relocate.go

package goloader

import (
	"cmd/objfile/objabi"
	"encoding/binary"
	"fmt"
	"github.com/eh-steve/goloader/obj"
	"github.com/eh-steve/goloader/objabi/reloctype"
	"github.com/eh-steve/goloader/objabi/symkind"
	"github.com/eh-steve/goloader/objabi/tls"
	"strings"
	"unsafe"
)

var (
	maxExtraInstructionBytesADRP            = int(unsafe.Sizeof(armLDRCode8Bytes)) + len(arm64Bcode) + PtrSize
	maxExtraInstructionBytesADRPLDST        = int(unsafe.Sizeof(armLDRCode8Bytes)) + int(unsafe.Sizeof(armLDRCode12Bytes)) + len(arm64Bcode) + PtrSize
	maxExtraInstructionBytesCALLARM64       = len(arm64CALLCode) + PtrSize
	maxExtraInstructionBytesPCRELxLEAQ      = PtrSize
	maxExtraInstructionBytesPCRELxMOVShort  = len(x86amd64replaceMOVQcode) + len(x86amd64JMPShortCode)
	maxExtraInstructionBytesPCRELxMOVNear   = len(x86amd64replaceMOVQcode) + len(x86amd64JMPNearCode)
	maxExtraInstructionBytesPCRELxCMPLShort = len(x86amd64replaceCMPLcode) + len(x86amd64JMPShortCode)
	maxExtraInstructionBytesPCRELxCMPLNear  = len(x86amd64replaceCMPLcode) + len(x86amd64JMPNearCode)
	maxExtraInstructionBytesPCRELxCALL2     = PtrSize
	maxExtraInstructionBytesPCRELxJMP       = len(x86amd64JMPLcode) + PtrSize
	maxExtraInstructionBytesCALLShort       = len(x86amd64CALLFarCode) + len(x86amd64JMPShortCode) + PtrSize
	maxExtraInstructionBytesCALLNear        = len(x86amd64CALLFarCode) + len(x86amd64JMPNearCode) + PtrSize
	maxExtraInstructionBytesGOTPCREL        = PtrSize
	maxExtraInstructionBytesARM64GOTPCREL   = PtrSize
)

func (linker *Linker) relocateADRP(mCode []byte, loc obj.Reloc, segment *segment, symAddr uintptr) (err error) {
	byteorder := linker.Arch.ByteOrder
	signedOffset := int64(symAddr) + int64(loc.Add) - ((int64(segment.codeBase) + int64(loc.Offset)) &^ 0xFFF)
	if oldMcode, ok := linker.appliedADRPRelocs[&mCode[0]]; !ok {
		linker.appliedADRPRelocs[&mCode[0]] = make([]byte, 8)
		copy(linker.appliedADRPRelocs[&mCode[0]], mCode)
	} else {
		copy(mCode, oldMcode)
	}
	epilogueOffset := loc.EpilogueOffset
	copy(segment.codeByte[epilogueOffset:epilogueOffset+loc.EpilogueSize], createARM64Nops(loc.EpilogueSize))

	if loc.Type == reloctype.R_ARM64_GOTPCREL || loc.Type == reloctype.R_ARM64_TLS_IE {
		epilogueToRelocDistance := epilogueOffset - loc.Offset
		if epilogueToRelocDistance < 0 || epilogueToRelocDistance > 1<<32 {
			return fmt.Errorf("unexpected R_ARM64_GOTPCREL relocation with negative or >32-bit offset %d: %s", epilogueToRelocDistance, loc.Sym.Name)
		}
		signedOffset = int64(alignof((segment.codeBase+epilogueOffset)-((segment.codeBase+loc.Offset)&^0xFFF), PtrSize))
		putAddress(byteorder, mCode[epilogueToRelocDistance:], uint64(symAddr+uintptr(loc.Add)))
	}
	// R_ADDRARM64 relocs include 2x 32 bit instructions, one ADRP, and one ADD/LDR/STR - both contain the destination register in the lowest 5 bits
	if signedOffset > 1<<32 || signedOffset < -1<<32 || (linker.options.ForceTestRelocationEpilogues && loc.EpilogueSize > 0 && !(loc.Type == reloctype.R_ARM64_GOTPCREL || loc.Type == reloctype.R_ARM64_TLS_IE)) {
		if loc.EpilogueSize == 0 {
			return fmt.Errorf("relocation epilogue not available but got a >32-bit ADRP reloc with offset %d: %s", signedOffset, loc.Sym.Name)
		}
		// Too far to fit inside an ADRP+ADD, do a jump to some extra code we add at the end big enough to fit any 64 bit address
		symAddr += uintptr(loc.Add)
		adrp := byteorder.Uint32(mCode)
		bcode := byteorder.Uint32(arm64Bcode) // Unconditional branch
		bcode |= ((uint32(epilogueOffset) - uint32(loc.Offset)) >> 2) & 0x01FFFFFF
		if epilogueOffset-loc.Offset < 0 {
			bcode |= 0x02000000 // 26th bit is sign bit
		}
		byteorder.PutUint32(mCode, bcode) // The second ADD/LD/ST instruction in the ADRP reloc will be bypassed as we return from the jump after it

