From: Ard Biesheuvel <ardb@kernel.org>
To: Russell King - ARM Linux admin <linux@armlinux.org.uk>
Cc: Marc Zyngier <maz@kernel.org>,
Linus Walleij <linus.walleij@linaro.org>,
Android Kernel Team <kernel-team@android.com>,
Linux ARM <linux-arm-kernel@lists.infradead.org>,
Nicolas Pitre <nico@fluxnic.net>
Subject: Re: [PATCH v2 3/3] ARM: cache-v7: get rid of mini-stack
Date: Mon, 1 Mar 2021 17:10:01 +0100 [thread overview]
Message-ID: <CAMj1kXENMoqQcoEL4TfLFcqjt-2GpMBp4XbWbof-qFCtRvr8rg@mail.gmail.com> (raw)
In-Reply-To: <20210301155339.GW1463@shell.armlinux.org.uk>
On Mon, 1 Mar 2021 at 16:53, Russell King - ARM Linux admin
<linux@armlinux.org.uk> wrote:
>
> On Wed, Feb 10, 2021 at 07:55:32PM +0100, Ard Biesheuvel wrote:
> > Now that we have reduced the number of registers that we need to
> > preserve when calling v7_invalidate_l1 from the boot code, we can use
> > scratch registers to preserve the remaining ones, and get rid of the
> > mini stack entirely. This works around any issues regarding cache
> > behavior in relation to the uncached accesses to this memory, which is
> > hard to get right in the general case (i.e., both bare metal and under
> > virtualization)
> >
> > While at it, switch v7_invalidate_l1 to using ip as a scratch register
> > instead of r4. This makes the function AAPCS compliant, and removes the
> > need to stash r4 in ip across the call.
>
> You don't mention that we only do this for MP capable cores, which
> is in itself quite a big change - maybe that change should be a
> separate commit?
>
I'm not quite sure I understand what you are referring to here. All
call sites are updated to use the macro to call v7_invalidate_l1(), so
I don't think the UP-only and SMP-capable setup() paths are treated
any differently.
_______________________________________________
linux-arm-kernel mailing list
linux-arm-kernel@lists.infradead.org
http://lists.infradead.org/mailman/listinfo/linux-arm-kernel
next prev parent reply other threads:[~2021-03-01 16:11 UTC|newest]
Thread overview: 7+ messages / expand[flat|nested] mbox.gz Atom feed top
2021-02-10 18:55 [PATCH v2 0/3] ARM: v7: get rid of boot time mini stack Ard Biesheuvel
2021-02-10 18:55 ` [PATCH v2 1/3] ARM: cache-v7: add missing ISB after cache level selection Ard Biesheuvel
2021-02-10 18:55 ` [PATCH v2 2/3] ARM: cache-v7: refactor v7_invalidate_l1 to avoid clobbering r5/r6 Ard Biesheuvel
2021-02-10 18:55 ` [PATCH v2 3/3] ARM: cache-v7: get rid of mini-stack Ard Biesheuvel
2021-03-01 15:53 ` Russell King - ARM Linux admin
2021-03-01 16:10 ` Ard Biesheuvel [this message]
2021-03-01 14:38 ` [PATCH v2 0/3] ARM: v7: get rid of boot time mini stack Linus Walleij
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=CAMj1kXENMoqQcoEL4TfLFcqjt-2GpMBp4XbWbof-qFCtRvr8rg@mail.gmail.com \
--to=ardb@kernel.org \
--cc=kernel-team@android.com \
--cc=linus.walleij@linaro.org \
--cc=linux-arm-kernel@lists.infradead.org \
--cc=linux@armlinux.org.uk \
--cc=maz@kernel.org \
--cc=nico@fluxnic.net \
/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 an external index of several public inboxes,
see mirroring instructions on how to clone and mirror
all data and code used by this external index.