add support#24 loader is dynamic library

Author: pkujhd

Diff for: dymcode.go

@@ -313,7 +313,7 @@ func (linker *Linker) addSymbolMap(symPtr map[string]uintptr, codeModule *CodeMo
 				return nil, fmt.Errorf("unresolve external:%s", sym.Name)
 			}
 		} else if sym.Name == TLSNAME {
-			regTLS(symbolMap, sym.Offset)
+			//nothing todo
 		} else if sym.Kind == STEXT {
 			symbolMap[name] = uintptr(linker.symMap[name].Offset + segment.codeBase)
 			codeModule.Syms[sym.Name] = uintptr(symbolMap[name])
@@ -493,6 +493,9 @@ func (linker *Linker) relocate(codeModule *CodeModule, symbolMap map[string]uint
 			if addr != InvalidHandleValue {
 				switch loc.Type {
 				case R_TLS_LE:
+					if _, ok := symbolMap[TLSNAME]; !ok {
+						regTLS(symbolMap, segment.codeByte[symbol.Offset:loc.Offset])
+					}
 					binary.LittleEndian.PutUint32(segment.codeByte[loc.Offset:], uint32(symbolMap[TLSNAME]))
 				case R_CALL:
 					relocateCALL(addr, loc, segment, relocByte, addrBase)

Diff for: register.go

@@ -36,12 +36,20 @@ func typelinksinit(symPtr map[string]uintptr) {
 	registerFunc(&md, symPtr)
 }
 
+func RegSymbolWithSo(symPtr map[string]uintptr, path string) error {
+	return regSymbol(symPtr, path)
+}
+
 func RegSymbol(symPtr map[string]uintptr) error {
-	exe, err := os.Executable()
+	path, err := os.Executable()
 	if err != nil {
 		return err
 	}
-	f, err := objfile.Open(exe)
+	return regSymbol(symPtr, path)
+}
+
+func regSymbol(symPtr map[string]uintptr, path string) error {
+	f, err := objfile.Open(path)
 	if err != nil {
 		return err
 	}
@@ -69,13 +77,30 @@ func RegSymbol(symPtr map[string]uintptr) error {
 	return nil
 }
 
-func regTLS(symPtr map[string]uintptr, offset int) {
+func regTLS(symPtr map[string]uintptr, oper []byte) {
 	//FUNCTION HEADER
 	//x86/amd64
 	//asm:		MOVQ (TLS), CX
-	//bytes:	0x488b0c2500000000
+	//bytes:	0x64488b0c2500000000	or	0x65488b0c2500000000
+	//FS(0x64) or GS(0x65) segment register, on golang 1.8, FS/GS all generate.
+	//asm:		MOVQ OFF(IP), CX
+	//bytes:	0x488b0d00000000
+	//MOVQ OFF(IP), CX will be generated when goloader is a c-typed dynamic lib(only on linux/amd64)
 	funcptr := getFunctionPtr(regTLS)
-	tlsptr := *(*uint32)(adduintptr(funcptr, offset))
+	for i := 0; i < len(oper); i++ {
+		if *(*byte)(adduintptr(funcptr, i)) != oper[i] {
+			//function header modified
+			if *(*uint32)(unsafe.Pointer(funcptr))&0x00FFFFFF == 0x000d8b48 {
+				ptr := *(*uint32)(adduintptr(funcptr, 3))
+				ptr = *(*uint32)(adduintptr(funcptr, int(ptr)+7))
+				symPtr[TLSNAME] = uintptr(ptr)
+				return
+			} else {
+				panic("function header modified, can not relocate TLS")
+			}
+		}
+	}
+	tlsptr := *(*uint32)(adduintptr(funcptr, len(oper)))
 	symPtr[TLSNAME] = uintptr(tlsptr)
 }