/*
 * 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
 *
 * This program is free software; you can redistribute it and/or modify
 * it under the terms of the GNU General Public License as published by
 * the Free Software Foundation; either version 2 of the License, or
 * (at your option) any later version.
 *
 * This program is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 * GNU General Public License for more details.
 *
 * You should have received a copy of the GNU General Public License
 * along with this program; if not, write to the Free Software
 * Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA.
 *
 * 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/debugfs.h>
#include <linux/seq_file.h>
#include <linux/crash_dump.h>
#include <linux/kobject.h>
#include <linux/sysfs.h>

#include <asm/page.h>
#include <asm/prom.h>
#include <asm/rtas.h>
#include <asm/fadump.h>
#include <asm/debug.h>
#include <asm/setup.h>

static struct fw_dump fw_dump;
static struct fadump_mem_struct fdm;
static const struct fadump_mem_struct *fdm_active;

static DEFINE_MUTEX(fadump_mutex);
struct fad_crash_memory_ranges crash_memory_ranges[INIT_CRASHMEM_RANGES];
int crash_mem_ranges;

/* 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)
{
        const __be32 *sections;
        int i, num_sections;
        int size;
        const __be32 *token;

        if (depth != 1 || strcmp(uname, "rtas") != 0)
                return 0;

        /*
         * Check if Firmware Assisted dump is supported. if yes, check
         * if dump has been initiated on last reboot.
         */
        token = of_get_flat_dt_prop(node, "ibm,configure-kernel-dump", NULL);
        if (!token)
                return 1;

        fw_dump.fadump_supported = 1;
        fw_dump.ibm_configure_kernel_dump = be32_to_cpu(*token);

        /*
         * The 'ibm,kernel-dump' rtas node is present only if there is
         * dump data waiting for us.
         */
        fdm_active = of_get_flat_dt_prop(node, "ibm,kernel-dump", NULL);
        if (fdm_active)
                fw_dump.dump_active = 1;

        /* Get the sizes required to store dump data for the firmware provided
         * dump sections.
         * For each dump section type supported, a 32bit cell which defines
         * the ID of a supported section followed by two 32 bit cells which
         * gives teh size of the section in bytes.
         */
        sections = of_get_flat_dt_prop(node, "ibm,configure-kernel-dump-sizes",
                                        &size);

        if (!sections)
                return 1;

        num_sections = size / (3 * sizeof(u32));

        for (i = 0; i < num_sections; i++, sections += 3) {
                u32 type = (u32)of_read_number(sections, 1);

                switch (type) {
                case FADUMP_CPU_STATE_DATA:
                        fw_dump.cpu_state_data_size =
                                        of_read_ulong(&sections[1], 2);
                        break;
                case FADUMP_HPTE_REGION:
                        fw_dump.hpte_region_size =
                                        of_read_ulong(&sections[1], 2);
                        break;
                }
        }

        return 1;
}

int is_fadump_active(void)
{
        return fw_dump.dump_active;
}

/* Print firmware assisted dump configurations for debugging purpose. */
static void fadump_show_config(void)
{
        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);
}

static unsigned long init_fadump_mem_struct(struct fadump_mem_struct *fdm,
                                unsigned long addr)
{
        if (!fdm)
                return 0;

        memset(fdm, 0, sizeof(struct fadump_mem_struct));
        addr = addr & PAGE_MASK;

        fdm->header.dump_format_version = cpu_to_be32(0x00000001);
        fdm->header.dump_num_sections = cpu_to_be16(3);
        fdm->header.dump_status_flag = 0;
        fdm->header.offset_first_dump_section =
                cpu_to_be32((u32)offsetof(struct fadump_mem_struct, cpu_state_data));

        /*
         * Fields for disk dump option.
         * We are not using disk dump option, hence set these fields to 0.
         */
        fdm->header.dd_block_size = 0;
        fdm->header.dd_block_offset = 0;
        fdm->header.dd_num_blocks = 0;
        fdm->header.dd_offset_disk_path = 0;

        /* set 0 to disable an automatic dump-reboot. */
        fdm->header.max_time_auto = 0;

        /* Kernel dump sections */
        /* cpu state data section. */
        fdm->cpu_state_data.request_flag = cpu_to_be32(FADUMP_REQUEST_FLAG);
        fdm->cpu_state_data.source_data_type = cpu_to_be16(FADUMP_CPU_STATE_DATA);
        fdm->cpu_state_data.source_address = 0;
        fdm->cpu_state_data.source_len = cpu_to_be64(fw_dump.cpu_state_data_size);
        fdm->cpu_state_data.destination_address = cpu_to_be64(addr);
        addr += fw_dump.cpu_state_data_size;

