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Added 286-Callgates and return to higher privilege

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Imported-from: https://svn.code.sf.net/p/dosbox/code-0/dosbox/trunk@1281
This commit is contained in:
Ulf Wohlers 2003-09-30 13:48:20 +00:00
parent 4114c37e3e
commit a031928dcb
1 changed files with 78 additions and 2 deletions
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80
src/cpu/cpu.cpp
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@ -16,7 +16,7 @@
* Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA.
*/
/* $Id: cpu.cpp,v 1.33 2003-09-29 21:05:59 qbix79 Exp $ */
/* $Id: cpu.cpp,v 1.34 2003-09-30 13:48:20 finsterr Exp $ */
#include <assert.h>
#include "dosbox.h"
@ -101,6 +101,7 @@ bool CPU_CheckCodeType(CODE_TYPE type) {
switch (cpu.code.type) {
case CODE_REAL:
realcore_start(false);
cpu.code.big = false;
break;
case CODE_PMODE16:
pmodecore_start(false);
@ -406,6 +407,71 @@ call_code:
Segs.val[cs]=(selector & 0xfffc) | cpu.cpl;
reg_eip=offset;
return CPU_CheckCodeType(cpu.code.big ? CODE_PMODE32 : CODE_PMODE16);
case DESC_286_CALL_GATE: {
if (call.DPL()<cpu.cpl) E_Exit("286 Call Gate: Gate DPL<CPL");
if (call.DPL()<rpl) E_Exit("286 Call Gate: Gate DPL<RPL");
Descriptor code;
if (!cpu.gdt.GetDescriptor(call.GetSelector(),code)) E_Exit("286 Call Gate: Invalid code segment.");
Bitu seldpl = code.DPL();
if (seldpl<cpu.cpl) {
// higher privilidge level
// Get new SS selector for new privilege level from TSS
// We dont have a TSS now, so we ´simply use our existing stack...
// 1. Load new SS:eSP value from TSS
// 2. Load new CS:EIP value from gate
Bitu newcs = call.GetSelector();
Bitu neweip = call.GetOffset();
Bitu newcpl = seldpl;
Bitu oldcs = SegValue(cs);
Bitu oldip = reg_ip;
// 3. Load CS descriptor (Set RPL of CS to CPL)
Segs.phys[cs] = code.GetBase();
cpu.code.big = code.Big()>0;
reg_eip = neweip;
// Set CPL to stack segment DPL
// Set RPL of CS to CPL
cpu.cpl = newcpl;
Segs.val[cs] = (newcs & 0xfffc) | newcpl;
// 4. Load SS descriptor
// 5. Push long pointer of old stack onto new stack
Bitu oldsp = reg_sp;
CPU_Push16(SegValue(ss));
CPU_Push16(oldsp);
// 6. Get word count from call gate, mask to 5 bits
Bitu wordCount = call.saved.gate.paramcount;
if (wordCount>0) LOG(LOG_CPU,LOG_NORMAL)("CPU: Callgate 286 wordcount : %d)",wordCount);
// 7. Copy parameters from old stack onto new stack
while (wordCount>0) {
CPU_Push16(mem_readw(SegPhys(ss)+oldsp));
oldsp += 2; wordCount--;
}
// Push return address onto new stack
CPU_Push16(oldcs);
CPU_Push16(oldip);
// LOG(LOG_MISC,LOG_ERROR)("CPU: Callgate (Higher) %04X:%04X",newcs,neweip);
return CPU_CheckCodeType(cpu.code.big ? CODE_PMODE32 : CODE_PMODE16);
} else {
// same privilidge level
Bitu oldcs = SegValue(cs);
Bitu oldip = reg_ip;
Bitu newcs = call.GetSelector() | 3;
Bitu neweip = call.GetOffset();
// 3. Load CS descriptor (Set RPL of CS to CPL)
Descriptor code2;
if (!cpu.gdt.GetDescriptor(newcs,code2)) E_Exit("286 Call Gate: Invalid code segment.");
Segs.phys[cs] = code.GetBase();
cpu.code.big = code.Big()>0;
// Set RPL of CS to CPL
cpu.cpl = seldpl;
Segs.val[cs] = (newcs & 0xfffc) | seldpl;
reg_eip = neweip;
// Push return address onto new stack
CPU_Push16(oldcs);
CPU_Push16(oldip);
// LOG(LOG_MISC,LOG_ERROR)("CPU: Callgate (Same) %04X:%04X",newcs,neweip);
return CPU_CheckCodeType(cpu.code.big ? CODE_PMODE32 : CODE_PMODE16);
}; break;
};
default:
E_Exit("CALL:Descriptor type %x unsupported",call.Type());
@ -472,7 +538,17 @@ RET_same_level:
return CPU_CheckCodeType(cpu.code.big ? CODE_PMODE32 : CODE_PMODE16);
} else {
/* Return to higher level */
E_Exit("REturn to higher priviledge");
Bitu newsp = CPU_Pop16();
Bitu newss = CPU_Pop16();
cpu.cpl = rpl;
CPU_SetSegGeneral(ss,newss);
reg_esp = newsp;
Segs.phys[cs]=desc.GetBase();
cpu.code.big=desc.Big()>0;
Segs.val[cs]=selector;
reg_eip=offset;
// LOG(LOG_MISC,LOG_ERROR)("RET - Higher level to %X:%X RPL %X DPL %X",selector,offset,rpl,desc.DPL());
return CPU_CheckCodeType(cpu.code.big ? CODE_PMODE32 : CODE_PMODE16);
}
LOG(LOG_CPU,LOG_NORMAL)("Prot ret %X:%X",selector,offset);
return CPU_CheckCodeType(cpu.code.big ? CODE_PMODE32 : CODE_PMODE16);