From: Andrii Nakryiko Date: Thu, 7 Apr 2022 23:04:46 +0000 (-0700) Subject: libbpf: Allow WEAK and GLOBAL bindings during BTF fixup X-Git-Url: http://git.maquefel.me/?a=commitdiff_plain;h=3a06ec0a996dc8c4bc518f0b6bedc3587dd15169;p=linux.git 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 --- diff --git a/tools/lib/bpf/libbpf.c b/tools/lib/bpf/libbpf.c index 016ecdd1c3e1a..9deb1fc67f190 100644 --- a/tools/lib/bpf/libbpf.c +++ b/tools/lib/bpf/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);