[PATCH] uml: fixrange_init 3-level page table support

From: Al Viro - add three-level page table support to fixrange_init.

Signed-off-by: Jeff Dike <jdike@addtoit.com>
Cc: <viro@parcelfarce.linux.theplanet.co.uk>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>

1 files changed, 31 insertions, 9 deletions

diff --git a/arch/um/kernel/mem.c b/arch/um/kernel/mem.c
index f156661781c..c22825f13e4 100644
--- a/arch/um/kernel/mem.c
+++ b/arch/um/kernel/mem.c
@@ -100,12 +100,37 @@ void mem_init(void)
 #endif
 }
 
+/*
+ * Create a page table and place a pointer to it in a middle page
+ * directory entry.
+ */
+static void __init one_page_table_init(pmd_t *pmd)
+{
+        if (pmd_none(*pmd)) {
+                pte_t *pte = (pte_t *) alloc_bootmem_low_pages(PAGE_SIZE);
+                set_pmd(pmd, __pmd(_KERNPG_TABLE +
+                                           (unsigned long) __pa(pte)));
+                if (pte != pte_offset_kernel(pmd, 0))
+                        BUG();
+        }
+}
+
+static void __init one_md_table_init(pud_t *pud)
+{
+#ifdef CONFIG_3_LEVEL_PGTABLES
+        pmd_t *pmd_table = (pmd_t *) alloc_bootmem_low_pages(PAGE_SIZE);
+        set_pud(pud, __pud(_KERNPG_TABLE + (unsigned long) __pa(pmd_table)));
+        if (pmd_table != pmd_offset(pud, 0))
+                BUG();
+#endif
+}
+
 static void __init fixrange_init(unsigned long start, unsigned long end, 
                                  pgd_t *pgd_base)
 {
         pgd_t *pgd;
+        pud_t *pud;
         pmd_t *pmd;
-        pte_t *pte;
         int i, j;
         unsigned long vaddr;
 
@@ -115,15 +140,12 @@ static void __init fixrange_init(unsigned long start, unsigned long end,
         pgd = pgd_base + i;
 
         for ( ; (i < PTRS_PER_PGD) && (vaddr < end); pgd++, i++) {
-                pmd = (pmd_t *)pgd;
+                pud = pud_offset(pgd, vaddr);
+                if (pud_none(*pud))
+                        one_md_table_init(pud);
+                pmd = pmd_offset(pud, vaddr);
                 for (; (j < PTRS_PER_PMD) && (vaddr != end); pmd++, j++) {
-                        if (pmd_none(*pmd)) {
-                                pte = (pte_t *) alloc_bootmem_low_pages(PAGE_SIZE);
-                                set_pmd(pmd, __pmd(_KERNPG_TABLE + 
-                                                   (unsigned long) __pa(pte)));
-                                if (pte != pte_offset_kernel(pmd, 0))
-                                        BUG();
-                        }
+                        one_page_table_init(pmd);
                         vaddr += PMD_SIZE;
                 }
                 j = 0;