As discussed in [0], stop emitting static variables in BPF skeletons to avoid
issues with name-conflicting static variables across multiple
statically-linked BPF object files.
Users using static variables to pass data between BPF programs and user-space
should do a trivial one-time switch according to the following simple rules:
- read-only `static volatile const` variables should be converted to
`volatile const`;
- read/write `static volatile` variables should just drop `static volatile`
modifiers to become global variables/symbols. To better handle older Clang
versions, such newly converted global variables should be explicitly
initialized with a specific value or `= 0`/`= {}`, whichever is
appropriate.
[0] https://lore.kernel.org/bpf/CAEf4BzZo7_r-hsNvJt3w3kyrmmBJj7ghGY8+k4nvKF0KLjma=w@xxxxxxxxxxxxxx/T/#m664d4b0d6b31ac8b2669360e0fc2d6962e9f5ec1
Signed-off-by: Andrii Nakryiko <andrii@xxxxxxxxxx>
---
tools/bpf/bpftool/gen.c | 4 ++++
1 file changed, 4 insertions(+)
diff --git a/tools/bpf/bpftool/gen.c b/tools/bpf/bpftool/gen.c
index 06fee4a2910a..27dceaf66ecb 100644
--- a/tools/bpf/bpftool/gen.c
+++ b/tools/bpf/bpftool/gen.c
@@ -131,6 +131,10 @@ static int codegen_datasec_def(struct bpf_object *obj,
int need_off = sec_var->offset, align_off, align;
__u32 var_type_id = var->type;
+ /* static variables are not exposed through BPF skeleton */
+ if (btf_var(var)->linkage == BTF_VAR_STATIC)
+ continue;
+
if (off > need_off) {
p_err("Something is wrong for %s's variable #%d: need offset %d, already at %d.\n",
sec_name, i, need_off, off);
--
2.30.2
