void BX_CPU_C::real_mode_int(Bit8u vector, bx_bool push_error, Bit16u error_code)
{
if ((vector*4+3) > BX_CPU_THIS_PTR idtr.limit) {
BX_ERROR(("interrupt(real mode) vector > idtr.limit"));
exception(BX_GP_EXCEPTION, 0);
}
push_16((Bit16u) read_eflags());
push_16(BX_CPU_THIS_PTR sregs[BX_SEG_REG_CS].selector.value);
push_16(IP);
Bit16u new_ip = system_read_word(BX_CPU_THIS_PTR idtr.base + 4 * vector);
// CS.LIMIT can't change when in real/v8086 mode
if (new_ip > BX_CPU_THIS_PTR sregs[BX_SEG_REG_CS].cache.u.segment.limit_scaled) {
BX_ERROR(("interrupt(real mode): instruction pointer not within code segment limits"));
exception(BX_GP_EXCEPTION, 0);
}
Bit16u cs_selector = system_read_word(BX_CPU_THIS_PTR idtr.base + 4 * vector + 2);
load_seg_reg(&BX_CPU_THIS_PTR sregs[BX_SEG_REG_CS], cs_selector);
EIP = new_ip;
/* INT affects the following flags: I,T */
BX_CPU_THIS_PTR clear_IF();
BX_CPU_THIS_PTR clear_TF();
#if BX_CPU_LEVEL >= 4
BX_CPU_THIS_PTR clear_AC();
#endif
BX_CPU_THIS_PTR clear_RF();
}
void BX_CPU_C::real_mode_int(Bit8u vector, bx_bool is_INT, bx_bool is_error_code, Bit16u error_code)
{
// real mode interrupt
Bit16u cs_selector, ip;
if ((vector*4+3) > BX_CPU_THIS_PTR idtr.limit) {
BX_ERROR(("interrupt(real mode) vector > idtr.limit"));
exception(BX_GP_EXCEPTION, 0, 0);
}
push_16((Bit16u) read_eflags());
cs_selector = BX_CPU_THIS_PTR sregs[BX_SEG_REG_CS].selector.value;
push_16(cs_selector);
ip = EIP;
push_16(ip);
access_read_linear(BX_CPU_THIS_PTR idtr.base + 4 * vector, 2, 0, BX_READ, &ip);
EIP = (Bit32u) ip;
access_read_linear(BX_CPU_THIS_PTR idtr.base + 4 * vector + 2, 2, 0, BX_READ, &cs_selector);
load_seg_reg(&BX_CPU_THIS_PTR sregs[BX_SEG_REG_CS], cs_selector);
/* INT affects the following flags: I,T */
BX_CPU_THIS_PTR clear_IF();
BX_CPU_THIS_PTR clear_TF();
#if BX_CPU_LEVEL >= 4
BX_CPU_THIS_PTR clear_AC();
#endif
BX_CPU_THIS_PTR clear_RF();
}
int BX_CPU_C::v86_redirect_interrupt(Bit8u vector)
{
#if BX_CPU_LEVEL >= 5
if (BX_CPU_THIS_PTR cr4.get_VME())
{
bx_address tr_base = BX_CPU_THIS_PTR tr.cache.u.segment.base;
if (BX_CPU_THIS_PTR tr.cache.u.segment.limit_scaled < 103) {
BX_ERROR(("INT_Ib(): TR.limit < 103 in VME"));
exception(BX_GP_EXCEPTION, 0);
}
Bit32u io_base = system_read_word(tr_base + 102), offset = io_base - 32 + (vector >> 3);
if (offset > BX_CPU_THIS_PTR tr.cache.u.segment.limit_scaled) {
BX_ERROR(("INT_Ib(): failed to fetch VME redirection bitmap"));
exception(BX_GP_EXCEPTION, 0);
}
Bit8u vme_redirection_bitmap = system_read_byte(tr_base + offset);
if (!(vme_redirection_bitmap & (1 << (vector & 7))))
{
// redirect interrupt through virtual-mode idt
Bit16u temp_flags = (Bit16u) read_eflags();
Bit16u temp_CS = system_read_word(vector*4 + 2);
Bit16u temp_IP = system_read_word(vector*4);
if (BX_CPU_THIS_PTR get_IOPL() < 3) {
temp_flags |= EFlagsIOPLMask;
if (BX_CPU_THIS_PTR get_VIF())
temp_flags |= EFlagsIFMask;
else
temp_flags &= ~EFlagsIFMask;
}
Bit16u old_IP = IP;
Bit16u old_CS = BX_CPU_THIS_PTR sregs[BX_SEG_REG_CS].selector.value;
push_16(temp_flags);
// push return address onto new stack
push_16(old_CS);
push_16(old_IP);
load_seg_reg(&BX_CPU_THIS_PTR sregs[BX_SEG_REG_CS], (Bit16u) temp_CS);
EIP = temp_IP;
BX_CPU_THIS_PTR clear_TF();
BX_CPU_THIS_PTR clear_RF();
if (BX_CPU_THIS_PTR get_IOPL() == 3)
BX_CPU_THIS_PTR clear_IF();
else
BX_CPU_THIS_PTR clear_VIF();
return 1;
}
}
void
bx_cpu_c::PUSH_Iw(BxInstruction_t *i)
{
#if BX_CPU_LEVEL < 2
BX_PANIC(("PUSH_Iv: not supported on 8086!"));
#else
Bit16u imm16;
imm16 = i->Iw;
push_16(imm16);
#endif
}
void
bx_cpu_c::PUSH_Ew(BxInstruction_t *i)
{
Bit16u op1_16;
/* op1_16 is a register or memory reference */
if (i->mod == 0xc0) {
op1_16 = BX_READ_16BIT_REG(i->rm);
}
else {
/* pointer, segment address pair */
read_virtual_word(i->seg, i->rm_addr, &op1_16);
}
push_16(op1_16);
}
void
bx_cpu_c::PUSHAD16(BxInstruction_t *i)
{
#if BX_CPU_LEVEL < 2
BX_PANIC(("PUSHAD: not supported on an 8086"));
#else
Bit32u temp_ESP;
Bit16u sp;
if (bx_cpu. sregs[BX_SEG_REG_SS].cache.u.segment.d_b)
temp_ESP = ESP;
else
temp_ESP = SP;
#if BX_CPU_LEVEL >= 2
if (protected_mode()) {
if ( !can_push(&bx_cpu. sregs[BX_SEG_REG_SS].cache, temp_ESP, 16) ) {
