ACK: [PATCH] acpi/fadt: reject 5.0 tables with ARM specific attributes set

[Colin Ian King]

On 20/02/2019 11:59, Ard Biesheuvel wrote:
> In ACPI 5.1, two reserved FADT fields were put to use, and renamed
> to minor_version and arm_boot_flags, respectively. So compliant FADT
> tables should either have a zero value in both fields, or have a
> minor_version of at least 1 if the arm_boot_flags field is non-zero.
> 
> Since ACPI 5.1 is the lowest version of the spec that actually reasons
> about ARM systems at all, the Linux arm64 ACPI layer rejects 5.0 or
> earlier implementations of the FADT. However, FADT implementations have
> been observed in the wild that do define all the ARM specific pieces
> that did not exist in ACPI 5.0, but still keep the minor_version field
> at zero. So let's flag these implementations by only permitting a
> non-zero value of arm_boot_flags if the minor_version is >=1.
> 
> Signed-off-by: Ard Biesheuvel <ard.biesheuvel at linaro.org>
> ---
>  src/acpi/fadt/fadt.c | 7 +++++++
>  1 file changed, 7 insertions(+)
> 
> diff --git a/src/acpi/fadt/fadt.c b/src/acpi/fadt/fadt.c
> index 14db51acda51..d7d6e3b862d1 100644
> --- a/src/acpi/fadt/fadt.c
> +++ b/src/acpi/fadt/fadt.c
> @@ -412,6 +412,13 @@ static void acpi_table_check_fadt_reserved(fwts_framework *fw)
>  		fwts_failed(fw, LOG_LEVEL_MEDIUM, "FADTReservedZero",
>  			    "FADT second reserved field is not zero: 0x%02x",
>  			    fadt->reserved1);
> +
> +	if (fadt->header.revision == 5 &&
> +	    fadt->minor_version == 0 &&
> +	    fadt->arm_boot_flags != 0)
> +		fwts_failed(fw, LOG_LEVEL_MEDIUM, "FADTReservedZero",
> +			    "FADT 5.0 reserved field 'arm_boot_flags' is not zero: 0x%04x",
> +			    fadt->arm_boot_flags);
>  }
>  
>  static void acpi_table_check_fadt_pm_profile(fwts_framework *fw)
> 

Thanks for this fix.

Acked-by: Colin Ian King <colin.king at canonical.com>