cmd/link: simplify PE relocations mapping

The code for mapping Windows PE relocations to Go relocations was
difficult to follow and contains some duplicated code. Also, it was
mapping IMAGE_REL_AMD64_ADDR32 to R_PCREL instead of R_ADDR.

This CL commit simplifies the code and fixes the mapping. I haven't been
able to coerce mingw-w64 to generate IMAGE_REL_AMD64_ADDR32 relocations,
so I haven't been able to test this change. However, the previous
implementation was clearly wrong.

While here, remove code supporting the unsupported windows/arm support.

Updates #71671
Updates #75485

Change-Id: Id0d6f352fa7d5df9e00509fcdf09ca0cb91ca524
Reviewed-on: https://go-review.googlesource.com/c/go/+/672155
Reviewed-by: Michael Knyszek <mknyszek@google.com>
Reviewed-by: Cherry Mui <cherryyz@google.com>
LUCI-TryBot-Result: Go LUCI <golang-scoped@luci-project-accounts.iam.gserviceaccount.com>

diff --git a/src/cmd/link/internal/loadpe/ldpe.go b/src/cmd/link/internal/loadpe/ldpe.go
index b895ac414941107c3f73b3dba67b8c3a94422c29..d3a050135c28286d5f7dff8744befcefa07846ad 100644 (file)
--- a/src/cmd/link/internal/loadpe/ldpe.go
+++ b/src/cmd/link/internal/loadpe/ldpe.go
@@ -17,6 +17,7 @@ import (
        "errors"
        "fmt"
        "io"
+       "strconv"
        "strings"
 )
 
@@ -348,11 +349,11 @@ func Load(l *loader.Loader, arch *sys.Arch, localSymVersion int, input *bio.Read
                                return nil, fmt.Errorf("relocation number %d symbol index idx=%d cannot be large then number of symbols %d", j, r.SymbolTableIndex, len(f.COFFSymbols))
                        }
                        pesym := &f.COFFSymbols[r.SymbolTableIndex]
-                       _, gosym, err := state.readpesym(pesym)
+                       _, rSym, err := state.readpesym(pesym)
                        if err != nil {
                                return nil, err
                        }
-                       if gosym == 0 {
+                       if rSym == 0 {
                                name, err := pesym.FullName(f.StringTable)
                                if err != nil {
                                        name = string(pesym.Name[:])
@@ -360,90 +361,53 @@ func Load(l *loader.Loader, arch *sys.Arch, localSymVersion int, input *bio.Read
                                return nil, fmt.Errorf("reloc of invalid sym %s idx=%d type=%d", name, r.SymbolTableIndex, pesym.Type)
                        }
 
