[dev.power64] debug/elf: add power64 support along with relocation test

LGTM=rsc
R=rsc, iant
CC=golang-codereviews
https://codereview.appspot.com/125910043

4 files changed, 233 insertions, 1 deletions

diff --git a/src/pkg/debug/elf/elf.go b/src/pkg/debug/elf/elf.go
index d622dae2a..51319c0dd 100644
--- a/src/pkg/debug/elf/elf.go
+++ b/src/pkg/debug/elf/elf.go
@@ -1162,6 +1162,184 @@ var rppcStrings = []intName{
 func (i R_PPC) String() string   { return stringName(uint32(i), rppcStrings, false) }
 func (i R_PPC) GoString() string { return stringName(uint32(i), rppcStrings, true) }
 
+// Relocation types for PowerPC 64.
+type R_PPC64 int
+
+const (
+	R_PPC64_NONE               R_PPC64 = 0
+	R_PPC64_ADDR32             R_PPC64 = 1
+	R_PPC64_ADDR24             R_PPC64 = 2
+	R_PPC64_ADDR16             R_PPC64 = 3
+	R_PPC64_ADDR16_LO          R_PPC64 = 4
+	R_PPC64_ADDR16_HI          R_PPC64 = 5
+	R_PPC64_ADDR16_HA          R_PPC64 = 6
+	R_PPC64_ADDR14             R_PPC64 = 7
+	R_PPC64_ADDR14_BRTAKEN     R_PPC64 = 8
+	R_PPC64_ADDR14_BRNTAKEN    R_PPC64 = 9
+	R_PPC64_REL24              R_PPC64 = 10
+	R_PPC64_REL14              R_PPC64 = 11
+	R_PPC64_REL14_BRTAKEN      R_PPC64 = 12
+	R_PPC64_REL14_BRNTAKEN     R_PPC64 = 13
+	R_PPC64_GOT16              R_PPC64 = 14
+	R_PPC64_GOT16_LO           R_PPC64 = 15
+	R_PPC64_GOT16_HI           R_PPC64 = 16
+	R_PPC64_GOT16_HA           R_PPC64 = 17
+	R_PPC64_JMP_SLOT           R_PPC64 = 21
+	R_PPC64_REL32              R_PPC64 = 26
+	R_PPC64_ADDR64             R_PPC64 = 38
+	R_PPC64_ADDR16_HIGHER      R_PPC64 = 39
+	R_PPC64_ADDR16_HIGHERA     R_PPC64 = 40
+	R_PPC64_ADDR16_HIGHEST     R_PPC64 = 41
+	R_PPC64_ADDR16_HIGHESTA    R_PPC64 = 42
+	R_PPC64_REL64              R_PPC64 = 44
+	R_PPC64_TOC16              R_PPC64 = 47
+	R_PPC64_TOC16_LO           R_PPC64 = 48
+	R_PPC64_TOC16_HI           R_PPC64 = 49
+	R_PPC64_TOC16_HA           R_PPC64 = 50
+	R_PPC64_TOC                R_PPC64 = 51
+	R_PPC64_ADDR16_DS          R_PPC64 = 56
+	R_PPC64_ADDR16_LO_DS       R_PPC64 = 57
+	R_PPC64_GOT16_DS           R_PPC64 = 58
+	R_PPC64_GOT16_LO_DS        R_PPC64 = 59
+	R_PPC64_TOC16_DS           R_PPC64 = 63
+	R_PPC64_TOC16_LO_DS        R_PPC64 = 64
+	R_PPC64_TLS                R_PPC64 = 67
+	R_PPC64_DTPMOD64           R_PPC64 = 68
+	R_PPC64_TPREL16            R_PPC64 = 69
