Re: [PATCH 02/16] x86/build: Remove RWX sections and align on 4KB

[Evgeniy Baskov]

On 2022-10-19 10:04, Ard Biesheuvel wrote:
> On Tue, 6 Sept 2022 at 12:41, Evgeniy Baskov <baskov@xxxxxxxxx> wrote:
> > Avoid creating sections with maximal privileges to prepare for W^X
>
> privileges
>
> > implementation. Align sections on page size (4KB) to allow protecting
> > them in page table.
>
> in the page tables.
>
> > Signed-off-by: Evgeniy Baskov <baskov@xxxxxxxxx>
> > ---
> >  arch/x86/kernel/vmlinux.lds.S | 15 ++++++++-------
> >  1 file changed, 8 insertions(+), 7 deletions(-)
> >
> > diff --git a/arch/x86/kernel/vmlinux.lds.S 
> > b/arch/x86/kernel/vmlinux.lds.S
> > index 15f29053cec4..6587e0201b50 100644
> > --- a/arch/x86/kernel/vmlinux.lds.S
> > +++ b/arch/x86/kernel/vmlinux.lds.S
> > @@ -102,12 +102,11 @@ jiffies = jiffies_64;
> >  PHDRS {
> >         text PT_LOAD FLAGS(5);          /* R_E */
> >         data PT_LOAD FLAGS(6);          /* RW_ */
> > -#ifdef CONFIG_X86_64
> > -#ifdef CONFIG_SMP
> > +#if defined(CONFIG_X86_64) && defined(CONFIG_SMP)
> >         percpu PT_LOAD FLAGS(6);        /* RW_ */
> >  #endif
> > -       init PT_LOAD FLAGS(7);          /* RWE */
> > -#endif
> > +       inittext PT_LOAD FLAGS(5);      /* R_E */
> > +       init PT_LOAD FLAGS(6);          /* RW_ */
>
> Please explain in the commit log how this change affects X86_32
>
> >         note PT_NOTE FLAGS(0);          /* ___ */
> >  }
> >
> > @@ -226,9 +225,10 @@ SECTIONS
> >  #endif
> >
> >         INIT_TEXT_SECTION(PAGE_SIZE)
> > -#ifdef CONFIG_X86_64
> > -       :init
> > -#endif
> > +       :inittext
> > +
> > +       . = ALIGN(PAGE_SIZE);
> > +
> >
> >         /*
> >          * Section for code used exclusively before alternatives are 
> > run. All
> > @@ -240,6 +240,7 @@ SECTIONS
> >         .altinstr_aux : AT(ADDR(.altinstr_aux) - LOAD_OFFSET) {
> >                 *(.altinstr_aux)
> >         }
> > +       :init
> >
> >         INIT_DATA_SECTION(16)
> >
> > --
> > 2.35.1

Thanks for pointing you, I'll fix all mentioned nitpicks before sending
this again.