--- np2/i386c/ia32/ctrlxfer.c	2004/01/13 16:37:42	1.2
+++ np2/i386c/ia32/ctrlxfer.c	2011/12/20 09:03:28	1.22
@@ -1,5 +1,3 @@
-/*	$Id: ctrlxfer.c,v 1.2 2004/01/13 16:37:42 monaka Exp $	*/
-
 /*
  * Copyright (c) 2003 NONAKA Kimihiro
  * All rights reserved.
@@ -12,8 +10,6 @@
  * 2. Redistributions in binary form must reproduce the above copyright
  *    notice, this list of conditions and the following disclaimer in the
  *    documentation and/or other materials provided with the distribution.
- * 3. The name of the author may not be used to endorse or promote products
- *    derived from this software without specific prior written permission.
  *
  * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR
  * IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
@@ -34,22 +30,22 @@
 #include "ctrlxfer.h"
 
 
+/*------------------------------------------------------------------------------
+ * JMPfar_pm
+ */
+static void JMPfar_pm_code_segment(const selector_t *cs_sel, UINT32 new_ip);
+static void JMPfar_pm_call_gate(const selector_t *callgate_sel);
+static void JMPfar_pm_task_gate(selector_t *taskgate_sel);
+static void JMPfar_pm_tss(selector_t *tss_sel);
+
 void
-JMPfar_pm(WORD selector, DWORD new_ip)
+JMPfar_pm(UINT16 selector, UINT32 new_ip)
 {
 	selector_t jmp_sel;
-	selector_t sel2;
 	int rv;
 
-	VERBOSE(("JMPfar_pm: EIP = 0x%08x, selector = 0x%04x, new_ip = 0x%08x", CPU_PREV_EIP, selector, new_ip));
-
-	/*
-	 * IF effective address in the CS, DS, ES, FS, GS, or SS segment is illegal
-	 *     OR segment selector in target operand null
-	 *     THEN #GP(0);
-	 * FI;
-	 */
-	/* XXX */
+	VERBOSE(("JMPfar_pm: old EIP = %04x:%08x, ESP = %04x:%08x", CPU_CS, CPU_PREV_EIP, CPU_SS, CPU_ESP));
+	VERBOSE(("JMPfar_pm: selector = 0x%04x, new_ip = 0x%08x", selector, new_ip));
 
 	rv = parse_selector(&jmp_sel, selector);
 	if (rv < 0) {
@@ -57,53 +53,18 @@ JMPfar_pm(WORD selector, DWORD new_ip)
 		EXCEPTION(GP_EXCEPTION, jmp_sel.idx);
 	}
 
-	if (jmp_sel.desc.s) {
-		/* code segment descriptor */
+	if (!SEG_IS_SYSTEM(&jmp_sel.desc)) {
 		VERBOSE(("JMPfar_pm: code or data segment descriptor"));
 
-		if (!jmp_sel.desc.u.seg.c) {
+		/* check segment type */
+		if (SEG_IS_DATA(&jmp_sel.desc)) {
 			/* data segment */
 			VERBOSE(("JMPfar_pm: data segment"));
 			EXCEPTION(GP_EXCEPTION, jmp_sel.idx);
 		}
 
-		/* check privilege level */
-		if (!jmp_sel.desc.u.seg.ec) {
-			VERBOSE(("NONCONFORMING-CODE-SEGMENT"));
-			/* 下巻 p.119 4.8.1.1. */
-			if ((jmp_sel.rpl > CPU_STAT_CPL)
-			 || (jmp_sel.desc.dpl != CPU_STAT_CPL)) {
-				VERBOSE(("JMPfar_pm: RPL(%d) > CPL(%d) or DPL(%d) != CPL(%d)", jmp_sel.rpl, CPU_STAT_CPL, jmp_sel.desc.dpl, CPU_STAT_CPL));
-				EXCEPTION(GP_EXCEPTION, jmp_sel.idx);
-			}
-		} else {
-			VERBOSE(("CONFORMING-CODE-SEGMENT"));
-			/* 下巻 p.120 4.8.1.2. */
-			if (jmp_sel.desc.dpl > CPU_STAT_CPL) {
-				VERBOSE(("JMPfar_pm: DPL(%d) > CPL(%d)", jmp_sel.desc.dpl, CPU_STAT_CPL));
-				EXCEPTION(GP_EXCEPTION, jmp_sel.idx);
-			}
-		}
-
-		/* not present */
-		if (selector_is_not_present(&jmp_sel)) {
-			VERBOSE(("JMPfar_pm: selector is not present"));
-			EXCEPTION(NP_EXCEPTION, jmp_sel.idx);
-		}
-
-		if (!CPU_INST_OP32) {
-			new_ip &= 0xffff;
-		}
-
-		/* out of range */
-		if (new_ip > jmp_sel.desc.u.seg.limit) {
-			VERBOSE(("JMPfar_pm: new_ip is out of range. new_ip = %08x, limit = %08x", new_ip, jmp_sel.desc.u.seg.limit));
-			EXCEPTION(GP_EXCEPTION, 0);
-		}
-
-		VERBOSE(("JMPfar_pm: new CS = %04x, EIP = %08x", jmp_sel.selector, new_ip));
-		load_cs(jmp_sel.selector, &jmp_sel.desc, CPU_STAT_CPL);
-		SET_EIP(new_ip);
+		/* code segment descriptor */
+		JMPfar_pm_code_segment(&jmp_sel, new_ip);
 	} else {
 		/* system descriptor */
 		VERBOSE(("JMPfar_pm: system descriptor"));
@@ -111,159 +72,16 @@ JMPfar_pm(WORD selector, DWORD new_ip)
 		switch (jmp_sel.desc.type) {
 		case CPU_SYSDESC_TYPE_CALL_16:
 		case CPU_SYSDESC_TYPE_CALL_32:
-			VERBOSE(("CALL-GATE"));
-
-			/* check privilege level */
-			if ((jmp_sel.desc.dpl < CPU_STAT_CPL)
-			 || (jmp_sel.desc.dpl < jmp_sel.rpl)) {
-				VERBOSE(("JMPfar_pm: DPL(%d) < CPL(%d) or DPL(%d) < RPL(%d)", jmp_sel.desc.dpl, CPU_STAT_CPL, jmp_sel.desc.dpl, jmp_sel.rpl));
-				EXCEPTION(GP_EXCEPTION, jmp_sel.idx);
-			}
-
-			/* not present */
-			if (selector_is_not_present(&jmp_sel)) {
-				VERBOSE(("JMPfar_pm: selector is not present"));
-				EXCEPTION(NP_EXCEPTION, jmp_sel.idx);
-			}
-
-			/* parse call gate selector */
-			rv = parse_selector(&sel2, jmp_sel.desc.u.gate.selector);
-			if (rv < 0) {
-				VERBOSE(("JMPfar_pm: parse_selector (selector = %04x, rv = %d)", jmp_sel.desc.u.gate.selector, rv));
-				EXCEPTION(GP_EXCEPTION, sel2.idx);
-			}
-
-			/* check code segment descriptor */
-			if (!sel2.desc.s || !sel2.desc.u.seg.c) {
-				VERBOSE(("JMPfar_pm: not code segment (%s, %s)", sel2.desc.s ? "code/data" : "system", sel2.desc.u.seg.c ? "code" : "data"));
-				EXCEPTION(GP_EXCEPTION, sel2.idx);
-			}
-
-			/* check privilege level */
-			if (!sel2.desc.u.seg.ec) {
-				/* 下巻 p.119 4.8.1.1. */
-				if ((sel2.rpl > CPU_STAT_CPL)
-				 || (sel2.desc.dpl != CPU_STAT_CPL)) {
-					VERBOSE(("JMPfar_pm: RPL(%d) > CPL(%d) or DPL(%d) != CPL(%d)", sel2.rpl, CPU_STAT_CPL, sel2.desc.dpl, CPU_STAT_CPL));
-					EXCEPTION(GP_EXCEPTION, sel2.idx);
-				}
-			} else {
-				/* 下巻 p.120 4.8.1.2. */
-				if (sel2.desc.dpl > CPU_STAT_CPL) {
-					VERBOSE(("JMPfar_pm: DPL(%d) > CPL(%d)", sel2.desc.dpl, CPU_STAT_CPL));
-					EXCEPTION(GP_EXCEPTION, sel2.idx);
-				}
-			}
-
-			/* not present */
-			if (selector_is_not_present(&sel2)) {
-				VERBOSE(("JMPfar_pm: selector is not present"));
-				EXCEPTION(NP_EXCEPTION, sel2.idx);
-			}
-
-			new_ip = jmp_sel.desc.u.gate.offset;
-			if (jmp_sel.desc.type == CPU_SYSDESC_TYPE_CALL_16) {
-				new_ip &= 0xffff;
-			}
-
-			/* out of range */
-			if (new_ip > sel2.desc.u.seg.limit) {
-				VERBOSE(("JMPfar_pm: new_ip is out of range. new_ip = %08x, limit = %08x", new_ip, sel2.desc.u.seg.limit));
-				EXCEPTION(GP_EXCEPTION, 0);
-			}
-
-			VERBOSE(("JMPfar_pm: new CS = %04x, EIP = %08x", sel2.selector, new_ip));
-			load_cs(sel2.selector, &sel2.desc, CPU_STAT_CPL);
-			SET_EIP(new_ip);
+			JMPfar_pm_call_gate(&jmp_sel);
 			break;
 
-		/*
-		 * 中巻 p.373 JMP 命令
-		 *
-		 * JMP 命令でタスク・スイッチを実行するときは EFLAGS レジスタに
-		 * ネストされたタスク・フラグ (NT) がセットされず、新しい TSS の
-		 * 以前のタスク・リンク・フィールドに前のタスクの TSS セレクタが
-		 * ロードされないので注意されたい。したがって、前のタスクへの
-		 * リターンは IRET 命令の実行では実現できない。JMP 命令で
-		 * タスク・スイッチを実行するのは、その点で CALL 命令と異なる。
-		 * すなわち、CALL 命令は NT フラグをセットし、以前の
-		 * タスク・リンク情報をセーブするので、IRET 命令でのコール元
-		 * タスクへのリターンが可能になる。
-		 */
 		case CPU_SYSDESC_TYPE_TASK:
-			VERBOSE(("TASK-GATE"));
-
-			/* check privilege level */
-			if ((jmp_sel.desc.dpl < CPU_STAT_CPL)
-			 || (jmp_sel.desc.dpl < jmp_sel.rpl)) {
-				VERBOSE(("JMPfar_pm: DPL(%d) < CPL(%d) or DPL(%d) < RPL(%d)", jmp_sel.desc.dpl, CPU_STAT_CPL, jmp_sel.desc.dpl, jmp_sel.rpl));
-				EXCEPTION(GP_EXCEPTION, jmp_sel.idx);
-			}
-
-			/* not present */
-			if (selector_is_not_present(&jmp_sel)) {
-				VERBOSE(("JMPfar_pm: selector is not present"));
-				EXCEPTION(NP_EXCEPTION, jmp_sel.idx);
-			}
-
-			/* parse call tss selector */
-			rv = parse_selector(&sel2, jmp_sel.desc.u.gate.selector);
-			if (rv < 0 || sel2.ldt) {
-				VERBOSE(("JMPfar_pm: parse_selector (selector = %04x, rv = %d, %s)", jmp_sel.desc.u.gate.selector, rv, sel2.ldt ? "LDT" : "GDT"));
-				EXCEPTION(GP_EXCEPTION, sel2.idx);
-			}
-
-			/* check descriptor type */
-			switch (sel2.desc.type) {
-			case CPU_SYSDESC_TYPE_TSS_16:
-			case CPU_SYSDESC_TYPE_TSS_32:
-				break;
-
-			default:
-				VERBOSE(("JMPfar_pm: invalid descriptor type (type = %d)", sel2.desc.type));
-				EXCEPTION(GP_EXCEPTION, sel2.idx);
-				break;
-			}
-
-			/* not present */
-			if (selector_is_not_present(&sel2)) {
-				VERBOSE(("JMPfar_pm: selector is not present"));
-				EXCEPTION(NP_EXCEPTION, sel2.idx);
-			}
-
-			task_switch(&sel2, TASK_SWITCH_JMP);
-
-			/* out of range */
-			if (CPU_EIP > CPU_STAT_CS_LIMIT) {
-				VERBOSE(("JMPfar_pm: new_ip is out of range. new_ip = %08x, limit = %08x", CPU_EIP, CPU_STAT_CS_LIMIT));
-				EXCEPTION(GP_EXCEPTION, 0);
-			}
+			JMPfar_pm_task_gate(&jmp_sel);
 			break;
 
 		case CPU_SYSDESC_TYPE_TSS_16:
 		case CPU_SYSDESC_TYPE_TSS_32:
-			VERBOSE(("TASK-STATE-SEGMENT"));
-
-			/* check privilege level */
-			if ((jmp_sel.desc.dpl < CPU_STAT_CPL)
-			 || (jmp_sel.desc.dpl < jmp_sel.rpl)) {
-				VERBOSE(("JMPfar_pm: DPL(%d) < CPL(%d) or DPL(%d) < RPL(%d)", jmp_sel.desc.dpl, CPU_STAT_CPL, jmp_sel.desc.dpl, jmp_sel.rpl));
-				EXCEPTION(TS_EXCEPTION, jmp_sel.idx);
-			}
-
-			/* not present */
-			if (selector_is_not_present(&jmp_sel)) {
-				VERBOSE(("JMPfar_pm: selector is not present"));
-				EXCEPTION(NP_EXCEPTION, jmp_sel.idx);
-			}
-
-			task_switch(&jmp_sel, TASK_SWITCH_JMP);
-
-			/* out of range */
-			if (CPU_EIP > CPU_STAT_CS_LIMIT) {
-				VERBOSE(("JMPfar_pm: new_ip is out of range. new_ip = %08x, limit = %08x", CPU_EIP, CPU_STAT_CS_LIMIT));
-				EXCEPTION(GP_EXCEPTION, 0);
-			}
+			JMPfar_pm_tss(&jmp_sel);
 			break;
 
 		case CPU_SYSDESC_TYPE_TSS_BUSY_16:
@@ -271,331 +89,292 @@ JMPfar_pm(WORD selector, DWORD new_ip)
 			VERBOSE(("JMPfar_pm: task is busy"));
 			/*FALLTHROUGH*/
 		default:
-			VERBOSE(("JMPfar_pm: invalid descriptor type (type = %d)", sel2.desc.type));
+			VERBOSE(("JMPfar_pm: invalid descriptor type (type = %d)", jmp_sel.desc.type));
 			EXCEPTION(GP_EXCEPTION, jmp_sel.idx);
 			break;
 		}
 	}
+
+	VERBOSE(("JMPfar_pm: new EIP = %04x:%08x, ESP = %04x:%08x", CPU_CS, CPU_EIP, CPU_SS, CPU_ESP));
 }
 
