// SPDX-License-Identifier: GPL-2.0-only /* Pseudo NMI support on sparc64 systems. * * Copyright (C) 2009 David S. Miller <davem@davemloft.net> * * The NMI watchdog support and infrastructure is based almost * entirely upon the x86 NMI support code. */ #include <linux/kernel.h> #include <linux/param.h> #include <linux/init.h> #include <linux/percpu.h> #include <linux/nmi.h> #include <linux/export.h> #include <linux/kprobes.h> #include <linux/kernel_stat.h> #include <linux/reboot.h> #include <linux/slab.h> #include <linux/kdebug.h> #include <linux/delay.h> #include <linux/smp.h> #include <asm/perf_event.h> #include <asm/ptrace.h> #include <asm/pcr.h> #include "kstack.h" /* We don't have a real NMI on sparc64, but we can fake one * up using profiling counter overflow interrupts and interrupt * levels. * * The profile overflow interrupts at level 15, so we use * level 14 as our IRQ off level. */ static int panic_on_timeout; /* nmi_active: * >0: the NMI watchdog is active, but can be disabled * <0: the NMI watchdog has not been set up, and cannot be enabled * 0: the NMI watchdog is disabled, but can be enabled */ atomic_t nmi_active = ATOMIC_INIT(0); /* oprofile uses this */ EXPORT_SYMBOL(nmi_active); static int nmi_init_done; static unsigned int nmi_hz = HZ; static DEFINE_PER_CPU(short, wd_enabled); static int endflag __initdata; static DEFINE_PER_CPU(unsigned int, last_irq_sum); static DEFINE_PER_CPU(long, alert_counter); static DEFINE_PER_CPU(int, nmi_touch); void arch_touch_nmi_watchdog(void) { if (atomic_read(&nmi_active)) { int cpu; for_each_present_cpu(cpu) { if (per_cpu(nmi_touch, cpu) != 1) per_cpu(nmi_touch, cpu) = 1; } } } EXPORT_SYMBOL(arch_touch_nmi_watchdog); int __init watchdog_hardlockup_probe(void) { return 0; } static void die_nmi(const char *str, struct pt_regs *regs, int do_panic) { int this_cpu = smp_processor_id(); if (notify_die(DIE_NMIWATCHDOG, str, regs, 0, pt_regs_trap_type(regs), SIGINT) == NOTIFY_STOP) return; if (do_panic || panic_on_oops) panic("Watchdog detected hard LOCKUP on cpu %d", this_cpu); else WARN(1, "Watchdog detected hard LOCKUP on cpu %d", this_cpu); } notrace __kprobes void perfctr_irq(int irq, struct pt_regs *regs) { unsigned int sum, touched = 0; void *orig_sp; clear_softint(1 << irq); local_cpu_data().__nmi_count++; nmi_enter(); orig_sp = set_hardirq_stack(); if (notify_die(DIE_NMI, "nmi", regs, 0, pt_regs_trap_type(regs), SIGINT) == NOTIFY_STOP) touched = 1; else pcr_ops->write_pcr(0, pcr_ops->pcr_nmi_disable); sum = local_cpu_data().irq0_irqs; if (__this_cpu_read(nmi_touch)) { __this_cpu_write(nmi_touch, 0); touched = 1; } if (!touched && __this_cpu_read(last_irq_sum) == sum) { __this_cpu_inc(alert_counter); if (__this_cpu_read(alert_counter) == 30 * nmi_hz) die_nmi("BUG: NMI Watchdog detected LOCKUP", regs, panic_on_timeout); } else { __this_cpu_write(last_irq_sum, sum); __this_cpu_write(alert_counter, 0); } if (__this_cpu_read(wd_enabled)) { pcr_ops->write_pic(0, pcr_ops->nmi_picl_value(nmi_hz)); pcr_ops->write_pcr(0, pcr_ops->pcr_nmi_enable); } restore_hardirq_stack(orig_sp); nmi_exit(); } static inline unsigned int get_nmi_count(int cpu) { return cpu_data(cpu).__nmi_count; } static __init void nmi_cpu_busy(void *data) { while (endflag == 0) mb(); } static void report_broken_nmi(int cpu, int *prev_nmi_count) { printk(KERN_CONT "\n"); printk(KERN_WARNING "WARNING: CPU#%d: NMI appears to be stuck (%d->%d)!