linux-arm-kernel.lists.infradead.org archive mirror
 help / color / mirror / Atom feed
From: Catalin Marinas <catalin.marinas@arm.com>
To: "Russell King (Oracle)" <linux@armlinux.org.uk>
Cc: Peter Zijlstra <peterz@infradead.org>,
	Andy Lutomirski <luto@kernel.org>,
	x86@kernel.org, Dave Hansen <dave.hansen@intel.com>,
	LKML <linux-kernel@vger.kernel.org>,
	linux-mm@kvack.org, Andrew Morton <akpm@linux-foundation.org>,
	Mathieu Desnoyers <mathieu.desnoyers@efficios.com>,
	Nicholas Piggin <npiggin@gmail.com>,
	linux-arm-kernel@lists.infradead.org,
	Will Deacon <will@kernel.org>
Subject: Re: [PATCH 7/8] membarrier: Remove arm (32) support for SYNC_CORE
Date: Wed, 16 Jun 2021 17:00:51 +0100	[thread overview]
Message-ID: <20210616160050.GE22433@arm.com> (raw)
In-Reply-To: <20210616154529.GD22433@arm.com>

On Wed, Jun 16, 2021 at 04:45:29PM +0100, Catalin Marinas wrote:
> On Wed, Jun 16, 2021 at 04:23:26PM +0100, Russell King wrote:
> > On Wed, Jun 16, 2021 at 04:04:56PM +0100, Catalin Marinas wrote:
> > > The simpler fix for flush_icache_range() is to disable preemption, read
> > > a word in a cacheline to force any dirty lines on another CPU to be
> > > evicted and then issue the D-cache maintenance (for those cache lines
> > > which are still dirty on the current CPU).
> > 
> > Is just reading sufficient? If so, why do we do a read-then-write in
> > the MPCore DMA cache ops? Don't we need the write to force exclusive
> > ownership? If we don't have exclusive ownership of the dirty line,
> > how can we be sure to write it out of the caches?
> 
> For cleaning (which is the case for I/D coherency), we only need reading
> since we are fine with clean lines being left in the D-cache on other
> CPUs. For invalidation, we indeed need to force the exclusive ownership,
> hence the write.

Ah, I'm not sure the I-cache is broadcast in hardware on ARM11MPCore
either. So fixing the D side won't be sufficient.

-- 
Catalin

_______________________________________________
linux-arm-kernel mailing list
linux-arm-kernel@lists.infradead.org
http://lists.infradead.org/mailman/listinfo/linux-arm-kernel

  reply	other threads:[~2021-06-16 16:02 UTC|newest]

Thread overview: 45+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
     [not found] <cover.1623813516.git.luto@kernel.org>
2021-06-16  3:21 ` [PATCH 7/8] membarrier: Remove arm (32) support for SYNC_CORE Andy Lutomirski
2021-06-16  9:28   ` Russell King (Oracle)
2021-06-16 10:16   ` Peter Zijlstra
2021-06-16 10:20     ` Peter Zijlstra
2021-06-16 10:34       ` Russell King (Oracle)
2021-06-16 11:10         ` Peter Zijlstra
2021-06-16 13:22           ` Russell King (Oracle)
2021-06-16 15:04             ` Catalin Marinas
2021-06-16 15:23               ` Russell King (Oracle)
2021-06-16 15:45                 ` Catalin Marinas
2021-06-16 16:00                   ` Catalin Marinas [this message]
2021-06-16 16:27                     ` Russell King (Oracle)
2021-06-17  8:55                       ` Krzysztof Hałasa
2021-06-18 12:54                       ` Linus Walleij
2021-06-18 13:19                         ` Russell King (Oracle)
2021-06-18 13:36                         ` Arnd Bergmann
2021-06-17 10:40   ` Mark Rutland
2021-06-17 11:23     ` Russell King (Oracle)
2021-06-17 11:33       ` Mark Rutland
2021-06-17 13:41         ` Andy Lutomirski
2021-06-17 13:51           ` Mark Rutland
2021-06-17 14:00             ` Andy Lutomirski
2021-06-17 14:20               ` Mark Rutland
2021-06-17 15:01               ` Peter Zijlstra
2021-06-17 15:13                 ` Peter Zijlstra
2021-06-17 14:16             ` Mathieu Desnoyers
2021-06-17 14:05           ` Peter Zijlstra
2021-06-18  0:07   ` Andy Lutomirski
2021-06-16  3:21 ` [PATCH 8/8] membarrier: Rewrite sync_core_before_usermode() and improve documentation Andy Lutomirski
2021-06-16  4:45   ` Nicholas Piggin
2021-06-16 18:52     ` Andy Lutomirski
2021-06-16 23:48       ` Andy Lutomirski
2021-06-18 15:27       ` Christophe Leroy
2021-06-16 10:20   ` Will Deacon
2021-06-16 23:58     ` Andy Lutomirski
2021-06-17 14:47   ` Mathieu Desnoyers
2021-06-18  0:12     ` Andy Lutomirski
2021-06-18 16:31       ` Mathieu Desnoyers
2021-06-18 19:58         ` Andy Lutomirski
2021-06-18 20:09           ` Mathieu Desnoyers
2021-06-19  6:02             ` Nicholas Piggin
2021-06-19 15:50               ` Andy Lutomirski
2021-06-20  2:10                 ` Nicholas Piggin
2021-06-17 15:16   ` Mathieu Desnoyers
2021-06-18  0:13     ` Andy Lutomirski

Reply instructions:

You may reply publicly to this message via plain-text email
using any one of the following methods:

* Save the following mbox file, import it into your mail client,
  and reply-to-all from there: mbox

  Avoid top-posting and favor interleaved quoting:
  https://en.wikipedia.org/wiki/Posting_style#Interleaved_style

* Reply using the --to, --cc, and --in-reply-to
  switches of git-send-email(1):

  git send-email \
    --in-reply-to=20210616160050.GE22433@arm.com \
    --to=catalin.marinas@arm.com \
    --cc=akpm@linux-foundation.org \
    --cc=dave.hansen@intel.com \
    --cc=linux-arm-kernel@lists.infradead.org \
    --cc=linux-kernel@vger.kernel.org \
    --cc=linux-mm@kvack.org \
    --cc=linux@armlinux.org.uk \
    --cc=luto@kernel.org \
    --cc=mathieu.desnoyers@efficios.com \
    --cc=npiggin@gmail.com \
    --cc=peterz@infradead.org \
    --cc=will@kernel.org \
    --cc=x86@kernel.org \
    /path/to/YOUR_REPLY

  https://kernel.org/pub/software/scm/git/docs/git-send-email.html

* If your mail client supports setting the In-Reply-To header
  via mailto: links, try the mailto: link
Be sure your reply has a Subject: header at the top and a blank line before the message body. 
This is a public inbox, see mirroring instructions
for how to clone and mirror all data and code used for this inbox;
as well as URLs for NNTP newsgroup(s).