On Sat, Feb 18, 2023 at 01:14:05PM -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 unusual properties is that shadow stack memory is writable, but only in limited ways. These limits are applied via a specific PTE bit combination. Nevertheless, the memory is writable, and core mm code will need to apply the writable permissions in the typical paths that call pte_mkwrite(). In addition to VM_WRITE, the shadow stack VMA's will have a flag denoting that they are special shadow stack flavor of writable memory. So make pte_mkwrite() take a VMA, so that the x86 implementation of it can know to create regular writable memory or shadow stack memory. Apply the same changes for pmd_mkwrite() and huge_pte_mkwrite(). No functional change. Cc: linux-doc@xxxxxxxxxxxxxxx Cc: linux-kernel@xxxxxxxxxxxxxxx Cc: linux-alpha@xxxxxxxxxxxxxxx Cc: linux-snps-arc@xxxxxxxxxxxxxxxxxxx Cc: linux-arm-kernel@xxxxxxxxxxxxxxxxxxx Cc: linux-csky@xxxxxxxxxxxxxxx Cc: linux-hexagon@xxxxxxxxxxxxxxx Cc: linux-ia64@xxxxxxxxxxxxxxx Cc: loongarch@xxxxxxxxxxxxxxx Cc: linux-m68k@xxxxxxxxxxxxxxxxxxxx Cc: Michal Simek <monstr@xxxxxxxxx> Cc: Dinh Nguyen <dinguyen@xxxxxxxxxx> Cc: linux-mips@xxxxxxxxxxxxxxx Cc: openrisc@xxxxxxxxxxxxxxxxxxxx Cc: linux-parisc@xxxxxxxxxxxxxxx Cc: linuxppc-dev@xxxxxxxxxxxxxxxx Cc: linux-riscv@xxxxxxxxxxxxxxxxxxx Cc: linux-s390@xxxxxxxxxxxxxxx Cc: linux-sh@xxxxxxxxxxxxxxx Cc: sparclinux@xxxxxxxxxxxxxxx Cc: linux-um@xxxxxxxxxxxxxxxxxxx Cc: xen-devel@xxxxxxxxxxxxxxxxxxxx Cc: linux-arch@xxxxxxxxxxxxxxx Cc: linux-mm@xxxxxxxxx Tested-by: Pengfei Xu <pengfei.xu@xxxxxxxxx> Suggested-by: David Hildenbrand <david@xxxxxxxxxx> Signed-off-by: Rick Edgecombe <rick.p.edgecombe@xxxxxxxxx>
Acked-by: Deepak Gupta <debug@xxxxxxxxxxxx>