		ldrCode8Bytes := armLDRCode8Bytes   // LDR PC+8
		ldrCode12Bytes := armLDRCode12Bytes // LDR PC+12
		ldrCode8Bytes |= adrp & 0x1F        // Set the register
		ldrCode12Bytes |= adrp & 0x1F       // Set the register

		if loc.Type == reloctype.R_ADDRARM64 {
			byteorder.PutUint32(segment.codeByte[epilogueOffset:], ldrCode8Bytes)
			epilogueOffset += Uint32Size
		} else {
			// must be LDR/STR reloc - the entire 64 bit address will be loaded in the register specified in the ADRP instruction,
			// so should be able to just append the LDR or STR immediately after
			byteorder.PutUint32(segment.codeByte[epilogueOffset:], ldrCode12Bytes)
			epilogueOffset += Uint32Size
			ldOrSt := byteorder.Uint32(mCode[4:])
			byteorder.PutUint32(segment.codeByte[epilogueOffset:], ldOrSt)
			epilogueOffset += Uint32Size
		}

		bcode = byteorder.Uint32(arm64Bcode)
		bcode |= ((uint32(loc.Offset) - uint32(epilogueOffset) + PtrSize) >> 2) & 0x01FFFFFF
		if loc.Offset-epilogueOffset+PtrSize < 0 {
			bcode |= 0x02000000
		}
		byteorder.PutUint32(segment.codeByte[epilogueOffset:], bcode)
		epilogueOffset += Uint32Size

		putAddressAddOffset(byteorder, segment.codeByte, &epilogueOffset, uint64(symAddr))
	} else {
		// Bit layout of ADRP instruction is:

		// 31  30  29  28  27  26  25  24  23  22  21  20  19  18  17  16  15  14  13  11  10  09  08  07  06  05  04  03  02  01  00
		// op  [imlo]   1   0   0   0   0  [<----------------------------- imm hi ----------------------------->]  [  dst register  ]

		// Bit layout of ADD instruction (64-bit) is:

		// 31  30  29  28  27  26  25  24  23  22  21  20  19  18  17  16  15  14  13  11  10  09  08  07  06  05  04  03  02  01  00
		//  1   0   0   1   0   0   0   1   0   0  [<--------------- imm12 ---------------->]  [  src register  ]  [  dst register  ]
		// sf <- 64 bit                        sh <- whether to left shift imm12 by 12 bits

