Implement multi-level page tables.

Define L1_MAP_ADDR_SPACE_BITS to be either the virtual address size
(in user mode) or physical address size (in system mode), and use
that to size l1_map.  This rewrites page_find_alloc, page_flush_tb,
and walk_memory_regions.

Use TARGET_PHYS_ADDR_SPACE_BITS for the physical memory map based
off of l1_phys_map.  This rewrites page_phys_find_alloc and
phys_page_for_each.

Signed-off-by: Richard Henderson <rth@twiddle.net>

cpu-all.h

@@ -745,8 +745,11 @@ extern unsigned long qemu_host_page_mask;
 #define PAGE_RESERVED  0x0020
 
 void page_dump(FILE *f);
-int walk_memory_regions(void *,
-    int (*fn)(void *, unsigned long, unsigned long, unsigned long));
+
+typedef int (*walk_memory_regions_fn)(void *, unsigned long,
+                                      unsigned long, unsigned long);
+int walk_memory_regions(void *, walk_memory_regions_fn);
+
 int page_get_flags(target_ulong address);
 void page_set_flags(target_ulong start, target_ulong end, int flags);
 int page_check_range(target_ulong start, target_ulong len, int flags);