        /* hpte region section */
        fdm->hpte_region.request_flag = cpu_to_be32(FADUMP_REQUEST_FLAG);
        fdm->hpte_region.source_data_type = cpu_to_be16(FADUMP_HPTE_REGION);
        fdm->hpte_region.source_address = 0;
        fdm->hpte_region.source_len = cpu_to_be64(fw_dump.hpte_region_size);
        fdm->hpte_region.destination_address = cpu_to_be64(addr);
        addr += fw_dump.hpte_region_size;

        /* RMA region section */
        fdm->rmr_region.request_flag = cpu_to_be32(FADUMP_REQUEST_FLAG);
        fdm->rmr_region.source_data_type = cpu_to_be16(FADUMP_REAL_MODE_REGION);
        fdm->rmr_region.source_address = cpu_to_be64(RMA_START);
        fdm->rmr_region.source_len = cpu_to_be64(fw_dump.boot_memory_size);
        fdm->rmr_region.destination_address = cpu_to_be64(addr);
        addr += fw_dump.boot_memory_size;

        return addr;
}

/**
 * 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 inline unsigned long fadump_calculate_reserve_size(void)
{
        unsigned long size;

        /*
         * Check if the size is specified through fadump_reserve_mem= cmdline
         * option. If yes, then use that.
         */
        if (fw_dump.reserve_bootvar)
                return fw_dump.reserve_bootvar;

        /* divide by 20 to get 5% of value */
        size = memblock_end_of_DRAM() / 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;

        return (size > MIN_BOOT_MEM ? size : MIN_BOOT_MEM);
}

/*
 * 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);
        return size;
}

int __init fadump_reserve_mem(void)
{
        unsigned long base, size, memory_boundary;

        if (!fw_dump.fadump_enabled)
                return 0;

        if (!fw_dump.fadump_supported) {
                printk(KERN_INFO "Firmware-assisted dump is not supported on"
                                " this hardware\n");
                fw_dump.fadump_enabled = 0;
                return 0;
        }
        /*
         * Initialize boot memory size
         * If dump is active then we have already calculated the size during
         * first kernel.
         */
        if (fdm_active)
                fw_dump.boot_memory_size = be64_to_cpu(fdm_active->rmr_region.source_len);
        else
                fw_dump.boot_memory_size = fadump_calculate_reserve_size();

        /*
         * 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)
                memory_boundary = memory_limit;
        else
                memory_boundary = memblock_end_of_DRAM();

        if (fw_dump.dump_active) {
                printk(KERN_INFO "Firmware-assisted dump is active.\n");
                /*
                 * 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
                 * will be released for general use once the dump is saved.
                 */
                base = fw_dump.boot_memory_size;
                size = memory_boundary - base;
                memblock_reserve(base, size);
                printk(KERN_INFO "Reserved %ldMB of memory at %ldMB "
                                "for saving crash dump\n",
                                (unsigned long)(size >> 20),
                                (unsigned long)(base >> 20));

                fw_dump.fadumphdr_addr =
                                be64_to_cpu(fdm_active->rmr_region.destination_address) +
                                be64_to_cpu(fdm_active->rmr_region.source_len);
                pr_debug("fadumphdr_addr = %p\n",
                                (void *) fw_dump.fadumphdr_addr);
        } else {
                /* Reserve the memory at the top of memory. */
                size = get_fadump_area_size();
                base = memory_boundary - size;
                memblock_reserve(base, size);
                printk(KERN_INFO "Reserved %ldMB of memory at %ldMB "
                                "for firmware-assisted dump\n",
                                (unsigned long)(size >> 20),
                                (unsigned long)(base >> 20));
        }
        fw_dump.reserve_dump_area_start = base;
        fw_dump.reserve_dump_area_size = size;
        return 1;
}

/* 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;

        return 0;
}
early_param("fadump", early_fadump_param);

/* Look for fadump_reserve_mem= cmdline option */
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);

static void register_fw_dump(struct fadump_mem_struct *fdm)
{
        int rc;
        unsigned int wait_time;

        pr_debug("Registering for firmware-assisted kernel dump...\n");

