vlib: packet tracer support for pkt thread handoffs

Type: feature

Change-Id: Ia3d9a47679202c2a47cd3746b50e86c6b8627ef6
Signed-off-by: Dave Barach <dave@barachs.net>

7 files changed, 192 insertions, 17 deletions

diff --git a/src/vlib/CMakeLists.txt b/src/vlib/CMakeLists.txt
index acd66359f9b..1cecf5fb17d 100644
--- a/src/vlib/CMakeLists.txt
+++ b/src/vlib/CMakeLists.txt
@@ -52,6 +52,7 @@ add_vpp_library(vlib
   drop.c
   error.c
   format.c
+  handoff_trace.c
   i2c.c
   init.c
   linux/pci.c
diff --git a/src/vlib/buffer.c b/src/vlib/buffer.c
index 21e91026b3e..a49200d1b8f 100644
--- a/src/vlib/buffer.c
+++ b/src/vlib/buffer.c
@@ -112,7 +112,7 @@ format_vlib_buffer (u8 * s, va_list * args)
 		b->total_length_not_including_first_buffer);
 
   if (b->flags & VLIB_BUFFER_IS_TRACED)
-    s = format (s, ", trace 0x%x", b->trace_index);
+    s = format (s, ", trace handle 0x%x", b->trace_handle);
 
   if (a)
     s = format (s, "\n%U%v", format_white_space, indent, a);
diff --git a/src/vlib/buffer.h b/src/vlib/buffer.h
index 0fd57f5275b..c8761af4d20 100644
--- a/src/vlib/buffer.h
+++ b/src/vlib/buffer.h
@@ -158,9 +158,9 @@ typedef union
     /** start of 2nd cache line */
       CLIB_CACHE_LINE_ALIGN_MARK (cacheline1);
 
-    /** Specifies index into trace buffer if VLIB_PACKET_IS_TRACED flag is
+    /** Specifies trace buffer handle if VLIB_PACKET_IS_TRACED flag is
       * set. */
-    u32 trace_index;
+    u32 trace_handle;
 
     /** Only valid for first buffer in chain. Current length plus total length
       * given here give total number of bytes in buffer chain. */
@@ -354,6 +354,44 @@ vlib_buffer_make_headroom (vlib_buffer_t * b, u8 size)
   return vlib_buffer_get_current (b);
 }
 
