VPP-1024: rewrite buffer trajectory tracer

Use a proper u16 * vector to capture node indices, since vpp w/
plugins now exceeds 255 graph nodes

Change-Id: Ic48cad676fa3a6116413ddf08c083dd9660783f1
Signed-off-by: Dave Barach <dave@barachs.net>

7 files changed, 161 insertions, 50 deletions

diff --git a/src/vlib/buffer.h b/src/vlib/buffer.h
index e47dbc6d4fd..e5c1d21397b 100644
--- a/src/vlib/buffer.h
+++ b/src/vlib/buffer.h
@@ -142,7 +142,8 @@ typedef struct
   /**< Only valid for first buffer in chain. Current length plus
      total length given here give total number of bytes in buffer chain.
   */
-  u32 opaque2[13];  /**< More opaque data, currently unused */
+  u32 align_pad; /**< available */
+  u32 opaque2[12];  /**< More opaque data, see ../vnet/vnet/buffer.h */
 
   /***** end of second cache line */
     CLIB_CACHE_LINE_ALIGN_MARK (cacheline2);
@@ -512,7 +513,11 @@ serialize_vlib_buffer_n_bytes (serialize_main_t * m)
 #define VLIB_BUFFER_TRACE_TRAJECTORY 0
 
 #if VLIB_BUFFER_TRACE_TRAJECTORY > 0
-#define VLIB_BUFFER_TRACE_TRAJECTORY_INIT(b) (b)->pre_data[0]=0
+extern void (*vlib_buffer_trace_trajectory_cb) (vlib_buffer_t * b, u32 index);
+extern void (*vlib_buffer_trace_trajectory_init_cb) (vlib_buffer_t * b);
+extern void vlib_buffer_trace_trajectory_init (vlib_buffer_t * b);
+#define VLIB_BUFFER_TRACE_TRAJECTORY_INIT(b) \
+  vlib_buffer_trace_trajectory_init (b);
 #else
 #define VLIB_BUFFER_TRACE_TRAJECTORY_INIT(b)
 #endif /* VLIB_BUFFER_TRACE_TRAJECTORY */
diff --git a/src/vlib/main.c b/src/vlib/main.c
index 7875f62ad37..fd9937fe3e6 100644
--- a/src/vlib/main.c
+++ b/src/vlib/main.c
@@ -884,52 +884,32 @@ vlib_elog_main_loop_event (vlib_main_t * vm,
 		/* data to log */ n_vectors);
 }
 
+#if VLIB_BUFFER_TRACE_TRAJECTORY > 0
+void (*vlib_buffer_trace_trajectory_cb) (vlib_buffer_t * b, u32 node_index);
+void (*vlib_buffer_trace_trajectory_init_cb) (vlib_buffer_t * b);
+
 void
-vlib_dump_context_trace (vlib_main_t * vm, u32 bi)
+vlib_buffer_trace_trajectory_init (vlib_buffer_t * b)
 {
-  vlib_node_main_t *vnm = &vm->node_main;
-  vlib_buffer_t *b;
-  u8 i, n;
-
-  if (VLIB_BUFFER_TRACE_TRAJECTORY)
+  if (PREDICT_TRUE (vlib_buffer_trace_trajectory_init_cb != 0))
     {
-      b = vlib_get_buffer (vm, bi);
-      n = b->pre_data[0];
-
-      fformat (stderr, "Context trace for bi %d b 0x%llx, visited %d\n",
-	       bi, b, n);
-
-      if (n == 0 || n > 20)
-	{
-	  fformat (stderr, "n is unreasonable\n");
-	  return;
-	}
-
-
-      for (i = 0; i < n; i++)
-	{
-	  u32 node_index;
-
-	  node_index = b->pre_data[i + 1];
+      (*vlib_buffer_trace_trajectory_init_cb) (b);
+    }
+}
 
-	  if (node_index > vec_len (vnm->nodes))
-	    {
-	      fformat (stderr, "Skip bogus node index %d\n", node_index);
-	      continue;
-	    }
+#endif
 
