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=-10.1 required=3.0 tests=DKIMWL_WL_HIGH,DKIM_SIGNED, DKIM_VALID,DKIM_VALID_AU,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 A0D06C433E0 for ; Thu, 18 Jun 2020 02:18:09 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 7931C2088E for ; Thu, 18 Jun 2020 02:18:09 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1592446689; bh=d8hWKR8nu0SzVC4KJO15bRIP1AlgJ0tDnm9EpB/vIhU=; h=From:To:Cc:Subject:Date:In-Reply-To:References:List-ID:From; b=dZVhooI04DkMMQMS6f6JLqS2ggn8/FSBx3Ti0zl9UF6HBK7JkT7k+LZyd4P+BDTP6 1eGW/WnKwhdlj+By3lFNITwZI8kGPpxr7vzgpUXYD1vUJ8r12KW6ivj3HKfhEFfAxq WfWkN2jA52xsWyPpALHvy2+ey/gpSbTZeUSwZLYA= Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1730494AbgFRCSF (ORCPT ); Wed, 17 Jun 2020 22:18:05 -0400 Received: from mail.kernel.org ([198.145.29.99]:51668 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1730208AbgFRBTv (ORCPT ); Wed, 17 Jun 2020 21:19:51 -0400 Received: from sasha-vm.mshome.net (c-73-47-72-35.hsd1.nh.comcast.net [73.47.72.35]) (using TLSv1.2 with cipher ECDHE-RSA-AES128-GCM-SHA256 (128/128 bits)) (No client certificate requested) by mail.kernel.org (Postfix) with ESMTPSA id 6B73A21D80; Thu, 18 Jun 2020 01:19:48 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1592443189; bh=d8hWKR8nu0SzVC4KJO15bRIP1AlgJ0tDnm9EpB/vIhU=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=VUh3jU1aFOfflb6/F/rJPr2BP7DTxO9T91QTtgzoG3UMJlwqKDGQopNXck/zTr0ag BBhjrMFfWxJTvyRWeCR9hlSRq2qRkZFuXPeJacAigyvB4zkdJQf5/s5kd7qA3cLx9F 8Q1ILlWnZbUzepy8q5UN/5peA1pYzW8Khw4/PfQY= From: Sasha Levin To: linux-kernel@vger.kernel.org, stable@vger.kernel.org Cc: Nicholas Piggin , Michael Ellerman , Sasha Levin , linuxppc-dev@lists.ozlabs.org Subject: [PATCH AUTOSEL 5.4 150/266] powerpc/64s/exception: Fix machine check no-loss idle wakeup Date: Wed, 17 Jun 2020 21:14:35 -0400 Message-Id: <20200618011631.604574-150-sashal@kernel.org> X-Mailer: git-send-email 2.25.1 In-Reply-To: <20200618011631.604574-1-sashal@kernel.org> References: <20200618011631.604574-1-sashal@kernel.org> MIME-Version: 1.0 X-stable: review X-Patchwork-Hint: Ignore 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 d0018dd17e0a..70ac8a6ba0c1 100644 --- a/arch/powerpc/kernel/exceptions-64s.S +++ b/arch/powerpc/kernel/exceptions-64s.S @@ -1090,17 +1090,19 @@ 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 @@ -1109,7 +1111,7 @@ 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