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

 // SPDX-License-Identifier: GPL-2.0-only
 /*
  * 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/e820/types.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>
 #include <asm/crash.h>

 /* 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);

 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)
 {
 	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();
 }

 void kdump_nmi_shootdown_cpus(void)
 {
 	nmi_shootdown_cpus(kdump_nmi_callback);

 	disable_local_APIC();
 }

 /* Override the weak function in kernel/panic.c */
 void crash_smp_send_stop(void)
 {
 	static int cpus_stopped;

 	if (cpus_stopped)
 		return;

 	if (smp_ops.crash_stop_other_cpus)
 		smp_ops.crash_stop_other_cpus();
 	else
 		smp_send_stop();

 	cpus_stopped = 1;
 }

 #else
 void crash_smp_send_stop(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();

 	crash_smp_send_stop();

 	/*
 	 * 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();
 	clear_IO_APIC();
 #endif
 	lapic_shutdown();
 	restore_boot_irq_mode();
 #ifdef CONFIG_HPET_TIMER
 	hpet_disable();
 #endif
 	crash_save_cpu(regs, safe_smp_processor_id());
 }

 #ifdef CONFIG_KEXEC_FILE

 static unsigned long crash_zero_bytes;

 static int get_nr_ram_ranges_callback(struct resource *res, void *arg)
 {
 	unsigned int *nr_ranges = arg;

 	(*nr_ranges)++;
 	return 0;
 }

 /* Gather all the required information to prepare elf headers for ram regions */
 static struct crash_mem *fill_up_crash_elf_data(void)
 {
 	unsigned int nr_ranges = 0;
 	struct crash_mem *cmem;

 	walk_system_ram_res(0, -1, &nr_ranges,
 				get_nr_ram_ranges_callback);
 	if (!nr_ranges)
 		return NULL;

 	/*
 	 * Exclusion of crash region and/or crashk_low_res may cause
 	 * another range split. So add extra two slots here.
 	 */
 	nr_ranges += 2;
 	cmem = vzalloc(struct_size(cmem, ranges, nr_ranges));
 	if (!cmem)
 		return NULL;

 	cmem->max_nr_ranges = nr_ranges;
 	cmem->nr_ranges = 0;

 	return cmem;
 }

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

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

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

 	return ret;
 }

 static int prepare_elf64_ram_headers_callback(struct resource *res, void *arg)
 {
 	struct crash_mem *cmem = arg;

 	cmem->ranges[cmem->nr_ranges].start = res->start;
 	cmem->ranges[cmem->nr_ranges].end = res->end;
 	cmem->nr_ranges++;

 	return 0;
 }

 /* Prepare elf headers. Return addr and size */
 static int prepare_elf_headers(struct kimage *image, void **addr,
 					unsigned long *sz)
 {
 	struct crash_mem *cmem;
 	Elf64_Ehdr *ehdr;
 	Elf64_Phdr *phdr;
 	int ret, i;

 	cmem = fill_up_crash_elf_data();
 	if (!cmem)
 		return -ENOMEM;

 	ret = walk_system_ram_res(0, -1, cmem,
 				prepare_elf64_ram_headers_callback);
 	if (ret)
 		goto out;

 	/* Exclude unwanted mem ranges */
 	ret = elf_header_exclude_ranges(cmem);
 	if (ret)
 		goto out;

 	/* By default prepare 64bit headers */
 	ret =  crash_prepare_elf64_headers(cmem,
 				IS_ENABLED(CONFIG_X86_64), addr, sz);
 	if (ret)
 		goto out;

 	/*
 	 * If a range matches backup region, adjust offset to backup
 	 * segment.
 	 */
 	ehdr = (Elf64_Ehdr *)*addr;
 	phdr = (Elf64_Phdr *)(ehdr + 1);
 	for (i = 0; i < ehdr->e_phnum; phdr++, i++)
 		if (phdr->p_type == PT_LOAD &&
 				phdr->p_paddr == image->arch.backup_src_start &&
 				phdr->p_memsz == image->arch.backup_src_sz) {
 			phdr->p_offset = image->arch.backup_load_addr;
 			break;
 		}
 out:
 	vfree(cmem);
 	return ret;
 }

 static int add_e820_entry(struct boot_params *params, struct e820_entry *entry)
 {
 	unsigned int nr_e820_entries;

 	nr_e820_entries = params->e820_entries;
 	if (nr_e820_entries >= E820_MAX_ENTRIES_ZEROPAGE)
 		return 1;

 	memcpy(&params->e820_table[nr_e820_entries], entry,
 			sizeof(struct e820_entry));
 	params->e820_entries++;
 	return 0;
 }

 static int memmap_entry_callback(struct resource *res, void *arg)
 {
 	struct crash_memmap_data *cmd = arg;
 	struct boot_params *params = cmd->params;
 	struct e820_entry ei;

 	ei.addr = res->start;
 	ei.size = resource_size(res);
 	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 = crash_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 crash_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 e820_entry 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_TYPE_RAM;
 	add_e820_entry(params, &ei);

