nfp: bpf: add basic support for atomic adds

Implement atomic add operation for 32 and 64 bit values.  Depend
on the verifier to ensure alignment.  Values have to be kept in
big endian and swapped upon read/write.  For now only support
atomic add of a constant.

Signed-off-by: Jakub Kicinski <jakub.kicinski@netronome.com>
Reviewed-by: Quentin Monnet <quentin.monnet@netronome.com>
Reviewed-by: Jiong Wang <jiong.wang@netronome.com>
Signed-off-by: Alexei Starovoitov <ast@kernel.org>

1 files changed, 42 insertions, 3 deletions

diff --git a/drivers/net/ethernet/netronome/nfp/bpf/offload.c b/drivers/net/ethernet/netronome/nfp/bpf/offload.c
index 0a7732385469..42d98792bd25 100644
--- a/drivers/net/ethernet/netronome/nfp/bpf/offload.c
+++ b/drivers/net/ethernet/netronome/nfp/bpf/offload.c
@@ -164,6 +164,41 @@ static int nfp_bpf_destroy(struct nfp_net *nn, struct bpf_prog *prog)
 	return 0;
 }
 
+/* Atomic engine requires values to be in big endian, we need to byte swap
+ * the value words used with xadd.
+ */
+static void nfp_map_bpf_byte_swap(struct nfp_bpf_map *nfp_map, void *value)
+{
+	u32 *word = value;
+	unsigned int i;
+
+	for (i = 0; i < DIV_ROUND_UP(nfp_map->offmap->map.value_size, 4); i++)
+		if (nfp_map->use_map[i] == NFP_MAP_USE_ATOMIC_CNT)
+			word[i] = (__force u32)cpu_to_be32(word[i]);
+}
+
+static int
+nfp_bpf_map_lookup_entry(struct bpf_offloaded_map *offmap,
+			 void *key, void *value)
+{
+	int err;
+
+	err = nfp_bpf_ctrl_lookup_entry(offmap, key, value);
+	if (err)
+		return err;
+
+	nfp_map_bpf_byte_swap(offmap->dev_priv, value);
+	return 0;
+}
+
+static int
+nfp_bpf_map_update_entry(struct bpf_offloaded_map *offmap,
+			 void *key, void *value, u64 flags)
+{
+	nfp_map_bpf_byte_swap(offmap->dev_priv, value);
+	return nfp_bpf_ctrl_update_entry(offmap, key, value, flags);
+}
+
 static int
 nfp_bpf_map_get_next_key(struct bpf_offloaded_map *offmap,
 			 void *key, void *next_key)
@@ -183,8 +218,8 @@ nfp_bpf_map_delete_elem(struct bpf_offloaded_map *offmap, void *key)
 
 static const struct bpf_map_dev_ops nfp_bpf_map_ops = {
 	.map_get_next_key	= nfp_bpf_map_get_next_key,
-	.map_lookup_elem	= nfp_bpf_ctrl_lookup_entry,
-	.map_update_elem	= nfp_bpf_ctrl_update_entry,
+	.map_lookup_elem	= nfp_bpf_map_lookup_entry,
+	.map_update_elem	= nfp_bpf_map_update_entry,
 	.map_delete_elem	= nfp_bpf_map_delete_elem,
 };
 
@@ -192,6 +227,7 @@ static int
 nfp_bpf_map_alloc(struct nfp_app_bpf *bpf, struct bpf_offloaded_map *offmap)
 {
 	struct nfp_bpf_map *nfp_map;
+	unsigned int use_map_size;
 	long long int res;
 
 	if (!bpf->maps.types)
@@ -226,7 +262,10 @@ nfp_bpf_map_alloc(struct nfp_app_bpf *bpf, struct bpf_offloaded_map *offmap)
 		return -ENOMEM;
 	}
 
-	nfp_map = kzalloc(sizeof(*nfp_map), GFP_USER);
+	use_map_size = DIV_ROUND_UP(offmap->map.value_size, 4) *
+		       FIELD_SIZEOF(struct nfp_bpf_map, use_map[0]);
+
+	nfp_map = kzalloc(sizeof(*nfp_map) + use_map_size, GFP_USER);
 	if (!nfp_map)
 		return -ENOMEM;