1 files changed, 82 insertions, 4 deletions
diff --git a/src/pkg/runtime/arm/traceback.c b/src/pkg/runtime/arm/traceback.c
index edddafe86..5d32980f6 100644
--- a/src/pkg/runtime/arm/traceback.c
+++ b/src/pkg/runtime/arm/traceback.c
@@ -4,17 +4,95 @@
 
 #include "runtime.h"
 
-// TODO(rsc): Move this into portable code, with calls to a
-// machine-dependent isclosure() function.
+static int32
+gentraceback(byte *pc0, byte *sp, byte *lr0, G *g, int32 skip, uintptr *pcbuf, int32 m)
+{
+	byte *p;
+	int32 i, n, iter;
+	uintptr pc, lr, tracepc;
+	Stktop *stk;
+	Func *f;
+	
+	pc = (uintptr)pc0;
+	lr = (uintptr)lr0;
+
+	// If the PC is zero, it's likely a nil function call.
+	// Start in the caller's frame.
+	if(pc == 0) {
+		pc = lr;
+		lr = 0;
+	}
+
+	n = 0;
+	stk = (Stktop*)g->stackbase;
+	for(iter = 0; iter < 100 && n < m; iter++) {	// iter avoids looping forever
+		if(pc == (uintptr)·lessstack) {
+			// Hit top of stack segment.  Unwind to next segment.
+			pc = (uintptr)stk->gobuf.pc;
+			sp = stk->gobuf.sp;
+			lr = *(uintptr*)sp;
+			stk = (Stktop*)stk->stackbase;
+			continue;
+		}
+		if(pc <= 0x1000 || (f = findfunc(pc-4)) == nil) {
+			// TODO: Check for closure.
+			break;
+		}
+		
+		// Found an actual function worth reporting.
+		if(skip > 0)
+			skip--;
+		else if(pcbuf != nil)
+			pcbuf[n++] = pc;
+		else {
+			// Print during crash.
+			//	main+0xf /home/rsc/go/src/runtime/x.go:23
+			//		main(0x1, 0x2, 0x3)
+			printf("%S", f->name);
+			if(pc > f->entry)
+				printf("+%p", (uintptr)(pc - f->entry));
+			tracepc = pc;	// back up to CALL instruction for funcline.
+			if(n > 0 && pc > f->entry)
+				tracepc -= sizeof(uintptr);
+			printf(" %S:%d\n", f->src, funcline(f, tracepc));
+			printf("\t%S(", f->name);
+			for(i = 0; i < f->args; i++) {
+				if(i != 0)
+					prints(", ");
+				·printhex(((uintptr*)sp)[1+i]);
+				if(i >= 4) {
+					prints(", ...");
+					break;
+				}
+			}
+			prints(")\n");
+			n++;
+		}
+		
+		if(lr == 0)
+			lr = *(uintptr*)sp;
+		pc = lr;
+		lr = 0;
+		if(f->frame >= 0)
+			sp += f->frame;
+	}
+	return n;		
+}
 
 void
-traceback(byte *pc0, byte *sp, G *g)
+traceback(byte *pc0, byte *sp, byte *lr, G *g)
 {
+	gentraceback(pc0, sp, lr, g, 0, nil, 100);
 }
 
 // func caller(n int) (pc uintptr, file string, line int, ok bool)
 int32
 callers(int32 skip, uintptr *pcbuf, int32 m)
 {
-	return 0;
+	byte *pc, *sp;
+	
+	sp = getcallersp(&skip);
+	pc = ·getcallerpc(&skip);
+
+	return gentraceback(pc, sp, 0, g, skip, pcbuf, m);
 }