xen/arm64: head: only use the macro load_paddr() in the MMU code

The macro load_paddr() requires to know the offset between the
physical location of Xen and the virtual location.

When using the MPU, x20 will always be 0. Rather than wasting
a register for a compile-time constant value, it would be best if
we can avoid using load_paddr() altogether in the common head.S code.

The current use of load_paddr() are equivalent to adr_l() because
the MMU is off.

All the use of load_paddr() in arm64/head.S are now replaced with
adr_l(). With that, load_paddr() can now be moved in arm64/mmu/head.S.

For now, x20 is still unconditionally set. But this could change
in the future if needed.

Signed-off-by: Julien Grall <julien@xen.org>
Reviewed-by: Michal Orzel <michal.orzel@amd.com>

xen/arch/arm/arm64/head.S

@@ -259,7 +259,7 @@ real_start_efi:
 
         /* Using the DTB in the .dtb section? */
 .ifnes CONFIG_DTB_FILE,""
-        load_paddr x21, _sdtb
+        adr_l x21, _sdtb
 .endif
 
         /* Initialize the UART if earlyprintk has been enabled. */
@@ -301,7 +301,7 @@ GLOBAL(init_secondary)
         bic   x24, x0, x13           /* Mask out flags to get CPU ID */
 
         /* Wait here until __cpu_up is ready to handle the CPU */
-        load_paddr x0, smp_up_cpu
+        adr_l x0, smp_up_cpu
         dsb   sy
 2:      ldr   x1, [x0]
         cmp   x1, x24

xen/arch/arm/arm64/mmu/head.S

@@ -19,6 +19,12 @@
 #define XEN_FIRST_SLOT      first_table_offset(XEN_VIRT_START)
 #define XEN_SECOND_SLOT     second_table_offset(XEN_VIRT_START)
 
+/* Load the physical address of a symbol into xb */
+.macro load_paddr xb, sym
+        ldr \xb, =\sym
+        add \xb, \xb, x20
+.endm
+
 /*
  * Flush local TLBs
  *

xen/arch/arm/include/asm/arm64/macros.h

@@ -62,12 +62,6 @@
         add  \dst, \dst, :lo12:\sym
 .endm
 
-/* Load the physical address of a symbol into xb */
-.macro load_paddr xb, sym
-        ldr \xb, =\sym
-        add \xb, \xb, x20
-.endm
-
 /*
  * Register aliases.
  */