8c, 8l dynamic loading support.

better mach binaries.
cgo working on darwin+linux amd64+386.
eliminated context switches - pi is 30x faster.
add libcgo to build.

on snow leopard:
  - non-cgo binaries work; all tests pass.
  - cgo binaries work on amd64 but not 386.

R=r
DELTA=2031  (1316 added, 626 deleted, 89 changed)
OCL=35264
CL=35304

misc/cgo/gmp/Makefile

@@ -5,6 +5,9 @@
 include $(GOROOT)/src/Make.$(GOARCH)
 
 TARG=gmp
+
+# Can have plain GOFILES too, but this example doesn't.
+
 CGOFILES=\
 	gmp.go
 
@@ -15,15 +18,21 @@ CGO_LDFLAGS=-lgmp
 # alternate installation of the library:
 #	CGO_CFLAGS=-I/home/rsc/gmp32/include
 #	CGO_LDFLAGS+=-L/home/rsc/gmp32/lib
+# Note the += on the second line.
 
-# Can have plain GOFILES too, but this example doesn't.
+CLEANFILES+=pi fib
 
 include $(GOROOT)/src/Make.pkg
 
-# Simple test program
+# Simple test programs
+
+# Computes 1000 digits of pi; single-threaded.
+pi: install pi.go
+	$(GC) pi.go
+	$(LD) -o $@ pi.$O
 
-pidigits.$O: install pidigits.go
-	$(GC) pidigits.go
+# Computes 200 Fibonacci numbers; multi-threaded.
+fib: install fib.go
+	$(GC) fib.go
+	$(LD) -o $@ fib.$O
 
-pidigits: pidigits.$O
-	$(LD) -o $@ pidigits.$O

misc/cgo/gmp/fib.go

+// Copyright 2009 The Go Authors.  All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+// Compute Fibonacci numbers with two goroutines
+// that pass integers back and forth.  No actual
+// concurrency, just threads and synchronization
+// and foreign code on multiple pthreads.
+
+package main
+
+import (
+	big "gmp";
+	"runtime";
+)
+
+func fibber(c chan *big.Int, out chan string, n int64) {
+	// Keep the fibbers in dedicated operating system
+	// threads, so that this program tests coordination
+	// between pthreads and not just goroutines.
+	runtime.LockOSThread();
+
+	i := big.NewInt(n);
+	if n == 0 {
+		c <- i;
+	}
+	for {
+		j := <-c;
+		out <- j.String();
+		i.Add(i, j);
+		c <- i;
+	}
+}
+
+func main() {
+	c := make(chan *big.Int);
+	out := make(chan string);
+	go fibber(c, out, 0);
+	go fibber(c, out, 1);
+	for i := 0; i < 200; i++ {
+		println(<-out);
+	}
+}

misc/cgo/stdio/Makefile

+# Copyright 2009 The Go Authors.  All rights reserved.
+# Use of this source code is governed by a BSD-style
+# license that can be found in the LICENSE file.
+
+include $(GOROOT)/src/Make.$(GOARCH)
+
+TARG=stdio
+CGOFILES=\
+	file.go
+
+CLEANFILES+=hello fib chain
+
+include $(GOROOT)/src/Make.pkg
+
+%: install %.go
+	$(GC) $*.go
+	$(LD) -o $@ $*.$O

misc/cgo/stdio/fib.go

+// Copyright 2009 The Go Authors.  All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+// Compute Fibonacci numbers with two goroutines
+// that pass integers back and forth.  No actual
+// concurrency, just threads and synchronization
+// and foreign code on multiple pthreads.
+
+package main
+
+import (
+	"runtime";
+	"stdio";
+	"strconv";
+)
+
+func fibber(c, out chan int64, i int64) {
+	// Keep the fibbers in dedicated operating system
+	// threads, so that this program tests coordination
+	// between pthreads and not just goroutines.
+	runtime.LockOSThread();
+
+	if i == 0 {
+		c <- i;
+	}
+	for {
+		j := <-c;
+		stdio.Puts(strconv.Itoa64(j));
+		out <- j;
+		<-out;
+		i += j;
+		c <- i;
+	}
+}
+
+func main() {
+	c := make(chan int64);
+	out := make(chan int64);
+	go fibber(c, out, 0);
+	go fibber(c, out, 1);
+	<-out;
+	for i := 0; i < 90; i++ {
+		out <- 1;
+		<-out;
+	}
+}

misc/cgo/stdio/file.go

+// Copyright 2009 The Go Authors.  All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+/*
+A trivial example of wrapping a C library in Go.
+For a more complex example and explanation,
+see ../gmp/gmp.go.
+*/
+
+package stdio
+
+// TODO(rsc): Remove fflushstdout when C.fflush(C.stdout) works in cgo.
+
+/*
+#include <stdio.h>
+#include <stdlib.h>
+
+void fflushstdout(void) { fflush(stdout); }
+*/
+import "C"
+import "unsafe"
+
+/*
+type File C.FILE
+
+var Stdout = (*File)(C.stdout)
+var Stderr = (*File)(C.stderr)
+
+func (f *File) WriteString(s string) {
+	p := C.CString(s);
+	C.fputs(p, (*C.FILE)(f));
+	C.free(p);
+}
+*/
+
+func Puts(s string) {
+	p := C.CString(s);
+	C.puts(p);
+	C.free(unsafe.Pointer(p));
+	C.fflushstdout();
+}
+

misc/cgo/stdio/hello.go

+// Copyright 2009 The Go Authors.  All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+package main
+
+import "stdio"
+
+func main() {
+//	stdio.Stdout.WriteString("hello, world\n");
+	stdio.Puts("hello, world");
+}

src/Make.pkg

@@ -24,7 +24,7 @@ coverage:
 	6cov -g $(shell pwd) | grep -v '_test\.go:'
 
 clean:
-	rm -rf *.[$(OS)o] *.a [$(OS)].out *.cgo[12].go *.cgo[34].c *.so _obj _test _testmain.go
+	rm -rf *.[$(OS)o] *.a [$(OS)].out *.cgo[12].go *.cgo[34].c *.so _obj _test _testmain.go $(CLEANFILES)
 
 test:
 	gotest
@@ -81,7 +81,7 @@ dir:
 #	x.cgo4.c - C implementations compiled with gcc to create dynamic library
 #
 %.cgo1.go %.cgo2.go %.cgo3.c %.cgo4.c: %.go
-	cgo $*.go
+	cgo $(CGO_CFLAGS) $*.go
 
 # The rules above added x.cgo1.go and x.cgo2.go to $(GOFILES),
 # added x.cgo3.$O to $OFILES, and added the installed copy of
@@ -96,13 +96,16 @@ RUNTIME_CFLAGS=-I$(GOROOT)/src/pkg/runtime $(RUNTIME_CFLAGS_$(GOARCH))
 # Have to run gcc with the right size argument on hybrid 32/64 machines.
 _CGO_CFLAGS_386=-m32
 _CGO_CFLAGS_amd64=-m64
+_CGO_LDFLAGS_linux=-shared -lpthread -lm
+_CGO_LDFLAGS_darwin=-dynamiclib -Wl,-undefined,dynamic_lookup
+
 
 # Compile x.cgo4.c with gcc to make package_x.so.
 %.cgo4.o: %.cgo4.c
 	gcc $(_CGO_CFLAGS_$(GOARCH)) -fPIC -O2 -o $@ -c $(CGO_CFLAGS) $*.cgo4.c
 
 $(elem)_%.so: %.cgo4.o
-	gcc $(_CGO_CFLAGS_$(GOARCH)) -shared -o $@ $*.cgo4.o $(CGO_LDFLAGS)
+	gcc $(_CGO_CFLAGS_$(GOARCH)) $(_CGO_LDFLAGS_$(GOOS)) -o $@ $*.cgo4.o $(CGO_LDFLAGS)
 
 $(pkgdir)/$(dir)/$(elem)_%.so: $(elem)_%.so
 	@test -d $(GOROOT)/pkg && mkdir -p $(pkgdir)/$(dir)

src/cmd/6l/asm.c

@@ -425,16 +425,11 @@ asmb(void)
 	int32 v, magic;
 	int a, dynsym;
 	uchar *op1;
-	vlong vl, va, startva, fo, w, symo;
+	vlong vl, va, startva, fo, w, symo, machlink;
 	vlong symdatva = 0x99LL<<32;
 	ElfEhdr *eh;
 	ElfPhdr *ph, *pph;
 	ElfShdr *sh;
-	MachoHdr *mh;
-	MachoSect *msect;
-	MachoSeg *ms;
-	MachoDebug *md;
-	MachoLoad *ml;
 
 	if(debug['v'])
 		Bprint(&bso, "%5.2f asmb\n", cputime());
@@ -523,6 +518,10 @@ asmb(void)
 			datblk(v, datsize-v);
 	}
 
