[PATCH v8 5/8] arm: armv8: save boot arguments

[Ilias Apalodimas]

On Sat, 3 Feb 2024 at 18:38, Raymond Mao <raymond.mao at linaro.org> wrote:
>
> Save boot arguments x[0-3] into an array for handover of bloblist from
> previous boot stage.
>
> Signed-off-by: Raymond Mao <raymond.mao at linaro.org>
> Suggested-by: Ard Biesheuvel <ardb at kernel.org>
> ---
> Changes in v2
> - New patch file created for v2.
> Changes in V5
> - Drop the dependence on OF_BOARD.
> Changes in V7
> - Exclude the saved_args when BLOBLIST is disabled.
> Changes in V8
> - Use PC-relative reference for saved_args.
> - Add 4-byte alignment for saved_args.
>
>  arch/arm/cpu/armv8/start.S | 23 +++++++++++++++++++++++
>  1 file changed, 23 insertions(+)
>
> diff --git a/arch/arm/cpu/armv8/start.S b/arch/arm/cpu/armv8/start.S
> index 6cc1d26e5e..7461280261 100644
> --- a/arch/arm/cpu/armv8/start.S
> +++ b/arch/arm/cpu/armv8/start.S
> @@ -370,5 +370,28 @@ ENTRY(c_runtime_cpu_setup)
>  ENDPROC(c_runtime_cpu_setup)
>
>  WEAK(save_boot_params)
> +#if (IS_ENABLED(CONFIG_BLOBLIST))
> +       /* Calculate the PC-relative address of saved_args */
> +       adr     x9, saved_args_offset
> +       ldr     w10, saved_args_offset
> +       add     x9, x9, w10, sxtw
> +
> +       stp     x0, x1, [x9]
> +       stp     x2, x3, [x9, #16]
> +#endif
>         b       save_boot_params_ret    /* back to my caller */
>  ENDPROC(save_boot_params)
> +
> +#if (IS_ENABLED(CONFIG_BLOBLIST))
> +saved_args_offset:
> +       .long   saved_args - .  /* offset from current code to save_args */
> +
> +       .section .data
> +       .align 2
> +       .global saved_args
> +saved_args:
> +       .rept 4
> +       .dword 0
> +       .endr
> +END(saved_args)
> +#endif
> --
> 2.25.1
>

 Reviewed-by: Ilias Apalodimas <ilias.apalodimas at linaro.org>