From mboxrd@z Thu Jan  1 00:00:00 1970
From: marc.zyngier@arm.com (Marc Zyngier)
Date: Tue, 19 Apr 2016 16:10:16 +0100
Subject: [PATCH v7 04/16] arm64: kvm: Move the do_el2_call macro to a
 header file
In-Reply-To: <5716491E.4050607@arm.com>
References: <1459529620-22150-1-git-send-email-james.morse@arm.com>
 <1459529620-22150-5-git-send-email-james.morse@arm.com>
 <57164897.8090603@arm.com> <5716491E.4050607@arm.com>
Message-ID: <57164A58.3020603@arm.com>
To: linux-arm-kernel@lists.infradead.org
List-Id: linux-arm-kernel.lists.infradead.org

On 19/04/16 16:05, James Morse wrote:
> Hi Marc,
> 
> On 19/04/16 16:02, Marc Zyngier wrote:
>> On 01/04/16 17:53, James Morse wrote:
>>> 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.
> 
> Ah, I hadn't thought of it like that!
> 
> 
>> Could we have a disclaimer saying something along the lines of "Don't
>> you dare using this macro!"?
> 
> Or rename it? Something like 'unpack_el2_call'.

Works for me!

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