+	machlink = 0;
+	if(HEADTYPE == 6)
+		machlink = domacholink();
+
 	symsize = 0;
 	spsize = 0;
 	lcsize = 0;
@@ -539,7 +538,7 @@ asmb(void)
 			symo = HEADR+textsize+datsize;
 			break;
 		case 6:
-			symo = rnd(HEADR+textsize, INITRND)+rnd(datsize, INITRND);
+			symo = rnd(HEADR+textsize, INITRND)+rnd(datsize, INITRND)+machlink;
 			break;
 		case 7:
 			symo = rnd(HEADR+textsize, INITRND)+datsize;
@@ -607,92 +606,8 @@ asmb(void)
 		lputb(lcsize);			/* line offsets */
 		break;
 	case 6:
-		/* apple MACH */
-		va = HEADR;
-		mh = getMachoHdr();
-		mh->cpu = MACHO_CPU_AMD64;
-		mh->subcpu = MACHO_SUBCPU_X86;
-
-		/* segment for zero page */
-		ms = newMachoSeg("__PAGEZERO", 0);
-		ms->vsize = va;
-
-		/* text */
-		v = rnd(HEADR+textsize, INITRND);
-		ms = newMachoSeg("__TEXT", 1);
-		ms->vaddr = va;
-		ms->vsize = v;
-		ms->filesize = v;
-		ms->prot1 = 7;
-		ms->prot2 = 5;
-
-		msect = newMachoSect(ms, "__text");
-		msect->addr = va+HEADR;
-		msect->size = v - HEADR;
-		msect->off = HEADR;
-		msect->flag = 0x400;	/* flag - some instructions */
-
-		/* data */
-		w = datsize+bsssize;
-		ms = newMachoSeg("__DATA", 2);
-		ms->vaddr = va+v;
-		ms->vsize = w;
-		ms->fileoffset = v;
-		ms->filesize = datsize;
-		ms->prot1 = 7;
-		ms->prot2 = 3;
-
-		msect = newMachoSect(ms, "__data");
-		msect->addr = va+v;
-		msect->size = datsize;
-		msect->off = v;
-
-		msect = newMachoSect(ms, "__bss");
-		msect->addr = va+v+datsize;
-		msect->size = bsssize;
-		msect->flag = 1;	/* flag - zero fill */
-
-		ml = newMachoLoad(5, 42+2);	/* unix thread */
-		ml->data[0] = 4;	/* thread type */
-		ml->data[1] = 42;	/* word count */
-		ml->data[2+32] = entryvalue();	/* start pc */
-		ml->data[2+32+1] = entryvalue()>>32;
-
-		if(!debug['d']) {
-			ml = newMachoLoad(2, 4);	/* LC_SYMTAB */
-			USED(ml);
-
-			ml = newMachoLoad(11, 18);	/* LC_DYSYMTAB */
-			USED(ml);
-
-			ml = newMachoLoad(14, 6);	/* LC_LOAD_DYLINKER */
-			ml->data[0] = 12;	/* offset to string */
-			strcpy((char*)&ml->data[1], "/usr/lib/dyld");
-		}
-
-		if(!debug['s']) {
-			ms = newMachoSeg("__SYMDAT", 1);
-			ms->vaddr = symdatva;
-			ms->vsize = 8+symsize+lcsize;
-			ms->fileoffset = symo;
-			ms->filesize = 8+symsize+lcsize;
-			ms->prot1 = 7;
-			ms->prot2 = 5;
-
-			md = newMachoDebug();
-			md->fileoffset = symo+8;
-			md->filesize = symsize;
-
-			md = newMachoDebug();
-			md->fileoffset = symo+8+symsize;
-			md->filesize = lcsize;
-		}
-
-		a = machowrite();
-		if(a > MACHORESERVE)
-			diag("MACHORESERVE too small: %d > %d", a, MACHORESERVE);
+		asmbmacho(symdatva, symo);
 		break;
-
 	case 7:
 		/* elf amd-64 */
 
@@ -965,6 +880,8 @@ datblk(int32 s, int32 n)
 		curp = p;
 		if(!p->from.sym->reachable)
 			diag("unreachable symbol in datblk - %s", p->from.sym->name);
+		if(p->from.sym->type == SMACHO)
+			continue;
 		l = p->from.sym->value + p->from.offset - s;
 		c = p->from.scale;
 		i = 0;

src/cmd/6l/l.h

@@ -160,6 +160,8 @@ enum
 	SIMPORT,
 	SEXPORT,
 
+	SMACHO,
+
 	NHASH		= 10007,
 	NHUNK		= 100000,
 	MINSIZ		= 8,
@@ -362,6 +364,7 @@ EXTERN	Prog	undefp;
 EXTERN	vlong	textstksiz;
 EXTERN	vlong	textarg;
 extern	char	thechar;
+EXTERN	int	dynptrsize;
 
 #define	UP	(&undefp)
 
@@ -403,6 +406,7 @@ void	dobss(void);
 void	dodata(void);
 void	doelf(void);
 void	doinit(void);
+void	domacho(void);
 void	doprof1(void);
 void	doprof2(void);
 void	dostkoff(void);

src/cmd/6l/obj.c

@@ -191,12 +191,12 @@ main(int argc, char *argv[])
 	case 6:	/* apple MACH */
 		machoinit();
 		HEADR = MACHORESERVE;
+		if(INITRND == -1)
+			INITRND = 4096;
 		if(INITTEXT == -1)
 			INITTEXT = 4096+HEADR;
 		if(INITDAT == -1)
 			INITDAT = 0;
-		if(INITRND == -1)
-			INITRND = 4096;
 		break;
 	case 7:	/* elf64 executable */
 		elfinit();
@@ -393,6 +393,8 @@ main(int argc, char *argv[])
 	patch();
 	follow();
 	doelf();
+	if(HEADTYPE == 6)
+		domacho();
 	dodata();
 	dobss();
 	dostkoff();

src/cmd/6l/pass.c

@@ -142,6 +142,11 @@ dobss(void)
 	Sym *s;
 	int32 t;
 
+	if(dynptrsize > 0) {
+		/* dynamic pointer section between data and bss */
+		datsize = rnd(datsize, 8);
+	}
+
 	/* now the bss */
 	bsssize = 0;
 	for(i=0; i<NHASH; i++)
@@ -154,12 +159,13 @@ dobss(void)
 		s->size = t;
 		if(t >= 8)
 			bsssize = rnd(bsssize, 8);
-		s->value = bsssize + datsize;
+		s->value = bsssize + dynptrsize + datsize;
 		bsssize += t;
 	}
+
 	xdefine("data", SBSS, 0);
 	xdefine("edata", SBSS, datsize);
-	xdefine("end", SBSS, bsssize + datsize);
+	xdefine("end", SBSS, dynptrsize + bsssize + datsize);
 }
 
 Prog*

src/cmd/6l/span.c

@@ -237,6 +237,12 @@ asmsym(void)
 				putsymb(s->name, 'D', s->value+INITDAT, s->version, s->gotype);
 				continue;
 
+			case SMACHO:
+				if(!s->reachable)
+					continue;
+				putsymb(s->name, 'D', s->value+INITDAT+datsize+bsssize, s->version, s->gotype);
+				continue;
+
 			case SBSS:
 				if(!s->reachable)
 					continue;
@@ -715,6 +721,11 @@ vaddr(Adr *a)
 					v += INITTEXT;	/* TO DO */
 				v += s->value;
 				break;
+			case SMACHO:
+				if(!s->reachable)
+					sysfatal("unreachable symbol in vaddr - %s", s->name);
+				v += INITDAT + datsize + s->value;
+				break;
 			default:
 				if(!s->reachable)
 					diag("unreachable symbol in vaddr - %s", s->name);

src/cmd/8l/asm.c

@@ -257,7 +257,7 @@ needlib(char *name)
 	Sym *s;
 
 	/* reuse hash code in symbol table */
-	p = smprint(".elfload.%s", name);
+	p = smprint(".dynlib.%s", name);
 	s = lookup(p, 0);
 	if(s->type == 0) {
 		s->type = 100;	// avoid SDATA, etc.
@@ -414,8 +414,8 @@ asmb(void)
 {
 	Prog *p;
 	int32 v, magic;
-	int a, dynsym;
-	uint32 va, fo, w, symo, startva;
+	int a, i, dynsym;
+	uint32 va, fo, w, symo, startva, machlink;
 	uchar *op1;
 	ulong expectpc;
 	ElfEhdr *eh;
@@ -547,6 +547,10 @@ asmb(void)
 			datblk(v, datsize-v);
 	}
 
+	machlink = 0;
+	if(HEADTYPE == 6)
+		machlink = domacholink();
+
 	symsize = 0;
 	spsize = 0;
 	lcsize = 0;
@@ -572,7 +576,7 @@ asmb(void)
 			symo = HEADR+textsize+datsize;
 			break;
 		case 6:
-			symo = rnd(HEADR+textsize, INITRND)+rnd(datsize, INITRND);
+			symo = rnd(HEADR+textsize, INITRND)+rnd(datsize, INITRND)+machlink;
 			break;
 		case 7:
 		case 8:
@@ -740,89 +744,7 @@ asmb(void)
 		break;
 
 	case 6:
-		/* apple MACH */
-		va = HEADR;
-		mh = getMachoHdr();
-		mh->cpu = MACHO_CPU_386;
-		mh->subcpu = MACHO_SUBCPU_X86;
-
-		/* segment for zero page */
-		ms = newMachoSeg("__PAGEZERO", 0);
-		ms->vsize = va;
-
-		/* text */
-		v = rnd(HEADR+textsize, INITRND);
-		ms = newMachoSeg("__TEXT", 1);
-		ms->vaddr = va;
-		ms->vsize = v;
-		ms->filesize = v;
-		ms->prot1 = 7;
-		ms->prot2 = 5;
-
-		msect = newMachoSect(ms, "__text");
-		msect->addr = va+HEADR;
-		msect->size = v - HEADR;
-		msect->off = HEADR;
-		msect->flag = 0x400;	/* flag - some instructions */
-
-		/* data */
-		w = datsize+bsssize;
-		ms = newMachoSeg("__DATA", 2);
-		ms->vaddr = va+v;
-		ms->vsize = w;
-		ms->fileoffset = v;
-		ms->filesize = datsize;
-		ms->prot1 = 7;
-		ms->prot2 = 3;
-
-		msect = newMachoSect(ms, "__data");
-		msect->addr = va+v;
-		msect->size = datsize;
-		msect->off = v;
-
-		msect = newMachoSect(ms, "__bss");
-		msect->addr = va+v+datsize;
-		msect->size = bsssize;
-		msect->flag = 1;	/* flag - zero fill */
-
-		ml = newMachoLoad(5, 16+2);	/* unix thread */
-		ml->data[0] = 1;	/* thread type */
-		ml->data[1] = 16;	/* word count */
-		ml->data[2+10] = entryvalue();	/* start pc */
-
-		if(!debug['d']) {
-			ml = newMachoLoad(2, 4);	/* LC_SYMTAB */
-			USED(ml);
-
-			ml = newMachoLoad(11, 18);	/* LC_DYSYMTAB */
-			USED(ml);
-
-			ml = newMachoLoad(14, 6);	/* LC_LOAD_DYLINKER */
-			ml->data[0] = 12;	/* offset to string */
-			strcpy((char*)&ml->data[1], "/usr/lib/dyld");
-		}
-
-		if(!debug['s']) {
-			ms = newMachoSeg("__SYMDAT", 1);
-			ms->vaddr = symdatva;
-			ms->vsize = 8+symsize+lcsize;
-			ms->fileoffset = symo;
-			ms->filesize = 8+symsize+lcsize;
-			ms->prot1 = 7;
-			ms->prot2 = 5;
-
-			md = newMachoDebug();
-			md->fileoffset = symo+8;
-			md->filesize = symsize;
-
-			md = newMachoDebug();
-			md->fileoffset = symo+8+symsize;
-			md->filesize = lcsize;
-		}
-
-		a = machowrite();
-		if(a > MACHORESERVE)
-			diag("MACHORESERVE too small: %d > %d", a, MACHORESERVE);
+		asmbmacho(symdatva, symo);
 		break;
 
