acpi: Create subtable parsing infrastructure

Parsing entries in an ACPI table had assumed a generic header
structure. There is no standard ACPI header, though, so less common
layouts with different field sizes required custom parsers to go through
their subtable entry list.

Create the infrastructure for adding different table types so parsing
the entries array may be more reused for all ACPI system tables and
the common code doesn't need to be duplicated.

Reviewed-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
Acked-by: Jonathan Cameron <Jonathan.Cameron@huawei.com>
Tested-by: Jonathan Cameron <Jonathan.Cameron@huawei.com>
Signed-off-by: Keith Busch <keith.busch@intel.com>
Tested-by: Brice Goglin <Brice.Goglin@inria.fr>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
diff --git a/arch/arm64/kernel/acpi_numa.c b/arch/arm64/kernel/acpi_numa.c
index eac1d0c..7ff8000 100644
--- a/arch/arm64/kernel/acpi_numa.c
+++ b/arch/arm64/kernel/acpi_numa.c
@@ -45,7 +45,7 @@
 	return -EINVAL;
 }
 
-static int __init acpi_parse_gicc_pxm(struct acpi_subtable_header *header,
+static int __init acpi_parse_gicc_pxm(union acpi_subtable_headers *header,
 				      const unsigned long end)
 {
 	struct acpi_srat_gicc_affinity *pa;
diff --git a/arch/arm64/kernel/smp.c b/arch/arm64/kernel/smp.c
index 824de70..bb4b3f0 100644
--- a/arch/arm64/kernel/smp.c
+++ b/arch/arm64/kernel/smp.c
@@ -586,7 +586,7 @@
 }
 
 static int __init
-acpi_parse_gic_cpu_interface(struct acpi_subtable_header *header,
+acpi_parse_gic_cpu_interface(union acpi_subtable_headers *header,
 			     const unsigned long end)
 {
 	struct acpi_madt_generic_interrupt *processor;
@@ -595,7 +595,7 @@
 	if (BAD_MADT_GICC_ENTRY(processor, end))
 		return -EINVAL;
 
-	acpi_table_print_madt_entry(header);
+	acpi_table_print_madt_entry(&header->common);
 
 	acpi_map_gic_cpu_interface(processor);
 
diff --git a/arch/ia64/kernel/acpi.c b/arch/ia64/kernel/acpi.c
index 41eb281..1435e7a 100644
--- a/arch/ia64/kernel/acpi.c
+++ b/arch/ia64/kernel/acpi.c
@@ -177,7 +177,7 @@
 static u8 has_8259;
 
 static int __init
-acpi_parse_lapic_addr_ovr(struct acpi_subtable_header * header,
+acpi_parse_lapic_addr_ovr(union acpi_subtable_headers * header,
 			  const unsigned long end)
 {
 	struct acpi_madt_local_apic_override *lapic;
@@ -195,7 +195,7 @@
 }
 
 static int __init
-acpi_parse_lsapic(struct acpi_subtable_header * header, const unsigned long end)
+acpi_parse_lsapic(union acpi_subtable_headers *header, const unsigned long end)
 {
 	struct acpi_madt_local_sapic *lsapic;
 
@@ -216,7 +216,7 @@
 }
 
 static int __init
-acpi_parse_lapic_nmi(struct acpi_subtable_header * header, const unsigned long end)
+acpi_parse_lapic_nmi(union acpi_subtable_headers * header, const unsigned long end)
 {
 	struct acpi_madt_local_apic_nmi *lacpi_nmi;
 
@@ -230,7 +230,7 @@
 }
 
 static int __init
-acpi_parse_iosapic(struct acpi_subtable_header * header, const unsigned long end)
+acpi_parse_iosapic(union acpi_subtable_headers * header, const unsigned long end)
 {
 	struct acpi_madt_io_sapic *iosapic;
 
@@ -245,7 +245,7 @@
 static unsigned int __initdata acpi_madt_rev;
 
 static int __init
-acpi_parse_plat_int_src(struct acpi_subtable_header * header,
+acpi_parse_plat_int_src(union acpi_subtable_headers * header,
 			const unsigned long end)
 {
 	struct acpi_madt_interrupt_source *plintsrc;
@@ -329,7 +329,7 @@
 }
 
 static int __init
-acpi_parse_int_src_ovr(struct acpi_subtable_header * header,
+acpi_parse_int_src_ovr(union acpi_subtable_headers * header,
 		       const unsigned long end)
 {
 	struct acpi_madt_interrupt_override *p;
@@ -350,7 +350,7 @@
 }
 
