1 files changed, 79 insertions, 0 deletions

diff --git a/arch/x86/mm/ident_map.c b/arch/x86/mm/ident_map.c
new file mode 100644
index 000000000000..ec21796ac5fd
--- /dev/null
+++ b/arch/x86/mm/ident_map.c
@@ -0,0 +1,79 @@
+/*
+ * Helper routines for building identity mapping page tables. This is
+ * included by both the compressed kernel and the regular kernel.
+ */
+
+static void ident_pmd_init(unsigned long pmd_flag, pmd_t *pmd_page,
+                           unsigned long addr, unsigned long end)
+{
+        addr &= PMD_MASK;
+        for (; addr < end; addr += PMD_SIZE) {
+                pmd_t *pmd = pmd_page + pmd_index(addr);
+
+                if (!pmd_present(*pmd))
+                        set_pmd(pmd, __pmd(addr | pmd_flag));
+        }
+}
+
+static int ident_pud_init(struct x86_mapping_info *info, pud_t *pud_page,
+                          unsigned long addr, unsigned long end)
+{
+        unsigned long next;
+
+        for (; addr < end; addr = next) {
+                pud_t *pud = pud_page + pud_index(addr);
+                pmd_t *pmd;
+
+                next = (addr & PUD_MASK) + PUD_SIZE;
+                if (next > end)
+                        next = end;
+
+                if (pud_present(*pud)) {
+                        pmd = pmd_offset(pud, 0);
+                        ident_pmd_init(info->pmd_flag, pmd, addr, next);
+                        continue;
+                }
+                pmd = (pmd_t *)info->alloc_pgt_page(info->context);
+                if (!pmd)
+                        return -ENOMEM;
+                ident_pmd_init(info->pmd_flag, pmd, addr, next);
+                set_pud(pud, __pud(__pa(pmd) | _KERNPG_TABLE));
+        }
+
+        return 0;
+}
+
+int kernel_ident_mapping_init(struct x86_mapping_info *info, pgd_t *pgd_page,
+                              unsigned long addr, unsigned long end)
+{
+        unsigned long next;
+        int result;
+        int off = info->kernel_mapping ? pgd_index(__PAGE_OFFSET) : 0;
+
+        for (; addr < end; addr = next) {
+                pgd_t *pgd = pgd_page + pgd_index(addr) + off;
+                pud_t *pud;
+
+                next = (addr & PGDIR_MASK) + PGDIR_SIZE;
+                if (next > end)
+                        next = end;
+
+                if (pgd_present(*pgd)) {
+                        pud = pud_offset(pgd, 0);
+                        result = ident_pud_init(info, pud, addr, next);
+                        if (result)
+                                return result;
+                        continue;
+                }
+
+                pud = (pud_t *)info->alloc_pgt_page(info->context);
+                if (!pud)
+                        return -ENOMEM;
+                result = ident_pud_init(info, pud, addr, next);
+                if (result)
+                        return result;
+                set_pgd(pgd, __pgd(__pa(pud) | _KERNPG_TABLE));
+        }
+
+        return 0;
+}