nfp: bpf: add support for bpf_get_prandom_u32()

NFP has a prng register, which we can read to obtain a u32 worth
of pseudo random data.  Generate code for it.

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>

diff --git a/drivers/net/ethernet/netronome/nfp/bpf/fw.h b/drivers/net/ethernet/netronome/nfp/bpf/fw.h
index cfcc7bc..39639ac 100644 (file)
--- a/drivers/net/ethernet/netronome/nfp/bpf/fw.h
+++ b/drivers/net/ethernet/netronome/nfp/bpf/fw.h
@@ -41,6 +41,7 @@ enum bpf_cap_tlv_type {
        NFP_BPF_CAP_TYPE_FUNC           = 1,
        NFP_BPF_CAP_TYPE_ADJUST_HEAD    = 2,
        NFP_BPF_CAP_TYPE_MAPS           = 3,
+       NFP_BPF_CAP_TYPE_RANDOM         = 4,
 };
 
 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 62431a0..4b631e2 100644 (file)
--- a/drivers/net/ethernet/netronome/nfp/bpf/jit.c
+++ b/drivers/net/ethernet/netronome/nfp/bpf/jit.c
@@ -405,7 +405,7 @@ __emit_lcsr(struct nfp_prog *nfp_prog, u16 areg, u16 breg, bool wr, u16 addr,
                FIELD_PREP(OP_LCSR_A_SRC, areg) |
                FIELD_PREP(OP_LCSR_B_SRC, breg) |
                FIELD_PREP(OP_LCSR_WRITE, wr) |
-               FIELD_PREP(OP_LCSR_ADDR, addr) |
+               FIELD_PREP(OP_LCSR_ADDR, addr / 4) |
                FIELD_PREP(OP_LCSR_SRC_LMEXTN, src_lmextn) |
                FIELD_PREP(OP_LCSR_DST_LMEXTN, dst_lmextn);
 
@@ -433,10 +433,16 @@ static void emit_csr_wr(struct nfp_prog *nfp_prog, swreg src, u16 addr)
                return;
        }
 
-       __emit_lcsr(nfp_prog, reg.areg, reg.breg, true, addr / 4,
+       __emit_lcsr(nfp_prog, reg.areg, reg.breg, true, addr,
                    false, reg.src_lmextn);
 }
 
+/* CSR value is read in following immed[gpr, 0] */
+static void __emit_csr_rd(struct nfp_prog *nfp_prog, u16 addr)
+{
+       __emit_lcsr(nfp_prog, 0, 0, false, addr, false, false);
+}
+
 static void emit_nop(struct nfp_prog *nfp_prog)
 {
        __emit_immed(nfp_prog, UR_REG_IMM, UR_REG_IMM, 0, 0, 0, 0, 0, 0, 0);
@@ -1398,6 +1404,18 @@ map_call_stack_common(struct nfp_prog *nfp_prog, struct nfp_insn_meta *meta)
        return 0;
 }
 
+static int
+nfp_get_prandom_u32(struct nfp_prog *nfp_prog, struct nfp_insn_meta *meta)
+{
+       __emit_csr_rd(nfp_prog, NFP_CSR_PSEUDO_RND_NUM);
+       /* CSR value is read in following immed[gpr, 0] */
+       emit_immed(nfp_prog, reg_both(0), 0,
+                  IMMED_WIDTH_ALL, false, IMMED_SHIFT_0B);
+       emit_immed(nfp_prog, reg_both(1), 0,
+                  IMMED_WIDTH_ALL, false, IMMED_SHIFT_0B);
+       return 0;
+}
+
 /* --- Callbacks --- */
 static int mov_reg64(struct nfp_prog *nfp_prog, struct nfp_insn_meta *meta)
 {
@@ -2431,6 +2449,8 @@ static int call(struct nfp_prog *nfp_prog, struct nfp_insn_meta *meta)
        case BPF_FUNC_map_update_elem:
        case BPF_FUNC_map_delete_elem:
                return map_call_stack_common(nfp_prog, meta);
+       case BPF_FUNC_get_prandom_u32:
+               return nfp_get_prandom_u32(nfp_prog, meta);
        default:
                WARN_ONCE(1, "verifier allowed unsupported function\n");
                return -EOPNOTSUPP;

