From: Dave Hansen > Sent: 09 February 2022 22:52 > > On 1/30/22 13:18, Rick Edgecombe wrote: > > Like a writable data page, a shadow stack page is writable, and becomes > > read-only during copy-on-write, but it is always dirty. > > One other thing... > > The language in these changelogs is a bit sloppy. For instance, what > does "always dirty" mean here? pte_dirty()? Or strictly _PAGE_DIRTY? > > In other words, logically dirty, or literally "has *the* dirty bit set"? Doesn't COW have to set it readonly - so that the access faults. And then set the fault code set it readonly+dirty (without write) to allow the shadow stack accesses to not-fault. Or am I mis-guessing what the docs actually say? David - Registered Address Lakeside, Bramley Road, Mount Farm, Milton Keynes, MK1 1PT, UK Registration No: 1397386 (Wales)
