279 lines
9.9 KiB
Plaintext
279 lines
9.9 KiB
Plaintext
# SPDX-License-Identifier: GPL-2.0-only
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config PAGE_EXTENSION
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bool "Extend memmap on extra space for more information on page"
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help
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Extend memmap on extra space for more information on page. This
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could be used for debugging features that need to insert extra
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field for every page. This extension enables us to save memory
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by not allocating this extra memory according to boottime
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configuration.
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config DEBUG_PAGEALLOC
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bool "Debug page memory allocations"
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depends on DEBUG_KERNEL
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depends on !HIBERNATION || ARCH_SUPPORTS_DEBUG_PAGEALLOC && !PPC && !SPARC
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select PAGE_POISONING if !ARCH_SUPPORTS_DEBUG_PAGEALLOC
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help
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Unmap pages from the kernel linear mapping after free_pages().
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Depending on runtime enablement, this results in a small or large
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slowdown, but helps to find certain types of memory corruption.
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Also, the state of page tracking structures is checked more often as
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pages are being allocated and freed, as unexpected state changes
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often happen for same reasons as memory corruption (e.g. double free,
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use-after-free). The error reports for these checks can be augmented
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with stack traces of last allocation and freeing of the page, when
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PAGE_OWNER is also selected and enabled on boot.
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For architectures which don't enable ARCH_SUPPORTS_DEBUG_PAGEALLOC,
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fill the pages with poison patterns after free_pages() and verify
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the patterns before alloc_pages(). Additionally, this option cannot
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be enabled in combination with hibernation as that would result in
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incorrect warnings of memory corruption after a resume because free
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pages are not saved to the suspend image.
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By default this option will have a small overhead, e.g. by not
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allowing the kernel mapping to be backed by large pages on some
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architectures. Even bigger overhead comes when the debugging is
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enabled by DEBUG_PAGEALLOC_ENABLE_DEFAULT or the debug_pagealloc
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command line parameter.
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config DEBUG_PAGEALLOC_ENABLE_DEFAULT
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bool "Enable debug page memory allocations by default?"
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depends on DEBUG_PAGEALLOC
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help
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Enable debug page memory allocations by default? This value
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can be overridden by debug_pagealloc=off|on.
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config SLUB_DEBUG
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default y
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bool "Enable SLUB debugging support" if EXPERT
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depends on SYSFS && !SLUB_TINY
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select STACKDEPOT if STACKTRACE_SUPPORT
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help
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SLUB has extensive debug support features. Disabling these can
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result in significant savings in code size. While /sys/kernel/slab
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will still exist (with SYSFS enabled), it will not provide e.g. cache
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validation.
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config SLUB_DEBUG_ON
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bool "SLUB debugging on by default"
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depends on SLUB_DEBUG
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select STACKDEPOT_ALWAYS_INIT if STACKTRACE_SUPPORT
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default n
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help
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Boot with debugging on by default. SLUB boots by default with
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the runtime debug capabilities switched off. Enabling this is
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equivalent to specifying the "slab_debug" parameter on boot.
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There is no support for more fine grained debug control like
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possible with slab_debug=xxx. SLUB debugging may be switched
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off in a kernel built with CONFIG_SLUB_DEBUG_ON by specifying
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"slab_debug=-".
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config PAGE_OWNER
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bool "Track page owner"
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depends on DEBUG_KERNEL && STACKTRACE_SUPPORT
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select DEBUG_FS
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select STACKTRACE
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select STACKDEPOT
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select PAGE_EXTENSION
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help
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This keeps track of what call chain is the owner of a page, may
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help to find bare alloc_page(s) leaks. Even if you include this
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feature on your build, it is disabled in default. You should pass
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"page_owner=on" to boot parameter in order to enable it. Eats
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a fair amount of memory if enabled. See tools/mm/page_owner_sort.c
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for user-space helper.
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If unsure, say N.
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config PAGE_TABLE_CHECK
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bool "Check for invalid mappings in user page tables"
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depends on ARCH_SUPPORTS_PAGE_TABLE_CHECK
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depends on EXCLUSIVE_SYSTEM_RAM
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select PAGE_EXTENSION
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help
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Check that anonymous page is not being mapped twice with read write
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permissions. Check that anonymous and file pages are not being
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erroneously shared. Since the checking is performed at the time
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entries are added and removed to user page tables, leaking, corruption
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and double mapping problems are detected synchronously.
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If unsure say "n".
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config PAGE_TABLE_CHECK_ENFORCED
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bool "Enforce the page table checking by default"
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depends on PAGE_TABLE_CHECK
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help
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Always enable page table checking. By default the page table checking
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is disabled, and can be optionally enabled via page_table_check=on
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kernel parameter. This config enforces that page table check is always
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enabled.
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If unsure say "n".
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config PAGE_POISONING
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bool "Poison pages after freeing"
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help
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Fill the pages with poison patterns after free_pages() and verify
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the patterns before alloc_pages. The filling of the memory helps
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reduce the risk of information leaks from freed data. This does
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have a potential performance impact if enabled with the
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"page_poison=1" kernel boot option.
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Note that "poison" here is not the same thing as the "HWPoison"
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for CONFIG_MEMORY_FAILURE. This is software poisoning only.
