arch/powerpc/kernel/crash.c

   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/export.h>
  21 #include <linux/crash_dump.h>
  22 #include <linux/delay.h>
  23 #include <linux/elf.h>
  24 #include <linux/elfcore.h>
  25 #include <linux/init.h>
  26 #include <linux/irq.h>
  27 #include <linux/types.h>
  28 #include <linux/memblock.h>
  29
  30 #include <asm/processor.h>
  31 #include <asm/machdep.h>
  32 #include <asm/kexec.h>
  33 #include <asm/kdump.h>
  34 #include <asm/prom.h>
  35 #include <asm/firmware.h>
  36 #include <asm/smp.h>
  37 #include <asm/system.h>
  38 #include <asm/setjmp.h>
  39
  40 #ifdef DEBUG
  41 #include <asm/udbg.h>
  42 #define DBG(fmt...) udbg_printf(fmt)
  43 #else
  44 #define DBG(fmt...)
  45 #endif
  46
  47 /* This keeps a track of which one is crashing cpu. */
  48 int crashing_cpu = -1;
  49 static cpumask_t cpus_in_crash = CPU_MASK_NONE;
  50 cpumask_t cpus_in_sr = CPU_MASK_NONE;
  51
  52 #define CRASH_HANDLER_MAX 3
  53 /* NULL terminated list of shutdown handles */
  54 static crash_shutdown_t crash_shutdown_handles[CRASH_HANDLER_MAX+1];
  55 static DEFINE_SPINLOCK(crash_handlers_lock);
  56
  57 #ifdef CONFIG_SMP
  58 static atomic_t enter_on_soft_reset = ATOMIC_INIT(0);
  59
  60 void crash_ipi_callback(struct pt_regs *regs)
  61 {
  62         int cpu = smp_processor_id();
  63
  64         if (!cpu_online(cpu))
  65                 return;
  66
  67         hard_irq_disable();
  68         if (!cpumask_test_cpu(cpu, &cpus_in_crash))
  69                 crash_save_cpu(regs, cpu);
  70         cpumask_set_cpu(cpu, &cpus_in_crash);
  71
  72         /*
  73          * Entered via soft-reset - could be the kdump
  74          * process is invoked using soft-reset or user activated
  75          * it if some CPU did not respond to an IPI.
  76          * For soft-reset, the secondary CPU can enter this func
  77          * twice. 1 - using IPI, and 2. soft-reset.
  78          * Tell the kexec CPU that entered via soft-reset and ready
  79          * to go down.
  80          */
  81         if (cpumask_test_cpu(cpu, &cpus_in_sr)) {
  82                 cpumask_clear_cpu(cpu, &cpus_in_sr);
  83                 atomic_inc(&enter_on_soft_reset);
  84         }
  85
  86         /*
  87          * Starting the kdump boot.
  88          * This barrier is needed to make sure that all CPUs are stopped.
  89          * If not, soft-reset will be invoked to bring other CPUs.
  90          */
  91         while (!cpumask_test_cpu(crashing_cpu, &cpus_in_crash))
  92                 cpu_relax();
  93
  94         if (ppc_md.kexec_cpu_down)
  95                 ppc_md.kexec_cpu_down(1, 1);
  96
  97 #ifdef CONFIG_PPC64
  98         kexec_smp_wait();
  99 #else
 100         for (;;);       /* FIXME */
 101 #endif
 102
 103         /* NOTREACHED */
 104 }
 105
 106 /*
 107  * Wait until all CPUs are entered via soft-reset.
 108  */
 109 static void crash_soft_reset_check(int cpu)
 110 {
 111         unsigned int ncpus = num_online_cpus() - 1;/* Excluding the panic cpu */
 112
 113         cpumask_clear_cpu(cpu, &cpus_in_sr);
 114         while (atomic_read(&enter_on_soft_reset) != ncpus)
 115                 cpu_relax();
 116 }
 117
 118
 119 static void crash_kexec_prepare_cpus(int cpu)
 120 {
 121         unsigned int msecs;
 122
 123         unsigned int ncpus = num_online_cpus() - 1;/* Excluding the panic cpu */
 124
 125         crash_send_ipi(crash_ipi_callback);
 126         smp_wmb();
 127
 128         /*
 129          * FIXME: Until we will have the way to stop other CPUs reliably,
 130          * the crash CPU will send an IPI and wait for other CPUs to
 131          * respond.
 132          * Delay of at least 10 seconds.
