Contributors: 4
Author Tokens Token Proportion Commits Commit Proportion
Hari Bathini 2802 99.89% 15 83.33%
Julia Lawall 1 0.04% 1 5.56%
Nick Child 1 0.04% 1 5.56%
Christophe Leroy 1 0.04% 1 5.56%
Total 2805 18 


// SPDX-License-Identifier: GPL-2.0-or-later
/*
 * Firmware-Assisted Dump support on POWER platform (OPAL).
 *
 * Copyright 2019, Hari Bathini, IBM Corporation.
 */

#define pr_fmt(fmt) "opal fadump: " fmt

#include <linux/string.h>
#include <linux/seq_file.h>
#include <linux/of.h>
#include <linux/of_fdt.h>
#include <linux/libfdt.h>
#include <linux/mm.h>
#include <linux/crash_dump.h>

#include <asm/page.h>
#include <asm/opal.h>
#include <asm/fadump-internal.h>

#include "opal-fadump.h"


#ifdef CONFIG_PRESERVE_FA_DUMP
/*
 * When dump is active but PRESERVE_FA_DUMP is enabled on the kernel,
 * ensure crash data is preserved in hope that the subsequent memory
 * preserving kernel boot is going to process this crash data.
 */
void __init opal_fadump_dt_scan(struct fw_dump *fadump_conf, u64 node)
{
	const struct opal_fadump_mem_struct *opal_fdm_active;
	const __be32 *prop;
	unsigned long dn;
	u64 addr = 0;
	s64 ret;

	dn = of_get_flat_dt_subnode_by_name(node, "dump");
	if (dn == -FDT_ERR_NOTFOUND)
		return;

	/*
	 * Check if dump has been initiated on last reboot.
	 */
	prop = of_get_flat_dt_prop(dn, "mpipl-boot", NULL);
	if (!prop)
		return;

	ret = opal_mpipl_query_tag(OPAL_MPIPL_TAG_KERNEL, &addr);
	if ((ret != OPAL_SUCCESS) || !addr) {
		pr_debug("Could not get Kernel metadata (%lld)\n", ret);
		return;
	}

	/*
	 * Preserve memory only if kernel memory regions are registered
	 * with f/w for MPIPL.
	 */
	addr = be64_to_cpu(addr);
	pr_debug("Kernel metadata addr: %llx\n", addr);
	opal_fdm_active = (void *)addr;
	if (be16_to_cpu(opal_fdm_active->registered_regions) == 0)
		return;

	ret = opal_mpipl_query_tag(OPAL_MPIPL_TAG_BOOT_MEM, &addr);
	if ((ret != OPAL_SUCCESS) || !addr) {
		pr_err("Failed to get boot memory tag (%lld)\n", ret);
		return;
	}

	/*
	 * Memory below this address can be used for booting a
	 * capture kernel or petitboot kernel. Preserve everything
	 * above this address for processing crashdump.
	 */
	fadump_conf->boot_mem_top = be64_to_cpu(addr);
	pr_debug("Preserve everything above %llx\n", fadump_conf->boot_mem_top);

	pr_info("Firmware-assisted dump is active.\n");
	fadump_conf->dump_active = 1;
}

#else /* CONFIG_PRESERVE_FA_DUMP */
static const struct opal_fadump_mem_struct *opal_fdm_active;
static const struct opal_mpipl_fadump *opal_cpu_metadata;
static struct opal_fadump_mem_struct *opal_fdm;

#ifdef CONFIG_OPAL_CORE
extern bool kernel_initiated;
#endif

static int opal_fadump_unregister(struct fw_dump *fadump_conf);

static void opal_fadump_update_config(struct fw_dump *fadump_conf,
				      const struct opal_fadump_mem_struct *fdm)
{
	pr_debug("Boot memory regions count: %d\n", be16_to_cpu(fdm->region_cnt));