 	case 7:
@@ -963,6 +885,17 @@ asmb(void)
 			ph->type = PT_DYNAMIC;
 			ph->flags = PF_R + PF_W;
 			phsh(ph, sh);
+
+			/*
+			 * Thread-local storage segment (really just size).
+			 */
+			if(tlsoffset != 0) {
+				ph = newElfPhdr();
+				ph->type = PT_TLS;
+				ph->flags = PF_R;
+				ph->memsz = -tlsoffset;
+				ph->align = 4;
+			}
 		}
 
 		ph = newElfPhdr();
@@ -1105,6 +1038,8 @@ datblk(int32 s, int32 n)
 		curp = p;
 		if(!p->from.sym->reachable)
 			diag("unreachable symbol in datblk - %s", p->from.sym->name);
+		if(p->from.sym->type == SMACHO)
+			continue;
 		l = p->from.sym->value + p->from.offset - s;
 		c = p->from.scale;
 		i = 0;

src/cmd/8l/l.h

@@ -151,6 +151,8 @@ enum
 	SIMPORT,
 	SEXPORT,
 
+	SMACHO,	/* pointer to mach-o imported symbol */
+
 	NHASH		= 10007,
 	NHUNK		= 100000,
 	MINSIZ		= 4,
@@ -272,6 +274,7 @@ EXTERN	Prog*	curtext;
 EXTERN	Prog*	datap;
 EXTERN	Prog*	edatap;
 EXTERN	int32	datsize;
+EXTERN	int32	dynptrsize;
 EXTERN	char	debug[128];
 EXTERN	char	literal[32];
 EXTERN	Prog*	etextp;
@@ -311,6 +314,7 @@ EXTERN	int	version;
 EXTERN	Prog	zprg;
 EXTERN	int	dtype;
 EXTERN	char	thechar;
+EXTERN	int	tlsoffset;
 
 EXTERN	Adr*	reloca;
 EXTERN	int	doexp, dlm;

src/cmd/8l/obj.c

@@ -213,6 +213,11 @@ main(int argc, char *argv[])
 			Bprint(&bso, "HEADR = 0x%ld\n", HEADR);
 		break;
 	case 6:	/* apple MACH */
+		/*
+		 * OS X system constant - offset from %gs to our TLS.
+		 * Explained in ../../libcgo/darwin_386.c.
+		 */
+		tlsoffset = 0x468;
 		machoinit();
 		HEADR = MACHORESERVE;
 		if(INITTEXT == -1)
@@ -223,6 +228,13 @@ main(int argc, char *argv[])
 			INITRND = 4096;
 		break;
 	case 7:	/* elf32 executable */
+		/*
+		 * Linux ELF uses TLS offsets negative from %gs.
+		 * Translate 0(GS) and 4(GS) into -8(GS) and -4(GS).
+		 * Also known to ../../pkg/runtime/linux/386/sys.s
+		 * and ../../libcgo/linux_386.c.
+		 */
+		tlsoffset = -8;
 		elfinit();
 		HEADR = ELFRESERVE;
 		if(INITTEXT == -1)
@@ -373,6 +385,8 @@ main(int argc, char *argv[])
 	patch();
 	follow();
 	doelf();
+	if(HEADTYPE == 6)
+		domacho();
 	dodata();
 	dostkoff();
 	if(debug['p'])
@@ -592,11 +606,14 @@ zaddr(Biobuf *f, Adr *a, Sym *h[])
 		a->type = Bgetc(f);
 	if(t & T_GOTYPE)
 		a->gotype = h[Bgetc(f)];
+
+	t = a->type;
+	if(t == D_INDIR+D_GS)
+		a->offset += tlsoffset;
+
 	s = a->sym;
 	if(s == S)
 		return;
-
-	t = a->type;
 	if(t != D_AUTO && t != D_PARAM) {
 		if(a->gotype)
 			s->gotype = a->gotype;

src/cmd/8l/pass.c

@@ -125,6 +125,11 @@ dodata(void)
 		datsize += u;
 	}
 
+	if(dynptrsize > 0) {
+		/* dynamic pointer section between data and bss */
+		datsize = rnd(datsize, 4);
+	}
+
 	/* now the bss */
 	bsssize = 0;
 	for(i=0; i<NHASH; i++)
@@ -135,12 +140,13 @@ dodata(void)
 			continue;
 		t = s->value;
 		s->size = t;
-		s->value = bsssize + datsize;
+		s->value = bsssize + dynptrsize + datsize;
 		bsssize += t;
 	}
+
 	xdefine("data", SBSS, 0);
 	xdefine("edata", SBSS, datsize);
-	xdefine("end", SBSS, bsssize + datsize);
+	xdefine("end", SBSS, dynptrsize + bsssize + datsize);
 }
 
 Prog*
@@ -570,7 +576,7 @@ dostkoff(void)
 				p = appendp(p);	// load g into CX
 				p->as = AMOVL;
 				p->from.type = D_INDIR+D_GS;
-				p->from.offset = 0;
+				p->from.offset = tlsoffset + 0;
 				p->to.type = D_CX;
 
 				if(debug['K']) {

src/cmd/8l/span.c

@@ -219,6 +219,12 @@ asmsym(void)
 				putsymb(s->name, 'D', s->value+INITDAT, s->version, s->gotype);
 				continue;
 
+			case SMACHO:
+				if(!s->reachable)
+					continue;
+				putsymb(s->name, 'D', s->value+INITDAT+datsize+bsssize, s->version, s->gotype);
+				continue;
+
 			case SBSS:
 				if(!s->reachable)
 					continue;
@@ -611,6 +617,11 @@ vaddr(Adr *a)
 					sysfatal("unreachable symbol in vaddr - %s", s->name);
 				v += s->value;
 				break;
+			case SMACHO:
+				if(!s->reachable)
+					sysfatal("unreachable symbol in vaddr - %s", s->name);
+				v += INITDAT + datsize + s->value;
+				break;
 			default:
 				if(!s->reachable)
 					sysfatal("unreachable symbol in vaddr - %s", s->name);

src/cmd/cgo/ast.go

@@ -36,6 +36,7 @@ type Prog struct {
 	Vardef map[string]*Type;
 	Funcdef map[string]*FuncType;
 	PtrSize int64;
+	GccOptions []string;
 }
 
 // A Type collects information about a type in both the C and Go worlds.

src/cmd/cgo/gcc.go

@@ -172,6 +172,17 @@ func (p *Prog) loadDebugInfo() {
 	p.Typedef = conv.typedef;
 }
 
+func concat(a, b []string) []string {
+	c := make([]string, len(a)+len(b));
+	for i, s := range a {
+		c[i] = s;
+	}
+	for i, s := range b {
+		c[i+len(a)] = s;
+	}
+	return c;
+}
+
 // gccDebug runs gcc -gdwarf-2 over the C program stdin and
 // returns the corresponding DWARF data and any messages
 // printed to standard error.
@@ -182,7 +193,7 @@ func (p *Prog) gccDebug(stdin []byte) (*dwarf.Data, string) {
 	}
 
 	tmp := "_cgo_.o";
-	_, stderr, ok := run(stdin, []string{
+	base := []string{
 		"gcc",
 		machine,
 		"-Wall",	// many warnings
@@ -192,7 +203,8 @@ func (p *Prog) gccDebug(stdin []byte) (*dwarf.Data, string) {
 		"-c",	// do not link
 		"-xc", 	// input language is C
 		"-",	// read input from standard input
-	});
+	};
+	_, stderr, ok := run(stdin, concat(base, p.GccOptions));
 	if !ok {
 		return nil, string(stderr);
 	}

src/cmd/cgo/main.go

@@ -11,15 +11,13 @@
 package main
 
 import (
-	"flag";
 	"fmt";
 	"go/ast";
 	"os";
 )
 
 func usage() {
-	fmt.Fprint(os.Stderr, "usage: cgo file.cgo\n");
-	flag.PrintDefaults();
+	fmt.Fprint(os.Stderr, "usage: cgo [compiler options] file.go\n");
 }
 
 var ptrSizeMap = map[string]int64 {
@@ -28,9 +26,24 @@ var ptrSizeMap = map[string]int64 {
 	"arm": 4
 }
 
+var expandName = map[string]string {
+	"schar": "signed char",
+	"uchar": "unsigned char",
+	"ushort": "unsigned short",
+	"uint": "unsigned int",
+	"ulong": "unsigned long",
+	"longlong": "long long",
+	"ulonglong": "unsigned long long",
+}
+
 func main() {
-	flag.Usage = usage;
-	flag.Parse();
+	args := os.Args;
+	if len(args) < 2 {
+		usage();
+		os.Exit(2);
+	}
+	gccOptions := args[1:len(args)-1];
+	input := args[len(args)-1];
 
 	arch := os.Getenv("GOARCH");
 	if arch == "" {
@@ -41,14 +54,17 @@ func main() {
 		fatal("unknown architecture %s", arch);
 	}
 
-	args := flag.Args();
-	if len(args) != 1 {
-		usage();
-		os.Exit(2);
+	p := openProg(input);
+	for _, cref := range p.Crefs {
+		// Convert C.ulong to C.unsigned long, etc.
+		if expand, ok := expandName[cref.Name]; ok {
+			cref.Name = expand;
 		}
-	p := openProg(args[0]);
+	}
+
 	p.PtrSize = ptrSize;
 	p.Preamble = p.Preamble + "\n" + builtinProlog;
+	p.GccOptions = gccOptions;
 	p.loadDebugInfo();
 	p.Vardef = make(map[string]*Type);
 	p.Funcdef = make(map[string]*FuncType);
@@ -83,5 +99,5 @@ func main() {
 	}
 
 	p.PackagePath = p.Package;
-	p.writeOutput(args[0]);
+	p.writeOutput(input);
 }

src/cmd/cgo/out.go

@@ -198,7 +198,7 @@ const cProlog = `
 #include "cgocall.h"
 
