Source code of Windows XP (NT5)
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/*++
Copyright (c) 1991 Microsoft Corporation
Module Name:
main.c
Abstract:
Main for the SU (startup) module for the OS loader. The SU module
must take the x86 from a real-mode 16bit state to a FLAT model,
32bit protect/paging enabled state.
Author:
Thomas Parslow (tomp) Created 20-Dec-90
Revision History:
--*/
#define NTAPI
#include "su.h"
#include "eisa.h"
#define _SYS_GUID_OPERATORS_
#include <guiddef.h>
#include "ntimage.h"
#include "strings.h"
extern VOID RealMode(VOID);
extern USHORT IDTregisterZero;
extern IMAGE_DOS_HEADER edata;
extern USHORT end;
extern VOID MoveMemory(ULONG,ULONG,ULONG);
extern USHORT SuStackBegin;
extern UCHAR Beginx86Relocation;
extern UCHAR Endx86Relocation;
extern USHORT BackEnd;
extern ULONG FileStart;
extern BOOLEAN IsNpxPresent(VOID);
extern USHORT HwGetProcessorType(VOID);
extern USHORT HwGetCpuStepping(USHORT);
extern ULONG MachineType;
extern ULONG OsLoaderStart;
extern ULONG OsLoaderEnd;
extern ULONG ResourceDirectory;
extern ULONG ResourceOffset;
extern ULONG OsLoaderBase;
extern ULONG OsLoaderExports;
extern
TurnMotorOff(
VOID
);
extern
EnableA20(
VOID
);
extern
BOOLEAN
ConstructMemoryDescriptors(
VOID
);
extern
USHORT
IsaConstructMemoryDescriptors(
VOID
);
VOID
Relocatex86Structures(
VOID
);
ULONG
RelocateLoaderSections(
OUT PULONG Start,
OUT PULONG End
);
extern
FSCONTEXT_RECORD
FsContext;
#define DISK_TABLE_VECTOR (0x1e*4)
FPULONG DiskTableVector = (FPULONG)(DISK_TABLE_VECTOR);
VOID
SuMain(
IN UCHAR BtBootDrive
)
/*++
Routine Description:
Main entrypoint of the SU module. Control is passed from the boot
sector to startup.asm which does some run-time fixups on the stack
and data segments and then passes control here.
Arguments:
BtBootDrive - Drive that we booted from (int13 unit number)
Returns:
Does not return. Passes control to the OS loader
--*/
{
ULONG LoaderEntryPoint;
ULONG EisaNumPages;
USHORT IsaNumPages;
MEMORY_LIST_ENTRY _far *CurrentEntry;
PIMAGE_OPTIONAL_HEADER OptionalHeader;
ULONG BlockEnd;
ULONG ImageSize;
ULONG ImageBase;
//
// Save fs context info
//
FsContext.BootDrive = BtBootDrive;
//
// Initialize the video subsystem first so that
// errors end exceptions can be displayed.
//
InitializeVideoSubSystem();
//
// In case we booted from a floppy, turn the drive motor off.
//
TurnMotorOff();
//
// Set up machine type based on its Bus type.
//
if (BtIsEisaSystem()) {
MachineType = MACHINE_TYPE_EISA;
} else {
MachineType = MACHINE_TYPE_ISA;
}
if (!ConstructMemoryDescriptors()) {
//
// If INT 15 E802h fails...
//
if (MachineType == MACHINE_TYPE_EISA) {
//
// HACKHACK John Vert (jvert)
// This is completely bogus. Since there are a number of EISA
// machines which do not let you correctly configure the EISA
// NVRAM, and even MORE machines which are improperly configured,
// we first check to see how much memory the ISA routines say
// exists. Then we check what the EISA routines tell us, and
// compare the two. If the EISA number is much lower (where "much"
// is a completely random fudge factor) than the ISA number, we
// assume the machine is improperly configured and we throw away
// the EISA numbers and use the ISA ones. If not, we assume that
// the machine is actually configured properly and we trust the
// EISA numbers..