 	/* Add ACPI tables */
 	cmd.type = E820_TYPE_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_TYPE_NVS;
 	walk_iomem_res_desc(IORES_DESC_ACPI_NV_STORAGE, flags, 0, -1, &cmd,
 			memmap_entry_callback);

 	/* Add e820 reserved ranges */
 	cmd.type = E820_TYPE_RESERVED;
 	flags = IORESOURCE_MEM;
 	walk_iomem_res_desc(IORES_DESC_RESERVED, 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_TYPE_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_TYPE_RAM;
 		add_e820_entry(params, &ei);
 	}

 out:
 	vfree(cmem);
 	return ret;
 }

 static int determine_backup_region(struct resource *res, void *arg)
 {
 	struct kimage *image = arg;

 	image->arch.backup_src_start = res->start;
 	image->arch.backup_src_sz = resource_size(res);

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

 int crash_load_segments(struct kimage *image)
 {
 	int ret;
 	struct kexec_buf kbuf = { .image = image, .buf_min = 0,
 				  .buf_max = ULONG_MAX, .top_down = false };

 	/*
 	 * 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;

 	/* Add backup segment. */
 	if (image->arch.backup_src_sz) {
 		kbuf.buffer = &crash_zero_bytes;
 		kbuf.bufsz = sizeof(crash_zero_bytes);
 		kbuf.memsz = image->arch.backup_src_sz;
 		kbuf.buf_align = PAGE_SIZE;
 		/*
 		 * 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(&kbuf);
 		if (ret)
 			return ret;
 		image->arch.backup_load_addr = kbuf.mem;
 		pr_debug("Loaded backup region at 0x%lx backup_start=0x%lx memsz=0x%lx\n",
 			 image->arch.backup_load_addr,
 			 image->arch.backup_src_start, kbuf.memsz);
 	}

 	/* Prepare elf headers and add a segment */
 	ret = prepare_elf_headers(image, &kbuf.buffer, &kbuf.bufsz);
 	if (ret)
 		return ret;

 	image->arch.elf_headers = kbuf.buffer;
 	image->arch.elf_headers_sz = kbuf.bufsz;

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

 	return ret;
 }
 #endif /* CONFIG_KEXEC_FILE */
	// SPDX-License-Identifier: GPL-2.0-only
	/*
	* 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/e820/types.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>
	#include <asm/crash.h>

	/* 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);

	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)
	{
	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();
	}

	void kdump_nmi_shootdown_cpus(void)
	{
	nmi_shootdown_cpus(kdump_nmi_callback);

	disable_local_APIC();
	}

	/* Override the weak function in kernel/panic.c */
	void crash_smp_send_stop(void)
	{
	static int cpus_stopped;

	if (cpus_stopped)
	return;

	if (smp_ops.crash_stop_other_cpus)
	smp_ops.crash_stop_other_cpus();
	else
	smp_send_stop();

	cpus_stopped = 1;
	}

	#else
	void crash_smp_send_stop(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();

	crash_smp_send_stop();

	/*
	* 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();
	clear_IO_APIC();
	#endif
	lapic_shutdown();
	restore_boot_irq_mode();
	#ifdef CONFIG_HPET_TIMER
	hpet_disable();
	#endif
	crash_save_cpu(regs, safe_smp_processor_id());
	}

	#ifdef CONFIG_KEXEC_FILE

	static unsigned long crash_zero_bytes;

	static int get_nr_ram_ranges_callback(struct resource res, void arg)
	{
	unsigned int *nr_ranges = arg;

	(*nr_ranges)++;
	return 0;
	}

	/* Gather all the required information to prepare elf headers for ram regions */
	static struct crash_mem *fill_up_crash_elf_data(void)
	{
	unsigned int nr_ranges = 0;
	struct crash_mem *cmem;

	walk_system_ram_res(0, -1, &nr_ranges,
	get_nr_ram_ranges_callback);
	if (!nr_ranges)
	return NULL;

