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=-8.5 required=3.0 tests=DKIMWL_WL_HIGH,DKIM_SIGNED, DKIM_VALID,INCLUDES_PATCH,MAILING_LIST_MULTI,SIGNED_OFF_BY,SPF_HELO_NONE, SPF_PASS,USER_AGENT_SANE_1 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 B0611C33CB3 for ; Thu, 16 Jan 2020 18:33:05 +0000 (UTC) Received: from bombadil.infradead.org (bombadil.infradead.org [198.137.202.133]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by mail.kernel.org (Postfix) with ESMTPS id 8BF9A206D7 for ; Thu, 16 Jan 2020 18:33:05 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (2048-bit key) header.d=lists.infradead.org header.i=@lists.infradead.org header.b="ZdvlUzRa"; dkim=fail reason="signature verification failed" (1024-bit key) header.d=kernel.org header.i=@kernel.org header.b="zlHbDbVJ" DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org 8BF9A206D7 Authentication-Results: mail.kernel.org; dmarc=fail (p=none dis=none) header.from=kernel.org Authentication-Results: mail.kernel.org; spf=none smtp.mailfrom=linux-arm-kernel-bounces+infradead-linux-arm-kernel=archiver.kernel.org@lists.infradead.org DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=lists.infradead.org; s=bombadil.20170209; h=Sender: Content-Transfer-Encoding:Content-Type:Cc:List-Subscribe:List-Help:List-Post: List-Archive:List-Unsubscribe:List-Id:In-Reply-To:MIME-Version:References: Message-ID:Subject:To:From:Date:Reply-To:Content-ID:Content-Description: Resent-Date:Resent-From:Resent-Sender:Resent-To:Resent-Cc:Resent-Message-ID: List-Owner; bh=gA7q8oWAWcFVXcSEpZuR2shYusUsHAdCTYgtNgdhTuo=; b=ZdvlUzRazBpE6P MY3Y21cvvMuY99nGLQO0TfH5EJiDXoGyY38suzNcu3YllBCLYDJ/F2jpYU8kuXzVtgBscBfuI0nsw I74zha5+OKlePfqN6pKP1Q6hM3JENwEP0Xl2GdfybJlkBusLdt7YkhwzAHt/gqrK1RM2df82SCxoP K1RAj9WjoJfu04ePslpO6iGbmDaE3AcV7gjn3d8d8Q+hvURPSQxIrnIe8JnCJAPG0pai2xZHR0SXz I3dEOPWtvAK4ghWfOL0dylYgXDls0Ke28b7UO8NwWS1H1+Z+HiBl+XyIZJlAzppuXKNAuo9jJqhq2 BZvAcx+9Yv2x8Fv66cjQ==; Received: from localhost ([127.0.0.1] helo=bombadil.infradead.org) by bombadil.infradead.org with esmtp (Exim 4.92.3 #3 (Red Hat Linux)) id 1is9wu-000231-1a; Thu, 16 Jan 2020 18:32:56 +0000 Received: from mail.kernel.org ([198.145.29.99]) by bombadil.infradead.org with esmtps (Exim 4.92.3 #3 (Red Hat Linux)) id 1is9CT-0004np-VE for linux-arm-kernel@lists.infradead.org; Thu, 16 Jan 2020 17:45:01 +0000 Received: from willie-the-truck (236.31.169.217.in-addr.arpa [217.169.31.236]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by mail.kernel.org (Postfix) with ESMTPSA id D46112477B; Thu, 16 Jan 2020 17:44:54 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1579196697; bh=eZc1L4+pca2HQRZ4NlFHXHq40yJapRdOmzlFzQ/cknQ=; h=Date:From:To:Cc:Subject:References:In-Reply-To:From; b=zlHbDbVJTAEzMxf/SUtdxJAXgWWsPwuJLkj5y/dsFpdWk6r25yTkB4U8bYfo9zX64 84fLlEQVbP4jGLbiOgOA8O5xtVXhKMTROUWezOITnG+sEvonw9zZ2G1XCxQxKBbcNo IIkiMjs9fllhsIEfoPhk17Sc1+ru8i2vFwMMaDwY= Date: Thu, 16 Jan 2020 17:44:51 +0000 From: Will Deacon To: Sami Tolvanen Subject: Re: [PATCH v6 11/15] arm64: efi: restore x18 if it was corrupted Message-ID: <20200116174450.GD21396@willie-the-truck> References: <20191018161033.261971-1-samitolvanen@google.com> <20191206221351.38241-1-samitolvanen@google.com> <20191206221351.38241-12-samitolvanen@google.com> MIME-Version: 1.0 Content-Disposition: inline In-Reply-To: <20191206221351.38241-12-samitolvanen@google.com> User-Agent: Mutt/1.10.1 (2018-07-13) X-CRM114-Version: 20100106-BlameMichelson ( TRE 0.8.0 (BSD) ) MR-646709E3 X-CRM114-CacheID: sfid-20200116_094458_032880_A2364D8C X-CRM114-Status: GOOD ( 16.08 ) X-BeenThere: linux-arm-kernel@lists.infradead.org X-Mailman-Version: 2.1.29 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Cc: Mark Rutland , Kees Cook , Ard Biesheuvel , Masahiro Yamada , Catalin Marinas , Jann Horn , Nick Desaulniers , linux-kernel@vger.kernel.org, Steven Rostedt , Miguel Ojeda , clang-built-linux@googlegroups.com, Masami Hiramatsu , Marc Zyngier , kernel-hardening@lists.openwall.com, Laura Abbott , Dave Martin , linux-arm-kernel@lists.infradead.org Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Sender: "linux-arm-kernel" Errors-To: linux-arm-kernel-bounces+infradead-linux-arm-kernel=archiver.kernel.org@lists.infradead.org On Fri, Dec 06, 2019 at 02:13:47PM -0800, Sami Tolvanen wrote: > If we detect a corrupted x18 and SCS is enabled, restore the register > before jumping back to instrumented code. This is safe, because the > wrapper is called with preemption disabled and a separate shadow stack > is used for interrupt handling. > > Signed-off-by: Sami Tolvanen > Reviewed-by: Kees Cook > --- > arch/arm64/kernel/efi-rt-wrapper.S | 11 ++++++++++- > 1 file changed, 10 insertions(+), 1 deletion(-) > > diff --git a/arch/arm64/kernel/efi-rt-wrapper.S b/arch/arm64/kernel/efi-rt-wrapper.S > index 3fc71106cb2b..62f0260f5c17 100644 > --- a/arch/arm64/kernel/efi-rt-wrapper.S > +++ b/arch/arm64/kernel/efi-rt-wrapper.S > @@ -34,5 +34,14 @@ 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. This is > + * safe because the wrapper is called with preemption disabled and > + * a separate shadow stack is used for interrupts. > + */ > + mov x18, x2 > +#endif Why not restore it regardless of CONFIG_SHADOW_CALL_STACK? Will _______________________________________________ linux-arm-kernel mailing list linux-arm-kernel@lists.infradead.org http://lists.infradead.org/mailman/listinfo/linux-arm-kernel