bpf: verifier: record original instruction index

The communication between the verifier and advanced JITs is based
on instruction indexes.  We have to keep them stable throughout
the optimizations otherwise referring to a particular instruction
gets messy quickly.

Signed-off-by: Jakub Kicinski <jakub.kicinski@netronome.com>
Reviewed-by: Quentin Monnet <quentin.monnet@netronome.com>
Signed-off-by: Alexei Starovoitov <ast@kernel.org>

include/linux/bpf_verifier.h

@@ -187,6 +187,7 @@ struct bpf_insn_aux_data {
 	int sanitize_stack_off; /* stack slot to be cleared */
 	bool seen; /* this insn was processed by the verifier */
 	u8 alu_state; /* used in combination with alu_limit */
+	unsigned int orig_idx; /* original instruction index */
 };
 
 #define MAX_USED_MAPS 64 /* max number of maps accessed by one eBPF program */

kernel/bpf/verifier.c

@@ -7371,7 +7371,7 @@ int bpf_check(struct bpf_prog **prog, union bpf_attr *attr,
 {
 	struct bpf_verifier_env *env;
 	struct bpf_verifier_log *log;
-	int ret = -EINVAL;
+	int i, len, ret = -EINVAL;
 	bool is_priv;
 
 	/* no program is valid */
@@ -7386,12 +7386,14 @@ int bpf_check(struct bpf_prog **prog, union bpf_attr *attr,
 		return -ENOMEM;
 	log = &env->log;
 
+	len = (*prog)->len;
 	env->insn_aux_data =
-		vzalloc(array_size(sizeof(struct bpf_insn_aux_data),
-				   (*prog)->len));
+		vzalloc(array_size(sizeof(struct bpf_insn_aux_data), len));
 	ret = -ENOMEM;
 	if (!env->insn_aux_data)
 		goto err_free_env;
+	for (i = 0; i < len; i++)
+		env->insn_aux_data[i].orig_idx = i;
 	env->prog = *prog;
 	env->ops = bpf_verifier_ops[env->prog->type];