1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
|
/*
* Architecture specific (x86_64) functions for kexec based crash dumps.
*
* Created by: Hariprasad Nellitheertha (hari@in.ibm.com)
*
* Copyright (C) IBM Corporation, 2004. All rights reserved.
*
*/
#include <linux/init.h>
#include <linux/types.h>
#include <linux/kernel.h>
#include <linux/smp.h>
#include <linux/irq.h>
#include <linux/reboot.h>
#include <linux/kexec.h>
#include <linux/delay.h>
#include <linux/elf.h>
#include <linux/elfcore.h>
#include <asm/processor.h>
#include <asm/hardirq.h>
#include <asm/nmi.h>
#include <asm/hw_irq.h>
#include <asm/mach_apic.h>
#include <asm/kdebug.h>
/* This keeps a track of which one is crashing cpu. */
static int crashing_cpu;
static u32 *append_elf_note(u32 *buf, char *name, unsigned type,
void *data, size_t data_len)
{
struct elf_note note;
note.n_namesz = strlen(name) + 1;
note.n_descsz = data_len;
note.n_type = type;
memcpy(buf, ¬e, sizeof(note));
buf += (sizeof(note) +3)/4;
memcpy(buf, name, note.n_namesz);
buf += (note.n_namesz + 3)/4;
memcpy(buf, data, note.n_descsz);
buf += (note.n_descsz + 3)/4;
return buf;
}
static void final_note(u32 *buf)
{
struct elf_note note;
note.n_namesz = 0;
note.n_descsz = 0;
note.n_type = 0;
memcpy(buf, ¬e, sizeof(note));
}
static void crash_save_this_cpu(struct pt_regs *regs, int cpu)
{
struct elf_prstatus prstatus;
u32 *buf;
if ((cpu < 0) || (cpu >= NR_CPUS))
return;
/* Using ELF notes here is opportunistic.
* I need a well defined structure format
* for the data I pass, and I need tags
* on the data to indicate what information I have
* squirrelled away. ELF notes happen to provide
* all of that that no need to invent something new.
*/
buf = (u32*)per_cpu_ptr(crash_notes, cpu);
if (!buf)
return;
memset(&prstatus, 0, sizeof(prstatus));
prstatus.pr_pid = current->pid;
elf_core_copy_regs(&prstatus.pr_reg, regs);
buf = append_elf_note(buf, "CORE", NT_PRSTATUS, &prstatus,
sizeof(prstatus));
final_note(buf);
}
static void crash_save_self(struct pt_regs *regs)
{
int cpu;
cpu = smp_processor_id();
crash_save_this_cpu(regs, cpu);
}
#ifdef CONFIG_SMP
static atomic_t waiting_for_crash_ipi;
static int crash_nmi_callback(struct notifier_block *self,
unsigned long val, void *data)
{
struct pt_regs *regs;
int cpu;
if (val != DIE_NMI)
return NOTIFY_OK;
regs = ((struct die_args *)data)->regs;
cpu = raw_smp_processor_id();
/*
* Don't do anything if this handler is invoked on crashing cpu.
* Otherwise, system will completely hang. Crashing cpu can get
* an NMI if system was initially booted with nmi_watchdog parameter.
*/
if (cpu == crashing_cpu)
return 1;
local_irq_disable();
crash_save_this_cpu(regs, cpu);
disable_local_APIC();
atomic_dec(&waiting_for_crash_ipi);
/* Assume hlt works */
for(;;)
halt();
return 1;
}
static void smp_send_nmi_allbutself(void)
{
send_IPI_allbutself(NMI_VECTOR);
}
/*
* This code is a best effort heuristic to get the
* other cpus to stop executing. So races with
* cpu hotplug shouldn't matter.
*/
static struct notifier_block crash_nmi_nb = {
.notifier_call = crash_nmi_callback,
};
static void nmi_shootdown_cpus(void)
{
unsigned long msecs;
atomic_set(&waiting_for_crash_ipi, num_online_cpus() - 1);
if (register_die_notifier(&crash_nmi_nb))
return; /* return what? */
/*
* Ensure the new callback function is set before sending
* out the NMI
*/
wmb();
smp_send_nmi_allbutself();
msecs = 1000; /* Wait at most a second for the other cpus to stop */
while ((atomic_read(&waiting_for_crash_ipi) > 0) && msecs) {
mdelay(1);
msecs--;
}
/* Leave the nmi callback set */
disable_local_APIC();
}
#else
static void nmi_shootdown_cpus(void)
{
/* There are no cpus to shootdown */
}
#endif
void machine_crash_shutdown(struct pt_regs *regs)
{
/*
* This function is only called after the system
* has panicked or is otherwise in a critical state.
* The minimum amount of code to allow a kexec'd kernel
* to run successfully needs to happen here.
*
* In practice this means shooting down the other cpus in
* an SMP system.
*/
/* The kernel is broken so disable interrupts */
local_irq_disable();
/* Make a note of crashing cpu. Will be used in NMI callback.*/
crashing_cpu = smp_processor_id();
nmi_shootdown_cpus();
if(cpu_has_apic)
disable_local_APIC();
#if defined(CONFIG_X86_IO_APIC)
disable_IO_APIC();
#endif
crash_save_self(regs);
}
|