	/*
	 * The destination address of the first boot memory region is the
	 * destination address of boot memory regions.
	 */
	fadump_conf->boot_mem_dest_addr = be64_to_cpu(fdm->rgn[0].dest);
	pr_debug("Destination address of boot memory regions: %#016llx\n",
		 fadump_conf->boot_mem_dest_addr);

	fadump_conf->fadumphdr_addr = be64_to_cpu(fdm->fadumphdr_addr);
}

/*
 * This function is called in the capture kernel to get configuration details
 * from metadata setup by the first kernel.
 */
static void __init opal_fadump_get_config(struct fw_dump *fadump_conf,
				   const struct opal_fadump_mem_struct *fdm)
{
	unsigned long base, size, last_end, hole_size;
	int i;

	if (!fadump_conf->dump_active)
		return;

	last_end = 0;
	hole_size = 0;
	fadump_conf->boot_memory_size = 0;

	pr_debug("Boot memory regions:\n");
	for (i = 0; i < be16_to_cpu(fdm->region_cnt); i++) {
		base = be64_to_cpu(fdm->rgn[i].src);
		size = be64_to_cpu(fdm->rgn[i].size);
		pr_debug("\t[%03d] base: 0x%lx, size: 0x%lx\n", i, base, size);

		fadump_conf->boot_mem_addr[i] = base;
		fadump_conf->boot_mem_sz[i] = size;
		fadump_conf->boot_memory_size += size;
		hole_size += (base - last_end);

		last_end = base + size;
	}

	/*
	 * Start address of reserve dump area (permanent reservation) for
	 * re-registering FADump after dump capture.
	 */
	fadump_conf->reserve_dump_area_start = be64_to_cpu(fdm->rgn[0].dest);

	/*
	 * Rarely, but it can so happen that system crashes before all
	 * boot memory regions are registered for MPIPL. In such
	 * cases, warn that the vmcore may not be accurate and proceed
	 * anyway as that is the best bet considering free pages, cache
	 * pages, user pages, etc are usually filtered out.
	 *
	 * Hope the memory that could not be preserved only has pages
	 * that are usually filtered out while saving the vmcore.
	 */
	if (be16_to_cpu(fdm->region_cnt) > be16_to_cpu(fdm->registered_regions)) {
		pr_warn("Not all memory regions were saved!!!\n");
		pr_warn("  Unsaved memory regions:\n");
		i = be16_to_cpu(fdm->registered_regions);
		while (i < be16_to_cpu(fdm->region_cnt)) {
			pr_warn("\t[%03d] base: 0x%llx, size: 0x%llx\n",
				i, be64_to_cpu(fdm->rgn[i].src),
				be64_to_cpu(fdm->rgn[i].size));
			i++;
		}

		pr_warn("If the unsaved regions only contain pages that are filtered out (eg. free/user pages), the vmcore should still be usable.\n");
		pr_warn("WARNING: If the unsaved regions contain kernel pages, the vmcore will be corrupted.\n");
	}

	fadump_conf->boot_mem_top = (fadump_conf->boot_memory_size + hole_size);
	fadump_conf->boot_mem_regs_cnt = be16_to_cpu(fdm->region_cnt);
	opal_fadump_update_config(fadump_conf, fdm);
}

/* Initialize kernel metadata */
static void opal_fadump_init_metadata(struct opal_fadump_mem_struct *fdm)
{
	fdm->version = OPAL_FADUMP_VERSION;
	fdm->region_cnt = cpu_to_be16(0);
	fdm->registered_regions = cpu_to_be16(0);
	fdm->fadumphdr_addr = cpu_to_be64(0);
}

static u64 opal_fadump_init_mem_struct(struct fw_dump *fadump_conf)
{
	u64 addr = fadump_conf->reserve_dump_area_start;
	u16 reg_cnt;
	int i;

	opal_fdm = __va(fadump_conf->kernel_metadata);
	opal_fadump_init_metadata(opal_fdm);

	/* Boot memory regions */
	reg_cnt = be16_to_cpu(opal_fdm->region_cnt);
	for (i = 0; i < fadump_conf->boot_mem_regs_cnt; i++) {
		opal_fdm->rgn[i].src	= cpu_to_be64(fadump_conf->boot_mem_addr[i]);
		opal_fdm->rgn[i].dest	= cpu_to_be64(addr);
		opal_fdm->rgn[i].size	= cpu_to_be64(fadump_conf->boot_mem_sz[i]);

		reg_cnt++;
		addr += fadump_conf->boot_mem_sz[i];
	}
	opal_fdm->region_cnt = cpu_to_be16(reg_cnt);

