text: /*
   * 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/delay.h>
  #include <linux/numa.h>
  #include <linux/ftrace.h>
  #include <linux/suspend.h>
  #include <linux/gfp.h>
  #include <linux/io.h>
  
  #include <asm/pgtable.h>
  #include <asm/pgalloc.h>
  #include <asm/tlbflush.h>
  #include <asm/mmu_context.h>
  #include <asm/apic.h>
  #include <asm/io_apic.h>
  #include <asm/cpufeature.h>
  #include <asm/desc.h>
  #include <asm/set_memory.h>
  #include <asm/debugreg.h>
  
  static void set_gdt(void *newgdt, __u16 limit)
  {
  	struct desc_ptr curgdt;
  
  	/* ia32 supports unaligned loads & stores */
  	curgdt.size    = limit;
  	curgdt.address = (unsigned long)newgdt;
  
  	load_gdt(&curgdt);
  }
  
  static void load_segments(void)
  {
  #define __STR(X) #X
  #define STR(X) __STR(X)
  
  	__asm__ __volatile__ (
  		"\tljmp $"STR(__KERNEL_CS)",$1f\n"
  		"\t1:\n"
  		"\tmovl $"STR(__KERNEL_DS)",%%eax\n"
  		"\tmovl %%eax,%%ds\n"
  		"\tmovl %%eax,%%es\n"
  		"\tmovl %%eax,%%ss\n"
  		: : : "eax", "memory");
  #undef STR
  #undef __STR
  }
  
  static void machine_kexec_free_page_tables(struct kimage *image)
  {
  	free_page((unsigned long)image->arch.pgd);
  	image->arch.pgd = NULL;
  #ifdef CONFIG_X86_PAE
  	free_page((unsigned long)image->arch.pmd0);
  	image->arch.pmd0 = NULL;
  	free_page((unsigned long)image->arch.pmd1);
  	image->arch.pmd1 = NULL;
  #endif
  	free_page((unsigned long)image->arch.pte0);
  	image->arch.pte0 = NULL;
  	free_page((unsigned long)image->arch.pte1);
  	image->arch.pte1 = NULL;
  }
  
  static int machine_kexec_alloc_page_tables(struct kimage *image)
  {
  	image->arch.pgd = (pgd_t *)get_zeroed_page(GFP_KERNEL);
  #ifdef CONFIG_X86_PAE
  	image->arch.pmd0 = (pmd_t *)get_zeroed_page(GFP_KERNEL);
  	image->arch.pmd1 = (pmd_t *)get_zeroed_page(GFP_KERNEL);
  #endif
  	image->arch.pte0 = (pte_t *)get_zeroed_page(GFP_KERNEL);
  	image->arch.pte1 = (pte_t *)get_zeroed_page(GFP_KERNEL);
  	if (!image->arch.pgd ||
  #ifdef CONFIG_X86_PAE
  	    !image->arch.pmd0 || !image->arch.pmd1 ||
  #endif
  	    !image->arch.pte0 || !image->arch.pte1) {
  		return -ENOMEM;
  	}
  	return 0;
  }
  
  static void machine_kexec_page_table_set_one(
  	pgd_t *pgd, pmd_t *pmd, pte_t *pte,
  	unsigned long vaddr, unsigned long paddr)
  {
  	p4d_t *p4d;
  	pud_t *pud;
  
  	pgd += pgd_index(vaddr);
  #ifdef CONFIG_X86_PAE
  	if (!(pgd_val(*pgd) & _PAGE_PRESENT))
  		set_pgd(pgd, __pgd(__pa(pmd) | _PAGE_PRESENT));
  #endif
  	p4d = p4d_offset(pgd, vaddr);
  	pud = pud_offset(p4d, vaddr);
  	pmd = pmd_offset(pud, vaddr);
  	if (!(pmd_val(*pmd) & _PAGE_PRESENT))
  		set_pmd(pmd, __pmd(__pa(pte) | _PAGE_TABLE));
  	pte = pte_offset_kernel(pmd, vaddr);
  	set_pte(pte, pfn_pte(paddr >> PAGE_SHIFT, PAGE_KERNEL_EXEC));
  }
  
  static void machine_kexec_prepare_page_tables(struct kimage *image)
  {
  	void *control_page;
  	pmd_t *pmd = NULL;
  
  	control_page = page_address(image->control_code_page);
  #ifdef CONFIG_X86_PAE
  	pmd = image->arch.pmd0;
  #endif
  	machine_kexec_page_table_set_one(
  		image->arch.pgd, pmd, image->arch.pte0,
  		(unsigned long)control_page, __pa(control_page));
  #ifdef CONFIG_X86_PAE
  	pmd = image->arch.pmd1;
  #endif
  	machine_kexec_page_table_set_one(
  		image->arch.pgd, pmd, image->arch.pte1,
  		__pa(control_page), __pa(control_page));
  }
  