 #pragma dynld initcgo initcgo "%s/libcgo.so"
-#pragma dynld cgo cgo "%s/libcgo.so"
+#pragma dynld libcgo_thread_start libcgo_thread_start "%s/libcgo.so"
 #pragma dynld _cgo_malloc _cgo_malloc "%s/libcgo.so"
 #pragma dynld _cgo_free free "%s/libcgo.so"
 

src/cmd/ld/macho.c

@@ -92,6 +92,22 @@ newMachoDebug(void)
 	return &xdebug[ndebug++];
 }
 
+
+// Generic linking code.
+
+static uchar *linkdata;
+static uint32 nlinkdata;
+static uint32 mlinkdata;
+
+static uchar *strtab;
+static uint32 nstrtab;
+static uint32 mstrtab;
+
+static char **dylib;
+static int ndylib;
+
+static vlong linkoff;
+
 int
 machowrite(void)
 {
@@ -205,3 +221,308 @@ machowrite(void)
 
 	return Boffset(&bso) - o1;
 }
+
+static void*
+grow(uchar **dat, uint32 *ndat, uint32 *mdat, uint32 n)
+{
+	uchar *p;
+	uint32 old;
+
+	if(*ndat+n > *mdat) {
+		old = *mdat;
+		*mdat = (*ndat+n)*2 + 128;
+		*dat = realloc(*dat, *mdat);
+		if(*dat == 0) {
+			diag("out of memory");
+			errorexit();
+		}
+		memset(*dat+old, 0, *mdat-old);
+	}
+	p = *dat + *ndat;
+	*ndat += n;
+	return p;
+}
+
+static int
+needlib(char *name)
+{
+	char *p;
+	Sym *s;
+
+	/* reuse hash code in symbol table */
+	p = smprint(".machoload.%s", name);
+	s = lookup(p, 0);
+	if(s->type == 0) {
+		s->type = 100;	// avoid SDATA, etc.
+		return 1;
+	}
+	return 0;
+}
+
+void
+domacho(void)
+{
+	int h, nsym, ptrsize;
+	char *p;
+	uchar *dat;
+	uint32 x;
+	Sym *s;
+
+	ptrsize = 4;
+	if(macho64)
+		ptrsize = 8;
+
+	// empirically, string table must begin with " \x00".
+	if(!debug['d'])
+		*(char*)grow(&strtab, &nstrtab, &mstrtab, 2) = ' ';
+
+	nsym = 0;
+	for(h=0; h<NHASH; h++) {
+		for(s=hash[h]; s!=S; s=s->link) {
+			if(!s->reachable || (s->type != SDATA && s->type != SBSS) || s->dynldname == nil)
+				continue;
+			if(debug['d']) {
+				diag("cannot use dynamic loading and -d");
+				errorexit();
+			}
+			s->type = SMACHO;
+			s->value = nsym*ptrsize;
+
+			/* symbol table entry - darwin still puts _ prefixes on all C symbols */
+			x = nstrtab;
+			p = grow(&strtab, &nstrtab, &mstrtab, 1+strlen(s->dynldname)+1);
+			*p++ = '_';
+			strcpy(p, s->dynldname);
+
+			dat = grow(&linkdata, &nlinkdata, &mlinkdata, 8+ptrsize);
+			dat[0] = x;
+			dat[1] = x>>8;
+			dat[2] = x>>16;
+			dat[3] = x>>24;
+			dat[4] = 0x01;	// type: N_EXT - external symbol
+
+			if(needlib(s->dynldlib)) {
+				if(ndylib%32 == 0) {
+					dylib = realloc(dylib, (ndylib+32)*sizeof dylib[0]);
+					if(dylib == nil) {
+						diag("out of memory");
+						errorexit();
+					}
+				}
+				dylib[ndylib++] = s->dynldlib;
+			}
+			nsym++;
+		}
+	}
+
+	/*
+	 * list of symbol table indexes.
+	 * we don't take advantage of the opportunity
+	 * to order the symbol table differently from
+	 * this list, so it is boring: 0 1 2 3 4 ...
+	 */
+	for(x=0; x<nsym; x++) {
+		dat = grow(&linkdata, &nlinkdata, &mlinkdata, 4);
+		dat[0] = x;
+		dat[1] = x>>8;
+		dat[2] = x>>16;
+		dat[3] = x>>24;
+	}
+
+	dynptrsize = nsym*ptrsize;
+}
+
+vlong
+domacholink(void)
+{
+	linkoff = 0;
+	if(nlinkdata > 0) {
+		linkoff = rnd(HEADR+textsize, INITRND) + rnd(datsize, INITRND);
+		seek(cout, linkoff, 0);
+		write(cout, linkdata, nlinkdata);
+		write(cout, strtab, nstrtab);
+	}
+	return rnd(nlinkdata+nstrtab, INITRND);
+}
+
+void
+asmbmacho(vlong symdatva, vlong symo)
+{
+	vlong v, w;
+	vlong va;
+	int a, i, ptrsize;
+	MachoHdr *mh;
+	MachoSect *msect;
+	MachoSeg *ms;
+	MachoDebug *md;
+	MachoLoad *ml;
+
+	/* apple MACH */
+	va = INITTEXT - HEADR;
+	mh = getMachoHdr();
+	switch(thechar){
+	default:
+		diag("unknown mach architecture");
+		errorexit();
+	case '6':
+		mh->cpu = MACHO_CPU_AMD64;
+		mh->subcpu = MACHO_SUBCPU_X86;
+		ptrsize = 8;
+		break;
+	case '8':
+		mh->cpu = MACHO_CPU_386;
+		mh->subcpu = MACHO_SUBCPU_X86;
+		ptrsize = 4;
+		break;
+	}
+
+	/* segment for zero page */
+	ms = newMachoSeg("__PAGEZERO", 0);
+	ms->vsize = va;
+
+	/* text */
+	v = rnd(HEADR+textsize, INITRND);
+	ms = newMachoSeg("__TEXT", 1);
+	ms->vaddr = va;
+	ms->vsize = v;
+	ms->filesize = v;
+	ms->prot1 = 7;
+	ms->prot2 = 5;
+
+	msect = newMachoSect(ms, "__text");
+	msect->addr = INITTEXT;
+	msect->size = textsize;
+	msect->off = INITTEXT - va;
+	msect->flag = 0x400;	/* flag - some instructions */
+
+	/* data */
+	w = datsize+dynptrsize+bsssize;
+	ms = newMachoSeg("__DATA", 2+(dynptrsize>0));
+	ms->vaddr = va+v;
+	ms->vsize = w;
+	ms->fileoffset = v;
+	ms->filesize = datsize;
+	ms->prot1 = 7;
+	ms->prot2 = 3;
+
+	msect = newMachoSect(ms, "__data");
+	msect->addr = va+v;
+	msect->size = datsize;
+	msect->off = v;
+
+	if(dynptrsize > 0) {
+		msect = newMachoSect(ms, "__nl_symbol_ptr");
+		msect->addr = va+v+datsize;
+		msect->size = dynptrsize;
+		msect->align = 2;
+		msect->flag = 6;	/* section with nonlazy symbol pointers */
+		/*
+		 * The reserved1 field is supposed to be the index of
+		 * the first entry in the list of symbol table indexes
+		 * in isymtab for the symbols we need.  We only use
+		 * pointers, so we need the entire list, so the index
+		 * here should be 0, which luckily is what the Mach-O
+		 * writing code emits by default for this not really reserved field.
+		msect->reserved1 = 0; - first indirect symbol table entry we need
+		 */
+	}
+
+	msect = newMachoSect(ms, "__bss");
+	msect->addr = va+v+datsize+dynptrsize;
+	msect->size = bsssize;
+	msect->flag = 1;	/* flag - zero fill */
+
+	switch(thechar) {
+	default:
+		diag("unknown macho architecture");
+		errorexit();
+	case '6':
+		ml = newMachoLoad(5, 42+2);	/* unix thread */
+		ml->data[0] = 4;	/* thread type */
+		ml->data[1] = 42;	/* word count */
+		ml->data[2+32] = entryvalue();	/* start pc */
+		ml->data[2+32+1] = entryvalue()>>32;
+		break;
+	case '8':
+		ml = newMachoLoad(5, 16+2);	/* unix thread */
+		ml->data[0] = 1;	/* thread type */
+		ml->data[1] = 16;	/* word count */
+		ml->data[2+10] = entryvalue();	/* start pc */
+		break;
+	}
+
+	if(!debug['d']) {
+		int nsym;
+
+		nsym = dynptrsize/ptrsize;
+
+		ms = newMachoSeg("__LINKEDIT", 0);
+		ms->vaddr = va+v+rnd(datsize+dynptrsize+bsssize, INITRND);
+		ms->vsize = nlinkdata+nstrtab;
+		ms->fileoffset = linkoff;
+		ms->filesize = nlinkdata+nstrtab;
+		ms->prot1 = 7;
+		ms->prot2 = 3;
+
+		ml = newMachoLoad(2, 4);	/* LC_SYMTAB */
+		ml->data[0] = linkoff;	/* symoff */
+		ml->data[1] = nsym;	/* nsyms */
+		ml->data[2] = linkoff + nlinkdata;	/* stroff */
+		ml->data[3] = nstrtab;	/* strsize */
+
+		ml = newMachoLoad(11, 18);	/* LC_DYSYMTAB */
+		ml->data[0] = 0;	/* ilocalsym */
+		ml->data[1] = 0;	/* nlocalsym */
+		ml->data[2] = 0;	/* iextdefsym */
+		ml->data[3] = 0;	/* nextdefsym */
+		ml->data[4] = 0;	/* iundefsym */
+		ml->data[5] = nsym;	/* nundefsym */
+		ml->data[6] = 0;	/* tocoffset */
+		ml->data[7] = 0;	/* ntoc */
+		ml->data[8] = 0;	/* modtaboff */
+		ml->data[9] = 0;	/* nmodtab */
+		ml->data[10] = 0;	/* extrefsymoff */
+		ml->data[11] = 0;	/* nextrefsyms */
+		ml->data[12] = linkoff + nlinkdata - nsym*4;	/* indirectsymoff */
+		ml->data[13] = nsym;	/* nindirectsyms */
+		ml->data[14] = 0;	/* extreloff */
+		ml->data[15] = 0;	/* nextrel */
+		ml->data[16] = 0;	/* locreloff */
+		ml->data[17] = 0;	/* nlocrel */
+
+		ml = newMachoLoad(14, 6);	/* LC_LOAD_DYLINKER */
+		ml->data[0] = 12;	/* offset to string */
+		strcpy((char*)&ml->data[1], "/usr/lib/dyld");
+
+		for(i=0; i<ndylib; i++) {
+			ml = newMachoLoad(12, 4+(strlen(dylib[i])+1+7)/8*2);	/* LC_LOAD_DYLIB */
+			ml->data[0] = 24;	/* offset of string from beginning of load */
+			ml->data[1] = 0;	/* time stamp */
+			ml->data[2] = 0;	/* version */
+			ml->data[3] = 0;	/* compatibility version */
+			strcpy((char*)&ml->data[4], dylib[i]);
+		}
+	}
+
+	if(!debug['s']) {
+		ms = newMachoSeg("__SYMDAT", 1);
+		ms->vaddr = symdatva;
+		ms->vsize = 8+symsize+lcsize;
+		ms->fileoffset = symo;
+		ms->filesize = 8+symsize+lcsize;
+		ms->prot1 = 7;
+		ms->prot2 = 5;
+
+		md = newMachoDebug();
+		md->fileoffset = symo+8;
+		md->filesize = symsize;
+
+		md = newMachoDebug();
+		md->fileoffset = symo+8+symsize;
+		md->filesize = lcsize;
+	}
+
+	a = machowrite();
+	if(a > MACHORESERVE)
+		diag("MACHORESERVE too small: %d > %d", a, MACHORESERVE);
+}

