x86/boot: Rename l?_identmap to l?_directmap

Since c/s faa85d4fb3 "x86/boot: Don't map 0 during boot", l1_identmap no
longer has an alias mapped at 0, meaning that none of the l?_identmap[]
pagetables are actually an identity map.

Rename them to l?_directmap, which avoids any kind of implication that they
might be mapped at 0.

Signed-off-by: Andrew Cooper <andrew.cooper3@citrix.com>
Acked-by: Jan Beulich <jbeulich@suse.com>

xen/arch/x86/boot/head.S

@@ -678,7 +678,7 @@ trampoline_setup:
         shr     $(L2_PAGETABLE_SHIFT-3),%ebx
         mov     $8,%ecx
 1:      mov     %eax,sym_fs(l2_bootmap)-8(%ebx,%ecx,8)
-        mov     %eax,sym_fs(l2_identmap)-8(%ebx,%ecx,8)
+        mov     %eax,sym_fs(l2_directmap)-8(%ebx,%ecx,8)
         sub     $(1<<L2_PAGETABLE_SHIFT),%eax
         loop    1b
 

xen/arch/x86/boot/x86_64.S

@@ -51,7 +51,7 @@ GLOBAL(stack_start)
  * of physical memory. In any case the VGA hole should be mapped with type UC.
  * Uses 1x 4k page.
  */
-l1_identmap:
+l1_directmap:
         pfn = 0
         .rept L1_PAGETABLE_ENTRIES
         /* VGA hole (0xa0000-0xc0000) should be mapped UC-. */
@@ -62,7 +62,7 @@ l1_identmap:
         .endif
         pfn = pfn + 1
         .endr
-        .size l1_identmap, . - l1_identmap
+        .size l1_directmap, . - l1_directmap
 
 /*
  * __page_tables_{start,end} cover the range of pagetables which need
@@ -73,12 +73,12 @@ GLOBAL(__page_tables_start)
 
 /*
  * Space for 4G worth of 2M mappings, first 2M actually mapped via
- * l1_identmap[].  Uses 4x 4k pages.
+ * l1_directmap[].  Uses 4x 4k pages.
  */
-GLOBAL(l2_identmap)
-        .quad sym_offs(l1_identmap) + __PAGE_HYPERVISOR
+GLOBAL(l2_directmap)
+        .quad sym_offs(l1_directmap) + __PAGE_HYPERVISOR
         .fill 4 * L2_PAGETABLE_ENTRIES - 1, 8, 0
-        .size l2_identmap, . - l2_identmap
+        .size l2_directmap, . - l2_directmap
 
 /*
  * L2 mapping the 1GB Xen text/data/bss region.  At boot it maps 16MB from
@@ -108,15 +108,15 @@ l2_fixmap:
         .endr
         .size l2_fixmap, . - l2_fixmap
 
-/* Identity map, covering the 4 l2_identmap tables.  Uses 1x 4k page. */
-l3_identmap:
+/* Direct map, initially covering the 4 l2_directmap tables.  Uses 1x 4k page. */
+l3_directmap:
         idx = 0
         .rept 4
-        .quad sym_offs(l2_identmap) + (idx << PAGE_SHIFT) + __PAGE_HYPERVISOR
+        .quad sym_offs(l2_directmap) + (idx << PAGE_SHIFT) + __PAGE_HYPERVISOR
         idx = idx + 1
         .endr
         .fill L3_PAGETABLE_ENTRIES - 4, 8, 0
-        .size l3_identmap, . - l3_identmap
+        .size l3_directmap, . - l3_directmap
 
 /* L3 mapping the fixmap.  Uses 1x 4k page. */
 l3_xenmap:
@@ -139,7 +139,7 @@ GLOBAL(idle_pg_table)
         idx = 1
         .rept L4_PAGETABLE_ENTRIES - 1
         .if idx == l4_table_offset(DIRECTMAP_VIRT_START)
-        .quad sym_offs(l3_identmap) + __PAGE_HYPERVISOR
+        .quad sym_offs(l3_directmap) + __PAGE_HYPERVISOR
         .elseif idx == l4_table_offset(XEN_VIRT_START)
         .quad sym_offs(l3_xenmap) + __PAGE_HYPERVISOR
         .else

xen/arch/x86/efi/efi-boot.h

@@ -59,7 +59,7 @@ static void __init efi_arch_relocate_image(unsigned long delta)
         /*
          * Relevant l{2,3}_bootmap entries get initialized explicitly in
          * efi_arch_memory_setup(), so we must not apply relocations there.
-         * l2_identmap's first slot, otoh, should be handled normally, as
+         * l2_directmap's first slot, otoh, should be handled normally, as
          * efi_arch_memory_setup() won't touch it (xen_phys_start should
          * never be zero).
          */
@@ -586,8 +586,8 @@ static void __init efi_arch_memory_setup(void)
         return;
 
