[mirror_ubuntu-bionic-kernel.git] / arch / arm64 / Kconfig.debug

menu "Kernel hacking"

source "lib/Kconfig.debug"

config ARM64_PTDUMP_CORE
	def_bool n

config ARM64_PTDUMP_DEBUGFS
	bool "Export kernel pagetable layout to userspace via debugfs"
	depends on DEBUG_KERNEL
	select ARM64_PTDUMP_CORE
	select DEBUG_FS
        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.

config PID_IN_CONTEXTIDR
	bool "Write the current PID to the CONTEXTIDR register"
	help
	  Enabling this option causes the kernel to write the current PID to
	  the CONTEXTIDR register, at the expense of some additional
	  instructions during context switch. Say Y here only if you are
	  planning to use hardware trace tools with this kernel.

config ARM64_RANDOMIZE_TEXT_OFFSET
	bool "Randomize TEXT_OFFSET at build time"
	help
	  Say Y here if you want the image load offset (AKA TEXT_OFFSET)
	  of the kernel to be randomized at build-time. When selected,
	  this option will cause TEXT_OFFSET to be randomized upon any
	  build of the kernel, and the offset will be reflected in the
	  text_offset field of the resulting Image. This can be used to
	  fuzz-test bootloaders which respect text_offset.

	  This option is intended for bootloader and/or kernel testing
	  only. Bootloaders must make no assumptions regarding the value
	  of TEXT_OFFSET and platforms must not require a specific
	  value.

config DEBUG_WX
	bool "Warn on W+X mappings at boot"
	select ARM64_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.
	  This check also includes UXN, which should be set on all kernel
	  mappings.

	  Look for a message in dmesg output like this:

	    arm64/mm: Checked W+X mappings: passed, no W+X pages found.

	  or like this, if the check failed:

	    arm64/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 DEBUG_ALIGN_RODATA
	depends on STRICT_KERNEL_RWX
	bool "Align linker sections up to SECTION_SIZE"
	help
	  If this option is enabled, sections that may potentially be marked as
	  read only or non-executable will be aligned up to the section size of
	  the kernel. This prevents sections from being split into pages and
	  avoids a potential TLB penalty. The downside is an increase in
	  alignment and potentially wasted space. Turn on this option if
	  performance is more important than memory pressure.

	  If in doubt, say N.

config DEBUG_EFI
	depends on EFI && DEBUG_INFO
	bool "UEFI debugging"
	help
	  Enable this option to include EFI specific debugging features into
	  the kernel that are only useful when using a debug build of the
	  UEFI firmware

config ARM64_RELOC_TEST
	depends on m
	tristate "Relocation testing module"

source "drivers/hwtracing/coresight/Kconfig"

endmenu
Commit	Line	Data
8c2c3df3 CM	1	menu "Kernel hacking"
	2
	3	source "lib/Kconfig.debug"
	4
4ddb9bf8 LA	5	config ARM64_PTDUMP_CORE
	6	def_bool n
	7
	8	config ARM64_PTDUMP_DEBUGFS
c9465b4e LA	9	bool "Export kernel pagetable layout to userspace via debugfs"
c9465b4e LA	10	depends on DEBUG_KERNEL
4ddb9bf8	11	select ARM64_PTDUMP_CORE
c9465b4e LA	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.
604c8e67 MR	19
604c8e67 MR	20	If in doubt, say N.
c9465b4e	21
ec45d1cf WD	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
da57a369 MR	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
1404d6f1 LA	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
da141706	74	config DEBUG_ALIGN_RODATA
0f5bf6d0	75	depends on STRICT_KERNEL_RWX
da141706 LA	76	bool "Align linker sections up to SECTION_SIZE"
	77	help
	78	If this option is enabled, sections that may potentially be marked as
	79	read only or non-executable will be aligned up to the section size of
	80	the kernel. This prevents sections from being split into pages and
	81	avoids a potential TLB penalty. The downside is an increase in
	82	alignment and potentially wasted space. Turn on this option if
	83	performance is more important than memory pressure.
	84
604c8e67	85	If in doubt, say N.
da141706	86
757b435a AB	87	config DEBUG_EFI
	88	depends on EFI && DEBUG_INFO
	89	bool "UEFI debugging"
	90	help
	91	Enable this option to include EFI specific debugging features into
	92	the kernel that are only useful when using a debug build of the
	93	UEFI firmware
	94
214fad55 AB	95	config ARM64_RELOC_TEST
	96	depends on m
	97	tristate "Relocation testing module"
	98
01081f5a	99	source "drivers/hwtracing/coresight/Kconfig"
3288731e	100
8c2c3df3	101	endmenu