\n", cpu, prev_nmi_count[cpu], get_nmi_count(cpu)); printk(KERN_WARNING "Please report this to bugzilla.kernel.org,\n"); printk(KERN_WARNING "and attach the output of the 'dmesg' command.\n"); per_cpu(wd_enabled, cpu) = 0; atomic_dec(&nmi_active); } void stop_nmi_watchdog(void *unused) { if (!__this_cpu_read(wd_enabled)) return; pcr_ops->write_pcr(0, pcr_ops->pcr_nmi_disable); __this_cpu_write(wd_enabled, 0); atomic_dec(&nmi_active); } static int __init check_nmi_watchdog(void) { unsigned int *prev_nmi_count; int cpu, err; if (!atomic_read(&nmi_active)) return 0; prev_nmi_count = kmalloc_array(nr_cpu_ids, sizeof(unsigned int), GFP_KERNEL); if (!prev_nmi_count) { err = -ENOMEM; goto error; } printk(KERN_INFO "Testing NMI watchdog ... "); smp_call_function(nmi_cpu_busy, (void *)&endflag, 0); for_each_possible_cpu(cpu) prev_nmi_count[cpu] = get_nmi_count(cpu); local_irq_enable(); mdelay((20 * 1000) / nmi_hz); /* wait 20 ticks */ for_each_online_cpu(cpu) { if (!per_cpu(wd_enabled, cpu)) continue; if (get_nmi_count(cpu) - prev_nmi_count[cpu] <= 5) report_broken_nmi(cpu, prev_nmi_count); } endflag = 1; if (!atomic_read(&nmi_active)) { kfree(prev_nmi_count); atomic_set(&nmi_active, -1); err = -ENODEV; goto error; } printk("OK.\n"); nmi_hz = 1; kfree(prev_nmi_count); return 0; error: on_each_cpu(stop_nmi_watchdog, NULL, 1); return err; } void start_nmi_watchdog(void *unused) { if (__this_cpu_read(wd_enabled)) return; __this_cpu_write(wd_enabled, 1); atomic_inc(&nmi_active); pcr_ops->write_pcr(0, pcr_ops->pcr_nmi_disable); pcr_ops->write_pic(0, pcr_ops->nmi_picl_value(nmi_hz)); pcr_ops->write_pcr(0, pcr_ops->pcr_nmi_enable); } static void nmi_adjust_hz_one(void *unused) { if (!__this_cpu_read(wd_enabled)) return; pcr_ops->write_pcr(0, pcr_ops->pcr_nmi_disable); pcr_ops->write_pic(0, pcr_ops->nmi_picl_value(nmi_hz)); pcr_ops->write_pcr(0, pcr_ops->pcr_nmi_enable); } void nmi_adjust_hz(unsigned int new_hz) { nmi_hz = new_hz; on_each_cpu(nmi_adjust_hz_one, NULL, 1); } EXPORT_SYMBOL_GPL(nmi_adjust_hz); static int nmi_shutdown(struct notifier_block *nb, unsigned long cmd, void *p) { on_each_cpu(stop_nmi_watchdog, NULL, 1); return 0; } static struct notifier_block nmi_reboot_notifier = { .notifier_call = nmi_shutdown, }; int __init nmi_init(void) { int err; on_each_cpu(start_nmi_watchdog, NULL, 1); err = check_nmi_watchdog(); if (!err) { err = register_reboot_notifier(&nmi_reboot_notifier); if (err) { on_each_cpu(stop_nmi_watchdog, NULL, 1); atomic_set(&nmi_active, -1); } } nmi_init_done = 1; return err; } static int __init setup_nmi_watchdog(char *str) { if (!strncmp(str, "panic", 5)) panic_on_timeout = 1; return 1; } __setup("nmi_watchdog=", setup_nmi_watchdog); /* * sparc specific NMI watchdog enable function. * Enables watchdog if it is not enabled already. */ void watchdog_hardlockup_enable(unsigned int cpu) { if (atomic_read(&nmi_active) == -1) { pr_warn("NMI watchdog cannot be enabled or disabled\n"); return; } /* * watchdog thread could start even before nmi_init is called. * Just Return in that case. Let nmi_init finish the init * process first. */ if (!nmi_init_done) return; smp_call_function_single(cpu, start_nmi_watchdog, NULL, 1); } /* * sparc specific NMI watchdog disable function. * Disables watchdog if it is not disabled already. */ void watchdog_hardlockup_disable(unsigned int cpu) { if (atomic_read(&nmi_active) == -1) pr_warn_once("NMI watchdog cannot be enabled or disabled\n"); else smp_call_function_single(cpu, stop_nmi_watchdog, NULL, 1); }