static void mouse_callback(struct sigcontext *scp,
const struct RealModeCallStructure *rmreg,
int is_32, void *arg)
{
void *sp = SEL_ADR_CLNT(_ss, _esp, is_32);
struct pmaddr_s *mouseCallBack = arg;
if (!ValidAndUsedSelector(mouseCallBack->selector)) {
D_printf("MSDOS: ERROR: mouse callback to unused segment\n");
return;
}
D_printf("MSDOS: starting mouse callback\n");
if (is_32) {
unsigned int *ssp = sp;
*--ssp = _cs;
*--ssp = _eip;
_esp -= 8;
} else {
unsigned short *ssp = sp;
*--ssp = _cs;
*--ssp = _LWORD(eip);
_LWORD(esp) -= 4;
}
rm_to_pm_regs(scp, rmreg, ~(1 << ebp_INDEX));
_ds = ConvertSegmentToDescriptor(RMREG(ds));
_cs = mouseCallBack->selector;
_eip = mouseCallBack->offset;
}
int msdos_fault(struct sigcontext *scp)
{
struct sigcontext new_sct;
int reg;
unsigned int segment;
unsigned short desc;
D_printf("MSDOS: msdos_fault, err=%#lx\n", _err);
if ((_err & 0xffff) == 0) /* not a selector error */
return msdos_ldt_fault(scp);
/* now it is a invalid selector error, try to fix it if it is */
/* caused by an instruction such as mov Sreg,r/m16 */
#define ALL_GDTS 0
#if !ALL_GDTS
segment = (_err & 0xfff8);
/* only allow using some special GTDs */
switch (segment) {
case 0x0040:
case 0xa000:
case 0xb000:
case 0xb800:
case 0xc000:
case 0xe000:
case 0xf000:
case 0xbf8:
case 0xf800:
case 0xff00:
case 0x38: // ShellShock installer
break;
default:
return 0;
}
copy_context(&new_sct, scp, 0);
reg = decode_segreg(&new_sct);
if (reg == -1)
return 0;
#else
copy_context(&new_sct, scp, 0);
reg = decode_modify_segreg_insn(&new_sct, 1, &segment);
if (reg == -1)
return 0;
if (ValidAndUsedSelector(segment)) {
/*
* The selector itself is OK, but the descriptor (type) is not.
* We cannot fix this! So just give up immediately and dont
* screw up the context.
*/
D_printf("MSDOS: msdos_fault: Illegal use of selector %#x\n",
segment);
return 0;
}
#endif
D_printf("MSDOS: try mov to a invalid selector 0x%04x\n", segment);
switch (segment) {
case 0x38:
/* dos4gw sets VCPI descriptors 0x28, 0x30, 0x38 */
/* The 0x38 is the "flat data" segment (0,4G) */
desc = ConvertSegmentToDescriptor_lim(0, 0xffffffff);
break;
default:
/* any other special cases? */
desc = ConvertSegmentToDescriptor(segment);
}
if (!desc)
return 0;
/* OKay, all the sanity checks passed. Now we go and fix the selector */
copy_context(scp, &new_sct, 0);
switch (reg) {
case es_INDEX:
_es = desc;
break;
case cs_INDEX:
_cs = desc;
break;
case ss_INDEX:
_ss = desc;
break;
case ds_INDEX:
_ds = desc;
break;
case fs_INDEX:
_fs = desc;
break;
case gs_INDEX:
_gs = desc;
break;
}
/* let's hope we fixed the thing, and return */
return 1;
}
