mm/Kconfig.debug

   1 # SPDX-License-Identifier: GPL-2.0-only
   2 config PAGE_EXTENSION
   3         bool "Extend memmap on extra space for more information on page"
   4         ---help---
   5           Extend memmap on extra space for more information on page. This
   6           could be used for debugging features that need to insert extra
   7           field for every page. This extension enables us to save memory
   8           by not allocating this extra memory according to boottime
   9           configuration.
  10
  11 config DEBUG_PAGEALLOC
  12         bool "Debug page memory allocations"
  13         depends on DEBUG_KERNEL
  14         depends on !HIBERNATION || ARCH_SUPPORTS_DEBUG_PAGEALLOC && !PPC && !SPARC
  15         select PAGE_POISONING if !ARCH_SUPPORTS_DEBUG_PAGEALLOC
  16         ---help---
  17           Unmap pages from the kernel linear mapping after free_pages().
  18           Depending on runtime enablement, this results in a small or large
  19           slowdown, but helps to find certain types of memory corruption.
  20
  21           Also, the state of page tracking structures is checked more often as
  22           pages are being allocated and freed, as unexpected state changes
  23           often happen for same reasons as memory corruption (e.g. double free,
  24           use-after-free). The error reports for these checks can be augmented
  25           with stack traces of last allocation and freeing of the page, when
  26           PAGE_OWNER is also selected and enabled on boot.
  27
  28           For architectures which don't enable ARCH_SUPPORTS_DEBUG_PAGEALLOC,
  29           fill the pages with poison patterns after free_pages() and verify
  30           the patterns before alloc_pages(). Additionally, this option cannot
  31           be enabled in combination with hibernation as that would result in
  32           incorrect warnings of memory corruption after a resume because free
  33           pages are not saved to the suspend image.
  34
  35           By default this option will have a small overhead, e.g. by not
  36           allowing the kernel mapping to be backed by large pages on some
  37           architectures. Even bigger overhead comes when the debugging is
  38           enabled by DEBUG_PAGEALLOC_ENABLE_DEFAULT or the debug_pagealloc
  39           command line parameter.
  40
  41 config DEBUG_PAGEALLOC_ENABLE_DEFAULT
  42         bool "Enable debug page memory allocations by default?"
  43         depends on DEBUG_PAGEALLOC
  44         ---help---
  45           Enable debug page memory allocations by default? This value
  46           can be overridden by debug_pagealloc=off|on.
  47
  48 config PAGE_OWNER
  49         bool "Track page owner"
  50         depends on DEBUG_KERNEL && STACKTRACE_SUPPORT
  51         select DEBUG_FS
  52         select STACKTRACE
  53         select STACKDEPOT
  54         select PAGE_EXTENSION
  55         help
  56           This keeps track of what call chain is the owner of a page, may
  57           help to find bare alloc_page(s) leaks. Even if you include this
  58           feature on your build, it is disabled in default. You should pass
  59           "page_owner=on" to boot parameter in order to enable it. Eats
  60           a fair amount of memory if enabled. See tools/vm/page_owner_sort.c
  61           for user-space helper.
  62
  63           If unsure, say N.
  64
  65 config PAGE_POISONING
  66         bool "Poison pages after freeing"
  67         select PAGE_POISONING_NO_SANITY if HIBERNATION
  68         ---help---
  69           Fill the pages with poison patterns after free_pages() and verify
  70           the patterns before alloc_pages. The filling of the memory helps
  71           reduce the risk of information leaks from freed data. This does
  72           have a potential performance impact if enabled with the
  73           "page_poison=1" kernel boot option.
  74
  75           Note that "poison" here is not the same thing as the "HWPoison"
  76           for CONFIG_MEMORY_FAILURE. This is software poisoning only.
  77
  78           If unsure, say N
  79
  80 config PAGE_POISONING_NO_SANITY
  81         depends on PAGE_POISONING
  82         bool "Only poison, don't sanity check"
  83         ---help---
  84            Skip the sanity checking on alloc, only fill the pages with
  85            poison on free. This reduces some of the overhead of the
  86            poisoning feature.
  87
  88            If you are only interested in sanitization, say Y. Otherwise
  89            say N.
  90
  91 config PAGE_POISONING_ZERO
  92         bool "Use zero for poisoning instead of debugging value"
  93         depends on PAGE_POISONING
  94         ---help---
  95            Instead of using the existing poison value, fill the pages with
  96            zeros. This makes it harder to detect when errors are occurring
  97            due to sanitization but the zeroing at free means that it is
  98            no longer necessary to write zeros when GFP_ZERO is used on
  99            allocation.
 100
 101            If unsure, say N
 102
 103 config DEBUG_PAGE_REF
 104         bool "Enable tracepoint to track down page reference manipulation"
 105         depends on DEBUG_KERNEL
 106         depends on TRACEPOINTS
 107         ---help---
 108           This is a feature to add tracepoint for tracking down page reference
 109           manipulation. This tracking is useful to diagnose functional failure
 110           due to migration failures caused by page reference mismatches.  Be
 111           careful when enabling this feature because it adds about 30 KB to the
 112           kernel code.  However the runtime performance overhead is virtually
 113           nil until the tracepoints are actually enabled.
 114
 115 config DEBUG_RODATA_TEST
 116     bool "Testcase for the marking rodata read-only"
 117     depends on STRICT_KERNEL_RWX
 118     ---help---
 119       This option enables a testcase for the setting rodata read-only.
 120
 121 config GENERIC_PTDUMP
 122         bool
 123
 124 config PTDUMP_CORE
 125         bool
 126
 127 config PTDUMP_DEBUGFS
 128         bool "Export kernel pagetable layout to userspace via debugfs"
 129         depends on DEBUG_KERNEL
 130         depends on DEBUG_FS
 131         depends on GENERIC_PTDUMP
 132         select PTDUMP_CORE
 133         help
 134           Say Y here if you want to show the kernel pagetable layout in a
 135           debugfs file. This information is only useful for kernel developers
 136           who are working in architecture specific areas of the kernel.
 137           It is probably not a good idea to enable this feature in a production
 138           kernel.
 139
 140           If in doubt, say N.