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If you are only interested in sanitization of freed pages without
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checking the poison pattern on alloc, you can boot the kernel with
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"init_on_free=1" instead of enabling this.
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If unsure, say N
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config DEBUG_PAGE_REF
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bool "Enable tracepoint to track down page reference manipulation"
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depends on DEBUG_KERNEL
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depends on TRACEPOINTS
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help
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This is a feature to add tracepoint for tracking down page reference
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manipulation. This tracking is useful to diagnose functional failure
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due to migration failures caused by page reference mismatches. Be
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careful when enabling this feature because it adds about 30 KB to the
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kernel code. However the runtime performance overhead is virtually
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nil until the tracepoints are actually enabled.
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config DEBUG_RODATA_TEST
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bool "Testcase for the marking rodata read-only"
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depends on STRICT_KERNEL_RWX
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help
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This option enables a testcase for the setting rodata read-only.
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config ARCH_HAS_DEBUG_WX
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bool
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config DEBUG_WX
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bool "Warn on W+X mappings at boot"
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depends on ARCH_HAS_DEBUG_WX
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depends on MMU
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select PTDUMP_CORE
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help
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Generate a warning if any W+X mappings are found at boot.
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This is useful for discovering cases where the kernel is leaving W+X
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mappings after applying NX, as such mappings are a security risk.
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Look for a message in dmesg output like this:
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<arch>/mm: Checked W+X mappings: passed, no W+X pages found.
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or like this, if the check failed:
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<arch>/mm: Checked W+X mappings: failed, <N> W+X pages found.
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Note that even if the check fails, your kernel is possibly
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still fine, as W+X mappings are not a security hole in
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themselves, what they do is that they make the exploitation
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of other unfixed kernel bugs easier.
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There is no runtime or memory usage effect of this option
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once the kernel has booted up - it's a one time check.
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If in doubt, say "Y".
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config GENERIC_PTDUMP
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bool
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config PTDUMP_CORE
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bool
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config PTDUMP_DEBUGFS
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bool "Export kernel pagetable layout to userspace via debugfs"
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depends on DEBUG_KERNEL
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depends on DEBUG_FS
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depends on GENERIC_PTDUMP
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select PTDUMP_CORE
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help
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Say Y here if you want to show the kernel pagetable layout in a
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debugfs file. This information is only useful for kernel developers
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who are working in architecture specific areas of the kernel.
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It is probably not a good idea to enable this feature in a production
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kernel.
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If in doubt, say N.
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config HAVE_DEBUG_KMEMLEAK
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bool
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config DEBUG_KMEMLEAK
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bool "Kernel memory leak detector"
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depends on DEBUG_KERNEL && HAVE_DEBUG_KMEMLEAK
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select DEBUG_FS
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select STACKTRACE if STACKTRACE_SUPPORT
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select KALLSYMS
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select CRC32
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select STACKDEPOT
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select STACKDEPOT_ALWAYS_INIT if !DEBUG_KMEMLEAK_DEFAULT_OFF
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help
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Say Y here if you want to enable the memory leak
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detector. The memory allocation/freeing is traced in a way
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similar to the Boehm's conservative garbage collector, the
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difference being that the orphan objects are not freed but
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only shown in /sys/kernel/debug/kmemleak. Enabling this
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feature will introduce an overhead to memory
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allocations. See Documentation/dev-tools/kmemleak.rst for more
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details.
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Enabling SLUB_DEBUG may increase the chances of finding leaks
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due to the slab objects poisoning.
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In order to access the kmemleak file, debugfs needs to be
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mounted (usually at /sys/kernel/debug).
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config DEBUG_KMEMLEAK_MEM_POOL_SIZE
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int "Kmemleak memory pool size"
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depends on DEBUG_KMEMLEAK
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range 200 1000000
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default 16000
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help
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Kmemleak must track all the memory allocations to avoid
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reporting false positives. Since memory may be allocated or
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freed before kmemleak is fully initialised, use a static pool
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of metadata objects to track such callbacks. After kmemleak is
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fully initialised, this memory pool acts as an emergency one
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if slab allocations fail.
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config DEBUG_KMEMLEAK_DEFAULT_OFF
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bool "Default kmemleak to off"
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depends on DEBUG_KMEMLEAK
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help
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Say Y here to disable kmemleak by default. It can then be enabled
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on the command line via kmemleak=on.
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config DEBUG_KMEMLEAK_AUTO_SCAN
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bool "Enable kmemleak auto scan thread on boot up"
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default y
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depends on DEBUG_KMEMLEAK
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help
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Depending on the cpu, kmemleak scan may be cpu intensive and can
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stall user tasks at times. This option enables/disables automatic
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kmemleak scan at boot up.
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Say N here to disable kmemleak auto scan thread to stop automatic
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scanning. Disabling this option disables automatic reporting of
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memory leaks.
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If unsure, say Y.
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config PER_VMA_LOCK_STATS
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bool "Statistics for per-vma locks"
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depends on PER_VMA_LOCK
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help
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Say Y here to enable success, retry and failure counters of page
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faults handled under protection of per-vma locks. When enabled, the
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counters are exposed in /proc/vmstat. This information is useful for
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kernel developers to evaluate effectiveness of per-vma locks and to
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identify pathological cases. Counting these events introduces a small
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overhead in the page fault path.
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If in doubt, say N.
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