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/firmware.h>
  27 #include <asm/paca.h>
  28 #include <asm/mmu.h>
  29 #include <asm/sections.h>       /* _end */
  30 #include <asm/prom.h>
  31 #include <asm/smp.h>
  32 #include <asm/hw_breakpoint.h>
  33 #include <asm/asm-prototypes.h>
  34
  35 int default_machine_kexec_prepare(struct kimage *image)
  36 {
  37         int i;
  38         unsigned long begin, end;       /* limits of segment */
  39         unsigned long low, high;        /* limits of blocked memory range */
  40         struct device_node *node;
  41         const unsigned long *basep;
  42         const unsigned int *sizep;
  43
  44         /*
  45          * Since we use the kernel fault handlers and paging code to
  46          * handle the virtual mode, we must make sure no destination
  47          * overlaps kernel static data or bss.
  48          */
  49         for (i = 0; i < image->nr_segments; i++)
  50                 if (image->segment[i].mem < __pa(_end))
  51                         return -ETXTBSY;
  52
  53         /* We also should not overwrite the tce tables */
  54         for_each_node_by_type(node, "pci") {
  55                 basep = of_get_property(node, "linux,tce-base", NULL);
  56                 sizep = of_get_property(node, "linux,tce-size", NULL);
  57                 if (basep == NULL || sizep == NULL)
  58                         continue;
  59
  60                 low = *basep;
  61                 high = low + (*sizep);
  62
  63                 for (i = 0; i < image->nr_segments; i++) {
  64                         begin = image->segment[i].mem;
  65                         end = begin + image->segment[i].memsz;
  66
  67                         if ((begin < high) && (end > low))
  68                                 return -ETXTBSY;
  69                 }
  70         }
  71
  72         return 0;
  73 }
  74
  75 static void copy_segments(unsigned long ind)
  76 {
  77         unsigned long entry;
  78         unsigned long *ptr;
  79         void *dest;
  80         void *addr;
  81
  82         /*
  83          * We rely on kexec_load to create a lists that properly
  84          * initializes these pointers before they are used.
  85          * We will still crash if the list is wrong, but at least
  86          * the compiler will be quiet.
  87          */
  88         ptr = NULL;
  89         dest = NULL;
  90
  91         for (entry = ind; !(entry & IND_DONE); entry = *ptr++) {
  92                 addr = __va(entry & PAGE_MASK);
  93
  94                 switch (entry & IND_FLAGS) {
  95                 case IND_DESTINATION:
  96                         dest = addr;
  97                         break;
  98                 case IND_INDIRECTION:
  99                         ptr = addr;
 100                         break;
 101                 case IND_SOURCE:
 102                         copy_page(dest, addr);
 103                         dest += PAGE_SIZE;
 104                 }
 105         }
 106 }
 107
 108 void kexec_copy_flush(struct kimage *image)
 109 {
 110         long i, nr_segments = image->nr_segments;
 111         struct  kexec_segment ranges[KEXEC_SEGMENT_MAX];
 112
 113         /* save the ranges on the stack to efficiently flush the icache */
 114         memcpy(ranges, image->segment, sizeof(ranges));
 115
 116         /*
 117          * After this call we may not use anything allocated in dynamic
 118          * memory, including *image.
 119          *
 120          * Only globals and the stack are allowed.
 121          */
 122         copy_segments(image->head);
 123
 124         /*
 125          * we need to clear the icache for all dest pages sometime,
 126          * including ones that were in place on the original copy
 127          */
 128         for (i = 0; i < nr_segments; i++)
 129                 flush_icache_range((unsigned long)__va(ranges[i].mem),
 130                         (unsigned long)__va(ranges[i].mem + ranges[i].memsz));
 131 }
 132
 133 #ifdef CONFIG_SMP
 134
 135 static int kexec_all_irq_disabled = 0;
 136
 137 static void kexec_smp_down(void *arg)
 138 {
 139         local_irq_disable();
 140         hard_irq_disable();
 141
 142         mb(); /* make sure our irqs are disabled before we say they are */
 143         get_paca()->kexec_state = KEXEC_STATE_IRQS_OFF;
 144         while(kexec_all_irq_disabled == 0)
 145                 cpu_relax();
 146         mb(); /* make sure all irqs are disabled before this */
 147         hw_breakpoint_disable();
 148         /*
 149          * Now every CPU has IRQs off, we can clear out any pending
 150          * IPIs and be sure that no more will come in after this.
 151          */
 152         if (ppc_md.kexec_cpu_down)
 153                 ppc_md.kexec_cpu_down(0, 1);
 154
 155         kexec_smp_wait();
 156         /* NOTREACHED */
 157 }
 158
 159 static void kexec_prepare_cpus_wait(int wait_state)
 160 {
 161         int my_cpu, i, notified=-1;
 162
 163         hw_breakpoint_disable();
 164         my_cpu = get_cpu();
 165         /* Make sure each CPU has at least made it to the state we need.
