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94 lines
2.4 KiB
94 lines
2.4 KiB
10 months ago
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// Copyright (C) 2003, Matt Conover (mconover@gmail.com)
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#include "cpu.h"
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#include <assert.h>
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// NOTE: this assumes default scenarios (i.e., we assume CS/DS/ES/SS and flat
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// and all have a base of 0 and limit of 0xffffffff, we don't try to verify
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// that in the GDT)
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//
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// TODO: use inline assembly to get selector for segment
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// Segment = x86 segment register (SEG_ES = 0, SEG_CS = 1, ...)
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BYTE *GetAbsoluteAddressFromSegment(BYTE Segment, DWORD Offset)
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{
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switch (Segment)
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{
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// Windows uses a flat address space (except FS for x86 and GS for x64)
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case 0: // SEG_ES
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case 1: // SEG_CS
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case 2: // SEG_SS
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case 3: // SEG_DS
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return (BYTE *)(DWORD_PTR)Offset;
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case 4: // SEG_FS
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case 5: // SEG_GS
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return (BYTE *)(DWORD_PTR)Offset;
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// Note: we're really supposed to do this, but get_teb is not implemented
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// in this bastardized version of the disassembler.
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// return (BYTE *)get_teb() + Offset;
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default:
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assert(0);
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return (BYTE *)(DWORD_PTR)Offset;
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}
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}
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// This is an GDT/LDT selector (pGDT+Selector)
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BYTE *GetAbsoluteAddressFromSelector(WORD Selector, DWORD Offset)
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{
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DESCRIPTOR_ENTRY Entry;
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GATE_ENTRY *Gate;
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ULONG_PTR Base;
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assert(Selector < 0x10000);
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if (!GetThreadSelectorEntry(GetCurrentThread(), Selector, (LDT_ENTRY *)&Entry)) return NULL;
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if (!Entry.Present) return NULL;
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if (Entry.System)
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{
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Base = 0;
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#ifdef _WIN64
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Base |= (ULONG_PTR)Entry.HighOffset64 << 32;
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#endif
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Base |= Entry.BaseHi << 24;
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Base |= Entry.BaseMid << 16;
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Base |= Entry.BaseLow;
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}
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else
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{
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switch (Entry.Type)
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{
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case 1: // 16-bit TSS (available)
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case 2: // LDT
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case 3: // 16-bit TSS (busy)
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case 9: // 32-bit TSS (available)
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case 11: // 32-bit TSS (busy)
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Base = 0;
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#ifdef _WIN64
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Base |= (ULONG_PTR)Entry.HighOffset64 << 32;
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#endif
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Base |= Entry.BaseHi << 24;
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Base |= Entry.BaseMid << 16;
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Base |= Entry.BaseLow;
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break;
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case 4: // 16-bit call gate
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case 5: // task gate
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case 6: // 16-bit interrupt gate
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case 7: // 16-bit task gate
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case 12: // 32-bit call gate
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case 14: // 32-bit interrupt gate
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case 15: // 32-bit trap gate
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Gate = (GATE_ENTRY *)&Entry;
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#ifdef _WIN64
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Base = ((ULONG_PTR)Gate->HighOffset64 << 32) | (Gate->HighOffset << 16) | Gate->LowOffset;
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#else
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Base = (Gate->HighOffset << 16) | Gate->LowOffset;
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#endif
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assert(!Offset); Offset = 0;
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break;
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default:
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assert(0);
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return NULL;
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}
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}
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return (BYTE *)Base + Offset;
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}
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