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From: Marc Zyngier <maz@kernel.org>
To: Andrew Scull <ascull@google.com>
Cc: kernel-team@android.com, catalin.marinas@arm.com,
	linux-arm-kernel@lists.infradead.org,
	Sudeep Holla <sudeep.holla@arm.com>,
	will@kernel.org, kvmarm@lists.cs.columbia.edu
Subject: Re: [PATCH v3 14/18] smccc: Cast arguments to unsigned long
Date: Mon, 07 Sep 2020 14:33:17 +0100	[thread overview]
Message-ID: <87r1rdlnj6.wl-maz@kernel.org> (raw)
In-Reply-To: <20200903135307.251331-15-ascull@google.com>

On Thu, 03 Sep 2020 14:53:03 +0100,
Andrew Scull <ascull@google.com> wrote:
> 
> To avoid warning about implicit casting, make the casting explicit. This
> allows, for example, pointers to be used as arguments as are used in the
> KVM hyp interface.
> 
> Cc: Sudeep Holla <sudeep.holla@arm.com>
> Signed-off-by: Andrew Scull <ascull@google.com>
> ---
>  include/linux/arm-smccc.h | 20 ++++++++++----------
>  1 file changed, 10 insertions(+), 10 deletions(-)
> 
> diff --git a/include/linux/arm-smccc.h b/include/linux/arm-smccc.h
> index 15c706fb0a37..3bb109a35554 100644
> --- a/include/linux/arm-smccc.h
> +++ b/include/linux/arm-smccc.h
> @@ -260,7 +260,7 @@ asmlinkage void __arm_smccc_hvc(unsigned long a0, unsigned long a1,
>  	typeof(a1) __a1 = a1;						\
>  	struct arm_smccc_res   *___res = res;				\
>  	register unsigned long r0 asm("r0") = (u32)a0;			\
> -	register unsigned long r1 asm("r1") = __a1;			\
> +	register unsigned long r1 asm("r1") = (unsigned long)__a1;	\

Given the pain we go through to extract the type of each argument, it
seems odd to end-up with casts everywhere. I'd rather keep the type
system alive by having:

	register typeof(a1) r1 asm("r1") = __a1;

Is there any reason why this doesn't work?

Thanks,

	M.

-- 
Without deviation from the norm, progress is not possible.
_______________________________________________
kvmarm mailing list
kvmarm@lists.cs.columbia.edu
https://lists.cs.columbia.edu/mailman/listinfo/kvmarm

WARNING: multiple messages have this Message-ID (diff)
From: Marc Zyngier <maz@kernel.org>
To: Andrew Scull <ascull@google.com>
Cc: kernel-team@android.com, suzuki.poulose@arm.com,
	catalin.marinas@arm.com, james.morse@arm.com,
	linux-arm-kernel@lists.infradead.org,
	Sudeep Holla <sudeep.holla@arm.com>,
	will@kernel.org, kvmarm@lists.cs.columbia.edu,
	julien.thierry.kdev@gmail.com
Subject: Re: [PATCH v3 14/18] smccc: Cast arguments to unsigned long
Date: Mon, 07 Sep 2020 14:33:17 +0100	[thread overview]
Message-ID: <87r1rdlnj6.wl-maz@kernel.org> (raw)
In-Reply-To: <20200903135307.251331-15-ascull@google.com>

On Thu, 03 Sep 2020 14:53:03 +0100,
Andrew Scull <ascull@google.com> wrote:
> 
> To avoid warning about implicit casting, make the casting explicit. This
> allows, for example, pointers to be used as arguments as are used in the
> KVM hyp interface.
> 
> Cc: Sudeep Holla <sudeep.holla@arm.com>
> Signed-off-by: Andrew Scull <ascull@google.com>
> ---
>  include/linux/arm-smccc.h | 20 ++++++++++----------
>  1 file changed, 10 insertions(+), 10 deletions(-)
> 
> diff --git a/include/linux/arm-smccc.h b/include/linux/arm-smccc.h
> index 15c706fb0a37..3bb109a35554 100644
> --- a/include/linux/arm-smccc.h
> +++ b/include/linux/arm-smccc.h
> @@ -260,7 +260,7 @@ asmlinkage void __arm_smccc_hvc(unsigned long a0, unsigned long a1,
>  	typeof(a1) __a1 = a1;						\
>  	struct arm_smccc_res   *___res = res;				\
>  	register unsigned long r0 asm("r0") = (u32)a0;			\
> -	register unsigned long r1 asm("r1") = __a1;			\
> +	register unsigned long r1 asm("r1") = (unsigned long)__a1;	\

Given the pain we go through to extract the type of each argument, it
seems odd to end-up with casts everywhere. I'd rather keep the type
system alive by having:

	register typeof(a1) r1 asm("r1") = __a1;

Is there any reason why this doesn't work?

Thanks,

	M.

-- 
Without deviation from the norm, progress is not possible.

