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=-2.8 required=3.0 tests=HEADER_FROM_DIFFERENT_DOMAINS, MAILING_LIST_MULTI,SPF_PASS,URIBL_BLOCKED,USER_AGENT_GIT 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 6BB1DC3279B for ; Mon, 2 Jul 2018 11:06:36 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 2C50925CC9 for ; Mon, 2 Jul 2018 11:06:36 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org 2C50925CC9 Authentication-Results: mail.kernel.org; dmarc=none (p=none dis=none) header.from=arm.com Authentication-Results: mail.kernel.org; spf=none smtp.mailfrom=linux-kernel-owner@vger.kernel.org Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1030460AbeGBLFI (ORCPT ); Mon, 2 Jul 2018 07:05:08 -0400 Received: from foss.arm.com ([217.140.101.70]:57584 "EHLO foss.arm.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1030373AbeGBLE4 (ORCPT ); Mon, 2 Jul 2018 07:04:56 -0400 Received: from usa-sjc-imap-foss1.foss.arm.com (unknown [10.72.51.249]) by usa-sjc-mx-foss1.foss.arm.com (Postfix) with ESMTP id B58F61682; Mon, 2 Jul 2018 04:04:55 -0700 (PDT) Received: from lakrids.cambridge.arm.com (usa-sjc-imap-foss1.foss.arm.com [10.72.51.249]) by usa-sjc-imap-foss1.foss.arm.com (Postfix) with ESMTPA id A512C3F5BA; Mon, 2 Jul 2018 04:04:53 -0700 (PDT) From: Mark Rutland To: linux-arm-kernel@lists.infradead.org, will.deacon@arm.com Cc: linux-kernel@vger.kernel.org, catalin.marinas@arm.com, dave.martin@arm.com, hch@infradead.org, james.morse@arm.com, linux@dominikbrodowski.net, linux-fsdevel@vger.kernel.org, marc.zyngier@arm.com, mark.rutland@arm.com, viro@zeniv.linux.org.uk Subject: [PATCHv4 12/19] arm64: zero GPRs upon entry from EL0 Date: Mon, 2 Jul 2018 12:04:08 +0100 Message-Id: <20180702110415.10465-13-mark.rutland@arm.com> X-Mailer: git-send-email 2.11.0 In-Reply-To: <20180702110415.10465-1-mark.rutland@arm.com> References: <20180702110415.10465-1-mark.rutland@arm.com> Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org We can zero GPRs x0 - x29 upon entry from EL0 to make it harder for userspace to control values consumed by speculative gadgets. We don't blat x30, since this is stashed much later, and we'll blat it before invoking C code. Signed-off-by: Mark Rutland Acked-by: Catalin Marinas Cc: Will Deacon --- arch/arm64/kernel/entry.S | 8 +++++++- 1 file changed, 7 insertions(+), 1 deletion(-) diff --git a/arch/arm64/kernel/entry.S b/arch/arm64/kernel/entry.S index 728bc7cc5bbb..6b7789d72064 100644 --- a/arch/arm64/kernel/entry.S +++ b/arch/arm64/kernel/entry.S @@ -53,6 +53,12 @@ #endif .endm + .macro clear_gp_regs + .irp n,0,1,2,3,4,5,6,7,8,9,10,11,12,13,14,15,16,17,18,19,20,21,22,23,24,25,26,27,28,29 + mov x\n, xzr + .endr + .endm + /* * Bad Abort numbers *----------------- @@ -169,6 +175,7 @@ skip_apply_ssbd\@: stp x28, x29, [sp, #16 * 14] .if \el == 0 + clear_gp_regs mrs x21, sp_el0 ldr_this_cpu tsk, __entry_task, x20 // Ensure MDSCR_EL1.SS is clear, ldr x19, [tsk, #TSK_TI_FLAGS] // since we can unmask debug @@ -176,7 +183,6 @@ skip_apply_ssbd\@: apply_ssbd 1, x22, x23 - mov x29, xzr // fp pointed to user-space .else add x21, sp, #S_FRAME_SIZE get_thread_info tsk -- 2.11.0