Re: [PATCH v12 01/10] arm64: smccc: add support for SMCCCv1.2 x0-x17 registers

Ilias Apalodimas
2023-05-19T12:56:49Z

On Fri, May 12, 2023 at 01:10:35PM +0100, Abdellatif El Khlifi wrote:
> add support for x0-x17 registers used by the SMC calls
>
> In SMCCC v1.2 [1] arguments are passed in registers x1-x17.
> Results are returned in x0-x17.
>
> This work is inspired from the following kernel commit:
>
> arm64: smccc: Add support for SMCCCv1.2 extended input/output registers
>
> [1]: https://documentation-service.arm.com/static/5f8edaeff86e16515cdbe4c6?token=
>
> Signed-off-by: Abdellatif El Khlifi <abdellatif.elkhlifi@arm.com>
> Reviewed-by: Jens Wiklander <jens.wiklander@linaro.org>
> Reviewed-by: Simon Glass <sjg@chromium.org>
> Cc: Tom Rini <trini@konsulko.com>
> Cc: Simon Glass <sjg@chromium.org>
> Cc: Ilias Apalodimas <ilias.apalodimas@linaro.org>
>
> ---
>
> Changelog:
> ===============
>
> v9:
>
> * update the copyright string
>
> v7:
>
> * improve indentation of ARM_SMCCC_1_2_REGS_Xn_OFFS
>
> v4:
>
> * rename the commit title and improve description
> new commit title: the current
>
> v3:
>
> * port x0-x17 registers support from linux kernel as defined by SMCCCv1.2
> commit title:
> arm64: smccc: add Xn registers support used by SMC calls
>
> arch/arm/cpu/armv8/smccc-call.S | 57 ++++++++++++++++++++++++++++++++-
> arch/arm/lib/asm-offsets.c | 16 +++++++++
> include/linux/arm-smccc.h | 45 ++++++++++++++++++++++++++
> 3 files changed, 117 insertions(+), 1 deletion(-)
>
> diff --git a/arch/arm/cpu/armv8/smccc-call.S b/arch/arm/cpu/armv8/smccc-call.S
> index dc92b28777..93f66d3366 100644
> --- a/arch/arm/cpu/armv8/smccc-call.S
> +++ b/arch/arm/cpu/armv8/smccc-call.S
> @@ -1,7 +1,11 @@
> /* SPDX-License-Identifier: GPL-2.0 */
> /*
> * Copyright (c) 2015, Linaro Limited
> - */
> + * Copyright 2022-2023 Arm Limited and/or its affiliates <open-source-office@arm.com>
> + *
> + * Authors:
> + * Abdellatif El Khlifi <abdellatif.elkhlifi@arm.com>
> +*/
> #include <linux/linkage.h>
> #include <linux/arm-smccc.h>
> #include <generated/asm-offsets.h>
> @@ -45,3 +49,54 @@ ENDPROC(__arm_smccc_smc)
> ENTRY(__arm_smccc_hvc)
> SMCCC hvc
> ENDPROC(__arm_smccc_hvc)
> +
> +#ifdef CONFIG_ARM64
> +
> + .macro SMCCC_1_2 instr
> + /* Save `res` and free a GPR that won't be clobbered */
> + stp x1, x19, [sp, #-16]!
> +
> + /* Ensure `args` won't be clobbered while loading regs in next step */
> + mov x19, x0
> +
> + /* Load the registers x0 - x17 from the struct arm_smccc_1_2_regs */
> + ldp x0, x1, [x19, #ARM_SMCCC_1_2_REGS_X0_OFFS]
> + ldp x2, x3, [x19, #ARM_SMCCC_1_2_REGS_X2_OFFS]
> + ldp x4, x5, [x19, #ARM_SMCCC_1_2_REGS_X4_OFFS]
> + ldp x6, x7, [x19, #ARM_SMCCC_1_2_REGS_X6_OFFS]
> + ldp x8, x9, [x19, #ARM_SMCCC_1_2_REGS_X8_OFFS]
> + ldp x10, x11, [x19, #ARM_SMCCC_1_2_REGS_X10_OFFS]
> + ldp x12, x13, [x19, #ARM_SMCCC_1_2_REGS_X12_OFFS]
> + ldp x14, x15, [x19, #ARM_SMCCC_1_2_REGS_X14_OFFS]
> + ldp x16, x17, [x19, #ARM_SMCCC_1_2_REGS_X16_OFFS]
> +
> + \instr #0
> +
> + /* Load the `res` from the stack */
> + ldr x19, [sp]
> +
> + /* Store the registers x0 - x17 into the result structure */
> + stp x0, x1, [x19, #ARM_SMCCC_1_2_REGS_X0_OFFS]
> + stp x2, x3, [x19, #ARM_SMCCC_1_2_REGS_X2_OFFS]
> + stp x4, x5, [x19, #ARM_SMCCC_1_2_REGS_X4_OFFS]
> + stp x6, x7, [x19, #ARM_SMCCC_1_2_REGS_X6_OFFS]
> + stp x8, x9, [x19, #ARM_SMCCC_1_2_REGS_X8_OFFS]
> + stp x10, x11, [x19, #ARM_SMCCC_1_2_REGS_X10_OFFS]
> + stp x12, x13, [x19, #ARM_SMCCC_1_2_REGS_X12_OFFS]
> + stp x14, x15, [x19, #ARM_SMCCC_1_2_REGS_X14_OFFS]
> + stp x16, x17, [x19, #ARM_SMCCC_1_2_REGS_X16_OFFS]
> +
> + /* Restore original x19 */
> + ldp xzr, x19, [sp], #16