-/*
- * 4.3.6. 特権レベル間のコール操作
- *
- * 1. アクセス権のチェック(特権チェック)を実行する。
- * 2. SS, ESP, CS, EIP の各レジスタの現在地を一時的に内部にセーブする。
- * 3. TSS レジスタに格納されている新しいスタック(すなわち、現在コールされている
- *    特権レベル用のスタック)のセグメントレジスタとスタックポインタを
- *    SS レジスタと ESP レジスタにロードし、新しいスタックに切り替える。
- * 4. コール元プロシージャのスタックに対して一時的にセーブしておいた SS 値と
- *    ESP 値を、この新しいスタックにプッシュする。
- * 5. コール元プロシージャのスタックからパラメータをコピーする。新しいスタック
- *    にコピーされるパラメータの数は、コール・ゲート・ディスクリプタ内の値で
- *    決まる。
- * 6. コール元プロシージャに対して一時的にセーブしておいた CS 値と EIP 値を、
- *    新しいスタックにプッシュする。
- * 7. 新しいコード・セグメントのセグメント・セレクタと新しい命令ポインタを、
- *    コール・ゲートから CS レジスタと EIP レジスタにそれぞれロードする。
- * 8. コールされたプロシージャの実行を新しい特権レベルで開始する。
+/*---
+ * JMPfar: code segment
  */
-void
-CALLfar_pm(WORD selector, DWORD new_ip)
+static void
+JMPfar_pm_code_segment(const selector_t *cs_sel, UINT32 new_ip)
 {
-	selector_t call_sel;
-	selector_t sel2;
+
+	VERBOSE(("JMPfar_pm: CODE-SEGMENT"));
+
+	/* check privilege level */
+	if (!SEG_IS_CONFORMING_CODE(&cs_sel->desc)) {
+		VERBOSE(("JMPfar_pm: NON-CONFORMING-CODE-SEGMENT"));
+		/* 下巻 p.119 4.8.1.1. */
+		if (cs_sel->rpl > CPU_STAT_CPL) {
+			VERBOSE(("JMPfar_pm: RPL(%d) > CPL(%d)", cs_sel->rpl, CPU_STAT_CPL));
+			EXCEPTION(GP_EXCEPTION, cs_sel->idx);
+		}
+		if (cs_sel->desc.dpl != CPU_STAT_CPL) {
+			VERBOSE(("JMPfar_pm: DPL(%d) != CPL(%d)", cs_sel->desc.dpl, CPU_STAT_CPL));
+			EXCEPTION(GP_EXCEPTION, cs_sel->idx);
+		}
+	} else {
+		VERBOSE(("JMPfar_pm: CONFORMING-CODE-SEGMENT"));
+		/* 下巻 p.120 4.8.1.2. */
+		if (cs_sel->desc.dpl > CPU_STAT_CPL) {
+			VERBOSE(("JMPfar_pm: DPL(%d) > CPL(%d)", cs_sel->desc.dpl, CPU_STAT_CPL));
+			EXCEPTION(GP_EXCEPTION, cs_sel->idx);
+		}
+	}
+
+	/* not present */
+	if (selector_is_not_present(cs_sel)) {
+		VERBOSE(("JMPfar_pm: code selector is not present"));
+		EXCEPTION(NP_EXCEPTION, cs_sel->idx);
+	}
+
+	/* out of range */
+	if (new_ip > cs_sel->desc.u.seg.limit) {
+		VERBOSE(("JMPfar_pm: new_ip is out of range. new_ip = %08x, limit = %08x", new_ip, cs_sel->desc.u.seg.limit));
+		EXCEPTION(GP_EXCEPTION, 0);
+	}
+
+	load_cs(cs_sel->selector, &cs_sel->desc, CPU_STAT_CPL);
+	CPU_EIP = new_ip;
+}
+
+/*---
+ * JMPfar: call gate
+ */
+static void
+JMPfar_pm_call_gate(const selector_t *callgate_sel)
+{
+	selector_t cs_sel;
 	int rv;
 
-	VERBOSE(("CALLfar_pm: EIP = 0x%08x, selector = 0x%04x, new_ip = 0x%08x", CPU_PREV_EIP, selector, new_ip));
+	VERBOSE(("JMPfar_pm: CALL-GATE"));
 
-	rv = parse_selector(&call_sel, selector);
-	if (rv < 0) {
-		EXCEPTION(GP_EXCEPTION, call_sel.idx);
+	/* check privilege level */
+	if (callgate_sel->desc.dpl < CPU_STAT_CPL) {
+		VERBOSE(("JMPfar_pm: DPL(%d) < CPL(%d)", callgate_sel->desc.dpl, CPU_STAT_CPL));
+		EXCEPTION(GP_EXCEPTION, callgate_sel->idx);
+	}
+	if (callgate_sel->desc.dpl < callgate_sel->rpl) {
+		VERBOSE(("JMPfar_pm: DPL(%d) < RPL(%d)",  callgate_sel->desc.dpl, callgate_sel->rpl));
+		EXCEPTION(GP_EXCEPTION, callgate_sel->idx);
 	}
 
-	if (call_sel.desc.s) {
-		/* code segment descriptor */
-		if (!call_sel.desc.u.seg.c) {
-			/* data segment */
-			EXCEPTION(GP_EXCEPTION, call_sel.idx);
-		}
+	/* not present */
+	if (selector_is_not_present(callgate_sel)) {
+		VERBOSE(("JMPfar_pm: call gate selector is not present"));
+		EXCEPTION(NP_EXCEPTION, callgate_sel->idx);
+	}
 
-		/* check privilege level */
-		if (!call_sel.desc.u.seg.ec) {
-			VERBOSE(("NONCONFORMING-CODE-SEGMENT"));
+	/* parse code segment selector */
+	rv = parse_selector(&cs_sel, callgate_sel->desc.u.gate.selector);
+	if (rv < 0) {
+		VERBOSE(("JMPfar_pm: parse_selector (selector = %04x, rv = %d)", callgate_sel->desc.u.gate.selector, rv));
+		EXCEPTION(GP_EXCEPTION, cs_sel.idx);
+	}
 
-			/* 下巻 p.119 4.8.1.1. */
-			if ((call_sel.rpl > CPU_STAT_CPL)
-			 || (call_sel.desc.dpl != CPU_STAT_CPL)) {
-				EXCEPTION(GP_EXCEPTION, call_sel.idx);
-			}
-		} else {
-			VERBOSE(("CONFORMING-CODE-SEGMENT"));
+	/* check segment type */
+	if (SEG_IS_SYSTEM(&cs_sel.desc)) {
+		VERBOSE(("JMPfar_pm: code segment is system segment"));
+		EXCEPTION(GP_EXCEPTION, cs_sel.idx);
+	}
+	if (SEG_IS_DATA(&cs_sel.desc)) {
+		VERBOSE(("JMPfar_pm: code segment is data segment"));
+		EXCEPTION(GP_EXCEPTION, cs_sel.idx);
+	}
 
-			/* 下巻 p.120 4.8.1.2. */
-			if (call_sel.desc.dpl > CPU_STAT_CPL) {
-				EXCEPTION(GP_EXCEPTION, call_sel.idx);
-			}
+	/* check privilege level */
+	if (!SEG_IS_CONFORMING_CODE(&cs_sel.desc)) {
+		/* 下巻 p.119 4.8.1.1. */
+		if (cs_sel.rpl > CPU_STAT_CPL) {
+			VERBOSE(("JMPfar_pm: RPL(%d) > CPL(%d)", cs_sel.rpl, CPU_STAT_CPL));
+			EXCEPTION(GP_EXCEPTION, cs_sel.idx);
+		}
+		if (cs_sel.desc.dpl != CPU_STAT_CPL) {
+			VERBOSE(("JMPfar_pm: DPL(%d) != CPL(%d)", cs_sel.desc.dpl, CPU_STAT_CPL));
+			EXCEPTION(GP_EXCEPTION, cs_sel.idx);
 		}
-
-		/* not present */
-		if (selector_is_not_present(&call_sel)) {
-			EXCEPTION(NP_EXCEPTION, call_sel.idx);
+	} else {
+		/* 下巻 p.120 4.8.1.2. */
+		if (cs_sel.desc.dpl > CPU_STAT_CPL) {
+			VERBOSE(("JMPfar_pm: DPL(%d) > CPL(%d)", cs_sel.desc.dpl, CPU_STAT_CPL));
+			EXCEPTION(GP_EXCEPTION, cs_sel.idx);
 		}
+	}
 
-		if (CPU_INST_OP32) {
-			CHECK_STACK_PUSH(&CPU_STAT_SREG(CPU_SS_INDEX), CPU_ESP, 8);
-			/* out of range */
-			if (new_ip > call_sel.desc.u.seg.limit) {
-				EXCEPTION(GP_EXCEPTION, 0);
-			}
+	/* not present */
+	if (selector_is_not_present(&cs_sel)) {
+		VERBOSE(("JMPfar_pm: code selector is not present"));
+		EXCEPTION(NP_EXCEPTION, cs_sel.idx);
+	}
 
-			PUSH0_32(CPU_CS);
-			PUSH0_32(CPU_EIP);
-		} else {
-			CHECK_STACK_PUSH(&CPU_STAT_SREG(CPU_SS_INDEX), CPU_ESP, 4);
-			/* out of range */
-			if (new_ip > call_sel.desc.u.seg.limit) {
-				EXCEPTION(GP_EXCEPTION, 0);
-			}
+	/* out of range */
+	if (callgate_sel->desc.u.gate.offset > cs_sel.desc.u.seg.limit) {
+		VERBOSE(("JMPfar_pm: new_ip is out of range. new_ip = %08x, limit = %08x", callgate_sel->desc.u.gate.offset, cs_sel.desc.u.seg.limit));
+		EXCEPTION(GP_EXCEPTION, 0);
+	}
 
-			PUSH0_16(CPU_CS);
-			PUSH0_16(CPU_IP);
-		}
+	load_cs(cs_sel.selector, &cs_sel.desc, CPU_STAT_CPL);
+	CPU_EIP = callgate_sel->desc.u.gate.offset;
+}
 
-		if (!call_sel.desc.d) {
-			new_ip &= 0xffff;
-		}
+/*---
+ * JMPfar: task gate
+ */
+static void
+JMPfar_pm_task_gate(selector_t *taskgate_sel)
+{
+	selector_t tss_sel;
+	int rv;
 
-		load_cs(call_sel.selector, &call_sel.desc, CPU_STAT_CPL);
-		SET_EIP(new_ip);
-	} else {
-		DWORD temp_eip, temp_esp;
-		WORD temp_cs, temp_ss;
+	VERBOSE(("JMPfar_pm: TASK-GATE"));
 
-		/* system descriptor */
-		switch (call_sel.desc.type) {
-		case CPU_SYSDESC_TYPE_CALL_16:
-		case CPU_SYSDESC_TYPE_CALL_32:
-			VERBOSE(("CALL-GATE"));
+	/* check privilege level */
+	if (taskgate_sel->desc.dpl < CPU_STAT_CPL) {
+		VERBOSE(("JMPfar_pm: DPL(%d) < CPL(%d)", taskgate_sel->desc.dpl, CPU_STAT_CPL));
+		EXCEPTION(GP_EXCEPTION, taskgate_sel->idx);
+	}
+	if (taskgate_sel->desc.dpl < taskgate_sel->rpl) {
+		VERBOSE(("JMPfar_pm: DPL(%d) < RPL(%d)", taskgate_sel->desc.dpl, taskgate_sel->rpl));
+		EXCEPTION(GP_EXCEPTION, taskgate_sel->idx);
+	}
 
