Re: [PATCH v4 01/10] objtool: Handle various symbol types of rodata

[Tiezhu Yang]

On 11/28/2024 02:53 AM, Josh Poimboeuf wrote:
> On Wed, Nov 27, 2024 at 02:39:13PM +0800, Tiezhu Yang wrote:
> > On 11/27/2024 08:52 AM, Josh Poimboeuf wrote:
> > > On Tue, Nov 26, 2024 at 06:41:29PM +0800, Tiezhu Yang wrote:
> > > > On 11/26/2024 02:44 PM, Josh Poimboeuf wrote:
> > > > > On Fri, Nov 22, 2024 at 12:49:56PM +0800, Tiezhu Yang wrote:
> > > > > > @@ -2094,12 +2095,19 @@ static int add_jump_table(struct objtool_file *file, struct instruction *insn,
> > > > >
> > > > > 'prev_offset' needs to be updated as well.
> > > >
> > > > I am not sure I understand your comment correctly, I can not see
> > > > what should to do about 'prev_offset'.
> > >
> > > Further down the function there is
> > >
> > >   prev_offset = reloc_offset(reloc);
> > >
> > > which needs to be changed to
> > >
> > >   prev_offset = offset;
> > >
> > > as part of the patch.
> >
> > If I understand correctly, reloc_offset(reloc) is different with
> > reloc->sym->offset + reloc_addend(reloc), tested on x86 and readelf
> > shows that their values are different, reloc_offset(reloc) is the
> > first column of .rela.rodata, reloc->sym->offset is the second to
> > last column of .rela.rodata, reloc_addend(reloc) is the last column
> > of .rela.rodata.
> >
> > If do the above change as you suggested, there will be some objtool
> > warnings on x86. I think it should be:
> >
> >   prev_offset = reloc_offset(reloc);
> >
> > rather than:
> >
> >   prev_offset = offset;
> >
> > That is to say, no need to change "prev_offset".
> > Could you please check it again, please let me know if I am wrong.
>
> Sorry, I was confused by the fact there are two different meanings for
> "offset": one for where the relocation is written, and one for the
> symbol it refers to.
>
> How about instead of 'offset', call it 'sym_offset'?

OK, looks better, will modify it in the next version.