Messages in this thread | | | Subject | Re: [PATCH v2 1/5] ACPI: add in a bad_madt_entry() function to eventually replace the macro | From | Sudeep Holla <> | Date | Thu, 10 Sep 2015 17:20:20 +0100 |
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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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