// vector: 0..255: vector in IDT
// error_code: if exception generates and error, push this error code
// trap: override exception class to TRAP
void BX_CPU_C::exception(unsigned vector, Bit16u error_code, bx_bool trap)
{
unsigned exception_type = 0, exception_class = BX_EXCEPTION_CLASS_FAULT;
bx_bool push_error = 0;
invalidate_prefetch_q();
BX_INSTR_EXCEPTION(BX_CPU_ID, vector);
#if BX_DEBUGGER
bx_dbg_exception(BX_CPU_ID, vector, error_code);
#endif
BX_DEBUG(("exception(0x%02x): error_code=%04x", vector, error_code));
// 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;
RIP = BX_CPU_THIS_PTR save_eip;
RSP = BX_CPU_THIS_PTR save_esp;
}
if (BX_CPU_THIS_PTR errorno > 0) {
if (errno > 2 || BX_CPU_THIS_PTR curr_exception == BX_ET_DOUBLE_FAULT) {
debug(BX_CPU_THIS_PTR prev_rip); // print debug information to the log
#if BX_DEBUGGER
// trap into debugger (similar as done when PANIC occured)
bx_debug_break();
#endif
if (SIM->get_param_bool(BXPN_RESET_ON_TRIPLE_FAULT)->get()) {
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 !"));
shutdown();
}
longjmp(BX_CPU_THIS_PTR jmp_buf_env, 1); // go back to main decode loop
}
}
// note: fault-class exceptions _except_ #DB set RF in
// eflags image.
switch (vector) {
case BX_DE_EXCEPTION: // DIV by 0
push_error = 0;
exception_class = BX_EXCEPTION_CLASS_FAULT;
exception_type = BX_ET_CONTRIBUTORY;
break;
case BX_DB_EXCEPTION: // debug exceptions
push_error = 0;
// Instruction fetch breakpoint - FAULT
// Data read or write breakpoint - TRAP
// I/O read or write breakpoint - TRAP
// General detect condition - FAULT
// Single-step - TRAP
// Task-switch - TRAP
exception_class = BX_EXCEPTION_CLASS_FAULT;
exception_type = BX_ET_BENIGN;
break;
case 2: // NMI
push_error = 0;
exception_type = BX_ET_BENIGN;
break;
case BX_BP_EXCEPTION: // breakpoint
push_error = 0;
exception_class = BX_EXCEPTION_CLASS_TRAP;
exception_type = BX_ET_BENIGN;
break;
case BX_OF_EXCEPTION: // overflow
push_error = 0;
exception_class = BX_EXCEPTION_CLASS_TRAP;
exception_type = BX_ET_BENIGN;
break;
case BX_BR_EXCEPTION: // bounds check
push_error = 0;
exception_class = BX_EXCEPTION_CLASS_FAULT;
exception_type = BX_ET_BENIGN;
break;
case BX_UD_EXCEPTION: // invalid opcode
push_error = 0;
exception_class = BX_EXCEPTION_CLASS_FAULT;
exception_type = BX_ET_BENIGN;
break;
case BX_NM_EXCEPTION: // device not available
push_error = 0;
exception_class = BX_EXCEPTION_CLASS_FAULT;
exception_type = BX_ET_BENIGN;
break;
case BX_DF_EXCEPTION: // double fault
push_error = 1;
error_code = 0;
exception_class = BX_EXCEPTION_CLASS_ABORT;
exception_type = BX_ET_DOUBLE_FAULT;
break;
case 9: // coprocessor segment overrun (286,386 only)
push_error = 0;
exception_class = BX_EXCEPTION_CLASS_ABORT;
exception_type = BX_ET_BENIGN;
BX_PANIC(("exception(9): unfinished"));
break;
case BX_TS_EXCEPTION: // invalid TSS
push_error = 1;
exception_class = BX_EXCEPTION_CLASS_FAULT;
exception_type = BX_ET_CONTRIBUTORY;
break;
case BX_NP_EXCEPTION: // segment not present
push_error = 1;
exception_class = BX_EXCEPTION_CLASS_FAULT;
exception_type = BX_ET_CONTRIBUTORY;
break;
case BX_SS_EXCEPTION: // stack fault
push_error = 1;
exception_class = BX_EXCEPTION_CLASS_FAULT;
exception_type = BX_ET_CONTRIBUTORY;
break;
case BX_GP_EXCEPTION: // general protection
push_error = 1;
exception_class = BX_EXCEPTION_CLASS_FAULT;
exception_type = BX_ET_CONTRIBUTORY;
break;
case BX_PF_EXCEPTION: // page fault
push_error = 1;
exception_class = BX_EXCEPTION_CLASS_FAULT;
exception_type = BX_ET_PAGE_FAULT;
break;
case 15: // reserved
BX_PANIC(("exception(15): reserved"));
push_error = 0;
exception_type = 0;
break;
case BX_MF_EXCEPTION: // floating-point error
push_error = 0;
exception_class = BX_EXCEPTION_CLASS_FAULT;
exception_type = BX_ET_BENIGN;
break;
#if BX_CPU_LEVEL >= 4
case BX_AC_EXCEPTION: // alignment check
push_error = 1;
