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cmd/link: fix loadelf failed on MIPS family

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The relocation of MIPS64 family ELF is different with other architecure according
to the document from Linux-MIPS

https://www.linux-mips.org/pub/linux/mips/doc/ABI/elf64-2.4.pdf

In "2.9 Relocation" it shows relocation section contains five parts:

1. r_sym Elf64_Word Symbol index
2. r_ssym Elf64_Byte Special symbol
3. r_type3 Elf64_Byte Relocation type
4. r_type2 Elf64_Byte Relocation type
5. r_type Elf64_Byte Relocation type

This CL makes loadelf aware the difference.

Update #35779

Change-Id: Ib221665641972b1c2bfea5a496e3118e5dc0bc45
Reviewed-on: https://go-review.googlesource.com/c/go/+/209317
Run-TryBot: Cherry Zhang <cherryyz@google.com>
Reviewed-by: Cherry Zhang <cherryyz@google.com>
This commit is contained in:
Meng Zhuo 2019-12-06 16:13:44 +08:00 committed by Cherry Zhang
parent a3a630b0d2
commit ffa5c85c92
2 changed files with 48 additions and 24 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

7
src/cmd/link/elf_test.go
View File

@ -15,7 +15,6 @@ import (
"os"
"os/exec"
"path/filepath"
"runtime"
"strings"
"sync"
"testing"
@ -143,12 +142,6 @@ func TestMinusRSymsWithSameName(t *testing.T) {
testenv.MustHaveCGO(t)
t.Parallel()
// Skip this test on MIPS for the time being since it seems to trigger
// problems with unknown relocations.
if strings.Contains(runtime.GOARCH, "mips") {
testenv.SkipFlaky(t, 35779)
}
dir, err := ioutil.TempDir("", "go-link-TestMinusRSymsWithSameName")
if err != nil {
t.Fatal(err)

65
src/cmd/link/internal/loadelf/ldelf.go
View File

@ -904,14 +904,26 @@ func load(arch *sys.Arch, localSymVersion int, newSym, lookup lookupFunc, f *bio
p := rsect.base
for j := 0; j < n; j++ {
var add uint64
var symIdx int
var relocType uint64
rp := &r[j]
var info uint64
if is64 != 0 {
// 64-bit rel/rela
rp.Off = int32(e.Uint64(p))
p = p[8:]
info = e.Uint64(p)
switch arch.Family {
case sys.MIPS64:
// https://www.linux-mips.org/pub/linux/mips/doc/ABI/elf64-2.4.pdf
// The doc shows it's different with general Linux ELF
symIdx = int(e.Uint32(p))
relocType = uint64(p[7])
default:
info := e.Uint64(p)
relocType = info & 0xffffffff
symIdx = int(info >> 32)
}
p = p[8:]
if rela != 0 {
add = e.Uint64(p)
@ -922,8 +934,9 @@ func load(arch *sys.Arch, localSymVersion int, newSym, lookup lookupFunc, f *bio
rp.Off = int32(e.Uint32(p))
p = p[4:]
info = uint64(e.Uint32(p))
info = info>>8<<32 | info&0xff // convert to 64-bit info
info := e.Uint32(p)
relocType = uint64(info & 0xff)
symIdx = int(info >> 8)
p = p[4:]
if rela != 0 {
add = uint64(e.Uint32(p))
@ -931,29 +944,29 @@ func load(arch *sys.Arch, localSymVersion int, newSym, lookup lookupFunc, f *bio
}
}
if info&0xffffffff == 0 { // skip R_*_NONE relocation
if relocType == 0 { // skip R_*_NONE relocation
j--
n--
continue
}
if info>>32 == 0 { // absolute relocation, don't bother reading the null symbol
if symIdx == 0 { // absolute relocation, don't bother reading the null symbol
rp.Sym = nil
} else {
var elfsym ElfSym
if err := readelfsym(newSym, lookup, arch, elfobj, int(info>>32), &elfsym, 0, 0); err != nil {
if err := readelfsym(newSym, lookup, arch, elfobj, symIdx, &elfsym, 0, 0); err != nil {
return errorf("malformed elf file: %v", err)
}
elfsym.sym = symbols[info>>32]
elfsym.sym = symbols[symIdx]
if elfsym.sym == nil {
return errorf("malformed elf file: %s#%d: reloc of invalid sym #%d %s shndx=%d type=%d", sect.sym.Name, j, int(info>>32), elfsym.name, elfsym.shndx, elfsym.type_)
return errorf("malformed elf file: %s#%d: reloc of invalid sym #%d %s shndx=%d type=%d", sect.sym.Name, j, symIdx, elfsym.name, elfsym.shndx, elfsym.type_)
}
rp.Sym = elfsym.sym
}
rp.Type = objabi.ElfRelocOffset + objabi.RelocType(info)
rp.Siz, err = relSize(arch, pn, uint32(info))
rp.Type = objabi.ElfRelocOffset + objabi.RelocType(relocType)
rp.Siz, err = relSize(arch, pn, uint32(relocType))
if err != nil {
return nil, 0, err
}
@ -1147,18 +1160,36 @@ func relSize(arch *sys.Arch, pn string, elftype uint32) (uint8, error) {
// performance.
const (
AMD64 = uint32(sys.AMD64)
ARM = uint32(sys.ARM)
ARM64 = uint32(sys.ARM64)
I386 = uint32(sys.I386)
PPC64 = uint32(sys.PPC64)
S390X = uint32(sys.S390X)
AMD64 = uint32(sys.AMD64)
ARM = uint32(sys.ARM)
ARM64 = uint32(sys.ARM64)
I386 = uint32(sys.I386)
PPC64 = uint32(sys.PPC64)
S390X = uint32(sys.S390X)
MIPS = uint32(sys.MIPS)
MIPS64 = uint32(sys.MIPS64)
)
switch uint32(arch.Family) | elftype<<16 {
default:
return 0, fmt.Errorf("%s: unknown relocation type %d; compiled without -fpic?", pn, elftype)
case MIPS | uint32(elf.R_MIPS_HI16)<<16,
MIPS | uint32(elf.R_MIPS_LO16)<<16,
MIPS | uint32(elf.R_MIPS_GOT16)<<16,
MIPS | uint32(elf.R_MIPS_GPREL16)<<16,
MIPS | uint32(elf.R_MIPS_GOT_PAGE)<<16,
MIPS | uint32(elf.R_MIPS_JALR)<<16,
MIPS | uint32(elf.R_MIPS_GOT_OFST)<<16,
MIPS64 | uint32(elf.R_MIPS_HI16)<<16,
MIPS64 | uint32(elf.R_MIPS_LO16)<<16,
MIPS64 | uint32(elf.R_MIPS_GOT16)<<16,
MIPS64 | uint32(elf.R_MIPS_GPREL16)<<16,
MIPS64 | uint32(elf.R_MIPS_GOT_PAGE)<<16,
MIPS64 | uint32(elf.R_MIPS_JALR)<<16,
MIPS64 | uint32(elf.R_MIPS_GOT_OFST)<<16:
return 4, nil
case S390X | uint32(elf.R_390_8)<<16:
return 1, nil