nfp: bpf: add support for reading map memory

Map memory needs to use 40 bit addressing.  Add handling of such
accesses.  Since 40 bit addresses are formed by using both 32 bit
operands we need to pre-calculate the actual address instead of
adding in the offset inside the instruction, like we did in 32 bit
mode.
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>

drivers/net/ethernet/netronome/nfp/bpf/jit.c

@@ -553,27 +553,51 @@ wrp_reg_subpart(struct nfp_prog *nfp_prog, swreg dst, swreg src, u8 field_len,
 	emit_ld_field_any(nfp_prog, dst, mask, src, sc, offset * 8, true);
 }
 
+static void
+addr40_offset(struct nfp_prog *nfp_prog, u8 src_gpr, swreg offset,
+	      swreg *rega, swreg *regb)
+{
+	if (offset == reg_imm(0)) {
+		*rega = reg_a(src_gpr);
+		*regb = reg_b(src_gpr + 1);
+		return;
+	}
+
+	emit_alu(nfp_prog, imm_a(nfp_prog), reg_a(src_gpr), ALU_OP_ADD, offset);
+	emit_alu(nfp_prog, imm_b(nfp_prog), reg_b(src_gpr + 1), ALU_OP_ADD_C,
+		 reg_imm(0));
+	*rega = imm_a(nfp_prog);
+	*regb = imm_b(nfp_prog);
+}
+
 /* NFP has Command Push Pull bus which supports bluk memory operations. */
 static int nfp_cpp_memcpy(struct nfp_prog *nfp_prog, struct nfp_insn_meta *meta)
 {
 	bool descending_seq = meta->ldst_gather_len < 0;
 	s16 len = abs(meta->ldst_gather_len);
 	swreg src_base, off;
+	bool src_40bit_addr;
 	unsigned int i;
 	u8 xfer_num;
 
 	off = re_load_imm_any(nfp_prog, meta->insn.off, imm_b(nfp_prog));
+	src_40bit_addr = meta->ptr.type == PTR_TO_MAP_VALUE;
 	src_base = reg_a(meta->insn.src_reg * 2);
 	xfer_num = round_up(len, 4) / 4;
 
+	if (src_40bit_addr)
+		addr40_offset(nfp_prog, meta->insn.src_reg, off, &src_base,
+			      &off);
+
 	/* Setup PREV_ALU fields to override memory read length. */
 	if (len > 32)
 		wrp_immed(nfp_prog, reg_none(),
 			  CMD_OVE_LEN | FIELD_PREP(CMD_OV_LEN, xfer_num - 1));
 
 	/* Memory read from source addr into transfer-in registers. */
-	emit_cmd_any(nfp_prog, CMD_TGT_READ32_SWAP, CMD_MODE_32b, 0, src_base,
-		     off, xfer_num - 1, true, len > 32);
+	emit_cmd_any(nfp_prog, CMD_TGT_READ32_SWAP,
+		     src_40bit_addr ? CMD_MODE_40b_BA : CMD_MODE_32b, 0,
+		     src_base, off, xfer_num - 1, true, len > 32);
 
 	/* Move from transfer-in to transfer-out. */
 	for (i = 0; i < xfer_num; i++)
@@ -711,20 +735,20 @@ data_ld(struct nfp_prog *nfp_prog, swreg offset, u8 dst_gpr, int size)
 }
 
 static int
-data_ld_host_order(struct nfp_prog *nfp_prog, u8 src_gpr, swreg offset,
-		   u8 dst_gpr, int size)
+data_ld_host_order(struct nfp_prog *nfp_prog, u8 dst_gpr,
+		   swreg lreg, swreg rreg, int size, enum cmd_mode mode)
 {
 	unsigned int i;
 	u8 mask, sz;
 
-	/* We load the value from the address indicated in @offset and then
+	/* We load the value from the address indicated in rreg + lreg and then
 	 * mask out the data we don't need.  Note: this is little endian!
 	 */
 	sz = max(size, 4);
 	mask = size < 4 ? GENMASK(size - 1, 0) : 0;
 
