cmd/internal/ld: support for -buildmode=shared
Change-Id: Id4997d611ced29397133f14def6abc88aa9e811e
Reviewed-on: https://go-review.googlesource.com/8252
Run-TryBot: Ian Lance Taylor <iant@golang.org>
Reviewed-by: Ian Lance Taylor <iant@golang.org>
diff --git a/src/cmd/6l/asm.go b/src/cmd/6l/asm.go
index c55dae4..07bb7c4 100644
--- a/src/cmd/6l/asm.go
+++ b/src/cmd/6l/asm.go
@@ -313,7 +313,11 @@
case ld.R_CALL:
if r.Siz == 4 {
if r.Xsym.Type == ld.SDYNIMPORT {
- ld.Thearch.Vput(ld.R_X86_64_GOTPCREL | uint64(elfsym)<<32)
+ if ld.DynlinkingGo() {
+ ld.Thearch.Vput(ld.R_X86_64_PLT32 | uint64(elfsym)<<32)
+ } else {
+ ld.Thearch.Vput(ld.R_X86_64_GOTPCREL | uint64(elfsym)<<32)
+ }
} else {
ld.Thearch.Vput(ld.R_X86_64_PC32 | uint64(elfsym)<<32)
}
diff --git a/src/cmd/6l/obj.go b/src/cmd/6l/obj.go
index ad1cf92..a1e012b 100644
--- a/src/cmd/6l/obj.go
+++ b/src/cmd/6l/obj.go
@@ -91,7 +91,7 @@
ld.Linkmode = ld.LinkInternal
}
- if ld.Buildmode == ld.BuildmodeCShared {
+ if ld.Buildmode == ld.BuildmodeCShared || ld.DynlinkingGo() {
ld.Linkmode = ld.LinkExternal
}
diff --git a/src/cmd/internal/ld/data.go b/src/cmd/internal/ld/data.go
index 76446b1..39dfea9 100644
--- a/src/cmd/internal/ld/data.go
+++ b/src/cmd/internal/ld/data.go
@@ -333,8 +333,14 @@
}
if r.Sym != nil && (r.Sym.Type&(SMASK|SHIDDEN) == 0 || r.Sym.Type&SMASK == SXREF) {
- Diag("%s: not defined", r.Sym.Name)
- continue
+ // When putting the runtime but not main into a shared library
+ // these symbols are undefined and that's OK.
+ if Buildmode == BuildmodeShared && (r.Sym.Name == "main.main" || r.Sym.Name == "main.init") {
+ r.Sym.Type = SDYNIMPORT
+ } else {
+ Diag("%s: not defined", r.Sym.Name)
+ continue
+ }
}
if r.Type >= 256 {
@@ -344,8 +350,9 @@
continue
}
- // Solaris needs the ability to reference dynimport symbols.
- if HEADTYPE != Hsolaris && r.Sym != nil && r.Sym.Type == SDYNIMPORT {
+ // We need to be able to reference dynimport symbols when linking against
+ // shared libraries, and Solaris needs it always
+ if HEADTYPE != Hsolaris && r.Sym != nil && r.Sym.Type == SDYNIMPORT && !DynlinkingGo() {
Diag("unhandled relocation for %s (type %d rtype %d)", r.Sym.Name, r.Sym.Type, r.Type)
}
if r.Sym != nil && r.Sym.Type != STLSBSS && !r.Sym.Reachable {
@@ -1322,7 +1329,7 @@
sect.Length = uint64(datsize) - sect.Vaddr
/* shared library initializer */
- if Buildmode == BuildmodeCShared {
+ if Buildmode == BuildmodeCShared || DynlinkingGo() {
sect := addsection(&Segdata, ".init_array", 06)
sect.Align = maxalign(s, SINITARR)
datsize = Rnd(datsize, int64(sect.Align))
@@ -1728,10 +1735,12 @@
xdefine("runtime.etypelink", SRODATA, int64(typelink.Vaddr+typelink.Length))
sym := Linklookup(Ctxt, "runtime.gcdata", 0)
+ sym.Local = true
xdefine("runtime.egcdata", SRODATA, Symaddr(sym)+sym.Size)
Linklookup(Ctxt, "runtime.egcdata", 0).Sect = sym.Sect
sym = Linklookup(Ctxt, "runtime.gcbss", 0)
+ sym.Local = true
xdefine("runtime.egcbss", SRODATA, Symaddr(sym)+sym.Size)
Linklookup(Ctxt, "runtime.egcbss", 0).Sect = sym.Sect
diff --git a/src/cmd/internal/ld/elf.go b/src/cmd/internal/ld/elf.go
index 3448fe6..a7674da 100644
--- a/src/cmd/internal/ld/elf.go
+++ b/src/cmd/internal/ld/elf.go
@@ -1658,7 +1658,7 @@
Addstring(shstrtab, ".note.GNU-stack")
}
- if Buildmode == BuildmodeCShared {
+ if Buildmode == BuildmodeCShared || DynlinkingGo() {
Addstring(shstrtab, ".init_array")
switch Thearch.Thechar {
case '6', '7', '9':
diff --git a/src/cmd/internal/ld/go.go b/src/cmd/internal/ld/go.go
index fac72f7..55c9bb2 100644
--- a/src/cmd/internal/ld/go.go
+++ b/src/cmd/internal/ld/go.go
@@ -619,47 +619,58 @@
fmt.Fprintf(&Bso, "%5.2f deadcode\n", obj.Cputime())
}
- mark(Linklookup(Ctxt, INITENTRY, 0))
- for i := 0; i < len(markextra); i++ {
- mark(Linklookup(Ctxt, markextra[i], 0))
- }
-
- for i := 0; i < len(dynexp); i++ {
- mark(dynexp[i])
- }
-
- markflood()
-
- // keep each beginning with 'typelink.' if the symbol it points at is being kept.