+	R_PPC64_TPREL16_LO         R_PPC64 = 70
+	R_PPC64_TPREL16_HI         R_PPC64 = 71
+	R_PPC64_TPREL16_HA         R_PPC64 = 72
+	R_PPC64_TPREL64            R_PPC64 = 73
+	R_PPC64_DTPREL16           R_PPC64 = 74
+	R_PPC64_DTPREL16_LO        R_PPC64 = 75
+	R_PPC64_DTPREL16_HI        R_PPC64 = 76
+	R_PPC64_DTPREL16_HA        R_PPC64 = 77
+	R_PPC64_DTPREL64           R_PPC64 = 78
+	R_PPC64_GOT_TLSGD16        R_PPC64 = 79
+	R_PPC64_GOT_TLSGD16_LO     R_PPC64 = 80
+	R_PPC64_GOT_TLSGD16_HI     R_PPC64 = 81
+	R_PPC64_GOT_TLSGD16_HA     R_PPC64 = 82
+	R_PPC64_GOT_TLSLD16        R_PPC64 = 83
+	R_PPC64_GOT_TLSLD16_LO     R_PPC64 = 84
+	R_PPC64_GOT_TLSLD16_HI     R_PPC64 = 85
+	R_PPC64_GOT_TLSLD16_HA     R_PPC64 = 86
+	R_PPC64_GOT_TPREL16_DS     R_PPC64 = 87
+	R_PPC64_GOT_TPREL16_LO_DS  R_PPC64 = 88
+	R_PPC64_GOT_TPREL16_HI     R_PPC64 = 89
+	R_PPC64_GOT_TPREL16_HA     R_PPC64 = 90
+	R_PPC64_GOT_DTPREL16_DS    R_PPC64 = 91
+	R_PPC64_GOT_DTPREL16_LO_DS R_PPC64 = 92
+	R_PPC64_GOT_DTPREL16_HI    R_PPC64 = 93
+	R_PPC64_GOT_DTPREL16_HA    R_PPC64 = 94
+	R_PPC64_TPREL16_DS         R_PPC64 = 95
+	R_PPC64_TPREL16_LO_DS      R_PPC64 = 96
+	R_PPC64_TPREL16_HIGHER     R_PPC64 = 97
+	R_PPC64_TPREL16_HIGHERA    R_PPC64 = 98
+	R_PPC64_TPREL16_HIGHEST    R_PPC64 = 99
+	R_PPC64_TPREL16_HIGHESTA   R_PPC64 = 100
+	R_PPC64_DTPREL16_DS        R_PPC64 = 101
+	R_PPC64_DTPREL16_LO_DS     R_PPC64 = 102
+	R_PPC64_DTPREL16_HIGHER    R_PPC64 = 103
+	R_PPC64_DTPREL16_HIGHERA   R_PPC64 = 104
+	R_PPC64_DTPREL16_HIGHEST   R_PPC64 = 105
+	R_PPC64_DTPREL16_HIGHESTA  R_PPC64 = 106
+	R_PPC64_TLSGD              R_PPC64 = 107
+	R_PPC64_TLSLD              R_PPC64 = 108
+	R_PPC64_REL16              R_PPC64 = 249
+	R_PPC64_REL16_LO           R_PPC64 = 250
+	R_PPC64_REL16_HI           R_PPC64 = 251
+	R_PPC64_REL16_HA           R_PPC64 = 252
+)
+
+var rppc64Strings = []intName{
+	{0, "R_PPC64_NONE"},
+	{1, "R_PPC64_ADDR32"},
+	{2, "R_PPC64_ADDR24"},
+	{3, "R_PPC64_ADDR16"},
+	{4, "R_PPC64_ADDR16_LO"},
+	{5, "R_PPC64_ADDR16_HI"},
+	{6, "R_PPC64_ADDR16_HA"},
+	{7, "R_PPC64_ADDR14"},
+	{8, "R_PPC64_ADDR14_BRTAKEN"},
+	{9, "R_PPC64_ADDR14_BRNTAKEN"},
+	{10, "R_PPC64_REL24"},
+	{11, "R_PPC64_REL14"},
+	{12, "R_PPC64_REL14_BRTAKEN"},
+	{13, "R_PPC64_REL14_BRNTAKEN"},
+	{14, "R_PPC64_GOT16"},
+	{15, "R_PPC64_GOT16_LO"},
