debug/elf: add support for GOARCH=mips{,le}

Change-Id: Ia6f8ae7e56a49ad66b60a24c4afb606f3cfe5efd
Reviewed-on: https://go-review.googlesource.com/31482
Run-TryBot: Brad Fitzpatrick <bradfitz@golang.org>
Reviewed-by: Cherry Zhang <cherryyz@google.com>

diff --git a/src/debug/elf/file.go b/src/debug/elf/file.go
index c1cbfa6225415ec0d2ce988025e1ba62c8c9b7fc..0c547669a9a705e105b87fa80e9dd1cfe88ed7cc 100644 (file)
--- a/src/debug/elf/file.go
+++ b/src/debug/elf/file.go
@@ -579,7 +579,7 @@ func (f *File) Section(name string) *Section {
 }
 
 // applyRelocations applies relocations to dst. rels is a relocations section
-// in RELA format.
+// in REL or RELA format.
 func (f *File) applyRelocations(dst []byte, rels []byte) error {
        switch {
        case f.Class == ELFCLASS64 && f.Machine == EM_X86_64:
@@ -594,6 +594,8 @@ func (f *File) applyRelocations(dst []byte, rels []byte) error {
                return f.applyRelocationsPPC(dst, rels)
        case f.Class == ELFCLASS64 && f.Machine == EM_PPC64:
                return f.applyRelocationsPPC64(dst, rels)
+       case f.Class == ELFCLASS32 && f.Machine == EM_MIPS:
+               return f.applyRelocationsMIPS(dst, rels)
        case f.Class == ELFCLASS64 && f.Machine == EM_MIPS:
                return f.applyRelocationsMIPS64(dst, rels)
        case f.Class == ELFCLASS64 && f.Machine == EM_S390:
@@ -863,6 +865,44 @@ func (f *File) applyRelocationsPPC64(dst []byte, rels []byte) error {
        return nil
 }
 
+func (f *File) applyRelocationsMIPS(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_MIPS(rel.Info & 0xff)
+
+               if symNo == 0 || symNo > uint32(len(symbols)) {
+                       continue
+               }
+               sym := &symbols[symNo-1]
+
+               switch t {
+               case R_MIPS_32:
+                       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) applyRelocationsMIPS64(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 f1e28a067159c772cf0249e48520c7f498aec41c..58bdf277d36b39ae495febfe8c2d1b58781c41a2 100644 (file)
--- a/src/debug/elf/file_test.go
+++ b/src/debug/elf/file_test.go
@@ -510,6 +510,44 @@ var relocationTests = []relocationTest{
                        }},
                },
        },
+       {
+               "testdata/go-relocation-test-gcc492-mipsle.obj",
+               []relocationTestEntry{
+                       {0, &dwarf.Entry{
+                               Offset:   0xb,
+                               Tag:      dwarf.TagCompileUnit,
+                               Children: true,
+                               Field: []dwarf.Field{
+                                       {Attr: dwarf.AttrProducer, Val: "GNU C 4.9.2 -mel -march=mips2 -mtune=mips32 -mllsc -mno-shared -mabi=32 -g", Class: dwarf.ClassString},
+                                       {Attr: dwarf.AttrLanguage, Val: int64(1), Class: dwarf.ClassConstant},
+                                       {Attr: dwarf.AttrName, Val: "hello.c", Class: dwarf.ClassString},
+                                       {Attr: dwarf.AttrCompDir, Val: "/tmp", Class: dwarf.ClassString},
+                                       {Attr: dwarf.AttrLowpc, Val: uint64(0x0), Class: dwarf.ClassAddress},
+                                       {Attr: dwarf.AttrHighpc, Val: int64(0x58), Class: dwarf.ClassConstant},
+                                       {Attr: dwarf.AttrStmtList, Val: int64(0), Class: dwarf.ClassLinePtr},
+                               },
+                       }},
+               },
+       },
+       {
+               "testdata/go-relocation-test-gcc540-mips.obj",
+               []relocationTestEntry{
+                       {0, &dwarf.Entry{
+                               Offset:   0xb,
+                               Tag:      dwarf.TagCompileUnit,
+                               Children: true,
+                               Field: []dwarf.Field{
+                                       {Attr: dwarf.AttrProducer, Val: "GNU C11 5.4.0 20160609 -meb -mips32 -mtune=mips32r2 -mfpxx -mllsc -mno-shared -mabi=32 -g -gdwarf-2", Class: dwarf.ClassString},
+                                       {Attr: dwarf.AttrLanguage, Val: int64(12), Class: dwarf.ClassConstant},
+                                       {Attr: dwarf.AttrName, Val: "hello.c", Class: dwarf.ClassString},
+                                       {Attr: dwarf.AttrCompDir, Val: "/tmp", Class: dwarf.ClassString},
+                                       {Attr: dwarf.AttrLowpc, Val: uint64(0x0), Class: dwarf.ClassAddress},
+                                       {Attr: dwarf.AttrHighpc, Val: uint64(0x5c), Class: dwarf.ClassAddress},
+                                       {Attr: dwarf.AttrStmtList, Val: int64(0), Class: dwarf.ClassLinePtr},
+                               },
+                       }},
+               },
+       },
        {
                "testdata/go-relocation-test-gcc493-mips64le.obj",
                []relocationTestEntry{

diff --git a/src/debug/elf/testdata/go-relocation-test-gcc492-mipsle.obj b/src/debug/elf/testdata/go-relocation-test-gcc492-mipsle.obj
new file mode 100644 (file)
index 0000000..a5fbcfb
Binary files /dev/null and b/src/debug/elf/testdata/go-relocation-test-gcc492-mipsle.obj differ

diff --git a/src/debug/elf/testdata/go-relocation-test-gcc540-mips.obj b/src/debug/elf/testdata/go-relocation-test-gcc540-mips.obj
new file mode 100644 (file)
index 0000000..270c777
Binary files /dev/null and b/src/debug/elf/testdata/go-relocation-test-gcc540-mips.obj differ