src/cmd/ld/macho.h

@@ -61,10 +61,17 @@ void	machoinit(void);
  * for Header, PHeaders, and SHeaders.
  * May waste some.
  */
-#define	MACHORESERVE	4096
+#define	MACHORESERVE	3*1024
 
 enum {
 	MACHO_CPU_AMD64 = (1<<24)|7,
 	MACHO_CPU_386 = 7,
 	MACHO_SUBCPU_X86 = 3,
+
+	MACHO32SYMSIZE = 12,
+	MACHO64SYMSIZE = 16,
 };
+
+void	domacho(void);
+vlong	domacholink(void);
+void	asmbmacho(vlong, vlong);

src/libcgo/386.S

+// Copyright 2009 The Go Authors.  All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+/*
+ * Apple still insists on underscore prefixes for C function names.
+ */
+#ifdef __APPLE__
+#define EXT(s) _##s
+#else
+#define EXT(s) s
+#endif
+
+/*
+ * void crosscall_386(void (*fn)(void))
+ *
+ * Calling into the 8c tool chain, where all registers are caller save.
+ * Called from standard x86 ABI, where %ebp, %ebx, %esi,
+ * and %edi are callee-save, so they must be saved explicitly.
+ */
+.globl EXT(crosscall_386)
+EXT(crosscall_386):
+	pushl %ebp
+	movl %esp, %ebp
+	pushl %ebx
+	pushl %esi
+	pushl %edi
+
+	movl 8(%ebp), %eax	/* fn */
+	call *%eax
+
+	popl %edi
+	popl %esi
+	popl %ebx
+	popl %ebp
+	ret
+

src/libcgo/Makefile

@@ -2,21 +2,29 @@
 # Use of this source code is governed by a BSD-style
 # license that can be found in the LICENSE file.
 
-# not linked into build for now
+all: libcgo.so
 
-CFLAGS_386=-m32
+install: $(GOROOT)/pkg/$(GOOS)_$(GOARCH)/libcgo.so
 
-TARG=libcgo.so
+OFILES=\
+	$(GOOS)_$(GOARCH).o\
+	$(GOARCH).o\
+	util.o\
 
-all: libcgo.so
+CFLAGS_386=-m32
+CFLAGS_amd64=-m64
 
-cgocall.o: cgocall.c
-	gcc $(CFLAGS_$(GOARCH)) -O2 -fPIC -o cgocall.o -c cgocall.c
+LDFLAGS_linux=-shared -lpthread -lm
+LDFLAGS_darwin=-dynamiclib -Wl,-undefined,dynamic_lookup /usr/lib/libpthread.dylib
 
-libcgo.so: cgocall.o
-	gcc $(CFLAGS_$(GOARCH)) -shared -o libcgo.so cgocall.o -lpthread -lm
+%.o: %.c
+	gcc $(CFLAGS_$(GOARCH)) -O2 -fPIC -o $@ -c $*.c
 
-install: $(GOROOT)/pkg/$(GOOS)_$(GOARCH)/libcgo.so
+%.o: %.S
+	gcc $(CFLAGS_$(GOARCH)) -O2 -fPIC -o $@ -c $*.S
+
+libcgo.so: $(OFILES)
+	gcc $(CFLAGS_$(GOARCH)) $(LDFLAGS_$(GOOS)) -o libcgo.so $(OFILES)
 
 $(GOROOT)/pkg/$(GOOS)_$(GOARCH)/libcgo.so: libcgo.so
 	cp libcgo.so $@

src/libcgo/amd64.S

+// Copyright 2009 The Go Authors.  All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+/*
+ * Apple still insists on underscore prefixes for C function names.
+ */
+#ifdef __APPLE__
+#define EXT(s) _##s
+#else
+#define EXT(s) s
+#endif
+
+/*
+ * void crosscall_amd64(M *m, G *g, void (*fn)(void))
+ *
+ * Calling into the 6c tool chain, where all registers are caller save.
+ * Called from standard x86-64 ABI, where %rbx, %rbp, %r12-%r15
+ * are callee-save so they must be saved explicitly.
+ * The standard x86-64 ABI passes the three arguments m, g, fn
+ * in %rdi, %rsi, %rdx.
+ *
+ * Also need to set %r15 to g and %r14 to m (see ../pkg/runtime/mkasmh.sh)
+ * during the call.
+ */
+.globl EXT(crosscall_amd64)
+EXT(crosscall_amd64):
+	pushq %rbx
+	pushq %rbp
+	pushq %r12
+	pushq %r13
+	pushq %r14
+	pushq %r15
+
+	movq %rdi, %r14	/* m */
+	movq %rsi, %r15	/* g */
+	call *%rdx	/* fn */
+
+	popq %r15
+	popq %r14
+	popq %r13
+	popq %r12
+	popq %rbp
+	popq %rbx
+	ret

src/libcgo/cgocall.c

-// Copyright 2009 The Go Authors.  All rights reserved.
-// Use of this source code is governed by a BSD-style
-// license that can be found in the LICENSE file.
-
-#define _GNU_SOURCE
-#include <stdio.h>
-#include <errno.h>
-#include <linux/futex.h>
-#include <sys/syscall.h>
-#include <sys/time.h>
-#include <pthread.h>
-#include <stdint.h>
-#include <string.h>
-#include <stdlib.h>
-
-#define nil ((void*)0)
-
-/*
- * gcc implementation of src/pkg/runtime/linux/thread.c
- */
-typedef struct Lock Lock;
-typedef struct Note Note;
-typedef uint32_t uint32;
-
-struct Lock
-{
-	uint32 key;
-	uint32 sema;	// ignored
-};
-
-struct Note
-{
-	Lock lock;
-	uint32 pad;
-};
-
-static struct timespec longtime =
-{
-	1<<30,	// 34 years
-	0
-};
-
-static int
-cas(uint32 *val, uint32 old, uint32 new)
-{
-	int ret;
-
-	__asm__ __volatile__(
-		"lock; cmpxchgl %2, 0(%3)\n"
-		"setz %%al\n"
-	:	"=a" (ret)
-	:	"a" (old),
-		"r" (new),
-		"r" (val)
-	:	"memory", "cc"
-	);
-
-	return ret & 1;
-}
-
-static void
-futexsleep(uint32 *addr, uint32 val)
-{
-	int ret;
-
-	ret = syscall(SYS_futex, (int*)addr, FUTEX_WAIT, val, &longtime, nil, 0);
-	if(ret >= 0 || errno == EAGAIN || errno == EINTR)
-		return;
-	fprintf(stderr, "futexsleep: %s\n", strerror(errno));
-	*(int*)0 = 0;
-}
-
-static void
-futexwakeup(uint32 *addr)
-{
-	int ret;
-
-	ret = syscall(SYS_futex, (int*)addr, FUTEX_WAKE, 1, nil, nil, 0);
-	if(ret >= 0)
-		return;
-	fprintf(stderr, "futexwakeup: %s\n", strerror(errno));
-	*(int*)0 = 0;
-}
-
-static void
-futexlock(Lock *l)
-{
-	uint32 v;
-
-again:
-	v = l->key;
-	if((v&1) == 0){
-		if(cas(&l->key, v, v|1)){
-			// Lock wasn't held; we grabbed it.
-			return;
-		}
-		goto again;
-	}
-
-	if(!cas(&l->key, v, v+2))
-		goto again;
-
-	futexsleep(&l->key, v+2);
-	for(;;){
-		v = l->key;
-		if((int)v < 2) {
-			fprintf(stderr, "futexsleep: invalid key %d\n", (int)v);
-			*(int*)0 = 0;
-		}
-		if(cas(&l->key, v, v-2))
-			break;
-	}
-	goto again;
-}
-
-static void
-futexunlock(Lock *l)
-{
-	uint32 v;
-
-again:
-	v = l->key;
-	if((v&1) == 0)
-		*(int*)0 = 0;
-	if(!cas(&l->key, v, v&~1))
-		goto again;
-
-	// If there were waiters, wake one.
-	if(v & ~1)
-		futexwakeup(&l->key);
-}
-
-static void
-lock(Lock *l)
-{
-	futexlock(l);
-}
-
-static void
-unlock(Lock *l)
-{
-	futexunlock(l);
-}
-
-void
-noteclear(Note *n)
-{
-	n->lock.key = 0;
-	futexlock(&n->lock);
-}
-
-static void
-notewakeup(Note *n)
-{
-	futexunlock(&n->lock);
-}
-
-static void
-notesleep(Note *n)
-{
-	futexlock(&n->lock);
-	futexunlock(&n->lock);
-}
-
-/*
- * runtime Cgo server.
- * gcc half of src/pkg/runtime/cgocall.c
- */
-
-typedef struct CgoWork CgoWork;
-typedef struct CgoServer CgoServer;
-typedef struct Cgo Cgo;
-
-struct Cgo
-{
-	Lock lock;
-	CgoServer *idle;
-	CgoWork *whead;
-	CgoWork *wtail;
-};
-
-struct CgoServer
-{
-	CgoServer *next;
-	Note note;
-	CgoWork *work;
-};
-
-struct CgoWork
-{
-	CgoWork *next;
-	Note note;
-	void (*fn)(void*);
-	void *arg;
-};
-
-Cgo cgo;
-
-static void newserver(void);
-
-void
-initcgo(void)
-{
-	newserver();
-}
-
-static void* go_pthread(void*);
-
-/*
- * allocate servers to handle any work that has piled up
- * and one more server to sit idle and wait for new work.
- */
-static void
-newserver(void)
-{
-	CgoServer *f;
-	CgoWork *w, *next;
-	pthread_t p;
-
-	lock(&cgo.lock);
-	// kick off new servers with work to do
-	for(w=cgo.whead; w; w=next) {
-		next = w;
-		w->next = nil;
-		f = malloc(sizeof *f);
-		memset(f, 0, sizeof *f);
-		f->work = w;
-		noteclear(&f->note);
-		notewakeup(&f->note);
-		if(pthread_create(&p, nil, go_pthread, f) < 0) {
-			fprintf(stderr, "pthread_create: %s\n", strerror(errno));
-			*(int*)0 = 0;
-		}
-	}
-	cgo.whead = nil;
-	cgo.wtail = nil;
-
-	// kick off one more server to sit idle
-	if(cgo.idle == nil) {
-		f = malloc(sizeof *f);
-		memset(f, 0, sizeof *f);
-		f->next = cgo.idle;
-		noteclear(&f->note);
-		cgo.idle = f;
-		if(pthread_create(&p, nil, go_pthread, f) < 0) {
-			fprintf(stderr, "pthread_create: %s\n", strerror(errno));
-			*(int*)0 = 0;
-		}
-	}
-	unlock(&cgo.lock);
-}
-
-static void*
-go_pthread(void *v)
-{
-	CgoServer *f;
-	CgoWork *w;
-
-	// newserver queued us; wait for work
-	f = v;
-	goto wait;
-
-	for(;;) {
-		// kick off new server to handle requests while we work
-		newserver();
-
-		// do work
-		w = f->work;
-		w->fn(w->arg);
-		notewakeup(&w->note);
-		f->work = nil;
-
-		// take some work if available
-		lock(&cgo.lock);
-		if((w = cgo.whead) != nil) {
-			cgo.whead = w->next;
-			if(cgo.whead == nil)
-				cgo.wtail = nil;
-			unlock(&cgo.lock);
-			f->work = w;
-			continue;
-		}
-
-		// otherwise queue
-		f->work = nil;
-		noteclear(&f->note);
-		f->next = cgo.idle;
-		cgo.idle = f;
-		unlock(&cgo.lock);
-
-wait:
-		// wait for work
-		notesleep(&f->note);
-	}
-}
-
-// Helper.
-
-void
-_cgo_malloc(void *p)
-{
-	struct a {
-		long long n;
-		void *ret;
-	} *a = p;
-
-	a->ret = malloc(a->n);
-}

