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firmware: dmi_scan: Look for SMBIOS 3 entry point first 

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@suse.de>
This commit is contained in:
Jean Delvare 2017-06-15 13:46:00 +02:00
parent 3c2993b8c6
commit c9aba14362
1 changed files with 16 additions and 1 deletions
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17
drivers/firmware/dmi_scan.c
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@ -649,6 +649,21 @@ 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
@ -659,7 +674,7 @@ 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;