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Viewing changes to arch/sparc/kernel/nmi.c

  • Committer: Package Import Robot
  • Author(s): Alessio Igor Bogani
  • Date: 2011-10-26 11:13:05 UTC
  • Revision ID: package-import@ubuntu.com-20111026111305-tz023xykf0i6eosh
Tags: upstream-3.2.0
Import upstream version 3.2.0

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arch/sparc/kernel/nmi.c
 
1
/* Pseudo NMI support on sparc64 systems.
 
2
 *
 
3
 * Copyright (C) 2009 David S. Miller <davem@davemloft.net>
 
4
 *
 
5
 * The NMI watchdog support and infrastructure is based almost
 
6
 * entirely upon the x86 NMI support code.
 
7
 */
 
8
#include <linux/kernel.h>
 
9
#include <linux/param.h>
 
10
#include <linux/init.h>
 
11
#include <linux/percpu.h>
 
12
#include <linux/nmi.h>
 
13
#include <linux/export.h>
 
14
#include <linux/kprobes.h>
 
15
#include <linux/kernel_stat.h>
 
16
#include <linux/reboot.h>
 
17
#include <linux/slab.h>
 
18
#include <linux/kdebug.h>
 
19
#include <linux/delay.h>
 
20
#include <linux/smp.h>
 
21
 
 
22
#include <asm/perf_event.h>
 
23
#include <asm/ptrace.h>
 
24
#include <asm/pcr.h>
 
25
 
 
26
#include "kstack.h"
 
27
 
 
28
/* We don't have a real NMI on sparc64, but we can fake one
 
29
 * up using profiling counter overflow interrupts and interrupt
 
30
 * levels.
 
31
 *
 
32
 * The profile overflow interrupts at level 15, so we use
 
33
 * level 14 as our IRQ off level.
 
34
 */
 
35
 
 
36
static int panic_on_timeout;
 
37
 
 
38
/* nmi_active:
 
39
 * >0: the NMI watchdog is active, but can be disabled
 
40
 * <0: the NMI watchdog has not been set up, and cannot be enabled
 
41
 *  0: the NMI watchdog is disabled, but can be enabled
 
42
 */
 
43
atomic_t nmi_active = ATOMIC_INIT(0);           /* oprofile uses this */
 
44
EXPORT_SYMBOL(nmi_active);
 
45
 
 
46
static unsigned int nmi_hz = HZ;
 
47
static DEFINE_PER_CPU(short, wd_enabled);
 
48
static int endflag __initdata;
 
49
 
 
50
static DEFINE_PER_CPU(unsigned int, last_irq_sum);
 
51
static DEFINE_PER_CPU(long, alert_counter);
 
52
static DEFINE_PER_CPU(int, nmi_touch);
 
53
 
 
54
void touch_nmi_watchdog(void)
 
55
{
 
56
        if (atomic_read(&nmi_active)) {
 
57
                int cpu;
 
58
 
 
59
                for_each_present_cpu(cpu) {
 
60
                        if (per_cpu(nmi_touch, cpu) != 1)
 
61
                                per_cpu(nmi_touch, cpu) = 1;
 
62
                }
 
63
        }
 
64
 
 
65
        touch_softlockup_watchdog();
 
66
}
 
67
EXPORT_SYMBOL(touch_nmi_watchdog);
 
68
 
 
69
static void die_nmi(const char *str, struct pt_regs *regs, int do_panic)
 
70
{
 
71
        if (notify_die(DIE_NMIWATCHDOG, str, regs, 0,
 
72
                       pt_regs_trap_type(regs), SIGINT) == NOTIFY_STOP)
 
73
                return;
 
74
 
 
75
        console_verbose();
 
76
        bust_spinlocks(1);
 
77
 
 
78
        printk(KERN_EMERG "%s", str);
 
79
        printk(" on CPU%d, ip %08lx, registers:\n",
 
80
               smp_processor_id(), regs->tpc);
 
81
        show_regs(regs);
 
