Re: [PATCH v2 1/5] objtool: Deal with relative jump tables correctly

[Josh Poimboeuf]

On Thu, Oct 10, 2024 at 04:07:45PM +0200, Peter Zijlstra wrote:
> On Thu, Oct 10, 2024 at 03:59:43PM +0200, Ard Biesheuvel wrote:
> > On Thu, 10 Oct 2024 at 15:26, Peter Zijlstra <peterz@xxxxxxxxxxxxx> wrote:
> > >
> > > On Thu, Oct 10, 2024 at 02:28:03PM +0200, Ard Biesheuvel wrote:
> > > > diff --git a/tools/objtool/check.c b/tools/objtool/check.c
> > > > index 3cb3e9b5ad0b..7f7981a93535 100644
> > > > --- a/tools/objtool/check.c
> > > > +++ b/tools/objtool/check.c
> > > > @@ -2101,6 +2101,8 @@ static int add_jump_table(struct objtool_file *file, struct instruction *insn,
> > > >  {
> > > >       struct symbol *pfunc = insn_func(insn)->pfunc;
> > > >       struct reloc *table = insn_jump_table(insn);
> > > > +     unsigned int rtype = reloc_type(table);
> > > > +     bool pcrel = rtype == R_X86_64_PC32;
> > >
> > > R_DATA32 or R_TEXT32 please, the budding cross arch stuff has their own
> > > names for all that.
> > >
> > 
> > #define R_DATA32        R_X86_64_PC32
> > #define R_DATA64        R_X86_64_PC32
> > #define R_TEXT32        R_X86_64_PC32
> > #define R_TEXT64        R_X86_64_PC32
> > 
> > Clear as mud.

Yep... :-/

> > 
> > I'd guess we need the '64' variant here, but I'm not sure which one to
> > use for a .rodata relocation pointing to .text. Any hints?

This should be R_TEXT64.

> Josh? do R_{DATA,TEXT}64 want to be _PC64 ?

Actually, R_{DATA,TEXT}32 should be R_386_PC32.

-- 
Josh