///////////////////////////////////////////////////////////////////////// // $Id: exception.cc,v 1.51 2005-03-30 20:52:49 sshwarts Exp $ ///////////////////////////////////////////////////////////////////////// // // 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" #include "iodev/iodev.h" #define LOG_THIS BX_CPU_THIS_PTR /* Exception classes. These are used as indexes into the 'is_exception_OK' * array below, and are stored in the 'exception' array also */ #define BX_ET_BENIGN 0 #define BX_ET_CONTRIBUTORY 1 #define BX_ET_PAGE_FAULT 2 #define BX_ET_DOUBLE_FAULT 10 static const bx_bool is_exception_OK[3][3] = { { 1, 1, 1 }, /* 1st exception is BENIGN */ { 1, 0, 1 }, /* 1st exception is CONTRIBUTORY */ { 1, 0, 0 } /* 1st exception is PAGE_FAULT */ }; void BX_CPU_C::interrupt(Bit8u vector, bx_bool is_INT, bx_bool is_error_code, Bit16u error_code) { #if BX_DEBUGGER if (bx_guard.special_unwind_stack) { BX_INFO (("interrupt() returning early because special_unwind_stack is set")); return; } BX_CPU_THIS_PTR show_flag |= Flag_intsig; #if BX_DEBUG_LINUX if (bx_dbg.linux_syscall) { if (vector == 0x80) bx_dbg_linux_syscall (); } #endif #endif BX_DEBUG(("interrupt(): vector = %u, INT = %u, EXT = %u", (unsigned) vector, (unsigned) is_INT, (unsigned) BX_CPU_THIS_PTR EXT)); BX_INSTR_INTERRUPT(BX_CPU_ID, vector); invalidate_prefetch_q(); // Discard any traps and inhibits for new context; traps will // resume upon return. BX_CPU_THIS_PTR debug_trap = 0; BX_CPU_THIS_PTR inhibit_mask = 0; #if BX_CPU_LEVEL >= 2 BX_CPU_THIS_PTR save_cs = BX_CPU_THIS_PTR sregs[BX_SEG_REG_CS]; BX_CPU_THIS_PTR save_ss = BX_CPU_THIS_PTR sregs[BX_SEG_REG_SS]; BX_CPU_THIS_PTR save_eip = EIP; BX_CPU_THIS_PTR save_esp = ESP; #if BX_SUPPORT_X86_64 if (BX_CPU_THIS_PTR msr.lma) { // long mode interrupt Bit64u idtindex; Bit32u dword1, dword2, dword3; bx_descriptor_t gate_descriptor, cs_descriptor; bx_selector_t cs_selector; Bit16u gate_dest_selector; Bit64u gate_dest_offset; unsigned ist; // interrupt vector must be within IDT table limits, // else #GP(vector number*16 + 2 + EXT) idtindex = vector*16; if ( (idtindex + 15) > BX_CPU_THIS_PTR idtr.limit) { BX_ERROR(("IDT.limit = %04x", (unsigned) BX_CPU_THIS_PTR idtr.limit)); BX_ERROR(("IDT.base = %06x", (unsigned) BX_CPU_THIS_PTR idtr.base)); BX_ERROR(("interrupt vector must be within IDT table limits")); BX_ERROR(("long mode interrupt(): vector > idtr.limit")); exception(BX_GP_EXCEPTION, vector*16 + 2, 0); } // descriptor AR byte must indicate interrupt gate, trap gate, // or task gate, else #GP(vector*8 + 2 + EXT) idtindex += BX_CPU_THIS_PTR idtr.base; access_linear(idtindex, 4, 0, BX_READ, &dword1); access_linear(idtindex + 4, 4, 0, BX_READ, &dword2); access_linear(idtindex + 8, 4, 0, BX_READ, &dword3); parse_descriptor(dword1, dword2, &gate_descriptor); if ((gate_descriptor.valid==0) || gate_descriptor.segment) { BX_ERROR(("long mode interrupt(): gate descriptor is not valid sys seg")); exception(BX_GP_EXCEPTION, vector*8 + 2, 0); } 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(("long mode interrupt(): gate.type(%u) != {5,6,7,14,15}", (unsigned) gate_descriptor.type)); exception(BX_GP_EXCEPTION, vector*8 + 2, 0); return; } // if software interrupt, then gate descripor DPL must be >= CPL, // else #GP(vector * 8 + 2 + EXT) if (is_INT && (gate_descriptor.dpl < CPL)) { BX_ERROR(("long mode interrupt(): is_INT && (dpl < CPL)")); exception(BX_GP_EXCEPTION, vector*8 + 2, 0); return; } // Gate must be present, else #NP(vector * 8 + 2 + EXT) if (gate_descriptor.p == 0) { BX_ERROR(("long mode interrupt(): p == 0")); exception(BX_NP_EXCEPTION, vector*8 + 2, 0); } gate_dest_selector = gate_descriptor.u.gate386.dest_selector; gate_dest_offset = ((Bit64u)dword3 << 32) + gate_descriptor.u.gate386.dest_offset; ist = gate_descriptor.u.gate386.dword_count & 0x7; // examine CS selector and descriptor given in gate descriptor // selector must be non-null else #GP(EXT) if ( (gate_dest_selector & 0xfffc) == 0 ) { BX_PANIC(("int_trap_gate(): selector null")); exception(BX_GP_EXCEPTION, 0, 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 || cs_descriptor.u.segment.executable==0 || cs_descriptor.dpl>CPL) { BX_ERROR(("long mode interrupt(): not code segment")); exception(BX_GP_EXCEPTION, cs_selector.value & 0xfffc, 0); } // check that it's a 64 bit segment if ( cs_descriptor.u.segment.l == 0 || cs_descriptor.u.segment.d_b == 1) { BX_ERROR(("long mode interrupt(): must be 64 bit segment")); exception(BX_GP_EXCEPTION, vector, 0); } // segment must be present, else #NP(selector + EXT) if ( cs_descriptor.p==0 ) { BX_ERROR(("long mode interrupt(): segment not present")); exception(BX_NP_EXCEPTION, cs_selector.value & 0xfffc, 0); } // if code segment is non-conforming and DPL < CPL then // INTERRUPT TO INNER PRIVILEGE: if ((cs_descriptor.u.segment.c_ed==0 && cs_descriptor.dpl 0)) { Bit16u old_SS; Bit64u RSP_for_cpl_x, old_RSP; bx_descriptor_t ss_descriptor; bx_selector_t ss_selector; BX_ERROR(("long mode interrupt(): INTERRUPT TO INNER PRIVILEGE")); // check selector and descriptor for new stack in current TSS if (ist > 0) { BX_ERROR(("long mode interrupt(): trap to IST, vector = %d\n",ist)); get_RSP_from_TSS(ist+3,&RSP_for_cpl_x); } else { get_RSP_from_TSS(cs_descriptor.dpl,&RSP_for_cpl_x); } // set up a null descriptor parse_selector(0,&ss_selector); parse_descriptor(0,0,&ss_descriptor); // 386 int/trap gate // new stack must have room for 40|48 bytes, else #SS(0) //if ( is_error_code ) // bytes = 48; //else // bytes = 40; old_SS = BX_CPU_THIS_PTR sregs[BX_SEG_REG_SS].selector.value; old_RSP = RSP; // load new RSP values from TSS int savemode = BX_CPU_THIS_PTR cpu_mode; BX_CPU_THIS_PTR cpu_mode = BX_MODE_LONG_64; // need to switch to 64 bit mode temporarily here. // this means that any exception after here might be delivered // a little insanely. Like faults are page faults.. load_ss(&ss_selector, &ss_descriptor, cs_descriptor.dpl); RSP = RSP_for_cpl_x; // load new CS:IP values from gate // set CPL to new code segment DPL CPL = cs_descriptor.dpl; // set RPL of CS to CPL // push long pointer to old stack onto new stack // align ESP push_64(old_SS); push_64(old_RSP); // push EFLAGS push_64(read_eflags()); // push long pointer to return address onto new stack push_64(BX_CPU_THIS_PTR sregs[BX_SEG_REG_CS].selector.value); push_64(RIP); if ( is_error_code ) push_64(error_code); BX_CPU_THIS_PTR cpu_mode = savemode; load_cs(&cs_selector, &cs_descriptor, cs_descriptor.dpl); RIP = gate_dest_offset; // if INTERRUPT GATE 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_VM (); BX_CPU_THIS_PTR clear_RF (); BX_CPU_THIS_PTR clear_NT (); return; } // if code segment is conforming OR code segment DPL = CPL then // INTERRUPT TO SAME PRIVILEGE LEVEL: if (cs_descriptor.u.segment.c_ed==1 || cs_descriptor.dpl==CPL) { BX_ERROR(("long mode interrupt(): INTERRUPT TO SAME