	/*
	 * Kernel metadata is passed to f/w and retrieved in capture kernel.
	 * So, use it to save fadump header address instead of calculating it.
	 */
	opal_fdm->fadumphdr_addr = cpu_to_be64(be64_to_cpu(opal_fdm->rgn[0].dest) +
					       fadump_conf->boot_memory_size);

	opal_fadump_update_config(fadump_conf, opal_fdm);

	return addr;
}

static u64 opal_fadump_get_metadata_size(void)
{
	return PAGE_ALIGN(sizeof(struct opal_fadump_mem_struct));
}

static int opal_fadump_setup_metadata(struct fw_dump *fadump_conf)
{
	int err = 0;
	s64 ret;

	/*
	 * Use the last page(s) in FADump memory reservation for
	 * kernel metadata.
	 */
	fadump_conf->kernel_metadata = (fadump_conf->reserve_dump_area_start +
					fadump_conf->reserve_dump_area_size -
					opal_fadump_get_metadata_size());
	pr_info("Kernel metadata addr: %llx\n", fadump_conf->kernel_metadata);

	/* Initialize kernel metadata before registering the address with f/w */
	opal_fdm = __va(fadump_conf->kernel_metadata);
	opal_fadump_init_metadata(opal_fdm);

	/*
	 * Register metadata address with f/w. Can be retrieved in
	 * the capture kernel.
	 */
	ret = opal_mpipl_register_tag(OPAL_MPIPL_TAG_KERNEL,
				      fadump_conf->kernel_metadata);
	if (ret != OPAL_SUCCESS) {
		pr_err("Failed to set kernel metadata tag!\n");
		err = -EPERM;
	}

	/*
	 * Register boot memory top address with f/w. Should be retrieved
	 * by a kernel that intends to preserve crash'ed kernel's memory.
	 */
	ret = opal_mpipl_register_tag(OPAL_MPIPL_TAG_BOOT_MEM,
				      fadump_conf->boot_mem_top);
	if (ret != OPAL_SUCCESS) {
		pr_err("Failed to set boot memory tag!\n");
		err = -EPERM;
	}

	return err;
}

static u64 opal_fadump_get_bootmem_min(void)
{
	return OPAL_FADUMP_MIN_BOOT_MEM;
}

static int opal_fadump_register(struct fw_dump *fadump_conf)
{
	s64 rc = OPAL_PARAMETER;
	u16 registered_regs;
	int i, err = -EIO;

	registered_regs = be16_to_cpu(opal_fdm->registered_regions);
	for (i = 0; i < be16_to_cpu(opal_fdm->region_cnt); i++) {
		rc = opal_mpipl_update(OPAL_MPIPL_ADD_RANGE,
				       be64_to_cpu(opal_fdm->rgn[i].src),
				       be64_to_cpu(opal_fdm->rgn[i].dest),
				       be64_to_cpu(opal_fdm->rgn[i].size));
		if (rc != OPAL_SUCCESS)
			break;

		registered_regs++;
	}
	opal_fdm->registered_regions = cpu_to_be16(registered_regs);

	switch (rc) {
	case OPAL_SUCCESS:
		pr_info("Registration is successful!\n");
		fadump_conf->dump_registered = 1;
		err = 0;
		break;
	case OPAL_RESOURCE:
		/* If MAX regions limit in f/w is hit, warn and proceed. */
		pr_warn("%d regions could not be registered for MPIPL as MAX limit is reached!\n",
			(be16_to_cpu(opal_fdm->region_cnt) -
			 be16_to_cpu(opal_fdm->registered_regions)));
		fadump_conf->dump_registered = 1;
		err = 0;
		break;
	case OPAL_PARAMETER:
		pr_err("Failed to register. Parameter Error(%lld).\n", rc);
		break;
	case OPAL_HARDWARE:
		pr_err("Support not available.\n");
		fadump_conf->fadump_supported = 0;
		fadump_conf->fadump_enabled = 0;
		break;
	default:
		pr_err("Failed to register. Unknown Error(%lld).\n", rc);
		break;
	}

