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=-9.8 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,USER_AGENT_GIT autolearn=unavailable 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 5BEFCC35242 for ; Fri, 24 Jan 2020 11:32:15 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 32E2121556 for ; Fri, 24 Jan 2020 11:32:15 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1579865535; bh=e6LrhppPSWmwo4SwTVxa11bvIPM7NUDheCDYZfySAfE=; h=From:To:Cc:Subject:Date:In-Reply-To:References:List-ID:From; b=fwvzVQG8YfifMuPJZbAILRF44oyGaPspmS5lMvlbFyPSywIO9p1+tX7dMlIqLbkPJ cusk2WWOFeltFDvnxI13UN9YB4KCxQdEkI5lAyingoHFCRaTH71gsZ+/3/nJJoycTC k/iQ0rwoarxwiQZ/PUY/iruGXgUaTFyZiQM4jjNc= Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S2404422AbgAXLcO (ORCPT ); Fri, 24 Jan 2020 06:32:14 -0500 Received: from mail.kernel.org ([198.145.29.99]:50880 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S2404379AbgAXLcJ (ORCPT ); Fri, 24 Jan 2020 06:32:09 -0500 Received: from localhost (ip-213-127-102-57.ip.prioritytelecom.net [213.127.102.57]) (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 A0CA720704; Fri, 24 Jan 2020 11:32:07 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1579865528; bh=e6LrhppPSWmwo4SwTVxa11bvIPM7NUDheCDYZfySAfE=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=wZeJSPOtUiJP6FqWhT9aJ3VHlg2Q+W3vfivnmmbhV5Vq43hCtTFGlbinnsiWX6Rpv JQXezkHd87lLLUKEB3vFQ7B7cp7EPCHLsA/Haq1f6Re2m2UjzPZqJhC0xMEJhLVC9d SLg/67Z5XgnN+cteSwyKd5QuoBAGWwox0M2VEbuY= From: Greg Kroah-Hartman To: linux-kernel@vger.kernel.org Cc: Greg Kroah-Hartman , stable@vger.kernel.org, "Aneesh Kumar K.V" , Michael Ellerman , Sasha Levin Subject: [PATCH 4.19 570/639] powerpc/mm/mce: Keep irqs disabled during lockless page table walk Date: Fri, 24 Jan 2020 10:32:20 +0100 Message-Id: <20200124093200.766629221@linuxfoundation.org> X-Mailer: git-send-email 2.25.0 In-Reply-To: <20200124093047.008739095@linuxfoundation.org> References: <20200124093047.008739095@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: Aneesh Kumar K.V [ Upstream commit d9101bfa6adc831bda8836c4d774820553c14942 ] __find_linux_mm_pte() returns a page table entry pointer after walking the page table without holding locks. To make it safe against a THP split and/or collapse, we disable interrupts around the lockless page table walk. However we need to keep interrupts disabled as long as we use the page table entry pointer that is returned. Fix addr_to_pfn() to do that. Fixes: ba41e1e1ccb9 ("powerpc/mce: Hookup derror (load/store) UE errors") Signed-off-by: Aneesh Kumar K.V [mpe: Rearrange code slightly and tweak change log wording] Signed-off-by: Michael Ellerman Link: https://lore.kernel.org/r/20190918145328.28602-1-aneesh.kumar@linux.ibm.com Signed-off-by: Sasha Levin --- arch/powerpc/kernel/mce_power.c | 20 ++++++++++++-------- 1 file changed, 12 insertions(+), 8 deletions(-) diff --git a/arch/powerpc/kernel/mce_power.c b/arch/powerpc/kernel/mce_power.c index 37a110b8e7e17..ecb3750406378 100644 --- a/arch/powerpc/kernel/mce_power.c +++ b/arch/powerpc/kernel/mce_power.c @@ -40,7 +40,7 @@ static unsigned long addr_to_pfn(struct pt_regs *regs, unsigned long addr) { pte_t *ptep; unsigned int shift; - unsigned long flags; + unsigned long pfn, flags; struct mm_struct *mm; if (user_mode(regs)) @@ -50,18 +50,22 @@ static unsigned long addr_to_pfn(struct pt_regs *regs, unsigned long addr) local_irq_save(flags); ptep = __find_linux_pte(mm->pgd, addr, NULL, &shift); - local_irq_restore(flags); - if (!ptep || pte_special(*ptep)) - return ULONG_MAX; + if (!ptep || pte_special(*ptep)) { + pfn = ULONG_MAX; + goto out; + } - if (shift > PAGE_SHIFT) { + if (shift <= PAGE_SHIFT) + pfn = pte_pfn(*ptep); + else { unsigned long rpnmask = (1ul << shift) - PAGE_SIZE; - - return pte_pfn(__pte(pte_val(*ptep) | (addr & rpnmask))); + pfn = pte_pfn(__pte(pte_val(*ptep) | (addr & rpnmask))); } - return pte_pfn(*ptep); +out: + local_irq_restore(flags); + return pfn; } /* flush SLBs and reload */ -- 2.20.1