Re: [Xen-devel] [PATCH v3 1/3] xen/x86: replace '||' usage in the linker script

[Daniel Kiper <daniel.kiper@xxxxxxxxxx>]

On Thu, Jul 12, 2018 at 05:26:49PM +0200, Roger Pau Monné wrote:
> On Thu, Jul 12, 2018 at 01:38:21PM +0200, Daniel Kiper wrote:
> > On Wed, Jul 11, 2018 at 05:34:48PM +0200, Roger Pau Monne wrote:
> > > With '|'. The result is the same, and the later works with lld. Fixes
> > > the following error when building Xen with lld:
> > >
> > > ld    -melf_x86_64_fbsd  -T xen.lds -N prelink.o --build-id=sha1 \
> > >     /root/src/xen/xen/common/symbols-dummy.o -o 
> > > /root/src/xen/xen/.xen-syms.0
> > > ld: error: xen.lds:260: malformed number: |
> > > >>> ASSERT(__image_base__ > (((((((((261 >> 8) * 0xffff000000000000) | 
> > > >>> (261 << 39))) + ((1 << 39) / 2)) + (64 << 30)) + (1 << 30)) + (1 << 
> > > >>> 30))) ||
> > > >>>                                                                       
> > > >>>                                                                       
> > > >>>   ^
> > >
> > > Signed-off-by: Roger Pau Monné <roger.pau@xxxxxxxxxx>
> > > ---
> > > Cc: Jan Beulich <jbeulich@xxxxxxxx>
> > > Cc: Andrew Cooper <andrew.cooper3@xxxxxxxxxx>
> > > Cc: Daniel Kiper <daniel.kiper@xxxxxxxxxx>
> > > ---
> > >  xen/arch/x86/xen.lds.S | 2 +-
> > >  1 file changed, 1 insertion(+), 1 deletion(-)
> > >
> > > diff --git a/xen/arch/x86/xen.lds.S b/xen/arch/x86/xen.lds.S
> > > index 70afedd31d..326e885402 100644
> > > --- a/xen/arch/x86/xen.lds.S
> > > +++ b/xen/arch/x86/xen.lds.S
> > > @@ -331,7 +331,7 @@ SECTIONS
> > >    .comment 0 : { *(.comment) }
> > >  }
> > >
> > > -ASSERT(__image_base__ > XEN_VIRT_START ||
> > > +ASSERT(__image_base__ > XEN_VIRT_START |
> > >         __2M_rwdata_end <= XEN_VIRT_END - NR_CPUS * PAGE_SIZE,
> > >         "Xen image overlaps stubs area")
> >
> > I am not happy with this change. Is the same needed for any "&&"?
>
> I haven't tried, but I assume both '||' and '&&' would be equally
> broken. There's no '&&' ATM anyway.
>
> > Anyway, if maintainers are OK with that I will just ask you to put
> > the comment before the ASSERT() why you use "|" instead of "||".
>
> OK, I can add something like:
>
> "lld (LLVM linker) version 6.0.0 doesn't support '||', so use '|'
> instead."

I am OK with that.

Daniel

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