xen/arm: Enable use of dump_pt_walk() early during boot

At the moment, dump_pt_walk() is using map_domain_page() to map
the page tables.

map_domain_page() is only usuable after init_domheap_mappings() is called
(arm32) or the xenheap has been initialized (arm64).

This means it can be hard to diagnose incorrect page-tables during
early boot. So update dump_pt_walk() to xen_{, un}map_table() instead.

Note that the two helpers are moved earlier to avoid forward declaring
them.

Signed-off-by: Julien Grall <jgrall@amazon.com>
Reviewed-by: Stefano Stabellini <sstabellini@kernel.org>

xen/arch/arm/mm.c

@@ -177,6 +177,30 @@ static void __init __maybe_unused build_assertions(void)
 #undef CHECK_SAME_SLOT
 }
 
+static lpae_t *xen_map_table(mfn_t mfn)
+{
+    /*
+     * During early boot, map_domain_page() may be unusable. Use the
+     * PMAP to map temporarily a page-table.
+     */
+    if ( system_state == SYS_STATE_early_boot )
+        return pmap_map(mfn);
+
+    return map_domain_page(mfn);
+}
+
+static void xen_unmap_table(const lpae_t *table)
+{
+    /*
+     * During early boot, xen_map_table() will not use map_domain_page()
+     * but the PMAP.
+     */
+    if ( system_state == SYS_STATE_early_boot )
+        pmap_unmap(table);
+    else
+        unmap_domain_page(table);
+}
+
 void dump_pt_walk(paddr_t ttbr, paddr_t addr,
                   unsigned int root_level,
                   unsigned int nr_root_tables)
@@ -216,7 +240,7 @@ void dump_pt_walk(paddr_t ttbr, paddr_t addr,
     else
         root_table = 0;
 
-    mapping = map_domain_page(mfn_add(root_mfn, root_table));
+    mapping = xen_map_table(mfn_add(root_mfn, root_table));
 
     for ( level = root_level; ; level++ )
     {
@@ -232,11 +256,11 @@ void dump_pt_walk(paddr_t ttbr, paddr_t addr,
             break;
 
         /* For next iteration */
-        unmap_domain_page(mapping);
-        mapping = map_domain_page(lpae_get_mfn(pte));
+        xen_unmap_table(mapping);
+        mapping = xen_map_table(lpae_get_mfn(pte));
     }
 
-    unmap_domain_page(mapping);
+    xen_unmap_table(mapping);
 }
 
 void dump_hyp_walk(vaddr_t addr)
@@ -699,30 +723,6 @@ void *ioremap(paddr_t pa, size_t len)
     return ioremap_attr(pa, len, PAGE_HYPERVISOR_NOCACHE);
 }
 
-static lpae_t *xen_map_table(mfn_t mfn)
-{
-    /*
-     * During early boot, map_domain_page() may be unusable. Use the
-     * PMAP to map temporarily a page-table.
-     */
-    if ( system_state == SYS_STATE_early_boot )
-        return pmap_map(mfn);
-
-    return map_domain_page(mfn);
-}
-
-static void xen_unmap_table(const lpae_t *table)
-{
-    /*
-     * During early boot, xen_map_table() will not use map_domain_page()
-     * but the PMAP.
-     */
-    if ( system_state == SYS_STATE_early_boot )
-        pmap_unmap(table);
-    else
-        unmap_domain_page(table);
-}
-
 static int create_xen_table(lpae_t *entry)
 {
     mfn_t mfn;