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a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20161025; h=x-gm-message-state:mime-version:references:in-reply-to:from:date :message-id:subject:to:cc; bh=42MaK4n6+CrelpQTjPFZO9NB2S0O1OTsWCtSJ9pIv6o=; b=lGmNAGjPVH7sOqo2dH4z0sUVysQ7PWUMAarrCjb+oswl+1rP8NRWThZ49I/+7WZyVK zdE7QEvpVWs6wy5B+cwYbRZmxO2MLPfcPEyoFX9T2kvmGNr9gwN25/Jc9Z9+Sx9X36jz sM6zXadbaVrT2ij8ijBvbry6eaOH9YTTr6r5LP6g9F2EB25mSzUy6I9+L5bvNKlUwXLP 6/a5747uJcSbOjPbuCTl1U0L/hfv0W2dSVQow1EI/DMUB5weTg/LmglYX6QE8bQGFB6+ u2qnFL5rbGBRvn+/7zL9xHVgv1j9ui1D/jCtM3vVsg+igbmt0xeaeT0pCuD9zCMF2Z3V jE8g== X-Gm-Message-State: APjAAAWHH/CJGKu5ZH/Tj1Ucc6Id04VtXF7dMhiULzXBK3MnfwfgrV6e 5DrQd20vRY6NOvDZ1DHL7p+rUvOBPJsrY7m+12gNdQ== X-Google-Smtp-Source: APXvYqyTw52gSQ4jw8pztzOwndZ0sk6pyQFwXTfytaf2zPfg719bU3sRcZ3Xjk3tkUfVqd3npa2/1rrBf+K/+C8JeGQ= X-Received: by 2002:a1f:4541:: with SMTP id s62mr12216061vka.59.1582143153200; Wed, 19 Feb 2020 12:12:33 -0800 (PST) MIME-Version: 1.0 References: <20191018161033.261971-1-samitolvanen@google.com> <20200219000817.195049-1-samitolvanen@google.com> <0386ecad-f3d6-f1dc-90da-7f05b2793839@arm.com> In-Reply-To: <0386ecad-f3d6-f1dc-90da-7f05b2793839@arm.com> From: Sami Tolvanen Date: Wed, 19 Feb 2020 12:12:21 -0800 Message-ID: Subject: Re: [PATCH v8 00/12] add support for Clang's Shadow Call Stack To: James Morse X-CRM114-Version: 20100106-BlameMichelson ( TRE 0.8.0 (BSD) ) MR-646709E3 X-CRM114-CacheID: sfid-20200219_121241_532238_3621A475 X-CRM114-Status: GOOD ( 11.23 ) 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: Mark Rutland , Kees Cook , Ard Biesheuvel , Masahiro Yamada , Marc Zyngier , Jann Horn , Nick Desaulniers , LKML , Steven Rostedt , Miguel Ojeda , clang-built-linux , Masami Hiramatsu , Catalin Marinas , Kernel Hardening , Laura Abbott , Will Deacon , Dave Martin , linux-arm-kernel Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Sender: "linux-arm-kernel" Errors-To: linux-arm-kernel-bounces+infradead-linux-arm-kernel=archiver.kernel.org@lists.infradead.org On Wed, Feb 19, 2020 at 10:38 AM James Morse wrote: > This looks like reserving x18 is causing Clang to not-inline the __kern_hyp_va() calls, > losing the vitally important section information. (I can see why the compiler thinks this > is fair) Thanks for catching this. This doesn't appear to be caused by reserving x18, it looks like SCS itself is causing clang to avoid inlining these. If I add __noscs to __kern_hyp_va(), clang inlines the function again. __always_inline also works, as you pointed out. > Is this a known, er, thing, with clang-9? I can reproduce this with ToT clang as well. > I suspect repainting all KVM's 'inline' with __always_inline will fix it. (yuck!) I'll try > tomorrow. I think switching to __always_inline is the correct solution here. Sami _______________________________________________ linux-arm-kernel mailing list linux-arm-kernel@lists.infradead.org http://lists.infradead.org/mailman/listinfo/linux-arm-kernel