On Tue, Aug 7, 2018 at 11:34 AM, Dave Hansen <dave.hansen@xxxxxxxxx> wrote: > On 08/07/2018 03:24 AM, Joerg Roedel wrote: >> The function sets the global-bit on cloned PMD entries, >> which only makes sense when the permissions are identical >> between the user and the kernel page-table. >> >> Further, only write-permissions are cleared for entry-text >> and kernel-text sections, which are not writeable anyway. > > I think this patch is correct, but I'd be curious if Andy remembers why > we chose to clear _PAGE_RW on these things. It might have been that we > were trying to say that the *entry* code shouldn't write to this stuff, > regardless of whether the normal kernel can. > > But, either way, I agree with the logic here that Global pages must > share permissions between both mappings, so feel free to add my Ack. I > just want to make sure Andy doesn't remember some detail I'm forgetting. I suspect it's because we used to (and maybe still do) initialize the user tables before mark_read_only().
