Adding upstream version 5.10.209.upstream/5.10.209

Signed-off-by: Daniel Baumann <daniel.baumann@progress-linux.org>

1 files changed, 1719 insertions, 0 deletions

diff --git a/arch/powerpc/kernel/fadump.c b/arch/powerpc/kernel/fadump.c
new file mode 100644
index 000000000..935ce1bec
--- /dev/null
+++ b/arch/powerpc/kernel/fadump.c
@@ -0,0 +1,1719 @@
+// SPDX-License-Identifier: GPL-2.0-or-later
+/*
+ * Firmware Assisted dump: A robust mechanism to get reliable kernel crash
+ * dump with assistance from firmware. This approach does not use kexec,
+ * instead firmware assists in booting the kdump kernel while preserving
+ * memory contents. The most of the code implementation has been adapted
+ * from phyp assisted dump implementation written by Linas Vepstas and
+ * Manish Ahuja
+ *
+ * Copyright 2011 IBM Corporation
+ * Author: Mahesh Salgaonkar <mahesh@linux.vnet.ibm.com>
+ */
+
+#undef DEBUG
+#define pr_fmt(fmt) "fadump: " fmt
+
+#include <linux/string.h>
+#include <linux/memblock.h>
+#include <linux/delay.h>
+#include <linux/seq_file.h>
+#include <linux/crash_dump.h>
+#include <linux/kobject.h>
+#include <linux/sysfs.h>
+#include <linux/slab.h>
+#include <linux/cma.h>
+#include <linux/hugetlb.h>
+
+#include <asm/debugfs.h>
+#include <asm/page.h>
+#include <asm/prom.h>
+#include <asm/fadump.h>
+#include <asm/fadump-internal.h>
+#include <asm/setup.h>
+
+/*
+ * The CPU who acquired the lock to trigger the fadump crash should
+ * wait for other CPUs to enter.
+ *
+ * The timeout is in milliseconds.
+ */
+#define CRASH_TIMEOUT		500
+
+static struct fw_dump fw_dump;
+
+static void __init fadump_reserve_crash_area(u64 base);
+
+struct kobject *fadump_kobj;
+
+#ifndef CONFIG_PRESERVE_FA_DUMP
+
+static atomic_t cpus_in_fadump;
+static DEFINE_MUTEX(fadump_mutex);
+
+struct fadump_mrange_info crash_mrange_info = { "crash", NULL, 0, 0, 0, false };
+
+#define RESERVED_RNGS_SZ	16384 /* 16K - 128 entries */
+#define RESERVED_RNGS_CNT	(RESERVED_RNGS_SZ / \
+				 sizeof(struct fadump_memory_range))
+static struct fadump_memory_range rngs[RESERVED_RNGS_CNT];
+struct fadump_mrange_info reserved_mrange_info = { "reserved", rngs,
+						   RESERVED_RNGS_SZ, 0,
+						   RESERVED_RNGS_CNT, true };
+
+static void __init early_init_dt_scan_reserved_ranges(unsigned long node);
+
+#ifdef CONFIG_CMA
+static struct cma *fadump_cma;
+
+/*
+ * fadump_cma_init() - Initialize CMA area from a fadump reserved memory
+ *
+ * This function initializes CMA area from fadump reserved memory.
+ * The total size of fadump reserved memory covers for boot memory size
+ * + cpu data size + hpte size and metadata.
+ * Initialize only the area equivalent to boot memory size for CMA use.
+ * The reamining portion of fadump reserved memory will be not given
+ * to CMA and pages for thoes will stay reserved. boot memory size is
+ * aligned per CMA requirement to satisy cma_init_reserved_mem() call.
+ * But for some reason even if it fails we still have the memory reservation
+ * with us and we can still continue doing fadump.
+ */
+int __init fadump_cma_init(void)
+{
+	unsigned long long base, size;
+	int rc;
+
+	if (!fw_dump.fadump_enabled)
+		return 0;
+
+	/*
+	 * Do not use CMA if user has provided fadump=nocma kernel parameter.
+	 * Return 1 to continue with fadump old behaviour.
+	 */
+	if (fw_dump.nocma)
+		return 1;
+
+	base = fw_dump.reserve_dump_area_start;
+	size = fw_dump.boot_memory_size;
+
+	if (!size)
+		return 0;
+
+	rc = cma_init_reserved_mem(base, size, 0, "fadump_cma", &fadump_cma);
+	if (rc) {
+		pr_err("Failed to init cma area for firmware-assisted dump,%d\n", rc);
+		/*
+		 * Though the CMA init has failed we still have memory
+		 * reservation with us. The reserved memory will be
+		 * blocked from production system usage.  Hence return 1,
+		 * so that we can continue with fadump.
+		 */
+		return 1;
+	}
+
+	/*
+	 * So we now have successfully initialized cma area for fadump.
+	 */
+	pr_info("Initialized 0x%lx bytes cma area at %ldMB from 0x%lx "
+		"bytes of memory reserved for firmware-assisted dump\n",
+		cma_get_size(fadump_cma),
+		(unsigned long)cma_get_base(fadump_cma) >> 20,
+		fw_dump.reserve_dump_area_size);
+	return 1;
+}
+#else
+static int __init fadump_cma_init(void) { return 1; }
+#endif /* CONFIG_CMA */
+
+/* Scan the Firmware Assisted dump configuration details. */
+int __init early_init_dt_scan_fw_dump(unsigned long node, const char *uname,
+				      int depth, void *data)
+{
+	if (depth == 0) {
+		early_init_dt_scan_reserved_ranges(node);
+		return 0;
+	}
+
+	if (depth != 1)
+		return 0;
+
+	if (strcmp(uname, "rtas") == 0) {
+		rtas_fadump_dt_scan(&fw_dump, node);
+		return 1;
+	}
+
+	if (strcmp(uname, "ibm,opal") == 0) {
+		opal_fadump_dt_scan(&fw_dump, node);
+		return 1;
+	}
+
+	return 0;
+}
+
+/*
+ * If fadump is registered, check if the memory provided
+ * falls within boot memory area and reserved memory area.
+ */
+int is_fadump_memory_area(u64 addr, unsigned long size)
+{
+	u64 d_start, d_end;
+
+	if (!fw_dump.dump_registered)
+		return 0;
+
+	if (!size)
+		return 0;
+
+	d_start = fw_dump.reserve_dump_area_start;
+	d_end = d_start + fw_dump.reserve_dump_area_size;
+	if (((addr + size) > d_start) && (addr <= d_end))
+		return 1;
+
+	return (addr <= fw_dump.boot_mem_top);
+}
+
+int should_fadump_crash(void)
+{
+	if (!fw_dump.dump_registered || !fw_dump.fadumphdr_addr)
+		return 0;
+	return 1;
+}
+
+int is_fadump_active(void)
+{
+	return fw_dump.dump_active;
+}
+
+/*
+ * Returns true, if there are no holes in memory area between d_start to d_end,
+ * false otherwise.
+ */
+static bool is_fadump_mem_area_contiguous(u64 d_start, u64 d_end)
+{
+	phys_addr_t reg_start, reg_end;
+	bool ret = false;
+	u64 i, start, end;
+
+	for_each_mem_range(i, &reg_start, &reg_end) {
+		start = max_t(u64, d_start, reg_start);
+		end = min_t(u64, d_end, reg_end);
+		if (d_start < end) {
+			/* Memory hole from d_start to start */
+			if (start > d_start)
+				break;
+
+			if (end == d_end) {
+				ret = true;
+				break;
+			}
+
+			d_start = end + 1;
+		}
+	}
+
+	return ret;
+}
+
+/*
+ * Returns true, if there are no holes in boot memory area,
+ * false otherwise.
