From: John David Anglin <dave.anglin@bell.net>
To: Helge Deller <deller@gmx.de>,
linux-parisc <linux-parisc@vger.kernel.org>
Cc: deller@kernel.org
Subject: Re: fixmap problem on PA11 hardware
Date: Sun, 31 Oct 2021 19:56:53 -0400 [thread overview]
Message-ID: <86ce35e1-7ef0-1f5c-5cbe-a498a280be29@bell.net> (raw)
In-Reply-To: <c25d8ffb-be2b-fb56-f0c9-11323d256a15@gmx.de>
On 2021-10-31 7:07 p.m., Helge Deller wrote:
> On 10/31/21 23:47, John David Anglin wrote:
>> My sense is the invalidate patch isn't correct. The main difference between pdc and fdc is that
>> it is optional whether pdc writes the cache line back to memory when it's dirty at priority 0.
> That's true, nevertheless I've seen different behaviour on real hardware.
>
> It might be, that:
>
> - flush_kernel_vmap_range((void *)fixmap, (p-fixmap) * sizeof(*p));
> + invalidate_kernel_vmap_range((void *)fixmap, (p-fixmap) * sizeof(*p));
> (here the flush might be sufficient)
> if (mapped)
> patch_unmap(FIX_TEXT_POKE0, &flags);
> + invalidate_kernel_vmap_range((void *)start, end - start);
> (but here the pdc is necessary to actually drop data from I-cache)
> flush_icache_range(start, end);
>
> I can test tomorrow...
Maybe sync is needed before releasing lock. pdc/fdc are weakly ordered.
Dave
--
John David Anglin dave.anglin@bell.net
next prev parent reply other threads:[~2021-10-31 23:56 UTC|newest]
Thread overview: 10+ messages / expand[flat|nested] mbox.gz Atom feed top
2021-10-27 19:09 fixmap problem on PA11 hardware Helge Deller
2021-10-27 20:14 ` John David Anglin
2021-10-31 21:22 ` Helge Deller
2021-10-31 22:47 ` John David Anglin
2021-10-31 23:07 ` Helge Deller
2021-10-31 23:56 ` John David Anglin [this message]
2021-11-01 0:01 ` John David Anglin
2021-11-01 0:06 ` John David Anglin
2021-11-01 18:09 ` Helge Deller
2021-11-02 21:25 ` John David Anglin
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