8l, runtime: fix Plan 9 386 build.

8l was broken by commit 7ac0d2eed9, it caused .data to be page aligned in the file - which is not how Plan 9 expects things to be.
Also .rodata was layed out in a similar fashion.

Not sure when signame was introduced, but added a stub.
Removed the symo assignment in asm.c as it is not currently used.

Fix runtime breakage after commit 629c065d36 which prefixes all external symbols with runtime·.

R=rsc
CC=golang-dev
https://golang.org/cl/2674041

src/cmd/8l/asm.c

@@ -386,7 +386,6 @@ asmb(void)
 			break;
 		case 2:
 			seek(cout, HEADR+segtext.filelen+segdata.filelen, 0);
-			symo = HEADR+segtext.filelen+segdata.filelen;
 			break;
 		case 3:
 		case 4:

src/cmd/8l/obj.c

@@ -192,7 +192,7 @@ main(int argc, char *argv[])
 		if(INITDAT == -1)
 			INITDAT = 0;
 		if(INITRND == -1)
-			INITRND = 4096;
+			INITRND = 1;
 		break;
 	case 3:	/* MS-DOS .COM */
 		HEADR = 0;

src/cmd/ld/data.c

@@ -739,6 +739,10 @@ address(void)
 	segdata.fileoff = va - segtext.vaddr + segtext.fileoff;
 	if(thechar == '8' && HEADTYPE == 10)	// Windows PE
 		segdata.fileoff = segtext.fileoff + rnd(segtext.len, PEFILEALIGN);
+	if(thechar == '8' && HEADTYPE == 2) {	// Plan 9		
+		segdata.vaddr = va = rnd(va, 4096);
+		segdata.fileoff = segtext.fileoff + segtext.filelen;
+	}
 	for(s=segdata.sect; s != nil; s=s->next) {
 		s->vaddr = va;
 		va += s->len;

src/pkg/runtime/plan9/386/signal.c

@@ -8,3 +8,9 @@ void
 runtime·gettime(int64*, int32*) 
 {
 }
+
+String
+runtime·signame(int32)
+{
+	return runtime·emptystring;
+}

src/pkg/runtime/plan9/mem.c

@@ -20,7 +20,7 @@ runtime·SysAlloc(uintptr ask)
 	
 	// Plan 9 sbrk from /sys/src/libc/9sys/sbrk.c
 	bl = ((uintptr)bloc + Round) & ~Round;
-	if(brk_((void*)(bl + ask)) < 0)
+	if(runtime·brk_((void*)(bl + ask)) < 0)
 		return (void*)-1;
 	bloc = (byte*)bl + ask;
 	return (void*)bl;

src/pkg/runtime/plan9/runtime_defs.go

@@ -0,0 +1,23 @@
+// Copyright 2010 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.
+
+// Go definitions of internal structures. Master is runtime.h
+
+package runtime
+
+type lock struct {
+	key  uint32
+	sema uint32
+}
+
+type usema struct {
+	u uint32
+	k uint32
+}
+
+
+type note struct {
+	wakeup int32
+	sema   usema
+}

src/pkg/runtime/plan9/thread.c

@@ -36,10 +36,10 @@ runtime·newosproc(M *m, G *g, void *stk, void (*fn)(void))
 	m->tls[0] = m->id;	// so 386 asm can find it
 	if(0){
 		runtime·printf("newosproc stk=%p m=%p g=%p fn=%p rfork=%p id=%d/%d ostk=%p\n",
-			stk, m, g, fn, rfork, m->id, m->tls[0], &m);
+			stk, m, g, fn, runtime·rfork, m->id, m->tls[0], &m);
 	}        
 	
-	if (rfork(RFPROC | RFMEM, stk, m, g, fn) < 0 )
+	if (runtime·rfork(RFPROC | RFMEM, stk, m, g, fn) < 0 )
 		runtime·throw("newosproc: rfork failed");
 }
 
@@ -63,10 +63,10 @@ runtime·lock(Lock *l)
 		runtime·throw("lock count");
 	m->locks++;
 	
-	if(xadd(&l->key, 1) == 1)
+	if(runtime·xadd(&l->key, 1) == 1)
 		return; // changed from 0 -> 1; we hold lock
 	// otherwise wait in kernel
-	while(plan9_semacquire(&l->sema, 1) < 0) {
+	while(runtime·plan9_semacquire(&l->sema, 1) < 0) {
 		/* interrupted; try again */
 	}
 }
@@ -78,7 +78,7 @@ runtime·unlock(Lock *l)
 	if(m->locks < 0)
 		runtime·throw("lock count");
 
-	if(xadd(&l->key, -1) == 0)
+	if(runtime·xadd(&l->key, -1) == 0)
 		return; // changed from 1 -> 0: no contention
 	
 	runtime·plan9_semrelease(&l->sema, 1);
@@ -98,8 +98,8 @@ runtime·destroylock(Lock *l)
 void
 runtime·usemacquire(Usema *s)
 {
-	if((int32)xadd(&s->u, -1) < 0)
-		while(plan9_semacquire(&s->k, 1) < 0) {
+	if((int32)runtime·xadd(&s->u, -1) < 0)
+		while(runtime·plan9_semacquire(&s->k, 1) < 0) {
 			/* interrupted; try again */
 		}
 }
@@ -107,7 +107,7 @@ runtime·usemacquire(Usema *s)
 void
 runtime·usemrelease(Usema *s)
 {
-	if((int32)xadd(&s->u, 1) <= 0)
+	if((int32)runtime·xadd(&s->u, 1) <= 0)
 		runtime·plan9_semrelease(&s->k, 1);
 }