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=-6.8 required=3.0 tests=DKIM_SIGNED,DKIM_VALID, DKIM_VALID_AU,HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_PATCH,MAILING_LIST_MULTI, SIGNED_OFF_BY,SPF_HELO_NONE,SPF_PASS,URIBL_BLOCKED autolearn=ham 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 84349CA9EB5 for ; Mon, 21 Oct 2019 06:20:59 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 56168206C2 for ; Mon, 21 Oct 2019 06:20:59 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (2048-bit key) header.d=linaro.org header.i=@linaro.org header.b="h6kY1+sn" Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1727106AbfJUGU6 (ORCPT ); Mon, 21 Oct 2019 02:20:58 -0400 Received: from mail-wr1-f65.google.com ([209.85.221.65]:39614 "EHLO mail-wr1-f65.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726039AbfJUGU5 (ORCPT ); Mon, 21 Oct 2019 02:20:57 -0400 Received: by mail-wr1-f65.google.com with SMTP id c6so165646wrm.6 for ; Sun, 20 Oct 2019 23:20:54 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=linaro.org; s=google; h=mime-version:references:in-reply-to:from:date:message-id:subject:to :cc; bh=CdvcOGCYVL+T0dd/Qovdpy0EycQbYWDHOCHJnmgemls=; b=h6kY1+snCa9b1x7e/EgIjsAXXWChcSe7Uw0FjL6G+anKZpluVsnHZlfXHSt09rzA17 7QEgstgPbNp7zGit5Kg6IcWlVJCjEQWPZhijlHGqzE9gZYmdrNfkbUvmJSjt7J9BNrVI iBrcqQELNZQolZpgXvm2krI6QCIE+5auETUijcAYUxxeV14FrPjKGIpTjQQ1uW5xGnK2 rB//6di6mnksNQgm1xPuAgR98MBRjT/PtPVc/7XVHsjRva7gRDw9sCzJA2LXB2t3ypJ8 2klWs/YFyTytVptXjN8BopBVvxJrkKyMYaLh0RglRJd0PZbT5T5vpgEG/gQbOEjzJNvh 219Q== 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=CdvcOGCYVL+T0dd/Qovdpy0EycQbYWDHOCHJnmgemls=; b=mW4b84x3MCbhxr1hP0dL9EWCbWoGM/UFBSCbVH3lxXa4JAUbWuyh4wTCi5f8G7/Mb0 2Vn19zW43iZj/bvVmUJqQ6Vc2oIkFHs4/uJJ8kqIQ7TH17SVj66MjpVsueuQHj9lNJzs MMYfxchz6RcObs3nPwfC+Lf1xVHW4EAQs22Ujd53j9q318gbAMWQTowxmcHz6fuCkQo1 Vmd549WAeQkdnveBU0uiZ6u3QaK89mEvf0dRu1q4aHs+otbVYfo5KDVHswSrQtDA0s9Q KnqbLecYXsknQZ4ESpJ4gwuxTEQud4OKzvxl78S/Zuxog6DYWGjZqRaU3bSsuc70ul8Q SYcQ== X-Gm-Message-State: APjAAAVnYCjlXTd8xjzt7vtYA4VJvEzKaG0MlQ6deTfmpY+ivUMKF6BD SjLI7PPI0foGiqm2GvJkRNfZaqjbqPs3NrFP4yGsWQ== X-Google-Smtp-Source: APXvYqy24wsGU0Cj+4SmHZlaSf1uaZpL2g4+f87/+EJ/1iZO4TCaFGyxMrU8YBrf0ThCHUcVzuLjkwXTWadLECQwLMk= X-Received: by 2002:a5d:43c9:: with SMTP id v9mr11140606wrr.200.1571638854218; Sun, 20 Oct 2019 23:20:54 -0700 (PDT) MIME-Version: 1.0 References: <20191018161033.261971-1-samitolvanen@google.com> <20191018161033.261971-15-samitolvanen@google.com> In-Reply-To: <20191018161033.261971-15-samitolvanen@google.com> From: Ard Biesheuvel Date: Mon, 21 Oct 2019 08:20:43 +0200 Message-ID: Subject: Re: [PATCH 14/18] arm64: efi: restore x18 if it was corrupted To: Sami Tolvanen Cc: Will Deacon , Catalin Marinas , Steven Rostedt , Dave Martin , Kees Cook , Laura Abbott , Mark Rutland , Nick Desaulniers , clang-built-linux , Kernel Hardening , linux-arm-kernel , Linux Kernel Mailing List Content-Type: text/plain; charset="UTF-8" Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Fri, 18 Oct 2019 at 18:11, Sami Tolvanen wrote: > > If we detect a corrupted x18 and SCS is enabled, restore the register > before jumping back to instrumented code. > You'll have to elaborate a bit here and explain that this is sufficient, given that we run EFI runtime services with interrupts enabled. > Signed-off-by: Sami Tolvanen > --- > arch/arm64/kernel/efi-rt-wrapper.S | 7 ++++++- > 1 file changed, 6 insertions(+), 1 deletion(-) > > diff --git a/arch/arm64/kernel/efi-rt-wrapper.S b/arch/arm64/kernel/efi-rt-wrapper.S > index 3fc71106cb2b..945744f16086 100644 > --- a/arch/arm64/kernel/efi-rt-wrapper.S > +++ b/arch/arm64/kernel/efi-rt-wrapper.S > @@ -34,5 +34,10 @@ ENTRY(__efi_rt_asm_wrapper) > ldp x29, x30, [sp], #32 > b.ne 0f > ret > -0: b efi_handle_corrupted_x18 // tail call > +0: > +#ifdef CONFIG_SHADOW_CALL_STACK > + /* Restore x18 before returning to instrumented code. */ > + mov x18, x2 > +#endif > + b efi_handle_corrupted_x18 // tail call > ENDPROC(__efi_rt_asm_wrapper) > -- > 2.23.0.866.gb869b98d4c-goog >