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 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 smtp.lore.kernel.org (Postfix) with ESMTPS id CB1DCC43458 for ; Fri, 10 Jul 2026 03:01:10 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=lists.infradead.org; s=bombadil.20210309; h=Sender:Cc:List-Subscribe: List-Help:List-Post:List-Archive:List-Unsubscribe:List-Id: Content-Transfer-Encoding:Content-Type:In-Reply-To:From:References:To:Subject :MIME-Version:Date:Message-ID:Reply-To:Content-ID:Content-Description: Resent-Date:Resent-From:Resent-Sender:Resent-To:Resent-Cc:Resent-Message-ID: List-Owner; bh=+whd98gkPu5jy8XKY6BJyQ2Wp5rZ4pLqUlbmWeYTj1s=; b=hkcCT89riCSemR aRgpa4g7F0Rl99Dks4vW/6In+xVe22o5k5v/Ysk8slxD8oLisC2OuvImD3ki9s8KaJHH+TCDWCUsb 9woFyBsWrfAq4SdegLsmrCp/yqsrq15Z4X9Hs7W8/2oIeyFC/R7i906iE/Ktz2f1mvd0l3CzfxC8u qDfKZTyU0ZPJHvikK8qtOa3JVqVTV0h0SJdo3ZVTx0ql3WTcKQc3QUAR3RbIugGSxR/jpHEoOJ6Ak PQTFs288LqMns7nJCcRkwnRKF9EYLb0z/alDz6SbsT07aqkMo4j76pDo6Nvjm3pVhlM2ArZpvz7nL HsmbautfKoScp8btUXHw==; Received: from localhost ([::1] helo=bombadil.infradead.org) by bombadil.infradead.org with esmtp (Exim 4.99.1 #2 (Red Hat Linux)) id 1wi1Tz-000000040nA-1oWT; Fri, 10 Jul 2026 03:00:55 +0000 Received: from canpmsgout07.his.huawei.com ([113.46.200.222]) by bombadil.infradead.org with esmtps (Exim 4.99.1 #2 (Red Hat Linux)) id 1wi1Tu-000000040mh-3HFh for linux-arm-kernel@lists.infradead.org; Fri, 10 Jul 2026 03:00:53 +0000 dkim-signature: v=1; a=rsa-sha256; d=huawei.com; s=dkim; c=relaxed/relaxed; q=dns/txt; h=From; bh=+whd98gkPu5jy8XKY6BJyQ2Wp5rZ4pLqUlbmWeYTj1s=; b=T+3HsfGEwemMcdh7mpGX/2MY1dyGaGFHiGH9Duu8Zc03LqiYtyEs1QCXLB3teikJFA5B7eHxi YYL9GE680270H7GpvinkBT7wwgluFlv/Nu/Ainauum7PBtawYVMmrznkCmdWf/GnDLSOAq/Jjz9 h20TVm5bBaKgNtCIqgeneOg= Received: from mail.maildlp.com (unknown [172.19.163.200]) by canpmsgout07.his.huawei.com (SkyGuard) with ESMTPS id 4gxGYn5qZxzLlTD; Fri, 10 Jul 2026 10:51:25 +0800 (CST) Received: from dggpemf500011.china.huawei.com (unknown [7.185.36.131]) by mail.maildlp.com (Postfix) with ESMTPS id E2D584055B; Fri, 10 Jul 2026 11:00:40 +0800 (CST) Received: from [10.67.109.254] (10.67.109.254) by dggpemf500011.china.huawei.com (7.185.36.131) with Microsoft SMTP Server (version=TLS1_2, cipher=TLS_ECDHE_RSA_WITH_AES_256_GCM_SHA384) id 15.2.1544.11; Fri, 10 Jul 2026 11:00:40 +0800 Message-ID: <68e740e3-5fa6-4ab7-92f1-3f570fc07801@huawei.com> Date: Fri, 10 Jul 2026 11:00:38 +0800 MIME-Version: 1.0 User-Agent: Mozilla Thunderbird Subject: Re: [RFC PATCH 03/36] arm64: hibernate: mask DAIF before restoring hibernated kernel To: Vladimir Murzin , References: <20260709121333.23507-1-vladimir.murzin@arm.com> <20260709121333.23507-4-vladimir.murzin@arm.com> From: Jinjie Ruan In-Reply-To: <20260709121333.23507-4-vladimir.murzin@arm.com> Content-Type: text/plain; charset="UTF-8" Content-Transfer-Encoding: 7bit X-Originating-IP: [10.67.109.254] X-ClientProxiedBy: kwepems500002.china.huawei.com (7.221.188.17) To dggpemf500011.china.huawei.com (7.185.36.131) X-CRM114-Version: 20100106-BlameMichelson ( TRE 0.9.0 (BSD) ) MR-646709E3 X-CRM114-CacheID: sfid-20260709_200051_476309_9AD2633B X-CRM114-Status: GOOD ( 23.90 ) X-BeenThere: linux-arm-kernel@lists.infradead.org X-Mailman-Version: 