-			/* check privilege level */
-			if ((call_sel.desc.dpl < CPU_STAT_CPL)
-			 || (call_sel.desc.dpl < call_sel.rpl)) {
-				EXCEPTION(GP_EXCEPTION, call_sel.idx);
-			}
+	/* not present */
+	if (selector_is_not_present(taskgate_sel)) {
+		VERBOSE(("JMPfar_pm: selector is not present"));
+		EXCEPTION(NP_EXCEPTION, taskgate_sel->idx);
+	}
 
-			/* not present */
-			if (selector_is_not_present(&call_sel)) {
-				EXCEPTION(NP_EXCEPTION, call_sel.idx);
-			}
+	/* parse tss selector */
+	rv = parse_selector(&tss_sel, taskgate_sel->desc.u.gate.selector);
+	if (rv < 0 || tss_sel.ldt) {
+		VERBOSE(("JMPfar_pm: parse_selector (selector = %04x, rv = %d, %cDT)", taskgate_sel->desc.u.gate.selector, rv, tss_sel.ldt ? 'L' : 'G'));
+		EXCEPTION(GP_EXCEPTION, tss_sel.idx);
+	}
 
-			/* parse code segment descriptor */
-			rv = parse_selector(&sel2, call_sel.desc.u.gate.selector);
-			if (rv < 0) {
-				EXCEPTION(GP_EXCEPTION, sel2.idx);
-			}
+	/* check descriptor type */
+	switch (tss_sel.desc.type) {
+	case CPU_SYSDESC_TYPE_TSS_16:
+	case CPU_SYSDESC_TYPE_TSS_32:
+		break;
+
+	case CPU_SYSDESC_TYPE_TSS_BUSY_16:
+	case CPU_SYSDESC_TYPE_TSS_BUSY_32:
+		VERBOSE(("JMPfar_pm: task is busy"));
+		/*FALLTHROUGH*/
+	default:
+		VERBOSE(("JMPfar_pm: invalid descriptor type (type = %d)", tss_sel.desc.type));
+		EXCEPTION(GP_EXCEPTION, tss_sel.idx);
+		break;
+	}
 
-			/* check code segment & privilege level */
-			if (!sel2.desc.s
-			 || !sel2.desc.u.seg.c
-			 || sel2.desc.dpl > CPU_STAT_CPL) {
-				EXCEPTION(GP_EXCEPTION, sel2.idx);
-			}
+	/* not present */
+	if (selector_is_not_present(&tss_sel)) {
+		VERBOSE(("JMPfar_pm: selector is not present"));
+		EXCEPTION(NP_EXCEPTION, tss_sel.idx);
+	}
 
-			/* not present */
-			if (selector_is_not_present(&sel2)) {
-				EXCEPTION(NP_EXCEPTION, sel2.idx);
-			}
+	task_switch(&tss_sel, TASK_SWITCH_JMP);
 
-			/* save register */
-			temp_cs = CPU_CS;
-			temp_ss = CPU_SS;
-			temp_eip = CPU_EIP;
-			temp_esp = CPU_ESP;
-			if (sel2.desc.type == CPU_SYSDESC_TYPE_CALL_16) {
-				temp_eip &= 0xffff;
-				temp_esp &= 0xffff;
-			}
+	/* out of range */
+	if (CPU_EIP > CPU_STAT_CS_LIMIT) {
+		VERBOSE(("JMPfar_pm: new_ip is out of range. new_ip = %08x, limit = %08x", CPU_EIP, CPU_STAT_CS_LIMIT));
+		EXCEPTION(GP_EXCEPTION, 0);
+	}
+}
 
-			new_ip = call_sel.desc.u.gate.offset;
+/*---
+ * JMPfar: TSS
+ */
+static void
+JMPfar_pm_tss(selector_t *tss_sel)
+{
 
-			/* out of range */
-			if (new_ip > sel2.desc.u.seg.limit) {
-				EXCEPTION(GP_EXCEPTION, 0);
-			}
+	VERBOSE(("JMPfar_pm: TASK-STATE-SEGMENT"));
 
-			if (!sel2.desc.u.seg.ec
-			 && (sel2.desc.dpl < CPU_STAT_CPL)) {
-				DWORD param[32];	// copy param
-				selector_t ss_sel;
-				DWORD tss_esp;
-				WORD tss_ss;
-				BYTE i;
-
-				VERBOSE(("MORE-PRIVILEGE"));
-
-				get_stack_from_tss(sel2.desc.dpl, &tss_ss, &tss_esp);
-
-				/* parse stack segment descriptor */
-				rv = parse_selector(&ss_sel, tss_ss);
-				if (rv < 0) {
-					EXCEPTION(TS_EXCEPTION, ss_sel.idx);
-				}
-
-				/* check privilege level */
-				if ((ss_sel.rpl != sel2.desc.dpl)
-				 || (ss_sel.desc.dpl != sel2.desc.dpl)
-				 || !ss_sel.desc.s
-				 || !ss_sel.desc.u.seg.wr) {
-					EXCEPTION(TS_EXCEPTION, ss_sel.idx);
-				}
-
-				/* not present */
-				if (selector_is_not_present(&ss_sel)) {
-					EXCEPTION(NP_EXCEPTION, ss_sel.idx);
-				}
-
-				if (call_sel.desc.type == CPU_SYSDESC_TYPE_CALL_32){
-					CHECK_STACK_PUSH(&ss_sel.desc, tss_esp, 16 + sel2.desc.u.gate.count * 4);
-
-					/* dump param */
-					for (i = 0; i < sel2.desc.u.gate.count; i++) {
-						param[i] = cpu_vmemoryread_d(CPU_SS_INDEX, CPU_ESP + i * 4);
-					}
-
-					load_ss(tss_ss, &ss_sel.desc, ss_sel.desc.dpl);
-					CPU_ESP = tss_esp;
-					load_cs(sel2.selector, &sel2.desc, sel2.desc.dpl);
-					SET_EIP(new_ip);
-
-					PUSH0_32(temp_ss);
-					PUSH0_32(temp_esp);
-
-					/* restore param */
-					for (i = sel2.desc.u.gate.count; i != 0; i--) {
-						PUSH0_32(param[i - 1]);
-					}
-
-					PUSH0_32(temp_cs);
-					PUSH0_32(temp_eip);
-				} else {
-					CHECK_STACK_PUSH(&ss_sel.desc, tss_esp, 8 + sel2.desc.u.gate.count * 2);
-
-					new_ip &= 0xffff;
-
-					/* dump param */
-					for (i = 0; i < sel2.desc.u.gate.count; i++) {
-						param[i] = cpu_vmemoryread_w(CPU_SS_INDEX, CPU_ESP + i * 2);
-					}
-
-					load_ss(tss_ss, &ss_sel.desc, ss_sel.desc.dpl);
-					CPU_ESP = tss_esp & 0xffff;
-					load_cs(sel2.selector, &sel2.desc, sel2.desc.dpl);
-					SET_EIP(new_ip);
-
-					PUSH0_16(temp_ss);
-					PUSH0_16(temp_esp);
-
-					/* restore param */
-					for (i = sel2.desc.u.gate.count; i != 0; i--) {
-						PUSH0_16(param[i - 1]);
-					}
-
-					PUSH0_16(temp_cs);
-					PUSH0_16(temp_eip);
-				}
-			} else {
-				VERBOSE(("SAME-PRIVILEGE"));
-
-				if (call_sel.desc.type == CPU_SYSDESC_TYPE_CALL_32){
-					CHECK_STACK_PUSH(&CPU_STAT_SREG(CPU_SS_INDEX), CPU_ESP, 8);
-
-					load_cs(sel2.selector, &sel2.desc, CPU_STAT_CPL);
-					SET_EIP(new_ip);
-
-					PUSH0_32(temp_cs);
-					PUSH0_32(temp_eip);
-				} else {
-					CHECK_STACK_PUSH(&CPU_STAT_SREG(CPU_SS_INDEX), CPU_ESP, 4);
-
-					load_cs(sel2.selector, &sel2.desc, CPU_STAT_CPL);
-					new_ip &= 0xffff;
-					SET_EIP(new_ip);
-
-					PUSH0_16(temp_cs);
-					PUSH0_16(temp_eip);
-				}
-			}
-			break;
+	/* check privilege level */
+	if (tss_sel->desc.dpl < CPU_STAT_CPL) {
+		VERBOSE(("JMPfar_pm: DPL(%d) < CPL(%d)", tss_sel->desc.dpl, CPU_STAT_CPL));
+		EXCEPTION(GP_EXCEPTION, tss_sel->idx);
+	}
+	if (tss_sel->desc.dpl < tss_sel->rpl) {
+		VERBOSE(("JMPfar_pm: DPL(%d) < RPL(%d)", tss_sel->desc.dpl, tss_sel->rpl));
+		EXCEPTION(GP_EXCEPTION, tss_sel->idx);
+	}
 
-		case CPU_SYSDESC_TYPE_TASK:
-			VERBOSE(("TASK-GATE"));
+	/* not present */
+	if (selector_is_not_present(tss_sel)) {
+		VERBOSE(("JMPfar_pm: selector is not present"));
+		EXCEPTION(NP_EXCEPTION, tss_sel->idx);
+	}
 
-			/* check privilege level */
-			if ((call_sel.desc.dpl < CPU_STAT_CPL)
-			 || (call_sel.desc.dpl < call_sel.rpl)) {
-				EXCEPTION(GP_EXCEPTION, call_sel.idx);
-			}
+	task_switch(tss_sel, TASK_SWITCH_JMP);
 
-			/* not present */
-			if (selector_is_not_present(&call_sel)) {
-				EXCEPTION(NP_EXCEPTION, call_sel.idx);
-			}
+	/* out of range */
+	if (CPU_EIP > CPU_STAT_CS_LIMIT) {
+		VERBOSE(("JMPfar_pm: new_ip is out of range. new_ip = %08x, limit = %08x", CPU_EIP, CPU_STAT_CS_LIMIT));
+		EXCEPTION(GP_EXCEPTION, 0);
+	}
+}
 
-			/* tss descriptor */
-			rv = parse_selector(&sel2, call_sel.desc.u.gate.selector);
-			if (rv < 0 || sel2.ldt) {
-				EXCEPTION(GP_EXCEPTION, sel2.idx);
-			}
 
-			/* check descriptor type */
-			switch (sel2.desc.type) {
-			case CPU_SYSDESC_TYPE_TSS_16:
-			case CPU_SYSDESC_TYPE_TSS_32:
-				break;
-
-			case CPU_SYSDESC_TYPE_TSS_BUSY_16:
-			case CPU_SYSDESC_TYPE_TSS_BUSY_32:
-				VERBOSE(("CALLfar_pm: task is busy"));
-				/*FALLTHROUGH*/
-			default:
-				EXCEPTION(GP_EXCEPTION, sel2.idx);
-				break;
-			}
+/*------------------------------------------------------------------------------
+ * CALLfar_pm
+ */
+static void CALLfar_pm_code_segment(const selector_t *cs_sel, UINT32 new_ip);
+static void CALLfar_pm_call_gate(const selector_t *callgate_sel);
+static void CALLfar_pm_task_gate(selector_t *taskgate_sel);
+static void CALLfar_pm_tss(selector_t *tss_sel);
 
-			/* not present */
-			if (selector_is_not_present(&sel2)) {
-				EXCEPTION(NP_EXCEPTION, sel2.idx);
-			}
+void
+CALLfar_pm(UINT16 selector, UINT32 new_ip)
+{
+	selector_t call_sel;
+	int rv;
 
-			task_switch(&sel2, TASK_SWITCH_CALL);
+	VERBOSE(("CALLfar_pm: old EIP = %04x:%08x, ESP = %04x:%08x", CPU_CS, CPU_PREV_EIP, CPU_SS, CPU_ESP));
+	VERBOSE(("CALLfar_pm: selector = 0x%04x, new_ip = 0x%08x", selector, new_ip));
 
-			/* out of range */
-			if (CPU_EIP > CPU_STAT_CS_LIMIT) {
-				EXCEPTION(GP_EXCEPTION, 0);
-			}
-			break;
+	rv = parse_selector(&call_sel, selector);
+	if (rv < 0) {
+		VERBOSE(("CALLfar_pm: parse_selector (selector = %04x, rv = %d)", selector, rv));
+		EXCEPTION(GP_EXCEPTION, call_sel.idx);
+	}
 
-		case CPU_SYSDESC_TYPE_TSS_16:
-		case CPU_SYSDESC_TYPE_TSS_32:
-			VERBOSE(("TASK-STATE-SEGMENT"));
+	if (!SEG_IS_SYSTEM(&call_sel.desc)) {
+		/* code or data segment descriptor */
+		VERBOSE(("CALLfar_pm: code or data segment descriptor"));
 
-			/* check privilege level */
-			if ((call_sel.desc.dpl < CPU_STAT_CPL)
-			 || (call_sel.desc.dpl < call_sel.rpl)) {
-				EXCEPTION(GP_EXCEPTION, call_sel.idx);
-			}
+		if (SEG_IS_DATA(&call_sel.desc)) {
+			/* data segment */
+			VERBOSE(("CALLfar_pm: data segment"));
+			EXCEPTION(GP_EXCEPTION, call_sel.idx);
+		}
 
-			/* not present */
-			if (selector_is_not_present(&call_sel)) {
-				EXCEPTION(NP_EXCEPTION, call_sel.idx);
-			}
+		/* code segment descriptor */
+		CALLfar_pm_code_segment(&call_sel, new_ip);
+	} else {
+		/* system descriptor */
+		VERBOSE(("CALLfar_pm: system descriptor"));
 