-	  fformat (stderr, "%v (%d)\n", vnm->nodes[node_index]->name,
-		   node_index);
-	}
-    }
-  else
+static inline void
+add_trajectory_trace (vlib_buffer_t * b, u32 node_index)
+{
+#if VLIB_BUFFER_TRACE_TRAJECTORY > 0
+  if (PREDICT_TRUE (vlib_buffer_trace_trajectory_cb != 0))
     {
-      fformat (stderr,
-	       "in vlib/buffers.h, #define VLIB_BUFFER_TRACE_TRAJECTORY 1\n");
+      (*vlib_buffer_trace_trajectory_cb) (b, node_index);
     }
+#endif
 }
 
-
 static_always_inline u64
 dispatch_node (vlib_main_t * vm,
 	       vlib_node_runtime_t * node,
@@ -995,15 +975,12 @@ dispatch_node (vlib_main_t * vm,
       if (VLIB_BUFFER_TRACE_TRAJECTORY && frame)
 	{
 	  int i;
-	  int log_index;
 	  u32 *from;
 	  from = vlib_frame_vector_args (frame);
 	  for (i = 0; i < frame->n_vectors; i++)
 	    {
 	      vlib_buffer_t *b = vlib_get_buffer (vm, from[i]);
-	      ASSERT (b->pre_data[0] < 32);
-	      log_index = b->pre_data[0]++ + 1;
-	      b->pre_data[log_index] = node->node_index;
+	      add_trajectory_trace (b, node->node_index);
 	    }
 	  n = node->function (vm, node, frame);
 	}
diff --git a/src/vnet.am b/src/vnet.am
index 97964c5132e..d76441fcc79 100644
--- a/src/vnet.am
+++ b/src/vnet.am
@@ -1094,7 +1094,8 @@ nobase_include_HEADERS +=			\
 ########################################
 
 libvnet_la_SOURCES +=                    \
-  vnet/util/radix.c
+  vnet/util/radix.c			 \
+  vnet/util/trajectory.c
 
 ########################################
 # Plugin client library
diff --git a/src/vnet/buffer.h b/src/vnet/buffer.h
index 7567b875248..045328816cd 100644
--- a/src/vnet/buffer.h
+++ b/src/vnet/buffer.h
@@ -317,9 +317,26 @@ typedef struct
 {
   union
   {
+#if VLIB_BUFFER_TRACE_TRAJECTORY > 0
+    /* buffer trajectory tracing */
+    struct
+    {
+      u16 *trajectory_trace;
+    };
+#endif
+    u32 unused[12];
   };
 } vnet_buffer_opaque2_t;
 
+#define vnet_buffer2(b) ((vnet_buffer_opaque2_t *) (b)->opaque2)
+
+/*
+ * The opaque2 field of the vlib_buffer_t is intepreted as a
+ * vnet_buffer_opaque2_t. Hence it should be big enough to accommodate one.
+ */
+STATIC_ASSERT (sizeof (vnet_buffer_opaque2_t) <=
+	       STRUCT_SIZE_OF (vlib_buffer_t, opaque2),
+	       "VNET buffer opaque2 meta-data too large for vlib_buffer");
 
 
 #endif /* included_vnet_buffer_h */
diff --git a/src/vnet/interface.c b/src/vnet/interface.c
index 159ce8c6494..eb5d3d0fced 100644
--- a/src/vnet/interface.c
+++ b/src/vnet/interface.c
@@ -1170,6 +1170,7 @@ vnet_interface_init (vlib_main_t * vm)
   vnet_interface_main_t *im = &vnm->interface_main;
   vlib_buffer_t *b = 0;
   vnet_buffer_opaque_t *o = 0;
+  clib_error_t *error;
 
   /*
    * Keep people from shooting themselves in the foot.
@@ -1250,15 +1251,17 @@ vnet_interface_init (vlib_main_t * vm)
       }
   }
 
-  {
-    clib_error_t *error;
+  if ((error = vlib_call_init_function (vm, vnet_interface_cli_init)))
+    return error;
 
-    if ((error = vlib_call_init_function (vm, vnet_interface_cli_init)))
-      return error;
+  vnm->interface_tag_by_sw_if_index = hash_create (0, sizeof (uword));
 
+#if VLIB_BUFFER_TRACE_TRAJECTORY > 0
+  if ((error = vlib_call_init_function (vm, trajectory_trace_init)))
     return error;
-  }
-  vnm->interface_tag_by_sw_if_index = hash_create (0, sizeof (uword));
+#endif
+
+  return 0;
 }
 