 static int __init
-acpi_parse_nmi_src(struct acpi_subtable_header * header, const unsigned long end)
+acpi_parse_nmi_src(union acpi_subtable_headers * header, const unsigned long end)
 {
 	struct acpi_madt_nmi_source *nmi_src;
 
diff --git a/arch/x86/kernel/acpi/boot.c b/arch/x86/kernel/acpi/boot.c
index 8dcbf68..9fc92e4 100644
--- a/arch/x86/kernel/acpi/boot.c
+++ b/arch/x86/kernel/acpi/boot.c
@@ -197,7 +197,7 @@
 }
 
 static int __init
-acpi_parse_x2apic(struct acpi_subtable_header *header, const unsigned long end)
+acpi_parse_x2apic(union acpi_subtable_headers *header, const unsigned long end)
 {
 	struct acpi_madt_local_x2apic *processor = NULL;
 #ifdef CONFIG_X86_X2APIC
@@ -210,7 +210,7 @@
 	if (BAD_MADT_ENTRY(processor, end))
 		return -EINVAL;
 
-	acpi_table_print_madt_entry(header);
+	acpi_table_print_madt_entry(&header->common);
 
 #ifdef CONFIG_X86_X2APIC
 	apic_id = processor->local_apic_id;
@@ -242,7 +242,7 @@
 }
 
 static int __init
-acpi_parse_lapic(struct acpi_subtable_header * header, const unsigned long end)
+acpi_parse_lapic(union acpi_subtable_headers * header, const unsigned long end)
 {
 	struct acpi_madt_local_apic *processor = NULL;
 
@@ -251,7 +251,7 @@
 	if (BAD_MADT_ENTRY(processor, end))
 		return -EINVAL;
 
-	acpi_table_print_madt_entry(header);
+	acpi_table_print_madt_entry(&header->common);
 
 	/* Ignore invalid ID */
 	if (processor->id == 0xff)
@@ -272,7 +272,7 @@
 }
 
 static int __init
-acpi_parse_sapic(struct acpi_subtable_header *header, const unsigned long end)
+acpi_parse_sapic(union acpi_subtable_headers *header, const unsigned long end)
 {
 	struct acpi_madt_local_sapic *processor = NULL;
 
@@ -281,7 +281,7 @@
 	if (BAD_MADT_ENTRY(processor, end))
 		return -EINVAL;
 
-	acpi_table_print_madt_entry(header);
+	acpi_table_print_madt_entry(&header->common);
 
 	acpi_register_lapic((processor->id << 8) | processor->eid,/* APIC ID */
 			    processor->processor_id, /* ACPI ID */
@@ -291,7 +291,7 @@
 }
 
 static int __init
-acpi_parse_lapic_addr_ovr(struct acpi_subtable_header * header,
+acpi_parse_lapic_addr_ovr(union acpi_subtable_headers * header,
 			  const unsigned long end)
 {
 	struct acpi_madt_local_apic_override *lapic_addr_ovr = NULL;
@@ -301,7 +301,7 @@
 	if (BAD_MADT_ENTRY(lapic_addr_ovr, end))
 		return -EINVAL;
 
-	acpi_table_print_madt_entry(header);
+	acpi_table_print_madt_entry(&header->common);
 
 	acpi_lapic_addr = lapic_addr_ovr->address;
 
@@ -309,7 +309,7 @@
 }
 
 static int __init
-acpi_parse_x2apic_nmi(struct acpi_subtable_header *header,
+acpi_parse_x2apic_nmi(union acpi_subtable_headers *header,
 		      const unsigned long end)
 {
 	struct acpi_madt_local_x2apic_nmi *x2apic_nmi = NULL;
@@ -319,7 +319,7 @@
 	if (BAD_MADT_ENTRY(x2apic_nmi, end))
 		return -EINVAL;
 
-	acpi_table_print_madt_entry(header);
+	acpi_table_print_madt_entry(&header->common);
 
 	if (x2apic_nmi->lint != 1)
 		printk(KERN_WARNING PREFIX "NMI not connected to LINT 1!\n");
@@ -328,7 +328,7 @@
 }
 
 static int __init
-acpi_parse_lapic_nmi(struct acpi_subtable_header * header, const unsigned long end)
+acpi_parse_lapic_nmi(union acpi_subtable_headers * header, const unsigned long end)
 {
 	struct acpi_madt_local_apic_nmi *lapic_nmi = NULL;
 
@@ -337,7 +337,7 @@
 	if (BAD_MADT_ENTRY(lapic_nmi, end))
 		return -EINVAL;
 
