arch/powerpc/kernel/machine_kexec_64.c

   1 /*
   2  * PPC64 code to handle Linux booting another kernel.
   3  *
   4  * Copyright (C) 2004-2005, IBM Corp.
   5  *
   6  * Created by: Milton D Miller II
   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/kexec.h>
  14 #include <linux/smp.h>
  15 #include <linux/thread_info.h>
  16 #include <linux/init_task.h>
  17 #include <linux/errno.h>
  18 #include <linux/kernel.h>
  19 #include <linux/cpu.h>
  20 #include <linux/hardirq.h>
  21
  22 #include <asm/page.h>
  23 #include <asm/current.h>
  24 #include <asm/machdep.h>
  25 #include <asm/cacheflush.h>
  26 #include <asm/paca.h>
  27 #include <asm/mmu.h>
  28 #include <asm/sections.h>       /* _end */
  29 #include <asm/prom.h>
  30 #include <asm/smp.h>
  31 #include <asm/hw_breakpoint.h>
  32
  33 #ifdef CONFIG_PPC_BOOK3E
  34 int default_machine_kexec_prepare(struct kimage *image)
  35 {
  36         int i;
  37         /*
  38          * Since we use the kernel fault handlers and paging code to
  39          * handle the virtual mode, we must make sure no destination
  40          * overlaps kernel static data or bss.
  41          */
  42         for (i = 0; i < image->nr_segments; i++)
  43                 if (image->segment[i].mem < __pa(_end))
  44                         return -ETXTBSY;
  45         return 0;
  46 }
  47 #else
  48 int default_machine_kexec_prepare(struct kimage *image)
  49 {
  50         int i;
  51         unsigned long begin, end;       /* limits of segment */
  52         unsigned long low, high;        /* limits of blocked memory range */
  53         struct device_node *node;
  54         const unsigned long *basep;
  55         const unsigned int *sizep;
  56
  57         if (!ppc_md.hpte_clear_all)
  58                 return -ENOENT;
  59
  60         /*
  61          * Since we use the kernel fault handlers and paging code to
  62          * handle the virtual mode, we must make sure no destination
  63          * overlaps kernel static data or bss.
  64          */
  65         for (i = 0; i < image->nr_segments; i++)
  66                 if (image->segment[i].mem < __pa(_end))
  67                         return -ETXTBSY;
  68
  69         /*
  70          * For non-LPAR, we absolutely can not overwrite the mmu hash
  71          * table, since we are still using the bolted entries in it to
  72          * do the copy.  Check that here.
  73          *
  74          * It is safe if the end is below the start of the blocked
  75          * region (end <= low), or if the beginning is after the
  76          * end of the blocked region (begin >= high).  Use the
  77          * boolean identity !(a || b)  === (!a && !b).
  78          */
  79         if (htab_address) {
  80                 low = __pa(htab_address);
  81                 high = low + htab_size_bytes;
  82
  83                 for (i = 0; i < image->nr_segments; i++) {
  84                         begin = image->segment[i].mem;
  85                         end = begin + image->segment[i].memsz;
  86
  87                         if ((begin < high) && (end > low))
  88                                 return -ETXTBSY;
  89                 }
  90         }
  91
  92         /* We also should not overwrite the tce tables */
  93         for_each_node_by_type(node, "pci") {
  94                 basep = of_get_property(node, "linux,tce-base", NULL);
  95                 sizep = of_get_property(node, "linux,tce-size", NULL);
  96                 if (basep == NULL || sizep == NULL)
  97                         continue;
  98
  99                 low = *basep;
 100                 high = low + (*sizep);
 101
 102                 for (i = 0; i < image->nr_segments; i++) {
 103                         begin = image->segment[i].mem;
 104                         end = begin + image->segment[i].memsz;
 105
 106                         if ((begin < high) && (end > low))
 107                                 return -ETXTBSY;
 108                 }
 109         }
 110
 111         return 0;
 112 }
 113 #endif /* !CONFIG_PPC_BOOK3E */
 114
 115 static void copy_segments(unsigned long ind)
 116 {
 117         unsigned long entry;
 118         unsigned long *ptr;
 119         void *dest;
 120         void *addr;
 121
 122         /*
 123          * We rely on kexec_load to create a lists that properly
 124          * initializes these pointers before they are used.
