arch/x86/kernel/crash.c - arm/linux - Git at Google

 /*
  * Architecture specific (i386/x86_64) functions for kexec based crash dumps.
  *
  * Created by: Hariprasad Nellitheertha (hari@in.ibm.com)
  *
  * Copyright (C) IBM Corporation, 2004. All rights reserved.
  * Copyright (C) Red Hat Inc., 2014. All rights reserved.
  * Authors:
  *      Vivek Goyal <vgoyal@redhat.com>
  *
  */

 #define pr_fmt(fmt)	"kexec: " fmt

 #include <linux/types.h>
 #include <linux/kernel.h>
 #include <linux/smp.h>
 #include <linux/reboot.h>
 #include <linux/kexec.h>
 #include <linux/delay.h>
 #include <linux/elf.h>
 #include <linux/elfcore.h>
 #include <linux/export.h>
 #include <linux/slab.h>
 #include <linux/vmalloc.h>

 #include <asm/processor.h>
 #include <asm/hardirq.h>
 #include <asm/nmi.h>
 #include <asm/hw_irq.h>
 #include <asm/apic.h>
 #include <asm/io_apic.h>
 #include <asm/hpet.h>
 #include <linux/kdebug.h>
 #include <asm/cpu.h>
 #include <asm/reboot.h>
 #include <asm/virtext.h>
 #include <asm/intel_pt.h>

 /* Alignment required for elf header segment */
 #define ELF_CORE_HEADER_ALIGN   4096

 /* This primarily represents number of split ranges due to exclusion */
 #define CRASH_MAX_RANGES	16

 struct crash_mem_range {
 	u64 start, end;
 };

 struct crash_mem {
 	unsigned int nr_ranges;
 	struct crash_mem_range ranges[CRASH_MAX_RANGES];
 };

 /* Misc data about ram ranges needed to prepare elf headers */
 struct crash_elf_data {
 	struct kimage *image;
 	/*
 	 * Total number of ram ranges we have after various adjustments for
 	 * crash reserved region, etc.
 	 */
 	unsigned int max_nr_ranges;

 	/* Pointer to elf header */
 	void *ehdr;
 	/* Pointer to next phdr */
 	void *bufp;
 	struct crash_mem mem;
 };

 /* Used while preparing memory map entries for second kernel */
 struct crash_memmap_data {
 	struct boot_params *params;
 	/* Type of memory */
 	unsigned int type;
 };

 /*
  * This is used to VMCLEAR all VMCSs loaded on the
  * processor. And when loading kvm_intel module, the
  * callback function pointer will be assigned.
  *
  * protected by rcu.
  */
 crash_vmclear_fn __rcu *crash_vmclear_loaded_vmcss = NULL;
 EXPORT_SYMBOL_GPL(crash_vmclear_loaded_vmcss);
 unsigned long crash_zero_bytes;

 static inline void cpu_crash_vmclear_loaded_vmcss(void)
 {
 	crash_vmclear_fn *do_vmclear_operation = NULL;

 	rcu_read_lock();
 	do_vmclear_operation = rcu_dereference(crash_vmclear_loaded_vmcss);
 	if (do_vmclear_operation)
 		do_vmclear_operation();
 	rcu_read_unlock();
 }

 #if defined(CONFIG_SMP) && defined(CONFIG_X86_LOCAL_APIC)

 static void kdump_nmi_callback(int cpu, struct pt_regs *regs)
 {
 #ifdef CONFIG_X86_32
 	struct pt_regs fixed_regs;

 	if (!user_mode(regs)) {
 		crash_fixup_ss_esp(&fixed_regs, regs);
 		regs = &fixed_regs;
 	}
 #endif
 	crash_save_cpu(regs, cpu);

 	/*
 	 * VMCLEAR VMCSs loaded on all cpus if needed.
 	 */
 	cpu_crash_vmclear_loaded_vmcss();

 	/* Disable VMX or SVM if needed.
 	 *
 	 * We need to disable virtualization on all CPUs.
 	 * Having VMX or SVM enabled on any CPU may break rebooting
 	 * after the kdump kernel has finished its task.
 	 */
 	cpu_emergency_vmxoff();
 	cpu_emergency_svm_disable();

 	/*
 	 * Disable Intel PT to stop its logging
 	 */
 	cpu_emergency_stop_pt();

 	disable_local_APIC();
 }

 static void kdump_nmi_shootdown_cpus(void)
 {
 	nmi_shootdown_cpus(kdump_nmi_callback);

 	disable_local_APIC();
 }

 #else
 static void kdump_nmi_shootdown_cpus(void)
 {
 	/* There are no cpus to shootdown */
 }
 #endif

 void native_machine_crash_shutdown(struct pt_regs *regs)
 {
 	/* This function is only called after the system
 	 * has panicked or is otherwise in a critical state.
 	 * The minimum amount of code to allow a kexec'd kernel
 	 * to run successfully needs to happen here.
 	 *
 	 * In practice this means shooting down the other cpus in
 	 * an SMP system.
 	 */
 	/* The kernel is broken so disable interrupts */
 	local_irq_disable();

 	kdump_nmi_shootdown_cpus();

 	/*
 	 * VMCLEAR VMCSs loaded on this cpu if needed.
 	 */
 	cpu_crash_vmclear_loaded_vmcss();

 	/* Booting kdump kernel with VMX or SVM enabled won't work,
 	 * because (among other limitations) we can't disable paging
 	 * with the virt flags.
 	 */
 	cpu_emergency_vmxoff();
 	cpu_emergency_svm_disable();

 	/*
 	 * Disable Intel PT to stop its logging
 	 */
 	cpu_emergency_stop_pt();

