runtime: handle non-standard call sequences in arm traceback

R=r
CC=golang-dev
https://golang.org/cl/4191048

diff --git a/src/pkg/runtime/arm/traceback.c b/src/pkg/runtime/arm/traceback.c
index 2307e98e85e26ad91c0a2fe2b3cf60cf63133f47..28d39dcdf62636d3c409b682005a6ad667d4e9c1 100644 (file)
--- a/src/pkg/runtime/arm/traceback.c
+++ b/src/pkg/runtime/arm/traceback.c
@@ -9,6 +9,10 @@ void runtime·deferproc(void);
 void runtime·newproc(void);
 void runtime·newstack(void);
 void runtime·morestack(void);
+void _div(void);
+void _mod(void);
+void _divu(void);
+void _modu(void);
 
 static int32
 gentraceback(byte *pc0, byte *sp, byte *lr0, G *g, int32 skip, uintptr *pcbuf, int32 max)
@@ -113,7 +117,7 @@ gentraceback(byte *pc0, byte *sp, byte *lr0, G *g, int32 skip, uintptr *pcbuf, i
                        // Print during crash.
                        //      main+0xf /home/rsc/go/src/runtime/x.go:23
                        //              main(0x1, 0x2, 0x3)
-                       runtime·printf("%S", f->name);
+                       runtime·printf("[%p] %S", fp, f->name);
                        if(pc > f->entry)
                                runtime·printf("+%p", (uintptr)(pc - f->entry));
                        tracepc = pc;   // back up to CALL instruction for funcline.
@@ -150,6 +154,15 @@ gentraceback(byte *pc0, byte *sp, byte *lr0, G *g, int32 skip, uintptr *pcbuf, i
                lr = 0;
                sp = fp;
                fp = nil;
+               
+               // If this was div or divu or mod or modu, the caller had
+               // an extra 8 bytes on its stack.  Adjust sp.
+               if(f->entry == (uintptr)_div || f->entry == (uintptr)_divu || f->entry == (uintptr)_mod || f->entry == (uintptr)_modu)
+                       sp += 8;
+               
+               // If this was deferproc or newproc, the caller had an extra 12.
+               if(f->entry == (uintptr)runtime·deferproc || f->entry == (uintptr)runtime·newproc)
+                       sp += 12;
        }
        return n;               
 }