-                       rSym := gosym
                        rSize := uint8(4)
                        rOff := int32(r.VirtualAddress)
-                       var rAdd int64
                        var rType objabi.RelocType
                        switch arch.Family {
                        default:
                                return nil, fmt.Errorf("%s: unsupported arch %v", pn, arch.Family)
-                       case sys.I386, sys.AMD64:
+                       case sys.I386:
                                switch r.Type {
-                               default:
-                                       return nil, fmt.Errorf("%s: %v: unknown relocation type %v", pn, state.sectsyms[rsect], r.Type)
-
-                               case IMAGE_REL_I386_REL32, IMAGE_REL_AMD64_REL32,
-                                       IMAGE_REL_AMD64_ADDR32, // R_X86_64_PC32
-                                       IMAGE_REL_AMD64_ADDR32NB:
-                                       if r.Type == IMAGE_REL_AMD64_ADDR32NB {
-                                               rType = objabi.R_PEIMAGEOFF
-                                       } else {
-                                               rType = objabi.R_PCREL
-                                       }
-
-                                       rAdd = int64(int32(binary.LittleEndian.Uint32(state.sectdata[rsect][rOff:])))
-
-                               case IMAGE_REL_I386_DIR32NB, IMAGE_REL_I386_DIR32:
-                                       if r.Type == IMAGE_REL_I386_DIR32NB {
-                                               rType = objabi.R_PEIMAGEOFF
-                                       } else {
-                                               rType = objabi.R_ADDR
-                                       }
-
-                                       // load addend from image
-                                       rAdd = int64(int32(binary.LittleEndian.Uint32(state.sectdata[rsect][rOff:])))
-
-                               case IMAGE_REL_AMD64_ADDR64: // R_X86_64_64
-                                       rSize = 8
-
+                               case IMAGE_REL_I386_REL32:
+                                       rType = objabi.R_PCREL
+                               case IMAGE_REL_I386_DIR32:
                                        rType = objabi.R_ADDR
-
-                                       // load addend from image
-                                       rAdd = int64(binary.LittleEndian.Uint64(state.sectdata[rsect][rOff:]))
+                               case IMAGE_REL_I386_DIR32NB:
+                                       rType = objabi.R_PEIMAGEOFF
                                }
-
-                       case sys.ARM:
+                       case sys.AMD64:
                                switch r.Type {
-                               default:
-                                       return nil, fmt.Errorf("%s: %v: unknown ARM relocation type %v", pn, state.sectsyms[rsect], r.Type)
-
-                               case IMAGE_REL_ARM_SECREL:
+                               case IMAGE_REL_AMD64_REL32:
                                        rType = objabi.R_PCREL
-
-                                       rAdd = int64(int32(binary.LittleEndian.Uint32(state.sectdata[rsect][rOff:])))
-
-                               case IMAGE_REL_ARM_ADDR32, IMAGE_REL_ARM_ADDR32NB:
-                                       if r.Type == IMAGE_REL_ARM_ADDR32NB {
-                                               rType = objabi.R_PEIMAGEOFF
-                                       } else {
-                                               rType = objabi.R_ADDR
-                                       }
-
-                                       rAdd = int64(int32(binary.LittleEndian.Uint32(state.sectdata[rsect][rOff:])))
-
-                               case IMAGE_REL_ARM_BRANCH24:
-                                       rType = objabi.R_CALLARM
-
-                                       rAdd = int64(int32(binary.LittleEndian.Uint32(state.sectdata[rsect][rOff:])))
+                               case IMAGE_REL_AMD64_ADDR32:
+                                       rType = objabi.R_ADDR
+                               case IMAGE_REL_AMD64_ADDR64:
+                                       rType = objabi.R_ADDR
+                                       rSize = 8
+                               case IMAGE_REL_AMD64_ADDR32NB:
+                                       rType = objabi.R_PEIMAGEOFF
                                }
-
                        case sys.ARM64:
                                switch r.Type {
-                               default:
-                                       return nil, fmt.Errorf("%s: %v: unknown ARM64 relocation type %v", pn, state.sectsyms[rsect], r.Type)
-
-                               case IMAGE_REL_ARM64_ADDR32, IMAGE_REL_ARM64_ADDR32NB:
-                                       if r.Type == IMAGE_REL_ARM64_ADDR32NB {
-                                               rType = objabi.R_PEIMAGEOFF
-                                       } else {
-                                               rType = objabi.R_ADDR
-                                       }
-
-                                       rAdd = int64(int32(binary.LittleEndian.Uint32(state.sectdata[rsect][rOff:])))
+                               case IMAGE_REL_ARM64_ADDR32:
+                                       rType = objabi.R_ADDR
+                               case IMAGE_REL_ARM64_ADDR32NB:
+                                       rType = objabi.R_PEIMAGEOFF
                                }
                        }
-
+                       if rType == 0 {
+                               return nil, fmt.Errorf("%s: %v: unknown relocation type %v", pn, state.sectsyms[rsect], r.Type)
+                       }
+                       var rAdd int64
+                       switch rSize {
+                       default:
+                               panic("unexpected relocation size " + strconv.Itoa(int(rSize)))
+                       case 4:
+                               rAdd = int64(int32(binary.LittleEndian.Uint32(state.sectdata[rsect][rOff:])))
+                       case 8:
+                               rAdd = int64(binary.LittleEndian.Uint64(state.sectdata[rsect][rOff:]))
+                       }
                        // ld -r could generate multiple section symbols for the
                        // same section but with different values, we have to take
                        // that into account, or in the case of split resources,