From: Sebastian Andrzej Siewior <bigeasy@linutronix.de>
To: Xie Yuanbin <xieyuanbin1@huawei.com>
Cc: rmk+kernel@armlinux.org.uk, linux@armlinux.org.uk,
rppt@kernel.org, vbabka@suse.cz, pfalcato@suse.de,
brauner@kernel.org, lorenzo.stoakes@oracle.com,
kuninori.morimoto.gx@renesas.com, tony@atomide.com,
arnd@arndb.de, akpm@linux-foundation.org, punitagrawal@gmail.com,
rjw@rjwysocki.net, marc.zyngier@arm.com, will@kernel.org,
linux-arm-kernel@lists.infradead.org,
linux-kernel@vger.kernel.org, liaohua4@huawei.com,
lilinjie8@huawei.com
Subject: Re: [PATCH v2 RESEND 1/2] ARM: spectre-v2: Fix potential missing mitigations
Date: Tue, 28 Oct 2025 17:20:05 +0100 [thread overview]
Message-ID: <20251028162005.bLKC89Hy@linutronix.de> (raw)
In-Reply-To: <20251016121622.8957-1-xieyuanbin1@huawei.com>
On 2025-10-16 20:16:21 [+0800], Xie Yuanbin wrote:
> Over the past six years, there have been continuous reports of this bug:
…
> 2019.3.19 https://lore.kernel.org/all/20190319203239.gl46fxnfz6gzeeic@linutronix.de/
>
> To fix it, we must check whether mitigation are needed before enabling
> interrupt(with PREEMPT) or before calling mm_read_lock()(without PREEMPT).
>
> Fixes: f5fe12b1eaee ("ARM: spectre-v2: harden user aborts in kernel space")
Hmm.
I was moving things back in 2019 but things shifted and this is no
longer required. If I apply both patches (of yours) then it sends a
signal with disabled interrupts which breaks my PREEMPT_RT case.
The requirement is to invoke the mitigation callback of the right CPU.
What about disabling preemption before getting the callback and doing
the invocation?
Sebastian
next prev parent reply other threads:[~2025-10-28 16:20 UTC|newest]
Thread overview: 7+ messages / expand[flat|nested] mbox.gz Atom feed top
2025-10-16 12:16 [PATCH v2 RESEND 1/2] ARM: spectre-v2: Fix potential missing mitigations Xie Yuanbin
2025-10-16 12:16 ` [PATCH v2 RESEND 2/2] ARM: mm: Optimize page_fault to reduce the impact of spectre-v2 bugfix Xie Yuanbin
2025-10-28 16:20 ` Sebastian Andrzej Siewior [this message]
2025-10-28 16:28 ` [PATCH v2 RESEND 1/2] ARM: spectre-v2: Fix potential missing mitigations Sebastian Andrzej Siewior
2025-10-28 18:20 ` Sebastian Andrzej Siewior
2025-10-29 2:41 ` Xie Yuanbin
2025-10-29 7:11 ` Sebastian Andrzej Siewior
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