build: fix elf builds

Corrections due to new strict type rules for data+bss.
Also disable misc/cgo/cdefstest since you can't compile C code anymore.

TBR=iant
CC=golang-codereviews
https://golang.org/cl/148050044

include/link.h

@@ -204,10 +204,10 @@ enum
 	SELFSECT,
 	SMACHO,	/* Mach-O __nl_symbol_ptr */
 	SMACHOGOT,
+	SWINDOWS,
 	SNOPTRDATA,
 	SINITARR,
 	SDATA,
-	SWINDOWS,
 	SBSS,
 	SNOPTRBSS,
 	STLSBSS,

src/cmd/ld/data.c

@@ -625,6 +625,7 @@ addstrdata(char *name, char *value)
 	sp = linklookup(ctxt, p, 0);
 	free(p);
 	addstring(sp, value);
+	sp->type = SRODATA;
 
 	s = linklookup(ctxt, name, 0);
 	s->size = 0;
@@ -816,9 +817,15 @@ proggenaddsym(ProgGen *g, LSym *s)
 	proggenskip(g, g->pos, s->value - g->pos);
 	g->pos += s->value - g->pos;
 
-	if(s->gotype == nil && s->size >= PtrSize) {
+	// The test for names beginning with . here is meant
+	// to keep .dynamic and .dynsym from turning up as
+	// conservative symbols. They should be marked SELFSECT
+	// and not SDATA, but sometimes that doesn't happen.
+	// Leave debugging the SDATA issue for the Go rewrite.
+
+	if(s->gotype == nil && s->size >= PtrSize && s->name[0] != '.') {
 		// conservative scan
-		diag("missing Go type information for global symbol: %s", s->name);
+		diag("missing Go type information for global symbol: %s size %d", s->name, (int)s->size);
 		if((s->size%PtrSize) || (g->pos%PtrSize))
 			diag("proggenaddsym: unaligned conservative symbol %s: size=%lld pos=%lld",
 				s->name, s->size, g->pos);
@@ -834,7 +841,7 @@ proggenaddsym(ProgGen *g, LSym *s)
 			proggenarrayend(g);
 		}
 		g->pos = s->value + size;
-	} else if(s->gotype == nil || decodetype_noptr(s->gotype) || s->size < PtrSize) {
+	} else if(s->gotype == nil || decodetype_noptr(s->gotype) || s->size < PtrSize || s->name[0] == '.') {
 		// no scan
 		if(s->size < 32*PtrSize) {
 			// Emit small symbols as data.

src/cmd/ld/lib.c

@@ -221,8 +221,10 @@ loadlib(void)
 		// Provided by the code that imports the package.
 		// Since we are simulating the import, we have to provide this string.
 		cgostrsym = "go.string.\"runtime/cgo\"";
-		if(linkrlookup(ctxt, cgostrsym, 0) == nil)
+		if(linkrlookup(ctxt, cgostrsym, 0) == nil) {
 			addstrdata(cgostrsym, "runtime/cgo");
+			linklookup(ctxt, cgostrsym, 0)->type = SRODATA;
+		}
 	}
 
 	if(linkmode == LinkAuto) {

src/run.bash

@@ -167,10 +167,13 @@ esac
 # This tests cgo -cdefs. That mode is not supported,
 # so it's okay if it doesn't work on some systems.
 # In particular, it works badly with clang on OS X.
-[ "$CGO_ENABLED" != 1 ] || [ "$GOOS" == darwin ] ||
-(xcd ../misc/cgo/testcdefs
-./test.bash || exit 1
-) || exit $?
+# It doesn't work at all now that we disallow C code
+# outside runtime. Once runtime has no C code it won't
+# even be necessary.
+# [ "$CGO_ENABLED" != 1 ] || [ "$GOOS" == darwin ] ||
+# (xcd ../misc/cgo/testcdefs
+# ./test.bash || exit 1
+# ) || exit $?
 
 [ "$CGO_ENABLED" != 1 ] || [ "$GOOS" == darwin ] ||
 (xcd ../misc/cgo/testgodefs

src/runtime/vdso_linux_amd64.c

@@ -3,6 +3,7 @@
 // license that can be found in the LICENSE file.
 
 #include "runtime.h"
+#include "textflag.h"
 
 // Look up symbols in the Linux vDSO.
 
@@ -171,14 +172,18 @@ struct vdso_info {
 	Elf64_Verdef *verdef;
 };
 
+#pragma dataflag NOPTR
 static version_key linux26 = { (byte*)"LINUX_2.6", 0x3ae75f6 };
 
 // initialize with vsyscall fallbacks
+#pragma dataflag NOPTR
 void* runtime·__vdso_time_sym = (void*)0xffffffffff600400ULL;
+#pragma dataflag NOPTR
 void* runtime·__vdso_gettimeofday_sym = (void*)0xffffffffff600000ULL;
+#pragma dataflag NOPTR
 void* runtime·__vdso_clock_gettime_sym = (void*)0;
 
-#define SYM_KEYS_COUNT 3
+#pragma dataflag NOPTR
 static symbol_key sym_keys[] = {
 	{ (byte*)"__vdso_time", 0xa33c485, &runtime·__vdso_time_sym },
 	{ (byte*)"__vdso_gettimeofday", 0x315ca59, &runtime·__vdso_gettimeofday_sym },
@@ -301,7 +306,7 @@ vdso_parse_symbols(struct vdso_info *vdso_info, int32 version)
 	if(vdso_info->valid == false)
 		return;
 
-	for(i=0; i<SYM_KEYS_COUNT; i++) {
+	for(i=0; i<nelem(sym_keys); i++) {
 		for(chain = vdso_info->bucket[sym_keys[i].sym_hash % vdso_info->nbucket];
 			chain != 0; chain = vdso_info->chain[chain]) {