arch/sparc/kernel/nmi.c

   1 // SPDX-License-Identifier: GPL-2.0-only
   2 /* Pseudo NMI support on sparc64 systems.
   3  *
   4  * Copyright (C) 2009 David S. Miller <davem@davemloft.net>
   5  *
   6  * The NMI watchdog support and infrastructure is based almost
   7  * entirely upon the x86 NMI support code.
   8  */
   9 #include <linux/kernel.h>
  10 #include <linux/param.h>
  11 #include <linux/init.h>
  12 #include <linux/percpu.h>
  13 #include <linux/nmi.h>
  14 #include <linux/export.h>
  15 #include <linux/kprobes.h>
  16 #include <linux/kernel_stat.h>
  17 #include <linux/reboot.h>
  18 #include <linux/slab.h>
  19 #include <linux/kdebug.h>
  20 #include <linux/delay.h>
  21 #include <linux/smp.h>
  22
  23 #include <asm/perf_event.h>
  24 #include <asm/ptrace.h>
  25 #include <asm/pcr.h>
  26
  27 #include "kstack.h"
  28
  29 /* We don't have a real NMI on sparc64, but we can fake one
  30  * up using profiling counter overflow interrupts and interrupt
  31  * levels.
  32  *
  33  * The profile overflow interrupts at level 15, so we use
  34  * level 14 as our IRQ off level.
  35  */
  36
  37 static int panic_on_timeout;
  38
  39 /* nmi_active:
  40  * >0: the NMI watchdog is active, but can be disabled
  41  * <0: the NMI watchdog has not been set up, and cannot be enabled
  42  *  0: the NMI watchdog is disabled, but can be enabled
  43  */
  44 atomic_t nmi_active = ATOMIC_INIT(0);           /* oprofile uses this */
  45 EXPORT_SYMBOL(nmi_active);
  46 static int nmi_init_done;
  47 static unsigned int nmi_hz = HZ;
  48 static DEFINE_PER_CPU(short, wd_enabled);
  49 static int endflag __initdata;
  50
  51 static DEFINE_PER_CPU(unsigned int, last_irq_sum);
  52 static DEFINE_PER_CPU(long, alert_counter);
  53 static DEFINE_PER_CPU(int, nmi_touch);
  54
  55 void arch_touch_nmi_watchdog(void)
  56 {
  57         if (atomic_read(&nmi_active)) {
  58                 int cpu;
  59
  60                 for_each_present_cpu(cpu) {
  61                         if (per_cpu(nmi_touch, cpu) != 1)
  62                                 per_cpu(nmi_touch, cpu) = 1;
  63                 }
  64         }
  65 }
  66 EXPORT_SYMBOL(arch_touch_nmi_watchdog);
  67
  68 int __init watchdog_hardlockup_probe(void)
  69 {
  70         return 0;
  71 }
  72
  73 static void die_nmi(const char *str, struct pt_regs *regs, int do_panic)
  74 {
  75         int this_cpu = smp_processor_id();
  76
  77         if (notify_die(DIE_NMIWATCHDOG, str, regs, 0,
  78                        pt_regs_trap_type(regs), SIGINT) == NOTIFY_STOP)
  79                 return;
  80
  81         if (do_panic || panic_on_oops)
  82                 panic("Watchdog detected hard LOCKUP on cpu %d", this_cpu);
  83         else
  84                 WARN(1, "Watchdog detected hard LOCKUP on cpu %d", this_cpu);
  85 }
  86
  87 notrace __kprobes void perfctr_irq(int irq, struct pt_regs *regs)
  88 {
  89         unsigned int sum, touched = 0;
  90         void *orig_sp;
  91
  92         clear_softint(1 << irq);
  93
  94         local_cpu_data().__nmi_count++;
  95
  96         nmi_enter();
  97
  98         orig_sp = set_hardirq_stack();
  99
 100         if (notify_die(DIE_NMI, "nmi", regs, 0,
 101                        pt_regs_trap_type(regs), SIGINT) == NOTIFY_STOP)
 102                 touched = 1;
 103         else
 104                 pcr_ops->write_pcr(0, pcr_ops->pcr_nmi_disable);
 105
