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Date: Wed, 1 Nov 2017 22:28:26 +0100 (CET) From: Thomas Gleixner <tglx@...utronix.de> To: Andy Lutomirski <luto@...nel.org> cc: Dave Hansen <dave.hansen@...ux.intel.com>, "linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>, "linux-mm@...ck.org" <linux-mm@...ck.org>, moritz.lipp@...k.tugraz.at, Daniel Gruss <daniel.gruss@...k.tugraz.at>, michael.schwarz@...k.tugraz.at, Linus Torvalds <torvalds@...ux-foundation.org>, Kees Cook <keescook@...gle.com>, Hugh Dickins <hughd@...gle.com>, X86 ML <x86@...nel.org> Subject: Re: [PATCH 02/23] x86, kaiser: do not set _PAGE_USER for init_mm page tables On Wed, 1 Nov 2017, Andy Lutomirski wrote: > On Wed, Nov 1, 2017 at 2:11 PM, Thomas Gleixner <tglx@...utronix.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. Thanks, tglx
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