From mboxrd@z Thu Jan 1 00:00:00 1970 From: mark.rutland@arm.com (Mark Rutland) Date: Thu, 1 Jun 2017 17:52:06 +0100 Subject: [PATCH 3/4] arm64/kasan: don't allocate extra shadow memory In-Reply-To: References: <20170601162338.23540-1-aryabinin@virtuozzo.com> <20170601162338.23540-3-aryabinin@virtuozzo.com> <20170601163442.GC17711@leverpostej> Message-ID: <20170601165205.GA8191@leverpostej> To: linux-arm-kernel@lists.infradead.org List-Id: linux-arm-kernel.lists.infradead.org On Thu, Jun 01, 2017 at 06:45:32PM +0200, Dmitry Vyukov wrote: > On Thu, Jun 1, 2017 at 6:34 PM, Mark Rutland wrote: > > On Thu, Jun 01, 2017 at 07:23:37PM +0300, Andrey Ryabinin wrote: > >> We used to read several bytes of the shadow memory in advance. > >> Therefore additional shadow memory mapped to prevent crash if > >> speculative load would happen near the end of the mapped shadow memory. > >> > >> Now we don't have such speculative loads, so we no longer need to map > >> additional shadow memory. > > > > I see that patch 1 fixed up the Linux helpers for outline > > instrumentation. > > > > Just to check, is it also true that the inline instrumentation never > > performs unaligned accesses to the shadow memory? > > Inline instrumentation generally accesses only a single byte. Sorry to be a little pedantic, but does that mean we'll never access the additional shadow, or does that mean it's very unlikely that we will? I'm guessing/hoping it's the former! Thanks, Mark.