82
        dump_stack();
 
83
 
 
84
        bust_spinlocks(0);
 
85
 
 
86
        if (do_panic || panic_on_oops)
 
87
                panic("Non maskable interrupt");
 
88
 
 
89
        nmi_exit();
 
90
        local_irq_enable();
 
91
        do_exit(SIGBUS);
 
92
}
 
93
 
 
94
notrace __kprobes void perfctr_irq(int irq, struct pt_regs *regs)
 
95
{
 
96
        unsigned int sum, touched = 0;
 
97
        void *orig_sp;
 
98
 
 
99
        clear_softint(1 << irq);
 
100
 
 
101
        local_cpu_data().__nmi_count++;
 
102
 
 
103
        nmi_enter();
 
104
 
 
105
        orig_sp = set_hardirq_stack();
 
106
 
 
107
        if (notify_die(DIE_NMI, "nmi", regs, 0,
 
108
                       pt_regs_trap_type(regs), SIGINT) == NOTIFY_STOP)
 
109
                touched = 1;
 
110
        else
 
111
                pcr_ops->write(PCR_PIC_PRIV);
 
112
 
 
113
        sum = local_cpu_data().irq0_irqs;
 
114
        if (__get_cpu_var(nmi_touch)) {
 
115
                __get_cpu_var(nmi_touch) = 0;
 
116
                touched = 1;
 
117
        }
 
118
        if (!touched && __get_cpu_var(last_irq_sum) == sum) {
 
119
                __this_cpu_inc(alert_counter);
 
120
                if (__this_cpu_read(alert_counter) == 30 * nmi_hz)
 
121
                        die_nmi("BUG: NMI Watchdog detected LOCKUP",
 
122
                                regs, panic_on_timeout);
 
123
        } else {
 
124
                __get_cpu_var(last_irq_sum) = sum;
 
125
                __this_cpu_write(alert_counter, 0);
 
126
        }
 
127
        if (__get_cpu_var(wd_enabled)) {
 
128
                write_pic(picl_value(nmi_hz));
 
129
                pcr_ops->write(pcr_enable);
 
130
        }
 
131
 
 
132
        restore_hardirq_stack(orig_sp);
 
133
 
 
134
        nmi_exit();
 
135
}
 
136
 
 
137
static inline unsigned int get_nmi_count(int cpu)
 
138
{
 
139
        return cpu_data(cpu).__nmi_count;
 
140
}
 
141
 
 
142
static __init void nmi_cpu_busy(void *data)
 
143
{
 
144
        local_irq_enable_in_hardirq();
 
145
        while (endflag == 0)
 
146
                mb();
 
147
}
 
148
 
 
149
static void report_broken_nmi(int cpu, int *prev_nmi_count)
 
150
{
 
151
        printk(KERN_CONT "\n");
 
152
 
 
153
        printk(KERN_WARNING
 
154
                "WARNING: CPU#%d: NMI appears to be stuck (%d->%d)!\n",
 
155
                        cpu, prev_nmi_count[cpu], get_nmi_count(cpu));
 
156
 
 
157
        printk(KERN_WARNING
 
158
                "Please report this to bugzilla.kernel.org,\n");
 
159
        printk(KERN_WARNING
 
160
                "and attach the output of the 'dmesg' command.\n");
 
161
 
 
162
        per_cpu(wd_enabled, cpu) = 0;
 
163
        atomic_dec(&nmi_active);
 
164
}
 
165
 
 
166
void stop_nmi_watchdog(void *unused)
 
167
{
 
168
        pcr_ops->write(PCR_PIC_PRIV);
 
169
        __get_cpu_var(wd_enabled) = 0;
 
170
        atomic_dec(&nmi_active);
 
171
}
 
172
 
 
173
static int __init check_nmi_watchdog(void)
 
174
{
 
175
        unsigned int *prev_nmi_count;
 
176
        int cpu, err;
 
177
 
 
178
        if (!atomic_read(&nmi_active))
 