-			task_switch(&call_sel, TASK_SWITCH_CALL);
+		switch (call_sel.desc.type) {
+		case CPU_SYSDESC_TYPE_CALL_16:
+		case CPU_SYSDESC_TYPE_CALL_32:
+			CALLfar_pm_call_gate(&call_sel);
+			break;
 
-			/* out of range */
-			if (CPU_EIP > CPU_STAT_CS_LIMIT) {
-				EXCEPTION(GP_EXCEPTION, 0);
-			}
+		case CPU_SYSDESC_TYPE_TASK:
+			CALLfar_pm_task_gate(&call_sel);
+			break;
+
+		case CPU_SYSDESC_TYPE_TSS_16:
+		case CPU_SYSDESC_TYPE_TSS_32:
+			CALLfar_pm_tss(&call_sel);
 			break;
 
 		case CPU_SYSDESC_TYPE_TSS_BUSY_16:
@@ -603,427 +382,1043 @@ CALLfar_pm(WORD selector, DWORD new_ip)
 			VERBOSE(("CALLfar_pm: task is busy"));
 			/*FALLTHROUGH*/
 		default:
+			VERBOSE(("CALLfar_pm: invalid descriptor type (type = %d)", call_sel.desc.type));
 			EXCEPTION(GP_EXCEPTION, call_sel.idx);
 			break;
 		}
 	}
+
+	VERBOSE(("CALLfar_pm: new EIP = %04x:%08x, new ESP = %04x:%08x", CPU_CS, CPU_EIP, CPU_SS, CPU_ESP));
 }
 
-/*
- * 4.3.6. 特権レベル間のリターン操作
- *
- * 1. 特権チェックを実行する。
- * 2. CS レジスタと EIP レジスタにコール前の値をリストアする。
- * 3. RET 命令にオプション引き数の n がある場合は、パラメータをスタックから
- *    開放するため、n オペランドで指定されたバイト数だけスタック・ポインタを
- *    インクリメントする。コール・ゲート・ディスクリプタが、スタック間で
- *    1 つ以上のパラメータをコピーするよう指定している場合は、RET n 命令を
- *    使用して両スタックからパラメータを開放しなければならない。n オペランド
- *    には、各スタック壌でパラメータが占有するバイト数を指定する。
- *    リターン時に、プロセッサは各スタックに対して n だけ ESP をインクリメント
- *    し、これらのパラメータをスタックから効率よく削除する。
- * 4. SS レジスタと ESP レジスタに、コール前の値をリストアする。これで、
- *    コール元プロシージャのスタックへ切り替えられる。
- * 5. RET 命令にオプション引き数の n がある場合は、パラメータをスタックから
- *    開放するため、n オペランドで指定されたバイト数だけスタック・ポインタを
- *    インクリメントする(ステップ 3 の説明を参照)。
- * 6. コール元プロシージャの実行を再開する。
+/*---
+ * CALLfar_pm: code segment
  */
-void
-RETfar_pm(DWORD nbytes)
+static void
+CALLfar_pm_code_segment(const selector_t *cs_sel, UINT32 new_ip)
 {
-	selector_t ret_sel;
-	int rv;
-	DWORD new_ip;
-	WORD selector;
+	UINT32 sp;
+
+	VERBOSE(("CALLfar_pm: CODE-SEGMENT"));
 
-	VERBOSE(("RETfar_pm: EIP = 0x%08x, nbytes = %d", CPU_PREV_EIP, nbytes));
+	/* check privilege level */
+	if (!SEG_IS_CONFORMING_CODE(&cs_sel->desc)) {
+		VERBOSE(("CALLfar_pm: NON-CONFORMING-CODE-SEGMENT"));
+		/* 下巻 p.119 4.8.1.1. */
+		if (cs_sel->rpl > CPU_STAT_CPL) {
+			VERBOSE(("CALLfar_pm: RPL(%d) > CPL(%d)", cs_sel->rpl, CPU_STAT_CPL));
+			EXCEPTION(GP_EXCEPTION, cs_sel->idx);
+		}
+		if (cs_sel->desc.dpl != CPU_STAT_CPL) {
+			VERBOSE(("CALLfar_pm: DPL(%d) != CPL(%d)", cs_sel->desc.dpl, CPU_STAT_CPL));
+			EXCEPTION(GP_EXCEPTION, cs_sel->idx);
+		}
+	} else {
+		VERBOSE(("CALLfar_pm: CONFORMING-CODE-SEGMENT"));
+		/* 下巻 p.120 4.8.1.2. */
+		if (cs_sel->desc.dpl > CPU_STAT_CPL) {
+			VERBOSE(("CALLfar_pm: DPL(%d) > CPL(%d)", cs_sel->desc.dpl, CPU_STAT_CPL));
+			EXCEPTION(GP_EXCEPTION, cs_sel->idx);
+		}
+	}
+
+	/* not present */
+	if (selector_is_not_present(cs_sel)) {
+		VERBOSE(("CALLfar_pm: selector is not present"));
+		EXCEPTION(NP_EXCEPTION, cs_sel->idx);
+	}
 
+	if (CPU_STAT_SS32) {
+		sp = CPU_ESP;
+	} else {
+		sp = CPU_SP;
+	}
 	if (CPU_INST_OP32) {
-		CHECK_STACK_POP(&CPU_STAT_SREG(CPU_SS_INDEX), CPU_ESP, 8 + nbytes);
-		if (CPU_STAT_SS32) {
-			new_ip = cpu_vmemoryread_d(CPU_SS_INDEX, CPU_ESP);
-			selector = cpu_vmemoryread_d(CPU_SS_INDEX, CPU_ESP + 4);
-		} else {
-			new_ip = cpu_vmemoryread_d(CPU_SS_INDEX, CPU_SP);
-			selector = cpu_vmemoryread_d(CPU_SS_INDEX, CPU_SP + 4);
+		SS_PUSH_CHECK(sp, 8);
+
+		/* out of range */
+		if (new_ip > cs_sel->desc.u.seg.limit) {
+			VERBOSE(("CALLfar_pm: new_ip is out of range. new_ip = %08x, limit = %08x", new_ip, cs_sel->desc.u.seg.limit));
+			EXCEPTION(GP_EXCEPTION, 0);
 		}
+
+		PUSH0_32(CPU_CS);
+		PUSH0_32(CPU_EIP);
 	} else {
-		CHECK_STACK_POP(&CPU_STAT_SREG(CPU_SS_INDEX), CPU_ESP, 4 + nbytes);
-		if (CPU_STAT_SS32) {
-			new_ip = cpu_vmemoryread_w(CPU_SS_INDEX, CPU_ESP);
-			selector = cpu_vmemoryread_w(CPU_SS_INDEX, CPU_ESP + 2);
-		} else {
-			new_ip = cpu_vmemoryread_w(CPU_SS_INDEX, CPU_SP);
-			selector = cpu_vmemoryread_w(CPU_SS_INDEX, CPU_SP + 2);
+		SS_PUSH_CHECK(sp, 4);
+
+		/* out of range */
+		if (new_ip > cs_sel->desc.u.seg.limit) {
+			VERBOSE(("CALLfar_pm: new_ip is out of range. new_ip = %08x, limit = %08x", new_ip, cs_sel->desc.u.seg.limit));
+			EXCEPTION(GP_EXCEPTION, 0);
 		}
+
+		PUSH0_16(CPU_CS);
+		PUSH0_16(CPU_IP);
+	}
+
+	load_cs(cs_sel->selector, &cs_sel->desc, CPU_STAT_CPL);
+	CPU_EIP = new_ip;
+}
+
+/*---
+ * CALLfar_pm: call gate
+ */
+static void CALLfar_pm_call_gate_same_privilege(const selector_t *call_sel, selector_t *cs_sel);
+static void CALLfar_pm_call_gate_more_privilege(const selector_t *call_sel, selector_t *cs_sel);
+
+static void
+CALLfar_pm_call_gate(const selector_t *callgate_sel)
+{
+	selector_t cs_sel;
+	int rv;
+
+	VERBOSE(("CALLfar_pm: CALL-GATE"));
+
+	/* check privilege level */
+	if (callgate_sel->desc.dpl < CPU_STAT_CPL) {
+		VERBOSE(("CALLfar_pm: DPL(%d) < CPL(%d)", callgate_sel->desc.dpl, CPU_STAT_CPL));
+		EXCEPTION(GP_EXCEPTION, callgate_sel->idx);
+	}
+	if (callgate_sel->desc.dpl < callgate_sel->rpl) {
+		VERBOSE(("CALLfar_pm: DPL(%d) < CPL(%d)", callgate_sel->desc.dpl, callgate_sel->rpl));
+		EXCEPTION(GP_EXCEPTION, callgate_sel->idx);
+	}
+
+	/* not present */
+	if (selector_is_not_present(callgate_sel)) {
+		VERBOSE(("CALLfar_pm: selector is not present"));
+		EXCEPTION(NP_EXCEPTION, callgate_sel->idx);
 	}
 
-	rv = parse_selector(&ret_sel, selector);
+	/* parse code segment descriptor */
+	rv = parse_selector(&cs_sel, callgate_sel->desc.u.gate.selector);
 	if (rv < 0) {
-		EXCEPTION(GP_EXCEPTION, ret_sel.idx);
+		VERBOSE(("CALLfar_pm: parse_selector (selector = %04x, rv = %d)", callgate_sel->desc.u.gate.selector, rv));
+		EXCEPTION(GP_EXCEPTION, cs_sel.idx);
 	}
 
-	/* check code segment descriptor */
-	if (!ret_sel.desc.s || !ret_sel.desc.u.seg.c) {
-		EXCEPTION(GP_EXCEPTION, ret_sel.idx);
+	/* check segment type */
+	if (SEG_IS_SYSTEM(&cs_sel.desc)) {
+		VERBOSE(("CALLfar_pm: code segment is system segment"));
+		EXCEPTION(GP_EXCEPTION, cs_sel.idx);
+	}
+	if (SEG_IS_DATA(&cs_sel.desc)) {
+		VERBOSE(("CALLfar_pm: code segment is data segment"));
+		EXCEPTION(GP_EXCEPTION, cs_sel.idx);
 	}
 
 	/* check privilege level */
-	if (ret_sel.rpl < CPU_STAT_CPL
-	 || (ret_sel.desc.u.seg.ec && (ret_sel.desc.dpl > ret_sel.rpl))) {
-		EXCEPTION(GP_EXCEPTION, ret_sel.idx);
+	if (cs_sel.desc.dpl > CPU_STAT_CPL) {
+		VERBOSE(("CALLfar_pm: DPL(%d) > CPL(%d)", cs_sel.desc.dpl, CPU_STAT_CPL));
+		EXCEPTION(GP_EXCEPTION, cs_sel.idx);
 	}
 
 	/* not present */
-	if (selector_is_not_present(&ret_sel)) {
-		EXCEPTION(NP_EXCEPTION, ret_sel.idx);
+	if (selector_is_not_present(&cs_sel)) {
+		VERBOSE(("CALLfar_pm: selector is not present"));
+		EXCEPTION(NP_EXCEPTION, cs_sel.idx);
 	}
 
-	if (ret_sel.rpl > CPU_STAT_CPL) {
-		selector_t ss_sel;
-		selector_t temp_sel;
-		DWORD new_sp;
-		WORD new_ss;
-		int i;
+	/* out of range */
+	if (callgate_sel->desc.u.gate.offset > cs_sel.desc.u.seg.limit) {
+		VERBOSE(("CALLfar_pm: new_ip is out of range. new_ip = %08x, limit = %08x", callgate_sel->desc.u.gate.offset, cs_sel.desc.u.seg.limit));
+		EXCEPTION(GP_EXCEPTION, 0);
+	}
 
-		VERBOSE(("RETURN-OUTER-PRIVILEGE-LEVEL"));
+	if (!SEG_IS_CONFORMING_CODE(&cs_sel.desc) && (cs_sel.desc.dpl < CPU_STAT_CPL)) {
+	 	CALLfar_pm_call_gate_more_privilege(callgate_sel, &cs_sel);
+	} else {
+		CALLfar_pm_call_gate_same_privilege(callgate_sel, &cs_sel);
+	}
+}
 
-		if (CPU_INST_OP32) {
-			CHECK_STACK_POP(&CPU_STAT_SREG(CPU_SS_INDEX), CPU_ESP, 16 + nbytes);
-			if (CPU_STAT_SS32) {
-				new_sp = cpu_vmemoryread_d(CPU_SS_INDEX, CPU_ESP + 8 + nbytes);
-				new_ss = (WORD)cpu_vmemoryread_d(CPU_SS_INDEX, CPU_ESP + 8 + 4 + nbytes);
-			} else {
-				new_sp = cpu_vmemoryread_d(CPU_SS_INDEX, (WORD)(CPU_SP + 8 + nbytes));
-				new_ss = (WORD)cpu_vmemoryread_d(CPU_SS_INDEX, (WORD)(CPU_SP + 8 + 4 + nbytes));
-			}
-		} else {
-			CHECK_STACK_POP(&CPU_STAT_SREG(CPU_SS_INDEX), CPU_ESP, 8 + nbytes);
-			if (CPU_STAT_SS32) {
-				new_sp = cpu_vmemoryread_w(CPU_SS_INDEX, CPU_ESP + 4 + nbytes);
-				new_ss = cpu_vmemoryread_w(CPU_SS_INDEX, CPU_ESP + 4 + 2 + nbytes);
-			} else {
-				new_sp = cpu_vmemoryread_w(CPU_SS_INDEX, (WORD)(CPU_SP + 4 + nbytes));
-				new_ss = cpu_vmemoryread_w(CPU_SS_INDEX, (WORD)(CPU_SP + 4 + 2 + nbytes));
-			}
-		}
+/*---
+ * CALLfar_pm: call gate (SAME-PRIVILEGE)
+ */
+static void
+CALLfar_pm_call_gate_same_privilege(const selector_t *callgate_sel, selector_t *cs_sel)
+{
+	UINT32 sp;
 