		immLow := uint32((uint64(signedOffset)>>12)&3) << 29
		immHigh := uint32((uint64(signedOffset)>>12>>2)&0x7FFFF) << 5
		adrp := byteorder.Uint32(mCode[0:4])
		adrp |= immLow | immHigh
		addOrLdOrSt := byteorder.Uint32(mCode[4:8])
		switch loc.Type {
		case reloctype.R_ADDRARM64, reloctype.R_ARM64_PCREL_LDST8:
			addOrLdOrSt |= uint32(uint64(signedOffset)&0xFFF) << 10
		case reloctype.R_ARM64_PCREL_LDST16:
			if signedOffset&0x1 != 0 {
				err = fmt.Errorf("offset for 16-bit load/store has unaligned value %d", signedOffset&0xFFF)
			}
			addOrLdOrSt |= (uint32(signedOffset&0xFFF) >> 1) << 10
		case reloctype.R_ARM64_PCREL_LDST32:
			if signedOffset&0x3 != 0 {
				err = fmt.Errorf("offset for 32-bit load/store has unaligned value %d", signedOffset&0xFFF)
			}
			addOrLdOrSt |= (uint32(signedOffset&0xFFF) >> 2) << 10
		case reloctype.R_ARM64_PCREL_LDST64, reloctype.R_ARM64_GOTPCREL, reloctype.R_ARM64_TLS_IE:
			if signedOffset&0x7 != 0 {
				err = fmt.Errorf("offset for 64-bit load/store has unaligned value %d", signedOffset&0xFFF)
			}
			addOrLdOrSt |= (uint32(signedOffset&0xFFF) >> 3) << 10
		}
		byteorder.PutUint32(mCode, adrp)
		byteorder.PutUint32(mCode[4:], addOrLdOrSt)
	}
	return err
}

func (linker *Linker) relocateCALL(addr uintptr, loc obj.Reloc, segment *segment, relocByte []byte, addrBase int) error {
	byteorder := linker.Arch.ByteOrder
	offset := int(addr) - (addrBase + loc.Offset + loc.Size) + loc.Add
	epilogueOffset := loc.EpilogueOffset
	copy(segment.codeByte[epilogueOffset:epilogueOffset+loc.EpilogueSize], createX86Nops(loc.EpilogueSize))

	if offset > 0x7FFFFFFF || offset < -0x80000000 || (linker.options.ForceTestRelocationEpilogues && loc.EpilogueSize > 0) {
		// JMP into the epilogue, then CALL into the actual func using a PCREL 8 byte address placed after the JMP back from the epilogue
		if loc.EpilogueSize == 0 {
			return fmt.Errorf("relocation epilogue not available but got a >32-bit CALL reloc (x86 code: %x) with offset %d: %s", relocByte[loc.Offset-2:loc.Offset+loc.Size], offset, loc.Sym.Name)
		}
		// Replace the E8 CALL with a E9 JMP into the epilogue, the CALL the function, then JMP (near or far) back
		relocByte[loc.Offset-1] = x86amd64JMPcode
		offset = (segment.codeBase + epilogueOffset) - (addrBase + loc.Offset + loc.Size) // Point the JMP offset at the epilogue
		copy(segment.codeByte[epilogueOffset:], x86amd64CALLFarCode)
		epilogueOffset += len(x86amd64CALLFarCode)
		returnOffset := (loc.Offset + loc.Size) - epilogueOffset - len(x86amd64JMPShortCode) // assumes short jump - if we need a near jump, we'll adjust
		if returnOffset > -0x80 && returnOffset < 0 {
			byteorder.PutUint32(relocByte[epilogueOffset-4:], uint32(len(x86amd64JMPShortCode))) // Read the 8 bytes after the length of the JMP back
			copy(segment.codeByte[epilogueOffset:], x86amd64JMPShortCode)
			segment.codeByte[epilogueOffset+1] = uint8(returnOffset)
			epilogueOffset += len(x86amd64JMPShortCode)
		} else {
			byteorder.PutUint32(relocByte[epilogueOffset-4:], uint32(len(x86amd64JMPNearCode))) // Read the 8 bytes after the length of the JMP back
			returnOffset -= len(x86amd64JMPNearCode) - len(x86amd64JMPShortCode)
			copy(segment.codeByte[epilogueOffset:], x86amd64JMPNearCode)
			byteorder.PutUint32(segment.codeByte[epilogueOffset+1:], uint32(returnOffset))
			epilogueOffset += len(x86amd64JMPNearCode)
		}
		putAddressAddOffset(byteorder, segment.codeByte, &epilogueOffset, uint64(addr)+uint64(loc.Add))
	}
	byteorder.PutUint32(relocByte[loc.Offset:], uint32(offset))
	return nil
}

func (linker *Linker) relocateGOTPCREL(addr uintptr, loc obj.Reloc, relocByte []byte) {
	putAddress(linker.Arch.ByteOrder, relocByte[loc.EpilogueOffset:], uint64(addr))
	linker.Arch.ByteOrder.PutUint32(relocByte[loc.Offset:], uint32(loc.EpilogueOffset-loc.Offset-loc.Size))
}