+ */
+bool is_fadump_boot_mem_contiguous(void)
+{
+	unsigned long d_start, d_end;
+	bool ret = false;
+	int i;
+
+	for (i = 0; i < fw_dump.boot_mem_regs_cnt; i++) {
+		d_start = fw_dump.boot_mem_addr[i];
+		d_end   = d_start + fw_dump.boot_mem_sz[i];
+
+		ret = is_fadump_mem_area_contiguous(d_start, d_end);
+		if (!ret)
+			break;
+	}
+
+	return ret;
+}
+
+/*
+ * Returns true, if there are no holes in reserved memory area,
+ * false otherwise.
+ */
+bool is_fadump_reserved_mem_contiguous(void)
+{
+	u64 d_start, d_end;
+
+	d_start	= fw_dump.reserve_dump_area_start;
+	d_end	= d_start + fw_dump.reserve_dump_area_size;
+	return is_fadump_mem_area_contiguous(d_start, d_end);
+}
+
+/* Print firmware assisted dump configurations for debugging purpose. */
+static void fadump_show_config(void)
+{
+	int i;
+
+	pr_debug("Support for firmware-assisted dump (fadump): %s\n",
+			(fw_dump.fadump_supported ? "present" : "no support"));
+
+	if (!fw_dump.fadump_supported)
+		return;
+
+	pr_debug("Fadump enabled    : %s\n",
+				(fw_dump.fadump_enabled ? "yes" : "no"));
+	pr_debug("Dump Active       : %s\n",
+				(fw_dump.dump_active ? "yes" : "no"));
+	pr_debug("Dump section sizes:\n");
+	pr_debug("    CPU state data size: %lx\n", fw_dump.cpu_state_data_size);
+	pr_debug("    HPTE region size   : %lx\n", fw_dump.hpte_region_size);
+	pr_debug("    Boot memory size   : %lx\n", fw_dump.boot_memory_size);
+	pr_debug("    Boot memory top    : %llx\n", fw_dump.boot_mem_top);
+	pr_debug("Boot memory regions cnt: %llx\n", fw_dump.boot_mem_regs_cnt);
+	for (i = 0; i < fw_dump.boot_mem_regs_cnt; i++) {
+		pr_debug("[%03d] base = %llx, size = %llx\n", i,
+			 fw_dump.boot_mem_addr[i], fw_dump.boot_mem_sz[i]);
+	}
+}
+
+/**
+ * fadump_calculate_reserve_size(): reserve variable boot area 5% of System RAM
+ *
+ * Function to find the largest memory size we need to reserve during early
+ * boot process. This will be the size of the memory that is required for a
+ * kernel to boot successfully.
+ *
+ * This function has been taken from phyp-assisted dump feature implementation.
+ *
+ * returns larger of 256MB or 5% rounded down to multiples of 256MB.
+ *
+ * TODO: Come up with better approach to find out more accurate memory size
+ * that is required for a kernel to boot successfully.
+ *
+ */
+static __init u64 fadump_calculate_reserve_size(void)
+{
+	u64 base, size, bootmem_min;
+	int ret;
+
+	if (fw_dump.reserve_bootvar)
+		pr_warn("'fadump_reserve_mem=' parameter is deprecated in favor of 'crashkernel=' parameter.\n");
+
+	/*
+	 * Check if the size is specified through crashkernel= cmdline
+	 * option. If yes, then use that but ignore base as fadump reserves
+	 * memory at a predefined offset.
+	 */
+	ret = parse_crashkernel(boot_command_line, memblock_phys_mem_size(),
+				&size, &base);
+	if (ret == 0 && size > 0) {
+		unsigned long max_size;
+
+		if (fw_dump.reserve_bootvar)
+			pr_info("Using 'crashkernel=' parameter for memory reservation.\n");
+
+		fw_dump.reserve_bootvar = (unsigned long)size;
+
+		/*
+		 * Adjust if the boot memory size specified is above
+		 * the upper limit.
+		 */
+		max_size = memblock_phys_mem_size() / MAX_BOOT_MEM_RATIO;
+		if (fw_dump.reserve_bootvar > max_size) {
+			fw_dump.reserve_bootvar = max_size;
+			pr_info("Adjusted boot memory size to %luMB\n",
+				(fw_dump.reserve_bootvar >> 20));
+		}
+
+		return fw_dump.reserve_bootvar;
+	} else if (fw_dump.reserve_bootvar) {
+		/*
+		 * 'fadump_reserve_mem=' is being used to reserve memory
+		 * for firmware-assisted dump.
+		 */
+		return fw_dump.reserve_bootvar;
+	}
+
+	/* divide by 20 to get 5% of value */
+	size = memblock_phys_mem_size() / 20;
+
+	/* round it down in multiples of 256 */
+	size = size & ~0x0FFFFFFFUL;
+
+	/* Truncate to memory_limit. We don't want to over reserve the memory.*/
+	if (memory_limit && size > memory_limit)
+		size = memory_limit;
+
+	bootmem_min = fw_dump.ops->fadump_get_bootmem_min();
+	return (size > bootmem_min ? size : bootmem_min);
+}
+
+/*
+ * Calculate the total memory size required to be reserved for
+ * firmware-assisted dump registration.
+ */
+static unsigned long get_fadump_area_size(void)
+{
+	unsigned long size = 0;
+
+	size += fw_dump.cpu_state_data_size;
+	size += fw_dump.hpte_region_size;
+	size += fw_dump.boot_memory_size;
+	size += sizeof(struct fadump_crash_info_header);
+	size += sizeof(struct elfhdr); /* ELF core header.*/
+	size += sizeof(struct elf_phdr); /* place holder for cpu notes */
+	/* Program headers for crash memory regions. */
+	size += sizeof(struct elf_phdr) * (memblock_num_regions(memory) + 2);
+
+	size = PAGE_ALIGN(size);
+
+	/* This is to hold kernel metadata on platforms that support it */
+	size += (fw_dump.ops->fadump_get_metadata_size ?
+		 fw_dump.ops->fadump_get_metadata_size() : 0);
+	return size;
+}
+
+static int __init add_boot_mem_region(unsigned long rstart,
+				      unsigned long rsize)
+{
+	int i = fw_dump.boot_mem_regs_cnt++;
+
+	if (fw_dump.boot_mem_regs_cnt > FADUMP_MAX_MEM_REGS) {
+		fw_dump.boot_mem_regs_cnt = FADUMP_MAX_MEM_REGS;
+		return 0;
+	}
+
+	pr_debug("Added boot memory range[%d] [%#016lx-%#016lx)\n",
+		 i, rstart, (rstart + rsize));
+	fw_dump.boot_mem_addr[i] = rstart;
+	fw_dump.boot_mem_sz[i] = rsize;
+	return 1;
+}
+
+/*
+ * Firmware usually has a hard limit on the data it can copy per region.
+ * Honour that by splitting a memory range into multiple regions.