-	emit_cmd(nfp_prog, CMD_TGT_READ32_SWAP, CMD_MODE_32b, 0,
-		 reg_a(src_gpr), offset, sz / 4 - 1, true);
+	emit_cmd(nfp_prog, CMD_TGT_READ32_SWAP, mode, 0,
+		 lreg, rreg, sz / 4 - 1, true);
 
 	i = 0;
 	if (mask)
@@ -740,6 +764,26 @@ data_ld_host_order(struct nfp_prog *nfp_prog, u8 src_gpr, swreg offset,
 	return 0;
 }
 
+static int
+data_ld_host_order_addr32(struct nfp_prog *nfp_prog, u8 src_gpr, swreg offset,
+			  u8 dst_gpr, u8 size)
+{
+	return data_ld_host_order(nfp_prog, dst_gpr, reg_a(src_gpr), offset,
+				  size, CMD_MODE_32b);
+}
+
+static int
+data_ld_host_order_addr40(struct nfp_prog *nfp_prog, u8 src_gpr, swreg offset,
+			  u8 dst_gpr, u8 size)
+{
+	swreg rega, regb;
+
+	addr40_offset(nfp_prog, src_gpr, offset, &rega, &regb);
+
+	return data_ld_host_order(nfp_prog, dst_gpr, rega, regb,
+				  size, CMD_MODE_40b_BA);
+}
+
 static int
 construct_data_ind_ld(struct nfp_prog *nfp_prog, u16 offset, u16 src, u8 size)
 {
@@ -1778,8 +1822,20 @@ mem_ldx_data(struct nfp_prog *nfp_prog, struct nfp_insn_meta *meta,
 
 	tmp_reg = re_load_imm_any(nfp_prog, meta->insn.off, imm_b(nfp_prog));
 
-	return data_ld_host_order(nfp_prog, meta->insn.src_reg * 2, tmp_reg,
-				  meta->insn.dst_reg * 2, size);
+	return data_ld_host_order_addr32(nfp_prog, meta->insn.src_reg * 2,
+					 tmp_reg, meta->insn.dst_reg * 2, size);
+}
+
+static int
+mem_ldx_emem(struct nfp_prog *nfp_prog, struct nfp_insn_meta *meta,
+	     unsigned int size)
+{
+	swreg tmp_reg;
+
+	tmp_reg = re_load_imm_any(nfp_prog, meta->insn.off, imm_b(nfp_prog));
+
+	return data_ld_host_order_addr40(nfp_prog, meta->insn.src_reg * 2,
+					 tmp_reg, meta->insn.dst_reg * 2, size);
 }
 
 static int
@@ -1803,6 +1859,9 @@ mem_ldx(struct nfp_prog *nfp_prog, struct nfp_insn_meta *meta,
 		return mem_ldx_stack(nfp_prog, meta, size,
 				     meta->ptr.off + meta->ptr.var_off.value);
 
+	if (meta->ptr.type == PTR_TO_MAP_VALUE)
+		return mem_ldx_emem(nfp_prog, meta, size);
+
 	return -EOPNOTSUPP;
 }
 

drivers/net/ethernet/netronome/nfp/bpf/verifier.c

@@ -249,6 +249,7 @@ nfp_bpf_check_ptr(struct nfp_prog *nfp_prog, struct nfp_insn_meta *meta,
 
 	if (reg->type != PTR_TO_CTX &&
 	    reg->type != PTR_TO_STACK &&
+	    reg->type != PTR_TO_MAP_VALUE &&
 	    reg->type != PTR_TO_PACKET) {
 		pr_vlog(env, "unsupported ptr type: %d\n", reg->type);
 		return -EINVAL;
@@ -260,6 +261,13 @@ nfp_bpf_check_ptr(struct nfp_prog *nfp_prog, struct nfp_insn_meta *meta,
 			return err;
 	}
 
+	if (reg->type == PTR_TO_MAP_VALUE) {
+		if (is_mbpf_store(meta)) {
+			pr_info("map writes not supported\n");
+			return -EOPNOTSUPP;
+		}
+	}
+
 	if (meta->ptr.type != NOT_INIT && meta->ptr.type != reg->type) {
 		pr_vlog(env, "ptr type changed for instruction %d -> %d\n",
 			meta->ptr.type, reg->type);