func (linker *Linker) relocatePCREL(addr uintptr, loc obj.Reloc, segment *segment, relocByte []byte, addrBase int) (err error) {
	byteorder := linker.Arch.ByteOrder
	offset := int(addr) - (addrBase + loc.Offset + loc.Size) + loc.Add
	epilogueOffset := loc.EpilogueOffset
	if oldMcode, ok := linker.appliedPCRelRelocs[&relocByte[loc.Offset]]; !ok {
		linker.appliedPCRelRelocs[&relocByte[loc.Offset]] = make([]byte, loc.Size+2)
		copy(linker.appliedPCRelRelocs[&relocByte[loc.Offset]], relocByte[loc.Offset-2:])
	} else {
		copy(relocByte[loc.Offset-2:], oldMcode)
	}
	copy(segment.codeByte[epilogueOffset:epilogueOffset+loc.EpilogueSize], createX86Nops(loc.EpilogueSize))

	if offset > 0x7FFFFFFF || offset < -0x80000000 || (linker.options.ForceTestRelocationEpilogues && loc.EpilogueSize > 0) {
		if loc.EpilogueSize == 0 {
			return fmt.Errorf("relocation epilogue not available but got a >32-bit PCREL reloc (x86 code: %x) with offset %d: %s", relocByte[loc.Offset-3:loc.Offset+loc.Size], offset, loc.Sym.Name)
		}
		extraJMPDistance := 0
		relocOffsetIdx := 0
		cmplComparator := relocByte[loc.Offset+loc.Size]
		relocToEpilogueOffset := (segment.codeBase + epilogueOffset) - (addrBase + loc.Offset + loc.Size)
		bytes := relocByte[loc.Offset-2:]
		opcode := relocByte[loc.Offset-2]
		rexPrefix := relocByte[loc.Offset-3]
		dstRegister := ZeroByte

