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

[Jason Andryuk <jason.andryuk@amd.com>]

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