Re: [PATCH] module: set __jump_table alignment to 8

[David Daney]

On 03/02/2017 10:26 AM, Jessica Yu wrote:
> +++ Steven Rostedt [02/03/17 13:11 -0500]:
> > Can I get an Ack from a module maintainer?
>
> Acked-by: Jessica Yu <jeyu@xxxxxxxxxx>
>
> Thanks!
>
> Jessica

Thanks Jessica,

Can you also add scripts/module-common.lds to MAINTAINERS so that 
get_maintainers.pl will indicate that Jessica Yu and Rusty Russell be 
CCed on things like this in the future?


> > On Wed,  1 Mar 2017 14:04:53 -0800
> > David Daney <david.daney@xxxxxxxxxx> wrote:
> >
> > > For powerpc the __jump_table section in modules is not aligned, this
> > > causes a WARN_ON() splat when loading a module containing a
> > > __jump_table.
> > >
> > > Strict alignment became necessary with commit 3821fd35b58d
> > > ("jump_label: Reduce the size of struct static_key"), currently in
> > > linux-next, which uses the two least significant bits of pointers to
> > > __jump_table elements.
> > >
> > > Fix by forcing __jump_table to 8, which is the same alignment used for
> > > this section in the kernel proper.
> > >
> > > Signed-off-by: David Daney <david.daney@xxxxxxxxxx>
> > > Tested-by: Sachin Sant <sachinp@xxxxxxxxxxxxxxxxxx>
> > > ---
> > >  scripts/module-common.lds | 2 ++
> > >  1 file changed, 2 insertions(+)
> > >
> > > diff --git a/scripts/module-common.lds b/scripts/module-common.lds
> > > index 73a2c7d..53234e8 100644
> > > --- a/scripts/module-common.lds
> > > +++ b/scripts/module-common.lds
> > > @@ -19,4 +19,6 @@ SECTIONS {
> > >
> > >      . = ALIGN(8);
> > >      .init_array        0 : { *(SORT(.init_array.*)) *(.init_array) }
> > > +
> > > +    __jump_table        0 : ALIGN(8) { KEEP(*(__jump_table)) }
> > >  }