From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-8.3 required=3.0 tests=DKIMWL_WL_MED,DKIM_SIGNED, DKIM_VALID,DKIM_VALID_AU,HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI, SPF_HELO_NONE,SPF_PASS,URIBL_BLOCKED,USER_IN_DEF_DKIM_WL autolearn=no autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id 75279CA9EC9 for ; Mon, 4 Nov 2019 23:45:09 +0000 (UTC) Received: from mother.openwall.net (mother.openwall.net [195.42.179.200]) by mail.kernel.org (Postfix) with SMTP id BE6A4214E0 for ; Mon, 4 Nov 2019 23:45:08 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (2048-bit key) header.d=google.com header.i=@google.com header.b="XWr7kryZ" DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org BE6A4214E0 Authentication-Results: mail.kernel.org; dmarc=fail (p=reject dis=none) header.from=google.com Authentication-Results: mail.kernel.org; spf=pass smtp.mailfrom=kernel-hardening-return-17280-kernel-hardening=archiver.kernel.org@lists.openwall.com Received: (qmail 3933 invoked by uid 550); 4 Nov 2019 23:45:03 -0000 Mailing-List: contact kernel-hardening-help@lists.openwall.com; run by ezmlm Precedence: bulk List-Post: List-Help: List-Unsubscribe: List-Subscribe: List-ID: Received: (qmail 3907 invoked from network); 4 Nov 2019 23:45:02 -0000 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=google.com; s=20161025; h=mime-version:references:in-reply-to:from:date:message-id:subject:to :cc; bh=SpNwJfSJO9MidRCrn2p9uupIwuhjvEPSgYuh9TBYZuw=; b=XWr7kryZXstmsXgYE4dBJ4NrnDur3s/AC0seExuiGF6z4UGQCwWfIPFNeY7JeVwPM3 wnP1G5A/K76IWU2DyV/IUlCtYDCgPO0n/bDVtTP4pu+zHCoH+fei6dyO2OcLB2gsC6W7 yHM2c0/FUmsEcEYZY0y9ta70pnWbez+C+rMSFS+aiM6DHbB5OA98h3MrtmOeV6q9EDtK bw1zfaHUujqN+zHGVRnnbiam+tcW3d2rc3/Pvust522b4CCrQ9v9kAdVmg3Axk3wD37y xqCPcphfjtbZ+wkJQy35r/dA4lS8knkpiqdmkjVq1MbYxp8Jbw1P5SRRjv/N4BJhioPs zRZg== X-Google-DKIM-Signature: v=1; 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=SpNwJfSJO9MidRCrn2p9uupIwuhjvEPSgYuh9TBYZuw=; b=dYoO31ZJURDZtbIxvCvcF9dGwFV4P2HVvycggNV0f3Ylwf07QfG/NIdrmPg8Ia+yc7 iSUcn96CzLq9/Bj+tqToUWNSoWxbf7+/vnNL1ZsM/+fwjwcCL85M2GYcL9U7mlcd2eZz /dwhhvne/oYMv6uJSprEcUiwuo7CRs5TcM4vGwK65/tpxILn0zC/ntnM7zpqVlIeCO8D f3Yh/qGLGsaEyqNU+Jw7eoJrP5uJL/pKtCrQiScpijVhjNmYXMNs6Km6maRgXf6mZRpi MxtzlcAkwzGq9PASjWQAqKVz6c05bQ7Ee/yq7REb7t/jMy+Ufv7jp/CQqtwUoD3r2tZA +YLg== X-Gm-Message-State: APjAAAXGFCWRdbdNBNmsiI7AjqvwQgrNPNr8Y1sPRXp+4iinuFKicBze kwx8Klhxb1oT2X3B7+dFnofZeLLrbCtuFqqqOmdS/g== X-Google-Smtp-Source: APXvYqwMrHXnmCbhr/Nl5pMJrYHuxKP6Lu2UQKV7ItSK55vLCW1x6A4Use4SMcLe4G85I9Dvt99c2soxGNjz4r8rNRQ= X-Received: by 2002:ab0:4587:: with SMTP id u7mr3850575uau.67.1572911090684; Mon, 04 Nov 2019 15:44:50 -0800 (PST) MIME-Version: 1.0 References: <20191018161033.261971-1-samitolvanen@google.com> <20191101221150.116536-1-samitolvanen@google.com> <20191101221150.116536-12-samitolvanen@google.com> <20191104171132.GB2024@lakrids.cambridge.arm.com> In-Reply-To: <20191104171132.GB2024@lakrids.cambridge.arm.com> From: Sami Tolvanen Date: Mon, 4 Nov 2019 15:44:39 -0800 Message-ID: Subject: Re: [PATCH v4 11/17] arm64: disable function graph tracing with SCS To: Mark Rutland Cc: Will Deacon , Catalin Marinas , Steven Rostedt , Masami Hiramatsu , Ard Biesheuvel , Dave Martin , Kees Cook , Laura Abbott , Marc Zyngier , Nick Desaulniers , Jann Horn , Miguel Ojeda , Masahiro Yamada , clang-built-linux , Kernel Hardening , linux-arm-kernel , LKML Content-Type: text/plain; charset="UTF-8" On Mon, Nov 4, 2019 at 9:11 AM Mark Rutland wrote: > Can you please elaborate on _how_ this is incompatible in the commit > message? > > For example, it's not clear to me if you mean that's functionally > incompatible, or if you're trying to remove return-altering gadgets. > > If there's a functional incompatibility, please spell that out a bit > more clearly. Likewise if this is about minimizing the set of places > that can mess with control-flow outside of usual function conventions. Sure, I'll add a better description in v5. In this case, the return address is modified in the kernel stack, which means the changes are ignored with SCS. Sami