PRIVILEGE")); Bit64u old_RSP = RSP; // align stack RSP = RSP & BX_CONST64(0xfffffffffffffff0); int savemode = BX_CPU_THIS_PTR cpu_mode; BX_CPU_THIS_PTR cpu_mode = BX_MODE_LONG_64; // push flags onto stack // push current CS selector onto stack // push return offset onto stack push_64(BX_CPU_THIS_PTR sregs[BX_SEG_REG_SS].selector.value); push_64(old_RSP); push_64(read_eflags()); push_64(BX_CPU_THIS_PTR sregs[BX_SEG_REG_CS].selector.value); push_64(RIP); if ( is_error_code ) push_64(error_code); BX_CPU_THIS_PTR cpu_mode = savemode; // load CS:IP from gate // load CS descriptor // set the RPL field of CS to CPL load_cs(&cs_selector, &cs_descriptor, CPL); RIP = 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_VM (); BX_CPU_THIS_PTR clear_RF (); BX_CPU_THIS_PTR clear_NT (); return; } // else #GP(CS selector + ext) BX_ERROR(("long mode interrupt(): bad descriptor")); BX_ERROR(("c_ed=%u, descriptor.dpl=%u, CPL=%u", (unsigned) cs_descriptor.u.segment.c_ed, (unsigned) cs_descriptor.dpl, (unsigned) CPL)); BX_ERROR(("cs.segment = %u", (unsigned) cs_descriptor.segment)); exception(BX_GP_EXCEPTION, cs_selector.value & 0xfffc, 0); } else #endif // #if BX_SUPPORT_X86_64 if(!real_mode()) { Bit32u dword1, dword2; 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 number*8 + 2 + EXT) if ( (vector*8 + 7) > BX_CPU_THIS_PTR idtr.limit) { BX_DEBUG(("IDT.limit = %04x", (unsigned) BX_CPU_THIS_PTR idtr.limit)); BX_DEBUG(("IDT.base = %06x", (unsigned) BX_CPU_THIS_PTR idtr.base)); BX_DEBUG(("interrupt vector must be within IDT table limits")); BX_DEBUG(("interrupt(): vector > idtr.limit")); exception(BX_GP_EXCEPTION, vector*8 + 2, 0); } // descriptor AR byte must indicate interrupt gate, trap gate, // or task gate, else #GP(vector*8 + 2 + EXT) access_linear(BX_CPU_THIS_PTR idtr.base + vector*8, 4, 0, BX_READ, &dword1); access_linear(BX_CPU_THIS_PTR idtr.base + vector*8 + 4, 4, 0, BX_READ, &dword2); parse_descriptor(dword1, dword2, &gate_descriptor); if ((gate_descriptor.valid==0) || gate_descriptor.segment) { BX_DEBUG(("interrupt(): gate descriptor is not valid sys seg")); exception(BX_GP_EXCEPTION, vector*8 + 2, 0); } 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_DEBUG(("interrupt(): gate.type(%u) != {5,6,7,14,15}", (unsigned) gate_descriptor.type)); exception(BX_GP_EXCEPTION, vector*8 + 2, 0); return; } // if software interrupt, then gate descripor DPL must be >= CPL, // else #GP(vector * 8 + 2 + EXT) if (is_INT && (gate_descriptor.dpl < CPL)) { BX_DEBUG(("interrupt(): is_INT && (dpl < CPL)")); exception(BX_GP_EXCEPTION, vector*8 + 2, 0); } // Gate must be present, else #NP(vector * 8 + 2 + EXT) if (gate_descriptor.p == 0) { BX_DEBUG(("interrupt(): gate not present")); exception(BX_NP_EXCEPTION, vector*8 + 2, 0); } 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 #TS(TSS selector) // +++ // 486/Pent books say #TSS(selector) // PPro+ says #GP(selector) if (tss_selector.ti) { BX_PANIC(("interrupt: tss_selector.ti=1")); exception(BX_TS_EXCEPTION, raw_tss_selector & 0xfffc, 0); return; } // index must be within GDT limits, else #TS(TSS selector) fetch_raw_descriptor(&tss_selector, &dword1, &dword2, BX_TS_EXCEPTION); // AR byte must specify available TSS, // else #TS(TSS selector) parse_descriptor(dword1, dword2, &tss_descriptor); if (tss_descriptor.valid==0 || tss_descriptor.segment) { BX_PANIC(("exception: TSS selector points to bad TSS")); exception(BX_TS_EXCEPTION, raw_tss_selector & 0xfffc, 0); return; } if (tss_descriptor.type!