fadump.c

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/*
 * 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 <[email protected]>
 */

#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)
{
    __be32 *sections;
    int i, num_sections;
    unsigned long size;
    const int *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 0;

    fw_dump.fadump_supported = 1;
    fw_dump.ibm_configure_kernel_dump = *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 0;

    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 = 0x00000001;
    fdm->header.dump_num_sections = 3;
    fdm->header.dump_status_flag = 0;
    fdm->header.offset_first_dump_section =
        (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 = FADUMP_REQUEST_FLAG;
    fdm->cpu_state_data.source_data_type = FADUMP_CPU_STATE_DATA;
    fdm->cpu_state_data.source_address = 0;
    fdm->cpu_state_data.source_len = fw_dump.cpu_state_data_size;
    fdm->cpu_state_data.destination_address = addr;
    addr += fw_dump.cpu_state_data_size;

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

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

    return addr;
}

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 = 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 =
                fdm_active->rmr_region.destination_address +
                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->cpu_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 (reg_entry->reg_id != REG_ID("CPUEND")) {
        fadump_set_regval(regs, reg_entry->reg_id,
                    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 = fdm->cpu_state_data.destination_address;
    vaddr = __va(addr);

    reg_header = vaddr;
    if (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", reg_header->magic_number);
    pr_debug("NumCpuOffset: %x\n", reg_header->num_cpu_offset);

    vaddr += reg_header->num_cpu_offset;
    num_cpus = *((u32 *)(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 (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 = reg_entry->reg_value & FADUMP_CPU_ID_MASK;
        if (!cpumask_test_cpu(cpu, &fdh->cpu_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);

    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 ((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 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 = 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 = fdm.rmr_region.destination_address + 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,
            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;

        ClearPageReserved(pfn_to_page(addr >> PAGE_SHIFT));
        init_page_count(pfn_to_page(addr >> PAGE_SHIFT));
        free_page((unsigned long)__va(addr));
        totalram_pages++;
    }
}

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

    if (!fdm_active ||
        (fw_dump.reserve_dump_area_start ==
        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,
            fdm_ptr->cpu_state_data.destination_address - 1,
            fdm_ptr->cpu_state_data.destination_address -
            fw_dump.reserve_dump_area_start,
            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);