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 #include <linux/kernel.h>
14 #include <linux/smp.h>
15 #include <linux/reboot.h>
16 #include <linux/kexec.h>
17 #include <linux/export.h>
18 #include <linux/crash_dump.h>
19 #include <linux/delay.h>
20 #include <linux/irq.h>
21 #include <linux/types.h>
22
23 #include <asm/processor.h>
24 #include <asm/machdep.h>
25 #include <asm/kexec.h>
26 #include <asm/kdump.h>
27 #include <asm/prom.h>
28 #include <asm/smp.h>
29 #include <asm/setjmp.h>
30 #include <asm/debug.h>
31
32 /*
33 * The primary CPU waits a while for all secondary CPUs to enter. This is to
34 * avoid sending an IPI if the secondary CPUs are entering
35 * crash_kexec_secondary on their own (eg via a system reset).
36 *
37 * The secondary timeout has to be longer than the primary. Both timeouts are
38 * in milliseconds.
39 */
40 #define PRIMARY_TIMEOUT 500
41 #define SECONDARY_TIMEOUT 1000
42
43 #define IPI_TIMEOUT 10000
44 #define REAL_MODE_TIMEOUT 10000
45
46 /* This keeps a track of which one is the crashing cpu. */
47 int crashing_cpu = -1;
48 static int time_to_dump;
49
50 #define CRASH_HANDLER_MAX 3
51 /* NULL terminated list of shutdown handles */
52 static crash_shutdown_t crash_shutdown_handles[CRASH_HANDLER_MAX+1];
53 static DEFINE_SPINLOCK(crash_handlers_lock);
54
55 static unsigned long crash_shutdown_buf[JMP_BUF_LEN];
56 static int crash_shutdown_cpu = -1;
57
handle_fault(struct pt_regs * regs)58 static int handle_fault(struct pt_regs *regs)
59 {
60 if (crash_shutdown_cpu == smp_processor_id())
61 longjmp(crash_shutdown_buf, 1);
62 return 0;
63 }
64
65 #ifdef CONFIG_SMP
66
67 static atomic_t cpus_in_crash;
crash_ipi_callback(struct pt_regs * regs)68 void crash_ipi_callback(struct pt_regs *regs)
69 {
70 static cpumask_t cpus_state_saved = CPU_MASK_NONE;
71
72 int cpu = smp_processor_id();
73
74 if (!cpu_online(cpu))
75 return;
76
77 hard_irq_disable();
78 if (!cpumask_test_cpu(cpu, &cpus_state_saved)) {
79 crash_save_cpu(regs, cpu);
80 cpumask_set_cpu(cpu, &cpus_state_saved);
81 }
82
83 atomic_inc(&cpus_in_crash);
84 smp_mb__after_atomic();
85
86 /*
87 * Starting the kdump boot.
88 * This barrier is needed to make sure that all CPUs are stopped.
89 */
90 while (!time_to_dump)
91 cpu_relax();
92
93 if (ppc_md.kexec_cpu_down)
94 ppc_md.kexec_cpu_down(1, 1);
95
96 #ifdef CONFIG_PPC64
97 kexec_smp_wait();
98 #else
99 for (;;); /* FIXME */
100 #endif
101
102 /* NOTREACHED */
103 }
104
crash_kexec_prepare_cpus(int cpu)105 static void crash_kexec_prepare_cpus(int cpu)
106 {
107 unsigned int msecs;
108 unsigned int ncpus = num_online_cpus() - 1;/* Excluding the panic cpu */
109 int tries = 0;
110 int (*old_handler)(struct pt_regs *regs);
111
112 printk(KERN_EMERG "Sending IPI to other CPUs\n");
113
114 crash_send_ipi(crash_ipi_callback);
115 smp_wmb();
116
117 again:
118 /*
119 * FIXME: Until we will have the way to stop other CPUs reliably,
120 * the crash CPU will send an IPI and wait for other CPUs to
121 * respond.