-	acpi_table_print_madt_entry(header);
+	acpi_table_print_madt_entry(&header->common);
 
 	if (lapic_nmi->lint != 1)
 		printk(KERN_WARNING PREFIX "NMI not connected to LINT 1!\n");
@@ -449,7 +449,7 @@
 }
 
 static int __init
-acpi_parse_ioapic(struct acpi_subtable_header * header, const unsigned long end)
+acpi_parse_ioapic(union acpi_subtable_headers * header, const unsigned long end)
 {
 	struct acpi_madt_io_apic *ioapic = NULL;
 	struct ioapic_domain_cfg cfg = {
@@ -462,7 +462,7 @@
 	if (BAD_MADT_ENTRY(ioapic, end))
 		return -EINVAL;
 
-	acpi_table_print_madt_entry(header);
+	acpi_table_print_madt_entry(&header->common);
 
 	/* Statically assign IRQ numbers for IOAPICs hosting legacy IRQs */
 	if (ioapic->global_irq_base < nr_legacy_irqs())
@@ -508,7 +508,7 @@
 }
 
 static int __init
-acpi_parse_int_src_ovr(struct acpi_subtable_header * header,
+acpi_parse_int_src_ovr(union acpi_subtable_headers * header,
 		       const unsigned long end)
 {
 	struct acpi_madt_interrupt_override *intsrc = NULL;
@@ -518,7 +518,7 @@
 	if (BAD_MADT_ENTRY(intsrc, end))
 		return -EINVAL;
 
-	acpi_table_print_madt_entry(header);
+	acpi_table_print_madt_entry(&header->common);
 
 	if (intsrc->source_irq == acpi_gbl_FADT.sci_interrupt) {
 		acpi_sci_ioapic_setup(intsrc->source_irq,
@@ -550,7 +550,7 @@
 }
 
 static int __init
-acpi_parse_nmi_src(struct acpi_subtable_header * header, const unsigned long end)
+acpi_parse_nmi_src(union acpi_subtable_headers * header, const unsigned long end)
 {
 	struct acpi_madt_nmi_source *nmi_src = NULL;
 
@@ -559,7 +559,7 @@
 	if (BAD_MADT_ENTRY(nmi_src, end))
 		return -EINVAL;
 
-	acpi_table_print_madt_entry(header);
+	acpi_table_print_madt_entry(&header->common);
 
 	/* TBD: Support nimsrc entries? */
 
diff --git a/drivers/acpi/numa.c b/drivers/acpi/numa.c
index 867f6e3..3099583 100644
--- a/drivers/acpi/numa.c
+++ b/drivers/acpi/numa.c
@@ -339,7 +339,7 @@
 }
 
 static int __init
-acpi_parse_x2apic_affinity(struct acpi_subtable_header *header,
+acpi_parse_x2apic_affinity(union acpi_subtable_headers *header,
 			   const unsigned long end)
 {
 	struct acpi_srat_x2apic_cpu_affinity *processor_affinity;
@@ -348,7 +348,7 @@
 	if (!processor_affinity)
 		return -EINVAL;
 
-	acpi_table_print_srat_entry(header);
+	acpi_table_print_srat_entry(&header->common);
 
 	/* let architecture-dependent part to do it */
 	acpi_numa_x2apic_affinity_init(processor_affinity);
@@ -357,7 +357,7 @@
 }
 
 static int __init
-acpi_parse_processor_affinity(struct acpi_subtable_header *header,
+acpi_parse_processor_affinity(union acpi_subtable_headers *header,
 			      const unsigned long end)
 {
 	struct acpi_srat_cpu_affinity *processor_affinity;
@@ -366,7 +366,7 @@
 	if (!processor_affinity)
 		return -EINVAL;
 
-	acpi_table_print_srat_entry(header);
+	acpi_table_print_srat_entry(&header->common);
 
 	/* let architecture-dependent part to do it */
 	acpi_numa_processor_affinity_init(processor_affinity);
@@ -375,7 +375,7 @@
 }
 
 static int __init
-acpi_parse_gicc_affinity(struct acpi_subtable_header *header,
+acpi_parse_gicc_affinity(union acpi_subtable_headers *header,
 			 const unsigned long end)
 {
 	struct acpi_srat_gicc_affinity *processor_affinity;
@@ -384,7 +384,7 @@
 	if (!processor_affinity)
 		return -EINVAL;
 
-	acpi_table_print_srat_entry(header);
+	acpi_table_print_srat_entry(&header->common);
 
