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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_OWNER
+ bool "Track page owner"
+ depends on DEBUG_KERNEL && STACKTRACE_SUPPORT
+ select DEBUG_FS
+ select STACKTRACE
+ select STACKDEPOT
+ select PAGE_EXTENSION
+ help
+ This keeps track of what call chain is the owner of a page, may
+ help to find bare alloc_page(s) leaks. Even if you include this
+ feature on your build, it is disabled in default. You should pass
+ "page_owner=on" to boot parameter in order to enable it. Eats
+ a fair amount of memory if enabled. See tools/vm/page_owner_sort.c
+ for user-space helper.
+
+ If unsure, say N.
+
+config PAGE_POISONING
+ bool "Poison pages after freeing"
+ select PAGE_POISONING_NO_SANITY if HIBERNATION
+ 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 unsure, say N
+
+config PAGE_POISONING_NO_SANITY
+ depends on PAGE_POISONING
+ bool "Only poison, don't sanity check"
+ help
+ Skip the sanity checking on alloc, only fill the pages with
+ poison on free. This reduces some of the overhead of the
+ poisoning feature.
+
+ If you are only interested in sanitization, say Y. Otherwise
+ say N.
+
+config PAGE_POISONING_ZERO
+ bool "Use zero for poisoning instead of debugging value"
+ depends on PAGE_POISONING
+ help
+ Instead of using the existing poison value, fill the pages with
+ zeros. This makes it harder to detect when errors are occurring
+ due to sanitization but the zeroing at free means that it is
+ no longer necessary to write zeros when GFP_ZERO is used on
+ allocation.
+
+ 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.
+
+config ARCH_HAS_DEBUG_WX
+ bool
+
+config DEBUG_WX
+ bool "Warn on W+X mappings at boot"
+ depends on ARCH_HAS_DEBUG_WX
+ depends on MMU
+ select PTDUMP_CORE
+ help
+ Generate a warning if any W+X mappings are found at boot.
+
+ This is useful for discovering cases where the kernel is leaving W+X
+ mappings after applying NX, as such mappings are a security risk.
+
+ Look for a message in dmesg output like this:
+
+ <arch>/mm: Checked W+X mappings: passed, no W+X pages found.
+
+ or like this, if the check failed:
+
+ <arch>/mm: Checked W+X mappings: failed, <N> W+X pages found.
+
+ Note that even if the check fails, your kernel is possibly
+ still fine, as W+X mappings are not a security hole in
+ themselves, what they do is that they make the exploitation
+ of other unfixed kernel bugs easier.
+
+ There is no runtime or memory usage effect of this option
+ once the kernel has booted up - it's a one time check.
+
+ If in doubt, say "Y".
+
+config GENERIC_PTDUMP
+ bool
+
+config PTDUMP_CORE
+ bool
+
+config PTDUMP_DEBUGFS
+ bool "Export kernel pagetable layout to userspace via debugfs"
+ depends on DEBUG_KERNEL
+ depends on DEBUG_FS
+ depends on GENERIC_PTDUMP
+ select PTDUMP_CORE
+ help
+ Say Y here if you want to show the kernel pagetable layout in a
+ debugfs file. This information is only useful for kernel developers
+ who are working in architecture specific areas of the kernel.
+ It is probably not a good idea to enable this feature in a production
+ kernel.
+
+ If in doubt, say N.