6 files changed, 71 insertions, 0 deletions

diff --git a/drivers/net/ethernet/netronome/nfp/bpf/fw.h b/drivers/net/ethernet/netronome/nfp/bpf/fw.h
index 4c7972e3db63..e4f9b7ec8528 100644
--- a/drivers/net/ethernet/netronome/nfp/bpf/fw.h
+++ b/drivers/net/ethernet/netronome/nfp/bpf/fw.h
@@ -51,6 +51,7 @@ enum bpf_cap_tlv_type {
 	NFP_BPF_CAP_TYPE_MAPS		= 3,
 	NFP_BPF_CAP_TYPE_RANDOM		= 4,
 	NFP_BPF_CAP_TYPE_QUEUE_SELECT	= 5,
+	NFP_BPF_CAP_TYPE_ADJUST_TAIL	= 6,
 };
 
 struct nfp_bpf_cap_tlv_func {
diff --git a/drivers/net/ethernet/netronome/nfp/bpf/jit.c b/drivers/net/ethernet/netronome/nfp/bpf/jit.c
index 3c22d27de9da..eff57f7d056a 100644
--- a/drivers/net/ethernet/netronome/nfp/bpf/jit.c
+++ b/drivers/net/ethernet/netronome/nfp/bpf/jit.c
@@ -1642,6 +1642,51 @@ static int adjust_head(struct nfp_prog *nfp_prog, struct nfp_insn_meta *meta)
 	return 0;
 }
 
+static int adjust_tail(struct nfp_prog *nfp_prog, struct nfp_insn_meta *meta)
+{
+	u32 ret_einval, end;
+	swreg plen, delta;
+
+	BUILD_BUG_ON(plen_reg(nfp_prog) != reg_b(STATIC_REG_PKT_LEN));
+
+	plen = imm_a(nfp_prog);
+	delta = reg_a(2 * 2);
+
+	ret_einval = nfp_prog_current_offset(nfp_prog) + 9;
+	end = nfp_prog_current_offset(nfp_prog) + 11;
+
+	/* Calculate resulting length */
+	emit_alu(nfp_prog, plen, plen_reg(nfp_prog), ALU_OP_ADD, delta);
+	/* delta == 0 is not allowed by the kernel, add must overflow to make
+	 * length smaller.
+	 */
+	emit_br(nfp_prog, BR_BCC, ret_einval, 0);
+
+	/* if (new_len < 14) then -EINVAL */
+	emit_alu(nfp_prog, reg_none(), plen, ALU_OP_SUB, reg_imm(ETH_HLEN));
+	emit_br(nfp_prog, BR_BMI, ret_einval, 0);
+
+	emit_alu(nfp_prog, plen_reg(nfp_prog),
+		 plen_reg(nfp_prog), ALU_OP_ADD, delta);
+	emit_alu(nfp_prog, pv_len(nfp_prog),
+		 pv_len(nfp_prog), ALU_OP_ADD, delta);
+
+	emit_br(nfp_prog, BR_UNC, end, 2);
+	wrp_immed(nfp_prog, reg_both(0), 0);
+	wrp_immed(nfp_prog, reg_both(1), 0);
+
+	if (!nfp_prog_confirm_current_offset(nfp_prog, ret_einval))
+		return -EINVAL;
+
+	wrp_immed(nfp_prog, reg_both(0), -22);
+	wrp_immed(nfp_prog, reg_both(1), ~0);
+
+	if (!nfp_prog_confirm_current_offset(nfp_prog, end))
+		return -EINVAL;
+
+	return 0;
+}
+
 static int
 map_call_stack_common(struct nfp_prog *nfp_prog, struct nfp_insn_meta *meta)
 {
@@ -3041,6 +3086,8 @@ static int call(struct nfp_prog *nfp_prog, struct nfp_insn_meta *meta)
 	switch (meta->insn.imm) {
 	case BPF_FUNC_xdp_adjust_head:
 		return adjust_head(nfp_prog, meta);
+	case BPF_FUNC_xdp_adjust_tail:
+		return adjust_tail(nfp_prog, meta);
 	case BPF_FUNC_map_lookup_elem:
 	case BPF_FUNC_map_update_elem:
 	case BPF_FUNC_map_delete_elem:
diff --git a/drivers/net/ethernet/netronome/nfp/bpf/main.c b/drivers/net/ethernet/netronome/nfp/bpf/main.c
index cce1d2945a32..970af07f4656 100644
--- a/drivers/net/ethernet/netronome/nfp/bpf/main.c
+++ b/drivers/net/ethernet/netronome/nfp/bpf/main.c
@@ -334,6 +334,14 @@ nfp_bpf_parse_cap_qsel(struct nfp_app_bpf *bpf, void __iomem *value, u32 length)
 	return 0;
 }
 