 #ifdef CONFIG_X86_IO_APIC
 	/* Prevent crash_kexec() from deadlocking on ioapic_lock. */
 	ioapic_zap_locks();
 	disable_IO_APIC();
 #endif
 	lapic_shutdown();
 #ifdef CONFIG_HPET_TIMER
 	hpet_disable();
 #endif
 	crash_save_cpu(regs, safe_smp_processor_id());
 }

 #ifdef CONFIG_KEXEC_FILE
 static int get_nr_ram_ranges_callback(u64 start, u64 end, void *arg)
 {
 	unsigned int *nr_ranges = arg;

 	(*nr_ranges)++;
 	return 0;
 }


 /* Gather all the required information to prepare elf headers for ram regions */
 static void fill_up_crash_elf_data(struct crash_elf_data *ced,
 				   struct kimage *image)
 {
 	unsigned int nr_ranges = 0;

 	ced->image = image;

 	walk_system_ram_res(0, -1, &nr_ranges,
 				get_nr_ram_ranges_callback);

 	ced->max_nr_ranges = nr_ranges;

 	/* Exclusion of crash region could split memory ranges */
 	ced->max_nr_ranges++;

 	/* If crashk_low_res is not 0, another range split possible */
 	if (crashk_low_res.end)
 		ced->max_nr_ranges++;
 }

 static int exclude_mem_range(struct crash_mem *mem,
 		unsigned long long mstart, unsigned long long mend)
 {
 	int i, j;
 	unsigned long long start, end;
 	struct crash_mem_range temp_range = {0, 0};

 	for (i = 0; i < mem->nr_ranges; i++) {
 		start = mem->ranges[i].start;
 		end = mem->ranges[i].end;

 		if (mstart > end || mend < start)
 			continue;

 		/* Truncate any area outside of range */
 		if (mstart < start)
 			mstart = start;
 		if (mend > end)
 			mend = end;

 		/* Found completely overlapping range */
 		if (mstart == start && mend == end) {
 			mem->ranges[i].start = 0;
 			mem->ranges[i].end = 0;
 			if (i < mem->nr_ranges - 1) {
 				/* Shift rest of the ranges to left */
 				for (j = i; j < mem->nr_ranges - 1; j++) {
 					mem->ranges[j].start =
 						mem->ranges[j+1].start;
 					mem->ranges[j].end =
 							mem->ranges[j+1].end;
 				}
 			}
 			mem->nr_ranges--;
 			return 0;
 		}

 		if (mstart > start && mend < end) {
 			/* Split original range */
 			mem->ranges[i].end = mstart - 1;
 			temp_range.start = mend + 1;
 			temp_range.end = end;
 		} else if (mstart != start)
 			mem->ranges[i].end = mstart - 1;
 		else
 			mem->ranges[i].start = mend + 1;
 		break;
 	}

 	/* If a split happend, add the split to array */
 	if (!temp_range.end)
 		return 0;

 	/* Split happened */
 	if (i == CRASH_MAX_RANGES - 1) {
 		pr_err("Too many crash ranges after split\n");
 		return -ENOMEM;
 	}

 	/* Location where new range should go */
 	j = i + 1;
 	if (j < mem->nr_ranges) {
 		/* Move over all ranges one slot towards the end */
 		for (i = mem->nr_ranges - 1; i >= j; i--)
 			mem->ranges[i + 1] = mem->ranges[i];
 	}

 	mem->ranges[j].start = temp_range.start;
 	mem->ranges[j].end = temp_range.end;
 	mem->nr_ranges++;
 	return 0;
 }

 /*
  * Look for any unwanted ranges between mstart, mend and remove them. This
  * might lead to split and split ranges are put in ced->mem.ranges[] array
  */
 static int elf_header_exclude_ranges(struct crash_elf_data *ced,
 		unsigned long long mstart, unsigned long long mend)
 {
 	struct crash_mem *cmem = &ced->mem;
 	int ret = 0;

 	memset(cmem->ranges, 0, sizeof(cmem->ranges));

 	cmem->ranges[0].start = mstart;
 	cmem->ranges[0].end = mend;
 	cmem->nr_ranges = 1;

 	/* Exclude crashkernel region */
 	ret = exclude_mem_range(cmem, crashk_res.start, crashk_res.end);
 	if (ret)
 		return ret;

 	if (crashk_low_res.end) {
 		ret = exclude_mem_range(cmem, crashk_low_res.start, crashk_low_res.end);
 		if (ret)
 			return ret;
 	}

 	return ret;
 }

 static int prepare_elf64_ram_headers_callback(u64 start, u64 end, void *arg)
 {
 	struct crash_elf_data *ced = arg;
 	Elf64_Ehdr *ehdr;
 	Elf64_Phdr *phdr;
 	unsigned long mstart, mend;
 	struct kimage *image = ced->image;
 	struct crash_mem *cmem;
 	int ret, i;

 	ehdr = ced->ehdr;

 	/* Exclude unwanted mem ranges */
 	ret = elf_header_exclude_ranges(ced, start, end);
 	if (ret)
 		return ret;

 	/* Go through all the ranges in ced->mem.ranges[] and prepare phdr */
 	cmem = &ced->mem;

 	for (i = 0; i < cmem->nr_ranges; i++) {
 		mstart = cmem->ranges[i].start;
 		mend = cmem->ranges[i].end;

 		phdr = ced->bufp;
 		ced->bufp += sizeof(Elf64_Phdr);

 		phdr->p_type = PT_LOAD;
 		phdr->p_flags = PF_R|PF_W|PF_X;
 		phdr->p_offset  = mstart;

