debug/elf: support reading debug info from 32-bit PPC objects

Fixes #10118.

Change-Id: I4a2e6748db609c6eed1d68c824b81c59bd7b875c
Reviewed-on: https://go-review.googlesource.com/7590
Reviewed-by: Minux Ma <minux@golang.org>

diff --git a/src/debug/elf/file.go b/src/debug/elf/file.go
index 7e0dcc57a5dd9fed781d3d5989f4a7ca658bf47b..8e02c8bbd53b01d634c2dec40ad34ec7300eda10 100644 (file)
--- a/src/debug/elf/file.go
+++ b/src/debug/elf/file.go
@@ -533,6 +533,8 @@ func (f *File) applyRelocations(dst []byte, rels []byte) error {
                return f.applyRelocationsARM(dst, rels)
        case f.Class == ELFCLASS64 && f.Machine == EM_AARCH64:
                return f.applyRelocationsARM64(dst, rels)
+       case f.Class == ELFCLASS32 && f.Machine == EM_PPC:
+               return f.applyRelocationsPPC(dst, rels)
        case f.Class == ELFCLASS64 && f.Machine == EM_PPC64:
                return f.applyRelocationsPPC64(dst, rels)
        default:
@@ -713,6 +715,46 @@ func (f *File) applyRelocationsARM64(dst []byte, rels []byte) error {
        return nil
 }
 
+func (f *File) applyRelocationsPPC(dst []byte, rels []byte) error {
+       // 12 is the size of Rela32.
+       if len(rels)%12 != 0 {
+               return errors.New("length of relocation section is not a multiple of 12")
+       }
+
+       symbols, _, err := f.getSymbols(SHT_SYMTAB)
+       if err != nil {
+               return err
+       }
+
+       b := bytes.NewReader(rels)
+       var rela Rela32
+
+       for b.Len() > 0 {
+               binary.Read(b, f.ByteOrder, &rela)
+               symNo := rela.Info >> 8
+               t := R_PPC(rela.Info & 0xff)
+
+               if symNo == 0 || symNo > uint32(len(symbols)) {
+                       continue
+               }
+               sym := &symbols[symNo-1]
+               if SymType(sym.Info&0xf) != STT_SECTION {
+                       // We don't handle non-section relocations for now.
+                       continue
+               }
+
+               switch t {
+               case R_PPC_ADDR32:
+                       if rela.Off+4 >= uint32(len(dst)) || rela.Addend < 0 {
+                               continue
+                       }
+                       f.ByteOrder.PutUint32(dst[rela.Off:rela.Off+4], uint32(rela.Addend))
+               }
+       }
+
+       return nil
+}
+
 func (f *File) applyRelocationsPPC64(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 3e908bb1d085d50383908a420cf5c8ca2ea960ab..0d10ec51b1b6900da4ad9aa885fc367230325f5d 100644 (file)
--- a/src/debug/elf/file_test.go
+++ b/src/debug/elf/file_test.go
@@ -272,6 +272,12 @@ var relocationTests = []relocationTest{
                        {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-gcc5-ppc.obj",
+               []relocationTestEntry{
+                       {0, &dwarf.Entry{Offset: 0xb, Tag: dwarf.TagCompileUnit, Children: true, Field: []dwarf.Field{dwarf.Field{Attr: dwarf.AttrProducer, Val: "GNU C11 5.0.0 20150116 (experimental) -Asystem=linux -Asystem=unix -Asystem=posix -g"}, dwarf.Field{Attr: dwarf.AttrLanguage, Val: int64(12)}, dwarf.Field{Attr: dwarf.AttrName, Val: "go-relocation-test-gcc5-ppc.c"}, dwarf.Field{Attr: dwarf.AttrCompDir, Val: "/tmp"}, dwarf.Field{Attr: dwarf.AttrLowpc, Val: uint64(0x0)}, dwarf.Field{Attr: dwarf.AttrHighpc, Val: int64(0x44)}, dwarf.Field{Attr: dwarf.AttrStmtList, Val: int64(0)}}}},
+               },
+       },
        {
                "testdata/go-relocation-test-gcc482-ppc64le.obj",
                []relocationTestEntry{

diff --git a/src/debug/elf/testdata/go-relocation-test-gcc5-ppc.obj b/src/debug/elf/testdata/go-relocation-test-gcc5-ppc.obj
new file mode 100644 (file)
index 0000000..f4165af
Binary files /dev/null and b/src/debug/elf/testdata/go-relocation-test-gcc5-ppc.obj differ