From: Jean Delvare <jdelvare@xxxxxxx>
[ Upstream commit c9aba14362a6eec583819ec8f4b872c1816f5cbe ]
Since version 3.0.0 of the SMBIOS specification, there can be
multiple entry points in memory, pointing to one or two DMI tables.
If both a 32-bit ("_SM_") entry point and a 64-bit ("_SM3_") entry
point are present, the specification requires that the latter points
to a table which is a super-set of the table pointed to by the
former. Therefore we should give preference to the 64-bit ("_SM3_")
entry point.
However, currently the code is picking the first valid entry point
it finds. Per specification, we should look for a 64-bit ("_SM3_")
entry point first, and if we can't find any, look for a 32-bit
("_SM_" or "_DMI_") entry point. Modify the code to do that.
Signed-off-by: Jean Delvare <jdelvare@xxxxxxx>
Signed-off-by: Sasha Levin <alexander.levin@xxxxxxxxxxxxx>
---
drivers/firmware/dmi_scan.c | 17 ++++++++++++++++-
1 file changed, 16 insertions(+), 1 deletion(-)
diff --git a/drivers/firmware/dmi_scan.c b/drivers/firmware/dmi_scan.c
index 0e08e665f715..f1d4881dd2fc 100644
--- a/drivers/firmware/dmi_scan.c
+++ b/drivers/firmware/dmi_scan.c
@@ -626,6 +626,21 @@ void __init dmi_scan_machine(void)
if (p == NULL)
goto error;
+ /*
+ * Same logic as above, look for a 64-bit entry point
+ * first, and if not found, fall back to 32-bit entry point.
+ */
+ memcpy_fromio(buf, p, 16);
+ for (q = p + 16; q < p + 0x10000; q += 16) {
+ memcpy_fromio(buf + 16, q, 16);
+ if (!dmi_smbios3_present(buf)) {
+ dmi_available = 1;
+ dmi_early_unmap(p, 0x10000);
+ goto out;
+ }
+ memcpy(buf, buf + 16, 16);
+ }
+
/*
* Iterate over all possible DMI header addresses q.
* Maintain the 32 bytes around q in buf. On the
@@ -636,7 +651,7 @@ void __init dmi_scan_machine(void)
memset(buf, 0, 16);
for (q = p; q < p + 0x10000; q += 16) {
memcpy_fromio(buf + 16, q, 16);
- if (!dmi_smbios3_present(buf) || !dmi_present(buf)) {
+ if (!dmi_present(buf)) {
dmi_available = 1;
dmi_early_unmap(p, 0x10000);
goto out;
--
2.15.1