 133          */
 134         printk(KERN_EMERG "Sending IPI to other cpus...\n");
 135         msecs = 10000;
 136         while ((cpumask_weight(&cpus_in_crash) < ncpus) && (--msecs > 0)) {
 137                 cpu_relax();
 138                 mdelay(1);
 139         }
 140
 141         /* Would it be better to replace the trap vector here? */
 142
 143         /*
 144          * FIXME: In case if we do not get all CPUs, one possibility: ask the
 145          * user to do soft reset such that we get all.
 146          * Soft-reset will be used until better mechanism is implemented.
 147          */
 148         if (cpumask_weight(&cpus_in_crash) < ncpus) {
 149                 printk(KERN_EMERG "done waiting: %d cpu(s) not responding\n",
 150                         ncpus - cpumask_weight(&cpus_in_crash));
 151                 printk(KERN_EMERG "Activate soft-reset to stop other cpu(s)\n");
 152                 cpumask_clear(&cpus_in_sr);
 153                 atomic_set(&enter_on_soft_reset, 0);
 154                 while (cpumask_weight(&cpus_in_crash) < ncpus)
 155                         cpu_relax();
 156         }
 157         /*
 158          * Make sure all CPUs are entered via soft-reset if the kdump is
 159          * invoked using soft-reset.
 160          */
 161         if (cpumask_test_cpu(cpu, &cpus_in_sr))
 162                 crash_soft_reset_check(cpu);
 163         /* Leave the IPI callback set */
 164 }
 165
 166 /*
 167  * This function will be called by secondary cpus or by kexec cpu
 168  * if soft-reset is activated to stop some CPUs.
 169  */
 170 void crash_kexec_secondary(struct pt_regs *regs)
 171 {
 172         int cpu = smp_processor_id();
 173         unsigned long flags;
 174         int msecs = 5;
 175
 176         local_irq_save(flags);
 177         /* Wait 5ms if the kexec CPU is not entered yet. */
 178         while (crashing_cpu < 0) {
 179                 if (--msecs < 0) {
 180                         /*
 181                          * Either kdump image is not loaded or
 182                          * kdump process is not started - Probably xmon
 183                          * exited using 'x'(exit and recover) or
 184                          * kexec_should_crash() failed for all running tasks.
 185                          */
 186                         cpumask_clear_cpu(cpu, &cpus_in_sr);
 187                         local_irq_restore(flags);
 188                         return;
 189                 }
 190                 mdelay(1);
 191                 cpu_relax();
 192         }
 193         if (cpu == crashing_cpu) {
 194                 /*
 195                  * Panic CPU will enter this func only via soft-reset.
 196                  * Wait until all secondary CPUs entered and
 197                  * then start kexec boot.
 198                  */
 199                 crash_soft_reset_check(cpu);
 200                 cpumask_set_cpu(crashing_cpu, &cpus_in_crash);
 201                 if (ppc_md.kexec_cpu_down)
 202                         ppc_md.kexec_cpu_down(1, 0);
 203                 machine_kexec(kexec_crash_image);
 204                 /* NOTREACHED */
 205         }
 206         crash_ipi_callback(regs);
 207 }
 208
 209 #else   /* ! CONFIG_SMP */
 210
 211 static void crash_kexec_prepare_cpus(int cpu)
 212 {
 213         /*
 214          * move the secondarys to us so that we can copy
 215          * the new kernel 0-0x100 safely
 216          *
 217          * do this if kexec in setup.c ?
 218          */
 219 #ifdef CONFIG_PPC64
 220         smp_release_cpus();
 221 #else
 222         /* FIXME */
 223 #endif
 224 }
 225
 226 void crash_kexec_secondary(struct pt_regs *regs)
 227 {
 228         cpumask_clear(&cpus_in_sr);
 229 }
 230 #endif  /* CONFIG_SMP */
 231
 232 /* wait for all the CPUs to hit real mode but timeout if they don't come in */
 233 #if defined(CONFIG_SMP) && defined(CONFIG_PPC_STD_MMU_64)
 234 static void crash_kexec_wait_realmode(int cpu)
 235 {
 236         unsigned int msecs;
 237         int i;
 238
 239         msecs = 10000;
 240         for (i=0; i < nr_cpu_ids && msecs > 0; i++) {
 241                 if (i == cpu)
 242                         continue;
 243
 244                 while (paca[i].kexec_state < KEXEC_STATE_REAL_MODE) {
 245                         barrier();
 246                         if (!cpu_possible(i) || !cpu_online(i) || (msecs <= 0))
 247                                 break;
 248                         msecs--;
 249                         mdelay(1);
 250                 }
 251         }
 252         mb();
 253 }
 254 #else
 255 static inline void crash_kexec_wait_realmode(int cpu) {}
 256 #endif  /* CONFIG_SMP && CONFIG_PPC_STD_MMU_64 */
 257
 258 /*
 259  * Register a function to be called on shutdown.  Only use this if you
 260  * can't reset your device in the second kernel.