122 */
123 msecs = IPI_TIMEOUT;
124 while ((atomic_read(&cpus_in_crash) < ncpus) && (--msecs > 0))
125 mdelay(1);
126
127 /* Would it be better to replace the trap vector here? */
128
129 if (atomic_read(&cpus_in_crash) >= ncpus) {
130 printk(KERN_EMERG "IPI complete\n");
131 return;
132 }
133
134 printk(KERN_EMERG "ERROR: %d cpu(s) not responding\n",
135 ncpus - atomic_read(&cpus_in_crash));
136
137 /*
138 * If we have a panic timeout set then we can't wait indefinitely
139 * for someone to activate system reset. We also give up on the
140 * second time through if system reset fail to work.
141 */
142 if ((panic_timeout > 0) || (tries > 0))
143 return;
144
145 /*
146 * A system reset will cause all CPUs to take an 0x100 exception.
147 * The primary CPU returns here via setjmp, and the secondary
148 * CPUs reexecute the crash_kexec_secondary path.
149 */
150 old_handler = __debugger;
151 __debugger = handle_fault;
152 crash_shutdown_cpu = smp_processor_id();
153
154 if (setjmp(crash_shutdown_buf) == 0) {
155 printk(KERN_EMERG "Activate system reset (dumprestart) "
156 "to stop other cpu(s)\n");
157
158 /*
159 * A system reset will force all CPUs to execute the
160 * crash code again. We need to reset cpus_in_crash so we
161 * wait for everyone to do this.
162 */
163 atomic_set(&cpus_in_crash, 0);
164 smp_mb();
165
166 while (atomic_read(&cpus_in_crash) < ncpus)
167 cpu_relax();
168 }
169
170 crash_shutdown_cpu = -1;
171 __debugger = old_handler;
172
173 tries++;
174 goto again;
175 }
176
177 /*
178 * This function will be called by secondary cpus.
179 */
crash_kexec_secondary(struct pt_regs * regs)180 void crash_kexec_secondary(struct pt_regs *regs)
181 {
182 unsigned long flags;
183 int msecs = SECONDARY_TIMEOUT;
184
185 local_irq_save(flags);
186
187 /* Wait for the primary crash CPU to signal its progress */
188 while (crashing_cpu < 0) {
189 if (--msecs < 0) {
190 /* No response, kdump image may not have been loaded */
191 local_irq_restore(flags);
192 return;
193 }
194
195 mdelay(1);
196 }
197
198 crash_ipi_callback(regs);
199 }
200
201 #else /* ! CONFIG_SMP */
202
crash_kexec_prepare_cpus(int cpu)203 static void crash_kexec_prepare_cpus(int cpu)
204 {
205 /*
206 * move the secondaries to us so that we can copy
207 * the new kernel 0-0x100 safely
208 *
209 * do this if kexec in setup.c ?
210 */
211 #ifdef CONFIG_PPC64
212 smp_release_cpus();
213 #else
214 /* FIXME */
215 #endif
216 }
217
crash_kexec_secondary(struct pt_regs * regs)218 void crash_kexec_secondary(struct pt_regs *regs)
219 {
220 }
221 #endif /* CONFIG_SMP */
222
223 /* wait for all the CPUs to hit real mode but timeout if they don't come in */
224 #if defined(CONFIG_SMP) && defined(CONFIG_PPC_STD_MMU_64)
crash_kexec_wait_realmode(int cpu)225 static void crash_kexec_wait_realmode(int cpu)
226 {
227 unsigned int msecs;
228 int i;
229
230 msecs = REAL_MODE_TIMEOUT;
231 for (i=0; i < nr_cpu_ids && msecs > 0; i++) {
232 if (i == cpu)
233 continue;
234
235 while (paca[i].kexec_state < KEXEC_STATE_REAL_MODE) {
236 barrier();
237 if (!cpu_possible(i) || !cpu_online(i) || (msecs <= 0))
238 break;
239 msecs--;
240 mdelay(1);
241 }
242 }
243 mb();
244 }
245 #else
crash_kexec_wait_realmode(int cpu)246 static inline void crash_kexec_wait_realmode(int cpu) {}
247 #endif /* CONFIG_SMP && CONFIG_PPC_STD_MMU_64 */
248
249 /*
250 * Register a function to be called on shutdown. Only use this if you
251 * can't reset your device in the second kernel.