+ */
+static int __init add_boot_mem_regions(unsigned long mstart,
+				       unsigned long msize)
+{
+	unsigned long rstart, rsize, max_size;
+	int ret = 1;
+
+	rstart = mstart;
+	max_size = fw_dump.max_copy_size ? fw_dump.max_copy_size : msize;
+	while (msize) {
+		if (msize > max_size)
+			rsize = max_size;
+		else
+			rsize = msize;
+
+		ret = add_boot_mem_region(rstart, rsize);
+		if (!ret)
+			break;
+
+		msize -= rsize;
+		rstart += rsize;
+	}
+
+	return ret;
+}
+
+static int __init fadump_get_boot_mem_regions(void)
+{
+	unsigned long size, cur_size, hole_size, last_end;
+	unsigned long mem_size = fw_dump.boot_memory_size;
+	phys_addr_t reg_start, reg_end;
+	int ret = 1;
+	u64 i;
+
+	fw_dump.boot_mem_regs_cnt = 0;
+
+	last_end = 0;
+	hole_size = 0;
+	cur_size = 0;
+	for_each_mem_range(i, &reg_start, &reg_end) {
+		size = reg_end - reg_start;
+		hole_size += (reg_start - last_end);
+
+		if ((cur_size + size) >= mem_size) {
+			size = (mem_size - cur_size);
+			ret = add_boot_mem_regions(reg_start, size);
+			break;
+		}
+
+		mem_size -= size;
+		cur_size += size;
+		ret = add_boot_mem_regions(reg_start, size);
+		if (!ret)
+			break;
+
+		last_end = reg_end;
+	}
+	fw_dump.boot_mem_top = PAGE_ALIGN(fw_dump.boot_memory_size + hole_size);
+
+	return ret;
+}
+
+/*
+ * Returns true, if the given range overlaps with reserved memory ranges
+ * starting at idx. Also, updates idx to index of overlapping memory range
+ * with the given memory range.
+ * False, otherwise.
+ */
+static bool overlaps_reserved_ranges(u64 base, u64 end, int *idx)
+{
+	bool ret = false;
+	int i;
+
+	for (i = *idx; i < reserved_mrange_info.mem_range_cnt; i++) {
+		u64 rbase = reserved_mrange_info.mem_ranges[i].base;
+		u64 rend = rbase + reserved_mrange_info.mem_ranges[i].size;
+
+		if (end <= rbase)
+			break;
+
+		if ((end > rbase) &&  (base < rend)) {
+			*idx = i;
+			ret = true;
+			break;
+		}
+	}
+
+	return ret;
+}
+
+/*
+ * Locate a suitable memory area to reserve memory for FADump. While at it,
+ * lookup reserved-ranges & avoid overlap with them, as they are used by F/W.
+ */
+static u64 __init fadump_locate_reserve_mem(u64 base, u64 size)
+{
+	struct fadump_memory_range *mrngs;
+	phys_addr_t mstart, mend;
+	int idx = 0;
+	u64 i, ret = 0;
+
+	mrngs = reserved_mrange_info.mem_ranges;
+	for_each_free_mem_range(i, NUMA_NO_NODE, MEMBLOCK_NONE,
+				&mstart, &mend, NULL) {
+		pr_debug("%llu) mstart: %llx, mend: %llx, base: %llx\n",
+			 i, mstart, mend, base);
+
+		if (mstart > base)
+			base = PAGE_ALIGN(mstart);
+
+		while ((mend > base) && ((mend - base) >= size)) {
+			if (!overlaps_reserved_ranges(base, base+size, &idx)) {
+				ret = base;
+				goto out;
+			}
+
+			base = mrngs[idx].base + mrngs[idx].size;
+			base = PAGE_ALIGN(base);
+		}
+	}
+
+out:
+	return ret;
+}
+
+int __init fadump_reserve_mem(void)
+{
+	u64 base, size, mem_boundary, bootmem_min;
+	int ret = 1;
+
+	if (!fw_dump.fadump_enabled)
+		return 0;
+
+	if (!fw_dump.fadump_supported) {
+		pr_info("Firmware-Assisted Dump is not supported on this hardware\n");
+		goto error_out;
+	}
+
+	/*
+	 * Initialize boot memory size
+	 * If dump is active then we have already calculated the size during
+	 * first kernel.
+	 */
+	if (!fw_dump.dump_active) {
+		fw_dump.boot_memory_size =
+			PAGE_ALIGN(fadump_calculate_reserve_size());
+#ifdef CONFIG_CMA
+		if (!fw_dump.nocma) {
+			fw_dump.boot_memory_size =
+				ALIGN(fw_dump.boot_memory_size,
+				      FADUMP_CMA_ALIGNMENT);
+		}
+#endif
+
+		bootmem_min = fw_dump.ops->fadump_get_bootmem_min();
+		if (fw_dump.boot_memory_size < bootmem_min) {
+			pr_err("Can't enable fadump with boot memory size (0x%lx) less than 0x%llx\n",
+			       fw_dump.boot_memory_size, bootmem_min);
+			goto error_out;
+		}
+
+		if (!fadump_get_boot_mem_regions()) {
+			pr_err("Too many holes in boot memory area to enable fadump\n");
+			goto error_out;
+		}
+	}
+
+	/*
+	 * Calculate the memory boundary.
+	 * If memory_limit is less than actual memory boundary then reserve
+	 * the memory for fadump beyond the memory_limit and adjust the
+	 * memory_limit accordingly, so that the running kernel can run with
+	 * specified memory_limit.
+	 */
+	if (memory_limit && memory_limit < memblock_end_of_DRAM()) {
+		size = get_fadump_area_size();
+		if ((memory_limit + size) < memblock_end_of_DRAM())
+			memory_limit += size;
+		else
+			memory_limit = memblock_end_of_DRAM();
+		printk(KERN_INFO "Adjusted memory_limit for firmware-assisted"
+				" dump, now %#016llx\n", memory_limit);
+	}
+	if (memory_limit)
+		mem_boundary = memory_limit;
+	else
+		mem_boundary = memblock_end_of_DRAM();
+
+	base = fw_dump.boot_mem_top;
+	size = get_fadump_area_size();
+	fw_dump.reserve_dump_area_size = size;
+	if (fw_dump.dump_active) {
+		pr_info("Firmware-assisted dump is active.\n");
+
+#ifdef CONFIG_HUGETLB_PAGE
+		/*
+		 * FADump capture kernel doesn't care much about hugepages.
+		 * In fact, handling hugepages in capture kernel is asking for
+		 * trouble. So, disable HugeTLB support when fadump is active.
+		 */
+		hugetlb_disabled = true;
+#endif
+		/*
+		 * If last boot has crashed then reserve all the memory
+		 * above boot memory size so that we don't touch it until
+		 * dump is written to disk by userspace tool. This memory
+		 * can be released for general use by invalidating fadump.
+		 */
+		fadump_reserve_crash_area(base);
+
+		pr_debug("fadumphdr_addr = %#016lx\n", fw_dump.fadumphdr_addr);
+		pr_debug("Reserve dump area start address: 0x%lx\n",
+			 fw_dump.reserve_dump_area_start);
+	} else {
+		/*
+		 * Reserve memory at an offset closer to bottom of the RAM to
+		 * minimize the impact of memory hot-remove operation.
+		 */
+		base = fadump_locate_reserve_mem(base, size);
+
+		if (!base || (base + size > mem_boundary)) {
+			pr_err("Failed to find memory chunk for reservation!\n");
+			goto error_out;
+		}
+		fw_dump.reserve_dump_area_start = base;
+
+		/*
+		 * Calculate the kernel metadata address and register it with
+		 * f/w if the platform supports.
