Re: [kvm-unit-tests PATCH v3 03/27] lib: Ensure all struct definition for ACPI tables are packed

Andrew Jones
2022-07-01T09:35:50Z

On Thu, Jun 30, 2022 at 11:03:00AM +0100, Nikos Nikoleris wrote:
> All ACPI table definitions are provided with precise definitions of
> field sizes and offsets, make sure that no compiler optimization can
> interfere with the memory layout of the corresponding structs.
>
> Signed-off-by: Nikos Nikoleris <nikos.nikoleris@arm.com>
> ---
> lib/acpi.h | 8 ++++++++
> 1 file changed, 8 insertions(+)
>
> diff --git a/lib/acpi.h b/lib/acpi.h
> index 456e62d..b853a55 100644
> --- a/lib/acpi.h
> +++ b/lib/acpi.h
> @@ -3,6 +3,12 @@
>
> #include "libcflat.h"
>
> +/*
> + * All tables and structures must be byte-packed to match the ACPI
> + * specification, since the tables are provided by the system BIOS
> + */
> +#pragma pack(1)
> +
> #define ACPI_SIGNATURE(c1, c2, c3, c4) \
> ((c1) | ((c2) << 8) | ((c3) << 16) | ((c4) << 24))
>
> @@ -106,6 +112,8 @@ struct facs_descriptor_rev1
> u8 reserved3 [40]; /* Reserved - must be zero */
> };
>
> +#pragma pack(0)
> +
> void set_efi_rsdp(struct rsdp_descriptor *rsdp);
> void* find_acpi_table_addr(u32 sig);
>
> --
> 2.25.1
>

Reviewed-by: Andrew Jones <andrew.jones@linux.dev>