Re: [PATCH dwarves v4 1/2] pahole: Add --btf_feature=decl_tag_kfuncs feature

[Alan Maguire <alan.maguire@oracle.com>]

On 06/02/2024 12:47, Jiri Olsa wrote:
> On Sun, Feb 04, 2024 at 11:40:37AM -0700, Daniel Xu wrote:
>> Add a feature flag to guard tagging of kfuncs. The next commit will
>> implement the actual tagging.
>>
>> Signed-off-by: Daniel Xu <dxu@dxuuu.xyz>

Reviewed-by: Alan Maguire <alan.maguire@oracle.com>

Thanks for adding this!

>> ---
>>  btf_encoder.c | 2 ++
>>  dwarves.h     | 1 +
>>  pahole.c      | 1 +
>>  3 files changed, 4 insertions(+)
> 
> we should update man page as well
> 
> also we need to update the kernel's scripts/Makefile.btf with
> the new option for the next pahole version (1.26 I guess)
>

Yep, something like this added to scripts/Makefile.btf
should do it:

pahole-flags-$(call test-ge, $(pahole-ver), 126)       = -j
--lang_exclude=rust
--btf_features=encode_force,var,float,decl_tag,type_tag,enum64,optimized_func,consistent_func,tag_kfuncs

This should hopefully be the last version check we need - we can
just add features to the list as required, and pahole will apply the
ones it knows about. Thanks!

Alan

> jirka
> 
>>
>> diff --git a/btf_encoder.c b/btf_encoder.c
>> index fd04008..e325f66 100644
>> --- a/btf_encoder.c
>> +++ b/btf_encoder.c
>> @@ -77,6 +77,7 @@ struct btf_encoder {
>>  			  verbose,
>>  			  force,
>>  			  gen_floats,
>> +			  tag_kfuncs,
>>  			  is_rel;
>>  	uint32_t	  array_index_id;
>>  	struct {
>> @@ -1642,6 +1643,7 @@ struct btf_encoder *btf_encoder__new(struct cu *cu, const char *detached_filenam
>>  		encoder->force		 = conf_load->btf_encode_force;
>>  		encoder->gen_floats	 = conf_load->btf_gen_floats;
>>  		encoder->skip_encoding_vars = conf_load->skip_encoding_btf_vars;
>> +		encoder->tag_kfuncs	 = conf_load->btf_decl_tag_kfuncs;
>>  		encoder->verbose	 = verbose;
>>  		encoder->has_index_type  = false;
>>  		encoder->need_index_type = false;
>> diff --git a/dwarves.h b/dwarves.h
>> index 857b37c..996eb70 100644
>> --- a/dwarves.h
>> +++ b/dwarves.h
>> @@ -87,6 +87,7 @@ struct conf_load {
>>  	bool			skip_encoding_btf_vars;
>>  	bool			btf_gen_floats;
>>  	bool			btf_encode_force;
>> +	bool			btf_decl_tag_kfuncs;
>>  	uint8_t			hashtable_bits;
>>  	uint8_t			max_hashtable_bits;
>>  	uint16_t		kabi_prefix_len;
>> diff --git a/pahole.c b/pahole.c
>> index 768a2fe..48c19b7 100644
>> --- a/pahole.c
>> +++ b/pahole.c
>> @@ -1278,6 +1278,7 @@ struct btf_feature {
>>  	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(decl_tag_kfuncs, btf_decl_tag_kfuncs, false),
>>  };
>>  
>>  #define BTF_MAX_FEATURE_STR	1024
>> -- 
>> 2.42.1
>>