=9 && tss_descriptor.type!=1) { BX_INFO(("exception: TSS selector points to bad TSS")); exception(BX_TS_EXCEPTION, raw_tss_selector & 0xfffc, 0); return; } // TSS must be present, else #NP(TSS selector) // done in task_switch() // switch tasks with nesting to TSS task_switch(&tss_selector, &tss_descriptor, BX_TASK_FROM_CALL_OR_INT, dword1, dword2); // 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 //??? push_16 vs push_32 if ( is_error_code ) { //if (tss_descriptor.type==9) if (BX_CPU_THIS_PTR sregs[BX_SEG_REG_CS].cache.u.segment.d_b) 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(("exception(): EIP > CS.limit")); exception(BX_GP_EXCEPTION, 0, 0); } return; case BX_286_INTERRUPT_GATE: case BX_286_TRAP_GATE: case BX_386_INTERRUPT_GATE: case BX_386_TRAP_GATE: if ( gate_descriptor.type >= 14 ) { // 386 gate gate_dest_selector = gate_descriptor.u.gate386.dest_selector; gate_dest_offset = gate_descriptor.u.gate386.dest_offset; } else { // 286 gate gate_dest_selector = gate_descriptor.u.gate286.dest_selector; gate_dest_offset = gate_descriptor.u.gate286.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_PANIC(("int_trap_gate(): selector null")); exception(BX_GP_EXCEPTION, 0, 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 || cs_descriptor.u.segment.executable==0 || cs_descriptor.dpl>CPL ) { BX_DEBUG(("interrupt(): not code segment")); exception(BX_GP_EXCEPTION, cs_selector.value & 0xfffc, 0); } // segment must be present, else #NP(selector + EXT) if ( cs_descriptor.p==0 ) { BX_DEBUG(("interrupt(): segment not present")); exception(BX_NP_EXCEPTION, cs_selector.value & 0xfffc, 0); } // if code segment is non-conforming and DPL < CPL then // INTERRUPT TO INNER PRIVILEGE: if ( cs_descriptor.u.segment.c_ed==0 && cs_descriptor.dpl=14) { // 386 int/trap gate // new stack must have room for 20|24 bytes, else #SS(0) if ( is_error_code ) bytes = 24; else bytes = 20; if (is_v8086_mode) bytes += 16; } else { // new stack must have room for 10|12 bytes, else #SS(0) if ( is_error_code ) bytes = 12; else bytes = 10; if (is_v8086_mode) { bytes += 8; BX_PANIC(("interrupt: int/trap gate VM")); } } // new stack must have enough room, else #SS(seg selector) if ( !can_push(&ss_descriptor, ESP_for_cpl_x, bytes) ) { BX_DEBUG(("interrupt(): new stack doesn't have room for %u bytes", (unsigned) bytes)); exception(BX_SS_EXCEPTION, SS_for_cpl_x & 0xfffc, 0); } // IP must be within CS segment boundaries, else #GP(0) if (gate_dest_offset > cs_descriptor.u.segment.limit_scaled) { BX_DEBUG(("interrupt(): gate EIP > CS.limit")); exception(BX_GP_EXCEPTION, 0, 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; // load new SS:SP values from TSS load_ss(&ss_selector, &ss_descriptor, cs_descriptor.dpl); if (ss_descriptor.u.segment.d_b) ESP = ESP_for_cpl_x; else SP = ESP_for_cpl_x; // leave upper 16bits // load new CS:IP 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); EIP = gate_dest_offset; Bit32u eflags = read_eflags(); // if INTERRUPT GATE 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_VM (); BX_CPU_THIS_PTR clear_RF (); BX_CPU_THIS_PTR clear_NT (); if (is_v8086_mode) { if (gate_descriptor.type>=14) { // 386 int/trap gate push_32(BX_CPU_THIS_PTR sregs[BX_SEG_REG_GS].selector.value); push_32(BX_CPU_THIS_PTR sregs[BX_SEG_REG_FS].selector.value); push_32(BX_CPU_THIS_PTR sregs[BX_SEG_REG_DS].selector.value); push_32(BX_CPU_THIS_PTR