179
                return 0;
 
180
 
 
181
        prev_nmi_count = kmalloc(nr_cpu_ids * sizeof(unsigned int), GFP_KERNEL);
 
182
        if (!prev_nmi_count) {
 
183
                err = -ENOMEM;
 
184
                goto error;
 
185
        }
 
186
 
 
187
        printk(KERN_INFO "Testing NMI watchdog ... ");
 
188
 
 
189
        smp_call_function(nmi_cpu_busy, (void *)&endflag, 0);
 
190
 
 
191
        for_each_possible_cpu(cpu)
 
192
                prev_nmi_count[cpu] = get_nmi_count(cpu);
 
193
        local_irq_enable();
 
194
        mdelay((20 * 1000) / nmi_hz); /* wait 20 ticks */
 
195
 
 
196
        for_each_online_cpu(cpu) {
 
197
                if (!per_cpu(wd_enabled, cpu))
 
198
                        continue;
 
199
                if (get_nmi_count(cpu) - prev_nmi_count[cpu] <= 5)
 
200
                        report_broken_nmi(cpu, prev_nmi_count);
 
201
        }
 
202
        endflag = 1;
 
203
        if (!atomic_read(&nmi_active)) {
 
204
                kfree(prev_nmi_count);
 
205
                atomic_set(&nmi_active, -1);
 
206
                err = -ENODEV;
 
207
                goto error;
 
208
        }
 
209
        printk("OK.\n");
 
210
 
 
211
        nmi_hz = 1;
 
212
 
 
213
        kfree(prev_nmi_count);
 
214
        return 0;
 
215
error:
 
216
        on_each_cpu(stop_nmi_watchdog, NULL, 1);
 
217
        return err;
 
218
}
 
219
 
 
220
void start_nmi_watchdog(void *unused)
 
221
{
 
222
        __get_cpu_var(wd_enabled) = 1;
 
223
        atomic_inc(&nmi_active);
 
224
 
 
225
        pcr_ops->write(PCR_PIC_PRIV);
 
226
        write_pic(picl_value(nmi_hz));
 
227
 
 
228
        pcr_ops->write(pcr_enable);
 
229
}
 
230
 
 
231
static void nmi_adjust_hz_one(void *unused)
 
232
{
 
233
        if (!__get_cpu_var(wd_enabled))
 
234
                return;
 
235
 
 
236
        pcr_ops->write(PCR_PIC_PRIV);
 
237
        write_pic(picl_value(nmi_hz));
 
238
 
 
239
        pcr_ops->write(pcr_enable);
 
240
}
 
241
 
 
242
void nmi_adjust_hz(unsigned int new_hz)
 
243
{
 
244
        nmi_hz = new_hz;
 
245
        on_each_cpu(nmi_adjust_hz_one, NULL, 1);
 
246
}
 
247
EXPORT_SYMBOL_GPL(nmi_adjust_hz);
 
248
 
 
249
static int nmi_shutdown(struct notifier_block *nb, unsigned long cmd, void *p)
 
250
{
 
251
        on_each_cpu(stop_nmi_watchdog, NULL, 1);
 
252
        return 0;
 
253
}
 
254
 
 
255
static struct notifier_block nmi_reboot_notifier = {
 
256
        .notifier_call = nmi_shutdown,
 
257
};
 
258
 
 
259
int __init nmi_init(void)
 
260
{
 
261
        int err;
 
262
 
 
263
        on_each_cpu(start_nmi_watchdog, NULL, 1);
 
264
 
 
265
        err = check_nmi_watchdog();
 
266
        if (!err) {
 
267
                err = register_reboot_notifier(&nmi_reboot_notifier);
 
268
                if (err) {
 
269
                        on_each_cpu(stop_nmi_watchdog, NULL, 1);
 
270
                        atomic_set(&nmi_active, -1);
 
271
                }
 
272
        }
 
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 0;
 
283
}
 
284
__setup("nmi_watchdog=", setup_nmi_watchdog);