On Wed, Oct 7, 2015 at 1:24 PM, Dave Hansen <dave@xxxxxxxx> wrote: > On 10/03/2015 01:17 AM, Ingo Molnar wrote: >> Right now the native x86 PTE format allows two protection related bits for >> user-space pages: >> >> _PAGE_BIT_RW: if 0 the page is read-only, if 1 then it's read-write >> _PAGE_BIT_NX: if 0 the page is executable, if 1 then it's not executable >> >> As discussed previously, pkeys allows 'true execute only (--x)' mappings. >> >> Another possibility would be 'true write-only (-w-)' mappings. > > How would those work? > > Protection Keys has a Write-Disable and an Access-Disable bit. But, > Access-Disable denies _all_ data access to the region. There's no way > to allow only writes. Weird. I wonder why Intel did that. I also wonder whether EPT can do write-only. --Andy -- To unsubscribe, send a message with 'unsubscribe linux-mm' in the body to majordomo@xxxxxxxxx. For more info on Linux MM, see: http://www.linux-mm.org/ . Don't email: <a href=mailto:"dont@xxxxxxxxx";> email@xxxxxxxxx </a>