sregs[BX_SEG_REG_ES].selector.value); } else { push_16(BX_CPU_THIS_PTR sregs[BX_SEG_REG_GS].selector.value); push_16(BX_CPU_THIS_PTR sregs[BX_SEG_REG_FS].selector.value); push_16(BX_CPU_THIS_PTR sregs[BX_SEG_REG_DS].selector.value); push_16(BX_CPU_THIS_PTR sregs[BX_SEG_REG_ES].selector.value); } 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; } if (gate_descriptor.type>=14) { // 386 int/trap gate // push long pointer to old stack onto new stack push_32(old_SS); push_32(old_ESP); // push EFLAGS push_32(eflags); // push long pointer to return address onto new stack push_32(old_CS); push_32(old_EIP); if ( is_error_code ) push_32(error_code); } else { // 286 int/trap gate // push long pointer to old stack onto new stack push_16(old_SS); push_16(old_ESP); // ignores upper 16bits // push FLAGS push_16(eflags); // ignores upper 16bits // push return address onto new stack push_16(old_CS); push_16(old_EIP); // ignores upper 16bits if ( is_error_code ) push_16(error_code); } return; } if (v8086_mode()) { // if code segment DPL != 0 then #GP(new code segment selector) exception(BX_GP_EXCEPTION, cs_selector.value & 0xfffc, 0); } // if code segment is conforming OR code segment DPL = CPL then // INTERRUPT TO SAME PRIVILEGE LEVEL: if ( cs_descriptor.u.segment.c_ed==1 || cs_descriptor.dpl==CPL ) { int bytes; Bit32u temp_ESP; if (BX_CPU_THIS_PTR sregs[BX_SEG_REG_SS].cache.u.segment.d_b) temp_ESP = ESP; else temp_ESP = SP; BX_DEBUG(("int_trap_gate286(): INTERRUPT TO SAME PRIVILEGE")); // Current stack limits must allow pushing 6|8 bytes, else #SS(0) if (gate_descriptor.type >= 14) { // 386 gate if ( is_error_code ) bytes = 16; else bytes = 12; } else { // 286 gate if ( is_error_code ) bytes = 8; else bytes = 6; } if (! can_push(&BX_CPU_THIS_PTR sregs[BX_SEG_REG_SS].cache, temp_ESP, bytes)) { BX_DEBUG(("interrupt(): stack doesn't have room")); exception(BX_SS_EXCEPTION, 0, 0); } // 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, 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 ( is_error_code ) push_32(error_code); } else { // 286 gate push_16(read_flags()); push_16(BX_CPU_THIS_PTR sregs[BX_SEG_REG_CS].selector.value); push_16(IP); if ( is_error_code ) 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; } // else #GP(CS selector + ext) BX_DEBUG(("interrupt: bad descriptor")); BX_DEBUG(("c_ed=%u, descriptor.dpl=%u, CPL=%u", (unsigned) cs_descriptor.u.segment.c_ed, (unsigned) cs_descriptor.dpl, (unsigned) CPL)); BX_DEBUG(("cs.segment = %u", (unsigned) cs_descriptor.segment)); exception(BX_GP_EXCEPTION, cs_selector.value & 0xfffc, 0); break; default: BX_PANIC(("bad descriptor type in interrupt()!")); break; } } else #endif { /* real mode */ 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(read_flags()); cs_selector = BX_CPU_THIS_PTR sregs[BX_SEG_REG_CS].selector.value; push_16(cs_selector); ip = EIP; push_16(ip); access_linear(BX_CPU_THIS_PTR idtr.base + 4 * vector, 2, 0, BX_READ, &ip); EIP = (Bit32u) ip; access_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 (); } } // vector: 0..255: vector in IDT // error_code: if exception generates and error, push this error code void BX_CPU_C::exception(unsigned vector, Bit16u error_code, bx_bool is_INT) { bx_bool push_error; Bit8u exception_type; unsigned prev_errno; invalidate_prefetch_q(); UNUSED(is_INT); #if BX_DEBUGGER if (bx_guard.special_unwind_stack) { BX_INFO (("exception() returning early because