[PATCH 1/1] acpi: cannot have RSDT above 4 GiB

[Simon Glass]

Hi Heinrich,

On Sat, 11 Nov 2023 at 07:28, Heinrich Schuchardt
<heinrich.schuchardt at canonical.com> wrote:
>
> The field RsdtAddress has only 32 bit. The RSDT table cannot be located
> beyond 4 GiB.
>
> Signed-off-by: Heinrich Schuchardt <heinrich.schuchardt at canonical.com>
> ---
>  lib/acpi/base.c | 26 +++++++++++++++++++-------
>  1 file changed, 19 insertions(+), 7 deletions(-)

Reviewed-by: Simon Glass <sjg at chromium.org>

nits / question below

>
> diff --git a/lib/acpi/base.c b/lib/acpi/base.c
> index 2057bd2bef..128a76ad39 100644
> --- a/lib/acpi/base.c
> +++ b/lib/acpi/base.c
> @@ -21,10 +21,17 @@ void acpi_write_rsdp(struct acpi_rsdp *rsdp, struct acpi_rsdt *rsdt,
>         memcpy(rsdp->signature, RSDP_SIG, 8);
>         memcpy(rsdp->oem_id, OEM_ID, 6);
>
> -       rsdp->length = sizeof(struct acpi_rsdp);
> -       rsdp->rsdt_address = map_to_sysmem(rsdt);
> +       if (rsdt)
> +               rsdp->rsdt_address = map_to_sysmem(rsdt);
> +       else
> +               rsdp->rsdt_address = 0;

There is a memset() at the top so this line (and the one below) should
not be needed.

> +
> +       if (xsdt)
> +               rsdp->xsdt_address = map_to_sysmem(xsdt);
> +       else
> +               rsdp->xsdt_address = 0;
>
> -       rsdp->xsdt_address = map_to_sysmem(xsdt);
> +       rsdp->length = sizeof(struct acpi_rsdp);
>         rsdp->revision = ACPI_RSDP_REV_ACPI_2_0;
>
>         /* Calculate checksums */
> @@ -68,11 +75,15 @@ static void acpi_write_xsdt(struct acpi_xsdt *xsdt)
>  static int acpi_write_base(struct acpi_ctx *ctx,
>                            const struct acpi_writer *entry)
>  {
> -       /* We need at least an RSDP and an RSDT Table */
> +       /* We need at least an RSDP and an XSDT Table */
>         ctx->rsdp = ctx->current;
>         acpi_inc_align(ctx, sizeof(struct acpi_rsdp));
> -       ctx->rsdt = ctx->current;
> -       acpi_inc_align(ctx, sizeof(struct acpi_rsdt));
> +       if (map_to_sysmem(ctx->current) < UINT_MAX - 0x10000) {

Won't that do something different on 64-bit machines? It seems that
you want to check against SZ_4G ?

> +               ctx->rsdt = ctx->current;
> +               acpi_inc_align(ctx, sizeof(struct acpi_rsdt));
> +       } else {
> +               ctx->rsdt = 0;
> +       }
>         ctx->xsdt = ctx->current;
>         acpi_inc_align(ctx, sizeof(struct acpi_xsdt));
>
> @@ -80,7 +91,8 @@ static int acpi_write_base(struct acpi_ctx *ctx,
>         memset(ctx->base, '\0', ctx->current - ctx->base);
>
>         acpi_write_rsdp(ctx->rsdp, ctx->rsdt, ctx->xsdt);
> -       acpi_write_rsdt(ctx->rsdt);
> +       if (ctx->rsdt)
> +               acpi_write_rsdt(ctx->rsdt);
>         acpi_write_xsdt(ctx->xsdt);
>
>         return 0;
> --
> 2.40.1
>

Regards,
Simon