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/irq.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/lmb.h>
  34 #include <asm/firmware.h>
  35 #include <asm/smp.h>
  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. */
  45 int crashing_cpu = -1;
  46 static cpumask_t cpus_in_crash = CPU_MASK_NONE;
  47 cpumask_t cpus_in_sr = CPU_MASK_NONE;
  48
  49 static u32 *append_elf_note(u32 *buf, char *name, unsigned type, void *data,
  50                                                                size_t data_len)
  51 {
  52         struct elf_note note;
  53
  54         note.n_namesz = strlen(name) + 1;
  55         note.n_descsz = data_len;
  56         note.n_type   = type;
  57         memcpy(buf, &note, sizeof(note));
  58         buf += (sizeof(note) +3)/4;
  59         memcpy(buf, name, note.n_namesz);
  60         buf += (note.n_namesz + 3)/4;
  61         memcpy(buf, data, note.n_descsz);
  62         buf += (note.n_descsz + 3)/4;
  63
  64         return buf;
  65 }
  66
  67 static void final_note(u32 *buf)
  68 {
  69         struct elf_note note;
  70
  71         note.n_namesz = 0;
  72         note.n_descsz = 0;
  73         note.n_type   = 0;
  74         memcpy(buf, &note, sizeof(note));
  75 }
  76
  77 static void crash_save_this_cpu(struct pt_regs *regs, int cpu)
  78 {
  79         struct elf_prstatus prstatus;
  80         u32 *buf;
  81
  82         if ((cpu < 0) || (cpu >= NR_CPUS))
  83                 return;
  84
  85         /* Using ELF notes here is opportunistic.
  86          * I need a well defined structure format
  87          * for the data I pass, and I need tags
  88          * on the data to indicate what information I have
  89          * squirrelled away.  ELF notes happen to provide
  90          * all of that that no need to invent something new.
  91          */
  92         buf = (u32*)per_cpu_ptr(crash_notes, cpu);
  93         if (!buf)
  94                 return;
  95
  96         memset(&prstatus, 0, sizeof(prstatus));
  97         prstatus.pr_pid = current->pid;
  98         elf_core_copy_regs(&prstatus.pr_reg, regs);
  99         buf = append_elf_note(buf, "CORE", NT_PRSTATUS, &prstatus,
 100                         sizeof(prstatus));
 101         final_note(buf);
 102 }
 103
 104 #ifdef CONFIG_SMP
 105 static atomic_t enter_on_soft_reset = ATOMIC_INIT(0);
 106
 107 void crash_ipi_callback(struct pt_regs *regs)
 108 {
 109         int cpu = smp_processor_id();
 110
 111         if (!cpu_online(cpu))
 112                 return;
 113
 114         local_irq_disable();
 115         if (!cpu_isset(cpu, cpus_in_crash))
 116                 crash_save_this_cpu(regs, cpu);
 117         cpu_set(cpu, cpus_in_crash);
 118
 119         /*
 120          * Entered via soft-reset - could be the kdump
 121          * process is invoked using soft-reset or user activated
 122          * it if some CPU did not respond to an IPI.
 123          * For soft-reset, the secondary CPU can enter this func
 124          * twice. 1 - using IPI, and 2. soft-reset.
 125          * Tell the kexec CPU that entered via soft-reset and ready
 126          * to go down.
 127          */
 128         if (cpu_isset(cpu, cpus_in_sr)) {
 129                 cpu_clear(cpu, cpus_in_sr);
 130                 atomic_inc(&enter_on_soft_reset);
 131         }
 132
 133         /*
 134          * Starting the kdump boot.
 135          * This barrier is needed to make sure that all CPUs are stopped.
 136          * If not, soft-reset will be invoked to bring other CPUs.
 137          */
 138         while (!cpu_isset(crashing_cpu, cpus_in_crash))
 139                 cpu_relax();
 140
 141         if (ppc_md.kexec_cpu_down)
 142                 ppc_md.kexec_cpu_down(1, 1);
 143
 144 #ifdef CONFIG_PPC64
 145         kexec_smp_wait();
 146 #else
 147         for (;;);       /* FIXME */
 148 #endif
 149
 150         /* NOTREACHED */
 151 }
 152
 153 /*
 154  * Wait until all CPUs are entered via soft-reset.
 155  */
 156 static void crash_soft_reset_check(int cpu)
 157 {
 158         unsigned int ncpus = num_online_cpus() - 1;/* Excluding the panic cpu */
 159
 160         cpu_clear(cpu, cpus_in_sr);
 161         while (atomic_read(&enter_on_soft_reset) != ncpus)
 162                 cpu_relax();
 163 }
 164
 165
 166 static void crash_kexec_prepare_cpus(int cpu)
 167 {
 168         unsigned int msecs;
 169
 170         unsigned int ncpus = num_online_cpus() - 1;/* Excluding the panic cpu */
 171
 172         crash_send_ipi(crash_ipi_callback);
 173         smp_wmb();
 174
 175         /*
 176          * FIXME: Until we will have the way to stop other CPUSs reliabally,
 177          * the crash CPU will send an IPI and wait for other CPUs to
 178          * respond.
