debug/elf: added MIPS ELF relocations

Change-Id: I05352749a852095baae2f67fd71ffcf5f727538d
Reviewed-on: https://go-review.googlesource.com/14453
Reviewed-by: Minux Ma <minux@golang.org>

src/debug/elf/elf.go

@@ -1246,6 +1246,115 @@ var r386Strings = []intName{
 func (i R_386) String() string   { return stringName(uint32(i), r386Strings, false) }
 func (i R_386) GoString() string { return stringName(uint32(i), r386Strings, true) }
 
+// Relocation types for MIPS.
+type R_MIPS int
+
+const (
+	R_MIPS_NONE          R_MIPS = 0
+	R_MIPS_16            R_MIPS = 1
+	R_MIPS_32            R_MIPS = 2
+	R_MIPS_REL32         R_MIPS = 3
+	R_MIPS_26            R_MIPS = 4
+	R_MIPS_HI16          R_MIPS = 5  /* high 16 bits of symbol value */
+	R_MIPS_LO16          R_MIPS = 6  /* low 16 bits of symbol value */
+	R_MIPS_GPREL16       R_MIPS = 7  /* GP-relative reference  */
+	R_MIPS_LITERAL       R_MIPS = 8  /* Reference to literal section  */
+	R_MIPS_GOT16         R_MIPS = 9  /* Reference to global offset table */
+	R_MIPS_PC16          R_MIPS = 10 /* 16 bit PC relative reference */
+	R_MIPS_CALL16        R_MIPS = 11 /* 16 bit call thru glbl offset tbl */
+	R_MIPS_GPREL32       R_MIPS = 12
+	R_MIPS_SHIFT5        R_MIPS = 16
+	R_MIPS_SHIFT6        R_MIPS = 17
+	R_MIPS_64            R_MIPS = 18
+	R_MIPS_GOT_DISP      R_MIPS = 19
+	R_MIPS_GOT_PAGE      R_MIPS = 20
+	R_MIPS_GOT_OFST      R_MIPS = 21
+	R_MIPS_GOT_HI16      R_MIPS = 22
+	R_MIPS_GOT_LO16      R_MIPS = 23
+	R_MIPS_SUB           R_MIPS = 24
+	R_MIPS_INSERT_A      R_MIPS = 25
+	R_MIPS_INSERT_B      R_MIPS = 26
+	R_MIPS_DELETE        R_MIPS = 27
+	R_MIPS_HIGHER        R_MIPS = 28
+	R_MIPS_HIGHEST       R_MIPS = 29
+	R_MIPS_CALL_HI16     R_MIPS = 30
+	R_MIPS_CALL_LO16     R_MIPS = 31
+	R_MIPS_SCN_DISP      R_MIPS = 32
+	R_MIPS_REL16         R_MIPS = 33
+	R_MIPS_ADD_IMMEDIATE R_MIPS = 34
+	R_MIPS_PJUMP         R_MIPS = 35
+	R_MIPS_RELGOT        R_MIPS = 36
+	R_MIPS_JALR          R_MIPS = 37
+
+	R_MIPS_TLS_DTPMOD32    R_MIPS = 38 /* Module number 32 bit */
+	R_MIPS_TLS_DTPREL32    R_MIPS = 39 /* Module-relative offset 32 bit */
+	R_MIPS_TLS_DTPMOD64    R_MIPS = 40 /* Module number 64 bit */
+	R_MIPS_TLS_DTPREL64    R_MIPS = 41 /* Module-relative offset 64 bit */
+	R_MIPS_TLS_GD          R_MIPS = 42 /* 16 bit GOT offset for GD */
+	R_MIPS_TLS_LDM         R_MIPS = 43 /* 16 bit GOT offset for LDM */
+	R_MIPS_TLS_DTPREL_HI16 R_MIPS = 44 /* Module-relative offset, high 16 bits */
+	R_MIPS_TLS_DTPREL_LO16 R_MIPS = 45 /* Module-relative offset, low 16 bits */
+	R_MIPS_TLS_GOTTPREL    R_MIPS = 46 /* 16 bit GOT offset for IE */
+	R_MIPS_TLS_TPREL32     R_MIPS = 47 /* TP-relative offset, 32 bit */
+	R_MIPS_TLS_TPREL64     R_MIPS = 48 /* TP-relative offset, 64 bit */
+	R_MIPS_TLS_TPREL_HI16  R_MIPS = 49 /* TP-relative offset, high 16 bits */
+	R_MIPS_TLS_TPREL_LO16  R_MIPS = 50 /* TP-relative offset, low 16 bits */
+)
+
+var rmipsStrings = []intName{
+	{0, "R_MIPS_NONE"},
+	{1, "R_MIPS_16"},
+	{2, "R_MIPS_32"},
+	{3, "R_MIPS_REL32"},
+	{4, "R_MIPS_26"},
+	{5, "R_MIPS_HI16"},
+	{6, "R_MIPS_LO16"},
+	{7, "R_MIPS_GPREL16"},
+	{8, "R_MIPS_LITERAL"},
+	{9, "R_MIPS_GOT16"},
+	{10, "R_MIPS_PC16"},
+	{11, "R_MIPS_CALL16"},
+	{12, "R_MIPS_GPREL32"},
+	{16, "R_MIPS_SHIFT5"},
+	{17, "R_MIPS_SHIFT6"},
+	{18, "R_MIPS_64"},
+	{19, "R_MIPS_GOT_DISP"},
+	{20, "R_MIPS_GOT_PAGE"},
+	{21, "R_MIPS_GOT_OFST"},
+	{22, "R_MIPS_GOT_HI16"},
+	{23, "R_MIPS_GOT_LO16"},
+	{24, "R_MIPS_SUB"},
+	{25, "R_MIPS_INSERT_A"},
+	{26, "R_MIPS_INSERT_B"},
+	{27, "R_MIPS_DELETE"},
+	{28, "R_MIPS_HIGHER"},
+	{29, "R_MIPS_HIGHEST"},
+	{30, "R_MIPS_CALL_HI16"},
+	{31, "R_MIPS_CALL_LO16"},
+	{32, "R_MIPS_SCN_DISP"},
+	{33, "R_MIPS_REL16"},
+	{34, "R_MIPS_ADD_IMMEDIATE"},
+	{35, "R_MIPS_PJUMP"},
+	{36, "R_MIPS_RELGOT"},
+	{37, "R_MIPS_JALR"},
+	{38, "R_MIPS_TLS_DTPMOD32"},
+	{39, "R_MIPS_TLS_DTPREL32"},
+	{40, "R_MIPS_TLS_DTPMOD64"},
+	{41, "R_MIPS_TLS_DTPREL64"},
+	{42, "R_MIPS_TLS_GD"},
+	{43, "R_MIPS_TLS_LDM"},
+	{44, "R_MIPS_TLS_DTPREL_HI16"},
+	{45, "R_MIPS_TLS_DTPREL_LO16"},
+	{46, "R_MIPS_TLS_GOTTPREL"},
+	{47, "R_MIPS_TLS_TPREL32"},
+	{48, "R_MIPS_TLS_TPREL64"},
+	{49, "R_MIPS_TLS_TPREL_HI16"},
+	{50, "R_MIPS_TLS_TPREL_LO16"},
+}
+
+func (i R_MIPS) String() string   { return stringName(uint32(i), rmipsStrings, false) }
+func (i R_MIPS) GoString() string { return stringName(uint32(i), rmipsStrings, true) }
+
 // Relocation types for PowerPC.
 type R_PPC int
 

