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machine_kexec_64.c

/*
 * handle transition of Linux booting another kernel
 * Copyright (C) 2002-2005 Eric Biederman  <ebiederm@xmission.com>
 *
 * This source code is licensed under the GNU General Public License,
 * Version 2.  See the file COPYING for more details.
 */

#include <linux/mm.h>
#include <linux/kexec.h>
#include <linux/string.h>
#include <linux/reboot.h>
#include <linux/numa.h>
#include <asm/pgtable.h>
#include <asm/tlbflush.h>
#include <asm/mmu_context.h>
#include <asm/io.h>

#define PAGE_ALIGNED __attribute__ ((__aligned__(PAGE_SIZE)))
static u64 kexec_pgd[512] PAGE_ALIGNED;
static u64 kexec_pud0[512] PAGE_ALIGNED;
static u64 kexec_pmd0[512] PAGE_ALIGNED;
static u64 kexec_pte0[512] PAGE_ALIGNED;
static u64 kexec_pud1[512] PAGE_ALIGNED;
static u64 kexec_pmd1[512] PAGE_ALIGNED;
static u64 kexec_pte1[512] PAGE_ALIGNED;

static void init_level2_page(pmd_t *level2p, unsigned long addr)
{
      unsigned long end_addr;

      addr &= PAGE_MASK;
      end_addr = addr + PUD_SIZE;
      while (addr < end_addr) {
            set_pmd(level2p++, __pmd(addr | __PAGE_KERNEL_LARGE_EXEC));
            addr += PMD_SIZE;
      }
}

static int init_level3_page(struct kimage *image, pud_t *level3p,
                        unsigned long addr, unsigned long last_addr)
{
      unsigned long end_addr;
      int result;

      result = 0;
      addr &= PAGE_MASK;
      end_addr = addr + PGDIR_SIZE;
      while ((addr < last_addr) && (addr < end_addr)) {
            struct page *page;
            pmd_t *level2p;

            page = kimage_alloc_control_pages(image, 0);
            if (!page) {
                  result = -ENOMEM;
                  goto out;
            }
            level2p = (pmd_t *)page_address(page);
            init_level2_page(level2p, addr);
            set_pud(level3p++, __pud(__pa(level2p) | _KERNPG_TABLE));
            addr += PUD_SIZE;
      }
      /* clear the unused entries */
      while (addr < end_addr) {
            pud_clear(level3p++);
            addr += PUD_SIZE;
      }
out:
      return result;
}


static int init_level4_page(struct kimage *image, pgd_t *level4p,
                        unsigned long addr, unsigned long last_addr)
{
      unsigned long end_addr;
      int result;

      result = 0;
      addr &= PAGE_MASK;
      end_addr = addr + (PTRS_PER_PGD * PGDIR_SIZE);
      while ((addr < last_addr) && (addr < end_addr)) {
            struct page *page;
            pud_t *level3p;

            page = kimage_alloc_control_pages(image, 0);
            if (!page) {
                  result = -ENOMEM;
                  goto out;
            }
            level3p = (pud_t *)page_address(page);
            result = init_level3_page(image, level3p, addr, last_addr);
            if (result) {
                  goto out;
            }
            set_pgd(level4p++, __pgd(__pa(level3p) | _KERNPG_TABLE));
            addr += PGDIR_SIZE;
      }
      /* clear the unused entries */
      while (addr < end_addr) {
            pgd_clear(level4p++);
            addr += PGDIR_SIZE;
      }
out:
      return result;
}


static int init_pgtable(struct kimage *image, unsigned long start_pgtable)
{
      pgd_t *level4p;
      level4p = (pgd_t *)__va(start_pgtable);
      return init_level4_page(image, level4p, 0, end_pfn << PAGE_SHIFT);
}

static void set_idt(void *newidt, u16 limit)
{
      struct desc_ptr curidt;

      /* x86-64 supports unaliged loads & stores */
      curidt.size    = limit;
      curidt.address = (unsigned long)newidt;

      __asm__ __volatile__ (
            "lidtq %0\n"
            : : "m" (curidt)
            );
};


static void set_gdt(void *newgdt, u16 limit)
{
      struct desc_ptr curgdt;

