From: Yonghong Song yhs@fb.com
mainline inclusion from mainline-5.17-rc1 commit 69a055d546156adc6f7727ec981f721d5ba9231a category: feature bugzilla: https://gitee.com/openeuler/kernel/issues/I5EUVD CVE: NA
Reference: https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/commit/?i...
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Commit 2dc1e488e5cd ("libbpf: Support BTF_KIND_TYPE_TAG") added the BTF_KIND_TYPE_TAG support. But to test vmlinux build with ...
#define __user __attribute__((btf_type_tag("user")))
... I needed to sync libbpf repo and manually copy libbpf sources to pahole. To simplify process, I used BTF_KIND_RESTRICT to simulate the BTF_KIND_TYPE_TAG with vmlinux build as "restrict" modifier is barely used in kernel.
But this approach missed one case in dedup with structures where BTF_KIND_RESTRICT is handled and BTF_KIND_TYPE_TAG is not handled in btf_dedup_is_equiv(), and this will result in a pahole dedup failure. This patch fixed this issue and a selftest is added in the subsequent patch to test this scenario.
The other missed handling is in btf__resolve_size(). Currently the compiler always emit like PTR->TYPE_TAG->... so in practice we don't hit the missing BTF_KIND_TYPE_TAG handling issue with compiler generated code. But lets add case BTF_KIND_TYPE_TAG in the switch statement to be future proof.
Fixes: 2dc1e488e5cd ("libbpf: Support BTF_KIND_TYPE_TAG") Signed-off-by: Yonghong Song yhs@fb.com Signed-off-by: Daniel Borkmann daniel@iogearbox.net Link: https://lore.kernel.org/bpf/20211115163937.3922235-1-yhs@fb.com (cherry picked from commit 69a055d546156adc6f7727ec981f721d5ba9231a) Signed-off-by: Wang Yufen wangyufen@huawei.com --- tools/lib/bpf/btf.c | 2 ++ 1 file changed, 2 insertions(+)
diff --git a/tools/lib/bpf/btf.c b/tools/lib/bpf/btf.c index 5a55c473c3d6..98eaca3d461c 100644 --- a/tools/lib/bpf/btf.c +++ b/tools/lib/bpf/btf.c @@ -605,6 +605,7 @@ __s64 btf__resolve_size(const struct btf *btf, __u32 type_id) case BTF_KIND_RESTRICT: case BTF_KIND_VAR: case BTF_KIND_DECL_TAG: + case BTF_KIND_TYPE_TAG: type_id = t->type; break; case BTF_KIND_ARRAY: @@ -4007,6 +4008,7 @@ static int btf_dedup_is_equiv(struct btf_dedup *d, __u32 cand_id, case BTF_KIND_PTR: case BTF_KIND_TYPEDEF: case BTF_KIND_FUNC: + case BTF_KIND_TYPE_TAG: if (cand_type->info != canon_type->info) return 0; return btf_dedup_is_equiv(d, cand_type->type, canon_type->type);