 		/*
 		 * If a range matches backup region, adjust offset to backup
 		 * segment.
 		 */
 		if (mstart == image->arch.backup_src_start &&
 		    (mend - mstart + 1) == image->arch.backup_src_sz)
 			phdr->p_offset = image->arch.backup_load_addr;

 		phdr->p_paddr = mstart;
 		phdr->p_vaddr = (unsigned long long) __va(mstart);
 		phdr->p_filesz = phdr->p_memsz = mend - mstart + 1;
 		phdr->p_align = 0;
 		ehdr->e_phnum++;
 		pr_debug("Crash PT_LOAD elf header. phdr=%p vaddr=0x%llx, paddr=0x%llx, sz=0x%llx e_phnum=%d p_offset=0x%llx\n",
 			phdr, phdr->p_vaddr, phdr->p_paddr, phdr->p_filesz,
 			ehdr->e_phnum, phdr->p_offset);
 	}

 	return ret;
 }

 static int prepare_elf64_headers(struct crash_elf_data *ced,
 		void **addr, unsigned long *sz)
 {
 	Elf64_Ehdr *ehdr;
 	Elf64_Phdr *phdr;
 	unsigned long nr_cpus = num_possible_cpus(), nr_phdr, elf_sz;
 	unsigned char *buf, *bufp;
 	unsigned int cpu;
 	unsigned long long notes_addr;
 	int ret;

 	/* extra phdr for vmcoreinfo elf note */
 	nr_phdr = nr_cpus + 1;
 	nr_phdr += ced->max_nr_ranges;

 	/*
 	 * kexec-tools creates an extra PT_LOAD phdr for kernel text mapping
 	 * area on x86_64 (ffffffff80000000 - ffffffffa0000000).
 	 * I think this is required by tools like gdb. So same physical
 	 * memory will be mapped in two elf headers. One will contain kernel
 	 * text virtual addresses and other will have __va(physical) addresses.
 	 */

 	nr_phdr++;
 	elf_sz = sizeof(Elf64_Ehdr) + nr_phdr * sizeof(Elf64_Phdr);
 	elf_sz = ALIGN(elf_sz, ELF_CORE_HEADER_ALIGN);

 	buf = vzalloc(elf_sz);
 	if (!buf)
 		return -ENOMEM;

 	bufp = buf;
 	ehdr = (Elf64_Ehdr *)bufp;
 	bufp += sizeof(Elf64_Ehdr);
 	memcpy(ehdr->e_ident, ELFMAG, SELFMAG);
 	ehdr->e_ident[EI_CLASS] = ELFCLASS64;
 	ehdr->e_ident[EI_DATA] = ELFDATA2LSB;
 	ehdr->e_ident[EI_VERSION] = EV_CURRENT;
 	ehdr->e_ident[EI_OSABI] = ELF_OSABI;
 	memset(ehdr->e_ident + EI_PAD, 0, EI_NIDENT - EI_PAD);
 	ehdr->e_type = ET_CORE;
 	ehdr->e_machine = ELF_ARCH;
 	ehdr->e_version = EV_CURRENT;
 	ehdr->e_phoff = sizeof(Elf64_Ehdr);
 	ehdr->e_ehsize = sizeof(Elf64_Ehdr);
 	ehdr->e_phentsize = sizeof(Elf64_Phdr);

 	/* Prepare one phdr of type PT_NOTE for each present cpu */
 	for_each_present_cpu(cpu) {
 		phdr = (Elf64_Phdr *)bufp;
 		bufp += sizeof(Elf64_Phdr);
 		phdr->p_type = PT_NOTE;
 		notes_addr = per_cpu_ptr_to_phys(per_cpu_ptr(crash_notes, cpu));
 		phdr->p_offset = phdr->p_paddr = notes_addr;
 		phdr->p_filesz = phdr->p_memsz = sizeof(note_buf_t);
 		(ehdr->e_phnum)++;
 	}

 	/* Prepare one PT_NOTE header for vmcoreinfo */
 	phdr = (Elf64_Phdr *)bufp;
 	bufp += sizeof(Elf64_Phdr);
 	phdr->p_type = PT_NOTE;
 	phdr->p_offset = phdr->p_paddr = paddr_vmcoreinfo_note();
 	phdr->p_filesz = phdr->p_memsz = sizeof(vmcoreinfo_note);
 	(ehdr->e_phnum)++;

 #ifdef CONFIG_X86_64
 	/* Prepare PT_LOAD type program header for kernel text region */
 	phdr = (Elf64_Phdr *)bufp;
 	bufp += sizeof(Elf64_Phdr);
 	phdr->p_type = PT_LOAD;
 	phdr->p_flags = PF_R|PF_W|PF_X;
 	phdr->p_vaddr = (Elf64_Addr)_text;
 	phdr->p_filesz = phdr->p_memsz = _end - _text;
 	phdr->p_offset = phdr->p_paddr = __pa_symbol(_text);
 	(ehdr->e_phnum)++;
 #endif

 	/* Prepare PT_LOAD headers for system ram chunks. */
 	ced->ehdr = ehdr;
 	ced->bufp = bufp;
 	ret = walk_system_ram_res(0, -1, ced,
 			prepare_elf64_ram_headers_callback);
 	if (ret < 0)
 		return ret;

 	*addr = buf;
 	*sz = elf_sz;
 	return 0;
 }

 /* Prepare elf headers. Return addr and size */
 static int prepare_elf_headers(struct kimage *image, void **addr,
 					unsigned long *sz)
 {
 	struct crash_elf_data *ced;
 	int ret;

 	ced = kzalloc(sizeof(*ced), GFP_KERNEL);
 	if (!ced)
 		return -ENOMEM;

 	fill_up_crash_elf_data(ced, image);

