From nobody Mon Nov 25 05:33:28 2024 Delivered-To: importer@patchew.org Authentication-Results: mx.zohomail.com; dkim=fail; spf=pass (zohomail.com: domain of gnu.org designates 209.51.188.17 as permitted sender) smtp.mailfrom=qemu-devel-bounces+importer=patchew.org@nongnu.org; dmarc=fail(p=none dis=none) header.from=ilande.co.uk Return-Path: Received: from lists.gnu.org (lists.gnu.org [209.51.188.17]) by mx.zohomail.com with SMTPS id 1717667693168406.4183047797725; Thu, 6 Jun 2024 02:54:53 -0700 (PDT) Received: from localhost ([::1] helo=lists1p.gnu.org) by lists.gnu.org with esmtp (Exim 4.90_1) (envelope-from ) id 1sF9oX-0000Cc-GG; Thu, 06 Jun 2024 05:53:45 -0400 Received: from eggs.gnu.org ([2001:470:142:3::10]) by lists.gnu.org with esmtps (TLS1.2:ECDHE_RSA_AES_256_GCM_SHA384:256) (Exim 4.90_1) (envelope-from ) id 1sF9oW-0000CM-CW for qemu-devel@nongnu.org; Thu, 06 Jun 2024 05:53:44 -0400 Received: from mail.ilande.co.uk ([2001:41c9:1:41f::167]) by eggs.gnu.org with esmtps (TLS1.2:ECDHE_RSA_AES_256_GCM_SHA384:256) (Exim 4.90_1) (envelope-from ) id 1sF9oU-0002HY-Lp for qemu-devel@nongnu.org; Thu, 06 Jun 2024 05:53:44 -0400 Received: from [2a02:8012:c93d:0:260e:bf57:a4e9:8142] (helo=cheesecake.fritz.box) by mail.ilande.co.uk with esmtpsa (TLS1.3:ECDHE_RSA_AES_256_GCM_SHA384:256) (Exim 4.92) (envelope-from ) id 1sF9nC-0004cT-03; Thu, 06 Jun 2024 10:52:25 +0100 DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=ilande.co.uk; s=20220518; h=Subject:Content-Transfer-Encoding:MIME-Version: References:In-Reply-To:Message-Id:Date:To:From:Sender:Reply-To:Cc: Content-Type:Content-ID:Content-Description:Resent-Date:Resent-From: Resent-Sender:Resent-To:Resent-Cc:Resent-Message-ID; bh=0fw8uNour2vCQNrEWKbV/I2YIRMH10+1YFPBwmXuJ3w=; b=DI4f0lIRdxeMGsRtG5iXw18rh5 bpWSCRtPQXq70NUEyPawJHrr4xBf5j5k/N8ilRfASkuyUSK/foVJb5isbt52O3sdlInkvZXSNmvYx XUTN4yYCikHECjVSOO4Z0dbJIcnJziWgU327G5XbRZU9YIlB9o/sTbZF+AjQ8FYYoTTL0DcQvTf4x 2DTfbq75TnxyBILipZYiJFIIlH/xZQE7TqDF/s7M/Ygq78FNl/Z4ok1Z6CPi6EoMj5RaWRE2tZDkS t1kXu2Qn9l/p/BVnLv8VfdSRPjyOgIgb/rOvoZtx/wIG/hh/H9x3rbQ3i1gPo3PBvRfoMBGU8rsP6 Uc6Y3YK45m8AmPK4d9TL6z0pdA2gtO22JrGM2PT8OKZgty+PUyrI3X90EYaE09XlIjGjUtJb1ZHVR KqW/tmm0xrSjWJP+Qp8A39bl8mO+XQCe6zdt3qo0nlH8ypXtUi+NDsO5Ya3JSqveoASz4yke+C0QY 1Hu8zuQFsJ0+wnlBmW23hREhINeGuGQ3S7O7gux0mnFYCjoWdWh001Ahiq+Oug9T1BBgblMgVbGLX GY5OCnjNDCTSjYvojt6DXtNVM0HZvZoTARkTZTP2Iz1ycaHDYdj2/XNIbNTWZuGkkAx75qDzn6Fud 784bw/eL00GVts/DUDS/IlYJr/0eAT6rebT+/6rgI=; From: Mark Cave-Ayland To: pbonzini@redhat.com, qemu-devel@nongnu.org Date: Thu, 6 Jun 2024 10:53:18 +0100 Message-Id: <20240606095319.229650-4-mark.cave-ayland@ilande.co.uk> X-Mailer: git-send-email 2.39.2 In-Reply-To: <20240606095319.229650-1-mark.cave-ayland@ilande.co.uk> References: <20240606095319.229650-1-mark.cave-ayland@ilande.co.uk> MIME-Version: 1.0 Content-Transfer-Encoding: quoted-printable X-SA-Exim-Connect-IP: 2a02:8012:c93d:0:260e:bf57:a4e9:8142 X-SA-Exim-Mail-From: mark.cave-ayland@ilande.co.uk Subject: [PATCH 3/4] target/i386: fix SP when taking a memory fault during POP X-SA-Exim-Version: 4.2.1 (built Wed, 08 May 2019 21:11:16 +0000) X-SA-Exim-Scanned: Yes (on mail.ilande.co.uk) Received-SPF: pass (zohomail.com: domain of gnu.org designates 209.51.188.17 as permitted sender) client-ip=209.51.188.17; envelope-from=qemu-devel-bounces+importer=patchew.org@nongnu.org; helo=lists.gnu.org; Received-SPF: pass client-ip=2001:41c9:1:41f::167; envelope-from=mark.cave-ayland@ilande.co.uk; helo=mail.ilande.co.uk X-Spam_score_int: -20 X-Spam_score: -2.1 X-Spam_bar: -- X-Spam_report: (-2.1 / 5.0 requ) BAYES_00=-1.9, DKIM_SIGNED=0.1, DKIM_VALID=-0.1, DKIM_VALID_AU=-0.1, DKIM_VALID_EF=-0.1, SPF_HELO_NONE=0.001, SPF_PASS=-0.001, T_SCC_BODY_TEXT_LINE=-0.01 autolearn=ham autolearn_force=no X-Spam_action: no action X-BeenThere: qemu-devel@nongnu.org X-Mailman-Version: 2.1.29 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Errors-To: qemu-devel-bounces+importer=patchew.org@nongnu.org Sender: qemu-devel-bounces+importer=patchew.org@nongnu.org X-ZohoMail-DKIM: fail (Header signature does not verify) X-ZM-MESSAGEID: 1717667694456100001 Content-Type: text/plain; charset="utf-8" When OS/2 Warp configures its segment descriptors, many of them are configu= red with the P flag clear to allow for a fault-on-demand implementation. In the case= where the stack value is POPped into the segment registers, the SP is incremented= before calling gen_helper_load_seg() to validate the segment descriptor: IN: 0xffef2c0c: 66 07 popl %es OP: ld_i32 loc9,env,$0xfffffffffffffff8 sub_i32 loc9,loc9,$0x1 brcond_i32 loc9,$0x0,lt,$L0 st16_i32 loc9,env,$0xfffffffffffffff8 st8_i32 $0x1,env,$0xfffffffffffffffc ---- 0000000000000c0c 0000000000000000 ext16u_i64 loc0,rsp add_i64 loc0,loc0,ss_base ext32u_i64 loc0,loc0 qemu_ld_a64_i64 loc0,loc0,noat+un+leul,5 add_i64 loc3,rsp,$0x4 deposit_i64 rsp,rsp,loc3,$0x0,$0x10 extrl_i64_i32 loc5,loc0 call load_seg,$0x0,$0,env,$0x0,loc5 add_i64 rip,rip,$0x2 ext16u_i64 rip,rip exit_tb $0x0 set_label $L0 exit_tb $0x7fff58000043 If helper_load_seg() generates a fault when validating the segment descript= or then as the SP has already been incremented, the topmost word of the stack is overw= ritten by the arguments pushed onto the stack by the CPU before taking the fault hand= ler. As a consequence things rapidly go wrong upon return from the fault handler due = to the corrupted stack. Update the logic for the existing writeback condition so that a POP into th= e segment registers also calls helper_load_seg() first before incrementing the SP, so= that if a fault occurs the SP remains unaltered. Signed-off-by: Mark Cave-Ayland Resolves: https://gitlab.com/qemu-project/qemu/-/issues/2198 --- target/i386/tcg/emit.c.inc | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) diff --git a/target/i386/tcg/emit.c.inc b/target/i386/tcg/emit.c.inc index 2d5dc11548..f905a67380 100644 --- a/target/i386/tcg/emit.c.inc +++ b/target/i386/tcg/emit.c.inc @@ -2567,7 +2567,7 @@ static void gen_POP(DisasContext *s, CPUX86State *env= , X86DecodedInsn *decode) X86DecodedOp *op =3D &decode->op[0]; MemOp ot =3D gen_pop_T0(s); =20 - if (op->has_ea) { + if (op->has_ea || op->unit =3D=3D X86_OP_SEG) { /* NOTE: order is important for MMU exceptions */ gen_writeback(s, decode, 0, s->T0); op->unit =3D X86_OP_SKIP; --=20 2.39.2