Re: [Xen-devel] [RFC PATCH 16/31] arm: add SMC wrapper that is compatible with SMCCC

[Stefano Stabellini <sstabellini@xxxxxxxxxx>]

On Thu, 9 Nov 2017, Oleksandr Tyshchenko wrote:
> From: Volodymyr Babchuk <volodymyr_babchuk@xxxxxxxx>
> 
> Existing SMC wrapper call_smc() allows only 4 parameters and
> returns only one value. This is enough for existing
> use in PSCI code, but TEE mediator will need a call that is
> fully compatible with ARM SMCCC.
> This patch adds this call for both arm32 and arm64.
> 
> There was similar patch by Edgar E. Iglesias ([1]), but looks
> like it is abandoned.
> 
> [1] https://lists.xenproject.org/archives/html/xen-devel/2017-02/msg00636.html
> 
> CC: "Edgar E. Iglesias" <edgar.iglesias@xxxxxxxxxx>
> 
> Signed-off-by: Volodymyr Babchuk <volodymyr_babchuk@xxxxxxxx>
> CC: Stefano Stabellini <sstabellini@xxxxxxxxxx>
> CC: Julien Grall <julien.grall@xxxxxxxxxx>
> ---
>  xen/arch/arm/arm32/Makefile     |  1 +
>  xen/arch/arm/arm32/smc.S        | 32 ++++++++++++++++++++++++++++++++
>  xen/arch/arm/arm64/Makefile     |  1 +
>  xen/arch/arm/arm64/smc.S        | 29 +++++++++++++++++++++++++++++
>  xen/include/asm-arm/processor.h |  4 ++++
>  5 files changed, 67 insertions(+)
>  create mode 100644 xen/arch/arm/arm32/smc.S
>  create mode 100644 xen/arch/arm/arm64/smc.S
> 
> diff --git a/xen/arch/arm/arm32/Makefile b/xen/arch/arm/arm32/Makefile
> index 0ac254f..a2362f3 100644
> --- a/xen/arch/arm/arm32/Makefile
> +++ b/xen/arch/arm/arm32/Makefile
> @@ -8,6 +8,7 @@ obj-y += insn.o
>  obj-$(CONFIG_LIVEPATCH) += livepatch.o
>  obj-y += proc-v7.o proc-caxx.o
>  obj-y += smpboot.o
> +obj-y += smc.o
>  obj-y += traps.o
>  obj-y += vfp.o
>  
> diff --git a/xen/arch/arm/arm32/smc.S b/xen/arch/arm/arm32/smc.S
> new file mode 100644
> index 0000000..1cc9528
> --- /dev/null
> +++ b/xen/arch/arm/arm32/smc.S
> @@ -0,0 +1,32 @@
> +/*
> + * xen/arch/arm/arm32/smc.S
> + *
> + * Wrapper for Secure Monitors Calls
> + *
> + * This program is free software; you can redistribute it and/or modify
> + * it under the terms of the GNU General Public License as published by
> + * the Free Software Foundation; either version 2 of the License, or
> + * (at your option) any later version.
> + *
> + * This program is distributed in the hope that it will be useful,
> + * but WITHOUT ANY WARRANTY; without even the implied warranty of
> + * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
> + * GNU General Public License for more details.
> + */
> +
> +#include <asm/macros.h>
> +
> +/*
> + * void call_smccc_smc(register_t a0, register_t a1, register_t a2,
> + *                     register_t a3, register_t a4, register_t a5,
> + *                     register_t a6, register_t a7, register_t res[4])
> + */
> +ENTRY(call_smccc_smc)
> +        mov     r12, sp
> +        push    {r4-r7}
> +        ldm     r12, {r4-r7}
> +        smc     #0
> +        pop     {r4-r7}
> +        ldr     r12, [sp, #(4 * 4)]

I haven't run this, but shouldn't it be:

  ldr     r12, [sp, #20]

?


> +        stm     r12, {r0-r3}
> +        bx      lr
> diff --git a/xen/arch/arm/arm64/Makefile b/xen/arch/arm/arm64/Makefile
> index 149b6b3..7831dc1 100644
> --- a/xen/arch/arm/arm64/Makefile
> +++ b/xen/arch/arm/arm64/Makefile
> @@ -8,5 +8,6 @@ obj-y += entry.o
>  obj-y += insn.o
>  obj-$(CONFIG_LIVEPATCH) += livepatch.o
>  obj-y += smpboot.o
> +obj-y += smc.o
>  obj-y += traps.o
>  obj-y += vfp.o
> diff --git a/xen/arch/arm/arm64/smc.S b/xen/arch/arm/arm64/smc.S
> new file mode 100644
> index 0000000..aa44fba
> --- /dev/null
> +++ b/xen/arch/arm/arm64/smc.S
> @@ -0,0 +1,29 @@
> +/*
> + * xen/arch/arm/arm64/smc.S
> + *
> + * Wrapper for Secure Monitors Calls
> + *
> + * This program is free software; you can redistribute it and/or modify
> + * it under the terms of the GNU General Public License as published by
> + * the Free Software Foundation; either version 2 of the License, or
> + * (at your option) any later version.
> + *
> + * This program is distributed in the hope that it will be useful,
> + * but WITHOUT ANY WARRANTY; without even the implied warranty of
> + * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
> + * GNU General Public License for more details.
> + */
> +
> +#include <asm/macros.h>
> +
> +/*
> + * void call_smccc_smc(register_t a0, register_t a1, register_t a2,
> + *                     register_t a3, register_t a4, register_t a5,
> + *                     register_t a6, register_t a7, register_t res[4])
> + */
> +ENTRY(call_smccc_smc)
> +        smc     #0
> +        ldr     x4, [sp]
> +        stp     x0, x1, [x4, 0]
> +        stp     x2, x3, [x4, 16]
> +        ret
> diff --git a/xen/include/asm-arm/processor.h b/xen/include/asm-arm/processor.h
> index 9f7a42f..4ce5bb6 100644
> --- a/xen/include/asm-arm/processor.h
> +++ b/xen/include/asm-arm/processor.h
> @@ -786,6 +786,10 @@ void vcpu_regs_user_to_hyp(struct vcpu *vcpu,
>  int call_smc(register_t function_id, register_t arg0, register_t arg1,
>               register_t arg2);
>  
> +void call_smccc_smc(register_t a0, register_t a1, register_t a2,
> +                    register_t a3, register_t a4, register_t a5,
> +                    register_t a6, register_t a7, register_t res[4]);
> +
>  void do_trap_hyp_serror(struct cpu_user_regs *regs);
>  
>  void do_trap_guest_serror(struct cpu_user_regs *regs);
> -- 
> 2.7.4
> 

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