 	/* By default prepare 64bit headers */
 	ret =  prepare_elf64_headers(ced, addr, sz);
 	kfree(ced);
 	return ret;
 }

 static int add_e820_entry(struct boot_params *params, struct e820entry *entry)
 {
 	unsigned int nr_e820_entries;

 	nr_e820_entries = params->e820_entries;
 	if (nr_e820_entries >= E820MAX)
 		return 1;

 	memcpy(&params->e820_map[nr_e820_entries], entry,
 			sizeof(struct e820entry));
 	params->e820_entries++;
 	return 0;
 }

 static int memmap_entry_callback(u64 start, u64 end, void *arg)
 {
 	struct crash_memmap_data *cmd = arg;
 	struct boot_params *params = cmd->params;
 	struct e820entry ei;

 	ei.addr = start;
 	ei.size = end - start + 1;
 	ei.type = cmd->type;
 	add_e820_entry(params, &ei);

 	return 0;
 }

 static int memmap_exclude_ranges(struct kimage *image, struct crash_mem *cmem,
 				 unsigned long long mstart,
 				 unsigned long long mend)
 {
 	unsigned long start, end;
 	int ret = 0;

 	cmem->ranges[0].start = mstart;
 	cmem->ranges[0].end = mend;
 	cmem->nr_ranges = 1;

 	/* Exclude Backup region */
 	start = image->arch.backup_load_addr;
 	end = start + image->arch.backup_src_sz - 1;
 	ret = exclude_mem_range(cmem, start, end);
 	if (ret)
 		return ret;

 	/* Exclude elf header region */
 	start = image->arch.elf_load_addr;
 	end = start + image->arch.elf_headers_sz - 1;
 	return exclude_mem_range(cmem, start, end);
 }

 /* Prepare memory map for crash dump kernel */
 int crash_setup_memmap_entries(struct kimage *image, struct boot_params *params)
 {
 	int i, ret = 0;
 	unsigned long flags;
 	struct e820entry ei;
 	struct crash_memmap_data cmd;
 	struct crash_mem *cmem;

 	cmem = vzalloc(sizeof(struct crash_mem));
 	if (!cmem)
 		return -ENOMEM;

 	memset(&cmd, 0, sizeof(struct crash_memmap_data));
 	cmd.params = params;

 	/* Add first 640K segment */
 	ei.addr = image->arch.backup_src_start;
 	ei.size = image->arch.backup_src_sz;
 	ei.type = E820_RAM;
 	add_e820_entry(params, &ei);

 	/* Add ACPI tables */
 	cmd.type = E820_ACPI;
 	flags = IORESOURCE_MEM | IORESOURCE_BUSY;
 	walk_iomem_res_desc(IORES_DESC_ACPI_TABLES, flags, 0, -1, &cmd,
 		       memmap_entry_callback);

 	/* Add ACPI Non-volatile Storage */
 	cmd.type = E820_NVS;
 	walk_iomem_res_desc(IORES_DESC_ACPI_NV_STORAGE, flags, 0, -1, &cmd,
 			memmap_entry_callback);

 	/* Add crashk_low_res region */
 	if (crashk_low_res.end) {
 		ei.addr = crashk_low_res.start;
 		ei.size = crashk_low_res.end - crashk_low_res.start + 1;
 		ei.type = E820_RAM;
 		add_e820_entry(params, &ei);
 	}

 	/* Exclude some ranges from crashk_res and add rest to memmap */
 	ret = memmap_exclude_ranges(image, cmem, crashk_res.start,
 						crashk_res.end);
 	if (ret)
 		goto out;

 	for (i = 0; i < cmem->nr_ranges; i++) {
 		ei.size = cmem->ranges[i].end - cmem->ranges[i].start + 1;

 		/* If entry is less than a page, skip it */
 		if (ei.size < PAGE_SIZE)
 			continue;
 		ei.addr = cmem->ranges[i].start;
 		ei.type = E820_RAM;
 		add_e820_entry(params, &ei);
 	}

 out:
 	vfree(cmem);
 	return ret;
 }

 static int determine_backup_region(u64 start, u64 end, void *arg)
 {
 	struct kimage *image = arg;

 	image->arch.backup_src_start = start;
 	image->arch.backup_src_sz = end - start + 1;

 	/* Expecting only one range for backup region */
 	return 1;
 }

 int crash_load_segments(struct kimage *image)
 {
 	unsigned long src_start, src_sz, elf_sz;
 	void *elf_addr;
 	int ret;

 	/*
 	 * Determine and load a segment for backup area. First 640K RAM
 	 * region is backup source
 	 */

 	ret = walk_system_ram_res(KEXEC_BACKUP_SRC_START, KEXEC_BACKUP_SRC_END,
 				image, determine_backup_region);

 	/* Zero or postive return values are ok */
 	if (ret < 0)
 		return ret;

 	src_start = image->arch.backup_src_start;
 	src_sz = image->arch.backup_src_sz;

 	/* Add backup segment. */
 	if (src_sz) {
 		/*
 		 * Ideally there is no source for backup segment. This is
 		 * copied in purgatory after crash. Just add a zero filled
 		 * segment for now to make sure checksum logic works fine.
 		 */
 		ret = kexec_add_buffer(image, (char *)&crash_zero_bytes,
 				       sizeof(crash_zero_bytes), src_sz,
 				       PAGE_SIZE, 0, -1, 0,
 				       &image->arch.backup_load_addr);
 		if (ret)
 			return ret;
 		pr_debug("Loaded backup region at 0x%lx backup_start=0x%lx memsz=0x%lx\n",
 			 image->arch.backup_load_addr, src_start, src_sz);
 	}