+	{16, "R_PPC64_GOT16_HI"},
+	{17, "R_PPC64_GOT16_HA"},
+	{21, "R_PPC64_JMP_SLOT"},
+	{26, "R_PPC64_REL32"},
+	{38, "R_PPC64_ADDR64"},
+	{39, "R_PPC64_ADDR16_HIGHER"},
+	{40, "R_PPC64_ADDR16_HIGHERA"},
+	{41, "R_PPC64_ADDR16_HIGHEST"},
+	{42, "R_PPC64_ADDR16_HIGHESTA"},
+	{44, "R_PPC64_REL64"},
+	{47, "R_PPC64_TOC16"},
+	{48, "R_PPC64_TOC16_LO"},
+	{49, "R_PPC64_TOC16_HI"},
+	{50, "R_PPC64_TOC16_HA"},
+	{51, "R_PPC64_TOC"},
+	{56, "R_PPC64_ADDR16_DS"},
+	{57, "R_PPC64_ADDR16_LO_DS"},
+	{58, "R_PPC64_GOT16_DS"},
+	{59, "R_PPC64_GOT16_LO_DS"},
+	{63, "R_PPC64_TOC16_DS"},
+	{64, "R_PPC64_TOC16_LO_DS"},
+	{67, "R_PPC64_TLS"},
+	{68, "R_PPC64_DTPMOD64"},
+	{69, "R_PPC64_TPREL16"},
+	{70, "R_PPC64_TPREL16_LO"},
+	{71, "R_PPC64_TPREL16_HI"},
+	{72, "R_PPC64_TPREL16_HA"},
+	{73, "R_PPC64_TPREL64"},
+	{74, "R_PPC64_DTPREL16"},
+	{75, "R_PPC64_DTPREL16_LO"},
+	{76, "R_PPC64_DTPREL16_HI"},
+	{77, "R_PPC64_DTPREL16_HA"},
+	{78, "R_PPC64_DTPREL64"},
+	{79, "R_PPC64_GOT_TLSGD16"},
+	{80, "R_PPC64_GOT_TLSGD16_LO"},
+	{81, "R_PPC64_GOT_TLSGD16_HI"},
+	{82, "R_PPC64_GOT_TLSGD16_HA"},
+	{83, "R_PPC64_GOT_TLSLD16"},
+	{84, "R_PPC64_GOT_TLSLD16_LO"},
+	{85, "R_PPC64_GOT_TLSLD16_HI"},
+	{86, "R_PPC64_GOT_TLSLD16_HA"},
+	{87, "R_PPC64_GOT_TPREL16_DS"},
+	{88, "R_PPC64_GOT_TPREL16_LO_DS"},
+	{89, "R_PPC64_GOT_TPREL16_HI"},
+	{90, "R_PPC64_GOT_TPREL16_HA"},
+	{91, "R_PPC64_GOT_DTPREL16_DS"},
+	{92, "R_PPC64_GOT_DTPREL16_LO_DS"},
+	{93, "R_PPC64_GOT_DTPREL16_HI"},
+	{94, "R_PPC64_GOT_DTPREL16_HA"},
+	{95, "R_PPC64_TPREL16_DS"},
+	{96, "R_PPC64_TPREL16_LO_DS"},
+	{97, "R_PPC64_TPREL16_HIGHER"},
+	{98, "R_PPC64_TPREL16_HIGHERA"},
+	{99, "R_PPC64_TPREL16_HIGHEST"},
+	{100, "R_PPC64_TPREL16_HIGHESTA"},
+	{101, "R_PPC64_DTPREL16_DS"},
+	{102, "R_PPC64_DTPREL16_LO_DS"},
+	{103, "R_PPC64_DTPREL16_HIGHER"},
+	{104, "R_PPC64_DTPREL16_HIGHERA"},
+	{105, "R_PPC64_DTPREL16_HIGHEST"},
+	{106, "R_PPC64_DTPREL16_HIGHESTA"},
+	{107, "R_PPC64_TLSGD"},
+	{108, "R_PPC64_TLSLD"},
+	{249, "R_PPC64_REL16"},
+	{250, "R_PPC64_REL16_LO"},
+	{251, "R_PPC64_REL16_HI"},
+	{252, "R_PPC64_REL16_HA"},
+}
+
+func (i R_PPC64) String() string   { return stringName(uint32(i), rppc64Strings, false) }
+func (i R_PPC64) GoString() string { return stringName(uint32(i), rppc64Strings, true) }
+
 // Relocation types for SPARC.
 type R_SPARC int
 