        /* TODO: Add upper time limit for the delay */
        do {
                rc = rtas_call(fw_dump.ibm_configure_kernel_dump, 3, 1, NULL,
                        FADUMP_REGISTER, fdm,
                        sizeof(struct fadump_mem_struct));

                wait_time = rtas_busy_delay_time(rc);
                if (wait_time)
                        mdelay(wait_time);

        } while (wait_time);

        switch (rc) {
        case -1:
                printk(KERN_ERR "Failed to register firmware-assisted kernel"
                        " dump. Hardware Error(%d).\n", rc);
                break;
        case -3:
                printk(KERN_ERR "Failed to register firmware-assisted kernel"
                        " dump. Parameter Error(%d).\n", rc);
                break;
        case -9:
                printk(KERN_ERR "firmware-assisted kernel dump is already "
                        " registered.");
                fw_dump.dump_registered = 1;
                break;
        case 0:
                printk(KERN_INFO "firmware-assisted kernel dump registration"
                        " is successful\n");
                fw_dump.dump_registered = 1;
                break;
        }
}

void crash_fadump(struct pt_regs *regs, const char *str)
{
        struct fadump_crash_info_header *fdh = NULL;

        if (!fw_dump.dump_registered || !fw_dump.fadumphdr_addr)
                return;

        fdh = __va(fw_dump.fadumphdr_addr);
        crashing_cpu = smp_processor_id();
        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;

        /* Call ibm,os-term rtas call to trigger firmware assisted dump */
        rtas_os_term((char *)str);
}

#define GPR_MASK        0xffffff0000000000
static inline int fadump_gpr_index(u64 id)
{
        int i = -1;
        char str[3];

        if ((id & GPR_MASK) == REG_ID("GPR")) {
                /* get the digits at the end */
                id &= ~GPR_MASK;
                id >>= 24;
                str[2] = '\0';
                str[1] = id & 0xff;
                str[0] = (id >> 8) & 0xff;
                sscanf(str, "%d", &i);
                if (i > 31)
                        i = -1;
        }
        return i;
}

static inline void fadump_set_regval(struct pt_regs *regs, u64 reg_id,
                                                                u64 reg_val)
{
        int i;

        i = fadump_gpr_index(reg_id);
        if (i >= 0)
                regs->gpr[i] = (unsigned long)reg_val;
        else if (reg_id == REG_ID("NIA"))
                regs->nip = (unsigned long)reg_val;
        else if (reg_id == REG_ID("MSR"))
                regs->msr = (unsigned long)reg_val;
        else if (reg_id == REG_ID("CTR"))
                regs->ctr = (unsigned long)reg_val;
        else if (reg_id == REG_ID("LR"))
                regs->link = (unsigned long)reg_val;
        else if (reg_id == REG_ID("XER"))
                regs->xer = (unsigned long)reg_val;
        else if (reg_id == REG_ID("CR"))
                regs->ccr = (unsigned long)reg_val;
        else if (reg_id == REG_ID("DAR"))
                regs->dar = (unsigned long)reg_val;
        else if (reg_id == REG_ID("DSISR"))
                regs->dsisr = (unsigned long)reg_val;
}

static struct fadump_reg_entry*
fadump_read_registers(struct fadump_reg_entry *reg_entry, struct pt_regs *regs)
{
        memset(regs, 0, sizeof(struct pt_regs));

        while (be64_to_cpu(reg_entry->reg_id) != REG_ID("CPUEND")) {
                fadump_set_regval(regs, be64_to_cpu(reg_entry->reg_id),
                                        be64_to_cpu(reg_entry->reg_value));
                reg_entry++;
        }
        reg_entry++;
        return reg_entry;
}

static u32 *fadump_append_elf_note(u32 *buf, char *name, unsigned type,
                                                void *data, size_t data_len)
{
        struct elf_note note;

        note.n_namesz = strlen(name) + 1;
        note.n_descsz = data_len;
        note.n_type   = type;
        memcpy(buf, &note, sizeof(note));
        buf += (sizeof(note) + 3)/4;
        memcpy(buf, name, note.n_namesz);
        buf += (note.n_namesz + 3)/4;
        memcpy(buf, data, note.n_descsz);
        buf += (note.n_descsz + 3)/4;

        return buf;
}

static void fadump_final_note(u32 *buf)
{
        struct elf_note note;

        note.n_namesz = 0;
        note.n_descsz = 0;
        note.n_type   = 0;
        memcpy(buf, &note, sizeof(note));
}

