nfp: bpf: reuse verifier log for debug messages

Now that `bpf_verifier_log_write()` is exported from the verifier and
makes it possible to reuse the verifier log to print messages to the
standard output, use this instead of the kernel logs in the nfp driver
for printing error messages occurring at verification time.
Signed-off-by: NQuentin Monnet <quentin.monnet@netronome.com>
Reviewed-by: NJakub Kicinski <jakub.kicinski@netronome.com>
Signed-off-by: NDaniel Borkmann <daniel@iogearbox.net>

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

@@ -31,8 +31,6 @@
  * SOFTWARE.
  */
 
-#define pr_fmt(fmt)	"NFP net bpf: " fmt
-
 #include <linux/bpf.h>
 #include <linux/bpf_verifier.h>
 #include <linux/kernel.h>
@@ -41,6 +39,9 @@
 #include "fw.h"
 #include "main.h"
 
+#define pr_vlog(env, fmt, ...)	\
+	bpf_verifier_log_write(env, "[nfp] " fmt, ##__VA_ARGS__)
+
 struct nfp_insn_meta *
 nfp_bpf_goto_meta(struct nfp_prog *nfp_prog, struct nfp_insn_meta *meta,
 		  unsigned int insn_idx, unsigned int n_insns)
@@ -116,18 +117,18 @@ nfp_bpf_check_call(struct nfp_prog *nfp_prog, struct bpf_verifier_env *env,
 	switch (func_id) {
 	case BPF_FUNC_xdp_adjust_head:
 		if (!bpf->adjust_head.off_max) {
-			pr_warn("adjust_head not supported by FW\n");
+			pr_vlog(env, "adjust_head not supported by FW\n");
 			return -EOPNOTSUPP;
 		}
 		if (!(bpf->adjust_head.flags & NFP_BPF_ADJUST_HEAD_NO_META)) {
-			pr_warn("adjust_head: FW requires shifting metadata, not supported by the driver\n");
+			pr_vlog(env, "adjust_head: FW requires shifting metadata, not supported by the driver\n");
 			return -EOPNOTSUPP;
 		}
 
 		nfp_record_adjust_head(bpf, nfp_prog, meta, reg2);
 		break;
 	default:
-		pr_warn("unsupported function id: %d\n", func_id);
+		pr_vlog(env, "unsupported function id: %d\n", func_id);
 		return -EOPNOTSUPP;
 	}
 
@@ -150,7 +151,7 @@ nfp_bpf_check_exit(struct nfp_prog *nfp_prog,
 		char tn_buf[48];
 
 		tnum_strn(tn_buf, sizeof(tn_buf), reg0->var_off);
-		pr_info("unsupported exit state: %d, var_off: %s\n",
+		pr_vlog(env, "unsupported exit state: %d, var_off: %s\n",
 			reg0->type, tn_buf);
 		return -EINVAL;
 	}
@@ -160,7 +161,7 @@ nfp_bpf_check_exit(struct nfp_prog *nfp_prog,
 	    imm <= TC_ACT_REDIRECT &&
 	    imm != TC_ACT_SHOT && imm != TC_ACT_STOLEN &&
 	    imm != TC_ACT_QUEUED) {
-		pr_info("unsupported exit state: %d, imm: %llx\n",
+		pr_vlog(env, "unsupported exit state: %d, imm: %llx\n",
 			reg0->type, imm);
 		return -EINVAL;
 	}
@@ -171,12 +172,13 @@ nfp_bpf_check_exit(struct nfp_prog *nfp_prog,
 static int
 nfp_bpf_check_stack_access(struct nfp_prog *nfp_prog,
 			   struct nfp_insn_meta *meta,
-			   const struct bpf_reg_state *reg)
+			   const struct bpf_reg_state *reg,
+			   struct bpf_verifier_env *env)
 {
 	s32 old_off, new_off;
 
 	if (!tnum_is_const(reg->var_off)) {
-		pr_info("variable ptr stack access\n");
+		pr_vlog(env, "variable ptr stack access\n");
 		return -EINVAL;
 	}
 
@@ -194,7 +196,7 @@ nfp_bpf_check_stack_access(struct nfp_prog *nfp_prog,
 	if (old_off % 4 == new_off % 4)
 		return 0;
 
-	pr_info("stack access changed location was:%d is:%d\n",
+	pr_vlog(env, "stack access changed location was:%d is:%d\n",
 		old_off, new_off);
 	return -EINVAL;
 }
@@ -209,18 +211,18 @@ 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_PACKET) {
-		pr_info("unsupported ptr type: %d\n", reg->type);
+		pr_vlog(env, "unsupported ptr type: %d\n", reg->type);
 		return -EINVAL;
 	}
 
 	if (reg->type == PTR_TO_STACK) {
-		err = nfp_bpf_check_stack_access(nfp_prog, meta, reg);
+		err = nfp_bpf_check_stack_access(nfp_prog, meta, reg, env);
 		if (err)
 			return err;
 	}
 
 	if (meta->ptr.type != NOT_INIT && meta->ptr.type != reg->type) {
-		pr_info("ptr type changed for instruction %d -> %d\n",
+		pr_vlog(env, "ptr type changed for instruction %d -> %d\n",
 			meta->ptr.type, reg->type);
 		return -EINVAL;
 	}
@@ -241,7 +243,7 @@ nfp_verify_insn(struct bpf_verifier_env *env, int insn_idx, int prev_insn_idx)
 
 	if (meta->insn.src_reg >= MAX_BPF_REG ||
 	    meta->insn.dst_reg >= MAX_BPF_REG) {
-		pr_err("program uses extended registers - jit hardening?\n");
+		pr_vlog(env, "program uses extended registers - jit hardening?\n");
 		return -EINVAL;
 	}