ARM: pgtable: collect up identity mapping functions

We have two places where we create identity mappings - one when we bring
secondary CPUs online, and one where we setup some mappings for soft-
reboot.  Combine these two into a single implementation.  Also collect
the identity mapping deletion function.

Signed-off-by: Russell King <rmk+kernel@arm.linux.org.uk>

1 files changed, 51 insertions, 0 deletions

diff --git a/arch/arm/mm/idmap.c b/arch/arm/mm/idmap.c
new file mode 100644
index 000000000000..034124d1272d
--- /dev/null
+++ b/arch/arm/mm/idmap.c
@@ -0,0 +1,51 @@
+#include <linux/kernel.h>
+
+#include <asm/cputype.h>
+#include <asm/pgalloc.h>
+#include <asm/pgtable.h>
+
+void identity_mapping_add(pgd_t *pgd, unsigned long addr, unsigned long end)
+{
+        unsigned long prot;
+
+        prot = PMD_TYPE_SECT | PMD_SECT_AP_WRITE;
+        if (cpu_architecture() <= CPU_ARCH_ARMv5TEJ && !cpu_is_xscale())
+                prot |= PMD_BIT4;
+
+        for (addr &= PGDIR_MASK; addr < end;) {
+                pmd_t *pmd = pmd_offset(pgd + pgd_index(addr), addr);
+                pmd[0] = __pmd(addr | prot);
+                addr += SECTION_SIZE;
+                pmd[1] = __pmd(addr | prot);
+                addr += SECTION_SIZE;
+                flush_pmd_entry(pmd);
+        }
+}
+
+#ifdef CONFIG_SMP
+void identity_mapping_del(pgd_t *pgd, unsigned long addr, unsigned long end)
+{
+        for (addr &= PGDIR_MASK; addr < end; addr += PGDIR_SIZE) {
+                pmd_t *pmd = pmd_offset(pgd + pgd_index(addr), addr);
+                pmd[0] = __pmd(0);
+                pmd[1] = __pmd(0);
+                clean_pmd_entry(pmd);
+        }
+}
+#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();
+}