 125          * We will still crash if the list is wrong, but at least
 126          * the compiler will be quiet.
 127          */
 128         ptr = NULL;
 129         dest = NULL;
 130
 131         for (entry = ind; !(entry & IND_DONE); entry = *ptr++) {
 132                 addr = __va(entry & PAGE_MASK);
 133
 134                 switch (entry & IND_FLAGS) {
 135                 case IND_DESTINATION:
 136                         dest = addr;
 137                         break;
 138                 case IND_INDIRECTION:
 139                         ptr = addr;
 140                         break;
 141                 case IND_SOURCE:
 142                         copy_page(dest, addr);
 143                         dest += PAGE_SIZE;
 144                 }
 145         }
 146 }
 147
 148 void kexec_copy_flush(struct kimage *image)
 149 {
 150         long i, nr_segments = image->nr_segments;
 151         struct  kexec_segment ranges[KEXEC_SEGMENT_MAX];
 152
 153         /* save the ranges on the stack to efficiently flush the icache */
 154         memcpy(ranges, image->segment, sizeof(ranges));
 155
 156         /*
 157          * After this call we may not use anything allocated in dynamic
 158          * memory, including *image.
 159          *
 160          * Only globals and the stack are allowed.
 161          */
 162         copy_segments(image->head);
 163
 164         /*
 165          * we need to clear the icache for all dest pages sometime,
 166          * including ones that were in place on the original copy
 167          */
 168         for (i = 0; i < nr_segments; i++)
 169                 flush_icache_range((unsigned long)__va(ranges[i].mem),
 170                         (unsigned long)__va(ranges[i].mem + ranges[i].memsz));
 171 }
 172
 173 #ifdef CONFIG_SMP
 174
 175 static int kexec_all_irq_disabled = 0;
 176
 177 static void kexec_smp_down(void *arg)
 178 {
 179         local_irq_disable();
 180         hard_irq_disable();
 181
 182         mb(); /* make sure our irqs are disabled before we say they are */
 183         get_paca()->kexec_state = KEXEC_STATE_IRQS_OFF;
 184         while(kexec_all_irq_disabled == 0)
 185                 cpu_relax();
 186         mb(); /* make sure all irqs are disabled before this */
 187         hw_breakpoint_disable();
 188         /*
 189          * Now every CPU has IRQs off, we can clear out any pending
 190          * IPIs and be sure that no more will come in after this.
 191          */
 192         if (ppc_md.kexec_cpu_down)
 193                 ppc_md.kexec_cpu_down(0, 1);
 194
 195         kexec_smp_wait();
 196         /* NOTREACHED */
 197 }
 198
 199 static void kexec_prepare_cpus_wait(int wait_state)
 200 {
 201         int my_cpu, i, notified=-1;
 202
 203         hw_breakpoint_disable();
 204         my_cpu = get_cpu();
 205         /* Make sure each CPU has at least made it to the state we need.
 206          *
 207          * FIXME: There is a (slim) chance of a problem if not all of the CPUs
 208          * are correctly onlined.  If somehow we start a CPU on boot with RTAS
 209          * start-cpu, but somehow that CPU doesn't write callin_cpu_map[] in
 210          * time, the boot CPU will timeout.  If it does eventually execute
 211          * stuff, the secondary will start up (paca[].cpu_start was written) and
 212          * get into a peculiar state.  If the platform supports
 213          * smp_ops->take_timebase(), the secondary CPU will probably be spinning
 214          * in there.  If not (i.e. pseries), the secondary will continue on and
 215          * try to online itself/idle/etc. If it survives that, we need to find
 216          * these possible-but-not-online-but-should-be CPUs and chaperone them
 217          * into kexec_smp_wait().