+		 */
+		if (fw_dump.ops->fadump_setup_metadata &&
+		    (fw_dump.ops->fadump_setup_metadata(&fw_dump) < 0))
+			goto error_out;
+
+		if (memblock_reserve(base, size)) {
+			pr_err("Failed to reserve memory!\n");
+			goto error_out;
+		}
+
+		pr_info("Reserved %lldMB of memory at %#016llx (System RAM: %lldMB)\n",
+			(size >> 20), base, (memblock_phys_mem_size() >> 20));
+
+		ret = fadump_cma_init();
+	}
+
+	return ret;
+error_out:
+	fw_dump.fadump_enabled = 0;
+	fw_dump.reserve_dump_area_size = 0;
+	return 0;
+}
+
+/* Look for fadump= cmdline option. */
+static int __init early_fadump_param(char *p)
+{
+	if (!p)
+		return 1;
+
+	if (strncmp(p, "on", 2) == 0)
+		fw_dump.fadump_enabled = 1;
+	else if (strncmp(p, "off", 3) == 0)
+		fw_dump.fadump_enabled = 0;
+	else if (strncmp(p, "nocma", 5) == 0) {
+		fw_dump.fadump_enabled = 1;
+		fw_dump.nocma = 1;
+	}
+
+	return 0;
+}
+early_param("fadump", early_fadump_param);
+
+/*
+ * Look for fadump_reserve_mem= cmdline option
+ * TODO: Remove references to 'fadump_reserve_mem=' parameter,
+ *       the sooner 'crashkernel=' parameter is accustomed to.
+ */
+static int __init early_fadump_reserve_mem(char *p)
+{
+	if (p)
+		fw_dump.reserve_bootvar = memparse(p, &p);
+	return 0;
+}
+early_param("fadump_reserve_mem", early_fadump_reserve_mem);
+
+void crash_fadump(struct pt_regs *regs, const char *str)
+{
+	unsigned int msecs;
+	struct fadump_crash_info_header *fdh = NULL;
+	int old_cpu, this_cpu;
+	/* Do not include first CPU */
+	unsigned int ncpus = num_online_cpus() - 1;
+
+	if (!should_fadump_crash())
+		return;
+
+	/*
+	 * old_cpu == -1 means this is the first CPU which has come here,
+	 * go ahead and trigger fadump.
+	 *
+	 * old_cpu != -1 means some other CPU has already on it's way
+	 * to trigger fadump, just keep looping here.
+	 */
+	this_cpu = smp_processor_id();
+	old_cpu = cmpxchg(&crashing_cpu, -1, this_cpu);
+
+	if (old_cpu != -1) {
+		atomic_inc(&cpus_in_fadump);
+
+		/*
+		 * We can't loop here indefinitely. Wait as long as fadump
+		 * is in force. If we race with fadump un-registration this
+		 * loop will break and then we go down to normal panic path
+		 * and reboot. If fadump is in force the first crashing
+		 * cpu will definitely trigger fadump.
+		 */
+		while (fw_dump.dump_registered)
+			cpu_relax();
+		return;
+	}
+
+	fdh = __va(fw_dump.fadumphdr_addr);
+	fdh->crashing_cpu = crashing_cpu;
+	crash_save_vmcoreinfo();
+
+	if (regs)
+		fdh->regs = *regs;
+	else
+		ppc_save_regs(&fdh->regs);
+
+	fdh->online_mask = *cpu_online_mask;
+
+	/*
+	 * If we came in via system reset, wait a while for the secondary
+	 * CPUs to enter.
+	 */
+	if (TRAP(&(fdh->regs)) == 0x100) {
+		msecs = CRASH_TIMEOUT;
+		while ((atomic_read(&cpus_in_fadump) < ncpus) && (--msecs > 0))
+			mdelay(1);
+	}
+
+	fw_dump.ops->fadump_trigger(fdh, str);
+}
+
+u32 *fadump_regs_to_elf_notes(u32 *buf, struct pt_regs *regs)
+{
+	struct elf_prstatus prstatus;
+
+	memset(&prstatus, 0, sizeof(prstatus));
+	/*
+	 * FIXME: How do i get PID? Do I really need it?
+	 * prstatus.pr_pid = ????
+	 */
+	elf_core_copy_kernel_regs(&prstatus.pr_reg, regs);
+	buf = append_elf_note(buf, CRASH_CORE_NOTE_NAME, NT_PRSTATUS,
+			      &prstatus, sizeof(prstatus));
+	return buf;
+}
+
+void fadump_update_elfcore_header(char *bufp)
+{
+	struct elf_phdr *phdr;
+
+	bufp += sizeof(struct elfhdr);
+
+	/* First note is a place holder for cpu notes info. */
+	phdr = (struct elf_phdr *)bufp;
+
+	if (phdr->p_type == PT_NOTE) {
+		phdr->p_paddr	= __pa(fw_dump.cpu_notes_buf_vaddr);
+		phdr->p_offset	= phdr->p_paddr;
+		phdr->p_filesz	= fw_dump.cpu_notes_buf_size;
+		phdr->p_memsz = fw_dump.cpu_notes_buf_size;
+	}
+	return;
+}
+
+static void *fadump_alloc_buffer(unsigned long size)
+{
+	unsigned long count, i;
+	struct page *page;
+	void *vaddr;
+
+	vaddr = alloc_pages_exact(size, GFP_KERNEL | __GFP_ZERO);
+	if (!vaddr)
+		return NULL;
+
+	count = PAGE_ALIGN(size) / PAGE_SIZE;
+	page = virt_to_page(vaddr);
+	for (i = 0; i < count; i++)
+		mark_page_reserved(page + i);
+	return vaddr;
+}
+
+static void fadump_free_buffer(unsigned long vaddr, unsigned long size)
+{
+	free_reserved_area((void *)vaddr, (void *)(vaddr + size), -1, NULL);
+}
+
+s32 fadump_setup_cpu_notes_buf(u32 num_cpus)
+{
+	/* Allocate buffer to hold cpu crash notes. */
+	fw_dump.cpu_notes_buf_size = num_cpus * sizeof(note_buf_t);
+	fw_dump.cpu_notes_buf_size = PAGE_ALIGN(fw_dump.cpu_notes_buf_size);
+	fw_dump.cpu_notes_buf_vaddr =
+		(unsigned long)fadump_alloc_buffer(fw_dump.cpu_notes_buf_size);
+	if (!fw_dump.cpu_notes_buf_vaddr) {
+		pr_err("Failed to allocate %ld bytes for CPU notes buffer\n",
+		       fw_dump.cpu_notes_buf_size);
+		return -ENOMEM;
+	}
+
+	pr_debug("Allocated buffer for cpu notes of size %ld at 0x%lx\n",
+		 fw_dump.cpu_notes_buf_size,
+		 fw_dump.cpu_notes_buf_vaddr);
+	return 0;
+}
+
+void fadump_free_cpu_notes_buf(void)
+{
+	if (!fw_dump.cpu_notes_buf_vaddr)
+		return;
+
+	fadump_free_buffer(fw_dump.cpu_notes_buf_vaddr,
+			   fw_dump.cpu_notes_buf_size);
+	fw_dump.cpu_notes_buf_vaddr = 0;
+	fw_dump.cpu_notes_buf_size = 0;
+}
+
+static void fadump_free_mem_ranges(struct fadump_mrange_info *mrange_info)
+{
+	if (mrange_info->is_static) {
+		mrange_info->mem_range_cnt = 0;
+		return;
+	}
+
+	kfree(mrange_info->mem_ranges);
+	memset((void *)((u64)mrange_info + RNG_NAME_SZ), 0,
+	       (sizeof(struct fadump_mrange_info) - RNG_NAME_SZ));
+}
+
+/*
+ * Allocate or reallocate mem_ranges array in incremental units
+ * of PAGE_SIZE.
