| Message ID | 20210507054119.270888-5-andrii@kernel.org (mailing list archive) |
|---|---|
| State | RFC |
| Delegated to: | BPF |
| Headers | show |
| Series | BPF static linker: global symbols visibility | expand |
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);
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@mail.gmail.com/T/#m664d4b0d6b31ac8b2669360e0fc2d6962e9f5ec1 Signed-off-by: Andrii Nakryiko <andrii@kernel.org> --- tools/bpf/bpftool/gen.c | 4 ++++ 1 file changed, 4 insertions(+)