static 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 = fadump_append_elf_note(buf, KEXEC_CORE_NOTE_NAME, NT_PRSTATUS,
                                &prstatus, sizeof(prstatus));
        return buf;
}

static void fadump_update_elfcore_header(char *bufp)
{
        struct elfhdr *elf;
        struct elf_phdr *phdr;

        elf = (struct elfhdr *)bufp;
        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 = fw_dump.cpu_notes_buf;
                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_cpu_notes_buf_alloc(unsigned long size)
{
        void *vaddr;
        struct page *page;
        unsigned long order, count, i;

        order = get_order(size);
        vaddr = (void *)__get_free_pages(GFP_KERNEL|__GFP_ZERO, order);
        if (!vaddr)
                return NULL;

        count = 1 << order;
        page = virt_to_page(vaddr);
        for (i = 0; i < count; i++)
                SetPageReserved(page + i);
        return vaddr;
}

static void fadump_cpu_notes_buf_free(unsigned long vaddr, unsigned long size)
{
        struct page *page;
        unsigned long order, count, i;

        order = get_order(size);
        count = 1 << order;
        page = virt_to_page(vaddr);
        for (i = 0; i < count; i++)
                ClearPageReserved(page + i);
        __free_pages(page, order);
}

/*
 * Read CPU state dump data and convert it into ELF notes.
 * The CPU dump starts with magic number "REGSAVE". NumCpusOffset should be
 * used to access the data to allow for additional fields to be added without
 * affecting compatibility. Each list of registers for a CPU starts with
 * "CPUSTRT" and ends with "CPUEND". Each register entry is of 16 bytes,
 * 8 Byte ASCII identifier and 8 Byte register value. The register entry
 * with identifier "CPUSTRT" and "CPUEND" contains 4 byte cpu id as part
 * of register value. For more details refer to PAPR document.
 *
 * Only for the crashing cpu we ignore the CPU dump data and get exact
 * state from fadump crash info structure populated by first kernel at the
 * time of crash.
 */
static int __init fadump_build_cpu_notes(const struct fadump_mem_struct *fdm)
{
        struct fadump_reg_save_area_header *reg_header;
        struct fadump_reg_entry *reg_entry;
        struct fadump_crash_info_header *fdh = NULL;
        void *vaddr;
        unsigned long addr;
        u32 num_cpus, *note_buf;
        struct pt_regs regs;
        int i, rc = 0, cpu = 0;

        if (!fdm->cpu_state_data.bytes_dumped)
                return -EINVAL;

        addr = be64_to_cpu(fdm->cpu_state_data.destination_address);
        vaddr = __va(addr);

        reg_header = vaddr;
        if (be64_to_cpu(reg_header->magic_number) != REGSAVE_AREA_MAGIC) {
                printk(KERN_ERR "Unable to read register save area.\n");
                return -ENOENT;
        }
        pr_debug("--------CPU State Data------------\n");
        pr_debug("Magic Number: %llx\n", be64_to_cpu(reg_header->magic_number));
        pr_debug("NumCpuOffset: %x\n", be32_to_cpu(reg_header->num_cpu_offset));

        vaddr += be32_to_cpu(reg_header->num_cpu_offset);
        num_cpus = be32_to_cpu(*((__be32 *)(vaddr)));
        pr_debug("NumCpus     : %u\n", num_cpus);
        vaddr += sizeof(u32);
        reg_entry = (struct fadump_reg_entry *)vaddr;

        /* 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);
        note_buf = fadump_cpu_notes_buf_alloc(fw_dump.cpu_notes_buf_size);
        if (!note_buf) {
                printk(KERN_ERR "Failed to allocate 0x%lx bytes for "
                        "cpu notes buffer\n", fw_dump.cpu_notes_buf_size);
                return -ENOMEM;
        }
        fw_dump.cpu_notes_buf = __pa(note_buf);

        pr_debug("Allocated buffer for cpu notes of size %ld at %p\n",
                        (num_cpus * sizeof(note_buf_t)), note_buf);

        if (fw_dump.fadumphdr_addr)
                fdh = __va(fw_dump.fadumphdr_addr);

