From: Sebastian Andrzej Siewior <bigeasy@linutronix.de>
To: Mark Rutland <mark.rutland@arm.com>
Cc: "Luis Claudio R. Goncalves" <lgoncalv@redhat.com>,
linux-arm-kernel@lists.infradead.org,
linux-rt-devel@lists.linux.dev,
Catalin Marinas <catalin.marinas@arm.com>,
Will Deacon <will@kernel.org>,
Steven Rostedt <rostedt@goodmis.org>,
Ryan Roberts <ryan.roberts@arm.com>,
Mark Brown <broonie@kernel.org>, Ard Biesheuvel <ardb@kernel.org>,
Joey Gouly <joey.gouly@arm.com>,
linux-kernel@vger.kernel.org
Subject: Re: BUG: debug_exception_enter() disables preemption and may call sleeping functions on aarch64 with RT
Date: Mon, 10 Feb 2025 15:06:57 +0100 [thread overview]
Message-ID: <20250210140657.UAsRw4k8@linutronix.de> (raw)
In-Reply-To: <Z6n16cK85JMyowDq@J2N7QTR9R3>
On 2025-02-10 12:49:45 [+0000], Mark Rutland wrote:
> Hi,
Hi,
> I don't have an immediate suggestion; I'll need to go think about this
> for a bit. Unfortunatealy, there are several nested cans of worms here.
> :/
>
> In theory, we can go split out the EL0 "debug exceptions" into separate
> handlers, and wouldn't generally need to disable preemption for things
> like BRK or single-step.
>
> However, it's not immediately clear to me how we could handle
> watchpoints or breakpoints, since for those preemption/interruption
> could change the HW state under our feet, and we rely on single-step to
> skip past the watchpoint/breakpoint after it is handled.
Couldn't you delay sending signals until after the preempt-disable
section?
> That, and last I looked reworking this we'd need to do a larger rework
> to split out those "debug exceptions" because of that way that currently
> bounces through the fault handling ligic in arch/arm64/mm/.
>
> Mark.
Sebastian
next prev parent reply other threads:[~2025-02-10 14:07 UTC|newest]
Thread overview: 9+ messages / expand[flat|nested] mbox.gz Atom feed top
2025-02-07 14:22 BUG: debug_exception_enter() disables preemption and may call sleeping functions on aarch64 with RT Luis Claudio R. Goncalves
2025-02-10 12:49 ` Mark Rutland
2025-02-10 14:06 ` Sebastian Andrzej Siewior [this message]
2025-02-12 0:48 ` Luis Claudio R. Goncalves
2025-02-12 11:21 ` Sebastian Andrzej Siewior
2025-02-11 14:34 ` Luis Claudio R. Goncalves
2025-02-12 0:35 ` Luis Claudio R. Goncalves
2025-02-12 12:40 ` Mark Rutland
2025-02-12 13:07 ` Mark Rutland
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