[PATCH] bloblist: Fix bloblist convention checking.

[Raymond Mao]

Hi Levi,

On Tue, 9 Jul 2024 at 09:25, Levi Yun <yeoreum.yun at arm.com> wrote:

> According to recently firmware handsoff spec [1]'s
> "Register usage at handoff boundary",
> Transfer List's signature value was changed from 0x40_b10b
> (3 bytes) to 4a0f_b10b (4 bytes).
>
> As updating of TL's signature, register value of x1/r1 should be:
>
> In aarch32's r1 value should be
>     R1[23:0]: TL signature (4a0f_b10b->masked range value: 0f_b10b)
>     R1[31:24]: version of the register convention ==  1
>
> and
>
> In aarch64's x1 value should be
>     X1[31:0]: TL signature (4a0f_b10b)
>     X1[39:32]: version of the register convention ==  1
>     X1[63:40]: MBZ
> (See the [2] and [3]).
>
> Also, according to architecture, the convention is slight different:
>
> In aarch32:
>     R0: MBZ
>     R1: see above
>     R2: Compatibility location for passing a platform description
> devicetree
>     R3: tl_base_pa
>
> In aarch64:
>     X0: Compatibility location for passing a platform description
> devicetree
>     X1: see above
>     X2: MBZ
>     X3: tl_base_pa
>
> This patch fix problems:
>    1. breaking X1 value with updated specification in aarch64
>         - change of length of signature field.
>
>    2. previous error value set in R1 in arm32.
>         - length of signature should be 24, but it uses 32bit signature.
>
>    3. according to architecture, check register convetion differently.
>
> [1] https://github.com/FirmwareHandoff/firmware_handoff
> [2] https://github.com/FirmwareHandoff/firmware_handoff/issues/32
> [3]
> https://github.com/FirmwareHandoff/firmware_handoff/commit/5aa7aa1d3a1db75213e458d392b751f0707de027
>
> Signed-off-by: Levi Yun <yeoreum.yun at arm.com>
> ---
>  arch/arm/lib/xferlist.c |  8 +++++---
>  common/bloblist.c       | 11 ++++++++++-
>  include/bloblist.h      |  5 ++++-
>  3 files changed, 19 insertions(+), 5 deletions(-)
>
> diff --git a/arch/arm/lib/xferlist.c b/arch/arm/lib/xferlist.c
> index f9c5d88bd4..a6349293bd 100644
> --- a/arch/arm/lib/xferlist.c
> +++ b/arch/arm/lib/xferlist.c
> @@ -12,12 +12,14 @@ int xferlist_from_boot_arg(ulong addr, ulong size)
>  {
>         int ret;
>
> -       ret = bloblist_check(saved_args[3], size);
> +       if (IS_ENABLED(CONFIG_64BIT))
> +               ret = bloblist_check_reg_conv(saved_args[0],
> saved_args[2], saved_args[1]);
> +       else
> +               ret = bloblist_check_reg_conv(saved_args[2],
> saved_args[0], saved_args[1]);
>

The handoff of armv7 will break if you swap arg[0] and arg[2] here.
The args are already aligned in the correct order via the assembly code.
Please see the 'save_boot_params' function in start.S of armv7.

Regards,
Raymond