+static int
+nfp_bpf_parse_cap_adjust_tail(struct nfp_app_bpf *bpf, void __iomem *value,
+			      u32 length)
+{
+	bpf->adjust_tail = true;
+	return 0;
+}
+
 static int nfp_bpf_parse_capabilities(struct nfp_app *app)
 {
 	struct nfp_cpp *cpp = app->pf->cpp;
@@ -380,6 +388,11 @@ static int nfp_bpf_parse_capabilities(struct nfp_app *app)
 			if (nfp_bpf_parse_cap_qsel(app->priv, value, length))
 				goto err_release_free;
 			break;
+		case NFP_BPF_CAP_TYPE_ADJUST_TAIL:
+			if (nfp_bpf_parse_cap_adjust_tail(app->priv, value,
+							  length))
+				goto err_release_free;
+			break;
 		default:
 			nfp_dbg(cpp, "unknown BPF capability: %d\n", type);
 			break;
diff --git a/drivers/net/ethernet/netronome/nfp/bpf/main.h b/drivers/net/ethernet/netronome/nfp/bpf/main.h
index 57573bfa8c03..dbd00982fd2b 100644
--- a/drivers/net/ethernet/netronome/nfp/bpf/main.h
+++ b/drivers/net/ethernet/netronome/nfp/bpf/main.h
@@ -150,6 +150,7 @@ enum pkt_vec {
  *
  * @pseudo_random:	FW initialized the pseudo-random machinery (CSRs)
  * @queue_select:	BPF can set the RX queue ID in packet vector
+ * @adjust_tail:	BPF can simply trunc packet size for adjust tail
  */
 struct nfp_app_bpf {
 	struct nfp_app *app;
@@ -195,6 +196,7 @@ struct nfp_app_bpf {
 
 	bool pseudo_random;
 	bool queue_select;
+	bool adjust_tail;
 };
 
 enum nfp_bpf_map_use {
diff --git a/drivers/net/ethernet/netronome/nfp/bpf/verifier.c b/drivers/net/ethernet/netronome/nfp/bpf/verifier.c
index 49ba0d645d36..a6e9248669e1 100644
--- a/drivers/net/ethernet/netronome/nfp/bpf/verifier.c
+++ b/drivers/net/ethernet/netronome/nfp/bpf/verifier.c
@@ -178,6 +178,13 @@ nfp_bpf_check_call(struct nfp_prog *nfp_prog, struct bpf_verifier_env *env,
 		nfp_record_adjust_head(bpf, nfp_prog, meta, reg2);
 		break;
 
+	case BPF_FUNC_xdp_adjust_tail:
+		if (!bpf->adjust_tail) {
+			pr_vlog(env, "adjust_tail not supported by FW\n");
+			return -EOPNOTSUPP;
+		}
+		break;
+
 	case BPF_FUNC_map_lookup_elem:
 		if (!nfp_bpf_map_call_ok("map_lookup", env, meta,
 					 bpf->helpers.map_lookup, reg1) ||
diff --git a/drivers/net/ethernet/netronome/nfp/nfp_asm.h b/drivers/net/ethernet/netronome/nfp/nfp_asm.h
index cdc4e065f6f5..fad0e62a910c 100644
--- a/drivers/net/ethernet/netronome/nfp/nfp_asm.h
+++ b/drivers/net/ethernet/netronome/nfp/nfp_asm.h
@@ -93,6 +93,7 @@ enum br_mask {
 	BR_BNE = 0x01,
 	BR_BMI = 0x02,
 	BR_BHS = 0x04,
+	BR_BCC = 0x05,
 	BR_BLO = 0x05,
 	BR_BGE = 0x08,
 	BR_BLT = 0x09,