Re: [PATCH v4 2/7] arm64: smccc: Add support for SMCCCv1.2 input/output registers

[Jens Wiklander <jens.wiklander@linaro.org>]

On Fri, Feb 12, 2021 at 03:46:09PM +0000, Sudeep Holla wrote:
> SMCCC v1.2 allows x8-x17 to be used as parameter registers and x4—x17
> to be used as result registers in SMC64/HVC64. Arm Firmware Framework
> for Armv8-A specification makes use of x0-x7 as parameter and result
> registers.
> 
> Current SMCCC interface in the kernel just use x0-x7 as parameter and
> x0-x3 as result registers. Let us add new interface to support x0-x7
> as parameter and result registers. This can be extended to include
> x8-x17 when there are users for the same.
> 
> Signed-off-by: Sudeep Holla <sudeep.holla@arm.com>
> ---
>  arch/arm64/kernel/asm-offsets.c |  4 +++
>  arch/arm64/kernel/smccc-call.S  | 22 +++++++++++++++
>  include/linux/arm-smccc.h       | 50 +++++++++++++++++++++++++++++++++
>  3 files changed, 76 insertions(+)
> 
> diff --git a/arch/arm64/kernel/asm-offsets.c b/arch/arm64/kernel/asm-offsets.c
> index 301784463587..89b444591575 100644
> --- a/arch/arm64/kernel/asm-offsets.c
> +++ b/arch/arm64/kernel/asm-offsets.c
> @@ -129,6 +129,10 @@ int main(void)
>    DEFINE(ARM_SMCCC_RES_X2_OFFS,		offsetof(struct arm_smccc_res, a2));
>    DEFINE(ARM_SMCCC_QUIRK_ID_OFFS,	offsetof(struct arm_smccc_quirk, id));
>    DEFINE(ARM_SMCCC_QUIRK_STATE_OFFS,	offsetof(struct arm_smccc_quirk, state));
> +  DEFINE(ARM_SMCCC_V1_2_RES_X0_OFFS,	offsetof(struct arm_smccc_v1_2_res, a0));
> +  DEFINE(ARM_SMCCC_V1_2_RES_X2_OFFS,	offsetof(struct arm_smccc_v1_2_res, a2));
> +  DEFINE(ARM_SMCCC_V1_2_RES_X4_OFFS,	offsetof(struct arm_smccc_v1_2_res, a4));
> +  DEFINE(ARM_SMCCC_V1_2_RES_X6_OFFS,	offsetof(struct arm_smccc_v1_2_res, a6));
>    BLANK();
>    DEFINE(HIBERN_PBE_ORIG,	offsetof(struct pbe, orig_address));
>    DEFINE(HIBERN_PBE_ADDR,	offsetof(struct pbe, address));
> diff --git a/arch/arm64/kernel/smccc-call.S b/arch/arm64/kernel/smccc-call.S
> index d62447964ed9..0ea15c1742f3 100644
> --- a/arch/arm64/kernel/smccc-call.S
> +++ b/arch/arm64/kernel/smccc-call.S
> @@ -43,3 +43,25 @@ SYM_FUNC_START(__arm_smccc_hvc)
>  	SMCCC	hvc
>  SYM_FUNC_END(__arm_smccc_hvc)
>  EXPORT_SYMBOL(__arm_smccc_hvc)
> +
> +	.macro SMCCC_v1_2 instr
> +	.cfi_startproc
> +	\instr #0
> +	ldr x8, [sp]
> +	stp x0, x1, [x8, #ARM_SMCCC_V1_2_RES_X0_OFFS]
> +	stp x2, x3, [x8, #ARM_SMCCC_V1_2_RES_X2_OFFS]
> +	stp x4, x5, [x8, #ARM_SMCCC_V1_2_RES_X4_OFFS]
> +	stp x6, x7, [x8, #ARM_SMCCC_V1_2_RES_X6_OFFS]
> +	ret
> +	.cfi_endproc
> +.endm
> +
> +SYM_FUNC_START(arm_smccc_v1_2_hvc)
> +	SMCCC_v1_2 hvc
> +SYM_FUNC_END(arm_smccc_v1_2_hvc)
> +EXPORT_SYMBOL(arm_smccc_v1_2_hvc)
> +
> +SYM_FUNC_START(arm_smccc_v1_2_smc)
> +	SMCCC_v1_2 smc
> +SYM_FUNC_END(arm_smccc_v1_2_smc)
> +EXPORT_SYMBOL(arm_smccc_v1_2_smc)
> diff --git a/include/linux/arm-smccc.h b/include/linux/arm-smccc.h
> index f860645f6512..66fd3d582c7f 100644
> --- a/include/linux/arm-smccc.h
> +++ b/include/linux/arm-smccc.h
> @@ -155,6 +155,56 @@ struct arm_smccc_res {
>  	unsigned long a3;
>  };
>  
> +#ifdef CONFIG_ARM64
> +/* TODO Need to implement for ARM too */

It would be nice to have this TODO resolved.

Thanks,
Jens