Leaked source code of windows server 2003
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184 lines
4.6 KiB

/*++
Copyright (c) 1990 Microsoft Corporation
Module Name:
context.c
Abstract:
This module contains the context management routines for
Win32
Author:
Mark Lucovsky (markl) 28-Sep-1990
Revision History:
--*/
#include "basedll.h"
#ifdef _X86_
extern PVOID BasepLockPrefixTable;
extern PVOID __safe_se_handler_table[]; /* base of safe handler entry table */
extern BYTE __safe_se_handler_count; /* absolute symbol whose address is
the count of table entries */
//
// Specify address of kernel32 lock prefixes
//
IMAGE_LOAD_CONFIG_DIRECTORY _load_config_used = {
sizeof(_load_config_used), // Reserved
0, // Reserved
0, // Reserved
0, // Reserved
0, // GlobalFlagsClear
0, // GlobalFlagsSet
0, // CriticalSectionTimeout (milliseconds)
0, // DeCommitFreeBlockThreshold
0, // DeCommitTotalFreeThreshold
(ULONG) &BasepLockPrefixTable, // LockPrefixTable
0, 0, 0, 0, 0, 0, 0, // Reserved
0, // & security_cookie
(ULONG)__safe_se_handler_table,
(ULONG)&__safe_se_handler_count
};
#endif
VOID
BaseInitializeContext(
OUT PCONTEXT Context,
IN PVOID Parameter OPTIONAL,
IN PVOID InitialPc OPTIONAL,
IN PVOID InitialSp OPTIONAL,
IN BASE_CONTEXT_TYPE ContextType
)
/*++
Routine Description:
This function initializes a context structure so that it can
be used in a subsequent call to NtCreateThread.
Arguments:
Context - Supplies a context buffer to be initialized by this routine.
Parameter - Supplies the thread's parameter.
InitialPc - Supplies an initial program counter value.
InitialSp - Supplies an initial stack pointer value.
NewThread - Supplies a flag that specifies that this is a new
thread, or a new process.
Return Value:
Raises STATUS_BAD_INITIAL_STACK if the value of InitialSp is not properly
aligned.
Raises STATUS_BAD_INITIAL_PC if the value of InitialPc is not properly
aligned.
--*/
{
ULONG ContextFlags;
Context->Eax = (ULONG)InitialPc;
Context->Ebx = (ULONG)Parameter;
Context->SegGs = 0;
Context->SegFs = KGDT_R3_TEB;
Context->SegEs = KGDT_R3_DATA;
Context->SegDs = KGDT_R3_DATA;
Context->SegSs = KGDT_R3_DATA;
Context->SegCs = KGDT_R3_CODE;
//
// Save context flags and set context flags to full.
//
ContextFlags = Context->ContextFlags;
Context->ContextFlags = CONTEXT_FULL;
//
// Start the thread at IOPL=3.
//
Context->EFlags = 0x3000;
//
// Always start the thread at the thread start thunk.
//
Context->Esp = (ULONG) InitialSp - sizeof(PVOID);
if ( ContextType == BaseContextTypeThread ) {
Context->Eip = (ULONG) BaseThreadStartThunk;
} else if ( ContextType == BaseContextTypeFiber ) {
Context->Esp -= sizeof(PVOID);
*(PULONG)Context->Esp = (ULONG) BaseFiberStart;
Context->ContextFlags |= ContextFlags;
//
// If context switching of the floating state is specified, then
// initialize the floating context.
//
if (ContextFlags == CONTEXT_FLOATING_POINT) {
Context->FloatSave.ControlWord = 0x27f;
Context->FloatSave.StatusWord = 0;
Context->FloatSave.TagWord = 0xffff;
Context->FloatSave.ErrorOffset = 0;
Context->FloatSave.ErrorSelector = 0;
Context->FloatSave.DataOffset = 0;
Context->FloatSave.DataSelector = 0;
if (USER_SHARED_DATA->ProcessorFeatures[PF_XMMI_INSTRUCTIONS_AVAILABLE] != FALSE) {
Context->Dr6 = 0x1f80;
}
}
} else {
Context->Eip = (ULONG) BaseProcessStartThunk;
}
return;
}
VOID
BaseFiberStart(
VOID
)
/*++
Routine Description:
This function is called to start a Win32 fiber. Its purpose
is to call BaseThreadStart, getting the necessary arguments
from the fiber context record.
Arguments:
None.
Return Value:
None.
--*/
{
PFIBER Fiber;
Fiber = GetCurrentFiber();
BaseThreadStart( (LPTHREAD_START_ROUTINE)Fiber->FiberContext.Eax,
(LPVOID)Fiber->FiberContext.Ebx );
}