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Linux/arch/arm64/Kconfig.debug

  1 menu "Kernel hacking"
  2 
  3 source "lib/Kconfig.debug"
  4 
  5 config ARM64_PTDUMP_CORE
  6         def_bool n
  7 
  8 config ARM64_PTDUMP_DEBUGFS
  9         bool "Export kernel pagetable layout to userspace via debugfs"
 10         depends on DEBUG_KERNEL
 11         select ARM64_PTDUMP_CORE
 12         select DEBUG_FS
 13         help
 14           Say Y here if you want to show the kernel pagetable layout in a
 15           debugfs file. This information is only useful for kernel developers
 16           who are working in architecture specific areas of the kernel.
 17           It is probably not a good idea to enable this feature in a production
 18           kernel.
 19 
 20           If in doubt, say N.
 21 
 22 config PID_IN_CONTEXTIDR
 23         bool "Write the current PID to the CONTEXTIDR register"
 24         help
 25           Enabling this option causes the kernel to write the current PID to
 26           the CONTEXTIDR register, at the expense of some additional
 27           instructions during context switch. Say Y here only if you are
 28           planning to use hardware trace tools with this kernel.
 29 
 30 config ARM64_RANDOMIZE_TEXT_OFFSET
 31         bool "Randomize TEXT_OFFSET at build time"
 32         help
 33           Say Y here if you want the image load offset (AKA TEXT_OFFSET)
 34           of the kernel to be randomized at build-time. When selected,
 35           this option will cause TEXT_OFFSET to be randomized upon any
 36           build of the kernel, and the offset will be reflected in the
 37           text_offset field of the resulting Image. This can be used to
 38           fuzz-test bootloaders which respect text_offset.
 39 
 40           This option is intended for bootloader and/or kernel testing
 41           only. Bootloaders must make no assumptions regarding the value
 42           of TEXT_OFFSET and platforms must not require a specific
 43           value.
 44 
 45 config DEBUG_WX
 46         bool "Warn on W+X mappings at boot"
 47         select ARM64_PTDUMP_CORE
 48         ---help---
 49           Generate a warning if any W+X mappings are found at boot.
 50 
 51           This is useful for discovering cases where the kernel is leaving
 52           W+X mappings after applying NX, as such mappings are a security risk.
 53           This check also includes UXN, which should be set on all kernel
 54           mappings.
 55 
 56           Look for a message in dmesg output like this:
 57 
 58             arm64/mm: Checked W+X mappings: passed, no W+X pages found.
 59 
 60           or like this, if the check failed:
 61 
 62             arm64/mm: Checked W+X mappings: FAILED, <N> W+X pages found.
 63 
 64           Note that even if the check fails, your kernel is possibly
 65           still fine, as W+X mappings are not a security hole in
 66           themselves, what they do is that they make the exploitation
 67           of other unfixed kernel bugs easier.
 68 
 69           There is no runtime or memory usage effect of this option
 70           once the kernel has booted up - it's a one time check.
 71 
 72           If in doubt, say "Y".
 73 
 74 config DEBUG_SET_MODULE_RONX
 75         bool "Set loadable kernel module data as NX and text as RO"
 76         depends on MODULES
 77         default y
 78         help
 79           Is this is set, kernel module text and rodata will be made read-only.
 80           This is to help catch accidental or malicious attempts to change the
 81           kernel's executable code.
 82 
 83           If in doubt, say Y.
 84 
 85 config DEBUG_ALIGN_RODATA
 86         depends on DEBUG_RODATA
 87         bool "Align linker sections up to SECTION_SIZE"
 88         help
 89           If this option is enabled, sections that may potentially be marked as
 90           read only or non-executable will be aligned up to the section size of
 91           the kernel. This prevents sections from being split into pages and
 92           avoids a potential TLB penalty. The downside is an increase in
 93           alignment and potentially wasted space. Turn on this option if
 94           performance is more important than memory pressure.
 95 
 96           If in doubt, say N.
 97 
 98 source "drivers/hwtracing/coresight/Kconfig"
 99 
100 endmenu

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