src/pkg/runtime/mprof.goc       |  4 ++--
 src/pkg/runtime/proc.c          |  4 ++--
 src/pkg/runtime/traceback_arm.c | 12 ++++++++++++
 src/pkg/runtime/traceback_x86.c | 10 ++++++++++

diff --git a/src/pkg/runtime/mprof.goc b/src/pkg/runtime/mprof.goc
index 5b92cec95c72856053f84bf785cf8875db084dae..4ae74f0c288377de607d5d63ad3f01b5125ec786 100644
--- a/src/pkg/runtime/mprof.goc
+++ b/src/pkg/runtime/mprof.goc
@@ -477,7 +477,7 @@ saveg(uintptr pc, uintptr sp, G *gp, TRecord *r)
 {
 	int32 n;
 	
-	n = runtime·gentraceback((uintptr)pc, (uintptr)sp, 0, gp, 0, r->stk, nelem(r->stk), nil, nil, false);
+	n = runtime·gentraceback(pc, sp, 0, gp, 0, r->stk, nelem(r->stk), nil, nil, false);
 	if(n < nelem(r->stk))
 		r->stk[n] = 0;
 }
@@ -505,7 +505,7 @@ 			saveg(pc, sp, g, r++);
 			for(gp = runtime·allg; gp != nil; gp = gp->alllink) {
 				if(gp == g || gp->status == Gdead)
 					continue;
-				saveg(gp->sched.pc, gp->sched.sp, gp, r++);
+				saveg(~(uintptr)0, ~(uintptr)0, gp, r++);
 			}
 		}
 	
diff --git a/src/pkg/runtime/proc.c b/src/pkg/runtime/proc.c
index de26c72d3d7553243dd79c7e6ffcef95fb5ef8a4..ed3e1e73eebdd1ba7a5556cce834b74b56632647 100644
--- a/src/pkg/runtime/proc.c
+++ b/src/pkg/runtime/proc.c
@@ -276,7 +276,7 @@ 	// Show the current goroutine first, if we haven't already.
 	if((gp = m->curg) != nil && gp != me) {
 		runtime·printf("\n");
 		runtime·goroutineheader(gp);
-		runtime·traceback(gp->sched.pc, gp->sched.sp, gp->sched.lr, gp);
+		runtime·traceback(~(uintptr)0, ~(uintptr)0, 0, gp);
 	}
 
 	for(gp = runtime·allg; gp != nil; gp = gp->alllink) {
@@ -290,7 +290,7 @@ 		if(gp->status == Grunning) {
 			runtime·printf("\tgoroutine running on other thread; stack unavailable\n");
 			runtime·printcreatedby(gp);
 		} else
-			runtime·traceback(gp->sched.pc, gp->sched.sp, gp->sched.lr, gp);
+			runtime·traceback(~(uintptr)0, ~(uintptr)0, 0, gp);
 	}
 }
 
diff --git a/src/pkg/runtime/traceback_arm.c b/src/pkg/runtime/traceback_arm.c
index 341aa20588010d7a3a0574dce69732a431084e7b..8a3685e76c508ee3d0ffa251bfdba5a88aaf3eee 100644
--- a/src/pkg/runtime/traceback_arm.c
+++ b/src/pkg/runtime/traceback_arm.c
@@ -20,6 +20,18 @@ 	Stkframe frame;
 	Stktop *stk;
 	String file;
 
+	if(pc0 == ~(uintptr)0 && sp0 == ~(uintptr)0) { // Signal to fetch saved values from gp.
+		if(gp->syscallstack != (uintptr)nil) {
+			pc0 = gp->syscallpc;
+			sp0 = gp->syscallsp;
+			lr0 = 0;
+		} else {
+			pc0 = gp->sched.pc;
+			sp0 = gp->sched.sp;
+			lr0 = gp->sched.lr;
+		}
+	}
+
 	nprint = 0;
 	runtime·memclr((byte*)&frame, sizeof frame);
 	frame.pc = pc0;
diff --git a/src/pkg/runtime/traceback_x86.c b/src/pkg/runtime/traceback_x86.c
index d658e8f11a94d32184833e38179d9ea5be4795a2..8e3063f43a64a89fe23f064d95059ef89795b4a3 100644
--- a/src/pkg/runtime/traceback_x86.c
+++ b/src/pkg/runtime/traceback_x86.c
@@ -30,6 +30,16 @@ 	Stktop *stk;
 	String file;
 
 	USED(lr0);
+	
+	if(pc0 == ~(uintptr)0 && sp0 == ~(uintptr)0) { // Signal to fetch saved values from gp.
+		if(gp->syscallstack != (uintptr)nil) {
+			pc0 = gp->syscallpc;
+			sp0 = gp->syscallsp;
+		} else {
+			pc0 = gp->sched.pc;
+			sp0 = gp->sched.sp;
+		}
+	}
 
 	nprint = 0;
 	runtime·memclr((byte*)&frame, sizeof frame);