Re: [PATCH 1/2] x86: consider effective protection attributes in W+X check

[Thomas Gleixner]

On Thu, 14 Dec 2017, Juergen Gross wrote:
> On 12/12/17 11:31, Jan Beulich wrote:
> >     for (i = 0; i < PTRS_PER_PMD; i++) {
> >             st->current_address = normalize_addr(P + i * PMD_LEVEL_MULT);
> >             if (!pmd_none(*start)) {
> > +                   prot = pmd_flags(*start);
> > +                   eff = effective_prot(eff_in, prot);
> >                     if (pmd_large(*start) || !pmd_present(*start)) {
> > -                           prot = pmd_flags(*start);
> > -                           note_page(m, st, __pgprot(prot), 4);
> > +                           note_page(m, st, __pgprot(prot), eff, 4);
> >                     } else if (!kasan_page_table(m, st, pmd_start)) {
> > -                           walk_pte_level(m, st, *start,
> > +                           walk_pte_level(m, st, *start, eff,
> >                                            P + i * PMD_LEVEL_MULT);
> >                     }
> 
> You can drop the braces for both cases. Applies to similar
> constructs below, too.

No. See: https://marc.info/?l=linux-kernel&m=148467980905537

This is the same issue:

        if (foo)
                bla();
        else
                blurb(somestuff, morestuff, evenmorestuff,
                      crap);
vs.

        if (foo) {
                bla();
        } else {
                blurb(somestuff, morestuff, evenmorestuff,
                      crap);
        }

Thanks,

        tglx