> + ret
> + .endm
> +
> +/*
> + * void arm_smccc_1_2_smc(const struct arm_smccc_1_2_regs *args,
> + * struct arm_smccc_1_2_regs *res);
> + */
> +ENTRY(arm_smccc_1_2_smc)
> + SMCCC_1_2 smc
> +ENDPROC(arm_smccc_1_2_smc)
> +
> +#endif
> diff --git a/arch/arm/lib/asm-offsets.c b/arch/arm/lib/asm-offsets.c
> index 6de0ce9152..181a8ac4c2 100644
> --- a/arch/arm/lib/asm-offsets.c
> +++ b/arch/arm/lib/asm-offsets.c
> @@ -9,6 +9,11 @@
> * generate asm statements containing #defines,
> * compile this file to assembler, and then extract the
> * #defines from the assembly-language output.
> + *
> + * Copyright 2022-2023 Arm Limited and/or its affiliates <open-source-office@arm.com>
> + *
> + * Authors:
> + * Abdellatif El Khlifi <abdellatif.elkhlifi@arm.com>
> */
>
> #include <common.h>
> @@ -90,6 +95,17 @@ 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));
> +#ifdef CONFIG_ARM64
> + DEFINE(ARM_SMCCC_1_2_REGS_X0_OFFS, offsetof(struct arm_smccc_1_2_regs, a0));
> + DEFINE(ARM_SMCCC_1_2_REGS_X2_OFFS, offsetof(struct arm_smccc_1_2_regs, a2));
> + DEFINE(ARM_SMCCC_1_2_REGS_X4_OFFS, offsetof(struct arm_smccc_1_2_regs, a4));
> + DEFINE(ARM_SMCCC_1_2_REGS_X6_OFFS, offsetof(struct arm_smccc_1_2_regs, a6));
> + DEFINE(ARM_SMCCC_1_2_REGS_X8_OFFS, offsetof(struct arm_smccc_1_2_regs, a8));
> + DEFINE(ARM_SMCCC_1_2_REGS_X10_OFFS, offsetof(struct arm_smccc_1_2_regs, a10));
> + DEFINE(ARM_SMCCC_1_2_REGS_X12_OFFS, offsetof(struct arm_smccc_1_2_regs, a12));
> + DEFINE(ARM_SMCCC_1_2_REGS_X14_OFFS, offsetof(struct arm_smccc_1_2_regs, a14));
> + DEFINE(ARM_SMCCC_1_2_REGS_X16_OFFS, offsetof(struct arm_smccc_1_2_regs, a16));
> +#endif
> #endif
>
> return 0;
> diff --git a/include/linux/arm-smccc.h b/include/linux/arm-smccc.h
> index e1d09884a1..f44e9e8f93 100644
> --- a/include/linux/arm-smccc.h
> +++ b/include/linux/arm-smccc.h
> @@ -1,6 +1,10 @@
> /* SPDX-License-Identifier: GPL-2.0 */
> /*
> * Copyright (c) 2015, Linaro Limited
> + * Copyright 2022-2023 Arm Limited and/or its affiliates <open-source-office@arm.com>
> + *
> + * Authors:
> + * Abdellatif El Khlifi <abdellatif.elkhlifi@arm.com>
> */
> #ifndef __LINUX_ARM_SMCCC_H
> #define __LINUX_ARM_SMCCC_H
> @@ -70,6 +74,47 @@ struct arm_smccc_res {
> unsigned long a3;
> };
>
> +#ifdef CONFIG_ARM64
> +/**
> + * struct arm_smccc_1_2_regs - Arguments for or Results from SMC call
> + * @a0-a17 argument values from registers 0 to 17
> + */
> +struct arm_smccc_1_2_regs {
> + unsigned long a0;
> + unsigned long a1;
> + unsigned long a2;
> + unsigned long a3;
> + unsigned long a4;
> + unsigned long a5;
> + unsigned long a6;
> + unsigned long a7;
> + unsigned long a8;
> + unsigned long a9;
> + unsigned long a10;
> + unsigned long a11;
> + unsigned long a12;
> + unsigned long a13;
> + unsigned long a14;
> + unsigned long a15;
> + unsigned long a16;
> + unsigned long a17;
> +};
> +
> +/**
> + * arm_smccc_1_2_smc() - make SMC calls
> + * @args: arguments passed via struct arm_smccc_1_2_regs
> + * @res: result values via struct arm_smccc_1_2_regs
> + *
> + * This function is used to make SMC calls following SMC Calling Convention
> + * v1.2 or above. The content of the supplied param are copied from the
> + * structure to registers prior to the SMC instruction. The return values
> + * are updated with the content from registers on return from the SMC
> + * instruction.
> + */
> +asmlinkage void arm_smccc_1_2_smc(const struct arm_smccc_1_2_regs *args,
> + struct arm_smccc_1_2_regs *res);
> +#endif
> +
> /**
> * struct arm_smccc_quirk - Contains quirk information
> * @id: quirk identification
> --
> 2.25.1
>

Reviewed-by: Ilias Apalodimas <ilias.apalodimas@linaro.org>