From: Eduard Zingerman <eddyz87@gmail.com>
Date: Tue, 10 Dec 2024 04:10:53 +0000 (-0800)
Subject: bpf: add find_containing_subprog() utility function
X-Git-Tag: v6.13-rc3~9^2~7^2~7
X-Git-Url: http://git.ipfire.org/?a=commitdiff_plain;h=27e88bc4df1d80888fe1aaca786a7cc6e69587e2;p=thirdparty%2Flinux.git

bpf: add find_containing_subprog() utility function

Add a utility function, looking for a subprogram containing a given
instruction index, rewrite find_subprog() to use this function.

Signed-off-by: Eduard Zingerman <eddyz87@gmail.com>
Link: https://lore.kernel.org/r/20241210041100.1898468-2-eddyz87@gmail.com
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
---

diff --git a/kernel/bpf/verifier.c b/kernel/bpf/verifier.c
index 01fbef9576e00..277c1892bb9a8 100644
--- a/kernel/bpf/verifier.c
+++ b/kernel/bpf/verifier.c
@@ -2597,16 +2597,36 @@ static int cmp_subprogs(const void *a, const void *b)
 	       ((struct bpf_subprog_info *)b)->start;
 }
 
+/* Find subprogram that contains instruction at 'off' */
+static struct bpf_subprog_info *find_containing_subprog(struct bpf_verifier_env *env, int off)
+{
+	struct bpf_subprog_info *vals = env->subprog_info;
+	int l, r, m;
+
+	if (off >= env->prog->len || off < 0 || env->subprog_cnt == 0)
+		return NULL;
+
+	l = 0;
+	r = env->subprog_cnt - 1;
+	while (l < r) {
+		m = l + (r - l + 1) / 2;
+		if (vals[m].start <= off)
+			l = m;
+		else
+			r = m - 1;
+	}
+	return &vals[l];
+}
+
+/* Find subprogram that starts exactly at 'off' */
 static int find_subprog(struct bpf_verifier_env *env, int off)
 {
 	struct bpf_subprog_info *p;
 
-	p = bsearch(&off, env->subprog_info, env->subprog_cnt,
-		    sizeof(env->subprog_info[0]), cmp_subprogs);
-	if (!p)
+	p = find_containing_subprog(env, off);
+	if (!p || p->start != off)
 		return -ENOENT;
 	return p - env->subprog_info;
-
 }
 
 static int add_subprog(struct bpf_verifier_env *env, int off)