1/*
2 * Architecture specific (i386) functions for kexec based crash dumps.
3 *
4 * Created by: Hariprasad Nellitheertha (hari@in.ibm.com)
5 *
6 * Copyright (C) IBM Corporation, 2004. All rights reserved.
7 *
8 */
9
10#include <linux/init.h>
11#include <linux/types.h>
12#include <linux/kernel.h>
13#include <linux/smp.h>
14#include <linux/reboot.h>
15#include <linux/kexec.h>
16#include <linux/delay.h>
17#include <linux/elf.h>
18#include <linux/elfcore.h>
19
20#include <asm/processor.h>
21#include <asm/hardirq.h>
22#include <asm/nmi.h>
23#include <asm/hw_irq.h>
24#include <asm/apic.h>
25#include <linux/kdebug.h>
26#include <asm/smp.h>
27
28#include <mach_ipi.h>
29
30
31/* This keeps a track of which one is crashing cpu. */
32static int crashing_cpu;
33
34#if defined(CONFIG_SMP) && defined(CONFIG_X86_LOCAL_APIC)
35static atomic_t waiting_for_crash_ipi;
36
37static int crash_nmi_callback(struct notifier_block *self,
38			unsigned long val, void *data)
39{
40	struct pt_regs *regs;
41	struct pt_regs fixed_regs;
42	int cpu;
43
44	if (val != DIE_NMI_IPI)
45		return NOTIFY_OK;
46
47	regs = ((struct die_args *)data)->regs;
48	cpu = raw_smp_processor_id();
49
50	/* Don't do anything if this handler is invoked on crashing cpu.
51	 * Otherwise, system will completely hang. Crashing cpu can get
52	 * an NMI if system was initially booted with nmi_watchdog parameter.
53	 */
54	if (cpu == crashing_cpu)
55		return NOTIFY_STOP;
56	local_irq_disable();
57
58	if (!user_mode_vm(regs)) {
59		crash_fixup_ss_esp(&fixed_regs, regs);
60		regs = &fixed_regs;
61	}
62	crash_save_cpu(regs, cpu);
63	disable_local_APIC();
64	atomic_dec(&waiting_for_crash_ipi);
65	/* Assume hlt works */
66	halt();
67	for (;;)
68		cpu_relax();
69
70	return 1;
71}
72
73static void smp_send_nmi_allbutself(void)
74{
75	cpumask_t mask = cpu_online_map;
76	cpu_clear(safe_smp_processor_id(), mask);
77	if (!cpus_empty(mask))
78		send_IPI_mask(mask, NMI_VECTOR);
79}
80
81static struct notifier_block crash_nmi_nb = {
82	.notifier_call = crash_nmi_callback,
83};
84
85static void nmi_shootdown_cpus(void)
86{
87	unsigned long msecs;
88
89	atomic_set(&waiting_for_crash_ipi, num_online_cpus() - 1);
90	/* Would it be better to replace the trap vector here? */
91	if (register_die_notifier(&crash_nmi_nb))
92		return;		/* return what? */
93	/* Ensure the new callback function is set before sending
94	 * out the NMI
95	 */
96	wmb();
97
98	smp_send_nmi_allbutself();
99
100	msecs = 1000; /* Wait at most a second for the other cpus to stop */
101	while ((atomic_read(&waiting_for_crash_ipi) > 0) && msecs) {
102		mdelay(1);
103		msecs--;
104	}
105
106	/* Leave the nmi callback set */
107	disable_local_APIC();
108}
109#else
110static void nmi_shootdown_cpus(void)
111{
112	/* There are no cpus to shootdown */
113}
114#endif
115
116void machine_crash_shutdown(struct pt_regs *regs)
117{
118	/* This function is only called after the system
119	 * has panicked or is otherwise in a critical state.
120	 * The minimum amount of code to allow a kexec'd kernel
121	 * to run successfully needs to happen here.
122	 *
123	 * In practice this means shooting down the other cpus in
124	 * an SMP system.
125	 */
126	/* The kernel is broken so disable interrupts */
127	local_irq_disable();
128
129	/* Make a note of crashing cpu. Will be used in NMI callback.*/
130	crashing_cpu = safe_smp_processor_id();
131	nmi_shootdown_cpus();
132	lapic_shutdown();
133#if defined(CONFIG_X86_IO_APIC)
134	disable_IO_APIC();
135#endif
136	crash_save_cpu(regs, safe_smp_processor_id());
137}
138