//
IsaNumPages = IsaConstructMemoryDescriptors();
EisaNumPages = EisaConstructMemoryDescriptors();
if (EisaNumPages + 0x80 < IsaNumPages) {
IsaConstructMemoryDescriptors();
}
} else {
IsaConstructMemoryDescriptors();
}
}
//
// Search for memory descriptor describing low memory
//
CurrentEntry = MemoryDescriptorList;
while ((CurrentEntry->BlockBase != 0) &&
(CurrentEntry->BlockSize != 0)) {
CurrentEntry++;
}
if ((CurrentEntry->BlockBase == 0) &&
(CurrentEntry->BlockSize < (ULONG)512 * (ULONG)1024)) {
BlPrint(SU_NO_LOW_MEMORY,CurrentEntry->BlockSize/1024);
while (1) {
}
}
//
// Ensure there is a memory descriptor to contain osloader image
//
OptionalHeader = &((PIMAGE_NT_HEADERS) ((PUCHAR) &edata + edata.e_lfanew))->OptionalHeader;
ImageBase = OptionalHeader->ImageBase;
ImageSize = OptionalHeader->SizeOfImage;
OsLoaderBase = ImageBase;
OsLoaderExports = ImageBase + OptionalHeader->DataDirectory[IMAGE_DIRECTORY_ENTRY_EXPORT].VirtualAddress;
CurrentEntry = MemoryDescriptorList;
while (ImageSize > 0) {
while (CurrentEntry->BlockSize != 0) {
BlockEnd = CurrentEntry->BlockBase + CurrentEntry->BlockSize;
if ((CurrentEntry->BlockBase <= ImageBase) &&
(BlockEnd > ImageBase)) {
//
// this descriptor at least partially contains a chunk
// of the osloader.
//
if (BlockEnd-ImageBase > ImageSize) {
ImageSize = 0;
} else {
ImageSize -= (BlockEnd-ImageBase);
ImageBase = BlockEnd;
}
//
// look for remaining part (if any) of osloader
//
CurrentEntry = MemoryDescriptorList;
break;
}
CurrentEntry++;
}
if (CurrentEntry->BlockSize == 0) {
break;
}
}
if (ImageSize > 0) {
//
// We could not relocate the osloader to high memory. Error out
// and display the memory map.
//
BlPrint(SU_NO_EXTENDED_MEMORY);
CurrentEntry = MemoryDescriptorList;
while (CurrentEntry->BlockSize != 0) {
BlPrint(" %lx - %lx\n",
CurrentEntry->BlockBase,
CurrentEntry->BlockBase + CurrentEntry->BlockSize);
CurrentEntry++;
}
while (1) {
}
}
//
// Enable the A20 line for protect mode
//
EnableA20();
//
// Relocate x86 structures. This includes the GDT, IDT,
// page directory, and first level page table.
//
Relocatex86Structures();
//
// Enable protect and paging modes for the first time
//
EnableProtectPaging(ENABLING);
//
// Go relocate loader sections and build page table entries
//
LoaderEntryPoint = RelocateLoaderSections(&OsLoaderStart, &OsLoaderEnd);
//
// Search for memory descriptor containing the osloader and
// change it.
//
//
// Transfer control to the OS loader
//
TransferToLoader(LoaderEntryPoint);
}
ULONG
RelocateLoaderSections(
OUT PULONG Start,
OUT PULONG End
)
/*++
Routine Description:
The SU module is prepended to the OS loader file. The OS loader file
is a coff++ file. This routine computes the beginning of the OS loader
file, then relocates the OS loader's sections as if it were just
loading the file from disk file.
Arguments:
Start - Returns the address of the start of the image
End - Returns the address of the end of the image
Returns:
Entry point of loader
--*/
{
USHORT Section;
ULONG Source,Destination;
ULONG VirtualSize;
ULONG SizeOfRawData;
PIMAGE_FILE_HEADER FileHeader;
PIMAGE_OPTIONAL_HEADER OptionalHeader;
PIMAGE_SECTION_HEADER SectionHeader;
//
// Make a pointer to the beginning of the loader's coff header
//
FileHeader = &((PIMAGE_NT_HEADERS) ((PUCHAR) &edata + edata.e_lfanew))->FileHeader;
//
// Validate the appended loader image by checking signatures.
// 1st - is it an executable image?
// 2nd - is the target environment the 386?
