smbios: Calculate SMBIOS Max Struct size

The SMBIOS Specification 2.3 and up defines Maximum Structure Size
as the "Size of the largest SMBIOS structure, in bytes, and encompasses
the structure’s formatted area and text strings." The hardcoded size
is too small to accurately represent the maximum SMBIOS structure sizes.
While the field is not used by Linux it is used by some RTOS
implementations, eg. VxWorks.

TEST=Booted Linux and ran github.com/bfrisch/dmidecode which verified
the maximum structure size on Minnowboard Max.
Change-Id: I98087975c53a02857742dea283f4e303485b2ffe
Signed-off-by: Ben Frisch <bfrisch@gmail.com>
Reviewed-on: http://review.coreboot.org/10163
Tested-by: build bot (Jenkins)
Reviewed-by: Paul Menzel <paulepanter@users.sourceforge.net>
Reviewed-by: Patrick Georgi <pgeorgi@google.com>

1 files changed, 16 insertions, 13 deletions

diff --git a/src/arch/x86/boot/smbios.c b/src/arch/x86/boot/smbios.c
index 1dbe32dc2d..fc5ac6634f 100644
--- a/src/arch/x86/boot/smbios.c
+++ b/src/arch/x86/boot/smbios.c
@@ -529,11 +529,14 @@ static int smbios_walk_device_tree(struct device *tree, int *handle, unsigned lo
 	return len;
 }
 
+#define update_max(len, max_len, stmt) do { int tmp = stmt; max_len = MAX(max_len, tmp); len += tmp; } while(0)
 unsigned long smbios_write_tables(unsigned long current)
 {
 	struct smbios_entry *se;
 	unsigned long tables;
-	int len, handle = 0;
+	int len = 0;
+	int max_struct_size = 0;
+	int handle = 0;
 
 	current = ALIGN(current, 16);
 	printk(BIOS_DEBUG, "%s: %08lx\n", __func__, current);
@@ -543,28 +546,28 @@ unsigned long smbios_write_tables(unsigned long current)
 	current = ALIGN(current, 16);
 
 	tables = current;
-	len = smbios_write_type0(&current, handle++);
-	len += smbios_write_type1(&current, handle++);
-	len += smbios_write_type2(&current, handle++);
-	len += smbios_write_type3(&current, handle++);
-	len += smbios_write_type4(&current, handle++);
-	len += smbios_write_type11(&current, &handle);
+	update_max(len, max_struct_size, smbios_write_type0(&current, handle++));
+	update_max(len, max_struct_size, smbios_write_type1(&current, handle++));
+	update_max(len, max_struct_size, smbios_write_type2(&current, handle++));
+	update_max(len, max_struct_size, smbios_write_type3(&current, handle++));
+	update_max(len, max_struct_size, smbios_write_type4(&current, handle++));
+	update_max(len, max_struct_size, smbios_write_type11(&current, &handle));
 #if CONFIG_ELOG
-	len += elog_smbios_write_type15(&current, handle++);
+	update_max(len, max_struct_size, smbios_write_type15(&current, &handle));
 #endif
-	len += smbios_write_type17(&current, &handle);
-	len += smbios_write_type32(&current, handle++);
+	update_max(len, max_struct_size, smbios_write_type17(&current, &handle));
+	update_max(len, max_struct_size, smbios_write_type32(&current, handle++));
 
-	len += smbios_walk_device_tree(all_devices, &handle, &current);
+	update_max(len, max_struct_size, smbios_walk_device_tree(all_devices, &handle, &current));
 
-	len += smbios_write_type127(&current, handle++);
+	update_max(len, max_struct_size, smbios_write_type127(&current, handle++));
 
 	memset(se, 0, sizeof(struct smbios_entry));
 	memcpy(se->anchor, "_SM_", 4);
 	se->length = sizeof(struct smbios_entry);
 	se->major_version = 2;
 	se->minor_version = 7;
-	se->max_struct_size = 24;
+	se->max_struct_size = max_struct_size;
 	se->struct_count = handle;
 	memcpy(se->intermediate_anchor_string, "_DMI_", 5);