	/*
	 * If some regions were registered before OPAL_MPIPL_ADD_RANGE
	 * OPAL call failed, unregister all regions.
	 */
	if ((err < 0) && (be16_to_cpu(opal_fdm->registered_regions) > 0))
		opal_fadump_unregister(fadump_conf);

	return err;
}

static int opal_fadump_unregister(struct fw_dump *fadump_conf)
{
	s64 rc;

	rc = opal_mpipl_update(OPAL_MPIPL_REMOVE_ALL, 0, 0, 0);
	if (rc) {
		pr_err("Failed to un-register - unexpected Error(%lld).\n", rc);
		return -EIO;
	}

	opal_fdm->registered_regions = cpu_to_be16(0);
	fadump_conf->dump_registered = 0;
	return 0;
}

static int opal_fadump_invalidate(struct fw_dump *fadump_conf)
{
	s64 rc;

	rc = opal_mpipl_update(OPAL_MPIPL_FREE_PRESERVED_MEMORY, 0, 0, 0);
	if (rc) {
		pr_err("Failed to invalidate - unexpected Error(%lld).\n", rc);
		return -EIO;
	}

	fadump_conf->dump_active = 0;
	opal_fdm_active = NULL;
	return 0;
}

static void opal_fadump_cleanup(struct fw_dump *fadump_conf)
{
	s64 ret;

	ret = opal_mpipl_register_tag(OPAL_MPIPL_TAG_KERNEL, 0);
	if (ret != OPAL_SUCCESS)
		pr_warn("Could not reset (%llu) kernel metadata tag!\n", ret);
}

/*
 * Verify if CPU state data is available. If available, do a bit of sanity
 * checking before processing this data.
 */
static bool __init is_opal_fadump_cpu_data_valid(struct fw_dump *fadump_conf)
{
	if (!opal_cpu_metadata)
		return false;

	fadump_conf->cpu_state_data_version =
		be32_to_cpu(opal_cpu_metadata->cpu_data_version);
	fadump_conf->cpu_state_entry_size =
		be32_to_cpu(opal_cpu_metadata->cpu_data_size);
	fadump_conf->cpu_state_dest_vaddr =
		(u64)__va(be64_to_cpu(opal_cpu_metadata->region[0].dest));
	fadump_conf->cpu_state_data_size =
		be64_to_cpu(opal_cpu_metadata->region[0].size);

	if (fadump_conf->cpu_state_data_version != HDAT_FADUMP_CPU_DATA_VER) {
		pr_warn("Supported CPU state data version: %u, found: %d!\n",
			HDAT_FADUMP_CPU_DATA_VER,
			fadump_conf->cpu_state_data_version);
		pr_warn("WARNING: F/W using newer CPU state data format!!\n");
	}

	if ((fadump_conf->cpu_state_dest_vaddr == 0) ||
	    (fadump_conf->cpu_state_entry_size == 0) ||
	    (fadump_conf->cpu_state_entry_size >
	     fadump_conf->cpu_state_data_size)) {
		pr_err("CPU state data is invalid. Ignoring!\n");
		return false;
	}

	return true;
}

/*
 * Convert CPU state data saved at the time of crash into ELF notes.
 *
 * While the crashing CPU's register data is saved by the kernel, CPU state
 * data for all CPUs is saved by f/w. In CPU state data provided by f/w,
 * each register entry is of 16 bytes, a numerical identifier along with
 * a GPR/SPR flag in the first 8 bytes and the register value in the next
 * 8 bytes. For more details refer to F/W documentation. If this data is
 * missing or in unsupported format, append crashing CPU's register data
 * saved by the kernel in the PT_NOTE, to have something to work with in
 * the vmcore file.
 */
static int __init
opal_fadump_build_cpu_notes(struct fw_dump *fadump_conf,
			    struct fadump_crash_info_header *fdh)
{
	u32 thread_pir, size_per_thread, regs_offset, regs_cnt, reg_esize;
	struct hdat_fadump_thread_hdr *thdr;
	bool is_cpu_data_valid = false;
	u32 num_cpus = 1, *note_buf;
	struct pt_regs regs;
	char *bufp;
	int rc, i;

