From patchwork Fri May 1 22:58:31 2020 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 8bit X-Patchwork-Submitter: Andrew Cooper X-Patchwork-Id: 11523405 Return-Path: Received: from mail.kernel.org (pdx-korg-mail-1.web.codeaurora.org [172.30.200.123]) by pdx-korg-patchwork-2.web.codeaurora.org (Postfix) with ESMTP id 78E4E81 for ; Fri, 1 May 2020 23:01:04 +0000 (UTC) Received: from lists.xenproject.org (lists.xenproject.org [192.237.175.120]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by mail.kernel.org (Postfix) with ESMTPS id 54DA6208DB for ; Fri, 1 May 2020 23:01:04 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=fail reason="signature verification failed" (1024-bit key) header.d=citrix.com header.i=@citrix.com header.b="ErI7A2pb" DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org 54DA6208DB Authentication-Results: mail.kernel.org; dmarc=fail (p=none dis=none) header.from=citrix.com Authentication-Results: mail.kernel.org; spf=pass smtp.mailfrom=xen-devel-bounces@lists.xenproject.org Received: from localhost ([127.0.0.1] helo=lists.xenproject.org) by lists.xenproject.org with esmtp (Exim 4.92) (envelope-from ) id 1jUeci-0007xH-PR; Fri, 01 May 2020 22:59:12 +0000 Received: from us1-rack-iad1.inumbo.com ([172.99.69.81]) by lists.xenproject.org with esmtp (Exim 4.92) (envelope-from ) id 1jUech-0007wd-3P for xen-devel@lists.xenproject.org; Fri, 01 May 2020 22:59:11 +0000 X-Inumbo-ID: 58e26510-8bff-11ea-b07b-bc764e2007e4 Received: from esa3.hc3370-68.iphmx.com (unknown [216.71.145.155]) by us1-rack-iad1.inumbo.com (Halon) with ESMTPS id 58e26510-8bff-11ea-b07b-bc764e2007e4; Fri, 01 May 2020 22:59:01 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=simple/simple; d=citrix.com; s=securemail; t=1588373941; h=from:to:cc:subject:date:message-id:in-reply-to: references:mime-version:content-transfer-encoding; bh=Ap0r5eSmJ8rufFjf/AMweZgfzQrJaoB/RQzTcg9JGIc=; b=ErI7A2pbb2ioIashxwuWHNLQAyklofIDa/D2N96acCgo3k+vCBkNV2gK gmAuAy5i5iA+cQnrVzmK88VQ/LTbg75b+zi+1DEK5gVd0h5Aj9ysdA2Zo R8289BthNZdqkpTON6atESa0yYzB1en2ytYN+Xhv7iVQMZrSrcDJ7Zvod Y=; Authentication-Results: esa3.hc3370-68.iphmx.com; dkim=none (message not signed) header.i=none; spf=None smtp.pra=andrew.cooper3@citrix.com; spf=Pass smtp.mailfrom=Andrew.Cooper3@citrix.com; spf=None smtp.helo=postmaster@mail.citrix.com Received-SPF: None (esa3.hc3370-68.iphmx.com: no sender authenticity information available from domain of andrew.cooper3@citrix.com) identity=pra; client-ip=162.221.158.21; receiver=esa3.hc3370-68.iphmx.com; envelope-from="Andrew.Cooper3@citrix.com"; x-sender="andrew.cooper3@citrix.com"; x-conformance=sidf_compatible Received-SPF: Pass (esa3.hc3370-68.iphmx.com: domain of Andrew.Cooper3@citrix.com designates 162.221.158.21 as permitted sender) identity=mailfrom; client-ip=162.221.158.21; receiver=esa3.hc3370-68.iphmx.com; envelope-from="Andrew.Cooper3@citrix.com"; x-sender="Andrew.Cooper3@citrix.com"; x-conformance=sidf_compatible; x-record-type="v=spf1"; x-record-text="v=spf1 ip4:209.167.231.154 ip4:178.63.86.133 ip4:195.66.111.40/30 ip4:85.115.9.32/28 ip4:199.102.83.4 ip4:192.28.146.160 ip4:192.28.146.107 ip4:216.52.6.88 ip4:216.52.6.188 ip4:162.221.158.21 ip4:162.221.156.83 ip4:168.245.78.127 ~all" Received-SPF: None (esa3.hc3370-68.iphmx.com: no sender authenticity information available from domain of