Bochs/bochs/cpu/call_far.cc

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////////////////////////////////////////////////////////////////////////
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// $Id: call_far.cc,v 1.6 2005-08-04 19:38:49 sshwarts Exp $
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/////////////////////////////////////////////////////////////////////////
//
// Copyright (C) 2001 MandrakeSoft S.A.
//
// MandrakeSoft S.A.
// 43, rue d'Aboukir
// 75002 Paris - France
// http://www.linux-mandrake.com/
// http://www.mandrakesoft.com/
//
// This library is free software; you can redistribute it and/or
// modify it under the terms of the GNU Lesser General Public
// License as published by the Free Software Foundation; either
// version 2 of the License, or (at your option) any later version.
//
// This library is distributed in the hope that it will be useful,
// but WITHOUT ANY WARRANTY; without even the implied warranty of
// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
// Lesser General Public License for more details.
//
// You should have received a copy of the GNU Lesser General Public
// License along with this library; if not, write to the Free Software
// Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA
//
#define NEED_CPU_REG_SHORTCUTS 1
#include "bochs.h"
#define LOG_THIS BX_CPU_THIS_PTR
#if BX_SUPPORT_X86_64==0
// Make life easier merging cpu64 & cpu code.
#define RIP EIP
#endif
void BX_CPP_AttrRegparmN(3)
BX_CPU_C::call_protected(bxInstruction_c *i, Bit16u cs_raw, bx_address disp)
{
bx_selector_t cs_selector;
Bit32u dword1, dword2;
bx_descriptor_t cs_descriptor;
/* new cs selector must not be null, else #GP(0) */
if ((cs_raw & 0xfffc) == 0) {
BX_ERROR(("call_protected: CS selector null"));
exception(BX_GP_EXCEPTION, 0, 0);
}
parse_selector(cs_raw, &cs_selector);
// check new CS selector index within its descriptor limits,
// else #GP(new CS selector)
fetch_raw_descriptor(&cs_selector, &dword1, &dword2, BX_GP_EXCEPTION);
parse_descriptor(dword1, dword2, &cs_descriptor);
// examine AR byte of selected descriptor for various legal values
if (cs_descriptor.valid==0) {
BX_ERROR(("call_protected: invalid CS descriptor"));
exception(BX_GP_EXCEPTION, cs_raw & 0xfffc, 0);
}
if (cs_descriptor.segment) // normal segment
{
check_cs(&cs_descriptor, cs_raw, BX_SELECTOR_RPL(cs_raw), CPL);
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#if BX_SUPPORT_X86_64
if (i->os64L()) {
// push return address onto stack (CS padded to 64bits)
push_64((Bit64u) BX_CPU_THIS_PTR sregs[BX_SEG_REG_CS].selector.value);
push_64(RIP);
}
else
#endif
if (i->os32L()) {
// push return address onto stack (CS padded to 32bits)
push_32((Bit32u) BX_CPU_THIS_PTR sregs[BX_SEG_REG_CS].selector.value);
push_32(EIP);
}
else {
// push return address onto stack
push_16(BX_CPU_THIS_PTR sregs[BX_SEG_REG_CS].selector.value);
push_16(IP);
}
// load code segment descriptor into CS cache
// load CS with new code segment selector
// set RPL of CS to CPL
branch_far64(&cs_selector, &cs_descriptor, disp, CPL);
return;
}
else { // gate & special segment
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bx_descriptor_t gate_descriptor = cs_descriptor;
bx_selector_t gate_selector = cs_selector;
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Bit32u new_EIP;
Bit16u dest_selector;
Bit16u raw_tss_selector;
bx_selector_t tss_selector;
bx_descriptor_t tss_descriptor;
Bit32u temp_eIP;
// descriptor DPL must be >= CPL else #GP(gate selector)
if (gate_descriptor.dpl < CPL) {
BX_ERROR(("call_protected: descriptor.dpl < CPL"));
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exception(BX_GP_EXCEPTION, cs_raw & 0xfffc, 0);
}
// descriptor DPL must be >= gate selector RPL else #GP(gate selector)
if (gate_descriptor.dpl < gate_selector.rpl) {
BX_ERROR(("call_protected: descriptor.dpl < selector.rpl"));
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exception(BX_GP_EXCEPTION, cs_raw & 0xfffc, 0);
}
