[PATCH] BPF: replace low-entropy member with macro

[zhongjun@uniontech.com]

From: zhongjun <zhongjun@uniontech.com>

The member orig_idx is a low-entropy once-init invariable data
member. It can be replace by a series of macros.
Replace this member by macros can save memory and cpu-time.

Signed-off-by: Jun Zhong <zhongjun@uniontech.com>
base-commit: 919e659ed12568b5b8ba6c2ffdd82d8d31fc28af
---
 include/linux/bpf_verifier.h | 3 ++-
 kernel/bpf/verifier.c        | 6 ++----
 2 files changed, 4 insertions(+), 5 deletions(-)

diff --git a/include/linux/bpf_verifier.h b/include/linux/bpf_verifier.h
index cf1bb1cf4a7b..8783d90a21bb 100644
--- a/include/linux/bpf_verifier.h
+++ b/include/linux/bpf_verifier.h
@@ -451,11 +451,12 @@ struct bpf_insn_aux_data {
 	u8 alu_state; /* used in combination with alu_limit */
 
 	/* below fields are initialized once */
-	unsigned int orig_idx; /* original instruction index */
 	bool prune_point;
 	bool jmp_point;
 };
 
+#define ORIG_IDX_BY_OFF(head, off)	(off)
+
 #define MAX_USED_MAPS 64 /* max number of maps accessed by one eBPF program */
 #define MAX_USED_BTFS 64 /* max number of BTFs accessed by one BPF program */
 
diff --git a/kernel/bpf/verifier.c b/kernel/bpf/verifier.c
index d517d13878cf..e2545cd128d8 100644
--- a/kernel/bpf/verifier.c
+++ b/kernel/bpf/verifier.c
@@ -15428,7 +15428,7 @@ static struct bpf_prog *bpf_patch_insn_data(struct bpf_verifier_env *env, u32 of
 		if (PTR_ERR(new_prog) == -ERANGE)
 			verbose(env,
 				"insn %d cannot be patched due to 16-bit range\n",
-				env->insn_aux_data[off].orig_idx);
+				ORIG_IDX_BY_OFF(env->insn_aux_data, off));
 		vfree(new_data);
 		return NULL;
 	}
@@ -17652,7 +17652,7 @@ int bpf_check(struct bpf_prog **prog, union bpf_attr *attr, bpfptr_t uattr)
 	u64 start_time = ktime_get_ns();
 	struct bpf_verifier_env *env;
 	struct bpf_verifier_log *log;
-	int i, len, ret = -EINVAL;
+	int len, ret = -EINVAL;
 	bool is_priv;
 
 	/* no program is valid */
@@ -17673,8 +17673,6 @@ int bpf_check(struct bpf_prog **prog, union bpf_attr *attr, bpfptr_t uattr)
 	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];
 	env->fd_array = make_bpfptr(attr->fd_array, uattr.is_kernel);
-- 
2.20.1