Em Fri, Sep 18, 2020 at 01:40:57PM -0700, Hao Luo escreveu:
> Introduce an option --btf_encode_symbols to pahole so that pahole
> will only encode global symbols upon request. On the kernel side,
> we can add a Kconfig to turn on this feature. This would make the
> rollout of pahole v1.18 safe against potential bugs in the feature
> introduced in commit f3d9054ba8ff ("btf_encoder: Teach pahole to
> store percpu variables in vmlinux BTF.").
'encode_symbols' is too generic, please rename it to
encode_global_symbols or something like that.
- Arnaldo
> Signed-off-by: Hao Luo <haoluo@xxxxxxxxxx>
> ---
> btf_encoder.c | 5 ++++-
> btf_encoder.h | 2 +-
> pahole.c | 11 ++++++++++-
> 3 files changed, 15 insertions(+), 3 deletions(-)
>
> diff --git a/btf_encoder.c b/btf_encoder.c
> index 982f59d..54ffdd1 100644
> --- a/btf_encoder.c
> +++ b/btf_encoder.c
> @@ -237,7 +237,7 @@ static struct variable *hashaddr__find_variable(const struct hlist_head hashtabl
> return NULL;
> }
>
> -int cu__encode_btf(struct cu *cu, int verbose, bool force)
> +int cu__encode_btf(struct cu *cu, int verbose, bool force, bool encode_symbols)
> {
> bool add_index_type = false;
> uint32_t type_id_off;
> @@ -314,6 +314,9 @@ int cu__encode_btf(struct cu *cu, int verbose, bool force)
> }
> }
>
> + /* if there is no request to encode symbols, just finish. */
> + if (!encode_symbols)
> + goto out;
>
> if (btfe->percpu_shndx == 0 || !btfe->symtab)
> goto out;
> diff --git a/btf_encoder.h b/btf_encoder.h
> index bca2348..f2e95fe 100644
> --- a/btf_encoder.h
> +++ b/btf_encoder.h
> @@ -13,6 +13,6 @@ struct cu;
>
> int btf_encoder__encode();
>
> -int cu__encode_btf(struct cu *cu, int verbose, bool force);
> +int cu__encode_btf(struct cu *cu, int verbose, bool force, bool encode_symbols);
>
> #endif /* _BTF_ENCODER_H_ */
> diff --git a/pahole.c b/pahole.c
> index e1cde61..079d951 100644
> --- a/pahole.c
> +++ b/pahole.c
> @@ -26,6 +26,7 @@
> static bool btf_encode;
> static bool ctf_encode;
> static bool first_obj_only;
> +static bool btf_encode_symbols;
>
> static uint8_t class__include_anonymous;
> static uint8_t class__include_nested_anonymous;
> @@ -809,6 +810,7 @@ ARGP_PROGRAM_VERSION_HOOK_DEF = dwarves_print_version;
> #define ARGP_header_type 314
> #define ARGP_size_bytes 315
> #define ARGP_range 316
> +#define ARGP_btf_encode_symbols 317
>
> static const struct argp_option pahole__options[] = {
> {
> @@ -1087,6 +1089,11 @@ static const struct argp_option pahole__options[] = {
> .key = 'J',
> .doc = "Encode as BTF",
> },
> + {
> + .name = "btf_encode_symbols",
> + .key = ARGP_btf_encode_symbols,
> + .doc = "Encode global symbols in BTF. Off by default."
> + },
> {
> .name = "force",
> .key = 'j',
> @@ -1207,6 +1214,8 @@ static error_t pahole__options_parser(int key, char *arg,
> conf.range = arg; break;
> case ARGP_header_type:
> conf.header_type = arg; break;
> + case ARGP_btf_encode_symbols:
> + btf_encode_symbols = true; break;
> default:
> return ARGP_ERR_UNKNOWN;
> }
> @@ -2352,7 +2361,7 @@ static enum load_steal_kind pahole_stealer(struct cu *cu,
> goto filter_it;
>
> if (btf_encode) {
> - cu__encode_btf(cu, global_verbose, force);
> + cu__encode_btf(cu, global_verbose, force, btf_encode_symbols);
> return LSK__KEEPIT;
> }
>
> --
> 2.28.0.681.g6f77f65b4e-goog
>
--
- Arnaldo