+ */
+static int fadump_alloc_mem_ranges(struct fadump_mrange_info *mrange_info)
+{
+	struct fadump_memory_range *new_array;
+	u64 new_size;
+
+	new_size = mrange_info->mem_ranges_sz + PAGE_SIZE;
+	pr_debug("Allocating %llu bytes of memory for %s memory ranges\n",
+		 new_size, mrange_info->name);
+
+	new_array = krealloc(mrange_info->mem_ranges, new_size, GFP_KERNEL);
+	if (new_array == NULL) {
+		pr_err("Insufficient memory for setting up %s memory ranges\n",
+		       mrange_info->name);
+		fadump_free_mem_ranges(mrange_info);
+		return -ENOMEM;
+	}
+
+	mrange_info->mem_ranges = new_array;
+	mrange_info->mem_ranges_sz = new_size;
+	mrange_info->max_mem_ranges = (new_size /
+				       sizeof(struct fadump_memory_range));
+	return 0;
+}
+static inline int fadump_add_mem_range(struct fadump_mrange_info *mrange_info,
+				       u64 base, u64 end)
+{
+	struct fadump_memory_range *mem_ranges = mrange_info->mem_ranges;
+	bool is_adjacent = false;
+	u64 start, size;
+
+	if (base == end)
+		return 0;
+
+	/*
+	 * Fold adjacent memory ranges to bring down the memory ranges/
+	 * PT_LOAD segments count.
+	 */
+	if (mrange_info->mem_range_cnt) {
+		start = mem_ranges[mrange_info->mem_range_cnt - 1].base;
+		size  = mem_ranges[mrange_info->mem_range_cnt - 1].size;
+
+		/*
+		 * Boot memory area needs separate PT_LOAD segment(s) as it
+		 * is moved to a different location at the time of crash.
+		 * So, fold only if the region is not boot memory area.
+		 */
+		if ((start + size) == base && start >= fw_dump.boot_mem_top)
+			is_adjacent = true;
+	}
+	if (!is_adjacent) {
+		/* resize the array on reaching the limit */
+		if (mrange_info->mem_range_cnt == mrange_info->max_mem_ranges) {
+			int ret;
+
+			if (mrange_info->is_static) {
+				pr_err("Reached array size limit for %s memory ranges\n",
+				       mrange_info->name);
+				return -ENOSPC;
+			}
+
+			ret = fadump_alloc_mem_ranges(mrange_info);
+			if (ret)
+				return ret;
+
+			/* Update to the new resized array */
+			mem_ranges = mrange_info->mem_ranges;
+		}
+
+		start = base;
+		mem_ranges[mrange_info->mem_range_cnt].base = start;
+		mrange_info->mem_range_cnt++;
+	}
+
+	mem_ranges[mrange_info->mem_range_cnt - 1].size = (end - start);
+	pr_debug("%s_memory_range[%d] [%#016llx-%#016llx], %#llx bytes\n",
+		 mrange_info->name, (mrange_info->mem_range_cnt - 1),
+		 start, end - 1, (end - start));
+	return 0;
+}
+
+static int fadump_exclude_reserved_area(u64 start, u64 end)
+{
+	u64 ra_start, ra_end;
+	int ret = 0;
+
+	ra_start = fw_dump.reserve_dump_area_start;
+	ra_end = ra_start + fw_dump.reserve_dump_area_size;
+
+	if ((ra_start < end) && (ra_end > start)) {
+		if ((start < ra_start) && (end > ra_end)) {
+			ret = fadump_add_mem_range(&crash_mrange_info,
+						   start, ra_start);
+			if (ret)
+				return ret;
+
+			ret = fadump_add_mem_range(&crash_mrange_info,
+						   ra_end, end);
+		} else if (start < ra_start) {
+			ret = fadump_add_mem_range(&crash_mrange_info,
+						   start, ra_start);
+		} else if (ra_end < end) {
+			ret = fadump_add_mem_range(&crash_mrange_info,
+						   ra_end, end);
+		}
+	} else
+		ret = fadump_add_mem_range(&crash_mrange_info, start, end);
+
+	return ret;
+}
+
+static int fadump_init_elfcore_header(char *bufp)
+{
+	struct elfhdr *elf;
+
+	elf = (struct elfhdr *) bufp;
+	bufp += sizeof(struct elfhdr);
+	memcpy(elf->e_ident, ELFMAG, SELFMAG);
+	elf->e_ident[EI_CLASS] = ELF_CLASS;
+	elf->e_ident[EI_DATA] = ELF_DATA;
+	elf->e_ident[EI_VERSION] = EV_CURRENT;
+	elf->e_ident[EI_OSABI] = ELF_OSABI;
+	memset(elf->e_ident+EI_PAD, 0, EI_NIDENT-EI_PAD);
+	elf->e_type = ET_CORE;
+	elf->e_machine = ELF_ARCH;
+	elf->e_version = EV_CURRENT;
+	elf->e_entry = 0;
+	elf->e_phoff = sizeof(struct elfhdr);
+	elf->e_shoff = 0;
+#if defined(_CALL_ELF)
+	elf->e_flags = _CALL_ELF;
+#else
+	elf->e_flags = 0;
+#endif
+	elf->e_ehsize = sizeof(struct elfhdr);
+	elf->e_phentsize = sizeof(struct elf_phdr);
+	elf->e_phnum = 0;
+	elf->e_shentsize = 0;
+	elf->e_shnum = 0;
+	elf->e_shstrndx = 0;
+
+	return 0;
+}
+
+/*
+ * Traverse through memblock structure and setup crash memory ranges. These
+ * ranges will be used create PT_LOAD program headers in elfcore header.
+ */
+static int fadump_setup_crash_memory_ranges(void)
+{
+	u64 i, start, end;
+	int ret;
+
+	pr_debug("Setup crash memory ranges.\n");
+	crash_mrange_info.mem_range_cnt = 0;
+
+	/*
+	 * Boot memory region(s) registered with firmware are moved to
+	 * different location at the time of crash. Create separate program
+	 * header(s) for this memory chunk(s) with the correct offset.
+	 */
+	for (i = 0; i < fw_dump.boot_mem_regs_cnt; i++) {
+		start = fw_dump.boot_mem_addr[i];
+		end = start + fw_dump.boot_mem_sz[i];
+		ret = fadump_add_mem_range(&crash_mrange_info, start, end);
+		if (ret)
+			return ret;
+	}
+
+	for_each_mem_range(i, &start, &end) {
+		/*
+		 * skip the memory chunk that is already added
+		 * (0 through boot_memory_top).
+		 */
+		if (start < fw_dump.boot_mem_top) {
+			if (end > fw_dump.boot_mem_top)
+				start = fw_dump.boot_mem_top;
+			else
+				continue;
+		}
+
+		/* add this range excluding the reserved dump area. */
+		ret = fadump_exclude_reserved_area(start, end);
+		if (ret)
+			return ret;
+	}
+
+	return 0;
+}
+
+/*
+ * If the given physical address falls within the boot memory region then
+ * return the relocated address that points to the dump region reserved
+ * for saving initial boot memory contents.
