On 09/09/15 20:57, Al Stone wrote:
On 09/07/2015 09:32 AM, Sudeep Holla wrote:
Hi Al,
On 19/08/15 23:07, Al Stone wrote:
I finally got a chance to try this series on Juno. Well it exposed a firmware
bug in MADT table :)
[..]
acpi_tbl_entry_handler handler,
@@ -245,6 +484,8 @@ acpi_parse_entries(char *id, unsigned long table_size,
table_end) {
if (entry->type == entry_id
&& (!max_entries || count < max_entries)) {
+ if (bad_madt_entry(table_header, entry))
+ return -EINVAL;
Not sure if we can have the above check here unconditionally.
Currently I can see there are 2 other users of acpi_parse_entries i.e.
PCC and NUMA. So may be it can be made conditional or return success for
non-MADT tables from bad_madt_entry ?
So, I went back and double checked the other users and they're looking at
the return value for acpi_parse_entries properly; adding in the check above
unconditionally should not cause any behavior change.
I disagree. I populated PCCT table on Juno to get this error for
PCCT(PCCT header gets interpreted as MADT header):
"
ACPI: undefined version for either FADT 5.1 or MADT 1
Error parsing PCC subspaces from PCCT
"
And here the stacktrace:
[<ffffffc000881e58>] bad_madt_entry+0x90/0x16c
[<ffffffc000882030>] acpi_table_parse_entries+0xfc/0x180
[<ffffffc000895af8>] pcc_init+0x70/0x148
Further, despite the name, acpi_parse_entries is only used to examine MADT
subtables. Granted, we should probably make the name clearer at some point
(too ambiguous as to which entries are parsed right now). Nonetheless, current
usage seems to be in order.
From the code inspection, I can see we have 3 users of
acpi_parse_entries not just MADT but also PCC and NUMA/SRAT
Something like this solves this issue:
- if (bad_madt_entry(table_header, entry))
+ if (!strncmp(id, ACPI_SIG_MADT, 4) &&
+ bad_madt_entry(table_header, entry)
Or am I still missing something ?
Regards,
Sudeep
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