selftests/bpf: Stop using static variables for passing data to/from user-space

In preparation of skipping emitting static variables in BPF skeletons, switch
all current selftests uses of static variables to pass data between BPF and
user-space to use global variables.

All non-read-only `static volatile` variables become just plain global
variables by dropping `static volatile` part.

Read-only `static volatile const` variables, though, still require `volatile`
modifier, otherwise compiler will ignore whatever values are set from
user-space.

Few static linker tests are using name-conflicting static variables to
validate that static linker still properly handles static variables and
doesn't trip up on name conflicts.

Signed-off-by: Andrii Nakryiko <andrii@kernel.org>
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Link: https://lore.kernel.org/bpf/20210507054119.270888-4-andrii@kernel.org

1 files changed, 2 insertions, 2 deletions

diff --git a/tools/testing/selftests/bpf/progs/bpf_iter_test_kern4.c b/tools/testing/selftests/bpf/progs/bpf_iter_test_kern4.c
index ee49493dc125..400fdf8d6233 100644
--- a/tools/testing/selftests/bpf/progs/bpf_iter_test_kern4.c
+++ b/tools/testing/selftests/bpf/progs/bpf_iter_test_kern4.c
@@ -9,8 +9,8 @@ __u32 map1_id = 0, map2_id = 0;
 __u32 map1_accessed = 0, map2_accessed = 0;
 __u64 map1_seqnum = 0, map2_seqnum1 = 0, map2_seqnum2 = 0;
 
-static volatile const __u32 print_len;
-static volatile const __u32 ret1;
+volatile const __u32 print_len;
+volatile const __u32 ret1;
 
 SEC("iter/bpf_map")
 int dump_bpf_map(struct bpf_iter__bpf_map *ctx)