_______________________________________________
linux-arm-kernel mailing list
linux-arm-kernel@lists.infradead.org
http://lists.infradead.org/mailman/listinfo/linux-arm-kernel

  reply	other threads:[~2020-09-07 13:33 UTC|newest]

Thread overview: 72+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2020-09-03 13:52 [PATCH v3 00/18] Introduce separate nVHE hyp context Andrew Scull
2020-09-03 13:52 ` Andrew Scull
2020-09-03 13:52 ` [PATCH v3 01/18] KVM: arm64: Remove __activate_vm wrapper Andrew Scull
2020-09-03 13:52   ` Andrew Scull
2020-09-03 13:52 ` [PATCH v3 02/18] KVM: arm64: Remove hyp_panic arguments Andrew Scull
2020-09-03 13:52   ` Andrew Scull
2020-09-07 10:21   ` Marc Zyngier
2020-09-07 10:21     ` Marc Zyngier
2020-09-03 13:52 ` [PATCH v3 03/18] KVM: arm64: Remove kvm_host_data_t typedef Andrew Scull
2020-09-03 13:52   ` Andrew Scull
2020-09-03 13:52 ` [PATCH v3 04/18] KVM: arm64: Restrict symbol aliasing to outside nVHE Andrew Scull
2020-09-03 13:52   ` Andrew Scull
2020-09-07 10:38   ` Marc Zyngier
2020-09-07 10:38     ` Marc Zyngier
2020-09-08 10:13     ` Andrew Scull
2020-09-08 10:13       ` Andrew Scull
2020-09-03 13:52 ` [PATCH v3 05/18] KVM: arm64: Save chosen hyp vector to a percpu variable Andrew Scull
2020-09-03 13:52   ` Andrew Scull
2020-09-03 13:52 ` [PATCH v3 06/18] KVM: arm64: nVHE: Use separate vector for the host Andrew Scull
2020-09-03 13:52   ` Andrew Scull
2020-09-07 11:38   ` Marc Zyngier
2020-09-07 11:38     ` Marc Zyngier
2020-09-08 10:29     ` Andrew Scull
2020-09-08 10:29       ` Andrew Scull
2020-09-03 13:52 ` [PATCH v3 07/18] KVM: arm64: nVHE: Don't consume host SErrors with ESB Andrew Scull
2020-09-03 13:52   ` Andrew Scull
2020-09-07 11:46   ` Marc Zyngier
2020-09-07 11:46     ` Marc Zyngier
2020-09-03 13:52 ` [PATCH v3 08/18] KVM: arm64: Introduce hyp context Andrew Scull
2020-09-03 13:52   ` Andrew Scull
2020-09-07 13:29   ` Marc Zyngier
2020-09-07 13:29     ` Marc Zyngier
2020-09-08 10:52     ` Andrew Scull
2020-09-08 10:52       ` Andrew Scull
2020-09-03 13:52 ` [PATCH v3 09/18] KVM: arm64: Update context references from host to hyp Andrew Scull
2020-09-03 13:52   ` Andrew Scull
2020-09-03 13:52 ` [PATCH v3 10/18] KVM: arm64: Restore hyp when panicking in guest context Andrew Scull
2020-09-03 13:52   ` Andrew Scull
2020-09-03 13:53 ` [PATCH v3 11/18] KVM: arm64: Share context save and restore macros Andrew Scull
2020-09-03 13:53   ` Andrew Scull
2020-09-03 13:53 ` [PATCH v3 12/18] KVM: arm64: nVHE: Switch to hyp context for EL2 Andrew Scull
2020-09-03 13:53   ` Andrew Scull
2020-09-07 13:02   ` Marc Zyngier
2020-09-07 13:02     ` Marc Zyngier
2020-09-08 10:42     ` Andrew Scull
2020-09-08 10:42       ` Andrew Scull
2020-09-03 13:53 ` [PATCH v3 13/18] KVM: arm64: nVHE: Handle hyp panics Andrew Scull
2020-09-03 13:53   ` Andrew Scull
2020-09-07 13:24   ` Marc Zyngier
2020-09-07 13:24     ` Marc Zyngier
2020-09-03 13:53 ` [PATCH v3 14/18] smccc: Cast arguments to unsigned long Andrew Scull
2020-09-03 13:53   ` Andrew Scull
2020-09-07 13:33   ` Marc Zyngier [this message]
2020-09-07 13:33     ` Marc Zyngier
2020-09-08 10:58     ` Andrew Scull
2020-09-08 10:58       ` Andrew Scull
2020-09-03 13:53 ` [PATCH v3 15/18] KVM: arm64: nVHE: Pass pointers consistently to hyp-init Andrew Scull
2020-09-03 13:53   ` Andrew Scull
2020-09-03 13:53 ` [PATCH v3 16/18] KVM: arm64: nVHE: Migrate hyp interface to SMCCC Andrew Scull
2020-09-03 13:53   ` Andrew Scull
2020-09-07 13:47   ` Marc Zyngier
2020-09-07 13:47     ` Marc Zyngier
2020-09-07 14:20   ` Marc Zyngier
2020-09-07 14:20     ` Marc Zyngier
2020-09-08 11:02     ` Andrew Scull
2020-09-08 11:02       ` Andrew Scull
2020-09-09  8:30       ` Andrew Scull
2020-09-09  8:30         ` Andrew Scull
2020-09-03 13:53 ` [PATCH v3 17/18] KVM: arm64: nVHE: Migrate hyp-init " Andrew Scull
2020-09-03 13:53   ` Andrew Scull
2020-09-03 13:53 ` [PATCH v3 18/18] KVM: arm64: nVHE: Fix pointers during SMCCC convertion Andrew Scull
2020-09-03 13:53   ` Andrew Scull

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