[LibOS] Add core-dump info on default signal dispositions

This commit adds default signal dispositions (as per Linux) to all 32
standard signals. It also adds WCOREDUMP bit to correctly inform wait4()
status word.

This commit updates graphene-tests submodules to enable new killXX LTP
regression tests, as well as fix the waitpid05 LTP test. It is important
to update this submodule reference in this commit because otherwise
waitpid05 tests will fail Graphene's CI.

LibOS/shim/src/bookkeep/shim_signal.c

@@ -747,16 +747,20 @@ void append_signal (struct shim_thread * thread, int sig, siginfo_t * info,
     }
 }
 
+#define __WCOREDUMP_BIT 0x80
+
 static void sighandler_kill (int sig, siginfo_t * info, void * ucontext)
 {
+    int sig_without_coredump_bit = sig & ~(__WCOREDUMP_BIT);
+
     __UNUSED(ucontext);
-    debug("killed by %s\n", signal_name(sig));
+    debug("killed by %s\n", signal_name(sig_without_coredump_bit));
 
     if (!info->si_pid)
         switch(sig) {
             case SIGTERM:
             case SIGINT:
-                shim_do_kill(-1, sig);
+                shim_do_kill(-1, sig_without_coredump_bit);
                 break;
         }
 
@@ -764,10 +768,11 @@ static void sighandler_kill (int sig, siginfo_t * info, void * ucontext)
     DkThreadExit();
 }
 
-/* We don't currently implement core dumps, but put a wrapper
- * in case we do in the future */
 static void sighandler_core (int sig, siginfo_t * info, void * ucontext)
 {
+    /* NOTE: This implementation only indicates the core dump for wait4()
+     *       and friends. No actual core-dump file is created. */
+    sig = __WCOREDUMP_BIT | sig;
     sighandler_kill(sig, info, ucontext);
 }
 
@@ -775,24 +780,33 @@ static void (*default_sighandler[NUM_SIGS]) (int, siginfo_t *, void *) =
     {
         /* SIGHUP */    &sighandler_kill,
         /* SIGINT */    &sighandler_kill,
-        /* SIGQUIT */   &sighandler_kill,
-        /* SIGILL */    &sighandler_kill,
+        /* SIGQUIT */   &sighandler_core,
+        /* SIGILL */    &sighandler_core,
         /* SIGTRAP */   &sighandler_core,
-        /* SIGABRT */   &sighandler_kill,
-        /* SIGBUS */    &sighandler_kill,
-        /* SIGFPE */    &sighandler_kill,
+        /* SIGABRT */   &sighandler_core,
+        /* SIGBUS */    &sighandler_core,
+        /* SIGFPE */    &sighandler_core,
         /* SIGKILL */   &sighandler_kill,
-        /* SIGUSR1 */   NULL,
-        /* SIGSEGV */   &sighandler_kill,
-        /* SIGUSR2 */   NULL,
+        /* SIGUSR1 */   &sighandler_kill,
+        /* SIGSEGV */   &sighandler_core,
+        /* SIGUSR2 */   &sighandler_kill,
         /* SIGPIPE */   &sighandler_kill,
         /* SIGALRM */   &sighandler_kill,
         /* SIGTERM */   &sighandler_kill,
-        /* SIGSTKFLT */ NULL,
+        /* SIGSTKFLT */ &sighandler_kill,
         /* SIGCHLD */   NULL,
         /* SIGCONT */   NULL,
         /* SIGSTOP */   NULL,
         /* SIGTSTP */   NULL,
         /* SIGTTIN */   NULL,
         /* SIGTTOU */   NULL,
+        /* SIGURG  */   NULL,
+        /* SIGXCPU */   &sighandler_core,
+        /* SIGXFSZ */   &sighandler_core,
+        /* SIGVTALRM */ &sighandler_kill,
+        /* SIGPROF   */ &sighandler_kill,
+        /* SIGWINCH  */ NULL,
+        /* SIGIO   */   &sighandler_kill,
+        /* SIGPWR  */   &sighandler_kill,
+        /* SIGSYS  */   &sighandler_core
     };

LibOS/shim/src/sys/shim_exit.c

@@ -129,6 +129,7 @@ int thread_exit(struct shim_thread * self, bool send_ipc)
     return 0;
 }
 
+/* note that term_signal argument may contain WCOREDUMP bit (0x80) */
 int try_process_exit (int error_code, int term_signal)
 {
     struct shim_thread * cur_thread = get_cur_thread();