      /* x86-64 supports unaligned loads & stores */
      curgdt.size    = limit;
      curgdt.address = (unsigned long)newgdt;

      __asm__ __volatile__ (
            "lgdtq %0\n"
            : : "m" (curgdt)
            );
};

static void load_segments(void)
{
      __asm__ __volatile__ (
            "\tmovl %0,%%ds\n"
            "\tmovl %0,%%es\n"
            "\tmovl %0,%%ss\n"
            "\tmovl %0,%%fs\n"
            "\tmovl %0,%%gs\n"
            : : "a" (__KERNEL_DS) : "memory"
            );
}

int machine_kexec_prepare(struct kimage *image)
{
      unsigned long start_pgtable;
      int result;

      /* Calculate the offsets */
      start_pgtable = page_to_pfn(image->control_code_page) << PAGE_SHIFT;

      /* Setup the identity mapped 64bit page table */
      result = init_pgtable(image, start_pgtable);
      if (result)
            return result;

      return 0;
}

void machine_kexec_cleanup(struct kimage *image)
{
      return;
}

/*
 * Do not allocate memory (or fail in any way) in machine_kexec().
 * We are past the point of no return, committed to rebooting now.
 */
NORET_TYPE void machine_kexec(struct kimage *image)
{
      unsigned long page_list[PAGES_NR];
      void *control_page;

      /* Interrupts aren't acceptable while we reboot */
      local_irq_disable();

      control_page = page_address(image->control_code_page) + PAGE_SIZE;
      memcpy(control_page, relocate_kernel, PAGE_SIZE);

      page_list[PA_CONTROL_PAGE] = virt_to_phys(control_page);
      page_list[VA_CONTROL_PAGE] = (unsigned long)relocate_kernel;
      page_list[PA_PGD] = virt_to_phys(&kexec_pgd);
      page_list[VA_PGD] = (unsigned long)kexec_pgd;
      page_list[PA_PUD_0] = virt_to_phys(&kexec_pud0);
      page_list[VA_PUD_0] = (unsigned long)kexec_pud0;
      page_list[PA_PMD_0] = virt_to_phys(&kexec_pmd0);
      page_list[VA_PMD_0] = (unsigned long)kexec_pmd0;
      page_list[PA_PTE_0] = virt_to_phys(&kexec_pte0);
      page_list[VA_PTE_0] = (unsigned long)kexec_pte0;
      page_list[PA_PUD_1] = virt_to_phys(&kexec_pud1);
      page_list[VA_PUD_1] = (unsigned long)kexec_pud1;
      page_list[PA_PMD_1] = virt_to_phys(&kexec_pmd1);
      page_list[VA_PMD_1] = (unsigned long)kexec_pmd1;
      page_list[PA_PTE_1] = virt_to_phys(&kexec_pte1);
      page_list[VA_PTE_1] = (unsigned long)kexec_pte1;

      page_list[PA_TABLE_PAGE] =
        (unsigned long)__pa(page_address(image->control_code_page));

      /* The segment registers are funny things, they have both a
       * visible and an invisible part.  Whenever the visible part is
       * set to a specific selector, the invisible part is loaded
       * with from a table in memory.  At no other time is the
       * descriptor table in memory accessed.
       *
       * I take advantage of this here by force loading the
       * segments, before I zap the gdt with an invalid value.
       */
      load_segments();
      /* The gdt & idt are now invalid.
       * If you want to load them you must set up your own idt & gdt.
       */
      set_gdt(phys_to_virt(0),0);
      set_idt(phys_to_virt(0),0);

      /* now call it */
      relocate_kernel((unsigned long)image->head, (unsigned long)page_list,
                  image->start);
}

void arch_crash_save_vmcoreinfo(void)
{
      VMCOREINFO_SYMBOL(init_level4_pgt);

#ifdef CONFIG_ARCH_DISCONTIGMEM_ENABLE
      VMCOREINFO_SYMBOL(node_data);
      VMCOREINFO_LENGTH(node_data, MAX_NUMNODES);
#endif
}


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