BX_PANIC(("PUSHA(): stack doesn't have enough room!"));
exception(BX_SS_EXCEPTION, 0, 0);
return;
}
}
else
#endif
{
if (temp_ESP < 16)
BX_PANIC(("pushad: eSP < 16"));
}
sp = SP;
/* ??? optimize this by using virtual write, all checks passed */
push_16(AX);
push_16(CX);
push_16(DX);
push_16(BX);
push_16(sp);
push_16(BP);
push_16(SI);
push_16(DI);
#endif
}
void BX_CPU_C::protected_mode_int(Bit8u vector, unsigned soft_int, bx_bool push_error, Bit16u error_code)
{
bx_descriptor_t gate_descriptor, cs_descriptor;
bx_selector_t cs_selector;
Bit16u raw_tss_selector;
bx_selector_t tss_selector;
bx_descriptor_t tss_descriptor;
Bit16u gate_dest_selector;
Bit32u gate_dest_offset;
// interrupt vector must be within IDT table limits,
// else #GP(vector*8 + 2 + EXT)
if ((vector*8 + 7) > BX_CPU_THIS_PTR idtr.limit) {
BX_ERROR(("interrupt(): vector must be within IDT table limits, IDT.limit = 0x%x", BX_CPU_THIS_PTR idtr.limit));
exception(BX_GP_EXCEPTION, vector*8 + 2);
}
Bit64u desctmp = system_read_qword(BX_CPU_THIS_PTR idtr.base + vector*8);
Bit32u dword1 = GET32L(desctmp);
Bit32u dword2 = GET32H(desctmp);
parse_descriptor(dword1, dword2, &gate_descriptor);
if ((gate_descriptor.valid==0) || gate_descriptor.segment) {
BX_ERROR(("interrupt(): gate descriptor is not valid sys seg (vector=0x%02x)", vector));
exception(BX_GP_EXCEPTION, vector*8 + 2);
}
// descriptor AR byte must indicate interrupt gate, trap gate,
// or task gate, else #GP(vector*8 + 2 + EXT)
switch (gate_descriptor.type) {
case BX_TASK_GATE:
case BX_286_INTERRUPT_GATE:
case BX_286_TRAP_GATE:
case BX_386_INTERRUPT_GATE:
case BX_386_TRAP_GATE:
break;
default:
BX_ERROR(("interrupt(): gate.type(%u) != {5,6,7,14,15}",
(unsigned) gate_descriptor.type));
exception(BX_GP_EXCEPTION, vector*8 + 2);
}
// if software interrupt, then gate descripor DPL must be >= CPL,
// else #GP(vector * 8 + 2 + EXT)
if (soft_int && gate_descriptor.dpl < CPL) {
BX_ERROR(("interrupt(): soft_int && (gate.dpl < CPL)"));
exception(BX_GP_EXCEPTION, vector*8 + 2);
}
// Gate must be present, else #NP(vector * 8 + 2 + EXT)
if (! IS_PRESENT(gate_descriptor)) {
BX_ERROR(("interrupt(): gate not present"));
exception(BX_NP_EXCEPTION, vector*8 + 2);
}
switch (gate_descriptor.type) {
case BX_TASK_GATE:
// examine selector to TSS, given in task gate descriptor
raw_tss_selector = gate_descriptor.u.taskgate.tss_selector;
parse_selector(raw_tss_selector, &tss_selector);
// must specify global in the local/global bit,
// else #GP(TSS selector)
if (tss_selector.ti) {
BX_ERROR(("interrupt(): tss_selector.ti=1 from gate descriptor - #GP(tss_selector)"));
exception(BX_GP_EXCEPTION, raw_tss_selector & 0xfffc);
}
// index must be within GDT limits, else #TS(TSS selector)
fetch_raw_descriptor(&tss_selector, &dword1, &dword2, BX_GP_EXCEPTION);
parse_descriptor(dword1, dword2, &tss_descriptor);
// AR byte must specify available TSS,
// else #GP(TSS selector)
if (tss_descriptor.valid==0 || tss_descriptor.segment) {
BX_ERROR(("interrupt(): TSS selector points to invalid or bad TSS - #GP(tss_selector)"));
exception(BX_GP_EXCEPTION, raw_tss_selector & 0xfffc);
}
if (tss_descriptor.type!=BX_SYS_SEGMENT_AVAIL_286_TSS &&
tss_descriptor.type!=BX_SYS_SEGMENT_AVAIL_386_TSS)
{
BX_ERROR(("interrupt(): TSS selector points to bad TSS - #GP(tss_selector)"));
exception(BX_GP_EXCEPTION, raw_tss_selector & 0xfffc);
}
// TSS must be present, else #NP(TSS selector)
if (! IS_PRESENT(tss_descriptor)) {
BX_ERROR(("interrupt(): TSS descriptor.p == 0"));
exception(BX_NP_EXCEPTION, raw_tss_selector & 0xfffc);
}
// switch tasks with nesting to TSS
task_switch(0, &tss_selector, &tss_descriptor,
BX_TASK_FROM_INT, dword1, dword2);
RSP_SPECULATIVE;
// if interrupt was caused by fault with error code
// stack limits must allow push of 2 more bytes, else #SS(0)
// push error code onto stack
if (push_error) {
if (tss_descriptor.type >= 9) // TSS386
push_32(error_code);
else
push_16(error_code);
}
// instruction pointer must be in CS limit, else #GP(0)
if (EIP > BX_CPU_THIS_PTR sregs[BX_SEG_REG_CS].cache.u.segment.limit_scaled) {
BX_ERROR(("interrupt(): EIP > CS.limit"));
exception(BX_GP_EXCEPTION, 0);
}
RSP_COMMIT;
return;
case BX_286_INTERRUPT_GATE:
case BX_286_TRAP_GATE:
case BX_386_INTERRUPT_GATE:
case BX_386_TRAP_GATE:
gate_dest_selector = gate_descriptor.u.gate.dest_selector;
gate_dest_offset = gate_descriptor.u.gate.dest_offset;
// examine CS selector and descriptor given in gate descriptor
// selector must be non-null else #GP(EXT)
if ((gate_dest_selector & 0xfffc) == 0) {
BX_ERROR(("int_trap_gate(): selector null"));
exception(BX_GP_EXCEPTION, 0);
}
parse_selector(gate_dest_selector, &cs_selector);
// selector must be within its descriptor table limits
// else #GP(selector+EXT)
fetch_raw_descriptor(&cs_selector, &dword1, &dword2, BX_GP_EXCEPTION);
parse_descriptor(dword1, dword2, &cs_descriptor);
// descriptor AR byte must indicate code seg
// and code segment descriptor DPL<=CPL, else #GP(selector+EXT)
if (cs_descriptor.valid==0 || cs_descriptor.segment==0 ||
IS_DATA_SEGMENT(cs_descriptor.type) ||
cs_descriptor.dpl > CPL)
{
BX_ERROR(("interrupt(): not accessible or not code segment cs=0x%04x", cs_selector.value));
exception(BX_GP_EXCEPTION, cs_selector.value & 0xfffc);
}
// segment must be present, else #NP(selector + EXT)
if (! IS_PRESENT(cs_descriptor)) {
BX_ERROR(("interrupt(): segment not present"));
exception(BX_NP_EXCEPTION, cs_selector.value & 0xfffc);
}
// if code segment is non-conforming and DPL < CPL then
// INTERRUPT TO INNER PRIVILEGE
if(IS_CODE_SEGMENT_NON_CONFORMING(cs_descriptor.type) && cs_descriptor.dpl < CPL)
{
Bit16u old_SS, old_CS, SS_for_cpl_x;
Bit32u ESP_for_cpl_x, old_EIP, old_ESP;
bx_descriptor_t ss_descriptor;
bx_selector_t ss_selector;
int is_v8086_mode = v8086_mode();
BX_DEBUG(("interrupt(): INTERRUPT TO INNER PRIVILEGE"));
// check selector and descriptor for new stack in current TSS
get_SS_ESP_from_TSS(cs_descriptor.dpl,
&SS_for_cpl_x, &ESP_for_cpl_x);
if (is_v8086_mode && cs_descriptor.dpl != 0) {
// if code segment DPL != 0 then #GP(new code segment selector)
BX_ERROR(("interrupt(): code segment DPL(%d) != 0 in v8086 mode", cs_descriptor.dpl));
exception(BX_GP_EXCEPTION, cs_selector.value & 0xfffc);
}
// Selector must be non-null else #TS(EXT)
if ((SS_for_cpl_x & 0xfffc) == 0) {
BX_ERROR(("interrupt(): SS selector null"));
exception(BX_TS_EXCEPTION, 0); /* TS(ext) */
}
// selector index must be within its descriptor table limits
// else #TS(SS selector + EXT)
parse_selector(SS_for_cpl_x, &ss_selector);
// fetch 2 dwords of descriptor; call handles out of limits checks
fetch_raw_descriptor(&ss_selector, &dword1, &dword2, BX_TS_EXCEPTION);
parse_descriptor(dword1, dword2, &ss_descriptor);
// selector rpl must = dpl of code segment,
// else #TS(SS selector + ext)
if (ss_selector.rpl != cs_descriptor.dpl) {
BX_ERROR(("interrupt(): SS.rpl != CS.dpl"));
exception(BX_TS_EXCEPTION, SS_for_cpl_x & 0xfffc);
}
// stack seg DPL must = DPL of code segment,
// else #TS(SS selector + ext)
if (ss_descriptor.dpl != cs_descriptor.dpl) {
BX_ERROR(("interrupt(): SS.dpl != CS.dpl"));
exception(BX_TS_EXCEPTION, SS_for_cpl_x & 0xfffc);
}
// descriptor must indicate writable data segment,
// else #TS(SS selector + EXT)
if (ss_descriptor.valid==0 || ss_descriptor.segment==0 ||
IS_CODE_SEGMENT(ss_descriptor.type) ||
!IS_DATA_SEGMENT_WRITEABLE(ss_descriptor.type))
{
BX_ERROR(("interrupt(): SS is not writable data segment"));
exception(BX_TS_EXCEPTION, SS_for_cpl_x & 0xfffc);
}
// seg must be present, else #SS(SS selector + ext)
if (! IS_PRESENT(ss_descriptor)) {
BX_ERROR(("interrupt(): SS not present"));
exception(BX_SS_EXCEPTION, SS_for_cpl_x & 0xfffc);
}
// IP must be within CS segment boundaries, else #GP(0)
if (gate_dest_offset > cs_descriptor.u.segment.limit_scaled) {
BX_ERROR(("interrupt(): gate EIP > CS.limit"));
exception(BX_GP_EXCEPTION, 0);
}
old_ESP = ESP;
old_SS = BX_CPU_THIS_PTR sregs[BX_SEG_REG_SS].selector.value;
old_EIP = EIP;
old_CS = BX_CPU_THIS_PTR sregs[BX_SEG_REG_CS].selector.value;
// Prepare new stack segment
bx_segment_reg_t new_stack;
new_stack.selector = ss_selector;
new_stack.cache = ss_descriptor;
new_stack.selector.rpl = cs_descriptor.dpl;
// add cpl to the selector value
new_stack.selector.value = (0xfffc & new_stack.selector.value) |
new_stack.selector.rpl;
if (ss_descriptor.u.segment.d_b) {