+ */
+static inline unsigned long fadump_relocate(unsigned long paddr)
+{
+	unsigned long raddr, rstart, rend, rlast, hole_size;
+	int i;
+
+	hole_size = 0;
+	rlast = 0;
+	raddr = paddr;
+	for (i = 0; i < fw_dump.boot_mem_regs_cnt; i++) {
+		rstart = fw_dump.boot_mem_addr[i];
+		rend = rstart + fw_dump.boot_mem_sz[i];
+		hole_size += (rstart - rlast);
+
+		if (paddr >= rstart && paddr < rend) {
+			raddr += fw_dump.boot_mem_dest_addr - hole_size;
+			break;
+		}
+
+		rlast = rend;
+	}
+
+	pr_debug("vmcoreinfo: paddr = 0x%lx, raddr = 0x%lx\n", paddr, raddr);
+	return raddr;
+}
+
+static int fadump_create_elfcore_headers(char *bufp)
+{
+	unsigned long long raddr, offset;
+	struct elf_phdr *phdr;
+	struct elfhdr *elf;
+	int i, j;
+
+	fadump_init_elfcore_header(bufp);
+	elf = (struct elfhdr *)bufp;
+	bufp += sizeof(struct elfhdr);
+
+	/*
+	 * setup ELF PT_NOTE, place holder for cpu notes info. The notes info
+	 * will be populated during second kernel boot after crash. Hence
+	 * this PT_NOTE will always be the first elf note.
+	 *
+	 * NOTE: Any new ELF note addition should be placed after this note.
+	 */
+	phdr = (struct elf_phdr *)bufp;
+	bufp += sizeof(struct elf_phdr);
+	phdr->p_type = PT_NOTE;
+	phdr->p_flags = 0;
+	phdr->p_vaddr = 0;
+	phdr->p_align = 0;
+
+	phdr->p_offset = 0;
+	phdr->p_paddr = 0;
+	phdr->p_filesz = 0;
+	phdr->p_memsz = 0;
+
+	(elf->e_phnum)++;
+
+	/* setup ELF PT_NOTE for vmcoreinfo */
+	phdr = (struct elf_phdr *)bufp;
+	bufp += sizeof(struct elf_phdr);
+	phdr->p_type	= PT_NOTE;
+	phdr->p_flags	= 0;
+	phdr->p_vaddr	= 0;
+	phdr->p_align	= 0;
+
+	phdr->p_paddr	= fadump_relocate(paddr_vmcoreinfo_note());
+	phdr->p_offset	= phdr->p_paddr;
+	phdr->p_memsz	= phdr->p_filesz = VMCOREINFO_NOTE_SIZE;
+
+	/* Increment number of program headers. */
+	(elf->e_phnum)++;
+
+	/* setup PT_LOAD sections. */
+	j = 0;
+	offset = 0;
+	raddr = fw_dump.boot_mem_addr[0];
+	for (i = 0; i < crash_mrange_info.mem_range_cnt; i++) {
+		u64 mbase, msize;
+
+		mbase = crash_mrange_info.mem_ranges[i].base;
+		msize = crash_mrange_info.mem_ranges[i].size;
+		if (!msize)
+			continue;
+
+		phdr = (struct elf_phdr *)bufp;
+		bufp += sizeof(struct elf_phdr);
+		phdr->p_type	= PT_LOAD;
+		phdr->p_flags	= PF_R|PF_W|PF_X;
+		phdr->p_offset	= mbase;
+
+		if (mbase == raddr) {
+			/*
+			 * The entire real memory region will be moved by
+			 * firmware to the specified destination_address.
+			 * Hence set the correct offset.
+			 */
+			phdr->p_offset = fw_dump.boot_mem_dest_addr + offset;
+			if (j < (fw_dump.boot_mem_regs_cnt - 1)) {
+				offset += fw_dump.boot_mem_sz[j];
+				raddr = fw_dump.boot_mem_addr[++j];
+			}
+		}
+
+		phdr->p_paddr = mbase;
+		phdr->p_vaddr = (unsigned long)__va(mbase);
+		phdr->p_filesz = msize;
+		phdr->p_memsz = msize;
+		phdr->p_align = 0;
+
+		/* Increment number of program headers. */
+		(elf->e_phnum)++;
+	}
+	return 0;
+}
+
+static unsigned long init_fadump_header(unsigned long addr)
+{
+	struct fadump_crash_info_header *fdh;
+
+	if (!addr)
+		return 0;
+
+	fdh = __va(addr);
+	addr += sizeof(struct fadump_crash_info_header);
+
+	memset(fdh, 0, sizeof(struct fadump_crash_info_header));
+	fdh->magic_number = FADUMP_CRASH_INFO_MAGIC;
+	fdh->elfcorehdr_addr = addr;
+	/* We will set the crashing cpu id in crash_fadump() during crash. */
+	fdh->crashing_cpu = FADUMP_CPU_UNKNOWN;
+
+	return addr;
+}
+
+static int register_fadump(void)
+{
+	unsigned long addr;
+	void *vaddr;
+	int ret;
+
+	/*
+	 * If no memory is reserved then we can not register for firmware-
+	 * assisted dump.
+	 */
+	if (!fw_dump.reserve_dump_area_size)
+		return -ENODEV;
+
+	ret = fadump_setup_crash_memory_ranges();
+	if (ret)
+		return ret;
+
+	addr = fw_dump.fadumphdr_addr;
+
+	/* Initialize fadump crash info header. */
+	addr = init_fadump_header(addr);
+	vaddr = __va(addr);
+
+	pr_debug("Creating ELF core headers at %#016lx\n", addr);
+	fadump_create_elfcore_headers(vaddr);
+
+	/* register the future kernel dump with firmware. */
+	pr_debug("Registering for firmware-assisted kernel dump...\n");
+	return fw_dump.ops->fadump_register(&fw_dump);
+}
+
+void fadump_cleanup(void)
+{
+	if (!fw_dump.fadump_supported)
+		return;
+
+	/* Invalidate the registration only if dump is active. */
+	if (fw_dump.dump_active) {
+		pr_debug("Invalidating firmware-assisted dump registration\n");
+		fw_dump.ops->fadump_invalidate(&fw_dump);
+	} else if (fw_dump.dump_registered) {
+		/* Un-register Firmware-assisted dump if it was registered. */
+		fw_dump.ops->fadump_unregister(&fw_dump);
+		fadump_free_mem_ranges(&crash_mrange_info);
+	}
+
+	if (fw_dump.ops->fadump_cleanup)
+		fw_dump.ops->fadump_cleanup(&fw_dump);
+}
+
+static void fadump_free_reserved_memory(unsigned long start_pfn,
+					unsigned long end_pfn)
+{
+	unsigned long pfn;
+	unsigned long time_limit = jiffies + HZ;
+
+	pr_info("freeing reserved memory (0x%llx - 0x%llx)\n",
+		PFN_PHYS(start_pfn), PFN_PHYS(end_pfn));
+
+	for (pfn = start_pfn; pfn < end_pfn; pfn++) {
+		free_reserved_page(pfn_to_page(pfn));
+
+		if (time_after(jiffies, time_limit)) {
+			cond_resched();
+			time_limit = jiffies + HZ;
+		}
+	}
+}
+
+/*
+ * Skip memory holes and free memory that was actually reserved.
+ */
+static void fadump_release_reserved_area(u64 start, u64 end)
+{
+	unsigned long reg_spfn, reg_epfn;
+	u64 tstart, tend, spfn, epfn;
+	int i;
+
+	spfn = PHYS_PFN(start);
+	epfn = PHYS_PFN(end);
+
+	for_each_mem_pfn_range(i, MAX_NUMNODES, &reg_spfn, &reg_epfn, NULL) {
+		tstart = max_t(u64, spfn, reg_spfn);
+		tend   = min_t(u64, epfn, reg_epfn);
+
+		if (tstart < tend) {
+			fadump_free_reserved_memory(tstart, tend);
+
+			if (tend == epfn)
+				break;
+
+			spfn = tend;
+		}
+	}
+}
+
+/*
+ * Sort the mem ranges in-place and merge adjacent ranges
+ * to minimize the memory ranges count.
