Re: [PATCH v8 17/40] mm: Move VM_UFFD_MINOR_BIT from 37 to 38

On 19.03.23 01:15, Rick Edgecombe wrote:

From: Yu-cheng Yu <redacted>

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.

Future patches will introduce a new VM flag VM_SHADOW_STACK that will be
VM_HIGH_ARCH_BIT_5. VM_HIGH_ARCH_BIT_1 through VM_HIGH_ARCH_BIT_4 are
bits 32-36, and bit 37 is the unrelated VM_UFFD_MINOR_BIT. For the sake
of order, make all VM_HIGH_ARCH_BITs stay together by moving
VM_UFFD_MINOR_BIT from 37 to 38. This will allow VM_SHADOW_STACK to be
introduced as 37.

Co-developed-by: Rick Edgecombe <rick.p.edgecombe@intel.com>
Signed-off-by: Yu-cheng Yu <redacted>
Signed-off-by: Rick Edgecombe <rick.p.edgecombe@intel.com>
Reviewed-by: Kees Cook <redacted>
Reviewed-by: Axel Rasmussen <axelrasmussen@google.com>
Acked-by: Mike Rapoport (IBM) <rppt@kernel.org>
Acked-by: Peter Xu <peterx@redhat.com>
Tested-by: Pengfei Xu <redacted>
Tested-by: John Allen <john.allen@amd.com>
Tested-by: Kees Cook <redacted>
---

Reviewed-by: David Hildenbrand <redacted>

-- 
Thanks,

David / dhildenb