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=-8.2 required=3.0 tests=HEADER_FROM_DIFFERENT_DOMAINS, INCLUDES_PATCH,MAILING_LIST_MULTI,SIGNED_OFF_BY,SPF_HELO_NONE,SPF_PASS, URIBL_BLOCKED,USER_AGENT_SANE_1 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 47393C433DF for ; Tue, 9 Jun 2020 00:54:36 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 2292420760 for ; Tue, 9 Jun 2020 00:54:36 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S2387653AbgFIAy1 (ORCPT ); Mon, 8 Jun 2020 20:54:27 -0400 Received: from mga02.intel.com ([134.134.136.20]:5268 "EHLO mga02.intel.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726904AbgFIAyV (ORCPT ); Mon, 8 Jun 2020 20:54:21 -0400 IronPort-SDR: 2iT1VAJ7QKJIg62srJZF90Jzt/+4IHLpwDnoRzMblwnpF1b6F6+olekk7pQFRzOQc/XVhMuiTs WBXQH23jBnrQ== X-Amp-Result: SKIPPED(no attachment in message) X-Amp-File-Uploaded: False Received: from fmsmga008.fm.intel.com ([10.253.24.58]) by orsmga101.jf.intel.com with ESMTP/TLS/ECDHE-RSA-AES256-GCM-SHA384; 08 Jun 2020 17:54:19 -0700 IronPort-SDR: IE0OzXBrF8K8Gg9X7tlQNcvpRZbS8aIPXNwXPzZRhn9ehVNaJ/+ItkfaFNGQRCNtKhnEsQ+XR6 pvP+RHfqp/kw== X-ExtLoop1: 1 X-IronPort-AV: E=Sophos;i="5.73,490,1583222400"; d="scan'208";a="259970287" Received: from ranerica-svr.sc.intel.com ([172.25.110.23]) by fmsmga008.fm.intel.com with ESMTP; 08 Jun 2020 17:54:19 -0700 Date: Mon, 8 Jun 2020 17:54:34 -0700 From: Ricardo Neri To: Brendan Shanks Cc: linux-kernel@vger.kernel.org, tglx@linutronix.de, mingo@redhat.com, bp@alien8.de, hpa@zytor.com, x86@kernel.org, ebiederm@xmission.com, andi@notmuch.email, Babu.Moger@amd.com Subject: Re: [PATCH v3] x86/umip: Add emulation/spoofing for SLDT and STR instructions Message-ID: <20200609005434.GA26427@ranerica-svr.sc.intel.com> References: <20200608224424.7259-1-bshanks@codeweavers.com> <20200609003812.GA26268@ranerica-svr.sc.intel.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20200609003812.GA26268@ranerica-svr.sc.intel.com> User-Agent: Mutt/1.9.4 (2018-02-28) Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Mon, Jun 08, 2020 at 05:38:12PM -0700, Ricardo Neri wrote: > On Mon, Jun 08, 2020 at 03:44:24PM -0700, Brendan Shanks wrote: > > Add emulation/spoofing of SLDT and STR for both 32- and 64-bit > > processes. > > > > Wine users have found a small number of Windows apps using SLDT that > > were crashing when run on UMIP-enabled systems. > > > > Reported-by: Andreas Rammhold > > Originally-by: Ricardo Neri > > Signed-off-by: Brendan Shanks > > --- > > > > v3: Use (GDT_ENTRY_TSS * 8) for task register selector instead of > > harcoding 0x40. > > > > arch/x86/kernel/umip.c | 32 +++++++++++++++++++++++--------- > > 1 file changed, 23 insertions(+), 9 deletions(-) > > > > diff --git a/arch/x86/kernel/umip.c b/arch/x86/kernel/umip.c > > index 8d5cbe1bbb3b..166c579b0273 100644 > > --- a/arch/x86/kernel/umip.c > > +++ b/arch/x86/kernel/umip.c > > @@ -244,16 +244,35 @@ static int emulate_umip_insn(struct insn *insn, int umip_inst, > > *data_size += UMIP_GDT_IDT_LIMIT_SIZE; > > memcpy(data, &dummy_limit, UMIP_GDT_IDT_LIMIT_SIZE); > > > > - } else if (umip_inst == UMIP_INST_SMSW) { > > - unsigned long dummy_value = CR0_STATE; > > + } else if (umip_inst == UMIP_INST_SMSW || umip_inst == UMIP_INST_SLDT || > > + umip_inst == UMIP_INST_STR) { > > + unsigned long dummy_value; > > + > > + if (umip_inst == UMIP_INST_SMSW) > > + dummy_value = CR0_STATE; > > + else if (umip_inst == UMIP_INST_STR) > > + dummy_value = GDT_ENTRY_TSS * 8; > > + else if (umip_inst == UMIP_INST_SLDT) > > + { > > This brace should go in the previous line. Also, if you use braces in > the last part of the conditional you should probably use them in the > previous ones. I guess in this case it woudln't improve readability. > Instead, you can probably have a switch instead of the three ifs. That > probably does improve readability and solves the dilemma of needing to > put braces in all the one-line conditionals. > > BTW, you should also delete the comment at the top of the file saying > that str and sldt will not be emulated: > > diff --git a/arch/x86/kernel/umip.c b/arch/x86/kernel/umip.c > index 166c579b0273..0984a55eb8c0 100644 > --- a/arch/x86/kernel/umip.c > +++ b/arch/x86/kernel/umip.c > @@ -45,9 +45,6 @@ > * value that, lies close to the top of the kernel memory. The limit for the GDT > * and the IDT are set to zero. > * > - * Given that SLDT and STR are not commonly used in programs that run on WineHQ > - * or DOSEMU2, they are not emulated. > - * > * The instruction smsw is emulated to return the value that the register CR0 > * has at boot time as set in the head_32. ... And also explain that the emulated values for str and sldt are the simply the values that Linux assigns programatically. Thanks and BR, Ricardo