Re: [PATCH v2 01/24] x86/xen: Mark cpu_bringup_and_idle() as dead_end_function

[Juergen Gross]

On 30.08.21 09:48, Peter Zijlstra wrote:
> On Mon, Aug 30, 2021 at 07:55:02AM +0200, Juergen Gross wrote:
> > > > From: Josh Poimboeuf <jpoimboe@xxxxxxxxxx>
> > > > Subject: [PATCH] x86/xen: Move hypercall_page to top of the file
> > > >
> > > > Because hypercall_page is page-aligned, the assembler inexplicably adds
> > > > an unreachable jump from after the end of the previous code to the
> > > > beginning of hypercall_page.
> > > >
> > > > That confuses objtool, understandably.  It also creates significant text
> > > > fragmentation.  As a result, much of the object file is wasted text
> > > > (nops).
> > > >
> > > > Move hypercall_page to the beginning of the file to both prevent the
> > > > text fragmentation and avoid the dead jump instruction.
> > > >
> > > > $ size /tmp/head_64.before.o /tmp/head_64.after.o
> > > >      text       data        bss        dec        hex    filename
> > > >     10924     307252       4096     322272      4eae0
> > > > /tmp/head_64.before.o
> > > >      6823     307252       4096     318171      4dadb
> > > > /tmp/head_64.after.o
> > > >
> > > > Signed-off-by: Josh Poimboeuf <jpoimboe@xxxxxxxxxx
> > >
> > > Reviewed-by: Juergen Gross <jgross@xxxxxxxx>
> >
> > Umm, will this be carried through the tip tree, or shall I take it in
> > the xen tree?
>
> I have it in the whole x86/objtool/paravirt series. I you want it in the
> Xen tree, I'll be happy to drop it from there, although I hope to get
> all that merged this cycles somewhere.

Okay, I think it is better kept in your series then.


Juergen

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