On Mon, Nov 02, 2020 at 10:59:08PM +0100, Jiri Olsa wrote: > On Sat, Oct 31, 2020 at 11:31:31PM +0100, Jiri Olsa wrote: > > We need to generate just single BTF instance for the > > function, while DWARF data contains multiple instances > > of DW_TAG_subprogram tag. > > > > Unfortunately we can no longer rely on DW_AT_declaration > > tag (https://gcc.gnu.org/bugzilla/show_bug.cgi?id=97060) > > > > Instead we apply following checks: > > - argument names are defined for the function > > - there's symbol and address defined for the function > > - function is generated only once > > > > Also because we want to follow kernel's ftrace traceable > > functions, this patchset is adding extra check that the > > function is one of the ftrace's functions. > > > > All ftrace functions addresses are stored in vmlinux > > binary within symbols: > > __start_mcount_loc > > __stop_mcount_loc > > hum, for some reason this does not pass through bpf internal > functions like bpf_iter_bpf_map.. I learned it hard way ;-) > will check so it gets filtered out because it's __init function I'll check if the fix below catches all internal functions, but I guess we should do something more robust jirka --- diff --git a/btf_encoder.c b/btf_encoder.c index 0a378aa92142..3cd94280c35b 100644 --- a/btf_encoder.c +++ b/btf_encoder.c @@ -143,7 +143,8 @@ static int filter_functions(struct btf_elf *btfe, struct mcount_symbols *ms) /* Do not enable .init section functions. */ if (init_filter && func->addr >= ms->init_begin && - func->addr < ms->init_end) + func->addr < ms->init_end && + strncmp("bpf_", func->name, 4)) continue; /* Make sure function is within mcount addresses. */
