1 files changed, 67 insertions, 0 deletions

diff --git a/arch/arm/mm/idmap.c b/arch/arm/mm/idmap.c
new file mode 100644
index 000000000000..57299446f787
--- /dev/null
+++ b/arch/arm/mm/idmap.c
@@ -0,0 +1,67 @@
+#include <linux/kernel.h>
+
+#include <asm/cputype.h>
+#include <asm/pgalloc.h>
+#include <asm/pgtable.h>
+
+static void idmap_add_pmd(pgd_t *pgd, unsigned long addr, unsigned long end,
+        unsigned long prot)
+{
+        pmd_t *pmd = pmd_offset(pgd, addr);
+
+        addr = (addr & PMD_MASK) | prot;
+        pmd[0] = __pmd(addr);
+        addr += SECTION_SIZE;
+        pmd[1] = __pmd(addr);
+        flush_pmd_entry(pmd);
+}
+
+void identity_mapping_add(pgd_t *pgd, unsigned long addr, unsigned long end)
+{
+        unsigned long prot, next;
+
+        prot = PMD_TYPE_SECT | PMD_SECT_AP_WRITE;
+        if (cpu_architecture() <= CPU_ARCH_ARMv5TEJ && !cpu_is_xscale())
+                prot |= PMD_BIT4;
+
+        pgd += pgd_index(addr);
+        do {
+                next = pgd_addr_end(addr, end);
+                idmap_add_pmd(pgd, addr, next, prot);
+        } while (pgd++, addr = next, addr != end);
+}
+
+#ifdef CONFIG_SMP
+static void idmap_del_pmd(pgd_t *pgd, unsigned long addr, unsigned long end)
+{
+        pmd_t *pmd = pmd_offset(pgd, addr);
+        pmd_clear(pmd);
+}
+
+void identity_mapping_del(pgd_t *pgd, unsigned long addr, unsigned long end)
+{
+        unsigned long next;
+
+        pgd += pgd_index(addr);
+        do {
+                next = pgd_addr_end(addr, end);
+                idmap_del_pmd(pgd, addr, next);
+        } while (pgd++, addr = next, addr != end);
+}
+#endif
+
+/*
+ * In order to soft-boot, we need to insert a 1:1 mapping in place of
+ * the user-mode pages.  This will then ensure that we have predictable
+ * results when turning the mmu off
+ */
+void setup_mm_for_reboot(char mode)
+{
+        /*
+         * We need to access to user-mode page tables here. For kernel threads
+         * we don't have any user-mode mappings so we use the context that we
+         * "borrowed".
+         */
+        identity_mapping_add(current->active_mm->pgd, 0, TASK_SIZE);
+        local_flush_tlb_all();
+}