Messages in this thread | | | Date | Fri, 13 Nov 2015 02:15:54 -0500 | From | Jessica Yu <> | Subject | Re: livepatch: reuse module loader code to write relocations |
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+++ Josh Poimboeuf [12/11/15 14:32 -0600]: >On Thu, Nov 12, 2015 at 03:22:44PM -0500, Jessica Yu wrote: >> Looking into this more, I think we do need one __klp_rela section per >> function being patched. Each rela section is linked to the section to >> which the relocations apply via the rela section's sh_info field. In >> SHT_RELA sections, the sh_info field contains the section index to >> which the relocs apply. We cannot have one single combined rela >> section per object as the call to apply_relocate_add() simply won't >> work, because we would have relocs that apply to different functions >> (and hence different sections). >> >> So I guess instead of a single field in klp_object specifying the >> __klp_rela section index, we could probably just have an array of >> section indices. > >Ok, makes sense, sounds like we need multiple klp relas per object. > >I still don't quite understand the benefit of caching the klp_rela >section indices. What problem does it solve? It seems simpler to just >iterate over all the sections in klp_write_object_relocations().
I was trying to accomodate Miroslav's dislike of klp_reloc_sec :-) But now that we are sure that we need multiple __klp_rela sections per object, I think an array of indices might still be somewhat complicated (we need to figure out its size and everything, a list here would be easier). I think it might be fine to leave things the way they are here.
Jessica
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