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=-11.4 required=3.0 tests=DKIMWL_WL_MED,DKIM_SIGNED, DKIM_VALID,DKIM_VALID_AU,HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_PATCH, 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 06544CA9EA0 for ; Fri, 18 Oct 2019 17:54:43 +0000 (UTC) Received: from mother.openwall.net (mother.openwall.net [195.42.179.200]) by mail.kernel.org (Postfix) with SMTP id 4C9F6222C2 for ; Fri, 18 Oct 2019 17:54:42 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (2048-bit key) header.d=google.com header.i=@google.com header.b="pru8Y7xs" DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org 4C9F6222C2 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-17050-kernel-hardening=archiver.kernel.org@lists.openwall.com Received: (qmail 12025 invoked by uid 550); 18 Oct 2019 17:54:33 -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 20413 invoked from network); 18 Oct 2019 17:05:42 -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=x6GpsgHPaenSyC5p+IrYQknWia4lKY0B5Vf4l4gdQSw=; b=pru8Y7xsWSIdqZR1UXLglz64NrdFImykv1hpXma1k378qh9GF0SPliCcyZB8vMX7gE X3PfTswubuOthM8DCa4MKuMqqB1ZfOPHIhuEN9TMHd7OTZoscSb0DkIwcKzx/zVRsRzZ QpVsX696Og4ZxdvD3yeFj/AnBmqkJaxHpcBabDgxa1/06jnOKR4SPg62RTTmmQ52t+8S vOzXu4T6IK5JJ+sLrpw1VPCRku6gZS08n7Kckhw2KqDpdWTQICKrAUvwcmSbe2WDexT6 KcVKUWL1M2hSYKLv2USJ9PsVEnaLnEqc22VydBFXRMPGh4AiAOA8mz7cgBZHgxDEDolP r6Cg== 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=x6GpsgHPaenSyC5p+IrYQknWia4lKY0B5Vf4l4gdQSw=; b=Q2fItQw3FHhJEoySSghoIYtd5T3vL4vaFWTWnaK9K3wiMjSUo/JFRKig0A7u0prf6y L+saVxiqVRgWr2T7eEkLbt104QugV+JON4pHSKC0jfIAHcHXLi11m+Ol5Y/ufiaoTMBn QGD8qokjqN6mMHqSXPRVNK6VJlB6aBiBMsjgIz1X8BwoW0jnM/Kb6DgUQO1nl2nAZNgh EswbVf9RQDQyTYfG/Q17D90/nMemn8NsS0arpCXVv3r0K2JWoB+y/HQECUkkgIxwV7zW F946Qwixjdd9obPJFrGhTJx/tjxHNkURBZzXUIZGeuG78Eww+NfzeTf+1QDSAAllEg80 47GA== X-Gm-Message-State: APjAAAVyWFjv3Xu74kjvAor4BZuycBGwgOmn41KjA6x8+Qw4p7RGaoRj GcMMssfhK7fT+IwLGUQBi5N9ya03rrGNnAoirXxPQQ== X-Google-Smtp-Source: APXvYqwYzSrQhNESR2odZjGb7CA2wtjkk8PIj6W3+g28TbncpOPsZUdRhuZ5AejLhrFJsW3Q8+X1IzSvMoqY0M2m7JA= X-Received: by 2002:a67:ffc7:: with SMTP id w7mr6159173vsq.15.1571418330160; Fri, 18 Oct 2019 10:05:30 -0700 (PDT) MIME-Version: 1.0 References: <20191018161033.261971-1-samitolvanen@google.com> <20191018161033.261971-14-samitolvanen@google.com> In-Reply-To: From: Sami Tolvanen Date: Fri, 18 Oct 2019 10:05:18 -0700 Message-ID: Subject: Re: [PATCH 13/18] arm64: preserve x18 when CPU is suspended To: Nick Desaulniers Cc: Will Deacon , Catalin Marinas , Steven Rostedt , Ard Biesheuvel , Dave Martin , Kees Cook , Laura Abbott , Mark Rutland , clang-built-linux , Kernel Hardening , Linux ARM , LKML Content-Type: text/plain; charset="UTF-8" On Fri, Oct 18, 2019 at 9:49 AM Nick Desaulniers wrote: > > diff --git a/arch/arm64/mm/proc.S b/arch/arm64/mm/proc.S > > index fdabf40a83c8..9a8bd4bc8549 100644 > > --- a/arch/arm64/mm/proc.S > > +++ b/arch/arm64/mm/proc.S > > @@ -73,6 +73,9 @@ alternative_endif > > stp x8, x9, [x0, #48] > > stp x10, x11, [x0, #64] > > stp x12, x13, [x0, #80] > > +#ifdef CONFIG_SHADOW_CALL_STACK > > + stp x18, xzr, [x0, #96] > > Could this be a str/ldr of just x18 rather than stp/ldp of x18 + > garbage? Maybe there's no real cost difference, or some kind of > alignment invariant? Sure, this can be changed to str/ldr. I don't think there's a noticeable difference in cost. Sami