exception_class = BX_EXCEPTION_CLASS_FAULT;
exception_type = BX_ET_BENIGN;
break;
#endif
#if BX_CPU_LEVEL >= 5
case BX_MC_EXCEPTION: // machine check
BX_PANIC(("exception(): machine-check, vector 18 not implemented"));
push_error = 0;
exception_class = BX_EXCEPTION_CLASS_ABORT;
exception_type = BX_ET_BENIGN;
break;
#if BX_SUPPORT_SSE
case BX_XM_EXCEPTION: // SIMD Floating-Point exception
push_error = 0;
exception_class = BX_EXCEPTION_CLASS_FAULT;
exception_type = BX_ET_BENIGN;
break;
#endif
#endif
default:
BX_PANIC(("exception(%u): bad vector", (unsigned) vector));
exception_type = BX_ET_BENIGN;
push_error = 0; // keep compiler happy for now
break;
}
if (trap) {
exception_class = BX_EXCEPTION_CLASS_TRAP;
}
else {
if (exception_class == BX_EXCEPTION_CLASS_FAULT)
{
// restore RIP/RSP to value before error occurred
RIP = BX_CPU_THIS_PTR prev_rip;
if (BX_CPU_THIS_PTR speculative_rsp)
RSP = BX_CPU_THIS_PTR prev_rsp;
if (vector != BX_DB_EXCEPTION) BX_CPU_THIS_PTR assert_RF();
}
}
// clear GD flag in the DR7 prior entering debug exception handler
if (vector == BX_DB_EXCEPTION)
BX_CPU_THIS_PTR dr7 &= ~0x00002000;
if (exception_type != BX_ET_PAGE_FAULT) {
// Page faults have different format
error_code = (error_code & 0xfffe) | BX_CPU_THIS_PTR EXT;
}
else {
// FIXME: special format error returned for page faults ?
}
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 > 0) {
if (is_exception_OK[BX_CPU_THIS_PTR curr_exception][exception_type]) {
BX_CPU_THIS_PTR curr_exception = exception_type;
}
else {
exception(BX_DF_EXCEPTION, 0, 0);
}
}
else {
BX_CPU_THIS_PTR curr_exception = exception_type;
}
BX_CPU_THIS_PTR errorno++;
if (real_mode()) {
// 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
}
else {
BX_CPU_THIS_PTR interrupt(vector, 0, push_error, error_code);
BX_CPU_THIS_PTR errorno = 0; // error resolved
longjmp(BX_CPU_THIS_PTR jmp_buf_env, 1); // go back to main decode loop
}
}
// vector: 0..255: vector in IDT
// error_code: if exception generates and error, push this error code
// trap: override exception class to TRAP
void BX_CPU_C::exception(unsigned vector, Bit16u error_code)
{
BX_INSTR_EXCEPTION(BX_CPU_ID, vector, error_code);
#if BX_DEBUGGER
bx_dbg_exception(BX_CPU_ID, vector, error_code);
#endif
BX_DEBUG(("exception(0x%02x): error_code=%04x", vector, error_code));
unsigned exception_type = 0;
unsigned exception_class = BX_EXCEPTION_CLASS_FAULT;
bx_bool push_error = 0;
if (vector < BX_CPU_HANDLED_EXCEPTIONS) {
push_error = exceptions_info[vector].push_error;
exception_class = exceptions_info[vector].exception_class;
exception_type = exceptions_info[vector].exception_type;
}
else {
BX_PANIC(("exception(%u): bad vector", vector));
}
if (vector != BX_PF_EXCEPTION && vector != BX_DF_EXCEPTION) {
// Page faults have different format
error_code = (error_code & 0xfffe) | BX_CPU_THIS_PTR EXT;
}
#if BX_SUPPORT_VMX
VMexit_Event(0, BX_HARDWARE_EXCEPTION, vector, error_code, push_error);
#endif
if (BX_CPU_THIS_PTR errorno > 0) {
if (BX_CPU_THIS_PTR errorno > 2 || BX_CPU_THIS_PTR curr_exception == BX_ET_DOUBLE_FAULT) {
// restore RIP/RSP to value before error occurred
RIP = BX_CPU_THIS_PTR prev_rip;
if (BX_CPU_THIS_PTR speculative_rsp)
RSP = BX_CPU_THIS_PTR prev_rsp;
debug(BX_CPU_THIS_PTR prev_rip); // print debug information to the log
#if BX_SUPPORT_VMX
VMexit_TripleFault();
#endif
#if BX_DEBUGGER
// trap into debugger (similar as done when PANIC occured)
bx_debug_break();
#endif
if (SIM->get_param_bool(BXPN_RESET_ON_TRIPLE_FAULT)->get()) {
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_HARDWARE);
}
else {
BX_PANIC(("exception(): 3rd (%d) exception with no resolution", vector));
BX_ERROR(("WARNING: Any simulation after this point is completely bogus !"));
shutdown();
}
longjmp(BX_CPU_THIS_PTR jmp_buf_env, 1); // go back to main decode loop
}
}
// note: fault-class exceptions _except_ #DB set RF in
// eflags image.