src/libcgo/darwin_386.c

+// Copyright 2009 The Go Authors.  All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+#include <pthread.h>
+#include "libcgo.h"
+
+static void* threadentry(void*);
+static pthread_key_t k1, k2;
+
+/* gccism: arrange for inittls to be called at dynamic load time */
+static void inittls(void) __attribute__((constructor));
+
+static void
+inittls(void)
+{
+	uint32 x, y;
+	pthread_key_t tofree[16], k;
+	int i, ntofree;
+	int havek1, havek2;
+
+	/*
+	 * Allocate thread-local storage slots for m, g.
+	 * The key numbers start at 0x100, and we expect to be
+	 * one of the early calls to pthread_key_create, so we
+	 * should be able to get pretty low numbers.
+	 *
+	 * In Darwin/386 pthreads, %gs points at the thread
+	 * structure, and each key is an index into the thread-local
+	 * storage array that begins at offset 0x48 within in that structure.
+	 * It may happen that we are not quite the first function to try
+	 * to allocate thread-local storage keys, so instead of depending
+	 * on getting 0x100 and 0x101, we try for 0x108 and 0x109,
+	 * allocating keys until we get the ones we want and then freeing
+	 * the ones we didn't want.
+	 *
+	 * Thus the final offsets to use in %gs references are
+	 * 0x48+4*0x108 = 0x468 and 0x48+4*0x109 = 0x46c.
+	 *
+	 * The linker and runtime hard-code these constant offsets
+	 * from %gs where we expect to find m and g.  The code
+	 * below verifies that the constants are correct once it has
+	 * obtained the keys.  Known to ../cmd/8l/obj.c:/468
+	 * and to ../pkg/runtime/darwin/386/sys.s:/468
+	 *
+	 * This is truly disgusting and a bit fragile, but taking care
+	 * of it here protects the rest of the system from damage.
+	 * The alternative would be to use a global variable that
+	 * held the offset and refer to that variable each time we
+	 * need a %gs variable (m or g).  That approach would
+	 * require an extra instruction and memory reference in
+	 * every stack growth prolog and would also require
+	 * rewriting the code that 8c generates for extern registers.
+	 */
+	havek1 = 0;
+	havek2 = 0;
+	ntofree = 0;
+	while(!havek1 || !havek2) {
+		if(pthread_key_create(&k, nil) < 0) {
+			fprintf(stderr, "libcgo: pthread_key_create failed\n");
+			abort();
+		}
+		if(k == 0x108) {
+			havek1 = 1;
+			k1 = k;
+			continue;
+		}
+		if(k == 0x109) {
+			havek2 = 1;
+			k2 = k;
+			continue;
+		}
+		if(ntofree >= nelem(tofree)) {
+			fprintf(stderr, "libcgo: could not obtain pthread_keys\n");
+			fprintf(stderr, "\twanted 0x108 and 0x109\n");
+			fprintf(stderr, "\tgot");
+			for(i=0; i<ntofree; i++)
+				fprintf(stderr, " %#x", tofree[i]);
+			fprintf(stderr, "\n");
+			abort();
+		}
+		tofree[ntofree++] = k;
+	}
+
+	for(i=0; i<ntofree; i++)
+		pthread_key_delete(tofree[i]);
+
+	/*
+	 * We got the keys we wanted.  Make sure that we observe
+	 * updates to k1 at 0x468, to verify that the TLS array
+	 * offset from %gs hasn't changed.
+	 */
+	pthread_setspecific(k1, (void*)0x12345678);
+	asm volatile("movl %%gs:0x468, %0" : "=r"(x));
+
+	pthread_setspecific(k1, (void*)0x87654321);
+	asm volatile("movl %%gs:0x468, %0" : "=r"(y));
+
+	if(x != 0x12345678 || y != 0x87654321) {
+		printf("libcgo: thread-local storage %#x not at %%gs:0x468 - x=%#x y=%#x\n", k1, x, y);
+		abort();
+	}
+}
+
+void
+initcgo(void)
+{
+}
+
+void
+libcgo_sys_thread_start(ThreadStart *ts)
+{
+	pthread_attr_t attr;
+	pthread_t p;
+	size_t size;
+
+	pthread_attr_init(&attr);
+	pthread_attr_getstacksize(&attr, &size);
+	ts->g->stackguard = size;
+	pthread_create(&p, &attr, threadentry, ts);
+}
+
+static void*
+threadentry(void *v)
+{
+	ThreadStart ts;
+
+	ts = *(ThreadStart*)v;
+	free(v);
+
+	ts.g->stackbase = (uintptr)&ts;
+
+	/*
+	 * libcgo_sys_thread_start set stackguard to stack size;
+	 * change to actual guard pointer.
+	 */
+	ts.g->stackguard = (uintptr)&ts - ts.g->stackguard + 4096;
+
+	pthread_setspecific(k1, (void*)ts.g);
+	pthread_setspecific(k2, (void*)ts.m);
+
+	crosscall_386(ts.fn);
+	return nil;
+}

src/libcgo/darwin_amd64.c

+// Copyright 2009 The Go Authors.  All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+#include <pthread.h>
+#include "libcgo.h"
+
+static void* threadentry(void*);
+
+void
+initcgo(void)
+{
+}
+
+void
+libcgo_sys_thread_start(ThreadStart *ts)
+{
+	pthread_attr_t attr;
+	pthread_t p;
+	size_t size;
+
+	pthread_attr_init(&attr);
+	pthread_attr_getstacksize(&attr, &size);
+	ts->g->stackguard = size;
+	pthread_create(&p, &attr, threadentry, ts);
+}
+
+static void*
+threadentry(void *v)
+{
+	ThreadStart ts;
+
+	ts = *(ThreadStart*)v;
+	free(v);
+
+	ts.g->stackbase = (uintptr)&ts;
+
+	/*
+	 * libcgo_sys_thread_start set stackguard to stack size;
+	 * change to actual guard pointer.
+	 */
+	ts.g->stackguard = (uintptr)&ts - ts.g->stackguard + 4096;
+
+	crosscall_amd64(ts.m, ts.g, ts.fn);
+	return nil;
+}

src/libcgo/libcgo.h

+// Copyright 2009 The Go Authors.  All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+#include <stdint.h>
+#include <stdlib.h>
+#include <stdio.h>
+
+#define nil ((void*)0)
+#define nelem(x) (sizeof(x)/sizeof((x)[0]))
+
+typedef uint32_t uint32;
+typedef uintptr_t uintptr;
+
+/*
+ * The beginning of the per-goroutine structure,
+ * as defined in ../pkg/runtime/runtime.h.
+ * Just enough to edit these two fields.
+ */
+typedef struct G G;
+struct G
+{
+	uintptr stackguard;
+	uintptr stackbase;
+};
+
+/*
+ * Arguments to the libcgo_thread_start call.
+ * Also known to ../pkg/runtime/runtime.h.
+ */
+typedef struct ThreadStart ThreadStart;
+struct ThreadStart
+{
+	uintptr m;
+	G *g;
+	void (*fn)(void);
+};
+
+/*
+ * Called by 5c/6c/8c world.
+ * Makes a local copy of the ThreadStart and
+ * calls libcgo_sys_thread_start(ts).
+ */
+void libcgo_thread_start(ThreadStart *ts);
+
+/*
+ * Creates the new operating system thread (OS, arch dependent).
+ */
+void libcgo_sys_thread_start(ThreadStart *ts);
+
+/*
+ * Call fn in the 6c world, with m and g
+ * set to the given parameters.
+ */
+void crosscall_amd64(uintptr m, G *g, void (*fn)(void));
+
+/*
+ * Call fn in the 8c world.
+ */
+void crosscall_386(void (*fn)(void));

src/libcgo/linux_386.c

+// Copyright 2009 The Go Authors.  All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+#include <pthread.h>
+#include "libcgo.h"
+
+static void *threadentry(void*);
+
+void
+initcgo(void)
+{
+}
+
+void
+libcgo_sys_thread_start(ThreadStart *ts)
+{
+	pthread_attr_t attr;
+	pthread_t p;
+	size_t size;
+
+	pthread_attr_init(&attr);
+	pthread_attr_getstacksize(&attr, &size);
+	ts->g->stackguard = size;
+	pthread_create(&p, &attr, threadentry, ts);
+}
+
+static void*
+threadentry(void *v)
+{
+	ThreadStart ts;
+
+	ts = *(ThreadStart*)v;
+	free(v);
+
+	ts.g->stackbase = (uintptr)&ts;
+
+	/*
+	 * libcgo_sys_thread_start set stackguard to stack size;
+	 * change to actual guard pointer.
+	 */
+	ts.g->stackguard = (uintptr)&ts - ts.g->stackguard + 4096;
+
+	/*
+	 * Set specific keys.  On Linux/ELF, the thread local storage
+	 * is just before %gs:0.  Our dynamic 8.out's reserve 8 bytes
+	 * for the two words g and m at %gs:-8 and %gs:-4.
+	 */
+	asm volatile (
+		"movl %0, %%gs:-8\n"	// MOVL g, -8(GS)
+		"movl %1, %%gs:-4\n"	// MOVL m, -4(GS)
+		:: "r"(ts.g), "r"(ts.m)
+	);
+
+	crosscall_386(ts.fn);
+	return nil;
+}

