On Tue, Apr 16, 2024 at 7:38 AM Alan Maguire <alan.maguire@xxxxxxxxxx> wrote:
>
> Specifying --btf_features=all enables all supported BTF features.
> However there are some features that are non-standard, so we should
> support a way to use them in --btf_features but not participate in
> the set of features enabled by "--btf_features=all". As part of this,
> also support all used in a list of --btf_features, i.e.
>
> --btf_features=all,nonstandard_feature
>
> Signed-off-by: Alan Maguire <alan.maguire@xxxxxxxxxx>
> ---
> man-pages/pahole.1 | 2 +-
> pahole.c | 36 +++++++++++++++++++++++-------------
> 2 files changed, 24 insertions(+), 14 deletions(-)
>
> diff --git a/man-pages/pahole.1 b/man-pages/pahole.1
> index 2be165d..2c08e97 100644
> --- a/man-pages/pahole.1
> +++ b/man-pages/pahole.1
> @@ -290,7 +290,7 @@ Allow using all the BTF features supported by pahole.
>
> .TP
> .B \-\-btf_features=FEATURE_LIST
> -Encode BTF using the specified feature list, or specify 'all' for all features supported. This option can be used as an alternative to unsing multiple BTF-related options. Supported features are
> +Encode BTF using the specified feature list, or specify 'all' for all standard features supported. This option can be used as an alternative to unsing multiple BTF-related options. Supported standard features are
>
> .nf
> encode_force Ignore invalid symbols when encoding BTF; for example
> diff --git a/pahole.c b/pahole.c
> index 77772bb..890ef81 100644
> --- a/pahole.c
> +++ b/pahole.c
> @@ -1266,23 +1266,26 @@ ARGP_PROGRAM_VERSION_HOOK_DEF = dwarves_print_version;
> * BTF encoding apply; we encode type/decl tags, do not encode
> * floats, etc. This ensures backwards compatibility.
> */
> -#define BTF_FEATURE(name, alias, default_value) \
> - { #name, #alias, &conf_load.alias, default_value }
> +#define BTF_FEATURE(name, alias, default_value, enable_for_all) \
> + { #name, #alias, &conf_load.alias, default_value, enable_for_all }
>
> struct btf_feature {
> const char *name;
> const char *option_alias;
> bool *conf_value;
> bool default_value;
> + bool enable_for_all; /* some nonstandard features may not
> + * be enabled for --btf_features=all
> + */
> } btf_features[] = {
> - BTF_FEATURE(encode_force, btf_encode_force, false),
> - BTF_FEATURE(var, skip_encoding_btf_vars, true),
> - BTF_FEATURE(float, btf_gen_floats, false),
> - BTF_FEATURE(decl_tag, skip_encoding_btf_decl_tag, true),
> - BTF_FEATURE(type_tag, skip_encoding_btf_type_tag, true),
> - BTF_FEATURE(enum64, skip_encoding_btf_enum64, true),
> - BTF_FEATURE(optimized_func, btf_gen_optimized, false),
> - BTF_FEATURE(consistent_func, skip_encoding_btf_inconsistent_proto, false),
> + BTF_FEATURE(encode_force, btf_encode_force, false, true),
> + BTF_FEATURE(var, skip_encoding_btf_vars, true, true),
> + BTF_FEATURE(float, btf_gen_floats, false, true),
> + BTF_FEATURE(decl_tag, skip_encoding_btf_decl_tag, true, true),
> + BTF_FEATURE(type_tag, skip_encoding_btf_type_tag, true, true),
> + BTF_FEATURE(enum64, skip_encoding_btf_enum64, true, true),
> + BTF_FEATURE(optimized_func, btf_gen_optimized, false, true),
> + BTF_FEATURE(consistent_func, skip_encoding_btf_inconsistent_proto, false, true),
> };
maybe keep those special features in a separate array instead?
it is kind of weird to see --btf_features=all,and_then_some, maybe it
makes sense to have --btf_extras or something for those?
>
> #define BTF_MAX_FEATURE_STR 1024
> @@ -1350,8 +1353,10 @@ static void parse_btf_features(const char *features, bool strict)
> if (strcmp(features, "all") == 0) {
> int i;
>
> - for (i = 0; i < ARRAY_SIZE(btf_features); i++)
> - enable_btf_feature(&btf_features[i]);
> + for (i = 0; i < ARRAY_SIZE(btf_features); i++) {
> + if (btf_features[i].enable_for_all)
> + enable_btf_feature(&btf_features[i]);
> + }
> return;
> }
>
> @@ -1361,7 +1366,12 @@ static void parse_btf_features(const char *features, bool strict)
> struct btf_feature *feature = find_btf_feature(feature_name);
>
> if (!feature) {
> - if (strict) {
> + /* --btf_features=all,nonstandard_feature should be
> + * allowed.
> + */
> + if (strcmp(feature_name, "all") == 0) {
> + parse_btf_features(feature_name, strict);
> + } else if (strict) {
> fprintf(stderr, "Feature '%s' in '%s' is not supported. Supported BTF features are:\n",
> feature_name, features);
> show_supported_btf_features(stderr);
> --
> 2.39.3
>
>