 166          *
 167          * FIXME: There is a (slim) chance of a problem if not all of the CPUs
 168          * are correctly onlined.  If somehow we start a CPU on boot with RTAS
 169          * start-cpu, but somehow that CPU doesn't write callin_cpu_map[] in
 170          * time, the boot CPU will timeout.  If it does eventually execute
 171          * stuff, the secondary will start up (paca[].cpu_start was written) and
 172          * get into a peculiar state.  If the platform supports
 173          * smp_ops->take_timebase(), the secondary CPU will probably be spinning
 174          * in there.  If not (i.e. pseries), the secondary will continue on and
 175          * try to online itself/idle/etc. If it survives that, we need to find
 176          * these possible-but-not-online-but-should-be CPUs and chaperone them
 177          * into kexec_smp_wait().
 178          */
 179         for_each_online_cpu(i) {
 180                 if (i == my_cpu)
 181                         continue;
 182
 183                 while (paca[i].kexec_state < wait_state) {
 184                         barrier();
 185                         if (i != notified) {
 186                                 printk(KERN_INFO "kexec: waiting for cpu %d "
 187                                        "(physical %d) to enter %i state\n",
 188                                        i, paca[i].hw_cpu_id, wait_state);
 189                                 notified = i;
 190                         }
 191                 }
 192         }
 193         mb();
 194 }
 195
 196 /*
 197  * We need to make sure each present CPU is online.  The next kernel will scan
 198  * the device tree and assume primary threads are online and query secondary
 199  * threads via RTAS to online them if required.  If we don't online primary
 200  * threads, they will be stuck.  However, we also online secondary threads as we
 201  * may be using 'cede offline'.  In this case RTAS doesn't see the secondary
 202  * threads as offline -- and again, these CPUs will be stuck.
 203  *
 204  * So, we online all CPUs that should be running, including secondary threads.
 205  */
 206 static void wake_offline_cpus(void)
 207 {
 208         int cpu = 0;
 209
 210         for_each_present_cpu(cpu) {
 211                 if (!cpu_online(cpu)) {
 212                         printk(KERN_INFO "kexec: Waking offline cpu %d.\n",
 213                                cpu);
 214                         WARN_ON(cpu_up(cpu));
 215                 }
 216         }
 217 }
 218
 219 static void kexec_prepare_cpus(void)
 220 {
 221         wake_offline_cpus();
 222         smp_call_function(kexec_smp_down, NULL, /* wait */0);
 223         local_irq_disable();
 224         hard_irq_disable();
 225
 226         mb(); /* make sure IRQs are disabled before we say they are */
 227         get_paca()->kexec_state = KEXEC_STATE_IRQS_OFF;
 228
 229         kexec_prepare_cpus_wait(KEXEC_STATE_IRQS_OFF);
 230         /* we are sure every CPU has IRQs off at this point */
 231         kexec_all_irq_disabled = 1;
 232
 233         /* after we tell the others to go down */
 234         if (ppc_md.kexec_cpu_down)
 235                 ppc_md.kexec_cpu_down(0, 0);
 236
 237         /*
 238          * Before removing MMU mappings make sure all CPUs have entered real
 239          * mode:
 240          */
 241         kexec_prepare_cpus_wait(KEXEC_STATE_REAL_MODE);
 242
 243         put_cpu();
 244 }
 245
 246 #else /* ! SMP */
 247
 248 static void kexec_prepare_cpus(void)
 249 {
 250         /*
 251          * move the secondarys to us so that we can copy
 252          * the new kernel 0-0x100 safely
 253          *
 254          * do this if kexec in setup.c ?
 255          *
 256          * We need to release the cpus if we are ever going from an
 257          * UP to an SMP kernel.
 258          */
 259         smp_release_cpus();
 260         if (ppc_md.kexec_cpu_down)
 261                 ppc_md.kexec_cpu_down(0, 0);
 262         local_irq_disable();
 263         hard_irq_disable();
 264 }
 265
 266 #endif /* SMP */
 267
 268 /*
 269  * kexec thread structure and stack.
 270  *
 271  * We need to make sure that this is 16384-byte aligned due to the
 272  * way process stacks are handled.  It also must be statically allocated
 273  * or allocated as part of the kimage, because everything else may be
 274  * overwritten when we copy the kexec image.  We piggyback on the
 275  * "init_task" linker section here to statically allocate a stack.
 276  *
 277  * We could use a smaller stack if we don't care about anything using
 278  * current, but that audit has not been performed.
 279  */
 280 static union thread_union kexec_stack __init_task_data =
 281         { };
 282
 283 /*
 284  * For similar reasons to the stack above, the kexecing CPU needs to be on a
 285  * static PACA; we switch to kexec_paca.
