1 files changed, 85 insertions, 14 deletions

diff --git a/src/pkg/runtime/arm/traceback.c b/src/pkg/runtime/arm/traceback.c
index 8289fdb28..2307e98e8 100644
--- a/src/pkg/runtime/arm/traceback.c
+++ b/src/pkg/runtime/arm/traceback.c
@@ -3,19 +3,27 @@
 // license that can be found in the LICENSE file.
 
 #include "runtime.h"
+#include "malloc.h"
+
+void runtime·deferproc(void);
+void runtime·newproc(void);
+void runtime·newstack(void);
+void runtime·morestack(void);
 
 static int32
-gentraceback(byte *pc0, byte *sp, byte *lr0, G *g, int32 skip, uintptr *pcbuf, int32 m)
+gentraceback(byte *pc0, byte *sp, byte *lr0, G *g, int32 skip, uintptr *pcbuf, int32 max)
 {
 	int32 i, n, iter;
-	uintptr pc, lr, tracepc;
+	uintptr pc, lr, tracepc, x;
+	byte *fp, *p;
 	Stktop *stk;
 	Func *f;
 	
 	pc = (uintptr)pc0;
 	lr = (uintptr)lr0;
-	
-	// If the PC is goexit, it hasn't started yet.
+	fp = nil;
+
+	// If the PC is goexit, the goroutine hasn't started yet.
 	if(pc == (uintptr)runtime·goexit) {
 		pc = (uintptr)g->entry;
 		lr = (uintptr)runtime·goexit;
@@ -30,21 +38,73 @@ gentraceback(byte *pc0, byte *sp, byte *lr0, G *g, int32 skip, uintptr *pcbuf, i
 
 	n = 0;
 	stk = (Stktop*)g->stackbase;
-	for(iter = 0; iter < 100 && n < m; iter++) {	// iter avoids looping forever
+	for(iter = 0; iter < 100 && n < max; iter++) {	// iter avoids looping forever
+		// Typically:
+		//	pc is the PC of the running function.
+		//	sp is the stack pointer at that program counter.
+		//	fp is the frame pointer (caller's stack pointer) at that program counter, or nil if unknown.
+		//	stk is the stack containing sp.
+		//	The caller's program counter is lr, unless lr is zero, in which case it is *(uintptr*)sp.
+		
 		if(pc == (uintptr)runtime·lessstack) {
 			// Hit top of stack segment.  Unwind to next segment.
 			pc = (uintptr)stk->gobuf.pc;
 			sp = stk->gobuf.sp;
-			lr = *(uintptr*)sp;
+			lr = 0;
+			fp = nil;
+			if(pcbuf == nil)
+				runtime·printf("----- stack segment boundary -----\n");
 			stk = (Stktop*)stk->stackbase;
 			continue;
 		}
-		if(pc <= 0x1000 || (f = runtime·findfunc(pc-4)) == nil) {
-			// TODO: Check for closure.
+		
+		if(pc <= 0x1000 || (f = runtime·findfunc(pc)) == nil) {
+			// Dangerous, but worthwhile: see if this is a closure by
+			// decoding the instruction stream.
+			//
+			// We check p < p+4 to avoid wrapping and faulting if
+			// we have lost track of where we are.
+			p = (byte*)pc;
+			if((pc&3) == 0 && p < p+4 &&
+			   runtime·mheap.arena_start < p &&
+			   p+4 < runtime·mheap.arena_used) {
+			   	x = *(uintptr*)p;
+				if((x&0xfffff000) == 0xe49df000) {
+					// End of closure:
+					// MOVW.P frame(R13), R15
+					pc = *(uintptr*)sp;
+					lr = 0;
+					sp += x & 0xfff;
+					fp = nil;
+					continue;
+				}
+				if((x&0xfffff000) == 0xe52de000 && lr == (uintptr)runtime·goexit) {
+					// Beginning of closure.
+					// Closure at top of stack, not yet started.
+					p += 5*4;
+					if((x&0xfff) != 4) {
+						// argument copying
+						p += 7*4;
+					}
+					if((byte*)pc < p && p < p+4 && p+4 < runtime·mheap.arena_used) {
+						pc = *(uintptr*)p;
+						fp = nil;
+						continue;
+					}
+				}
+			}
 			break;
 		}
 		
-		// Found an actual function worth reporting.
+		// Found an actual function.
+		if(lr == 0)
+			lr = *(uintptr*)sp;
+		if(fp == nil) {
+			fp = sp;
+			if(pc > f->entry && f->frame >= 0)
+				fp += f->frame;
+		}
+
 		if(skip > 0)
 			skip--;
 		else if(pcbuf != nil)
@@ -64,7 +124,7 @@ gentraceback(byte *pc0, byte *sp, byte *lr0, G *g, int32 skip, uintptr *pcbuf, i
 			for(i = 0; i < f->args; i++) {
 				if(i != 0)
 					runtime·prints(", ");
-				runtime·printhex(((uintptr*)sp)[1+i]);
+				runtime·printhex(((uintptr*)fp)[1+i]);
 				if(i >= 4) {
 					runtime·prints(", ...");
 					break;
@@ -73,17 +133,28 @@ gentraceback(byte *pc0, byte *sp, byte *lr0, G *g, int32 skip, uintptr *pcbuf, i
 			runtime·prints(")\n");
 			n++;
 		}
+
+		if(pcbuf == nil && f->entry == (uintptr)runtime·newstack && g == m->g0) {
+			runtime·printf("----- newstack called from goroutine %d -----\n", m->curg->goid);
+			pc = (uintptr)m->morepc;
+			sp = (byte*)m->moreargp - sizeof(void*);
+			lr = (uintptr)m->morebuf.pc;
+			fp = m->morebuf.sp;
+			g = m->curg;
+			stk = (Stktop*)g->stackbase;
+			continue;
+		}
 		
-		if(lr == 0)
-			lr = *(uintptr*)sp;
+		// Unwind to next frame.
 		pc = lr;
 		lr = 0;
-		if(f->frame >= 0)
-			sp += f->frame;
+		sp = fp;
+		fp = nil;
 	}
 	return n;		
 }
 
+
 void
 runtime·traceback(byte *pc0, byte *sp, byte *lr, G *g)
 {