netdev - [RFC bpf-next v4 06/12] bpf: verifier: record original instruction index

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Date:   Mon, 31 Dec 2018 17:37:37 -0800
From:   Jakub Kicinski <jakub.kicinski@...ronome.com>
To:     alexei.starovoitov@...il.com, daniel@...earbox.net, yhs@...com
Cc:     netdev@...r.kernel.org, oss-drivers@...ronome.com,
        Jakub Kicinski <jakub.kicinski@...ronome.com>
Subject: [RFC bpf-next v4 06/12] 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@...ronome.com>
Reviewed-by: Quentin Monnet <quentin.monnet@...ronome.com>
---
 include/linux/bpf_verifier.h | 1 +
 kernel/bpf/verifier.c        | 8 +++++---
 2 files changed, 6 insertions(+), 3 deletions(-)

diff --git a/include/linux/bpf_verifier.h b/include/linux/bpf_verifier.h
index c233efc106c6..414d1aeba897 100644
--- a/include/linux/bpf_verifier.h
+++ b/include/linux/bpf_verifier.h
@@ -176,6 +176,7 @@ struct bpf_insn_aux_data {
 	int ctx_field_size; /* the ctx field size for load insn, maybe 0 */
 	int sanitize_stack_off; /* stack slot to be cleared */
 	bool seen; /* this insn was processed by the verifier */
+	unsigned int orig_idx; /* original instruction index */
 };
 
 #define MAX_USED_MAPS 64 /* max number of maps accessed by one eBPF program */
diff --git a/kernel/bpf/verifier.c b/kernel/bpf/verifier.c
index 10f22b2f0e89..3efa9f2285fe 100644
--- a/kernel/bpf/verifier.c
+++ b/kernel/bpf/verifier.c
@@ -7112,7 +7112,7 @@ 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 */
@@ -7127,12 +7127,14 @@ 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];
 
-- 
2.19.2