src/debug/elf/file.go

@@ -537,6 +537,8 @@ 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 == ELFCLASS64 && f.Machine == EM_MIPS:
+		return f.applyRelocationsMIPS64(dst, rels)
 	default:
 		return errors.New("applyRelocations: not implemented")
 	}
@@ -800,6 +802,58 @@ func (f *File) applyRelocationsPPC64(dst []byte, rels []byte) error {
 	return nil
 }
 
+func (f *File) applyRelocationsMIPS64(dst []byte, rels []byte) error {
+	// 24 is the size of Rela64.
+	if len(rels)%24 != 0 {
+		return errors.New("length of relocation section is not a multiple of 24")
+	}
+
+	symbols, _, err := f.getSymbols(SHT_SYMTAB)
+	if err != nil {
+		return err
+	}
+
+	b := bytes.NewReader(rels)
+	var rela Rela64
+
+	for b.Len() > 0 {
+		binary.Read(b, f.ByteOrder, &rela)
+		var symNo uint64
+		var t R_MIPS
+		if f.ByteOrder == binary.BigEndian {
+			symNo = rela.Info >> 32
+			t = R_MIPS(rela.Info & 0xff)
+		} else {
+			symNo = rela.Info & 0xffffffff
+			t = R_MIPS(rela.Info >> 56)
+		}
+
+		if symNo == 0 || symNo > uint64(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_MIPS_64:
+			if rela.Off+8 >= uint64(len(dst)) || rela.Addend < 0 {
+				continue
+			}
+			f.ByteOrder.PutUint64(dst[rela.Off:rela.Off+8], uint64(rela.Addend))
+		case R_MIPS_32:
+			if rela.Off+4 >= uint64(len(dst)) || rela.Addend < 0 {
+				continue
+			}
+			f.ByteOrder.PutUint32(dst[rela.Off:rela.Off+4], uint32(rela.Addend))
+		}
+	}
+
+	return nil
+}
+
 func (f *File) DWARF() (*dwarf.Data, error) {
 	// sectionData gets the data for s, checks its size, and
 	// applies any applicable relations.

src/debug/elf/file_test.go

@@ -394,6 +394,44 @@ var relocationTests = []relocationTest{
 			}},
 		},
 	},
+	{
+		"testdata/go-relocation-test-gcc492-mips64.obj",
+		[]relocationTestEntry{
+			{0, &dwarf.Entry{
+				Offset:   0xb,
+				Tag:      dwarf.TagCompileUnit,
+				Children: true,
+				Field: []dwarf.Field{
+					{Attr: dwarf.AttrProducer, Val: "GNU C 4.9.2 -meb -mabi=64 -march=mips3 -mtune=mips64 -mllsc -mno-shared -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(100), Class: dwarf.ClassConstant},
+					{Attr: dwarf.AttrStmtList, Val: int64(0), Class: dwarf.ClassLinePtr},
+				},
+			}},
+		},
+	},
+	{
+		"testdata/go-relocation-test-gcc493-mips64le.obj",
+		[]relocationTestEntry{
+			{0, &dwarf.Entry{
+				Offset:   0xb,
+				Tag:      dwarf.TagCompileUnit,
+				Children: true,
+				Field: []dwarf.Field{
+					{Attr: dwarf.AttrProducer, Val: "GNU C 4.9.3 -mel -mabi=64 -mllsc -mno-shared -g -fstack-protector-strong", 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(100), Class: dwarf.ClassConstant},
+					{Attr: dwarf.AttrStmtList, Val: int64(0), Class: dwarf.ClassLinePtr},
+				},
+			}},
+		},
+	},
 	{
 		"testdata/go-relocation-test-clang-x86.obj",
 		[]relocationTestEntry{