From: Martin KaFai Lau <kafai@fb.com>
Date: Fri, 5 Nov 2021 18:40:20 -0700
Subject: bpf: selftest: Trigger a DCE on the whole subprog
Patch-mainline: v5.16-rc1
Git-commit: d99341b373215cf32bfb7f341fb3e720e0e791ef
References: jsc#PED-1377
This patch adds a test to trigger the DCE to remove
the whole subprog to ensure the verifier does not
depend on a stable subprog index. The DCE is done
by testing a global const.
Signed-off-by: Martin KaFai Lau <kafai@fb.com>
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Link: https://lore.kernel.org/bpf/20211106014020.651638-1-kafai@fb.com
Acked-by: Shung-Hsi Yu <shung-hsi.yu@suse.com>
---
tools/testing/selftests/bpf/progs/for_each_array_map_elem.c | 12 ++++++++++++
1 file changed, 12 insertions(+)
--- a/tools/testing/selftests/bpf/progs/for_each_array_map_elem.c
+++ b/tools/testing/selftests/bpf/progs/for_each_array_map_elem.c
@@ -23,6 +23,16 @@ struct callback_ctx {
int output;
};
+const volatile int bypass_unused = 1;
+
+static __u64
+unused_subprog(struct bpf_map *map, __u32 *key, __u64 *val,
+ struct callback_ctx *data)
+{
+ data->output = 0;
+ return 1;
+}
+
static __u64
check_array_elem(struct bpf_map *map, __u32 *key, __u64 *val,
struct callback_ctx *data)
@@ -54,6 +64,8 @@ int test_pkt_access(struct __sk_buff *sk
data.output = 0;
bpf_for_each_map_elem(&arraymap, check_array_elem, &data, 0);
+ if (!bypass_unused)
+ bpf_for_each_map_elem(&arraymap, unused_subprog, &data, 0);
arraymap_output = data.output;
bpf_for_each_map_elem(&percpu_map, check_percpu_elem, (void *)0, 0);