debug/elf: fix arm build

This change adds the minimum necessary to implement applyRelocations.

For adg, this code uses the switch statement.

Change-Id: I0989daab8d0e36c2a4f6a315ced258b832744616
Reviewed-on: https://go-review.googlesource.com/7266
Reviewed-by: Ian Lance Taylor <iant@golang.org>

diff --git a/src/debug/elf/file.go b/src/debug/elf/file.go
index b2174d4277f23fd5fa2b6ec219691b4f98d586f0..7e0dcc57a5dd9fed781d3d5989f4a7ca658bf47b 100644 (file)
--- a/src/debug/elf/file.go
+++ b/src/debug/elf/file.go
@@ -524,20 +524,20 @@ func (f *File) Section(name string) *Section {
 // applyRelocations applies relocations to dst. rels is a relocations section
 // in RELA format.
 func (f *File) applyRelocations(dst []byte, rels []byte) error {
-       if f.Class == ELFCLASS64 && f.Machine == EM_X86_64 {
+       switch {
+       case f.Class == ELFCLASS64 && f.Machine == EM_X86_64:
                return f.applyRelocationsAMD64(dst, rels)
-       }
-       if f.Class == ELFCLASS32 && f.Machine == EM_386 {
+       case f.Class == ELFCLASS32 && f.Machine == EM_386:
                return f.applyRelocations386(dst, rels)
-       }
-       if f.Class == ELFCLASS64 && f.Machine == EM_AARCH64 {
+       case f.Class == ELFCLASS32 && f.Machine == EM_ARM:
+               return f.applyRelocationsARM(dst, rels)
+       case f.Class == ELFCLASS64 && f.Machine == EM_AARCH64:
                return f.applyRelocationsARM64(dst, rels)
-       }
-       if f.Class == ELFCLASS64 && f.Machine == EM_PPC64 {
+       case f.Class == ELFCLASS64 && f.Machine == EM_PPC64:
                return f.applyRelocationsPPC64(dst, rels)
+       default:
+               return errors.New("applyRelocations: not implemented")
        }
-
-       return errors.New("not implemented")
 }
 
 func (f *File) applyRelocationsAMD64(dst []byte, rels []byte) error {
@@ -626,6 +626,44 @@ func (f *File) applyRelocations386(dst []byte, rels []byte) error {
        return nil
 }
 
+func (f *File) applyRelocationsARM(dst []byte, rels []byte) error {
+       // 8 is the size of Rel32.
+       if len(rels)%8 != 0 {
+               return errors.New("length of relocation section is not a multiple of 8")
+       }
+
+       symbols, _, err := f.getSymbols(SHT_SYMTAB)
+       if err != nil {
+               return err
+       }
+
+       b := bytes.NewReader(rels)
+       var rel Rel32
+
+       for b.Len() > 0 {
+               binary.Read(b, f.ByteOrder, &rel)
+               symNo := rel.Info >> 8
+               t := R_ARM(rel.Info & 0xff)
+
+               if symNo == 0 || symNo > uint32(len(symbols)) {
+                       continue
+               }
+               sym := &symbols[symNo-1]
+
+               switch t {
+               case R_ARM_REL32:
+                       if rel.Off+4 >= uint32(len(dst)) {
+                               continue
+                       }
+                       val := f.ByteOrder.Uint32(dst[rel.Off : rel.Off+4])
+                       val += uint32(sym.Value)
+                       f.ByteOrder.PutUint32(dst[rel.Off:rel.Off+4], val)
+               }
+       }
+
+       return nil
+}
+
 func (f *File) applyRelocationsARM64(dst []byte, rels []byte) error {
        // 24 is the size of Rela64.
        if len(rels)%24 != 0 {

diff --git a/src/debug/elf/file_test.go b/src/debug/elf/file_test.go
index d57aaab0ec2630fe7c8420792b2a920bb7e23818..3e908bb1d085d50383908a420cf5c8ca2ea960ab 100644 (file)
--- a/src/debug/elf/file_test.go
+++ b/src/debug/elf/file_test.go
@@ -266,6 +266,12 @@ var relocationTests = []relocationTest{
                        {0, &dwarf.Entry{Offset: 0xb, Tag: dwarf.TagCompileUnit, Children: true, Field: []dwarf.Field{{Attr: dwarf.AttrProducer, Val: "GNU C 4.8.2 -g -fstack-protector"}, {Attr: dwarf.AttrLanguage, Val: int64(1)}, {Attr: dwarf.AttrName, Val: "go-relocation-test-gcc482.c"}, {Attr: dwarf.AttrCompDir, Val: "/tmp"}, {Attr: dwarf.AttrLowpc, Val: uint64(0x0)}, {Attr: dwarf.AttrHighpc, Val: int64(0x24)}, {Attr: dwarf.AttrStmtList, Val: int64(0)}}}},
                },
        },
+       {
+               "testdata/go-relocation-test-gcc492-arm.obj",
+               []relocationTestEntry{
+                       {0, &dwarf.Entry{Offset: 0xb, Tag: dwarf.TagCompileUnit, Children: true, Field: []dwarf.Field{{Attr: dwarf.AttrProducer, Val: "GNU C 4.9.2 20141224 (prerelease) -march=armv7-a -mfloat-abi=hard -mfpu=vfpv3-d16 -mtls-dialect=gnu -g"}, {Attr: dwarf.AttrLanguage, Val: int64(1)}, {Attr: dwarf.AttrName, Val: "go-relocation-test-gcc492.c"}, {Attr: dwarf.AttrCompDir, Val: "/root/go/src/debug/elf/testdata"}, {Attr: dwarf.AttrLowpc, Val: uint64(0x0)}, {Attr: dwarf.AttrHighpc, Val: int64(0x28)}, {Attr: dwarf.AttrStmtList, Val: int64(0)}}}},
+               },
+       },
        {
                "testdata/go-relocation-test-gcc482-ppc64le.obj",
                []relocationTestEntry{

diff --git a/src/debug/elf/testdata/go-relocation-test-gcc492-arm.obj b/src/debug/elf/testdata/go-relocation-test-gcc492-arm.obj
new file mode 100644 (file)
index 0000000..ed45be2
Binary files /dev/null and b/src/debug/elf/testdata/go-relocation-test-gcc492-arm.obj differ