// gate descriptor must be present else #NP(gate selector)
if (! IS_PRESENT(gate_descriptor)) {
BX_ERROR(("call_protected: gate.p == 0"));
exception(BX_NP_EXCEPTION, cs_raw & 0xfffc, 0);
}
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#if BX_SUPPORT_X86_64
if (IsLongMode()) {
if (gate_descriptor.type != BX_386_CALL_GATE) {
BX_ERROR(("call_protected: gate type %u unsupported in long mode", (unsigned) gate_descriptor.type));
exception(BX_GP_EXCEPTION, cs_raw & 0xfffc, 0);
}
else {
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call_gate64(&gate_descriptor);
return;
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}
}
#endif
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switch (gate_descriptor.type) {
case BX_SYS_SEGMENT_AVAIL_286_TSS:
case BX_SYS_SEGMENT_AVAIL_386_TSS:
if (gate_descriptor.type==BX_SYS_SEGMENT_AVAIL_286_TSS)
BX_DEBUG(("call_protected: 16bit available TSS"));
else
BX_DEBUG(("call_protected: 32bit available TSS"));
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// SWITCH_TASKS _without_ nesting to TSS
task_switch(&gate_selector, &gate_descriptor,
BX_TASK_FROM_CALL_OR_INT, dword1, dword2);
// EIP must be in code seg limit, else #GP(0)
if (EIP > BX_CPU_THIS_PTR sregs[BX_SEG_REG_CS].cache.u.segment.limit_scaled) {
BX_ERROR(("call_protected: EIP not within CS limits"));
exception(BX_GP_EXCEPTION, 0, 0);
}
return;
case BX_TASK_GATE:
// examine selector to TSS, given in Task Gate descriptor
// must specify global in the local/global bit else #TS(TSS selector)
raw_tss_selector = gate_descriptor.u.taskgate.tss_selector;
parse_selector(raw_tss_selector, &tss_selector);
if (tss_selector.ti) {
BX_ERROR(("call_protected: tss_selector.ti=1"));
exception(BX_TS_EXCEPTION, raw_tss_selector & 0xfffc, 0);
}
// index must be within GDT limits else #TS(TSS selector)
fetch_raw_descriptor(&tss_selector, &dword1, &dword2, BX_TS_EXCEPTION);
// descriptor AR byte must specify available TSS
// else #TS(TSS selector)
parse_descriptor(dword1, dword2, &tss_descriptor);
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if (tss_descriptor.valid==0 || tss_descriptor.segment) {
BX_ERROR(("call_protected: TSS selector points to bad TSS"));
exception(BX_TS_EXCEPTION, raw_tss_selector & 0xfffc, 0);
}
if (tss_descriptor.type!=9 && tss_descriptor.type!=1) {
BX_ERROR(("call_protected: TSS selector points to bad TSS"));
exception(BX_TS_EXCEPTION, raw_tss_selector & 0xfffc, 0);
}
// task state segment must be present, else #NP(tss selector)
if (! IS_PRESENT(tss_descriptor)) {
BX_ERROR(("call_protected: task descriptor.p == 0"));
exception(BX_NP_EXCEPTION, raw_tss_selector & 0xfffc, 0);
}
// SWITCH_TASKS without nesting to TSS
task_switch(&tss_selector, &tss_descriptor,
BX_TASK_FROM_CALL_OR_INT, dword1, dword2);
// EIP must be within code segment limit, else #TS(0)
if (BX_CPU_THIS_PTR sregs[BX_SEG_REG_CS].cache.u.segment.d_b)
temp_eIP = EIP;
else
temp_eIP = IP;
if (temp_eIP > BX_CPU_THIS_PTR sregs[BX_SEG_REG_CS].cache.u.segment.limit_scaled)
{
BX_ERROR(("call_protected: EIP > CS.limit"));
exception(BX_GP_EXCEPTION, 0, 0);
}
return;
case BX_286_CALL_GATE:
case BX_386_CALL_GATE:
// examine code segment selector in call gate descriptor
if (gate_descriptor.type == BX_286_CALL_GATE) {
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BX_DEBUG(("call_protected: CALL 16bit call gate"));
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dest_selector = gate_descriptor.u.gate286.dest_selector;
new_EIP = gate_descriptor.u.gate286.dest_offset;
}
else {
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BX_DEBUG(("call_protected: CALL 32bit call gate"));
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dest_selector = gate_descriptor.u.gate386.dest_selector;
new_EIP = gate_descriptor.u.gate386.dest_offset;
}
// selector must not be null else #GP(0)
if ( (dest_selector & 0xfffc) == 0 ) {
BX_ERROR(("call_protected: selector in gate null"));
exception(BX_GP_EXCEPTION, 0, 0);
}
parse_selector(dest_selector, &cs_selector);
