From: Catalin Marinas <catalin.marinas@arm.com>
To: "David Hildenbrand (Arm)" <david@kernel.org>
Cc: Muhammad Usama Anjum <usama.anjum@arm.com>,
Will Deacon <will@kernel.org>,
"Matthew Wilcox (Oracle)" <willy@infradead.org>,
Thomas Huth <thuth@redhat.com>,
Andrew Morton <akpm@linux-foundation.org>,
Lance Yang <lance.yang@linux.dev>,
Yeoreum Yun <yeoreum.yun@arm.com>,
linux-arm-kernel@lists.infradead.org,
linux-kernel@vger.kernel.org
Subject: Re: [PATCH] arm64: mte: Skip TFSR_EL1 checks and barriers in synchronous tag check mode
Date: Thu, 9 Apr 2026 17:27:30 +0100 [thread overview]
Message-ID: <adfTco5h9P3kV9QT@arm.com> (raw)
In-Reply-To: <c347fdc9-90b4-43ac-8c2e-559248777ba8@kernel.org>
On Wed, Mar 25, 2026 at 12:46:40PM +0100, David Hildenbrand wrote:
> On 3/11/26 18:50, Muhammad Usama Anjum wrote:
> > In MTE synchronous mode, tag check faults are reported as immediate
> > Data Abort exceptions. The TFSR_EL1.TF1 bit is never set, since faults
> > never go through the asynchronous path. Therefore, reading TFSR_EL1
> > and executing data and instruction barriers on kernel entry, exit,
> > context switch, and suspend is unnecessary overhead in sync mode.
> >
> > The exit path (mte_check_tfsr_exit) and the assembly paths
> > (check_mte_async_tcf / clear_mte_async_tcf in entry.S) already had this
> > check.
>
> Right, that's for user space (TFSR_EL1.TF0 IIUC). What you are adding is
> for KASAN. Maybe make that clearer.
Yeah, I'll tweak the commit message a bit. Even
system_uses_mte_async_or_asymm_mode() should be renamed to something
resembling kasan but I'll leave the function name as is for now.
--
Catalin
next prev parent reply other threads:[~2026-04-09 16:27 UTC|newest]
Thread overview: 6+ messages / expand[flat|nested] mbox.gz Atom feed top
2026-03-11 17:50 [PATCH] arm64: mte: Skip TFSR_EL1 checks and barriers in synchronous tag check mode Muhammad Usama Anjum
2026-03-12 6:48 ` Yeoreum Yun
2026-03-19 10:58 ` Muhammad Usama Anjum
2026-03-25 11:46 ` David Hildenbrand (Arm)
2026-04-09 16:27 ` Catalin Marinas [this message]
2026-04-09 18:34 ` Catalin Marinas
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