acpi/x86: introduce __apci_map_table, v4

to prevent wrongly overwriting fixmap that still want to use.

ACPI used to rely on low mappings being all linearly mapped and
grew a habit: it never really unmapped certain kinds of tables
after use.

This can cause problems - for example the hypothetical case
when some spurious access still references it.

v2: remove prev_map and prev_size in __apci_map_table
v3: let acpi_os_unmap_memory() call early_iounmap too, so remove extral calling to
early_acpi_os_unmap_memory
v4: fix typo in one acpi_get_table_with_size calling

Signed-off-by: Yinghai Lu <yhlu.kernel@gmail.com>
Acked-by: Len Brown <len.brown@intel.com>
Signed-off-by: Ingo Molnar <mingo@elte.hu>

drivers/acpi/acpica/tbxface.c

@@ -365,7 +365,7 @@ ACPI_EXPORT_SYMBOL(acpi_unload_table_id)
 
 /*******************************************************************************
  *
- * FUNCTION:    acpi_get_table
+ * FUNCTION:    acpi_get_table_with_size
  *
  * PARAMETERS:  Signature           - ACPI signature of needed table
  *              Instance            - Which instance (for SSDTs)
@@ -377,8 +377,9 @@ ACPI_EXPORT_SYMBOL(acpi_unload_table_id)
  *
  *****************************************************************************/
 acpi_status
-acpi_get_table(char *signature,
-	       u32 instance, struct acpi_table_header **out_table)
+acpi_get_table_with_size(char *signature,
+	       u32 instance, struct acpi_table_header **out_table,
+	       acpi_size *tbl_size)
 {
        u32 i;
        u32 j;
@@ -408,6 +409,7 @@ acpi_get_table(char *signature,
 		    acpi_tb_verify_table(&acpi_gbl_root_table_list.tables[i]);
 		if (ACPI_SUCCESS(status)) {
 			*out_table = acpi_gbl_root_table_list.tables[i].pointer;
+			*tbl_size = acpi_gbl_root_table_list.tables[i].length;
 		}
 
 		if (!acpi_gbl_permanent_mmap) {
@@ -420,6 +422,15 @@ acpi_get_table(char *signature,
 	return (AE_NOT_FOUND);
 }
 
+acpi_status
+acpi_get_table(char *signature,
+	       u32 instance, struct acpi_table_header **out_table)
+{
+	acpi_size tbl_size;
+
+	return acpi_get_table_with_size(signature,
+		       instance, out_table, &tbl_size);
+}
 ACPI_EXPORT_SYMBOL(acpi_get_table)
 
 /*******************************************************************************