src/libcgo/linux_amd64.c

+// Copyright 2009 The Go Authors.  All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+#include <pthread.h>
+#include "libcgo.h"
+
+static void* threadentry(void*);
+
+void
+initcgo(void)
+{
+}
+
+void
+libcgo_sys_thread_start(ThreadStart *ts)
+{
+	pthread_attr_t attr;
+	pthread_t p;
+	size_t size;
+
+	pthread_attr_init(&attr);
+	pthread_attr_getstacksize(&attr, &size);
+	ts->g->stackguard = size;
+	pthread_create(&p, &attr, threadentry, ts);
+}
+
+static void*
+threadentry(void *v)
+{
+	ThreadStart ts;
+
+	ts = *(ThreadStart*)v;
+	free(v);
+
+	ts.g->stackbase = (uintptr)&ts;
+
+	/*
+	 * libcgo_sys_thread_start set stackguard to stack size;
+	 * change to actual guard pointer.
+	 */
+	ts.g->stackguard = (uintptr)&ts - ts.g->stackguard + 4096;
+
+	crosscall_amd64(ts.m, ts.g, ts.fn);
+	return nil;
+}

src/libcgo/linux_arm.c

+/* unimplemented */

src/libcgo/nacl_386.c

+/* unimplemented */

src/libcgo/util.c

+// Copyright 2009 The Go Authors.  All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+#include "libcgo.h"
+
+/* Stub for calling malloc from the other world */
+void
+_cgo_malloc(void *p)
+{
+	struct a {
+		long long n;
+		void *ret;
+	} *a = p;
+
+	a->ret = malloc(a->n);
+}
+
+/* Stub for creating a new thread */
+void
+libcgo_thread_start(ThreadStart *arg)
+{
+	ThreadStart *ts;
+
+	/* Make our own copy that can persist after we return. */
+	ts = malloc(sizeof *ts);
+	if(ts == nil) {
+		fprintf(stderr, "libcgo: out of memory in thread_start\n");
+		abort();
+	}
+	*ts = *arg;
+
+	libcgo_sys_thread_start(ts);	/* OS-dependent half */
+}
+

src/libmach/executable.c

@@ -1126,6 +1126,8 @@ machdotout(int fd, Fhdr *fp, ExecHdr *hp)
 					goto bad;
 				}
 				sect32++;
+				if (strcmp(sect32->sectname, "__nl_symbol_ptr") == 0)
+					sect32++;
 				if (strcmp(sect32->sectname, "__bss") == 0) {
 					bsssize = swal(sect32->size);
 				} else {

src/make.bash

@@ -19,7 +19,7 @@ rm -f $GOBIN/quietgcc
 cp quietgcc.bash $GOBIN/quietgcc
 chmod +x $GOBIN/quietgcc
 
-for i in lib9 libbio libmach libregexp cmd pkg cmd/ebnflint cmd/godoc cmd/gofmt
+for i in lib9 libbio libmach libregexp cmd pkg libcgo cmd/cgo cmd/ebnflint cmd/godoc cmd/gofmt
 do
 	# The ( ) here are to preserve the current directory
 	# for the next round despite the cd $i below.

src/pkg/runtime/386/asm.s

@@ -9,10 +9,19 @@ TEXT _rt0_386(SB),7,$0
 	MOVL	0(SP), AX		// argc
 	LEAL	4(SP), BX		// argv
 	SUBL	$128, SP		// plenty of scratch
-	ANDL	$~7, SP
+	ANDL	$~15, SP
 	MOVL	AX, 120(SP)		// save argc, argv away
 	MOVL	BX, 124(SP)
 
+	// if there is an initcgo, call it to let it
+	// initialize and to set up GS.  if not,
+	// we set up GS ourselves.
+	MOVL	initcgo(SB), AX
+	TESTL	AX, AX
+	JZ	3(PC)
+	CALL	AX
+	JMP	ok
+
 	// set up %gs
 	CALL	ldt0setup(SB)
 
@@ -21,9 +30,8 @@ TEXT _rt0_386(SB),7,$0
 	MOVL	tls0(SB), AX
 	CMPL	AX, $0x123
 	JEQ	ok
-	MOVL	AX, 0
+	MOVL	AX, 0	// abort
 ok:
-
 	// set up m and g "registers"
 	LEAL	g0(SB), CX
 	MOVL	CX, g
@@ -285,13 +293,29 @@ TEXT ldt0setup(SB),7,$16
 	CALL	setldt(SB)
 	RET
 
-GLOBL m0+0(SB), $1024
-GLOBL g0+0(SB), $1024
-
-GLOBL tls0+0(SB), $32
-
 TEXT emptyfunc(SB),0,$0
 	RET
 
 TEXT	abort(SB),7,$0
 	INT $0x3
+
+// runcgo(void(*fn)(void*), void *arg)
+// Just call fn(arg), but first align the stack
+// appropriately for the gcc ABI.
+TEXT	runcgo(SB),7,$16
+	MOVL	fn+0(FP), AX
+	MOVL	arg+4(FP), BX
+	MOVL	SP, CX
+	ANDL	$~15, SP	// alignment for gcc ABI
+	MOVL	CX, 4(SP)
+	MOVL	BX, 0(SP)
+	CALL	AX
+	MOVL	4(SP), SP
+	RET
+
+
+GLOBL m0(SB), $1024
+GLOBL g0(SB), $1024
+GLOBL tls0(SB), $32
+GLOBL initcgo(SB), $4
+

src/pkg/runtime/Makefile

@@ -83,8 +83,8 @@ clean: clean-local
 clean-local:
 	rm -f runtime.acid cgo2c */asm.h
 
-$(GOARCH)/asm.h: runtime.acid mkasmh
-	./mkasmh >$@.x
+$(GOARCH)/asm.h: runtime.acid mkasmh.sh
+	./mkasmh.sh >$@.x
 	mv -f $@.x $@
 
 cgo2c: cgo2c.c

src/pkg/runtime/amd64/asm.s

@@ -270,3 +270,23 @@ TEXT jmpdefer(SB), 7, $0
 	LEAQ	-8(BX), SP	// caller sp after CALL
 	SUBQ	$5, (SP)	// return to CALL again
 	JMP	AX	// but first run the deferred function
+
+// runcgo(void(*fn)(void*), void *arg)
+// Call fn(arg), but align the stack
+// appropriately for the gcc ABI
+// and also save g and m across the call,
+// since the foreign code might reuse them.
+TEXT runcgo(SB),7,$32
+	MOVQ	fn+0(FP),AX
+	MOVQ	arg+8(FP),DI	// DI = first argument in AMD64 ABI
+	MOVQ	SP, CX
+	ANDQ	$~15, SP	// alignment for gcc ABI
+	MOVQ	g, 24(SP)	// save old g, m, SP
+	MOVQ	m, 16(SP)
+	MOVQ	CX, 8(SP)
+	CALL	AX
+	MOVQ	16(SP), m	// restore
+	MOVQ	24(SP), g
+	MOVQ	8(SP), SP
+	RET
+

src/pkg/runtime/cgocall.c

@@ -5,39 +5,32 @@
 #include "runtime.h"
 #include "cgocall.h"
 
-Cgo *cgo;	/* filled in by dynamic linker when Cgo is available */
+void *initcgo;	/* filled in by dynamic linker when Cgo is available */
 int64 ncgocall;
+void sys·entersyscall(void);
+void sys·exitsyscall(void);
 
 void
 cgocall(void (*fn)(void*), void *arg)
 {
-	CgoWork w;
-	CgoServer *s;
+	if(initcgo == nil)
+		throw("cgocall unavailable");
 
 	ncgocall++;
 
-	if(cgo == nil)
-		throw("cgocall unavailable");
-
-	noteclear(&w.note);
-	w.next = nil;
-	w.fn = fn;
-	w.arg = arg;
-	lock(&cgo->lock);
-	if((s = cgo->idle) != nil) {
-		cgo->idle = s->next;
-		s->work = &w;
-		unlock(&cgo->lock);
-		notewakeup(&s->note);
-	} else {
-		if(cgo->whead == nil) {
-			cgo->whead = &w;
-		} else
-			cgo->wtail->next = &w;
-		cgo->wtail = &w;
-		unlock(&cgo->lock);
-	}
-	notesleep(&w.note);
+	/*
+	 * Announce we are entering a system call
+	 * so that the scheduler knows to create another
+	 * M to run goroutines while we are in the
+	 * foreign code.
+	 */
+	sys·entersyscall();
+	g->cgofn = fn;
+	g->cgoarg = arg;
+	g->status = Gcgocall;
+	gosched();
+	sys·exitsyscall();
+	return;
 }
 
 void

src/pkg/runtime/cgocall.h

@@ -4,39 +4,8 @@
 
 /*
  * Cgo interface.
- * Dynamically linked shared libraries compiled with gcc
- * know these data structures and functions too.
- * See ../../libcgo/cgocall.c
  */
 
-typedef struct CgoWork CgoWork;
-typedef struct CgoServer CgoServer;
-typedef struct Cgo Cgo;
-
-struct Cgo
-{
-	Lock lock;
-	CgoServer *idle;
-	CgoWork *whead;
-	CgoWork *wtail;
-};
-
-struct CgoServer
-{
-	CgoServer *next;
-	Note note;
-	CgoWork *work;
-};
-
-struct CgoWork
-{
-	CgoWork *next;
-	Note note;
-	void (*fn)(void*);
-	void *arg;
-};
-
 void cgocall(void (*fn)(void*), void*);
-
 void *cmalloc(uintptr);
 void cfree(void*);

src/pkg/runtime/darwin/386/sys.s

@@ -137,9 +137,6 @@ TEXT bsdthread_start(SB),7,$0
 	POPL	AX
 	POPL	AX
 	POPAL
-	SHLL	$3, DI	// segment# is ldt*8 + 7.
-	ADDL	$7, DI
-	MOVW	DI, GS
 