 	/* let architecture-dependent part to do it */
 	acpi_numa_gicc_affinity_init(processor_affinity);
@@ -395,7 +395,7 @@
 static int __initdata parsed_numa_memblks;
 
 static int __init
-acpi_parse_memory_affinity(struct acpi_subtable_header * header,
+acpi_parse_memory_affinity(union acpi_subtable_headers * header,
 			   const unsigned long end)
 {
 	struct acpi_srat_mem_affinity *memory_affinity;
@@ -404,7 +404,7 @@
 	if (!memory_affinity)
 		return -EINVAL;
 
-	acpi_table_print_srat_entry(header);
+	acpi_table_print_srat_entry(&header->common);
 
 	/* let architecture-dependent part to do it */
 	if (!acpi_numa_memory_affinity_init(memory_affinity))
diff --git a/drivers/acpi/scan.c b/drivers/acpi/scan.c
index 446c959..f7771a3 100644
--- a/drivers/acpi/scan.c
+++ b/drivers/acpi/scan.c
@@ -2241,10 +2241,10 @@
 static int acpi_probe_count;
 static DEFINE_MUTEX(acpi_probe_mutex);
 
-static int __init acpi_match_madt(struct acpi_subtable_header *header,
+static int __init acpi_match_madt(union acpi_subtable_headers *header,
 				  const unsigned long end)
 {
-	if (!ape->subtable_valid || ape->subtable_valid(header, ape))
+	if (!ape->subtable_valid || ape->subtable_valid(&header->common, ape))
 		if (!ape->probe_subtbl(header, end))
 			acpi_probe_count++;
 
diff --git a/drivers/acpi/tables.c b/drivers/acpi/tables.c
index 8fccbe4..7553774 100644
--- a/drivers/acpi/tables.c
+++ b/drivers/acpi/tables.c
@@ -49,6 +49,15 @@
 
 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 @@
 	}
 }
 
+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 @@
 		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 @@
 
 	/* 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 @@
 		 * 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) {
diff --git a/drivers/irqchip/irq-gic-v2m.c b/drivers/irqchip/irq-gic-v2m.c
index f5fe010..de14e06 100644
--- a/drivers/irqchip/irq-gic-v2m.c
+++ b/drivers/irqchip/irq-gic-v2m.c
@@ -446,7 +446,7 @@
 }
 
 static int __init
-acpi_parse_madt_msi(struct acpi_subtable_header *header,
+acpi_parse_madt_msi(union acpi_subtable_headers *header,
 		    const unsigned long end)
 {
 	int ret;
diff --git a/drivers/irqchip/irq-gic-v3-its-pci-msi.c b/drivers/irqchip/irq-gic-v3-its-pci-msi.c
index 8d6d009..c81d5b8 100644
--- a/drivers/irqchip/irq-gic-v3-its-pci-msi.c
+++ b/drivers/irqchip/irq-gic-v3-its-pci-msi.c
@@ -159,7 +159,7 @@
 #ifdef CONFIG_ACPI
 
 static int __init
-its_pci_msi_parse_madt(struct acpi_subtable_header *header,
+its_pci_msi_parse_madt(union acpi_subtable_headers *header,
 		       const unsigned long end)
 {
 	struct acpi_madt_generic_translator *its_entry;
diff --git a/drivers/irqchip/irq-gic-v3-its-platform-msi.c b/drivers/irqchip/irq-gic-v3-its-platform-msi.c
index 7b8e87b..9cdcda5b 100644
--- a/drivers/irqchip/irq-gic-v3-its-platform-msi.c
+++ b/drivers/irqchip/irq-gic-v3-its-platform-msi.c
@@ -117,7 +117,7 @@
 
 #ifdef CONFIG_ACPI
 static int __init
-its_pmsi_parse_madt(struct acpi_subtable_header *header,
+its_pmsi_parse_madt(union acpi_subtable_headers *header,
 			const unsigned long end)
 {
 	struct acpi_madt_generic_translator *its_entry;
diff --git a/drivers/irqchip/irq-gic-v3-its.c b/drivers/irqchip/irq-gic-v3-its.c
index 7577755..128ac89 100644
--- a/drivers/irqchip/irq-gic-v3-its.c
+++ b/drivers/irqchip/irq-gic-v3-its.c
@@ -3830,13 +3830,13 @@
 	return NUMA_NO_NODE;
 }
 
-static int __init gic_acpi_match_srat_its(struct acpi_subtable_header *header,
+static int __init gic_acpi_match_srat_its(union acpi_subtable_headers *header,
 					  const unsigned long end)
 {
 	return 0;
 }
 
-static int __init gic_acpi_parse_srat_its(struct acpi_subtable_header *header,
+static int __init gic_acpi_parse_srat_its(union acpi_subtable_headers *header,
 			 const unsigned long end)
 {
 	int node;
@@ -3903,7 +3903,7 @@
 static void __init acpi_its_srat_maps_free(void) { }
 #endif
 
