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=-10.0 required=3.0 tests=DKIMWL_WL_HIGH,DKIM_SIGNED, DKIM_VALID,HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_PATCH,MAILING_LIST_MULTI, SIGNED_OFF_BY,SPF_HELO_NONE,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 6057BC433DF for ; Tue, 23 Jun 2020 21:34:52 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 39FEA20707 for ; Tue, 23 Jun 2020 21:34:52 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1592948092; bh=5ZAVH9SdfmQQhgo3sX7+S/z1QXYvRSBynU1C+2z0xYg=; h=From:To:Cc:Subject:Date:In-Reply-To:References:List-ID:From; b=h9TfDWvtVDrm1yz9znEngb86uHNZIiJkreK7O+ufKCNhKPDS1H0wZw6vKjsPX3b6G teH0GQkBxBGAnruH93oiAM8HMDIkdqvcopRPkOXjTUHJCZwplQZ34nzCWjhwx8fJUL 2LSyCFfIIdH75K1PJgU4Km4kWr1ST1XSSGNR1yiU= Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S2388830AbgFWUKp (ORCPT ); Tue, 23 Jun 2020 16:10:45 -0400 Received: from mail.kernel.org ([198.145.29.99]:50976 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S2388757AbgFWUJs (ORCPT ); Tue, 23 Jun 2020 16:09:48 -0400 Received: from localhost (83-86-89-107.cable.dynamic.v4.ziggo.nl [83.86.89.107]) (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 4277520DD4; Tue, 23 Jun 2020 20:09:47 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1592942987; bh=5ZAVH9SdfmQQhgo3sX7+S/z1QXYvRSBynU1C+2z0xYg=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=LO3mEKgmOhBA+/EDt66Z5WuHjFql5s6tJB6w0rMrkQtQtIf/Eek3DTBgxmSNuOAVv BiWmnqmXjC7rIa2YM+22FfRIzYdVTcIQ5h1MWFwbSpYvUPCHto/dywEq0X3SGq/ve7 2tqvH/SLIt0RVOtTBYB2jdPnXUPZynjRbJh69pVE= From: Greg Kroah-Hartman To: linux-kernel@vger.kernel.org Cc: Greg Kroah-Hartman , stable@vger.kernel.org, Nicholas Piggin , Michael Ellerman , Sasha Levin Subject: [PATCH 5.7 215/477] powerpc/64s/exception: Fix machine check no-loss idle wakeup Date: Tue, 23 Jun 2020 21:53:32 +0200 Message-Id: <20200623195417.748191922@linuxfoundation.org> X-Mailer: git-send-email 2.27.0 In-Reply-To: <20200623195407.572062007@linuxfoundation.org> References: <20200623195407.572062007@linuxfoundation.org> User-Agent: quilt/0.66 MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org From: Nicholas Piggin [ Upstream commit 8a5054d8cbbe03c68dcb0957c291c942132e4101 ] The architecture allows for machine check exceptions to cause idle wakeups which resume at the 0x200 address which has to return via the idle wakeup code, but the early machine check handler is run first. The case of a no state-loss sleep is broken because the early handler uses non-volatile register r1 , which is needed for the wakeup protocol, but it is not restored. Fix this by loading r1 from the MCE exception frame before returning to the idle wakeup code. Also update the comment which has become stale since the idle rewrite in C. This crash was found and fix confirmed with a machine check injection test in qemu powernv model (which is not upstream in qemu yet). Fixes: 10d91611f426d ("powerpc/64s: Reimplement book3s idle code in C") Signed-off-by: Nicholas Piggin Signed-off-by: Michael Ellerman Link: https://lore.kernel.org/r/20200508043408.886394-2-npiggin@gmail.com Signed-off-by: Sasha Levin --- arch/powerpc/kernel/exceptions-64s.S | 14 ++++++++------ 1 file changed, 8 insertions(+), 6 deletions(-) diff --git a/arch/powerpc/kernel/exceptions-64s.S b/arch/powerpc/kernel/exceptions-64s.S index ebeebab74b564..463372046169a 100644 --- a/arch/powerpc/kernel/exceptions-64s.S +++ b/arch/powerpc/kernel/exceptions-64s.S @@ -1225,17 +1225,19 @@ EXC_COMMON_BEGIN(machine_check_idle_common) bl machine_check_queue_event /* - * We have not used any non-volatile GPRs here, and as a rule - * most exception code including machine check does not. - * Therefore PACA_NAPSTATELOST does not need to be set. Idle - * wakeup will restore volatile registers. + * GPR-loss wakeups are relatively straightforward, because the + * idle sleep code has saved all non-volatile registers on its + * own stack, and r1 in PACAR1. * - * Load the original SRR1 into r3 for pnv_powersave_wakeup_mce. + * For no-loss wakeups the r1 and lr registers used by the + * early machine check handler have to be restored first. r2 is + * the kernel TOC, so no need to restore it. * * Then decrement MCE nesting after finishing with the stack. */ ld r3,_MSR(r1) ld r4,_LINK(r1) + ld r1,GPR1(r1) lhz r11,PACA_IN_MCE(r13) subi r11,r11,1 @@ -1244,7 +1246,7 @@ EXC_COMMON_BEGIN(machine_check_idle_common) mtlr r4 rlwinm r10,r3,47-31,30,31 cmpwi cr1,r10,2 - bltlr cr1 /* no state loss, return to idle caller */ + bltlr cr1 /* no state loss, return to idle caller with r3=SRR1 */ b idle_return_gpr_loss #endif -- 2.25.1