runtime/cgo: get getstackbound for set_stacklo

Change-Id: Ia63a4604449b5e460e6f54c962fb7d6db2bc6a43
Reviewed-on: https://go-review.googlesource.com/c/go/+/519457
Run-TryBot: Ian Lance Taylor <iant@golang.org>
Run-TryBot: Ian Lance Taylor <iant@google.com>
Auto-Submit: Ian Lance Taylor <iant@google.com>
TryBot-Result: Gopher Robot <gobot@golang.org>
Reviewed-by: Cherry Mui <cherryyz@google.com>
Reviewed-by: Ian Lance Taylor <iant@google.com>

1 files changed, 7 insertions, 11 deletions

diff --git a/src/runtime/cgo/gcc_libinit.c b/src/runtime/cgo/gcc_libinit.c
index f6c930209e..68f4a02379 100644
--- a/src/runtime/cgo/gcc_libinit.c
+++ b/src/runtime/cgo/gcc_libinit.c
@@ -85,20 +85,18 @@ _cgo_wait_runtime_init_done(void) {
 // _cgo_set_stacklo sets g->stacklo based on the stack size.
 // This is common code called from x_cgo_init, which is itself
 // called by rt0_go in the runtime package.
-void _cgo_set_stacklo(G *g, pthread_attr_t *pattr)
+void _cgo_set_stacklo(G *g, uintptr *pbounds)
 {
-	pthread_attr_t attr;
-	size_t size;
+	uintptr bounds[2];
 
-	// pattr can be passed in by the caller; see gcc_linux_amd64.c.
-	if (pattr == NULL) {
-		pattr = &attr;
+	// pbounds can be passed in by the caller; see gcc_linux_amd64.c.
+	if (pbounds == NULL) {
+		pbounds = &bounds[0];
 	}
 
-	pthread_attr_init(pattr);
-	pthread_attr_getstacksize(pattr, &size);
+	x_cgo_getstackbound(pbounds);
 
-	g->stacklo = (uintptr)(__builtin_frame_address(0)) - size + 4096;
+	g->stacklo = *pbounds;
 
 	// Sanity check the results now, rather than getting a
 	// morestack on g0 crash.
@@ -106,8 +104,6 @@ void _cgo_set_stacklo(G *g, pthread_attr_t *pattr)
 		fprintf(stderr, "runtime/cgo: bad stack bounds: lo=%p hi=%p\n", (void*)(g->stacklo), (void*)(g->stackhi));
 		abort();
 	}
-
-	pthread_attr_destroy(pattr);
 }
 
 // Store the g into a thread-specific value associated with the pthread key pthread_g.