code review 906041: runtime: turn divide by zero, nil dereference into panics

src/pkg/runtime/linux/amd64/signal.c

 // Copyright 2009 The Go Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style
 // license that can be found in the LICENSE file.
 
 #include "runtime.h"
 #include "defs.h"
 #include "signals.h"
 #include "os.h"
 
 void
@@ skipping 56 matching lines @@
                 // Have to pass arguments out of band since
                 // augmenting the stack frame would break
                 // the unwinding code.
                 gp->sig = sig;
                 gp->sigcode0 = info->si_code;
                 gp->sigcode1 = ((uintptr*)info)[2];
 
                 sp = (uintptr*)r->rsp;
                 *--sp = r->rip;
                 r->rip = (uintptr)sigpanic;
+                r->rsp = (uintptr)sp;
                 return;
         }
 
         if(sigtab[sig].flags & SigQueue) {
                 if(sigsend(sig) || (sigtab[sig].flags & SigIgnore))
                         return;
                 exit(2);        // SIGINT, SIGTERM, etc
         }
 
         if(panicking)   // traceback already printed
@@ skipping 47 matching lines @@
                         else
                                 sa.sa_handler = (void*)sigignore;
                         if(sigtab[i].flags & SigRestart)
                                 sa.sa_flags |= SA_RESTART;
                         else
                                 sa.sa_flags &= ~SA_RESTART;
                         rt_sigaction(i, &sa, nil, 8);
                 }
         }
 }