# SPDX-License-Identifier: GPL-2.0-onlyconfig 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 DEBUG_SLAB	bool "Debug slab memory allocations"	depends on DEBUG_KERNEL && SLAB	help	  Say Y here to have the kernel do limited verification on memory	  allocation as well as poisoning memory on free to catch use of freed	  memory. This can make kmalloc/kfree-intensive workloads much slower. config SLUB_DEBUG	default y	bool "Enable SLUB debugging support" if EXPERT	depends on SLUB && SYSFS && !SLUB_TINY	select STACKDEPOT if STACKTRACE_SUPPORT	help	  SLUB has extensive debug support features. Disabling these can	  result in significant savings in code size. This also disables	  SLUB sysfs support. /sys/slab will not exist and there will be	  no support for cache validation etc. config SLUB_DEBUG_ON	bool "SLUB debugging on by default"	depends on SLUB && SLUB_DEBUG	select STACKDEPOT_ALWAYS_INIT if STACKTRACE_SUPPORT	default n	help	  Boot with debugging on by default. SLUB boots by default with	  the runtime debug capabilities switched off. Enabling this is	  equivalent to specifying the "slub_debug" parameter on boot.	  There is no support for more fine grained debug control like	  possible with slub_debug=xxx. SLUB debugging may be switched	  off in a kernel built with CONFIG_SLUB_DEBUG_ON by specifying	  "slub_debug=-". 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_TABLE_CHECK	bool "Check for invalid mappings in user page tables"	depends on ARCH_SUPPORTS_PAGE_TABLE_CHECK	select PAGE_EXTENSION	help	  Check that anonymous page is not being mapped twice with read write	  permissions. Check that anonymous and file pages are not being	  erroneously shared. Since the checking is performed at the time	  entries are added and removed to user page tables, leaking, corruption	  and double mapping problems are detected synchronously. 	  If unsure say "n". config PAGE_TABLE_CHECK_ENFORCED	bool "Enforce the page table checking by default"	depends on PAGE_TABLE_CHECK	help	  Always enable page table checking.  By default the page table checking	  is disabled, and can be optionally enabled via page_table_check=on	  kernel parameter. This config enforces that page table check is always	  enabled. 	  If unsure say "n". 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. 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.