 179          * Delay of at least 10 seconds.
 180          */
 181         printk(KERN_EMERG "Sending IPI to other cpus...\n");
 182         msecs = 10000;
 183         while ((cpus_weight(cpus_in_crash) < ncpus) && (--msecs > 0)) {
 184                 cpu_relax();
 185                 mdelay(1);
 186         }
 187
 188         /* Would it be better to replace the trap vector here? */
 189
 190         /*
 191          * FIXME: In case if we do not get all CPUs, one possibility: ask the
 192          * user to do soft reset such that we get all.
 193          * Soft-reset will be used until better mechanism is implemented.
 194          */
 195         if (cpus_weight(cpus_in_crash) < ncpus) {
 196                 printk(KERN_EMERG "done waiting: %d cpu(s) not responding\n",
 197                         ncpus - cpus_weight(cpus_in_crash));
 198                 printk(KERN_EMERG "Activate soft-reset to stop other cpu(s)\n");
 199                 cpus_in_sr = CPU_MASK_NONE;
 200                 atomic_set(&enter_on_soft_reset, 0);
 201                 while (cpus_weight(cpus_in_crash) < ncpus)
 202                         cpu_relax();
 203         }
 204         /*
 205          * Make sure all CPUs are entered via soft-reset if the kdump is
 206          * invoked using soft-reset.
 207          */
 208         if (cpu_isset(cpu, cpus_in_sr))
 209                 crash_soft_reset_check(cpu);
 210         /* Leave the IPI callback set */
 211 }
 212
 213 /*
 214  * This function will be called by secondary cpus or by kexec cpu
 215  * if soft-reset is activated to stop some CPUs.
 216  */
 217 void crash_kexec_secondary(struct pt_regs *regs)
 218 {
 219         int cpu = smp_processor_id();
 220         unsigned long flags;
 221         int msecs = 5;
 222
 223         local_irq_save(flags);
 224         /* Wait 5ms if the kexec CPU is not entered yet. */
 225         while (crashing_cpu < 0) {
 226                 if (--msecs < 0) {
 227                         /*
 228                          * Either kdump image is not loaded or
 229                          * kdump process is not started - Probably xmon
 230                          * exited using 'x'(exit and recover) or
 231                          * kexec_should_crash() failed for all running tasks.
 232                          */
 233                         cpu_clear(cpu, cpus_in_sr);
 234                         local_irq_restore(flags);
 235                         return;
 236                 }
 237                 mdelay(1);
 238                 cpu_relax();
 239         }
 240         if (cpu == crashing_cpu) {
 241                 /*
 242                  * Panic CPU will enter this func only via soft-reset.
 243                  * Wait until all secondary CPUs entered and
 244                  * then start kexec boot.
 245                  */
 246                 crash_soft_reset_check(cpu);
 247                 cpu_set(crashing_cpu, cpus_in_crash);
 248                 if (ppc_md.kexec_cpu_down)
 249                         ppc_md.kexec_cpu_down(1, 0);
 250                 machine_kexec(kexec_crash_image);
 251                 /* NOTREACHED */
 252         }
 253         crash_ipi_callback(regs);
 254 }
 255
 256 #else
 257 static void crash_kexec_prepare_cpus(int cpu)
 258 {
 259         /*
 260          * move the secondarys to us so that we can copy
 261          * the new kernel 0-0x100 safely
 262          *
 263          * do this if kexec in setup.c ?
 264          */
 265 #ifdef CONFIG_PPC64
 266         smp_release_cpus();
 267 #else
 268         /* FIXME */
 269 #endif
 270 }
 271
 272 void crash_kexec_secondary(struct pt_regs *regs)
 273 {
 274         cpus_in_sr = CPU_MASK_NONE;
 275 }
 276 #endif
 277
 278 void default_machine_crash_shutdown(struct pt_regs *regs)
 279 {
 280         unsigned int irq;
 281
 282         /*
 283          * This function is only called after the system
 284          * has panicked or is otherwise in a critical state.
 285          * The minimum amount of code to allow a kexec'd kernel
 286          * to run successfully needs to happen here.
 287          *
 288          * In practice this means stopping other cpus in
 289          * an SMP system.
 290          * The kernel is broken so disable interrupts.
 291          */
 292         local_irq_disable();
 293
 294         for_each_irq(irq) {
 295                 struct irq_desc *desc = irq_desc + irq;
 296
 297                 if (desc->status & IRQ_INPROGRESS)
 298                         desc->chip->eoi(irq);
 299
 300                 if (!(desc->status & IRQ_DISABLED))
 301                         desc->chip->disable(irq);
 302         }
 303
 304         /*
 305          * Make a note of crashing cpu. Will be used in machine_kexec
 306          * such that another IPI will not be sent.
 307          */
 308         crashing_cpu = smp_processor_id();
 309         crash_save_this_cpu(regs, crashing_cpu);
 310         crash_kexec_prepare_cpus(crashing_cpu);
 311         cpu_set(crashing_cpu, cpus_in_crash);
 312         if (ppc_md.kexec_cpu_down)
 313                 ppc_md.kexec_cpu_down(1, 0);
 314 }