Bit32u temp_ESP = ESP_for_cpl_x;
if (is_v8086_mode)
{
if (gate_descriptor.type>=14) { // 386 int/trap gate
write_new_stack_dword_32(&new_stack, temp_ESP-4, cs_descriptor.dpl,
BX_CPU_THIS_PTR sregs[BX_SEG_REG_GS].selector.value);
write_new_stack_dword_32(&new_stack, temp_ESP-8, cs_descriptor.dpl,
BX_CPU_THIS_PTR sregs[BX_SEG_REG_FS].selector.value);
write_new_stack_dword_32(&new_stack, temp_ESP-12, cs_descriptor.dpl,
BX_CPU_THIS_PTR sregs[BX_SEG_REG_DS].selector.value);
write_new_stack_dword_32(&new_stack, temp_ESP-16, cs_descriptor.dpl,
BX_CPU_THIS_PTR sregs[BX_SEG_REG_ES].selector.value);
temp_ESP -= 16;
}
else {
write_new_stack_word_32(&new_stack, temp_ESP-2, cs_descriptor.dpl,
BX_CPU_THIS_PTR sregs[BX_SEG_REG_GS].selector.value);
write_new_stack_word_32(&new_stack, temp_ESP-4, cs_descriptor.dpl,
BX_CPU_THIS_PTR sregs[BX_SEG_REG_FS].selector.value);
write_new_stack_word_32(&new_stack, temp_ESP-6, cs_descriptor.dpl,
BX_CPU_THIS_PTR sregs[BX_SEG_REG_DS].selector.value);
write_new_stack_word_32(&new_stack, temp_ESP-8, cs_descriptor.dpl,
BX_CPU_THIS_PTR sregs[BX_SEG_REG_ES].selector.value);
temp_ESP -= 8;
}
}
if (gate_descriptor.type>=14) { // 386 int/trap gate
// push long pointer to old stack onto new stack
write_new_stack_dword_32(&new_stack, temp_ESP-4, cs_descriptor.dpl, old_SS);
write_new_stack_dword_32(&new_stack, temp_ESP-8, cs_descriptor.dpl, old_ESP);
write_new_stack_dword_32(&new_stack, temp_ESP-12, cs_descriptor.dpl, read_eflags());
write_new_stack_dword_32(&new_stack, temp_ESP-16, cs_descriptor.dpl, old_CS);
write_new_stack_dword_32(&new_stack, temp_ESP-20, cs_descriptor.dpl, old_EIP);
temp_ESP -= 20;
if (push_error) {
temp_ESP -= 4;
write_new_stack_dword_32(&new_stack, temp_ESP, cs_descriptor.dpl, error_code);
}
}
else { // 286 int/trap gate
// push long pointer to old stack onto new stack
write_new_stack_word_32(&new_stack, temp_ESP-2, cs_descriptor.dpl, old_SS);
write_new_stack_word_32(&new_stack, temp_ESP-4, cs_descriptor.dpl, (Bit16u) old_ESP);
write_new_stack_word_32(&new_stack, temp_ESP-6, cs_descriptor.dpl, (Bit16u) read_eflags());
write_new_stack_word_32(&new_stack, temp_ESP-8, cs_descriptor.dpl, old_CS);
write_new_stack_word_32(&new_stack, temp_ESP-10, cs_descriptor.dpl, (Bit16u) old_EIP);
temp_ESP -= 10;
if (push_error) {
temp_ESP -= 2;
write_new_stack_word_32(&new_stack, temp_ESP, cs_descriptor.dpl, error_code);
}
}
ESP = temp_ESP;
}
else {
Bit16u temp_SP = (Bit16u) ESP_for_cpl_x;
if (is_v8086_mode)
{
if (gate_descriptor.type>=14) { // 386 int/trap gate
write_new_stack_dword_32(&new_stack, (Bit16u)(temp_SP-4), cs_descriptor.dpl,
BX_CPU_THIS_PTR sregs[BX_SEG_REG_GS].selector.value);
write_new_stack_dword_32(&new_stack, (Bit16u)(temp_SP-8), cs_descriptor.dpl,
BX_CPU_THIS_PTR sregs[BX_SEG_REG_FS].selector.value);
write_new_stack_dword_32(&new_stack, (Bit16u)(temp_SP-12), cs_descriptor.dpl,
BX_CPU_THIS_PTR sregs[BX_SEG_REG_DS].selector.value);
write_new_stack_dword_32(&new_stack, (Bit16u)(temp_SP-16), cs_descriptor.dpl,
BX_CPU_THIS_PTR sregs[BX_SEG_REG_ES].selector.value);
temp_SP -= 16;
}
else {
write_new_stack_word_32(&new_stack, (Bit16u)(temp_SP-2), cs_descriptor.dpl,
BX_CPU_THIS_PTR sregs[BX_SEG_REG_GS].selector.value);
write_new_stack_word_32(&new_stack, (Bit16u)(temp_SP-4), cs_descriptor.dpl,
BX_CPU_THIS_PTR sregs[BX_SEG_REG_FS].selector.value);
write_new_stack_word_32(&new_stack, (Bit16u)(temp_SP-6), cs_descriptor.dpl,
BX_CPU_THIS_PTR sregs[BX_SEG_REG_DS].selector.value);
write_new_stack_word_32(&new_stack, (Bit16u)(temp_SP-8), cs_descriptor.dpl,
BX_CPU_THIS_PTR sregs[BX_SEG_REG_ES].selector.value);
temp_SP -= 8;
}
}
if (gate_descriptor.type>=14) { // 386 int/trap gate
// push long pointer to old stack onto new stack
write_new_stack_dword_32(&new_stack, (Bit16u)(temp_SP-4), cs_descriptor.dpl, old_SS);
write_new_stack_dword_32(&new_stack, (Bit16u)(temp_SP-8), cs_descriptor.dpl, old_ESP);
write_new_stack_dword_32(&new_stack, (Bit16u)(temp_SP-12), cs_descriptor.dpl, read_eflags());
write_new_stack_dword_32(&new_stack, (Bit16u)(temp_SP-16), cs_descriptor.dpl, old_CS);
write_new_stack_dword_32(&new_stack, (Bit16u)(temp_SP-20), cs_descriptor.dpl, old_EIP);