	/*
	* Exclusion of crash region and/or crashk_low_res may cause
	* another range split. So add extra two slots here.
	*/
	nr_ranges += 2;
	cmem = vzalloc(struct_size(cmem, ranges, nr_ranges));
	if (!cmem)
	return NULL;

	cmem->max_nr_ranges = nr_ranges;
	cmem->nr_ranges = 0;

	return cmem;
	}

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

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

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

	return ret;
	}

	static int prepare_elf64_ram_headers_callback(struct resource res, void arg)
	{
	struct crash_mem *cmem = arg;

	cmem->ranges[cmem->nr_ranges].start = res->start;
	cmem->ranges[cmem->nr_ranges].end = res->end;
	cmem->nr_ranges++;

	return 0;
	}

	/* Prepare elf headers. Return addr and size */
	static int prepare_elf_headers(struct kimage image, void *addr,
	unsigned long *sz)
	{
	struct crash_mem *cmem;
	Elf64_Ehdr *ehdr;
	Elf64_Phdr *phdr;
	int ret, i;

	cmem = fill_up_crash_elf_data();
	if (!cmem)
	return -ENOMEM;

	ret = walk_system_ram_res(0, -1, cmem,
	prepare_elf64_ram_headers_callback);
	if (ret)
	goto out;

	/* Exclude unwanted mem ranges */
	ret = elf_header_exclude_ranges(cmem);
	if (ret)
	goto out;

	/* By default prepare 64bit headers */
	ret = crash_prepare_elf64_headers(cmem,
	IS_ENABLED(CONFIG_X86_64), addr, sz);
	if (ret)
	goto out;

	/*
	* If a range matches backup region, adjust offset to backup
	* segment.
	*/
	ehdr = (Elf64_Ehdr )addr;
	phdr = (Elf64_Phdr *)(ehdr + 1);
	for (i = 0; i < ehdr->e_phnum; phdr++, i++)
	if (phdr->p_type == PT_LOAD &&
	phdr->p_paddr == image->arch.backup_src_start &&
	phdr->p_memsz == image->arch.backup_src_sz) {
	phdr->p_offset = image->arch.backup_load_addr;
	break;
	}
	out:
	vfree(cmem);
	return ret;
	}

	static int add_e820_entry(struct boot_params params, struct e820_entry entry)
	{
	unsigned int nr_e820_entries;

	nr_e820_entries = params->e820_entries;
	if (nr_e820_entries >= E820_MAX_ENTRIES_ZEROPAGE)
	return 1;

	memcpy(&params->e820_table[nr_e820_entries], entry,
	sizeof(struct e820_entry));
	params->e820_entries++;
	return 0;
	}

	static int memmap_entry_callback(struct resource res, void arg)
	{
	struct crash_memmap_data *cmd = arg;
	struct boot_params *params = cmd->params;
	struct e820_entry ei;

	ei.addr = res->start;
	ei.size = resource_size(res);
	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 = crash_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 crash_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 e820_entry 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_TYPE_RAM;
	add_e820_entry(params, &ei);

	/* Add ACPI tables */
	cmd.type = E820_TYPE_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_TYPE_NVS;
	walk_iomem_res_desc(IORES_DESC_ACPI_NV_STORAGE, flags, 0, -1, &cmd,
	memmap_entry_callback);

	/* Add e820 reserved ranges */
	cmd.type = E820_TYPE_RESERVED;
	flags = IORESOURCE_MEM;
	walk_iomem_res_desc(IORES_DESC_RESERVED, 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_TYPE_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_TYPE_RAM;
	add_e820_entry(params, &ei);
	}

	out:
	vfree(cmem);
	return ret;
	}

	static int determine_backup_region(struct resource res, void arg)
	{
	struct kimage *image = arg;

	image->arch.backup_src_start = res->start;
	image->arch.backup_src_sz = resource_size(res);

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

	int crash_load_segments(struct kimage *image)
	{
	int ret;
	struct kexec_buf kbuf = { .image = image, .buf_min = 0,
	.buf_max = ULONG_MAX, .top_down = false };

	/*
	* 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;

	/* Add backup segment. */
	if (image->arch.backup_src_sz) {
	kbuf.buffer = &crash_zero_bytes;
	kbuf.bufsz = sizeof(crash_zero_bytes);
	kbuf.memsz = image->arch.backup_src_sz;
	kbuf.buf_align = PAGE_SIZE;
	/*
	* 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(&kbuf);
	if (ret)
	return ret;
	image->arch.backup_load_addr = kbuf.mem;
	pr_debug("Loaded backup region at 0x%lx backup_start=0x%lx memsz=0x%lx\n",
	image->arch.backup_load_addr,
	image->arch.backup_src_start, kbuf.memsz);
	}

	/* Prepare elf headers and add a segment */
	ret = prepare_elf_headers(image, &kbuf.buffer, &kbuf.bufsz);
	if (ret)
	return ret;

	image->arch.elf_headers = kbuf.buffer;
	image->arch.elf_headers_sz = kbuf.bufsz;

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

	return ret;
	}
	#endif /* CONFIG_KEXEC_FILE */