Re: [PATCH v5 02/10] objtool: Handle different entry size of rodata

[Tiezhu Yang]

On 12/10/2024 03:54 AM, Josh Poimboeuf wrote:
> On Sat, Dec 07, 2024 at 09:59:07AM +0800, Tiezhu Yang wrote:
> > +__weak unsigned int arch_reloc_size(struct reloc *reloc)
> > +{
> > +	return 8;
> > +}
>
> Instead of making a weak function, each arch should have an explicit
> definition of this function, as it's not always 8:
>
> - x86 has R_X86_64_PC32 and R_X86_64_PLT32 which are 4 bytes.
>
> - 32-bit powerpc
>
> - 64-bit powerpc has R_PPC64_REL32

For x86, like this, I am not sure "case R_X86_64_32" is necessary,
leave it as is if no objections, please let me know if it should be
removed.

unsigned int arch_reloc_size(struct reloc *reloc)
{
        switch (reloc_type(reloc)) {
        case R_X86_64_32:
        case R_X86_64_PC32:
        case R_X86_64_PLT32:
                return 4;
        default:
                return 8;
        }
}

For ppc, like this:

unsigned int arch_reloc_size(struct reloc *reloc)
{
        switch (reloc_type(reloc)) {
        case R_PPC_REL32:
        case R_PPC64_REL32:
                return 4;
        default:
                return 8;
        }
}

> > @@ -1967,8 +1973,10 @@ static int add_jump_table(struct objtool_file *file, struct instruction *insn,
> >  		if (reloc != table && reloc == next_table)
> >  			break;
> >
> > +		entry_size = arch_reloc_size(reloc);
> > +
> >  		/* Make sure the table entries are consecutive: */
> > -		if (prev_offset && reloc_offset(reloc) != prev_offset + 8)
> > +		if (prev_offset && reloc_offset(reloc) != prev_offset + entry_size)
> >  			break;
>
> No need to use a variable here, just call arch_reloc_size() directly.

OK, will do it.

Thanks,
Tiezhu