Em Fri, Nov 13, 2020 at 04:12:22PM +0100, Jiri Olsa escreveu:
> Current conditions for picking up function records break
> BTF data on some gcc versions.
>
> Some function records can appear with no arguments but with
> declaration tag set, so moving the 'fn->declaration' in front
> of other checks.
>
> Then checking if argument names are present and finally checking
> ftrace filter if it's present. If ftrace filter is not available,
> using the external tag to filter out non external functions.
Humm has_arg_names() will return true for a:
void foo(void)
function, which I think is right, but can't this function appear
multiple times in different CUs and we end up with the same function
multiple times in the BTF info?
- Arnaldo
> Signed-off-by: Jiri Olsa <jolsa@xxxxxxxxxx>
> ---
> btf_encoder.c | 24 ++++++++++--------------
> 1 file changed, 10 insertions(+), 14 deletions(-)
>
> diff --git a/btf_encoder.c b/btf_encoder.c
> index d531651b1e9e..de471bc754b1 100644
> --- a/btf_encoder.c
> +++ b/btf_encoder.c
> @@ -612,25 +612,21 @@ int cu__encode_btf(struct cu *cu, int verbose, bool force,
> const char *name;
>
> /*
> - * The functions_cnt != 0 means we parsed all necessary
> - * kernel symbols and we are using ftrace location filter
> - * for functions. If it's not available keep the current
> - * dwarf declaration check.
> + * Skip functions that:
> + * - are marked as declarations
> + * - do not have full argument names
> + * - are not in ftrace list (if it's available)
> + * - are not external (in case ftrace filter is not available)
> */
> + if (fn->declaration)
> + continue;
> + if (!has_arg_names(cu, &fn->proto))
> + continue;
> if (functions_cnt) {
> - /*
> - * We check following conditions:
> - * - argument names are defined
> - * - there's symbol and address defined for the function
> - * - function address belongs to ftrace locations
> - * - function is generated only once
> - */
> - if (!has_arg_names(cu, &fn->proto))
> - continue;
> if (!should_generate_function(btfe, function__name(fn, cu)))
> continue;
> } else {
> - if (fn->declaration || !fn->external)
> + if (!fn->external)
> continue;
> }
>
> --
> 2.26.2
>
--
- Arnaldo