 261  */
 262 int crash_shutdown_register(crash_shutdown_t handler)
 263 {
 264         unsigned int i, rc;
 265
 266         spin_lock(&crash_handlers_lock);
 267         for (i = 0 ; i < CRASH_HANDLER_MAX; i++)
 268                 if (!crash_shutdown_handles[i]) {
 269                         /* Insert handle at first empty entry */
 270                         crash_shutdown_handles[i] = handler;
 271                         rc = 0;
 272                         break;
 273                 }
 274
 275         if (i == CRASH_HANDLER_MAX) {
 276                 printk(KERN_ERR "Crash shutdown handles full, "
 277                        "not registered.\n");
 278                 rc = 1;
 279         }
 280
 281         spin_unlock(&crash_handlers_lock);
 282         return rc;
 283 }
 284 EXPORT_SYMBOL(crash_shutdown_register);
 285
 286 int crash_shutdown_unregister(crash_shutdown_t handler)
 287 {
 288         unsigned int i, rc;
 289
 290         spin_lock(&crash_handlers_lock);
 291         for (i = 0 ; i < CRASH_HANDLER_MAX; i++)
 292                 if (crash_shutdown_handles[i] == handler)
 293                         break;
 294
 295         if (i == CRASH_HANDLER_MAX) {
 296                 printk(KERN_ERR "Crash shutdown handle not found\n");
 297                 rc = 1;
 298         } else {
 299                 /* Shift handles down */
 300                 for (; crash_shutdown_handles[i]; i++)
 301                         crash_shutdown_handles[i] =
 302                                 crash_shutdown_handles[i+1];
 303                 rc = 0;
 304         }
 305
 306         spin_unlock(&crash_handlers_lock);
 307         return rc;
 308 }
 309 EXPORT_SYMBOL(crash_shutdown_unregister);
 310
 311 static unsigned long crash_shutdown_buf[JMP_BUF_LEN];
 312 static int crash_shutdown_cpu = -1;
 313
 314 static int handle_fault(struct pt_regs *regs)
 315 {
 316         if (crash_shutdown_cpu == smp_processor_id())
 317                 longjmp(crash_shutdown_buf, 1);
 318         return 0;
 319 }
 320
 321 void default_machine_crash_shutdown(struct pt_regs *regs)
 322 {
 323         unsigned int i;
 324         int (*old_handler)(struct pt_regs *regs);
 325
 326
 327         /*
 328          * This function is only called after the system
 329          * has panicked or is otherwise in a critical state.
 330          * The minimum amount of code to allow a kexec'd kernel
 331          * to run successfully needs to happen here.
 332          *
 333          * In practice this means stopping other cpus in
 334          * an SMP system.
 335          * The kernel is broken so disable interrupts.
 336          */
 337         hard_irq_disable();
 338
 339         /*
 340          * Make a note of crashing cpu. Will be used in machine_kexec
 341          * such that another IPI will not be sent.
 342          */
 343         crashing_cpu = smp_processor_id();
 344         crash_save_cpu(regs, crashing_cpu);
 345         crash_kexec_prepare_cpus(crashing_cpu);
 346         cpumask_set_cpu(crashing_cpu, &cpus_in_crash);
 347         crash_kexec_wait_realmode(crashing_cpu);
 348
 349         machine_kexec_mask_interrupts();
 350
 351         /*
 352          * Call registered shutdown routines savely.  Swap out
 353          * __debugger_fault_handler, and replace on exit.
 354          */
 355         old_handler = __debugger_fault_handler;
 356         __debugger_fault_handler = handle_fault;
 357         crash_shutdown_cpu = smp_processor_id();
 358         for (i = 0; crash_shutdown_handles[i]; i++) {
 359                 if (setjmp(crash_shutdown_buf) == 0) {
 360                         /*
 361                          * Insert syncs and delay to ensure
 362                          * instructions in the dangerous region don't
 363                          * leak away from this protected region.
 364                          */
 365                         asm volatile("sync; isync");
 366                         /* dangerous region */
 367                         crash_shutdown_handles[i]();
 368                         asm volatile("sync; isync");
 369                 }
 370         }
 371         crash_shutdown_cpu = -1;
 372         __debugger_fault_handler = old_handler;
 373
 374         if (ppc_md.kexec_cpu_down)
 375                 ppc_md.kexec_cpu_down(1, 0);
 376 }