 218          */
 219         for_each_online_cpu(i) {
 220                 if (i == my_cpu)
 221                         continue;
 222
 223                 while (paca[i].kexec_state < wait_state) {
 224                         barrier();
 225                         if (i != notified) {
 226                                 printk(KERN_INFO "kexec: waiting for cpu %d "
 227                                        "(physical %d) to enter %i state\n",
 228                                        i, paca[i].hw_cpu_id, wait_state);
 229                                 notified = i;
 230                         }
 231                 }
 232         }
 233         mb();
 234 }
 235
 236 /*
 237  * We need to make sure each present CPU is online.  The next kernel will scan
 238  * the device tree and assume primary threads are online and query secondary
 239  * threads via RTAS to online them if required.  If we don't online primary
 240  * threads, they will be stuck.  However, we also online secondary threads as we
 241  * may be using 'cede offline'.  In this case RTAS doesn't see the secondary
 242  * threads as offline -- and again, these CPUs will be stuck.
 243  *
 244  * So, we online all CPUs that should be running, including secondary threads.
 245  */
 246 static void wake_offline_cpus(void)
 247 {
 248         int cpu = 0;
 249
 250         for_each_present_cpu(cpu) {
 251                 if (!cpu_online(cpu)) {
 252                         printk(KERN_INFO "kexec: Waking offline cpu %d.\n",
 253                                cpu);
 254                         WARN_ON(cpu_up(cpu));
 255                 }
 256         }
 257 }
 258
 259 static void kexec_prepare_cpus(void)
 260 {
 261         wake_offline_cpus();
 262         smp_call_function(kexec_smp_down, NULL, /* wait */0);
 263         local_irq_disable();
 264         hard_irq_disable();
 265
 266         mb(); /* make sure IRQs are disabled before we say they are */
 267         get_paca()->kexec_state = KEXEC_STATE_IRQS_OFF;
 268
 269         kexec_prepare_cpus_wait(KEXEC_STATE_IRQS_OFF);
 270         /* we are sure every CPU has IRQs off at this point */
 271         kexec_all_irq_disabled = 1;
 272
 273         /* after we tell the others to go down */
 274         if (ppc_md.kexec_cpu_down)
 275                 ppc_md.kexec_cpu_down(0, 0);
 276
 277         /*
 278          * Before removing MMU mappings make sure all CPUs have entered real
 279          * mode:
 280          */
 281         kexec_prepare_cpus_wait(KEXEC_STATE_REAL_MODE);
 282
 283         put_cpu();
 284 }
 285
 286 #else /* ! SMP */
 287
 288 static void kexec_prepare_cpus(void)
 289 {
 290         /*
 291          * move the secondarys to us so that we can copy
 292          * the new kernel 0-0x100 safely
 293          *
 294          * do this if kexec in setup.c ?
 295          *
 296          * We need to release the cpus if we are ever going from an
 297          * UP to an SMP kernel.
 298          */
 299         smp_release_cpus();
 300         if (ppc_md.kexec_cpu_down)
 301                 ppc_md.kexec_cpu_down(0, 0);
 302         local_irq_disable();
 303         hard_irq_disable();
 304 }
 305
 306 #endif /* SMP */
 307
 308 /*
 309  * kexec thread structure and stack.
 310  *
 311  * We need to make sure that this is 16384-byte aligned due to the
 312  * way process stacks are handled.  It also must be statically allocated
 313  * or allocated as part of the kimage, because everything else may be
 314  * overwritten when we copy the kexec image.  We piggyback on the
 315  * "init_task" linker section here to statically allocate a stack.
 316  *
 317  * We could use a smaller stack if we don't care about anything using
 318  * current, but that audit has not been performed.
 319  */
 320 static union thread_union kexec_stack __init_task_data =
 321         { };
 322
 323 /*
 324  * For similar reasons to the stack above, the kexecing CPU needs to be on a
 325  * static PACA; we switch to kexec_paca.
