1 files changed, 317 insertions, 0 deletions
diff --git a/arch/sparc/kernel/nmi.c b/arch/sparc/kernel/nmi.c
new file mode 100644
index 000000000..17cdfdbf1
--- /dev/null
+++ b/arch/sparc/kernel/nmi.c
@@ -0,0 +1,317 @@
+// 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 0;
+}
+__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);
+}