1 files changed, 37 insertions, 0 deletions

diff --git a/arch/x86/xen/mmu.c b/arch/x86/xen/mmu.c
index 5e41f7fc6cf1..d2e8ed1aff3d 100644
--- a/arch/x86/xen/mmu.c
+++ b/arch/x86/xen/mmu.c
@@ -1396,6 +1396,43 @@ static void xen_pgd_free(struct mm_struct *mm, pgd_t *pgd)
 #endif
 }
 
+#ifdef CONFIG_HIGHPTE
+static void *xen_kmap_atomic_pte(struct page *page, enum km_type type)
+{
+        pgprot_t prot = PAGE_KERNEL;
+
+        if (PagePinned(page))
+                prot = PAGE_KERNEL_RO;
+
+        if (0 && PageHighMem(page))
+                printk("mapping highpte %lx type %d prot %s\n",
+                       page_to_pfn(page), type,
+                       (unsigned long)pgprot_val(prot) & _PAGE_RW ? "WRITE" : "READ");
+
+        return kmap_atomic_prot(page, type, prot);
+}
+#endif
+
+#ifdef CONFIG_X86_32
+static __init pte_t mask_rw_pte(pte_t *ptep, pte_t pte)
+{
+        /* If there's an existing pte, then don't allow _PAGE_RW to be set */
+        if (pte_val_ma(*ptep) & _PAGE_PRESENT)
+                pte = __pte_ma(((pte_val_ma(*ptep) & _PAGE_RW) | ~_PAGE_RW) &
+                               pte_val_ma(pte));
+
+        return pte;
+}
+
+/* Init-time set_pte while constructing initial pagetables, which
+   doesn't allow RO pagetable pages to be remapped RW */
+static __init void xen_set_pte_init(pte_t *ptep, pte_t pte)
+{
+        pte = mask_rw_pte(ptep, pte);
+
+        xen_set_pte(ptep, pte);
+}
+#endif
 
 /* Early in boot, while setting up the initial pagetable, assume
    everything is pinned. */