Re: [Xen-devel] [PATCH] xen: arm: include .text.cold and .text.unlikely in text area

[Ian Campbell <Ian.Campbell@xxxxxxxxxx>]

On Tue, 2014-06-10 at 09:50 +0100, Jan Beulich wrote:
> >>> On 09.06.14 at 16:28, <ian.campbell@xxxxxxxxxx> wrote:
> > Otherwise functions in these sections can end up between .text and .rodata
> > which is after _etext and therefore gets made non-executable.
> > 
> > This matches x86 (although it was done there for different reasons).
> > 
> > Signed-off-by: Ian Campbell <ian.campbell@xxxxxxxxxx>
> > Cc: Jan Beulich <JBeulich@xxxxxxxx>
> > ---
> > Jan, any reason why x86 doesn't just use .text.*?
> 
> Because we want the .cold and .unlikely all adjacent, rather than
> intermixed with eventual other ones (imagine mixing in a
> hypothetical .text.hot).

That makes sense. Could we specify .text.* after those as a fallback or
would we rather deal with each new section specifically so we can have a
think about the right location?

I don't suppose there is a linker option to make it barf on
non-explicitly placed sections, is there? That would have turned this
silent (and hard to diagnose) failure into something more explicit.

Ian.

> 
> Jan
> 
> > ---
> >  xen/arch/arm/xen.lds.S |    2 ++
> >  1 file changed, 2 insertions(+)
> > 
> > diff --git a/xen/arch/arm/xen.lds.S b/xen/arch/arm/xen.lds.S
> > index e8b4f47..be55dad 100644
> > --- a/xen/arch/arm/xen.lds.S
> > +++ b/xen/arch/arm/xen.lds.S
> > @@ -30,6 +30,8 @@ SECTIONS
> >    .text : /* XXX should be AT ( XEN_PHYS_START ) */ {
> >          _stext = .;            /* Text section */
> >         *(.text)
> > +       *(.text.cold)
> > +       *(.text.unlikely)
> >         *(.fixup)
> >         *(.gnu.warning)
> >         _etext = .;             /* End of text section */
> > -- 
> > 1.7.10.4
> 
> 
> 



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