[dev.power64] code review 152570049: all: merge default into dev.power64

src/runtime/cgo/gcc_openbsd_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 <sys/types.h>
 #include <dlfcn.h>
 #include <errno.h>
 #include <pthread.h>
 #include <signal.h>
 #include <string.h>
@@ skipping 74 matching lines @@
 void
 x_cgo_init(G *g, void (*setg)(void*))
 {
         pthread_attr_t attr;
         size_t size;
         void *handle;
 
         setg_gcc = setg;
         pthread_attr_init(&attr);
         pthread_attr_getstacksize(&attr, &size);
-        g->stackguard = (uintptr)&attr - size + 4096;
+        g->stacklo = (uintptr)&attr - size + 4096;
         pthread_attr_destroy(&attr);
 
         // Locate symbol for the system pthread_create function.
         handle = dlopen("libpthread.so", RTLD_LAZY);
         if(handle == NULL) {
                 fprintf(stderr, "dlopen: failed to load libpthread: %s\n", dlerror());
                 abort();
         }
         sys_pthread_create = dlsym(handle, "pthread_create");
         if(sys_pthread_create == NULL) {
@@ skipping 14 matching lines @@
         pthread_t p;
         size_t size;
         int err;
 
         sigfillset(&ign);
         pthread_sigmask(SIG_SETMASK, &ign, &oset);
 
         pthread_attr_init(&attr);
         pthread_attr_getstacksize(&attr, &size);
 
-        ts->g->stackguard = size;
+        // Leave stacklo=0 and set stackhi=size; mstack will do the rest.
+        ts->g->stackhi = size;
         err = sys_pthread_create(&p, &attr, threadentry, ts);
 
         pthread_sigmask(SIG_SETMASK, &oset, nil);
 
         if (err != 0) {
                 fprintf(stderr, "runtime/cgo: pthread_create failed: %s\n", strerror(err));
                 abort();
         }
 }
 
 static void*
 threadentry(void *v)
 {
         ThreadStart ts;
 
         tcb_fixup(0);
 
         ts = *(ThreadStart*)v;
         free(v);
 
-        ts.g->stackbase = (uintptr)&ts;
-
-        /*
-         * _cgo_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.
          */
         setg_gcc((void*)ts.g);
 
         crosscall_amd64(ts.fn);
         return nil;
 }