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

menu "Kernel hacking"

source "lib/Kconfig.debug"

config FRAME_POINTER
	bool
	default y

config ARM64_PTDUMP
	bool "Export kernel pagetable layout to userspace via debugfs"
	depends on DEBUG_KERNEL
	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 STRICT_DEVMEM
	bool "Filter access to /dev/mem"
	depends on MMU
	help
	  If this option is disabled, you allow userspace (root) access to all
	  of memory, including kernel and userspace memory. Accidental
	  access to this is obviously disastrous, but specific access can
	  be used by people debugging the kernel.

	  If this option is switched on, the /dev/mem file only allows
	  userspace access to memory mapped peripherals.

	  If in doubt, say Y.

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_SET_MODULE_RONX
        bool "Set loadable kernel module data as NX and text as RO"
        depends on MODULES
        help
          This option helps catch unintended modifications to loadable
          kernel module's text and read-only data. It also prevents execution
          of module data. Such protection may interfere with run-time code
          patching and dynamic kernel tracing - and they might also protect
          against certain classes of kernel exploits.
          If in doubt, say "N".

config DEBUG_RODATA
	bool "Make kernel text and rodata read-only"
	help
	  If this is set, kernel text and rodata will be made read-only. This
	  is to help catch accidental or malicious attempts to change the
	  kernel's executable code. Additionally splits rodata from kernel
	  text so it can be made explicitly non-executable.

          If in doubt, say Y

config DEBUG_ALIGN_RODATA
	depends on DEBUG_RODATA && !ARM64_64K_PAGES
	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

source "drivers/hwtracing/coresight/Kconfig"

endmenu
Commit	Line	Data
8c2c3df3 CM	1	menu "Kernel hacking"
	2
	3	source "lib/Kconfig.debug"
	4
	5	config FRAME_POINTER
	6	bool
	7	default y
	8
c9465b4e LA	9	config ARM64_PTDUMP
	10	bool "Export kernel pagetable layout to userspace via debugfs"
	11	depends on DEBUG_KERNEL
	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	If in doubt, say "N"
	20
d253b440 LA	21	config STRICT_DEVMEM
	22	bool "Filter access to /dev/mem"
	23	depends on MMU
	24	help
	25	If this option is disabled, you allow userspace (root) access to all
	26	of memory, including kernel and userspace memory. Accidental
	27	access to this is obviously disastrous, but specific access can
	28	be used by people debugging the kernel.
	29
	30	If this option is switched on, the /dev/mem file only allows
	31	userspace access to memory mapped peripherals.
	32
	33	If in doubt, say Y.
	34
ec45d1cf WD	35	config PID_IN_CONTEXTIDR
	36	bool "Write the current PID to the CONTEXTIDR register"
	37	help
	38	Enabling this option causes the kernel to write the current PID to
	39	the CONTEXTIDR register, at the expense of some additional
	40	instructions during context switch. Say Y here only if you are
	41	planning to use hardware trace tools with this kernel.
	42
da57a369 MR	43	config ARM64_RANDOMIZE_TEXT_OFFSET
	44	bool "Randomize TEXT_OFFSET at build time"
	45	help
	46	Say Y here if you want the image load offset (AKA TEXT_OFFSET)
	47	of the kernel to be randomized at build-time. When selected,
	48	this option will cause TEXT_OFFSET to be randomized upon any
	49	build of the kernel, and the offset will be reflected in the
	50	text_offset field of the resulting Image. This can be used to
	51	fuzz-test bootloaders which respect text_offset.
	52
	53	This option is intended for bootloader and/or kernel testing
	54	only. Bootloaders must make no assumptions regarding the value
	55	of TEXT_OFFSET and platforms must not require a specific
	56	value.
	57
11d91a77 LA	58	config DEBUG_SET_MODULE_RONX
	59	bool "Set loadable kernel module data as NX and text as RO"
	60	depends on MODULES
	61	help
	62	This option helps catch unintended modifications to loadable
	63	kernel module's text and read-only data. It also prevents execution
	64	of module data. Such protection may interfere with run-time code
	65	patching and dynamic kernel tracing - and they might also protect
	66	against certain classes of kernel exploits.
	67	If in doubt, say "N".
	68
da141706 LA	69	config DEBUG_RODATA
	70	bool "Make kernel text and rodata read-only"
	71	help
	72	If this is set, kernel text and rodata will be made read-only. This
	73	is to help catch accidental or malicious attempts to change the
	74	kernel's executable code. Additionally splits rodata from kernel
	75	text so it can be made explicitly non-executable.
	76
	77	If in doubt, say Y
	78
	79	config DEBUG_ALIGN_RODATA
	80	depends on DEBUG_RODATA && !ARM64_64K_PAGES
	81	bool "Align linker sections up to SECTION_SIZE"
	82	help
	83	If this option is enabled, sections that may potentially be marked as
	84	read only or non-executable will be aligned up to the section size of
	85	the kernel. This prevents sections from being split into pages and
	86	avoids a potential TLB penalty. The downside is an increase in
	87	alignment and potentially wasted space. Turn on this option if
	88	performance is more important than memory pressure.
	89
	90	If in doubt, say N
	91
01081f5a	92	source "drivers/hwtracing/coresight/Kconfig"
3288731e	93
8c2c3df3	94	endmenu