		if opcode == x86amd64LEAcode {
			bytes[0] = x86amd64MOVcode
			relocOffsetIdx = 2
		} else if opcode == x86amd64MOVcode {
			dstRegister = ((relocByte[loc.Offset-1] >> 3) & 0x7) | ((rexPrefix & 0x4) << 1) // rex prefix encodes high bit of dst register in bit 3
			srcRegister := relocByte[loc.Offset-1] & 0x7
			if srcRegister != 0x5 { // 0x5 == PC (RIP) register - if it's not a PCREL address, then that's an unexpected MOV instruction using an R_PCREL reloc
				return fmt.Errorf("unexpected src register %x (not RIP) for MOV PCREL reloc (x86 code: %x) with offset %d: %s", relocByte[loc.Offset-1], relocByte[loc.Offset-3:loc.Offset+loc.Size], offset, loc.Sym.Name)
			}
			copy(bytes, append(x86amd64JMPNearCode, x86amd64NOPcode))
			relocOffsetIdx = 1
		} else if opcode == x86amd64CMPLcode {
			copy(bytes, append(x86amd64JMPNearCode, x86amd64NOPcode, x86amd64NOPcode))
			relocOffsetIdx = 1
		} else if opcode == x86amd64CALL2code {
			// Probably a CGo FF15 call - CALL into the epilogue, then immediately JMP into function, then RET will bring us back to callsite
			relocOffsetIdx = 2
		} else if (bytes[1] == x86amd64CALLcode) && binary.LittleEndian.Uint32(relocByte[loc.Offset:]) == 0 {
			// Probably a CGo call - CALL into the epilogue, then immediately JMP into function, then RET will bring us back to callsite
			opcode = bytes[1]
			relocOffsetIdx = 2
		} else if bytes[1] == x86amd64JMPcode {
			// Also a CGo call
			opcode = bytes[1]
			relocOffsetIdx = 2
		} else {
			return fmt.Errorf("do not support x86 opcode: %x for symbol %s (offset %d)!\n", relocByte[loc.Offset-2:loc.Offset+loc.Size], loc.Sym.Name, offset)
		}
		extraJMPDistance = 2 - relocOffsetIdx
		byteorder.PutUint32(bytes[relocOffsetIdx:], uint32(relocToEpilogueOffset+extraJMPDistance))
		switch opcode {
		case x86amd64CMPLcode:
			copy(segment.codeByte[epilogueOffset:], x86amd64replaceCMPLcode)
			segment.codeByte[epilogueOffset+14] = cmplComparator // The 8 bit number to compare against
			putAddress(linker.Arch.ByteOrder, segment.codeByte[epilogueOffset+3:], uint64(addr+uintptr(loc.Add+extraJMPDistance)))
			epilogueOffset += len(x86amd64replaceCMPLcode)
		case x86amd64MOVcode:
			if dstRegister == 0x00 { // RAX
				copy(segment.codeByte[epilogueOffset:], x86amd64replaceMOVQcodeRAX)
				putAddress(linker.Arch.ByteOrder, segment.codeByte[epilogueOffset+2:], uint64(addr+uintptr(loc.Add)))
				epilogueOffset += len(x86amd64replaceMOVQcodeRAX)
			} else {
				copy(segment.codeByte[epilogueOffset:], x86amd64replaceMOVQcode)
				putAddress(linker.Arch.ByteOrder, segment.codeByte[epilogueOffset+3:], uint64(addr+uintptr(loc.Add)))
				segment.codeByte[epilogueOffset+11] |= (dstRegister & 0x8) >> 1
				segment.codeByte[epilogueOffset+13] = (dstRegister & 0x7) << 3
				epilogueOffset += len(x86amd64replaceMOVQcode)
			}
		case x86amd64CALLcode:
			bytes[1] = x86amd64JMPcode
			offset = (segment.codeBase + epilogueOffset) - (addrBase + loc.Offset + loc.Size) // Point the JMP offset at the epilogue
			copy(segment.codeByte[epilogueOffset:], x86amd64CALLFarCode)
			epilogueOffset += len(x86amd64CALLFarCode)
			returnOffset := (loc.Offset + loc.Size) - epilogueOffset - len(x86amd64JMPShortCode) // assumes short jump - if we need a near jump, we'll adjust
			if returnOffset > -0x80 && returnOffset < 0 {
				byteorder.PutUint32(relocByte[epilogueOffset-4:], uint32(len(x86amd64JMPShortCode))) // Read the 8 bytes after the length of the JMP back
				copy(segment.codeByte[epilogueOffset:], x86amd64JMPShortCode)
				segment.codeByte[epilogueOffset+1] = uint8(returnOffset)
				epilogueOffset += len(x86amd64JMPShortCode)
			} else {
				byteorder.PutUint32(relocByte[epilogueOffset-4:], uint32(len(x86amd64JMPNearCode))) // Read the 8 bytes after the length of the JMP back
				returnOffset -= len(x86amd64JMPNearCode) - len(x86amd64JMPShortCode)
				copy(segment.codeByte[epilogueOffset:], x86amd64JMPNearCode)
				byteorder.PutUint32(segment.codeByte[epilogueOffset+1:], uint32(returnOffset))
				epilogueOffset += len(x86amd64JMPNearCode)
			}
			putAddressAddOffset(byteorder, segment.codeByte, &epilogueOffset, uint64(addr)+uint64(loc.Add))
		case x86amd64CALL2code:
			putAddressAddOffset(byteorder, segment.codeByte, &epilogueOffset, uint64(addr)+uint64(loc.Add))
		case x86amd64JMPcode:
			copy(segment.codeByte[epilogueOffset:], x86amd64JMPLcode)
			epilogueOffset += len(x86amd64JMPLcode)
			putAddress(linker.Arch.ByteOrder, segment.codeByte[epilogueOffset:], uint64(addr+uintptr(loc.Add)))
			epilogueOffset += PtrSize
		case x86amd64LEAcode:
			putAddressAddOffset(byteorder, segment.codeByte, &epilogueOffset, uint64(addr+uintptr(loc.Add)))
		default:
			return fmt.Errorf("unexpected x86 opcode %x: %x for symbol %s (offset %d)!\n", opcode, relocByte[loc.Offset-2:loc.Offset+loc.Size], loc.Sym.Name, offset)
		}