+ */
+static void sort_and_merge_mem_ranges(struct fadump_mrange_info *mrange_info)
+{
+	struct fadump_memory_range *mem_ranges;
+	struct fadump_memory_range tmp_range;
+	u64 base, size;
+	int i, j, idx;
+
+	if (!reserved_mrange_info.mem_range_cnt)
+		return;
+
+	/* Sort the memory ranges */
+	mem_ranges = mrange_info->mem_ranges;
+	for (i = 0; i < mrange_info->mem_range_cnt; i++) {
+		idx = i;
+		for (j = (i + 1); j < mrange_info->mem_range_cnt; j++) {
+			if (mem_ranges[idx].base > mem_ranges[j].base)
+				idx = j;
+		}
+		if (idx != i) {
+			tmp_range = mem_ranges[idx];
+			mem_ranges[idx] = mem_ranges[i];
+			mem_ranges[i] = tmp_range;
+		}
+	}
+
+	/* Merge adjacent reserved ranges */
+	idx = 0;
+	for (i = 1; i < mrange_info->mem_range_cnt; i++) {
+		base = mem_ranges[i-1].base;
+		size = mem_ranges[i-1].size;
+		if (mem_ranges[i].base == (base + size))
+			mem_ranges[idx].size += mem_ranges[i].size;
+		else {
+			idx++;
+			if (i == idx)
+				continue;
+
+			mem_ranges[idx] = mem_ranges[i];
+		}
+	}
+	mrange_info->mem_range_cnt = idx + 1;
+}
+
+/*
+ * Scan reserved-ranges to consider them while reserving/releasing
+ * memory for FADump.
+ */
+static void __init early_init_dt_scan_reserved_ranges(unsigned long node)
+{
+	const __be32 *prop;
+	int len, ret = -1;
+	unsigned long i;
+
+	/* reserved-ranges already scanned */
+	if (reserved_mrange_info.mem_range_cnt != 0)
+		return;
+
+	prop = of_get_flat_dt_prop(node, "reserved-ranges", &len);
+	if (!prop)
+		return;
+
+	/*
+	 * Each reserved range is an (address,size) pair, 2 cells each,
+	 * totalling 4 cells per range.
+	 */
+	for (i = 0; i < len / (sizeof(*prop) * 4); i++) {
+		u64 base, size;
+
+		base = of_read_number(prop + (i * 4) + 0, 2);
+		size = of_read_number(prop + (i * 4) + 2, 2);
+
+		if (size) {
+			ret = fadump_add_mem_range(&reserved_mrange_info,
+						   base, base + size);
+			if (ret < 0) {
+				pr_warn("some reserved ranges are ignored!\n");
+				break;
+			}
+		}
+	}
+
+	/* Compact reserved ranges */
+	sort_and_merge_mem_ranges(&reserved_mrange_info);
+}
+
+/*
+ * Release the memory that was reserved during early boot to preserve the
+ * crash'ed kernel's memory contents except reserved dump area (permanent
+ * reservation) and reserved ranges used by F/W. The released memory will
+ * be available for general use.
+ */
+static void fadump_release_memory(u64 begin, u64 end)
+{
+	u64 ra_start, ra_end, tstart;
+	int i, ret;
+
+	ra_start = fw_dump.reserve_dump_area_start;
+	ra_end = ra_start + fw_dump.reserve_dump_area_size;
+
+	/*
+	 * If reserved ranges array limit is hit, overwrite the last reserved
+	 * memory range with reserved dump area to ensure it is excluded from
+	 * the memory being released (reused for next FADump registration).
+	 */
+	if (reserved_mrange_info.mem_range_cnt ==
+	    reserved_mrange_info.max_mem_ranges)
+		reserved_mrange_info.mem_range_cnt--;
+
+	ret = fadump_add_mem_range(&reserved_mrange_info, ra_start, ra_end);
+	if (ret != 0)
+		return;
+
+	/* Get the reserved ranges list in order first. */
+	sort_and_merge_mem_ranges(&reserved_mrange_info);
+
+	/* Exclude reserved ranges and release remaining memory */
+	tstart = begin;
+	for (i = 0; i < reserved_mrange_info.mem_range_cnt; i++) {
+		ra_start = reserved_mrange_info.mem_ranges[i].base;
+		ra_end = ra_start + reserved_mrange_info.mem_ranges[i].size;
+
+		if (tstart >= ra_end)
+			continue;
+
+		if (tstart < ra_start)
+			fadump_release_reserved_area(tstart, ra_start);
+		tstart = ra_end;
+	}
+
+	if (tstart < end)
+		fadump_release_reserved_area(tstart, end);
+}
+
+static void fadump_invalidate_release_mem(void)
+{
+	mutex_lock(&fadump_mutex);
+	if (!fw_dump.dump_active) {
+		mutex_unlock(&fadump_mutex);
+		return;
+	}
+
+	fadump_cleanup();
+	mutex_unlock(&fadump_mutex);
+
+	fadump_release_memory(fw_dump.boot_mem_top, memblock_end_of_DRAM());
+	fadump_free_cpu_notes_buf();
+
+	/*
+	 * Setup kernel metadata and initialize the kernel dump
+	 * memory structure for FADump re-registration.
+	 */
+	if (fw_dump.ops->fadump_setup_metadata &&
+	    (fw_dump.ops->fadump_setup_metadata(&fw_dump) < 0))
+		pr_warn("Failed to setup kernel metadata!\n");
+	fw_dump.ops->fadump_init_mem_struct(&fw_dump);
+}
+
+static ssize_t release_mem_store(struct kobject *kobj,
+				 struct kobj_attribute *attr,
+				 const char *buf, size_t count)
+{
+	int input = -1;
+
+	if (!fw_dump.dump_active)
+		return -EPERM;
+
+	if (kstrtoint(buf, 0, &input))
+		return -EINVAL;
+
+	if (input == 1) {
+		/*
+		 * Take away the '/proc/vmcore'. We are releasing the dump
+		 * memory, hence it will not be valid anymore.