 326  */
 327 struct paca_struct kexec_paca;
 328
 329 /* Our assembly helper, in misc_64.S */
 330 extern void kexec_sequence(void *newstack, unsigned long start,
 331                            void *image, void *control,
 332                            void (*clear_all)(void)) __noreturn;
 333
 334 /* too late to fail here */
 335 void default_machine_kexec(struct kimage *image)
 336 {
 337         /* prepare control code if any */
 338
 339         /*
 340         * If the kexec boot is the normal one, need to shutdown other cpus
 341         * into our wait loop and quiesce interrupts.
 342         * Otherwise, in the case of crashed mode (crashing_cpu >= 0),
 343         * stopping other CPUs and collecting their pt_regs is done before
 344         * using debugger IPI.
 345         */
 346
 347         if (!kdump_in_progress())
 348                 kexec_prepare_cpus();
 349
 350         pr_debug("kexec: Starting switchover sequence.\n");
 351
 352         /* switch to a staticly allocated stack.  Based on irq stack code.
 353          * We setup preempt_count to avoid using VMX in memcpy.
 354          * XXX: the task struct will likely be invalid once we do the copy!
 355          */
 356         kexec_stack.thread_info.task = current_thread_info()->task;
 357         kexec_stack.thread_info.flags = 0;
 358         kexec_stack.thread_info.preempt_count = HARDIRQ_OFFSET;
 359         kexec_stack.thread_info.cpu = current_thread_info()->cpu;
 360
 361         /* We need a static PACA, too; copy this CPU's PACA over and switch to
 362          * it.  Also poison per_cpu_offset to catch anyone using non-static
 363          * data.
 364          */
 365         memcpy(&kexec_paca, get_paca(), sizeof(struct paca_struct));
 366         kexec_paca.data_offset = 0xedeaddeadeeeeeeeUL;
 367         paca = (struct paca_struct *)RELOC_HIDE(&kexec_paca, 0) -
 368                 kexec_paca.paca_index;
 369         setup_paca(&kexec_paca);
 370
 371         /* XXX: If anyone does 'dynamic lppacas' this will also need to be
 372          * switched to a static version!
 373          */
 374
 375         /* Some things are best done in assembly.  Finding globals with
 376          * a toc is easier in C, so pass in what we can.
 377          */
 378         kexec_sequence(&kexec_stack, image->start, image,
 379                         page_address(image->control_code_page),
 380                         ppc_md.hpte_clear_all);
 381         /* NOTREACHED */
 382 }
 383
 384 #ifndef CONFIG_PPC_BOOK3E
 385 /* Values we need to export to the second kernel via the device tree. */
 386 static unsigned long htab_base;
 387 static unsigned long htab_size;
 388
 389 static struct property htab_base_prop = {
 390         .name = "linux,htab-base",
 391         .length = sizeof(unsigned long),
 392         .value = &htab_base,
 393 };
 394
 395 static struct property htab_size_prop = {
 396         .name = "linux,htab-size",
 397         .length = sizeof(unsigned long),
 398         .value = &htab_size,
 399 };
 400
 401 static int __init export_htab_values(void)
 402 {
 403         struct device_node *node;
 404         struct property *prop;
 405
 406         /* On machines with no htab htab_address is NULL */
 407         if (!htab_address)
 408                 return -ENODEV;
 409
 410         node = of_find_node_by_path("/chosen");
 411         if (!node)
 412                 return -ENODEV;
 413
 414         /* remove any stale propertys so ours can be found */
 415         prop = of_find_property(node, htab_base_prop.name, NULL);
 416         if (prop)
 417                 of_remove_property(node, prop);
 418         prop = of_find_property(node, htab_size_prop.name, NULL);
 419         if (prop)
 420                 of_remove_property(node, prop);
 421
 422         htab_base = cpu_to_be64(__pa(htab_address));
 423         of_add_property(node, &htab_base_prop);
 424         htab_size = cpu_to_be64(htab_size_bytes);
 425         of_add_property(node, &htab_size_prop);
 426
 427         of_node_put(node);
 428         return 0;
 429 }
 430 late_initcall(export_htab_values);
 431 #endif /* !CONFIG_PPC_BOOK3E */