-		rv = parse_selector(&ss_sel, new_ss);
-		if (rv < 0) {
-			EXCEPTION(GP_EXCEPTION, ss_sel.idx);
-		}
+	VERBOSE(("CALLfar_pm: SAME-PRIVILEGE"));
 
-		/* check stack segment descriptor */
-		/* check privilege level */
-		if ((ss_sel.rpl != ret_sel.rpl)
-		 || (ss_sel.desc.dpl != ret_sel.rpl)
-		 || !ss_sel.desc.s
-		 || !ss_sel.desc.u.seg.wr) {
-			EXCEPTION(GP_EXCEPTION, ss_sel.idx);
-		}
+	if (CPU_STAT_SS32) {
+		sp = CPU_ESP;
+	} else {
+		sp = CPU_SP;
+	}
+	if (callgate_sel->desc.type == CPU_SYSDESC_TYPE_CALL_32) {
+		SS_PUSH_CHECK(sp, 8);
+
+		PUSH0_32(CPU_CS);
+		PUSH0_32(CPU_EIP);
+	} else {
+		SS_PUSH_CHECK(sp, 4);
+
+		PUSH0_16(CPU_CS);
+		PUSH0_16(CPU_IP);
+	}
+
+	load_cs(cs_sel->selector, &cs_sel->desc, CPU_STAT_CPL);
+	CPU_EIP = callgate_sel->desc.u.gate.offset;
+}
+
+/*---
+ * CALLfar_pm: call gate (MORE-PRIVILEGE)
+ */
+static void
+CALLfar_pm_call_gate_more_privilege(const selector_t *callgate_sel, selector_t *cs_sel)
+{
+	UINT32 param[32];	/* copy param */
+	selector_t ss_sel;
+	UINT stacksize;
+	UINT32 old_eip, old_esp;
+	UINT32 new_esp;
+	UINT16 old_cs, old_ss;
+	UINT16 new_ss;
+	int param_count;
+	int i;
+	int rv;
+
+	VERBOSE(("CALLfar_pm: MORE-PRIVILEGE"));
+
+	/* save register */
+	old_cs = CPU_CS;
+	old_ss = CPU_SS;
+	old_eip = CPU_EIP;
+	old_esp = CPU_ESP;
+	if (!CPU_STAT_SS32) {
+		old_esp &= 0xffff;
+	}
+
+	/* get stack pointer from TSS */
+	get_stack_pointer_from_tss(cs_sel->desc.dpl, &new_ss, &new_esp);
+
+	/* parse stack segment descriptor */
+	rv = parse_selector(&ss_sel, new_ss);
+	if (rv < 0) {
+		VERBOSE(("CALLfar_pm: parse_selector (selector = %04x, rv = %d)", new_ss, rv));
+		EXCEPTION(TS_EXCEPTION, ss_sel.idx);
+	}
+
+	/* check privilege level */
+	if (ss_sel.rpl != cs_sel->desc.dpl) {
+		VERBOSE(("CALLfar_pm: selector RPL[SS](%d) != DPL[CS](%d)", ss_sel.rpl, cs_sel->desc.dpl));
+		EXCEPTION(TS_EXCEPTION, ss_sel.idx);
+	}
+	if (ss_sel.desc.dpl != cs_sel->desc.dpl) {
+		VERBOSE(("CALLfar_pm: descriptor DPL[SS](%d) != DPL[CS](%d)", ss_sel.desc.dpl, cs_sel->desc.dpl));
+		EXCEPTION(TS_EXCEPTION, ss_sel.idx);
+	}
+
+	/* stack segment must be writable data segment. */
+	if (SEG_IS_SYSTEM(&ss_sel.desc)) {
+		VERBOSE(("CALLfar_pm: stack segment is system segment"));
+		EXCEPTION(TS_EXCEPTION, ss_sel.idx);
+	}
+	if (SEG_IS_CODE(&ss_sel.desc)) {
+		VERBOSE(("CALLfar_pm: stack segment is code segment"));
+		EXCEPTION(TS_EXCEPTION, ss_sel.idx);
+	}
+	if (!SEG_IS_WRITABLE_DATA(&ss_sel.desc)) {
+		VERBOSE(("CALLfar_pm: stack segment is read-only data segment"));
+		EXCEPTION(TS_EXCEPTION, ss_sel.idx);
+	}
+
+	/* not present */
+	if (selector_is_not_present(&ss_sel)) {
+		VERBOSE(("CALLfar_pm: stack segment selector is not present"));
+		EXCEPTION(SS_EXCEPTION, ss_sel.idx);
+	}
+
+	param_count = callgate_sel->desc.u.gate.count;
+	VERBOSE(("CALLfar_pm: param_count = %d", param_count));
+
+	/* check stack size */
+	if (cs_sel->desc.d) {
+		stacksize = 16;
+	} else {
+		stacksize = 8;
+	}
+	if (callgate_sel->desc.type == CPU_SYSDESC_TYPE_CALL_32) {
+		stacksize += param_count * 4;
+	} else {
+		stacksize += param_count * 2;
+	}
+	cpu_stack_push_check(ss_sel.idx, &ss_sel.desc, new_esp, stacksize);
+
+	if (callgate_sel->desc.type == CPU_SYSDESC_TYPE_CALL_32) {
+		/* dump param */
+		for (i = 0; i < param_count; i++) {
+			param[i] = cpu_vmemoryread_d(CPU_SS_INDEX, old_esp + i * 4);
+			VERBOSE(("CALLfar_pm: get param[%d] = %08x", i, param[i]));
+		}
+
+		load_ss(ss_sel.selector, &ss_sel.desc, ss_sel.desc.dpl);
+		if (CPU_STAT_SS32) {
+			CPU_ESP = new_esp;
+		} else {
+			CPU_SP = (UINT16)new_esp;
+		}
+
+		load_cs(cs_sel->selector, &cs_sel->desc, cs_sel->desc.dpl);
+		CPU_EIP = callgate_sel->desc.u.gate.offset;
+
+		PUSH0_32(old_ss);
+		PUSH0_32(old_esp);
+
+		/* restore param */
+		for (i = param_count; i > 0; i--) {
+			PUSH0_32(param[i - 1]);
+			VERBOSE(("CALLfar_pm: set param[%d] = %08x", i - 1, param[i - 1]));
+		}
+
+		PUSH0_32(old_cs);
+		PUSH0_32(old_eip);
+	} else {
+		/* dump param */
+		for (i = 0; i < param_count; i++) {
+			param[i] = cpu_vmemoryread_w(CPU_SS_INDEX, old_esp + i * 2);
+			VERBOSE(("CALLfar_pm: get param[%d] = %04x", i, param[i]));
+		}
+
+		load_ss(ss_sel.selector, &ss_sel.desc, ss_sel.desc.dpl);
+		if (CPU_STAT_SS32) {
+			CPU_ESP = new_esp;
+		} else {
+			CPU_SP = (UINT16)new_esp;
+		}
+
+		load_cs(cs_sel->selector, &cs_sel->desc, cs_sel->desc.dpl);
+		CPU_EIP = callgate_sel->desc.u.gate.offset;
+
+		PUSH0_16(old_ss);
+		PUSH0_16(old_esp);
+
+		/* restore param */
+		for (i = param_count; i > 0; i--) {
+			PUSH0_16(param[i - 1]);
+			VERBOSE(("CALLfar_pm: set param[%d] = %04x", i - 1, param[i - 1]));
+		}
+
+		PUSH0_16(old_cs);
+		PUSH0_16(old_eip);
+	}
+}
+
+/*---
+ * CALLfar_pm: task gate
+ */
+static void
+CALLfar_pm_task_gate(selector_t *taskgate_sel)
+{
+	selector_t tss_sel;
+	int rv;
+
+	VERBOSE(("CALLfar_pm: TASK-GATE"));
+
+	/* check privilege level */
+	if (taskgate_sel->desc.dpl < CPU_STAT_CPL) {
+		VERBOSE(("CALLfar_pm: DPL(%d) < CPL(%d)", taskgate_sel->desc.dpl, CPU_STAT_CPL));
+		EXCEPTION(GP_EXCEPTION, taskgate_sel->idx);
+	}
+	if (taskgate_sel->desc.dpl < taskgate_sel->rpl) {
+		VERBOSE(("CALLfar_pm: DPL(%d) < CPL(%d)", taskgate_sel->desc.dpl, taskgate_sel->rpl));
+		EXCEPTION(GP_EXCEPTION, taskgate_sel->idx);
+	}
+
+	/* not present */
+	if (selector_is_not_present(taskgate_sel)) {
+		VERBOSE(("CALLfar_pm: selector is not present"));
+		EXCEPTION(NP_EXCEPTION, taskgate_sel->idx);
+	}
+
+	/* tss descriptor */
+	rv = parse_selector(&tss_sel, taskgate_sel->desc.u.gate.selector);
+	if (rv < 0 || tss_sel.ldt) {
+		VERBOSE(("CALLfar_pm: parse_selector (selector = %04x, rv = %d, %cDT)", tss_sel.selector, rv, tss_sel.ldt ? 'L' : 'G'));
+		EXCEPTION(GP_EXCEPTION, tss_sel.idx);
+	}
+
+	/* check descriptor type */
+	switch (tss_sel.desc.type) {
+	case CPU_SYSDESC_TYPE_TSS_16:
+	case CPU_SYSDESC_TYPE_TSS_32:
+		break;
+
+	case CPU_SYSDESC_TYPE_TSS_BUSY_16:
+	case CPU_SYSDESC_TYPE_TSS_BUSY_32:
+		VERBOSE(("CALLfar_pm: task is busy"));
+		/*FALLTHROUGH*/
+	default:
+		VERBOSE(("CALLfar_pm: invalid descriptor type (type = %d)", tss_sel.desc.type));
+		EXCEPTION(GP_EXCEPTION, tss_sel.idx);
+		break;
+	}
+
+	/* not present */
+	if (selector_is_not_present(&tss_sel)) {
+		VERBOSE(("CALLfar_pm: TSS selector is not present"));
+		EXCEPTION(NP_EXCEPTION, tss_sel.idx);
+	}
+
+	task_switch(&tss_sel, TASK_SWITCH_CALL);
+
+	/* out of range */
+	if (CPU_EIP > CPU_STAT_CS_LIMIT) {
+		VERBOSE(("JMPfar_pm: new_ip is out of range. new_ip = %08x, limit = %08x", CPU_EIP, CPU_STAT_CS_LIMIT));
+		EXCEPTION(GP_EXCEPTION, 0);
+	}
+}
+
+/*---
+ * CALLfar_pm: TSS
+ */
+static void
+CALLfar_pm_tss(selector_t *tss_sel)
+{
+
+	VERBOSE(("TASK-STATE-SEGMENT"));
+
+	/* check privilege level */
+	if (tss_sel->desc.dpl < CPU_STAT_CPL) {
+		VERBOSE(("CALLfar_pm: DPL(%d) < CPL(%d)", tss_sel->desc.dpl, CPU_STAT_CPL));
+		EXCEPTION(GP_EXCEPTION, tss_sel->idx);
+	}
+	if (tss_sel->desc.dpl < tss_sel->rpl) {
+		VERBOSE(("CALLfar_pm: DPL(%d) < CPL(%d)", tss_sel->desc.dpl, tss_sel->rpl));
+		EXCEPTION(GP_EXCEPTION, tss_sel->idx);
+	}
+
+	/* not present */
+	if (selector_is_not_present(tss_sel)) {
+		VERBOSE(("CALLfar_pm: TSS selector is not present"));
+		EXCEPTION(NP_EXCEPTION, tss_sel->idx);
+	}
+
+	task_switch(tss_sel, TASK_SWITCH_CALL);
+
+	/* out of range */
+	if (CPU_EIP > CPU_STAT_CS_LIMIT) {
+		VERBOSE(("JMPfar_pm: new_ip is out of range. new_ip = %08x, limit = %08x", CPU_EIP, CPU_STAT_CS_LIMIT));
+		EXCEPTION(GP_EXCEPTION, 0);
+	}
+}
+
+
+/*------------------------------------------------------------------------------
+ * RETfar_pm
+ */
+
+void
+RETfar_pm(UINT nbytes)
+{
+	selector_t cs_sel, ss_sel, temp_sel;
+	descriptor_t *sdp;
+	UINT32 sp;
+	UINT32 new_ip, new_sp;
+	UINT16 new_cs, new_ss;
+	int rv;
+	int i;
+
+	VERBOSE(("RETfar_pm: old EIP = %04x:%08x, ESP = %04x:%08x, nbytes = %d", CPU_CS, CPU_PREV_EIP, CPU_SS, CPU_ESP, nbytes));
+
+	if (CPU_STAT_SS32) {
+		sp = CPU_ESP;
+	} else {
+		sp = CPU_SP;
+	}
+	if (CPU_INST_OP32) {
+		SS_POP_CHECK(sp, nbytes + 8);
+		new_ip = cpu_vmemoryread_d(CPU_SS_INDEX, sp);
+		new_cs = cpu_vmemoryread_w(CPU_SS_INDEX, sp + 4);
+	} else {
+		SS_POP_CHECK(sp, nbytes + 4);
+		new_ip = cpu_vmemoryread_w(CPU_SS_INDEX, sp);
+		new_cs = cpu_vmemoryread_w(CPU_SS_INDEX, sp + 2);
+	}
+
+	rv = parse_selector(&cs_sel, new_cs);
+	if (rv < 0) {
+		VERBOSE(("RETfar_pm: parse_selector (selector = %04x, rv = %d)", cs_sel.selector, rv));
+		EXCEPTION(GP_EXCEPTION, cs_sel.idx);
+	}
+
+	/* check segment type */
+	if (SEG_IS_SYSTEM(&cs_sel.desc)) {
+		VERBOSE(("RETfar_pm: return to system segment"));
+		EXCEPTION(GP_EXCEPTION, cs_sel.idx);
+	}
+	if (SEG_IS_DATA(&cs_sel.desc)) {
+		VERBOSE(("RETfar_pm: return to data segment"));
+		EXCEPTION(GP_EXCEPTION, cs_sel.idx);
+	}
+
+	/* check privilege level */
+	if (cs_sel.rpl < CPU_STAT_CPL) {
+		VERBOSE(("RETfar_pm: RPL(%d) < CPL(%d)", cs_sel.rpl, CPU_STAT_CPL));
+		EXCEPTION(GP_EXCEPTION, cs_sel.idx);
+	}
+	if (!SEG_IS_CONFORMING_CODE(&cs_sel.desc) && (cs_sel.desc.dpl > cs_sel.rpl)) {
+		VERBOSE(("RETfar_pm: NON-COMFORMING-CODE-SEGMENT and DPL(%d) > RPL(%d)", cs_sel.desc.dpl, cs_sel.rpl));
+		EXCEPTION(GP_EXCEPTION, cs_sel.idx);
+	}
+
+	/* not present */
+	if (selector_is_not_present(&cs_sel)) {
+		VERBOSE(("RETfar_pm: returned code segment is not present"));
+		EXCEPTION(NP_EXCEPTION, cs_sel.idx);
+	}
+
+	if (cs_sel.rpl == CPU_STAT_CPL) {
+		VERBOSE(("RETfar_pm: RETURN-TO-SAME-PRIVILEGE-LEVEL"));
+
+		/* check code segment limit */
+		if (new_ip > cs_sel.desc.u.seg.limit) {
+			VERBOSE(("RETfar_pm: new_ip is out of range. new_ip = %08x, limit = %08x", new_ip, cs_sel.desc.u.seg.limit));
+			EXCEPTION(GP_EXCEPTION, 0);
+		}
+
+		VERBOSE(("RETfar_pm: new_ip = %08x, new_cs = %04x", new_ip, cs_sel.selector));
+
+		if (CPU_INST_OP32) {
+			nbytes += 8;
+		} else {
+			nbytes += 4;
+		}
+		if (CPU_STAT_SS32) {
+			CPU_ESP += nbytes;
+		} else {
+			CPU_SP += (UINT16)nbytes;
+		}
+
+		load_cs(cs_sel.selector, &cs_sel.desc, CPU_STAT_CPL);
+		CPU_EIP = new_ip;
+	} else {
+		VERBOSE(("RETfar_pm: RETURN-OUTER-PRIVILEGE-LEVEL"));
+
+		if (CPU_INST_OP32) {
+			SS_POP_CHECK(sp, 8 + 8 + nbytes);
+			new_sp = cpu_vmemoryread_d(CPU_SS_INDEX, sp + 8 + nbytes);
+			new_ss = cpu_vmemoryread_w(CPU_SS_INDEX, sp + 8 + nbytes + 4);
+		} else {
+			SS_POP_CHECK(sp, 4 + 4 + nbytes);
+			new_sp = cpu_vmemoryread_w(CPU_SS_INDEX, sp + 4 + nbytes);
+			new_ss = cpu_vmemoryread_w(CPU_SS_INDEX, sp + 4 + nbytes + 2);
+		}
+
+		rv = parse_selector(&ss_sel, new_ss);
+		if (rv < 0) {
+			VERBOSE(("RETfar_pm: parse_selector (selector = %04x, rv = %d)", ss_sel.selector, rv));
+			EXCEPTION(GP_EXCEPTION, (rv == -2) ? 0 : ss_sel.idx);
+		}
+
+		/* stack segment must be writable data segment. */
+		if (SEG_IS_SYSTEM(&ss_sel.desc)) {
+			VERBOSE(("RETfar_pm: stack segment is system segment"));
+			EXCEPTION(GP_EXCEPTION, cs_sel.idx);
+		}
+		if (SEG_IS_CODE(&ss_sel.desc)) {
+			VERBOSE(("RETfar_pm: stack segment is code segment"));
+			EXCEPTION(GP_EXCEPTION, cs_sel.idx);
+		}
+		if (!SEG_IS_WRITABLE_DATA(&ss_sel.desc)) {
+			VERBOSE(("RETfar_pm: stack segment is read-only data segment"));
+			EXCEPTION(GP_EXCEPTION, cs_sel.idx);
+		}
+
+		/* check privilege level */
+		if (ss_sel.rpl != cs_sel.rpl) {
+			VERBOSE(("RETfar_pm: selector RPL[SS](%d) != RPL[CS](%d)", ss_sel.rpl, cs_sel.rpl));
+			EXCEPTION(GP_EXCEPTION, cs_sel.idx);
+		}
+		if (ss_sel.desc.dpl != cs_sel.rpl) {
+			VERBOSE(("RETfar_pm: descriptor DPL[SS](%d) != RPL[CS](%d)", ss_sel.desc.dpl, cs_sel.rpl));
+			EXCEPTION(GP_EXCEPTION, cs_sel.idx);
+		}
 