 106         sum = local_cpu_data().irq0_irqs;
 107         if (__this_cpu_read(nmi_touch)) {
 108                 __this_cpu_write(nmi_touch, 0);
 109                 touched = 1;
 110         }
 111         if (!touched && __this_cpu_read(last_irq_sum) == sum) {
 112                 __this_cpu_inc(alert_counter);
 113                 if (__this_cpu_read(alert_counter) == 30 * nmi_hz)
 114                         die_nmi("BUG: NMI Watchdog detected LOCKUP",
 115                                 regs, panic_on_timeout);
 116         } else {
 117                 __this_cpu_write(last_irq_sum, sum);
 118                 __this_cpu_write(alert_counter, 0);
 119         }
 120         if (__this_cpu_read(wd_enabled)) {
 121                 pcr_ops->write_pic(0, pcr_ops->nmi_picl_value(nmi_hz));
 122                 pcr_ops->write_pcr(0, pcr_ops->pcr_nmi_enable);
 123         }
 124
 125         restore_hardirq_stack(orig_sp);
 126
 127         nmi_exit();
 128 }
 129
 130 static inline unsigned int get_nmi_count(int cpu)
 131 {
 132         return cpu_data(cpu).__nmi_count;
 133 }
 134
 135 static __init void nmi_cpu_busy(void *data)
 136 {
 137         while (endflag == 0)
 138                 mb();
 139 }
 140
 141 static void report_broken_nmi(int cpu, int *prev_nmi_count)
 142 {
 143         printk(KERN_CONT "\n");
 144
 145         printk(KERN_WARNING
 146                 "WARNING: CPU#%d: NMI appears to be stuck (%d->%d)!\n",
 147                         cpu, prev_nmi_count[cpu], get_nmi_count(cpu));
 148
 149         printk(KERN_WARNING
 150                 "Please report this to bugzilla.kernel.org,\n");
 151         printk(KERN_WARNING
 152                 "and attach the output of the 'dmesg' command.\n");
 153
 154         per_cpu(wd_enabled, cpu) = 0;
 155         atomic_dec(&nmi_active);
 156 }
 157
 158 void stop_nmi_watchdog(void *unused)
 159 {
 160         if (!__this_cpu_read(wd_enabled))
 161                 return;
 162         pcr_ops->write_pcr(0, pcr_ops->pcr_nmi_disable);
 163         __this_cpu_write(wd_enabled, 0);
 164         atomic_dec(&nmi_active);
 165 }
 166
 167 static int __init check_nmi_watchdog(void)
 168 {
 169         unsigned int *prev_nmi_count;
 170         int cpu, err;
 171
 172         if (!atomic_read(&nmi_active))
 173                 return 0;
 174
 175         prev_nmi_count = kmalloc_array(nr_cpu_ids, sizeof(unsigned int),
 176                                        GFP_KERNEL);
 177         if (!prev_nmi_count) {
 178                 err = -ENOMEM;
 179                 goto error;
 180         }
 181
 182         printk(KERN_INFO "Testing NMI watchdog ... ");
 183
 184         smp_call_function(nmi_cpu_busy, (void *)&endflag, 0);
 185
 186         for_each_possible_cpu(cpu)
 187                 prev_nmi_count[cpu] = get_nmi_count(cpu);
 188         local_irq_enable();
 189         mdelay((20 * 1000) / nmi_hz); /* wait 20 ticks */
 190
 191         for_each_online_cpu(cpu) {
 192                 if (!per_cpu(wd_enabled, cpu))
 193                         continue;
 194                 if (get_nmi_count(cpu) - prev_nmi_count[cpu] <= 5)
 195                         report_broken_nmi(cpu, prev_nmi_count);
 196         }
 197         endflag = 1;
 198         if (!atomic_read(&nmi_active)) {
 199                 kfree(prev_nmi_count);
 200                 atomic_set(&nmi_active, -1);
 201                 err = -ENODEV;
 202                 goto error;
