In addition to the set_memory_xx() functions which allows to change
the memory attributes of not (yet) used memory regions, implement a
set_memory_attr() function to:
- set the final memory protection after init on currently used
kernel regions.
- enable/disable kernel memory regions in the scope of DEBUG_PAGEALLOC.
Unlike the set_memory_xx() which can act in three step as the regions
are unused, this function must modify 'on the fly' as the kernel is
executing from them. At the moment only PPC32 will use it and changing
page attributes on the fly is not an issue.
Reported-by: kbuild test robot <lkp@intel.com>
[ruscur: cast "data" to unsigned long instead of int]
Signed-off-by: Christophe Leroy <christophe.leroy@csgroup.eu>
Signed-off-by: Russell Currey <ruscur@russell.cc>
Signed-off-by: Jordan Niethe <jniethe5@gmail.com>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
Link: https://lore.kernel.org/r/20210609013431.9805-9-jniethe5@gmail.com
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
