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.andr...@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