c814ca029e
PSCIv0.2 adds a new function called AFFINITY_INFO, which can be used to query if a specified CPU has actually gone offline. Calling this function via cpu_kill ensures that a CPU has quiesced after a call to cpu_die. This helps prevent the CPU from doing arbitrary bad things when data or instructions are clobbered (as happens with kexec) in the window between a CPU announcing that it is dead and said CPU leaving the kernel. Signed-off-by: Ashwin Chaugule <ashwin.chaugule@linaro.org> Signed-off-by: Mark Rutland <mark.rutland@arm.com> Reviewed-by: Rob Herring <robh@kernel.org> Acked-by: Catalin Marinas <catalin.marinas@arm.com>
115 lines
3 KiB
C
115 lines
3 KiB
C
/*
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* This program is free software; you can redistribute it and/or modify
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* it under the terms of the GNU General Public License version 2 as
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* published by the Free Software Foundation.
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*
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* This program is distributed in the hope that it will be useful,
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* but WITHOUT ANY WARRANTY; without even the implied warranty of
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* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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* GNU General Public License for more details.
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*
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* Copyright (C) 2012 ARM Limited
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*
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* Author: Will Deacon <will.deacon@arm.com>
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*/
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#include <linux/init.h>
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#include <linux/smp.h>
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#include <linux/of.h>
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#include <linux/delay.h>
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#include <uapi/linux/psci.h>
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#include <asm/psci.h>
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#include <asm/smp_plat.h>
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/*
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* psci_smp assumes that the following is true about PSCI:
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*
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* cpu_suspend Suspend the execution on a CPU
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* @state we don't currently describe affinity levels, so just pass 0.
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* @entry_point the first instruction to be executed on return
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* returns 0 success, < 0 on failure
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*
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* cpu_off Power down a CPU
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* @state we don't currently describe affinity levels, so just pass 0.
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* no return on successful call
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*
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* cpu_on Power up a CPU
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* @cpuid cpuid of target CPU, as from MPIDR
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* @entry_point the first instruction to be executed on return
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* returns 0 success, < 0 on failure
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*
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* migrate Migrate the context to a different CPU
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* @cpuid cpuid of target CPU, as from MPIDR
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* returns 0 success, < 0 on failure
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*
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*/
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extern void secondary_startup(void);
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static int psci_boot_secondary(unsigned int cpu, struct task_struct *idle)
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{
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if (psci_ops.cpu_on)
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return psci_ops.cpu_on(cpu_logical_map(cpu),
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__pa(secondary_startup));
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return -ENODEV;
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}
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#ifdef CONFIG_HOTPLUG_CPU
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void __ref psci_cpu_die(unsigned int cpu)
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{
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const struct psci_power_state ps = {
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.type = PSCI_POWER_STATE_TYPE_POWER_DOWN,
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};
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if (psci_ops.cpu_off)
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psci_ops.cpu_off(ps);
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/* We should never return */
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panic("psci: cpu %d failed to shutdown\n", cpu);
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}
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int __ref psci_cpu_kill(unsigned int cpu)
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{
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int err, i;
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if (!psci_ops.affinity_info)
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return 1;
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/*
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* cpu_kill could race with cpu_die and we can
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* potentially end up declaring this cpu undead
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* while it is dying. So, try again a few times.
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*/
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for (i = 0; i < 10; i++) {
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err = psci_ops.affinity_info(cpu_logical_map(cpu), 0);
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if (err == PSCI_0_2_AFFINITY_LEVEL_OFF) {
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pr_info("CPU%d killed.\n", cpu);
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return 1;
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}
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msleep(10);
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pr_info("Retrying again to check for CPU kill\n");
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}
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pr_warn("CPU%d may not have shut down cleanly (AFFINITY_INFO reports %d)\n",
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cpu, err);
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/* Make platform_cpu_kill() fail. */
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return 0;
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}
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#endif
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bool __init psci_smp_available(void)
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{
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/* is cpu_on available at least? */
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return (psci_ops.cpu_on != NULL);
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}
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struct smp_operations __initdata psci_smp_ops = {
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.smp_boot_secondary = psci_boot_secondary,
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#ifdef CONFIG_HOTPLUG_CPU
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.cpu_die = psci_cpu_die,
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.cpu_kill = psci_cpu_kill,
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#endif
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};
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