 	/* Prepare elf headers and add a segment */
 	ret = prepare_elf_headers(image, &elf_addr, &elf_sz);
 	if (ret)
 		return ret;

 	image->arch.elf_headers = elf_addr;
 	image->arch.elf_headers_sz = elf_sz;

 	ret = kexec_add_buffer(image, (char *)elf_addr, elf_sz, elf_sz,
 			ELF_CORE_HEADER_ALIGN, 0, -1, 0,
 			&image->arch.elf_load_addr);
 	if (ret) {
 		vfree((void *)image->arch.elf_headers);
 		return ret;
 	}
 	pr_debug("Loaded ELF headers at 0x%lx bufsz=0x%lx memsz=0x%lx\n",
 		 image->arch.elf_load_addr, elf_sz, elf_sz);

 	return ret;
 }
 #endif /* CONFIG_KEXEC_FILE */
	/*
	* Architecture specific (i386/x86_64) functions for kexec based crash dumps.
	*
	* Created by: Hariprasad Nellitheertha (hari@in.ibm.com)
	*
	* Copyright (C) IBM Corporation, 2004. All rights reserved.
	* Copyright (C) Red Hat Inc., 2014. All rights reserved.
	* Authors:
	* Vivek Goyal <vgoyal@redhat.com>
	*
	*/

	#define pr_fmt(fmt) "kexec: " fmt

	#include <linux/types.h>
	#include <linux/kernel.h>
	#include <linux/smp.h>
	#include <linux/reboot.h>
	#include <linux/kexec.h>
	#include <linux/delay.h>
	#include <linux/elf.h>
	#include <linux/elfcore.h>
	#include <linux/export.h>
	#include <linux/slab.h>
	#include <linux/vmalloc.h>

	#include <asm/processor.h>
	#include <asm/hardirq.h>
	#include <asm/nmi.h>
	#include <asm/hw_irq.h>
	#include <asm/apic.h>
	#include <asm/io_apic.h>
	#include <asm/hpet.h>
	#include <linux/kdebug.h>
	#include <asm/cpu.h>
	#include <asm/reboot.h>
	#include <asm/virtext.h>
	#include <asm/intel_pt.h>

	/* Alignment required for elf header segment */
	#define ELF_CORE_HEADER_ALIGN 4096

	/* This primarily represents number of split ranges due to exclusion */
	#define CRASH_MAX_RANGES 16

	struct crash_mem_range {
	u64 start, end;
	};

	struct crash_mem {
	unsigned int nr_ranges;
	struct crash_mem_range ranges[CRASH_MAX_RANGES];
	};

	/* Misc data about ram ranges needed to prepare elf headers */
	struct crash_elf_data {
	struct kimage *image;
	/*
	* Total number of ram ranges we have after various adjustments for
	* crash reserved region, etc.
	*/
	unsigned int max_nr_ranges;

	/* Pointer to elf header */
	void *ehdr;
	/* Pointer to next phdr */
	void *bufp;
	struct crash_mem mem;
	};

	/* Used while preparing memory map entries for second kernel */
	struct crash_memmap_data {
	struct boot_params *params;
	/* Type of memory */
	unsigned int type;
	};

	/*
	* This is used to VMCLEAR all VMCSs loaded on the
	* processor. And when loading kvm_intel module, the
	* callback function pointer will be assigned.
	*
	* protected by rcu.
	*/
	crash_vmclear_fn __rcu *crash_vmclear_loaded_vmcss = NULL;
	EXPORT_SYMBOL_GPL(crash_vmclear_loaded_vmcss);
	unsigned long crash_zero_bytes;

	static inline void cpu_crash_vmclear_loaded_vmcss(void)
	{
	crash_vmclear_fn *do_vmclear_operation = NULL;

	rcu_read_lock();
	do_vmclear_operation = rcu_dereference(crash_vmclear_loaded_vmcss);
	if (do_vmclear_operation)
	do_vmclear_operation();
	rcu_read_unlock();
	}

	#if defined(CONFIG_SMP) && defined(CONFIG_X86_LOCAL_APIC)

	static void kdump_nmi_callback(int cpu, struct pt_regs *regs)
	{
	#ifdef CONFIG_X86_32
	struct pt_regs fixed_regs;

	if (!user_mode(regs)) {
	crash_fixup_ss_esp(&fixed_regs, regs);
	regs = &fixed_regs;
	}
	#endif
	crash_save_cpu(regs, cpu);

	/*
	* VMCLEAR VMCSs loaded on all cpus if needed.
	*/
	cpu_crash_vmclear_loaded_vmcss();

	/* Disable VMX or SVM if needed.
	*
	* We need to disable virtualization on all CPUs.
	* Having VMX or SVM enabled on any CPU may break rebooting
	* after the kdump kernel has finished its task.
	*/
	cpu_emergency_vmxoff();
	cpu_emergency_svm_disable();

	/*
	* Disable Intel PT to stop its logging
	*/
	cpu_emergency_stop_pt();

	disable_local_APIC();
	}

	static void kdump_nmi_shootdown_cpus(void)
	{
	nmi_shootdown_cpus(kdump_nmi_callback);

	disable_local_APIC();
	}

	#else
	static void kdump_nmi_shootdown_cpus(void)
	{
	/* There are no cpus to shootdown */
	}
	#endif

	void native_machine_crash_shutdown(struct pt_regs *regs)
	{
	/* This function is only called after the system
	* has panicked or is otherwise in a critical state.
	* The minimum amount of code to allow a kexec'd kernel
	* to run successfully needs to happen here.
	*
	* In practice this means shooting down the other cpus in
	* an SMP system.
	*/
	/* The kernel is broken so disable interrupts */
	local_irq_disable();

	kdump_nmi_shootdown_cpus();

	/*
	* VMCLEAR VMCSs loaded on this cpu if needed.
	*/
	cpu_crash_vmclear_loaded_vmcss();

