From patchwork Tue May 28 06:38:36 2024 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 8bit X-Patchwork-Submitter: Tony W Wang-oc X-Patchwork-Id: 13676195 Received: from mx2.zhaoxin.com (mx2.zhaoxin.com [203.110.167.99]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id CD05D1BDD3 for ; Tue, 28 May 2024 06:54:58 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=203.110.167.99 ARC-Seal: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1716879303; cv=none; b=gTND5TnRPOvqnhfnNo7K4CglhnsVu+dpvbtf3b3qzg/AchbKnUUEeFW4u90jiI21CiBg4OnopgcEoQhOmZqNdheKSuj+GFIegqpSLLYsfx8wKq4rbAfawQgFnrXomFr6vom2VD6aaa28eHxXHuXLXsLa43WaPu7o1DoGHo9iTKI= ARC-Message-Signature: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1716879303; c=relaxed/simple; bh=k/kiyNBZ/CQQZm9441hQ2gzjm+HeVypZQxq7MFeGzuU=; h=From:To:CC:Subject:Date:Message-ID:MIME-Version:Content-Type; b=OSdyrFL/03CzgPVM0TzKqOu3OjT2SneXIIwpoOlcpOIucsjIjVWNjF7ljQ0kUX5Qk/NuxDhUId29Lmdx0lUywTBjv6PMRXE2L5QQtBwc1Z5Ycc3F91roJkcFEMZxYlHy4F17bt4nEd3JHKqgg1r6FsFIxn+MJezdGP8gjI9eOAo= ARC-Authentication-Results: i=1; smtp.subspace.kernel.org; dmarc=none (p=none dis=none) header.from=zhaoxin.com; spf=pass smtp.mailfrom=zhaoxin.com; arc=none smtp.client-ip=203.110.167.99 Authentication-Results: smtp.subspace.kernel.org; dmarc=none (p=none dis=none) header.from=zhaoxin.com Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=zhaoxin.com X-ASG-Debug-ID: 1716878322-1eb14e15750e370001-PleebU Received: from ZXSHMBX3.zhaoxin.com (ZXSHMBX3.zhaoxin.com [10.28.252.165]) by mx2.zhaoxin.com with ESMTP id gd8N2tgmRDCGMwi7 (version=TLSv1.2 cipher=ECDHE-RSA-AES128-GCM-SHA256 bits=128 verify=NO); Tue, 28 May 2024 14:38:42 +0800 (CST) X-Barracuda-Envelope-From: TonyWWang-oc@zhaoxin.com X-Barracuda-RBL-Trusted-Forwarder: 10.28.252.165 Received: from ZXBJMBX03.zhaoxin.com (10.29.252.7) by ZXSHMBX3.zhaoxin.com (10.28.252.165) with Microsoft SMTP Server (version=TLS1_2, cipher=TLS_ECDHE_RSA_WITH_AES_128_GCM_SHA256) id 15.1.2507.27; Tue, 28 May 2024 14:38:41 +0800 Received: from localhost.localdomain (10.32.65.162) by ZXBJMBX03.zhaoxin.com (10.29.252.7) with Microsoft SMTP Server (version=TLS1_2, cipher=TLS_ECDHE_RSA_WITH_AES_128_GCM_SHA256) id 15.1.2507.27; Tue, 28 May 2024 14:38:37 +0800 X-Barracuda-RBL-Trusted-Forwarder: 10.28.252.165 From: Tony W Wang-oc X-Barracuda-RBL-Trusted-Forwarder: 10.29.252.7 To: , , , , , , , , , , , , , , , , , , CC: , , Subject: [PATCH] x86/hpet: Read HPET directly if panic in progress Date: Tue, 28 May 2024 14:38:36 +0800 X-ASG-Orig-Subj: [PATCH] x86/hpet: Read HPET directly if panic in progress Message-ID: <20240528063836.5248-1-TonyWWang-oc@zhaoxin.com> X-Mailer: git-send-email 2.25.1 Precedence: bulk X-Mailing-List: linux-hardening@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 X-ClientProxiedBy: zxbjmbx1.zhaoxin.com (10.29.252.163) To ZXBJMBX03.zhaoxin.com (10.29.252.7) X-Barracuda-Connect: ZXSHMBX3.zhaoxin.com[10.28.252.165] X-Barracuda-Start-Time: 1716878322 X-Barracuda-Encrypted: ECDHE-RSA-AES128-GCM-SHA256 X-Barracuda-URL: https://10.28.252.36:4443/cgi-mod/mark.cgi X-Virus-Scanned: by bsmtpd at zhaoxin.com X-Barracuda-Scan-Msg-Size: 1321 X-Barracuda-BRTS-Status: 1 X-Barracuda-Bayes: INNOCENT GLOBAL 0.0000 1.0000 -2.0210 X-Barracuda-Spam-Score: -2.02 X-Barracuda-Spam-Status: No, SCORE=-2.02 using global scores of TAG_LEVEL=1000.0 QUARANTINE_LEVEL=1000.0 KILL_LEVEL=9.0 tests= X-Barracuda-Spam-Report: Code version 3.2, rules version 3.2.3.125447 Rule breakdown below pts rule name description ---- ---------------------- -------------------------------------------------- When the clocksource of the system is HPET，a CPU executing read_hpet might be interrupted by exceptions to executing the panic，this may lead to read_hpet dead loops: CPU x CPU x ---- ---- read_hpet() arch_spin_trylock(&hpet.lock) [CPU x got the hpet.lock] #MCE happened do_machine_check() mce_panic() panic() kmsg_dump() pstore_dump() pstore_record_init() ktime_get_real_fast_ns() read_hpet() [dead loops] To avoid this dead loops, read HPET directly if panic in progress. Signed-off-by: Tony W Wang-oc --- arch/x86/kernel/hpet.c | 6 ++++++ 1 file changed, 6 insertions(+) diff --git a/arch/x86/kernel/hpet.c b/arch/x86/kernel/hpet.c index c96ae8fee95e..ecadd0698d6a 100644 --- a/arch/x86/kernel/hpet.c +++ b/arch/x86/kernel/hpet.c @@ -804,6 +804,12 @@ static u64 read_hpet(struct clocksource *cs) if (in_nmi()) return (u64)hpet_readl(HPET_COUNTER); + /* + * Read HPET directly if panic in progress. + */ + if (unlikely(atomic_read(&panic_cpu) != PANIC_CPU_INVALID)) + return (u64)hpet_readl(HPET_COUNTER); + /* * Read the current state of the lock and HPET value atomically. */