1f9ad21c3b
The set_memory_{ro/rw/nx/x}() functions are required for
STRICT_MODULE_RWX, and are generally useful primitives to have. This
implementation is designed to be generic across powerpc's many MMUs.
It's possible that this could be optimised to be faster for specific
MMUs.
This implementation does not handle cases where the caller is attempting
to change the mapping of the page it is executing from, or if another
CPU is concurrently using the page being altered. These cases likely
shouldn't happen, but a more complex implementation with MMU-specific code
could safely handle them.
On hash, the linear mapping is not kept in the linux pagetable, so this
will not change the protection if used on that range. Currently these
functions are not used on the linear map so just WARN for now.
apply_to_existing_page_range() does not work on huge pages so for now
disallow changing the protection of huge pages.
[jpn: - Allow set memory functions to be used without Strict RWX
- Hash: Disallow certain regions
- Have change_page_attr() take function pointers to manipulate ptes
- Radix: Add ptesync after set_pte_at()]
Signed-off-by: Russell Currey <ruscur@russell.cc>
Signed-off-by: Christophe Leroy <christophe.leroy@csgroup.eu>
Signed-off-by: Jordan Niethe <jniethe5@gmail.com>
Reviewed-by: Daniel Axtens <dja@axtens.net>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
Link: https://lore.kernel.org/r/20210609013431.9805-2-jniethe5@gmail.com
Linux kernel
============
There are several guides for kernel developers and users. These guides can
be rendered in a number of formats, like HTML and PDF. Please read
Documentation/admin-guide/README.rst first.
In order to build the documentation, use ``make htmldocs`` or
``make pdfdocs``. The formatted documentation can also be read online at:
https://www.kernel.org/doc/html/latest/
There are various text files in the Documentation/ subdirectory,
several of them using the Restructured Text markup notation.
Please read the Documentation/process/changes.rst file, as it contains the
requirements for building and running the kernel, and information about
the problems which may result by upgrading your kernel.