diff --git a/src/pkg/debug/elf/file.go b/src/pkg/debug/elf/file.go
index 7be9deaa5..5e1c47a04 100644
--- a/src/pkg/debug/elf/file.go
+++ b/src/pkg/debug/elf/file.go
@@ -529,6 +529,9 @@ func (f *File) applyRelocations(dst []byte, rels []byte) error {
 	if f.Class == ELFCLASS32 && f.Machine == EM_386 {
 		return f.applyRelocations386(dst, rels)
 	}
+	if f.Class == ELFCLASS64 && f.Machine == EM_PPC64 {
+		return f.applyRelocationsPPC64(dst, rels)
+	}
 
 	return errors.New("not implemented")
 }
@@ -615,6 +618,51 @@ func (f *File) applyRelocations386(dst []byte, rels []byte) error {
 	return nil
 }
 
+func (f *File) applyRelocationsPPC64(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)
+		symNo := rela.Info >> 32
+		t := R_PPC64(rela.Info & 0xffff)
+
+		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_PPC64_ADDR64:
+			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_PPC64_ADDR32:
+			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) {
 	// There are many other DWARF sections, but these
 	// are the required ones, and the debug/dwarf package
@@ -637,7 +685,7 @@ func (f *File) DWARF() (*dwarf.Data, error) {
 	// If there's a relocation table for .debug_info, we have to process it
 	// now otherwise the data in .debug_info is invalid for x86-64 objects.
 	rela := f.Section(".rela.debug_info")
-	if rela != nil && rela.Type == SHT_RELA && f.Machine == EM_X86_64 {
+	if rela != nil && rela.Type == SHT_RELA && (f.Machine == EM_X86_64 || f.Machine == EM_PPC64) {
 		data, err := rela.Data()
 		if err != nil {
 			return nil, err
diff --git a/src/pkg/debug/elf/file_test.go b/src/pkg/debug/elf/file_test.go
index 5e4ad5c10..db9a7476c 100644
--- a/src/pkg/debug/elf/file_test.go
+++ b/src/pkg/debug/elf/file_test.go
@@ -261,6 +261,12 @@ var relocationTests = []relocationTest{
 		},
 	},
 	{
+		"testdata/go-relocation-test-gcc482-ppc64le.obj",
+		[]relocationTestEntry{
+			{0, &dwarf.Entry{Offset: 0xb, Tag: dwarf.TagCompileUnit, Children: true, Field: []dwarf.Field{dwarf.Field{Attr: dwarf.AttrProducer, Val: "GNU C 4.8.2 -Asystem=linux -Asystem=unix -Asystem=posix -msecure-plt -mtune=power8 -mcpu=power7 -gdwarf-2 -fstack-protector"}, dwarf.Field{Attr: dwarf.AttrLanguage, Val: int64(1)}, dwarf.Field{Attr: dwarf.AttrName, Val: "go-relocation-test-gcc482-ppc64le.c"}, dwarf.Field{Attr: dwarf.AttrCompDir, Val: "/tmp"}, dwarf.Field{Attr: dwarf.AttrLowpc, Val: uint64(0x0)}, dwarf.Field{Attr: dwarf.AttrHighpc, Val: uint64(0x24)}, dwarf.Field{Attr: dwarf.AttrStmtList, Val: int64(0)}}}},
+		},
+	},
+	{
 		"testdata/go-relocation-test-clang-x86.obj",
 		[]relocationTestEntry{
 			{0, &dwarf.Entry{Offset: 0xb, Tag: dwarf.TagCompileUnit, Children: true, Field: []dwarf.Field{{Attr: dwarf.AttrProducer, Val: "clang version google3-trunk (trunk r209387)"}, {Attr: dwarf.AttrLanguage, Val: int64(12)}, {Attr: dwarf.AttrName, Val: "go-relocation-test-clang.c"}, {Attr: dwarf.AttrStmtList, Val: int64(0)}, {Attr: dwarf.AttrCompDir, Val: "/tmp"}}}},
diff --git a/src/pkg/debug/elf/testdata/go-relocation-test-gcc482-ppc64le.obj b/src/pkg/debug/elf/testdata/go-relocation-test-gcc482-ppc64le.obj
new file mode 100644
index 000000000..dad744548
--- /dev/null
+++ b/src/pkg/debug/elf/testdata/go-relocation-test-gcc482-ppc64le.obj