From: Catalin Marinas <catalin.marinas@arm.com>
To: Peter Collingbourne <pcc@google.com>
Cc: Linux ARM <linux-arm-kernel@lists.infradead.org>
Subject: Re: [PATCH] arm64: mte: optimize asynchronous tag check fault flag check
Date: Wed, 18 Nov 2020 17:07:50 +0000 [thread overview]
Message-ID: <X7VU5vpSCkfMBFvV@trantor> (raw)
In-Reply-To: <CAMn1gO7rGqNpF0wrdQhMexkhJUh8+vpkzsdZa=rZgSRVGobLrw@mail.gmail.com>
On Wed, Nov 18, 2020 at 08:53:16AM -0800, Peter Collingbourne wrote:
> On Wed, Nov 18, 2020 at 3:24 AM Catalin Marinas <catalin.marinas@arm.com> wrote:
> > On Tue, Nov 17, 2020 at 07:20:51PM -0800, Peter Collingbourne wrote:
> > > diff --git a/arch/arm64/kernel/syscall.c b/arch/arm64/kernel/syscall.c
> > > index e4c0dadf0d92..f533e83fd722 100644
> > > --- a/arch/arm64/kernel/syscall.c
> > > +++ b/arch/arm64/kernel/syscall.c
> > > @@ -123,7 +123,7 @@ static void el0_svc_common(struct pt_regs *regs, int scno, int sc_nr,
> > > local_daif_restore(DAIF_PROCCTX);
> > > user_exit();
> > >
> > > - if (system_supports_mte() && (flags & _TIF_MTE_ASYNC_FAULT)) {
> > > + if (IS_ENABLED(CONFIG_ARM64_MTE) && (flags & _TIF_MTE_ASYNC_FAULT)) {
[...]
> > That said, I'm happy to take this patch, most likely it replaces some
> > static branch with tbnz on this path. Given that MTE is on in defconfig,
> > do we actually need the IS_ENABLED() check? If we remove it, it would be
> > more consistent with the similar check in do_notify_resume().
>
> If we don't mind the additional conditional branch on
> CONFIG_ARM64_MTE=n kernels we don't need the IS_ENABLED() check. I'll
> remove it.
No need to, I'll do it when applying the patch.
--
Catalin
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next prev parent reply other threads:[~2020-11-18 17:08 UTC|newest]
Thread overview: 5+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-11-18 3:20 [PATCH] arm64: mte: optimize asynchronous tag check fault flag check Peter Collingbourne
2020-11-18 11:23 ` Catalin Marinas
2020-11-18 16:53 ` Peter Collingbourne
2020-11-18 17:07 ` Catalin Marinas [this message]
2020-11-18 17:48 ` Catalin Marinas
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