// selector must be within its descriptor table limits,
// else #GP(code segment selector)
fetch_raw_descriptor(&cs_selector, &dword1, &dword2, BX_GP_EXCEPTION);
parse_descriptor(dword1, dword2, &cs_descriptor);
// AR byte of selected descriptor must indicate code segment,
// else #GP(code segment selector)
// DPL of selected descriptor must be <= CPL,
// else #GP(code segment selector)
if (cs_descriptor.valid==0 || cs_descriptor.segment==0 ||
cs_descriptor.u.segment.executable==0 ||
cs_descriptor.dpl > CPL)
{
BX_ERROR(("call_protected: selected descriptor is not code"));
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exception(BX_GP_EXCEPTION, dest_selector & 0xfffc, 0);
}
// code segment must be present else #NP(selector)
if (! IS_PRESENT(cs_descriptor)) {
BX_ERROR(("call_protected: code segment not present !"));
exception(BX_NP_EXCEPTION, dest_selector & 0xfffc, 0);
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}
// CALL GATE TO MORE PRIVILEGE
// if non-conforming code segment and DPL < CPL then
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if ( (cs_descriptor.u.segment.c_ed==0) &&
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(cs_descriptor.dpl < CPL) )
{
Bit16u SS_for_cpl_x;
Bit32u ESP_for_cpl_x;
bx_selector_t ss_selector;
bx_descriptor_t ss_descriptor;
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unsigned room_needed, param_count;
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Bit16u return_SS, return_CS;
Bit32u return_ESP, return_EIP;
Bit32u return_ss_base;
Bit16u parameter_word[32];
Bit32u parameter_dword[32];
Bit32u temp_ESP;
BX_DEBUG(("CALL GATE TO MORE PRIVILEGE LEVEL"));
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// Help for OS/2
BX_CPU_THIS_PTR except_chk = 1;
BX_CPU_THIS_PTR except_cs = BX_CPU_THIS_PTR sregs[BX_SEG_REG_CS].selector.value;
BX_CPU_THIS_PTR except_ss = BX_CPU_THIS_PTR sregs[BX_SEG_REG_SS].selector.value;
// get new SS selector for new privilege level from TSS
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get_SS_ESP_from_TSS(cs_descriptor.dpl, &SS_for_cpl_x, &ESP_for_cpl_x);
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// check selector & descriptor for new SS:
// selector must not be null, else #TS(0)
if ( (SS_for_cpl_x & 0xfffc) == 0 ) {
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BX_ERROR(("call_protected: new SS null"));
exception(BX_TS_EXCEPTION, 0, 0);
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}
// selector index must be within its descriptor table limits,
// else #TS(SS selector)
parse_selector(SS_for_cpl_x, &ss_selector);
fetch_raw_descriptor(&ss_selector, &dword1, &dword2, BX_TS_EXCEPTION);
parse_descriptor(dword1, dword2, &ss_descriptor);
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// selector's RPL must equal DPL of code segment,
// else #TS(SS selector)
if (ss_selector.rpl != cs_descriptor.dpl) {
BX_DEBUG(("call_protected: SS selector.rpl != CS descr.dpl"));
exception(BX_TS_EXCEPTION, SS_for_cpl_x & 0xfffc, 0);
}
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// stack segment DPL must equal DPL of code segment,
// else #TS(SS selector)
if (ss_descriptor.dpl != cs_descriptor.dpl) {
BX_ERROR(("call_protected: SS descr.rpl != CS descr.dpl"));
exception(BX_TS_EXCEPTION, SS_for_cpl_x & 0xfffc, 0);
}
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// descriptor must indicate writable data segment,
// else #TS(SS selector)
if (ss_descriptor.valid==0 || ss_descriptor.segment==0 ||
ss_descriptor.u.segment.executable ||
ss_descriptor.u.segment.r_w==0)
{
BX_ERROR(("call_protected: ss descriptor not writable data seg"));
exception(BX_TS_EXCEPTION, SS_for_cpl_x & 0xfffc, 0);
}
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// segment must be present, else #SS(SS selector)
if (! IS_PRESENT(ss_descriptor)) {
BX_ERROR(("call_protected: ss descriptor not present"));
exception(BX_SS_EXCEPTION, SS_for_cpl_x & 0xfffc, 0);
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}