//
if ((FileHeader->Characteristics & IMAGE_FILE_EXECUTABLE_IMAGE) == 0) {
puts(SU_NTLDR_CORRUPT);
WAITFOREVER;
}
if (FileHeader->Machine != IMAGE_FILE_MACHINE_I386) {
puts(SU_NTLDR_CORRUPT);
WAITFOREVER;
}
//
// Make a pointer to the optional header in the header-buffer
//
OptionalHeader = (PIMAGE_OPTIONAL_HEADER)((PUCHAR)FileHeader +
sizeof(IMAGE_FILE_HEADER));
//
// Make a pointer to the first section in the header buffer
//
SectionHeader = (PIMAGE_SECTION_HEADER)((PUCHAR)OptionalHeader +
FileHeader->SizeOfOptionalHeader);
*Start = OptionalHeader->ImageBase+SectionHeader->VirtualAddress;
*End = *Start + SectionHeader->SizeOfRawData;
//
// Display some debug stuff for now
//
DBG1(
BlPrint("Machine = %x\n",FileHeader->Machine);
BlPrint("NumberOfSections = %x\n",FileHeader->NumberOfSections);
BlPrint("TimeDateStamp %lx\n",FileHeader->TimeDateStamp);
BlPrint("PointerToSymbolTable = %lx\n",FileHeader->PointerToSymbolTable);
BlPrint("NumberOfSymbols %lx\n",FileHeader->NumberOfSymbols);
BlPrint("SizeOfOptionalHeader = %x\n",FileHeader->SizeOfOptionalHeader);
BlPrint("Characteristics = %x\n",FileHeader->Characteristics);
)
//
// Loop and relocate each section with a non-zero RawData size
//
for (Section=FileHeader->NumberOfSections ; Section-- ; SectionHeader++) {
//
// Compute source, destination, and count arguments
//
Source = FileStart + SectionHeader->PointerToRawData;
Destination = OptionalHeader->ImageBase + SectionHeader->VirtualAddress;
VirtualSize = SectionHeader->Misc.VirtualSize;
SizeOfRawData = SectionHeader->SizeOfRawData;
if (VirtualSize == 0) {
VirtualSize = SizeOfRawData;
}
if (SectionHeader->PointerToRawData == 0) {
//
// SizeOfRawData can be non-zero even if PointerToRawData is zero
//
SizeOfRawData = 0;
} else if (SizeOfRawData > VirtualSize) {
//
// Don't load more from image than is expected in memory
//
SizeOfRawData = VirtualSize;
}
if (Destination < *Start) {
*Start = Destination;
}
if (Destination+VirtualSize > *End) {
*End = Destination+VirtualSize;
}
DBG1(BlPrint("src=%lx dest=%lx raw=%lx\n",Source,Destination,SizeOfRawData);)
if (SizeOfRawData != 0) {
//
// This section is either a code (.TEXT) section or an
// initialized data (.DATA) section.
// Relocate the section to memory at the virtual/physical
// addresses specified in the section header.
//
MoveMemory(Source,Destination,SizeOfRawData);
}
if (SizeOfRawData < VirtualSize) {
//
// Zero the portion not loaded from the image
//
DBG1( BlPrint("Zeroing destination %lx\n",Destination+SizeOfRawData); )
ZeroMemory(Destination+SizeOfRawData,VirtualSize - SizeOfRawData);
}
//
// Check if this is the resource section. If so, we need
// to pass its location to the osloader.
//
if ((SectionHeader->Name[0] == '.') &&
(SectionHeader->Name[1] == 'r') &&
(SectionHeader->Name[2] == 's') &&
(SectionHeader->Name[3] == 'r') &&
(SectionHeader->Name[4] == 'c')) {
ResourceDirectory = Destination;
ResourceOffset = SectionHeader->VirtualAddress;
}
}
DBG1( BlPrint("RelocateLoaderSections done - EntryPoint == %lx\n",
OptionalHeader->AddressOfEntryPoint + OptionalHeader->ImageBase);)
return(OptionalHeader->AddressOfEntryPoint + OptionalHeader->ImageBase);
}
VOID
Relocatex86Structures(
VOID
)
/*++
Routine Description:
The gdt and idt are statically defined and imbedded in the SU modules
data segment. This routine moves then out of the data segment and into
a page mapped at a defined location.
Arguments:
None
Returns:
Nothing
--*/
{
FPUCHAR Fpsrc, Fpdst;
USHORT Count;
//
// Make pointers to the data and compute the size
// of the block to use.
//
Fpsrc = (FPUCHAR)&Beginx86Relocation;
MAKE_FP(Fpdst,SYSTEM_STRUCTS_BASE_PA);
Count = (&Endx86Relocation - &Beginx86Relocation);
//
// Move the data to its new location
//
while (Count--) {
*Fpdst++ = *Fpsrc++;
}
}
VOID
DisplayArgs(
USHORT es,
USHORT bx,
USHORT cx,
USHORT dx,
USHORT ax
)
/*++
Routine Description:
Just a debugging routine to dump some registers.
Arguments:
The x86 registers es, bx, cx, dx, and ax are pushed on the stack
before this routine is called.
Returns:
Nothing
Environment:
Real Mode ONLY
--*/
{
BlPrint("ax:%x dx:%x cx:%x bx:%x es:%x\n",
(USHORT) ax,
(USHORT) dx,
(USHORT) cx,
(USHORT) bx,
(USHORT) es);
return;
}
// END OF FILE //