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, 1 insertions, 1 deletions

diff --git a/tools/testing/selftests/bpf/progs/test_snprintf_single.c b/tools/testing/selftests/bpf/progs/test_snprintf_single.c
index 402adaf344f9..3095837334d3 100644
--- a/tools/testing/selftests/bpf/progs/test_snprintf_single.c
+++ b/tools/testing/selftests/bpf/progs/test_snprintf_single.c
@@ -5,7 +5,7 @@
 #include <bpf/bpf_helpers.h>
 
 /* The format string is filled from the userspace such that loading fails */
-static const char fmt[10];
+const char fmt[10];
 
 SEC("raw_tp/sys_enter")
 int handler(const void *ctx)