sh: Fix up PUD trampling in ranged page table init for X2TLB.

page_table_range_init() presently allocates a PUD page for the 3-level
page table case on X2 TLB configurations on each successive call. This
results in the previous PUD page being trampled when PMDs with an
overlapping PUD are initialized. This case was triggered by putting
persistent kmaps immediately below the fixmap range for highmem.

Signed-off-by: Paul Mundt <lethal@linux-sh.org>

arch/sh/mm/init.c

@@ -47,7 +47,6 @@ static pte_t *__get_pte_phys(unsigned long addr)
 	pgd_t *pgd;
 	pud_t *pud;
 	pmd_t *pmd;
-	pte_t *pte;
 
 	pgd = pgd_offset_k(addr);
 	if (pgd_none(*pgd)) {
@@ -67,8 +66,7 @@ static pte_t *__get_pte_phys(unsigned long addr)
 		return NULL;
 	}
 
-	pte = pte_offset_kernel(pmd, addr);
-	return pte;
+	return pte_offset_kernel(pmd, addr);
 }
 
 static void set_pte_phys(unsigned long addr, unsigned long phys, pgprot_t prot)
@@ -125,13 +123,45 @@ void __clear_fixmap(enum fixed_addresses idx, pgprot_t prot)
 	clear_pte_phys(address, prot);
 }
 
+static pmd_t * __init one_md_table_init(pud_t *pud)
+{
+	if (pud_none(*pud)) {
+		pmd_t *pmd;
+
+		pmd = alloc_bootmem_pages(PAGE_SIZE);
+		pud_populate(&init_mm, pud, pmd);
+		BUG_ON(pmd != pmd_offset(pud, 0));
+	}
+
+	return pmd_offset(pud, 0);
+}
+
+static pte_t * __init one_page_table_init(pmd_t *pmd)
+{
+	if (pmd_none(*pmd)) {
+		pte_t *pte;
+
+		pte = alloc_bootmem_pages(PAGE_SIZE);
+		pmd_populate_kernel(&init_mm, pmd, pte);
+		BUG_ON(pte != pte_offset_kernel(pmd, 0));
+	}
+
+	return pte_offset_kernel(pmd, 0);
+}
+
+static pte_t * __init page_table_kmap_check(pte_t *pte, pmd_t *pmd,
+					    unsigned long vaddr, pte_t *lastpte)
+{
+	return pte;
+}
+
 void __init page_table_range_init(unsigned long start, unsigned long end,
 					 pgd_t *pgd_base)
 {
 	pgd_t *pgd;
 	pud_t *pud;
 	pmd_t *pmd;
-	pte_t *pte;
+	pte_t *pte = NULL;
 	int i, j, k;
 	unsigned long vaddr;
 
@@ -144,19 +174,13 @@ void __init page_table_range_init(unsigned long start, unsigned long end,
 	for ( ; (i < PTRS_PER_PGD) && (vaddr != end); pgd++, i++) {
 		pud = (pud_t *)pgd;
 		for ( ; (j < PTRS_PER_PUD) && (vaddr != end); pud++, j++) {
-#ifdef __PAGETABLE_PMD_FOLDED
-			pmd = (pmd_t *)pud;
-#else
-			pmd = (pmd_t *)alloc_bootmem_low_pages(PAGE_SIZE);
-			pud_populate(&init_mm, pud, pmd);
+			pmd = one_md_table_init(pud);
+#ifndef __PAGETABLE_PMD_FOLDED
 			pmd += k;
 #endif
 			for (; (k < PTRS_PER_PMD) && (vaddr != end); pmd++, k++) {
-				if (pmd_none(*pmd)) {
-					pte = (pte_t *) alloc_bootmem_low_pages(PAGE_SIZE);
-					pmd_populate_kernel(&init_mm, pmd, pte);
-					BUG_ON(pte != pte_offset_kernel(pmd, 0));
-				}
+				pte = page_table_kmap_check(one_page_table_init(pmd),
+							    pmd, vaddr, pte);
 				vaddr += PMD_SIZE;
 			}
 			k = 0;