From mboxrd@z Thu Jan  1 00:00:00 1970
Return-Path: <stable-owner@vger.kernel.org>
Received: from usa-sjc-mx-foss1.foss.arm.com ([217.140.101.70]:58684 "EHLO
        foss.arm.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP
        id S2387404AbeKFUFW (ORCPT <rfc822;stable@vger.kernel.org>);
        Tue, 6 Nov 2018 15:05:22 -0500
Date: Tue, 06 Nov 2018 10:40:33 +0000
Message-ID: <86y3a6ebfi.wl-marc.zyngier@arm.com>
From: Marc Zyngier <marc.zyngier@arm.com>
To: David Long <dave.long@linaro.org>
Cc: stable@vger.kernel.org,
        Russell King - ARM Linux <linux@armlinux.org.uk>,
        Florian Fainelli <f.fainelli@gmail.com>,
        Tony Lindgren <tony@atomide.com>,
        Mark Rutland <mark.rutland@arm.com>,
        Greg KH <gregkh@linuxfoundation.org>,
        Mark Brown <broonie@kernel.org>
Subject: Re: [PATCH 4.9 09/24] ARM: spectre-v2: add firmware based hardening
In-Reply-To: <20181031135713.2873-10-dave.long@linaro.org>
References: <20181031135713.2873-1-dave.long@linaro.org>
        <20181031135713.2873-10-dave.long@linaro.org>
MIME-Version: 1.0 (generated by SEMI-EPG 1.14.7 - "Harue")
Content-Type: text/plain; charset=US-ASCII
Sender: stable-owner@vger.kernel.org
List-ID: <stable.vger.kernel.org>

On Wed, 31 Oct 2018 13:56:58 +0000,
David Long <dave.long@linaro.org> wrote:
> 
> From: Russell King <rmk+kernel@armlinux.org.uk>
> 
> Commit 10115105cb3aa17b5da1cb726ae8dd5f6854bd93 upstream.
> 
> Add firmware based hardening for cores that require more complex
> handling in firmware.
> 
> Signed-off-by: Russell King <rmk+kernel@armlinux.org.uk>
> Boot-tested-by: Tony Lindgren <tony@atomide.com>
> Reviewed-by: Tony Lindgren <tony@atomide.com>
> Reviewed-by: Marc Zyngier <marc.zyngier@arm.com>
> Signed-off-by: David A. Long <dave.long@linaro.org>
> ---
>  arch/arm/mm/proc-v7-bugs.c | 60 ++++++++++++++++++++++++++++++++++++++
>  arch/arm/mm/proc-v7.S      | 21 +++++++++++++
>  2 files changed, 81 insertions(+)
> 

[...]

> diff --git a/arch/arm/mm/proc-v7.S b/arch/arm/mm/proc-v7.S
> index 2d2e5ae85816..8fde9edb4a48 100644
> --- a/arch/arm/mm/proc-v7.S
> +++ b/arch/arm/mm/proc-v7.S
> @@ -9,6 +9,7 @@
>   *
>   *  This is the "shell" of the ARMv7 processor support.
>   */
> +#include <linux/arm-smccc.h>
>  #include <linux/init.h>
>  #include <linux/linkage.h>
>  #include <asm/assembler.h>
> @@ -88,6 +89,26 @@ ENTRY(cpu_v7_dcache_clean_area)
>  	ret	lr
>  ENDPROC(cpu_v7_dcache_clean_area)
>  
> +#ifdef CONFIG_ARM_PSCI
> +	.arch_extension sec
> +ENTRY(cpu_v7_smc_switch_mm)
> +	stmfd	sp!, {r0 - r3}
> +	movw	r0, #:lower16:ARM_SMCCC_ARCH_WORKAROUND_1
> +	movt	r0, #:upper16:ARM_SMCCC_ARCH_WORKAROUND_1
> +	smc	#0
> +	ldmfd	sp!, {r0 - r3}
> +	b	cpu_v7_switch_mm
> +ENDPROC(cpu_v7_smc_switch_mm)
> +	.arch_extension virt
> +ENTRY(cpu_v7_hvc_switch_mm)
> +	stmfd	sp!, {r0 - r3}
> +	movw	r0, #:lower16:ARM_SMCCC_ARCH_WORKAROUND_1
> +	movt	r0, #:upper16:ARM_SMCCC_ARCH_WORKAROUND_1
> +	hvc	#0
> +	ldmfd	sp!, {r0 - r3}
> +	b	cpu_v7_switch_mm
> +ENDPROC(cpu_v7_smc_switch_mm)

As pointed out by Ard a while ago [1], this breaks Thumb-2 kernels.
Please keep this series on hold until this is fixed in mainline and
you can cherry-pick the corresponding patch.

Thanks,

	M.

[1] https://patchwork.kernel.org/patch/10475033/

-- 
Jazz is not dead, it just smell funny.