if ( cs_descriptor.u.segment.d_b )
// new stack must have room for parameters plus 16 bytes
room_needed = 16;
else
// new stack must have room for parameters plus 8 bytes
room_needed = 8;
if (gate_descriptor.type==BX_286_CALL_GATE) {
// get word count from call gate, mask to 5 bits
param_count = gate_descriptor.u.gate286.word_count & 0x1f;
room_needed += param_count*2;
}
else {
// get word count from call gate, mask to 5 bits
param_count = gate_descriptor.u.gate386.dword_count & 0x1f;
room_needed += param_count*4;
}
// new stack must have room for parameters plus return info
// else #SS(SS selector)
if ( !can_push(&ss_descriptor, ESP_for_cpl_x, room_needed) ) {
BX_INFO(("call_protected: stack doesn't have room"));
exception(BX_SS_EXCEPTION, SS_for_cpl_x & 0xfffc, 0);
}
// new eIP must be in code segment limit else #GP(0)
if ( new_EIP > cs_descriptor.u.segment.limit_scaled ) {
BX_ERROR(("call_protected: EIP not within CS limits"));
exception(BX_GP_EXCEPTION, 0, 0);
}
// save return SS:eSP to be pushed on new stack
return_SS = BX_CPU_THIS_PTR sregs[BX_SEG_REG_SS].selector.value;
if (BX_CPU_THIS_PTR sregs[BX_SEG_REG_SS].cache.u.segment.d_b)
return_ESP = ESP;
else
return_ESP = SP;
return_ss_base = BX_CPU_THIS_PTR get_segment_base(BX_SEG_REG_SS);
// save return CS:eIP to be pushed on new stack
return_CS = BX_CPU_THIS_PTR sregs[BX_SEG_REG_CS].selector.value;
if ( cs_descriptor.u.segment.d_b )
return_EIP = EIP;
else
return_EIP = IP;
if (gate_descriptor.type==BX_286_CALL_GATE) {
for (unsigned i=0; i<param_count; i++) {
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access_linear(return_ss_base + return_ESP + i*2,
2, 0, BX_READ, &parameter_word[i]);
}
}
else {
for (unsigned i=0; i<param_count; i++) {
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access_linear(return_ss_base + return_ESP + i*4,
4, 0, BX_READ, &parameter_dword[i]);
}
}
/* load new SS:SP value from TSS */
/* load SS descriptor */
load_ss(&ss_selector, &ss_descriptor, ss_descriptor.dpl);
if (ss_descriptor.u.segment.d_b)
ESP = ESP_for_cpl_x;
else
SP = (Bit16u) ESP_for_cpl_x;
/* load new CS:IP value from gate */
/* load CS descriptor */
/* set CPL to stack segment DPL */
/* set RPL of CS to CPL */
load_cs(&cs_selector, &cs_descriptor, cs_descriptor.dpl);
EIP = new_EIP;
// push pointer of old stack onto new stack
if (gate_descriptor.type==BX_386_CALL_GATE) {
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push_32(return_SS);
push_32(return_ESP);
}
else {
push_16(return_SS);
push_16((Bit16u) return_ESP);
}
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/* get word count from call gate, mask to 5 bits */
/* copy parameters from old stack onto new stack */
if (BX_CPU_THIS_PTR sregs[BX_SEG_REG_SS].cache.u.segment.d_b)
temp_ESP = ESP;
else
temp_ESP = SP;
if (gate_descriptor.type==BX_286_CALL_GATE) {
for (unsigned i=param_count; i>0; i--) {
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push_16(parameter_word[i-1]);
}
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// push return address onto new stack
push_16(return_CS);
push_16((Bit16u) return_EIP);
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}
else {
for (unsigned i=param_count; i>0; i--) {
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push_32(parameter_dword[i-1]);
}
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// push return address onto new stack
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push_32(return_CS);
push_32(return_EIP);
}
// Help for OS/2
BX_CPU_THIS_PTR except_chk = 0;
}
else // CALL GATE TO SAME PRIVILEGE
{
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BX_DEBUG(("CALL GATE TO SAME PRIVILEGE"));
if (gate_descriptor.type == BX_386_CALL_GATE) {
// call gate 32bit, push return address onto stack
push_32(BX_CPU_THIS_PTR sregs[BX_SEG_REG_CS].selector.value);
push_32(EIP);
}
else {
// call gate 16bit, push return address onto stack
push_16(BX_CPU_THIS_PTR sregs[BX_SEG_REG_CS].selector.value);
push_16(IP);
}
// load CS:EIP from gate
