menu "Kernel hacking"

source "lib/Kconfig.debug"

config FRAME_POINTER
	bool
	default y

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 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 EARLY_PRINTK
	bool "Early printk support"
	default y
	help
	  Say Y here if you want to have an early console using the
	  earlyprintk=<name>[,<addr>][,<options>] kernel parameter. It
	  is assumed that the early console device has been initialised
	  by the boot loader prior to starting the Linux kernel.

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 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 FORCE_PAGES
        bool "Force lowmem to be mapped with 4K pages"
        help
          There are some advanced debug features that can only be done when
          memory is mapped with pages instead of sections. Enable this option
          to always map lowmem pages with pages. This may have a performance
          cost due to increased TLB pressure.

          If unsure say N.

config FREE_PAGES_RDONLY
        bool "Set pages as read only while on the buddy list"
        select FORCE_PAGES
        select DEBUG_PAGEALLOC
        help
          Pages are always mapped in the kernel. This means that anyone
          can write to the page if they have the address. Enable this option
          to mark pages as read only to trigger a fault if any code attempts
          to write to a page on the buddy list. This may have a performance
          impact.

          If unsure, say N.

config KERNEL_TEXT_RDONLY
        bool "Set kernel text section pages as read only"
	depends on FREE_PAGES_RDONLY
        help
          The kernel text pages are always mapped in the kernel.
	  This means that anyone can write to the page if they have
	  the address. Enable this option to mark the kernel text pages
	  as read only to trigger a fault if any code attempts to write
	  to a page part of the kernel text section. This may have a
	  performance impact.

          If unsure, say N.
endmenu