Re: [RFC PATCH 2/9] btf_encoder: store,use section-relative addresses in ELF function representation

[Eduard Zingerman <eddyz87@gmail.com>]

On Thu, 2024-11-28 at 01:23 +0000, Ihor Solodrai wrote:
> From: Alan Maguire <alan.maguire@oracle.com>
> 
> This will help us do more accurate DWARF/ELF matching.

It would be good to have a more detailed explanation here.
E.g. number of generated functions differs with this patch:

# without this patch
$ bpftool btf dump file /home/eddy/work/tmp/old.btf | grep "\] FUNC '" | wc -l
48056
# with this patch
$ bpftool btf dump file /home/eddy/work/tmp/new.btf | grep "\] FUNC '" | wc -l
48189

It would be helpful to peek one of newly added functions and explain
why it was previously excluded.

> 
> Signed-off-by: Alan Maguire <alan.maguire@oracle.com>
> Signed-off-by: Ihor Solodrai <ihor.solodrai@pm.me>
> ---
>  btf_encoder.c | 37 +++++++++++++++++++++++++++++++------
>  1 file changed, 31 insertions(+), 6 deletions(-)
> 
> diff --git a/btf_encoder.c b/btf_encoder.c
> index 98e4d7d..01d7094 100644
> --- a/btf_encoder.c
> +++ b/btf_encoder.c
> @@ -88,6 +88,7 @@ struct btf_encoder_func_state {
>  struct elf_function {
>  	const char	*name;
>  	char		*alias;
> +	uint32_t	addr;
>  	size_t		prefixlen;
>  	struct btf_encoder_func_state state;
>  };
> @@ -131,6 +132,7 @@ struct btf_encoder {
>  		int		    allocated;
>  		int		    cnt;
>  		int		    suffix_cnt; /* number of .isra, .part etc */
> +		uint64_t	    base_addr;

This field is set, but never read.

>  	} functions;
>  };
>  

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