re PR go/65417 (debug/elf: lacks support for PPC relocations)

	PR go/65417
debug/elf: support reading debug info from 32-bit PPC objects

This is a backport of http://golang.org/7590 from the master
Go library.

From-SVN: r221644

diff --git a/libgo/go/debug/elf/file.go b/libgo/go/debug/elf/file.go
index 5a418d8102163c2711c161fc2fb3e5d538eb0cf6..653b8d42400c3b25eb8541e1dd76fb32406e2dce 100644 (file)
--- a/libgo/go/debug/elf/file.go
+++ b/libgo/go/debug/elf/file.go
@@ -532,6 +532,9 @@ func (f *File) applyRelocations(dst []byte, rels []byte) error {
        if f.Class == ELFCLASS64 && f.Machine == EM_AARCH64 {
                return f.applyRelocationsARM64(dst, rels)
        }
+       if f.Class == ELFCLASS32 && f.Machine == EM_PPC {
+               return f.applyRelocationsPPC(dst, rels)
+       }
        if f.Class == ELFCLASS64 && f.Machine == EM_PPC64 {
                return f.applyRelocationsPPC64(dst, rels)
        }
@@ -677,6 +680,46 @@ 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/libgo/go/debug/elf/file_test.go b/libgo/go/debug/elf/file_test.go
index ce10da71d2b23c8959ea510b582fe27153fe535d..56e2604d9d3f24251a6f01778fb5ace724ddab84 100644 (file)
--- a/libgo/go/debug/elf/file_test.go
+++ b/libgo/go/debug/elf/file_test.go
@@ -260,6 +260,12 @@ var relocationTests = []relocationTest{
                        {0, &dwarf.Entry{Offset: 0xb, Tag: dwarf.TagCompileUnit, Children: true, Field: []dwarf.Field{{Attr: dwarf.AttrProducer, Val: "GNU C 4.2.4 (Ubuntu 4.2.4-1ubuntu4)"}, {Attr: dwarf.AttrLanguage, Val: int64(1)}, {Attr: dwarf.AttrName, Val: "go-relocation-test-gcc424.c"}, {Attr: dwarf.AttrCompDir, Val: "/tmp"}, {Attr: dwarf.AttrLowpc, Val: uint64(0x0)}, {Attr: dwarf.AttrHighpc, Val: uint64(0x6)}, {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/libgo/go/debug/elf/testdata/go-relocation-test-gcc5-ppc.obj b/libgo/go/debug/elf/testdata/go-relocation-test-gcc5-ppc.obj
new file mode 100644 (file)
index 0000000..f4165af
Binary files /dev/null and b/libgo/go/debug/elf/testdata/go-relocation-test-gcc5-ppc.obj differ