temp_SP -= 20;
if (push_error) {
temp_SP -= 4;
write_new_stack_dword_32(&new_stack, temp_SP, cs_descriptor.dpl, error_code);
}
}
else { // 286 int/trap gate
// push long pointer to old stack onto new stack
write_new_stack_word_32(&new_stack, (Bit16u)(temp_SP-2), cs_descriptor.dpl, old_SS);
write_new_stack_word_32(&new_stack, (Bit16u)(temp_SP-4), cs_descriptor.dpl, (Bit16u) old_ESP);
write_new_stack_word_32(&new_stack, (Bit16u)(temp_SP-6), cs_descriptor.dpl, (Bit16u) read_eflags());
write_new_stack_word_32(&new_stack, (Bit16u)(temp_SP-8), cs_descriptor.dpl, old_CS);
write_new_stack_word_32(&new_stack, (Bit16u)(temp_SP-10), cs_descriptor.dpl, (Bit16u) old_EIP);
temp_SP -= 10;
if (push_error) {
temp_SP -= 2;
write_new_stack_word_32(&new_stack, temp_SP, cs_descriptor.dpl, error_code);
}
}
SP = temp_SP;
}
// load new CS:eIP values from gate
// set CPL to new code segment DPL
// set RPL of CS to CPL
load_cs(&cs_selector, &cs_descriptor, cs_descriptor.dpl);
// load new SS:eSP values from TSS
load_ss(&ss_selector, &ss_descriptor, cs_descriptor.dpl);
if (is_v8086_mode)
{
BX_CPU_THIS_PTR sregs[BX_SEG_REG_GS].cache.valid = 0;
BX_CPU_THIS_PTR sregs[BX_SEG_REG_GS].selector.value = 0;
BX_CPU_THIS_PTR sregs[BX_SEG_REG_FS].cache.valid = 0;
BX_CPU_THIS_PTR sregs[BX_SEG_REG_FS].selector.value = 0;
BX_CPU_THIS_PTR sregs[BX_SEG_REG_DS].cache.valid = 0;
BX_CPU_THIS_PTR sregs[BX_SEG_REG_DS].selector.value = 0;
BX_CPU_THIS_PTR sregs[BX_SEG_REG_ES].cache.valid = 0;
BX_CPU_THIS_PTR sregs[BX_SEG_REG_ES].selector.value = 0;
}
}
else
{
BX_DEBUG(("interrupt(): INTERRUPT TO SAME PRIVILEGE"));
if (v8086_mode() && (IS_CODE_SEGMENT_CONFORMING(cs_descriptor.type) || cs_descriptor.dpl != 0)) {
// if code segment DPL != 0 then #GP(new code segment selector)
BX_ERROR(("interrupt(): code segment conforming or DPL(%d) != 0 in v8086 mode", cs_descriptor.dpl));
exception(BX_GP_EXCEPTION, cs_selector.value & 0xfffc);
}
// EIP must be in CS limit else #GP(0)
if (gate_dest_offset > cs_descriptor.u.segment.limit_scaled) {
BX_ERROR(("interrupt(): IP > CS descriptor limit"));
exception(BX_GP_EXCEPTION, 0);
}
// push flags onto stack
// push current CS selector onto stack
// push return offset onto stack
if (gate_descriptor.type >= 14) { // 386 gate
push_32(read_eflags());
push_32(BX_CPU_THIS_PTR sregs[BX_SEG_REG_CS].selector.value);
push_32(EIP);
if (push_error)
push_32(error_code);
}
else { // 286 gate
push_16((Bit16u) read_eflags());
push_16(BX_CPU_THIS_PTR sregs[BX_SEG_REG_CS].selector.value);
push_16(IP);
if (push_error)
push_16(error_code);
}
// load CS:IP from gate
// load CS descriptor
// set the RPL field of CS to CPL
load_cs(&cs_selector, &cs_descriptor, CPL);
}
EIP = gate_dest_offset;
// if interrupt gate then set IF to 0
if (!(gate_descriptor.type & 1)) // even is int-gate
BX_CPU_THIS_PTR clear_IF();
BX_CPU_THIS_PTR clear_TF();
BX_CPU_THIS_PTR clear_NT();
BX_CPU_THIS_PTR clear_VM();
BX_CPU_THIS_PTR clear_RF();
return;
default:
BX_PANIC(("bad descriptor type in interrupt()!"));
break;
}
}
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);
#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
bx_descriptor_t gate_descriptor = cs_descriptor;
bx_selector_t gate_selector = cs_selector;
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"));
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"));
exception(BX_GP_EXCEPTION, cs_raw & 0xfffc, 0);
}
#if BX_SUPPORT_X86_64
if (long_mode()) {
// call gate type is higher priority than non-present bit check
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
#endif
{
switch (gate_descriptor.type) {
case BX_SYS_SEGMENT_AVAIL_286_TSS:
case BX_SYS_SEGMENT_AVAIL_386_TSS:
case BX_TASK_GATE:
case BX_286_CALL_GATE:
case BX_386_CALL_GATE:
break;
default:
BX_ERROR(("call_protected(): gate.type(%u) unsupported", (unsigned) gate_descriptor.type));
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 not present"));
exception(BX_NP_EXCEPTION, cs_raw & 0xfffc, 0);
}
#if BX_SUPPORT_X86_64
if (long_mode()) {
call_gate64(&gate_selector);
return;
}
#endif
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"));
// 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_GP_EXCEPTION, raw_tss_selector & 0xfffc, 0);
