1 files changed, 57 insertions, 10 deletions

diff --git a/drivers/acpi/tables.c b/drivers/acpi/tables.c
index 8fccbe49612a..7553774a22b7 100644
--- a/drivers/acpi/tables.c
+++ b/drivers/acpi/tables.c
@@ -49,6 +49,15 @@ static struct acpi_table_desc initial_tables[ACPI_MAX_TABLES] __initdata;
 
 static int acpi_apic_instance __initdata;
 
+enum acpi_subtable_type {
+        ACPI_SUBTABLE_COMMON,
+};
+
+struct acpi_subtable_entry {
+        union acpi_subtable_headers *hdr;
+        enum acpi_subtable_type type;
+};
+
 /*
  * Disable table checksum verification for the early stage due to the size
  * limitation of the current x86 early mapping implementation.
@@ -217,6 +226,42 @@ void acpi_table_print_madt_entry(struct acpi_subtable_header *header)
         }
 }
 
+static unsigned long __init
+acpi_get_entry_type(struct acpi_subtable_entry *entry)
+{
+        switch (entry->type) {
+        case ACPI_SUBTABLE_COMMON:
+                return entry->hdr->common.type;
+        }
+        return 0;
+}
+
+static unsigned long __init
+acpi_get_entry_length(struct acpi_subtable_entry *entry)
+{
+        switch (entry->type) {
+        case ACPI_SUBTABLE_COMMON:
+                return entry->hdr->common.length;
+        }
+        return 0;
+}
+
+static unsigned long __init
+acpi_get_subtable_header_length(struct acpi_subtable_entry *entry)
+{
+        switch (entry->type) {
+        case ACPI_SUBTABLE_COMMON:
+                return sizeof(entry->hdr->common);
+        }
+        return 0;
+}
+
+static enum acpi_subtable_type __init
+acpi_get_subtable_type(char *id)
+{
+        return ACPI_SUBTABLE_COMMON;
+}
+
 /**
  * acpi_parse_entries_array - for each proc_num find a suitable subtable
  *
@@ -246,8 +291,8 @@ acpi_parse_entries_array(char *id, unsigned long table_size,
                 struct acpi_subtable_proc *proc, int proc_num,
                 unsigned int max_entries)
 {
-        struct acpi_subtable_header *entry;
-        unsigned long table_end;
+        struct acpi_subtable_entry entry;
+        unsigned long table_end, subtable_len, entry_len;
         int count = 0;
         int errs = 0;
         int i;
@@ -270,19 +315,20 @@ acpi_parse_entries_array(char *id, unsigned long table_size,
 
         /* Parse all entries looking for a match. */
 
-        entry = (struct acpi_subtable_header *)
+        entry.type = acpi_get_subtable_type(id);
+        entry.hdr = (union acpi_subtable_headers *)
             ((unsigned long)table_header + table_size);
+        subtable_len = acpi_get_subtable_header_length(&entry);
 
-        while (((unsigned long)entry) + sizeof(struct acpi_subtable_header) <
-               table_end) {
+        while (((unsigned long)entry.hdr) + subtable_len  < table_end) {
                 if (max_entries && count >= max_entries)
                         break;
 
                 for (i = 0; i < proc_num; i++) {
-                        if (entry->type != proc[i].id)
+                        if (acpi_get_entry_type(&entry) != proc[i].id)
                                 continue;
                         if (!proc[i].handler ||
-                             (!errs && proc[i].handler(entry, table_end))) {
+                             (!errs && proc[i].handler(entry.hdr, table_end))) {
                                 errs++;
                                 continue;
                         }
@@ -297,13 +343,14 @@ acpi_parse_entries_array(char *id, unsigned long table_size,
                  * If entry->length is 0, break from this loop to avoid
                  * infinite loop.
                  */
-                if (entry->length == 0) {
+                entry_len = acpi_get_entry_length(&entry);
+                if (entry_len == 0) {
                         pr_err("[%4.4s:0x%02x] Invalid zero length\n", id, proc->id);
                         return -EINVAL;
                 }
 
-                entry = (struct acpi_subtable_header *)
-                    ((unsigned long)entry + entry->length);
+                entry.hdr = (union acpi_subtable_headers *)
+                    ((unsigned long)entry.hdr + entry_len);
         }
 
         if (max_entries && count > max_entries) {