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From: Joey Gouly <joey.gouly@arm.com>
To: Mark Rutland <mark.rutland@arm.com>
Cc: linux-arm-kernel@lists.infradead.org, catalin.marinas@arm.com,
	james.morse@arm.com, maz@kernel.org, will@kernel.org, nd@arm.com
Subject: Re: [PATCH v2 02/19] arm64: entry: unmask IRQ+FIQ after EL0 handling
Date: Tue, 25 May 2021 17:45:24 +0100	[thread overview]
Message-ID: <20210525164524.GP35816@e124191.cambridge.arm.com> (raw)
In-Reply-To: <20210519123902.2452-3-mark.rutland@arm.com>

On Wed, May 19, 2021 at 01:38:45PM +0100, Mark Rutland wrote:
> For non-fatal exceptions taken from EL0, we expect that at some point
> during exception handling it is possible to return to a regular process
> context with all exceptions unmasked (e.g. as we do in
> do_notify_resume()), and we generally aim to unmask exceptions wherever
> possible.
> 
> While handling SError and debug exceptions from EL0, we need to leave
> some exceptions masked during handling. Handling SError requires us to
> mask SError (which also requires masking IRQ+FIQ), and handing debug
> exceptions requires us to mask debug (which also requires masking
> SError+IRQ+FIQ).
> 
> Once do_serror() or do_debug_exception() has returned, we no longer need
> to mask exceptions, and can unmask them all, which is what we did prior
> to commit:
> 
>   9034f6251572a474 ("arm64: Do not enable IRQs for ct_user_exit")
> 
> ... where we had to mask IRQs as for context_tracking_user_exit()
> expected IRQs to be masked.
> 
> Since then, we realised that our context tracking wasn't entirely
> correct, and reworked the entry code to fix this. As of commit:
> 
>   23529049c6842382 ("arm64: entry: fix non-NMI user<->kernel transitions")
> 
> ... we consistently call context_tracking_user_exit() later as part of
> ret_to_user. Prior to this we can transiently unmask exceptions (e.g. as
> part of do_notify_resume), and we always mask all exceptions prior to
> calling context_tracking_user_exit().
> 
> Thus, there's no longer a reason to leave IRQs or FIQs masked at the end
> of el0_dbg() or el0_error(), so let's bring these into line with other
> EL0 exceptions handlers and unmask all exceptions after the handler is
> finished.
> 

We discussed some changes to the commit message offline, otherwise:

Reviewed-by: Joey Gouly <joey.gouly@arm.com>

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  reply	other threads:[~2021-05-25 17:03 UTC|newest]

Thread overview: 40+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2021-05-19 12:38 [PATCH v2 00/19] arm64: entry: migrate more code to C Mark Rutland
2021-05-19 12:38 ` [PATCH v2 01/19] arm64: remove redundant local_daif_mask() in bad_mode() Mark Rutland
2021-05-21 10:39   ` Joey Gouly
2021-05-19 12:38 ` [PATCH v2 02/19] arm64: entry: unmask IRQ+FIQ after EL0 handling Mark Rutland
2021-05-25 16:45   ` Joey Gouly [this message]
2021-05-19 12:38 ` [PATCH v2 03/19] arm64: entry: convert SError handlers to C Mark Rutland
2021-05-25 13:38   ` Joey Gouly
2021-05-19 12:38 ` [PATCH v2 04/19] arm64: entry: move arm64_preempt_schedule_irq to entry-common.c Mark Rutland
2021-05-21 11:00   ` Joey Gouly
2021-05-19 12:38 ` [PATCH v2 05/19] arm64: entry: move preempt logic to C Mark Rutland
2021-05-25 12:50   ` Joey Gouly
2021-05-19 12:38 ` [PATCH v2 06/19] arm64: entry: add a call_on_irq_stack helper Mark Rutland
2021-05-19 14:46   ` Mark Rutland
2021-05-19 12:38 ` [PATCH v2 07/19] arm64: entry: convert IRQ+FIQ handlers to C Mark Rutland
2021-05-21 13:19   ` Joey Gouly
2021-05-21 15:23     ` Mark Rutland
2021-05-19 12:38 ` [PATCH v2 08/19] arm64: entry: organise entry handlers consistently Mark Rutland
2021-05-21 16:04   ` Joey Gouly
2021-05-19 12:38 ` [PATCH v2 09/19] arm64: entry: organise entry vectors consistently Mark Rutland
2021-05-21 16:07   ` Joey Gouly
2021-05-19 12:38 ` [PATCH v2 10/19] arm64: entry: consolidate EL1 exception returns Mark Rutland
2021-05-21 16:22   ` Joey Gouly
2021-05-19 12:38 ` [PATCH v2 11/19] arm64: entry: move bad_mode() to entry-common.c Mark Rutland
2021-05-21 16:46   ` Joey Gouly
2021-05-19 12:38 ` [PATCH v2 12/19] arm64: entry: improve bad_mode() Mark Rutland
2021-05-21 17:02   ` Joey Gouly
2021-05-21 17:10     ` Mark Rutland
2021-05-19 12:38 ` [PATCH v2 13/19] arm64: entry: template the entry asm functions Mark Rutland
2021-05-21 17:16   ` Joey Gouly
2021-05-19 12:38 ` [PATCH v2 14/19] arm64: entry: handle all vectors with C Mark Rutland
2021-05-21 15:59   ` Joey Gouly
2021-05-21 16:41     ` Mark Rutland
2021-05-19 12:38 ` [PATCH v2 15/19] arm64: entry: split bad stack entry Mark Rutland
2021-05-25 11:25   ` Joey Gouly
2021-05-19 12:38 ` [PATCH v2 16/19] arm64: entry: split SDEI entry Mark Rutland
2021-05-25 11:49   ` Joey Gouly
2021-05-19 12:39 ` [PATCH v2 17/19] arm64: entry: make NMI entry/exit functions static Mark Rutland
2021-05-21 17:21   ` Joey Gouly
2021-05-19 12:39 ` [PATCH v2 18/19] arm64: entry: don't instrument entry code with KCOV Mark Rutland
2021-05-19 12:39 ` [PATCH v2 19/19] arm64: idle: don't instrument idle " Mark Rutland

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