Date: Thu, 6 Dec 2018 20:23:20 +0100 From: Ard Biesheuvel <ard.biesheuvel@...aro.org> To: Andy Lutomirski <luto@...nel.org> Cc: Will Deacon <will.deacon@....com>, Rick Edgecombe <rick.p.edgecombe@...el.com>, Nadav Amit <nadav.amit@...il.com>, Linux Kernel Mailing List <linux-kernel@...r.kernel.org>, Daniel Borkmann <daniel@...earbox.net>, Jessica Yu <jeyu@...nel.org>, Steven Rostedt <rostedt@...dmis.org>, Alexei Starovoitov <ast@...nel.org>, Linux-MM <linux-mm@...ck.org>, Jann Horn <jannh@...gle.com>, "Dock, Deneen T" <deneen.t.dock@...el.com>, Peter Zijlstra <peterz@...radead.org>, kristen@...ux.intel.com, Andrew Morton <akpm@...ux-foundation.org>, Ingo Molnar <mingo@...hat.com>, anil.s.keshavamurthy@...el.com, Kernel Hardening <kernel-hardening@...ts.openwall.com>, Masami Hiramatsu <mhiramat@...nel.org>, naveen.n.rao@...ux.vnet.ibm.com, "David S. Miller" <davem@...emloft.net>, "<netdev@...r.kernel.org>" <netdev@...r.kernel.org>, Dave Hansen <dave.hansen@...el.com> Subject: Re: [PATCH 1/2] vmalloc: New flag for flush before releasing pages On Thu, 6 Dec 2018 at 20:21, Andy Lutomirski <luto@...nel.org> wrote: > > On Thu, Dec 6, 2018 at 11:04 AM Ard Biesheuvel > <ard.biesheuvel@...aro.org> wrote: > > > > On Thu, 6 Dec 2018 at 19:54, Andy Lutomirski <luto@...nel.org> wrote: > > > > > > > That’s not totally nuts. Do we ever have code that expects __va() to > > > work on module data? Perhaps crypto code trying to encrypt static > > > data because our APIs don’t understand virtual addresses. I guess if > > > highmem is ever used for modules, then we should be fine. > > > > > > > The crypto code shouldn't care, but I think it will probably break hibernate :-( > > How so? Hibernate works (or at least should work) on x86 PAE, where > __va doesn't work on module data, and, on x86, the direct map has some > RO parts with where the module is, so hibernate can't be writing to > the memory through the direct map with its final permissions. On arm64 at least, hibernate reads the contents of memory via the linear mapping. Not sure about other arches.
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