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machine_kexec_64.c

/*
 * PPC64 code to handle Linux booting another kernel.
 *
 * Copyright (C) 2004-2005, IBM Corp.
 *
 * Created by: Milton D Miller II
 *
 * This source code is licensed under the GNU General Public License,
 * Version 2.  See the file COPYING for more details.
 */


#include <linux/kexec.h>
#include <linux/smp.h>
#include <linux/thread_info.h>
#include <linux/errno.h>

#include <asm/page.h>
#include <asm/current.h>
#include <asm/machdep.h>
#include <asm/cacheflush.h>
#include <asm/paca.h>
#include <asm/mmu.h>
#include <asm/sections.h>     /* _end */
#include <asm/prom.h>
#include <asm/smp.h>

int default_machine_kexec_prepare(struct kimage *image)
{
      int i;
      unsigned long begin, end;     /* limits of segment */
      unsigned long low, high;      /* limits of blocked memory range */
      struct device_node *node;
      const unsigned long *basep;
      const unsigned int *sizep;

      if (!ppc_md.hpte_clear_all)
            return -ENOENT;

      /*
       * Since we use the kernel fault handlers and paging code to
       * handle the virtual mode, we must make sure no destination
       * overlaps kernel static data or bss.
       */
      for (i = 0; i < image->nr_segments; i++)
            if (image->segment[i].mem < __pa(_end))
                  return -ETXTBSY;

      /*
       * For non-LPAR, we absolutely can not overwrite the mmu hash
       * table, since we are still using the bolted entries in it to
       * do the copy.  Check that here.
       *
       * It is safe if the end is below the start of the blocked
       * region (end <= low), or if the beginning is after the
       * end of the blocked region (begin >= high).  Use the
       * boolean identity !(a || b)  === (!a && !b).
       */
      if (htab_address) {
            low = __pa(htab_address);
            high = low + htab_size_bytes;

            for (i = 0; i < image->nr_segments; i++) {
                  begin = image->segment[i].mem;
                  end = begin + image->segment[i].memsz;

                  if ((begin < high) && (end > low))
                        return -ETXTBSY;
            }
      }

      /* We also should not overwrite the tce tables */
      for (node = of_find_node_by_type(NULL, "pci"); node != NULL;
                  node = of_find_node_by_type(node, "pci")) {
            basep = of_get_property(node, "linux,tce-base", NULL);
            sizep = of_get_property(node, "linux,tce-size", NULL);
            if (basep == NULL || sizep == NULL)
                  continue;

            low = *basep;
            high = low + (*sizep);

            for (i = 0; i < image->nr_segments; i++) {
                  begin = image->segment[i].mem;
                  end = begin + image->segment[i].memsz;

                  if ((begin < high) && (end > low))
                        return -ETXTBSY;
            }
      }

      return 0;
}

#define IND_FLAGS (IND_DESTINATION | IND_INDIRECTION | IND_DONE | IND_SOURCE)

static void copy_segments(unsigned long ind)
{
      unsigned long entry;
      unsigned long *ptr;
      void *dest;
      void *addr;

      /*
       * We rely on kexec_load to create a lists that properly
       * initializes these pointers before they are used.
       * We will still crash if the list is wrong, but at least
       * the compiler will be quiet.
       */
      ptr = NULL;
      dest = NULL;

      for (entry = ind; !(entry & IND_DONE); entry = *ptr++) {
            addr = __va(entry & PAGE_MASK);

            switch (entry & IND_FLAGS) {
            case IND_DESTINATION:
                  dest = addr;
                  break;
            case IND_INDIRECTION:
                  ptr = addr;
                  break;
            case IND_SOURCE:
                  copy_page(dest, addr);
                  dest += PAGE_SIZE;
            }
      }
}

void kexec_copy_flush(struct kimage *image)
{
      long i, nr_segments = image->nr_segments;
      struct  kexec_segment ranges[KEXEC_SEGMENT_MAX];

      /* save the ranges on the stack to efficiently flush the icache */
      memcpy(ranges, image->segment, sizeof(ranges));

      /*
       * After this call we may not use anything allocated in dynamic
       * memory, including *image.
       *
       * Only globals and the stack are allowed.
       */
      copy_segments(image->head);

      /*
       * we need to clear the icache for all dest pages sometime,
       * including ones that were in place on the original copy
       */
      for (i = 0; i < nr_segments; i++)
            flush_icache_range((unsigned long)__va(ranges[i].mem),
                  (unsigned long)__va(ranges[i].mem + ranges[i].memsz));
}

#ifdef CONFIG_SMP

/* FIXME: we should schedule this function to be called on all cpus based
 * on calling the interrupts, but we would like to call it off irq level
 * so that the interrupt controller is clean.
 */
static void kexec_smp_down(void *arg)
{
      if (ppc_md.kexec_cpu_down)
            ppc_md.kexec_cpu_down(0, 1);

      local_irq_disable();
      kexec_smp_wait();
      /* NOTREACHED */
}

static void kexec_prepare_cpus(void)
{
      int my_cpu, i, notified=-1;

      smp_call_function(kexec_smp_down, NULL, /* wait */0);
      my_cpu = get_cpu();

      /* check the others cpus are now down (via paca hw cpu id == -1) */
      for (i=0; i < NR_CPUS; i++) {
            if (i == my_cpu)
                  continue;

            while (paca[i].hw_cpu_id != -1) {
                  barrier();
                  if (!cpu_possible(i)) {
                        printk("kexec: cpu %d hw_cpu_id %d is not"
                                    " possible, ignoring\n",
                                    i, paca[i].hw_cpu_id);
                        break;
                  }
                  if (!cpu_online(i)) {
                        /* Fixme: this can be spinning in
                         * pSeries_secondary_wait with a paca
                         * waiting for it to go online.
                         */
                        printk("kexec: cpu %d hw_cpu_id %d is not"
                                    " online, ignoring\n",
                                    i, paca[i].hw_cpu_id);
                        break;
                  }
                  if (i != notified) {
                        printk( "kexec: waiting for cpu %d (physical"
                                    " %d) to go down\n",
                                    i, paca[i].hw_cpu_id);
                        notified = i;
                  }
            }
      }

