Re: [PATCH 2/5] x86/pvh: Make PVH entrypoint PIC for x86-64

[Jason Andryuk]

On 2024-04-10 17:00, Brian Gerst wrote:
> On Wed, Apr 10, 2024 at 3:50 PM Jason Andryuk <jason.andryuk@xxxxxxx> wrote:

> >          /* 64-bit entry point. */
> >          .code64
> >   1:
> > +       UNWIND_HINT_END_OF_STACK
> > +
> >          /* Set base address in stack canary descriptor. */
> >          mov $MSR_GS_BASE,%ecx
> > -       mov $_pa(canary), %eax
> > +       leal rva(canary)(%ebp), %eax
>
> Since this is in 64-bit mode, RIP-relative addressing can be used.
>
> >          xor %edx, %edx
> >          wrmsr
> >
> >          call xen_prepare_pvh
> >
> >          /* startup_64 expects boot_params in %rsi. */
> > -       mov $_pa(pvh_bootparams), %rsi
> > -       mov $_pa(startup_64), %rax
> > +       lea rva(pvh_bootparams)(%ebp), %rsi
> > +       lea rva(startup_64)(%ebp), %rax
>
> RIP-relative here too.

Yes, thanks for catching that.  With the RIP-relative conversion, there 
is now:
vmlinux.o: warning: objtool: pvh_start_xen+0x10d: relocation to !ENDBR: 
startup_64+0x0

I guess RIP-relative made it visible.  That can be quieted by adding 
ANNOTATE_NOENDBR to startup_64.

Thanks,
Jason