        for (i = 0; i < num_cpus; i++) {
                if (be64_to_cpu(reg_entry->reg_id) != REG_ID("CPUSTRT")) {
                        printk(KERN_ERR "Unable to read CPU state data\n");
                        rc = -ENOENT;
                        goto error_out;
                }
                /* Lower 4 bytes of reg_value contains logical cpu id */
                cpu = be64_to_cpu(reg_entry->reg_value) & FADUMP_CPU_ID_MASK;
                if (fdh && !cpumask_test_cpu(cpu, &fdh->online_mask)) {
                        SKIP_TO_NEXT_CPU(reg_entry);
                        continue;
                }
                pr_debug("Reading register data for cpu %d...\n", cpu);
                if (fdh && fdh->crashing_cpu == cpu) {
                        regs = fdh->regs;
                        note_buf = fadump_regs_to_elf_notes(note_buf, &regs);
                        SKIP_TO_NEXT_CPU(reg_entry);
                } else {
                        reg_entry++;
                        reg_entry = fadump_read_registers(reg_entry, &regs);
                        note_buf = fadump_regs_to_elf_notes(note_buf, &regs);
                }
        }
        fadump_final_note(note_buf);

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

error_out:
        fadump_cpu_notes_buf_free((unsigned long)__va(fw_dump.cpu_notes_buf),
                                        fw_dump.cpu_notes_buf_size);
        fw_dump.cpu_notes_buf = 0;
        fw_dump.cpu_notes_buf_size = 0;
        return rc;

}

/*
 * Validate and process the dump data stored by firmware before exporting
 * it through '/proc/vmcore'.
 */
static int __init process_fadump(const struct fadump_mem_struct *fdm_active)
{
        struct fadump_crash_info_header *fdh;
        int rc = 0;

        if (!fdm_active || !fw_dump.fadumphdr_addr)
                return -EINVAL;

        /* Check if the dump data is valid. */
        if ((be16_to_cpu(fdm_active->header.dump_status_flag) == FADUMP_ERROR_FLAG) ||
                        (fdm_active->cpu_state_data.error_flags != 0) ||
                        (fdm_active->rmr_region.error_flags != 0)) {
                printk(KERN_ERR "Dump taken by platform is not valid\n");
                return -EINVAL;
        }
        if ((fdm_active->rmr_region.bytes_dumped !=
                        fdm_active->rmr_region.source_len) ||
                        !fdm_active->cpu_state_data.bytes_dumped) {
                printk(KERN_ERR "Dump taken by platform is incomplete\n");
                return -EINVAL;
        }

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

        rc = fadump_build_cpu_notes(fdm_active);
        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 0;
}

static inline void fadump_add_crash_memory(unsigned long long base,
                                        unsigned long long end)
{
        if (base == end)
                return;

        pr_debug("crash_memory_range[%d] [%#016llx-%#016llx], %#llx bytes\n",
                crash_mem_ranges, base, end - 1, (end - base));
        crash_memory_ranges[crash_mem_ranges].base = base;
        crash_memory_ranges[crash_mem_ranges].size = end - base;
        crash_mem_ranges++;
}

static void fadump_exclude_reserved_area(unsigned long long start,
                                        unsigned long long end)
{
        unsigned long long ra_start, ra_end;

        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)) {
                        fadump_add_crash_memory(start, ra_start);
                        fadump_add_crash_memory(ra_end, end);
                } else if (start < ra_start) {
                        fadump_add_crash_memory(start, ra_start);
                } else if (ra_end < end) {
                        fadump_add_crash_memory(ra_end, end);
                }
        } else
                fadump_add_crash_memory(start, end);
}

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;
        elf->e_flags = ELF_CORE_EFLAGS;
        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 void fadump_setup_crash_memory_ranges(void)
{
        struct memblock_region *reg;
        unsigned long long start, end;

        pr_debug("Setup crash memory ranges.\n");
        crash_mem_ranges = 0;
        /*
         * add the first memory chunk (RMA_START through boot_memory_size) as
         * a separate memory chunk. The reason is, at the time crash firmware
         * will move the content of this memory chunk to different location
         * specified during fadump registration. We need to create a separate
         * program header for this chunk with the correct offset.
         */
        fadump_add_crash_memory(RMA_START, fw_dump.boot_memory_size);

        for_each_memblock(memory, reg) {
                start = (unsigned long long)reg->base;
                end = start + (unsigned long long)reg->size;
                if (start == RMA_START && end >= fw_dump.boot_memory_size)
                        start = fw_dump.boot_memory_size;

                /* add this range excluding the reserved dump area. */
                fadump_exclude_reserved_area(start, end);
        }
}