		switch opcode {
		case x86amd64CMPLcode, x86amd64MOVcode:
			returnOffset := (loc.Offset + loc.Size) - epilogueOffset - len(x86amd64JMPShortCode) // assumes short jump - if we need a near jump, we'll adjust
			if returnOffset > -0x80 && returnOffset < 0 {
				copy(segment.codeByte[epilogueOffset:], x86amd64JMPShortCode)
				segment.codeByte[epilogueOffset+1] = uint8(returnOffset)
				epilogueOffset += len(x86amd64JMPShortCode)
			} else {
				returnOffset -= len(x86amd64JMPNearCode) - len(x86amd64JMPShortCode)
				copy(segment.codeByte[epilogueOffset:], x86amd64JMPNearCode)
				byteorder.PutUint32(segment.codeByte[epilogueOffset+1:], uint32(returnOffset))
				epilogueOffset += len(x86amd64JMPNearCode)
			}
		}
	} else {
		byteorder.PutUint32(relocByte[loc.Offset:], uint32(offset))
	}
	return err
}

func (linker *Linker) relocateCALLARM(addr uintptr, loc obj.Reloc, segment *segment) error {
	byteorder := linker.Arch.ByteOrder
	add := loc.Add
	if loc.Type == reloctype.R_CALLARM {
		add = int(signext24(int64(loc.Add&0xFFFFFF)) * 4)
	}
	epilogueOffset := loc.EpilogueOffset
	copy(segment.codeByte[epilogueOffset:epilogueOffset+loc.EpilogueSize], make([]byte, loc.EpilogueSize))
	offset := (int(addr) + add - (segment.codeBase + loc.Offset)) / 4
	if offset > 0x7FFFFF || offset < -0x800000 || (linker.options.ForceTestRelocationEpilogues && loc.EpilogueSize > 0) {
		if loc.EpilogueSize == 0 {
			return fmt.Errorf("relocation epilogue not available but got a >24-bit CALLARM reloc with offset %d: %s", offset, loc.Sym.Name)
		}
		off := uint32(epilogueOffset-loc.Offset) / 4
		if loc.Type == reloctype.R_CALLARM {
			add = int(signext24(int64(loc.Add&0xFFFFFF)+2) * 4)
			off = uint32(epilogueOffset-loc.Offset-8) / 4
		}
		putUint24(segment.codeByte[loc.Offset:], off)
		if loc.Type == reloctype.R_CALLARM64 {
			copy(segment.codeByte[epilogueOffset:], arm64CALLCode)
			epilogueOffset += len(arm64CALLCode)
		} else {
			copy(segment.codeByte[epilogueOffset:], armcode)
			epilogueOffset += len(armcode)
		}
		putAddressAddOffset(byteorder, segment.codeByte, &epilogueOffset, uint64(int(addr)+add))
	} else {
		val := byteorder.Uint32(segment.codeByte[loc.Offset:])
		if loc.Type == reloctype.R_CALLARM {
			val |= uint32(offset) & 0x00FFFFFF
		} else {
			val |= uint32(offset) & 0x03FFFFFF
		}
		byteorder.PutUint32(segment.codeByte[loc.Offset:], val)
	}
	return nil
}

func (linker *Linker) relocate(codeModule *CodeModule, symbolMap map[string]uintptr) (err error) {
	segment := &codeModule.segment
	byteorder := linker.Arch.ByteOrder

