On 8/1/22 13:24, Jiri Olsa wrote: > On Sun, Jul 31, 2022 at 05:26:49PM -0600, James Hilliard wrote: >> The GNU assembler generates an empty .bss section. This is a well >> established behavior in GAS that happens in all supported targets. >> >> The LLVM assembler doesn't generate an empty .bss section. >> >> bpftool chokes on the empty .bss section. >> >> Additionally in bpf_object__elf_collect the sec_desc->data is not >> initialized when a section is not recognized. In this case, this >> happens with .comment. >> >> So we must check that sec_desc->data is initialized before checking >> if the size is 0. > > oops David send same change but I asked him to move the check > to bpf_object__elf_collect [1] .. but with your explanation this > fix actualy looks fine to me FWIW, I only just got back to actually making that change. This patch has a much better explanation than the one I sent so +1 from me also David > > jirka > > > [1] https://lore.kernel.org/bpf/YuKaFiZ+ksB5f0Ye@krava/ > >> >> Signed-off-by: James Hilliard <james.hilliard1@xxxxxxxxx> >> Cc: Jose E. Marchesi <jose.marchesi@xxxxxxxxxx> >> --- >> tools/lib/bpf/libbpf.c | 4 ++++ >> 1 file changed, 4 insertions(+) >> >> diff --git a/tools/lib/bpf/libbpf.c b/tools/lib/bpf/libbpf.c >> index 50d41815f431..77e3797cf75a 100644 >> --- a/tools/lib/bpf/libbpf.c >> +++ b/tools/lib/bpf/libbpf.c >> @@ -1642,6 +1642,10 @@ static int bpf_object__init_global_data_maps(struct bpf_object *obj) >> for (sec_idx = 1; sec_idx < obj->efile.sec_cnt; sec_idx++) { >> sec_desc = &obj->efile.secs[sec_idx]; >> >> + /* Skip recognized sections with size 0. */ >> + if (sec_desc->data && sec_desc->data->d_size == 0) >> + continue; >> + >> switch (sec_desc->sec_type) { >> case SEC_DATA: >> sec_name = elf_sec_name(obj, elf_sec_by_idx(obj, sec_idx)); >> -- >> 2.34.1 >>
