On 07/07/2015 07:31 AM, Catalin Marinas wrote:
On Tue, Jul 07, 2015 at 01:20:51AM +0200, Rafael J. Wysocki wrote:
On Tue, Jul 7, 2015 at 1:16 AM, Al Stone al.stone@linaro.org wrote:
In the ACPI 5.1 version of the spec, the struct for the GICC subtable (struct acpi_madt_generic_interrupt) of the MADT is 76 bytes long; in ACPI 6.0, the struct is 80 bytes long. But, there is only one definition in ACPICA for this struct -- and that is the 6.0 version. Hence, when BAD_MADT_ENTRY() compares the struct size to the length in the GICC subtable, it fails if 5.1 structs are in use, and there are systems in the wild that have them.
Note that this was found in linux-next and these patches apply against that tree and the arm64 kernel tree; 4.1 does not appear to have this problem since it still has the 5.1 struct definition.
Though there is precedent in ia64 code for ignoring the changes in size, this patch set instead verifies correctness. The first patch adds the BAD_MADT_GICC_ENTRY() macro to check the GICC subtable only, accounting for the difference in specification versions that are possible. The second patch replaces BAD_MADT_ENTRY usage with the BAD_MADT_GICC_ENTRY macro in arm64 code, which is currently the only architecture affected. The BAD_MADT_ENTRY() will continue to work as is for all other MADT subtables.
I have tested these patches on an APM Mustang with version 1.15 firmware, where the problem was found, and they fix the problem -- i.e., the system will boot with either Linux 4.1 or linux-next kernels using the same ACPI 5.1 compatible firmware.
ACK for the series, but I guess it's better to let it go via ARM64, right?
Fine by me. I'll pick them up for 4.2-rc2.
Thanks.
Thanks, Catalin. Holler if there's any problems.