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[dev.link] cmd/link: use RO memory (when avail) in elf loader

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Recreation of CL 206139 in the new symbol hierarchy.

Change-Id: Ic20c5c1b5db8f7eadf4c6ee4638e3c1a4e10ef3a
Reviewed-on: https://go-review.googlesource.com/c/go/+/219317
Run-TryBot: Jeremy Faller <jeremy@golang.org>
TryBot-Result: Gobot Gobot <gobot@golang.org>
Reviewed-by: Cherry Zhang <cherryyz@google.com>
This commit is contained in:
Jeremy Faller 2020-02-13 10:38:33 -05:00
parent 860f12a2fc
commit 9d673bf1db
2 changed files with 18 additions and 16 deletions
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1
src/cmd/link/internal/amd64/asm.go
View File

@ -158,6 +158,7 @@ func adddynrel(ctxt *ld.Link, s *sym.Symbol, r *sym.Reloc) bool {
if targ.Type != sym.SDYNIMPORT { if targ.Type != sym.SDYNIMPORT {
// have symbol // have symbol
if r.Off >= 2 && s.P[r.Off-2] == 0x8b { if r.Off >= 2 && s.P[r.Off-2] == 0x8b {
makeWritable(s)
// turn MOVQ of GOT entry into LEAQ of symbol itself // turn MOVQ of GOT entry into LEAQ of symbol itself
s.P[r.Off-2] = 0x8d s.P[r.Off-2] = 0x8d

33
src/cmd/link/internal/loadelf/ldelf.go
View File

@ -270,19 +270,20 @@ type ElfSymBytes64 struct {
} }
type ElfSect struct { type ElfSect struct {
name string name string
nameoff uint32 nameoff uint32
type_ uint32 type_ uint32
flags uint64 flags uint64
addr uint64 addr uint64
off uint64 off uint64
size uint64 size uint64
link uint32 link uint32
info uint32 info uint32
align uint64 align uint64
entsize uint64 entsize uint64
base []byte base []byte
sym loader.Sym readOnlyMem bool // Is this section in readonly memory?
sym loader.Sym
} }
type ElfObj struct { type ElfObj struct {
@ -600,7 +601,6 @@ func Load(l *loader.Loader, arch *sys.Arch, localSymVersion int, f *bio.Reader,
sect := &elfobj.sect[i] sect := &elfobj.sect[i]
if is64 != 0 { if is64 != 0 {
var b ElfSectBytes64 var b ElfSectBytes64
if err := binary.Read(f, e, &b); err != nil { if err := binary.Read(f, e, &b); err != nil {
return errorf("malformed elf file: %v", err) return errorf("malformed elf file: %v", err)
} }
@ -750,6 +750,7 @@ func Load(l *loader.Loader, arch *sys.Arch, localSymVersion int, f *bio.Reader,
sb.SetSize(int64(sect.size)) sb.SetSize(int64(sect.size))
sb.SetAlign(int32(sect.align)) sb.SetAlign(int32(sect.align))
sb.SetReadOnly(sect.readOnlyMem)
sect.sym = sb.Sym() sect.sym = sb.Sym()
} }
@ -1016,9 +1017,9 @@ func elfmap(elfobj *ElfObj, sect *ElfSect) (err error) {
return err return err
} }
sect.base = make([]byte, sect.size)
elfobj.f.MustSeek(int64(uint64(elfobj.base)+sect.off), 0) elfobj.f.MustSeek(int64(uint64(elfobj.base)+sect.off), 0)
if _, err := io.ReadFull(elfobj.f, sect.base); err != nil { sect.base, sect.readOnlyMem, err = elfobj.f.Slice(uint64(sect.size))
if err != nil {
return fmt.Errorf("short read: %v", err) return fmt.Errorf("short read: %v", err)
} }