2.1.34 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Cc: mark.rutland@arm.com, maz@kernel.org, stable@vger.kernel.org, catalin.marinas@arm.com, will@kernel.org Sender: "linux-arm-kernel" Errors-To: linux-arm-kernel-bounces+linux-arm-kernel=archiver.kernel.org@lists.infradead.org On 7/9/2026 8:13 PM, Vladimir Murzin wrote: > From: Ada Couprie Diaz > > The arm64 hibernate code manages the exception masking in an unsound > way, leading to potential crashes and/or warnings during resume. > > When a hibernation image is saved in `swsusp_arch_suspend()`, all DAIF > exceptions are masked (by virtue of `local_daif_save()`), and the > suspended image is saved assuming that all DAIF exceptions will remain > masked when the image is restored. > > When a hibernation image is resumed by `swsusp_arch_resume()`, only > interrupts are masked (by virtue of `local_irq_save()` in > `resume_target_kernel()`). When pseudo-NMI is enabled the DAIF.IF bits > will be clear, and regardless of pseudo-NMI the DAIF.DA bits will be > clear. > > This means that there are two problems: > > (1) It is possible to take Debug, SError, or pseudo-NMI exceptions > during the resume process. This is unsafe, as during the resume > process both the old ane new kernels will tranisently be in an > inconsistent state, and swsusp_arch_suspend_exit() won't retain > an executable mapping of any exception vectors. > > Any exception taken here will be fatal and silent. > > (2) When re-entering the resumed kernel, some DAIF bits will be clear > unexpectedly. This permits Debug, SError, or pseudo-NMI exceptions > to be taken for a short period while the resumed kernel is not yet > in a consistent state. > > This is detected by CONFIG_ARM64_DEBUG_PRIORITY_MASKING. > > Avoid these issues by masking all DAIF exceptions during resume. > > Cc: stable@vger.kernel.org > Signed-off-by: Ada Couprie Diaz > Signed-off-by: Vladimir Murzin > --- > arch/arm64/kernel/hibernate.c | 13 +++++++++++++ > 1 file changed, 13 insertions(+) > > diff --git a/arch/arm64/kernel/hibernate.c b/arch/arm64/kernel/hibernate.c > index 9717568518ba..d0d9bd91e639 100644 > --- a/arch/arm64/kernel/hibernate.c > +++ b/arch/arm64/kernel/hibernate.c > @@ -405,6 +405,7 @@ int swsusp_arch_suspend(void) > int __nocfi swsusp_arch_resume(void) > { > int rc; > + unsigned long flags; > void *zero_page; > size_t exit_size; > pgd_t *tmp_pg_dir; > @@ -465,9 +466,21 @@ int __nocfi swsusp_arch_resume(void) > if (el2_reset_needed()) > __hyp_set_vectors(el2_vectors); > > + /* > + * It is necessary to mask all DAIF exceptions here as: > + * > + * - The copy of swsusp_arch_suspend_exit() in the hibernation > + * text cannot handle taking any exceptions. > + * > + * - The suspended kernel masked all DAIF exceptions in > + * swsusp_arch_resume(), and expects to be re-entered in the > + * same state : with all DAIF exceptions masked. > + */ > + flags = local_daif_save(); > hibernate_exit(virt_to_phys(tmp_pg_dir), resume_hdr.ttbr1_el1, > resume_hdr.reenter_kernel, restore_pblist, > resume_hdr.__hyp_stub_vectors, virt_to_phys(zero_page)); hibernate_exit() is a noreturn function, the following local_daif_restore() will not be called. > + local_daif_restore(flags); > > return 0; > }