classify: use 32 bits hash

classify hash used to be stored as u64 in buffer metadata, use 32 bits
instead:
 - on almost all our supported arch (x86 and arm64) we use crc32c
   intrinsics to compute the final hash: we really get a 32-bits hash
 - the hash itself is used to compute a 32-bits bucket index by masking
   upper bits: we always discard the higher 32-bits
 - this allows to increase the l2 classify buffer metadata padding such
   as it does not overlap with the ip fib_index metadata anymore. This
   overlap is an issue when using the 'set metadata' action in the ip
   ACL node which updates both fields

Type: fix

Change-Id: I5d35bdae97b96c3cae534e859b63950fb500ff50
Signed-off-by: Benoît Ganne <bganne@cisco.com>

4 files changed, 21 insertions, 20 deletions

diff --git a/src/vnet/classify/flow_classify_node.c b/src/vnet/classify/flow_classify_node.c
index 4989bf0a012..c0a29992fb4 100644
--- a/src/vnet/classify/flow_classify_node.c
+++ b/src/vnet/classify/flow_classify_node.c
@@ -184,7 +184,7 @@ flow_classify_inline (vlib_main_t * vm,
 	  u32 table_index0;
 	  vnet_classify_table_t *t0;
 	  vnet_classify_entry_t *e0;
-	  u64 hash0;
+	  u32 hash0;
 	  u8 *h0;
 
 	  /* Stride 3 seems to work best */
@@ -193,7 +193,7 @@ flow_classify_inline (vlib_main_t * vm,
 	      vlib_buffer_t *p1 = vlib_get_buffer (vm, from[3]);
 	      vnet_classify_table_t *tp1;
 	      u32 table_index1;
-	      u64 phash1;
+	      u32 phash1;
 
 	      table_index1 = vnet_buffer (p1)->l2_classify.table_index;
 
diff --git a/src/vnet/classify/ip_classify.c b/src/vnet/classify/ip_classify.c
index a5c044521bf..9454ae91937 100644
--- a/src/vnet/classify/ip_classify.c
+++ b/src/vnet/classify/ip_classify.c
@@ -190,7 +190,7 @@ ip_classify_inline (vlib_main_t * vm,
 	  u32 table_index0;
 	  vnet_classify_table_t *t0;
 	  vnet_classify_entry_t *e0;
-	  u64 hash0;
+	  u32 hash0;
 	  u8 *h0;
 
 	  /* Stride 3 seems to work best */
@@ -199,7 +199,7 @@ ip_classify_inline (vlib_main_t * vm,
 	      vlib_buffer_t *p1 = vlib_get_buffer (vm, from[3]);
 	      vnet_classify_table_t *tp1;
 	      u32 table_index1;
-	      u64 phash1;
+	      u32 phash1;
 
 	      table_index1 = vnet_buffer (p1)->l2_classify.table_index;
 
diff --git a/src/vnet/classify/vnet_classify.c b/src/vnet/classify/vnet_classify.c
index 479d3024631..8281be5bd15 100644
--- a/src/vnet/classify/vnet_classify.c
+++ b/src/vnet/classify/vnet_classify.c
@@ -424,7 +424,7 @@ vnet_classify_add_del (vnet_classify_table_t *t, vnet_classify_entry_t *add_v,
   u32 value_index;
   int rv = 0;
   int i;
-  u64 hash, new_hash;
+  u32 hash, new_hash;
   u32 limit;
   u32 old_log2_pages, new_log2_pages;
   u32 thread_index = vlib_get_thread_index ();
@@ -647,15 +647,15 @@ typedef CLIB_PACKED(struct {
 }) classify_data_or_mask_t;
 /* *INDENT-ON* */
 