- for s := Ctxt.Allsym; s != nil; s = s.Allsym {
- if strings.HasPrefix(s.Name, "go.typelink.") {
- s.Reachable = len(s.R) == 1 && s.R[0].Sym.Reachable
+ if Buildmode == BuildmodeShared {
+ // Mark all symbols as reachable when building a
+ // shared library.
+ for s := Ctxt.Allsym; s != nil; s = s.Allsym {
+ if s.Type != 0 {
+ mark(s)
+ }
}
- }
-
- // remove dead text but keep file information (z symbols).
- var last *LSym
-
- for s := Ctxt.Textp; s != nil; s = s.Next {
- if !s.Reachable {
- continue
- }
-
- // NOTE: Removing s from old textp and adding to new, shorter textp.
- if last == nil {
- Ctxt.Textp = s
- } else {
- last.Next = s
- }
- last = s
- }
-
- if last == nil {
- Ctxt.Textp = nil
- Ctxt.Etextp = nil
+ mark(Linkrlookup(Ctxt, "main.main", 0))
+ mark(Linkrlookup(Ctxt, "main.init", 0))
} else {
- last.Next = nil
- Ctxt.Etextp = last
+ mark(Linklookup(Ctxt, INITENTRY, 0))
+ for i := 0; i < len(markextra); i++ {
+ mark(Linklookup(Ctxt, markextra[i], 0))
+ }
+
+ for i := 0; i < len(dynexp); i++ {
+ mark(dynexp[i])
+ }
+ markflood()
+
+ // keep each beginning with 'typelink.' if the symbol it points at is being kept.
+ for s := Ctxt.Allsym; s != nil; s = s.Allsym {
+ if strings.HasPrefix(s.Name, "go.typelink.") {
+ s.Reachable = len(s.R) == 1 && s.R[0].Sym.Reachable
+ }
+ }
+
+ // remove dead text but keep file information (z symbols).
+ var last *LSym
+
+ for s := Ctxt.Textp; s != nil; s = s.Next {
+ if !s.Reachable {
+ continue
+ }
+
+ // NOTE: Removing s from old textp and adding to new, shorter textp.
+ if last == nil {
+ Ctxt.Textp = s
+ } else {
+ last.Next = s
+ }
+ last = s
+ }
+
+ if last == nil {
+ Ctxt.Textp = nil
+ Ctxt.Etextp = nil
+ } else {
+ last.Next = nil
+ Ctxt.Etextp = last
+ }
}
for s := Ctxt.Allsym; s != nil; s = s.Allsym {
diff --git a/src/cmd/internal/ld/lib.go b/src/cmd/internal/ld/lib.go
index 2829b5b..ed54ce8 100644
--- a/src/cmd/internal/ld/lib.go
+++ b/src/cmd/internal/ld/lib.go
@@ -150,6 +150,14 @@
Rellen uint64
}
+// DynlinkingGo returns whether we are producing Go code that can live
+// in separate shared libraries linked together at runtime.
+func DynlinkingGo() bool {
+ // TODO(mwhudson): This is a bit silly for now, but it will need to have
+ // "|| Linkshared" appended when a subsequent change adds that flag.
+ return Buildmode == BuildmodeShared
+}
+
var (
Thestring string
Thelinkarch *LinkArch
@@ -241,11 +249,15 @@
// "c-shared": build a main package, plus all packages that it imports, into a
// single C shared library. The only callable symbols will be those functions
// marked as exported.