}
// index must be within GDT limits else #TS(TSS selector)
fetch_raw_descriptor(&tss_selector, &dword1, &dword2, BX_GP_EXCEPTION);
parse_descriptor(dword1, dword2, &tss_descriptor);
// descriptor AR byte must specify available TSS
// else #GP(TSS selector)
if (tss_descriptor.valid==0 || tss_descriptor.segment) {
BX_ERROR(("call_protected: TSS selector points to bad TSS"));
exception(BX_GP_EXCEPTION, raw_tss_selector & 0xfffc, 0);
}
if (tss_descriptor.type!=BX_SYS_SEGMENT_AVAIL_286_TSS &&
tss_descriptor.type!=BX_SYS_SEGMENT_AVAIL_386_TSS)
{
BX_ERROR(("call_protected: TSS selector points to bad TSS"));
exception(BX_GP_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
BX_DEBUG(("call_protected: call gate"));
dest_selector = gate_descriptor.u.gate.dest_selector;
new_EIP = gate_descriptor.u.gate.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 ||
IS_DATA_SEGMENT(cs_descriptor.type) ||
cs_descriptor.dpl > CPL)
{
BX_ERROR(("call_protected: selected descriptor is not code"));
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);
}
// CALL GATE TO MORE PRIVILEGE
// if non-conforming code segment and DPL < CPL then
if (IS_CODE_SEGMENT_NON_CONFORMING(cs_descriptor.type) && (cs_descriptor.dpl < CPL))
{
Bit16u SS_for_cpl_x;
Bit32u ESP_for_cpl_x;
bx_selector_t ss_selector;
bx_descriptor_t ss_descriptor;
Bit16u return_SS, return_CS;
Bit32u return_ESP, return_EIP;
Bit16u parameter_word[32];
Bit32u parameter_dword[32];
BX_DEBUG(("CALL GATE TO MORE PRIVILEGE LEVEL"));
// get new SS selector for new privilege level from TSS
get_SS_ESP_from_TSS(cs_descriptor.dpl, &SS_for_cpl_x, &ESP_for_cpl_x);
// check selector & descriptor for new SS:
// selector must not be null, else #TS(0)
if ((SS_for_cpl_x & 0xfffc) == 0) {
BX_ERROR(("call_protected: new SS null"));
exception(BX_TS_EXCEPTION, 0, 0);
}
// 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);
// selector's RPL must equal DPL of code segment,
// else #TS(SS selector)
if (ss_selector.rpl != cs_descriptor.dpl) {
BX_ERROR(("call_protected: SS selector.rpl != CS descr.dpl"));
exception(BX_TS_EXCEPTION, SS_for_cpl_x & 0xfffc, 0);
}
// 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);
}
// descriptor must indicate writable data segment,
// else #TS(SS selector)
if (ss_descriptor.valid==0 || ss_descriptor.segment==0 ||
IS_CODE_SEGMENT(ss_descriptor.type) ||
!IS_DATA_SEGMENT_WRITEABLE(ss_descriptor.type))
{
BX_ERROR(("call_protected: ss descriptor is not writable data seg"));
exception(BX_TS_EXCEPTION, SS_for_cpl_x & 0xfffc, 0);
}
// 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);
}
// get word count from call gate, mask to 5 bits
unsigned param_count = gate_descriptor.u.gate.param_count & 0x1f;
// 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;
// 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++) {
parameter_word[i] = read_virtual_word(BX_SEG_REG_SS, return_ESP + i*2);
}
}
else {
for (unsigned i=0; i<param_count; i++) {
parameter_dword[i] = read_virtual_dword(BX_SEG_REG_SS, return_ESP + i*4);
}
}
// Prepare new stack segment
bx_segment_reg_t new_stack;
new_stack.selector = ss_selector;
new_stack.cache = ss_descriptor;
new_stack.selector.rpl = cs_descriptor.dpl;
// add cpl to the selector value
new_stack.selector.value = (0xfffc & new_stack.selector.value) |
new_stack.selector.rpl;
/* load new SS:SP value from TSS */
if (ss_descriptor.u.segment.d_b) {
Bit32u temp_ESP = ESP_for_cpl_x;
// push pointer of old stack onto new stack
if (gate_descriptor.type==BX_386_CALL_GATE) {
write_new_stack_dword_32(&new_stack, temp_ESP-4, cs_descriptor.dpl, return_SS);
write_new_stack_dword_32(&new_stack, temp_ESP-8, cs_descriptor.dpl, return_ESP);
temp_ESP -= 8;
for (unsigned i=param_count; i>0; i--) {
temp_ESP -= 4;
write_new_stack_dword_32(&new_stack, temp_ESP, cs_descriptor.dpl, parameter_dword[i-1]);
}
// push return address onto new stack
write_new_stack_dword_32(&new_stack, temp_ESP-4, cs_descriptor.dpl, return_CS);
write_new_stack_dword_32(&new_stack, temp_ESP-8, cs_descriptor.dpl, return_EIP);
temp_ESP -= 8;
}
else {
write_new_stack_word_32(&new_stack, temp_ESP-2, cs_descriptor.dpl, return_SS);