	/* Booting kdump kernel with VMX or SVM enabled won't work,
	* because (among other limitations) we can't disable paging
	* with the virt flags.
	*/
	cpu_emergency_vmxoff();
	cpu_emergency_svm_disable();

	/*
	* Disable Intel PT to stop its logging
	*/
	cpu_emergency_stop_pt();

	#ifdef CONFIG_X86_IO_APIC
	/* Prevent crash_kexec() from deadlocking on ioapic_lock. */
	ioapic_zap_locks();
	disable_IO_APIC();
	#endif
	lapic_shutdown();
	#ifdef CONFIG_HPET_TIMER
	hpet_disable();
	#endif
	crash_save_cpu(regs, safe_smp_processor_id());
	}

	#ifdef CONFIG_KEXEC_FILE
	static int get_nr_ram_ranges_callback(u64 start, u64 end, void *arg)
	{
	unsigned int *nr_ranges = arg;

	(*nr_ranges)++;
	return 0;
	}


	/* Gather all the required information to prepare elf headers for ram regions */
	static void fill_up_crash_elf_data(struct crash_elf_data *ced,
	struct kimage *image)
	{
	unsigned int nr_ranges = 0;

	ced->image = image;

	walk_system_ram_res(0, -1, &nr_ranges,
	get_nr_ram_ranges_callback);

	ced->max_nr_ranges = nr_ranges;

	/* Exclusion of crash region could split memory ranges */
	ced->max_nr_ranges++;

	/* If crashk_low_res is not 0, another range split possible */
	if (crashk_low_res.end)
	ced->max_nr_ranges++;
	}

	static int exclude_mem_range(struct crash_mem *mem,
	unsigned long long mstart, unsigned long long mend)
	{
	int i, j;
	unsigned long long start, end;
	struct crash_mem_range temp_range = {0, 0};

	for (i = 0; i < mem->nr_ranges; i++) {
	start = mem->ranges[i].start;
	end = mem->ranges[i].end;

	if (mstart > end \|\| mend < start)
	continue;

	/* Truncate any area outside of range */
	if (mstart < start)
	mstart = start;
	if (mend > end)
	mend = end;

	/* Found completely overlapping range */
	if (mstart == start && mend == end) {
	mem->ranges[i].start = 0;
	mem->ranges[i].end = 0;
	if (i < mem->nr_ranges - 1) {
	/* Shift rest of the ranges to left */
	for (j = i; j < mem->nr_ranges - 1; j++) {
	mem->ranges[j].start =
	mem->ranges[j+1].start;
	mem->ranges[j].end =
	mem->ranges[j+1].end;
	}
	}
	mem->nr_ranges--;
	return 0;
	}

	if (mstart > start && mend < end) {
	/* Split original range */
	mem->ranges[i].end = mstart - 1;
	temp_range.start = mend + 1;
	temp_range.end = end;
	} else if (mstart != start)
	mem->ranges[i].end = mstart - 1;
	else
	mem->ranges[i].start = mend + 1;
	break;
	}

	/* If a split happend, add the split to array */
	if (!temp_range.end)
	return 0;

	/* Split happened */
	if (i == CRASH_MAX_RANGES - 1) {
	pr_err("Too many crash ranges after split\n");
	return -ENOMEM;
	}

	/* Location where new range should go */
	j = i + 1;
	if (j < mem->nr_ranges) {
	/* Move over all ranges one slot towards the end */
	for (i = mem->nr_ranges - 1; i >= j; i--)
	mem->ranges[i + 1] = mem->ranges[i];
	}

	mem->ranges[j].start = temp_range.start;
	mem->ranges[j].end = temp_range.end;
	mem->nr_ranges++;
	return 0;
	}

	/*
	* Look for any unwanted ranges between mstart, mend and remove them. This
	* might lead to split and split ranges are put in ced->mem.ranges[] array
	*/
	static int elf_header_exclude_ranges(struct crash_elf_data *ced,
	unsigned long long mstart, unsigned long long mend)
	{
	struct crash_mem *cmem = &ced->mem;
	int ret = 0;

	memset(cmem->ranges, 0, sizeof(cmem->ranges));

	cmem->ranges[0].start = mstart;
	cmem->ranges[0].end = mend;
	cmem->nr_ranges = 1;

	/* Exclude crashkernel region */
	ret = exclude_mem_range(cmem, crashk_res.start, crashk_res.end);
	if (ret)
	return ret;

	if (crashk_low_res.end) {
	ret = exclude_mem_range(cmem, crashk_low_res.start, crashk_low_res.end);
	if (ret)
	return ret;
	}

	return ret;
	}

	static int prepare_elf64_ram_headers_callback(u64 start, u64 end, void *arg)
	{
	struct crash_elf_data *ced = arg;
	Elf64_Ehdr *ehdr;
	Elf64_Phdr *phdr;
	unsigned long mstart, mend;
	struct kimage *image = ced->image;
	struct crash_mem *cmem;
	int ret, i;

	ehdr = ced->ehdr;

	/* Exclude unwanted mem ranges */
	ret = elf_header_exclude_ranges(ced, start, end);
	if (ret)
	return ret;

	/* Go through all the ranges in ced->mem.ranges[] and prepare phdr */
	cmem = &ced->mem;

	for (i = 0; i < cmem->nr_ranges; i++) {
	mstart = cmem->ranges[i].start;
	mend = cmem->ranges[i].end;

	phdr = ced->bufp;
	ced->bufp += sizeof(Elf64_Phdr);

	phdr->p_type = PT_LOAD;
	phdr->p_flags = PF_R\|PF_W\|PF_X;
	phdr->p_offset = mstart;