     /* Check that there is at least 4G of mapping space in l2_*map[] */
-    BUILD_BUG_ON((sizeof(l2_bootmap)  / L2_PAGETABLE_ENTRIES) < 4);
-    BUILD_BUG_ON((sizeof(l2_identmap) / L2_PAGETABLE_ENTRIES) < 4);
+    BUILD_BUG_ON((sizeof(l2_bootmap)   / L2_PAGETABLE_ENTRIES) < 4);
+    BUILD_BUG_ON((sizeof(l2_directmap) / L2_PAGETABLE_ENTRIES) < 4);
 
     /* Initialize L3 boot-map page directory entries. */
     for ( i = 0; i < 4; ++i )
@@ -603,7 +603,7 @@ static void __init efi_arch_memory_setup(void)
         unsigned int slot = (xen_phys_start >> L2_PAGETABLE_SHIFT) + i;
         paddr_t addr = slot << L2_PAGETABLE_SHIFT;
 
-        l2_identmap[slot] = l2e_from_paddr(addr, PAGE_HYPERVISOR|_PAGE_PSE);
+        l2_directmap[slot] = l2e_from_paddr(addr, PAGE_HYPERVISOR|_PAGE_PSE);
         l2_bootmap[slot] = l2e_from_paddr(addr, __PAGE_HYPERVISOR|_PAGE_PSE);
     }
 }

xen/arch/x86/setup.c

@@ -1031,7 +1031,7 @@ void __init noreturn __start_xen(unsigned long mbi_p)
     for ( i = boot_e820.nr_map-1; i >= 0; i-- )
     {
         uint64_t s, e, mask = (1UL << L2_PAGETABLE_SHIFT) - 1;
-        uint64_t end, limit = ARRAY_SIZE(l2_identmap) << L2_PAGETABLE_SHIFT;
+        uint64_t end, limit = ARRAY_SIZE(l2_directmap) << L2_PAGETABLE_SHIFT;
 
         if ( boot_e820.map[i].type != E820_RAM )
             continue;
@@ -1136,7 +1136,7 @@ void __init noreturn __start_xen(unsigned long mbi_p)
             /* The only data mappings to be relocated are in the Xen area. */
             pl2e = __va(__pa(l2_xenmap));
             /*
-             * Undo the temporary-hooking of the l1_identmap.  __2M_text_start
+             * Undo the temporary-hooking of the l1_directmap.  __2M_text_start
              * is contained in this PTE.
              */
             BUG_ON(using_2M_mapping() &&
@@ -1349,7 +1349,7 @@ void __init noreturn __start_xen(unsigned long mbi_p)
         /* Need to create mappings above PREBUILT_MAP_LIMIT. */
         map_s = max_t(uint64_t, s, PREBUILT_MAP_LIMIT);
         map_e = min_t(uint64_t, e,
-                      ARRAY_SIZE(l2_identmap) << L2_PAGETABLE_SHIFT);
+                      ARRAY_SIZE(l2_directmap) << L2_PAGETABLE_SHIFT);
 
         /* Pass mapped memory to allocator /before/ creating new mappings. */
         init_boot_pages(s, min(map_s, e));

xen/include/asm-x86/page.h

@@ -293,7 +293,7 @@ extern unsigned int   m2p_compat_vstart;
 extern l2_pgentry_t l2_xenmap[L2_PAGETABLE_ENTRIES],
     l2_bootmap[4*L2_PAGETABLE_ENTRIES];
 extern l3_pgentry_t l3_bootmap[L3_PAGETABLE_ENTRIES];
-extern l2_pgentry_t l2_identmap[4*L2_PAGETABLE_ENTRIES];
+extern l2_pgentry_t l2_directmap[4*L2_PAGETABLE_ENTRIES];
 extern l1_pgentry_t l1_fixmap[L1_PAGETABLE_ENTRIES];
 void paging_init(void);
 void efi_update_l4_pgtable(unsigned int l4idx, l4_pgentry_t);