+// "shared": combine all packages passed on the command line, and their
+// dependencies, into a single shared library that will be used when
+// building with the -linkshared option.
type BuildMode uint8
const (
BuildmodeExe BuildMode = iota
BuildmodeCShared
+ BuildmodeShared
)
func (mode *BuildMode) Set(s string) error {
@@ -260,6 +272,13 @@
return fmt.Errorf("not supported on %s", goarch)
}
*mode = BuildmodeCShared
+ case "shared":
+ goos := obj.Getgoos()
+ goarch := obj.Getgoarch()
+ if goos != "linux" || goarch != "amd64" {
+ return fmt.Errorf("not supported on %s/%s", goos, goarch)
+ }
+ *mode = BuildmodeShared
}
return nil
}
@@ -270,6 +289,8 @@
return "exe"
case BuildmodeCShared:
return "c-shared"
+ case BuildmodeShared:
+ return "shared"
}
return fmt.Sprintf("BuildMode(%d)", uint8(*mode))
}
@@ -321,12 +342,16 @@
INITENTRY = fmt.Sprintf("_rt0_%s_%s_lib", goarch, goos)
case BuildmodeExe:
INITENTRY = fmt.Sprintf("_rt0_%s_%s", goarch, goos)
+ case BuildmodeShared:
+ // No INITENTRY for -buildmode=shared
default:
Diag("unknown INITENTRY for buildmode %v", Buildmode)
}
}
- Linklookup(Ctxt, INITENTRY, 0).Type = SXREF
+ if !DynlinkingGo() {
+ Linklookup(Ctxt, INITENTRY, 0).Type = SXREF
+ }
}
func Errorexit() {
@@ -790,6 +815,16 @@
if Buildmode == BuildmodeCShared {
argv = append(argv, "-Wl,-Bsymbolic")
argv = append(argv, "-shared")
+ } else if Buildmode == BuildmodeShared {
+ // TODO(mwhudson): unless you do this, dynamic relocations fill
+ // out the findfunctab table and for some reason shared libraries
+ // and the executable both define a main function and putting the
+ // address of executable's main into the shared libraries
+ // findfunctab violates the assumptions of the runtime. TBH, I
+ // think we may well end up wanting to use -Bsymbolic here
+ // anyway.
+ argv = append(argv, "-Wl,-Bsymbolic-functions")
+ argv = append(argv, "-shared")
}
argv = append(argv, "-o")
@@ -1162,7 +1197,8 @@
// external function.
// should never be called directly.
// only diagnose the direct caller.
- if depth == 1 && s.Type != SXREF {
+ // TODO(mwhudson): actually think about this.
+ if depth == 1 && s.Type != SXREF && !DynlinkingGo() {
Diag("call to external function %s", s.Name)
}
return -1
@@ -1477,6 +1513,7 @@
s.Value = v
s.Reachable = true
s.Special = 1
+ s.Local = true
}
func datoff(addr int64) int64 {
diff --git a/src/cmd/internal/ld/link.go b/src/cmd/internal/ld/link.go
index 0a63567..47af2ae 100644
--- a/src/cmd/internal/ld/link.go
+++ b/src/cmd/internal/ld/link.go
@@ -74,6 +74,7 @@
Pcln *Pcln
P []byte
R []Reloc
+ Local bool
}
type Reloc struct {
diff --git a/src/cmd/internal/ld/objfile.go b/src/cmd/internal/ld/objfile.go
index 34176be..ec84673 100644
--- a/src/cmd/internal/ld/objfile.go
+++ b/src/cmd/internal/ld/objfile.go
@@ -327,12 +327,14 @@
x, _ := strconv.ParseUint(s.Name[5:], 16, 32)
i32 := int32(x)
s.Type = SRODATA
+ s.Local = true
Adduint32(ctxt, s, uint32(i32))
s.Reachable = false
} else if strings.HasPrefix(s.Name, "$f64.") || strings.HasPrefix(s.Name, "$i64.") {
x, _ := strconv.ParseUint(s.Name[5:], 16, 64)
i64 := int64(x)
s.Type = SRODATA
+ s.Local = true
Adduint64(ctxt, s, uint64(i64))
s.Reachable = false
}
diff --git a/src/cmd/internal/ld/pcln.go b/src/cmd/internal/ld/pcln.go
index 65ca0c3..042be01 100644
--- a/src/cmd/internal/ld/pcln.go
+++ b/src/cmd/internal/ld/pcln.go
@@ -380,6 +380,7 @@
t := Linklookup(Ctxt, "runtime.findfunctab", 0)
t.Type = SRODATA
t.Reachable = true
+ t.Local = true
// find min and max address
min := Ctxt.Textp.Value
diff --git a/src/cmd/internal/ld/pobj.go b/src/cmd/internal/ld/pobj.go
