xen/arm: Restrict zeroeth_table_offset for ARM_64

When 32 bit physical addresses are used (ie PHYS_ADDR_T_32=y),
"va >> ZEROETH_SHIFT" causes an overflow.
Also, there is no zeroeth level page table on Arm32.

Also took the opportunity to clean up dump_pt_walk(). One could use
DECLARE_OFFSETS() macro instead of declaring an array of page table
offsets.

Signed-off-by: Ayan Kumar Halder <ayan.kumar.halder@amd.com>
Reviewed-by: Michal Orzel <michal.orzel@amd.com>
Acked-by: Julien Grall <jgrall@amazon.com>

xen/arch/arm/include/asm/lpae.h

@@ -259,7 +259,11 @@ lpae_t mfn_to_xen_entry(mfn_t mfn, unsigned int attr);
 #define first_table_offset(va)  TABLE_OFFSET(first_linear_offset(va))
 #define second_table_offset(va) TABLE_OFFSET(second_linear_offset(va))
 #define third_table_offset(va)  TABLE_OFFSET(third_linear_offset(va))
+#ifdef CONFIG_PHYS_ADDR_T_32
+#define zeroeth_table_offset(va)  0
+#else
 #define zeroeth_table_offset(va)  TABLE_OFFSET(zeroeth_linear_offset(va))
+#endif
 
 /*
  * Macros to define page-tables:

xen/arch/arm/mm.c

@@ -233,12 +233,7 @@ void dump_pt_walk(paddr_t ttbr, paddr_t addr,
 {
     static const char *level_strs[4] = { "0TH", "1ST", "2ND", "3RD" };
     const mfn_t root_mfn = maddr_to_mfn(ttbr);
-    const unsigned int offsets[4] = {
-        zeroeth_table_offset(addr),
-        first_table_offset(addr),
-        second_table_offset(addr),
-        third_table_offset(addr)
-    };
+    DECLARE_OFFSETS(offsets, addr);
     lpae_t pte, *mapping;
     unsigned int level, root_table;