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Fri, 04 Sep 2020 00:14:12 -0700 (PDT) Date: Fri, 4 Sep 2020 00:14:11 -0700 From: Nathan Chancellor To: Arvind Sankar Subject: Re: [PATCH v2 01/28] x86/boot/compressed: Disable relocation relaxation Message-ID: <20200904071411.GA1712031@ubuntu-n2-xlarge-x86> References: <20200624203200.78870-1-samitolvanen@google.com> <20200903203053.3411268-1-samitolvanen@google.com> <20200903203053.3411268-2-samitolvanen@google.com> <202009031444.F2ECA89E@keescook> <20200903234215.GA106172@rani.riverdale.lan> MIME-Version: 1.0 Content-Disposition: inline In-Reply-To: <20200903234215.GA106172@rani.riverdale.lan> X-CRM114-Version: 20100106-BlameMichelson ( TRE 0.8.0 (BSD) ) MR-646709E3 X-CRM114-CacheID: sfid-20200904_031416_089066_A21A716C X-CRM114-Status: GOOD ( 21.91 ) X-BeenThere: linux-arm-kernel@lists.infradead.org X-Mailman-Version: 2.1.29 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Cc: linux-arch@vger.kernel.org, x86@kernel.org, Kees Cook , "Paul E. McKenney" , kernel-hardening@lists.openwall.com, Peter Zijlstra , Greg Kroah-Hartman , Masahiro Yamada , linux-kbuild@vger.kernel.org, Nick Desaulniers , linux-kernel@vger.kernel.org, Steven Rostedt , clang-built-linux@googlegroups.com, Sami Tolvanen , linux-pci@vger.kernel.org, Will Deacon , linux-arm-kernel@lists.infradead.org Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Sender: "linux-arm-kernel" Errors-To: linux-arm-kernel-bounces+linux-arm-kernel=archiver.kernel.org@lists.infradead.org On Thu, Sep 03, 2020 at 07:42:15PM -0400, Arvind Sankar wrote: > On Thu, Sep 03, 2020 at 02:44:41PM -0700, Kees Cook wrote: > > On Thu, Sep 03, 2020 at 01:30:26PM -0700, Sami Tolvanen wrote: > > > From: Arvind Sankar > > > > > > Patch series [4] is a solution to allow the compressed kernel to be > > > linked with -pie unconditionally, but even if merged is unlikely to be > > > backported. As a simple solution that can be applied to stable as well, > > > prevent the assembler from generating the relaxed relocation types using > > > the -mrelax-relocations=no option. For ease of backporting, do this > > > unconditionally. > > > > > > [0] https://gitlab.com/x86-psABIs/x86-64-ABI/-/blob/master/x86-64-ABI/linker-optimization.tex#L65 > > > [1] https://lore.kernel.org/lkml/20200807194100.3570838-1-ndesaulniers@google.com/ > > > [2] https://github.com/ClangBuiltLinux/linux/issues/1121 > > > [3] https://reviews.llvm.org/rGc41a18cf61790fc898dcda1055c3efbf442c14c0 > > > [4] https://lore.kernel.org/lkml/20200731202738.2577854-1-nivedita@alum.mit.edu/ > > > > > > Reported-by: Nick Desaulniers > > > Signed-off-by: Arvind Sankar > > > > Reviewed-by: Kees Cook > > > > -- > > Kees Cook > > Note that since [4] is now in tip, assuming it doesn't get dropped for > some reason, this patch isn't necessary unless you need to backport this > LTO series to 5.9 or below. > > Thanks. It is still necessary for tip of tree LLVM to work properly (specifically clang and ld.lld) regardless of whether or not LTO is used. [4] also fixes it but I don't think it can be backported to stable so it would still be nice to get it picked up so that it can be sent back there. We have been carrying it in our CI for a decent amount of time... Cheers, Nathan _______________________________________________ linux-arm-kernel mailing list linux-arm-kernel@lists.infradead.org http://lists.infradead.org/mailman/listinfo/linux-arm-kernel