From 075c96c298d40f84feb57dff284563e03e0a5542 Mon Sep 17 00:00:00 2001 From: Andrii Nakryiko Date: Thu, 7 Apr 2022 16:04:46 -0700 Subject: [PATCH] libbpf: Allow WEAK and GLOBAL bindings during BTF fixup During BTF fix up for global variables, global variable can be global weak and will have STB_WEAK binding in ELF. Support such global variables in addition to non-weak ones. This is not the problem when using BPF static linking, as BPF static linker "fixes up" BTF during generation so that libbpf doesn't have to do it anymore during bpf_object__open(), which led to this not being noticed for a while, along with a pretty rare (currently) use of __weak variables and maps. Reported-by: Hengqi Chen Signed-off-by: Andrii Nakryiko Signed-off-by: Alexei Starovoitov Link: https://lore.kernel.org/bpf/20220407230446.3980075-2-andrii@kernel.org --- src/libbpf.c | 7 +++++-- 1 file changed, 5 insertions(+), 2 deletions(-) diff --git a/src/libbpf.c b/src/libbpf.c index 016ecdd..9deb1fc 100644 --- a/src/libbpf.c +++ b/src/libbpf.c @@ -1401,8 +1401,11 @@ static int find_elf_var_offset(const struct bpf_object *obj, const char *name, _ for (si = 0; si < symbols->d_size / sizeof(Elf64_Sym); si++) { Elf64_Sym *sym = elf_sym_by_idx(obj, si); - if (ELF64_ST_BIND(sym->st_info) != STB_GLOBAL || - ELF64_ST_TYPE(sym->st_info) != STT_OBJECT) + if (ELF64_ST_TYPE(sym->st_info) != STT_OBJECT) + continue; + + if (ELF64_ST_BIND(sym->st_info) != STB_GLOBAL && + ELF64_ST_BIND(sym->st_info) != STB_WEAK) continue; sname = elf_sym_str(obj, sym->st_name);