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=-8.4 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,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 33A82CA9EA0 for ; Tue, 22 Oct 2019 21:46:17 +0000 (UTC) Received: from mother.openwall.net (mother.openwall.net [195.42.179.200]) by mail.kernel.org (Postfix) with SMTP id 705532053B for ; Tue, 22 Oct 2019 21:46:16 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (2048-bit key) header.d=google.com header.i=@google.com header.b="e7GEnWKd" DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org 705532053B 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-17094-kernel-hardening=archiver.kernel.org@lists.openwall.com Received: (qmail 5912 invoked by uid 550); 22 Oct 2019 21:46:09 -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 5891 invoked from network); 22 Oct 2019 21:46:09 -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=aMrKTryhNXEL/B3UTp309ZugYMIYjNFJ3JCQDb7MpUg=; b=e7GEnWKdbrItjF4U3+0nKF/lx06Wuk/tgdQ9ljPjtYqFQxUxKdNDAzX4a3J6VJRTNe fvZtiXWCwgTHkznQdje8cmtubTkLp7iAWQx8JQFReAwrsWNXsaolV9s3JWeGTMMfUgSg /repYwQIO6djr64TXfPZeXSpbh0xxoZWJHDJcfD+y+CBwuzbqN5LUnqOWUTiGUf9R0Qr mx9Cap4UGrAAnISWvG3FD7dZFNO0uJ247ZJQzIRI+2iGU4ea2aaoSxUg8M9zDlq777fS qDyNrdBaDb9pA7+swtiQSKBEfo7e0BGKpeLpbQo3G6PYa3kXJxBuLrIskMILqlTGUpAh 147A== 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=aMrKTryhNXEL/B3UTp309ZugYMIYjNFJ3JCQDb7MpUg=; b=IrK4g9qIEFE4msW1NDhIyUxfBeSIYtAUudVWifJI2nwq4IisLKop5Winc45MV0ewHH qQoW1a3of8ju4IjByLDAqs8Fpr9KO+NmE6ECwnz/hv8pBT3q0ap1sPzs11jy+sLjV5yx zNdY97aOJX31oNs0wFcOw4+ovePm+YPic1gSEFGWYAydgigo7dZfvvCuuqMYhH8J5plH s1M7XSVac2SepK4jTRrO10Y35Ah6n43l+bsx2teutQpDo/5mSC/ApCdJooJT7HLVWIK+ /+1ZEA5TWU3i7hNa9jK+Y6SA+p2+8UmYi85OorwEBHCAur8U7G4z1e9tGBYQVaqSI6gI IhHw== X-Gm-Message-State: APjAAAXckpyLqFsybh1XjwbE3UlQe2QJkqoaMSuQ+pumeiOe06UVVwQk vYM3gQJX/o1oKUEgQ5r7Xj30mNt+4glrC8bycyVIrg== X-Google-Smtp-Source: APXvYqzBN7l8ISCANHOSmoQVZ7BSwt3ADui9uc+L7MwmUC/V+3k+jtXG0/+Q6ONVrUpOvA8D2yYjNueSFsMjPD9iN3Q= X-Received: by 2002:a1f:a5d8:: with SMTP id o207mr3327674vke.81.1571780756763; Tue, 22 Oct 2019 14:45:56 -0700 (PDT) MIME-Version: 1.0 References: <20191018161033.261971-1-samitolvanen@google.com> <20191018161033.261971-4-samitolvanen@google.com> <20191022182206.0d8b2301@why> In-Reply-To: <20191022182206.0d8b2301@why> From: Sami Tolvanen Date: Tue, 22 Oct 2019 14:45:45 -0700 Message-ID: Subject: Re: [PATCH 03/18] arm64: kvm: stop treating register x18 as caller save To: Marc Zyngier Cc: Will Deacon , Catalin Marinas , Steven Rostedt , Ard Biesheuvel , Mark Rutland , Kees Cook , Kernel Hardening , Nick Desaulniers , LKML , clang-built-linux , Laura Abbott , Dave Martin , linux-arm-kernel Content-Type: text/plain; charset="UTF-8" On Tue, Oct 22, 2019 at 10:22 AM Marc Zyngier wrote: > > .macro save_callee_saved_regs ctxt > > + str x18, [\ctxt, #CPU_XREG_OFFSET(18)] > > stp x19, x20, [\ctxt, #CPU_XREG_OFFSET(19)] > > stp x21, x22, [\ctxt, #CPU_XREG_OFFSET(21)] > > stp x23, x24, [\ctxt, #CPU_XREG_OFFSET(23)] > > @@ -38,6 +39,7 @@ > > ldp x25, x26, [\ctxt, #CPU_XREG_OFFSET(25)] > > ldp x27, x28, [\ctxt, #CPU_XREG_OFFSET(27)] > > ldp x29, lr, [\ctxt, #CPU_XREG_OFFSET(29)] > > + ldr x18, [\ctxt, #CPU_XREG_OFFSET(18)] > > There is now an assumption that ctxt is x18 (otherwise why would it be > out of order?). Please add a comment to that effect. > > - // Restore guest regs x19-x29, lr > > + // Restore guest regs x18-x29, lr > > restore_callee_saved_regs x18 > > Or you could elect another register such as x29 as the base, and keep > the above in a reasonable order. I'm fine with either option. Ard, any thoughts? Sami