 		/* not present */
 		if (selector_is_not_present(&ss_sel)) {
+			VERBOSE(("RETfar_pm: stack segment is not present"));
 			EXCEPTION(SS_EXCEPTION, ss_sel.idx);
 		}
 
 		/* check code segment limit */
-		if (new_ip > ret_sel.desc.u.seg.limit) {
+		if (new_ip > cs_sel.desc.u.seg.limit) {
+			VERBOSE(("RETfar_pm: new_ip is out of range. new_ip = %08x, limit = %08x", new_ip, cs_sel.desc.u.seg.limit));
 			EXCEPTION(GP_EXCEPTION, 0);
 		}
 
-		/* set new register */
-		load_cs(ret_sel.selector, &ret_sel.desc, ret_sel.rpl);
-		SET_EIP(new_ip);
-		load_ss(ss_sel.selector, &ss_sel.desc, ret_sel.rpl);
-		CPU_ESP = new_sp;
+		VERBOSE(("RETfar_pm: new_ip = %08x, new_cs = %04x", new_ip, cs_sel.selector));
+		VERBOSE(("RETfar_pm: new_sp = %08x, new_ss = %04x", new_sp, ss_sel.selector));
+
+		load_ss(ss_sel.selector, &ss_sel.desc, cs_sel.rpl);
+		if (CPU_STAT_SS32) {
+			CPU_ESP = new_sp + nbytes;
+		} else {
+			CPU_SP = (UINT16)(new_sp + nbytes);
+		}
+
+		load_cs(cs_sel.selector, &cs_sel.desc, cs_sel.rpl);
+		CPU_EIP = new_ip;
 
 		/* check segment register */
 		for (i = 0; i < CPU_SEGREG_NUM; i++) {
-			if (i == CPU_CS_INDEX || i == CPU_SS_INDEX)
+			if (i == CPU_SS_INDEX || i == CPU_CS_INDEX)
 				continue;
 
+			sdp = &CPU_STAT_SREG(i);
+			if ((SEG_IS_DATA(sdp) || !SEG_IS_CONFORMING_CODE(sdp))
+			 && (CPU_STAT_CPL > sdp->dpl)) {
+				/* current segment descriptor is invalid */
+				CPU_REGS_SREG(i) = 0;
+				segdesc_clear(sdp);
+				continue;
+			}
+
+			/* Reload segment descriptor */
 			rv = parse_selector(&temp_sel, CPU_REGS_SREG(i));
 			if (rv < 0) {
+				/* segment register is invalid */
 				CPU_REGS_SREG(i) = 0;
-				CPU_STAT_SREG(i).valid = 0;
+				segdesc_clear(sdp);
 				continue;
 			}
 
-			/* check privilege level */
-			if (!temp_sel.desc.s
-			 || (temp_sel.desc.u.seg.c && temp_sel.desc.u.seg.wr)
-			 || ((!temp_sel.desc.u.seg.c || !temp_sel.desc.u.seg.ec)
-			   && ((temp_sel.desc.dpl < CPU_STAT_CPL) || (temp_sel.desc.dpl < temp_sel.rpl)))) {
+			/*
+			 * - system segment
+			 * - execute-only code segment
+			 * - data or conforming code segment && CPL > DPL
+			 */
+			if (SEG_IS_SYSTEM(&temp_sel.desc)
+			 || (SEG_IS_CODE(&temp_sel.desc)
+			     && !SEG_IS_READABLE_CODE(&temp_sel.desc))
+			 || ((SEG_IS_DATA(&temp_sel.desc)
+			       || !SEG_IS_CONFORMING_CODE(&temp_sel.desc))
+			     && (CPU_STAT_CPL > temp_sel.desc.dpl))) {
+				/* segment descriptor is invalid */
 				CPU_REGS_SREG(i) = 0;
-				CPU_STAT_SREG(i).valid = 0;
-				continue;
+				segdesc_clear(sdp);
 			}
 		}
-		CPU_ESP += nbytes;
-	} else {
-		VERBOSE(("RETURN-TO-SAME-PRIVILEGE-LEVEL"));
+	}
+
+	VERBOSE(("RETfar_pm: new EIP = %04x:%08x, ESP = %04x:%08x", CPU_CS, CPU_EIP, CPU_SS, CPU_ESP));
+}
+
 
+/*------------------------------------------------------------------------------
+ * IRET_pm
+ */
+static void IRET_pm_nested_task(void);
+static void IRET_pm_protected_mode_return(UINT16 new_cs, UINT32 new_ip, UINT32 new_flags);
+static void IRET_pm_protected_mode_return_same_privilege(const selector_t *cs_sel, UINT32 new_ip, UINT32 new_flags);
+static void IRET_pm_protected_mode_return_outer_privilege(const selector_t *cs_sel, UINT32 new_ip, UINT32 new_flags);
+static void IRET_pm_return_to_vm86(UINT16 new_cs, UINT32 new_ip, UINT32 new_flags);
+static void IRET_pm_return_from_vm86(UINT16 new_cs, UINT32 new_ip, UINT32 new_flags);
+
+void
+IRET_pm(void)
+{
+	UINT32 sp;
+	UINT32 new_ip, new_flags;
+	UINT16 new_cs;
+
+	VERBOSE(("IRET_pm: old EIP = %04x:%08x, ESP = %04x:%08x", CPU_CS, CPU_PREV_EIP, CPU_SS, CPU_ESP));
+
+	if (!(CPU_EFLAG & VM_FLAG) && (CPU_EFLAG & NT_FLAG)) {
+		/* TASK-RETURN: PE=1, VM=0, NT=1 */
+		IRET_pm_nested_task();
+	} else {
+		if (CPU_STAT_SS32) {
+			sp = CPU_ESP;
+		} else {
+			sp = CPU_SP;
+		}
 		if (CPU_INST_OP32) {
-			if (new_ip > ret_sel.desc.u.seg.limit) {
-				EXCEPTION(GP_EXCEPTION, 0);
-			}
-			POP0_32(CPU_EIP);
-			POP0_32(CPU_CS);
+			SS_POP_CHECK(sp, 12);
+			new_ip = cpu_vmemoryread_d(CPU_SS_INDEX, sp);
+			new_cs = cpu_vmemoryread_w(CPU_SS_INDEX, sp + 4);
+			new_flags = cpu_vmemoryread_d(CPU_SS_INDEX, sp + 8);
 		} else {
-			new_ip &= 0xffff;
-			if (new_ip > ret_sel.desc.u.seg.limit) {
-				EXCEPTION(GP_EXCEPTION, 0);
-			}
-			POP0_16(CPU_EIP);
-			POP0_16(CPU_CS);
+			SS_POP_CHECK(sp, 6);
+			new_ip = cpu_vmemoryread_w(CPU_SS_INDEX, sp);
+			new_cs = cpu_vmemoryread_w(CPU_SS_INDEX, sp + 2);
+			new_flags = cpu_vmemoryread_w(CPU_SS_INDEX, sp + 4);
+		}
+
+		VERBOSE(("IRET_pm: new_ip = %08x, new_cs = %04x, new_eflags = %08x", new_ip, new_cs, new_flags));
+
+		if (CPU_EFLAG & VM_FLAG) {
+			/* RETURN-FROM-VIRTUAL-8086-MODE */
+			IRET_pm_return_from_vm86(new_cs, new_ip, new_flags);
+		} else if ((new_flags & VM_FLAG) && CPU_STAT_CPL == 0) {
+			/* RETURN-TO-VIRTUAL-8086-MODE */
+			IRET_pm_return_to_vm86(new_cs, new_ip, new_flags);
+		} else {
+			/* PROTECTED-MODE-RETURN */
+			IRET_pm_protected_mode_return(new_cs, new_ip, new_flags);
 		}
-		load_cs(ret_sel.selector, &ret_sel.desc, CPU_STAT_CPL);
-		SET_EIP(new_ip);
-		CPU_ESP += nbytes;
 	}
+
+	VERBOSE(("IRET_pm: new EIP = %04x:%08x, ESP = %04x:%08x", CPU_CS, CPU_EIP, CPU_SS, CPU_ESP));
 }
 
