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1/*
2 * Architecture specific (PPC64) functions for kexec based crash dumps.
3 *
4 * Copyright (C) 2005, IBM Corp.
5 *
6 * Created by: Haren Myneni
7 *
8 * This source code is licensed under the GNU General Public License,
9 * Version 2. See the file COPYING for more details.
10 *
11 */
12
13#undef DEBUG
14
15#include <linux/kernel.h>
16#include <linux/smp.h>
17#include <linux/reboot.h>
18#include <linux/kexec.h>
19#include <linux/bootmem.h>
20#include <linux/crash_dump.h>
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21#include <linux/delay.h>
22#include <linux/elf.h>
23#include <linux/elfcore.h>
24#include <linux/init.h>
d6c1a908 25#include <linux/irq.h>
cc532915 26#include <linux/types.h>
c0ce7d08 27#include <linux/irq.h>
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28
29#include <asm/processor.h>
30#include <asm/machdep.h>
c0ce7d08 31#include <asm/kexec.h>
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32#include <asm/kdump.h>
33#include <asm/lmb.h>
34#include <asm/firmware.h>
f6cc82fc 35#include <asm/smp.h>
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36
37#ifdef DEBUG
38#include <asm/udbg.h>
39#define DBG(fmt...) udbg_printf(fmt)
40#else
41#define DBG(fmt...)
42#endif
43
44/* This keeps a track of which one is crashing cpu. */
45int crashing_cpu = -1;
c0ce7d08 46static cpumask_t cpus_in_crash = CPU_MASK_NONE;
b6f35b49 47cpumask_t cpus_in_sr = CPU_MASK_NONE;
cc532915 48
cc532915 49#ifdef CONFIG_SMP
c0ce7d08 50static atomic_t enter_on_soft_reset = ATOMIC_INIT(0);
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51
52void crash_ipi_callback(struct pt_regs *regs)
53{
54 int cpu = smp_processor_id();
55
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56 if (!cpu_online(cpu))
57 return;
58
d04c56f7 59 hard_irq_disable();
c0ce7d08 60 if (!cpu_isset(cpu, cpus_in_crash))
85916f81 61 crash_save_cpu(regs, cpu);
c0ce7d08 62 cpu_set(cpu, cpus_in_crash);
cc532915 63
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64 /*
65 * Entered via soft-reset - could be the kdump
66 * process is invoked using soft-reset or user activated
67 * it if some CPU did not respond to an IPI.
68 * For soft-reset, the secondary CPU can enter this func
69 * twice. 1 - using IPI, and 2. soft-reset.
70 * Tell the kexec CPU that entered via soft-reset and ready
71 * to go down.
72 */
73 if (cpu_isset(cpu, cpus_in_sr)) {
74 cpu_clear(cpu, cpus_in_sr);
75 atomic_inc(&enter_on_soft_reset);
76 }
77
78 /*
79 * Starting the kdump boot.
80 * This barrier is needed to make sure that all CPUs are stopped.
81 * If not, soft-reset will be invoked to bring other CPUs.
82 */
83 while (!cpu_isset(crashing_cpu, cpus_in_crash))
84 cpu_relax();
85
86 if (ppc_md.kexec_cpu_down)
87 ppc_md.kexec_cpu_down(1, 1);
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88
89#ifdef CONFIG_PPC64
cc532915 90 kexec_smp_wait();
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91#else
92 for (;;); /* FIXME */
93#endif
94
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95 /* NOTREACHED */
96}
97
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98/*
99 * Wait until all CPUs are entered via soft-reset.
100 */
101static void crash_soft_reset_check(int cpu)
102{
103 unsigned int ncpus = num_online_cpus() - 1;/* Excluding the panic cpu */
104
105 cpu_clear(cpu, cpus_in_sr);
106 while (atomic_read(&enter_on_soft_reset) != ncpus)
107 cpu_relax();
108}
109
110
111static void crash_kexec_prepare_cpus(int cpu)
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112{
113 unsigned int msecs;
114
c0ce7d08 115 unsigned int ncpus = num_online_cpus() - 1;/* Excluding the panic cpu */
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116
117 crash_send_ipi(crash_ipi_callback);
118 smp_wmb();
119
120 /*
121 * FIXME: Until we will have the way to stop other CPUSs reliabally,
122 * the crash CPU will send an IPI and wait for other CPUs to
c0ce7d08 123 * respond.
01aaed9d 124 * Delay of at least 10 seconds.
cc532915 125 */
c0ce7d08 126 printk(KERN_EMERG "Sending IPI to other cpus...\n");
01aaed9d 127 msecs = 10000;
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128 while ((cpus_weight(cpus_in_crash) < ncpus) && (--msecs > 0)) {
129 cpu_relax();
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130 mdelay(1);
131 }
132
133 /* Would it be better to replace the trap vector here? */
134
135 /*
136 * FIXME: In case if we do not get all CPUs, one possibility: ask the
137 * user to do soft reset such that we get all.
