[ES40-developers] [patch] display backtrace on segfault

[Brian W. <bdw...@in...>]

Sometimes I get a segfault when I'm running es40.  I've added code
(specific to g++) which will dump a backtrace and exit.  Of course,
since I've added that code I've not seen a segfault, but I'm hopeful :)

Brian

===================================================================
RCS file: /cvsroot/es40/es40/src/Makefile,v
retrieving revision 1.20
diff -u -r1.20 Makefile
--- Makefile    2 Feb 2008 16:43:01 -0000       1.20
+++ Makefile    7 Feb 2008 14:47:48 -0000
@@ -102,7 +102,7 @@
 #  -O3   -- optimize at level 3
 #  -mtune=<cpu>   -- cpu is one of:  generic, core2, athlon64,
pentium4, etc
 #
-CTUNINGFLAGS = -O3 -mtune=generic 
+CTUNINGFLAGS = -O3 -mtune=generic
 
 #
 # CDEBUGFLAGS - turn on debugging in ES40
@@ -124,8 +124,9 @@
 #   -DDEBUG_KBD                    Turn on keyboard debugging
 #   -DDEBUG_PIC                    Turn on Programmable Interrupt
Controller debugging
 #   -DDEBUG_LPT         Turn on debugging for LPT Port
+#   -DDEBUG_BACKTRACE   Turn on backtrace dump on SIGSEGV
 #
-CDEBUGFLAGS = -g -DHIDE_COUNTER 
+CDEBUGFLAGS = -g -DHIDE_COUNTER -DDEBUG_BACKTRACE
 
 #
 # ES40 Options
@@ -247,4 +248,3 @@
        $(DEPEND) -o.do -a -- $(IDB_CFLAGS) -- $(SRCS)
 clean:
        rm -f es40 es40_idb es40_lss es40_lsm *.o *.do *.mao *.slo *.trc
gui/*.o gui/*.mao gui/*.slo gui/*.do
-
Index: AlphaSim.cpp
===================================================================
RCS file: /cvsroot/es40/es40/src/AlphaSim.cpp,v
retrieving revision 1.39
diff -u -r1.39 AlphaSim.cpp
--- AlphaSim.cpp        5 Feb 2008 10:15:57 -0000       1.39
+++ AlphaSim.cpp        7 Feb 2008 14:47:48 -0000
@@ -180,6 +180,46 @@
   0
 };
 
+
+#ifdef DEBUG_BACKTRACE
+#ifdef __GNUG__
+#include <execinfo.h>
+#include <signal.h>
+#define HAS_BACKTRACE
+
+#define BTCOUNT 100
+void *btbuffer[BTCOUNT];
+
+void segv_handler(int signum) {
+  int nptrs = backtrace(btbuffer, BTCOUNT);
+  char **strings;
+  
+  printf("%%SYS-F-SEGFAULT: The Alpha Simulator has Segfaulted.\n");
+  printf("-SYS-F-SEGFAULT: Backtrace follows.\n");
+
+  printf("backtrace() returned %d addresses.\n",nptrs);
+  strings = backtrace_symbols(btbuffer,nptrs);
+  if(strings==NULL) {
+    perror("backtrace_symbols");
+    exit(1);
+  }
+  
+  for(int i = 0; i < nptrs; i++) {
+    printf("%3d %s\n",nptrs-i, strings[i]);
+  }
+  free(strings);
+  exit(1);
+}
+
+#else
+#warning "Your compiler isn't configured to support backtraces."
+#endif // __GNUG__
+#endif
+
+
+
+
+
 /**
  * Entry point for the application.
  *
@@ -214,6 +254,12 @@
   char *filename = 0;
   FILE *f;
 
+#ifdef HAS_BACKTRACE
+#ifdef __GNUG__
+  signal(SIGSEGV, &segv_handler);
+#endif
+#endif
+
   try 
   {
 #if defined(IDB) && (defined(LS_MASTER) || defined(LS_SLAVE))