index 32a8908..539e3d3 100644
--- a/src/cmd/internal/ld/pobj.go
+++ b/src/cmd/internal/ld/pobj.go
@@ -152,7 +152,7 @@
}
}
- if flag.NArg() != 1 {
+ if Buildmode != BuildmodeShared && flag.NArg() != 1 {
usage()
}
@@ -181,7 +181,21 @@
}
Bflush(&Bso)
- addlibpath(Ctxt, "command line", "command line", flag.Arg(0), "main")
+ if Buildmode == BuildmodeShared {
+ for i := 0; i < flag.NArg(); i++ {
+ arg := flag.Arg(i)
+ parts := strings.SplitN(arg, "=", 2)
+ var pkgpath, file string
+ if len(parts) == 1 {
+ pkgpath, file = "main", arg
+ } else {
+ pkgpath, file = parts[0], parts[1]
+ }
+ addlibpath(Ctxt, "command line", "command line", file, pkgpath)
+ }
+ } else {
+ addlibpath(Ctxt, "command line", "command line", flag.Arg(0), "main")
+ }
loadlib()
if Thearch.Thechar == '5' {
diff --git a/src/cmd/internal/ld/symtab.go b/src/cmd/internal/ld/symtab.go
index af818ce..7bcc1c6 100644
--- a/src/cmd/internal/ld/symtab.go
+++ b/src/cmd/internal/ld/symtab.go
@@ -40,8 +40,13 @@
putelfstr("")
}
- // Rewrite · to . for ASCII-only tools like DTrace (sigh)
- s = strings.Replace(s, "·", ".", -1)
+ // When dynamically linking, we create LSym's by reading the names from
+ // the symbol tables of the shared libraries and so the names need to
+ // match exactly. Tools like DTrace will have to wait for now.
+ if !DynlinkingGo() {
+ // Rewrite · to . for ASCII-only tools like DTrace (sigh)
+ s = strings.Replace(s, "·", ".", -1)
+ }
n := len(s) + 1
for len(Elfstrdat)+n > cap(Elfstrdat) {
@@ -130,7 +135,7 @@
// maybe one day STB_WEAK.
bind := STB_GLOBAL
- if ver != 0 || (x.Type&SHIDDEN != 0) {
+ if ver != 0 || (x.Type&SHIDDEN != 0) || x.Local {
bind = STB_LOCAL
}
@@ -138,7 +143,8 @@
// to get the exported symbols put into the dynamic symbol table.
// To avoid filling the dynamic table with lots of unnecessary symbols,
// mark all Go symbols local (not global) in the final executable.
- if Linkmode == LinkExternal && x.Cgoexport&CgoExportStatic == 0 && elfshnum != SHN_UNDEF {
+ // But when we're dynamically linking, we need all those global symbols.
+ if !DynlinkingGo() && Linkmode == LinkExternal && x.Cgoexport&CgoExportStatic == 0 && elfshnum != SHN_UNDEF {
bind = STB_LOCAL
}
@@ -322,21 +328,26 @@
xdefine("runtime.egcbss", SRODATA, 0)
// pseudo-symbols to mark locations of type, string, and go string data.
- s = Linklookup(Ctxt, "type.*", 0)
+ var symtype *LSym
+ if !DynlinkingGo() {
+ s = Linklookup(Ctxt, "type.*", 0)
- s.Type = STYPE
- s.Size = 0
- s.Reachable = true
- symtype := s
+ s.Type = STYPE
+ s.Size = 0
+ s.Reachable = true
+ symtype = s
+ }
s = Linklookup(Ctxt, "go.string.*", 0)
s.Type = SGOSTRING
+ s.Local = true
s.Size = 0
s.Reachable = true
symgostring := s
s = Linklookup(Ctxt, "go.func.*", 0)
s.Type = SGOFUNC
+ s.Local = true
s.Size = 0
s.Reachable = true
symgofunc := s
@@ -344,6 +355,7 @@
symtypelink := Linklookup(Ctxt, "runtime.typelink", 0)
symt = Linklookup(Ctxt, "runtime.symtab", 0)
+ symt.Local = true
symt.Type = SSYMTAB
symt.Size = 0
symt.Reachable = true
@@ -358,7 +370,7 @@
if !s.Reachable || s.Special != 0 || s.Type != SRODATA {
continue
}
- if strings.HasPrefix(s.Name, "type.") {
+ if strings.HasPrefix(s.Name, "type.") && !DynlinkingGo() {
s.Type = STYPE
s.Hide = 1
s.Outer = symtype
@@ -400,6 +412,7 @@
moduledata.Type = SNOPTRDATA
moduledata.Size = 0 // truncate symbol back to 0 bytes to reinitialize
moduledata.Reachable = true
+ moduledata.Local = true
// The pclntab slice
Addaddr(Ctxt, moduledata, Linklookup(Ctxt, "runtime.pclntab", 0))
adduint(Ctxt, moduledata, uint64(Linklookup(Ctxt, "runtime.pclntab", 0).Size))