if (exception_class == BX_EXCEPTION_CLASS_FAULT)
{
// restore RIP/RSP to value before error occurred
RIP = BX_CPU_THIS_PTR prev_rip;
if (BX_CPU_THIS_PTR speculative_rsp)
RSP = BX_CPU_THIS_PTR prev_rsp;
if (vector != BX_DB_EXCEPTION) BX_CPU_THIS_PTR assert_RF();
}
if (vector == BX_DB_EXCEPTION) {
// Commit debug events to DR6
#if BX_CPU_LEVEL <= 4
// On 386/486 bit12 is settable
BX_CPU_THIS_PTR dr6.val32 = (BX_CPU_THIS_PTR dr6.val32 & 0xffff0ff0) |
(BX_CPU_THIS_PTR debug_trap & 0x0000f00f);
#else
// On Pentium+, bit12 is always zero
BX_CPU_THIS_PTR dr6.val32 = (BX_CPU_THIS_PTR dr6.val32 & 0xffff0ff0) |
(BX_CPU_THIS_PTR debug_trap & 0x0000e00f);
#endif
// clear GD flag in the DR7 prior entering debug exception handler
BX_CPU_THIS_PTR dr7.set_GD(0);
}
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 > 0 && exception_type != BX_ET_DOUBLE_FAULT) {
if (! is_exception_OK[BX_CPU_THIS_PTR curr_exception][exception_type]) {
exception(BX_DF_EXCEPTION, 0);
}
}
BX_CPU_THIS_PTR curr_exception = exception_type;
BX_CPU_THIS_PTR errorno++;
if (real_mode()) {
push_error = 0; // not INT, no error code pushed
error_code = 0;
}
interrupt(vector, BX_HARDWARE_EXCEPTION, push_error, error_code);
BX_CPU_THIS_PTR errorno = 0; // error resolved
longjmp(BX_CPU_THIS_PTR jmp_buf_env, 1); // go back to main decode loop
}
void logfunctions::ask(int level, const char *prefix, const char *fmt, va_list ap)
{
// Guard against reentry on ask() function. The danger is that some
// function that's called within ask() could trigger another
// BX_PANIC that could call ask() again, leading to infinite
// recursion and infinite asks.
static char in_ask_already = 0;
char buf1[1024];
if (in_ask_already) {
fprintf(stderr, "logfunctions::ask() should not reenter!!\n");
return;
}
in_ask_already = 1;
vsnprintf(buf1, sizeof(buf1), fmt, ap);
// FIXME: facility set to 0 because it's unknown.
// update vga screen. This is useful because sometimes useful messages
// are printed on the screen just before a panic. It's also potentially
// dangerous if this function calls ask again... That's why I added
// the reentry check above.
if (SIM->get_init_done()) DEV_vga_refresh();
#if !BX_EXTERNAL_DEBUGGER
// ensure the text screen is showing
SIM->set_display_mode(DISP_MODE_CONFIG);
int val = SIM->log_msg(prefix, level, buf1);
switch(val)
{
case BX_LOG_ASK_CHOICE_CONTINUE:
break;
case BX_LOG_ASK_CHOICE_CONTINUE_ALWAYS:
// user said continue, and don't "ask" for this facility again.
setonoff(level, ACT_REPORT);
break;
case BX_LOG_ASK_CHOICE_DIE:
case BX_LOG_NOTIFY_FAILED:
bx_user_quit = (val==BX_LOG_ASK_CHOICE_DIE)?1:0;
in_ask_already = 0; // because fatal will longjmp out
fatal(prefix, buf1, ap, 1);
// should never get here
BX_PANIC(("in ask(), fatal() should never return!"));
break;
case BX_LOG_ASK_CHOICE_DUMP_CORE:
fprintf(stderr, "User chose to dump core...\n");
#if BX_HAVE_ABORT
abort();
#else
// do something highly illegal that should kill the process.
// Hey, this is fun!
{
char *crashptr = (char *)0; char c = *crashptr;
}
fprintf(stderr, "Sorry, I couldn't find your abort() function. Exiting.");
exit(0);
#endif
#if BX_DEBUGGER
case BX_LOG_ASK_CHOICE_ENTER_DEBUG:
// user chose debugger. To "drop into the debugger" we just set the
// interrupt_requested bit and continue execution. Before the next
// instruction, it should notice the user interrupt and return to
// the debugger.
bx_debug_break();
break;
#elif BX_GDBSTUB
case BX_LOG_ASK_CHOICE_ENTER_DEBUG:
bx_gdbstub_break();
break;
#endif
default:
// this happens if panics happen before the callback is initialized
// in gui/control.cc.
fprintf(stderr, "WARNING: log_msg returned unexpected value %d\n", val);
}
#else
// external debugger ask code goes here
#endif
// return to simulation mode
SIM->set_display_mode(DISP_MODE_SIM);
in_ask_already = 0;
}