write_new_stack_word_32(&new_stack, temp_ESP-4, cs_descriptor.dpl, (Bit16u) return_ESP);
temp_ESP -= 4;
for (unsigned i=param_count; i>0; i--) {
temp_ESP -= 2;
write_new_stack_word_32(&new_stack, temp_ESP, cs_descriptor.dpl, parameter_word[i-1]);
}
// push return address onto new stack
write_new_stack_word_32(&new_stack, temp_ESP-2, cs_descriptor.dpl, return_CS);
write_new_stack_word_32(&new_stack, temp_ESP-4, cs_descriptor.dpl, (Bit16u) return_EIP);
temp_ESP -= 4;
}
ESP = temp_ESP;
}
else {
Bit16u temp_SP = (Bit16u) ESP_for_cpl_x;
// push pointer of old stack onto new stack
if (gate_descriptor.type==BX_386_CALL_GATE) {
write_new_stack_dword_32(&new_stack, (Bit16u)(temp_SP-4), cs_descriptor.dpl, return_SS);
write_new_stack_dword_32(&new_stack, (Bit16u)(temp_SP-8), cs_descriptor.dpl, return_ESP);
temp_SP -= 8;
for (unsigned i=param_count; i>0; i--) {
temp_SP -= 4;
write_new_stack_dword_32(&new_stack, temp_SP, cs_descriptor.dpl, parameter_dword[i-1]);
}
// push return address onto new stack
write_new_stack_dword_32(&new_stack, (Bit16u)(temp_SP-4), cs_descriptor.dpl, return_CS);
write_new_stack_dword_32(&new_stack, (Bit16u)(temp_SP-8), cs_descriptor.dpl, return_EIP);
temp_SP -= 8;
}
else {
write_new_stack_word_32(&new_stack, (Bit16u)(temp_SP-2), cs_descriptor.dpl, return_SS);
write_new_stack_word_32(&new_stack, (Bit16u)(temp_SP-4), cs_descriptor.dpl, (Bit16u) return_ESP);
temp_SP -= 4;
for (unsigned i=param_count; i>0; i--) {
temp_SP -= 2;
write_new_stack_word_32(&new_stack, temp_SP, cs_descriptor.dpl, parameter_word[i-1]);
}
// push return address onto new stack
write_new_stack_word_32(&new_stack, (Bit16u)(temp_SP-2), cs_descriptor.dpl, return_CS);
write_new_stack_word_32(&new_stack, (Bit16u)(temp_SP-4), cs_descriptor.dpl, (Bit16u) return_EIP);
temp_SP -= 4;
}
SP = temp_SP;
}
// 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);
}
/* load SS descriptor */
load_ss(&ss_selector, &ss_descriptor, cs_descriptor.dpl);
/* 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;
}
else // CALL GATE TO SAME PRIVILEGE
{
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
branch_far32(&cs_selector, &cs_descriptor, new_EIP, CPL);
}
return;
default: // can't get here
BX_PANIC(("call_protected: gate type %u unsupported", (unsigned) cs_descriptor.type));
exception(BX_GP_EXCEPTION, cs_raw & 0xfffc, 0);
}
}
}
void BX_CPP_AttrRegparmN(1) BX_CPU_C::call_gate(bx_descriptor_t *gate_descriptor)
{
bx_selector_t cs_selector;
Bit32u dword1, dword2;
bx_descriptor_t cs_descriptor;
// examine code segment selector in call gate descriptor
BX_DEBUG(("call_protected: call gate"));
Bit16u dest_selector = gate_descriptor->u.gate.dest_selector;
Bit32u new_EIP = gate_descriptor->u.gate.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);
}
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 ||
IS_DATA_SEGMENT(cs_descriptor.type) || cs_descriptor.dpl > CPL)
{
BX_ERROR(("call_protected: selected descriptor is not code"));
exception(BX_GP_EXCEPTION, dest_selector & 0xfffc);
}
// 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);
}
// CALL GATE TO MORE PRIVILEGE
// if non-conforming code segment and DPL < CPL then
if (IS_CODE_SEGMENT_NON_CONFORMING(cs_descriptor.type) && (cs_descriptor.dpl < CPL))
{
Bit16u SS_for_cpl_x;
Bit32u ESP_for_cpl_x;
bx_selector_t ss_selector;
bx_descriptor_t ss_descriptor;
Bit16u return_SS, return_CS;
Bit32u return_ESP, return_EIP;
BX_DEBUG(("CALL GATE TO MORE PRIVILEGE LEVEL"));
// get new SS selector for new privilege level from TSS
get_SS_ESP_from_TSS(cs_descriptor.dpl, &SS_for_cpl_x, &ESP_for_cpl_x);
// check selector & descriptor for new SS:
// selector must not be null, else #TS(0)
if ((SS_for_cpl_x & 0xfffc) == 0) {
BX_ERROR(("call_protected: new SS null"));
exception(BX_TS_EXCEPTION, 0);
}
// 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);
// selector's RPL must equal DPL of code segment,
// else #TS(SS selector)
if (ss_selector.rpl != cs_descriptor.dpl) {
BX_ERROR(("call_protected: SS selector.rpl != CS descr.dpl"));
exception(BX_TS_EXCEPTION, SS_for_cpl_x & 0xfffc);
}
// 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);
}
// descriptor must indicate writable data segment,
// else #TS(SS selector)