/*
 * 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)
{
        if (paddr > RMA_START && paddr < fw_dump.boot_memory_size)
                return be64_to_cpu(fdm.rmr_region.destination_address) + paddr;
        else
                return paddr;
}

static int fadump_create_elfcore_headers(char *bufp)
{
        struct elfhdr *elf;
        struct elf_phdr *phdr;
        int i;

        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   = vmcoreinfo_max_size;
        phdr->p_filesz  = vmcoreinfo_max_size;

        /* Increment number of program headers. */
        (elf->e_phnum)++;

        /* setup PT_LOAD sections. */

        for (i = 0; i < crash_mem_ranges; i++) {
                unsigned long long mbase, msize;
                mbase = crash_memory_ranges[i].base;
                msize = crash_memory_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 == RMA_START) {
                        /*
                         * The entire RMA region will be moved by firmware
                         * to the specified destination_address. Hence set
                         * the correct offset.
                         */
                        phdr->p_offset = be64_to_cpu(fdm.rmr_region.destination_address);
                }

                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;

        fw_dump.fadumphdr_addr = addr;
        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 = CPU_UNKNOWN;

        return addr;
}

static void register_fadump(void)
{
        unsigned long addr;
        void *vaddr;

        /*
         * If no memory is reserved then we can not register for firmware-
         * assisted dump.
         */
        if (!fw_dump.reserve_dump_area_size)
                return;

        fadump_setup_crash_memory_ranges();

        addr = be64_to_cpu(fdm.rmr_region.destination_address) + be64_to_cpu(fdm.rmr_region.source_len);
        /* 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. */
        register_fw_dump(&fdm);
}

static int fadump_unregister_dump(struct fadump_mem_struct *fdm)
{
        int rc = 0;
        unsigned int wait_time;

        pr_debug("Un-register firmware-assisted dump\n");

        /* TODO: Add upper time limit for the delay */
        do {
                rc = rtas_call(fw_dump.ibm_configure_kernel_dump, 3, 1, NULL,
                        FADUMP_UNREGISTER, fdm,
                        sizeof(struct fadump_mem_struct));

                wait_time = rtas_busy_delay_time(rc);
                if (wait_time)
                        mdelay(wait_time);
        } while (wait_time);

        if (rc) {
                printk(KERN_ERR "Failed to un-register firmware-assisted dump."
                        " unexpected error(%d).\n", rc);
                return rc;
        }
        fw_dump.dump_registered = 0;
        return 0;
}

static int fadump_invalidate_dump(struct fadump_mem_struct *fdm)
{
        int rc = 0;
        unsigned int wait_time;

        pr_debug("Invalidating firmware-assisted dump registration\n");

        /* TODO: Add upper time limit for the delay */

        do {
                rc = rtas_call(fw_dump.ibm_configure_kernel_dump, 3, 1, NULL,
                        FADUMP_INVALIDATE, fdm,
                        sizeof(struct fadump_mem_struct));

                wait_time = rtas_busy_delay_time(rc);
                if (wait_time)
                        mdelay(wait_time);
        } while (wait_time);

        if (rc) {
                printk(KERN_ERR "Failed to invalidate firmware-assisted dump "
                        "rgistration. unexpected error(%d).\n", rc);
                return rc;
        }
        fw_dump.dump_active = 0;
        fdm_active = NULL;
        return 0;
}

void fadump_cleanup(void)
{
        /* Invalidate the registration only if dump is active. */
        if (fw_dump.dump_active) {
                init_fadump_mem_struct(&fdm,
                        be64_to_cpu(fdm_active->cpu_state_data.destination_address));
                fadump_invalidate_dump(&fdm);
        }
}

/*
 * Release the memory that was reserved in early boot to preserve the memory
 * contents. The released memory will be available for general use.
 */
static void fadump_release_memory(unsigned long begin, unsigned long end)
{
        unsigned long addr;
        unsigned long ra_start, ra_end;

        ra_start = fw_dump.reserve_dump_area_start;
        ra_end = ra_start + fw_dump.reserve_dump_area_size;

        for (addr = begin; addr < end; addr += PAGE_SIZE) {
                /*
                 * exclude the dump reserve area. Will reuse it for next
                 * fadump registration.
                 */
                if (addr <= ra_end && ((addr + PAGE_SIZE) > ra_start))
                        continue;

                free_reserved_page(pfn_to_page(addr >> PAGE_SHIFT));
        }
}

static void fadump_invalidate_release_mem(void)
{
        unsigned long reserved_area_start, reserved_area_end;
        unsigned long destination_address;

        mutex_lock(&fadump_mutex);
        if (!fw_dump.dump_active) {
                mutex_unlock(&fadump_mutex);
                return;
        }

        destination_address = be64_to_cpu(fdm_active->cpu_state_data.destination_address);
        fadump_cleanup();
        mutex_unlock(&fadump_mutex);