	if (is_opal_fadump_cpu_data_valid(fadump_conf)) {
		size_per_thread = fadump_conf->cpu_state_entry_size;
		num_cpus = (fadump_conf->cpu_state_data_size / size_per_thread);
		bufp = __va(fadump_conf->cpu_state_dest_vaddr);
		is_cpu_data_valid = true;
	}

	rc = fadump_setup_cpu_notes_buf(num_cpus);
	if (rc != 0)
		return rc;

	note_buf = (u32 *)fadump_conf->cpu_notes_buf_vaddr;
	if (!is_cpu_data_valid)
		goto out;

	/*
	 * Offset for register entries, entry size and registers count is
	 * duplicated in every thread header in keeping with HDAT format.
	 * Use these values from the first thread header.
	 */
	thdr = (struct hdat_fadump_thread_hdr *)bufp;
	regs_offset = (offsetof(struct hdat_fadump_thread_hdr, offset) +
		       be32_to_cpu(thdr->offset));
	reg_esize = be32_to_cpu(thdr->esize);
	regs_cnt  = be32_to_cpu(thdr->ecnt);

	pr_debug("--------CPU State Data------------\n");
	pr_debug("NumCpus     : %u\n", num_cpus);
	pr_debug("\tOffset: %u, Entry size: %u, Cnt: %u\n",
		 regs_offset, reg_esize, regs_cnt);

	for (i = 0; i < num_cpus; i++, bufp += size_per_thread) {
		thdr = (struct hdat_fadump_thread_hdr *)bufp;

		thread_pir = be32_to_cpu(thdr->pir);
		pr_debug("[%04d] PIR: 0x%x, core state: 0x%02x\n",
			 i, thread_pir, thdr->core_state);

		/*
		 * If this is kernel initiated crash, crashing_cpu would be set
		 * appropriately and register data of the crashing CPU saved by
		 * crashing kernel. Add this saved register data of crashing CPU
		 * to elf notes and populate the pt_regs for the remaining CPUs
		 * from register state data provided by firmware.
		 */
		if (fdh->crashing_cpu == thread_pir) {
			note_buf = fadump_regs_to_elf_notes(note_buf,
							    &fdh->regs);
			pr_debug("Crashing CPU PIR: 0x%x - R1 : 0x%lx, NIP : 0x%lx\n",
				 fdh->crashing_cpu, fdh->regs.gpr[1],
				 fdh->regs.nip);
			continue;
		}

		/*
		 * Register state data of MAX cores is provided by firmware,
		 * but some of this cores may not be active. So, while
		 * processing register state data, check core state and
		 * skip threads that belong to inactive cores.
		 */
		if (thdr->core_state == HDAT_FADUMP_CORE_INACTIVE)
			continue;

		opal_fadump_read_regs((bufp + regs_offset), regs_cnt,
				      reg_esize, true, &regs);
		note_buf = fadump_regs_to_elf_notes(note_buf, &regs);
		pr_debug("CPU PIR: 0x%x - R1 : 0x%lx, NIP : 0x%lx\n",
			 thread_pir, regs.gpr[1], regs.nip);
	}

out:
	/*
	 * CPU state data is invalid/unsupported. Try appending crashing CPU's
	 * register data, if it is saved by the kernel.
	 */
	if (fadump_conf->cpu_notes_buf_vaddr == (u64)note_buf) {
		if (fdh->crashing_cpu == FADUMP_CPU_UNKNOWN) {
			fadump_free_cpu_notes_buf();
			return -ENODEV;
		}

		pr_warn("WARNING: appending only crashing CPU's register data\n");
		note_buf = fadump_regs_to_elf_notes(note_buf, &(fdh->regs));
	}

	final_note(note_buf);

	pr_debug("Updating elfcore header (%llx) with cpu notes\n",
		 fdh->elfcorehdr_addr);
	fadump_update_elfcore_header(__va(fdh->elfcorehdr_addr));
	return 0;
}

static int __init opal_fadump_process(struct fw_dump *fadump_conf)
{
	struct fadump_crash_info_header *fdh;
	int rc = -EINVAL;

	if (!opal_fdm_active || !fadump_conf->fadumphdr_addr)
		return rc;