252 */
crash_shutdown_register(crash_shutdown_t handler)253 int crash_shutdown_register(crash_shutdown_t handler)
254 {
255 unsigned int i, rc;
256
257 spin_lock(&crash_handlers_lock);
258 for (i = 0 ; i < CRASH_HANDLER_MAX; i++)
259 if (!crash_shutdown_handles[i]) {
260 /* Insert handle at first empty entry */
261 crash_shutdown_handles[i] = handler;
262 rc = 0;
263 break;
264 }
265
266 if (i == CRASH_HANDLER_MAX) {
267 printk(KERN_ERR "Crash shutdown handles full, "
268 "not registered.\n");
269 rc = 1;
270 }
271
272 spin_unlock(&crash_handlers_lock);
273 return rc;
274 }
275 EXPORT_SYMBOL(crash_shutdown_register);
276
crash_shutdown_unregister(crash_shutdown_t handler)277 int crash_shutdown_unregister(crash_shutdown_t handler)
278 {
279 unsigned int i, rc;
280
281 spin_lock(&crash_handlers_lock);
282 for (i = 0 ; i < CRASH_HANDLER_MAX; i++)
283 if (crash_shutdown_handles[i] == handler)
284 break;
285
286 if (i == CRASH_HANDLER_MAX) {
287 printk(KERN_ERR "Crash shutdown handle not found\n");
288 rc = 1;
289 } else {
290 /* Shift handles down */
291 for (; crash_shutdown_handles[i]; i++)
292 crash_shutdown_handles[i] =
293 crash_shutdown_handles[i+1];
294 rc = 0;
295 }
296
297 spin_unlock(&crash_handlers_lock);
298 return rc;
299 }
300 EXPORT_SYMBOL(crash_shutdown_unregister);
301
default_machine_crash_shutdown(struct pt_regs * regs)302 void default_machine_crash_shutdown(struct pt_regs *regs)
303 {
304 unsigned int i;
305 int (*old_handler)(struct pt_regs *regs);
306
307 /*
308 * This function is only called after the system
309 * has panicked or is otherwise in a critical state.
310 * The minimum amount of code to allow a kexec'd kernel
311 * to run successfully needs to happen here.
312 *
313 * In practice this means stopping other cpus in
314 * an SMP system.
315 * The kernel is broken so disable interrupts.
316 */
317 hard_irq_disable();
318
319 /*
320 * Make a note of crashing cpu. Will be used in machine_kexec
321 * such that another IPI will not be sent.
322 */
323 crashing_cpu = smp_processor_id();
324
325 /*
326 * If we came in via system reset, wait a while for the secondary
327 * CPUs to enter.
328 */
329 if (TRAP(regs) == 0x100)
330 mdelay(PRIMARY_TIMEOUT);
331
332 crash_kexec_prepare_cpus(crashing_cpu);
333
334 crash_save_cpu(regs, crashing_cpu);
335
336 time_to_dump = 1;
337
338 crash_kexec_wait_realmode(crashing_cpu);
339
340 machine_kexec_mask_interrupts();
341
342 /*
343 * Call registered shutdown routines safely. Swap out
344 * __debugger_fault_handler, and replace on exit.
345 */
346 old_handler = __debugger_fault_handler;
347 __debugger_fault_handler = handle_fault;
348 crash_shutdown_cpu = smp_processor_id();
349 for (i = 0; crash_shutdown_handles[i]; i++) {
350 if (setjmp(crash_shutdown_buf) == 0) {
351 /*
352 * Insert syncs and delay to ensure
353 * instructions in the dangerous region don't
354 * leak away from this protected region.
355 */
356 asm volatile("sync; isync");
357 /* dangerous region */
358 crash_shutdown_handles[i]();
359 asm volatile("sync; isync");
360 }
361 }
362 crash_shutdown_cpu = -1;
363 __debugger_fault_handler = old_handler;
364
365 if (ppc_md.kexec_cpu_down)
366 ppc_md.kexec_cpu_down(1, 0);
367 }
368