-void
-IRET_pm()
+/*---
+ * IRET_pm: NT_FLAG
+ */
+static void
+IRET_pm_nested_task(void)
 {
-	selector_t iret_sel;
+	selector_t tss_sel;
+	UINT16 new_tss;
 	int rv;
-	DWORD new_ip, new_flags;
-	WORD new_cs;
 
-	VERBOSE(("IRET_pm: EIP = 0x%08x", CPU_PREV_EIP));
+	VERBOSE(("IRET_pm: TASK-RETURN: PE=1, VM=0, NT=1"));
 
-	if (CPU_STAT_VM86) {
-		/* RETURN-FROM-VIRTUAL-8086-MODE */
-		VERBOSE(("Virtual-8086 mode: PE=1, VM=1"));
-		VERBOSE(("Processor is in virtual-8086 mode when IRET is executed and stays in virtual-8086 mode"));
-
-		if (CPU_STAT_IOPL == CPU_IOPL3) {
-			VERBOSE(("Virtual mode: PE=1, VM=1, IOPL=3"));
-			if (CPU_INST_OP32) {
-				CHECK_STACK_POP(&CPU_STAT_SREG(CPU_SS_INDEX), CPU_ESP, 12);
-				POP0_32(new_ip);
-				POP0_32(new_cs);
-				POP0_32(new_flags);
-
-				set_eflags(new_flags, I_FLAG|RF_FLAG);
-			} else {
-				CHECK_STACK_POP(&CPU_STAT_SREG(CPU_SS_INDEX), CPU_ESP, 6);
-				POP0_16(new_ip);
-				POP0_16(new_cs);
-				POP0_16(new_flags);
+	new_tss = get_backlink_selector_from_tss();
 
-				set_flags(new_flags, I_FLAG);
-			}
-			CPU_SET_SEGREG(CPU_CS_INDEX, new_cs);
-			SET_EIP(new_ip);
-			return;
-		}
-		VERBOSE(("trap to virtual-8086 monitor: PE=1, VM=1, IOPL<3"));
+	rv = parse_selector(&tss_sel, new_tss);
+	if (rv < 0 || tss_sel.ldt) {
+		VERBOSE(("IRET_pm: parse_selector (selector = %04x, rv = %d, %cDT)", tss_sel.selector, rv, tss_sel.ldt ? 'L' : 'G'));
+		EXCEPTION(GP_EXCEPTION, tss_sel.idx);
+	}
+
+	/* check system segment */
+	if (!SEG_IS_SYSTEM(&tss_sel.desc)) {
+		VERBOSE(("IRET_pm: task segment is %s segment", tss_sel.desc.u.seg.c ? "code" : "data"));
+		EXCEPTION(GP_EXCEPTION, tss_sel.idx);
+	}
+
+	switch (tss_sel.desc.type) {
+	case CPU_SYSDESC_TYPE_TSS_BUSY_16:
+	case CPU_SYSDESC_TYPE_TSS_BUSY_32:
+		break;
+
+	case CPU_SYSDESC_TYPE_TSS_16:
+	case CPU_SYSDESC_TYPE_TSS_32:
+		VERBOSE(("IRET_pm: task is not busy"));
+		/*FALLTHROUGH*/
+	default:
+		VERBOSE(("IRET_pm: invalid descriptor type (type = %d)", tss_sel.desc.type));
+		EXCEPTION(GP_EXCEPTION, tss_sel.idx);
+		break;
+	}
+
+	/* not present */
+	if (selector_is_not_present(&tss_sel)) {
+		VERBOSE(("IRET_pm: tss segment is not present"));
+		EXCEPTION(NP_EXCEPTION, tss_sel.idx);
+	}
+
+	task_switch(&tss_sel, TASK_SWITCH_IRET);
+
+	/* out of range */
+	if (CPU_EIP > CPU_STAT_CS_LIMIT) {
+		VERBOSE(("JMPfar_pm: new_ip is out of range. new_ip = %08x, limit = %08x", CPU_EIP, CPU_STAT_CS_LIMIT));
 		EXCEPTION(GP_EXCEPTION, 0);
-	} else if (CPU_EFLAG & NT_FLAG) {
-		VERBOSE(("TASK-RETURN: PE=1, VM=0, NT=1"));
+	}
+}
 
-		new_cs = get_link_selector_from_tss();
-		rv = parse_selector(&iret_sel, new_cs);
-		if (rv < 0 || iret_sel.ldt) {
-			EXCEPTION(GP_EXCEPTION, iret_sel.idx);
-		}
+/*---
+ * IRET_pm: PROTECTED-MODE-RETURN
+ */
+static void
+IRET_pm_protected_mode_return(UINT16 new_cs, UINT32 new_ip, UINT32 new_flags)
+{
+	selector_t cs_sel;
+	int rv;
 
-		/* check system segment */
-		if (iret_sel.desc.s) {
-			EXCEPTION(GP_EXCEPTION, iret_sel.idx);
-		}
-		switch (iret_sel.desc.type) {
-		case CPU_SYSDESC_TYPE_TSS_BUSY_16:
-		case CPU_SYSDESC_TYPE_TSS_BUSY_32:
-			break;
+	/* PROTECTED-MODE-RETURN */
+	VERBOSE(("IRET_pm: PE=1, VM=0 in flags image"));
 
-		case CPU_SYSDESC_TYPE_TSS_16:
-		case CPU_SYSDESC_TYPE_TSS_32:
-			VERBOSE(("IRET_pm: task is not busy"));
-			/*FALLTHROUGH*/
-		default:
-			EXCEPTION(GP_EXCEPTION, iret_sel.idx);
-			break;
-		}
+	rv = parse_selector(&cs_sel, new_cs);
+	if (rv < 0) {
+		VERBOSE(("IRET_pm: parse_selector (selector = %04x, rv = %d)", cs_sel.selector, rv));
+		EXCEPTION(GP_EXCEPTION, cs_sel.idx);
+	}
 
-		/* not present */
-		if (selector_is_not_present(&iret_sel)) {
-			EXCEPTION(NP_EXCEPTION, iret_sel.idx);
-		}
+	/* check code segment descriptor */
+	if (SEG_IS_SYSTEM(&cs_sel.desc)) {
+		VERBOSE(("IRET_pm: return code segment is system segment"));
+		EXCEPTION(GP_EXCEPTION, cs_sel.idx);
+	}
+	if (SEG_IS_DATA(&cs_sel.desc)) {
+		VERBOSE(("IRET_pm: return code segment is data segment"));
+		EXCEPTION(GP_EXCEPTION, cs_sel.idx);
+	}
 
-		task_switch(&iret_sel, TASK_SWITCH_IRET);
+	/* check privilege level */
+	if (cs_sel.rpl < CPU_STAT_CPL) {
+		VERBOSE(("IRET_pm: RPL(%d) < CPL(%d)", cs_sel.rpl, CPU_STAT_CPL));
+		EXCEPTION(GP_EXCEPTION, cs_sel.idx);
+	}
+	if (SEG_IS_CONFORMING_CODE(&cs_sel.desc) && (cs_sel.desc.dpl > cs_sel.rpl)) {
+		VERBOSE(("IRET_pm: CONFORMING-CODE-SEGMENT and DPL(%d) > RPL(%d)", cs_sel.desc.dpl, cs_sel.rpl));
+		EXCEPTION(GP_EXCEPTION, cs_sel.idx);
+	}
 
-		/* out of range */
-		if (CPU_EIP > CPU_STAT_CS_LIMIT) {
-			EXCEPTION(GP_EXCEPTION, 0);
+	/* not present */
+	if (selector_is_not_present(&cs_sel)) {
+		VERBOSE(("IRET_pm: code segment is not present"));
+		EXCEPTION(NP_EXCEPTION, cs_sel.idx);
+	}
+
+	if (cs_sel.rpl > CPU_STAT_CPL) {
+		IRET_pm_protected_mode_return_outer_privilege(&cs_sel, new_ip, new_flags);
+	} else {
+		IRET_pm_protected_mode_return_same_privilege(&cs_sel, new_ip, new_flags);
+	}
+}
+
+/*---
+ * IRET_pm: SAME-PRIVILEGE
+ */
+static void
+IRET_pm_protected_mode_return_same_privilege(const selector_t *cs_sel, UINT32 new_ip, UINT32 new_flags)
+{
+	UINT32 mask;
+	UINT stacksize;
+
+	VERBOSE(("IRET_pm: RETURN-TO-SAME-PRIVILEGE-LEVEL"));
+
+	/* check code segment limit */
+	if (new_ip > cs_sel->desc.u.seg.limit) {
+		VERBOSE(("IRET_pm: new_ip is out of range. new_ip = %08x, limit = %08x", new_ip, cs_sel->desc.u.seg.limit));
+		EXCEPTION(GP_EXCEPTION, 0);
+	}
+
+	mask = 0;
+	if (CPU_INST_OP32)
+		mask |= RF_FLAG;
+	if (CPU_STAT_CPL <= CPU_STAT_IOPL)
+		mask |= I_FLAG;
+	if (CPU_STAT_CPL == 0) {
+		mask |= IOPL_FLAG;
+		if (CPU_INST_OP32) {
+			mask |= VM_FLAG|VIF_FLAG|VIP_FLAG;
 		}
+	}
+
+	if (CPU_INST_OP32) {
+		stacksize = 12;
 	} else {
+		stacksize = 6;
+	}
+
+	/* set new register */
+	load_cs(cs_sel->selector, &cs_sel->desc, CPU_STAT_CPL);
+	CPU_EIP = new_ip;
+
+	if (CPU_STAT_SS32) {
+		CPU_ESP += stacksize;
+	} else {
+		CPU_SP += (UINT16)stacksize;
+	}
+
+	set_eflags(new_flags, mask);
+}
+
+/*---
+ * IRET_pm: OUTER-PRIVILEGE
+ */
+static void
+IRET_pm_protected_mode_return_outer_privilege(const selector_t *cs_sel, UINT32 new_ip, UINT32 new_flags)
+{
+	descriptor_t *sdp;
+	selector_t ss_sel;
+	UINT32 mask;
+	UINT32 sp;
+	UINT32 new_sp;
+	UINT16 new_ss;
+	int rv;
+	int i;
+
+	VERBOSE(("IRET_pm: RETURN-OUTER-PRIVILEGE-LEVEL"));
+
+	if (CPU_STAT_SS32) {
+		sp = CPU_ESP;
+	} else {
+		sp = CPU_SP;
+	}
+	if (CPU_INST_OP32) {
+		SS_POP_CHECK(sp, 20);
+		new_sp = cpu_vmemoryread_d(CPU_SS_INDEX, sp + 12);
+		new_ss = cpu_vmemoryread_w(CPU_SS_INDEX, sp + 16);
+	} else {
+		SS_POP_CHECK(sp, 10);
+		new_sp = cpu_vmemoryread_w(CPU_SS_INDEX, sp + 6);
+		new_ss = cpu_vmemoryread_w(CPU_SS_INDEX, sp + 8);
+	}
+	VERBOSE(("IRET_pm: new_sp = 0x%08x, new_ss = 0x%04x", new_sp, new_ss));
+
+	rv = parse_selector(&ss_sel, new_ss);
+	if (rv < 0) {
+		VERBOSE(("IRET_pm: parse_selector (selector = %04x, rv = %d)", ss_sel.selector, rv));
+		EXCEPTION(GP_EXCEPTION, (rv == -2) ? 0 : ss_sel.idx);
+	}
+
+	/* check privilege level */
+	if (ss_sel.rpl != cs_sel->rpl) {
+		VERBOSE(("IRET_pm: selector RPL[SS](%d) != RPL[CS](%d)", ss_sel.rpl, cs_sel->rpl));
+		EXCEPTION(GP_EXCEPTION, ss_sel.idx);
+	}
+#if 0
+	if (ss_sel.desc.dpl != cs_sel->rpl) {
+		VERBOSE(("IRET_pm: segment DPL[SS](%d) != RPL[CS](%d)", ss_sel.desc.dpl, cs_sel->rpl));
+		EXCEPTION(GP_EXCEPTION, ss_sel.idx);
+	}
+	if (ss_sel.desc.rpl != cs_sel->rpl) {
+		VERBOSE(("IRET_pm: segment RPL[SS](%d) != RPL[CS](%d)", ss_sel.desc.rpl, cs_sel->rpl));
+		EXCEPTION(GP_EXCEPTION, ss_sel.idx);
+	}
+#endif
+
+	/* stack segment must be writable data segment. */
+	if (SEG_IS_SYSTEM(&ss_sel.desc)) {
+		VERBOSE(("IRET_pm: stack segment is system segment"));
+		EXCEPTION(GP_EXCEPTION, ss_sel.idx);
+	}
+	if (SEG_IS_CODE(&ss_sel.desc)) {
+		VERBOSE(("IRET_pm: stack segment is code segment"));
+		EXCEPTION(GP_EXCEPTION, ss_sel.idx);
+	}
+	if (!SEG_IS_WRITABLE_DATA(&ss_sel.desc)) {
+		VERBOSE(("IRET_pm: stack segment is read-only data segment"));
+		EXCEPTION(GP_EXCEPTION, ss_sel.idx);
+	}
+
+	/* not present */
+	if (selector_is_not_present(&ss_sel)) {
+		VERBOSE(("IRET_pm: stack segment is not present"));
+		EXCEPTION(SS_EXCEPTION, ss_sel.idx);
+	}
+
+	/* check code segment limit */
+	if (new_ip > cs_sel->desc.u.seg.limit) {
+		VERBOSE(("IRET_pm: new_ip is out of range. new_ip = %08x, limit = %08x", new_ip, cs_sel->desc.u.seg.limit));
+		EXCEPTION(GP_EXCEPTION, 0);
+	}
+
+	mask = 0;
+	if (CPU_INST_OP32)
+		mask |= RF_FLAG;
+	if (CPU_STAT_CPL <= CPU_STAT_IOPL)
+		mask |= I_FLAG;
+	if (CPU_STAT_CPL == 0) {
+		mask |= IOPL_FLAG;
 		if (CPU_INST_OP32) {
-			CHECK_STACK_POP(&CPU_STAT_SREG(CPU_SS_INDEX), CPU_ESP, 12);
-			POP0_32(new_ip);
-			POP0_32(new_cs);
-			POP0_32(new_flags);
-		} else {
-			CHECK_STACK_POP(&CPU_STAT_SREG(CPU_SS_INDEX), CPU_ESP, 6);
-			POP0_16(new_ip);
-			POP0_16(new_cs);
-			POP0_16(new_flags);
+			mask |= VM_FLAG|VIF_FLAG|VIP_FLAG;
 		}
+	}
 
