[PATCH v2 3/9] arm64: smccc: Add support for SMCCCv1.2 input/output registers

[Andrew Walbran]

On Tue, 3 Nov 2020 at 17:44, Sudeep Holla <sudeep.holla at arm.com> 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 at 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 7d32fc959b1a..32bcc25337ce 100644
> --- a/arch/arm64/kernel/asm-offsets.c
> +++ b/arch/arm64/kernel/asm-offsets.c
> @@ -122,6 +122,10 @@ 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..aed27214c88f 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 */
> +/**
> + * struct arm_smccc_v1_2_res - Result from SMC/HVC call
> + * @a0-a3 result values from registers 0 to 3

Should this be a0-a7?

> + */
> +struct arm_smccc_v1_2_res {
> +       unsigned long a0;
> +       unsigned long a1;
> +       unsigned long a2;
> +       unsigned long a3;
> +       unsigned long a4;
> +       unsigned long a5;
> +       unsigned long a6;
> +       unsigned long a7;
> +};
> +
> +/**
> + * arm_smccc_v1_2_hvc() - make HVC calls
> + * @a0-a7: arguments passed in registers 0 to 7
> + * @res: result values from registers 0 to 7
> + *
> + * This function is used to make SMC calls following SMC Calling Convention
> + * v1.2 or above. The content of the supplied param are copied to registers
> + * 0 to 7 prior to the SMC instruction. The return values are updated with
> + * the content from register 0 to 7 on return from the SMC instruction.

s/SMC/HVC/ in several places above.

> + */
> +asmlinkage
> +void arm_smccc_v1_2_hvc(unsigned long a0, unsigned long a1, unsigned long a2,
> +                       unsigned long a3, unsigned long a4, unsigned long a5,
> +                       unsigned long a6, unsigned long a7,
> +                       struct arm_smccc_v1_2_res  *res);
> +
> +/**
> + * arm_smccc_v1_2_smc() - make SMC calls
> + * @a0-a7: arguments passed in registers 0 to 7
> + * @res: result values from registers 0 to 7
> + *
> + * This function is used to make SMC calls following SMC Calling Convention
> + * v1.2 or above. The content of the supplied param are copied to registers
> + * 0 to 7 prior to the SMC instruction. The return values are updated with
> + * the content from register 0 to 7 on return from the SMC instruction.
> + */
> +asmlinkage
> +void arm_smccc_v1_2_smc(unsigned long a0, unsigned long a1, unsigned long a2,
> +                       unsigned long a3, unsigned long a4, unsigned long a5,
> +                       unsigned long a6, unsigned long a7,
> +                       struct arm_smccc_v1_2_res  *res);
> +#endif
> +
>  /**
>   * struct arm_smccc_quirk - Contains quirk information
>   * @id: quirk identification
> --
> 2.25.1
>
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