+/** \brief Construct a trace handle from thread and pool index
+ * @param thread Thread id
+ * @param pool_index Pool index
+ * @return trace handle
+ */
+always_inline u32
+vlib_buffer_make_trace_handle (u32 thread, u32 pool_index)
+{
+  u32 rv;
+  ASSERT (thread < 0xff);
+  ASSERT (pool_index < 0x00FFFFFF);
+  rv = (thread << 24) | (pool_index & 0x00FFFFFF);
+  return rv;
+}
+
+/** \brief Extract the thread id from a trace handle
+ * @param trace_handle the trace handle
+ * @return the thread id
+ */
+always_inline u32
+vlib_buffer_get_trace_thread (vlib_buffer_t * b)
+{
+  u32 trace_handle = b->trace_handle;
+
+  return trace_handle >> 24;
+}
+
+/** \brief Extract the trace (pool) index from a trace handle
+ * @param trace_handle the trace handle
+ * @return the trace index
+ */
+always_inline u32
+vlib_buffer_get_trace_index (vlib_buffer_t * b)
+{
+  u32 trace_handle = b->trace_handle;
+  return trace_handle & 0x00FFFFFF;
+}
+
 /** \brief Retrieve bytes from buffer head
  * @param b     pointer to the buffer
  * @param size  number of bytes to pull
diff --git a/src/vlib/handoff_trace.c b/src/vlib/handoff_trace.c
new file mode 100644
index 00000000000..7a6743885da
--- /dev/null
+++ b/src/vlib/handoff_trace.c
@@ -0,0 +1,125 @@
+/*
+ * handoff_trace.c - used to generate handoff trace records
+ *
+ * Copyright (c) 2019 Cisco Systems 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.
+ */
+#include <vlib/vlib.h>
+#include <vnet/vnet.h>
+#include <vnet/pg/pg.h>
+#include <vppinfra/error.h>
+
+typedef struct
+{
+  u32 prev_thread;
+  u32 prev_trace_index;
+} handoff_trace_t;
+
+/* packet trace format function */
+static u8 *
+format_handoff_trace (u8 * s, va_list * args)
+{
+  CLIB_UNUSED (vlib_main_t * vm) = va_arg (*args, vlib_main_t *);
+  CLIB_UNUSED (vlib_node_t * node) = va_arg (*args, vlib_node_t *);
+  handoff_trace_t *t = va_arg (*args, handoff_trace_t *);
+
+  s = format (s, "HANDED-OFF: from thread %d trace index %d",
+	      t->prev_thread, t->prev_trace_index);
+  return s;
+}
+
+static vlib_node_registration_t handoff_trace_node;
+
+#define foreach_handoff_trace_error \
+_(BUGS, "Warning: packets sent to the handoff trace node!")
+
+typedef enum
+{
+#define _(sym,str) HANDOFF_TRACE_ERROR_##sym,
+  foreach_handoff_trace_error
+#undef _
+    HANDOFF_TRACE_N_ERROR,
+} handoff_trace_error_t;
+
+static char *handoff_trace_error_strings[] = {
+#define _(sym,string) string,
+  foreach_handoff_trace_error
+#undef _
+};
+
+static uword
+handoff_trace_node_fn (vlib_main_t * vm,
+		       vlib_node_runtime_t * node, vlib_frame_t * frame)
+{
+  vlib_buffer_free (vm, vlib_frame_vector_args (frame), frame->n_vectors);
+
+  vlib_node_increment_counter (vm, node->node_index,
+			       HANDOFF_TRACE_ERROR_BUGS, frame->n_vectors);
+
+  return frame->n_vectors;
+}
+
+typedef enum
+{
+  HANDOFF_TRACE_NEXT_DROP,
+  HANDOFF_TRACE_N_NEXT,
+} tdummy_next_t;
+
+/* *INDENT-OFF* */
+VLIB_REGISTER_NODE (handoff_trace_node, static) =
+{
+  .name = "handoff_trace",
+  .function = handoff_trace_node_fn,
+  .vector_size = sizeof (u32),
+  .format_trace = format_handoff_trace,
+  .type = VLIB_NODE_TYPE_INTERNAL,
+  .n_next_nodes = HANDOFF_TRACE_N_NEXT,
+
+  /* edit / add dispositions here */
+  .next_nodes = {
+    [HANDOFF_TRACE_NEXT_DROP] = "error-drop",
+  },
+
+  .n_errors = ARRAY_LEN(handoff_trace_error_strings),
+  .error_strings = handoff_trace_error_strings,
+};
+/* *INDENT-ON* */
+
+void
+vlib_add_handoff_trace (vlib_main_t * vm, vlib_buffer_t * b)
+{
+  u32 prev_thread = vlib_buffer_get_trace_thread (b);
+  u32 prev_trace_index = vlib_buffer_get_trace_index (b);
+  handoff_trace_t *t;
+  vlib_node_runtime_t *node
+    = vlib_node_get_runtime (vm, handoff_trace_node.index);
+
+  vlib_trace_buffer (vm, node, 0 /* fake next frame index */ ,
+		     b, 1 /* folllow chain */ );
+
+  t = vlib_add_trace (vm, node, b, sizeof (*t));
+
+  t->prev_thread = prev_thread;
+  t->prev_trace_index = prev_trace_index;
+}
+
+
+/* *INDENT-ON* */
+
+/*
+ * fd.io coding-style-patch-verification: ON
+ *
+ * Local Variables:
+ * eval: (c-set-style "gnu")
+ * End:
+ */
diff --git a/src/vlib/main.c b/src/vlib/main.c
index 43400f8594c..3c0e754169f 100644
--- a/src/vlib/main.c
+++ b/src/vlib/main.c
@@ -1019,8 +1019,8 @@ format_buffer_metadata (u8 * s, va_list * args)
 	      (u32) (b->error), (u32) (b->ref_count),
 	      (u32) (b->buffer_pool_index));
   s = format (s,
-	      "trace_index: %d, len_not_first_buf: %d\n",
-	      b->trace_index, b->total_length_not_including_first_buffer);
+	      "trace_handle: 0x%x, len_not_first_buf: %d\n",
+	      b->trace_handle, b->total_length_not_including_first_buffer);
   return s;
 }
 
@@ -1091,7 +1091,8 @@ dispatch_pcap_trace (vlib_main_t * vm,
 	  if (PREDICT_FALSE (b->flags & VLIB_BUFFER_IS_TRACED))
 	    {
 	      vlib_trace_header_t **h
-		= pool_elt_at_index (tm->trace_buffer_pool, b->trace_index);
+		= pool_elt_at_index (tm->trace_buffer_pool,
+				     vlib_buffer_get_trace_index (b));
 
 	      vm->pcap_buffer = format (vm->pcap_buffer, "%U%c",
 					format_vlib_trace, vm, h[0], 0);
diff --git a/src/vlib/threads.c b/src/vlib/threads.c
index 297c977c464..91125387248 100644
--- a/src/vlib/threads.c
+++ b/src/vlib/threads.c
@@ -1673,6 +1673,7 @@ vlib_frame_queue_dequeue (vlib_main_t * vm, vlib_frame_queue_main_t * fqm)
 
   while (1)
     {
+      vlib_buffer_t *b;
       if (fq->head == fq->tail)
 	{
 	  fq->head_hint = fq->head;
@@ -1695,6 +1696,11 @@ vlib_frame_queue_dequeue (vlib_main_t * vm, vlib_frame_queue_main_t * fqm)
 
       f = vlib_get_frame_to_node (vm, fqm->node_index);
 