-		if ((CPU_STAT_CPL == 0) && (new_flags & VM_FLAG)) {
-			/* RETURN-TO-VIRTUAL-8086-MODE */
-			descriptor_t sd;
-			DWORD new_sp;
-			WORD segsel[CPU_SEGREG_NUM];
-			int i;
-
-			VERBOSE(("Interrupt procedure was in virtual-8086 mode: PE=1, VM=1 in flags image"));
-
-			CHECK_STACK_POP(&CPU_STAT_SREG(CPU_SS_INDEX), CPU_ESP, 24);
-
-			segsel[CPU_CS_INDEX] = new_cs;
-			POP0_32(new_sp);
-			POP0_32(segsel[CPU_SS_INDEX]);
-			POP0_32(segsel[CPU_ES_INDEX]);
-			POP0_32(segsel[CPU_DS_INDEX]);
-			POP0_32(segsel[CPU_FS_INDEX]);
-			POP0_32(segsel[CPU_GS_INDEX]);
-
-			for (i = 0; i < CPU_SEGREG_NUM; i++) {
-				CPU_REGS_SREG(i) = segsel[i];
-				sd.u.seg.limit = 0xffff;
-				CPU_SET_SEGDESC_DEFAULT(&sd, i, segsel[i]);
-				sd.dpl = 3;
-				CPU_STAT_SREG(i) = sd;
-			}
-			CPU_ESP = new_sp;
-			SET_EIP(new_ip & 0xffff);
+	/* set new register */
+	load_cs(cs_sel->selector, &cs_sel->desc, cs_sel->rpl);
+	CPU_EIP = new_ip;
 
-			set_eflags(new_flags, IOPL_FLAG|RF_FLAG);
-		} else {
-			DWORD mask;
+	load_ss(ss_sel.selector, &ss_sel.desc, cs_sel->rpl);
+	if (CPU_STAT_SS32) {
+		CPU_ESP = new_sp;
+	} else {
+		CPU_SP = (UINT16)new_sp;
+	}
 
-			/* PROTECTED-MODE-RETURN */
-			VERBOSE(("PE=1, VM=0 in flags image"));
+	set_eflags(new_flags, mask);
 
-			rv = parse_selector(&iret_sel, new_cs);
-			if (rv < 0) {
-				EXCEPTION(GP_EXCEPTION, iret_sel.idx);
+	/* check segment register */
+	for (i = 0; i < CPU_SEGREG_NUM; i++) {
+		if ((i != CPU_CS_INDEX) && (i != CPU_SS_INDEX)) {
+			sdp = &CPU_STAT_SREG(i);
+			if ((SEG_IS_DATA(sdp) || !SEG_IS_CONFORMING_CODE(sdp))
+			 && (sdp->dpl < CPU_STAT_CPL)) {
+				/* segment register is invalid */
+				CPU_REGS_SREG(i) = 0;
+				segdesc_clear(sdp);
 			}
+		}
+	}
+}
 
-			/* check code segment descriptor */
-			if (!iret_sel.desc.s || !iret_sel.desc.u.seg.c) {
-				EXCEPTION(GP_EXCEPTION, iret_sel.idx);
-			}
+/*---
+ * IRET_pm: new_flags & VM_FLAG
+ */
+static void
+IRET_pm_return_to_vm86(UINT16 new_cs, UINT32 new_ip, UINT32 new_flags)
+{
+	UINT16 segsel[CPU_SEGREG_NUM];
+	UINT32 sp;
+	UINT32 new_sp;
+	int i;
 
-			/* check privilege level */
-			if ((iret_sel.rpl < CPU_STAT_CPL)
-			 || (iret_sel.desc.u.seg.ec && (iret_sel.desc.dpl > iret_sel.rpl))) {
-				EXCEPTION(GP_EXCEPTION, iret_sel.idx);
-			}
+	VERBOSE(("IRET_pm: Interrupt procedure was in virtual-8086 mode: PE=1, VM=1 in flags image"));
 
-			/* not present */
-			if (selector_is_not_present(&iret_sel)) {
-				EXCEPTION(NP_EXCEPTION, iret_sel.idx);
-			}
+	if (!CPU_INST_OP32) {
+		ia32_panic("IRET_pm: 16bit mode");
+	}
 
-			if (iret_sel.rpl > CPU_STAT_CPL) {
-				/* RETURN-OUTER-PRIVILEGE-LEVEL */
-				selector_t ss_sel;
-				WORD new_sp, new_ss;
-
-				if (CPU_INST_OP32) {
-					CHECK_STACK_POP(&CPU_STAT_SREG(CPU_SS_INDEX), CPU_ESP, 8);
-					if (CPU_STAT_SS32) {
-						new_sp = cpu_vmemoryread_d(CPU_SS_INDEX, CPU_ESP);
-						new_ss = cpu_vmemoryread_d(CPU_SS_INDEX, CPU_ESP + 4);
-					} else {
-						new_sp = cpu_vmemoryread_d(CPU_SS_INDEX, CPU_SP);
-						new_ss = cpu_vmemoryread_d(CPU_SS_INDEX, CPU_SP + 4);
-					}
-				} else {
-					CHECK_STACK_POP(&CPU_STAT_SREG(CPU_SS_INDEX), CPU_ESP, 4);
-					if (CPU_STAT_SS32) {
-						new_sp = cpu_vmemoryread_w(CPU_SS_INDEX, CPU_ESP);
-						new_ss = cpu_vmemoryread_w(CPU_SS_INDEX, CPU_ESP + 2);
-					} else {
-						new_sp = cpu_vmemoryread_w(CPU_SS_INDEX, CPU_SP);
-						new_ss = cpu_vmemoryread_w(CPU_SS_INDEX, CPU_SP + 2);
-					}
-				}
-
-				rv = parse_selector(&ss_sel, new_ss);
-				if (rv < 0) {
-					EXCEPTION(GP_EXCEPTION, ss_sel.idx);
-				}
-
-				/* check stack segment descriptor */
-				/* check privilege level */
-				if ((ss_sel.rpl != iret_sel.rpl)
-				 || (ss_sel.desc.dpl != iret_sel.rpl)
-				 || !ss_sel.desc.s
-				 || !ss_sel.desc.u.seg.wr) {
-					EXCEPTION(GP_EXCEPTION, ss_sel.idx);
-				}
-
-				/* not present */
-				if (selector_is_not_present(&ss_sel)) {
-					EXCEPTION(SS_EXCEPTION, ss_sel.idx);
-				}
-			} else {
-				VERBOSE(("RETURN-TO-SAME-PRIVILEGE-LEVEL"));
-			}
+	if (CPU_STAT_SS32) {
+		sp = CPU_ESP;
+	} else {
+		sp = CPU_SP;
+	}
+	SS_POP_CHECK(sp, 36);
 
-			/* check code segment limit */
-			if (new_ip > iret_sel.desc.u.seg.limit) {
-				EXCEPTION(GP_EXCEPTION, 0);
-			}
+	if (new_ip > 0xffff) {
+		EXCEPTION(GP_EXCEPTION, 0);
+	}
 
-			/* set new register */
-			load_cs(iret_sel.selector, &iret_sel.desc, iret_sel.rpl);
-			SET_EIP(new_ip);
-
-			mask = 0;
-			if (CPU_INST_OP32)
-				mask |= RF_FLAG;
-			if (CPU_STAT_CPL <= CPU_STAT_IOPL)
-				mask |= I_FLAG;
-			if (CPU_STAT_CPL == 0) {
-				mask |= IOPL_FLAG;
-				if (CPU_INST_OP32)
-					mask |= VM_FLAG|VIF_FLAG|VIP_FLAG;
-			}
-			set_eflags(new_flags, mask);
+	new_sp = cpu_vmemoryread_d(CPU_SS_INDEX, sp + 12);
+	segsel[CPU_SS_INDEX] = cpu_vmemoryread_w(CPU_SS_INDEX, sp + 16);
+	segsel[CPU_ES_INDEX] = cpu_vmemoryread_w(CPU_SS_INDEX, sp + 20);
+	segsel[CPU_DS_INDEX] = cpu_vmemoryread_w(CPU_SS_INDEX, sp + 24);
+	segsel[CPU_FS_INDEX] = cpu_vmemoryread_w(CPU_SS_INDEX, sp + 28);
+	segsel[CPU_GS_INDEX] = cpu_vmemoryread_w(CPU_SS_INDEX, sp + 32);
+	segsel[CPU_CS_INDEX] = new_cs;
 
-			if (iret_sel.rpl > CPU_STAT_CPL) {
-				selector_t temp_sel;
-				int i;
-
-				/* RETURN-OUTER-PRIVILEGE-LEVEL */
-				/* check segment register */
-				for (i = 0; i < CPU_SEGREG_NUM; i++) {
-					if ((i == CPU_CS_INDEX) || (i == CPU_SS_INDEX))
-						continue;
-
-					rv = parse_selector(&temp_sel, CPU_REGS_SREG(i));
-					if (rv < 0) {
-						CPU_REGS_SREG(i) = 0;
-						CPU_STAT_SREG(i).valid = 0;
-						continue;
-					}
-
-					if ((!temp_sel.desc.u.seg.c || !temp_sel.desc.u.seg.ec)
-					 && (CPU_STAT_CPL > temp_sel.desc.dpl)) {
-						CPU_REGS_SREG(i) = 0;
-						CPU_STAT_SREG(i).valid = 0;
-						continue;
-					}
-				}
-			}
+	for (i = 0; i < CPU_SEGREG_NUM; i++) {
+		segdesc_init(i, segsel[i], &CPU_STAT_SREG(i));
+	}
+
+	CPU_ESP = new_sp;
+	CPU_EIP = new_ip;
+
+	/* to VM86 mode */
+	set_eflags(new_flags, IOPL_FLAG|I_FLAG|VM_FLAG|RF_FLAG);
+}
+
+/*---
+ * IRET_pm: VM_FLAG
+ */
+static void
+IRET_pm_return_from_vm86(UINT16 new_cs, UINT32 new_ip, UINT32 new_flags)
+{
+	UINT stacksize;
+
+	VERBOSE(("IRET_pm: virtual-8086 mode: VM=1"));
+
+	if (CPU_STAT_IOPL == CPU_IOPL3) {
+		VERBOSE(("IRET_pm: virtual-8086 mode: IOPL=3"));
+		if (CPU_INST_OP32) {
+			stacksize = 12;
+		} else {
+			stacksize = 6;
+		}
+		if (CPU_STAT_SS32) {
+			CPU_ESP += stacksize;
+		} else {
+			CPU_SP += stacksize;
 		}
+
+		LOAD_SEGREG(CPU_CS_INDEX, new_cs);
+		if (new_ip > CPU_STAT_CS_LIMIT) {
+			EXCEPTION(GP_EXCEPTION, 0);
+		}
+		CPU_EIP = new_ip;
+
+		set_eflags(new_flags, I_FLAG|RF_FLAG);
+		return;
 	}
+	VERBOSE(("IRET_pm: trap to virtual-8086 monitor: VM=1, IOPL<3"));
+	EXCEPTION(GP_EXCEPTION, 0);
 }