From mboxrd@z Thu Jan  1 00:00:00 1970
From: marc.zyngier@arm.com (Marc Zyngier)
Date: Tue, 19 Apr 2016 16:02:47 +0100
Subject: [PATCH v7 04/16] arm64: kvm: Move the do_el2_call macro to a
 header file
In-Reply-To: <1459529620-22150-5-git-send-email-james.morse@arm.com>
References: <1459529620-22150-1-git-send-email-james.morse@arm.com>
 <1459529620-22150-5-git-send-email-james.morse@arm.com>
Message-ID: <57164897.8090603@arm.com>
To: linux-arm-kernel@lists.infradead.org
List-Id: linux-arm-kernel.lists.infradead.org

On 01/04/16 17:53, James Morse wrote:
> The hyp-stub could make use of the do_el2_call(), move it to a header file.
> 
> Signed-off-by: James Morse <james.morse@arm.com>
> ---
>  arch/arm64/include/asm/virt.h  | 18 +++++++++++++++++-
>  arch/arm64/kvm/hyp/hyp-entry.S | 17 +----------------
>  2 files changed, 18 insertions(+), 17 deletions(-)
> 
> diff --git a/arch/arm64/include/asm/virt.h b/arch/arm64/include/asm/virt.h
> index 9f22dd607958..b8fdddeca71b 100644
> --- a/arch/arm64/include/asm/virt.h
> +++ b/arch/arm64/include/asm/virt.h
> @@ -21,7 +21,23 @@
>  #define BOOT_CPU_MODE_EL1	(0xe11)
>  #define BOOT_CPU_MODE_EL2	(0xe12)
>  
> -#ifndef __ASSEMBLY__
> +#ifdef __ASSEMBLY__
> +.macro do_el2_call
> +	/*
> +	 * Shuffle the parameters before calling the function
> +	 * pointed to in x0. Assumes parameters in x[1,2,3].
> +	 */
> +	sub	sp, sp, #16
> +	str	lr, [sp]
> +	mov	lr, x0
> +	mov	x0, x1
> +	mov	x1, x2
> +	mov	x2, x3
> +	blr	lr
> +	ldr	lr, [sp]
> +	add	sp, sp, #16
> +.endm
> +#else

So while I'm not opposed to this macro being reused, the name is
slightly misleading out of the original context. This macro doesn't take
you to EL2, but implements a very peculiar calling convention that only
the HYP code is expecting.

Could we have a disclaimer saying something along the lines of "Don't
you dare using this macro!"?

Otherwise:

Acked-by: Marc Zyngier <marc.zyngier@arm.com>

	M.
-- 
Jazz is not dead. It just smells funny...