linux-kernel - Re: [PATCH v3 1/8] arm64: Do not enable IRQs for ct_user

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Message-ID: <96a0eb12-bbf2-0854-a5e7-25246327e3ec@arm.com>
Date:   Fri, 7 Jun 2019 10:25:16 +0100
From:   James Morse <james.morse@....com>
To:     Julien Thierry <julien.thierry@....com>
Cc:     linux-arm-kernel@...ts.infradead.org, linux-kernel@...r.kernel.org,
        rostedt@...dmis.org, marc.zyngier@....com, yuzenghui@...wei.com,
        wanghaibin.wang@...wei.com, will.deacon@....com,
        catalin.marinas@....com, mark.rutland@....com, liwei391@...wei.com
Subject: Re: [PATCH v3 1/8] arm64: Do not enable IRQs for ct_user_exit

Hi Julien,

On 06/06/2019 10:31, Julien Thierry wrote:
> For el0_dbg and el0_error, DAIF bits get explicitly cleared before
> calling ct_user_exit.
> 
> When context tracking is disabled, DAIF gets set (almost) immediately
> after. When context tracking is enabled, among the first things done
> is disabling IRQs.
> 
> What is actually needed is:
> - PSR.D = 0 so the system can be debugged (should be already the case)
> - PSR.A = 0 so async error can be handled during context tracking
> 
> Do not clear PSR.I in those two locations.

(last time I looked at this I wrongly assumed ct_user_exit() should be run with interrupts
masked, but that isn't what you're saying).

Reviewed-by: James Morse <james.morse@....com>


Thanks,

James