Re: [PATCH v23 09/28] x86/mm: Introduce _PAGE_COW

2021-03-22 Thread Kirill A. Shutemov
On Tue, Mar 16, 2021 at 08:10:35AM -0700, Yu-cheng Yu wrote: > There is essentially no room left in the x86 hardware PTEs on some OSes > (not Linux). That left the hardware architects looking for a way to > represent a new memory type (shadow stack) within the existing bits. > They chose to

[PATCH v23 09/28] x86/mm: Introduce _PAGE_COW

2021-03-16 Thread Yu-cheng Yu
There is essentially no room left in the x86 hardware PTEs on some OSes (not Linux). That left the hardware architects looking for a way to represent a new memory type (shadow stack) within the existing bits. They chose to repurpose a lightly-used state: Write=0, Dirty=1. The reason it's lightly