postmaster@mail.citrix.com) identity=helo; client-ip=162.221.158.21; receiver=esa3.hc3370-68.iphmx.com; envelope-from="Andrew.Cooper3@citrix.com"; x-sender="postmaster@mail.citrix.com"; x-conformance=sidf_compatible IronPort-SDR: l2SQ2JLuOddSOfsNIBJCTSLhOtnmkBvFgvONzvDTCcY8Vkp/NtCl2khdZ9t2t6JtA7zD4GarrM BqM+kxLU7j90gPA9Mp6887De5bHXiO5NWfRNikGaWTDozSZykal5kSAwGFRXOF2TRn2G8/vW9i psvTC6stvSV5iP+ognHDjvS9c8hUo0/bVTGX/mip9oFyenMUwKfYF0xuGotxrfdCAmi16TcbUO IZ+h13PiXE4v3ZHgGZU4m+eNTts24WDvxeJeeOa5GzXBA0gSoFcgRtRKUSN69nEpr7Ozrc7ZXV m00= X-SBRS: 2.7 X-MesageID: 16584677 X-Ironport-Server: esa3.hc3370-68.iphmx.com X-Remote-IP: 162.221.158.21 X-Policy: $RELAYED X-IronPort-AV: E=Sophos;i="5.73,341,1583211600"; d="scan'208";a="16584677" From: Andrew Cooper To: Xen-devel Subject: [PATCH 09/16] x86/cpu: Adjust enable_nmis() to be shadow stack compatible Date: Fri, 1 May 2020 23:58:31 +0100 Message-ID: <20200501225838.9866-10-andrew.cooper3@citrix.com> X-Mailer: git-send-email 2.11.0 In-Reply-To: <20200501225838.9866-1-andrew.cooper3@citrix.com> References: <20200501225838.9866-1-andrew.cooper3@citrix.com> MIME-Version: 1.0 X-BeenThere: xen-devel@lists.xenproject.org X-Mailman-Version: 2.1.29 Precedence: list List-Id: Xen developer discussion List-Unsubscribe: , List-Post: List-Help: List-Subscribe: , Cc: Andrew Cooper , Wei Liu , Jan Beulich , =?utf-8?q?Roger_Pau_Monn=C3=A9?= Errors-To: xen-devel-bounces@lists.xenproject.org Sender: "Xen-devel" When executing an IRET-to-self, the shadow stack must agree with the regular stack. We can't manipulate SSP directly, so have to fake a shadow IRET frame by executing 3 CALLs, then editing the result to look correct. This is not a fastpath, is called on the BSP long before CET can be set up, and may be called on the crash path after CET is disabled. Use the fact that INCSSP is allocated from the hint nop space to construct a test for CET being active which is safe on all processors. Signed-off-by: Andrew Cooper Reviewed-by: Jan Beulich --- CC: Jan Beulich CC: Wei Liu CC: Roger Pau Monné --- xen/include/asm-x86/processor.h | 43 +++++++++++++++++++++++++++++++---------- 1 file changed, 33 insertions(+), 10 deletions(-) diff --git a/xen/include/asm-x86/processor.h b/xen/include/asm-x86/processor.h index 54e1a8b605..654d46a6f4 100644 --- a/xen/include/asm-x86/processor.h +++ b/xen/include/asm-x86/processor.h @@ -544,17 +544,40 @@ static inline void enable_nmis(void) { unsigned long tmp; - asm volatile ( "mov %%rsp, %[tmp] \n\t" - "push %[ss] \n\t" - "push %[tmp] \n\t" - "pushf \n\t" - "push %[cs] \n\t" - "lea 1f(%%rip), %[tmp] \n\t" - "push %[tmp] \n\t" - "iretq; 1: \n\t" - : [tmp] "=&r" (tmp) + asm volatile ( "mov %%rsp, %[rsp] \n\t" + "lea .Ldone(%%rip), %[rip] \n\t" +#ifdef CONFIG_XEN_SHSTK + /* Check for CET-SS being active. */ + "mov $1, %k[ssp] \n\t" + "rdsspq %[ssp] \n\t" + "cmp $1, %k[ssp] \n\t" + "je .Lshstk_done \n\t" + + /* Push 3 words on the shadow stack */ + ".rept 3 \n\t" + "call 1f; nop; 1: \n\t" + ".endr \n\t" + + /* Fixup to be an IRET shadow stack frame */ + "wrssq %q[cs], -1*8(%[ssp]) \n\t" + "wrssq %[rip], -2*8(%[ssp]) \n\t" + "wrssq %[ssp], -3*8(%[ssp]) \n\t" + + ".Lshstk_done:" +#endif + /* Write an IRET regular frame */ + "push %[ss] \n\t" + "push %[rsp] \n\t" + "pushf \n\t" + "push %q[cs] \n\t" + "push %[rip] \n\t" + "iretq \n\t" + ".Ldone: \n\t" + : [rip] "=&r" (tmp), + [rsp] "=&r" (tmp), + [ssp] "=&r" (tmp) : [ss] "i" (__HYPERVISOR_DS), - [cs] "i" (__HYPERVISOR_CS) ); + [cs] "r" (__HYPERVISOR_CS) ); } void sysenter_entry(void);