VPP-845: add configurable elog post-mortem dump

Off by default. Enable via cmdline "... vlib { elog-post-mortem-dump }
..."

Change-Id: I2056b9de9b37475f2bfeeb5404da838f1b42645a
Signed-off-by: Dave Barach <dave@barachs.net>

4 files changed, 37 insertions, 4 deletions

diff --git a/src/vlib/main.c b/src/vlib/main.c
index 422d3e2634b..8af1e7a93cc 100644
--- a/src/vlib/main.c
+++ b/src/vlib/main.c
@@ -707,6 +707,24 @@ elog_save_buffer (vlib_main_t * vm,
   return error;
 }
 
+void
+elog_post_mortem_dump (void)
+{
+  vlib_main_t *vm = &vlib_global_main;
+  elog_main_t *em = &vm->elog_main;
+  u8 *filename;
+  clib_error_t *error;
+
+  if (!vm->elog_post_mortem_dump)
+    return;
+
+  filename = format (0, "/tmp/elog_post_mortem.%d%c", getpid (), 0);
+  error = elog_write_file (em, (char *) filename, 1 /* flush ring */ );
+  if (error)
+    clib_error_report (error);
+  vec_free (filename);
+}
+
 /* *INDENT-OFF* */
 VLIB_CLI_COMMAND (elog_save_cli, static) = {
   .path = "event-logger save",
@@ -1642,6 +1660,8 @@ vlib_main_configure (vlib_main_t * vm, unformat_input_t * input)
       else if (unformat (input, "elog-events %d",
 			 &vm->elog_main.event_ring_size))
 	;
+      else if (unformat (input, "elog-post-mortem-dump"))
+	vm->elog_post_mortem_dump = 1;
       else
 	return unformat_parse_error (input);
     }
diff --git a/src/vlib/main.h b/src/vlib/main.h
index 0e8026d17b0..bfa7ddbe6af 100644
--- a/src/vlib/main.h
+++ b/src/vlib/main.h
@@ -177,6 +177,10 @@ typedef struct vlib_main_t
 
   /* debugging */
   volatile int parked_at_barrier;
+
+  /* Attempt to do a post-mortem elog dump */
+  int elog_post_mortem_dump;
+
 } vlib_main_t;
 
 /* Global main structure. */
diff --git a/src/vlib/unix/main.c b/src/vlib/unix/main.c
index 103576db01c..e31ea81583e 100644
--- a/src/vlib/unix/main.c
+++ b/src/vlib/unix/main.c
@@ -409,12 +409,12 @@ unix_config (vlib_main_t * vm, unformat_input_t * input)
 				  format_unformat_error, input);
     }
 
+  error = setup_signal_handlers (um);
+  if (error)
+    return error;
+
   if (!(um->flags & UNIX_FLAG_INTERACTIVE))
     {
-      error = setup_signal_handlers (um);
-      if (error)
-	return error;
-
       openlog (vm->name, LOG_CONS | LOG_PERROR | LOG_PID, LOG_DAEMON);
       clib_error_register_handler (unix_error_handler, um);
 
diff --git a/src/vpp/vnet/main.c b/src/vpp/vnet/main.c
index d6a1232515f..ade32aa1b78 100644
--- a/src/vpp/vnet/main.c
+++ b/src/vpp/vnet/main.c
@@ -253,11 +253,13 @@ plugin_path_config (vlib_main_t * vm, unformat_input_t * input)
 VLIB_CONFIG_FUNCTION (plugin_path_config, "plugin_path");
 
 void vl_msg_api_post_mortem_dump (void);
+void elog_post_mortem_dump (void);
 
 void
 os_panic (void)
 {
   vl_msg_api_post_mortem_dump ();
+  elog_post_mortem_dump ();
   abort ();
 }
 
@@ -280,6 +282,7 @@ os_exit (int code)
       recursion_block = 1;
 
       vl_msg_api_post_mortem_dump ();
+      elog_post_mortem_dump ();
       vhost_user_unmap_all ();
       abort ();
     }
@@ -320,6 +323,12 @@ test_crash_command_fn (vlib_main_t * vm,
 {
   u64 *p = (u64 *) 0xdefec8ed;
 
+  ELOG_TYPE_DECLARE (e) =
+  {
+  .format = "deliberate crash: touching %x",.format_args = "i4",};
+
+  elog (&vm->elog_main, &e, 0xdefec8ed);
+
   *p = 0xdeadbeef;
 
   /* Not so much... */