From: Sumit Garg <sumit.garg@linaro.org>
To: Marc Zyngier <maz@kernel.org>
Cc: Mark Rutland <mark.rutland@arm.com>,
Daniel Thompson <daniel.thompson@linaro.org>,
Jason Cooper <jason@lakedaemon.net>,
Catalin Marinas <catalin.marinas@arm.com>,
ito-yuichi@fujitsu.com, Douglas Anderson <dianders@chromium.org>,
Linux Kernel Mailing List <linux-kernel@vger.kernel.org>,
julien.thierry.kdev@gmail.com,
Jason Wessel <jason.wessel@windriver.com>,
kgdb-bugreport@lists.sourceforge.net,
Thomas Gleixner <tglx@linutronix.de>,
Masayoshi Mizuma <msys.mizuma@gmail.com>,
Will Deacon <will@kernel.org>,
linux-arm-kernel <linux-arm-kernel@lists.infradead.org>
Subject: Re: [PATCH v5 5/5] arm64: ipi_nmi: Add support for NMI backtrace
Date: Tue, 20 Oct 2020 14:43:54 +0530 [thread overview]
Message-ID: <CAFA6WYMe02J6Laa0PWDW4849KGnw8Hu2H5d6UfppeaaE4-Z0vw@mail.gmail.com> (raw)
In-Reply-To: <d4a4a37b93f34da79b87519181bffb97@kernel.org>
On Mon, 19 Oct 2020 at 17:50, Marc Zyngier <maz@kernel.org> wrote:
>
> On 2020-10-14 12:12, Sumit Garg wrote:
> > Enable NMI backtrace support on arm64 using IPI turned as an NMI
> > leveraging pseudo NMIs support. It is now possible for users to get a
> > backtrace of a CPU stuck in hard-lockup using magic SYSRQ.
> >
> > Signed-off-by: Sumit Garg <sumit.garg@linaro.org>
> > ---
> > arch/arm64/include/asm/irq.h | 6 ++++++
> > arch/arm64/kernel/ipi_nmi.c | 12 +++++++++++-
> > 2 files changed, 17 insertions(+), 1 deletion(-)
> >
> > diff --git a/arch/arm64/include/asm/irq.h
> > b/arch/arm64/include/asm/irq.h
> > index b2b0c64..e840bf1 100644
> > --- a/arch/arm64/include/asm/irq.h
> > +++ b/arch/arm64/include/asm/irq.h
> > @@ -6,6 +6,12 @@
> >
> > #include <asm-generic/irq.h>
> >
> > +#ifdef CONFIG_SMP
> > +extern void arch_trigger_cpumask_backtrace(const cpumask_t *mask,
> > + bool exclude_self);
> > +#define arch_trigger_cpumask_backtrace arch_trigger_cpumask_backtrace
> > +#endif
> > +
> > struct pt_regs;
> >
> > static inline int nr_legacy_irqs(void)
> > diff --git a/arch/arm64/kernel/ipi_nmi.c b/arch/arm64/kernel/ipi_nmi.c
> > index e0a9e03..e1dc19d 100644
> > --- a/arch/arm64/kernel/ipi_nmi.c
> > +++ b/arch/arm64/kernel/ipi_nmi.c
> > @@ -9,6 +9,7 @@
> > #include <linux/interrupt.h>
> > #include <linux/irq.h>
> > #include <linux/kgdb.h>
> > +#include <linux/nmi.h>
> > #include <linux/smp.h>
> >
> > #include <asm/nmi.h>
> > @@ -25,12 +26,21 @@ void arch_send_call_nmi_func_ipi_mask(cpumask_t
> > *mask)
> > __ipi_send_mask(ipi_desc, mask);
> > }
> >
> > +void arch_trigger_cpumask_backtrace(const cpumask_t *mask, bool
> > exclude_self)
> > +{
> > + nmi_trigger_cpumask_backtrace(mask, exclude_self,
> > + arch_send_call_nmi_func_ipi_mask);
> > +}
> > +
> > static irqreturn_t ipi_nmi_handler(int irq, void *data)
> > {
> > unsigned int cpu = smp_processor_id();
> >
> > - ipi_kgdb_nmicallback(cpu, get_irq_regs());
> > + if (nmi_cpu_backtrace(get_irq_regs()))
> > + goto out;
> >
> > + ipi_kgdb_nmicallback(cpu, get_irq_regs());
> > +out:
> > return IRQ_HANDLED;
> > }
>
> Can't you have *both* a request for a backtrace and a KGDB call?