        /*
         * Save the current reserved memory bounds we will require them
         * later for releasing the memory for general use.
         */
        reserved_area_start = fw_dump.reserve_dump_area_start;
        reserved_area_end = reserved_area_start +
                        fw_dump.reserve_dump_area_size;
        /*
         * Setup reserve_dump_area_start and its size so that we can
         * reuse this reserved memory for Re-registration.
         */
        fw_dump.reserve_dump_area_start = destination_address;
        fw_dump.reserve_dump_area_size = get_fadump_area_size();

        fadump_release_memory(reserved_area_start, reserved_area_end);
        if (fw_dump.cpu_notes_buf) {
                fadump_cpu_notes_buf_free(
                                (unsigned long)__va(fw_dump.cpu_notes_buf),
                                fw_dump.cpu_notes_buf_size);
                fw_dump.cpu_notes_buf = 0;
                fw_dump.cpu_notes_buf_size = 0;
        }
        /* Initialize the kernel dump memory structure for FAD registration. */
        init_fadump_mem_struct(&fdm, fw_dump.reserve_dump_area_start);
}

static ssize_t fadump_release_memory_store(struct kobject *kobj,
                                        struct kobj_attribute *attr,
                                        const char *buf, size_t count)
{
        if (!fw_dump.dump_active)
                return -EPERM;

        if (buf[0] == '1') {
                /*
                 * Take away the '/proc/vmcore'. We are releasing the dump
                 * memory, hence it will not be valid anymore.
                 */
                vmcore_cleanup();
                fadump_invalidate_release_mem();

        } else
                return -EINVAL;
        return count;
}

static ssize_t fadump_enabled_show(struct kobject *kobj,
                                        struct kobj_attribute *attr,
                                        char *buf)
{
        return sprintf(buf, "%d\n", fw_dump.fadump_enabled);
}

static ssize_t fadump_register_show(struct kobject *kobj,
                                        struct kobj_attribute *attr,
                                        char *buf)
{
        return sprintf(buf, "%d\n", fw_dump.dump_registered);
}

static ssize_t fadump_register_store(struct kobject *kobj,
                                        struct kobj_attribute *attr,
                                        const char *buf, size_t count)
{
        int ret = 0;

        if (!fw_dump.fadump_enabled || fdm_active)
                return -EPERM;

        mutex_lock(&fadump_mutex);

        switch (buf[0]) {
        case '0':
                if (fw_dump.dump_registered == 0) {
                        ret = -EINVAL;
                        goto unlock_out;
                }
                /* Un-register Firmware-assisted dump */
                fadump_unregister_dump(&fdm);
                break;
        case '1':
                if (fw_dump.dump_registered == 1) {
                        ret = -EINVAL;
                        goto unlock_out;
                }
                /* Register Firmware-assisted dump */
                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)
{
        const struct fadump_mem_struct *fdm_ptr;

        if (!fw_dump.fadump_enabled)
                return 0;

        mutex_lock(&fadump_mutex);
        if (fdm_active)
                fdm_ptr = fdm_active;
        else {
                mutex_unlock(&fadump_mutex);
                fdm_ptr = &fdm;
        }