	for _, symbol := range linker.symMap {
		if linker.options.DumpTextBeforeAndAfterRelocs && linker.options.RelocationDebugWriter != nil && symbol.Kind == symkind.STEXT && symbol.Offset >= 0 {
			_, _ = fmt.Fprintf(linker.options.RelocationDebugWriter, "BEFORE RELOC (%x - %x) %142s: %x\n", codeModule.codeBase+symbol.Offset, codeModule.codeBase+symbol.Offset+symbol.Size, symbol.Name, codeModule.codeByte[symbol.Offset:symbol.Offset+symbol.Size])
		}
		for _, loc := range symbol.Reloc {
			addr := symbolMap[loc.Sym.Name]
			fmAddr, duplicated := symbolMap[FirstModulePrefix+loc.Sym.Name]
			if strings.HasPrefix(loc.Sym.Name, TypePrefix) && !duplicated {
				if variant, ok := symbolIsVariant(loc.Sym.Name); ok {
					fmAddr, duplicated = symbolMap[variant]
				}
			}
			if duplicated {
				isTypeWhichShouldNotBeDeduped := false
				for _, pkgPath := range linker.options.SkipTypeDeduplicationForPackages {
					if loc.Sym.Pkg == pkgPath {
						isTypeWhichShouldNotBeDeduped = true
					}
				}
				if !isTypeWhichShouldNotBeDeduped {
					// Always use the new module types initially - we will later check for type equality and
					// deduplicate them if they're structurally equal. If we used the firstmodule types here, there's a
					// risk they're not structurally equal, but it would be too late
					if !strings.HasPrefix(loc.Sym.Name, TypePrefix) {
						// If not a type, and not skipping deduplication for this package, use the firstmodule version
						addr = fmAddr
					}
				}
			}
			sym := loc.Sym
			relocByte := segment.dataByte
			addrBase := segment.dataBase
			if symbol.Kind == symkind.STEXT {
				addrBase = segment.codeBase
				relocByte = segment.codeByte
			}
			if strings.HasPrefix(sym.Name, ItabPrefix) {
				isItabWhichShouldNotBeDeduped := false
				for _, pkgPath := range linker.options.SkipTypeDeduplicationForPackages {
					if strings.HasPrefix(strings.TrimLeft(strings.TrimPrefix(sym.Name, ItabPrefix), "*"), pkgPath) {
						isItabWhichShouldNotBeDeduped = true
					}
				}
				if (addr == 0 || isItabWhichShouldNotBeDeduped) && linker.isSymbolReachable(sym.Name) {
					addr = uintptr(segment.dataBase + loc.Sym.Offset)
					symbolMap[loc.Sym.Name] = addr
					codeModule.module.itablinks = append(codeModule.module.itablinks, (*itab)(adduintptr(uintptr(segment.dataBase), loc.Sym.Offset)))
				}
			}

			if linker.options.RelocationDebugWriter != nil && loc.Offset != InvalidOffset {
				isDup := "    "
				if duplicated {
					isDup = "DUP "
				}
				var weakness string
				if loc.Type&reloctype.R_WEAK > 0 {
					weakness = "WEAK|"
				}
				relocType := weakness + objabi.RelocType(loc.Type&^reloctype.R_WEAK).String()
				_, _ = fmt.Fprintf(linker.options.RelocationDebugWriter, "RELOCATING %s %10s %10s %18s Base: 0x%x Pos: 0x%08x, Addr: 0x%016x AddrFromBase: %12d %s   to    %s\n",
					isDup, objabi.SymKind(symbol.Kind), objabi.SymKind(sym.Kind), relocType, addrBase, uintptr(unsafe.Pointer(&relocByte[loc.Offset])),
					addr, int(addr)-addrBase, symbol.Name, sym.Name)
			}