	/*
	* If a range matches backup region, adjust offset to backup
	* segment.
	*/
	if (mstart == image->arch.backup_src_start &&
	(mend - mstart + 1) == image->arch.backup_src_sz)
	phdr->p_offset = image->arch.backup_load_addr;

	phdr->p_paddr = mstart;
	phdr->p_vaddr = (unsigned long long) __va(mstart);
	phdr->p_filesz = phdr->p_memsz = mend - mstart + 1;
	phdr->p_align = 0;
	ehdr->e_phnum++;
	pr_debug("Crash PT_LOAD elf header. phdr=%p vaddr=0x%llx, paddr=0x%llx, sz=0x%llx e_phnum=%d p_offset=0x%llx\n",
	phdr, phdr->p_vaddr, phdr->p_paddr, phdr->p_filesz,
	ehdr->e_phnum, phdr->p_offset);
	}

	return ret;
	}

	static int prepare_elf64_headers(struct crash_elf_data *ced,
	void *addr, unsigned long sz)
	{
	Elf64_Ehdr *ehdr;
	Elf64_Phdr *phdr;
	unsigned long nr_cpus = num_possible_cpus(), nr_phdr, elf_sz;
	unsigned char buf, bufp;
	unsigned int cpu;
	unsigned long long notes_addr;
	int ret;

	/* extra phdr for vmcoreinfo elf note */
	nr_phdr = nr_cpus + 1;
	nr_phdr += ced->max_nr_ranges;

	/*
	* kexec-tools creates an extra PT_LOAD phdr for kernel text mapping
	* area on x86_64 (ffffffff80000000 - ffffffffa0000000).
	* I think this is required by tools like gdb. So same physical
	* memory will be mapped in two elf headers. One will contain kernel
	* text virtual addresses and other will have __va(physical) addresses.
	*/

	nr_phdr++;
	elf_sz = sizeof(Elf64_Ehdr) + nr_phdr * sizeof(Elf64_Phdr);
	elf_sz = ALIGN(elf_sz, ELF_CORE_HEADER_ALIGN);

	buf = vzalloc(elf_sz);
	if (!buf)
	return -ENOMEM;

	bufp = buf;
	ehdr = (Elf64_Ehdr *)bufp;
	bufp += sizeof(Elf64_Ehdr);
	memcpy(ehdr->e_ident, ELFMAG, SELFMAG);
	ehdr->e_ident[EI_CLASS] = ELFCLASS64;
	ehdr->e_ident[EI_DATA] = ELFDATA2LSB;
	ehdr->e_ident[EI_VERSION] = EV_CURRENT;
	ehdr->e_ident[EI_OSABI] = ELF_OSABI;
	memset(ehdr->e_ident + EI_PAD, 0, EI_NIDENT - EI_PAD);
	ehdr->e_type = ET_CORE;
	ehdr->e_machine = ELF_ARCH;
	ehdr->e_version = EV_CURRENT;
	ehdr->e_phoff = sizeof(Elf64_Ehdr);
	ehdr->e_ehsize = sizeof(Elf64_Ehdr);
	ehdr->e_phentsize = sizeof(Elf64_Phdr);

	/* Prepare one phdr of type PT_NOTE for each present cpu */
	for_each_present_cpu(cpu) {
	phdr = (Elf64_Phdr *)bufp;
	bufp += sizeof(Elf64_Phdr);
	phdr->p_type = PT_NOTE;
	notes_addr = per_cpu_ptr_to_phys(per_cpu_ptr(crash_notes, cpu));
	phdr->p_offset = phdr->p_paddr = notes_addr;
	phdr->p_filesz = phdr->p_memsz = sizeof(note_buf_t);
	(ehdr->e_phnum)++;
	}

	/* Prepare one PT_NOTE header for vmcoreinfo */
	phdr = (Elf64_Phdr *)bufp;
	bufp += sizeof(Elf64_Phdr);
	phdr->p_type = PT_NOTE;
	phdr->p_offset = phdr->p_paddr = paddr_vmcoreinfo_note();
	phdr->p_filesz = phdr->p_memsz = sizeof(vmcoreinfo_note);
	(ehdr->e_phnum)++;

	#ifdef CONFIG_X86_64
	/* Prepare PT_LOAD type program header for kernel text region */
	phdr = (Elf64_Phdr *)bufp;
	bufp += sizeof(Elf64_Phdr);
	phdr->p_type = PT_LOAD;
	phdr->p_flags = PF_R\|PF_W\|PF_X;
	phdr->p_vaddr = (Elf64_Addr)_text;
	phdr->p_filesz = phdr->p_memsz = _end - _text;
	phdr->p_offset = phdr->p_paddr = __pa_symbol(_text);
	(ehdr->e_phnum)++;
	#endif

	/* Prepare PT_LOAD headers for system ram chunks. */
	ced->ehdr = ehdr;
	ced->bufp = bufp;
	ret = walk_system_ram_res(0, -1, ced,
	prepare_elf64_ram_headers_callback);
	if (ret < 0)
	return ret;

	*addr = buf;
	*sz = elf_sz;
	return 0;
	}

	/* Prepare elf headers. Return addr and size */
	static int prepare_elf_headers(struct kimage image, void *addr,
	unsigned long *sz)
	{
	struct crash_elf_data *ced;
	int ret;

	ced = kzalloc(sizeof(*ced), GFP_KERNEL);
	if (!ced)
	return -ENOMEM;

	fill_up_crash_elf_data(ced, image);

