All of lore.kernel.org
 help / color / mirror / Atom feed
From: Michael Ellerman <patch-notifications@ellerman.id.au>
To: Christophe Leroy <christophe.leroy@c-s.fr>,
	Benjamin Herrenschmidt <benh@kernel.crashing.org>,
	Paul Mackerras <paulus@samba.org>
Cc: linuxppc-dev@lists.ozlabs.org, linux-kernel@vger.kernel.org
Subject: Re: [PATCH] powerpc/32s: Fix CPU wake-up from sleep mode
Date: Tue,  4 Feb 2020 23:01:34 +1100 (AEDT)	[thread overview]
Message-ID: <48BjwG5Y3xzB3wq@ozlabs.org> (raw)
In-Reply-To: <6d02c3ae6ad77af34392e98117e44c2bf6d13ba1.1580121710.git.christophe.leroy@c-s.fr>

On Mon, 2020-01-27 at 10:42:04 UTC, Christophe Leroy wrote:
> Commit f7354ccac844 ("powerpc/32: Remove CURRENT_THREAD_INFO and
> rename TI_CPU") broke the CPU wake-up from sleep mode (i.e. when
> _TLF_SLEEPING is set) by delaying the tovirt(r2, r2).
> 
> This is because r2 is not restored by fast_exception_return. It used
> to work (by chance ?) because CPU wake-up interrupt never comes from
> user, so r2 is expected to point to 'current' on return.
> 
> Commit e2fb9f544431 ("powerpc/32: Prepare for Kernel Userspace Access
> Protection") broke it even more by clobbering r0 which is not
> restored by fast_exception_return either.
> 
> Use r6 instead of r0. This is possible because r3-r6 are restored by
> fast_exception_return and only r3-r5 are used for exception arguments.
> 
> For r2 it could be converted back to virtual address, but stay on the
> safe side and restore it from the stack instead. It should be live
> in the cache at that moment, so loading from the stack should make
> no difference compared to converting it from phys to virt.
> 
> Fixes: f7354ccac844 ("powerpc/32: Remove CURRENT_THREAD_INFO and rename TI_CPU")
> Fixes: e2fb9f544431 ("powerpc/32: Prepare for Kernel Userspace Access Protection")
> Cc: stable@vger.kernel.org
> Signed-off-by: Christophe Leroy <christophe.leroy@c-s.fr>

Applied to powerpc next, thanks.

https://git.kernel.org/powerpc/c/9933819099c4600b41a042f27a074470a43cf6b9

cheers

      reply	other threads:[~2020-02-04 12:01 UTC|newest]

Thread overview: 3+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2020-01-27 10:42 [PATCH] powerpc/32s: Fix CPU wake-up from sleep mode Christophe Leroy
2020-01-27 10:42 ` Christophe Leroy
2020-02-04 12:01 ` Michael Ellerman [this message]

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=48BjwG5Y3xzB3wq@ozlabs.org \
    --to=patch-notifications@ellerman.id.au \
    --cc=benh@kernel.crashing.org \
    --cc=christophe.leroy@c-s.fr \
    --cc=linux-kernel@vger.kernel.org \
    --cc=linuxppc-dev@lists.ozlabs.org \
    --cc=paulus@samba.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 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.