			if addr != InvalidHandleValue {
				switch loc.Type {
				case reloctype.R_ARM64_TLS_LE:
					if _, ok := symbolMap[TLSNAME]; !ok {
						symbolMap[TLSNAME] = tls.GetTLSOffset(linker.Arch, PtrSize)
					}
					v := symbolMap[TLSNAME] + 2*PtrSize
					if v < 0 || v >= 32678 {
						err = fmt.Errorf("got a R_ARM64_TLS_LE relocation inside %s (%s) with TLS offset out of range: %d", symbol.Name, loc.Sym.Name, v)
					}
					val := byteorder.Uint32(relocByte[loc.Offset:])
					val |= uint32(v) << 5
					byteorder.PutUint32(relocByte[loc.Offset:], val)
				case reloctype.R_TLS_LE:
					if _, ok := symbolMap[TLSNAME]; !ok {
						symbolMap[TLSNAME] = tls.GetTLSOffset(linker.Arch, PtrSize)
					}
					byteorder.PutUint32(relocByte[loc.Offset:], uint32(symbolMap[TLSNAME]))
				case reloctype.R_CALL, reloctype.R_CALL | reloctype.R_WEAK:
					err = linker.relocateCALL(addr, loc, segment, relocByte, addrBase)
				case reloctype.R_PCREL:
					if symbol.Kind != symkind.STEXT {
						err = fmt.Errorf("impossible! Sym: %s (target %s) is not in code segment! (kind %s)\n", symbol.Name, sym.Name, objabi.SymKind(sym.Kind))
						break
					}
					err = linker.relocatePCREL(addr, loc, segment, relocByte, addrBase)
				case reloctype.R_CALLARM, reloctype.R_CALLARM64, reloctype.R_CALLARM64 | reloctype.R_WEAK:
					err = linker.relocateCALLARM(addr, loc, segment)
				case reloctype.R_ADDRARM64, reloctype.R_ARM64_PCREL_LDST8, reloctype.R_ARM64_PCREL_LDST16, reloctype.R_ARM64_PCREL_LDST32, reloctype.R_ARM64_PCREL_LDST64, reloctype.R_ARM64_GOTPCREL:
					if symbol.Kind != symkind.STEXT {
						err = fmt.Errorf("impossible! Sym: %s is not in code segment! (kind %s)\n", sym.Name, objabi.SymKind(sym.Kind))
						break
					}
					err = linker.relocateADRP(relocByte[loc.Offset:], loc, segment, addr)
				case reloctype.R_ADDR, reloctype.R_WEAKADDR:
					address := uintptr(int(addr) + loc.Add)
					putAddress(byteorder, relocByte[loc.Offset:], uint64(address))
				case reloctype.R_CALLIND:
					// nothing todo
				case reloctype.R_ADDROFF, reloctype.R_WEAKADDROFF:
					offset := int(addr) - addrBase + loc.Add
					if offset > 0x7FFFFFFF || offset < -0x80000000 {
						err = fmt.Errorf("symName: %s offset for %s: %d overflows!\n", sym.Name, objabi.RelocType(loc.Type), offset)
					}
					byteorder.PutUint32(relocByte[loc.Offset:], uint32(offset))
				case reloctype.R_METHODOFF:
					if loc.Sym.Kind == symkind.STEXT {
						addrBase = segment.codeBase
					}
					offset := int(addr) - addrBase + loc.Add
					if offset > 0x7FFFFFFF || offset < -0x80000000 {
						err = fmt.Errorf("symName: %s offset for R_METHODOFF: %d overflows!\n", sym.Name, offset)
					}
					byteorder.PutUint32(relocByte[loc.Offset:], uint32(offset))
				case reloctype.R_GOTPCREL:
					linker.relocateGOTPCREL(addr, loc, relocByte)
				case reloctype.R_TLS_IE:
					if _, ok := symbolMap[TLSNAME]; !ok {
						symbolMap[TLSNAME] = tls.GetTLSOffset(linker.Arch, PtrSize)
					}
					linker.relocateGOTPCREL(symbolMap[TLSNAME], loc, relocByte)
				case reloctype.R_ARM64_TLS_IE:
					if _, ok := symbolMap[TLSNAME]; !ok {
						symbolMap[TLSNAME] = tls.GetTLSOffset(linker.Arch, PtrSize)
					}
					err = linker.relocateADRP(relocByte[loc.Offset:], loc, segment, addr)
				case reloctype.R_USETYPE:
					// nothing todo
				case reloctype.R_USEIFACE:
					// nothing todo
				case reloctype.R_USEIFACEMETHOD:
					// nothing todo
				case reloctype.R_ADDRCUOFF:
					// nothing todo
				case reloctype.R_KEEP:
					// nothing todo
				case reloctype.R_INITORDER:
					// nothing todo
				default:
					err = fmt.Errorf("unknown reloc type: %s sym: %s", objabi.RelocType(loc.Type).String(), sym.Name)
				}
			} else {
				if linker.isSymbolReachable(sym.Name) {
					panic(fmt.Sprintf("could not find address of symbol '%s' for relocation inside '%s'", loc.Sym.Name, sym.Name))
				}
			}
			if err != nil {
				return err
			}
		}
		if linker.options.DumpTextBeforeAndAfterRelocs && linker.options.RelocationDebugWriter != nil && symbol.Kind == symkind.STEXT && symbol.Offset >= 0 {
			_, _ = fmt.Fprintf(linker.options.RelocationDebugWriter, " AFTER RELOC (%x - %x) %142s : %x\n", codeModule.codeBase+symbol.Offset, codeModule.codeBase+symbol.Offset+symbol.Size, symbol.Name, codeModule.codeByte[symbol.Offset:symbol.Offset+symbol.Size])
		}
	}
	return err
}