Re: [PATCH v3 2/3] ACPI / ARM64: add BAD_MADT_GICC_ENTRY() macro

Catalin Marinas
2015-07-03T14:06:12Z

On Thu, Jul 02, 2015 at 05:48:35PM -0600, Al Stone wrote:
> diff --git a/arch/arm64/include/asm/acpi.h b/arch/arm64/include/asm/acpi.h
> index 39248d3..a3c26a4 100644
> --- a/arch/arm64/include/asm/acpi.h
> +++ b/arch/arm64/include/asm/acpi.h
> @@ -19,6 +19,17 @@
> #include <asm/psci.h>
> #include <asm/smp_plat.h>
>
> +/* Macros for consistency checks of the GICC subtable of MADT */
> +#define ACPI_MADT_GICC_51_LENGTH 76
> +#define ACPI_MADT_GICC_60_LENGTH 80
> +
> +#define BAD_MADT_GICC_ENTRY(entry, end) ( \
> + (!entry) || (unsigned long)entry + sizeof(*entry) > end || \
> + ((ACPI_FADT_SPEC_VERSION == ACPI_FADT_SPEC_VERSION_51) && \
> + (entry->header.length != ACPI_MADT_GICC_51_LENGTH)) || \
> + ((ACPI_FADT_SPEC_VERSION == ACPI_FADT_SPEC_VERSION_60) && \
> + (entry->header.length != ACPI_MADT_GICC_60_LENGTH)))

This looks ugly but, well, we could live with this.

However, I'd like to avoid having to extend this macro every time we get
a new spec released, like 6.1 defining another 80 or 84 etc. So, how
about we only update this when there is an actual change in the length?
Something like:

#define ACPI_MADT_GICC_LENGTH ({ \
u8 length; \
if (ACPI_FADT_SPEC_VERSION < ACPI_FADT_SPEC_VERSION_6_0) \
length = 76; \
else \
length = 80; \
length; \
})

or just:

#define ACPI_MADT_GICC_LENGTH \
(ACPI_FADT_SPEC_VERSION < ACPI_FADT_SPEC_VERSION_6_0 ? 76 : 80)

(the latter is simpler but may not look nice if we change it again in
6.1; though we could re-write this macro when needed, not a problem)

--
Catalin