[PATCH v6 11/41] mm: Introduce pte_mkwrite_kernel()

[Deepak Gupta]

On Sat, Feb 18, 2023 at 01:14:03PM -0800, Rick Edgecombe wrote:
>The x86 Control-flow Enforcement Technology (CET) feature includes a new
>type of memory called shadow stack. This shadow stack memory has some
>unusual properties, which requires some core mm changes to function
>properly.
>
>One of these changes is to allow for pte_mkwrite() to create different
>types of writable memory (the existing conventionally writable type and
>also the new shadow stack type). Future patches will convert pte_mkwrite()
>to take a VMA in order to facilitate this, however there are places in the
>kernel where pte_mkwrite() is called outside of the context of a VMA.
>These are for kernel memory. So create a new variant called
>pte_mkwrite_kernel() and switch the kernel users over to it. Have
>pte_mkwrite() and pte_mkwrite_kernel() be the same for now. Future patches
>will introduce changes to make pte_mkwrite() take a VMA.
>
>Only do this for architectures that need it because they call pte_mkwrite()
>in arch code without an associated VMA. Since it will only currently be
>used in arch code, so do not include it in arch_pgtable_helpers.rst.
>
>Cc: linux-doc at vger.kernel.org
>Cc: linux-arm-kernel at lists.infradead.org
>Cc: linux-s390 at vger.kernel.org
>Cc: xen-devel at lists.xenproject.org
>Cc: linux-arch at vger.kernel.org
>Cc: linux-mm at kvack.org
>Tested-by: Pengfei Xu <pengfei.xu at intel.com>
>Suggested-by: David Hildenbrand <david at redhat.com>
>Signed-off-by: Rick Edgecombe <rick.p.edgecombe at intel.com>
>

Acked-by: Deepak Gupta <debug at rivosinc.com>