Re: [PATCH dwarves] btf_encoder: fix reversed condition for matching ELF section

On Fri, Oct 04, 2024 at 05:01:46PM -0700, Stephen Brennan wrote:
> We only want to consider PROGBITS and NOBITS. However, when refactoring
> this function for clarity, I managed to miss flip this condition. The
> result is fewer variables output, and bad section names used for the
> ones that are emitted.
> 
> Fixes: bf2eedb ("btf_encoder: Stop indexing symbols for VARs")
> 
> Signed-off-by: Stephen Brennan <[email protected]>
> ---
> 
> Hi Arnaldo,
> 
> This clearly slipped by me in my last small edit based on Alan's feedback, and I
> didn't run a full enough validation test after the last tweak since it was "just
> some small nits".
> 
> (His code review suggestion was not buggy... I introduced it as I shoddily
> redid his suggestion).
> 
> Sorry for the bug introduced at the last second - feel free to fold this into
> the commit or keep the commit as a monument to the bug :)

Nope, as it was just in the next branch, I folded it into the fixed
commit and kept just a lore link to this fixup, all is back in next now
and I'm redoing tests here.

Thanks for realizing the mistake and providing a fix, and thanks to Jiri
and Alan for reviewing the fix.

- Arnaldo
 
> Thanks,
> Stephen
> 
>  btf_encoder.c | 4 ++--
>  1 file changed, 2 insertions(+), 2 deletions(-)
> 
> diff --git a/btf_encoder.c b/btf_encoder.c
> index 201a48c..5954238 100644
> --- a/btf_encoder.c
> +++ b/btf_encoder.c
> @@ -2137,8 +2137,8 @@ static size_t get_elf_section(struct btf_encoder *encoder, uint64_t addr)
>  	/* Start at index 1 to ignore initial SHT_NULL section */
>  	for (size_t i = 1; i < encoder->seccnt; i++) {
>  		/* Variables are only present in PROGBITS or NOBITS (.bss) */
> -		if (encoder->secinfo[i].type == SHT_PROGBITS ||
> -		    encoder->secinfo[i].type == SHT_NOBITS)
> +		if (!(encoder->secinfo[i].type == SHT_PROGBITS ||
> +		     encoder->secinfo[i].type == SHT_NOBITS))
>  			continue;
>  
>  		if (encoder->secinfo[i].addr <= addr &&
> -- 
> 2.43.5