From: Will Deacon <will@kernel.org>
To: Masami Hiramatsu <mhiramat@kernel.org>
Cc: Catalin Marinas <catalin.marinas@arm.com>,
Will Deacon <will.deacon@arm.com>, Dan Rue <dan.rue@linaro.org>,
Daniel Diaz <daniel.diaz@linaro.org>,
Anders Roxell <anders.roxell@linaro.org>,
Naresh Kamboju <naresh.kamboju@linaro.org>,
linux-kernel@vger.kernel.org, Matt Hart <matthew.hart@linaro.org>,
"Paul E . McKenney" <paulmck@linux.ibm.com>,
linux-arm-kernel@lists.infradead.org
Subject: Re: [PATCH v3 3/4] arm64: Make debug exception handlers visible from RCU
Date: Thu, 1 Aug 2019 08:37:37 +0100 [thread overview]
Message-ID: <20190801073737.wrhespf5xh3qudil@willie-the-truck> (raw)
In-Reply-To: <20190801143225.e61e38ce7a701407b19f8008@kernel.org>
Hi Masami,
On Thu, Aug 01, 2019 at 02:32:25PM +0900, Masami Hiramatsu wrote:
> On Wed, 31 Jul 2019 18:26:03 +0100
> Will Deacon <will@kernel.org> wrote:
> > On Thu, Jul 25, 2019 at 05:16:15PM +0900, Masami Hiramatsu wrote:
> > > diff --git a/arch/arm64/mm/fault.c b/arch/arm64/mm/fault.c
> > > index 9568c116ac7f..ed6c55c87fdc 100644
> > > --- a/arch/arm64/mm/fault.c
> > > +++ b/arch/arm64/mm/fault.c
> > > @@ -777,6 +777,42 @@ void __init hook_debug_fault_code(int nr,
> > > debug_fault_info[nr].name = name;
> > > }
> > >
> > > +/*
> > > + * In debug exception context, we explicitly disable preemption.
> >
> > Maybe add "despite having interrupts disabled"?
>
> OK, I'll add it.
>
> > > + * This serves two purposes: it makes it much less likely that we would
> > > + * accidentally schedule in exception context and it will force a warning
> > > + * if we somehow manage to schedule by accident.
> > > + */
> > > +static void debug_exception_enter(struct pt_regs *regs)
> > > +{
> > > + if (user_mode(regs)) {
> > > + RCU_LOCKDEP_WARN(!rcu_is_watching(), "entry code didn't wake RCU");
> > > + } else {
> > > + /*
> > > + * We might have interrupted pretty much anything. In
> > > + * fact, if we're a debug exception, we can even interrupt
> > > + * NMI processing. We don't want this code makes in_nmi()
> > > + * to return true, but we need to notify RCU.
> > > + */
> > > + rcu_nmi_enter();
> > > + }
> > > +
> > > + preempt_disable();
> >
> > If you're addingt new functions for entry/exit, maybe move the
> > trace_hardirqs_{on,off}() calls in here too?
>
> OK, let's move it in these functions.
Brill, thanks. Please just resend this patch, as I can pick the other three
up as they are.
Will
next prev parent reply other threads:[~2019-08-01 7:37 UTC|newest]
Thread overview: 12+ messages / expand[flat|nested] mbox.gz Atom feed top
2019-07-25 8:15 [PATCH v3 0/4] arm64: kprobes: Fix some bugs in arm64 kprobes Masami Hiramatsu
2019-07-25 8:15 ` [PATCH v3 1/4] arm64: kprobes: Recover pstate.D in single-step exception handler Masami Hiramatsu
2019-08-01 12:16 ` Will Deacon
2019-08-01 14:08 ` Masami Hiramatsu
2019-08-01 14:25 ` [PATCH v4] " Masami Hiramatsu
2019-07-25 8:16 ` [PATCH v3 2/4] arm64: unwind: Prohibit probing on return_address() Masami Hiramatsu
2019-07-25 8:16 ` [PATCH v3 3/4] arm64: Make debug exception handlers visible from RCU Masami Hiramatsu
2019-07-31 17:26 ` Will Deacon
2019-08-01 5:32 ` Masami Hiramatsu
2019-08-01 7:37 ` Will Deacon [this message]
2019-08-01 14:36 ` [PATCH v4] " Masami Hiramatsu
2019-07-25 8:16 ` [PATCH v3 4/4] arm64: Remove unneeded rcu_read_lock from debug handlers Masami Hiramatsu
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=20190801073737.wrhespf5xh3qudil@willie-the-truck \
--to=will@kernel.org \
--cc=anders.roxell@linaro.org \
--cc=catalin.marinas@arm.com \
--cc=dan.rue@linaro.org \
--cc=daniel.diaz@linaro.org \
--cc=linux-arm-kernel@lists.infradead.org \
--cc=linux-kernel@vger.kernel.org \
--cc=matthew.hart@linaro.org \
--cc=mhiramat@kernel.org \
--cc=naresh.kamboju@linaro.org \
--cc=paulmck@linux.ibm.com \
--cc=will.deacon@arm.com \
/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).