linux-kernel - Re: [PATCH 2/2] arm64: efi: Pass reboot cmd parameter to efi

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Message-ID: <CAMj1kXE4Fo3i9f3npB0MBSOZP0x7HgF4A0KX_aUSBEBmar=NpA@mail.gmail.com>
Date: Fri, 14 Nov 2025 10:26:03 +0100
From: Ard Biesheuvel <ardb@...nel.org>
To: Sumit Garg <sumit.garg@...nel.org>
Cc: linux-arm-kernel@...ts.infradead.org, linux-efi@...r.kernel.org, 
	linux-arm-msm@...r.kernel.org, catalin.marinas@....com, will@...nel.org, 
	mark.rutland@....com, andersson@...nel.org, konradybcio@...nel.org, 
	dmitry.baryshkov@....qualcomm.com, shivendra.pratap@....qualcomm.com, 
	leif.lindholm@....qualcomm.com, linux-kernel@...r.kernel.org, 
	Sumit Garg <sumit.garg@....qualcomm.com>
Subject: Re: [PATCH 2/2] arm64: efi: Pass reboot cmd parameter to efi_reboot()

On Fri, 14 Nov 2025 at 09:51, Sumit Garg <sumit.garg@...nel.org> wrote:
>
> From: Sumit Garg <sumit.garg@....qualcomm.com>
>
> EFI ResetSystem runtime service allows for platform specific reset type
> allowing the OS to pass reset data for the UEFI implementation to take
> corresponding action. So lets pass the reboot cmd parameter for the EFI
> driver to determine whether it's a platform specific reset requested or
> not.
>
> Signed-off-by: Sumit Garg <sumit.garg@....qualcomm.com>
> ---
>  arch/arm64/kernel/process.c | 2 +-
>  1 file changed, 1 insertion(+), 1 deletion(-)
>
> diff --git a/arch/arm64/kernel/process.c b/arch/arm64/kernel/process.c
> index fba7ca102a8c..51784986c568 100644
> --- a/arch/arm64/kernel/process.c
> +++ b/arch/arm64/kernel/process.c
> @@ -136,7 +136,7 @@ void machine_restart(char *cmd)
>          * ResetSystem().
>          */
>         if (efi_enabled(EFI_RUNTIME_SERVICES))
> -               efi_reboot(reboot_mode, NULL);
> +               efi_reboot(reboot_mode, cmd);
>

I agree with the general principle. However, there are already
existing callers of kernel_restart() that would end up passing a
random string to efi_reboot(), resulting in platform specific reset
with undefined result.

E.g.,

$ git grep kernel_restart\(\"
drivers/md/dm-verity-target.c:          kernel_restart("dm-verity
device corrupted");
drivers/md/dm-verity-target.c:  kernel_restart("dm-verity device has
I/O error");
drivers/memory/emif.c:                  kernel_restart("SDRAM
Over-temp Emergency restart");


>         /* Now call the architecture specific reboot code. */
>         do_kernel_restart(cmd);
> --
> 2.48.1
>