linux-kernel - Re: [PATCH 2/2] arm64: export __hyp_stub

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Date:   Fri, 15 Nov 2019 10:58:32 +0100
From:   Jan Kiszka <jan.kiszka@...mens.com>
To:     Peng Fan <peng.fan@....com>,
        "catalin.marinas@....com" <catalin.marinas@....com>,
        "will@...nel.org" <will@...nel.org>
Cc:     "allison@...utok.net" <allison@...utok.net>,
        "tglx@...utronix.de" <tglx@...utronix.de>,
        "james.morse@....com" <james.morse@....com>,
        "linux-arm-kernel@...ts.infradead.org" 
        <linux-arm-kernel@...ts.infradead.org>,
        "linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
        "ralf.ramsauer@...-regensburg.de" <ralf.ramsauer@...-regensburg.de>,
        Alice Guo <alice.guo@....com>, dl-linux-imx <linux-imx@....com>
Subject: Re: [PATCH 2/2] arm64: export __hyp_stub_vectors

On 15.11.19 10:45, Peng Fan wrote:
> From: Peng Fan <peng.fan@....com>
> 
> External hypervisors, like Jailhouse, need this address when they are
> deactivated, in order to restore original state.
> 
> Signed-off-by: Peng Fan <peng.fan@....com>
> ---
>   arch/arm64/include/asm/virt.h | 2 ++
>   arch/arm64/kernel/hyp-stub.S  | 1 +
>   2 files changed, 3 insertions(+)
> 
> diff --git a/arch/arm64/include/asm/virt.h b/arch/arm64/include/asm/virt.h
> index 0958ed6191aa..b1b48353e3b3 100644
> --- a/arch/arm64/include/asm/virt.h
> +++ b/arch/arm64/include/asm/virt.h
> @@ -62,6 +62,8 @@
>    */
>   extern u32 __boot_cpu_mode[2];
>   
> +extern char __hyp_stub_vectors[];
> +
>   void __hyp_set_vectors(phys_addr_t phys_vector_base);
>   void __hyp_reset_vectors(void);
>   
> diff --git a/arch/arm64/kernel/hyp-stub.S b/arch/arm64/kernel/hyp-stub.S
> index f17af9a39562..22b728fb14bd 100644
> --- a/arch/arm64/kernel/hyp-stub.S
> +++ b/arch/arm64/kernel/hyp-stub.S
> @@ -38,6 +38,7 @@ ENTRY(__hyp_stub_vectors)
>   	ventry	el1_fiq_invalid			// FIQ 32-bit EL1
>   	ventry	el1_error_invalid		// Error 32-bit EL1
>   ENDPROC(__hyp_stub_vectors)
> +EXPORT_SYMBOL(__hyp_stub_vectors);
>   
>   	.align 11
>   
> 

While I would not dislike to have patch-free access in Jailhouse, I'm 
not sure if an out-of-tree use case justifies this an export.

Also, this lacks the arm equivalent to be complete.

Jan

-- 
Siemens AG, Corporate Technology, CT RDA IOT SES-DE
Corporate Competence Center Embedded Linux