-u64
-vnet_classify_hash_packet (vnet_classify_table_t * t, u8 * h)
+u32
+vnet_classify_hash_packet (const vnet_classify_table_t *t, u8 *h)
 {
   return vnet_classify_hash_packet_inline (t, h);
 }
 
 vnet_classify_entry_t *
-vnet_classify_find_entry (vnet_classify_table_t * t,
-			  u8 * h, u64 hash, f64 now)
+vnet_classify_find_entry (const vnet_classify_table_t *t, u8 *h, u32 hash,
+			  f64 now)
 {
   return vnet_classify_find_entry_inline (t, h, hash, now);
 }
@@ -3235,7 +3235,7 @@ test_classify_churn (test_classify_main_t * tm)
   for (i = 0; i < tm->sessions; i++)
     {
       u8 *key_minus_skip;
-      u64 hash;
+      u32 hash;
       vnet_classify_entry_t *e;
 
       ep = tm->entries + i;
diff --git a/src/vnet/classify/vnet_classify.h b/src/vnet/classify/vnet_classify.h
index c61ec8ff055..143833dfb20 100644
--- a/src/vnet/classify/vnet_classify.h
+++ b/src/vnet/classify/vnet_classify.h
@@ -243,7 +243,7 @@ u8 *format_classify_entry (u8 *s, va_list *args);
 u8 *format_classify_table (u8 * s, va_list * args);
 u8 *format_vnet_classify_table (u8 *s, va_list *args);
 
-u64 vnet_classify_hash_packet (vnet_classify_table_t * t, u8 * h);
+u32 vnet_classify_hash_packet (const vnet_classify_table_t *t, u8 *h);
 
 static_always_inline vnet_classify_table_t *
 vnet_classify_table_get (u32 table_index)
@@ -253,8 +253,8 @@ vnet_classify_table_get (u32 table_index)
   return (pool_elt_at_index (vcm->tables, table_index));
 }
 
-static inline u64
-vnet_classify_hash_packet_inline (vnet_classify_table_t *t, const u8 *h)
+static inline u32
+vnet_classify_hash_packet_inline (const vnet_classify_table_t *t, const u8 *h)
 {
   u64 xor_sum;
   ASSERT (t);
@@ -361,7 +361,7 @@ vnet_classify_prefetch_bucket (vnet_classify_table_t * t, u64 hash)
 }
 
 static inline vnet_classify_entry_t *
-vnet_classify_get_entry (vnet_classify_table_t * t, uword offset)
+vnet_classify_get_entry (const vnet_classify_table_t *t, uword offset)
 {
   u8 *hp = clib_mem_get_heap_base (t->mheap);
   u8 *vp = hp + offset;
@@ -383,8 +383,8 @@ vnet_classify_get_offset (vnet_classify_table_t * t,
 }
 
 static inline vnet_classify_entry_t *
-vnet_classify_entry_at_index (vnet_classify_table_t * t,
-			      vnet_classify_entry_t * e, u32 index)
+vnet_classify_entry_at_index (const vnet_classify_table_t *t,
+			      vnet_classify_entry_t *e, u32 index)
 {
   u8 *eu8;
 
@@ -421,8 +421,9 @@ vnet_classify_prefetch_entry (vnet_classify_table_t * t, u64 hash)
   clib_prefetch_load (e);
 }
 
-vnet_classify_entry_t *vnet_classify_find_entry (vnet_classify_table_t * t,
-						 u8 * h, u64 hash, f64 now);
+vnet_classify_entry_t *
+vnet_classify_find_entry (const vnet_classify_table_t *t, u8 *h, u32 hash,
+			  f64 now);
 
 static_always_inline int
 vnet_classify_entry_is_equal (vnet_classify_entry_t *v, const u8 *d, u8 *m,
@@ -529,8 +530,8 @@ vnet_classify_entry_is_equal (vnet_classify_entry_t *v, const u8 *d, u8 *m,
 }
 
 static inline vnet_classify_entry_t *
-vnet_classify_find_entry_inline (vnet_classify_table_t *t, const u8 *h,
-				 u64 hash, f64 now)
+vnet_classify_find_entry_inline (const vnet_classify_table_t *t, const u8 *h,
+				 u32 hash, f64 now)
 {
   vnet_classify_entry_t *v;
   vnet_classify_bucket_t *b;