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Message-ID: <PH0PR21MB3025F5AADF3CCEF714585912D7FC9@PH0PR21MB3025.namprd21.prod.outlook.com> Date: Fri, 29 Apr 2022 16:26:02 +0000 From: "Michael Kelley (LINUX)" <mikelley@...rosoft.com> To: "Guilherme G. Piccoli" <gpiccoli@...lia.com>, "akpm@...ux-foundation.org" <akpm@...ux-foundation.org>, "bhe@...hat.com" <bhe@...hat.com>, "pmladek@...e.com" <pmladek@...e.com>, "kexec@...ts.infradead.org" <kexec@...ts.infradead.org> CC: "linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>, "bcm-kernel-feedback-list@...adcom.com" <bcm-kernel-feedback-list@...adcom.com>, "coresight@...ts.linaro.org" <coresight@...ts.linaro.org>, "linuxppc-dev@...ts.ozlabs.org" <linuxppc-dev@...ts.ozlabs.org>, "linux-alpha@...r.kernel.org" <linux-alpha@...r.kernel.org>, "linux-arm-kernel@...ts.infradead.org" <linux-arm-kernel@...ts.infradead.org>, "linux-edac@...r.kernel.org" <linux-edac@...r.kernel.org>, "linux-hyperv@...r.kernel.org" <linux-hyperv@...r.kernel.org>, "linux-leds@...r.kernel.org" <linux-leds@...r.kernel.org>, "linux-mips@...r.kernel.org" <linux-mips@...r.kernel.org>, "linux-parisc@...r.kernel.org" <linux-parisc@...r.kernel.org>, "linux-pm@...r.kernel.org" <linux-pm@...r.kernel.org>, "linux-remoteproc@...r.kernel.org" <linux-remoteproc@...r.kernel.org>, "linux-s390@...r.kernel.org" <linux-s390@...r.kernel.org>, "linux-tegra@...r.kernel.org" <linux-tegra@...r.kernel.org>, "linux-um@...ts.infradead.org" <linux-um@...ts.infradead.org>, "linux-xtensa@...ux-xtensa.org" <linux-xtensa@...ux-xtensa.org>, "netdev@...r.kernel.org" <netdev@...r.kernel.org>, "openipmi-developer@...ts.sourceforge.net" <openipmi-developer@...ts.sourceforge.net>, "rcu@...r.kernel.org" <rcu@...r.kernel.org>, "sparclinux@...r.kernel.org" <sparclinux@...r.kernel.org>, "xen-devel@...ts.xenproject.org" <xen-devel@...ts.xenproject.org>, "x86@...nel.org" <x86@...nel.org>, "kernel-dev@...lia.com" <kernel-dev@...lia.com>, "kernel@...ccoli.net" <kernel@...ccoli.net>, "halves@...onical.com" <halves@...onical.com>, "fabiomirmar@...il.com" <fabiomirmar@...il.com>, "alejandro.j.jimenez@...cle.com" <alejandro.j.jimenez@...cle.com>, "andriy.shevchenko@...ux.intel.com" <andriy.shevchenko@...ux.intel.com>, "arnd@...db.de" <arnd@...db.de>, "bp@...en8.de" <bp@...en8.de>, "corbet@....net" <corbet@....net>, "d.hatayama@...fujitsu.com" <d.hatayama@...fujitsu.com>, "dave.hansen@...ux.intel.com" <dave.hansen@...ux.intel.com>, "dyoung@...hat.com" <dyoung@...hat.com>, "feng.tang@...el.com" <feng.tang@...el.com>, "gregkh@...uxfoundation.org" <gregkh@...uxfoundation.org>, "hidehiro.kawai.ez@...achi.com" <hidehiro.kawai.ez@...achi.com>, "jgross@...e.com" <jgross@...e.com>, "john.ogness@...utronix.de" <john.ogness@...utronix.de>, "keescook@...omium.org" <keescook@...omium.org>, "luto@...nel.org" <luto@...nel.org>, "mhiramat@...nel.org" <mhiramat@...nel.org>, "mingo@...hat.com" <mingo@...hat.com>, "paulmck@...nel.org" <paulmck@...nel.org>, "peterz@...radead.org" <peterz@...radead.org>, "rostedt@...dmis.org" <rostedt@...dmis.org>, "senozhatsky@...omium.org" <senozhatsky@...omium.org>, "stern@...land.harvard.edu" <stern@...land.harvard.edu>, "tglx@...utronix.de" <tglx@...utronix.de>, "vgoyal@...hat.com" <vgoyal@...hat.com>, vkuznets <vkuznets@...hat.com>, "will@...nel.org" <will@...nel.org>, Marc Zyngier <maz@...nel.org>, Russell King <linux@...linux.org.uk> Subject: RE: [PATCH 02/30] ARM: kexec: Disable IRQs/FIQs also on crash CPUs shutdown path From: Guilherme G. Piccoli <gpiccoli@...lia.com> Sent: Wednesday, April 27, 2022 3:49 PM > > Currently the regular CPU shutdown path for ARM disables IRQs/FIQs > in the secondary CPUs - smp_send_stop() calls ipi_cpu_stop(), which > is responsible for that. This makes sense, since we're turning off > such CPUs, putting them in an endless busy-wait loop. > > Problem is that there is an alternative path for disabling CPUs, > in the form of function crash_smp_send_stop(), used for kexec/panic > paths. This functions relies in a SMP call that also triggers a s/functions relies in/function relies on/ > busy-wait loop [at machine_crash_nonpanic_core()], but *without* > disabling interrupts. This might lead to odd scenarios, like early > interrupts in the boot of kexec'd kernel or even interrupts in > other CPUs while the main one still works in the panic path and > assumes all secondary CPUs are (really!) off. > > This patch mimics the ipi_cpu_stop() interrupt disable mechanism > in the crash CPU shutdown path, hence disabling IRQs/FIQs in all > secondary CPUs in the kexec/panic path as well. > > Cc: Marc Zyngier <maz@...nel.org> > Cc: Russell King <linux@...linux.org.uk> > Signed-off-by: Guilherme G. Piccoli <gpiccoli@...lia.com> > --- > arch/arm/kernel/machine_kexec.c | 3 +++ > 1 file changed, 3 insertions(+) > > diff --git a/arch/arm/kernel/machine_kexec.c b/arch/arm/kernel/machine_kexec.c > index f567032a09c0..ef788ee00519 100644 > --- a/arch/arm/kernel/machine_kexec.c > +++ b/arch/arm/kernel/machine_kexec.c > @@ -86,6 +86,9 @@ void machine_crash_nonpanic_core(void *unused) > set_cpu_online(smp_processor_id(), false); > atomic_dec(&waiting_for_crash_ipi); > > + local_fiq_disable(); > + local_irq_disable(); > + > while (1) { > cpu_relax(); > wfe(); > -- > 2.36.0
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