+		 */
+#ifdef CONFIG_PROC_VMCORE
+		vmcore_cleanup();
+#endif
+		fadump_invalidate_release_mem();
+
+	} else
+		return -EINVAL;
+	return count;
+}
+
+/* Release the reserved memory and disable the FADump */
+static void unregister_fadump(void)
+{
+	fadump_cleanup();
+	fadump_release_memory(fw_dump.reserve_dump_area_start,
+			      fw_dump.reserve_dump_area_size);
+	fw_dump.fadump_enabled = 0;
+	kobject_put(fadump_kobj);
+}
+
+static ssize_t enabled_show(struct kobject *kobj,
+			    struct kobj_attribute *attr,
+			    char *buf)
+{
+	return sprintf(buf, "%d\n", fw_dump.fadump_enabled);
+}
+
+static ssize_t mem_reserved_show(struct kobject *kobj,
+				 struct kobj_attribute *attr,
+				 char *buf)
+{
+	return sprintf(buf, "%ld\n", fw_dump.reserve_dump_area_size);
+}
+
+static ssize_t registered_show(struct kobject *kobj,
+			       struct kobj_attribute *attr,
+			       char *buf)
+{
+	return sprintf(buf, "%d\n", fw_dump.dump_registered);
+}
+
+static ssize_t registered_store(struct kobject *kobj,
+				struct kobj_attribute *attr,
+				const char *buf, size_t count)
+{
+	int ret = 0;
+	int input = -1;
+
+	if (!fw_dump.fadump_enabled || fw_dump.dump_active)
+		return -EPERM;
+
+	if (kstrtoint(buf, 0, &input))
+		return -EINVAL;
+
+	mutex_lock(&fadump_mutex);
+
+	switch (input) {
+	case 0:
+		if (fw_dump.dump_registered == 0) {
+			goto unlock_out;
+		}
+
+		/* Un-register Firmware-assisted dump */
+		pr_debug("Un-register firmware-assisted dump\n");
+		fw_dump.ops->fadump_unregister(&fw_dump);
+		break;
+	case 1:
+		if (fw_dump.dump_registered == 1) {
+			/* Un-register Firmware-assisted dump */
+			fw_dump.ops->fadump_unregister(&fw_dump);
+		}
+		/* Register Firmware-assisted dump */
+		ret = register_fadump();
+		break;
+	default:
+		ret = -EINVAL;
+		break;
+	}
+
+unlock_out:
+	mutex_unlock(&fadump_mutex);
+	return ret < 0 ? ret : count;
+}
+
+static int fadump_region_show(struct seq_file *m, void *private)
+{
+	if (!fw_dump.fadump_enabled)
+		return 0;
+
+	mutex_lock(&fadump_mutex);
+	fw_dump.ops->fadump_region_show(&fw_dump, m);
+	mutex_unlock(&fadump_mutex);
+	return 0;
+}
+
+static struct kobj_attribute release_attr = __ATTR_WO(release_mem);
+static struct kobj_attribute enable_attr = __ATTR_RO(enabled);
+static struct kobj_attribute register_attr = __ATTR_RW(registered);
+static struct kobj_attribute mem_reserved_attr = __ATTR_RO(mem_reserved);
+
+static struct attribute *fadump_attrs[] = {
+	&enable_attr.attr,
+	&register_attr.attr,
+	&mem_reserved_attr.attr,
+	NULL,
+};
+
+ATTRIBUTE_GROUPS(fadump);
+
+DEFINE_SHOW_ATTRIBUTE(fadump_region);
+
+static void fadump_init_files(void)
+{
+	int rc = 0;
+
+	fadump_kobj = kobject_create_and_add("fadump", kernel_kobj);
+	if (!fadump_kobj) {
+		pr_err("failed to create fadump kobject\n");
+		return;
+	}
+
+	debugfs_create_file("fadump_region", 0444, powerpc_debugfs_root, NULL,
+			    &fadump_region_fops);
+
+	if (fw_dump.dump_active) {
+		rc = sysfs_create_file(fadump_kobj, &release_attr.attr);
+		if (rc)
+			pr_err("unable to create release_mem sysfs file (%d)\n",
+			       rc);
+	}
+
+	rc = sysfs_create_groups(fadump_kobj, fadump_groups);
+	if (rc) {
+		pr_err("sysfs group creation failed (%d), unregistering FADump",
+		       rc);
+		unregister_fadump();
+		return;
+	}
+
+	/*
+	 * The FADump sysfs are moved from kernel_kobj to fadump_kobj need to
+	 * create symlink at old location to maintain backward compatibility.
+	 *
+	 *      - fadump_enabled -> fadump/enabled
+	 *      - fadump_registered -> fadump/registered
+	 *      - fadump_release_mem -> fadump/release_mem
+	 */
+	rc = compat_only_sysfs_link_entry_to_kobj(kernel_kobj, fadump_kobj,
+						  "enabled", "fadump_enabled");
+	if (rc) {
+		pr_err("unable to create fadump_enabled symlink (%d)", rc);
+		return;
+	}
+
+	rc = compat_only_sysfs_link_entry_to_kobj(kernel_kobj, fadump_kobj,
+						  "registered",
+						  "fadump_registered");
+	if (rc) {
+		pr_err("unable to create fadump_registered symlink (%d)", rc);
+		sysfs_remove_link(kernel_kobj, "fadump_enabled");
+		return;
+	}
+
+	if (fw_dump.dump_active) {
+		rc = compat_only_sysfs_link_entry_to_kobj(kernel_kobj,
+							  fadump_kobj,
+							  "release_mem",
+							  "fadump_release_mem");
+		if (rc)
+			pr_err("unable to create fadump_release_mem symlink (%d)",
+			       rc);
+	}
+	return;
+}
+
+/*
+ * Prepare for firmware-assisted dump.
+ */
+int __init setup_fadump(void)
+{
+	if (!fw_dump.fadump_supported)
+		return 0;
+
+	fadump_init_files();
+	fadump_show_config();
+
+	if (!fw_dump.fadump_enabled)
+		return 1;
+
+	/*
+	 * If dump data is available then see if it is valid and prepare for
+	 * saving it to the disk.
+	 */
+	if (fw_dump.dump_active) {
+		/*
+		 * if dump process fails then invalidate the registration
+		 * and release memory before proceeding for re-registration.
+		 */
+		if (fw_dump.ops->fadump_process(&fw_dump) < 0)
+			fadump_invalidate_release_mem();
+	}
+	/* Initialize the kernel dump memory structure for FAD registration. */
+	else if (fw_dump.reserve_dump_area_size)
+		fw_dump.ops->fadump_init_mem_struct(&fw_dump);
+
+	/*
+	 * In case of panic, fadump is triggered via ppc_panic_event()
+	 * panic notifier. Setting crash_kexec_post_notifiers to 'true'
+	 * lets panic() function take crash friendly path before panic
+	 * notifiers are invoked.
+	 */
+	crash_kexec_post_notifiers = true;
+
+	return 1;
+}
+subsys_initcall(setup_fadump);
+#else /* !CONFIG_PRESERVE_FA_DUMP */
+
+/* Scan the Firmware Assisted dump configuration details. */
+int __init early_init_dt_scan_fw_dump(unsigned long node, const char *uname,
+				      int depth, void *data)
+{
+	if ((depth != 1) || (strcmp(uname, "ibm,opal") != 0))
+		return 0;
+
+	opal_fadump_dt_scan(&fw_dump, node);
+	return 1;
+}
+
+/*
+ * When dump is active but PRESERVE_FA_DUMP is enabled on the kernel,
+ * preserve crash data. The subsequent memory preserving kernel boot
+ * is likely to process this crash data.
+ */
+int __init fadump_reserve_mem(void)
+{
+	if (fw_dump.dump_active) {
+		/*
+		 * If last boot has crashed then reserve all the memory
+		 * above boot memory to preserve crash data.
+		 */
+		pr_info("Preserving crash data for processing in next boot.\n");
+		fadump_reserve_crash_area(fw_dump.boot_mem_top);
+	} else
+		pr_debug("FADump-aware kernel..\n");
+
+	return 1;
+}
+#endif /* CONFIG_PRESERVE_FA_DUMP */
+
+/* Preserve everything above the base address */
+static void __init fadump_reserve_crash_area(u64 base)
+{
+	u64 i, mstart, mend, msize;
+
+	for_each_mem_range(i, &mstart, &mend) {
+		msize  = mend - mstart;
+
+		if ((mstart + msize) < base)
+			continue;
+
+		if (mstart < base) {
+			msize -= (base - mstart);
+			mstart = base;
+		}
+
+		pr_info("Reserving %lluMB of memory at %#016llx for preserving crash data",
+			(msize >> 20), mstart);
+		memblock_reserve(mstart, msize);
+	}
+}
+
+unsigned long __init arch_reserved_kernel_pages(void)
+{
+	return memblock_reserved_size() / PAGE_SIZE;
+}