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>

1 files changed, 11 insertions, 10 deletions

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;