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[46.139.12.213]) by smtp.gmail.com with ESMTPSA id q124sm26547015wma.5.2019.10.07.06.09.44 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Mon, 07 Oct 2019 06:09:44 -0700 (PDT) Date: Mon, 7 Oct 2019 15:09:42 +0200 From: Ingo Molnar To: Hans de Goede Cc: Arvind Sankar , linux-kernel@vger.kernel.org, x86@kernel.org, Borislav Petkov , Thomas Gleixner Subject: Re: kexec breaks with 5.4 due to memzero_explicit Message-ID: <20191007130942.GA82950@gmail.com> References: <20191007030939.GB5270@rani.riverdale.lan> <28f3d204-47a2-8b4f-f6a7-11d73c2d87c8@redhat.com> <0f083019-61e8-7ed5-dde7-99e1aa363d9c@redhat.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <0f083019-61e8-7ed5-dde7-99e1aa363d9c@redhat.com> User-Agent: Mutt/1.10.1 (2018-07-13) Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org * Hans de Goede wrote: > Hi, > > On 07-10-2019 10:50, Hans de Goede wrote: > > Hi, > > > > On 07-10-2019 05:09, Arvind Sankar wrote: > > > Hi, arch/x86/purgatory/purgatory.ro has an undefined symbol > > > memzero_explicit. This has come from commit 906a4bb97f5d ("crypto: > > > sha256 - Use get/put_unaligned_be32 to get input, memzero_explicit") > > > according to git bisect. > > > > Hmm, it (obviously) does build for me and using kexec still also works > > for me. > > > > But it seems that you are right and that this should not build, weird. > > Ok, I understand now, it seems that the kernel will happily build with > undefined symbols in the purgatory and my kexec testing did not hit > the sha256 check path (*) so it did not crash. I can reproduce this before my patch: > > [hans@shalem linux]$ ld arch/x86/purgatory/purgatory.ro > ld: warning: cannot find entry symbol _start; defaulting to 0000000000401000 > ld: arch/x86/purgatory/purgatory.ro: in function `sha256_transform': > sha256.c:(.text+0x1c0c): undefined reference to `memzero_explicit' I've applied your fix, but would it make sense to also integrate this linker test in the regular build with a second patch, to make sure something similar doesn't occur again? Thanks, Ingo