 	// Now segment is established.  Initialize m, g.
 	MOVL	AX, g
@@ -243,36 +240,51 @@ int i386_set_ldt(int, const union ldt_entry *, int);
 
 // setldt(int entry, int address, int limit)
 TEXT setldt(SB),7,$32
+	MOVL	address+4(FP), BX	// aka base
+	MOVL	limit+8(FP), CX
+
+	/*
+	 * When linking against the system libraries,
+	 * we use its pthread_create and let it set up %gs
+	 * for us.  When we do that, the private storage
+	 * we get is not at 0(GS) but at 0x468(GS).
+	 * To insulate the rest of the tool chain from this ugliness,
+	 * 8l rewrites 0(GS) into 0x468(GS) for us.
+	 * To accommodate that rewrite, we translate the
+	 * address and limit here so that 0x468(GS) maps to 0(address).
+	 *
+	 * See ../../../../libcgo/darwin_386.c for the derivation
+	 * of the constant.
+	 */
+	SUBL	$0x468, BX
+	ADDL	$0x468, CX
+
 	// set up data_desc
 	LEAL	16(SP), AX	// struct data_desc
 	MOVL	$0, 0(AX)
 	MOVL	$0, 4(AX)
 
-	MOVL	address+4(FP), BX	// aka base
 	MOVW	BX, 2(AX)
 	SHRL	$16, BX
 	MOVB	BX, 4(AX)
 	SHRL	$8, BX
 	MOVB	BX, 7(AX)
 
-	MOVL	limit+8(FP), BX
-	MOVW	BX, 0(AX)
-	SHRL	$16, BX
-	ANDL	$0x0F, BX
-	ORL	$0x40, BX		// 32-bit operand size
-	MOVB	BX, 6(AX)
+	MOVW	CX, 0(AX)
+	SHRL	$16, CX
+	ANDL	$0x0F, CX
+	ORL	$0x40, CX		// 32-bit operand size
+	MOVB	CX, 6(AX)
 
 	MOVL	$0xF2, 5(AX)	// r/w data descriptor, dpl=3, present
 
 	// call i386_set_ldt(entry, desc, 1)
-	MOVL	entry+0(FP), BX
-	MOVL	BX, 0(SP)
+	MOVL	$0xffffffff, 0(SP)	// auto-allocate entry and return in AX
 	MOVL	AX, 4(SP)
 	MOVL	$1, 8(SP)
 	CALL	i386_set_ldt(SB)
 
 	// compute segment selector - (entry*8+7)
-	MOVL	entry+0(FP), AX
 	SHLL	$3, AX
 	ADDL	$7, AX
 	MOVW	AX, GS
@@ -285,3 +297,4 @@ TEXT i386_set_ldt(SB),7,$0
 	CALL	notok(SB)
 	RET
 
+GLOBL tlsoffset(SB),$4

src/pkg/runtime/darwin/thread.c

@@ -144,7 +144,11 @@ notewakeup(Note *n)
 void
 osinit(void)
 {
-	// Register our thread-creation callback (see {amd64,386}/sys.s).
+	// Register our thread-creation callback (see {amd64,386}/sys.s)
+	// but only if we're not using cgo.  If we are using cgo we need
+	// to let the C pthread libary install its own thread-creation callback.
+	extern void (*libcgo_thread_start)(void*);
+	if(libcgo_thread_start == nil)
 		bsdthread_register();
 }
 
@@ -152,7 +156,6 @@ void
 newosproc(M *m, G *g, void *stk, void (*fn)(void))
 {
 	m->tls[0] = m->id;	// so 386 asm can find it
-
 	if(0){
 		printf("newosproc stk=%p m=%p g=%p fn=%p id=%d/%d ostk=%p\n",
 			stk, m, g, fn, m->id, m->tls[0], &m);

src/pkg/runtime/linux/386/rt0.s

@@ -5,11 +5,5 @@
 // Darwin and Linux use the same linkage to main
 
 TEXT	_rt0_386_linux(SB),7,$0
-	MOVL	initcgo(SB), AX
-	TESTL	AX, AX
-	JZ	2(PC)
-	CALL	AX
-
 	JMP	_rt0_386(SB)
 
-GLOBL initcgo(SB), $4

src/pkg/runtime/linux/386/sys.s

@@ -198,15 +198,28 @@ TEXT sigaltstack(SB),7,$-8
 
 // setldt(int entry, int address, int limit)
 TEXT setldt(SB),7,$32
+	MOVL	entry+0(FP), BX	// entry
+	MOVL	address+4(FP), CX	// base address
+
+	/*
+	 * When linking against the system libraries,
+	 * we use its pthread_create and let it set up %gs
+	 * for us.  When we do that, the private storage
+	 * we get is not at 0(GS), 4(GS), but -8(GS), -4(GS).
+	 * To insulate the rest of the tool chain from this
+	 * ugliness, 8l rewrites 0(GS) into -8(GS) for us.
+	 * To accommodate that rewrite, we translate
+	 * the address here and bump the limit to 0xffffffff (no limit)
+	 * so that -8(GS) maps to 0(address).
+	 */
+	ADDL	$0x8, CX	// address
+
 	// set up user_desc
 	LEAL	16(SP), AX	// struct user_desc
-	MOVL	entry+0(FP), BX	// entry
 	MOVL	BX, 0(AX)
-	MOVL	address+4(FP), BX	// base address
-	MOVL	BX, 4(AX)
-	MOVL	limit+8(FP), BX	// limit
-	MOVL	BX, 8(AX)
-	MOVL	$(SEG_32BIT|USEABLE|CONTENTS_DATA), 12(AX)	// flag bits
+	MOVL	CX, 4(AX)
+	MOVL	$0xfffff, 8(AX)
+	MOVL	$(SEG_32BIT|LIMIT_IN_PAGES|USEABLE|CONTENTS_DATA), 12(AX)	// flag bits
 
 	// call modify_ldt
 	MOVL	$1, BX	// func = 1 (write)

src/pkg/runtime/mkasmh.sh

@@ -13,11 +13,17 @@ EOF
 
 case "$GOARCH" in
 386)
-	# The offsets 0 and 4 are known to nacl/thread.c:/^newosproc too.
+	# The offsets 0 and 4 are also known to:
+	#	nacl/thread.c:/^newosproc
+	#	../../cmd/8l/pass.c:/D_GS
+	#	../../libcgo/linux_386.c:/^start
+	#	../../libcgo/darwin_386.c:/^start
 	echo '#define	g	0(GS)'
 	echo '#define	m	4(GS)'
 	;;
 amd64)
+	# These registers are also known to:
+	#	../../libcgo/linux_amd64.c:/^start
 	echo '#define	g	R15'
 	echo '#define	m	R14'
 	;;

src/pkg/runtime/proc.c

@@ -389,7 +389,20 @@ mstart(void)
 	scheduler();
 }
 
-// Kick of new ms as needed (up to mcpumax).
+// When running with cgo, we call libcgo_thread_start
+// to start threads for us so that we can play nicely with
+// foreign code.
+void (*libcgo_thread_start)(void*);
+
+typedef struct CgoThreadStart CgoThreadStart;
+struct CgoThreadStart
+{
+	M *m;
+	G *g;
+	void (*fn)(void);
+};
+
+// Kick off new ms as needed (up to mcpumax).
 // There are already `other' other cpus that will
 // start looking for goroutines shortly.
 // Sched is locked.
@@ -405,6 +418,20 @@ matchmg(void)
 			m = malloc(sizeof(M));
 			m->g0 = malg(8192);
 			m->id = sched.mcount++;
+
+			if(libcgo_thread_start != nil) {
+				CgoThreadStart ts;
+				// pthread_create will make us a stack,
+				// so free the one malg made.
+				stackfree(m->g0->stack0);
+				m->g0->stack0 = nil;
+				m->g0->stackguard = nil;
+				m->g0->stackbase = nil;
+				ts.m = m;
+				ts.g = m->g0;
+				ts.fn = mstart;
+				runcgo(libcgo_thread_start, &ts);
+			} else
 				newosproc(m, m->g0, m->g0->stackbase, mstart);
 		}
 		mnextg(m, g);
@@ -419,6 +446,17 @@ scheduler(void)
 
 	lock(&sched);
 	if(gosave(&m->sched) != 0){
+		gp = m->curg;
+		if(gp->status == Gcgocall){
+			// Runtime call into external code (FFI).
+			// When running with FFI, the scheduler stack is a
+			// native pthread stack, so it suffices to switch to the
+			// scheduler stack and make the call.
+			runcgo(gp->cgofn, gp->cgoarg);
+			gp->status = Grunning;
+			gogo(&gp->sched, 1);
+		}
+
 		// Jumped here via gosave/gogo, so didn't
 		// execute lock(&sched) above.
 		lock(&sched);
@@ -426,8 +464,7 @@ scheduler(void)
 		if(sched.predawn)
 			throw("init sleeping");
 
-		// Just finished running m->curg.
-		gp = m->curg;
+		// Just finished running gp.
 		gp->m = nil;
 		sched.mcpu--;
 

src/pkg/runtime/runtime.h

@@ -94,6 +94,7 @@ enum
 	Gwaiting,
 	Gmoribund,
 	Gdead,
+	Gcgocall,
 };
 enum
 {
@@ -156,11 +157,11 @@ struct	Gobuf
 };
 struct	G
 {
-	byte*	stackguard;	// cannot move - also known to linker, libmach
-	byte*	stackbase;	// cannot move - also known to libmach
+	byte*	stackguard;	// cannot move - also known to linker, libmach, libcgo
+	byte*	stackbase;	// cannot move - also known to libmach, libcgo
 	Defer*	defer;
 	Gobuf	sched;		// cannot move - also known to libmach
-	byte*	stack0;		// first stack segment
+	byte*	stack0;
 	byte*	entry;		// initial function
 	G*	alllink;	// on allg
 	void*	param;		// passed parameter on wakeup
@@ -171,6 +172,8 @@ struct	G
 	bool	readyonstop;
 	M*	m;		// for debuggers, but offset not hard-coded
 	M*	lockedm;
+	void	(*cgofn)(void*);	// for cgo/ffi
+	void	*cgoarg;
 };
 struct	Mem
 {
@@ -375,6 +378,7 @@ void	exit(int32);
 void	breakpoint(void);
 void	gosched(void);
 void	goexit(void);
+void	runcgo(void (*fn)(void*), void*);
 
 #pragma	varargck	argpos	printf	1