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Wed, 24 Jun 2020 16:40:04 -0700 (PDT) Date: Wed, 24 Jun 2020 16:39:59 -0700 From: Sami Tolvanen To: Nick Desaulniers Subject: Re: [PATCH 17/22] arm64: vdso: disable LTO Message-ID: <20200624233959.GB94769@google.com> References: <20200624203200.78870-1-samitolvanen@google.com> <20200624203200.78870-18-samitolvanen@google.com> <20200624215231.GC120457@google.com> MIME-Version: 1.0 Content-Disposition: inline In-Reply-To: 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 , "maintainer:X86 ARCHITECTURE \(32-BIT AND 64-BIT\)" , Kees Cook , "Paul E. McKenney" , Kernel Hardening , Greg Kroah-Hartman , Masahiro Yamada , Linux Kbuild mailing list , LKML , clang-built-linux , linux-pci@vger.kernel.org, Will Deacon , Linux ARM 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 Wed, Jun 24, 2020 at 04:05:48PM -0700, Nick Desaulniers wrote: > On Wed, Jun 24, 2020 at 2:52 PM Sami Tolvanen wrote: > > > > On Wed, Jun 24, 2020 at 01:58:57PM -0700, 'Nick Desaulniers' via Clang Built Linux wrote: > > > On Wed, Jun 24, 2020 at 1:33 PM Sami Tolvanen wrote: > > > > > > > > Filter out CC_FLAGS_LTO for the vDSO. > > > > > > Just curious about this patch (and the following one for x86's vdso), > > > do you happen to recall specifically what the issues with the vdso's > > > are? > > > > I recall the compiler optimizing away functions at some point, but as > > LTO is not really needed in the vDSO, it's just easiest to disable it > > there. > > Sounds fishy; with extern linkage then I would think it's not safe to > eliminate functions. Probably unnecessary for the initial > implementation, and something we can follow up on, but always good to > have an answer to the inevitable question "why?" in the commit > message. Sure. I can test this again with the current toolchain to see if there are still problems. Sami _______________________________________________ linux-arm-kernel mailing list linux-arm-kernel@lists.infradead.org http://lists.infradead.org/mailman/listinfo/linux-arm-kernel