+      /* If the first vector is traced, set the frame trace flag */
+      b = vlib_get_buffer (vm, from[0]);
+      if (b->flags & VLIB_BUFFER_IS_TRACED)
+	f->frame_flags |= VLIB_NODE_FLAG_TRACE;
+
       to = vlib_frame_vector_args (f);
 
       n_left_to_node = elt->n_vectors;
diff --git a/src/vlib/trace_funcs.h b/src/vlib/trace_funcs.h
index 56cbfc7b6a2..257c3a3a4ff 100644
--- a/src/vlib/trace_funcs.h
+++ b/src/vlib/trace_funcs.h
@@ -45,14 +45,12 @@ extern u8 *vnet_trace_dummy;
 always_inline void
 vlib_validate_trace (vlib_trace_main_t * tm, vlib_buffer_t * b)
 {
-  /*
-   * this assert seems right, but goes off constantly.
-   * disabling it appears to make the pain go away
-   */
-  ASSERT (1 || b->flags & VLIB_BUFFER_IS_TRACED);
-  ASSERT (!pool_is_free_index (tm->trace_buffer_pool, b->trace_index));
+  ASSERT (!pool_is_free_index (tm->trace_buffer_pool,
+			       vlib_buffer_get_trace_index (b)));
 }
 
+void vlib_add_handoff_trace (vlib_main_t * vm, vlib_buffer_t * b);
+
 always_inline void *
 vlib_add_trace (vlib_main_t * vm,
 		vlib_node_runtime_t * r, vlib_buffer_t * b, u32 n_data_bytes)
@@ -76,11 +74,15 @@ vlib_add_trace (vlib_main_t * vm,
       return vnet_trace_dummy;
     }
 
+  /* Are we trying to trace a handoff case? */
+  if (PREDICT_FALSE (vlib_buffer_get_trace_thread (b) != vm->thread_index))
+    vlib_add_handoff_trace (vm, b);
+
   vlib_validate_trace (tm, b);
 
   n_data_bytes = round_pow2 (n_data_bytes, sizeof (h[0]));
   n_data_words = n_data_bytes / sizeof (h[0]);
-  vec_add2_aligned (tm->trace_buffer_pool[b->trace_index], h,
+  vec_add2_aligned (tm->trace_buffer_pool[vlib_buffer_get_trace_index (b)], h,
 		    1 + n_data_words, sizeof (h[0]));
 
   h->time = vm->cpu_time_last_node_dispatch;
@@ -100,9 +102,10 @@ always_inline void
 vlib_free_trace (vlib_main_t * vm, vlib_buffer_t * b)
 {
   vlib_trace_main_t *tm = &vm->trace_main;
+  u32 trace_index = vlib_buffer_get_trace_index (b);
   vlib_validate_trace (tm, b);
-  _vec_len (tm->trace_buffer_pool[b->trace_index]) = 0;
-  pool_put_index (tm->trace_buffer_pool, b->trace_index);
+  _vec_len (tm->trace_buffer_pool[trace_index]) = 0;
+  pool_put_index (tm->trace_buffer_pool, trace_index);
 }
 
 always_inline void
@@ -149,7 +152,8 @@ vlib_trace_buffer (vlib_main_t * vm,
   do
     {
       b->flags |= VLIB_BUFFER_IS_TRACED;
-      b->trace_index = h - tm->trace_buffer_pool;
+      b->trace_handle = vlib_buffer_make_trace_handle
+	(vm->thread_index, h - tm->trace_buffer_pool);
     }
   while (follow_chain && (b = vlib_get_next_buffer (vm, b)));
 }
@@ -160,7 +164,7 @@ vlib_buffer_copy_trace_flag (vlib_main_t * vm, vlib_buffer_t * b,
 {
   vlib_buffer_t *b_target = vlib_get_buffer (vm, bi_target);
   b_target->flags |= b->flags & VLIB_BUFFER_IS_TRACED;
-  b_target->trace_index = b->trace_index;
+  b_target->trace_handle = b->trace_handle;
 }
 
 always_inline u32