nfp: bpf: xdp_adjust_tail support

Add support for adjust_tail.  There are no FW changes needed but add
a FW capability just in case there would be any issue with previously
released FW, or we will have to change the ABI in the future.

The helper is trivial and shouldn't be used too often so just inline
the body of the function.  We add the delta to locally maintained
packet length register and check for overflow, since add of negative
value must overflow if result is positive.  Note that if delta of 0
would be allowed in the kernel this trick stops working and we need
one more instruction to compare lengths before and after the change.

Signed-off-by: Jakub Kicinski <jakub.kicinski@netronome.com>
Reviewed-by: Quentin Monnet <quentin.monnet@netronome.com>
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>

diff --git a/drivers/net/ethernet/netronome/nfp/bpf/fw.h b/drivers/net/ethernet/netronome/nfp/bpf/fw.h
index 4c7972e3db63e32f515bdd7fd9e287fa104fd484..e4f9b7ec8528de851e2ce9777d018ddd11eff3c9 100644 (file)
--- 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 3c22d27de9da723896d2a5a2f21e1bbb54a985d4..eff57f7d056a44ccb51caed4d1bd617ff7fc3319 100644 (file)
--- 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 cce1d2945a320ba799d8aefce267ee7db4dccc0a..970af07f46560649d25a8507626e6d544865f30b 100644 (file)
--- 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 57573bfa8c0314dec11223c91636dca9de070e86..dbd00982fd2b698bfa5bedc1572583890e75fe63 100644 (file)
--- 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 49ba0d645d36df879d6885309603426c383a17e6..a6e9248669e141d4d19f0536eed52adf6ef78d90 100644 (file)
--- 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 cdc4e065f6f50d8dff19dbac983547b5b211a804..fad0e62a910ccb6e7f461e04f1936f625f38932d 100644 (file)
--- 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,