 203         }
 204         printk("OK.\n");
 205
 206         nmi_hz = 1;
 207
 208         kfree(prev_nmi_count);
 209         return 0;
 210 error:
 211         on_each_cpu(stop_nmi_watchdog, NULL, 1);
 212         return err;
 213 }
 214
 215 void start_nmi_watchdog(void *unused)
 216 {
 217         if (__this_cpu_read(wd_enabled))
 218                 return;
 219
 220         __this_cpu_write(wd_enabled, 1);
 221         atomic_inc(&nmi_active);
 222
 223         pcr_ops->write_pcr(0, pcr_ops->pcr_nmi_disable);
 224         pcr_ops->write_pic(0, pcr_ops->nmi_picl_value(nmi_hz));
 225
 226         pcr_ops->write_pcr(0, pcr_ops->pcr_nmi_enable);
 227 }
 228
 229 static void nmi_adjust_hz_one(void *unused)
 230 {
 231         if (!__this_cpu_read(wd_enabled))
 232                 return;
 233
 234         pcr_ops->write_pcr(0, pcr_ops->pcr_nmi_disable);
 235         pcr_ops->write_pic(0, pcr_ops->nmi_picl_value(nmi_hz));
 236
 237         pcr_ops->write_pcr(0, pcr_ops->pcr_nmi_enable);
 238 }
 239
 240 void nmi_adjust_hz(unsigned int new_hz)
 241 {
 242         nmi_hz = new_hz;
 243         on_each_cpu(nmi_adjust_hz_one, NULL, 1);
 244 }
 245 EXPORT_SYMBOL_GPL(nmi_adjust_hz);
 246
 247 static int nmi_shutdown(struct notifier_block *nb, unsigned long cmd, void *p)
 248 {
 249         on_each_cpu(stop_nmi_watchdog, NULL, 1);
 250         return 0;
 251 }
 252
 253 static struct notifier_block nmi_reboot_notifier = {
 254         .notifier_call = nmi_shutdown,
 255 };
 256
 257 int __init nmi_init(void)
 258 {
 259         int err;
 260
 261         on_each_cpu(start_nmi_watchdog, NULL, 1);
 262
 263         err = check_nmi_watchdog();
 264         if (!err) {
 265                 err = register_reboot_notifier(&nmi_reboot_notifier);
 266                 if (err) {
 267                         on_each_cpu(stop_nmi_watchdog, NULL, 1);
 268                         atomic_set(&nmi_active, -1);
 269                 }
 270         }
 271
 272         nmi_init_done = 1;
 273
 274         return err;
 275 }
 276
 277 static int __init setup_nmi_watchdog(char *str)
 278 {
 279         if (!strncmp(str, "panic", 5))
 280                 panic_on_timeout = 1;
 281
 282         return 1;
 283 }
 284 __setup("nmi_watchdog=", setup_nmi_watchdog);
 285
 286 /*
 287  * sparc specific NMI watchdog enable function.
 288  * Enables watchdog if it is not enabled already.
 289  */
 290 void watchdog_hardlockup_enable(unsigned int cpu)
 291 {
 292         if (atomic_read(&nmi_active) == -1) {
 293                 pr_warn("NMI watchdog cannot be enabled or disabled\n");
 294                 return;
 295         }
 296
 297         /*
 298          * watchdog thread could start even before nmi_init is called.
 299          * Just Return in that case. Let nmi_init finish the init
 300          * process first.
 301          */
 302         if (!nmi_init_done)
 303                 return;
 304
 305         smp_call_function_single(cpu, start_nmi_watchdog, NULL, 1);
 306 }
 307 /*
 308  * sparc specific NMI watchdog disable function.
 309  * Disables watchdog if it is not disabled already.
 310  */
 311 void watchdog_hardlockup_disable(unsigned int cpu)
 312 {
 313         if (atomic_read(&nmi_active) == -1)
 314                 pr_warn_once("NMI watchdog cannot be enabled or disabled\n");
 315         else
 316                 smp_call_function_single(cpu, stop_nmi_watchdog, NULL, 1);
 317 }