> It really shouldn't be either/or. It also outlines how well shared
> interrupts work with edge triggered signalling...
Unfortunately, NMIs doesn't seem to support shared mode [1].
[1] https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/tree/kernel/irq/manage.c#n1480
-Sumit
>
> M.
> --
> Jazz is not dead. It just smells funny...
_______________________________________________
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:[~2020-10-20 9:16 UTC|newest]
Thread overview: 31+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-10-14 11:12 [PATCH v5 0/5] arm64: Add framework to turn an IPI as NMI Sumit Garg
2020-10-14 11:12 ` [PATCH v5 1/5] arm64: Add framework to turn " Sumit Garg
2020-10-15 1:15 ` Masayoshi Mizuma
2020-10-19 11:37 ` Marc Zyngier
2020-10-20 6:43 ` Sumit Garg
2020-10-20 10:08 ` Marc Zyngier
2020-10-20 11:22 ` Sumit Garg
2020-10-20 12:25 ` Daniel Thompson
2020-10-20 12:32 ` Marc Zyngier
2020-10-21 5:22 ` Sumit Garg
2020-10-21 10:27 ` Marc Zyngier
2020-10-22 11:52 ` Sumit Garg
2020-10-19 11:56 ` Marc Zyngier
2020-10-20 7:07 ` Sumit Garg
2020-10-14 11:12 ` [PATCH v5 2/5] irqchip/gic-v3: Enable support for SGIs to act as NMIs Sumit Garg
2020-10-15 1:16 ` Masayoshi Mizuma
2020-10-19 12:07 ` Marc Zyngier
2020-10-20 7:24 ` Sumit Garg
2020-10-14 11:12 ` [PATCH v5 3/5] arm64: smp: Allocate and setup IPI as NMI Sumit Garg
2020-10-15 1:16 ` Masayoshi Mizuma
2020-10-19 11:59 ` Marc Zyngier
2020-10-20 7:16 ` Sumit Garg
2020-10-14 11:12 ` [PATCH v5 4/5] arm64: kgdb: Round up cpus using " Sumit Garg
2020-10-19 12:15 ` Marc Zyngier
2020-10-20 8:51 ` Sumit Garg
2020-10-14 11:12 ` [PATCH v5 5/5] arm64: ipi_nmi: Add support for NMI backtrace Sumit Garg
2020-10-15 1:17 ` Masayoshi Mizuma
2020-10-19 12:20 ` Marc Zyngier
2020-10-20 9:13 ` Sumit Garg [this message]
2020-10-21 10:32 ` Marc Zyngier
2020-10-21 11:28 ` Sumit Garg
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=CAFA6WYMe02J6Laa0PWDW4849KGnw8Hu2H5d6UfppeaaE4-Z0vw@mail.gmail.com \
--to=sumit.garg@linaro.org \
--cc=catalin.marinas@arm.com \
--cc=daniel.thompson@linaro.org \
--cc=dianders@chromium.org \
--cc=ito-yuichi@fujitsu.com \
--cc=jason.wessel@windriver.com \
--cc=jason@lakedaemon.net \
--cc=julien.thierry.kdev@gmail.com \
--cc=kgdb-bugreport@lists.sourceforge.net \
--cc=linux-arm-kernel@lists.infradead.org \
--cc=linux-kernel@vger.kernel.org \
--cc=mark.rutland@arm.com \
--cc=maz@kernel.org \
--cc=msys.mizuma@gmail.com \
--cc=tglx@linutronix.de \
--cc=will@kernel.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).