// load code segment descriptor into CS register
// set RPL of CS to CPL
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branch_far32(&cs_selector, &cs_descriptor, new_EIP, CPL);
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}
return;
default:
BX_ERROR(("call_protected: gate type %u unsupported", (unsigned) cs_descriptor.type));
exception(BX_GP_EXCEPTION, cs_raw & 0xfffc, 0);
}
}
}
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#if BX_SUPPORT_X86_64
void BX_CPP_AttrRegparmN(1)
BX_CPU_C::call_gate64(bx_descriptor_t *gate_descriptor)
{
bx_selector_t cs_selector;
Bit32u dword1, dword2, dword3;
bx_descriptor_t cs_descriptor;
// examine code segment selector in call gate descriptor
BX_DEBUG(("call_gate64: CALL 64bit call gate"));
Bit16u dest_selector = gate_descriptor->u.gate386.dest_selector;
// selector must not be null else #GP(0)
if ( (dest_selector & 0xfffc) == 0 ) {
BX_ERROR(("call_gate64: selector in gate null"));
exception(BX_GP_EXCEPTION, 0, 0);
}
parse_selector(dest_selector, &cs_selector);
// selector must be within its descriptor table limits,
// else #GP(code segment selector)
fetch_raw_descriptor64(&cs_selector, &dword1, &dword2, &dword3, BX_GP_EXCEPTION);
parse_descriptor(dword1, dword2, &cs_descriptor);
Bit64u new_RIP = gate_descriptor->u.gate386.dest_offset;
new_RIP |= ((Bit64u)dword3 << 32);
// AR byte of selected descriptor must indicate code segment,
// else #GP(code segment selector)
// DPL of selected descriptor must be <= CPL,
// else #GP(code segment selector)
if (cs_descriptor.valid==0 || cs_descriptor.segment==0 ||
cs_descriptor.u.segment.executable==0 ||
cs_descriptor.dpl > CPL)
{
BX_ERROR(("call_gate64: selected descriptor is not code"));
exception(BX_GP_EXCEPTION, dest_selector & 0xfffc, 0);
}
// In long mode, only 64-bit call gates are allowed, and they must point
// to 64-bit code segments, else #GP(selector)
if (! IS_LONG64_SEGMENT(cs_descriptor) || cs_descriptor.u.segment.d_b)
{
BX_ERROR(("call_gate64: not 64-bit code segment in call gate 64"));
exception(BX_GP_EXCEPTION, dest_selector & 0xfffc, 0);
}
// code segment must be present else #NP(selector)
if (! IS_PRESENT(cs_descriptor)) {
BX_ERROR(("call_gate64: code segment not present !"));
exception(BX_NP_EXCEPTION, dest_selector & 0xfffc, 0);
}
Bit16u old_CS = BX_CPU_THIS_PTR sregs[BX_SEG_REG_CS].selector.value;
Bit64u old_RIP = RIP;
// CALL GATE TO MORE PRIVILEGE
// if non-conforming code segment and DPL < CPL then
if ( (cs_descriptor.u.segment.c_ed==0) &&
(cs_descriptor.dpl < CPL) )
{
Bit64u RSP_for_cpl_x;
BX_DEBUG(("CALL GATE TO MORE PRIVILEGE LEVEL"));
// get new RSP for new privilege level from TSS
get_RSP_from_TSS(cs_descriptor.dpl, &RSP_for_cpl_x);
if (! IsCanonical(RSP_for_cpl_x)) {
BX_ERROR(("call_gate64: canonical address failure %08x%08x",
(Bit32u)(RSP_for_cpl_x >> 32), (Bit32u)(RSP_for_cpl_x & 0xffffffff)));
exception(BX_GP_EXCEPTION, 0, 0);
}
Bit16u old_SS = BX_CPU_THIS_PTR sregs[BX_SEG_REG_SS].selector.value;
Bit64u old_RSP = RSP;
bx_selector_t ss_selector;
bx_descriptor_t ss_descriptor;
// set up a null descriptor
parse_selector(0, &ss_selector);
parse_descriptor(0, 0, &ss_descriptor);
// load CS:RIP (guaranteed to be in 64 bit mode)
branch_far64(&cs_selector, &cs_descriptor, new_RIP, cs_descriptor.dpl);
// set up null SS descriptor
load_ss(&ss_selector, &ss_descriptor, cs_descriptor.dpl);
RSP = RSP_for_cpl_x;
// push old stack long pointer onto new stack
push_64(old_SS);
push_64(old_RSP);
// push long pointer to return address onto new stack
push_64(old_CS);
push_64(old_RIP);
}
else
{
BX_DEBUG(("CALL GATE TO SAME PRIVILEGE"));
// make sure that push CS:RIP will not fail
if (! IsCanonical(RSP)) {
BX_ERROR(("call_gate64: canonical address failure %08x%08x",
(Bit32u)(RSP >> 32), (Bit32u)(RSP & 0xffffffff)));
exception(BX_GP_EXCEPTION, 0, 0);
}
// load CS:RIP (guaranteed to be in 64 bit mode)
branch_far64(&cs_selector, &cs_descriptor, new_RIP, CPL);
// push return address onto stack
push_64(old_CS);
push_64(old_RIP);
}
}
#endif