  /*
   * A architecture hook called to validate the
   * proposed image and prepare the control pages
   * as needed.  The pages for KEXEC_CONTROL_PAGE_SIZE
   * have been allocated, but the segments have yet
   * been copied into the kernel.
   *
   * Do what every setup is needed on image and the
   * reboot code buffer to allow us to avoid allocations
   * later.
   *
   * - Make control page executable.
   * - Allocate page tables
   * - Setup page tables
   */
  int machine_kexec_prepare(struct kimage *image)
  {
  	int error;
  
  	set_pages_x(image->control_code_page, 1);
  	error = machine_kexec_alloc_page_tables(image);
  	if (error)
  		return error;
  	machine_kexec_prepare_page_tables(image);
  	return 0;
  }
  
  /*
   * Undo anything leftover by machine_kexec_prepare
   * when an image is freed.
   */
  void machine_kexec_cleanup(struct kimage *image)
  {
  	set_pages_nx(image->control_code_page, 1);
  	machine_kexec_free_page_tables(image);
  }
  
  /*
   * Do not allocate memory (or fail in any way) in machine_kexec().
   * We are past the point of no return, committed to rebooting now.
   */
  void machine_kexec(struct kimage *image)
  {
  	unsigned long page_list[PAGES_NR];
  	void *control_page;
  	int save_ftrace_enabled;
  	asmlinkage unsigned long
  		(*relocate_kernel_ptr)(unsigned long indirection_page,
  				       unsigned long control_page,
  				       unsigned long start_address,
  				       unsigned int has_pae,
  				       unsigned int preserve_context);
  
  #ifdef CONFIG_KEXEC_JUMP
  	if (image->preserve_context)
  		save_processor_state();
  #endif
  
  	save_ftrace_enabled = __ftrace_enabled_save();
  
  	/* Interrupts aren't acceptable while we reboot */
  	local_irq_disable();
  	hw_breakpoint_disable();
  
  	if (image->preserve_context) {
  #ifdef CONFIG_X86_IO_APIC
  		/*
  		 * We need to put APICs in legacy mode so that we can
  		 * get timer interrupts in second kernel. kexec/kdump
  		 * paths already have calls to restore_boot_irq_mode()
  		 * in one form or other. kexec jump path also need one.
  		 */
  		clear_IO_APIC();
  		restore_boot_irq_mode();
  #endif
  	}
  
  	control_page = page_address(image->control_code_page);
  	memcpy(control_page, relocate_kernel, KEXEC_CONTROL_CODE_MAX_SIZE);
  
  	relocate_kernel_ptr = control_page;
  	page_list[PA_CONTROL_PAGE] = __pa(control_page);
  	page_list[VA_CONTROL_PAGE] = (unsigned long)control_page;
  	page_list[PA_PGD] = __pa(image->arch.pgd);
  
  	if (image->type == KEXEC_TYPE_DEFAULT)
  		page_list[PA_SWAP_PAGE] = (page_to_pfn(image->swap_page)
  						<< PAGE_SHIFT);
  
  	/*
  	 * 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.
  	 */
  	idt_invalidate(phys_to_virt(0));
  	set_gdt(phys_to_virt(0), 0);
  
  	/* now call it */
  	image->start = relocate_kernel_ptr((unsigned long)image->head,
  					   (unsigned long)page_list,
  					   image->start,
  					   boot_cpu_has(X86_FEATURE_PAE),
  					   image->preserve_context);
  
  #ifdef CONFIG_KEXEC_JUMP
  	if (image->preserve_context)
  		restore_processor_state();
  #endif
  
  	__ftrace_enabled_restore(save_ftrace_enabled);
  }
  
  void arch_crash_save_vmcoreinfo(void)
  {
  #ifdef CONFIG_NUMA
  	VMCOREINFO_SYMBOL(node_data);
  	VMCOREINFO_LENGTH(node_data, MAX_NUMNODES);
  #endif
  #ifdef CONFIG_X86_PAE
  	VMCOREINFO_CONFIG(X86_PAE);
  #endif
  }
  
  