Messages in this thread | | | Date | Thu, 2 Nov 2017 12:21:10 +0100 (CET) | From | Thomas Gleixner <> | Subject | Re: [PATCH 02/23] x86, kaiser: do not set _PAGE_USER for init_mm page tables |
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On Thu, 2 Nov 2017, Andy Lutomirski wrote: > On Wed, Nov 1, 2017 at 2:28 PM, Thomas Gleixner <tglx@linutronix.de> wrote: > > On Wed, 1 Nov 2017, Andy Lutomirski wrote: > > > >> On Wed, Nov 1, 2017 at 2:11 PM, Thomas Gleixner <tglx@linutronix.de> wrote: > >> > On Tue, 31 Oct 2017, Dave Hansen wrote: > >> > > >> >> > >> >> init_mm is for kernel-exclusive use. If someone is allocating page > >> >> tables in it, do not set _PAGE_USER on them. This ensures that > >> >> we do *not* set NX on these page tables in the KAISER code. > >> > > >> > This changelog is confusing at best. > >> > > >> > Why is this a kaiser issue? Nothing should ever create _PAGE_USER entries > >> > in init_mm, right? > >> > >> The vsyscall page is _PAGE_USER and lives in init_mm via the fixmap. > > > > Groan, forgot about that abomination, but still there is no point in having > > it marked PAGE_USER in the init_mm at all, kaiser or not. > > > > How can it be PAGE_USER in user mms but not init_mm? It's the same page table.
Right you are. Brain was already shutdown it seems.
Thanks,
tglx
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