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authorDavid S. Miller <davem@davemloft.net>2009-01-30 08:22:47 +0300
committerDavid S. Miller <davem@davemloft.net>2009-01-30 11:03:53 +0300
commite5553a6d04421eec326a629571d696e8e745a0e4 (patch)
treeb6fe49a18135dbe27a464fb78828b2150c679689 /arch/sparc/kernel/nmi.c
parentc3cf5e8cc56d272f828a66610bb78bbb727b2ce1 (diff)
downloadlinux-e5553a6d04421eec326a629571d696e8e745a0e4.tar.xz
sparc64: Implement NMI watchdog on capable cpus.
Signed-off-by: David S. Miller <davem@davemloft.net>
Diffstat (limited to 'arch/sparc/kernel/nmi.c')
-rw-r--r--arch/sparc/kernel/nmi.c224
1 files changed, 224 insertions, 0 deletions
diff --git a/arch/sparc/kernel/nmi.c b/arch/sparc/kernel/nmi.c
new file mode 100644
index 000000000000..ffc690093343
--- /dev/null
+++ b/arch/sparc/kernel/nmi.c
@@ -0,0 +1,224 @@
+/* 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/module.h>
+#include <linux/kprobes.h>
+#include <linux/kernel_stat.h>
+#include <linux/slab.h>
+#include <linux/kdebug.h>
+#include <linux/delay.h>
+#include <linux/smp.h>
+
+#include <asm/ptrace.h>
+#include <asm/local.h>
+#include <asm/pcr.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 nmi_watchdog_active;
+static int panic_on_timeout;
+
+int nmi_usable;
+EXPORT_SYMBOL_GPL(nmi_usable);
+
+static unsigned int nmi_hz = HZ;
+
+static DEFINE_PER_CPU(unsigned int, last_irq_sum);
+static DEFINE_PER_CPU(local_t, alert_counter);
+static DEFINE_PER_CPU(int, nmi_touch);
+
+void touch_nmi_watchdog(void)
+{
+ if (nmi_watchdog_active) {
+ int cpu;
+
+ for_each_present_cpu(cpu) {
+ if (per_cpu(nmi_touch, cpu) != 1)
+ per_cpu(nmi_touch, cpu) = 1;
+ }
+ }
+
+ touch_softlockup_watchdog();
+}
+EXPORT_SYMBOL(touch_nmi_watchdog);
+
+static void die_nmi(const char *str, struct pt_regs *regs, int do_panic)
+{
+ if (notify_die(DIE_NMIWATCHDOG, str, regs, 0,
+ pt_regs_trap_type(regs), SIGINT) == NOTIFY_STOP)
+ return;
+
+ console_verbose();
+ bust_spinlocks(1);
+
+ printk(KERN_EMERG "%s", str);
+ printk(" on CPU%d, ip %08lx, registers:\n",
+ smp_processor_id(), regs->tpc);
+ show_regs(regs);
+
+ bust_spinlocks(0);
+
+ if (do_panic || panic_on_oops)
+ panic("Non maskable interrupt");
+
+ local_irq_enable();
+ do_exit(SIGBUS);
+}
+
+notrace __kprobes void perfctr_irq(int irq, struct pt_regs *regs)
+{
+ unsigned int sum, touched = 0;
+ int cpu = smp_processor_id();
+
+ clear_softint(1 << irq);
+ pcr_ops->write(PCR_PIC_PRIV);
+
+ local_cpu_data().__nmi_count++;
+
+ if (notify_die(DIE_NMI, "nmi", regs, 0,
+ pt_regs_trap_type(regs), SIGINT) == NOTIFY_STOP)
+ touched = 1;
+
+ sum = kstat_cpu(cpu).irqs[0];
+ if (__get_cpu_var(nmi_touch)) {
+ __get_cpu_var(nmi_touch) = 0;
+ touched = 1;
+ }
+ if (!touched && __get_cpu_var(last_irq_sum) == sum) {
+ local_inc(&__get_cpu_var(alert_counter));
+ if (local_read(&__get_cpu_var(alert_counter)) == 5 * nmi_hz)
+ die_nmi("BUG: NMI Watchdog detected LOCKUP",
+ regs, panic_on_timeout);
+ } else {
+ __get_cpu_var(last_irq_sum) = sum;
+ local_set(&__get_cpu_var(alert_counter), 0);
+ }
+ if (nmi_usable) {
+ write_pic(picl_value(nmi_hz));
+ pcr_ops->write(pcr_enable);
+ }
+}
+
+static inline unsigned int get_nmi_count(int cpu)
+{
+ return cpu_data(cpu).__nmi_count;
+}
+
+static int endflag __initdata;
+
+static __init void nmi_cpu_busy(void *data)
+{
+ local_irq_enable_in_hardirq();
+ 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");
+
+ nmi_usable = 0;
+}
+
+static void stop_watchdog(void *unused)
+{
+ pcr_ops->write(PCR_PIC_PRIV);
+}
+
+static int __init check_nmi_watchdog(void)
+{
+ unsigned int *prev_nmi_count;
+ int cpu, err;
+
+ prev_nmi_count = kmalloc(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 (get_nmi_count(cpu) - prev_nmi_count[cpu] <= 5)
+ report_broken_nmi(cpu, prev_nmi_count);
+ }
+ endflag = 1;
+ if (!nmi_usable) {
+ kfree(prev_nmi_count);
+ err = -ENODEV;
+ goto error;
+ }
+ printk("OK.\n");
+
+ nmi_hz = 1;
+
+ kfree(prev_nmi_count);
+ return 0;
+error:
+ on_each_cpu(stop_watchdog, NULL, 1);
+ return err;
+}
+
+static void start_watchdog(void *unused)
+{
+ pcr_ops->write(PCR_PIC_PRIV);
+ write_pic(picl_value(nmi_hz));
+
+ pcr_ops->write(pcr_enable);
+}
+
+void nmi_adjust_hz(unsigned int new_hz)
+{
+ nmi_hz = new_hz;
+ on_each_cpu(start_watchdog, NULL, 1);
+}
+EXPORT_SYMBOL_GPL(nmi_adjust_hz);
+
+int __init nmi_init(void)
+{
+ nmi_usable = 1;
+
+ on_each_cpu(start_watchdog, NULL, 1);
+
+ return check_nmi_watchdog();
+}
+
+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);