Re: [PATCH v3 bpf-next 09/11] bpftool: Add ability to dump LOC_PARAM, LOC_PROTO and LOCSEC

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

On 16/09/2026 23:07, Jiri Olsa wrote:
> 
> On Wed, Sep 16, 2026 at 08:41:16AM +0100, Alan Maguire wrote:
>> In raw mode ensure we can dump new BTF kinds in normal/json format.
>> BTF_KIND_LOC_PARAMs are rendered as strings, for example a
>> const value of 0x2a and a dereference of r10 + 0x20:
>> 
>>   [12] LOC_PARAM '(anon)' size=4 flags=0x2 vlen=1 values='0x2a'
>>   [13] LOC_PARAM '(anon)' size=8 flags=0x38 vlen=2 values='*(r10 + 0x20)'
>> 
>> LOC_PROTOs render the associated values of each of their
>> LOC_PARAMs for easier readability:
>> 
>>   [14] LOC_PROTO '(anon)' vlen=2
>>   	type_id=12 value='r1'
>>   	type_id=13 value='*(r2 + 0x10)'
> 
> nit, AFAICT these are dwarf's registers numbers? could we output arch's register names?
>

thanks for taking a look Jiri! You're right they are DWARF register numbers alright;
the problem is to render them as arch register names we'd need to maintain per-arch
tables in bpftool, which seems like the wrong place to host those. I'd suggest instead
we augment pfunct [1] to support this; it already has an option to display inline expansions
from DWARF, so having a BTF-based expansion of inline sites there seems like it would
be a more natural fit, what do you think? Thanks!

Alan

[1] https://github.com/acmel/dwarves/blob/master/man-pages/pfunct.1

 
> jirka
>