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 8623AC33CAF for ; Thu, 16 Jan 2020 21:58:23 +0000 (UTC) Received: from mother.openwall.net (mother.openwall.net [195.42.179.200]) by mail.kernel.org (Postfix) with SMTP id D19B320728 for ; Thu, 16 Jan 2020 21:58:22 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (2048-bit key) header.d=google.com header.i=@google.com header.b="VNVb2CG8" DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org D19B320728 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-17582-kernel-hardening=archiver.kernel.org@lists.openwall.com Received: (qmail 19856 invoked by uid 550); 16 Jan 2020 21:58:17 -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 19835 invoked from network); 16 Jan 2020 21:58:16 -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=90kSKrsPpbCluN0U4RDiVNxyzvDrsXuzgr4VAEgKFuc=; b=VNVb2CG8c3HkjMqddLo98y3OPZa+WSPTAgoYdSf7FbWI5WNi3wnlLK0p32BzwbDJkl DxW3dVwqqXEzvQDJ/t2t8XVh7UcdBnxl57fQBAwB07GY+Kc5s2di8Ti7bcTy/S2/pe8U ishyY7KqIu0u9X9VZYcJD0ArT3LnkwpSs93Icdin/XOuAUh49RrudpoY+q52GTTYSx40 GpnMdqP6bRbODHeQRjbKNwwaXhmlW1mB68/yoKkEelegSKWRaD4DkiQa+ct5BY9CQ8b+ WhW5jUQJ1e+6OM3m0IRmGb8dXhOkx9FNog8QbWSOqQkVjep7R9pRuyilDTthUXsbS/HD LriA== 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=90kSKrsPpbCluN0U4RDiVNxyzvDrsXuzgr4VAEgKFuc=; b=WzsGcptnnp7rdsGshr83Hi9907lR2RMNa6/CorrSfhMXPP1YBNJz+OPTwE9y9BFroq T2+vfsWJIZM3iKaeF/c1gIJuh/wGGgn9qElVLa3ifZ9wIWSWqYaQYO0zOKUx8HoKjbob ArHRtN7rIx404fTQAIjepYYivU6OV6B5PlRAjYMzP27HfkILXj05zVaS7gYtRgM1fiCI 2aqHs6Bxk7bEyTTyrd0a+HQ5bJwj9dYdoZhB/ZqgYcuxz4BnGVRksJq6bBdQlo1/ugVl oBHLWhdVcqniQB9jegkbrtyDBbJstYYzhDpWf3eJFE704HwQzZRgCZbONZhpXXruW3a1 GaUw== X-Gm-Message-State: APjAAAUzO5phYJeasookRlvTwHeo1GlRtgrc2Y+FGrqcWKOM57LDoDAj Al1amaN27DQQJnt1/izK3rFGNKC0YGfsoEd7OyPsTw== X-Google-Smtp-Source: APXvYqzrUqH5/W2UZ+FeXG0hZr7Tack1J9k9eB9pBix6w41rOK+OkTqsOrnRDdc5aMPEGFoHQeXxcn/0tewoHbFlgSg= X-Received: by 2002:a67:ae43:: with SMTP id u3mr3413809vsh.44.1579211884786; Thu, 16 Jan 2020 13:58:04 -0800 (PST) MIME-Version: 1.0 References: <20191018161033.261971-1-samitolvanen@google.com> <20191206221351.38241-1-samitolvanen@google.com> <20191206221351.38241-15-samitolvanen@google.com> <20200116182414.GC22420@willie-the-truck> In-Reply-To: <20200116182414.GC22420@willie-the-truck> From: Sami Tolvanen Date: Thu, 16 Jan 2020 13:57:53 -0800 Message-ID: Subject: Re: [PATCH v6 14/15] arm64: implement Shadow Call Stack To: Will Deacon Cc: Catalin Marinas , Steven Rostedt , Masami Hiramatsu , Ard Biesheuvel , Mark Rutland , 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 Thu, Jan 16, 2020 at 10:24 AM Will Deacon wrote: > > .macro irq_stack_entry > > mov x19, sp // preserve the original sp > > +#ifdef CONFIG_SHADOW_CALL_STACK > > + mov x20, x18 // preserve the original shadow stack > > +#endif > > Hmm, not sure about corrupting x20 here. Doesn't it hold the PMR value from > kernel_entry? You're right, and it's used in el1_irq after irq_handler if CONFIG_ARM64_PSEUDO_NMI is enabled. Thanks for pointing this out. Looks like one of x24-x29 should be safe here, and the comment needs to be updated to explain why x20-x23 shouldn't be corrupted. Sami