	/* Validate the fadump crash info header */
	fdh = __va(fadump_conf->fadumphdr_addr);
	if (fdh->magic_number != FADUMP_CRASH_INFO_MAGIC) {
		pr_err("Crash info header is not valid.\n");
		return rc;
	}

#ifdef CONFIG_OPAL_CORE
	/*
	 * If this is a kernel initiated crash, crashing_cpu would be set
	 * appropriately and register data of the crashing CPU saved by
	 * crashing kernel. Add this saved register data of crashing CPU
	 * to elf notes and populate the pt_regs for the remaining CPUs
	 * from register state data provided by firmware.
	 */
	if (fdh->crashing_cpu != FADUMP_CPU_UNKNOWN)
		kernel_initiated = true;
#endif

	rc = opal_fadump_build_cpu_notes(fadump_conf, fdh);
	if (rc)
		return rc;

	/*
	 * We are done validating dump info and elfcore header is now ready
	 * to be exported. set elfcorehdr_addr so that vmcore module will
	 * export the elfcore header through '/proc/vmcore'.
	 */
	elfcorehdr_addr = fdh->elfcorehdr_addr;

	return rc;
}

static void opal_fadump_region_show(struct fw_dump *fadump_conf,
				    struct seq_file *m)
{
	const struct opal_fadump_mem_struct *fdm_ptr;
	u64 dumped_bytes = 0;
	int i;

	if (fadump_conf->dump_active)
		fdm_ptr = opal_fdm_active;
	else
		fdm_ptr = opal_fdm;

	for (i = 0; i < be16_to_cpu(fdm_ptr->region_cnt); i++) {
		/*
		 * Only regions that are registered for MPIPL
		 * would have dump data.
		 */
		if ((fadump_conf->dump_active) &&
		    (i < be16_to_cpu(fdm_ptr->registered_regions)))
			dumped_bytes = be64_to_cpu(fdm_ptr->rgn[i].size);

		seq_printf(m, "DUMP: Src: %#016llx, Dest: %#016llx, ",
			   be64_to_cpu(fdm_ptr->rgn[i].src),
			   be64_to_cpu(fdm_ptr->rgn[i].dest));
		seq_printf(m, "Size: %#llx, Dumped: %#llx bytes\n",
			   be64_to_cpu(fdm_ptr->rgn[i].size), dumped_bytes);
	}

	/* Dump is active. Show preserved area start address. */
	if (fadump_conf->dump_active) {
		seq_printf(m, "\nMemory above %#016llx is reserved for saving crash dump\n",
			   fadump_conf->boot_mem_top);
	}
}

static void opal_fadump_trigger(struct fadump_crash_info_header *fdh,
				const char *msg)
{
	int rc;

	/*
	 * Unlike on pSeries platform, logical CPU number is not provided
	 * with architected register state data. So, store the crashing
	 * CPU's PIR instead to plug the appropriate register data for
	 * crashing CPU in the vmcore file.
	 */
	fdh->crashing_cpu = (u32)mfspr(SPRN_PIR);

	rc = opal_cec_reboot2(OPAL_REBOOT_MPIPL, msg);
	if (rc == OPAL_UNSUPPORTED) {
		pr_emerg("Reboot type %d not supported.\n",
			 OPAL_REBOOT_MPIPL);
	} else if (rc == OPAL_HARDWARE)
		pr_emerg("No backend support for MPIPL!\n");
}