 286  */
 287 struct paca_struct kexec_paca;
 288
 289 /* Our assembly helper, in misc_64.S */
 290 extern void kexec_sequence(void *newstack, unsigned long start,
 291                            void *image, void *control,
 292                            void (*clear_all)(void),
 293                            bool copy_with_mmu_off) __noreturn;
 294
 295 /* too late to fail here */
 296 void default_machine_kexec(struct kimage *image)
 297 {
 298         bool copy_with_mmu_off;
 299
 300         /* prepare control code if any */
 301
 302         /*
 303         * If the kexec boot is the normal one, need to shutdown other cpus
 304         * into our wait loop and quiesce interrupts.
 305         * Otherwise, in the case of crashed mode (crashing_cpu >= 0),
 306         * stopping other CPUs and collecting their pt_regs is done before
 307         * using debugger IPI.
 308         */
 309
 310         if (!kdump_in_progress())
 311                 kexec_prepare_cpus();
 312
 313         printk("kexec: Starting switchover sequence.\n");
 314
 315         /* switch to a staticly allocated stack.  Based on irq stack code.
 316          * We setup preempt_count to avoid using VMX in memcpy.
 317          * XXX: the task struct will likely be invalid once we do the copy!
 318          */
 319         kexec_stack.thread_info.task = current_thread_info()->task;
 320         kexec_stack.thread_info.flags = 0;
 321         kexec_stack.thread_info.preempt_count = HARDIRQ_OFFSET;
 322         kexec_stack.thread_info.cpu = current_thread_info()->cpu;
 323
 324         /* We need a static PACA, too; copy this CPU's PACA over and switch to
 325          * it.  Also poison per_cpu_offset to catch anyone using non-static
 326          * data.
 327          */
 328         memcpy(&kexec_paca, get_paca(), sizeof(struct paca_struct));
 329         kexec_paca.data_offset = 0xedeaddeadeeeeeeeUL;
 330         paca = (struct paca_struct *)RELOC_HIDE(&kexec_paca, 0) -
 331                 kexec_paca.paca_index;
 332         setup_paca(&kexec_paca);
 333
 334         /* XXX: If anyone does 'dynamic lppacas' this will also need to be
 335          * switched to a static version!
 336          */
 337         /*
 338          * On Book3S, the copy must happen with the MMU off if we are either
 339          * using Radix page tables or we are not in an LPAR since we can
 340          * overwrite the page tables while copying.
 341          *
 342          * In an LPAR, we keep the MMU on otherwise we can't access beyond
 343          * the RMA. On BookE there is no real MMU off mode, so we have to
 344          * keep it enabled as well (but then we have bolted TLB entries).
 345          */
 346 #ifdef CONFIG_PPC_BOOK3E
 347         copy_with_mmu_off = false;
 348 #else
 349         copy_with_mmu_off = radix_enabled() ||
 350                 !(firmware_has_feature(FW_FEATURE_LPAR) ||
 351                   firmware_has_feature(FW_FEATURE_PS3_LV1));
 352 #endif
 353
 354         /* Some things are best done in assembly.  Finding globals with
 355          * a toc is easier in C, so pass in what we can.
 356          */
 357         kexec_sequence(&kexec_stack, image->start, image,
 358                        page_address(image->control_code_page),
 359                        mmu_cleanup_all, copy_with_mmu_off);
 360         /* NOTREACHED */
 361 }
 362
 363 #ifdef CONFIG_PPC_BOOK3S_64
 364 /* Values we need to export to the second kernel via the device tree. */
 365 static unsigned long htab_base;
 366 static unsigned long htab_size;
 367
 368 static struct property htab_base_prop = {
 369         .name = "linux,htab-base",
 370         .length = sizeof(unsigned long),
 371         .value = &htab_base,
 372 };
 373
 374 static struct property htab_size_prop = {
 375         .name = "linux,htab-size",
 376         .length = sizeof(unsigned long),
 377         .value = &htab_size,
 378 };
 379
 380 static int __init export_htab_values(void)
 381 {
 382         struct device_node *node;
 383
 384         /* On machines with no htab htab_address is NULL */
 385         if (!htab_address)
 386                 return -ENODEV;
 387
 388         node = of_find_node_by_path("/chosen");
 389         if (!node)
 390                 return -ENODEV;
 391
 392         /* remove any stale propertys so ours can be found */
 393         of_remove_property(node, of_find_property(node, htab_base_prop.name, NULL));
 394         of_remove_property(node, of_find_property(node, htab_size_prop.name, NULL));
 395
 396         htab_base = cpu_to_be64(__pa(htab_address));
 397         of_add_property(node, &htab_base_prop);
 398         htab_size = cpu_to_be64(htab_size_bytes);
 399         of_add_property(node, &htab_size_prop);
 400
 401         of_node_put(node);
 402         return 0;
 403 }
 404 late_initcall(export_htab_values);
 405 #endif /* CONFIG_PPC_BOOK3S_64 */