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authorAndrii Nakryiko <andrii@kernel.org>2021-05-06 22:41:16 -0700
committerAlexei Starovoitov <ast@kernel.org>2021-05-11 15:07:17 -0700
commit31332ccb756274c185cfd458b68b29a9371dceac (patch)
treea99857c0ae6b765de93e1af75a45f52f3fc4129c /tools/bpf
parent256eab48e70c0eaf5b1b9af83c0588491986c7de (diff)
bpftool: Stop emitting static variables in BPF skeleton
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> Signed-off-by: Alexei Starovoitov <ast@kernel.org> Link: https://lore.kernel.org/bpf/20210507054119.270888-5-andrii@kernel.org
Diffstat (limited to 'tools/bpf')
-rw-r--r--tools/bpf/bpftool/gen.c4
1 files changed, 4 insertions, 0 deletions
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);