diff --git a/drivers/net/ethernet/netronome/nfp/bpf/main.c b/drivers/net/ethernet/netronome/nfp/bpf/main.c
index a7e217c..f221410 100644 (file)
--- a/drivers/net/ethernet/netronome/nfp/bpf/main.c
+++ b/drivers/net/ethernet/netronome/nfp/bpf/main.c
@@ -315,6 +315,14 @@ nfp_bpf_parse_cap_maps(struct nfp_app_bpf *bpf, void __iomem *value, u32 length)
        return 0;
 }
 
+static int
+nfp_bpf_parse_cap_random(struct nfp_app_bpf *bpf, void __iomem *value,
+                        u32 length)
+{
+       bpf->pseudo_random = true;
+       return 0;
+}
+
 static int nfp_bpf_parse_capabilities(struct nfp_app *app)
 {
        struct nfp_cpp *cpp = app->pf->cpp;
@@ -353,6 +361,10 @@ static int nfp_bpf_parse_capabilities(struct nfp_app *app)
                        if (nfp_bpf_parse_cap_maps(app->priv, value, length))
                                goto err_release_free;
                        break;
+               case NFP_BPF_CAP_TYPE_RANDOM:
+                       if (nfp_bpf_parse_cap_random(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 a73b86c..4981c89 100644 (file)
--- a/drivers/net/ethernet/netronome/nfp/bpf/main.h
+++ b/drivers/net/ethernet/netronome/nfp/bpf/main.h
@@ -133,6 +133,8 @@ enum pkt_vec {
  * @helpers.map_lookup:                map lookup helper address
  * @helpers.map_update:                map update helper address
  * @helpers.map_delete:                map delete helper address
+ *
+ * @pseudo_random:     FW initialized the pseudo-random machinery (CSRs)
  */
 struct nfp_app_bpf {
        struct nfp_app *app;
@@ -170,6 +172,8 @@ struct nfp_app_bpf {
                u32 map_update;
                u32 map_delete;
        } helpers;
+
+       bool pseudo_random;
 };
 
 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 486ffd1..06ad53c 100644 (file)
--- a/drivers/net/ethernet/netronome/nfp/bpf/verifier.c
+++ b/drivers/net/ethernet/netronome/nfp/bpf/verifier.c
@@ -209,6 +209,13 @@ nfp_bpf_check_call(struct nfp_prog *nfp_prog, struct bpf_verifier_env *env,
                                          meta->func_id ? &meta->arg2 : NULL))
                        return -EOPNOTSUPP;
                break;
+
+       case BPF_FUNC_get_prandom_u32:
+               if (bpf->pseudo_random)
+                       break;
+               pr_vlog(env, "bpf_get_prandom_u32(): FW doesn't support random number generation\n");
+               return -EOPNOTSUPP;
+
        default:
                pr_vlog(env, "unsupported function id: %d\n", func_id);
                return -EOPNOTSUPP;

diff --git a/drivers/net/ethernet/netronome/nfp/nfp_asm.h b/drivers/net/ethernet/netronome/nfp/nfp_asm.h
index 36524dd..5f2b2f2 100644 (file)
--- a/drivers/net/ethernet/netronome/nfp/nfp_asm.h
+++ b/drivers/net/ethernet/netronome/nfp/nfp_asm.h
@@ -284,6 +284,7 @@ enum lcsr_wr_src {
 #define NFP_CSR_ACT_LM_ADDR1   0x6c
 #define NFP_CSR_ACT_LM_ADDR2   0x94
 #define NFP_CSR_ACT_LM_ADDR3   0x9c
+#define NFP_CSR_PSEUDO_RND_NUM 0x148
 
 /* Software register representation, independent of operand type */
 #define NN_REG_TYPE    GENMASK(31, 24)