special_unwind_stack is set")); longjmp(BX_CPU_THIS_PTR jmp_buf_env, 1); // go back to main decode loop } #endif #if BX_EXTERNAL_DEBUGGER //trap_debugger(1); #endif BX_INSTR_EXCEPTION(BX_CPU_ID, vector); BX_DEBUG(("exception(%02x h)", (unsigned) vector)); // if not initial error, restore previous register values from // previous attempt to handle exception if (BX_CPU_THIS_PTR errorno) { BX_CPU_THIS_PTR sregs[BX_SEG_REG_CS] = BX_CPU_THIS_PTR save_cs; BX_CPU_THIS_PTR sregs[BX_SEG_REG_SS] = BX_CPU_THIS_PTR save_ss; EIP = BX_CPU_THIS_PTR save_eip; ESP = BX_CPU_THIS_PTR save_esp; } BX_CPU_THIS_PTR errorno++; if (BX_CPU_THIS_PTR errorno >= 3) { #if BX_RESET_ON_TRIPLE_FAULT BX_ERROR(("exception(): 3rd (%d) exception with no resolution, shutdown status is %02xh, resetting", vector, DEV_cmos_get_reg(0x0f))); bx_pc_system.Reset( BX_RESET_SOFTWARE ); #else BX_PANIC(("exception(): 3rd (%d) exception with no resolution", vector)); BX_ERROR(("WARNING: Any simulation after this point is completely bogus.")); #endif #if BX_DEBUGGER bx_guard.special_unwind_stack = true; #endif longjmp(BX_CPU_THIS_PTR jmp_buf_env, 1); // go back to main decode loop } /* careful not to get here with curr_exception[1]==DOUBLE_FAULT */ /* ...index on DOUBLE_FAULT below, will be out of bounds */ /* if 1st was a double fault (software INT?), then shutdown */ if ( (BX_CPU_THIS_PTR errorno==2) && (BX_CPU_THIS_PTR curr_exception[0]==BX_ET_DOUBLE_FAULT) ) { #if BX_RESET_ON_TRIPLE_FAULT BX_INFO(("exception(): triple fault encountered, shutdown status is %02xh, resetting", DEV_cmos_get_reg(0x0f))); bx_pc_system.Reset( BX_RESET_SOFTWARE ); #else BX_PANIC(("exception(): triple fault encountered")); BX_ERROR(("WARNING: Any simulation after this point is completely bogus.")); #endif #if BX_DEBUGGER bx_guard.special_unwind_stack = true; #endif longjmp(BX_CPU_THIS_PTR jmp_buf_env, 1); // go back to main decode loop } /* ??? this is not totally correct, should be done depending on * vector */ /* backup IP to value before error occurred */ EIP = BX_CPU_THIS_PTR prev_eip; ESP = BX_CPU_THIS_PTR prev_esp; // note: fault-class exceptions _except_ #DB set RF in // eflags image. switch (vector) { case 0: // DIV by 0 push_error = 0; exception_type = BX_ET_CONTRIBUTORY; BX_CPU_THIS_PTR assert_RF (); break; case 1: // debug exceptions push_error = 0; exception_type = BX_ET_BENIGN; break; case 2: // NMI push_error = 0; exception_type = BX_ET_BENIGN; break; case 3: // breakpoint push_error = 0; exception_type = BX_ET_BENIGN; break; case 4: // overflow push_error = 0; exception_type = BX_ET_BENIGN; break; case 5: // bounds check push_error = 0; exception_type = BX_ET_BENIGN; BX_CPU_THIS_PTR assert_RF (); break; case 6: // invalid opcode push_error = 0; exception_type = BX_ET_BENIGN; BX_CPU_THIS_PTR assert_RF (); break; case 7: // device not available push_error = 0; exception_type = BX_ET_BENIGN; BX_CPU_THIS_PTR assert_RF (); break; case 8: // double fault push_error = 1; exception_type = BX_ET_DOUBLE_FAULT; break; case 9: // coprocessor segment overrun (286,386 only) push_error = 0; exception_type = BX_ET_CONTRIBUTORY; BX_CPU_THIS_PTR assert_RF (); BX_PANIC(("exception(9): unfinished")); break; case 10: // invalid TSS push_error = 1; exception_type = BX_ET_CONTRIBUTORY; error_code = (error_code & 0xfffe) | BX_CPU_THIS_PTR EXT; BX_CPU_THIS_PTR assert_RF (); break; case 11: // segment not present push_error = 1; exception_type = BX_ET_CONTRIBUTORY; error_code = (error_code & 0xfffe) | BX_CPU_THIS_PTR EXT; BX_CPU_THIS_PTR assert_RF (); break; case 12: // stack fault push_error = 1; exception_type = BX_ET_CONTRIBUTORY; error_code = (error_code & 0xfffe) | BX_CPU_THIS_PTR EXT; BX_CPU_THIS_PTR assert_RF (); break; case 13: // general protection push_error = 1; exception_type = BX_ET_CONTRIBUTORY; error_code = (error_code & 0xfffe) | BX_CPU_THIS_PTR EXT; BX_CPU_THIS_PTR assert_RF (); break; case 14: // page fault if (BX_CPU_THIS_PTR except_chk) // Help with OS/2 { BX_CPU_THIS_PTR except_chk = 0; BX_CPU_THIS_PTR sregs[BX_SEG_REG_CS].selector.value = BX_CPU_THIS_PTR except_cs; BX_CPU_THIS_PTR sregs[BX_SEG_REG_SS].selector.value = BX_CPU_THIS_PTR except_ss; } push_error = 1; exception_type = BX_ET_PAGE_FAULT; // ??? special format error returned BX_CPU_THIS_PTR assert_RF (); break; case 15: // reserved BX_PANIC(("exception(15): reserved")); push_error = 0; // keep compiler happy for now exception_type = 0; // keep compiler happy for now break; case 16: // floating-point error push_error = 0; exception_type = BX_ET_BENIGN; BX_CPU_THIS_PTR assert_RF (); break; #if BX_CPU_LEVEL >= 4 case 17: // alignment check BX_PANIC(("exception(): alignment-check, vector 17 unimplemented")); push_error = 0; // keep compiler happy for now exception_type = 0; // keep compiler happy for now BX_CPU_THIS_PTR assert_RF (); break; #endif #if BX_CPU_LEVEL >= 5 case 18: // machine check BX_PANIC(("exception(): machine-check, vector 18 unimplemented")); push_error = 0; // keep compiler happy for now exception_type = 0; // keep compiler happy for now break; #endif default: BX_PANIC(("exception(%u): bad vector", (unsigned) vector)); push_error = 0; // keep compiler happy for now exception_type = 0; // keep compiler happy for now break; } if (exception_type != BX_ET_PAGE_FAULT) { // Page faults have different format error_code = (error_code & 0xfffe) | BX_CPU_THIS_PTR EXT; } BX_CPU_THIS_PTR EXT = 1; /* if we've already had 1st exception, see if 2nd causes a * Double Fault instead. Otherwise, just record 1st exception */ if (BX_CPU_THIS_PTR errorno >= 2) { if (is_exception_OK[BX_CPU_THIS_PTR curr_exception[0]][exception_type]) BX_CPU_THIS_PTR curr_exception[1] = exception_type; else { BX_CPU_THIS_PTR curr_exception[1] = BX_ET_DOUBLE_FAULT; vector = 8; } } else { BX_CPU_THIS_PTR curr_exception[0] = exception_type; } #if BX_CPU_LEVEL >= 2 if (!real_mode()) { prev_errno = BX_CPU_THIS_PTR errorno; BX_CPU_THIS_PTR interrupt(vector, 0, push_error, error_code); // if (BX_CPU_THIS_PTR errorno > prev_errno) { // BX_INFO(("segment_exception(): errorno changed")); // longjmp(jmp_buf_env, 1); // go back to main decode loop // return; // } // if (push_error) { // /* push error code on stack, after handling interrupt */ // /* pushed as a word or dword depending upon default size ??? */ // if (ss.cache.u.segment.d_b) // push_32((Bit32u) error_code); /* upper bits reserved */ // else // push_16(error_code); // if (BX_CPU_THIS_PTR errorno > prev_errno) { // BX_PANIC(("segment_exception(): errorno changed")); // return; // } // } BX_CPU_THIS_PTR errorno = 0; // error resolved longjmp(BX_CPU_THIS_PTR jmp_buf_env, 1); // go back to main decode loop } else // real mode #endif { // not INT, no error code pushed BX_CPU_THIS_PTR interrupt(vector, 0, 0, 0); BX_CPU_THIS_PTR errorno = 0; // error resolved longjmp(BX_CPU_THIS_PTR jmp_buf_env, 1); // go back to main decode loop } }