From nobody Sun Feb 8 23:25:40 2026 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 vger.kernel.org (vger.kernel.org [23.128.96.18]) by smtp.lore.kernel.org (Postfix) with ESMTP id ECCDBC7619A for ; Mon, 27 Mar 2023 08:27:10 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S233381AbjC0I1I (ORCPT ); Mon, 27 Mar 2023 04:27:08 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:33316 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S233115AbjC0I0W (ORCPT ); Mon, 27 Mar 2023 04:26:22 -0400 Received: from mga04.intel.com (mga04.intel.com [192.55.52.120]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 2F83E5FC3; Mon, 27 Mar 2023 01:24:52 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=intel.com; i=@intel.com; q=dns/txt; s=Intel; t=1679905492; x=1711441492; h=from:to:cc:subject:date:message-id:in-reply-to: references:mime-version:content-transfer-encoding; bh=qlKMvNMl6phwDM/NFmlFjCkIxGABaABfFRVavP867bI=; b=NEserNeaek6yzaixPJBN4iyfZ8SxQl4y3g9koSN3zMM7T6hpKzGq7t9S xaOhLvE730k/NDbglyFqkXbMrOU8sMNmBKYbnglKrj6EJcNY3YFbTsVuV 5f5agu6r9eJLTHhkigND+//z14gV6i/KTTf2Ssd0nd7aSfGSTrOaxMbPH jvEllAGHG3vqW2XxogesV4HsCA4RmOV/PlRsnsK2mQmKtnZysYpbTjvH2 25twTTMwOIIBEV0MsHiJ+cL/ozOq3cfgU3vGW3HkPW4V9zBbIUS/31YXa 8hjpiA3sZ+EwUeAXjAkSZCgRvBQRzb+XhC823M9p49eH17Wq3V+Nzub3T A==; X-IronPort-AV: E=McAfee;i="6600,9927,10661"; a="338930418" X-IronPort-AV: E=Sophos;i="5.98,294,1673942400"; d="scan'208";a="338930418" Received: from orsmga008.jf.intel.com ([10.7.209.65]) by fmsmga104.fm.intel.com with ESMTP/TLS/ECDHE-RSA-AES256-GCM-SHA384; 27 Mar 2023 01:24:42 -0700 X-ExtLoop1: 1 X-IronPort-AV: E=McAfee;i="6600,9927,10661"; a="713787159" X-IronPort-AV: E=Sophos;i="5.98,294,1673942400"; d="scan'208";a="713787159" Received: from unknown (HELO fred..) ([172.25.112.68]) by orsmga008.jf.intel.com with ESMTP; 27 Mar 2023 01:24:41 -0700 From: Xin Li To: linux-kernel@vger.kernel.org, x86@kernel.org, kvm@vger.kernel.org Cc: tglx@linutronix.de, mingo@redhat.com, bp@alien8.de, dave.hansen@linux.intel.com, hpa@zytor.com, peterz@infradead.org, andrew.cooper3@citrix.com, seanjc@google.com, pbonzini@redhat.com, ravi.v.shankar@intel.com, jiangshanlai@gmail.com, shan.kang@intel.com Subject: [PATCH v6 31/33] x86/fred: BUG() when ERETU with %rsp not equal to that when the ring 3 event was just delivered Date: Mon, 27 Mar 2023 00:58:36 -0700 Message-Id: <20230327075838.5403-32-xin3.li@intel.com> X-Mailer: git-send-email 2.34.1 In-Reply-To: <20230327075838.5403-1-xin3.li@intel.com> References: <20230327075838.5403-1-xin3.li@intel.com> MIME-Version: 1.0 Content-Transfer-Encoding: quoted-printable Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Type: text/plain; charset="utf-8" A FRED stack frame generated by a ring 3 event should never be messed up, a= nd the first thing we must make sure is that at the time an ERETU instruction = is executed, %rsp must have the same address as that when the user level event was just delivered. However we don't want to bother the normal code path of ERETU because it's = on the hotest code path, a good choice is to do this check when ERETU faults. Suggested-by: H. Peter Anvin (Intel) Tested-by: Shan Kang Signed-off-by: Xin Li --- arch/x86/mm/extable.c | 8 ++++++++ 1 file changed, 8 insertions(+) diff --git a/arch/x86/mm/extable.c b/arch/x86/mm/extable.c index a5d75b27a993..bf8005558935 100644 --- a/arch/x86/mm/extable.c +++ b/arch/x86/mm/extable.c @@ -204,6 +204,14 @@ static bool ex_handler_eretu(const struct exception_ta= ble_entry *fixup, unsigned short ss =3D uregs->ss; unsigned short cs =3D uregs->cs; =20 + /* + * A FRED stack frame generated by a ring 3 event should never be + * messed up, and the first thing we must make sure is that at the + * time an ERETU instruction is executed, %rsp must have the same + * address as that when the user level event was just delivered. + */ + BUG_ON(uregs !=3D current->thread_info.user_pt_regs); + /* * Move the NMI bit from the invalid stack frame, which caused ERETU * to fault, to the fault handler's stack frame, thus to unblock NMI --=20 2.34.1