linux-kernel.vger.kernel.org archive mirror
 help / color / mirror / Atom feed
From: Will Deacon <will@kernel.org>
To: Daniel Thompson <daniel.thompson@linaro.org>
Cc: Catalin Marinas <catalin.marinas@arm.com>,
	Douglas Anderson <dianders@chromium.org>,
	Jason Wessel <jason.wessel@windriver.com>,
	linux-arm-kernel@lists.infradead.org,
	linux-kernel@vger.kernel.org, patches@linaro.org
Subject: Re: [PATCH v2] arm64: cacheflush: Fix KGDB trap detection
Date: Tue, 5 May 2020 16:09:16 +0100	[thread overview]
Message-ID: <20200505150916.GC24239@willie-the-truck> (raw)
In-Reply-To: <20200505141529.2qb35fbqudtac3ys@holly.lan>

On Tue, May 05, 2020 at 03:15:29PM +0100, Daniel Thompson wrote:
> On Mon, May 04, 2020 at 09:48:04PM +0100, Will Deacon wrote:
> > On Mon, May 04, 2020 at 06:05:18PM +0100, Daniel Thompson wrote:
> > > diff --git a/arch/arm64/include/asm/cacheflush.h b/arch/arm64/include/asm/cacheflush.h
> > > index e6cca3d4acf7..ce50c1f1f1ea 100644
> > > --- a/arch/arm64/include/asm/cacheflush.h
> > > +++ b/arch/arm64/include/asm/cacheflush.h
> > > @@ -79,7 +79,7 @@ static inline void flush_icache_range(unsigned long start, unsigned long end)
> > >  	 * IPI all online CPUs so that they undergo a context synchronization
> > >  	 * event and are forced to refetch the new instructions.
> > >  	 */
> > > -#ifdef CONFIG_KGDB
> > > +
> > >  	/*
> > >  	 * KGDB performs cache maintenance with interrupts disabled, so we
> > >  	 * will deadlock trying to IPI the secondary CPUs. In theory, we can
> > > @@ -89,9 +89,9 @@ static inline void flush_icache_range(unsigned long start, unsigned long end)
> > >  	 * the patching operation, so we don't need extra IPIs here anyway.
> > >  	 * In which case, add a KGDB-specific bodge and return early.
> > >  	 */
> > > -	if (kgdb_connected && irqs_disabled())
> > > +	if (in_dbg_master())
> > 
> > Does this imply that irqs are disabled?
> 
> Yes.
> 
> Assuming CONFIG_KGDB is enabled then in_dbg_master() expands to:
> 
>     (raw_smp_processor_id() == atomic_read(&kgdb_active))

Aha, so this can drop the raw_ prefix and call smp_processor_id() instead?
I can queue the arm64 patch regardless.

Cheers,

Will

  reply	other threads:[~2020-05-05 15:09 UTC|newest]

Thread overview: 6+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2020-05-04 17:05 [PATCH v2] arm64: cacheflush: Fix KGDB trap detection Daniel Thompson
2020-05-04 20:48 ` Will Deacon
2020-05-05 14:15   ` Daniel Thompson
2020-05-05 15:09     ` Will Deacon [this message]
2020-05-06 15:06       ` Daniel Thompson
2020-05-05 16:13 ` Will Deacon

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=20200505150916.GC24239@willie-the-truck \
    --to=will@kernel.org \
    --cc=catalin.marinas@arm.com \
    --cc=daniel.thompson@linaro.org \
    --cc=dianders@chromium.org \
    --cc=jason.wessel@windriver.com \
    --cc=linux-arm-kernel@lists.infradead.org \
    --cc=linux-kernel@vger.kernel.org \
    --cc=patches@linaro.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).