	depends on TRACEPOINTS
	help
	  This is a feature to add tracepoint for tracking down page reference
	  manipulation. This tracking is useful to diagnose functional failure
	  due to migration failures caused by page reference mismatches.  Be
	  careful when enabling this feature because it adds about 30 KB to the
	  kernel code.  However the runtime performance overhead is virtually
	  nil until the tracepoints are actually enabled.

config DEBUG_RODATA_TEST
    bool "Testcase for the marking rodata read-only"
    depends on STRICT_KERNEL_RWX
	help
      This option enables a testcase for the setting rodata read-only.