      /* after we tell the others to go down */
      if (ppc_md.kexec_cpu_down)
            ppc_md.kexec_cpu_down(0, 0);

      put_cpu();

      local_irq_disable();
}

#else /* ! SMP */

static void kexec_prepare_cpus(void)
{
      /*
       * move the secondarys to us so that we can copy
       * the new kernel 0-0x100 safely
       *
       * do this if kexec in setup.c ?
       *
       * We need to release the cpus if we are ever going from an
       * UP to an SMP kernel.
       */
      smp_release_cpus();
      if (ppc_md.kexec_cpu_down)
            ppc_md.kexec_cpu_down(0, 0);
      local_irq_disable();
}

#endif /* SMP */

/*
 * kexec thread structure and stack.
 *
 * We need to make sure that this is 16384-byte aligned due to the
 * way process stacks are handled.  It also must be statically allocated
 * or allocated as part of the kimage, because everything else may be
 * overwritten when we copy the kexec image.  We piggyback on the
 * "init_task" linker section here to statically allocate a stack.
 *
 * We could use a smaller stack if we don't care about anything using
 * current, but that audit has not been performed.
 */
static union thread_union kexec_stack
      __attribute__((__section__(".data.init_task"))) = { };

/* Our assembly helper, in kexec_stub.S */
extern NORET_TYPE void kexec_sequence(void *newstack, unsigned long start,
                              void *image, void *control,
                              void (*clear_all)(void)) ATTRIB_NORET;

/* too late to fail here */
void default_machine_kexec(struct kimage *image)
{
      /* prepare control code if any */

      /*
        * If the kexec boot is the normal one, need to shutdown other cpus
        * into our wait loop and quiesce interrupts.
        * Otherwise, in the case of crashed mode (crashing_cpu >= 0),
        * stopping other CPUs and collecting their pt_regs is done before
        * using debugger IPI.
        */

      if (crashing_cpu == -1)
            kexec_prepare_cpus();

      /* switch to a staticly allocated stack.  Based on irq stack code.
       * XXX: the task struct will likely be invalid once we do the copy!
       */
      kexec_stack.thread_info.task = current_thread_info()->task;
      kexec_stack.thread_info.flags = 0;

      /* Some things are best done in assembly.  Finding globals with
       * a toc is easier in C, so pass in what we can.
       */
      kexec_sequence(&kexec_stack, image->start, image,
                  page_address(image->control_code_page),
                  ppc_md.hpte_clear_all);
      /* NOTREACHED */
}

/* Values we need to export to the second kernel via the device tree. */
static unsigned long htab_base, kernel_end;

static struct property htab_base_prop = {
      .name = "linux,htab-base",
      .length = sizeof(unsigned long),
      .value = &htab_base,
};

static struct property htab_size_prop = {
      .name = "linux,htab-size",
      .length = sizeof(unsigned long),
      .value = &htab_size_bytes,
};

static struct property kernel_end_prop = {
      .name = "linux,kernel-end",
      .length = sizeof(unsigned long),
      .value = &kernel_end,
};

static void __init export_htab_values(void)
{
      struct device_node *node;
      struct property *prop;

      node = of_find_node_by_path("/chosen");
      if (!node)
            return;

      /* remove any stale propertys so ours can be found */
      prop = of_find_property(node, kernel_end_prop.name, NULL);
      if (prop)
            prom_remove_property(node, prop);
      prop = of_find_property(node, htab_base_prop.name, NULL);
      if (prop)
            prom_remove_property(node, prop);
      prop = of_find_property(node, htab_size_prop.name, NULL);
      if (prop)
            prom_remove_property(node, prop);

      /* information needed by userspace when using default_machine_kexec */
      kernel_end = __pa(_end);
      prom_add_property(node, &kernel_end_prop);

      /* On machines with no htab htab_address is NULL */
      if (NULL == htab_address)
            goto out;

      htab_base = __pa(htab_address);
      prom_add_property(node, &htab_base_prop);
      prom_add_property(node, &htab_size_prop);

 out:
      of_node_put(node);
}

static struct property crashk_base_prop = {
      .name = "linux,crashkernel-base",
      .length = sizeof(unsigned long),
      .value = &crashk_res.start,
};

static unsigned long crashk_size;

static struct property crashk_size_prop = {
      .name = "linux,crashkernel-size",
      .length = sizeof(unsigned long),
      .value = &crashk_size,
};

static void __init export_crashk_values(void)
{
      struct device_node *node;
      struct property *prop;

      node = of_find_node_by_path("/chosen");
      if (!node)
            return;

      /* There might be existing crash kernel properties, but we can't
       * be sure what's in them, so remove them. */
      prop = of_find_property(node, "linux,crashkernel-base", NULL);
      if (prop)
            prom_remove_property(node, prop);

      prop = of_find_property(node, "linux,crashkernel-size", NULL);
      if (prop)
            prom_remove_property(node, prop);

      if (crashk_res.start != 0) {
            prom_add_property(node, &crashk_base_prop);
            crashk_size = crashk_res.end - crashk_res.start + 1;
            prom_add_property(node, &crashk_size_prop);
      }

      of_node_put(node);
}

static int __init kexec_setup(void)
{
      export_htab_values();
      export_crashk_values();
      return 0;
}
__initcall(kexec_setup);

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