	/* By default prepare 64bit headers */
	ret = prepare_elf64_headers(ced, addr, sz);
	kfree(ced);
	return ret;
	}

	static int add_e820_entry(struct boot_params params, struct e820entry entry)
	{
	unsigned int nr_e820_entries;

	nr_e820_entries = params->e820_entries;
	if (nr_e820_entries >= E820MAX)
	return 1;

	memcpy(&params->e820_map[nr_e820_entries], entry,
	sizeof(struct e820entry));
	params->e820_entries++;
	return 0;
	}

	static int memmap_entry_callback(u64 start, u64 end, void *arg)
	{
	struct crash_memmap_data *cmd = arg;
	struct boot_params *params = cmd->params;
	struct e820entry ei;

	ei.addr = start;
	ei.size = end - start + 1;
	ei.type = cmd->type;
	add_e820_entry(params, &ei);

	return 0;
	}

	static int memmap_exclude_ranges(struct kimage image, struct crash_mem cmem,
	unsigned long long mstart,
	unsigned long long mend)
	{
	unsigned long start, end;
	int ret = 0;

	cmem->ranges[0].start = mstart;
	cmem->ranges[0].end = mend;
	cmem->nr_ranges = 1;

	/* Exclude Backup region */
	start = image->arch.backup_load_addr;
	end = start + image->arch.backup_src_sz - 1;
	ret = exclude_mem_range(cmem, start, end);
	if (ret)
	return ret;

	/* Exclude elf header region */
	start = image->arch.elf_load_addr;
	end = start + image->arch.elf_headers_sz - 1;
	return exclude_mem_range(cmem, start, end);
	}

	/* Prepare memory map for crash dump kernel */
	int crash_setup_memmap_entries(struct kimage image, struct boot_params params)
	{
	int i, ret = 0;
	unsigned long flags;
	struct e820entry ei;
	struct crash_memmap_data cmd;
	struct crash_mem *cmem;

	cmem = vzalloc(sizeof(struct crash_mem));
	if (!cmem)
	return -ENOMEM;

	memset(&cmd, 0, sizeof(struct crash_memmap_data));
	cmd.params = params;

	/* Add first 640K segment */
	ei.addr = image->arch.backup_src_start;
	ei.size = image->arch.backup_src_sz;
	ei.type = E820_RAM;
	add_e820_entry(params, &ei);

	/* Add ACPI tables */
	cmd.type = E820_ACPI;
	flags = IORESOURCE_MEM \| IORESOURCE_BUSY;
	walk_iomem_res_desc(IORES_DESC_ACPI_TABLES, flags, 0, -1, &cmd,
	memmap_entry_callback);

	/* Add ACPI Non-volatile Storage */
	cmd.type = E820_NVS;
	walk_iomem_res_desc(IORES_DESC_ACPI_NV_STORAGE, flags, 0, -1, &cmd,
	memmap_entry_callback);

	/* Add crashk_low_res region */
	if (crashk_low_res.end) {
	ei.addr = crashk_low_res.start;
	ei.size = crashk_low_res.end - crashk_low_res.start + 1;
	ei.type = E820_RAM;
	add_e820_entry(params, &ei);
	}

	/* Exclude some ranges from crashk_res and add rest to memmap */
	ret = memmap_exclude_ranges(image, cmem, crashk_res.start,
	crashk_res.end);
	if (ret)
	goto out;

	for (i = 0; i < cmem->nr_ranges; i++) {
	ei.size = cmem->ranges[i].end - cmem->ranges[i].start + 1;

	/* If entry is less than a page, skip it */
	if (ei.size < PAGE_SIZE)
	continue;
	ei.addr = cmem->ranges[i].start;
	ei.type = E820_RAM;
	add_e820_entry(params, &ei);
	}

	out:
	vfree(cmem);
	return ret;
	}

	static int determine_backup_region(u64 start, u64 end, void *arg)
	{
	struct kimage *image = arg;

	image->arch.backup_src_start = start;
	image->arch.backup_src_sz = end - start + 1;

	/* Expecting only one range for backup region */
	return 1;
	}

	int crash_load_segments(struct kimage *image)
	{
	unsigned long src_start, src_sz, elf_sz;
	void *elf_addr;
	int ret;

	/*
	* Determine and load a segment for backup area. First 640K RAM
	* region is backup source
	*/

	ret = walk_system_ram_res(KEXEC_BACKUP_SRC_START, KEXEC_BACKUP_SRC_END,
	image, determine_backup_region);

	/* Zero or postive return values are ok */
	if (ret < 0)
	return ret;

	src_start = image->arch.backup_src_start;
	src_sz = image->arch.backup_src_sz;

	/* Add backup segment. */
	if (src_sz) {
	/*
	* Ideally there is no source for backup segment. This is
	* copied in purgatory after crash. Just add a zero filled
	* segment for now to make sure checksum logic works fine.
	*/
	ret = kexec_add_buffer(image, (char *)&crash_zero_bytes,
	sizeof(crash_zero_bytes), src_sz,
	PAGE_SIZE, 0, -1, 0,
	&image->arch.backup_load_addr);
	if (ret)
	return ret;
	pr_debug("Loaded backup region at 0x%lx backup_start=0x%lx memsz=0x%lx\n",
	image->arch.backup_load_addr, src_start, src_sz);
	}

	/* Prepare elf headers and add a segment */
	ret = prepare_elf_headers(image, &elf_addr, &elf_sz);
	if (ret)
	return ret;

	image->arch.elf_headers = elf_addr;
	image->arch.elf_headers_sz = elf_sz;

	ret = kexec_add_buffer(image, (char *)elf_addr, elf_sz, elf_sz,
	ELF_CORE_HEADER_ALIGN, 0, -1, 0,
	&image->arch.elf_load_addr);
	if (ret) {
	vfree((void *)image->arch.elf_headers);
	return ret;
	}
	pr_debug("Loaded ELF headers at 0x%lx bufsz=0x%lx memsz=0x%lx\n",
	image->arch.elf_load_addr, elf_sz, elf_sz);

	return ret;
	}
	#endif /* CONFIG_KEXEC_FILE */