        seq_printf(m,
                        "CPU : [%#016llx-%#016llx] %#llx bytes, "
                        "Dumped: %#llx\n",
                        be64_to_cpu(fdm_ptr->cpu_state_data.destination_address),
                        be64_to_cpu(fdm_ptr->cpu_state_data.destination_address) +
                        be64_to_cpu(fdm_ptr->cpu_state_data.source_len) - 1,
                        be64_to_cpu(fdm_ptr->cpu_state_data.source_len),
                        be64_to_cpu(fdm_ptr->cpu_state_data.bytes_dumped));
        seq_printf(m,
                        "HPTE: [%#016llx-%#016llx] %#llx bytes, "
                        "Dumped: %#llx\n",
                        be64_to_cpu(fdm_ptr->hpte_region.destination_address),
                        be64_to_cpu(fdm_ptr->hpte_region.destination_address) +
                        be64_to_cpu(fdm_ptr->hpte_region.source_len) - 1,
                        be64_to_cpu(fdm_ptr->hpte_region.source_len),
                        be64_to_cpu(fdm_ptr->hpte_region.bytes_dumped));
        seq_printf(m,
                        "DUMP: [%#016llx-%#016llx] %#llx bytes, "
                        "Dumped: %#llx\n",
                        be64_to_cpu(fdm_ptr->rmr_region.destination_address),
                        be64_to_cpu(fdm_ptr->rmr_region.destination_address) +
                        be64_to_cpu(fdm_ptr->rmr_region.source_len) - 1,
                        be64_to_cpu(fdm_ptr->rmr_region.source_len),
                        be64_to_cpu(fdm_ptr->rmr_region.bytes_dumped));

        if (!fdm_active ||
                (fw_dump.reserve_dump_area_start ==
                be64_to_cpu(fdm_ptr->cpu_state_data.destination_address)))
                goto out;

        /* Dump is active. Show reserved memory region. */
        seq_printf(m,
                        "    : [%#016llx-%#016llx] %#llx bytes, "
                        "Dumped: %#llx\n",
                        (unsigned long long)fw_dump.reserve_dump_area_start,
                        be64_to_cpu(fdm_ptr->cpu_state_data.destination_address) - 1,
                        be64_to_cpu(fdm_ptr->cpu_state_data.destination_address) -
                        fw_dump.reserve_dump_area_start,
                        be64_to_cpu(fdm_ptr->cpu_state_data.destination_address) -
                        fw_dump.reserve_dump_area_start);
out:
        if (fdm_active)
                mutex_unlock(&fadump_mutex);
        return 0;
}

static struct kobj_attribute fadump_release_attr = __ATTR(fadump_release_mem,
                                                0200, NULL,
                                                fadump_release_memory_store);
static struct kobj_attribute fadump_attr = __ATTR(fadump_enabled,
                                                0444, fadump_enabled_show,
                                                NULL);
static struct kobj_attribute fadump_register_attr = __ATTR(fadump_registered,
                                                0644, fadump_register_show,
                                                fadump_register_store);

static int fadump_region_open(struct inode *inode, struct file *file)
{
        return single_open(file, fadump_region_show, inode->i_private);
}

static const struct file_operations fadump_region_fops = {
        .open    = fadump_region_open,
        .read    = seq_read,
        .llseek  = seq_lseek,
        .release = single_release,
};

static void fadump_init_files(void)
{
        struct dentry *debugfs_file;
        int rc = 0;

        rc = sysfs_create_file(kernel_kobj, &fadump_attr.attr);
        if (rc)
                printk(KERN_ERR "fadump: unable to create sysfs file"
                        " fadump_enabled (%d)\n", rc);

        rc = sysfs_create_file(kernel_kobj, &fadump_register_attr.attr);
        if (rc)
                printk(KERN_ERR "fadump: unable to create sysfs file"
                        " fadump_registered (%d)\n", rc);

        debugfs_file = debugfs_create_file("fadump_region", 0444,
                                        powerpc_debugfs_root, NULL,
                                        &fadump_region_fops);
        if (!debugfs_file)
                printk(KERN_ERR "fadump: unable to create debugfs file"
                                " fadump_region\n");

        if (fw_dump.dump_active) {
                rc = sysfs_create_file(kernel_kobj, &fadump_release_attr.attr);
                if (rc)
                        printk(KERN_ERR "fadump: unable to create sysfs file"
                                " fadump_release_mem (%d)\n", rc);
        }
        return;
}

/*
 * Prepare for firmware-assisted dump.
 */
int __init setup_fadump(void)
{
        if (!fw_dump.fadump_enabled)
                return 0;

        if (!fw_dump.fadump_supported) {
                printk(KERN_ERR "Firmware-assisted dump is not supported on"
                        " this hardware\n");
                return 0;
        }

        fadump_show_config();
        /*
         * 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 (process_fadump(fdm_active) < 0)
                        fadump_invalidate_release_mem();
        }
        /* Initialize the kernel dump memory structure for FAD registration. */
        else if (fw_dump.reserve_dump_area_size)
                init_fadump_mem_struct(&fdm, fw_dump.reserve_dump_area_start);
        fadump_init_files();

        return 1;
}
subsys_initcall(setup_fadump);