From mboxrd@z Thu Jan 1 00:00:00 1970 Return-path: Date: Fri, 3 Feb 2017 11:51:59 +0000 From: Mark Rutland Subject: Re: [PATCH v31 05/12] arm64: kdump: protect crash dump kernel memory Message-ID: <20170203115158.GD30497@leverpostej> References: <20170201124218.5823-1-takahiro.akashi@linaro.org> <20170201124630.6016-4-takahiro.akashi@linaro.org> <20170201180008.GG4756@leverpostej> <20170201182506.GA30584@leverpostej> <20170202103905.GF13549@linaro.org> <20170202115425.GJ31394@leverpostej> <20170203014538.GA29585@linaro.org> MIME-Version: 1.0 Content-Disposition: inline In-Reply-To: <20170203014538.GA29585@linaro.org> List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Sender: "kexec" Errors-To: kexec-bounces+dwmw2=infradead.org@lists.infradead.org To: AKASHI Takahiro , geoff@infradead.org, catalin.marinas@arm.com, will.deacon@arm.com, james.morse@arm.com, bauerman@linux.vnet.ibm.com, dyoung@redhat.com, kexec@lists.infradead.org, linux-arm-kernel@lists.infradead.org Hi, On Fri, Feb 03, 2017 at 10:45:39AM +0900, AKASHI Takahiro wrote: > On Thu, Feb 02, 2017 at 11:54:25AM +0000, Mark Rutland wrote: > > On Thu, Feb 02, 2017 at 07:39:06PM +0900, AKASHI Takahiro wrote: > > > On Wed, Feb 01, 2017 at 06:25:06PM +0000, Mark Rutland wrote: > > > > On Wed, Feb 01, 2017 at 06:00:08PM +0000, Mark Rutland wrote: > > > > Another question is (how) does hyp map this region? > > > > > > I don't get your point here. > > > Hyp mode does care only physical memory in intermediate address, doesn't it? > > > > My concern was that hyp may map the region; and thus buggy code at hyp > > can corrupt the region (and/or hyp may conflict w.r.t. attributes). > > Grep'ing create_hyp_mappings() under arch/arm(64)/kvm shows that > we have only a few small regions of memory mapped in hyp mode. > I also confirmed that there is no active mapping for crash dump kernel > memory by checking mmu tables with DS-5 debugger. Ok, that sounds fine. I was under the mistaken impression that hyp had a copy of the whole linear mapping, but it seems it lazily maps that in (at page granularity) as required. So there should be no alias for the crashkernel region. > > We mght have to ensure hyp doesn't map the crashkernel region, and to > > case us pain, disallow freeing of any part of the region. > > So I don't believe we need to worry such a case. I agree. Thanks, Mark. _______________________________________________ kexec mailing list kexec@lists.infradead.org http://lists.infradead.org/mailman/listinfo/kexec