if (ss_descriptor.valid==0 || ss_descriptor.segment==0 ||
IS_CODE_SEGMENT(ss_descriptor.type) || !IS_DATA_SEGMENT_WRITEABLE(ss_descriptor.type))
{
BX_ERROR(("call_protected: ss descriptor is not writable data seg"));
exception(BX_TS_EXCEPTION, SS_for_cpl_x & 0xfffc);
}
// 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);
}
// get word count from call gate, mask to 5 bits
unsigned param_count = gate_descriptor->u.gate.param_count & 0x1f;
// 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;
// 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;
// Prepare new stack segment
bx_segment_reg_t new_stack;
new_stack.selector = ss_selector;
new_stack.cache = ss_descriptor;
new_stack.selector.rpl = cs_descriptor.dpl;
// add cpl to the selector value
new_stack.selector.value = (0xfffc & new_stack.selector.value) |
new_stack.selector.rpl;
/* load new SS:SP value from TSS */
if (ss_descriptor.u.segment.d_b) {
Bit32u temp_ESP = ESP_for_cpl_x;
// push pointer of old stack onto new stack
if (gate_descriptor->type==BX_386_CALL_GATE) {
write_new_stack_dword_32(&new_stack, temp_ESP-4, cs_descriptor.dpl, return_SS);
write_new_stack_dword_32(&new_stack, temp_ESP-8, cs_descriptor.dpl, return_ESP);
temp_ESP -= 8;
for (unsigned n=param_count; n>0; n--) {
temp_ESP -= 4;
Bit32u param = read_virtual_dword_32(BX_SEG_REG_SS, return_ESP + (n-1)*4);
write_new_stack_dword_32(&new_stack, temp_ESP, cs_descriptor.dpl, param);
}
// push return address onto new stack
write_new_stack_dword_32(&new_stack, temp_ESP-4, cs_descriptor.dpl, return_CS);
write_new_stack_dword_32(&new_stack, temp_ESP-8, cs_descriptor.dpl, return_EIP);
temp_ESP -= 8;
}
else {
write_new_stack_word_32(&new_stack, temp_ESP-2, cs_descriptor.dpl, return_SS);
write_new_stack_word_32(&new_stack, temp_ESP-4, cs_descriptor.dpl, (Bit16u) return_ESP);
temp_ESP -= 4;
for (unsigned n=param_count; n>0; n--) {
temp_ESP -= 2;
Bit16u param = read_virtual_word_32(BX_SEG_REG_SS, return_ESP + (n-1)*2);
write_new_stack_word_32(&new_stack, temp_ESP, cs_descriptor.dpl, param);
}
// push return address onto new stack
write_new_stack_word_32(&new_stack, temp_ESP-2, cs_descriptor.dpl, return_CS);
write_new_stack_word_32(&new_stack, temp_ESP-4, cs_descriptor.dpl, (Bit16u) return_EIP);
temp_ESP -= 4;
}
ESP = temp_ESP;
}
else {
Bit16u temp_SP = (Bit16u) ESP_for_cpl_x;
// push pointer of old stack onto new stack
if (gate_descriptor->type==BX_386_CALL_GATE) {
write_new_stack_dword_32(&new_stack, (Bit16u)(temp_SP-4), cs_descriptor.dpl, return_SS);
write_new_stack_dword_32(&new_stack, (Bit16u)(temp_SP-8), cs_descriptor.dpl, return_ESP);
temp_SP -= 8;
for (unsigned n=param_count; n>0; n--) {
temp_SP -= 4;
Bit32u param = read_virtual_dword_32(BX_SEG_REG_SS, return_ESP + (n-1)*4);
write_new_stack_dword_32(&new_stack, temp_SP, cs_descriptor.dpl, param);
}
// push return address onto new stack
write_new_stack_dword_32(&new_stack, (Bit16u)(temp_SP-4), cs_descriptor.dpl, return_CS);
write_new_stack_dword_32(&new_stack, (Bit16u)(temp_SP-8), cs_descriptor.dpl, return_EIP);
temp_SP -= 8;
}
else {
write_new_stack_word_32(&new_stack, (Bit16u)(temp_SP-2), cs_descriptor.dpl, return_SS);
write_new_stack_word_32(&new_stack, (Bit16u)(temp_SP-4), cs_descriptor.dpl, (Bit16u) return_ESP);
temp_SP -= 4;
for (unsigned n=param_count; n>0; n--) {
temp_SP -= 2;
Bit16u param = read_virtual_word_32(BX_SEG_REG_SS, return_ESP + (n-1)*2);
write_new_stack_word_32(&new_stack, temp_SP, cs_descriptor.dpl, param);
}
// push return address onto new stack
write_new_stack_word_32(&new_stack, (Bit16u)(temp_SP-2), cs_descriptor.dpl, return_CS);
write_new_stack_word_32(&new_stack, (Bit16u)(temp_SP-4), cs_descriptor.dpl, (Bit16u) return_EIP);
temp_SP -= 4;
}
SP = temp_SP;
}
// 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);
}
/* load SS descriptor */
load_ss(&ss_selector, &ss_descriptor, cs_descriptor.dpl);
/* 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;
}
else // CALL GATE TO SAME PRIVILEGE
{
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
branch_far32(&cs_selector, &cs_descriptor, new_EIP, CPL);
}
}
void
bx_cpu_c::PUSH_RX(BxInstruction_t *i)
{
push_16( bx_cpu. gen_reg[i->b1 & 0x07].word.rx );
}