 VLIB_INIT_FUNCTION (vnet_interface_init);
diff --git a/src/vnet/unix/gdb_funcs.c b/src/vnet/unix/gdb_funcs.c
index 32e22d924ba..40d0d663472 100644
--- a/src/vnet/unix/gdb_funcs.c
+++ b/src/vnet/unix/gdb_funcs.c
@@ -190,6 +190,8 @@ show_gdb_command_fn (vlib_main_t * vm,
                      vlib_cli_command_t * cmd)
 {
   vlib_cli_output (vm, "vl(p) returns vec_len(p)");
+  vlib_cli_output (vm, "vb(b) returns vnet_buffer(b) [opaque]");
+  vlib_cli_output (vm, "vb2(b) returns vnet_buffer2(b) [opaque2]");
   vlib_cli_output (vm, "pe(p) returns pool_elts(p)");
   vlib_cli_output (vm, "pifi(p, i) returns pool_is_free_index(p, i)");
   vlib_cli_output (vm, "gdb_show_errors(0|1) dumps error counters");
@@ -217,6 +219,17 @@ vnet_buffer_opaque_t *vb (void *vb_arg)
     return rv;
 }
 
+vnet_buffer_opaque2_t *vb2 (void *vb_arg)
+{
+    vlib_buffer_t *b = (vlib_buffer_t *)vb_arg;
+    vnet_buffer_opaque2_t *rv;
+    
+    rv = vnet_buffer2(b);
+
+    return rv;
+}
+
+
 /* Cafeteria plan, maybe you don't want these functions */
 clib_error_t * 
 gdb_func_init (vlib_main_t * vm) { return 0; } 
diff --git a/src/vnet/util/trajectory.c b/src/vnet/util/trajectory.c
new file mode 100644
index 00000000000..24b51254ecd
--- /dev/null
+++ b/src/vnet/util/trajectory.c
@@ -0,0 +1,95 @@
+/*
+ * Copyright (c) 2017 Cisco and/or its affiliates.
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at:
+ *
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+/** \file
+ * Buffer trace trajectory utilities
+ */
+
+#include <vnet/vnet.h>
+
+/**
+ * Dump a trajectory trace, reasonably easy to call from gdb
+ */
+void
+vnet_dump_trajectory_trace (vlib_main_t * vm, u32 bi)
+{
+#if VLIB_BUFFER_TRACE_TRAJECTORY > 0
+  vlib_node_main_t *vnm = &vm->node_main;
+  vlib_buffer_t *b;
+  u16 *trace;
+  u8 i;
+
+  b = vlib_get_buffer (vm, bi);
+
+  trace = vnet_buffer2 (b)->trajectory_trace;
+
+  fformat (stderr, "Context trace for bi %d b 0x%llx, visited %d\n",
+	   bi, b, vec_len (trace));
+
+  for (i = 0; i < vec_len (trace); i++)
+    {
+      u32 node_index;
+
+      node_index = trace[i];
+
+      if (node_index > vec_len (vnm->nodes))
+	{
+	  fformat (stderr, "Skip bogus node index %d\n", node_index);
+	  continue;
+	}
+
+      fformat (stderr, "%v (%d)\n", vnm->nodes[node_index]->name, node_index);
+    }
+#else
+  fformat (stderr, "in vlib/buffers.h, "
+	   "#define VLIB_BUFFER_TRACE_TRAJECTORY 1\n");
+
+#endif
+}
+
+#if VLIB_BUFFER_TRACE_TRAJECTORY > 0
+
+void
+init_trajectory_trace (vlib_buffer_t * b)
+{
+  vec_validate (vnet_buffer2 (b)->trajectory_trace, 7);
+  _vec_len (vnet_buffer2 (b)->trajectory_trace) = 0;
+}
+
+void
+add_trajectory_trace (vlib_buffer_t * b, u32 node_index)
+{
+  vec_add1 (vnet_buffer2 (b)->trajectory_trace, (u16) node_index);
+}
+
+static clib_error_t *
+trajectory_trace_init (vlib_main_t * vm)
+{
+  vlib_buffer_trace_trajectory_cb = add_trajectory_trace;
+  vlib_buffer_trace_trajectory_init_cb = init_trajectory_trace;
+  return 0;
+}
+
+VLIB_INIT_FUNCTION (trajectory_trace_init);
+
+#endif
+
+/*
+ * fd.io coding-style-patch-verification: ON
+ *
+ * Local Variables:
+ * eval: (c-set-style "gnu")
+ * End:
+ */