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[dev.link] cmd/link: support external linking in new reloc implementation

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Support external linking for the new reloc pass as well, and
enable it on AMD64 and 386.

Change-Id: Ia71aec3d7c14e9d661e0748d2e988f29f220d1e1
Reviewed-on: https://go-review.googlesource.com/c/go/+/230308
Run-TryBot: Cherry Zhang <cherryyz@google.com>
TryBot-Result: Gobot Gobot <gobot@golang.org>
Reviewed-by: Jeremy Faller <jeremy@golang.org>
Reviewed-by: Than McIntosh <thanm@google.com>
This commit is contained in:
Cherry Zhang 2020-04-26 01:42:55 -04:00
parent 9a3bf7d542
commit 095d2a4532
3 changed files with 247 additions and 171 deletions
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55
src/cmd/link/internal/loader/loader.go
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@ -49,6 +49,17 @@ type Reloc struct {
Sym Sym // global index of symbol the reloc addresses
}
// ExtReloc contains the payload for an external relocation.
type ExtReloc struct {
Off int32 // offset to rewrite
Siz uint8 // number of bytes to rewrite: 0, 1, 2, or 4
Type objabi.RelocType // the relocation type
Sym Sym // global index of symbol the reloc addresses
Add int64 // addend
Xsym Sym
Xadd int64
}
// Reloc2 holds a "handle" to access a relocation record from an
// object file.
type Reloc2 struct {
@ -216,7 +227,8 @@ type Loader struct {
sects []*sym.Section // sections
symSects []uint16 // symbol's section, index to sects array
outdata [][]byte // symbol's data in the output buffer
outdata [][]byte // symbol's data in the output buffer
extRelocs [][]ExtReloc // symbol's external relocations
itablink map[Sym]struct{} // itablink[j] defined if j is go.itablink.*
@ -1108,6 +1120,16 @@ func (l *Loader) InitOutData() {
l.outdata = make([][]byte, l.extStart)
}
// SetExtRelocs sets the section of the i-th symbol. i is global index.
func (l *Loader) SetExtRelocs(i Sym, relocs []ExtReloc) {
l.extRelocs[i] = relocs
}
// InitExtRelocs initialize the slice used to store external relocations.
func (l *Loader) InitExtRelocs() {
l.extRelocs = make([][]ExtReloc, l.NSym())
}
// SymAlign returns the alignment for a symbol.
func (l *Loader) SymAlign(i Sym) int32 {
// If an alignment has been recorded, return that.
@ -2072,6 +2094,8 @@ func (l *Loader) LoadFull(arch *sys.Arch, syms *sym.Symbols, needReloc bool) {
l.convertRelocations(i, &relocs, s, false)
}
l.convertExtRelocs(s, i)
// Copy data
s.P = pp.data
@ -2632,6 +2656,8 @@ func loadObjFull(l *Loader, r *oReader, needReloc bool) {
l.convertRelocations(gi, &relocs, s, false)
}
l.convertExtRelocs(s, gi)
// Aux symbol info
auxs := r.Auxs(i)
for j := range auxs {
@ -2697,6 +2723,33 @@ func (l *Loader) convertRelocations(symIdx Sym, src *Relocs, dst *sym.Symbol, st
}
}
// Convert external relocations to sym.Relocs on symbol dst.
func (l *Loader) convertExtRelocs(dst *sym.Symbol, src Sym) {
if int(src) >= len(l.extRelocs) {
return
}
relocs := l.extRelocs[src]
if len(relocs) == 0 {
return
}
if len(dst.R) != 0 {
panic("bad")
}
dst.R = make([]sym.Reloc, len(relocs))
for i := range dst.R {
sr := &relocs[i]
r := &dst.R[i]
r.InitExt()
r.Off = sr.Off
r.Siz = sr.Siz
r.Type = sr.Type
r.Sym = l.Syms[sr.Sym]
r.Add = sr.Add
r.Xsym = l.Syms[sr.Xsym]
r.Xadd = sr.Xadd
}
}
// relocId is essentially a <S,R> tuple identifying the Rth
// relocation of symbol S.
type relocId struct {