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