static struct fadump_ops opal_fadump_ops = {
	.fadump_init_mem_struct		= opal_fadump_init_mem_struct,
	.fadump_get_metadata_size	= opal_fadump_get_metadata_size,
	.fadump_setup_metadata		= opal_fadump_setup_metadata,
	.fadump_get_bootmem_min		= opal_fadump_get_bootmem_min,
	.fadump_register		= opal_fadump_register,
	.fadump_unregister		= opal_fadump_unregister,
	.fadump_invalidate		= opal_fadump_invalidate,
	.fadump_cleanup			= opal_fadump_cleanup,
	.fadump_process			= opal_fadump_process,
	.fadump_region_show		= opal_fadump_region_show,
	.fadump_trigger			= opal_fadump_trigger,
};

void __init opal_fadump_dt_scan(struct fw_dump *fadump_conf, u64 node)
{
	const __be32 *prop;
	unsigned long dn;
	__be64 be_addr;
	u64 addr = 0;
	int i, len;
	s64 ret;

	/*
	 * Check if Firmware-Assisted Dump is supported. if yes, check
	 * if dump has been initiated on last reboot.
	 */
	dn = of_get_flat_dt_subnode_by_name(node, "dump");
	if (dn == -FDT_ERR_NOTFOUND) {
		pr_debug("FADump support is missing!\n");
		return;
	}

	if (!of_flat_dt_is_compatible(dn, "ibm,opal-dump")) {
		pr_err("Support missing for this f/w version!\n");
		return;
	}

	prop = of_get_flat_dt_prop(dn, "fw-load-area", &len);
	if (prop) {
		/*
		 * Each f/w load area is an (address,size) pair,
		 * 2 cells each, totalling 4 cells per range.
		 */
		for (i = 0; i < len / (sizeof(*prop) * 4); i++) {
			u64 base, end;

			base = of_read_number(prop + (i * 4) + 0, 2);
			end = base;
			end += of_read_number(prop + (i * 4) + 2, 2);
			if (end > OPAL_FADUMP_MIN_BOOT_MEM) {
				pr_err("F/W load area: 0x%llx-0x%llx\n",
				       base, end);
				pr_err("F/W version not supported!\n");
				return;
			}
		}
	}

	fadump_conf->ops		= &opal_fadump_ops;
	fadump_conf->fadump_supported	= 1;

	/*
	 * Firmware supports 32-bit field for size. Align it to PAGE_SIZE
	 * and request firmware to copy multiple kernel boot memory regions.
	 */
	fadump_conf->max_copy_size = ALIGN_DOWN(U32_MAX, PAGE_SIZE);

	/*
	 * Check if dump has been initiated on last reboot.
	 */
	prop = of_get_flat_dt_prop(dn, "mpipl-boot", NULL);
	if (!prop)
		return;

	ret = opal_mpipl_query_tag(OPAL_MPIPL_TAG_KERNEL, &be_addr);
	if ((ret != OPAL_SUCCESS) || !be_addr) {
		pr_err("Failed to get Kernel metadata (%lld)\n", ret);
		return;
	}

	addr = be64_to_cpu(be_addr);
	pr_debug("Kernel metadata addr: %llx\n", addr);

	opal_fdm_active = __va(addr);
	if (opal_fdm_active->version != OPAL_FADUMP_VERSION) {
		pr_warn("Supported kernel metadata version: %u, found: %d!\n",
			OPAL_FADUMP_VERSION, opal_fdm_active->version);
		pr_warn("WARNING: Kernel metadata format mismatch identified! Core file maybe corrupted..\n");
	}

	/* Kernel regions not registered with f/w for MPIPL */
	if (be16_to_cpu(opal_fdm_active->registered_regions) == 0) {
		opal_fdm_active = NULL;
		return;
	}

	ret = opal_mpipl_query_tag(OPAL_MPIPL_TAG_CPU, &be_addr);
	if (be_addr) {
		addr = be64_to_cpu(be_addr);
		pr_debug("CPU metadata addr: %llx\n", addr);
		opal_cpu_metadata = __va(addr);
	}

	pr_info("Firmware-assisted dump is active.\n");
	fadump_conf->dump_active = 1;
	opal_fadump_get_config(fadump_conf, opal_fdm_active);
}
#endif /* !CONFIG_PRESERVE_FA_DUMP */