From mboxrd@z Thu Jan 1 00:00:00 1970 From: Michael Kelley (LINUX) Date: Fri, 29 Apr 2022 16:26:02 +0000 Subject: [PATCH 02/30] ARM: kexec: Disable IRQs/FIQs also on crash CPUs shutdown path In-Reply-To: <20220427224924.592546-3-gpiccoli@igalia.com> References: <20220427224924.592546-1-gpiccoli@igalia.com> <20220427224924.592546-3-gpiccoli@igalia.com> Message-ID: List-Id: MIME-Version: 1.0 Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit To: kexec@lists.infradead.org From: Guilherme G. Piccoli 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 > Cc: Russell King > Signed-off-by: Guilherme G. Piccoli > --- > 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