-static int __init gic_acpi_parse_madt_its(struct acpi_subtable_header *header,
+static int __init gic_acpi_parse_madt_its(union acpi_subtable_headers *header,
 					  const unsigned long end)
 {
 	struct acpi_madt_generic_translator *its_entry;
diff --git a/drivers/irqchip/irq-gic-v3.c b/drivers/irqchip/irq-gic-v3.c
index 15e55d3..f44cd89 100644
--- a/drivers/irqchip/irq-gic-v3.c
+++ b/drivers/irqchip/irq-gic-v3.c
@@ -1593,7 +1593,7 @@
 }
 
 static int __init
-gic_acpi_parse_madt_redist(struct acpi_subtable_header *header,
+gic_acpi_parse_madt_redist(union acpi_subtable_headers *header,
 			   const unsigned long end)
 {
 	struct acpi_madt_generic_redistributor *redist =
@@ -1611,7 +1611,7 @@
 }
 
 static int __init
-gic_acpi_parse_madt_gicc(struct acpi_subtable_header *header,
+gic_acpi_parse_madt_gicc(union acpi_subtable_headers *header,
 			 const unsigned long end)
 {
 	struct acpi_madt_generic_interrupt *gicc =
@@ -1653,14 +1653,14 @@
 	return -ENODEV;
 }
 
-static int __init gic_acpi_match_gicr(struct acpi_subtable_header *header,
+static int __init gic_acpi_match_gicr(union acpi_subtable_headers *header,
 				  const unsigned long end)
 {
 	/* Subtable presence means that redist exists, that's it */
 	return 0;
 }
 
-static int __init gic_acpi_match_gicc(struct acpi_subtable_header *header,
+static int __init gic_acpi_match_gicc(union acpi_subtable_headers *header,
 				      const unsigned long end)
 {
 	struct acpi_madt_generic_interrupt *gicc =
@@ -1726,7 +1726,7 @@
 	return true;
 }
 
-static int __init gic_acpi_parse_virt_madt_gicc(struct acpi_subtable_header *header,
+static int __init gic_acpi_parse_virt_madt_gicc(union acpi_subtable_headers *header,
 						const unsigned long end)
 {
 	struct acpi_madt_generic_interrupt *gicc =
diff --git a/drivers/irqchip/irq-gic.c b/drivers/irqchip/irq-gic.c
index fd3110c..c6dbe50 100644
--- a/drivers/irqchip/irq-gic.c
+++ b/drivers/irqchip/irq-gic.c
@@ -1495,7 +1495,7 @@
 } acpi_data __initdata;
 
 static int __init
-gic_acpi_parse_madt_cpu(struct acpi_subtable_header *header,
+gic_acpi_parse_madt_cpu(union acpi_subtable_headers *header,
 			const unsigned long end)
 {
 	struct acpi_madt_generic_interrupt *processor;
@@ -1527,7 +1527,7 @@
 }
 
 /* The things you have to do to just *count* something... */
-static int __init acpi_dummy_func(struct acpi_subtable_header *header,
+static int __init acpi_dummy_func(union acpi_subtable_headers *header,
 				  const unsigned long end)
 {
 	return 0;
diff --git a/drivers/mailbox/pcc.c b/drivers/mailbox/pcc.c
index 256f18b..08a0a35 100644
--- a/drivers/mailbox/pcc.c
+++ b/drivers/mailbox/pcc.c
@@ -382,7 +382,7 @@
  *
  * This gets called for each entry in the PCC table.
  */
-static int parse_pcc_subspace(struct acpi_subtable_header *header,
+static int parse_pcc_subspace(union acpi_subtable_headers *header,
 		const unsigned long end)
 {
 	struct acpi_pcct_subspace *ss = (struct acpi_pcct_subspace *) header;
diff --git a/include/linux/acpi.h b/include/linux/acpi.h
index d5dcebd..9494d42b 100644
--- a/include/linux/acpi.h
+++ b/include/linux/acpi.h
@@ -141,10 +141,13 @@
 
 
 /* Table Handlers */
+union acpi_subtable_headers {
+	struct acpi_subtable_header common;
+};
 
 typedef int (*acpi_tbl_table_handler)(struct acpi_table_header *table);
 
-typedef int (*acpi_tbl_entry_handler)(struct acpi_subtable_header *header,
+typedef int (*acpi_tbl_entry_handler)(union acpi_subtable_headers *header,
 				      const unsigned long end);
 
 /* Debugger support */