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138 * Soft-reset will be used until better mechanism is implemented.
139 */
140 if (cpus_weight(cpus_in_crash) < ncpus) {
141 printk(KERN_EMERG "done waiting: %d cpu(s) not responding\n",
142 ncpus - cpus_weight(cpus_in_crash));
143 printk(KERN_EMERG "Activate soft-reset to stop other cpu(s)\n");
144 cpus_in_sr = CPU_MASK_NONE;
145 atomic_set(&enter_on_soft_reset, 0);
146 while (cpus_weight(cpus_in_crash) < ncpus)
147 cpu_relax();
148 }
149 /*
150 * Make sure all CPUs are entered via soft-reset if the kdump is
151 * invoked using soft-reset.
cc532915 152 */
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153 if (cpu_isset(cpu, cpus_in_sr))
154 crash_soft_reset_check(cpu);
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155 /* Leave the IPI callback set */
156}
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157
158/*
159 * This function will be called by secondary cpus or by kexec cpu
160 * if soft-reset is activated to stop some CPUs.
161 */
162void crash_kexec_secondary(struct pt_regs *regs)
163{
164 int cpu = smp_processor_id();
165 unsigned long flags;
166 int msecs = 5;
167
168 local_irq_save(flags);
169 /* Wait 5ms if the kexec CPU is not entered yet. */
170 while (crashing_cpu < 0) {
171 if (--msecs < 0) {
172 /*
173 * Either kdump image is not loaded or
174 * kdump process is not started - Probably xmon
175 * exited using 'x'(exit and recover) or
176 * kexec_should_crash() failed for all running tasks.
177 */
178 cpu_clear(cpu, cpus_in_sr);
179 local_irq_restore(flags);
180 return;
181 }
182 mdelay(1);
183 cpu_relax();
184 }
185 if (cpu == crashing_cpu) {
186 /*
187 * Panic CPU will enter this func only via soft-reset.
188 * Wait until all secondary CPUs entered and
189 * then start kexec boot.
190 */
191 crash_soft_reset_check(cpu);
192 cpu_set(crashing_cpu, cpus_in_crash);
193 if (ppc_md.kexec_cpu_down)
194 ppc_md.kexec_cpu_down(1, 0);
195 machine_kexec(kexec_crash_image);
196 /* NOTREACHED */
197 }
198 crash_ipi_callback(regs);
199}
200
cc532915 201#else
c0ce7d08 202static void crash_kexec_prepare_cpus(int cpu)
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203{
204 /*
205 * move the secondarys to us so that we can copy
206 * the new kernel 0-0x100 safely
207 *
208 * do this if kexec in setup.c ?
209 */
b6f35b49 210#ifdef CONFIG_PPC64
cc532915 211 smp_release_cpus();
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212#else
213 /* FIXME */
214#endif
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215}
216
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217void crash_kexec_secondary(struct pt_regs *regs)
218{
219 cpus_in_sr = CPU_MASK_NONE;
220}
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221#endif
222
223void default_machine_crash_shutdown(struct pt_regs *regs)
224{
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225 unsigned int irq;
226
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227 /*
228 * This function is only called after the system
f18190bd 229 * has panicked or is otherwise in a critical state.
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230 * The minimum amount of code to allow a kexec'd kernel
231 * to run successfully needs to happen here.
232 *
233 * In practice this means stopping other cpus in
234 * an SMP system.
235 * The kernel is broken so disable interrupts.
236 */
d04c56f7 237 hard_irq_disable();
cc532915 238
d6c1a908 239 for_each_irq(irq) {
a8553acd 240 struct irq_desc *desc = irq_desc + irq;
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241
242 if (desc->status & IRQ_INPROGRESS)
2e8e8dac 243 desc->chip->eoi(irq);
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244
245 if (!(desc->status & IRQ_DISABLED))
d1bef4ed 246 desc->chip->disable(irq);
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247 }
248
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249 /*
250 * Make a note of crashing cpu. Will be used in machine_kexec
251 * such that another IPI will not be sent.
252 */
253 crashing_cpu = smp_processor_id();
85916f81 254 crash_save_cpu(regs, crashing_cpu);
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255 crash_kexec_prepare_cpus(crashing_cpu);
256 cpu_set(crashing_cpu, cpus_in_crash);
257 if (ppc_md.kexec_cpu_down)
258 ppc_md.kexec_cpu_down(1, 0);
cc532915 259}