[PATCH v2 2/3] ACPI: add BAD_MADT_GICC_ENTRY() macro

[al.stone@linaro.org (Al Stone)]

The BAD_MADT_ENTRY() macro is designed to work for all of the subtables
of the MADT.  In the ACPI 5.1 version of the spec, the struct for the
GICC subtable (struct acpi_madt_generic_interrupt) is 76 bytes long; in
ACPI 6.0, the struct is 80 bytes long.  But, there is only one definition
in ACPICA for this struct -- and that is the 6.0 version.  Hence, when
BAD_MADT_ENTRY() compares the struct size to the length in the GICC
subtable, it fails if 5.1 structs are in use, and there are systems in
the wild that have them.

This patch adds the BAD_MADT_GICC_ENTRY() that checks the GICC subtable
only, accounting for the difference in specification versions that are
possible.  The BAD_MADT_ENTRY() will continue to work as is for all other
MADT subtables.

Signed-off-by: Al Stone <al.stone@linaro.org>
---
 include/linux/acpi.h | 10 ++++++++++
 1 file changed, 10 insertions(+)

diff --git a/include/linux/acpi.h b/include/linux/acpi.h
index 33ed313..d3a1758 100644
--- a/include/linux/acpi.h
+++ b/include/linux/acpi.h
@@ -127,6 +127,16 @@ static inline void acpi_initrd_override(void *data, size_t size)
 		(!entry) || (unsigned long)entry + sizeof(*entry) > end ||  \
 		((struct acpi_subtable_header *)entry)->length < sizeof(*entry))
 
+#define ACPI_MADT_GICC_51_LENGTH	76
+#define ACPI_MADT_GICC_60_LENGTH	80
+
+#define BAD_MADT_GICC_ENTRY(entry, end) (				    \
+		(!entry) || (unsigned long)entry + sizeof(*entry) > end ||  \
+		((ACPI_FADT_SPEC_VERSION == ACPI_SPEC_VERSION(5, 1)) &&	    \
+		 (entry->header.length != ACPI_MADT_GICC_51_LENGTH))	||  \
+		((ACPI_FADT_SPEC_VERSION == ACPI_SPEC_VERSION(6, 0)) &&	    \
+		 (entry->header.length != ACPI_MADT_GICC_60_LENGTH)))
+
 char * __acpi_map_table (unsigned long phys_addr, unsigned long size);
 void __acpi_unmap_table(char *map, unsigned long size);
 int early_acpi_boot_init(void);
-- 
2.4.0