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// Licensed to the .NET Foundation under one or more agreements.
// The .NET Foundation licenses this file to you under the MIT license.
// See the LICENSE file in the project root for more information.
//
//
//
// File: remotingx86.cpp
//
//
//
// Purpose: Defines various remoting related functions for the x86 architecture
//
//
//
//
#include "common.h"
#ifdef FEATURE_REMOTING
#include "excep.h"
#include "comdelegate.h"
#include "remoting.h"
#include "field.h"
#include "siginfo.hpp"
#include "stackbuildersink.h"
#include "threads.h"
#include "method.hpp"
#include "asmconstants.h"
#include "interoputil.h"
#include "virtualcallstub.h"
#ifdef FEATURE_COMINTEROP
#include "comcallablewrapper.h"
#include "comcache.h"
#endif // FEATURE_COMINTEROP
//+----------------------------------------------------------------------------
//
// Method: CTPMethodTable::CreateThunkForVirtualMethod private
//
// Synopsis: Creates the thunk that pushes the supplied slot number and jumps
// to TP Stub
//
//+----------------------------------------------------------------------------
PCODE CTPMethodTable::CreateThunkForVirtualMethod(DWORD dwSlot, BYTE *startaddr)
{
CONTRACTL
{
NOTHROW;
GC_NOTRIGGER;
MODE_ANY;
PRECONDITION(CheckPointer(startaddr));
}
CONTRACTL_END;
BYTE *pCode = startaddr;
// 0000 B8 67 45 23 01 MOV EAX, dwSlot
// 0005 E9 ?? ?? ?? ?? JMP TransparentProxyStub
*pCode++ = 0xB8;
*((DWORD *) pCode) = dwSlot;
pCode += sizeof(DWORD);
*pCode++ = 0xE9;
// self-relative call, based on the start of the next instruction.
*((LONG *) pCode) = (LONG)((size_t)GetTPStubEntryPoint() - (size_t) (pCode + sizeof(LONG)));
_ASSERTE(CVirtualThunkMgr::IsThunkByASM((PCODE)startaddr));
return (PCODE)startaddr;
}
//+----------------------------------------------------------------------------
//
// Method: CTPMethodTable::ActivatePrecodeRemotingThunk private
//
// Synopsis: Patch the precode remoting thunk to begin interception
//
//+----------------------------------------------------------------------------
void CTPMethodTable::ActivatePrecodeRemotingThunk()
{
CONTRACTL
{
THROWS;
GC_TRIGGERS;
MODE_ANY;
}
CONTRACTL_END;
// Before activation:
// 0000 C3 ret
// 0001 90 nop
// After activation:
// 0000 85 C9 test ecx,ecx
// 0002 74 XX je RemotingDone
// 0004 81 39 XX XX XX XX cmp dword ptr [ecx],11111111h
// 000A 74 XX je RemotingCheck
// Switch offset and size of patch based on the jump opcode used.
BYTE* pCode = (BYTE*)PrecodeRemotingThunk;
SIZE_T mtOffset = 0x0006;
SIZE_T size = 0x000A;
// Patch "ret + nop" to "test ecx,ecx"
*(UINT16 *)pCode = 0xC985;
// Replace placeholder value with the actual address of TP method table
_ASSERTE(*(PVOID*)(pCode+mtOffset) == (PVOID*)0x11111111);
*(PVOID*)(pCode+mtOffset) = GetMethodTable();
FlushInstructionCache(GetCurrentProcess(), pCode, size);
}
//+----------------------------------------------------------------------------
//
// Method: CVirtualThunkMgr::DoTraceStub public
//
// Synopsis: Traces the stub given the starting address
//
//+----------------------------------------------------------------------------
BOOL CVirtualThunkMgr::DoTraceStub(PCODE stubStartAddress, TraceDestination *trace)
{
CONTRACTL
{
NOTHROW;
GC_NOTRIGGER;
MODE_ANY;
PRECONDITION(stubStartAddress != NULL);
PRECONDITION(CheckPointer(trace));
}
CONTRACTL_END;
BOOL bIsStub = FALSE;
// Find a thunk whose code address matching the starting address
LPBYTE pThunk = FindThunk((LPBYTE)stubStartAddress);
if(NULL != pThunk)
{
LPBYTE pbAddr = NULL;
LONG destAddress = 0;
if((LPBYTE)stubStartAddress == pThunk)
{
// Extract the long which gives the self relative address
// of the destination
pbAddr = pThunk + sizeof(BYTE) + sizeof(DWORD) + sizeof(BYTE);
destAddress = *(LONG *)pbAddr;
// Calculate the absolute address by adding the offset of the next
// instruction after the call instruction
destAddress += (LONG)(size_t)(pbAddr + sizeof(LONG));
}
// We cannot tell where the stub will end up until OnCall is reached.
// So we tell the debugger to run till OnCall is reached and then
// come back and ask us again for the actual destination address of
// the call
Stub *stub = Stub::RecoverStub((TADDR)destAddress);
trace->InitForFramePush(stub->GetPatchAddress());
bIsStub = TRUE;
}
return bIsStub;
}
//+----------------------------------------------------------------------------
//
// Method: CVirtualThunkMgr::IsThunkByASM public
//
// Synopsis: Check assembly to see if this one of our thunks
//
//+----------------------------------------------------------------------------
BOOL CVirtualThunkMgr::IsThunkByASM(PCODE startaddr)
{
CONTRACTL
{
NOTHROW;
GC_NOTRIGGER;
MODE_ANY;
PRECONDITION(startaddr != NULL);
}
CONTRACTL_END;
PTR_BYTE pbCode = PTR_BYTE(startaddr);
return ((pbCode[0] == 0xB8) &&
(pbCode[5] == 0xe9) &&
(rel32Decode((TADDR)(pbCode + 6)) == CTPMethodTable::GetTPStubEntryPoint()));
}
//+----------------------------------------------------------------------------
//
// Method: CVirtualThunkMgr::GetMethodDescByASM public
//
// Synopsis: Parses MethodDesc out of assembly code
//
//+----------------------------------------------------------------------------
MethodDesc *CVirtualThunkMgr::GetMethodDescByASM(PCODE startaddr, MethodTable *pMT)
{
CONTRACT (MethodDesc*)
{
NOTHROW;
GC_NOTRIGGER;
MODE_ANY;
PRECONDITION(startaddr != NULL);
PRECONDITION(CheckPointer(pMT));
POSTCONDITION(CheckPointer(RETVAL));
}
CONTRACT_END;
RETURN (pMT->GetMethodDescForSlot(*((DWORD *) (startaddr + 1))));
}
#endif// FEATURE_REMOTING
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