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menu "Kernel hacking"
source "lib/Kconfig.debug"
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_4K_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
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.
source "drivers/hwtracing/coresight/Kconfig"
endmenu
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